SHAFT, HUB, AND SHAFT-HUB CONNECTION, AND ELECTRICAL ACTUATOR

Description

[0001] The invention relates to a shaft for transmitting a torque and / or an axial force, a hub, a shaft-hub connection and an electrical actuator.

[0002] Numerous shaft-hub connections for a wide variety of applications are known in the prior art. The following are cited as prior art in printed documents: EP 2 058 542 A2, EP 1 632 331 A1, EP 2 287 484 A2, DE 10 2016 211797 A1, and DE 102 38 968 A1. In the field of electrical actuators, such as electric brake boosters, it is particularly well known to connect a spindle-shaped shaft at one end to a hub-shaped hub in order to fix the spindle relative to a machine element moving relative to it. The connection between the spindle and the hub must therefore be able to transmit torques acting about the spindle's longitudinal axis as well as axial forces acting along the spindle's longitudinal axis. Sometimes, the requirement is that such shaft-hub connections may only occupy a limited installation space.

[0003] Such connections have previously been achieved using a weld connecting the spindle to the plate. However, this type of connection requires that both parts be made of materials suitable for welding. Suitable materials and surfaces, however, have disadvantages with regard to corrosion resistance. Furthermore, the components must be cleaned of oil residue before welding, as oil residue generally has a negative impact on the weld's properties.

[0004] The invention is therefore based on the objective of providing a reliable and robust connection between a shaft and a hub that requires little installation space and can be manufactured cost-effectively. The invention is also based on the objective of providing a shaft and a hub for such a connection. Furthermore, the invention is based on the objective of providing a high-quality electrical actuator that requires little installation space and can be manufactured cost-effectively.

[0005] The problem is solved according to the invention by a shaft with the features of claim 1, a hub with the features of claim 9, a shaft-hub connection with the features of claim 13 and an electrical actuator with the features of claim 17.

[0006] Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0007] A shaft according to the invention for transmitting a torque and / or an axial force comprises a longitudinal shaft axis, a shaft surface, and a shaft end. The shaft surface has at least one recess with an axial recess wall and a radial recess wall adjacent to the axial recess wall. The axial recess wall is particularly suitable for transmitting axial forces. The radial recess wall is particularly suitable for transmitting torques acting about the longitudinal shaft axis. The radial recess wall is preferably arranged parallel to the longitudinal shaft axis. The axial recess wall, in turn, is preferably arranged perpendicular to the radial recess wall.The radial recess wall preferably borders the axial recess wall in such a way that a shaft-side transition radius is arranged at the transition from the radial recess wall to the axial recess wall, which can particularly serve to reduce notch stresses.

[0008] The radial recess wall has a first wall end and a second wall end. Each of the wall ends is preferably formed by a line of intersection between the radial recess wall and the corrugated surface.

[0009] The at least one recess is axially open towards the shaft end. A corresponding axial opening is thus preferably arranged opposite the axial recess wall. Therefore, the shaft preferably has no section extending axially from the shaft end that would at least partially obscure the at least one recess. Preferably, a hub with an element engaging in the at least one recess can be pushed onto the shaft from the shaft end until the engaging element abuts the axial recess wall.

[0010] Unless otherwise specified, the terms "axial" and "radial" here and in the following refer preferably to the longitudinal axis of the shaft and / or the longitudinal axis of the hub.

[0011] According to the invention, the radial recess wall has a recess radius such that the radial recess wall has, at least in sections, a concave recess arc shape facing away from the longitudinal axis of the shaft. This makes the radial recess wall particularly suitable for transmitting torques acting about the longitudinal axis of the shaft. Due to the concave recess arc shape facing away from the longitudinal axis of the shaft, the at least one recess is preferably trough-shaped from the perspective of the shaft's surface. In particular, the radial recess wall can deviate from an imaginary straight line connecting the first and second wall ends due to the concave recess arc shape. The design of the radial recess wall according to the invention preferably does not preclude a design such that the radial recess wall is straight in sections.For example, the radial recess wall can comprise several straight sections that are angularly offset from each other and can be connected by an arc-shaped section. The angular offset can be in the range between 90° and 180°.

[0012] In a preferred embodiment of the invention, the arc-shaped recess of the radial recess wall extends from the first wall end to the second wall end and / or the recess radius is variable. If the arc-shaped recess of the radial recess wall extends from the first wall end to the second wall end, the entire radial recess wall is preferably arc-shaped, so that the radial recess wall is free of a straight section in the direction from the first wall end to the second wall end. If the recess radius is variable, it is preferably not constant. The radial recess wall is thus preferably not constantly curved. The variable design of the recess radius allows for a more uniform transmission of torque across the radial recess wall, thereby reducing the stress, particularly on the contact surfaces involved.It is particularly preferred that the recess radius is larger than the outer radius of the shaft.

