Vacuum pump with magnetic bearings

Abstract

A vacuum pump comprises a pump housing, a rotor comprising pumping elements and having a rotational axis defining an axial direction, and a bearing drive unit. This bearing drive unit, in turn, comprises bearing elements of a magnetic bearing for supporting the rotor, a motor for driving the rotor, and a bearing housing within which the bearing elements and the rotor are arranged. The bearing housing has a fastening connection to the pump housing, which is arranged in the axial direction in a region of the motor.

Description

[0001] The invention relates to a vacuum pump, which is in particular a turbomolecular pump and which comprises a pump housing, a rotor with pump-active elements and a bearing drive unit which contains bearing elements of a magnetic bearing for supporting the rotor and a motor for driving the rotor.

[0002] Such vacuum pumps often incorporate active magnetic bearings, which provide contactless support for the vacuum pump rotor. Such an active magnetic bearing keeps the rotor suspended between stator elements in a predetermined spatial position during operation of the vacuum pump.

[0003] Bearing elements of such a magnetic bearing and an electric motor for driving the rotor are often housed together in a common bearing housing to form a so-called spindle for active magnetic bearings, or active magnetic bearing spindle, which can be integrated into the vacuum pump as a bearing drive unit. This bearing drive unit can be aligned and balanced together with the rotor before they are installed together in the vacuum pump. For stabilization, the bearing drive unit is usually attached to an upper or lower axial end of the bearing drive unit or magnetic bearing spindle, for example, in a lower part of a pump housing of a turbomolecular pump.

[0004] The installation of the bearing drive unit or magnetic bearing spindle and the rotor is usually performed from the top relative to the bottom of the pump housing. In such an installation, routing the required cables for the magnetic bearing elements and the motor is often complex, as the required connections on the bearing drive unit and the motor are often not easily accessible after the magnetic bearing spindle has been inserted. There is a risk of assembly errors, for example, due to pinched cables.

[0005] Furthermore, thermal contact between the bearing drive unit and the pump housing may be insufficient if the housing of the bearing drive unit or magnetic bearing spindle is attached at its upper or lower axial end. The motor for driving the rotor is often located in the center of the bearing drive unit or magnetic bearing spindle, where it is the main source of thermal heating of the bearing drive unit. Therefore, there is usually a certain distance up to the attachment at the upper or lower axial end of the bearing drive unit, which makes it difficult to dissipate heat from the motor via the bearing drive unit attachment. Furthermore, attaching the bearing drive unit or magnetic bearing spindle at its upper or lower axial end can lead to certain vibrations within the vacuum pump.

[0006] An object of the invention is to provide a vacuum pump in which a bearing drive unit or magnetic bearing spindle can be installed with little effort and in which the thermal connection and the vibration behavior of the bearing drive unit are improved.

[0007] This object is achieved by a vacuum pump having the features of claim 1. Advantageous developments of the invention are specified in the subclaims, the description, and the drawings.

[0008] The vacuum pump, which is in particular a turbomolecular pump, comprises a pump housing, a rotor comprising pump-active elements and having a rotational axis defining an axial direction, and a bearing drive unit. This bearing drive unit comprises bearing elements of a magnetic bearing for supporting the rotor, a motor for driving the rotor, and a bearing housing within which the bearing elements and the rotor are arranged. The bearing housing has a fastening connection to the pump housing, which is arranged in the axial direction in a region of the motor.

[0009] The magnetic bearing can be an active magnetic bearing, i.e. a magnetic bearing with such position control of the vacuum pump rotor that the vacuum pump rotor is suspended within the magnetic bearing during operation. In such a suspended state, the vacuum pump rotor has no contact with any other elements of the vacuum pump. Contact with rolling bearings, which are also referred to as emergency or safety bearings, only occurs in unexpected events that deviate from the normal operation of the vacuum pump and in which the rotor moves away from its target position within the magnetic bearing. In addition, the rotor is in contact with the emergency or safety bearings after the vacuum pump is switched off.

[0010] The bearing drive unit can also be referred to as an active magnetic bearing spindle if the magnetic bearing is an active magnetic bearing. Both the bearing elements of the magnetic bearing and the motor or electric motor for driving the rotor can be arranged within the bearing housing of the magnetic bearing spindle.

