EP2772650B1 - Vacuum pump - Google Patents

Description

The invention relates to a vacuum pump, in particular a turbomolecular pump, an arrangement with a vacuum pump, in particular with a turbomolecular pump, and a method for operating a vacuum pump, in particular a turbomolecular pump.

Vacuum pumps are used in various technical processes, for example in semiconductor production, to remove a gas to be pumped, which is also referred to as pumping gas, from a volume to be evacuated and to generate a vacuum necessary for the respective technical process. Particular importance is given to turbomolecular pumps, which are operated at high speeds and are able to produce a vacuum with high purity.

In the operation of the known vacuum pumps occurs significant heating of the vacuum pumps, which deteriorates the pumping properties and performance of the vacuum pump, increases the maintenance of the vacuum pump and reduces their service life. It is known to provide a vacuum pump with a cooling device in order to avoid excessive heating of the vacuum pump.

Known cooling devices, such as, for example, water cooling or air cooling, whose cooling effect is based on the circulation of warm pump components or heat sinks attached thereto with air, are relatively expensive and have a limited effectiveness. In particular, it is difficult with the known cooling devices, areas of the pump, which heat up particularly strong and are arranged for example in the lower part of the pump locally targeted to cool such that set anywhere desired temperature conditions. Thus, excessive heating also occurs in the vacuum pumps cooled in this way, which deteriorates the pumping and performance characteristics of the vacuum pump and decreases the life thereof. The object of the invention is therefore to provide a vacuum pump, an arrangement with a vacuum pump and a method for operating a vacuum pump, which can be achieved with reduced effort an improved pump performance and service life of the vacuum pump and with which in particular an effective and sufficient cooling in all Areas of the vacuum pump is provided so that the vacuum pump is effectively protected everywhere from overheating during operation.

In the JP 2002 039092 A a vacuum pump is described having a pump inlet, a pump outlet and a pump chamber arranged therebetween for a gas to be pumped, which has a cooling gas inlet for a cooling gas for cooling the vacuum pump and a hollow region which is gas-conductively connected to the cooling gas inlet and arranged outside of the pump chamber.

The US 6 019 581 A and WO89 / 06319 Write down similar vacuum pumps.

The object is achieved by a vacuum pump with the features of claim 1.

The vacuum pump, in particular turbomolecular pump, comprises a pump inlet, a pump outlet and a pump space arranged between the pump inlet and the pump outlet for a gas to be pumped. The vacuum pump further comprises at least one cooling gas inlet for a cooling gas for cooling the vacuum pump and one or more gas-conductively connected to the cooling gas inlet and arranged outside the pump chamber hollow areas for the cooling gas, wherein the or each hollow area is limited by at least one component of the vacuum pump.

During the operation of the vacuum pump, cooling gas is admitted directly into the hollow regions arranged in the interior of the vacuum pump via the cooling gas inlet, so that the vacuum pump and the components to be cooled, which delimit the hollow region, are locally cooled directly in the region of the heat generation. Because the hollow areas provided for cooling are separated from the pump chamber of the vacuum pump, impairment of the pumping action by the cooling gas is avoided, as is impairment of the cooling effect by the gas to be pumped, so that efficient cooling is ensured in efficient pumping operation.

The vacuum pump can be realized with very little effort, since only one additional inlet for the cooling gas and one hollow area or several hollow areas for the cooling gas are to be provided. As the cooling gas, e.g. the atmospheric air can be used, which is present at the cooling gas inlet, so that no special cooling gas must be provided.

Advantageous embodiments are described in the subclaims, the description and the figures.

According to an advantageous embodiment, at least one hollow region and in particular each hollow region is gas-conductively connected to the pump outlet. The cooling gas present at the cooling gas inlet can then be sucked into the cooling gas inlet by the suction of a backing pump connected to the pump outlet and sucked through the hollow region or the hollow regions.

