MXPA98009921A - Stowed platform wheelchair lifter - Google Patents

Abstract

A wheelchair platform free fall control system having a tension means biasing together the long (20, 20') and short arms (24, 24') of a lever arm assembly (14, 14') that keeps the lever arm slide block (42, 42') in contact with a lifting arm (30, 30') during gravity-down deployment of the platform (12) from an over-vertical stowed position to a horizontal transfer position. The tension means may be one or more springs (60, 60') and a compression means may be a gas spring (52). The forces are preselected to provide an over-vertical assist while keeping the slide block (42, 42') in contact with an arm (20, 20') of the lifting assembly (14, 14').

Description

WHEELCHAIR ELEVATOR WITH HIDDEN PLATFORM DESCRIPTION CROSS REFERENCE TO RELATED REQUEST This application describes and claims as an International Application the matter in question described in the United States Provisional Application, Serial Number 60 / 041,709, filed on March 26, 1997 and described in the United States Regular Application, Issue Number. Series 08 / 843,497 filed on April 16, 1997. The priority of the filing dates of each of the applications for those applications is hereby claimed, and the description of said applications are hereby incorporated by reference.

TECHNICAL FIELD This application relates to wheelchair lifts having concealable platforms, and more particularly to double parallelogram type lifts which employs an articulated lever assembly having a sliding block for levering the platform from an orientation of horizontal transfer, or a hidden position on the vertical. A spring-assisted system comprising a gas spring and at least one articulated lever assembly closing spring is provided to assist the unfolding (unfolding) of the platform in a downward gravity mode from a hidden position on the vertical without uncontrolled panel movement of the platform and sudden free fall in an orientation closer to the horizontal.

PREVIOUS TECHNIQUE: Parallelogram-type wheelchair lifts are offered by various manufacturers, including The Braun Corporation of Winamac, IN in their L900 series of elevators, as shown in their United States Patent 5,261,779 and by Ricon Corporation of Pacoima , CA in its S series of elevators as shown in U.S. Patent 4,534,450 and U.S. Exp. 31,178. These elevators employ various mechanisms to cause the platform to move accurately upward from the horizontal transfer level to a hidden vertical or vertical position. One system involves the use of an articulated lever assembly comprising a pair of arms of different length pivotally connected to each other at one end, and pivotally connected at their other ends respectively to: a) the vertical boom, and b) the inner end of the platform. As the hydraulic ram is actuated in the lift assembly, raising the platform from ground level to the transfer level, a sliding block, pivotally secured to the common center of the two arms, comes into contact with the lower arm of the parallelogram. As the elevation continues and the end link approaches the lower arm, the longer lower arm of the lever assembly is pushed downward. This in turn causes the outer end of the platform to turn up to the hidden position. Occasionally there is a loss of hydraulic fluid pressure and the platform may fall down, generally parallel to the hidden position. When mounted inside a vehicle, for example the side or rear door of a truck or truck, the bottom of the platform (inner end) may fall away from the posts on which the parallelogram arms are mounted and interfere with the opening of the vehicle door.

