EP4379216A1 - Turbomolecular vacuum pump with compact design - Google Patents

Abstract

The present invention relates to a turbomolecular vacuum pump with a pump inlet, a pump outlet and a pump mechanism driven by a rotor shaft for conveying a process gas from the pump inlet to the pump outlet. The pump mechanism has a plurality of turbomolecular pump stages connected in series between the pump inlet and the pump outlet, each with a rotor disk and a stator disk downstream of the rotor disk. Each rotor disk has a plurality of radially extending blades which have a height H parallel to the rotor shaft. In addition, each stator disk has a plurality of radially extending blades which have a height h parallel to the rotor shaft. The following applies to the ratio H / h of the turbomolecular pump stage located furthest upstream: 3 ≤ H / h ≤ 5.

Description

The present invention relates to a turbomolecular vacuum pump which, due to the inventive design of the most upstream turbomolecular pump stage, has a particularly compact design without this leading to a loss of performance in the pump's suction capacity.

The pumping speed of a turbomolecular vacuum pump is influenced by many parameters. These include the geometric parameters of the individual pump stages, in particular the geometric parameters of the rotor and stator disks, which together form a pump stage in pairs.

Furthermore, the pumping speed of a turbomolecular vacuum pump depends on the number of pump stages of the vacuum pump. However, the more pump stages are connected in series with one another, the greater the axial height of the respective pump becomes. On the other hand, there are fundamental efforts to keep the axial height of turbomolecular vacuum pumps as small as possible.

The invention is based on the object of reducing the axial height of a turbomolecular vacuum pump without this leading to significant performance losses in the pumping capacity of the pump.

This object is achieved by a turbomolecular vacuum pump having the features of claim 1 and in particular in that for the ratio H / h of the most upstream turbomolecular pump stage, the following applies: 3 ≤ H / h ≤ 5. Here, H denotes the height of the blades of the rotor disk in the view, measured parallel to the rotor shaft, whereas h denotes the height of the blades of the stator disk in the view, measured parallel to the rotor shaft. The height H of the blades of the rotor disk and the height h of the stator disk of the most upstream turbomolecular pump stage are generally constant over the radial extent of the respective blade, as is the case when the blades have a substantially rectangular shape and are inclined with respect to the axis of the rotor shaft. The height H of the blades of the rotor disk and the height h of the blades of the stator disk can, however, also vary slightly in the radial direction. In this case, the parameters H (or H ₁ ) and h (or h ₁ ) discussed here refer to the mean value of the respective blades.

Specifically, the turbomolecular vacuum pump according to the invention has a pump inlet, a pump outlet and a pump mechanism driven by a rotor shaft for conveying a process gas from the pump inlet to the pump outlet. Between the pump inlet and the pump outlet, the pump mechanism has several turbomolecular pump stages connected in series with one another for pumping purposes, each with a rotor disk and a stator disk downstream of the respective rotor disk. Each rotor disk has several blades extending radially from the rotor shaft, which have a height H when measured parallel to the rotor shaft and thus viewed in the axial direction. In a corresponding manner, each stator disk has several blades extending in the radial direction, which have a height h when measured parallel to the rotor shaft and thus viewed in the radial direction.

According to the invention, it is now provided that the ratio H / h of the most upstream turbomolecular pump stage or that For the turbomolecular pump stage located closest to the pump inlet in the direction of flow, the following applies: 3 ≤ H / h ≤ 5. The blades of the most upstream stator disk therefore have a maximum height h that corresponds to a maximum of one third of the height H of the blades of the most upstream rotor disk. On the other hand, the blades of the most upstream stator disk have a minimum height h that corresponds to at least 20% of the height H of the blades of the most upstream rotor disk.

Although it is generally accepted design principles to design the stator and rotor disks of a respective turbomolecular pump stage in such a way that the height of the vanes of the respective stator disk is slightly less than the height of the vanes of the respective rotor disk, the vanes of the respective stator disk are usually dimensioned in such a way that their axial height is not less than half the axial height of the vanes of the associated rotor disk, since a decrease in the suction capacity tends to be observed with decreasing vane height of the stator disk located furthest upstream.

