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 connecting arrangement with a shaft and a hub, in particular for an electric machine of a motor vehicle.

[0002] DE 102 24 477 A1 discloses a detachable shaft-hub connection comprising 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 hub and firmly connected to it, each of which has a spring arm resting against the hub or shaft under preload.

[0003] A rotor and a manufacturing method therefor are known from DE 10 2010 039 008 A1. The rotor comprises 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 region whose shape describes a circular cylinder, as well as a second surface region formed by structural elements that rise radially outward above the first surface region with respect to the rotor axis.

[0004] DE 195 21 755 C1 discloses a connection system for detachably connecting two components. For this purpose, one component is temporarily deformed during the connection process so that an effective circumferential contour corresponds to the corresponding circumferential contour of the other component with a specified clearance. After both components are positioned, a firm pressure contact between the two effective circumferential contours is created by at least partial reshaping.

[0005] WO 99 65643 A1 discloses a method for producing a detachable connection between a hollow body and a shaft. In this process, 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 plugged into one another. After plugging the two components together, a pressure connection is established by elastically reshaping the hollow body by reducing the radial compressive forces.

[0006] A rotor for an electric machine is known from DE 10 2015 012 912 A1. The rotor comprises a rotor shaft and several plate packs secured thereto in a form-fitting manner. The rotor shaft has several form-fitting elements and is non-circular in cross-section in the area of ​​the plate packs to form the form-fitting elements.

[0007] DE 10 2016 202 416 A1 discloses a rotor shaft assembly for an electric motor rotor. The assembly comprises a hollow shaft for receiving a rotor body and a heat sink arranged in the hollow shaft.

[0008] DE 10 2016 215 760 A1 discloses a rotor for an electric motor of a vehicle. The rotor has a central shaft and a laminated core arranged between two retaining discs.

[0009] It is known to press-fit a hub body onto a shaft so that torque can be transmitted between the two components. Depending on the technical requirements, the respective diameters of the shaft and hub must be manufactured with high precision. At high speeds in the shaft-hub connection arrangement, this can lead to a reduction in the press-fit forces.

[0010] It is an object of the present invention to propose a connecting arrangement with a shaft and a hub which ensures reliable torque transmission even at high speeds and which can be produced easily and inexpensively.

[0011] To solve this problem, a shaft arrangement is proposed, comprising: a hollow shaft with an axis of rotation and a hub body which is non-positively connected to the hollow shaft, wherein the hollow shaft, viewed in cross section, has a circumferentially closed wall with a plurality of support sections distributed over the circumference, which are in abutting contact with the hub body, and spring sections which are spaced from an inner circumferential surface of the hub body, wherein inner surface regions of the spring sections lie on a smaller radius around the axis of rotation than inner surface regions of the support sections.

[0012] 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. The interference fit creates a force-locking connection between the hub body and the hollow shaft, designed to reliably transmit the desired torques under all operating conditions over the entire service life of the shaft assembly. Due to the circumferentially distributed spring sections, forces act in the circumferential and radial directions on the support sections located between them, which are thus resiliently pressed 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 when the hub body is elastically deformed.This advantageously provides geometric compensation to compensate for dimensional and positional deviations as well as thermally and / or centrifugal force-induced deformations between the shaft and hub. Due to the radially elastic, resilient effect of the shaft tube, a secure frictional contact is always formed between the support sections of the shaft tube and the contact surfaces of the hub body, so that the manufacturing tolerances of the contacting surfaces can be kept relatively coarse. In particular, it is possible to dispense with grinding of the outer surface of the shaft and / or the inner surface of the hub body. In addition to the force-fitting connection between the shaft tube and the hub body formed according to the invention, form-fitting and / or material-fitting connections can also be provided optionally, which can preferably be arranged in the region of the support sections.

[0013] The hub body is preferably pressed onto the hollow shaft to create a frictional connection between the shaft and hub. In particular, the hub body can be connected to the hollow shaft in a longitudinal interference fit or a transverse interference fit. To create a longitudinal interference fit, the hub is pressed onto the shaft seat under high axial force. To create a transverse interference fit, the hub is heated and / or the shaft is cooled before assembly. This causes the hub to expand or the shaft to shrink, allowing the two parts to be joined with reduced force. During the subsequent temperature equalization, the compression is established, with the surface roughness being largely retained. This results in a tighter fit than with a longitudinal interference 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 100 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.

