Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1998-11-19
2001-11-06
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Occupant propelled type
Reexamination Certificate
active
06311999
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a wheelchair with a closed, three-dimensional frame formed by a front transverse support, two lateral supports, which are arranged symmetrically in respect to the longitudinal center axis, and a rear transverse support, wherein the lateral supports have the shape of a letter L with an upright leg and a longitudinal leg arranged transversely in respect to the latter, wherein the front transverse support is arranged at foot height and the rear transverse support constitutes an axle tube for a pair of rear wheels.
BACKGROUND OF THE INVENTION
Conventional wheelchairs have two pairs of wheels, namely a rear pair of wheels with two large rear wheels, which can be manually driven, and a front pair of wheels, whose shafts can turn in a horizontal plane around a turning point. These wheelchairs are generally foldable and to this end have transverse supports made of two hingedly connected elements, each one of which is hinged on a longitudinal support. Therefore the width of this wheelchair is reduced when it is folded up. The disadvantage of these foldable wheelchairs lies in their lack of rigidity caused by the many hinged connections.
To remedy this disadvantage, it was attempted to produce wheelchairs with rigid and preferably closed frames. For example, a wheelchair of the type described at the outset was described in Swiss Patent Application 1547/97, whose frame is closed and therefore comparatively rigid. This frame consists of a front horizontal transverse support at the height of the feet of the user, a rear horizontal transverse support formed by an axle tube of the pair of rear wheels, and two L-shaped lateral supports, each one of which connects one end of the front transverse support with an end of the rear transverse support, and wherein each lateral support has an upright leg and a longitudinal leg. A front wheel arrangement with a single, centered front wheel, or two front wheels spaced apart from each other, is fastened on the front transverse support. This wheelchair has great rigidity and is easy to turn and maneuver, thanks to the front wheel arrangement which is generally placed in the central area of the front transverse support. It is mainly used as a sport wheel chair. The disadvantage of this wheelchair mainly lies in its poor tilting stability; it is therefore of less use for everyday use and is considered to be unusable by greatly handicapped and older users.
OBJECT AND SUMMARY OF THE INVENTION
It is therefore the object of the invention to improve the wheelchair mentioned at the outset in such a way that, with continued rigidity, it has a great degree of steadiness and therefore an improved lateral tilting stability, so that it can be also used without danger by seriously handicapped and older handicapped persons.
The objects according to the invention are achieved by the provision of a wheelchair with a closed three-dimensional strutless frame, the frame consisting of: a transverse axle tube for a pair of rear wheels, two lateral portions extending forwardly from the axle tube, each the lateral portion being unitary and having the shape of a reverse letter L, the two lateral portions being arranged symmetrically with respect to the longitudinal central axis of the wheelchair, and each L-shaped lateral portion consisting essentially of a generally longitudinally extending upper leg and a generally vertically extending lower leg at the front of the wheelchair, the upper leg having a rear end connected to the axle tube and a front end, and the lower leg having an upper end connected to the front end of the upper leg and a bottom end, a lower transverse horizontal front portion at a height to support a user's feet having two side ends respectively connected to bottom ends of the lower legs of the lateral portions, and front wheel supports, each of which is attached on the lower leg of a respective one of the lateral portions.
The same as the previously known wheelchair, the novel wheelchair has a closed frame, but is considerably more steady and laterally more stable against tilting thanks to the front wheels, which are fastened at a great distance from each other on the front wheel supports.
A further advantage of the novel wheelchair resides in that it provides the option of arranging the front wheel support relatively high above the ground, so that front wheels of relatively large diameter can be used, because of which traveling over uneven ground and overcoming stairs is made easier.
It is possible to attach front wheels of various diameters, depending on the height at which the front wheels are fastened.
Weight savings at the front are achieved by a rigidly welded front wheel suspension, because of which the wheelchair is easier to maneuver.
Depending on the requirements of the user, the front wheel supports can be fastened on the upright legs of the lateral supports in various positions in relation to the longitudinal center plane of the wheelchair. The front wheel supports can extend parallel or obliquely, respectively toward the front or rear, but also laterally transversely in relation to the longitudinal center plane of the wheelchair, wherein each one of these arrangements has certain advantages, but also certain disadvantages. The farther the front wheels extend transversely, the greater the steadiness and lateral tilting stability. Front wheels extending far forward also increase steadiness. But a disadvantage of these arrangements is the reduced ease of turning and the danger that such projecting front wheel supports touch objects in the vicinity of the wheelchair and therefore constitute a hindrance to the movement of the wheelchair. These disadvantages can be avoided when the front wheel supports are oriented parallel in respect to the longitudinal center plane or obliquely in respect to it. With forward oriented front wheel supports, the base generally is larger than with backward oriented front wheel supports, and it is in addition possible to protect the area of the feet of the user from injuries, if the front wheels constitute the farthest forward and possibly the farther lateral portion of the wheelchair. But coupled with this are a reduction in turning ease and greater difficulties in manipulation because of the danger of colliding with the front wheels. With front wheel supports oriented forward and slightly toward the longitudinal center plane, a very large base is still obtained, as well as satisfactory ease of turning, and the collision of the front wheels with the vicinity is prevented, but such front wheels can be unsatisfactory for the arrangement of the footrest. Front wheel supports, which are oriented slightly backward and inward, have proven themselves, so that with a still sufficient steadiness satisfactory turning ease is obtained and front wheel collisions are avoided.
The front wheel supports can also be fastened adjustably in respect to their position in relation to the longitudinal center plane of the wheelchair. However, in this case the fastening should be free of play and should not loosen during use. But the weight of the wheelchair becomes greater because of this and it becomes less easy to turn, because the additional weight is situated at a comparatively large distance from the center of gravity of the wheelchair.
If the front wheels are fastened in a height-adjustable manner on the upright legs of the lateral supports, there is also the option of mounting front wheels of various diameters for the adaptation to changing requirements.
The front transverse support can be produced integrally with the two lateral supports. However, it has been shown to be advantageous to design the front transverse support in such a way that it has a neck on both sides, which extends in the direction of the adjoining upright legs of the lateral support, by means of which it is height-adjustably fastened on this upright leg. height adjustability of the front transverse support is required in particular when a footrest is formed on it. But the footrest can also be fastened to the uprigh
Browdy and Neimark
Johnson Brian L.
Kueschall Design AG
Winner Tony
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