A vane pump (101) for an automatic transmission includes a suction-side behind-vane pressure duct (112) and a pressure-side behind-vane pressure duct (111). The suction-side behind-vane pressure duct (112) is connected to the pressure side (116) of the vane pump (1). A valve device (113, 114) is connected to the pressure-side behind-vane pressure duct (111). During operation of the vane pump (101), a pressure-side behind-vane pressure (p DH) can be set in the pressure-side behind-vane pressure duct (111) with the valve device (113, 114).

A cam ring is capable of moving while rolling on a cam support surface. The cam ring is provided such that within a range in which the cam ring can move on the cam support surface, an eccentricity amount increasing-side angle is always greater than an eccentricity amount decreasing-side angle. On a plane perpendicular to the rotation axis of a driving shaft, the eccentricity amount increasing-side angle is an angle, in a direction opposite to a rotation direction of the driving shaft, from a first reference line, which connects a tangent point between the cam ring and the cam support surface to a rolling center of the cam ring, to a starting end of a first discharge port. The eccentricity amount decreasing-side angle is an angle, in the rotation direction of the drive shaft, from the first reference line to a terminal end of the first discharge port.

A dual vane pump system includes first and second vane pumps having first and second rotors with a plurality of vanes moving radially inwardly and outwardly of the first and second rotors, and into contact with an inner surface of the first and second outer liners. A first pre-pressurization passage connects a first pump inlet in the first pump that is at discharge pressure to a second pump outlet in the second pump which is upstream of the second discharge opening. There is a coupling connecting the first and second rotors for rotation together. The pre-pressurization passage extending through the bearing.

A vane cell pump, including: a delivery chamber having an inlet and an outlet; a rotor which is arranged in the delivery chamber and has a rotor body and vanes which are accommodated by the rotor body such that they can be shifted radially; an end-facing wall which delineates the delivery chamber on an axial end-facing side; and a supporting element which is arranged axially between the end-facing wall and the rotor body and which supports the vanes at their radially inner vane ends, wherein the rotor body, the supporting element and each two vanes which are adjacent in the circumferential direction of the rotor form chambers, the volume of which varies when the rotor is rotating. A pressure equalization connection fluidically connects at least two of the chambers to each other.

A vane pump comprises a housing and a control slide. A rotor rotates to draw lubricant into a rotor receiving space of the slide via a housing inlet and discharges the lubricant via an outlet. The control slide moves to change its eccentricity relative to the rotor for increasing and decreasing a pressure differential between the inlet and outlet. The control slide is biased in a displacement increasing direction. The control slide has one or more seals defining a control chamber with housing. The one or more seals includes a seal assembly received in a recess on a control slide outer surface. The seal assembly has a base element in the recess and a bearing element pivotally attached to the base element and bearing against an inner surface of the housing for sealing. The pivotal attachment includes male and female pivotal connectors coupled together.

A vane pump device includes: a rotor supporting 10 vanes movable in a rotation direction; and a cam ring having an inner circumferential surface facing an outer surface of the rotor. A fluid-suction step where transits to a fluid-discharge step by changing the pump chamber capacity in response to the rotation angle, as a result of the change in the distance from the rotation center to the inner circumferential surface of the cam ring in response to the rotation angle. A starting angle, at which the distance starts increasing after a same distance segment has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle that equally divides a rotation angle at which a downstream-side end portion in the discharge port is formed and a rotation angle at which an upstream-side end portion in the suction port is formed.

A variable lubricant vane pump includes a pump housing, a shiftable control ring, a rotatable pump rotor, a control ring preload spring which preloads and pushes the control ring into a high eccentricity direction, a hydraulic safety control chamber which moves the control ring against the control ring preload spring and which is directly and constantly pressurized with a pressurized lubricant having a pump outlet pressure, a separate hydraulic adjustment control chamber which moves the control ring against the control ring preload spring and which is selectively pressurized with the pressurized lubricant having an over-atmospheric pressure, an electric adjustment valve which selectively directs the pressurized lubricant having the over-atmospheric pressure to the separate hydraulic adjustment control chamber, and a calibrated hydraulic channel which directly connects the separate hydraulic adjustment control chamber with atmospheric pressure. An effective hydraulic cross-sectional area of the calibrated hydraulic channel is less than 5.0 mm.sup.2.

A variable displacement pump according to the present invention is notably configured such that the opening area of a variable metering orifice (MO) is variably controlled by a second control valve (6) as a spool valve having a second spool valve body (61). According to this type of the second control valve (6), a larger amount of movement (stroke movement) of the second spool valve body (61) can be ensured. Consequently, the opening area of the variable metering orifice (MO) can be controlled without being restricted by a range of variation in a proper discharge amount based on an amount of movement of a cam ring (2), thereby achieving sufficient energy conservation of the pump.

In a variable displacement vane pump, a cam profile of a cam ring includes a deviation region deviating from a perfect-circle cam profile outwardly in a radial direction regarding a rotational axis of a driving shaft in an intake region.

A composite piston machine has two moving assemblies of a rotor and a composite piston placed 180° out of phase with each other and linked to a shaft eccentrically placed inside the inner cavity of a main body that has ports for the inlet and outlet of fluids from it. This inner cavity is covered by two lids and divided in two working chambers by a separator. The composite pistons move following the rotation of the rotors while oscillating with respect of them and following the path of skid guides carved in separator and lids, dividing each working chamber in inlet and outlet chambers of variable volume, and intermittently obstructing the inlet and outlet of fluids from the inner cavity through the ports. The machine is designed for compressing gases or pumping liquids and can also operate as an engine driven by compressed gases or with pressurized liquids.