EP3267040B1 - Turbomolecular pump - Google Patents

Description

The present invention relates to a turbomolecular pump with a pump inlet and a pump outlet, which are formed in a common pump housing, and with at least one turbomolecular pump stage, which has an inlet region associated with the pump inlet and an outlet region.

Vacuum pumps play an important role in vacuum technology and are used in a wide variety of technical applications for suction of mostly gaseous media and for the evacuation of cavities. Among other things, turbomolecular pumps, also known as turbopumps, are used. Turbomolecular pumps work in the molecular, i.e. non-viscous, range and are suitable for generating a vacuum with a very high level of purity.

A turbomolecular pump typically includes a housing that encloses a pump chamber with a rotor shaft. At least one pump structure of the turbomolecular pump is arranged in the pump room, which conveys a gas present in the pump room or in an area to be evacuated from an inlet to an outlet of the turbomolecular pump and thereby pumps it. A drive for the rotor shaft is usually arranged in a storage room that is separate from the pump room.

Turbomolecular pumps are torque transfer pumps in which gas molecules entering the pump of a gas to be pumped receive a torque through an impact on the moving rotor blades of the rotor shaft. The Pump usually contains several pump stages of rotor and stator disks arranged in series or one behind the other. Each pump stage generally consists of at least one rotor and stator disk, which are arranged in pairs. If necessary, a pump stage can also consist of only one rotor disk, and this applies in particular to the pump stage located at the downstream end. In this case, the pump ends with a rotor disk. In addition to the torque, the gas molecules receive a movement component parallel to the axis of the pump due to the position of the rotor and stator disks relative to one another, the axis usually corresponding to the rotor shaft. Generally, multiple pump stages increase the pressure of the gas from the inlet to the outlet of the pump.

A turbomolecular pump basically only works effectively in pressure ranges in the molecular flow range and does not evacuate or deliver to atmospheric pressure, but is usually supported by a backing pump, which then ejects against a gas pressure of more than 1 mbar. The working pressure range of the turbomolecular pump can be expanded by coupling a molecular pump stage driven by the same rotor shaft, for example a Holweck pump stage or Siegbahn pump stage, to the outlet of the turbomolecular pump within the pump housing. This makes it possible to use backing pumps with lower performance because the outlet pressure of the gas is increased.

Backing pumps, for example diaphragm pumps and spiral or scroll pumps, are self-sufficient pumps that are arranged separately from the turbomolecular pump in question, the suction side of which is connected to the outlet of the turbomolecular pump via lines. For the user, such an arrangement involves a certain amount of effort in terms of an airtight and electrical connection of both pumps. A risk of functional impairment due to leaks and errors in the electrical connection cannot generally be ruled out.

Known from the prior art are so-called pumping stations, in which a turbomolecular pump and a fore-vacuum pump are mounted on a common frame and are already airtight and electrically connected by the manufacturer. However, such arrangements are usually relatively large and therefore require a lot of space. Furthermore, they are often limited in terms of their installation position and are therefore difficult to integrate into existing systems.

From the EP 2 644 893 A2 a turbomolecular pump according to the preamble of claim 1 is known.

Furthermore, it is also from the DE 698 15 806 T2 a turbomolecular pump according to the preamble of claim 1 is known.

The EP 1 213 482 A1 shows a turbomolecular pump according to a related technology.

Reference is also made to the state of the art DE 601 01 368 T2 as well as EP 2 631 488 A1 .

The object of the present invention is to provide a turbomolecular pump which overcomes the disadvantages described above, i.e. a compact, easy-to-integrate turbomolecular pump, the commissioning of which is as simple as possible and therefore has few sources of error, while at the same time the turbomolecular pump can be produced with as little effort as possible and also a should have a long service life.

