Vacuum pump having an optimized Holweck pump stage for compensating output losses due to temperature

Abstract

To provide solution means for a problem that a pumping output of a vacuum pump having a Holweck pump stage is lowered on the basis of a deformation depending on a temperature of a Holweck stator or a Holweck stator sleeve, in the vacuum pump.SOLUTION: In a cold state of a vacuum pump 111, a female screw thread 18 has a nominal inside diameter dni which is smaller than a nominal inside diameter of a fixed end part 24 of a Holweck stator sleeve at a free end 22 of the Holweck stator sleeve 169, and also in the cold state of the vacuum pump, a male screw thread 20 has a nominal outside diameter dna which is smaller than a nominal outside diameter of the fixed end part of the Holweck stator sleeve at a free end of the Holweck stator sleeve.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vacuum pump, in particular a turbomolecular vacuum pump, also referred to herein simply as pump, according to the preamble of claim 1, which comprises at least one Holbeck pump stage having a Holbeck rotor and a Holbeck stator, the Holbeck rotor having a rotor shaft provided with a hub and at least one Holbeck rotor sleeve provided on the hub, the Holbeck rotor sleeve concentrically surrounding the rotor shaft, the Holbeck stator having a Holbeck stator sleeve arranged concentrically with respect to the Holbeck rotor sleeve, the Holbeck stator sleeve having a fixed end attached to a fixed housing part of the vacuum pump, a free end axially opposite to the fixed end, an inner surface provided with an internal thread and an outer surface provided with an external thread. [Background technology]

[0002] Vacuum pumps are used in various technical fields. Depending on the requirements, the vacuum pump has one or several pump stages. Generally, the Holweck pump stage is included in a type of molecular vacuum pump and generates a molecular flow by rotating a Holweck rotor relative to a fixed Holweck stator, which heats the vacuum pump during operation. In principle, the vacuum pump may have one or several Holweck stages, in which case several Holweck stages can be operated in series or in parallel with each other. Typically, the Holweck stage is used in turbomolecular vacuum pumps and is followed in the flow direction by one or several turbomolecular pump stages.

[0003] The Holbeck stage has a Holbeck rotor and a Holbeck stator. In this case, the Holbeck rotor has a rotor shaft, and one or more Holbeck rotor sleeves are concentrically attached to the rotor shaft, for example, by a disk-shaped Holbeck hub. The Holbeck stator has one or multiple Holbeck threads. The gas molecules to be pumped are pumped from the intake port to the exhaust port of each Holbeck pump stage along the thread by rotating the Holbeck rotor relative to the Holbeck stator. The thread has a helically winding Holbeck groove defined by the web wall, and in the Holbeck groove, the gas molecules are pumped when the rotor sleeve rotates relative to the stator sleeve. In order to minimize backflow loss, the width of the radial Holbeck gap between the web tip or thread tip and the rotor sleeve should be kept as small as possible.

[0004] Furthermore, a so-called "folded" Holbeck unit is known, in which a plurality of Holbeck stages are concentrically incorporated inside and outside each other. Therefore, the pumping directions of the Holbeck stages that are directly continuous in the radial direction are opposite to each other. Thus, two consecutive Holbeck stages in the flow direction, that is, the outer Holbeck stage (in the radial direction) and the inner Holbeck stage (in the radial direction), may have a common Holbeck stator with Holbeck threads on both sides, which is located between the two rotor sleeves.

[0005] In this case, the Holbeck stator has a fixed end attached to the housing part of the fixed position of the vacuum pump, for example, by press fitting, a free end located axially opposite to the fixed end near the rotor hub, an inner surface formed with female threads, and an outer surface formed with male threads. Based on the small cross-sectional area of the Holbeck stator, a relatively high temperature difference is required in the Holbeck stator to release the introduced heat quantity. This results in a temperature profile with the highest temperature at the free end.

[0006] As a result of heating the Holbeck status sleeve, the Holbeck status sleeve gradually expands radially more and more towards its free end, so that the Holbeck status sleeve gradually deviates greatly from its target width or nominal width from the fixed end towards the free end of the Holbeck status sleeve. Furthermore, as a result, the exhaust speed of the vacuum pump and thus the pump output decrease in an undesirable manner during pump operation.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, the problem underlying the present invention is to provide a solution to the above-mentioned problem that the pumping output of a vacuum pump having a Holbeck pump stage decreases based on deformation depending on the temperature of the Holbeck stator or the Holbeck status sleeve. In other words, the present invention should take into account that the exhaust speed of the vacuum pump set therefor is achieved even under operating conditions at a relatively high temperature.

Means for Solving the Problems

[0008] This problem is solved by a vacuum pump having the features of claim 1, in particular in the cold state of the vacuum pump at room temperature, where the female thread has a nominal inner diameter at the free end of the Holbeck status sleeve that is smaller than the nominal inner diameter at the fixed end of the Holbeck status sleeve, and correspondingly, the male thread also has a nominal outer diameter at the free end of the Holbeck status sleeve that is smaller than the nominal outer diameter at the fixed end of the Holbeck status sleeve in the cold state of the vacuum pump at room temperature.

[0009] In the context of the present invention, when the cold state of the vacuum pump is mentioned, this is understood as the temperature of the vacuum pump in an operating state that is continuously switched off at room temperature in the range of about 20 °C. In other words, in short, the vacuum pump and in particular the Holvex status sleeve have a temperature in the range of about 20 degrees in the cold state. In contrast, in the context of the present invention, when the hot stable state or thermal steady state during operation of the vacuum pump is mentioned, this state represents the temperature of the vacuum pump that is achieved when the vacuum pump is continuously operated at its rated rotational speed.

[0010] In the configuration according to the present invention, the Holvex status sleeve has, at its free end, a nominal inner diameter or outer diameter measured between the web tips or thread tips of female or male threads, respectively. Thus, based on the fact that the Holvex status sleeve has, at its free end, an inner circumference and an outer circumference that are smaller than the inner and outer circumferences at its fixed end, the Holvex status sleeve can thereby expand radially at its free end during operation, depending on the temperature, until the inner and / or outer Holvex clearances have the desired form.

