Wave arrangement

Abstract

Wave arrangement comprising: a hollow shaft (3) with a rotation axis (B), wherein the hollow shaft is designed as a motor shaft for an electric motor and has a shaft tube (11) and two pin elements (13, 13') connected to it at the ends (12, 12'), a hub body (4) which is positively connected to the hollow shaft (3) and has a rotor lamination stack made up of several rotor laminations, wherein the hollow shaft (3) in cross-section has a circumferentially closed wall (5) with several support sections (6) distributed around the circumference, which are in contact with the hub body (4), and spring sections (7) which are spaced apart from an inner circumferential surface of the hub body (4), wherein inner surface areas of the spring sections (7) lie on a smaller radius around the axis of rotation (B) than inner surface areas of the support sections (6).

Description

[0001] The invention relates to a connection arrangement with a shaft and a hub for an electric motor of a motor vehicle.

[0002] From DE 196 24 048 A1, a method for producing a friction-fit connection between a shaft and a hub is known. To avoid surface damage during assembly, one of the components is plastically deformed into an oval or polygonal shape by applying a force. Then, by applying a further force, the oval or polygonal component is largely elastically rounded. The components are assembled while maintaining the further force, and subsequently, the further force is released, causing the rounded component to spring back into an oval or polygonal shape, thus connecting the components by means of an interference fit. The hub is designed in the form of a bushing.

[0003] From DE 10 2016 202 416 A1, a rotor shaft arrangement for a rotor of an electric motor is known. The arrangement comprises a cylindrical hollow shaft for receiving a rotor body and a cooling element arranged in the hollow shaft.

[0004] A shaft-hub connection is known from DE 10 2010 047 445 A1. The shaft has a corrugated profile as its outer contour in the area where it is inserted into the hub. The opening of the hub has a hollow profile as its inner contour in the area where the shaft is inserted. In an assembled position, the outer contour of the shaft and the inner contour of the hub have a gap between them over their entire circumference. In a functional position, where the shaft and the hub are rotated relative to each other by an angle, the shaft and the hub are in contact with each other in at least two contact areas.

[0005] From DE 102 24 477 A1, a detachable shaft-hub connection is known which comprises several tolerance compensation devices between the shaft and the hub. The tolerance compensation device comprises several webs evenly distributed around the circumference of the shaft or the hub and firmly connected to it, each of which has a spring arm bearing against the hub or the shaft under preload.

[0006] From DE 10 2010 039 008 A1, a rotor and a manufacturing process for it are known. The rotor has a rotor shaft and a laminated core arranged along a longitudinal section around the rotor shaft. Along the longitudinal section, the rotor shaft has a first surface area whose shape describes a circular cylinder, and a second surface area formed by structural elements that rise radially outwards with respect to the rotor axis above the first surface area.

[0007] From DE 195 21 755 C1, a connection system for the detachable joining of two components is known. For this purpose, one component is temporarily deformed during the joining process such that an effective circumferential contour corresponds to the corresponding circumferential contour of the other component with a predetermined clearance. After positioning both components, a fixed pressure connection of the two effective circumferential contours is created by at least partial re-deformation.

[0008] From WO 99 / 65 643 A1, a method for producing a detachable connection between a hollow body and a shaft is known. In this method, a hollow body is elastically deformed by radial compressive forces such that an effective circumferential contour corresponds to the corresponding effective circumferential contour of the shaft with a predetermined clearance, allowing the two components to be inserted into one another. After the two components are inserted, a compression connection is created by elastically deforming the hollow body back to its original shape by reducing the radial compressive forces.

[0009] From DE 10 2015 012 912 A1, a rotor for an electric machine is known. The rotor comprises a rotor shaft and several laminated lamination stacks positively attached to it. The rotor shaft has several positive locking elements and, in the area of ​​the laminated lamination stacks, has a non-circular cross-section to form these elements.

[0010] From DE 10 2016 215 760 A1, a rotor for an electric motor of a vehicle is known. The rotor has a central shaft and a laminated core arranged between two retaining discs.

[0011] It is known to attach a hub body to a shaft using an interference fit, allowing torque to be transmitted between these parts. Depending on the technical requirements, the respective diameters of the shaft and hub must be manufactured with high precision. At high rotational speeds of the shaft-hub connection, the interference fit forces may decrease.

