Patent Publication Number: US-2003221888-A1

Title: Motor retrofit for scooter

Description:
PRIORITY CLAIM  
     [0001] This application claims priority from U.S. Provisional Patent Application No. 60/385,698, filed on Jun. 4, 2002, and this application claims priority from U.S. Provisional Patent Application No. 60/384,053, filed on May 29, 2002. Each of these provisional patent applications is being incorporated herein by this reference. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention generally relates to a device that converts a manual push scooter into an electrically powered scooter. More specifically, an embodiment of the present invention is a retrofit kit that includes a motor assembly to frictionally drive a wheel of the scooter.  
       BACKGROUND OF THE INVENTION  
       [0003] Most scooters are designed and manufactured primarily for recreational use. Manually powered scooters are well known as efficient means for transportation. Such scooters are propelled by the rider using a single stride with one leg, while the other leg and foot are maintained in contact with the rider platform. The front wheel of the scooter is steered by a handle bar that is also connected to the platform. Most commonly, a push scooter has a foot brake located proximate to and above the rear wheel. A rider may slow the scooter down by depressing the foot brake downward, bringing the foot brake into contact with the rear wheel and frictionally slowing the rotation of the rear wheel.  
       [0004] An example of a folding collapsible push scooter is shown in FIG. 1. The scooter  10  includes a footboard  11 , a rear wheel  14 , a foot brake  16 , a front fork assembly  18 , a collapsible connecting bar  22 , a front wheel  24 , and a handle bar  26 . The footboard  11  is the main area where the rider stands while driving or operating the scooter. The handle bar  26  is mounted to and supported by the connecting bar  22 . The connecting bar  22  is pivotally mounted onto the fork assembly  18 , allowing a rider to turn the front wheel  24  left and right. The connecting bar  22  may telescope up and down, allowing the rider to adjust the height of the handle bar  26 . The rear wheel  14  is secured relative to the footboard  11  by a rear axle  30  mounted through a rear fork  32  extending rearwardly from footboard  11 . The foot brake  16 , as shown in FIG. 1, is commonly located over the rear wheel  14 , so that the rider may easily keep one foot on the footboard  11  while the other foot operates the foot brake  16 .  
       [0005] One reason the scooter is so popular is that the scooter can be folded into a compact structure, making it easy to carry and store when not in use. For example, the fork assembly  18  may pivot between an operative or extended position, as shown in FIG. 1, and a non-operative or collapsed position where the connecting bar  22  is substantially parallel to the footboard  11 .  
       [0006] Electrically powered scooters have begun to replace push scooters. An electric scooter eliminates the need for the rider to push on the ground to propel the scooter forward. Instead, the rear wheel is electrically driven when a throttle assembly, commonly located on the handlebar, is activated by the user. A manual foot brake is still commonly used to frictionally slow the scooter down. Over the years, the electrically powered scooter has become the preferred type of scooter.  
       [0007] There are still many manual push scooters on the market today. For example, the Razor™ scooter has several models of manual push scooters such as the RZ Cruiser™ and the RZ Ultralite™. Such scooters are being used today. Owners of a manual push scooter may not wish to buy a new, more expensive electric scooter. Thus, there is a need to provide an apparatus to convert existing manual push scooters into electrically powered scooters at a low cost.  
       SUMMARY OF THE INVENTION  
       [0008] An aspect of the present invention is to provide an apparatus that can attach to a manually powered scooter and convert the manual push scooter into an electrical scooter. An embodiment of the present invention connects to the rear fork of the manually powered scooter. Once attached, a roller frictionally engages and drives the rear wheel to propel the scooter.  
       [0009] Another aspect of the present invention is to attach an apparatus to a scooter that will not require modifying any of the existing components. An embodiment of the present invention does not reduce the existing footboard space that a user stands on when riding the scooter or alter the existing foot brake system of the scooter.  
       [0010] In a further aspect of the invention, the motor is mounted between a floorboard and a rear wheel, with a foot brake located aft of the motor.  
       [0011] Yet another aspect of the present invention is to allow a user to electrically control the speed of the scooter. An embodiment of the present invention includes a throttle assembly that mounts onto the handlebar of the scooter. In this embodiment, a throttle handle is electrically connected to a motor assembly and a battery. The speed of the motor is controlled by activating the throttle handle.  
       [0012] Still another aspect of the present invention is to provide an apparatus that has easily replaceable parts. An embodiment of the present invention has a removable friction roller that can be replaced when it degrades or wears out. Another embodiment of the present invention has a removable battery housing so that a battery stored within the housing can be conveniently removed and recharged.  
       [0013] Another embodiment of the present invention has a motor cut-off switch that will prevent the rider from burning out or destroying the motor. In one embodiment, the motor is electrically isolated from the battery and throttle assembly when the foot brake is activated.  
