Bevel gear device of the transmission shaft

Abstract

A bevel gear device for a transmission shaft is applicable to connect the transmission shaft of a bicycle to a wheel hub, and the wheel hub is sleeved on a shaft rod. The bevel gear device includes a bevel gear unit and a dry bearing unit. The bevel gear unit has a bevel gear for engaging with the transmission shaft and a one-way transmission coupling group for driving the wheel hub to rotate in one direction. The ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear is 0.164 - 0.24. By respectively arranging the bevel gear and the one-way transmission coupling group at both ends of the bevel gear unit, the transmission shaft can be connected and the wheel hub can be driven to rotate in one direction. The bevel gear unit can be used in common with the components of the shaft drive system on the market. While maintaining the required speed ratio, it can effectively reduce the volume and also reduce the weight.

Description

Technical Field

[0001] The present invention relates to a bevel gear device for a drive shaft, and more particularly to a bevel gear device for a drive shaft of a bicycle. Background Art

[0002] Traditional bicycles are equipped with a chain and a sprocket to drive the bicycle body forward. Refer to Figure 1 , in recent years, there is a design that uses a drive shaft 91 and a gear 92 in combination. The drive shaft 91 cooperates with the gear 92 to drive a hub 93 of the bicycle. Among them, the drive shaft 91 has a gear portion 911 that meshes with the gear 92. When the drive shaft 91 is driven to rotate by a transmission element such as a crank of the bicycle, the hub 93 can be driven to rotate through its gear portion 911 and the gear 92, so as to achieve the purpose of moving the bicycle body forward, thereby replacing the traditional chain and sprocket. However, the gear 92 generally needs to be equipped with a locking structure to cooperate with the hub 93. Therefore, the gear 92 needs to have a certain volume, and the larger the volume, the heavier the weight, which not only increases the manufacturing cost but also increases the overall weight. Therefore, in this case, research and improvement are carried out on the gear 92 element used in combination with the drive shaft 91. Summary of the Invention

[0003] The purpose of the present invention is to provide a bevel gear device for a drive shaft that can overcome at least one drawback of the prior art.

[0004] The bevel gear device of the drive shaft of the present invention is suitable for connecting the drive shaft of a bicycle to a hub. The hub is sleeved on a shaft rod of the bicycle. The bevel gear device of the drive shaft includes a bevel gear unit and a dry bearing unit.

[0005] The bevel gear unit has a first end and a second end opposite to each other, a bevel gear located at the first end and adapted to mesh with the drive shaft, and a one-way drive coupling group located at the second end and adapted to drive the hub to rotate in one direction. The ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear is 0.164 - 0.24. The dry bearing unit is installed inside the bevel gear unit and is used to make the bevel gear unit rotate smoothly.

[0006] Furthermore, the bevel gear unit includes a sleeve having the first end and the second end. The one-way drive coupling group has several grooved surfaces or several ratchet teeth. The sleeve, the bevel gear and the grooved surfaces are connected as a whole, or the sleeve, the bevel gear and the ratchet teeth are connected as a whole.

[0007] Furthermore, the bevel gear unit includes a mandrel having the first end, and a mounting seat for the mandrel to pass through and having the second end. The bevel gear is formed on the mandrel, and the one-way drive coupling group is located on the mounting seat.

[0008] Furthermore, the mounting base has a surrounding wall that defines a mounting space for the mandrel to extend into. The surrounding wall has an inner peripheral surface surrounding the mandrel and an outer peripheral surface opposite to the inner peripheral surface, and at least one threaded hole is formed in the surrounding wall that extends from the outer peripheral surface to the inner peripheral surface and communicates with the mounting space. The bevel gear unit further includes at least one fixing member that is locked into the at least one threaded hole to fix the mounting base and the mandrel together.

[0009] Furthermore, the one-way drive coupling group has several ratchet teeth.

[0010] Furthermore, the one-way drive coupling group has several pawls.

[0011] Furthermore, it further includes an end cap that is adjacent to the first end of the bevel gear unit and is used to position the relative position between the bevel gear unit and the hub.

[0012] Furthermore, the hub includes a body portion having an end face, and a shaft portion that axially extends from the end face of the body portion and surrounds the shaft rod. The bevel gear unit is adapted to be sleeved on the shaft portion. The dry bearing unit includes a first bearing and a second bearing that sleeve the shaft portion. The first bearing has a blocking portion that separates the end face and the bevel gear unit, and the second bearing separates the bevel gear unit and the shaft portion.

[0013] Furthermore, the ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear is 0.188 to 0.237.

[0014] Furthermore, the number of teeth of the bevel gear of the bevel gear unit is 14 to 24.

[0015] Furthermore, the number of teeth of the bevel gear of the bevel gear unit is 15 to 20.

