Abstract:
A Detachable Drive Unit for a Snowboard includes a low-profile drive belt assembly designed to be mounted underneath a pre-existing, conventional snowboard, and a drive motor which powers the drive belt for propulsion up snow-covered hills or over variable snow-covered terrain. The device is easily removable, compact and lightweight, facilitating its transport in a backpack, allowing the device to remain with the snowboarder while the snowboard is ridden downhill in a conventional manner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of provisional application 60/392,845 filed Jun. 28, 2002, and provisional application 60/393,950 filed Jul. 1, 2002.  
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX  
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    Conventional snowboards use the force of gravity to pull the snowboard and snowboarder down snow-covered slopes, an activity performed for recreation. Part of the appeal of snowboarding may be attributed to the design of the conventional snowboard, which includes a flat bottom without holes or protrusions that glides freely on snow.  
           [0005]    A conventional snowboard utilizes an upwardly curved front end that enables it to rise above and stay on top of snow while in motion, even when the snow is in an uncompressed state, referred to as powder snow. Snowboarding on powder snow provides a softer and smoother sensation than snowboarding on snow that has been compacted or disturbed, usually as a result of having previously been ridden on by other snowboarders or skiers. Because of its soft, smooth nature, snowboarding on powder snow is often found to be a highly desirable aspect of snowboarding.  
           [0006]    Since conventional snowboards are designed to be ridden downhill, a method for transporting a snowboarder to the top of a snow-covered hill must be employed for a snowboarder to be able snowboard in the conventional manner. Among the several methods that exist, paying for the use of uphill lift facilities at a ski resort is currently the most common. At a ski resort, a snowboarder pays a fee that allows the snowboarder to share the uphill lifts and downhill slopes with other patrons. Since the slopes are shared, the amount of powder snow available to snowboard upon after a snowfall is limited, as it is quickly compacted or disturbed as a result of being snowboarded or skied on by the other patrons. In addition, ski resorts can become crowded, affecting the amount of time a snowboarder can spend snowboarding, as well as the safety of the snowboarder while snowboarding.  
           [0007]    Other methods exist for transporting a snowboarder to the top of snow-covered hills that allow a snowboarder improved access to powder snow, and afford benefits of snowboarding where there are no crowds. One of these methods is to use a snowmobile for transportation to the top of a snow-covered hill where few snowboarders or skiers are present. This requires the purchase or rental of a snowmobile which can be expensive or inconvenient, thereby limiting its appeal. Using a snowmobile for snowboarding also requires two or more people, one of whom does not get to snowboard, and instead must drive the snowmobile to the bottom of the hill to meet the other snowboarder or snowboarders. This also prevents a solo snowboarder from using this method for snowboarding.  
           [0008]    Companies exist that offer the service of transporting snowboarders to the top of snow-covered hills using expensive machines such as snow-cats or helicopters, to provide snowboarders enhanced access to powder snow. Since these machines are expensive to purchase and operate and can only transport a small number of snowboarders at once, the fees charged for this service are expensive, thereby limiting the number of snowboarders who choose to utilize this method.  
           [0009]    Snowboarders may also access powder snow and uncrowded snow-covered slopes by hiking uphill in the backcountry. This consumes a great deal of time and energy, and as such, many snowboarders do not consider this a desirable option.  
           [0010]    A power-driven snowboard, described in U.S. Pat. No. 5,662,186 issued to Welch, is capable of transporting a snowboarder up snow-covered slopes on a specialized snowboard to which a motor and drive belt are mounted. The rear portion of the snowboard has a hole cut out of it to accommodate a drive belt that engages with the snow, and the rear portion is angled downward at an angle of approximately 6 degrees. When the Welch snowboard is used to travel downhill, the drive belt interferes with the sliding performance of the snowboard as compared to that of a conventional snowboard, and the weight of the mounted motor and drive unit adversely affects its maneuverability as compared to that of a conventional snowboard. These features detract from the simple, unencumbered design of a conventional snowboard, inherent to the enjoyment of conventional snowboarding. Since the Welch snowboard is a specialized snowboard, if it were ridden downhill without the motor and drive unit attached, the large hole in the rear section and the downwardly angled rear section would likewise impact the sliding performance as compared to that of a conventional snowboard.  
