Rear wheel hub for bicycles with freewheel and reduced noise level

Abstract

Rear wheel hub (1) for bicycles with a freewheel based on the pawl principle, wherein an external toothed body (5) is rotationally fixed in the hub body (2) of the rear wheel hub (1), the external toothed body having radially inwardly directed teeth (6) which essentially consist of long and short tooth flanks (7, 8) uniformly arranged one behind the other around the circumference, periodically repeating, which form sliding surfaces (30) for a pawl (10) sliding over them, which is arranged on an internal toothed body (12) and which, in the freewheel state, slides along at least the long tooth flanks (7) of the teeth (6, 6a) of the external toothed body (5), wherein at least one damping element (20, 50) is arranged in the clearance (9) between the teeth (6, 6a) of the external toothed body (5) and the pawl (10), which at least partially covers the long The tooth flanks (7) of the external tooth body (5) project in a radial direction, characterized in thatthat the damping element is designed as a contour disc (20) which has essentially the same toothing (24) as the external toothing body (5), wherein the toothing (24) of the contour disc (20) is designed such that the pawl (10) slides along the tooth flanks (21, 22) of the noise-damping contour disc (20) in the free-running direction (17).

Description

[0001] The bicycle hub is the center of a wheel. On a bicycle wheel, it rotates around an axle that is firmly clamped in the dropouts.

[0002] The essential components of a bicycle hub are the axle, bearings, and hub shell. Depending on the design, the hub may be equipped with additional elements such as a brake or freewheel. The spokes are attached to the hub shell.

[0003] A freewheel (also called an overrunning clutch) is a clutch that only acts in one direction of rotation. Freewheels can be equipped with the following components: Clamping rollers Clamping body Locking pawls Claw rings coiling spring The pawl freewheels click when in freewheel mode, while the other freewheels operate silently.

[0004] The present invention deals with the reduction of noise from noise-generating freewheels, in particular freewheels with pawls and toothed discs.

[0005] The first freewheel system refers to a so-called pawl freewheel, which consists of an external toothed body being fixed in the hub body of a rear wheel hub in a rotationally fixed manner, which has a radially inward-directed toothing that essentially consists of long and short tooth flanks that repeat periodically one after the other.

[0006] The long and short tooth flanks of the external gear body's teeth form sliding surfaces for a pawl sliding in a free space above them, which, in particular, slides along the long tooth flank of the external gear body's teeth with a sliding surface located radially outside with respect to the axis of rotation when the freewheel is engaged.

[0007] If, however, the rotation direction is reversed, the end face of the pawl engages with the short tooth flank of the external tooth body and creates a rotationally fixed connection between an internal tooth body and the external tooth body.

[0008] In such a well-known pawl-type freewheel system, the noise generated during freewheeling has proven to be a disadvantage.

[0009] The noise is generated because the spring-loaded, pivoting pawl strikes from the raised short tooth flank into a free space towards the long tooth flank with each tooth stroke, and the sliding surface of the pawl on the long tooth flank produces an unpleasant clicking noise.

[0010] DE 10 2014 013 005 A1 describes a rear wheel hub for bicycles with a freewheel based on the pawl principle. An external toothed body is fixedly arranged within the hub body of the rear wheel hub, featuring radially inward-facing teeth. These teeth essentially consist of long and short tooth flanks arranged uniformly around the circumference, repeating periodically, which serve as sliding surfaces for a pawl sliding over them. The pawl is arranged on an internal toothed body and, in the freewheel state, slides at least along the long tooth flanks of the teeth on the external toothed body.

[0011] The damping element, which moves together with the pawl, at least partially dampens the impact on the long tooth flanks, thereby also reducing noise. However, this introduces an additional component subject to wear. Furthermore, there is a risk of sudden blockage due to jamming or snagging between the sliding and impacting components.

[0012] CH 255 864 A describes a freewheel based on the pawl principle, in which an external toothed body is mounted in a rotationally fixed manner. This body has radially inward-facing teeth, which essentially consist of long and short tooth flanks arranged uniformly one after the other around the circumference and repeating periodically. These tooth flanks form sliding surfaces for a pawl mounted on an internal toothed body, which slides over them. In the freewheeling state, the pawl slides at least along the long tooth flanks of the external toothed body. The ends of the rocker-shaped pawl strike against plate-shaped damping elements on the inner or outer body.

