EP3280916B1 - Vacuum-pump rotor - Google Patents

Description

The invention relates to a vacuum pump rotor, in particular a rotor for a turbo-molecular vacuum pump.

Vacuum pumps, such as turbo-molecular vacuum pumps, have a rotor on a rotor shaft. The rotor shaft is driven by an electric motor. The blades of the rotor interact with stator disks, which are usually fixed in a pump housing. In the case of high-speed rotors, such as those used in particular in turbo molecular pumps, it is known to manufacture rotors from aluminum, steel or corresponding alloys. To achieve a high vacuum of, in particular, less than 10 ^-4 mbar, the rotors must be operated at high rotational speeds. A limit when using rotors made of steel, aluminum or the like is the tip speed of the rotor blades, ie the tangential speed occurring at the blade tips. With known rotors, a tip speed of 400 m / s can be achieved. The conveyance of light gases, such as helium or hydrogen, is also problematic here, since these have a high thermal speed and high rotational speeds of the rotors, ie in particular a high tip speed, are required for conveying.

The document WO 2005/001294 A1 discloses in Fig. 5 a vacuum pump rotor according to the preamble of claim 1. The object of the invention is to create a vacuum pump rotor with which a high tip speed can be achieved.

The object is achieved according to the invention by the features of claim 1.

The vacuum pump rotor according to the invention has a hub element which can be connected to the shaft of the vacuum pump or which forms the shaft. Rotor blades that are set at an angle are connected to the hub element.

To increase the tip speed according to the invention, the rotor elements and / or the hub element have several layers of material. This makes it possible to provide different materials during operation in heavily used areas by arranging material layers made of different materials. It is particularly preferred here that at least one of the material layers comprises fiber-reinforced material. In particular, by providing at least one material layer with fiber-reinforced material, it is possible to operate vacuum pump rotors at higher speeds. In particular, it is possible in this way to achieve a tip speed of more than 400 m / s, in particular more than 500 m / s and particularly preferably more than 600 m / s.

The vacuum pump rotor has a hub element for connection to a rotor shaft, wherein the rotor shaft can also be formed by a plurality of hub elements. A plurality of rotor blades surrounding the rotor element are connected to the rotor element. According to the invention, the rotor blades each have a wing root connected to the hub element and a wing head connected to the latter. According to the invention, the hub element has at least one retaining element comprising fiber-reinforced material. A base element is connected to the retaining element of the hub element, the base element forming the wing root and the wing head. In particular, the connection between the holding element and the base element takes place in such a way that these two elements partially overlap, so that in this way at least two material layers are formed. In this case, at least one of the two elements has fiber-reinforced material, it being preferred that both elements have fiber-reinforced material. With such a structure, high loads on the vacuum pump rotor and, in particular, a high tip speed can be achieved.

In particular, through the preferred developments of the invention described below, it is possible to manufacture vacuum pump rotors that can withstand high loads. As a result, high-speed vacuum pump rotors can be manufactured. Here it is possible to reduce the diameter of the vacuum pump rotors, since the required tip speed of in particular more than 400 m / s can be achieved due to the possible increase in the speed.

The hub element preferably has two opposing holding elements, a hub part of the base element being arranged between the two holding elements. To this extent, a three-layer structure is implemented in this area, it again being preferred that both hub elements and / or the hub part are made of fiber-reinforced material. The entire base element is preferably made of fiber-reinforced material.

According to the invention, a stiffening element is provided, which preferably comprises fiber-reinforced material. The at least one stiffening element is flatly connected to the retaining element of the hub element, the stiffening element simultaneously also protruding into the wing root of the respective rotor blade. The stiffening element thus forms a further layer of material. It is particularly preferred that two stiffening elements are provided which are connected to the base element, in particular the hub part of the base element, on opposite sides. That In a particularly preferred embodiment, the base element represents a middle layer of material, with a stiffening element which protrudes into the wing root and is flatly connected to the base element is arranged opposite one another at least in the area of the hub part. In a special embodiment, two further material layers are provided by the two holding elements, which in turn are arranged on the outside of the stiffening elements and form an essential part of the hub element. The two holding elements are arranged opposite one another and are preferably connected directly or indirectly to the respective upper conductors of the stiffening elements over a large area. To further improve the load-bearing capacity of the rotor blade, it is possible to provide further intermediate layers, in particular made of different materials and / or with different orientations of fibers.

