Shaft coupling and shaft for the shaft coupling

Abstract

Shaft coupling (1) for switching a first shaft (2) with a second shaft (3) arranged coaxially thereto, at least comprising the first shaft (2) which has on a circumferential surface (4) a plurality of first ball tracks (8) extending along an axis of rotation (5) over at least a first section (6) and a second section (7), which are spaced apart from each other along a circumferential direction (9) in the first section (6) by first webs (10) and in the second section (7) by second webs (11), as well as a plurality of first balls (12) arranged in the first section (6) and a plurality of second balls (13) arranged in the second section (7);wherein the first ball tracks (8) in the first section (6) are connected to each other via first openings (14) arranged in alignment along the circumferential direction (9) and in the second section (7) via second openings (15) arranged in alignment along the circumferential direction (9); wherein the shaft coupling (1) is switchable between at least two positions and the balls (12, 13) are displaceable between the positions within the respective section (6, 7) along the ball tracks (8); wherein the balls (12, 13) are arranged in the circumferential direction (9) in a coupled position aligned with the webs (10, 11) and in a decoupled position aligned with the openings (14, 15);wherein in the first section (6) a first end face (16) of the first webs (10) pointing towards the first openings (14) is smaller than in the second section (7) a second end face (17) pointing towards the second openings (15).;

Description

[0001] The invention relates to a shaft coupling for the switchable connection of a first shaft to a second shaft, which are arranged coaxially and have a common axis of rotation. The invention further relates to a shaft of the shaft coupling. The shafts can be connected to each other in a rotationally fixed manner (i.e., not rotatable relative to each other) via the shaft coupling for the transmission of torques (coupled position) or separated from each other (decoupled position). In the decoupled position, the shafts can rotate independently of each other, without any transmission of torques.

[0002] From DE 10 2019 129 818 A1, a shaft coupling for the switchable connection of a first shaft to a second shaft is known. The shafts have ball tracks which, together with ball tracks of a sleeve, form pairs of tracks. The balls are displaced by moving the sleeve along the axis of rotation. One of the shafts has openings between the ball tracks into which the balls can be moved. If the balls are arranged in the area of ​​the openings, the shafts can be rotated independently of each other. If the balls are arranged outside the openings, i.e., between the webs of the ball tracks, the shafts are coupled to each other.

[0003] In such shaft couplings, the individual ball tracks of a shaft are arranged at angular intervals along the circumference. These angular distances must be bridged to switch from the decoupled to the coupled position, i.e., to move the balls into the ball tracks or into the area between the webs. The relatively large angular distance necessitates a long switching time to establish the coupled position. Furthermore, switching is only possible within a very small angular range, determined by the (excessive) size of the ball track entrance opening relative to the balls. This also severely restricts the permissible difference in rotational speeds of the shafts to be coupled.

[0004] Increasing the size of the inlet opening or the width of the ball track is not possible, as this would worsen the NVH (noise, vibration, and harshness) performance of the shaft coupling (greater play of the balls in the ball tracks relative to the circumference). Reducing the angular spacing, for example by increasing the number of ball tracks, leads to a decrease in the transmissible torque. A smaller angular spacing on a larger effective diameter (ball tracks arranged on a larger diameter shaft) results in a larger installation space requirement, which is often not available.

[0005] A coupling with a shift sleeve is known from DE 37 01 898 A1.

[0006] From WO 2006 / 018096 A1 a longitudinal displacement unit intended for connecting two shafts is known.

[0007] From DE 10 2010 051 949 A1 a device for creating and releasing a rotationally fixed connection between two shafts is known.

[0008] From DE 10 2016 110 389 A1 a vibration decoupling arrangement is known by which two shafts can be connected to each other.

[0009] US 2018 / 0180144 A1 is directed at an actuator that controls the transmission of force between a cylinder and a shaft.

[0010] The object of the present invention is to at least partially solve the problems mentioned with reference to the prior art. In particular, a shaft coupling is to be proposed that can transmit high torques in a compact design. Specifically, short actuation strokes and low switching forces are to be achieved. Furthermore, switching of the shaft coupling should be possible even with significant differences in the rotational speeds of the shafts.

[0011] To solve these problems, a shaft coupling with the features according to claim 1 and a shaft with the features according to claim 11 contribute. Advantageous further developments are the subject of the dependent claims. The features listed individually in the claims can be combined with one another in a technologically meaningful way and can be supplemented by explanatory details from the description and / or details from the figures, thereby showing further embodiments of the invention.

[0012] A shaft coupling is proposed for the switchable connection of a first shaft to a second shaft. The shafts are arranged coaxially and have a common axis of rotation.

