Oil feed nut and oil reservoir for a vacuum pump

Abstract

An oil supply nut for providing lubricant to a bearing of a vacuum pump includes a first end and an opposite second end and is configured to be connected to a shaft of the vacuum pump. Further, the oil supply nut includes an oil supply element extending between the first end and the second end, wherein the oil supply element has an increasing diameter toward the second end to create an increasing rotational force on the lubricant to transport 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. Wherein the backup bearing is arranged in a cartridge of an oil reservoir.

Description

TECHNICAL FIELD

[0001] The present invention relates to an oil feed nut for providing lubricant to a bearing of a vacuum pump, to an oil reservoir for containing and providing lubricant, to a kit having such an oil feed nut and oil reservoir to be retrofitted to an existing vacuum pump, and to a vacuum pump having such an oil feed nut and oil reservoir. BACKGROUND

[0002] Existing vacuum pumps and in particular turbomolecular pumps such as US 10,400,777 and EP 3575610 comprise a housing having an inlet and an outlet. A rotor shaft is rotatably arranged within the housing, the rotor shaft having at least one pump element interacting with at least one stator element. The rotor shaft is rotated by an electric motor and due to the interaction of the at least one pump element with the at least one stator element, a gaseous medium is transported from the inlet to the outlet of the vacuum pump. For being rotatable, the rotor shaft is supported by one or more bearings, which can be roller bearings such as ball bearings or the like.

[0003] In operation, lubricant has to be delivered to the roller bearings in order to reduce wear and fatigue of the roller bearings. Typically, the lubricant is contained in an oil reservoir and delivered from the oil reservoir to the roller bearings by an oil feed nut. Therein, the oil reservoir needs to be replaced from time to time during maintenance of the vacuum pump in order to provide proper functioning and to ensure sufficient delivery of lubricant to the roller bearings.

[0004] Due to the fast rotation of the rotor shaft in case of a malfunction of the vacuum pump, the rotor shaft and in particular the pump element can be pressed into the stator, causing severe damage and even destruction of the vacuum pump and can further even pose a risk of injury to an operator. Therefore, it is desirable to have a backup bearing in the vacuum pump as described in DE 19729450 in order to support the rotor shaft in case of a malfunction and to avoid a pressing of the rotor and the housing or stator element. However, it is difficult to place both the backup bearing and the oil reservoir together with the oil feed nut. Due to the necessity of lubricating the roller bearings, the backup bearing is often omitted. In particular, for existing vacuum pumps without a backup bearing, it is currently almost impossible to retrofit a backup bearing in order to enhance the operational safety of the vacuum pump. SUMMARY

[0005] It is therefore an object of the present invention to provide the possibility of having both an oil feed nut and a backup bearing and further to provide the possibility of retrofitting an existing vacuum pump with such a backup bearing without a large intervention into the vacuum pump.

[0006] The problem given above is solved by the present invention by the oil feed nut, the oil reservoir, the kit comprising such an oil feed nut and such an oil reservoir, and the vacuum pump.

[0007] In a first aspect of the invention, a lubrication nut is provided for supplying lubricant to a bearing of a vacuum pump. The lubrication nut includes a first end and an opposing second end and is configured to connect to the rotor shaft of the vacuum pump. Specifically, the lubrication nut is releasably connected to the rotor shaft of the vacuum pump. Further, the lubrication nut includes a lubrication element extending axially between the first and second ends of the lubrication nut, wherein the lubrication element has an increased diameter toward the second end to be conical. Due to the increased diameter, an increased rotational force acts on the lubricant on the surface of the lubrication element, thereby delivering lubricant toward the second end and from the second end to a bearing of the vacuum pump located near the second end of the lubrication nut. According to the invention, the lubrication nut includes a bearing journal element having a cylindrical surface and is configured to be received in a spare bearing of the vacuum pump. Therefore, through this invention, the oil supply nut provides two functions in combination: delivering lubricant from the oil reservoir to the bearing via the oil supply element and further providing a bearing journal element that interacts with the spare bearing of the vacuum pump to support the rotor shaft of the vacuum pump in the event of a vacuum pump failure. Thus, these functions are integrated into a single component, which 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 a single component. Even more preferably, the oil supply nut is constructed as a single component.