[0013] Due to the rocker-like design of the pawl, the entire assembly is very large and heavy, making it unsuitable for use in compact bicycle rear wheel hubs. Furthermore, the CH 255 864 A was originally designed for rack-and-pinion vehicles, where neither a compact design nor low weight is crucial.

[0014] In a second configuration according to the prior art, freewheel systems are also known which consist of two axially opposed spur gears, wherein a first spur gear body is located at the bottom and has an axially upward-facing toothing that can either engage with an associated toothing of the upper spur gear body or operate in freewheel mode. These freewheels are described as toothed disc freewheels in the prior art.

[0015] Even with such a well-known spur gear design with axially overlapping spur gear discs, an unpleasant clicking noise occurs when the freewheel is engaged and when the teeth of the upper and lower spur gear body slide along.

[0016] The invention is therefore based on the objective of achieving a reduced noise level in freewheel systems for rear wheel hubs of bicycles.

[0017] To solve the problem posed, the invention is characterized by the technical teaching of independent patent claims 1 and 8.

[0018] A preferred feature of the invention is therefore a rear wheel hub for bicycles with a freewheel based on the pawl principle, wherein an external toothed body is rotationally fixed in the hub body of the rear wheel hub, which has radially inwardly directed teeth that essentially consist of long and short tooth flanks that follow each other uniformly around the circumference and repeat periodically, forming sliding surfaces for a pawl sliding over them, which is arranged on an internal toothed body and which, in the freewheel state, slides along at least the long tooth flanks of the teeth of the external toothed body, wherein at least one damping element is arranged in the space between the teeth of the external toothed body and the pawl, which projects at least partially beyond the long tooth flanks of the external toothed body in a radial direction.

[0019] With regard to the technical doctrine defined above, which assumes a hub-fixed internal gear body that can be coupled to a spoke-fixed external gear body via at least one pawl, the kinematic converse also applies: a spoke-fixed internal gear body can be coupled to a hub-fixed external gear body. However, for the sake of simplicity, the first embodiment will be used.

[0020] A preferred feature of the invention in a first embodiment is therefore that at least one noise-damping damping element, preferably made of an elastomeric plastic material, is arranged in the free space between the toothing of the external toothing body and the pawl.

[0021] In a preferred first embodiment, the damping element consists of a contour disc that is at least partially toothed, and in a second embodiment, of a damping ring, which is preferably designed as an O-ring.

[0022] Instead of the O-ring design, which has a round profile, other profiles can also be used, such as a ring with a rectangular or square profile.

[0023] In the case of the first embodiment relating to the contour disc, it is preferred if the contour disc has essentially the same toothing as the external toothing body, wherein the toothing of the contour disc is designed such that, in the freewheeling direction, the pawl strikes the tooth flanks of the noise-damping contour disc and, over a certain damping distance, no longer slides along the long tooth flank of the external toothing body, but rather on the damping surfaces of the contour disc.

[0024] Only in the locked position does the pawl engage with the short tooth flank of the external tooth body.

[0025] This means that in freewheel mode, the pawl no longer strikes the long tooth flank of the external tooth body, but rather the noise-dampening long tooth flank of the contour disc, which is approximately triangular in the circumferential direction and extends beyond the long tooth flank of the external tooth body by at least part of its length.

[0026] The tooth height of the contour disc's toothing, extending in a radial direction, is therefore higher – at least over part of the length of the long tooth flank – than the tooth height of the external toothing body.

[0027] This achieves the advantage that, in freewheeling, it is avoided that the toothing of the external toothing body comes into direct contact with the sliding surface of the pawl, because in this case the pawl only slides along the approximately similar toothing of a noise-reducing damping body.

[0028] The damping element is preferably designed as a contour disc or as a damping ring.

[0029] This achieves a reduction in noise, because the noticeable clicking sound when the free end of the pawl strikes down from the short tooth flank of the external gear body onto the long tooth flank is now avoided by the damping element being located precisely in this area, so that the pawl strikes either the radially projecting long tooth flank of the contour disc or the surface of the damping ring, thus avoiding direct impact on the teeth of the external gear body.

