Abstract: A hydraulic pump with a falling characteristic curve in respect of the output flow relative to the pump speed. A flow control valve (40) has a spool (41) with a hollow (50) extension portion (49), and an annular chamber (52) with two control edges (53, 56) which co-operate with the valve output duct (38) and a relief duct (19) to form restrictor means which are in opposition to each other. The valve output duct (38) and the relief duct (19) are disposed substantially radially with respect to the spool.

Abstract: An axial flow helical screw compressor with a slide valve and slide stop mounted end to end in communication with the intermeshing rotors has means for changing the volume ratio during operation by stepwise movement of the slide stop and for changing the capacity during operation in infinitely variable fashion, both in response to system operating conditions. In the event of interference between the movements of the slide stop and slide valve, the components are designed so that the movements of the slide stop overpowers that of the slide valve.

Abstract: A hermetically sealed rotary refrigerant compressor, comprising a compression chamber, a roller eccentrically rotatable in the chamber, and a vane slidably mounted in a slot in the wall of the chamber dividing the chamber between a low pressure suction side and a high pressure compression side including means for modulating the pressure differential between the low pressure suction side and the high pressure compression side of the vane at a preselected time in the compression cycle so as to minimize the frictional forces between the vane and vane slot caused by the pressure differential in the chamber.

Abstract: A scroll type compressor is disclosed which includes a housing with an inner chamber and fluid inlet and outlet ports connected to the inner chamber. A fixed scroll, which is mounted within the housing, has a circular end plate from which a first spiral wrap extends. An orbiting scroll also is mounted within the housing for orbital motion with respect to the fixed scroll. The orbiting scroll has a circular end plate from which a second spiral wrap extends; the first and second wraps interfit to define at least one pair of sealed off fluid pockets. The end plate of the fixed scroll partitions the inner chamber of the housing into a suction chamber and rear chamber. The rear chamber is divided into a discharge chamber and an intermediate pressure chamber. The circular end plate of the fixed scroll has at least one pair of holes symmetrically positioned to connect the sealed off fluid pockets to the intermediate pressure chamber.

Abstract: A hydraulic rotary vane pump comprises a flow control valve with a venturi throat disposed upstream thereof whereby the entire delivery flow from the pump passes through the venturi throat. The flow control valve is operable to control the amount of fluid flowing to the delivery outlet of the unit, under the influence of the pressure drop at a restrictor throttle in the form of a bore extending from the throat transversely with respect to the axis thereof. The angle between the axis of the venturi throat and the axis of the bore is between 90.degree. and 150.degree. depending on the degree to which the characteristic of the outlet flow produced is intended to drop off.

Abstract: An electrohydraulic compact drive for turbomachine valves includes: a device for supplying electric power, receiving electrical addressing signals and converting the signals into positioning and control variables; an hydraulic supply system including a fluid tank, pump, motor, accumulator and manifold; an hydraulic power piston/cylinder system including a piston rod connected to a valve, and a spring biasing the piston; an electrohydraulic addressing system generating a pressurized fluid flow opening the valve spindle against the spring dependent upon the variables; control members of the addressing system, the power system and the supply system forming a compact drive block at a valve; the pump being switched as a function of a pressure limit by intermittent charging and discharging operations between the charging pressures; the pump charging the accumulator in charging operation until the upper pressure is reached and, after being switched, returning the fluid to the tank in substantially pressureless circu

Abstract: A rotary-vane compressor wherein the pump housing is formed with a first by-pass passage which is open at its one end to the first intake port of the two intake ports which are open to the pump chamber formed in the rotor and at its the other end with the high-pressure chamber formed in the main housing, and provided with first by-pass valve means so that the first by-pass passage is opened when an external signal is supplied, and the first ring plate mounted on one side of the cam ring is provided with an one-way flow check valve to block fluid communication between the first intake port and the low-pressure chamber to which a new refrigerant is conducted, only when the first by-pass passage is opened.