           [0011]    A lightweight, portable power-drive unit is described in U.S. Pat. No. 6,193,003 issued to Dempster. This device is a power driven tractor designed to be situated behind a skier, and may also be situated behind a snowboarder. It employs a rigid pole to provide driving thrust from the tractor to a special belt harness worn by the skier or snowboarder. This device can provide a means of transporting a snowboarder to the top of certain snow-covered hills, however, since the thrust is delivered to the waist of the snowboarder, it can place undesirable stress on the body of the snowboarder, and limit the freedom of posture and muscular control of the snowboarder. In addition, the angle of the drive pole relative to the ground determines, in part, the size of the vertical component of the force that the drive pole imposes downward on the front of the driving tractor. This downward component of force is important to the traction and efficiency of the driving tractor. The rear portion of a conventional snowboard extends a substantial length behind the snowboarder, thus restricting the position of the tractor to a location where the angle of the pole is such that it is difficult to achieve the downward component of force necessary for adequate traction in many situations.  
           [0012]    Also described in the Dempster invention is an attachment enabling the tractor to be situated behind and connected directly to a type of snowboard. If the attachment were implemented in such a way that the tractor could instead attach to a conventional snowboard, and the snowboard remain structurally unchanged, and the tractor capable of removal for the snowboard to be ridden in a conventional manner, when attached the tractor would be situated far behind the weight of the snowboarder making it difficult to apply the pressure necessary to achieve adequate traction in many conditions.  
           [0013]    A need therefore exists for a more efficient and effective device capable of transporting a snowboard and snowboarder to the top of a snow-covered hill under its own power, yet be taken downhill with the snowboarder, allowing the snowboarder to ride the snowboard downhill in a conventional manner without interfering with the sensation offered by conventional snowboarding. The device would be available at the bottom of the hill for the snowboarder to use to return to the top of the hill where the process could be repeated. Such a device would offer a snowboarder enhanced access to powder snow, as it could be used on a hill where no lift facilities exist, and few other snowboarders venture, and it would offer more economical and less restricting alternatives to buying or renting a snowmobile to access powder snow in these areas, or paying for snow-cat or helicopter service. Such a device would offer an alternative to snowboarding at ski resorts which can become crowded and offer limited availability of powder snow, and would offer a more efficient alternative to hiking up snow-covered slopes. Such a device could be used in conjunction with one of the many conventional snowboards already in existence, thereby minimizing production expense, and would offer improved traction performance over prior art by more efficiently utilizing the weight of the snowboarder to provide the downward force necessary for positive traction. Additionally, it could be used to convert a conventional snowboard into a power-driven snowboard whereby the snowboard is driven under motor power at all times, for recreation or utility purposes.  
         BRIEF SUMMARY OF THE INVENTION  
         [0014]    The present invention provides a compact and lightweight detachable drive unit for a pre-existing conventional snowboard that can be easily attached to and removed from a conventional snowboard without requiring structural alteration to the snowboard. When attached, it offers a powered means of transporting a snowboard and snowboarder to the top of a snow-covered hill. It can then be removed from the snowboard and carried with the snowboarder in a backpack or back harness, allowing the snowboarder to ride the snowboard downhill in a conventional manner, without interfering with the sensation offered by conventional snowboarding as experienced with prior art. Since the drive unit is mounted under the snowboard, the weight of the snowboarder is more optimally utilized to provide the downward pressure necessary for positive traction, overcoming traction problems of prior art. The invention can also be used to temporarily or permanently convert a conventional snowboard into a power-driven snowboard whereby the snowboard is driven under motor power at all times for recreation or utility purposes.  
