EP3767109B1 - Vacuum system - Google Patents

Description

The present invention relates to a vacuum system, comprising a vacuum pump, in particular a turbo-molecular pump, and at least one vacuum chamber, the vacuum pump comprising: at least a first and a second inlet and a common outlet; at least one first and one second pumping stage, each having at least one rotor element arranged on a common rotor, the first inlet being connected to an upstream end of the first pumping stage and the second inlet being connected to an upstream end of the second pumping stage; wherein the downstream end of the first pumping stage is connected to the upstream end of the second pumping stage bypassing the second inlet.

the EP 3 112 688 A1 discloses a vacuum system comprising a vacuum pump and a plurality of vacuum chambers, the vacuum pump comprising two pumping stages and two inlets, the two inlets being connected to the same vacuum chamber.

In an exemplary vacuum application, a vacuum chamber with a particularly high pumping speed is to be evacuated. The available installation space for a vacuum pump used for this purpose, in particular a turbo molecular pump, is very limited. In particular, the installation space is limited in one direction radially with respect to a rotor axis. In principle, the installation dimensions of the pump should be as compact as possible, the axial length being able to be less limited relative to the rotor diameter, in particular even being greater, since the internals in certain applications, such as mass spectrometry, also have a certain installation length.

It is therefore an object of the invention to provide a particularly high pumping speed for a vacuum chamber, in particular with limited installation space for the vacuum pump.

This object is achieved by a vacuum system according to claim 1, and in particular in that the first inlet and the second inlet are connected to the same vacuum chamber.

This leads to a significant increase in the pumping speed and thus to a particularly low pressure in the chamber. This increase in pumping speed can, however, be achieved essentially without the need to increase the rotor diameter and increase the rotor speed. Exemplary calculations suggest an increase in the pumping speed with a constant rotor diameter and constant rotor speed of up to 50% or even up to 80%.

In this context, it may be advantageous or, for certain constructions, necessary to increase the rotor length compared to a known construction, for example in order to provide a steering element, an additional pumping stage and / or an additional inlet. The installation space in the axial length is in some applications less critical than the pump or rotor diameter. In addition, a change, in particular an increase, in the rotor length has only a smaller influence on the dynamic behavior of the rotor than a change in the diameter, which is primarily due to the high speeds of vacuum pumps, in particular turbo-molecular pumps. However, since the increase in pumping speed according to the invention in particular allows the rotor diameter and rotor speed to be largely retained, the dynamic properties of the rotor also only change to a small extent, so that at best bearing concepts and components from known constructions can also be used or so in general relatively low or easily controllable requirements are placed on the storage. This means that the costs can also be kept within limits.

In general, the invention therefore offers a particularly good pumping speed for the vacuum chamber with simple means, specifically in particular without or essentially without such disadvantages as are associated with conventional approaches to increasing pumping speed.

The advantages mentioned above are achieved in particular in that the volume flows from the first pump stage and from the second inlet essentially only combine in the region of the second pump stage, in particular an upstream rotor element. In particular, the gas coming from the first pumping stage is led directly to the second pumping stage, bypassing the second inlet.

According to the invention, both the first inlet and the second inlet are connected to one and the same chamber, ie between the first inlet and the second inlet no structures may be provided on the chamber side that would lead to the areas connected to the respective inlet being viewed as separate chambers are. In particular, the inlets should not be separated on the chamber side by structures with a low conductance, such as a wall, even if this has a small opening or aperture.

A preferred application of the invention is in a mass spectrometry system. Such a chamber usually has a plurality of vacuum chambers, a first vacuum chamber having a small fluid connection to an adjacent, second chamber via a diaphragm. However, the absolute pressures in the chambers are different, among other things due to the fundamentally small orifice. It makes it possible to maintain the pressure difference that is built up by one or more vacuum pumps and / or pump stages. Separate chambers are also present in particular when there is a fluid connection, but this has a low conductance or the pumping speed is small in relation to the conductance. In the context of the invention, on the other hand, a single chamber is characterized in particular by an essentially homogeneous pressure and / or by a high chamber-side conductance between the first and the second inlet.

A conductance L is preferably defined in the chamber between the first inlet and the second inlet, the pumping speed at both inlets together being a total pumping speed S, with a ratio S / L <300, in particular <100, in particular <50, in particular <10 , is. These values relate in particular to the gas type nitrogen at room temperature.

According to one embodiment of the invention, a steering or guiding element can be provided to prevent a gas flow from a downstream end of the first pumping stage to the second inlet, wherein in the following, only the steering element is referred to in a simplified manner, but the guiding element can also be meant. Such a can be designed, for example, as a wall and / or plate between the downstream end of the first pumping stage and the second inlet. The steering element preferably extends perpendicular to the rotor axis. However, the steering element does not necessarily produce a perfect seal. Rather, the steering means must at least substantially prevent or hinder a gas flow from the downstream end of the first pumping stage to the second inlet. The steering element can, for example, be designed as a deflecting element, but in principle does not necessarily have to give the gas a different direction. Rather, it is essential that the gas flow to the second inlet is avoided or at least hindered. In certain embodiments, a wall of a channel can also form the steering element or be connected to it.

