Turbomolecular vacuum pump with compact structure

Abstract

To reduce the axial structural height of a turbomolecular vacuum pump without this causing significant performance losses in the pumping speed performance of the pump.SOLUTION: A pump mechanism includes a plurality of turbomolecular pump stages which demonstrate pumping action, and which are connected to each other in series between a pump intake port 115 and a pump exhaust port 117. Each turbomolecular pump stage includes a rotor vane 155 and a stator vane 157 disposed downstream of the rotor vane. Each rotor vane includes a plurality of blades extending radially with a height H parallel to a rotor shaft 153, and each stator vane includes a plurality of blades extending radially with a height h parallel to the rotor shaft 153. Therein a ratio H / h of the turbomolecular pump stage located most upstream satisfying 3≤H / h≤5.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The invention relates to a turbomolecular vacuum pump which has a particularly compact design due to the inventive configuration of the most upstream turbomolecular pump stage, without this impairing the pumping speed performance of the pump. [Background technology]

[0002] The pumping speed of a turbomolecular vacuum pump is affected by many variables, including, among others, the geometry of the individual pump stages, and in particular the geometry of the rotor and stator vanes that together form each pair of pump stages.

[0003] Furthermore, the pumping speed of a turbomolecular vacuum pump depends on the number of pumping stages of the vacuum pump. Moreover, the more pumping stages that are connected in series or connected to one another to perform the pumping action, the greater the axial structural height of each pump. However, as a rule, attempts are made to keep the axial structural height of a turbomolecular vacuum pump as small as possible. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem underlying the present invention is to reduce the axial constructional height of a turbomolecular vacuum pump without this significantly impairing the pumping speed performance of the pump. [Means for solving the problem]

[0005] This problem is solved by a turbomolecular vacuum pump having the features of claim 1, in particular by the ratio H / h of the most upstream turbomolecular pump stage, where 3≦H / h≦5 holds. Here, H denotes the apparent blade height of the rotor blades measured parallel to the rotor shaft, while h denotes the apparent blade height of the stator vanes measured parallel to the rotor shaft. In this case, the blade height H of the rotor blades and the blade height h of the stator vanes of the most upstream turbomolecular pump stage are constant over the radial extension of each blade, which applies when the blades have an approximately rectangular shape and are inclined with respect to the axis of the rotor shaft. However, the blade height H of the rotor blades and the blade height h of the stator vanes may vary slightly in the radial direction. In this case, the variables H (or H1) and h (or h1) mentioned here relate to the average values ​​of the respective blades.

[0006] Specifically, the turbomolecular vacuum pump according to the present invention comprises a pump inlet, a pump outlet, and a pump mechanism driven by the rotor shaft for pumping process gas from the pump inlet to the pump outlet. The pump mechanism includes a plurality of serially connected turbomolecular pump stages for pumping between the pump inlet and the pump outlet, each turbomolecular pump stage having a rotor blade and a stator vane downstream of each rotor blade. Each rotor blade thus has a plurality of blades extending radially from the rotor shaft, each having a height H measured parallel to the rotor shaft, i.e., in the axial direction. Correspondingly, each stator vane has a plurality of radially extending blades, each having a height h measured parallel to the rotor shaft, i.e., in the radial direction.

[0007] According to the invention, it is assumed that in this case, the ratio H / h of the most upstream turbomolecular pump stage or the turbomolecular pump stage closest to the pump inlet in the flow direction satisfies 3≦H / h≦5. The blades of the most upstream stator vane therefore have a maximum height h that corresponds to at most one-third of the height H of the blades of the most upstream rotor blade. On the other hand, the blades of the most upstream stator vane have a minimum height h that corresponds to at least 20% of the height H of the blades of the most upstream rotor blade.

[0008] It is a widely accepted principle to construct the vanes and blades of each turbomolecular pump so that the height of the blades of each vane is somewhat less than the height of the blades of each blade, but in this case, the blades of each vane are usually dimensioned so that the axial height of the blades of each vane is as small as possible, but not less than half the axial height of the blades of the corresponding blade, since a decrease in the blade height of the vane located most upstream tends to result in a decrease in the exhaust velocity.