[0009] The bearing journal element is located at the first end of the oil supply nut, and the oil supply element is located at the second end. More specifically, the bearing journal element is directly adjacent to the oil supply element.

[0010] Preferably, the oil supply nut includes a connecting element to be connected to the rotor shaft of the vacuum pump. Therefore, the connecting element facilitates the connection between the oil supply nut and the rotor shaft of the vacuum pump. Specifically, the connecting element releasably connects the oil supply nut to the rotor shaft. In both cases, the connecting element can be provided via a threaded connection, shrink fit, clamping, etc.

[0011] Preferably, the connecting element is disposed at the second end. Alternatively, the oil supply nut includes a through hole extending from the first end through the oil supply nut to the second end and configured to receive part of the rotor shaft of the vacuum pump, wherein the connecting element is disposed at the first end, and the oil supply nut can be connected to the rotor shaft when the connecting element is located at the first end. Due to the through hole, the oil supply nut surrounds the rotor shaft, thereby improving the concentricity of the rotor shaft and the oil supply nut.

[0012] In a second aspect of the invention, an oil reservoir is provided for connection to the housing of a vacuum pump. The oil reservoir includes a cartridge containing lubricant to be supplied to the bearings of the vacuum pump. Specifically, the cartridge contains a porous or fibrous material for containing and storing the lubricant. A feeding tip is connected to the cartridge and, particularly, to the material within the cartridge, wherein the feeding tip is also made of fibrous or porous material and configured to contact the oil supply nut of the vacuum pump. Due to this material, lubricant is delivered to the end of the tip and, due to capillary force, from the end of the tip to the surface of the oil supply nut and supplied to the bearings of the vacuum pump via the oil supply nut. Further, according to the invention, a spare bearing is arranged in the cartridge, wherein the spare bearing is configured to receive the bearing journal element of the vacuum pump. Thus, the oil reservoir provides two functions in combination: containing and delivering lubricant to the oil supply nut, and further providing a spare bearing, particularly interacting with the rotor shaft of the vacuum pump, in the event of a failure.

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

[0014] Preferably, the oil reservoir can be releasably connected to the vacuum pump. Therefore, the oil reservoir can be replaced during vacuum pump maintenance to ensure sufficient lubricant in the reservoir and adequate contact between the vacuum pump's feed tip and the oil supply nut.

[0015] Preferably, the oil reservoir is further developed in conjunction with inventions such as those filed according to EP3256733 and EP3494308.

[0016] A third aspect of the invention provides a kit comprising a previously described oil supply nut and a previously described oil reservoir to be retrofitted to an existing vacuum pump. Specifically, a bearing journal element supplied by the oil supply nut interacts with a spare bearing housed in the cylinder of the oil reservoir. Therefore, due to the kit according to the invention, the oil supply nut and oil reservoir can be retrofitted to an existing vacuum pump during maintenance without significant intervention to the vacuum pump. Retrofitting an existing vacuum pump with the present invention includes the following steps:

[0017] 1. Remove the existing oil reservoir.

[0018] 2. Remove the existing oil supply nut from the vacuum pump.

[0019] 3. Install the oil supply nut according to the present invention, and

[0020] 4. Assemble the oil reservoir according to the present invention.

[0021] Therefore, a spare bearing is used in existing vacuum pumps. This spare bearing supports the rotor shaft and prevents collisions between rotating components inside the vacuum pump in the event of a vacuum pump failure, which would otherwise lead to serious damage or even destruction of the vacuum pump.