[0016] Furthermore, the sleeve includes a main body section having the second end, and a mandrel section that connects the main body section and has an outer diameter smaller than that of the main body section. The mandrel section has the first end, and the bevel gear is fixed to the mandrel section.

[0017] The efficacy of the present invention lies in that: by respectively arranging the bevel gear and the one-way drive coupling group at two opposite ends of the bevel gear unit, the transmission shaft can be connected and the hub can be driven to rotate unidirectionally. With the limitation of the ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear, it meets the required transmission ratio and the size of the bevel gear structure. Therefore, the bevel gear unit can not only be used in common with the shaft drive system components on the market, but also effectively reduce the volume and weight while maintaining the required speed ratio. The dry bearing unit enables the present invention to achieve the function of installing the bevel gear unit without additionally designing a locking structure or component, and enables the bevel gear unit to rotate smoothly. The bevel gear unit can also smoothly drive the hub to rotate, resulting in good power transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein:

[0019] Figure 1 is a perspective view showing a known transmission shaft and a gear;

[0020] Figure 2 is a perspective combination view of a first embodiment of the bevel gear device of the transmission shaft of the present invention;

[0021] Figure 3 is an exploded perspective view of the first embodiment;

[0022] Figure 4 is an incomplete sectional combination view of the first embodiment;

[0023] Figure 5 is an exploded perspective view of a second embodiment of the bevel gear device of the transmission shaft of the present invention;

[0024] Figure 6 is an incomplete sectional combination view of the second embodiment; and

[0025] Figure 7 is an exploded perspective view of some components of a third embodiment of the bevel gear device of the transmission shaft of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

[0027] Referring to Figure 2 、 3 、4, a first embodiment of the bevel gear device of the transmission shaft 11 of the present invention is applicable to connect the transmission shaft 11 of a bicycle to a wheel hub 12. One end of the transmission shaft 11 is adjacent to a crank (not shown) of the bicycle, and the other end thereof is away from the crank and has a coupling portion 111. The coupling portion 111 includes a bevel gear 112. The wheel hub 12 includes a body portion 121 and a shaft portion 122. Wherein, the body portion 121 has an end face 123 and several ratchet teeth 124. The shaft portion 122 axially extends from the end face 123 of the body portion 121. The bicycle further includes a shaft rod 13 which is assembled on the rear frame, and the wheel hub 12 is sleeved on the shaft rod 13 and can rotate relative to the shaft rod 13. The body portion 121 and the shaft portion 122 of the wheel hub 12 surround the shaft rod 13. The bevel gear device includes a bevel gear unit 2, a dry bearing unit 3, and an end cap 4.

[0028] The bevel gear unit 2 is adapted to be assembled and combined with the hub 12, and includes a sleeve 21 having opposite a first end 201 and a second end 202, a bevel gear 22 located at the first end 201 and adapted to engage the engaging portion 111 of the transmission shaft 11, and a one-way transmission coupling group 23 located at the second end 202 and adapted to drive the hub 12 to rotate in a one-way manner.

[0029] Wherein, the sleeve 21 axially penetrates through the shaft portion 122 of the hub 12 and has an inner peripheral surface 211 surrounding the shaft portion 122. The number of teeth of the bevel gear 22 is matched with the number of teeth of the bevel gear 112 of the engaging portion 111. The number of teeth of the bevel gear 22 is preferably 14 to 24, more preferably 15 to 20. The size of the bevel gear 22 generated by the results within this range, in combination with the number of teeth, module, and speed ratio that can be matched, can present an optimal combination. By means of the appropriate number of teeth of the bevel gear 22, the required transmission ratio can be provided. Preferably, the ratio of the diameter d1 of the shaft rod 13 to the maximum outer diameter d2 of the bevel gear 22 (i.e., d1 / d2) is 0.164 to 0.24, more preferably, the ratio is 0.188 to 0.237. By means of the above ratio and the design of the number of teeth of the bevel gear 22, the maximum outer diameter of the bevel gear 22 is smaller than the maximum outer diameter of the existing bevel gear assembled at this location. Therefore, the overall volume of the bevel gear unit 2 of the present invention is small and the weight is light.

[0030] The one-way transmission coupling group 23 has a plurality of groove surfaces 232 formed on the outer peripheral surface of the sleeve 21 and respectively defining a groove 230, and a plurality of pawls 231 arranged at equal angular intervals and respectively mounted on the groove surfaces 232. The pawls 231 are adapted to engage with the ratchet teeth 124 of the hub 12 to drive the hub 12 to rotate only in the one-way direction that makes the bicycle move forward. It is worth mentioning that when the present invention is implemented, the positions of the pawls and the ratchet teeth can be interchanged. That is to say, the body portion 121 of the hub 12 can be provided with a plurality of pawls, and the one-way transmission coupling group 23 has a plurality of ratchet teeth formed on the sleeve 21. At this time, the sleeve 21, the bevel gear 22 and the ratchet teeth can be connected into a whole. On the other hand, the ratchet teeth can also form a component and be assembled on the sleeve 21. In this way, the one-way transmission coupling group 23 can also drive the hub 12 in a one-way manner.

