Abstract: The present invention provides a check valve which, when placed at the end of a pump suction pipe, allows the pump to draw fluid therethrough from a continuously replenished, below-ground fluid source. When the fluid in the fluid source has been depleted to a level below that which allows fluid to be drawn therefrom by the pump, the present check valve maintains the suction pipe full of fluid. The check valve also maintains the suction pipe full of fluid when the pump has been shut off. In this manner, the pump can resume drawing fluid from the fluid source without the need for priming.

Abstract: A hydraulic pump of the rotary vane type comprises a first throttle bore and a second throttle bore disposed in parallel between a pressure chamber of the pump and a delivery passage, and a variable flow throttle valve is provided which is responsive to a difference between a vane back-up pressure and a pressure within the delivery passage to vary an opening degree of the first throttle bore.

Abstract: A rotary-vane pump has a pump outlet, a pressure chamber of the pump, a flow control valve, and a throttle disposed between the pump outlet and the flow control valve. According to the present invention, the throttle is formed by an insert which is disposed in a pressure passage between the pump outlet and the flow control valve. Specifically, the pressure passage is disposed between the pump outlet and the pressure chamber, and the insert is hollow cylindrical and has an axial bore having one axial end portion disposed on the pressure passage. The insert is disposed in the pressure passage at an angle approximately 90.degree. in relation to the inflow direction of pressure medium in the passage.

Abstract: The first of two serially arranged electromagnetically operated spool type drain control valves is conditioned to select the drain passage of smaller the pump before the second valve is moved from its closed or communication cut-off position, to its open position wherein hydraulic fluid can be drained therethrough, whereby the spool of the second valve is exposed to a relatively small flow generated force which acts thereon and which tends to move the valve spool toward to its closed position. In another embodiment the hydraulic fluid temperature is monitored and used to modify the control schedule via which the switching of the drain control valves is determined. A further embodiment monitors a parameter which is indicative of the prime mover rotational speed and inhibits the closure of the second of the two valves when the rotational speed is above a predetermined limit.

Abstract: Method and apparatus for operating a compressor to avoid surge conditions. The compressor is controlled by determining a surge line for the compressor as a function of compression ratio and the flow coefficient (M.sqroot.RTZ)/P.sub.s ; measuring the differential head, h, across a flow element, the suction pressure, P.sub.s, and the discharge pressure, P.sub.d ; generating a process signal that is a function of P.sub.d /P.sub.s and .sqroot.h/P.sub.s and comparing the process signal with a set point signal to control recycling of discharge flow to the inlet flow to prevent operation of the compressor in surge conditions.

Abstract: A power steering pump includes a housing defining an opening containing a sliding vane rotor, a cam ring and pressure plates located at each axial side of the rotor, inlet ports connected to a source of low pressure fluid, and outlet ports connected to a power steering system. The pressure control valve opens and closes an orifice of constant size connecting the pump outlet to a power steering gear. An electronically variable orifice arranged in parallel with the fixed orifice connects the pump and outlet to the power steering gear. When the control valve opens sufficiently, the pump outlet is connected to the inlet through a diffuser arranged to draw low pressure fluid into a high velocity stream of bypass fluid. An orifice fitting, located in a flow control valve that directs flow from a pump outlet port through the orifice aperture to an automotive power steering gear, diverts that flow to a bypass port connected to the pump inlet. The orifice aperture is offset radially from the axis of the valve.

Abstract: A power steering motor is operatively connectable with steerable vehicle wheels for steering the vehicle wheels. An actuatable power steering valve has a neutral position in which fluid flows through the steering valve to a fluid reservoir and an actuated position in which fluid flows through the steering valve to the steering motor. A main conduit conducts fluid from the outlet port of a pump to the steering valve. A return conduit conducts fluid from the steering valve to the reservoir when the steering valve is in its neutral position and in its actuated position. An orifice is located in the return conduit. A bypass valve bypasses fluid from the main conduit to the reservoir. The bypass valve is controlled in response to a pressure drop across the orifice located in the return conduit.

Abstract: The flow control system includes a flow control valve, an orifice located between the pump outlet port, a passage carrying feedback pressure at a location downstream from the orifice to one side of the valve, and a bypass port located between the pump outlet and the pump inlet. The bypass port opens as a valve spool moves due to differential pressure across the orifice. When pump discharge is low, the valve closes the bypass port; when pump flow rate increases, the valve opens the bypass port. The jet pump effect of a bypass diffuser, located between the bypass port and the pump inlet, supercharges low pressure fluid in a remote reservoir by using kinetic energy in the bypass flow to draw fluid from the reservoir into the pump and to raise static pressure at the pump inlet. A clip having a relatively large wetted surface area in comparison to its cross sectional area is located in a passage connecting the pump outlet and the load.