[0022] In a fourth aspect of the invention, a vacuum pump, particularly a turbomolecular pump, is provided, comprising a housing. A rotor shaft is disposed within the housing, the rotor shaft having at least one pumping element, wherein the rotor shaft is rotatably supported by one or more bearings. The at least one bearing is constructed as a roller bearing, such as a ball bearing. Further, the vacuum pump includes an oil reservoir as previously described, which is preferably releasably connected to the housing and contains lubricant to be supplied to the at least one roller bearing. Further, an oil supply nut is connected to the rotor shaft. Preferably, the oil supply nut is connected to one end of the rotor shaft. The oil supply nut includes an oil supply element extending axially between a first end and a second end of the oil supply nut. The oil supply element has an increased diameter toward the second end to be conical, thereby generating an increased rotational force acting on the lubricant to deliver the lubricant toward the second end. Preferably, the second end is arranged at the location of the roller bearing, i.e., at least a portion of the roller bearing surrounds the second end of the oil supply nut. The lubricant is propelled from the second end toward the roller bearing of the vacuum pump by centrifugal force, thereby providing lubrication for the proper operation of the roller bearing. Further, according to the invention, a bearing journal element connected to the oil supply nut is provided, having a cylindrical surface and configured to be received in a spare bearing housed in the cylinder of an oil reservoir. Thus, the oil supply nut provides a bearing journal element for the spare bearing. Alternatively, the bearing journal element is directly connected to the rotor shaft, which also has a cylindrical surface and is configured to be received in the spare bearing of the oil reservoir. Preferably, the bearing journal element is integrally formed as a single component by the rotor shaft. Thus, the rotor shaft itself includes a bearing journal that interacts with the spare bearing of the oil reservoir.

[0023] Preferably, the oil supply nut has a through-hole extending from a first end through the oil supply nut to a second end, the through-hole being configured to receive at least a portion of the rotor shaft of the vacuum pump. Thus, the rotor shaft extends through the oil supply nut. The bearing journal element is preferably arranged at the first end of the oil supply nut to enable interaction with the spare bearing of the oil reservoir.

[0024] Preferably, the oil supply nut can be constructed according to the features described above.

[0025] Preferably, the rotor shaft includes a first end facing the outlet of the vacuum pump and a opposing second end facing the inlet of the vacuum pump, wherein an oil supply nut is connected to the first end of the rotor shaft. The oil supply nut can be connected to the rotor shaft at the first end, or directly to the first end of the rotor shaft, thereby making direct contact with the first end of the rotor shaft.

[0026] Preferably, the oil reservoir surrounds the first end of the rotor shaft. Thus, the oil reservoir can interact with the oil supply nut connected to the first end of the rotor shaft, while the bearing journal element can interact with the spare bearing in the oil reservoir.

[0027] Preferably, the cylindrical surface of the bearing journal element has a diameter smaller than the inner diameter of the spare bearing, so that during normal operation of the vacuum pump, the cylindrical surface of the bearing journal element does not contact the spare bearing. Only in the event of a vacuum pump failure will the cylindrical surface of the bearing journal element contact the bearing to provide support for the rotor shaft. Attached Figure Description

[0028] The invention is described in more detail below with reference to the accompanying drawings.

[0029] It is shown that:

[0030] Figure 1 The vacuum pump according to the present invention,

[0031] Figure 2 This is a detailed view of the oil supply nut according to the present invention, and

[0032] Figure 3 This is a second embodiment of the oil supply nut according to the present invention. Detailed Implementation

[0033] The vacuum pump 10 includes a housing 12 having an inlet 14 and an outlet 16. A rotor shaft 18 is disposed within the housing 12, and the rotor shaft has one or more pump elements 20 that interact with the stator elements 22 of the housing 12. Figure 1 In the example, vacuum pump 10 is a turbomolecular vacuum pump, wherein pump element 20 is constructed of blades that interact with blades of stator element 22. Rotor 18 is rotated by electric motor 24 and, due to the rotation of rotor shaft 18, gaseous medium is conveyed from inlet 14 to outlet 16. Rotor 18 is rotatably supported by a first bearing 26, which is constructed as a magnetic bearing at the inlet 14 side of vacuum pump 10. A second bearing supporting rotor shaft 18 is constructed as a ball bearing 28 at the outlet side of rotor shaft 18, which is located at a first end 30 of rotor shaft 18 (opposite to a second end 32 of rotor shaft 18).