[0030] In the second embodiment - which is formulated as independent subsidiary claim 8 - the same noise-damping design is provided for a spur gear toothing, in which it is provided that a damping element is inserted in the space between an upper and a lower spur gear body, which can be coupled to each other in the axial direction, which is preferably designed as a noise-damping, at least partially toothed contour disc or as an untoothed damping ring.

[0031] In the case of using a contour disc, it is preferred if the toothing of the contour disc is approximately the same as the toothing of the two corresponding face gear bodies.

[0032] For the sake of simplicity, the terms "upper" and "lower" face gear body are used, but they are interchangeable.

[0033] However, the toothing of the contour disc has such a toothing that its toothing in the transition from the short tooth flank to the long tooth flank - over a certain damping distance - has an axial projection which ensures that the toothing of the lower face gear body slides along the toothing of the noise-dampening contour disc in the freewheel position and only in the opposite direction do the two toothings of the face gear bodies engage.

[0034] This means that the axial tooth height of the contour disc's teeth is greater than the tooth height of the lower face gear body. This also applies to the outer diameter of an untoothed damping ring, which is preferably designed as an O-ring.

[0035] In a preferred embodiment for both versions, the contour disc preferably consists of a noise-dampening material, such as nitrile rubber or a plastic material, for example, PTFE or another suitable elastomeric and sliding material. It can also be a noise-dampening metallic material, such as a sintered metal, a metal-plastic composite, a metal-rubber composite, or the like. The key feature is that at least the long toothed flanks of the contour disc are made of the aforementioned noise-dampening material and are preferably elastic or elastomeric in order to absorb the kinetic energy of the pawl's impact in a noise-dampening manner.

[0036] If an O-ring is used, it is preferably made of a material such as various types of rubber, perfluoroelastomer (FFKM or FFPM), polyethylene (PE), or polytetrafluoroethylene (PTFE). This also applies to the material of the contour washer.

[0037] It is preferred that the short tooth flank of the contour disc is approximately flush with the short tooth flank of the external tooth body to ensure that in the locked position - i.e., in contrast to the freewheel - the front face of the pawl also bears load against the short tooth flank of the external tooth body and transmits the full torque, whereby in this case the toothing of the contour disc does not contribute to load transmission.

[0038] The same applies to the second embodiment defined in subsidiary claim 8, because in the case of spur gear toothing with axially opposing spur gear discs, it is ensured that the axial toothing of the respective gear body does not rest on the toothing of the opposing spur gear body, but on an intermediate damping body, which can be designed as a contour disc with at least partial toothing or as an untoothed damping ring.

[0039] The contour disc ensures that the toothing of the upper face gear body runs along the axially projecting long tooth flank on the contour disc and only in the locked case do the short tooth flanks of the two gear bodies engage with each other in a load-transmitting manner, without stressing the toothing of the contour disc.

[0040] This also provides that the plane of the short tooth flank of the contour disc is approximately flush with the plane of the short tooth flank of the face gear body, in order to achieve full torque transmission via the metallic, interlocking tooth flanks of the upper and lower face gear body in the case of locking.

[0041] In a third preferred embodiment, it is provided that the sliding surface of the pawl, which slides along the long tooth flank on the outer tooth body, is provided with a noise-damping sliding element and / or a noise-damping sliding surface.

[0042] In a preferred first embodiment, such a sliding body may be designed in a strip-like form and consist of a nitrile rubber, a PTFE material or another highly lubricious elastomeric material, such as silicone rubber or other suitable plastics or metal sintered bodies.

[0043] Such a sliding element can be provided in the form of a sliding track, a sliding strip or a sliding coating on the sliding surface of the pawl, and it is preferred that the sliding element is received in an associated undercut bearing groove in order to achieve a reliable attachment to the sliding surface of the pawl.

[0044] In another embodiment, it may also be provided that the sliding surface of the locking pawl is coated entirely with a noise-reducing plastic or a metal sintered material.

[0045] It may also be provided that a noise-dampening material is glued, sputtered, foamed or otherwise securely attached to the sliding surface of the pawl.

