Engine control unit

A modern engine control unit ( also engine control unit or Engine Control Unit) is a specially developed computer (control unit ), which takes over the control, regulation and monitoring of engine functions.

Basics

In more modern internal combustion engines with electronic throttle valve and the air mass sensor measures the mass of air, the mixture ratio ( air to fuel ) and catalytic emission control and exhaust gas recirculation and with a variable valve timing the opening and closing ( crankshafts ) angle of the intake and exhaust valves to the current requirements adjusted accordingly. For motors with suitable charging and the charge pressure can be regulated.

Construction

Strictly speaking, these are usually not open-loop control, but a closed-loop control, because the measured with a sensor actual state is compared with a calculated target state (feedback) and is then minimized via an actuator, the deviation in the closed loop. It refers to the software in the engine control as an electronic engine management.

Modern engine control systems are 32- bit microcontrollers, such as Infineon TriCore, equipped to enough to handle the required real-time computing operations quickly and accurately. But can also be advantageous, motor control supplement with FPGAs, since these digital functions run faster. As far as the numbers allow it, can also be found in ASICs integrated microcontroller.

Characteristic of a engine control computer is the integrated interface for analog and digital input signals from sensors and output signals for the actuators as well as the CAN bus for communication with other control units in the vehicle. For the on-board diagnostics, there is a separate, prescribed and standardized interface in order to read with appropriate equipment, the fault memory can.

Typical input signals include the accelerator position (driver demand), the engine speed, the throttle angle, the air mass flow, various temperatures and pressures as well as the oxygen sensor and the knock sensor signal.

Typical output signals activate the ignition and injectors as well as in modern engines, including the throttle actuator, the exhaust gas recirculation valve, the turbocharger and variable valve timing.

Overview of functions

The engine control unit is one of the main control unit of a motor vehicle. It performs the necessary calculations for the operation of the engine in the vehicle, such as:

  • Actuation and control of the throttle valve (also called E-Gas )
  • Lambda control
  • On- Board Diagnostics ( OBD) for emission- affecting components (eg injectors, oxygen sensors, catalyst)
  • Control of charging
  • Controlling the idle speed (idle)
  • ECU self-diagnosis
  • Control of the base engine features fuel injection and ignition
  • V- Max ( electronically limited top speed )

An engine electronic control unit consists of, in principle:

  • Microcontroller
  • RAM, ROM and flash memory
  • Analog and digital I / O interfaces

Engine control units may have more than 200 connections.

The engine control unit has over other control devices, the special feature that it cyclically running programs to run not only at fixed time intervals, but in parallel and synchronized with engine speed, for example, to calculate the ignition timing.

For the regulation and control tasks processes the sensor data, the engine control unit including:

  • Intake air mass flow
  • Ambient barometric air pressure
  • Knock sensor
  • Fuel pressure signal
  • Signal of the oxygen sensor ( s)
  • Temperature of the aspirated air
  • Temperature of the engine coolant
  • The temperature and pressure of the engine oil
  • Winkel-/Drehlzahlgeber of the crankshaft and camshaft (s)
  • Angle transmitter throttle

And user signals such as:

  • Brake signal
  • Driving speed control system ( cruise control )
  • Accelerator pedal angle
  • Clutch pedal switch

And can with the input signals under consideration of stored maps calculated output signals or specify the appropriate actuators nominal sizes:

  • Exhaust gas recirculation valve
  • Throttle position
  • Injection timing and injection quantity
  • Generator excitation
  • Catalyst heating
  • Air conditioner compressor clutch
  • Compressor control
  • Fuel pump
  • Charge movement flaps
  • Fan control
  • Camshaft adjustment
  • The tank venting valve
  • Turbocharger wastegate control
  • Valve
  • Ignition timing and ignition

The engine control unit is often linked via the CAN bus with other control units, such as transmission control, ABS, ESP, instrument cluster and air conditioning.

The engine control unit is usually in a protected place at the bulkhead or often fitted to the interior ( under the dashboard ). An engine control unit usually heard (after replacement engine and gearbox ) to the most expensive parts of a car, this is mainly because that the control unit under difficult operating conditions, such as a very wide temperature range, vibrations from the engine and vibrations caused by road conditions as well as over- and undervoltage, to function properly. There can be often supplied or repaired in the interchange.

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