Determination of the engine speed and crankshaft angle - function

W07.15-1245-78

1 Flywheel

2 Grooves for detecting the engine speed

A6 MR/PLN control unit

B15 Crankshaft angle position sensor

3 Additional groove for detecting the crankshaft angle

The engine speed is taken from the flywheel (1) on the crankshaft. There are 36 evenly spaced grooves on the circumference of the flywheel (1) for this purpose which are each spaced at a 10° angular spacing from each other.

Every one of these grooves (2) triggers a pulse in the crankshaft angle position sensor (B15). One additional groove (3) is located at a 65° crankshaft angle before the top dead center (TDC) of the 1st cylinder. It delivers a characteristic additional pulse. This allows not only the rotational speed but also, at any time, the angular position of the crankshaft to be determined.

As soon as the MR/PLN control unit (A6) receives a pulse from the crankshaft angle position sensor (B15), it starts an internal counter (trigger). Calculations allow determination of the crankshaft position and engine speed.

Calculation of intermediate values allows the engine control (MR) to exactly establish the start of injection and injection duration to within a fraction of a degree.