[0012] The object of the present invention is to propose a connection arrangement with a shaft and a hub for an electric machine which ensures reliable torque transmission even at high speeds and which is easy and inexpensive to manufacture.

[0013] A shaft arrangement is proposed as a solution, comprising: a hollow shaft with an axis of rotation, wherein the hollow shaft is designed as a motor shaft for an electric motor and has a shaft tube and two journal elements connected to it at the ends, and a hub body which is frictionally connected to the hollow shaft and has a rotor lamination stack made of several rotor laminations, wherein the hollow shaft, viewed in cross-section, has a circumferentially closed wall with several support sections distributed around the circumference which are in contact with the hub body, and spring sections which are spaced apart from an inner circumferential surface of the hub body, wherein inner surface areas of the spring sections lie on a smaller radius around the axis of rotation than inner surface areas of the support sections.

[0014] One advantage is that the design of the hollow shaft with circumferentially distributed support sections and spring sections creates an interference fit that can compensate for even larger tolerances or operational deformations. Due to this interference fit, a force-fit connection is formed between the hub body and the hollow shaft, designed to reliably transmit the required torques under all operating conditions throughout the entire service life of the shaft assembly. Because of the circumferentially distributed spring sections, forces from these spring sections act circumferentially and radially on the respective support sections, which are thus pressed resiliently against the contact surface of the hub body. The hollow shaft therefore acts as a radial wave spring, which continues to exert radial forces on the hub body even in the event of elastic deformation of the hub body.This advantageously provides geometric compensation for dimensional and positional deviations as well as thermally and / or centrifugally induced deformations between the shaft and hub. Due to the radially elastic, spring-like effect of the shaft tube, a reliable frictional contact is always maintained between the support sections of the shaft tube and the contact surfaces of the hub body, allowing the manufacturing tolerances of the contacting surfaces to be kept relatively coarse. In particular, it is possible to forgo grinding the outer surface of the shaft and / or the inner surface of the hub body. In addition to the friction-fit connection between the shaft tube and hub body formed according to the invention, form-fit and / or material-fit connections can optionally be provided, which can preferably be arranged in the area of ​​the support sections.

[0015] The hub body is preferably pressed onto the hollow shaft to create a force-fit connection between the shaft and hub. In particular, the hub body can be connected to the hollow shaft via a longitudinal press fit or a transverse press fit. To create a longitudinal press fit, the hub is pressed onto the shaft seat under high axial force. To create a transverse press fit, the hub is heated and / or the shaft is cooled before assembly. This causes the hub to expand or the shaft to contract, respectively, allowing the two parts to be joined with reduced force. During the subsequent temperature equalization, the press fit is achieved, while the surface roughness is largely preserved. This results in a tighter fit than with a longitudinal press fit. Before assembly, the hollow shaft can have a surface roughness of at least 0.1 Rz and / or up to 1000 Rz, in particular from 1.0 Rz to 1000 Rz.The same applies to the surface roughness of the hub body, which can be at least 0.1 Rz and / or up to 1000 Rz, in particular from 1.0 Rz to 100 Rz.

[0016] The wall of the hollow shaft can have a constant thickness or a variable thickness around its circumference. In one embodiment, the wall of the hollow shaft is designed such that the smallest inner radius of the support sections is larger than the smallest inner radius of the spring sections. In other words, the support sections form absolute maxima of the wall thickness, while the intervening spring sections form absolute minima.

[0017] Technically, the spring sections on each side (in each circumferential direction) correspond to a bending beam subjected to a single load. By appropriately designing the geometric characteristics of the spring sections, such as thickness, curvature, and / or circumferential length, the spring behavior and thus the resulting spring characteristic of the hollow shaft, and consequently the radially elastic press fit between the shaft and hub, can be adjusted as required. The spring characteristic can be designed or set to be progressive, meaning the spring force increases with increasing spring travel; degressive, meaning the spring force decreases with increasing spring travel; or linear, meaning the spring force remains constant across the spring travel.

[0018] Designing the hollow shaft with a thicker wall and / or a shorter free bending length of the respective spring section between two circumferentially adjacent support sections results in higher stiffness and higher radial preload forces. Designing the hollow shaft with a thinner wall and / or a longer free bending length of the respective spring section between two circumferentially adjacent support sections results in lower stiffness and lower radial preload forces.

