Patent Publication Number: US-6705824-B2

Title: Wheelchair lift device

Description:
This application is a continuation of U.S. patent application Ser. No. 09/675,318 filed on Sep. 29, 2000 and issued as U.S. Pat. No. 6,461,097 on Oct. 8, 2002. 
    
    
     FIELD OF INVENTION 
     The present invention is directed to a wheelchair lift apparatus of the type appended to and supported by a vehicle. The invention enables a wheelchair bound passenger at ground level to enter and be supported by a platform which, upon actuation, lifts the wheelchair bound passenger into a vehicle opening in a safe and efficient manner. A unique configuration is provided for actuating a bridge plate/roll stop which acts to prevent the wheelchair from rolling from the platform during the lift operation and further acts as a bridge between the platform and the vehicle interior once it is safe for the passenger to exit the platform and enter the vehicle. 
     BACKGROUND OF THE INVENTION 
     There has been a plethora of art dealing with the transport of wheelchair bound handicapped persons. Some of these devices are self supporting and can be rolled or otherwise pushed against a vehicle opening. Other such devices are appended to the bottom of a vehicle chassis while others are supported at or about the sidewall of the vehicle proximate the vehicle opening. All of these various configurations can benefit by the employment of the present invention. The invention, however, will be described by making reference to the latter embodiment for convenience. 
     Devices of this kind all must be provided with certain general design components dictated principally by the need to capture and lift the wheelchair bound passenger in a safe fashion as well as to enable the device to fold or somehow be made unobtrusive when not in use. Devices of this kind are generally shown in a series of patents assigned to Ricon Corp. typified by U.S. Pat. No. 5,605,431 issued on Feb. 25, 1997, the disclosure of which is incorporated by reference herein. 
     Specifically, wheelchair lift devices of the type disclosed in the &#39;431 patent include a mobile platform for receiving a wheelchair, a parallelogram mechanism for carrying the platform, a hydraulic system for actuating the platform through the parallelogram mechanism and a control unit to accomplish different motion patterns. The parallelogram structure enables the platform to proceed between ground level and a vehicle opening while maintaining a horizontal orientation for supporting the wheelchair bound passenger. This structure also provides for a storage orientation enabling the platform to swing in a ninety degree arc to assume a substantially vertical orientation once the passenger is on board to enable the vehicle to proceed in a normal fashion. 
     The parallelogram structure, in actuality, includes a pair of such structures, one being located on each side of the platform. Upon hydraulic actuation, these parallelogram structures can open or fold in order to carry out the motion patterns as noted above. There is also generally employed a second or lower parallelogram structure which is in sliding engagement with the upper parallelogram structure which facilitates stowage and other platform actuation orientations. Again, as noted, the details of these various structures are taught in a series of patents typified by U.S. Pat. No. 5,605,431. As such, no attempt will be made herein to discuss the details of these configurations. 
     In order to address certain safety concerns dictated not only by logic but also government mandate, it is necessary to provide roll stops on both the front and rear edges of the lift platform in order to prevent inadvertent egress from the platform during the lift operation. It is quite apparent from reviewing prior configurations of this kind that these roll stops must also be capable of rotating through an arc of travel to enable a wheelchair bound passenger to enter and exit the platform at appropriate locations. Specifically, the outer roll stop must rotate counterclockwise from a substantially vertical to substantially horizontal orientation acting as a ramp at ground level to enable a wheelchair bound passenger to be rolled on to the platform. At this instant, however, the inward roll stop must be at a substantially vertical orientation to prevent the wheelchair bound passenger from inadvertently traveling off of the platform and its inner edge. 
     As the hydraulics are actuated resulting in a lifting of the platform, both the outer and inner roll stops maintain a substantially vertical orientation thus capturing the wheelchair bound passenger on the platform. Once the platform reaches the vehicle entrance, the outer roll stop maintains its substantially vertical orientation but the inner roll stop must then travel in a clockwise arc to act as a bridge plate between the platform and the vehicle interior. This enables the wheelchair bound passenger to enter the vehicle for later transport. 
     The present invention has recognized a need to improve upon the way in which the inner roll stop is actuated to change its orientation as described. Specifically, devices of this kind have provided various cam and cable mechanisms to enable the inner roll stop to move from a blocking (vertical) orientation to a transporting (horizontal) orientation simultaneously as the wheelchair reaches the vehicle opening without human intervention. Likewise, as the wheelchair supporting platform is lowered from the vehicle opening towards ground level, this rather complex configuration of the prior art acts to simultaneously move the inner roll stop to a blocking orientation. This is an important feature for it does not require an operator to change the orientation of the roll stop for, to do so, may result in an inadvertent accident as the operator may on occasion forget to change the position of the inner roll stop due to mere human error or omission. 
     It is thus an object of the present invention to provide a mechanism for changing the orientation of an inner roll stop without the need for complex camming and cabling as is so often employed in the prior art. This and further objects of the present invention will be more readily apparent when considering the following disclosure and appended claims. 