The steering element can, for example, be designed as a static element and / or attached to a housing of the vacuum pump. In such a case, for example, a gap can be provided between the deflection means and the rotor, in particular in order to take into account a rotor deflection during operation. Such a gap naturally allows a small leakage flow. Nevertheless, the deflection means essentially retains its function, since the gap can in particular be kept small in relation to the suction capacity.

The downstream end of the first pump stage can be connected to the upstream end of the second pump stage, for example by a channel. The channel defines a flow path for the gas, namely in particular not towards the inlet, but towards the upstream end of the second pump stage. The channel can, for example, be part of a steering element or be connected to it, in particular in one piece. In particular, an outlet end of the channel, in particular axially and / or directly, is directed towards an upstream end of the second pump stage, in particular a turbo rotor disk of the second pump stage. In general, the downstream end of the first pump stage is preferably connected directly to the upstream end of the second pump stage, bypassing the second inlet

According to one embodiment it is provided that the channel is arranged eccentrically with respect to the rotor. As a result, the gas is advantageously pumped out of the channel. In particular if the second pump stage has at least one turbo rotor disk, this approach is advantageous since the respective rotor blades eccentrically or radially outside have a greater speed than inside and thus the gas is pumped out particularly well outside or eccentrically. The channel can be arranged such that the rotor is arranged outside the channel. However, an eccentric arrangement of the duct does not rule out that the rotor runs through the channel, but the axis of rotation of the rotor and the longitudinal or central axis of the channel do not coincide.

As an alternative or in addition, the channel can also be arranged concentrically with respect to the rotor and / or surround the rotor. This results in a particularly simple construction in particular.

In principle, several channels and, for example, a concentric and an eccentric channel can be provided.

In a further embodiment, the channel is arranged opposite the second inlet with respect to the rotor. This results in a large distance between the channel, in particular the channel outlet, and the second inlet, which in a simple manner reduces the probability of the gas molecules escaping from the channel through the second inlet, that is to say improves the pumping effect.

In a further embodiment, the pump comprises a housing which defines a pump chamber in which the rotor elements of the pump stages are arranged, the channel being arranged in the pump chamber. In this way, a particularly space-saving design, particularly small in the radial direction, can be achieved. The pump chamber is preferably cylindrical. In particular, the channel can be arranged within an envelope of the pump stages.

As an alternative or in addition, the channel can also be arranged, for example, at least in some areas outside the pump chamber. For example, the channel can be formed at least partially in a housing body, in a separate rigid block and / or a hose or pipe. In principle, several channels and / or guide elements can also be provided, for example can also be designed differently. This can be advantageous depending on the manufacturing process or the arrangement of the inlets.

In one embodiment, the second pumping stage has a turbo rotor disk at its upstream end, which has a first axial section disposed upstream and a second axial section disposed downstream of the first axial section, the rotor disk having a smaller active pumping cross-section in the first axial section than in the second axial section wherein the downstream end of the first pumping stage is connected to the second axial section, at least partially bypassing the first axial section, in particular by a channel. This particularly effectively prevents particles from reaching the second inlet from the downstream end of the first pump stage and / or from a channel outlet. This is because the particles that come from the first pump stage, in particular from the channel, and flow out radially or flow back within the second pump stage, can for the most part experience a movement impulse in the pumping direction and are therefore more likely to be pumped out. The pumping effect is thus further improved.

For example, it can also be provided that the second pump stage has at least two turbo rotor disks, a first rotor disk arranged upstream having a smaller active pumping diameter than a second rotor disk arranged downstream of the first rotor disk, the downstream end of the first pump stage, at least partially bypassing the first rotor disk is connected to the second rotor disk. This also particularly effectively prevents particles from reaching the downstream end of the first pumping stage and / or from a channel outlet to the second inlet, whereby the pumping action is further improved.

The second pump stage can, for example, have a larger rotor diameter than the first pump stage or, conversely, the first pump stage can have a smaller rotor diameter than the second pump stage. In this way, the pumping speed of the second pumping stage can advantageously be adjusted to the second inlet on the one hand and the gas coming from the first pumping stage on the other hand, so that overall an advantageously high pumping speed can be achieved. For example, in the event that further pump stages are provided, for example the first pump stage can have a smaller rotor diameter than all other pump stages and / or the second pump stage can have a larger rotor diameter than all other pump stages.

A second pump stage with a larger rotor diameter can prove to be particularly advantageous if the first and second inlets are arranged axially to the rotor axis. This enables a further increase in the pumping speed. But even with two radial inlets, the second inlet can be further improved in terms of pumping speed with a larger second pumping stage.

All inlets, in particular the first and / or the second inlet, can in principle be designed, for example, as a radial and / or axial inlet. It can be advantageous, for example, for the first and second inlets to be designed as radial inlets. Alternatively, at least one of the two can be designed as an axial inlet. In particular with the axial arrangement, better conductance values or an improved pumping speed can be achieved.