[0019] The number and extent of the support sections or spring sections also affect the spring behavior and thus the press fit between the shaft and hub. Preferably, the hollow shaft has three support sections and three spring sections arranged alternately around its circumference. This results in good centering and mutual support of the shaft and hub. However, it is understood that other numbers are also possible, such as two, four, five, six, or more support sections or spring sections, with an odd number being preferred for centering reasons. The support sections or spring sections are preferably arranged regularly around the circumference so that a uniform, force-fit connection is created around the circumference.

[0020] In one possible embodiment, the support sections, viewed in cross-section, can each extend over an angular range of at least 5°, preferably at least 30°. Alternatively or additionally, the support sections, viewed in cross-section, can each extend over a maximum angular range of up to 115°, preferably up to 90°.

[0021] The spring sections can each extend over an angular range of at least 5°, preferably at least 30°, when viewed in cross-section. Alternatively or additionally, the spring sections can each extend over a maximum angular range of up to 115°, preferably up to 90°, when viewed in cross-section.

[0022] In one possible embodiment, the spring sections can be designed such that, when the hub body is assembled, they are subject primarily to compressive stresses. This can be achieved by selectively adjusting the shaft's geometric shape with varying wall thicknesses to control the load within the shaft. This allows for the compensation of particularly damaging tensile stresses resulting from tangential bending by compressive stresses resulting from normal stress in the tangential direction. Specifically, the wall thickness in the support sections can be reduced compared to the spring sections to achieve a more favorable stress distribution. The maximum thickness of the spring sections can be, for example, at least 1.1 times, more specifically at least 1.2 times, and preferably at least 1.5 times, the minimum thickness of the support sections.Following a possible further development, the wall thickness within the support sections can be varied in the circumferential direction. The wall thickness in a central area of ​​the respective support section is preferably thinner than in the end areas of the support section (in each circumferential direction), which transition into the adjacent spring section.

[0023] The support sections preferably have an outer contour adapted to the inner contour of the hub body, which is particularly circular-cylindrical. This ensures a flat contact surface and thus frictional contact with the hub body over the entire circumferential length of the support sections. It is also possible that the outer contour of the hollow shaft, in its unassembled state, has absolute maxima in a circumferential region of the support sections, and that during the joining process, the support sections, starting from these absolute maxima, form a flat contact surface against the circular-cylindrical inner contour of the hub body in both circumferential directions. In the assembled state, the inner circumferential surface of the hollow shaft has a smaller distance to the axis of rotation in the circumferential regions of the spring sections than in the circumferential regions of the support sections.

[0024] The spring sections can each have a continuously increasing radial distance from the support sections adjacent to them in the circumferential direction to an imaginary circle with radius equal to the outer circumferential surface of the support sections or the inner circumferential surface of the hub body.

[0025] According to a preferred embodiment, the hollow shaft is designed such that the following applies to the radial spring travel (s3) of the hollow shaft: s3=(R3max−R3min)>Rp0.2*AE*π*D3a*(1−π*D3a22*A−μ) where R3max is the maximum radius of the shaft in its unassembled state, R3min is the maximum radius of the shaft in its maximum radially elastically compressed state, D3a is twice the maximum radius (R3max) of the shaft in its unassembled state, E is the Young's modulus of the shaft, A is the cross-sectional area of ​​the shaft, µ is Poisson's ratio of the shaft, and Rp0.2 is the yield strength of the shaft material. The spring travel of the hollow shaft can, for example, be set to more than 1.1 times, and in particular more than 1.2 times, the specified formulaic term. The greater the spring travel, the greater the achievable geometric compensation for dimensional and positional deviations as well as thermally and / or centrifugally induced deformations between the shaft and hub.

