Natural Gas Engine: M 447 hLAG In Mercedes-Benz … Manual (Omnibus Model O 530 ... (Antilock Braking System) ... PLD Pumpe-Leitung-Düse (Pump Line Nozzle

MERCEDES-Benz Service ___________________________________________________________________

Mercedes-Benz AG • Omnibus Product Division • Status September 2003 (EvoBus-Service / AFT)

Natural Gas Engine: M 447 hLAG

In Mercedes-Benz City Bus Click bus for index

The EGM engine control unit

Foreword _____________________________________________________________________

Status September 2003 (EvoBus-Service / AFT) Page: 2 of 83

This training document is intended for the technical personnel charged with the maintenance and servicing of Mercedes-Benz omnibuses with a natural-gas power plant (M 447 hLAG). In the contents we provide information on the working and operating modes of the engine control unit (MR) EGM (electronic gas engine) of the M 447 hLAG. Details are based on the software version 14B_001 (ZCRB0A01). The specified part number serve only mark marking and distinguishing individual components. When ordering spare parts, the part numbers should always be taken from the spare parts documentation. This training document resulted as part of the temporary special measure "Support Start-Up Safeguarding for M 447 hLAG" and was supplemented with the new diagnostic functions of the software 14B_001. It is not subject to the updating service. All information correspond to the status at the time of printing. Other applicable documents (Service – EvoBus)

Title

Operating Manual (Omnibus Model O 530 – Citaro ÜSTRA)

On-Board-Diagnose (Omnibus Model O 530 – Citaro ÜSTRA)

Maintenance Sheets, Maintenance Manual (Omnibus Model O 530 – Citaro ÜSTRA)

DC Intranet (description of the natural gas Citaro and the CNG components)

September, 2003

Abbreviations _____________________________________________________________________


°DK Grad DrosselKlappe (Degrees of Throttle Valve) ABS AntiBlockierSystem – Traction Control (Antilock Braking System) AGN Automatisches Getriebe Nutzfahrzeug

(Automatic Transmission for Commercial Vehicle) ATL AbgasTurboLader (Exhaust-Gas Turbocharger) ATLR AbgasTurboLaderRegler (Exhaust-Gas Turbocharger Controller) BS Brems-Steuerung (Braking Control) CAN Controller Area Network CNG Compressed Natural Gas (primarily methane) DK DrosselKlappe (Throttle Valve) DKS DrosselKlappenSteller (Throttle Valve Actuator) DRB DRehzahlBegrenzung (Speed Limitation) EDW Elektronische DiebstahlWarnanlage (Electronic Alarm System) EGM Elektronik GasMotor (Motorregelung des Erdgasmotors)

Elektronik GasMotor (Engine Control of Natural-Gas Engine) EPW ElektroPneumatischerWandler (Electropneumatic Converter) EV EingasVentil (Gas Injector) FPS Flexibel Programmierte Steuerung (Flexibly Programmed Controller) FR FahrzeugRegelung (Vehicle Control) FSP FehlerSPeicher (Fault Memory) H-Leitung High-Leitung (CAN - High Line) HW HardWare IBIS Integriertes Bord InformationsSystem

(Integrated On-Board Information System) Kl. Klemme (Terminal) KR KlopfRegelung (Knock Control) KW KurbelWelle (Crankshaft) KWS KnickWinkelSteuerung (Knee Angle Control) KW-Sensor Drehzahlaufnehmer an der KurbelWelle (Speed Sensor on Crankshaft) L-Leitung Low-Leitung (CAN - Low Line) LLR LeerLaufRegler (Idling Controller) LMR LambdaMagerRegler (Lambda Lean Controller) LSU LambdaSondeUniversal (Universal Lambda Probe - Broadband Probe) MR MotorRegelung (Engine Control) NR NiveauRegelung (Level Control) NW NockenWelle (Camshaft) NW-Sensor Drehzahlaufnehmer an der NockenWelle OBD OnBoardDiagnose (On-Board Diagnosis) OT Oberer Totpunkt (Top Dead Centre) PLD Pumpe-Leitung-Düse

(Pump Line Nozzle - Engine Control of Diesel Engine) Prop.-Ventil (PV) ProportionalVentil (Proportional Valve) PWM PulsWeitenModulation (Pulse Width Modulation) SAS SchubAbSchaltung (Overrun Fuel Cut-Off) SG SteuerGerät (Control Unit) SW SoftWare TV TastVerhältnis (Pulse Duty Factor) WS WartungsSystem (Maintenance System) ZL Zusatz-Lenkung (Additional Steering)

Table of Contents To forward directly to relevant section, click on BOLD sections headings _____________________


1 Natural Gas Engine M 447 hLAG 8

2 Functional Description of EGM 11

2.1 Introduction 11

2.2 Torque control 13 2.2.1 Engine protection functions 14 2.2.2 Idling control 27

2.3 Engine state detection 28

2.4 Cylinder filling 28 2.4.1 Throttle valve control 29 2.4.2 Throttle valve diagnosis 30 2.4.3 Turbocharger control 31 2.4.4 Turbocharger diagnosis 34

2.5 Gas injection 35 2.5.1 Gas mass calculation during starting 35 2.5.2 Gas mass calculation in normal case 35 2.5.3 Lambda control 37 2.5.4 Lambda control diagnosis 38 2.5.5 Overrun fuel cut-off (SAS) 38 2.5.6 Switch-on conditions for gas injection 38

2.6 Ignition 40 2.6.1 Firing angle in starting mode 40 2.6.2 Firing angle determination in idling mode 40 2.6.3 Firing angle determination in partial-load and full-load mode 40

3 Electrical Description of EGM 42

3.1 System interface overview 42 3.1.1 Block diagram 42 3.1.2 Connector assignment of EGM and ignition modules 43 3.1.3 Power supply of EGM 45 3.1.4 Power supply of ignition module 46

3.2 Sensor technology 47 3.2.1 Active sensors 47 3.2.2 Special sensors 47 3.2.3 Passive sensors 48

3.3 Digital inputs 49 3.3.1 Terminal 15 49 3.3.2 Terminal 50 49 3.3.3 Service switch Start/Stop 49

3.4 Actuator technology 50 3.4.1 Gas injectors 50 3.4.2 Gas injector actuation 50 3.4.3 Proportional valve actuation 52 3.4.4 Lambda heating actuation 52 3.4.5 High-pressure cut-off valve actuation 52 3.4.6 Ignition module actuation 52

Table of Contents _____________________________________________________________________


4 Diagnosis 54

4.1 Reading measured values 54 4.1.1 Target engine torque (FR) 55 4.1.2 Maximum current engine torque 55 4.1.3 Actual engine torque 55 4.1.4 Gas injection angle (Cylinder 1) 55 4.1.5 Angle for start of gas delivery (Cylinder 1) 55 4.1.6 Current target control speed 56 4.1.7 Current final limit speed 56 4.1.8 Control-speed target value (FR) 56 4.1.9 Redundant speed (Ter. W) (FR) 56 4.1.10 Engine speed 56 4.1.11 Exhaust-gas temperature 57 4.1.12 Vehicle speed (FR) 57 4.1.13 Coolant temperature 58 4.1.14 Gas temperature 59 4.1.15 Calculation of gas pressure 60 4.1.16 Calculation of engine oil level 61 4.1.17 Oil temperature 61 4.1.18 Charge-air temperature 62 4.1.19 Boost pressure 63 4.1.20 Atmospheric air pressure 64 4.1.21 Oil pressure 65 4.1.22 Throttle-valve target position 66 4.1.23 Throttle-valve actual position 66 4.1.24 Lambda target value 66 4.1.25 Lambda actual value 66 4.1.26 Lambda-probe heating current 66 4.1.27 Lambda correction factor 67 4.1.28 Air mass 67 4.1.29 Gas mass 67 4.1.30 Firing angle (Cylinder 1) 67 4.1.31 Turbocharger pulse duty factor 67 4.1.32 Battery voltage 67

4.2 Reading binary values 68

4.3 EGM-specific Customer Service routines 71 4.3.1 Temporarily switch off LMR 71 4.3.2 Switch-off of gas injectors 72 4.3.3 Cylinder-selective ignition switch-off 72 4.3.4 Temporarily switch off engine run-on 73 4.3.5 Manual compression test 73

5 Checking EGM 74

5.1 Troubleshooting 74 5.1.1 Engine fails to start 74 5.1.2 Engine cannot be switched off 74 5.1.3 Increased engine idling speed 74 5.1.4 Reduced engine output 75 5.1.5 Rough engine running, traction interruption 75

5.2 Special tools 76

5.3 Circuit diagram of M 447 hLAG 76

5.4 Engine performance data 78

Table of Contents _____________________________________________________________________


5.5 Safety precautions when working on EGM 79

6 Appendix 80

6.1 Pulse width modulated signal 80

6.2 Overview of bus systems (EvoBus) 81

7 Index 82

List of Illustrations _____________________________________________________________________


Overall system of natural gas engine........................................................................................................ 10 Basic EGM functions ................................................................................................................................ 12 Engine protection: charge-air temperature............................................................................................... 15 Engine protection: coolant temperature................................................................................................... 16 Engine protection: turbocharger overpressure ......................................................................................... 17 Engine protection: boost-pressure substitute value formation ................................................................. 18 Engine protection: Crankshaft emergency-running mode (dual ignition)................................................... 19 Engine protection: Camshaft emergency-running mode (failure of crankshaft signal) .............................. 20 Engine protection: lambda lean-controller probe...................................................................................... 21 Engine protection: gas injection ............................................................................................................... 22 Engine protection: ignition ....................................................................................................................... 23 Engine protection: oil pressure pre-warning threshold ............................................................................. 24 Engine protection: oil-pressure warning threshold ................................................................................... 25 Idling control: target idling speed............................................................................................................. 27 Throttle valve control: TV = f(throttle valve position) ................................................................................ 29 Schematic diagram of wastegate actuation.............................................................................................. 31 Switch-on conditions for boost-pressure control...................................................................................... 32 Switch-on threshold for boost-pressure control ....................................................................................... 33 Switch-off threshold for boost-pressure control ....................................................................................... 33 Overview: gas mass calculation in normal operation................................................................................ 36 Release of gas injection and actuation of gas cut-off valve ...................................................................... 39 Function overview of firing angle calculation............................................................................................ 41 Block diagram for electrical description: .................................................................................................. 42 Actuation phases and current curve of gas injectors................................................................................ 51 Principle of ignition actuation:.................................................................................................................. 53 Determining the target engine torque ...................................................................................................... 55 Characteristic curve: Exhaust-gas temperature sensor ............................................................................ 57 Characteristic curve: Coolant temperature sensor ................................................................................... 58 Characteristic curve: Gas temperature sensor ......................................................................................... 59 Characteristic curve: Gas pressure sensor............................................................................................... 60 Characteristic curve: Oil temperature sensor........................................................................................... 61 Characteristic curve: Charge-air temperature sensor............................................................................... 62 Characteristic curve: Boost pressure sensor............................................................................................ 63 Characteristic curve: Atmospheric pressure sensor ................................................................................. 64 Characteristic curve: Oil pressure sensor................................................................................................. 65 Performance graph for O 447 hLAG, 240 kW........................................................................................... 78 Performance graph for M 447 hLAG, 185 kW .......................................................................................... 78 Drawing: pulse width modulated signal .................................................................................................... 80 Overview of bus systems (EvoBus) ........................................................................................................... 81

The M 447 hLAG Natural-Gas Engine _____________________________________________________________________


1 Natural Gas Engine M 447 hLAG

The M 447 hLAG is a further development of the M 447 hG and is used in the natural gas Citaro from Mercedes-Benz and in the CBC chassis. Technical data of engine: • 6-cylinder, inline • Natural gas operation with CNG • Lean combustion • Exhaust-gas turbocharger with wastegate control • Charge air cooling • Two output variants

240 kW @ 2,000 rpm and 1,250 Nm @ 1,500 rpm 185 kW @ 2,000 rpm and 1,050 Nm @ 1,300 rpm

• Three emission levels EURO2 EURO4 EEV (Enhanced Environmentally Friendly Vehicles)

The fuel natural gas (CNG = Compressed Natural Gas) is stored in gas pressure bottles. These are mounted crosswise on the vehicle roof. During refuelling the CNG is compressed to 200 bar. The CNG flows to the high-pressure regulator via a high-pressure line. An electrically actuated high-pressure cut-off valve is located upstream of the pressure regulator. The high-pressure cut-off valve is closed when not actuated. The high-pressure cut-off valve is actuated by the EGM. The high-pressure regulator forms the interface between the high-pressure and the low-pressure circuit. The maximum storage pressure of 200 bar is adjusted in the high-pressure regulator to an operating pressure of approx. 8 bar. As heat is absorbed from the surrounding area when the natural gas expands, the pressure regulator is heated with the engine coolant. A partial icing-up of the pressure regulator is quite normal. Complete icing-up could lead to the failure of the pressure regulator. Next the CNG relaxed to approx. 8 bar is routed through the heat exchanger. In the heat exchanger the CNG is to be conditioned to approx. 40 °C. The engine coolant also flows through the heat exchanger. The engine coolant temperature is controlled by a thermostat. The conditioned CNG flows to the injector block. The electrically actuated low-pressure cut-off valve is located at the inlet of the injector block. The low -pressure cut-off valve is closed when not actuated. The low-pressure valve is switched parallel to the high-pressure valve and is also actuated by the EGM. Twelve gas injectors (one pair per cylinder), a gas pressure and gas temperature sensor are mounted in the injector block. The gas pressure and temperature are evaluated and monitored by the EGM. The gas injectors are actuated cylinder-selectively by the EGM to meter the gas quantity fed to the engine. Finally, the exactly metered gas quantity is blown through the mixer, which is mounted before the throttle valve, into the intake duct of the engine. The combustible gas-air mixture is prepared in the mixer and the throttle valve. The natural gas engine is a spark ignition engine. The combustible gas-air mixture must be ignited by another source. The necessary ignition energy is provided by two ignition modules. Each ignition module is equipped with three ignition coils. The ignition point is controlled by the EGM and the ignition is triggered by corresponding actuation of the ignition modules.



