Improvements in or relating to stairlifts

Abstract

A stairlift has a rail 5 having boarding points 7, 8; a carriage 6 mounted on the rail; a chair 9 and a footrest 11 mounted on the carriage. The chair and footrest are displaceable, possibly simultane

Description

This invention relates to stairlifts and, in particular, to an arrangement for unfolding and folding a stairlift chair. Background to the Invention Stairlifts are often viewed as ‘medical’ devices and this can lead to resistance, on the part of those who would benefit from access to a stairlift, from installing a stairlift. There is therefore a need for stairlifts to merge into a home environment as naturally as possible, be as aesthetically pleasing as possible when not in use, and be intuitive and easy to use by persons having a variety of needs. Typically, a stairlift chair is provided with a seat and footrest which can be displaced between unfolded or use positions, in which a user can sit with feet supported, and folded positions, in which the seat and footrest are stowed, typically vertically, to minimise intrusion of the stairlift into the staircase when not in use. In many cases folding of the seat and footrest are effected manually although the prior art does describe electrical power folding of one or the other. Published International Patent Application No. WO2006 / 051316 describes a stairlift in which the seat and armrests are connected mechanically to allow simultaneous folding and unfolding when the stairlift is positioned at the top or bottom of the rail. The footrest may also be connected to the seat by means of a cable, or other mechanical connection, to ensure simultaneous folding, and an alternative is described in which the footrest is folded by an electric motor, the activation of which is triggered by a switch mounted adjacent to the seat and which is contacted as the seat approaches the folded state. In this embodiment folding of the seat and footrest is not therefore effected simultaneously. A further example of folding stairlift chair is described in published International Patent Application No. WO2021 / 239506. The particular form of chair described in this patent application comprises a seat body, a leg body, and a footrest body, the footrest body being pivoted to the lower edge of the leg body while the upper edge of the leg body is pivoted to the seat body. One motor effects pivoting of the leg body relative to the seat body while a second motor effects pivoting of the footrest body relative to the leg body, although the patent describes the use of a single motor to effect simultaneous folding / unfolding of both the seat and the leg bodies when the stairlift is at positions on the rail at which a user can mount, or dismount from, the chair. It is an object of this invention to go at least some way in providing a useful alternative to the examples described. Summary of the Invention In a first aspect the invention provides a stairlift comprising a rail having boarding points; a carriage mounted on the rail for movement along the rail between the boarding points; a chair and footrest mounted on the carriage, the chair and footrest each having an unfolded state and a folded state; motive means configured and operable to displace the chair and footrest between the folded and unfolded states; and control means to control the operation of said motive means, wherein said control means is configured and operable to cause said chair and footrest, when the chair is unoccupied, to move from the folded state toward the unfolded state as the carriage approaches a boarding point. Preferably said control means is further configured and operable to cause said chair and footrest, when the chair is unoccupied, to move from the unfolded state to a folded state as the carriage departs from a boarding point. Preferably the control means is configured and operable to ensure that the chair and footrest reach fully unfolded states as the carriage arrives at a boarding point. Preferably said chair includes a seat displaceable between an unfolded and folded state; and wherein said motive means comprises a first motive source operable to displace said seat between unfolded and folded states and a second motive source operable to displace said footrest between unfolded and folded states. Preferably said control means is configured and operable to control said first and second motive sources such that said seat and footrest leave the folded states substantially simultaneously and arrive at the unfolded states substantially simultaneously. Preferably the chair includes a seat axis about which said seat pivots when moving between the unfolded and folded positions, said stairlift further including a footrest axis about which said footrest pivots when moving between the unfolded and folded positions, said control means being configured to monitor the angular position of said seat about said seat axis and the angular position of said footrest about said footrest axis. Preferably said control means includes an encoder mounted on said seat axis and an encoder mounted on said footrest axis. Preferably said control means is further operable to monitor the speed and position of the carriage on the rail and, when the carriage is moving on the rail with the chair in a folded state, and at a position of the carriage on the rail, to cause the chair and footrest to commence moving toward an unfolded state. The invention may comprise any novel combination of individual elements or components described in the following example that may combine to provide a stairlift and / or a method of controlling aspects of a stairlift and should not be confined to the particular combination or combinations of elements or components described. 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. The scope of the invention should be limited by the appended claims alone. Brief Description of the Drawings One form of stairlift control embodying the invention will now be described with reference to the accompanying drawing in which: Figure 1: shows a schematic front view of a stairlift configured and controlled according to the invention; and Figure 2: shows a sequence of schematic views of a stairlift folding arrangement according to the invention. Detailed Description of Working Embodiment As shown in the drawings a stairlift is provided comprising a rail 5 and a carriage 6 mounted on the rail for travel between a lower boarding point 7 and an upper boarding point 8, the boarding points being positions at which a user mounts, and dismounts from, the stairlift. The boarding points 7 &8 are typically located adjacent to the ends of the rail, but further boarding points may also be provided at intermediate positions on the rail, particularly where the stairlift serves more than one level in a building. The stairlift further includes a chair 9 mounted on the carriage, in the example shown, by way of interface 10. In this example a footrest 11 is mounted on the lower end of the interface 10 although, in other embodiments, the footrest may be provided integrally with the chair. Conventionally, the chair 9 comprises a seat 12, a backrest 13 and a pair of armrests 14 and is foldable, as shown in Figure 2, from an unfolded or use state, as shown in (a), to a fully folded state, as shown in (d), views (b) and (c) showing intermediate folding states. In the particular example shown, the seat 12 folds in a simple pivoting action about seat pivot axis 15 but it should be appreciated that the invention applies equally to chair arrangements such as described in GB2572807 and GB2623865 in which the folding action of the seat involves a more complex action that, nevertheless, includes movement of the seat about a pivot axis. The footrest, also, preferably pivots, in the example shown, about a footrest pivot axis 16. In the depicted example the stairlift operates under the control of control means such as electronic control unit (ECU) 18 which is located in the carriage 6 in this example, but may, alternatively, be mounted in the chair 9. As stated above, when the stairlift is not in use it will typically be positioned at a boarding point with the chair and footrest in folded states. In the event the stairlift is required by a user at a different boarding point, a call is made, for example, by using one of the remote call switches 20 located adjacent to the boarding points 7 &8 so that the stairlift can be moved, while unoccupied and still folded, to the boarding point at which the intending user is waiting. It is a feature of the invention that, as the stairlift approaches the intending user at the point of calling, the chair automatically unfolds ready for use. The movements of both the seat 12 and footrest 11 are preferably displaced by separate electric motors (not shown) under the control of ECU 18, or under the control of a separate ECU, which is configured to ensure that the seat and footrest unfold and fold simultaneously; that is to say, each leaves one extreme of travel (folded or unfolded) and arrives at the other extreme of travel (unfolded or folded) at the same time. In those examples in which the chair and footrest move about pivot axes, encoders (not shown) may be mounted on each of the axes to provide feedback to the ECU thereby allowing the respective positions of the seat and footrest to be monitored so that the ECU is able to exercise the described control. A particular feature of this invention is that the ECU 18 is configured and operable to monitor speed and position of the carriage on the rail so that, when a call is made and the stairlift approaches the intended boarding point in a folded state, with speed determined and at a defined position of the carriage on the rail, the ECU 18 causes the seat and footrest to start unfolding. Thereafter the speed of unfolding is controlled so that unfolded states, preferably fully unfolded states, of both seat and footrest are arrived at as the carriage arrives at the boarding point. Similarly, if the carriage is called from a remote boarding point while the chair is unoccupied and the seat and footrest are in the unfolded states, the control unit 18 is configured to cause the seat and footrest to fold as the carriage departs from its then position and moves toward the point of calling. By way of example only, if the time-to-unfold is 3 seconds, then the ECU 18 is programmed to commence unfolding when the carriage is at a point on the rail when, at its current speed, the carriage will reach the approaching boarding point in 3 seconds. Whilst the invention has been described as applied to the footrest and seat of a stairlift chair, those skilled in the art will appreciate that similar powered control may also be applied to the armrests and / or a power swivel (if fitted) to displace in combination with the seat and footrest. Thus the invention, at least in the case of the embodiment described above, ensures that when an unoccupied stairlift is called to a boarding point, the chair and footrest unfold automatically, as the stairlift approaches, providing a visually appealing presentation to the intending user.