[0013] The recess arc shape of the radial recess wall is particularly preferably defined as corresponding to at least one segment of a hypotrochoid. This is preferably a contour that is easy and quick to manufacture and can enable uniform torque transmission. Here and in the following, a hypotrochoid is preferably understood to be a path described by a point located on a circle as this circle rolls within another circle, the so-called base circle. The point in question can lie either outside or inside the rolling circle.

[0014] In parametric form, the hypotrochoid can be described using the following set of formulas: x θ = R − r cos θ + d cos R − r r θ y θ = R − r sin θ − d sin R − r r θ

[0015] Here, R is the radius of the base circle, r is the radius of the rolling circle, and d is the distance of the point from the center of the rolling circle. The parameter d can thus be considered a measure of the eccentricity. The ratio R / r is preferably chosen to be a natural number. In this case, the ratio can particularly indicate the number of so-called vertices of the hypotrochoid. Preferably, the ratio R / r is at least 3. A ratio of R / r = 4 is particularly preferred.

[0016] The hypotrochoid's center point is preferably located on the longitudinal axis of the shaft. The ratio R / r thus preferably corresponds to the number of recesses. The recesses can therefore be distributed evenly and symmetrically around the circumference of the shaft. The shaft can be designed such that the corners of the hypotrochoid are located outside the shaft. In a corresponding embodiment of the invention, the corners are therefore not directly formed within the recess arc shape.

[0017] According to the invention, the shaft's outer surface has a spindle toothing with at least one spindle tooth. Preferably, the at least one spindle tooth runs helically around the shaft along its longitudinal axis. The shaft can thus function as a spindle, for example, of a spindle drive.

[0018] The axial recess wall of at least one of the at least one recess can be formed, at least partially, by a cross-sectional surface of the at least one spindle tooth. The at least one spindle tooth can thus terminate in the axial recess wall. This allows for a particularly efficient transmission of an axial force between the shaft and an element arranged in the at least one recess.

[0019] The cut surface of the at least one spindle tooth is preferably spaced apart from the first wall end and / or the second wall end of the radial recess wall. The wall ends are preferably formed at the points where the radial recess wall exits the shaft along the recess arc shape. The arrangement of the cut surface is preferably determined in particular by the torque transmitted by the shaft. Along the radial recess wall, the torque transmission generally occurs primarily in the region of at least one of the wall ends. Depending in particular on the direction of rotation, the torque transmission can occur primarily in the region of the first wall end or the second wall end.

[0020] As previously described, the transmission of axial forces to or from the shaft generally occurs to a large extent via the cross-sectional area of ​​the at least one spindle tooth. By orienting the cross-sectional area of ​​the at least one spindle tooth relative to the first wall end and / or the second wall end, the mechanical stress on the shaft in the area of ​​the recess can be distributed as evenly as possible. In practice, three applications are particularly well-known, to which the shaft can be adapted by orienting the cross-sectional area of ​​the at least one spindle tooth relative to the wall ends.

[0021] In a first application, torque transmission, particularly during shaft rotation, can essentially only occur in a first direction of rotation, and thus primarily in the region of the first wall end. In this case, a shaft embodiment is preferably used in which the cutting surface of the at least one spindle tooth is spaced apart from the first wall end and located in the region of the second wall end.

[0022] In a second application, torque transmission, particularly during shaft rotation, can essentially only occur in a second direction of rotation, and thus primarily in the region of the second wall end. In this case, a shaft embodiment is preferably used in which the cutting surface of the at least one spindle tooth is spaced apart from the second wall end and located in the region of the first wall end.

[0023] In a third application, torque transmission, particularly during shaft rotation, can occur in both directions of rotation, primarily in the region of the first and second wall ends. In this case, a shaft embodiment is preferably used in which the cutting surface of the at least one spindle tooth is spaced apart from the first and second wall ends. The cutting surface of the at least one spindle tooth is preferably positioned centrally between the first and second wall ends.

[0024] In a preferred embodiment of the invention, the at least one recess comprises a plurality of recesses, and the at least one spindle tooth comprises a plurality of spindle teeth, wherein the number of recesses corresponds to the number of spindle teeth, and wherein the respective axial recess wall of each of the recesses is formed at least partially by the cross-sectional surface of one of the spindle teeth. This allows the transmission of torques and / or axial forces to be distributed uniformly around the circumference of the shaft. Particularly preferably, the shaft has four spindle teeth and four recesses, which are preferably distributed uniformly around the circumference of the shaft.

[0025] A rim is preferably arranged between the axial recess wall and the shaft end. After an element is placed in the at least one recess, the rim can be formed to secure the element axially. Preferably, the rim is annular, particularly circular. Its circumference is preferably free of interruptions. The shaft particularly preferably has a central bore along its longitudinal axis. The rim can thus be formed by an additional shoulder in the shaft's surface. An outer diameter of the rim is particularly preferred to be smaller than the maximum outer diameter of the shaft. This allows the shaft to be manufactured simply and cost-effectively from bar stock. Preferably, the shaft end is formed by a free end face of the rim. The rim can be intersected by the at least one recess.

