A dry-type primary vacuum pump includes an injection device to distribute a purging gas in the pumping stages. The injection device includes: a first pressure sensor arranged on a common portion of the distributor, a second pressure sensor arranged on each branch of the distributor, and a control unit to generate a pulse width modulation command signal for the control of the regulation valves independently of one another as a function of the pressure measurement differences between the first pressure sensor and the second pressure sensors.

Provided are a pump body assembly and an assembly method therefor. The pump body assembly includes a first cylinder assembly (10), a second cylinder assembly (20) and a third cylinder assembly (30) sequentially arranged in a vertical direction. At least one of the first cylinder assembly (10), the second cylinder assembly (20) and the third cylinder assembly (30) is provided with a positioning detection portion (40).

A scroll compressor includes a hermetic container, a fixed scroll, a swing scroll, a frame, an electric motor, and a shaft. A first groove and a second groove are provided outside a fixed wrap in a radial direction at an end plate surface of the fixed scroll. An oil supply hole for guiding lubricant oil from a through-hole opens at an end plate surface of the swing scroll. A single opening of the oil supply hole alternately communicates with the first groove and the second groove along with swing of the swing scroll.

A compressor installation structure for a vehicle has: a first compressor that is installed in a vehicle and that is driven by a first displacement body repeating a first movement at a predetermined cycle; and a second compressor that is installed in the vehicle and that is driven by a second displacement body repeating a second movement at the predetermined cycle, wherein, in a state in which the first compressor and the second compressor are installed in the vehicle, a first displacement direction of a first centroid of the first displacement body at a time at which the first displacement body performs the first movement is an opposite direction from a second displacement direction of a second centroid of the second displacement body at a time at which the second displacement body performs the second movement.

The distance between openings of two supply passages that are closest to an accommodating recess is less than the distance between openings of two injection ports that are closest to compression chambers. This configuration minimizes the volume of the space in the accommodating recess between a check valve and the two supply passages, unlike a case in which the distance between the openings of the supply passages that are closest to the accommodating recess is greater than or equal to the distance between the openings of the two injection ports that are closest to the compression chambers. This reduces the flow rate of refrigerant that flows into the accommodating recess from the compression chambers in a compression process through the injection ports and the supply passages.

A suction fitting coupled to a scroll compressor that has an outer housing with an inside diameter and a suction port defined in a wall of the outer housing. A suction duct is disposed inside the outer housing at a spaced distance from the wall of the outer housing. The suction duct defines an entrance port aligned with the suction port. The suction fitting includes a first member being generally cylindrical, and a second member being generally cylindrical. The second member is disposed inside the first member with a portion of the second member extending into the outer housing through the suction port, spanning the spaced distance to the suction duct, and coupling with the entrance port of the suction duct. Neither the first member nor the second member includes a suction screen for filtering out solid contaminants in a flow of refrigerant.

An electric compressor includes: a circuit board on which a plurality of switching elements (33) are mounted; a compression mechanism which is driven by a motor operated using AC power output from the switching elements (33); and a lead holding member (50) disposed between element main bodies (33a) of the switching elements (33) and the circuit board. The circuit board includes a plurality of through-holes through which a plurality of leads (33b) that extend from the element main bodies (33a) can be respectively inserted. The lead holding member (50) includes lead insertion holes (53) through which the leads (33b) can be inserted such that positions of the leads (33b) is held at positions that correspond to positions of the through-holes.

A rotary compressor includes a compression mechanism having a cylinder, a piston, and a Helmholtz muffler. The Helmholtz muffler has a resonance chamber in the compression mechanism and a communication groove formed on an end face of the cylinder to connect the cylinder and resonance chambers. The communication groove is open at the end face of the cylinder and has a pair of side wall portions and a bottom wall portion between the side wall portions. Each side wall portion has a first portion adjacent an open end of the communication groove and a second portion adjacent the bottom wall portion. A surface of the first portion is a flat or bowed surface. A surface of the second portion is a bowed surface having a predetermined curvature so as to be connected to the surface of the first portion and a surface of the bottom wall portion.

A gas compressor includes inverters, a plurality of compressor units and a control device for controlling each of the inverters. The control device increases the number of compressor bodies to be operated after confirming that the rotational speed of the operational motors will reach a steady value immediately after causing the number of the compressor bodies to be operated to increase.

The present disclosure relates to a compressor including a branch part for reducing vibration and noise caused by a refrigerant flowing inside a muffler by expanding an enclosed space formed by a compression part and the muffler in the direction of a rotation axis.