EP4296520A1 - Pumping unit - Google Patents

Abstract

The invention relates to a pump unit for a vacuum pump, in particular a turbomolecular vacuum pump, or for a vacuum system, with at least one Holweck pump stage, which comprises one or more Holweck sleeves rotating about an axis of rotation during pumping operation and one or more Holweck stators, each of which is at least on a side facing a Holweck sleeve has a Holweck web, wherein the Holweck stator or - in the case of several Holweck stators - the outer, most radially outer Holweck stator in an inflow area comprises several, in particular two, three or four, radial inflow openings, which are distributed in the circumferential direction and have support sections running in the axial direction are separated from each other.

Description

The invention relates to a pump unit for a vacuum pump, in particular a turbomolecular vacuum pump, or for a vacuum system, with at least one Holweck pump stage, which comprises one or more Holweck sleeves rotating about an axis of rotation during pumping operation and one or more Holweck stators, each of which is at least on a side facing a Holweck sleeve has a Holweck bridge.

The invention further relates to a vacuum pump, in particular a turbomolecular vacuum pump, with at least one pump unit as disclosed herein. The invention also relates to a vacuum system with at least one vacuum chamber, at least one pump unit as disclosed herein, and at least one recipient to be evacuated.

Pump units of the type mentioned at the beginning are basically known and in practice usually have, in addition to the at least one Holweck pump stage, one or more turbomolecular pump stages, the rotating components of which - namely the rotor blades - rotate during operation together with the Holweck sleeve or sleeves around the common axis of rotation.

Such a pump unit can be part of an independent vacuum pump, which is fluidly connected to a respective recipient for a respective pump application in order to evacuate it. The pump unit is then located in its own pump housing, which forms the outer housing of the vacuum pump.

Such vacuum pumps are also known in the form of so-called split-flow pumps, in which the suction does not take place or not only via an axial suction opening and thus parallel to the axis of rotation, but rather their pump housing, for example a so-called box-type housing, one or more, along the Axis of rotation has radial suction openings arranged at a distance from one another. These radial suction openings of a split flow pump are also referred to as radial taps, intermediate taps, ports or suction ports. During operation, each radial suction opening of the split flow pump is connected to a corresponding opening of the recipient to be evacuated.

In addition, pump units of the type mentioned above are known, which also have a housing and are in principle independent vacuum pumps, but in practice are inserted into another housing for pumping operation. Such pump units are also referred to as cartridge pumps and their housings are also referred to as cartridge sleeves or simply as pump housings. The further housing can be a separate housing which, together with the pump unit accommodated therein, forms an independent vacuum pump. The further housing can be, for example, a box-type housing, i.e. an independent split-flow pump can have in its box-type housing - i.e. the outer housing, also simply referred to as a pump housing - either a pump unit without its own housing or a pump unit with its own housing, in particular a cartridge pump.

Alternatively, the further housing can be an integral part of a vacuum system which, in addition to a vacuum chamber which serves to accommodate the pump unit, includes a recipient which is in fixed flow connection to this vacuum pump and which can be evacuated with the pump unit accommodated in the vacuum chamber.

A pump unit with a housing - hereinafter also referred to as a base housing -, in particular a cartridge vacuum pump, can consequently be accommodated, in particular inserted, into various other housings, which will be referred to below under the common term "outer housing". The outer housing can either be an independent housing - as with a pump unit without a base housing - or the outer housing can form an integral part of a vacuum system as a chamber housing.

In the present disclosure, the or each opening of a respective outer housing that is in fluid communication with a respective pump unit accommodated therein is uniformly referred to as a radial tap. If the pump unit has its own base housing, i.e. it is in particular a cartridge pump, then a respective opening of this base housing, which is fluidly connected to a radial tap of the outer housing, is referred to in the present disclosure as a radial suction opening to avoid confusion to avoid.

Holweck pump stages have one or more Holweck stators. Radially inside the Holweck stator or - in the case of several Holweck stators - the outer, most radially outer Holweck stator is the Holweck sleeve, which rotates around the axis of rotation during operation. If we talk about “the Holweck stator” below, then in the event that the Holweck pump stage includes several Holweck stators, what is meant is the outer, most radially outer Holweck stator.

On its side facing the Holweck sleeve, the Holweck stator is provided with one or more Holweck webs, each of which runs around the axis of rotation along a curve with a slope different from zero. As a result, the Holweck stator is on its side facing the respective Holweck sleeve the Holweck webs are provided with Holweck channels which, together with the facing side of the Holweck sleeve, form a pump-active area of the Holweck pump stage.

So that in a split-flow pump the gas to be pumped can reach this pump-active area of the Holweck pump stage from the radial tap of the outer housing, an opening aligned with the radial tap is formed in the Holweck stator, which is referred to as a radial inflow opening in the present disclosure. This inflow opening forms an inflow area of the Holweck pump stage, whose axial position - relative to the axis of rotation - is thus coordinated with the corresponding position of the radial tap.

The object of the invention is to increase the suction speed in the inflow area of the Holweck pump stage in a pump unit of the type mentioned at the outset and thus in particular to improve the vacuum performance of split-flow vacuum pumps that have one or more Holweck pump stages.

This problem is solved by the features of the independent claims.

In the pump unit, it is provided according to the invention that the Holweck stator or - in the case of several Holweck stators - the outer, most radially outer Holweck stator in an inflow area comprises several, in particular two, three or four, radial inflow openings, which are distributed in the circumferential direction and through in the axial Directional support sections are separated from each other.

The multiple radial inflow openings increase the inflow area in the circumferential direction. Instead of a single radial inflow opening, there are several inflow openings distributed in the circumferential direction available. The support sections ensure the required mechanical stability of the Holweck stator.

The axial support sections can each run exactly axially, i.e. parallel to the axis of rotation, or also obliquely. In any case, the axial support sections connect the two stator sections axially adjacent to the inflow area.