The problem is solved according to the invention by a turbomolecular pump with the features of claim 1. The turbomolecular pump according to the invention comprises at least one pre-pump stage effective between the outlet region of the turbomolecular pump stage and the pump outlet, which is designed to compress gas conveyed by the turbomolecular pump stage and to expel it against a gas pressure of more than 1 mbar, in particular against atmospheric pressure.

The turbomolecular pump according to the invention is characterized in particular by the integration of the pre-pumping stage.

The turbomolecular pump according to the invention is therefore particularly advantageously a compact unit that can be put into operation immediately without having to connect a separate backing pump as a further component. For the user, this results in significant time savings during installation and space savings. The risk of errors occurring during installation is greatly reduced due to the integral design. In other words, the pump according to the invention can be handled like a conventional pump of the respective type, especially with regard to the minimal space requirement and the arbitrary installation position. The pump has its own pre-pump stage, so to speak, "on board", so that it can also generate a high vacuum pressure on the suction side and, on the discharge side, directly against a relatively high pressure and in particular against atmospheric pressure, while at least largely retaining all the advantages of a conventional pump of the respective type can eject.

The invention can be realized in particular by using a special small design of a pump type suitable as a pre-pumping stage. In this context, one can also speak of miniaturized pre-pump stages or simply “mini pre-pumps”. Such backing pumps can work in continuous operation without their own backing pumps and can eject against a relatively high pressure, for example of more than 1 mbar, or even against atmospheric pressure. It has Surprisingly, it has been shown that such pumps can be used as backing pumps integrated into turbomolecular pumps and can therefore make the use of conventional backing pumps unnecessary. A lot of energy can be saved by eliminating a separate backing pump.

In some applications, a conventional separate backing pump can be helpful for initially evacuating a recipient. In actual continuous operation, however, the integrated pre-pump stage according to the invention is sufficient, i.e. the conventional separate pre-pump then only needs to be used for the initial evacuation, for example by temporarily connecting in parallel.

The pre-pumping stage is based on a type of pump drive movement that is different from that of the turbomolecular pumping stage. The pre-pumping stage develops its pumping effect through components that orbit relative to one another during operation. In other words, the pre-pumping stage is based on an orbiting relative movement of its pumping components.

In comparison to turbomolecular pump stages or molecular pump stages, the pumping effect of which is fundamentally based on components that rotate relative to one another during operation, the pre-pump stage is based on an orbiting relative movement of its pumping components. Surprisingly, it has been found that the vibrations caused by the different pump drive movements of the turbomolecular pump stage and pre-pump stage can at least partially cancel each other out. Overall, in this way - as a side effect, so to speak - a turbomolecular pump with at least less vibration can be realized.

The pump stage comprises at least one stationary conveying element and at least one conveying element that moves during operation relative to the stationary conveying element, wherein the stationary delivery element of the pre-pumping stage is at least partially formed by the pump housing. The stationary conveying element is, for example, a spiral-shaped stator of a spiral vacuum pump or scroll vacuum pump.

Furthermore, the pre-pumping stage can have at least one axis of movement, with respect to which at least two components of the pre-pumping stage move relative to one another during operation, the axis of movement of the pre-pumping stage and a rotation axis of a rotor shaft of the turbomolecular pumping stage not coinciding. Alternatively or additionally, the pre-pumping stage can have at least one axis of symmetry that does not coincide with the axis of rotation of the rotor shaft of the turbomolecular pumping stage. For example, the two components are the spiral rotor and the spiral stator of a spiral or scroll vacuum pump.

According to a preferred embodiment, the pre-pump stage is a dependent unit, the operation of which requires one or more functional parts of the turbomolecular pump. Alternatively or additionally, a common control and/or a common energy supply can be provided for the turbomolecular pump stage and for the pre-pump stage.

The functional parts of the turbomolecular pump can be, for example, an electric motor, an accessory connection, a data interface, a flood inlet, a barrier or coolant connection, a rotor shaft or structural elements forming gas flow paths. The pre-pumping stage is preferably dependent on the energy supply of the turbomolecular pumping stage and possibly further pumping stages and shares a common control with this pumping stage or these pumping stages.

