Abstract:
A vehicle having two primary wheels and two or more retractable wheels that may be operated in either two-wheeled or multi-wheeled configuration with a sliding panel system for open or complete enclosure, with both the wheelprint and the open/enclosed panel system being quickly and independently operated.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention generally relates to a basic two-wheeled or multi-wheeled vehicle such as a motorscooter or motorcycle that is enclosable to protect riders and their cargo and has at least two additional, retractable wheels to add low-speed, stopping and cornering stability and a higher level of safety to the vehicle. This invention more specifically relates to a two-wheeled or multi-wheeled vehicle fitted with an enclosure to protect the rider or riders and their cargo from outside effects such as weather and road debris, and equipped with retractable stabilizing wheels to prevent the vehicle from becoming tipping over while cornering, being driven at slower speeds, and stopped. 
   2. Prior Art 
   There are a large number of two-wheeled vehicles, both engine powered such as motorcycles, motorscooters, and mopeds and human powered such as bicycles and rickshaws, available today. With the ever-present dichotomy of increasing petroleum prices and increasing urban density, as well as a human desire to travel the open roads, motorcycles and especially motorscooters and mopeds likely will increase in popularity as the vehicle of choice for personal, professional, business and military applications. While these vehicles have been available for many years, in light of this invention, they have several disadvantages. For example, traditional two-wheeled vehicles can be dangerous to operate, are open to inclement weather and injurious agents of all kinds, are irritatingly noisy to many, and are unsuitable for luggage, bags of groceries, laundry, packages and other commonly transported items. 
   One disadvantage of traditional two-wheeled vehicles is that they require a certain amount of dexterity and more skill for safe and convenient operation. For example, a rider who is not careful can cause the two-wheeled vehicle to tip over. Another related disadvantage is that a rider who does not stop correctly, for example by placing their leg outward too early or not at all to stabilize the stopped or slowing vehicle, could suffer excessive amounts of wear or an injury to his or her knees and joints, let alone damage the vehicle when it tips over. These disadvantages are magnified during stop and go traffic. Therefore, there is a need for a device or mechanism to help prevent a two-wheeled vehicle from tipping over as it slows or corners and when it is stopped. 
   Another disadvantage of traditional two-wheeled vehicles is that they typically are open to the air and provide the rider with very little protection against the outside environment. For example, these vehicles provide little or no protection from noise and exhaust pollution, from debris thrown up from the road, or from the weather. Moreover, such vehicles provide little or no protection in the event of an accident or from intentional harm, such as the throwing of rocks at or the discharge of a firearm toward the rider. Therefore, there is a need for a device or mechanism to help protect riders and their cargo from outside elements and interferences. 
   With all these disadvantages, the present invention is long overdue. There is a need for a vehicle that is safe to operate, whisper quiet, enclosable, and economical while at the same time takes up a minimal amount of road and parking space. There also is a need for a vehicle that can transport one or two persons and their cargo that is simple and convenient to get on and off, that is easy to park, and that is relatively noncomplex and aesthetically pleasing. For example, there is a great need for a vehicle that is adaptable to specific tasks such as for use as a personal transportation device, for use in the delivery of small packages for businesses, including a bullet-resistant enclosure for police and military use, and many other general and specialized functions. The unique vehicle disclosed in this specification satisfies these needs and more and is poised to become the next and greatest vehicle of choice to everyone. 
   BRIEF SUMMARY OF THE INVENTION 
   Two-wheeled vehicles such as motorcycles, motorscooters, mopeds, and bicycles require riders to use their feet to keep the vehicle upright when the vehicle slows down, comes to a stop, and sometimes when turning a corner slowly. If the vehicle is completely enclosed, the rider&#39;s feet cannot be so used, yet complete enclosure of the vehicle has many advantages. 
   To obtain these advantages, retractable wheels are provided for in this invention that will outstretch quickly whenever the rider wishes to deploy them. Additionally, a complete sliding panel enclosure system has been provided to quickly open and close window panels and door panels. Thus, a two-wheeled vehicle can be quickly converted to a multi-wheeled vehicle and vice versa. These conversions are independent of each other enhancing the vehicle&#39;s versatility and usefulness. 
   This invention allows a two-wheeled vehicle to be quickly converted to a multi-wheeled vehicle and vice versa and an open two-wheeled vehicle to be quickly converted to a completely enclosed vehicle and vice versa. The conversions are independent of each other, as the rider may elect. Additionally, the rider can opt to operate the vehicle with the retractable wheels in their extended position for added safety, especially when operation of the vehicle will be continuously at speeds slower than about 30 miles per hour (50 kph). Further, the enclosure helps prevent the rider from becoming and looking windswept and, especially with a safety/utility bar, may obviate the need for a helmet. 
   These improvements and other features of this invention will become readily apparent to those of ordinary skill in the art when the following detailed description of the preferred embodiments is read in conjunction with the accompanying drawings in which like reference numerals represent like components throughout the views. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a vehicle in accordance with this invention. 
       FIG. 2  is a side view of the vehicle shown in FIG.  1 . 
       FIG. 3  is a front view of the vehicle shown in FIG.  1 . 
       FIG. 4  is a rear view of the vehicle shown in FIG.  1 . 
       FIG. 5  is a top view of the vehicle shown in FIG.  1 . 
       FIG. 6  is a side view of the vehicle shown in  FIG. 2  illustrating a first exemplary retractable wheel assembly in the retracted position. 
       FIG. 7  is a side view of the vehicle shown in  FIG. 2  illustrating a first exemplary retractable wheel assembly in the extended position. 
