Shaft coupling and shaft for shaft coupling

Abstract

The shaft coupling (1) is for switchably connecting a first shaft (2) and a second shaft (3) arranged coaxially with each other. The shaft coupling (1) comprises at least the first shaft (2), which has a plurality of first ball tracks (8) on a circumferential surface (4). Each of the first ball tracks (8) extends along the rotation axis (5) at least through a first section (6) and a second section (7). Each of the first ball tracks (8) is spaced apart from each other along a circumferential direction (9) by a plurality of first webs (10) in the first section (6) and by a plurality of second webs (11) in the second section (7). The shaft coupling (1) further comprises 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).

Description

Technical Field

[0001] The present invention relates to a shaft coupling for switchably connecting a first shaft and a second shaft that are coaxially arranged with each other and have a common rotation axis. Further, the present invention relates to the shafts of the shaft coupling. Through the shaft coupling, the shafts are either non-rotatably connected to each other to transmit torque (i.e., cannot rotate relative to each other) (connected position), or separated from each other (separated position). In the separated position, the shafts can rotate independently of each other and no torque is transmitted.

Background Art

[0002] Patent Document 1 discloses a shaft coupling for switchably connecting a first shaft and a second shaft. Each shaft has a bolt track that mates with the bolt track of the sleeve. Each ball is displaced by moving the sleeve along the rotation axis. An opening is provided between the bolt tracks on one side of each shaft, and each ball can be displaced therein. When each ball is arranged in the region of the opening, the shafts can rotate independently of each other. When each ball is arranged outside the opening, i.e., between the webs of the bolt tracks, the shafts are connected to each other.

[0003] In this type of shaft coupling, the individual ball tracks of the shaft are arranged at an angular distance from each other along the circumferential direction. Therefore, in order to change from the separation position to the connection position, these angular distances must be bridged, and as a result, each ball can be moved within each ball track or within the area between the webs. If the angular distance is relatively large, a long switching time is required to reach the connection position. The switching is only possible within a very small angular range, which is determined by the (surplus) size of the inlet opening of the ball track with respect to the ball. Furthermore, this severely limits the allowable rotational speed difference between the shafts to be connected for switching.

[0004] However, widening the inlet opening or widening the width of the ball track cannot be done because it deteriorates the NVH (noise, vibration, harshness) behavior of the shaft coupling (due to the increased play of the balls in the ball track in the circumferential direction). Reducing the angular distance, for example increasing the number of ball tracks, causes a decrease in the transmissible torque. Reducing the angular distance when the effective diameter is large (the ball tracks are arranged on a larger diameter of the shaft) often increases the installation space requirements and makes it impossible to install.

[0005] Patent Document 2 discloses a coupling provided with a switching sleeve.

[0006] Patent Document 3 discloses a longitudinal displacement unit for connecting two shafts.

[0007] Patent Document 4 discloses a device for generating and releasing a connection fixed in terms of the rotational direction between two shafts.

[0008] Patent Document 5 discloses a vibration isolation device capable of connecting two shafts to each other.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0010] The object of the present invention is to at least partially solve the problems detailed with respect to the prior art. In particular, a small shaft coupling capable of transmitting a large torque is proposed. In particular, it realizes shortening the operating distance and reducing the switching force. Furthermore, even when there is a large difference in the rotational speed of each shaft, the shaft coupling can be switched.

Means for Solving the Problems

[0011] A shaft coupling having the features according to claim 1 and a shaft having the features according to claim 11 contribute to the solution of these problems. In the dependent claims, advantageous developments are detailed. The features detailed individually in the claims can be combined in technically suitable manners and are complemented by the explanatory technical content of this specification and the details of the figures, which detail further variants of the present invention.

[0012] A shaft coupling for switchably connecting a first shaft and a second shaft is proposed. These shafts are arranged coaxially with each other and have a common axis of rotation.

[0013] The shaft coupling includes at least a first shaft, a plurality of first balls, and a plurality of second balls. The first shaft has a plurality of first ball tracks on its circumferential surface, and these first ball tracks extend along the rotation axis over at least a first region and a second region. Each first ball track is arranged at intervals along the circumferential direction by a first web in the first region and by a second web in the second region. The plurality of first balls are arranged in the first region (at any position of the shaft coupling). The plurality of second balls are arranged in the second region (at any position of the shaft coupling). The first ball tracks are connected to each other. In the first region, they are connected through a plurality of first openings arranged side by side along the circumferential direction. In the second region, they are connected through a plurality of second openings arranged side by side along the circumferential direction.

[0014] The shaft coupling is only switchable between two positions. Each ball is displaceable along each ball track within its respective region between the aforementioned positions. Each ball is arranged side by side with each web when in the connected position and side by side with each opening when in the separated position in the circumferential direction. The first end face of each first web facing each first opening in the first region is smaller than the second end face of each second web facing each second opening in the second region.

[0015] The proposed shaft coupling is small in size while enabling high torque transmission. The torque can be transmitted through a large number of balls.