Particularly advantageous is an, in particular completely, arrangement of the second inlet around the first inlet. But even with two radial inlets, advantageous increases in pumping speed can already be achieved. In general, the second inlet can be, for example, an axial inlet and can be arranged radially beyond the first pump stage, that is to say radially outside the first pump stage. This achieves a particularly good conductance.

In principle, an inlet can also have several inlet openings. In this way, a better conductance and a better pumping speed can be achieved, especially with the axial arrangement

In a further advantageous embodiment, a first rotor element and a downstream of the first, adjacent, second rotor element are provided in the first and / or second pumping stage, wherein the second rotor element has a lower pumping speed than the first rotor element and / or wherein the second rotor element has a has greater compression than the first rotor element. As a result, the overall suction capacity can be further improved.

In principle, the second pump stage can be constructed differently than the first.

According to a further development, the second pump stage has at least two, in particular first, rotor elements with essentially the same pumping speed on the upstream side. In particular, an adjacent, second rotor element is provided downstream of the first rotor elements, wherein the second rotor element has a lower suction capacity than the first rotor elements and / or wherein the second rotor element has a greater compression than the first rotor elements.

In principle, the first and / or the second pump stage or also further pump stages can preferably be designed as molecular pump stages, in particular turbo-molecular, Holweck or Siegbahn pump stages. In particular, all or individual rotor elements can be designed as turbo-rotor elements or turbo-rotor disks. The pump can basically comprise further pump stages, in particular those that are connected to the common outlet and / or those with rotor elements that are arranged on the common rotor are. The pump can also have further inlets which are assigned to the further pump stages and which are preferably connected to a different chamber than the first and second inlets.

The object of the invention is also achieved by using a vacuum pump, in particular a turbo-molecular pump, for evacuating at least one vacuum chamber, according to claim 15. The vacuum pump comprises: at least a first and a second inlet and a common outlet; at least one first and one second pumping stage each having at least one rotor element arranged on a common rotor, the first inlet being connected to an upstream end of the first pumping stage and the second inlet being connected to an upstream end of the second pumping stage; wherein the downstream end of the first pumping stage is connected to the upstream end of the second pumping stage bypassing the second inlet. The first inlet and the second inlet are connected to the same vacuum chamber.

According to a second, independent aspect, the object of the invention is also achieved by a vacuum pump, in particular a turbo-molecular pump, comprising: at least a first and a second inlet and a common outlet; at least one first and one second pumping stage, each having at least one rotor element arranged on a common rotor, the first inlet being connected to an upstream end of the first pumping stage and the second inlet being connected to an upstream end of the second pumping stage; deflection means for preventing gas flow from the downstream end of the first pumping stage to the second inlet; and a channel connecting the downstream end of the first pumping stage to a location which is located downstream of at least one rotor element of the second pumping stage in the flow direction; wherein the channel is at least partially formed in the rotor shaft.

A vacuum system comprising such a vacuum pump and at least one vacuum chamber is particularly advantageous, the first inlet and the second inlet being connected to the same vacuum chamber. A corresponding use of such a vacuum pump is also advantageous.

According to a further development, it is particularly advantageous not to let the gas flow flow in at the first rotor element, in particular on the first rotor disk, the second pump stage, in particular disk pack, but rather the gas flow through suitable opening cross-sections in the shaft at a point with a higher compression, in particular to a third inlet downstream of the second pumping stage, in particular a high vacuum port.

The gas can in particular be guided at least as far as behind the first rotor element, in particular the first rotor disk, preferably behind the first rotor disk and the first stator disk.

In particular in the event that good conductance values can be achieved in the channel formed in the rotor shaft, the gas can advantageously be admitted behind the second, third or last rotor and / or stator disk.

The channel in the rotor shaft can in particular be designed as a groove. In particular, several channels or grooves can be provided. The channel or channels extend in particular axially past at least the first rotor disk, preferably all of the rotor disks of the second pump stage.

The channel can, for example, also be formed by a bore, in particular a hollow bore, in the shaft. However, in particular the channel as a recess on the is advantageous in terms of production technology and / or can be implemented with less effort Surface of the shaft, in particular wherein the recess extends axially along the shaft.

It goes without saying that the developments and individual features of the different aspects described herein can advantageously be used to develop the other aspects in each case, as far as technically sensible.

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

ein erfindungsgemäßes Vakuumsystem.

Fig. 7

zeigt ein weiteres erfindungsgemäßes Vakuumsystem.

Fig. 8

zeigt ein Lenkelement für ein Vakuumsystem.

Fig. 9 bis 17

zeigen jeweils eine Ausführungsform einer Vakuumpumpe für ein erfindungsgemäßes Vakuumsystem.

Fig. 18 und 19

zeigen Ausführungsformen einer Vakuumpumpe nach dem zweiten Aspekt der Erfindung.