[0013] The shaft coupling comprises at least the first shaft and a plurality of first balls and second balls. The first shaft has, on a circumferential surface, a plurality of first ball tracks extending along an axis of rotation over at least a first section and a second section. The first ball tracks are spaced apart along a circumferential direction in the first section by first webs and in the second section by second webs. The plurality of first balls are arranged in the first section (in every position of the shaft coupling). The plurality of second balls are arranged in the second section (in every position of the shaft coupling).The first ball tracks are connected in the first section by first openings arranged in alignment with each other along the circumferential direction, and in the second section by second openings arranged in alignment with each other along the circumferential direction.

[0014] The shaft coupling can be switched between at least (or exclusively) two positions. The balls can be displaced between the positions within the respective section along the ball tracks. In a coupled position, the balls are aligned with the webs in the circumferential direction, and in a decoupled position, they are aligned with the openings. In the first section, the first end face of the first webs, facing the first openings, is smaller than the second end face of the second opening in the second section.

[0015] The proposed shaft coupling enables the transmission of high torques in a compact design. Torques can be transmitted via a large number of balls.

[0016] The ball tracks extend, in particular, parallel to the axis of rotation and preferably perpendicular to a circumferential direction. The ball tracks have a track base flanked on both sides by track side walls formed by the webs. The track base extends, in particular, at a constant distance from the axis of rotation and preferably parallel to the axis of rotation. The track base is arranged either on the smallest or the largest diameter of the ball track. The track side walls support the balls against the circumferential direction. The web with its end face is arranged between the track side walls of adjacent ball tracks.

[0017] In particular, each first ball track contains several balls, preferably two or more than two balls.

[0018] In operation, the first set of balls is permanently located in the first section, and the second set of balls is permanently located in the second section. When the shaft coupling is engaged, the balls are displaced within their respective sections along the axis of rotation. Therefore, when the balls are in the disengaged position of the shaft coupling, they can move circumferentially relative to the first shaft. The first shaft can thus be freely rotated relative to the balls. To engage the shaft coupling, the balls enter the ball track of the respective section. In the engaged position, the balls are aligned circumferentially with the webs, preventing rotation of the first shaft relative to the balls.

[0019] As a result of the smaller size of the first end face compared to the second end faces, the entry of the first balls into the first ball tracks can be facilitated. In particular, the angular distance between two first ball tracks is thereby reduced, while at least in the area of ​​the first end face, the play between the first balls and the ribs of the first ball track relative to the circumferential direction is increased.

[0020] This allows for greater differences in the rotational speeds of the shafts being coupled. Furthermore, the reduced angular distance shortens the switching time required to establish the coupled position.

[0021] The first end face of the first webs is reduced in size, in particular, to enlarge the entrance opening of the first ball track. Specifically, the entrance opening of the first ball track is enlarged in the circumferential direction. Compared to the second entrance opening of the first ball track in the second section, the first entrance opening is enlarged by at least 2%, preferably by at least 4%, and most preferably by at least 8%.

[0022] In particular, a chamfer adjoins the first end face of the first web. This chamfer is inclined towards one of the first ball tracks located adjacent to the first web. The chamfer forms a first entry opening for the first ball track, enlarged in the circumferential direction. As a result of the chamfer, the width of the first ball track tapers progressively from the first entry opening along the axis of rotation. The circumferential width of the first ball track is therefore at its maximum at the position along the axis of rotation where the first end face is located, and tapers progressively from there to the (then constant) minimum width of the first ball track.

[0023] In particular, a chamfer is arranged on each first end face. This chamfer is specifically arranged on the same web side walls of the first webs.

[0024] The minimum width of the first ball track in the first section is, in particular, equal to the (minimal) width of the first ball track in the second section. The first ball track in the second section, in particular, has a constant width.

[0025] The chamfer includes, in particular, a recess of the edge that forms the transition between the end face and the track side wall of the web. The end face present at a position along the axis of rotation defines, in particular, the size or width of the entry opening of the first ball track.

[0026] In particular, two chamfers adjoin the first end face of each first web. Each chamfer is inclined towards one of the other first ball tracks located adjacent to the first web. The chamfers form the first entry opening of the first ball tracks, enlarged in the circumferential direction. As a result of the chamfers, the width of the first ball tracks tapers progressively from the first entry opening along the axis of rotation.

[0027] In particular, two chamfers are arranged on each first end face.

[0028] In particular, the first end face (i.e., the area of ​​the first end face) is at most 95%, preferably at most 85%, most preferably at most 75% of the second end face (i.e., the area of ​​the second end face).

[0029] In particular, the first spheres are arranged in the decoupled position along the axis of rotation at a first distance from the first end faces, and the second spheres are arranged at a second distance from the second end faces. Specifically, the first distance is less than the second distance.