       FIG. 8  is a side view of the vehicle shown in  FIG. 2  illustrating a second exemplary retractable wheel assembly in the retracted position. 
       FIG. 9  is a side view of the vehicle shown in  FIG. 2  illustrating a first exemplary means for entering and exiting the vehicle enclosure. 
       FIG. 10  is a side view of the vehicle shown in  FIG. 2  illustrating a second exemplary means for entering and exiting the vehicle enclosure. 
       FIG. 11  is a front view of an illustrative embodiment of a sliding panel system for entering and exiting the vehicle enclosure for use with this invention with the panels in a stored position. 
       FIG. 12  is a front view of the embodiment of the sliding panel system of  FIG. 11  with the panels in a stored position and the movable crossbar pivoted upwards to be horizontal. 
       FIG. 13  is a front view of the embodiment of the sliding panel system of  FIG. 11  with a first panel slid to the side and underneath the movable crossbar, exposing a second panel. 
       FIG. 14  is a front view of the embodiment of the sliding panel system of  FIG. 11  with the first panel slid to the side and underneath the movable crossbar, and a second panel slid upwards, exposing a third panel. 
       FIG. 15  is a front view of the embodiment of the sliding panel system of  FIG. 11  with the first panel slid to the side and underneath the movable crossbar, and the second panel slid across and above the movable crossbar. 
       FIG. 16  is a front view of the embodiment of the sliding panel system of  FIG. 11  with the first panel slid to the side and underneath the movable crossbar, the second panel slid up and then across and over the movable crossbar, and the third panel slid upwards, exposing a fourth panel. 
       FIG. 17  is a front view of the embodiment of the sliding panel system of  FIG. 11  with the first panel slid to the side and underneath the movable crossbar, the second panel slid up and then across and over the movable crossbar, and the third panel slid upwards to the top of the vertical bar. 
       FIGS. 18A-18C  are front views of several illustrative embodiments of extendable moveable crossbars, with  FIG. 18A  showing a telescoping configuration,  FIG. 18B  showing a first hinged configuration, and  FIG. 18C  showing a second hinged configuration. 
       FIG. 19  is a cross-sectional view of one embodiment of the frame of the sliding panel system of  FIG. 11  with two panels resting in the side of the frame. 
       FIG. 20  is a cross-sectional view of another embodiment of the frame of the sliding panel system of  FIG. 11  using rollers attached to the panels that roll within the interior of the frame. 
       FIGS. 21A-21C  are front views of several illustrative embodiments of locking mechanisms for the panels, with  FIG. 21A  showing a latch configuration,  FIG. 21B  showing a tab configuration, and  FIG. 21C  showing a hook configuration. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   This invention in its preferred form is a unique safe and comfortable two-wheeled vehicle with retractable wheels for stabilizing the vehicle at selective times and/or speeds and preventing the vehicle from tipping over when moving slowly, stopped or cornering and with an enclosure structure for enclosing and protecting riders and their belongings. The retractable wheels provide a means for stabilizing the vehicle at lower speeds, while stopped, and while cornering, if desired, and retract at normal operating speeds. The enclosure structure provides both safety for the riders and their belongings and protection from inclement weather and the road along with a unique variable opening means for entering and exiting the enclosure. 
   The basic two-wheeled vehicle can be of the type known in the art. As such, this invention can be a retrofit to an existing vehicle or can be built onto the vehicle at the time of manufacture as an original equipment option or accessory. Motorscooters and motorcycles, mopeds and motorized bicycles, and conventional bicycles can benefit from this invention. For example, the basic vehicle assembly of this invention can include a frame, a drive wheel or driving device, and a steering assembly including a handlebar, a fork, a head tube and the front wheel. A preferred embodiment of this invention comprises this basic vehicle assembly, one or more retractable wheels and the enclosure assembly. 
   A retractable wheel preferably is located on each side of the vehicle typically proximal to the rear axle of the vehicle, where they can provide a greater combination of safety and convenient placement so as to prevent the vehicle from tipping when extended, yet not adversely impair the operation of the vehicle or the movement of the rider. The retractable wheels reversibly move from an upper retracted position distal from the road to a lower extended position proximal to the road and when retracted can be located inside of or outside of the enclosure structure depending on the enclosure structure selected. The retractable wheels can be operated either manually or automatically and can be designed to extend to prevent the vehicle from tipping at slower speeds, while stopped or while cornering, and to retract when less necessary at higher speeds. 
   The enclosure generally is a rigid outer casing that is positioned around the riding area of the vehicle. The enclosure is mounted securely on the main frame of the vehicle. The front steering wheel and the rear driving wheel of the typical vehicle remain exposed by extending outwardly of the enclosure. The enclosure includes windows and a means for entering and exiting the enclosure, each of which preferably can be opened and closed in varying arrays. The enclosure can include safety devices such as roll bars, safety bars, utility bars, and safety belts, and convenience and luxury options such as headlights and window wipers, storage bins or compartments, audio/video systems, climate control systems, and the like. 
   The base vehicle of this invention can be any conventional two-wheeled vehicle, and preferably a powered vehicle such as a motorscooter, motorcycle, moped, or motorized bicycle. For ease of disclosure herein, the following description of the preferred embodiments and the figures will use a motorscooter as an exemplary embodiment. However, it should be kept in mind that a motorscooter is simply an exemplary embodiment and the invention is not limited to motorscooters. Thus, as used herein, the term two-wheeled vehicle refers to any vehicle that has at least two wheels on the road surface at all times in a normal operating mode. 