[0009] However, according to the present invention, it has been found through experiments that when the blade height h of the most upstream stator vane is selected to be significantly smaller than the blade height H of the corresponding rotor blade, the exhaust velocity can be maintained or even somewhat improved compared to conventional design criteria. Specifically, for ratio values ​​H / h such that approximately 2.5≦H / h, it was initially observed that as the stator blade height h decreases, the exhaust velocity continues to decrease as expected. However, from a ratio value H / h of approximately 3, the present invention confirmed that the exhaust velocity again exceeds expectations and reaches values ​​normally only attainable when the ratio H / h is approximately 1.7. Only when the stator blade height is selected to be only one-fifth or 20% of the blade height of the corresponding rotor blade, according to the present invention, has it been confirmed that a larger performance loss in exhaust velocity must be accepted in this case.

[0010] According to the invention, therefore, it is possible to design the rotor blades of the turbomolecular pump stage located most upstream at a lower height than previously known, without having to accept a significant loss in pumping speed. A turbomolecular vacuum pump designed according to the design principle according to the invention therefore has a smaller axial construction height while the pumping speed remains essentially the same or even improved.

[0011] Furthermore, it has been found that the pumping speed reaches a maximum in the range according to the invention of 3≦H / h≦5. Correspondingly, the ratio H / h of the most upstream turbomolecular pump stage preferably satisfies 3.2≦H / h≦4.5, in particular 3.3≦H / h≦4.1, particularly preferably 3.4≦H / h≦3.9.

[0012] In particular, the maximum pumping speed can be observed when the ratio H / h is about 3.5, and therefore, according to the invention, it is considered advantageous to work in an H / h range centered around 3.5. In short, since the focus is on maximizing the pumping speed, the ratio H / h of the most upstream turbomolecular pump stage should be selected so that 3.2≦H / h≦3.8, in particular 3.4≦H / h≦3.6, holds.

[0013] However, if the specific task focuses on reducing the axial height of the turbomolecular vacuum pump, then the ratio H / h of the most upstream turbomolecular pump stage should be selected so that 4.2≦H / h≦4.8, in particular 4.4≦H / h≦4.6, since only a slight loss in pumping speed is expected in this range. Only from 5≦H / h does the suction capacity decrease excessively. Therefore, according to the invention, the blade height of the most upstream stator vane should not be less than 20% of the blade height of the most upstream rotor blade.

[0014] The invention will now be described on the basis of exemplary advantageous embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] 1 shows a perspective view of a known turbomolecular pump; [Figure 2] FIG. 2 shows a bottom view of the turbomolecular pump of FIG. [Figure 3] 3 shows a cross-sectional view of a turbomolecular pump taken along the section line AA shown in FIG. 2. [Figure 4] 3 shows a cross-sectional view of the turbomolecular pump taken along the section line BB shown in FIG. 2. [Figure 5] 3 shows a cross-sectional view of the turbomolecular pump taken along the section line CC shown in FIG. 2. [Figure 6] A cross section corresponding to FIG. 3 is shown, with the height dimensions H or H1 and h or h1 of the turbomolecular pump stage located most upstream being indicated. DETAILED DESCRIPTION OF THE INVENTION

[0016] The turbomolecular pump 111 shown in Figure 1 has a pump inlet 115 surrounded by an inlet flange 113. A recipient (not shown) may be connected to the pump inlet 115 in a manner known per se. Gas coming from the recipient can be drawn in from the recipient via the pump inlet 115 and pumped through the pump to the pump outlet 117.

[0017] An auxiliary vacuum pump, such as a rotary vane pump, can be connected to the pump outlet 117. The inlet flange 113 forms the upper end of a 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, on the side of which an electronics housing 123 is arranged. The electronics housing 123 accommodates electrical and / or electronic components of the vacuum pump 111, for example for operating an electric motor 125 (see also FIG. 3) arranged in the vacuum pump. The electronics housing 123 is provided with a number of connections 127 for accessories. Furthermore, a data interface 129 (e.g., according to the RS485 standard) and a current supply connection 131 are arranged on the electronics housing 123.