According to a further embodiment, the pre-pump stage is of the type of a spiral or scroll vacuum pump.

Spiral or scroll vacuum pumps usually have crescent-shaped scoop spaces, which are formed by a rotor with a spiral cross-section in engagement with a similar spiral-shaped stator, the rotor being set into an orbiting movement by an eccentric drive. This type of pump is therefore based on an orbiting pump drive movement.

The priming stage is of a type different from a side channel or regeneration vacuum pump.

In the side channel pump, power is transferred from a rotor rotating concentrically in the housing to a medium to be pumped in a side channel arranged next to the rotor. During circulation, the medium moves back and forth several times between individual areas of the rotor and the side channel. Through momentum exchange, energy is transferred between the medium, which rotates at approximately the rotational speed of the rotor, and the medium, which flows more slowly in the side channel. The delivery performance is based on this exchange of impulses. This type of pump is therefore based on a rotating pump drive movement.

It has been found that the pump types mentioned above as further developments of the invention are particularly suitable for integration according to the invention into a turbomolecular pump.

Preferably, the pre-pumping stage is integrated into the turbomolecular pump completely independently of the position of the rotor shaft of the turbomolecular pumping stage. This can in particular simplify retrofitting existing turbomolecular pumps with an integrated pre-pump stage. For example, it may be sufficient to modify only a few components, e.g. the housing, of an existing turbomolecular pump in order to integrate a pre-pump stage.

The pre-pump stage comprises a housing which is at least partially formed by the pump housing.

Preferably, at least one, preferably three, in particular five housing side(s) of the housing of the pre-pump stage is/are at least partially formed by the pump housing. For this purpose, the housing of the pre-pump stage can, for example, be placed on the pump housing with one open housing side or inserted or pushed into a corresponding receptacle of the pump housing with several open housing sides.

The pre-pump stage can also be at least partially enclosed by a housing within the pump housing, in particular in order to achieve a demarcation from further functional parts of the turbomolecular pump stage.

The housing of the pre-pump stage can be connected to the pump housing by fasteners such as screws, rivets or adhesive.

According to one embodiment, the pre-pumping stage or at least one pump-active structure of the pre-pumping stage is arranged in the pump housing or on the pump housing.

Particularly preferably, the pre-pumping stage is arranged in the pump housing or within the pump housing, ie the pre-pumping stage is preferably completely surrounded by the pump housing. In this way, additional fastening means between the pump housing and a housing of the pre-pump stage are eliminated. Furthermore, this increases the compactness or the functional density of the turbomolecular pump, since there are no additional protruding or projecting surfaces Approaches are present on an outer surface of the pump housing. This also ensures improved handling and easier installation of the turbomolecular pump.

In addition to the pump-active structure of the fore-vacuum pump, such as two meshing spiral-shaped conveying elements of a spiral or scroll vacuum pump, an optional drive of the fore-pump stage can also be arranged in or on the pump housing.

According to a further embodiment, the pre-pumping stage or at least a pump-active structure of the pre-pumping stage is at least partially formed by the pump housing.

For example, the spiral stator of a spiral or scroll vacuum pump can be designed as an integral part of the pump housing.

According to a further embodiment, the pre-pump stage is many times smaller than the pump housing, at least 5 to 10 times, preferably 10 to 15 times. The pre-pumping stage preferably only takes up about a fifth to a tenth, in particular a tenth to a fifteenth, of the total volume of the pump housing.

According to one embodiment, the pre-pump stage is arranged asymmetrically and/or eccentrically with respect to the axis of rotation of the rotor shaft of the turbomolecular pump stage. In particular, the arrangement of the pre-pump stage is independent of the position of the rotor shaft of the turbomolecular pump stage.

The pre-pumping stage can be arranged within a limited angular range around the axis of rotation of the rotor shaft of the turbomolecular pumping stage, whereby the Angular range is less than 180°, in particular less than 135°, preferably less than 90°.

