Free hub with spring made of porous structured plastic

Abstract

A freewheel hub for a bicycle, the freewheel hub comprising: a hub axle; a hub sleeve rotatably supported on the hub axle; a transmission device rotatably supported on the hub axle, which can be connected with at least one pinion configuration; a freewheel device arranged between the hub sleeve and the transmission device, the freewheel device comprising: a first coupling ring which can be or has been coupled in a torque-transmitting manner with the hub sleeve, a second coupling ring which can be or has been coupled in a torque-transmitting manner with the transmission device, wherein the two coupling rings have an axial toothing which faces towards one another; a pretensioning device which is constructed and arranged to pretension the two coupling rings in an axial direction relative to one another, wherein the pretensioning device has a spring configuration which comprises at least one spring element, which is formed from a plastic having a cellular structure.

Description

Technical Field

[0001] The present invention relates to a freewheel hub for a bicycle, the freewheel hub comprising a hub axle, a hub sleeve rotatably supported on the hub axle, a transmission device rotatably supported on the hub axle and capable of being configured to be connected with at least one pinion, and a freewheel assembly disposed between the hub sleeve and the transmission device.

[0002] The freewheel assembly includes a first coupling ring that can be coupled to or is already coupled to the hub sleeve in a torque-transmitting manner, and a second coupling ring that can be coupled to or is already coupled to the transmission device in a torque-transmitting manner, wherein the two coupling rings have axial teeth facing each other. Furthermore, the freewheel assembly includes a pretensioning device constructed and arranged to pretension the two coupling rings axially relative to each other, wherein the pretensioning device has a spring configuration comprising at least one spring element. Background Technology

[0003] Freewheels are also known as axial freewheels or toothed freewheels.

[0004] For example, patent application DE 198 47 73 A1 discloses a general type of freewheel hub. This patent application describes a freewheel hub in which the preload device is formed by two steel helical compression springs.

[0005] Due to limitations in manufacturing technology, steel springs, particularly in terms of spring coil ratio, can only be used in connecting rings with a limited diameter, thus limiting the number of connecting teeth. For this reason, only a relatively large meshing angle of approximately 20° to 15° can be achieved. The force acting on the connecting teeth is also relatively large due to the limited diameter, resulting in rapid wear. Furthermore, the operating noise is typically very high when using freewheels with steel springs.

[0006] As an alternative, for example, DE 10 2015 009 143 A1 discloses a free hub with a magnetic preload device.

[0007] However, compared with free hubs with mechanical preload devices, the aforementioned free hubs have a much more complex structure, resulting in higher costs, and require high precision and tight tolerances.

[0008] Furthermore, the force applied to the coupling ring by the magnet is not evenly distributed around the hub axle, but rather acts largely in a point-like manner. In a full-suspension bicycle (MTB-Fully), at high speeds, especially when the rear wheel bounces rapidly upwards, the coupling ring begins to oscillate. Consequently, sometimes only a few teeth of the axial gear train are engaged, leading to damage to these axial gears. With increased operating time, this can potentially cause the entire freewheel to fail completely. Summary of the Invention

[0009] In view of this, the object of the present invention is to improve the general-purpose freewheel hub in terms of wear, operating noise and manufacturing difficulty.

[0010] Therefore, the present invention proposes, as an alternative to steel springs, the use of spring elements formed from porous plastics, particularly polyurethane-based plastics, preferably mixed-porous polyurethane elastomers.

[0011] For example, industrial foam materials, such as those sold by BASF, can be used. Or the name sold by Getzner is... The spring of this invention is, for example, made of SR28 type foam material. Made.

[0012] Polyurethane is resistant to grease, unaffected by temperature, and has low manufacturing costs, making it particularly suitable for use as a spring in axial freewheels.

[0013] Compared to suspension systems with steel springs, a larger coupling diameter can be achieved, resulting in a smaller engagement angle and lower forces. Wear is reduced, and operating time is correspondingly extended. Furthermore, the material's damping properties reduce noise during operation.

[0014] Compared to magnetic freewheels, the suspension system can be applied more evenly to the plane of the connecting ring.

