Abstract:
A bicycle hub comprises: a housing, a driving base in the housing, and an engaging unit for the driving base to drive the housing in a single direction. The engaging unit consists of several claws and elastic elements surrounding thereon. Each of the elastic elements is an arc hook and urges against the corresponding claw. The claws thus enable the driving base to drive the housing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to a bicycle hub and, in particular, to a bicycle hub that is easy to assembled and maintained and has a very good transmission effect. 
     2. Related Art 
     A conventional hub transmission structure, as shown in  FIG. 10 , mainly consists of a housing  91  and a chain wheel base  93  connected inside the housing  91 . The housing  91  has an inner hole  94  whose inner ring surface is formed with a ratchet ring  95 . One end part of the chain wheel base  93  is accommodated in the inner hole  94  of the housing  91 . The end part has a claw base  96 . The claw base  96  is elastically pressed by a ring spring  97 , pushing a plurality of claws  98  against the claw base  96 . One end of each of the claws  98  is elastically pressed by the ring spring  97  so that its other end rises and matches with the ratchet ring  95  of the housing  97 . The chain wheel base  93  is thus only allowed to drive the housing  91  in a single direction. 
     However, the above-mentioned hub transmission structure relies on the ring spring  97  to fix the claws  98  on the claw base  96 . Therefore, once the ring spring  97  has elasticity fatigue or some deformation, as shown in  FIG. 11 , the forces imposed on the claws  98  become uneven. The claws  98  and the ratchet ring  95  cannot engage firmly, and the transmission efficiency is greatly reduced. The problem can be as serious as sliding. Moreover, to replace the ring spring  97  or if one of the claws  98  breaks, all the claws  98  will be released immediately after the user removes the ring spring  97 . This is because they are originally positioned by the ring spring  97 . So the user needs to re-assemble all the claws  98  in each replacement. This is very inconvenient for maintenance. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide a bicycle hub that is easy to assemble and maintain and has a very good transmission effect. 
     To achieve the above-mentioned objective, the invention provides a bicycle hub that includes a housing, a driving base, and an engaging unit. One end of the housing is formed with an inner hole that has a ratchet ring on its inner ring surface. One end of the driving base is mounted in the inner hole of the housing to rotate with respect to the housing. The end of the driving base in the inner hole has several annular accommodating grooves on its outer surface. The engaging unit has several claws in the corresponding accommodating grooves and an elastic element around each of the claws to urge it against the ratchet ring. 
     The claw has a pivotal part to be inserted in the accommodating groove and an engaging part that is opposite to the pivotal part and engages with the ratchet ring. The engaging part of the claw can swing from a first position that engages with the ratchet ring to a second position away from the ratchet ring, using the pivotal part as the axis. The claw is further formed with a groove extending along the rotational direction of the driving base, defining an acting end and a limiting end. The elastic element is an arc hook, with its one end connected to the side of the accommodating groove and its other end extending and catching the groove of the claw to press on the acting end of the claw groove, so that the engaging part of the claw rises up. The limiting end of the claw groove is stopped by the elastic element to restrict the rising angle of the engaging part. The engaging part swings to the first position and engages with the ratchet ring in one direction. 
     The invention further provides another bicycle hub that includes a housing, a driving base, and an engaging unit. One end of the housing has an inner hole with a plurality of annular accommodating grooves on its inner ring surface. The driving base is mounted in the inner hole of the housing its one end to rotate with respect to the housing. The outer surface of the end of the driving base in the inner hole has a ratchet ring. The engaging unit has a plurality of claws installed in the accommodating grooves and an elastic element surrounding the corresponding claw to urge the claw against the ratchet ring. 
     Each of the claws has a pivotal part to be put in the corresponding accommodating groove and an engaging part opposite to the pivotal part and matching with the ratchet ring. The engaging part of the claw swings from a first position matching with the ratchet ring to a second position away from the ratchet ring, using the pivotal part as an axis. The claw further has a groove extending along the rotational direction of the driving base, defining an acting end and a limiting end. The elastic element is an arc hook, with its one end connected to the side of the accommodating groove and its other end extending and catching the groove of the claw to press on the acting end of the claw groove, so that the engaging part of the claw rises up. The limiting end of the claw groove is stopped by the elastic element to restrict the rising angle of the engaging part; and the engaging part swings to the first position and engages with the ratchet ring in one direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein: 
         FIG. 1  is a three-dimensional view of the first embodiment of the invention; 
         FIG. 2  is a local exploded view of the first embodiment; 
         FIG. 3  is a schematic view of the first embodiment after it is assembled; 
         FIG. 4  is a schematic view of the first embodiment in use, showing the state when the driving base drives the housing; 
         FIG. 5  is a schematic view of the first embodiment in use, showing the state when the driving base rotate in reverse alone; 
         FIG. 6  is a schematic view of the second embodiment of the invention; 
         FIG. 7  is a three-dimensional exploded view of the third embodiment of the invention; 
         FIG. 8  is a schematic view of the third embodiment after it is assembled; 
         FIG. 9  is a schematic view of the third embodiment in use, showing the state when the engaging part of the claw swings to the second position; 
         FIG. 10  is a schematic view of a conventional hub transmission structure; 
         FIG. 11  is a schematic view of the conventional hub transmission structure when its ring spring is broken. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     Please refer to  FIGS. 1 to 5  for a first embodiment of the disclosed bicycle hub. It mainly consists of a housing  11 , a driving base  21  disposed in the housing  11 , and an engaging unit  31  for the driving base  21  to drive the housing  11  in a single direction. 