   Enclosure 
   Referring to  FIGS. 1 and 2 , an exemplary vehicle  10  generally comprises the typical components of a two-wheeled vehicle, such as frame  12 , front wheel  14 , rear wheel  16 , handlebar and steering assembly  18 , brake and gas input/accelerator controls (not shown), foot rests or floor  20 , and seat  22 . To this vehicle  10 , a retractable wheels  50  and enclosure  70  are added according to preferred embodiments of the invention. Both retractable wheels  50  and enclosure  70  are attached to vehicle  10  at appropriate positions on frame  12 . As will become evident herein, the actual attachment means and mechanisms are within the skill level of those of ordinary skill in the art, and various means and mechanisms for attaching and activating (a motor  60  as shown in  FIG. 1 , and a pull handle  66  as shown in  FIG. 2 ) retractable wheels  50  and attaching enclosure  70  to vehicle  10  are contemplated and are not limited to the illustrative embodiments that may be disclosed herein or shown in the figures. 
   Referring to  FIGS. 1-5 , enclosure  70  is mounted upon frame  12  of vehicle  10  and provides a surrounding structure that protects rider R and cargo from varying elements such as the weather, road debris, noise, the environment, and/or intentionally or unintentionally aimed projectiles or other items. Further, enclosure  70  can have a headlight  72  (as shown in  FIGS. 1 and 2 ) or allow for a headlight  72  on the base vehicle  10  to shine or protrude through enclosure  70  (as shown in FIG.  3 ), windows, one or more of which can be openable, and windshield wiper  74 . Preferably, enclosure  70  has front window or windshield  92 , side windows  94 , and back window  96 . Therefore, rider R can see through enclosure  70 . Further, enclosure  70  can have a means for entering and exiting  110  enclosure  70 , such as shown in  FIGS. 9-21  and described in more detail below. 
   In more detail, enclosure  70  generally comprises a front wall  80 , two side walls  82 , a rear wall  84  and a top wall or roof  86  interconnected into a preferably unitary whole structure. The various walls  80 ,  82 ,  84 ,  86  and other components of enclosure  70  can be connected together using any technique, including but not limited to conventional techniques such as welding, fasteners and adhesives. It is preferable that the various walls  80 ,  82 ,  84 ,  86  and other components of enclosure  70  be connected together securely to minimize the possibility of separation. Various additional safety features such as support ribs, roll bars, safety bars, utility bars, airbags, and the like can be added as desired. 
   Enclosure  70  may be affixed to frame  12  using any conventional attachment means such as welding, fasteners and adhesives. For example, lower edges of side walls  82  and possibly lower edges of front wall  80  and/or lower edges of rear wall  84  can be attached to a suitable portion of frame  12 . Alternatively, additions or extensions can be attached to frame  12  to assist in attaching enclosure  70  to frame  12 , or in supporting enclosure  70  on frame  12 . For example, a plurality of ribs (not shown) may be secured to frame  12  and the various walls  80 ,  82 ,  84 ,  86  may be secured to the ribs. Ribs, in an illustrative embodiment, can be attached at a lower end to frame  12  and extend outwardly generally horizontally and then curve upwardly generally vertically and then optionally curve inwardly generally horizontally terminating at an upper end. Side walls  82  thus can be attached to the vertical sections of ribs (with a portion of side walls  82  curving inwardly to be attached to the lower horizontal portions of ribs). Front wall  80  and rear wall  84  can be attached to other ribs or directly to side walls  82 . Top wall  86  can be attached to the upper horizontal sections of ribs or directly to side walls  82 . 
   Referring to  FIG. 3 , front wall  80  acts as the lead wall of vehicle  10 . As can be seen, front wall  80  preferably is configured to cooperate with and not to interfere with the operation of front wheel  14  and steering assembly  18 . Further, front wall  80  can be configured to comprise a windshield  92 , a windshield wiper  74 , a headlight  72 , and turn signals  76 . In the embodiment shown in  FIG. 3 , windshield  92  extends downward a distance sufficient for headlight  72  of base vehicle  10  to shine through, obviating the need for a headlight on front wall  80  itself. 
   Referring to  FIG. 4 , rear wall  84  acts as the trailing wall of vehicle  10 . As can be seen, rear wall  84  preferably is configured to cooperate with and not to interfere with the operation of rear wheel  16 , engine  200  and drive train  202 , and, as discussed in more detail below, retractable wheels  50 . Further, rear wall  84  can be configured to have a hingedly engaging door  88  with a handle attached thereto allowing selective access to the interior of the enclosure  70 . Additionally, rear wall  84  can be configured to have turn signals  75 , brake lights  77  and license plate assembly  79 . 
   Referring to  FIG. 5 , top wall  86  acts as the roof or ceiling of vehicle  10 . As can be seen, top wall  86  covers the entire enclosure  70  from front wall  80  to rear wall  84  and across between side walls  82 . Further, top wall  86  can be configured to have a sunroof or moonroof (not shown), or to be a solid opaque, translucent or transparent (or combinations thereof) wall. 
   The materials of manufacture of enclosure  70  are dependent on the style and type of enclosure  70  necessary or desired, as well as on the level of safety and comfort, accessories, and equipment desired by the rider R. One of ordinary skill can determine the appropriate materials of manufacture of enclosure  70  without undue experimentation. Preferably, enclosure  70  is strong enough to withstand winds and other more aggressive environmental conditions. Canvas, metals, woods, and plastics and glasses, as well as more exotic materials such as carbon and graphite fiber based materials are suitable. Glass, clear plastics and polymers, and other transparent materials are suitable for windows  92 ,  94 ,  96 . As will be readily apparent to those skilled in the art, however, the materials of manufacture of the various components of enclosure  70  can be varied without departing from the spirit and scope of the invention. Furthermore, the above described enclosure  70  is not to be limited to the exact details of construction enumerated above. 
