GB2579394A

GB2579394A - Improvements in or relating to stairlifts

Info

Publication number: GB2579394A
Application number: GB1819522.2A
Authority: GB
Inventors: Vazquez Fernandez Jorge; John Leathley Stephen
Original assignee: Stannah Stairlifts Ltd
Current assignee: Stannah Stairlifts Ltd
Priority date: 2018-11-30
Filing date: 2018-11-30
Publication date: 2020-06-24
Anticipated expiration: 2038-11-30
Also published as: GB201819522D0; GB2579394B

Abstract

An over-speed detection device of a stairlift has a mounting section fixed with respect to the chassis of the stairlift carriage and an operating surface engagement or wheel 10 for rolling engaging with the stairlift rail, the wheel 10 being concentric with the drive axis of a drive shaft 5 for the chassis, the over-speed detection device being independent of the drive shaft 5. Preferably a sleeve 12 is mounted about the stairlift drive shaft 5, providing a mounting for the over-speed detection device. The sleeve 12 may be fixed by means of a mounting flange 18 to a gearbox or drive facility 8 mounted on the chassis and may form a sliding fit over the drive shaft 5. The over-speed detection device may be mounted on the outer surface of the sleeve 12. The wheel 10 may rotate freely on the outer surface of the sleeve 12.

Description

IMPROVEMENTS IN OR RELATING TO STAIRLIFTS

Field of the Invention

This invention relates to stairlifts and, in particular, to an arrangement for incorporating an over-speed safety facility.

Background to the Invention

Stairlifts typically include a facility in the form of an over-speed governor for braking the stairlift carriage in the event the speed of the carriage exceeds a predetermined upper limit. Known forms of over-speed governor comprise an over-speed detection device for determining an over-speed situation together with some form of safety gear, the displacement of which is triggered by the over-speed detection device to engage with the rail and bring the carriage to a halt.

There may be a number of reasons giving rise to an over-speed situation, one of which is a failure in the main drivetrain of the stairlift.

In many stairlifts, such as our model 260 curved stairlift, the over-speed facility is mounted on the main drive shaft it being accepted that, within the drivetrain, the main driveshaft is the component least likely to fail. Mounting the facility on the driveshaft means that the facility occupies little space and the roller that forms the basis of the over-speed detection device doesn't require a separate mounting.

Changes are now proposed to the regulation governing the design of stairlifts as a result of which it will no longer be acceptable to mount at least the over-speed detection device on the main drive shaft. This change in regulation exposes stairlift manufacturers to potentially significant re-design and re-tooling costs.

It is an object of the invention to provide a method and apparatus for mounting an over-speed facility within a stairlift drive train that will go at least some way in addressing the aforementioned problem; or which will at least provide a novel and useful alternative.

Summary of the Invention

In one aspect the invention provides a method of mounting an over-speed detection device on a stairlift, the stairlift having a rail; a carriage mounted on said rail for displacement there-along, said carriage including a chassis; a drive facility mounted on said chassis; a drive shaft extending from said drive facility and being rotatable with respect thereto about a drive axis; a drive wheel mounted on said drive shaft for rotation therewith and for engagement with a drive surface on said rail, said over-speed detection device having a mounting section and an operating surface configured for rolling engagement with said rail, said method including mounting said over-speed detection device so that said mounting section is fixed with respect to said chassis, said operating surface is concentric with said drive axis but said over-speed detection device is independent of said drive shaft.

Preferably said method includes mounting a sleeve over said drive shaft, said sleeve having an inner surface and an outer surface, said inner surface being at least a sliding fit over said drive shaft; fixing said sleeve to said drive facility; and mounting said over-speed detection device on the outer surface of said sleeve.

Preferably said drive facility comprises a motor and gearbox and wherein said drive shaft extends from said gearbox, said method comprising fixing a proximal end of said sleeve to said gearbox.

In a second aspect the invention provides a stairlift carriage for mounting on a stairlift rail, said carriage including a chassis; a drive facility mounted on said chassis; a drive shaft extending from said drive facility and being rotatable with respect thereto about a drive axis; a drive wheel mounted on said drive shaft for rotation therewith and for engagement with a drive surface on said rail; and an over-speed detection device having a mounting section and an operating surface configured for rolling engagement with said rail, wherein the mounting section of said over-speed detection device is fixed with respect to said chassis and the operating surface is concentric with said drive axis but said over-speed detection device is independent of said drive shaft.