[0030] The difference between the first and second distances is specifically designed so that the first balls initially enter the first ball tracks from the first openings (and via the enlarged first entry openings) along the axis of rotation. As the width narrows progressively from the first entry opening, the first balls become increasingly aligned with the first ball tracks as they move along the axis of rotation. Specifically, the second distance is designed such that the second balls only enter the first ball tracks in the second section from the second openings once the first balls in the first section have reached their minimum width.

[0031] This facilitates the threading of the first balls in the first section. By threading only the first balls into the first ball tracks and by progressively improving the alignment of these first balls with the first shaft via the chamfers, the second balls can be aligned with the first ball tracks in the second section. This reduces switching times and simplifies the switching process. The transmission of torque is not affected.

[0032] In particular, the shaft coupling additionally comprises at least the second shaft with a plurality of second ball tracks extending along the axis of rotation, as well as a sleeve with third ball tracks that at least partially covers the first and second ball tracks along the axis of rotation. Furthermore, the shaft coupling additionally comprises third balls. The first and second balls are arranged in first pairs of tracks formed by the first ball tracks and the third ball tracks, and the third balls are arranged in second pairs of tracks formed by the second ball tracks and the third ball tracks. The balls can be moved between positions along the ball tracks by shifting the sleeve along the axis of rotation, so that in the coupled position the shafts are rotationally fixed to one another, and in the decoupled position the first shaft and the second shaft can be rotated relative to each other.

[0033] The balls are moved along the shafts primarily by a rolling motion (and not by a sliding motion). As a result of the balls' rolling motion, the shaft coupling can be actuated with minimal force.

[0034] In particular, the shafts are arranged side by side along the axis of rotation, and the sleeve extends radially outwards over the first and second ball tracks. The third ball tracks form outer (i.e., arranged radially outwards) ball tracks, and together with the inner (i.e., arranged radially inwards) first ball tracks, they form the first pairs of tracks, and together with the inner second ball tracks, they form the second pairs of tracks.

[0035] Alternatively, the first and second ball tracks overlap each other along the axis of rotation, and the sleeve is arranged radially between the first and second ball tracks. One shaft has inner (radially inward) ball tracks, and the other shaft has outer (radially outward) ball tracks. The sleeve has inner third ball tracks and outer third ball tracks.

[0036] In particular, the first shaft has a plurality of second sections arranged one after the other along the axis of rotation.

[0037] In particular, a cage is arranged between the sleeve and each shaft, wherein the (first and second) balls are arranged at fixed distances to each other via the cage, at least with respect to an axial direction extending along the axis of rotation.

[0038] The distances between the balls arranged in the second ball tracks can be designed differently than the distances between the balls arranged in the first ball tracks (but can also be identical).

[0039] In particular, the (respective) cage is not connected to the sleeve, but is displaced along the axial direction via the balls. Since the balls are always arranged in the third ball tracks, the cage rotates together with the sleeve. By displacing the sleeve, the balls, and consequently the cage, can be displaced along the axial direction, especially (exclusively) during a rolling motion. This allows the balls to be displaced within the sections, enabling either a decoupled or coupled position of the shaft coupling.

[0040] Specifically, only the first few ball tracks are connected along the circumference via openings. These first tracks are connected in a first section via openings and in a second section via openings along the circumference. This allows the first and second balls to be moved along the circumference on a diameter corresponding to the base of the first track. The openings in the first section and the openings in the second section are aligned with each other, particularly along the circumference. Thus, the openings in each section form a ball track running exclusively in the circumference.

[0041] By shifting the sleeve along the axis of rotation, the first and second balls can be displaced along the (first, second, and third) ball tracks, allowing them to be positioned in the respective openings. This enables the balls to be displaced along the circumferential ball track formed by the openings, allowing them to be moved relative to the first shaft along its circumference. This, in turn, allows the sleeve and the second shaft to be rotated relative to the first shaft. Specifically, all balls arranged on the first shaft must be positioned in such sections with openings so that the sleeve, with the balls in the first ball tracks, can be rotated relative to the first shaft.

[0042] The shafts are connected to each other in a rotationally fixed manner if the balls arranged in the first ball tracks are aligned outside the openings and along the circumferential direction with the webs.

[0043] In particular, at least one of the track pairs contains a plurality of rows of balls, wherein the balls of a row are arranged adjacent to each other at a position along the axis of rotation and in the circumferential direction. Specifically, the number of rows on the first shaft corresponds to the number of (first and second) sections provided on the first shaft.

[0044] In particular, the sleeve can be displaced relative to the shafts along an axial direction extending along the axis of rotation by means of an actuating device.

[0045] Various actuation devices can be used. Due to the low friction between balls and ball tracks (because of rolling friction, which is lower than sliding friction), only small actuation forces are required to switch the shaft coupling.