[0015] Furthermore, the freewheel of the present invention has an extremely simple structure, does not require high precision and tight tolerances, and therefore has low manufacturing costs. The spring element, which will be described in detail below, can, for example, be made very simply from prefabricated sheet metal by means of water jet cutting.

[0016] Compared to magnetic freewheels, which require complex post-machining of the connecting ring and hub sleeve to properly position each magnet, the manufacturing difficulty of the freewheel is significantly reduced overall.

[0017] To ensure uniform force distribution, the spring configuration may include multiple spring elements of the same type, preferably distributed at the same angular distance around the hub shaft.

[0018] Preferably, each of the spring elements has an arcuate section whose convex side is adapted to press axially against one of the first and second connecting rings so that the first and second connecting rings are pre-tensioned relative to each other when the spring element is installed in the free hub.

[0019] According to a preferred embodiment, the arcuate segment is constructed as a strip segment with a substantially constant width and thickness. Such a structure can be particularly simple to produce, for example, by water jet cutting from a flat foam material board. The width of the strip segment corresponds to the thickness of the board.

[0020] Furthermore, the curved section is preferably curved around an axis that is generally parallel to the width direction of the strip section or extends generally radially after installation.

[0021] The total elasticity is influenced by material-related factors, such as the type of plastic and the shape and size of the pores, as well as geometric factors, such as the arc shape, arc radius, and strip thickness in curved sections. By appropriately combining these factors, the desired elasticity can be set in a simple way.

[0022] Only a relatively small axial reset force is required to achieve the function of a freewheel. For example, 0.2 to 0.5 N is needed for preload, and about 1 N is needed when the freewheel is in operation.

[0023] It has been shown that combining porous materials with suitable geometries of spring elements can achieve such smaller restoring forces, thereby advantageously reducing operating noise.

[0024] This is particularly relevant when the spring configuration is designed such that the elastic force required for the freewheel is generated primarily by bending stiffness rather than by the compression of the plastic. In other words, the spring configuration is preferably designed such that when a compressive force of 0.2N to 0.5N is applied axially to the spring configuration, although the spring configuration will deform, the porous structure of the plastic will not be significantly compressed.

[0025] This allows us to assume (but not to be certain) that the porous structure of the plastic reduces the bending stiffness of the spring element in a suitable manner.

[0026] When the spring configuration is formed by multiple spring elements of the same type and independently constructed, the spring elements can be used with particular flexibility, for example, for connecting rings of different diameters.

[0027] Each spring element can be constructed as a D-ring or an arc with a bent longitudinal end. Other shapes, such as rectangular or angular, can also be used, as long as the inserted spring element can be bent or return to its axial position.

[0028] To determine the mounting position of each spring element, these spring elements are preferably inserted into corresponding recesses, which are constructed within the axial surface of the hub sleeve or transmission device, i.e., a surface with an axial normal vector. Other fixing methods can also be used. For example, each spring element can be embedded in a circumferential groove of the hub sleeve or transmission device, in which suitable stops are provided to clamp the spring elements between these stops.

[0029] The installation difficulty can be greatly reduced by connecting multiple spring elements integrally, preferably in the form of a hanging strip, which forms a spring configuration.

[0030] Because the plastic material used is flexible enough, a strip with a fixed number of arcuate segments connected by planar sections can be cut from a flat plate first. Then, for example by hand, the strip can be bent around the hub shaft and embedded into a corresponding circular groove, which is provided in the axial surface of the hub sleeve or transmission device.

[0031] However, it is important to ensure that the strip is embedded in such a way that it does not deform undesirably during operation. To achieve this, appropriate structures, such as stops or protrusions, can be incorporated into the hub sleeve or transmission mechanism.

[0032] The correct installation of the preload device can be easily ensured or simplified by including a retaining ring that is adapted to fix the position of each spring element relative to each other. The retaining ring is preferably made of plastic and is suitable for hanging strips with multiple spring elements or for individual spring elements.

