Abstract:
A method of preventing rotation of an axle of a bicycle including a dropout having a recess. The method includes coupling a motor to the axle, attaching a torque element to an end of the axle, engaging the torque element into the recess in the dropout, and inhibiting rotation of the axle relative to the dropout in response to torque from the motor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of and claims priority to U.S. patent application Ser. No. 13/422,810, filed Mar. 16, 2012, now U.S. Pat. No. 9,010,792, the entire contents of each of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates generally to bicycles, and more specifically to motor-driven electric bicycles. 
         [0003]    Bicycles commonly have a main frame and a front fork pivotally secured to the main frame. The main frame typically includes a top tube, a down tube, a seat tube, and a rear wheel mount for receiving a rear wheel axle. The front fork typically includes a front wheel mount for receiving a front wheel axle. Steering control of the bicycle is provided by a handlebar that is usually secured to the front fork via a handlebar stem. 
         [0004]    Some bicycles also include a hub motor that is mounted to the rear axle to assist with propelling the bicycle. In existing motor-driven electric bicycles, torque from the motor is transferred to the frame. Often, the torque exceeds the clamping forces on the rear axle, which causes the axle to spin freely relative to the frame. In some instances, a torque arm is externally bolted to the frame using a special connector and is further coupled to the axle to prevent axle rotation. Existing torque arms are prone to failure, and when they do fail, wires connected to the motor can become tangled and/or destroyed, potentially injuring the rider. 
       SUMMARY 
       [0005]    The present invention provides a bicycle including a wheel that has an axle with a first end and a second end, a motor coupled to the axle, and a frame supported by the wheel. The frame includes a first dropout and a second dropout. The first dropout defines a recess, and the bicycle includes a torque element that is secured to the first end of the axle and that is shaped to fit within the recess of the first dropout to inhibit rotation of the axle relative to the frame in response to torque from the motor. 
         [0006]    In one construction, the present invention provides a bicycle including a wheel that has an axle with a non-cylindrical first end and a second end, and a motor coupled to the axle. The bicycle also includes a frame that is supported by the wheel and that has a dropout with the first wall that defines a recess, and a torque element that is non-rotationally coupled to the first end of the axle. The torque element includes a second wall that is engageable with the first wall to inhibit rotation of the axle in response to torque from the motor. 
         [0007]    In another construction, the present invention provides a method of preventing rotation of an axle the bicycle that has a dropout with a recess. The method includes coupling a motor to the axle, attaching a torque element to an end of the axle, engaging the torque element with the dropout within the recess, and inhibiting rotation of the axle in response to torque from the motor. 
         [0008]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a side view of a bicycle including a frame embodying the present invention. 
           [0010]      FIG. 2  is a perspective view of a rear axle area of the bicycle illustrated in  FIG. 1 , including left and right dropouts, an axle, a motor, and a torque element positioned between the left dropout and the axle. 
           [0011]      FIG. 3  is a perspective view of a portion of the rear axle and the right dropout. 
           [0012]      FIG. 4  is an exploded view of a portion of the rear axle area illustrated in  FIG. 2 , including the dropouts, the axle, and the torque element. 
           [0013]      FIG. 5  is an exploded perspective view of the left dropout, the axle, and the torque element. 
           [0014]      FIG. 6  is an exploded perspective view of the right dropout, the axle, and a rear derailleur hanger. 
           [0015]      FIG. 7  is a perspective view of the axle and the torque element prior to assembly. 
           [0016]      FIG. 8  is a perspective view of the torque element attached to the axle. 
           [0017]      FIG. 9  is a perspective view of the interior side of the torque element nested in the left dropout. 