Abstract: A power steering pump includes a housing defining an opening containing a sliding vane rotor, a cam ring and pressure plates located at each axial side of the rotor and having inlet ports connected to a source of low pressure fluid and outlet ports connected to a power steering system. The pressure control valve opens and closes an orifice of constant size connecting the pump outlet to a power steering gear. An electronically variable orifice arranged in parallel with the fixed orifice connects the pump and outlet to the power steering gear. When the control valve opens sufficiently, the pump outlet is connected to the inlet through a diffuser arranged to draw low pressure fluid into a high velocity stream of bypass fluid. Kinetic energy of the stream is used to increase static pressure in the fluid supplied to the pump inlet.

Abstract: An antisurge apparatus for eliminating surges in compressed air output by a compressor. The compressed air output by the compressor is divided into a first portion of compressed air being supplied to a dump tube for dumping the first portion of compressed air as excess compresssed air to avoid surge and a second portion of compressed air being supplied to apparatus which makes use of the compressed air. The antisurge apparatus includes apparatus for sensing a change in flow of the second portion of compressed air output by the compressor and supplying a flow change signal proportional to flow indicating the amount of the change in flow and apparatus for controlling the amount of the first portion of compressed air being supplied to the dump tube in response to the flow change signal. The antisurge apparatus eliminates compressor surges while minimizing the amount of air dumped as the system or apparatus demand for compressed air increases.

Abstract: A fluid pump has a pressure chamber communicated with a discharge outlet via an orifice. A pressure difference responsive flow control valve is also provided for adjustment fluid flow rate through the discharge outlet. The flow control valve has a valve spool housed within a spool chamber. The spool chamber has one end directly opening to the pressure chamber.

Abstract: Disclosed is a coating apparatus, comprising a gas exhaust rate controller disposed within an exhaust pipe connected to a cup which houses a substance to be treated, and a branch pipe connected to the exhaust pipe. The flow speed of the fluid within the branch pipe is measured, and the driving of the exhaust rate controller is controlled based on the measured value of the flow speed in accordance with the state of treatment of the object to be treated.

Abstract: A power steering system includes a bypass valve for bypassing fluid from a main fluid conduit connected between an engine-driven, power steering pump and an actuatable, open-center, steering control valve which is actuated upon turning of a vehicle steering wheel. When the steering control valve is actuated, the demand for fluid through the steering control valve to a power steering motor increases. The fluid pressure in the main conduit varies as a function of the demand for fluid to the steering control valve. The bypass valve is urged toward an open condition by a fluid pressure signal. The bypass valve is urged toward a closed condition by a spring and by a fluid pressure which varies as a function of the demand for fluid to the steering control valve and as a function of an electrical signal which varies as a function of at least one vehicle operating parameter, such as vehicle speed.

Abstract: An energy conservation apparatus for controlling the operation of a recirculating hot water distribution system which comprises of a hot water heater (15) having an outlet (17) and an inlet (16); a return pipe (24) interconnecting the end of the supply pipe back to a tee (25) on the makeup water inlet to form a loop; and an electrically operated recirculating pump (26) in the loop, usually on the return pipe, that circulates the hot water around the loop. Thus hot water is available anywhere in the system without having to first discharge any cooled hot water that has been standing in the piping. The invention consists of a sensitive flow sensor or usage detection device (33) located on the unheated makeup water supply and connected to a controller (34). The controller turns on the recirculating pump only when hot water is draw from any of the usage points. The invention saves energy by reducing the heat loss from the hot water distribution system.

Abstract: A peristaltic pump controller provides control of a positive displacement pump as either an uncalibrated or calibrated flowmeter, or a calibrated dispenser. A calibration constant is calculated, after the pump is primed, to determine the amount of volume output produced by an increment of angular rotation of the pump. The constant is determined during a calibration operation where an arbitrary calibration volume is metered. The controller has a low flow and high flow mode where the low flow mode provides a higher resolution for dispensing. The flow mode of operation is determined by the value of the calibration constant and is automatically set when the constant is calculated. DUring a dispensing operation, the controller will meter fluid to within a predetermined amount of the final volume dependent upon the speed of the pump motor and then dribble in the remaining amount of a batch for precision.