[0016] Each ball track extends particularly parallel to the axis of rotation and preferably extends perpendicular to the circumferential direction. Each ball track has a track base sandwiched on both sides by track side walls formed by webs. The track base extends particularly at a certain distance from the axis of rotation and preferably extends parallel to the axis of rotation. The track base is arranged at either the minimum diameter or the maximum diameter of the ball track. Each side wall of the track supports each ball with respect to the circumferential direction. A web having an end face is arranged between the side walls of adjacent ball tracks.

[0017] In particular, several balls are arranged in each first ball track, preferably two or more balls are arranged.

[0018] During the operation of the shaft coupling, each first ball is particularly always arranged in the first area, and the second ball is always arranged in the second area. When the shaft coupling is switched, each ball is displaced within its respective area along the axis of rotation. Therefore, when each ball is arranged in its respective opening at the separation position of the shaft coupling, each ball can be moved along the circumferential direction relative to the first shaft. Therefore, the first shaft can rotate freely with respect to each ball. To switch the shaft coupling to the connected position, each ball enters the ball track of its respective area. At the connected position, since each ball is aligned with the web in the circumferential direction, it is impossible for the first shaft to rotate with respect to each ball.

[0019] By making the size of the first end face smaller than that of the second end face, each first ball can more easily enter the first ball track. In particular, the angular distance between the two first ball tracks is actually reduced in this way. Also, thereby, the clearance with respect to the circumferential direction between each web of the first ball track and each first ball increases, at least in the region of the first end face.

[0020] On the one hand, this may increase the difference in rotational speeds between the shafts to be connected when connecting the shafts. On the other hand, due to the reduced angular distance, the switching time for making the connection is shortened.

[0021] The first end face of each first web is made small, in particular, such that the inlet opening of the first bolt track is enlarged. In particular, the inlet opening of the first bolt track is enlarged in the circumferential direction. The first inlet opening is enlarged by at least 2%, preferably at least 4%, particularly preferably at least 8% compared to the second inlet opening of the first bolt track in the second region.

[0022] In particular, the chamfered portion is adjacent to the first end face of the first web. In particular, the chamfered portion is inclined toward one of the first bolt tracks arranged adjacent to the first web. The chamfered portion forms the first inlet opening of the first bolt track. This first inlet opening is enlarged in the circumferential direction. By the chamfered portion, the width of the first bolt track gradually becomes narrower from the first inlet opening along the rotation axis. Therefore, the width of the first bolt track that spreads in the circumferential direction is maximum at the position where the first end face is located in the direction along the rotation axis, and gradually becomes narrower from there to the (subsequently constant) minimum width of the first bolt track.

[0023] In particular, the chamfered portions are arranged on each of the first end faces. In particular, these are arranged on the same side wall of each first web.

[0024] The minimum width of the first bolt track in the first region is equal to the (minimum) width of the first bolt track in the second region, in particular. In particular, the first bolt track in the second region has a constant width.

[0025] In particular, the chamfered portion consists of a recess of the edge that forms a transition portion between the end face and the side wall of the web. The end face existing at the position along the rotation axis determines the size or width of the inlet opening of the first bolt track, in particular.

[0026] In particular, the two chamfered portions are adjacent to the first end face of the first web. In particular, each chamfered portion is inclined toward a different one of the first ball tracks arranged adjacent to the first web. Each chamfered portion forms a first inlet opening of each first ball track. This first inlet opening is enlarged in the circumferential direction. By each chamfered portion, the width of each first ball track gradually narrows from the first inlet opening along the axis of rotation.

[0027] In particular, the two chamfered portions are arranged on each of the first end faces.

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

[0029] In particular, at the separation position, each first ball is arranged at a first distance from each first end face along the axis of rotation, and each second ball is arranged at a second distance from each second end face along the axis of rotation. In particular, the first distance is smaller than the second distance.

[0030] The difference between the first distance and the second distance is in particular dimensioned such that each first ball first exits the first opening along the axis of rotation and enters the first ball track (via the enlarged first inlet opening). By the width gradually narrowing from the first inlet opening, each first ball gradually aligns with the first ball track as the displacement of each first ball along the axis of rotation progresses. In particular, for the second distance, it is designed such that when each first ball in the first area reaches the minimum width, only each second ball can enter the first ball track in the second area from each second opening.

[0031] This facilitates passing each first ball through the first area. By passing only each first ball through each first ball track and then aligning each first ball well with the first shaft via each chamfered portion, each second ball can be aligned with the first ball track in the second area. This can shorten the switching time and simplify the switching process. In this process, torque transmission is not impaired.

[0032] In particular, the shaft coupling further includes at least a second shaft having a plurality of second ball tracks extending along the rotation axis, and a sleeve having a plurality of third ball tracks. This sleeve at least partially covers each first ball track and each second ball track along the rotation axis. Further, the shaft coupling further has a plurality of third balls. Each first and second ball is arranged in a first track pair formed by each first ball track and each third ball track, and each third ball is arranged in a second track pair formed by each second ball track and each third ball track. Each ball can be displaced between the aforementioned positions along each ball track by displacing the sleeve along the rotation axis. As a result, at the connection position, the shafts are non-rotatably connected to each other, and at the separation position, the first shaft and the second shaft are relatively rotatable.

