Leybold Vakuum Gmbh

Oerlikon Leybold Vacuum Gmbh

Leybold Vacuum Gmbh

Hartmut Kriehn

Klaus Rofall

Manfred Behling

Thomas Dreifert

Lothar Brenner

Ralf Steffens

Wolfgang Giebmanns

Michael Froitzheim

Hans-Rochus Gross

A screw-type vacuum pump () is tempered such that characteristics of the pump are not substantially altered when the pump is subjected to thermal stress. In order to achieve said aim, cooling is adjusted according to an operating state of the screw-type vacuum pump (), preferably to maintain a substantially constant pump gap ().

Tempering method for a screw-type vacuum pump

A vacuum pump () comprises at least one rotor shaft () having a rotor section () with a rotor (), a bearing section () with a bearing (), and a shaft sealing system () that is axially situated between the rotor section () and the bearing section (). The shaft sealing system () axially comprises, on the side of the rotor, a gas seal () and, on the side of the bearing, an oil seal (). The shaft sealing system () additionally comprises, between the gas seal () and the oil seal (), a separating chamber, which surrounds the rotor shaft () and is ventilated by at least one separating chamber ventilation duct (). This enables the pressure difference that decreases via the gas seal and the pressure difference that decreases via the oil seal to be adjusted. An appropriate adjustment can prevent oil on the bearing side from passing through the oil seal toward the separating chamber.

Vacuum pump

A screw-type vacuum pump () includes a pump housing () with rotors (). A liquid cooling system cools the rotors and a drive motor (). In order to improve the cooling of said pump, an external air-flow impelled cooling system is also provided for the pump housing ().

Cooled screw-type vacuum pump

A vacuum pump () comprising a pump chamber casing () accommodating two co-operating rotors () which are respectively arranged on a shaft (). A bearing/gear chamber () is disposed adjacent to the pump chamber casing () in which the rotor shafts () are cantilevered and provided with a synchronisation gear (). A drive motor () whose drive shaft () extending parallel to the rotor shafts () and is provided with a drive gear (). A gear stage () is disposed between the drive shaft () and one of the rotor shafts (). In order to provide a machine of this type which can be embodied in a compact form, the drive gear () of the drive shaft () engages directly with a driven gear () on one of the rotor shafts (), forming the gear stage ().

Two shaft vacuum pump with cantilevered rotors

A vacuum pump has two shafts () and two rotors () which co-operate with each other and which are fixed to the shafts. The rotors are cantilevered on the shafts. The rotors are fixed to the shafts in a manner which is devoid of backlash, even during temperature changes. In order to achieve this, the shafts () are made of a material having a modulus of elasticity which is as high as possible, e.g., steel. The rotors () are made of a material having a density which is as low as possible, e.g., aluminum or a titanium alloy. Structures (; etc.) are provided to ensure that the rotors () are fixed to the shafts () in a manner which is devoid of backlash at all operating temperatures.

Two-shaft vacuum pump

A screw vacuum pump ( ) has shafts ( ) and rotors ( ) secured to the shafts. Each rotor has a central hollow chamber ( ) which receives the shaft or contains in built-in components rotating along with the rotor to define a relatively thin annular slot segment ( ) for cross-flow circulation of coolant. The annular slot segment is disposed between the built-in components and an inner wall of the rotor's hollow chamber and between a suction side and a delivery side of the rotor. Separate feed and discharge lines ( ) circulate the coolant through the annular slot segment in such a way that the coolant remains cavitation-free and bubble-free.

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Kö'ln, Germany

Hartmut Kriehn