Abstract: A rotary screw gas compressor for a refrigeration system comprises a motor-driven single main rotor having helical grooves and mounted for rotation in a rotor bore in the compressor housing and a pair of star-shaped gate rotors rotatably mounted in the housing and engageable with the helical grooves to define a plurality of compression chambers. A suction slide valve member is slidably positionable (between full load and unload positions) to control where low pressure uncompressed refrigerant gas from a suction port is admitted to the compression chambers to thereby function as a suction bypass to control compressor capacity. A discharge slide valve member is slidably positionable (between minimum and adjusted volume ratio positions) to control where high pressure compressed refrigerant gas is expelled from the compression chambers to a discharge port to thereby control the volume ratio and thereby the input power to the compressor.

Abstract: A rotary screw gas compressor for a refrigeration system comprises a motor-driven single main rotor having helical grooves and mounted for rotation in a rotor bore in the compressor housing and a pair of star-shaped gate rotors rotatably mounted in the housing and engageable with the helical grooves to define a plurality of compression chambers. A suction slide valve member is slidably positionable (between full load and unload positions) to control where low pressure uncompressed refrigerant gas from a suction port is admitted to the compression chambers to thereby function as a suction bypass to control compressor capacity. A discharge slide valve member is slidably positionable (between minimum and adjusted volume ratio positions) to control where high pressure compressed refrigerant gas is expelled from the compression chambers to a discharge port to thereby control the volume ratio and thereby the input power to the compressor.

Abstract: A variable volume ratio screw compressor has a side load inlet port for the injection of refrigerant vapor into the interlobe volume. In order to improve efficiency, overcompression and undercompression are avoided by varying the location of the radial discharge port to give the compressor an internal volume ratio matched to the pressure of the system in which the compressor operates. This is accomplished in the present application by locating a pressure sensing port no earlier than and preferably later in the compression than the side load injection port, but early enough in the compression that it will not communicate with the discharge port. The pressure that is sensed in the sensing port is used to predict the actual peak pressure in order that maximum efficiency may be obtained as a result of matching the internal volume ratio to the pressure ratio of the system.

Abstract: A vane type rotary pump comprises a cam ring mounted within a stator housing and having an inner peripheral wall defining four circumferentially equi-spaced semicylindrical inner cam surfaces, a pair of end wall structures fitted to opposite ends of the cam ring to form a pump cavity, a drive shaft rotatably mounted within the stator housing, a rotor contained within the pump cavity and mounted on the drive shaft for rotation therewith, and a plurality of circumferentially equi-spaced vanes slidably fitted in the body of the rotor to cooperate with the inner cam surfaces to form four pairs of suction and delivery chambers.

Abstract: Hydraulic fluid supply system for supplying high pressure hydraulic fluid to power actuators for power steering systems includes a pumping mechanism having independent pumping chambers adapted to discharge fluid to a supply line leading to the power actuator. The supply line contains a variable orifice and a flow control valve responsive to the pressure difference generated by the variable orifice. The pumping chambers include at least first and second pumping chambers connected to first and second feed lines. A switching valve operatively interconnected to the variable orifice and actuated by an electrically operable drive mechanism selectively connects the second feed line to the supply line or to the first feed line.

Abstract: A screw compressor having two rotors (2,3) rotatably journalled for mutual meshing engagement in a respective working chamber (4,5) of a compressor housing (1). For the purpose of regulating the pressure ratio and the capacity of the compressor, a composite slide assembly comprising two slides (17,18) is mounted for axial movement in a recess (6) in the housing (1), the composite slide having two flanks which form a continuous wall in the two working chambers (4,5). The two slides are individually movable and, for the purpose of improving the regulating function one of the slides (18) is provided with a flank which forms a wall of the working chamber (4) of solely one rotor, preferably the male rotor (2).