[0011] The arrangement of the fastening connection in the axial direction in a region of the motor can be designed such that there is at least partial overlap of the motor and the fastening connection in the axial direction. If the fastening connection is formed, for example, by a collar or a projection on an outer side of the bearing housing of the bearing drive unit, there is a specific surface area in the axial direction and in the circumferential direction in which the bearing housing covers part of the outer surface of the motor when the vacuum pump is viewed from the outside in the radial direction.

[0012] In the axial direction, the motor of the vacuum pump can be arranged in a central region of the bearing housing, i.e., at an approximately equal distance relative to the axial ends of the bearing housing or the magnetic bearing spindle. Therefore, the fastening connection between the bearing housing and the pump housing can also be arranged in the axial direction in such a central region of the bearing drive unit or its bearing housing and thus be approximately equally spaced from the two axial ends of the bearing housing. In other words, the axial distance of the fastening connection relative to the center of the bearing housing in the axial direction is smaller than its respective radial distance to the axial ends of the bearing housing. The difference between the respective distances to the axial ends of the bearing housing can thus be smaller than the respective distances of the fastening connection to the axial ends of the bearing housing, i.e.,smaller than the smaller of the two axial distances.

[0013] The vacuum pump is characterized, on the one hand, by the small distance between the motor and the mounting connection of the bearing housing, since the mounting connection is arranged axially approximately at the height of the motor. This allows the heat generated by the motor during operation of the vacuum pump to be transferred more directly to the pump housing than, for example, with a mounting connection at one of the axial ends of the bearing housing. The mounting connection at the height of the motor, for example, in the axial direction in the center of the bearing housing, thus improves the thermal coupling of the vacuum pump motor to the pump housing.

[0014] Furthermore, a mechanically stiffer connection between the bearing drive unit and the pump housing is achieved when the mounting connection of the bearing housing to the pump housing is arranged axially at approximately the same height as the motor. This results in improved vibration behavior of the vacuum pump during operation.

[0015] Additionally, the bearing drive unit can be easily wired if the mounting connection between the bearing housing and the pump housing is located approximately at the height of the motor in the axial direction. For example, with a vertical vacuum pump arrangement, accessible space is available below the bearing drive unit if the mounting connection is located approximately at the height of the motor in the axial direction.

[0016] According to one embodiment, the fastening connection of the bearing housing can be formed with a section of the pump housing that has at least one cooling element. Since the fastening connection is additionally located in the axial direction in the region of the motor, the heat of the motor that arises during operation of the vacuum pump can be dissipated even more efficiently in this embodiment, since the distance between the motor and the cooling element via the fastening connection is small. In this embodiment, therefore, due to the arrangement of the fastening connection of the bearing housing, there is a direct, short connection between the motor of the vacuum pump and the cooling element in a section of the pump housing in both the radial and axial directions.

[0017] The cooling element can be designed as a water cooling system. The portion of the pump housing that has such a water cooling system as the cooling element can have an internal channel or cavity through which cooling water flows. This allows for efficient cooling of the pump housing.

[0018] Alternatively or additionally, the section of the pump housing with which the mounting connection of the bearing housing is formed may have cooling fins. The cooling fins may thus represent a second cooling element in addition to the water cooling to intensify the cooling of the motor.

[0019] Furthermore, if at least one cooling element is designed as a water cooling system, a section of the water cooling system can extend through the bearing drive unit. In this embodiment, a channel or cavity for water cooling thus extends not only through the section of the pump housing in which the fastening connection of the bearing housing of the bearing drive unit is formed, but also through the bearing drive unit or its bearing housing. In such an embodiment, the distance between the motor and the water cooling system is further reduced, allowing for even more efficient cooling of the motor during operation of the vacuum pump.

[0020] According to a further embodiment, the bearing housing may have an outer projection or collar extending outward from an outer edge of the bearing housing in a radial direction perpendicular to the axial direction. The pump housing may accordingly have an inner projection or collar extending inward from an inner edge of the pump housing in the radial direction. In this embodiment, the fastening connection between the bearing housing and the pump housing may be formed by a connection of the outer projection of the bearing housing and the inner projection of the pump housing.

[0021] The fastening connection can therefore be created with little effort between the two projections of the bearing housing and the pump housing. The two projections can be connected to each other, for example, by a screw connection, e.g., a connection using screws extending in the axial direction, or by other means, such as by bonding.