A backing pump is particularly useful in vacuum pumps operating in the high purity vacuum environment, such as turbomolecular pumps The rule used anyway and can serve to suck the conveyed into a fore-vacuum or Vorvakuumraum the vacuum pump gas and thereby compressing from a prevailing in the Vorvakuumbereich prevacuum pressure to a higher pressure, in particular to atmospheric pressure. The fore-vacuum region preferably forms the downstream end of the pump chamber. The maximum backing pressure maintained by the backing pump may be adjusted to operate the vacuum pump upstream pump stages which compress against the backing pressure in the region of their optimum pumping performance and to achieve minimum ultimate pressures at the pump inlet.

In the presence of a gas-conducting connection between the one or more hollow areas and the pump outlet, the cooling gas can be sucked by the suction of the backing pump through the cooling gas inlet and conveyed through the hollow areas, so that a defined cooling gas flow and a forced cooling of the vacuum pump can be achieved without an additional Conveyor for the cooling gas is necessary. The hollow region or each hollow region can open into a region arranged upstream of the pump outlet, in particular a pre-vacuum region, of the pump chamber.

In view of the suction rates of available backing pumps, a good cooling effect is achieved in spite of the load of the backing pump with the cooling gas flow in addition to the pumping gas flow, without significantly affecting the backing pressure in the vacuum pump and thus the pumping power of the vacuum pump.

In principle, it is preferred that the cooling gas flow entering through the cooling gas inlet can be regulated, for example by adjustability of the Flow cross section of the cooling gas inlet. The desired flow cross-section can be determinable or adjustable, for example, via a capillary of the vacuum pump or the like. The cooling gas flow can then be adjusted in particular even in the case of a gas-conducting connection between the hollow regions and the pump outlet so that the cooling gas flow causes no disturbing impairment of the pumping action.

According to one embodiment, a cooling gas outlet is provided for the cooling gas, with which at least one hollow region and in particular each hollow region is gas-conductively connected. The gas cooling can then be realized substantially independently of the pumping process taking place in the pump chamber, and the hollow regions can be completely separated from the pump chamber within the vacuum pump. The cooling gas can be introduced into the vacuum pump via the cooling gas inlet, through which one or more hollow regions are conveyed and discharged from the vacuum pump at the cooling gas outlet.

A separate cooling gas outlet has the advantage that it is possible to choose between various provisions for conveying the cooling gas through the hollow region. For example, to generate the cooling gas flow, a compressor may be connected to the cooling gas inlet, which compresses the cooling gas, for example atmospheric air, and delivers it under pressure into the cooling gas inlet. On the other hand, the cooling gas outlet can also be connected to a backing pump, so that the delivery of the cooling gas is accomplished by the suction of the backing pump. For this purpose, a gas line can be connected to the cooling gas outlet, which opens into a backing tube connecting the pump outlet of the vacuum pump with the backing pump, so that at the inlet of the backing pump, the total gas flow of pumping gas flow and cooling gas flow is introduced. The gas line can The cooling gas outlet of the vacuum pump also connect directly to the backing pump and open, for example, directly into a pump chamber of the backing pump.

Preferably, at least one hollow region and in particular each hollow region is separated from the pump chamber in a substantially gas-tight manner. As a result, an increase in the existing in the pump chamber gas pressure due to the cooling gas flow and a concomitant deterioration of the pump power can be largely avoided. The refrigerant gas delivered to the pump may be e.g. be discharged through a Kühlgasauslass as described above. The gas-tight separation also includes an embodiment in which the hollow areas and the pump space are connected to one another outside the vacuum pump and thus only indirectly to one another by gas conduction, e.g. via a fore-vacuum hose of a backing pump which promotes the pumping gas and the cooling gas.

According to a further advantageous embodiment, at least one hollow region and in particular each hollow region downstream of all provided for pumping the gas present in the pump space provided pumping stages of the vacuum pump with the pump chamber or with the pump outlet gas-conducting. The at least one or each hollow region is preferably separated gas-tight from the regions of the pump chamber arranged upstream thereof, ie, the hollow region is connected to the pump chamber or the pump outlet in a gas-conducting manner exclusively downstream of all pump stages, for example in the region of a fore-vacuum region. As a result, an impairment of the pumping power by the cooling gas can be largely avoided, since the reaching into the downstream region of the pump chamber or in the pump outlet cooling gas, for example, directly from a connected to the pump outlet Pre-pump can be discharged without the prevacuum pressure increases significantly.