The M 447 hLAG is a turbocharged engine. The turbocharger is a rigid-geometry turbocharger with a wastegate. The charge air pressure is controlled for the respective operating point by the EGM. For this purpose the EGM actuates the electropneumatic converter (EPW) of the wastegate. The lambda broadband probe is mounted in the exhaust section behind the turbocharger. This determines the lambda in the exhaust gas. Based on the measured lambda, the EGM can correct the gas injection accordingly if necessary so that the target lambda is complied with at all operating points (lambda control).



Overall system of natural gas engine

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Functional Description of EGM _____________________________________________________________________


2 Functional Description of EGM

2.1 Introduction

The EGM (electric gas engine) engine control unit is mounted on the engine, and is therefore part of the engine. Only one basic control unit is required for all offered output variants1 of the M 447 hLAG. The EGM is adapted to the corresponding output and engine variant with different programming. An EGM that is already programmed is considered a special engine component and may not be interchanged between different engines. An exchange of the EGM can lead to problems ranging from impairment of correct engine operation to engine and drive train damage. Exchange engines are always delivered complete with the engine wiring harness and the related EGM engine control unit. To be able to distinguish between different control units, each unit is provided with a sticker. The data record number (1) with which the EGM is programmed is indicated at the top of the sticker. This data record number should always be specified when purchasing a replacement. The EGM engine control unit is an electronic spark-ignition engine control unit for engines of the 447 and 900 series. The EGM's design is based on the PLD diesel engine control unit and is virtually identical to the PLD on the outside. Open and closed-loop control functions which can be used both for diesel and spark-ignition engines have been adopted from the PLD in the EGM. Examples include: • Engine control with torque interface • Camshaft/crankshaft signal detection • CAN and ISO-K interfaces • Oil level sensing • PIN assignment of vehicle connector • Service engine switch Start/Stop • Starter control The functions specific to spark-ignition engines have been newly developed. The main open and closed-loop control functions are: • Air mass control by electronic throttle valve and boost-pressure control • Dwell and firing-angle control • Sequential gas injection with variable start of gas injection • Lambda control with broadband probe for lambda = 1 and lean operation • Engine protection functions • Diagnostic functions

1 The output variants with 185 kW (rigid vehicle) and 240 kW (articulated vehicle) are currently available



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Basic EGM functions



2.2 Torque control

Like the PLD, the EGM is a torque-based engine control unit. The EGM receives the torque specification from the FR via a CAN bus. The torque specification refers to the engine output shaft and corresponds to the torque requested by the driver (interpretation of the accelerator pedal position by the FR). With functioning CAN communication, the EGM actuates the corresponding actuators so that the requested torque (torque specification) is present at the engine output. Expressed in simplified terms, this consists of the following steps: 1) Control of cylinder filling

In accordance with the specification target engine torque (FR) and the current engine speed, the EGM determines the DK target position and the target charge air pressure from corresponding maps and actuates these accordingly.

2) Determination of air mass In the next step the air mass present in the cylinders is calculated based on the measured boost pressure (determination of cylinder filling).

3) Calculation of gas mass to be injected With the knowledge of the air mass and taking the target lambda and the lambda correction value into account, the gas mass to be injected is calculated in the next step.

4) Conducting gas injection The gas injection angle is calculated from the gas mass while taking the operating conditions into account. The cylinder-selective gas injection begins with the gas-injection starting angle and ranges over the gas injection angle.

5) Mixture ignition The firing angle is determined as a function of the air mass and the current engine speed. The cylinder-selective ignition is realised by corresponding actuation of the ignition modules.

6) Checking actual lambda (lambda control) The lambda probe mounted in the exhaust section behind the turbocharger determines the actual lambda in the exhaust gas. The lambda controller of the EGM compares the target and the actual lambda and determines the lambda correction factor from the result. This is taken into account when determining the gas mass.

The combination of air mass (cylinder filling), gas injection mass (gas injection) and firing angle (ignition) results in the target engine torque (FR) at the engine output shaft requested by the driver. The engine torque output by the engine is calculated from a map and transferred as the absolute actual engine torque.



2.2.1 Engine protection functions

Several functions for protecting the engine under unfavourable engine operating conditions (high coolant temperature, high charge-air temperature etc.) and in case of errors in the sensor technology, actuators or mechanical systems are implemented in the EGM engine control unit. These can result in the possible torque at full load being limited by the engine protection functions. In order not to endanger the engine's availability, the engine protection functions – with the exception of the engine protection function: Dual ignition – not active during starting. The following engine protection functions can be active in the MR EGM: 1) Engine protection: charge-air temperature

In the case of an impermissibly high charge-air temperature, the permissible engine torque is reduced as a function of the charge-air temperature.

2) Engine protection: coolant temperature In the case of an impermissibly high coolant temperature, the permissible engine torque is reduced as a function of the coolant temperature.

3) Engine protection: turbocharger overpressure In the case of an impermissibly high boost pressure, the permissible engine torque is reduced as a function of the boost pressure.

4) Engine protection: boost-pressure substitute value formation If the boost-pressure sensor fails, the engine continues to be operated in the emergency running mode. The basis for the emergency running mode is an estimated boost pressure. The available engine torque is limited as a function of the engine speed.

5) Engine protection: camshaft emergency-running mode If the camshaft signal fails, the engine is operated in the crankshaft emergency running mode with dual ignition (only if camshaft signal has already failed prior to engine starting). In case of operation with dual ignition, the available engine torque is limited as a function of the engine speed.

6) Engine protection: camshaft emergency-running mode If the crankshaft signal fails, the engine is operated in the camshaft emergency running mode. The available engine torque is limited as a function of the engine speed.

7) Engine protection: lambda lean-controller probe If the lambda sensor fails, the available engine torque is reduced as a function of the engine speed.

8) Engine protection: gas injection In case of faults in the gas injection actuators (gas injection valves and supply lines), the corresponding emergency running measures are initiated and the maximum possible engine torque is limited as a function of the engine speed.

9) Engine protection: ignition In case of errors in the actuation of the ignition modules (primary-side), the engine switches over to an increased idling speed and the available engine torque is greatly limited.

10) Engine protection: oil pressure For engine protection at a low oil pressure, a two-stage warning concept (similar to that used with the PLD) has been realised. It is ONLY a warning concept – engine operation remains unchanged (no affect on engine operation).

11) Engine protection: overspeed To protect the engine against overspeed, first the throttle valve is closed , and if the engine speed continues to increase, gas injection is cancelled.

12) Engine protection: exhaust-gas temperature



To protect the catalyst at excessively high exhaust-gas temperatures, the available engine torque is limited as a function of the engine speed and exhaust-gas temperature according to the catalyst and engine speed.

2.2.1.1 Engine protection: charge-air temperature

The engine protection function charge-air temperature is intended to reduce the maximum permissible engine torque at excessively high charge-air temperatures. The value for the reduction of the available engine torque is calculated with the engine running from a characteristic curve as a function of the charge-air temperature and multiplied by the target engine torque. Engine protection: charge-air temperature

Charge-air temperature Characteristic curve

Torque limitation at charge-air temperature

Charge air Limitation factor

Title: Service EGM: Motorschutz File: kd_mts_LLT.vsd Date of last change: 2001-09-12

MOB - Torque Limitation at Charge-Air Temperature Factor [-] = f(Charge-air temp.[°C])

Fact

or

Charge-Air Temperature



2.2.1.2 Engine protection: coolant temperature

The engine protection function coolant temperature is used to protect the engine against operation at impermissibly high coolant temperatures. This function consists of two parts which are processed independently of the engine state. • Coolant temperature monitoring

If the coolant temperature is higher than 98 °C, then a coolant temperature pre-warning is requested. To attenuate the pre-warning, it is not cancelled until the coolant temperature is at least 1 °C less than the pre-warning threshold. If the coolant temperature is higher than 105 °C, then the warning buzzer is activated. Here as well, a hysteresis of 1 °C is implemented before the warning buzzer request due to an excessively high coolant temperature is cancelled again when the temperature drops. When the warning buzzer is requested, the fault 2122 "Coolant temp. too high" is stored in the fault memory. The coolant temperature is monitored every 40 ms regardless of the engine state.

• Torque reduction From a characteristic curve as a function of the coolant temperature, a limiting factor for torque reduction is calculated ("boiling protection"), the target engine torque (FR) is multiplied by this limiting factor and the engine torque is reduced accordingly.

Engine protection: coolant temperature

Coolant temperature Coolant temperature Limitation factor

Characteristic curve

Coolant-temperature limitation characteristic curve

Title: Service EGM: Motorschutz File: kd_mts_tmot.vsd Date of last change 2001-09-12

MOB - Torque limitation at coolant temperature Limitation factor [-] = f(Coolant temperature [°C] )

Lim

itatio

n fa

ctor

Engine temperature



2.2.1.3 Engine protection: turbocharger overpressure

The engine protection function turbocharger overpressure is used to protect the engine during operation against impermissibly high boost pressures ("turbocharger overpressure"), e.g. in case of a defective "wastegate". • Turbocharger overpressure detection

If the actual boost pressure is above the permissible value of 2.35 bar for longer than 15 seconds, then the event "Boost pressure too high" is detected and the fault code 1820 is entered. This limit pressure check takes place cyclically every 40 ms. An active overpressure fault is first reset in the engine state "Engine stopped" with the engine stopped. If the boost-pressure only briefly exceeds the currently permissible value, the fault debouncing begins again from the start the next time the limit is exceeded.

• Torque limitation The full-load torque is limited by a factor dependent on the boost pressure to protect the turbocharger and the engine.

