Abstract:
A motorcycle includes a frame and a flexible drive member. The frame is provided with an aperture. An engine is attached to the frame and is configured to selectively rotate a drive sprocket. A driven sprocket is attached to a rear wheel. A flexible drive member operably couples the drive sprocket and the driven sprocket and, in doing so, passes through the aperture in the frame. Methods of manufacturing a motorcycle are also provided.

Description:
TECHNICAL FIELD 
     A motorcycle includes a frame and a flexible drive member. The flexible drive member operably couples a drive sprocket and a driven sprocket and passes through an aperture in the frame. 
     BACKGROUND 
     Conventional motorcycles often include a flexible drive member which operably couples a driven sprocket on a rear wheel with, a drive sprocket associated with an engine. The flexible drive member commonly comprises a chain or a belt. In routing die flexible drive member to avoid undesired contact with other components of the motorcycle, disposition of the flexible drive member can contribute to an increased overall width of the motorcycle. In addition, guards might be provided to prevent inadvertent contact of the flexible drive member with the leg or other body part of an operator. Such guards can additively contribute to an increased overall width of the motorcycle, and can additionally be heavy, bulky, prone to rattling, difficult to install, difficult to clean, and aesthetically unattractive. 
     SUMMARY 
     In accordance with one embodiment, a motorcycle comprises a frame, a drive sprocket, an engine, a swingarm, a rear wheel, a driven sprocket, and a flexible drive member. The frame extends from a forward end to a rearward end. The frame is provided with a first aperture adjacent to the rearward end. The engine is attached to the frame and is configured to selectively rotate the drive sprocket. The swingarm is pivotally attached to the frame adjacent to the rearward end of the frame. The rear wheel is rotatably attached to the swingarm. The driven sprocket is attached to the rear wheel. The flexible drive member operably couples the drive sprocket and the driven sprocket. The flexible drive member passes through the first aperture in the frame. 
     In accordance with another embodiment, a motorcycle comprises a frame, a drive sprocket, an engine, a swingarm, and a flexible drive member. The frame extends from a forward end to a rearward end and comprises a left main frame member and a right main frame member. The left main frame member and the right main frame member each extend obliquely downwardly and rearwardly from the forward end to the rearward end. The forward end of the frame comprises a steering interface and the rearward end of the frame comprises a swingarm interface. One of the left main frame member and the right main frame member is provided with a first aperture adjacent to the rearward end. The engine is attached to the frame at a location at least partially between the left main frame member and the right main frame member. The engine is configured to selectively rotate the drive sprocket. The swingarm is attached to the swingarm interface and supports a rear wheel. A driven sprocket is attached to the rear wheel. The flexible drive member operably couples the drive sprocket and the driven sprocket. The flexible drive member passes through the first aperture. 
     In accordance with yet another embodiment, a method of manufacturing a motorcycle is provided. The method comprises providing a frame extending from a forward end to a rearward end. A first aperture is formed in the frame adjacent to the rearward end. An engine is attached to the frame. The engine is configured to selectively rotate a drive sprocket. A swingarm is pivotally attached to the frame adjacent to the rearward end of the frame. A rear wheel is rotatably attached to the swingarm. A drive sprocket is attached to the rear wheel. A flexible drive member is routed over the drive sprocket, through the first aperture in the frame, and over the driven sprocket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the same will be better understood from the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a left side elevational view depicting a motorcycle in accordance with one embodiment; 
         FIG. 2  is a right side elevational view depicting the motorcycle of  FIG. 1 ; 
         FIG. 3  is an enlarged left side elevational view depicting a portion of the motorcycle of  FIG. 1 ; 
         FIG. 4  is a left rear perspective view depicting a portion of the motorcycle of  FIG. 1 , wherein a portion of the chain is shown in dashed lines for clarity of illustration; and 
         FIG. 5  is a rear perspective view depicting a portion of the motorcycle of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are hereinafter described in detail in connection with the views of  FIGS. 1-5 , wherein like numbers indicate the same or corresponding elements throughout the views. In accordance with one embodiment, a motorcycle can be provided with a frame having an aperture configured for passage of a flexible drive member. For example, as shown in the example of  FIGS. 1-5 , a motorcycle  10  is shown to comprise a frame  12  which extends from a forward end  14  to a rearward end  16 . As shown in  FIGS. 1 ,  2  and  4 , the frame  12  can include a left main frame member  18  and a right main frame member  20 . The left main frame member  18  and the right main frame member  20  can each extend obliquely downwardly and rearwardly from the forward end  14  of the frame  12  to the rearward end  16  of the frame  12 . The forward end  14  of the frame  12  can comprise a steering interface  22  and the rearward end  16  of the frame  12  can comprise a swingarm interface  24 . 
