GB2411639A

GB2411639A - A stairlift having a pair of pivoting parallel linkages

Info

Publication number: GB2411639A
Application number: GB0404893A
Authority: GB
Inventors: Chris Bailey; Daniel Butterfield; Nigel Jakeman; Clive Thompson; Miles Thompson; Graham Mather
Original assignee: AUTORISER Ltd
Current assignee: AUTORISER Ltd
Priority date: 2004-03-04
Filing date: 2004-03-04
Publication date: 2005-09-07
Also published as: GB0404893D0

Abstract

A stairlift 10 comprises a base frame 22, pivoting linkage, a platform linear actuator 50 and platform 12. The pivoting linkage is a pair of parallel links, 24, 26 pivoted to the platform 12 and to the base 22. The linear actuator 50 moves the platform 12 from a base position to an elevated position. In the base position, a front edge 14 of the platform is adjacent to a front end of the base. When in the elevated position the front edge 14 of the platform 12 is forward the front end of the base. The radius of curvature of the linkage is less than the distance between the front pivot 34 of the linkage and the front edge 14 of the platform 12. The stairlift 10 may be provided with front, back and side guards to prevent a wheel chair rolling off the platform 12. The stairlift 10 may be disposed in a pit 40 which may be covered by a surface with warning indicia when the pit 40 is not occupied by components of the stairlift. The stairlift 10 may have pressure sensors on the platform.

Description

ë:: ace:. e.e 24 639 Stairlift This invention relates to stairlifts.

Many buildings have a small flight of steps leading to their front door which, while perhaps being architecturally necessary and even attractive, often represents an insurmountable hurdle to people confined to a wheel chair. Indeed, they represent a hurdle to people incapacitated in other ways, even to those people simply carrying a load. Such flights of steps are often unbounded by wall or stair rail. A conventional stairlift therefore is often impractical. In any event, where such stairlifts are in the form of a chair carried by a rail, they are not suitable. A person in a wheel chair must leave the wheel chair at the bottom of the flight of stairs and is therefore stranded at the top.

JP-A-11199186 discloses a lift for a person in a wheel chair to mount a small flight of stairs or steps. The lift comprises a scissor-mechanism actuated by a hydraulic jack to lift a platform embedded in the ground in front of the steps. The platform is provided with a horizontally sliding plate so that, when the platform is raised, the plate can be slid forward to abut the top of the top step of the flight of steps. A person on a wheel chair on the plate can thus be lifted from ground level in front of the steps. Then, the plate can be pushed forward to close the gap between the plate and the top step. Finally, the person in the wheel chair can manoeuvre himself or herself off the plate onto the top step. However, the arrangement is cumbersome and implies complicated control to co- ordinate the vertical upwards movement with the subsequent horizontal movement of the plate.

A. I::. cee ce: .e JP-A-10305995 discloses a step elimination mechanism employing a pair of revolving arms driven by a linear actuator from a horizontal position to a vertical position and on which a platform is disposed.

It is an object of the present invention to provide a stairlift which can lift a person in a wheel chair up a small flight of steps in a single movement.

In accordance with the present invention there is provided a stairlift comprising a base, a pivoting linkage, a platform linear actuator and a platform having a front edge, wherein the pivoting linkage is a pair of parallel links pivoted to the platform and to the base, the linear actuator moving the platform from a base position to an elevated position, wherein said front edge of the platform when the platform is in the base position is adjacent a front end of the stairlift and, when the platform is in said elevated position, said front edge is forward of said front end, and wherein the radius of curvature of the linkage is less than the distance between the front edge of the platform and a front pivot of said linkage to the platform.

A line, perpendicular a pivot axis of the pivoting linkage, joining said front edge, when the platform is in said elevated position, with its location when the platform is in said base position, therefore subtends an angle with respect to the plane of the platform of less than 45 when a line joining the pivot axes of said linkage to the base and platform is perpendicular the platform.

In use, said front end of the stair lift would be positioned near the bottom step of the flight of steps to be scaled. With normal steps, that is to say, steps with straight, parallel edges of its treads, said front edge will preferably be straight and parallel said treads. In this event, said front edge is preferably parallel said pivot axes. However, on curved stairs, or even stairs where the top step is at an angle to the bottom step, the front edge will not have this configuration, but will have one which suits the circumstances. Thus the front edge is not necessarily straight, and nor is it necessarily parallel the pivot axes.