Abstract: A flow control valve includes a cylinder in which an inflow port, an outflow port and a return port are formed. A spiral choke is formed between the inflow and outflow ports. A working oil introduced from the inflow port into the cylinder flows out from the outflow port through the spiral choke. An actuating valve is arranged in the cylinder so as to open and close the return port in accordance with a difference in pressure between the inflow and outflow port sides of the spiral choke. When the pressure difference exceeds a predetermined value, the actuating valve opens the return port so that a part of the working oil introduced into the cylinder is returned to the inflow side of the flow control valve.

Abstract: A self contained mechanical bleed control apparatus for a fluid conveying system, such as a central vacuum system or a pressurized air system, includes a slide member housing which slidably supports an orifice plate having an air foil on one end disposed within a main flow conduit just upstream from a vacuum producer or downstream from the compressor in a pressurized fluid system. A source of bleed fluid communicates with the slide member housing and is valved by movement of the orifice plate. The orifice plate is biased to a position for communication of bleed fluid into the main conduit under low flow conditions. Increased flow through the main conduit acts on the air foil to slide the orifice plate against the urging of the biasing force to cut off the bleed fluid supply.

Abstract: An airflow control system generates a compensating output which is combined with the normal damper control output in a damper operating device when a pole change motor driving a blower changes speed so that the damper is changed to compensate for the change in blower speed to avoid a large change in airflow. This overcomes the delay in the normal integrating damper control which produced unwanted fluctuation in airflow when the motor speed was changed.

Abstract: A steering power-assistance pump of vane type includes a combined flow control and pressure relief valve. When the steering valve of the steering arrangement shuts off the flow of oil, the output of the pump is converted into heat within the pump which accordingly suffers a substantial rise in temperature. The rotor of the pump and the cam ring with which the rotor vanes co-operate are combined with a pressure plate and a wear plate on respective sides of the rotor to form a unit which is displaceable in the axial direction of the pump against the force of a compressible sealing means for sealing off inlet ducts relative to a pressure chamber behind the pressure plate. The unit is thus displaced against the force of the compressible sealing means, as a result of thermally induced deformation of the housing portions of the pump. The wear and pressure plates have coatings of bearing metal on their surfaces which co-operate with the rotor, to provide better anti-friction properties.

Abstract: A power steering system includes a bypass valve assembly which bypasses fluid from a main conduit connected with a power steering pump and motor. The bypass valve assembly is urged toward an open condition, bypassing fluid from the main conduit, with a force which varies as a function of the fluid pressure drop across an orifice in the main conduit. The bypass valve assembly is urged toward a closed condition by a spring. In addition a pressure responsive pilot valve assembly opens to communicate the fluid pressure in the main conduit to the bypass valve to urge the bypass valve assembly toward the closed condition. This decreases the rate at which fluid from the power steering pump is bypassed to thereby increase the amount of fluid available for actuation of the power steering motor.

Abstract: A hydraulic control system having a supply of low pressure hydraulic fluid and a hydraulic pump having a fluid inlet and a fluid outlet through which fluid is delivered at a high operating pressure when the pump is pumping at its capacity. A valve is placed in fluid communication with the supply of hydraulic fluid and the pump fluid inlet for permitting fluid communication between the supply of hydraulic fluid and the pump fluid inlet when in one mode of operation and for substantially preventing fluid communication between the supply of hydraulic fluid and the pump fluid when in a second mode of operation. A control means prevents the valve from assuming its second mode of operation until the magnitude of the pressure at the pump fluid outlet is below a predetermined pressure. The predetermined pressure is set to be substantially below the pump operating pressure.

Abstract: A modular sub-assembly of a regulator of a pressure drop detector and intated excess speed governor intended for use with turbo-machines. The pressure drop detector and the excess speed governor are supplied in parallel by a common working fluid at a common pressure PF at low flow and the excess speed governor is capable of reducing the pressure of the working fluid by placing it in communication with a pressure PB which is higher when a predetermined excess speed is achieved, in order to reduce the pressure Pmod at the outlet of the pressure drop detector and to reduce the fuel flow delivered to the injector circuit of the turbo-machine.

Abstract: A rotary vane pump has a pressure operated valve to bypass pump outlet flow to the inlet of the pump for flow regulation. A metering throttle bore, downstream of a choke bore, responsive to viscosity is a passage from the pump to a consumer such as a servosteering system. Responsiveness to viscosity is effected by providing an area in cross section for flow passage in the metering bore, which flow area is much smaller than the wetted surface area of the passage. A pressure agent at a cold temperature having greater viscosity than that at a higher temperature will effect flow regulation of the pump sooner than the high temperature pressure agent. Since for a cold pressure agent the viscosity is higher, the resistance to flow through the metering throttle bore is greater. As a result, the pump must work at a higher pressure which actuates the pressure operated valve to effect bypass flow.

