JP2012514149A - Vacuum pump - Google Patents

Abstract

The invention relates to a vacuum pump, in particular a Holweck vacuum pump, comprising a pump housing (34) in which rotor elements (24, 36) are arranged. The rotor element has at least two cylindrical conveying elements (24). The conveying elements (24) are arranged concentrically with each other and connected to a disc-shaped holding element (36). A stator element (26) is arranged between two adjacent transport elements (24). According to the invention, a single spiral channel (28) is formed by the stator element.

Description

  The present invention relates to a vacuum pump, and in particular to a Holweck vacuum pump.

  The vacuum pump includes a rotor element disposed in the pump housing. In the Holweck vacuum pump, the rotor element has a tubular conveying element, for example arranged concentrically on the rotor shaft. The conveying element is surrounded by a stator element having a spiral flow path. Due to the rotation of the transport element, the transport mechanism of the friction vacuum pump acts to transport the gas molecules to be transported. Due to the rotational movement, the face of the conveying element facing towards the stator element transmits pulses to the individual gas molecules. The performance of such a friction vacuum pump is largely determined by the relative speed between the friction surfaces and the type of gas to be conveyed.

  A specially designed Holweck vacuum pump is described in DE 19632375. The rotor element of the Holweck vacuum pump described in this document comprises a disc-shaped holding element connected to the rotor shaft. The holding element is surrounded by a plurality of tubular conveying elements concentrically with the rotor shaft. Therefore, adjacent transport elements form one annular flow path. Stator elements are respectively disposed in these flow paths. Each stator element comprises a tubular wall that closes itself and extends parallel to the conveying element. On both sides of the tubular wall, helical webs are respectively arranged so that each stator element forms two helical channels. Accordingly, two flow paths are formed between two adjacent tubular conveying elements. In such a structure, one side wall of the flow path is always formed by the conveying element, and the other three side walls of the flow path are formed by the stator element.

German Patent Application No. 19632375

  The present invention aims at simplifying the design of the vacuum pump, in particular the Holweck vacuum pump, so as to enable a particularly advantageous production in particular economically and / or to increase the conveying capacity.

  According to the invention, the above object is achieved by the features defined in claim 1.

  The vacuum pump according to the invention, in particular a Holbaek vacuum pump, comprises a rotor element which is arranged in a pump housing and is preferably supported on a rotor shaft. The rotor element comprises at least two transport elements, which according to the first preferred embodiment of the invention are arranged concentrically with one another and are tubular. In this embodiment, it is particularly preferable that the tubular conveying element is arranged concentrically with respect to the rotor shaft. Here, the gas is transported by the friction generated on the side surfaces of the transport element, which transports the gas particles. A stator element is formed between two adjacent transport elements. The stator element includes a spiral channel through which the medium is transported in the transport direction. The medium is transported by relative movement of the stator element and the rotor element or the transport element of the rotor element. In the process, the rotor element connected to the rotor shaft is normally rotated. However, the stator element can also be rotated, in particular both the stator element and the rotor element can preferably be rotated in opposite directions.

  According to the invention, the stator element comprises a single spiral channel.

  Thus, in contrast to German Offenlegungsschrift 19632375, only one channel, not two channels, is arranged radially between two adjacent conveying elements. Thus, the stator element does not comprise a central tubular wall with a helical web. Unlike the central tubular wall with a spiral web, the stator element of the present invention is preferably a free-standing flat spiral band. Optionally, a stabilizing web can be further provided, but not separated into two separate channels.

  Thus, according to the invention, a single spiral channel is arranged radially between two adjacent transport elements. It is also possible to provide a plurality of flow paths parallel to each other in the transport direction and the axial direction so that a spiral flow path having a plurality of threads is provided.

  It is preferred that the two lateral surfaces of the flow path are formed by two adjacent transport elements. Therefore, it is preferable that the radial width of the flow path substantially corresponds to the distance between two adjacent transport elements.

  Due to the inventive design of the flow path, if the cross-sectional area of the flow path is the same, the transport capacity becomes larger under the precondition that the other limit conditions are also the same. This is evident from a comparison between the schematic diagrams represented in FIGS.