However, according to the invention, it has now been recognized during tests that if the height h of the blades of the stator disk located furthest upstream is chosen to be very small in comparison to the height H of the rotor disk associated with the blades, the suction capacity can be maintained or even slightly improved compared to conventional design criteria. It was observed for ratio values H / h for which approximately 2.5 ≤ H / h applies that, as expected, the suction capacity initially continues to decrease with decreasing blade height h of the stator disks; however, from a ratio value of approximately 3 for the ratio H / h, it was surprisingly found according to the invention that the suction capacity again reaches values that are normally only achieved when the ratio H / h is approximately 1.7. Only when the height of the blades of the If the stator disk is chosen to be so small that it is only one fifth or 20% of the height of the blades of the corresponding rotor disk, it has been observed according to the invention that in this case greater performance losses in the suction capacity must be accepted.

According to the invention, it is thus possible to design the stator disk of the most upstream turbomolecular pump stage with a lower height than previously known, without having to accept significant performance losses in terms of suction capacity. A turbomolecular vacuum pump designed according to the design principles of the invention therefore has a lower axial height while maintaining the same or even improving the suction capacity.

According to the invention, it was further recognized that the pumping speed even reaches a maximum value in the interval according to the invention 3 ≤ H / h ≤ 5. Accordingly, the following preferably applies to the ratio H / h of the most upstream turbomolecular pump stage: 3.2 ≤ H / h ≤ 4.5, in particular 3.3 ≤ H / h ≤ 4.1 and in particular preferably 3.4 ≤ H / h ≤ 3.9.

In particular, the maximum pumping speed is observed when the ratio H / h is about 3.5, which is why it is considered advantageous according to the invention to work in H / h intervals with a focus on about 3.5. If the focus is therefore on maximizing the pumping speed, the ratio H / h of the most upstream turbomolecular pump stage should be selected such that: 3.2 ≤ H / h ≤ 3.8, in particular 3.4 ≤ H / h ≤ 3.6.

However, if the reduction of the axial height of the turbomolecular vacuum pump is a priority for certain tasks, the ratio H / h of the most upstream turbomolecular pump stage can be set so should be selected such that: 4.2 ≤ H / h ≤ 4.8, in particular 4.4 ≤ H / h ≤ 4.6, since in this range only slight losses in performance in the suction capacity are to be expected. Only from 5 ≤ H / h does the suction capacity decrease excessively, which is why according to the invention the height of the blades of the stator disk located furthest upstream should not be less than 20% of the height of the blades of the rotor disk located furthest upstream.

Fig. 1

eine perspektivische Ansicht einer Turbomolekularpumpe,

Fig. 2

eine Ansicht der Unterseite der Turbomolekularpumpe von Fig. 1,

Fig. 3

einen Querschnitt der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie A-A,

Fig. 4

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie B-B,

Fig. 5

eine Querschnittsansicht der Turbomolekularpumpe längs der in Fig. 2 gezeigten Schnittlinie C-C,

Fig. 6

einen der Fig. 3 entsprechenden Querschnitt, in den die Höhenabmessungen H bzw. H₁ sowie h bzw. h₁ der am weitesten stromaufwärts gelegenen Turbomolekular-Pumpstufe eingetragen sind.

The invention is described below by way of example using advantageous embodiments with reference to the attached figures. They show, each schematically:

Fig.1

a perspective view of a turbomolecular pump,

Fig.2

a view of the bottom of the turbomolecular pump from Fig.1 ,

Fig.3

a cross section of the turbomolecular pump along the Fig.2 shown section line AA,

Fig.4

a cross-sectional view of the turbomolecular pump along the Fig.2 shown cutting line BB,

Fig.5

a cross-sectional view of the turbomolecular pump along the Fig.2 shown section line CC,

Fig.6

one of the Fig.3 corresponding cross-section in which the height dimensions H or H ₁ as well as h or h ₁ of the most upstream turbomolecular pump stage are entered.

In the Fig.1 The turbomolecular pump 111 shown comprises a pump inlet 115 surrounded by an inlet flange 113, to which a recipient (not shown) can be connected in a manner known per se. The gas from the recipient can be sucked out of the recipient via the pump inlet 115 and conveyed through the pump to a pump outlet 117, to which a forevacuum pump, such as a rotary vane pump, can be connected.