[0026] Alternatively or additionally, the hollow shaft can be designed such that the following applies to the spring rate (k3) of the hollow shaft: k3=FradU34<π*l34*E*(1−π*D3a22*A−μ)−1 where Frad is the effective radial force between the shaft and the hub body in the assembled state, U34 is the effective interference between the largest outside diameter (D3a) of the shaft and the smallest inside diameter (D4i) of the hub body in the unassembled state, E is the Young's modulus of the shaft, I 34 The length of the mating surface between the shaft and hub body, D3a twice the maximum radius (R3max) of the shaft in its unmounted state, and µ Poisson's ratio of the shaft are all given. The spring rate can be, for example, less than 0.9 times, and in particular less than 0.8 times, the specified formulaic term. A lower spring rate results in correspondingly lower loads in the contact area between the shaft and hub.

[0027] The shaft assembly can, in principle, be used for any application where torques need to be transmitted between a hub body and a shaft body. According to the invention, the hollow shaft is designed as a motor shaft for an electric motor, wherein the hub body has a rotor lamination stack consisting of several rotor laminations. Due to the radial spring action of the hollow shaft, the shaft assembly is able to ensure a secure, friction-fit connection to the hub even at high speeds of, for example, 1,500 rpm and above. However, the shaft assembly can also, in principle, be used for other applications not specified in the invention where torques need to be transmitted between a hub body and a shaft body.

[0028] The hollow shaft comprises a corrugated tube and two pin elements connected to its ends. At least one of the pin elements can have a connecting section for joining to an end section of the corrugated tube, wherein the circumferential contour of the connecting section is preferably adapted to the opposing contour of the corrugated tube, so that the pin element and the corrugated tube interlock positively. The connecting section can be inserted into the corrugated tube, in which case the circumferential contour is an outer contour that is adapted to the corresponding inner contour of the corrugated tube. Alternatively, the connection can also be configured in reverse, wherein the inner contour of the connecting section engages positively with the outer contour of the corrugated tube.

[0029] Preferred embodiments are explained below with reference to the drawing figures. Herein, we show Fig. 1A a wave arrangement according to the invention in a first embodiment in a three-dimensional view; Fig. 1B the wave arrangement from Fig. 1A in cross-section; Fig. 1C the hollow shaft of the shaft arrangement Fig. 1A as a detail in the cross-section Fig. 1D the hollow shaft from Fig. 1A and Fig. 1C in three-dimensional view; Fig. 1E the hollow shaft from Fig. 1D in perspective exploded view; Fig. 1F the wave arrangement from Fig. 1D perspective view during assembly; Fig. 2 a graphical representation of the transmissible maximum torque versus rotational speed of a shaft arrangement according to the invention, compared with a shaft arrangement according to the prior art; Fig. 3A a shaft arrangement according to the invention in a slightly modified embodiment in cross-section; Fig. 3B the hollow shaft of the shaft arrangement Fig. 3A in enlarged view with further details; Fig. 4A a shaft arrangement according to the invention in a further embodiment in cross-section; Fig. 4B the hollow shaft of the shaft arrangement Fig. 4A in three-dimensional representation; Fig. 5A a shaft arrangement according to the invention in a further embodiment in cross-section; Fig. 5B the hollow shaft of the shaft arrangement Fig. 5A in three-dimensional representation; Fig. 5C the hollow shaft from Fig. 5B in perspective exploded view; Fig. 6 a shaft arrangement according to the invention in a further embodiment in cross-section; Fig. 7 a shaft arrangement according to the invention in a further embodiment in cross-section; and Fig. 8 a shaft arrangement according to the invention in a further embodiment in cross-section.

[0030] The Fig. Figures 1A to 1E, which are described together below, show a shaft arrangement 2 according to the invention in a first embodiment. The shaft arrangement 2 comprises a hollow shaft 3 and a hub body 4, which are frictionally connected to one another. The frictional connection of the two components (3, 4) is effected in particular by means of an interference fit, whereby a longitudinal interference fit or a transverse interference fit can be used.

[0031] In cross-section, the hollow shaft 3 has a circumferentially closed wall 5 with several support sections 6 distributed around its circumference and alternating spring sections 7 in the circumferential direction. When the hub body 4 is mounted, the spring sections 7 are elastically pre-tensioned, so that they exert force on the support sections 6 located between them in the circumferential direction and in the radial direction. This results in the support sections 6 being in frictional contact with the hub body 4 under radial pre-tension, allowing a torque to be transmitted between the shaft and the hub.

