Patent ID: 6183217
Filing Date: 2001-02-06
Classification: F01L

Abstract:
A pump, comprising:a valve body having an internal bore;a piston coupled to the valve body having an upper surface and a lower surface, the piston positioned within a piston housing to define an upper piston chamber and a lower piston chamber;a fluid inlet port in the valve body for communicating pressurized fluid to the valve body;a first pressurized fluid conduit for communicating pressurized fluid from the valve body to the lower piston chamber to act on the lower surface of the piston;a valve member slidable within the internal bore being selectively shiftable between first and second positions, the valve member having first and second pressure receiving surfaces selectively exposed to pressurized fluid from the fluid inlet port, the valve member in the first position defining a first pressurized chamber between the first pressure receiving surface of the valve member and the inner surface of the valve body and communicating pressurized fluid from the first pressurized chamber through the first pressurized fluid conduit to the lower piston chamber to act on the lower surface of the piston to move the piston from a first position to a second position;a fluid exhaust conduit for communicating fluid from the valve body to a low pressure source;venting means responsive to the piston in the second position for communicating fluid acting on the second pressure receiving surface of the valve member through the fluid exhaust conduit to the low pressure source, the pressurized fluid in the first pressurized chamber acting on the first pressure receiving surface of the valve member in response to the depressurization of the fluid acting on the second pressure receiving surface to move the valve member from the first position to the second position;a second pressurized fluid conduit for communicating pressurized fluid from the valve body to the upper piston chamber to act on the upper surface of the piston;the valve member in the second position defining a second pressurized chamber between the second pressure receiving surface of the valve member and a lower cap surface of a top cap of the valve body and communicating pressurized fluid to the upper piston chamber to act on the upper surface of the piston to move the piston from the second position to the first position;the venting means responsive to the piston in the first position for communicating fluid acting on a lower end surface of the valve member through the fluid exhaust conduit to the low pressure source, the pressurized fluid in the second pressurized chamber acting on the second pressure receiving surface of the valve member to move the valve member from its second position to its first position.