In addition, the at least one, in particular both, stiffening elements can have a fixing element on an inner side. The fixing element is preferably designed as an axially extending shoulder. This preferably engages behind the respective holding element in the radial direction.

According to the invention, at least one additional wing element is formed which also has fiber-reinforced material. The at least one additional wing element is directly or indirectly connected to the holding element. Furthermore, the additional wing element is preferably connected directly or indirectly to the wing root and / or the hub part of the base element. The additional wing element can also be connected to the wing head, in particular over a large area. It is preferred here that the additional wing element is designed to be flat as a further material layer.

The additional wing element also has a fixing element on an inner side, which in turn can partially extend axially in accordance with a shoulder and / or engage behind the holding element, in particular radially.

Again, it is preferred to provide two additional wing elements in this embodiment as well, which are arranged on different sides of the base element, a symmetrical structure in particular being preferred in which the base element forms the center plane.

In a further preferred embodiment of the vacuum pump rotor, a further layer of material is provided. Here, the additional wing element is designed as an inner additional wing element and at least one further outer additional wing element is provided. This is preferably connected flatly to the inner additional wing element, it being particularly preferred that the outer dimensions of the two additional wing elements are identical. If necessary, however, the outer additional wing element can also cover only part of the inner additional wing element. It is also possible for the outer dimensions of the inner additional wing element to be smaller than those of the outer additional wing element. For example, the outer additional wing element can extend into the wing head and possibly even completely cover it, the inner additional wing element being arranged only in the area of the wing root and / or possibly only covering parts of the wing head.

Preferably, the base element and at least one, preferably all, additional wing elements have essentially the same outer contour, in particular a wing outer contour.

According to the invention, the at least one stiffening element rests flat against the base element and one of the additional wing elements in the area of the wing root and the stiffening element is firmly connected to these. Furthermore, it is preferred that the inner additional wing element in the area of the wing root or the wing head lies directly flat on the outer additional wing element and is preferably connected to it. The structure of the individual rotor blades and also of the hub element is preferably multilayered in such a way that the structure is symmetrical to the base element.

A usually ring-shaped hub element preferably has a plurality of, in particular, pitched rotor blades on the circumference. To increase the tip speed according to the invention, the hub element and / or the rotor blades have fiber-reinforced material. In this case, the fibers are preferably arranged to a large extent in accordance with the load. As a result, the vacuum pump rotors according to the invention can be operated at higher speeds. In particular, it is possible in this way to achieve a tip speed of more than 400 m / s, in particular more than 500 m / s and particularly preferably more than 600 m / s.

The material used is preferably a long fiber-reinforced material with fiber lengths of 1 to 50 mm or continuous fibers with lengths over 50 mm.

The arrangement of the fibers in accordance with the load is preferably carried out by a suitable alignment of the fibers so that they can absorb the forces and moments that occur at such high speeds. An arrangement that is suitable for the load is also achieved by additionally varying the direction, the density, the strength and / or the thickness of the fibers used, depending on the type of load. This is particularly dependent on the area of stress on the hub element and / or on the rotor blades. Furthermore, it is particularly preferred that for an arrangement that is suitable for the demands also for Particularly suitable fibers are used for the corresponding stress.

It is preferred here that metal, plastic or carbon fibers are used. Here it is again preferred to use metal fibers in the area of the hub element or the part of the rotor blades facing the hub element, since they have a different breaking behavior.

Solid metal or plastic parts can also be incorporated into the laminate in the hub area to stabilize the position of fibers or to create volume. It is also preferred that, for example, plastic, carbon and / or metal fibers are impregnated or pre-impregnated. Impregnation with epoxy resin, phenolic resin, bismaimides and / or thermoplastics, but also with polyurethane, is preferred here. Furthermore, it is preferred to arrange the fibers as a woven fabric, as a spread tow, as a tape layer, as a TFP (tailored fiber placement), wound, braided and / or as a spiral fabric. Furthermore, in particular, mixed forms of different fiber arrangements appropriate to the load are possible and also preferred.

