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.

A rotary compressor is provided that may include a rotational shaft, first and second bearings configured to support the rotational shaft in a radial direction, a cylinder disposed between the first and second bearings to form a compression space, a rotor disposed in the compression space to form a contact point forming a predetermined gap with the cylinder and coupled to the rotational shaft to compress a refrigerant as the rotor rotates, and at least one vane slidably inserted into the rotor, the at least one each vane coming into contact with an inner peripheral surface of the cylinder to separate the compression space into a plurality of regions. The at least one vane may include a pin that extends upward or downward, and a lower surface of the first bearing or an upper surface of the second bearing may include a rail groove into which the pin may be inserted.

An inter-stage coupling for a multi-stage vacuum booster pump may include a first coupling face configured to be received by a first adjacent stage of the multi-stage vacuum pump; a second coupling face configured to be received by a second adjacent stage of the multi-stage vacuum pump; and a recirculator comprising a recirculation inlet aperture formed in the first coupling face, a recirculation outlet aperture formed in the first coupling face, and a recirculation conduit having a recirculation valve configured to selectively fluidly couple the recirculation inlet aperture with the recirculation outlet aperture. In this way, the pressure in a stage can be relieved by fluidly coupling the outlet aperture with the inlet aperture in order to recirculate built-up gas from one part of the first stage pump to another part of the first stage pump in order to reduce the strain on the rotor.

A scroll compressor including a housing, a motor provided in the housing, a rotary shaft rotated by the motor, an orbiting scroll configured to orbit in conjunction with the rotary shaft, and a fixed scroll configured to define compression chambers together with the orbiting scroll, in which the housing includes a center housing penetrated by the rotary shaft, a front housing configured to define, together with the center housing, a motor accommodation space that accommodates the motor, and a rear housing configured to define a discharge chamber that accommodates a refrigerant discharged from the compression chamber, and an injection valve assembly provided between the fixed scroll and the rear housing, and the injection valve assembly includes an anti-leakage means and an injection valve configured to open or close an injection flow path that guides the refrigerant, which is introduced from outside of the housing, to the compression chamber.

A hydraulic device is disclosed. The hydraulic device can include a rotor, a plurality of vanes and a ring. The ring can include a suction cavity and a pressure cavity. The suction cavity and pressure cavity can be configured for ingress and egress of a hydraulic fluid through the ring. The ring can include a suction port defined entirely by the ring and in fluid communication with the suction cavity. The suction port can be configured to receive hydraulic fluid from a first region between the ring and the rotor. The ring can include a pressure port defined entirely by the ring and in fluid communication with the pressure cavity. The pressure port can be configured to allow for passage of the hydraulic fluid from the pressure cavity to a second region between the ring and the rotor.

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.

An electric compressor includes a compression portion that compresses and discharges a drawn fluid, and a motor of the compression portion. The electric compressor includes an actuator that includes multiple electronic components and drives the motor, a first casing that accommodates the actuator, and a second casing that accommodates the compression portion and the motor. The second casing includes a discharge passage in which a high-temperature fluid compressed by the compression portion flows. A limiting structure that limits the heat transfer from the fluid flowing in the discharge passage is provided between one of the electronic components and the discharge passage. The limiting structure includes a seat portion that defines a gap between a bottom surface of the one of the plurality of electronic components and the discharge passage. According to the electric compressor, the heat transfer from the fluid to the electronic components can be limited.

A suction side end part of a suction guide passage and a discharge side end part of a discharge guide passage are opposed to each other with a gap therebetween. At a deviation angle at which contraction of a pump chamber starts, an outer peripheral part of the discharge side end part is formed along an inner tooth, and an inner peripheral part of the discharge side end part is formed along an outer tooth. A working tool that rotates and cuts circularly is moved around on a pump housing in a single continuous line to form an outline of the discharge guide passage, thereby forming the discharge guide passage. The working tool is moved around on the pump housing in a single continuous line to form an outline of the suction guide passage, thereby forming the suction guide passage.

An outer gear and an inner gear expand and contract volume of pump chambers formed between both the gears, and rotate to suction fuel into the pump chambers and then discharge fuel from the pump chambers sequentially. The inner gear includes an insertion hole that is depressed along its axial direction. A joint member includes a main body portion that is fitted to a rotary shaft, a foot portion that extends from the main body portion along the axial direction and is inserted in the insertion hole with a clearance therebetween, and a protruding portion that protrudes from the foot portion toward a rotation progress side of the inner gear and has its width in the axial direction further narrowed toward a top portion of the protruding portion.

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.