[0018] There are also turbomolecular pumps that do not have this type of attached electronics housing, but are connected to external drive electronics.

[0019] The housing 119 of the turbomolecular pump 111 is provided with a ventilation inlet 133, particularly in the form of a ventilation valve. The vacuum pump 111 can be vented via the ventilation inlet 133. A seal gas connection 135 (also called a purge gas connection) is also arranged in the region of the lower part 121. A purge gas can be introduced into a motor chamber 137 via the seal gas connection 135 to protect the electric motor 125 (see, for example, FIG. 3 ) from the gas pumped by the pump. The electric motor 125 is accommodated in the motor chamber 137 of the vacuum pump 111. Two coolant connections 139 are also arranged in the lower part 121. One coolant connection serves as a coolant inlet and the other as an outlet. A coolant can be introduced into the vacuum pump for cooling purposes. The other turbomolecular vacuum pump present (not shown) is operated exclusively air-cooled.

[0020] The underside 141 of the vacuum pump can be used as a base, so that the vacuum pump 111 can be operated in a vertical position relative to the underside 141. Moreover, the vacuum pump 111 can be fixed to the recipient via the inlet flange 113 and thus operated in a suspended state, so to speak. Furthermore, the vacuum pump 111 can be configured so that it can be operated even when oriented in a different direction than that shown in FIG. 1. Vacuum pump configurations in which the underside 141 can be arranged not only facing downwards, but also facing sideways or upwards are also possible. In this case, any angle is conceivable in principle.

[0021] In particular, other turbomolecular vacuum pumps (not shown) that exist, which are larger than the pump shown, cannot be operated in a vertical position.

[0022] Various screws 143 are further arranged on the underside 141 shown in Figure 2. These screws 143 secure components of the vacuum pump, not specifically identified here, to one another. For example, a bearing cover 145 is secured to the underside 141.

[0023] Further fastening holes 147 are arranged in the underside 141. Via the fastening holes 147, the pump 111 can be fixed, for example, to a mounting surface. This is not possible with other existing turbomolecular vacuum pumps (not shown), in particular those larger than the pump shown.

[0024] 2 to 5 show a coolant line 148 in which a coolant can be circulated, the coolant being introduced and withdrawn via the coolant connection 139.

[0025] As shown in the cross-sectional views of Figures 3-5, the vacuum pump has multiple process gas pumping stages for pumping process gas acting on a pump inlet 115 to a pump outlet 117.

[0026] A rotor 149 is disposed within the housing 119. The rotor 149 has a rotor shaft 153 that is rotatable about a rotation axis 151.

[0027] The turbomolecular pump 111 has multiple turbomolecular pump stages connected in series to provide a pumping action. Each turbomolecular pump stage has multiple radially extending rotor blades 155 fixed to the rotor shaft 153 and multiple stator vanes 157 arranged between the rotor blades 155 and fixed within the housing 119. In this case, each rotor blade 155 and its adjacent stator vane 157 form one turbomolecular pump stage. The stator vanes 157 are held at a desired axial distance from each other by spacer rings 159.

[0028] The vacuum pump further comprises Holweck pump stages arranged radially inside and outside one another and connected in series to provide a pumping action. There are alternative turbomolecular vacuum pumps (not shown) that do not have Holweck pump stages.

[0029] The rotor of the Holweck pump stage includes a rotor hub 161 disposed on the rotor shaft 153 and two cylindrically sided Holweck rotor sleeves 163, 165 fixed to and supported by the rotor hub 161. The Holweck rotor sleeves 163, 165 are oriented coaxially with respect to the rotation axis 151 and engage radially with one another. Two cylindrically sided Holweck stator sleeves 167, 169 are also provided. The Holweck stator sleeves 167, 169 are likewise oriented coaxially with respect to the rotation axis 151 and engage radially with one another.

