MULTI-CHAINING ARRANGEMENT FOR A SINGLE REAR HUB

Description

[0001] The invention relates to a multiple sprocket arrangement for a rear wheel hub of a bicycle with improved shifting characteristics, reduced vibrations during skew running and improved wear behavior.

[0002] Document DE 10 2012 023 819 A1 shows a front sprocket for attachment to a bicycle pedal crank, which is characterized by improved chain guidance compared to conventional sprockets. The improved guidance properties mean that additional chain guides can be dispensed with when a single such sprocket is used on a bicycle pedal crank. This applies even if there is no chain guide for a derailleur. This property is of particular advantage for bicycles that are used off-road and where the chain tends to jump off the sprocket due to uneven terrain and sudden steering movements. The improved guidance properties are achieved primarily by the fact that the sprocket has thick and thin teeth, viewed in the axial direction of the pedal crank, which are arranged alternately in the circumferential direction.

[0003] Furthermore, these teeth can be particularly long in the radial direction, with the tooth gaps being only slightly larger in the circumferential direction than the chain rollers they accommodate. It is also possible to provide clearances to accommodate the inner plates of the chain that protrude beyond the chain rollers.

[0004] With this state-of-the-art technology, only one of these sprockets is mounted on each right-hand crank, eliminating the need for a front derailleur. This eliminates the need to transfer the drive roller chain to an adjacent sprocket in the load side, which normally places considerable demands on the chain tension forces present in the load side. These sprockets are unsuitable for use on a rear wheel hub because their exceptionally good chain guidance properties preclude transferring them to an adjacent sprocket.

[0005] Similar sprocket arrangements are also known from the later published patent applications US 2014 / 0338494 A1 and DE 10 2014 019 528 A1.

[0006] However, the gear shifting processes on multiple sprocket arrangements on a pedal crank and the associated requirements differ significantly from those of a multiple sprocket arrangement for a bicycle rear wheel hub. In the case of a driving sprocket (on the pedal crank), the chain roller is always carried by the load flank of the sprocket. The drive direction dictates that the gear shifting process must occur on the load side. In the case of a driven sprocket, for example a pinion of a sprocket cassette attached to a bicycle rear wheel, the chain roller runs on or near the lead-in flank on the slack side of the drive. The chain is guided by the derailleur sprocket, so that the run-in situation on the respective sprocket does not experience any significant skew.This results in completely different tasks for shifting and guiding the chain for a rear sprocket (pinion) on the rear wheel of a bicycle and a front sprocket on the crank. Document TW201404657A shows the preamble of claim 1.

[0007] An object of the present invention is to provide a multiple sprocket assembly for a bicycle rear wheel hub that has improved shifting characteristics, particularly when shifting to smaller-diameter sprockets and during shifting operations with large tooth count differences. Furthermore, the skew characteristics are to be improved and wear reduced.

[0008] This object is achieved by a multiple sprocket arrangement for a rear wheel hub of a bicycle having the features of claim 1.

[0009] Preferred embodiments are apparent from claims 2 to 15.

[0010] A multiple sprocket arrangement for a rear wheel hub of a bicycle comprises a plurality of sprockets with different diameters, each of which, in particular, has an even number of teeth. At least one sequence of teeth is provided on the circumference of at least one of the sprockets, in which, with respect to their material thickness in a direction transverse to the circumferential direction, a thick tooth is arranged next to a thin tooth, followed by another thin tooth. The at least one sprocket has at least one passage recess, in particular in the form of an impression or a recess produced by material removal, which forms at least one shift gate and enables a change from a chain engaged with one of the sprockets to engagement with an adjacent sprocket.

[0011] The shift gate can thus be provided between the teeth of adjacent sprockets as a means for the chain to pass through the teeth on a sprocket with a larger diameter or greater number of teeth, allowing the chain to disengage from the teeth on the sprocket in question and switch to the adjacent sprocket with a smaller diameter or smaller number of teeth. Additionally, a shift gate can also be provided to allow the chain to disengage from the teeth on the smaller sprocket in question and switch to the adjacent sprocket with a larger diameter or greater number of teeth.

[0012] According to one variant, a passage recess can be provided on at least one of the teeth forming a passage tooth of one of the sprockets with a larger diameter for the passage of an inner link plate of the chain for the chain to descend to an adjacent sprocket with a smaller diameter. According to another variant, a passage recess can be provided on at least one of the teeth forming a passage tooth of one of the sprockets with a smaller diameter for the passage of an inner link plate or an outer link plate of the chain for the chain to ascend to an adjacent sprocket with a larger diameter.

