A lubricant-sealed vacuum pump configured to pump fluid from an inlet to an exhaust, method and filter are disclosed. The lubricant-sealed vacuum pump comprises: a rotor; a filter for filtering lubricant from fluid to be output by the pump; control circuitry for controlling a speed of rotation of the rotor, the control circuitry being configured to control rotation of the rotor, such that the rotor rotates at a reduced speed initially when a pressure at the inlet is high and rotates at a higher operational speed when the pressure at the inlet has reduced.

A pump unit includes a rough-vacuum pump and a Roots vacuum pump connected in series and upstream of the rough-vacuum pump in the direction of flow of the pumped gases. The Roots vacuum pump has three pumping stages in which the rotors are designed to be driven simultaneously in rotation by a motor of the Roots vacuum pump. A ratio of the flow rate generated by the first pumping stage of the rough-vacuum pump in the direction of flow of the pumped gases over the flow rate generated by the last pumping stage of the rough-vacuum pump is less than or equal to four.

A device evacuates a chamber and purifies the gas extracted from said chamber of any foreign substances. The device comprises a dry-condensing vacuum pump having an input connected to the chamber to be evacuated and is suitable for maintaining the input pressure at a constant level at the output despite variable conditions. An intermediate line which connects to the output of the dry-condensing vacuum pump and a liquid ring vacuum pump, the input of which is connected to the intermediate line, are additionally provided. A corresponding method makes it possible to purify the gas of any foreign substances reliably and effectively.

A pump unit includes a rough-vacuum pump and a Roots vacuum pump connected in series and upstream of the rough-vacuum pump in the direction of flow of the pumped gases. The Roots vacuum pump has three pumping stages in which the rotors are designed to be driven simultaneously in rotation by a motor of the Roots vacuum pump. A ratio of the flow rate generated by the first pumping stage of the rough-vacuum pump in the direction of flow of the pumped gases over the flow rate generated by the last pumping stage of the rough-vacuum pump is less than or equal to four.

A multi-stage dry Roots vacuum pump, including a pump body, multi-stage Roots working units and a plurality of drive components. The pump body is provided with a plurality of independent working chambers, and airflow channels communicating the various working chambers; the airflow channels are communicated with outside; the Roots working units of each stage include driving Roots rotors and driven Roots rotors; the driving Roots rotors and driven Roots rotors are positioned in the working chambers; and the various drive components are respectively used for driving the driving Roots rotors and driven Roots rotors positioned in the various working chambers to rotate towards opposite directions at the same rotating speed. The Roots working units of various stages may be randomly distributed at various positions of the pump body on premise of ensuring that the airflow channels can communicate the working chambers of each stage.

A method for treating a surface of a machine part, the method including the steps of: applying a pattern onto the surface of the machine part by means of a laser; and applying a coating onto the patterned surface

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.

Disclosed is a system for treating exhaust fluid from semiconductor manufacturing equipment in which cleaning gases decomposed by a plastic apparatus alternately flow towards a front rotor region (a main rotor unit) and a rear rotor region (a subsidiary rotor unit) of a booster pump and then flow towards a dry pump, and thus uniformly react with process byproducts present throughout the whole area in a vacuum pump including the booster pump and the dry pump so as to improve removal efficiency of the process byproducts. Further, the retention time of the cleaning gases decomposed by the plasma apparatus in the vacuum pump is increased by adjusting the pressure in the pump with the rotational speed of a motor, and thus the reaction time of the cleaning gases with the process byproducts is increased, so as to further improve removal efficiency of the process byproducts, such as SiO.sub.2 powder.

An automotive auxiliary assembly vacuum pump includes a housing composite structure with an electric motor section, a pump section, a pump inlet opening, and a pump outlet opening, a motor housing part, a bearing plate which closes the motor housing part proximally, and a pump rotor with a rotor body. The electric motor section includes a motor rotor which is surrounded by the motor housing part and which is closed by the bearing plate. The pump section includes a pump housing which defines a pump chamber and which includes a closure element, at least one pump chamber inlet opening, and at least one pump chamber outlet opening. The pump housing is formed at least by axially proximal and axially distal thrust washers and a radial thrust ring. Only the bearing plate and the axially proximal thrust washer are provided as a single-piece flange element.

A pumping unit is provided, including a primary vacuum pump of a multistage dry type, including at least four pumping stages fitted in series; and a two-stage Roots vacuum pump, including a first pumping stage and a second pumping stage fitted in series, the second pumping stage being fitted in series with and upstream of a first pumping stage of the primary vacuum pump in a direction of flow of gases to be pumped, in which a ratio of a volume displacement of the first pumping stage of the two-stage Roots vacuum pump to a volume displacement of the second pumping stage of the two-stage Roots vacuum pump is less than six, and in which a ratio of a volume displacement of the second pumping stage of the two-stage Roots vacuum pump to a volume displacement of the first pumping stage of the primary vacuum pump is less than six.