GB2435463A

GB2435463A - Safety enhancement for stairlift

Info

Publication number: GB2435463A
Application number: GB0603620A
Authority: GB
Inventors: Martyn Harry Jenkins; Konrad John Higgins
Original assignee: Stannah Stairlifts Ltd
Current assignee: Stannah Stairlifts Ltd
Priority date: 2006-02-23
Filing date: 2006-02-23
Publication date: 2007-08-29
Anticipated expiration: 2026-02-23
Also published as: GB2435463B; GB0603620D0

Abstract

A stairlift has a safety device comprising a switch arrangement which will stop the stairlift carriage when it encounters an obstruction whilst moving vertically downwards. The switch arrangement may be on the underside of a footrest 16. The footrest 16 also has switches operated when the leading and trailing edges of the footrest encounter obstructions, all switches being operated by movement of a single tray-like contact pad 22 mounted around and under the footrest. After the stairlift carriage has been halted by actuation of a switch it may then reverse a short distance, away from the obstruction.

Description

IMPROVEMENTS IN OR RELATING TO STAIRIFTS

Field of the invention

This invention relates to stairlifts and, in particular, to a method of andlor means for, providing safety systems for a stairlift.

Background to the Invention

A stairlift is required, by regulation, to include safety devices positioned to be contacted by obstructions on a staircase, which serve to bring the stairlift carriage to a halt in the event the carriage contacts the obstruction. It is known to provide such devices in the form of moveable pads incorporated in the footrest of the stairlift chair.

Two pads are typically provided, arranged to detect obstructions both uphill and downhill of the carriage.

There is also a requirement to detect which pad is actuated so that the carriage can be backed away from an obstruction. In other words, if the carriage engages an obstruction on the staircase whilst moving down the staircase, a subsequent call to keep the carriage moving downwards will not be answered. However, if a call is made to move the carriage in the opposite direction, the call will be answered and the carriage will be allowed to move in the upward direction. No further downward movement will be allowed unless and until the pad circuit, originally opened on engagement with the obstruction, is again closed.

As stairlifts are mounted at steeper angles or, as described in our pending International Patent Application PCT/GB2005/000642, the rail includes a vertical section, the possibly exists that the carriage will bear down on an obstruction in a substantially vertical direction, and that one of the directional safety pads will not be actuated.

It is an object of this invention to provide a method of, and means for, which will go at lest some way in addressing the concern expressed above; or which will at least provide a novel and useful choice.

Summary of the Invention

Accordingly, in one aspect, the invention provides a stairlift including a stairlift rail moutable on a staircase, said rail having an uphill end and a downhill hill end; a carriage mounted on said rail for movement there-along; directional safety devices positioned and actuable in the event said carriage engages an obstruction present on said staircase, whilst moving towards both said uphill and downhill ends of said carriage, to cause said carriage to halt, said carriage being characterised in that it includes a further safety device positioned and actuable in the event said carriage engages an obstruction on said staircase by substantially vertical movement of said carriage; wherein said further safety device is actuable independently of said directional safety devices.

Preferably said carriage includes a chair footrest, at least some of said safety devices being included in said footrest.

Preferably all said safety devices are mounted on or included in said footrest.

Preferably all said safety devices are actuated by a common displacement member.

Preferably said further safety device includes a plurality of cut-out switches.

Preferably three cut-out switches are provided said switches being arranged in a substantially triangular pattern.

Preferably said further safety device, and each of said directional safety devices, are independently wired to a control unit operable to control the movement of said carriage along said rail.

In a second aspect the invention provides a stairlift comprising a stairlift rail for mounting on or adjacent a staircase; a carriage mounted on said rail for movement there-along; at least one safety device included in said carriage, said safety device being actuable in the event said carriage engages an obstruction present on said staircase during movement of said carriage along said rail, to cause said carriage to halt, said stairlift being characterised in that said safety device is actuable in the event said carriage bears substantially vertically down on an obstruction on said staircase, said safety device including a plurality of cut-out switches.

Preferably said carriage includes a footrest, said safety device being included in or mounted on said footrest.

