Vacuum pump

Abstract

The invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with at least one pumping stage which comprises a stator and a rotor which, during operation, rotates relative to the stator about an axis of rotation, a bearing, in particular a rolling bearing, for the rotor, and a lubricating device for lubricating the bearing with a liquid lubricant, wherein the lubricating device comprises an annular or partially annular transfer element which runs around the axis of rotation and receives lubricant coming from the bearing and delivers it to a return device of the lubricating device, wherein the transfer element surrounds the bearing and / or wherein the transfer element engages radially or with a radial component in a passage section surrounding the bearing, through which passage section lubricant can pass from the bearing to the transfer element.

Description

[0001] The invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, with at least one pumping stage comprising a stator and a rotor rotating about an axis of rotation relative to the stator during operation, a bearing, in particular a rolling bearing, for the rotor, and a lubricating device for lubricating the bearing with a liquid lubricant, wherein the lubricating device comprises an annular or partially annular transfer element extending around the axis of rotation, which receives lubricant coming from the bearing and delivers it to a return device of the lubricating device.

[0002] Such vacuum pumps are generally known, for example from EP 3 597 926 A1 and EP 3 106 691 A1. The transfer element, designed as a felt ring, for example, serves to collect lubricant coming from the bearing when the vacuum pump is upside down. Many vacuum pumps are basically capable of operating in all positions, i.e. they can be operated upright, upside down, in an inclined position and, in particular, lying on their side. This capability in all positions increases the demands on the lubrication of the bearing. The lubricant is supplied, for example, via a conical section of the rotor and is independent of the orientation of the vacuum pump in space. The removal of the lubricant from the bearing, on the other hand, requires special measures if the vacuum pump is not to be operated exclusively in an upright position.The removal of the lubricant is important to avoid any impairment of the bearing's functionality, particularly due to lubricant accumulation in and on the bearing.

[0003] In the context of the present disclosure, "upright" means that the rotor's axis of rotation extends vertically and the at least one pumping stage is located above the bearing. "Lying" operation is therefore referred to when the rotor's axis of rotation extends horizontally. When "top" and "bottom" are mentioned, this refers to an upright pump.

[0004] The term "rotor" refers to the entirety of the rotating components of the vacuum pump. A distinction is often made between the rotor shaft on the one hand and other components attached to the rotor shaft or formed integrally with it on the other. The bearing then serves as the rotary support for the rotor shaft.

[0005] The term "bearing mount" is often used for an assembly that accommodates the bearing and, in particular, supports it radially and axially. The components belonging to the lubrication system are usually considered part of the bearing mount.

[0006] In known lubrication systems for vacuum pumps, a felt ring is located above the bearing. This arrangement requires a comparatively large axial height, but is structurally relatively simple and enables good lubricant return when the vacuum pump is upside down. The return is usually achieved via a plurality of return rods distributed around the circumference and made of a material that has a capillary effect on the respective lubricant. These return rods connect the felt ring to a lubricant reservoir in the lower area of ​​the vacuum pump. However, such felt rings arranged above the bearing are often useless with regard to lubricant return when the pump is operated horizontally, since in this orientation at most a small amount of lubricant, which due to gravity can only reach one or two of the return rods located below, can be returned to the lubricant reservoir via these.

[0007] From the above-mentioned EP 3 597 926 A1 (Figs. 12 and 14), a lubrication device is known in which a felt ring is arranged in a component positioned above the bearing. This felt ring, together with another component surrounding the bearing, forms an annular gap through which lubricant can flow from the bearing to the felt ring. Lubricant return is also possible here with the vacuum pump positioned on its side. However, this arrangement requires a comparatively large axial height and a relatively large number of components, since the lubricant must flow to the felt ring through the aforementioned radial gap between the two axially superimposed components.

[0008] The object of the invention is to improve a vacuum pump of the type mentioned at the outset with regard to the lubrication device and in particular the return of lubricant in such a way that, regardless of the orientation of the vacuum pump in space, the lubricant can be reliably removed from the bearing and fed to a return device, wherein the assembly accommodating the bearing and the lubrication device should have the smallest possible axial height.

[0009] This problem is solved by the features of independent claim 1.

[0010] According to a first aspect of the invention, the transfer element surrounds the bearing. Relative to the axial direction defined by the rotor's axis of rotation, the transfer element is thus not located above the bearing, but at the same height as the bearing. The transfer element and the bearing can overlap each other, so that the transfer element surrounds the bearing with part of its axial height. Alternatively, the transfer element can surround the bearing over its entire axial height, i.e., the bearing protrudes beyond the transfer element on both sides.

[0011] By surrounding the bearing, the transfer element according to this first aspect of the invention allows the transfer element to reach close to the bearing in the radial direction. Consequently, the lubricant can be transported from the bearing in the radial direction, thus taking the shortest route to the transfer element. Furthermore, the transfer element surrounding the bearing saves axial height, as it is not necessary to arrange the transfer element above the bearing.

[0012] According to this first aspect of the invention, the transfer element can directly surround the bearing, i.e., there is no further component between the bearing and the transfer element in the radial direction. A radial gap can be present between the bearing and the transfer element. Alternatively, the transfer element can contact the bearing, in particular an outer ring of a bearing designed as a rolling bearing. In this case, the transfer element can contact the bearing with its entire circumference. Alternatively, the transfer element can contact the bearing at several discrete points distributed in the circumferential direction.

[0013] According to another development of the first aspect of the invention, a component which is designed in one or more parts can be present in the radial direction between the bearing and the transfer element. This component can be designed as a passage section or can comprise a passage section through which lubricant can pass from the bearing to the transfer element. The transfer element surrounds the bearing, i.e. the transfer element does not surround the bearing directly, but indirectly via the component. In this development, too, a radial gap can be present between the transfer element and the component. Alternatively, the transfer element can contact the component, either over its entire circumference or at several discrete points distributed in the circumferential direction.