[0011] Therefore, according to the present invention, the Holvex status sleeve has a configuration that deviates from the target form of the Holvex status sleeve in the cold state in order to obtain the desired Holvex clearance. Thus, during operation, the Holvex status sleeve can deform depending on the temperature such that the desired Holvex clearance occurs in the hot state during operation of the vacuum pump.

[0012] Hereinafter, the preferred embodiments of the present invention will be described. Further embodiments can be clarified from the dependent claims, the description of the drawings, and the drawings themselves.

[0013] According to one form, it can be assumed that the hub is attached to the rotor shaft and the Horvbeck rotor sleeve is attached to the hub. Thus, the hub and the rotor shaft are separately handleable parts, and these parts are detachably or non-detachably coupled to each other during the assembly of the vacuum pump. Similarly, in this form, the hub and the Horvbeck rotor sleeve are separately handleable parts, and these parts can be detachably or non-detachably coupled to each other during the assembly of the vacuum pump.

[0014] Alternatively to the above-described form, it can be assumed that the hub is integrally formed with the rotor shaft, while on the other hand, the Horvbeck rotor sleeve is attached to the hub, or the Horvbeck rotor sleeve is integrally formed with the hub and the hub is attached to the rotor shaft.

[0015] The Holweck stator is configured as two-sided Holweck stators having a Holweck stator sleeve with internal and external threads, so that the Holweck rotor consequently has an inner Holweck rotor sleeve and an outer Holweck rotor sleeve, both of which concentrically surround the rotor shaft. In this case, the outer Holweck rotor sleeve concentrically surrounds the Holweck stator sleeve, and the Holweck stator sleeve concentrically surrounds the inner Holweck rotor sleeve. Thus, the inner Holweck rotor sleeve forms an inner Holweck pump stage together with the internal threads of the Holweck stator sleeve, while the outer Holweck stator sleeve forms an outer Holweck pump stage together with the external threads of the Holweck rotor sleeve. In this case, according to one aspect of the invention, it can be assumed that, in the cold state, the configuration of both the inner Holweck pump stage and the outer Holweck pump stage deviates from the desired configuration of the respective Holweck clearances. However, based on the fact that the Holweck stator sleeve has a nominal inner diameter and a nominal outer diameter at its free end that are smaller than the nominal inner diameter and the nominal outer diameter at its fixed end, during operation of the vacuum pump, at its free end, it can expand radially according to the temperature, so that both the inner Holweck pump stage and the outer Holweck pump stage have a Holweck clearance that at least approximates the desired configuration in the thermally steady state.

[0016] Indeed, the inner diameter of the internal threads of the Holweck stator sleeve can decrease stepwise towards its free end, but according to a preferred embodiment, it can be assumed that in the cold state of the vacuum pump, the nominal inner diameter of the internal threads of the Holweck stator sleeve decreases continuously or gradually towards its free end. For example, the nominal inner diameter of the internal threads can decrease according to a function having a linear or concave curve as it approaches the free end of the Holweck stator sleeve.

[0017] In a suitable form, in the cold state of the vacuum pump, the nominal outer diameter of the male thread of the Holvex status sleeve can decrease stepwise or gradually towards its free end. In this case, in the latter case, the nominal outer diameter can decrease according to a function having a linear or convex curve as it approaches the free end of the Holvex status sleeve. In any case, the nominal inner diameter or the nominal outer diameter decreases gradually or monotonically towards the free end of the Holvex status sleeve, which means that the Holvex status sleeve has the smallest nominal inner diameter and nominal outer diameter at its free end. This is due to the fact that the Holvex stator has the highest temperature at its free end due to operation, and thus the largest expansion due to heat occurs there. Therefore, the Holvex status sleeve has both the smallest nominal inner diameter and the smallest nominal outer diameter at its free end, thereby being able to compensate to some extent for the deformation caused by the temperature of the Holvex stator.

[0018] According to yet another form, in the cold state of the vacuum pump, the nominal outer diameter of the male thread of the Holvex status sleeve decreases as follows towards the free end of the Holvex status sleeve, i.e., in a stable hot state during operation of the vacuum pump or in a thermal steady state, a radial Holvex gap having an essentially constant width between the Holvex rotor sleeve and the male thread, especially the thread tip of the male thread, is created between the fixed end and the free end of the Holvex status sleeve. Additionally or alternatively, according to another form, in the cold state of the vacuum pump, the nominal inner diameter of the female thread of the Holvex status sleeve decreases as follows towards the free end of the Holvex status sleeve, i.e., in a stable hot state during operation of the vacuum pump or in a thermal steady state, a radial Holvex gap having an essentially constant width between the Holvex rotor sleeve and the female thread, especially the thread tip of the female thread, is created between the fixed end and the free end of the Holvex status sleeve.

[0019] In order to be able to form a Hollbeck gap of a constant size in the thermal steady state, in the cold state of the vacuum pump, both the nominal inner diameter and the nominal outer diameter of the female or male thread of the Hollbeck stator sleeve gradually decrease towards the free end of the Hollbeck stator sleeve in the manner already described above. It has thus been found advantageous. Therefore, in short, the temperature of the Hollbeck stator sleeve gradually increases towards its free end during operation as well, and in this case, the Hollbeck stator sleeve has the highest temperature at its free end. Thus, the decrease in the nominal inner and outer diameters towards the free end of the Hollbeck stator sleeve follows to some extent the temperature profile of the Hollbeck stator sleeve towards its free end, whereby the expansion due to the temperature of the Hollbeck stator sleeve can accurately compensate so that the Hollbeck gaps of both the inner Hollbeck pump stage and the outer Hollbeck pump stage have essentially a constant size in the hot and stable state during operation.

[0020] According to yet another embodiment, the female thread of the Hollbeck stator sleeve has a constant thread depth between its fixed end and its free end in the cold state of the vacuum pump, and the inner surface of the Hollbeck stator sleeve that forms the groove bottom of the female thread is assumed to define a decreasing valley diameter of the female thread towards the free end of the Hollbeck stator sleeve in the cold state of the vacuum pump. In addition or alternatively to this, according to another embodiment, the male thread of the Hollbeck stator sleeve has a constant thread depth between its fixed end and its free end in the cold state of the vacuum pump, and the outer surface of the Hollbeck stator sleeve that forms the groove bottom of the female thread is assumed to define a decreasing valley diameter of the male thread towards the free end of the Hollbeck stator sleeve in the cold state of the vacuum pump.

