A positive displacement device includes a first cylinder, a second cylinder disposed within the first cylinder, and a third cylinder disposed around the first cylinder. An interior surface of the first cylinder and an exterior surface of the second cylinder define an inner cavity. An exterior surface of the first cylinder and an interior surface of the third cylinder define an outer cavity. A partition between the interior surface of the first cylinder and the exterior surface of the second cylinder divides the inner cavity into inner regions, and another partition between the exterior surface of the first cylinder and the interior surface of the third cylinder divides the outer cavity into outer regions. The second cylinder and the third cylinder orbit with respect to the first cylinder to create alternating regions of high pressure and low pressure in the inner regions and the outer regions.

A negative pressure pump includes an electrically insulative casing an electrically conductive rotary shaft and an electrically conductive vane. The casing is formed in a tubular shape, an axial direction one end of which is closed off by a cap body. The rotary shaft is disposed in the casing, is mechanically and electrically connected to an earthed power source, and is rotated by power being transmitted from the power source. The vane is disposed in the casing, is supported at the rotary shaft to freely reciprocate in a direction orthogonal to the rotary shaft, and is electrically connected to the power source via the rotary shaft. The vane rotates integrally with the rotary shaft, and end portions of the vane slide over an inner wall face of the casing. The vane divides the interior of the casing into a plurality of spaces and generates negative pressure.

In the vane pump comprising the housing, the vane, and the cap, the sliding surface of the cap is configured as arc shape in the view from the rotational axis direction and the width toward the sliding direction of the cap is configured to be smaller than the width at the sliding angle field which is virtual area for contacting the inner surface of the pump room among the circumference including the arc shape of the sliding surface of the cap and to be bigger than the width at the high loading area where the load added to the sliding surface which is bigger than the predetermined value among the sliding angle field.

In the vane pump comprising the housing, the vane, and the cap, the sliding surface of the cap is configured as arc shape in the view from the rotational axis direction and the width toward the sliding direction of the cap is configured to be smaller than the width at the sliding angle field which is virtual area for contacting the inner surface of the pump room among the circumference including the arc shape of the sliding surface of the cap and to be bigger than the width at the high loading area where the load added to the sliding surface which is bigger than the predetermined value among the sliding angle field.

A sealing arrangement between a rotating plane surface on a rotor and a machine housing prevents flow of process fluid between an internal volume and an external volume of the machine housing. The sealing arrangement includes a piston arrangement, and a sealing bearing ring between the piston arrangement and the rotating plane surface. A fluid supply line supplies pressurized lubrication fluid through the machine housing to a piston cavity, wherein the piston arrangement further includes piston fluid channels and the bearing sealing ring includes lubrication conduits through the bearing sealing ring, corresponding with the piston fluid channels. The pressurized lubrication fluid is arranged for moving the piston arrangement against the sealing bearing ring and thus moving the sealing bearing ring against the sealing surface thus forming a sealing arrangement.

A sealing arrangement between a rotating plane surface on a rotor and a machine housing prevents flow of process fluid between an internal volume and an external volume of the machine housing. The sealing arrangement includes a piston arrangement, and a sealing bearing ring between the piston arrangement and the rotating plane surface. A fluid supply line supplies pressurized lubrication fluid through the machine housing to a piston cavity, wherein the piston arrangement further includes piston fluid channels and the bearing sealing ring includes lubrication conduits through the bearing sealing ring, corresponding with the piston fluid channels. The pressurized lubrication fluid is arranged for moving the piston arrangement against the sealing bearing ring and thus moving the sealing bearing ring against the sealing surface thus forming a sealing arrangement.

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.

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.

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.