[0033] According to a preferred embodiment, the retaining ring includes an annular base and a plurality of retaining elements distributed around the periphery of the base and radially protruding from the base, the retaining elements partially axially covering the spring configuration on one side and preferably radially encircling the spring configuration from the inside and outside.

[0034] This structure is particularly suitable for the aforementioned strip with alternating arcuate and planar sections, in which the strip can be embedded into the retaining ring such that the retaining element covers or encircles the planar section.

[0035] Furthermore, the preload device includes a cover ring, which can be mounted on the retaining ring such that the spring configuration is at least partially accommodated between the retaining ring and the cover ring, particularly in the area of ​​the planar section, and together with the retaining ring and the cover ring, forms a securely engaged assembly. This prevents the spring configuration from detaching from the retaining ring and allows the preload device, as a spare part, to be handled in a particularly simple manner.

[0036] Finally, protection is also requested for the preload device for a freewheel hub as described above.

[0037] The pretensioning device may, for example, be formed by a plurality of independent individual spring elements, or by a hanging spring configuration, particularly in the form of a strip of planar sections (acting as spacers) having alternating arcuate sections (acting as spring elements), or by a spring configuration with a retaining ring, or by a spring configuration with a retaining ring and a cover ring, wherein each individual spring element or the spring configuration is formed of a plastic material having a porous structure. Attached Figure Description

[0038] The present invention will now be described with reference to several selected embodiments shown in the accompanying drawings.

[0039] in:

[0040] Figure 1 This is a longitudinal sectional view of a first embodiment of the freewheel hub of the present invention.

[0041] Figure 2 for Figure 1 A magnified view of the area denoted by II in the image.

[0042] Figure 3 for Figure 1 An exploded view of the preload device on the free hub.

[0043] Figure 4 for Figure 3 A perspective view of the pre-tightening device in its assembled state.

[0044] Figure 5 for Figure 3 The spring configuration of the preload device is shown in the side view before it is embedded in the retaining ring.

[0045] Figure 6 for Figure 5 A bottom view of the target object.

[0046] Figure 7 for Figure 5 A magnified view of the area denoted by VII in the middle.

[0047] Figure 8 An exploded view of key components of a second embodiment of the freewheel hub of the present invention, and

[0048] Figure 9 This is an exploded view of an important component of the third embodiment of the freewheel hub of the present invention. Detailed Implementation

[0049] For clarity, not all features in every figure are labeled; rather, only those features necessary to illustrate the corresponding figure are labeled. This is particularly true when a figure contains multiple similar features.

[0050] The same or corresponding features in different embodiments are provided with the same reference numerals. The second and third embodiments are described only in terms of their differences from the first embodiment, while other aspects refer to the description of the first embodiment.

[0051] Figure 1 The diagram shows a longitudinal sectional view of a first embodiment of the freewheel hub 10 of the present invention, wherein the longitudinal axis M of the freewheel hub is contained within the cutting plane. Throughout this application, unless otherwise stated, the term "axial" always refers to this longitudinal axis M, which coincides with the rear axle of the bicycle after installation.

[0052] The freewheel hub 10 includes a hub axle 12, which can be fixed to the bicycle frame in a known manner. A hub sleeve 14 is rotatably supported on the hub axle 12 by two rolling bearings 11 and 13, and a drive unit 16 is supported by two more rolling bearings 15 and 17. The hub sleeve 14 and the drive unit 16 are axially secured to the hub axle 12 by sealing elements 19 and 21.

[0053] At the longitudinal end of the hub sleeve 14 facing the drive unit 16, the hub sleeve has a circumferential axial groove 22 that accommodates the freewheel assembly 18, which will be described in detail below. Furthermore, the hub sleeve 14 has two spoke flanges 23 and 25 on which spokes can be mounted in a known manner.

[0054] The transmission device 16 can be connected to a pinion configuration (not shown) through which torque is introduced into the transmission device 16 and transmitted to the hub sleeve 14 and thus to the rear wheel of the bicycle.

[0055] The freewheel assembly 18 is arranged between the hub sleeve 14 and the transmission device 16 and in the groove 22, and is sealed to the outside by another sealing element 31.