[0014] The wall of the hollow shaft can have a constant thickness or a variable thickness over its circumference. According to 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, while the intermediate spring sections form absolute minima.

[0015] Technically speaking, the suspension sections on both sides (in each circumferential direction) correspond to a bending beam loaded with a single load. By appropriately designing the geometric conditions of the suspension sections, such as thickness, curvature, and / or circumferential length, the suspension behavior and thus the resulting spring characteristic of the hollow shaft, and thus the radially elastic interference fit between the shaft and hub, can be adjusted as required. The spring characteristic can be designed or adjusted 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 over the spring travel.

[0016] If the hollow shaft is designed with a thicker wall and / or a shorter free bending length of the respective suspension section between two circumferentially adjacent support sections, greater rigidity and higher radial preload forces are achieved. If the hollow shaft is designed with a thinner wall and / or a longer free bending length of the respective suspension section between two circumferentially adjacent support sections, lower rigidity and lower radial preload forces are achieved.

[0017] The number and extent of the support sections or suspension sections also affect the suspension behavior and thus the press fit between shaft and hub. The hollow shaft preferably has three support sections and three spring sections, which are arranged alternately around the circumference. This results in good centering and mutual support of shaft and hub. However, it is understood that other numbers are also possible, such as two, four, five, six or more support sections or suspension sections, with an odd number being preferred for centering reasons. The support sections or suspension sections are preferably arranged evenly distributed around the circumference, so that a uniform force-fitting connection is created around the circumference.

[0018] According to one possible embodiment, the support sections can each extend over an angular range of at least 5°, preferably at least 30°, viewed in cross-section. Alternatively or additionally, the support sections can each extend over a maximum angular range of up to 115°, preferably up to 90°, viewed in cross-section.

[0019] The spring sections can each extend over an angular range of at least 5°, preferably at least 30°, 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°, viewed in cross-section.

[0020] According to a possible embodiment, the spring sections can be designed such that they are essentially subject to compressive stresses when the hub body is assembled. For this purpose, the load in the shaft can be adjusted by specifically adjusting the geometric shape of the shaft with varying wall thicknesses such that tensile stresses resulting from tangential bending, which are particularly harmful to failure, can be compensated for by compressive stresses resulting from normal stress in the tangential direction. In particular, for a particularly favorable stress distribution, the wall can have a thinner thickness in the support sections than in the spring sections. The maximum thickness of the spring sections can, for example, be at least 1.1 times, in particular at least 1.2 times, preferably at least 1.5 times the minimum thickness of the support sections.According to a possible refinement, the wall thickness within the support sections can be designed to be variable in the circumferential direction. The wall thickness is preferably thinner in a central region of the respective support section than in the end regions of the support section (in each circumferential direction) that transition into the adjacent suspension section.

[0021] The support sections preferably have an outer contour adapted to the inner contour of the hub body, which is in particular circular-cylindrical. This provides a flat contact and thus frictional contact with the hub body over the entire circumferential length of the support sections. It is also possible for the outer contour of the hollow shaft, in the unassembled state, to have absolute maxima in a circumferential area of ​​the support sections and for the support sections, during the joining process, to lie flat against the circular-cylindrical inner contour of the hub body in both circumferential directions, starting from the absolute maxima. In the assembled state, the inner circumferential surface of the hollow shaft has a smaller distance from the axis of rotation in the circumferential areas of the spring sections than in the circumferential areas of the support sections.

[0022] The spring sections can each have, starting from the support sections adjacent to them in the circumferential direction, a continuously increasing radial distance from an imaginary circular line with a radius of the outer circumferential surface of the support sections or the inner circumferential surface of the hub body.

[0023] According to a preferred embodiment, the hollow shaft is designed so that the radial spring travel (s3) of the hollow shaft is: s3=(R3max−R3min)>Rp0.2∗AE∗π∗D3a∗(1−π∗D3a22∗A−μ) where R3max is the maximum radius of the shaft in the unassembled state, R3min is the maximum radius of the shaft in the maximum radially elastically compressed state, D3a is twice the maximum radius (R3max) of the shaft in the unassembled state, E is the E-modulus of the shaft, A is the cross-sectional area of ​​the shaft, µ is the 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 formula term. The greater the spring travel, the greater the achievable geometric compensation to compensate for dimensional and positional deviations as well as thermal and / or centrifugal force-induced deformations between the shaft and hub.

