Rotor and Vacuum Pump

Abstract

A rotor for vacuum pumps and preferably turbomolecular pumps, comprising a support member connectable to a rotor shaft having a plurality of rotor blades, each of the plurality of rotor blades comprising a plurality of layers perpendicular to the axial direction of the rotor, each of the plurality of layers being at least partially formed as an arcuate curve connected at a respective end to the support member, the plurality of layers being arranged laterally offset with respect to each other.

Description

[Technical field]

[0001] The present invention relates to a rotor, preferably for a turbomolecular pump, and to a vacuum pump equipped with such a rotor. [Background technology]

[0002] The known vacuum pump comprises a housing having an inlet and an outlet. A rotor assembly is arranged in the housing, which is rotated by an external power source, such as an electric motor. At least one rotor element is attached to a rotor shaft, and the rotation of the rotor assembly transports a gaseous medium from the inlet to the outlet. In that respect, the rotor element may be made of one or more rotor disks, in particular for turbomolecular pumps. In that respect, the rotor disks are provided with a number of inclined surfaces, usually made as blades, to provide a pumping action. The known pump comprises a number of pump stages, each pump stage for turbomolecular pumps being composed of at least one rotor disk interacting with at least one stator element coupled to the housing.

[0003] Due to the high speed rotation of the rotor assembly, high structural requirements are imposed on the rotor blade components, in that the centrifugal forces acting on the rotor blades usually limit the rotational speed of the vacuum pump, thereby simultaneously limiting the maximum performance of the vacuum pump, therefore there is a need for rotor blades with high structural stability.

[0004] However, increasing the structural stability of the rotor also increases the weight of the rotor assembly, which leads to higher bearing requirements and increases the cost of the vacuum pump, and it also increases the stored energy in the rotor, limiting pump performance and potentially raising safety concerns.

[0005] It is well known that composite materials, especially carbon fiber reinforced plastics (CFRP), have the potential to significantly improve the above limitations. CFRP is widely used in the Holweck skits of TMPs, but not in the turbo blade section of the rotor. The reason is the complex design and the associated high manufacturing costs. The connection point between the radially oriented blades and the circumferentially oriented hub has been found to be a weak point. Mitigating this weak point would increase the cost and weight of the rotor disk. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to provide a rotor assembly that is easy to manufacture, lightweight and cost effective. [Means for solving the problem]

[0007] This object is solved by a rotor according to claim 1 and by a vacuum pump according to claim 19.

[0008] In one aspect of the invention, a rotor, preferably for a turbomolecular pump, is provided. The rotor assembly is often composed of one or more rotor disks. The rotor disks, also known by the term blade disks or "blisks", form the rotor elements of one pump stage of a vacuum pump. The rotor disks of the rotor can be made separately and assembled to the rotor shaft. Alternatively, two or more rotor disks can be made integrally, preferably monolithically. The rotor disk comprises a support member that can be coupled to the rotor shaft. In that respect, the support member usually comprises a circular or approximately circular opening that is coupled to the rotor shaft of the vacuum pump. However, openings of other shapes are also possible. In general, the openings of the support member have a shape that is adapted to the shape of the rotor shaft in order to transmit the rotation of the rotor shaft to the support member and, consequently, to the rotor disk. Furthermore, the rotor disk comprises a plurality of rotor blades. In that respect, each of the plurality of rotor blades comprises a plurality of layers perpendicular to the axial direction of the rotor disk.

[0009] Here and below, the axial direction is defined by the axial direction of the rotor shaft, i.e. coincident with the axis of rotation of the rotor, and the transverse direction is the direction in a plane perpendicular to the axial direction.

[0010] The layers are arranged in an assembled state along the rotor shaft, where each of the layers for one of the rotor blades is at least partially formed as an arcuate curvature, and each arcuate curvature is connected at its end to the support member. The layers for one rotor blade are laterally or angularly offset relative to each other. In other words, the arcuate curvatures of one layer relative to the arcuate curvatures of another layer of each blade are circumferentially offset relative to each other. Thus, the succession of layers and the lateral or angular offset between each layer creates an angled surface that provides a pumping action during rotation of the rotor disk. In particular, the arcuate curvatures of the layers for one rotor blade are axially connected to each other to create a closed surface or sidewall, the shape of which follows the contour and internal line of the arcuate curvatures of the individual layers and is inclined with respective to the axial direction of the rotor disk. Therefore, the present invention modifies the conventional blade shape of the rotor disk, thereby avoiding the problems of the prior art for connecting such conventional rectangular rotor blades to the support members, and thus provides an alternative design that provides high structural stability that can be easily implemented with carbon fiber reinforced plastic or other materials.