     SUMMARY OF THE INVENTION 
     An advantage of the present invention involves an inner roll stop mechanism usable with a wheelchair lift having a platform movable between a raised position and a lowered position. The inner roll stop mechanism comprises a pivotal mechanism engaging said platform and a bridge plate for assuming a substantially horizontal orientation and a substantially vertical orientation as the platform proceeds between the raised position and the lowered position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 through 5 depict various plan views of the present invention during a cycle in which the present invention approaches a vehicle opening and is then stowed. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Wheelchair lift apparatus  10  includes lift platform  11  upon which a passenger bound wheelchair is intended to reside during normal operation of this device. The apparatus further generally includes a pair of handrails  12 , one on each side of platform  11  acting as safety barriers which can also include some type of safety belt or harness (not shown). 
     The lift apparatus of FIG. 1 is generally shown in an orientation as it approaches the opening of a vehicle. Support plate  17  is supported by the vehicle (not shown) whereby bottom plate  37  is bolted or otherwise fixedly joined to a vehicle support member for ridged attachment. 
     In operation, upper parallelogram  13  is actuated by hydraulic cylinder  18  which, in turn, is operated in conjunction with a suitable pump and electromechanical actuators (not shown), all of which is well known in this art. 
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     In the orientation shown in the various figures, upper parallelogram members  14 ,  15  and  16  together with support plate  17  maintain platform  11  in a substantially horizontal orientation as shown. In that this platform is intended to capture and maintain a wheelchair bound passenger, outer roll stop  19  which is spring biased in a substantially vertical orientation acts to prevent the wheelchair from inadvertently traveling over the outer edge of platform  11 . When platform  11  reaches ground level, plate  20  will contact the ground causing outer roll stop  19  into a substantially horizontal orientation acting as a ramp to enable entry and egress to and from platform  11 . 
     As noted, at the orientation shown in FIG. 1, inner roll stop  26  is illustrated as assuming a substantially vertical orientation to again prevent inadvertent progression of the wheelchair bound passenger from platform  11 . However, as platform  11  reaches the vehicle doorway, inner roll stop  26  assumes a substantially horizontal orientation (FIG. 2) without the need for complex camming or cabling as is commonly employed by the prior art. Specifically, in comparing FIGS. 1 and 2, lower parallelogram structure made up of elements  23 ,  24 ,  25  and  45  is impacted as contact block  22  enters into sliding engagement with the lower surface of parallelogram arm  15 . 
     As was the case with outer roll stop  19 , inner roll stop  26  is spring biased to assume a vertical orientation, the spring being configured within hinge  27 . It is noted that the lower parallelogram structure includes pivotable swing arm  45  which changes orientation as contact block  22  moves in response to a change in orientation of upper parallelogram arm  15 . Pivotable swing arm  45  includes saddle bolt  29  which is designed to travel within non-linear channel  28  configured within the side of inner bridge plate  26 . When assuming the horizontal orientation shown in FIG. 2, saddle bolt  29  is oriented to reside within curved section  28   a  of non-linear channel  28  which acts as a locking or securing means to maintain the horizontal orientation of inner bridge plate  26 . During this orientation, inner bridge plate  26  resides upon surface  31  as the floor to the transport vehicle. 
     FIG. 4 depicts the orientation of the present invention as it begins to fold for stowage. It is noted that hydraulic cylinder  18  further extends causing upper parallelogram structure  13  to approach a vertical orientation. Contact block  22  continues to slide along parallelogram arm  15  thus causing saddle bolt  29  of pivotable swing arm  45  to travel along non-linear channel  28 . This further causes inner bridge plate  26  to begin rising from surface  31  and approaches a perpendicular orientation to platform  11  which, itself, proceeds to assume the vertical orientation shown in FIG.  5 . 
     FIG. 5 shows the wheelchair lift apparatus of the present invention in a stowed configuration. Support arm  21  and platform  11  are substantially vertical as are the upper and lower arms  14  and  15  of upper parallelogram  13 . Hydraulic cylinder  18  is fully extended while the bridge plate (not shown) is tucked against support platform  11 . 
     What has now been depicted as the present invention is a simplified means of orienting inner bridge plate  26  through the use of a simple linkage and without the need for complex camming or cabling. As in prior configurations, inner bridge plate  26  can assume a blocking or bridging orientation and will do so automatically and without human intervention. Further, in light of the use of non-linear channel  28  and particularly curved section  28   a , bridge plate  26  will assume a substantially horizontal orientation against a biasing spring contained within hinge  27  until the orientation of platform  11  is substantially changed. 
     While various embodiments of the present invention have been described with reference to the drawings, these are not intended to limit the scope of the present invention, which is set forth in the appending claims. Various modifications of the above described embodiments can be made by those skilled in the art after browsing the specification of the subject application. These modifications are within the scope and true spirit of the present invention.