Aquatic wheelchair
BACKGROUND OF THE INVENTION 
     Many victims of injury to the brain or spinal cord are left paralyzed and in need of care so that they can continue to live active and productive lives. It was reported in 1988, that the National Institute on Disability and Rehabilitation Research estimated that in the United States alone, there were 300,000 wheelchair-bound paraplegics and quadriplegics; many of whom keep physically active by playing various sports; such as, tennis and basketball, while in their wheelchairs. 
     In order that wheelchair-bound persons may expand their activity to aquatic recreation and aquatic sports, such as, water polo, after considerable research and experimentation, the aquatic wheelchair of the present invention has been devised which comprises, essentially, a main flotation body having a seat portion and a backrest portion, flotation paddle wheels are mounted on the seat portion on each side thereof, and a flotation stabilizer wheel is detachably connected to the backrest portion. The flotation paddle wheels are constructed and arranged to facilitate the convenient grasping of the top portions of the paddle portions of the paddle wheels by the user when seated for manually propelling the wheelchair not only on soft terrain, such as a sandy beach or grass areas, but also in water, such as a pool, lake, bay or ocean. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the aquatic wheelchair of the present invention; 
     FIG. 2 is a top plan view of the aquatic wheelchair; 
     FIG. 3 is a front elevational view of the aquatic wheelchair; 
     FIG. 4 is a rear elevational view of the aquatic wheelchair; 
     FIG. 5 is a view taken along line 5--5 of FIG. 1; 
     FIG. 6 is a view taken along line 6--6 of FIG. 5; 
     FIG. 7 is a view taken along line 7--7 of FIG. 1; and 
     FIG. 8 is an elevational view of another embodiment of an axle assembly to be employed in the aquatic wheelchair of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and more particularly to FIGS. 1 and 2, the aquatic wheelchair of the present invention comprises a main flotation body 1 having a seat portion 2 and an integral backrest portion 3. Flotation paddle wheels 4 are connected to the seat portion 2 on each side thereof, and a flotation stabilizer wheel assembly 5 is detachably connected to the backrest portion 3. The seat 2 and backrest 3 are formed of lightweight polystyrene or other suitable thermoplastic material of closed cell construction, and as will be seen in FIGS. 2 and 3, they are each curved or formed with a concave configuration to enhance the comfort of the occupant. 
     Referring to FIG. 5, it will be seen that the paddle wheels 4 are rotatably mounted on a tubular axle 6 extending transversely of the seat and extending through depending hangers 2a  integrally formed with the seat. 
     The axle 6 is provided with suitable washers 7 positioned and secured on each side of the hangers 2a to reinforce the same and secure the axle 6 thereto, and the outer washers act as spacers for the paddle wheels. The axle 6 is hollow with sealed ends and is therefore buoyant, and a washer and bolt assembly 8 on each end thereof maintains the paddle wheels 4 on the axle 6. 
     The details of the construction of the paddle wheels 4 which are molded of plastics material are illustrated in FIGS. 5 and 6. Each paddle wheel comprises an inner hub portion 4a surrounding the axle 6 and forming the bearing for the wheel. An outer hub portion 4b is spaced radially outwardly from the hub portion 4a, and the inner and outer hub portions 4a and 4b are connected by end walls 4c, to thereby form an annular flotation chamber 4d. A plurality of circumferentially spaced, radially extending spokes 4e are formed integral with the outer hub portion 4b, the spokes being hollow with their outer ends being closed as at 4f and their sides being closed by end walls 4g. The inner ends of the spokes 4e communicate with the annular flotation chamber 4d, as at 4h, whereby the flotation of the wheel is enhanced. In order to reinforce the spokes 4e and to provide ground engaging surfaces in addition to those shown at 4f to facilitate propelling the wheelchair on terrain, incl. soft terrain, the outer ends of the spokes 4e are interconnected by a pair of laterally spaced tubular rings 4i. Experimentation has shown, for example, and not by way of limitation, that an efficiently operating paddle wheel providing the proper amount of buoyancy and thrust, can have a diameter of approximately two feet, a width of approximately eight inches, with the width of each of the ground engaging surfaces of the pair of laterally spaced tubular rings 4i being approximately two inches. The diameter of the annular flotation chamber 4d in such a paddle wheel is approximately thirteen inches. It is preferred that each paddle wheel, for example, has eight spokes. With a wheel having the dimensions given by way of example, each paddle wheel will have approximately 304 square inches of thrusting surface. By way of comparison, a large canoe paddle has approximately 105 square inches of thrusting surface. The two paddle wheels will have more thrusting surface than six canoe paddles, so that the occupant of the chair can propel himself or herself forwardly in the water with ease. 