[0014] According to a second aspect of the invention, it is provided that the transfer element engages radially or with a radial component in a passage section surrounding the bearing, through which lubricant can pass from the bearing to the transfer element.

[0015] In this second aspect of the invention, the transfer element can surround the bearing, i.e., be arranged axially at the level of the bearing, with the passage section located between the transfer element and the bearing. Alternatively, the transfer element can be arranged axially outside, i.e., above or below, the bearing. Regardless of whether the transfer element surrounds the bearing or is located axially outside the bearing, the engagement of the transfer element in the passage section surrounding the bearing can bring the transfer element closer to the bearing than without such engagement. The lubricant can thus travel a comparatively short distance from the bearing to the transfer element.

[0016] If the transfer element surrounds the bearing, i.e. is arranged axially at the level of the bearing, the lubricant can reach the transfer element via the shortest route in the radial direction through the passage section. Even if the transfer element is arranged above or below, i.e. axially outside, the bearing, the path that the lubricant has to travel from the bearing to the transfer element, for example on a straight path oblique to the axis of rotation, is shorter due to the engagement of the transfer element in the passage section than it would be without such engagement. Engagement in the passage section can occur axially outside the bearing or at the level of the bearing. A transfer element arranged above the bearing, for example, can engage in the passage section with projections extending obliquely to the axis of rotation, i.e. with a radial component. A projection formed in the passage section and leading from the bearing to the transfer element orThe lubricant passage leading to its projections can then run obliquely to the axis of rotation.

[0017] If the lubricant passage is designed as a circumferential slot, it is located in a conical surface with the axis of rotation as the central axis.

[0018] In this second aspect of the invention, the transfer element can engage the passage section over its entire circumference. Alternatively, the transfer element can engage the passage section at several discrete locations distributed circumferentially.

[0019] The transfer element and the passage section can be designed such that the passage section is mechanically weakened only to a comparatively small extent to allow the engagement of the transfer element. Despite the engagement of the transfer element, a high level of mechanical stability of the passage section can be ensured, which may also ensure a high level of mechanical stability and thus a high level of rigidity of a component comprising the passage section or, as a whole, of a bearing housing accommodating the bearing.

[0020] The return device can comprise a plurality of return elements arranged in a circumferential direction and extending axially or with an axial component, made of a material that acts as a capillary for the lubricant. In particular, the return device leads to a lubricant reservoir surrounding the lower end of the rotor. Such lubricant reservoirs are generally known and can, for example, comprise a stack of discs made of felt or another material capable of storing and conveying the lubricant.

[0021] If a passage section surrounding the bearing is present, then regardless of whether the transfer element merely surrounds the passage section according to a possible embodiment of the first aspect of the invention or engages in the passage section according to the second aspect of the invention, this can be a component of a component surrounding the bearing, which forms a bearing mount of the vacuum pump that accommodates the bearing or is a component of such a bearing mount. The component comprising the passage section can in particular be designed such that it also extends radially outside the passage section and in particular radially outside the transfer element. In particular, this component can serve to accommodate the transfer element, for example in a front-end recess of the component. This will be discussed in more detail elsewhere.

[0022] The transfer element can be annular, i.e., in the form of a closed ring. Alternatively, the transfer element can enclose an angle of less than 360°, for example, 270° or 300°. This may be necessary or advantageous if a specific angular range within the bearing area is to be used for other purposes where a closed-ring transfer element would be obstructive.

[0023] The transfer element can be constructed in one piece or in multiple parts. For example, two partial rings of 180° each or three partial rings of 120° each can together form a closed ring in the fully assembled state. Alternatively, two partial rings of 160° each or three partial rings of 100° each can together form a partially annular transfer element in the fully assembled state, extending over an angle of 320° or 300°, respectively.

[0024] The liquid lubricant is preferably an oil specifically tailored to the respective bearing. The bearing is, in particular, a rolling bearing, such as a ball bearing.

[0025] The vacuum pump is, in particular, a turbomolecular vacuum pump, whose pumping system comprising one or more pumping stages has a fundamentally known design. For example, the pump can have one or more turbomolecular pumping stages, followed by one or more Holweck pumping stages. The rotor includes the rotor disks of the turbomolecular pumping stages, each of which has a plurality of rotor blades, and the one or more Holweck hubs, as well as the Holweck sleeves of the Holweck pumping stages supported by these rotor disks.

[0026] Relative to the axial direction, the return device is located, in particular, on the side of the transfer element facing away from the at least one pumping stage. In particular, the return device leads downwards to a lubricant reservoir surrounding the free end of the rotor. The rotor bearing to be lubricated is thus located between the lubricant reservoir and the at least one pumping stage.

[0027] The two aspects of the invention can be combined with one another, so that the transfer element surrounds the bearing, i.e. is arranged axially at the height of the bearing, and engages in a passage section surrounding the bearing. This embodiment is characterized in that, with a low axial height and high mechanical stability, the transfer element reaches close to the bearing in the radial direction, thus ensuring reliable lubrication of the bearing, reliable removal of lubricant from the bearing so that no disruptive accumulation of lubricant occurs, and reliable return of the lubricant, and this is the case with any orientation of the vacuum pump in space, i.e., both with an upright vacuum pump, with overhead operation of the vacuum pump, and with an inclined or horizontal vacuum pump.

[0028] In principle, each of these advantages also applies to the two aspects of the invention taken individually.

[0029] Advantageous further developments of the invention are also specified in the dependent claims, the description and the drawing.

[0030] If nothing else is mentioned in connection with the passage section surrounding the bearing, this is to be understood as both a passage section which is merely surrounded by the transfer element and a passage section into which the transfer element engages radially or with a radial component, ie embodiments relating to the passage section then relate to both aspects of the invention.

