Vacuum device and vacuum system

Abstract

The invention relates, inter alia, to a vacuum device, in particular a turbomolecular pump, comprising a passage, namely an inlet or an outlet; and a flange for a vacuum-tight connection of the passage of the vacuum device with another vacuum device in a connection direction along a connection axis; wherein the flange has a sealing area extending circumferentially around the connection axis for the attachment of a sealing element; wherein the vacuum device has an end radially axial with respect to the connection axis within the sealing area in the connection direction;and wherein the sealing area of ​​the flange is axially recessed relative to the axial end of the vacuum device in the opposite direction of connection, or wherein the sealing area of ​​the flange is arranged in the same axial position as the axial end of the vacuum device, or wherein the sealing area of ​​the flange projects axially in the direction of connection by a maximum of 2 mm, 3 mm, or 4 mm relative to the axial end of the vacuum device.

Description

[0001] The invention relates to a system comprising a vacuum device, namely a vacuum pump, in particular a turbomolecular pump, and a sealing element, according to the preamble of claim 1.

[0002] A hybrid-bearing turbomolecular pump, considered here as an example of vacuum devices of the aforementioned types, has two different bearing principles at the two rotor ends: On the forevacuum side, where higher pressures prevail, an oiled or grease-lubricated ball bearing is used. On the high-vacuum side, however, where all hydrocarbons must be avoided, a permanent magnet bearing is employed. A stator portion of this permanent magnet bearing must be connected to the pump housing in some way to fulfill its function. In the vast majority of designs, the stator portion is connected to the pump housing by the so-called star, i.e., a support in the inlet. Standardized flange connections are preferred for connecting the high-vacuum flange of the turbopump to a vacuum chamber. In some designs, an O-ring is placed between the two flanges for sealing.For easier handling and support of the O-ring, it is usually positioned radially between two aluminum rings, one of which also serves as a centering ring. This combination of O-ring and aluminum rings is commonly referred to as a "centering ring" in vacuum engineering terminology. Additionally, grid-like inserts, such as a protective grid and / or splinter guard, may be placed inside the two aluminum rings to prevent objects from falling into the turbopump. These are located above the star-shaped centering ring. The centering ring, possibly with a protective grid or splinter guard, is a readily available component and, due to the standardization of flanges, can be supplied by various vacuum component manufacturers.

[0003] US 2015 / 0060691 A1 describes a turbomolecular vacuum pump in which the flange is recessed so that the pump inlet can protrude through the wall of a vacuum chamber and into the interior of the vacuum chamber. A sealing element in the form of a centering ring for contact with the flange is not described.

[0004] From DE 10 2009 039 120 A1 a turbomolecular vacuum pump with a recessed flange is also known, but a sealing element in the form of a centering ring for contact with the flange is not described.

[0005] In this context, reference is also made to US 2008 / 0226387 A1, which describes, among other things, that a groove for an O-ring is formed in a flange of a turbomolecular vacuum pump.

[0006] US 2018 / 0274556 A1 describes a turbomolecular vacuum pump with a centering ring, wherein the flange of the turbomolecular vacuum pump is not recessed.

[0007] One objective of the invention is to improve a flange connection between two vacuum devices.

[0008] This problem is solved by a system with the features of claim 1, namely a system with a vacuum pump, in particular a turbomolecular pump, and a sealing element, wherein the vacuum pump comprises the features of the vacuum device according to the first aspect disclosed below, namely according to the first alternative, in which the sealing area of ​​the flange is axially recessed with respect to the axial end of the vacuum device opposite the connection direction. The sealing element is formed by a centering ring, wherein the centering ring comprises a deformable sealing element, preferably an O-ring, and at least one at least substantially rigid holder for the sealing element.

[0009] The vacuum pump of the system according to the invention can be further developed according to the further developments of the vacuum device disclosed below, provided that these are not further developments which require the features of the second alternative or the third alternative.

[0010] A first, non-inventive aspect of the present disclosure relates to a vacuum device comprising a passage, namely an inlet or an outlet, and a flange for a vacuum-tight connection of the passage of the vacuum device with another vacuum device in a connection direction along a connection axis, wherein the flange has a sealing area extending circumferentially around the connection axis for the attachment of a sealing element, and wherein the vacuum device has an end radially axial with respect to the connection axis within the sealing area in the connection direction.It is provided that the sealing area of ​​the flange is axially offset backwards from the axial end of the vacuum device in the opposite direction of the connection (first alternative), or that the sealing area of ​​the flange is arranged in the same axial position as the axial end of the vacuum device (second alternative), or that the sealing area of ​​the flange projects axially in the direction of the connection by a maximum of 2 mm, in particular a maximum of 1.5 mm, in particular a maximum of 1 mm, or by a maximum of 3 mm or by a maximum of 4 mm (third alternative).

[0011] This reduces the axial length of the vacuum device. At the same time, commercially available and standardized components, especially centering rings, can still be used for connection to the flange.

[0012] Fastening elements and / or a standard-compliant additional flange. The axial length of the vacuum device is reduced even if the sealing area protrudes. With respect to a specific standardized sealing element, particularly a standardized centering ring with specific axial dimensions, the sealing area needs to protrude less far from the axial end of the vacuum device due to this concept than without it.