As pumping stages are e.g. one or more molecular and especially turbomolecular pumping stages provided. Alternatively or in addition to one or more turbomolecular pumping stages, one or more Holweck pumping stages, Siegbahn pumping stages, Gaede pumping stages or side channel pumping stages can be provided, in particular downstream of the one or more turbomolecular pumping stages.

According to one embodiment, at least one hollow region and in particular each hollow region is formed as a channel. Compared to an extended hollow region, this embodiment has the advantage that the cooling effect achieved can be locally targeted and precisely adjusted by a corresponding channel guide anywhere in the vacuum pump. At least one channel, and in particular each channel, may have an elongate shape over at least part of its length, and more particularly over at least approximately its entire length, and e.g. be formed substantially tubular or längsschlitz- or longitudinally gap-shaped.

In principle, a plurality of channels may be provided for the cooling gas, which may be connected to the cooling gas inlet or gas-conducting together. In this case, a plurality of channels may be gas-conductively connected in series or parallel to one another in the flow direction. An embodiment with several mutually branched channels is possible. In order to achieve a sufficient cooling effect throughout the pump, it is preferably provided that at least one channel or several channels taken together have a length which is at least half and preferably at least one-fold, two-fold or three-fold Flow diameter of a suction inlet flange forming the pump inlet corresponds to the vacuum pump.

Preferably, at least one channel and in particular each channel is substantially annular, in particular annular, or annular segment-shaped, in particular annular segment-shaped, around an axis of rotation of the vacuum pump. The vacuum pump may, in principle, be designed at least approximately rotationally symmetrically with respect to the axis of rotation, in order, for Rotate the rotating components of the pump stages. In this case, a sufficient and uniform cooling effect can be achieved by an annular channel in the entire vacuum pump. For this purpose, at least one channel or a plurality of channels together may cover at least 50%, preferably at least 75% and particularly preferably at least approximately the entire angular range defined relative to the axis of rotation of the vacuum pump.

The respective channel may have a radial distance from the axis of rotation over part of its length or at least approximately its entire length and may be e.g. be arranged in the distance range which extends from half to the entire outer diameter of the backing pump. The respective channel may for example have the shape of an annular gap, a ring slot, a ring tube or a segment of a corresponding ring shape.

In order to achieve sufficient cooling of the vacuum pump everywhere, at least two channels can be provided for the cooling gas, which in particular extend in different directions around the axis of rotation of the vacuum pump. The channels can be connected at one of their ends in each case directly to the gas inlet gas-conducting with the cooling gas inlet and / or connected to each other at the other end gas-conducting be or open into a common area of the vacuum pump. In principle, a plurality of channels spaced apart in the axial direction, ie in the direction of rotation axes, may also be provided.

In principle, at least apart from possible branches to further channels or to further hollow areas and at least over part of its length and in particular over at least approximately its entire length, a channel may have a closed cross-section perpendicular to its longitudinal extent.

According to one embodiment, at least one channel and in particular each channel forms at least over a part of its length and in particular over at least approximately its entire length a flow cross-sectional area for the cooling gas which is at most as large as the flow cross-sectional area of the pump outlet and in particular smaller than the flow cross-sectional area of the pump outlet , The fore-vacuum pressure is then increased by the cooling possibly at most slightly and also is achieved anywhere in the vacuum pump to the respective requirements sufficient cooling.

Preferably, at least one hollow region and in particular each hollow region at least partially has a closed cross-section, which in particular is completely bounded by at least one static component of the vacuum pump. As a result, an effective sealing of the hollow region from the pump chamber and an efficient cooling of the static pump components and thus of the vacuum pump as a whole can be achieved. The hollow region or the hollow regions may be formed as a channel which, as described above, at least apart from possible branches to other channels or to other hollow regions and at least over a part of its Length and in particular over at least approximately its entire length may have a closed cross-section.