[0011] In another aspect of the invention, a rotor, preferably for a turbomolecular pump, is provided. In many cases, the rotor assembly is composed of one or more rotor disks. The rotor disks of the rotor can be made separately and assembled to the rotor shaft. Alternatively, two or more rotor disks can be made integrally, preferably monolithically. The rotor disks form the rotor element of one pump stage of the vacuum pump. The rotor disks comprise a support member which can be coupled to the rotor shaft. In that respect, the support member usually comprises a circular or approximately circular opening which is coupled to the rotor shaft of the vacuum pump. However, openings of other shapes are also possible. In general, the openings of the support member have a shape adapted to the shape of the rotor shaft in order to transmit the rotation of the rotor shaft to the support member and, consequently, to the respective rotor disk. Furthermore, the rotor disk comprises a plurality of rotor blades.

[0012] In that respect, each of the rotor blades forms at least a partial arcuate curvature in a cross section in a plane perpendicular to the axial direction, the arcuate curvature being connected at each end to a support member. The arcuate curvatures of a first cross section and a second cross section at different axial positions of the same blade are angularly offset relative to each other. A plurality of cross sections arranged along the axial direction can be defined. The arcuate cross sections for one rotor blade are laterally or angularly offset relative to each other. In other words, the arcuate curvatures of one cross section relative to the arcuate curvatures of another cross section are circumferentially offset relative to each other. Thus, the series of arcuate cross sections and the lateral or angular offset between each of the cross sections create an angled surface that provides a pumping action during rotation of the rotor disk.

[0013] In particular, a third cross section can be defined, with the first, second and third cross sections being arranged in consecutive order along the axial direction, and the angular or lateral offset between the arcuate curves of the first and second cross sections being in the same direction as the angular or lateral offset between the arcuate curves of the second and third cross sections, so as to form a continuous shape of the blade.

[0014] In particular, the cross-sectional arcuate sections of one rotor blade are connected to each other in the axial direction to form a closed surface or side wall, the shape of which follows the outer contour and inner line of the individual cross-sectional arcuate sections and is inclined with respect to the axial direction of the rotor disk. Thus, the present invention modifies the conventional blade shape of the rotor disk, thereby avoiding the problems of the prior art for connecting such conventional rotor blades to a support member. Thus, an alternative design is implemented that provides high structural stability that can be easily implemented with carbon fiber reinforced plastic or other materials.

[0015] Preferably, for the present invention, materials that have anisotropy, such as better mechanical properties in one or two spatial directions, are desired.

[0016] Preferably, the bow is configured to only exhibit tensile forces parallel to the bow, thus ensuring optimal force transfer since forces are only applied along the direction of maximum possible distortion of the material, thereby improving the structural stability of the individual blades and rotor disk.

[0017] Preferably, the individual layers / sections of the rotor blades are arranged in a common plane or staggered in subsequent planes, so that for example the first layer / section of one rotor blade is arranged in the same plane as the first layer / section of another rotor blade, or in another example, the first layer / section of one rotor blade is arranged in a plane directly preceding the plane in which the sections of another rotor blade are arranged, allowing for a layered structure that simplifies the manufacturing process.

[0018] Preferably, the rotor disk is manufactured by an additive manufacturing method such as fused filament manufacturing.

[0019] Preferably, at least one of the rotor blades has a wall thickness or density that varies along the arc. Thus, the wall thickness can vary along the length of the arc from a first end of the respective arc, which is connected to the support member, to a second end of the arc. Preferably, the variation is symmetric between the first end of the arc and the tip of the arc, which is the tip of the rotor blade. However, it is also possible that the thickness varies multiple times along each rotor blade.

[0020] Preferably, the thickness of the rotor blade is varied to change the shape of the bow while maintaining only the tension in the bow.

[0021] Preferably, the rotor blade thickness varies such that the thickness is thickest at the leading and / or trailing edge of each rotor blade and thinnest at the tip of the blade.

[0022] Preferably, the wall thickness of one rotor blade is different from the wall thickness of another rotor blade. Thus, each rotor blade can be of similar construction in terms of its wall thickness, or different blades can have different wall thicknesses. Thus, the wall thickness can be freely selected to improve the pump performance and reduce the weight of the rotor disk, while maintaining the structural stability of the rotor disk.

