VACUUM-PUMP ROTOR

Abstract

A vacuum pump rotor comprises at least one displacement element arranged on a rotor shaft. The rotor shaft comprises at least one shaft end for a bearing element to be arranged thereon. The rotor element, the at least one displacement element and the at least one shaft end are made from aluminum or an aluminum alloy.

Claims

1. A vacuum pump rotor, comprising at least one displacement element arranged on a rotor shaft, wherein said rotor shaft comprises at least one shaft end for a bearing element to be arranged thereon, wherein said rotor shaft, said at least one displacement element and said at least one shaft end are made from aluminum or an aluminum alloy.

2. The vacuum pump rotor according to claim 1, wherein on the rotor shaft at least two displacement elements are arranged.

3. The vacuum pump rotor according to claim 1, wherein the rotor shaft and at least one of the displacement elements are integrally formed.

4. The vacuum pump rotor according to claim 1, wherein the rotor shaft and all displacement element are integrally formed.

5. The vacuum pump rotor according to claim 1, wherein the aluminum used or the aluminum alloy used has a thermal expansion coefficient which is smaller than or equal to 2110.sup.6/K.

6. The vacuum pump rotor according to claim 1, wherein the aluminum alloy used comprises a high silicon content of about least 15%.

7. The vacuum pump rotor according to claim 1, wherein the surface of the at least one displacement element and/or the rotor shaft is provided with a wear-reducing coating.

8. The vacuum pump rotor according to claim 1, wherein the at least one shaft end comprises a bushing from a harder material, in particular steel or a ceramic material.

9. The vacuum pump rotor according to claim 8, wherein the bushing is pressed onto the at least one shaft end or is molded into said at least one shaft end.

10. The vacuum pump rotor according to claim 1, wherein the surface of at least one of the displacement elements is provided with an emergency operation coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Hereunder the disclosure is explained in detail on the basis of a preferred embodiment with reference to the accompanying drawing in which:

[0015] FIG. 1 shows a schematic side view of a screw rotor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Hereunder the disclosure is described on the basis of an exemplary screw rotor, wherein the disclosure is in particular also applicable to rotors for claw pumps, Roots pumps and multistage claw and Roots pumps.

[0017] In the illustrated exemplary embodiment, a vacuum pump rotor of a screw pump comprises a rotor shaft 10 on which two displacement elements 12, 14 are arranged. In particular, the rotor shaft 10 and the displacement elements 12, 14 are integrally formed. In the illustrated exemplary embodiment, the two displacement elements 12, 14 have different pitches, wherein the displacement element 14 having a larger pitch is connected to the inlet of the vacuum pump on the left-hand side in the Figure and the displacement element 12 having the smaller pitch is connected to the outlet of the vacuum pump on the right-hand side in the Figure.

[0018] In the illustrated exemplary embodiment, the rotor shaft 10 comprises two shaft ends 16 since this is a vacuum pump rotor mounted on both sides in the illustrated exemplary embodiment. The two shaft ends 16 serve for accommodating bearing elements. The two shaft ends 16 may additionally be provided with a bushing not illustrated which is in particular made from a harder material. The bushing may be pressed onto or molded into the shaft ends.

[0019] The illustrated vacuum pump rotor is preferably formed as a single piece such that the shaft 10 including the shaft ends 16 and the two displacement elements 12, 14 is made from one material, in particular aluminum or an aluminum alloy.

[0020] Further, the illustrated vacuum pump rotor comprises a shaft projection 18. The latter serves for accommodating a gearwheel, for example, via which the rotor shaft 10 is driven or possibly synchronized with the second screw pump rotor. Preferably, the projection 18 is also integrally formed with the shaft 10 and made from the same material.

[0021] Surfaces 20, 22 of the displacement element 14 may be provided with a wear-reducing coating and/or a coating imparting emergency operation properties. This is also possible on a surface 24 of the rotor shaft 10. Of course, corresponding coatings may also be provided on the displacement element 12.

[0022] If the shaft ends 16 are not provided with a bushing, it is preferred to provide the surface 26 of the shaft ends 16 with a wear-reducing coating.