Abstract:
A water shield structure for a transportation device and the transportation device having such a water shield structure. The transportation device is preferably a self-balancing device and may include a friction drive motor. The water shield structure helps reduce the entry of moisture from a riding surface into the wheel envelope or drive mechanism of the device. The water shield structure may extend laterally from a wheel and be enclosed, at least in part, in a housing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of earlier filed U.S. provisional application No. 62/241,050, filed Oct. 13, 2015, entitled Water Wheel Guard for Preventing Friction Drive Slippage by the inventor herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to inhibiting moisture penetration, particularly from rain water, into a wheel envelope and, more specifically, to inhibiting moisture penetration into the drive mechanism of a vehicle propelled with a friction based drive. 
       BACKGROUND OF THE INVENTION 
       [0003]    The prior are includes self-balancing, single wheel structure vehicles. One example is the Solowheel, described in U.S. Pat. No. 8,807,250 issued to Chen (the inventor herein) on Aug. 19, 2014, and entitled Powered Single-Wheel Self-Balancing Vehicle for Standing User. Another example is the device of Simeray, described in U.S. Pat. No. 8,616,313, issued on Dec. 31, 2013, and entitled Motorized Transport Vehicle for a Pedestrian. 
         [0004]    These prior art devices illustrate the use of drive motors and related components that may be disadvantageously heavy, power consumptive (requiring more and heavier batteries) and/or bulky. 
         [0005]    With respect to overall device weight, it is desirable to have a lightweight device. This would permit a user to readily stow or carry the device. Consider, for example, a user who might use the device to get to a bus stop, stow the device during the bus ride and then remount the device upon descending the device. This on again-off again, stow and unstow routine could be repeated for other errands or destinations through the day. It is important in this instance that the device is sufficiently lightweight to be readily carried or stowed, for example, in a backpack or the like. 
         [0006]    With respect to drive systems, small, lightweight and higher efficiency friction drive motors are known in the art. One embodiment of a friction drive motor is shown in  FIG. 3  herein and others are shown in U.S. patent application Ser. No. 14/811,702, filed Jul. 28, 2015, by Chen, and entitled Fore-Aft Self-Balancing Transportation Device with Low and Centered Foot Platform, which is hereby incorporated by reference as though disclosed in its entirety herein. These devices include the positioning of a drive head onto the interior surface of the rim. When it is raining or other moisture is present, the contact surface of the rim may become wet causing the drive head to “slip” on the rim contact surface, thereby reducing the ability of the device to perform fore-aft self-balancing and diminishing user control of the device. 
         [0007]    Thus, a need exists to inhibit moisture penetration into the wheel envelope or onto the drive head or drive surface of a personal transportation device so that lightweight and more energy efficient friction drive motors may be used in these devices. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, it is an object of the present invention to a more lightweight and easily portable personal transportation device. 
         [0009]    It is another object of the present invention to provide a water guard arrangement for friction-drive propelled vehicles of any type. 
         [0010]    It is also an object of the present invention to provide a water guard arrangement for a personal transportation device having a friction drive. 
         [0011]    These and related objects of the present invention are achieved by use of a water shield arrangement for use in a friction drive vehicle and a vehicle having same as described herein. 
         [0012]    The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIGS. 1 and 2  are a perspective view and a side elevation view, respectively, of a single wheel structure transportation device having a water guard in accordance with the present invention. 
           [0014]      FIG. 3  is a perspective view of wheel structure  20  without housing  12  (and other components) for use in the device of  FIGS. 1 and 2 . 
           [0015]      FIGS. 4 and 5  are a front end perspective view and a cutaway perspective view, respectively, of one embodiment of water shield arrangements in accordance with the present invention 
           [0016]      FIGS. 6 and 7  are enlarged sectional views from  FIGS. 4 and 5 , respectively. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIGS. 1 and 2 , a perspective view and a side elevation view of a personal transportation device  10  having water shield arrangements in accordance with the present invention are respectively shown. The water shield arrangements are described in more detail below with reference to  FIGS. 3-5 . 
         [0018]    Device  10  has a wheel structure  20  that may include a wheel rim  21  and a tire  23 . While only one tire is shown in  FIG. 1 , more than one tire (for example, two parallel tires) may be mounted to rim  21 . The term “wheel  20 ” may also be used herein and it is intended to mean a wheel structure unless otherwise noted. A housing  12  may cover a portion of wheel structure  20 . Housing  12  covers more of wheel  20  in  FIG. 1  than in  FIG. 2 . Two foot platforms  35 , 36  are provided on opposite sides of the wheel, and housing sections  14  may extend from the main housing  12  and support or define the foot platforms  35 , 36 . Lower leg contact surfaces  37 , 38  that may increase friction and/or be compressive to provide comfort are preferably provided above each of foot platforms  35 , 36 , respectively. 
         [0019]    Housing sections  14  preferably houses drive motors  41  and batteries  51 , and may contain electronic control circuitry  53  (see  FIG. 2 ). A gyroscopic or other suitable position sensor  57  is preferably provided, and may be located towards the top (or elsewhere) of the device. As is known for single wheel structure self-balancing devices, the electronic control circuitry  53  receives position data from sensor  57  and sends drive signals to the drive motor(s)  41  to drive wheel structure  20  toward self-balancing. Suitable batteries, sensors and electronic control circuitry are known in the art. Device  10  may also include indicator and/or pathway lighting  58 . 