[0023] Preferably, each of the plurality of rotor blades includes the same number of layers. Alternatively, at least two of the plurality of rotor blades include a different number of layers. In that regard, the individual rotor blades can be made in different ways with different structural shapes to meet specific needs with respect to pump performance and structural stability.

[0024] Preferably, the lateral or angular offset of the multiple layers / sections is constant for each of the layers / sections. Alternatively, the lateral or angular offset between the multiple layers / sections can be different and vary from one layer / section to another. Thus, by varying the lateral or angular offset between the layers / sections, the shape of the individual blades in the axial direction can be tailored to specific needs regarding pump performance and structural stability.

[0025] Preferably, the lateral or angular offset is the same for each of the rotor blades. Alternatively, at least two rotor blades implement different lateral or angular offsets from one of their layers / sections to another, in particular with respect to corresponding layers / sections. Thus, the individual rotor blades can be made similar or different with respect to their lateral offset, i.e. axial shape. The lateral offset determines the inclination of each blade. Increasing the offset reduces the inclination. By implementing different lateral offsets for different blades, different inclinations can be adapted to each application to improve pump performance. The inclination can be defined as the angle between the blade surface and a plane perpendicular to the axis of rotation.

[0026] Preferably, the wall inclination of each of the plurality of rotor blades, i.e. the angle between the wall and a plane perpendicular to the axis of rotation, decreases as the distance from the support member to the tip of the rotor blade increases, so that fast rotating portions of the tips of individual rotor blades can have different wall inclinations which increases the pumping performance of the rotor disk.

[0027] Preferably, each of the bows comprises a first end and a second end coupled to the support member, the first end and the second end being spaced apart from one another, such that the bow does not end where it begins at the support member, thereby creating a sling defined by bows of separate layers.

[0028] Preferably, the first and second ends of the arcuate portions of one blade, preferably two or more blades, more preferably all of the blades are coupled to the support member at opposing locations along the circumference of the support member, thus allowing optimal force transfer of rotational forces from the individual blades to the support member while at the same time providing a more stable tangential coupling of the individual blades to the support member.

[0029] Preferably, each arcuate curvature of one layer / section preferably has a first end and a second end connected to the support member, and the arcuate curvatures of all the blades of the respective layer / section combine to form a continuous line. Thus, the arcuate curvature in the common layer / section of all the blades is a continuous shape that can be called hypotrochoid or is very similar in appearance. In that respect, the arcuate shape can be formed by continuous fibers of, for example, fiber-reinforced plastic. In other words, the second end of the first blade coincides with the first end of another blade, and so on until the second end of the last blade coincides with the first end of the first blade. In that respect, preferably, at the position where the first end of one blade and the second end of another blade coincide, the transition is kink-free, i.e. has the same slope / curvature. In other words, the first derivative at the first end of one blade is equal or nearly equal to the derivative at the second end of the other blade. In that respect, in particular, each arcuate portion can extend along the outer surface of the support member to increase the contact surface between the blade and the support member. In other words, the first end of one blade can be connected to the second end of the other blade by a middle section, respectively, and the middle section portion can form the support member. The middle section can extend along the shape of the support member, and the combination of all the middle sections or all the layers / sections can form the support member. This combination of arcuate portions exhibits increased durability and strength, while being simple to manufacture.

[0030] Preferably, the number of tips / slings / blades

number

number

number

[0031] Preferably, each of the arcuate curves comprises a first end and a second end connected to the support member, the first end and the second end of one blade being directly connected by the respective first end and second end of the opposing blade. Thus, the arcuate curves of two opposing blades can be directly connected and their shape can be created by combining them by a continuous sling. Alternatively, the arcuate curves of two opposing blades can be connected by a middle section, which can form the support member. In other words, the second end of the first blade is connected to the first end of the opposing second blade by the middle section, and the second end of the second blade is connected to the first end of the first blade by the middle section. The middle section can extend along the shape of the support member, and the combination of all the middle sections or the combination of all the layers / sections can form the support member.

[0032] Preferably, each of the arcuate curves includes a first end and a second end coupled to the support member, the first end and the second end being at the same axial location. Thus, the arcuate curves terminate at the same axial location or height starting from the support member. In particular, the individual layers of each arcuate curve are perpendicular to the axis of rotation.