Engine protection: turbocharger overpressure

Boost pressure

Torque limitation with turbocharger overpressure

Engine protection: overpressure limitation File: kd_mts_p2.vsd Date: 29.09.2000

Boost pressure Limitation torque


MOB - Torque limitation with charge-air overpressure Max. target torque [Nm] = f(Boost pressure [bar])

Torq

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Boost pressure



2.2.1.4 Engine protection: boost-pressure substitute value formation

The boost-pressure signal is the most important information of the EGM and the condition for realising correct operation of the natural gas engine. From the boost-pressure signal the EGM determines the air mass present in the combustion chambers. Based on this information, the gas mass to be injected is calculated taking the target lambda into account. If the boost-pressure sensor fails, the EGM must estimate the air mass in the combustion chambers to continue engine operation. This is only possible in the engine "intake mode", and therefore the wastegate of the exhaust-gas turbocharger is opened when the boost-pressure sensor fails to largely prevent turbocharging. The engine protection function: "Boost-pressure substitute value formation" is run when: a) the engine control detects a broken wire of the boost-pressure sensor (fault code: 1415) or b) the engine control detects a short-circuit to earth of the boost-pressure sensor (fault code 1416) In the case of a fault, the available engine torque is limited as a function of the engine speed. Engine protection: boost-pressure substitute value formation

MOB - Torque limitation with boost-pressure substitute value formation Factor [-] = f(Speed [rpm])

Lim

itatio

n fa

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Speed



2.2.1.5 Engine protection: camshaft emergency-running mode

To detect and evaluate the current crank angle and the engine speed, the M 447 hLAG is equipped with two inductive speed sensors – one crankshaft sensor and one camshaft sensor. Both speed sensors are evaluated and monitored by the engine control. As the resolution of the crankshaft sensor is higher than that of the camshaft sensor (more tooth faces on the crankshaft gear), the crankshaft signal is normally used for determining the crank angle. The camshaft signal is required for system synchronisation and when the crankshaft signal fails. If the camshaft signal fails before "system synchronisation" , the engine control switches into the crankshaft emergency-running mode. In the crankshaft emergency-running mode the so-called dual ignition (two cylinders are ignited simultaneously) takes place and the torque reduction is carried out as a function of the engine speed. If the camshaft sensor fails after "system synchronisation" is carried out, engine operation is maintained without restriction. Note: To accelerate the engine run-up during starting, starting is carried out with dual ignition (cylinder-selective gas injection and firing of two cylinders). Engine protection: Crankshaft emergency-running mode (dual ignition)

Engine speed Characteristic curve

Dual ignition Limitation torque

Torque limitation with dual ignition

Title: Engine protection File: kd_mts_doppelzündung.vsd Date of last change: 2001-09-12

MOB - Torque limitation with dual ignition / Crankshaft emergency-running mode Torque [Nm] = f(Speed [rpm])

To

rque

Speed



2.2.1.6 Engine protection: camshaft emergency-running mode

To detect and evaluate the current crank angle and the engine speed, the M 447 hLAG is equipped with two inductive speed sensors – one crankshaft sensor and one camshaft sensor. Both speed sensors are evaluated and monitored by the engine control. As the resolution of the crankshaft sensor is higher than that of the camshaft sensor (more tooth faces on the crankshaft gear), this sensor is normally used for determining the crank angle. The camshaft signal is required for system synchronisation and when the crankshaft signal fails. If the crankshaft signal fails (camshaft emergency-running mode), the crank angle is determined based on the camshaft signal. Virtually unrestricted engine operation can be maintained. As the crank angle determination is carried out less accurately with the camshaft sensor than with the crankshaft sensor, the available engine torque in the camshaft emergency-running mode is limited as a function of the engine speed. Engine protection: Camshaft emergency-running mode (failure of crankshaft signal)

Engine speed Characteristic curve

Torque limitation Camshaft e.-running mode

Camshaft e.-running mode Limitation factor

Title: Service EGM: Engine protection File: kd_mts_NW_Notlauf.vsd Date of last change: 2001-09-12

MOB - Torque limitation with camshaft e.-running mode Factor [-] = f(Speed [rpm])

To

rque

Speed



2.2.1.7 Engine protection: lambda lean-controller probe

The engine protection function lambda lean-controller probe is intended to reduce the maximum permissible engine torque if the lambda correction factor differs too greatly and/or in the case of an implausible probe heating current. The engine protection function: "Lambda lean-controller probe" is run when: c) the engine control has detected an extremely great deviation of the lambda correction factor with the

corresponding fault memory entry 0775: "Control deviation too great" or d) the engine control has detected an implausible probe heating current with the corresponding fault

memory entry 8417: "Measuring range implausible" . The value for the reduction of the limit torque is calculated from a characteristic curve as a function of the engine speed. The engine protection function lambda lean-controller probe is run in the 40 ms time slice. Engine protection: lambda lean-controller probe

Engine speed LMR time-outLimitation torque


Torque limitation LMRmanip. variable deviation

Title: Service EGM: Engine protectionFile:Date of last change: 16.09.2003

MOB - Torque limitation with LMR manip. variable deviation Max. torque [Nm] = f(Speed [rpm])

To

rque

Speed



2.2.1.8 Engine protection: gas injection

From the software version 13A, the EGM engine control unit is capable of detecting fault states on the gas injectors and their wiring. In the case of a fault, corresponding fault codes are stored in the fault memory and emergency running measures are initiated. As full engine output is not possible in the case of a failure of individual gas injectors, this is intentionally limited in dependence on the number of failed gas injectors and the engine speed. The EGM engine control unit is capable of compensating the failure of up to three "gas injector pairs"; if an additional injector pair fails, the engine is switched off. Engine protection: gas injection

Fault on Gas Injector Measures Break in wiring

Interturn fault

- Torque reduction: 20 % per failed "injector pair" - The actuation of the corresponding "injector pair" is deactivated - Ignition remains completely switched on (all cylinders) - Lambda control remains switched on

Fault on Bank Supply Measures

Break in wiring

Short circuit to ground

- Torque reduction: 20 % per failed "injector pair" - The actuation of the corresponding "injector pairs" is deactivated - Ignition remains completely switched on (all cylinders) - Lambda control remains switched on

T itle: Diagnosis of gas injeciton (Cyl. 1-6), Ub short-circuit, short-circuit to earth, break in wiring F ile: kd_hwd_eingasung_übersicht.vsd Date of last change: 2001-08-22

G as injector actuation of engine control

+ -Battery

+ - Battery

Ub short-circuit

Short-circuit to earth

Bank supply L. probe switch 1 L. probe switch 3

L. probe switch 2

+ -Battery

+ - Battery


Ub short-circuit B

reak

in w

iring

Bre

ak in

wiri

ng

bank-selective detection valve-selective detection

Inte

rtur

n fa

ult

- no detection- Control unit destruction no detection

no detection



2.2.1.9 Engine protection: ignition

From the software version 13A, the EGM engine control unit is capable of detecting breaks in wiring on the primary side and interturn faults on the actuation cables of the ignition modules. In the case of a fault, the corresponding fault codes are stored in the fault memory and corresponding emergency running measures are initiated. The EGM engine control unit is capable of compensating the failure of up to three cylinders; if an additional cylinder fails, the engine is switched off. Engine protection: ignition

Title: Diagnosis of gas injeciton (Cyl. 1-6), Ub short-circuit, short-circuit to earth, break in wiringFile: kd_hwd_zuendung_Fehlerdarstellung.vsd Date of last change: 2001-08-22

Actuation of engine control

4 3 Ignition module

5

Kl. GND

+ -Battery


Bre

ak in

w

iring

+ -Battery

Ub short-circuit

As in the case of defective actuation of the ignition modules, a failure of the ignition on the corresponding cylinder should be assumed, the engine availability is greatly reduced if a fault occurs. If a fault occurs: - the torque specification of the driver is ignored (limited to zero), - an increased engine idling speed of approx. 900 rpm is set and - the lambda control is switched off. Note: • Faults in the secondary side of the ignition system can NOT currently be directly detected by the

EGM engine control unit!! • An indirect detection is possible from software version 14A with the exhaust-gas temperature sensor

following the catalyst. The conditions is that the catalyst has reached the operating temperature.



2.2.1.10 Engine protection: oil pressure

With the engine protection function oil pressure it is currently possible to display a two-stage warning concept. The engine protection function is calculated every 10 ms in the engine-on mode with insufficient oil pressure, and in the other states ("Engine stopped", Start") the function is reset. • Blocking time after Start operation

As the oil pressure may at first be built up with a delay following engine starting, the oil pressure engine protection function can be blocked for a period of 10 seconds after start operation (transition from engine state "Start" to "Normal operation"). The function remains reset, i.e. no oil pressure warnings are output.

• Oil pressure warnings

Depending on the speed, two characteristic curves are available with which the respective minimum permissible oil pressure can be described. If the oil pressure drops below the threshold value from the pre-warning characteristic curve, the oil pressure pre-warning is transmitted. If the oil pressure drops below the threshold value from the warning characteristic curve, the oil pressure pre-warning is cancelled and the oil-pressure warning is transmitted via the CAN.

Engine protection: oil pressure pre-warning threshold

MTS - Oil-pressure pre-warning threshold Oil pressure threshold [bar] = f(Speed [rpm])

P

oil

MIN

Speed



Engine protection: oil-pressure warning threshold

MTS - Oil-pressure warning threshold Oil pressure threshold [bar] = f(Speed [rpm])

P

oil

MIN

Speed

2.2.1.11 Engine protection: overspeed

To protect the engine against operation at an impermissibly high speed ("overspeed"), an overspeed protection function is implemented in the control unit. This is calculated at intervals of 10 ms regardless of the engine state. If the engine speed exceeds the threshold of 2,360 rpm for soft speed limitation (DRB soft), then the overspeed protection function activates the soft speed limitation in the first step. In the process the throttle valve is moved into the position 2° DK. If the engine speed exceeds the threshold of 2,400 rpm for hard speed limitation (DRB hard), then the overspeed protection function also switches off the gas injection in the second step until the condition for hard speed limitation is no longer met.

2.2.1.12 Engine protection: exhaust-gas temperature

To protect the catalyst and adjacent components from excessively high temperatures ("Cat fire"), the exhaust-gas temperature after the catalyst is monitored. Due to malfunctions in the ignition of gas injection, the catalyst may be flooded with unburned gas. If the catalyst is already at operating temperature, extremely high temperatures result in the catalyst due to the increased transfer of gas and residual air. If the exhaust-gas temperature exceeds 650 °C, a warning is set and the available engine torque is greatly reduced. From 700 °C the red warning lamp and the warning buzzer are actuated and the vehicle should be stopped as quickly as possible and the engine switched off.



Engine protection: exhaust-gas temperature

Exhaust-gas temperature Limitation torque

Torque limitationExhaust-gas temperature

MapExhaust-gas temperature

Engine speed

MOB - Torque limiation with exhaust-gas temperature Max. torque [Nm] = f(E. gas temp.[°C], Speed [rpm])

Exhaust-gas temperature [°C]

Max. torque [Nm]

Speed [rpm]



2.2.2 Idling control

Engine idling is controlled by the EGM. Customer Service cannot influence the idling controller – no adjustment work is required or possible. The target idling speed is dependent on the coolant temperature. Idling control: target idling speed

The idling controller operates independently of the engine state – the LLR can operate both in the engine state "Idling" and in the partial and full-load operating modes. Minor speed dips during load connection (e.g. when starting off at traffic lights, switching on the air conditioner etc.) and slow adjustment of the target idling speed compared to the diesel engine are typical for the M 447 hLAG and normal. Poor, rough idling frequently indicates problems in the ignition system. An increased idling speed frequently indicates the entrance of unmetered air, which the engine draws past the throttle valve.

LLR - Target idling speed Speed [rpm] = f(Engine temperature [°C] )

Targ

et id

ling

spee

d

Engine temperature



2.3 Engine state detection

The engine state detection is a central part of the EGM torque control. The engine state detection is used to determine the current engine state2. This is checked every 10 ms. Based on the determined engine state, the related functions for calculating the target torque, and with it all other variables, are then worked through. In the current engine state, invalid functions are reset or remain in a defined state. The engine state is understood as the strategy for engine filling, gas injection and ignition. If the engine state changes, initialisations are carried out in some cases. The following engine states are differentiated: Engine stopped no gas injection, no ignition,

gas cut-off valve closed Engine starting time-controlled cylinder filling and gas injection

Normal operation Idling3, partial load4 or full load5 torque-based operation

The individual state is determined here with the engine speed. • Engine state "Engine stopped"

The EGM detects this state when the engine speed is less than 51 rpm. • Engine state "Engine starting"

The engine state changes from the "Engine stopped" state to the "Engine starting" state as soon as the engine speed is greater than or equal to 51 rpm. The engine state changes from the "Normal operation" state to the "Engine starting" state as soon as the engine speed is less than 71 rpm (starter DOES NOT engage). The engine state "Engine starting" is an operating mode controlled according to a fixed sequence. The torque request has no effect. Due to the selected speed values for the engine state change, the engine is also in the starting mode in the normal-operation engine state, as the starter speed considerably exceeds the limit for the state change.

• Engine state "Normal operation"

In the remaining speed range the normal-operation engine state is detected. In this state the states idling, partial-load and full-load operation are also differentiated in dependence on the target engine torque (FR) 6. If the target engine torque (FR) is less than 150 Nm, then idling is detected. If the target engine torque is greater than or equal to 150 Nm, then partial load is detected (the full-load state does not exist).

2.4 Cylinder filling

To control the filling of the combustion chambers with fresh gas, the throttle valve and the boost pressure must be controlled and regulated in accordance with the target torque specification, the engine speed and the engine state.