[0031] It is worth mentioning that the sleeve 21, the bevel gear 22 and the groove surfaces 232 of the bevel gear unit 2 of the first embodiment are connected into a whole, and the pawls 231 are installed in the grooves 230. Therefore, the coaxiality of the components is good.

[0032] The dry bearing unit 3 is installed within the bevel gear unit 2 and includes a first bearing 31 and a second bearing 32 that annularly surround the shaft portion 122 of the hub 12. The first bearing 31 is disposed at the end face 123 of the body portion 121 and the inner circumferential surface 211 of the sleeve 21, and has a stop portion 311 located on the end face 123. The stop portion 311 separates the end face 123 from the bevel gear unit 2. The second bearing 32 is located between the shaft portion 122 of the hub 12 and the inner circumferential surface 211 of the sleeve 21 to separate the shaft portion 122 from the bevel gear unit 2. By means of the dry bearing unit 3, the bevel gear unit 2 can rotate smoothly after being driven. Moreover, the advantage of using a dry bearing instead of other types of bearings (such as ball bearings) is that the dry bearing has a small structure and can be matched with the bevel gear unit 2 of the present invention, which has a small volume and outer diameter, and is suitable for use in a precision and small-scale device such as a bicycle. The dry bearing has good self-lubricity and is a grease-free bearing, which is convenient to use.

[0033] The end cap 4 is coupled near the first end portion 201 of the bevel gear unit 2 and annularly surrounds the shaft portion 122 of the hub 12 to position the relative position between the bevel gear unit 2 and the hub 12, so that after the bevel gear unit 2 is sleeved on the shaft portion 122, it will not be displaced due to shaking during operation, so as to avoid affecting the transmission efficiency.

[0034] During use, the user steps on and rotates the pedal of the bicycle in the forward direction, and drives the transmission shaft 11 to rotate about its own central axis through the crank, and then can drive the bevel gear unit 2 to rotate through the bevel gear 112 of the coupling portion 111, thereby driving the hub 12 to rotate, so as to achieve the purpose of driving the bicycle forward. When the user steps on and rotates the pedal in the backward direction, although the bevel gear unit 2 will be driven to rotate in the reverse direction, because the pawl 231 of the one-way transmission coupling group 23 is matched with the ratchet teeth 124 of the hub 12, the bevel gear unit 2 will only rotate idly and will not drive the hub 12 to rotate, nor will it cause the bicycle to move backward.

[0035] In summary, by providing the bevel gear 22 and the one-way drive coupling group 23 at two opposite ends of the bevel gear unit 2 respectively, on one hand, the bevel gear 22 is connected to the transmission shaft 11, and on the other hand, the one-way drive coupling group 23 drives the hub 12 to rotate unidirectionally. Moreover, since the pawls 231 of the one-way drive coupling group 23 and the ratchet teeth 124 of the hub 12 are of the same general specification as those of the shaft drive system of ordinary bicycles, the bevel gear device can be directly assembled onto the commercially available and general-purpose hub 12. Therefore, there is no need to specially develop special-specification wheel sets or other parts. With the bevel gear 22 having an appropriate number of teeth, and the ratio of the diameter of the shaft rod 13 to the maximum outer diameter of the bevel gear 22 being limited, it meets the required transmission ratio and the structural size of the bevel gear 22 of the present invention, enabling the present invention to effectively reduce the volume and also reduce the weight while maintaining the required speed ratio. The dry bearing unit 3 enables the present invention to achieve the function of installing the bevel gear unit 2 without additionally designing a locking structure or component, enabling the bevel gear unit 2 and the hub 12 to be firmly combined and enabling the bevel gear unit 2 to rotate smoothly. The bevel gear unit 2 can also smoothly drive the hub 12 to rotate, resulting in excellent power transmission efficiency.

[0036] Refer to Figure 5 、 6 , a second embodiment of the bevel gear device of the transmission shaft of the present invention is substantially the same in structure as the first embodiment, except that: the bevel gear unit 2 of this second embodiment is assembled from several components and includes a core shaft 24 having the first end portion 201, a mounting seat 25 for the core shaft 24 to penetrate and fit into and having the second end portion 202, and several fixing members 26. The bevel gear 22 is formed at the first end portion 201 of the core shaft 24, and the one-way drive coupling group 23 is located at the second end portion 202 of the mounting seat 25. Among them, the mounting seat 25 has a surrounding wall 251 defining a mounting space 250 for the core shaft 24 to extend into. The surrounding wall 251 has an inner peripheral surface 252 surrounding the core shaft 24 and an outer peripheral surface 253 opposite to the inner peripheral surface 252, and the surrounding wall 251 is formed with several screw holes 254 extending from the outer peripheral surface 253 to the inner peripheral surface 252 and communicating with the mounting space 250. The fixing members 26 are screws and are respectively locked in through the screw holes 254, and one end of the fixing member 26 abuts against the surface of the core shaft 24 to fix the core shaft 24 and the mounting seat 25.

