Patent ID: 7874814

Claim:
A piston pump comprising: a housing; an electric motor connected to the housing, wherein the electric motor is installed in a vehicle in which a rotation shaft of the electric motor is substantially horizontal; a cam that rotates together with the electric motor; and a piston that reciprocates in accordance with the rotation of the cam so that fluid is drawn and discharged, wherein the housing includes a cam chamber in which the cam is housed, wherein the cam chamber is shaped like a circular cylindrical hollow and extends horizontally and parallel to the axis of the rotation shaft, the cam chamber has first and second ends, which are opposite to one another, and the first end of the cam chamber, which is relatively closer than the second end of the cam chamber to the electric motor, is open, and the second end of the cam chamber is closed; a piston bore, in which the piston is located, wherein one end of the piston bore is open to a side wall surface of the cam chamber that surrounds an axis of the rotation shaft; and a fluid reservoir that is formed by a depression in a bottom side of the side wall surface of the cam chamber, wherein the fluid reservoir is configured to retain fluid that has leaked into the cam chamber from the piston bore, and an edge is formed between the bottom side of the side wall surface of the cam chamber and the fluid reservoir, and a section of the edge that is located closer to the first end of the cam chamber than the piston bore extends downward beneath the piston bore toward the second end of the cam chamber.