Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
2000-03-03
2002-07-02
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Occupant propelled type
C280S250100, C180S065510
Reexamination Certificate
active
06412804
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the technical field of wheelchairs, especially for persons who are handicapped or elderly, or suffering from a disease.
2. Description of Related Art
The present invention relates to the technical field of wheelchairs, especially for persons who are handicapped or elderly, or suffering from a disease.
It is common knowledge that aside from a certain, very limited, improvement in comfort, and new elements such as electrical motorization, wheelchairs have not changed much from a technological perspective. To date, the best of them are constituted by a cycle part and a seat part, the cycle part being rudimentary in its design. In the prior art, the two parts are still considered globally by manufacturers, which partially explains the serious defects and disadvantages that remain. At best, overall changes have been made without providing any drastic improvement in a particular area.
The chief serious defects or disadvantages that still characterize the prior art after decades are:
vibrations on any rough or frequently uneven surface such as black top, gravel, cobblestone, the paving stones of pedestrian walkways, indoor or outdoor stone or tile, and the like, which are difficult, even painful for users;
the difficulty of negotiating obstacles such as sidewalks, steps, and the like, when ascending or descending;
the lack of shock absorption of any kind,
the risk of overturning in case of banked curves;
the seat of the chair, which is very poorly adapted, or non-adaptable, to the particular situation and hence to the comfort of the person in question; there is no real support of the individual, which in addition to mere discomfort, creates a risk of the person's slipping and falling.
At present, two main types of wheelchairs are known.
There is a standard collapsible wheelchair, which is subject to Social Security reimbursement, and with which hospitals, homes for the elderly, various centers involved with the problems of the handicapped, and certain service organizations are equipped. The assistance of a third person is required for its use, particularly for negotiating obstacles; this chair is heavy and difficult to handle, and storing it has proven to be complicated.
There is also a lightweight chair that can be considered to be a “sport” chair, collapsible or non-collapsible, better looking and easier to handle, which is aimed at a clientele of independent users who seek greater autonomy and/or have to perform exercises.
Many changes have appeared for making these chairs more adaptable between ordinary and “independent” or “sport” use, but the defects mentioned above have not been eliminated. This is especially true for the kinematic part, the suspension, the flexibility of the wheel trains, the filtering of vibrations. The prior art has been limited to providing a change in the camber of the wheels (i.e., the angle of the plane of the wheel relative to the vertical), making it possible to switch from indoor use (taking up a minimum of space, in order to pass through standard 80-cm wide doors) to outdoor or “sport” use (camber adjusted for better stability). However, handling remains complicated and no solution is provided with regard to vibrations or the negotiation of obstacles. A slightly lower risk of overturning is obtained, but only at the cost of an adjustment that is difficult for the user to perform.
To give a structural example, all of the current non-collapsible wheelchairs comprise a single rigid crossbar that supports the wheels of large diameter, and all the chairs are based on this immutable concept.
As for the current small front wheels, one skilled in the art knows that it is not unusual to see out-of-round wear on the joint, which can result in the breakage of the piece, caused by the mechanical stresses sustained by the fork, which stresses are even greater when they act on wheels of small diameter.
There is the known patent EP 0 384 499, according to which the central suspension comprises a funicular quadrilateral with an articulated parallelogram in order to reduce the risk of overturning backward during an effort. This document does not solve the same problem as the present invention, and its technical solution is unrelated. However, this document clearly illustrates the multitude of problems, discomforts and even risks that the user must face.
It seems that the profession is satisfied with this state of things, the vast majority of clients by definition not having much control over their choice, while cost considerations, which are important, have prevailed against any major innovation.
Also known through the document U.S. Pat. No. 5,180,025, which may be considered to describe the closest prior art, is an electric wheelchair in which the wheels are mounted on a rudimentary suspension system. The latter is constituted by two helical springs, each pivotably joined to the frame of the chair by one end, and to a wheel support arm by the other end, said arm itself being joined by a pivot joint to a fixed piece of the frame.
Also known through the document U.S. Pat. No. 2,126,084 is a suspension system for motorized vehicles. It is an old document (1933), specifically devoted to suspensions for automobiles, and does not apply directly to wheelchairs. The main object pursued in this document is to provide a suspension system comprising a suspension for each wheel independent of the other wheels, housed in a tubular part of the body of the vehicle, which can be removed in one piece with the rest of the axle.
The value of the invention is that it approaches the problem from another angle, i.e., globally, and presents an overall technical solution that simultaneously eliminates a number of drawbacks.
The invention also provides many heretofore unknown advantages.
SUMMARY OF THE INVENTION
According to an essential concept of the invention, a chassis with a rigid center beam is used. Another essential concept of the invention resides in a rear suspension with a high clearance. For this reason, the rear suspension (AR) comprises an upper articulated triangle, a lower strut forming a countershaft to a shock absorber, with a wheel support pin.
The central beam can have any cross section, for example square or rectangular, depending on the cost. It would be preferable, however, for the beam to have an inverted trapezoidal cross section (small base at the bottom) in order to facilitate the collapsibility of the chair as described below, and to generate a negative cambering, also as described below.
Collapsibility is facilitated by a beam with an inverted trapezoidal cross section in that, by releasing a locking means that will not be described herein, the entire structure is lowered by gravity with a deformation of its geometry, the folding of the parts being facilitated by the trapezoidal shape, with suitable indentations cut into the edge of the beam in order to allow a complete folding.
Furthermore, a beam with an inverted trapezoidal cross section makes the triangle (
1
) (FIG.
3
and description below) shorter than the lower strut (
6
a
). Thus, during compression, for example during a turn, the lowering of the beam (vertical force represented by the arrow) translates (arrows) into a negative cambering of the wheel (i.e., the top part of the wheel is displaced inward); this results in better stability on the ground and hence better road-holding.
An adjustable shock absorber/telescopic spring is attached to the countershafts of the lower struts, and is mounted transversely inside the chassis beam. A helical shock absorber that allows a high clearance, or any other system allowing a high clearance, is entirely preferred.
The small front wheels (AV) are mounted on fixed or articulated struts with an original vibration filtering system, which is mounted on the support plate.
It must be noted that, in an entirely preferred way, the assembly of the parts of the suspensions AR and AV is mounted directly on the beam.
This assembly provides a level of comfort such that it becomes pos
Arent Fox Kintner Plotkin & Kahn
Johnson Brian L.
Yeagley Daniel
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