Abstract: Illustrative embodiments of diaphragm pumps including a sensor mount are disclosed. In one illustrative embodiment, a diaphragm pump may include a shaft disposed within a pump housing and coupled to at least one diaphragm, a mount removably attached to the pump housing and having a sensor receptacle, and a proximity sensor received in the sensor receptacle of the mount such that a sensing end of the proximity sensor is flush with an end of the sensor receptacle nearest the shaft.

Abstract: One or more techniques and/or systems are disclosed for increasing compressed air efficiency in a pump that utilizes an air efficiency device in order to optimize the amount of a compressed air in the pump. The air efficiency device may allow for controlling the operation of the air operated diaphragm pump by reducing the flow of compressed air supplied to the pump as the pump moves between first and second diaphragm positions. A sensor may be used to monitor velocity of the diaphragm assemblies. In turn, full position feedback is possible so that the pump self-adjusts to determine the optimum, or close to optimum, turndown point of the diaphragm assemblies. As such, air savings are achieved by minimizing the amount of required compressed air.

Abstract: A high-pressure fuel injection valve may include a control valve having an actuator, a high-pressure fuel connection and a low-pressure fuel connection. A control plunger and nozzle needle are aligned longitudinally in the valve stem and the valve tip. Together with the control plunger, the receiving chamber of the control plunger forms a closing control chamber delimited by the upper control plunger surface, and an opening control chamber delimited by the lower control plunger surface. Each control chamber is hydraulically connected via a feed throttle to the high-pressure fuel connection and via a return throttle to the low-pressure fuel connection. The control valve opens and closes the fuel return between the return throttles and the low-pressure fuel connection depending on the operation. The flow values of the feed throttles and of the return throttles are selected such that the high-pressure fuel injection valve opens and closes based on actuation of the control valve.

Abstract: Methods, devices and systems capable of performing a hot restart of a compressor driven by a turbine are provided. The turbine has a high speed shaft and a low speed shaft connected to the compressor. A base slow roll speed at which a speed of the low speed shaft is in a slow roll range is maintained at the high speed shaft for a predetermined time. Then, when a vibration amplitude of the compressor is larger than a vibration limit, the maintaining is repeated. Otherwise, a set speed of the high speed shaft is increased, until a current speed of the low speed shaft reaches a minimum operating speed. If, while increasing the set speed, the vibration amplitude becomes larger than the vibration limit, the maintaining is repeated.

Abstract: One or more techniques and/or systems are disclosed for increasing compressed air efficiency in a pump that utilizes an air efficiency device in order to optimize the amount of a compressed air in the pump. The air efficiency device may allow for controlling the operation of the air operated diaphragm pump by reducing the flow of compressed air supplied to the pump as the pump moves between first and second diaphragm positions. A sensor may be used to monitor velocity of the diaphragm assemblies. In turn, full position feedback is possible so that the pump self-adjusts to determine the optimum, or close to optimum, turndown point of the diaphragm assemblies. As such, air savings are achieved by minimizing the amount of required compressed air.

Abstract: Systems and methods of the invention relate to monitoring a change in a rotational speed of a crankshaft to identify a failure related to a crankcase breather valve. A reciprocating compressor can include a detection component that is configured to track a rotational speed of a crankshaft of a compressor to identify a change in rotational speed. In an embodiment, the rotational speed can be monitored while unloaded and/or below approximiately 800 Revolutions Per Minute (RPM). Based on a change in a rotational speed of the crankshaft, a controller can be configured to communicate an alert which corresponds to a failure related to the crankcase breather valve.

Abstract: One or more techniques and/or systems are disclosed for increasing compressed air efficiency in a pump utilizes an air efficiency device in order to optimize the amount of a compressed air in a pump. The air efficiency device may allow for controlling the operation of the air operated diaphragm pump by reducing the flow of compressed air supplied to the pump as the pump moves between first and second diaphragm positions. A sensor may be used to monitor velocity of the diaphragm assemblies. In turn, full position feedback is possible so that the pump self-adjusts to determine the optimum, or close to optimum, turndown point of the diaphragm assemblies. As such, air savings is achieved by minimizing the amount of required compressed air.