[0021] When the thread depths of both the female thread and the male thread are constant and the root diameter of the female thread and the root diameter of the male thread decrease towards the free end of the Holvex status sleeve, according to another form, in the cold state of the vacuum pump, when the root diameter of the female thread and the root diameter of the male thread decrease at the same strength or at the same ratio towards the free end of the Holvex status sleeve, the Holvex status sleeve can be assumed to have a constant wall thickness between the fixed end and the free end of the Holvex status sleeve.

[0022] However, different from the above-mentioned form, it is not essential that the root diameter of the female thread and the root diameter of the male thread decrease to the same extent towards the free end of the Holvex status sleeve. Rather, according to another form, the Holvex status sleeve has a wall thickness that decreases, for example, gradually or step by step, towards the free end of the Holvex status sleeve. In this case, the male thread root diameter decreases more strongly than the female thread root diameter towards the free end of the Holvex status sleeve, or the male thread root diameter decreases more strongly than the female thread root diameter towards the free end of the Holvex status sleeve.

[0023] Alternatively to the above-mentioned form having female threads and / or male threads of a certain depth, according to another form, the inner surface of the Holvex status sleeve defines a constant root diameter of the female thread between the fixed end and the free end of the Holvex status sleeve in the cold state of the vacuum pump. In this case, the female thread has a thread depth that increases towards the free end of the Holvex status sleeve, which means that the inner diameter of the female thread decreases in a desired form towards the free end of the Holvex status sleeve, and this can be assumed. Additionally or alternatively, according to another form, the outer surface of the Holvex status sleeve defines a constant root diameter of the male thread between the fixed end and the free end of the Holvex status sleeve in the cold state of the vacuum pump. In this case, since the male thread has a thread depth that decreases towards the free end of the Holvex status sleeve, the root diameter of the male thread can be assumed to decrease in a desired form towards the free end of the Holvex status sleeve.

[0024] Hereinafter, the present invention will be described by way of example with reference to the drawings.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0026] The turbo molecular pump 111 shown in Fig. 1 has a pump intake port 115 surrounded by an intake flange 113. As is known per se, a recipient (not shown) may be connected to the pump intake port 115. The gas arriving from the recipient can be sucked in from the recipient through the pump intake port 115 and pumped through the pump to the pump exhaust port 117. An auxiliary vacuum pump, such as a rotary vane pump, for example, may be connected to the pump exhaust port 117.

[0027] The intake flange 113 forms the upper end part of the housing 119 of the vacuum pump 111 in the orientation of the vacuum pump according to Fig. 1. The housing 119 has a lower part 121. A lateral electronics housing 123 is arranged in the lower part 121. The electrical and / or electronic components of the vacuum pump 111 for operating, for example, an electric motor 125 (see also Fig. 3) arranged in the vacuum pump are accommodated in the electronics housing 123. The electronics housing 123 is provided with a plurality of connection parts 127 for accessories. Furthermore, a data interface 129 (for example, compliant with the RS485 standard) and a current supply connection part 131 are arranged in the electronics housing 123.

[0028] There are also turbo molecular pumps that are connected to external drive electronics without having this type of attached electronics housing.

[0029] The housing 119 of the turbo molecular pump 111 is provided with an intake port 133 for ventilation, particularly in the form of a ventilation valve. Through the intake port 133 for ventilation, the vacuum pump 111 can be ventilated. In the region of the lower part 121, further above it, a seal gas connection part 135 (also referred to as a purge gas connection part) is arranged. Through the seal gas connection part 135, purge gas can be sent into the motor chamber 137 to protect the electric motor 125 (see, for example, FIG. 3) against the gas pumped by the pump. Inside the motor chamber 137, the electric motor 125 is accommodated in the vacuum pump 111. In the lower part 121, further above it, two coolant connection parts 139 are arranged. In this case, one coolant connection part is provided as an intake port for the coolant, and the other coolant connection part is provided as an exhaust port. The coolant can be introduced into the vacuum pump for cooling purposes. Another turbo molecular vacuum pump (not shown) that exists is operated exclusively in an air-cooled manner.

[0030] Since the lower surface 141 of the vacuum pump can be used as a base, the vacuum pump 111 can be operated vertically with respect to the lower surface 141. Moreover, the vacuum pump 111 can be fixed to the recipient via the intake flange 113, and thus can be operated in a so-called suspended state. Furthermore, the vacuum pump 111 may be configured to be operable even when it is oriented in a direction different from that shown in FIG. 1. It is also possible to realize a form of the vacuum pump in which the lower surface 141 is not arranged downward, but horizontally or upward. In this case, in principle, any angle is conceivable.

[0031] Another existing turbo molecular vacuum pump (not shown) that is larger than the particularly illustrated pump cannot be operated vertically.

[0032] On the lower surface 141 shown in FIG. 2, various screws 143 are further arranged. By these screws 143, the constituent members of the vacuum pump, which are not specifically specified here, are fixed to each other. For example, the bearing cover 145 is fixed to the lower surface 141.

[0033] At 141 below, a fixing hole 147 is further arranged. Through the fixing hole 147, the pump 111 can be fixed to, for example, the installation surface. This is impossible in the case of another existing turbo molecular vacuum pump (not shown) that is larger than the specifically illustrated pump.

[0034] From FIG. 2 to FIG. 5, a coolant pipeline 148 is shown. Inside the coolant pipeline 148, the coolant introduced and led out through the coolant connection part 139 can circulate.

[0035] As shown in the cross-sectional views from FIG. 3 to FIG. 5, the vacuum pump has a plurality of process gas pump stages. The process gas pump stages are for pumping the process gas acting on the pump intake port 115 to the pump exhaust port 117.

[0036] Inside the housing 119, a rotor 149 is arranged. The rotor 149 has a rotor shaft 153 that can rotate about the rotation axis 151.

