Oil supply nut and oil reservoir for vacuum pump

Abstract

An oil supply nut for supplying lubricant to a bearing of a vacuum pump has a first end and an opposite second end and is configured to couple to a shaft of the vacuum pump. The oil supply nut further includes an oil supply element extending between the first end and the second end, the oil supply element having an increasing diameter toward the second end and configured to generate a large rotational force acting on the lubricant to transport it toward the second end, and a bearing journal element having a cylindrical surface configured to be received in a backup bearing of the vacuum pump, where the backup bearing is disposed within a cartridge of an oil reservoir.

Description

[Technical field]

[0001] The present invention relates to an oil supply nut for supplying lubricant to bearings of a vacuum pump, an oil reservoir for containing and supplying lubricant, a kit including such an oil supply nut and oil reservoir for retrofitting to an existing vacuum pump, and a vacuum pump having such an oil supply nut and oil reservoir. [Background technology]

[0002] Existing vacuum pumps, particularly turbomolecular pumps, comprise a housing having an inlet and an outlet. A rotor shaft having at least one pump element interacting with at least one stator element is rotatably arranged within the housing. The rotor shaft is rotated by an electric motor and the interaction of the at least one pump element with the at least one stator element transports a gaseous medium from the inlet to the outlet of the vacuum pump. The rotor shaft is rotatably supported by one or more bearings, which may be roller bearings, such as ball bearings.

[0003] During operation, the roller bearings need to be lubricated to reduce wear and fatigue of the roller bearings. Typically, the lubricant is contained in an oil reservoir, from which it is supplied to the roller bearings by an oil supply nut. In that case, the oil reservoir needs to be replaced from time to time during maintenance of the vacuum pump to ensure proper functioning and sufficient supply of lubricant to the roller bearings.

[0004] Due to the high speed rotation of the rotor shaft in the event of a vacuum pump failure, the rotor shaft, specifically the pump element, may collide with the stator, causing serious damage to and even destruction of the vacuum pump, and there is also a risk of injury to the operator. It is therefore desirable for the vacuum pump to have a backup bearing to support the rotor shaft in the event of a failure and to avoid destruction of the rotor housing or the stator element. However, it is difficult to arrange both the backup bearing and the oil reservoir together with the oil supply nut. Due to the need for lubrication of the roller bearings, the backup bearing is often omitted. In particular, in existing vacuum pumps without a backup bearing, there is little possibility to retrofit a backup bearing to increase the safety of the operation of this vacuum pump. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide the possibility of having an oil supply nut and a backup bearing together, and further to provide the possibility of retrofitting such a backup bearing to an existing vacuum pump without major intrusion into the vacuum pump. [Means for solving the problem]

[0006] The above given problem is solved according to the invention by an oil supply nut according to claim 1, an oil reservoir according to claim 6, a kit comprising such an oil supply nut and such an oil reservoir according to claim 8 and a vacuum pump according to claim 9.

[0007] In a first aspect of the present invention, an oil supply nut for supplying lubricant to a bearing of a vacuum pump is provided. The oil supply nut comprises a first end and an opposite second end, and is configured to be coupled to a rotor shaft of the vacuum pump. In particular, the oil supply nut is releasably coupled to the rotor shaft of the vacuum pump. Furthermore, the oil supply nut comprises an oil supply element extending axially between the first end and the second end of the oil supply nut, the oil supply element having a diameter that increases toward the second end so as to be conical. The increasing diameter increases the rotational force acting on the lubricant at the surface of the oil supply element, whereby the lubricant is conveyed toward the second end and from the second end to a bearing of the vacuum pump disposed near the second end of the oil supply nut. According to the present invention, the oil supply nut comprises a bearing journal element having a cylindrical surface and configured to be received in a backup bearing of the vacuum pump. Thus, in accordance with the present invention, the oil supply nut provides two combined functionalities, namely, the function of supplying lubricant from an oil reservoir to the bearings by way of an oil supply element, and the function of providing a bearing journal element which interacts with the back-up bearing of the vacuum pump to support the rotor shaft of the vacuum pump in the event of a vacuum pump failure, and thus, because these functionalities are combined into a single part, it is easy to manufacture and can be retrofitted to existing vacuum pumps.

[0008] Preferably, the bearing journal element and the oil supply element are integrally constructed as one piece.More preferably, the oil supply nut is constructed as one piece.

[0009] Preferably, the bearing journal element is located at a first end of the oil supply nut and the oil supply element is located at a second end, more particularly, the bearing journal element is directly adjacent to the oil supply element.

