Material or article handling – Self-loading or unloading vehicles – Loading or unloading by other carrier or mover means – and...
Reexamination Certificate
2001-08-27
2003-11-18
Bratlie, Steven A. (Department: 3652)
Material or article handling
Self-loading or unloading vehicles
Loading or unloading by other carrier or mover means, and...
C414S921000, C414S550000
Reexamination Certificate
active
06648579
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a platform lift, especially for transferring wheelchair occupants between a passenger compartment and the ground. The inventive lift has a particular configuration for parallelogram-linked support arms driven using a drive cylinder, and includes safety gates that are mechanically linked to operation of the lift.
In a preferred arrangement the lift mechanism has movable parts successively connected on different axes to permit rotation about the respective axes for stowing, deploying and moving a platform that supports the load, such as a wheelchair. The lift is apt for use in a van, bus or light truck.
The platform for the wheelchair or other load is pivotable on a horizontal axis between a horizontal supporting orientation and a vertical stowing orientation. In a preferred arrangement, the horizontal axis on which the platform pivots is in turn mounted so as to pivot on a vertical axis at one lateral side of the door, whereby the platform when oriented in a vertical position can be opened and closed like a door or gate panel.
The horizontal axis hinging is between the platform and a base plate. At one side of the doorway the baseplate is carried on a heavy duty vertical hinge axis coupling or journal post, and at the opposite side a protruding end of the baseplate is fixed with a clamping latch.
The horizontal axis pivoting between supporting and stowed positions and the vertical axis gate-like pivoting are between the platform part and two vertical standards that extend vertically and are disposed at the lateral opposite sides of the doorway. The vertical standards are mounted by a parallelogram linkage to vertical posts that are rigidly fixed to the vehicle at the lateral sides of the doorway.
The lift has at least three distinct modes of movement. In one mode, the parallelogram linkage holds the platform in a horizontal orientation as the platform is raised or lowered between ground level and the level of the vehicle passenger compartment. Movable gates at the platform edges permit the wheelchair to roll onto and off of the platform at either level and block roll-off when the wheelchair is between levels.
In a second mode, the platform is pivotable on a horizontal axis relative to the vertical standards. The platform is pivoted on the horizontal axis to raise the platform from its horizontal wheelchair-carrying orientation to a vertical stowed orientation.
A third mode is gate-like hinging to block or clear the doorway. With the platform vertical, and preferably with the vertical standards retracted via the parallelogram linkage, the platform and its base plate can be detached from one vertical standard to hinge on the vertical axis defined by the journal post at the other vertical standard, so as to hinge open and closed like a door or gate.
According to an inventive aspect, movable doorway plane barriers are linked between the relatively movable parts of the lift and are structured for automatic deployment when the platform is in a position other than coplanar with the passenger compartment. The barriers are linked with a sort of lost motion engagement rather than a positive engagement so that the barriers are compliant should they deploy onto an obstruction such as a person occupying the space. The barrier member is mechanically coupled to the movable parts of the lift by a mechanism having a lost motion component. The barrier member is deployed into position obstructing the doorway immediately upon displacement of the lift from a fully retracted position, wherein the barrier member is against a stop. On further displacement of the lift, the lost motion allows the barrier member to remain stationary as the lift is lowered. Moreover, the lost motion can be compliant if the barrier member is arrested short of its stop, for example if the barrier member is deployed against a person or an object in the doorway.
The movable vertical standards are connected to the fixed posts by a set of parallelogram arms. A drive means is provided such as a drive cylinder that is controllably extensible and retractable, e.g., a hydraulic or pneumatic cylinder, linear actuator motor or the like, for expanding or contracting the parallelogram linkage. According to an inventive aspect, the drive cylinder is mounted so as to have one or both of its opposite ends attached at rotational pivot points spaced from the pivot points that attach the parallelogram members. This arrangement has a number of advantages including the ability to orient the cylinder for urging in the vertical standards to nest of couple into the fixed posts, and a wear resistance aspect.
When nested together, the movable vertical standards engage with the fixed posts at engagement couplings, locking to provide a stable structure from which the platform can hinge on the journal post, without sagging.
A particularly robust and secure clamped latch arrangement is provided between the platform and the adjacent movable vertical standard on the side opposite from the vertical hinge. The clamped latch comprises a leveraged operator that fixes a protruding bar adjacent to the horizontal pivot axis of the platform, received in a structurally supportive receptacle coupled to the vertical movable frame. The journal post and clamping latch bear the concentrated load of a wheel chair on the platform when cantilevered outwardly.
PRIOR ART
Platform lifts with parallelogram linkage supports are disclosed, for example, in U.S. Pat. No. 4,456,421—Robson; U.S. Pat. No. 4,534,450—Savaria; U.S. Pat. No. 4,984,955—McCullough; U.S. Pat. No. 4,808,056—Oshima; U.S. Pat. No. 5,234,311—Loduha, Jr. et al.; U.S. Pat. No. 5,261,779—Goodrich; and, U.S. Pat. No. 5,806,632—Budd et al., which are hereby incorporated. These patents disclose a number of alternative arrangements in which a load platform is carried by a movable member of a linkage structure having paired opposite members. Typically the opposite members are straight bars coupled to hinge or pivot at points near their ends.
A proximal one of the members is defined by or is rigidly attached to a portion of a vehicle at a doorway. The parallelogram linkage expands and contracts to move a load platform carried by a distal one of the members, back and forth between the ground level and the vehicle passenger compartment level. The members of the linkage need not be straight or elongated members. The pivots need not be located at the ends of the members. However, the members maintain a rigid space between hinge points that define the apices of a parallelogram. The parallelogram can expand into a rectangle where the lines connecting the pivot points are oriented at right angles at each of the four pivot points. The rectangle also can contract or collapse such that each pair of opposite angles becomes acute, with the other pair being obtuse. Assuming that there are no other impediments, the rectangle can collapse in either direction from a right angle. That is, either of the opposite pairs can become acute or obtuse.
A parallelogram linkage is advantageous in a load platform lift, for example for a wheelchair, because the linkage ensures that the opposite members of the linkage remain parallel. Thus if a proximal linkage member is vertical, for example being fixed at a vertical orientation in a vehicle doorway, the opposite member will also be vertical, at all positions of the parallelogram linkage. A load carrying platform can be arranged to be held horizontal on a linkage member that is opposite from the stationary linkage member of the parallelogram, and will remain horizontal as the lift moves.
Expansion and contraction of the parallelogram causes the lift platform to be raised and lowered. Typically, expansion from an upwardly collapsed position moves the platform outward and down. The linkage passes through an intermediate position at which the linkages are at right angles. Further downward movement of the platform carries the linkage into a downward and inward.
Driving forces can be coupled to the members of the parallelogram linkage in various ways
Bratlie Steven A.
Duane Morris LLP
LandOfFree
Platform lift does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Platform lift, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Platform lift will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3146133