  According to the current technology (FIG. 1), the flow path 10 is formed by the stator element 12, and the three lateral surfaces 14, 16, 18 are formed by the fixed stator element 12. A fourth inner surface 20 of the flow path 10 is formed by a rotating tubular conveying element 22. The velocity distribution v in the vertical direction in the plane of the drawing is schematically shown below the schematic diagram. Considering in a simple way, ie ignoring the “slip flow” condition, the velocity distribution is approximately linear, as shown in the chart. The speed is zero on the side face 16 of the flow path 10 and is maximum on the inner face 20 of the conveying element 22. This speed substantially corresponds to the tangential speed of the rotating transport element 22. Under the precondition that compression is K = 1, the volume of gas delivered is proportional to the surface area and the integral over velocity.

  According to a first preferred embodiment of the invention, two mutually concentric tubular conveying elements 24 are provided. A helical stator element 26 is arranged between the two conveying elements 24. The flow path 28 is thus formed on the one hand by two fixed inner walls 30 of the stator element 26 and on the other hand by two moving inner walls 32 of the conveying element 24. As shown in the diagram of FIG. 2, the velocity distribution v in the vertical direction in the plane of the drawing is represented so that the velocity is maximum at the two inner walls 32. Considered in a simple way, the velocity distribution is again linear here. Therefore, simply expressed, the surface area under the curve is twice the surface area based on the velocity distribution according to the current technology.

  In the two charts, the somewhat difficult to understand speed transition is represented by broken lines. However, from the speed transition, it is clear that the transport volume (surface area under the curve) in the structure according to the present invention (FIG. 2) is considerably larger than the structure according to the current technology (FIG. 1).

  According to a preferred embodiment, the rotor element comprises a preferably disc-shaped holding element connected to the rotor shaft. At least two tubular conveying elements are connected to the holding element. In this context, it is preferred that the holding element has a preferably annular projection that can be attached to or inserted into the transport element. The conveying element is connected to the holding element by press fitting, bonding or the like.

  The transport element is preferably arranged only on one side of the holding element, and the holding element is particularly preferably provided on the upstream side of the transport element when viewed in the transport direction. This has the advantage that the holding element can further comprise a rotor blade for conveying the gas to be pumped towards the conveying element.

  In order to realize as small a vacuum pump as possible, it is advantageous to arrange an additional flow path between the outer conveying element and the inner wall of the pump housing. In this case, a corresponding additional stator element can be directly connected to the pump housing or formed integrally with the pump housing.

  Furthermore, the inner conveying element can be replaced directly by the outer surface of the rotor shaft.

  According to a particularly preferred embodiment, the conveying element and / or the holding element, i.e. preferably the entire rotor element, are made of a very stable material while being lightweight. In particular, it is possible to make components of plastic, preferably carbon fiber reinforced plastic (CFRP). Thereby, the manufacturing costs can be significantly reduced. Furthermore, the use of such lightweight components has the advantage that the resulting moment of inertia is significantly reduced. Therefore, the structure of the bearing, in particular a magnetic bearing, can be simplified. This is a further cost reduction.

  According to a second preferred embodiment of the invention, a disc-shaped transport element is provided instead of a tubular transport element. Such at least two disc-shaped conveying elements are preferably arranged substantially parallel to each other and, according to a particularly preferred embodiment, extend substantially radially with respect to the rotor shaft. According to a first preferred embodiment, the stator element is arranged between two adjacent conveying elements and has a single helical flow path that can itself be designed to have a plurality of threads. I have. The transport principle corresponds to the transport principle described with respect to the first embodiment, and the gas is transported in a substantially radial direction. In this connection, it is particularly preferred that the rotor shaft is formed as a hollow shaft, preferably with an axial flow path. In this case, the gas is transported by, for example, taking in the gas through a flow path formed through the rotor shaft and passing the gas through a spiral flow path disposed between adjacent transport elements. It can be carried out by conveying to the outside in the radial direction. Also, the reverse transport direction is possible. Further, for example, the gas is preferably conveyed alternately between the radially inner side and the radially outer side through adjacent flow paths so that a meandering flow is formed when viewed in cross-section. Is possible.

  A normally gaseous fluid is conveyed by the relative movement of the rotor and stator elements. In particular, the relative movement between the rotor element and the stator element is a relative movement of the conveying element of the rotor element relative to the stator element. According to a preferred embodiment, the stator element is fixed so that it is driven only by the rotor shaft, and therefore does not move.