[0046] Similarly, in a further development of the invention, it may also be provided that at least the long tooth flanks of a face gear body are also provided with the above-mentioned noise-reducing means (noise-reducing strips, plates, coatings and the like).

[0047] The subject matter of the present invention is not only derived from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

[0048] All information and features disclosed in the documents, including the abstract, and in particular the spatial configuration shown in the drawings, could be claimed as essential to the invention, insofar as they are novel individually or in combination compared to the prior art. The use of the terms "essential," "inventive," or "essential to the invention" is subjective and does not imply that the features so designated must necessarily be part of one or more patent claims.

[0049] The invention is explained in more detail below with reference to drawings illustrating only one embodiment. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0050] They show: Fig. 1: Side sectional view of a freewheel of a rear wheel hub according to the state of the art using the pawl system Fig. 2: a spatial representation of an external gear body with a contour disk according to the invention in a first embodiment Fig. 3: a contour disc according Fig. 2 in solo presentation Fig. 4a: a second embodiment of installing a contour disc in an external gear body Fig. 4b: Cut along line VV in Fig. 4a Fig. 5: the same representation as Fig. 4a from a different perspective Fig. 6: the enlarged representation of the arrangement according to Fig. 4a and Fig. 4b in the locked position Fig. 7: the same representation as Fig. 6 in freewheel position Fig. 8: An enlarged perspective view of the pawl in the freewheel position according to Fig. 7 Fig. 9: another embodiment of the toothing of an external toothing body with noise-reducing measures that do not rely on a contour disc Fig. 10: a second embodiment of a freewheel system based on the spur gear principle, wherein a perspective top view of a spur gear toothing part is shown. Fig. 11: the perspective representation of a contour disk, as used in connection with Fig. 10 is used Fig. 12: a perspective view of the spur gear toothing part Fig. 13: Section according to line XIII-XIII in Fig. 12 Fig. 14: another embodiment compared to the Fig. 12 with a different installation situation of the contour disc Fig. 15: another embodiment of a spur gear toothing part with a different embodiment of a contour disc Fig. 16: A third embodiment for a noise-reducing measure by suitable coating of the sliding surface of the pawl in perspective view Fig. 17: a version similar to the Fig. 2, in which the contour disc is replaced by a damping ring, according to a section through the illustration in Fig. 18. Fig. 18: Top view of the arrangement according to Fig. 17

[0051] The Fig. Figure 1 shows a prior art rear wheel hub design, wherein the rear wheel hub consists of an outer hub body 2, on the outer circumference of which spoke receptacles 3 are arranged evenly distributed, to which the ends of spokes attack, the spokes being connected with their opposite ends to the rim ring.

[0052] The hub body 2 is connected via a separation joint 4 in a rotationally fixed manner to an external toothed body 5, which has a radially internal toothing 6 consisting of uniformly alternating long tooth flanks 7 and adjoining short tooth flanks 8.

[0053] The toothing 6, consisting of the tooth flanks 7, 8, forms a radially internal clearance 9 in which a pawl 10 runs, which is pivotably and spring-loaded arranged on an internal toothing body 12.

[0054] In the blocking position - which is in Fig. As shown in Figure 1, the pawl 10 engages with its front face on the short tooth flank 7 of the external tooth body 5 in order to enable a rotationally fixed connection between the external tooth body 5 and the internal tooth body 12 when rotating in the direction of arrow 18 (locking direction).

[0055] If, on the other hand, the outer gear body 5 rotates in the direction of arrow 17 relative to the inner gear body 12, then the freewheel is engaged, and the sliding surface 27 (see Fig. 6 and Fig. 7) the pawl 10 slides along the long tooth flanks 7 of the external toothing body 5 and leads to the - which should be avoided if possible - clicking noise, which is to be eliminated by the measures according to the invention.

[0056] The outer ring 13 of a ball bearing 14 rests against the inner toothed body 12, the inner ring 15 of which is non-rotatably connected to the hub axle 16.