As far as the dimensions in the circumferential direction are concerned, it is possible, but not necessary, for all inflow openings to have the same circumferential length. This applies accordingly to the support sections.

According to some embodiments, the radial inflow openings each have an elongated shape. The circumferential length of the inflow openings is therefore greater than their axial height.

According to some developments, it can be provided that the radial inflow openings lie on a circle around the axis of rotation, with the radius of the circle being perpendicular to the axis of rotation. However, this is not mandatory. Alternatively, it can be provided that the radial inflow openings lie in a plane inclined relative to the axis of rotation or on a curve running around the axis of rotation with a gradient different from zero. In particular, the radial inflow openings can lie on a helix. As a result, the course of the inflow openings around the axis of rotation therefore contains an axial component. With regard to a pressure distribution within the Holweck pump stage or the pump-active region of the Holweck pump stage formed by the Holweck stator together with the respective Holweck sleeve, such a course of the radial inflow openings of the Holweck stator can be advantageous.

In the context of the present disclosure, a plane inclined relative to the axis of rotation is understood to mean a plane that is not perpendicular to the axis of rotation runs, but runs obliquely to the axis of rotation, so that a normal on the plane with the axis of rotation encloses an angle other than zero that is less than 90 °.

According to some embodiments, it can be provided that the support sections are each designed as a web or strut. In particular, the support sections can each extend in the circumferential direction over an angle in the range of 3° to 30°, in particular from 5° to 20°, in particular over an angle of 10°. The narrower the support sections, the greater the openness of the Holweck stator in the inflow area provided by all inflow openings. The strength of the support sections can be minimized in such a way that sufficient mechanical stability of the Holweck stator is guaranteed and the openness of the inflow area is maximized.

According to some developments, the radial inflow openings and/or the support sections can be at least partially free of Holweck webs. At least some of the Holweck bridges can therefore be interrupted in the inflow area. As a result, the openness of the Holweck stator in the inflow area can be further increased and the suction speed can thus be further improved.

In some embodiments, the Holweck pump stage can be surrounded by a base housing which has at least one radial suction opening axially at the level of the inflow area of the Holweck stator.

As mentioned at the beginning, a pump unit with a base housing can in particular be designed in such a way that it can be accommodated, in particular inserted, into another housing. Such pump units are also referred to as cartridge pumps. The base housing is also known as the pump housing or cartridge sleeve. As also already mentioned, the further housing is referred to as an outer housing in the present disclosure. The The outer housing can be the pump housing of an independent vacuum pump, for example a so-called box-type housing, or the outer housing can delimit a vacuum chamber used to accommodate the pump unit, which is part of a vacuum system also comprising a recipient.

According to some exemplary embodiments, it can be provided that a radial gap running around the axis of rotation is formed axially at the level of the inflow area of the Holweck stator between the Holweck stator and the base housing. A flow entering the Holweck pump stage via the base housing can be distributed through this radial gap in the circumferential direction and thus reach the pump-active area between the Holweck stator and the Holweck sleeve via all radial inflow openings of the Holweck stator and consequently practically over the entire circumference.

The radial gap can lie on a circle around the axis of rotation or in a plane inclined relative to the axis of rotation or on a curve running around the axis of rotation with a slope other than zero, in particular on a helix. In particular, the course of the radial gap can correspond to the course of the inflow openings of the Holweck stator.

According to some embodiments, the base housing comprises several, in particular two, three or four, radial suction openings arranged axially at the level of the inflow area of the Holweck stator and distributed in the circumferential direction and separated from one another by holding sections running in the axial direction. As a result, the base housing has a structure axially at the level of the inflow area of the Holweck stator like the Holweck stator itself and is therefore also provided with an increased openness due to the several radial suction openings.

In particular, it can be provided that the number of radial inflow openings of the Holweck stator is equal to the number of radial suction openings of the base housing.

Furthermore, it can be provided that the circumferential lengths of the radial inflow openings of the Holweck stator are each at least substantially equal to the circumferential length of each of the radial suction openings of the base housing.

According to some exemplary embodiments, it can be provided that the support sections of the Holweck stator and the holding sections of the base housing are offset from one another in the circumferential direction. Such an arrangement can promote flow guidance, which leads to a further increase in the suction speed.

Possible developments of the base housing with regard to the radial suction openings and the holding sections that separate them from one another can correspond to the developments of the Holweck stator already mentioned above with regard to the radial inflow openings and the support sections that separate them from one another.

It can thus be provided that the radial suction openings of the base housing each have an elongated shape.

Furthermore, it can be provided that the radial suction openings of the base housing lie on a circle around the axis of rotation or in a plane inclined with respect to the axis of rotation or on a curve running around the axis of rotation with a slope different from zero, in particular on a helix. In particular, the course of the radial suction openings can correspond to the course of the radial inflow openings.

Furthermore, it can be provided that the holding sections of the base housing are each designed as a web or strut, in particular with the holding sections each extending in the circumferential direction over an angle in the range of 3° to 30°, in particular from 5° to 20°, in particular over one Angle of 10°.

The cross sections of the supporting sections of the Holweck stator and the cross sections of the holding sections of the base housing can be rectangular. However, this is not mandatory. In principle, other cross-sectional shapes are also possible, which are designed in particular with a view to optimizing flow and, for example, include a curved curve without corners. The cross section can be, for example, circular or elliptical or a rectangle or square with rounded corner areas.

A vacuum pump according to the invention, which is designed in particular as a turbomolecular vacuum pump, comprises at least one pump unit as disclosed herein and an outer housing in which the pump unit is accommodated, the outer housing having a radial tap axially at the level of the inflow area of the Holweck stator of the pump unit.

