Overview
This document contains information on:
General
Function requirements
Function
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:
Drivability
The torque coordination judges whether good drivability 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 the fuel injectors
Advanced 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
Spark-ignition engine: Use torque reserve
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.
Function schematics | |||
Function schematic for torque coordination | Engine 608 in model 118, 177, 247 | ||
Engine 282 in model 118, 177, 247 | |||
Engine 256 in model 223 | |||
Engine 176, 177 in model 167 | |||
Engine 254, 256, 264 in model 213 as of model year 2021Engine 256 in model 167Engine 256 in model 238, 257 as of model year 2021 | |||
Engine 139 in model 118, 177 | |||
Engine 176, 177 in model 223 | |||
Engine 279 in model 223 |