[0033] In particular, each ball is moved along the shaft as part of a rolling motion (and not as a sliding motion). By each ball rolling, it is possible to operate the shaft coupling with a small force.

[0034] In particular, the shafts are arranged adjacent to each other along the rotation axis, and the sleeve extends radially outward beyond each first and second ball track. Each third ball track forms an outer (i.e., radially outwardly arranged) ball track and forms a first track pair with each inner (i.e., radially inwardly arranged) first ball track, and forms a second track pair with each inner second ball track.

[0035] In another aspect, the plurality of first ball tracks and the plurality of second ball tracks overlap along the axis of rotation, and the sleeve is disposed between the first and second ball tracks along the radial direction. One shaft has a plurality of inner (disposed radially inward) ball tracks, and the other shaft has a plurality of outer (disposed radially outward) ball tracks. The sleeve has a plurality of inner third ball tracks and a plurality of outer third ball tracks.

[0036] In particular, the first shaft has a plurality of second regions disposed adjacent to each other along the axis of rotation.

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

[0038] The distance between each ball disposed in each second ball track can be designed to be different from the distance between each ball disposed in each first ball track (however, it is also possible to make them the same).

[0039] In particular, each (respective) cage is not connected to the sleeve, but is displaced axially along each ball. Since each ball is always disposed in each third ball track, the cage rotates with the sleeve. By displacing the sleeve, it is possible to displace, in particular (exclusively) as part of the rolling motion, in particular each ball and the cage via each ball, axially. Thereby, each ball can be displaced within the aforementioned region to realize the separation position or the connection position of the shaft joint.

[0040] In particular, only each first ball track is connected to each other along the circumferential direction via an opening portion. Each first ball track is connected to each other via each first opening portion in the first region, and is connected to each other via each second opening portion along the circumferential direction in the second region. Thereby, each first and second ball can be displaced along the circumferential direction on a diameter (corresponding to the track base of the first ball track) along the circumferential direction. Each first opening portion in the first region and each second opening portion in the second region are arranged side by side with each other, particularly along the circumferential direction. Therefore, each opening portion in each region forms a ball track that extends only in the circumferential direction.

[0041] By displacing the sleeve along the rotation axis, each first and second ball can be displaced along each (first, second, and third) ball track, and each first and second ball can be arranged in each opening portion. Thereby, each ball can be displaced along the ball track formed by the opening portion and extending in the circumferential direction, and each ball can be displaced along the circumferential direction with respect to the first shaft. Thereby, the sleeve and the second shaft can be rotated with respect to the first shaft. In particular, all the balls arranged on the first shaft must be arranged in such a region having an opening portion, whereby the sleeve having each ball arranged on each first ball track can be rotated with respect to the first shaft.

[0042] When each ball arranged on each first ball track is arranged along the circumferential direction outside the opening portion and side by side with the web, each shaft is non-rotatably connected to each other.

[0043] In particular, a plurality of rows of each ball are arranged in at least one of a plurality of track pairs. At this time, each ball in one row is arranged at a position along the rotation axis and adjacent to each other in the circumferential direction. In particular, the number of rows on the first shaft corresponds to the number of (first and second) regions provided on the first shaft.

[0044] In particular, the sleeve is displaceable relative to the shaft along an axial direction extending along the axis of rotation by means of an actuating device.

[0045] Various actuating devices can be used. Since the friction between the ball and the ball track is low (due to rolling friction which is lower than sliding friction), the actuating force required to switch the shaft coupling is small.

[0046] A (first) shaft for the shaft coupling described is also proposed. The shaft has a plurality of first ball tracks on its circumferential surface, and these first ball tracks extend along the axis of rotation over at least a first region and a second region. The first ball tracks are arranged at intervals from each other along the circumferential direction by a first web in the first region and by a second web in the second region. The first ball tracks are connected to each other. In the first region, they are connected via a plurality of first openings arranged side by side along the circumferential direction. In the second region, they are connected via a plurality of second openings arranged side by side along the circumferential direction. The first end face of each first web facing each first opening in the first region is smaller than the second end face of each second web facing each second opening in the second region.

[0047] The description of the shaft coupling, in particular the description of the first shaft described in relation thereto, is particularly applicable to the shaft, and vice versa.

[0048] In particular, reference is made to the shaft coupling according to Patent Document 1. The description given in Patent Document 1 regarding the device with the first shaft, the second shaft, the sleeve, and the cage is particularly applicable to the shaft device described here.

[0049] In particular, in the claims and the recitations of these claims, the indefinite articles ("ein", "eine", "einer", "eines") are not used as numerals and are intended to be understood as such. Accordingly, the terms and components introduced in correspondence therewith are intended to be understood as being present at least once, but in particular may also be present several times.

