A gerotor pump having an inner rotor and an outer rotor, which is also the rotor of an electric drive, having a housing and a flange which closes the housing with the motor compartment, the rotor being arranged on a shaft and sealing against the flange at a gap, wherein, in addition to the gap, there is at least one device with which at least a partial pressure compensation takes place between the suction region of the gerotor pump and the motor compartment of the gerotor pump.

An improved screw pump such as, for example, a twin screw pump is disclosed. In one embodiment, the screw pump includes a casing, first and second intermeshing rotors, and a liner positioned between the first and second rotors and the casing. In use, the liner is arranged and configured to bend and/or pivot in unison with the first and second rotors under the axial hydraulic pressure experienced by the screw pump during use. In one embodiment, the liner may be arranged and configured to include an asymmetric axial stiffness to facilitate bending of the liner. In another embodiment, the liner may be arranged and configured in multiple segments, the segments being arranged and configured to pivot to approximate the bending of the rotor shafts.

An eccentric screw pump with a rotor (2) and with a rotationally fixed stator (6; 6′) surrounding the rotor (2). The rotationally fixed stator includes at least one elastomeric portion, wherein a pressure chamber (16) is arranged on this elastomeric portion of the stator (6; 6′) at a side facing away from the rotor (2). The pressure chamber (16) is connected to a pressure region of the eccentric screw pump such that the at least one elastomeric portion of the stator (6; 6′) is subjected to a pressure produced by the eccentric screw pump.

An example hydraulic motor comprises: a stator comprising (i) a stator body having plurality of roller pockets, wherein the stator body comprises a plurality of grooves that are longitudinally-extending, and (ii) a plurality of rollers disposed respectively in the plurality of roller pockets; a rotor having a plurality of external teeth configured to engage with the plurality of rollers of the stator, such that the plurality of rollers and the plurality of external teeth define fluid chambers therebetween configured to expand and contract as the rotor rotates within the stator; and an anti-cogging passage configured to provide pressurized fluid from at least one of the fluid chambers to at least one groove of the plurality of grooves of the stator body, such that pressurized fluid provided to the at least one groove applies a radially-inward force on a respective roller toward the rotor.

The application relates to an internal gear machine for reversing duty having a housing with a chamber, in the chamber there are disposed an externally toothed pinion and an internally toothed ring gear, which mesh with one another, the rotational axes of which run parallel to and spaced apart from one another. The chamber in the housing is axially bounded and is connected via pressure pockets provided in the housing to pressure connections in the internal gear machine. According to the invention, a switching valve is arranged in each connection between the pressure pockets and the pressure connections or compression spaces, which valve opens or closes the connection.

A gerotor pump having an inner rotor and an outer rotor, which is also the rotor of an electric drive, having a housing and a flange which closes the housing with the motor compartment, the rotor being arranged on a shaft and sealing against the flange at a gap, wherein, in addition to the gap, there is at least one device with which at least a partial pressure compensation takes place between the suction region of the gerotor pump and the motor compartment of the gerotor pump.

In a gear pump, a gear chamber is defined in a housing hole of a housing. A pair of gears is housed in the gear chamber. The gears are rotatably supported at support holes of a pair of side plates via support shafts. As viewed in an axial direction of the support shafts during rotation of the gears, addendum circles of the gears displaced under a differential pressure between a low-pressure chamber and a high-pressure chamber form first contact points with respect to an inner peripheral surface that defines a housing hole. As viewed in the axial direction of the support shafts during rotation of the gears, the first contact points are covered with the side plates displaced under the differential pressure.

An oil pump, in particular an electric or electromotive auxiliary pump for a motor vehicle, having a housing having an inlet on the admission side and an outlet on the pressure side, in addition to a pump rotor which is inserted in the housing such that it can rotate about an axis, and having at least one rotor part, a flexible housing component which is in the form of an elastic press plate and which extends over the cross-sectional surface of the pump rotor. The flexible pressure plate is maintained, in an advantageous manner, in the edge area of the second housing parts.

A gerotor pump having an inner rotor and an outer rotor, which is also the rotor of an electric drive, having a housing and a flange which closes the housing with the motor compartment, the rotor being arranged on a shaft and sealing against the flange at a gap, wherein, in addition to the gap, there is at least one device with which at least a partial pressure compensation takes place between the suction region of the gerotor pump and the motor compartment of the gerotor pump.

A highly reliable horizontal rotary compressor is provided with a sealed housing, an electric motor, a compression mechanism, a frame which divides the inside of the sealed housing into an electric-motor chamber and a compression-mechanism chamber, and a plurality of bolts that fasten the compression mechanism to the frame. The compression mechanism includes a main bearing fasten to the end surface of a cylinder. A bearing contact-surface of the end surface of the cylinder is in contact with the main bearing, is located closer to the electric motor than a frame contact-surface which is in contact with the frame. The surface roughness of the frame contact-surface is greater than the surface roughness of the bearing contact-surface. The contact-surface of the frame is a single continuous flat surface located above the bolt located at the lowest position among the plurality of bolts.