2 Variable in Star diagnosis or on-board diagnosis (binary value 1, bit 0 and 1) 3 Größe in Star-Diagnosis bzw. On-Board-Diagnose (Binärwert 1, Bit 2 und 3) 4 Größe in Star-Diagnosis bzw. On-Board-Diagnose (Binärwert 1, Bit 4 und 5) 5 Größe in Star-Diagnosis bzw. On-Board-Diagnose (Binärwert 6, Bit 0 und 7) 6 Variable in Star diagnosis or on-board diagnosis (measured value 1)



2.4.1 Throttle valve control

The throttle valve of the M 447 hLAG is positioned by an electric throttle valve actuator (DKS from Woodward). The throttle valve actuator has its own integrated power and control electronics. The throttle valve, electrical throttle valve actuator and the electronics form a unit. The throttle valve actuator is supplied with power from the vehicle (not by the EGM). The actuator receives a target specification from the EGM - the throttle-valve target position7. The electronics integrated in the throttle valve carries out the position control of the throttle valve and returns a position feedback to the EGM - the throttle-valve actual position8. This means the position control of the throttle valve is not carried out by the EGM, but instead by the throttle valve actuator itself. The target specification of the EGM is a PWM signal. The throttle valve actuator interprets the pulse duty factor as the specification for the throttle-valve target position. Throttle valve control: TV = f(throttle valve position)

7 Variable in Star diagnosis or on-board diagnosis (measured value 22) 8 Variable in Star diagnosis or on-board diagnosis (measured value 23)

DK - Pulse duty factor Woodward - throttle valve TV [%] = f(target value)

TV

Target value



2.4.2 Throttle valve diagnosis

The position feedback sent by the throttle valve actuator to the EGM is an analogue signal in the range from approx. 0.3 V to 4.7 V. Due to the low accuracy of the EGM, the analogue signal "throttle-valve actual position" is only used for diagnostic purposes. Three monitoring functions are realised in the EGM. • Throttle-valve reference movement

After each ignition switch-on (Ter. 15), the so-called throttle-valve reference movement is carried out. In the process, the throttle valve must first move in the closed direction, then in the open direction and reach the pre-programmed end positions within a certain time window when doing so. If the reference movement fails, the event "Throttle valve actuator – general positioning error" is detected and the fault code 8378 is entered. If this fault occurs, the gas injection is blocked and it is NOT possible to start the engine!!

• Exceeding of minimum/maximum thresholds

If the voltage of the throttle-valve position sensor is above 4.7 V or below 0.3 V for a period of 2 seconds, then the event "Measuring range exceeded or dropped below" is detected and the fault codes 8116 or 8115 is entered. These fault memory entries only serve as information and do not result in any measures by the EGM.

• Manipulated variable deviation Very large manipulated variable deviations that may be critical to safety are detected by the EGM, displayed and corresponding protective measures are initiated. If the manipulated variable deviation is more than 30 °DK or more than -20 °DK for the duration of at least one second, then the event "Throttle-valve actuator manipulated variable deviation" is detected and the fault code 8374 is entered. Then the threshold for hard speed limitation (DRB hard) is reduced from 2,400 rpm to 1,200 rpm ( see Engine protection: overspeed)



2.4.3 Turbocharger control

The M 447 hLAG is equipped with a water-cooled rigid-geometry turbocharger. Output control is realised with a wastegate. The wastegate is actuated by a pneumatic actuator. If the pneumatic actuator is not charged with pressure, then the wastegate is closed. Schematic diagram of wastegate actuation

The operating pressure of the pneumatic actuator is controlled by an electropneumatic converter (EPW). The EGM carries out a boost-pressure control and actuates the EPW with a PWM of 120 Hz and a variable pulse duty factor. The boost-pressure control is calculated in a 20 ms time grid. The EPW for actuating the boost pressure is not actuated in the engine states "Engine stopped" and "Starting". In the "Normal operation" engine state the target boost pressure is a function of the requested vehicle torque and the engine speed.



Switch-on conditions for boost-pressure control

Speed threshold for ATL ON is 400 rpm Speed threshold for ATL OFF is 300 rpm

Engine speed

ATL controller ON

Speed threshold ATL on

Target boost pressure >


>

Engine speed

Speed threshold ATL off

Target boost pressure

Caracteristic curve

<

<

≥ 1

B.-press. threshold ATL onn

B.-press. threshold ATL off

Fault memory entry 1415

S Q

R

Prop. valve 1 alternative function activated

Supply Bank 1 off Title: ATL- Einschaltbedingungen File: kd_atl_esb.vsd Datum der letzten Änderung: 2001-09-13

&

Switch-on conditions

Fault memory entry 1416

Switch-off conditions



Switch-on threshold for boost-pressure control

Switch-off threshold for boost-pressure control

DK - Boost-pressure threshold ATL on Target b.-press. [bar] = f(speed [rpm] )

Targ

et b

oost

pre

ssur

e

Speed

DK - Boost-pressure threshold ATL off Target b.-press. [bar] = f(speed [rpm] )

Targ

et b

oost

pre

ssur

e

Speed



2.4.4 Turbocharger diagnosis

By comparing the target boost pressure and the actually measured boost pressure, the EGM can deduce that there are malfunctions in the turbocharger circuit. Two monitoring functions are realised in the EGM. • Overpressure detection


• Overpressure detection


• Plausibility of turbocharger circuit

From the speed of 1,400 rpm and a torque request greater than 1,000 Nm, the boost pressure must lie within a defined range [350 mbar < (p_LLuf – p_atmosphere) < 1,500 mbar] above the atmospheric pressure, i.e. the turbocharger must have built up a defined gauge pressure. If no limit function (e.g. engine protection, end limitation) is effective, checking is carried out for a maximum and a minimum permissible overpressure. If under the above operating conditions the boost pressure fails to reach the expected minimum pressure following a debounce time of 5 seconds, or if the boost pressure exceeds the maximum permissible overpressure, a boost circuit fault (fault code 1818) is entered in the fault memory. In the first case a fault can, for example, occur in the air guidance system (e.g. air hose defective), and in the second case, for example, a fault can occur on the turbocharger (wastegate).

The turbocharger circuit check is carried out every 40 ms. The test is only carried out when both the boost-pressure and the atmospheric-pressure sensor are electrically okay and supply plausible values.



2.5 Gas injection

The fuel (here CNG) is injected by cylinder-selective actuation of the gas injectors following successful crankshaft/camshaft synchronisation. The injectors are actuated in two phases. In the first phase, the so-called push phase, the injectors are heavily charged with current to open them quickly and completely. The push phase follows the hold phase in which the injectors are charged with less current to protect them from overheating. The quantity of the injected fuel is proportional to the entire actuation time, the injection time and/or the injection angle. The injection time is calculated from the gas mass to be injected. The gas mass is determined time-controlled in the starting mode and remains unaffected by the lambda control, while the determination of the gas mass outside the starting mode is mainly based on the air mass and the other correction functions such as warm-up correction etc.

2.5.1 Gas mass calculation during starting

The starting gas mass results from the basic injection mass, which is corrected during starting in accordance with the existing basic conditions. The environmental influences starting temperature and ambient pressure can each be taken into account accordingly in the forma of a characteristic curve. The engine speed and ignition number can also be taken into account with a characteristic curve.

2.5.2 Gas mass calculation in normal case

The calculation of the gas mass to be injected outside of starting is mainly based on the air mass fed to the engine, the stoichiometric mass ratio of air and the natural gas used and the lambda target value. In addition, the gas mass based on the variables previously named is charged as needed with warm-up and dynamic enrichment. • Mass ratio

The mass ratio corresponds to the quotients of air mass and gas mass for stoichiometric operation (lambda = 1). The mass ratio can be subject to large fluctuations depending on the natural gas used. From software version 14A these fluctuations are taken into account via the formation of a mean value of the lambda correction factor when calculating the gas mass.

• Basic adjustment In the basic adjustment maps the lambda target value is defined as a function of the air mass and the engine speed dependent on the operating point. The basic adjustment factor is used to calculate the gas mass as the target value specification.

• Warm-up correction The warm-up correction enables special enrichment to be carried out for the warm-up mode. This permits improved engine operation and provides for higher exhaust-gas temperatures to shorten the warm-up phase. The intensity of the warm-up correction is dependent on the coolant temperature. The warm-up correction is completed when the coolant temperature has reached approx. 35 °C.

• Lambda control The target value for the lambda control is the basic adjustment factor. The gas mass is corrected with the lambda correction factor in dependence on the lambda target-actual difference.

• Dynamic gas enrichment An additional gas mass enrichment is required in dynamic engine operating states. Several functions are realised in the EGM for this purpose.

• Gas quality detection From software version 14A a gas quality detection function is realised to adapt the lambda target value and the firing angle to the special requirements of high gas. A change in the gas quality can be detected by means of a mean value formation of the lambda correction factor.



Overview: gas mass calculation in normal operation

Basic adjustment

Mass ratio

Warm-up correction

:

Gas mass

:

Air mass g/stroke

Gas mass (uncorrected) [g/stroke]

Gas injection/gas mass determination in normal case File: kd_gas_m_best.vsd Datum: 08.10.2000

Air mass

Basic factor

Warm-up -

factor

Limitation

Basic adjustment if fault in lambda control

Fault in lambda control

Dynamic correction functions

Basic adjustment MAX limitation (lambda)

Basic adjustment MIN limitation (lambda)

Lambda control

Lambda- correction factor [%]

Lambda mean value formation

1



2.5.3 Lambda control

The M 447 hLAG is a lean engine with lambda control. The lambda controller integrated in the EGM is responsible for compliance with the pre-programmed target lambda in all engine operating points. During idling the target lambda is equivalent to approx. 1.2, however is changed by the EGM in dependence on the control deviation by up to ± 0.2 as needed. The target lambda in partial-load operation is dependent on the engine speed and the air mass. The target lambda lies in the range of approx. 1.1 to 1.6. Target lambda in partial-load operation

To measure the real actual lambda, a lambda probe (broadband probe) is integrated in the exhaust system between the turbocharger and the catalyst. Input variables of the lambda controller are the target lambda and the actual lambda. The lambda controller supplies the lambda correction factor. This is integrated in the calculation of the gas mass. As a result, the lambda controller can ensure compliance with the target lambda by correcting the injected gas mass. A positive lambda correction factor means that – always starting from the target lambda dependent on the operating point – the combustion is too lean so that the engine control must inject gas as a reaction. Conversely, a negative lambda correction factor means that the combustion is too rich, i.e. too much gas is injected.

GAP - Basic adjustment (LOW-gas) Factor injection (LOW-gas) [.] = f(Speed[rpm], filled air mass [g/stroke]

Speed Air mass



2.5.4 Lambda control diagnosis

When the entire natural-gas engine system is operating properly, the lambda correction factor should be approx. ± 5 % in stationary operating points. A clear deviation from these values can have serious consequences for the engine and catalyst, and therefore this value is monitored by the EGM. If the value of the lambda correction factor is above 0.20 or below -0.25 for more than 20 seconds, then the result "Lambda controller: control deviation too great" is detected and the fault code 0775 is set. As a reaction to this fault, the Engine protection: lambda lean-controller probe becomes active and the engine is only operated further controlled (lambda control OFF). A substitute value of 1.2 is selected for the target lambda.

2.5.5 Overrun fuel cut-off (SAS)

The overrun fuel cut-off (SAS) of the M 447 hLAG is realised in the EGM. The overrun fuel cut-off is a function of the target engine torque (FR), engine speed and vehicle speed. The overrun fuel cut-off process is divided into the sub-processes SAS_soft (soft overrun fuel cut-off) and SAS_hard (hard overrun fuel cut-off). While the overrun fuel cut-off is active, the throttle valve is moved into a throttle valve position dependent on the engine speed and gas injection is prevented.

2.5.6 Switch-on conditions for gas injection

So that the previously calculated gas injection mass may also actually be injected by the control unit, several conditions must be met beforehand. In addition, the gas cut-off valve must be actuated to release gas for gas injection (open gas cut-off valve).



Release of gas injection and actuation of gas cut-off valve

Zero

qua

ntity

(req

uest

via

CAN

) En

gine

sta

te: e

ngin

e st

oppe

d

Ter.

15

OFF

Faul

t cod

e 83

78: T

hrot

tle v

alve

act

uato

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ener

al a

ctua

ting

faul

t

Engi

ne s

tate

: eng

ine

stop

ped

Spee

d lim

itatio

n: h

ard

spee

d lim

itatio

n

Ove

rrun

fuel

cut

-off

STO

P bu

tton

Zero

qua

ntity

(req

uest

via

CAN

) ≥

1

Gas

cut

-off

val

ve

OFF

ON

Gas

inje

ctio

n O

FF

ON

Title

: Se

rvic

e EG

M: G

as r

elea

se

File

: kd

_cng

_gas

_fre

i.vsd

D

atum

der

letz

ten

Ände

rung

: 08.

08.2

003

Con

diti

ons

for

rele

ase

of g

as c

ut-o

ff v

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≥ 1

Faul

t cod

e 83

78: T

hrot

tle v

alve

act

uato

r - g

ener

al a

ctua

ting

faul

t

Faul

t cod

e 49

09: G

as in

ject

or b

ank

2 - b

reak

in w

iring

Fa

ult c

ode

4908

: Gas

inje

ctor

ban

k 2

- sho

rt-c

ircui

t to

eart

h

Con

diti

ons

for

rele

ase

of g

as m

ass

calc

ulat

ion

Mot

or s

top

switc

h ac

tuat

ed



2.6 Ignition

The ignition is carried out as cylinder-selective ignition. The ignition is triggered as soon as the system is synchronised. The procedure for calculating the ignition angle differs considerably from the engine state. There is a special calculating specification for determining the firing angle in the engine state: Starting, a different one in the idling mode and another in the partial and full-load operating modes.

