High pressure liquid pump

Claim 1

A fluid pump comprising a main housing portion, a second housing portion having a cavity with an open end, said second housing portion being secured to one face of said main housing portion, a cam ring in said second housing portion and a pump rotor in said cam ring, pumping elements carried by said rotor in sliding engagement with the adjacent internal walls of said cam ring, said rotor and said cam ring cooperating to define a pumping chamber, first and second port plates located between said cam ring and the adjacent face of said main housing portion, a third port plate adjacent the opposite side of said cam ring, an end plate engaging said third port plate, said first and second port plates having a high pressure port and a low pressure port, means for sealing the interior of said second housing portion to define two separate fluid pressure chambers, one of said pressure chambers being situated on one side of said end plate and being in fluid communication with said high pressure ports whereby pressure in said one chamber acts upon said end plate and said second port plate and urge said end plate, said port plate and said cam ring into axially stacked relationship, the second pressure chamber in said second housing portion being of lower pressure and communicating with the inlet port in said first and second port plates, said main housing portion having a low pressure recess and a high pressure recess in communication respectively with said low pressure port and said high pressure port, a fluid delivery passage extending from said pump, valve means in said first housing portion and defining in part said fluid delivery passage for establishing flow control and pressure relief including a pressure sensitive valve element and a valve chamber slidably receiving said valve element, one side of said valve element being subjected to the pressure in said outlet port, and a bypass passage registering with said valve element and connecting said valve chamber with the low pressure port, a velocity pressure port in said delivery passage, a crossover passage extending from said velocity pressure port to the other side of said valve element comprising a pair of openings in said second port plate in communication respectively with said velocity pressure port and said other valve element side, a groove in one face of said first port plate, said one face engaging said second port plate and defining therewith a pressure distribution path, a fluid reservoir comprising an open end cover surrounding said first and second housing portions and cooperating with said first and second housing portions to define a reservoir chamber, means for sealing the outermost margin of said cover on said first housing portion, and an internal passage structure in said first housing portion providing fluid communication between said reservoir chamber and said low pressure port.