A liquid pump of the present disclosure includes a container, a shaft, a bearing, a pump mechanism, a storage space, and a liquid supply passage. The shaft is disposed in the container. The bearing supports the shaft. The pump mechanism pumps a liquid by rotation of the shaft. The storage space is defined in the container at a position outside the pump mechanism. The storage space stores the liquid to be taken into the pump mechanism or the liquid to be discharged to outside of the container after being expelled from the pump mechanism. The liquid supply passage is a flow path including an inlet open to the storage space and supplying the liquid stored in the storage space to the bearing.

A compressor may include a compression mechanism and a shell assembly. The shell assembly may include first and second snap rings, a body, and first and second caps cooperating with the body to enclose the compression mechanism therein. The body may include first and second ends and an inner surface extending between both ends. The first cap may be received within the first end and may include a first side wall having a first groove. The second cap may be received within the second end and may include a second side wall having a second groove. The first snap ring may be disposed within the first groove and may engage the first end to restrict removal of the first cap from the body. The second snap ring may be disposed within the second groove and may engage the second end to restrict removal of the second cap from the body.

Combining at least one centrifugal compression stage and at least one positive displacement compression stage in an integrally geared compressor to allow for different types of compression based on a temperature or a volume of gas to be compressed by the integrally geared compressor.

A brushless DC compressor comprising a casing, a brushless DC motor, a compression device, and a driving mechanism. The casing has a left room, a right room adjacent the left room, and a lower room. The brushless DC motor is disposed in the left room, and the compression device is disposed in the right room. The driving mechanism is disposed in the lower room, including a driving gear engaging a rotor of the brushless DC motor, a driven gear engaging a hollow shaft of the compression device and driven by the driving gear; whereby refrigerant flows into a compression space of the compression device, rotating the rotor by the stator and driving the driving gear, the driven gear, then the compression device; then being discharged from a refrigerant discharge hole and an axial groove, to form a brushless DC compressor with stronger torque and greater compression efficiency.

The invention relates to a method for controlling a rotary screw compressor, having at least a first and a second air-end, wherein both air-ends are driven separately from one another and speed controlled. According to the invention, the following steps are carried out: detection of a volume flow taken at the outlet of the second air-end; adjustment of the rotational speed of both air-ends, when the removed volume flow fluctuates in a range between a maximum value and a minimum value; opening of a pressure-relief valve, if the volume flow falls below the minimum value; and reduction of the rotational speed of at least the first air-end to a predetermined idling speed (V1.sub.L) to reduce the volumetric flow delivered by the first to the second air-end.

A scroll type compressor includes an orbiting scroll including an orbiting wrap and a fixed scroll including a fixed wrap, in which first and second oil channels are respectively configured to supply oil to inner and outer oil channels formed by the orbiting wrap and the fixed wrap. Thus, the scroll type compressor has an oil channel structure that allows oil feeding into to the scrolls.

The invention relates to a screw pump having two screws, in which screw pump each screw has a first thread and a second thread. The threads extend in each case from a suction side to a delivery side. The threads are in engagement with one another, with the result that the threads are divided into a plurality of working chambers, the volume of which decreases from the suction side to the delivery side. According to the invention, the threads have two thread turns. Moreover, the invention relates to a screw for a pump of this type. On account of the uniform distribution of mass of the two-turn threads, the pump can be operated at a high rotational speed, with the result that the throughput of the pump is increased.

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 cylindrical rotor inside of the cylindrical stator, wherein the cylindrical rotor has a screw thread with an opposite direction relating to the stator screw thread, wherein the rotor has a curvilinear external surface shape and a stator having an internal semicircular surface shape wherein rotor external surface shape and the stator has an internal surface shape having rounded shapes without rectangular edges to obtain high speed performance with reduced vortices, wherein a gap between the internal surface of the stator and the external surface of the rotor is 0.1-0.2 millimeters and an unloading thrust bearing attached to the rotor shaft positioned between intake thrust bearing and the intake end of the rotor and a cavity in the unloading thrust bearing configured to receive production fluid from the discharge end of the rotor.

A compressor includes a compression mechanism and a driveshaft that drives the compression mechanism. The driveshaft may include a first axially extending passage, a second axially extending passage, and a lubricant distribution passage. The first and second axially extending passages may be radially offset from each other and may intersect each other at an overlap region. The first and second axially extending passages are in fluid communication with each other at the overlap region. The lubricant distribution passage may extend from the first axially extending passage through an outer diametrical surface of the driveshaft. The lubricant distribution passage may be disposed at a first axial distance from a first axial end of the driveshaft. A first axial end of the overlap region may be disposed at a second axial distance from the first axial end of the driveshaft. The first axial distance may be greater than the second axial distance.