[0057] According to Fig. 2 is a first embodiment of a contour disc 20 installed in the space between two mutually parallel and aligned toothings 6 and 6a of the external gear body 5, wherein it is preferably that the long tooth flank 21 of the contour disc 20, which consists of a noise-damping material, radially extends beyond the long tooth flanks 7 of the two toothings 6 and 6a over a certain length of a damping section 51, so that the pawl 10, shown only in dashed lines, which slides in the direction of arrow 17 over the two sliding surfaces of the toothing flanks 7 and 7a, no longer slides along these toothing flanks 7, 7a, but rather along a long noise-damped tooth flank 21 of the contour disc 20. The long tooth flank 21 can be the same length as or shorter than the length of the toothing flank 7 of the external gear body. be.Accordingly, the damping section 51 of the contour disc 20 formed thereby extends over the entire length of the long tooth flank 7 or only over a part of this length.

[0058] Since the contour disc 20 is made of a noise-dampening, preferably elastomeric and / or elastic material, the clicking noise is significantly reduced, because the free spring-loaded end of the pawl 10 no longer strikes the long tooth flanks 7, 7a of the external tooth body 5, but rather the long noise-dampened tooth flank 21 of the contour disc 20.

[0059] This is shown in dashed lines in Fig. Figure 10 shows that in the locking position, when the end face of the pawl enters the locking position, the short tooth flank 22 of the contour disc 20 is approximately flush with the short tooth flanks 8, 8a of the toothing 6 or is even recessed behind them, so that a high-load torque transmission is possible via the tooth flanks 8, 8a of the external toothing body 5, because the short tooth flank 22 of the contour disc 20 no longer plays a role in this torque transmission.

[0060] The Fig. Figure 3 schematically shows such a contour disc 20 in a top view, which essentially consists of a toothing 24 that can be congruent and aligned with the toothing 6 of the external gear body 5, but the long tooth flank 21 forms a projection 23 above the schematically shown tooth flank 7 of the toothing 6 of the external gear body 5, so that it is ensured that the free spring-loaded end of the pawl 10 strikes this projecting long tooth flank 21 of the contour disc 20 and slides there over a certain length of a damping section 51, thereby greatly reducing the undesirable clicking noise.

[0061] The short tooth flanks 22 of the contour disc 20 should then be essentially identical to the short tooth flanks 8 of the toothing 6, so as not to impede the high-load torque transmission on the external tooth body via the pawl.

[0062] It is in Fig. 4b further shows that the contour disc 20 has radially projecting positioning pins 26 on its outer circumference, which engage in associated positioning bores 25 of a Fig. 4b engage the external gear body 5 in order to connect the contour disc 20 to the external gear body 5 in a positionally secure and rotationally fixed manner.

[0063] The Fig. 4a and Fig. Figure 4b shows a different installation situation in which it is evident that the contour disc 20 is not necessarily arranged in the central area between two aligned teeth 6 and 6a of an external toothing body 5, but is merely arranged on an end face of the toothing 6, as shown in the Fig. 4a and Fig. 4b is shown.

[0064] Here too, the same principle applies: the long tooth flank 21 of the contour disc projects beyond the long tooth flank 7 of the toothing by a projection 23, ensuring that the pawl 10, when sliding along the tooth flank 7, does not slide along it, but rather on the long noise-dampened tooth flank 21 of the contour disc 20.

[0065] This is on average in Fig. Figure 5 shows the pawl 10 sliding along the long tooth flank 7 of the toothing 6 of the external tooth body 5 without engaging with this toothing 6. The pawl strikes the projection 23 of the contour disc 20 in the area of ​​the long tooth flank 21 and slides along it.

[0066] The toothing 6, 6a of the external toothing body 5 therefore preferably does not come into contact with the pawl 10. This strikes the long noise-damped tooth flank 21 of the toothing of the contour disc 20 and slides along it over a certain circumferential distance (damping distance 51).

[0067] The Fig. 6 and Fig. Figure 7 shows the different situations of the pawl freewheel, where the Fig. 6 shows the locking position, while the Fig. 7 shows the freewheel position.