2.6.1 Firing angle in starting mode

In the starting mode the firing angle is interpolated from a characteristic curve as a function of the engine speed and also provided with an offset dependent on the coolant temperature.

2.6.2 Firing angle determination in idling mode

In the idling mode the firing angle is mainly determined by the engine speed. Depending on the engine speed, one firing angle is interpolated for the warm engine state and one for the cold engine state. The individual firing angle (for the warm and cold state) are weighted with a factor dependent on the coolant temperature and added together. In addition, the idling speed is affected by the firing angle.

2.6.3 Firing angle determination in partial-load and full-load mode

In partial and full-load operation the firing angle is interpolated in each case from a map as a function of the engine speed and the air mass. The full-load firing angle is only accepted when, in addition to the "Full load" engine state, the coolant temperature also exceeds an applicable full-load threshold. If this is not the case, then the firing angle from the partial-load map is also used during full-load operation. In the engine warm-up mode, the firing angle interpolated from the maps can be assigned a firing-angle offset dependent on warm-up.



Function overview of firing angle calculation

Igni

tion/

Ove

rvie

w

File

: zue

_übe

rsic

ht .v

sd

Dat

um: 0

8.08

.200

3

Firi

ng a

ngle

Fi

ring

angl

e

in s

tart

ing

mod

e

Firin

g an

gle

in

idlin

g m

ode

Firin

g an

gle

in

par

tial-l

oad

and

full-

load

mod

e

Engi

ne s

tate

: St

artin

g

Engi

ne s

tate

: Idl

ing

Firin

g-an

gle

reta

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mita

tion

Firin

g-an

gle

adva

nce

limita

tion

Lim

itatio

n En

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spe

ed

Coo

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tem

p.

Engi

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spe

ed

Engi

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tate

TL/

VL

Firin

g an

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war

m-u

p of

fset

Air

mas

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LLBA

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ZW_s

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ZW_T

LVL

ZW_L

L

Electrical Description of EGM


3 Electrical Description of EGM

3.1 System interface overview

3.1.1 Block diagram

Block diagram for electrical description:

Level converter

PC + monitor and printer

COM 1

Hand-held tester

K- wire

Block diagram - overview of interfaces

File: ele_sch.vsd Datum: 29.Okt. 1999

X016

Fan

Vehicle control (FR)

Starter

Battery

Ignition lock TER15, TER 50

CAN

Crankshaft/camshaft sensors

Gas injectors n -

Throttle valve k -

Service switch Start/Stop

ignition

Proportional valves n -

Sensors

Starter

Motorstecker (55-polig)

Vehicle connector (16-pin)



3.1.2 Connector assignment of EGM and ignition modules

Control unit: Male connector, 55-pin ( engine connector )

Pin No. Assignment or Designation On/Off 0 Lambda lean probe IP On 1 TDC Cylinder 1 sensor ( - ) On 2 Crank-angle position sensor ( - ) On 3 Injector F Off 4 Injector E Off 5 Injector D Off 6 P charge air; P oil; exhaust-gas temperature; throttle valve potentiometer -

return On

7 Lambda probe heating LSU (high-side) Off 8 DK_Poti B On 9 P gas; visco; oil level; - return On

10 DK_Poti A On 11 Lambda probe heating LSU (low-side) Off 12 Gas pressure-sensor signal On 13 Oil pressure-sensor signal On 14 Injector C Off 15 Gas-off switching valve (low-side) Off 16 Injector B Off 17 Injector A Off 18 Prop_return switching output 12 Off 19 Crank-angle position sensor ( + ) On 20 TDC Cylinder 1 sensor ( + ) On 21 Lambda lean probe IA On 22 Knock signal 1 On 23 Knock sensor return On 24 Knock signal 2 On 25 Lambda lean-probe signal On 26 Lambda lean-probe virtual ground On 27 P gas; oil level; visco; - supply Off 28 Exhaust-gas temperature signal On 29 Oil level sensor - input On 30 P turbocharging; P oil; DK potent.; LMM; - supply Off 31 Boost-pressure sensor signal On 32 Coolant temperature signal On 33 Charge-air temperature sensor signal On 34 Gas-temperature sensor signal On 35 Oil-temperature sensor signal On 36 Throttle valve (+) Off 37 Service engine switch - start On 38 Starter actuation - high-side * Off 39 Visco_fan speed input On 40 Temp. charge-air/oil/gas/water - return On 41 Service engine switch - supply Off 42 Service engine switch - stop On 43 Supply injection bank 2 Off 44 Ignition 1 Off 45 Ignition 3 Off 46 Ignition 5 Off 47 Supply injection bank 1 Off 48 Ignition 2 Off



Control unit: Male connector, 55-pin ( engine connector )

Pin No. Assignment or Designation On/Off 49 Proportional valve 1 (low-side) Off 50 Proportional valve 2 (low-side) Off 51 Ignition 4 Off 52 Ignition 6 Off 53 Proportional valve 3 * (low-side) Off 54 Throttle valve (-) Off

* : Signal also on vehicle connector

Control unit: male connector, 16-pin ( vehicle connector )

Pin No. Assignment or Designation Abbreviation On/Off 1 CAN interface (high line) CAN_H On/Off 2 CAN interface (low line) CAN_L On/Off 3 CAN - HF Ground HF_GND 4 CAN - HF Ground HF_GND 5 Battery voltage (battery positive) TER30 6 Battery voltage (battery positive) TER30 7 n.c. TDC_Trigger 8 Starting actuation (signal) TER50 On 9 Earth (Battery negative) TER31

10 Proportional valve supply 34 (high-side) Prop_Vers_34 Off 11 Earth (Battery negative) TER31 12 Starter actuation * STARTER Off 13 Diagnosis K line (ISO) DIAG-K On/Off 14 Proportional valve 3 * (low-side) Prop3 Off 15 Battery voltage connected (ignition) TER 15 On 16 Proportional valve 4 (low-side) Prop4 Off

* : Signal also on engine connector

Ignition module: male connector, 5-pin

Pin No. Assignment or Designation Abbreviation On/Off 1 Earth (Battery negative) TER31 2 Signal input for high-voltage output 1 Input 1 On 3 Signal input for high-voltage output 3 Input 3 On 4 Signal input for high-voltage output 5 Input 5 On 5 Battery voltage positive (connected) TER 15



3.1.3 Power supply of EGM

1. Supply voltage

Nominal voltage: 22 V < U < 30 V

Undervoltage: 8 V < U < 22 V limited

operating range

Overvoltage switch-off: U > 32 V

2. Reverse voltage protection, overvoltage

protection

Reverse voltage protection: continuous polarity reversal

of Ter. 30, Ter. 31 without

damage to system

components

Overvoltage resistance: 58 V

4. Power consumption

average power consumption

(ignition on, engine stopped)

0.2 A at U = 27 V

average power consumption

(at engine speed = 500 rpm)

1.7 A at U = 27 V

Peak power consumption

(without proportional output stages)

10 A, cyclical, dependent on

engine speed

5. Power loss

max. power loss: 20 W at 27 V

6. Short-circuit detection thresholds

Gas injector against return line typ. 25 A

Proportional valves against supply typ. 5 A

Prop return12 against supply typ. 10 A

Throttle valve against return line typ. 20 A

Fan supply against earth typ. 15 A

Starter against earth typ. 2.5 A

Lambda heating against return line typ. 3 A

7. Bias power consumption

with Ter. 15 off and after completing run-on I < 1 mA



3.1.4 Power supply of ignition module

1. Supply voltage

Nominal voltage: 9 V < U < 30 V

2. Reverse voltage protection (with connector coding)

Ignition electronics Continuous polarity reversal of supply

connections without damage.

Ignition transformer In case of polarity reversal of supply

connections, short-circuit current flows

through ignition transformer. To prevent

damage to ignition transformer, it must be

limited to max. 7.5 A with external measures.

3. Power consumption

Power consumption of ignition electronics

without energising of ignition output stage

typ. 40 mA

Power consumption of ignition electronics

with energising of ignition output stage

typ. 80 mA

Actuation current via interface

Control-unit ignition module

typ. 10 mA

Primary current of ignition transformer typ. 7.5 A



3.2 Sensor technology

3.2.1 Active sensors

3.2.1.1 Internal control-unit sensors

A pressure sensor is used for comparative measurements of the respective atmospheric pressure (high altitudes).

3.2.1.2 External control-unit sensors

Requirements for sensor inputs for external sensors: Active sensors with an operating voltage of 5 volts are used. These sensors are capable of drawing a sink current through a pull-up resistor toward their 5 volt supply. The sensors may use up to 15 mA of current from the power supply. There are two sensor supplies. These are designed for the connection of up to three sensors each (total current load is max. 45 mA). The current limitation begins at currents greater than 60 mA. Through the output voltage range (0.5 to 4.5 V) of the sensors used, the diagnosability with regard to wiring breaks and short-circuits to earth is ensured. Active sensors are provided for the following input variables. Sensor data: (M447hLaG)

Measured Variable Boost Pressure Gas Pressure (Woodward)

Active Oil Pressure Absolute Pressure

Sensor (Bosch Combi)

Air Mass (not present)

RV in kΩ 10 10 3.6 10 Pressure in kPa 15 284 100 1200 0 500 -- -- Voltage in V 0.22 4.50 0.79 3.98 6 4.5 -- --

3.2.2 Special sensors

3.2.2.1 Throttle-valve position sensors

In modern throttle devices the actuator, throttle valve and throttle valve sensor are integrated in one housing. In the throttle device of the M 447 hLAG a potentiometer is used as a throttle valve sensor. This is supplied by the internal electronics of the throttle device.

3.2.2.2 Lambda probe (Bosch LSU)

To control the air/fuel ratio on the inlet side, a Bosch model LSU broadband lambda probe can be connected to the CNG control unit. Due to its constant characteristic curve in the area λ=0.7 to air, this planar ZrO2 two-cell limit current probe with an integrated heater is suitable both for λ=1 engines and for lean engines. The lambda raw signal is processed with a specific evaluation IC of the probe manufacturer. To compensate production-related sensor tolerances, a trimming resistor is integrated in the connector of the lambda probe.



3.2.3 Passive sensors

Requirement: Temperature sensors based on NTC resistors are used as passive sensors. The voltage drop at the sensor resistor, which is supplied with current by a pull-up resistor, is used for evaluation. These inputs are short-circuit-proof and diagnosable like the active inputs. The following temperatures and pressure are to be detected by the sensors.

3.2.3.1 Temperature sensors

The following information refer to the sensor input circuit. Oil temperature

Temperature sensor data for RV = 1 KΩ ±1.4 °C (at 100 °C) T in °C -40 -20 -5 10 70 90 115 130 U in V 4.9 4.71 4.41 3.96 1.5 0.97 0.56 0.41 RNTC in Ω 49000 16241 7475 3808 429 241 126 89 Coolant temperature

Temperature sensor data RV = 1 KΩ ±1.4 °C (at 100 °C) or ±1.7 °C (at -20 °C) T in °C -40 -20 -5 10 70 90 115 130 U in V 4.9 4.71 4.41 3.96 1.5 0.97 0.56 0.41 RNTC in Ω 49000 16241 7475 3808 429 241 126 89 Charge-air temperature, Beru for 400 series

Temperature sensor data for RV = 2.2 KΩ ±1.5 °C (at 40 °C) T in °C -40 -20 0 35 65 80 105 130 U in V 4.79 4.43 3.61 1.96 0.95 0.64 0.36 0.17 RNTC in Ω 50000 17000 5700 1420 515 324 170 80 Gas temperature, Woodward 400 series

Temperature sensor data for RV = 2.2 KΩ ±1.5 °C (at 40 °C) T in °C -40 -25 0 20 40 70 100 120 U in V 4.89 4.74 4.10 3.02 2.21 0.82 0.39 0.22 RNTC in Ω 100700 40000 10000 3350 1740 430 185 100 Exhaust-gas temperature, Epiq TS-200

Temperature sensor data for RV = 1 KΩ ±20 °C (at 1000 °C) T in °C -40 0 200 400 600 700 800 1000 U in V 0.73 0.84 1.29 1.64 1.91 2.02 2.12 2.3 RNTC in Ω 170 200 349 488 618 679 738 849



3.2.3.2 Camshaft/crankshaft position (inductive)

To detect and evaluate the current crank angle and speed of the engine, one inductive sensor (e.g. VDO) each is used to generate the camshaft and crankshaft signals. Inductive sensor data:

L in mH R in Ω

630 ±15 % 1000.....1385

3.3 Digital inputs

The EGM engine control unit is equipped with the following digital inputs: Terminal 15, Terminal 50 and engine Start/Stop.

