GB2409446A - Stairlift having chair levelling about two axes - Google Patents

Abstract

A stairlift assembly in which the (12, fig 1) stairlift chair can be levelled about orthogonal axes A-A and B-B. The stairlift assembly including a rail, a carriage 30 mounted for movement along the rail, and the seat pivotally mounted to the carriage. Compensation is also made for chair tilting due to sections of the stairlift rail being slightly out of vertical. The motion about the axes may be effected in response to information held in an electronic memory, or in response to information received from a level sensor eg 32 on the chair. Preferably, the additional levelling about axis B-B is carried out by moving a side roller 22 via a worm drive (40-54, figs 3 and 4).

Description

IMPROVEMENTS IN OR RELY TING TO STAIRIFTS

Field of the Invention

This invention relates to stairlifts and, in particular, to a method of and/or means for, maintaining the chair of a stairlift assembly level as the stairlift carriage moves along a curved rail.

Background to the Invention

It is well known that, as a stairlift carriage moves through a transition bend on a stairlift rail, the chair, which is mounted on the carriage, must be repositioned to ensure that the seat surface of the chair remains level at all times. In traditional stairlift assemblies such levelling was effected mechanically, either by tilting the chair with respect to the carriage and rail, or by titling the entire chair and carriage assembly with respect to the rail.

More recently stairlifts have been developed in which the chair is levelled by a dedicated Icvelling motor under electronic control. One such form of Icvelling is described in our European Patent 0 738 232.

Whilst the need to level in the direction of travel has long been recognised, we have observed that the chairs of some stairlift assemblies tilt to a noticeable extent in other directions, particularly forward and back. Typically such tilting occurs as the carriage moves through inside/outside bends and through helical bends, but tilting may occur at other positions of the carriage on the rail.

Limitations arising in the manufacture of a stairlift rail mean that, in some instances, the intended vertical axis of the rail will not be aligned exactly vertically over the entire length of the rail. This lack of true verticality will lead to the tilting mentioned above.

Verticality issues can also arise during installation. Often when a new installation is brought to site, it is discovered that some of the staircase treads on which the rail is to be mounted, are not level. As a consequence the installer must use packing in an attempt to restore verticality to within acceptable tolerances.

Regardless of how the lack of verticality might arise, the consequences are exacerbated by the recent tendency to reduce the vertical dimension of the rail, thereby reducing the physical and visual impact of the rail. The smaller the vertical dimension of the rail, the less the spacing between the carriage rollers engaging upper and lower parts of the rail respectively. This means that small out-of-vertical deviations of the rail can translate into significant titling of the carriage and chair in a direction perpendicular to the direction of travel of the carriage.

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

Summary of the Invertio'?

Accordingly, in a first aspect, the invention provides a method of controlling the alignment of a stairlift chair in an assembly including: a stairlift rail; a carriage mounted for movement along said rail; a stairlift chair mounted on said carriage, said chair being capable of pivotal movement with respect to said carriage about a first pivot axis arranged substantially perpendicular to the direction of movement of said carriage along said rail, said method being characterized in that said chair is, if deemed necessary, also displaced about a second pivot axis which is arranged orthogonal to said first pivot axis.

Preferably said method further includes sensing the level of said chair as said carriage moves along said rail, and displacing said chair about said first and/or second axes, as the need arises, in order to maintain said chair substantially level.

Alternatively, said method further includes storing in an electronic memory information representing the desired alignment of the chair at various positions of the carriage along the rail and, as the carriage reaches a particular position on the rail, causing control means acting in response to the information in said memory to effect movement of said chair about said first and/or second pivot axes to achieve said desired alignment.

In yet a further alternative, motion about one of said first and second axes may be effected in response to information held in an electronic memory determining the correct alignment of said chair about said one of said first and second axes, whilst motion of said chair about the other of said first and second axes may be effected in response to an out of alignment condition being sensed.