Preferably said carriage further includes a sleeve mounted over said drive shaft, said sleeve having an inner surface and an outer surface, said inner surface being at least a sliding fit over said drive shaft; said over-speed detection device being mounted on the outer surface of said sleeve.

Preferably said sleeve includes a mounting flange at a proximal end thereof In a third aspect the invention provides a stairlift including a stairlift rail and a stairlift carriage as set forth above mounted on said rail for movement there-along.

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. Subject to the scope of the appended claims, 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 preferred form of the invention will now be described with reference to the accompanying drawing in which: Figure 1: shows a schematic cross-section of a stairlift drive including part of an over-speed detection facility Figure 2: shows a similar view to Figure 1 but adapted according to the invention; and Figure 3: shows a cross-section of a sleeve forming part of the drive shown in Figure 2.

Detailed Description of Working Embodiment

Referring firstly to Figure 1, part of a drive system of a stairlift carriage is shown comprising a drive shaft 5 rotating in bearings 6 & 7. Typically the bearings are mounted within a drive facility indicated in dotted outline as 8, the drive system comprising a motor and gearbox of which the drive shaft comprises the output. In the conventional manner a pinion 9 is mounted on the distal end of the drive shaft for engagement with a rack extending along the stairlift rail (not shown) although those skilled in the art will be appreciate that the pinion could be substituted by a friction drive wheel or some other suitable drive arrangement.

The stairlift of which the drive system is part should also include an over-speed governor comprising an over-speed detection device and a safety gear triggered by the over-speed detection device in the event that the carriage exceeds a prescribed speed, to engage the rail and brake the carriage to a halt. Those skilled in the art are fully aware that there are many different forms of over-speed detection device and this invention is not limited to any particular form. In the embodiment described the over-speed detection device includes a wheel 10 that is mounted within the carriage, the periphery 11 of the wheel being in contact with the rail, such that the wheel 10 is caused to rotate as the carriage moves along the rail. As is well known in the art, rotation of the wheel I 0 causes an element within the detection device to be displaced outwardly under centrifugal force. At a predetermined speed the displacement causes the safety gear to be released, the safety gear then engaging the rail and braking the carriage to a halt.

In the prior art arrangement shown in Figure 1 the wheel 10 is mounted directly on the drive shaft 5 however changes to the regulations prescribing safety rules for the construction and installation of stairlifts provide that the over-speed detection device shall be independent from the main drive. As stated above this poses a problem for existing designs in which space to house the over-speed governor is extremely limited. Further, the proposed regulation change could result in significant expense being incurred in re-design and re-tooling.

Referring now to Figure 2, the invention addresses the problem by providing a sleeve 12 about the drive shaft 5 such that the shaft 5 can rotate freely within the sleeve. The wheel 10 of the over-speed detection device is then mounted and configured to rotate freely on the outer surface of the sleeve and concentrically about the drive axis 13. In this way the over-speed detection device is independent from the main drive.

Referring now to Figure 3, the sleeve 12 has a proximal end 14, a distal end 15, an inner surface 16 and an outer surface 17. A flange 18 is attached to the proximal end 14 to allow the sleeve to be fixed with respect to the drive shaft 5, preferably to the drive unit 8 and, more particularly, to the gearbox element of the drive unit 8.

The precise dimensions of the sleeve are not critical. The inner surface 16 must be at least a sliding fit with respect to the drive shaft 5 to allow the drive shaft to rotate freely within the sleeve, and the length of the sleeve must be sufficient to allow the periphery 11 of wheel 10 to be correctly positioned in relation to the stairlift rail. The flange 18, which may be fixed by any suitable method to the sleeve, is provided with mounting holes 19 through which bolts or the like (not shown) may be passed to effect fixing to the drive unit 8.

It will thus be appreciated that the invention provides a simple yet effective means of allowing an over-speed detection device to be mounted while, at the same time, complying with the new safety rules.