The inlet flange 113 forms the vacuum pump in the alignment according to Fig.1 the upper end of the housing 119 of the vacuum pump 111. The housing 119 comprises a lower part 121, on which an electronics housing 123 is arranged on the side. Electrical and/or electronic components of the vacuum pump 111 are housed in the electronics housing 123, e.g. for operating an electric motor 125 arranged in the vacuum pump (see also Fig.3 ). Several connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, e.g. according to the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

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

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbomolecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121, a sealing gas connection 135, which is also referred to as a purge gas connection, is also arranged, via which purge gas can be fed to protect the electric motor 125 (see e.g. Fig.3 ) before the gas delivered by the pump can be let into the motor compartment 137, in which the electric motor 125 is housed in the vacuum pump 111. In the lower part 121, two coolant connections 139 are also arranged, wherein one of the coolant connections is provided as an inlet and the other coolant connection as an outlet for coolant that can be fed into the vacuum pump for cooling purposes. Other existing turbomolecular vacuum pumps (not shown) are operated exclusively with air cooling.

The lower side 141 of the vacuum pump can serve as a base so that the vacuum pump 111 can be operated standing on the underside 141. However, the vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and thus operated in a hanging position to a certain extent. In addition, the vacuum pump 111 can be designed in such a way that it can also be put into operation when it is aligned in a different way than in Fig.1 is shown. It is also possible to realize embodiments of the vacuum pump in which the underside 141 is not arranged facing downwards, but to the side or facing upwards. In principle, any angle is possible.

Other existing turbomolecular vacuum pumps (not shown), which are particularly larger than the pump shown here, cannot be operated in an upright position.

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

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 in particular larger than the pump shown here.

In the Figures 2 to 5 a coolant line 148 is shown in which the coolant introduced and discharged via the coolant connections 139 can circulate.

As the sectional views of the Figures 3 to 5 show, 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.

A rotor 149 is arranged in the housing 119 and has a rotor shaft 153 rotatable about a rotation axis 151.

The turbomolecular pump 111 comprises several turbomolecular pump stages connected in series with a pumping effect, with 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. A rotor disk 155 and an adjacent stator disk 157 each form a turbomolecular pump stage. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also comprises Holweck pump stages arranged one inside the other in the radial direction and connected in series to pump with one another. There are other turbomolecular vacuum pumps (not shown) that do not have Holweck pump stages.

The rotor of the Holweck pump stages comprises a rotor hub 161 arranged on the rotor shaft 153 and two cylinder-jacket-shaped Holweck rotor sleeves 163, 165 which are fastened to the rotor hub 161 and supported by it, which are oriented coaxially to the rotation axis 151 and are nested in one another in the radial direction. Furthermore, two cylinder-jacket-shaped Holweck stator sleeves 167, 169 which are also oriented coaxially to the rotation axis 151 and are nested in each other in the radial direction.

The pump-active surfaces of the Holweck pump stages are formed by the lateral surfaces, i.e. by 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 is opposite the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171, and together with this forms the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 is opposite the radial outer surface of the inner Holweck stator sleeve 169, forming a radial Holweck gap 173, and together with this forms 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 forming the third Holweck pumping stage.

A radially extending channel can be provided at the lower end of the Holweck rotor sleeve 163, via which the radially outer Holweck gap 171 is connected to the middle Holweck gap 173. In addition, a radially extending channel can be provided at the upper end of the inner Holweck stator sleeve 169, via which the middle Holweck gap 173 is connected to the radially inner Holweck gap 175. As a result, the nested Holweck pump stages are connected in series with one another. A connecting channel 179 to the outlet 117 can also be provided at the lower end of the radially inner Holweck rotor sleeve 165.

The above-mentioned pump-active surfaces of the Holweck stator sleeves 167, 169 each have a plurality of Holweck grooves extending spirally around the rotation axis 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and propel the gas in the Holweck grooves to operate the vacuum pump 111.

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.

In the area of the roller bearing 181, a conical spray nut 185 with an outer diameter that increases towards the roller bearing 181 is provided on the rotor shaft 153. The spray nut 185 is in sliding contact with at least one scraper of a fluid reservoir. In other existing turbomolecular vacuum pumps (not shown), a spray screw can be provided instead of a spray nut. Since different designs are thus possible, the term "spray tip" is also used in this context.

The operating fluid storage comprises several absorbent disks 187 stacked on top of each other, which are impregnated with an operating fluid for the rolling bearing 181, e.g. with a lubricant.