[0026] A hub according to the invention comprises a longitudinal axis, a hub opening extending along the longitudinal axis, and an inner wall radially bounding the hub opening. The inner wall has at least one hub arc section with a hub arc radius such that the at least one hub arc section has a convex shape facing the longitudinal axis. This allows for a particularly uniform torque transmission to an element arranged in the hub opening. Due to the convex shape of the hub arc facing the longitudinal axis, the at least one hub arc section is preferably bulbous from the perspective of the longitudinal axis. The hub opening is preferably completely enclosed in a plane orthogonal to the longitudinal axis. The hub is preferably plate-shaped.

[0027] Preferably, the hub arc radius is constant. This makes it particularly easy to manufacture the hub arc radius, especially using a stamping process. Alternatively, the hub arc radius can be variable. In particular, the hub arc shape of at least one hub arc segment can correspond to at least one segment of a hypotrochoid. The hub arc shape can, in particular, correspond to the recess arc shape of the hub described above. This makes positioning the hub on the shaft particularly easy. Furthermore, the hub arc shape can, for example, comprise several straight lines that are angularly offset from each other and can be connected by an arc-shaped segment. The angular offset can be in the range between 90° and 180°.

[0028] According to the invention, the at least one hub arc section has a first hub arc end and a second hub arc end, each of which abuts a recess. This allows for a defined contact between the at least one hub arc section and an element arranged in the hub opening. The recesses can each be formed by a recess bore. The recess bores are preferably encompassed by the hub opening and can each be oriented concavely towards the longitudinal axis of the hub. The recess radius of each recess is preferably significantly smaller than the hub arc radius.

[0029] The at least one hub arc section can have a tangent-continuous transition at the first hub arc end to the relief groove adjacent to the first hub arc end and / or a tangent-continuous transition at the second hub arc end to the relief groove adjacent to the second hub arc end. A particularly large bearing surface can be achieved on an element arranged in the hub bore by means of the tangent-continuous transition. The tangent-continuous transition is preferably designed such that, at the transition of the respective hub arc end to the adjacent relief groove, the tangents applied to the hub arc section and to the relief groove have the same slope. In other words, the contour of the hub opening is preferably continuously differentiable at the transition of the at least one hub arc section to the corresponding relief groove.

[0030] When transmitting a torque acting around the hub's longitudinal axis to or from an element located in the hub opening, the highest loads can occur in the region of the first or second hub arc end, meaning that torque transmission primarily takes place in these areas. The tangent-continuous transition allows the load to be distributed over a relatively large area, thus minimizing stress on the hub. By selecting which of the hub arc ends has a tangent-continuous transition to the corresponding adjacent relief groove, the hub can be adapted to various applications. Corresponding to the applications previously described for the shaft, three main applications are known for the hub, to which the shaft can be adapted by adjusting the arrangement of the cut surface of the at least one spindle tooth relative to the wall ends.

[0031] In a first application, torque transmission can essentially only take place in one direction of rotation, and thus primarily in the region of the first hub arc end. In this case, a hub embodiment is preferably used in which the first hub arc end has a tangent-continuous transition to the relief groove adjacent to the first hub arc end.

[0032] In a second application, torque transmission can essentially only occur in a second direction of rotation, and thus primarily in the region of the second hub arc end. In this case, a hub embodiment is preferably used in which the second hub arc end has a tangent-continuous transition to the relief groove adjacent to the second hub arc end.

[0033] In a third application, torque transmission can occur in both directions of rotation, primarily in the area of ​​the first and second hub arc ends. In this case, a hub embodiment can be used in which the first hub arc end has a tangent-continuous transition to the relief groove adjacent to the first hub arc end, and in which the second hub arc end has a tangent-continuous transition to the relief groove adjacent to the second hub arc end.

[0034] Alternatively, the clearance radius can be chosen to be smaller and / or the clearances can be arranged further away from the hub's longitudinal axis in order to extend at least one hub arc section in the direction of the first hub arc end and in the direction of the second hub arc end, thus achieving a more even load distribution.

[0035] Preferably, the at least one hub arc section comprises a plurality of hub arc sections arranged uniformly around the hub's longitudinal axis in a circumferential direction around the hub opening. This allows the load on the hub, particularly during torque transmission, to be distributed uniformly around the hub's longitudinal axis. Preferably, the hub arc sections are of the same design. With three or more hub arc sections, the hub opening can thus have the shape of a polygon with undercuts at each of the corners. The hub most preferably has four hub arc sections.