For example, the vacuum pump can be a split-flow vacuum pump with an outer housing, which is, for example, a so-called box-type housing. Such a vacuum pump can be used as an independent pump and fluidly connected to a respective recipient to be evacuated.

A vacuum system according to the invention comprises at least one vacuum chamber, at least one pump unit as disclosed herein and at least one recipient to be evacuated. The vacuum chamber comprises, as an outer housing, a chamber housing in which the pump unit is accommodated and which has a radial tap axially at the level of the inflow area of the Holweck stator of the pump unit, which is in flow connection with the recipient.

The pump unit of the vacuum pump can have its own base housing, so it can in particular be a cartridge vacuum pump. This also applies to the pump unit of the vacuum system.

In both cases, i.e. both in the case of a vacuum pump and in the case of a vacuum system, the outer housing can have several radial taps. It can be provided that a radial tap is assigned to one or more turbomolecular pump stages, or that several radial taps are assigned to several turbomolecular pump stages arranged one behind the other along the axis of rotation. Regardless of whether the outer housing has one or more radial taps, the outer housing can additionally have an axial suction opening. In the case of a pump unit with its own base housing, in particular a cartridge vacuum pump, the base housing can accordingly have an axial suction opening in addition to one or more radial suction openings. As already mentioned in the introduction, a flow entering through an axial suction opening runs at least essentially parallel to the axis of rotation of the pump unit.

According to some exemplary embodiments, a radial gap running around the axis of rotation can be present between the outer housing on the one hand and the Holweck stator or the base housing on the other hand, axially at the level of the radial tap of the outer housing. Such a radial gap creates a flow path that leads radially around the outside of the pump unit, which promotes the distribution of an incoming flow over the entire circumference and thus the use of all inflow openings of the Holweck stator and consequently leads to a further increase in the pumping speed.

The axial height of the radial gap can be chosen differently. The axial height can be the axial height of the inflow area of the Holweck stator are equivalent to. Alternatively, the radial gap can also have a smaller or larger axial height.

Furthermore - as with an optionally provided, above-mentioned radial gap between Holweck stator and base housing - it can be provided that the radial gap provided between the outer housing and Holweck stator or base housing is either on a circle around the axis of rotation or in a plane inclined with respect to the axis of rotation or on a The curve running along the axis of rotation has a gradient other than zero, in particular on a helix. In particular, the course of this radial gap can correspond to the course of the inflow openings of the Holweck stator and/or the course of the radial suction openings of an optionally present base housing.

In the case of a pump unit without its own housing, in particular if it is not a cartridge pump, but rather the at least one Holweck pump stage and possibly further pump stages, for example one or more turbomolecular pump stages, are accommodated in an outer housing forming the pump housing, such as in a split-flow pump with a box-type housing forming the outer housing, the annular gap is therefore provided between the inside of this outer housing and the outside of the Holweck stator.

In the case of a pump unit with its own base housing, for example a cartridge pump, the radial gap is then provided between the inside of the outer housing and the outside of the base housing.

The radial gap is limited axially in both directions, in particular on the axial area of the inflow area of the Holweck stator, ie the radial gap is located axially at the level of the inflow openings of the Holweck stator and - if optionally a base housing is provided - axially at the level of the radial suction opening or suction openings of the base housing.

Such an axial limitation of the radial gap arises to a certain extent automatically if, according to some embodiments of the invention, the radial gap is formed by a channel formed on the inside of the outer housing. Such a channel represents a recess running in the circumferential direction on the inside of the outer housing. The Holweck stator can rest with its outside on the areas of the inside of the outer housing that axially adjoin the circumferential channel. In addition, seals can be provided which ensure that the overall axial region of the arrangement comprising the pump unit and outer housing, which encompasses the inflow region of the Holweck stator, is sealed in order to avoid impairment of the suction speed in this inflow region.

Correspondingly, in the case of a pump unit with a base housing, it is the outside of the pump unit that lies against those areas of the inside of the outer housing that axially delimit the circumferential channel formed on this inside.

The radial gap can alternatively be formed by a channel which is formed on the outside of the Holweck stator or the base housing. The outside of the Holweck stator is formed by its support sections lying between the radial inflow openings. The channel on the outside of the Holweck stator and thus the radial gap can thus be formed in that the support sections are provided with a smaller radial thickness and spring back radially inwards relative to axially adjacent areas of the outside of the Holweck stator.

Correspondingly, in a pump unit with a base housing, the holding sections separating the radial suction openings are used to form a circumferential Channel and thus the radial gap spring back radially inwards compared to axially adjacent areas of the outside of the base housing.

A combination of both measures is also possible, i.e. the radial gap can be formed both by a channel formed on the inside of the outer housing and by a channel formed on the outside of the Holweck stator or the base housing.

In general, it can be provided that a channel formed on the inside of the outer housing, i.e. its channel base, can lie on a circle, although this is not mandatory. Depending on the respective situation, e.g. the space available in a customer chamber, the radial depth of the channel can vary in the circumferential direction.

In principle, it is also possible to provide an annular gap without a channel being formed on the inside of the outer housing or on the outside of the Holweck stator or the base housing, namely by arranging the Holweck stator or the base housing at a radial distance from the inside of the outer housing and axial sealing of this gap is ensured in such a way that an axially sealed radial gap is present axially at the level of the inflow area of the Holweck stator.

Alternatively or in addition to a radial gap, however formed, it can be provided according to some exemplary embodiments that the outer housing has a recess on its inside at least in the area of one of the support sections of the Holweck stator or a holding section of the base housing, preferably in the area of each support section or holding section . Such a recess exposes the respective support section or holding section radially on the outside, so that flow can flow around the support section or holding section radially on the outside. Such depressions can also be used for distribution an incoming flow over the entire circumference and thus enable full use of the inflow area of the Holweck stator, whereby the pumping speed of the pump unit can be further improved.