[0056] It is possible Figure 2 The enlarged view shows the freewheel assembly 18 more clearly. The freewheel assembly includes a first connecting ring 24, a second connecting ring 26, and a pre-tensioning device 28.

[0057] The first connecting ring 24 is coupled to the hub sleeve 14 in a torque-transmitting manner, and the second connecting ring 26 is coupled to the transmission device 16 in a torque-transmitting manner. Therefore, the radial external teeth 24a or 16a and the internal teeth 14i or 26i provided on the corresponding components can optimally utilize the second embodiment. Figure 8 As can be seen in the perspective diagram, but the same applies to all embodiments.

[0058] To achieve the freewheel, the first connecting ring 24 and the second connecting ring 26 also have axial teeth 24z, 26z facing each other and including inclined sliding surfaces in a known manner (see...). Figure 8 and Figure 9 ), and are pre-tensioned relative to each other in the axial direction by the pre-tensioning device 28.

[0059] Apart from the specific design of the preload device 28, which will be detailed below, the structure and operation of the freewheel shown are known. For example, see the two disclosures mentioned at the beginning of this article.

[0060] exist Figures 1 to 7 In the first embodiment, the pre-tightening device 28 is composed of... Figure 3 China-Israel decomposition diagram and in Figure 4 The spring configuration 30, retaining ring 40 and cover ring 46 shown in the assembled state are formed, and in the assembled state, the aforementioned three components form a firmly connected assembly 48.

[0061] The spring configuration 30 includes a plurality of spring elements 32, which, according to the invention, are made of a porous plastic material, such as a polyurethane-based foam.

[0062] exist Figures 1 to 8 In the first and second embodiments, the five identical spring elements 32 are integrally connected in the form of a hanging strip 34. The strip 34 includes identical arcuate segments 32b forming actual spring elements 32 and identical planar segments 36 alternately arranged between the arcuate segments 32b to form spacers. The strip 34 also has planar end segments 37 at both longitudinal ends, the length of which is about half or less of the length of the remaining planar segments 36.

[0063] The precise shape of strip 34 can be cut from a sufficiently flexible, porous plate-like starting material. Figures 5 to 7 The images are shown in different views. In the example shown, the shape of the strip is mirror-symmetric with respect to the plane of symmetry S. Figures 5 to 7 The strip is shown in its initial state before bending around an axis parallel to the thickness direction D of the strip.

[0064] The width b of strip 34 (see) Figure 6 The width b is preferably kept constant within the length range of the strip, and can be, for example, 3 mm to 5 mm. The width b can be given, for example, by the thickness of the plate-like starting material.

[0065] The thickness d of the strip is preferably constant, and preferably 1.5 mm to 2.5 mm, while its total length l can be approximately 135 mm to 139 mm. The inner radius r of the arc segment 32b is, for example, 12 mm to 14 mm, and the length lb of the arc segment is, for example, 18 mm to 20 mm. The distance a1 between the center points of adjacent arc segments 32b can be 26 mm to 29 mm, and the distance a2 between the longitudinal end of an adjacent arc segment and its center point is approximately 13 mm to 15 mm.

[0066] Of course, the dimensions of the strip, such as total length, width, thickness and radius of curvature, need to be matched with the specific requirements of the case, that is, with the dimensions of the freewheel hub, especially the connecting ring, the characteristics of the porous plastic material used, the desired elasticity, etc.

[0067] In the first embodiment, the strip 34 forming the spring configuration 30 is bent by hand around an axis parallel to the thickness direction D of the strip 34 and inserted into the retaining ring 40.

[0068] It can be best from Figure 3 As can be seen from the exploded view, the retaining ring 40 includes an annular base 42 and five retaining elements 44 that protrude radially outward from the base.

[0069] The retaining element 44 is generally U-shaped and has an outer foot 43, a top surface 45, and an inner foot 47, which is adjacent to and integrally connected to the base 42. The planar section 36 of the strip 34 is inserted or clamped into the resulting socket 44u, thereby fixing the position of the spring elements 32 relative to each other.

