A motor includes a housing, a shaft, a bearing, a bearing plate, and a seal. The housing includes first and second housing components directly engaging one another along a housing interface. The housing at least in part defines a sealed chamber. The shaft is at least in part received in the chamber. The bearing rotatably supports the shaft. The bearing plate is enclosed within the housing. The bearing plate supports the bearing within the housing. The seal is disposed along the housing interface. The bearing plate is spaced inwardly from the housing interface and the seal.

A rotor-chamber wall of a motor-driven Roots pump has a suction port and a discharge port. The side on which the discharge port is located with respect to a plane that includes both the rotational axis of a drive shaft and the rotational axis of a driven shaft is a first side. A first partition wall defines a gear chamber and has a first recess on the first side. A second partition wall defines the gear chamber and has a second recess. The first partition wall has a first oil supply passage that is configured to supply oil from the first recess to a first seal accommodating recess. The second partition wall has a second and a third oil supply passages. The second and the third oil supply passages are configured to supply oil from the second recess to a second and a third seal accommodating recesses, respectively.

A piston is arranged to move in a cylinder to define a variable volume chamber, and can expand in two directions under the influence of pressure in the variable volume chamber to provide sealing against the cylinder. The piston can comprise a primary foot and a secondary foot arranged to move relative to each other in a first direction. The primary foot and the secondary foot can each comprise plural segments arranged to move relative to each other in a second direction. The piston may be suitable for use in an inner rotor, where it forms the end of a projection of the inner rotor and fully exits and reenters the cylinders.

In a conventional screw compressor, two mating rotors which resemble screws are assembled in parallel with each other within a housing. These rotors are very costly to manufacture, and it is very difficult to extract all of the gas that has been compressed between the lobes of the rotor screws. This invention eliminates the twist of the lobes around the rotor of a conventional screw compressor. In this invention, the lobes are manufactured in line with the axis of the rotor (axially). As a result, the costs of manufacturing the rotors are reduced dramatically, and the natural tendency for the gas to be driven towards the center of the female rotor is taken advantage of, making it much easier to extract practically all of the gas that has been compressed between the lobes.

The invention relates to a rotor pair for a compressor block of a screw machine, wherein the a rotor pair comprises a secondary rotor that rotates about a first axis and a main rotor that rotates about a second axis, wherein the number of teeth of the main rotor is 3 and the number of teeth of the secondary rotor is 4. The relative profile depth of the secondary rotor is at least 0.5, preferably at least 0.515, and at most 0.65, preferably at most 0.595. rk1 is an addendum circle radius drawn around the outer circumference of the secondary rotor and rf1 is a dedendum circle radius starting at the profile base of the secondary rotor, wherein the ratio of the axis distance of the first axis from the second axis and the addendum circle radius rk1 is at least 1.636, and at most 1.8, preferably at most 1.733.

A motor includes a shaft rotatable about an axis, an engaged component engaged by the shaft, a sleeve fixed to the shaft to rotate therewith, and a seal at least partly circumscribing the shaft. The shaft includes an engagement region presenting a substantially variable outer shaft surface that at least in part engages the engaged component. The sleeve includes a first section that at least partly circumscribes and engages the engagement region of the shaft. The first section of the sleeve presents an outer seal-engaging surface and an outer bearing-engaging surface. The seal and the bearing each at least partly circumscribe the engagement region of the shaft and the first section of the sleeve to engage the seal-engaging surface and the bearing-engaging surfaces, respectively, of the sleeve.

An electric pump includes a housing that includes a gear chamber, a rotor chamber, and a motor chamber. The electric pump includes a first seal member, a second seal member, and a third seal member. The first seal member seals a space between the gear chamber and the rotor chamber. The second seal member seals the space between the gear chamber and the rotor chamber. The third seal member seals a space between the gear chamber and the motor chamber. The third seal member seals the space between the gear chamber and the motor chamber to a lesser extent than the first seal member and the second seal member seal the space between the gear chamber and the rotor chamber.

A motor includes a shaft rotatable about an axis, an engaged component engaged by the shaft, a sleeve fixed to the shaft to rotate therewith, and a seal at least partly circumscribing the shaft. The shaft includes an engagement region presenting a substantially variable outer shaft surface that at least in part engages the engaged component. The sleeve includes a first section that at least partly circumscribes and engages the engagement region of the shaft. The first section of the sleeve presents an outer seal-engaging surface and an outer bearing-engaging surface. The seal and the bearing each at least partly circumscribe the engagement region of the shaft and the first section of the sleeve to engage the seal-engaging surface and the bearing-engaging surfaces, respectively, of the sleeve.

A pair of co-operating screw rotors including a male rotor and a female rotor. The male rotor and the female rotor have helically extending lobes and intermediate grooves configured to intermesh with one another. Each groove of the female rotor has a first flank including at least three concave sections. A first section includes or is disposed immediately adjacent the radially innermost point of the groove. A second section is shaped as a circular arc with a radius having its center located outside the pitch circle. A third section is shaped as a circular arc with a radius having its center located outside the pitch circle. The radius of the third section is greater than the radius of the second section, which is greater than the radial distance between a pitch circle of the female rotor and the radially innermost point of the groove.

A positive displacement device that converts energy, namely positive displacement compressors that rotate in a single rotational direction to displace working fluid contained in operating chambers. The device described herein is particularity advantageous for the ability to achieve high compression ratios in combination with high discharge pressure and high volumetric throughput in a single stage.