According to a further embodiment, an outlet region of the pre-pumping stage forms the pump outlet. Alternatively, the outlet region of the pre-pump stage may be connected to the pump outlet directly or via a gas flow path that is delimited by one or more housing parts and/or stationary, fixed structural elements located within the pump housing.

The gas flow path is, for example, a channel which is formed in particular in a wall of the pump housing.

Preferably, the inlet region of the pre-pump stage is connected directly to the outlet region of the turbomolecular pump stage or to an outlet region of a further pump stage arranged between the turbo-molecular pump stage and the pre-pump stage.

The further pump stage is in particular a molecular pump stage, for example a Siegbahn and/or Holweck pump stage. Several further pump stages can be arranged between the turbomolecular pump stage and the pre-pump stage.

Furthermore, it can be provided that a gas flow path between the outlet region of the turbomolecular pump or the outlet region of the further pump stage arranged between the turbomolecular pump stage and the pre-pump stage on the one hand and the inlet region of the pre-pump stage on the other hand by one or more housing parts and / or stationary, fixed ones within the pump housing structural elements located is limited.

A preferred embodiment of the turbomolecular pump according to the invention has a turbomolecular pump stage, a molecular pump stage, in particular a Holweck pump stage, and a pre-pump stage. The pre-pump stage is a miniaturized spiral or scroll vacuum pump compared to the dimensions of the pump housing of the turbomolecular pump, the spiral-shaped stator of which is formed by a structural element of the pump housing. The spiral or scroll vacuum pump preferably has its own electric motor drive, which draws its energy from the energy supply of the turbomolecular pump stage and/or the molecular pump stage. The spiral or scroll vacuum pump including its drive motor is arranged in the pump housing and the outlet area of the spiral or scroll vacuum pump is connected to the pump outlet via a gas flow path, which is in particular designed as a simple bore.

Preferably, the external dimensions of a turbomolecular pump according to the invention are at least essentially the same as the dimensions of a corresponding conventional turbomolecular pump which does not include an integrated pre-pump stage.

The inventive integration of the pre-pump stage into the turbomolecular pump significantly increases the compactness of a high vacuum pump system, which previously usually consisted of at least two separate components - the turbomolecular pump and the fore-vacuum pump. This significantly reduces the space requirement. Installation is particularly simplified for the user because there is no need to wire two separate components. The short gas flow paths within the turbomolecular pump housing created by integrating the pre-pump stage also reduce the risk of leaks.

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

eine schematische Längsschnittansicht einer erfindungsgemäßen Turbomolekularpumpe,

Fig. 7

eine schematische Querschnittsansicht der Turbomolekularpumpe von Fig. 6 und,

Fig. 8-11

verschiedene Ausführungsformen einer erfindungsgemäßen Turbomolekularpumpe.

The invention is described below by way of example using advantageous embodiments with reference to the attached figures. Show it:

Fig. 1

a perspective view of a turbomolecular pump,

Fig. 2

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

Fig. 3

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

Fig. 4

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

Fig. 5

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

Fig. 6

a schematic longitudinal section view of a turbomolecular pump according to the invention,

Fig. 7

a schematic cross-sectional view of the turbomolecular pump of Fig. 6 and,

Fig. 8-11

various embodiments of a turbomolecular pump according to the invention.

In the Fig. 1 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 backing pump, such as a rotary vane pump, can be connected.