[0024] Alternatively or in addition, the hollow shaft can be designed so that the spring rate (k3) of the hollow shaft is: k3=FradU34<π∗l34∗E∗(1−π∗D3a22∗−μ)−1 where Frad is the effective radial force between shaft and hub body in assembled condition, 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 unassembled condition, E is the modulus of elasticity of the shaft, I 34 is the length of the joint surface between the shaft and the hub body, D3a is twice the maximum radius (R3max) of the shaft in the unassembled state, and µ is the Poisson's ratio of the shaft. The spring rate can, for example, be less than 0.9 times, and in particular less than 0.8 times, the specified formula term. A lower spring rate leads to correspondingly lower loads in the contact area between the shaft and hub.

[0025] The shaft assembly can, in principle, be used for any application in which torque must be transmitted between a hub body and a shaft body. For example, the hollow shaft can be designed as a motor shaft for an electric motor, in which case the hub body can have a rotor core consisting of several rotor laminations. Due to the radial spring action of the hollow shaft, the shaft assembly is capable of ensuring a secure, frictional connection to the hub even at high speeds of, for example, 1,500 rpm and more.

[0026] The hollow shaft can have a shaft tube and two journal elements connected to it at its ends. At least one of the journal elements can have a connecting section for connection to an end section of the shaft tube, wherein the circumferential contour of the connecting section is preferably adapted to the mating contour of the shaft tube, so that the journal element and the shaft tube engage in a form-fitting manner. The connecting section can be inserted into the shaft tube, in which case the circumferential contour is an outer contour that is adapted to the matching inner contour of the shaft tube. Alternatively, the connection can also be designed inversely, wherein the inner contour of the connecting section engages in a form-fitting manner with the outer contour of the shaft tube.

[0027] Preferred embodiments are explained below with reference to the drawing figures. Fig. 1A shows a shaft arrangement according to the invention in a first embodiment in three-dimensional view; Fig. 1B the shaft arrangement from Fig. 1A in cross section; Fig. 1C the hollow shaft of the shaft assembly Fig. 1A as a detail in cross section Fig. 1D the hollow shaft Fig. 1A and Fig. 1C in three-dimensional view; Fig. 1E the hollow shaft from Fig. 1D in perspective exploded view; Fig. 1F the shaft arrangement from Fig. 1D in perspective view during assembly; Fig. 2 a graphical representation of the maximum transmittable torque versus speed of a shaft arrangement according to the invention, compared with a shaft arrangement according to the prior art; Fig. 3A shows a shaft arrangement according to the invention in a slightly modified embodiment in cross section; Fig. 3B the hollow shaft of the shaft assembly Fig. 3A in an enlarged view with further details; Fig. 4A shows a shaft arrangement according to the invention in a further embodiment in cross section; Fig. 4B the hollow shaft of the shaft assembly Fig. 4A in three-dimensional representation; Fig. 5A shows a shaft arrangement according to the invention in a further embodiment in cross section; Fig. 5B the hollow shaft of the shaft assembly Fig. 5A in three-dimensional representation; Fig. 5C the hollow shaft 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.

[0028] The Fig. 1A to 1E, which are described together below, show a first embodiment of a shaft assembly 2 according to the invention. The shaft assembly 2 comprises a hollow shaft 3 and a hub body 4, which are non-positively connected to one another. The non-positive connection of the two components (3, 4) is achieved in particular by means of an interference fit, whereby a longitudinal interference fit or a transverse interference fit can be used.

[0029] Viewed in cross-section, the hollow shaft 3 has a circumferentially closed wall 5 with several support sections 6 distributed around the circumference and spring sections 7 alternating in the circumferential direction. When the hub body 4 is assembled, the spring sections 7 are elastically preloaded, so that they exert circumferential and radial pressure on the support sections 6 located between them. As a result, the support sections 6 are in frictional contact with the hub body 4 under radial preload, allowing torque to be transmitted between the shaft and the hub.

[0030] Preferably, the suspension sections 7 and the support sections 6 are each designed identically to one another and, in particular, are each symmetrical. Starting from a central region located midway between two circumferentially adjacent support sections 6, the suspension sections 7 each form a bending beam loaded with a single load in each circumferential direction. By appropriately designing the geometric conditions of the suspension sections 7, such as thickness, curvature, and / or circumferential length, the suspension behavior and thus the interference fit between shaft 3 and hub 4 can be adjusted according to the technical requirements with regard to speed and torque.

