An oil-free screw compressor has a screw rotor including a screw and a shaft, a bearing supporting the shaft, a first shaft seal device disposed between the screw and the bearing and including a first seal opposite to the shaft, and a first communication portion communicating the bearing side with respect to between the shaft and the first seal and the outer peripheral face of the first shaft seal device, and a second shaft seal device disposed between the first shaft seal device and the bearing and including a second seal opposite to the shaft, and a second communication portion communicating the screw side with respect to between the shaft and the second seal and the outer peripheral face of the second shaft seal device. A casing includes an atmosphere communication portion connected to both of the first communication portion and the second communication portion on the inner peripheral face of a shaft accommodation space, and communicating the first communication portion and the second communication portion with the atmosphere.

A scroll compressor according to the present disclosure includes a fixed scroll, an orbiting scroll forming first and compression chambers with the fixed scroll, first and second compression chamber oil supply holes formed through the orbiting scroll to communicate with the first compression chamber and the second compression chamber, respectively, wherein when a section in which the first compression chamber oil supply hole is opened toward the first compression chamber is a first oil supply section and a section in which the second compression chamber oil supply hole is opened toward the second compression chamber, a non-overlap section between the first oil supply section and the second oil supply section may be longer than an overlap section between the first oil supply section and the second oil supply section, so as to prevent communication between the first and second compression chambers, thereby suppressing leakage between the compression chambers.

A scroll compressor is provided that may include an orbiting scroll having an orbiting wrap, and which performs an orbiting motion; and a fixed scroll having a fixed wrap to form a compression chamber including a suction chamber, an intermediate pressure chamber, and a discharge chamber, by being engaged with the orbiting wrap. In a state in which the orbiting scroll and the fixed scroll are concentric with each other, when a distance between the orbiting wrap and the fixed wrap is defined as an orbiting radius, there exists an offset section having an interval larger than the orbiting radius, between a side surface of the orbiting wrap and a side surface of the fixed wrap which faces the orbiting wrap. With such a configuration, even if the fixed scroll or the orbiting scroll is transformed due to thermal expansion, interference between the fixed wrap and the orbiting wrap at a portion having a large transformation amount may be prevented. This may prevent a frictional loss or abrasion between the fixed wrap and the orbiting wrap. Further, this may restrict or minimize a gap between the fixed wrap and the orbiting wrap at an opposite side to the suction chamber, resulting in enhanced compression efficiency.

There is disclosed a scroll compressor according to the present disclosure in which a discharge port is formed at a central portion thereof, and a pair of two compression chambers continuously moving toward the discharge port are formed, and a plurality of bypass portions are formed at each interval along a movement path of etch compression chamber in the both compression chambers, and compression gradients of the both compression chambers are formed to be different from each other, wherein when an interval between a bypass portion closest to the discharge port and another bypass portion adjacent to the bypass portion among the bypass portions of each compression chamber is defined as a first interval, respectively, a first interval of a second bypass portion belonging to a compression chamber having a relatively larger compression gradient is formed to be smaller than that of a first bypass portion belonging to the other compression chamber between the both compressor chambers.

In a gear pump, a gear chamber is defined in a housing hole of a housing. A pair of gears is housed in the gear chamber. The gears are rotatably supported at support holes of a pair of side plates via support shafts. As viewed in an axial direction of the support shafts during rotation of the gears, addendum circles of the gears displaced under a differential pressure between a low-pressure chamber and a high-pressure chamber form first contact points with respect to an inner peripheral surface that defines a housing hole. As viewed in the axial direction of the support shafts during rotation of the gears, the first contact points are covered with the side plates displaced under the differential pressure.

In a rotary compressor, a lower end plate cover is formed in a flat plate shape, a lower discharge chamber concave portion is formed in a lower end plate to overlap a lower discharge hole side of a lower discharge valve accommodation concave portion, and the lower discharge chamber concave portion is formed in a fan-like range between a diametrical line passing through a center of a sub-bearing unit and a midpoint of a line segment connecting a center of the lower discharge hole and a center of a lower rivet to each other and a diametrical line opened by a pitch angle 90° in a direction of the lower discharge hole about the center of the sub-bearing unit. At least a portion of a refrigerant path hole overlaps the lower discharge chamber concave portion and is disposed at a position communicating with the lower discharge chamber concave portion.

A compressor is provided and may include a shell, a hub, an insert, and at least one collar. The hub may be disposed within the shell and define an axis of rotation. The hub may include an axially extending aperture. The insert may be disposed within the aperture. The at least one collar may be disposed about the hub.

There are already known pump units comprising a drive shaft (2) and a rotatably arranged rotor (3) that is driven by the drive shaft (2), wherein the drive shaft (2) has an inclined sliding surface (4) on an end side, which permits the rotor (3) to move back and forth by its rotor axis (5) about a drive axis (6) of the drive shaft (2), wherein the drive shaft (2) has a first bearing section (18) facing towards the the rotor (3), and a second bearing section (19) facing away from the rotor (3). The first bearing section (18) of the drive shaft (2) is arranged in a first sliding bearing (20), and the second bearing section (19) is arranged in a second sliding bearing (21). The load-bearing capacity of the sliding bearing facing towards the rotor (3) is limited up to a predetermined working pressure in the pump unit. In the pump unit according to the invention, the load-bearing capacity of the sliding bearing (20) facing towards the rotor (3) is increased. According to the invention, the diameter of the first bearing section (18) of the drive shaft (2) and the first sliding bearing (20) is respectively larger than the diameter of the second bearing section (19) and the second sliding bearing (21).

A compressor includes: an annular cylinder; a rotation shaft which is rotated by the motor; a piston which revolves along an inner circumferential surface of the cylinder, and forms a cylinder chamber on the inside of the cylinder; a vane which protrudes to the inside of the cylinder chamber from a vane groove provided in the cylinder, and divides the cylinder chamber into an inlet chamber and a compression chamber by abutting against the piston; and an injection hole which injects a liquid refrigerant to the inside of the compression chamber. The center of the injection hole is disposed to be within a fan-like range of which a center angle is equal to or less than 40° toward a side opposite to a connection position between the compressor housing and the inlet unit from a center line of the vane groove in the circumferential direction of the rotation shaft.

A motor-operated compressor includes a casing having an inner space in which a driving motor, an orbiting scroll and a fixed scroll are accommodated, and a controller provided outside the casing. The casing includes an intake hole formed at a side adjacent to the controller and an exhaust hole formed at a side adjacent to the fixed scroll on the basis of the driving motor. The casing includes a communication passage formed between the casing and a stator of the driving motor, such that a refrigerant introduced into the inner space through the intake hole is introduced into the suction chamber through the driving motor. A back pressure space supporting the orbiting scroll is sealed by oil. The stator has teeth on its inner circumferential surface and protrusions on its outer circumferential surface, each protrusion being located within a width range of each tooth.