Abstract: Controls for a dual element pump having first and second pumps with separate outputs wherein a modulating valve is positionable to control the amount of fuel delivered by a first pump to a fuel control and additionally to selectively control the utilization of flow delivered by the second pump. The flow from the second pump is bypassed when not needed through a pressure regulating valve having a minimal setting and with the setting of the pressure regulating valve being increased by operation of the modulating valve prior to the flow from the second pump being added to the flow from the first pump. The control of the modulating valve is by means of a flow control valve operating through dynamic compensator structure. The flow control valve is positioned by a head sensor including a jet pipe shiftable from a null position by a pressure differential signal delivered by two pressure sensing lines sensing a pressure differential across a variable area opening in a valve forming part of the fuel control.

Abstract: A space conditioning closed loop refrigeration system, particularly a vehicle air conditioning system utilizing a positive displacement compressor having a slide valve for varying the capacity and shiftable between full load and full unload positions and vice versa and driven therebetween by a linear fluid motor having a movable member coupled to the slide valve and forming a first chamber which is normally dumped via a slide valve modulator to compressor suction pressure and a second chamber open to compressor discharge pressure. A restricted passage between chambers tends to cause the first chamber to reach compressor discharge pressure absent that chamber dumping to suction.

Abstract: An automotive air conditioning system has refrigeration devices, heating devices and a single chip microcomputer. The refrigeration devices include a variable displacement refrigeration compressor drivingly connectable by an electromagnetic clutch to an automotive engine and a refrigerant evaporator disposed in an air duct, through which air is caused to flow by a blower. The heating devices include a heater core disposed downstream of the refrigerant evaporator, through which heated air is caused to flow, and an air mixing damper which regulates the quantity of air to be introduced into the heater core. A condition relating to the air conditioning operation such as the temperature of the vehicle is detected by a sensor. The microcomputer receives the signals from the sensor, calculates a required injection temperature, compares the required injection temperature and a preset standard temperature, a lower standard temperature and a higher standard temperature and produces operating signals.

Abstract: A high-pressure refrigerant driven refrigeration apparatus has a heat exchanger charged with a refrigerant for transferring heat from a heat source to the refrigerant, and a refrigerant motor connected to the heat exchanger and powered by the heated high pressure refrigerant. A compressor is connected to the refrigerant motor and driven thereby. The system includes a condenser connected to the refrigerant motor and to the compressor for liquefying the refrigerant from the refrigerant motor and from the compressor and an evaporator connected to the compressor for receiving the expanded refrigerant from the compressor. The refrigerant motor may be a reciprocating or a rotary motor.

Abstract: In a rotary vane pump having a normally vertical suction feed flow passage (17a, 17b) which opens tangentially into a horizontal, elbow-bent feed passage (18a, 18b) and a discharge passage (19a, 19b), the direction-changing portion is formed by a plug-like insert (51) which is pressed into a stepped bore (61). The insert (51) comprises erosion-resistant material.

Abstract: A rotary compressor for compressing a refrigerant gas has a by-pass port and a control valve means. The by-pass port communicates at one end with a suction chamber containing the gas to be compressed, and at the other end with a compression chamber wherein compression of the refrigerant gas is in progress. The control valve means includes a valve spool accommodated in a chamber formed in a front side plate of the compressor and movable between its full-load position, where a gas suction port is opened to the compression chamber while the by-pass port is closed, and its partial-load position where the former is at least partially closed while the latter is opened. The valve spool is normally biased to its partial-load position. During operation of the compressor, the valve spool is placed under the influence of a first pressure of the gas acting to urge the same towards its said full-load position, and to a second pressure of the gas to urge the same towards its said partial-load position.

Abstract: A vane pump having a flow regulating bypass valve activated by outlet pressure to direct excess flow back to the inlet is provided with a channeling having an element comprising a plug insertable in the valve housing, which plug has a specially shaped flow bend in the form of an arcate groove that forms a smooth transition for combined flow from a tank fed inlet and from the bypass valve to the pump inlet. This is effected by connecting a channel from the tank inlet and bypass valve to a channel for flow return to the pump inlet which channels are angularly related. Since the valve housing is die cast the difficulty of providing, in a casting, an exactly shaped smooth surfaced and accurately dimensioned transition passage between the aforementioned channels is overcome by the invention.