Thus, the radius of curvature of the linkage is less than the distance between the front edge of the platform and a front pivot between said linkage and the platform. This means that the pivots of a link of the linkage to the platform and base can be vertical with respect to each other, while the front edge has moved upward and forward by an amount typical of the upward and forward extent of steps. Indeed, if particularly shallow steps are experienced, then by a combination of placing the stairlift further from the bottom step, and pivoting the linkage beyond perpendicular, the starlift can accommodate such steps by pivoting the platform over- centre. On the other hand, if steep steps are experienced, then by the opposite measures, they too can be accommodated, except that the stairlift cannot be placed so close to the bottom step that either the front edge catches the first step, or the top step is encountered before the platform has reached sufficient height.

Thus the arrangement provides a convenient lift which is easy to control requiring just one dimension of control, namely the total angle of pivot of the linkage.

Advantageously, the rear and front edges of the platform are provided with a guard to prevent a wheel chair rolling off the platform during pivoting of said linkage.

Said guard preferably comprises in each case a plate extending across at least a substantial part of the width of the platform and being movable between two positions, a first inactive position in which it is entirely beneath a top surface of the platform and a second, active position in which it extends through a slot in the platform.

Preferably, the guard has a parallel linkage connecting it to an underside of the platform about at least two pivot axes, a guard linear actuator moving the guard between said two positions.

Preferably, side guards are also provided, to prevent sideways dismounting of the platform during its movement between said base and elevated positions.

Preferably, control means are provided which, on a single actuation, control the stairlift to perform the steps of: raising at least one guard; pivoting the platform between said base and elevated positions; and lowering said at least one guard.

Preferably, said control means is arranged raise all of said guards and to lower only said guard at said front edge of the platform when the platform is in said elevated position and to lower all of said guards when the platform is in said base position.

Preferably, said stairlift is disposed in a pit at the base of a flight of steps, wherein, in said base . . . .. :: he I :: :: .. .. A: position, said platform is at ground level, the space between said platform and pit, where it is not occupied by components of the stairlift in any position of the platform, is covered with a surface provided with warning indicia. Thus, when the platform is in its elevated position, the surface and its indicia are visible and onlookers are warned to stay clear. Said indicia may comprise broad diagonal yellow lines, being a conventional well understood warning.

Preferably said base comprises a frame to which said linkage and platform actuator are pivoted. Preferably, said space is substantially filled with concrete.

Preferably, pressure sensors are provided on the platform at locations where the edge of the platform, in use, is arranged to come into contact with another structure during movement between said base and elevated positions, such that, when a solid object is interposed between said platform and structure during said movement and said platform squeezes said object against the structure, said pressure sensor detects the object and interrupts movement of the platform.

Preferably, said control means includes a position sensor so that, when the platform contacts said structure, actuation of the pressure sensor is ignored.

The invention is further described hereinafter, by way of example, with reference to the accompanying drawing, in which: Figures 1 a to e are side views of a stairlift in accordance with the present invention, shown in different degrees of elevation; Figure 2 is a perspective of a different embodiment e. ... - ë:: e.e e: . es.

of a stairlift in accordance with the present invention, shown in an elevated position; Figure 3 is a view of the stairlift of Figure 2 with a cover for its pit removed; Figure 4 is a perspective view of the stairlift of Figure 2 in its base position; and Figure 5 is a diagrammatic view showing different options for use.

Referring to Figure 1, a stairlift 10 comprises a platform 12 having a front edge 14. The platform is pivoted about a parallel linkage 20 to a base frame 22.

The linkage 20 comprises a pair of links 24,26 pivoted respectively to the platform 12 about pivot axes 32,34 and to the base frame 22 about pivot axes 36,38.

In use, the stairlift 10 is received in a pit 40 formed beneath ground level 42 in front of a flight of steps 44.

The base frame 22 is fixed (by means not shown) to the floor 46 of the pit 40. A platform linear actuator 50 is provided in the form of a ram. The ram is pivoted at one end to the base frame 22, about axis 52, and at its other end to the front link 24, about axis 54. Axis 45 is disposed intermediate the pivot axes 34,38 of the link 24 to the platform 12 and base frame 22 respectively.

Indeed, the pivot 54 is nearer to the pivot 38 than the pivot 34, so that a relatively slight linear expansion of the actuator 50 results in a substantial rotation of the link 24 about its pivot 38 to the base frame 22.

Figures lb through le show the progression of elevation of the platform 12 as the ram 50 expands. Figure le shows the maximum elevation of the platform 12. This corresponds to the length of the links 24,26, which, in Figure le. are vertical.

A: c:. .: ce: e. .. I: The links 24,26 are both H-sections having cross beams 56,58 that connect respective side arms 24a,b and 26a,b (which side arms are not distinguishable in the side views of Figures la to e).