In a second aspect, the invention provides a stairlilt assembly including: a stairlift rail; a carriage mounted for movement along said rail; a stairlift chair mounted on said carriage, said chair being displaceable with respect to said carriage about a first pivot axis substantially perpendicular to the direction of movement of said carriage along said rail, said assembly being characterized in that said chair is also displaceable about a second pivot axis orthogonal to said first pivot axis.

In a third aspect the invention provides a stairlift carriage and chair assembly mountable on a stairlift rail for movement along said rail in a direction of travel, said assembly being characterized in that said chair is pivotable with respect to said carriage about an axis which, when said assembly is mounted on said rail, lies substantially parallel to said direction of travel.

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 operating embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1: shows a front view of a stairlift carriage on a stairlift rail; Figure 2: shows an isometric view of part of the carriage shown in Figure 1, with a number of components omitted for clarity; Figures 3A: show views along the line X-X in Figure 1, in three alternative to 3C positions; and Figure 4: shows an exploded view of the components used to effect level about axis B-B in Figure 2.

Detailed Description of Working Embodiment

The present invention provides a method of, and means for, establishing a level seat surface both in the direction of travel of the stairlift carriage, and perpendicular to such direction. Levelling about an axis perpendicular to the direction of travel is entirely conventional and has been practiced for so long as curved stairlifts have existed. Levelling in the orthogonal direction is novel and is the characterising feature of this invention.

It will be appreciated that, for so long as the chair is properly levelled in the direction of travel, the orthogonal axis will be horizontal.

Referring to Figure 1, the main operating components of a carriage assembly 10 are shown mounted on a horizontal section of stairlift rail 12. By way of example only, the components of carriage 10 may be as described in published International Patent Application WO 02/064481, the contents of which are incorporated herein by reference.

Broadly, the downwards load imposed by carriage 10 is supported by roller pairs 14a and 14b which roll on the upper surface of rail 12. Bottom roller 16 contacts the lower edge of the rail 12 and ensures the roller pairs 14a and 14b remain in contact with the rail 12 - particularly when the carriage is traversing a sloping section of rail.

Leading and trailing side roller pairs, one of each of which is shown at 18a and 18b, help to steer the roller pairs 14a and 14b as the carriage moves through inside and outside bends, whilst the movement of the carriage through transition bends is accommodated by the spacing between roller pairs 14a and 14b on the one hand, and the bottom roller 16 on the other hand, being allowed to vary under the control of springs 20.

The final, principal element of control is provided by lateral rollers 22 and 24 (Figure 2) which are mounted on the central axis of the carriage and resist rotation of the carriage about the longitudinal axis of the rail 12, roller 22 acting against the upper outer surface of the rail whilst roller 24 acts against the lower inner surface of the rail.

As stated above, levelling about an axis which is perpendicular to the direction of travel of the carriage 10 along the rail 12 is well known and is entirely conventional.

This axis is indicated as A-A in Figure 2. By way of example, levelling about axis A- A may be effected mechanically or may be effected by a separate levelling motor (not shown), under electronic control, which pivots the chair (indicated schematically by dotted lines 30) with respect to the carriage 10. One example of the latter is described in our European Patent 0 738 232, the entire contents of which are incorporated herein by reference.

Alternatively, a simple level sensor 32 may be incorporated in the chair structure, the sensor 32 giving an electronic signal representing the inclination or level of the chair 30. This signal is fed to suitable intelligence and processed into a control signal which, in turn, operates a motor, linear actuator or the like, to maintain the level of the chair within predetermined limits.

In accordance with this invention, levelling of the chair 30 is also effected about axis B-B in Figure 2. In this way, compensation can be made for any tendency of the chair to tilt forwards or rearwards due to any out-of-vertical alignment of the rail.

Turning now to Figures 3A to 3C, & 4, in the case of the particular carriage roller arrangement depicted and described herein, levelling about axis B-B is preferably effected by varying the position of lateral roller 22 with respect to the carriage chassis 34. To this end, roller 22 is mounted on bearing block 36 which is in sliding contact with the underside of motor plate 38.

