Abstract:
A pivot assembly for coupling a treadle with a bicycle crank is disclosed. The pivot assembly includes a circular seat for being coupled with the crank. Each of two buckle rings received in the circular seat uses a wedge to engage with a connecting shaft of the treadle. By pressing the two buckle rings inward, the wedges leave the connecting shaft so the treadle can be assembled to or disassembled from the crank.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to bicycle parts, and more particularly, to a pivot assembly for coupling a treadle with a bicycle crank. The pivot assembly is easy to assemble and disassemble so as to benefit bicycle manufacturers by reducing assembling time and so as to allow a bicycle user to easily change treadles by himself/herself without using additional tools. 
         [0003]    2. Description of Related Art 
         [0004]    A known device for coupling a treadle with a bicycle crank can be seen in  FIG. 1 . The known device comprises a treadle shaft  11  to be combined with a treadle  10  and a connector  21  to be combined with a bicycle crank  20 . The treadle  10  is designed to revolve on the treadle shaft  11  freely and the connector  21  has one end provided with a threaded segment  22  for being coupled with a threaded hole  23  formed on the crank  20 . The connector  21  has an opposite end formed with a hole  24  for receiving the treadle shaft  11 , wherein a wall defining the hole  24  is provided with a plurality of balls  25  that are annularly arranged. The balls  25  are controlled by a controlling ring  26  attached to an exterior of the connector  21  for moving toward or away an axis of the connector  21 . When moving toward the axis of the connector  21 , each said ball  25  partially projects from the hole  24  and gets coupled with a corresponding ball recess  12  formed on the treadle shaft  11 , so that the treadle shaft  11  is combined with the connector  21 . When moving away the axis of the connector  21 , each said ball  25  no more exposes in the hole  24  and leaves the corresponding ball recess  12 , so that the treadle shaft  11  is free from the engagement with the connector  21 . 
         [0005]    The conventional connector  21  composed of tiny springs, recesses, rings and other positioning elements is structurally complicated and difficult to assemble. Nevertheless, a defective connector  21  can significantly increase time consumption of bicycle assembling process and raise failure rate of bicycle assembling process. Besides, once the treadle  10  is coupled with the crank  20 , the coupling problem between the controlling ring  26  and the balls  25  can render the treadle shaft  11  jammed in the connector  21  and the treadle  10  can be no more disassembled from the crank  20 . 
       SUMMARY OF THE INVENTION 
       [0006]    The primary objective of the present invention is to provide a pivot assembly between a treadle and a bicycle crank, wherein the pivot assembly is simple in structure and easy to use, so as to allow a bicycle user to assemble and disassemble the treadle on his/her own. When applied to a folding bicycle, the disclosed pivot assembly allows a treadle to be easily detached so as to facilitate storage of the collapsed bicycle. 
         [0007]    According to the present invention, a pivot assembly for coupling a treadle with a crank of a bicycle comprises: a circular seat, installed therein two transversely shiftable buckle rings and having two pressing blocks peripherally attached thereto for shifting the two buckle rings; and a pivot shaft, having two slots and passing through the buckle rings so that the buckle rings have wedges thereof normally engaged with the slots. Thereby, when the pressing blocks are pressed, the wedges leave the slots so as to allow a connecting shaft of the treadle to enter the pivot shaft. When the pressing blocks are released, the wedges engage with the slots again and fit in a groove formed on the connecting shaft so that the treadle and the pivot shaft are combined. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawing, wherein: 
           [0009]      FIG. 1  shows a known device for coupling a bicycle treadle with a crank; 
           [0010]      FIG. 2  is an exploded view of a pivot assembly according to the present invention; 
           [0011]      FIG. 3  shows the pivot assembly, a bicycle treadle, and a crank; 
           [0012]      FIG. 4  is a vertical sectional view of the pivot assembly; 
           [0013]      FIG. 5  is another vertical sectional view of the pivot assembly showing the pivot assembly in operation; 
           [0014]      FIG. 6  is a horizontal sectional of the pivot assembly; and 
           [0015]      FIG. 7  is another horizontal sectional view of the pivot assembly showing the pivot assembly in operation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    While a preferred embodiment provided hereinafter for illustrating the concept of the present invention as described above, it is to be understood that the components of the embodiment shown in the accompanying drawings are depicted for the sake of easy explanation and need not to be made in scale. 