As best seen in Figure Id, a front guard 60, a rear guard 62 and side guards 64 are provided which extend through correspondingly shaped slots 60a, 62a and 64a in the platform 12. Each guard (taking side guard 64 as an example) has a parallel linkage mechanism by which they are raised and lowered. Thus two links 66,68 are pivoted to the guard 64 about axes 70,72. The other ends of the links 66,68 are pivoted about axes 74,76 in yokes 78,80 fixed to the platform 12. An extension 82 of one link 66 is pivoted to a linear guard actuator 84, also pivoted to the platform 12 about axis 86.

Thus, in Figure la actuator 84 is shown withdrawn, pivoting the links 66, 68 in an anti clockwise direction to a maximum extent. Here, a top edge 88 of the guard 64 is flush with the top surface of the platform 12. In this position, the guard 64 closes the slot 64a, so that the surface of the platform is continuous. The same is true of each of the other guards of the platform 12.

Figure la shows a start position, where the platform 12 is flush with the ground 42 so that a wheelchair can be manoeuvred onto the platform 12 without difficulty. A control mechanism (not shown) is provided where the pressing of single button (not shown) can commence the actuation procedure. Here, the first effect is that the guards 60 to 64 are raised, as shown in Figure lb, so that the wheelchair cannot accidentally fall off the platform 12 during its subsequent manoeuvres. c

c e ac e e e e e ee e e e e e e Then, in Figure lo and d, the platform lifts as the platform actuator 50 elongates. In Figure le. the front edge 14 of the platform 12 abuts top corner 102 of the top step of the flight of steps 44. The final operation is the lowering of the guard 60, so that the wheelchair carried by the platform 12 can be manoeuvred off the platform 12 onto the top step 44.

If the button (not shown) is pressed again, then the reverse operation applies. This may, or may not be with a wheelchair occupant on the platform.

It is to be noted that the platform 12 has a section 12a that overhangs the linkage mechanism 20. This serves two purposes. The first is so that the platform overhang covers the linkage mechanism when the platform is in its base position. In fact, the platform completely closes the pit 40. The second is so that the platform 12 can reach forward while it is being elevated to co-operate with the top step of the flight of steps 44. The length of the linkage 20 determines the maximum elevation of the platform, and this elevation is essentially equal to the length of the linkage, assuming it is substantially horizontal in the base position of the platform. Most stairs have an angle of inclination of 45 or less. If the overhang 12a is at least as much as the length of the linkage, then, not only is the linkage fully covered in the base position, but also stairs of a height equal to the length of the linkage can be spanned, both elevationally and horizontally.

Moreover, stairs of lesser elevation, but greater span, can also be accommodated. Figure 5 illustrates different situations. The platform 12 is shown with its overhang .. . . . . . :: ë I- :: .- e-e .

12a and front edge 14, and links 24,26. Steps 44a show the maximum elevation possible, equal to the length of the links 24,26 and radius of arc 90, being the arc traced by the front edge 14 as the platform pivots. The arc is centred at 92, being separated from pivot axis 38 of the link 26 by an amount equal to the overhang 12a.

Steps 44b are shallow steps having a span greater than the radius of the arc 90. Nevertheless, they can be spanned in the same way as steps 44a simply by pivoting the linkage 20 beyond the vertical. In both arrangements, a consideration to be borne in mind is that the front edge 14 must not catch the top of bottom step 44c. Thus, there must be some spacing 94 between the front edge 14 when in the base position of the platform and the bottom of bottom step 44c to accommodate the arc 90. Also, when spanning shallower steps, the link 26 must not contact step 44c. Thus, if the overhang 12a is greater than the radius of the arc 90, then a minimum spacing 94 can be provided that maximises the reach of the platform 12. However, the maximum depends on the height of the steps, particularly the first step 44c. Of course, the greater the overhang 12a, the less stable the structure is, or, put another way, the more robust it must be built to prevent flexing of the overhang.

In Figures 2 to 4, a variation is shown in which the guards 64' are pivoted at the edge of the platform 12'.

The pit 40 is covered by a lid 41 to prevent children and animals falling into it when raised. The surface of the lid 41 is painted brightly in warning colours, usually yellow and black. The pit, other than where components must be accommodated during pivoting or in the different positions of the platform, is filled with concrete 43, or at least concrete blocks or the like, to support lid 41.

There is space in the pit 40 to house a motor and . . . . :: ë :: :: e hydraulic pump 98 to actuate the actuators, as well as control elements to effect an actuation operation.

In that respect, once the control elements are programmed appropriately, operation of the stairlift can be effected by the push of a single button. A button may be provide both adjacent the top step and the bottom step for actuation from either location. The button would toggle operation depending on where the stairlift was located when the button was pushed.