These types of lifts also involve the use of individual-action hydraulic cylinders that pull (Braun 5,261,779) or push (Ricon Re 31,178) to lift and hide the platform, while allowing gravity to carry the platform down from the vertical hidden position by releasing the hydraulic pressure on the active side of the hydraulic cylinder that drives the arms of the parallelogram: however, the preferred position of the platform is on the vertical to secure it during the movement of the vehicle. Accordingly, the Braun L900 series uses a gas spring mounted on the lower channel arm of each of the parallelograms to push the parallelograms outward., causing the platform to move outward over the vertical position to a point where gravity can assume the direction for further deployment of the platform. In some cases, for example, when the vehicle may not be level, where the friction forces can accumulate in the platform pivot of the external link (lifting arm), or where the two parallelogram arms meet or are not synchronized, etc. ., the platform can move outward from the hidden position, although parallel to it, instead of rotating from its lower end gently downwards to the horizontal transfer level deployed. The platform can then turn in a sudden arcing movement (free fall) when the parallelogram moves far enough outside and below so gravity pulls the platform down as well. This movement can be sudden and embarrassing to the observers, particularly those outside the vehicle, although it is not dangerous as long as there is no one on the platform, unless a person outside the vehicle remains where it should not be, that is, at the usual and intended trajectory of the descending elevator. One proposed solution is the use of a bolt-and-groove assembly, such as that used in the L200 Braun series telescopic arm lifter since 1978 (for example, the cutting and bearing assembly on the Braun Model L211U), or the bolt and slot assembly in the seat block of Saulier Patent 5,605,431 by Ricon (as shown in Figs 13-15 thereof). Both were releasably intertranding the platform to the elevator assembly during the gravity descending phase of the platform deployment from the vertical to the horizontal transfer level in a sudden pivotal free fall. However, Braun's cutting edge / bearing system, while mechanically protruding, is relatively expensive. The Ricon parallelogram pin / slot block seat assembly, while cheap, is prone to wear and tear. The lower arm bolt / groove bolt assembly by Ricon introduces another pair of tie points into the separate parallelogram arms that must be kept in sync. This becomes increasingly difficult since the two separate elevating parallelograms can not move in the same way during long-term use cycles due to wear on the hydraulic pistons or bars, or the accumulation of friction in the pivots, or the development of sediment or rubber in the hydraulic lines, or torsion twist when the vehicle is not level, or similar. Consequently, the lower arm bolt / groove that interlocked in the lower surface of the lower parallelogram arms is not necessarily the best or the only solution to prevent occasional platform free fall. Another solution has been to provide torsion springs on two or more diagonally opposed pivots of the parallelogram to assist in the movement of the parallelogram and the platform out of the hidden position on the vertical, or a torsion spring on the pivot pin of the block ( sliding) of seat. However, such springs can weaken or break over time as they are stressed, and are relatively difficult to replace.

BRIEF DESCRIPTION, OBJECTS AND ADVANTAGES OF THE INVENTION Among the objects of the invention is to provide an inexpensive system to promote the movement of the lever articulated with the paralyogram during deployment in the gravity descending mode of the vertical hidden position to the horizontal transfer position to prevent the platform from falling freely. Other objects and advantages will be apparent from the descriptions, drawings and claims of this invention. The invention comprises providing at least one tension type spring that connects diagonally between the two arms of the articulated lever adjacent the sliding block, or between an arm and the lifting arm. This joins or holds the two arms together, forcing the sliding block up against the lower arm of the parallelogram. In addition, the arm of the parallelogram is aided during deployment by the use of a gas spring to bring the platform back and out (towards the external position) from the position on the vertical. Since this gas spring is under compression, if the hydraulic components lose pressure, the gas spring will tend to cause the platform to fall out of the vertical position. In the case of the bolt / slot type assembly such a fall will also cause the platform to rotate, and the upper (outer end) of the platform may interfere and / or significantly obstruct the truck door, in contrast, with the system of articulated arm spring of this invention, those springs prevent the fall of the platform from the loss of hydraulic pressure or the induced fall when the vehicle turns to the left or tilts down to the right. Accordingly, it is a more important aspect of the invention to balance the two spring forces, the net internal tension force of the diagonal articulated arm spring (s) against the external compression force of the arm auxiliary gas spring of the parallelogram.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by reference to the drawings in which: Fig. 1 is an isometric view of a typical Braun parallelogram elevator where the hydraulic cylinder is of the pull type (retraction) and is diagonally down at the position of floor of the platform, and illustrates the gas spring support; Fig. 2 is a side elevational view of a typical parallelogram elevator of the Ricon type showing three basic positions, the lower floor position in dotted lines, the transfer position or vehicle entry level in solid lines, and the hidden position on the vertical, also in dotted lines; Fig. 3 shows in lateral elevation the diagonal spring of the invention that expands and connects the two arms of the articulated lever assembly; Fig. 4 shows in isometric view of a typical parallelogram pivot spring of the prior art which replaces the present invention.