[0068] In comparison between Fig. 6 and Fig. Figure 7 clearly shows that the end face of the pawl 10 is in full engagement with the short tooth flank 8 of the toothing 6 in the locking direction, while in the freewheel position after Fig. 7 The sliding surface 27 of the pawl 10 slides along the projection 23 of the tooth flank 21 of the contour disc 20 and, upon impact, i.e., upon overcoming the short tooth flank 22, 8 now impacts the long tooth flank 21 of the contour disc 20 in a noise-dampening manner and slides along this flank along a damping section 51 formed thereby. The length of the damping section can be equal to or shorter than the length of the long tooth flank 7 of the external gear body 5.

[0069] The Fig. 8 shows the same situation as Fig. Figure 7 in the perspective view shows that the sliding surface 27 of the pawl 10 can also be provided with additional noise-dampening properties. As an example, it is shown that a sliding element 47 is arranged in a bearing groove 48, which protrudes beyond the sliding surface 27 of the pawl 10, so that the pawl 10 engages with the long tooth flank 21 of the contour disc 20 only with its sliding element, thus providing further noise reduction.

[0070] In another version, based on the Fig. As shown in Figure 16, it may be possible to eliminate the noise-reducing measures by adding a contour disc and to provide only the pawl with noise-reducing properties on its own, for example by coating, bonding, or molding the sliding surface with noise-reducing material or by fitting it with a sliding element 47, which forms the sliding surface 27 of the pawl 10 in a suitably secured manner. The use of an additional damping element 20, 40, 50 may be provided or omitted.

[0071] The Fig. Figure 9 shows, as a further measure for noise reduction, a complete coating 28 of a noise-insulated sliding surface, which is arranged on the long tooth flanks 7 of the toothing 6.

[0072] Such a noise-reducing coating of the sliding surface 30 can be achieved with a suitable plastic cushion, a suitable plastic coating, an embedding of a sliding body or with other noise-reducing measures.

[0073] It is preferred that the sliding surface of the long tooth flank 7 is coated or covered with suitable elastomeric materials. Here too, it may be provided that the use of an additional damping element 20, 40, 50 is either provided or can be omitted entirely.

[0074] The Fig. Figures 10 to 15 show the further embodiment of contour discs in conjunction with a spur gear toothing and spur gear discs in the second freewheel system according to the independent subsidiary claim.

[0075] In Fig. Figure 10 shows that a spur gear toothing part 31 essentially consists of an external toothing body 32 which is connected to the hub body in a rotationally secure manner, wherein a spur gear toothing body 33 is integrally formed axially on the external toothing body 32, which - as in the previous embodiment - consists of long tooth flanks 37 and short tooth flanks 38.

[0076] The toothing 34 thus formed shall in turn be designed to be noise-dampened by the preferred measures.

[0077] This shows the Fig. 11, that a contour disc 40 is provided which is formed in essentially the same toothing 44 as the toothing 34 of the external toothing body 32 and which also consists of long toothing flanks 41 and short toothing flanks 42.

[0078] The difference, however, is - as in the first embodiment - that the long tooth flanks 41 form a projection 43 which, in the installed state, extends beyond the long tooth flanks 37 of the toothing 34.

[0079] This is in Fig. 12 and Fig. 13 shown.

[0080] It is shown that the contour disc 40 is fitted in the space between the outer gear body and the face gear body 33.

[0081] From the cut in Fig. 13 shows that the long tooth flanks 37 of the spur gear body 33 do not engage with the associated long tooth edges of an upper spur gear body 45, because the toothing of the contour disc 40 with its projection 43 is now located in this area.

[0082] Only in the opposite direction, when the locking position is reached, will the short tooth flanks of the upper face gear body 45 (not shown in detail) come into load-transmitting engagement with the short tooth flanks 38 of the face gear body 33. Load transmission via the flanks of the contour disc 40 is thus excluded.

[0083] Here too, it can be seen that noise reduction occurs because the long tooth flanks 37 1 The face gear body 33 is not in engagement with the long tooth flanks of the upper face gear body in the free-running position. 1 Fig. 10 45 come, but only slide along the long tooth flanks of the contour disc 40 caused by the overhang 43.

[0084] While the Fig. Figure 12 shows the radial outer arrangement of a contour disk 40. Fig. 14 the analogous representation with a contour disc 40, which is arranged on the inner circumference of the outer gear body 32. Otherwise, the same description applies to the same parts.