[0013] A standardized flange connection has a largely fixed axial length. According to the first aspect, the sealing area is axially offset from the axial end of the vacuum device, or the sealing area of ​​the flange is located in the same axial position as the axial end of the vacuum device, or the sealing area of ​​the flange projects axially in the connection direction by a maximum of 2 mm, 3 mm, or 4 mm relative to the axial end of the vacuum device. This shifts the flange connection axially away from the opening and towards an axial center of the vacuum device, specifically along the outside of the housing. The axial length required for the flange connection is thus at least partially covered on the outside of the housing, where it does not contribute to an axial extension of the vacuum device. In other words, the axial end of the vacuum device is shifted towards or into the flange connection.A support and the other components of the vacuum device can thus be arranged axially closer to the rest of the vacuum device, resulting in a saving of axial installation space without sacrificing compatibility with the available standard flanges and accessories, i.e. sealing elements and fastening elements.

[0014] The vacuum device is a vacuum pump, specifically a turbomolecular pump.

[0015] The passage can, in particular, be an inlet of the vacuum device.

[0016] The axial end of the vacuum device is defined, for example, by a component arranged in the passage. This can be, for example, a carrier for a functional element of the vacuum device. The functional element held by the carrier can be, for example, a component of a bearing element, in particular a magnetic bearing, especially a stator part and / or inner ring.

[0017] The axial end of the vacuum device can also be defined by a component that defines the passage. This could be, for example, the housing of the vacuum device and / or a section formed integrally with the flange.

[0018] It is also possible that the axial end of a component arranged in the passage and the axial end of a component defining the passage coincide axially, so that both form the axial end of the vacuum device.

[0019] Generally, the term component does not necessarily refer to a part separate from other components. For example, the opening can be defined by the housing, which also includes a flange integrally connected to it. Similarly, a component located within the opening can be either separate from or integrally connected to the component defining the opening, particularly the housing. For instance, a component, especially a support for a functional element, can be located within the opening and integrally connected to the housing, or it can be designed separately from it.

[0020] According to one embodiment, a component arranged in the passage, such as a support, can be fixed to an inside of the component defining the passage, in particular the housing, and can be held axially, for example, by a shoulder of the component.

[0021] According to this first aspect, the sealing area is set back from the axial end of the vacuum device, arranged in the same axial position, or projects forward by a maximum of 2 mm, 3 mm, or 4 mm, with the axial end of the vacuum device being defined radially within the sealing area. The vacuum device can therefore, in principle, be designed arbitrarily radially beyond the sealing area or the flange connection and, for example, project axially beyond it. However, it is precisely the displacement of the radially inner axial end towards or into the flange connection, or the setback of the flange connection relative to this axial end, that results in the advantageous saving of axial installation space. Therefore, whenever reference is made to an axial end in the following, this refers to the end radially within the sealing area, unless otherwise specified.

[0022] The sealing area is designed in particular as a flat annular surface, which runs perpendicular to the connection axis and / or connection direction. In principle, the sealing area can be radially limited, for example, by a centering shoulder, especially for a centering area of ​​a sealing element designed as a centering ring.

[0023] The connection direction describes the direction that runs from the vacuum device to the further vacuum device to be connected along the connection axis. The sealing area is set back in the opposite direction to the connection direction, and is therefore preferably arranged axially behind the axial end of the vacuum device being claimed from the perspective of the further vacuum device.

[0024] According to a further development, the axial distance between the axial end of the vacuum device and a recessed sealing area can be at least 5 mm, in particular at least 10 mm, and in particular at least 15 mm. This results in a particularly far axial recess for the flange connection, and the corresponding saving in axial installation space is substantial.

[0025] According to an alternative variant with less space saving but better compatibility, the axial distance between the end of the vacuum device and a recessed sealing area is provided to be at most 3 mm, in particular at most 2 mm.

[0026] For the purposes of this disclosure, a sealing element for the flange connection is not considered part of the vacuum device for the purposes of unambiguous reference, particularly since such sealing elements are frequently sold independently of vacuum devices. After all, they are usually standardized components.

[0027] Nevertheless, the present disclosure includes embodiments that relate to the sealing element, which is why, in general, a system comprising a vacuum device according to one of the variants described above and a sealing element in or for attachment to the sealing area of ​​the vacuum device is also disclosed. Insofar as reference is made below to a sealing element, this generally refers to an embodiment of the system.

[0028] Particularly within the system, the sealing area of ​​the flange can project axially by more than 2 mm in the connection direction with respect to the axial end of the vacuum device; that is, such configurations are also the subject of the present disclosure, but not according to the invention. The sealing element has an axial end directed opposite to the connection direction, which is in the same axial position as the axial end of the vacuum device or is axially offset from it. This advantageously achieves a gain in installation space, especially with larger sealing elements.

[0029] According to one embodiment, a protective element, in particular a grid element, is connected to the sealing element and spans the inlet. The sealing area can generally be arranged axially such that a sealing element, to which a protective element spanning the inlet is connected, can be positioned against the sealing area. This ensures that standard components with protective elements can also be used, so that the pump can be reliably protected against the ingress of foreign objects. Nevertheless, a relatively small axial gain in installation space is achieved compared to other embodiments. In principle, even a reduction of just a few millimeters in installation space can lead to significantly improved handling of the vacuum device. The protective element can be, for example, a grid element, a protective grille, and / or a splinter guard.

[0030] In principle, a protective element can be provided on the vacuum device itself, so that the axial offset of the sealing area can be greater and more installation space is saved because it is not necessary for a protective element to be arranged on the sealing element.