To achieve particularly high tip speeds, it is preferred that at least 20%, preferably at least 30% of the fibers provided in or on the hub element and / or in or on the rotor blades are arranged in accordance with the load, ie in particular in the main stress direction. In the wing area, the fibers preferably run in a radial direction in order to absorb the forces. In the hub area, parts of the fibers are preferably placed purely in the circumferential direction, but other areas have different directions in order to enable tension to be shifted. The fiber volume fraction based on the total volume of the hub element and / or the rotor blades is preferably greater than 50%, in particular greater than 60%.

The fibers arranged in or on the hub element are preferably arranged essentially in the circumferential direction, i.e. in the direction of rotation of the hub element. Here, the fibers are preferably arranged in such a way that the fibers can absorb the forces in the circumferential direction. Here, based on the circumferential direction, a deviation in an angular range of ± 10 ° to ± 20 ° is defined in such a way that this is still a question of fibers which run essentially in the circumferential direction.

The fibers preferably run essentially radially in or on the rotor blades. In the area of the wings, the fibers must be arranged in such a way that the fibers absorb the forces in the radial direction. A deviation in the range of ± 10 ° to ± 20 ° further defines a fiber that runs essentially radially.

In particular in the adjusted area of the wing parts of the rotor blades, it is preferred to additionally use crossing fibers in order to arrange the fibers in accordance with the load, for example against twisting of the blades. The fibers preferably run in an angular range of ± 30 ° to ± 45 ° with respect to the longitudinal axis of the wing and ± 70 ° to ± 90 ° to one another. Corresponding fiber layers, such as patches or spread tows, are suitable here. In a transition area between the hub elements and the rotor blades, it is particularly preferred that fibers pass from the hub element into the rotor blades, so that the connection area between the hub element and the rotor blades is designed as load-bearing as possible. In particular with such a construction, it is preferred that the hub element and the rotor blades are formed in one piece. However, it is also possible for the rotor blades to be connected to the hub by hanging them, inserting them into corresponding grooves and the like. Combinations of these are also possible, so that they are initially suspended or connected to the hub element in some other way Wing elements are then connected to the hub element via a fiber layer in this area.

The fibers can be connected by subsequent casting, resinification or the like. First, however, the fibers can also be glued to one another in order to define an exact position of the fibers. The fibers can also be fixed or connected to one another in the required direction by embroidery, knitting or the like.

Furthermore, it is preferred that the rotor blades can have an angle of attack of 8 ° -50 °.

With the aid of the vacuum pump rotors described above, it is possible in particular to achieve a high tip speed of more than 400 m / s, in particular more than 500 m / s and particularly preferably more than 600 m / s. This has the advantage, which is essential to the invention, that the rotors are also suitable for conveying light gases, such as, in particular, helium and hydrogen. This also makes it possible to implement pump rotors with smaller diameters at high delivery rates.

It is particularly preferred that one of the additional wing elements, in particular both the inner and the outer additional wing elements, have a radial layer made of a fiber-reinforced material, in particular fiber-reinforced plastic. Furthermore, it is preferred that one of the additional wing elements, in particular the two outer additional wing elements, have a spreadtow fabric layer.

The at least one stiffening element preferably also has fiber material, in particular plastic fiber material. Some of the fibers here preferably run in the circumferential direction. As a result, a tangential layer is formed. It is preferred that the at least one holding element also has fibers that run in the circumferential direction, see above that further tangential layers are formed. The additional inner wing elements, in particular, have fibers running radially as the main fiber direction in a preferred embodiment, so that radial layers are formed as a result. In the case of the two outer additional wing elements which are preferably provided, the fibers are arranged crossed with respect to one another and, in particular, a spreadtow fabric is provided. In particular, the multi-layer design of the vacuum pump rotor from preferably different material layers with particularly preferred different orientations of the material fibers makes it possible to manufacture vacuum pump rotors that withstand extremely high loads so that very high tip speeds can be achieved.

The construction of vacuum pump rotors described above is also possible for other rapidly rotating rotors, such as those used in the field of blowers, ventilators, gas conveying, but this is not part of the invention.