[0030] The pumping surfaces of the Holweck pump stages are formed by the side surfaces, i.e., the radially inner and / or outer surfaces of the Holweck rotor sleeves 163, 165 and the Holweck stator sleeves 167, 169. The radially inner surface of the outer Holweck stator sleeve 167 faces the radially outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together with this outer surface forms the first Holweck pump stage following the turbomolecular pump. The radially inner surface of the outer Holweck rotor sleeve 163 faces the radially outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with this outer surface forms the second Holweck pump stage. The radially inner surface of the inner Holweck stator sleeve 169 opposes the radially outer surface of the inner Holweck rotor sleeve 165, forming a radial Holweck gap 175, and together with this outer surface forms the third Holweck pump stage.

[0031] A radially extending channel may be provided at the lower end of the Holweck rotor sleeve 163. The radially outer Holweck gap 171 is connected to the central Holweck gap 173 via the channel. A further radially extending channel may be provided at the upper end of the inner Holweck stator sleeve 169. The central Holweck gap 173 is connected to the radially inner Holweck gap 175 via the channel. This allows multiple Holweck pump stages that engage with each other in series. A connecting channel 179 that leads to the exhaust port 117 may be provided at the lower end of the radially inner Holweck rotor sleeve 165.

[0032] The pumping surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves that extend axially and spirally around the rotation axis 151. On the other hand, the opposing sides of the Holweck rotor sleeves 163, 165 are smoothly formed and pump gas for operating the vacuum pump 111 forward in the Holweck grooves.

[0033] For the rotatable support of the rotor shaft 153, a rolling bearing 181 is provided in the region of the pump outlet 117 and a permanent magnetic bearing 183 is provided in the region of the pump inlet 115.

[0034] In the region of the rolling bearing 181, the rotor shaft 153 is provided with a conical splash nut 185. The splash nut 185 has an outer diameter that increases towards the rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping element of the working medium reservoir. In other existing turbomolecular vacuum pumps (not shown), a splash screw may be provided instead of a splash nut. This allows for various configurations to be realised, so that the term "splash tip" is also used in this context.

[0035] The working medium reservoir comprises a number of absorbent discs 187 stacked one above the other, which are impregnated with a working medium, e.g., a lubricant, for the rolling bearings 181.

[0036] During operation of the vacuum pump 111, the working medium is transferred by capillary action from the working medium reservoir via the scraping element to the rotating splash nut 185 and is then forced by centrifugal force along the splash nut 185 towards the increasing outer diameter of the splash nut 185 towards the rolling bearing 181, where it performs, for example, a lubrication function. The rolling bearing 181 and the working medium reservoir are enclosed in the vacuum pump by a trough-like insert 189 and a bearing cover 145.

[0037] The permanent magnet magnetic bearing 183 has a rotor-side bearing half 191 and a stator-side bearing half 193. Each half has a ring stack, which consists of multiple rings 195, 197 of permanent magnets stacked axially one above the other. The ring magnets 195, 197 face each other, forming a radial bearing gap 199, with the rotor-side ring magnet 195 positioned radially outward and the stator-side ring magnet 197 positioned radially inward. The magnetic field present in the bearing gap 199 generates a magnetic repulsion force between the ring magnets 195, 197. This repulsion force provides radial support for 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 radially outward. The stator-side ring magnet 197 is supported by a support portion 203 of the stator shaft 153. The support part 203 extends through the ring magnet 197 and is suspended on radial struts 205 of the housing 119. The rotor-side ring magnet 195 is fixed parallel to the rotation axis 151 by a cover element 207 connected to the support part 203. The stator-side ring magnet 197 is fixed in one direction parallel to the rotation axis 151 by a fixing ring 209 connected to the support part 203 and a fixing ring 211 connected to the support part 203. A disc spring 213 may further be provided between the fixing ring 211 and the ring magnet 197.

[0038] An emergency or safety bearing 215 is provided within the magnetic bearing. During normal operation of the vacuum pump, the emergency or safety bearing 215 runs free and only engages if the rotor 149 is displaced excessively radially relative to the stator, thereby forming a radial stop for the rotor 149 so that collisions between rotor-side and stator-side structures are prevented. The safety bearing 215 is configured as a non-lubricated rolling bearing and forms a radial gap with the rotor 149 and / or the stator. This gap prevents the safety bearing 215 from engaging during normal pump operation. The radial displacement that the safety bearing 215 engages is dimensioned to be sufficiently large so that the safety bearing 215 does not engage during normal operation of the vacuum pump, and at the same time is sufficiently small so that collisions between rotor-side and stator-side structures are prevented under all circumstances.