[0031] The wall 5 of the hollow shaft is designed in particular such that the inner circumferential surface 10 of the hollow shaft 3, viewed in cross-section, has a maximum distance from the axis of rotation B in a circumferential region of the support sections 6 and a minimum distance from the axis of rotation B in a circumferential region of the spring sections 7. A smallest inner radius r6 of the support sections 6 can be larger than a smallest inner radius r7 of the spring sections 7. This means that the support sections 6 form absolute maxima of the wall 5, while the intermediate spring sections 7 form absolute minima.

[0032] Viewed in cross-section, the support sections 6 are in contact with the inner surface 9 of the hub body 4 via a support surface 8 over a certain circumferential extent. In general, the number and extent of the support sections 6 or the suspension sections 7 influence the suspension behavior and thus the preload force of the interference fit between the shaft 3 and the hub 4. The support sections 6 have an outer contour 8 adapted to the inner contour 9 of the hub body 4, with the inner contour 9 of the hub body 4 being circular-cylindrical in this case.

[0033] The hollow shaft 3 is designed such that the support sections 6, in the unassembled state of the arrangement, have a maximum outer radius R6max that is greater than the inner radius r4 of the hub 4. The maximum outer radius R6max is understood to be the radius that extends 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, which results from the maximum outer radius R6max of the support sections 6, is designated R3max. The outer contour of the support sections 6 can have an outer radius R8 that deviates from the maximum radius R6max, which, in the unassembled state of the hub, can in particular also be slightly smaller than the inner radius r4 of the hub 4.The spring sections 7 can each have, starting from the support sections 6 adjacent thereto in the circumferential direction, a continuously increasing radial distance from an imaginary circular line K with radius R6max through the maximum of the support sections or from the circular cylindrical inner surface 9 with inner radius r4 of the hub 4.

[0034] It is particularly in the Fig. 1B and Fig. 1C 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 over the 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 respective pitch of 120° around the axis of rotation B. The support sections 6, viewed in cross section, 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 the aforementioned angular range. The spring sections 7, viewed in cross section, 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 number of support and spring sections 6, 7 other than three, whereby correspondingly different circumferential lengths are possible.

[0035] As is particularly evident from Fig. As can be seen from Figure 1E, the hollow shaft 3 comprises a shaft tube 11 and two journal elements 13, 13' connected to it at the ends 12, 12'. The journal elements 13, 13' each have a connecting section 14, 14', the outer contour of which is adapted to the inner contour 15 of the shaft tube 11. The journal elements 13, 13' are pressed into the ends of the shaft tube 11 and form a positive and non-positive connection therewith, although other connection types, such as a material connection (welding), are also possible. The shaft tube 11 can be manufactured with the spring sections 7 provided therein, for example, by drawing, internal high-pressure forming, or radial hammering or rotary swaging. During drawing, a round input tube with a constant wall thickness is drawn through a drawing tool, which forms the cross-sectional contour of the shaft 3 and, if necessary, sets a wall thickness that varies over the circumference.By carefully adjusting the drawing and annealing process, the strength of shaft 3 can be adjusted so that no subsequent hardening is necessary.

[0036] The surface roughness of the hollow shaft before assembly can be between 0.1 Rz and 1000 Rz, in particular between 1.0 Rz and 100 Rz. The same applies to the surface roughness of the hub body.

[0037] 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 their spring rate k3 is less than: π∗l34∗E∗(1−π∗D3a22∗A−μ)−1

[0038] It is important to note that a possible geometry 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.

[0039] In Fig. 2, the maximum torque that can be transmitted by means of the shaft arrangement 2 according to the invention is shown graphically over the speed (dash-dotted line), compared with a shaft arrangement according to the prior art (dashed line).

[0040] It can be seen that in a shaft arrangement 102 according to the prior art, the maximum transmittable torque Mmax decreases sharply with increasing speed n. In contrast, the curve for the maximum transmittable torque Mmax of a shaft arrangement 2 according to the invention falls much more gently, so that high torques can still be transmitted even at high speeds. This is achieved in that the circumferentially distributed spring sections 7 exert spring forces on the support sections 6 located between them, which are thus pressed against the contact surface of the hub body 4. This results in a geometric compensation to compensate for dimensional and positional deviations as well as thermal and centrifugal force-induced deformations between the shaft 3 and hub 4, so that a secure, force-fitting connection between the components (3, 4) is maintained even at high speeds.

