Disclosed is a screw compressor having a slide valve with a flexible volume ratio, which includes: a casing, a screw, an air entry, an air outlet, a slide valve, a first air cylinder and a second air cylinder. The slide valve is disposed between the first air cylinder and the second air cylinder, and includes a slide valve main body. Two ends of the slide valve are respectively a first end surface and a second end surface, and the first end surface and the second end surface seal the first air cylinder and the second air cylinder respectively. The first air cylinder is connected to the air outlet of the compressor through a first connection pipe, and the second air cylinder is connected to a last closed spiral flute trough a second connection pipe. The slide valve searches for balance under the driving of pressures in the first air cylinder and the second air cylinder. The screw compressor having a slide valve with a flexible volume ratio provided by the present invention can enable the volume ratio of the compressor to be automatically adjusted to an optimal state, thus reducing power consumption and noise.

A motor-driven compressor includes a back pressure region (62, 27a) that pushes a movable scroll (23) against a fixed scroll (22). The back pressure region (62, 27a) is located at a side of the movable scroll (23) located proximate to an opposing member (21, 24). A defining portion (23e), which is arranged on a movable end face, contact an opposing end face (24b) to define the back pressure region (62, 27a) and a suction pressure region (121, 211, 24h, 32, 221 h, 31). The opposing member (21 24) includes a communicating portion (21e, 24a). An orbiting motion of the movable scroll (23) moves the defining portion (23e). This intermittently communicates the communicating portion (21e, 24a) with the back pressure region (62, 27a) and the suction pressure region (121, 211, 24h, 32, 221h, 31).

A rotary compressor (1) includes an oiling mechanism (159) that contains a vertical fitting hole (155b) formed on a countershaft portion (151) in the lower part of the rotating shaft (15), and an oil pipe (16) having an inlet port (16a) at the lower end and an opening at the upper end. The upper part of the oil pipe is press-fitted into the vertical fitting hole (155b). The oiling mechanism further contains a pump vane (157) having a vane portion (157a) and a base portion (157b). The vane portion is twisting processed and inserted into the vertical oil hole (155) to provide a space. The base portion is fixed into the lower part of the oil pipe that has an inner diameter (φD₁) smaller than the width thereof (H₁).

There is provided a vane compressor including a plurality of vanes that performs a compression operation such that the normal to a circular arc formed by each vane tip portion and the normal to the inner peripheral surface of a cylinder are constantly approximately coincident with each other. In the vane compressor according to the present invention, each of the plurality of vanes is held to be constantly in the normal direction of the inner peripheral surface of the cylinder or is held to be constantly along a direction having a fixed inclination with respect to the normal direction of the inner peripheral surface of the cylinder so that the compression operation is performed in the state where the normal to the circular arc formed by the tip portion of each of the plurality of vanes and the normal to the inner peripheral surface of the cylinder are constantly approximately coincident with each other. Further, the plurality of vanes are rotatably and movably supported with respect to the rotor portion in the rotor portion. A concave portion or a ring-shaped groove being concentric with the inner diameter of the cylinder is formed in an end surface of each of the cylinder head and the frame on the side of the cylinder, a pair of vane aligners are fitted in the concave portion or the ring-shaped groove, and a plate-like projection or a groove of each of the vane aligners is fitted in a groove or a projection provided at each of the plurality of vanes. Each of the vane aligners includes the plate-like projection or the groove at a partial-ring-shaped end surface thereof.

A gas transfer machine for use as a vacuum pump, for example, has a pump rotor mounted on a rotatable shaft for transferring a gas, and a reluctance-type motor for rotating the rotatable shaft. The reluctance-type motor has a stator, a motor rotor surrounded by the stator, and a shield member isolating the stator from the motor rotor. The motor rotor is directly coupled to the rotatable shaft and has a plurality of magnetic salient poles.

Separation of resin layers formed on the end face or the like of a piston in a compressor is prevented while the reduction in compressor efficiency is minimized. The compressor includes: a cylinder having a compression chamber, and a blade housing in communication with the compression chamber; a front head and a rear head provided on both ends of the cylinder; and a piston provided inside the compression chamber and blade housing. The piston has an annular roller provided in the compression chamber, and a blade extending from the outer circumferential surface of the roller, the blade being able to advance and retract with respect to the blade housing. Resin layers (44a, 44b) obtained by layering four layers are formed on the axial end faces of the piston. In the resin layers (44a, 44b), the hardness of the fourth layer farthest from a base material (43) is lower than the hardness of the first layer closest to the base material (43), and the difference in hardness between adjacent layers (L1-L2, L2 - L3, L3 - L4) is less than the difference in hardness (L1-L4) between the fourth layer farthest from the base material (43) and the first layer closest to the base material.

The purpose of the present invention is to reduce frictional loss on the surface of a resin layer by sliding in a compressor when the surface contacts with an opposed member and slides. A compressor has a resin layer that is formed on the whole area or a portion of a part that serves as one sliding surface of a sliding member that can slide upon the compression of a cooling medium. The resin layer has an arithmetic mean surface roughness (Ra) of 0.3 or more, or the whole area or a portion of an area that faces the resin layer has higher hardness than that of the resin layer and has an arithmetic mean surface roughness (Ra) of 0.3 or more.

While using an Oldham mechanism as a spin prevention unit mechanism, an Oldham ring is positively lubricated by keeping a medium mixe with oil on a back surface of a turning scroll, and a compression mechanism is kept compact. In a scroll type compressor in which an Oldham ring (18) is provided between a turning scroll member (11) and a block member (5) that axially supports a drive shaft, a fixed scroll member (10) and the block members (5) hold an annular thrust race (16) that receives a load in an axial direction from the turning scroll member (11) with the thrust race sandwiched therebetween, an end of the turning scroll member (11) is slidably brought into close contact with the thrust race (16) on an entire circumference thereof, the thrust race (16) is brought into close contact with the end surface of the block member (5) to the outer side in a radial direction beyond key groove portions (25b, 25c) which are paired and formed on the block member (5), the turning scroll member (11), the thrust race (16), and the block member (5) define a retention space, and the medium with oil is retained in the retention space.