In an embodiment that is particularly simple to implement, the closed cross-section of one or each hollow region, in particular channel, is completely delimited by at least two static components of the vacuum pump, at least in a section of the hollow region or at least in a longitudinal section of the channel. The hollow region or channel is thus surrounded by at least two components, which partially limit the cross section of the hollow region in each case. The hollow region may be formed, at least partially, by a groove-shaped recess or recess of a component which is covered by the other component for forming the hollow region. The hollow region or channel can also be formed by a gap or slot, in particular annular gap or annular slot, between the components. In order to seal the hollow region, the two components can abut each other directly on the edge of the hollow region in a gas-tight manner and / or in each case against a common sealing element.

A structurally particularly advantageous embodiment is that in a lower part of the vacuum pump, which is at least partially disposed in a lower region of the pump and forms, for example, a part of a housing of the vacuum pump or an enclosure for a rotary bearing and / or a drive of the pump, a groove is formed whose groove walls partially define the hollow region. Another, preferably flat-shaped component can close the groove opening and thereby complete the transformation of the hollow region such that the hollow region has a closed cross-section. The groove can thereby jump in the axial direction in the lower part. The flat-shaped component may, for example, in an existing axially-receding and in particular be defined through opening of the lower part through which the groove is accessible and in the example, a rotary bearing and / or a drive of the pump can be used. The groove preferably has a substantially annular or annular segment-shaped course and the further component can accordingly be formed by a ring-shaped or annular-segment-shaped and preferably flat-shaped ring or partial ring.

In principle, the closed cross-section may also be completely delimited by at least one section of the hollow region or longitudinal section of the channel and, in particular, everywhere completely by exactly one static component of the vacuum pump. The hollow region or channel can be formed by a continuous recess in the solid material of the respective component.

Preferably, at least one hollow region and in particular each hollow region is at least partially disposed in a region of the vacuum pump, which is spaced in the rotational axis direction from the pumping stages of the vacuum pump and which is also referred to as the lower region. In the lower region can be arranged, for example, a rotary bearing for a rotor shaft and / or a drive of the vacuum pump. A hollow region or each hollow region can be arranged, for example, in a lower part or at least partially bounded by it. A hollow region can also be delimited at least partially by a baffle plate or a flat-shaped component of the vacuum pump which is arranged in particular in the lower region. In order to ensure a good heat transfer, the conversion of one or each hollow region may be at least partially and in particular completely formed by a heat-conducting and in particular metallic material.

As the cooling gas can be used in the simplest case, the atmospheric air, which is present at the cooling gas inlet, preferably at atmospheric pressure and / or room temperature. In either case, a cooling gas is introduced into the cooling gas inlet, which is cooler than the desired maximum temperature of the pump. Upstream of the cooling gas inlet, the cooling gas may be passed through an air cooling system disposed outside the vacuum pump or on the outside of the vacuum pump or through flow channels disposed outside the vacuum pump.

Under an inlet and an outlet of the vacuum pump, in the present description, one is always more accessible from outside the vacuum pump and the outside of the vacuum pump is gas-conducting with the interior of the vacuum pump, which e.g. is limited by a housing of the vacuum pump to understand connecting inlet or outlet. The cooling gas inlet accordingly connects the exterior of the vacuum pump with the interior of the vacuum pump in which the hollow area or the hollow areas are arranged. An inlet or outlet may include a flange surrounding a respective inlet or outlet port, but may also be formed by a simple inlet or outlet port.

In principle, the vacuum pump can comprise a plurality of hollow areas. When reference is made to a "hollow region" or "channel" or "hollow regions" or "channels" in the present description, the respective description is always equally applicable to at least one hollow region or channel, which may also be the only one Hollow region or channel is to refer to several hollow areas or channels and in particular to all hollow areas or channels. The vacuum pump may also have a plurality of cooling gas inlets, each gas-conducting connected to at least one hollow portion.