[0041] The Fig. 3A and Fig. 3B, which are described together below, show a shaft arrangement 2 according to the invention in a slightly modified embodiment. This largely corresponds to the embodiment according to the Fig. 1 and Fig. 2, so that with regard to the similarities, reference is made to the above description. Identical or corresponding details are provided with the same reference numerals as in Fig. 1.

[0042] One difference lies in the shape of the spring sections 7, which have a slightly smaller circumferential extent α7 and are less strongly formed inward. Accordingly, the support sections 6 have a slightly larger circumferential extent α6 than in the above embodiment. This results in greater rigidity of the hollow shaft 3, which correspondingly leads to greater forces in the interference fit between the shaft 3 and the hub body 4.

[0043] The Fig. 4A and Fig. 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 to 3, so that with regard to the similarities, reference is made to the above description. The same or corresponding details are provided with the same reference numerals as in the Fig. 1 to 3.

[0044] 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 extension α7 of less than 20°. Accordingly, the circumferential extension α6 of the support sections 8 is larger and, in this case, amounts to more than 80° each.

[0045] The Fig. 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 with regard to the similarities, reference is made to the above description. The same or corresponding details are provided with the same reference numerals as in the Fig. 1 to 4.

[0046] In the present embodiment according to Fig. 5, the spring sections 7 are relatively short in the circumferential direction and have a circumferential extension α7 of, in particular, less than 20° around the rotation axis B. Furthermore, the spring sections 7 each have a relatively large radial extension inward, which is a multiple of the wall thickness d of the shaft 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 inner reversing section 17, which connects the two legs to each other. As shown in the Fig. 5B and Fig. 5C, the legs 16, 16' are further apart from each other in the unassembled state of the hub 4 and diverge radially outwards. In the assembled state of the hub 4 according to Fig. 5A, the legs 16, 16' of the spring sections 7 are elastically deformed toward each other, creating a spring preload between the shaft 3 and the hub 4. During the joining process, the shaft tube 11 is compressed radially and elastically, resulting in a spherical shape of the shaft 3 after the joining process. Alternatively, the spherical shape can also be created 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.

[0047] Fig. Figure 6 shows a further embodiment of a shaft arrangement 2 according to the invention. This largely corresponds to the embodiments according to Fig. 1 to 3, so that with regard to the similarities, reference is made to the above description. The same or corresponding details are provided with the same reference numerals as in the Fig. 1 to 3.

[0048] In the present embodiment according to Fig. 6, the wall 5 of the hollow shaft 3 has a thickness d5 that varies around its circumference. An average and / or minimum wall thickness d6 in the support sections 6 is smaller than an average 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, in particular with continuous transitions. Viewed in cross-section, the wall thickness d6 is thinner in a central region of the respective support section 6 than in the end regions of the support section (in each circumferential direction) that transition into the respective adjacent spring section 7. The largest and / or average wall thickness d7 of the spring sections 7 is at least 1.5 times the smallest wall thickness d6 of the support sections 6.The circumferential extent of the spring sections 7, which are non-contacting with the hub 4 in the assembled state, is between 30° and 60° in this embodiment. The circumferential extent of the support sections 8, which are in abutting contact with the hub 4 in the assembled state, is between 60° and 90°.

[0049] In Fig. 7 shows a further embodiment of a shaft arrangement 2 according to the invention. This largely corresponds to the embodiment according to Fig. 4, to whose description reference is made. Identical details are provided with identical reference numerals.

[0050] In the present embodiment according to Fig. 7, a tubular component 20 is provided, which is inserted into the shaft tube 11 and, through relative rotation, causes an elastic or elastic-plastic deformation of the spring sections 7. The component 20 remains in the shaft tube 11 after the deformation of the spring sections 7 and can, if necessary, be used for a coolant guide.

[0051] In Fig. 8 shows a further embodiment of a shaft arrangement 2 according to the invention. This largely corresponds to the embodiment according to Fig. 4, to whose description reference is made. Identical details are provided with identical reference numerals.

[0052] In the present embodiment according to Fig. 8, after the shaft tube 11 and hub body 4 have been assembled, the spring sections 7 are radially plastically deformed using a suitable expanding tool 30. This causes the connecting surfaces of the components 3, 4 to contact each other with sufficient contact force.

