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 detecting the compression stroke at 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).
The signals of the camshaft position sensor (B601) are then used exclusively to determine the engine speed or the compression stroke of cylinder 1 if the crankshaft position sensor (B600) fails.
The reason for this is that the crankshaft position sensor (B600) provides more precise values for the crankshaft position than the camshaft position sensor (B601). The start of actuation of the cylinder 1 fuel injector (Y608), cylinder 2 fuel injector (Y609), cylinder 3 fuel injector (Y610), cylinder 4 fuel injector (Y611), cylinder 5 fuel injector (Y612), and cylinder 6 fuel injector (Y613) can thus be determined more exactly.
Function
The camshaft sprocket (2) on the intake camshaft has 12 grooves (3) that are each distributed with a spacing of 30° from each other over the entire circumference of the camshaft sprocket (2) as well as an additional groove (4) before the 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 control unit (MCM) (A4) uses the additional groove (4) to check when cylinder 1 is in its compression stroke.
As the engine management control unit (MCM) (A4) uses the crankshaft position sensor (B600) to determine the position of the crankshaft 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 the signals of the crankshaft position sensor (B600) are then solely sufficient to determine the compression stroke of cylinder 1 and thus the start of actuation of the cylinder 1 to 6 fuel injectors (Y608 to Y613).