3.3.1 Terminal 15

By connecting the Terminal 15 voltage (Terminal 15 ON), the engine control unit is woken up and runs up. This voltage is converted by a comparator into a digital signal and this signal is read in by the processor. The function software of the engine control unit operates using this Terminal 15 signal from the comparator and the Terminal 15 signal which arrives via the CAN bus. The switching thresholds for reliable detection of the Terminal 15 voltage on connector pin 15 of the 16-pin engine connector are:

Control Unit Version Terminal 15 ON Terminal 15 OFF 24 V >11.3 V < 6 V

3.3.2 Terminal 50

With Terminal 50 ON the transponder code for the immobiliser (if installed) is read in and the starter starting signal is output with a valid code. The switching thresholds for reliable detection of the Terminal 50 voltage on connector pin 8 of the 16-pin engine connector are:

Control Unit Version Terminal 50 ON Terminal 50 OFF 24 V > 7.8 V < 2.6 V

The switching threshold for waking up the control unit via Terminal 50 is 9 V.

3.3.3 Service switch Start/Stop

Two digital inputs (short-circuit-proof to earth) are provided which enable the functions Service switch Start and Stop by means of service buttons installed on the engine. An engine start by the Service button is only possible in conjunction with the vehicle electronics, and therefore only in the vehicle. The buttons are supplied with a voltage of approx. 5 V.



Hardware description: The contact current when a button is pressed is approx. 10 mA. In addition, the inputs to the buttons are short-circuit-proof to earth and insensitive to dirt resistances parallel to the buttons. The dirt resistances can have values down to 10 KΩ.

3.4 Actuator technology

3.4.1 Gas injectors

Guide values for Bosch valves CNG 1.3A and for the supply lines Resistance: 4.6 Ω at ± 0.5 Ω at 20 °C Valve current (peak/hold): 2 A/0.5 A Average opening time (8 bar): approx. 2 ms Wiring harness resistance: < 200 mΩ

3.4.2 Gas injector actuation

The gas injector actuation is primarily intended to ensure that the gas injectors open reliably and the fed gas mass is transferred. In contrast to PLD, compliance with an exact start of gas injection only plays a subordinate role. The calculated angle for start of gas delivery is therefore the start of the electrical actuation. This takes place sequentially, both for multipoint and for single-point engines. Hardware and software are designed so that overlapping of actuation is possible. The actuation sequence over time takes place purely controlled, i.e. there is no feedback on the opening state of the valve. For diagnosis purposes and for fast hardware-side output state switch-off, each valve bank is provided with its own current measurement and interrupt triggering.



3.4.2.1 Principle of gas injector actuation

Actuation takes place according to the peak and hold principle with subsequent rapid current switch-off. The actuation phases and the valve current curve are shown in the following illustration. Actuation phases and current curve of gas injectors

Push phase To achieve the pickup current of approx. 2 – 4 A (depending on valve type) as quickly as possible, the battery voltage is connected to the valve with a high PWM pulse duty factor. The push time to be applied is selected so that the desired, typical peak current is set. The actuation frequency is 10 kHz. The valve is already opened before the end of the push phase. Hold phase After the push time expires, the system switches over to the holding mode with an actuation frequency of 5 kHz. The suitable selection of the pulse duty factor in this phase reduces the valve current to the holding current following an e function. The reduced current during the hold phase both decreases the losses in the valve and output stage, and also reduces the duration of the closing process in the switch-off phase. Switch-off phase After the end of the desired gas injection period, the valve switch-off follows so that the magnetic energy in the valve discharges against a 37 V switch-off pulse. The switch-off energy is dissipated by the actuating transistor.

Pick-up

Holding current

Actuation phases of gas injectors

PWM 10kHz Push -Phase

PWM 5kHz Hold-Phase Switch-Off Phase

U(t)

I(t)

t

t

0V

24V

2 - 4 A

0A

(injector-dependent)

(injector-dependent)



3.4.3 Proportional valve actuation

To actuate external actuators and switching devices (e.g. turbocharger, gas pressure regulator, fan etc.), four proportional valve connections are provided in the EGM-C1 sample. The valve current is controlled by means of PWM with intelligent low-side drivers with a diagnostic function, however without current measurement. On the M 447 hLAG only the output Prop 1 boost pressure control is currently used. Data for Prop 1: Valve current: INom = 2 A (over entire temperature range) PWM frequency: fPWM = approx. 120 Hz PWM resolution: < 1% The outputs Prop3 and Prop4 are used for the low-side actuation of various fan systems. On the ÜSTRA natural-gas Citaro the fans are actuated by a separate controller. The outputs Prop3 and Prop4 are not in use.

3.4.4 Lambda heating actuation

The CNG engine control unit permits the connection of a broadband lambda probe, model LSU, for the lambda control. The nominal temperature of the measuring probe is around 750 °C. As the exhaust-gas temperature of natural-gas lean engines is considerably loser, an electrical probe heater is required. According to the manufacturer, these new types of probes, produced in planar technology do not permit charging with a heater voltage of 24 V. Therefore, a switching controller is integrated in the control unit which supplies a low, load-dependent heater voltage of approx. 11 V. The heater current is continuously measured and lies at approx. 1.1 A in the steady state. Data for lambda heater Heater voltage: 11 V ± 0.5 V Heater current: INom = 1.1 A (dependent on exhaust-gas temperature) Min. switch-on duration: 10 ms Resistance: 2Ω < R < 10Ω (dependent on exhaust-gas temperature)

3.4.5 High-pressure cut-off valve actuation

The high-pressure cut-off valve of a natural-gas engine is comparable to the fuel pump of a petrol engine. Through actuation the gas injection system is supplied with fuel. For safety reasons, this valve is supplied by Ter. 15 and energised on the control unit side with low-side actuation. As these valves have a high-resistance design, a switching output state is sufficient. Data for Gas_OFF: Valve current: INom = 2 A (over entire temperature range)

3.4.6 Ignition module actuation

The ignition modules are actuated powerlessly via a six-channel driver output stage. Each channel controls the closing and firing angle of one cylinder. The actuation principle is shown in the following illustration.



The ignition transformer is energised on the primary side when the level changes from low to high on the input of the ignition output stage. The duration of the high phase (closing angle) is map-controlled and determines the peak value of the primary current. The negative signal edge at the input of the ignition output stage switches off the primary current and simultaneously represents the firing point. The closing-angle map must be applied so that the primary current increases up to the nominal value (see drawing 318 974.AZ) without going into the limitation (see illustration of principle of ignition actuation). To protect against continuous energising, the ignition module automatically limits the primary current to approx. 7.5 A and after approx. 100 ms a spark-free output stage switch-off takes place. Continuous operation of the ignition modules in overloading leads to high power loss in the ignition electronics and can ultimately lead to destruction. Principle of ignition actuation:

Control IC

+UBatt

-UBatt

Control unit Ignition output stage Ignition trans.

TER.15

TER.1/6

Input 1/6 Cyl. 1

ZZP ZZP

Closing angle

Ignition actuation principle File: zuend.vsd Datum: 8 Okt, 1999

correct incorrect (high power loss due to limitation)

incorrect (low ignition energy)

Current measurement

Prim

ary

side

t

t

Signal curve during actuation

Inpu

t 1/

6

Prim

ary

curr

ent [

A]

7.5]

Diagnose


4 Diagnosis

4.1 Reading measured values

The following table contains the measured values available for Customer Service via Star diagnosis and via the on-board diagnosis.

No. Process Variable

Resolution Unit

1 Target engine torque (FR) 1.00 Nm 2 Maximum current engine torque 1.00 Nm 3 Actual engine torque (MR) 1.00 Nm 4 Gas injection angle (Cylinder 1) 0.10 °Cranksh. 5 Angle of start of gas injection (Cylinder 1) 0.10 °Cranksh.

before TDC. 6 Current target control speed 1.00 rpm 7 Current final limit speed 1.00 rpm 8 Control-speed target value (FR) 1.00 rpm 9 Redundant speed (Ter. W) (FR) 1.00 rpm 10 Engine speed 1.00 rpm 11 Exhaust-gas temperature 1.00 °C 12 Vehicle speed (FR) 1.00 km/h 13 Coolant temperature 1.00 °C 14 Gas temperature 1.00 °C 15 Gas pressure 1.00 mbar 16 Oil level

0.10 l

17 Oil temperature 1.00 °C 18 Charge-air temperature 1.00 °C 19 Boost pressure 1.00 mbar 20 Atmospheric pressure 1.00 mbar 21 Oil pressure 1.00 mbar 22 Throttle-valve target position 0.10 °Th. valve 23 Throttle-valve actual position 0.10 °Th. valve 24 Lambda target value 0.01 - 25 Lambda actual value 0.01 - 26 Lambda-probe heating current 1.00 mA 27 Lambda correction factor 0.01 - 28 Air mass 1.00 mg/stroke 29 Gas mass 0.10 mg/stroke 30 Firing angle (Cylinder 1) 0.10 °Cranksh.

before TDC 31 Turbocharger pulse duty factor 0.10 % 32 Battery voltage 1.00 mV

Diagnose


4.1.1 Target engine torque (FR)

The vehicle control (FR) interprets the accelerator pedal position and derives the target engine torque (FR). The FR sends this request to the EGM via the CAN bus. The EGM accepts the target torque specification of the FR when the communication between the FR and the EGM functions properly. In case of a complete failure of the CAN communication, the fault code 0104 is entered in the fault memory. If this fault occurs, the MR EGM goes into the so-called "CAN emergency running mode". In the CAN emergency-running mode the CAN target torque specification of the driver is ignored and the engine speed is increased to an idling speed of approx. 900 rpm. Determining the target engine torque

4.1.2 Maximum current engine torque

The maximum current engine torque is equivalent to the full-load torque of the engine as a function of the current engine speed. See the Engine performance data of the individual output variants.

4.1.3 Actual engine torque

The actual engine torque is calculated from a map in dependence on the engine speed and the air mass. This torque is corrected as a function of the actual lambda. If the gas mass is zero, then the engine torque is equivalent to the basic torque (engine drag torque) as a function of the engine speed.

4.1.4 Gas injection angle (Cylinder 1)

The gas injection angle is a functional variable calculated by the EGM based on the gas injection mass and the engine speed. Gas injection begins when the angle for start of gas delivery is reached and is carried out via the gas injection angle.

4.1.5 Angle for start of gas delivery (Cylinder 1)

The angle for the start of gas delivery is an internal process variable calculated by the EGM. The angle of the start of gas delivery characterises the crankshaft angle before ignition TDC at which the cylinder-selective actuation of the gas injectors begins.

Target engine torque (FR) Target torque FR (Request via CAN)

0

CAN error

Title: Service EGM: Diagnosis File: kd_mob_01.vsd Datum der letzten Änderung: 2001-09-13

Diagnose


4.1.6 Current target control speed

Equivalent to the target idling speed or the target operating speed. When the M 447 hLAG is used in buses, no operating speed controllers are required.

4.1.7 Current final limit speed

Final limit speeds are stored in the data record of the MR EGM. The FR can reduce the final limit speed programmed in the MR with a specification via CAN "Current final limit speed", but CANNOT increase it.

4.1.8 Control-speed target value (FR)

During operation with operating speed control, the "Control-speed target value (FR)" is equivalent to the operating speed specification for the operating speed controller. During operation outside the operating speed control, the specification is equivalent to the idling speed. The FR can increase the idling speed within a certain range, but cannot decrease it.

4.1.9 Redundant speed (Ter. W) (FR)

This is another specification of the engine speed. The FR determines the engine speed from the alternator speed and makes this information available to the EGM via the CAN.

4.1.10 Engine speed

This is an engine speed determined by the EGM. The EGM determines this based on the crankshaft/camshaft signal.

Diagnose


4.1.11 Exhaust-gas temperature

The exhaust-gas temperature is calculated every 40 ms. The calculated exhaust-gas temperature is a filtered variable (low-pass filter). If the voltage of the exhaust-gas temperature sensor is above 2.7 V or below 0.3 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 6715 or 6716 is entered. In the case of a fault, a fixed substitute value of –30°°C is output. Exhaust-gas temperature sensing is only possible with control units from hardware version C2. The characteristic curve of the coolant temperature sensor is stored in the engine data record. Characteristic curve: Exhaust-gas temperature sensor

4.1.12 Vehicle speed (FR)

The vehicle speed is determined by the FR and made available to the EGM via CAN. This information is, for example, required for the functions of the overrun fuel cut-off (SAS).