Another object of the invention is a vacuum arrangement with a vacuum pump according to the present invention, wherein at the cooling gas inlet of the vacuum pump, a cooling gas for cooling the vacuum pump is provided and at the pump inlet of the vacuum pump is connected to a separate pump from the cooling gas inlet with a gas to be pumped. While the recipient preferably forms a closed, substantially gas-tight volume connected to the pump inlet, the cooling gas provided at the cooling gas inlet may be, for example, atmospheric air, in which case the cooling gas inlet may simply be exposed to the normal atmosphere. At the pump outlet, a backing pump can be connected, which removes the gas pumped by the vacuum pump and optionally additionally the cooling gas. The embodiments described above with respect to the vacuum pump and their use in a vacuum arrangement, in particular with a roughing pump, represent correspondingly advantageous embodiments of the vacuum arrangement according to the invention.

The invention further relates to a method for operating a vacuum pump according to the present invention or a vacuum arrangement according to the invention with a vacuum pump according to the present description, wherein at the cooling gas inlet of the vacuum pump, a cooling gas for cooling the vacuum pump, in particular atmospheric air, is provided and wherein at the pump inlet the vacuum pump is provided a gas to be pumped separated from the cooling gas. The gas to be pumped can be provided in a closed recipient, while as the cooling gas In particular, the normal atmospheric air can be used, wherein the cooling gas inlet of this atmospheric air can be exposed. The advantageous embodiments described above with respect to the vacuum pump and the vacuum arrangement and their use represent correspondingly advantageous embodiments of the method according to the invention. Preferably, the suction of a backing pump is used to convey both the cooling gas and the pumping gas.

Fig. 1

eine Vakuumpumpe gemäß einer Ausführungsform der Erfindung im Axialschnitt,

Fig. 2

einen unteren Bereich einer Vakuumpumpe gemäß einer weiteren Ausführungsform der Erfindung in schematischer Darstellung im Querschnitt,

Fig. 3

einen unteren Bereich einer Vakuumpumpe gemäß einer weiteren Ausführungsform der Erfindung in schematischer Darstellung im Axialschnitt,

Fig. 4

ein Unterteil einer Vakuumpumpe gemäß einer weiteren Ausführungsform der Erfindung in Seitenansicht,

Fig. 5

das in Fig. 4 gezeigte Unterteil in einer entlang der Linie A-A von Fig.4 geschnittenen Darstellung,

Fig. 6

das in Fig. 4 und 5 gezeigte Unterteil in einer entlang der Linie B-B von Fig. 4 geschnittenen Darstellung,

Fig. 7

einen in das in Fig. 4 bis 6 gezeigte Unterteil zur Bildung eines Kühlgaskanals einsetzbaren Ring, und

Fig. 8

den in Fig. 7 gezeigten Ring in einer entlang der Linie A-A von Fig. 7 geschnittenen Darstellung.

Hereinafter, the present invention will be described by way of example with reference to advantageous embodiments with reference to the accompanying drawings. Show it:

Fig. 1

a vacuum pump according to an embodiment of the invention in axial section,

Fig. 2

a lower portion of a vacuum pump according to another embodiment of the invention in a schematic representation in cross section,

Fig. 3

a lower portion of a vacuum pump according to another embodiment of the invention in a schematic representation in axial section,

Fig. 4

a lower part of a vacuum pump according to another embodiment of the invention in side view,

Fig. 5

this in Fig. 4 shown lower part in one along the line AA of Figure 4 cut representation,

Fig. 6

this in Fig. 4 and 5 shown lower part in one along the line BB of Fig. 4 cut representation,

Fig. 7

one in the in 4 to 6 shown lower part for forming a cooling gas duct usable ring, and

Fig. 8

the in Fig. 7 shown ring in one along the line AA of Fig. 7 cut illustration.

In the Fig. 1 The vacuum pump shown includes a pump inlet 10 surrounded by an inlet flange 12, a pump outlet 14 surrounded by an outlet flange 16, and a pumping space 18 therebetween through which the gas to be pumped is conveyed during operation of the pump is called the scooping room. An upper housing part 20 and a lower part 22 form a housing of the vacuum pump.