[0053] Alternatively to the embodiments according to the Fig. 7 and Fig. 8, an embodiment is also conceivable in which the spring sections 7 are radially plastically deformed by means of internal high-pressure forming after the assembly of the shaft tube 11 and the hub body 4. List of reference symbols 2 shaft arrangement 3 hollow shaft 4 hub bodies 5 Wall 6 support section 7 spring section 8 Support surface 9 Inner surface 10 inner peripheral surface 11 Corrugated tube 12, 12' End 13, 13' tenon element 14, 14' connecting section 15 Inner contour 16, 16' thigh 17 Reversal section 20 components 30 Spreading tool α circumferential angle A cross-sectional area B Longitudinal axis d wall thickness D Diameter E E-modulus k spring rate M torque n speed µ Poisson's ratio r inner radius R outer radius s suspension travel QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102 24 477 A1

[0002] DE 10 2010 039 008 A1

[0003] DE 195 21 755 C1

[0004] WO 99 65643 A1

[0005] DE 10 2015 012 912 A1

[0006] DE 10 2016 202 416 A1

[0007] DE 10 2016 215 760 A1

[0008]

Claims

[1] Shaft arrangement comprising: a hollow shaft (3) with a rotational axis (B), wherein the hollow shaft is designed as a motor shaft for an electric motor and has a shaft tube (11) and two journal elements (13, 13') connected to it at the ends (12, 12'), a hub body (4) which is non-positively connected to the hollow shaft (3) and has a rotor lamination package consisting of several rotor laminations, wherein the hollow shaft (3), viewed in cross-section, has a circumferentially closed wall (5) with a plurality of support sections (6) distributed over the circumference, which are in contact with the hub body (4), and spring sections (7) which are spaced 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) each extend over an angular range (α6) of at least 5°, preferably at least 30°, when viewed in cross section, and / or that the support sections (6) each extend over an angular range (α6) of up to 115°, preferably up to 90°, when viewed in cross section. [4] Shaft arrangement according to one of claims 1 to 3, characterized by , that the spring sections (7) each extend over an angular range (α7) of at least 5°, preferably at least 30°, when viewed in cross section, and / or that the spring sections (7) each extend over an angular range (α7) of up to 115°, preferably up to 90°, when viewed in cross section. [5] Shaft arrangement according to one of claims 1 to 4, characterized by , that the wall (5) has a constant thickness (d5) over the circumference. [6] Shaft arrangement according to one of claims 1 to 4, characterized by , that the wall (5) has a variable thickness (d5) over 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) each 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 as large as a minimum thickness (d6) of the support sections (6), in particular at least 1.5 times as large. [9] Shaft arrangement according to 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) which are arranged alternately over the circumference. [10] Shaft arrangement according to 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 one of claims 1 to 10, characterized by , that the spring sections (7) each have, starting from the support sections (6) adjacent thereto in the circumferential direction, a continuously increasing radial distance from an imaginary circular line (K) with radius (R8) of the outer circumferential surface (8) of the support sections (6). [12] Shaft arrangement according to one of claims 1 to 11, characterized by , that the spring sections (7) are designed in such a way that they are essentially subject to compressive stresses when the hub body (4) is in the assembled state. [13] Shaft arrangement according to 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 shaft tube (11), wherein the circumferential contour of the connecting section (14, 14') is adapted to the counter contour (15) of the shaft tube (11), so that the pin element (13, 13') and the shaft tube (11) engage in a form-fitting manner. [14] Shaft arrangement according to 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 one of claims 1 to 14, characterized by , that the hollow shaft (3) is designed so 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 unassembled condition, R3min is the maximum radius of the shaft (3) in maximum radial-elastically compressed state, D3a twice the maximum radius (R3max) of the shaft (3) in unassembled condition, E is the modulus of elasticity of the shaft (3), A is the cross-sectional area of ​​the shaft (3) µ is the Poisson’s ratio of the shaft (3) Rp0.2 is the yield strength of the material of the shaft (3). [16] Shaft arrangement according to one of claims 1 to 15, characterized by , that the hollow shaft (3) is designed to have a spring rate (k3), for which the following applies: 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 assembled state, U34 is the effective interference between the largest outside diameter (D3a) of the shaft (3) and the smallest inside diameter (D4i) of the hub body (4) in the unassembled state, E is the modulus of elasticity of the shaft (3), I 34 the length of the joining surface between shaft (3) and hub body (4), D3a is twice the maximum radius (R3max) of the shaft (3) in unassembled condition and µ is the Poisson's ratio of the shaft (3) are.

Images