Shown on engine 471.9 |
1 | Flywheel |
2 | Camshaft sprocket |
3 | Nut (to detect the crankshaft angle upon failure of the crankshaft position sensor) |
4 | Additional groove (for recognizing the compression stroke on cylinder 1) |
A4 | Engine management control unit (MCM) |
B600 | Crankshaft position sensor |
B601 | Camshaft position sensor |
W07.16-1064-82
General
Detection of the compression stroke at cylinder 1 takes place as soon as the engine has started. Because the position of the crankshaft alone is not enough to do this, the engine management (MCM) control unit (A4) also uses the signals from the camshaft position sensor (B601).
If the compression cycle at cylinder 1 is, however, just known the one time then all further compression cycles are just calculated based on signals from the crankshaft position sensor (B600).
Signals from the camshaft position sensor (B601) are exclusively used to determine the rotational speed or the compression cycle at cylinder 1 if the crankshaft position sensor (B600) fails.
The reason for this is that the crankshaft position sensor (B600) delivers more precise values on the crankshaft position than the camshaft position sensor (B601). Therefore, the actuation begin of the fuel injector for cylinder 1 (Y608), fuel injector for cylinder 2 (Y609), fuel injector for cylinder 3 (Y610), fuel injector for cylinder 4 (Y611), fuel injector for cylinder 5 (Y612), and fuel injector for cylinder 6 (Y613) can be determined more exactly.
Function
The camshaft sprocket located on the intake camshaft (2) has 12 grooves (3), which are each distributed at in interval of 30° over the total circumference of the camshaft sprocket (2), and an additional groove (4) before top dead center (TDC) of cylinder 1.
As soon as the intake camshaft turns, the grooves in the camshaft position sensor (B601) generate changes in the magnetic field which are converted by an electronic analysis system into shift signals and passed on to the engine management (MCM) control unit (A4).
If the engine is started, the engine management (MCM) control unit (A4) checks when cylinder 1 is located in the compression stroke using the additional groove (4).
Because, the engine management (MCM) control unit (A4) determines the position of the crankshaft via the crankshaft position sensor (B600) at the same time, it can compare the position of the additional groove (4) to the position of the gap on the flywheel so that signals of the crankshaft position sensor (B600) are then sufficient on their own to determine the compression stroke of cylinder 1 and thus determine the actuation begin of the fuel injectors for cylinder 1 to 6 (Y608 to Y613).