Oil feed nut and oil reservoir for a vacuum pump

Abstract

Oil feed nut for providing a lubricant to a bearing of a vacuum pump comprising a first end and an opposite second end and being configured to be connected to a shaft of the vacuum pump. Further, the oil feed nut comprising an oil feeding element extending between the first end and the second end, wherein the oil feeding element has an increasing diameter towards the second end to create an increasing rotational force acting on the lubricant in order to convey the lubricant towards the second end, and a bearing journal element having a cylindrical surface configured to be received in a back-up bearing of the vacuum pump. Therein, the back-up bearing is arranged in a cartridge of an oil reservoir.

Claims

1. An oil reservoir configured to be connected to a housing of a vacuum pump, comprising: a cartridge containing a lubricant to be provided to a bearing of the vacuum pump, a feeding tip to be in contact with an oil feed nut of the vacuum pump to apply the lubricant onto a surface of the oil feed nut, and a back-up bearing arranged in the cartridge configured to receive a bearing journal element of the vacuum pump.

2. The oil reservoir according to claim 1, characterized as being releasably connected to the vacuum pump.

3. A vacuum pump, comprising: a housing, a rotor shaft disposed in the housing, the oil reservoir according to claim 1 connected to the housing, wherein the oil feed nut is connected to the rotor shaft comprising an oil feeding element extending between a first end and a second end of the oil feed nut, wherein the oil feeding element has an increasing diameter towards the second end to create an increasing rotational force acting on the lubricant in order to convey the lubricant towards the second end, and the bearing journal element being connected to the oil feed nut or the rotor shaft having a cylindrical surface configured to be received in the back-up bearing of the oil reservoir.

4. The vacuum pump according to claim 3, characterized in that the rotor shaft comprises a first end towards an outlet of the vacuum pump and an opposite second end towards an inlet of the vacuum pump, wherein the oil feed nut is connected to the first end of the rotor shaft.

5. The vacuum pump according to claim 4, characterized in that the oil reservoir surrounds the first end of the rotor shaft.

6. The vacuum pump according to claim 3, characterized in that the cylindrical surface of the bearing journal element having a smaller diameter than an inner diameter of the back-up bearing such that in normal operation of the vacuum pump, the cylindrical surface is not in contact with the back-up bearing.

7. A kit comprising: an oil feed nut comprising: a first end and an opposite second end and being configured to be connected to a shaft of a vacuum pump, an oil feeding element extending between the first end and the second end, wherein the oil feeding element has an increasing diameter towards the second end to create an increasing rotational force acting on a lubricant in order to convey the lubricant towards the second end; and a bearing journal element having a cylindrical surface configured to be received in a back-up bearing of the vacuum pump, wherein the bearing journal element is arranged at the first end and the oil feeding element is arranged at the second end; and an oil reservoir configured to be retrofitted to the vacuum pump, the oil reservoir comprising: a cartridge containing the lubricant to be provided to a bearing of the vacuum pump, a feeding tip to be in contact with the oil feed nut of the vacuum pump to apply the lubricant onto a surface of the oil feed nut, and the back-up bearing arranged in the cartridge configured to receive the bearing journal element of the oil feed nut.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the present invention is described in more detail with reference to the accompanied drawings.

(2) It is shown:

(3) FIG. 1 a vacuum pump according to the present invention

(4) FIG. 2 a detailed view of the oil feed nut according to the present invention and

(5) FIG. 3 a second embodiment of the oil feed nut according to the present invention.

DETAILED DESCRIPTION

(6) The vacuum pump 10 comprises a housing 12 having an inlet 14 and an outlet 16. In the housing 12 a rotor shaft 18 is disposed having one or more pump elements 20 interacting with stator elements 22 of the housing 12. In the example of FIG. 1, the vacuum pump 10 is a turbomolecular vacuum pump wherein the pump elements 20 are built by vanes interacting with vanes of the stator elements 22. The rotor 18 is rotated by an electro motor 24 and due to rotation of the rotor shaft 18, a gaseous medium is conveyed from the inlet 14 to the outlet 16. Therein, the rotor 18 is rotatably supported by a first bearing 26 built as a magnetic bearing at the side of the inlet 14 of the vacuum pump 10. A second bearing supporting the rotor shaft 18 is built as ball bearing 28 at the outlet side of the rotor shaft at a first end 30 of the rotor shaft 18 opposite to a second end 32 of the rotor shaft 18.