[0022] The inner projection of the pump housing can also be arranged axially between the outer projection of the bearing housing and the pumping elements of the rotor. In this embodiment, the outer projection or collar of the bearing housing and the pumping elements of the rotor are therefore located on opposite sides of the inner projection or collar of the pump housing.

[0023] If the vacuum pump is arranged vertically, i.e., if the rotor's axis of rotation is vertical, the outer projection of the bearing housing of the bearing drive unit or magnetic bearing spindle is arranged below the inner projection of the pump housing in this embodiment. In such a vertically oriented vacuum pump, the bearing drive unit or magnetic bearing spindle can be installed from the underside of the pump, once the vacuum pump rotor has already been installed within the pump housing. With such an implementation of the bearing drive unit, its cabling, i.e., the cabling of the motor and the bearing elements of the magnetic bearing, can be carried out with reduced effort. Furthermore, there is a reduced risk of cables becoming accidentally trapped, since cabling is possible in a clear manner, so to speak, from below.

[0024] If the outer projection of the bearing housing is arranged on the opposite side to the pump-active elements of the rotor with respect to the inner projection of the pump housing, the fastening connection can comprise a screw connection that can extend through the outer projection of the bearing housing in the direction of the pump-active elements. With this screw connection, screws can extend in the axial direction through the outer projection of the bearing housing and with their respective tips into the inner projection of the pump housing. With a vertical arrangement of the vacuum pump or the rotational axis of the rotor, such a screw connection can be produced from below with little effort, since the outer projection of the bearing housing can be easily accessible from the outside.

[0025] Conversely, the outer projection of the bearing housing can be arranged axially between the inner projection of the pump housing and the pumping elements of the rotor. In other words, in this embodiment, the inner projection of the pump housing and the pumping elements of the rotor can be arranged axially on opposite sides of the outer projection of the bearing housing.

[0026] If the vacuum pump is arranged vertically, the outer projection of the bearing housing in this embodiment is located above the inner projection of the pump housing. The bearing drive unit or magnetic bearing spindle is inserted into the pump housing from the top of the vertically oriented vacuum pump and, for this purpose, is previously connected to the rotor of the vacuum pump.

[0027] In this embodiment, the bearing drive unit can be mounted together with the rotor and balanced, for example, by laser balancing. The assembly consisting of the rotor and magnetic bearing spindle or bearing drive unit can then be inserted into the pump housing from above. This simplifies the balancing of the vacuum pump, as the bearing drive unit or magnetic bearing spindle and the rotor are already balanced before they are inserted into the pump housing.

[0028] Furthermore, in this embodiment, the bearing drive unit can have receiving elements for fastening stator elements of one or more pumping stages of the vacuum pump. These receiving elements can be provided, for example, for Holweck stators of the vacuum pump. The Holweck stators can thus first be integrated into or connected to the bearing drive unit or magnetic bearing spindle before further installation together with the rotor of the vacuum pump. This can reduce tolerances when installing or fastening the elements of the vacuum pump. Rotor elements of a Holweck pumping stage of the vacuum pump can therefore be aligned more precisely with respect to the Holweck stators, since these can first be connected and aligned to the bearing drive unit or magnetic bearing spindle.In other words, the bearing drive unit serves as a reference unit for the installation of the Holweck stators and the Holweck rotor elements when they are implemented or installed in the vacuum pump.

[0029] In the present embodiment, in which the outer projection of the bearing housing is arranged in the axial direction between the inner projection of the pump housing and the pump-active elements of the rotor, i.e., for example, with a vertical alignment of the rotor's axis of rotation in the axial direction above the projection of the pump housing, the fastening connection can comprise a screw connection that extends through the inner projection of the pump housing in the direction of the pump-active elements. In this screw connection, screws can extend in the axial direction through the inner projection of the pump housing and with their respective tips into the outer projection of the bearing housing.

[0030] In this and the previously described embodiment, which also provides a screw connection, the direction of extension of the screw connection refers to the direction of movement of the respective screws when they are screwed into the projections of the respective housings to establish the screw connection. In other words, the respective direction of extension of the screw connection runs from a respective head to a respective tip of the screws.

