Presentation on Electronic Control Unit (ECU)

By :-Vinayak Naik (0415077)Vishal Prajapati (0415092)Jayneel Pandya(0415083)Suyog Powle(0415091)

Introduction In automotive electronics, an electronic control unit (ECU), also called a

control unit or control module, is an embedded system that controls one or more of the electrical subsystems in a vehicle.

Some modern cars have up to 70 ECUs, including:

• Engine Control Unit

• Transmission Control Unit

• Telephone Control Unit

• Man Machine Interface

• Door Control Unit

• Seat Control Unit

• Climate Control Unit

• speed control Unit

Major Operations Performed By ECU

Control of fuel injection. Control of ignition timing. Control of variable valve timing. Control of starting.

Electronic Control Module Computer/ECM

Controls spark timing, fuel delivery and emission controls. Continuously receives signals from sensors and input devices on or near the engine; sends control signals to valves, controllers and other output devices. Stores "trouble codes" and warns driver when service is needed.

ECM and Its Functions It is also called as the ECU ,microprocessor , controller etc. The ECM serves as the processor or decision maker in an ECU. The two main parts of the ECM are the IC chips & the memory.

The functions of ECM : It receives signals. It processes signals. It makes decisions. It sends commands that control other engine components .

ECU Block Diagram

ECU BLOCK Engine speed sensor / Engine speed correction (ES & EC) - The ES

stage determines engine speed using pulse data from the PL. The EC stage corrects the mixture for engine speed (volumetric efficiency), using the output of the ES.

Fuel pump control (FPC) - Controls the FPR using inputs from Start and the ES.

Pressure-sensing loop (PL) - Creates the basic injection pulse using inputs from the TS1, MPS, IM, and SC. The TL supplies the injection timing signal for injection pulse initiation and synchronization

Idle mixture adjustment (IM) - Adjusts the mixture at idle using inputs from the IS and IA. The IA is not present on early ECU's.

Idle-cold mixture compensation (ICM) - Adjusts the mixture for cold start, and provides partial idle mixture control using inputs from Start .

Over-run shutoff (OS) - Shuts off injection on overrun, using inputs from the PL and IS. Not present on all ECU's.

ECU BLOCK  Pulse width multiplier (PWM) - Delays and stretches the basic injection

pulse duration using inputs from the ES, FC, AE, and CTC. Cylinder temperature compensation (CTC) - Adjusts the mixture for

cylinder head temperature using inputs from TS2 and ICM. Injection logic (IL) - Combines inputs from the FC, PWM, and AE to create

the final injection pulse. Acceleration enrichment (AE) - Provides immediate and delayed

acceleration enrichment using input from the TPS. Switching logic (SL) - Routes the final injection pulse to the correct injector

group using inputs from the IL and TL. Timing logic (TL) - Creates group injection gate pulses and injection timing

signal using input from the TC. Output driver stages (D1, D2) - Converts the final injection pulse for each

injection group to the proper level to drive the injectors I1-4.

ECU Operation Overview Electronic Control Unit (ECU) controls most aspects of the fuel injection system. Also known as a "brain" or a "computer ". It's a combination of digital circuits, analog sensor interfaces, and control circuits. The ECU controls the timing and duration of voltage pulses to the injectors, and the operation of the fuel pump relay (FPR). The operation of the cold start valve (CSV) is independently controlled by the thermo- or thermo-time switch (TS), not the ECU. The ECU determines the timing and duration of the injection pulses by processing signals from the ignition start switch(Start), trigger contacts(TC) , manifold pressure sensor(MPS), temperature sensors(TS1 - air temp, and TS2 - cylinder head temp), and throttle position switch (TPS w/ idle switch IS). The ECU controls the operation of the FPR by processing signals from Start and the TC.

