Abstract:
An electrical bicycle includes a front body unit, a rear body unit and a pivot coupler unit which couples the front body unit and the rear body unit. The coupler unit enables the front body unit to be turned relative to the rear body unit when the rider turns his or her body to shift his or her center of gravity.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to bicycles and, more particularly, to an electrical bicycle, which enables the user to change the steering direction by biasing his or her body. 
     2. Description of the Related Art 
     A conventional bicycle, as shown in FIG. 1 is generally comprised of a head tube, a seat tube, a bottom bracket fixedly provided at the bottom side of the seat tube, a top tube and a down tube connected between the head tube and the seat tube, a handlebar and front fork assembly installed in the head tube to hold a front wheel, seat stays and chain stays backwardly extended from the seat tube and the bottom bracket, a rear wheel pivoted to the connection area between the seat stays and the chair stays, and a bottom bracket bearing axle, two pedal and crank assemblies respectively connected to the ends of the bottom bracket bearing axle, and a chain transmission mechanism coupled between the bottom bracket bearing axle and the rear wheel. When riding the bicycle, the rider pedals the pedal and crank assemblies to move the bicycle and operates the handlebars of the handlebar and front fork assembly to control the steering direction of the bicycle. There are known electrical bicycles in which a battery-operated motor drive is installed and controlled to rotate the front wheel (or rear wheel) of the bicycle. When operating these conventional bicycles, the rider controls the steering direction by means of operating the handlebars. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an electrical bicycle which enables the rider to control the steering direction of the bicycle by turning his or her body to change the center of gravity. It is another object of the present invention to provide an electrical bicycle which enables the rider to control the steering direction of the bicycle by turning his or her body to change the center of gravity with less effort than in a conventional bicycle. It is still another object of the present invention to provide an electrical bicycle which, which is durable in use. It is still another object of the present invention to provide an electrical bicycle, which is easy to assemble. It is still another object of the present invention to k provide an electrical bicycle, which has a receiving chamber for storing the battery module, tools, and parts. To achieve these and other objects of the present invention, the electrical bicycle comprises a front body unit, a rear body unit, and a pivot coupler unit coupled between the front body unit and the rear body unit for enabling the rider to control the direction of steering by twisting the body. The pivot coupler unit comprises a inverted T-shaped bar disposed vertically, a bottom bracket fixedly transversely fastened to a bottom side of the T-shaped bar, the bottom bracket having two ends fixedly connected to the rear body unit, a foot bar supported in the bottom bracket and protruded over two distal ends of the bottom bracket, a smoothly arched guard extended over the periphery of the T-shaped bar and fixedly fastened to the front body unit for enabling the front body unit and the rear body unit to be biased relative to each other, and a seat assembly coupled to a top end of the T-shaped bar. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic drawing showing the structure of a conventional bicycle. 
     FIG. 2 is a perspective view of an electrical bicycle according to the present invention. 
     FIG. 3 is an exploded view of the electrical bicycle according to the present invention. 
     FIG. 4 is a plain view of the electrical bicycle according to the present invention. 
     FIG. 5 is a schematic drawing showing a rider riding the electrical bicycle according to the present invention. 
     FIG. 6 is a top view of the present invention showing the front body unit and the rear body unit of the electrical bicycle aligned in a line. 
     FIG. 7 is a top view of the present invention showing the front body unit turned to the right. 
     FIG. 8 is a top view of the present invention showing the front body unit turned to the left. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 2, an electrical bicycle in accordance with the present invention is shown comprised of a front body unit  1 , a rear body unit  5 , and a pivot coupler unit  6  coupled between the front body unit  1  and the rear body unit  5 . 
     The pivot coupler unit  6  comprises a T-shaped bar  60  invertedly disposed in a vertical orientation, a bottom bracket  61  fixedly fastened to the bottom side of the T-shaped bar  60  in transverse direction, the bottom bracket  61  having two ends fixedly connected to the rear body unit  5 , a foot bar  62  supported in the bottom bracket  60  and protruding over the ends of the bottom bracket  60 , a smoothly arched guard  67  extending over the periphery of the T-shaped bar  60  and fixedly fastened with two ends thereof to the front body unit  1  for the purpose of enabling the front body unit  1  and the rear body unit  5  to be biased relative to each other, and a seat assembly  69  coupled to the top end of the invertedly disposed T-shaped bar  60 , a seat tube  66  fastened to the other end of the support arm  63 , and a saddle  65  supported on the seat tube  66 . 