[0031] In another embodiment, the sealing element has an axial thickness when installed in the flange connection, wherein the axial distance between the axial end of the vacuum device and the sealing area is at most half the thickness of the sealing element. This also improves compatibility with standard components.

[0032] The sealing element of the system according to the invention is formed by a centering ring. In principle, the sealing element can comprise, for example, an elastomer seal and / or an O-ring.

[0033] The axial end of the vacuum device is defined not only radially within the sealing area, but also radially within the sealing element.

[0034] The flange is preferably arranged on a housing of the vacuum device, in particular integrally connected to it, for example by welding or by being manufactured from a single blank. The housing defines, in particular, the passage.

[0035] An axial end of the vacuum device housing can preferably correspond in its axial position to that of a component arranged in the passage or be axially offset relative to it in the opposite direction of connection. In particular, the axial housing end can be arranged in the axial direction between the axial end of the component arranged in the passage and the sealing area.

[0036] A second aspect of the present disclosure, which is not part of the invention, relates to a vacuum device, in particular a turbomolecular pump, with a flange for a vacuum-tight connection of the vacuum device to a further flange of a further vacuum device, wherein the flange has several fastening points arranged distributed over a circumference of the flange, in particular with through-holes for fastening elements to be assigned to each, at which the flange can be fastened to the further flange, wherein a sealing area circumferential with respect to a connecting axis is provided on the flange for bearing a sealing element to be arranged between the flanges, wherein the sealing area is arranged radially within the fastening points with respect to the connecting axis, and wherein an axial projection is provided on the flange radially outside the sealing area with respect to the connecting axis, which forms a bearing surface for the further flange.

[0037] The projection and contact surface provide support for the flange connection. This reduces deformation of the flanges and connected components, particularly a support for a functional element, as described above, due to force application during connection manufacturing. This results in more manageable tolerances in the connection area, which can improve both the vacuum tightness of the flange connection and the service life of functional elements. The support is generally provided in addition to and separately from the sealing element, especially the centering ring, so that it prevents tilting deformation of at least one flange at the sealing element.

[0038] In an exemplary vacuum device, particularly a turbomolecular pump, a flange connection of type ISO-F, especially according to ISO 1609 or DIN 28404, is provided, wherein the flange is to be attached to another flange by means of a centering ring. The other flange can also generally be referred to as a mating flange. When tightening fasteners, such as mounting screws, deformation of the flange and mating flange can occur. The centering ring acts as the pivot point of the lever. This can lead to a displacement of a functional element, such as a permanent magnet bearing, via a support or star joint. Due to the no longer optimal positioning of the rotor bearing points, this can lead to increased wear of a ball bearing and increased noise emission from the pump.

[0039] The underlying approach reduces, and in particular prevents, flange deformation. In the turbomolecular pump described in the preceding paragraph, this ensures a more precise fit of the pump rotor in its bearings. To achieve this, the flange and mating flange are supported against each other outside of fastening points or force application points, particularly outside the sealing area and / or the seat of a centering ring, by the contact surface of the projection. This support is preferably provided by at least the axial thickness of the centering ring, but more specifically by less than the unloaded thickness of an O-ring located within the centering ring. The flange is thus effectively extended by the projection towards the mating flange. In particular, the non-deformable elements of the centering ring are positioned in a recessed area at the opening defined by the flange, especially the inlet.The recess can, for example, be created simply by turning.

[0040] The approach therefore stipulates, in particular, that the flange's contact surface rests directly against the mating flange or at least against a component supporting the mating flange. This reduces, and in particular prevents, deformation of the flanges and connected components, especially independently of any force exerted by at least one fastening element, particularly the tightening torque of fastening bolts. The contact surface acts as a counter-bearing for the lever between the fastening point and the sealing element, especially a centering ring. An O-ring, preferably located within the centering ring, is thicker than the axial height of the contact surface with respect to the sealing area or projection. This ensures a reliable seal.

[0041] According to one embodiment, the contact surface and / or projection is provided radially outside the fastening points, not necessarily, but optionally exclusively there. This further improves the support of the counter flange. In particular, this provides especially reliable support for a lever between the fastening element and the sealing element.

[0042] The projection can, for example, extend around the connecting axis or be formed by several projections, particularly those distributed around the circumference. In principle, the projection can, for example, be designed as a web.

[0043] In principle, a protrusion or contact surface can be located not only radially outside the sealing area or the mounting points. For example, a contact surface and / or protrusion can also be provided radially within the mounting points, or the contact surface and / or protrusion can extend from radially outside the mounting points to radially inside them.

[0044] Furthermore, the contact surface and / or projection can be located radially within the area of ​​a fastener, particularly a screw shank, and / or radially outside and / or inside it. Fastening points are generally defined as those points where the axis of a respective fastener intersects the connecting plane, which runs perpendicular to the connecting axis. The axial position of the point or plane is of secondary importance. For simplicity, one can also speak of radially outside or inside the axes of the fasteners. The axis and / or a screw shank can therefore be radially free from the projection or contact surface, or not. For example, the fastening points or axes can be defined by through-holes in the flange and / or associated fasteners.

[0045] In principle, it is advantageous if the contact surface extends to a radial outer edge of the flange, in particular if it is arranged only on the radial outer edge and / or is radially spaced from the sealing area and / or fastening point or element, in particular a fastening axis thereof or a screw shank.