Abstract: A positive displacement pump for a vehicle power steering system comprising a rotor (42) rotatable in and cooperating with a stator (20) to define a pump cavity (52), (54), inlet and outlet ports (56), (58) and (34), (36) communicating with the pump cavity and a flow control valve (96) located in the flow delivery circuit wherein provision is made for opening the flow delivery circuit to a bypass circuit (72) upon an increase in the speed of the vehicle beyond a design point thereby reducing the pump back pressure and power usage which results in increased "road feel" at increased speeds while maintaining normal power assist during steering maneuvers at low speeds.

Abstract: A rotary vane-type gas compressor for use in car coolers and the like has a plurality of intake ports for each compression working chamber located at positions shifted from one another in the revolving direction of a rotor. At least one intake port which is located at the most forward position in the revolving direction of the rotor has a throttle valve which is controlled in response to the flow rate of suctioned gas, and the opening degree of the throttle valve is changed as the revolution speed of the rotor increases and creates a higher flow rate of suctioned gas. This reduces the effective compression working chamber volume, i.e., the volume which results when one vane has passed the position of the corresponding intake port to enclose gas in the compression working chamber. By such a construction, it is possible to restrain a substantial increase in both the amount of compressed gas to be discharged and the air-cooling capacity, even when the revolution speed of the rotor increases above 2000 rpm.

Abstract: A regulatable vane pump is provided with a piston operable by differential pressure responsive to booster steering flow demand wherein the piston movement controls a choke bore flow area. The differential pressure is effected by pump pressure on one face of the piston and consumer pressure on the opposite face of the piston, e.g., pressure in a booster steering servomotor. The choke bore has an aperture covered or uncovered by a choke plate carried by a pin on the piston. The choke plate is normally in position so as not to impede flow through the choke and the piston is in a position such that pump outlet flow is blocked from a bypass passage back to the pump inlet. However, with rise in vehicle speed under non-steering conditions, causing pressure on the one face of the piston to shift it along with the choke plate, the choke bore is closed, or partially so, and the unnecessary output pressure flow shunted back to pump inlet.

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: The duration of a pumping operation from a fixed supply of cryogenic liquid is extended by minimizing the amount of cryogenic liquid which is recirculated between a primary cryogenic pump and a storage tank for containing the cryogenic liquid. The primary cryogenic pump is characterized by a minimum necessary net positive suction head at its intake. The net positive suction head of the cryogenic liquid is directly measured at the inlet of the primary cryogenic pump by means of a differential pressure gauge. The total pressure on the cryogenic liquid at the inlet of the primary cryogenic pump is then maintained by means of a cryogenic booster pump to always exceed the measured vapor pressure at the inlet by an amount just equal to the minimum net positive suction head required by the primary cryogenic pump.

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: 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: 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 demand responsive flow regulator valve for use with a power steering pump and steering mechanism has a valve spool slidably disposed in a housing and responsive to a pressure differential across an orifice for the purpose of bypassing excess pump flow. The flow control orifice establishes pressure signals proportional to pump flow to the steering mechanism. The pressure signals are operative on the valve spool to control the bypassing of excess pump flow. A spring loaded metering rod disposed in the flow control orifice increases the effective area of the orifice when pressure demand at the steering mechanism increases thereby increasing the fluid flow to the steering mechanism while simultaneously decreasing the bypass flow.

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 flow volume control device for use in a power steering system, which comprises: a casing having an inlet port, a reflux port and a delivery port; a fluid passage formed in the casing in communication with the inlet, reflux and delivery ports; fixed orifice means provided in the fluid passage to restrict the flow or pressurized fluid from the inlet port to the reflux and delivery ports; and throttle means provided in the fluid passage between the fixed orifice means and delivery port.

Abstract: In a vane pump of the type comprising a rotor including radially slidable vanes, a cam ring accommodating the rotor, a front body and a rear body secured to both sides of the cam ring for defining pump chambers together with the cam ring, there is provided an intermediate body having an inner opening for accommodating the cam ring. The intermediate body is disposed between the front and rear bodies, and a portion of the inner opening is bulged outwardly to form a fluid passage for conveying operating fluid from the body to the rear.