[0013] Furthermore, the phase assignment between adjacent sprockets can be configured to establish synchronization between the chain links and corresponding teeth of a sprocket with a smaller diameter. This allows the inner or outer link plates re-engaging on the sprocket with a smaller diameter to meet a corresponding tooth. This ensures that an inner link plate meets a thin tooth and an outer link plate meets a thick tooth. Here, too, "thin" and "thick" refer to the material thickness of the respective tooth viewed in a direction transverse to the circumferential direction of the associated sprocket, i.e., essentially parallel to the direction of the respective axis of rotation.

[0014] The arrangement according to the invention can be such that when the chain is shifted from a larger sprocket to a smaller sprocket, an inner link plate runs laterally past a thin tooth of the sprocket with a larger diameter ("inner link plate passage") so that the chain disengages from the toothing of the sprocket with a larger diameter.

[0015] Accordingly, in a further development of the multiple sprocket arrangement according to the invention, at least one sprocket with a smaller diameter can be phase-aligned relative to an adjacent sprocket with a larger diameter such that, when the chain changes from the sprocket with a larger diameter to the adjacent sprocket with a smaller diameter, synchronization is achieved between the teeth of the sprocket with a smaller diameter and the respective associated chain links of the chain. In other words, the at least one sprocket with a smaller diameter can be rotated relative to the adjacent sprocket with a larger diameter by a specific angle of rotation about a common axis of rotation.The magnitude of the angle of rotation can be determined depending on the chain, the geometry of the teeth, and / or the different diameters of the sprockets to ensure the intended engagement of the chain on the at least one sprocket with a smaller diameter when changing to it from the adjacent sprocket with a larger diameter. In particular, the shift gates can be arranged such that when the chain changes to an adjacent sprocket, an outer link plate always meets a thick tooth.

[0016] In this context, it should be noted that, in one variant of the invention, the relative arrangement of the shifting channels and adjacent sprockets can be selected such that, during a shift of the chain from one sprocket to an adjacent sprocket, the chain strand or chain section running between the two sprockets runs essentially linearly and tangentially to the root circle of the sprocket with the smaller diameter. The aforementioned angle of rotation or angular offset is thus selected such that the distance between the last meshing tooth of the larger sprocket and the first meshing tooth of the smaller sprocket is essentially a multiple of the chain pitch.

[0017] According to a further embodiment, at least the at least one sprocket with a smaller diameter can have several sequences of thick and thin teeth along its circumference with regard to its material thickness in the direction transverse to the circumferential direction.

[0018] According to a further embodiment, at least one tooth of one or more of the plurality of sprockets can have a supporting edge which is designed to support an outer link of the chain radially inwardly with respect to the axis of rotation of the respective associated sprocket.

[0019] The solution approach of a so-called inner link passage, in which the inner links of an inner link pass a tooth on one side before the outer links of the next chain link flank a tooth on both sides, has already been implemented in conventional sprockets. For example, document EP 0 642 972 A1 shows an inner link passage for the chain's descent from the larger to the smaller pinion or sprocket.

[0020] An outer link plate passage for the chain's downward movement from the larger to the smaller sprocket is technically impractical, because this would result in an indentation or shift gate measured in a direction parallel to the rotation axis that would be too deep. Document EP 0 313 345 A1, as well as document DE 44 18 407 A1, describe an inner link passage for the chain's upward movement from the smaller to the larger pinion or sprocket. However, an outer link plate passage for the chain's upward movement from the smaller to the larger pinion or sprocket is also possible and sensible.

[0021] With conventional sprockets, it's only partially possible to ensure that the chain always shifts to the smaller-diameter sprocket at the shift gates. With conventional sprockets, the chain often leaves the gearing on the larger-diameter sprocket if the phase alignment is incorrect. A sufficiently large force on the chain, or a sufficiently large deflection of the chain guide of a rear derailleur, or, for example, a front-mounted indentation for shifting to the larger sprocket, may be sufficient to achieve this.

[0022] With the multiple sprocket arrangement according to the invention, it can be reliably achieved that the chain switches to a sprocket with a smaller diameter essentially only at shift gates. Should the chain nevertheless run in incorrectly, e.g., due to multiple shifting operations in quick succession, the thick tooth(s) of a sprocket with a smaller diameter that has thin and at least one thick tooth can ensure that the chain is immediately resynchronized. For this purpose, the at least one thick tooth of the sprocket with a smaller diameter can prevent a chain inner link from sliding in due to its greater axial extent.

