Material or article handling – Self-loading or unloading vehicles – Loading or unloading by other carrier or mover means – and...
Reexamination Certificate
1997-08-27
2001-01-30
Werner, Frank E. (Department: 3652)
Material or article handling
Self-loading or unloading vehicles
Loading or unloading by other carrier or mover means, and...
C414S917000, C414S921000, C414S543000
Reexamination Certificate
active
06179546
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to lifts. More particularly, it relates to wheel chair lifts for vehicles.
Lift mechanisms which enable large and/or unwieldy articles to be transferred into and out of vehicles have been in existence for some time.
A number of lifts have been adapted for passenger vehicles to provide access for people with handicaps. Most of the prior art wheelchair lifts which are stowable on the exterior of vehicles require relatively extensive track systems or support structures on the undercarriage of the vehicles. These extensive tracks and support systems add weight to the vehicle and take up substantial amounts of space which limits their usage to certain full size vans or other large vehicles.
The prior art wheelchair lifts, which do not utilize the track systems or extensive support structures will typically provide attachment points that are quite close to each other on the wheelchair platform. This can cause stability problems and extreme stress in the areas of attachment between the platform and the lifting links. Attempts to increase the stability and rigidity such as by providing reinforcing structure on the platform will necessarily increase the weight which will be raised and lowered requiring more power and thus stronger and heavier structures for supporting the up and down drive lifting means. Examples of prior art lifts follows.
U.S. Pat. No. 3,263,835 to Lugash discloses a lift that is rotatably attached to an undercarriage of a truck. The lift comprises a platform which is raised or lowered by two sets of rotatable “pantographic” arms located at the sides of the platform and which are concurrently actuated by a hydraulic cylinder. This lift takes up a substantial amount of vertical space and thus would be difficult to use as a wheelchair lift mounted below the undercarriage on modern mini-vans.
U.S. Pat. No. 4,711,613 to Fretwell discloses a wheelchair lift rotatably attached to an undercarriage of a vehicle. The lift comprises a platform which is raised or lowered by a pair of adjacent parallel links located at one side of the platform. Power to the parallel links is provided by a hydraulic cylinder one end of which is attached to one of the parallel links, the other end of which is attached to the rotational support assembly. The platform is attached to the links at a centrally positioned region at two points quite close to each other on the side of the platform. This may cause operating difficulty or instability, particularly when the weight of the wheelchair is forward or rearward on the platform.
Another lift which is rotatably attached to a vehicle is disclosed in U.S. Pat. No. 4,026,387 to Abreu. In Abreu, a platform is attached at one corner to a dual purpose mechanism which is attached to an exterior side of a vehicle adjacent a door opening. The dual purpose mechanism raises and lowers the platform by means of powered telescoping shafts which serve to raise and lower the platform. The dual purpose mechanism also permits the platform to be rotated between operative and storage position. When the platform is in its stored position, the top surface of the platform abuts the undercarriage of the vehicle and frictionally retains the lift in its storage position. Again, the closely spaced attachment points of the lift mechanism to the platform can create operating and stability problems particularly when the weight of the wheelchair is distally positioned on the platform.
Another type of lift is disclosed in U.S. Pat. No. 4,134,504 to Salas. In Salas, a lift is attached to an undercarriage of a vehicle and is horizontally extended and retracted between operative and storage positions by a somewhat complex cable system. The lift comprises a platform which is raised or lowered by two sets of parallel arms located at the sides of the platform, and which are concurrently actuated by a hydraulic cylinder. Only one of the parallel arms of each set is powered.
Yet another type of lift is disclosed in U.S. Pat. No. 5,556,250 to Fretwell. The Fretwell '250 is similar to the Salas lift mechanism in that Fretwell '250 provides two sets of parallel arms located at the sides of a platform, the parallel arms are concurrently actuated by a hydraulic cylinder, and the lift mechanism is linearly extended and retracted between operative and storage positions by a complex gear and chain driven track system. Fretwell '250 also discloses an enclosure, attachable to the undercarriage of a vehicle into which the lift mechanism is positioned for storage.
SUMMARY OF THE INVENTION
The present invention provides a robust, highly stable and compact wheelchair lift suitable for placement on a variety of vehicles such as vans and mini-vans. The lift has an elongate horizontal support member that is pivotally attached to a post on the underside of a vehicle. The horizontal support member supports the lifting mechanism and the wheelchair platform and is powered to swing the platform and lifting mechanism between a use position and a storage position. The lifting mechanism uses a pair of connecting links spaced lengthwise on the support member and connecting to the wheelchair platform in a four bar linkage arrangement generally in the form of a parallelogram. Both connecting links are rotated by bell cranks both of which are powered by the same hydraulic cylinder.
A feature and advantage of the invention is that the horizontal support member extends along a substantial length of the platform and the connecting links are spaced lengthwise on the platform to provide a robust, stable, and compact design.
A further object of the invention is to utilize a four bar linkage arrangement in which the two pivot points on the wheelchair platform are substantially in horizontal alignment and the two pivot points on the horizontal support member are in substantial horizontal alignment. Moreover, when the platform is in its storage position all of the pivot points are in substantial horizontal alignment to facilitate a vertically compact configuration.
An object of the present invention is to provide a lift which can be easily attached to an undercarriage of a vehicle in its own enclosure.
Another object of the present invention is to provide a lift which can be easily moved between storage and operative positions.
Another object of the present invention is to provide a platform which can be easily raised and lowered through a large range of motion.
Another object of the present invention is to provide a lift mechanism which is easily assembled and maintained.
Another object of the present invention is to provide a lift mechanism which is compact and thus highly versatile and may be installed in a wide range of vehicle types.
Yet another object of the present invention is to provide an enclosure into which the lift is housed to protect the lift from the elements.
These and other objects of the present invention will be apparent from a reading of the specification and claims.
REFERENCES:
patent: 3263835 (1966-08-01), Lugash
patent: 4026387 (1977-05-01), Abreu
patent: 4134504 (1979-01-01), Salas et al.
patent: 4711613 (1987-12-01), Fretwell
patent: 4909700 (1990-03-01), Fontecchio et al.
patent: 4958979 (1990-09-01), Svensson
patent: 5158419 (1992-10-01), Kempf et al.
patent: 5253973 (1993-10-01), Fretwell
patent: 5375962 (1994-12-01), Kempf
patent: 5447317 (1995-09-01), Gehlsen et al.
patent: 5556250 (1996-09-01), Fretwell et al.
patent: 5613825 (1997-03-01), Dorn
Christensen Douglas J.
RC Sales and Manufacturing
Werner Frank E.
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