       [0014] A further embodiment of the present invention is to allow a rider the flexibility to either manually push the scooter or electrically propel the scooter. One embodiment has a roller positioning mechanism for holding the roller against the rear wheel or maintaining the roller away from the rear wheel.  
       [0015] Further, an embodiment of the invention includes a robust attachment device to secure the battery and also the motor to the scooter.  
       [0016] Other aspects and features of the invention can be found in the specification, drawings and claims. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0017]FIG. 1 is a perspective view of a folding collapsible push scooter, according to the prior art.  
     [0018]FIG. 2 is a perspective view of an embodiment of the present invention attached to the push scooter shown in FIG. 1.  
     [0019]FIG. 3 is a partial exploded view of the embodiment of the present invention shown in FIG. 2.  
     [0020]FIG. 4 is an exploded view of an embodiment of the motor assembly of FIG. 3, according to the present invention.  
     [0021]FIG. 5 is a perspective view illustrating the roller removed from the motor assembly of the embodiment of FIG. 2 of the invention.  
     [0022] FIGS.  6 A- 6 C, FIG. 6A is a top view of the embodiment of FIG. 2 of the present invention in an engaged position; FIG. 6B is a side partial cutaway view along line C-C in FIG. 6A; FIG. 6C is a sectional view of area D indicated in FIG. 6B.  
     [0023] FIGS.  7 A- 7 C, FIG. 7A is a top view of the embodiment of FIG. 2 of the present invention in a disengaged position; FIG. 7B is a side partial cutaway view along line B-B shown in FIG. 7A; FIG. 7C is a sectional view of area E shown in FIG. 7B.  
     [0024]FIG. 8 is a perspective view of an alternate embodiment of the motor assembly of the invention.  
     [0025]FIG. 9 is a side view of the alternate motor assembly of the invention shown in FIG. 8.  
     [0026]FIG. 10 is a sectional view of the motor assembly of the invention shown in FIG. 8.  
     [0027]FIG. 11 is a perspective view of the internal components of the motor assembly of the invention shown in FIG. 8.  
     [0028]FIG. 12 is a perspective view of the internal components of the motor assembly of the invention shown in FIG. 8 in a disassembled state.  
     [0029]FIG. 13 is an exploded perspective view of a battery and a battery mount of an embodiment of the invention.  
     [0030]FIG. 14 is a perspective view of a battery of the embodiment of FIG. 13 of the invention mounted on the battery mount shown in FIG. 13. 
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION  
     [0031] The present invention will be described in reference to FIGS.  2 - 14 . FIG. 2 illustrates the retrofit kit  100  attached to the rear fork  32  of the scooter. The retrofit kit  100  includes a mounting bracket  102 , a battery housing  104  and a motor assembly  106 . The mounting bracket  102  is the main support for both the battery housing  104  and the motor assembly  106 . In a preferred embodiment, as shown in FIG. 2, the retrofit kit  100  mounts on the rear fork  32  and extends from the rear of the scooter. This design does not require modifying any of the parts of the scooter, and does not interfere with the operation of any of the parts of the scooter. For example, the mounting bracket  102  forms around the rear tire  14  and the foot brake  16  when mounted to the scooter. As the mounting bracket  102  is the main structure to support all the components of the retrofit kit  100 , the mounting bracket  100  should be a rigid structure. The mounting bracket  102  may be manufactured from materials such as, but not limited to, aluminum, steel, and stainless steel. It is within the scope of the present invention for the mounting bracket  100  to be manufactured from other materials.  
     [0032] The mounting bracket  102  secures to the scooter by two flanges  108 . In one embodiment, each flange  108  has a “U”-shaped channel  110  located on the interior of each end  111 . The width of each “U”-shaped channel  110  is preferably slightly larger than the width of each rear fork  32 . Additionally, the distance between the two flanges  108  is preferably substantially similar to the width between the rear forks  32 . These dimensions allow each “U”-shaped channel  110  to slide over the outside surface of the rear fork  32 , yet at the same time provide a rigid connection between the bracket  102  and the rear fork  32 . As shown in FIG. 2, the platform  103  that the battery housing  104  is secured to is horizontal. However, it is within the scope of the present invention for the platform  103  to be at an angle when the bracket  102  is mounted on the scooter.  
