Patent Publication Number: US-2015072815-A1

Title: Self-adjusting chain tensioner

Description:
BACKGROUND 
     The embodiments herein relate generally to engine accessories. In particular, embodiments of the present invention relate to engine accessories for motorcycles. 
     A motorcycle has a self-ratcheting tension drive pulley and a bearing pulley that are connected with a chain. The bearing pulley turns around an axel covered with a bearing. The chain runs over a chain tensioner that that is rigid and does not allow chain movement. As the chain heats, from the heat of the engine for instance, it expands. As the chain cools, from the ambient air for instance, it contracts. However, the chain tensioner does not adjust, and as a result force of the bearing changes causing rapid bearing failure from this dynamic loading. Embodiments of the disclosed invention solve this problem. 
     SUMMARY 
     A self-adjusting chain tensioner configured to adjust tension of a chain that connects a self-ratcheting tension drive pulley and a bearing pulley in response to ambient temperature, the self-adjusting chain tensioner comprising: 
     a dynamic block immediately adjacent to the chain; wherein the dynamic block further comprises a right side pair of vertical plate guides and a left side pair of vertical plate guides; 
     a horizontal plate mechanically coupled to the dynamic block with an inner spring and an outer spring permitting the dynamic block to move vertically; 
     a right side vertical plate mechanically coupled to the horizontal plate and immediately adjacent to the right side pair of vertical plate guides; wherein the right side vertical plate assists in movement of the dynamic block in a vertical direction; 
     a left side vertical plate mechanically coupled to the horizontal plate and immediately adjacent to the left side pair of vertical plate guides; wherein the left side vertical plate assists in movement of the dynamic block in the vertical direction; 
     a bracket mechanically coupled to the horizontal plate; wherein the bracket attaches the self-adjusting chain tensioner to a motorcycle; 
     wherein the inner spring and the outer spring can expand or contract in response to changes in the ambient temperature which adjusts a position of the dynamic block and thus keeps consistent tension on the chain which reduces wear on bearings in the bearing pulley 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The detailed description of some embodiments of the invention is made below with reference to the accompanying figures, wherein like numerals represent corresponding parts of the figures. 
         FIG. 1  is a perspective view of an embodiment of the invention shown in use. 
         FIG. 2  is a perspective view of an embodiment of the invention shown in use adapting to chain tension. 
         FIG. 3  is a perspective view of an embodiment of the invention. 
         FIG. 4  is a section detail view of an embodiment of the invention along line  4 - 4  in  FIG. 1 . 
         FIG. 5  is a section detail view of an embodiment of the invention along line  5 - 5  in  FIG. 2 . 
         FIG. 6  is a perspective view of an embodiment of the invention. 
         FIG. 7  is a perspective view of an embodiment of the invention. 
         FIG. 8  is a perspective view of an embodiment of the invention. 
         FIG. 9  is a perspective view of an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS 
     By way of example, and referring to  FIG. 1 ,  FIG. 2  and  FIG. 3 , one embodiment of self-adjusting chain tensioner  10  comprises two vertical plates  12  mechanically coupled to horizontal plate  14 . Horizontal plate  14  is further mechanically coupled to bracket  16 . Bracket  16  can be used to affix horizontal plate  14  to a motorcycle. 
     Turning to  FIG. 4  and  FIG. 5 , dynamic block  20  is immediately adjacent to vertical plates  16  and is mechanically coupled to horizontal plate  14  with inner spring  32  and outer spring  34 . Dynamic block  20  comprises a right side pair of vertical plate guides  22  which accommodate the right side vertical plate  12 . Dynamic block  20  comprises a left side pair of vertical plate guides  22  which accommodate the left side vertical plate  12 . As shown in  FIG. 4  and  FIG. 5 , this permits dynamic block  20  to move in a vertical direction and adjusts the position of dynamic block  20 . 
     Dynamic block  20  can possess many different geometric arrangements, but the following is offered as exemplary. Dynamic block  20  generally takes the shape of an octahedron, modified as follows. A top face is rounded slightly permitting chain C to rest upon the top face and to run over the top face smoothly. The top face is immediately adjacent to a forward face, a back face, a left face and a right face, each of these extend downward and nearly normal to the top face. The front face is immediately adjacent to the left face, the right face and a bottom front face that angles downward and toward the middle of the dynamic block. Likewise, the back face is immediately adjacent to the left face, the right face and a bottom back face that angles downward and toward the middle of the dynamic block. 
     The bottom back face and the bottom front face are both immediately adjacent to a bottom face. The bottom face possesses a cavity which can accommodate inner spring  32  and outer spring  34 . 
     Inner spring  32  can be made in many manners, but the following is exemplary. Inner spring  32  can have a spring constant (k) of 55 lb/in, a 0.075 inch diameter with a right hand wrap. Inner spring  32  can be shock peened steel. 
     Outer spring  34  can be made in many manners, but the following is exemplary. Inner spring  34  can have a spring constant (k) of 125 lb/in, a 0.105 inch diameter with a left hand wrap. Inner spring  32  can be shock peened steel. 
     In this embodiment, inner spring  32  and outer spring  34  are wound in opposite directions. Outer spring  34  has a greater spring constant than inner spring  32 . Both inner spring  32  and outer spring  34  are made of materials that change size in response to heat, which makes them particularly adaptable changes in ambient temperature around chain C. 
     To install self-adjusting chain tensioner  10 , a user simply selects the correct bracket for the preexisting chain tensioner and replaces it with the self-adjusting chain tensioner  10 . There are many designs for bracket  16  as shown in  FIG. 6  though  FIG. 9 . 
       FIG. 6  shows a situation where no bracket is needed. Self-adjusting chain tensioner  110  comprises dynamic block  120 . Dynamic block  120  comprises a right side pair of vertical plate guides  122  which accommodate the right side vertical plate  116  on bracket  114 . Dynamic block  120  comprises a left side pair of vertical plate guides  122  which accommodate the left side vertical plate  116  on bracket  114 . 
       FIG. 7  shows a situation where a longer bracket is needed. Self-adjusting chain tensioner  210  comprises dynamic block  220 . Dynamic block  220  comprises a right side pair of vertical plate guides  222  which accommodate the right side vertical plate  216  on bracket  214 . Dynamic block  220  comprises a left side pair of vertical plate guides  222  which accommodate the left side vertical plate  216  on bracket  214 . 
       FIG. 8  shows a situation where a taller bracket is needed. Self-adjusting chain tensioner  310  comprises dynamic block  320 . Dynamic block  320  comprises a right side pair of vertical plate guides  322  which accommodate the right side vertical plate  316  on bracket  314 . Dynamic block  320  comprises a left side pair of vertical plate guides  322  which accommodate the left side vertical plate  316  on bracket  314 . 
       FIG. 9  shows a situation where a taller bracket with a bolt is needed. Self-adjusting chain tensioner  410  comprises dynamic block  420 . Dynamic block  420  comprises a right side pair of vertical plate guides  422  which accommodate the right side vertical plate  416  on bracket  414 . Dynamic block  420  comprises a left side pair of vertical plate guides  422  which accommodate the left side vertical plate  416  on bracket  414 . Left side vertical plate  416  and right side vertical plate  416  are perforated to accommodate bolt  440 . 
     Persons of ordinary skill in the art may appreciate that numerous design configurations may be possible to enjoy the functional benefits of the inventive systems. Thus, given the wide variety of configurations and arrangements of embodiments of the present invention the scope of the invention is reflected by the breadth of the claims below rather than narrowed by the embodiments described above.