         [0020]    Referring to  FIG. 3 , a perspective view of wheel structure  20  without housing  12  (and other components) is shown.  FIG. 3  illustrates one embodiment of a friction drive arrangement (others are taught in U.S. patent application Ser. No. 14/811,702 mentioned above). In the embodiment of  FIG. 3 , rim  21  has a central ridge  24  and two drive surfaces  25 , 26  that preferably slope away from the ridge. Drive head  44  has two surfaces  45 , 46  that are preferably complementary to drive surfaces  25 , 26 . Ridge  24  serves to center drive head  44  on rim  21 . A drive shaft  42  extends from drive motor  41  to head  44 . 
         [0021]    Drive motor  41  may be a suitable drive motor. Many are known in the art. Being lightweight, energy efficient, sufficiently powerful and/or cost-effective are among the criteria for selecting an appropriate drive motor. A significant aspect of friction drive motors is that since they tend to be energy efficient, fewer battery cells are required which lessens vehicle weight considerably. Further, friction drive motors tend to be small which allows for the use of two motors, for example, one to provide redundancy or a slower, safer wind down if another fails. 
         [0022]      FIG. 3  also shows an inner member  61  of a water shield assembly  60  in accordance with one embodiment of the present invention. Inner member  61  and water shield arrangements or assemblies  60  are shown in more detail in  FIGS. 4-7 . 
         [0023]    Referring to  FIGS. 4 and 5 , a front perspective view and a cutaway perspective view of one embodiment of water shield arrangements  60  in accordance with the present invention are respectively shown. Note that for teaching purposes, tire  23  has been removed.  FIGS. 6 and 7  are enlarged sectional views from  FIGS. 4 and 5 , respectively. 
         [0024]    To prevent or significantly reduce moisture movement into the “rim envelope,” the volume defined by the interior or the rim and the two parallel vertical planes that touch the outer edges of the rim (i.e., to eliminate water at the drive head and drive surface), two water shields  60  are provided. The each consist of a pair of overlapping shield members that are termed the inner member  61  and the outer member  71 , where inner and outer are relative to distance from the rim. The inner and outer members are separate and preferably not in contact so that the inner may spin freely without contacting the outer. They are preferably partially overlapping yet to an extent that little or no water enters into the gap between them. 
         [0025]    For each pair, the inner edge  64  of inner member  61  is coupled to rim  21  and the outer edge  65  is preferably larger in diameter than inner edge  64 . Inner member  61  is preferably contoured, sloped, conical or otherwise arranged such that together with rim  21 , a groove or depression  67  is formed between inner member  61  and rim  21 . Water landing on the back side of inner member  61  (visible in  FIG. 4 ) flows into groove  67  and down to the bottom of the wheel where it is expelled by gravity. The attachment between the inner member and the rim is preferably continuous. 
         [0026]    The outer member  71  is preferably mounted to the interior of housing  12  or a like frame or structure (see  FIG. 4-7 ). The inner and outer members are configured such that they overlap, in such a manner that much of the spray off tire  23  drips down groove  67  or  77  in one or the other member. The outer member may be fully circular or partially circular. For example, it can be seen in  FIGS. 4-5  that the outer member ends just below the platform. During installation, the inner member may be slid into the partially annular outer member. 
         [0027]    While, in  FIGS. 5-7 , the inner member fits within the outer member, it should be recognized that this may be reversed such that the outer member fits within the inner member. They are preferably co-axial. 
         [0028]    In the embodiment of  FIG. 4 , inner edge  64  of inner member  61  (the edge which is attached to the rim) has a diameter that is smaller than the diameter of the outer circumference of the rim. The outer edge  65  preferably has a diameter that is greater than that of inner edge  64 . 
         [0029]    The inner edge of the outer member (that closer to the rim) preferably has a diameter larger than that of the outer edge of the inner member, but smaller than the diameter of the wheel. The diameter of the outer member&#39;s outer edge is smaller than that of its inner edge. The attachment between the outer member and the housing is watertight. Thus water coming from wheel  20  onto the outer member stays close to the housing and flows downward away from the top of the ring, eventually falling out of the vehicle onto the ground. Since the outer member partially encircles the inner member, substantially all water carried into the vehicle by the wheel falls onto one of the two members and is directed out of the vehicle. This prevents water from falling onto the interior surface of the rim and causing slippage between the drive member and the rim. (A slight amount of water may happen to reach the rim&#39;s interior surface, but the amount of water is so small as to be negligible. The rapidly rotating drive member will disperse stray droplets and generate heat which helps to dry the rim.) 
         [0030]    The wheel rim water guard of the present invention is useful for a variety of vehicles because it makes friction drive systems more practical, which expands options for lightweight, portable vehicle designs. In particular, this water guard is very important to friction drive designs for vehicles having dynamic pitch balancing, where proper functioning of the balancing system relies on uninterrupted torque. 
         [0031]    It should be noted that while  FIGS. 1-2  illustrate a single wheel structure vehicle, the water shield arrangements of the present invention are applicable to vehicles having 2, 3, or 4 wheels and other wheel number and/or type configurations. 
         [0032]    It should be further noted that if only one guard member is provided, the inner member is more important. Furthermore, the inner member may be coupled to the rim or the tire, and it may be formed integrally with the rim or tire or attached subsequently as an add-on. 
         [0033]    The inner and outer members may be formed of plastic, metal, rubber or rubberized plastic, and/or other suitable materials. 
         [0034]    While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.