[0023] In the opposite case, i.e., when shifting the chain to an adjacent sprocket with a larger diameter, the sprockets according to the invention, with regard to maintaining the assignment of at least one thick tooth to the outer link plates of the chain and thin teeth to the inner link plates of the chain, are subject to the same conditions as when shifting the chain to an adjacent sprocket with a smaller diameter. In this case, by providing shifting aids in the form of shifting channels with recesses on the teeth on the sprocket with a larger diameter that belong to shifting channels, the chain can be given sufficient space to shift far enough toward the sprocket with a larger diameter in a direction parallel to the rotational axis of the sprockets.According to the invention, a shifting channel is provided along each chain shifting toward the larger-diameter sprocket, as is already known from shifting aids for conventional sprockets. Unlike conventional sprockets, however, the invention also allows for particularly deep recesses where particularly wide chain links, viewed in the axial direction, meet at least one tooth with a thick material thickness.

[0024] In contrast to an arrangement of just one sprocket, as disclosed in document DE 10 2012 023 819 A1, arrangements of multiple sprockets and rear derailleurs or derailleurs necessarily require the use of chain guides on the rear derailleur or derailleur. The chain guide, preventing chain drop due to vibration or chain misalignment, is reliably prevented by the chain roller of the rear derailleur of a bicycle gear system and does not need to be supported by the sprocket geometry. Thickened teeth toward the smaller sprocket are actually disadvantageous, as they can impede smooth and precise shifting to larger sprockets. Furthermore, axial space is very limited, especially in modern sprocket arrangements with a large number of sprockets.

[0025] For this reason, in a further development of the invention, the surfaces of at least some of the, preferably all, teeth of each of the sprockets on a side facing an adjacent sprocket with a smaller diameter can be essentially planar and lie essentially in a common plane, with the exception of the individual teeth which have an indentation or a passage recess. This further development therefore makes it possible to deviate from the principle of completely adapting the tooth thickness to the width of the spaces between the pair of outer chain links or inner chain links. The at least one thick tooth is therefore only thickened on one side, viewed in the axial direction. The chain guide prevents the chain from being displaced too far in the direction of an adjacent sprocket with a larger diameter.

[0026] Accordingly, it is possible to transfer shift gate geometries known from sprockets with teeth of equal thickness to the side of the sprockets according to the invention which faces the adjacent sprocket with a smaller diameter.

[0027] In this further development, the material thickness of thick teeth can be reduced in the direction transverse to the circumferential direction, so that the thick teeth can have a material thickness of 2.2 mm to 3.5 mm, preferably a maximum of 2.45 mm.

[0028] The conditions for maintaining phase assignments must be observed equally for changing the chain to a sprocket with a smaller diameter and for changing the chain to a sprocket with a larger diameter. Compliance with these two conditions on a single sprocket is not necessarily given, as these conditions can contradict each other or be mutually exclusive. Therefore, design measures can be provided to decouple these constraints. Shift gates for changing to the sprocket with a larger diameter can be provided both along an essentially straight chain path, as described above, and along a curved or bent chain path. In the case of a curved path, the teeth at the ends of the shift gate on adjacent sprockets can be rotated towards each other around the sprocket rotation axis.In addition, the distance between the chain pins radially inside the chain rollers, which engage the adjacent sprockets, can be shortened.

[0029] Furthermore, the change to a sprocket with a larger diameter can be realized in the form of a so-called "inner plate step-up" as well as in the form of a so-called "outer plate step-up", whereby the corresponding designations are derived from the type of the last chain link along the shift gate, which bridges a radial distance to the outside.

[0030] The advantages of the multiple sprocket arrangement according to the invention include, but are not limited to, the following: Because the chain rests on the corresponding sprocket toothing in synchronization with the at least one thick tooth and the thin teeth, there is no need to provide appropriate shifting aids for the two engagement variants—that is, for the assignment of an inner link or an outer link to a reference tooth. This reduces the complexity of the arrangement. Shifting to smaller-diameter sprockets under load is improved. This results in fewer variations in shifting operations and a reduced risk of undesirable shifting conditions. Chain vibrations during skew are reduced. So-called "autoshift," i.e., the unintentional switching of the chain to an adjacent sprocket, can be largely avoided. The risk of the chain jumping off the sprocket is also reduced. Wear is reduced because, even with indentations on the teeth, the thick teeth still provide sufficiently large contact surfaces between the chain rollers and the tooth flanks. Especially with a chain drop on the inner link plate, the invention ensures smooth shifting even with large jumps, i.e., with large differences in the number of teeth on adjacent sprockets.