DETAILED DESCRIPTION OF THE BEST WAY TO CARRY OUT THE I NVENTION: The following detailed description illustrates the invention by way of example, not in the form of limitation of the principles of the invention. This description will clearly allow someone with ordinary skill in the art to make and use the invention, and describe various embodiments, adaptations, variations, alternatives and uses of the invention, including what is currently considered to be the best way to carry it. out the invention. Fig. 1 shows a parallelogram elevator of the Braun 10 type comprising the platform assembly 12, paired parallelogram arm lifter assemblies 14, 14 ', articulated lever assemblies 16, 16' and the hydraulic pump / control assembly 18 as mounted in the vehicle V, for example in a side door opening, D. The elevating assembly parallelogram comprises its top links 20, 20 ', lower links 22, 22 ', subsequent links 24, 24' (located but not visible on posts 26, 26 '), and front links 28, 28'. The lower front link extensions 30, 30 'are the lift arms to which the platform assembly 12 is pivoted at 32 adjacent to the inner end, but external to it a sufficient distance to provide a lever arm by the spacing between the pivot 32 and the lower pivot of articulated plate arm 34, 34 '. The fixing plate is 36, and the hydraulic lifting cylinders are 38, 38 '. The articulated lever arm assembly 16, 16 'comprises the longer press arm 40, 40', the pivoting slide block (seat block) 42, 42 ', and the short top snap arm 44, 44'. The elevator is shown at the floor level with the sliding block 42 decoupled from the sliding contact with the lower side 50, 50 'of the lower parallelogram arm 22, 22' (bottom link). The gas spring support 52, 52 'is secured at the outer bar end 54 to the interior of the lower arm 22 and at the end of the internal cylinder 56 to the rear link 24. The portions of the lower arm and the pole cover are separated to show the ends and the assurance points. One embodiment of the diagonal lever arm closing springs of this invention comprises pairs of tension springs 60, 60 'for each of the lever arm assemblies, although they may be more or less springs. Preferably, at least one spring is used, either internally or externally of the lever arm assembly channel members. In the Ricon pin / slot assembly, a reverse type torsion spring or compressor (having ends captured in the tubes 76, 76 ', see Fig. 3) is used in each of the pivots 62, 62' for force together the two arms of the articulated lever assembly. The closing spring of the present invention can be used with or without such torsional pivot pin springs, preferably without them, to eliminate the torsional spring failure. Therefore, in the invention, the springs 60, 60 'force the two arms together, which is referred to herein as closing springs. Fig. 2 shows a Ricon-type elevator in the ground position G, the transfer position T, and the hidden position S. A bolt or button can be used in the face of the sliding block 42 (not shown, but see Figs. 15 of 5, 605,431 incorporated by reference herein to the extent necessary) to cooperate with a keyhole slot (not shown) on the underside 50 of the lower arm 22. The pin / slot assembly can be used in conjunction with the springs 60 and / or a gas spring 52 of this invention, but such a bolt / slot assembly is not required. The spring pairs 60 are showing link arms 40 and 44, although they can be joined between an arm 40 or 44 and the lift arm 30. Fig. 3 illustrates an enlarged view of the closure spring assembly, in this case a pair of springs 60, comprised of the external spring 60a and the internal spring 60b (one on each side of the channels U of the arms 40, 44 as shown). These springs are tension type springs, preferably inverse coils, which are mounted in holes 70 punched in each pair of arms.