[0032] Preferably, the spring sections 7 and the support sections 6 are identical in design and, in particular, symmetrical. Starting from a central area located midway between two circumferentially adjacent support sections 6, each spring section 7 forms a bending beam loaded with a point load in each circumferential direction. By appropriately designing the geometric characteristics of the spring sections 7, such as thickness, curvature, and / or circumferential length, the spring behavior and thus the press fit between shaft 3 and hub 4 can be adjusted according to the technical requirements regarding speed and torque.

[0033] The wall 5 of the hollow shaft is designed such that the inner circumferential surface 10 of the hollow shaft 3, viewed in cross-section, exhibits a maximum distance to the axis of rotation B in a circumferential region of the support sections 6 and a minimum distance to the axis of rotation B in a circumferential region of the spring sections 7. The smallest inner radius r6 of the support sections 6 can be larger than the smallest inner radius r7 of the spring sections 7. That is, the support sections 6 form absolute maxima of the wall 5, while the intermediate spring sections 7 form absolute minima.

[0034] In cross-section, the support sections 6 are in contact with the inner surface 9 of the hub body 4 over a certain circumferential extent via a support surface 8. Generally, the number and extent of the support sections 6, or the spring sections 7, influence the spring behavior and thus the preload force of the press fit between shaft 3 and hub 4. The support sections 6 have an outer contour 8 adapted to the inner contour 9 of the hub body 4, which in this case is circularly cylindrical.

[0035] The hollow shaft 3 is designed such that the support sections 6, in the unassembled state of the assembly, have a maximum outer radius R6max that is larger than the inner radius r4 of the hub 4. The maximum outer radius R6max is defined as the radius extending from the axis of rotation B to a point on the surface of the support sections 6 that is radially furthest away from it. The maximum outer radius of the shaft 3 resulting from the maximum outer radius R6max of the support sections 6 is designated as R3max. The outer contour of the support sections 6 may have an outer radius R8 that differs from the maximum radius R6max and, in the unassembled state of the hub, may also be slightly smaller than the inner radius r4 of the hub 4.The spring sections 7 can each have a continuously increasing radial distance from the support sections 6 adjacent to them in the circumferential direction to an imaginary circle K with radius R6max through the maximum of the support sections or to the circular cylindrical inner surface 9 with inner radius r4 of the hub 4.

[0036] It is particularly in the Fig. 1B and Fig. Figure 1C shows that the hollow shaft 3 in the present embodiment has three support sections 6 and three spring sections 7, which are alternately and regularly distributed around its circumference. This results in good centering and mutual support of the shaft and hub. The design with three support sections and three spring sections results in a division of 120° around the axis of rotation B. In cross-section, the support sections 6 each extend over an angular range α6 of approximately 60° to 90° around the axis of rotation, or are in contact with the inner surface 9 of the hub 4 over this angular range. In cross-section, the spring sections 7 each extend over an angular range α7 of approximately 30° to 60° in the circumferential direction. It is understood, however, that the shaft 3 can also have a different number of contact and spring sections 6, 7 than three, which would allow for correspondingly different circumferential lengths.

[0037] As especially from Fig. As shown in Figure 1E, the hollow shaft 3 comprises a corrugated tube 11 and two pin elements 13, 13' connected to its ends 12, 12'. Each pin element 13, 13' has a connecting section 14, 14' whose outer contour is adapted to the inner contour 15 of the corrugated tube 11. The pin elements 13, 13' are pressed into the ends of the corrugated tube 11, forming a positive-locking and force-locking connection. Other connection types, such as a material-locking connection (welding), are also possible. The corrugated tube 11, with the spring sections 7 provided therein, can be manufactured, for example, by drawing, internal high-pressure forming, or radial hammering or rotary swaging. In drawing, a round inlet tube with a constant wall thickness is drawn through a drawing die, which forms the cross-sectional contour of the shaft 3 and, if necessary, establishes a wall thickness that varies around the circumference.By selectively adjusting the drawing and annealing process, the strength of shaft 3 can be adjusted so that no subsequent hardening is necessary.

[0038] The surface roughness of the hollow shaft can range between 0.1 Rz and 1000 Rz before assembly, particularly between 1.0 Rz and 100 Rz. The same applies to the surface roughness of the hub body.

