Patent ID: 6183207
Filing Date: 2001-02-06
Classification: F02M,F04B

Abstract:
A pump comprising:a housing having an inlet port, an outlet port and a pair of pumping chambers;a pair of connected and coutra-acting pumping pistons that is located within the pair of pumping chambers such that an intake stroke of one pumping piston corresponds to a discharge stroke of the connected pumping piston, the pair of pistons arranged to pump a fluid from the inlet port to the outlet port;an inlet check valve coupled to each of the pair of pumping chambers that controls a flow of the fluid from the inlet port to the pumping chamber, wherein the inlet check valve provides fluid communication between the pumping chamber and the inlet port when in an open position; and,a control piston coupled to the inlet check valve in each of the pair of pump chambers, each of the two control pistons coupled to move and maintain the inlet check valve in an open position when supplied with a pressurized fluid, anda control valve arranged to selectively supply pressurized fluid to the two control pistons.