Abstract: The compression capacity of a rotary compressor may be changed by a cylinder bypass system. The change of compression capacity is achieved by a slide wall member which composes part of an inside wall of a cylinder containing a compression mechanism and which is movable, thereby bypassing gas being compressed to a suction side of the compressor. The slide wall member is caused to slide forward by gas pressure applied and to slide backward by a spring force. By controlling such gas pressure, the capacity of the compressor may be changed. A relatively large opening is formed in the cylinder when the slide wall member is moved backward, so that the compression capacity can be greatly reduced without a large decrease in efficiency.

Abstract: A compressor bypass passage has an inlet portion and an outlet portion which is connected to the suction passage. The inlet portion of the bypass passage has an opening which is able to be open to the compression chamber when the compression chamber is in a decreasing volume stroke, thereby to spill the refrigerant from the compression chamber into the suction passage. A control pressure chamber is formed in the housing. A valve member is arranged in the inlet portion of the bypass passage. The valve member is actuated in response to a variety of pressures of the refrigerant in the control pressure chamber for adjusting the area of the opening of the inlet portion of the bypass passage. A pressure supply passage for supplying a refrigerant, which pressure is higher than the pressure in the suction passage, is connected to the control pressure chamber. A spill passage for spilling a part of the refrigerant interconnects the control pressure chamber to the suction passage.

Abstract: A positive displacement rotary compressor includes a stator which contains a rotor and has a stator inlet communicating with atmosphere via a first pilot operated valve and a stator outlet connected to a primary lubricant reservoir via a non-return valve and to an auxiliary lubricant reservoir via a second pilot operated valve and one or more lubricant injection orifices arranged to inject oil into the stator and connected to the primary reservoir via a third pilot operated valve and to the secondary reservoir. The compressor also includes a pilot control system responsive, in use, to the compressed air load to which the compressor is subjected and arranged to switch the first and third pilot operated valves from an open position to a closed position and the second pilot operated valve from a closed position to an open position when the compressed air load falls below a predetermined value. The auxiliary lubricant reservoir is always at substantially atmospheric pressure.

Abstract: A rotary slide vane pump for steering booster systems has a flow control valve which bypasses flow from outlet side to suction side with increase in speed as heretofore known. The flow channels or passages that conduct bypass flow change the direction of the flow at a juncture point between passages, such directional change being a right angle, radially downstream from the bypass valve to longitudinally at the point of juncture to the suction side, likewise as heretofore known. In the present invention there is provided a transition piece between the channels at the right angle juncture in the form of a screw in the pump body and having a flat face disposed flush with the longitudinal channel and transversely of the radial channel. The provision of such transition piece has been found to effect an increase in suction pressure when bypass flow is added to normal suction flow, such increase being over and above that effected by the prior art.

Abstract: A capability control apparatus for a compressor wherein gas sucked into a compression chamber is compressed due to a decrease in volume of the compression chamber. The pressure of the gas sucked into the compression chamber, in response to an increase or decrease in load, is automatically controlled by varying the volume of the compression chamber based on the pressure of the sucked gas.

Abstract: A gerotor pump of n and n+1 type has the annulus and rotor located in a chamber with one wall provided by a floating coverplate held in place by a spring so that in the event of excess internal pressure the cover can lift to allow cross leakage between the inlet and outlet sides of the pump. FIG. 2 illustrates a typical embodiment.

Abstract: The shaft coupling a reciprocating piston of a fluid motor to a slide valve shiftable longitudinally along a screw compressor housing and varying the amount of compressor suction gas returned to the suction port for varying compressor capacity constitutes an outer hollow tube having a smaller diameter indicator shaft mounted axially therein. The shaft carriers a helical V-groove on its exterior surface and a spring biased pin projecting radially inwardly from the outer tube rides in the helical groove such that, as the slide valve reciprocates, driven by the fluid motor piston, the indicator shaft is rotatably driven about its axis. Multiple cams fixed to the indicator shaft and rotatable therewith actuate juxtapositioned microswitches to indicate full load position, full unload position, and two intermediate load positions for the slide valve. The indicator shaft is directly axially connected to a potentiometer to provide an electrical analog output signal.