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

Fig. 1

a perspective view of a turbo molecular pump,

Fig. 2

a view of the underside of the turbo molecular pump of FIG Fig. 1 ,

Fig. 3

a cross section of the turbo molecular pump along the in Fig. 2 shown section line AA,

Fig. 4

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line BB,

Fig. 5

a cross-sectional view of the turbo molecular pump along the line in FIG Fig. 2 shown section line CC,

Fig. 6

a vacuum system according to the invention.

Fig. 7

shows a further vacuum system according to the invention.

Fig. 8

shows a steering element for a vacuum system.

Figures 9 to 17

each show an embodiment of a vacuum pump for a vacuum system according to the invention.

Figures 18 and 19

show embodiments of a vacuum pump according to the second aspect of the invention.

In the Fig. 1 The turbo molecular pump 111 shown comprises a pump inlet 115 which is surrounded by an inlet flange 113 and 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 backing pump, such as a rotary vane pump, can be connected.

In the orientation of the vacuum pump, the inlet flange 113 forms according to FIG 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 laterally. Electrical and / or electronic components of the vacuum pump 111 are accommodated in the electronics housing 123, for example for operating an electric motor 125 arranged in the vacuum pump. A plurality of connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, for example in accordance with the RS485 standard, and a power supply connection 131 are arranged on the electronics housing 123.

A flood inlet 133, in particular in the form of a flood valve, is provided on the housing 119 of the turbo molecular pump 111, via which the vacuum pump 111 can be flooded. In the area of the lower part 121 there is also a sealing gas connection 135, which is also referred to as a purging gas connection, via which purging gas is used to protect the electric motor 125 (see e.g. Fig. 3 ) can be brought into the engine compartment 137, in which the electric motor 125 in the vacuum pump 111 is accommodated, before the gas conveyed by the pump. in the Lower part 121 also has two coolant connections 139, one of the coolant connections being provided as an inlet and the other coolant connection being provided as an outlet for coolant, which can be fed into the vacuum pump for cooling purposes.

The lower side 141 of the vacuum pump can serve as a standing surface, so that the vacuum pump 111 can be operated standing on the lower side 141. The vacuum pump 111 can, however, also be attached to a recipient via the inlet flange 113 and can thus be operated in a suspended manner, as it were. In addition, the vacuum pump 111 can be designed in such a way that it can also be put into operation when it is oriented in a different way than in FIG Fig. 1 is shown. Embodiments of the vacuum pump can also be implemented in which the underside 141 cannot be arranged facing downwards, but facing to the side or facing upwards.

At the bottom 141, which in Fig. 2 is shown, various screws 143 are also arranged by means of which components of the vacuum pump not specified here are attached to one another. For example, a bearing cap 145 is attached to the underside 141.

Fastening bores 147 are also arranged on the underside 141, via which the pump 111 can be fastened to a support surface, for example.

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.

Like the sectional views of the Figures 3 to 5 show, the vacuum pump comprises several process gas pump 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 an axis of rotation 151.

The turbo-molecular pump 111 comprises several turbo-molecular pump stages connected in series with one another with several radial rotor disks 155 fastened 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 one Pumping 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 which are arranged one inside the other in the radial direction and are connected in series with one another for effective pumping. 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 attached to the rotor hub 161 and carried by the latter, which are oriented coaxially to the axis of rotation 151 and nested in one another in the radial direction. Furthermore, two cylinder jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and, viewed in the radial direction, are nested inside one another.

The active pumping surfaces of the Holweck pump stages are formed by the jacket surfaces, that is to say 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 lies on the radial outer surface of the outer Holweck rotor sleeve 163 with the formation of a radial Holweck gap 171 opposite and with this forms the first Holweck pump stage following the turbo molecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169 with the formation of a radial Holweck gap 173 and forms with this a second Holweck pumping 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 with the formation of a radial Holweck gap 175 and with this forms the third Holweck pumping stage.

At the lower end of the Holweck rotor sleeve 163, a radially running channel can be provided, via which the radially outer Holweck gap 171 is connected to the central Holweck gap 173. In addition, a radially running 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 aforementioned pump-active surfaces of the Holweck stator sleeves 163, 165 each have a plurality of Holweck grooves running spirally around the axis of rotation 151 in the axial direction, while the opposite lateral surfaces of the Holweck rotor sleeves 163, 165 are smooth and the gas for operating the Drive vacuum pump 111 in the Holweck grooves.

For the rotatable mounting of the rotor shaft 153, a roller bearing 181 is provided in the area of the pump outlet 117 and a permanent magnetic bearing 183 in the area of the pump inlet 115.

In the area of the roller bearing 181, a conical injection molded nut 185 is provided on the rotor shaft 153 with an outer diameter that increases towards the roller bearing 181. The injection-molded nut 185 is in sliding contact with at least one stripper of an operating medium reservoir. The operating medium reservoir comprises several absorbent disks 187 stacked on top of one another, which are impregnated with an operating medium for the roller bearing 181, e.g. with a lubricant.