[0046] A (first) shaft for the described shaft coupling is further proposed. The shaft has a plurality of first ball tracks on a circumferential surface, extending along an axis of rotation over at least a first section and a second section. The first ball tracks are spaced apart along a circumferential direction by first webs in the first section and by second webs in the second section. In the first section, the first ball tracks are connected along the circumferential direction by first openings aligned with each other, and in the second section by second openings aligned with each other. In the first section, the first end face of the first webs, facing the first openings, is smaller than the second end face of the second opening in the second section.

[0047] The statements regarding the shaft coupling and, in particular, the first shaft described in connection with it, are especially applicable to the shaft and vice versa.

[0048] Reference is made in particular to the shaft coupling according to DE 10 2019 129 818 A1. The explanations given therein regarding the arrangement of the first shaft, the second shaft, the sleeve and the cage (or cages) are particularly applicable to the shaft arrangement described here.

[0049] The use of indefinite articles (“a”, “an”, “one”, and “ones”), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Accordingly, terms or components introduced by these articles are to be understood as occurring at least once and, in particular, may also occur multiple times.

[0050] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0051] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a shaft coupling in a side view, partially in section; Fig. 2: a shaft coupling in a side view, partially in section, in a separated state; Fig. 3: the shaft coupling according Fig. 2 in a side view; Fig. 4: a first design variant of a first shaft in a view along the axis of rotation; Fig. 5: a second variant of a first shaft in a view along the axis of rotation; Fig. 6: a third variant of a first shaft in a view along the axis of rotation; Fig. 7: a detail of a known shaft coupling in a decoupled position, in a view along a radial direction; Fig. 8: the detail after Fig. 7, with the shaft coupling in a coupled position, in a view along a radial direction; and Fig. 9: A detail of a shaft coupling in a decoupled position, in a view along a radial direction.

[0052] The Fig. Figure 1 shows a shaft coupling 1 in a side view, partially in section. The shaft coupling 1 serves to connect a first shaft 2 to a second shaft 3 in a switchable manner. The shafts are arranged coaxially to each other and have a common axis of rotation 5.

[0053] The shaft coupling 1 comprises the first shaft 2 and a plurality of first balls 12 and second balls 13. The first shaft 2 has on a circumferential surface 4 a plurality of first ball tracks 8 extending along an axis of rotation 5 over at least a first section 6 and a second section 7. The first ball tracks 8 are spaced apart from one another along a circumferential direction 9 in the first section 6 by first webs 10 and in the second section 7 by second webs 11. The plurality of first balls 12 are arranged (in every position of the shaft coupling 1) in the first section 6. The plurality of second balls 13 are arranged (in every position of the shaft coupling 1) in the second section 7. The first ball tracks 12 are connected in the first section 6 by first openings 14 (not shown here, see [reference]) which are aligned with one another along the circumferential direction 9. Fig. 9) and in the second section 7 are connected to each other via second openings 15 arranged in alignment along the circumferential direction 9.

[0054] The shaft coupling 1 can only be switched between two positions. The balls 12, 13 can be displaced between the positions within the respective sections 6, 7 along the ball tracks 8, 23. In the circumferential direction 9, the balls 12, 13 are aligned with the webs 10, 11 (shown here) in a coupled position and with the openings 14, 15 in a decoupled position (indicated here). In the first section 6, a first end face 16 of the first webs 10 points towards the first openings 14 (see Fig. 9) smaller than in the second section 7 is a second end face 17 pointing towards the second openings 15.

[0055] The shaft coupling 1 additionally comprises the second shaft 3 with a plurality of second ball tracks 23 extending along the axis of rotation 5, as well as a sleeve 24 with third ball tracks 25, which at least partially covers the first ball tracks 8 and the second ball tracks 23 along the axis of rotation 5. The shaft coupling 1 further comprises third balls 26. The first and second balls 12, 13 are arranged in first track pairs 27 formed by the first ball tracks 8 and the third ball tracks 25, and the third balls 26 are arranged in second track pairs 28 formed by the second ball tracks 23 and the third ball tracks 25. The balls 12, 13, 26 can be displaced between the positions along the ball tracks 8, 23, 25 by moving the sleeve 24 along the axis of rotation 5, so that in the coupled position the shafts 2, 3 are connected to each other in a rotationally fixed manner and in the decoupled position the shafts 2, 3 can be rotated against each other.

[0056] The shafts 2, 3 are arranged side by side along the axis of rotation 5, and the sleeve 24 extends in a radial direction 30 outwards over the first and second ball tracks 8, 23. The third ball tracks 26 form outer ball tracks (i.e., arranged on the outside in the radial direction 30) and together with the inner (i.e., arranged on the inside in the radial direction 30) first ball tracks 8 form the first pairs of tracks 27, and together with the inner second ball tracks 23 form the second pairs of tracks 28.

