Abstract:
A land paddle having energy storage and recovery capability is provided. The disclosed devices absorb user energy during a paddling stroke and release the energy at the end of the stroke. The force needed to store energy is progressive. In this way, heavier, stronger or taller users and lighter, weaker or shorter users are able to use the device without limitation.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates generally to sporting goods and sporting activities and, more particularly, relates to a propulsion means and system for use by a participant to paddle over land. 
       BACKGROUND 
       [0002]    In the area of water sports, it is known to paddle a sport craft for propulsion. Examples of such craft include kayaks, canoes, paddle boards, and so on. Certain non-sport craft such as row boats also use one or more paddles for propulsion. In their use for water propulsion, paddles are convenient, though somewhat inefficient due to turbulent losses and other hydrodynamic inefficiencies. The energy lost in this manner is wasted and cannot be stored or later reused. 
         [0003]    The possibility of using a type of paddle to propel a rider of a wheeled craft on land has recently come to light. In particular, the rider of a skate board, long board, or other wheeled personal conveyance may hold a staff or stick for propulsion. The end of the paddle is periodically forced into the ground and backward to propel the skate board or other conveyance forward. This motion is similar in appearance to the paddling motion used when paddling water-borne craft. 
         [0004]    As with water craft, there are inefficiencies that occur when paddling a land borne conveyance. For example, the paddling resistance is not necessarily a good match for the rider&#39;s strength. As such, the rider may push with all their strength, but only cause a small displacement of the conveyance. The rider&#39;s strain during such a maneuver is essentially wasted. Moreover, if the rider swings the paddle downward on each paddling stroke, the sudden contact of the paddle with the ground may cause the paddle to slow suddenly, causing shock and potential injury to the rider, especially the rider&#39;s arms and shoulders. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The disclosure includes the following figures, which are provided so that the reader may better understand the invention. 
           [0006]      FIG. 1A  is a simplified schematic view showing an implementation of a version of the invention using an external elastic element energy absorption mechanism, with the device in an compressed position; 
           [0007]      FIG. 1B  is a simplified schematic view showing an implementation of a version of the invention using an external elastic element energy absorption mechanism, with the device in a extended position; and 
           [0008]      FIG. 2  is a partial cut away drawing showing an alternative version of the invention wherein internal elastic or elastomeric bands or bunches are used in tension for energy storage. 
       
    
    
       [0009]    The figures are not necessarily drawn to scale and are not intended to convey precise dimensions, since precise dimensions are not critical. The figures and text show and discuss examples, but it will be appreciated that many other variations fall within the described invention. 
       DETAILED DESCRIPTION 
       [0010]    As was discussed above it is possible for a rider to use a paddle to propel themselves on land via a wheeled craft such as a skate board. However, as also noted, the paddling resistance may not be a good match for the rider&#39;s strength, causing undue strain and wasted energy. Also, the sudden contact of the paddle with the ground during use may cause shock and potential injury to the rider. Thus, the inventor has conceived of a portable system for storing and releasing user energy while also diminishing the shock induced as the paddle strikes the road surface. The described invention works with a minimum of complication and expense. 
         [0011]      FIGS. 1A and 1B  are partial cut away views of a skate stick  100  or land paddle according to an embodiment of the discussed invention (with the device being compressed in  FIG. 1A  and at rest in  FIG. 1B ). Although the overall length of the paddle is not critical and indeed the paddle may be made in various sizes to accommodate various size users, a paddle of about 5 or 6 feet long would be suitable for many adult users. The paddle includes a handle portion 100 to be grasped by the user, in a similar manner as a water paddle, as well as a shaft portion ( 101 ,  102 ). In the illustrated embodiment, the handle portion  100 , is shown connected to the first tubular portion  101  of the shaft via a screw, pin or other connection. In a particular example, the handle portion  101  is connected to the first tubular portion  102  via an adjustable pinned section to allow for an adjustment of the overall length of the assembled paddle. 