A turbomolecular pump stage, like the Holweck pump stage disclosed herein, can also have a radial inflow area. The embodiments of the radially outer Holweck stator disclosed herein with regard to its radial inflow area can therefore also be provided in a turbomolecular pump stage, namely in a stator spacer sleeve, which is hereby expressly disclosed. The stator spacer sleeve is arranged between two stator blades or adjacent to a stator blade of the turbomolecular pump stage. Analogous to the radially outer Holweck stator, the stator spacer sleeve can therefore comprise several, in particular two, three or four, radial inflow openings in the radial inflow area, which are arranged distributed in the circumferential direction and are separated from one another by support sections running in the axial direction.

Hereby disclosed and claimed both in combination and independently is a pump unit for a turbomolecular vacuum pump or for a vacuum system, with at least one turbomolecular pump stage, which includes rotor blades rotating about an axis of rotation during pumping operation, stator blades that interact with these in a pumping effect, and at least one stator spacer sleeve, which in a radial inflow region comprises several, in particular two, three or four, radial inflow openings, which are arranged distributed in the circumferential direction and are separated from one another by support sections running in the axial direction.

Possible further developments of the turbomolecular pump stage correspond to the further developments for the Holweck pump stage disclosed herein.

Also disclosed and claimed is a turbomolecular vacuum pump with at least one such pump unit and with an outer housing in which the pump unit is accommodated, the outer housing having a radial tap axially at the level of the inflow area of the stator spacer sleeve of the pump unit.

Also disclosed and claimed is a vacuum system with at least one vacuum chamber, at least one such pump unit and at least one recipient to be evacuated, the vacuum chamber comprising a chamber housing as an outer housing in which the pump unit is accommodated and which has a radial one axially at the level of the inflow area of the stator spacer sleeve of the pump unit Has a tap that is in flow connection with the recipient.

Possible further developments of the turbomolecular vacuum pump and the vacuum system each correspond to the further developments for the vacuum pump or for the vacuum system disclosed herein with regard to the Holweck pump stage.

In particular, one or more radial gaps can also be provided for the turbomolecular pump stage, as is disclosed here for the Holweck pump stage.

The invention is described below by way of example with reference to the drawing. Show it: Figs. 1a and 1b each schematically shows a possible pump configuration in which a pump unit according to the invention can be used, Fig. 2 different views of a conventional split-flow vacuum pump, the pump unit of which can be designed according to the invention, Fig. 3 different views of a conventional cartridge vacuum pump, the pump unit of which can be designed according to the invention, Fig. 4 two different views of part of a cartridge vacuum pump according to the invention, Fig. 5a another partial view of the cartridge vacuum pump from Fig. 4 , 5b and 5c possible configurations of the cartridge vacuum pump from Fig. 4 , 6a, 6b and 6c each schematically in a section perpendicular to the axis of rotation different embodiments according to the invention of a pump unit without its own base housing in an independent outer housing, 7a and 7b each schematically in a section perpendicular to the axis of rotation different embodiments according to the invention of a pump unit according to the invention with its own base housing in an outer housing, and 8a and 8b each partially a split-flow vacuum pump in a section running parallel to the axis of rotation according to an exemplary embodiment of the invention.

Fig. 1a shows a pump configuration in which a split-flow vacuum pump 13 is connected to a recipient 53 having several fluidly connected chambers in order to evacuate it. From the perspective of the manufacturer of the vacuum pump 13, the recipient 53 is also referred to as the customer chamber, since in practice it is the pump manufacturer's customers who carry out a respective pumping application with their own recipient 53.

The vacuum pump 13 includes an independent pump housing 41, which may be a so-called box-type housing and is also referred to as an outer housing in the present disclosure. In the pump housing there is a pump unit 11, which includes, among other things, a Holweck pump stage 17 and two turbomolecular pump stages 63 with a common rotor 65 for these pump stages 17, 63.

Each pump stage is assigned a radial tap 43 formed in the outer housing 41, which communicates with an opening 54 of a respective chamber of the recipient 53 during pumping operation.

From the Holweck pump stage 17 is in Fig. 1a For the sake of simplicity, only one Holweck sleeve 21 is shown schematically, while of the turbomolecular pump stages 63 only the rotor blades 68 are shown schematically.

Another pump configuration shows Fig. 1b . There, the customer chamber comprises a recipient 53, again with a plurality of fluidly connected chambers, and a vacuum chamber 51, the recipient 53 and the vacuum chamber 51 having a common housing, of which the outer housing 41, which forms the chamber housing of the vacuum chamber 51, is an integral part. However, it is not mandatory that the outer housing 41 is formed in one piece with the housing of the recipient 53. The common housing can also have several separate sub-housings, which are for one respective pump application can be connected to each other and one of which is the outer housing 41 for the pump unit 11.

The pump unit 11 is located in the vacuum chamber 51 and thus within the outer housing 41. The outer housing 41 of the pump unit 11 is therefore not an independent pump housing in this pump configuration.

The pump unit 11 is a so-called cartridge vacuum pump, which has a base housing 31, which is also referred to as a cartridge sleeve or simply as a pump housing, and in which the individual pump stages of the pump unit 11 are accommodated. In the example shown here, these pump stages are again a Holweck pump stage 17, of which only one Holweck sleeve 21 is shown schematically, and two turbomolecular pump stages 63, of which only the rotor blades 68 are shown schematically. These rotating components 21, 68 of these pump stages 17, 63 are attached to a common rotor 65.

The base housing 31 has an axial suction opening 37, which communicates with one of the chambers of the recipient 53, as well as two radial suction openings 33, which each communicate with a radial tap 43 formed in the outer housing 41 and thus with the associated chamber of the recipient 53.

The two pump configurations according to Figs. 1a and 1b are known per se and serve to explain different situations in which a pump unit 11 according to the invention can be used.

