Pressure changing devices and methods of making and using the same are disclosed. One pressure changing device includes an elliptic cylinder and a piston that has an external surface with a trochoid cross-section. Another pressure changing device includes a piston and a rotating cylinder that has an internal surface with a trochoid cross-section. Another pressure changing device includes two fixed axes, one for rotation of one component and another for orbiting or oscillation of the other component. The devices and methods include stacked pressure changing devices with one or more common shafts. The pressure changing device may be easier and less expensive to manufacture and repair than prior pressure changing devices of the same or similar functionality, and can provide efficient gap sealing in a high-pressure expansion part of a compression or expansion cycle.

A vacuum device, in particular to a vacuum pump, includes a reservoir for an operating medium; an outlet connector arranged at or in the reservoir; and a selection device that selectively closes or opens the outlet connector or an outlet line, which is connected via the outlet connector to the reservoir, in dependence on whether the operating medium or water is present at the outlet connector.

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.

This scroll compressor includes a scroll compression unit including a first fixed scroll including a first fixed base plate and a first fixed spiral wrap, an orbiting scroll arrangement (7) including a first orbiting spiral wrap (14), the first fixed spiral wrap and the first orbiting spiral wrap (14) forming a plurality of first compression chambers. The scroll compressor further includes a refrigerant suction part suitable for supplying the scroll compression unit with refrigerant to be compressed. The orbiting scroll arrangement (7) further includes a first orbiting guiding portion (21) extending from an outer end portion of the first orbiting spiral wrap (14) and configured to guide, in use, at least a part of the refrigerant supplied to the scroll compression unit towards the first compression chambers.

A multi-stage vacuum pump may include a sealing arrangement for sealing between the stator components of the pump. The end seals of the arrangement comprise an annular portion for sealing between end stator components and shell components and axial portions which extend from the annular portion and together with separate axial seals seal between the shell components.

Provided is a tip seal that makes it possible to improve the durability of a tip seal installed on the tooth tip of a wall even when a continuously inclined section is provided to the wall. The tip seal is provided with: a tip seal inclined section (7A) installed in a groove section of a wall in which the height changes continuously in a spiral direction; and a tip seal flat section (7B) that is installed in a groove section of the wall in which the height is fixed in the spiral direction and that is adjacent to the tip seal inclined section (7A). A recess (8) is formed at a position away from the adjacent area between the tip seal inclined section (7A) and the tip seal flat section (7B).

A compressor includes: a casing with an inner wall defining a compression chamber, an inlet leading into the compression chamber, and an outlet leading out of the compression chamber; a rotor rotatably coupled to the casing for rotation relative to the casing; and a gate coupled to the casing for movement relative to the casing. The gate may be pivotally, or translationally coupled to the casing. A hydrostatic bearing may be disposed between the gate and casing. A plurality of compressors may be mechanically linked together such that their compression cycles are out of phase.

A rotary-vane mechanism can include a rotor and a casing, wherein the rotor includes a drive shaft and one or more vanes. The casing can include a quasi-cylindrical tubular shell or a quasi-spherical shell, and can provide walls that support the drive shaft. The rotor can be mounted within the casing. The drive shaft can extend outward from the casing, wherein the drive shaft touches the inner surface of the casing in one or more contact locations, with the contact location(s) provided by a sealing plate. The casing can include intake ports, exhaust ports, ports for an ignition mechanism, wherein the intake ports are provided with one-way valves. The drive shaft can include one or more guide slots, which can penetrate through the drive shaft wherein the vane(s) is located inside the guide slot(s), and edges of the vane(s) can constantly touch the inner surface of the casing during a rotor rotation of the rotor. Each vane can possess a rectangular shape or a discoid shape, and the sealing plate or a sealing ring can be located along an edge of the vane(s). The rotor and the casing can form isolated spaces inside the rotary-vane mechanism and during the rotor rotation can provide three work strokes for an engine, and two strokes for a compressor.

Provided is a sliding component capable of stably reducing the frictional resistance of a sliding surface entailing eccentric rotation. A sliding component has an annular shape with high-pressure and low-pressure fluids facing inside and outside of the sliding component and has a sliding surface relatively sliding with eccentric rotation. The sliding surface is provided with a plurality of high-pressure grooves open to a space in which the high-pressure fluid exists and a plurality of low-pressure grooves open to a space in which the low-pressure fluid exists. The high-pressure and low-pressure grooves are arranged in a circumferential direction.

In a scroll compressor (1) provided with a fixed scroll (3) and an orbiting scroll (5), an inclined portion is provided in which the inter-facing surface distance (L) between an end plate (3a) and an end plate (5a) that face each other decreases continuously from the outer peripheral side towards the inner peripheral side. The inclined portion is configured from wall inclined portions (3b1, 5b1) in which the height of a wall (3b, 5b) decreases continuously from the outer peripheral side towards the inner peripheral side, and end plate inclined portions (3a1, 5a1) in which a tooth bottom surface is inclined in accordance with the incline of the wall inclined portions (3b1, 5b1). The inclined portion is provided across a range of no less than 180° around the center of the spiral.