[0050] For the sake of avoiding ambiguity, the ordinal numbers ("first", "second", etc.) used in this specification are mainly provided only for distinguishing several similar objects, numerical values, steps, i.e., in particular, these ordinal numbers do not necessarily define any dependency or order among these objects, numerical values, steps. If a dependency or order is required, this will be specified in this specification or will become apparent to those skilled in the art by examining the actually described configuration. When components can occur one or more times ("at least one"), a description of one of these components may apply equally to all or some of these multiple components, but not necessarily so.

[0051] Hereinafter, with reference to the accompanying drawings, the present invention and the technical background will be described in more detail. It should be noted that the present invention is not intended to be limited by the embodiments described in detail. Unless otherwise specified, in particular, it is also possible to extract partial features of the technical content described in the figures and combine them with other components and the knowledge of this specification. In particular, it should be noted that the figures and especially the illustrated ratios are merely schematic.

Brief Description of the Drawings

[0052] The drawings show the following.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0053] FIG. 1 is a side view of the shaft coupling, showing a part of the cross section. The shaft coupling 1 is used to switchably connect the first shaft 2 and the second shaft 3. These shafts are arranged coaxially with each other and have a common rotation axis 5.

[0054] The shaft coupling 1 includes a first shaft 2, a plurality of first balls 12, and a plurality of second balls 13. The first shaft 2 has a plurality of first ball tracks 8 on its circumferential surface 4, and these first ball tracks 8 extend along the rotation axis 5 over at least a first region 6 and a second region 7. Each first ball track 8 is arranged at intervals from each other along the circumferential direction 9 by each first web 10 in the first region 6 and by each second web 11 in the second region 7. The plurality of first balls 12 are arranged in the first region 6 (at any position of the shaft coupling 1). The plurality of second balls 13 are arranged in the second region 7 (at any position of the shaft coupling 1). The first ball tracks 8 are connected to each other. In the first region 6, they are connected via a plurality of first openings 14 (not shown here, see FIG. 9) arranged side by side along the circumferential direction 9. In the second region 7, they are connected via a plurality of second openings 15 arranged side by side along the circumferential direction 9.

[0055] The shaft coupling 1 is switchable only between two positions. The balls 12, 13 are displaceable along the ball tracks 8, 23 between the aforementioned positions within their respective regions 6, 7. The balls 12, 13 are arranged side by side with the webs 10, 11 when in the connected position in the circumferential direction 9 (shown here), and are arranged side by side with each opening 14, 15 when in the separated position (shown here). The first end face 16 (see FIG. 9) of each first web 10 facing each first opening 14 in the first region 6 is smaller than the second end face 17 of each second web 11 facing each second opening 15 in the second region 7.

[0056] The shaft coupling 1 further includes a second shaft 3 having a plurality of second ball tracks 23 extending along the rotation axis 5, and a sleeve 24 having a plurality of third ball tracks 25. The sleeve 24 at least partially covers each of the first ball tracks 8 and each of the second ball tracks 23 along the rotation axis 5. Further, the shaft coupling 1 further has a plurality of third balls 26. Each of the first and second balls 12, 13 is disposed in a first track pair 27 formed by each of the first ball tracks 8 and each of the third ball tracks 25, and each of the third balls 26 is disposed in a second track pair 28 formed by each of the second ball tracks 23 and each of the third ball tracks 25. Each of the balls 12, 13, 26 can be displaced between the aforementioned positions along each of the ball tracks 8, 23, 25 by displacing the sleeve 24 along the rotation axis 5. As a result, at the connection position, the shafts 2, 3 are non-rotatably connected to each other, and at the separation position, the shafts 2, 3 are relatively rotatable.

[0057] The shafts 2, 3 are arranged adjacent to each other along the rotation axis 5, and the sleeve 24 extends radially 30 outward beyond the first and second ball tracks 8, 23. Each of the third ball tracks 26 forms an outer (i.e., disposed radially 30 outward) ball track and forms a first track pair 27 together with the inner (i.e., disposed radially 30 inward) first ball track 8, and forms a second track pair 28 together with the inner second ball track 23.

[0058] The first shaft 2 has a plurality of second regions 7 arranged adjacent to each other along the rotation axis 5.

[0059] A cage 31 is disposed between the sleeve 24 and each of the shafts 2, 3, and the plurality of (first and second) balls 12, 13 are disposed at a determined distance 33 from each other via the cage 31 with respect to the axial direction 32 extending along the rotation axis 5.

[0060] During the operation of the shaft coupling 1, each first ball 12 is always arranged in the first area 6, and the second ball 13 is always arranged in the second area 7. When the shaft coupling 1 is switched, each ball 12, 13 is displaced within its respective area 6, 7 along the rotation axis 5. Therefore, when each ball 12, 13 is arranged in its respective opening 14, 15 at the separation position of the shaft coupling 1, each ball 12, 13 can be moved relative to the first shaft 2 along the circumferential direction 9. Therefore, the first shaft 2 can rotate freely relative to each ball 12, 13. To switch the shaft coupling 1 to the connected position, each ball 12, 13 enters the first ball track 8 of its respective area 6, 7. At the connected position, since each ball 12, 13 is arranged side by side with the webs 10, 11 in the circumferential direction 9, it is impossible for the first shaft 2 to rotate relative to each ball 12, 13.