Projecting from the rear edge of bearing block 36 is a shaft 40 in which is formed a helical channel 42. Shaft 40 is receivable within cylindrical bore 44 of a rotating control screw 46, the bore including a projection 48 which engages within channel 42 to ensure that rotation of the control screw 46 translates into displacement of shaft 40 in the direction of arrow 50.

In the particular example described herein, rotation of the control screw 46 is effected by drive motor 52. A worm gear 54 is mounted on the output shaft of motor 52, the gear 54 engaging suitable drive grooves on the periphery of control screw 46.

It will be seen from Figures 3A to 3C that close association of bearing block 36 with the underside of motor plate 38 prevents rotation of the bearing block as the control screw is being rotated to displace the bearing block.

In Figure 3A, the levelling arrangement is shown in a 'neutral' position such as is the case when the rail is exactly vertical. In Figure 3B the vertical axis of the rail is shown titled forward by about 5 . In this situation motor 52 is actuated to turn the control wheel in a direction which will extend the shaft 40 further out of bore 44 until the seat surface is again level.

In Figure 3C, the vertical axis of the rail is tilting back by about 5 and thus the control screw is rotated to draw the shaft 40 further into bore 44.

Levelling motor 52 may be under the control of a signal derived directly from an analogue sensor, such as sensor 32 mounted on the chair structure. Alternatively, a process much as described in European Patent 0 738 232 may be employed and any out-of-vertical imperfections in the rail 'learned' and stored in memory in accordance with their position on the rail. The degree to which the motor 52 need be actuated, and the direction of actuation is also stored so that, as an out-of-vertical section of rail is encountered, the motor 52 is automatically actuated to ensure any titling of the seat is kept within predetermined limits.

It will be appreciated that the present invention is not restricted to those stairlift installations in which levelling of the chair about axis A-A is effected by a separate motor under electronic control. Indeed even mechanically Ievelled stairlifts may be provided with suitable auxiliary levelling systems to compensate for excessive titling in a forward or rearward direction.

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 a stairlift chair level irrespective of the vertical alignment of the rail.

Claims (6)

1. Claims 1. A method of controlling the alignment of a stairlift chair in

   an assembly including: a stairlift rail; a carriage mounted for movement along said rail; a stairlift chair mounted on said carriage, said chair being capable of pivotal movement with respect to said carriage about a first pivot axis arranged substantially perpendicular to the direction of movement of said carriage along said rail, said method being characterised in that said chair is, if deemed necessary, also displaced about a second pivot axis which is arranged orthogonal to said first pivot axis.
2. 2. A method as claimed in claim [further including sensing the level of said chair as said carriage moves along said rail, and displacing said chair about said first and/or second axes, as the need arises, in order to maintain said chair substantially level.
3. 3. A method as claimed in claim [further including storing in an electronic memory information representing the desired alignment of the chair at various positions of the carriage along the rail and, as the carriage reaches a particular position on the rail, causing control means acting in response to the information in said memory to effect movement of said chair about said first and/or second pivot axes to achieve said desired alignment.
4. 4. A method as claimed in claim I further including effecting displacement relative to one of said first and second axes in response to information held in an electronic memory determining the correct alignment of said chair about said one of said first and second axes, whilst displacement of said chair relative to the other of said first and second axes may be effected in response to an out of alignment condition being sensed.
5. 5. A stairlift assembly including: a stairlift rail; a carriage mounted for movement along said rail; a stairlift chair mounted on said carriage, said chair being displaceable with respect to said carriage about a first pivot axis substantially perpendicular to the direction of movement of said carriage along said rail, said assembly being characterized in that said chair is also displaceable about a second pivot axis orthogonal to said first pivot axis.
6. 6. A stairlift carriage and chair assembly mountable on a stairlift rail for movement along said rail in a direction of travel, said assembly being charaeterised in that said chair is pivotable with respect to said carriage about an axis which, when said assembly is mounted on said rail, lies substantially parallel to said direction of travel.