[0039] The hollow shaft can be designed so that its radial spring travel s3 is greater than: Rp0.2*AE*π*D3a*(1−π*D3a22*A−μ) and / or that its spring rate k3 is smaller than: π*l34*E*(1−π*D3a22*A−μ)−1

[0040] It is assumed that a possible geometric compensation between shaft 3 and hub 4 increases with increasing spring travel s3 and that the loads in the contact area between shaft and hub decrease accordingly with decreasing spring rate k3.

[0041] In Fig. Figure 2 shows the maximum torque transmissible by means of the shaft arrangement 2 according to the invention as a function of rotational speed (dashed line), compared to a shaft arrangement according to the prior art (dashed line).

[0042] It is evident that in a prior art shaft arrangement 102, the maximum transmissible torque Mmax decreases sharply with increasing rotational speed n. In contrast, the curve for the maximum transmissible torque Mmax of a shaft arrangement 2 according to the invention is significantly flatter, so that high torques can still be transmitted even at high rotational speeds. This is achieved by the circumferentially distributed spring sections 7 exerting spring forces on the respective intermediate support sections 6, which are thus pressed against the contact surface of the hub body 4. This results in a geometric adjustment to compensate for dimensional and positional deviations as well as thermally and centrifugally induced deformations between shaft 3 and hub 4, so that a secure force-fit connection between the components (3, 4) is maintained even at high rotational speeds.

[0043] The Fig. 3A and Fig. Figures 3B, which are described together below, show a shaft arrangement 2 according to the invention in a slightly modified embodiment. This corresponds largely to the embodiment according to the Fig. 1 and Fig. 2, so that reference is made to the above description regarding the similarities. Identical or corresponding details are marked with the same reference symbols, as in Fig. 1.

[0044] One difference lies in the shape of the spring sections 7, which have a slightly smaller circumferential extent α7 and are less deeply inwardly shaped. Correspondingly, the support sections 6 have a slightly larger circumferential extent α6 than in the embodiment described above. This results in greater stiffness of the hollow shaft 3, which in turn leads to greater forces in the press fit between the shaft 3 and the hub body 4.

[0045] The Fig. 4A and Fig. Figures 4B, which are described together below, show a shaft arrangement 2 according to the invention in a further embodiment. This largely corresponds to the embodiments according to the Fig. 1, Fig. 2 to Fig. 3, so that reference is made to the above description regarding the similarities. Identical or corresponding details are marked with the same reference symbols, as in the Fig. 1, Fig. 2 to Fig. 3.

[0046] In the present embodiment according to Fig. 4. The spring sections 7 are relatively short in the circumferential direction and, in particular, each have a circumferential extent α7 of less than 20°. Accordingly, the circumferential extent α6 of the support sections 8 is larger and in this case is more than 80° in each case.

[0047] The Fig. Figures 5A to 5C, which are described together below, show a shaft arrangement 2 according to the invention in a further embodiment. This largely corresponds to the embodiment according to Fig. 4, so that reference is made to the above description regarding the similarities. Identical or corresponding details are marked with the same reference symbols, as in the Fig. 1, Fig. 2, Fig. 3 to Fig. 4.

[0048] In the present embodiment according to Fig. 5. The spring sections 7 are relatively short in the circumferential direction and have a circumferential extent α7 of, in particular, less than 20° about the axis of rotation B. Furthermore, the spring sections 7 each have a relatively large radial extension inwards, which is a multiple of the wall thickness d of the corrugated tube 11, in particular at least three times the wall thickness. The spring sections 7 are U-shaped in cross-section and have two legs 16, 16' and a radially inward reversing section 17 that connects the two legs. As in the Fig. 5B and Fig. As can be seen in Figure 5C, the legs 16, 16' are further apart in the unmounted state of the hub 4 and diverge radially outwards. In the mounted state of the hub 4 according to Fig. In 5A, the legs 16, 16' of the spring sections 7 are elastically deformed towards each other, so that a spring preload exists between shaft 3 and hub 4. During the joining process, the shaft tube 11 is radially elastically compressed, resulting in a convex shape of the shaft 3 after the joining process. Alternatively, the convex shape can also be produced after the joining process by a permanent radial expansion of the shaft tube 11. As with the other embodiments, the hollow shaft 3 has a larger outer diameter than the inner diameter of the hub before the joining process with the hub 4.