[0033] Preferably, each of the arcuate curves comprises a first end and a second end connected to the support member, the first end and the second end being at different axial positions. Thus, the arcuate curves do not end at the same axial position or axial height starting from the support member. This creates a sling defined by the arcuate curves of the individual layers. In particular, the individual layers of each arcuate curve are inclined about an axis perpendicular to the axial direction. Thus, the resulting blade shape can be adapted to specific needs, thereby optimizing the performance of the rotor.

[0034] Preferably, the stiffening element of each blade follows the arcuate curvature, in particular the projection of the stiffening element of each blade onto a plane perpendicular to the axial / rotational axis follows the arcuate curvature.

[0035] Preferably, for a rotor blade, at least one layer / section, preferably two or more, most preferably all layers / sections have a parabolic or nearly parabolic shape. In that respect, the shape of the arcuate curve is defined by a parabolic function to ensure that the tensile forces are parallel to the arcuate curve. In particular, when the first and second ends of each arcuate curve are at different axial positions, the axial projection of the arcuate curve has a parabolic or nearly parabolic shape. In that respect, the axial projection is defined as the projection along the axial direction of the rotor shaft.

[0036] Preferably, for one rotor blade, at least one layer / section, preferably two or more, most preferably all layers / sections have a catenary shape or a near catenary shape. In that respect, the shape of the bow is defined by a catenary function to ensure that the tensile forces are parallel to the bow. In that respect, the catenary function is usually proportional to a cosh function. In particular, when the first and second ends of each bow are at different axial positions, the axial projection of the bow has a catenary shape or a near catenary shape. In that respect, the axial projection is defined as the projection along the axial direction of the rotor shaft.

[0037] Preferably, for a rotor blade, at least one layer / section, preferably two or more, most preferably all layers / sections have a troposkein shape or a troposkein shape. In that respect, the shape of the arcuate curve is defined by a troposkein function to ensure that the tensile forces are parallel to the arcuate curve. In that respect, the troposkein function is usually proportional to a Jacobian elliptic sine function (denoted by "sn" and also called sinus amplitudinis). In particular, when the first and second ends of each arcuate curve are at different axial positions, the axial projection of the arcuate curve has a troposkein shape or a troposkein shape. In that respect, the axial projection is defined as the projection along the axial direction of the rotor shaft.

[0038] Preferably, for one rotor blade, at least one layer / section, preferably two or more, most preferably all layers / sections have a hypotrochoidal or near hypotrochoidal shape. In that respect, the shape of the arcuate curve is defined by a hypotrochoid to ensure that the tensile forces are parallel to the arcuate curve. In particular, when the first and second ends of each arcuate curve are at different axial positions, the axial projection of the arcuate curve has a hypotrochoidal or near hypotrochoidal shape. In that respect, the axial projection is defined as the projection along the axial direction of the rotor shaft.

[0039] Preferably, for a rotor blade, at least one layer / section, preferably two or more, and most preferably all layers / sections have a symmetrical shape that is mirrored along a line perpendicular to the axial direction, connecting the axis of rotation and the point of the shape furthest from the axis of rotation. The lengths of the shapes on either side of the axis of reflection may, but need not, be equal.

[0040] Preferably, each blade is at least partially made from a fibre reinforced plastic (FRP), such as a carbon fibre or fibre glass FRP, in particular the rotor, i.e. the rotor disk, is made entirely from FRP.

[0041] Preferably, the rotor or rotor disk is monolithic.

[0042] Preferably, the bow is made of a sling or filament. More preferably, continuous filament can be used. Alternatively, a closed sling material can be used to increase the structural stability of the individual blades.

[0043] Preferably, the fibers are positioned along each arcuate curve to ensure optimal force transmission from the tip of each blade to the support member.

[0044] Preferably, the projections of the fibers onto each cross section are disposed along an arcuate curve.

[0045] Preferably, each of the multiple layers is at least partially made from a metal band. The metal band or bands improve stability in one or two directions (perpendicular to the width of the band). In addition, metal bands have a high ability to withstand tensile forces applied along the length of the band material. Thus, each layer can be created by the band material bonding the individual layers together to create an individual blade shape.

[0046] Preferably, the arcuate curvatures of the rotor blades overlap or are spaced apart from one another in a plane perpendicular to the axial direction or on the surface of a mathematical cone having circular symmetry, whereby the axis of rotation of the rotor coincides with the line of symmetry of the cone. Thus, the arcuate curvature of one rotor blade may be spaced apart from the arcuate curvature of another adjacent rotor blade. Alternatively, adjacent rotor blades may overlap.

[0047] Preferably, the length of the arc may vary from one layer / section to another within a rotor blade, so that the radial extension of an individual blade can be tailored to specific needs.

[0048] Alternatively, the length of the bow may be constant for all layers / sections of a blade.

[0049] Preferably, the shape of the arcuate curve can vary from one layer / section to another of one particular rotor blade, thereby allowing the shape of the individual rotor blades to be tailored in the axial direction.

[0050] Preferably, all the blades of one rotor disk have the same shape, or at least two of the rotor blades are made to have different shapes.

[0051] According to another object of the present invention, there is provided a vacuum pump comprising at least one rotor disk as described above, in that the rotor disk is coupled to a rotor shaft of the vacuum pump and is preferably rotated by an electric motor, whereby the rotor disk interacts with a stator element coupled to a housing of the vacuum pump to provide pumping action and transport gas from an inlet to an outlet of the vacuum pump.

[0052] Preferably, the vacuum pump comprises a plurality of rotor disks as described above, in particular rotor disks each interacting with a respective stator, in which respect the rotor disks can be made identical or the shape of the rotor disks can vary.

[0053] In the following, the invention is explained in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0054] [Figure 1] 1 illustrates a vacuum pump according to an embodiment of the present invention. [Figure 2A] 2 illustrates details of a rotor disk according to the present invention; [Figure 2B] 2 illustrates details of a rotor disk according to the present invention; [Figure 2C] 2 illustrates details of a rotor disk according to the present invention; [Figure 3A] 3 is an embodiment of a detailed view of a cross section, layer or layer projection of a rotor disk according to the present invention; [Figure 3B] 3 is an embodiment of a detailed view of a cross section, layer or layer projection of a rotor disk according to the present invention; [Figure 4A] FIG. 1 is a diagram of one embodiment of the present invention. [Figure 4B] FIG. 1 is a diagram of one embodiment of the present invention. [Figure 5A] FIG. 2 is a diagram of another embodiment of the present invention. [Figure 5B] FIG. 2 is a diagram of another embodiment of the present invention. [Figure 6A] FIG. 2 is a diagram of another embodiment of the present invention. [Figure 6B] FIG. 2 is a diagram of another embodiment of the present invention. [Figure 7] FIG. 2 is a flow diagram of a manufacturing method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] With reference to FIG. 1, a vacuum pump made as a turbomolecular pump is shown. The vacuum pump comprises a housing 10 including an inlet 12 and an outlet 14. A rotor shaft 16 is arranged in the housing and is supported by a first radial bearing 18, made as a permanent magnet bearing in the example of FIG. 1, and a mechanical ball bearing 31. The first radial bearing 18 comprises a number of magnet rings 22, 23. At that point, a stationary magnet ring 26 of the radial bearing 18 is mounted on a trunnion 24 that extends into a recess in the rotor shaft 16. The rotating magnet ring 22 is arranged radially adjacent to the stationary magnet ring 26 on the inner surface of the recess.

[0056] Furthermore, the radial bearing 18 comprises an emergency running bearing 30 (upper side) made as a ball bearing. The rotor shaft 16 is driven by an electric motor 32. On the rotor shaft 16 are mounted a number of pump elements made as rotor disks 34, which are coupled to the housing 10 of the vacuum pump and interact with stator elements 36 arranged alternately with the rotor disks 34. In addition, the vacuum pump of Fig. 1 comprises a Holweck stage 38, which includes a rotating cylinder 40 interacting with a threaded stator 42 coupled to the housing. Due to the rotation of the rotor shaft 16, the gaseous medium is transported from the inlet 12 towards the outlet 14 of the vacuum pump.