[0031] In an alternative embodiment, the fastening connection can be formed by pressing or shrinking the bearing housing into a portion of the pump housing. Consequently, in this embodiment, projections on the bearing housing or the pump housing are not necessarily required, although the pressing or shrinking can also be performed between the projections described above instead of screw connections. Furthermore, the pressing or shrinking can establish a large-area contact between the bearing housing and the pump housing, which can improve the thermal coupling of the bearing housing, and thus the motor, to the pump housing.

[0032] In a further alternative embodiment, the bearing housing may further comprise an external thread which may be configured to be screwed into an internal thread of a portion of the pump housing. In this embodiment, no projections of the bearing housing or the pump housing are required, although the external thread and the internal thread may also be formed on the projections described above to replace screws. In this embodiment, the axial position of the entire magnetic bearing, i.e. the bearing elements within the bearing drive unit, can be adjusted or displaced in the axial direction by means of the external thread on the bearing housing of the bearing drive unit when the external thread of the bearing housing is rotated in the internal thread of the pump housing. As a result, the axial position of the rotor orThe rotor disks can be adjusted and optimized within the stator elements of turbomolecular pump stages, since the spatial position of the rotor during operation of the vacuum pump or turbomolecular pump is determined by the magnetic bearing. The connection between the internal and external threads can also enable large-area contact between the bearing housing and the pump housing, through which the heat from the vacuum pump motor can be efficiently dissipated when the vacuum pump is in operation.

[0033] In a further alternative embodiment, the bearing housing may in turn have an outer projection extending from an outer edge of the bearing housing in a radial direction perpendicular to the axial direction, and this outer projection may form a portion of the pump housing. In this embodiment, the projection or collar of the bearing housing thus forms an intermediate piece of the pump housing between its upper part, in which the pump-active elements of the rotor may be located, and its lower part of the housing, in which control and connection elements of the vacuum pump are usually located. Such an embodiment allows for a compact design of the vacuum pump.

[0034] Within the bearing drive unit, the motor can further be arranged in the axial direction between the bearing elements of the magnetic bearing. In this embodiment, the motor can be located in the axial direction between bearing elements for radially supporting the rotor, which are thus arranged in the axial direction on both sides of the motor. By distributing the radial bearing elements of the magnetic bearing on both sides of the motor, the vibration behavior of the vacuum pump can be improved. The bearing drive unit can further comprise axial bearing elements or bearing elements for axially supporting the rotor, which are arranged, for example, in the axial direction outside the radial bearing elements and in a region of one axial end or both axial ends of the bearing drive unit.

[0035] The invention is described below by way of example using an advantageous embodiment with reference to the attached figure. It shows schematically: Fig. 1 a vacuum pump with a bearing drive unit according to the invention.

[0036] In Fig. 1 A vacuum pump 100 designed as a turbomolecular pump is schematically shown. The turbomolecular pump 100 comprises turbomolecular pumping stages 102 and Holweck pumping stages 104.

[0037] Furthermore, the turbomolecular pump 100 has a pump housing 110 comprising an upper part 112, an intermediate part 114, and a lower part 116. The pump housing 110 has an inner projection 118 extending from an inner edge of the pump housing 110, the function of which is described in more detail below.

[0038] The turbomolecular pump 100 further comprises a rotor 120 having a rotor shaft 122. The rotor shaft 122 in turn has a rotational axis 124 about which the rotor 120 rotates during operation of the turbomolecular pump 100 and which defines an axial direction within the turbomolecular pump 100, for example in Fig. 1 from bottom to top. The inner projection 118 of the pump housing thus extends inwardly in a radial direction perpendicular to the axial direction and additionally circumferentially around the rotational axis 124 of the rotor 120.

[0039] The rotor 120 further comprises rotor disks 126 associated with the turbomolecular pumping stages 102 and Holweck rotor elements 128 arranged in Fig. 1 are arranged below the rotor disks 126 and extend downwards in the axial direction.

[0040] Stator disks 132 are arranged between the rotor disks 126 in the region of the turbomolecular pumping stages 102. Similarly, the Holweck pumping stages 104 comprise helical Holweck stator elements 134, each of which is assigned to one of the Holweck rotor elements 128.