The vacuum pump comprises a rotor shaft 26, which is rotatably mounted in the vacuum pump about a rotation axis 28 by a magnetic bearing 30 and a ball bearing 32, which is supplied with lubricant by a lubricating device 34. An electric drive 36 serves to rotate the rotor shaft 26.

The magnetic bearing 30 and the pumping stages described below are received in the housing top 20. The lower part 22 forms an enclosure for the ball bearing 32 and for the lubricating device 34, which are located in the lower portion 24 of the vacuum pump, and for the drive 36. The lower part 22 is formed by a base portion 60 and a functional portion 62 and includes a continuous

Opening 72 and a groove 76, these components with respect to 4 to 6 are explained in more detail.

The vacuum pump comprises a plurality of rotor disks 38 arranged on the rotor shaft 26 and extending in the radial direction and provided with radial blades. Stator disks 40 are also provided, which likewise extend in the radial direction, are provided with radial blades and which are arranged and in the housing the vacuum pump are set to face the rotor disks 38 at a small axial distance. A rotor disk 38 in each case forms a turbomolecular pumping stage of the vacuum pump with an opposing stator disk 40.

Downstream of the turbomolecular pumping stages follow three nested Holweck pump stages of the vacuum pump, which are formed by a plurality of cylinder jacket-shaped concentric to the rotation axis 28 arranged Holweckstatoren 42 and also cylinder jacket-shaped and concentric with the axis of rotation 28, connected to the rotor shaft 26 Holweckrotorhülsen 44. A pump-shaped radial surface of a Holweck stator 42 forming several helical grooves is in each case opposite a smooth radial surface of a Holweck rotor sleeve 44 at a small radial distance, so that a thin gap is formed between the surfaces. The opposing surfaces together form each a Holweck pumping stage, wherein in the operation of the vacuum pump, the gas molecules are driven in the helical grooves and thus conveyed in the axial direction.

Downstream of the three series-connected Holweck pump stages, a fore-vacuum region 46 of the vacuum pump is formed, in which the gas delivered by the pumping stages is collected, which is subsequently discharged via the pump outlet 14 which is connected to the fore-vacuum region 46 in a gas-conducting manner.

The vacuum pump further comprises a cooling gas inlet 48, which is formed in the lower part 22 and connects a channel 50 formed in the interior of the lower part 22 for the cooling gas gas-conducting with the pump exterior and the atmospheric air present there.

The cooling gas inlet 48 extends in the radial direction into the vacuum pump and opens into the cooling gas channel 50, which has a substantially circular cross-section, extends substantially semicircular around the rotation axis 28 and opens into the pump outlet 14.

When a backing pump is connected to the pump outlet 14, atmospheric air can be conveyed through the cooling gas inlet 48 into the vacuum pump and through the channel 50 to the pump outlet 14 by the suction of the backing pump 48 and exhausted there by the roughing pump. In this case, the atmospheric air cools the regions of the lower part 22 delimiting the channel 50, which prevents excessive heating in the operation of the vacuum pump.

In principle, more cooling gas channels 50 and / or a plurality of cooling gas inlets 48 may be provided, which may each be gas-conductively connected to the pump outlet 14.

Fig. 2 shows a lower portion 24 of a vacuum pump according to another embodiment in cross section, which substantially the in Fig. 1 corresponds shown vacuum pump. The pump components, the may be included in the lower part 22 such as a as in Fig. 1 shown pivot bearing or a lubricating device are in Fig. 2 not shown and the lower part 22 is instead shown continuously.

In the Fig. 2 The pump shown has two cooling gas passages 50, 52 respectively connected in a gas-conducting manner to the cooling gas inlet 48, which extend from the cooling gas inlet 48 in opposite directions substantially in a semicircular shape around the axis of rotation 28 and open into the pump outlet 14. As a result, an effective cooling is achieved over the entire angular range around the rotation axis 28. The gas-conducting connection between the fore-vacuum region of the vacuum pump and the pump outlet 14 is in Fig. 2 represented by the dashed circle 56.

