Patent Application
20060076822
1. Field of the Invention
This invention relates to an improved wheel assembly and wheelchair, and in particular to a wheel assembly having multiple small rotatable wheels mounted laterally on a main wheel whereby lateral movement as well as forward and backward movement is possible.
2. Description of the Prior Art
Wheelchairs are available in a variety of shapes and sizes. The traditional wheelchair design, whether powered, manual or pushed by another person, has two main, large diameter, side mounted wheels having fixed parallel positions and having hand rails attached thereto. Because of the fixed parallel positions of the main wheels, movement is generally restricted to pivoting, straight line or curved movement. Curved and pivoting movement is attained by rotating the main wheels at different speeds or in opposite directions. However, the wheelchair cannot achieve side-to-side lateral motion.
In order to shift position laterally, a wheelchair operator must back up, pivot, move forward, pivot, and move forward again. This may be tolerable in some situations; however, the inability to move laterally causes significant difficulty in maneuvering in tight quarters such as bathrooms and elevators. Even in a confined office or work setting, the constant backing and pivoting is time consuming and unproductive.
Transport wheelchairs utilizing four small wheels that rotate have been developed that enhance mobility in tight quarters. However, this type of chair requires the constant presence of an assistant since it cannot be hand propelled.
Thus, there is a need for hand-propelled wheelchairs that can be moved laterally as well as in the standard forward-reverse movement. There is also a need for a wheel assembly that can move laterally as well as forward and backward.
A wheel assembly, wheelchair and method are provided by the present invention. A wheel assembly of the invention that is capable of forward-reverse movement as well as lateral movement comprises a main wheel rotatable on an axle and a plurality of small rotatable outer wheels positioned laterally on the main wheel. The main wheel is rotatable in a plane on the axle and each outer wheel is rotatable on the main wheel in a second plane perpendicular to the first plane.
In a preferred wheel assembly, a plurality of small rotatable outer wheels are attached laterally to the main wheel by ball bearings. In one embodiment, the outer wheels each comprise an inner race, a ring of ball bearings, an outer race, and a tire mounted on the outer race. In another embodiment, each outer wheel comprises a hub having fixed outer hub sides and an outer circumference on which a tire is disposed. A pair of bearing cones are positioned on the main wheel between the hub the outer hub sides.
A wheelchair of this invention comprises a pair of main wheels attached to hubs that rotate on axles by a plurality of spokes. Small outer rotatable wheels and wheel bearings are positioned on the main wheels between the spokes. The small outer rotatable wheels are positioned perpendicularly to the main wheels as close together as possible. The outer tire surfaces of the small rotatable wheels define an essentially continuous wheel assembly circumference. Preferably, the outer tire surfaces are shaped to maximize the circularity of the wheel assembly circumference. An optional brake assembly is attached to the wheelchair for preventing the outer small rotatable wheels from rotating when the wheelchair is moved forward or backward.
The wheelchair of this invention comprises a frame, one or more axles, a pair of rearward main wheel assemblies as defined above attached to the one or more axles and a pair of front castor wheels. The wheelchair is hand-propelled using hand rails mounted on the main wheels and as mentioned above, it can optionally include a brake assembly for preventing rotation of the small outer rotatable wheels.
A method of moving the hand-propelled wheelchair of this invention laterally comprises the steps of releasing the small rotatable wheel brake if included and exerting a lateral force against a proximate object. The lateral force can be exerted by a person or patient in the wheelchair or by an attendant.
The features and advantages of the present invention will become readily apparent to those skilled in the art upon a reading the following description of preferred embodiments taken in conjunction with the accompanying drawings.
As mentioned, a wheel assembly of this invention is capable of forward-reverse movement as well as lateral movement. Referring to
Referring still to
A rolling movement is achieved by the main wheel assemblies 20 and 21 rotatably mounted on one or more axles 22 attached to the rearward portion of the frame assembly 16. The castor wheels 23 and 24 are attached to the front portion of the frame assembly 16. The wheelchair can be hand-propelled without an attendant by using the hand rails 26 and 27 connected to the main wheel assemblies 20 and 21.
The main wheel assemblies 20 and 21 of this invention comprise main wheels 30 and 32, radially extending spokes 34 and 35 and central hubs 36 and 37. Bearings 38 and 39 are mounted in the hubs 36 and 37 which facilitate rotation of the main wheel assemblies about the one or more axle or axles 22. The main wheels 30 and 32 are of a large diameter compared to the smaller castor wheels 23 and 24 to facilitate hand-propelling of the wheelchair.
While conventional hand-propelled wheelchairs generally have tires mounted on main wheel rims, the main wheels 30 and 32 of the wheelchair of this invention are formed of metal or other strong material. In order to allow the wheelchair 10 of this invention to move laterally, a plurality of small laterally positioned rotatable outer wheels 40 and 42 are attached to each of the main wheels as shown in
The number of laterally positioned rotatable outer wheels 40 and 42 that are mounted on the main wheels 30 and 32 can vary in wheelchairs and similar applications. However, in wheelchairs it is best to utilize a large number of closely mounted narrow lateral wheels to thereby make the main wheels as circular and smooth riding as possible.
Referring now to
As mentioned above, the placement of the outer lateral wheels 40 and 42 on the main wheels 30 and 32 should be close together leaving only the space necessary for the spokes 34. Relatively small spaces between the outer wheels provide a smoother ride. Also, shaping the outer tires with a curvature similar to the main wheel curvature rather than flat will improve the smoothness of forward-reverse movement.
A lateral braking system can be provided to prevent the outer lateral wheels 40 and 42 from rotating while the wheelchair is in normal forward-reverse operation. This may not be necessary on level floors such as in a hospital or home, but is necessitated on a slope. When a lateral movement is desired, the lateral brake is released and a stationary object, such as a wall in an elevator or a restroom door, is pushed against by a person or patient in the wheelchair or by an attendant to provide the force necessary to cause the wheelchair to move laterally.
An example of a lateral braking system 60 that can be utilized is shown in
Undesired lateral motion is prevented by applying a lateral braking system, such as the one described above, to the outer lateral wheel assemblies of a single main wheel. It is possible, but not necessary, to apply a lateral braking system to both main wheels. Also, other lateral braking systems can be used that are known and understood by those skilled in the art.
A method of this invention for laterally moving a hand-propelled wheelchair of this invention comprising wheel assemblies capable of forward-reverse motion as well as lateral motion, the wheel assemblies including main wheels mounted rotatably on one or more axles, a plurality of small rotatable outer wheels laterally positioned on the main wheels and a brake for preventing the rotation of the small rotatable outer wheels comprises the steps of: releasing the brake; and causing the wheelchair to move laterally by exerting a lateral force against a proximate object.
While certain preferred embodiments of the invention have been illustrated and described for purposes of the present disclosure, numerous changes in the design and arrangement of parts and steps may be made by those skilled in the art, which changes are encompassed within the scope and spirit of the present invention as defined by the appended claims.