Abstract: A feedback control loop for a high pressure pump modifies the accumulator velocity and pressure during solvent transfer. The accumulator velocity is adjusted to maintain the system pressure equal to the expected pressure to thereby eliminate the effect of the flow deficit created by a thermal effect.

Abstract: A hybrid vehicle includes a hybrid module, a transmission and a torque converter. The lubrication system associated with the torque converter includes an oil sump within the torque converter housing which is intended to be managed as a “dry” sump oil lubrication system. There is an oil pump in communication with the sump in order to manage the sump oil level. By monitoring an operational parameter of the oil pump motor (pressure, torque, or current) oil aeration can be detected.

Abstract: A control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system. By varying an opening of an antisurge or recycle valve, a shaft power used by the compressor in the compressor-expander set may be varied, thereby varying the rotational speed of the compressor-expander set to move it away from its critical speed zone. Additionally, a feedforward signal may be provided by a compressor-expander set control system to cause an antisurge valve for a recycle compressor to open upon a trip or shutdown of one compressor-expander set.

Abstract: A control method and apparatus for critical rotational speed avoidance in a compressor-expander set in a gas refrigeration system. By varying an opening of an antisurge or recycle valve, a shaft power used by the compressor in the compressor-expander set may be varied, thereby varying the rotational speed of the compressor-expander set to move it away from its critical speed zone. Additionally, a feedforward signal may be provided by a compressor-expander set control system to cause an antisurge valve for a recycle compressor to open upon a trip or shutdown of one compressor-expander set.

Abstract: A stability valve assembly includes a centrifugal pump and a valve downstream of the centrifugal pump. The valve includes a valve member that is movable along a valve axis within a valve body to control a fluid flow from the centrifugal pump. The valve member has a first orifice connecting a valve input to a valve chamber, and has at least one second orifice connecting a valve outlet to the valve chamber. A reference pressure upstream of the centrifugal pump applies pressure to a stepped portion of the valve member such that an amount of negative feedback provided by the valve assembly is proportional to a rotational speed of the centrifugal pump.

Abstract: Methods, devices and systems capable of performing a hot restart of a compressor driven by a turbine are provided. The turbine has a high speed shaft and a low speed shaft connected to the compressor. A base slow roll speed at which a speed of the low speed shaft is in a slow roll range is maintained at the high speed shaft for a predetermined time. Then, when a vibration amplitude of the compressor is larger than a vibration limit, the maintaining is repeated. Otherwise, a set speed of the high speed shaft is increased, until a current speed of the low speed shaft reaches a minimum operating speed. If, while increasing the set speed, the vibration amplitude becomes larger than the vibration limit, the maintaining is repeated.

Abstract: A positive displacement pump is provided. The pump includes a housing, and first and second meshed rotors rotatably disposed in the housing and arranged to transform relatively low-pressure inlet port air into relatively high-pressure outlet port air. The pump additionally includes first and second meshed timing gears fixed relative to the first and second rotors, respectively, for preventing contact between the first and second rotors, and sufficiently enclosed to generate a flow of lubricating fluid. Furthermore, the blower includes an input drive adapted to be rotatably driven at speeds proportional to speeds of an internal combustion engine and arranged to drive the first and second timing gears.

Abstract: A stability valve assembly includes a centrifugal pump and a valve downstream of the centrifugal pump. The valve includes a valve member that is movable along a valve axis within a valve body to control a fluid flow from the centrifugal pump. The valve member has a first orifice connecting a valve input to a valve chamber, and has at least one second orifice connecting a valve outlet to the valve chamber. A reference pressure upstream of the centrifugal pump applies pressure to a stepped portion of the valve member such that an amount of negative feedback provided by the valve assembly is proportional to a rotational speed of the centrifugal pump.

Abstract: A variable water pump control apparatus, may include a detecting portion detecting engine speed, operation of an idle stop and go system (ISG), coolant temperature, operation of a blower, and outside temperature, a variable water pump selectively circulating a coolant through an engine, and a control portion controlling the variable water pump according to the detected information including operating conditions and outside environmental factors, and a variable water pump control method may include detecting a driving condition and an environmental condition of a vehicle, and engaging or releasing a clutch of a variable water pump according to a detected condition so as to selectively circulate a coolant.