Fig. 3 shows the lower portion 24 of a vacuum pump according to another embodiment of the invention in axial section with a lower part 22, as shown in Fig. 2 is shown throughout. The vacuum pump has a plurality of cooling gas channels 50, 54, each gas-conducting with a in Fig. 3 Not shown cooling gas inlet are connected.

The vacuum pump comprises on the one hand channels 50, which are completely bounded by the solid material of the lower part 22. On the other hand, the vacuum pump comprises channels 54, which are surrounded on the one hand by the groove walls of grooves which are provided on the radial outer sides of the lower part 22, and on the other by outer plates 58 which are gas-tightly connected to the lower part 22 and the channels 54 in Limit the radial direction to the outside. The outer plates 58 define, together with the lower part 22, an approximately triangular cross-section of the individual channels 54.

Fig. 4 shows a lower part 22 of a vacuum pump according to another embodiment of the invention in side view. The lower part 22 comprises an approximately cylindrical about the axis 28 extending around base portion 60 which forms the lower portion 24 of the vacuum pump in the use of the lower part 22 in a vacuum pump. The lower part 24 also comprises a relative to the base portion 60 in the axial direction nozzle-like projecting and to the axis 28 substantially rotationally symmetrical functional portion 62, which cooperates in the manner described below with the components directly involved in the pumping function of the vacuum pump.

The functional portion 62 includes a radially protruding collar portion 64 having a plurality of helical grooves 66 extending around the axis 28. When used in the vacuum pump, the portion 64 forms with the inner surface of a hollow rotor sleeve 44 rotating about the axis 28 (see FIG Fig. 1 ) a gap with a small radial gap width. The section 64 and the Holweckrotorhülse 44 work together in the manner of Holweckpumpstufe together and form a dynamic seal, which seals the pump chamber with respect to the adjacent cavities of the pump.

The base portion 60 includes a pump outlet 14 and a gas outlet gas-tightly separated from the pump outlet 14 68.

FIGS. 5 and 6 show that in Fig. 4 shown lower part 22 in a along the line AA or BB of Fig. 4 cut illustration. The lower part 22 comprises a cooling gas inlet 48 and a groove 70 designed to delimit a cooling gas channel 50, which projects in the axial direction and runs in a circle about the axis 28 to the cooling gas outlet 68, the groove 70 having an angular range of approximately 220 ° covers. As in Fig. 6 shown, the groove 70 is accessible via an opening 72 of the lower part 22 from the outside.

FIGS. 7 and 8 show a circular ring 74 with a flat cross-section, which can be fixed in the opening 72, that the ring 74, the groove 70 closes and forms a closed cross section for the cooling gas channel 50 with the groove walls.

The lower part 22 also includes a groove 76 (FIG. Fig. 5 ) to limit the Vorvakuumbereichs 46 and a gas-conducting connected pump outlet 14. As with reference to FIGS. 5 and 6 As can be seen, the cooling gas channel 50 extends in this embodiment in the axial direction below the pump outlet 14 and is completely gas-tightly separated from the fore-vacuum region 48 and the pump chamber 18. To generate a flow of cooling gas in the cooling gas channel 50, for example, compressed air can be provided at the cooling gas inlet 48. Alternatively, the cooling gas outlet 68 may be connected outside the vacuum pump and thus downstream of the pump outlet 14 to a backing pump, which may also be connected to the pump outlet 14.

The opening 72 extends in the axial direction through the base portion 60 and the functional portion 62 of the lower part 22, wherein in the region of the functional portion 62, a drive 36 (see Fig. 1 ) and in the region of the base portion 60, a pivot bearing 32 of the pump in the opening 72 can be fixed, so that the lower part 22 forms an enclosure for these components. The lower end of the opening 72 is closable with a lid, not shown.