     [0033] The mounting bracket  102  is held stationary relative to the scooter by the rear axle  30 . That is, the mounting bracket  102  cannot slide onto the rear fork  32  while the rear axle  30  is in place. To install the bracket  102 , a user should first remove the rear axle  30 . Removing the rear axle  30  disengages the rear wheel  14  from the rear fork  32 . After removing the rear axle  30 , the user should align the channels  110  with the rear forks  32  and slide the flanges  108  over the rear forks  32  until the bore  112  in the flange  108  aligns with the axle hole in the rear fork  32 . Once the mounting bracket  102  is aligned with the rear fork  32 , the rear axle pin  30  may be re-inserted. In effect, the rear axle  30  functions as the rotation axis for the rear wheel  14  and prevents translation of the bracket  102  relative to the scooter.  
     [0034] The power for the retrofit kit  100  is supplied by a battery  156  (see FIGS. 6B and 7B). The above battery housing  104  encases the battery  156 . The battery housing  104  prevents an individual from accessing and touching the battery terminals. In the embodiments shown in FIG. 2 as described above, the bracket  102  has a platform  103  that the battery housing  104  mounts to, and rests upon. As shown in FIG. 3, an alternate embodiment of the battery housing  104  is a two-piece container. By way of example only, the housing  104  may be manufactured from ABS plastic. In one embodiment, the two halves of the housing are ultrasonically welded together to form a single unit. However, in alternate embodiments, the two halves of the housing  104  may be fastened together by any method as long as the halves can be repeatedly separated (e.g., fasteners, clamps or bolts). Methods to attach and repeatedly separate two halves of a housing are known to those skilled in the art. In the embodiment shown in FIG. 3, the housing  104  has an access hole (not shown) in the side or bottom to allow the cable  162  (FIG. 2) to enter the battery housing  104  and electrically connect to the battery  156 . In one embodiment, the battery  156  is secured within the housing  104  so that the battery  156  will not move or slide around within the battery housing  104  during operation of the scooter. For example, scooters are driven on many different types of terrain, such as on smooth streets and bumpy sidewalks. The housing  104  is preferably fastened to the platform  103  to prevent the housing  104  from falling or sliding off the platform  103  during operation of the scooter. By way of example only, the housing  104  may be attached to the platform  103  by a latch, a bolt or any other type of fastening mechanism. Alternate embodiments can include a fastening plate  105  that attaches to the housing  104  and the platform  103  (see FIG. 3). In one embodiment, the fastening plate  105  and the housing  104  have a quick-release mechanism, allowing the user to easily disconnect the plate  105  or the housing  104  from the bracket  102 .  
     [0035]FIG. 4 illustrates one embodiment of the components of the motor assembly  106 . In the embodiment shown in FIG. 4, a motor housing, comprised of a first half  120  and a second half  122 , encloses and supports a motor  114 , a roller  116  and a torsional spring  118 . The first half  120  of the motor housing has a motor shaft bore  124 , a support column  126 , and a pulley shaft bore  130 . When the motor housing is assembled, the bore  124  aligns with the motor shaft  135 . The motor shaft  135  passes through the bore  124  and extends out of the motor housing. The support column  126  has a cavity that a first end  127  of the pivot shaft  128  extends into such that the pivot shaft  128  can rotate within the support column  126 . In the embodiment shown in FIG. 4, the pulley shaft bore  130  is located below the pivot shaft  128  and aligns with the second timing belt pulley  132 .  
     [0036] The second half  122  of the motor housing is a mirror image of the first half  120  and includes a motor support, a support column  138 , and an axle bore  140 . The motor support aligns with the stationary motor shaft  135 . Thus, the motor  114  is supported by the motor shaft bore  124  and the motor support  134  when the first half  120  and second half  122  are secured together. The support column  138  has a cavity similar to the support column  126  for accepting the second end  129  of the pivot shaft  128  and the bore  140  aligns with, and supports, the axle bearing  142 .  
     [0037] The rotating shaft  135  of the motor  114  extends through the bore  124  of the first section  120  and engages a first timing belt pulley  131 . The timing belt pulley  131  is secured to the shaft  135  and therefore rotates at the speed of the shaft  135 . In operation, the motor shaft  135  drives the first timing belt pulley  131  in a clockwise direction. By way of example only, a motor suitable for the motor assembly  106  is manufactured by Mabuchi Motor, Model No. RS-775 or RS-500 series. The first timing belt pulley  131  drives the second timing belt pulley  132  by a timing belt  142  that frictionally engages both the first pulley  131  and the second pulley  132 . Thus, the first pulley  131  and second pulley  132  rotate in the same direction.  
     [0038] The two pulleys  131  and  132  operate as a gear reduction mechanism so that the roller  116  will rotate at a slower speed than the motor shaft  135 . For example, and as shown in FIG. 4, the diameter of the pulley  132  is larger than the diameter of the pulley  131 . As previously mentioned, the pulley  131  rotates at the speed of the motor shaft  135 . In a preferred embodiment, the diameter of the second pulley  132  is five to eight times larger than the diameter of the first pulley  131 . Accordingly, the second pulley will rotate five to eight times more slowly than the first pulley  131 .  