[0057] The first wave 2 has a plurality of second sections 7 which are arranged adjoining each other along the axis of rotation 5.

[0058] A cage 31 is arranged between the sleeve 24 and each shaft 2, 3, wherein the (first and second) balls 12, 13 are arranged at fixed distances 33 to each other over the cage 31 opposite an axial direction 32 extending along the axis of rotation 5.

[0059] In the operation of the shaft coupling 1, the first balls 12 are permanently arranged in the first section 6 and the second balls 13 are permanently arranged in the second section 7. When the shaft coupling 1 is engaged, the balls 12, 13 are displaced within their respective sections 6, 7 along the axis of rotation 5. Thus, when the balls 12, 13 are in a decoupled position of the shaft coupling 1 in their respective openings 14, 15, they can move relative to the first shaft 2 along the circumferential direction 9. The first shaft 2 can therefore be freely rotated relative to the balls 12, 13. To engage the shaft coupling 1, the balls 12, 13 enter the first ball track 8 of the respective section 6, 7. In the coupled position, the balls 12, 13 are arranged in the circumferential direction 9 aligned with the webs 10, 11, so that a rotation of the first shaft 2 relative to the balls 12, 13 is not possible.

[0060] The balls 12, 13, 26 are assigned either to the first ball tracks 8 or to the second ball tracks 23. Each ball 12, 13, 26 is therefore only arranged in either a first ball track 8 or in a second ball track 23, whereby even when the shaft coupling 1 is switched, no ball 12, 13, 26 is moved from the first shaft 2 to the second shaft 3 and vice versa.

[0061] The sleeve 24 can be displaced relative to the shafts 2, 3 along an axial direction 32 extending along the axis of rotation 5 by means of an actuating device 34. The sleeve 24 can be displaced against the action of a spring element 35, so that the sleeve 24 can be automatically returned to its original position. The first spring element 35 is implemented by a compression spring. Via the actuating device 34, the sleeve 24 can be displaced in the direction 29 from a starting position (see the position of the sleeve 24 shown with dashed lines in the figure). Fig. 1) are displaced against the spring force to engage the shaft coupling 1, whereby the sleeve 24 can be returned to its initial position solely by the spring force.

[0062] Fig. Figure 2 shows a shaft coupling 1 in a side view, partially in section, in a separated state. Fig. Figure 3 shows the shaft coupling 1 after Fig. 2 in a side view. The Fig. 2 and Fig. The three will be described together below. The explanations regarding... Fig. 1 is referenced.

[0063] The shafts 2 and 3 are arranged coaxially and have a common axis of rotation 5. The shaft coupling 1 comprises the first shaft 2 and a plurality of first balls 12 and second balls 13. The first shaft 2 has, on a circumferential surface 4, a plurality of first ball tracks 8 extending along an axis of rotation 5 over at least a first section 6 and a second section 7. The shaft coupling 1 further comprises the second shaft 3 with a plurality of second ball tracks 23 extending along the axis of rotation 5, as well as a sleeve 24 with third ball tracks 25 that at least partially covers the first ball tracks 8 and the second ball tracks 23 along the axis of rotation 5. The shaft coupling 1 further comprises third balls 26.

[0064] Unlike Fig. In each of the track pairs 27, 28, two rows of balls 12, 13, 26 are arranged. The balls 12, 13 are arranged in the two sections 6, 7 of the first ball tracks 8 and the first shaft 2, respectively. The first ball tracks 8 are connected to each other along a circumferential direction 9 in a first section 6 via first openings 14 and in a second section 7 via second openings 15. The sections 6, 7 are arranged side by side along the axial direction 32. If the balls 12, 13 are thus arranged in alignment with the webs 10, 11, torques can be transmitted between the sleeve 24 and the first shaft 2 via the balls 12, 13. If the balls 12, 13 are arranged in alignment with the openings 14, 15, the balls 12, 13 together with the second shaft 3 and the sleeve 24 and the cage 31 can be freely rotated relative to the first shaft 2 or displaced along the circumferential direction 9.

[0065] A cage 31 is arranged between sleeve 24 and shafts 2, 3, wherein the balls 12, 13, 26 are arranged at fixed distances 33 to each other over the cage 31 opposite an axial direction 32 extending along the axis of rotation 5.

[0066] The cage 31 is not connected to the sleeve 24, but is displaced along the axial direction 32 by the balls 12, 13, 26 which move through the sleeve 24. The sleeve 24 has stops 36 against which the cage 31 is supported relative to the axial direction 32. The cage 31 can be aligned with the sleeve 24 along the axial direction 32 by means of the stops 36.

