Abstract:
A motorized handle includes an elongate handle to which is attached a wheel and a motor to drive the wheel. A rider mounting a rolled conveyance, such as a skateboard or a pair of roller blades, may use the motorized handle to impart propulsion.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims benefit of priority to U.S. provisional application Ser. No. 60/639,957 filed on Dec. 22, 2004. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The invention pertains to self propelled devices, such as skateboards and the like, which are provided with a motor for self propulsion.  
         [0004]     2. Description of the Related Art  
         [0005]     Traditional skateboards, roller blades and roller skates operate on the principle of gravity to provide acceleration for a rider. Reliance upon gravity for motive force is problematic in that a rider may only ride downhill. For example, a skateboard must either be carried uphill to repeat the process or, if the surface is relatively flat, driven in a way that is quite awkward—the rider scoots along with one foot on the skateboard and the other foot contacting the ground in a quasi-walking mode. Absence of motorized propulsion precludes a wider range of use.  
         [0006]     Attempts have been made to install operative motors on skateboards, but these suffer from a variety of problems. It is problematic that the overall apparatus is relatively small, there is a need to temporarily disengage the motor from the drive assembly without a complicated transmission to perform this function, and the overall assembly must be steered in the manner of a traditional skateboard. By way of example, U.S. Pat. No. 5,381,870 issued to Kaufman shows a drive motor directed through a drive belt to a rear driven sprocket. U.S. Pat. No. 5,839,737 issued to Kruczek shows a motorized skateboard having a transmission that is actuated by the rider shifting weight on a fulcrum-lever, but this type of arrangement interferes with the rider&#39;s balance and may lead to loss of control.  
         [0007]     There remains a need to provide an improved motorized skateboard where the motor may be selectively engaged to drive the wheels.  
       SUMMARY  
       [0008]     The present instrumentalities overcome the problems outlined above and advance the art by providing a motorized handle that has a selectively engageable drive mechanism. This advantageously permits a rider to grasp the motorized handle and impart propulsion to a rolled conveyance.  
         [0009]     The motorized handle may include an elongate handle presenting an upper end and a lower end. A wheel is attached to the handle proximate to the lower end. A motor is attached to the handle proximate the wheel. A drive mechanism extends between the motor and the wheel, such that the drive mechanism configured to impart motive force to the wheel.  
         [0010]     By way of example, the motor may be an air cooled gasoline engine that is equipped with a centrifugal clutch. The centrifugal clutch may drive a shaft that resides in frictional contact with the wheel. A clamp assembly may be used to adjust the strength of the frictional contact between the shaft and the wheel. The handle may be an extensible handle that is formed in at least two telescoping segments and retained in a fixed length by a clamp.  
         [0011]     A method for a rider to propel a rolled conveyance includes the rider mounting the rolled conveyance. The rider grips the motorized handle and places the wheel on the ground for application of motive force. The motive force is imparted to the rolled conveyance through the rider&#39;s body and is used to propel the rolled conveyance. The rider may use the motive force as an aid to steering, an aid to travel, and an aid to balance.  
         [0012]     The rolled conveyance may be, for example, a skateboard, a pair of roller blades or roller skates, a bicycle, a scooter or a wheelchair 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  shows a rider who is using a motorize handle to propel a skateboard;  
         [0014]      FIG. 2  is a front elevational view of the motorized handle and provides additional detail with respect to  FIG. 1 ;  
         [0015]      FIG. 3  is a left side elevation view of the motorized handle and provides additional detail with respect to  FIG. 1 .; and  
         [0016]      FIG. 4  is a front view of the rider using the motorized handle. 
     
    
     DETAILED DESCRIPTION  
       [0017]     The present teaching is by way of example to illustrate the preferred embodiments.  
         [0018]      FIG. 1  shows a motorized handle  100  that permits a rider  102  to propel a conventional skateboard  104 . The motorized handle contains a selectively engageable drive mechanism  106 . The selectively engageable drive mechanism  106  is operable in two modes, namely, a coasting mode and a drive mode that the rider  102  may use to propel the skateboard  104  forward in the direction of arrow  108 . The rider  102  is able to engage the selectively engageable drive mechanism  104  and enter drive mode, for example, by depressing a throttle lever  110  that causes engine  112  to accelerate. The engine  112  is equipped with a centrifugal clutch (not shown) that causes the engine  112  to impart motive force for revolution of wheel  114 .  
         [0019]     The skateboard  104  is of conventional design, for example, having two sets of wheels  116 ,  118  connected to board body  120 . The motorized handle  100  is preferably not connected by a mechanical linkage to the motorized handle  100 , although it is also contemplated that a direct mechanical linkage of this type may be provided. Thus, the rider  102  may grip the handle section  122  as shown as an aid to drive, steering and balance against the ground  124 . The rider  102  may move or reposition the motorized handle  100  to a variety of positions including positions that are forward, rearward, laterally to the left and/or laterally to the right compared to what is shown in  FIG. 1 . The motorized handle  100  is placed in a coast mode by releasing the throttle lever  110  to disengage the centrifugal clutch.  