Not shown is a further pump configuration that can also be implemented with a pump unit 11 according to the invention, in which the pump unit 11 in turn has its own base housing 31 and is designed in particular as a cartridge vacuum pump, but in which this pump unit 11 is not as shown in Fig. 1b in a Customer chamber is inserted, but - in this respect as in Fig. 1a - Located in an independent outer housing such as a so-called box-type housing. Such a pump configuration corresponds to the configuration of Fig. 1a , but with the difference that the individual pump stages 17, 63 are located in their own base housing 31 and can therefore be handled as a unit - namely as a pump unit 11 - and can be inserted into an outer housing in order to form an independent split-flow vacuum pump .

An example of a splitflow vacuum pump 13 according to the pump configuration in Fig. 1a is in Fig. 2 shown.

In this example, the outer housing 41 of the vacuum pump 13, which is designed as a box-type housing, has two radial taps 43. A base part 61 of the vacuum pump 13 closes the outer housing 41 on one end face. On this base part 41 there is, among other things, a rotor 65 (see illustration below in Fig. 2 ) of a pump unit 11 rotatably mounted by means of a roller bearing. At its other end, the rotor 65 is rotatably mounted by means of a magnetic bearing. The pump unit 11 comprises a Holweck pump stage 17 and two turbomolecular pump stages 63 arranged at an axial distance from one another. One of the radial taps 43 is located - in relation to the axis of rotation 19 of the rotor 65 - between the two turbomolecular pump stages 63.

The stator parts of the individual pump stages that do not rotate during operation include stator blades 67 of the turbomolecular pump stages 63, a stator section 69 arranged between the two turbomolecular pump stages 63 and Holweck stators 23, 23a. The outer, radially outermost Holweck stator 23 as well as the stator blades 67 and the stator section 69 lie on the inside of the outer housing 41. Located between the two Holweckstators 23, 23a and radially inside the inner Holweckstators 23a each a Holweck sleeve 21, 21a, which are attached to a Holweck hub 20, which in turn is connected to the rotor 65.

The Holweck sleeves 21, 21a and rotor blades 68 of the turbomolecular pump stages 63 rotate together with the rotor 65 during operation.

The Holweck stators 23, 23a are provided with a structure of Holweck webs 25 on each side facing a respective Holweck sleeve 21, 21a in order to form a respective pump-active area. Such an arrangement as shown below in Fig. 2 is shown and which comprises two radially nested Holweck sleeves 21, 21a with associated Holweck stators 23, 23a, is also referred to as a nested Holweck arrangement.

Fig. 2 serves to explain the structure of a possible example of a conventional split-flow vacuum pump and is not according to the invention, since no radial tap is provided in the outer housing 41 for the Holweck pump stage 17 and the Holweck pump stage 17 is not designed according to the invention. Apart from this, a pump unit 11 according to the invention and thus a split-flow vacuum pump according to the invention can be designed as shown in Fig. 2 is shown.

Shows accordingly Fig. 3 an example of a conventional cartridge vacuum pump in which the Holweck pump stage 17 is not designed according to the invention, but otherwise a pump unit 11 according to the invention can have a structure as shown in Fig. 3 is shown.

According to Fig. 3 the cartridge vacuum pump represents a pump unit 11, which not only corresponds to the pump unit 11 Fig. 2 - a common rotor 65 with a Holweck pump stage 17 and two turbomolecular pump stages 63, but also one that accommodates the rotor 65 and these pump stages 17, 63 Base housing 31 includes. The base housing 31 is closed at one end by a base part 61, in which, among other things, the rotor 65 is rotatably mounted by means of a roller bearing. At its other end, the rotor 65 is rotatably mounted by means of a magnetic bearing.

According to the schematic representation in Fig. 1b the base housing 31 is provided with an axial suction opening 37 and two radial suction openings 33. A radial suction opening 33 is located - based on the axis of rotation 19 of the rotor 65 - between the two turbomolecular pump stages 63. The other radial suction opening 33 is located axially at the level of the Holweck pump stage 17.

Together with the rotor 65, the rotor blades 68 of the turbomolecular pump stages 63 and the Holweck hub 20 with the Holweck sleeves 21, 21a attached thereto rotate during the pumping operation. The stationary components of these pump stages 17, 63 are in turn the stator blades 67 of the turbomolecular pump stages 63 and the Holweck stators 23, 23a of the Holweck pump stage 17.

The Fig. 4 and 5a each show a part of a vacuum pump 13 according to the invention, which is designed as a cartridge vacuum pump. Apart from the area of the Holweck pump stage designed according to the invention, which is described in more detail below, this cartridge vacuum pump 13 can have a structure as described above in connection with Fig. 3 has been explained.

Fig. 4 The upper illustration shows a perspective view of a cut made slightly above the base part 61 perpendicular to the axis of rotation 19 of the rotor, the lower illustration in Fig. 4 is a top view of the part of the vacuum pump 13 shown in the upper illustration.

In Fig. 4 Only the outer pump-active area of the Holweck pump stage is shown, which is formed by the outer, radially outer Holweck stator 23 and the outer Holweck sleeve 21. As already explained, the Holweck stator 23 is provided with helically extending Holweck webs 25 on its side facing this rotor sleeve 21. This structure of a Holweck pump area is basically known.

A special feature compared to known Holweck pump stages is that the Holweck stator 23 has an inflow area 26 of great openness, because the inflow area 26 comprises several, in this exemplary embodiment three, radial inflow openings 27, which are distributed in the circumferential direction and separated from each other by support sections 29 running in the axial direction are separated. The support sections 29 are comparatively narrow and therefore have a small circumferential length compared to the inflow openings 27.