Abstract: A hybrid electrical power assist system (EPAS) for an automotive vehicle that utilizes the advantages of a conventional EPAS system to provide power assist based upon several distinct sensor inputs, in a heavy duty vehicle that requires significantly more assistance forces than a conventional EPAS can provide. The hybrid system utilizes a hydraulic amplifier that is connected to receive the torque output from an EPAS motor actuator and responsively provide a fluid under differential pressure through a pair of high pressure lines to a steering piston.

Abstract: A method for increasing compressed air efficiency in a pump utilizes an air efficiency device in order to optimize the amount of a compressed air in a pump. The air efficiency device may allow for controlling the operation of the air operated diaphragm pump by reducing the flow of compressed air supplied to the pump as the pump moves between first and second diaphragm positions. A sensor may be used to monitor velocity of the diaphragm assemblies. In turn, full position feedback is possible so that the pump self adjusts to determine the optimum, or close to optimum, turndown point of the diaphragm assemblies. As such, air savings is achieved by minimizing the amount of required compressed air.

Abstract: A vane pump of the intravane type for pumping hydraulic fluid, wherein each vane of the pump has two intravanes and that pressurized oil is provided to one or both intravane regions when the vane is in a rise region of the pump. The pump is operated such that the pressurized oil is provided to both undervane regions when the pump is running at low speed but the pressurized oil is provided to only one of the undervane regions when of the pump is running at high speed.

Abstract: A feedback control loop for a high pressure pump modifies the accumulator velocity and pressure during solvent transfer. The accumulator velocity is adjusted to maintain the system pressure equal to the expected pressure to thereby eliminate the effect of the flow deficit created by a thermal effect.

Abstract: A centrifugal fluid pump assembly includes a body section and a control mechanism 6. The body section includes a housing, an impeller rotatable within the housing, and a motor for rotating the impeller. The pump assembly includes a motor current flow rate-related data storage section for storing, for a plurality of different predetermined viscosities, predetermined viscosity-related flow rate data formed from a plurality of motor current flow rate relation data at a plurality of different impeller rotational speeds at predetermined fluid viscosity, a fluid measurement data inputting section, an impeller rotational speed measurement function, a motor current measurement function, and a flow rate calculating section 58 for using a fluid viscosity value, an impeller rotational speed value, a measured motor current and data stored in the motor current flow rate-related data storage section to calculate a fluid flow rate.

Abstract: This invention relates to a wind mill which is designed to convert rotational energy to mechanical energy to drive one or more pistons to raise a liquid such as water to an elevated location if necessary at a positive pressure. In addition, the present invention may be adapted to pressurize a medium, such as a gas, for storage in a reservoir.

Abstract: An exemplary oil delivery system comprises a dual pump system configured for reducing the buildup of pressure by unloading one or both pumps, thus reducing the buildup of heat within the hydraulic system. The dual pump system is configured for delivering oil in combination to a single hydraulic system or to two completely separate hydraulic systems. In addition, the oil delivery system can also be configured to unload one or both of the pumping sections at a pre-determined speed to again limit the flow to any existing open centered hydraulic system. As a result, the oil delivery system recirculates oil back to the reservoir and/or the inlet to the pump in the absence of a buildup of pressure, and thus an absence in the buildup of heat to conserve energy.

Abstract: Air-demand-controlled compressor arrangement, particularly for commercial vehicles, includes a motor unit for generating a rotating movement which, by way of an interposed rotational-speed-transmitting transmission unit, drives a compressor unit for generating compressed air from ambient air. A control unit triggers the generating of compressed air in the case of a compressed-air demand. The transmission unit is constructed in the manner of a transmission whose rotational speed can be varied, and the control unit interacts with the transmission unit in order to adapt the rotational speed of the transmission unit corresponding to the compressed-air demand.

Abstract: A method and a pump apparatus are provided for the generation of an adjustable, substantially constant volume flow of a fluid by means of a pump apparatus, wherein the fluid (5) is forwarded by the pump apparatus (1) from a reservoir (2) into a flow connection (4). A rotary pump (1) is used as the pump apparatus and the rotary pump (1) is operated at an efficiency which is less than half the maximum efficiency (&eegr;max) of the rotary pump (1).