[0037] The turbo molecular pump 111 has a plurality of turbo molecular pump stages connected in series with each other so as to exert a pumping action. The turbo molecular pump stages have a plurality of radial moving blades 155 fixed to the rotor shaft 153, and a plurality of stationary blades 157 arranged between the moving blades 155 and fixed inside the housing 119. In this case, one moving blade 155 and one adjacent stationary blade 157 form one turbo molecular pump stage respectively. The stationary blades 157 are held at a desired axial interval from each other by a spacer ring 159.

[0038] The vacuum pump further has Holweck pump stages arranged inside and outside each other in the radial direction and connected in series with each other so as to exert a pumping action. There is another turbo molecular vacuum pump (not shown) that does not have Holweck pump stages.

[0039] The rotor of the Holweck pump stage has a rotor hub 161 disposed on the rotor shaft 153, and two cylindrical side surface-like Holweck rotor sleeves 163, 165 fixed to the rotor hub 161 and supported by this rotor hub 161. The Holweck rotor sleeves 163, 165 are oriented coaxially with respect to the rotation axis 151 and are incorporated inside and outside each other in the radial direction. Two cylindrical side surface-like Holweck stator sleeves 167, 169 are further provided. The Holweck stator sleeves 167, 169 are likewise oriented coaxially with respect to the rotation axis 151 and are incorporated inside and outside each other when viewed in the radial direction.

[0040] The pumping surface of the Holweck pump stage is formed by the side surfaces, that is, by the inner and / or outer side surfaces in the radial direction of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The inner side surface in the radial direction of the outer Holweck stator sleeve 167 faces the outer side surface in the radial direction of the outer Holweck rotor sleeve 163 while forming a radial Holweck gap 171, and together with this outer side surface, forms the first Holweck pump stage following the turbomolecular pump. The inner side surface in the radial direction of the outer Holweck rotor sleeve 163 faces the outer side surface in the radial direction of the inner Holweck stator sleeve 169 while forming a radial Holweck gap 173, and together with this outer side surface, forms the second Holweck pump stage. The inner side surface in the radial direction of the inner Holweck stator sleeve 169 faces the outer side surface in the radial direction of the inner Holweck rotor sleeve 165 while forming a radial Holweck gap 175, and together with this outer side surface, forms the third Holweck pump stage.

[0041] A radially extending channel may be provided at the lower end of the Holbeck lotus sleeve 163. Through the channel, the Holbeck gap 171 located radially outside is connected to the central Holbeck gap 173. A radially extending channel may further be provided at the upper end of the inner Holbeck stator sleeve 169. Through the channel, the central Holbeck gap 173 is connected to the Holbeck gap 175 located radially inside. Thereby, a plurality of Holbeck pump stages incorporated inside and outside each other are connected in series with each other. A connection channel 179 leading to the exhaust port 117 may further be provided at the lower end of the Holbeck rotor sleeve 165 located radially inside.

[0042] The surfaces of the Holbeck stator sleeves 167 and 169 that exhibit the aforementioned pumping action each have a plurality of Holbeck grooves that extend axially while spiraling around the rotation axis 151. On the other hand, the opposing side surfaces of the Holbeck rotor sleeves 163 and 165 are formed smoothly and send the gas for the operation of the vacuum pump 111 forward in the Holbeck grooves.

[0043] For the rotatable shaft support of the rotor shaft 153, a rolling bearing 181 is provided in the region of the pump exhaust port 117, and a permanent magnet type magnetic bearing 183 is provided in the region of the pump intake port 115.

[0044] In the region of the rolling bearing 181, a conical splash nut 185 is provided on the rotor shaft 153. The splash nut 185 has an outer diameter that increases toward the rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping member of the working medium storage portion. In another existing turbo molecular vacuum pump (not shown), a splash screw may be provided instead of the splash nut. Thereby, various configurations are achievable, and in the above relationship, the term "splash tip" is also used.

[0045] The actuating medium storage section has a plurality of absorbent disks 187 stacked one above the other. These disks 187 are impregnated with an actuating medium, for example a lubricant, for the rolling bearing 181.

[0046] During operation of the vacuum pump 111, the actuating medium is transmitted by capillary action from the actuating medium storage section via the scraping-off member to the rotating splash nut 185 and then, based on centrifugal force, along the splash nut 185 towards the increasing outer diameter of the splash nut 185 and towards the rolling bearing 181. There, for example, the lubricating function is fulfilled. The rolling bearing 181 and the actuating medium storage section are surrounded in the vacuum pump by a trough-shaped insert 189 and a bearing cover 145.

[0047] The permanent magnet type magnetic bearing 183 has a bearing half 191 on the rotor side and a bearing half 193 on the stator side. These each have a ring stack, and the ring stack consists of a plurality of rings 195, 197 of permanent magnets stacked vertically in the axial direction. The ring magnets 195, 197 face each other while forming a radial bearing gap 199 therebetween. In this case, the rotor-side ring magnet 195 is arranged on the radially outer side, and the stator-side ring magnet 197 is arranged on the radially inner side. The magnetic field existing within the bearing gap 199 causes a magnetic repulsive force between the ring magnets 195, 197. That repulsive force realizes the radial shaft support of the rotor shaft 153. The rotor-side ring magnet 195 is supported by a support portion 201 of the rotor shaft 153. The support portion 201 surrounds the ring magnet 195 on the radially outer side. The stator-side ring magnet 197 is supported by a stator-side support portion 203. The support portion 203 extends through the ring magnet 197 and is suspended by a radial support member 205 of the housing 119. Parallel to the rotation axis 151, the rotor-side ring magnet 195 is fixed by a cover element 207 connected to the support portion 203. The stator-side ring magnet 197 is fixed in one direction parallel to the rotation axis 151 by a fixed ring 209 connected to the support portion 203 and a fixed ring 211 connected to the support portion 203. A disc spring 213 may be further provided between the fixed ring 211 and the ring magnet 197.