[0061] Each ball 12, 13, 26 is assigned to either each first ball track 8 or each second ball track 23. Therefore, the balls 12, 13, 26 are each arranged only in one of the first ball tracks 8 or one of the second ball tracks 23, so that even when the shaft coupling 1 is switched, the balls 12, 13, 26 do not displace from the first shaft 2 to the second shaft 3 or vice versa.

[0062] The sleeve 24 can be displaced relative to the shafts 2, 3 along the axial direction 32 extending along the rotation axis 5 by the actuating device 34. The sleeve 24 can be displaced against the action of the spring element 35, whereby the sleeve 24 can return automatically. The first spring element 35 is realized by a compression spring. Through the actuating device 34, the sleeve 24 can be displaced against the spring force in the direction of displacement 29 from the initial position (see the position of the sleeve 24 shown by the dashed line in FIG. 1) to switch the shaft coupling 1, so that the sleeve 24 can return to the initial position only by the spring force.

[0063] Figure 2 is a side view of the shaft coupling 1 in a separated state, showing a part of the cross-section. Figure 3 shows a side view of the shaft coupling 1 in Figure 2. Figures 2 and 3 will be described together below. Refer to the description of Figure 1.

[0064] The shafts 2 and 3 are arranged coaxially with each other and have a common rotation axis 5. The shaft coupling 1 includes a first shaft 2, a plurality of first balls 12, and a plurality of second balls 13. The first shaft 2 has a plurality of first ball tracks 8 on its peripheral surface 4, and these first ball tracks 8 extend along the rotation axis 5 over at least a first region 6 and a second region 7. The shaft coupling 1 further includes a second shaft 3 having a plurality of second ball tracks 23 extending along the rotation axis 5, and a sleeve 24 having a plurality of third ball tracks 25. The sleeve 24 at least partially covers each first ball track 8 and each second ball track 23 along the rotation axis 5. Further, the shaft coupling 1 further has a plurality of third balls 26.

[0065] In contrast to Figure 1, here, two rows of each of the balls 12, 13, 26 are arranged in each of the track pairs 27, 28. Each of the balls 12, 13 is arranged in two regions 6, 7 of each first ball track 8, that is, of the first shaft 2. Each first ball track 8 is connected to each other via a first opening 14 in the first region 6, and is connected to each other via a second opening 15 along the circumferential direction 9 in the second region 7. The regions 6, 7 are arranged adjacent to each other along the axial direction 32. Therefore, when each of the balls 12, 13 is arranged side by side with each of the webs 10, 11, torque can be transmitted between the sleeve 24 and the first shaft 2 via each of the balls 12, 13. When each of the balls 12, 13 is arranged side by side with each of the openings 14, 15, each of the balls 12, 13 can rotate freely or be displaced along the circumferential direction 9 with respect to the first shaft 2 together with the second shaft 3, the sleeve 24, and the cage 31.

[0066] A cage 31 is disposed between the sleeve 24 and the shafts 2 and 3, whereby the plurality of balls 12, 13, 26 are arranged at a determined distance 33 from each other via the cage 31 with respect to the axial direction 32 extending along the rotation axis 5.

[0067] The cage 31 is not connected to the sleeve 24 but is displaced along the axial direction 32 via each of the balls 12, 13, 26 displaced by the sleeve 24. The sleeve 24 has a plurality of stopping portions 36, and by these stopping portions 36, the cage 31 is supported with respect to the axial direction 32. The cage 31 can be aligned with the sleeve 24 along the axial direction 32 by the stopping portions 36.

[0068] Since each of the balls 12, 13, 26 is always disposed in each of the third ball tracks 25, the cage 31 rotates together with the sleeve 24. The cage 31 is displaceable along the axial direction 32 via the displacement 29, and each of the balls 12, 13, 26 is displaceable along the axial direction 32 via the sleeve 24. Thereby, each of the balls 12, 13 can be displaced within the regions 6, 7 to realize the separation position of the shaft coupling 1 (see FIG. 2).

[0069] FIG. 4 shows a first design modification of the first shaft 2 as seen along the rotation axis 5. FIG. 5 shows a second design modification of the first shaft 2 as seen along the rotation axis 5. FIG. 6 shows a third design modification of the first shaft 2 as seen along the rotation axis 5. Refer to the description of FIGS. 1 to 3. FIGS. 4 to 6 will be collectively described below.