       
    
    
       [0018]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
       DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a bicycle  10  that includes a front wheel  15 , a rear wheel  20 , and a frame  25 . The frame  25  has a head tube  30  and a front fork  35  rotationally supported by the head tube  30  and that secures the front wheel  15  to the frame  25 . A handlebar assembly  40  is coupled to the head tube  30  and is secured to the front fork  35  by a stem assembly  45 . The frame  25  also has a top tube  50  connected to and extending rearward from the head tube  30 , and a down tube  55  connected to the head tube  30  below the top tube  50  and extending generally downward toward a drive train  60 . A seat tube  65  is connected to the top tube  50  and the down tube  55 , and a seat  70  is supported by the seat tube  65 . 
         [0020]    With reference to  FIGS. 1 and 2 , the frame  25  also includes a rear triangle that is connected to the rear wheel  20 . The rear triangle includes opposed seatstays  75  (one shown), a left chainstay  80 , and a right chainstay  85 . A left dropout  90  is disposed at a lower end of the one seatstay  75  and is connected to the left chainstay  80 . A right dropout  95  is disposed at the lower end of the right seatstay  75  and is connected to the right chainstay  85 .  FIGS. 2 and 4  show that a rear axle system  100  of the rear wheel  20  includes an axle  105  extending between the dropouts and an axle rod  110  that secures the rear wheel  20  in the dropouts  90 ,  95  to rotatably attach the rear wheel  20  to the frame  25 . Although not shown, a bearing set (not shown) couples a hub (not shown) to the axle  105  such that the rear wheel  20  can freely rotate about the axle  105 . 
         [0021]      FIGS. 4 and 5  show that the left dropout  90  has a recess  115  accessible from adjacent a lower edge or bottom of the dropout  90  and from the interior or wheel side of the frame  25 . The recess  115  is defined by converging side walls  120  (interior walls) and a planar bottom surface  125 . Each of the illustrated converging side walls  120  has a planar section and is joined to the other wall  120  at an apex of the recess  115 . A hole  130  extends through the left dropout  90  near the apex of the converging walls  120 , and the axle  105  is aligned with the hole  130 . 
         [0022]    Referring to  FIGS. 2-4  and  6 , a rear derailleur hanger  135  is connected to the right dropout  95  using a fastener  137  (see  FIG. 4 ) that is threaded into a hole  138 . As illustrated in  FIGS. 3 and 6 , the hanger  135  is keyed into a recessed area  140  of the right dropout  95  and has a recess  145  on one side of the hanger body. The recess  145  is shaped to receive the axle  105  and is accessible from adjacent a lower edge or bottom of the right dropout  95  and from an interior or wheel side of the frame  25 . In particular, the recess  145  of the right dropout  95  is defined by converging side walls  150  and a planar bottom surface  155  similar to the recess  115  of the left dropout  90 . Also like the recess  115 , each of the illustrated converging side walls  150  has a planar section and is joined to the other wall  150  at an apex of the recess  145 . A hole  160  ( FIG. 6 ) of the hanger  135  near the apex of the converging walls  150  aligns with a threaded hole  162  extending through the right dropout  95  near the apex of the converging walls  150  to receive the axle rod  110 , as explained in detail below. 
         [0023]    In other constructions, the rear derailleur hanger  135  may be formed as a single piece with the right dropout  95 , the hanger  135  may be connected in a different way (e.g., welding, brazing, adhesive), or the hanger  135  may be attached to a different component (e.g., the rear right chainstay  85 , the right seatstay  75 ) Additionally, the left chainstay  80  and the left seatstay  75  may be formed as a single piece or be coupled together differently. Likewise, the right chainstay  85  and the right seatstay  75  may be formed as a single piece or be coupled together differently, as desired. 
         [0024]    As illustrated, the recesses  115 ,  145  of both dropouts  90 ,  95  are generally wedge-shaped (see  FIGS. 5 and 6 ) when viewed from the interior side of the frame  25 , although either or both recesses  115 ,  145  can have different shapes. The wide mouth or opening defined by each recess  115 ,  145  near the lower edge of the respective dropouts  90 ,  95  provides a relatively large access opening for receiving the axle  105  so that the rear wheel  20  can be easily attached to the frame  25  within the dropouts  115 ,  145 . Although the recess  145  of the right dropout  95  is illustrated as being shallower than the recess  115  of the left dropout  90 , the recess  145  can have the same or different depth relative to the recess  115 . 
