GB2486449A - Stairlift rail with plastic and metal parts - Google Patents

Abstract

A stairlift rail 100 comprises a first or lower part 110 adapted to be fixed to a set of steps and a second or upper part 120 adapted to support a carriage for carrying a payload, the lower part 110 being formed from a plastics material and the upper part 120 being formed from metal. The upper and lower parts 120, 110 are preferably co-extruded, and are preferably made from aluminium and high density plastic such as polyethylene, respectively. The second or upper, metal part 120 may include a channel 124 to carry a toothed rack cooperating with a pinion on a carriage and may also include an outwardly protruding flange with an overhang surface 122 to guide a roller on a carriage.

Description

Stairlift Rail This invention relates generally to a stairlift rail and particularly to the type of stairlift rail traditionally extruded from a metal such as aluminium.

Sairlifts are used to carry a payload, such as a person, up or down a set of stairs. A carriage which carries a platform, such as a seat, for supporting the payload travels along an elongate rail which is fixed to the stair treads and extends from the bottom to the top of the stairs. The carriage is typically driven by a rack and pinion system in which the toothed rack runs along a channel in the rail and the pinion is located in the carriage.

Stairlift rails can have many different cross-sectional shapes, with each stairlift manufacturer typically utilising their own unique rail shape. A known type of stairlift rail is generally I'-shaped in cross-section, with an upright central web and upper and lower flanges. The lower flange (foot) is adapted for fastening to a set of steps, while the upper flange (head) carries the rack channel and provides a support and guide for rollers of the carriage which maintain the position of the carriage relative to the rail. In other stairlift rails the rack is mounted to a side surface of the rail and a roller bears against an opposing side surface. In such an arrangement a second roller runs along another surface of the rail to prevent rocking of the carriage with respect to the rail.

To minimise costs and weight, stairlift rails are usually hollow. The rail thus comprises a number of hollow cavities interconnected and enclosed by thin webs. Such configurations are typically achieved by extrusion of aluminium.

At its most general, the present invention proposes a composite rail composed of a plastics material and a metal.

Thus, in a first aspect, the present invention provides a stairlift rail comprising a first part adapted to be fixed to a set of steps and an second part adapted to support a carriage for carrying a payload, wherein the first part is formed from a plastics material and the second part is formed from a metal.

In this way, the rail is inexpensive to produce compared with known stairlift rails. The cost of stock metals, such as aluminium, which are typically used to extrude stairlift rails is very high, and so the present invention uses such metals in only limited amounts. Plastics, on the other hand, are comparatively inexpensive, and also readily formable.

The first part may form the lower part, base, body or backbone of the rail, and may have an outer volume which comprises the majority of the total volume of the rail, preferably more than two thirds or more than three quarters of the total volume. The second part may comprise a layer of metal formed around an upper portion, such as an upper flange, of the S first part. The second part typically covers portions of the rail that are required to withstand forces directly applied by a carriage supported by it. For example, the second part may cover one or more regions of the rail along which one or more rollers of the carriage can travel, and/or one or more regions of the rail along which a toothed rack for driving the carriage is mounted.

The first part may be configured according to a stairlift manufacturer's specific strength and/or other technical requirements. To reduce tooling costs the shape and configuration of the second part is preferably uniform for all manufacturers or for all models within a manufacturer's product range.

The first and second parts are preferably co-extruded. Such an arrangement reduces manufacturing costs because of reduced tooling, setup and trim scrap. It also minimises expensive tolerance control at the interface between the two parts.

In some embodiments the second part may be formed from aluminium and/or the first part may be formed from a high density plastic such as high density polyethylene (HDPE).

Stairlifts are typically driven by a rack and pinion mechanism, with the rack being carried by the rail and the pinion being mounted in the carriage on which the seat is fixed, Thus, the second part may include a channel arranged to carry a toothed rack for cooperating with a corresponding pinion in a carriage supported by the second part. The second part may include an outwardly protruding flange adapted to guide a roller of a carriage in order to support the carriage on the rail.

In a second aspect the present invention provides a stairlift for carrying a payload up and down a set of steps, the stairlift comprising a platform arranged to support a payload, a carriage fixed to the platform, and a rail along which the carriage is movable, the rail comprising a first part adapted to be fixed to a set of steps and an second part supporting the carriage, wherein the first part is formed from a plastics material and the second part is formed from metal.

The rail may be a stairlift rail according to the first aspect which may include any of the optional features described above, either alone or in any combination. The stairlift may be an apparatus for carrying a person up and down a set of steps, or stairs. In such a case the platform comprises a seat on which the person sits during motion of the carriage along the rail.

In a third aspect the present invention provides a method of manufacturing a stairlift rail comprising a plastics first pad adapted to be fixed to a set of steps and a metal second pad adapted to suppod a carriage for carrying a payload, the method including the step of co-extruding the first and second pads. This method reduces manufacturing costs because of reduced tooling, setup and trim scrap. It also minimises expensive tolerance control at the interface between the two pads.

