Abstract: A gear pump which comprises a casing provided with an inlet port communicating with an intake chamber, and a delivering port communicating with a delivery chamber. A drive gear is mounted in meshing engagement with a driven gear, each gear being placed in a corresponding bore in the casing, the gears being placed in the flow path between the intake chamber and the delivering chamber.One of the gears contains a central bore with passages which connect the bore to the gaps between adjacent teeth of the gear. A spool is slidable in the central bore for controlling fluid communication through the passages and the movements of the spool are controlled by the pressure difference between the fluid pressure in the delivery chamber and an operating pressure in such a way that the spool is held in a closure position in which the communication through the passages remains blocked as long as the delivery of the pump remains below a given level corresponding to a predetermined pressure difference.

Abstract: A pump unit comprises a housing defining a pumping chamber, a fluid inlet and a fluid outlet communicate with the pumping chamber. A pair of cooperating gear members are located in the pumping chamber to pump fluid from the inlet to the outlet. A pintle member and a valve seat are located in the outlet and an electric motor is provided for moving the pintle member relative to the valve seat. The pintle member and valve seat comprise a variable orifice. The pump unit also includes a bypass valve for bypassing fluid from the outlet to the inlet to thereby control flow of fluid to the system. The amount of fluid which is bypassed is controlled by a spool valve member which is movable in response to forces acting thereon. The spool valve member is acted upon by the pressure drop across the variable orifice. Thus, by adjusting the size of the orifice, the position of the spool valve can be controlled and as a result the amount of flow to the system can be controlled.

Abstract: The present invention discloses a power-steering pump which may reduce in a very stable manner the flow rate of the hydraulic liquid under pressure to be delivered to a power steering system with increase of the rotational speed of an engine beyond an idling speed and which may easily change the above rate reduction or attenuation characteristic depending upon the types of the automotive vehicles and power steering systems thereof. A flow-control valve which is disposed in parallel with the axis of a pump mechanism is provided with a variable-area orifice which determines the flow rate attenuation characteristic and which is defined by an orifice groove cut through a flange of a partition wall member and an enlarged-diameter portion at the free end of a control rod extended through the partition wall member from the front end of a control spool of the flow-control valve.

Abstract: A pump comprises a housing having an inlet and an outlet. The housing defines a pumping chamber and pumping means is located in the chamber and is operable to pump fluid from the inlet to the outlet. The pumping means includes pumping elements which define a series of pumping pockets which expand and contract to effect pumping of fluid. A cheek plate having one axial side adjacent to and facing the pumping means is supported in the housing. The cheek plate has a sealing position blocking fluid communication between the pumping pockets and is movable therefrom to enable fluid to flow directly between the pockets. The housing defines a cavity on the other axial side of the cheek plate. A fluid passage directs a flow of fluid from the pumping means into the cavity for urging said cheek plate into sealing position. A seal is provided between the cheek plate and the housing blocking flow into the cavity. An orifice is located in the pump outlet.

Abstract: A motor vehicle servo steering system control for flow rate to the hydraulic steering cylinder mechanism utilizes a flow regulating bypass valve between the inlet and outlet of the system pump. A throttle bore device in the pump outlet is adjustable as to bore position to effect a variable operating pressure differential on the flow regulating valve bypass of the pump. The purpose of the arrangement is to effect as constant as possible a rate of flow to the steering servo cylinder mechanism at any given speed but with lowering of rate of flow when pump speed is increasing with engine speed. Accordingly, the invention provides a generally uniformly varying decrease in the amount of steering assist which a vehicle driver receives with increase in vehicle speed so as to convey a safer sense of road reaction at high speeds than would otherwise occur.

Abstract: The invention relates to a supply apparatus for two receiving means having a pressure summation device.A relief valve with a double control system is provided on a pipe shunted to the delivery pipe of the pump and has two control connections, a rod connecting the discharge member of the pressure summation device to the first of the said connections and a control pipe connecting that portion of the discharge pipe located between the connection of the latter to the delivery pipe and the relief valve to the second of the said connections.The invention is applicable to the realization of a supply apparatus with a pressure transfer system.BACKGROUND OF INVENTIONThe present invention relates to an apparatus for supplying pressurized fluid to two receiving means with pressure transfer by means of a double control valve.Apparatuses for supplying two receiving means equipped with a pressure transfer system are already known. Such an apparatus is for example described in French Publication No. 2,218,007 of Sept.

Abstract: A relief valve for limiting the pressure of the output of a feed pump being furnished to a main hydraulic pump is provided not only with a bore through the valve disk leading to a chamber at the rear of the guide piston for counteracting, as relief valving continues, the force of the spring tending to keep the valve closed, but also a pressure piston, in the form of an annular flange on the guide piston, subdividing an outer cylindrical space into two chambers respectively connected to a constriction in a hydraulic conduit, so that the amount of flow through the constriction will additionally modify the limit pressure at which relief valving takes place. The device is used to reduce the limit pressure when the feed pump provides excessive oil feed to the main pump.

Abstract: An automatic control system for high pressure blower applications prevents surging under variable supply flow rate requirements and achieves maximum efficiency of operation. The supply flow rate establishes the set point of a proportional plus reset controller, the latter receiving a feedback signal corresponding to the static discharge pressure of the supply blower and responding thereto for controlling the output of the supply blower. A return blower is controlled either through a characterizer relay in proportion to the control of the supply blower to maintain a fixed precalibrated relationship between supply and return flow rates or by a further proportional plus reset controller responsive to the supply flow rate, for establishing the set point thereof, and to the return flow rate, as a feedback signal thereto, for controlling the output of the return blower.

Abstract: The pressure acting on a pressure loaded cheek plate in a pump is selectively vented by a servo valve actuated by the buildup of pressure in the pump outlet caused by normal parasitic losses in a downstream hydraulic flow circuit. Since it may be desirable to actuate the servo valve by the pressure drop across an orifice in the outlet line or by a suitable orifice in the pump return to pump, both embodiments are disclosed as exemplary means for achieving the premises of this design.