When the vacuum pump 111 is in operation, the operating fluid is transferred by capillary action from the operating fluid reservoir via the scraper to the rotating spray nut 185 and, as a result of the centrifugal force, is conveyed along the spray nut 185 in the direction of the increasing outer diameter of the spray nut 185 to the roller bearing 181, where it fulfills a lubricating function, for example. The roller bearing 181 and the operating fluid reservoir are enclosed in the vacuum pump by a trough-shaped insert 189 and the bearing cover 145.

The permanent magnet bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each of which has a ring stack of several permanent magnetic rings 195, 197 stacked on top of one another in the axial direction. The ring magnets 195, 197 lie opposite one another to form a radial bearing gap 199, with the rotor-side ring magnets 195 being arranged radially on the outside and the stator-side ring magnets 197 being arranged radially on the inside. The magnetic field present in the bearing gap 199 causes magnetic repulsion forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be radially supported. The rotor-side ring magnets 195 are carried by a support section 201 of the rotor shaft 153, which surrounds the ring magnets 195 radially on the outside. The stator-side ring magnets 197 are carried 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. The rotor-side ring magnets 195 are fixed parallel to the rotation axis 151 by a cover element 207 coupled to the carrier section 201. The stator-side ring magnets 197 are fixed parallel to the rotation axis 151 in one direction by a fastening ring 209 connected to the carrier section 203 and a fastening ring 211 connected to the carrier section 203. A disc spring 213 can also be provided between the fastening ring 211 and the ring magnets 197.

An emergency or safety bearing 215 is provided within the magnetic bearing, which runs idle without contact during normal operation of the vacuum pump 111 and only engages when there is an excessive radial deflection of the rotor 149 relative to the stator in order to form a radial stop for the rotor 149, so that a collision of the rotor-side structures with the stator-side structures is prevented. The safety bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and/or the stator, which causes the safety bearing 215 to be disengaged during normal pumping operation. The radial deflection at which the safety bearing 215 engages is large enough so that the safety bearing 215 does not engage during normal operation of the vacuum pump, and at the same time small enough so that a collision of the rotor-side structures with the stator-side structures is prevented under all circumstances.

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. Between the motor stator 217 and the section of the rotor 149 extending through the motor stator 217 there is an intermediate space 219 which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other to transmit the drive torque.

The motor stator 217 is fixed in the housing within the motor compartment 137 provided for the electric motor 125. A sealing gas, which is also referred to as purge gas and which can be air or nitrogen, for example, can enter the motor compartment 137 via the sealing gas connection 135. The electric motor 125 can be protected from process gas, e.g. from corrosive components of the process gas, via the sealing gas. The motor compartment 137 can also be evacuated via the pump outlet 117, i.e. the vacuum pressure in the motor compartment 137 is at least approximately the vacuum pressure caused by the forevacuum pump connected to the pump outlet 117.

Furthermore, a so-called labyrinth seal 223, which is known per se, can be provided between the rotor hub 161 and a wall 221 delimiting the motor compartment 137, in particular in order to achieve a better sealing of the motor compartment 217 with respect to the Holweck pump stages located radially outside.

The following describes the inventive design and dimensioning of the turbomolecular vacuum pump 111 described above and in particular its most upstream turbomolecular pump stage as well as the influence of this design on the pumping capacity of the turbomolecular vacuum pump 111.

As already explained above, the turbomolecular vacuum pump 111 comprises several turbomolecular pump stages connected in series for pumping purposes. Each of these pump stages is formed by a rotor disk 155 attached to the rotor shaft 153 and a stator disk 157, which is located downstream of the associated rotor disk 155 and is fixed in place on the housing 119. The pump stage located furthest upstream, or the pump stage closest to the pump inlet 115, is thus formed by a rotor disk 155 and a stator disk 157 located downstream of it. Downstream of this first pump stage is a second pump stage, which is also formed by a rotor disk 155 and a stator disk 157 located downstream of it.

Each rotor disk 155 has several radially extending blades, which in the cross-sectional view of the Fig.6 viewed in the axial direction of the rotor shaft 153 have a height H. In a corresponding manner, each stator disk 157 has several radially extending wings, which in the cross-sectional view of the Fig.6 viewed in the axial direction of the rotor shaft 153 have a height h. The height of the blades of the rotor disk 155 of the first or the most upstream pump stage is designated H ₁ and the height of the blades of the rotor disk 155 of the second or the pump stage downstream of the first pump stage is designated H _2. In a corresponding manner, the height of the blades of the stator disk 157 of the first pump stage is designated h _1. As can be seen from the cross-sectional view of the Fig.6 can be taken, the height H ₁ or h ₁ of the wings of the Rotor disk 155 or stator disk 157 of the most upstream turbomolecular pump stage is constant over the radial extent of the respective blades.