[0070] In the shaft coupling 1, the individual first ball tracks 8 of the first shaft 2 are arranged at an angular distance 37 from each other along the circumferential direction 9 (see Fig. 4). Therefore, these angular distances 37 must be bridged in order to change from the separated position to the connected position. As a result, each ball 12, 13 can be moved within each first ball track 8 or within the region between the webs 10, 11. If the angular distance 37 is relatively large, a long switching time is required to reach the connected position. The switching is only possible within a very small angular range 38, which is determined by the (surplus) size of the first inlet opening 19 of the first ball track 8 with respect to the balls 12, 13. Furthermore, this severely limits the allowable rotational speed difference between the shafts 2, 3 to be connected for switching.

[0071] However, widening the first inlet opening 19 or widening the width 20 of the first ball track 8 cannot be done because the NVH (noise, vibration, harshness) behavior of the shaft coupling 1 deteriorates (because the play of each ball 12, 13 within each first ball track 8 increases with respect to the circumferential direction 9). Reducing the angular distance 37, for example by increasing the number of first ball tracks 8 (see Fig. 5), causes a decrease in the transmissible torque. Reducing the angular distance 37 when the effective diameter 39 is large (each first ball track 8 is arranged on a larger diameter of the first shaft 2, see Fig. 6) often increases the installation space requirements and makes it impossible to install.

[0072] Fig. 7 shows in detail a known shaft coupling 1 in the separated position as seen along the radial direction 30. Fig. 8 shows the details in Fig. 7 of the shaft coupling 1 in the connected position as seen along the radial direction 30. Figs. 7 and 8 will be described together below.

[0073] The shaft coupling 1 includes a first shaft 2, a plurality of first balls 12, and a plurality of second balls 13. The first shaft 2 has a plurality of first ball tracks 8 on its circumferential surface 4, and these first ball tracks 8 extend along the rotation axis 5 over at least a first region 6 and a second region 7. The shaft coupling 1 further includes a second shaft 3 having a plurality of second ball tracks 23 extending along the rotation axis 5, and each third ball 26 is disposed in these second ball tracks 23.

[0074] The first ball tracks 8 are spaced apart from each other along the circumferential direction 9 by respective first webs 10 in the first region 6 and by respective second webs 11 in the second region 7. The plurality of first balls 12 are disposed in the first region 6 (at any position of the shaft coupling 1). The plurality of second balls 13 are disposed in the second region 7 (at any position of the shaft coupling 1). The first ball tracks 8 are connected to each other. In the first region 6, they are connected via a plurality of first openings 14 arranged side by side along the circumferential direction 9. In the second region 7, they are connected via a plurality of second openings 15 arranged side by side along the circumferential direction 9.

[0075] The shaft coupling 1 is switchable only between two positions. The balls 12, 13 are displaceable along the ball tracks 8, 23 within their respective regions 6, 7 between the aforementioned positions. The balls 12, 13 are arranged side by side with the webs 10, 11 when in the connected position in the circumferential direction 9 (Fig. 8), and are arranged side by side with the respective openings 14, 15 when in the separated position (Fig. 7). The first end face 16 of each first web 10 facing each first opening 14 is designed in the same way as the second end face 17 of each second web 11 facing each second opening 15 in the second region 7.

[0076] In the separated position, each first ball 12 is arranged along the rotation axis 5 at a first distance 21 from the first end face 16, and each second ball 13 is arranged at a second distance 22 of the same magnitude from the second end face 17.

[0077] When displacement 29 occurs along the first ball track 8 for each of the balls 12, 13, at the same time, each of the balls 12, 13 is screwed into the region of each first ball track 8 delimited by the webs 10, 11 with respect to the circumferential direction 9.

[0078] FIG. 9 shows the details of the shaft coupling 1 in the separated position as seen along the radial direction 30. Refer to the description of FIGS. 1 - 8.

[0079] The shaft coupling 1 includes a first shaft 2, a plurality of first balls 12, and a plurality of second balls 13. The first shaft 2 has a plurality of first ball tracks 8 on its circumferential surface 4, and these first ball tracks 8 extend along the rotation axis 5 over at least the first region 6 and the second region 7. The shaft coupling 1 further includes a second shaft 3 having a plurality of second ball tracks 23 extending along the rotation axis 5, and each third ball 26 is disposed in these second ball tracks 23.

[0080] The balls 12, 13 are displaceable along the first ball track 8 between the aforementioned positions within their respective regions 6, 7. The balls 12, 13 are arranged side by side with the openings 14, 15 in the circumferential direction 9 at the shown separated positions. The first end face 16 of each first web 10 facing each first opening 14 in the first region 6 is smaller than the second end face 17 of each second web 10 facing each second opening 15 in the second region 7.

[0081] By making the size of the first end face 16 smaller than that of the second end face 17, it is possible to make it easier for each first ball 12 to enter the first ball track 8 (or the region between each first web 10). In particular, the angular distance 37 (shown here) between two adjacent first ball tracks 8 is actually reduced in this way. Also, thereby, the clearance in the circumferential direction 9 between each first web 10 of the first ball track 8 and each first ball 12 increases at least in the region of the first end face 16.