[0046] The contact surface and / or projection can be integrally connected to the flange or formed by a separate component. For example, the projection or web can be designed as a separate ring. This separate component can be easily removed by the customer, for instance, if they wish to forgo a centering ring because the mating flange has a groove for a sealing element.

[0047] For example, the contact surface can be arranged to project axially with respect to the sealing area, particularly in a connection direction. Advantageously, the contact surface is positioned axially between the sealing area and a vacuum device to be connected.

[0048] In a further development, the axial distance between the system and the sealing area is at least 3.7 mm and at most 4.1 mm, in particular 3.9 mm, or at least 5.4 mm and at most 5.8 mm, in particular 5.6 mm. This results in particularly good support and particularly low flange deformation while simultaneously ensuring good sealing performance.

[0049] According to a further development, the projection can be designed to be essentially circumferential with respect to the connection axis, with an opening in the projection or a groove in the contact surface extending from a radially inner end of the projection or contact surface to a radially outer end of the projection or contact surface. This significantly simplifies leak detection. If the flange and mating flange are in direct contact around their circumference, the leak detection gas can no longer easily reach the sealing area and the sealing element. The opening or groove provides easy access for the leak detection gas to the sealing area.

[0050] Regarding the second aspect, a system comprising a vacuum device according to at least one of the variants described above and a sealing element in or for contact with the sealing area of ​​the vacuum device is disclosed. One embodiment provides that an axial distance between the contact surface and the sealing area corresponds to an axial thickness or height of the sealing element when installed in the flange connection. This results in particularly low deformation of the flange and connected components. In general, the axial distance can correspond to an axial height of a fixed part of a sealing element, particularly one designed as a centering ring. Fundamentally, the axial distance can also correspond, for example, to the axial height of a metal gasket.

[0051] The flange can, for example, be connected to a housing of the vacuum device, preferably being formed integrally with the housing. In this case, the advantages of the present disclosure are particularly pronounced.

[0052] Preferably, the flange can be an inlet flange of the vacuum device, specifically a vacuum pump. Here, the improved vacuum tightness due to the lower pressures compared to the outlet is particularly advantageous.

[0053] The sealing element of the system according to the invention is formed by a centering ring. , wherein the centering ring comprises a deformable sealing element, preferably an O-ring, and a holder for the sealing element that is at least substantially rigid. For example, the sealing element can be a standard component.

[0054] The advantages of the present disclosure are particularly evident when the vacuum device is designed as a turbomolecular pump with a bearing element, in particular a magnetic bearing, wherein a support for a component of the bearing element is connected to the flange and / or to a housing of the turbomolecular pump. The reduction in flange deformation has a particularly positive effect on the service life of the pump, since the rotor positioning can be maintained with a high degree of accuracy.

[0055] The system may further comprise another vacuum device to be connected or already connected, with a further flange or counter flange. The system may further comprise at least one fastening element for attaching the flange of the vacuum device to the further flange of the further vacuum device, in particular a set of fastening elements. The sealing element may, in particular, be designed to be arranged between respective opposing sealing areas of the flanges, especially in a compressed manner, or be arranged in such a way.

[0056] The invention is described below by way of example with reference to advantageous embodiments and the accompanying figures. These show, schematically: Fig. 1 a perspective view of a turbomolecular pump, 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 in Fig. 2Section line AA shown, Fig. 4 a cross-sectional view of the turbomolecular pump along the in Fig. 2 Section line BB, Fig. 5 shows a cross-sectional view of the turbomolecular pump along the line shown in Fig. 2 Section line CC shown, Figs. 6 to 9 each show a turbomolecular pump with an inlet flange in a sectional partial view , where only the Figs. 7 to 9 According to the invention, Figs. 10 to 14 each show a turbomolecular pump with an inlet flange to illustrate an aspect not according to the invention.

[0057] The in Fig. 1The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a receiver (not shown) can be connected in a manner known per se. The gas from the receiver can be drawn out of the receiver 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.

[0058] The inlet flange 113 forms a Fig. 1The upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, to which an electronics housing 123 is attached laterally. The electronics housing 123 contains electrical and / or electronic components of the vacuum pump 111, e.g., for operating an electric motor 125 located in the vacuum pump. The electronics housing 123 has several connections 127 for accessories. In addition, a data interface 129, e.g., according to the RS485 standard, and a power supply connection 131 are located on the electronics housing 123.

[0059] The housing 119 of the turbomolecular pump 111 has a flood inlet 133, in particular in the form of a flood valve, through which the vacuum pump 111 can be flooded. In the area of ​​the lower part 121, a purge gas connection 135, also referred to as a purge gas connection, is also arranged, through which purge gas can be supplied to protect the electric motor 125 (see e.g. Fig. 3) before the gas pumped by the pump can be brought into the engine compartment 137, in which the electric motor 125 is housed in the vacuum pump 111. In the lower part 121, two coolant connections 139 are also arranged, one of the coolant connections being provided as an inlet and the other as an outlet for coolant that can be directed into the vacuum pump for cooling purposes.

[0060] The lower side 141 of the vacuum pump can serve as a base, allowing the vacuum pump 111 to be operated standing upright on its underside 141. Alternatively, the vacuum pump 111 can be attached to a receiver via the inlet flange 113 and thus operated in a suspended position. Furthermore, the vacuum pump 111 can be designed to operate even when oriented differently than described. Fig. 1as shown. It is also possible to realize embodiments of the vacuum pump in which the underside 141 can be arranged facing not downwards, but to the side or upwards.