The invention is explained in more detail below on the basis of a preferred embodiment with reference to the accompanying drawing.

The figure shows a section of a vacuum pump rotor in the assembled state and partially as an exploded view, the representation being made in a schematically simplified manner.

In the figure, a part of a multi-layer vacuum pump rotor with interconnected layers of material is initially shown schematically. Part of a hub element 10 is shown here. Here, only one circular ring segment of the circular ring-shaped hub element 10 is shown. The hub element 10 surrounds, for example, a rotor shaft to which it is firmly connected. Usually, several such annular hub elements are arranged one behind the other in the axial direction, so that several vacuum pump stages are formed and form, for example, a rotor for a turbo molecular pump. As a result, the individual hub elements can be connected to a rotor shaft or form the rotor shaft themselves by being connected to one another accordingly. With the hub element 10, rotor blades 12 which run radially in the circumferential direction and are set at an angle are connected, with only a single rotor blade 12 being shown for the purpose of illustration.

To illustrate the multilayer structure, the drawing also shows an exploded view of the individual layers. Here, a base element 14 is shown as the middle layer. The construction of the entire vacuum pump rotor in the illustrated preferred embodiment is constructed symmetrically to the base element 14. A stiffening element 16 is arranged on the base element 14, a further stiffening element being arranged symmetrically to the base element 14 on the opposite side, symmetrically to the stiffening element 16 shown. The same also applies to the next layer, which is formed by an inner additional wing element 18, the second additional wing element 18 again being provided on the opposite side symmetrically to the base element 14. Correspondingly, two outer additional wing elements 20 are also provided and again arranged symmetrically to the base element 14. As a further element, two holding elements 22 are provided, which in turn are arranged symmetrically to the base element 14. The holding elements 22 represent the essential elements of the hub element 10.

In the preferred embodiment shown, the base element 14, which forms the plane of symmetry, has an outer contour which corresponds to the outer contour of the wing 12. The base element 14 here has a hub part 24 which protrudes into the hub element 10 or is arranged between the two holding elements 22 of the hub element 10. It must be taken into account here that the two holding elements 22 are in particular ring-shaped are formed, wherein a plurality of hub parts corresponding to the number of rotor blades 12 are arranged between these two annular holding elements 22. A wing foot 26 is connected to the hub part 24 and, in particular, is formed in one piece. The wing foot 26 represents the connecting element between the hub part and a wing head 28. The wing head 28 is the essential component of the rotor blade 12. The base element 14 is preferably formed in one piece and, in a preferred embodiment, has a carbon fiber fleece.

The next layer is formed by the two mutually opposite stiffening elements 16. In the exemplary embodiment shown, the outer contour of the stiffening elements 16 corresponds to the outer contour of the hub part 24 and the wing root 26. If necessary, the stiffening element 16 protrudes only into part of the wing root 26. The stiffening element has a fixing element 30 on an inner side. This protrudes axially outward and engages behind the two holding elements 22. The stiffening element 16 is preferably designed as a tangential layer and in this respect has a large number of fibers that are suitable in the circumferential direction for absorbing tangential forces. The thickness gradient on the inside of the hub is high here.

The next layer of material is formed by the two inner additional wing elements 18. The outer contour of the inner additional wing elements corresponds to the outer contour of the base element. The inner additional wing elements 18 also have a fixing element 32 which engages behind the holding elements 22 radially in accordance with the fixing element 32. The material fibers of the inner additional wing elements 18 are preferably aligned radially so that these layers can be viewed as radial layers.

The next layers of material are formed by the outer additional wing elements 20. The outer contour of the outer additional wing elements 20 in turn corresponds to the outer contour of the base element 14 the outer additional wing elements 20 also have a fixing element 34, which in turn engages behind the two holding elements 22 radially. It is preferred that the outer additional wing elements 20 are made from a spreadtow fabric.

The outer material layer is formed by the two holding elements 22, these not extending into the rotor blade 12, but essentially forming the hub element. The holding elements 22 also preferably have material fibers, in particular plastic fibers or carbon fibers.

