Pumps with servo-type actuation for cheek plate unloading

Claim 3

The method of claim 1 and further characterized by actuating the servo valve by the pressure drop across an orifice in the outlet line.

Claim 4

The method of claim 1 and further characterized by actuating the servo valve by the pressure drop across an orifice in the pump return line.

Claim 5

In a pump having a non-rotatable axially movable pressure-loaded cheek plate sealing the respective inlet and outlet portions in a pump containing rotary fluid displacement means, the improvement of means forming a static cavity behind said cheek plate, means forming a venting passage from the static cavity to a zone at a reduced pressure, pumping circuit means forming a pump output and a pump return for placing the pump in a pumping circuit, means forming a flow control orifice in said pumping circuit means, a servo valve for controlling said venting passage and thus venting the pressure in said static cavitY acting on the cheek plate, whereby the cheek plate will act as a slave and the servo valve will act as the master to establish a servo ratio effect, and means for referencing the servo valve to the pressure drop across said orifice, whereupon unloading the cheek plate the outlet portions of the pump will be bypassed directly to the inlet portions thereof to modulate the pump flow output.

Claim 6

In a pump having a non-rotatable axially movable pressure-loaded cheek plate sealing the respective inlet and outlet portions in a pump containing rotary fluid displacement means, the improvement of means forming a static cavity behind said cheek plate, means forming a venting passage from the static cavity to a zone at a reduced pressure, pumping circuit means forming a pump output and a pump return for placing the pump in a pumping circuit, means forming a flow control orifice in said pumping circuit means, a servo valve for controlling said venting passage and thus venting the pressure in said static cavitY acting on the cheek plate, whereby the cheek plate will act as a slave and the servo valve will act as the master to establish a servo ratio effect, and means for referencing the servo valve to the pressure drop across said orifice, whereupon unloading the cheek plate the outlet portions of the pump will be bypassed directly to the inlet portions thereof to modulate the pump flow output.

Claim 7

In a pump as defined in claim 4, said means forming an orifice forming said orifice in the return line of the pump and through which spent fluid is directed on the return line side of the pump.

Claim 8

In a pump as defined in claim 4, said means forming an orifice forming said orifice in the outlet line of the pump through which fluid discharged by the pump is directed before proceeding to a motoring means.

Claim 9

In a fluid pump as defined in claim 4, said servo valve comprising a spool valve having a tapered spool movable in a bore having lands and recesses, spring means initially loading said spool in one direction, said spool controlling the venting passage by gradually opening the passage due to the tapered configuration, thereby to produce an axial movement of the cheek plate but through a significantly lesser distance than the corresponding movement of the spool to maintain a flow level corresponding to a servo ratio effect in the flow regulation of the pump.

Claim 10

In a pump as defined in claim 4 and further characterized by means forming a metering passage from a source of pump generated pressure to said static cavity, and means forming a metering orifice for said metering passage.

Claim 11

In combination, a pump having housing means forming a pumping chamber having inlet and outlet portions, rotary fluid displacement means in said pumping chamber for moving the fluid at increased pressure from the inlet to the outlet portions, a cheek plate adjacent said pumping chamber having a sealing face for sealing the inlet and outlet portions during operation of the pump, means including said housing forming a static pressure control chamber behind said cheek plate and having an orificed metering passage to load said cheek plate with fluid at pump-generated pressure, means including said housing forming a pumping circuit including an outlet line and a return line for said pump receiving spent fluid returned to the pump, means forming an orifice in said pumping circuit, and a servo valve controlling a venting passage in said housing venting said pressure control chamber to a zone at lower pressure and having actuating means responsive to the pressure drop across said orifice, thereby valving the cheek plate in servo ratio proportion with the servo valve and directly by-passing the outlet portions of the pump to the inlet portions adjacent the sealing face of the cheek plate to modulate pump flow output.

Claim 12

In combination, a pump having housing means forming a pumping chamber having inlet and outlet portions, rotary fluid displacement means in said pumping chamber for moving the fluid at increased pressure from the inlet to the outlet portions, a cheek plate adjacent said pumping chamber having a sealing face for sealing the inlet and outlet portions during operation of the pump, means including said housing forming a static pressure control chamber behind said cheek plate and having an orificed metering passage to load said cheek plate with fluid at pump-generated pressure, means including said housing forming a pumping circuit including an outlet line and a return line for said pump receiving spent fluid returned to the pump, means forming an orifice in said pumping circuit, and a servo valve controlling a venting passage in said housing venting said pressure control chamber to a zone at lower pressure and having actuating means responsive to the pressure drop across said orifice, thereby valving the cheek plate in servo ratio proportion with the servo valve and directly by-passing the outlet portions of the pump to the inlet portions adjacent the sealing face of the cheek plate to modulate pump flow output.