         [0017]    Please refer to  FIGS. 2 ,  3 ,  4  and  6  for a pivot assembly of the present invention. The pivot assembly comprises a circular seat  10 , two buckle rings  30 , a pivot shaft  40 , two pressing blocks  50 , a semicircular spring  60 , and an annular cap  70 . 
         [0018]    The circular seat  10  has an axially extending through hole  11  and an accommodating space  12  formed in the circular seat  10 . The through hole  11  and the accommodating space  12  are intercommunicated. Two openings  13  are formed on an outer periphery of the circular seat  10  and diametrically opposite to each other and intercommunicated with the accommodating space  12 . In addition, a pair of straight inner walls  14  is formed in the circular seat  10  to flank the accommodating space  12 . 
         [0019]    Each of the two buckle rings  30  has a generally annular body  31 . The annular body  31  includes two straight outer walls  32  parallel to each other, an arched abutting portion  33  and a bar-shaped wedge  34 . A pair of bent portions  36  is formed at the border of the wedge  34  and the body  31  so that the wedge  34  is not level with the abutting portion  33  and the body  31 . The two buckle rings  30  are piled and received in the accommodating space  12  of the circular seat  10  together in the manner that one of the buckle ring  30  has its abutting portion  33  adjacent to the wedge  34  of the other buckle ring  30  while the straight outer walls  32  contacting the straight inner walls  14  of the circular seat  10 , so that the two buckle rings  30  are retained from rotating in the accommodating space  12 . 
         [0020]    The pivot shaft  40  has a threaded portion  41  and a socket portion  42  that are coaxially connected. The socket portion  42  passes through the through hole  11  and the accommodating space  12  of the circular seat  10 . Each said buckle ring  30  has an inner diameter greater than an outer diameter of the socket portion  42  so that the buckle rings  30  are allowed to transversely shift in the accommodating space  12 . The socket portion  42  of the pivot shaft  40  is peripherally formed with a first slot  43  and a second slot  44  that are diametrically opposite on the socket portion  42 . 
         [0021]    Each of the two pressing blocks  50  is an arched member having an outer side formed as an arched wall  55  matching an outer periphery of the circular seat  10  and an inner side provided with a first stair  51 , a second stair  52 , and a third stair  53 . The two pressing blocks  50  are settled in the two openings  13  of the circular seat  10 , respectively, with their first stairs  51  receiving the abutting portions  33  of the two buckle rings  30  and with their second stairs  52  abutting on the wedges  34 . 
         [0022]    The semicircular spring  60  is deposited in the circular seat  10  with two pin portions  61  thereof piercing through two holes  56 ,  35  preformed on the pressing blocks  50  and the buckle rings  30 . 
         [0023]    The annular cap  70  is coupled to the circular seat  10  in a close fit so as to position the spring  60 . 
         [0024]    Referring to  FIG. 3 , in use, the pivot assembly has its threaded portion  41  on the pivot shaft  40  coupled with a threaded hole  81  formed on a crank  80 , and has its socket portion  42  mounted around a connecting shaft  84  of the treadle  83 . The connecting shaft  84  is peripherally formed with a groove  85  that has a bottom includes at least two flat retaining planes  86 . 
         [0025]    Seeing  FIGS. 4 and 6 , the two pressing blocks  50  are normally pushed outward and jutting out of the outer periphery of the circular seat  10  by the spring  60 , so that the two buckle rings  30  are pulled outward to have the wedges  34  entering the first slot  43  and the second slot  44  and thus jutting out of the inner wall of the socket portion  42 . Consequently, the two wedges  34  jutting out of the inner wall of the socket portion  42  are received in the groove  85  so as to be abutted, and thus retained by the two retaining planes  86 . 
         [0026]    As can be seen in  FIGS. 5 and 7 , to disassemble the treadle  83 , the two pressing blocks  50  can be pressed inward so that the two buckle rings  30  shift in converse directions to make the two wedges  34  move onto the second stairs  52  of the pressing blocks  50 . At this time, the wedges  34  leaving the retaining planes  86  and the groove  85  of the connecting shaft  84  allow the treadle  83  to move away from the socket portion  42  along an axis of the connecting shaft  84 . The bent portions  36  on the relatively shifting buckle rings  30  facilitate reducing the contact area between the buckle rings  30 , thereby minimizing the abrasion of the buckle rings  30 . 
         [0027]    The present invention has been described with reference to the preferred embodiment and it is understood that the embodiment is not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.