Bicycle sprocket and manufacturing method thereof

Abstract

A bicycle sprocket comprises a first disc body, a second disc body and a support layer. The first disc body is made of a first non-metal material and has a plurality of teeth on the outer periphery of the first disc body. The second disk body is made of a second non-metal material. The second disk body covers one side of the first disk body and surrounds an inner space with the first disk body. The inner space is annular. The support layer is made of a third non-metal material and is arranged in the inner space. A method for manufacturing a bicycle transmission gear disc is also provided.

Description

[Technical Field]

[0001] This invention relates to a geared disc and a method for manufacturing the same, particularly to a transmission geared disc for bicycles and a method for manufacturing the same. [Previous Technology]

[0002] In cycling, the weight of the bicycle causes an excessive energy burden for the rider. Therefore, reducing the weight of the bicycle has become one of the main directions of bicycle development.

[0003] In reducing the weight of a bicycle, in addition to improving the design of the frame structure, the weight can also be reduced by changing the type of frame material. Due to the different properties of materials, the original frame structure design may not provide sufficient frame strength after changing the type of frame material. Therefore, the frame structure design should also be adjusted accordingly to the change of frame material. [Summary of the Invention]

[0004] The present invention provides a transmission gear for bicycles, which has the advantages of being lightweight and having high structural strength.

[0005] To achieve the above advantages, one embodiment of the present invention provides a bicycle drive sprocket, comprising: a first sprocket body, a second sprocket body, and a support layer. The first sprocket body is made of a first non-metallic material. The first sprocket body has a plurality of teeth on its outer periphery. The second sprocket body is made of a second non-metallic material. The second sprocket body covers one side of the first sprocket body and together with the first sprocket body surrounds an internal space, the internal space being annular. The support layer is made of a third non-metallic material and disposed within the internal space, and the third non-metallic material is different from the first and second non-metallic materials.

[0006] In one embodiment, the first or second disc body is provided with a plurality of ribs on the side facing the interior space. These ribs extend radially along the transmission gear disc, and the interior space is divided into a plurality of compartments by the ribs.

[0007] In one embodiment, the first disk body described above includes a first disk surface and a first annular wall protruding from the first disk surface.

[0008] In one embodiment, the second disk body includes a second disk surface and a second annular wall protruding from the second disk surface, and the first annular wall and the second annular wall are attached to each other.

[0009] In one embodiment, the first disk body is provided with a central axis, the first disk surface, the second disk surface of the second disk body and the first annular wall or the second annular wall together constitute an internal space, and the distance between the first disk surface and the second disk surface gradually decreases from the first annular wall in a radial direction away from the central axis.

[0010] In one embodiment, the first non-metallic material and the second non-metallic material are fiber composite materials, and the third non-metallic material is a foamed material.

[0011] In another embodiment, the first non-metallic material and the second non-metallic material are made of the same material.

[0012] In one embodiment, the first disc body and the second disc body are integrally formed.

[0013] The present invention also provides a method for manufacturing a bicycle drive sprocket, comprising the following steps: A support layer made of a third non-metallic material is disposed on at least one of a first sprocket body made of a first non-metallic material and a second sprocket body made of a second non-metallic material. The first sprocket body and the second sprocket body are connected to form an internal space, and the support layer is located within the internal space. The first sprocket body, the second sprocket body, and the support layer are heated to cause the first sprocket body and the second sprocket body to join together, and the support layer to expand to support the internal space.

[0014] In one embodiment, one of the first disc body or the second disc body is provided with a plurality of ribs on the side near the other of the first disc body or the second disc body. The ribs extend radially along the transmission gear disc, and the internal space is divided into a plurality of compartments by the ribs.

[0015] In one embodiment, in the step of providing a support layer on at least one of the first disk and the second disk, the support layer is provided on each of the first disk and the second disk, and then the disk expands due to heat to support the internal space.

[0016] Based on the above description, in the bicycle drive chainring and its manufacturing method of the present invention, the first chainring and the second chainring are made of non-metallic materials, thus having the advantage of being lightweight. Furthermore, because a support layer made of non-metallic material is provided in the internal space surrounded by the first chainring and the second chainring, the first chainring and the second chainring can be supported through the support layer, thereby strengthening the structural strength of the bicycle drive chainring while maintaining its lightweight advantage.

[0017] In order to make the above and other objects, features and advantages of the present invention more apparent and understandable, embodiments are described below in detail with reference to the accompanying drawings.