[0031] The multiple sprocket arrangement according to the invention is therefore also suitable for use in electric bicycles (e-bikes) or bicycles with electric drive. To achieve comparatively high acceleration, electric bicycles often have large tooth pitches between adjacent sprockets in a multiple sprocket arrangement. Furthermore, the constant torque of the electric motor exerts large forces on the chain. The resulting requirements for a multiple sprocket arrangement for a rear wheel hub are met by the multiple sprocket arrangement according to the invention, thus achieving smooth and reliable shifting.

[0032] In a further embodiment, it may be expedient not to provide the inventive approach for shifting the chain on sprockets with at least one thick tooth and thin teeth for all sprockets in a multiple sprocket arrangement. This applies in particular to multiple sprocket arrangements in which sprockets with small differences in the number of teeth compared to adjacent sprockets are provided or if, for example, due to the gear steps, sprockets with odd numbers of teeth are also to be used on the larger pinions. In this case, a sprocket with an odd number of teeth and exclusively thin teeth could be arranged between two sprockets with even numbers of teeth, each with at least one tooth sequence with one thick tooth arranged between two thin teeth.

[0033] Therefore, in a further embodiment, the multiple sprocket arrangement can comprise at least one further sprocket having teeth of substantially equal thickness in terms of material thickness, viewed transversely to the circumferential direction. The at least one further sprocket can also be arranged adjacent to the at least one of the plurality of sprockets having at least one thick tooth and thin teeth.

[0034] In this embodiment, conventional sprockets with equally thick teeth and sprockets according to the invention with at least one thick tooth and thin teeth can be provided together in a multiple sprocket arrangement. Consequently, when conventional sprockets are used in a multiple sprocket arrangement with a small difference in the number of teeth between the sprockets, a transition point can be created between a sprocket with a smaller diameter and equally thick teeth below the transition point and a sprocket with at least one thick tooth and thin teeth above the transition point.

[0035] With this design, it must be ensured that the chain, when changing to the first sprocket with at least one thick tooth and thin teeth, the transition sprocket, engages this sprocket in the correct phase assignment. This means that an outer link plate must engage the at least one thick tooth, or an inner link plate must engage a thin tooth. When changing the chain in the opposite direction across the transition point, synchronization plays no significant role.

[0036] When the chain runs onto the transition sprocket, a groove intended for the outer link plate could, with the appropriate geometric design, also accommodate an inner link plate. This unsynchronized run-up of the chain from the smaller-diameter sprocket to the larger-diameter sprocket would then have a negative impact, because synchronization of the chain and the teeth on the larger-diameter sprocket would not be achieved in this situation.

[0037] This means that a recess or indentation intended for an outer or inner plate on the transition sprocket, as part of the shift gate, must always accommodate exactly this corresponding type of plate. Synchronization between the chain and the teeth on the transition sprocket is then inevitable. Accepting the "wrong" or non-corresponding type of plate prevents synchronization. The invention counteracts this.

[0038] In a first counteracting variant, the recess or indentation can be designed in such a way that no "wrong" tab can be accommodated. Alternatively, in a second variant, it can be ensured that the "correct" tab always rests against the indentation from the outset.

[0039] In the first variant, the inclusion of a "wrong" link plate in the recess or indentation can be prevented by providing anti-slip bevels. Accordingly, at least one recess or indentation can have an anti-slip bevel. In conjunction with this, it can be provided that the chain continuously runs off the sprocket with a smaller diameter in alternating positions, for example, by forming an odd number of teeth on the sprocket with a smaller diameter.

[0040] The second variant can consist of providing the chain with an even number of teeth on a sprocket below the transition point and causing the chain to ride up on at least one thick tooth as it runs normally on this sprocket. During this riding up, an inner link plate link can sit on the tip of the thick tooth, resulting in a longer path along the adjacent chain links compared to the path of chain links that normally engage with the teeth and do not ride up. The longer path can cause a switch from a state in which an inner link plate link rests on the thick tooth to a state in which an outer link plate link engages the thick tooth subsequently and on subsequent revolutions.