[0070] One of the retaining elements 44 also has an inner partition wall 49 against which the end face 34s of the strip 34 can be abutted, thereby simplifying installation. As a supplementary option, it should be noted that... Figure 1 and Figure 2 The cutting plane in the middle just passes through this inner partition wall 49, which can be Figure 2 The lower part is clearly visible.

[0071] After the strip 34 is embedded into the retaining ring 40, the cover ring 46 can be mounted on the retaining ring 40. For this purpose, in this embodiment, the cover ring 46 is provided with corresponding protrusions 46p1 and 46p2, and the retaining element 44 is provided with grooves 44r1 and 44r2 that match these protrusions. For example, a tight fit, a conical fit (as at 46p1 and 44r1), or a snap-fit ​​connection can be used. In this embodiment, the cover ring 46 is constructed as a flat annular disc, which, in addition to the structure for fastening to the retaining ring, also has several rib structures 46r for improving rigidity.

[0072] like Figure 4As shown, with the preload device 28 assembled, the planar section 36 of the spring configuration 30 is fixedly housed between the retaining ring 40 and the cover ring 46, and the preload device 28, as a spare part, can be easily transported. The risk of the strip 34 undesirably bending when mounted on the hub sleeve 14 is minimized.

[0073] The retaining ring 40 and the cap ring 46 can be made of suitable plastic materials, for example, by injection molding.

[0074] After the freewheel hub 10 is assembled, each convex side 32bk in the arc-shaped section 32b is pressed axially against the first connecting ring 24 to pre-tension this first connecting ring to the second connecting ring 26. Because the number of contact points between the spring configuration 30 and the first connecting ring 24 is relatively large and these contact points are evenly distributed around the hub axle 12, the suspension system can be evenly applied to the connecting rings 24 and 26. The spring strip is preferably designed such that only bending stiffness, rather than the compression of the plastic, generates the elastic force required for the freewheel, and the porous structure is not significantly compressed during operation. This allows the bending stiffness of the spring configuration to be reduced appropriately through the porous structure.

[0075] Alternatively, the cover ring 46 can be omitted, in which case a simplified solution of the retaining ring (not shown) can be applied, since no structure for fastening to the cover ring is needed in this case.

[0076] like Figure 8 As shown in the second embodiment, although the installation requirements are more stringent, the strip 34 can also be inserted into the groove 22 of the hub sleeve 14 simply as a pretensioning device 28 (i.e., excluding the retaining ring and the cover ring).

[0077] For clarity, Figure 8 and Figure 9 In particular, the closure element 31 is not shown in the views of the second and third embodiments (see [reference]). Figure 1 ).

[0078] As an alternative to the integrally formed strip, such as Figure 9 As shown in the third embodiment, multiple independent spring elements 32, for example in the form of independent D-rings 33, can also be used. These D-rings 33 can also be cut from suitable foam material boards with relatively little difficulty. Alternatively, multiple independent spring elements, whose appearance generally corresponds to... Figure 7 That is, it includes a central arc-shaped section and a bent, flat longitudinal end.

[0079] To prevent the spring elements 32 from undesirably sliding relative to each other during the operation of the free hub 10, corresponding recesses can be provided in the axial plane of the hub sleeve 14, in which the spring elements 32 can be inserted or clamped. However, this increases the difficulty of machining the hub sleeve 14. Alternatively, retaining rings with suitable construction can be used for the individual spring elements, which fix the spring elements in their relative positions relative to each other.

Claims

1. A freewheel hub for a bicycle, the freewheel hub comprising: hub axle Hub sleeve rotatably supported on the hub axle A transmission device rotatably supported on the hub axle and capable of being connected to at least one pinion. A freewheel assembly disposed between the hub sleeve and the transmission device, the freewheel assembly comprising: A first connecting ring that can be coupled to the hub sleeve in a torque-transmitting manner, or that is already coupled to the hub sleeve in a torque-transmitting manner. A second coupling ring that can be coupled to the transmission device in a torque-transmitting manner, or that has already been coupled to the transmission device in a torque-transmitting manner, wherein the first coupling ring and the second coupling ring have axial teeth facing each other. A pretensioning device, constructed and arranged to pretension the first connecting ring and the second connecting ring axially relative to each other, wherein the pretensioning device has a spring configuration including at least one spring element, and The spring element is formed of a plastic with a porous structure. The spring element, or each of the spring elements, is characterized in that it has an arc-shaped segment, the convex side of which is adapted to press axially against one of the first and second connecting rings to pre-tension the first and second connecting rings relative to each other. The spring configuration is formed by multiple spring elements of the same type and independently constructed.

