Methods and apparatus pertaining to positive displacement pumps, and further to hydraulic actuation systems. In some embodiments the pumps are gear pumps with bi-directional operation. In some embodiments the actuation system includes a motor-driven, reversible operation gear pump providing fluid under pressure to a rod and cylinder.

A transfer pump configured to move a hydraulic fluid in a hydraulic fluid management system of a hydraulic system of a vehicle including a transmission. In one embodiment, the transfer pump moves the fluid from a differential case to a hydraulic reservoir coupled to the transmission. The transfer pump is a positive displacement pump including an unloading device, such as a sealing plate, that is resiliently biased against the pump during a normal operation but is moved away from the pump upon the application of a pilot pressure. The result is an open chamber for the pump gears to turn without developing pressure, to thereby reduce parasitic losses.

An electric pump includes a motor unit rotationally driving a drive shaft, and a pump unit. The pump unit includes a pump rotor that sends the fluid by a driving force of the driving shaft, and a pump housing that covers at least one side of the pump rotor. The pump housing includes an attachment surface extending in the axial direction and in contact with an attached body, first and second flow paths respectively on the suction side and the discharge side, and a partition wall positioned between pump-side openings of the first flow path and the second flow path facing the pump rotor, and extends in a direction along the attachment surface, and locations of attachment-side openings of the first flow path and the second flow path on the attachment surface are displaced from each other on the attachment surface in the axial direction.

An outlet gasket which has a gasket structure made of a gasket material, for sealing off a first pressure outlet and a second pressure outlet of a pump, the gasket structure including: a first sealing stay which circumferentially encloses a first fluid passage of the outlet gasket, provided for the first pressure outlet, in a seal in an axial plan view onto the outlet gasket; and a second sealing stay which circumferentially encloses a second fluid passage of the outlet gasket, provided for the second pressure outlet and located laterally next to the first fluid passage, in a seal in the plan view, wherein the gasket structure forms the sealing stays contiguously as a unit, and/or the outlet gasket includes a support structure on which the sealing stays are arranged.

A fluid pump includes a gear housing with a pocket wall and a base. The pocket wall and the base define a pocket that projects into the gear housing from a pocket surface. The fluid pump also includes a first gear rotatably positioned in the pocket. The first gear is spaced from the pocket surface by a first gap. The fluid pump also includes a second gear rotatably positioned in the pocket that engages the first gear. The second gear is spaced from the pocket surface by a second gap. The fluid pump also includes a selected shim that is selected from a plurality of shims in a shim set. The selected shim has a thickness that results in a desired clearance between the selected shim and the first face or the second face.

A gear pump or a gear motor includes a casing, a helical drive gear, a helical driven gear, a drive-side space, and an idler-side space. The drive and driven gears mesh with each other in the casing to partition inside of the casing so as to include high and low pressure spaces. The drive-side and idler-side spaces are each configured to allow pressure therein to become higher than a pressure in the low-pressure space. The drive-side space faces an end portion of a drive shaft rotatably supporting the drive gear. The idler-side space faces an end portion of an idler shaft rotatably supporting the driven gear. The end portion of the drive shaft is pushed in a predetermined direction by working fluid supplied to the drive-side space. The end portion of the idler shaft is pushed in the predetermined direction by working fluid supplied to the idler-side space.

A bearing structure for abutting a pair of gears of a gear pump includes a body including a face on which the gears rotate, an inlet defined in the body, and an outlet defined in the body. The bearing structure includes a sealing portion of the face configured to fluidly seal the inlet from the outlet, the sealing portion being defined as a portion of the face in sealing engagement with the gears at a rotational position of the gears wherein a volume contained by teeth of the gears and the face is constant or about constant as the gears rotate.

A fluid pump, in particular an oil pump, for supplying a clutch actuator, a gearbox actuator, a lubrication system, and/or a cooling system of a drive train, includes a pump unit, an electrical drive unit, and a one-piece sealing element. The pump unit is arranged in a first housing part of the fluid pump, and the electrical drive unit is arranged in a second housing part of the fluid pump. The one-piece sealing element seals the first housing part against the second housing part, and seals the first housing part against a housing cover arranged on a side opposite the second housing part. Furthermore, a method for producing such a fluid pump includes arranging a pump unit in a first housing part of the fluid pump and moulding a sealing element onto the first housing part.

An electric pump includes a motor unit rotationally driving a drive shaft, and a pump unit. The pump unit includes a pump rotor that sends the fluid by a driving force of the driving shaft, and a pump housing that surrounds at least one side of the pump rotor. The pump housing includes an attachment surface extending in the axial direction and in contact with an attached body, first and second flow paths respectively on the suction side and the discharge side, and a fixing location within the attachment surface and fixed to the attached body by a fixing member within a maximum outer shape of the motor housing as viewed in the axial direction. Opening locations of the first and second flow paths are displaced from each other in the axial direction on the attachment surface.

A sealing arrangement is disclosed for use in a pump. The sealing arrangement can include a first pump component having a first face surface. The first face surface can have a sealing protrusion thereon. A second pump component can have a second face surface positioned in confronting relation to the first face surface. The second pump component can define a sealing cavity for holding a fluid under pressure. The sealing protrusion is positioned to engage the second face surface when the first face surface is pressed against the second face surface so that the sealing protrusion seals against the second face surface to prevent movement of the fluid from the sealing cavity past the sealing protrusion. Other embodiments are described and claimed.