[0082] The first end face 16 of each first web 10 is made smaller so that the first inlet opening 19 of the first ball track 8 is enlarged. The first inlet opening 19 of the first ball track 8 is enlarged in the circumferential direction 9.

[0083] The chamfered portion 18 is adjacent to the first end face 16 of the first web 10. The chamfered portion 18 is inclined toward one of the first ball tracks 8 disposed adjacent to the first web 10. The chamfered portion 18 forms the first inlet opening 19 of the first ball track 8. This first inlet opening 19 is enlarged in the circumferential direction 9. By the chamfered portion 18, the width 20 of the first ball track 8 gradually becomes narrower from the first inlet opening 19 along the rotation axis 5. Accordingly, the width 20 of the first ball track 8 that spreads in the circumferential direction 9 is maximum at the position where the first end face 16 is located with respect to the direction along the rotation axis 5, and gradually becomes narrower from there to the minimum width 20 (which then becomes constant) of the first ball track 8.

[0084] The minimum width 20 of the first ball track 8 in the first region 6 is the same size as the minimum and constant width 20 of the first ball track 8 in the second region 7.

[0085] The chamfered portion 18 consists of a recess at the edge that forms a transition portion between the first end face 16 and the track side wall of the first web 10.

[0086] In the separated position, each first ball 12 is disposed at a first distance 21 from each first end face 16 along the rotation axis 5, and each second ball 13 is disposed at a second distance 22 from each second end face 17 along the rotation axis 5. The second distance 22 is greater than the first distance 21.

[0087] The difference between the first distance 21 and the second distance 22 is dimensioned such that each first ball 12 first exits the first opening 14 along the axis of rotation 5 and enters the first ball track 8 through the enlarged first inlet opening 19. As the width 20 gradually narrows from the first inlet opening 19, each first ball 12 gradually aligns with the first ball track 8 as the displacement 29 of each first ball 12 along the axis of rotation 5 progresses. Regarding the second distance 22, it is designed such that when each first ball 12 in the first area 6 reaches the minimum width 20, only each second ball 13 can enter the first ball track 8 in the second area 7 from each second opening 15.

[0088] This facilitates passing each first ball 12 through the first area 6. By passing only each first ball 12 through the first ball track 8 and then properly aligning each first ball 12 with respect to the first shaft 2 through each chamfered portion 18, each second ball 13 can be aligned with the first ball track 8 in the second area 7. This can shorten the switching time and simplify the switching process. In this process, torque transmission is not impaired.

Explanation of Reference Numerals

[0089] 1 Shaft coupling 2 First shaft 3 Second shaft 4 Peripheral surface 5 Axis of rotation 6 First area 7 Second area 8 First ball track 9 Circumferential direction 10 First web 11 Second web 12 First ball 13 Second ball 14 First opening 15 Second opening 16 First end face 17 Second end face 18 Chamfered portion 19 First inlet opening 20 images 21 First distance 22 Second distance 23 Second bolt track 24 Sleeve 25 Third bolt track 26 Third ball 27 First track pair 28 Second track pair 29 Displacement 30 Radial direction 31 Cage 32 Axial direction 33 Distance 34 Actuator 35 Spring element 36 Stop part 37 Angular distance 38 Angular range 39 Effective diameter

Claims

1. A shaft coupling (1) for switchably connecting a first shaft (2) and a second shaft (3) arranged coaxially with each other, the shaft coupling (1) comprises at least the first shaft (2), the first shaft (2) has a plurality of first ball tracks (8) on its circumferential surface (4), each of the first ball tracks (8) extends along the rotation axis (5) over at least a first region (6) and a second region (7), each of the first ball tracks (8) is arranged at intervals from each other along the circumferential direction (9) by a plurality of first webs (10) in the first region (6) and by a plurality of second webs (11) in the second region (7), the shaft coupling (1) is, a plurality of first balls (12) arranged in the first region (6), and a plurality of second balls (13) arranged in the second region (7), further comprising, each of the first ball tracks (8) is, in the first region (6), connected to each other along the circumferential direction (9) through a plurality of first openings (14) arranged side by side along the circumferential direction (9), and, in the second region (7), connected to each other along the circumferential direction (9) through a plurality of second openings (15) arranged side by side along the circumferential direction (9), the shaft coupling (1) is switchable between at least two positions, each of the balls (12, 13) is displaceable between the two positions along each of the ball tracks (8) within its respective region (6, 7), the balls (12, 13) are, in the circumferential direction (9), arranged side by side with each of the webs (10, 11) at the connection position, and, arranged side by side with each of the openings (14, 15) at the separation position, a first end face (16) of each of the first webs (10) facing each of the first openings (14) in the first region (6) is smaller than a second end face (17) of each of the second webs (11) facing each of the second openings (15) in the second region (7), characterized by the shaft coupling.