[0036] A shaft-hub connection according to the invention comprises a shaft and a hub as described above. The hub is arranged on the shaft such that the at least one hub arc section is arranged in the at least one recess, the inner wall of the hub opening in the area of ​​the at least one hub arc section is arranged facing the radial recess wall of the at least one recess, and a first side surface of the hub is in operative connection with the axial recess wall of the at least one recess.

[0037] This allows at least one hub arc section to form an element arranged in at least one recess. Likewise, the shaft can form an element arranged in the hub opening.

[0038] Preferably, the hub is arranged on the shaft such that the hub's longitudinal axis is aligned with and positioned along the shaft's longitudinal axis. A functional connection can exist between the inner wall of the hub opening and the radial recess wall, in particular such that the inner wall and the radial recess wall bear against each other at least partially. This allows a force or torque to be transmitted between the inner wall and the radial recess wall.

[0039] The operative connection between the first side surface of the hub and the axial recess wall of the at least one recess serves to axially secure the hub on the shaft. Preferably, this operative connection is designed such that the first side surface rests directly against the axial recess wall.

[0040] In addition to the first side surface, the hub preferably has a second side surface, which is particularly preferably located opposite the first side surface. The side surfaces can each be formed by surfaces of the hub that adjoin the inner wall at their end faces. Due to this end-face arrangement, the first and second side surfaces are preferably oriented substantially orthogonally to the longitudinal axis of the hub. The edge between the inner wall and the first side surface can have a hub-side transition radius, which preferably corresponds to the shaft-side transition radius. This facilitates easier mounting of the hub onto the shaft.

[0041] The at least one hub arc section preferably corresponds in number and arrangement to the at least one recess. Preferably, the hub thus has the same number of hub arc sections as the shaft has recesses. By arranging the hub arc sections in a manner corresponding to the arrangement of the recesses, exactly one hub arc section can be arranged in each of the recesses. Particularly preferably, the shaft has four recesses and the hub has four hub arc sections.

[0042] In a preferred embodiment of the shaft-hub connection, the shaft has an interference fit with the hub in the region of the first hub arc end and in the region of the second hub arc end of the at least one recess, and the shaft has clearance in a central region of the at least one hub arc section located between the first and second hub arc ends. This allows for a backlash-free connection between the hub and the shaft, particularly at points where a significant portion of the torque transmission takes place, while simultaneously keeping the required assembly force low.

[0043] In an alternative embodiment, the shaft-hub connection can be designed such that the shaft has clearance relative to the hub in the area of ​​the first hub arc end and in the area of ​​the second hub arc end of the at least one recess, and that the shaft has an interference relative to the hub in a central area of ​​the at least one hub arc section arranged between the first hub arc end and the second hub arc end.

[0044] Preferably, the shaft-hub connection is designed such that the edge of the shaft is formed radially outwards and axially towards the hub, preferably crimped, and the second side surface of the hub, opposite the first side surface, is in operative contact with the formed edge. This allows the hub to be secured on the shaft in both axial directions. The operative connection between the second side surface and the formed edge is preferably designed such that the formed edge abuts the second side surface, particularly preferably directly.

[0045] A process for manufacturing a shaft-hub connection with a formed edge may include the following steps: Providing a previously described shaft having the previously described edge, providing a previously described hub, arranging the hub on the shaft such that ∘ or at least one hub arc section is arranged in the at least one recess, ∘ the inner wall of the hub opening in the area of ​​the at least one hub arc section is arranged facing the radial recess wall of the at least one recess, and ∘ a first side surface of the hub is in operative contact with the axial recess wall of the at least one recess, forming the edge projecting axially beyond the hub radially outwards and axially in the direction of the hub, in particular by flanging, in particular by a wobbling process or a rolling process, stopping the forming as soon as the edge rests against the second side surface.

[0046] By forming the edge projecting axially beyond the hub radially outwards and axially towards the hub, the air-filled space between the inner wall of the hub and the shaft can be at least partially filled with the shaft material. This improves the connection between the shaft and the hub. The forming process can be carried out quickly by using a wobble forming or a rolling forming process. Preferably, the forming process is stopped immediately after the edge contacts the second side surface, as continuing the forming process can reduce the strength of the formed edge.

[0047] An electric actuator according to the invention comprises a shaft-hub connection as described above. The electric actuator can, for example, be configured as an electric brake booster, particularly for a vehicle. Such brake boosters are used especially in electrically powered vehicles, such as electric cars.