The base housing 31 has a corresponding structure. In this axial area of the vacuum pump 13, i.e. axially at the level of the inflow area 26 of the Holweck stator 23, the base housing 31 is also provided with three suction openings 33. Each two successive suction openings 33 in the circumferential direction are separated from one another by a holding section 39 running in the axial direction.

The support sections 29 of the Holweck stator 23 on the one hand and the holding sections 39 of the base housing 31 on the other hand are offset from one another in the circumferential direction, in such a way that one support section 29 is arranged approximately centrally between two holding sections 39 in the circumferential direction.

Furthermore, there is a radial gap 35 between the support sections 29 and the holding sections 39, which results from the fact that the radial outer sides of the support sections 29 lie on a cylinder around the axis of rotation 19, the radius of which is smaller than a cylinder around the axis of rotation 19, on which lie the radial inner sides of the holding sections 39, which each have a reduced radial thickness compared to the axially adjacent regions of the base housing 31, i.e. spring back radially outwards.

Due to this structure, the vacuum pump 13 has an open structure axially at the level of the Holweck pump stage 17 over its entire circumference, which is only interrupted by the comparatively narrow support sections 29 of the Holweck stator 23 and the comparatively narrow holding sections 39 of the base housing 33.

Like the side view of the Fig. 5a shows, the radial suction openings 33 of the base housing 31 have a greater axial height than the radial inflow openings 27 of the Holweck stator 23. However, both the suction openings 33 and the inflow openings 27 each have an elongated shape, that is, the circumferential length of each opening 33, 27 is one Multiple of their respective axial height. Furthermore, the support sections 29 and the holding sections 39 are each comparatively narrow, that is to say the circumferential length of each opening 33, 27 is a multiple of the circumferential length of a respective support section 29 or holding section 39.

How Fig. 5a further shows, the support sections 29 and the holding sections 39 each do not have a constant width over their axial length, but rather they widen in the direction of the axially adjacent areas of the base housing 31 or the Holweck stator 23.

The specific shape, width and radial thickness of the support sections 29 or holding sections 39 are selected in particular in such a way that sufficient mechanical stability is provided, which ensures a sufficient supporting effect and optimal vibration behavior.

In Fig. 5a the Holweck sleeve 21, which interacts with the Holweck stator 23 in a pumping effect, is shown through the radial suction openings 33 of the base housing 31 and the radial inflow openings 27 of the Holweck stator 23.

Holweck bridges, on the other hand, are in Fig. 5a not shown. This is because the Holweck stator 23 according to Fig. 5a according to the exemplary embodiment in Fig. 5c is designed, according to which the Holweck webs 25 are interrupted in the inflow area 26, so that the radial inflow openings 27 of the Holweck stator 23 and also its support sections 29 are free of Holweck webs 25 in this area. However, such a design is not mandatory. Fig. 5b shows an alternative embodiment in which the Holweck webs 25 are not interrupted in the inflow area 26. When designing according to 5a and 5c This results in a difference compared to the design in Fig. 5b even more open design of the inflow area 26.

Although a cartridge vacuum pump 13 according to Fig. 3 and also according to the Fig. 4 and 5a, 5b and 5c are fundamentally functional on their own, such a cartridge vacuum pump is - as already mentioned - inserted into an outer housing in practice. This outer housing has a radial tap in the inflow area 26 of the Holweck stator 23 and thus in the suction area formed by the radial suction openings 33 of the base housing 31, via which a gas to be pumped can reach the Holweck pump stage from a respective recipient.

So that the entire circumference of the Holweck pump stage can be used for the inflow of the gas to be pumped, so that the gas can reach the pump-active area between Holweck stator 23 and Holweck sleeve 21 via all radial inflow openings 27 distributed in the circumferential direction, is the one explained above and in Fig. 4 and Fig. 5a Radial gap 35 shown between Holweck stator 23 and base housing 31 is provided.

An additional measure that further promotes distribution of an input flow in the circumferential direction is shown schematically using the example of a cartridge vacuum pump in Fig. 7b explained. This measure affects the area between the base housing 31 and the outer housing 41. In this area, further measures are also possible, which are also possible with a pump unit 11 without its own base housing, i.e. with a configuration according to Fig. 1a , can be applied. Therefore, these measures will be presented below based on the 6a, 6b and 6c explained using a split-flow vacuum pump 13, which is only shown schematically in a section perpendicular to the axis of rotation 19.

Fig. 6a shows a configuration in which the pump unit does not have its own base housing, but is accommodated in an outer housing 41, which has a radial tap 43 in the area of the Holweck pump stage shown here. The radially outer pump-active area of the Holweck pump stage is formed by the outer Holweck stator 23 and the outer Holweck sleeve 21. On its side facing the Holweck sleeve 21, the Holweck stator 23 is provided with Holweck webs 25.

The Holweck stator 23 has three radial inflow openings 27 distributed in the circumferential direction in the inflow area shown, which are separated from one another by support sections 29.

The outside of the support sections 29 and the inside of the outer housing 41 lie on a common cylinder around the axis of rotation 19.

So that gas flowing in via the radial tap 43 over the entire circumference, i.e. over all three radial inflow openings 27, into the pump-active Area between Holweck stator 23 and Holweck sleeve 21, the outer housing 41 is provided with a recess 47 on its inside in the area of each support section 29. As a result, a flow entering via the radial tap 43 can pass radially on the outside of the support sections 29 and then reach the pump-active area via the next radial inflow opening 27.

The depressions 47 can extend over the entire axial height of the inflow area of the Holweck stator 23 formed by the radial inflow openings 27. A smaller or larger axial extent of the depressions 47 is also possible. The profile of the depressions 47, i.e. their course in the circumferential direction, can in principle be of any design. Producibility that is as simple and cost-effective as possible and optimal flow guidance can form relevant criteria for the design of these depressions 47.