The inlet flange 113 forms the alignment of the vacuum pump 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 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 (cf. Fig. 3 ). Several connections 127 for accessories are provided on the electronics housing 123. In addition, a data interface 129, for example according to 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 turbomolecular pump 111, via which the vacuum pump 111 can be ventilated. In the area of the lower part 121 there is also a sealing gas connection 135, which is also referred to as a flushing gas connection, via which flushing gas to protect the electric motor 125 from the gas delivered by the pump into the engine compartment 137, in which the electric motor 125 in the vacuum pump 111 accommodated, can be brought (cf. Fig. 3 ). Two coolant connections 139 are also arranged in the lower part 121, one of the coolant connections being provided as an inlet and the other coolant connection as an outlet for coolant, which can be passed through 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 underside 141. The vacuum pump 111 can also be attached to a recipient via the inlet flange 113 and can therefore be operated hanging, so to speak. In addition, the vacuum pump 111 can be designed so that it is also in operation can be taken if it is oriented in a different way than in Fig. 1 is shown. Embodiments of the vacuum pump can also be implemented in which the underside 141 can be arranged not facing downwards, but facing to the side or facing upwards.

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

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

In the Fig. 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 Fig. 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 which can be rotated about a rotation axis 151.

The turbomolecular pump 111 comprises a plurality of turbomolecular pump stages connected in series with one another and having a plurality of 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 pump stage. Together, the pairs form rotor disk 155 and stator disk 157, a turbomolecular pump stage 250. The stator disks 157 are held at a desired axial distance from one another by spacer rings 159.

The vacuum pump also includes Holweck pump stages that are arranged one inside the other in the radial direction and are effectively connected in series. The rotor of the Holweck pump stages includes a rotor hub 161 arranged on the rotor shaft 153 and two cylindrical 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 axis of rotation 151 and nested in one another in the radial direction. Furthermore, two cylindrical jacket-shaped Holweck stator sleeves 167, 169 are provided, which are also oriented coaxially to the axis of rotation 151 and are nested within one another when viewed 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 lies opposite the radial outer surface of the outer Holweck rotor sleeve 163, forming a radial Holweck gap 171 and with this forms the first Holweck pump stage following the turbomolecular pumps. The radial inner surface of the outer Holweck rotor sleeve 163 faces the radial outer surface of the inner Holweck stator sleeve 169 to form a radial Holweck gap 173 and forms a second Holweck pump stage with this. 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 with this forms the third Holweck pump stage.

At the lower end of the Holweck rotor sleeve 163, a radially extending channel can be provided, via which the radially outer Holweck gap 171 communicates with the middle Holweck gap 173 is connected. 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. This means that the nested Holweck pump stages are connected in series with one another. At the lower end of the radially inner Holweck rotor sleeve 165, a connecting channel 179 to the outlet 117 can also be provided.

The above-mentioned 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 is used to operate the Drive vacuum pump 111 into the Holweck grooves.

To rotatably support the rotor shaft 153, a rolling bearing 181 is provided in the area of the pump outlet 117 and a permanent magnet bearing 183 in the area of the pump inlet 115.

In the area of the rolling bearing 181, a conical injection nut 185 with an outer diameter increasing towards the rolling bearing 181 is provided on the rotor shaft 153. The injection nut 185 is in sliding contact with at least one wiper of an operating medium storage. The operating medium storage comprises several absorbent disks 187 stacked on top of one another, which are soaked with an operating medium for the rolling bearing 181, for example with a lubricant.

During operation of the vacuum pump 111, the operating fluid is transferred by capillary action from the operating fluid storage via the wiper 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 rolling bearing 181, where it e.g. fulfills a lubricating function.

The rolling bearing 181 and the operating fluid storage 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 comprises a ring stack made up of a plurality of 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 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 on the radial outside. The stator-side ring magnets 197 are supported by a stator-side support section 203, which extends through the ring magnets 197 and is suspended on 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 203. 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 rests without contact during normal operation of the vacuum pump 111 and only comes into engagement when there is an excessive radial deflection of the rotor 149 relative to the stator in order to create a radial stop for the rotor 149 form, thereby preventing a collision between the rotor-side structures and the stator-side structures becomes. The backup bearing 215 is designed as an unlubricated rolling bearing and forms a radial gap with the rotor 149 and/or the stator, which causes the backup bearing 215 to be disengaged during normal pumping operation. The radial deflection at which the backup bearing 215 comes into engagement is large enough so that the backup bearing 215 does not come into engagement 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 occurs under all circumstances is prevented.