[0048] An emergency bearing or a safety bearing 215 is provided inside the magnetic bearing. The emergency bearing or the safety bearing 215 rotates idly in a non-contact manner during the normal operation of the vacuum pump, and only engages when the rotor 149 is excessively displaced radially relative to the stator. Thus, a radial stopper for the rotor 149 is formed to prevent a collision between the structure on the rotor side and the structure on the stator side. The safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial gap together with the rotor 149 and / or the stator. Due to the gap, the safety bearing 215 does not engage during normal pump operation. When the safety bearing 215 engages during a radial displacement, and the radial displacement is dimensioned large enough, the safety bearing 215 does not engage during the normal operation of the vacuum pump and is simultaneously small enough to prevent a collision between the structure on the rotor side and the structure on the stator side in any situation.

[0049] The vacuum pump 111 has an electric motor 125 that rotationally drives the rotor 149. The armature of the electric motor 125 is formed by the rotor 149. The rotor shaft 153 of the rotor 149 extends through the motor stator 217. A permanent magnet assembly may be disposed radially outward or embedded in the portion of the rotor shaft 153 that extends through the motor stator 217. An intermediate chamber 219 is disposed between the motor stator 217 and the portion of the rotor 149 that extends through the motor stator 217. The intermediate 219 has a radial motor gap. Through the motor gap, the motor stator 217 and the permanent magnet assembly may magnetically influence each other to transmit a driving torque.

[0050] The motor stator 217 is fixed within the housing in a motor chamber 137 provided for the electric motor 125. Through a seal gas connection 135, seal gas (also referred to as purge gas, which may be, for example, air or nitrogen) can reach the motor chamber 137. Through the seal gas, the electric motor 125 can be protected against the process gas, for example, the corrosive part of the process gas. The motor chamber 137 may be evacuated via the pump exhaust port 117. That is, within the motor chamber 137, at least approximately, a vacuum pressure realized by an auxiliary vacuum pump connected to the pump exhaust port 117 acts.

[0051] Between the rotor hub 161 and the wall portion 221 defining the motor chamber 137, a so-called labyrinth seal 223 known per se may be further provided. Thereby, in particular, a better seal of the motor chamber 217 against the Horvbeck pump stage located radially outward is achieved.

[0052] Hereinafter, with reference to FIGS. 6 to 8, various embodiments of the Horvbeck pump stage 10 configured according to the present invention will be described. The Horvbeck pump stage according to the present invention can be assembled in place of the aforementioned Horvbeck pump stage in the case of a turbomolecular vacuum pump 111. Moreover, in that case, the other structure of the turbomolecular vacuum pump 111 and the basic structure of the Horvbeck pump stage having three pump stages incorporated inside and outside, which is also collectively referred to as a single "Horvbeck pump stage" hereinafter, may be maintained.

[0053] As can be seen from FIG. 6, the Holbeck pump stage 10 illustrated therein has essentially the same structure as the Holbeck pump stage of the vacuum pump 111 described with reference to FIGS. 1 to 5. In particular, this Holbeck pump stage 10 also has a rotor hub 161 disposed on the rotor shaft 153, and two cylindrical side surface-shaped rotor sleeves 163, 165 attached to and supported by the rotor hub 161. The rotor sleeves 163, 165 are coaxially oriented with respect to the axis of rotation 151 and are incorporated inside and outside in the radial direction. Further, two cylindrical side surface-shaped Holbeck stator sleeves 167, 169 are provided, and the Holbeck stator sleeves 167, 169 are also coaxially oriented with respect to the axis of rotation 151 and are incorporated inside and outside as seen in the radial direction.

[0054] Accordingly, in accordance with the above description, the outer Holbeck stator sleeve 167, together with the outer Holbeck rotor sleeve 163, forms the first or outer Holbeck pump stage. The outer Holbeck rotor sleeve 163, together with the inner Holbeck stator sleeve 169, forms the second or central Holbeck pump stage. Similarly, the inner Holbeck stator sleeve 169, together with the inner Holbeck rotor sleeve 165, forms the third or inner Holbeck pump stage. In this regard, the illustrated structure is consistent with the structure described above with reference to FIGS. 3 to 5.

[0055] Similarly, the Holbeck status sleeves 167, 169 of FIG. 6 have a plurality of Holbeck grooves that extend axially in a spiral around the axis of rotation 151. In the illustrated inner Holbeck status sleeve 169, these grooves are formed by webs 16 formed on both the inner surface 12 and the outer surface 14 of the status sleeve 169. The webs 16 extend spirally around the axis of rotation 151 and are shown here only very schematically. Thus, the leading edges of the webs 16 form the nominal inner diameter or the nominal outer diameter of each thread, while the inner surface 12 or the outer surface 14 corresponds to the female thread valley diameter dki or the male thread valley diameter dka of each thread 18, 20. Since each Holbeck gap is related to the distance between the leading edge of the web 16 and the surface of the rotor sleeves 163, 165 that exerts a pumping action, an envelope line surrounding the web leading edge or the thread leading edge is entered here, and the symbol "26" is assigned to this.

[0056] Furthermore, as can be seen from FIG. 6, in the illustrated Holbeck pump stage 10, according to the present invention here, in the cold state of a vacuum pump at room temperature of about 20 °C, it can be assumed that the female thread 18 has a nominal inner diameter dni that is smaller than the nominal inner diameter at the fixed end 24 of the Holbeck status sleeve 169 at the free end 22 of the Holbeck status sleeve 169. Similarly, the male thread 20 also has a nominal outer diameter dna that is smaller than the nominal outer diameter at the fixed end 24 of the Holbeck status sleeve 169 at the free end 22 in the cold state. At the fixed end 24, the Holbeck status sleeve 169 is attached to the housing part at a fixed position of the vacuum pump 111.

[0057] In the embodiment shown with respect to FIG. 6, in particular, the inner surface 12 and the outer surface 14 of the status sleeve 169 having the female thread 18 and the male thread 20 are assumed to have a conical structure and to be tapered gradually towards the free end 22 of the Holvex status sleeve 169 in particular. In contrast, the thread depth or the radial dimension of the web 16 of the female thread 18 or the male thread 20 is constant between the fixed end 24 and the free end 22 of the status sleeve 169. Similarly, in this embodiment, the Holvex status sleeve 169 has a wall thickness that is constant between the fixed end 24 and the free end 22 of the Holvex status sleeve 169.

