Torque Coordination, Basic Function - GF07.10-P-1060A

Engine All (CAR) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Coordinate Engine torque. 
  • Request Engine torque. 
  • Adjust Engine torque. 
  • Use torque reserve (spark-ignition Engine). 

General 

The torque coordination coordinates and prioritizes the torque requests of all vehicle systems made to the Engine or, for a hybrid vehicle, made to the hybrid system.

Function requirements 

• Engine management ON (circuit 87M)
• Engine in operation

Function 

Coordinate Engine torque 

Various vehicle systems can request Engine torque, such as the accelerator pedal or speed control. These torque requests can contradict each other.

To coordinate the various torque requests, the torque coordination intervenes in the Engine management system.

For the decision as to which torque request will be permitted, the torque coordination uses, among other things, the following information:

• Driveability:

  The torque coordination judges whether good driveability is guaranteed. For example, torque requests that are uncomfortable to the driver are prevented.

• Specified priority:

  For various systems, different priorities are specified for torque requests. For example, driving safety systems have a higher priority than driver assistance systems.

For a hybrid vehicle, the torque coordination uses information from the electric drive, from the high-voltage battery, and from the automatic transmission in addition.

Request Engine torque 

The following vehicle systems can make an Engine torque request, among other things:

• The driver, via the accelerator pedal sensor
• The brake and traction control system
• Speed control and limitation
• Transmission control
• Distance control
• RPM limitation
• Maximum vehicle speed limit
• Maximum torque limitation

Adjust Engine torque 

The combustion Engine control unit adapts the Engine torque via the following parameters:

• Extending or shortening the injection duration of fuel injectors.
• Advancing or retarding the ignition angle.
• A combination of adjustment of the injection duration and adjustment of the ignition angles.
• Hybrid vehicle: Drive torque of the electric machine.

Usage of torque reserve (spark-ignition Engine) 

To increase the Engine torque quickly and comfortably for the driver, the torque reserve must be used.

A torque reserve is achieved by extending the injection period, while simultaneously adjusting the ignition angles to "retarded". This will enrich the fuel-air mixture, while at the same time preventing a premature torque increase due to the retarding of the timing. Setting the ignition angles to "early" results in the Engine torque being increased.