Implementation Method

[0018] In the following text, the terms used in the description of embodiments according to the present invention, such as "upper" and "lower" indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings. The above terms are only for the convenience of describing the present invention and are not intended to limit the present invention, that is, they do not indicate or imply that the mentioned elements must have a specific orientation or be constructed in a specific orientation. In addition, the terms "first" and "second" mentioned in this specification or the claims are only used to name the elements or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

[0019] Figure 1 is an exploded view of a bicycle drive gear in one embodiment of the present invention. Figure 2 is an assembled view of the bicycle drive gear in Figure 1. Figure 3 is a cross-sectional view along line AA in Figure 1. Figure 4 is a cross-sectional view of Figure 3 after the support layer has been removed. Figure 5 is a back view of the second disc in Figure 1.

[0020] As shown in Figures 1 to 3, a bicycle transmission sprocket 100 in one embodiment of the present invention includes: a first sprocket body 1, a second sprocket body 2, and a support layer 3. The first sprocket body 1 is made of a non-metallic material, such as carbon fiber composite, glass fiber composite, plastic steel, or other high-strength polymer materials. The first sprocket body 1 has multiple teeth 1a on its outer periphery. The second sprocket body 2 is made of a non-metallic material, such as carbon fiber composite, glass fiber composite, plastic steel, or other high-strength polymer materials. The first sprocket body 1 and the second sprocket body 2 can be made of the same material, depending on the required strength and weight of the finished product. The second sprocket body 2 covers one side of the first sprocket body 1 and together with the first sprocket body 1, forms an internal space S. The internal space S is annular, and the center of the second sprocket body 2 and the internal space S is located on the central axis A of the first sprocket body 1. As shown in Figure 3, the support layer 3 is made of a third non-metallic material and is disposed within the internal space S. The third non-metallic material differs from the first and second non-metallic materials, but will be described in detail later.

[0021] In this embodiment, the central shaft of the bicycle transmission gear 100 and the central shaft of the second disc body 2 also coincide with the central shaft A.

[0022] In this embodiment, the bicycle drive sprocket 100 further includes, for example, a claw 4 for connecting to, for example, a bicycle crank (not shown) and a sprocket 5 (see FIG. 2). The claw 4 is, for example, cross-shaped, but is not particularly limited. The center of the claw 4 is located on the bottom bracket A and has a connection hole 41 suitable for connecting to the bicycle crank. The material of the claw 4 is not particularly limited and can be selected as needed.

[0023] As shown in Figures 1 to 3, the first disc body 1 in this embodiment can be integrally molded using carbon fiber composite material. When the bicycle drive sprocket 100 is combined with the bicycle frame (not shown), the first disc body 1 is located, for example, on the side of the bicycle drive sprocket 100 away from the bicycle frame. The first disc body 1 is, for example, annular and includes a first disc wall 11, a first annular wall 12, and a plurality of fixing parts 13.

[0024] Continuing from the above, in this embodiment, the first disc wall 11 has a first disc surface 110 on the side facing the second disc body 2 (i.e., the side of the first disc wall 11 facing the bicycle frame when assembled). The normal direction of the first disc surface 110 is, for example, parallel to the central axis A. In this embodiment, the first disc wall 11 has a plurality of grooves 111, and the first disc surface 110 is, for example, the bottom surface of the grooves 111, but is not limited thereto. The teeth 1a of the first disc body 1 are, for example, located at the outer periphery of the first disc wall 11.

[0025] In this embodiment, the first annular wall 12 is located at the inner periphery of the first disc wall 11. The first annular wall 12 protrudes toward the second disc body 2, for example, from the surface of the first disc surface 110 along an extension direction parallel to the central axis A of the bicycle drive chainring 100. The outer wall surface of the first annular wall 12 (the wall surface of the first annular wall 12 facing away from the central axis A) is, for example, perpendicular to the first disc surface 110, but is not limited thereto.

[0026] Subsequently, the fixing part 13 is, for example, a plurality of blocks protruding from the inner wall surface of the first annular wall 12 (the wall surface of the first annular wall 12 facing the central shaft A) toward the central shaft A of the bicycle drive chain 100. The number of fixing parts 13 corresponds, for example, to the number of the endpoints of the claw part 4, and the shape of the fixing part 13 corresponds, for example, to the shape of the endpoints of the claw part 4.

