Improved bushing assembly (10) for supporting the shafts of the intermeshed rotors of a positive displacement rotary pump avoiding, jamming, said bushing assembly (10) comprising on a lateral surface (13) thereof at least one compensation tank (15; 16) facing a suction side of the pump and at least one bleed channel (14) which connects said compensation tank (15; 16) to the discharge side.

An electric hydraulic pump for a transmission includes: a motor including a motor cover, a motor case coupled with the motor cover, and a stator and a rotor disposed within the motor cover and the motor case; and a pump including a pump case forming a pump chamber, and a gear rotor which is disposed within the pump chamber, connected with the rotor through a motor shaft and receives rotational power of the motor. In particular, a plurality of oil circulation holes are formed in the motor cover and a connecting hole is formed in the motor cover corresponding to the pump case, and an oil flow channel is formed within the pump case for connecting the connecting hole and an oil inlet of the pump chamber.

An electric hydraulic pump for a transmission includes: a motor including a motor cover, a motor case coupled with the motor cover, and a stator and a rotor disposed within the motor cover and the motor case; and a pump including a pump case forming a pump chamber, and a gear rotor which is disposed within the pump chamber, connected with the rotor through a motor shaft and receives rotational power of the motor. In particular, a plurality of oil circulation holes are formed in the motor cover and a connecting hole is formed in the motor cover corresponding to the pump case, and an oil flow channel is formed within the pump case for connecting the connecting hole and an oil inlet of the pump chamber.

A gear pump having a drive shaft and at least two gear wheel pairs which each include a drive gear wheel and a driven gear wheel. The two gear wheels of a gear wheel pair are in meshing engagement with one another, and the drive gear wheels are arranged on the drive shaft and in torque-transmissive engagement with the drive shaft. The gear pump has a freely rotatably mounted shaft on which the driven gear wheels of the gear wheel pair are arranged in torque-transmissive engagement, wherein the driven gear wheels are mounted on the freely rotatably mounted shaft by means of a clearance fit.

The invention relates to a screw pump (1), in particular a double screw pump, s comprising a multiple-piece housing (2, 7, 15, 21) and at least two coupled rotors (3, 3a) which form chambers with in each case at least one thread-shaped profile (4, 4a) which is configured at least in regions with helical channels (5, 5a) and with dividing walls (6, 6a) which delimit the channels (5, 5a), wherein the rotors (3, 3a) perform an opposed rotor rotation, and the dividing walls (6, 6a) engage into one another in a gearwheel-like manner, a running housing part (7), wherein the running housing part (7) encloses the rotors (3, 3a) without contact, wherein the rotors (3, 3a) form, with the running housing part (7), at least one conveying chamber (8, 8a) for the fluid to be conveyed, wherein the conveying chamber (8, 8a) migrates axially along the rotor axis (10, 10a) and conveys the fluid from a suction chamber (11) into a pressure chamber (12), a suction-side connector element (13) which is connected fluidically to the suction chamber (11), and a pressure-side connector element (14) which is connected fluidically to the pressure chamber (12), wherein the suction-side connector element (13) and the pressure-side connector element (14) are arranged on a connector housing part (15) of the multiple-piece housing (2, 7, 15, 21), wherein the housing (2, 7, 15, 21) has a planar dividing plane (16) which runs parallel to the rotor axes (10, 10a) between the running housing part (7) and the connector housing part (15).

A pump includes a casing defining an interior volume. The pump casing includes at least one balancing plate that can be part of a wall of the pump casing with each balancing plate including a protruding portion having two recesses. Each recess is configured to accept one end of a fluid driver. The balancing plate aligns the fluid displacement members with respect to each other such that the fluid displacement members can pump the fluid when rotated. The balancing plates can include cooling grooves connecting the respective recesses. The cooling grooves ensure that some of the liquid being transferred in the internal volume is directed to bearings disposed in the recesses as the fluid drivers rotate.

A pump includes a casing defining an interior volume. The pump casing includes at least one balancing plate that can be part of a wall of the pump casing with each balancing plate including a protruding portion having two recesses. Each recess is configured to accept one end of a fluid driver. The balancing plate aligns the fluid displacement members with respect to each other such that the fluid displacement members can pump the fluid when rotated. The balancing plates can include cooling grooves connecting the respective recesses. The cooling grooves ensure that some of the liquid being transferred in the internal volume is directed to bearings disposed in the recesses as the fluid drivers rotate.

A pump device includes a rotating body, a pump housing including a suction port and a discharge port, and a relief valve. In the pump device, a fluid is sucked from the suction port and discharged from the discharge port by rotation of the rotating body. The relief valve includes a valve body and a biasing member. The discharge port includes an one end in a direction in which the discharge port extends. The one end is shallower than a middle portion of the discharge port. The pump housing includes a relief flow path through which the fluid flows when the relief valve opens. The relief flow path is provided so as to be open to a groove bottom surface of the one end of the discharge port.

A gear pump or a gear motor in which a tooth groove is easily filled with a liquid. A gear pump includes a casing, a gear storage chamber, a suction passage, a discharge passage, a gear that is housed in the gear storage chamber and including a drive gear and a driven gear that rotate while meshing with each other, and a suction-side communication path that connects a first space and a tooth groove of the gear, the first space being a closed space formed by the drive gear and the driven gear meshing with each other, the tooth groove being opened to the suction passage.

A groove is applied to one or more contact surfaces of a journal bearing of a pump to increase a force applied to the contact surface(s). Each groove has an end exposed to discharge pressure of the pump so that the groove communicates the discharge pressure across the contact surface. The groove reduces an area of the contact surface over which fluid leakage results in a pressure differential, thereby increasing a net force applied to the contact surface. Applying the groove to the axial end face of the journal bearing enhances an axial force applied to the journal bearing whereas applying the groove to a radially facing land reduces friction between the journal bearing and the outer housing.