A scroll compressor includes a fixed scroll fixed inside a housing, an orbiting scroll configured to orbit engaged with the fixed scroll, a rotary shaft configured to allow the orbiting scroll to orbit by supporting the orbiting scroll with an eccentric shaft eccentric from a main shaft, and a slide bush portion installed between a bearing of the orbiting scroll and the eccentric shaft and according to a rotational speed of the rotary shaft, configured to change a pressing force of the orbiting scroll applied to the fixed scroll by allowing an eccentricity to be changed by a gas load applied to the orbiting scroll.

A rotary piston compressor (1) for a system for temperature conditioning comprises a rotor (19) mounted in a housing (21), wherein the rotary piston compressor (1) is designed in such a way that the rotor (19) rotates in a first direction in a first operating state and rotates in a second direction opposite to the first direction in a second operating state, and wherein, in the first operating state, a first compressor connection (3) is designed to supply a heat transfer medium (17), and a second compressor connection (5) is designed to discharge the compressed heat transfer medium (17), and wherein, in the second operating state, the second compressor connection (5) is designed to supply the heat transfer medium (17), and the first compressor connection (3) is designed to discharge the compressed heat transfer medium (17).

Rotary positive displacement machines based on trochoidal geometry, that comprise a helical rotor that undergoes planetary motion within a helical stator are described. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some embodiments, the geometry is offset in a manner that provides structural and/or operational advantages in the rotary machine.

Rotary positive displacement machines based on trochoidal geometry that includes a helical rotor that undergoes planetary motion relative to a helical stator are described. The rotor can have a hypotrochoidal-based cross-sectional shape, with the corresponding stator cavity cross-sectional shape being the outer envelope of the rotor cross-sectional shape as it undergoes planetary motion, or the stator cavity can have an epitrochoidal-based cross-sectional shape with the corresponding rotor cross-sectional shape being the inner envelope of the stator cross-sectional shape as it undergoes planetary motion. Such machines can be configured so that the stator axis is spaced from the rotor axis, the rotor is configured to spin about its axis and the stator is configured to spin about its axis, and/or the rotor and the stator are held at a fixed eccentricity so that the rotor undergoes planetary motion relative to the stator, but does not orbit.

A rotor for a mud motor includes a core having a first outer shape, and a shell positioned around the core, the shell having a second outer shape that is different from the first outer shape, the second outer shape defining one or more lobes and one or more cavities that are configured to engage a bore of a stator during rotation of the rotor relative to the stator. A thickness of the shell varies as proceeding around the core, from a non-zero minimum thickness to a maximum thickness.

A compressor includes a rotary shaft, a front rotor including a front rotor surface, an intermediate wall portion including a first wall surface opposed to the front rotor surface in an axial direction, and a vane that is inserted into a vane groove formed in the intermediate wall portion and is moved in the axial direction with rotation of the front rotor. The vane includes a first vane end that is an end in the axial direction and contacts the front rotor surface. The first vane end is curved so as to be convex toward the front rotor surface and extends in the direction perpendicular to the axial direction. The front rotor surface includes a front curving surface curved in the axial direction so as to be displaced in the axial direction in accordance with its angular position.

A dry-running vane gas pump includes a pump housing which forms a pump chamber, a pump rotor with at least one displaceable slide element which pump rotor is rotatably supported in the pump chamber, at least one fluid inlet opening associated with the pump chamber, a first fluid outlet opening associated with the pump chamber, a second fluid outlet opening associated with the pump chamber, and a non-return valve which closes the first fluid outlet opening. The second fluid outlet opening is permanently open. The first fluid outlet opening is arranged before the second fluid outlet opening in a direction of rotation of the pump rotor.

A supercharger having twisted meshing rotors sealingly contained within a housing having an inlet port to admit air into the meshing rotors and an outlet port to expel air from the meshing rotors, the rotors having mesh points where the rotors contact one another and spaces between their mesh points to accept air from the inlet port and propel it to the outlet port as the rotors are rotated and the mesh points travel axially, the housing, inlet and rotors defining an angle known as the seal transfer angle which is greater than or equal to zero degrees when the inlet port is closed and the volume of air between rotors is sealed and has no leakage path. In the described supercharger the housing, rotors and inlet port are configured to have a negative seal transfer angle of, e.g., −10 to −40 degrees or more, up to the maximum available, and to provide a leakage path for an angular portion of the rotors' rotation, improving high end performance without degrading low end performance.

A scroll compressor includes a casing; a drive motor; a rotary shaft; a fixed scroll including a fixed wrap; and an orbiting scroll eccentrically coupled to rotary shaft and including an orbiting wrap configured to engage with the fixed wrap. At least one of the fixed wrap or the orbiting wrap defines an offset section that is defined between the fixed wrap and the orbiting wrap and that is greater than an orbital radius corresponding to a distance between the fixed wrap and the orbiting wrap in a state in which a center of the fixed scroll is aligned to a center of the orbiting scroll. The offset section is disposed at a contact portion between the fixed wrap and the orbiting wrap. The contact portion has a maximum length based on a rotation angle of the rotary shaft being within a pre-set range with respect to a reference point.

Each of recesses in outer circumferential surfaces of rotors includes: a leading-side area extending forward from a longitudinal center of an associated one of the outer circumferential surfaces in a rotation direction of the rotor, and a trailing-side area continuous with the leading-side area, and extending rearward from the longitudinal center in the rotation direction. From the longitudinal center of the associated one of the outer circumferential surfaces in the rotation direction, forward extension of the leading-side area is longer than rearward extension of the trailing-side area. The leading-side area has a larger volume than the trailing-side area.