         [0020]      FIG. 2  shows the motorized handle in front elevational view and provides additional detail with respect to  FIG. 1 . Motor  112  is suitably, for example, an air-cooled two cycle internal combustion engine having 21 cubic centimeters of displacement and equipped with a centrifugal clutch. Motors of this type may be found, for example, on conventional hand held motorized grass trimming apparatus, such as equipment sold by Toro or Lawnboy. The centrifugal clutch, which is shown generally as  200 , operates on the principle of centrifugal expansion of a spring-biased radial member (not shown) to engage internal structures for drive actuation of shaft  108 . The centrifugal expansion occurs sufficiently for this purpose when the engine  112  is accelerating past a design threshold for drive engagement. An engine of this type that is equipped with a centrifugal clutch is, by way of example, shown and described in U.S. Pat. No. 6,773,375 issued to Nagashima, which use incorporated by reference to the same extent as though fully disclosed herein. The centrifugal clutch mechanism selectively engages a shaft  202  depending upon the speed of rotation in engine  112 . It is also possible to use, for example, other types of motors, such as battery powered motors that are used on lawn trimming apparatus. In the case of electric motors, which are advantageously quieter but may have short service lives between charges, the speed of rotation may be electronically controlled and a centrifugal clutch is not needed.  
         [0021]     The shaft  202  presents an outer surface  204 , which is in direct contact with radially outboard surface  206  of wheel  114 . Motive force from the shaft  202  transfers to wheel  114  by frictional engagement between the respective surfaces  204 ,  206 , commensurate with rotation of shaft  202  to drive wheel  114 . The motor  112  may be cranked by hand crank cord  208  and selectively accelerated by actuation of throttle  110  (not shown). Accordingly, the rider  102  selectively uses the speed of rotation in motor  112  to place the motorized handle in coast mode or drive mode by the actuation of throttle lever  110  and, indirectly, the centrifugal clutch  200  to impart motive force to the wheel  114  through shaft  108 .  
         [0022]     Motor  112  mounts to lower handle section  210  by the provision of adapter clamp assembly  212 , which couples the motor  112  and lower handle section  210  with a wheel segment  214 . The precise construction of clamp assembly  212  is unimportant, so long as the clamp assembly  214  conformably adapts, for example, to the motor  112  for attachment to lower segment  210  and/or the wheel segment  214 . Wheel  114  is connected by spokes  216  to a central hub  220 . An axle  222  connects the hub  220  to the wheel segment  214  by extension through aperture  224  and is retained by nuts  226 ,  228 .  
         [0023]     The lower segment  210  is tubular and rises towards an extension clamp  230 . Top member  232  is telescoping received within the lower segment  210 . Adjustment of the clamp assembly  230  permits extension and de-extension of the handle section  122  by axial sliding motion of top member  232  relative to the lower segment  210 . The top member  232  is optionally provided with a grip  234  to assist the rider  102  in using the motorized handle  100 .  
         [0024]     The shaft  202  and wheel  114  have different outer circumferences at surfaces  204 ,  206 . A drive ratio is defined as the ratio of these circumferences. The drive ratio may vary as a matter of design choice, but should not be so low that the motor  112  stalls when in drive mode or so high as to propel a rider uncomfortably fast. The drive ratio should not be so low that the maximum speed is boring to the rider. A drive ratio of about 30:1 (wheel  114  to shaft  202 ) is most preferred in the class of low power gasoline engines. In practice, this ratio has been found to strike a good balance between these design criteria for a 21 cubic centimeter motor  112  when drive wheel  114  has a sixteen inch diameter. The drive ratio may suitably vary in a preferred range from 10:1 to 30:1 for teenagers and adults, and from 10:1 to 20:1 for younger people.  
         [0025]      FIG. 3  is a left side elevational view of the motorized handle  100  and provides additional detail with respect to  FIG. 1 . The throttle lever  110  is coupled with a Bowden cable  300  for throttle control of motor  112 . The clamp assembly  212  is coupled with wheel segment  214  by a pivot  302  and a bolt  304 . The bolt  304  ride over a slot  306  and may be untightened for sliding  308  of the wheel segment  214  relative to the clamp assembly  212  with commensurate pivoting motion around pivot  302 . This pivoting motion, as translated to motor  122  through clamp assembly  212 , brings surface  204  into contact with surface  206  with sufficient strength for frictional drive according to the principles discussed above.  
         [0026]     In operation, the rider  102  starts the motor  112  and grips the handle section  122 . The rider is shown in  FIG. 1  as standing on a skateboard  104 , but there may also be used roller skates, roller blades, scooters, or other such rolling devices as wheelchairs. The rider  102  actuates throttle lever  110  to enter drive mode or coast mode, according to the rider preference. The rider  102  may use the motorized handle as an aid to steering or balance, in addition to providing motive force for propulsion. By way of example, motive force of wheel  114  against the ground  124  is transmitted through rider  122  to the skateboard  104 .  
         [0027]     As shown in  FIG. 4 , the rider  102  may alter his body position while using the motorized handle  100 . The motorized handle may, for example, be twisted on arc  400  so that propulsion from wheel  114  is off-axis from the direction of skateboard  104 . This twisting may be accompanied by the rider  102  leaning towards motorized handle  100  so as to place weight on the motorized handle  100  and turn the skateboard  104  for a left turn or to lean away to remove weight from motorized handle  100  for a right turn. The rider  102  may reposition the wheel away from the skateboard  104 , closer to the skateboard  104 , or to a location that is relatively forward or rearward of the position indicated in  FIG. 4 . The rider  104  may crouch or stand taller than the position shown in  FIG. 4 . These variations are provided to show that the motorized handle  100  may be repositioned to an infinite number of locations as may suit the desires of rider  102  and that the motorized handle  100  may receive different amounts of weight at different points in time to facilitate propulsion according to the rider&#39;s desire.  
         [0028]     Those skilled in the art will appreciate that the foregoing description teaches by way of example and not by limitation. The disclosed embodiments may be subjected to insubstantial changes that fall within the scope and spirit of the invention. As to these changes, the inventor hereby states his intention to rely upon the Doctrine of Equivalents to protect the scope and spirit of the invention.