[0061] On the underside 141, which is in Fig. 2 As shown, various screws 143 are arranged, by means of which components of the vacuum pump, not further specified here, are fastened to one another. For example, a bearing cover 145 is attached to the underside 141.

[0062] On the underside 141, there are also mounting holes 147, via which the pump 111 can be attached to a support surface, for example.

[0063] In the Figures 2 to 5 A coolant line 148 is shown, in which the coolant introduced and removed via the coolant connections 139 can circulate.

[0064] Like the sectional views of the Figures 3 to 5As shown, 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.

[0065] A rotor 149 is arranged in the housing 119, which has a rotor shaft 153 rotatable about a rotation axis 151.

[0066] The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series to provide pumping action. These stages have several radial rotor disks 155 attached to the rotor shaft 153 and stator disks 157 arranged between the rotor disks 155 and fixed in the housing 119. Each rotor disk 155 and an adjacent stator disk 157 form a turbomolecular pump stage. The stator disks 157 are held at a desired axial distance from each other by spacer rings 159.

[0067] The vacuum pump also comprises Holweck pump stages arranged radially one inside the other and connected in series for pumping effect. The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical Holweck rotor sleeves 163, 165 attached to and supported by the rotor hub 161, which are oriented coaxially to the axis of rotation 151 and nested one inside the other in the radial direction. Furthermore, two cylindrical Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and nested one inside the other in the radial direction.

[0068] The pump-active surfaces of the Holweck pump stages are formed by the outer 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 faces the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together they form the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together they form 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 they form the third Holweck pumping stage.

[0069] At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, through which the radially outer Holweck slot 171 is connected to the central Holweck slot 173. Furthermore, a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, through which the central Holweck slot 173 is connected to the radially inner Holweck slot 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.

[0070] The aforementioned pump-active surfaces of the Holweck stator sleeves 163, 165 each have several Holweck grooves spiraling around the axis of rotation 151 in the axial direction, while the opposite outer surfaces of the Holweck rotor sleeves 163, 165 are smooth and drive the gas forward in the Holweck grooves for the operation of the vacuum pump 111.

[0071] For the rotatable mounting of the rotor shaft 153, a rolling 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.

[0072] In the area of ​​the rolling bearing 181, a conical injection nut 185 with an outer diameter increasing towards the rolling bearing 181 is provided on the rotor shaft 153. The injection nut 185 is in sliding contact with at least one wiper of a lubricant reservoir. The lubricant reservoir comprises several stacked absorbent discs 187, which are impregnated with a lubricant for the rolling bearing 181, e.g., a lubricant.

[0073] During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the fluid reservoir via the wiper to the rotating injection nut 185 and, as a result of centrifugal force, is conveyed along the injection nut 185 in the direction of the increasing outer diameter of the injection nut 185 towards the rolling bearing 181, where it performs, for example, a lubricating function. The rolling bearing 181 and the fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

[0074] The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each containing a ring stack of several axially stacked permanent magnet rings 195, 197. The ring magnets 195, 197 face each other, forming a radial bearing gap 199, with the rotor-side ring magnets 195 arranged radially outside and the stator-side ring magnets 197 radially inside. The magnetic field present in the bearing gap 199 induces magnetic repulsion forces between the ring magnets 195, 197, which result in the radial support 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. Parallel to the axis of rotation 151, the rotor-side ring magnets 195 are fixed by a cover element 207 coupled to the support section 203. The stator-side ring magnets 197 are fixed in one direction parallel to the axis of rotation 151 by a retaining ring 209 connected to the support section 203 and a retaining ring 211 also connected to the support section 203. A disc spring 213 may also be provided between the retaining ring 211 and the ring magnets 197.

[0075] Within the magnetic bearing, an emergency or catch bearing 215 is provided, which runs freely without contact during normal operation of the vacuum pump 111 and only engages when there is excessive radial deflection of the rotor 149 relative to the stator, in order to form a radial stop for the rotor 149, thus preventing a collision between the rotor-side and stator-side structures. The catch bearing 215 is designed as an unlubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator, which causes the catch bearing 215 to be disengaged during normal pump operation. The radial deflection at which the catch bearing 215 engages is dimensioned to be large enough so that the catch bearing 215 does not engage during normal operation of the vacuum pump, and simultaneously small enough to prevent a collision between the rotor-side and stator-side structures under all circumstances.

[0076] 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 section of the rotor shaft 153 extending through the motor stator 217. A space 219 is arranged between the motor stator 217 and the section of the rotor 149 extending through the motor stator 217. This space comprises a radial motor gap through which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

[0077] The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A purge gas, also known as a sealing gas, which can be, for example, air or nitrogen, can enter the motor compartment 137 via the purge gas connection 135. This purge gas protects 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, meaning that the vacuum pressure in the motor compartment 137 is at least approximately equal to that produced by the backing pump connected to the pump outlet 117.

[0078] Between the rotor hub 161 and a wall 221 bounding the engine compartment 137, a so-called labyrinth seal 223, which is known per se, can also be provided, in particular to achieve a better seal of the engine compartment 217 against the radially outside Holweck pump stages.

[0079] In the Fig. 6 A prior art turbomolecular pump is shown in a sectional view. A partial view is shown, revealing an inlet flange 20. The flange 20 is part of a housing 22 and serves to connect to another vacuum device (not shown), for example, a vacuum chamber.