SEN - T exhaust-gas: sensor code Exhaust-gas temperature [°C] = f(Sensor voltage [V])

Exha

ust-

gas

tem

pera

ture

Voltage

Diagnose


4.1.13 Coolant temperature

The coolant temperature is calculated every 40 ms. The calculated coolant temperature is a filtered variable (low-pass filter). If the voltage of the coolant temperature sensor is above 4.97 V or below 0.35 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1515 or 1516 is entered. In the "Engine starting" engine state (starting) the charge-air temperature is used as a substitute value. In the other engine states the substitute value is 92 °C. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, then the last coolant temperature calculated under valid conditions is retained. In the case of a fault, the measured value is sent on the CAN as "Signal not available". The characteristic curve of the coolant temperature sensor is stored in the engine data record. Characteristic curve: Coolant temperature sensor

SEN - T engine: sensor code Coolant temperature [°C] = f(Sensor voltage [V])

Coo

lant

tem

pera

ture

Voltage

Diagnose


4.1.14 Gas temperature

The gas temperature is calculated every 40 ms. The calculated temperature is smoothed with a low-pass filter. The characteristic curve of the gas temperature sensor is stored in the engine data record. If the voltage of the gas temperature sensor is above 4.95 V or below 0.35 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1115 or 1116 is entered. Then the substitute value of 30 °C is used as the gas temperature. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last gas temperature calculated under valid conditions is retained. In the case of a fault, the measured value on the CAN is also set to "Signal not available". Characteristic curve: Gas temperature sensor

SEN - T gas: sensor code Gas temperature [°C] = f(Sensor voltage [V])

Gas

tem

pera

ture

Voltage

Diagnose


4.1.15 Calculation of gas pressure

The gas pressure is calculated every 10 ms. The calculated pressure is smoothed with a low-pass filter. The characteristic curve of the gas pressure sensor integrated in the engine control unit is stored in the control unit software. If the voltage of the gas pressure sensor is above 4.95 V or below 0.67 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1715 or 1716 is entered. Then the substitute value of 8.5 bar is used as the gas pressure. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last gas pressure calculated under valid conditions is retained. Characteristic curve: Gas pressure sensor

SEN - P gas: sensor code (Gas pressure = f(voltage) Gas pressure [bar] = f(Sensor voltage [V])

Pres

sure

Voltage

Diagnose


4.1.16 Calculation of engine oil level

Oil level sensing is currently NOT offered on the M 447 hLAG gas engine and is deactivated. The oil level, top-up quantity and oil level warnings are set to "Signal not available" (s.n.a. = 102 % or -12.8 l) with the sensing function switched off.

4.1.17 Oil temperature

The oil temperature is calculated every 40 ms. The calculated temperature is smoothed with a low-pass filter. The characteristic curve of the oil temperature sensor is stored in the engine data record. If the voltage of the oil temperature sensor is above 4.97 V or below 0.10 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault codes 1015 and 1016 are entered. The substitute value of 85 °C is then used as the oil temperature. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last oil temperature calculated under valid conditions is retained. In the case of a fault, the measured value on the CAN is set to "Signal not available". Characteristic curve: Oil temperature sensor

SEN - T oil: sensor code Oil temperature [°C] = f(Sensor voltage [V])

Oil

tem

pera

ture

Voltage

Diagnose


4.1.18 Charge-air temperature

The charge-air temperature is calculated every 40 ms. The calculated temperature is smoothed with a low-pass filter. The characteristic curve of the charge-air temperature sensor is stored in the engine data record. If the voltage of the charge-air temperature sensor is above 4.95 V or below 0.20 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1215 or 1216 is entered. The substitute value of 40 °C is then used as the charge-air temperature. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last charge-air temperature calculated under valid conditions is retained. In the case of a fault, both the measured value of the charge-air temperature and the air mass calculated from it are set on the CAN to "Signal not available". Characteristic curve: Charge-air temperature sensor

SEN - T charge-air: sensor code Charge-air temperature [°C] = f(Sensor voltage [V])

Cah

rge

air t

empe

ratu

re

Voltage

Diagnose


4.1.19 Boost pressure

The boost pressure signal is read out and standardised in the 1 ms time slice. The calculated pressure is then filtered every 10 ms time synchronised. The characteristic curve of the boost pressure sensor is stored in the engine data record. If the voltage of the boost pressure sensor is above 4.90 V or below 0.24 V for more than 2 seconds, then the event "Measuring range exceeded or dropped below" is detected and the fault code 1415 or 1416 is set. If these faults occur, the EGM switches into the Engine protection: boost-pressure substitute value formation and calculates a substitute value for the boost pressure. In addition, the plausibility of the boost pressure sensor in the "Engine stopped" engine state is checked with the signal of the atmospheric pressure sensor. With the engine at a standstill, the boost pressure and atmospheric pressure must be approximately equal. If the pressure difference of both sensors is greater than 100 mbar for at least 5 seconds, then the event "Measured value implausible" is detected and the fault code 1417 is entered. The test only takes place when both the boost pressure and the atmospheric pressure sensor show no fault electrically and the engine is stopped. In the case of an implausible boost pressure, the engine remains largely available. The monitoring of the lambda correction factor is cancelled and the engine continues to be operated with lambda control. Characteristic curve: Boost pressure sensor

SEN - P charge air: sensor code Charge air pressure [bar] = f(Sensor voltage [V])

Cha

rge

air p

ress

ure

Voltage

Diagnose


4.1.20 Atmospheric air pressure

The atmospheric air pressure is calculated every 40 ms. The calculated pressure is smoothed with a low-pass filter. The characteristic curve of the atmospheric pressure sensor integrated in the engine control unit is stored in the control unit software. If the voltage of the atmospheric pressure sensor is above 4.75 V or below 2.30 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1315 or 1316 is entered. A substitute value of 950 mbar is used as the atmospheric air pressure. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last atmospheric pressure calculated under valid conditions is retained. Characteristic curve: Atmospheric pressure sensor

SEN - P atmosphere: sensor code Atmospheric pressure [bar] = f(Sensor voltage [V])

Atm

osph

eric

pre

ssur

e

Voltage

Diagnose


4.1.21 Oil pressure

The oil pressure is calculated every 10 ms. The calculated pressure is smoothed with a low-pass filter. The characteristic curve of the oil pressure sensor integrated in the engine control unit is stored in the control unit software. If the voltage of the oil pressure sensor is above 4.92 V or below 0.25 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 1615 or 1616 is entered. A substitute value of 3.1 bar is used as the oil pressure. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last atmospheric pressure calculated under valid conditions is retained. In addition, the plausibility of the oil pressure sensor in the "Engine stopped" engine state is checked with the signal of the atmospheric pressure sensor. With the engine at a standstill, the oil pressure and atmospheric pressure must be approximately equal. If the pressure difference of both sensors is greater than 100 mbar for at least 2 seconds, then the event "Oil pressure sensor: Signal implausible" is detected and the fault code 1617 is entered. The test only takes place when both the oil pressure sensor and the atmospheric pressure sensor show no fault electrically and the engine is stopped. The fault code is only an indicator – no measures are taken as the result of this event. In the case of an implausible oil pressure, the oil temperature is also classified as defective and the substitute value is set (combination pressure/temperature sensor). Characteristic curve: Oil pressure sensor

SEN - P oil (active, absolute): sensor code Oil pressure [bar] = f(Sensor voltage [V])

Oil

pres

sure

Voltage

Diagnose


4.1.22 Throttle-valve target position

The throttle-valve target position is a function variable calculated by the EGM in dependence on the target torque specification and the engine speed, and is transferred to the throttle valve actuator as the target specification in the form of a PWM signal ( see Throttle valve control).

4.1.23 Throttle-valve actual position

The throttle-valve actual position is carried out in the 1 ms time slice. The calculated throttle-valve actual position is smoothed with a low-pass filter. The characteristic curve of the throttle-valve position sensor is stored in the engine control unit. If the voltage of the throttle-valve position sensor is above 4.70 V or below 0.30 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 8115 or 8116 is entered. This is only an indicator – the EGM does not take any actions based on these events.

4.1.24 Lambda target value

The lambda target value is a function variable calculated by the EGM in dependence on the target torque specification and the engine speed.

4.1.25 Lambda actual value

The gas lambda actual value is calculated every 10 ms. The calculated lambda actual value is smoothed with a low-pass filter. The characteristic curve of the lambda probe is stored in the control unit software. If the voltage of the lambda signal is above 4.90 V or below 0.15 V for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the fault code 0915 or 0916 is entered. A substitute value of one is used as the lambda actual value. If the fault debouncing time has not yet expired, however the voltage value is outside the limits, the last lambda actual value calculated under valid conditions is retained.

4.1.26 Lambda-probe heating current

The lambda-probe heating current is calculated every 10 ms and is based on an internal voltage measurement in the control unit. The measured voltage permits conclusions to be drawn on the probe current and can NOT be checked outside the control unit. The characteristic conversion curve is stored in the control unit software. The calculated lambda-probe heating current is smoothed with a low-pass filter. The "Lambda-probe heating current" calculated by the MR EGM can be checked by connecting the current tester to the probe heater in series. The "Lambda-probe heating current" is continuously monitored by the EGM. • The MR EGM detects the event "Measuring range exceeded" (fault code 8415) when high currents

(significantly higher than 3 A) are observed by the MR. Possible causes can be a defect in the probe heating or a short-circuit to earth in the wiring. The MR EGM detects the event "Measuring range dropped below" (fault code 8416) when a defect in the probe heating or a break in the wiring is present.

• The MR EGM detects the event "Measuring range dropped below" (fault code 8416) when a defect in

the probe heating or a break in the wiring is present. The MR EGM detects the event "Measuring range dropped below" (fault code 8416) when a defect in the probe heating or a break in the wiring is present.

Diagnose


• The MR EGM detects the event "Measuring range implausible“ (fault code 8417) when the "Lambda-probe heating current" is less than 0.8 A or greater than 1.80 A for at least 5 seconds following the heat-up phase. In case of a fault, the Engine protection: lambda lean-controller probe becomes active.

4.1.27 Lambda correction factor

The lambda correction factor is a function variable calculated by the EGM. This variable is calculated in the lambda controller function block primarily from the variables target lambda and the measured actual lambda. The lambda correction factor is a very significant variable for the lambda-controlled lean engine. For a warm engine this should be approx. ± 5 % in stationary operating points. A positive lambda correction factor means that – always starting from the target lambda dependent on the operating point – the combustion is too lean so that the engine control must inject gas as a reaction. Conversely, a negative lambda correction factor means that the combustion is too rich, i.e. too much gas is injected (possible indication of defective gas injectors or faulty air mass detection).

4.1.28 Air mass

The air mass is calculated from a map as a function of the boost pressure and the engine speed taking the charge-air temperature and target lambda into account.

4.1.29 Gas mass

The gas mass is a function variable calculated by the EGM based on the previously calculated air mass. The calculated gas mass is injected into the intake manifold by means of corresponding actuation of the gas injectors.

4.1.30 Firing angle (Cylinder 1)

Firing angle in °Crankshaft before ignition TDC of the first cylinder.

4.1.31 Turbocharger pulse duty factor

The pulse duty factor with which the electropneumatic converter of the wastegate is actuated.

4.1.32 Battery voltage

The supply voltage of the engine control unit is calculated every 10 ms. The calculated voltage is smoothed with a low-pass filter. The supply voltage of the control unit is checked for the specified limits. If a limit is exceeded or dropped below, a fault is entered in the fault memory after the fault debouncing time expires. Checking for undervoltage is not carried out during starting, i.e. the starter is actuated by the engine control unit or in the "Starting" engine state.

Diagnose


4.2 Reading binary values

No. (dec.)

Information Bit Coding Remarks

1 Engine state Idling Partial load Full-load

1,0 3,2 5,4 7,6

00 = Engine stopped 01 = Engine starting 10 = Normal operation 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a.

see Engine state detection the M 447 hLAG is NEVER in the full-load engine state (ONLY idling and partial load)

2 Warning buzzer

Stop lamp CAN status L line CAN status H line

1,0 3,2 5,4 7,6

00 = not requested 01 = requested 10 = n.d. 11 = s.n.a. 00 = not requested 01 = requested 10 = n.d. 11 = s.n.a. 00 = no communication 01 = communication 10 = n.d. 11 = s.n.a. 00 = no communication 01 = communication 10 = n.d. 11 = s.n.a.

with CAN two-wire operation: Bit 5.4 = 01 Bit 7,6 = 01

3 Status Ter. 15 (EGM)

Info Ter. 15 (FR) Status Ter. 50 (EGM) Status Ter. 50 (FR)

1,0 3,2 5,4 7,6

00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a.

Hardware input Ter.15

Diagnose


No. (dec.)