  However, in the embodiment described above, the components described as rotor elements are fixed, so that a stator element that does not move and forms a spiral or spiral flow path is used, for example, with the stator element as a drive shaft. It is also possible to drive by connecting.

  Furthermore, both the rotor element and the stator element are arranged to be driven and can be connected, for example, to a corresponding drive shaft. By rotating the rotor element in the opposite direction relative to the stator element, a relative movement in which the fluid is conveyed is generated.

  The invention will now be described by means of preferred embodiments of the invention with reference to the accompanying drawings.

It is a basic schematic diagram showing a part of a vacuum pump according to the current technology. It is a basic schematic diagram showing a part of the vacuum pump according to the first preferred embodiment of the present invention. 1 is a schematic perspective cross-sectional view showing a Holvec stage of an inventive vacuum pump according to a first preferred embodiment of the present invention. 1 is a schematic perspective view showing a stator element according to a first preferred embodiment of the present invention. It is a schematic sectional drawing which shows the 2nd preferable embodiment of this invention. FIG. 3 is a schematic cross-sectional view showing a spiral stator element.

  A rotor element constructed in accordance with the present invention is disposed in the pump housing 34 (FIG. 3). The rotor element includes a substantially disc-shaped holding element 36. The holding element 36 is connected to a rotor shaft (not shown) by a central pin 38. For illustration purposes, the rotor shaft centerline 58 is shown. An inner region of the disc-shaped holding element 36 is formed as a closed disc 40. A closed disk 40 follows the radial rotor blades 42. An annular projection 46 is arranged on the bottom side of the holding element 36 facing the transport direction 44, and the projection 46 is preferably formed integrally with the holding element 36.

  In the illustrated embodiment, three tubular or cylindrical conveying elements 24 are intimately connected to the projection 46 by plug-in attachment. Accordingly, the transport element 24 is rotated by the rotation of the holding element 36. Stator elements 26 designed according to the invention are arranged between two adjacent transport elements 24, respectively, and in the illustrated embodiment, two stator elements 26 are provided.

  As can be seen in particular from FIG. 4, the stator element 26 is helical. In this configuration, a single helical element can be provided, or a plurality of helical elements arranged inside each other can be provided. In the embodiment of the stator element 26 illustrated in FIG. 4, a total of five interengaging stator members 52 are provided, each of which is formed as a partial helical element. A spiral flow path is formed between each adjacent stator member 52, and when a plurality of mutually engaging stator members 52 are provided, a plurality of parallel extending in the transport direction or the axial direction. The flow path is provided. The functionality of the individual channels 28 can be seen in FIG.

  Accordingly, the stator element 26 shown in FIG. 4 includes a plurality of flow paths 28 arranged parallel to each other in the axial direction or the conveying direction 44. However, as described with reference to FIG. 2, the flow paths 28 do not overlap in the radial direction so that a considerably large transfer volume of approximately twice can be obtained.

  In the illustrated embodiment (FIG. 3), an additional flow path 48 is provided between the outer transport element 24 and the pump housing 34. The additional flow path 48 is formed by a similar helical additional stator element 50, which in the illustrated embodiment is tightly connected to the inner wall 54 of the pump housing 34. Or formed integrally with the pump housing 34.

  The medium conveyed through the individual channels 28, 48 is ejected through the openings 56 or supplied to a further conveying stage. Furthermore, it is possible to provide a common discharge port between the adjacent flow paths 28 and 48.

  In a further preferred embodiment (FIG. 5), the inventive transport principle described with reference to FIG. 2 is in principle also realized here. However, the conveyance of the gas with respect to the longitudinal axis 58 of the rotor shaft 60 is performed in the radial direction.

  A rotor shaft 60 is arranged inside a schematically illustrated pump housing 62, and in the illustrated embodiment, the rotor shaft 60 is configured as a hollow shaft. A disc-shaped transport element 64 is connected to the hollow shaft 60. Here, the conveying element 64 surrounding the rotor shaft 60 can be fixed by a protrusion 66, and the protrusion 66 has an annular shape and is connected to the outer surface of the hollow shaft 60. A channel 28 is formed between two adjacent disc-shaped transport elements 64. A stator element 68 is disposed in the flow path 28. In the second preferred embodiment (FIG. 5), the stator element 68 has a spiral shape instead of a spiral shape, so that the flow path also has a spiral shape and extends in the radial direction. Thus, in the embodiment illustrated in FIG. 5, the gas is conveyed in a spiral in the flow path 28, that is, from the inside to the outside.