     The left and right main frame members  18  and  20  can be spaced from one another along at least part of their extension. However, the left and right main frame members  18  and  20  can connect with and/or contact one another at one or more locations, such as near the forward end  14  at the steering interface  22  and/or near the rearward end  16  at the swingarm interface  24 . In one particular embodiment, as also shown in  FIGS. 1-5 , the left and right main frame members  18  and  20  can be spaced from each other in a generally corresponding and mirroring relationship with respect to, and on opposite sides of, an imaginary vertical plane which bisects the motorcycle  10  along a longitudinal axis of the motorcycle  10  into left and right sides. However, it will be appreciated that a motorcycle in accordance with an alternative embodiment might include any of a variety of alternative frame configurations. 
     The motorcycle  10  is also shown to include a front fork  56 . The front fork  56  is shown to be pivotally attached to the steering interface  22  such that an operator may facilitate steering of the motorcycle  10  through use of a handlebar  58  attached to the front fork  56 . A front wheel  60  can be supported with respect to the frame  12  adjacent to the forward end  14  of the frame  12  such as by rotatably attaching the front wheel  60  to the front fork  56 . The motorcycle  10  is also shown to include a swingarm  32  which is pivotally attached to the swingarm interface  24  of the frame  12 . A rear wheel  34  can be supported with respect to the frame  12  adjacent to the rearward end  16  of the frame  12  such as by rotatably attaching the rear wheel  34  to the swingarm  32 , as shown in  FIGS. 1-5 . The swingarm  32  can be configured to support the rear wheel  34 . 
     The motorcycle  10  is also shown to comprise an engine  26  which is attached to the frame  12 . In one embodiment, as shown in  FIGS. 1-5 , the engine  26  may be attached to the frame  12  at a location at least partially between the left main frame member  18  and the right main frame member  20 . In another embodiment, as also shown in  FIG. 1 , the engine  26  may be attached to the frame  12  at a location between the forward end  14  of the frame  12  and the rearward end  16  of the frame  12 . The left and right main frame members  18  and  20  can be attached to left and right sides of the engine  26  such that the engine  26  hangs downwardly from the frame  12 . As also shown in the embodiment of  FIGS. 1-5 , the motorcycle  10  can be configured such that no portion of the frame  12  extends beneath the engine  26  such as to cradle or protect the engine  26 . However, in this configuration, a muffler  28  can be attached to the engine  26  at a location beneath the engine  26  for protecting the bottom of the engine  26  from damage such as from road debris. It will be appreciated that an engine might alternatively be attached or otherwise supported with respect to the frame of a motorcycle in any of a variety of alternative configurations. 
     The engine  26  may comprise an internal combustion engine such as a V-type engine, as shown in  FIG. 1 . However, it will be appreciated that a motorcycle in accordance with an alternative embodiment might comprise a different type of internal combustion engine. An internal combustion engine can be configured to consume gasoline, diesel fuel, kerosene, natural gas, propane, alcohol, jet fuel, hydrogen, and/or any of a variety of other fuels. In still another embodiment, a motorcycle might be provided with an electric or hybrid drive system in which the engine comprises an electric motor. 
     The motorcycle  10  can also include a drive sprocket  30  which is operatively coupled with the engine  26 . In one embodiment, this operative coupling can involve direct or indirect attachment of the drive sprocket  30  to a transmission or gearbox (e.g.,  36 ) which is directly or indirectly attached to the crankshaft of the engine  26 . As such, the engine  26  can be configured to selectively rotate the drive sprocket  30 . A driven sprocket  38  can be attached to the rear wheel  34  to rotate correspondingly with the rear wheel  34 , as shown in  FIGS. 1-5 . In one embodiment, the driven sprocket  38  can be bolted to the hub of the rear wheel  34 . However, it will be appreciated that the driven sprocket  38  may be attached or supported with respect to the rear wheel  34  in any of a variety of alternative configurations. 