           [0015]    The drive unit is comprised of a drive belt supported by at least two rollers housed in a low-profile frame, and is mounted to the underside of the rear portion of a pre-existing conventional snowboard. The drive unit is driven by a motor mounted above the rear portion of the snowboard. The drive belt is designed to grip snow, and when driven by the motor, propels the snowboard and snowboarder up a snow-covered hill, or over snow-covered terrain. A snow compression plate is attached in front of the drive unit to provide a gradual transition from the underside of the snowboard to the underside of the front of the drive belt. The conventional snowboard used with the drive unit remains structurally unaltered, and as such, is still capable of providing the snowboarder with the experience of conventional snowboarding when the drive unit is detached.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a side view of the invention mounted on a conventional snowboard.  
         [0017]    [0017]FIG. 2 is a cut-away side view of the invention mounted on a conventional snowboard.  
         [0018]    [0018]FIG. 3 is a perspective side view of the invention dismounted from the snowboard, showing one possible mounting procedure.  
         [0019]    [0019]FIG. 4 is a depiction of the invention being transported in a backpack while the user snowboards in a conventional manner, with a cut-away view of the backpack to show the contents.  
         [0020]    [0020]FIG. 5 is a top view of the implemented drive roller.  
         [0021]    [0021]FIG. 6 is a top view of the implemented drive belt.  
         [0022]    [0022]FIG. 7 is a perspective view of the implemented drive belt.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIG. 1 depicts a side view of the Detachable Drive Unit for a Snowboard attached to a pre-existing conventional snowboard ( 10 ). The drive unit ( 20 ) is mounted to the underside of the rear portion of the snowboard ( 10 ), and is powered by a motor ( 50 ). The motor ( 50 ) is mounted on top of the rear portion of the snowboard ( 10 ).  
         [0024]    The drive unit ( 20 ) consists of a frame ( 21 ) that serves as support for the cylindrical drive roller ( 24 ) and lead roller ( 25 ) on which the drive belt ( 70 ) travels, depicted in FIG. 2. The drive unit ( 20 ) includes an upper surface ( 22 ), illustrated in FIG. 3, that can support the weight of the snowboard ( 10 ) and snowboarder ( 11 ) with minimal flexing, without damaging the underside of the snowboard ( 10 ), and without impeding the movement of the drive belt ( 70 ). The drive unit frame ( 21 ) is open at the rear to facilitate ejection of snow from the drive belt ( 70 ). The drive unit frame ( 21 ) is attached to the motor ( 50 ) using tabs ( 23 ) that extend beyond the side edges of the snowboard ( 10 ) and mount to corresponding tabs ( 52 ) on the motor mounting plate ( 51 ), depicted in FIG. 3.  
         [0025]    The motor ( 50 ) is mounted to a motor mounting plate ( 51 ) and situated on top of the rear portion of the snowboard ( 10 ) behind the rear binding ( 13 ). The motor mounting plate ( 51 ) is attached to the drive frame ( 20 ) using mounting tabs ( 52 ) that are fastened to the tabs on the drive unit ( 23 ) using quick-release clamps or bolts. This also secures the motor ( 50 ) and drive unit ( 20 ) around the snowboard ( 10 ).  
         [0026]    Forward motion between the drive unit ( 20 ) and motor ( 50 ), and the snowboard ( 10 ), is restricted by positioning the motor mounting plate ( 51 ) directly behind the rear edge of the rear snowboard binding ( 13 ). Backward motion is limited by a front mounting plate ( 53 ) situated on top of the snowboard and in front of the rear binding ( 13 ), that attaches to tabs ( 32 ) at the front of the drive unit frame ( 21 ). The mounting plate ( 53 ) has a screw adjustment that can be extended to meet the front edge of the rear binding ( 13 ). To prevent unwanted sideways movement, adjustable spacers are positioned between the tabs ( 23 ) and ( 52 ), that extend inward to meet the edges of the snowboard.  
         [0027]    The cylindrical lead roller ( 25 ) is freely rotating and small in diameter in order to create a low profile at the front end of the drive unit ( 20 ), allowing the drive unit ( 20 ) to remain relatively streamlined and offer little resistance to the snow through which it travels. With the aid of the belt tension adjustor ( 31 ), the lead roller ( 25 ) can be moved closer to or further away from the drive roller ( 24 ) to achieve proper belt tension.  