         [0025]    With reference back to  FIG. 1 , the drive train  60  includes a crankset  165  that is rotatably mounted to a bottom bracket (not shown). A front derailleur  170  shifts a chain  175  between different chain rings  180  (one shown), and is actuated by the handlebar assembly  40 . A plurality of rear cogs  185  are mounted to the rear wheel  20  and connected to the crankset  165  by the chain  175 . A rear derailleur  190  is attached to the derailleur hanger  135  and shifts the chain  175  between the different rear cogs  185  and is actuated by the handlebar assembly  40 . 
         [0026]      FIGS. 2-4  show that the axle  105  includes a first end  195  disposed in the left dropout  90 , and a second end  200  engaged with the rear derailleur hanger  135  and disposed in the right dropout  95 . With reference to  FIGS. 4 and 5 , the first end  195  has a keyed or hexagonal shape, although the first end  195  can have any suitable non-cylindrical shape or polygonal shape. Stated another way, the first end  195  is non-circular in cross-section. As illustrated in  FIGS. 4 and 6 , the second end  200  is substantially cylindrical and has a stepped taper  205 . A central portion  210  of the axle  105  extends between the first and second ends  195 ,  200  to support bearings (not shown). 
         [0027]    With reference to  FIGS. 4 ,  7 , and  8 , a passageway  215  extends through the axle  105  from the first end  195  to the second end  200  to receive the axle rod  110  when the rear axle system  100  is assembled onto the bicycle  10 .  FIG. 4  shows that the axle rod  110  has a head  220  engageable by a tool (e.g., Allen wrench or another wrench, screw driver, etc.) and a threaded distal end  225 . As illustrated, the axle  105  is aligned with the holes  160 ,  162  so that the axle rod  110  can extend through the left dropout  90 , the axle  105 , and the hanger  135 , and threadably engage the right dropout  95  within the hole  162  to secure the rear wheel  20  to the frame  25 . In some cases, the right dropout  95  can include a threaded insert (not shown) to attach the axle rod  110  to the right dropout  95 . When assembled, the head  220  of the axle rod  110  abuts the left dropout  90 . The illustrated axle rod  110  is only exemplary, and can be replaced by other suitable components (e.g., a quick connect skewer, etc.) to suit the desired connection between the rear wheel  20  and the frame  25 . 
         [0028]    Referring to  FIGS. 2 ,  4 ,  5 , and  7 - 9 , a torque element  230  is attached to the first end  195  of the axle  105  and is shaped to fit within the recess  115  of the left dropout  90 . FIGS.  5  and  7 - 9  show that the torque element  230  is wedge-shaped and is nested in the recess  115  such that the torque element  230  is substantially hidden from view when the bicycle  10  is viewed from adjacent the exterior sides of the frame  25 . That is, the torque element  230  is shielded by the left dropout  90  on its upper and outer surfaces. As shown in  FIGS. 2 and 4 , the torque element  230  is housed in the dropout  90  when the rear wheel  20  is coupled to the frame  25  such that the torque element  230  is form fit into the dropout  90 . As illustrated, an exterior wall or surface  235  of the torque element  230  is shaped to conform to the converging side walls  120  when the torque element  230  is disposed in the recess  115 . 