In a third aspect the invention comprises a method of controlling movement of a stairlift carriage along a stairlift rail, said carriage including directional safety devices positioned and actuable in the event said carriage engages an obstruction while moving in either direction along said rail, and at least one further safety device actuable in the event said carriage bears substantially vertically down on an obstruction on said staircase, said method including the steps of, in the event one of said directional safety devices together with one of said further safety devices are actuated into an open state, determining a release direction of movement of said carriage most likely to close said directional safety device; allowing movement of said carriage in said release direction for a predetermined distance; again assessing if said one of said directional safety devices and said one of said further safety devices remain open and, if so, preventing further movement of said carriage.

Preferably said carriage has a normal operating speed, said method further including restricting said carriage to a speed substantially less than said normal operating speed whilst said carriage is moving over said predetermined distance.

Preferably said predetermined distance is in the order of 20 mm or is computed by restricting movement of said carriage to a particular time in said release direction.

Many variations in the way the present invention can be performed will present themselves to those skilled in the art. The description which follows is intended as an illustration only of one means of performing the invention and the lack of description of variants or equivalents should not be regarded as limiting. Wherever possible, a description of a specific element should be deemed to include any and all equivalents thereof whether in existence now or in the future.

Brief Description of the Drawings

One operating embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1: shows an isometric view of a typical stairlift incorporating the invention; Figure 2: shows an isometric view, from above, of a stairlift footrest incorporating safety devices according to the invention; Figure 3: shows an isometric view, from below, of parts of the footrest shown in Figure 2; Figure 4: shows a similar view to Figure 3, but with an operating component added; Figure 5: shows a partial isometric view, but from above, of parts of the footrest shown in Figures 2 to 4; Figures 6: show schematic views of the components shown in Figures 2 to 5 to to 8 illustrate the operation of the safety system; and Figure 9: shows a schematic wiring arrangement for the safety devices included in the system described.

Detailed Description of Working Embodiment

The present invention provides a safety back-up for a stairlift, a typical installation of which is shown in Figure 1. In the form shown the installation includes a rail 6 mounted on or adjacent a staircase 5. The rail has an uphill end 7 and a downhill end 8. Mounted on the rail 6, for movement along the rail between the uphill and downhill ends, is a carriage 10. The carriage typically includes a drive motor (not shown) together with controls to allow the carriage to be operated and moved along the rail. Also included, in a manner which will be described in greater detail below, are a plurality of safety devices which automatically bring the carriage to a halt in the event the carriage encounters an obstruction on the staircase as it moves towards either of the rail ends.

In the conventional manner the carriage carries a chair 12 having a seat 13, backrest 14, armrests 15 and a footrest 16. As can be seen, the footrest 16 has spaced side edges I 7a and 1 7b, and a bottom surface 18. The safety devices are typically provided on, or define, the edges 1 7a, 1 7b and bottom surface 18.

The movement of the carriage along the rail, and the response of the carriage drive motor to the safety switches and devices described below, is under the control of an electric control unit (ECU) 11 indicated schematically in Figure 1.

Turning now to Figures 2 to 5, the footrest 16 is mounted on pivoting mounting bracket 19 and, in the form shown, comprises three main elements: a main footrest member 20, a switch sub-assembly 21 and a contact pad 22.

The main footrest member 20 is directly mounted to the mounting bracket 19 and is the component on which, in use, a passenger's feet will rest. The precise form of the main footrest member 20 does not form part of this invention. It may be of any suitable shape and may, for example, take the form described in our pending Internation Patent Application No. PCT/GB2005/000763.

The switch sub-assembly 21 is mounted on the underside of the main footrest member 20. The sub-assembly 21 includes a substantially triangular-shaped base 25 having a lower or outer surface 26 and an upper or inner surface 27 (Figure 5). The surface 27 is held in spaced relationship to the underside of the main footrest member by upstanding tabs 28 on the periphery of the sub-assembly 21. The base 25 is conveniently formed from an electrical insulator such as plastics.

The sub-assembly 21 further includes an actuating bracket 30 (Figure 4) mounted adjacent the lower or outer surface 26 but displaceable laterally with respect to the surface 26 and also toward the surface 26 in a manner which will be described in greater detail below.

