Abstract:
A shaft coupling assembly comprising a coupling element including a shaft-receiving slot configured to receive a shaft. A retaining bolt is extendable through the coupling element adjacent the shaft receiving slot and to be received and retained in a bolt receiving recess in the upper shaft surface adjacent the forward shaft end after the shaft forward end is inserted in the coupling element slot. At least one projection extends from the shaft forward end adjacent the shaft upper surface to prevent improper clamping of the shaft forward end and any associated feeling of proper interconnection.

Description:
BACKGROUND  
         [0001]    The present invention relates to shaft components. More particularly, the present invention relates to a safety mechanism for reducing the likelihood of an improper shaft assembly.  
           [0002]    Shafts are utilized in many applications and generally require interconnection between the shaft and a secondary component. The secondary component can be an independent component or secondary shafts such that the shaft serves as an intermediate shaft. In both instances, the forward end  22  of the shaft  20  is interconnected with a coupling element  10  which in turn is interconnected with the secondary component (not shown).  
           [0003]    Many different coupling elements can be utilized with the present invention, with an exemplary coupling element  10  illustrated in FIG. 1. The coupling element  10  has a shaft receiving and retaining slot  12  and a retaining bolt  16  that is passed through and secured in a through bore  14  in the coupling element  10 . Typically, the shaft  20  has a notch, annular groove or other form of bolt receiving recess  24  adjacent the forward end  22  of the shaft  20 . The forward end  22  of the shaft  20  is first positioned in the slot  12  (as indicated by the arrow  1  in FIG. 1) with the bolt receiving recess  24  aligned with the through bore  14 . Thereafter, the retaining bolt  16  is slid through the through bore  14  and bolt receiving recess  24  (as indicated by the arrow  2  in FIG. 1) and secured by a cotter pin, nut or the like. The retaining bolt  16  extending through the bolt receiving recess  24  permanently secures the shaft  20  to the coupling element  10 .  
           [0004]    In many applications, for example, a steering intermediate shaft, the interconnection of the shaft  20  and coupling element  10  occurs in a location with limited accessibility. As such, it is difficult to visually or manually check that the retaining bolt  16  is properly received in the bolt receiving recess  24 . For example, as illustrated in FIG. 2, the shaft  20  may not be fully inserted into the coupling element slot  12  when the retaining bolt  16  is inserted. As a result, the retaining bolt  16  is not received in the bolt receiving recess  24 . In some instances, the forward end  22  of the shaft  20  jams between the inserted retaining bolt  16  and the inner surface  18  of the coupling element slot  12 . If the shaft  20  is jammed sufficiently, it may give a rigid feeling to an assembly worker, thereby creating a false sense that the shaft  20  is properly interconnected. After some use, the shaft end  22  may dislodge from between the retaining bolt  16  and slot surface  18 , thereby causing disassembly and failure of the coupling.  
         SUMMARY  
         [0005]    The present invention provides a shaft coupling assembly. The assembly comprises a coupling element including a shaft-receiving slot configured to receive a shaft. A retaining bolt is extendable through the coupling element adjacent the shaft receiving slot. The shaft includes an axial shaft body having upper and lower surfaces and terminating in a forward end configured to be inserted into the coupling element slot. A bolt receiving recess in the upper shaft surface adjacent the forward shaft end is configured to receive and retain the retaining bolt after the shaft forward end is inserted into the coupling element slot. At least one projection extends from the shaft forward end adjacent the shaft upper surface whereby, in the event the retaining bolt is extended through the coupling element prior to proper insertion of the shaft forward end into the coupling element slot, the projection contacts the retaining bolt and prevents improper clamping of the shaft forward end and any associated feeling of proper interconnection. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is an isometric view of a prior art shaft positioned for engagement with an exemplary coupling element.  
         [0007]    [0007]FIG. 2 is a side elevation view, with the coupling element shown in cross section, of a prior art shaft improperly interconnected with the coupling element.  
         [0008]    [0008]FIG. 3 is a side elevation view of a shaft of a first embodiment of the present invention positioned for engagement with an exemplary coupling element.  
         [0009]    [0009]FIG. 4 is a top elevation view of the shaft of FIG. 3 positioned for engagement with an exemplary coupling element.  
         [0010]    FIGS.  5 - 7  are side elevation views, with the coupling element shown in cross section, of the shaft of FIG. 3 improperly inserted into the coupling element.  
         [0011]    [0011]FIG. 8 is a side elevation view of a shaft of a second embodiment of the present invention positioned for engagement with an exemplary coupling element.  
         [0012]    [0012]FIG. 9 is a top elevation view of the shaft of FIG. 8 positioned for engagement with an exemplary coupling element.  
         [0013]    [0013]FIG. 10 is a side elevation view, with the coupling element shown in cross section, of the shaft of FIG. 8 initially improperly inserted into the coupling element.  
         [0014]    [0014]FIG. 11 is a side elevation view similar to FIG. 10, illustrating the improperly inserted shaft automatically withdrawing from the coupling element.  
         [0015]    FIGS.  12 - 13  are side elevation views, with the coupling element shown in cross section, of the shaft of FIG. 8 improperly inserted into the coupling element. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    The present invention will be described with reference to the accompanying drawing figures wherein like numbers represent like elements throughout. Certain terminology, for example, “right”, “left”, “front”, “frontward”, “forward”, “back”, “rear” and “rearward”, is used in the following description for relative descriptive clarity only and is not intended to be limiting.  