[0057] 2A-2C. In accordance with the present invention, the rotor disk 34 comprises a support member 100 having an angular or near-angular opening 101. The support member 100 can be attached to the rotor shaft 16 of a rotor assembly to couple the rotor disk 34 or blade disk to the rotor shaft 16. Referring to FIG. 2B, a detailed view of the rotor disk 34 is shown. The support member 100 in the first layer has an arcuate portion 102 attached thereto, with a first end 102A and a second end 102B of the arcuate portion 102 being attached to the support member 100 spaced apart from each other. The arcuate portion has a defined width W, which defines a thickness of the sidewall and creates and surrounds the opening 103. Additionally, the arcuate portion has a defined height in the axial direction. The arcuate portion 102 in the first layer thereby creates a portion of the sidewall or sloping wall that provides the pumping effect of the rotor disk. As shown in FIG. 2C, the arcuate curve 102 of the first layer is repeated in the subsequent second layer to provide a second arcuate curve 104 that is axially displaced and laterally or angularly offset relative to the arcuate curve 102 of the first layer. Additionally, FIG. 2C shows a third arcuate curve 106 in the third layer. In that regard, in FIG. 2B and FIG. 2C, only one rotor blade is shown for simplicity and illustrative purposes. However, the bladed disk can include multiple rotor blades. The arcuate curves 102, 104, 106 of the different layers are coupled together to create a sidewall or solid surface that provides a pumping effect when the rotor disk rotates in the vacuum pump. In that regard, the sidewall can be made stepped to provide a stepped sloping wall. Alternatively, the sidewall can be continuous to provide a smooth surface. In that regard, each rotor blade includes multiple layers. In Figure 2C, three layers are illustrated for simplicity and illustrative purposes, however, the number of layers can be more than 20, preferably more than 50, and more preferably more than 100. Subsequent layers provide continuous coupling of each arc, specifically, there is no space between each subsequent layer and each arc to form a closed surface for pumping.

[0058] In other words, in particular if the rotor is not made in layers, the cross-sections in the plane perpendicular to the axial direction are considered as layers. In this respect, the axial direction corresponds to the axial direction and rotation axis of the rotor shaft. As mentioned above and with respect to layers, in each cross-section, the blades are made by arcuate curvatures, such as the arcuate curvatures 102, 104, 106 as shown in Figures 2A to 2C. As a result, in the following, layers can be replaced by cross-sections.

[0059] In particular, if the rotor is made from long fiber, thin strip or continuous fiber reinforcement, the projection of this reinforcement onto a plane perpendicular to the axis of rotation follows the shape of the bow as described by this invention.

[0060] Although FIGS. 2B and 2C show the sidewall thickness created by the arcuate curves 102, 104, 106 to be constant, i.e., W shown in FIG. 2B is constant along the entire arcuate curve, in other embodiments, the sidewall thickness created by the arcuate curves 102, 104, 106 can vary along the individual arcuate curves 102, 104, 106 or can vary from one layer to another to provide an axially increasing or decreasing wall thickness.

[0061] 2C further illustrates that the length and shape of the arcuate curves 102, 104, 106 are the same. However, in other embodiments, either the length or the shape of the arcuate curves 102, 104, 106, or both, can vary from one layer to another in order to axially match the shape of the blade 105.

[0062] The shape of the bows 102, 104, 106 can be given by a parabolic function. Alternatively, the bows can have a shape given by a catenary curve, including a cosh function, or can be given by a troposkein or a very similar shape. The given choice of the shape of the bows 102, 104, 106 allows all tensile forces introduced into a particular blade 105 by the rotation of the rotor disk to be parallel to the bow and thus parallel to the direction of the highest possible tensile force of the material. Thus, if the bow is made, for example, by fiber-reinforced plastic, fibers, in particular long or continuous fibers, or closed fiber loops, extend along the bow and provide structural stability in the direction of the tensile forces, thereby improving the structural stability of the rotor blade. As a result, higher rotational speeds can be applied to a particular rotor blade, improving the pump performance. Thus, by deviating from the conventional blade design in which rectangular blades are bonded to an annular support structure, a stable and easy-to-manufacture rotor disk can be achieved. As the rotor disk rotates, as illustrated by arrow 107 in FIG. 2C, the inclined surface 109 provides a pumping action on particles of the gaseous medium towards the outlet of the vacuum pump.

[0063] Figure 3A shows a first embodiment in which the rotor blades 108, 108' are illustrated with arcuate curvatures. In particular, the rotor disk of Figure 3A can have more than six rotor blades, more than ten rotor blades, etc. However, in the embodiment of Figure 3A, the arcuate curvatures of the individual rotor blades 108, 108' do not intersect with each other and are spaced apart and connected to the support member 100.

[0064] Another embodiment, shown in FIG. 3B, illustrates five blades 110 evenly spaced around the circumference of the support member 100, with the arcs of the rotor blades 110 in this embodiment intersecting each other.