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

The permanent magnetic bearing 183 comprises a rotor-side bearing half 191 and a stator-side bearing half 193, each of which comprises 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 are opposite one another with the formation of a radial bearing gap 199, 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 repulsive forces between the ring magnets 195, 197, which cause the rotor shaft 153 to be supported radially. The rotor-side ring magnets 195 are carried by a carrier 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 ring magnets 195 on the rotor side are parallel to the axis of rotation 151 by means of a cover element coupled to the carrier section 203 207 set. The stator-side ring magnets 197 are fixed parallel to the axis of rotation 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 plate spring 213 can also be provided between the fastening ring 211 and the ring magnet 197.

An emergency or retainer bearing 215 is provided within the magnetic bearing, which runs empty during normal operation of the vacuum pump 111 without contact and only comes into engagement with an excessive radial deflection of the rotor 149 relative to the stator to create a radial stop for the rotor 149 to form, since a collision of the rotor-side structures with the stator-side structures is prevented. The backup bearing 215 is designed as an unlubricated roller bearing and forms a radial gap with the rotor 149 and / or the stator, which has the effect that the backup bearing 215 is disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 engages is dimensioned large enough that the backup bearing 215 does not come into engagement during normal operation of the vacuum pump, and at the same time small enough that a collision of the rotor-side structures with the stator-side structures under all circumstances is prevented.

The vacuum pump 111 comprises the electric motor 125 for rotatingly driving the rotor 149. The armature of the electric motor 125 is formed by the rotor 149, the rotor shaft 153 of which extends through the motor stator 217. A permanent magnet arrangement can be arranged radially on the outside or embedded on 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 that extends through the motor stator 217, an intermediate space 219 is arranged, which comprises a radial motor gap over which the motor stator 217 and the permanent magnet arrangement for transmitting the drive torque can influence each other magnetically.

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 a flushing gas and which can be air or nitrogen, for example, can enter the engine 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 engine compartment 137 can also be evacuated via the pump outlet 117, i.e. the vacuum pressure produced by the backing pump connected to the pump outlet 117 is at least approximately in the engine compartment 137.

A so-called and known labyrinth seal 223 can also be provided between the rotor hub 161 and a wall 221 delimiting the engine compartment 137, in particular to achieve better sealing of the motor compartment 217 from the Holweck pump stages located radially outside.

In the Figs. 1 to 5 a so-called single-flow pump is described, i.e. one with only one inlet. The vacuum pump described above is therefore not itself designed according to the invention, but can advantageously be developed further within the meaning of the invention. Conversely, all of the embodiments of the invention described herein - insofar as it is technically sensible - by individual or multiple features of the vacuum pump Figs. 1 to 5 be trained.

In Fig. 6 An exemplary vacuum system 10 according to the invention is shown, which has a plurality of vacuum chambers which are evacuated by means of a vacuum pump 12. Specifically, a first vacuum chamber 14, a second vacuum chamber 16 and a third vacuum chamber 18 are provided, each of which is connected to at least one inlet of the vacuum pump 12. A first entry 20 and a second inlet 22 of the vacuum pump 12 are connected to the first chamber 14. A third inlet 24 and a fourth inlet 26 are connected to the second vacuum chamber 16 and the third vacuum chamber 18, respectively.

In this exemplary embodiment, the vacuum pump 12 thus has four inlets. The gas pumped out of the chambers 14, 16, 18 via the inlets 20, 22, 24, 26 is conveyed by the vacuum pump 12 to a common outlet (not shown).

The vacuum pump 12 comprises several pump stages, namely a first pump stage 28, a second pump stage 30, a third pump stage 32 and a fourth pump stage 34. In this example, the first, second and third pump stages 28, 30, 32 are designed as turbo-molecular pump stages . Turbo rotor disks 36 are indicated by vertical lines. In particular, each turbo rotor disk 36 is followed by a turbostator disk (not shown). In this example, the pump stages 28, 30 and 32 each have three sets of turbo rotor and turbo stator disks. In general, the turbo rotor and turbo stator disks can correspond to those of the vacuum pump, for example Figs. 1 to 5 be trained. The turbo rotor disks 36 are all arranged on a common rotor 38 and rotate synchronously when in operation.

The fourth pump stage 34 is designed as a Holweck pump stage. It also comprises a rotor element arranged on the common rotor 38, namely a Holweck rotor sleeve, for example one as in FIG Figures 3 to 5 .

The inlets 20, 22, 24, 26 are each connected to the upstream ends of an associated pump stage, with all pump stages 28, 30, 32, 34 delivering from the inlets to a common outlet, not shown. The first inlet 20 is connected to an upstream end of the first pumping stage 28, while the second inlet 22 is connected to an upstream end End of the second pumping stage 30 is connected. Both inlets 20 and 22 are connected to one and the same vacuum chamber, namely the vacuum chamber 14. Unlike between the inlets 22 and 24 or 24 and 26, no wall or the like is provided between the inlets 20 and 22.