(7) To the first end 30 of the rotor shaft 18 an oil feed nut 34 is connected shown in more detail in FIG. 2 having a first end 38 and an opposite second end 39. Therein, the oil feed nut 34 comprising an oil feeding element 36 having an outer surface with an increasing towards a second end 39 of the oil feeding element 34. Thus, the oil feeding element 36 having a cone shaped outer surface. Further, the oil feed nut 34 is at least partly surrounded by an oil reservoir 40 which is releasably connected to the housing 12 of the vacuum pump. In particular, the oil reservoir 40 is inserted into a recess of the housing 12 in order to provide easy access to the oil reservoir 40 during maintenance of the vacuum pump. The oil reservoir 40 comprises a cartridge 42 containing and storing a lubricant to be provided to the ball bearings 28. Therein, the cartridge 42 can be filled with a fibrous or porous material to store the lubricant. To this material a feeding tip 44 is connected which is in contact with the conical surface of the oil feeding element 36 of the oil feed nut 34. Preferably, also the feeding tip is made from a fibrous or porous material drawing a lubricant from the cartridge 42 via capillary force and applying the lubricant onto the surface of the oil feeding element 36 of the oil feed nut. The oil feed nut 34 is rotated in conjunction with the rotor shaft 18. Due to rotation of the oil feeding nut by the shaft 18 of the vacuum pump the lubricant is conveyed by the centrifugal force towards the ball bearing 28, wherein the second end of the oil feeding nut 34 is within or in the range of the ball bearing 28. Thus, the lubricant is conveyed from the feeding tip 44 via the oil feeding element 36 to the second end of the oil feeding element 34 and dripping from there to the ball bearing 28 of the vacuum pump 10.

(8) Further, as shown in FIG. 2, the oil feeding nut 34 further comprises a bearing journal element 46 having a cylindrical outer surface. The bearing journal element 46 is interacting with a back-up bearing 48 disposed in the cartridge 42 of the oil reservoir 40. Therein, the back-up bearing 48 can be built as ball bearing, friction bearing or the like. Therein, in normal operation of the vacuum pump the bearing journal element 46 of the oil feed nut 34 does not come into contact with the back-up bearing 48 due to a smaller diameter of the bearing journal 46 than the inner diameter of the back-up bearing 48. In case of malfunction of the vacuum pump the bearing journal element 46 comes into contact with the back-up bearing 48 and provides minimum support of the rotor shaft 18.

(9) Since the back-up bearing 48 is implemented in the oil reservoir 40 which is a replaceable part and can be replaced during maintenance, it is also possible to retrofit a back-up bearing to existing vacuum pumps. Therefore, in a first step the old oil reservoir is removed. Second, the old oil feed nut is also removed. Third, a new oil feed nut as shown for example in FIG. 2 having a bearing journal element 46 is installed on the first end 30 of the rotor shaft 18. Fourth, an oil reservoir according to the present invention is installed including the back-up bearing 48 interacting with the bearing journal element 46 of the oil feed nut 34.

(10) FIG. 3 shows another embodiment, wherein same or similar elements are indicated by identical reference signs. Therein, the oil feed nut 34 comprises a though hole 50 extending through the oil feed nut 34. The through hole 50 is configured to receive a part of the rotor shaft 18 such that the first end 30 of the rotor shaft 18 is extending through the oil feed nut 34 and providing the bearing journal element 52. Thus, the back-up bearing interacting with bearing journal element provided by the rotor shaft 18 itself for ease of concentricity.

(11) Thus, by the present invention a combined system is provided, providing a lubricant to a ball bearing of the vacuum pump and further providing a back-up bearing avoiding severe damage and even destruction of the vacuum pump. Further, by the kit including the oil feed nut according to the present invention and the oil reservoir according to the present invention it is easily possible to retrofit existing vacuum pumps in order to provide increased safety by the back-up bearing.

(12) Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

(13) Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.