Abstract: A regulatable vane pump is provided with regulating apparatus incorporated in the pump having a differential pressure piston operable responsive to booster steering flow demand wherein the piston carries a flexible leaf spring having a flat surface which serves as a shut off member against ports in a restrictor member. Actuation of the regulating piston carries the leaf spring toward the ported member to progressively shut off restrictor ports in the face of the ported member, either partially or fully depending upon the ported arrangement. As ports are gradually closed off regulation of the pump discharge is effected at various demand pressures after linear rise of rate of discharge up to a regulating point. Thereafter, there is wide separation of characteristics of regulating curves or lines for differing pressure demands. The overall effect produces a precise regulation within narrow limits as well as an economy of manufacture.

Abstract: An electro-hydraulic unit for control devices, particularly for steering devices, braking devices, suspension devices, and like devices comprises an electric motor directly connected to a gear hydraulic pump, said electric motor and hydraulic gear pump having a common interface providing a lateral cheek for the electric motor, this common interface being formed in one part with body of the hydraulic pump.

Abstract: A rotary pump for pumping liquid which includes a rotor combination in the form of a vane pump or gear and rotor with pumping chambers disposed circumferentially around the rotor. The chambers progressively increase in the inlet area and ensmall in the outlet area. Pulse absorbtion means are interposed in the fuel passage means to absorb pulses and smooth out the pressurized outlet liquid, thus reducing the pump noise under all conditions of operations.

Abstract: An axial flow helical screw type compressor has a slide valve member and slide stop member mounted end to end beneath the intermeshing rotors such that the slide valve member controls communication between the work chamber defined by the rotors and the casing to the outlet port and the slide stop member and the valve member together control the working fluid inlet to the bores of the rotors, the slide valve member and the slide stop being independently movable. Control means for the slide valve member and slide stop include position sensing means for these two members, inlet and outlet pressure sensing means, and means for feeding these inputs into programmable circuitry to control the positions of the slide member and slide stop.

Abstract: An axial flow helical screw type compressor has a slide valve member and a slide stop member mounted end to end beneath the intermeshing rotors such that the slide valve member controls communication between the work chamber defined by the rotors and the casing to the outlet port and the slide stop member and the valve member together control the working fluid inlet to the bores of the rotors, the slide valve member and the slide stop being independently movable. Control means for the slide valve member and slide stop include position sensing means for these two members, inlet and outlet pressure sensing means, and means for feeding these inputs into programmable circuitry to control the positions of the slide member and slide stop.

Abstract: An automatic variable volume ratio screw compressor has a plurality of ports for the injection of liquid refrigerant into the interlobe volume. These ports communicate with the interlobe volume at different effective distances from the discharge port so that the injection of liquid refrigerant may be done at the latest possible time during compression for effective use of the refrigerant, and without risking exposure to the open discharge port.The selection of the port is done automatically in response to the instantaneous internal volume ratio.

Abstract: A modular three block assembly provides unloading control for a hydraulic cylinder functioning to variably position a slide valve on a helical screw rotary compressor. A first compressor block is fixedly and sealably mounted within the hermetic compressor outer casing and has through holes leading to a first tube connected to a source of oil under discharge pressure forming the hydraulic fluid for the hydraulic cylinder, a second tube connected to the hydraulic cylinder and a third tube to the suction tube returning low pressure vapor to the compressor suction side. A needle valve block is fixedly mounted to the external face of the compressor block and bears within longitudinal through passages paired needle valves determining the load and unload flow rates for the hydraulic fluid passing through said compressor block through holes.

Abstract: A turbocharged internal combustion engine, preferably of the two-stroke cycle type, is provided with a Roots type positive displacement charging blower having a bypass passage in one end plate and controlled by a single plunger control valve responsive solely to blower outlet pressure to provide for bypassing air flow around the blower under various engine operating conditions either in reverse direction to reduce excess blower power or in the direction of flow to provide additional charging air.