[0010] Preferably, the oil supply nut comprises a coupling element which is coupled to the rotor shaft of the vacuum pump. The coupling element thus facilitates coupling of the oil supply nut to the rotor shaft of the vacuum pump. In particular, the coupling element releasably couples the oil supply nut to the rotor shaft. In each case, the coupling element can be provided by a threaded connection, a shrink fit, a clamp, etc.

[0011] Preferably, the coupling element is located at the second end. Alternatively, the oil supply nut includes a through hole extending through the oil supply nut from the first end to the second end and configured to receive a portion of a rotor shaft of the vacuum pump, and the coupling element is located at the first end, such that the oil supply nut is coupleable to the rotor shaft with the coupling element at the first end. The through hole allows the oil supply nut to surround the rotor shaft and improves concentricity of the rotor shaft and the oil supply nut.

[0012] In a second aspect of the invention, an oil reservoir is provided that is coupled to a housing of a vacuum pump. The oil reservoir comprises a cartridge that contains a lubricant to be supplied to the bearings of the vacuum pump. In particular, the cartridge contains a porous or fibrous material for containing and storing the lubricant. A supply tip is connected to the cartridge, in particular to a material in the cartridge, the supply tip also being made of a fibrous or porous material and configured to contact the oil supply nut of the vacuum pump. By means of this material, the lubricant is transported by capillary forces to the end of the tip and from there to the surface of the oil supply nut, whereby it is supplied to the bearings of the vacuum pump by the oil supply nut. Furthermore, in the invention, a backup bearing is arranged in the cartridge, the backup bearing being configured to accommodate the bearing journal element of the vacuum pump. The oil reservoir thus provides two functionalities, namely the function of containing and supplying the lubricant to the oil supply nut and the function of providing a backup bearing that interacts, in particular with the rotor shaft of the vacuum pump, in case of a failure.

[0013] Preferably, the backup bearing is constructed as a roller bearing, such as a ball bearing, or a friction bearing, or the like.

[0014] Preferably, the oil reservoir is releasably coupleable to the vacuum pump so that the oil reservoir can be replaced during maintenance of the vacuum pump to ensure a sufficient amount of lubricant in the oil reservoir and sufficient contact between the feed tip and the oil feed nut of the vacuum pump.

[0015] Preferably, the oil reservoir is further developed in conjunction with the inventions filed in EP Publication No. 3256733 and EP Publication No. 3494308.

[0016] In a third aspect of the invention, a kit is provided comprising the oil supply nut as described above and the oil reservoir as described above, for retrofitting to an existing vacuum pump. In particular, the bearing journal elements provided by the oil supply nut interact with a backup bearing located in the cartridge of the oil reservoir. Thus, the kit according to the invention allows the oil supply nut and the oil reservoir to be retrofitted to an existing vacuum pump during maintenance without major intrusion into the vacuum pump. Retrofitting an existing vacuum pump with the invention is: 1. Remove the existing oil reservoir, 2. Remove the existing oil supply nut from the vacuum pump; 3. Installing an oil supply nut according to the present invention; 4. Assembling an oil reservoir according to the present invention; Includes.

[0017] Thus, backup bearings are used in existing vacuum pumps to support the rotor shaft in the event of a vacuum pump failure and to prevent collisions of rotating elements within the vacuum pump that would otherwise result in significant damage or even destruction of the vacuum pump.

[0018] In a fourth aspect of the invention, a vacuum pump, in particular a turbomolecular pump, is provided, comprising a housing. A rotor shaft with at least one pump element is arranged in the housing, the rotor shaft being rotatably supported by one or more bearings. In this case, the at least one bearing is constructed as a roller bearing, such as a ball bearing. Furthermore, the vacuum pump comprises an oil reservoir as described above, preferably releasably coupled to the housing and containing a lubricant to be supplied to the at least one roller bearing. Furthermore, an oil supply nut is coupled to the rotor shaft. In that case, preferably, the oil supply nut is coupled to one end of the rotor shaft. The oil supply nut comprises an oil supply element extending axially between a first end and a second end of the oil supply nut. In that case, the oil supply element has a conical shape with an increasing diameter towards the second end, so as to create a large rotational force acting on the lubricant to convey the lubricant towards the second end. Preferably, the second end is arranged at the position of the roller bearing, i.e. at least a part of the roller bearing surrounds the second end of the oil supply nut. The lubricant is centrifugal force acting from the second end towards the roller bearing of the vacuum pump, supplying the lubricant for proper operation of the roller bearing. Further, according to the present invention, a bearing journal element is provided which is coupled to the oil supply nut and has a cylindrical surface adapted to be accommodated in a backup bearing arranged in a cartridge of the oil reservoir. Thus, the oil supply nut provides a bearing journal element for the backup bearing. Alternatively, the bearing journal element is directly coupled to the rotor shaft and has a cylindrical surface adapted to be accommodated in a backup bearing of the oil reservoir as well. Preferably, the bearing journal element is integrally formed with the rotor shaft. Thus, the rotor shaft itself constitutes a bearing journal which interacts with the backup bearing of the oil reservoir.