[0058] However, alternatively to this, it can be assumed that the Holvex status sleeve 169 has a wall thickness that decreases towards the free end 22 of the Holvex status sleeve 169. However, in this case, additionally, the thread height of the female thread 18 increases towards the free end 22 and / or the thread height of the male thread 20 decreases towards the free end 22, whereby it can be assumed that at the free end 22 of the Holvex status sleeve 169, the female thread and the male thread have a nominal inner diameter or nominal outer diameter dni, dna that is smaller than the nominal inner diameter or nominal outer diameter of the fixed end 24 of the Holvex status sleeve 169.

[0059] Therefore, based on the tapered configuration inside and outside the Holbeck status sleeve 169 or the envelope 26 of the Holbeck status sleeve 169, the Holbeck status sleeve 169 can expand radially according to the temperature during the operation of the vacuum pump 111, as suggested by the dashed line in FIG. 5. Therefore, in the stable hot state during operation of the vacuum pump 111, an inner Holbeck gap 175 having an essentially constant size or width between the fixed end 24 and the free end 22 can be formed between the inner Holbeck rotor sleeve 165 and the Holbeck status sleeves 169 on both sides. Similarly, based on the tapered configuration of the Holbeck status sleeve 169 towards the free end 22, an outer Holbeck gap 173 having an essentially constant size or width between the fixed end 24 and the free end 22 can occur between the Holbeck status sleeve 169 and the outer rotor sleeve 163 in the hot state during operation.

[0060] Referring to FIG. 6, different from the embodiments described above, in the embodiment of FIG. 7, instead of assuming that the Holves status sleeve 169 tapers inwardly and outwardly towards its free end 22, rather in the embodiment of FIG. 7, it is assumed that the Holves status sleeve 169 and in particular the inner surface 12 and the outer surface 14 of the Holves sleeve 169 have a substantially cylindrical configuration. Nevertheless, at the free end 22 of the status sleeve 169, in order to ensure that the female thread 18 and the male thread 22 have a nominal inner diameter dni or a nominal outer diameter dna that is smaller than the nominal inner diameter or the nominal outer diameter at the fixed end 24, in the embodiment of FIG. 7, the female thread 18 has a thread depth that increases towards the free end 22 of the Holves status sleeve 169, while on the other hand, the male thread 20 has a thread depth that decreases towards the free end 22 of the Holves status sleeve 169. This ensures that, similar to the embodiments described above with reference to FIG. 6, the envelope 26 of the Holves status sleeve 169 tapers inwardly and outwardly towards the free end 22. Therefore, since the status sleeve 169 can expand according to the temperature during the operation of the vacuum pump 111, in the thermal steady state, an inner Holves gap 173 and an outer Holves gap 175, which have an essentially constant size between the fixed end 24 and the free end 22 of the Holves status sleeve 169, can occur.

[0061] In the embodiment shown in FIG. 8, the wall thickness of the holbeck status sleeve 169 is constant, provided that the holbeck status sleeve 169 tapers stepwise towards the free end 22 of the status sleeve 169. In this embodiment, the thread depth of the female thread 18 increases over each individual step towards the free end 22, before decreasing significantly at the transition to the next step, such that the envelope 26 has a nominal inner diameter dni or a nominal outer diameter dna at the free end 22 in the cold state that is smaller than the corresponding diameter at the fixed end 24. In contrast, the thread depth of the male thread decreases towards the free end 22 in the region of each step, before increasing significantly at the transition to the next step, such that overall, the nominal outer diameter dna decreases in the desired shape towards the free end 22.

[0062] Without going into detail about this, the embodiments according to FIGS. 6, 7 and 8 may be combined with each other, in which case additionally, it may be assumed that the wall thickness of the holbeck status sleeve 169 is not constant without departing from the concept according to the invention. Thus, at the free end 22 of the status sleeve 169, the nominal inner and outer diameters of the female and male threads are smaller than the nominal inner and outer diameters at the fixed end 24, and for this purpose, the thread depths of the female thread 18 and the male thread 20 may vary in the axial direction of the status sleeve 169, whereby the envelope 26 is considered to taper conically towards the free end 22 on both the inner and outer sides, regardless of the configuration of the inner surface 12 and the outer surface 14.

[0063] In the turbo molecular vacuum pump 111 described above with reference to FIGS. 1 to 5, the hub 161 and the rotor shaft 153 are separately handleable parts that are detachably or non-detachably coupled to each other for the first time during the assembly of the vacuum pump 111. Similarly, in this embodiment, the hub 161 and the holbeck rotor sleeves 163, 165 are separately handleable parts that are detachably or non-detachably coupled to each other for the first time during the assembly of the vacuum pump. Such a design is particularly suitable for use in medium and large turbo molecular vacuum pumps.

[0064] Alternatively, according to the embodiment schematically shown in FIG. 9, it can be assumed that the hub 161 is formed integrally with the rotor shaft 153, and the Holweck rotor sleeves 163, 165 are also formed integrally with the hub 161. Therefore, the Holweck rotor is a single part or an integral part.

[0065] Alternatively, according to the embodiment schematically shown in FIG. 10, only the two Holweck rotor sleeves 163, 165 are formed integrally with the hub 161, while the hub 161 and the rotor shaft 153 are separately handleable parts that are detachably or non-detachably coupled to each other for the first time during the assembly of the vacuum pump.