     [0039] The second pulley  132  has a shaft  133  that extends through the bore  130  and into the motor housing when the motor assembly  106  is assembled. The bore  130  is larger than the shaft  133  so that the pulley  132  may rotate freely. In one embodiment, the shaft  133  is maintained substantially parallel to the motor shaft  135 . A bearing  150  is press fit into a bearing seat (not shown) located within the outer pulley  132  so that the bearing  150  and the pulley  132  rotate as a single object. A drive belt  143  connects first pulley  131  and second pulley  132 .  
     [0040] In the embodiment shown in FIG. 4, the bearing is rotatably mounted onto a stem  152  extending from the protective cover  154 . However, in alternate embodiments, the pulley  132  can mount directly onto the stem  152 . In either case, the central axis of rotation of the pulley  132  is the stem  152 . The protective cover  154  attaches to the first half  120  of the motor housing and remains separated from the outer surface of the motor housing so that it does not interfere with the operation of the pulleys  131  and  132  or the timing belt  142 .  
     [0041] The roller  116  has a cavity to engage the shaft  133 . As shown in FIG. 4, the shaft  133  has a cruciform shape. However, in alternate embodiments, other interlocking or keyed shapes can be used. The cavity of the roller  116  should be shaped similarly to the shaft  133  and have substantially the same diameter such that the roller  116  and the shaft rotate as a single unit and that the roller  116  does not slide in response to, or independent from, the shaft  133 . Thus, the roller  116  will rotate at the same speed as the pulley  132 .  
     [0042] In the embodiment shown in FIG. 4, the roller  116  preferably remains in a substantially horizontal position at all times. To help maintain this position in one embodiment, the roller  116  is supported at both ends. As previously mentioned, one end of the roller  116  is mounted on, and rotates about, the stem  152 . An axle  142  extends from the other end of the roller  116 . The axle  142  extends through, and is rotatably seated within, the bore  140  and a bearing  144  is seated within the bearing seat  141  of the axle  142 . In one embodiment, the bearing  144  is press fitted into the bearing seat  141 . The bearing engages a stem  148  that protrudes from the access cover  146 . Similar to the bearing  150 , the bearing  144  is rotatably secured to the stem  148  so that the roller  116  may rotate freely. Accordingly, the roller  116  is ultimately supported by the stems  148  and  152 . The stems  148  and  152  are aligned along a concentric horizontal axis so that the roller  116  remains in a substantially perpendicular position in relation to the rear wheel  14  when the roller is in both the power-assist mode and the free-wheel mode (both described later).  
     [0043] In the power assist mode, the roller  116  frictionally contacts and drives the rear wheel  14  of the scooter. The continuous contact between the roller  116  and the rear wheel  14  will tend to wear the roller  116  down over time. The roller  116  is preferably manufactured from a material that will not easily degrade. The roller  116  may be manufactured from materials such as, but not limited to, steel or aluminum, to increase the life of the roller  116 , or also rubber, plastic, a polymer or an elastomeric material which, preferably, is softer than the rear wheel. The roller  116  has a track or channel  117 . In one embodiment, the track  117  is preferably shaped substantially similar to the contour of the rim of the wheel  14 . For example, the track  117  is substantially “U”-shaped to mirror the shape of the wheel  14  shown in FIG. 1. Since the roller  116  will experience wear and tear from the frictional contact with the rear wheel  14 , the roller  116  may need to be replaced from time to time.  
     [0044] As shown in FIG. 5, the motor assembly  106  is been designed so that the roller  116  can be easily replaced by the rider without having to remove the entire motor assembly  106  from the bracket  102 . To replace the roller  116 , the user can first place the scooter in the free-wheel mode (described hereinafter) by decoupling the roller  116  from the rear wheel  14 . The cover  146  can then be removed to access the roller  116 . In one embodiment, and as shown in FIG. 5, the cover  146  is secured to the motor assembly  106  by four screws. Once the cover  146  is removed, an individual can remove the worn-out roller by sliding the roller  116  off the pulley shaft  133  and out of the motor housing  106 . A new roller  116  can then be placed into the motor assembly  106  and onto the shaft  133 . After inserting a new roller, a user can replace the bearing  144  back into the bearing seat  141  and fasten the cover  146  to the motor assembly  106 .  
     [0045] The scooter can be operated in a free-wheel mode and a power-assist mode. When the roller  116  is placed in the power-assist mode (see FIGS.  6 B- 6 C), the track  117  of the roller  116  contacts the rear wheel  14  along its outer surface  15 . The shape and size of the rear wheel  14  will vary depending on the manufacturer and model of the scooter. For example, some scooters, such as the Razor™ models, use smaller wheels having a diameter of approximately five inches. Other scooters, such as a few models designed by The Sharper Image™, use larger wheels having a diameter of nine inches. Thus, the shape and size of the roller  116  can vary to accommodate the specific shape of the rear wheel  14 .  
