Patent Publication Number: US-2003224891-A1

Title: Chain casing for a bicycle

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The invention relates to a chain casing, more particularly to a bicycle chain casing that includes a plurality of compartments for receiving a chain and cables of a bicycle.  
       [0003] 2. Description of the Related Art  
       [0004] Referring to FIG. 1, a conventional bicycle  20  is shown to include a chain ring  21 , a crank pedal  22  co-axially mounted to the chain ring  21 , an axle  24  disposed rearwardly of the chain ring  21 , a sprocket (not visible) mounted on the axle  24 , a chain stay (not visible) extending from the chain ring  21  to the sprocket, a chain (not visible) trained on the sprocket and the chain ring  21 , and a chain casing  23  fixed to the chain stay and extending between the sprocket and the chain ring  21  in such a manner as to enclose the chain ring  21 , the sprocket and the chain.  
       [0005] One disadvantage of the aforesaid conventional bicycle resides in that the size of the chain casing is relatively large.  
       SUMMARY OF THE INVENTION  
       [0006] The object of this invention is to provide a chain casing for a bicycle which can overcome the aforesaid drawback associated with the conventional bicycle.  
       [0007] Accordingly to one aspect of the present invention, a chain casing is adapted for use in a bicycle which includes a chain ring, a crank pedal co-axially connected to the chain ring, an axle disposed rearwardly of the chain ring, a sprocket mounted on the axle, a chain stay extending between the chain ring and the sprocket, and a chain trained on the chain ring and the sprocket, and having upper and lower chain sections. The chain casing includes an intermediate hollow body adapted to be fixed to the chain stay and adapted to extend between the chain ring and the sprocket. The intermediate hollow body has front and rear ends, a peripheral wall extending from the front end to the rear end and defining a receiving space, and a partition extending in the receiving space to divide the receiving space into upper and lower compartments that are adapted to respectively receive the upper and lower chain sections therein. A tensioning roller is disposed between the front end of the peripheral wall and the chain ring, and is adapted to be disposed below and in sliding contact with the lower claim section. The tensioning roller is straddled by the lower chain section of the chain.  
       [0008] Accordingly to another aspect of the present invention, the chain casing further includes a front shield portion detachably fastened to the intermediate hollow body and adapted to cover the chain ring in such a manner as to permit exposure of the crank pedal therefrom, and a rear shield portion detachably fastened to the intermediate hollow body and adapted to cover the sprocket in such a manner as to permit exposure of the axle therefrom. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] 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:  
     [0010]FIG. 1 is a perspective view of a conventional bicycle;  
     [0011]FIG. 2 is side view of a bicycle according to the present invention;  
     [0012]FIG. 3 is a fragmentary perspective view of the bicycle, in which, a chain casing is partly exploded to illustrate interior of the same;  
     [0013]FIG. 4 is a fragmentary rear view of the bicycle;  
     [0014]FIG. 5 is an exploded perspective view of the chain casing employed in the bicycle of the present invention;  
     [0015]FIG. 6 is a cross sectional view of the chain casing taken along lines VI-VI in FIG. 5;  
     [0016]FIG. 7 is a side view of a modified bicycle according to the present invention;  
     [0017]FIG. 8 is a fragmentary perspective view of the modified bicycle, in which, a chain casing is partly exploded to illustrate interior of the same;  
     [0018]FIG. 9 is an exploded perspective view of another chain casing adapted for use in the modified bicycle of the present invention; and  
     [0019]FIG. 10 is a sectional view of the chain casing shown in FIG. 9. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0020] Referring to FIGS.  2  to  5 , the preferred embodiment of a bicycle  30  of the present invention is shown to include a cross bar  35  having a front end connected to a down tube  32  and a rear end, a seat  39  disposed securely on the rear end of the cross bar  35 , a head tube  34  having an upper end connected to a handle  38 , a front fork  37  extending downwardly from a lower end of the head tube  34  to permit mounting of a front wheel  62  thereon, a crank unit  40  fixed to a lower end of the down tube  32  via a horizontal crank-mounting tube  31  and formed with a chain ring  42 , a crank pedal  41  co-axially connected to the chain ring  42 , an axle  61  disposed rearwardly of the chain ring  42 , a sprocket  43  mounted on the axle  61 , a chain stay  33  extending between the chain ring  42  and the sprocket  43 , and a chain  44  trained on the chain ring  42  and the sprocket  43  and having upper and lower chain sections  441 ,  442 . A shock absorbing unit  36  is disposed between and interconnects the cross bar  35  and the chain stay  33 . A rear wheel  60  is rotatably mounted on the axle  61 , and is operably fastened to the sprocket  43  in such a manner that the sprocket  43  co-rotates with the chain ring  42  when the crank pedal  41  is pedaled in a forward direction.  
     [0021] A chain casing  50  of the present invention includes a front shield portion  51 , a rear shield portion  53 , and an intermediate hollow body  52 . The intermediate hollow body  52  is fixed to the chain stay  33 , and extends between the chain ring  42  and the sprocket  43 . The hollow body  52  has front and rear ends, a peripheral wall extending from the front end to the rear ends and defining a receiving space, and first and second partitions  524 ,  525  extending in the receiving space to divide the receiving space into upper and lower compartments  526 ,  528  that receive the upper and lower chain sections  441 ,  442 , respectively, and an intermediate compartment  527  between the upper and lower compartments  526 ,  528 . A tensioning wheel  70  is disposed between the front end of the intermediate hollow body  52  and the chain ring  42 , and is disposed below and is in sliding contact with the lower chain section  442  of the chain  44 . The lower chain section  442  straddles the tensioning wheel  70  and then turns downward to contact the chain ring  42 .  
     [0022] The front shield portion  51  is detachably fastened to the intermediate hollow body  52  via screws  54 , and covers the chain ring  42  in such a manner as to permit exposure of the crank pedal  41  therefrom. The rear shield portion  53  is detachably fastened to the intermediate hollow body  52 , and is mounted on the axle  61  via a fastener nut  55  so as cover the sprocket  43  in such a manner to permit exposure of the axle  61  therefrom. The intermediate compartment  527  is disposed to receive cables, such as brake cables and gear cables (not shown).  
     [0023] Preferably, first and second sound-absorbing members  81 ,  82  are mounted respectively in the upper and lower compartments  526 ,  528  (see FIG. 6) around the upper chain section  441  and the lower chain section  442  of the chain  44  so as to absorb vibrating sound resulting from rotation of the chain ring  42 .  
     [0024] Referring to FIGS. 7 and 8, a modified preferred embodiment of a bicycle according to the present invention is shown to be similar to the previous embodiment in construction. The main difference resides in that the intermediate hollow body  92  further has a third partition  929  extending in the intermediate compartment  927  and parallel to the first and second partitions  924 ,  925  so as to divide the intermediate compartment  927  into two minor compartments  927 ″. The peripheral wall of the intermediate hollow body  92  includes a side cover  95  which is detachable so as to expose the upper, lower, and intermediate compartments  926 ,  928 ,  927 .  
     [0025] Referring to FIGS. 9 and 10, a modified chain casing is shown to be similar to the previous embodiment in construction. The main difference resides in that the intermediate hollow body  92  includes left and right side plates  921 ,  922 , first, second and third partitions  924 ,  925 ,  929  interposed between the left and right side plates  921 ,  922  to define the upper, lower and intermediate compartments  926 ,  928 ,  927 , and upper and lower plates  94 ,  96  detachably mounted to upper and lower ends of the left and right side plates  921 ,  922  so as to cover the upper and lower compartments  926 ,  928 .  
     [0026] 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 this invention be limited only as indicated in the appended claims.