[0019] Preferably, the oil supply nut has a throughbore extending therethrough from a first end to a second end configured to receive at least a portion of a rotor shaft of the vacuum pump, the rotor shaft thus extending through the oil supply nut. A bearing journal element is preferably disposed at the first end of the oil supply nut for interaction with a backup bearing of the oil reservoir.

[0020] Preferably, the oil supply nut may be constructed according to the features as described above.

[0021] Preferably, the rotor shaft has a first end facing the outlet of the vacuum pump and an opposite second end facing the inlet of the vacuum pump, and the oil supply nut is coupled to the first end of the rotor shaft, in which case the oil supply nut can be coupled to the rotor shaft at the first end or directly coupled to the first end of the rotor shaft in direct contact therewith.

[0022] Preferably, the oil reservoir surrounds the first end of the rotor shaft such that the oil reservoir can interact with an oil supply nut coupled to the first end of the rotor shaft, while the bearing journal element can interact with a backup bearing for the oil reservoir.

[0023] Preferably, the cylindrical surface of the bearing journal element has a diameter smaller than the inner diameter of the backup bearing, so that the cylindrical surface of the bearing journal element does not contact the backup bearing during normal operation of the vacuum pump, and only in the event of a vacuum pump failure does the cylindrical surface of the bearing journal element contact the bearing to support the rotor shaft.

[0024] The present invention will now be described in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a vacuum pump according to the present invention. [Diagram 2]FIG. 2 shows a detailed view of the oil supply nut according to the invention. [Diagram 3] 2 shows a second embodiment of an oil supply nut according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 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 arranged with one or more pump elements 20 interacting with a stator element 22 of the housing 12. In the example of FIG. 1, the vacuum pump 10 is a turbomolecular vacuum pump, the pump elements 20 being constructed by vanes interacting with vanes of the stator element 22. The rotor shaft 18 is rotated by an electric motor 24, and the rotation of the rotor shaft 18 transports the gaseous medium from the inlet 14 to the outlet 16. There, the rotor shaft 18 is rotatably supported at the inlet 14 side of the vacuum pump 10 by a first bearing 26 constructed as a magnetic bearing. A second bearing supporting the rotor shaft 18 is constructed as a 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.

[0027] To the first end 30 of the rotor shaft 18 is coupled an oil feed nut 34, shown in detail in FIG. 2, having a first end 38 and an opposite second end 39. The oil feed nut 34 then comprises an oil feed element 36 having an outer surface that increases towards the second end 39 of the oil feed element 34. The oil feed element 36 therefore has a conical outer surface. Furthermore, the oil feed nut 34 is at least partially surrounded by an oil reservoir 40 that is releasably coupled to the housing 12 of the vacuum pump. In particular, the oil reservoir 40 is inserted into a recess in the housing 12 to allow easy access to the oil reservoir 40 during maintenance of the vacuum pump. The oil reservoir 40 comprises a cartridge 42 that contains and stores the lubricant to be supplied to the ball bearings 28. The cartridge 42 can then be filled with a fibrous or porous material to store the lubricant. To this material is connected a feed tip 44 that contacts the conical surface of the oil feed element 36 of the oil feed nut 34. The feed tip, preferably also made of a fibrous or porous material, draws the lubricant from the cartridge 42 by capillary forces and applies the lubricant to the surface of the oil feed element 36 of the oil feed nut. The oil feed nut 34 rotates together with the rotor shaft 18. Rotation of the oil feed nut by the vacuum pump shaft 18 carries the lubricant by centrifugal forces towards the ball bearings 28, with the second end of the oil feed nut 34 being in or within the range of the ball bearings 28. Thus, the lubricant is carried from the feed tip 44 through the oil feed element 36 to the second end of the oil feed element 34, from where it drips onto the ball bearings 28 of the vacuum pump 10.