The vacuum pump 111 includes the electric motor 125 for rotating 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 that extends through the motor stator 217. Between the motor stator 217 and the section of the rotor 149 that extends through the motor stator 217, a gap 219 is arranged, which comprises a radial motor gap, via which the motor stator 217 and the permanent magnet arrangement can magnetically influence each other for transmitting the drive torque.

The motor stator 217 is fixed in the housing within the engine compartment 137 provided for the electric motor 125. A sealing gas, which is also referred to as purge gas and which can be, for example, air or nitrogen, can reach the engine compartment 137 via the sealing gas connection 135. The barrier gas can be used to protect the electric motor 125 from process gas, for example from corrosive components of the process gas. The engine compartment 137 can also be evacuated via the pump outlet 117, ie in the engine compartment 137 there is at least approximately the vacuum pressure caused by the backing vacuum pump connected to the pump outlet 117.

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 in order to achieve a better sealing of the engine compartment 217 compared to the Holweck pump stages located radially outside.

Fig. 6 shows schematically a possible basic structure of a turbomolecular pump 110 according to the invention, which has a turbomolecular pump stage 250 arranged in a housing 119, a molecular pump stage 270 connected downstream of it and a pre-pump stage 300 connected downstream of the molecular pump stage 270. The pre-pumping stage 300 has a housing 302, which is partially formed by the housing 119. As can be seen from the representation of the Fig. 6 As becomes clear, the housing 302 of the pre-pumping stage 300 is much smaller than the pump housing 119. The pre-pumping stage 300 is thus integrated into the turbomolecular pump 110.

A gas flow path 312 is indicated by arrows. A gas to be pumped enters the turbomolecular pump stage 250 from a recipient (not shown) via an inlet region 116. After passing through an outlet region 118 of the turbomolecular pumping stage 250, the gas enters the molecular pumping stage 270 and passes from its outlet region 272 into an inlet region 316 of the pre-pumping stage 300. The pre-pumping stage 300 pushes the gas against a comparatively high pressure of more than compared to a vacuum 1 mbar and in particular against atmospheric pressure, namely via an outlet region 310 of the pre-pumping stage 300. It can therefore be the pre-pumping stage 300 that forms the outlet 117 of the pump 110.

Fig. 7 shows a schematic cross section through the turbomolecular pump 110 Fig. 6 , which is shown here as a square for simplicity. Alternatively, the cross section can be circular. It can be seen that the pre-pumping stage 300 is arranged within an angular range of less than 90° about an axis of rotation 151 of a rotor shaft 153. The rotor shaft 153 is both the turbomolecular pump stage 250 and the molecular pump stage 270 are assigned. The arrangement of the pre-pumping stage 300 in the housing 119 is in principle independent of the position of the rotor shaft 153, since the pre-pumping stage 300 is not part of the rotor shaft 153 and is not driven by the rotor shaft 153.

The Fig. 6 and 7 It can be seen that the pre-pumping stage 300 is arranged in a bottom edge region of the pump housing 119.

The Fig. 8 to 10 each show a turbomolecular pump 110 according to the invention, which differs from the pump according to Fig. 1 to 5 each essentially differ by the integrated pre-pump stage 300, the arrangement of the pump outlet 117 and the arrangement of the sealing gas connection 135. Corresponding components are only partially provided with identical reference numbers for reasons of clarity. Matches between the pumps 110 are sometimes only made in connection with one of the Fig. 8 to 10 explained.

The turbomolecular pump 110 according to Fig. 8 includes a molecular pump stage 270 in the form of three Holweck pump stages, which are connected downstream of the turbomolecular pump stage 250. The outlet region 272 of the molecular pump stage 270 is connected to the inlet region of the pre-pump stage 300 via a gas flow path 312, which is designed as a bore in a structural element of the housing 119. The outlet region 310 of the pre-pumping stage 300 forms the pump outlet 117, through which the gas to be pumped can be expelled against atmospheric pressure.