Abstract: First and second fluid pressure chambers are formed in both sides of a movement direction of a cam ring swingably placed within a pump body. A spool of a control valve is moved due to a pressure difference between the front and back of a metering orifice. Fluid pressures of the fluid pressure chambers are controlled. The cam ring is swung. Further, a solenoid for giving thrust in an axial direction thereof to the spool of the control valve and electronic control device for controlling driving of the solenoid are provided. The electronic control device has a steering sensor and determines a steering direction based on a signal from the steering sensor and also calculates a steering speed to the steering direction and controls a driving current of the solenoid in response to this steering speed and changes a discharge flow rate of a pump.

Abstract: A control system is provided for load sharing between a plurality of compressors. The control system determines the actual coefficients of export flow for the compressors, compares the actual coefficients of export flow with a common or individual coefficients of export flow setpoints generated by one or more central controllers, and then generates control signals for adjusting the operating points of the compressors in order to load balance the compressors.

Abstract: A control system for a vacuum pump used for removing liquid from a suction washer of a pulp mill includes a pump with adjustable rotation speed and means for defining the operating point of the vacuum pump and a control/central unit wherein the performance chart of the vacuum pump is recorded and wherein the defining data of the vacuum pump operating point is fed. The control system further includes a resistance function on the suction side of the vacuum pump which depicts the suction resistance formed of at least the suction object in the suction side. The resistance function is determined by changing the rotational speed of the vacuum pump and recording the operating points in the control/central unit at various rotational speeds.

Abstract: A fluid pump is provided that produces an outflow of fluid that is not proportional to the speed of the input drive. Thus, the fluid pump can be tuned to provide a substantially constant outflow of fluid irrespective of the speed of the input drive. The fluid pump also provides fluid outflow when the rotational direction of the input drive is reversed.

Abstract: The present technique utilizes already existing components within a variable speed drive to provide harmonic filtering characteristics. Particularly, the present technique integrates transformers and inductors to provide a filter within the variable speed drive. Further, the present technique may also utilize a sine wave filter to provide additional filtering of unwanted frequencies.

Abstract: First and second fluid pressure chambers are formed in both sides of a movement direction of a cam ring swingably placed within a pump body. A spool of a control valve is moved due to a pressure difference between the front and back of a metering orifice. Fluid pressures of the fluid pressure chambers are controlled. The cam ring is swung. Further, a solenoid for giving thrust in an axial direction thereof to the spool of the control valve and electronic control device for controlling driving of the solenoid are provided. The electronic control device has a steering sensor and determines a steering direction based on a signal from the steering sensor and also calculates a steering speed to the steering direction and controls a driving current of the solenoid in response to this steering speed and changes a discharge flow rate of a pump.

Abstract: An auxiliary solenoid controlled variable displacement power steering pump, hydraulic systems incorporating same, and method for improving the efficiency of variable displacement power steering pumps. In one embodiment, a rotor is arranged within a pump body, and a cam fitted on an outer periphery of the rotor and movably arranged within the pump body to form a variable volume pump chamber. The cam is biased towards a position within the pump body to create maximum displacement. A mechanism is provided for forcing the cam into a position of fixed minimum or reduced displacement under certain conditions, such as low engine speed and power steering demand. In a preferred embodiment, the mechanism comprises a solenoid driven connecting rod that is operatively connected to the cam. Activation of the solenoid forces the cam to a position of fixed minimum or reduced displacement.

Abstract: Fluid pump control modes in a medical perfusion system include a Back Off Response Mode, a Flow Servo Mode, a Pressure Servo Mode, and a Master-Slave Servo Mode. In the Back Off Response Mode, pump's speed is decremented to a new speed when an excessive flow rate or pressure condition is detected. The new speed is maintained until an additional decrement is required or until the Back Off Response Mode is exited. In the Flow Servo Mode, a pump's speed is controlled to maintain a fluid flow rate indicated by a user as a setpoint. In the Pressure Servo Mode, a pump's speed is controlled to maintain a pressure indicated by the user as a setpoint. In the Master-Slave Servo Mode, a slave pump receives an indication of a master pump's speed, and the slave pump speed is controlled to maintain a specified percentage of the master pump's speed.