[0027] When the first disc body 1 and the claw part 4 are combined, each end point of the claw part 4 is connected to the fixing part 13 of the first disc body 1. The connection method between the fixing part 13 and the claw part 4 is not limited, such as screwing or gluing, and can be set according to requirements. The shape of the first disc body 1 can be set according to requirements. In the embodiment not shown in the figure, the first disc body 1 and the claw part 4 can be integrally formed.

[0028] As shown in Figures 1 to 3 and Figure 5, specifically, the second disk 2 can be integrally molded using carbon fiber composite material. In this embodiment, the outer diameter and inner diameter of the second disk 2 are, for example, smaller than the outer diameter and inner diameter of the first disk 1, respectively. The second disk 2 is, for example, annular. The second disk 2 includes an annular second disk wall 21 and a second annular wall 22.

[0029] As shown in Figures 1 to 5, in this embodiment, the second disk wall 21 has a second disk surface 210 on the side facing the first disk body 1. The second disk wall 21 extends obliquely from the side close to the central axis A towards the direction away from the central axis A by, for example, a second annular wall 22, and gradually approaches the first disk body 1. The size of the second disk wall 21 is such that, when the first disk body 1 and the second disk body 2 are combined, it can completely cover the size of each groove 111 on the first disk body 1.

[0030] The shape of the second disk wall 21 is not particularly limited. In this embodiment, the second disk wall 21 has a stepped structure on the surface opposite the second disk surface 210, and has a plurality of first ring portions 212 and a plurality of second ring portions 213. For example, there are three first ring portions 212, one of which is located at the outer edge of the second disk body 2. Each first ring portion 212 extends obliquely from the side near the central axis A toward a direction away from the central axis A and gradually approaches the side of the second disk body 2 closest to the first disk body 1. For example, there are two second ring portions 213. Each second ring portion 213 connects to two adjacent first ring portions 212 and is not parallel to the first ring portions 212.

[0031] The second annular wall 22 extends, for example, from the inner edge of the second disc surface 210 along the extension direction parallel to the central axis A of the bicycle drive sprocket 100 toward the side where the first disc body 1 is located, and is adapted to contact the first annular wall 12 when the second disc body 2 is combined with the first disc body 1.

[0032] As shown in Figures 3 and 4, during assembly, the first annular wall 12 and the second annular wall 22 are in contact with each other, and the portion of the first disk wall 11 near its outer periphery is also in contact with the outer periphery of the second disk wall 21. In this embodiment, the inner wall surface of the second annular wall 22 (the wall surface of the second annular wall 22 facing towards the central axis A) is attached to the outer wall surface of the first annular wall 12. Therefore, the internal space S is jointly formed by the first disk surface 110, the second disk surface 210, and the second annular wall 22, but this can be configured according to requirements. As can be seen from Figures 3 or 4, the distance between the first disk surface 110 and the second disk surface 210 gradually decreases radially away from the central axis A from the first annular wall 12.

[0033] As can be seen from Figures 3 and 4, since the first disc surface 110 is located on the bottom surface of the groove 111, the volume of the internal space S can be increased and the volume and weight of the first disc body 1 can be reduced by setting the groove 111.

[0034] The detailed connection method between the first disc 1 and the second disc 2 can be set according to the requirements. For example, the parts of the first disc 1 and the second disc 2 that are in contact can be melted by heating and joined together, or an adhesive can be provided between the first disc 1 and the second disc 2.

[0035] Since there is no particular limitation on the size relationship between the second disk 2 and the first disk 1, the internal space S can be formed by the first disk surface 110, the second disk surface 210 and the first annular wall 12 in an embodiment not shown in the figure, based on the relative size relationship between the first annular wall 12 and the second annular wall 22.

[0036] As shown in Figures 1 to 5, in this embodiment, the first disc body 1 and the second disc body 2 each form ribs 112 and 211 on the side facing the internal space S. These ribs (ribs 112 and 211) extend radially along the bicycle drive chainring 100, and the internal space S is divided into multiple compartments through these ribs (ribs 112 and 211). The compartments are, for example, not connected to each other, but are not limited thereto.

