Positive displacement fluid pumps

Claim 2

A positive displacement pump assembly comprising a pump housing, a pump rotor, a cam ring secured to said pump housing including a cam surface surrounding said pump rotor, pumping elements carried by said rotor in camming engagement with said cam surface, a reservoir formed in part by said housing and surrounding said rotor, an end plate secured to said cam ring, said end plate, said cam ring and said housing being secured together in fixed axial disposition, a reservoir cover surrounding said housing and cooperating therewith to partly define said reservoir, a wall on said cover extending over said end plate and cooperating therewith to define a fluid inlet cavity, said cam ring and said rotor defining pumping chambers, said pumping elements moving through said pumping chambers upon rotation of said rotor, high-pressure outlet porting formed in said housing, a high-pressure chamber in said housing communicating with said high-pressure porting, a fluid delivery passage, valve means in said housing communicating with said high pressure chamber for dividing the flow directed through said high-pressure porting to said delivery passage and to said inlet cavity, and inlet porting in said end plate in fluid communication with said pumping chambers and said inlet cavity.

Claim 3

A positive displacement pump assembly comprising a pump housing, a pump rotor, a cam ring secured to said pump housing including a cam surface surrounding said pump rotor, pumping elements carried by said rotor in camming engagement with said cam surface, a reservoir formed in part by said housing and surrounding said rotor, an end plate secured to said cam ring, said end plate, said cam ring and said housing being secured together in fixed axial disposition, a reservoir cover surrounding said housing and cooperating therewith to partly define said reservoir, a wall on said cover extending over said end plate and cooperating therewith to define a fluid inlet cavity, said cam ring and said rotor defining pumping chambers, said pumping elements moving through said pumping chambers upon rotation of said rotor, high-pressure outlet porting formed in said housing, a high-pressure chamber in said housing communicating with said high-pressure porting, a fluid delivery passage, valve means in said housing communicating with said high-pressure chamber for dividing the flow directed through said high-pressure porting to said delivery passage and to said inlet cavity, inlet porting in said end plate in fluid communication with said pumping chambers and said inlet cavity, a crossover passage extending from said valve means to said inlet porting, means defined partly by said crossover passage for accelerating fluid toward said inlet porting, a passage extending from said reservoir to said crossover passage, said crossover passage being in fluid communication with said reservoir through said last named passage whereby fluid is drawn from said reservoir by the aspirator action developed by the acceleration of fluid in said bypass passage, the pressure in said inlet porting being supercharged by the velocity head of the accelerated fluid in said bypass passage.

Claim 4

A positive displacement pump assembly comprising a pump housing, a pump rotor, a cam ring secured to said pump housing including a cam surface surrounding said pump rotor, pumping elements carried by said rotor in camming engagement with said cam surface, a reservoir formed in part by said housing and surrounding said rotor, an end plate secured to said cam ring, said end plate, said cam ring and said housing being secured together in fixed axial disposition, a reservoir cover surrounding said housing and cooperating therewith to partly define said reservoir, a wall on said cover extending over said end plate and cooperating therewith to define a fluid inlet cavity, said cam ring and said rotor defining pumping chambers, said pumping elements moving through said pumping chambers upon rotation of said rotor, high-pressure outlet porting formed in said housing, a high-pressure chamber in said housing communicating with said high-pressure porting, a fluid delivery passage, valve means in said housing communicating with said high-pressure chamber for dividing the flow directed through said high-pressure porting to said delivery passage and to said inlet cavity, inlet porting in said end plate in fluid communication with said pumping chambers and said inlet cavity, a crossover passage extending from said valve means to said inlet porting, means defined partly by said crossover passage for accelerating fluid toward said inlet porting, a passage extending from said reservoir to said crossover passage, said crossover passage being in fluid communication with said reservoir through said last named passage whereby fluid is drawn from said reservoir by the aspirator action developed by the acceleration of fluid in said bypass passage, the pressure in said inlet porting being supercharged by the velocity head of the accelerated fluid in said bypass passage.

Claim 5

The combination set forth in claim 1 wherein said outlet porting includes blind ports formed in said plate in registry with high-pressure portion of said pumping chamber whereby the pressure in said outlet port is balanced by the pressure in the ports in said plate, said inlet porting having blind inlet pressure ports formed in said housing in registry with said inlet porting whereby the pressure forces due to the supercharged pressure in said inlet porting is balanced by a counteracting pressure force in said blind inlet pressure ports.

Claim 6

The combination set forth in claim 2 wherein said outlet porting includes blind ports formed in said plate in registry with high-pressure portion of said pumping chamber whereby the pressure in said outlet port is balanced by the pressure in the ports in said plate, said inlet porting having blind inlet pressure ports formed in said housing in registry with said inlet porting whereby the pressure forces due to the supercharged pressure in said inlet porting is balanced by a counteracting pressure force in said blind inlet pressure ports.

Claim 7

The combination set forth in claim 3 wherein said valve means includes a flow restricting orifice in said delivery passage, a valve chamber in said housing, a movable valve element in said valve chamber arranged in registry with said orifice, said valve element being moved in one direction to decrease the effective flow area of said orifice upon an increase in the pressure in said outlet ports.

Claim 8

The combination set forth in claim 4 wherein said valve means includes flow restricting orifice in said delivery passage, a valve chamber in said housing, a movable valve element in said valve chamber arranged in register with said orifice, said valve element being moved in one direction to decrease the effective flow area of said orifice upon an increase in the pressure in said outlet ports.