     [0046] In one embodiment, there is a large contact area between the roller  116  and the rear wheel  14  to frictionally drive the rear wheel  14 . The frictional force is proportional to the contact area shared between the two surfaces. The larger the frictional force created between the roller  116  and the rear wheel  14 , the more efficiently the roller  116  will drive the rear wheel  14 . A larger frictional force will also prevent the roller  116  from slipping while driving the rear wheel. However, it is noted that the final linear speed of the rear wheel is independent of the size of the rear wheel.  
     [0047] A rider should still have the option to manually push the scooter. For example, if the battery  156  expires while riding the scooter, it would be beneficial if the rider could manually push the scooter and not have to overcome the resistance created by the roller  116  remaining in contact with the rear wheel  14 . The scooter can therefore operate in a free-wheel mode.  
     [0048] The torsional spring  118 , mounted on the shaft  128 , rotates to either hold the roller  116  against the rear wheel  14  (power-assist mode, FIGS.  6 A- 6 C) or keep the roller  116  away from the rear wheel  14  (free-wheel mode, FIGS.  7 A- 7 C). The shaft  128  is manually moved between the two positions by a lever (not shown) that is pivotally attached to and extending from the second half  122  of the motor housing  106 . The lever is mechanically attached to the pivot shaft  128  and can be moved between a power-assist mode or free-wheel mode location. The lever can be “locked” into either position. Such engagement and locking mechanisms are well known in the art.  
     [0049] In the power-assist mode the roller  116  is held against the rear wheel  14  by the force from the torsional spring  118  FIGS.  6 A- 6 C). FIG. 6B is a partial cross-sectional view of the motor assembly  106 , along extension line C-C in FIG. 6A. As shown in FIG. 6B, the roller  116  is held against the rear wheel  114 . In this position, the roller  116  will frictionally drive the rear wheel  14  when the throttle assembly  160  (to be described later) is activated. FIG. 6C illustrates a more detailed view of the roller  116  engaging the rear wheel  14 , as shown in area D in FIG. 6B. The roller  116  is spring-biased in this position during the power-assist mode. By activating the throttle assembly  160 , the roller  116  will rotate and drive the rear wheel  14 , propelling the scooter forward.  
     [0050] If the user wishes to manually push the scooter, the user can select the free-wheel mode. The user can mechanically decouple the roller  116  from the rear wheel  14  by rotating the housing against  104  the torsional spring  118  away from the rear wheel  14 . This action is accomplished by rotating the lever in the opposite direction that was required to place the scooter in the power-assist mode. By decoupling the roller  116  from the rear wheel  14 , the rear wheel  14  may rotate freely about the rear axle  21 . While the scooter is in the free wheel mode, the roller  116  is held away from, and is not in contact with, the rear wheel  14 . FIGS.  7 A- 7 C illustrate that the roller  116  is held away from the rear wheel  14  at all times during the free-wheel mode.  
     [0051] The retrofit kit  100  includes a throttle assembly  160  that electronically controls the rotation of the roller  116  (see FIG. 2). The throttle assembly  160  includes a cable  162  and an acceleration handle  164 . The cable  162  is electrically connected between an acceleration handle  164  and the battery  156 . In one embodiment, the cable  162  preferably travels down the connecting bar  22 , across the side of the platform  10  and along the mounting bracket  102  to the battery  156 . In one embodiment, the cable  162  is secured to the connecting bar  22 , the platform  10  and the mounting bracket  102  to prevent the cable  162  from getting caught or snagged on a passing object. In an alternate embodiment, the cable  162  is secured to the side or bottom of the platform  10  so that the user will have a flat surface to stand upon.  
     [0052] In one embodiment, the acceleration handle  164  is mounted to the handlebar  26  so that the rider may conveniently control the speed of the scooter while standing on the platform  10 . To activate the motor  135  and thus the roller  116 , the acceleration handle  164  may be pulled towards the handlebar  26 . When the handle  164  is pulled towards the handlebar  26 , the roller  116  begins to rotate and drive the rear wheel  14 . In one embodiment, the closer the acceleration handle  164  is pulled towards the handlebar  26  the faster the motor shaft  135  will rotate. Releasing the acceleration handle  164  to its “normal” position will electrically isolate to the motor  114  from the battery  156  and the motor will no longer drive the scooter. Such speed control is well known in the art. Positioning the acceleration handle  164  on the handlebar  26  allows a user to steer the scooter and control the speed of the scooter while maintaining both hands on the handlebar  26 . The acceleration handle  164  may be fastened to either side of the handlebar  26 . In alternate embodiments the acceleration handle  164  can be attached to other areas of the scooter or the acceleration handle  164  may be in the form of a foot peddle located on the platform  10  or any other convenient location of the scooter.  