[0085] The Fig. Figure 15 shows that the invention does not require the contour disc 40 to necessarily have identical teeth 44 as the teeth 34 of the face gear body 33. For noise reduction, it is also sufficient that the teeth 44a of the contour disc 40 differ from the teeth 34, for example, by the teeth 44a consisting of (e.g., four) individual teeth 46, which are evenly distributed around the circumference of the contour disc 40 and form the important projection 43.

[0086] This ensures that the toothing of the upper face gear body 45 (not shown in detail) only rests on the individual teeth 46 during one rotation at a time in freewheeling mode, thus also achieving noise reduction.

[0087] However, the wear of the contour disc 40 is greater because only a few individual teeth 46 are evenly distributed around the circumference, whereas in Fig. 14 a multitude of individual teeth 46 form the uniformly circumferential toothing 44 of the contour disc.

[0088] The Fig. Figure 16 shows a further embodiment of the invention, which is to enjoy protection independently of the other embodiments. Here, the noise-reducing measure consists in the fact that the pawl 10 and its sliding surface 27 are provided with a suitable coating or have a suitable sliding element 47. In the illustrated embodiment, the sliding element 47 consists of a low-friction elastomeric plastic strip, e.g., made of a PTFE material, which is embedded in an undercut bearing groove 48 and toothed therein in order to achieve a permanent positional locking of the sliding element 47 on the sliding surface 27 of the pawl 10.

[0089] Instead of the arrangement of a sliding body 47, in another embodiment the sliding surface 27 can of course be completely coated, or a noise-damping sliding body can be glued on or arranged in a position-secured manner.

[0090] The Fig. 17 and Fig. Figure 18 shows another embodiment of a damping element, which, instead of a partially or fully toothed contour disc, is now designed as a damping ring 50. It is preferred that the damping ring 50 is designed as a round-profile O-ring. Instead of a round profile, other ring cross-sections can also be used, such as a square or rectangular cross-section. The damping ring is preferably untoothed and can be used—like a conventional sealing ring—in place of the aforementioned contour discs 20, 40. It can therefore be used both in the embodiment of a pawl freewheel and in the embodiment of a spur gear coupling. The embodiment shown according to Fig. 17 and Fig. Figure 18 shows only the application with a pawl freewheel, but the invention is not limited to this.

[0091] Accordingly, all the contour discs 20, 40 shown and described can be replaced by such a damping ring 50.

[0092] The in Fig. The damping ring 50 shown in Figure 17 is embedded in a circumferential bearing groove 49 in the space between the two toothed sections 6, 6a of the outer toothed body 5. The bearing groove 49 preferably has an undercut profile.

[0093] The damping ring 50 can also be glued in or otherwise fixed. It can also be – according to the embodiments shown in the Fig. 4a, Fig. 4b and Fig. 5, as well as Fig. 12, Fig. 13 and Fig. 14 arranged laterally on a toothing 6, 34.

[0094] The Fig.Figure 18 also shows that the damping path 51 formed by the damping ring 50 is shorter than the circumferential length of the long tooth flank 7, 7a of the external gear body 5. Thus, immediately after falling from the short tooth flank 8, 8a, the pawl 10 strikes along the shorter damping path 7, 7a of the external gear body 5 formed by the damping ring 50.

[0095] The fact that the damping distance 51 generated by the described damping elements 20, 40, 50 can be shorter than the length of the long tooth flank 7 applies to all described damping elements 20, 40, 50. Drawing legend 1 rear wheel hub 2 hub bodies 3 spoke mount 4 Separation joint 5 External gear body 6 Gearing 6a 7. Gear flank (long) 8 Gear flank (short) 9 Free space 10 locking latches 11 Arrow direction 12 internal gear bodies 13 Outer ring (of 14) 14 ball bearings 15 inner ring 16 hub axle 17 Arrow direction (free) 18 Arrow direction (lock) 19 20 contour disc 21 Gear flank (long) 22 Gear flank (short) 23 Overhang 24 teeth (out of 20) 25 positioning holes (out of 5) 26 positioning pins (out of 20) 27 sliding surfaces (out of 10) 28 Coating 29 coating bodies 30 sliding surface (out of 7) 31 Spur gear toothing part 32 External gear body 33 Front gear body (bottom) 34 gear teeth 35 36 37 Gear flank (long) 38 Gear flank (short) 39 40 contour disc 41 Gear flank (long) 42 Gear flank (short) 43 Overhang 44 Interlocking (of 40) 44a 45 Front gear body (top) 46 single teeth 47 sliding bodies (in 10) 48 Bearing groove