[0080] In this example, flange 20 is designed as an ISO-K flange. It is connected to another flange of the vacuum device to be connected (not shown) via separate fastening elements (also not shown), which grip the flanges like a clamp. Each fastening element engages behind a circumferential projection 24 of flange 20.

[0081] A centering ring 26 rests against the flange 20. This ring comprises an O-ring 28, which is radially enclosed between two fixed, in particular metallic, ring elements 30. The centering ring 26 thus forms a sealing element for the flange connection. The centering ring 26 also includes a protective element designed as a grid element 32, which spans an inlet 34 defined by the flange 20, so that the interior of the pump is protected from foreign objects.

[0082] In the inlet 34 is a support 36, which carries a functional element 38, in this case a static part of a bearing and specifically a set of internal permanent magnets of a magnetic bearing. The support 36 is supported on the housing 22, specifically on its inner side. Axially, the support 36 is fixed to a shoulder of the housing 22 that surrounds the inlet 34.

[0083] The centering ring 26, with its ring elements 30 and the O-ring 28, rests against a sealing area 40 of the flange 20. The sealing area 40 defines a circumferential annular surface that faces another flange (not shown) of a vacuum device to be connected. This other flange also includes a corresponding sealing area.

[0084] The flange 20 defines a connection axis 42 concentric with the flange. A connection direction 43 runs along the connection axis 42 and from the vacuum device shown towards the further vacuum device not shown, i.e. in the direction in which the vacuum device is attached to the further vacuum device.

[0085] The sealing area 40 extends in a plane that runs perpendicular to the connecting axis 42. In this example, and generally advantageously, the connecting axis 42 coincides with a rotor axis of the pump.

[0086] Between the sealing area 40 and an axial end of the carrier 36 facing the further vacuum device there is an axial distance 44, which is understood here as positive and is marked with "+".

[0087] In Fig. 7 A turbomolecular pump with a flange 20 according to the invention is shown. A sealing area 40 of the flange 20 is axially offset from an axial end of the vacuum device opposite the connection direction 43. The axial end of the vacuum device is arranged axially between the further vacuum device (not shown) and the sealing area 40 of the flange 20. In this example, the axial end of the vacuum device is formed by both the support 36 and the housing 22, or a section thereof that defines the passage 34, since both have their axial ends at the same axial height.

[0088] The axial distance 44 between the axial end of the vacuum device and the sealing area 40 is therefore, in comparison to the vacuum pump according to Fig. 6 negative and therefore denoted with "-". The sealing area 40 and the flange 20 are thus set back from the axial end of the vacuum device. In other words, the sealing area 40 and the flange 20 are positioned further back than the axial end of the vacuum device. Figs. 6 and 7 The pump is shifted downwards along the housing 22. Conversely, the support 36 and the axial housing end are shifted into the flange connection. This results in a reduced axial length of the pump in the connected state, corresponding to the distance 44.

[0089] In this embodiment, the centering ring 26 does not include a protective or grid element spanning the inlet 34. In such embodiments, where no protective element is necessary, a particularly large saving of axial installation space can be achieved. However, a protective or grid element independent of the sealing element can also be provided, which is attached, for example, to the support 36 and / or the housing 22. In this way, the advantages of a protective element can be combined with the advantage of a significant saving of installation space.

[0090] The Figs. 8 and 9 In contrast, they show a turbomolecular pump with a flange 20 according to the first aspect for a centering ring 26 with grid element 32. This shows Fig. 8 the centering ring 26 before placing it against the sealing area 40, while Fig. 9 shows the centering ring 26 in the applied or installed state.

[0091] An axial distance between the axial end of the vacuum device and the sealing area 40 is again designated 44 and is also negative. However, the distance 44 is significantly smaller than in the embodiment according to Fig. 7 The distance 44 is chosen here so that the centering ring 26 can be placed against the sealing area 40 despite the grid element 32.

[0092] In other embodiments not shown and not belonging to the invention, the distance 44 can also be zero, or at most +2 mm, or at most 3 mm, or at most 4 mm.

[0093] In the embodiment of the Figs. 8 and 9 Thus, compatibility with a sealing element or centering ring 26 with grid element is maintained simultaneously, and yet a, albeit in contrast to Fig. 7 Reduced installation space savings in the axial direction are achieved.

[0094] In Fig. 9It is evident that in the illustrated embodiment, the grid element 32 essentially rests against the axial end of the support 36 and the axial end of the housing. However, embodiments are also conceivable in which a gap remains between the grid element 32 and the axial end of the vacuum device or the support and / or housing end, although the axial space savings may be smaller.

[0095] In the embodiments according to the Figs. 7 to 9 The axial support end 36 coincides with an axial end of the housing 22 facing the other vacuum device. However, this is not mandatory. Rather, the ends in question can also have different axial positions; in particular, the axial housing end can be arranged axially behind the support end from the perspective of the other vacuum device.

[0096] The second aspect is in the Figs. 10 to 14 illustrated. Fig. 10A vacuum device designed as a turbomolecular pump, representing the state of the art. In all embodiments of the Figs. 10 to 14 For example, at least one counter flange 46 is designed as an ISO-F flange.