[0041] The invention will now be described below on the basis of figures of preferred embodiments: Fig. 1a sprocket with thick and thin teeth from the prior art; Fig. 2a sprocket according to Fig. 1 with the roller chain engaged; Fig. 3 a multiple sprocket arrangement with three sprockets shown with schematic diagrams of the chains, which changes between sprockets along shifting paths, viewed from the side of the smallest sprocket; Fig. 4 a multiple sprocket arrangement according to Fig. 3 , viewed from the side of the largest sprocket; Fig. 5 a sprocket of a multiple sprocket arrangement with a bevelled tooth to assist in changing the chain to the next smaller sprocket in a conventional multiple sprocket arrangement; Fig. 6 a section of the multiple sprocket arrangement according to Fig. 4, viewed from the side of the largest sprocket, for changing the chain to the smaller sprocket; Fig. 7Recesses or indentations along the shift gate for changing the chain to the smaller sprocket according to Fig. 6 , in which an inner plate passage takes place; Fig. 8Recesses or impressions along the shift gate for a change to the smaller chain wheel in a modified embodiment, in which, as in Fig. 7 an inner plate passage in conjunction with an inner plate descent; Fig.9 a schematic representation of the switching to a larger sprocket from the multiple sprocket arrangement according to Fig. 4 , viewed from the side of the smaller sprocket, where an inner plate passage takes place in conjunction with an inner plate rise; Fig. 10 Details of the shift gate for switching to a larger sprocket according to Fig. 9; Fig. 11 a representation of the sprocket and chain during a switching process with outer plate rise in combination with an inner plate passage on a sprocket of a conventional multiple sprocket arrangement; Fig. 12 a schematic representation of the switching to a larger sprocket according to Fig. 4 , viewed from the side of the smaller sprocket, where an outer plate ascent with subsequent inner plate passage takes place; Fig. 13 Details of the shift gate for switching to a larger sprocket according to Fig. 12; Fig. 14 shows a sprocket of a multiple sprocket arrangement with an impression or shift gate in a conventional multiple sprocket arrangement, in which either an inner plate rise in combination with an inner plate passage or an outer plate rise with subsequent inner plate passage takes place; and Figures 15 and 16 show an impression on a sprocket of a conventional multiple sprocket arrangement, in which the engagement of an outer plate link on a tooth suitable for the engagement of this outer plate link is prevented.

[0042] In the following, the terms "thick" and "thin" also refer to the material thickness of teeth viewed in a direction transverse to the circumferential direction of a sprocket. Furthermore, the terms "large" and "small" in relation to individual sprockets refer to the size of the diameter and the number of teeth of the respective sprockets.

[0043] The Figure 1shows a prior art sprocket with thick teeth 21 and thin teeth 22. This is a sprocket for a bicycle crank.

[0044] In Figure 2 It can be seen how the thick sprocket teeth 21 and the thin sprocket teeth 22 engage with the chain 5 in a synchronized manner with the outer link plates 7 and the inner link plates 6 of the chain 5. The tooth shape follows the principle of adapting the tooth thickness to the width of the spaces between the pair of outer link plates and inner link plates.

[0045] The chain 5 is designed as a roller chain and has outer link plates 7 and inner link plates 6, which are rotatably connected to one another at chain joints 8. On a chain joint 8, pairs of outer links 71, pairs of inner links 61, and chain rollers 9 are arranged on a chain pin 81. The chain pin 81 is firmly pressed into the outer links 71 and / or riveted to them. The inner links 61 have collars on which the chain roller 9 is rotatably mounted. The inner links 61 are rotatably movable relative to the chain pin 81.

[0046] Figure 3shows a sectional view through a multiple sprocket arrangement 1 according to the present invention, viewed from the side of the smaller sprockets, in which the three largest sprockets 12, 13 and 14 are still visible. The smaller sprocket 12 and the middle sprocket 13 belong to a one-piece conical support structure with openings, in which webs 11 running in the radial direction and in a direction parallel to the axis of rotation A establish the connection between the smaller sprocket 12 and the middle sprocket 13. The larger sprocket 14 is designed as a final sprocket and is supported by a support disk (not shown) radially inwardly against a driver (not shown) and against the hub axle (likewise not shown).

[0047] In the drive case, the multiple sprocket arrangement 1 rotates in the direction of rotation D.