[0039] The vacuum pump 111 includes an electric motor 125 that rotates a rotor 149. The armature of the electric motor 125 is formed by the rotor 149. A rotor shaft 153 of the rotor 149 extends through a motor stator 217. A permanent magnet assembly may be disposed radially outward or embedded on the portion of the rotor shaft 153 that extends through the motor stator 217. The middle 219 defines a radial motor gap. Through the motor gap, the motor stator 217 and the permanent magnet assembly may magnetically interact to transmit a driving torque.

[0040] The motor stator 217 is fixed in the housing in a motor chamber 137 provided for the electric motor 125. A seal gas connection 135 allows a seal gas (also called purge gas, which may be, for example, air or nitrogen) to reach the motor chamber 137. The seal gas protects the electric motor 125 against process gases, for example corrosive parts of the process gas. The motor chamber 137 may be evacuated via the pump outlet 117, i.e., a vacuum pressure is applied to the motor chamber 137 at least approximately, which is achieved by an auxiliary vacuum pump connected to the pump outlet 117.

[0041] A so-called labyrinth seal 223, known per se, may further be provided between the rotor hub 161 and the wall 221 that defines the motor chamber 137. This achieves better sealing of the motor chamber 217, in particular with respect to the radially outer Holweck pump stages.

[0042] In the following, the configuration or dimensioning according to the invention of the aforementioned turbomolecular vacuum pump 111, in particular of its most upstream turbomolecular pumping stage, and the influence of this configuration on the pumping speed of the turbomolecular vacuum pump 111 will now be described.

[0043] As already mentioned above, the turbomolecular vacuum pump 111 has a number of turbomolecular pump stages connected in series to perform the pumping action, each of which is formed by a rotor blade 155 mounted on the rotor shaft 153 and a stator vane 157 located downstream of the corresponding rotor blade 155 and mounted in a fixed position in the housing 119. The pump stage located most upstream or closest to the pump inlet 115 is thus formed by the rotor blade 115 and the stator vane 157 located downstream of it. Downstream of this first pump stage is a second pump stage, which is again formed by the rotor blade 155 and the stator vane 157 located downstream of it.

[0044] In this case, each rotor blade 155 has a plurality of radially extending blades. The blades have a height H measured in the axial direction of the rotor shaft 153 when viewed in the cross-sectional view of FIG. 6 . Correspondingly, each stator vane 157 has a plurality of radially extending blades. The blades have a height h measured in the axial direction of the rotor shaft 153 when viewed in the cross-sectional view of FIG. 6 . Hereinafter, the blade height of the rotor blade 155 of the first or most upstream pump stage will be designated H1, and the blade height of the rotor blade 155 of the second or pump stage located downstream of the first pump stage will be designated H2. Correspondingly, the blade height of the stator vane 157 of the first pump stage will be designated h1. In this case, as can be seen from the cross-sectional view of FIG. 6 , the blade height H1 of the rotor blade 155 of the most upstream turbomolecular pump stage or the blade height h1 of the stator vane 157 of the most upstream turbomolecular pump stage is constant over the radial extension of the respective blade.

[0045] The sizing of the most upstream pumping stage of a conventional turbomolecular vacuum pump will now be described with reference to the following Tables 1 and 2, where Table 1 relates to the applicant's turbomolecular vacuum pump and Table 2 relates to a competitor's turbomolecular vacuum pump.

[0046] [Table 1]

[0047] [Table 2]

[0048] In both Tables 1 and 2, the third and fourth lines respectively list the blade heights H1 or h1 of the most upstream pump stages of different turbomolecular vacuum pumps, characterized in accordance with the corresponding ISO standard ISO 1609 by the diameter of their respective inlet flanges 113. The sixth line of each table lists the quotient H1 / h1, while the seventh line of each table lists the corresponding capture probability of N2 molecules. These values ​​are correlated with the pumping speed, and in particular, are proportional to the pumping speed. Therefore, the capture probability value for N2 molecules was chosen in this case because, unlike the pumping speed, this value does not depend on the size of the pump and thus the diameter of the inlet flange, allowing individual pumps to be directly compared with each other without depending on the diameter of the respective inlet flanges 113.

