Rotor for turbo molecular pump, and turbo molecular pump

Abstract

The present disclosure relates to a rotor for a turbomolecular pump with at least one turbomolecular pumping stage, comprising a rotatably mounted shaft having a bore arranged coaxially with an axis of rotation of the shaft, wherein the bore has an axial extent of more than 40%, in particular more than 45%, preferably more than 50% of an axial extent of the shaft, and which has a diameter in a section extending over more than 70%, in particular more than 80%, preferably more than 90% of the axial extent of the bore, exceeding 50%, in particular more than 65%, preferably more than 80% of the diameter of the shaft.

Description

[0001] The invention relates to a turbomolecular pump and a rotor for the same.

[0002] Turbomolecular pumps are vacuum pumps with a fundamentally familiar structure and function, which are versatile and used in various applications and environments in industry and science.

[0003] Turbomolecular pumps are used in particular to create a vacuum in one or more vacuum chambers of a recipient. For this purpose, it is necessary that an inlet side of the vacuum pump is connected to one or more vacuum chambers of the recipient.

[0004] Systems are also known that comprise a receiver containing several vacuum chambers and a pumping chamber connected to them, and a turbomolecular pump housed in the pumping chamber. Such systems serve to evacuate the receiver's vacuum chambers using the turbomolecular pump located in the pumping chamber. A very low pressure, in particular a high vacuum or ultra-high vacuum, can be generated in the vacuum chamber connected to the turbomolecular pump's inlet. The pressure achievable in each subsequent vacuum chamber is higher because each additional vacuum chamber is connected to a separate intermediate inlet of the turbomolecular pump, located downstream of the pump inlet in the pumping direction. Therefore, if several additional vacuum chambers are provided, the achievable pressure in each of them increases successively in the pumping direction.

[0005] The turbomolecular pump can, in particular, be a so-called split-flow pump. Split-flow pumps are generally known. Various embodiments of a split-flow pump are described, among other places, in EP 4 108 932 A1.

[0006] A split-flow pump system typically comprises a turbomolecular pump system with multiple turbomolecular pump stages, followed in the pumping direction by a Holweck pump system with multiple radially nested Holweck pump stages. The rotating pumping components, namely the rotor disks of the turbomolecular pump system and one or more Holweck sleeves of the Holweck pump system, are mounted on a common shaft driven by an electric motor to rotate around an axis of rotation. The pump system of a split-flow pump includes at least one, and usually a plurality, of radial intermediate inlets arranged in the pumping direction (i.e., axially with respect to the axis of rotation). These inlets enable the split-flow pump to simultaneously evacuate multiple vacuum chambers of a receiver and achieve different pressure levels within the vacuum chambers.Split-flow pumps can have their own external housing and be connected to a recipient via this housing. Alternatively, split-flow pumps can be installed within a recipient's pumping chamber. In this case, the components of the split-flow pump can be arranged in their own separate housing. Such a split-flow pump, also known as a cartridge pump, can be handled as a single unit and inserted into the recipient's pumping chamber. However, providing a separate housing is not mandatory. It is also possible to mount the individual components of the split-flow pump directly in the recipient's pumping chamber without a separate housing.

[0007] The vacuum chamber connected to the pump inlet of a turbomolecular pump housed in the pumping chamber is hereinafter also referred to as the high-vacuum chamber. This designation does not imply any limitation to a pressure range achievable in the high-vacuum chamber during operation. For example, due to a generally known differential seal with intermediate suction, pressures in the ultra-high vacuum range can be achieved continuously in the high-vacuum chamber using a sufficiently powerful turbomolecular pump. However, such a design or operation of the system is not mandatory; that is, the system can also be designed or operated in such a way that the pressure achievable in the high-vacuum chamber is higher.

[0008] Such systems can be used, for example, for analytical purposes. Partitions between the vacuum chambers can be equipped with through-holes, so that one or more analytical units can be inserted into the area of ​​the recipient encompassing the vacuum chambers for a given application.

[0009] Sealing arrangements of the type mentioned above, comprising an inner seal and an outer seal surrounding the inner seal, are also generally known and are also referred to as differential seals. In this context, it is also known to evacuate the volume between the seals using a vacuum pump, a process also known as intermediate evacuation. This eliminates the need to seal the interior of the receiver directly against atmospheric pressure. Such a differential seal with intermediate evacuation allows for a very good seal of the receiver, enabling particularly low pressures to be achieved within the receiver.

[0010] According to a first aspect, the present disclosure relates to a rotor for a turbomolecular pump with at least one turbomolecular pumping stage, in particular a split-flow pump. The rotor comprises a rotatably mounted shaft having a bore arranged coaxially with an axis of rotation of the shaft. The bore has an axial extent of more than 40%, in particular more than 45%, preferably more than 50% of the axial extent of the shaft, and has a diameter which, in a section extending over more than 70%, in particular more than 80%, preferably more than 90% of the axial extent of the bore, is more than 50%, in particular more than 65%, preferably more than 80% of the diameter of the shaft.

[0011] In other words, the bore extends relatively deep into the rotor and, at least over large portions of its depth (namely, over more than 70%, in particular more than 80%, preferably more than 90% of the bore's depth), has a large inner diameter relative to the shaft diameter. This bore significantly reduces the rotor's weight without compromising its stability.

[0012] According to one embodiment, the shaft is formed in one piece. The axial extent of the shaft can be smaller than that of the rotor. This can be the case if an axial end of the shaft is provided with an element, for example, to axially secure elements arranged in the bore.

[0013] The pump-active elements of the pump can be mounted on the shaft in a rotationally fixed manner, e.g. any number of rotor discs.

[0014] According to one embodiment, the shaft carries a hub to which a sleeve of a Holweck pump stage can be attached or is attached, in particular wherein the hub is formed integrally with the shaft.

[0015] Preferably, the bore—in the rotor's operating position—extends from the end of the rotor facing the turbomolecular pump's inlet into its interior. Compared to conventional rotors, this shifts the rotor's center of gravity toward its outlet end. In many pumps, this outlet end is supported by a mechanical rolling bearing arrangement, while the inlet end is often supported by a permanent magnet bearing arrangement. This shift in the center of gravity shifts the loads from the permanent magnet bearing arrangement to the more robust mechanical rolling bearing arrangement. Consequently, the permanent magnet bearing arrangement can be designed more simply, resulting in cost advantages.

[0016] The bore can have at least one step. This step can be used for the axial securing of components or functional groups provided in the bore. The bore can also be multi-stage. The axial extent of the bore can be more than 50%, in particular more than 60%, preferably more than 70% of the axial extent of a section of the shaft that carries the at least one turbomolecular pump stage. Preferably, the shaft carries at least two, in particular at least three, and preferably at least four turbomolecular pump stages in the region of the axial extent of the bore.

