Patent Publication Number: US-2004055413-A1

Title: Crank set having a pedal unit adapted to be pivoted to a crank arm without directional restriction

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a crank set, more particularly to a crank set having a pedal unit that is adapted to be pivoted to a crank arm without directional restriction.  
       [0003] 2. Description of the Related Art  
       [0004] Referring to FIG. 1, a conventional bicycle crank set is shown to include a pair of crank arms  20  and a pair of pedal units  30 . Each crank arm  20  has an axle-mounting end  23  mounted securely on a chain sprocket  25  for co-rotation therewith, and a pedal-connecting end  22  that is formed with an internally threaded hole  21  extending in a transverse direction relative to a longitudinal direction of the crank arm  20 . Each pedal unit  30  is disposed at one side of a respective one of the crank arms  20 , and includes a pedal shaft  10  and a pedal body  30 ″ pivoted to the pedal shaft  10  so as to permit rotation of the pedal body  30 ″ about the pedal shaft  10 . The pedal shaft  10  has a threaded portion  11  threadedly inserted into the internally threaded hole  21  in the pedal-connecting end  22  of the crank arm  20 .  
       [0005] One disadvantage of the aforesaid conventional crank set resides in that the thread of the threaded portion  11  of the pedal shaft  10  of each pedal unit  30  is required to be directional such that rotation of the crank arms  20  in a forward direction by an external force applied on the pedal units  30  will not result in loosening of the threaded portion  11  with respect to the internally threaded hole  21 . For instance, if the threaded portion  11  is turned in the same direction as the forward direction for tightening in the internally threaded hole  21 , forward rotation of the crank arms  20  will result in loosening of the threaded portion  11  due to holding of the pedal units  30  by the applied external force. As a consequence, manufacture and assembly of the conventional crank set is relatively inconvenient.  
       SUMMARY OF THE INVENTION  
       [0006] Therefore, the object of this invention is to provide a crank set having a pedal unit adapted to be pivoted to a crank arm without directional restriction so as to eliminate the aforesaid disadvantage associated with the prior art.  
       [0007] Accordingly, a crank set according to the present invention includes: a crank arm extending in a longitudinal direction, and having two opposite sides and a pedal-connecting end that is formed with a through hole extending in a transverse direction relative to the longitudinal direction; and a pedal unit disposed at one of the opposite sides of the crank arm, and including a pedal shaft and a pedal body pivoted to the pedal shaft so as to permit rotation of the pedal body about the pedal shaft. The pedal shaft has a crank-connecting end that projects outwardly from the pedal body into the through hole in the pedal-connecting end of the crank arm and that is formed with an internally threaded hole. A headed bolt is disposed at the other one of the opposite sides of the crank arm, and extends into and threadedly engages the internally threaded hole in the crank-connecting end of the pedal shaft so as to prevent disengagement of the pedal unit from the crank arm. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which:  
     [0009]FIG. 1 is an exploded view of a conventional bicycle crank set shown together with a chain sprocket;  
     [0010]FIG. 2 is an exploded view of the preferred embodiment of a bicycle crank set according to the present invention;  
     [0011]FIG. 3 is an assembled perspective view of the preferred embodiment according to the prevent invention;  
     [0012]FIG. 4 is a sectional view of the preferred embodiment taken along lines IV-IV in FIG. 3; and  
     [0013]FIG. 5 is an exploded view of a modified preferred embodiment of this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0014] Before the present invention is described in greater detail with reference to the following preferred embodiments, it should be noted that same reference numerals have been used to denote similar elements throughout the specification.  
     [0015] Referring to FIGS.  2  to  4 , the preferred embodiment of a bicycle crank set according to the present invention is adapted to be mounted on a crank axle of a chain sprocket (not shown) , and is shown to include a crank arm  40 , a pedal unit  50 , and a headed bolt  80 .  
     [0016] As illustrated, the crank arm  40  extends in a longitudinal direction, and has two opposite sides and a pedal-connecting end  41  that is formed with a through hole  60  extending in a transverse direction relative to the longitudinal direction.  
     [0017] The pedal unit  50  is disposed at one of the opposite sides of the crank arm  40 , and includes a pedal shaft  70  and a pedal body  51  pivoted to the pedal shaft  70  so as to permit rotation of the pedal body  51  about the pedal shaft  70 . The pedal shaft  70  has a crank-connecting end  71  that projects outwardly from the pedal body  51  into the through hole  60  in the pedal-connecting end  41  of the crank arm  410  and that is formed with an internally threaded hole  72 .  
     [0018] The headed bolt  80  is disposed at the other of the opposite sides of the crank arm  40 , extends into and threadedly engages the internally threaded hole  72  in the crank-connecting end  71  of the pedal shaft  70  so as to prevent disengagement of the pedal unit  50  from the crank arm  40 .  
     [0019] Note that since the pedal shaft  70  extends through the through hole  60  in the crank arm  40  to engage the headed bolt  80 , the direction of the thread formed on the internally threaded hole  72  in the pedal shaft  70 , and the direction of the thread formed on the headed bolt  80  are not required to be restricted in the clockwise or counterclockwise directions, thereby eliminating the aforesaid disadvantage of the prior art.  
     [0020] Referring to FIG. 5, a modified preferred embodiment of a bicycle crank set according to the present invention is shown to be similar to the previous embodiment in construction. The main difference resides in that the through hole  60  in the pedal-connecting end  41  of the crank arm  40  has a polygonal cross-section. The crank-connecting end  71  of the pedal shaft  70  thus has a polygonal cross-section that complements the through hole  60  in the crank arm  40 .  
     [0021] With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that the invention be limited only as indicated in the appended claims.