The vacuum chambers 14, 16 and 18 are separated from their respective neighbors by a wall 40, although a small screen 42 is provided in the wall 40. A very limited amount of gas can flow through the small orifice 42 from one chamber of higher pressure to an adjacent chamber of lower pressure. In the present case, the pressure in the third vacuum chamber 18 is greatest, the pressure in the second vacuum chamber 16 is somewhat lower and the pressure in the first vacuum chamber 14 is the lowest. As a result, the gas flows through the diaphragms 42 from the third vacuum chamber 18 into the second vacuum chamber 16 and from there into the first vacuum chamber 14. A largely homogeneous pressure prevails in this chamber.

The first pump stage 28 and the second pump stage 30 are axially adjacent and arranged one after the other in the pumping direction. A steering element 44 is provided between a downstream end of the first pump stage 28 and the second inlet 22. This is designed here essentially as a radially aligned plate which is connected to a housing 46 of the pump. The steering element 44 essentially forms a seal between the downstream end of the first pump stage 28 and the second inlet 22 and vice versa.

The steering element 44 includes an opening 48 through which the common rotor 38 extends. A radial gap must remain between the rotor 38 and the steering element 44, since the rotor 38 rotates at high speed and certain rotor deflections cannot be avoided. Nevertheless, the radial gap is so small that a seal is largely guaranteed. For example, a pump-active structure can be provided in the radial gap in order to even better avoid or reduce leakage from the downstream end of the first pump stage 28 through the opening 48 to the second inlet 22.

Furthermore, a channel 50 is provided which adjoins the steering element 44 and connects the downstream end of the first pump stage 28 to an upstream end of the second pump stage 30, however the inlet 22 is essentially bypassed. For this purpose, the channel 50 leads directly to a first turbo-rotor disk 36 of the second pump stage 30. The volume flows from the inlet 22 and from the channel 50 or from the first pump stage 28 therefore essentially only combine in the second pump stage 30.

Another vacuum system 10 is shown in FIG Fig. 7 shown. This comprises a single, first chamber 14 which is connected to a first inlet 20 and to a second inlet 22 of a vacuum pump 12. The vacuum pump 12 comprises a first pumping stage 28, the upstream end of which is connected to the first inlet 20, and a second pumping stage 30, the upstream end of which is connected to the second inlet 22. Further pump stages can be provided downstream of the second pump stage 30, as is the case, for example, in the embodiment of FIG Fig. 6 the case is.

Similar to the embodiment of Fig. 7 a steering element 44 and a channel 50 are provided in order to guide the gas from the first inlet 20 and the first pump stage 28, bypassing the second inlet 22, to the second pump stage 30. The channel 50 is connected to the steering element 44, in particular formed in one piece thereon. Steering element 44 and channel 50 are arranged in a pump chamber 51 defined by the housing.

In Fig. 8 a steering element 44 with channel 50 is shown in a view transverse to the rotor axis 32. The steering element 44 is correspondingly provided by a housing 46 defined, cylindrical pump chamber 51 with its outer circumference is essentially circular.

A section of the circular surface of the guide element 44 is taken up by the channel 50, which extends axially in a substantially cylindrical manner. In the present example, the channel 50 occupies an angular range of the circular steering element of approximately 120 °, this angular range being arranged opposite the second inlet 22 with respect to the rotor axis 32. In principle, the cross section of the channel can be designed, for example, as a pitch circle, as shown.

In Fig. 9 a vacuum pump 12 with a first inlet 20 and a second inlet 22 for connection to a common vacuum chamber, which is not shown here, is shown. Here and below, only vacuum pumps 12 according to some embodiments are described, a second pumping stage and structures upstream of the same being described in each case. In principle, however, further pump stages, further inlets and / or a different number of vacuum chambers can also be provided, for example as shown in FIG Fig. 6 is described.

The vacuum pump 12 of the Fig. 9 comprises a first pumping stage 28 connected to the first inlet 20 and a second pumping stage 30 connected to the second inlet 22. While in the Figures 6 to 8 only pump stages with three pairs of turbo rotor and turbo stator disks are shown, in the present case the first pump stage 28 has only two pairs of turbo rotor and turbo stator disks, of which only the turbo rotor disks 36 are indicated. The second pumping stage 30 has three pairs of turbo rotor and turbo stator disks, but an upstream turbo rotor disk 52 being designed as a stepped rotor disk. This means that the turbo rotor disk 52 has a first axial section 54 on the upstream side and a first axial section second axial section 56 on the downstream side, wherein the sections have a different active pumping cross-section. Specifically, the diameter of the turbo rotor disk 52 in the first axial section 54 is smaller here than in the second axial section 56.

The vacuum pump 12 of the Fig. 9 comprises a channel 50 through which a downstream end of the first pump stage 28 is connected to the second axial section 56, the channel 50 extending axially past the first axial section 54. Should gas particles conveyed escape radially between the channel 50 and the second axial section 56, some of these particles will be captured by the first axial section 54 of the turbo rotor disk 52 and this particle will be given a new impulse in the direction of the pump outlet. The arrangement shown therefore improves the seal between the downstream end of the first pump stage 28 and the inlet 22 and the pumping speed is further increased.