[0017] According to a second aspect, the present disclosure relates to a rotor - in particular a rotor according to one of the preceding embodiments - for a turbomolecular pump, in particular for a split-flow pump, comprising at least two turbomolecular pumping stages, wherein the rotor comprises a rotatably mounted shaft which carries at least two groups of rotor disks, each forming a rotor-side part of one of the turbomolecular pumping stages, wherein the groups are of identical design.

[0018] A standardized design for the rotor disk assemblies simplifies rotor assembly, minimizing the risk of mix-ups when stacking the disks. This standardization also reduces the number of different components, resulting in cost savings.

[0019] More than two groups of rotor disks can be provided for use in a pump that has a correspondingly higher number of turbomolecular pumping stages. According to one embodiment, all groups are identical.

[0020] A group comprises at least two rotor disks, in particular where these are designed differently.

[0021] According to one embodiment, a group comprises at least two components, one of which forms two rotor disks, in particular the two rotor disks being connected to each other by a sleeve section.

[0022] The components can be designed as single pieces, in particular where the components are manufactured by a machining process.

[0023] According to one embodiment, a spacer is mounted on the shaft between the groups, defining an axial distance between them. The spacer can be sleeve-shaped.

[0024] For example, at least three groups of rotor disks can be provided, with an equal axial distance between the groups. This can be easily ensured by using identical spacers.

[0025] Part of the disclosure relating to the second and third aspects also includes a turbomolecular pump, in particular a split-flow pump, with a rotor according to at least one of the embodiments described above. The turbomolecular pump can be configured according to the embodiments described below. According to a third aspect, the present disclosure relates to a turbomolecular pump with at least one turbomolecular pumping stage, in particular a split-flow pump, which comprises a rotor that is rotatably mounted relative to stationary components of the turbomolecular pump by means of a permanent bearing arrangement, wherein the permanent bearing arrangement has at least one rotor-side bearing arrangement and one static bearing arrangement, and wherein the axial extent of the rotor-side bearing arrangement is greater than that of the static bearing arrangement.

[0026] To balance the rotor, it is mounted in a balancing device that has a static permanent bearing arrangement compatible with the rotor-side bearing arrangement. Especially at the beginning of the balancing process, the rotor exhibits a relatively high imbalance due to manufacturing processes, which places considerable stress on the magnetic bearings. This is particularly true if the rotor is relatively long, as can be the case, for example, with split-flow pumps with multiple pump stages, and / or if the rotor has a bore as described in the first aspect of the disclosure. This imbalance generates high loads during balancing, which must be absorbed by the static permanent bearing arrangement of the balancing device and the rotor-side bearing arrangement. To provide sufficient stiffness to the bearing arrangement, a correspondingly robust design of the bearing components involved is required. This is achieved by a specific axial length of the bearing arrangements.

[0027] After balancing, the rotor's imbalance is significantly reduced, ideally almost completely eliminated. Therefore, when operating a turbomolecular pump with a balanced rotor, the loads to be absorbed by the permanent bearing arrangement—formed by the rotor-side bearing arrangement and the pump's static bearing arrangement—are considerably lower than those occurring during the balancing process. Consequently, the permanent bearing arrangement can be simpler in design than the combination of rotor-side bearing arrangement and static permanent bearing arrangement used for balancing.

[0028] Since changing the rotor-side bearing arrangement after balancing almost inevitably leads to an undesirable increase in the rotor's imbalance, it remains unchanged. However, the pump's static bearing arrangement can be simpler or shorter than the balancing unit's static bearing arrangement. This, in turn, means that expensive material required for the permanent bearing arrangement can be saved.

[0029] The rotor-side and static bearing arrangement of the pump can each be formed by a plurality of permanent magnetic rings arranged one behind the other in an axial direction, wherein the number of housing-side rings is smaller than the number of rotor-side rings.

[0030] According to one embodiment, the permanent bearing device is arranged in the area of ​​an inlet of the turbomolecular pump.

[0031] The ends of the rotor-side bearing arrangement and the static bearing arrangement of the pump facing the inlet can be arranged in the same plane. It is also possible for the ends of the rotor-side bearing arrangement and the static bearing arrangement facing away from the inlet to be arranged in the same plane. In principle, the (shorter) static bearing arrangement can be positioned anywhere between the planes defined by the ends of the (longer) rotor-side bearing arrangement, preferably in a central position between the planes.

[0032] According to a fourth aspect, the present disclosure relates to a turbomolecular pump, in particular according to at least one of the preceding embodiments, comprising a pump inlet, a pump outlet, and a pumping system acting in a pumping direction from the pump inlet to the pump outlet, which has at least a first Holweck pumping stage and a second Holweck pumping stage following in the pumping direction, which are in particular arranged radially one inside the other. Furthermore, at least a first intermediate inlet, which is arranged upstream of or in the region of the first Holweck pumping stage in the pumping direction, and at least a second intermediate inlet located between the first and the second Holweck pumping stage are provided.

[0033] The first intermediate inlet can be located – viewed in the direction of pumping – between the last turbomolecular pump stage and the first Holweck pump stage.

[0034] An intermediate inlet arranged "in a region of the first Holweck pump stage" is understood to be at least one opening that allows gas to flow into the Holweck pump stage between an inlet and an outlet. For example, the first intermediate gas inlet is arranged in a section of a component of the first Holweck pump stage (e.g., stator sleeve) that is provided with pump-active components of the stage (e.g., Holweck grooves), so that gas can flow into the first Holweck pump stage in a radial direction.

[0035] According to a fifth aspect, the present disclosure relates to a turbomolecular pump, in particular according to at least one of the preceding embodiments, comprising a pump inlet, a pump outlet, and a pumping system acting in a pumping direction from the pump inlet to the pump outlet, which has at least a first Holweck pumping stage and a second Holweck pumping stage following in the pumping direction, which are in particular arranged radially one inside the other. Furthermore, at least one intermediate inlet is provided between the first and the second Holweck pumping stage, wherein the intermediate inlet comprises a radial opening in a wall section extending in the axial direction, which adjoins a pump-active section of a Holweck stator of the first Holweck pumping stages.

[0036] The Holweck stator can include a sleeve that has both the wall section and the pump-active section.

[0037] According to one embodiment, the wall section is formed on a sleeve, which is a component separate from the Holweck stator. This sleeve can serve as a kind of spacer between a lower part that houses the motor stator of a drive motor for powering the pump system and the Holweck stator.