[0048] An embodiment of the invention is explained with reference to the following figures. It shows: Figure 1a shows a first perspective view of a first embodiment of a wave, Figure 1b shows a second perspective view of the in Fig. 1 of the embodiment shown, Figure 2a a top view of a second embodiment of a shaft, Figure 2b first side view of the in Fig. 2a embodiment shown, Figure 2c a second side view of the in Fig. 2a The embodiment shown, Figure 3 a top view of a third embodiment of a shaft, Figure 4 a top view of a fourth embodiment of a shaft, Figure 5 a perspective view of a first embodiment of a hub, Figure 5 a top view of the in Fig. 5a The illustrated embodiment with the section plane AA shown in Figure 5c is shown in Fig. 5b Sectional view AA of the inscribed in Fig. 5a Figure 6 shows a top view of a second embodiment of a hub, Figure 7 shows a top view of a third embodiment of a hub, Figure 8 shows a first perspective view of an embodiment of a shaft-hub connection, and Figure 8 shows a second perspective view of the embodiment shown. Fig. 8a The exemplary embodiment shown, Figure 8, is a side view of the [description of the embodiment]. Fig. 8a The exemplary embodiment shown, Figure 8, is a top view of the [unclear text]. Fig. 8a The exemplary embodiment shown with section planes AA, BB and CC indicated, Figure 8 shows a section of the Fig. 8d Sectional view AA of the inscribed in Fig. 8a The exemplary embodiment shown with marked detail Y, Figure 8, fine enlarged view of the in Fig. 8e details shown Y, figure 8, a section of the in Fig. 8d section view BB of the inscribed Fig. 8a The exemplary embodiment shown, Figure 8, is a section of the Fig. 8d Sectional view CC of the inscribed in Fig. 8a The exemplary embodiment shown with marked detail Z, Figure 8, is an enlarged view of the [description of the embodiment shown]. Fig. 8h details shown Z.

[0049] The Figuren 1a bis 8i These figures show different views of various embodiments. The same reference numerals are used for identical and functionally equivalent parts. For clarity, not all reference numerals are used in every figure.

[0050] Fig. 1a Figure 1b shows a first embodiment of a shaft 10 for transmitting a torque and / or an axial force. The shaft 10 comprises a longitudinal shaft axis 12, a shaft surface 14, and a shaft end 16. The shaft surface 14 has four recesses 18. Each of the recesses 18 has an axial recess wall 20 and a radial recess wall 22 adjacent to the axial recess wall 20, the radial recess wall 22 having a first wall end 36 and a second wall end 38. While the axial recess wall 20 is particularly suitable for transmitting axial forces, the radial recess wall 22 is particularly intended for transmitting torques acting about the longitudinal shaft axis 12.

[0051] Each of the radial recess walls 22 is arranged parallel to the longitudinal axis 12 of the shaft. The axial recess walls 20 are arranged perpendicular to the corresponding radial recess wall 22. The radial recess walls 22 abut the corresponding axial recess walls 20 in such a way that a shaft-side transition radius 24 is arranged at the transition from each of the radial recess walls 22 to the corresponding axial recess wall 20, which can serve in particular to reduce notch stresses.

[0052] Each of the recesses 18 is axially open in the direction of the shaft end 16. The shaft 10 has no section extending axially from the direction of the shaft end 16 that would even partially obscure the recesses 18 (see in particular...). Fig. 1b Preferably, this can be used to create a Fig. 5a bis Fig. 7 The hub 48 shown is pushed onto the shaft 10 from the shaft end 16 until the hub 48 rests against the axial recess wall 20.

[0053] Each of the radial recess walls 22 has a recess radius 28 such that each of the radial recess walls 22 has a concave recess arc shape facing away from the longitudinal axis 12 of the shaft. Due to the concave recess arc shape facing away from the longitudinal axis 12 of the shaft, the recesses 18 are trough-shaped from the perspective of the shaft surface 14.

[0054] The recess radius 28 is designed to be variable such that the recess arc shape of the radial recess wall 22 extends from the first wall end 36 to the second wall end 38, and the recess radius 28 is variable. The recess radius 28 is designed to be variable such that the recess arc shape of the radial recess walls 22 corresponds to a segment of a hypotrochoid. The recess arc shapes of all recesses 18 of the shaft 10 correspond to segments of a single imaginary hypotrochoid. This applies to each of the illustrated embodiments. An imaginary hypotrochoid center point is located on the longitudinal axis 12 of the shaft. The recesses 18 can thus be distributed uniformly and symmetrically around the circumference of the shaft 10.The wave 10 is designed such that the corners of the hypotrochoid are arranged outside the wave-surface area 14 of the wave 10, so that the corners are not directly mapped onto the recess arc shape. However, the number of corners corresponds to the number of recesses 18 of the wave 10. In the in . Fig. 1a bis Fig. 7 The illustrated embodiments are therefore based on hypotrochoids with four corners.

[0055] In each of the Fig. 1a bis Fig. 7 In the illustrated embodiments, the shaft surface 14 has a spindle toothing with four spindle teeth 32. The spindle teeth 32 run helically around the shaft 10 along the longitudinal axis 12.