Abstract: A rotary compressor is provided with a rotary valve arranged rotatably in the housing unit. The rotary valve is partially exposed to an interior space of the housing unit. The interior space is divided into a plurality of variable working spaces. A return port is formed in the rotary valve for feeding a cooling medium into an inlet port from the working space. A quantity of the cooling medium discharged from the working space through an outlet port is changed in accordance with the rotation of the rotary valve controlled by the actuator.

Abstract: The invention relates to a valve arrangement for capacity control of an oil-injected screw compressor. One or more piston valves are arranged one after the other in the axial direction of the rotors at the portion of the rotor barrels where the internal compression phase occurs. The compressor control valves are actuated by the discharge pressure, which in their turn open or close the piston valves. When the piston valves are open, a portion of the gas in the compression space is discharged to a bleed off passageway and it flows back to the inlet port of the compressor so that substantially no compression work is spent on this portion of the gas.

Abstract: A vane-type compressor of the lubrication type in which pressure applied to vane bottoms is controlled to prevent vane breakage and excessive wear. A rotor is disposed between a rotor housing and a pair of side housings with vanes slidingly disposed within corresponding vane grooves radially formed in the rotor. Intake fluid pressure is applied to spaced defined between each of the grooves and the bottom of the corresponding vanes during suction strokes through a first arcuate groove. A second arcuate groove is formed in an inner surface of the side housings at a position corresponding to the spaces during compression strokes. A pressure discharge passage connected to the arcuate groove and an outlet port is provided and a check valve is provided in the pressure discharge passage.

Abstract: There is disclosed a scroll-type machine specifically suited for use as a gaseous fluid compressor. The machine has intermediate relief valve means providing variable pressure ratio characteristics to thereby improve efficiency, as well as protect against overcompression.

Abstract: A vane type pump with a variable capacity for power steering devices is provided with a movable ring received and radially movable in a closed cylindrical bore of a pump housing. A spring acts on the movable ring to deflect the axis of the movable ring from the axis of a rotor, which is rotated to move vanes along an internal bore of the movable ring. A sealing pin and a valve element are provided at diametrically opposite sides of the movable ring and define first and second pressure chambers around the movable ring. The first pressure chamber receives pressurized fluid from a part of the internal bore of the movable ring and conducts the pressurized fluid into the second pressure chamber through a throttle, which is defined by the valve element and a part of a circumferential external surface of the movable ring. The throttle generates a pressure difference between the first and second pressure chambers, and the pressure difference acts on the movable ring to move the same against the force of the spring.

Abstract: A hydraulic motor which varies its displacement in accordance with varying torque loads on its output shaft. The motor is biased to a low displacement, low torque, high speed mode, and changes to a high displacement, high torque, low speed mode when the torque load on its output shaft increases. The motor has eccentrically disposed gerotor gears that rotate and orbit relative to each other to expand and contract fluid chambers on opposite sides of a center line of eccentricity. The gerotor gears can change their orientation relative to each other in response to changes in the torque load on the output shaft, changed, in order to change the displacement of the motor.

Abstract: A hydraulic power steering system has a vane type pump which is operable to supply fluid to a power steering gear at a volumetric rate determined in part by the system pressure requirement or system demand. The pump flow is partially bypassed through an aperture in the cam ring at low system pressures. The bypass flow is controlled by a sleeve valve surrounding the cam ring and being subjected to system pressure to incrementally close the aperture and reduce bypass flow and simultaneously increase the output flow. At a predetermined system pressure, the valve is moved sufficiently to control reopening of the aperture for controlled bypass flow to limit the maximum system pressure.

