Patent ID: 8226379

Claim:
A hydraulic pump comprising: a housing having a compression chamber and a fluid passage; a seat portion provided midway through the fluid passage; a valve element located between the compression chamber and the fluid passage to control communication therebetween through a communication channel by being lifted from and seated to the seat portion, the valve element being substantially a plate-shaped member; a solenoid actuator provided upstream of the valve element with respect to fluid flow for manipulating the valve element by lifting the valve element from the seat portion; and a stopper configured to make contact with an end of the valve element to regulate movement of the valve element in a direction opposite to the seat portion, wherein the communication channel is defined between the housing and an outer circumferential periphery of the stopper, the stopper is a closed-end cylindrical member having a bottom portion being closed to fluid, a cylindrical portion extending from an outer circumferential periphery of the bottom portion, and an opening end defined by the cylindrical portion, the bottom portion and the opening end being located at opposite axial ends of the cylindrical portion, the bottom portion being located farther away from the valve element than the cylindrical portion, and the opening end is configured to make contact with the end of the valve element.