[0065] Although Figures 3A and 3B show that the individual rotor blades 108, 108', 110 can have the same size and shape, of course different rotor blades can have different sizes and shapes to provide optimized pumping action via the individual inclined surfaces of the rotor disk.

[0066] With reference to Figures 4A and 4B, another embodiment of the complete rotor disk 34 is shown, which has eleven blades 112 in two projections. In that respect, the thickness of the side walls is selected to be constant, 0.1-5 mm, preferably 0.5-2 mm. Furthermore, the blades create a number of openings 144 with inclined surfaces 116 that provide a pumping action for the particles of the gaseous medium. In that respect, the inclined surfaces 116 have an inclination of 10° to 65°, preferably 10° to 20°, relative to the axial direction, in the example of Figures 4A and 4B. Furthermore, as shown in Figure 4A, the outer rim 113 of the rotor disk 34 is approximately circular, which prevents backflow of the gaseous medium in the vacuum pump between the individual pump stages. However, in the case of a small number of blades, a filling element can be provided between the blades to ensure a circular or at least approximately circular correction of the rotor disk 34, so that the outer rim is close to the housing of the vacuum pump in the assembled state.

[0067] 5A and 5B, a rotor disk according to the present invention is shown having only six blades 114 that provide inclined surfaces within the plurality of openings 154, the inclined surfaces having an inclination of between 10° and 65°, preferably between 15° and 30°, relative to the axial direction to provide optimal pumping efficiency. In that respect, the arc of one blade seamlessly joins the arc of the opposing blade in a layer or cross section. Thus, the stiffening element used to form the blades 114 can be provided as a sling that simultaneously provides two opposing blades.

[0068] Preferably, the axial width of the rotor disc is between 1 mm and 35 mm, preferably between 5 mm and 15 mm. The outer diameter of the rotor disc is preferably between 50 mm and 400 mm, more preferably between 70 mm and 300 mm.

[0069] As shown in Figures 4A, 4B, 5A and 5B, the rotor disk can be made from carbon fiber reinforced plastic (CFRP), preferably containing long fibers, more preferably continuous fibers, to create the arcuate curvature of the individual layers. In that regard, a closed sling can also be used in the example of Figures 5A and 5B to create the opposing rotor blades at once.

[0070] Preferably, additive manufacturing methods, in particular fiber-reinforced fused filament manufacturing methods, can be used to manufacture each rotor blade. In that respect, the arcuate curvatures of each blade of a first layer are arranged in a common plane and are manufactured in a first step. The arcuate curvatures of all blades of subsequent layers are then manufactured, as a result of which each rotor disk can be manufactured layer by layer. In particular, to further increase the structural stability of the rotor disk when using continuous carbon fibers, or closed slings of carbon fibers, these carbon fibers can be interwoven in particular at the intersections of the individual blades.

[0071] Preferably, a filament winding process can be used to manufacture each rotor blade. In that regard, a one or multiple piece mandrel is used to wind the material into the desired shape. Unlike commonly used filament winding processes, this mandrel may not be perfectly convex in the winding direction. The manufacture of such rotor blades requiring a concave mandrel may require more than two axes of motion between the filament source and the mandrel.

[0072] Referring to the embodiment of Figures 6A and 6B, a rotor disk according to the present invention is shown having nine blades 114 that provide inclined surfaces within a plurality of openings 154, the inclined surfaces having an inclination between 10° and 65°, preferably between 15° and 30°, relative to the axial direction to provide optimal pumping efficiency. In Figure 6A, the combined arcuate curves of one common layer or cross section are shown. As shown, the arcuate curves are connected to a single line. The end of one blade becomes the start of another blade and the end of the last blade becomes the start of the first blade. In that respect, the curves can be characterized as following a shape that resembles or substantially resembles a hypotrochoid. The stiffening element can be provided as a continuous sling that makes all the blades together. This improves the load balance within the rotor and increases the durability and strength of the rotor. Figure 6B is a perspective view of the rotor of Figure 6A.

[0073] Referring to Figure 7, there is shown a flow diagram of a method for manufacturing a blade disk according to the present invention. The method includes: S01: providing a support member for coupling a rotor disk to a rotor shaft; S02: Providing an arcuate portion on each of the rotor blades of the rotor disk; S03: repeating the arc of a first layer in a subsequent layer with an angular offset relative to a preceding layer; S04: Repeating step S03 multiple times according to arrow 600 to create the rotor disk layer by layer to obtain the final rotor disk 602; Includes.