[0037] As shown in Figure 1, the rib 112 of the first disc 1 is formed, for example, between two grooves 111 of the first disc wall 11, and serves as a wall surface separating two adjacent grooves 111. As shown in Figure 5, the rib 211 of the second disc 2 is formed, for example, between the second disc surface 210 and the second annular wall surface, and is, for example, opposite to the rib 112 of the first disc 1. The ribs 112 and 211 can engage with each other when the first disc 1 and the second disc 2 are combined, and divide the internal space S into multiple non-communicating chambers. However, it should be understood that the detailed shape of the ribs 112 and 211 can be set according to requirements.

[0038] There is no particular limitation on the arrangement of ribs 112 and 211. In this embodiment, the bicycle drive chain 100 includes, for example, a plurality of chain screws 6. Ribs 112 and 211 extend radially from the bottom axle A toward the location of the chain screws 6, and a notch 211a is formed on the outer periphery of the second disc body 2 for the chain screws 6 to pass through, but this is not a limitation.

[0039] As shown in Figures 3 and 4, the support layer 3 is disposed in the internal space S. The shape of the support layer 3 corresponds to the shape of the internal space S, and it can contact the sidewalls of the first disk surface 110, the second disk surface 210, the second annular wall 22, the ribs 112 and 211. By contacting the first disk surface 110 and the second disk surface 210, the support layer 3 can support the first disk body 1 and the second disk body 2. The support layer 3 may contain, for example, a foam material that expands when heated and a colloid that dissolves when heated, and the type of material is not limited. The foam material may be expanded microspheres, but can be selected according to requirements. The volume of the support layer 3 is not particularly limited, for example, it can fill the entire volume of the internal space S. Through the above structure, when assembled, the first disk body 1 and the second disk body 2 can be bonded to each other through the support layer 3.

[0040] Figure 6 is a schematic flowchart of a manufacturing method according to an embodiment of the present invention. As shown in Figure 6, an embodiment of the present invention provides a method for manufacturing a bicycle drive sprocket, comprising the following steps: Step S1: A support layer made of a third non-metallic material is disposed on at least one of a first sprocket body made of a first non-metallic material and a second sprocket body made of a second non-metallic material. Step S2: The first sprocket body and the second sprocket body are connected to form an internal space, and the support layer is located within the internal space. Step S3: The first sprocket body, the second sprocket body, and the support layer are heated to make the first sprocket body and the second sprocket body join together, and the support layer expands to support the internal space.

[0041] The above-mentioned method for manufacturing a bicycle drive sprocket can be used to manufacture the aforementioned bicycle drive sprocket 100.

[0042] Please refer to Figures 1 to 6. In this embodiment, in step S1 above, a support layer 3 is provided in the groove 111 of the first disc 1 and the second disc surface 210 of the second disc 2, and then the support layer expands under heat to support the internal space S. However, in other embodiments, the support layer 3 before expansion may be provided only in one of the first disc 1 or the second disc 2.

[0043] In this embodiment, in step S2 above, the first disc 1 and the second disc 2 are respectively set on the male mold and the female mold of the mold (not shown in the figure), and the first disc 1 and the second disc 2 are brought into contact with each other by connecting the male mold and the female mold. However, the detailed setting method can be changed according to the requirements.

[0044] In this embodiment, in the above step S3, the first plate 1, the second plate 2 and the unexpanded support layer 3 are heated by heating the mold.

[0045] The form of the support layer 3 before expansion is not particularly limited, and it can be solid, liquid, sheet or coating. There is no limitation on the timing of setting the tooth 1a, and it can be before step S1, after step S3 or between any two steps from step S1 to step S3.

[0046] In this embodiment, no additional adhesive is provided on the first disc 1 and the second disc 2 except for the support layer 3. Specifically, in this embodiment, during step S3, the first disc 1 and the second disc 2 can be heated by a heatable mold while they are clamped together, causing a portion of them to melt and thus joining the contacting parts of the first disc 1 and the second disc 2 together. However, this is not a limitation.

[0047] Through the above method, since the support layer 3 can be uniformly disposed on the first disc 1 and the second disc 2 before they are joined, the distribution of the support layer 3 is more uniform after expansion. Compared with the method of additionally injecting support layer 3 material into the internal space S, in this embodiment, the support layer 3 is less likely to apply uneven stress to different parts of the first disc 1 and the second disc 2, thus avoiding deformation of the first disc 1 and the second disc 2. In addition, since the first disc 1 and the second disc 2 are placed in the mold and supported by the mold during the heating and expansion process, the first disc 1 and the second disc 2 are less likely to deform when the support layer 3 expands. Furthermore, since this method does not require additional holes on the first disc 1 and the second disc 2 for the support layer 3 to enter the internal space S from the outside, the structure of the first disc 1 and the second disc 2 is intact and has high strength, and no additional sealing step is required.