[0049] Fig. Figure 6 shows a shaft arrangement 2 according to the invention in a further embodiment. This largely corresponds to the embodiments according to the Fig. 1, Fig. 2 to Fig. 3, so that reference is made to the above description regarding the similarities. Identical or corresponding details are marked with the same reference symbols, as in the Fig. 1, Fig. 2 to Fig. 3.

[0050] In the present embodiment according to Fig. In this embodiment, the wall 5 of the hollow shaft 3 has a thickness d5 that varies around its circumference. The mean and / or minimum wall thickness d6 in the support sections 6 is less than the mean and / or minimum wall thickness d7 in the spring sections 7. In the present embodiment, the wall thickness of the spring sections 7 is essentially constant in the circumferential direction, although a variable profile is also possible. The wall thickness of the support sections 6 is variable in the circumferential direction, particularly with continuous transitions. In cross-section, the wall thickness d6 in a central region of the respective support section 6 is thinner than in the end regions of the support section (in each circumferential direction) that transition into the adjacent spring section 7. The maximum and / or mean wall thickness d7 of the spring sections 7 is at least 1.5 times the minimum wall thickness d6 of the support sections 6.The circumferential extent of the spring sections 7, which are non-contacting the hub 4 when mounted, lies between 30° and 60° in this embodiment. The circumferential extent of the support sections 8, which are in contact with the hub 4 when mounted, lies between 60° and 90°.

[0051] In Fig. Figure 7 shows a further embodiment of a shaft arrangement 2 according to the invention. This largely corresponds to the embodiment according to Figure 7. Fig. 4, whose description is referenced in this respect. Identical details are marked with the same reference symbols.

[0052] In the present embodiment according to Fig. A tubular component 20 is provided, which is inserted into the corrugated tube 11 and causes an elastic or elastic-plastic deformation of the spring sections 7 by relative rotation. After the deformation of the spring sections 7, the component 20 remains in the corrugated tube 11 and can optionally be used for coolant guidance.

[0053] In Fig. Figure 8 shows a further embodiment of a shaft arrangement 2 according to the invention. This largely corresponds to the embodiment according to Figure 8. Fig. 4, whose description is referenced in this respect. Identical details are marked with the same reference symbols.

[0054] In the present embodiment according to Fig. 8. After assembly of the shaft tube 11 and hub body 4, the spring sections 7 are radially plastically deformed using a suitable spreading tool 30. This causes the connecting surfaces of the components 3 and 4 to press against each other with sufficient contact force.

[0055] As an alternative to the embodiments according to the Fig. 7 and Fig. 8. Another possible embodiment is in which the spring sections 7 are radially plastically deformed by means of internal high-pressure forming after the assembly of the wave tube 11 and hub body 4. Reference symbol list 2 shaft arrangement 3 Hollow shaft 4 hub bodies 5 wall 6 Support section 7 Spring section 8 Support surface 9 interior surface 10 Inner perimeter area 11 corrugated pipe 12, 12' End 13, 13' pin element 14, 14' Connection section 15 Inner contour 16, 16' thigh 17 Reversal section 20 components 30 Spreader tool α circumscribed angle A cross-sectional area B Longitudinal axis d wall thickness Diameter E E-module k spring rate M torque n rotational speed µ Poisson's ratio r inner radius R outer radius s suspension travel