   It is further contemplated that vehicle  10  can have the comforts, accessories, equipment, and other optional components of conventional vehicles. For examples, enclosure  70  can have visors, communications systems, audio systems, video systems, climate control systems, and mirrors. Further, due to the nature of enclosure  70 , various storage compartments and areas can be made available, such as storage box  71  shown in FIG.  2 . 
   Enclosure  70  preferably is manufactured or mounted upon frame  12  so that enclosure  70  is relatively well balanced upon frame  12 . Obviously, if enclosure  70  is positioned off-balance on frame  12 , the entire vehicle  10  may lean to one side, which can be dangerous and possibly reduce gas mileage. Importantly, if enclosure  70  is positioned off-balance, there may be a greater likelihood that vehicle  10  with enclosure  70  may tip to one or the other side, or tip over. 
   As is apparent, enclosure  70  must not interfere with either the steering or driving of vehicle  10 . As such, enclosure  70  can be manufactured and mounted so as to allow the free movement of front wheel  14  and steering mechanism  18  of vehicle  10 , and so as to allow the free operation of rear wheel  16  and drive components  202  of vehicle  10 . Further, if retractable wheels  50  are included, enclosure  70  must allow free operation of retractable wheels  50 . The actual final structural design of enclosure, in light of this disclosure, is within the skill level of an ordinary automotive designer. 
   Retractable Wheels 
   Referring to  FIGS. 6-8 , while enclosure  70  provides protection to rider R, retractable wheels  50  add stability to vehicle  10  by, when extended, preventing vehicle  10  from tipping over. Because a preferred vehicle  10  has two wheels  14 ,  16  along a center axis CL, vehicle  10  is less stable in the direction normal to center axis CL and can tip over without the additional support provided by retractable wheels  50 , particularly when stopped, traveling at slower speeds, or cornering. While retractable wheels  50  may be located at many places along the side of vehicle  10 , retractable wheels  50  are preferably proximal to the rear of vehicle  10  because such an arrangement minimizes interference with the front wheel  14  steering assembly  18  in controlling the direction of vehicle  10  and with the legs of the rider R. 
   Retractable wheels  50  can be constructed to be retractable by an automatic system such as motor  60  as exemplified in  FIG. 1  or a manual system such as pull handle  66  as exemplified in FIG.  2 . If an automatic system is used, retractable wheels  50  preferably are retracted when vehicle  10  is moving, or moving above a preset speed. For example, retractable wheels  50  can automatically retract when vehicle  10  is moving faster than 25 miles per hour (40 kph). Preferably, retractable wheels  50  automatically retract when vehicle  10  is moving faster than 15 miles per hour (24 kph). Even more preferably, retractable wheels  50  automatically retract when vehicle  10  is moving faster than 7-10 miles an hour (11-16 kph). One of ordinary skill in the art can select speeds at or above which retractable wheels  50  will automatically retract. 
   Referring to  FIGS. 6 and 7 , an illustrative example of an automatic, or motorized, extension and retraction system contemplated by this invention is shown. Referring to  FIG. 8 , an illustrative example of a manual, or hand actuated, extension and retraction system contemplated by this invention is shown.  FIGS. 6 and 7  illustrate vehicle  10  equipped with automatically retractable wheels  50  as one illustrative embodiment of this invention. More particularly, vehicle  10  has retractable wheels  50  illustrated in the down or extended position in FIG.  6  and in the up or retracted position in FIG.  7 . 
   Referring to  FIGS. 6 and 7 , retractable wheel  50  is operationally attached to frame  12  via leg assembly  52 . For purposes of this specification, only one leg assembly  52  will be discussed as the leg assemblies  52  for each side of vehicle  10  are substantially similar or identical, and may be possibly mirror images of each other, and the same component reference numbers will be utilized. Leg assembly  52  preferably comprises strut  54 , attached at its proximal end to vehicle  10  at pivot point  56 . Axle  58  is located at the distal end of strut  54  and is associated with a retractable wheel  50 . 
   It is understood that the retractable wheel  50  may be replaced by a ski, float, or other ground contact member depending on the environment in which vehicle  10  is to be operated. Further, retractable wheel  50  and any other such ground contact member can be replaceable and interchangeable. One such ground contact member can be a rigid or semi-rigid material or composite such as a pole vault pole. In a manner similar to the retractable wheel  50 , the ski, float, pole or other ground contact member can be extended and retracted. 
   Pivot point  56  either can be an attachment point on frame  12  or another part of vehicle  10  or can be a drive shaft of an actuating motor  60  for extending and retracting retractable wheel  50 . If pivot point  56  is an attachment point on frame  12 , leg assembly can further comprise control arm  55  attached to strut  54  and extending to an actuating motor  60  located strategically on vehicle  10  or within enclosure  70 . When actuating motor  60  is activated to extend retractable wheel  50 , actuating motor  60  pivots or otherwise moves control arm  55  in a direction, generally downward, thus moving retractable wheel  50  downward into the extended position shown in FIG.  6 . When actuating motor  60  is activated to retract retractable wheel  50 , actuating motor  60  pivots or otherwise moves control arm  55  in a direction, generally upward, thus moving retractable wheel  50  upward into the retracted position shown in FIG.  7 . Actuating motor  60  can comprise an internal or external locking means (not shown) to hold retractable wheel  50  in either or both of the extended and retracted positions. Other locking means, mechanical or otherwise, also can be incorporated without undue experimentation. 