     The motorcycle  10  further comprises a flexible drive member which is configured to operably couple the drive sprocket  30  and the driven sprocket  38 . In one embodiment, as shown in  FIGS. 1-5 , the flexible drive member comprises a chain  40 . In such circumstance wherein the flexible drive member comprises a chain  40 , it will be appreciated that each of the drive sprocket  30  and the driven sprocket  38  can comprise teeth for drivingly engaging the chain  40 . However, in an alternative embodiment, the flexible drive member might comprise a belt such as, for example, a v-type belt or a cogged belt. In such circumstance wherein the flexible drive member comprises a belt, it will be appreciated that the drive sprocket and the driven sprocket can comprise respective pulleys which are configured to drivingly engage the belt. 
     In one embodiment, the frame of a motorcycle comprises at least one aperture which is configured to pass the flexible drive member as it travels between the drive sprocket and the driven sprocket. In one embodiment, the aperture(s) can be provided in the frame adjacent to a rearward end of the frame. For example, in the embodiment of  FIGS. 1-5 , the left main frame member  18  is shown to be provided with first and second apertures  42  and  44  which are each positioned adjacent to the rearward end  16  of the frame  12 . In one embodiment, as shown in  FIG. 4 , the second aperture  44  is spaced from, and thus separated from, the first aperture  42 . The chain  40  is shown in  FIG. 4  to pass through the first aperture  42  in a first direction D 1 , while the chain  40  is shown to pass through the second aperture  44  in a second direction D 2 , such as may be encountered when the motorcycle  10  moves along the ground in a forward direction. The first direction D 1  is shown in  FIG. 4  as being substantially opposite from the second direction D 2 . It will be appreciated that, when the motorcycle  10  moves along the ground in a reverse direction, the directions in which the chain  40  travels through the first and second apertures  42  and  44  can be reversed as compared to those shown in  FIG. 4 . 
     While the embodiment of  FIG. 4  depicts the chain  40  passing through two respective apertures (i.e.,  42 ,  44 ) in the frame  12 , it will be appreciated that an alternative embodiment might involve a flexible drive member passing through only a single aperture in the frame of a motorcycle. In passing through this single aperture, the flexible drive member might pass only once (i.e., in one direction), or can alternatively pass twice (e.g., in substantially opposite directions). It will be appreciated that a motorcycle frame can include one or more apertures which are configured to pass a flexible drive member in any of a variety of alternative configurations in accordance with other embodiments. 
     Referring again to  FIG. 4 , each of the first and second apertures  42  and  44  are shown to define respective passages  43  and  45  for passing the chain  40 . In particular, the left main frame member  18  is shown to comprise an outer wall  62  and an inner wall  64 , both of which are shown to partially define each of the first and second apertures  42  and  44 . The outer wall  62  can be positioned to prevent contact by an operator&#39;s left foot and/or leg with the portion of the chain  40  passing through the first and second apertures  42  and  44 . Likewise, the inner wall  64  can be positioned to prevent that portion of the chain  40  from inadvertently contacting the operator and/or other components of the motorcycle  10 . In this manner, the frame  12  can be configured to provide a guard for the chain  40 . In particular, by passing the chain  40  through an interior passageway (e.g., passages  43  and  45 ) of the frame  12 , the frame  12  can protect the operator of the motorcycle  10  from contacting this portion of the chain  40 , and can thereby serve as a chain guard. While a chain guard type passage might additionally be provided in the swingarm  32 , it will be appreciated that, by providing a chain guard type passage (e.g.,  43  and  45 ) in the frame  12 , as shown in  FIGS. 1-5 , the point of most likely contact of the chain  40  with the foot and/or leg of an operator of the motorcycle  10  can best be covered, and without requiring the provision of bulky bolt-on chain guards or the like which can increase the overall width of the motorcycle  10 . 
     By facilitating passage of the chain  40  through apertures (e.g.,  42  and  44 ) in the frame  12 , it will be appreciated that the motorcycle  10  can accommodate use of a relatively wide tire  35  upon the rear wheel  34 , but while still having a relatively narrow overall body width as shown, for example, in the embodiment of  FIG. 5 . Also, by facilitating passage of the chain  40  through apertures (e.g.,  42  and  44 ) in the frame  12 , it will be appreciated that the width of the frame  12  adjacent to its attachment to the swingarm  32  need not be narrowed to accommodate passage of the chain  40 . Accordingly, by allowing the frame  12  to maintain its full width (which can be slightly greater than the combined width of the tire  35  and the chain  40 , as shown in  FIG. 5 ) at its point of attachment with the swingarm  32 , it will be appreciated that the motorcycle  10  can exhibit increased rigidity as compared with conventional motorcycles. 