[0034] The oil supply nut 34 is connected to the first end 30 of the rotor shaft 18. Figure 2As shown in more detail, the oil supply nut 34 has a first end 38 and an opposing second end 39. The oil supply nut 34 includes an oil supply element 36, the outer surface of which has a portion that increases toward the second end 39. Therefore, the oil supply element 36 has a conical outer surface. Further, the oil supply nut 34 is at least partially surrounded by an oil reservoir 40, which is releasably connected to the housing 12 of the vacuum pump. Specifically, the oil reservoir 40 is inserted into a recess in the housing 12 to provide easy access to the oil reservoir 40 during maintenance of the vacuum pump. The oil reservoir 40 includes a cylinder 42 that contains and stores lubricant to be supplied to the ball bearing 28. The cylinder 42 can be filled with a fibrous or porous material to store the lubricant. A feed tip 44 is connected to this material and contacts the conical surface of the oil supply element 36 of the oil supply nut 34. Preferably, the feed tip is also made of fiber or porous material, thereby drawing lubricant from the cylinder 42 via capillary force and applying the lubricant to the surface of the oil supply element 36 of the oil supply nut. The oil supply nut 34 rotates together with the rotor shaft 18. As the oil supply nut rotates via the shaft 18 of the vacuum pump, the lubricant is delivered towards the ball bearing 28 by centrifugal force, wherein the second end of the oil supply nut 34 is within or within the ball bearing 28. Thus, the lubricant is delivered from the feed tip 44 to the second end of the oil supply element 34 via the oil supply element 36 and drips from there onto the ball bearing 28 of the vacuum pump 10.

[0035] Furthermore, such as Figure 2 As shown, the oil supply nut 34 further includes a bearing journal element 46 with a cylindrical outer surface. The bearing journal element 46 interacts with a spare bearing 48 disposed in the cylinder 42 of the oil reservoir 40. The spare bearing 48 can be constructed as a ball bearing, friction bearing, etc. During normal operation of the vacuum pump, the bearing journal element 46 of the oil supply nut 34 does not contact the spare bearing 48 because the diameter of the bearing journal 46 is smaller than the inner diameter of the spare bearing 48. In the event of a vacuum pump failure, the bearing journal element 46 contacts the spare bearing 48 and provides minimal support for the rotor shaft 18.

[0036] Since the spare 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 the spare bearing to an existing vacuum pump. Therefore, in the first step, the old oil reservoir is removed. Secondly, the old oil supply nut is also removed. Thirdly, as for example in Figure 2 The new oil supply nut, which has a bearing journal element 46, is shown mounted on the first end 30 of the rotor shaft 18. Fourth, an oil reservoir according to the invention is installed, which includes a spare bearing 48 that interacts with the bearing journal element 46 of the oil supply nut 34.

[0037] Figure 3Another embodiment is shown, wherein the same or similar elements are indicated by the same reference numerals. In this embodiment, the oil supply nut 34 includes a through-hole 50 extending through the oil supply nut 34. The through-hole 50 is configured to receive a portion of the rotor shaft 18 such that a first end 30 of the rotor shaft 18 extends through the oil supply nut 34 and provides a bearing journal element 52. Thus, the spare bearing interacts with the bearing journal element provided by the rotor shaft 18 itself to achieve concentricity.

[0038] Therefore, the present invention provides a combined system that supplies lubricant to the ball bearings of a vacuum pump and further provides a spare bearing, thereby preventing serious damage or even destruction of the vacuum pump. Furthermore, existing vacuum pumps can be easily retrofitted to provide increased safety through the spare bearing by means of a kit including an oil supply nut according to the invention and an oil reservoir according to the invention.