[0038] It is also conceivable that the wall section is formed on a sleeve-like section of the lower part that extends in the axial direction. The sleeve-like section can be formed integrally with the lower part.

[0039] An axial end of a Holweck rotor of the first and / or the second Holweck pump stage can be arranged at the axial height of the radial opening.

[0040] According to one embodiment, the intermediate inlet is the only intermediate inlet of the turbomolecular pump or the last intermediate inlet of the turbomolecular pump viewed in the pumping direction.

[0041] In particular, the Holweck stator of the second Holweck pump stage is designed on a lower part that accommodates a motor stator of a drive motor for driving the pump system.

[0042] According to one embodiment, a sealing arrangement for sealing the outlet side of the turbomolecular pump against the atmosphere is arranged axially from the pump inlet below the radial opening. This means that the intermediate inlet – especially if it is the last intermediate inlet of the turbomolecular pump viewed in the pumping direction – no longer needs to be sealed separately against the atmosphere, as has been the norm until now.

[0043] According to a sixth aspect, the present disclosure relates to a turbomolecular pump, in particular according to at least one of the preceding embodiments, comprising a pump inlet, a pump outlet, a pumping system acting in a pumping direction from the pump inlet to the pump outlet, which has at least a first Holweck pump stage and a second Holweck pump stage following in the pumping direction, which are in particular arranged radially one inside the other, and at least one intermediate inlet located between the first and the second Holweck pump stage. An outlet-side end of the first Holweck pump stage, an inlet-side end of the second Holweck pump stage and - if present - the radial opening of the intermediate inlet open into an annular collecting chamber, the axial extent (H) of which is at least 50%, in particular at least 75%, preferably at least 100% of its width (B).

[0044] A comparatively large collection space makes it possible to utilize the potentially available suction capacity in the area between the Holweck pump stages as effectively as possible.

[0045] A radially inner side wall of the collection chamber can be formed by a lower part of the turbomolecular pump that houses a motor stator of a drive motor for powering the pump system. Additionally or alternatively, a radially outer side wall of the collection chamber can be formed at least partially, and in particular completely, by the wall section.

[0046] For example, the collection chamber has, at least in sections, a width that corresponds to a distance between the base of a groove of a pump-active groove of the first Holweck pump stage and the base of a groove of a pump-active groove of the second Holweck pump stage.

[0047] The collecting channel can have a cross-sectional geometry that is essentially constant in the circumferential direction.

[0048] A lower part of the turbomolecular pump, which accommodates a motor stator of a drive motor for driving the pumping system, may have at least one axial outlet channel that is connected to an outlet-side end of the pumping system and the pump outlet.

[0049] According to a seventh aspect, the present disclosure relates to a turbomolecular pump, particularly according to one of the preceding embodiments, comprising a pump inlet, a pump outlet, and a pumping system operating in a pumping direction from the pump inlet to the pump outlet. Furthermore, a lower part with a receiving chamber is provided, which receives a motor stator of a drive motor for driving the pumping system. The lower part has at least one channel that communicates with an outlet-side end of the pumping system and with a section of the receiving chamber that is axially bounded by the motor stator and faces away from the outlet-side end of the pumping system. This channel may include a groove in a side wall of the receiving chamber. The channel may, for example, also be a bore. It is possible to provide two or more channels, which may be identical or differently configured.

[0050] Cables may be routed through the channel, at least in sections, e.g. a data cable from a sensor device located inside the pump, whose signals are transmitted to a control unit of the turbomolecular pump.

[0051] The channel also allows pumped gas to flow from the outlet end of the pump system to the part of the receiving chamber behind the motor stator, for example, to equalize pressure. The channel can also be connected – directly or indirectly (e.g., via another channel, particularly the axial outlet channel) – to the pump outlet. This can help optimize the discharge of the pumped gas.

[0052] According to an eighth aspect, the present disclosure relates to a turbomolecular pump - in particular according to one of the preceding embodiments - comprising a pump inlet, a pump outlet, a pumping system effective in a pumping direction from the pump inlet to the pump outlet, comprising at least a first Holweck pumping stage and a second Holweck pumping stage following in the pumping direction, which are in particular arranged radially inside one another, and at least an intermediate inlet located between the first and the second Holweck pumping stage.Furthermore, a closing element is provided which covers the turbomolecular pump in an assembled state at least partially in the axial direction and which comprises at least one channel for establishing a connection between the intermediate inlet and a vacuum chamber of a recipient, wherein the closing element has a first shape feature which can be brought into engagement with a second shape feature which is complementary to the first shape feature and which is provided on the recipient.

[0053] A system with a pump according to the eighth aspect can comprise a receiver having a housing with at least one pump chamber for accommodating a turbomolecular pump and with several vacuum chambers. The receiver can have a second shape feature that can be brought into engagement with the first shape feature, which is provided on the end element and is designed to be complementary to the second shape feature.

[0054] The end element can be a lower part of the turbomolecular pump that houses a motor stator of a drive motor for powering the pumping system. The lower part can include both the intermediate inlet and the channel. It can be connected to the receiver directly or indirectly.

[0055] According to one embodiment, the end element is a separate component that forms a cover, securing the turbomolecular pump within the pumping chamber. In this case, the channel in the cover is connected, for example, to a channel in the lower part, which in turn is connected to the intermediate inlet.

[0056] The shape features facilitate mounting the pump on or in the receiver.

[0057] The shape features can also have geometric properties that, for example, ensure the pump is mounted at an exact angle (e.g., protrusions that engage in complementary recesses when mounted).

[0058] According to a ninth aspect, the present disclosure relates to a turbomolecular pump – in particular according to one of the preceding embodiments – comprising a pump inlet, a pump outlet, a pumping system acting in a pumping direction from the pump inlet to the pump outlet, and a lower part that accommodates a motor stator of a drive motor for driving the pumping system and that has at least one outlet channel that is connected to an outlet-side end of the pumping system and to the pump outlet. The outlet channel has an axially extending channel section and an inclined channel section that extends obliquely to the axial direction.

[0059] The axial direction corresponds to a direction parallel to a rotation axis of a rotor of the turbomolecular pump.

[0060] The angle of inclination of the inclined channel section - i.e., an angle between the longitudinal extent of the inclined channel section and the axial direction - can be between 75° and 35°, in particular between 65° and 45° (e.g. 55° + / - 5°).

[0061] In particular, the inclined channel section extends radially outwards from the axial channel section. Preferably, it is arranged downstream of the axial channel section.