[0031] At least one lubricant passage for the lubricant can be formed in the bearing and / or in a passage section surrounding the bearing. By means of such a passage, the lubricant can be discharged from the bearing in a defined manner.

[0032] According to some developments, it can be provided that the transfer element, on the one hand, and a lubricant outlet of a lubricant passage for the lubricant leading to the transfer element and extending radially or with a radial component, on the other hand, are axially aligned with one another.

[0033] In other words, the lubricant outlet is located in a plane perpendicular to the rotation axis, which intersects the transfer element. This allows the lubricant to reach the transfer element directly.

[0034] The lubricant passage may be formed in the bearing and / or extend through a passage section surrounding the bearing.

[0035] In particular, if the transfer element directly surrounds the bearing, i.e., if no passage section is provided between the bearing and the transfer element, the passage can be formed only in the bearing. For example, the passage can comprise one or more drainage holes distributed in the circumferential direction in the bearing, which are formed in particular in an outer ring of a rolling bearing forming the bearing.

[0036] If a passage section is present between the bearing and the transfer element, a lubricant outlet from the bearing can be axially aligned with a lubricant inlet of the lubricant passage formed in the passage section. In an advantageous embodiment, the lubricant passage runs radially through the bearing and through a passage section surrounding the bearing to the transfer element.

[0037] In particular, depending on the axial position of the transfer element relative to the bearing, the lubricant passage can run in a plane perpendicular to the axis of rotation. Alternatively, the lubricant passage can run obliquely to the axis of rotation, for example, when the transfer element is arranged above the bearing. In this case, the lubricant passage can be located in a conical surface with the axis of rotation as its central axis.

[0038] According to some developments, the lubricant passage can be formed circumferentially around the axis of rotation or can comprise a plurality of discrete individual passages distributed around the axis of rotation. For example, the lubricant passage can be a circumferential slot, which is formed, for example, in a passage section surrounding the bearing. If several individual passages are present, these can be provided in the form of discrete slots or bores. The slots or bores can run radially or obliquely to the axis of rotation, i.e. all individual passages can lie in a plane running perpendicular to the axis of rotation or in a conical surface having the axis of rotation as its central axis.

[0039] It is also possible for the lubricant passage to have differently designed individual passages, ie some individual passages can be designed as slots and some individual passages as holes.

[0040] According to some embodiments of the invention, the transfer element can have a plurality of projections distributed in the circumferential direction, projecting radially or with a radial component inward, in particular tapering toward their free end. The projections can be convexly curved, at least in the region of their free end.

[0041] With such projections, the transfer element can, for example, according to the second aspect of the invention, engage in a passage section surrounding the bearing. However, this is not mandatory. Even if the transfer element merely surrounds a passage section surrounding the bearing, the transfer element can have such projections pointing towards the passage section or touching the passage section. Such a configuration is also possible if no passage section is present, i.e., if the transfer element directly surrounds the bearing, in which case the projections are directed towards the bearing or touch the bearing.

[0042] The projections can be particularly advantageous when a lubricant passage of the passage section or the bearing has a plurality of discrete lubricant outlet openings distributed circumferentially, and the projections of the transfer element are aligned with these outlet openings in the circumferential direction. Targeted absorption of lubricant can then be achieved by means of the projections of the transfer element, in particular at least with convexly curved free ends of the projections.

[0043] If, according to the second aspect of the invention, the transfer element engages in a passage section surrounding the bearing, then according to some developments, it can be provided that recesses for the projections are formed in the passage section, into which the transfer element engages with its projections. In particular, it can be provided that intermediate sections of the passage section located between the recesses engage in spaces in the transfer element that exist between the projections.

[0044] In other words, in such a configuration, the transfer element has an internal toothing and the passage section has an external toothing engaging with this internal toothing, wherein the teeth of the transfer element are formed by the projections and the teeth of the passage section are formed by the intermediate sections.

[0045] Such a toothing between the transfer element and the passage section ensures a high mechanical stability of the passage section despite the engagement of the transfer element and at the same time ensures that the transfer element with its projections can reach comparatively close to the bearing in order to avoid long paths for the lubricant coming from the bearing.

[0046] According to some developments, the projections and the recesses can be configured to be at least substantially complementary to one another. This allows the lubricant to reach the projections over their entire circumference.

[0047] Furthermore, it can be provided that a lubricant passage formed in the passage section opens exclusively into the recesses. This can ensure that the lubricant only reaches the projections. This can be achieved in a particularly simple way from a manufacturing perspective if the lubricant passage is a circumferential slot extending radially from within the passage section or with a radial component outwards, which is dimensioned such that it opens into the recesses but ends within intermediate sections between the recesses. In other words, the passage section is cut into the inside but not completely severed. This makes it particularly simple from a manufacturing perspective to drain lubricant from the bearing by means of a one-piece passage section orby means of a one-piece component encompassing the passage section, which not only ensures reliable removal of lubricant but also high mechanical stability.

[0048] According to some embodiments of the invention, the return device may comprise a plurality of return elements arranged in a circumferential direction, in particular extending axially or with an axial component, which are in contact with the transfer element at discrete locations distributed around the axis of rotation.

[0049] The feedback elements can, for example, be provided in the form of rods.

[0050] The return elements are typically made of a material that allows the lubricant to move through capillary action. For example, the return elements are made of porous polyethylene (also known as poroplast). However, other materials can also be used for the return elements.

[0051] The return elements can be in contact with projections of the transfer element, with which the transfer element engages in a passage section surrounding the bearing. Lubricant previously absorbed by the transfer element can be discharged into the respective return element via the contact points, for example, between the underside of a projection of the transfer element and the upper end face of a return element.

[0052] Furthermore, it can be provided that the return elements extend from the transfer element through a component surrounding the bearing, in particular comprising the passage section.