The pre-pumping stage 300 is, for example, an in Fig. 8 Spiral or scroll vacuum pump, not shown, which is surrounded by a housing 302. Parts of the housing 302 are formed by the housing 119. Conversely, the housing 302 of the pre-pumping stage 300 forms part of the actual Pump housing 119. The pre-pump stage 300 can also include another type of pump in a small design.

The pre-pumping stage 300 further comprises its own drive motor, which is arranged within the housing 302 and is connected to the electronics housing 123 and in particular to the power supply connection 131 via a schematically indicated power supply line 124. Pre-pumping stage 300, molecular pumping stage 270 and turbomolecular pumping stage 250 thus share an energy source, i.e. pre-pumping stage 300 is not an independent unit. The pre-pumping stage 300 is therefore not only spatially but also functionally integrated into the turbomolecular pump 110.

Fig. 9 shows a further embodiment of a turbomolecular pump 110 according to the invention, in which the pre-pumping stage 300 is located completely within the pump housing 119. The outlet region 310 of the pre-pumping stage 300 is connected to the pump outlet 117 via a gas flow path 312.

Fig. 10 shows a further embodiment of the turbomolecular pump 110 according to the invention, in which a stationary delivery element 306 of the pre-pump stage 300 is formed by the pump housing 119. The stationary conveying element 306 is a spiral-shaped stator of a spiral or scroll vacuum pump forming the pre-pumping stage 300. The spiral stator can either be milled into the housing 119 or formed on a separate insert that can be inserted into the housing 119 and fixed.

The pre-pumping stage 300 further comprises a moving conveying element 308 in the form of a spiral-shaped rotor, which is driven by an electric motor 318. The rotor 308 and the motor 318 can be inserted into a receiving space of the pump housing 119 to assemble the rotor 308 and stator 306. The rotor 308 and the stator 306 can be formed on one insert be that closes the pump housing 119. Alternatively, a separate closure element can be provided.

The motor 318 is in turn connected to the electronics housing 123 via a line 124. The outlet region 310 of the pre-pumping stage 300 is connected to the pump outlet 117 via a gas flow path 312 in the form of a bore formed in the housing 119.

Fig. 11 shows a further embodiment of a turbomolecular pump 110 according to the invention, in which the pre-pumping stage 300 is located completely within the pump housing 119. The pre-pump stage 300 is a spiral or scroll vacuum pump, which comprises a spiral-shaped stator as a stationary conveying element 306 and a spiral-shaped orbiter as a moving conveying element 308. This conveying element 308 is driven by an electric motor 318 connected to the electronics housing 123 via a line 124. The outlet area of the pre-pump stage 300 is connected to the pump outlet 117 in a manner not shown in detail here.

Reference symbol list

110, 111

Turbomolecular pump

113

inlet flange

115

Pump inlet

116

Inlet area

117

Pump outlet

118

outlet area

119

Housing

121

Bottom part

123

Electronics housing

124

Power supply line

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 disc

157

stator disk

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

rotor side bearing half

193

stator side bearing half

195

Ring magnet

197

Ring magnet

199

Bearing gap

201

Support section

203

Support section

205

radial strut

207

Lid element

209

Support ring

211

Fastening ring

213

Disc spring

215

Emergency or detention camp

217

Motor stator

219

space

221

wall

223

Labyrinth seal

250

Turbomolecular pumping stage

270

pump stage

272

outlet area

300

Pre-pumping stage

302

Housing

304

pump-active structure

306

stationary conveyor element

308

moving conveyor element

310

outlet area

312

Gas flow path

314

Structural element

316

Inlet area

318

Electric motor

Claims (13)