2. The shaft coupling (1) according to claim 1, a chamfered portion (18) is adjacent to the first end face (16) towards at least one of the first ball tracks (8) arranged adjacent to the first web (10). The chamfered portion (18) forms a first inlet opening (19) of at least one of the plurality of first ball tracks (8). The first inlet opening (19) is enlarged in the circumferential direction (9). The width (20) of the first ball track (8) gradually narrows from the first inlet opening (19) along the rotation axis (5) by the chamfered portion (18). A shaft coupling characterized by the above.

3. The shaft coupling (1) according to claim 1 or 2, Towards both of the first ball tracks (8) arranged adjacent to the first web (10), the chamfered portion (18) is adjacent to the first end face (16). The chamfered portion (18) forms a first inlet opening (19) of the plurality of first ball tracks (8). The first inlet opening (19) is enlarged in the circumferential direction (9). The widths (20) of the plurality of first ball tracks (8) gradually narrow from the first inlet opening (19) along the rotation axis (5) by the plurality of chamfered portions (18). A shaft coupling characterized by the above.

4. The shaft coupling (1) according to any one of claims 1 to 3, The first end face (16) is at most 95% of the second end face (17). A shaft coupling characterized by the above.

5. The shaft coupling (1) according to any one of claims 1 to 4, At the separation position, The plurality of first balls (12) are arranged at a first distance (21) from the plurality of first end faces (16) along the rotation axis (5), and The plurality of second balls (13) are arranged at a second distance (22) from the plurality of second end faces (17) along the rotation axis (5). The first distance (21) is smaller than the second distance (22). A shaft coupling characterized by the above.

6. The shaft coupling (1) according to any one of claims 1 to 5, The shaft coupling (1) is The second shaft (3) having a plurality of second ball tracks (23) extending along the rotation axis (5), And a sleeve (24) that at least partially covers the plurality of first ball tracks (8) and the plurality of second ball tracks (23) along the rotation axis (5). At least includes The sleeve (24) has a plurality of third ball tracks (25) and a plurality of third balls (26). The plurality of first and second balls (12, 13) are arranged in a first track pair (27) formed by each of the first ball tracks (8) and each of the third ball tracks (25), The plurality of third balls (26) are arranged in a second track pair (28) formed by each of the second ball tracks (23) and each of the third ball tracks (25), Each of the balls (12, 13, 26) is displaceable between the two positions along each of the ball tracks (8, 23, 25) by a displacement (29) along the rotation axis (5) of the sleeve (24), As a result, at the connection position, the shafts (2, 3) are non-rotatably connected to each other, and at the separation position, they are relatively rotatable, A shaft coupling, characterized in that.

7. The shaft coupling (1) according to claim 6, The shafts (2, 3) are arranged side by side along the rotation axis (5), The sleeve (24) extends radially (30) outward beyond the first ball track (8) and the second ball track (23), Each of the third ball tracks (25) Forms a plurality of outer ball tracks, Forms the first track pair (27) together with each of the inner first ball tracks (8), Forms the second track pair (28) together with each of the inner second ball tracks (23), A shaft coupling, characterized in that.

8. The shaft coupling (1) according to claim 6, The plurality of first ball tracks (8) and the plurality of second ball tracks (23) overlap along the rotation axis (5), The sleeve (24) is arranged between the plurality of first ball tracks (8) and the plurality of second ball tracks (23) along the radial direction (30), One of the shafts (2, 3) has a plurality of inner ball tracks, The other of the shafts (3, 2) has a plurality of outer ball tracks, The sleeve (24) has a plurality of inner third ball tracks (25) and a plurality of outer third ball tracks (25), A shaft coupling, characterized in that.

9. The shaft coupling (1) according to any one of claims 1 to 8, The first shaft (2) has a plurality of second regions (7) arranged adjacent to each other along the rotation axis (5), A shaft coupling, characterized in that.

10. The shaft coupling (1) according to any one of claims 1 to 9, wherein the cage (31) is disposed between the sleeve (24) and the shafts (2, 3) respectively, each of the balls (12, 13, 26) is arranged at a determined distance (33) from each other via the cage (31) with respect to the axial direction (32) extending at least along the rotation axis (5), characterized in that it is a shaft coupling.

11. A shaft for a shaft coupling according to any one of claims 1 to 10, wherein the shaft has a plurality of first ball tracks (8) on the circumferential surface (4), each of the first ball tracks (8) extends along the rotation axis (5) over at least a first region (6) and a second region (7), each of the first ball tracks (8) is arranged at intervals from each other along the circumferential direction (9) by a plurality of first webs (10) in the first region (6) and by a plurality of second webs (11) in the second region (7), each of the first ball tracks (8) in the first region (6) is connected to each other along the circumferential direction (9) via a plurality of first openings (14) arranged side by side along the circumferential direction (9), and in the second region (7) is connected to each other along the circumferential direction (9) via a plurality of second openings (15) arranged side by side along the circumferential direction (9), a first end face (16) of each of the first webs (10) facing each of the first openings (14) in the first region (6) is smaller than a second end face (17) of each of the second webs (11) facing each of the second openings (15) in the second region (7), characterized in that it is a shaft.

Images