Motor vehicles – Power – Electric
Reexamination Certificate
1999-05-05
2001-03-27
Johnson, Brian L. (Department: 3618)
Motor vehicles
Power
Electric
C180S024020, C180S907000, C280S124110
Reexamination Certificate
active
06206119
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an electrical wheelchair, and in particular to an electrical wheelchair comprising a double-framed chassis for providing wheels thereof with excellent surface compliance when moving on an uneven road surface.
BACKGROUND OF THE INVENTION
Wheelchairs help those incapable to walk to move from one place to another. Conventionally, a wheelchair is driven manually by another person for moving the person seated thereon. This is generally inconvenient. An electrical wheelchair incorporates a power source, such as a battery-motor system, therein for assisting the movement of the wheelchair. The conventional wheelchairs are designed for moving on a substantially planar surface whereby turnover or other potential risk may occur when the wheelchair is moving on an uneven surface. Some of the conventional wheelchairs are equipped with tilting-resistant device for reducing the risk of tilting or turnover when moving on the uneven surface. Such tilting resistant devices are not good enough to effectively prevent the wheelchair for tilting and turnover. Some examples of the conventional wheelchairs are disclosed in U.S. Pat. Nos. 5,222,567 and 5,762,154.
Thus, it is desired to provide a wheelchair having a double-framed chassis which provides wheels thereof with excellent surface compliance when moving on an uneven surface thereby reducing the risk of turnover.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a wheelchair comprising a chassis having a double-framed configuration for providing wheels thereof with excellent surface compliance when moving on an uneven surface thereby reducing the risk of turnover. The wheelchair is capable of spinning about its own center on all kinds of surfaces, including raised surfaces, recessed surfaces and inclined surfaces.
To achieve the above object, in accordance with the present invention, there is provided an electrical wheelchair includes a chassis on which a seat is mounted. The chassis has a double-framed structure including a primary frame and a secondary frame pivotally connected to each other so as to be rotatable with respect to each other about a first rotational axis. Two driving wheels are mounted to the primary frame and independently driven by motors. The secondary frame has a front edge frontward extending beyond the primary frame with two front guide wheels mounted thereto whereby the front guide wheels are capable to orbit about the driving wheels by means of the pivotal connection between the primary and secondary frames as to provide the front guide wheels and the driving wheels with excellent surface compliance when the wheelchair is moving on an uneven surface.
REFERENCES:
patent: 1259064 (1918-03-01), Wolff
patent: 5413187 (1995-05-01), Kruse et al.
patent: 5435404 (1995-07-01), Garin, III
patent: 5697465 (1997-12-01), Kruse
patent: 5904214 (1999-05-01), Lin
patent: 5944131 (1999-08-01), Schaffner et al.
patent: 5964473 (1999-10-01), Degonda et al.
Johnson Brian L.
Luby Matthew
Pro-Techtor Inter-national Services
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