In one operation, suppose the platform is in the base position, in the position shown in Figure la. If either button is pressed, the first thing to happen is that the guards 60,62,64 raise. It has to be assumed that a wheelchair is on the platform. This is the case even if it is the button at the top of the stairs that is pressed. This is despite the fact that pressing of this button suggests that someone on top of the steps is calling for the stairlift, rather than some one at the top of the stairs actuating the lift on behalf of a wheel chair occupant on the platform. Nevertheless, that possibility has to be accommodated.

Next the stairlift begins lifting and advancing until the end, elevated position is reached, whereupon front guard is lowered. This permits the wheel chair occupant to leave the platform. It also permits someone calling the lift to mount the platform. When either button is pushed again, the process is reversed. In the elevated position, the controls automatically lower the stairlift to the base position after a period of time. To avoid accidents, a weight sensor detects whether an occupant is on the platform. The fact that the platform 12 is only supported by the structure of the stairlift facilitates e. . . A: :. - ce: . . this, where a strain gauge (not shown), for example, connected to the link 26, could be employed to detect additional weight on the platform.

Pressure sensors (not shown) are preferably also disposed around the periphery of the platform 12. A set may be disposed adjacent and, indeed, constitute, the front edge 14. Then, since the controls will also include position monitors, contact with an object by the front edge 14, before it should be contacting the step edge 102, can interrupt operation of the actuator 18. Likewise, the other edges of the platform are likewise provided with sensors to avoid entrapment of objects between the platform 12 and top edge 45 of the pit 40.

Claims

. . . . :: ce . :: he .e ë CLAIMS

1.A stairlift comprising a base, a pivoting linkage, a platform linear actuator and a platform having a front edge, wherein the pivoting linkage is a pair of parallel links pivoted to the platform and to the base, the linear actuator moving the platform from a base position to an elevated position, wherein said front edge of the platform when the platform is in the base position is adjacent a front end of the stairlift and, when the platform is in said elevated position, said front edge is forward of said front end, and wherein the radius of curvature of the linkage is less than the distance between the front edge of the platform and a front pivot of said linkage to the platform.

2.A stairlift as claimed in claim 1, in which said front edge is straight and parallel said pivot axes.

3.A stairlift as claimed in claim 1 or 2, in which the rear and front edges of the platform are provided with a guard to prevent a wheel chair rolling off the platform during pivoting of said linkage.

4.A stairlift as claimed in any preceding claim, in which side guards are provided, to prevent sideways dismounting from the platform during its movement between said base and elevated positions.

5.A stairlift as claimed in claim 2 or 3, in which the or each guard comprises in each case a plate extending across at least a substantial part of the width or length of the platform, as the case may be, and is movable between two positions, a first inactive . . . .. :: e. A- :: .e e.e..

position in which it is entirely beneath a top surface of the platform and a second, active position in which it extends through a slot in the platform.

6.A stairlift as claimed in claim 4, in which the guard has a parallel linkage connecting it to an underside of the platform about at least two pivot axes, a guard linear actuator moving the guard between said two positions.

7.A stairlift as claimed in any preceding claim, in which control means are provided to control operation of the stairlift.

8.A stairlift as claimed in claim 7, in which said control means has just one dimension of control, being the total angle of pivot of the linkage.

9.A stairlift as claimed in claim 7 or 8, when dependent on claim 3, in which said control means, on a single actuation, control the stairlift to perform the steps of: a) raising at least one guard; b) pivoting the platform between said base and elevated positions; and c) lowering said at least one guard.

10. A stairlift as claimed in claim 9, in which said control means is arranged raise all of said guards and to lower only said guard at said front edge of the platform when the platform is in said elevated position and to lower all of said guards when the platform is in said base position.

11. A stairlift as claimed in any preceding claim, in . . .. :: . :: :: ë which said stairlift is disposed in a pit at the base of a flight of steps, wherein, in said base position, said platform is at ground level.

12. A stairlift as claimed in claim 11, in which the space between said platform and pit, where it is not occupied by components of the stairlift in any position of the platform, is covered with a surface provided with warning indicia.

13. A stairlift as claimed in any preceding claim, in which said base comprises a frame to which said linkage and platform actuator are pivoted.

14. A stairlift as claimed in any preceding claim, in which pressure sensors are provided on the platform at locations where the edge of the platform, in use, is arranged to come into contact with another structure during movement between said base and elevated positions, such that, when a solid object is interposed between said platform and structure during said movement and said platform squeezes said object against the structure, said pressure sensor detects the object and interrupts movement of the platform.

15. A stairlift as claimed in claim 14, when dependent on claim 7, in which said control means includes a position sensor so that, when the platform contacts said structure, actuation of the pressure sensor is ignored.