[0048] Based on the above description, in the bicycle drive chainring and its manufacturing method of the present invention, the first chainring and the second chainring are made of non-metallic materials, thus having the advantage of being lightweight. Moreover, because a support layer made of non-metallic material is provided in the internal space surrounded by the first chainring and the second chainring, the first chainring and the second chainring can be supported through the support layer, thus strengthening the structural strength of the bicycle drive chainring while maintaining the advantage of being lightweight.

[0049] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Those skilled in the art to which the present invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0050] Figure 1 is an exploded view of a bicycle drive gear in an embodiment of the present invention; Figure 2 is an assembled view of the bicycle drive gear in Figure 1; Figure 3 is a cross-sectional view of line AA in Figure 1; Figure 4 is a cross-sectional view of Figure 3 after the support layer is removed; Figure 5 is a back view of the second disc in Figure 1; Figure 6 is a flowchart of a method for manufacturing a bicycle drive gear in an embodiment of the present invention.

Claims

1. A bicycle drive sprocket, comprising: A first disc body made of a first non-metallic material, the first disc body having a plurality of teeth on its outer periphery; A second disc body made of a second non-metallic material covers one side of the first disc body and together with the first disc body surrounds an internal space, the internal space being annular; a support layer made of a third non-metallic material is disposed within the internal space, and the third non-metallic material is different from the first non-metallic material and the second non-metallic material.

2. The bicycle drive chainring as claimed in claim 1, wherein the first chainring or the second chainring has a plurality of ribs formed on the side facing the interior space, the ribs extending radially along the support layer, and the interior space being divided into a plurality of compartments by the ribs.

3. The bicycle drive sprocket as claimed in claim 2, wherein the first sprocket body includes a first sprocket surface and a first annular wall protruding from the first sprocket surface.

4. The bicycle drive sprocket as claimed in claim 3, wherein the second sprocket body includes a second sprocket surface and a second annular wall protruding from the second sprocket surface, and the first annular wall and the second annular wall are in contact with each other.

5. The bicycle drive chainring as claimed in claim 4, wherein the first chainring body has a central shaft, the first chainring surface, the second chainring surface of the second chainring body, and at least one of the first annular walls or the second annular walls together constitute the internal space, and the distance between the first chainring surface and the second chainring surface gradually decreases from the first annular wall along the radial direction away from the central shaft.

6. The bicycle drive sprocket as claimed in claim 1, wherein the first non-metallic material and the second non-metallic material are fiber composite materials, and the third non-metallic material is a foamed material.

7. The bicycle drive sprocket as claimed in claim 6, wherein the first non-metallic material and the second non-metallic material are made of the same material.

8. The bicycle drive sprocket as claimed in claim 1, wherein the first sprocket body and the second sprocket body are integrally formed.

9. A method for manufacturing a bicycle drive sprocket, comprising: A support layer made of a third non-metallic material is disposed on at least one of a first disc made of a first non-metallic material and a second disc made of a second non-metallic material, wherein the third non-metallic material is different from the first non-metallic material and the second non-metallic material; the first disc and the second disc are connected to form an internal space, and the support layer is located within the internal space; the first disc, the second disc and the support layer are heated to make the first disc and the second disc join together, and the support layer expands to support the internal space.

10. A method of manufacturing a bicycle drive sprocket as claimed in claim 9, wherein one of the first sprocket body or the second sprocket body has a plurality of ribs formed on a side near the other of the first sprocket body or the second sprocket body, the ribs extending radially along the drive sprocket body, and the internal space being divided into a plurality of compartments by the ribs.

11. In the method of manufacturing a bicycle drive chainring as described in claim 9, in the step of providing the support layer on at least one of the first chainring and the second chainring, the support layer is provided on each of the first chainring and the second chainring, and then they are heated and expanded to jointly support the internal space.

12. The method for manufacturing a bicycle drive chainring as claimed in claim 9, wherein the first non-metallic material and the second non-metallic material are fiber composite materials, and the third non-metallic material is a foamed material.

13. The method for manufacturing a bicycle drive sprocket as claimed in claim 12, wherein the first non-metallic material and the second non-metallic material are of the same material.

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