[0048] On the multiple sprocket arrangement 1, several chain pieces 51 of a chain are arranged schematically to illustrate the different states that occur when the chain 5 switches from one of the sprockets 12, 13, 14 to an adjacent sprocket. The inner links 61 are only schematically illustrated by a line between adjacent chain links. Partial outlines of the outer links 71 are shown. Furthermore, it is not shown whether teeth are located inside or outside the space between a pair of outer links 71 or a pair of inner links 61. Rather, the outlines of the teeth 2 and the outer links 71 are shown schematically with equal importance.

[0049] The teeth 2 on the sprockets correspond to either thick teeth 21 or thin teeth 22, with the thick teeth 21 being marked by circles in the tooth body, which are not geometric elements on the teeth 2, but in the graphic representation merely serve to distinguish them from the thin teeth 22. This representation is necessary because the thick teeth 21 extend only in the axial direction outside the plane of the drawing and are therefore not visible in the front view.

[0050] The chain pieces 51 arranged between the sprockets 12, 13 and 14 are either outgoing chain pieces that extend from the sprocket 14 with a larger diameter to the sprocket 13 with a smaller diameter, or they are incoming chain pieces that extend from the sprocket 13 with a smaller diameter to the sprocket 14 with a larger diameter.

[0051] Free chain sections 54 consist of a subset of the chain links 6, 7 of the outgoing chain sections, or the incoming chain sections. The chain joints inside free chain sections 54 are not engaged with teeth 2 of the sprockets 12, 13, 14, whereby "engagement" between sprocket teeth 2 and chain links is characterized by the respective sprocket tooth 2 having entered the space between the link plates 61, 71 of a respective link plate pair, and by the chain roller 9 being located at least sufficiently far radially inward in the gap between the sprocket teeth 2. At the ends of free chain sections 54, there is a knuckle joint 55 assigned to the larger sprocket 13, 14, and a tangential joint 56 assigned to the smaller sprocket 12, 13.The chain pin 81 on the kinked joint 55 is located substantially centrally between two teeth 2 on the sprocket 14, 13 with the larger diameter and connects chain links 6, 7 bent relative to one another. The chain pin on a tangential joint 56 is the first chain joint 8, the chain roller of which is located substantially centrally between two teeth 2 on the sprocket 13, 12 with the smaller diameter, with the chain running tangentially onto the smaller sprocket 12, 13 there.

[0052] Figure 4 shows the multiple sprocket arrangement according to Figure 3 , but viewed from the side of the largest sprocket 14. Further radially inward components of the sprockets, which are not essential for the switching processes, are not shown.

[0053] When shifting to a larger sprocket, an outer link plate shift occurs when the tooth of the larger pinion, on whose leading edge the end of the free chain piece 54 rests, receives an outer link plate. If this tooth is passed by an inner link plate, the shift is an inner link plate shift. The free chain pieces in the Figure 3 and 4 are marked accordingly.

[0054] Figure 5 A sprocket of a prior art multiple sprocket arrangement is shown. A beveled passage tooth 26 provides space for an inner link plate link to pass the passage tooth 26 during an inner link plate passage.

[0055] In Figure 6An inner link plate descent (IAb) of a sprocket according to the invention is shown, viewed from the side of the largest sprocket 14. The inner link plate 61 is the first chain link to leave the pinion. Even if the chain only bends at the outer link plate (because it is held by the edge 37), the inner link plate 61 no longer engages the pinion.

[0056] It should be noted that in the Figure 4 and 6It is shown that the thick teeth 21 of the largest sprocket 14 each have a load-transmitting tooth flank (leading in the direction of rotation D) 91, which is formed with full material thickness. However, the area near the trailing tooth flank (rear flank) 92 of these thick teeth 21 facing away from it is stepped in terms of material thickness and has a recess 93 provided at least in sections along its contour, so that a stepped or shoulder-shaped tooth profile results when viewed in the radially inward direction. A tangential section through such a tooth 21 results in an L-profile in plan view, taking into account that the back of the sprocket 14 is essentially planar (see Fig. 7 ).

[0057] In Figure 7shows a possible embodiment for the recesses or impressions 39 along the shift gate for a change to the smaller chain wheel when an inner plate descent according to Figure 6 The inner link plate passes tooth 22, which is provided with the necessary space by the embossing on the front. The recess or indentation 39 provides space for the outer link plate.

[0058] In Figure 8 the recesses or impressions 39 along the shift gate are designed for a different design from the design according to Figure 7 modified change to the smaller sprocket, in which an inner plate passage takes place at the passage tooth 22. It can be seen that the impression 39 for an outer plate runs more steeply radially inwards than in the Figure 7 This is the case. Compared to Figure 7This allows the chain to bend earlier, resulting in slightly more chain length for entry into the adjacent smaller pinion. This allows the smaller pinion to be rotated in the opposite direction to the drive direction of the larger pinion.