In the following, the dimensioning of the most upstream pumping stage of conventional turbomolecular vacuum pumps is discussed with reference to Tables 1 and 2 below, whereby Table 1 refers to turbomolecular vacuum pumps of the applicant and Table 2 refers to turbomolecular vacuum pumps of the competitor. Table 1 DN100 DN160 DN160 DN200 DN250 DN250 DN250 DN250 Pfeiffer Pfeiffer Pfeiffer Pfeiffer Pfeiffer Pfeiffer Pfeiffer Pfeiffer _H1 [mm] 11,50 8.00 11,50 15.00 15.00 15.00 16,00 15.00 _h1 [mm] 6.50 4.00 6.50 8.00 8.00 9.00 9.00 8.00 _H2 [mm] 6.50 4.00 5.00 6.50 7.00 10.00 13,00 10.50 Ratio H ₁ / h ₁ 1.77 2 1.77 1.88 1.88 1.67 1.78 1.88 Capture probability of a N2 molecule 44% 40% 43% 39% 43% 44% 44% 41% DN100 DN63 DN63 DN100 DN250 Competition Competition Competition Competition Competition _H1 [mm] 8.00 6.10 4.79 11.69 24,00 _h1 [mm] 3.25 3.10 4.10 8.00 16,00 _H2 [mm] 3.80 1.70 2.76 5.12 15.00 Ratio H ₁ / h ₁ 2.46 1.97 1.17 1.46 1.5 Capture probability of a N2 molecule 39% 41% 43% 40% 42%

The third and fourth rows of Tables 1 and 2 respectively list the blade heights H ₁ and h ₁ of the furthest upstream pump stage of different turbomolecular vacuum pumps, which are characterized by the diameter of their respective inlet flange 113 in accordance with the relevant ISO standard ISO 1609. The sixth column of each table lists the quotient H ₁ / h ₁ , whereas the seventh row of the respective table lists the associated capture probability of an N ₂ molecule. This value correlates with the pumping speed and, in particular, is linear to the pumping speed. The size of the capture probability of an N ₂ molecule was chosen here because, unlike the pumping speed, this value is independent of the size of the pump and thus of the diameter of the inlet flange 113, so that the individual pumps can be directly compared with one another regardless of the diameter of the respective inlet flange 113.

As can be seen from Tables 1 and 2, the ratio H ₁ / h ₁ is usually in the range between 1 and 2, which means that so far the height h ₁ of the blades of the most upstream Stator disk 157 was at least half as high as the height H ₁ of the blades of the rotor disk 155 of the most upstream turbomolecular pump stage. This can also be seen from the following performance diagram, in which the capture probability according to Tables 1 and 2 is illustrated with triangular symbols as a function of the respective ratio H ₁ / h ₁ .

As can be seen from this, the molecular capture probability for an N ₂ molecule tends to decrease with increasing H ₁ / h ₁ ratio, which had previously supported the assumption that, due to the tendency for the suction capacity to decrease, it is not technically sensible to design the vanes of the most upstream stator disk 157 with a height h ₁ that is less than half the height H ₁ of the vanes of the rotor disk 155 of the most upstream pump stage.

However, according to the invention, it has now been found through simulation tests that the molecular capture probability for N ₂ molecules or the pumping speed increases again after the previously described decrease with increasing approach to H ₁ / h ₁ ratios in the order of magnitude of about 3, as is illustrated by the square symbols in the above performance diagram for a turbomolecular vacuum pump with an inlet flange diameter of DN100. The specific simulation results are listed in Table 3 below, which lists the H ₁ / h ₁ ratio in the first line and the molecular capture probability for N ₂ molecules in the second line. Table 3 3 3.5 3.83 4 4.5 5 5.5 46% 47% 45% 44% 40% 35% 27%

As can be seen from this and in particular from the performance diagram, from an H ₁ / h ₁ ratio of about 3, the molecular capture probability for N ₂ molecules and thus the suction capacity initially increases with increasing H ₁ / h ₁ ratio, up to an H ₁ / h ₁ ratio of about 3.5, whereupon the molecular capture probability for N ₂ molecules and the suction capacity subsequently decrease again with further increasing H ₁ / h ₁ ratio. Only from an H ₁ / h ₁ ratio of about 5 does the molecular capture probability for N ₂ molecules and thus the suction capacity decrease noticeably, so that in view of the performance losses of a suction capacity it seems less sensible to design the blades of the most upstream stator disk 157 with a height h ₁ that is less than 20% of the height H ₁ of the blades of the most upstream rotor disk 155.

