A positive displacement machine includes a case including a tubular guide part in which a pressure chamber is provided, a slide member including a shaft extending in a first direction and a piston provided at an end portion of the shaft and disposed in the guide part, a coupling member coupled to the slide member and extending in a second direction intersecting the first direction, a first rotating member coupled to one end of the coupling member and configured to rotate around a first rotation axis extending in the second direction, and a rocking absorbing mechanism configured to absorb a rocking motion of the piston around an axis extending in the first direction. The rocking absorbing mechanism is provided between the coupling member and the slide member, between the shaft and the piston, or between the piston and an inner wall of the guide part.

A compressor is disclosed. A compressor according to the present discloser includes a piston structure which has a guide member reciprocating inside a cylinder in an axial direction, and a magnet frame which supports a mover moving together with the piston structure, in which the piston structure includes the guide member, a mount member connected to the magnet frame, and an elastic member provided between the guide member and the mount member and capable of elastic deformation.

A reciprocating compressor is provided that may include a shell including a vibration absorbing member formed to be wound around an outer circumferential surface or an inner circumferential surface or stacked thereon, so that compressor vibration may be attenuated by frictional contact between the shell and the vibration absorbing member or between layers of the vibration absorbing member. Also a noise insulating layer may be formed between the shell and the vibration absorbing member or between the layers of the vibration absorbing member, so that a magnitude of noise may be reduced as vibration noise passes through the noise insulating layer, whereby vibration noise of the compressor, such as noise of a high frequency band, may be further attenuated by fine vibration.

A reciprocating-piston machine, in particular a two-stage or multi-stage piston compressor, includes: a first connecting rod for deflecting a first piston and which has a connecting-rod eye, the first connecting rod being a drive connecting rod; a second connecting rod for deflecting a second piston and which has at least one further connecting-rod eye, the second connecting rod being a follower connecting rod; a coupling element which extends through the connecting-rod eye and the at least one further connecting-rod eye and about which the first connecting rod and the second connecting rod are rotationally movable relative to one another; a coupling bearing element arranged between the coupling element and a connecting-rod eye inner surface of the connecting-rod eye; and a damping element with elastic damping action arranged in a damping annular chamber between the coupling bearing element and the connecting-rod eye inner surface of the connecting-rod eye.

A lubricator for a plunger lift system includes a tubular body, a shift rod housing, a first spring, and a second spring. The shift rod housing disposed in the tubular body and has a chamber. The shift rod has a first portion slidably disposed in the chamber and a second portion projecting from a first end of the shift rod housing. A distal end of the second portion of the shift rod is engageable with a shift valve of a bypass plunger. The first spring disposed in the chamber to absorb an impact force applied to the shift rod by the shift valve. The second spring disposed in the tubular body between a portion of the shift rod housing and a portion of the tubular body to absorb an impact force applied to the shift rod housing by a plunger body of the bypass plunger.

A compressor is disclosed. The compressor compressing and discharging a refrigerant sucked into a cylinder includes a cylinder forming a compression space of the refrigerant and having a cylindrical shape; a piston configured to reciprocate in the cylinder along an axial direction and having a cylindrical shape; a suction valve disposed at a front of the piston; a plate disposed in a rear of the piston, the plate comprising a flow groove into which the refrigerant is sucked; and a rod extending along the axial direction, one end of the rod being disposed on the suction valve, and other end of the rod being disposed on the plate.

Apparatus for compressing cryogenic fluid in at least one compression stage comprising at least one piston and at least one sleeve delimiting at least one compression chamber, a shaft that is able to move in translation along a longitudinal axis (A), the shaft being connected to the piston(s) or sleeve(s) and being able to move with an alternating movement in two opposite directions to ensure phases of compression and intake of fluid into the at least one compression chamber by moving the at least one piston and the at least one sleeve in a relative manner, characterized in that the shaft comprises a portion of reduced cross section in the longitudinal direction (A), said portion of reduced cross section separating two adjacent parts of the shaft, the shaft also comprising at least one linking element made of material that is less thermally conductive than the constituent material of the shaft, in particular a composite material, said at least one linking element having two ends connected respectively to the two adjacent parts of the shaft.

A compressor is disclosed. A compressor according to the present discloser includes a piston structure which has a guide member reciprocating inside a cylinder in an axial direction, and a magnet frame which supports a mover moving together with the piston structure, in which the piston structure includes the guide member, a mount member connected to the magnet frame, and an elastic member provided between the guide member and the mount member and capable of elastic deformation.

A lubricator for a plunger lift system includes a tubular body, a shift rod housing, a first spring, and a second spring. The tubular body has a sidewall and a closed end. The shift rod housing is disposed in the tubular body and has a chamber, a first end, and a second end. The shift rod has a first portion which is slidably disposed in the chamber of the shift rod housing and a second portion projecting from the first end of the shift rod housing. A distal end of the second portion of the shift rod is engageable with a shift valve of a bypass plunger. The first spring is disposed in the chamber of the shift rod housing in a way to absorb an impact force applied to the shift rod by the shift valve of the bypass plunger. The second spring is disposed in the tubular body between a portion of the shift rod housing and a portion of the tubular body in a way to absorb an impact force applied to the shift rod housing by a plunger body of the bypass plunger.

A compressor is disclosed. The compressor compressing and discharging a refrigerant sucked into a cylinder includes a cylinder forming a compression space of the refrigerant and having a cylindrical shape; a piston configured to reciprocate in the cylinder along an axial direction and having a cylindrical shape; a suction valve disposed at a front of the piston; a plate disposed in a rear of the piston, the plate comprising a flow groove into which the refrigerant is sucked; and a rod extending along the axial direction, one end of the rod being disposed on the suction valve, and other end of the rod being disposed on the plate.