A vacuum pump screw rotor, comprising at least two helical displacer elements on a rotor shaft. The at least two displacer elements have different pitches, but the pitches of each displacer element are constant. Furthermore, the displacer elements each have a helical recess, each having a contour that remains the same over its entire length. Hereby, a suction-side displacer element has a recess having an asymmetric contour, and a pressure-side displacer element has a recess having a symmetrical contour.

A screw compressor system for a utility vehicle has at least one screw compressor, at least one screw compressor drive with an output shaft, at least one driven screw with a screw drive shaft section. The output shaft and the screw drive shaft section are essentially coaxial.

In a scroll machining method, a scroll has a disc-like end plate and a scroll wall extending from a first side surface of the disc-like end plate, and the scroll is driven to rotate around a center axis C of the scroll, and a first cutter machines a side wall surface of the scroll wall while the scroll is rotating. The first cutter is a non-rotary cutter. When the scroll is machined, the scroll rotates around its center axis, and the first cutter does not rotate around its axis, thereby improving the scroll's machining precision and machining efficiency.

Provided is a scroll fluid machine which is capable of inhibiting contact between tooth tip corners and tooth bottom corners. The present invention is provided with: a wall inclined portion (3b1) of which a facing surface has a distance to an end plate which continuously decreases from the outer circumferential side to the inner circumferential side; and an end plate inclined portion (5a1). Chamfered portions (8a) are provided to tooth tip corners (8) of a tooth tip of a wall (3b) which face tooth bottom corners (9) of bases of mating walls (5b). The chamfered portions (8a) have a shape which avoids contact with step parts (9a) which are formed at the tooth bottom, and which are adjacent to the tooth bottom corners (9).

A method of casting a rotor using a cavity and core mold allows a longitudinal slot oriented transversely to the axis of rotation to be finish ground to high precision and tight tolerances by casting the slot to have a wider section which extends from the axis to a radius greater than the radii of the hubs of the rotor, and a narrower section which extends from the wider section to the outer surface of the rotor. The geometrical relation of the slot sections to the hubs as cast permits the grinding step to be performed without forming a leak path in either of the hubs.

Described is a method for grinding workpieces, which comprise at least one cylindrical and profiled portion each, on one and the same grinding machine. The workpiece is ground initially in a first grinding operation in a first clamping in the grinding machine, said first grinding operation being followed by a second grinding operation once the first clamping has been released and then, before the start of the second grinding operation, a second clamping has been generated.

A scroll compressor for a motor vehicle air-conditioning system includes a compressor housing, two interleaving spirals within the compressor housing, of which one spiral is stationary and the other spiral is movable eccentrically on a circular orbit, whereby the volume of compression chambers formed between the spirals changes cyclically and refrigerant is suctioned in and compressed; at least one refrigerant outlet port for ejecting the compressed refrigerant in a wall, frontal to the spirals, of the compressor housing in the center of the stationary spiral, wherein in the spiral end region on the inner end of at least one of the two spirals the concave side of the spiral wall is provided with a cut that has the form of a cone segment with concave curvature, decreasing from the upper end in the direction toward the lower end of the spiral wall.

A screw pump comprising a housing defining a chamber and two screw rotors. Wherein each screw rotor comprises a rotor shaft and at least two displacement elements connected with the rotor shaft. Each displacement element having at least one helical protrusion. One of the displacement elements is a suction-side displacement element arranged in a suction-side section of the chamber. Another one of the displacement elements is a pressure-side displacement element arranged in a pressure-side section of the chamber. The suction-side displacement element is designed tapering in the conveying direction. The clearance between the pressure-side displacement element and the pressure-side section of the chamber at least partly decreases in the conveying direction. Furthermore, a screw rotor, a method of manufacturing a screw rotor and a use of a screw pump or a screw rotor.

A fluid displacement apparatus includes a stator section with a rotor therein. The stator section includes a cylindrical casing, a helically-convoluted chamber section within the cylindrical casing, and a rigid sleeve within the cylindrical casing and separate from the helically-convoluted chamber section. The rigid sleeve includes a circular internal bore. The rotor is rotatably disposed within the cylindrical casing. The rotor includes a helically-lobed section disposed within the helically-convoluted chamber section, and a circular cylinder section disposed within the rigid sleeve. The circular cylinder section provides a fluid passageway between the rigid sleeve and the circular cylinder section. Side loads from the rotor are distributed along a contact line at any point of rotation of the circular cylinder section within the rigid sleeve.

An orbiting scroll of a scroll compressor includes a platter wall having a first face including a spiral structure projecting therefrom, a second face having a coupling structure configured to couple the orbiting scroll to a drive mechanism of the scroll compressor, and a circumferential surface connecting the first face to the second face in an axial direction of the platter wall. The orbiting scroll includes a mass reduction feature provided as an inwardly indented channel formed in the circumferential surface. The channel is further configured to form a retaining feature for retaining a rim of a mask during a process of coating the spiral structure of the first face with a surface coating.