Abstract: A hydraulic system comprising a fixed displacement pump driven by a prime mover operable at variable speeds and a flow control valve operable to return a portion of the hydralic fluid from the outlet of the pump to the inlet of the pump and draw fluid from a reservoir to replenish the fluid at the inlet when the pump is operated at higher speeds. An auxiliary passage extends from the reservoir and communicates with the inlet of the pump upstream from the system flow drawn from the reservoir by the opening of the flow control valve and normally isolated during low speed operation from the bypass flow by the flow control valve thereby providing auxiliary flow to the inlet at lower speeds.

Abstract: In a scroll compressor, means for maintaining the motion of an orbiting plate in fixed angular relationship to a stationary plate and for modulating the capacity of the compressor. The orbiting and stationary plates include intermeshed wrap elements of similar spiral shape about an axis. A coupling ring is slideably disposed between the plates and sealingly encloses the wrap elements. Four slots are provided in the coupling ring, aligned at right angles to each other and spaced apart around its inner circumference. Three segments, extending outward from the wrap elements, sealingly engage these slots. The fourth slot is engaged by a sliding key attached to one of the plates. The segments separate a first and a second fluid inlet and cooperate with the slots in the coupling ring to constrain the orbiting plate's motion in fixed angular relationship to the stationary plate.

Abstract: A constant displacement pump and an associated flow control mechanism are disclosed. The flow control mechanism includes a variable orifice, i.e., a pintle and valve seat in the outlet from the pump. The pressure drop across the variable orifice controls the position of a bypass valve. The position of the pintle member relative to the valve seat is controlled by fluid pressure acting on one end of the pintle member. The fluid pressure acting on the one end of the pintle member may be infinitely varied so that the position of the pintle member with respect to the valve seat may be infinitely varied. Fluid pressure acting on the one end of the pintle member is controlled by an electrical solenoid which infinitely positions a pilot member relative to a fluid pressure passage joining the opposite ends of the pintle member.

Abstract: A compressor comprises a main compressor body of compressing air, an unloader valve device provided at the suction side of the main compressor body, a bleeding pipe provided between the ejection side of the main compressor body and the unloader valve device, and a controlling valve mechanism provided inside the bleeding pipe. The controlling valve mechanism opens by detecting the fluid pressure at the ejection side of the main compressor body. Further, the unloader valve device has a check valve which opens upon-no-load operation and stopping of the operation of the main compressor body, a main valve which opens due to the air released through the bleeding pipe when the controlling valve mechanism opens, a bleeding passage for releasing the released air supplied to the suction side of the check valve, and a relief passage which communicates when the main valve opens, to release the released air to the suction side of the main compressor body.

Abstract: A rotary pump and flow control valve assembly (73) are disclosed. The pump includes a pumping element (17) defining fluid pockets (31), a discharge port (59) and a discharge fluid path (57). The flow control valve assembly is disposed in a valve bore (71) and includes a valve spool (83) having a spool land (105) disposed between the discharge path and a bypass bore (81). The spool land includes a cylindrical wall portion (109) and an annular wall portion (111) extending from the spool to the cylindrical wall portion. The wall portions define an annular fluid chamber (115) in communication with the discharge path. The wall portions are relatively thin such that the cylindrical wall portion expands radially when the annular fluid chamber communicates with fluid at relatively higher fluid pressure. The result is a reduction in the normal clearance between the cylindrical wall portion and the valve bore, reducing leakage past the spool land.

Abstract: A flow volume control device for a power assisted steering device having a main control valve device, whose main valve spool is movable to establish the communication of an inlet passage with a bypass passage when the flow rate of pressurized fluid supplied from an engine-driven pump to the steering device through the inlet passage and first and second throttle passages disposed in parallel relation exceeds a predetermined value. For safe driving at a high speed, an auxiliary control valve device is further provided, whose auxiliary valve spool is moved to close the second throttle passage when high-speed driving causes pressurized fluid from the pump to increase in volume, to thereby bring about a predetermined pressure drop across said inlet passage.

Abstract: A positive displacement pump system has two delivery passages communicating under the control of a valve with a main discharge passage and/or an overspill duct. The valve is constituted by a valve member slidably mounted in a valve bore and the valve member has lands and intermediate recesses controlling communication between the delivery passages and the overspill duct. The pressures upstream and downstream of a discharge orifice in the discharge passage are applied to the valve member in opposition to each other, increase of the pressure drop tending to move the valve member to increase the amount of fluid passed to the overspill duct. To overcome the known tendency for a valve member to be subjected by the hydraulic forces to a large closing force when the valve is open to only a small extent, the valve is designed to provide for a relatively large opening force at least when the valve is commencing to open.