     One end of the housing  11  is formed with an inner hole  12 . The inner ring surface of the inner hole  12  is formed with a ratchet ring  13 . 
     One end part  22  of the driving base  21  is mounted in the inner hole  12  of the housing  11 . The driving base  21  is driven by a bicycle chain (not shown) to rotate. The end  22  of the driving base  21  in the inner hole  12  has several accommodating grooves  23  along the annular direction on its outer surface. Each of the accommodating grooves  23  consists of a bottom part  231 , a limiting part  232 , and an opening  233 . The outer surface of the end part  22  further has a notch  24  in the annular direction and cutting through the openings  233  of the accommodating grooves  23 . 
     The engaging unit  31  is comprised of several claws  32  disposed in the corresponding accommodating grooves  23  and an elastic element  33  around each of the claws  32  to urge the corresponding claw  32  against the ratchet ring  13 . Each of the claws  32  has a pivotal part  321  for the accommodating groove  23  and an engaging part  32  opposite to the pivotal part  321  and engaging with the ratchet ring  13 . The engaging part  322  of the claw  32  can swing from a first position  41  engaging with the ratchet ring  13  to a second position  42  away from the ratchet ring  13 , using the pivotal part  321  as an axis. The claw  32  is further formed with a groove  34  extending along the rotational direction of the driving base  21  and connecting with the notch  24  on the end part  22  of the driving base  21 . The groove  34  is defined with an acting end  341  and a limiting end  342 . The elastic element  33  is an arc hook. One end of the elastic element  33  connects to the notch  24  of the accommodating groove  23  near the limiting part  232 . The other end extends and catches the groove  34  of the claw  32 , pressing against the acting end  341  of the groove  34  of the claw  32 . The engaging part  322  of the claw  32  thus rises. The limiting end  342  of the groove  34  of the claw  32  is stopped by the elastic element  33  to restrict the rising angle of the engaging part  322  of the claw  32 . The engaging part  322  of the claw  32  can thus swing to the first position  41 , maintaining a single-direction engagement with the ratchet ring  13  all the time. 
     Please refer to  FIG. 4 . After the disclosed bicycle hub is assembled, the pivotal part  321  of each of the claws  32  is exactly disposed in the groove bottom part  231  of the corresponding accommodating part  23 . Each of the elastic elements  33  catches the groove  34  of the claw  32 , imposing a pressure on the acting end  341  thereof. The engaging part  322  of each of the claws  32  thus swings upward to the first position  41 . In this case, the engaging parts  322  of the claws  32  penetrate out of the openings  233  of the accommodating grooves  23 , correspondingly engaging the ratchet ring  13  of the housing  11 . Since the limiting end  342  of the groove  34  of each of the claws  32  also rises and touches against the elastic element  33 , the rising angle of the engaging parts  322  of the claws  32  is restricted. When the driving base  21  is driven to rotate counterclockwise, the single-direction engagement between the claws  32  and the ratchet ring  13  drives the housing  11  to rotate along. 
     On the other hand, when the driving base  21  is driven to rotate clockwise, as shown in  FIG. 5 , the engaging part  322  of the claw  32  on the driving base  21  is urged by the ratchet ring  13  to push the acting end  341  of the claw  32  upward to urge against the elastic element  33 . The engaging part  322  of the claw  32  thus swings from the first position  41  to the second position  42  away from the ratchet ring  13 . Afterwards, the resilient restoring force of the elastic element  33  brings the claws  32  to engage with the ratchet ring  13  again. This mechanism allows the driving base  21  to rotate in reverse alone without rotating the housing  11 . Therefore, the invention can achieve the expected transmission effect. 