     [0053] In most instances, the user may slow the speed of the scooter by releasing the acceleration handle  164 . As previously mentioned, releasing the handle  164  causes the roller  116  to stop driving the scooter. In fact, the roller  116  will provide a small braking force. The rear wheel  14  must be able to overcome the frictional force of the motor shaft  135  and pulley system to keep rotating. However, sometimes this braking force will not be sufficient to bring the scooter to a complete stop. For example, if the rider is traveling down a steep hill the scooter may continue to accelerate even though the acceleration handle  164  has been released. Similarly, if the rider needs to bring the scooter to a quick stop, releasing the acceleration handle  164  may not stop the scooter in a sufficiently short period of time.  
     [0054] The foot brake  16  provides an additional method to stop or slow the scooter. Stepping on the foot brake  16  brings the underside of the foot brake  16  in contact with the rear wheel  14 . This contact will slow the rotation of the rear wheel  14  and eventually bring it to a complete stop. In one embodiment, when the foot brake  16  is depressed, a motor cut-off switch interrupts the electrical signal to the motor  114  as previously mentioned, and electrically isolates the motor from the battery  156 . The switch prohibits the motor shaft from driving the roller  116  while the foot brake  16  is depressed, even if the handle  164  is pulled towards the handlebar  26 . This prevents the motor assembly  106  from driving the rear wheel  14  while the foot brake  16  is inhibiting rotation of the rear wheel  14 . If the foot brake  16  did not include a cutoff switch, the motor shaft  135  could continue to attempt to rotate the roller  116  even though rotation of the rear wheel  14  is being inhibited by the foot brake  16 . This could overheat and/or overload the motor  114 , reducing the life of the motor or damaging it permanently. Furthermore, switch will be in an open position when the scooter is in a “free wheel” mode. Thus, electrical power will not be transmitted to the motor when the scooter is in “free wheel” mode (see also switch  804  in FIG. 9).  
     [0055]FIG. 8 is an alternate embodiment of the motor assembly  106 . In the embodiment shown in FIG. 8, the motor assembly is inboard of the scooter rear wheel  14  rather than above or behind the rear wheel  14  of the scooter as described in the embodiment shown in FIGS.  2 - 7 . In the embodiment shown in FIG. 8, the motor assembly  106  is rigidly fixed to the footboard  10  of the scooter, but does not interfere with the foot brake  16 . In the embodiment shown in FIG. 8, the foot brake  16  also includes a pin  802  that extends from one side of the foot brake  16 . When the foot brake  16  is in its inactive (non-depressed) position, the pin  802  is in contact with a switch lever  804  that is associated with the motor assembly  106  which closes the circuit and allows electrical power to be delivered to the motor assembly  106 . When a user engages the foot brake  16  by depressing it, the pin  802  is moved out of contact with the switch lever  804  thus creating an open circuit and preventing delivery of electrical power to the motor assembly  106  and preventing the motor assembly  106  from driving the rear wheel  14 .  
     [0056]FIG. 9 shows an elevation view of the motor assembly  106  attached to the scooter shown in FIG. 8. In the embodiment shown in FIG. 9, when the foot brake  16  is in an inactive position (non-depressed), it is held out of contact with the wheel  14  by a torsional spring  902 . The torsional spring  902  is wound around a brake axle  904  and biased against both the foot brake  16  and at least one platform  906  on the rear fork  30 . In alternate embodiments, the foot brake  16  may be supported by other mechanisms known in the art or the torsional spring  902  may be biased against other sections of the scooter.  
     [0057] As described with regards to FIG. 8, when foot brake  16  is in an inactive position (non-depressed), the pin  802  is held in contact with the switch lever  804 . However, when the foot brake is depressed, the pin  802  is moved out of contact with the switch lever  804  and electrical power is not delivered to the motor assembly  106  to drive the wheel  14 . It is noted that the foot brake  16  is located aft of the motor  106  for convenience of operation. The user can rest his rear foot on the motor and when desired conveniently shift his rear foot aft to activate the foot brake.  