When configured according to Fig. 6b there are no depressions according to 47 Fig. 6a intended. In order to still achieve a distribution of an input flow in the circumferential direction, the support sections 29 are provided with a reduced radial thickness, i.e. they are set back radially relative to the axially adjacent sections of the Holweck stator 23. This creates a channel 24 on the outside of the Holweck stator 23 between the inside of the outer housing 41 and the outside of the Holweck stator 23 formed by the outside of the support sections 29 and thereby a radial gap between the outer housing 41 and the Holweck stator 23. This annular gap formed by the channel 24 can be used a distribution of an inflowing gas can be achieved in the circumferential direction. For such a configuration, machining of the inside of the outer casing 41 is not required.

Alternatively to the measure according to Fig. 6b A circumferential annular gap can be created according to Fig. 6c a circumferential channel 45 on the Inside of the outer housing 41 is formed. A reduction in the radial thickness of the support sections 29 is not necessary with this measure.

Both in connection with Fig. 6b mentioned channel 24 as well as channel 55 Fig. 6c can extend over the entire axial height of the inflow area of the Holweck stator 23 formed by the inflow openings 27. A smaller or larger axial extent of the channel 24 or 55 is also possible.

Combinations of the above using the 6a, 6b and 6c Any measures explained are possible. In addition to a radial reduction of the support sections 29, for example, depressions 47 according to Fig. 6a be provided. Furthermore, for example, in addition to a channel 24 according to Fig. 6b a circumferential channel 45 on the inside of the outer housing 41 according to Fig. 6c be provided, ie the annular gap between the Holweck stator 23 and the outer housing 41 can be formed together by a channel on the outside of the Holweck stator 23 and a channel on the inside of the outer housing 41.

As already mentioned above, the show 7a and 7b each a configuration with a cartridge-type pump unit, which has its own base housing 31 and is inserted into an outer housing 41, which has a radial tap 43 axially in the area of the inflow area of the Holweck stator 23 formed by the inflow openings 27.

The design of this cartridge vacuum pump in the inflow area corresponds to the structure in the Fig. 4 as well as 5a and 5c shown vacuum pump. According to the representations in 6a, 6b and 6c the radially outer Holweck pump area is shown with the outer Holweck stator 23 and the Holweck sleeve 21 assigned to it. The Holweck stator 23 has three in the circumferential direction distributed radial inflow openings 27 and the base housing 31 has three circumferentially distributed radial suction openings 33 which are offset in the circumferential direction relative to the inflow openings 27 of the Holweck stator 23. The inflow openings 27 of the Holweck stator 23 are separated by comparatively narrow support sections 29, while holding sections 39 of the base housing 31 each separate two radial suction openings 33 of the base housing 31 which follow one another in the circumferential direction.

The holding sections 39 of the base housing 33 lie with their outsides on the inside of the outer housing 41. Nevertheless, gas flowing in via the radial tap 43 of the outer housing 41 can be distributed in the circumferential direction, since there are flow paths leading to all three radial inflow openings 27 of the Holweck stator 23. The distribution is favored by the already in connection with the Fig. 4 and 5a explained radial gap 35 between Holweck stator 23 and base housing 31, which is created by a reduction in the radial thickness of the holding sections 39, i.e. by the fact that they spring back radially outwards relative to axially adjacent areas of the base housing 31.

This openness of the overall structure with several radial inflow openings 27 of the Holweck stator 23 and several radial suction openings 33 of the base housing 31 ensures an increase in the suction speed compared to known designs.

A further improvement in the pumping speed can be achieved if according to Fig. 7b according to the already based on Fig. 6c explained embodiment, a circumferential channel 45 is formed on the inside of the outer housing 41, through which a radial gap is created between the base housing 31 and the outer housing 41, via which a gas flowing in through the radial tap 43 can be distributed in the circumferential direction. The radial gap 45 makes it possible that gas can flow past the holding sections 39 of the base housing 31 radially on the outside.

With regard to possible additional or alternative configurations of the embodiments according to 7a and 7b is also referred to above in connection with Fig. 4 , 5a, 5b and 5c as well as 6a, 6b and 6c explained embodiments are referred to. For example, when configuring according to Fig. 7a on the inside of the outer housing 41 recesses corresponding to the recesses 47 Fig. 6a be provided in order to enable flow around the holding sections 39.

The 8a and 8b each show a partial split-flow vacuum pump 13 in a section running parallel to the axis of rotation, with only the radially outer Holweck stator 23 of the Holweck pump stage being shown, which is arranged in an outer housing 41 designed as a box-type housing, which has radial Taps 43 are provided. The 8a and 8b serve, among other things, to illustrate different courses of the radial inflow openings 27 of the Holweck stator 23, as have already been mentioned elsewhere.

Accordingly Fig. 5c Here, the Holweck webs 25 are interrupted in the inflow area of the Holweck stator 23, so that the radial inflow openings 27 of the Holweck stator 23 and also its support sections 29 are free of Holweck webs 25 in this area.

Accordingly Fig. 6c Here, a circumferential channel 45 is formed on the inside of the outer housing 41 in order to achieve a distribution of an input flow entering through the radial tap 43 in the circumferential direction.

The two embodiments of the 8a and 8b differ in that according to Fig. 8a the radial inflow openings 27 lie on a circle around the axis of rotation 19, the radius of which is perpendicular to the axis of rotation 19, while according to Fig. 8b the radial inflow openings 27 lie on a helix around the axis of rotation 19, the direction of rotation of the helix being opposite to that of the course of the Holweck webs 25. The direction of rotation of the helix and the direction of rotation of the course of the Holweck webs 25 can alternatively be the same. Alternatively, the radial inflow openings can also lie in a plane inclined relative to the axis of rotation 19. The channel 45 on the inside of the outer housing 41 follows the course of the inflow openings 27, so in these embodiments it lies on a circle around the axis of rotation 19 ( Fig. 8a ) or on a helix around the axis of rotation ( Fig. 8b ).