     Please refer to  FIG. 6  for a second embodiment of the disclosed bicycle hub. It differs from the first embodiment in that the elastic element  33 B is connected to the sidewall of the accommodating groove  23  using its one end. Its other end extends and catches the groove  34  of the claw  32 , pressing against the acting end  341  thereof. The engaging part  322  of the claw  32  can also swing to the first position  41  to maintain the single-direction engagement with the ratchet ring  13 . When the acting end  341  of the groove  34  of the claw  32  is urged by the elastic element  33 B, its limiting end  342  also rises, also restricted by the elastic element  33 B. As a result, the rising angle of the engaging parts  322  of the claws  32  is fixed as before. 
       FIGS. 7 to 9  show a third embodiment of the disclosed bicycle hub. It mainly includes a housing  11 C, a driving base  21 C disposed in the housing  11 C, and an engaging unit  31 C for the driving base  21 C to drive the housing  11 C in a single direction. 
     One end of the housing  11 C is formed with an inner hole  12 C. The inner ring surface of the inner hole  12 C has several annular accommodating grooves  13 C, each of which consists of a groove bottom part  131 C, a limiting part  132 C, and an opening  1330 . The inner ring surface of the inner hole  12 C is further formed with a notch  14 C along the annular direction and cutting through the openings  133 C of the accommodating grooves  13 C. 
     One end part  22 C of the driving base  21 C is mounted in the inner hole  12 C. The driving base  21 C is driven by a bicycle chain (not shown) to rotate with respect to the housing  11 C. The end part  22 C of the driving base  21 C in the inner hole  12 C has a ratchet ring  23 C on its outer surface. 
     The engaging unit  31 C has several claws  32 C to be disposed in the corresponding accommodating grooves  13 C and an elastic element  33 C for each of the claws  32 C to urge against the ratchet ring  23 C. The claw  32 C has a pivotal part  321 C for the accommodating groove  13 C and an engaging part  322 C opposite to the pivotal part  321 C and engaging with the ratchet ring  23 C. The engaging part  322 C of the claw  32 C can swing from a first position  41  engaging with the ratchet ring  23 C to a second position  42  away from the ratchet ring  23 C, using the pivotal part  321 C as the axis. The claw  32 C is further formed with a groove extending along the rotational direction of the driving base  21 C. The groove  34 C is defined with an acting end  341 C and a limiting end  342 C. The elastic element  33 C is an arc hook, with its one end connected to the notch  14 C of the accommodating groove  13 C near the limiting part  132 C and its other end extending and catching the groove  34 C of the claw  32 C, pressing upon the acting 3nd  341 C of the groove  34 C of the claw  32 C. The engaging part  322 C of the claw  32 C thus rises. The limiting end  342 C of the groove  34 C of the claw  32 C is stopped by the elastic element  33 C to constrain the rising angle of the engaging part  322 C of the claw  32 C. The engaging part  322 C of the claw  32 C thus swings to the first position  41  and maintains its single-direction engagement with the ratchet ring  23 C. 
     In practice, as the third embodiment of the disclosed bicycle hub runs, each of the elastic elements  33 C catches the groove  34 C of the corresponding claw  33 C and generates a pressing force on the acting end  341 C of the groove  34 C. The engaging part  322 C of each claw  32 C swings upward to the first position  41 . In this case, the engaging parts  322 C of the claws  32 C penetrate through the openings  133 C of the accommodating grooves  13 C, and correspondingly engage with the ratchet ring  23 C of the driving base  21 C. The limiting ends  342 C of the grooves  34 C of the claws  32 C also rise to touch against the elastic elements  33 C. This constrains the rising angle of the engaging parts  322 C of the claws  32 C to a fixed value. When the driving base  21 C is driven by a force, the single-direction engagement between the claws  32 C and the ratchet ring  23 C drives the housing  11 C to rotate along. This achieves the expected transmission effect. 
     The disclosed bicycle hub has the following advantages: 
     1. Each of the claws in the invention has an elastic element. Even if one of the elastic elements or claws is broken, the rest claws can still engage with the ratchet ring normally. The invention thus does not slide. 
     2. The acting end and the limiting end in the groove of the claw are defined such that when the elastic element presses on the acting end, the limiting end of the claw groove is stopped by the elastic element to restrict the rising angle of the claw. Therefore, it is not necessary to provide additional stopping blocks in the accommodating grooves. The disclosed claws can still maintain a fixed rising angle. This greatly simplifies the structure of the hub and reduces its production cost. Moreover, the rising angle of the claws is fixed, making the assembly of the disclosed hub much easier. 
     3. Each of the claws has a corresponding elastic element. Therefore, one can simply replace any damaged elastic element or claw. This makes the maintenance quicker and easier. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to people skilled in the art. Therefore, it is contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.