4 Start button on engine Stop button on engine EGM starter actuation CNG starting interlock

1,0 3,2 5,4 7,6

00 = not actuated 01 = actuated 10 = n.d. 11 = s.n.a. 00 = not actuated 01 = actuated 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = n.d. 11 = s.n.a. 00 = not active 01 = active 10 = Interlock time running 11 = s.n.a.

5 Status PV 1

Status PV 2 Status PV 3 Status PV 4

1,0 3,2 5,4 7,6


On natural-gas Citaro only PV 1. This controls the EPW of the wastegate (ATL) No use on natural-gas Citaro No use on natural-gas Citaro No use on natural-gas Citaro

7 Torque limitation with:

Engine protection End limitation Soft speed limitation Hard speed limitation

1,0 3,2 5,4 7,6


Diagnose


No. (dec.)


8 Cut-off valve state

1,0

00 = CLOSED 01 = OPEN 10 = n.d. 11 = s.n.a.

n.d. = not defined s.n.a. = signal not available n.f. = still free

Diagnose


4.3 EGM-specific Customer Service routines

Special routines have been realised for simplified handling or troubleshooting on the M 447 hLAG natural-gas engine which can be carried out with the customer service tool "StarDiagnosis".

4.3.1 Temporarily switch off LMR

The M 447 hLAG is a lean engine. The lambda probe is a lean probe from Bosch with a measuring range between 0.7 and 1.9. Normally, the lambda controller works in fired operation. A very significant output variable of the lambda controller is the Lambda correction factor . The lambda correction factor is monitored by the EGM (Lambda control diagnosis). In the case of a fault, the event: "Mixture formation: control deviation too great" is detected, the fault code 0775 is stored in the fault memory and the corresponding engine protection is activated. The fault code 0775 means that a serious fault is present in the mixture forming system – however, it does not provide any localising information on possible fault causes. Possible causes of this fault may be: • Fault in mixture formation

- Mechanical defect of one or several gas injectors ( gas injector sticks open, gas injector does not open correctly, leaks on injector block etc.)

- Failure of ignition on one or several cylinders ( mixture leaning due to excess oxygen) - Faulty signal of boost pressure sensor ( faulty air mass detection with the consequence of

incorrect gas mass calculation) - Faulty signal of gas pressure sensor ( faulty gas-injection time calculation)

• Fault in lambda determination

- Faulty signal of lambda sensor ( unmetered air in exhaust section, defective probe etc.) The Customer Service routine: "Temporarily switch off LMR" can help localise the fault source with regard to mixture formation OR lambda determination. The Customer Service routine "Temporarily switch off LMR" enables the lambda controller to be switched off for a limited time. The engine then runs controlled and without power restrictions – the lambda measurement continues to be taken. If the engine runs properly in controlled operation, then this is a sure sign that the engine malfunction results from faulty determination of the actual lambda. In the opposite case, the fault must be sought in the mixture formation system. Notes: - The lambda controller can be switched off and on again with StarDiagnosis. - The lambda controller can only be switched off temporarily, i.e. the lambda controller is switched off

for a maximum period of 10 min. or until the ignition is switched off.

Diagnose


4.3.2 Switch-off of gas injectors

The Customer Service routine: "Switch-off of gas injectors" enables any desired pair of gas injectors to be switched off briefly in order, for example, to investigate the suspicion of incorrectly operating gas injectors. Experience shows that the lambda correction factor changes by approx. 0.15 – when an intact pair of gas injectors is switched off. By switching the individual pairs of gas injectors off and then on again while simultaneously observing the lambda correction factor, the proper operation of the gas injectors can be verified. Notes: - Individual injector pairs can be switched off with StarDiagnosis. - Switch-on conditions for this Customer Service routine are:

- engine state: idling and - dual ignition NOT active

- Only one pair of gas injectors can be switched off at any given time. - The gas injectors are only switched off temporarily; if these are not reset by Customer Service, then

they will automatically be deactivated after 10 minutes or by switching off Ter. 15.

4.3.3 Cylinder-selective ignition switch-off

The Customer Service routine: "Cylinder-selective ignition switch-off" enables the ignition of any desired cylinder to be switched off briefly in order, for example, to investigate the suspicion of firing failures. When the ignition of a cylinder is switched off, engine running must worsen – unless the cylinder already failed to fire beforehand. With the aid of the Customer Service routine it may be possible to localise the ignition failure on a cylinder. The cause of the failure must then be examined on both the primary and the secondary side – beginning with checking the actuation of the ignition modules by the MR via the ignition modules themselves up to compression testing of the individual cylinders. Notes: - The ignition of Individual cylinders can be switched off with StarDiagnosis. - Switch-on conditions for this function are:

- engine state: idling and - dual ignition not active

- The ignition can only be switched off on one cylinder at any given time. - The cylinder-selective switch-off of the ignition is only temporary; if these are not reset by Customer

Service, then they will automatically be deactivated after 10 minutes or by switching off Ter. 15.

Diagnose


4.3.4 Temporarily switch off engine run-on

The M 447 hLAG is switched off with the so-called "Engine run-on" . This means that when Ter. 15 is switched off, the high and low-pressure cut-off valve are switched off (gas supply switched off), however the gas injection and ignition continue to run so that the engine continues running until the gas in the low-pressure line is consumed (to protect the catalyst) and the engine dies due to a shortage of gas. After the gas in the low-pressure line is used up, the pressure in the injector block drops to approx. 1 to 2 bar. When the following Customer Service routine activated: "Temporarily switch off engine run-on", the gas injection is immediately stopped and the gas cut-off valves are closed after Ter. 15 is switched off. If the gas injectors are "tight", then the gas pressure in the injector block is approx. 8 bar. A leak test of the gas injectors can be carried out in this way. Notes: - The engine run-on can be switched off once by starting the routine "Switch off engine run-on"

(repeatable!) - Deactivation of the function with Ter. 15 off and control unit run-on ended!

4.3.5 Manual compression test

The Customer Service routine: "Manual compression test" is an auxiliary function when conducting a manual compression measurement. This routine can be activated with Star-Diagnosis. The activation of this Customer Service routine results in: - the gas injection being switched off by

– the gas mass being set to zero and no actuation of the gas injectors being carried out, – the gas cut-off valves being switched off (closed)

- the actuation of the ignition being switched off - the throttle valve being opened (throttle valve position = 80 °DK) Notes: - This Customer Service routine can only be deactivated by switching off Ter. 15 - The function the only be activated when

– the throttle-valve reverence movement has failed – a short-circuit to earth of the gas injectors is detected – the engine dwells in the "Starting" or "Normal" state

Checking EGM _____________________________________________________________________


5 Checking EGM

5.1 Troubleshooting

The internal fault diagnosis is generally an important aid for troubleshooting so that the fault memory content should always be checked at the start of troubleshooting.

5.1.1 Engine fails to start

Possible causes:

5.1.2 Engine cannot be switched off

Possible causes:

5.1.3 Increased engine idling speed

Possible causes:

Checking EGM _____________________________________________________________________


5.1.4 Reduced engine output

Possible causes:

5.1.5 Rough engine running, traction interruption

Possible causes:

Checking EGM _____________________________________________________________________


5.2 Special tools

Condition for testing: • Battery voltage 24 volts • Brake pressure at least 8.5 bar • Spark-plug spanner (w/f 16) • Stroboscopic lamp • Socket box for 55-pin engine connector • Current probe • Oscilloscope (with at least two channels)

5.3 Circuit diagram of M 447 hLAG

Checking EGM _____________________________________________________________________


Remove page in hand-out and replace with a copy of the wiring harness diagram!!!

Checking EGM _____________________________________________________________________


5.4 Engine performance data

Performance graph for O 447 hLAG, 240 kW

Performance graph for M 447 hLAG, 185 kW

M447hLAG - 240 kW at 2000 rpm / 1250 Nm at 1500 rpm

0

200

400

600

800

1000

1200

1400

600 800 1000 1200 1400 1600 1800 2000 2200

0

40

80

120

160

200

240

280

Torque [Nm] Power [kW]

Pow

er [k

W]

Torq

ue [N

m]

Speed [rpm]

M447hLAG - 185 kW at 2000 rpm / 1050 Nm at 1300 rpm

0

200

400

600

800

1000

1200

600 800 1000 1200 1400 1600 1800 2000 2200

Drehzahl [min-1]

0

40

80

120

160

200

240

Torque [Nm] Power [kW]

Pow

er [k

W]

Torq

ue [N

m]

Speed [rpm]

Checking EGM _____________________________________________________________________


5.5 Safety precautions when working on EGM

The following safety precautions must always be observed to prevent damage to the engine components or wiring harness and to avoid endangering persons! • Never start the engine without the battery being firmly connected (battery terminals firmly

connected).

• Do not disconnect batteries from the vehicle electrical system with the engine running.

• False polarity of the control unit supply (e.g. false polarity of the batteries) can lead to the control unit being destroyed.

• Do not use quick chargers to start the engine. Only carry out auxiliary starting with separate batteries.

• To quick-charge the batteries, they must be disconnected from the vehicle electrical system.

• The control unit connector may only be disconnected or connected with the electrical system switched off (Ter. 15 OFF).

• The lambda probe connector may only be disconnected or connected with the electrical system switched off (Ter. 15 OFF).

Appendix _____________________________________________________________________


6 Appendix

6.1 Pulse width modulated signal

Many actuators around the EGM are actuated with a PWM signal. The PWM signal is characterised by the frequency f and the pulse duty factor TV. An example of such actuators are: - Gas injectors - Proportional valves (EPW for actuating the ATL) - etc. Drawing: pulse width modulated signal

Title: Service EGM: Engine protection File: KD_PWM_Definition.vsd Datum der letzten Änderung: 2001-09-14

PWM / Pulse width modulated signal

T_high T_low

Period duration T

1 f =

T

Pulse duty factor TV = T_high T

Appendix _____________________________________________________________________


6.2 Overview of bus systems (EvoBus)

Great importance is rightly ascribed to the MR EGM, however it is only one of a large number of control units in the interconnected system of the natural-gas CITARO (the interconnected system of the natural-gas CITARO is identical to and completely compatible with the series-production model, for example as on the diesel CITARO). Overview of bus systems (EvoBus) Overview of Bus Systems

CAN bus ”I panel“

CAN bus ”K line“

Onboard diagnosis

CAN bus ”Vehicle“

Central lubrication

Door 1 MTS

Door 2

Door 3

Index _____________________________________________________________________


7 Index

A Air mass 67 Atmospheric air pressure 64

B Battery voltage 67 Boost pressure 63

C Circuit diagram 76 Customer Service routine

temporarily switch off engine run-on 73 Customer Service routines

manual compression test 73 Customer Service routines

cylinder-selective ignition switch-off 72 cylinder-selective switch-off of gas injection

72 temporarily switch off LMR 71

E Engine protection

boost-pressure substitute value formation 14, 18, 63

camshaft emergency-running mode 14, 19, 20

charge-air temperature 14, 15 coolant temperature 14, 16 dual ignition 14, 19 exhaust-gas temperature 15, 25 gas injection 14, 22 ignition 14, 23 lambda lean-controller probe 14, 21, 38, 67 oil pressure 14, 24 overspeed 14, 25, 30 turbocharger overpressure 14, 17

Engine run-on 73

F Fault code

0104 55 0775 21, 38, 71 0915 66 0916 66 1015 61 1016 61 1115 59 1116 59

1215 62 1216 62 1315 64 1316 64 1415 18, 63 1416 18, 63 1417 63 1515 58 1516 58 1615 65 1616 65 1617 65 1715 60 1716 60 1818 34 1820 17 2122 16 4209 22 4279 22 4309 22 4379 22 4409 22 4479 22 4509 22 4579 22 4609 22 4679 22 4709 22 4779 22 4808 22 4809 22 4908 22 4909 22 5806 23 5807 23 5809 23 5906 23 5907 23 5909 23 6006 23 6007 23 6009 23 6106 23 6107 23 6109 23 6206 23 6207 23 6209 23 6306 23 6307 23 6309 23 6715 57 6716 57

Index _____________________________________________________________________


8115 66 8116 66 8374 30 8415 66 8416 66 8417 21, 67

Firing angle (Cylinder 1) 67

G Gas mass 67

L Lambda actual value 66 Lambda correction factor 67, 71 Lambda target value 66 Lambda-probe heating current 66

O Oil pressure 65

Overview of bus systems (EvoBus) 81

P Performance data 55, 78

185 KW 78 240 KW 55, 78

PWM signal 80

S Safety precautions 79 Special tools 76 System synchronisation 19

T Throttle valve control 29 Throttle-valve actual position 66 Throttle-valve target position 66 Turbocharger pulse duty factor 67

Documents

Natural Gas Engine: M 447 hLAG In Mercedes-Benz … Manual (Omnibus Model O 530 ... (Antilock Braking System) ... PLD Pumpe-Leitung-Düse (Pump Line Nozzle