[0049] As can be seen from Tables 1 and 2, the ratio H1 / h1 usually ranges between approximately 1 and 2, which means that the blade height h1 of the most upstream stator vane 157 has traditionally been at least half the blade height H1 of the rotor blade 155 of the most upstream turbomolecular pump stage. This can also be seen from the following performance diagrams, where the capture probability as a function of the respective ratio H1 / h1 according to Tables 1 and 2 is shown by a triangular symbol:

[0050]

number

[0051] As can be seen from this, the molecular capture probability for N2 molecules tends to decrease as the H1 / h1 ratio increases. This has supported the assumption, based on the tendency for the exhaust speed to decrease, that from a technical point of view, it is not meaningful for the blades of the most upstream stator vane 157 to be formed with a height h1 that is smaller than half the height H1 of the blades of the rotor vanes 155 of the most upstream pump stage.

[0052] However, in accordance with the present invention, simulation tests have shown that the molecular capture probability or pumping speed for N2 molecules, after the aforementioned decrease, increases again as the H1 / h1 ratio approaches a range of approximately 3, as shown by the square symbols in the aforementioned performance diagram for a turbomolecular vacuum pump with an inlet flange diameter of DN100. Specific simulation results are given in Table 3 below, where the ratio H1 / h1 is given in the first row and the molecular capture probability for N2 molecules in the second row.

[0053] [Table 3]

[0054] As can be seen from the performance diagram in particular, from an H1 / h1 ratio value of about 3, as the H1 / h1 ratio increases, the molecular capture probability for N2 molecules and therefore the exhaust velocity first increase, specifically up to an H1 / h2 ratio of about 3.5, after which the molecular capture probability for N2 molecules or the exhaust velocity subsequently decrease again as the H1 / h1 ratio increases again. Because the molecular capture probability for N2 molecules and therefore the exhaust velocity decrease significantly only from an H1 / h1 ratio of about 5, it does not seem to make much sense in terms of performance loss in exhaust velocity to form the blade of the most upstream stator vane 157 with a height h1 that is less than 20% of the blade height H1 of the most upstream rotor blade 155.

[0055] If the emphasis is on reducing the axial structural height of the turbomolecular pump, it is recommended that the most upstream turbomolecular pump stage be configured so that 4.2≦H1 / h1≦4.8, in particular 4.4≦H1 / h1≦4.6, in accordance with the aforementioned simulation tests. On the other hand, if the emphasis is on maximizing the pumping speed, it is recommended that the most upstream turbomolecular pump stage be configured so that 3.2≦H1 / h1≦3.8, in particular 3.4≦H1 / h1≦3.6, in consideration of the aforementioned simulation tests.

[0056] Moreover, in any case, if the turbomolecular vacuum pump stage located most upstream is configured so that the blade height ratio satisfies 3≦H1 / h1≦5, the axial structural height of the turbomolecular vacuum pump 111 can be reduced without accepting a performance loss in the pumping speed. The present application relates to the invention described in the claims, but also includes the following as other aspects. 1. In a turbomolecular vacuum pump (111), a pump inlet (115), a pump outlet (117), and a pump mechanism driven by a rotor shaft (153) for pumping process gas from the pump inlet (115) to the pump outlet (117); The pump mechanism includes a plurality of turbomolecular pump stages connected in series to each other and performing a pumping action between the pump inlet (115) and the pump outlet (117), each of the turbomolecular pump stages having a rotor blade (155) and a stator vane (157) downstream of the rotor blade (155), each of the rotor blade (155) having a plurality of blades extending in a radial direction and having a height H parallel to the rotor shaft (153), and each of the stator vanes (157) having a plurality of blades extending in a radial direction and having a height h parallel to the rotor shaft (153), A turbomolecular vacuum pump (111) in which the ratio H / h of the turbomolecular pump stage located most upstream satisfies 3≦H / h≦5. 2. 2. The turbomolecular vacuum pump (111) according to claim 1, wherein the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.2≦H / h≦4.5, in particular the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.3≦H / h≦4.1, and preferably the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.4≦H / h≦3.9. 3. the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.2≦H / h≦3.8, in particular the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.4≦H / h≦3.6, or the ratio H / h of the most upstream turbomolecular pump stage satisfies 4.2≦H / h≦4.8, and in particular the ratio H / h of the most upstream turbomolecular pump stage satisfies 4.4≦H / h≦4.6, The turbomolecular vacuum pump (111) according to item 1 above. 4. 4. The turbomolecular vacuum pump (111) according to any one of 1 to 3 above, wherein the blade height of the rotor vanes (155) and the blade height of the stator vanes (157) of the turbomolecular pump stage located most upstream are constant over the radial extension length of each blade. [Explanation of symbols]

