Abstract:
An electric motor driven cycle having a rear wheel, an electric motor configured to deliver power to the rear wheel, and a swing arm coupled between the electric motor and the rear wheel. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

Description:
BACKGROUND  
         [0001]    1. Field  
           [0002]    The present invention relates to power driven cycles, and more specifically, to a swing arm configuration for electric motor driven cycles.  
           [0003]    2. Background  
           [0004]    Conventional electric motor driven cycles generally include a frame suspended between a front and rear wheel. The rear suspension system typically includes a swing arm connecting the rear wheel to the frame and a shock absorber to dampen movement between the swing arm and the frame during operation. A belt drive system can be used to deliver power from an electric motor to the to rear wheel. An idler tensioner is often used to regulate the tension of the drive belt as the swing arm moves in response to sudden bumps in the road. The idler tensioner can be implemented with an adjustable pulley which can move up and down to push the middle of the unloaded part of the drive belt out of a straight line to take up slack. The problem is that the idler tensioner typically has the highest failure rate of any component in the belt drive system. Accordingly, increased reliability can be achieved if the idler tensioner could be eliminated. In addition, the efficiency of the belt drive system can be enhanced by eliminating an extra moving part.  
         SUMMARY  
         [0005]    In one aspect of the present invention, an electric motor driven cycle includes a rear wheel, an electric motor configured to deliver power to the rear wheel, and a swing arm coupled between the electric motor and the rear wheel.  
           [0006]    In another aspect of the present invention, an electric motor driven cycle includes a rear wheel, an electric motor, means for transmitting power from the electric motor to the rear wheel, and a swing arm coupled between the electric motor and the rear wheel.  
           [0007]    In yet another aspect of the present invention, an electric motor driven cycle includes a rear wheel, an electric motor configured to deliver power to the rear wheel, and a swing arm cantilevered from the electric motor and supporting the rear wheel.  
           [0008]    It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only exemplary embodiments of the invention by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    Aspects of the present invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a perspective view of an exemplary electric motor driven cycle;  
         [0011]    [0011]FIG. 2A is a side view illustrating an exemplary mounting configuration for a swing arm;  
         [0012]    [0012]FIG. 2B is a side view illustrating an alternative exemplary mounting configuration for a swing arm;  
         [0013]    [0013]FIG. 3 is a cross-section top view showing an exemplary mounting configuration of a swing arm between an electric motor drive shaft and a rear wheel axle; and  
         [0014]    [0014]FIG. 4 is a side view of an exemplary electric motor driven cyclic with a cosmetic overlay around the frame. 
     
    
     DETAILED DESCRIPTION  
       [0015]    The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments in which the present invention can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are shown generally in order to avoid obscuring the concepts of the present invention.  
         [0016]    [0016]FIG. 1 is a perspective view of an electric motor driven cycle. The electric motor driven cycle  102  is based on a fully suspended and dampened monocoque frame design. A monocoque frame is a type of construction in which the outer surface bears all or a major portion of the stresses. The monocoque frame  104  can be formed as a unitary structure with one or more compartments to house the internal components of the electric motor driven cycle  102 . The internal components include an electric motor  106  powered by dual batteries  108   a  and  108   b,  and a battery charger  110  to periodically charge the batteries  108   a  and  108   b.  Alternatively, the frame can be a conventional tube design such as a diamond or cross frame.  
         [0017]    The frame  104  can be coupled to a front wheel  112  with a front fork assembly  114 . The front fork assembly  114  includes a bifurcated member  116  with right and left spring loaded damping tubes  118   a  and  118   b  extending downward to form a front fork. The axle of the front wheel  112  can be inserted into the front fork. A steered tube  120  extending upward from the center of the bifurcated member  116  can be rotatably inserted through the frame  104  with upper and lower bearings (not shown). Right and left cross-members  122   a  and  122   b  can be secured to the frame  104  to prevent buckling due to compressive loading between the two bearing points. A clamp  124  can be used to couple the steered tube  120  to a handle bar  126 .  