[0066] Finally, according to the embodiment schematically shown in FIG. 11, only the rotor shaft 153 is formed integrally with the hub 161, while the hub 161 and the Holweck rotor sleeves 163, 165 are separately handleable parts that are detachably or non-detachably coupled to each other for the first time during the assembly of the vacuum pump. This embodiment is particularly suitable for use with smaller turbo molecular vacuum pumps. Although this application relates to the invention described in the claims, it includes the following as other aspects. 1. A vacuum pump (111), particularly a turbomolecular vacuum pump (111), comprising at least one Holweck pump stage (10) having a Holweck rotor and a Holweck stator, the Holweck rotor having a rotor shaft (153) provided with a hub (161) and at least one Holweck rotor sleeve (163, 165) provided on the hub (161), the Holweck rotor sleeve (163, 165) concentrically surrounding the rotor shaft, the Holweck stator having a Holweck stator sleeve (169) arranged concentrically with the Holweck rotor sleeve (163, 165), the Holweck stator sleeve (169) having a fixed end (24) attached to a stationary housing portion of the vacuum pump (111), a free end (22) located axially opposite to the fixed end (24), an inner surface (12) formed with an internal thread (18), and an outer surface (14) formed with an external thread (20), in a vacuum pump, in the cold state of the vacuum pump (111), the internal thread (18) has a nominal inner diameter (dni) smaller than the nominal inner diameter of the fixed end (24) of the Holweck stator sleeve (169) at the free end (22) of the Holweck stator sleeve (169), and the external thread (20) also has a nominal outer diameter (dna) smaller than the nominal outer diameter of the fixed end (24) of the Holweck stator sleeve (169) at the free end (22) of the Holweck stator sleeve (169) in the cold state of the vacuum pump (111), characterized by the vacuum pump (111). 2. The vacuum pump (111) according to item 1 above, characterized in that the nominal inner diameter (dni) of the internal thread (18) of the Holweck stator sleeve (169) gradually or stepwise decreases towards the free end (22) of the Holweck stator sleeve (169). 3. In a thermally stable state during operation of the vacuum pump (111), the nominal inner diameter (dni) of the female thread (18) of the Holbeck stator sleeve (169) decreases towards the free end (22) of the Holbeck stator sleeve (169) so that a Holbeck gap (175) having an essentially constant size, in particular a constant size, is formed between the Holbeck rotor sleeve (165) and the female thread (18) between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169). The vacuum pump (111) according to 1 or 2 above, characterized in that. 4. The female thread (18) has a constant thread depth between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169), and the inner surface (12) of the Holbeck stator sleeve (169) defines the valley diameter (dki) of the female thread (18) that decreases towards the free end (22) of the Holbeck stator sleeve (169) in the cold state of the vacuum pump (111). The vacuum pump (111) according to any one of 1 to 3 above, characterized in that. 5. The inner surface (12) of the Holbeck stator sleeve (169) defines the valley diameter (dki) of the female thread (18) that is constant between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169) in the cold state of the vacuum pump (111), and the female thread (18) has a thread depth that increases towards the free end (22) of the Holbeck stator sleeve (169). The vacuum pump (111) according to any one of 1 to 3 above, characterized in that. 6. The nominal outer diameter (dna) of the male thread (18) of the Holbeck stator sleeve (169) gradually or stepwise decreases towards the free end (22) of the Holbeck stator sleeve (169). The vacuum pump (111) according to any one of 1 to 5 above, characterized in that. 7. In a thermally stable state during the operation of the vacuum pump (111), a radially Holweck gap (173) having an essentially constant size, in particular a constant size, is formed between the Holweck rotor sleeve (163) and the male thread (20) between the fixed end (24) and the free end (22) of the Holweck stator sleeve (169). The nominal outer diameter (dna) of the male thread (20) of the Holweck stator sleeve (169) decreases towards the free end (22) of the Holweck stator sleeve (169). The vacuum pump (111) according to any one of the above 1 to 6 is characterized by this. 8. The male thread (20) has a constant thread depth between the fixed end (24) and the free end (22) of the Holweck stator sleeve (169). The outer surface (14) of the Holweck stator sleeve (169) defines the root diameter (dka) of the male thread (20) which decreases towards the free end (22) of the Holweck stator sleeve (169) in the cold state of the vacuum pump (111). The vacuum pump (111) according to any one of the above 1 to 7 is characterized by this. 9. The outer surface (14) of the Holweck stator sleeve (169) defines the root diameter (dka) of the male thread (20) which is constant between the fixed end (24) and the free end (22) of the Holweck stator sleeve (169) in the cold state of the vacuum pump (111). The male thread (20) has a thread depth that decreases towards the free end (22) of the Holweck stator sleeve (169). The vacuum pump (111) according to any one of the above 1 to 7 is characterized by this. 10. The Holweck stator sleeve (169) has a constant wall thickness between the fixed end (24) and the free end (22) of the Holweck stator sleeve (169), or The Holweck stator sleeve (169) has a wall thickness that gradually or stepwise decreases towards the free end (22) of the Holweck stator sleeve (169) The vacuum pump (111) according to any one of the above 1 to 9 is characterized by this. 11. The Holbeck rotor has inner and outer Holbeck rotor sleeves (163) concentrically surrounding a rotor shaft (153), and the outer Holbeck rotor sleeve (163) concentrically surrounds a Holbeck stator sleeve, and the Holbeck stator sleeve concentrically surrounds the inner Holbeck rotor sleeve (165), and the vacuum pump (111) according to any one of 1 to 10 above is characterized in this. 12. The hub (161) is attached to the rotor shaft (153), and the Holbeck rotor sleeves (163, 165) are attached to the hub (161), and the vacuum pump (111) according to any one of 1 to 11 above is characterized in this. 13. The hub (161) is integrally formed with the rotor shaft (153), and on the other hand, the Holbeck rotor sleeves (163, 165) are attached to the hub (161), or the Holbeck rotor sleeves (163, 165) are integrally formed with the hub (161), and the hub (161) is attached to the rotor shaft (153) and the vacuum pump (111) according to any one of 1 to 11 above is characterized in this.