A similar effect is achieved by the second pump stage 30 in FIG Fig. 10 vacuum pump 12 shown. Here, however, this effect is not obtained via a stepped turbo rotor disk 52, but a separate turbo rotor disk 58 with a smaller diameter is arranged upstream of that turbo rotor disk 36 to which the channel 50 leads.

Another special feature of the embodiment of the Fig. 10 is the axially arranged first inlet 20. The second inlet 22, however, is arranged radially, as is also the case with all in the Figures 6 to 9 shown inlets is the case. The axial inlet 20 brings about a particularly good conductance between the chamber and the first pump stage 28.

Fig. 11 illustrates an embodiment in which a first pump stage 28 has a smaller rotor diameter than a second pump stage 30. Included A first inlet 20 and a second inlet 22 can be arranged axially as indicated. In the present embodiment, the second inlet 22 encloses the first inlet 20 and / or the second pump stage 28. The axial inlets 20 and 22 enable a particularly good conductance for the respective pump stage 28 and 30, respectively.

Another optional feature of the embodiment of the Fig. 11 is that a channel 50 is arranged concentrically to the rotor 38. Specifically, the channel 50 encloses the rotor 38 or the rotor 38 extends axially through the channel 50. The channel 50 is essentially formed by a tubular element. The channel 50 leads from a central region of the downstream end of the first pump stage 28 to a central region of the upstream end of the second pump stage 30.

In Fig. 12 a further embodiment with pump stages 28, 30 of different sizes is shown. In addition, the inlets 20 and 22 are also arranged axially here. In this embodiment, a downstream end of the first pump stage 28 lies directly against an upstream end of the second pump stage 30, specifically in an area which is separated from the second inlet 22, here implemented by a housing 46. The embodiment shown therefore manages without an additional guide element 44 and without an additional channel 50. It also has a short overall axial length.

In Fig. 13 a further embodiment is shown with pump stages 28 and 30 of different sizes, with both inlets 20, 22 again being formed axially.

The second pump stage 30 has a stepped turbo rotor disk 52 on the upstream side, but here different from FIG Fig. 9 the first axial section 54 in the flow direction is not formed centrally but circumferentially, so the Turbo rotor disk 52 essentially has a central recess. The first pumping stage 28 extends with the housing 46 at least in regions past the first axial section 54 or into the central recess of the turbo rotor disk 52 and towards an upstream end of the turbo rotor disk 52 in the corresponding radial region. Similar to in Fig. 9 By means of the arrangement shown, particles which flow out radially from the first pump stage 28 between the housing 46 and the second axial section 56 or the turbo rotor disk 52 are captured by the first axial section 54 of the turbo rotor disk 52. This also further improves the pumping speed.

The embodiments of the Figures 14 and 15 are distinguished, among other things, by the fact that the inlets 20 and 22 are arranged concentrically and / or at the same axial height. In Fig. 15 the rotor diameters of the steps 28 and 30 are essentially the same size, in particular the inlet 22 being formed by a stepped housing section.

the Fig. 16 and 17th show those of the Fig. 6 Similar embodiments, but in a greater degree of detail. In particular, it is illustrated that the steering element 44 can extend into a recess in the shaft, in particular in order to realize a particularly long sealing length for the gap 48. The channels 50 can also, as shown, be of different sizes. The channel 50 is designed statically here. In principle, a channel can also be designed to rotate with the rotor.

The second aspect is in the Fig. 18 and 19th explained in more detail. The pump here comprises channels 60, 62 which together form a channel which connects the downstream end of the first pump stage 28 to a location which is located downstream of at least one rotor element of the second pump stage which is first in the flow direction. In Fig. 18 the channel 60, 62 leads to the downstream end of the second pumping stage 30. In Fig. 19 the channel 60, 62 leads axially behind or to a location downstream of a first pair of rotor and stator disks.

The channels 62 are designed here as a plurality of axial grooves distributed over the circumference of the rotor shaft. The channel 60 is designed as an annular channel and concentric to the rotor shaft. The steering element has passage openings 64 radially inside the channel 60.

the Figures 16-19 also show features related to the Figs. 1 to 5 are described in more detail and are advantageous individually and in combination.

List of reference symbols

111

Turbo molecular pump

113

Inlet flange

115

Pump inlet

117

Pump outlet

119

casing

121

Lower part

123

Electronics 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

Axis of rotation

153

Rotor shaft

155

Rotor disk

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

Connection channel

181

roller bearing

183

Permanent magnet bearings

185

Injection nut

187

disc

189

mission

191

bearing half on the rotor side

193

stator-side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Beam section

203

Beam section

205

radial strut

207

Cover element

209

Support ring

211

Fastening ring

213

Disc spring

215

Emergency or fishing camp

217

Motor stator

219

Space

221

Wall

223

Labyrinth seal

10

Vacuum system

12th

Vacuum pump

14th

first vacuum chamber

16

second vacuum chamber

18th

third vacuum chamber

20th

first admission

22nd

second inlet

24

third inlet

26th

fourth inlet

28

first pumping stage

30th

second pumping stage

32

third pumping stage

34

fourth pumping stage

36

Turbo rotor disk

38

rotor

40

Wall

42

cover

44

Steering element

46

casing

48

opening

50

channel

51

Pumping room

52

stepped turbo rotor disc

54

first axial section

56

second axial section

58

small turbo rotor disk

60

channel

62

channel

64

Passage opening

Claims (15)