Claim 13

A pump as defined in claim 9 wherein said orifice is formed in said return line and through which spent fluid is directed on the return line side of the pump.

Claim 14

A pump as defined in claim 9 wherein said orifice is formed in the outlet line of the pump and through which fluid discharged by the pump is directed before proceeding to a point of utilization.

Claim 15

The invention of claim 9 and further characterized by a hollow dowel pin extending through said cheek plate and into said housing means and forming a passage extending therethrough communicating at one end with said pressure control chamber, said servo valve controlling said passage at the other end of said passage in said dowel pin for selectively venting the pressure control chamber to a zone of reduced pressure, whereupon unloading of the cheek plate will by-pass the outlet portion to the inlet portions directly across the sealing face of the cheek plate.

Claim 16

In a pump having an axial row of parts including a cam ring forming a pumping chamber and an end plate formed with a sealing face adjacent the cam ring and means forming a pressure control chAmber behind the end plate, the improvement of hollow dowel pin means extending through the axial row of parts and having formed therein a venting passage communicating at one end with the pressure control chamber, orifice means for sensing a pressure gradient in the pump, and a servo valve in the pump responsive to changes in the pressure gradient controlling the other end of the venting passage to a zone of reduced pressure, thereby to selectively unload the end plate for by-passing the outlet portions of the pump directly to the inlet portions of the pump adjacent the sealing face.

Claim 17

In a pump having an axial row of parts including a cam ring forming a pumping chamber and an end plate formed with a sealing face adjacent the cam ring and means forming a pressure control chAmber behind the end plate, the improvement of hollow dowel pin means extending through the axial row of parts and having formed therein a venting passage communicating at one end with the pressure control chamber, orifice means for sensing a pressure gradient in the pump, and a servo valve in the pump responsive to changes in the pressure gradient controlling the other end of the venting passage to a zone of reduced pressure, thereby to selectively unload the end plate for by-passing the outlet portions of the pump directly to the inlet portions of the pump adjacent the sealing face.

Claim 18

In a pump having a return line, a valve in said return line having a tapered spool movable in a valve bore having lands and recesses, spring means initially loading said spool in one direction, means forming an orifice in said return line through which fluid in the return line is directed, said spool being movable as a function of the pressure drop across said orifice, and by-pass means comprising a pressure-loaded end plate having a sealing face forming one wall of a pumping chamber and having a motive surface loaded by fluid at pump-generated pressure, a venting passage for venting the pressure acting on said motive surface, said valve controlling said venting passage by gradually opening the passage due to the tapered surface, thereby to trigger a movement of the end plate to directly by-pass the outlet portions of the pump to the inlet portions thereof, said valve moving a significantly greater distance than said end plate to maintain a flow level, thereby to provide a servo ratio effect in the flow control regulation of said pump.

Claim 19

In a pump having a return line, a valve in said return line having a tapered spool movable in a valve bore having lands and recesses, spring means initially loading said spool in one direction, means forming an orifice in said return line through which fluid in the return line is directed, said spool being movable as a function of the pressure drop across said orifice, and by-pass means comprising a pressure-loaded end plate having a sealing face forming one wall of a pumping chamber and having a motive surface loaded by fluid at pump-generated pressure, a venting passage for venting the pressure acting on said motive surface, said valve controlling said venting passage by gradually opening the passage due to the tapered surface, thereby to trigger a movement of the end plate to directly by-pass the outlet portions of the pump to the inlet portions thereof, said valve moving a significantly greater distance than said end plate to maintain a flow level, thereby to provide a servo ratio effect in the flow control regulation of said pump.

Claim 20

In a pump, a cam ring forming a pumping chamber for a fluid displacement means operable in said pumping chamber, a cheek plate for sealing against said cam ring, thereby to seal the pumping chamber, means including said cheek plate forming a static chamber receiving fluid at pump-generated pressure and whereby said cheek plate is pressure-loaded against said cam ring, and venting means for said chamber including a venting passage and a servo valve in control of said venting passage and forming the master valve of a control system wherein the cheek plate forms a slave valve, orifice means externally of said static chamber in the pumping circuit of the pump for developing a pressure gradient independently of the pressure in said static chamber upon buildup of pressure in the pump outlet caused by normal parasitic losses in a downstream hydraulic flow circuit, and means for actuating said servo valve as a function of the pressure drop across said orifice means, thereby to vent said chamber to unload the cheek plate and modulate pump flow output.