[0097] The turbomolecular pump according to Fig. 10 The assembly comprises a flange 20, which is arranged on a housing 22. The flange 20 surrounds an inlet 34 of the pump. A support 36 is arranged in the inlet, which carries a functional element 38, which in this case is designed as a stator part of a magnetic bearing. In this embodiment, the support 36 is integrally connected to the housing 22 or the flange 20, but can also be configured, for example, as in the following. Figs. 6 to 9 It should be indicated graphically as a separate part.

[0098] The flange 20 is connected to a mating flange 46, which is part of a housing 48 of another vacuum device (not shown). The flanges 20 and 46 are of type ISO-F. The flanges 20 and 46 have through-holes 50 for fastening elements 52. The through-holes 50 and fastening elements 52 are distributed around the circumference of the bottle 20, 46 about a connecting axis 42 and define the respective fastening points.

[0099] Each connecting element 52 is formed here by a screw 54 with a screw shank 56 and by a corresponding nut 58. The fastening element 52, or the screw 54 in conjunction with the nut 58, clamps the flanges 20, 46 against each other, thereby clamping a sealing element, here a centering ring 26, in the axial direction. An O-ring 28 of the centering ring 26 is compressed up to an axial height corresponding to the ring elements 30 adjacent to the O-ring.

[0100] The forces introduced by the fastening elements 52 and the resulting forces are indicated by several arrows. The fastening elements 52 initially exert a tensile force along a respective fastening axis 60.

[0101] Since the centering ring 26 with its ring elements 30 is to be considered essentially fixed in the axial direction, a certain deformation of the outer flange ends of the flanges 20, 46 towards each other results, creating a lever effect between the fastening element 52 and the centering ring 26.

[0102] The deformation of the flange ends relative to each other can cause problems with regard to vacuum tightness, as the accuracy of the centering ring 26's contact with the sealing areas 40 of the flanges 20 and 46 is generally disrupted. Furthermore, the deformation of the flange 20 can result in a change in position or deformation of the support 36 and thus of the functional element 38, as indicated by the downward-pointing arrow on the connecting axis 42. In the present example, this disrupts the axial positioning of the inner ring of the magnetic bearing and the rotor of the turbomolecular pump, which can lead to increased wear.

[0103] An embodiment according to the second, non-inventive aspect is in Fig. 11 As shown, the flange 20 has several fastening points or axes 60 distributed around its circumference, each with through-openings 50 for corresponding fastening elements 52, by means of which the flange 20 is fastened to the mating flange 46. Furthermore, the flange 20 has a sealing area 40 extending circumferentially with respect to the connecting axis 42 for the contact of a sealing element 26 located between the flanges 20 and 46, which is arranged radially within the fastening points or axes 60 with respect to the connecting axis 42. An axial projection 62 is provided on the flange 20 radially outside the sealing area 40 with respect to the connecting axis 42, providing a contact surface 64 for the additional flange 46.

[0104] Compared with Fig. 10It can be seen that the projection 62 or the contact surface 64 supports the outer ends of the flanges 20, 46 against each other, so that essentially no deformation, primarily no bending around the sealing element or centering element 26, occurs. Thus, on the one hand, the accuracy of the contact of the sealing element 26 with the sealing area 40 is improved, and on the other hand, deformations or changes in position of components connected to the flanges 20, 46, especially on the support 36, are prevented. Therefore, wear is reduced and the service life of the turbomolecular pump shown is increased, since the axial position of the magnetic bearing inner ring and the rotor better corresponds to the design specifications.

[0105] In the example according to Fig. 11The projection 62 and the contact surface 64 extend radially from inside the mounting points 60 to outside the mounting points 60 and even to an outer end of the flanges 20, 46. Alternatively, the projection 62 and the contact surface 64 can also extend only radially inside or outside the mounting points 60, the latter variant being further illustrated below. Figs. 13 and 14 This will be illustrated in more detail.

[0106] In Fig. 12 is the embodiment according to Fig. 11 The perspective view illustrates this in more detail, although the counter flange 46 and fastening elements 52 are not shown. The view of the Fig. 12 This corresponds to a view into the inlet 34 of the pump. The flange 20 with its contact surface 64 is visible.

[0107] Several through-openings 50 are arranged around the circumference of the flange 20. These through-openings 50 are designed here as outwardly open recesses and as elongated holes. However, through-openings 50 that are closed towards the outer edge would also be conceivable. Alternatively, the flanges can be completely free of through-openings, in which case clamp-like fastening elements that grip the flanges are preferably provided.

[0108] The support 36 in the inlet 34 is also clearly visible. In this embodiment, it comprises three webs extending between an inner wall of the housing 22 and a central area of ​​the support 36. The central area carries the functional element 38. Such a support 36 is also referred to as a star.

[0109] Radially within the mounting surface 64, the centering ring 26 with its ring elements 30 and the O-ring 28 is inserted into the flange 20.

[0110] In the system 64, two grooves 66 are formed, which extend from a radially inner end of the system 64 to a radially outer end of the system 64. In the present embodiment, the grooves 66 extend almost exactly radially. A different number of such grooves 66 can also be provided. The grooves 66 allow access for a leak detection gas to the sealing element or centering ring 26 and to the sealing area 40.

[0111] Another embodiment of a vacuum device, again designed as a turbomolecular pump, according to the second aspect, is in Fig. 13 shown. This differs from the embodiment of the Fig. 11 and 12This is achieved by the fact that an axial projection 62 of the flange 20 with its contact surface 64 for the mating flange 46 is arranged only radially outside the fastening points 60. Specifically, the projection 62 and contact surface 64 are arranged only at the outer edge of the flange 20, although an arrangement somewhat further inwards with respect to the outer edge would also be conceivable.