[0053] As already mentioned above in another context, the passage section, in particular, can be a component of a one-piece component that extends radially outward beyond the passage section and accommodates the transfer element, for example, in a front-end recess. Starting from the recess, passages formed in this component can extend, in particular in the axial direction, and serve to accommodate the return elements.

[0054] According to some embodiments of the invention, it can be provided that the transfer element is received, in particular completely, in a front-side recess of a component surrounding the bearing, in particular comprising the passage section.

[0055] In particular, it can be provided that the transfer element and the recess are formed at least substantially complementary to one another.

[0056] Furthermore, according to some embodiments, it can be provided that a component surrounding the bearing, in particular comprising the passage section, is covered on the front side by a separate cover element.

[0057] It can be provided that the cover element covers a frontal recess of the component which receives the transfer element.

[0058] The cover element can have a cover section that has a smaller axial height than the transfer element. A cover element with such a relatively thin cover section can save axial height.

[0059] The cover element can be lid-shaped and can overlap the component with an edge section on the outside.

[0060] In particular, it can be provided that the cover element and the component are pressed together. This eliminates the need to screw the cover element and the component together. Screwing would require additional axial height to form a screw thread, which can be eliminated by the pressing provided in this embodiment.

[0061] According to further embodiments of the invention, it can be provided that a component surrounding the bearing, in particular encompassing the through-section and accommodating the transfer element, is formed in one piece. Such a component can form a bearing mount accommodating the bearing or a component of such a bearing mount.

[0062] Furthermore, it can be provided that a component surrounding the bearing, in particular encompassing the passage section, engages over the bearing at the front end with a collar section. In this way, the component can form an axial closure element by means of the collar section, in particular an axial closure element of an assembly encompassing the bearing, in particular a bearing housing.

[0063] Furthermore, it can be provided that the component has a front-side recess which receives the transfer element and which lies radially outside the collar section.

[0064] Furthermore, according to some embodiments, the collar portion that engages the bearing at the front end can protrude axially through an opening formed in a separate cover element that covers the component at the front end. The cover element can form an upper axial closure of the assembly comprising the bearing, thereby realizing a relatively low axial height that is only increased where the collar portion that engages the bearing at the front end protrudes through the opening.

[0065] According to some developments of the invention, a component surrounding the bearing, in particular encompassing the passage section, is at least approximately cup-shaped. In particular, it can be provided that a recess accommodating the transfer element is formed on the outer side of a base section of the component. This recess surrounds a collar section of the component that overlaps the bearing at the front end and from which several passages distributed in the circumferential direction extend, through which return elements of the return device extend from the transfer element to a lubricant reservoir of the lubrication device that is at least partially accommodated in the component.

[0066] Such a component surrounding the bearing can therefore fulfill multiple functions simultaneously. In particular, such a component can form a component of an assembly comprising further components that accommodates the bearing, in particular a bearing housing of the vacuum pump.

[0067] According to some embodiments, the transfer element may be disc-shaped, ie the transfer element is flat in that it has an axial height which is smaller than its radial width.

[0068] The axial height of the transfer element may be less than half the axial height of the bearing, in particular less than one third.

[0069] Furthermore, it can be provided that the transfer element comprises a material or consists of a material that is capable of storing the lubricant and / or has a capillary effect.

[0070] In particular, the material can be designed in such a way that it can store and convey the lubricant.

[0071] The material can be, for example, a felt or textile material. The material can be a plastic, in particular a plastic fiber. The plastic can be, for example, polyester, polyimide, polyaramid, or PBO.

[0072] The material for the transfer element can be a sintered material. This material can be a plastic.

[0073] The invention is described below by way of example with reference to the drawings. Fig. 1 a perspective view of a turbomolecular pump known from the prior art, Fig. 2 a view of the underside of the turbomolecular pump of Fig. 1 , Fig. 3 a cross-section of the turbomolecular pump along the Fig. 2shown section line AA, Fig. 4 a cross-sectional view of the turbomolecular pump along the Fig. 2 shown section line BB, Fig. 5 a cross-sectional view of the turbomolecular pump along the Fig. 2 shown section line CC, Fig. 6 the lower part of a turbomolecular vacuum pump containing a bearing housing according to an embodiment of the invention in various views ( Fig. 6a , 6b and 6c ), Fig. 7 an enlarged section of Fig. 6a , Fig. 8in a partial exploded view the bearing socket of Fig. 6 , Fig. 9 an enlarged section of Fig. 8 , Fig. 10 the transfer element of the bearing holder, and Fig. 11 schematically shows part of a bearing holder according to a further embodiment of the invention.

[0074] The Fig. 1The turbomolecular vacuum pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a recipient (not shown) can be connected in a manner known per se. The gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117, to which a backing pump, such as a rotary vane pump, can be connected.

[0075] The inlet flange 113 forms when the vacuum pump is aligned according to Fig. 1 the upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, on which an electronics housing 123 is arranged laterally. Electrical and / or electronic components of the vacuum pump 111 are housed in the electronics housing 123, e.g., for operating an electric motor 125 arranged in the vacuum pump (see also Fig. 3). Several connectors 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, e.g., according to the RS485 standard, and a power supply connector 131 are arranged on the electronics housing 123.

[0076] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0077] On the housing 119 of the turbomolecular pump 111, a flooding inlet 133, in particular in the form of a flooding valve, is provided, via which the vacuum pump 111 can be flooded. In the area of ​​the lower part 121, a sealing gas connection 135, which is also referred to as a purge gas connection, is also arranged, via which purge gas is supplied to protect the electric motor 125 (see e.g. Fig. 3) can be admitted into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111, before the gas delivered by the pump. Furthermore, two coolant connections 139 are arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant, which can be fed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

[0078] The lower side 141 of the vacuum pump can serve as a base, so that the vacuum pump 111 can be operated standing on the underside 141. However, the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a suspended position. Furthermore, the vacuum pump 111 can be designed so that it can also be operated when oriented in a different way than in Fig. 1 As shown. Embodiments of the vacuum pump can also be realized in which the underside 141 is arranged facing sideways or upwards rather than downwards. In principle, any angle is possible.

