Patent ID: 7806671
Filing Date: 2010-10-05
Classification: B60T,F04B

Abstract:
1. A piston pump comprising: a pump housing having a cylinder bore, a suction port, and a discharge port; a piston defining a pump chamber within the cylinder bore, the piston being axially reciprocated so as to increase and decrease a volume of the pump chamber; a suction valve provided at a suction side of the pump chamber, opening when the volume of the pump chamber increases, and closing when the volume decreases; and a discharge valve provided at a discharge side of the pump chamber, opening when the volume of the pump chamber decreases, and closing when the volume increases, wherein a cylindrical seat member is externally fitted in a fixed condition to an end portion of the piston located on a side of the piston toward the pump chamber; a valve port and a valve seat of the suction valve are formed at an end portion of the cylindrical seat member located on the side toward the pump chamber; a plurality of communicating grooves are formed on an outer circumferential portion of the piston located on the side of the piston toward the pump chamber, the communicating grooves extending axially; and a recess is formed at a center portion of an end face of the piston located on the side toward the pump chamber, the recess being coaxial with the piston and opening toward the valve port of the suction valve so that an inner circumference of the recess establishes communication among bottom portions of the communicating grooves at the end face of the piston located on the side toward the pump chamber.