[0028] 2, the oil supply nut 34 further comprises a bearing journal element 46 having a cylindrical outer peripheral surface. The bearing journal element 46 interacts with a backup bearing 48 disposed within the cartridge 42 of the oil reservoir 40. The backup bearing 48 can then be constructed as a ball bearing, a friction bearing, or the like. In that case, during normal operation of the vacuum pump, the bearing journal element 46 of the oil supply nut 34 does not contact the backup bearing 48 because the diameter of the bearing journal 46 is smaller than the inner diameter of the backup bearing 48. In the event of a vacuum pump failure, the bearing journal element 46 contacts the backup bearing 48, providing minimal support for the rotor shaft 18.

[0029] Since the backup 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 an existing vacuum pump with a backup bearing. Thus, in a first step, the old oil reservoir is removed. In a second step, the old oil supply nut is also removed. In a third step, a new oil supply nut, for example as shown in FIG. 2, with a bearing journal element 46 is installed on the first end 30 of the rotor shaft 18. In a fourth step, an oil reservoir according to the invention is installed, including a backup bearing 48 which interacts with the bearing journal element 46 of the oil supply nut 34.

[0030] 3 illustrates another embodiment, where the same or similar elements are designated with the same reference numerals. In this case, the oil supply nut 34 includes a throughbore 50 extending therethrough. The throughbore 50 is configured to receive a portion of the rotor shaft 18, the first end 30 of which extends through the oil supply nut 34 to provide a bearing journal element 52. Thus, the backup bearing interacts with the bearing journal element provided by the rotor shaft 18 itself to facilitate concentricity.

[0031] Thus, the present invention provides a combined system for supplying lubricant to the ball bearings of a vacuum pump and also providing a backup bearing, thereby avoiding significant damage or even destruction of the vacuum pump. Furthermore, a kit including the oil supply nut according to the present invention and the oil reservoir according to the present invention allows existing vacuum pumps to be easily retrofitted to provide the increased safety of a backup bearing. [Explanation of symbols]

[0032] 10 Vacuum Pump 12. Housing 14 Entrance 16 Exit 18 Rotor shaft 20 Rotor elements 22 Stator elements 24 Electromotor 26 Magnetic bearings 28 Ball Bearings 30 First end 32 Second end 34 Oil supply nut 36 Oil supply element 38 First end 39 Second end 40 Oil Reservoir 42 Cartridge 44 Supply Chip 46 Bearing journal elements 48 Backup bearing 50 Through hole 52 Bearing journal elements

Claims

1. 1. An oil reservoir configured to be coupled to a housing of a vacuum pump, comprising: a cartridge containing a lubricant to be supplied to the bearings of the vacuum pump; a supply tip that contacts an oil supply nut of the vacuum pump and applies a lubricant to a surface of the oil supply nut; a backup bearing disposed within the cartridge and configured to accommodate a bearing journal element of the vacuum pump; An oil reservoir comprising:

2. The oil reservoir of claim 1 , wherein the oil reservoir is releasably coupled to the vacuum pump.

3. A kit comprising an oil supply nut and an oil reservoir according to claim 1 or 2, adapted to be retrofitted to a vacuum pump, the oil supply nut is for supplying lubricant to a bearing of a vacuum pump; a first end and an opposing second end configured to couple to a shaft of the vacuum pump; an oil feed element extending between the first end and the second end, the oil feed element having an increasing diameter toward the second end to create a large rotational force acting on the lubricant to carry the lubricant toward the second end; and a bearing journal element having a cylindrical surface configured to be received in a backup bearing of the vacuum pump; A kit comprising:

4. A vacuum pump, in particular a turbomolecular pump, Housing and A rotor shaft disposed within the housing; an oil reservoir as claimed in claim 1 or 2 coupled to the housing; an oil feed nut coupled to the rotor shaft, the oil feed nut including an oil feed element extending between a first end and a second end of the oil feed nut, the oil feed element having an increasing diameter toward the second end to create a large rotational force acting on the lubricant to carry it toward the second end; a bearing journal element coupled to the oil supply nut or the rotor shaft and having a cylindrical surface configured to be received in the backup bearing of the oil reservoir; A vacuum pump comprising:

5. 5. The vacuum pump of claim 4, wherein the rotor shaft has a first end toward an outlet of the vacuum pump and an opposite second end toward an inlet of the vacuum pump, the oil supply nut being coupled to the first end of the rotor shaft.

6. The vacuum pump of claim 5 , wherein the oil reservoir surrounds the first end of the rotor shaft.

7. 7. A vacuum pump according to claim 4, wherein the cylindrical surface of the bearing journal element has a diameter smaller than an inner diameter of the backup bearing such that the cylindrical surface does not contact the backup bearing during normal operation of the vacuum pump.

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