Location
The quantity control valve (Y642) is located on the fuel system high pressure pump.
Shown on engine 471.9 |
Y642 | Quantity control valve |
W07.16-1068-11
Task
The quantity control valve (Y642) has the following tasks to fulfill:
Regulation of the fuel inflow to the pump elements of the fuel system high pressure pump
Regulation of the rail pressure
Discontinuity of fuel supply to pump elements of the fuel system high pressure pump for "Engine stop"
Structure
1 | Fuel high pressure pump housing |
2 | Coil |
3 | Float needle |
4 | Valve spring |
Y642 | Quantity control valve |
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Function
The engine management (MCM) control unit (A4) actuates the coil (2) of the quantity control valve (Y642) using a pulse width modulated signal. The magnetic field of the coil (2) produced in this way influences the position of the float needle (3) and thus the flow area in the quantity control valve (Y642) and flow rate of the fuel.
At "Engine stop" the float needle (3) is pushed back by the valve spring (4) and the fuel flow rate is interrupted.