Patent ID: 8562315

Claim:
A fuel pump comprising: a housing having therein a suction passage through which fuel is drawn, and a pressurization chamber into which the fuel from the suction passage flows; a plunger held in the housing to be reciprocable, the plunger being configured to pressurize the fuel flowing into the pressurization chamber; a diaphragm device located in a suction chamber that is provided in the suction passage, wherein the diaphragm device includes a pair of first and second diaphragms that are arranged to define an inner space therebetween and air-tightly sealed at its entire peripheries, the first and second diaphragms are made of metal, and generally have the same shape and the same thickness, and the first and second diaphragms each have an inside surface portion, the inside surface portions are disposed to oppose each other and spaced apart from each other by the inner space; and a mass addition member attached to the inside surface portion of one of the first and second diaphragms, wherein the mass addition member is a flat, planar member, and the mass addition member is spaced from the inside surface portion of the other of the first and second diaphragms.