[0062] A lateral "deviation" of the outlet channel by means of the inclined channel section creates space for additional functional components in the lower part of the pump (e.g. for a lubricant reservoir), and such a design of the outlet channel also offers advantages in terms of fluid dynamics.

[0063] For all embodiments, the pumping system can have any number of turbomolecular pump stages and / or Holweck pump stages. Preferably, a Holweck stator of the last Holweck stage of the pumping system is formed on the lower part. The turbomolecular pump is preferably a split-flow pump.

[0064] In its simplest form, a turbomolecular pump stage comprises a rotor element (e.g., rotor disk) and a stator element (e.g., stator disk).

[0065] The various aspects described above, along with their embodiments and features, can be combined as needed to create a pump particularly suitable for a given application. In particular, the described rotors and their modifications can be used in the turbomolecular pump embodiments described above. The features of the various turbomolecular pump embodiments can also be combined as required.

[0066] Unless explicitly described otherwise, in the context of this disclosure it is to be understood that the axial direction is a direction extending parallel to an axis of rotation of the rotor.

[0067] The accompanying drawings illustrate the structure of a known turbomolecular pump and examples of its implementation according to the aspects explained above. They show: 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. 2 Section 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. 2The section line CC shown, Fig. 6 schematically shows a system with a receiver and a turbomolecular pump according to the prior art, Fig. 7 schematically shows a possible embodiment of a rotor according to the first aspect of the present disclosure, Fig. 8 schematically shows a possible embodiment of a rotor according to the second aspect of the present disclosure, Fig. 9 schematically shows a possible embodiment of a rotor according to the third aspect of the present disclosure, and Figs. 10 to 12 schematically show further possible embodiments of a turbomolecular pump according to further aspects of the present disclosure.

[0068] The following will be explained in more detail below to aid understanding, using the Figs. 1 to 5An exemplary embodiment of a known turbomolecular pump 111 is described in order to explain the basic operating principle of turbomolecular pump stages, Holweck pump stages and other components (e.g., the bearing of a pump rotor). These concepts can also be applied analogously to split-flow pumps.

[0069] The in Fig. 1 The 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.

[0070] 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 (see also Fig. 3 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.

[0071] There are also turbomolecular pumps that do not have such an attached electronics housing, but are connected to external drive electronics.

[0072] 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 The gas pumped by the pump can be introduced into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111. Two coolant connections 139 are also arranged in the lower part 121, one of which serves as an inlet and the other as an outlet for coolant that can be directed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

[0073] 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. 1 As shown. It is also possible to implement embodiments of the vacuum pump in which the underside 141 can be arranged facing sideways or upwards instead of downwards. In principle, any angle is possible.

[0074] Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in a standing position.

[0075] On the underside 141, which is in Fig. 2As 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.

[0076] Mounting holes 147 are also arranged on the underside 141, via which the pump 111 can be attached to a support surface, for example. This is not possible with other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here.

[0077] 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.

[0078] Like the sectional views of the Figures 3 to 5 As 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.

[0079] A rotor 149 is arranged in the housing 119, which has a rotor shaft 153 rotatable about a rotation axis 151.

[0080] 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.

[0081] The vacuum pump also includes Holweck pump stages arranged radially within one another and connected in series to effectively pump the pump. Other turbomolecular vacuum pumps exist (not shown) that do not have Holweck pump stages.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] The aforementioned pump-active surfaces of the Holweck stator sleeves 167, 169 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.

[0086] 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.

[0087] 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 fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), an injection screw may be provided instead of an injection nut. Since different designs are thus possible, the term "injection tip" is also used in this context.

[0088] The operating fluid reservoir comprises several stacked absorbent discs 187, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

[0089] 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.

[0090] 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 repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be radially supported. 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 201. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 151 in one direction 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.

[0091] 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 and thus prevent 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] To explain the known background of the present revelation, Fig. 6 A schematic representation of a prior art system is shown. The known system comprises a receiver 11 (only partially shown) with a pump chamber 15 and a turbomolecular pump 17 inserted into the pump chamber 15. The lower portion of the figure, including the forevacuum-side section of this system, is not shown for the sake of simplicity.

[0096] The turbomolecular pump 17 is a split-flow pump whose pumping system comprises a turbomolecular pumping system 29 and a Holweck pumping system 31, which is arranged downstream of the turbomolecular pumping system 29 in a pumping direction indicated by arrows in the figure. The turbomolecular pumping system 29 comprises a plurality of turbomolecular pumping stages 29a, 29b arranged successively in the pumping direction. For the sake of simplicity, only two turbomolecular pumping stages 29a, 29b are shown in the figure. Preferably, the turbomolecular pump 17 has a larger number of, for example, three, four, five, or six successive turbomolecular pumping stages.

[0097] The Holweck pump system 31 comprises two radially nested Holweck pump stages 31a, 31b. Such an arrangement of Holweck pump stages 31a, 31b is also referred to as a nested Holweck pump system.

[0098] The rotating system of the turbomolecular pump 17 comprises a rotor 50 with a shaft 51 rotatably mounted about a rotational axis 53, on which rotor disks 55 of the turbomolecular pumping stages 29a, 29b and a Holweck sleeve 57 for the Holweck pumping stages 31a, 31b, supported by a hub 59, are attached.

[0099] For the Holweck pumping system 31, the Holweck stators 61, each interacting with the Holweck sleeve 57 to provide pumping effect, are shown. The Holweck stators 61 are shown.

[0100] Rotor disks 55 of the turbomolecular pump stage 29a, 29b, which interact effectively for pumping purposes, are not shown for the sake of simplicity.

[0101] The aforementioned stator elements of the turbomolecular pump 17 can be arranged together with the rotating system and other components of the turbomolecular pump 17 in a separate, common housing, which is not shown in the figure. As mentioned above, such a vacuum pump, also referred to as a cartridge pump, can be handled as a single unit and inserted into the pumping chamber 15 of the receiver 11. However, providing such a cartridge housing is not mandatory. The rotating system and the aforementioned stator elements, as well as other components of the turbomolecular pump 17, can also be arranged in the pumping chamber 15 of the receiver 11 without a separate housing. Such a configuration, in which the receiver 11 essentially forms the pump housing, is also referred to as an integrated or fully integrated turbomolecular pump arrangement.

[0102] The turbomolecular pump 17 has an axial inlet 27, which is formed by the axial access to the pumping chamber 15 of the recipient 11 and thus leads to the first turbomolecular pumping stage 29a. The outlet of the turbomolecular pump 17 is not shown.