   Alternatively, if pivot point  56  is the drive shaft of actuating motor  60 , control arm  55  can be unnecessary. When actuating motor  60  is activated to extend retractable wheel  50 , actuating motor  60  pivots or otherwise rotates strut  54  in a direction, generally downward, thus moving retractable wheel  50  downward into the extended position shown in FIG.  6 . When actuating motor  60  is activated to retract retractable wheel  50 , actuating motor  60  pivots or otherwise rotates strut  54  in a direction, generally upward, thus moving retractable wheel  50  upward into the retracted position shown in FIG.  7 . Actuating motor  60  can comprise a locking means as disclosed above to hold retractable wheel  50  in either or both of the extended and retracted positions. Other locking means, mechanical or otherwise, also can be incorporated without undue experimentation. 
   Control arm  55  can be paired with or replaced by a tension spring (not shown). Tension spring can be used to dampen the movement of strut  54 , to help rotate strut  54 , and/or to help maintain strut  54  in a desired position (retractable wheels  50  extended or retracted), depending on the placement of tension spring (not shown). Tension spring also can be use to retract retractable wheel  50  when actuating motor  60  is deactivated, thus eliminating the need for a reversible actuating motor  60 . 
   Referring to  FIG. 8 , vehicle  10  is shown equipped with manually retractable wheels  50  as another illustrative embodiment of this invention, with retractable wheels  50  illustrated in the down or extended position.  FIG. 2  shows vehicle  10  equipped with manually retractable wheels  50  in the up or retracted position. In this embodiment, control arm  55  terminates in a handle  57  on the end opposite the connection to strut  54 . Handle  57  is proximal to rider R such that rider R can pull handle  57  upwards to retract retractable wheels  50  and push handle  57  downwards to extend retractable wheels  50 . Control arm  55  can comprise a locking means to hold retractable wheel  50  in either or both of the extended and retracted positions. Other locking means, mechanical or otherwise, also can be incorporated without undue experimentation. A tension spring (not shown) also can be used with a manual retraction system to dampen the movement of strut  54 , to help rotate strut  54 , and/or to help maintain strut  54  in a desired position (retractable wheels  50  extended or retracted), depending on the placement of tension spring (not shown). 
   When fully extended, the lowest part of each retractable wheel  50  is coplanar with or above a plane comprising the lowest part of front wheel  14  and the lowest part of rear wheel  16  (wheel being defined as including both the rim and the tire, if both are present). In most cases, the plane comprising the lowest part of front wheel  14  and the lowest part of rear wheel  16  is the road surface. Thus, when extended, retractable wheels  50  either touch the road surface such that vehicle  10  has four wheels touching the road surface, or are above the road surface such that a tipping of vehicle  10  from the vertical or upright position will cause one of retractable wheels  50  to touch the road surface. 
   Retractable wheels  50  allow rider R to control the lean of vehicle  10  into and out of turns. That is, retractable wheels  50 , when extended, may contact the ground when vehicle  10  is leaned into a curve. This small amount of contact makes vehicle  10  more easily ridden for persons that may not have a good sense of balance and makes vehicle  10  more easily handled by rider R. Retractable wheels  50  are positioned on frame  12  so that they do not affect the function of either front wheel  14  or rear wheel  18  when turning vehicle  10 . 
   Systems for automatically extending and retracting retractable wheels  50  are within the knowledge of those skilled in the art. As a first basic example, such a system can comprise a reversible motor  60  mounted on frame  12  with an on/off or up/down switch (not shown) located on handlebar and steering assembly  18  and electrically connected to motor  60 . Motor  60  can be powered by vehicle  10 &#39;s battery (not shown) or alternator (not shown). When rider R wishes to extend retractable wheels, rider R presses the switch, thus activating motor  60 , which extends retractable wheels  50 . To retract retractable wheels  50 , rider R can release switch, or move switch to a different position, depending on the type of switch. 
   Another basic example of a system for automatically extending and retracting retractable wheels  50  also can comprise a reversible motor  60  mounted on frame  12 , but this time with an automatic switch (not shown) connected to vehicle  10 &#39;s speedometer and electrically connected to motor  60 . As above, motor  60  can be powered by vehicle  10 &#39;s battery (not shown) or alternator (not shown). When vehicle  10  decelerates to below a predetermined speed, automatic switch is activated by speedometer, thus activating motor  60  in an extension direction, which extends retractable wheels  50 . When vehicle  10  accelerates to above the predetermined speed, automatic switch either is activated by speedometer to reverse motor  60  to a retraction direction, thus retracting retractable wheels  50 , or automatic switch is deactivated by speedometer, thus deactivating motor  60 , allowing tension spring to retract retractable wheels  50 . 
   Retractable wheels  50  also can function as a kickstand when extended and as an added safety device when retracted. In a kickstand example, when retractable wheels  50  are extended, vehicle  10  can be supported by them in a parked position, thus mimicking and eliminating the need for a separate kickstand. When retractable wheels  50  are extended, this embodiment of vehicle  10  will remain generally upright so that vehicle  10  is safer to use and ride and to slow down, stop at traffic signals, and park. Further, as vehicle  10  stands upright, rider R can ingress or egress from the enclosure  70  more easily, and can park vehicle  10  more easily. In an added safety device example, when retractable wheels  50  are retracted, they can act as side bumpers or protection from side impact. 