         [0028]    The drive roller ( 24 ) is located at the rear of the drive unit ( 20 ), and includes a drive sprocket ( 28 ) attached to a drive axle ( 27 ) that allow the drive roller ( 24 ) to be driven by roller chain ( 56 ) from the motor sprocket ( 55 ). The drive roller ( 24 ) transmits power to the drive belt ( 70 ) using a series of tapered teeth ( 26 ) present on the surface of the drive roller ( 24 ) that engage with holes ( 72 ) in the drive belt ( 70 ), as shown in FIGS. 5 and 6. The drive roller ( 24 ) has a larger diameter than the low-profile lead roller ( 25 ), creating an angled path for the lower portion of the drive belt ( 70 ), as depicted in FIG. 2. The angled path enhances traction between the drive belt ( 70 ) and the snow, and increases alignment of the lower surface of the track with the snow compression plate ( 60 ) for a more streamlined underside. The larger diameter of the drive roller ( 24 ) also allows for a sufficient number of drive teeth ( 26 ) to be employed to securely drive the drive belt ( 70 ).  
         [0029]    Illustrated in FIGS. 6 and 7, the drive belt ( 70 ) incorporates a thin design capable of rounding small diameter rollers, and includes a series of cleats ( 71 ) that extend outward from the surface of the drive belt ( 70 ) and across the width of the drive belt ( 70 ) which provide traction in snow. Cleats of substantial height are utilized for high performance in the powder snow likely to be encountered when using the invention, however, the drive belt can be replaced with one with smaller or different sized cleats for other snow conditions. A staggered, alternated or partial cleat design may also be used for improved performance in extremely loose snow, as practiced in the design of snowmobile tracks.  
         [0030]    The lower portion of the drive belt ( 70 ) is supported from the inside using a flat conveyor belt type slider bed ( 41 ) attached to the sides of the drive unit frame ( 21 ). The surface of the slider bed ( 41 ) is faced with a material that presents low friction to the drive belt ( 70 ), such as Teflon or ultra-high molecular weight polyethylene (UHMWPE). An upper slider bed ( 40 ) may also be incorporated to support the upper surface of the drive belt ( 70 ). The front end of the lower slider bed ( 41 ) includes an internal belt wiper plate, accompanied by small snow ejection holes in the sides of the drive unit frame ( 21 ) located behind the front roller ( 25 ) which help expel snow that may accumulate inside the drive unit frame ( 21 ). The drive roller ( 24 ), lead roller ( 25 ) and slider beds ( 40 ) and ( 41 ), are removable to facilitate replacement of the drive belt ( 70 ).  
         [0031]    The sides of the drive unit frame ( 21 ) extend below the lower surface of the drive belt ( 70 ), but not beyond the tips of the cleats ( 71 ). The extended sides function as a belt guide preventing the drive belt ( 70 ) from deviating from its desired path. When the device is used on compressed snow, the extended sides also act as sleigh runners, supporting some of the weight of the snowboarder ( 11 ), thereby reducing excessive pressure on the cleats ( 71 ), yet the sides offer little resistance in powder snow.  
         [0032]    A snow compression plate ( 60 ) is mounted between the lower portion of the front of the drive unit ( 20 ), and a location on the underside of the snowboard ( 10 ) closer to the front of the snowboard ( 10 ), as depicted in FIGS. 1, 2 and  3 . The snow compression plate ( 60 ) serves to gradually transition the underside of the front of the snowboard ( 10 ) towards the bottom portion of the drive belt ( 70 ) near the lead roller ( 25 ), preventing the blunt front end of the drive unit ( 20 ) from becoming a hindrance to forward motion. When the snowboard ( 10 ) is ridden with the drive unit ( 20 ) attached, some upward flexing occurs at the front of the snowboard ( 10 ) due to the centralized downward force of the weight of the snowboarder ( 11 ), causing the of the front end of the snowboard ( 10 ) to align itself with the plane of the snow compression plate ( 60 ) and the bottom portion of the drive belt ( 70 ) creating a continuous underside that travels efficiently in snow. The bottom of the snow compression plate ( 60 ) is composed of a material on which snow slides easily, such as UHMWPE. The front of the snow compression plate ( 60 ) is affixed to the snowboard ( 10 ) with tabs ( 61 ) located on the front of the compression plate ( 60 ) that extend beyond the side edges of the snowboard ( 10 ), and attach to a mobile attachment plate ( 62 ) on top of the snowboard ( 10 ). The mobility of the attachment plate ( 60 ) allows it to slide forward and backwards when the snowboard ( 10 ) flexes during operation. The rear portion of the compression plate ( 60 ) is attached to the front of the drive unit with a removable attachment pin ( 63 ). The pin ( 63 ) allows the snow compression plate ( 60 ) to pivot when the snowboard ( 10 ) flexes during operation.  