[0056] Especially the views in Fig. 1b Figure 2c illustrates that each of the axial recess walls 20 is formed at least partially by a cross-sectional surface 34 of one of the spindle teeth 32. Each of the spindle teeth thus terminates in one of the axial recess walls 20. The number of recesses 18 therefore corresponds to the number of spindle teeth 34.

[0057] The wall ends 36, 38 are preferably formed at the points where the respective radial recess wall 22 exits the shaft 10 along the recess arc shape. In the Fig. 1a bis 2c In the illustrated embodiments, the cut surface 34 of the respective spindle tooth 32 is spaced apart from the first wall end 36 and arranged in the region of the second wall end 38. The Fig. 1a bis 2c The embodiments shown are thus optimized for a first application case in which the torque transmission essentially only takes place in a first direction of rotation 40 and thus primarily in the area of ​​the first wall end 36.

[0058] The in Fig. 3 The illustrated embodiment of the shaft 10, however, is optimized for a second application in which the torque transmission takes place primarily in the region of the second wall end 38. This can be the case, for example, if torque transmission occurs primarily in a second direction of rotation 42. In this case, the cutting surfaces 34 of the spindle teeth 32 are spaced apart from the respective second wall end 38 and arranged in the region of the respective first wall end 36.

[0059] In a third use case, for which the in Fig. 4 In the illustrated embodiment of the shaft 10, torque transmission can take place in both directions of rotation, and thus primarily in the area of ​​the respective first wall end 36 and the respective second wall end 38. The cutting surfaces 34 of the spindle teeth are accordingly spaced apart from the respective first wall end 36 and the respective second wall end 38, and thus arranged centrally between the respective first wall end 36 and the respective second wall end 38.

[0060] The described arrangements of the cut surfaces 34 in the different embodiments allow the mechanical stress on the shaft 10 in the area of ​​the recesses 18 to be distributed as evenly as possible.

[0061] As especially in the Fig. 1a As can be clearly seen in Figure 2b, a rim 44 is arranged between the axial recess walls 20 and the shaft end 16. The shaft 10 has a central bore 46 along the longitudinal axis 12. The rim 44 is formed by an additional shoulder in the shaft surface 14, so that the rim 44 is annular and continuous. The shaft end 16 is formed by a free end face of the rim 44. The Fig. 2a bis Fig. 2c The embodiment shown differs from the one described in the Fig. 1a bis Fig. 1b The embodiment shown is characterized in that the edge 44 can be cut by the recesses 18.

[0062] The Fig. 5a bis 5c Figure 1 shows a first embodiment of a hub 48. The hub 48 comprises a longitudinal axis 50, a hub opening 52 extending along the longitudinal axis 50, and an inner wall 54 radially bounding the hub opening 52. The inner wall has four hub arc sections 56, each with a constant hub arc radius 58, such that each of the hub arc sections 56 has a convex shape facing the longitudinal axis 50. Due to the convex shape of the hub arc facing the longitudinal axis 50, each of the hub arc sections 56 is bulbous from the perspective of the longitudinal axis 50. The hub opening 52 is completely enclosed in a plane orthogonal to the longitudinal axis 50. The hub 48 is plate-shaped.

[0063] Each of the hub arc sections 56 has a first hub arc end 60 and a second hub arc end 62, each of the hub arc ends 60, 62 adjoining a relief groove 64, each of the relief grooves 64 being formed by a relief groove bore. The different hub bore ends 60, 62 of the hub arc sections 56, which are arranged successively in the circumferential direction around the hub longitudinal axis 50, each adjoin the same relief groove 64. The relief grooves 64 are each oriented concavely towards the hub longitudinal axis 12. The relief groove radius 65 of each of the relief grooves 64 is preferably significantly smaller than the respective hub arc radius 58.

[0064] The hub arch sections 56 of the in the Fig. 5a bis Fig. 7 The illustrated embodiments are arranged uniformly in a circumferential direction of the hub opening 52 around the hub's longitudinal axis 50 and are of identical design. This results in the shape of a quadrilateral with undercuts 65 at each of the corners.

[0065] As especially from Fig. 5b As can be seen, each of the hub arc sections 56 has a tangent-continuous transition 66 to the relief groove 64 adjacent to the respective first hub arc end 60 at the first hub arc end 60.

[0066] In accordance with the previously described applications for shaft 10, the hub 48 can be adapted to different applications by selecting which of the hub arc ends 60, 62 has a tangent-continuous transition 66 to the correspondingly adjacent undercut 64. The in Fig. 5a bis Fig. 5c The embodiment of the hub 48 shown is optimized for a first application case in which the torque transmission essentially only takes place in a first direction of rotation 40 and thus primarily in the area of ​​the first hub arc ends 60.