         [0029]      FIGS. 5 ,  7 , and  8  show that the torque element  230  has a non-cylindrical aperture  240  (non-circular in cross-section) that is shaped to fit onto the first end  195  of the axle  105 . In particular, the illustrated torque element  230  has a hexagonally-shaped aperture  240  that mates to the hexagonally-shaped first end  195  of the axle  105 . A fastener  245  extends through a threaded hole  250  in the torque element  230  to secure the torque element  230  to the axle  105  so that when the rear wheel  20  is removed from the frame  25 , the torque element  230  remains attached to the axle  105 . In some constructions, the first end  195  and the torque element  230  can have other mating structures. For example, the first end  195  of the axle  105  can have other polygonal shapes (e.g., triangular, square, trapezoidal, pentagonal, etc.) and the aperture  240  can have a complementary polygonal shape. In other constructions, the first end  195  and the aperture  240  can have any complementary non-circular cross-sectional shapes (e.g., obround, oblong, etc.). In some cases, the torque element  230  can be press fit onto the axle  105 . 
         [0030]    As shown in  FIG. 2 , the bicycle  10  also includes a motor  255  that is drivingly coupled between the drive train  60  and the axle  105  to selectively provide motive force for the bicycle  10  via the rear wheel  20 . Specifically, a stator portion of the motor is secured to the axle  105  and a rotor portion (not shown) of the motor  255  is coupled to the drive train  60 . The motor  255  is electrically connected to a power source or battery pack  260  (e.g., stored in the down tube  55 ) by a power cable (not shown), and a controller can be used to control the motor  255  and other electrical accessories on the bicycle  10 . As illustrated in  FIGS. 4 ,  5 , and  7 - 9  the torque element  230  has an extension  265  (near the bottom of the torque element  230 , as viewed in  FIG. 2 ) that defines a pocket  270  to hold the power cable away from other components of the rear wheel  20  (e.g., disc rotor bolts, not shown). With reference to  FIGS. 7 and 8 , the surfaces of the pocket  270  are angled generally upward from adjacent the exterior side of the torque element  230  toward the interior side of the torque element so that the power cable does not interfere with rotation of the rear wheel  20 . 
         [0031]    The torque element  230  is non-rotatably attached to the axle  105  and cooperates with the dropout  90  to resist torque from the motor  255  and thus prevent axle rotation in response to motor torque. To attach the wheel  20  with the motor  255  to the frame  25 , the second end  200  of the rear axle  105  is aligned with the recess  145  in the right dropout  95 , and the torque element  230  is aligned with the recess  115  in the left dropout  90 . The torque element  230  slides generally vertically upward into the recess  115  of the left dropout  90  from the underside of the frame  25 , and the second end  200  of the axle  105  is positioned in the recess  145  of the right dropout  95  and snugly aligned with the hole  160 . The torque element  230  is accurately positioned in the left dropout  90  due to the complementary shapes of the recess  115  and the torque element  230 . The axle rod  110  is then inserted through the left dropout  90 , the axle  105 , the hanger  135 , and threaded into the right dropout  95  by engaging the appropriate tool with the head  220 . Because the recess  115  is located on the interior side of the dropout  90 , the torque element  230  is substantially hidden from view. 
         [0032]    When the motor  255  is actuated, a significant amount of torque is applied to the wheel, and the axle  105  has a tendency to counter-rotate in response to motor torque. As described, the torque element  230  is fixed to the first end  195  of the axle  105  and snugly fits in the dropout  90  within the recess  115 . The torque element  230  is essentially an internal component of the rear axle system  100  that is form fit into the dropout  90  and around the axle  105  to prevent axle rotation in response to motor torque. Due to the complementary oblong or wedge-shaped recess  115  and the torque element  230 , the torque element  230  cannot move relative to the dropout  90 . Further, because the torque element  230  is also rigidly attached to the axle  105 , any tendency for the axle  105  to rotate in response to motor torque is prevented by the torque element  230 . Stated another way, any tendency for axle rotation due to motor torque (or other factors) is inhibited due to the non-rotational attachment of the torque element  230  to the axle  105  and to the tight-fitting arrangement between the recess  115  and the torque element  230 . 
         [0033]    Various features and advantages of the invention are set forth in the following claims.