Claim 21

In a pump, a cam ring forming a pumping chamber for a fluid displacement means operable in said pumping chamber, a cheek plate for sealing against said cam ring, thereby to seal the pumping chamber, means including said cheek plate forming a static chamber receiving fluid at pump-generated pressure and whereby said cheek plate is pressure-loaded against said cam ring, and venting means for said chamber including a venting passage and a servo valve in control of said venting passage and forming the master valve of a control system wherein the cheek plate forms a slave valve, orifice means externally of said static chamber in the pumping circuit of the pump for developing a pressure gradient independently of the pressure in said static chamber upon buildup of pressure in the pump outlet caused by normal parasitic losses in a downstream hydraulic flow circuit, and means for actuating said servo valve as a function of the pressure drop across said orifice means, thereby to vent said chamber to unload the cheek plate and modulate pump flow output.

Claim 22

In a pump as defined in claim 15, said servo valve being actuated by pressure drop across an orifice formed in the outlet line of the pump and through which fluid at pump-generated pressure is directed.

Claim 23

In a pump as defined in claim 15, said servo valve being actuated by pressure drop across an orifice formed in the return line of the pump and through which spent fluid is directed on the return line side of the pump.

Claim 24

In a pump as defined in claim 15, housing means and reservoir means successively outwardly adjacent said cam ring, and openings in said housing means forming conduits for flow from the reservoir and being disposed so that the fast by-pass over the cam ring from the plate lift inducts out from the reservoir to accomplish super-charge.

Claim 27

In a pump having a pressure-loaded cheek plate sealing the respective inlet and outlet portions of a pumping chamber containing fluid displacement means, the improvement of a servo valve for venting the pressure acting on the cheek plate, means forming an orifice in the return line of the pump and through which spent fluid is directed on the return line side of the pump, and means for referencing the servo valve to the pressure drop across said orifice, whereby upon loading the cheek plate the outlet portions of the pump will be by-passed directly to the inlet portions thereof.

Claim 28

In a pump having a pressure-loaded cheek plate sealing the respective inlet and outlet portions of a pumping chamber containing fluid displacement means, the improvement of a servo valve for venting the pressure acting on the cheek plate, means forming an orifice in the return line of the pump and through which spent fluid is directed on the return line side of the pump, and means for referencing the servo valve to the pressure drop across said orifice, whereby upon loading the cheek plate the outlet portions of the pump will be by-passed directly to the inlet portions thereof.

Claim 29

In combination, a pump having housing means forming a pumping chamber having inlet and outlet portions, rotary fluid displacement means in said pumping chamber for moving the fluid at increased pressure from the inlet to the outlet portions, a cheek plate adjacent said pumping chamber having a sealing face for sealing the inlet and outlet portions during operation of the pump, means including said housing forming a pressure control chamber behind said cheek plate to load said cheek plate with fluid at pump-generated pressure, means including said housing forming a return line for said pump receiving spent fluid returned to the pump, means forming an orifice in said return line and through which spent fluid is directed on the return line side of the pump, and a servo valve controlling a passage in said housing venting said pressure control chamber to a zone at lower pressure in response to the pressure drop across said orifice, thereby unloading the cheek plate and directly by-passing the outlet portions of the pump to the inlet portions adjacent the sealing face of the cheek plate.

Claim 30

In combination, a pump having housing means forming a pumping chamber having inlet and outlet portions, rotary fluid displacement means in said pumping chamber for moving the fluid at increased pressure from the inlet to the outlet portions, a cheek plate adjacent said pumping chamber having a sealing face for sealing the inlet and outlet portions during operation of the pump, means including said housing forming a pressure control chamber behind said cheek plate to load said cheek plate with fluid at pump-generated pressure, means including said housing forming a return line for said pump receiving spent fluid returned to the pump, means forming an orifice in said return line and through which spent fluid is directed on the return line side of the pump, and a servo valve controlling a passage in said housing venting said pressure control chamber to a zone at lower pressure in response to the pressure drop across said orifice, thereby unloading the cheek plate and directly by-passing the outlet portions of the pump to the inlet portions adjacent the sealing face of the cheek plate.