[0074] As noted above, the arcuate shapes of the individual blades provided in step S02 need not be identical, and the arcuate shapes repeated in different layers provided in step S03 need not be identical, and the length, sidewall thickness, or shape of each arcuate curve can be adapted to improve rotor disk stability, pump performance, or both.

[0075] Thus, by deviating from the conventional shape of the rotor disk, and in particular its blades, the structural stability can be improved, so that higher rotational speeds can be applied without damaging the rotor. Alternatively, this concept can be used to manufacture rotor blades with a smaller mass and / or lower second moment of inertia, which allows higher rotational speeds. Alternatively, this concept can be used to utilize materials that could not be used for impellers due to their mechanical strength in at least one spatial direction. In particular, the arc is configured such that tension forces in the direction of the highest strength of the material are always or at least substantially parallel along the arc, thus improving the connection points between the individual blades and the support members.

Claims

1. A rotor, preferably a rotor for a turbomolecular pump, comprising: a support member coupleable to a rotor shaft having an axial direction; A plurality of rotor blades; Equipped with each of the rotor blades defines at least a partial arcuate section in cross section taken along a plane perpendicular to the axial direction, the arcuate section being coupled at a respective end to a support member; A rotor, wherein the arcuate portions of the first and second cross sections of each blade are angularly offset relative to one another.

2. A rotor, preferably a rotor for a turbomolecular pump, comprising: a support member connectable to the rotor shaft; A plurality of rotor blades; Equipped with each of the plurality of rotor blades includes a plurality of layers; each of the plurality of layers is at least partially formed as an arcuate curve, the arcuate curve being coupled at each end to the support member; The rotor, wherein the layers of blades are angularly offset relative to one another.

3. 3. The rotor of claim 1, wherein at least one of the rotor blades has a wall thickness that varies along the arc and / or is different for at least two layers of the same rotor blade and / or is different for at least two cross sections of the same rotor blade.

4. 4. The rotor of claim 1, wherein each of the plurality of rotor blades has a constant wall thickness or at least two of the plurality of rotor blades have different wall thicknesses.

5. A rotor according to claim 1 , wherein the angular offset of the layers is constant or the angular offset of the layers is different.

6. The rotor of claim 1 , wherein the slope of the wall of each of the plurality of rotor blades decreases as the distance from the support member to the respective tip of the rotor blade increases.

7. 7. The rotor of claim 1, wherein each of the arcuate curves includes a first end and a second end coupled to the support member, the first end and the second end being spaced apart from one another.

8. 8. A rotor as claimed in any one of claims 1 to 7, wherein each of the arcuate curves has a first end and a second end, the arcuate curves of all the blades combining to form a continuous line, the first end of one blade being joined to the second end of another blade, preferably by an intermediate section, the intermediate section being capable of forming the support member.

9. 8. A rotor as claimed in any one of claims 1 to 7, wherein each of the arcuate curves has a first end and a second end, the arcuate curves of opposing blades combining to form a continuous line, the first end of one blade being joined to the second end of another blade, preferably by an intermediate section, the intermediate section being capable of forming the support member.

10. A rotor as claimed in any preceding claim, wherein the arcuate portion has a substantially parabolic shape.

11. A rotor as claimed in any preceding claim, wherein the arcuate portion has a substantially catenary shape.

12. A rotor as claimed in any preceding claim, wherein the arcuate curve has a substantially troposkein shape.

13. A rotor as claimed in any preceding claim, wherein the arcuate curve has a substantially hypotrochoidal shape.

14. A rotor according to any one of the preceding claims, wherein each of said layers is at least partially made from a fibre reinforced plastic (FRP) material, in particular from a carbon fibre reinforcement or glass fibre reinforcement.

15. The rotor of claim 14 , wherein the FRP material comprises a continuous fiber or closed sling material.

16. A rotor as claimed in any one of claims 1 to 15, wherein each of the plurality of layers is made at least in part from a band of metal.

17. 17. The rotor of claim 1, wherein the arcuate portions of the rotor blades overlap or are spaced apart from one another in a plane perpendicular to the axial direction.

18. 18. The rotor of claim 1, wherein one or more of a length and a shape of the arcuate portion of each of the layers of a rotor blade vary.

19. A vacuum pump comprising a rotor or at least one rotor disk according to any one of claims 1 to 18.

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