  In the preferred variant shown in FIG. 5 of the second embodiment of the invention, the inlet 70 of the pump housing 62 in the direction of arrow 72 so that the medium to be transported enters the inner chamber 74 of the hollow shaft 60. Sucked through. Gas is conveyed from the internal chamber 74 through the opening 76 of the hollow shaft 60 into the flow path 28 as indicated by the arrows. The gas is discharged in the direction of arrow 81 through the discharge port 78 of the pump housing 62.

  In the illustrated embodiment, an additional stator element 82 is disposed on the inner wall 80 of the pump housing 62 and is preferably fixedly connected to the pump housing 62 or integrally formed with the pump housing 62. Thereby, the gas is also transported between the two outer transport elements 64 and the inner wall 80 of the pump housing 62.

  The hollow shaft 60 is supported by a shaft journal 86 connected to the drive unit 84.

  The stator element 68 is formed in a spiral shape. Therefore, the stator element 68 can form individual channels extending from the inside to the outside in FIG. 5, for example. Furthermore, it is possible to design a spiral stator element 68 as schematically shown in the cross-sectional view of FIG. The spiral stator element 68 shown in FIG. 6 has a plurality of threads, and in the illustrated embodiment, three channels 88 extend parallel to each other. In the illustrated embodiment, the inlets of the channels are regularly arranged, and when there are three channels, the inlets of the channels are shifted from each other by 120 °.

Claims (14)

A rotor element (36, 24, 64) disposed in the pump housing (34, 62) and connected to the rotor shaft (58) and having at least two conveying elements (24, 64);
A vacuum pump with a stator element (26,68) arranged between two adjacent transport elements (24,64) and having a single spiral or spiral channel (28), in particular In the Holweck vacuum pump,
The rotor shaft (58) is designed as a hollow shaft (60), whereby the gas to be transported is at least partially transported through the hollow shaft (60) .   The vacuum pump according to claim 1, characterized in that the transport elements (64) have a disk shape and are arranged substantially parallel to each other.   The vacuum pump according to claim 2, wherein the transport element (64) extends in a substantially radial direction with respect to the rotor shaft (58).   4. An axial side surface (65) of the spiral channel (28) is formed by two adjacent transport elements (64). Vacuum pump.   The vacuum pump according to any one of claims 1 to 4, wherein the width of the flow path corresponds to a distance between two adjacent transport elements (24, 64). Said rotor element (36) preferably comprises a disc-shaped holding element (36),
The holding element (36) is connected to the rotor shaft and has the transport element (24) connected to the rotor shaft. Vacuum pump.   The holding element (36) preferably has an annular projection (46), which is connected to the projection (46) by insertion or plug-in attachment. 7. A vacuum pump according to claim 6, comprising an element (24).   The holding element (36) is provided on the upstream side of the transport element (24) when viewed in the transport direction (44), and preferably for transporting gas toward the transport element (24). 8. A vacuum pump according to claim 6 or 7, characterized in that it has a rotor blade (42).   A plurality of, preferably at least two of said conveying elements (24) are provided, arranged in concentric relation to each other, said stator element (26) having a single helical channel (28), 9. A vacuum pump according to any one of the preceding claims, characterized in that it is arranged between the conveying elements (24).   Further comprising an additional flow path (48) disposed between the outer conveying element (24) and the inner wall (54) of the pump housing (34), the corresponding additional stator element (50) comprising: 10. A vacuum pump according to any one of the preceding claims, preferably connected to the pump housing (34).   11. The holding element (36) and / or the conveying element (24) and / or the hollow shaft (60) are made of carbon fiber reinforced plastic. Vacuum pump.   The stator element (26, 68) comprises a single spiral or spiral channel (28) having a plurality of threads. Vacuum pump.   The medium to be transported in the flow path (28) is transported by relative movement between the rotor element (36, 24, 64) and the stator element (26, 68). Item 13. A vacuum pump according to any one of Items 1 to 12.   14. The rotor element according to claim 1, wherein the rotor element is supported on a rotor shaft (58), preferably driven by an electric motor, and the stator element (26, 68) is preferably fixed. The vacuum pump according to crab.

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