[0067] Since the balls 12, 13, 26 are always arranged in the third ball tracks 25, the cage 31 rotates together with the sleeve 24. By displacing 29 the sleeve 24, the cage 31 and, via the cage 31, the balls 12, 13, 26 can be displaced along the axial direction 32. This allows the balls 12, 13 to be displaced in sections 6, 7, so that a decoupled position of the shaft coupling 1 is achieved (see Fig. 2).

[0068] Fig. Figure 4 shows a first embodiment of a first shaft 2 in a view along the axis of rotation 5. Fig. Figure 5 shows a second embodiment of a first shaft 2 in a view along the axis of rotation 5. Fig. Figure 6 shows a third embodiment of a first shaft 2 in a view along the axis of rotation 5. See the explanations regarding the Fig. Reference is made to 1 to 3. Fig. Items 4 to 6 are described together below.

[0069] In shaft couplings 1, the individual first ball tracks 8 of a first shaft 2 are arranged at an angular distance 37 from each other along the circumferential direction 9 (see Fig. 4) These angular distances 37 must therefore be bridged to switch from the decoupled position to the coupled position, so that the balls 12, 13 can be moved into the first ball tracks 8 or into the area between the webs 10, 11. The relatively large angular distance 37 necessitates a long switching time to establish the coupled position. Switching is only possible within a very small angular range 38, which is determined by the (excessive) size of the first entry opening 19 of the first ball tracks 8 compared to the balls 12, 13. Furthermore, this severely restricts the permissible difference in the rotational speeds of the shafts 2, 3 to be coupled.

[0070] However, increasing the size of the first entry opening 19 or the width 20 of the first ball track 8 is not possible, as this would worsen the NVH (noise, vibration, and harshness) behavior of the shaft coupling 1 (greater play of the balls 12, 13 in the first ball tracks 8 relative to the circumferential direction 9). A reduction of the angular distance 37, e.g., by increasing the number of first ball tracks 8 (see Fig. 5) leads to a reduction in the transmissible torque. A smaller angular distance 37 on a larger effective diameter 39 (first ball tracks 8 are arranged on a larger diameter of the first shaft 2, see Fig. 6) leads to an increased need for building space, which often cannot be provided.

[0071] Fig. Figure 7 shows a detail of a known shaft coupling 1 in a decoupled position, in a view along a radial direction 30. Fig. 8 shows the detail after Fig. 7, with the shaft coupling 1 in a coupled position, in a view along a radial direction 30. The Fig. 7 and Fig. 8 are described together below.

[0072] The shaft coupling 1 comprises the first shaft 2 and a plurality of first balls 12 and second balls 13. The first shaft 2 has on a circumferential surface 4 a plurality of first ball tracks 8 extending along an axis of rotation 5 over at least a first section 6 and a second section 7. The shaft coupling 1 additionally comprises the second shaft 3 with a plurality of second ball tracks 23 extending along the axis of rotation 5, in which third balls 26 are arranged.

[0073] The first ball tracks 8 are spaced apart from one another along a circumferential direction 9 in the first section 6 by first webs 10 and in the second section 7 by second webs 11. The majority of first balls 12 are arranged in the first section 6 (in every position of the shaft coupling 1). The majority of second balls 13 are arranged in the second section 7 (in every position of the shaft coupling 1). The first ball tracks 8 are connected to each other in the first section 6 by first openings 14 aligned with each other along the circumferential direction 9 and in the second section 7 by second openings 15 aligned with each other along the circumferential direction 9.

[0074] The shaft coupling 1 can only be switched between two positions. The balls 12, 13 can be displaced between the positions within the respective sections 6, 7 along the ball tracks 8, 23. In a coupled position, the balls 12, 13 are aligned in the circumferential direction 9 with the webs 10, 11 ( Fig. 8) and in a decoupled position ( Fig. 7) arranged flush with the openings 14, 15. The first end face 16 of the first webs 10, pointing towards the first openings 14, is designed in the same way as a second end face 17 pointing towards the second openings 15 in the second section 7.

[0075] The first balls 12 are arranged in the decoupled position along the axis of rotation 5 at a first distance 21 to the first end faces 16 and the second balls 13 at an equal second distance 22 to the second end faces 17.

[0076] When 29 of the balls 12, 13 are moved along the first ball track 8, the balls 12, 13 simultaneously enter the areas of the first ball tracks 8 that are limited by the bridges 10, 11 opposite the circumferential direction 9.

[0077] Fig. Figure 9 shows a detail of a shaft coupling 1 in a decoupled position, in a view along a radial direction 30. See the explanations regarding the Fig. Reference is made to numbers 1 to 8.

[0078] The shaft coupling 1 comprises the first shaft 2 and a plurality of first balls 12 and second balls 13. The first shaft 2 has on a circumferential surface 4 a plurality of first ball tracks 8 extending along an axis of rotation 5 over at least a first section 6 and a second section 7. The shaft coupling 1 additionally comprises the second shaft 3 with a plurality of second ball tracks 23 extending along the axis of rotation 5, in which third balls 26 are arranged.