[0039] 10 vacuum pumps

[0040] 12 shells

[0041] 14 entrances

[0042] 16 Exports

[0043] 18 rotor shafts

[0044] 20 rotor elements

[0045] 22 stator elements

[0046] 24 electric motors

[0047] 26 magnetic bearings

[0048] 28 ball bearings

[0049] 30 First End

[0050] 32 Second End

[0051] 34 Oil Supply Nut

[0052] 36 oil supply elements

[0053] 38 First End

[0054] 39 Second End

[0055] 40 oil reservoir

[0056] 42 tubes

[0057] 44 Feed tip

[0058] 46 bearing journal element

[0059] 48 spare bearings

[0060] 50 through hole

[0061] 52 bearing journal element

Claims

1. An oil reservoir (40) configured to be connected to the housing of a vacuum pump, the oil reservoir comprising: Cylinder (42), the cylinder (42) containing lubricant to be supplied to the bearings of the vacuum pump, The feed tip (44) is to contact the oil supply nut of the vacuum pump to apply the lubricant to the surface of the oil supply nut, and A spare bearing (48) is arranged in the cylinder (42), the spare bearing (48) being configured to receive the bearing journal element of the vacuum pump.

2. The oil reservoir according to claim 1, characterized in that, The oil reservoir can be releasably connected to the vacuum pump.

3. A kit comprising an oil supply nut (34) and an oil reservoir (40) according to claim 1 or 2, wherein, The oil supply nut (34) includes: a first end (38) and an opposing second end (39) configured to be connected to the shaft of the vacuum pump; an oil supply element (36) extending between the first end (38) and the second end (39), wherein the oil supply element (36) has an increased diameter toward the second end (39) to generate an increased rotational force acting on the lubricant in order to deliver the lubricant toward the second end (39); and a bearing journal element (46) having a cylindrical surface configured to be received in the spare bearing (48).

4. The kit according to claim 3, characterized in that, The bearing journal element (46) is arranged at the first end (38), and the oil supply element (36) is arranged at the second end (39).

5. The kit according to claim 3 or 4, characterized in that, The oil supply nut (34) includes a connecting element to be connected to the rotor shaft of the vacuum pump.

6. The kit according to claim 5, characterized in that, The connecting element is arranged at the second end (39).

7. The kit according to claim 5, characterized in that, The oil supply nut (34) includes a through hole (50) extending from the first end (38) through the oil supply nut to the second end (39) and configured to receive the rotor shaft of the vacuum pump, wherein the connecting element is arranged at the first end.

8. A vacuum pump (10) comprising: Shell (12) The rotor shaft (18) is disposed in the housing (12). The oil reservoir (40) according to any one of claims 1 or 2 is connected to the housing (12). The oil supply nut (34) is connected to the rotor shaft (18). The oil supply nut (34) includes an oil supply element (36) extending between a first end (38) and a second end (39) of the oil supply nut (34). The oil supply element (36) has an increased diameter toward the second end (39) to generate an increased rotational force acting on the lubricant, so as to deliver the lubricant toward the second end (39). The bearing journal element (46), which is connected to the oil supply nut (34) or the rotor shaft (18), has a cylindrical surface and is configured to be received in the spare bearing (48) in the oil reservoir (40).

9. The vacuum pump according to claim 8, characterized in that, The rotor shaft (18) includes a first end facing the outlet of the vacuum pump and a second end facing the inlet of the vacuum pump, wherein the oil supply nut (34) is connected to the first end of the rotor shaft (18).

10. The vacuum pump according to claim 9, characterized in that, The oil reservoir (40) surrounds the first end of the rotor shaft (18).

11. The vacuum pump according to any one of claims 8 to 10, characterized in that, The cylindrical surface of the bearing journal element (46) has a smaller diameter than the inner diameter of the spare bearing (48) such that the cylindrical surface does not contact the spare bearing (48) during normal operation of the vacuum pump.

12. The vacuum pump according to any one of claims 8 to 10, characterized in that, The vacuum pump is a turbomolecular pump.

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