     [0058] In the embodiment shown in FIG. 9, the motor assembly  106  is pivotally mounted on a rotation axle  908 . The rotation axle  908  is connected to a support bracket  910  that is rigidly fixed to the scooter. In the embodiment shown in FIG. 9, the support bracket  910  is mounted to the scooter and primarily supported on the brake axle  904 . To prevent rotation of the support bracket  910  and motor assembly  106  around the rotation axle  908 , a front portion of the support bracket  910  rests against the upper surface of the foot board  10  and a rear portion  912  of the support bracket  910  rests on the upper side of the rear fork  30 . In the embodiment shown in FIG. 9, the front and rear portions of the support bracket are biased by a torsional spring such that downward pressure is applied to both the rear fork  30  and the upper surface of the foot board  10 . In alternate embodiments, the support bracket may be fixed to the scooter in various other manners.  
     [0059] In the embodiment shown in FIG. 9, the motor assembly  106  is biased by a torsional spring (not shown) such that the friction brushing (not shown) is pressed against the wheel  14 . However, in alternate embodiments other methods know in the art to hold the roller (not shown) in contact with the wheel  14  may be used.  
     [0060] The motor assembly  106  further includes a toggle locking pin  914 . The toggle locking pin  914  allows the motor assembly  106  to be moved from a first position to a second position and held in the second position. In a first position, the roller (not shown) is pressed against the wheel  14  such that rotation of the roller (not shown) can drive the wheel  14  and propel the scooter. In a second position, the roller (not shown) is held away from the wheel  14 , thus allowing the scooter to be used without assistance from the motor assembly  106 . In the embodiment shown in FIG. 9, when the motor assembly  106  is in a second position, the toggle pin  914  (FIGS. 11, 12) can engage a bore (not shown) in the mounting bracket such that the motor assembly is held in the second position. In one embodiment, the toggle pin  914  is spring biased such that when the toggle pin  914  is moved in a prescribed manner, the spring bias of the toggle pin  914  will drive it into the bore (not shown) in the mounting bracket when the motor assembly is in the second position. The toggle pin  914  may then be manually or automatically removed from the bore (not shown) so that the motor assembly may return to the first position.  
     [0061]FIG. 10 is a cross-sectional view of the motor assembly  106  and scooter shown in FIGS. 8 and 9. In the embodiment shown in FIG. 10, the motor assembly contains a roller  116  to frictionally drive the wheel  14  and a motor  114  to convert received electrical power into mechanical power to drive the roller  116 . FIG. 10 also shows that the brake  16  further includes a brake pad  1002 . In the embodiment shown in FIG. 10, the brake pad is removably attached to the brake  16  by two fasteners  1004 . However, in alternate embodiments, the brake pad may not be present, or may be fixedly attached to the brake  16 .  
     [0062]FIG. 11 is a perspective view of the interior of the motor assembly  116  shown in FIGS.  8 - 10 . In the embodiment shown in FIG. 11 the motor  114  includes a drive wheel  1102  that is connected to the drive spindle  1104  of the motor  114 . The drive wheel  1102  is affixed to the drive spindle  1104  such that it rotates with the same angular velocity as the drive spindle  1104  with little or no slippage. A drive belt  1106  connects the drive wheel  1102  to a roller driver  1108 . The drive belt  1106  frictionally engages both the drive wheel  1102  and the roller driver  1108 . The rotation of the roller driver  1108  rotates roller  116  about a roller axis  1110  which remains essentially stationary relative to the scooter. The roller  116  frictionally engages the wheel  14  to drive the scooter. The embodiment shown in FIG. 11 also includes a second roller  1112  which is removably attached to the roller axis  1110  and the roller  116 . The second roller  1112  is a spare roller that may be interchangeably switched with the roller  116 . In the embodiment shown in FIG. 11, an end cap  1114  that is removably attached to the roller axis  1110 .  
     [0063]FIG. 11 further shows an embodiment which includes a bias spring  1116  that is associated with the toggle pin  914 . The bias spring  1116  may be engaged such that the toggle pin  914  will be driven into a bore (not shown) in the mounting bracket  910  when the motor assembly  116  is in a second position, as described above with regards to FIG. 9.  
     [0064]FIG. 12 shows a perspective view of discrete components of one embodiment of the motor assembly  116 . The embodiment shown in FIG. 12 includes a keyed spindle  1202  that mounts on the roller axis  1110  and is free to rotate about the roller axis  1110 . The keyed spindle  1202  has a predetermined pattern that allows it to engage the bore within the roller  116  such that the keyed spindle  1202  can drive the roller  116 . The keyed spindle  1202  is also designed to mate with a first driver cam  1204  and a second driver cam  1206 . The opposite side of the first driver cam  1204  is keyed to mate with the roller driver  1108  and the opposite side the second driver cam  1206  is keyed to mate with and degage the bore of the second roller  1112 . A locking cam  1208  is keyed to mate with the portion of the second driver cam that passes through the bore of the second roller  1112  and engage the end cap  1114 . In the embodiment shown in FIG. 12, rotation of the roller driver  1108  causes rotation of the first driver cam  1204 , the keyed spindle  1202 , the roller  116 , the second driver cam  1206 , the second roller  1112 , the locking cam  1208  and the end cap  1114  about the roller axis  1110 .  