If the focus is on reducing the axial height of the turbomolecular pump, then, in view of the simulation tests explained above, it is advisable to design the most upstream turbomolecular pump stage in such a way that 4.2 ≤ H ₁ / h ₁ ≤ 4.8, in particular 4.4 ≤ H ₁ / h ₁ ≤ 4.6 applies. If, on the other hand, the focus is on maximizing the pumping speed, then, taking into account the simulation tests explained above, it is advisable to design the most upstream turbomolecular pump stage in such a way that 3.2 ≤ H ₁ / h ₁ ≤ 3.8, in particular 3.4 ≤ H ₁ / h ₁ ≤ 3.6 applies.

In any case, however, the axial height of the turbomolecular vacuum pump 111 can be reduced without having to accept a loss in performance in terms of pumping capacity if the turbomolecular pump stage located furthest upstream is designed in such a way that the following applies to the blade height ratio: 3 ≤ H ₁ / h ₁ ≤ 5.

List of reference symbols

111

Turbomolecular pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

Housing

121

Bottom part

123

Electronic housing

125

Electric motor

127

Accessory connection

129

Data interface

131

Power supply connection

133

Flood inlet

135

Sealing gas connection

137

Engine compartment

139

Coolant connection

141

bottom

143

screw

145

Bearing cap

147

Mounting hole

148

Coolant line

149

rotor

151

Rotation axis

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

roller bearing

183

Permanent magnet bearings

185

Injection nut

187

disc

189

Mission

191

rotor-side bearing half

193

stator side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Carrier section

203

Carrier section

205

radial strut

207

Cover element

209

Support ring

211

Mounting ring

213

Disc spring

215

Emergency or rescue camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

Claims (4)

Turbomolecular vacuum pump (111) with a pump inlet (115), a pump outlet (117) and a pump mechanism driven by a rotor shaft (153) for conveying a process gas from the pump inlet (115) to the pump outlet (117), wherein the pump mechanism between the pump inlet (115) and the pump outlet (117) has a plurality of turbomolecular pump stages connected in series with one another for pumping purposes, each with a rotor disk (155) and a stator disk (157) downstream of the rotor disk (155), wherein each rotor disk (155) has a plurality of radially extending vanes which have a height H parallel to the rotor shaft (153), and wherein each stator disk (157) has a plurality of radially extending vanes which have a height h parallel to the rotor shaft (153);
where the ratio H / h of the most upstream turbomolecular pump stage is: 3 ≤ H / h ≤ 5. Turbomolecular vacuum pump (111) according to claim 1,
where the ratio H/h of the most upstream turbomolecular pumping stage is: 3.2 ≤ H/h ≤ 4.5, where in particular the ratio H/h of the most upstream turbomolecular pumping stage is: 3.3 ≤ H/h ≤ 4.1, and where preferably the ratio H/h of the most upstream turbomolecular pumping stage is: 3.4 ≤ H/h ≤ 3.9. Turbomolecular vacuum pump (111) according to claim 1, where the ratio H / h of the most upstream turbomolecular pump stage is: 3.2 ≤ H / h ≤ 3.8, where in particular for the ratio H / h of the most upstream turbomolecular pump stage is: 3.4 ≤ H / h ≤ 3.6; or where the ratio H / h of the most upstream turbomolecular pumping stage is: 4.2 ≤ H / h ≤ 4.8, where in particular the ratio H / h of the most upstream turbomolecular pumping stage is: 4.4 ≤ H / h ≤ 4.6. Turbomolecular vacuum pump (111) according to one of the preceding claims,
wherein the height of the vanes of the rotor disk (155) and the stator disk (157) of the most upstream turbomolecular pump stage is constant over the radial extent of the respective vane.

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