Both courses - so on a circle according to Fig. 8a and on a helix according to Fig. 8b - Can also be provided with a Holweck stator 23, in which corresponding Fig. 5b the Holweck bridges 25 are not interrupted.

Reference symbol list

11

Pump unit

13

vacuum pump

15

Vacuum system

17

Holweck pump stage

19

Axis of rotation

20

Holweck hub

21

Holweck sleeve

21a

Holweck sleeve

23

Holweck stator

23a

Holweck sleeve

24

channel

25

Holweck Bridge

26

Inflow area

27

Radial inflow opening of the Holweck stator

29

Support section of the Holweck stator

31

Basic housing

33

radial suction opening of the base housing

35

Radial gap

36

channel

37

axial suction opening of the base housing

39

Holding portion of the base housing

41

Outer casing, pump casing

43

radial tap

45

channel

47

deepening

51

vacuum chamber

53

recipient

54

opening

55

Radial gap

61

Base part

63

Turbomolecular pumping stage

65

rotor

67

Stator blade

68

Rotor blade

69

stator section

Claims (15)

Pump unit (11) for a vacuum pump (13), in particular a turbomolecular vacuum pump, or for a vacuum system (15). - at least one Holweck pump stage (17), which comprises one or more Holweck sleeves (21) rotating around an axis of rotation (19) during pumping operation and one or more Holweck stators (23), each of which has at least one Holweck web on a side facing a Holweck sleeve (21). (25), wherein the Holweck stator or - in the case of several Holweck stators - the outer, most radially outer Holweck stator (23) in an inflow area (26) comprises several, in particular two, three or four, radial inflow openings (27), which are arranged distributed in the circumferential direction and through Support sections (29) extending in the axial direction are separated from one another. Pump unit (11) according to claim 1, wherein the radial inflow openings (27) each have an elongated shape. Pump unit according to claim 1 or 2, wherein the radial inflow openings (27) on a circle around the axis of rotation (19) or in a plane inclined with respect to the axis of rotation or on a curve running around the axis of rotation (19) with a gradient different from zero, in particular on a helix. Pump unit according to one of the preceding claims, wherein the support sections (29) are each designed as a web or strut, in particular wherein the support sections (29) each extend over one in the circumferential direction Angles in the range from 3° to 30°, in particular from 5° to 20°, in particular over an angle of 10°. Pump unit according to one of the preceding claims, wherein the radial inflow openings (27) and/or the support sections (29) are at least partially free of Holweck webs. Pump unit according to one of the preceding claims, wherein the Holweck pump stage (17) is surrounded by a base housing (31) which has at least one radial suction opening (33) axially at the level of the inflow area (26) of the Holweck stator (23). Pump unit according to claim 6, wherein a radial gap (35) running around the axis of rotation (19) is formed axially at the level of the inflow area (26) of the Holweck stator (23) between the Holweck stator (23) and the base housing (31). Pump unit according to claim 6 or 7, wherein the base housing (31) axially at the level of the inflow area (26) of the Holweck stator (23) has several, in particular two, three or four, distributed in the circumferential direction and separated by holding sections (39) extending in the axial direction separate radial suction openings (33). Pump unit according to one of claims 6 to 8, wherein the number of radial inflow openings (27) of the Holweck stator (23) is equal to the number of radial suction openings (33) of the base housing (31), and / or wherein the support sections (29) of the Holweck stator (23) and the holding sections (39) of the base housing (31) are offset from one another in the circumferential direction. Pump unit according to one of claims 6 to 9, wherein the radial suction openings (33) of the base housing (31) each have an elongated shape and extend around the axis of rotation (19), and / or wherein the radial suction openings (33) of the base housing ( 31) lie on a circle around the axis of rotation (19) or in a plane inclined with respect to the axis of rotation or on a curve running around the axis of rotation (19) with a slope different from zero, in particular on a helix, and / or
wherein the holding sections (39) of the base housing (31) are each designed as a web or strut, in particular wherein the holding sections (39) each extend in the circumferential direction over an angle in the range from 3° to 30°, in particular from 5° to 20° , especially over an angle of 10°. Vacuum pump (13), in particular turbomolecular vacuum pump, with at least one pump unit (11) according to one of the preceding claims and with an outer housing (41) in which the pump unit (11) is accommodated, the outer housing (41) being axially at the level of the inflow area ( 26) of the Holweck stator (23) of the pump unit (11) has a radial tap (43). Vacuum system (15) with at least one vacuum chamber (51), at least one pump unit (11) according to one of claims 1 to 10, and at least one recipient (53) to be evacuated,
wherein the vacuum chamber (51) comprises a chamber housing as an outer housing (41), in which the pump unit (11) is accommodated and which has a radial tap (43) axially at the level of the inflow area (26) of the Holweck stator (23) of the pump unit (11). which is in flow connection with the recipient (53). Vacuum pump (13) according to claim 11 or vacuum system (15) according to claim 12, wherein between the outer housing (41) on the one hand and the Holweck stator (23) or the base housing (31) on the other hand axially at the level of the radial tap (43) of the outer housing ( 41) there is a radial gap (55) running around the axis of rotation (19). Vacuum pump (13) or vacuum system (15) according to claim 13, wherein the radial gap (55) is at least partially formed by a channel (45) formed on the inside of the outer housing (41) and/or by one on the outside of the Holweck stator ( 23) or the base housing (31) formed channel (24, 36) is formed. Vacuum pump (13) or vacuum system (15) according to claim 13 or 14, wherein the outer housing (41) is preferred at least in the area of one of the support sections (29) of the Holweck stator (23) or a holding section (39) of the base housing (31). in the area of each support section (29) or holding section (39), has a recess (47) on its inside.

Images