   Retractable wheels  50  are extremely useful, multi-functional, unique additions to a vehicle, making a vehicle safer, more convenient, and more desirable. 
   Sliding Panel System 
   Referring to  FIGS. 9 and 10 , enclosure  70  includes a means for entering and exiting enclosure  70 .  FIG. 9  shows the means for entering and exiting enclosure  70  as a simple flexible panel P.  FIG. 10  shows the means for entering and exiting enclosure  70  as a system of preferably rigid sliding panels  114 . 
   Referring to  FIGS. 11-17 , an illustrative sliding panel system utilized as a means for entering and exiting enclosure  70  comprises frame  112  containing a plurality of sliding panels  114 . Frame  112  and panels  114  in combination generally constitutes a single sliding panel unit  110  that can be installed or retrofitted in an appropriate location on enclosure  70 . Panels  114  slide along horizontal and vertical axes within frame  112  so that placement of panels  114  can close frame  112  entirely, or create openings of different sizes, shapes and locations within frame  112 . As shown in  FIG. 11 , one embodiment of sliding panel unit  110  comprises frame  112 , panels  114 , vertical crossbar  116 , horizontal crossbar  118 , and moveable crossbar  120 . 
   For illustrative purposes throughout  FIGS. 11-17 , the sliding panel system comprises rectangular frame  112 , vertical crossbar  116 , horizontal crossbar  118 , moveable crossbar  120 , and a plurality of panels  114 . Frame  112  in this illustrative embodiment is a relatively lightweight and strong quadrilateral with opposite sides parallel and equal in length. Vertical crossbar  116  extends from top side  112 A center of frame  112  to bottom side  112 B center of frame  112 . Horizontal crossbar  118  extends from the center of first side  112 C of frame  112  to the center of vertical crossbar  116 . Moveable crossbar  120  is attached to the center of vertical crossbar  116  or the center of second side  112 D of frame  112  by pivoting device  122  or hinge so that it can be folded downwards or upwards vertically proximal to vertical crossbar  116  or second side  112 D of frame  112  or pivoted to be horizontal preferably spanning the distance between vertical crossbar  116  and second side  112 D of frame  112 . Panels  114  can be stored in one corner of frame  112  and moved to different parts within frame  112  when in use. Frame  112 , vertical crossbar  116 , horizontal crossbar  118 , and moveable crossbar  120  can be made from any appropriate structural materials, currently known or developed in the future, such as wood; plastic and other polymers; aluminum, steel, titanium and other metals; fibreglasses, graphite and carbon composites, and other composites; or any relatively lightweight, relatively strong, stable material. 
     FIG. 11  illustrates that frame  112  can be structured so as to contain and retain panels  114 .  FIG. 11  illustrates panels  114  in a stored position in the lower right quadrant, wherein the remaining three-quarters of the area in frame  112  is open, namely, the lower left, upper right and upper left quadrants. This allows a passenger or driver to enter and exit the vehicle through the left half of frame  112 . 
   Panels  114  also can be quadrilaterals with opposite sides parallel and equal. Panel  114  length preferably is equal to or slightly less than approximately half the length of frame  112 , and panel  114  width preferably is equal to or slightly less than approximately half the width of frame  112  so that, at all times, each panel  114  will sit securely yet slidably between frame  112  and the appropriate set of crossbars  116 ,  118 ,  120 . The thickness, or depth, of each panel  114  is dependent on the materials of manufacture and the purpose of panel  114 , as discussed in more detail below, but preferably is less than the total depth of frame  112 . Panels  114  can be made from materials such as woods; plastic and other polymers; aluminum, steel, titanium and other metals; transparent, translucent, colored and opaque glasses; wire screens; insulative, shatter resistant, bullet proof or other specialty materials; or any other suitable material, or a combination of two or more of the above. For example, in one embodiment, two panels  114  can be made of aluminum, one panel  114  can be made of glass, and one panel  114  can be made of half glass and half aluminum. 
   Vertical crossbar  116  extends from top side  112 A of frame  112  to bottom side  112 B of frame  112 . Vertical crossbar  116  preferably is centered generally between first side  112 C of frame  112  and second side  112 D of frame  112  so that one or more panels  114  can be placed on each side of vertical crossbar  116 . The width of vertical crossbar  116  can be thicker or thinner than the width of the walls of frame  112 . Vertical crossbar  116  can have a flat, rectangular cross-section and function more of a brace. Alternatively, vertical crossbar  116  can have a shaped cross-section and be used, for example, as a guide for rollers attached to panels  114 , as discussed in more detail below. 
   Horizontal crossbar  118  extends from first side  112 C of frame  112  to vertical crossbar  116  so that its length generally is approximately one-half the horizontal length of frame  112 . Horizontal crossbar  118  preferably is centered generally between top side  112 A of frame  112  and bottom side  112 B of frame  112  so that panel  114  can be placed above and below horizontal crossbar  118 . The width of horizontal crossbar  118  also can be thicker or thinner than the width of the walls of frame  112 . Horizontal crossbar  118  also can have has a flat, rectangular cross-section and function more of a brace. Alternatively, horizontal crossbar  118  also can have a shaped cross-section and be used, for example, as a guide for rollers attached to panels  114 , as discussed in more detail below. 