Note that the arrangement of holes 70a, b, c in each of the arms 40, 44. This allows the adjustment of tension. Observe holes 90a-90e in the boom extension. These can serve as anchoring points for springs extending from, say, 70a 'to 90b as shown by arrow D, or 71 a, b, c to 90e as shown by arrow C, for example. In the Ricon pin / slot system a torsion spring 72 is used with ends captured in the tubes 76, 76 '. That tension spring is preferably eliminated in the present invention since it is prone to failure, it can apply only limited force, and during its life the force changes as it is exhausted. The two arms 40, 40 'are pivoted at one end, commonly with the sliding block 42, all rotatably supported on the pivot pin 62. The face of the sliding block preferably employs hardened low friction plastic buttons 74, 74', to reduce wear, such as ultra high molecular weight polyethylene. The gas spring 52 (only the enclosed spring-bar end is shown) is pivotally secured at 54 inside the bottom of the U-shaped channel member forming the lower arm 22. The position shown is only approximate and schematic. When a keyhole slot with a pin is used, the connection point of the gas spring may be in another location above or below the slot, for example, at or near point A or point B (preferable), depending on the amount of external lever force required to provide support to the gas spring to overcome the resulting moment of the platform on the vertical. This is a function of the platform hub, the frictional resistance of the pivots or bearings, and the speed of extraction of the hydraulic fluid to the opening of the hydraulic valve for the downward movement by gravity, deployed. The tension imparted by the springs 60 provides a more controlled, uniform unfolding without interfering with the rate of deployment (descent) down to approximately the transition level. Fig. 3 shows the contact of the sliding block 42 approximately at that level. It should be noted that the width between the side walls of the channel member forming the lift arm 30 is sufficient to provide clearance for the springs 60. That is, when the platform is completely hidden (position S in Fig. 2) the springs and arms 40, 44 are completely separated within arm 30 without interference. Fig. 4 shows a conventional pivot pin torsion spring 72 mounted on the lower end 22 about the pivot pin 80. The rear link is not shown, but the pivot pin assembly also passes through the walls thereof. This type of torsion spring is eliminated in this invention by balancing the spring forces of the gas spring 52 (outwards) and the diagonal closing spring (s) 60 (inwards). This is the type of spring used in the Ricon pin / slot arrangement (see Figure 3). It is evident that since the springs are over-stretched, they fatigue and / or fail. Being "hidden" in the elevator assembly, they are expensive to replace. In contrast, external closure springs 60 are easy to retrofit and replace.

I NDUSTRIAL APPLICATION It is evident that the closing spring system of this invention (alone or in combination with the gas spring (preferable), or a bolt / slot assembly (preferable), or the sliding block inverse torsional spring), provides a solution simple, inexpensive, easy to replace, repair and retrofit for free fall of the platform, without introducing the problems of failure / fatigue of the torsion spring of the pivot pin or bolt / slot union and wear problems, that provide better deployment control. It should be understood that various modifications may be made within the scope of this invention by someone skilled in the art without departing from the spirit of the same. For example, the gas spring and the closing spring system can be applied to a side bearing and edge assembly, to elevators of different types to double parallelogram elevators, and the like. The gas spring may be external to the paraielog lift, as for example in the case of the Ricon-type elevator where the orientation of the lift arm is inverted, so it does not provide the internal clearance for the gas spring. The diagonally closing springs can be replaced with hydraulic cylinders, reverse gas springs (tension instead of compression type), chain or cable drive links, or the like. Likewise, the gas spring can be hydraulic, pneumatic or a linear actuator if this is desired to be an active element instead of a stored energy element. While the hidden platform assembly is referred to herein as a lever arm system, it may also be called a second smaller parallelogram system to distinguish it from the elevating parallelogram assemblies. As an alternative embodiment, the closing springs may extend between any arm 40, 40 'of the articulated lever assembly and the lower extension arm 30, or three pairs of springs, generally placed in a triangle between the arm 44, the arm, may be used. vertical 30 and arm 40. Also, the bolt, button or bearing of the bolt / slot assembly can be replaced by an electromagnetic assembly. Therefore, it is desired that the invention be defined by the scope of the appended claims in view of the specification as broadly as the prior art allows.