Abstract: A fluid delivery device, in particular for the delivery of combustion air to a heating burner of a motor vehicle or for the delivery of heating medium, preferably heating air, through a heating medium duct system of a motor vehicle, comprises a delivery member which can be driven to rotate by a drive, a rotary state monitoring arrangement for monitoring the rotary state of the delivery member, and also an operating state sensing arrangement for determining the operating state of a system to be supplied with fluid by the fluid delivery device, based on the monitoring result of the rotary state monitoring arrangement.

Abstract: The present invention provides a vacuum pump allowing process pressure control with high responsiveness and miniaturization and cost reduction of the overall apparatus, as well as reduction of the running cost. A second pump mechanism portion is equipped on the way of an exhaust passage communicating an exhaust side out of a first pump mechanism portion with a gas outlet. The second pump mechanism portion is constructed to be capable of changing the pump speed of rotation independently of the first pump mechanism portion. When the pump speed of rotation of the second pump mechanism portion is changed, the pressure of the exhaust side out (backing pressure) of the first pump mechanism portion changes. Therefore, efficiency of gas suction from a gas inlet to the first pump mechanism portion side is increased or decreased, and the pressure in a process chamber is changed.

Abstract: An exemplary oil delivery system comprises a dual pump system configured for reducing the buildup of pressure by unloading one or both pumps, thus reducing the buildup of heat within the hydraulic system. The dual pump system is configured for delivering oil in combination to a single hydraulic system or to two completely separate hydraulic systems. In addition, the oil delivery system can also be configured to unload one or both of the pumping sections at a pre-determined speed to again limit the flow to any existing open centered hydraulic system. As a result, the oil delivery system recirculates oil back to the reservoir and/or the inlet to the pump in the absence of a buildup of pressure, and thus an absence in the buildup of heat to conserve energy.

Abstract: A semiconductor device manufacturing apparatus. The semiconductor device manufacturing apparatus includes: a tank having an inlet and an outlet, for storing a chemical solution; a pump interposed between the inlet and outlet of the tank, for circulating the chemical solution contained in the tank; a filter interposed between the pump and the inlet of the tank; at least one main body connected to an outlet of the filter; a pumping cycle sensor for changing the pumping operation of the pump into a pulse signal; and a controller for measuring the cycle time of the pulse signals generated by the pumping cycle sensor to determine the level of deterioration of the filter.

Abstract: A method and apparatus to convert the torque of a drive shaft into reciprocating energy to drive and pull a piston utilizing a nodal rotator attached to the drive shaft, or alternatively to convert reciprocating energy into torque, said rotator having compression and repositioning means associated with cam followers which drive and pull opposed pistons and cylinders in air compressors, internal combustion engines, and other technology.

Abstract: A central impeller is sandwiched between fixed walls and is driven through a circular path of small radius, but prevented from rotating by a ring-shaped shutter or slider which surrounds and guides it. The shape of the impeller and slider are such that displacement chambers are formed between them, which expand and contract as the impeller follows a circular path and imparts a reciprocating motion to the slider. The two fixed walls contain suction and discharge ports which are covered and uncovered by the impeller and the slider as they perform their motions.

Abstract: A rolling-piston expander has a hermetic casing 7 provided with a suction pipe 3 and a discharge pipe 5, a cylinder 13 disposed in the casing, a roller 31 eccentrically rotated in the cylinder, an expansion chamber 39 defined by the roller and communicating with a suction port 47 and a discharge port 55, a shaft 19 for supporting the roller so that the roller may eccentrically rotate, a suction timing controller 51 consisting of the ports 47 and 51, for controlling the timing of the supply of gas into the expansion chamber, and a bypass for supplying high-pressure gas into the expansion chamber when the suction timing is off.

Abstract: A compressor with a hypotrochoidal design is constructed in such fashion that its delivery can be varied in ways other than by the drive rpm alone. A controlling edge of an inlet opening that determines the beginning of compression has a variable angular position for this purpose.

Abstract: An actuator for moving a solenoid armature to control fuel in response to a control current is built into a fuel pump, with trapped air in and around the actuator preventing contamination of the actuator by ferromagnetic particles in the liquid fuel from the fuel pump.