[0079] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in an upright position.

[0080] On the underside 141, which is Fig. 2As shown, various screws 143 are arranged, by means of which components of the vacuum pump (not further specified here) are fastened together. For example, a bearing cover 145 is attached to the underside 141.

[0081] Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached, for example, to a support surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.

[0082] In the Figures 2 to 5 a coolant line 148 is shown in which the coolant introduced and discharged via the coolant connections 139 can circulate.

[0083] As the sectional views of the Figures 3 to 5 show, the vacuum pump comprises several process gas pumping stages for conveying the process gas present at the pump inlet 115 to the pump outlet 117.

[0084] A rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about a rotation axis 151.

[0085] The turbomolecular pump 111 comprises several turbomolecular pumping stages connected in series for pumping purposes, with several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and secured in the housing 119. A rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular pumping stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

[0086] The vacuum pump also includes Holweck pump stages arranged radially one inside the other and connected in series for pumping efficiency. Other turbomolecular vacuum pumps (not shown) exist that do not have Holweck pump stages.

[0087] The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical-shell-shaped Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the rotation axis 151 and nested within one another in the radial direction. Furthermore, two cylindrical-shell-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the rotation axis 151 and nested within one another in the radial direction.

[0088] The pumping surfaces of the Holweck pump stages are formed by the lateral surfaces, i.e., the radial inner and / or outer surfaces, of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radial inner surface of the outer Holweck stator sleeve 167 lies opposite the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together with the latter forms the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 lies opposite the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with the latter forms a second Holweck pump stage. The radial inner surface of the inner Holweck stator sleeve 169 lies opposite the radial outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175 and together forming the third Holweck pumping stage.

[0089] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. Furthermore, at the upper end of the inner Holweck stator sleeve 169, a radially extending channel can be provided, via which the central Holweck gap 173 is connected to the radially inner Holweck gap 175. This connects the nested Holweck pump stages in series. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0090] The aforementioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves extending spirally around the rotation axis 151 in the axial direction, while the opposing lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and propel the gas in the Holweck grooves to operate the vacuum pump 111. A roller bearing 181 is provided in the area of ​​the pump outlet 117 and a permanent magnet bearing 183 is provided in the area of ​​the pump inlet 115 for rotatably supporting the rotor shaft 153.

[0091] In the area of ​​the rolling bearing 181, a conical spray nut 185 with an outer diameter increasing toward the rolling bearing 181 is provided on the rotor shaft 153. The spray nut 185 is in sliding contact with at least one wiper of a fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), a spray screw can be provided instead of a spray nut. Since different designs are thus possible, the term "spray tip" is also used in this context.

[0092] The operating fluid storage comprises several stacked absorbent discs 187 which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0093] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the operating fluid reservoir via the wiper to the rotating injection nut 185. As a result of centrifugal force, it is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 to the rolling bearing 181, where it fulfills a lubricating function, for example. The rolling bearing 181 and the operating fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

[0094] The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each comprising a ring stack of several permanent magnet rings 195, 197 stacked one on top of the other in the axial direction. The ring magnets 195, 197 are arranged opposite one another, forming a radial bearing gap 199, with the rotor-side ring magnets 195 being arranged radially outward and the stator-side ring magnets 197 being arranged radially inward.

[0095] The magnetic field present in the bearing gap 199 creates magnetic repulsion forces between the ring magnets 195, 197, which effect a radial bearing of the rotor shaft 153. The rotor-side ring magnets 195 are supported by a support section 201 of the rotor shaft 153, which radially surrounds the ring magnets 195 on the outside. The stator-side ring magnets 197 are supported by a stator-side support section 203, which extends through the ring magnets 197 and is suspended from radial struts 205 of the housing 119. The rotor-side ring magnets 195 are fixed parallel to the rotation axis 151 by a cover element 207 coupled to the support section 201. The stator-side ring magnets 197 are fixed parallel to the rotation axis 151 in one direction by a fastening ring 209 connected to the support section 203 and a fastening ring 211 connected to the support section 203.A disc spring 213 may also be provided between the fastening ring 211 and the ring magnets 197.

[0096] Within the magnetic bearing, an emergency or backup bearing 215 is provided, which runs idle without contact during normal operation of the vacuum pump 111 and only engages upon excessive radial deflection of the rotor 149 relative to the stator, forming a radial stop for the rotor 149 to prevent collision of the rotor-side structures with the stator-side structures. The backup bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and / or the stator, causing the backup bearing 215 to be disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 engages is large enough so that the backup bearing 215 does not engage during normal operation of the vacuum pump, and at the same time small enough so that collision of the rotor-side structures with the stator-side structures is prevented under all circumstances.

[0097] The vacuum pump 111 comprises the electric motor 125 for rotating the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, whose rotor shaft 153 extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded in the portion of the rotor shaft 153 extending through the motor stator 217. Between the motor stator 217 and the portion of the rotor 149 extending through the motor stator 217, an intermediate space 219 is arranged, which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

[0098] The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A seal gas, also referred to as purge gas, which can be, for example, air or nitrogen, can enter the motor compartment 137 via the seal gas connection 135. The seal gas can be used to protect the electric motor 125 from process gas, e.g., from corrosive components of the process gas. The motor compartment 137 can also be evacuated via the pump outlet 117, i.e., the vacuum pressure in the motor compartment 137 is at least approximately the vacuum pressure generated by the backing pump connected to the pump outlet 117.

