Determination of the engine speed and crankshaft angle, function

W07.15-1329-78

1 Flywheel

2 Grooves - to detect the engine speed

A6 MR/PLD control unit

B15 Crankshaft angle position sensor

3 An additional groove - to detect the crankshaft angle

The engine speed is taken from the flywheel (1) on the crankshaft. To this end the circumference of the flywheel (1) 36 has uniformly distributed grooves located around it (2), i.e. each at a distance of 10° apart.

Each of these grooves (2) triggers a pulse in the crankshaft angle position sensor (B15). An additional groove (3) is located at a 65° crankshaft angle upstream of the top dead center (TDC) of the 1st. cylinder. It delivers a characteristic additional impulse. This means that not only the engine speed but also the angular position of the crankshaft can be determined at any time.

The MR/PLD control unit (A6) starts an internal counter (trigger) once it receives a pulse from the crankshaft angle position sensor (B15). Calculations yield the crankshaft position and the engine speed.

Calculation of the intermediate values makes it possible for the engine control (MR) to exactly determine the start of injection and the period of injection to a fraction of a degree.