[0041] The turbomolecular pump 100 further comprises a bearing drive unit or magnetic bearing spindle 140, which comprises bearing elements of a magnetic bearing 141 for supporting the rotor 120. The bearing elements of the magnetic bearing 141 comprise radial bearings 142, which are provided for supporting or aligning the rotor shaft 122 in the radial direction perpendicular to the axis of rotation 124 or to the axial direction. Furthermore, the bearing elements of the magnetic bearing 141 comprise axial bearings 144, which are provided for aligning or supporting the rotor shaft 122 in the axial direction parallel to the axis of rotation 124. The radial bearings 142 and the axial bearings 144 of the magnetic bearing 141 are arranged within a bearing housing 146 of the bearing drive unit 140. The bearing housing 146 has, on its outer edge, an outer projection or projection that runs around the axis of rotation 124.Collar 148, which is provided for fastening the bearing drive unit 140 to the inner projection 118 of the intermediate piece 114 by means of screws 149.

[0042] The bearing drive unit 140 further includes an electric motor 150, which is provided for driving the rotor 120. Within the bearing drive unit 140, the electric motor 150 is arranged in the axial direction between the radial bearings 142 of the magnetic bearing 141. The radial bearings 142 are approximately identical in construction and, viewed conversely, are arranged in the axial direction on both sides of the electric motor 150. By distributing the radial bearings 142 of the magnetic bearing 141 on both sides of the electric motor 150, the vibration behavior of the turbomolecular pump 100 is improved.

[0043] The rotor shaft 122 is rotated by the electric motor 150. A gap 152 is formed between the rotor shaft 122 and the inner circumference of the bearing drive unit 140, so that the rotor shaft 122 and the bearing elements of the magnetic bearing 141, i.e., the radial bearings 142 and the axial bearings 144, do not touch during operation of the turbomolecular pump 100. Instead, the rotor 120 is held in a suspended state by the magnetic bearing 141 during operation of the turbomolecular pump 100. For this purpose, the turbomolecular pump 100 has a position control (not shown). The position control regulates currents in magnetic coils of the radial bearings 142 and the axial bearings 144, thereby maintaining the spatial position of the rotor shaft 122 and the rotor 120 as a whole in a desired, predetermined position. The magnetic bearing 141 is also called an active magnetic bearing because it includes coils of electromagnets and not permanent magnets.

[0044] The bearing drive unit 140 further includes emergency or safety bearings 154, which are designed as rolling bearings. After the turbomolecular pump 100 is shut down, the rotor shaft 122 comes into contact with the safety bearings 154. Furthermore, the rotor shaft 122 can also come into contact with the safety bearings 154 if unexpected events occur during operation of the turbomolecular pump, e.g., if the rotor 120 deviates excessively from its target position due to external influences, in which it is intended to be held by the magnetic bearing 141.

[0045] The turbomolecular pump 100 is characterized in that the outer projection or collar 148 of the bearing drive unit or magnetic bearing spindle 140 is arranged in the axial direction in a region of the electric motor 150 and, by means of the screws 149, forms a fastening connection with the inner projection 118 of the intermediate piece 114 in this axial region of the electric motor 150, and thus a fastening connection with the pump housing 110. This fastening connection is thus approximately equally spaced from both an upper axial end of the bearing drive unit and a lower axial end of the bearing drive unit 140. In other words, the fastening connection of the bearing drive unit 140 to the pump housing 110 is located in the axial direction in a central region of the bearing drive unit or magnetic bearing spindle 140 and not at one of its two axial ends.

[0046] This attachment in the central region of the bearing drive unit 140 allows a stiffer mechanical connection to be established between the bearing drive unit 140 and the pump housing 110 than if a corresponding attachment were arranged at one of the two axial ends of the bearing drive unit 140. This stiffer mechanical connection allows the vibration behavior of the turbomolecular pump 100 to be improved.

[0047] How to Fig. 1As can be seen, the outer projection or collar 148 is arranged on an outer edge of the bearing drive unit 140 adjacent to the electric motor 150. As a result, the electric motor 150 is in direct thermal contact with the outer projection 148 of the bearing drive unit 140. During operation of the turbomolecular pump 100, the bearing drive unit 140 heats up primarily in the area of ​​the electric motor 150. The heat generated by the electric motor 150 during operation of the turbomolecular pump 100 is dissipated directly and efficiently from the electric motor 150 to the pump housing 110 via the outer projection 148, which is directly adjacent to the electric motor 150, and via the fastening connection between the outer projection 148 of the bearing drive unit 140 and the inner projection 118 of the intermediate piece 114 or the pump housing 110.The arrangement of the outer projection 148 of the bearing housing 146 in the central region of the bearing drive unit 140 and the direct proximity to the electric motor 150 thus improves the cooling of the electric motor 150 due to the improved heat dissipation during operation of the turbomolecular pump 100.