[0099] Furthermore, a so-called labyrinth seal 223, which is known per se, can be provided between the rotor hub 161 and a wall 221 delimiting the motor compartment 137, in particular in order to achieve a better sealing of the motor compartment 217 with respect to the Holweck pump stages located radially outside.

[0100] The Fig. 6 to 10 show an embodiment of a vacuum pump according to the invention, which is designed as a turbomolecular vacuum pump. Fig. 11 relates to a further embodiment of a turbomolecular vacuum pump according to the invention. Apart from the inventive design, these pumps can be designed as described above in connection with the Fig. 1 to 5 Accordingly, a known turbomolecular vacuum pump, as described in the Fig. 1 to 5 shown and described above, can be further developed according to the invention as disclosed here and in particular with reference to the embodiments according to the Fig. 6 to 10 or Fig. 11 shown and described.

[0101] Fig. 6ais a section along the longitudinal axis 11, whereby to the left of the longitudinal axis 11 the section is through a return element 19 and to the right of the longitudinal axis 11 the section is in the area between two return elements 19 which follow one another in the circumferential area. Fig. 6b corresponds Fig. 6a , however, is a perspective view. Fig. 6c shows an enlarged section of Fig. 6b , where a Fig. 6b shown cover element 37 in Fig. 6c is omitted in order to better recognize the interlocking between transfer element 17 and passage section 20 of component 21.

[0102] According to Fig. 6a to 6cIn a lower part 61 of the turbomolecular vacuum pump according to the invention, a bearing mounting assembly is arranged, which includes, among other things, a cup-shaped component 21 with its open side facing downward and closed by a lower axial closure element 63. A lubricant reservoir 43 is partially accommodated in the component 21. For this purpose, a circumferential recess 35 is formed in an upper end face, i.e., on the outside of a bottom section of the cup-shaped component 21, into which the felt ring 17 forming the transfer element is inserted.

[0103] The lubricant reservoir 43 comprises a plurality of stacked discs made of a material that can store and convey a liquid lubricant. An oil, for example, serves as the lubricant. The lubricant reservoir 43 surrounds the lower, conical end of a rotor 13, which rotates about a rotational axis 11 during operation. A bearing 15 in the form of a ball bearing, arranged above the lubricant reservoir 43, serves to rotatably support the rotor 13. The ball bearing 15 comprises an outer ring 15a and an inner ring 15b, between which rolling elements in the form of balls are held. The inner ring 15b adjoins the conical section 13a of the rotor. Fig. 7 shows an enlarged section of Fig. 6c .

[0104] During operation with the rotor 13 rotating, lubricant is transported from the lubricant reservoir 43 to the bearing 15 via the conical section 13a. This lubrication principle is generally known. The lubrication device for the bearing 15, comprising the lubricant reservoir 43 and the conical section 13a, also includes a transfer element 17 surrounding the bearing 15, which is designed as a one-piece felt ring and will be discussed in more detail below, as well as a plurality of return elements 19 arranged circumferentially distributed around the rotational axis 11, each provided in the form of a poroplast rod extending in the axial direction and connected to both the transfer element 17 and the lubricant reservoir 43.

[0105] The concept of a lubricant return system, which comprises an annular transfer element 17 which receives lubricant coming from the bearing 15, as well as return rods 19 extending between the transfer element 17 and the lubricant reservoir 43, is basically known.

[0106] In the embodiment according to the invention according to the Fig. 6 to 10 The aforementioned component 21 comprises a substantially cylindrical passage section 20 that surrounds the bearing 15 in a lower region with a comparatively large radial clearance. Located in the resulting radial space is a damping ring 22, via which the component 21, with its passage section 20, indirectly rests against the outer ring 15a of the bearing 15. As a result, the bearing 15 is radially supported by the component 21.

[0107] In an axially upper region above the damping ring 22, the passage section 20 extends as far as the outer ring 15a of the bearing 15. In this axially upper region, a lubricant passage 25 is formed, which (see also Fig. 7 as well as Figs. 8 and 9 ) comprises a plurality of circumferentially distributed drain holes 16 formed in the outer ring 15a of the bearing 15. These drain holes 16 extend radially relative to the rotational axis 11. The lubricant passage 25 also comprises a circumferential slot 24 formed in the passage section 20, ie, the substantially cylindrical passage section 20, with which the component 21 surrounds the bearing, is cut from the inside in this axially upper region to form the slot 24.

[0108] On the inlet side, the slot 24 is aligned with the outlet openings of the drain holes 16 in the outer ring 15a of the bearing 15. Lubricating oil coming from the bearing 15 thus passes directly into the slot 24 of the lubricant passage 25 formed in the passage section 20 via the radially extending drain holes 16 in the outer ring 15a of the bearing 15. Since the slot 24 lies in the same plane as the drain holes 16, the lubricant passage 25 extends in a single plane perpendicular to the rotation axis 11. This plane intersects the transfer element 17 surrounding the passage section 20. Consequently, the lubricant coming from the bearing 15 passes via the lubricant passage 25 formed by the drain holes 16 and the slot 24 via the shortest path in the radial direction directly to the transfer element 17 in order to be received by the latter and delivered to the rod-shaped return elements 19.

[0109] As in particular the Figs. 8 and 9 As shown, the recess 35 formed in the upper end face of the component 21 and the transfer element 17 formed as an annular disc are complementary to one another. The transfer element 17 comprises a radially outer annular portion 47, from which a plurality of projections 27 distributed in the circumferential direction project radially inward. Accordingly, the passage portion 20 of the component 21 is provided with recesses 29 complementary to the projections 27, into which one of the projections 27 of the transfer element 17 engages when the transfer element 17 is inserted into the recess 35.

[0110] Intermediate sections 31 present between the recesses 29 engage in spaces 33 between the projections 27 of the transfer element 17, wherein the intermediate sections 31 and the spaces 33 are formed complementary to one another.