Abstract: A refrigeration system for use in an automotive air conditioning system has a vane type variable displacement refrigerant compressor drivingly connectable by an electromagnetic clutch to an automotive engine and a refrigerant evaporator through which air is caused to flow by a blower. The compressor is provided with one or two unloading ports for releasing the refrigerant being compressed and with a valve member or members associated with the unloading port or ports. The air temperature just downstream of the evaporator is detected by a sensor which emits a signal to an electric circuit for actuating the valve member or members so that the unloading port or ports are selectively opened to vary the compressor displacement to provide a multistage compressor displacement control. The electric circuit is also operative to control the electromagnetic clutch to selectively connect and disconnect the compressor to and from the engine.

Abstract: In an oil pump having two pump cartridges each acting as independent pumps, a pair of suction passages and a pair of discharge passages opened in a pair of pump chambers in the pump cartridges are formed in one pump body secured to one side of the cartridges, a flow control valve is contained in an opening extending in an axial direction of the pump body, and a pressure sensitive flow passage change over valve is contained in another valve opening perpendicular to the valve opening. The two valve openings are communicated with the discharge and suction openings.

Abstract: A hydraulic power steering system has a vane type pump which is operable to supply fluid to a power steering gear at a volumetric rate determined in part by the system pressure or system demand. The pump flow is partially bypassed through a valve member which is slidably disposed in the thrust plate of the pump. The thrust plate has a bypass aperture which communicates between the pump discharge and the pump inlet. The valve member is spring loaded to permit fluid communication through the apertures and is pressure biased by increasing system pressure to reduce the bypass flow and thereby increase system discharge flow.

Abstract: In a vacuum pump having a housing presenting a suction side and a pressure side, a connecting line connected between the suction side and the pressure side and a weighted valve mounted in the connecting line and having a part which is movable to open the valve in order to place the suction and pressure sides in communication when a maximum permissible pressure difference between the suction and vacuum sides is exceeded, the valve is mounted so that the axis of movement of the valve part forms an angle of 45.degree. with the direction of the pumping action between the suction and pressure sides, whereby the weighted valve will function properly with the pump oriented to produce its pumping action in either the vertical or the horizontal direction.

Abstract: A hydraulic power steering system has a vane type pump which is operable to supply fluid to a steering gear at a volumetric rate determined in part by the system pressure or the system demand. The vane pump flow is partially bypassed through a valve member disposed in the end cover and thrust plate of the pump. The valve is rotatably disposed in the end cover and spring loaded therein to a position which permits direct fluid communication between the pumping chambers and the pump inlet. The valve member has a portion thereof operated on by system pressure which is operable to close the bypass passages with increasing system pressure such that pump discharge flow to the power steering system will increase. The valve member can be moved sufficiently in response to system pressure to reopen the bypass passages thereby providing a limiting value for maximum system pressure.

Abstract: A hydraulic power steering system has a vane type pump which is operable to supply fluid to a steering gear at a volumetric rate determined in part by the system pressure or system demand. The pump flow is partially bypassed through a valve member disposed in the cam ring at a position adjacent the pumping chambers. The valve is spring loaded radially inward to permit the bypass flow at low system pressure levels. Increasing system pressure levels bias the valve member radially outward thereby reducing bypass flow while simultaneously increasing pump discharge flow. At a predetermined pressure level, the valve member will reach a secondary opening position to bypass fluid flow and thereby limit the maximum system pressure.

Abstract: A hydraulic power steering system has a vane type pump which is operable to supply fluid to a power steering gear at a volumetric rate determined in part by the system pressure or system demand. The flow from the pumping chambers is partially bypassed through a bypass passage formed between the cam ring and the pump thrust plate. The bypass passage is urged to the open position by a bypass spring which urges separation between the cam ring and the thrust plate. The pressure plate of the pump responds to system pressure or demand to urge the cam ring into abutment with the thrust plate thereby reducing the opening and decreasing the bypass flow.

Abstract: A rotary vane pump, in particular for steering assistance, comprising a rotor (7), a cam ring (5) and a pressure plate (4). The housing (1) has two parallel bores (17a, 17b) and cast passages (18a, 18b) as feed passages which each split up into two flow paths (23, 24) in the region of the pressure plate (4) and the cam ring (5). The outlet passages (31, 32, 33) are of a similar configuration.