[0103] The axis of rotation 53 of the turbomolecular pump 17 runs parallel to a longitudinal axis of the pump chamber 15. With respect to this longitudinal axis, and thus with respect to the axis of rotation 53 of the turbomolecular pump 17 when installed in the pump chamber 15, there is an arrangement of axially successive vacuum chambers radially adjacent to the pump chamber 15, of which three vacuum chambers 19, 21, and 23 are shown here. These vacuum chambers are bounded externally by a wall 39 of the housing 13 and, towards the pump chamber 15, by an inner wall section 69 of the housing 13. The uppermost vacuum chamber 19 in the figure, which is also referred to as the high-vacuum chamber (as mentioned above) and is connected to the pump inlet 27, is further bounded by a cover 45 that closes an access opening 13a of the housing 13.Between the vacuum chambers are partition walls 26 running perpendicular to the longitudinal axis of the pump chamber 15, each of which may be provided with a through-opening, so that, for example, an analysis unit not shown in the figure can be introduced into the arrangement of vacuum chambers.

[0104] While the high-vacuum chamber 19 is connected to the pump inlet 27, i.e., to the axial access to the pump chamber 15, the other vacuum chambers 21 and 23 each have an outlet 21a and 23a, respectively, which is formed in the inner wall section 69 and opens into the pump chamber 15. These outlets 21a and 23a connect the other vacuum chambers 21 and 23 to an intermediate inlet 33 and 35 of the turbomolecular pump 17. The intermediate inlet 33 connected to the first additional vacuum chamber 21 is located between two successive turbomolecular pump stages 29a and 29b, and the intermediate inlet 35 connected to the second additional vacuum chamber 23 is located between a turbomolecular pump stage 29b and the first Holweck pump stage 31a.

[0105] In the case of an integrated or fully integrated arrangement of the turbomolecular pump 17 as described above, i.e., if it does not have its own housing, the outlets 21a, 23a simultaneously form the intermediate inlets 33, 35 of the turbomolecular pump. Otherwise, the intermediate inlets 33, 35 are formed in the housing of the turbomolecular pump 17 and, in the operating state accommodated in the pump chamber 15, are aligned with the outlets 21a, 23a.

[0106] As mentioned above, the lower part of the system is not shown in the figure. In fact, the receiver 11 comprises more than two further vacuum chambers 21, 23. A third vacuum chamber is partially shown in the figure. By way of example, a total of six further vacuum chambers can be provided, each connected to an intermediate inlet of the turbomolecular pump 17, wherein the first four intermediate inlets are each located between two successive turbomolecular pump stages, the fifth intermediate inlet is located between the last turbomolecular pump stage 29b and the first Holweck pump stage 31a, and the sixth intermediate inlet is arranged in the region of the transition between the two Holweck pump stages 31a, 31b.

[0107] During operation of the described system, the turbomolecular pump 17 generates a vacuum in the individual vacuum chambers 19, 21, 23, with the lowest pressure being generated in the high vacuum chamber 19 and the pressure in the vacuum chambers increasing successively in the pumping direction.

[0108] As already mentioned, this is based on Fig. 6 The described design of the receiver 11 with a plurality of superimposed vacuum chambers 19, 21, 23 and the interaction of the receiver 11 with a split flow pump 17 included in the pump chamber 15 is generally known.

[0109] The aforementioned analysis unit can be inserted, for example, through the access opening 13 of the receiver housing 11. The access opening 13a is bounded by a circumferential end face of the aforementioned housing wall 39. The access opening 13a is closed during operation by the cover 45 resting on this end face. It is known to ensure sealing against the environment by means of a differential seal (not shown), i.e., by a sealing arrangement between the end face of the housing wall 39 and the side of the cover 45 facing this end face. The sealing arrangement can comprise an inner seal surrounding the access opening 13a and an outer seal surrounding the inner seal.Furthermore, it is generally known that the sealing effect of such a sealing arrangement is improved if a negative pressure is generated in the volume between the two seals, which lies between the external atmospheric pressure on the one hand and the low pressure, for example an ultra-high vacuum, in the vacuum chamber 19 bounded by the cover 45 on the other. For this purpose, it is known in such systems to use the vacuum pump incorporated in the receiver for intermediate extraction of the differential seal.

[0110] According to the first aspect of the invention, the weight of the rotor 50 is reduced by designing it, at least in sections, as a hollow shaft. In the Fig. 7In the illustrated embodiment, the rotor 50 has an axial bore 300, which extends from an inlet-side end 302 into a shaft 51 of the rotor, i.e., from an end facing an inlet of a pump in which the rotor 50 is installed. The bore 300 is comparatively large, but not so large as to compromise the stability of the shaft 51. A diameter D1 of the bore is more than 50%, in particular more than 65%, preferably more than 80% of a diameter D of the shaft 51. It further has an axial extent A1 that is more than 40%, in particular more than 45%, preferably more than 50% of an axial extent A of the shaft 51.

[0111] The bore 300 shifts the center of gravity of the rotor 50 towards an end 304 of the shaft 51 furthest from the inlet, which is supported, for example, mechanically by means of a rolling bearing. A mechanical bearing is more robust than a permanent magnet bearing, which is typically used in the area of ​​the end 302 of the rotor 50 closer to the inlet. The measure of introducing a central bore 300 into the shaft 51 therefore not only offers the advantage of saving material and weight, which in itself reduces the loads that the bearings of the shaft 51 have to bear. The shift in the center of gravity also shifts the loads to a bearing area that can easily withstand high loads. The design of the permanent magnet bearing can thus be simplified.

[0112] The bore 300 can be stepped to form shoulders on which functional components, such as components of a permanent magnet bearing and / or a catch or emergency bearing, can be axially supported. Thus, the diameter of the bore 300 can be designed to decrease (stepwise) from the inlet-side end 302 to the inlet-removed end 304, unlike the one shown. However, it has proven advantageous for the bore diameter to be large over a wide range (more than 70%, in particular more than 80%, preferably more than 90% of the axial extent of the bore), i.e., more than 50% of the shaft diameter.

[0113] In the illustrated embodiment, the shaft 51 carries five turbomolecular stages 29x, four of which are located in the region of the axial extent of the bore 300. Only the lowest turbomolecular stage 29x is arranged in an axial section where the shaft 300 is solid. It is understood, however, that the bore 300 could be shorter or deeper.

[0114] The stator-side elements of the turbomolecular pump stages 29x are not shown for the sake of simplicity. This also applies to Fig. 8 .

[0115] Below the lowest turbomolecular pump stage 29x, a hub 32a is provided, which can be formed integrally with the shaft 51 or be a separate component that is rotationally fixed to it. The hub 32a carries a Holweck or rotor sleeve 32, which forms a rotor-side part of a Holweck pump stage.