     The first and second apertures  42  and  44  are each shown in  FIG. 4  to be elongated to accommodate movement of the chain with respect to the frame  12  resulting from pivotal movement of the swingarm  32  with respect to the frame  12  as would be encountered during suspension travel occurring through use of the motorcycle  10 . For example, as shown in  FIG. 4 , the first aperture  42  is shown to be vertically elongated, meaning that the height of the opening (shown as “H” in  FIG. 4 ) is substantially greater than the height of the chain  40  (shown as “h” in  FIG. 4 ). In this configuration, though the swingarm  32  can move with respect to the frame  12 , thereby causing the relative position of the chain  40  to vary with respect to the frame  12 , the lop and bottom surfaces of the chain  40  generally will not contact the frame  12  adjacent to the first aperture  42  during normal operation of the motorcycle  10 . Likewise, the first aperture  42  is shown to be horizontally elongated, meaning that the width of the opening (shown as “W” in  FIG. 4 ) is substantially greater than the width of the chain  40  (shown as “w” in  FIG. 4 ). In this configuration, despite any side-to-side movement of the chain  40  which may occur during normal operation of the motorcycle  10  (e.g., due to vibration), the side surfaces of the chain  40  generally will not contact the frame  12  adjacent to the first aperture  42 . It will be appreciated that the second aperture  44  can similarly be vertically and horizontally elongated. 
     While the chain  40  is shown in  FIGS. 1-5  as being oriented upon the left side of the motorcycle  10 , it will be appreciated that a motorcycle in accordance with an alternative embodiment can additionally or alternatively include a flexible drive member oriented upon the right side of the motorcycle. It will also be appreciated that a motorcycle having a flexible drive member disposed upon the right side of the motorcycle might include one or more apertures in the frame (e.g., the right main frame member  20 ) which are configured to pass the flexible drive member. 
     The apertures (e.g.,  42  and  44 ) can be formed in the frame through use of any of a variety of suitable techniques. For example, the apertures can be drilled, milled, stamped, cut, or otherwise machined or provided. In still another embodiment, a frame for a motorcycle can be formed in a casting process to include apertures for passing a flexible drive member. When assembling a motorcycle including such a frame, such as the motorcycle  10  of  FIGS. 1-5 , the engine  26  can be attached to the frame  12 . The swingarm  32  can be pivotally attached to the frame  12  adjacent to the rearward end  18  of the frame  12 . The rear wheel  34  can be rotatably attached to the swingarm  32 . The driven sprocket  38  can be attached to the rear wheel  34 . A flexible drive member (e.g., the chain  40 ) can then be routed over the drive sprocket  38 , through the first aperture  42  in the frame  12 , through the second aperture  44  in the frame  12 , and over the driven sprocket  38 . 
     In such circumstance wherein the flexible drive member comprises a chain  40 , as in  FIGS. 1-5 , it will be appreciated that the chain  40  can be selectively breakable such as through use of a master link. Prior to routing the chain  40  through the first and second apertures  42  and  44  in the frame  12 , the master link of the chain can be opened such that one end of the chain  40  can be routed as described above. Once the chain  40  is fully routed, both ends of the chain  40  can be brought together and attached through use of the master link such that the chain  40  comprises a continuous loop. In such circumstance wherein the flexible drive member comprises a belt, it will be appreciated that the belt might be selectively breakable. However, in an alternative embodiment, a non-breakable continuous belt may be employed in accordance with selected embodiments provided that, however, the apertures in the frame include access slots to facilitate installation and removal of the belt as a continuous loop. 
     The foregoing description of embodiments and examples of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the forms described. Numerous modifications are possible in light of the above teachings. Some of those modifications have been discussed and others will be understood by those skilled in the art. The embodiments were chosen and described in order to best illustrate the principles of the invention and various embodiments as are suited to the particular use contemplated. The scope of the invention is, of course, not limited to the examples or embodiments set forth herein, but can be employed in any number of applications and equivalent devices by those of ordinary skill in the art. Rather it is hereby intended the scope of the invention be defined by the claims appended hereto.