The invention reduces a pressure or thermal effect while reducing the mass of a screw rotor. There is provided a screw rotor having a helical tooth on an outer periphery, the helical tooth extending by a predetermined length in an axial direction, in which a radial cross section of the screw rotor includes a lobe portion having a predetermined thickness in a direction toward an axis and forming the helical tooth, and a hollow portion extending from an axial side inner surface of the lobe portion toward an axial side, and the predetermined thickness of the lobe portion differs between a high load side on the outer periphery of the screw rotor and a low load side on the outer periphery.

Rotors formed by an additive manufacturing process are presented. In one example, a method of making a rotor is presented including defining a printing order for the application of a first material, and creating a plurality of lobes arranged helically about a central opening or a shaft by adding a first material in the printing order, wherein each of the plurality of lobes defines an outer surface.

A compressor includes a first scroll and a second scroll engaged with the first scroll for performing an orbiting motion relative to the first scroll to form a compression chamber along with the first scroll. A stator is disposed at one side of the second scroll and includes a stator core. A rotor is rotatably disposed inside the stator core, and includes a rotor core. A rotary shaft has one end portion eccentrically coupled to the second scroll and the other end portion coupled to the rotor core. The rotor core is formed with at least one space portion axially recessed into the rotor core.

One example of a gerotor pump includes an inner rotor comprising multiple teeth, the inner rotor configured to rotate about a first longitudinal gerotor pump axis. The gerotor pump also includes a hollow outer rotor including an outer surface and an inner surface having substantially identical contours, the inner surface configured to engage with the multiple teeth and to rotate about a second longitudinal gerotor pump axis. The pump includes a pump housing within which the inner rotor and the outer rotor are disposed, wherein the outer surface of the outer rotor defines gaps between the pump housing and the outer rotor.

Sealing in rotary positive displacement machines based on trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator is described. Seals can be mounted on the rotor, the stator, or both. 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 advantages with respect to sealing in the rotary machine. In multi-stage embodiments, the rotor-stator geometry remains substantially constant or 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.

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.

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 scroll compressor includes a motor portion fixed in an inner space of a casing, a compression portion fixed to the inner space of the casing at one side of the motor portion in an axial direction, a rotation shaft to transmit a driving force from the motor portion to the compression portion, and a flow path guide provided in a discharge space between the motor portion and the compression portion and provided with a guide outlet communicating with the discharge space and opened in a direction toward the rotation shaft. Therefore, most of refrigerant discharged to the discharge space through the flow path guide is moved toward an air gap to enhance an oil separation effect, and thus a normal operation point of the air conditioner can be accelerated.

Provided is a scroll compressor. The scroll compressor may be provided with at least one refrigerant accommodating groove recessed to a preset depth in at least one from a side surface of a fixed wrap constituting a compression chamber and a side surface of an orbiting wrap. Thus, a volume of the compression chamber in a discharge area may be increased in correspondence with a volume of the at least one refrigerant accommodating groove, and a space into which liquid refrigerant, etc. may escape may be ensured to resolve excessive compression in the compression chamber. Then, a stress exerted on the fixed wrap is reduced, and a damage to the fixed wrap due to pressure in the compression chamber may be suppressed.