A roots pump includes a housing, a rotor chamber, a pair of rotary shafts, and a pair of rotors. The rotor chamber includes a rotor chamber peripheral surface facing a pair of distal end portions of each of the rotors. Each of the pair of the distal end portions includes: a pair of rotor peripheral surfaces facing the rotor chamber peripheral surface with a first radial clearance; and a distal end peripheral surface that is formed between the pair of the rotor peripheral surfaces in the rotational direction and faces the rotor chamber peripheral surface with a second radial clearance greater than the first radial clearance. A width of the rotor chamber peripheral surface facing the distal end peripheral surface in the rotational direction is greater than a sum of a pair of predetermined widths of the rotor chamber peripheral surface facing the pair of the rotor peripheral surfaces.

A scroll compressor including a bypass passage to guide compressed refrigerant from a compression chamber to a low pressure portion of the compressor; a valve that is inserted in a valve receiving portion and slides between first and second positions in which the bypass passage is respectively closed and opened; a ring-shaped seal between an outer peripheral surface of the valve and an inner peripheral surface of the valve receiving portion; and a seal groove formed in at least one of the outer peripheral surface of the valve and the inner peripheral surface of the valve receiving portion, the seal being inserted into the seal groove, wherein at least one of the outer peripheral surface of the valve, the inner peripheral surface of the valve receiving portion, and the inner peripheral surface of the seal groove has an inclined surface that is inclined in the opening/closing direction of the valve.

In one aspect, described is a rotor for a Wankel engine comprising two circumferentially spaced apart apex seals at each of the apex portions with each apex seal protruding axially from both end faces, and each apex seal having a first biasing member biasing the apex seal radially outwardly away from the peripheral face of the body, and a second biasing member biasing the apex seal axially outwardly away from a respective one of the end faces, the two apex seals of a same one of the apex portions being biased by the respective second biasing member in opposite axial directions from one another.

A rotary engine including a housing and housing head enclosing a combustion chamber, a piston including an output shaft and a piston disk within the housing and rotatable on a piston rotation axis, a quadrant within the housing and around the piston and rotatable on a quadrant rotation axis, wherein the quadrant rotation axis is acutely angled to the piston rotation axis, and a post surrounding a segment of the piston disk. The post pivots relative to the piston about a post-piston rotation axis that is normal to the face of the piston disk. The post pivots relative to the quadrant about a post-quadrant pivot axis that is perpendicular to the quadrant rotation axis. The post rotates about the quadrant rotation axis relative to the housing. Combusting fuel injected into the combustion chamber expands and pushes on the piston disk to rotate the output shaft about the piston rotation axis.

A scroll vacuum pump has an axially extending drive shaft with an eccentric shaft portion, such that rotation of the drive shaft imparts an orbiting motion to an orbiting scroll relative to a fixed scroll. An axial adjustment mechanism has a plurality of adjustment members angularly spaced around the drive shaft and extending through the pump housing towards the orbiting scroll, the plurality of adjustment members each being configured to provide an independently adjustable axial position of the orbiting scroll. A plurality of sealing means isolate the plurality of adjustment members from a pump chamber, the plurality of sealing means extending around each of the plurality of adjustment members and comprising at least one flexible portion such that one end of the sealing means may orbit relative to a fixed other end of the sealing means.

An outlet gasket which has a gasket structure made of a gasket material, for sealing off a first pressure outlet and a second pressure outlet of a pump, the gasket structure including: a first sealing stay which circumferentially encloses a first fluid passage of the outlet gasket, provided for the first pressure outlet, in a seal in an axial plan view onto the outlet gasket; and a second sealing stay which circumferentially encloses a second fluid passage of the outlet gasket, provided for the second pressure outlet and located laterally next to the first fluid passage, in a seal in the plan view, wherein the gasket structure forms the sealing stays contiguously as a unit, and/or the outlet gasket includes a support structure on which the sealing stays are arranged.

A rotor assembly has a sealing system for sealing at apexes or faces of the rotor. An apex seal or face seal comprises a compliant member that is configured such that the shape or orientation of the compliant member can change in use in response to a change in the speed of rotation of the rotor, a change in the pressurization across the compliant member, or a change in clearance between the sealing surface and a mounting element to which the compliant member is mounted, to deflect towards or away from the sealing surface.

The oil-free screw compressor includes: a screw rotor including a screw and a shaft; a bearing; a first shaft seal device disposed between the screw and the bearing, the first shaft seal device including: a first seal and a first communication section configured to communicate the bearing side with respect to between the shaft and the first seal, and an outer peripheral face of the first shaft seal device; a second shaft seal device disposed between the first shaft seal device and the bearing, the second shaft seal device including: a second seal and a second communication section configured to communicate the screw side with respect to between the shaft and the second seal, and an outer peripheral face of the second shaft seal device; and a first seal member including a seal between the first communication section and the second communication section. The casing includes an atmosphere communication section configured to communicate the first communication section and the second communication section with an atmosphere. A sectional area in the first communication section is larger than a sectional area between the seal of the first seal member and the shaft.

A scroll pump tip seal to be fitted to a tip face of a scroll wall of a first scroll of a scroll pump to seal between the tip face and a base plate of a second scroll of the scroll pump has a first end, a second end and a plurality of flexure formations. The flexure formations are at least partial discontinuities in the tip seal disposed at spaced apart intervals between the first and second ends of the tip to facilitate lateral flexure of the tip seal.

A scroll compressor includes a movable scroll and a fixed portion. The fixed portion has a first bearing surface. The movable scroll has a second bearing surface. The scroll compressor includes a back pressure chamber located between the movable scroll and the fixed portion. At least one of the movable scroll and the fixed portion is provided with a groove disposed on a periphery of the back pressure chamber. The scroll compressor further includes a sealing assembly at least partially installed in the groove. One end of the sealing assembly is in contact with a groove bottom surface in the groove, and another end of the sealing assembly is in contact with the first bearing surface or the second bearing surface. The sealing assembly includes a wear-resistant ring and an elastic ring. The elastic ring has at least one recess on a surface thereof.