Abstract: A valve system in a power steering system is disclosed. It includes a spool valve which is slidably located in a valve bore for by-passing an excess fluid at high vehicular speed in response to the pressure differential across an orifice. A control rod is slidably located in the spool valve and has at the end a metering portion for maintaining a limited flow volume when the spool valve is moved to close a by-pass port with the increase of a working pressure in the power steering system.

Abstract: A power steering pump having a cam with an internal cam surface defining pumping arcs, a rotor in said cam, pumping elements preferably in the form of slippers carried by the periphery of the rotor in sliding engagement with the pumping arcs, flow control valve means having a movable valve element responsive to both static pressure and velocity pressure of the displaced fluid on the high pressure side of the pump wherein provision is made for decreasing the volume of fluid delivered by the pump at high pressure upon an increase in the speed of the rotor, and means for equalizing the pressure between the volume of fluid between two adjacent pumping elements located at a high pressure outlet port and a corresponding volume of fluid between two other adjacent slippers located at a low pressure inlet port as the pumping elements pass through their respective pump cycles.

Abstract: A positive displacement pump system provides first and second delivery 11, 12 passages of which the first passage 11 communicates with a main discharge passage 15 containing a discharge orifice 17. The second delivery passage 12 opens to a valve bore and is in permanently open communication with the first delivery passage through an axial passage 29 in a valve member 20 slidably mounted in the valve bore. Lifting of the valve member with increasing pressure drop across the orifice 17 places the first delivery passage in communication with an overspill port 14. The pressure at the upstream and downstream sides of the orifice are applied against the lower end and the upper end 28 of the valve member so that the valve operates to maintain the pressure difference constant. The pressure difference between passage 29 and that applied against the upper end 28 of the valve member is therefore also substantially constant, so that leakage from passage 29 past the upper end 28 is constant.

Abstract: A rotary hydraulic device in which a pair of delivery ports of a vane pump communicate with independently separated delivery chambers, respectively, and the communication between one of the delivery chamber and a hydraulic machine is shut off after the flow rate of delivery fluid from the delivery port exceeds a certain level with the increase in the speed of rotation of the pump. The excess fluid from the delivery port is returned to the tank side which causes the decrease of the supply flow rate in the zone of high speed rotation of the pump and also the reduction of power consumption so that the rotary hydraulic device of the invention is especially suitable for the power steering devices of vehicles.

Abstract: Fluid flow regulating systems involving systems for controlling the motor speed of fluid pumping devices are disclosed. The speed control systems involve use of a velocity head force sensor that movably responds to the velocity head forces of an air stream delivered by the pumping device, and these movements in the positions assumed by the force sensor are detected and used to control the power delivered to the motor. Temperature change detectors are used in most embodiments to modify the force sensor movements so as to introduce temperature change factors as well as velocity head force change factors into the control of the power circuitry. Force sensor of the pivotal vane, bendable vane and airfoil types are shown, and temperature sensors of the bimetallic and expandable fluid types are also used.

Abstract: A flow control valve has a slidable valve member and a variable orifice structure. The valve member slides in response to a pressure differential, created by fluid flow through the variable orifice, to bypass fluid in a positive displacement pump. The variable orifice is a self-contained unit including a longitudinally movable pin having a variable cross section disposed in an aperture. The pin position in the aperture controls the size of the orifice and thereore imposes a flow restriction which creates the pressure differential. The flow control valve is useful with power steering hydraulic pumps and systems where it is desirable to reduce the amount of hydraulic fluid which is delivered to the steering mechanism when the pump input speed exceeds a predetermined value.

Abstract: A method and apparatus for the diversion of fluid flow at reduced pressure out of a high pressure fluid delivery system when the discharge of the system is closed. A bypass valve having a movable piston oriented transverse to the flow direction and a slidable seal oriented parallel to the flow direction is located between the system pump and discharge. The movable piston has two working surfaces of different areas which define planes parallel to the flow direction so that the working surfaces and therewith the piston are generally responsive only to static fluid pressure. The slidable seal is responsive to dynamic fluid pressure so that when the discharge is closed and the dynamic fluid pressure thereby reduced, the seal moves to interrupt fluid communication between the two working surfaces of the piston.

Abstract: A transfer valve for a gas turbine fuel system by which to transfer fuel flow from the main control to the back-up control without allowing fuel flow transients in excess of the mismatch between the two controls.