A compression unit of a rotary compressor includes a cylinder, an upper end plate that closes the upper side of the cylinder, a lower end plate that closes the lower side of the cylinder, and a piston that is fitted to a rotating shaft, revolves along an inner peripheral surface of the cylinder, and forms a cylinder chamber in the cylinder. At least one of an end face of the piston in the axial direction of the rotating shaft, a sliding surface of the upper end plate that slides with the end face of the piston, and a sliding surface of the lower end plate that slides with the end face of the piston, has formed therein an oil-film retention region having an array of a plurality of recessed portions that retain lubricating oil.

Disclosed are an outer ring for an oil pump having an increased number and size of open pores in a surface of a molded article and a method for manufacturing the outer ring.

A screw compressor for a utility vehicle has at least one female screw, at least one male screw that meshes with the female screw, and at least one screw compressor drive which drives the female screw.

A multi-stage rotary vane pump comprising at least two rotor elements. The rotor elements are supported by a rotor shaft. The rotor elements and the rotor shaft are in the form of a single piece.

Rotor and/or stator designs and methods thereof to improve progressive cavity motor or pump durability. In one or more implementations, the rotor may have a variable outer diameter or variable stiffness along an axial length thereof. The stator may similarly have a variable inner diameter or variable stiffness, which may compliment or diverge from the variable outer diameter or variable stiffness of the rotor.

A ring section pump features a low-pressure end configured to receive fluid to be pumped into the ring section pump; a high-pressure end configured to provide the fluid to be pumped from the ring section pump; and an intermediate tie rod combination having a intermediate flange with upper tie rods configured to couple together the intermediate flange and the high-pressure end and with lower tie rods configured to couple together the intermediate flange and the low-pressure end. The low-pressure end has an inlet flange; the high-pressure end has an outlet/discharge flange; and the upper tie rods couple together the intermediate flange and the outlet/discharge flange and the lower tie rods couple together the intermediate flange and the inlet flange.

The present invention relates to rotary screw positive displacement machines used as a vacuum pump wherein additional intake air is provided allowing cooling to the invention which permits extended operation at extreme vacuum pressure. The rotary screw nature of the vacuum pump allows operation without additional lubrication with the additional intake air ensuring that thermal expansion will not disrupt the tight tolerances of the invention. The invention allows simultaneous operation as a vacuum pump and air compressor.

This pump comprises: a housing comprising a body and a first partition which separates first and second areas; a stator disposed in the housing; a circuit board disposed in the first area; a pump gear disposed in the second area; and magnets disposed on the pump gear, wherein the second area includes a second space defined by the first partition wall and the body, and the stator is inserted into the body.

A stacked gerotor pump is provided. The stacked gerotor pump includes a first gerotor pump defining a first inlet section and a first outlet section, a second gerotor pump defining a second inlet section and a second outlet section and a plate. The plate is interposed between the first and second gerotor pumps and defines upstream cavities respectively communicative with the first and second inlet sections, downstream cavities respectively communicative with the first and second outlet sections and a pre-pressurization hole by which the second outlet section is communicative with the first inlet section.

A rotary pump is presented for use in a medicament delivery device, where the pump has a back plate having an inner surface and a rotor housing is positioned adjacent to the back plate having a peripheral wall. A front plate support is connected to the back plate and a flexible front plate is positioned between the front plate support and the rotor housing. The pump is rotated using a planetary gear transmission, where an eccentric shaft is operatively connected to the planetary gear mechanism. A rotor is rotationally fixed to the eccentric shaft and movably positioned within the rotor housing. The rotor has three lobes, where each lobe has two peripheral curved surfaces sharing a common apex, where a first portion of each peripheral surface adjacent to the apex defines a non-smooth curve.