1. A turbomolecular pump (110) comprising

   a pump inlet (115) and a pump outlet (117) which are formed in a common pump housing (119);

   at least one turbomolecular pump stage (250) which has an inlet region (116) associated with the pump inlet (115) and an outlet region (118); and at least one backing pump stage (300) which acts between the outlet region (118) of the turbomolecular pump stage (250) and the pump outlet (117) and which is configured to compress gas conveyed by the turbomolecular pump stage (250) and to expel it against a gas pressure of more than 1 mbar, in particular against atmospheric pressure,

   wherein the backing pump stage (300) is integrated into the turbomolecular pump (110), and

   wherein the backing pump stage (300) is based on an orbiting relative movement of its pump-active components which is different from the pump driving movement of the turbomolecular pump stage (250), characterized in that

   the backing pump stage (300) comprises at least one stationary conveying element (306) and at least one conveying element (308) moving relative to the stationary conveying element (306) during operation, wherein the stationary conveying element (306) of the backing pump stage (300) is at least partly formed by the pump housing (119).
2. A turbomolecular pump (110) according to claim 1, characterized in that the backing pump stage (300) has at least one axis of movement with respect to which at least two components of the backing pump stage (300) move relative to one another during operation, with the axis of movement of the backing pump stage (300) and an axis of rotation (151) of a rotor shaft (153) of the turbomolecular pump stage (250) not coinciding, and/or in that the backing pump stage (300) has at least one axis of symmetry which does not coincide with an axis of rotation (151) of a rotor shaft (153) of the turbomolecular pump stage (250).
3. A turbomolecular pump (110) according to claim 1 or 2, characterized in that the backing pump stage (300) is a dependent unit for whose operation one or more functional parts of the turbomolecular pump (110) are required, and/or in that a common control and/or a common energy supply is/are provided for the turbomolecular pump stage (250) and for the backing pump stage (300).
4. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) is of a spiral or scroll vacuum pump type.
5. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) is of a type that is different from a side channel pump or a regeneration vacuum pump.
6. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) comprises a housing (302) which is at least partly formed by the pump housing (119), and/or in that the backing pump stage (300) or at least one pump-active structure (304) of the backing pump stage (300) is arranged in the pump housing (119) or at the pump housing (119).
7. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) or at least one pump-active structure (304) of the backing pump stage (300) is at least partly formed by the pump housing (119).
8. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) is smaller by a multiple, at least 5 to 10 times smaller, than the pump housing (119).
9. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) is arranged asymmetrically and/or eccentrically with respect to an axis of rotation (151) of a rotor shaft (153) of the turbomolecular pump stage (250).
10. A turbomolecular pump according to any one of the preceding claims, characterized in that the backing pump stage (300) is arranged within a limited angular range about an axis of rotation (151) of a rotor shaft (153) of the turbomolecular pump stage (250), with the angular range being less than 180°, in particular less than 135°, preferably less than 90°.
11. A turbomolecular pump according to any one of the preceding claims, characterized in that an outlet region (310) of the backing pump stage (300) forms the pump outlet (117), or in that the outlet region (310) of the backing pump stage (300) is directly connected to the pump outlet (117) or via a gas flow path (312) which is bounded by one or more housing parts and/or stationary, fixed structural elements (314) located within the pump housing (119).
12. A turbomolecular pump according to any one of the preceding claims, characterized in that an inlet region (316) of the backing pump stage (300) is directly connected to the outlet region (118) of the turbomolecular pump stage (250) or to an outlet region (272) of a further pump stage (270) arranged between the turbomolecular pump stage (250) and the backing pump stage (300).
13. A turbomolecular pump according to any one of the preceding claims, characterized in that a gas flow path (312) between the outlet region (118) of the turbomolecular pump (250) or an outlet region (272) of a further pump stage (270) arranged between the turbomolecular pump stage (250) and the backing pump stage (300), on the one hand, and an inlet region (316) of the backing pump stage (300), on the other hand, is bounded by one or more housing parts and/or stationary, fixed structural elements (314) located within the pump housing (119).

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