[0048] In order to further improve the cooling of the electric motor 150 during operation of the turbomolecular pump 100, the intermediate piece 114 has a first cooling element in the form of a cooling channel 156 through which cooling water flows and can therefore also be referred to as water cooling 156. As in Fig. 1 As can be seen, the distance between the water cooling system 156 and the electric motor 150 is relatively small, which leads to efficient cooling of the electric motor 150. As a second cooling element, the intermediate piece 114 also has cooling fins 158, which further intensify the cooling of the electric motor 150.

[0049] The turbomolecular pump 100 also includes a control unit 160, which has electrical connections (not shown) to both the radial bearings 142 and the axial bearings 144, as well as to the electric motor 150. Since the fastening connection between the bearing drive unit 140 and the pump housing 110 in the form of the outer projection 148, the screws 149, and the inner projection 118 of the pump housing 110 is located in an axial center region of the bearing drive unit, a relatively large free space is available below the outer projection 148 and thus below the bearing drive unit 140 as a whole, in which a wiring of the bearing drive unit 140 for electrical connection to the control unit 160 can be arranged. Due to this free space, the wiring of the bearing drive unit 140 can be implemented efficiently without the risk of cables becoming trapped.

[0050] Furthermore, the turbomolecular pump 100 has a position sensor 170, which is designed as an eddy current sensor and monitors the axial position of the rotor 120 during operation of the turbomolecular pump 100. The position sensor 170 can thus ensure that the rotor 120 is in a desired position in the axial direction and thus in a floating state during operation of the turbomolecular pump 100.

[0051] When assembling the turbomolecular pump 100, a lower cover 180 is first removed in order to fasten the bearing drive unit or magnetic bearing spindle 140 from below in the turbomolecular pump 100 when the turbomolecular pump 100 is as in Fig. 1 shown is arranged vertically. The lower cover 180 is then connected to the lower part 116 of the pump housing 110.

[0052] In an alternative embodiment of the turbomolecular pump (not shown), the outer projection 148 of the bearing drive unit 140 and the inner projection 118 of the intermediate piece 114 can be interchanged in the axial direction, so that the outer projection 148 of the bearing drive unit 140 is located axially above the inner projection 118 of the intermediate piece 114 or of the pump housing 110. In this alternative embodiment, however, the bearing drive unit 140 is then inserted into the turbomolecular pump 100 from above, i.e., from the side of the pump-active elements 126, 128.

[0053] In this embodiment, the bearing drive unit 140 can be mounted together with the rotor 120 and balanced, for example, by laser balancing, in order to then insert the unit comprising the rotor 120 and the magnetic bearing spindle or bearing drive unit 140 from above into the pump housing 110. This simplifies the balancing of the turbomolecular pump 100 because the bearing drive unit or magnetic bearing spindle 140 and the rotor 120 are already balanced before they are inserted into the pump housing 110.

[0054] In this embodiment, the outer projection 148 of the bearing housing 146 may further include receiving elements for the Holweck stator elements 134. This allows for smaller tolerances to occur between the Holweck stator elements 134 and the rotor 120, i.e., between the Holweck stator elements 134 and the Holweck rotor elements 128.

[0055] In a further alternative embodiment, which is also not shown, a fastening connection between the bearing drive unit 140 and the pump housing 110 can be made by pressing or shrinking instead of the connection by means of the screws 149. Furthermore, the bearing housing can alternatively have an external thread that can be screwed into an internal thread of a portion of the intermediate piece 114 and thus of the pump housing 110. Furthermore, the outer projection 148 of the bearing drive unit or magnetic bearing spindle 140 can be designed such that it replaces the intermediate piece 114 between the upper part 112 and the lower part 116 of the pump housing 110. List of reference symbols