[0037] In this second embodiment, by assembling and combining the two components of the core shaft 24 and the mounting seat 25, and the bevel gear 22 and the one-way drive coupling group 23 are respectively provided on the core shaft 24 and the mounting seat 25, it can also be used to connect the transmission shaft 11 ( Figure 2 ) and the hub 12, achieving the same effect as the first embodiment. Moreover, due to the advantages of easy processing and mass production of the two-piece components, during manufacturing, the core shaft 24 can be easily positioned by a jig to form the bevel gear 22.

[0038] Refer to Figure 7 , a third embodiment of the bevel gear device of the transmission shaft of the present invention is substantially the same in structure as the first embodiment, except that: the sleeve 21 of this third embodiment includes a main body section 212 and a mandrel section 213 that extends forward from the main body section 212 and has an outer diameter smaller than that of the main body section 212. The main body section 212 has the second end portion 202, and the mandrel section 213 has the first end portion 201. The bevel gear 22 is fixed to the mandrel section 213 of the sleeve 21 by means of a tight fit.

[0039] However, the above are only embodiments of the present invention, and the scope of implementation of the present invention cannot be limited thereby. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification still fall within the scope covered by the patent of the present invention.

Claims

1. A bevel gear device for a drive shaft, suitable for connecting the drive shaft of a bicycle to a wheel hub. The wheel hub is sleeved on a shaft rod of the bicycle. The wheel hub includes a body portion having an end face, and a shaft portion axially extending from the end face of the body portion and surrounding the shaft rod. It is characterized in that, The bevel gear device of the transmission shaft includes: A bevel gear unit adapted to be sleeved on the shaft portion. The bevel gear unit has an opposite first end and a second end, a bevel gear located at the first end and adapted to mesh with the transmission shaft, and a one-way drive coupling group located at the second end and adapted to drive the hub to rotate in one direction. The ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear is 0.164 to 0.24; and A dry bearing unit installed in the bevel gear unit and used to make the bevel gear unit rotate smoothly. The dry bearing unit includes a first bearing and a second bearing that sleeve the shaft portion. The first bearing has a blocking portion that separates the end face from the bevel gear unit, and the second bearing separates the bevel gear unit from the shaft portion.

2. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The bevel gear unit includes a sleeve having the first end and the second end. The one-way drive coupling group has several groove surfaces or several ratchet teeth. The sleeve, the bevel gear and the groove surfaces are connected as a whole, or the sleeve, the bevel gear and the ratchet teeth are connected as a whole.

3. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The bevel gear unit includes a mandrel having the first end, and a mounting seat for the mandrel to penetrate and sleeve into and having the second end. The bevel gear is formed on the mandrel, and the one-way drive coupling group is located on the mounting seat.

4. The bevel gear device of the transmission shaft according to claim 3, characterized in that, The mounting seat has a surrounding wall that defines a mounting space for the mandrel to extend into. The surrounding wall has an inner peripheral surface surrounding the mandrel and an outer peripheral surface opposite to the inner peripheral surface, and at least one screw hole is formed in the surrounding wall that extends from the outer peripheral surface to the inner peripheral surface and communicates with the mounting space. The bevel gear unit further includes at least one fixing member locked through the at least one screw hole to fix the mounting seat and the mandrel.

5. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The one-way drive coupling group has several ratchet teeth.

6. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The one-way drive coupling group has several pawls.

7. The bevel gear device of the transmission shaft according to claim 1, characterized in that, It further includes an end cover adjacent to the first end of the bevel gear unit and used to position the relative position between the bevel gear unit and the hub.

8. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The ratio of the diameter of the shaft rod to the maximum outer diameter of the bevel gear is 0.188 to 0.

237.

9. The bevel gear device of the transmission shaft according to claim 1, characterized in that, The number of teeth of the bevel gear of the bevel gear unit is 14 to 24.

10. The bevel gear device of the transmission shaft according to claim 8 or 9, characterized in that, The number of teeth of the bevel gear of the bevel gear unit is 15 to 20.

11. The bevel gear device of the transmission shaft according to claim 2, wherein, The sleeve includes a main body section having the second end, and a mandrel section connected to the main body section and having an outer diameter smaller than that of the main body section. The mandrel section has the first end, and the bevel gear is fixed to the mandrel section.

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