[0067] Fig. 6 Figure 1 shows an embodiment of the hub 48, which is intended for a second application in which the torque transmission essentially only takes place in a second direction of rotation 42 and thus primarily in the area of ​​the second hub arc ends 62. Each of the second hub arc ends 62 has a tangent-continuous transition 66 to the respective adjacent undercut 64.

[0068] The in Fig. 7 The illustrated embodiment of the hub 10 is designed for a third application in which torque transmission takes place in both directions of rotation 40, 42, and thus primarily in the region of the first hub arc ends 60 and the second hub arc ends 62. In this embodiment, the relief radius 65 is chosen to be smaller, and the relief grooves 64 are arranged further away from the hub longitudinal axis 50 than in the embodiments shown in the illustration. Fig. 5a bis Fig. 6 Examples of implementation shown.

[0069] The Fig. 8a bis 8i show a shaft-hub connection 68 comprising the in Fig. 2a bis 2b Wave 10 shown and the one in Fig. 5a bis 5c Hub 48 shown. As further information can be found in the Fig. 2a u. 2b as well as the Fig. 5a bis 5c As can be seen, the hub 48 has the same number of hub arc sections 56 as the shaft 10 has recesses 18. The hub 48 is arranged on the shaft 10 such that each of the hub arc sections 56 is located in exactly one of the recesses 18. As can be seen in particular from Fig. 8f As can be seen, the inner wall 54 of the hub opening 52 is arranged facing the radial recess wall 22 of the respective recess 18 in the area of ​​the hub arc sections 56. Furthermore, a first side surface 70 of the hub 48 is in operative contact with the axial recess walls 20 of the recesses 18, in that the first side surface 70 bears directly against the axial recess walls 20 (see in particular Fig. 8e ).

[0070] The hub 48 is arranged on the shaft 10 such that the hub longitudinal axis 50 is aligned along the shaft longitudinal axis 12 and is arranged on the shaft longitudinal axis 12.

[0071] The hub has, in addition to the first side surface 70, a side surface 70 opposite the first side surface 70 and in Fig. 8a The second side surface 72 is clearly visible. The side surfaces 70 and 72 abut the inner wall 54 of the hub 48 at their end faces and are oriented orthogonally to the hub's longitudinal axis 50. The edge between the inner wall 54 and the first side surface 70 has a hub-side transition radius 74 (see also Fig. 5a u. 5c), which corresponds to the wave-side transition radius 24.

[0072] The shaft 10 has an interference of 76 in the areas of the first hub arc ends 60 and in the areas of the second hub arc ends 62 relative to the hub 48, which can be seen from the overall view of the Fig. 8d, 8h u. 8i can be seen. In the central areas of the hub arc sections 56, a clearance 78 exists between the respective first hub arc ends 60 and the respective second hub arc ends 62. This is particularly evident when considering the Fig. 8d, 8e u. 8f. This allows a backlash-free connection between the hub 48 and the shaft 10 to be achieved, while at the same time keeping the required assembly force low.

[0073] How Fig. 8a As shown, the shaft-hub connection 68 is designed such that the edge 44 of the shaft 10 is formed radially outwards and axially in the direction of the hub 48, and the second side surface 72 of the hub is in operative connection with the formed edge 44 for axial securing of the hub 48 on the shaft 10. The formed edge 44 rests directly against the second side surface 72.

[0074] The shaft-hub connection 68 can be produced by first providing the shaft 10 and the hub 48 and then arranging the hub 48 on the shaft 10 as previously described. In this state, in which no deformation of the edge 44 has yet taken place, the shaft-hub connection is in the Fig. 8c bis 8i shown. Subsequently, the edge 44, which projects axially beyond the hub 48, can be formed radially outwards and axially towards the hub 48, in particular by crimping, for example by a wobbling process or a rolling process. As soon as the edge 44 abuts the second side surface 72, the forming is preferably stopped in order not to impair the strength of the formed edge 44. The state in which the edge abuts the second side surface 72 is shown in Fig. 8a shown. Reference symbol list

[0075] 10 Shaft 12 Shaft longitudinal axis 14 Shaft surface 16 Shaft end 18 Recess 20 Axial recess wall 22 Radial recess wall 24 Shaft-side transition radius 28 Recess radius 32 Spindle tooth 34 Cut surface 36 First wall end 38 Second wall end 40 First direction of rotation 42 Second direction of rotation 44 Edge 46 Central bore 48 Hub 50 Hub longitudinal axis 52 Hub opening 54 Inner wall 56 Hub arc section 58 Hub arc radius 60 First hub arc end 62 Second hub arc end 64 Undercut 65 Undercut radius 66 Tangential continuous transition 68 Shaft-hub connection 70 First side surface 72 Second side surface 74 Hub-side transition radius 76 Interference 78Game

Claims

1. Shaft (10), for transmitting a torque and / or an axial force, having a shaft longitudinal axis (12), a shaft lateral surface (14), and a shaft end (16), wherein the shaft lateral surface (14) has at least one recess (18) with an axial recess wall (20) and a radial recess wall (22) adjacent to the axial recess wall (20), wherein the radial recess wall (22) has a first wall end (36) and a second wall end (38), and wherein the at least one recess (18) is axially open in the direction of the shaft end (16), wherein the radial recess wall (22) has a recess radius (28), such that the radial recess wall (22) has, at least in sections, a concave recess arc shape facing away from the shaft longitudinal axis (12), characterized in that the shaft lateral surface (14) has a splined toothing with at least one spline tooth (32).

