OVERFLOW VALVE FOR A FUEL INJECTION SYSTEM AND FUEL INJECTION SYSTEM COMPRISING AN OVERFLOW VALVE

摘要

The invention relates to an overflow valve for a fuel injection system, in particular a common rail injection system, wherein the fuel injection system comprises a pre-supply pump (1) and a high-pressure pump (3), to which fuel from a fuel tank (2) is delivered by means of the pre-supply pump. The fuel injection system further comprises a metering unit (4) for regulating the amount of fuel to be delivered to at least one pump element (6) of the high-pressure pump (3) via an inlet (5). The overflow valve (7) is arranged between the pre-supply pump (1) and the metering unit (4) and comprises an axially displaceable valve piston (8), the axial displacement of which allows at least one discharge opening (9) to be opened or closed. According to the invention, an axially extending flow channel (10) having a cross-section constriction (11) is formed inside the valve piston (8), wherein in the region of the cross-section constriction (11) a substantially radial borehole (12) leads into the flow channel (10), via which borehole the flow channel (10) can be hydraulically connected to the inlet (5) downstream of the metering unit (4).