Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1999-11-16
2001-08-07
Oberleitner, Robert J. (Department: 3613)
Land vehicles
Wheeled
Occupant propelled type
Reexamination Certificate
active
06270105
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention generally relates to wheelchairs, and more specifically to a method of wheelchair construction and resulting wheelchair.
2. Description of the Prior Art
There are two commonly used wheelchair design—the crossbrace folding wheelchair and the welded rigid frame wheelchair. The typical method of construction for both types of wheelchairs is to weld or braze metal tubes together to form frames and folding members. Unfortunately, the two above-described designs have one major flaw in common—the strength inconsistencies of the welded joints. Breakage of welded or brazed joints is the main cause for structural failure in wheelchairs. Welding or brazing also creates a heat-affected zone weakening the frame tube around the welded or brazed joints and making repairs in most cases impossible. Repairs and maintenance of these wheelchairs are costly and require elaborate service infrastructure. In addition, the welded construction makes it extremely difficult, if not impossible, to adapt the wheelchair to the end user's changing needs and environment. Conversion from rigid frame to a folding wheelchair is also virtually impossible.
It is desirable to have a wheelchair design constructed without welds or brazes. A weld-free wheelchair design would eliminate the shortcomings described above and open the door to endless new design possibilities.
Some wheelchair manufacturers build each of the wheelchair types listed above but they are of dedicated, welded construction and, for the aforementioned reasons, do not adapt from one type to another. There are chairs that are modular in design and can change the widths of the wheelchair with little difficulty. There is a design that converts from a user propelled to an assistant propelled wheelchair (U.S. Pat. No. 5,294,141). There is also a wheelchair that converts the riding position from the standard seating position to a recumbent position (U.S. Pat. No. 5,011,175). There is a weld-free folding wheelchair that folds in a non-conventional manner but is not modular (U.S. Pat. No. 4,682,783). Another wheelchair design appears to be a weld-free design that allows the wheelchair to adjust to different needs by use of special shaped bars and plates but is limited to width and depth adjustment (U.S. Pat. No. 5,743,545). There are several U.S. patents that claim to be modular, allowing for different components to be used to build the chair to the user's needs. Among these is a rigid frame wheelchair (U.S. Pat. No. 5,421,598), but again this wheelchair does not convert or adapt to the extent of this invention. There are several U.S. patents for wheelchairs that have welded or brazed construction.
In U.S. Pat. No. 5,253,888, issued to the assignee of the subject invention, a rigid frame weld-free wheelchair is disclosed that utilizes a series of special clamps for clamping tubes to each other. However, such weld-free construction has some disadvantages. A series of specially designed clamps had to be utilized which were not universal to all designs, making further design changes virtually impossible. Also, by virtue of the clamp designs, numerous bolts were required that were clearly visible and detracted from the appearance of the wheelchair.
There are no wheelchairs known to exist at this time that are constructed with distortion-free connectors and that can be configured or adapted to the extent of this design.
SUMMARY OF THE INVENTION
An object of the invention is to provide a method of wheelchair construction and resulting wheelchair that do not have the disadvantages inherent in the comparable prior art.
It is another object of the invention is to provide a lightweight and economical wheelchair that can quickly and easily be sized, adapted or converted. The weld-free construction allows for considerable increase in strength and durability and minimal maintenance.
It is another object of the invention to provide a modular construction wheelchair that can be quickly and easily converted from rigid frame to folding, to sports, to companion chair, etc.
It is another object of this invention to provide a wheelchair that has the ability to adapt to virtually any configuration or option required by the wheelchair user.
It is yet another object of this invention to provide a wheelchair that can be constructed of non-specific tubular materials (steel, aluminum, stainless steel, titanium) and connector fittings which allows to adapt the wheelchair to any environment.
It is another object of this invention to provide a wheelchair built with standardized components which allows it to be shipped in parts and be assembled and customized locally by an unskilled person using simple tools.
The resulting wheelchair has a pair of like side frame assemblies spaced from each other and each including a generally horizontal seat tube and a generally horizontal bottom tube below the seat tube. Each of the seat and bottom tubes have front and rear ends. The wheelchair also has a generally vertical backrest tube having a lower end proximate to the rear ends of the seat and bottom tubes and an upper end that extend upwardly of the seat tube and form handgrips. The wheelchair has a caster assembly for each side frame assembly carrying a caster wheel and having a generally upwardly extending shaft portion, at least one failsafe weld-free means for each of the frame assemblies rigidly connecting at least two tubes of the wheelchair to each other and transverse connecting means for extending between and connecting said side frame assemblies to each other.
This wheelchair also has footrest supports secured to said seat tube and rear wheels mounted on the side frame assemblies.
The typical wheelchair frame is made up of left and right side frame assemblies, two push handle assemblies, upholstery and removable folding or rigid crossbars. There are specially designed failsafe weld-free connector fittings that are used to provide for a secure fastening internally between mating tubes. These fittings are used throughout all assemblies where two or more tubes mate up. These fittings shall be referred to as connector fittings throughout this text. Each side frame assembly is provided with mounting holes to assemble the wheelchair as either folding or rigid. The folding crossbar assemblies have T-type fittings at the lower end which are a sliding fit to the lower side frame assembly tubes. At the top of the crossbars are seat tubes held in place perpendicular to the crossbar by the connector fittings. Each seat tube is assembled with a multi position insert that is used to attach the seat tube to the crossbar and to assemble the seat upholstery. There are holes in the crossbars near the center. These holes are the location where a pair of crossbars are bolted together and act as the pivot point when folding. These crossbars are slid onto the lower frame tube and held in place with retaining rings fastened through holes in the tube. This maintains proper horizontal position. There are also holes near the top of the crossbars that are fastened to links that pivot on the side frame assemblies. The links hold the wheelchair frame assemblies parallel when the chair is in both the open (riding) and folding (storage) positions. When the wheelchair is in the open (riding) position, the seat tubes nest into saddles fastened to each side frame assembly. This nesting along with the tension of the upholstery creates a solid box frame giving the chair the feel and performance associated with rigid frame wheelchairs.
Rigid frame type wheelchair use different cross tubes and back assembly. The rigid frame does not use the folding crossbars, links, and retaining rings which are specific to the folding wheelchair. There are two types of rigid crossbars. The lower crossbars are straight tubes. The upper crossbars have a bend at both ends to give clearance at the seat and back upholstery. Each of the rigid crossbars is assembled with the connector fittings. The same seat inserts in the folding design are inserted into the upper frame
Bartz C. T.
Da International, Ltd.
Lackenbach Siegel Marzullo Aronson & Greenspan P.C.
Oberleitner Robert J.
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