Functional description
The EGR controller is opened or closed electrically by the DDE control unit. To ensure optimized control of the exhaust-gas recirculation rate, the exact position must be continuously detected. The position of the EGR controller is monitored by a noncontact hall effect sensor.
| Item | Explanation |
|---|---|
| 1 | EGR controller |
| 2 | five-pin plug connection |
| 3 | Exhaust-gas recirculation cooler |
| 4 | Bypass valve for exhaust-gas recirculation cooler |
The mean quantity adaptation serves to adapt the exhaust-gas recirculation more precisely to tolerance in the fuel injection rates. The air ratio measured by the oxygen sensor and the air mass measured by the hot film air mass meter are used to determine a mean fuel injection rate across all cylinders. This value is compared with the fuel injection rate specified by the DDE control unit. If there is a deviation, the air mass is adapted to the actual fuel injection rate by adjusting the EGR controller in such a way that the correct air ratio is set. The mean quantity adaptation is not a rapid control operation, rather an adaptive learning procedure. That means that the fuel injection rate error is learned in an adaptive characteristic map that is stored permanently in the DDE control unit.