Abstract: A fluid rotating apparatus of a positive displacement pump includes a plurality of rotors accommodated in a housing, a bearing for rotatably supporting the rotors, a suction port and a discharge port formed in the housing, a suction chamber and a discharge chamber in the housing respectively communicating with the suction port and the discharge port, a plurality of motors for individually rotating the rotors, and a detecting device for detecting rotating angles and rotating numbers of the motors. In the apparatus, a fluid is sucked and discharged due to capacity change of a space defined by the rotors and the housing through synchronous control of the rotation of the plurality of motors by a signal from the detecting device. The housing has a communicating path with a flow control device to make an upstream side communicate with a downstream side of the apparatus when the rotational numbers of the rotors are less than a predetermined value.

Abstract: A reverse osmosis water purification system that incorporates a high torque low speed motor to drive a pump, such that the pump can continuously pump water from a source of water to an osmotic membrane The system may have a reservoir to store the purified water as it is pumped through the osmotic filter. The system can also have a transformer and rectifier to convert and rectify an alternating electrical power source to 24 volt DC power for the motor. The transformer having a higher impedance than the motor such that the transformer acts as a current limiter in the event the motor stalls. The pump has an internal pressure relief valve Operatively connected to the inlet of the pump housing. The relief valve opens when the output pressure of the diaphragm piston reaches a predetermined valve. The relief valve allows the high pressure water to flow back into the housing inlet creating a flow loop from the inlet back to the water source.

Abstract: A pump control interface for use in a diaphragm pump including at least one diaphragm adapted to move between a suction stroke and a discharge stroke during operation of the pump. A diaphragm follower is connected for movement with the diaphragm during operation of the pump. A sensor mechanism is provided for sensing at least the position and rate of movement of the diaphragm by sensing the position and rate of movement of the diaphragm follower. In one embodiment, the control interface is provided as a rod interconnecting two diaphragms of a dual diaphragm pump for synchronous movement. A plurality of conductive targets are disposed on the rod, and a proximity switch is mounted adjacent to the rod, in order to produce pulsed output signals when in proximity with the conductive targets.

Abstract: The invention describes an arrangement for optimum flooding of high speed vacuum pumps. The actuation of the flood valve (6) is controlled by the forces, which, among other things, are exerted upon the rotor by the flooding process. These forces are determined and used to actuate a flood valve controlling entry of the flooding gas. Such forces can be measured in active magnetically supported rotors by masuring the currents in the magnetic bearings (10 and 12). In case of hybrid bearing systems and purely mechanical bearing systems, force measurement is possible indirectly by means of measuring the distance or spacing between the rotor and the stator, or, alternatively, also by means of force sensors.

Abstract: A system for controlling vehicle passenger compartment comfort. An electronic controller receives input from: (i) a thermistor array sensing blower plenum discharge temperature, (ii) a user movable Level Select Control (iii) a potentiometer sensing the position of a servo driven heater core water valve, (iv) an engine rpm tachometer generator and (v) a blower speed signal. The controller employs proportional-integral-derivative (PID) strategy in a microprocessor to generate a control signal for operating the heater core valve servo motor to maintain the plenum discharge air at a constant temperature irrespective of wide swings in engine rpm/water pump speed or user selector changes in blower speed.

Abstract: An automatic control system for regulating the temperature of blower air discharged over a heater core to a vehicle passenger compartment. A thermistor is disposed to sense discharge air adjacent the heater core and provide a temperature signal. An electrical indication is provided of the condition of a servomotor driven valve controlling water flow to the heater core. An electrical reference signal is provided indicative of a user selected relative change of flow discharge air temperature. A signal is provided indicating the speed of the water pump circulating liquid to the heater core. The signals are summed and the valve sums driven until the sum is zero and the valve modulated to maintain the sum at zero for regulating blower air discharge temperature constant.

Abstract: A method of and an apparatus for effecting volume control suitable for use with a compressor for compressing a compressible fluid, such as a refrigerant of the refrigeration cycle, wherein a suction fluid is forcedly closed while a suction step is being performed and the fluid drawn up to then by suction into each working chamber is subjected to adiabatic expansion during the rest of the suction stroke. The fluid in the working chamber subjected to adiabatic expansion is then subjected to adiabatic compression in initial stages of a compression stroke following the suction stroke only for a period corresponding to the period of the adiabatic expansion. An on-off control valve is mounted in a fluid suction passage and operative to be brought, when it is necessary to effect volume control, to a closed position while the suction stroke is being performed, to thereby interrupt the flow of the fluid through the fluid suction passage to the working chamber.

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.