[0079] The balls 12, 13 are displaceable between the positions within the respective sections 6, 7 along the first ball tracks 8. In the circumferential direction 9, the balls 12, 13 are aligned with the openings 14, 15 in the decoupled position shown. In the first section 6, the first end face 16 of the first webs 10, pointing towards the first openings 14, is smaller than the second end face 17, pointing towards the second openings 15, in the second section 7.

[0080] As a result of the reduction in size of the first end face 16 compared to the second end faces 17, the entry of the first balls 12 into the first ball tracks 8 (or into the area between the first ribs 10) can be facilitated. The angular distance 37 (indicated here) between two first ball tracks 8 is thus effectively reduced, and, at least in the area of ​​the first end face 16, the clearance between the first balls 12 and the first ribs 10 of the first ball track 8 relative to the circumferential direction 9 is increased.

[0081] The first end face 16 of the first webs 10 is reduced in size so that a first entry opening 19 of the first ball track 8 is enlarged. The first entry opening 19 of the first ball track 8 is thereby enlarged in the circumferential direction 9.

[0082] A chamfer 18 adjoins the first end face 16 of the first web 10. The chamfer 18 is inclined towards one of the first ball tracks 8 arranged adjacent to the first web 10. The chamfer 18 forms a first entry opening 19 of the first ball track 8, enlarged in the circumferential direction 9. As a result of the chamfer 18, a width 20 of the first ball track 8 tapers progressively from the first entry opening 19 along the axis of rotation 5. The width 20 of the first ball track 8, extending in the circumferential direction 9, is therefore at its maximum at the position along the axis of rotation 5 where the first end face 16 is located, and tapers progressively from there to the (then constant) minimum width 20 of the first ball track 8.

[0083] The minimum distance 20 of the first ball track 8 in the first section 6 is equal to the minimum and constant distance 20 of the first ball track 8 in the second section 7.

[0084] The chamfer 18 includes a recess of the edge that forms the transition between the first end face 16 and the track side wall of the first web 10.

[0085] The first spheres 12 are arranged in the decoupled position along the axis of rotation 5 at a first distance 21 from the first end faces 16, and the second spheres 13 at a second distance 22 from the second end faces 17. The second distance 22 is greater than the first distance 21.

[0086] The difference between the first distance 21 and the second distance 22 is dimensioned such that the first balls 12 initially emerge from the first openings 14 along the axis of rotation 5 and enter the first ball tracks 8 via the enlarged first entry openings 19. As a result of the increasing narrowing of the width 20 starting from the first entry opening 19, the first balls 12 are increasingly aligned with the first ball tracks 8 as they progressively shift 29 along the axis of rotation 5. The second distance 22 is designed such that the second balls 13 only enter the first ball tracks 8 in the second section 7 from the second openings 15 when the first balls 12 in the first section 6 have reached the minimum width 20.

[0087] This facilitates the threading of the first balls 12 via the first section 6. By threading only the first balls 12 into the first ball tracks 8 and by successively aligning the first balls 12 with the first shaft 2 via the chamfers 18, the second balls 13 can be aligned with the first ball tracks 8 in the second section 7. This reduces switching times and simplifies the switching process. The transmission of torque is not affected. Reference symbol list 1 shaft coupling 2 first wave 3 second wave 4 Circumferential area 5 axis of rotation 6 first section 7 second section 8 first marble run 9 Circumferential direction 10 first jetty 11 second jetty 12 first ball 13 second ball 14 first breakthrough 15 second breakthrough 16 first front face 17 second front face 18th phase 19 first entry opening 20 width 21 first gap 22 second gap 23 second marble run 24 sleeve 25 third marble run 26 third ball 27 first pair of lanes 28 second pair of lanes 29 Relocation 30 radial direction 31 cage 32 axial direction 33 Distance 34 Actuating device 35 Spring element 36 stops 37 angular distance 38 angle range 39 Effective diameter