Claims

[1] Wave arrangement comprising: a hollow shaft (3) with a rotation axis (B), wherein the hollow shaft is designed as a motor shaft for an electric motor and has a shaft tube (11) and two pin elements (13, 13') connected to it at the ends (12, 12'), a hub body (4) which is positively connected to the hollow shaft (3) and has a rotor lamination stack made up of several rotor laminations, wherein the hollow shaft (3) in cross-section has a circumferentially closed wall (5) with several support sections (6) distributed around the circumference, which are in contact with the hub body (4), and spring sections (7) which are spaced apart from an inner circumferential surface of the hub body (4), wherein inner surface areas of the spring sections (7) lie on a smaller radius around the axis of rotation (B) than inner surface areas of the support sections (6). [2] Shaft arrangement according to claim 1, characterized by, that a smallest inner radius (r6) of the support sections (6) is larger than a smallest inner radius (r7) of the spring sections (7). [3] Shaft arrangement according to claim 1 or 2, characterized by , that the support sections (6) extend in cross-section over an angular range (α6) of at least 5°, preferably at least 30°, and / or that the support sections (6) extend in cross-section over an angle range (α6) of up to 115°, preferably up to 90°. [4] Shaft arrangement according to any one of claims 1 to 3, characterized by , that the spring sections (7) extend in cross-section over an angular range (α7) of at least 5°, preferably at least 30°, and / or that the spring sections (7) extend in cross-section over an angular range (α7) of up to 115°, preferably up to 90°. [5] Shaft arrangement according to any one of claims 1 to 4, characterized by , that the wall (5) has a constant thickness (d5) around the circumference. [6] Shaft arrangement according to any one of claims 1 to 4, characterized by , that the wall (5) has a variable thickness (d5) around the circumference. [7] Shaft arrangement according to claim 6, characterized by , that the wall (5) in the support sections (6) has a smaller thickness (d6) than in the spring sections (7), wherein the wall (5) within the support sections (6) has a variable thickness (d6) in the circumferential direction. [8] Shaft arrangement according to claim 6 or 7, characterized by, that a maximum thickness (d7) of the spring sections (7) is at least 1.1 times greater than a minimum thickness (d6) of the support sections (6), in particular at least 1.5 times greater. [9] Shaft arrangement according to any one of claims 1 to 8, characterized by , that the hollow shaft (3) has at least three support sections (6) and at least three spring sections (7) arranged alternately around the circumference. [10] Shaft arrangement according to any one of claims 1 to 9, characterized by , that the support sections (6) have an outer contour adapted to the inner contour of the hub body (4), which is in particular circular cylindrical. [11] Shaft arrangement according to any one of claims 1 to 10, characterized by, that the spring sections (7) each have a continuously increasing radial distance from the support sections (6) adjacent to them in the circumferential direction to an imaginary circle (K) with radius (R8) of the outer circumferential surface (8) of the support sections (6). [12] Shaft arrangement according to any one of claims 1 to 11, characterized by , that the spring sections (7) are designed such that they are subject to essentially compressive stresses when the hub body (4) is mounted. [13] Shaft arrangement according to any one of claims 1 to 12, characterized by , that at least one of the pin elements (13, 13') has a connecting section (14, 14') for connecting to an end section (12, 12') of the corrugated tube (11), wherein the circumferential contour of the connecting section (14, 14') is adapted to the counter contour (15) of the corrugated tube (11) so that the pin element (13, 13') and the corrugated tube (11) interlock in a form-fitting manner. [14] Shaft arrangement according to any one of claims 1 to 13, characterized by , that the hollow shaft (3) has a surface roughness of at least 0.1 Rz and / or that the hub body (4) has a surface roughness of at least 0.1 Rz. [15] Shaft arrangement according to any one of claims 1 to 14, characterized by , that the hollow shaft (3) is designed such that it has a radial spring travel (s3) for which the following applies: s3=(R3max−R3min)>Rp0.2*AE*π*D3a*(1−π*D3a22*A−μ) where R3max is the maximum radius of the shaft (3) in its unassembled state, R3min is the maximum radius of the shaft (3) in its maximally radially elastically compressed state, D3a twice the maximum radius (R3max) of the shaft (3) in the unassembled state, E the modulus of elasticity of the shaft (3), A the cross-sectional area of ​​the shaft (3) µ the Poisson's ratio of the wave (3) Rp0,2 is the yield strength of the material of the shaft (3). [16] Shaft arrangement according to any one of claims 1 to 15, characterized by , that the hollow shaft (3) is designed to have a spring rate (k3), The following applies to: k3=FradU34<π*l34*E*(1−π*D3a22*A−μ)−1 where Frad the effective radial forces between shaft (3) and hub body (4) in the assembled state, U34 the effective interference between the largest outer diameter (D3a) of the shaft (3) and the smallest inner diameter (D4i) of the hub body (4) in the unassembled state, E the modulus of elasticity of the shaft (3), I 34 the length of the joining surface between shaft (3) and hub body (4), D3a twice the maximum radius (R3max) of the shaft (3) in the unassembled state and µ the Poisson's ratio of the wave (3) are.

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