[0116] Fig. 8Figure 50 shows a portion of a rotor 50 to illustrate an embodiment according to the second aspect of this disclosure. The rotor 50 comprises a shaft 51, which in this example carries two turbomolecular pump stages 29x. Each turbomolecular pump stage 29x is formed by a group of rotor disks 310a, 310b. The groups are identical in the two turbomolecular pump stages 29x shown as examples. They each comprise one rotor disk 310a and two rotor disks 310b. The rotor disks 310b can be of identical or different construction. It is understood that the design of the rotor disks 310a, 310b of the groups can be selected as required. However, to facilitate the assembly of the rotor 50, the groups are identical in construction.The advantages associated with easier assembly and a reduction in the number of different components may outweigh any disadvantages that may arise from using uniform turbomolecular pump stages 29x at different pressure levels.

[0117] The rotor disks 310b can be connected to each other via a sleeve section 312b. In particular, the rotor disks 310b and the sleeve section 312b are formed in one piece; for example, the corresponding component is manufactured in a machining process.

[0118] The rotor disk 310a can also be connected to a sleeve section 312a, which facilitates pressing it onto the shaft 51.

[0119] A spacer sleeve 314 is provided between the two groups of rotor disks 310a, 310b, which, for example, after the application of the Fig. 8The lower turbomolecular pump stage 29x is pushed or pressed onto the shaft 51 before the other turbomolecular pump stage 29x follows. The desired distance between the turbomolecular pump stages 29x can be easily adjusted using the spacer sleeve 314.

[0120] In rotors with more than two turbomolecular pump stages 29x, identical or different spacer sleeves 314 with identical or different axial extensions can be used between the individual groups of rotor disks 310a, 310b, depending on requirements.

[0121] Fig. 9Figure 1 shows part of an inlet-side end 302 of a rotor 50, which is mounted on a support section 203. The support section 203 is in turn rigidly connected to a pump housing (not shown) via a radial strut 205. The support section 203 carries a housing-side or static bearing arrangement 302, which, together with a rotor-side bearing arrangement 322, forms a permanent bearing arrangement 324 to magnetically mount an inlet-side end 302 of the rotor 50, thus ensuring virtually lossless stability.

[0122] As explained at the outset, the magnetic bearing used to balance the rotor 50 must exhibit particularly high stiffness, since the rotor 50 still has a comparatively large imbalance after manufacturing. Once this imbalance is removed, a less stiff bearing can be provided for the operation of the rotor 50 in a pump, since fewer loads need to be absorbed due to the significantly reduced imbalance. However, since modifying the rotor-side bearing arrangement 322 could cause the imbalance of the rotor 50 to increase again, it is not modified. It is possible, however, to dimension a static bearing arrangement 320 smaller in order to achieve cost advantages. This ultimately results in the static bearing arrangement 320 having a smaller axial extent than the rotor-side bearing arrangement 322 (third aspect of the present disclosure).In the specific case shown, this means that fewer ring magnets 326 are used on the housing side than on the rotor side.

[0123] Based on the Fig. 10 An embodiment of the fifth aspect of the present disclosure is explained below. A lower part of a turbomolecular pump 17 is shown, comprising a rotor 50 with several turbomolecular pump stages 29x (two pump stages 29x are shown) and two nested Holweck pump stages 31x. The pump 17 is inserted into a pumping chamber 15 of a receiver 11, which comprises a housing 13. For the sake of simplicity, stator-side components of the turbopump stages 29x and other components not essential for describing the aspects of the present disclosure are not shown.

[0124] The recipient 11 has a plurality of vacuum chambers 19x, two of which are partially in Fig. 10The diagram shows that gas from the upper vacuum chamber 19x can flow to the first Holweck stage 31x through an intermediate inlet 35x (gas flow GS1). Downstream of the first Holweck pump stage 31x, gas is again supplied to the pumping system of the pump 17 (see arrow GS2). This gas is provided through an intermediate inlet 35y and a radial opening 35z in a section of a stator sleeve 330. This section adjoins a pump-active part of the stator sleeve 330 in the axial direction downwards. The pump-active part of the stator sleeve 330 is symbolized by the short lines projecting radially inwards. These lines define Holweck grooves 332, which, during operation, together with the Holweck or rotor sleeve 32, generate a pumping action.

[0125] The gas stream GS2 thus enters the pumping system at or below a reversal point of the gas stream G1, which has passed through the first Holweck pumping stage 31x. Subsequently, the combined streams GS1 and GS2 pass through the second Holweck stage 31x and are pumped into an outlet chamber 334, which represents an outlet-side end of the pumping system – comprising the turbomolecular pumping stages 29x and the Holweck stages 31x.

[0126] Since the stator sleeve 330 extends relatively far downwards in the axial direction, the pump chamber 15 can be sealed against the atmosphere below the radial opening 35z. Because the radial opening 35z is connected to the vacuum chamber 19x, which has the highest pressure, the sealing arrangement, symbolized here by two sealing rings 336, can be simpler. This is because there is no intermediate inlet below the sealing arrangement shown, thus eliminating the need for a separate seal for the corresponding intermediate inlet. This, in turn, results in cost savings.

[0127] One of the sealing rings 336 acts between the housing 13, the stator sleeve 330 and a base 339b of a lower part 339 of the pump 17. The other sealing ring 226 is arranged in a groove in the base 339b and acts between it and the stator sleeve 330.

[0128] In the Fig. 10In the illustrated embodiment, the pump 17 thus has two Holweck stages 31x and two associated intermediate inlets 35x, 35y (fourth aspect of the present disclosure). The intermediate inlet 35x opens into a region between the last turbomolecular pump stage 29x and the first Holweck stage 31x, i.e., into a region upstream of the first Holweck stage 31x. Unlike the illustration shown, it could also establish a fluid connection between one of the vacuum chambers 19x and the first Holweck stage 31x in a pump-active part of the stator sleeve 330. For example, it would be conceivable to provide at least one radial opening for this purpose in a section of the stator sleeve 33 that carries the Holweck groove 332 and is located above the radial opening 35z. Gas can be introduced into a region between the Holweck stages 31x through the second intermediate inlet 35y.

[0129] The gas pumped into the outlet chamber 334 can be discharged through an outlet channel 338 extending in an axial direction. It is understood that several outlet channels 338 can also be provided.

[0130] The outlet channel 338 leads through a central section 339a of the lower part 339, which extends axially from the base 339b, and through the base 339b. It can be connected to a forevacuum port of the pump 17 (not shown).

