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.

The invention relates to a rotor pair for a compressor block of a screw machine, wherein the 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 screw vacuum pump comprises a housing forming a pumping chamber, wherein the housing is made of aluminum or an aluminum alloy. Further provided are two screw rotors arranged in the pumping chamber, each screw rotor comprising at least one displacer element having a helical recess for forming a plurality of windings, wherein the at least one displacer element is made of aluminum or an aluminum alloy. Between the region in which prevail 5% to 30% of the outlet pressure and a pressure-side end of the rotor (pump outlet), at least six, particularly at least eight, and with particular preference at least ten windings are provided.

A rotor comprises a central body configured to rotate. A lobe extends perpendicularly from the central body along an lobe axis. A curved leading periphery and a curved trailing periphery are on opposite sides of the lobe axis. A V-shaped rib spans between the curved leading periphery and the curved trailing periphery. A first hollow space is bounded by the V-shaped rib, the curved leading periphery, and the curved trailing periphery. The first hollow space is distal with respect to the central body along the lobe axis. A second hollow space is bounded by the V-shaped rib, the central body, the curved leading periphery, and the curved trailing periphery. The second hollow space is proximal with respect to the central body along the lobe axis. The rotor can comprise a plurality of stacked, stamped sheets to form a helically twisted supercharger rotor.

Provided is an internal gear pump. The shape of any one of a plurality of external teeth and a plurality of internal teeth of the pump is formed on the basis of formulae (1)-(5).
r=rodr.Math.cos ,Formula (1):
Px=(rodr)+1/4dr{1cos(2)},Formula (2):
Py=1/4dr{2+sin(2)},Formula (3):
Qx=Pxr.Math.cos ,Formula (4):
Qy=Py+r.Math.sin Formula (5):.

A dry-compressing vacuum pump, in particular a screw pump, has two rotor elements (14) which are arranged in a pump chamber (12) and which are each carried by a rotor shaft (22). Two shaft ends of the rotor shafts (22) project through a side wall (28) of the pump housing (10). On the two shaft ends (28) there is arranged in each case one toothed belt pulley (38). Furthermore, a drive device and an electric motor for driving the rotor shaft (22) are provided. According to the invention, the rotor shafts (22) are driven by means of a toothed belt (40). To be able to use a toothed belt for drive purposes, a rotational flank clearance between the two rotor elements (14) of greater than 0.75, in particular greater than 1, is provided.

The present disclosure provides a method for modifying performance of a rotor profile by adjusting meshing line segments, including the following steps: step 1, dividing a meshing line of a bilateral profile into eight functional segments; step 2, constructing each functional segment by using a cubic NURBS curve; and step 3, locally adjusting the functional segments of the meshing line by adjusting control points or weight factors of the NURBS curve, and observing corresponding changes of the rotor profile so as to adjust corresponding geometrical parameters. The design means is flexible and convenient, the change of the profile is controlled by adjusting the free curve, and the meshing line is locally adjusted in combination with the corresponding relationship between the meshing line and the rotor profile to observe the corresponding change trends, particularly the changes in leak triangle, contact line length, inter-tooth area and area utilization coefficient, of the male and female rotor profile, so that the design efficiency of the rotor profile of a twin-rotor screw compressor is improved, and the defect in the prior art that the rotor profile cannot be locally modified is avoided.

Gear pump with intermeshing gear wheels enclosed by a housing with bearing journals arranged on shaft axes, each projecting laterally from the gear wheels, which are mounted in the housing by means of slide bearings, having a slide bearing length, the slide bearings being lubricated with pumped medium. The invention is characterized in that a filling pocket with radial expansion is incorporated in each of the slide bearings in the region of a pump pressure side, the filling pocket being spaced from a gear-side end face of the respective slide bearing by a distance, so that a bar with a bar width with axial expansion corresponding to a slide bearing surface is formed, and in that a lubrication groove with a tampering cross-section is provided in each of the slide bearings, the lubricating groove starting from an end on the gearwheel side towards a slide bearing end and starting at the filling pocket on the gearwheel side and communicating therewith.

This screw compressor is provided with a screw rotor, a casing accommodating the screw rotor, and a liquid feed mechanism for feeding a liquid into an operating chamber enclosed by the casing, wherein the pitch of the screw rotor changes in the axial direction from a suction end surface toward a discharge end surface.

The objective of the present invention is to reduce loss factors that occur inside an oil-cooled screw compressor and to improve energy efficiency. In oil-cooled screw compressors, compression is carried out by reducing the volume of an operation chamber in which a gas to be compressed and an oil are mixed and contained, and when a predetermined rise in pressure is complete, a discharge port opens and the gas to be compressed and the oil are discharged. In the operation chamber, the reduction in volume continues and reaches zero, such that the operation chamber disappears, and the opening area of the discharge port also gradually decreases. Immediately before the operation chamber disappears, the ratio of the oil within the operation chamber is high and the opening area of the discharge port is small. Therefore, the discharge resistance increases and the internal pressure dramatically rises, and this has led to increases in the torque rotating the rotor. Thus, in the present invention, a tooth crest arc of a fixed width is provided to the tooth crest of a male tooth profile, and simultaneously a tooth bottom arc is provided to the tooth bottom of a female tooth profile. Due to the actions thereof, the operation chamber immediately before disappearing exists only in a bottom half region from a line that connects the centers of the male and female tooth profiles, and the opening area relative to the volume of the operation chamber can be increased. As a result, the discharge of oil becomes smooth and energy loss is reduced.