     [0065] In the embodiment shown in FIG. 12, the individual components may be easily removed by a user and replaced when worn or damaged. For example, if the roller  116  becomes worn, a user may wish to exchange the roller  116  with the second roller  1112 . The user may simply remove the end cap  1114 , locking cam  1208 , second roller 1112 second driver cam  1206 , roller  116 , drive spindle  1202  and first driver cam  1204 . The user may then disassemble the part and reassemble them with the roller  116  and second roller  1112  in the opposite locations then reinsert the assembly back along the roller axis  1110  and begin using the scooter again. Similarly, a user my replace any other worn or damaged piece associated with the drive spindle  1202 .  
     [0066] Although FIG. 12 describes a configuration in which all components coaxial with the roller axis  1110  rotate when the roller driver  1108  is rotated, in alternate embodiments one or more components that are coaxial with the roller axis  1110  may remain rotationally stationary when the roller driver  1108  is rotated, provided that the roller  116  rotates in a predetermined relationship to the roller driver  1108 . For example, in one embodiment, the second roller  1112  may remain rotationally stationary when the roller driver  1108  is rotated. Furthermore, in alternate embodiments, the second driver cam  1206  that engages the second roller  1112  may be rotationally isolated from the driver spindle  1202  by ball-bearing-type isolation between the side that engages the drive spindle  1202  and the side that engages the second roller  1112 . Thus, rotation of the drive spindle  1202  would not force rotation of the second roller  1112 , the locking cam  1208  or the end cap  1114 .  
     [0067] In yet another alternate embodiment, the side of the second driver cam  1206  that engages the second roller  1112  may not be keyed in the area in which the second roller is engaged. Thus, rotation of the second driver cam  1206  would not force rotation of the second roller  1112 .  
     [0068] To install the embodiment of the motor assembly  104  shown in FIGS.  8 - 11 , a user can remove the brake axle  904  and the existing foot brake  16 . The support bracket  910  together with the motor assembly  104  can then be positioned on the foot board  10  such that the rear portion  912  of the support bracket  910  rests on the rear fork  32  and the forward portion of the support bracket  910  rests on the rear end of the foot board  10 . The pivotal supports of the new foot brake  16  can then be aligned with the new support bracket along the axis from which the brake axle  904  was removed. The brake axle  904  can then be re-inserted in its original location of the scooter to secure the new foot brake  16 , support bracket  910 , and motor assembly  104  to the scooter. The user can then tension the torsional spring against the new foot brake  16  such that the foot brake  16  is held out of contact with the rear wheel  14 . The battery  156  and throttle control  164  can then be attached to the scooter in various locations and in various manners. The motor assembly  104 , battery  156  and throttle control  164  can then be electrically connected as desired.  
     [0069]FIG. 13 is a perspective view of a battery  1302  that is being mounted on the connecting bar  22  of a scooter. In the embodiment shown in FIG. 13, the battery  1302  has a mounting slot  1304  and a bore  1306 . The scooter has a mounting track  1308  that is removably attached to the connection bar  22  of the scooter by fasteners  1310  that frictionally retain the mounting track in position on the connection bar  22 . In alternate embodiments, the mounting track  1308  may also be designed to mate with a particular section of the connection bar  22  in a “pocket fit” manner. In the embodiment shown in FIG. 13, the mounting track  1308  had a locking lever  1312  that extends from the side of the mounting track  1308 . In one embodiment, the mounting track  1308  may include a set of contact plates that are designed to electrically connect the battery  1302  to the mounting track  1308  which is connected to both the motor assembly  106  and the throttle assembly  160  to deliver power to the motor assembly  106 . In an alternate embodiment, the battery  1302  may be directly connected to the motor assembly  106  and the throttle assembly  160  and electrically isolated from the mounting track  1308 .  
     [0070]FIG. 14 is a perspective view of the battery  1302  shown in FIG. 13 attached to the mounting track  1310 . In the embodiment shown in FIG. 14, the locking lever extends through the bore  1306  in the battery  1302  to retain the battery  1302  in position relative to the mounting track  1310 . Thus, in the embodiment shown in FIG. 14, to disengage the battery  1302  from the mounting track  1310 , the locking lever  1312  must be depressed. In alternate embodiments, various other mechanisms know in the art may be used to secure the battery  1302  to the mounting bracket  1310 .  
     [0071] With respect to each of the above two embodiments, the motor assembly and the battery are robustly, but removably secured to the scooter.  
     [0072] The foregoing description of embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to the practitioner skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.