[0059] The radial position of the support edge 37 at the indentation 39 determines how far an outer plate received in this indentation 39 can be displaced radially inwards.

[0060] Figure 9 shows schematically the switching to a larger sprocket on the multiple sprocket arrangement according to the Figure 3 and 4 , viewed from the side of the smaller sprocket, with tooth 22, on whose leading edge the chain rests, receiving an outer link plate.

[0061] Figure 10 shows details of the shift gate for a shifting process according to Figure 9, viewed from the side of the smaller sprocket. It is clear how far a ramp 36 can extend to provide space for the outer link plate and to support the outer link plate radially inward by means of the support edge 37. The edge 37 extends over a double recess or indentation for the outer and inner link plates. The segment with the reference numeral 37 shows the inner link plate. However, the essential support function is primarily realized by the leading edge on tooth 21.

[0062] If the sprockets 12, 13 are positioned starting from the Figure 3 and 4shown phase assignment are rotated in their angular position relative to each other, so that the tangential joint 56 and the articulated joint 55 move towards each other according to the angular offset, then the articulated joint 55 changes its position radially outwards. This results in a bent or curved course of the free chain piece 54, which can be further reinforced by a corresponding positioning of the impression 39. The radial position of the support edge 37 must also be determined accordingly. The extent of the movement towards each other in the arrangement of the two chain wheels 12, 13 is limited by the fact that the impression does not extend to the load flank 38 ( Fig. 7 ) of the deflector tooth 24 ( Fig. 5 ) should be sufficient so that the deflector tooth 24 has the largest possible surface available for contact between the load flank 38 and the chain roller 9. A corresponding possible design is shown in Figure 10 shown.

[0063] Figure 11is a representation of an impression for the outer plate rise in combination with an inner plate passage on a sprocket of a conventional multiple sprocket arrangement.

[0064] Figure 12 shows schematically the switching to a larger sprocket 14 in the multiple sprocket arrangement according to the Figure 3 and 4 , viewed from the side of the smaller chain wheel 13. The thin tooth 22, on whose leading edge the chain 5 rests, is suitable for receiving an inner plate 61, whereby the inner plate 61 does not engage during ascent, but rests against the impression. Figure 13 shows the details of the shift gate for switching to a larger sprocket 14 of the multiple sprocket arrangement, i.e. during a switching process according to Figure 12 .

[0065] In Figure 14A sprocket of a conventional multiple sprocket arrangement with an indentation 39 is shown, in which, in the first possible engagement case, an outer link plate ascends followed by an inner link plate passage occurs. In this case, the indentation 39 receives the outer link plate of an outer link plate link.

[0066] The transition sprocket can be designed according to Figure 10 and / or 12 may be used if appropriate adjustments are made to the existing thick and thin teeth and other conditions are observed.

[0067] In Figure 15 An indentation on a sprocket of a multiple sprocket arrangement for the inner link plate ascent followed by the outer link plate passage is shown. The at least one tooth thickened in the direction perpendicular to the plane of the drawing is not shown in detail.

[0068] Figure 16illustrates a chain assignment according to an inner link ascending. The following outer link 7 does not engage, but is rejected, resulting in the passage of this outer link 7 and also the following inner link 6. This prevents the engagement of an outer link link with a tooth that is actually suitable for engagement of this outer link link.

[0069] With appropriate adjustments, this design approach can be used for a shift gate and a catch tooth on a transition sprocket with an outer plate rise with subsequent inner plate passage according to Figure 14 be used.

[0070] The present invention shows how individual sprockets of a multiple sprocket arrangement can be designed so that, on the one hand, a shift of the chain during a gear change through corresponding shift gates can be carried out reliably and quickly both from a smaller sprocket to a larger sprocket and in the opposite direction from a larger sprocket to a smaller sprocket, and it is also ensured that the chain is safely guided on the sprocket.