The contact pad 22 is a tray-like component which can be seen, in part, in Figure 2 and, in part, in Figure 5. The contact pad 22 is fixed to the actuating bracket 30 and includes an upturned peripheral flange 32 which extends upwardly about the edges of the main footrest member. As can best be seen in Figure 2, this flange 32 thus defines the side edges of the footrest assembly, the bottom surface of the footrest assembly being defined by the base 34 of the tray-like contact pad 22.

The actuating bracket 30 is mounted to the base through three projecting pins 35 which pass through slotted apertures 36 in the base 25. As can be seen on two of the three pins in Figure 5 (one being left exposed for descriptive purposes) retaining clips 38, overlying electrically conductive washers 39, retain the bracket 30 in position. It will be appreciated that the slotted nature of the apertures 36 allows the pins 35, and thus the actuating bracket 30, to move laterally with respect to the base 25.

Referring to the exposed pin 35 shown in the bottom right-hand of Figure 5, it will be seen that each pin 35 includes a collar 40 on which the washer 39 seats. It will also be noted that two electrical contacts 42, which pass through the base 25, are provided adjacent each aperture 36. Thus, when the conductive washers 39 are biased down into contact with the contacts 42, an electrical circuit is completed between the contacts. It will be appreciated that the combination of a washer 39 and its associated two contacts 42 define a cut-out switch 43 which is actuated in the event the contact pad 22 is displaced upwardly. As can be seen in the embodiment depicted, three switches 43 are provided, arranged in a substantially triangular pattern.

The actuating bracket 30 is biased away from the base 25, which in turn causes washers 39 to be biased against contacts 42, by a spiral shaped coil spring 44. The spring 44 is compressed against the underside of main footrest member 20 when the base 25 is mounted to the main footrest member.

It will also be noted that the actuating bracket 30 further includes a pair of upstanding pads 46 which project through aperture 47 in the base 25. The operating elements of cut-out switches 50a and SOb contact the pads 46 and thus the switches are activated depending on the direction of displacement of the contact pad 22. If the contact pad 22 engages an obstruction when moving in the uphill direction, then the pad 22 will be displaced to the left, as indicated in Figures 5 and 6, and the cut-out switch 50a will be activated. If, on the other hand, an obstruction is encountered whilst the carriage is moving in the downhill direction, the cut-out switch SOb will be activated.

Referring now to Figure 3, whilst the bottom cut out switches 43 could be individually wired back to the ECU, the contacts 42 are preferably wired in series by conductive strips 52 provided on the underside of base 25. The outer ends of the strips 52, comprising contacts 54 and 55, are wired to ECU 11 so that an open circuit is triggered in the event that any of the switches 43 is opened. The provision of the switches 43 in a triangular pattern ensures a cut-out is triggered no matter how a vertical obstruction is encountered.

As can be seen in Figure 9, each of the cut out switches 50a and 50b, and the series of switches 43, are independently wired back to the ECU 11. Thus, in use, whichever safety switch or switches have been triggered can be readily identified and the ECU programmed to allow subsequent movement of the carriage in response to the situation identified.

Turning now to Figure 7, the schematic diagram shows the switching configuration in the event the carriage bears down vertically on an obstruction as might occur with a rail configuration of the type shown in PCT/GB2005/000642. In this situation the obstruction applies a displacement force to the footrest in the direction of arrow F7, the directional switches 50a, SOb remain closed while one or more of the switches 43 will be opened. Since the switches 50a, SOb are wired to the ECU independently of the switches 43, the ECU can readily establish the situation and only allow a call for movement of the carriage in the uphill direction.

Whilst the provision of switches 43 accommodate obstructions encountered during vertical movement, they also give rise to a potential problem in the event the carriage encounters an obstruction, obliquely, while moving in an uphill direction. Such a scenario is shown in Figure 8. In this schematic, an obstruction applies an oblique force to the footrest in the direction of arrow F8. This causes directional switch 50a to be opened along with one of switches 43. In other words, two open circuits are present, each of which brings the carriage to a halt. The problem arises in that regulations governing stairlift design require the carriage to have the ability to back away from an obstruction and this is not straightforward when two open circuits are present.

