A screw rotor which is hollow has improved performance against heat, pressure, rust, and the like. A screw rotor includes a screw portion of which an outer periphery has teeth and grooves having a helical shape and extending by a predetermined length in an axial direction. A radial cross section of at least a part of the screw portion includes a cross section of an outer surface portion forming the teeth and the grooves, a cross section of an axial center portion, a cross section of a support portion that connects an axial center side of the outer surface portion and an outer diameter side of the axial center portion, and a cross section of a hollow portion formed by the support portions adjacent to each other in a rotational direction and an axial center side inner surface of a tooth bottom or a tooth tip. In at least the radial cross section of the screw portion, different members are continuously joined as an integral structure in a cross section of at least one of the axial center portion and the support portion and the outer surface portion.

It is assumed that a distance between a center portion of fixed scroll end plate and an outer peripheral portion at a distal end of fixed spiral wrap of fixed scroll is Ds, and that a distance between a center portion of orbiting scroll end plate and a portion included in a bottom face of an orbiting spiral wrap of orbiting scroll and facing the outer peripheral portion at the distal end of the fixed spiral wrap of the fixed scroll is Do. Further, assuming that an orbiting radius of orbiting scroll is ε, the orbiting radius being a distance between a center of eccentric shaft and a center of driving shaft, a relationship Ds+ε≤Do is satisfied.

The scroll-type compressor comprises a fixed scroll and an orbiting scroll engaged with each other; a back pressure control valve 50 inserted from the large-diameter side of the stepped-shaped pressure release passage L4 which communicates between a suction chamber H1 and a back pressure chamber H3 which applies a back pressure for pressing the orbiting scroll against the fixed scroll. The scroll-type compressor further comprises an O-ring 60 fitted in a circumferential groove 53a formed in the outer peripheral surface of the valve 50, and a ring member 61 press-fitted into the large-diameter side of the pressure release passage L4, and holds the valve 50 between the ring member 61 and the stepped portion. Then, the compressive stress is unlikely to be applied to the valve 50, and the deformation of the valve 50 is reduced to prevent the reduction in the control accuracy of the back pressure.

This disclosure relates to pumps and, more particularly, to progressive cavity pumps.

A rotary internal combustion engine that has a housing, main rotors with an external cylindrical surface with rigidly fixed gear wheels and blades in the form of gear ledges (protrusions), as well as additional rotors with an external cylindrical surface with rigidly fixed gear wheels and recesses corresponding to the size of the blades on the main rotors. Additionally, the engine includes a unit for preparing and igniting the working mixture and a unit for discharging exhaust gases. Moreover, the circumference values of the main and additional rotors do not match, and are multiples of the length L1 between the nearest points of tangency (physical contact) of the center of the surface of the gear ledge with the housing.

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).

A vane pump including: a housing having a pump chamber; a rotor having a cylindrical peripheral wall portion accommodated in the pump chamber and having a pair of vane holding grooves facing each other in a diameter direction, and an oil chamber defined inside the peripheral wall portion to store lubricating oil; and a vane that is held in the pair of vane holding grooves and moves across the oil chamber in the diameter direction, is provided. At least one of an inner surface of the housing and an end face of the peripheral wall portion, which together with the inner surface defines a sliding interface, has an oil groove for the lubricating oil.

A pin-ring mechanism that transmits driving force to cause a driving-side scroll member and a driven-side scroll member to perform rotational movement in a same direction at a same angular velocity is provided. A driving-side end plate includes a ring member installation hole into which a ring member is inserted and installed. The ring member installation hole includes a non-wall-side hole part and a wall-side hole part. The non-wall-side hole part is formed from a non-wall-side surface and has a diameter corresponding to an outer diameter of the ring member. The wall-side hole part is formed from a wall-side surface and has a diameter smaller than the outer diameter of the ring member.

Rotary positive displacement machines with 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 multi-stage embodiments, the rotor-stator geometry remains substantially constant along the axis of the rotary machine. In other multi-stage embodiments, the rotor-stator geometry varies along the axis of the rotary machine.

The present invention refers to a progressive cavity pump developed for tintometric dosing machines. The proposal set out in the present invention is to make precision dosages through pumping by just one stator and rotor stage. The PCP proposal enhances the traditional constructive arrangement for tintometric application. The object makes precision dosages through pumping by just one stator and rotor stage, reducing the length of the pump, facilitating the manufacture of its components and requiring less robustness of the transmission components and of the drive motor. Therefore, the present invention has a simplified transmission system, uses special geometry for fastening the stator, optimizes the bearing of the drive shaft and its sealing element, reduces the dimensions of the components and uses a low torque motor.