[0131] Additionally or alternatively, a channel 340 may be provided in the central section 339a according to the seventh aspect of the present disclosure. It connects the outlet chamber 334 with a section of a receiving chamber 344, which receives a motor stator 242 of a drive motor of the rotor 50 and other components not shown (e.g., a bearing arrangement), the section being oriented away from the outlet chamber 334, i.e., in Fig. 10The channel 340 is located below the stator 342. The channel 340 can also be a groove in the wall of the receiving chamber 344. It is understood that multiple channels 340 and / or grooves may be provided.

[0132] Channel 340 can be used to route cables connecting sensor devices, e.g., temperature sensors, inside pump 17 to a control unit (not shown) of pump 17. Additionally, it provides a fluid path for gas from outlet chamber 334. A corresponding gas flow can be used for pressure equalization and / or, if channel 344 is connected – directly or indirectly – to outlet channel 338, for the removal of the pumped gas.

[0133] Fig. 10Figure 6 also shows an embodiment according to the sixth aspect of the present disclosure. The outlet end of the first Holweck stage 31x and the inlet end of the second Holweck stage 31x, as well as the intermediate inlet 35y, open into a collecting chamber 400, which is designed to be comparatively large in order to utilize the potential of the pumping speed in the area between the Holweck pump stages as efficiently as possible. For this purpose, the central section 339a is designed to be slimmer in this area than in conventional pumps. It transitions into the base 339b with an incline and / or curvature (not shown).

[0134] An axial extent or height H of the collecting chamber 400 is a distance from a free end of the rotor sleeve 32 to the base 339b. Alternatively, a distance from an end of the pump-active area of ​​the Holweck stator closest to the base 339 to the base 339b can be used. The width B can, for example, be a radial distance from side walls of the collecting chamber 400, here a distance between the stator sleeve 330 and a vertical wall section of the central section 339a. In the example shown, the ratio H:B is approximately 2:1. If the lower end of the left Holweck pump stage 31x and the distance of the sleeve 330 from the beginning of the slope are used as a basis, the ratio is even approximately 3:1. According to the sixth aspect of the present disclosure, the height H is at least 50%, in particular at least 75%, preferably at least 100% of the width (B).

[0135] Fig. 11Figure 11 shows a receiver 11 with a pump chamber 15 into which a pump 17 has been placed, in order to describe a further embodiment.

[0136] The receiver 11 has a plurality of vacuum chambers 19, 19x and a forevacuum chamber 19vv. The latter is equipped with a forevacuum flange 350 to which a forevacuum pump (not shown) can be connected.

[0137] The lowest vacuum chamber 19x is connected via a channel 352 in a base 339b of a lower part 339 to an intermediate inlet 35y, which leads into a collecting chamber 400 between the two Holweck stages 31x.

[0138] The lower section 339 also includes an outlet channel 338a, which is connected to a forevacuum flange 350a of the pump 17. A forevacuum pump (not shown) can also be connected here. It is understood, however, that the outlet channel 338a can also be connected to the forevacuum chamber 19vv via a corresponding interface. This connection can, for example, be located below the connection between the channel 352 and the vacuum chamber 19x.

[0139] A receiver-side opening of the channel 352 is arranged in a side wall 356a, which is formed on a side surface of the base 339b facing the receiver 11. The receiver 11 has a complementary side wall 356b in the area opposite side wall 356a, which has a pump-side opening of the lowest vacuum chamber 19x. The two openings in the inclined surfaces 356a, 356b are sealed against the outside by a sealing ring (not shown). Shape features can be provided on the lower part 339 and on the receiver 11 (in particular on the side walls 356a, 356b) that enable precise and oriented mounting of the pump 17. For example, complementary axial ribs and grooves can be provided in the walls 356a, 356b (an example for the eighth aspect of this disclosure).

[0140] In Fig. 12An embodiment according to the ninth aspect of the present disclosure is shown. It shows a pump 17 in which an outlet channel 338, which leads from the outlet chamber 334 through the lower part 339 - unlike in Fig. 10 The system is shown to have an axial channel section 358a and a channel section 358b inclined relative to the axis of rotation of the rotor 50. The outlet end of channel 358b is not directly connected to a forevacuum chamber 19vv. This connection is indirect, namely via a transfer channel 360 formed in a cover 362. It has an inclined section that connects to channel section 358b and a horizontal section that connects to chamber 19vv.

[0141] The cover 362 covers the lower part 339 of the pump 17 and secures it in the pump chamber 15. The cover 362 can also provide alternative or additional functionalities, such as cooling by means of cooling fins 364.

[0142] The inclined channel section 358b frees up installation space in the lower part 339, which can be used for other purposes. For example, a lubricant reservoir, which is provided in an area near a mechanical rolling bearing of the rotor 50 (not shown), can be dimensioned more generously than before.

[0143] In the example of the Fig. 12 The ninth aspect of the present disclosure is not realized in the lower part 339, but in the lid 262. The advantage associated with this aspect is nevertheless achieved. Reference symbol list

[0144] 11 Recipient 13 Housing 13a Access opening 15 Pump chamber 17 Turbomolecular pump 19, 19x Vacuum chamber 19vv Pre-vacuum chamber 21 Further vacuum chamber 23 Further vacuum chamber 26 Partition 27 Pump inlet 29 Turbomolecular pump system 29a, 29b, 29x Turbomolecular pump stage 31 Holweck pump system 31a, 31b, 31x Holweck pump stage 32 Holweck sleeve 32a Hub 33, 35, 35x, 35y Intermediate inlet 35z Radial opening 39 Housing wall 45 Cover 50 Rotor 51 Shaft 53 Rotation axis 55 Rotor disk 57 Holweck sleeve 59 Hub 61 Holweck stator 69 Wall section 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 or catch bearing 217 Motor stator 219 Intermediate space 221 Wall 223 Labyrinth seal 300 Bore 302 Inlet-side end 304 Inlet-remote end 310a, 310b Rotor disk 312a, 312b Sleeve section 314 Spacer sleeve 320 Static bearing arrangement 322 Rotor-side bearing arrangement 324 Permanent bearing arrangement 326 Ring magnet 330 Stator sleeve 332 Hollow groove 334 Exhaust chamber 336 Sealing ring 338, 338a, 338b Exhaust channel 339 Lower part 339a Central section 339b Base 340 Channel 342 Motor stator 344 Receiving chamber 350, 350a Forevacuum flange 352 Channel 356a, 356b Side wall 358a Axial channel section 358b Inclined channel section 360 Transfer channel 362 Cover 364 Cooling fins 400 Collection room A, A1, A2 axial extent D, D1 diameter B width of the collection chamber H height of the collection chamber GS1, GS2 gas flow

Claims

1. Rotor (50) for a turbomolecular pump with at least one turbomolecular pumping stage (29x), comprising a rotatably mounted shaft (51) having a bore (300) arranged coaxially with an axis of rotation (53) of the shaft (51), wherein the bore (300) has an axial extent (A1) which is more than 40%, in particular more than 45%, preferably more than 50% of an axial extent (A) of the shaft (51), and which has a diameter which, in a section extending over more than 70%, in particular more than 80%, preferably more than 90% of the axial extent of the bore, is more than 50%, in particular more than 65%, preferably more than 80% of the diameter of the shaft.

