To provide a plunger pump preventing the fuel leakage by preventing the fuel pressure in a pump body from abnormally raising, while attaining the lightweight and the cost reduction of the pump body.
A plug 64 closing a cylinder storage hole 16 and provided with a communication channel 72 communicated with a fuel channel outlet 42 of a cylinder assembly 24 and a spring 80 energizing the plug in a prescribed direction, is set movable to the cylinder assembly and an O ring 74 is provided on the opposed face of the assembly. Where the fuel pressure in the fuel channel 32 is a prescribed value or less, the O ring touches the cylinder assembly by the spring so as to prevent the fuel leakage from the opposed face and, where the fuel pressure in the channel raises to the prescribed pressure or more, the fuel pressure resists against the spring so that the O ring releases the leakage prevention in the opposed face and releases a part of the fuel to the outside to reduce the fuel pressure.
TAKEHANA NORIO
SHICHI AKIRA
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