[0111] The bottom of a respective recess 29 in the passage section 20, located axially at the level of the bottom of the recess 35, is formed by the upper end face of a respective return element 19. When the transfer element 17 is inserted into the recess 35, the return elements 19 are consequently in contact with the projections 27 of the transfer element 17. Lubricant reaching the transfer element 17 and picked up by a respective projection 27 reaches the radially outer annular section 47 of the transfer element 17 due to the capillary action of the material of the transfer element 17, is distributed by this in the circumferential direction and thus to the other projections 27, and is delivered via these to the return elements 19.

[0112] The projections 27 thus serve both to absorb lubricant and to dispense lubricant, wherein the ring section 47 of the transfer element 17 carrying the projections 27 serves to distribute the absorbed lubricant in the circumferential direction.

[0113] This is particularly advantageous when the rotational axis 11 of the rotor 13 is not vertically aligned, i.e., when the vacuum pump is operated with the rotor 13 positioned at an angle in space and, in particular, when the rotor 13 is positioned on its side, i.e., with the rotor 13 running at least substantially horizontally. When the vacuum pump is oriented in this manner, the lubricant does not exit the bearing 15 evenly distributed over the circumference, but rather, due to gravity, primarily through the drain holes 16, which are directed substantially vertically downwards.Despite this circumferentially uneven delivery of the lubricant to the individual projections 27 of the transfer element 17, all return elements 19 can contribute to the return of the lubricant to the lubricant reservoir 43, since the lubricant primarily absorbed by only some projections 27 is distributed via the annular section 47 of the transfer element 17 to the other projections 27 and is thus delivered to all return elements 19.

[0114] By engaging the transfer element 17 into the passage section 20 by means of its inwardly projecting projections 27, the transfer element 17 extends comparatively close to the bearing 15 without adversely mechanically weakening the passage section 20 and thus the component 21. At the same time, particularly effective lubricant absorption is ensured, particularly due to the projections 27 tapering toward their free ends.

[0115] The permeability of the passage section 20 for the lubricant is realized in a particularly simple manner in terms of manufacturing technology by the slot 24 formed on the inside. During the manufacture of the component 21, it is therefore only necessary to cut the passage section 20 from the inside at the relevant axial height, wherein the radial depth of the slot 24 is selected such that the slot 24 opens into the recesses 29 and thus forms a lubricant outlet 23 there (cf. in particular Fig. 9 ), but ends in the intermediate sections 31 located between the recesses 29 in the radial direction in front of the recess 35.

[0116] Lubricant escaping through the drain holes 16 in the outer ring 15a of the bearing 15 can thus only reach the recesses 29 and thus exclusively the projections 27 of the transfer element 17 engaging there.

[0117] Axially extending passages 41 are formed in the component 21 for the rod-shaped return elements 19. The return elements 19 can each extend through these passages 41 from the underside of one of the projections 27 of the transfer element 17 to the lubricant reservoir 43.

[0118] The component 21 is also provided with a collar section 39, with which the component 21 engages over the bearing 15 at the end face. The collar section 39 initially extends from the passage section 20 in an axial upward direction and then radially inward. At its free end, the collar section 39 is provided with a comparatively narrow, axially downwardly projecting circumferential web section 40. As can be seen in particular from the enlarged illustration of the Fig. 7shows, the collar section 39 has the shape of a U open towards the bearing 15 with U-legs of different lengths and widths in a sectional plane running parallel to the axis of rotation 11.

[0119] The collar portion 39 protrudes upward in the axial direction from a lid-shaped cover element 37, which is provided with a central opening 38 for this purpose. A cover portion 37a of the cover element 37, which extends perpendicular to the axis of rotation 11 and in which the aforementioned central opening 38 is formed, has a smaller axial height than the transfer element 17 and is thus comparatively thin, thereby saving axial height. Furthermore, the cover element 37 comprises a circumferential wall portion 37b extending in the axial direction, via which the cover element 37 is pressed onto the component 21.

[0120] The cover element 37 thus forms an upper axial closure element of the bearing housing assembly, which, due to the small axial height of the cover section 37a, contributes only insignificantly to the axial height of this assembly.

[0121] In this embodiment, both aspects of the invention are realized, ie the transfer element 17 surrounds the bearing 15 and engages in the passage section 20.

[0122] In a modified embodiment of this exemplary embodiment, the transfer element 17 can also be arranged axially higher, with the basic structure of the bearing support assembly otherwise remaining the same, if this is necessary due to specific circumstances. For example, the axial position of the transfer element 17 can be selected such that its axial underside lies at least approximately in the same plane as the axial top side of the bearing 15 or at a comparatively small axial distance, which is in particular smaller than the axial height of the transfer element 17, above the plane defined by the axial top side of the bearing 15. To ensure that the lubricant can also reach the transfer element 17 from the bearing 15 to the transfer element 17 in this arrangement, the course of the lubricant passage 25 is then adapted accordingly.The drainage holes 16 in the outer ring 15a of the bearing 15 can each be provided as holes running obliquely to the axis of rotation 11, which are aligned with a conical slot 24 in the passage section 20, i.e. the lubricant passage 25 formed jointly by the drainage holes 16 and the slot 24 then lies in a conical surface having the axis of rotation 11 as its central axis. Furthermore, the transfer element 17 and the passage section 20 adapted to its higher axial position are then interlocked, wherein the projections 27 of the transfer element 17 and the recesses 29 of the passage section 20 can extend obliquely to the axis of rotation 11. If the transfer element 17 is made of a deformable material such as felt, the projections 27 can, for example, simply be bent downwards relative to the ring section 47 during assembly and pressed into the recesses 29.

[0123] In this modified embodiment, the second aspect of the invention is thus realized, but not its first aspect, ie the transfer element 17 does not surround the bearing 15, but engages in the passage section 20.