     Referring to FIG. 1, it will be noted that the construction and arrangement of the paddle wheels 4 relative to the seat portion 2 and backrest portion 3 are such that the wheels 4 are mounted forwardly of the seat and backrest portions, for example, by approximately sixteen inches, to thereby position them for ease of grasping by the occupant of the chair, and by determining the center of gravity, so that the main flotation body 1 will remain in a stabilized position while in the water, the seat portion 2 is inclined upwardly in a direction from the back of the chair toward the front. With the paddle wheels positioned in this manner, the tops of the wheels can become armrests for the occupant when the chair is at rest. The tops of the wheels are at the proper height, so that for propelling the chair forwardly, when floating in the water, the occupant grasps the closed outer ends 4f, that is the top portions, of the spokes 4e with the hands, with the heel portion of the palms bearing against one surface of the spokes and the fingers extending around the closed ends 4f, and by pushing forwardly with the arms the paddle wheels are rotated toward the front of the chair. An occupant who has use of his arms, but not of his fingers, can also propel the chair forwardly, and maneuver the chair in the water, such as by rotating only one wheel for turning the chair. 
     In order that the wheelchair will be stabilized while being propelled on the ground, the stabilizer flotation wheel assembly 5 is provided, the details of which are illustrated in FIGS. 1, 4 and 7. The wheel assembly 5 comprises, a leg or pedestal 5a having a hollow balloon-type wheel 5b rotatably mounted on its lower end. The pedestal 5a, preferably formed from thermoplastic material of closed cell construction, is centered on the longitudinal axis of the seat portion 2 and extends upwardly through an opening 2b provided in the rear of the seat portion 2, and into a communicating passage 3b provided in a curved backrest flotation extension 3a connected to the rear of the backrest 3 and the seat portion 2 behind the backrest 3 to provide additional flotation. The backrest flotation extension 3a is also formed from thermoplastic material of closed cell construction. The upper end of the pedestal 5a is terminated by a tongue 5c which is slidably mounted in a groove 3c provided in the back wall of the backrest 3. The tongue connector 5 c and groove 3c may be correspondingly tapered to removably retain pedestal 5a in connection with the backrest 3. As an alternative, a removable pin, not shown, can be used to removably retain the wheel assembly 5 on the chair. The removable pin, for example, could extend through the rear edge of seat portion 2, into the opening 2b, and into the pedestal 5a. By this construction and arrangement, the wheel assembly 5 can be detachably connected to the main flotation body for purposes of storage or transportation. 
     While the embodiment of the wheelchair as shown in FIGS. 1 to 6 employs a hollow, tubular axle 6 which enhances the overall flotation characteristics of the aquatic wheelchair, FIG. 8 illustrates another embodiment of an axle assembly wherein the paddle wheels 4 are rotatably mounted on stub shafts 9 secured to the hangers 2a. To maintain the lateral stability of the chair, a plastic coated multi-strand tension cable 10 of steel or the like is provided. The end portions of the cable extend through a pair of apertured end caps 11 threadably mounted on the receptive threaded end 12 of the stub shaft 9, the ends of the cable 10 being enlarged as at 10a to prevent their removal from the apertured caps. By reducing the dimensions of the axle assembly, the flow resistance of the chair while being propelled in water is also reduced. Additional tensioning of the cable is provided by threading end caps 11 further onto the threaded ends 12 of the stub shafts. 
     From the above description it will be readily apparent that the aquatic wheelchair of the present invention provides an improved aquatic vehicle, whereby wheelchair bound persons may expand their activity to aquatic sports and aquatic recreation, incl. fishing. The flotation of the wheelchair is enhanced by the lightweight buoyant material of the main flotation body 1, including seat portion 2, backrest 3 and backrest flotation extension 3a; and the pedestal 5a, together with the hollow stabilizer wheel 5b and the various hollow portions of the paddle wheels 4. 
     The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.