         [0033]    The motor ( 50 ) includes a centrifugal clutch, and transmits power to the drive roller ( 24 ) using sprockets ( 55 ) and ( 28 ), and roller chain ( 56 ). For most compact gas combustion engines a gear reduction unit ( 54 ) must be employed, and located between the motor ( 50 ) and the motor sprocket ( 55 ) in order to provide the drive roller ( 24 ) with the proper rotational speed and torque. The motor sprocket ( 55 ) extends beyond the edge of the snowboard ( 10 ), and is connected by roller chain ( 56 ) to a sprocket ( 28 ) attached to the drive roller ( 24 ), which extends similarly beyond the edge of the snowboard ( 10 ). A spring-loaded chain-tensioning device ( 30 ) is used to maintain proper chain tension, and facilitates installation and removal of the chain ( 56 ). The snowboarder ( 11 ) is able to control the amount of power supplied by the motor ( 50 ) with a handheld throttle device ( 80 ) connected to the motor ( 50 ) with a flexible cable. The handheld throttle device ( 80 ) includes a motor kill switch that enables the user to quickly stop the motor ( 50 ) if necessary.  
         [0034]    The entire invention is designed to be lightweight and compact, and easily detached from the snowboard ( 10 ) and placed in a backpack ( 81 ) designed to accommodate the invention. In this way, the detachable drive unit may be transported with the snowboarder ( 11 ) as the snowboarder ( 11 ) rides the snowboard ( 10 ) downhill in the conventional manner, and be available to the snowboarder ( 11 ) when necessary.  
         [0035]    Several variations of the preferred embodiment exist that may enhance, diminish or otherwise alter the design of the invention, while preserving the ability for the invention to perform its designed function. These include, but are not limited to:  
         [0036]    The top motor unit and lower drive unit may be constructed as a single structural member connected on the sprocket side that allows the device to slide onto the rear section of the snowboard from the side, simplifying the attachment and removal process. A thin plate may be mounted under the rear binding of the snowboard that includes a tab to which the motor and drive unit may be securely attached and detached, yet not interfere with the performance of the snowboard when the device is removed and the snowboard is ridden in a conventional manner. The lower and upper slider beds can be replaced with rollers designed to support the inside of the lower and upper portions of the drive belt. The upper slider bed, or support in this area, may alternately be omitted entirely. The gas motor may be replaced with a battery-powered standard electric motor or an electric internal drum motor, or other suitable powering device. The drive unit may be located elsewhere under the snowboard, such as closer to the middle of the snowboard, and the motor may be located elsewhere, such as on top of the middle of the snowboard. The drive roller may use any effective method to transfer power to the drive belt, such as through friction from a vulcanized rubber coating or knurling on the drive roller, or by other means. Power can be transferred from the motor to the drive roller by other methods, such as by using beveled gears and shafts, a flexible drive cable, a pulley belt, or by other suitable means. The lead roller and rear roller can be any size and relationship to each other as long as they provide adequate performance. The sides of the drive unit do not necessarily need to extend below the lower portion of the drive belt to serve as drive belt guides, or to support user weight, or for any other means. The snow compression plate can be designed in alternate ways, such as by using a wedge or other design, and/or employ other methods of attachment to the drive unit and to the snowboard, so long as it serves the same purpose as the snow compression plate.  
         [0037]    The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.