Inlet Valve Arrangement for a Fuel Pump

摘要

An inlet valve arrangement for a pump head of a fuel pump for use in a common rail fuel injection system comprises an inlet valve member (10) moveable between open and closed positions to control the flow from a source of low-pressure fuel to a pumping chamber (6) of the fuel pump. The inlet valve member (10) is arranged to open in response to the pressure difference between the fluid pressure of fuel on an inlet side of the inlet valve member (10) and the fluid pressure in the pumping chamber (6) exceeding a threshold value. The inlet valve arrangement (9) comprises means for selectively applying a closing force on the inlet valve member (10) to bias it toward the closed position, such that, in use, the application of the closing force by said means acts to increase the threshold value of the pressure difference at which the inlet valve member (10) opens.