GB2216869A

GB2216869A - Stair lift

Info

Publication number: GB2216869A
Application number: GB8906989A
Authority: GB
Inventors: Colin Michael Gill
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-03-29
Filing date: 1989-03-28
Publication date: 1989-10-18
Anticipated expiration: 2009-03-28
Also published as: GB8807407D0; GB2216869B; GB8906989D0

Abstract

A stair lift comprising a seat arrangement mounted on a track. For neatness and to promote smoothness in operation, a toothed rack (22) engaged by a gear wheel (20) carried by the seat arrangement is located in a cavity between wheel channels (16) of the track, the teeth of the rack being level with or beneath the upper suriace of the track. <IMAGE>

Description

Stair lift.

The invention relates to stair lifts of the kind used by old people and semi-invalids to enable them to go up and down stairs.

Stair lifts invariably have a track overlying the stair treads and either fixed to an adjacent wall or to the stairs themselves. A seat arrangement mounted on the track is sometimes hoisted up the track by means of a wire rope, but in this case the motor and winding drum required to reel in the cable need to be mounted either at the top of the staircase or in some adjacent position from where the wire rope can be guided by pulley wheels. The installation of such an arrangement can therefore be fairly complicated and expensive and, especially if the motor and winding drum are mounted at the top of the staircase concerned, can be somewhat unsightly and/or obtrusive.

In an attempt to simplify the installation of a stair lift it has been known to power the seat arrangement by means of an electric motor carried by the seat, the drive arrangement including a drive gear rotatably mounted beneath the seat and engaging a toothed rack extending longitudinally of the track. However, it has been found that this solution is not completely satisfactory. The presence of a toothed rack extending the full length of the track has sometimes been somewhat unsightly. In addition, when the rack has been located on the side of the track this has tended to tilt the seat arrangement and prevented it from sliding smoothly along the track. The invention has for its object to at least alleviate this disadvantage.

According to the invention, there is provided a stair lift having a track formed by an elongate length of extruded metal section, the section having portions forming channels for pairs of wheels carrying a seat arrangement and, between the sections forming said channels, a cavity for the reception of an elongate toothed rack, the arrangement being such that in the assembled stair lift the teeth of the rack are level with or disposed completely below the exposed upper surface of the track. The cavity for the reception of the toothed rack will preferably have at least one inturned lip to retain the rack in position therein. An exposed upper surface of the track alongside the toothed rack may form a flat surface for the laying of a flat electric cable behind the seat arrangement as it travels down the track, the electric cable powering an electric motor carried by said seat arrangement.Outermost walls of the channels will preferably have curved portions which at least partly hide the wheels from view and which safely retain the wheels in the channels. Opposite side walls of the extruded metal section may be provided with respective elongate T-slot configurations for the reception of fixing brackets by means of which the metal section can be secured to the stairs concerned.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which:- Figure 1 is a schematic side view of a stair lift embodying the invention, Figure 2 is a cross section on the line 2-2 in Figure 1, Figure 3 is a complete cross section of a length of extruded metal section a part of which is shown in Figure 2, and Figures 4 and 5 are scrap views which illustrate possible modifications which will be referred to.

Referring now in particular to Figure 1 of the drawings, the stair lift there illustrated has a track 10 formed by an elongate length of extruded metal section. A seat arrangement generally indicated 12 is carried by pairs of wheels 14,14 which are captive in portions of the track.

Referring now to Figure 2, it will be seen that the wheels 14,14 are captive in the track by virtue of their location in respective portions forming channels 16,16. Outermost walls of the channels have curved portions, as shown, which almost entirely hide the wheels from view, and which safely retain the wheels in the channels.

A geared motor unit, generally indicated 18, is carried by the seat arrangement and is adapted to drive a spur gear 20 which engages a toothed rack 22. As shown, the toothed rack is of substantially square cross section and is located in a cavity 24 which is formed between the portions of the section which form the channels 16,16. An inturned lip 25 at one side of the cavity overlies one side edge of the rack to retain it in said cavity. (The manner in which the toothed rack is longitudinally located in the cavity 24 is not shown but it will be understood that this may be by mechanical means or by a suitable adhesive). It will be seen that in the assembled stair lift the teeth 26 of the rack are substantially level with the exposed upper surface 28 of the track and in fact below the upper curled over portions of the outermost walls of the channels 16,16.The exposed upper surface 28 of the track alongside the toothed rack forms a flat surface for the laying of a flat electric cable behind the seat arrangement as it travels down the track, the electric cable, shown in chain-dotted lines in Figure 2, powering the electric motor carried by the seat arrangement. The assembled stair lift is of a particularly neat and clean appearance, and by virtue of the fact that the toothed rack is located between the channels 16,16 it can be expected that the stair lift will continue to operate for an extended period of time without any tendency for jamming to occur. The fact that the rack is located, as shown, with the ends of the teeth shrouded by portions of the extruded metal section is an important safety feature.A person stumbling against the track whilst climbing the stairs will be unlikely to suffer injury from the exposed surfaces of the track or from the remaining surfaces of the rack which are not shrouded.

The complete cross section of the length of extruded metal section is shown in Figure 3. It will be seen from this that the opposite side walls of the section are provided with respective elongate T-slot configurations 30. These are provided for the reception of fixing brackets (not shown) by means of which the metal section is secured to the stairs. When the elongate metal section has been secured in position on the staircase concerned, the exposed side wall of said section will be fitted with a decorative strip (not shown) to blank off the exposed T-slot and the fixing bracket engaging it.

In Figure 4 there is illustrated a possible modification whereby the toothed rack is located in the cavity 24. The cavity is shown in this case to be provided with a pair of oppositely disposed elongate key pieces 32 which will engage complementary grooves formed along the side surfaces of the rack (not shown). In Figure 5, there is illustrated an alternative form of extrusion in which the cavity 24 has been formed with undercut grooves 34; in this case the undercut grooves will be engaged by elongate key pieces formed along the side surfaces of the rack (not shown).

Various other modifications may be made, particularly in the manner in which the toothed rack is located in the cavity 24 and in which the elongate metal section is secured in position overlying the staircase concerned.

Claims

CLAIMS:

1. A stair lift having a track formed by an elongate length of extruded metal section, the section having portions forming channels for pairs of wheels carrying a seat arrangement and, between the sections forming said channels, a cavity for the reception of an elongate toothed rack, the arrangement being such that in the assembled stair lift the teeth of the rack are level with or disposed completely below the exposed upper surface of the track.

2. A stair lift according to claim 1, in which the cavity for the reception of the toothed rack has at least one inturned lip to retain the rack in position therein.

3. A stair lift according to either one of the preceding claims, in which an exposed upper surface of the track alongside the toothed rack forms a flat surface for the laying of a flat electric cable behind the seat arrangement as it travels down the track, the electric cable powering an electric motor carried by said seat arrangement.

4. A stair lift according to any one of the preceding claims, in which outermost walls of the channels have curved portions which at least partly hide the wheels from view and which safely retain the wheels in the channels.

5. A stair lift according to any one of the preceding claims, in which the opposite side walls of the extruded metal section are provided with respective elongate T-slot configurations for the reception of fixing brackets by means of which the metal section can be secured to the stairs concerned.

6. A stair lift constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.