         [0018]    Power can be delivered to a rear wheel  128  with a belt drive assembly between the electric motor  106  and the rear wheel  128 . A drive belt  135  can be connected between a toothed pulley  136  at the end of the motor drive shaft and a toothed drive wheel  138  extending from the rear wheel axle. The toothed configuration of both the pulley and drive wheel tends to reduce slippage during rapid accelerations and decelerations. A drive belt can be used instead of a drive chain in applications where noise suppression is desirable.  
         [0019]    A swing arm  132  can be used to couple the rear wheel  128  to the frame  104 . A shock absorber  134  can be coupled between the swing arm  132  and the frame  104  to absorb the energy produced by sudden bumps in the road. FIGS. 2A and 2B illustrate two exemplary mounting configurations with different frame attachment points. In the first case shown in FIG. 2A, the swing arm  132  is attached to the frame  104  above the electric motor  106 . In this configuration, the rear wheel axle follows a path along an arc  202  defined by a radius equal to the length of the swing arm  132  as the rear wheel  128  encounters bumps in the road during operation. This causes the radial length  204   a - c  between the electric motor drive shaft and the rear wheel axle to change accordingly. As a result, the drive belt  135  pulls taut when the rear wheel  128  moves upward and loosens up when the rear wheel  128  moves downward. An idler tensioner  206  can be used to regulate the belt tension.  
         [0020]    In the second case shown in FIG. 2B, the frame attachment point for the swing arm  132  is the electric motor drive shaft. In this configuration, the rear wheel axle again follows a path along an arc  208  defined by the radius of the swing arm  132  as the rear wheel  128  encounters bumps in the road during operation. However, since the frame attachment point for the swing arm  132  is concentric with the electric motor drive shaft, the radial length  210  between the electric motor drive shaft and the rear wheel axle remains unchanged with movement of the rear wheel  128 . As a result, the belt tension remains constant eliminating the need for the idler tensioner.  
         [0021]    [0021]FIG. 3 is a cross-section top view showing the mounting of the swing arm between the electric motor drive shaft and the rear wheel axle. The electric motor  106  can be held between the two frame members  104   a  and  104   b  with a motor support tube  302  bolted to the frame  104 . The back end  106   a  of the electric motor extends outward through an opening in one frame member  104   a.  The drive shaft  106   b  of the electric motor  106  extends outward through an opening in the other frame member  104   b.  A motor support ring  304  can be bolted to the electric motor  106  to achieve a face mount.  
         [0022]    The toothed pulley  136  can be connected to the distal end of the drive shaft  106   b . The drive belt (not shown) can be connected between the toothed pulley  136  and the toothed drive wheel  138  at the distal end of the rear wheel axle  128   a.  One end of the swing arm  136  can be connected to the drive shaft  106   b  through a front bearing  306   a.  The other end of the swing arm  136  can be connected to the rear wheel axle  128   a  through a rear bearing  128   b.  The drive shaft  106   b  should be sufficiently sized to support the swing arm  132 . A drive shaft with a diameter between ⅝″and ⅞″is a good choice, however, other shaft diameters may be used depending on the particular design requirements and performance tradeoffs ascertained by the skilled artisan.  
         [0023]    [0023]FIG. 4 is a side view of an exemplary electric motor driven cyclic with a cosmetic overlay around the frame. The overlay  402  can be plastic or any other suitable material. The use of a cosmetic overlay allows various overlay designs to be used without having to modify the frame. This approach may provide a very economical solution to support the evolution of aesthetic designs as the electric motor driven cycle industry continues to expand its penetration into the marketplace. The overlay  402  may include one or more bulges  404   a  and  404   b  to support the internal components of electric motor driven cycle. A drive belt and swing arm cover  406  in combination with the overlay  402  gives the electric motor driven cycle an overall aesthetically pleasing look.  
         [0024]    The electric motor driven cycle  102  may also include a front fender  408  to house the bifurcated member  116  of the front fork assembly  114  (see FIG. 1). A pod  410  can be used to house the clamp  124  connection between the steered tube  120  and the handle bar  126  (see FIG. 1). The pod  410  may also be used to carry various displays and controls depending on the particular design requirements and the intended consumer market. The pod  410  may also provide a convenient surface to support a headlight (not shown). The electric motor driven cycle  102  may also include a passenger seat  412  and front and rear foot pegs  414   a  and  414   b.    
         [0025]    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.