LIST OF REFERENCE NUMBERS

10

pump inlet

12

inlet flange

14

pump outlet

16

outlet flange

18

pump room

20

Housing top

22

lower part

24

lower area

26

rotor shaft

28

axis of rotation

30

magnetic bearings

32

ball-bearing

34

lubricator

36

drive

38

rotor disc

40

stator

42

Holweckstator

44

Holweckrotorhülse

46

pre-vacuum

48

Cooling gas inlet

50, 52, 54

Hollow area, channel

56

circle

58

outer panel

60

base section

62

function section

64

collar section

66

groove

68

cooling gas outlet

70

groove

72

opening

74

ring

76

groove

Claims (10)

1. A vacuum pump, in particular a turbomolecular pump, having a pump inlet (10), a pump outlet (14) and a pump space (18) for a gas to be pumped arranged between the pump inlet (10) and the pump outlet (14),
   as well as having at least one cooling gas inlet (48) for a cooling gas for cooling the vacuum pump and having at least two hollow regions (50, 52, 54) for the cooling gas connected in a gas conducting manner to the cooling gas inlet (48) and arranged outside the pump space (18),
   characterized in that
   the hollow regions (50, 52, 54) are arranged in a heat conducting lower part (22) of the vacuum pump,
   wherein the hollow regions (50, 52, 54) are each formed as a passage; and
   wherein at least two passages (50, 52, 54) are provided which extend in different directions about an axis of rotation (28) of the vacuum pump.
2. A vacuum pump in accordance with claim 1,
   characterized in that
   the hollow regions (50, 52, 54) are connected in a gas conducting manner to the pump outlet (14) and in particular open into the pump outlet (14) or into a region arranged upstream of the pump outlet (14), in particular into a backing region (46), of the pump space (18).
3. A vacuum pump in accordance with claim 1 or claim 2, characterized in that
   a cooling gas outlet (68) for the cooling gas is provided to which the hollow regions (50, 52, 54) are connected in a gas conducting manner.
4. A vacuum pump in accordance with any one of the preceding claims,
   characterized in that
   the hollow regions (50, 52, 54) are separated in a substantially gas tight manner from the pump space (18) or are connected to the pump space (18) or to the pump outlet (14) in a gas conducting manner downstream of all the pump stages (38, 40, 42, 44) of the vacuum pump provided for pumping the gas present in the pump space (18).
5. A vacuum pump in accordance with any one of the preceding claims,
   characterized in that
   the passages (50, 52, 54) extend substantially in ring shape or in ring segment shape about an axis of rotation (28) of the vacuum pump.
6. A vacuum pump in accordance with claim 5,
   characterized in that
   the passages (50, 52, 54) form a flow cross-sectional surface for the cooling gas over at least a part of their length and in particular over at least approximately their total length, said flow cross-sectional surface being so large at a maximum as the flow cross-sectional surface of the pump outlet (14) and in particular being smaller than the flow cross-sectional surface of the pump outlet (14).
7. A vacuum pump in accordance with any one of the preceding claims,
   characterized in that
   the hollow regions (50, 52, 54) each have at least regionally and in particular everywhere a closed cross-section which is completely bounded by at least one static component (22, 58, 74) of the vacuum pump.
8. A vacuum pump in accordance with claim 7,
   characterized in that
   the closed cross-section is bounded at least in one section of the hollow regions (50, 52, 54) and in particular everywhere completely by at least two static components (22, 58, 74) of the vacuum pump.
9. A vacuum arrangement having a vacuum pump in accordance with any one of the preceding claims, wherein a cooling gas for cooling the vacuum pump is provided at the cooling gas inlet (48) of the vacuum pump and a recipient having a gas to be pumped and separate from the cooling gas inlet (48) is connected to the pump inlet (10) of the vacuum pump.
10. A method of operating a vacuum pump in accordance with any one of the claims 1 to 8 or of operating a vacuum arrangement having a vacuum pump in accordance with claim 9, wherein a cooling gas for cooling the vacuum pump, in particular atmospheric air, is provided at the cooling gas inlet (48) of the vacuum pump; and wherein a gas to be pumped which is separate from the cooling gas is provided at the pump inlet (10) of the vacuum pump.

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