Description of Symbols

[0067] 10 Holbeck pump stage 12 Inner surface 14 Outer surface 16 Web 18 Female thread 20 Male thread 22 Free end 24 Fixed end 26 Envelope 111 Turbo molecular pump 113 Inlet flange 115 Pump inlet 117 Pump exhaust 119 Housing 121 Lower part 123 Electronics housing 125 Electric motor 127 Accessory connection 129 Data interface 131 Current supply connection 133 Ventilation inlet 135 Seal gas connection part 137 Motor chamber 139 Coolant connection part 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixed hole 148 Coolant pipeline 149 Rotor 151 Axis of rotation 153 Rotor shaft 155 Moving blade 157 Stationary blade 159 Spacer ring 161 Rotor hub 163 Holbeck rotor sleeve 165 Holbeck rotor sleeve 167 Holbeck stator sleeve 169 Holbeck stator sleeve 171 Holbeck gap 173 Holbeck gap 175 Holbeck gap 179 Connection channel 181 Rolling bearing 183 Permanent magnet type magnetic bearing 185 Splash nut 187 Disk 189 Insert 191 Bearing half on the rotor side 193 Bearing half on the stator side 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Support part 203 Support part 205 Radial strut 207 Cover element 209 Support ring 211 Fixed ring 213 Disc spring 215 Emergency bearing or safety bearing 217 Motor stator 219 Intermediate chamber 221 Wall part 223 Labyrinth seal dni Nominal inner diameter dna Nominal outer diameter dki Female thread groove diameter dka Male thread groove diameter

Claims

Claim 1 A vacuum pump (111), comprising: at least one Halbach pump stage (10) having a Halbach rotor and a Halbach stator; the Halbach rotor has a rotor shaft (153) provided with a hub (161) and at least one Halbach rotor sleeve (163, 165) provided on the hub (161), and the Halbach rotor sleeve (163, 165) concentrically surrounds the rotor shaft; the Halbach stator has a Halbach stator sleeve (169) arranged concentrically with the Halbach rotor sleeve (163, 165), and the Halbach stator sleeve (169) has a fixed end (24) attached to a stationary housing portion of the vacuum pump (111), a free end (22) located axially opposite to the fixed end (24), an inner surface (12) formed with a female thread (18), and an outer surface (14) formed with a male thread (20); in the cold state of the vacuum pump (111), the female thread (18) has a nominal inner diameter (dni) smaller than the nominal inner diameter at the fixed end (24) of the Halbach stator sleeve (169) at the free end (22) of the Halbach stator sleeve (169), and the male thread (20) also has a nominal outer diameter (dna) smaller than the nominal outer diameter at the fixed end (24) of the Halbach stator sleeve (169) at the free end (22) of the Halbach stator sleeve (169) in the cold state of the vacuum pump (111); in the stable hot state during operation of the vacuum pump (111), the nominal inner diameter (dni) of the female thread (18) of the Halbach stator sleeve (169) decreases towards the free end (22) of the Halbach stator sleeve (169) so that a Halbach gap (175) having an essentially constant size is formed between the Halbach rotor sleeve (165) and the female thread (18) and between the fixed end (24) and the free end (22) of the Halbach stator sleeve (169), and / or In a thermally stable state during the operation of the vacuum pump (111), the nominal outer diameter (dna) of the male thread (20) of the Holbeck stator sleeve (169) decreases towards the free end (22) of the Holbeck stator sleeve (169) such that a radially Holbeck gap (173) having an essentially constant size is formed between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169) between the Holbeck rotor sleeve (163) and the male thread (20). The vacuum pump (111), characterized in that. [

2. ] The vacuum pump (111) according to claim 1, characterized in that the nominal inner diameter (dni) of the female thread (18) of the Holbeck stator sleeve (169) decreases gradually or stepwise towards the free end (22) of the Holbeck stator sleeve (169). [

3. ] The female thread (18) has a constant thread depth between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169), and the inner surface (12) of the Holbeck stator sleeve (169) defines the valley diameter (dki) of the female thread (18) that decreases towards the free end (22) of the Holbeck stator sleeve (169) in the cold state of the vacuum pump (111). The vacuum pump (111) according to claim 1 or 2, characterized in that. [

4. ] The inner surface (12) of the Holbeck stator sleeve (169) defines the valley diameter (dki) of the female thread (18) that is constant between the fixed end (24) and the free end (22) of the Holbeck stator sleeve (169) in the cold state of the vacuum pump (111), and the female thread (18) has a thread depth that increases towards the free end (22) of the Holbeck stator sleeve (169). The vacuum pump (111) according to claim 1 or 2, characterized in that. [

5. ] The vacuum pump (111) according to claim 1 or 2, characterized in that the nominal outer diameter (dna) of the male thread (18) of the Holbeck stator sleeve (169) decreases gradually or stepwise towards the free end (22) of the Holbeck stator sleeve (169). [

6. ] The male thread (20) has a constant thread depth between the fixed end (24) and the free end (22) of the Holvex status sleeve (169), and the outer surface (14) of the Holvex status sleeve (169) defines the root diameter (dka) of the male thread (20) that decreases towards the free end (22) of the Holvex status sleeve (169) in the cold state of the vacuum pump (111). The vacuum pump (111) according to claim 1 or 2, characterized in that.

7. The outer surface (14) of the Holvex status sleeve (169) defines the root diameter (dka) of the male thread (20) that is constant between the fixed end (24) and the free end (22) of the Holvex status sleeve (169) in the cold state of the vacuum pump (111), and the male thread (20) has a thread depth that decreases towards the free end (22) of the Holvex status sleeve (169). The vacuum pump (111) according to claim 1 or 2, characterized in that.

8. The Holvex status sleeve (169) has a constant wall thickness between the fixed end (24) and the free end (22) of the Holvex status sleeve (169), or The Holvex status sleeve (169) has a wall thickness that gradually or stepwise decreases towards the free end (22) of the Holvex status sleeve (169). The vacuum pump (111) according to claim 1 or 2, characterized in that.

9. The Holvex rotor has inner and outer Holvex rotor sleeves (163, 165) that concentrically surround the rotor shaft (153), the outer Holvex rotor sleeve (163) concentrically surrounds the Holvex status sleeve (169), and the Holvex status sleeve (169) concentrically surrounds the inner Holvex rotor sleeve (165). The vacuum pump (111) according to claim 1 or 2, characterized in that.

10. The hub (161) is attached to the rotor shaft (153), and the Holvex rotor sleeves (163, 165) are attached to the hub (161). The vacuum pump (111) according to claim 1 or 2, characterized in that.

11. The hub (161) is integrally formed with the rotor shaft (153), while on the other hand, the Holbeck rotor sleeves (163, 165) are attached to the hub (161), or the Holbeck rotor sleeves (163, 165) are integrally formed with the hub (161) and the hub (161) is attached to the rotor shaft (153). The vacuum pump (111) according to claim 1 or 2, characterized in that.

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