Claims (17)

REVIVAL D ICAC I ON

1 . A system for controlling free-wheeling movement of a wheelchair lift platform from the concealed position towards the transfer position in an elevator having a lever arm system, comprising in operative combination; a) a lifting parallelogram having an upper arm, a lower arm, an internal link and an external link, the external link including a generally vertical lifting arm having a lower end to which the platform is pivotally secured; b) a lever arm assembly having a first upper short arm secured pivotally at a first end to said lifting arm and at an end opposite an upper end of a second longer arm, and a pivotally mounted sliding block coaxially with the pivot connection of said first and second arms, the second arm having a lower end pivotally mounted to the lifting platform within the pivot connection of said lifting arm to said platform; c) tension means for deflecting said first and second arms of the lever arm assembly to drive the sliding block against the lower surface of the lower arm of the elevating parallelogram so as to move downwardly from said lifting platform from the positions vertical or on the vertical to the substantially horizontal, the lifting platform is controlled to reduce or eliminate the external fall generally parallel to the hidden position and hence in free fall, although instead of pivoting in an arched movement with the arm sliding block of lever in contact with the lower link parallelogram arm.

2. A free fall control system as in claim 1 including: a) compressive force means to assist the outward movement of said lifting parallelogram from a vertical or vertical position during a downward gravity mode; and b) the compressive force means are mounted between a back link and an arm link of the elevating parallelogram and urges the platform out from a hidden position on the vertical to help overcome the resting moment of the platform mass.

3. A free fall control system as in claim 1, wherein the sliding block pivot does not include a torsion spring.

4. A freefall control system as in claim 1, wherein the lift parallelogram pivots do not include torsion springs.

5. A free fall control system as in claim 2, wherein the sliding block pivot does not include a torsion spring.

6. A free fall control system as in claim 2, wherein the lifting parallelogram pivots do not include torsion springs.

7. A free fall control system as in claim 1, wherein the tension means is at least one spring.

8. A freefall control system as in claim 7, wherein said spring is mounted at one end of the upper short arm and at its other end to the longer lower arm.

9. A free fall control system as in claim 2, wherein the compression means is a gas spring.

10. A free fall control system as in claim 1, which includes a bolt and slot assembly releasably locking the lower elevating parallelogram arm to the sliding block.

11. A free fall control system as in claim 10, wherein the bolt is on the sliding block and the groove is on the underside of said arm.

12. A freefall control system as in claim 11, wherein the tension and compression means are selected to provide a predetermined amount of outward assistance for said platform while keeping the sliding block in contact with the lower arm of the parallelogram elevator.

13. A free fall control system as in claim 7, wherein the spring is mounted at one end to a short arm of the lever arm assembly, and its end opposite the vertical lift arm. A free fall control system as in claim 7, wherein the spring is mounted at one end to a long arm of the lever arm assembly, and its end opposite the vertical lift arm. 15. A free fall control system as in claim 8, wherein the spring is mounted at one end to a short arm of the lever arm assembly, and its end opposite the vertical lift arm. 16. A free fall control system as in claim 7, wherein the spring is mounted at one end to a long arm of the lever arm assembly, and its end opposite the vertical lift arm. 17. A freefall control system as in claim 15, wherein the spring is mounted at one end to a long arm of the lever arm assembly, and its end opposite the vertical lift arm. SUMMARY A free fall control system of a wheelchair platform having tension means that deflect together the long (20, 20 ') and short (24, 24') arms of a lever arm assembly (14, 14). ') which holds the lever arm sliding block (42, 42') in contact with a lifting arm (30, 30 ') during the descending deployment of the platform (12) from a concealed position on the vertical to a position of horizontal transfer. The tension means may be one or more springs (60, 60 ') and the compression means may be a gas spring (52). The forces are pre-selected to provide an aid on the vertical while maintaining the sliding block (42, 42 ') in contact with an arm (20, 20') of the lifting assembly (14, 14 ').