ECU Operation OverviewThe timing of injection pulses is determined by signals from the TC. In 4-cylinder , the injectors are paired and pulsed together - this is called "group injection". Determination of the injector pulse duration (Ti) is fairly complex, there is a basic injection pulse duration (Tb) for a specific engine load to achieve a target air/fuel ratio.Engine load is determined by measuring the intake manifold pressure with the MPS. Ti is also affected by specific operating conditions - cold start, engine speed, idle, part-load, full-load, cold/warm/hot engine, acceleration, and air temperature. These conditions are sensed by inputs to the ECU from Start, TS1 and TS2, TC, TPS, and the MPS. The ECU adds additional pulses (during acceleration) and/or modifies the value of Tb for these conditions, resulting in the final injection pulse of Ti.

AIR FLOW SENSOR A mass airflow sensor is used to

determine the mass of air entering an electronically fuel-injected engine.

The air mass information is necessary for the ECU to calculate and deliver the correct fuel mass to the engine.

Air changes its density as it expands and contracts with temperature and pressure.

When a MAF is used in conjunction with an oxygen sensor, the engine's air/fuel ratio can be controlled very accurately.

The MAF sensor provides the open-loop predicted air flow information (the measured air flow) to the ECU, and the sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass.

Throttle position sensor A throttle position sensor (TPS) is

a sensor used to monitor the position of the throttle in an internal combustion engine.

The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve.

The sensor signal is used by the ECU as an input to its control system.

The ignition timing and fuel injection timing are altered depending upon the position of the throttle

Parking sensorsParking sensors are a technology that allows the driver of an automobile, truck, or commercial vehicle to be alerted to nearby objects in their path. Parking sensors are also known as backup sensors, parking sonar or just sonar depending on the automaker. While there are variations in the design and feaures of these systems, the basic design puts sensors in the vehicle's bumper or on brackets. These sensors send ultrasonic waves at 40,000 times per second that detect obstacles behind the vehicle. A controller installed inside the vehicle then receives the signal from the sensors and transmits it to a speaker that emits a tone, or to a combination speaker and display unit.

Oxygen sensor An oxygen sensor is an electronic device that

measures the proportion of oxygen (O2) in the gas or liquid being analyzed

The most common application is to measure the exhaust gas concentration of oxygen for internal combustion engines in automobiles and other vehicles.

If the air fuel ratio exiting a gas-combustion engine is rich or lean ,Closed-loop feedback-controlled fuel injection varies the fuel injector output according to real-time sensor data rather than operating with a predetermined (open-loop) fuel map.

In addition to improving overall engine operation, they reduce the amounts of both unburnt fuel and oxides of nitrogen from entering the atmosphere.

Manifold Pressure Sensor The manifold pressure sensor (MPS) is an

interesting and complex electromechanical device.

The MPS measures engine load by sensing manifold pressure, transforming the load signal into an electrical response that the ECU uses to determine the appropriate injector pulse duration.

An "open loop" system, meaning that the ECU has no feedback that the pulse duration used produced the correct mixture.

Without feedback, the ECU cannot compensate for mixture changes required by engine modification , engine wear, or fuel composition.

While MPS does an amazingly good job in spite of this limitation, corrections to the mixture may be required, and an adjustment and calibration.

Various types of sensor & their functions

MAP Sensor/BAP Sensor

Crankshaft or Camshaft Position SensorMonitors the rotation of the engine and tells the computer exactly when to trigger the fuel injectors or the ignition spark.

Crankshaft or Camshaft Position Sensor

MAP Sensor/BAP SensorReads changes in barometric (air) pressure. The ECM uses this information to adjust timing advance and air/fuel ratio.

Various types of sensor & their functions

Detonation Sensor/Knock SensorListens for engine "ping" so the ECM can retard the spark timing, and thereby reduce emissions and overheating, if the engine is knocking.

EGR Valve Position SensorDetects the opening of the EGR valve, so the ECM can make adjustments to optimize performance.

Various types of sensor & their functions

Control Module/IgniterRegulates and times the spark signal to the ignition coil, for correct ignition without misfiring.

Coolant Temperature Sensor/CTSMeasures the temperature in the cooling system, so the ECM can make adjustments based on the engine's operating temperature. Can also control the dashboard warning light.

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