The multi-layer structure of the vacuum pump rotor is essential for the invention. The design and the choice of material for the individual layers are preferably selected in such a way that a material selection that is as appropriate to the demands as possible and a fiber orientation that is appropriate to the demands are realized. In this way, vacuum pump rotors can be produced which can withstand extremely high loads and in particular can achieve a tip speed of more than 400 m / s, in particular more than 500 m / s and in particular more than 600 m / s.

Claims (12)

1. A vacuum-pump rotor, in particular for turbomolecular pumps, comprising

   a hub element (10) for connecting to a rotor shaft and/or for forming a rotor shaft, and

   rotor blades (12) connected to the hub element (10),

   wherein the hub element (10) and/or the rotor blades (12) comprise a plurality of material layers,

   wherein a plurality of rotor blades (12) surrounding the hub element (10) are provided, each comprising a blade foot (26) connected to the hub element (10) and a blade head (28) connected thereto,

   wherein the hub element (10) comprises at least one holding element (22), wherein a base element (14) comprising fiber-reinforced material is provided as a material layer, said base element being directly or indirectly connected to the least one holding element (22),

   wherein the base element (14) comprises a hub member (24) arranged in the hub element (10) and forms the foot (26) and also the head (28) of a rotor blade,

   wherein at least one stiffening element (16) preferably comprising a fiber-reinforced material is provided as further material layer/s, said stiffening element being connected to the holding element (22) by face-to-face contact and protruding into the blade foot (26) of the roto blade (12),

   wherein the outer contour of the stiffening element (16) corresponds to the outer contour of the hub member (24) and of the blade foot (26),

   characterized in that

   at least one additional blade element (18, 20) comprising fiber-reinforced material is provided as further material layer/s, said additional blade element being connected to the holding element (22) and protruding into the blade foot (26) and into the blade head (28),

   the stiffening element (16), in the area of the blade foot (26), is in direct abutment on the base element (14) and on the additional blade element (18, 20) by face-to-face contact and is arranged between the base element and the additional blade element, and that

   the holding (22) comprises a fiber-reinforced material.
2. The vacuum-pump rotor according to claim 1, characterized in that at least one of the material layers comprises fiber-reinforced material.
3. The vacuum-pump rotor according to any one of claims 1 to 2, characterized in that the hub element (10) comprises two mutually opposite holding elements (22) having arranged between them a hub member (24) of the base element (14), and/or that the stiffening element (16) comprises, on an inner side, a fixing element (30) extending preferably at least partially axially and/or engaging behind the holding element (22).
4. The vacuum-pump rotor according to any one of claims 1 to 3, characterized in that two mutually opposite stiffening elements (16) are arranged on different sides of the base element (14).
5. The vacuum-pump rotor according to any one of claims 1 to 4, characterized in that the at least one additional blade element (18, 20) comprises, on an inner side, a fixing element (32) extending preferably at least partially axially and/or engaging behind the holding element (22).
6. The vacuum-pump rotor according to any one of claims 1 to 5, characterized in that one of the additional blade elements (18) comprises a radial layer of fiber-reinforced material.
7. The vacuum-pump rotor according to any one of claims 1 to 6, characterized in that one of the additional blade elements (20) comprises a spread tow fabric layer.
8. The vacuum-pump rotor according to claim 6, characterized in that at least one of the additional blade elements is designed as an inner additional blade element (18) preferably connected to a blade head (28) of the base element (14) by face-to-face contact.
9. The vacuum-pump rotor according to claim 7, characterized in that at least one of the additional blade elements is designed as an outer additional blade element (20) preferably connected to the inner additional blade element (18) by face-to-face contact.
10. The vacuum-pump rotor according to any one of claims 1 to 9, characterized in that the base element (14) and at least one additional blade element, preferably all additional blade elements (18, 20), have substantially the same outer contour, preferably a blade-shaped outer contour.
11. The vacuum-pump rotor according to one of claims 9 and 10, characterized in that, in the area of the blade foot (26) and/or the blade head (28), the inner additional blade element (18) is in direct abutment on the outer additional blade element (20) by face-to-face contact.
12. The vacuum-pump rotor according to any one of claims 1 to 11, characterized in that the rotor relative to the base element (14) is of a symmetrical multilayered design.

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