A screw compressor includes an outlet housing. The outlet housing includes a passage that is configured to communicate compressed fluid from a screw rotor to a discharge. A removable cover plate is configured to cover a portion of the passage. A method of varying a volume index for a screw compressor is also disclosed.

The invention relates to a screw pump having two screws, in which screw pump each screw has a first thread and a second thread. The threads extend in each case from a suction side to a delivery side. The threads are in engagement with one another, with the result that the threads are divided into a plurality of working chambers, the volume of which decreases from the suction side to the delivery side. According to the invention, the threads have two thread turns. Moreover, the invention relates to a screw for a pump of this type. On account of the uniform distribution of mass of the two-turn threads, the pump can be operated at a high rotational speed, with the result that the throughput of the pump is increased.

A pump includes a first housing part defining a first portion of a bore extending within the first housing part and shaped to receive a rotor; and a second housing part defining a second portion of the bore extending within the second housing part and shaped to receive the rotor. The first housing part has a first face abutable against an opposing second face of the second housing part to position the first portion of the bore with the second portion of the bore to receive the rotor. The first portion of the bore has a first circular cross-section portion centered along the first face and the second portion of the bore having a second circular cross-section portion centered, within the second housing part, at a distance from the second face.

A manufacturing method of an end plate of a pump that can remove a sag includes: punching a workpiece from a plate material, the workpiece being the end plate including a mounting seat including a fastener; forming a pressed trace surface by pressing an outer edge of an outer surface, when a surface, of both front and back surfaces of the punched workpiece, further from a sag formed on a cut end surface is the outer surface, and a surface, of both front and back surfaces of the punched workpiece, nearer to the sag is an inner surface. A section of the pressed trace surface disposed along an outer edge of the mounting seat is a fastening section. A section of the pressed trace surface other than the fastening section is a non-fastening section. A radial width of the fastening section is shorter than that of the non-fastening section.

A device for painting a compressor or vacuum pump housing including a first semi-cylindrical structure adjoined to a second semi-cylindrical structure, a dispersing head including a rotating part having a bell shaped structure and a stationary part; a paint reservoir connected to the stationary part through a conduit; a supporting structure including fixing means. The device further includes a controller for controlling a rotational speed of the rotating part. The controller is provided with means for controlling a rotational direction of the rotating part in a clockwise direction for painting the first semi-cylindrical structure of the compressor or vacuum pump housing and for changing the rotational direction to a counterclockwise direction for painting the second semi-cylindrical structure of the compressor or vacuum pump housing.

A scroll compressor is provided which comprises: a housing; a driving motor; an orbiting scroll rotated by the driving motor; a fixed scroll; a suction port provided in the housing and suctioning a refrigerant; an oil separator in the housing at one side of the fixed scroll; and a discharge port for discharging, to the outside of the housing, the refrigerant from which oil is separated in the oil separator. The scroll compressor includes an intermediate housing; a back pressure chamber in the intermediate housing at one side of the orbiting scroll, first and second back pressure seal members in the intermediate housing; a plurality of anti-rotation rings in the intermediate housing; and a plurality of anti-rotation pins at the orbiting scroll to be inserted into each of the plurality of anti-rotation rings.

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 housing unit of a Roots pump includes a rotor housing, which includes a peripheral wall, and a cover member, which closes an opening of the rotor housing. At least one of a mating surface of the peripheral wall or a mating surface of the cover member includes an annular first groove accommodating a seal member. The rotor housing includes a bulging portion including a second groove. The seal member incudes first projections, which project from an annular seal body, and a second projection, which projects further radially inward from the seal body than the first projections. Each first projection includes a distal end that contacts a side surface on a radially inner side or on a radially outer side of the first groove. The second projection is arranged in the second groove to determine the position of the seal body in the first groove.

A method for evacuating a chamber employs a pump arrangement composed of a booster pump and of a downstream forepump is connected to the chamber. The booster pump is accelerated, gas from the chamber is introduced into the booster pump, such that from the booster pump there is temporarily extracted an excess power which exceeds the power provided by the drive of the booster pump. The gas is discharged through a bypass valve while the outlet pressure of the booster pump lies above a predefined threshold value, and the gas is directed to the forepump when the outlet pressure of the booster pump has fallen below the threshold value. The gas supplied by the booster pump is compressed by means of the forepump.

A housing unit of a Roots pump includes a rotor housing, which includes a peripheral wall, and a cover member, which closes an opening of the rotor housing. At least one of a mating surface of the peripheral wall or a mating surface of the cover member includes an annular first groove accommodating a seal member. The rotor housing includes a bulging portion including a second groove. The seal member incudes first projections, which project from an annular seal body, and a second projection, which projects further radially inward from the seal body than the first projections. Each first projection includes a distal end that contacts a side surface on a radially inner side or on a radially outer side of the first groove. The second projection is arranged in the second groove to determine the position of the seal body in the first groove.