2. The freewheel hub for a bicycle according to claim 1, characterized in that, The spring element comprises or is formed of polyurethane-based plastic.

3. The freewheel hub for a bicycle according to any one of the preceding claims, characterized in that, The spring configuration includes a plurality of spring elements distributed around the periphery of the hub axle.

4. The freewheel hub for a bicycle according to claim 1 or 2, characterized in that, The spring configuration includes multiple spring elements of the same type, which are distributed around the periphery of the wheel hub axle.

5. The freewheel hub for a bicycle according to claim 1 or 2, characterized in that, The arc-shaped segment is constructed as a strip segment with a generally constant width and thickness.

6. The freewheel hub for a bicycle according to claim 1 or 2, characterized in that, The spring configuration is designed such that when a clamping force of 0.2 N to 0.5 N is applied axially to the spring configuration, although the spring configuration will deform, the porous structure of the plastic will not be compressed.

7. The freewheel hub for a bicycle according to claim 1 or 2, characterized in that, Each spring element is constructed as a D-ring or an arc with a bent longitudinal end.

8. The freewheel hub for a bicycle according to claim 1 or 2, characterized in that, The spring element is inserted into a corresponding recess, which is constructed within the axial surface of the hub sleeve or the axial surface of the transmission device.

9. A freewheel hub for a bicycle, the freewheel hub comprising: hub axle Hub sleeve rotatably supported on the hub axle A transmission device rotatably supported on the hub axle and capable of being connected to at least one pinion. A freewheel assembly disposed between the hub sleeve and the transmission device, the freewheel assembly comprising: A first connecting ring that can be coupled to the hub sleeve in a torque-transmitting manner, or that is already coupled to the hub sleeve in a torque-transmitting manner. A second coupling ring that can be coupled to the transmission device in a torque-transmitting manner, or that has already been coupled to the transmission device in a torque-transmitting manner, wherein the first coupling ring and the second coupling ring have axial teeth facing each other. A pretensioning device, constructed and arranged to pretension the first connecting ring and the second connecting ring axially relative to each other, wherein the pretensioning device has a spring configuration including at least one spring element, and The spring element is formed of a plastic with a porous structure. The spring element, or each of the spring elements, is characterized in that it has an arc-shaped segment, the convex side of which is adapted to press axially against one of the first and second connecting rings to pre-tension the first and second connecting rings relative to each other. Multiple spring elements of the same type are integrally connected to form the spring configuration.

10. The freewheel hub for a bicycle according to claim 9, characterized in that, The spring elements are connected in the form of hanging strips.

11. The freewheel hub for a bicycle according to claim 9 or 10, characterized in that, The spring elements are distributed circumferentially around the hub shaft, and the preload device also has a retaining ring adapted to fix the position of each spring element relative to each other.

12. The freewheel hub for a bicycle according to claim 11, characterized in that, The retaining ring includes an annular base and a plurality of retaining elements distributed around the periphery of the base and radially protruding from the base, the retaining elements partially axially covering the spring configuration on one side.

13. The freewheel hub for a bicycle according to claim 11, characterized in that, The retaining ring includes an annular base and a plurality of retaining elements distributed around the periphery of the base and radially protruding from the base, the retaining elements partially axially covering the spring configuration on one side and radially encircling the spring configuration from the inside and outside.

14. The freewheel hub for a bicycle according to claim 11, characterized in that, The preload device also includes a cover ring, which can be mounted on the retaining ring such that the spring is at least partially accommodated between the retaining ring and the cover ring, and together with the retaining ring and the cover ring, forms a securely engaged assembly.

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