According to one aspect of this invention, the scenario shown in Figure 8 is addressed by programming the ECU 11 to recognise which of the switches 50a or 50b is opened; and that one of the bottom switches 43 is also opened. In this particular situation the ECU responds by allowing a call to be made to move the carriage in a release direction i.e. the direction (downhill) which will allow switch 50a to close. However the ECU is programmed to only allow movement for a short distance -say 20 mm -and at a speed substantially less than the normal operating speed of the carriage, before again assessing the state of the switches 50a and 43. If, upon further assessment, both switch circuits remain open the stairlift will not operate from any of the controls and a fault condition will be issued. If, however, the switch 50a closes, then the stairlift will be permitted to respond to a call for further movement in the release direction. Normal speed will only be permitted when the ECU is alerted that both safety circuits are closed.

As described above, the ECU is programmed only to allow movement for a predetermined limited distance in the event one of the directional safety circuits is triggered along with the bottom contact circuit. It will be appreciated that, rather than programming this integer is as a unit of distance, it may be programmed as an operation for a given time at a given speed.

It will thus be appreciated that the invention, at least in the case of the working embodiment herein described, provides a novel and effective means of maintaining stairlift safety in case of all types of obstruction which could be encountered as a stairlift carriage moves up and down a stairlift rail.

Claims

Claims 1) A stairlift including a stairlift rail moutable on a

staircase, said rail having an uphill end and a downhill hill end; a carriage mounted on said rail for movement there-along; directional safety devices positioned and actuable in the event said carriage engages an obstruction present on said staircase, whilst moving towards both said uphill and downhill ends of said carriage, to cause said carriage to halt, said carriage being characterised in that it includes a further safety device positioned and actuable in the event said carriage engages an obstruction on said staircase by substantially vertical movement of said carriage; wherein said further safety device is actuable independently of said directional safety devices.

2) A stairlift as claimed in claim I wherein said carriage includes a chair footrest, at least some of said safety devices being included in said footrest.

3) A stairlift as claimed in claim 2 wherein all said safety devices are mounted on or included in said footrest.

4) A stairlift as claimed in claim 2 or claim 3 all said safety devices are actuated by a common displacement member.

5) A stairlift as claimed in any one of claims 1 to 4 wherein said further safety device includes a plurality of cut-out switches.

6) A stairlift as claimed in claim in claim 5 wherein three cut-out switches are provided arranged in a substantially triangular pattern.

7) A stairlift as claimed in any one of claims 1 to 6 wherein said further safety devices, and each of said directional safety devices, are independently wired to an electronic control unit operable to control the movement of said carriage along said rail.

8) A stairlift comprising a stairlift rail for mounting on or adjacent a staircase; a carriage mounted on said rail for movement there-along; at least one safety device included in said carriage, said safety device being actuable in the event said carriage engages an obstruction present on said staircase during movement of said carriage along said rail, to cause said carriage to halt, said stairlift being characterised in that said safety device is actuable in the event said carriage bears substantially vertically down on an obstruction on said staircase, said safety device including a plurality of cut-out switches.

9) A stairlift as claimed in claim 8 wherein said carriage includes a footrest, said safety device being included in or mounted on said footrest.

10) A method of controlling movement of a stairlift carriage along a stairlift rail, said carriage including directional safety devices positioned and actuable in the event said carriage engages an obstruction while moving in either direction along said rail, and at least one further safety device actuable in the event said carriage bears substantially vertically down on an obstruction on said staircase, said method including the steps of, in the event one of said directional safety devices together with one of said further safety devices are actuated into an open state, determining a release direction of movement of said carriage most likely to close said directional safety device; allowing movement of said carriage in said release direction for a predetermined distance; again assessing if said one of said directional safety devices and said one of said further safety devices remain open and, if so, preventing further movement of said carriage.

11) A method as claimed in claim 10 wherein said carriage has a normal operating speed, said method further including restricting said carriage to a speed substantially less than said normal operating speed whilst said carriage is moving over said predetermined distance.

12) A method as claimed in claim 10 or claim 11 wherein said predetermined distance is in the order of 20 mm or is computed by restricting movement of said carriage to a particular time in said release direction.