[0057] 111 Turbomolecular pump 113 Intake flange 115 Pump intake 117 Pump exhaust port 119 Housing 121 Lower part 123 Electronics Housing 125 electric motor 127 Accessory Connection 129 Data Interface 131 Current supply connection 133 Ventilation intake 135 Seal gas connection 137 Motor Room 139 Coolant Connection 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixed hole 148 Coolant line 149 Rotor 151 Rotation axis 153 rotor shaft 155 Moving blade 157 Stator blade 159 Spacer ring 161 rotor hub 163 Holbeck Rotor Sleeve 165 Holbeck Rotor Sleeve 167 Holbeck Sterling Sleeve 169 Holbeck Sterling Sleeve 171 Holbeck Gap 173 Holbeck Gap 175 Holbeck Gap 179 Connection Channels 181 Rolling bearings 183 Permanent magnet type magnetic bearing 185 Splash Nut 187 discs 189 Insert 191 Rotor side bearing half 193 Stator side bearing half 195 Ring Magnet 197 Ring Magnet 199 Bearing clearance 201 Support part 203 Support part 205 Radial Struts 207 Cover Elements 209 Support Ring 211 Fixing ring 213 Disc spring 215 Emergency bearings or safety bearings 217 Motor Stator 219 Intermediate Room 221 Wall section 223 Labyrinth Seal

Claims

1. In a turbomolecular vacuum pump (111), a pump inlet (115), a pump outlet (117), and a pump mechanism driven by a rotor shaft (153) for pumping process gas from the pump inlet (115) to the pump outlet (117); The pump mechanism includes a plurality of turbomolecular pump stages connected in series to perform a pumping action between the pump inlet (115) and the pump outlet (117), each of the turbomolecular pump stages having a rotor blade (155) and a stator vane (157) downstream of the rotor blade (155), each of the rotor blade (155) having a plurality of blades extending in a radial direction and having a height H parallel to the rotor shaft (153), and each of the stator vanes (157) having a plurality of blades extending in a radial direction and having a height h parallel to the rotor shaft (153), A turbomolecular vacuum pump (111) in which the ratio H / h of the turbomolecular pump stage located most upstream satisfies 3≦H / h≦5.

2. the ratio H / h of the most upstream turbomolecular pump stage is such that 3.2≦H / h≦4.5, or the ratio H / h of the most upstream turbomolecular pump stage is such that 3.3≦H / h≦4.1, or the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.4≦H / h≦3.9; A turbomolecular vacuum pump (111) according to claim 1.

3. the ratio H / h of the most upstream turbomolecular pump stage satisfies 3.2≦H / h≦3.8, or the ratio H / h of the most upstream turbomolecular pump stage is such that 3.4≦H / h≦3.6, or the ratio H / h of the most upstream turbomolecular pump stage is such that 4.2≦H / h≦4.8, or the ratio H / h of the most upstream turbomolecular pump stage satisfies 4.4≦H / h≦4.6; A turbomolecular vacuum pump (111) according to claim 1.

4. 4. The turbomolecular vacuum pump (111) according to claim 1, wherein the blade height of the rotor blades (155) and the blade height of the stator vanes (157) of the turbomolecular pump stage located most upstream are constant over the radial extension length of the respective blades.

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