         [0017]    Referring to FIGS.  3 - 5 , a shaft  30  of the first embodiment of the present invention is shown. The shaft  30  has an axial body extending between a forward end  32  and a rear end (not shown). The shaft  30  includes a bolt receiving recess  34  adjacent the forward end  32  of the shaft  30 . The bolt receiving recess  34  is similar to the bolt receiving recess  24  of the prior art shaft  20  and is configured and positioned to receive the retaining bolt  16 . The shaft  30  generally terminates in a blunt end  36  forward the bolt receiving recess  34 . The shaft  30  has a generally complete cross-sectional area at the bolt receiving recess  34  such that a secure engagement occurs between the retaining bolt  16  and bolt receiving recess  34 . A projection  40  extends from the generally blunt end  36  adjacent the top surface of the shaft  30 . The projection  40  preferably terminates in a tapered tip  42 .  
         [0018]    Referring to FIGS.  5 - 7 , the projection  40  extending from the shaft  30  prevents a false sense of proper interconnection between the shaft  30  and the coupling element  10  that may be experienced with the prior art shaft  20 . As illustrated in FIG. 5, if the retaining bolt  16  is inserted prior to insertion and proper positioning of the shaft  30 , the tapered tip  42  of the projection  40  first contacts the retaining bolt  16 , thereby causing the shaft  30  to tilt out of the proper axial alignment. Tilting of the shaft  30  provides an assembly worker with a visual indication that something, most likely an improperly inserted retaining bolt  16 , is preventing proper insertion of the shaft  30  into the coupling element  10 . Referring to FIGS. 6 and 7, if the shaft  30  is only partially inserted, the projection tip  40  will help prevent a false sense of proper interconnection. As shown in FIG. 6, the projection  40  may block the through bore  14 , thereby preventing insertion of the bolt  16  until the shaft  30  is properly inserted. Referring to FIG. 7, the projection  40  is preferably a length at least equal to the distance from the through bore  14  to the entry of the slot  12 . As such, the full cross-sectional area of the shaft  30  is not received into the slot  12  until at least a portion of the projection  40  is blocking the through bore  14 . Due to the reduce cross-sectional area, it is not possible for the coupling element  10  to clamp onto the forward end of the shaft  30 .  
         [0019]    Referring to FIGS.  8 - 13 , a shaft  50  of the second embodiment of the present invention is shown. The shaft  50  has an axial body extending between a forward end  52  and a rear end (not shown). The shaft  50  includes a bolt receiving recess  54  adjacent the forward end  52  of the shaft  50 . The bolt receiving recess  54  is similar to the bolt receiving recess  24  of the prior art shaft  20  and is configured and positioned to receive the retaining bolt  16 . The shaft  50  generally terminates at end surface  56  forward the bolt receiving recess  54 . Again, the shaft  50  has a generally full area at the bolt receiving recess  54  such that a secure engagement occurs between the retaining bolt  16  and bolt receiving recess  54 . A top projection  60  extends from the end surface  56  adjacent the top surface of the shaft  50  and a bottom projection  70  extends from the end surface  56  adjacent the bottom surface of the shaft  50  with an open space  80  defined therebetween. Each projection  60 ,  70  terminates in a tapered tip  62 ,  72 , respectively. Referring to FIGS. 8 and 9, each projection  60 ,  70  preferably narrows moving forward from the end surface  56  in both the vertical direction (FIG. 6) and the horizontal direction (FIG. 7). As such, each projection  60 ,  70  has a slight flexibility.  
         [0020]    Referring to FIGS.  10 - 13 , the projections  60  and  70  extending from the shaft  50  prevent the false sense of proper interconnection between the shaft  50  and the coupling element  10  and further automatically withdraw a shaft  50  that is improperly inserted after insertion of the retaining bolt  16 . As illustrated in FIGS. 10 and 11, if the retaining bolt  16  is inserted prior to insertion and proper positioning of the shaft  50 , the tapered tip  62  of the projection  60  first contacts the retaining bolt  16 , thereby causing the projections  60  and  70  to compress between the retaining bolt  16  and the slot inner surface  18  with projection  60  flexing inward toward the open area  80  as indicated by arrow A in FIG. 10. Compression of the projections and thereby flexing of projection  60  creates an axial spring force in the direction of arrow B in FIG. 11. The created spring force causes the improperly assembled shaft to “pop” from the coupling element slot. The withdrawing shaft  50  again provides an assembly worker with a visual indication that something, most likely an improperly inserted retaining bolt  16 , is preventing proper insertion of the shaft  50  into the coupling element  10  and prevents any false sense of proper interconnection.  
         [0021]    Referring to FIGS. 12 and 13, if the shaft  50  is only partially inserted, the projection tips  60  and  70  will help prevent a false sense of proper interconnection. As shown in FIG. 12, the top projection  60  may block the through bore  14 , thereby preventing insertion of the bolt  16  until the shaft  50  is properly inserted. Referring to FIG. 13, the open space  80  between the projections  60  and  70  extends a length at least equal to the distance from the through bore  14  to the entry of the slot  12 . As such, the full cross-sectional area of the shaft  50  is not received into the slot  12  until at least a portion of the top projection  60  is blocking the through bore  14 . Due to the reduce cross-sectional area, it is not possible for the coupling element  10  to clamp onto the forward end of the shaft  50 .  
         [0022]    It will be appreciated by those skilled in the art that changes can be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed.