Shaping the Future Engine Management Systems and Calibration

Shaping the Future

Engine Management Systems and Calibration

Engine Management Systems

The basic role of an Engine Management System is to provide precise control of engine operation by managing fuel supply, ignition, and the quantity of air inducted into the engine

At the heart of every Engine Management System is an electronic control module (ECM), which is an on-board computer incorporating a digital microprocessor.

The ECM is linked to the engine by means of sensors installed on the engine (to read data about the operating conditions of the engine), and actuators such as ignition coils, stepper motors, relays, etc as the means for effecting control on engine operation.

The modern EMS also has to provide a comprehensive level of self-diagnosis in the case of faulty components or engine operation. This is referred to as On-Board Diagnostics (OBD).

Engine Management Systems

Engine Control Module (ECM)

Sensors

Actuators

Engine Management Systems Early EMS

ECMFuel Tank

Fuel Pump

Distributor Based Spark

Ignition Port Fuel Injector

Cold Start Injector

Idle Speed By-Pass

Gate – Air Mass Flow Meter

Throttle Position Sensor

Bosch L-Jetronic

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Engine Management Systems

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Engine Management Systems

Bosch Motronic MED EMS (Direct Petrol Injection)

Engine Management Systems

Wide Band – Linear Lambda Sensor

Typical Functions of an EMS

Spark Advance Control (with or without Waste Spark)Knock Control through Adaptive Spark AdvanceIdle Speed ControlIndependent Cylinder Fuel Injection (inc Multi Strike)Exhaust Gas Recirculation ControlAdaptation for Alternative FuelsCharcoal Canister Purge ControlCam Phasing and Valve LiftVariable Geometry Turbocharging and Intake SystemsFull Diagnostics (compliance with OBD legislation) Cylinder Disablement for torque controlEngine Temperature Management

Main Components of an EMS

Electronic Control Module (ECM)Crankshaft Speed SensorCamshaft Position SensorFuel PumpFuel InjectorsFuel Pressure RegulatorAir Mass Flow Meter Manifold Absolute Pressure SensorThrottle Position SensorThrottle Actuator Exhaust Gas Recirculation ValveIdle Speed Air By-Pass ValveExhaust Gas Oxygen Sensor Ignition CoilSpark Plug

Sensors and Actuators

Sensors - Speed & Position

Variable Reluctance Crankshaft Speed Sensor

Hall Effect Camshaft Position Sensor

A voltage is generated transversely (between points E and F) to the direction of current flow (A to B) if a magnetic field is applied perpendicularly to the conductor. (usually a

semiconductor)

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Air Mass Flow Meter

Sensors – Mass Air Flow

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Oxygen or Lambda Sensor

Sensors – Oxygen Sensor

Engine Control Module (ECM)

Delphi MT80 Control Module

EMS Control Overview Fundamentally the Engine Management System (EMS) attempts to control the highly complex thermodynamic functions that define the continuously varying engine operating conditions, by providing the right quantities of air, fuel, timing of ignition, exhaust gas recirculation etc.

A theoretical approach to this problem would be to incorporate a complex set of mathematical models or algorithms that define every possible condition. The EMS would then only have to run these models in real time to correctly supply the desired fuel, air, egr and ignition advance.

Algorithms used in the EMS are models that describe the operation of a particular function for given values of input data but also use some previously determined empirical data (maps)

An EMS will have a wide range of relatively simple models (also known as strategies) for specific control functions

Engine Speed Engine Load(Throttle Position or Manifold Absolute Pressure)

Fuel Injection Quantity (milligrams) or Pulse Width (millisecs)

EMS Control Overview

Data from Sensors

Instructions to Actuators

Structured 2-D and 3-D Maps or “Look Up Tables” (Maps) and algorithms (“Strategy”)

EMS Control Overview

Spark Advance Control (with or without Waste Spark)Knock Control through Adaptive Spark AdvanceIdle Speed ControlIndependent Cylinder Fuel Injection (inc Multi Strike)Exhaust Gas Recirculation ControlAdaptation for Alternative FuelsCharcoal Canister Purge ControlCam Phasing and Valve LiftVariable Geometry Turbocharging and Intake SystemsFull Diagnostics (compliance with OBD legislation) Cylinder Disablement for torque controlEngine Temperature Management

EMS Control Strategies

EMS Strategy ExampleIdle Speed Control

Idle speed variation is caused by; Changes in auxiliary power take off requirements, for example air

compressors and alternators. Combustion performance variability (eg COV of IMEP) Driver input – “blipping the throttle”

The task of the idle speed control system is to primarily manage the step torque demands of the auxiliary systems through air flow

control and ensure that the idle speed is kept as low as possible

EMS Strategy ExampleIdle Speed Control

Dynamic Control LoopsEnergy conversion

Intake manifoldTorque balance

InputsEngine SpeedEngine Load

(Man Abs Press)

OutputsAir mass flow

modulator

Plant Model(algorithms & maps)

EMS Strategy ExampleIdle Speed Control Dynamic Control Loops

Energy conversionIntake manifoldTorque balance

InputsEngine SpeedEngine Load

(Man Abs Press)

OutputsAir mass flow

modulator

Plant Model(algorithms & maps)

Intake air flow rate Engine Torque

Engine Speed

Engine Friction Load

Man Press

Air Manifold Pressure

EMS Strategy ExampleIdle Speed Control

Manifold Pressure

Engine Speed

Manifold Air Mass Outflow Estimation (Map)

Manifold Air Mass Inflow dpm /dt = (1/) dmin/dt – dm*out/dt

Integrator

EMS Strategy ExampleIdle Speed Control

Combustion Torque Pulse per Cylinder

(Map)

Torque Delay due to cylinder firing order (dead time & lag)

2J (dn/dt) = Tcomb - Tload

Man Press

Engine Speed Engine

SpeedIntegrator

EMS Strategy ExampleIdle Speed Control Dynamic Control Loops

Energy conversionIntake manifoldTorque balance

InputsEngine SpeedEngine Load

(Man Abs Press)

OutputsAir mass flow

modulator

Plant Model(algorithms & maps)

Air Mass Flow

Modulator Proportional & Integral Controllers

Engine Calibration

Term coined in late 1980s

The precise measurement and optimisation of the characteristics of an engine and drive train in all possible vehicle model variants

A Calibration Engineer instigates the measurement of the engine characteristics and subsequently decides which are the optimum

The Engineer includes the optimum values within the engine EMS

Calibration

“The process of determining the calibre

of a gun”

Typical Calibration Programme

Initial calibrations based on previous experienceTesting of prototype engines on an engine dynamometerCalibration transferred to vehicle for refinementSuccessive approximationsHomologationFinal Calibration ValidationSold to production+90 days support

2 to

3 Y

ears

“Tools of the Trade” Engine Test Cell Vehicle Chassis Dynamometer Linear AFR sensor Measurement & Calibration (Interface) System Automated Calibration System Cold and Hot chambers

(and/or equivalent ambients) Emissions Lab Test Track Analysis tools

ExcelMatlab SimulinkModel Based Calibration toolbox

Measurement & Calibration System

ECU Description Data

ECU Program Data

Calibration Data

Auto Calibration System

Measurement and Calibration

System

ECU

Engine Actuators

Sensors

Master Slave

Low Level Commands, Data and On-Line Values

Commands, Data and On-Line Values

Serial Communication Serial Link (CAN or K-Line)

RS 232

e.g. ATI Vision e.g. AVL CAMEO

MCS Calibration Tool – ATI Vision

MCS Calibration Tool – ATI Vision

Engine Speed

Thro

ttle

Pos

ition

Lambda

MCS Calibration Tool – ATI Vision

Automated Calibration – AVL Cameo

Optimises Engine Testing using Design of Experiments Models to gather data for EMS Maps

Thank You for Listening