   Vertical crossbar  116  and horizontal crossbar  118  are added to support the structure of frame  112  and to block the cracks between panels  114  when panels  114  are in the closed position. If vertical crossbar  116  and horizontal crossbar  118  are used as braces only, the thickness of vertical crossbar  116  and horizontal crossbar  118  preferably does not extend into the inner portion of frame  112 . Thus, such fixed crossbars  116 ,  118  are not contained within the sliding panel area of frame  112 , rather they are attached to frame  112  so that panels  114  slide either in front of or behind flat crossbars  116 ,  118 . Alternatively, if vertical crossbar  116  and horizontal crossbar  118  are used as guides for guiding and holding panels  114  in place, crossbars  116 ,  118  have a formed cross-section allowing a guiding portion of panels  114 , such as roller or pads, to fit within the cross-section of crossbars  116 ,  118 , as shown illustratively in FIG.  20 . 
   Moveable crossbar  120  can be attached to vertical crossbar  116  by pivoting device  122  or hinge so that moveable crossbar  120  can be folded downwards or upwards vertically or pivoted to be horizontal. When moveable crossbar  120  is in its downward or upward vertical position, moveable crossbar  120  generally is parallel to and proximal or touching vertical crossbar  116 . In this position, as shown illustratively in  FIG. 11 , there is provided an opening in half of the area of frame  112 , specifically the left side of frame  112 . This allows a passenger or driver to enter and exit the vehicle. 
   Pivoting moveable crossbar  120  to be horizontal helps close the panel system. Moveable crossbar  120  is pivoted to the horizontal position, in which position the end of moveable crossbar  120  distal from the pivoting device  122  and vertical crossbar  116  is now proximal to second side  112 D of frame  112 . Moveable crossbar  120  can be locked in place against second side  112 D of frame  112  using any known or future developed locking means, such as latches, pins, clips, sliding bars, and the like. Once moveable crossbar  120  is in place against or proximal to second side  112 D of frame  112 , moveable crossbar  120  supports panel  114  that has been slid over moveable crossbar  120 , as shown in more detail in  FIGS. 15 and 16 . Further, moveable crossbar  120  can be structured to block cracks between panel  114  and moveable crossbar  120  when the panel system is in the closed and semi-closed positions. 
     FIG. 11  illustrates moveable crossbar  120  in a folded down vertical position lying adjacent to the lower half of vertical crossbar  116 . In  FIG. 12 , moveable crossbar  120  is being pivoted upwards to be horizontal. In  FIG. 13 , moveable crossbar  120  is in the horizontal position and is adjacent to left side  112 D of frame  112 , which is the operating position for supporting panel  114 . Moveable crossbar  120  generally is attached to the middle of vertical crossbar  116  so that the point of attachment is on the same linear plane with horizontal crossbar  118  and so that the point of attachment is in the center of frame  112 . The width of moveable crossbar  120  also can be thicker or thinner than the width of the walls of frame  112 . Moveable crossbar  120  also can have a flat, rectangular cross-section and function more of a brace. However, as moveable crossbar  120  generally supports one or more panel  114 , moveable crossbar  120  also can have a shaped cross-section and be used, for example, as a guide for rollers attached to the panels  114 . More specifically, moveable crossbar  120  have a formed cross-section allowing a guiding portion of panels  114 , such as roller or pads, to fit within the cross-section of crossbars  116 ,  118 , as shown illustratively in FIG.  20 . 
   Referring now to  FIGS. 12-17 , the operation of sliding panel unit  110  is shown in greater detail. With panels  114  in a stored position, at least a portion of the internal area of frame  112  is open. For example, when panels  114  in a four-panel configuration are in the stored position in a corner of frame  112 , three-quarters of the area of frame  112  is open. This opening allows a passenger or driver to enter and exit vehicle  10 . 
     FIG. 11  illustrates an embodiment of sliding panel unit  110  in the open position. To close sliding panel system  110 , moveable crossbar  120  is pivoted upward or downward, as appropriate, to be horizontal and extend between vertical crossbar  116  and second side  112 D of frame  112 . A single panel  114 A, previously stored in a corner of frame  112 , can be slid from the stored position and underneath moveable crossbar  120 . This closes the bottom half of frame  112  while leaving the top half open. Another single panel  114 B can be slid upwards from the stored position and locked into place. This closes three-quarters of frame  112  while leaving one top quadrant open. This same panel  114 B can be slid across and over moveable crossbar  120 . In this position, one top quadrant of frame  112  is left open and the remaining three quadrants are closed. Another single panel  114 C from the stored position can be slid upwards and locked into place, thus closing entire frame  112 . The remaining panel  114 D in the stored position remains there, and can be permanently mounted so that it is not slidable, or it can be made slidable so that more configurations can be created. 
     FIG. 12  illustrates the initial moving of moveable crossbar  120  towards the horizontal position. Panels  114  are capable of displacement between an open position where panels  114  are contained in one corner of frame  112 , and a closed position where panels  114  are moved aside with respect to the open position. Variations of closed and open positions can be formed depending on where panels  114  are contained within frame  112 . 
     FIG. 13  illustrates the process of sliding panel  114 A to the side, underneath moveable crossbar  120 , where it will come into contact with second side  112 D of frame  112 . Now moveable crossbar  120  also can be laterally supported by the upper horizontal edge of panel  114 A, as well as, or alternatively, being locked into place by latches, pins, bolts or the like, or both. In this position, the top half of frame  112  is open and the bottom half is closed. Specifically, in this position, the top left quadrant of frame  112  is open and the remaining three quadrants are closed. Panels  114  pass from one to the other of these various positions by lateral and longitudinal displacement in a direction from the closed plane to the opening plane and sliding in the opening plane. 
