P49.10-A050-79
Example illustration of exhaust gas flap controller for diesel engine |
1 | Exhaust flap controller |
P49.10-A062-79
Example illustration of exhaust gas flap controller for spark-ignition engine |
2 | Exhaust flap controller |
Overview
This document contains information on:
General
Function
General
For spark-ignition engines:
For large-displacement spark-ignition engines, cylinders are deactivated in certain load ranges to reduce consumption. This also affects the acoustics of the engine and the exhaust system. With the exhaust gas flap controller, the flow cross-section of the exhaust system can be changed. This achieves sound effects that make the engine sounds like it is normal operation.
For diesel engines:
If the pressure gradient in the low-pressure system is not enough to regulate the requested exhaust gas recirculation mass flows, an exhaust gas flap controller is used to generate back pressure. This enables a defined pressure buildup and thus controlled exhaust gas recirculation for reducing pollutants.
Function
The powertrain control unit actuates the exhaust gas flap controller depending on the request from the combustion engine control unit. The combustion engine control unit provides the powertrain control unit with a specified value from 0 to 100 % that corresponds to an adjustment angle between 0 and 90°.
The position control in the powertrain control unit controls the exhaust flap to the requested specified value.
The Hall sensor in the exhaust gas flap controller reports back the actual position to the powertrain control unit.
The energized actuator motor at the exhaust flap controller closes the exhaust flap. In a deenergized state, the exhaust flap is opened by a return spring.
When the ignition is ON (circuit 15), the exhaust gas flap performs a self-test. The self-test checks the function of the return spring and for any possible jamming.
For all 10 driving cycles, the exhaust flap learns the internal flap end stops in the run-on.