2. Shaft according to claim 1, characterized in that the recess arc shape of the radial recess wall (22) extends from the first wall end (36) to the second wall end (38) and / or the recess radius (28) is of variable design.

3. Shaft according to one of the preceding claims, characterized in that the recess arc shape of the radial recess wall (22) corresponds at least to a section of a hypotrochoid.

4. Shaft according to claim 3, characterized in that a hypotrochoid center of the hypotrochoid is arranged on the shaft longitudinal axis (12).

5. Shaft according to one of the preceding claims, characterized in that the axial recess wall (20) of at least one of the at least one recess (18) is formed, at least in sections, by a cut surface (34) of the at least one spline tooth (32).

6. Shaft according to claim 5, characterized in that the cut surface (34) of the at least one spline tooth (32) is arranged at a distance from the first wall end (36) and / or the second wall end (38) of the radial recess wall (22).

7. Shaft according to one of claims 5 to 6, characterized in that the at least one recess (18) comprises a plurality of recesses (18) and the at least one spline tooth (32) comprises a plurality of spline teeth (32), wherein the number of recesses (18) corresponds to the number of spline teeth (32), and wherein the respective axial recess wall (20) of each of the recesses (18) is formed, at least in sections, by the cut surface (34) of one of the spline teeth (32).

8. Shaft according to one of the preceding claims, characterized in that an edge (44) is arranged between the axial recess wall (20) and the shaft end (16).

9. Hub (48), having a hub longitudinal axis (50), a hub opening (52) extending along the hub longitudinal axis (50), and an inner wall (54) radially delimiting the hub opening (52), wherein the inner wall (54) has at least one hub arc section (56) with a hub arc radius (58), such that the at least one hub arc section (56) has a convex hub arc shape facing toward the hub longitudinal axis (50), characterized in that the at least one hub arc section (56) has a first hub arc end (60) and a second hub arc end (62), wherein each of the hub arc ends (60, 62) adjoins a respective undercut (64).

10. Hub according to claim 9, characterized in that the hub arc radius (58) is of constant design.

11. Hub according to one of claims 9 to 10, characterized in that the at least one hub arc section (56) has, at the first hub arc end (60), a tangentially continuous transition (66) to the undercut (64) adjacent to the first hub arc end (60) and / or, at the second hub arc end (62), a tangentially continuous transition (66) to the undercut (64) adjacent to the second hub arc end (62).

12. Hub according to one of claims 9 to 11, characterized in that the at least one hub arc section (56) comprises a plurality of hub arc sections (56), which are arranged uniformly in a circumferential direction of the hub opening (52) around the hub longitudinal axis (50).

13. Shaft-hub connection (68) having a shaft (10) according to one of claims 1 to 8 and a hub (48) according to one of claims 9 to 12, wherein the hub (48) is arranged on the shaft (10) such that • the at least one hub arc section (56) is arranged in the at least one recess (18), • the inner wall (54) of the hub opening (52), in the region of the at least one hub arc section (56), is arranged facing the radial recess wall (22) of the at least one recess (18), and • a first side surface (70) of the hub (48) is in operative connection with the axial recess wall (20) of the at least one recess (18).

14. Shaft-hub connection according to claim 13, characterized in that the at least one hub arc section (56) corresponds in number and arrangement to the at least one recess (18).

15. Shaft-hub connection according to one of claims 13 to 14, characterized in that the shaft (10), in the region of the first hub arc end (60) and in the region of the second hub arc end (62), has an interference (76) relative to the hub (48) in the at least one recess (18), and that the shaft (10), in a central region of the at least one hub arc section (56) arranged between the first hub arc end (60) and the second hub arc end (62), has a clearance (78) relative to the hub (48).

16. Shaft-hub connection according to one of claims 13 to 15 having a shaft according to claim 8, characterized in that the edge (44) of the shaft (10) is formed outward radially and axially in the direction of the hub (48), so that a second side surface (72) of the hub (48), arranged opposite the first side surface (70), is in operative connection with the formed edge (44).

17. Electric actuator having a shaft-hub connection (68) according to one of claims 13 to 16.