Patent ID: 7766631
Filing Date: 2010-08-03
Classification: F04B,Y10T

Abstract:
1. A piston pump including: a cylindrical cylinder having a top portion; a piston being formed in a cup shape with an outer peripheral surface and a cylindrical hollow portion inside, the piston reciprocating inside the cylinder as the outer peripheral surface slides directly on an inner wall of the cylinder; a suction port through which gas is sucked into a pump chamber defined by a side of wall of the top portion of the cylinder, a side wall of the cylinder and a top face of the piston; an exhaust port through which the gas is discharged from the pump chamber; a recess portion disposed continuously around an inner wall of the cylindrical hollow portion of the piston in a circumferential direction of the piston; a coupling ring having a projecting portion that fits on the recess portion such that the coupling ring engages with the piston wherein the cylindrical hollow portion communicates with a center portion of the coupling ring; and a connecting ring connected to the coupling ring that transmits mechanical force from the connecting ring to the piston; wherein the piston pump sucks the gas from the suction port and discharges the gas through the exhaust port as a volume of the pump chamber is changed by reciprocating motion of the piston; wherein the suction port is arranged at the top portion of the cylinder with a suction valve, which opens when the volume of the pump chamber is increased; and the exhaust port is arranged at the piston with an exhaust valve, which is umbrella-shaped and is arranged outside the pump chamber and opens when the volume of the pump chamber is decreased, the piston having a hole at a center thereof in order to fix the exhaust valve; and wherein an inner diameter of the cylinder is adaptedly formed not exceeding 20 mm.