Claims

1. Multi-sprocket arrangement (1) for a rear wheel hub of a bicycle, which multi-sprocket arrangement comprises a multiplicity of sprockets (12, 13, 14) of different diameters, wherein at least one of the sprockets (12, 13, 14) has in each case a plurality (Z) of teeth (2), which can be brought into engagement with a chain (5) composed of inner link elements (6) and outer link elements (7), wherein, on the circumference of said sprocket (12, 13, 14), as viewed in a circumferential direction, at least one sequence of teeth (21, 22) is provided, and wherein, on said sprocket, at least one impression (39) and / or a passage recess (32) are provided which form at least one gearshift channel and permit a changeover of the chain (5) between two adjacent sprockets (12, 13, 14), wherein the impression (39) and / or the passage recess (32) on at least one of the teeth (2) of said sprocket (13, 14) of relatively large diameter, said tooth forming a passage tooth, is provided for the passage of an inner link (61) of the chain (5) in order for the chain (5) to descend onto an adjacent sprocket (12, 13) of relatively small diameter, characterized in that, in the sequence of teeth, with regard to their material thickness, a thin tooth is followed directly by a thick tooth which is in turn followed directly by a thin tooth.

2. Multi-sprocket arrangement (1) according to Claim 1, wherein the sequence of teeth composed of a thin tooth (22) followed by a thick tooth (21) followed by a thin tooth (22) is repeated two times, several times or continuously in the circumferential direction of the at least one sprocket.

3. Multi-sprocket arrangement (1) according to either of the preceding claims, wherein, in each case, the surfaces of at least some, preferably all, of the teeth (2) of at least one of the sprockets (12, 13, 14) on a side pointing towards an adjacent sprocket (12, 13, 14) of relatively small diameter lie substantially in a common plane, wherein the individual teeth (21, 22) which have an impression (39) or a passage recess (32) are set back in relation to said plane.

4. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein at least one sprocket (12, 13, 14) of relatively small diameter is oriented, in terms of phase, with respect to an adjacent sprocket (12, 13, 14) of relatively large diameter such that, during a changeover of the chain (5) from the sprocket of relatively large diameter to the sprocket of relatively small diameter, synchronicity between the teeth (21, 22) of the sprocket (12, 13, 14) of relatively small diameter and respectively associated chain elements of the chain (5) is realized.

5. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein at least one sprocket (12, 13, 14) of relatively small diameter is oriented, in terms of phase, with respect to an adjacent sprocket (12, 13, 14) of relatively large diameter such that, during a changeover of the chain (5) from the sprocket of relatively small diameter to the sprocket of relatively large diameter, synchronicity between the teeth (21, 22) of the sprocket (12, 13, 14) of relatively large diameter and respectively associated chain elements of the chain (5) is realized.

6. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein the multi-sprocket arrangement (1) comprises at least one further sprocket which, as viewed in a direction perpendicular to the circumferential direction, has teeth of substantially identical thickness with regard to material thickness, and which is arranged adjacent to the at least one sprocket with thick and thin teeth.

7. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein at least one transition pinion is provided which does not comprise a relatively thick tooth.

8. Multi-sprocket arrangement (1) according to Claim 6, wherein the at least one transition pinion has an odd number of teeth.

9. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein the at least one sprocket (12, 13, 14) of relatively small diameter has, as viewed in a direction perpendicular to the circumferential direction, thick teeth (21) and thin teeth (22) with regard to their material thickness.

10. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein at least one of the teeth (2) has a support edge (37) which is designed to support an inner link (61) or an outer link (71) of the chain (5) in a radially inward direction with respect to the axis of rotation of the associated sprocket (12, 13, 14).

11. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein the at least one impression (39) has a slide-off bevel which prevents an unintended link of the chain (5) from being received therein.

12. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein the teeth (21, 22) of adjacent sprockets (12, 13, 14) at the ends of the gearshift channel are turned towards one another about the axis of rotation of the sprockets (12, 13, 14).

13. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein a pinion with a thick tooth, which is arranged adjacent to a transition pinion of relatively small diameter and without a thick tooth, has gearshift impressions or passage recesses which are suitable for allowing an outer link to ascend, and preventing an inner link from ascending, at a defined position.

14. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein a pinion with a thick tooth, which is arranged adjacent to a transition pinion of small diameter and without a thick tooth, has gearshift impressions or passage recesses which are suitable for allowing an inner link to ascend, and preventing an outer link from ascending, at a defined position.

15. Multi-sprocket arrangement (1) according to one of the preceding claims, wherein, on at least one sprocket of relatively small diameter, at least one thick tooth with regard to its material thickness is provided, which is designed in such a way that said tooth, owing to its relatively large axial extent due to material thickness, prevents a chain inner link from sliding in.