Claims

Shaft coupling (1) for switching a first shaft (2) with a second shaft (3) arranged coaxially thereto, at least comprising the first shaft (2) which has on a circumferential surface (4) a plurality of first ball tracks (8) extending along an axis of rotation (5) over at least a first section (6) and a second section (7), which are spaced apart from each other along a circumferential direction (9) in the first section (6) by first webs (10) and in the second section (7) by second webs (11), as well as a plurality of first balls (12) arranged in the first section (6) and a plurality of second balls (13) arranged in the second section (7);wherein the first ball tracks (8) in the first section (6) are connected to each other via first openings (14) arranged in alignment along the circumferential direction (9) and in the second section (7) via second openings (15) arranged in alignment along the circumferential direction (9); wherein the shaft coupling (1) is switchable between at least two positions and the balls (12, 13) are displaceable between the positions within the respective section (6, 7) along the ball tracks (8); wherein the balls (12, 13) are arranged in the circumferential direction (9) in a coupled position aligned with the webs (10, 11) and in a decoupled position aligned with the openings (14, 15);wherein in the first section (6) a first end face (16) of the first webs (10) pointing towards the first openings (14) is smaller than in the second section (7) a second end face (17) pointing towards the second openings (15).; Shaft coupling (1) according to claim 1, wherein a chamfer (18) adjoins the first end face (16) at least towards one of the first ball tracks (8) arranged adjacent to the first web (10), through which a first entry opening (19) of the first ball track (8) is formed which is enlarged in the circumferential direction (9); wherein the chamfer (18) causes a width (20) of the first ball track (8) to taper progressively from the first entry opening (19) and along the axis of rotation (5). Shaft coupling (1) according to one of the preceding claims, wherein a chamfer (18) adjoins the first end face (16) towards both of the first ball tracks (8) arranged adjacent to the first web (10), through which a first entry opening (19) of the first ball tracks (8) is formed which is enlarged in the circumferential direction (9); wherein the chamfers (18) cause a width (20) of the first ball tracks (8) to taper progressively from the first entry opening (19) and along the axis of rotation (5). Shaft coupling (1) according to one of the preceding claims, wherein the first end face (16) is at most 95% of the second end face (17). Shaft coupling (1) according to one of the preceding claims, wherein the first balls (12) are arranged in the decoupled position along the axis of rotation (5) at a first distance (21) to the first end faces (16) and the second balls (13) at a second distance (22) to the second end faces (17), wherein the first distance (21) is less than the second distance (22). Shaft coupling (1) according to one of the preceding claims, at least comprising the second shaft (3) with a plurality of second ball tracks (23) extending along the axis of rotation (5) and a sleeve (24) at least partially covering the first ball tracks (8) and the second ball tracks (23) along the axis of rotation (5) with third ball tracks (25) and third balls (26); wherein the first and second balls (12, 13) are arranged in first track pairs (27) formed by the first ball tracks (8) with the third ball tracks (25) and the third balls (26) are arranged in second track pairs (28) formed by the second ball tracks (23) with the third ball tracks (25);wherein by a displacement (29) of the sleeve (24) along the axis of rotation (5) the balls (12, 13, 26) can be displaced between the positions along the ball tracks (8, 23, 25), so that in the coupled position the shafts (2, 3) are rotationally fixed to each other and in the decoupled position can be rotated relative to each other.; Shaft coupling (1) according to claim 6, wherein the shafts (2, 3) are arranged side by side along the axis of rotation (5) and the sleeve (24) extends in a radial direction (30) outside over the first ball tracks (8) and the second ball tracks (23), wherein the third ball tracks (25) form outer ball tracks and together with the inner first ball tracks (8) form the first track pairs (27) and together with the inner second ball tracks (23) form the second track pairs (28). Shaft coupling (1) according to claim 6, wherein first ball tracks (8) and second ball tracks (23) overlap each other along the axis of rotation (5) and the sleeve (24) is arranged along a radial direction (30) between the first ball tracks (8) and the second ball tracks (23), wherein one shaft (2, 3) has inner ball tracks and the other shaft (3, 2) has outer ball tracks, and wherein the sleeve (24) has inner third ball tracks (25) and outer third ball tracks (25). Shaft coupling (1) according to one of the preceding claims, wherein the first shaft (2) has a plurality of second sections (7) which are arranged adjoining one another along the axis of rotation (5). Shaft coupling (1) according to one of the preceding claims, wherein a cage (31) is arranged between the sleeve (24) and each shaft (2, 3), wherein the balls (12, 13, 26) are arranged at fixed distances (33) to each other via the cage (31) at least relative to an axial direction (32) extending along the axis of rotation (5). Shaft for a shaft coupling according to one of the preceding claims, wherein the shaft has on a circumferential surface (4) a plurality of first ball tracks (8) extending along an axis of rotation (5) over at least a first section (6) and a second section (7), the first ball tracks being spaced apart from one another along a circumferential direction (9) in the first section (6) by first webs (10) and in the second section (7) by second webs (11); wherein the first ball tracks (8) are connected to one another in the first section (6) via first openings (14) arranged in alignment with one another along the circumferential direction (9) and in the second section (7) via second openings (15) arranged in alignment with one another along the circumferential direction (9);wherein in the first section (6) a first end face (16) of the first webs (10) pointing towards the first openings (14) is smaller than in the second section (7) a second end face (17) pointing towards the second openings (15).;

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