Patent ID: 9644585
Date: 2017-05-09
CPC Classifications: F02M

Claim:
1. A fuel pump having a low pressure fuel inlet and a single piston pumping chamber for supplying a metered quantity of high pressure fuel through a pump outlet and high pressure fuel line to an inlet side of a common rail, comprising: a control valve hydraulically connected to the pumping chamber for metering the quantity of fuel pumped through the pump outlet; a primary pressure relief valve having an inlet side in hydraulic communication with the inlet side of the common rail and an outlet side in fluid communication with the pumping chamber; and an auxiliary pressure relief valve having an inlet side in direct hydraulic communication with one of the pumping chamber or inlet side of the common rail and an outlet side in direct fluid communication with a fuel passage at the low pressure of the pump inlet; wherein said fuel passage at the low pressure of the pump inlet is an infeed fuel passage, said control valve meters a flow of low pressure fuel through said infeed fuel passage from said fuel inlet to said pumping chamber during a charging stroke of the pump, and the outlet side of the auxiliary pressure relief valve is in direct hydraulic communication with said infeed fuel passage upstream of the control valve.