Provided is a gasket (30), which is used in a motor-driven compressor including an inverter housing, including a flat core of metal (31) and an elastic foamed material (32) so disposed as to cover both surfaces of the core (31), and the gasket (30) has embossed recesses and projections (33) with predetermined shapes. It is possible to enhance sealing performance to seal the inverter housing by using this gasket (30). A motor-driven compressor using this gasket (30) enhances vibration prevention.

A gas compressor includes a block part inside which a cylinder chamber is formed; a rotor rotatably housed in the cylinder chamber; and vanes provided on an outer circumferential portion of the rotor. The block part has a pressure supply part configured to supply pressure to backpressure spaces behind the vanes. This pressure supply part has an intermediate-pressure supply part which communicates with each backpressure space from an intake cycle to a compression cycle in the compression chamber, a first high-pressure supply part which communicates with the backpressure space from the compression cycle to a discharge cycle in the compression chamber, and a second high-pressure supply part which is formed between the intermediate-pressure supply part and the first high-pressure supply part independently of the first high-pressure supply part and which communicates with the backpressure space in a middle of the compression cycle in the compression chamber.

A gas compressor includes a block part inside which a cylinder chamber is formed; a rotor rotatably housed in the cylinder chamber; and vanes provided on an outer circumferential portion of the rotor. The block part has a pressure supply part configured to supply pressure to backpressure spaces behind the vanes. This pressure supply part has an intermediate-pressure supply part which communicates with each backpressure space from an intake cycle to a compression cycle in the compression chamber, a first high-pressure supply part which communicates with the backpressure space from the compression cycle to a discharge cycle in the compression chamber, and a second high-pressure supply part which is formed between the intermediate-pressure supply part and the first high-pressure supply part independently of the first high-pressure supply part and which communicates with the backpressure space in a middle of the compression cycle in the compression chamber.

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

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

The control section controls the electric motor to be driven such that the number of revolutions becomes equal to the target number of revolutions. If the control section sets the target number of revolutions to a number of revolutions of the electric motor requested by another control section, the control section changes the number of revolutions of the electric motor at an increase rate lower than or equal to the upper limit value of the increase rate or at a decrease rate lower than or equal to the upper limit value of the decrease rate. If the control section sets the target number of revolutions to a number-of-revolutions limit value, which is determined based on the voltage of a vehicle battery, the control section is able to decrease the number of revolutions of the electric motor at a decrease rate exceeding the upper limit value.

An electric compressor includes a cylindrical housing, a rotary shaft accommodated and rotatably supported in the housing, a compression portion compressing refrigerant gas by rotation of the rotary shaft, a stator accommodated in the housing and fixed to the housing, a rotor accommodated in the housing and fixed on the rotary shaft, and a plurality of guide members disposed between the inner peripheral surface of the housing and an outer peripheral surface of a stator core of the stator. A plurality of recesses is recessed in a radial direction of the rotary shaft on the outer peripheral surface of the stator core of the stator and spaced apart from each other in a peripheral direction of the rotary shaft. The guide members are fitted in the respective recesses with a part of the guide members projecting radially outward beyond the outer peripheral surface of the stator core.

An electric compressor includes a housing, a rotary shaft, a compression portion compressing refrigerant gas, a stator, a rotor, and guide members disposed between the housing and the stator and spaced away from each other in a peripheral direction of the rotary shaft. The guide members include an engagement portion projecting in a radially outward direction of the rotary shaft. The housing has in an inner peripheral surface thereof an engagement hole to receive the engagement portion. An electric compressor includes a housing, a rotary shaft, a compression portion compressing refrigerant gas, a stator, a rotor, and guide members disposed between the housing and the stator and spaced away from each other in a peripheral direction of the rotary shaft. An engagement projection is formed projecting radially inwardly from the inner peripheral surface of the housing. The guide members include an engagement hole to receive the engagement projection.

A screw compressor is provided which can reduce the pressure loss in a suction flow passage. A casing 12 of the screw compressor includes a bore 21 that accommodates a lobed portion 13A of a male rotor 11A and a lobed portion 13B of a female rotor 11B therein such that working chambers are formed in lobe grooves of the lobed portions, a suction port 22 located on an outer side in a rotor radial direction, and a suction flow passage 23 that communicates in a rotor axial direction with working chambers that are in a suction stroke. The suction flow passage 23 includes a male rotor side suction flow passage 26A located on an male rotor 11A side and besides on a downstream side with respect to a virtual plane C, and a female rotor side suction flow passage 26B located on an female rotor 11B side and besides on the downstream side with respect to the virtual plane C. The male rotor side suction flow passage 26A is formed such that a flow passage wall 27A on the outer side in the rotor radial direction is located at a position that is the same as that of a wall of the bore 21 as viewed in the rotor axial direction at least within a range of one half of an axial pitch P1 of the lobed portion 13A of the male rotor 11A from a suction side end surface of the lobed portion 13A in the rotor axial direction.

A compressor may include a first scroll member, a second scroll member and a drive shaft. The first scroll member may include a first end plate defining a first discharge port and a first spiral wrap extending from the first end plate. The second scroll member may include a second end plate defining a first variable volume ratio port and a second spiral wrap extending from the second end plate and meshingly engaged with the first spiral wrap and forming compression pockets. The variable volume ratio port may be located radially outward relative to the first discharge port and in communication with a first compression pocket. The drive shaft may be engaged with the second scroll member and driving orbital displacement of the second scroll member relative to the first scroll member.