A scroll compressor is provided that may include a casing including a rotational shaft, a cover fixed inside of the casing to partition the inside of the casing into a suction space and a discharge space, a first scroll revolved by rotation of the rotational shaft, a second scroll disposed on or at one side of the first scroll to define a compression chamber together with the first scroll, the second scroll including a discharge, through which a refrigerant pressed in the compression chamber may be discharged, a switching device movably disposed on or at one side of the discharge to selectively open and close the discharge, a back pressure portion including a moving guide that accommodates at least a portion of the switching device, and a top surface that covers one side of the switching device; and an adhesion preventer that reduces a contact area between the switching device and at least a portion of the back pressure portion.

A scroll-type fluid machine reduces intrusion of abrasion powders, generated by sliding of a conductor causing an orbiting scroll side and a fixed scroll side to be conducted, into a compression chamber, and improves reliability of a compressor. The scroll-type machine includes a casing, a fixed scroll having a flange surface attached to the casing, and a wrap portion provided at an end plate, an orbiting scroll having a wrap portion provided at the end plate, and provided in an opposed relationship with the fixed scroll, a drive shaft connected through a crank portion to the orbiting scroll, an orbiting bearing, a face seal portion arranged between the orbiting scroll and the fixed scroll, a cooling fan, and an orbiting scroll side conductive brush.

A compressor may include a shell, first and second scroll members, a partition plate and a bypass valve member. The shell defines a discharge-pressure region and a suction-pressure region. The first scroll member is disposed within the shell and may include a first end plate having a discharge passage, and first and second bypass passages extending through the first end plate. The partition plate is disposed within the shell and separates the discharge-pressure region from the suction-pressure region and includes an opening in communication with the discharge-pressure region. The bypass valve member is movable between a first position restricting fluid flow through at least one of the first and second bypass passages and the opening and a second position in allowing fluid flow through the at least one of the first and second bypass passages and the opening.

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.

A scroll compressor is provided that may include a first scroll, a second scroll that defines a plurality of compression chambers together with the first scroll, the second scroll having a discharge hole that communicates with a compression chamber among the plurality of compression chambers, a back pressure plate that defines a back pressure chamber to accommodate a refrigerant discharged from the discharge hole, a floating plate to define the back pressure chamber, and a sealing member to prevent the refrigerant from flowing between a first surface, which may be a sliding surface of the floating plate, and a second surface, which may face the first surface, of the back pressure plate. The sealing member may include a seal cover that contacts the other one of the first and second surfaces, and a seal, a portion of which may be accommodated in the seal cover. The seal cover may have a friction coefficient less than a friction coefficient of the seal.

The oil-free screw compressor includes: a casing having a rotor chamber; a bearing supporting rotary shafts of screw rotors; a shaft seal device with an oil seal portion and an air seal portion; a ventilation gap positioned between the oil seal portion and the air seal portion; and an atmosphere open passage communicating an atmosphere side of the casing with the ventilation gap communicate. A most narrowed portion, an air seal portion, and oil seal portions are set such that the followings is established:

(La/Sa.sup.2.5)/(Lh/Sh.sup.2.5)>|P2|/ΔPb La: effective shaft seal length Sh: effective open cross-sectional area (most narrowed portion of atmosphere open passage) Lh: effective narrowed length (most narrowed portion of atmosphere open passage) Sa: shaft seal cross-sectional area |P2|: negative pressure in rotor chamber during unloading operation ΔPb: minimum differential pressure in the oil seal portion during the unloading operation

A scroll compressor according to the present invention includes a partition plate that partitions a sealed container into a high-pressure space and a low-pressure space, a fixed scroll adjacent to the partition plate, a orbiting scroll, a rotation restrictor, and a main bearing. The sealed scroll compressor further includes a pillar member having a lower end portion secured in a bearing-side engagement portion provided in the main bearing, and an upper end portion inserted in a scroll-side engagement portion provided in the fixed scroll. The axial distance from the upper end portion of the pillar member to the partition plate is smaller than the length by which the pillar member and the bearing-side engagement portion are coupled together.

A motor-driven compressor is installed in a fuel cell vehicle to supply air to a fuel cell. The motor driven compressor includes a rotation shaft, an electric motor, a compression unit that compresses air, a housing that includes a motor chamber and a compression chamber, and a seal member that restricts a flow of a fluid between the motor chamber and the compression chamber. The housing includes an inlet and an outlet. The inlet draws, into the motor chamber, the air-conditioning refrigerant that has passed through the evaporator but has not reached the air-conditioning compressor as a low-temperature refrigerant. The outlet discharges the low-temperature refrigerant, which is drawn from the inlet into the motor chamber, out of the motor chamber.

A scroll compressor is provided in which a center of a back pressure chamber is eccentrically disposed relative to a center of a fixed scroll. For example, the center of the back pressure chamber may be moved towards a center of an orbiting scroll at a time of discharge, thereby preventing displacement of the fixed scroll and ensuring stability in orbital movement of the orbiting scroll.

A screw compressor includes a screw rotor, a casing, and a delivery side shaft sealing unit. The delivery side shaft sealing unit includes an annular groove, a seal ring, and a shaft sealing fluid supply passage. Pressure of the fluid that is supplied to the one side, in the axial direction, of the seal ring via the shaft sealing fluid supply passage is set higher than pressure that acts on a first side surface, in an axial direction with respect to a first side wall surface of the annular groove, of the seal ring.