     FIG. 14  illustrates the process of sliding panel  114 B, which was behind panel  114 A in this illustrative embodiment, upwards between vertical crossbar  116  and first side  112 C of frame  112 . Panel  114 B can be left in this position, that is, in the upper right of frame  112 , by locking panel  114 B within frame  112  by the means disclosed below. In this position, the top half of the panel system frame  112  is half closed and the bottom half is closed. Horizontal crossbar  118  does not necessarily laterally support panel  114 B, as panel  114 B can be slid in front of or behind flat horizontal crossbar  118 . Alternatively, horizontal crossbar  118  can have a structure allowing it to support the bottom edge of panel  114 B when panel  114 B is in the upper position. 
     FIG. 15  illustrates the process of sliding panel  114 B laterally over movable crossbar  120 , where it will come into contact with second side  112 D of frame  112 . Now moveable crossbar  120  also can support panel  114 B. In this position, the top half of the panel system frame  112  is half closed and the bottom half is closed. Specifically, in this position, the top right quadrant of frame  112  is open and the remaining three quadrants are closed. 
     FIG. 16  illustrates the process of sliding panel  114 C, which was behind panel  114 A in this illustrative embodiment, upwards between vertical crossbar  116  and first side  112 C of frame  112 . Panel  114 C now can be left in this position, that is, in the upper right of frame  112 , by locking panel  114 C within frame  112  by the means already disclosed. 
     FIG. 17  illustrates the top half of panel system frame  112  closed and the bottom half closed, after panel  114 C has been slid. Panel  114 D can be permanently mounted so that it is not slidable, or panel  114 D can be made slidable so that more configurations can be created. 
     FIGS. 18A-18C  illustrate that the length of moveable crossbar  120  can be extendable or telescoping or foldable so that moveable crossbar  120  can make contact with second side  112 D of frame  112 . 
     FIG. 19  illustrates that panels  114  can sit in direct contact with the frame  112  and its adjacent crossbar  116 ,  118 ,  120 , and be separated form each other by separating wall  126 . 
     FIG. 20  illustrates an alternative embodiment in which panels  14  can be placed on a guidance device  124 , such as wheels, rollers or pads, so that they slide along the inner walls of the frame  112  and crossbars  116 ,  118 ,  120 . Guidance device  124  can be placed on one, two, three, or all four sides of each panel  114 . Conversely, guidance device  124  can be placed along the inner walls of frame  112  and/or along the sides of crossbars  116 ,  118 ,  120 . Such guidance devices  124  and structures are known in the art, and can be similar to the common sliding glass shower door rail structure, the sliding glass patio door rail structure, and/or the folding closet door hanging structure. Some illustrative guidance devices  124  also include lower friction slides, such as nylon glides. Such guidance devices  124  dispose each panel  114  in such a way that the panel  114  is located slightly raised or removed from frame  112  or crossbars  116 ,  118 ,  120 , so that panel  114  is no longer in direct contact with frame  112  or its adjacent crossbar  116 ,  118 ,  120 . Panels  114  can be slid manually or be displaced by means of an electric motor (not shown). 
   Further, weather stripping, insulation and/or other sealants can be placed along the inner edges of frame  112  and/or along the sides of crossbars  116 ,  118 ,  120 . For use as a door to help enclose vehicle  10 , thin strips of rubber, plastic or felt lining frame  112  and crossbars  116 ,  118 ,  120  can exclude rain, snow and/or cold air. Sealants to prevent outside air, which may be contaminated or otherwise undesirable, from entering vehicle  10  also may be placed along the inner edges of frame  112  and/or along the sides of crossbars  116 ,  118 ,  120 . 
     FIGS. 21A-21C  illustrate example locking devices, such as latches  180 , pins  182 , hooks  184 , bolts or the like, that can be attached to panels  114  to hold panels  114  into place if need be. Locking devices can also be placed on the inner edges of frame  112  and/or on the sides of crossbars  116 ,  118 ,  120 . Such locking devices are known and can be similar to those currently use on sliding windows and screens in residences. Otherwise, panels  114  can be held in place by friction or the surrounding structures. 
   In addition to closure by lateral and longitudinal displacement of panels  114 , various configurations can also be made by using different materials as panels  114 . For example, in one embodiment, panels  114 A,  114 D can be aluminum, and panels  114 B,  114 C can be glass or wire screen. In this embodiment, the bottom half of closed panel system  110  is solid and opaque and the top half of closed panel system  110  is translucent or permeable. For use on vehicle  10 , it is preferable that at least panel  114 B is a window. Panels  114 A and  114 C also can be windows, as well as panel  114 D. Additionally, in several other illustrative embodiments, panels  114  can be insulative or non-insulative, shatterproof or break and crack resistant, or bulletproof. 
   Sliding panel unit  110  allows multiple panels  114  to slide along both the horizontal and vertical axes of the frame  112 . Such a multi-directional displacement can create openings of different sizes, shapes and locations within frame  112 . Panels  114  can take up little space but can be rigid enough when closed to withstand high winds and other weather elements. Panels  114  are conveniently contained within frame  112  so there are no loose pieces to be lost or destroyed. Further, panels  114  do not have to swing out to open, saving space and making them easy to deal with. Because panels  114  do not swing out to open, they are not subject to the wind and can be left open to drive vehicle  10 . 
   The above detailed description of the preferred embodiments, illustrative examples of structures and materials, and the appended figures are for illustrative purposes only and are not intended to limit the scope and spirit of the invention, and its equivalents, as defined by the appended claims. While the invention is described herein in conjunction with these illustrative embodiments, it will be understood that the invention is not limited to these embodiments. One skilled in the art will recognize that many variations can be made to the invention disclosed in this specification without departing from the scope and spirit of the invention.