         [0012]    A second tubular portion  102  is configured with a slightly smaller outer diameter or slightly larger inner diameter than the first tubular portion  101  so as to telescope slidingly into or outside of the first tubular portion  101 , allowing the assembled paddle to compress. For storing the user&#39;s energy, an elastic element  104  is provided. The elastic element  104  in the illustrated embodiment is restrained to the second tubular portion  102  by way of a through-pin  106  and is linked to the first tubular portion  101  via a second pin  105  that extends through a slot  107  in the second tubular portion  102 . 
         [0013]    In this way, compression of the paddle serves to stretch the elastic element  104 , storing the input energy for later release as propulsion. A foot or contact component  103  is affixed to the ground-facing end of the second tubular portion  102 , allowing the paddle to grip the ground during the compression and release phases as the user propels the wheeled conveyance. In the figure shown, the contact component  103  is pinned to the second tubular portion  102  by a pin  108 , but any suitable attachment mechanism may be used. 
         [0014]    In an embodiment, the compression range of the paddle shown in  FIG. 1  may be much greater, e.g., 12″ or more, than would be used for mere shock absorption. This is clearly different from systems whose primary purpose is shock absorption or steering and stability, and whose travel is thus on the order of about 6″. The much longer travel of the present device allows not only for retaining a shock absorption function but also allows for efficient storage and release of user energy over a range similar to the range of motion during a paddling stroke. That said, it is also possible if desired to utilize a much shorter range of travel, i.e., less than 12″. 
         [0015]    The partial cut away drawing of  FIG. 2  shows an alternative version of the invention wherein elastic or elastomeric bands or bunches are used internally in tension for energy storage. In the illustrated example, the handle  201  is inserted into the length adjustment  202  and the length adjustment is then inserted into the outer top shaft  203 . The length adjustment can be set to best suit the user in an embodiment. A pin and collar  204  are situated in a thicker portion of the outer top shaft  203 , at the bottom of the outer top shaft  203 , in order to engage the internal shaft  207 . The pin runs through the collar  204 , the mid shaft slot  211 , and an internal shaft pin hole when all of the pieces are assembled. 
         [0016]    For assembly, the bottom internal shaft  208  is slid into the top mid shaft  209 . Once the internal shaft is connected into the top mid shaft, the top internal connection pin  205  is connected from the mid shaft  209  into the top internal connection. Once the top internal shaft  205  and mid shaft  209  are locked in place, the top of the mid shaft  209  is inserted into the bottom of the outer shaft  203 . When all shafts are in place, a pin is inserted through the collar  204 , and follows through the mid shaft slot  211  through the internal shaft pin hole, locking the collar  204  and the bottom internal shaft and pin hole together, allowing the pin to move freely up and down the mid shaft slot  211 . The bottom grip  212  is then inserted and locked into place at the bottom of the mid shaft  210 , giving a point of contact and grip with the ground. 
         [0017]    Once the components in  FIG. 2  are connected, the handle  201  and outer shaft  203  are gripped and pushed down to contact the bottom grip  212  with the ground. Once contact with the ground is made, the elastic band  206  stretches and upon recoiling propels the rider in a forward motion as the elastic band  206  returns to its prior state. The elastic band may provide some shock absorption but primarily provides returned energy in the form of propulsion. It will be appreciated that the state of the elastic band  206  in the resting state of the device may be a pre-stressed state. 
         [0018]    In a further option applicable to all embodiments, the compression resistance may be tuned to the rider&#39;s size and/or strength preference. For example, with respect to tension elements such as bungees, the length, pre-stress or number of such elements may be adjusted to alter the force required to stretch the element. 
         [0019]    Although certain examples have been shown and discussed herein, those of skill in the art will appreciate numerous variations and alternatives based on the given examples. As such, the scope of the disclosed invention is to be limited only by what would be appreciated by those of skill in the art, not by the exact details of any given example. Further, it will be appreciated that features of different examples may be combined in part or in whole without departing from the scope of the invention.