Claims

1. A stairlift comprising a rail having boarding points; a carriage mounted on the rail for movement along the rail between the boarding points; a chair and footrest mounted on the carriage, the chair and footrest each having an unfolded state and a folded state; motive means configured and operable to displace the chair and footrest between the folded and unfolded states; and control means to control the operation of said motive means, wherein said control means is configured and operable to cause said chair and footrest, when the chair is unoccupied, to move from the folded state toward the unfolded state as the carriage approaches a boarding point.

2. A stairlift as claimed in claim 1 wherein said control means is further configured and operable to cause said chair and footrest, when the chair is unoccupied, to move from the unfolded state to a folded state as the carriage departs from a boarding point.

3. A stairlift as claimed in claim 1 or claim 2 wherein the control means is configured and operable to ensure that the chair and footrest reach fully unfolded states as the carriage arrives at a boarding point.

4. A stairlift as claimed in any one of claims 1 to 3 wherein said chair includes a seat displaceable between an unfolded and a folded state, and wherein said motive means comprises a first motive source operable to displace said seat between unfolded and folded states and a second motive source operable to displace said footrest between unfolded and folded states.

5. A stairlift as claimed in claim 4 wherein said control means is configured and operable to control said first and second motive sources such that said seat and footrest leave the folded states substantially simultaneously and arrive at the unfolded states substantially simultaneously.

6. A stairlift as claimed in claim 4 or claim 5 wherein the chair includes a seat axis about which said seat pivots when moving between the unfolded and folded positions, said stairlift further including a footrest axis about which said footrest pivots when moving between the unfolded and folded positions, said control means being configured to monitor the angular position of said seat about said seat axis and the angular position of said footrest about said footrest axis.

7. A stairlift as claimed in claim 7 wherein said control facility includes an encoder mounted on said seat axis and an encoder mounted on said footrest axis.

8. A stairlift as claimed in any one of the preceding claims wherein said control facility is further operable to monitor the speed and position of the carriage on the rail and, when the carriage is moving on the rail with the chair and footrest in folded states, and at a position of the carriage on the rail, to cause the chair and footrest to commence moving toward unfolded states.

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