[0112] In the two embodiments according to Fig. 11 and 13 The axial projection 62 is integrally connected to the flange 20, in particular by turning. In the embodiment according to Fig. 14The projection 62 is formed by a separate component. This separate component can, for example, be rigidly connected to the flange 20, for instance via an interference fit between the flange 20 and the downward-facing web of the separate component or projection 62 shown. Alternatively, the separate component can simply rest against the flange 20. Nevertheless, it reliably supports the flange 46 against the flange 20 via its contact surface 64.

[0113] Unless further features of the various embodiments are shown in detail here, it is understood that the features of the other embodiments can be advantageously transferred, insofar as possible. This applies in particular to the vacuum devices according to the Figs. 1 to 5 , 6 and 10 , which, although they represent the state of the art, exhibit specific characteristics that are either already present in the Figs. 7 to 9 and 11 to 14shown but not described in detail or advantageously transferable. Reference symbol list

[0114] 111 Turbomolecular pump 113 Inlet flange 115 Pump inlet 117 Pump outlet 119 Housing 121 Bottom section 123 Electronics housing 125 Electric motor 127 Accessory connection 129 Data interface 131 Power supply connection 133 Flood inlet 135 Sealing gas connection 137 Motor compartment 139 Coolant connection 141 Bottom side 143 Screw 145 Bearing cover 147 Mounting hole 148 Coolant line 149 Rotor 151 Rotation shaft 153 Rotor shaft 155 Rotor disc 157 Stator disc 159 Spacer ring 161 Rotor hub 163 Holweck rotor sleeve 165 Holweck rotor sleeve 167 Holweck stator sleeve 169 Holweck stator sleeve 171 Holweck gap 173 Holweck gap 175 Holweck gap 179 Connecting channel 181 Rolling bearing 183 Permanent magnet bearing 185 Injection nut 187 Washer 189 Insert 191 Rotor-side bearing half 193 Stator-side bearing half 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Support section 203 Support section 205 Radial strut 207 Cover element 209 Support ring 211 Mounting ring 213 Disc spring 215 Emergency orBacking bearing 217Motor stator 219Space 221Wall 223Labyrinth seal . 20 Flange 22 Housing 24 Projection 26 Centering ring 28 O-ring 30 Ring element 32 Grid element 34 Inlet 36 Carrier 38 Functional element 40 Sealing area 42 Connection axis 43 Connection direction 44 Axial distance 46 Counter flange 48 Housing 50 Through opening 52 Fastening element 54 Screw 56 Screw shank 58 Nut 60 Fastening point / axis 62 Projection 64 Contact surface 66 Groove

Claims

1. System comprising a vacuum device, namely a vacuum pump, in particular a turbomolecular pump, and a sealing element (26), wherein the vacuum device comprises: a passage (34), namely an inlet or an outlet; and a flange (20) for connecting the passage (34) of the vacuum device in a vacuum-tight manner to a further vacuum device in a connection direction (43) extending from the vacuum device toward the further vacuum device to be connected along a connection axis (42); wherein the flange (20) has a sealing region (40) extending circumferentially around the connection axis (42) for engagement with a sealing element (26); wherein the sealing element (26) is provided in or for engagement with the sealing region (40) of the vacuum device, wherein the sealing element is formed by a centering ring (26), and wherein the centering ring (26) comprises a deformable sealing member (28), preferably an O-ring, as well as at least one at least substantially rigid holder (30) for the sealing member (28), characterized in that the vacuum device has, radially within the sealing region (40) in the connection direction (43), an end that is axial with respect to the connection axis (42), and that the sealing region (40) of the flange (20) is axially set back relative to the axial end of the vacuum device counter to the connection direction (43).

2. System according to claim 1, characterized in that the axial end of the vacuum device is defined by a part arranged in the passage and / or defining the passage.

3. System according to claim 1 or 2, characterized in that the axial distance (44) between the axial end of the vacuum device and the sealing region (40) is at least 5 mm, in particular at least 10 mm, or the axial distance between the axial end of the vacuum device and the sealing region (40) is at most 3 mm, in particular at most 2 mm.

4. System according to at least one of the preceding claims, characterized in that the sealing element (26) has an axial thickness when installed in the flange connection, wherein the axial distance (44) between the axial end of the vacuum device and the sealing region (40) is at most half the axial thickness of the sealing element (26), or wherein the axial distance (44) between the axial end of the vacuum device and the sealing region (40) is greater than the axial thickness of the sealing element (26).

5. System according to at least one of the preceding claims, characterized in that the flange (20) is connected to a housing (22) of the vacuum device, wherein the flange (20) is preferably formed integrally with the housing (22).

6. System according to any one of the preceding claims, characterized in that the vacuum device is configured as a turbomolecular pump with a magnetic bearing, wherein a support (36) for a component (38) of the magnetic bearing is connected to the flange (20) and / or to a housing (22) of the turbomolecular pump.

7. System according to any one of the preceding claims, additionally comprising a further vacuum device with a further flange, and / or additionally comprising at least one fastening element (60) for fastening the flange (20) of the vacuum device to the further flange of the further vacuum device, wherein the sealing element (26) is in particular configured to be arranged between respective, opposing sealing regions of the flanges.

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