2. Rotor (50) according to claim 1, wherein the bore (300) extends from an end (302) of the rotor (51) facing an inlet (27) of the turbomolecular pump into its interior.

3. Rotor (50) according to claim 1 or 2, wherein the axial extent of the bore (300) is more than 50%, in particular more than 60%, preferably more than 70% of an axial extent (A2) of a section of the shaft (51) which carries the at least one turbomolecular pump stage (29x), in particular wherein the shaft (51) carries at least 2, in particular at least 3, preferably at least 4 turbomolecular pump stages (29x) in the region of the axial extent (A1) of the bore (300).

4. Rotor (50) for a turbomolecular pump with at least two turbomolecular pumping stages (29x), in particular according to one of claims 1 to 3, wherein the rotor (50) comprises a rotatably mounted shaft (51) which carries at least two groups of rotor disks (310a, 310b) which each form a rotor-side part of one of the turbomolecular pumping stages (29x), wherein the groups are identical.

5. Rotor according to claim 4, wherein a group comprises at least two components, one of the components forming two rotor disks (310b), in particular wherein the two rotor disks (310b) are connected to each other by a sleeve section.

6. Rotor according to claim 5, wherein at least one of the components is designed in one piece, in particular wherein the components are manufactured by a machining process.

7. Turbomolecular pump with at least one turbomolecular pumping stage (29x), in particular a split flow pump, comprising a rotor, in particular a rotor according to one of claims 1 to 6, which is rotatably mounted by means of a permanent bearing arrangement (324) during operation of the turbomolecular pump relative to spatially fixed components (203) of the turbomolecular pump, wherein the permanent bearing arrangement (324) has at least one rotor-side bearing arrangement (322) and a static bearing arrangement (320) and wherein an axial extent of the rotor-side bearing arrangement (322) is greater than that of the static bearing arrangement (320).

8. Turbomolecular pump, in particular according to claim 7, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) effective in a pumping direction from the pump inlet (27) to the pump outlet, comprising at least a first Holweck pumping stage (31x) and a second Holweck pumping stage (31x) following in the pumping direction, which are in particular arranged radially one inside the other, at least a first intermediate inlet (35x) arranged in the pumping direction upstream or in the region of the first Holweck pumping stage (31x), and at least a second intermediate inlet (35y) located between the first and the second Holweck pumping stage (31x).

9. Turbomolecular pump, in particular according to claim 7 or 8, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) effective in a pumping direction from the pump inlet (27) to the pump outlet, comprising at least a first Holweck pumping stage (31x) and a second Holweck pumping stage (31x) following in the pumping direction, which are in particular arranged radially one inside the other, and at least an intermediate inlet (35y) located between the first and the second Holweck pumping stage (31x), wherein the intermediate inlet (35y) comprises a radial opening (35z) in a wall section extending in an axial direction, which adjoins a pump-active section of a Holweck stator (330) of the first Holweck pumping stage (31).

10. Turbomolecular pump according to claim 9, wherein the Holweck stator comprises a sleeve having both the wall section and the pump-active section.

11. Turbomolecular pump according to claim 9 or 10, wherein a sealing arrangement (336) for sealing the turbomolecular pump on the outlet side against the atmosphere is arranged below the radial opening (35z) in the axial direction from the pump inlet (27).

12. Turbomolecular pump, in particular according to at least one of claims 7 to 11, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) acting in a pumping direction from the pump inlet (27) to the pump outlet, comprising at least a first Holweck pump stage (31x) and a second Holweck pump stage (31x) following in the pumping direction, which are in particular arranged radially one inside the other, and at least one intermediate inlet (35y) located between the first and the second Holweck pump stage (31x), wherein an outlet-side end of the first Holweck pump stage (31x), an inlet-side end of the second Holweck pump stage (31x) and - if present - the radial opening (35z) of the intermediate inlet (35y) open into an annular collecting chamber (400), the axial extent (H) of which is at least 50%, in particular at least 75%, preferably at least 100% of its width. (B) is.

13. Turbomolecular pump, in particular according to at least one of claims 7 to 12, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) acting in a pumping direction from the pump inlet (27) to the pump outlet and a lower part (339) with a receiving space (344) which receives a motor stator (342) of a drive motor for driving the pumping system (29x, 31x), wherein the lower part (339) has at least one channel (340) which is connected to an outlet-side end (334) of the pumping system (29x, 31x) and to a section of the receiving space (344) which is bounded in the axial direction by the motor stator (342) and which faces away from the outlet-side end (334) of the pumping system (29x, 31x).

14. Turbomolecular pump, in particular according to at least one of claims 7 to 13, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) acting in a pumping direction from the pump inlet (27) to the pump outlet, comprising at least a first Holweck pumping stage (31x) and a second Holweck pumping stage (31x) following in the pumping direction, which are in particular arranged radially one inside the other, and at least one intermediate inlet (35y) located between the first and the second Holweck pumping stage (31x), wherein a closing element (339, 362) is provided which covers the turbomolecular pump at least partially in an axial direction in an assembled state and which comprises at least one channel (352) for establishing a connection between the intermediate inlet (35y) and a vacuum chamber (19x) of a recipient (11), wherein the closing element (339, 362) has a first shape feature (356a) exhibitswhich can be brought into interaction with a second form feature (356b), which is complementary to the first form feature (356a) and which is provided for the recipient (11).

15. Turbomolecular pump, in particular according to at least one of claims 7 to 14, comprising: a pump inlet (27), a pump outlet, a pumping system (29x, 31x) acting in a pumping direction from the pump inlet (27) to the pump outlet and a lower part (339) which accommodates a motor stator (342) of a drive motor for driving the pumping system (29x, 31x) and which has at least one outlet channel (338b) which is connected to an outlet-side end (334) of the pumping system (29x, 31x) and the pump outlet, wherein the outlet channel (338b) has an axially extending channel section (358a) and an inclined channel section (358B) which extends obliquely to the axial direction.

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