[0056] 100Vacuum pump or turbomolecular pump 102Turbomolecular pump stages 104Holweck pump stages 110Pump housing 112Upper part of the pump housing 114Intermediate piece of the pump housing 116Lower part of the pump housing 118Inner projection of the intermediate piece 120Rotor 122Rotor shaft 124Axis of rotation 126Rotor disk 128Holweck rotor element 132Stator disk 134Holweck stator element 140Bearing drive unit or magnetic bearing spindle 141Active magnetic bearing 142Radial bearing 144Thrust bearing 146Bearing housing 148Outer projection of the bearing housing 149Screws 150Electric motor 152Gap between rotor shaft and magnetic bearing 154Emergency or backup bearing 156Water cooling 158 Cooling fins 160 Control unit 170 Position sensor 180 Bottom cover

Claims

1. Vacuum pump (100), in particular a turbomolecular pump, comprising: a pump housing (110), a rotor (120) which comprises pump-active elements (126, 128) and has an axis of rotation (124) which defines an axial direction, a bearing drive unit (140) which comprises: bearing elements (142, 144) of a magnetic bearing (141) for supporting the rotor (120), a motor (150) for driving the rotor (120), a bearing housing (146) within which the bearing elements (142, 144) and the rotor (120) are arranged, wherein the bearing housing (146) has a fastening connection (118, 148, 149) with the pump housing (110), which is arranged in the axial direction in a region of the motor (150).

2. Vacuum pump (100) according to claim 1, wherein the fastening connection (118, 148, 149) of the bearing housing (146) is formed with a portion of the pump housing (110) which has at least one cooling element (156, 158).

3. Vacuum pump (100) according to claim 2, wherein the cooling element (156, 158) is designed as a water cooling (156).

4. Vacuum pump (100) according to claim 3, wherein a portion of the water cooling (156) extends through the bearing drive unit (140).

5. Vacuum pump (100) according to one of claims 2 to 4, wherein the portion of the pump housing (110) with which the fastening connection (118, 148, 149) of the bearing housing (146) is formed has cooling fins (158).

6. Vacuum pump (100) according to one of claims 1 to 5, wherein the bearing housing (146) has an outer projection (148) extending outward from an outer edge of the bearing housing (146) in a radial direction perpendicular to the axial direction, the pump housing (110) has an inner projection (118) extending inward from an inner edge of the pump housing (110) in the radial direction, and the fastening connection (118, 148, 149) between the bearing housing (146) and the pump housing (110) is formed by a connection of the outer projection (148) of the bearing housing (146) and the inner projection (118) of the pump housing (110).

7. Vacuum pump (100) according to claim 6, wherein the inner projection (118) of the pump housing (110) is arranged in the axial direction between the outer projection (148) of the bearing housing (146) and the pump-active elements (126, 128) of the rotor (120).

8. Vacuum pump (100) according to claim 6, wherein the outer projection (148) of the bearing housing (146) is arranged in the axial direction between the inner projection (118) of the pump housing (110) and the pump-active elements (126, 128) of the rotor (120).

9. Vacuum pump (100) according to claim 8, wherein the bearing drive unit (140) has receiving elements for fastening stator elements (134) of one or more pumping stages (104) of the vacuum pump (100).

10. Vacuum pump (100) according to claim 7, wherein the fastening connection (118, 148, 149) comprises a screw connection (149) which extends through the outer projection (148) of the bearing housing (146) in the direction of the pump-active elements (126, 128).

11. Vacuum pump (100) according to claim 8 or 9, wherein the fastening connection (118, 148, 149) comprises a screw connection which extends through the inner projection (118) of the pump housing (110) in the direction of the pump-active elements (126, 128).

12. Vacuum pump (100) according to one of claims 1 to 9, wherein the fastening connection (118, 148, 149) is formed by pressing or shrinking the bearing housing (146) into a portion of the pump housing (110).

13. Vacuum pump (100) according to one of claims 1 to 9, wherein the bearing housing (146) has an external thread which is designed to be screwed into an internal thread of a portion of the pump housing (110).

14. The vacuum pump (100) according to any one of claims 1 to 5, wherein the bearing housing (146) has an outer projection (148) extending from an outer edge of the bearing housing (146) in a radial direction perpendicular to the axial direction, and the outer projection (148) of the bearing housing (146) forms a portion of the pump housing (110).

15. Vacuum pump (100) according to one of claims 1 to 14, wherein the motor (150) is arranged in the axial direction between the bearing elements (142, 144) of the magnetic bearing (141).

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