Claims

[1] Rear wheel hub (1) for bicycles with a freewheel based on the pawl principle, wherein an external toothed body (5) is fixed in the hub body (2) of the rear wheel hub (1) in a rotationally fixed manner, the external toothed body having radially inwardly directed teeth (6) which essentially consist of long and short tooth flanks (7, 8) uniformly arranged one after the other around the circumference, periodically repeating, which form sliding surfaces (30) for a pawl (10) sliding over them, which is arranged on an internal toothed body (12) and which, in the freewheel state, slides along at least the long tooth flanks (7) of the teeth (6, 6a) of the external toothed body (5), wherein at least one damping element (20, 50) is arranged in the free space (9) between the teeth (6, 6a) of the external toothed body (5) and the pawl (10), which has at least partially extends beyond the long tooth flanks (7) of the external tooth body (5) in a radial direction, characterized by, that the damping body is designed as a contour disc (20) which has essentially the same toothing (24) as the external toothing body (5), wherein the toothing (24) of the contour disc (20) is designed such that the pawl (10) slides along the tooth flanks (21, 22) of the noise-damping contour disc (20) in the free-running direction (17). [2] Rear wheel hub (1) according to claim 1, characterized by , that the number of teeth of the gearing (6) of the external gear body (5) is greater than or equal to the number of teeth of the gearing (24) of the contour disc (20). [3] Rear wheel hub (1) according to claim 1 or 2, characterized by , that the contour disc (20) is arranged at the edge of the toothing (6) of the external toothing body (5). [4] Rear wheel hub (1) according to claim 1 or 2, characterized by , that the contour disc (20) is arranged centrally within the toothing (6, 6a) of the external toothing body (5). [5] Rear wheel hub (1) according to claim 1, characterized by , that in addition to the use of a damping element (20, 40) to generate an additional reduction in noise during free running, the surfaces of the mutual teeth that are in sliding contact with each other are provided with noise-damping elements (29, 47) or coatings (28). [6] Rear wheel hub (1) according to claim 5, characterized by that the noise-reducing elements are designed as coating bodies (29) or as sliding bodies (47). [7] Rear wheel hub (1) according to claim 6, characterized by , that the sliding body (47) consists of a low-friction elastomeric plastic strip which is embedded in an undercut bearing groove (48) of the pawl (10) and toothed there. [8] Rear wheel hub for bicycles with freewheel according to the spur gear coupling principle, wherein a lower spur gear body (33) is fixed in a rotationally fixed position in an external gear body (32), the lower spur gear body (33) having an axially directed toothing (34) which essentially consists of long and short tooth flanks (37, 38) arranged uniformly one after the other around the circumference and repeating periodically, which form sliding surfaces for the toothing of an upper spur gear body (45) arranged at an axial distance, wherein in the freewheel state the toothing of the upper spur gear body (45) slides at least along the long tooth flanks (37) of the toothing (34) of the lower spur gear body (33), characterized by, that in the space between the toothing (34) of the lower face gear body (33) and the toothing of the upper face gear body (45) at least one damping element (40, 50) is arranged which at least partially extends beyond the long tooth flanks (37) of the lower face gear body (33) in the axial direction. [9] Rear wheel hub according to claim 8, characterized by that the damping element is designed as a contour disc (40) that is at least partially toothed or as a damping ring (50). [10] Rear wheel hub according to claim 8 or 9, characterized by , that the damping element (40, 50) is attached to the outer or inner circumference of the lower face gear body (33). [11] Rear wheel hub according to claim 8 or 9, characterized by , that the damping body (40, 50) is fixed in the space between the rows of teeth of the toothing (34) of the lower face toothing body (33).

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