     Referring to FIGS. 2-4 the front body unit  1  comprises two triangular flat side frames  10 ; 10 ′. The side frames  10 ; 10 ′ each have a front wheel coupling end  11  respectively connected to the ends of the wheel axle  21  of a front wheel  20 , a top handlebar coupling end  12  respectively connected to a head assembly  30 , and a rear coupling end  13  respectively connected to the ends of the guard  67  by connecting rods  131 . A plurality of transverse rod members  14  are connected between the side frames  10 ; 10 ′ by screws  141  and arranged along an imaginary arched line around the periphery of the front wheel  20  to support a fender  15  for protection against splashing mud. The fender  15  has two distal ends rolled up and respectively hooked on the first and last (the top and bottom) transverse rod members  14 . A bottom plate  16  is provided between the side frames  10 ; 10 ′ at the bottom side, having two distal ends respectively fixedly fastened to the last (bottom) transverse rod member  14  and the bottom-side connecting rod  131 . The side frames  10 ; 10 ′, the fender  15 , and the bottom plate  16  define a receiving chamber  19 . A battery module  40  is installed in the receiving chamber  19  to provide the bicycle with the necessary working power. A sliding cover plate  18  is coupled to the side frames  10 ; 10 ′ at the top, and disposed to close/open the receiving chamber  19 . 
     The aforesaid head assembly  30  comprises: a locating block  31  fixedly connected between the top handlebar coupling ends  12  of the side frames  10 ; 10 ′ by screws  311  and arranged in parallel to the sliding cover plate  18 , a head tube  32  fixedly connected to and obliquely forwardly extended from the locating block  31 , a handlebar stem  33  fixedly connected to the front end of the head tube  32 , a handlebar  34  transversely supported on the handlebar stem  33  at the top, two grips  35 ; 35 ′ respectively provided at the ends of the handlebar  34  and two brake levers  36 ; 36 ′ respectively pivotally connected to the grips  35 ; 35 ′. 
     Referring to FIGS. 2 through 4, the rear body unit  5  comprises two rear forks  50 ; 50 ′ bilaterally connected between the bottom bracket  61  of the pivot coupler unit  6  and the wheel axle  52  of a rear wheel  51 , a shock-absorber  54  fixedly mounted between the rear forks  50 ; 50 ′ and coupled to the bottom side of the support arm  63  of the seat assembly  69  between the T-shaped  60  and the seat stem  66 . 
     When riding the bicycle as illustrated in FIG. 5, the rider sits on the saddle  65  with the feet rested on the ends of the foot bar  62  and the hands holding the grips  35 ; 35 ′ and then the power switch (not shown) of the electrical bicycle is switched on enabling the rider to control the supply of batter power from the battery module  40  to the wheel hub motor  22  of the front wheel  20  or the wheel hub motor  53  of the rear wheel  51  to propel the electrical bicycle. During riding, the shock absorber  54  absorbs shocks, eliminating or reducing transmission of shocks to the saddle  65 . 
     The steering control of the electrical bicycle is outlined hereinafter with reference to FIGS. 6 through 8. FIG. 6 illustrates the electrical bicycle running forward in a straight line. At this time, the rider keeps his or her body vertical and the center of gravity is at the electrical bicycle. The pivot coupler unit  6  keeps the front body unit  1  and the rear body unit  5  aligned. FIG. 7 illustrates the electrical bicycle turned rightwards. At this time, the rider&#39;s upper body is slightly twisted to the right, the center of gravity of the rider&#39;s body is shifted to the right side of the electrical bicycle. Due to the change of the center of gravity, the angular position of the front body unit  1  is changed relative to the rear body unit  5 . When the rider twists his or her upper body to the left, the center of gravity is shifted to the left side, thereby causing the front body unit  1  to be turned to the left relative to the rear body unit  5  as shown in FIG.  8 . 
     As indicated above, controlling the steering direction is not through the handlebar  34 . Twisting the rider&#39;s body to change the center of gravity achieves the steering control. The grips  35 ; 35 ′ and the handlebar  34  are provided for the holding of the rider&#39;s hands and stabilizing the movement of the electrical bicycle but not for controlling the steering direction of the electrical bicycle. In order to let the rider control the steering of the electrical bicycle by twisting the body easily with less effort, the weight of the rear body unit  5  must be as low as possible. Further, the design of the front body unit  1  is strong. The user can easily install the front body unit  1 . When the sliding cover plate  18  is open the user can access the inside of the receiving chamber  19  to maintain or pick up internal members. When the sliding cover plate  18  closed, it protects the internal members inside the receiving chamber  19 . 
     While only one embodiment of the present invention has been shown and described, it will be understood that various modifications and changes could be made thereunto without departing from the spirit and scope of the invention disclosed.