A dry pump for gases comprises a first rotor (1) comprising a first lobe portion (1A) and a first screw (1B), as well as a second rotor (2) comprising a second lobe portion (2A) and a second screw (2B). A casing delimits an internal volume in which are located together the first and second screws (1B, 2B) and the first and second lobe portions (1A, 2A). Each of the first and second screws (1B, 2B) comprises a threading invariable along its length. The first and second rotors (1, 2) turn in opposite directions and are located in successive configurations. In a first configuration of the rotors, the first and second lobe portions (1A, 2A), a portion of the first screw (1B), a portion of the second screw (2B) and the casing together delimit a chamber (30) which is closed. In a second configuration of the rotors, the chamber (30) has a smaller capacity than in the first configuration. In a third configuration of the rotors, the chamber (30) is displaced entirely at the first and second screws (1B, 2B) and isolated from the lobe portions.

A screw compressor for compressing a working medium sucked through a suction opening and discharging the compressed working medium through a delivery opening, wherein the screw compressor includes: a male rotor and a female rotor that rotate while meshing with each other; a casing that houses the male rotor and the female rotor and is provided with a bore which forms a working chamber designed, together with the male rotor and the female rotor, to compress the working medium; a drive unit that rotationally drives at least one of the male rotor and the female rotor; a working chamber closing unit that forms a suction port for sucking the working medium into the working chamber and closes the working chamber when the working chamber reaches a specified capacity; and a suction space that connects the suction opening and the suction port to allow communication therebetween, wherein an open space that connects the suction opening and the suction port to allow communication therebetween is provided between a shaft of the male rotor and a shaft of the female rotor on an opposite side of the male rotor and the female rotor relative to the suction port.

A screw compressor includes a first rotor and a second rotor, and each rotor is provided with a synchronisation gear. The screw compressor is further provided with an electric motor and one or two driving gears for driving the first rotor or second rotor. At least one of the synchronisation gears or driving gears is provided with spokes between a rim supporting a gear mesh and a corresponding gear hub.

A screw compressor includes a screw rotor, a gate rotor, and a speed adjuster. The screw rotor has an outer peripheral surface with a plurality of screw grooves. The screw rotor is configured to be rotated. The gate rotor has a plurality of teeth. A ratio T/S of a number T of the teeth to a total number S of the screw grooves is greater than or equal to 2.5. The gate rotor meshes with the screw rotor. The speed adjuster is configured to adjust a rotational speed of the screw rotor. Rotation of the screw rotor at an angle greater than 180 allows the screw compressor to perform a stroke from start of compression to completion of discharge.

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 casing of a screw compressor has a delivery inner wall face facing delivery end faces of a male rotor and a female rotor. The delivery inner wall face of the casing has a shield area that shields at least a part of a track of an axial fluid communication path, which is a clearance that periodically occurs at the delivery end faces according to variation of intermeshing of the male and female rotors upon rotation thereof and is bounded by trailing flanks of the male and female rotors. The shield area of the casing is provided with a groove group made up of a plurality of grooves having longitudinal directions. The grooves of the groove group are juxtaposed in the circumferential direction of at least one rotor of the male and female rotors and are arranged such that their sides extending in the longitudinal directions are disposed adjacent to each other. Each groove of the groove group is configured such that its longitudinal direction oriented from the inner circumferential side of the one rotor toward the outer circumferential side is inclined with respect to the radial direction of the one rotor in the same direction as the rotational direction of the one rotor.

The utility model relates to internal cycloidal gear mechanisms and can be used in various branches of mechanical engineering as working members of hydraulic machines (pumps and engines), compressors, internal combustion engines, as well as in planetary gearboxes, in particular in technical systems for drilling and repairing oil and gas wells. The problems to be solved by the utility model include the improvement of the quality of the process of designing working members having a cycloidal tooth profile, as well as the substantiation of the conditions for modifying cycloidal face profiles (by choosing the required combination of dimensionless gearing coefficients) in order to achieve the maximum or minimum open area of the gerotor mechanism having a different kinematic ratio.

A rotor assembly, a compressor and an air conditioner are provided. The rotor assembly includes a first rotation shaft and a first rotor rotatably arranged on the first rotation shaft. The first rotor includes a plurality of first screw blades, and a first tooth slot is formed between two adjacent first screw blades; a suction end of the first rotor has at least one oil slinger slot, to allow a lubricant to enter the first tooth slot through the at least one oil slinger slot. It is ensured that the lubricant can fully lubricate and seal the first tooth slot, so that the compressor can run more smoothly, reduce wear of screw blades and improve the service life of the compressor.

A screw rotor lead correction calculation device includes an initial data input section configured to input an error as a distance with respect to a reference lead at each axial position of a rotor groove portion of a screw rotor, and a processing machine input correction amount/position output section configured to compute and output, based on the error as the distance input to the initial data input section, a lead correction amount with respect to the reference lead and a lead correction starting position as an axial position for starting lead correction. With this configuration, correction data for obtaining a screw rotor with a high-accuracy lead can be obtained from a lead error with respect to a reference lead in a screw rotor obtained by ground finish of the material of the screw rotor.

A multistage Roots pump comprise a plurality of pump chambers in a pump housing. They constitute respective pump stages, wherein each pump stage comprises two two-toothed rotary pistons. The pump stages are separated from each other by partition walls. In the partition walls essentially radially extending connecting ducts are arranged. The connecting ducts are connected with an inflow chamber whose inflow opening has a larger cross-section than the connecting ducts.