[0124] Fig. 11 shows a further embodiment of a partially illustrated bearing support assembly of a turbomolecular vacuum pump according to the invention.

[0125] In this exemplary embodiment, the transfer element 17, again designed as an annular disc made of felt or another suitable material, directly surrounds the outer ring 15a of the ball bearing 15. The outer ring 15a of the bearing 15 in turn comprises a plurality of drainage bores 16 distributed in the circumferential direction and extending radially relative to the rotational axis 11, which together form a lubricant passage 25 through which lubricant coming from the bearing 15 reaches the transfer element 17.

[0126] In this embodiment, the transfer element 17 extends up to the bearing 15, ie no further component is arranged between the bearing 15 and the transfer element 17.

[0127] An upper axial end of the bearing housing assembly is formed here by an annular upper component 51, while an axially lower end is formed by a lower component 55. A peripheral component 53 surrounds the bearing 15 at a radial distance, with a damping ring 22 arranged in the resulting intermediate space.

[0128] Passages 51 are formed in the peripheral component 53, in each of which a rod-shaped return element 19 is arranged, via which lubricant received by the transfer element 17 can be returned to a lubricant reservoir (not shown here). The return elements 19 also each extend through the lower component 55. List of reference symbols

[0129] 11Rotation axis 13Rotor 13aCone section 15Bearing 15aOuter ring 15bInner ring 16Drain hole 17Transfer element 19Return element 20Passage section 21Component 22Damping ring 23Lubricant outlet 24Slot 25Lubricant passage 27Protrusion 29Recess 31Intermediate section 33Gap 35Depression 37Cover element 37aCover section 37bWall section 38Opening 39Collar section 40Web section 41Passage 43Lubricant reservoir 45Bearing holder 47Ring section 51Upper component 53Peripheral component 55Lower component 61Lower part 63End element

Claims

1. Vacuum pump, in particular a turbomolecular vacuum pump, with - at least one pumping stage which comprises a stator and a rotor (13) which rotates about an axis of rotation (11) relative to the stator during operation, - a bearing (15), in particular a rolling bearing, for the rotor (13), and - a lubricating device for lubricating the bearing (15) with a liquid lubricant, wherein the lubricating device comprises an annular or partially annular transfer element (17) which runs around the axis of rotation (11), which receives lubricant coming from the bearing (15) and delivers it to a return device (19) of the lubricating device, wherein the transfer element (17) surrounds the bearing (15) and / or wherein the transfer element (17) engages radially or with a radial component in a passage section (20) surrounding the bearing (15), through which passage section lubricant can pass from the bearing (15) to the transfer element (17).

2. Vacuum pump according to claim 1, wherein the transfer element (17) on the one hand and a lubricant outlet (23) of a lubricant passage (25) for the lubricant leading to the transfer element (17) and extending radially or with a radial component on the other hand are axially aligned with one another.

3. Vacuum pump according to claim 2, wherein the lubricant passage (25) is formed in the bearing (15) and / or extends through a passage section (20) surrounding the bearing (15).

4. Vacuum pump according to claim 2 or 3, wherein the lubricant passage (25) is formed circumferentially around the axis of rotation (11) or comprises a plurality of discrete individual passages distributed around the axis of rotation (11).

5. Vacuum pump according to one of the preceding claims, wherein the transfer element (17) has a plurality of projections (27) distributed in the circumferential direction, projecting radially or with a radial component inwards, in particular tapering towards their free end.

6. Vacuum pump according to claim 5, wherein recesses (29) for the projections (27) are formed in the passage section (20), into which recesses the transfer element (17) engages with its projections (27), ***in particular wherein intermediate sections (31) of the passage section (20) located between the recesses (29) engage in spaces (33) of the transfer element (17) present between the projections (27).

7. Vacuum pump according to claim 5 or 6, wherein the projections (27) and the recesses (29) are formed at least substantially complementary to one another.

8. Vacuum pump according to claim 6 or 7, wherein a lubricant passage (25) formed in the passage section (20) opens exclusively into the recesses (29).

9. Vacuum pump according to one of the preceding claims, wherein the return device comprises a plurality of return elements (19) arranged distributed in the circumferential direction, in particular extending axially or with an axial component, which are in contact with the transfer element (17) at discrete points distributed around the axis of rotation (11).

10. Vacuum pump according to one of the preceding claims, wherein the transfer element (17), in particular completely, is received in a front-side recess (35) of a component (21) surrounding the bearing (15), in particular comprising the passage section (20), in particular wherein the transfer element (17) and the recess (35) are designed to be at least substantially complementary to one another.

11. Vacuum pump according to one of the preceding claims, wherein a component (21) surrounding the bearing (15), in particular comprising the passage section (20), is covered on the end face by a separate cover element (37).

12. Vacuum pump according to one of the preceding claims, wherein a component (21) surrounding the bearing (15), in particular comprising the passage section (20), and receiving the transfer element (17) is formed in one piece.

13. Vacuum pump according to one of the preceding claims, wherein a component (21) surrounding the bearing (15), in particular comprising the passage section (20), engages over the bearing (15) with a collar section (39) on the end face.

14. Vacuum pump according to one of the preceding claims, wherein a component (21) surrounding the bearing (15), in particular comprising the passage section (20), is at least approximately cup-shaped, in particular wherein a recess (35) receiving the transfer element (17) is formed on the outer side of a base section of the component (21), which recess surrounds a collar section (39) of the component (21) which engages over the bearing (15) at the end face and from which a plurality of passages (41) distributed in the circumferential direction extend, through which return elements (19) of the return device extend from the transfer element (17) to a lubricant reservoir (43) of the lubricating device which is at least partially accommodated in the component (21).

15. Vacuum pump according to one of the preceding claims, wherein the transfer element (17) is disc-shaped and / or wherein the transfer element (17) comprises or consists of a material which is capable of storing the lubricant and / or has a capillary action.

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