1. A vacuum system (10) comprising a vacuum pump (12), in particular a turbomolecular pump, and at least one vacuum chamber (14),
   wherein the vacuum pump (12) comprises:

   at least a first and a second inlet (20, 22) and a common outlet; and

   at least a first and a second pump stage (28, 30), which each have at least one rotor element (36) which is arranged on a common rotor (38), wherein the first inlet (20) is connected to an upstream-side end of the first pump stage (28) and the second inlet (22) is connected to an upstream-side end of the second pump stage (30),

   wherein the first inlet (20) and the second inlet (22) are connected to the same vacuum chamber (14),

   characterized in that the downstream-side end of the first pump stage (28) is connected to the upstream-side end of the second pump stage (30) while bypassing the second inlet (22).
2. A vacuum system (10) in accordance with claim 1,
   wherein a steering element (44) is provided for preventing a gas flow from the downstream-side end of the first pump stage (28) toward the second inlet (22).
3. A vacuum system (10) in accordance with claim 1 or claim 2,
   wherein the downstream-side end of the first pump stage (28) is connected to the upstream-side end of the second pump stage (30) by a channel (50).
4. A vacuum system (10) in accordance with claim 3,
   wherein the channel (50) is eccentrically arranged with respect to the rotor (38), wherein in particular the rotor (38) is arranged outside the channel (50).
5. A vacuum system (10) in accordance with claim 3,
   wherein the channel (50) is arranged concentrically with respect to the rotor (38) and/or surrounds the rotor (38).
6. A vacuum system (10) in accordance with any one of the claims 3 to 5,
   wherein the channel (50) is arranged disposed opposite the second inlet (22) with respect to the rotor (38).
7. A vacuum system (10) in accordance with any one of the claims 3 to 6,
   wherein the pump (12) comprises a housing (46) which defines a pump space (51) in which the rotor elements (36) of the pump stages (28, 30) are arranged, wherein the channel (50) is arranged in the pump space (51).
8. A vacuum system (10) in accordance with any one of the preceding claims,
   wherein the second pump stage (30) has a turbo-rotor disk (52) at its upstream-side end, said turbo-rotor disk (52) having a first axial section (54) arranged upstream and a second axial section (56) arranged downstream of the first axial section (54), wherein the rotor disk (52) has a smaller pump-active cross-section in the first axial section (54) than in the second axial section (56), wherein the downstream-side end of the first pump stage (28) is connected to the second axial section (56) while at least regionally bypassing the first axial section (54).
9. A vacuum system (10) in accordance with any one of the preceding claims,
   wherein the second pump stage (30) has at least two turbo-rotor disks (36, 58), wherein a first rotor disk (58) arranged upstream has a smaller pump-active diameter than a second rotor disk (36) arranged downstream of the first rotor disk (58), wherein the downstream-side end of the first pump stage (28) is connected to the second rotor disk (36) while at least regionally bypassing the first rotor disk (58).
10. A vacuum system (10) in accordance with any one of the preceding claims,
    wherein the second pump stage (30) has a larger rotor diameter than the first pump stage (28).
11. A vacuum system (10) in accordance with any one of the preceding claims,
    wherein the first and/or the second inlet (20, 22) is/are a radial inlet and/or an axial inlet.
12. A vacuum system (10) in accordance with any one of the preceding claims,
    wherein the second inlet (22) is an axial inlet and is disposed radially beyond the first pump stage (28).
13. A vacuum system (10) in accordance with any one of the preceding claims,
    wherein a first rotor element (36) and an adjacent second rotor element (36) arranged downstream of the first rotor element (36) are provided in the first and/or second pump stage (28, 30), wherein the second rotor element (36) has a smaller suction capacity than the first rotor element (36), and/or wherein the second rotor element (36) has a larger compression than the first rotor element (36).
14. A vacuum system (10) in accordance with any one of the preceding claims,
    wherein the second pump stage (28) has, at the upstream side, at least two rotor elements (36) having substantially the same suction capacity.
15. Use of a vacuum pump (12), in particular a turbomolecular pump, for evacuating at least one vacuum chamber (14),
    wherein the vacuum pump (12) comprises:

    at least a first and a second inlet (20, 22) and a common outlet; and

    at least a first and a second pump stage (28, 30) which each have at least one rotor element (36) which is arranged on a common rotor (38), wherein the first inlet (20) is connected to an upstream-side end of the first pump stage (28) and the second inlet (22) is connected to an upstream-side end of the second pump stage (30),

    wherein the first inlet (20) and the second inlet (22) are connected to the same vacuum chamber (14),
    characterized in that the downstream-side end of the first pump stage (28) is connected to the upstream-side end of the second pump stage (30) while bypassing the second inlet (22).

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