In a foudh aspect the present invention provides a method of producing first and second stairlift rails, each comprising a plastics first pad adapted to be fixed to a set of steps and a metal second part adapted to suppod a carriage for carrying a payload, the method including the steps of: selecting a first profile for the plastics first pad of the first rail; selecting a second profile for the plastics first pad of the second rail, the second profile being different to the first profile; selecting a common profile for the metal second pads of the first and second rails; co-extruding the first and second pads of the first rail to achieve the first profile and common profile, respectively; and co-extruding the first and second parts of the second rail to achieve the second profile and common profile, respectively.

Thus, differently profiled rails may be produced in order to cater for different manufacturer's requirements, while also reducing tooling costs by maintaining the same cross-sectional profile shape of the metal second pad. The first, second and common profiles refer to the cross-sectional shape of the respective pads of the rail.

The skilled reader will understand that the above-described optional or preferable features of the first, second, third and foudh aspects of the invention are each applicable to any of those aspects, either singly or in any combination.

The present invention will now be more padicularly described, by way of example, with reference to accompanying drawings, in which: Figure IA shows a transverse cross-section through a stairlift rail according to an embodiment of the present invention; Figures lB and IC show upper and side elevations, respectively, of the rail of Figure IA; and Figure 2 shows a perspective view of a stairlift rail according to an embodiment of the present invention.

Figures lA-C illustrate a stairlift rail 100 according to an embodiment of the present invention. The rail 100 comprises a body part 110 made of high density polyethylene and an upper part 120 made of aluminium.

The body part 110 is generally l'-shaped in cross-section, with a lower flange 112, upstanding web 114, and upper flange 116. The body part 110 is hollow in order to minimise the amount of material used, cost and weight, while additional structural rigidity and strength is provided by internal structural webs 115.

The upper flange 116 is encased by a layer of aluminium which forms the upper part 120.

is The upper part 120 thus has two opposing overhang surfaces 122 which extend perpendicularly outwardly from the upstanding web 114 of the body part 110. The upper part 120 has a rack channel 124 which extends into the upper flange 116 and is open at the upper face of the upper part 120.

In use, the lower flange 112 of the body part 110 of the rail 100 is located above the nosings of stairs (not shown) to which the rail 100 is affixed by brackets (not shown). An elongate toothed rack (not shown) is secured within the rack channel 124 of the aluminium upper part 120, the rack interlinking with a corresponding pinion in a carriage (not shown) to drive the carriage along the rail 100. To support the carriage and maintain its orientation with respect to the rail 100, the carriage has a first set of rollers (not shown) which roll along the overhang surfaces 122 of the upper part 120 and a second set of rollers (not shown) which run along the uppermost surface of the upper part 120, 50 that the upper part 120 is pinched between the two sets of rollers.

Fig. 2 shows a perspective view of a stairlift rail 200 with the same outer profile as the rail shown in Figs. lA-C, but with some of the internal structural members 115 omitted.

Thus, the remaining features of the two rails 100, 200 are identical. Like the rail 100 of Figs. lA-C, the rail 200 is generally l'-shaped in cross-section and has a high density polyethylene lower part 210 with a lower flange 212, central web 214, and upper flange 216.

The upper flange 216 is encased within the aluminium upper part 220, which has a rack channel 224 extending therein from an upper surface.

The rail 100, 200 according to the invention is manufactured by co-extrusion of the aluminium upper part 120, 220 and high density plastic body part 110, 210. The cross-sectional profile of the body part 110, 210 is selected according to the design and configuration of the carriage to be carried. The profile may be further altered or controlled according to the strength required for a particular application, or for other technical considerations. Thus, it is to be understood that the profiles of the body part 110, 210 illustrated in Figs I and 2 are merely illustrative of two possible profile shapes. The cross-sectional profile of the upper part 120, 220, on the other hand, is intended to remain the same for all body part 110, 210 profiles, thus minimising tooling costs. Of course, it will be understood by the skilled reader that the profile shape of the upper part 120, 220 may nonetheless differ from that illustrated.

Claims (10)

1. Claims: 1. A stairlift rail comprising a first part adapted to be fixed to a set of steps and an second part adapted to support a carriage for carrying a payload, wherein the first part is S formed from a plastics material and the second part is formed from a metal.
2. 2. A rail according to claim 1, wherein the first and second parts are co-extruded.
3. 3. A rail according to claim I or claim 2, wherein the second part is formed from aluminium.
4. 4. A rail according to any of claims I to 3, wherein the first part is formed from high density plastic.
5. 5. A rail according to any of claims 1 to 4, wherein the second part includes a channel arranged to carry a toothed rack for cooperating with a corresponding pinion in a carriage supported by the second part.
6. 6. A rail according to any of claims 1 to 5, wherein the second part includes an outwardly protruding flange having an overhang surface adapted to guide a roller of a carriage.
7. 7. A stairlift for carrying a payload up and down a set of steps, the stairlift comprising a platform arranged to support a payload, a carriage fixed to the platform, and a rail along which the carriage is movable, the rail comprising a first part adapted to be fixed to a set of steps and an second part supporting the carriage, wherein the first part is formed from a plastics material and the second part is formed from metal.
8. 8. A method of manufacturing a stairlift rail comprising a plastics first part adapted to be fixed to a set of steps and a metal second part adapted to support a carriage for carrying a payload, the method including the step of co-extruding the first and second parts.
9. 9. A method of producing first and second stairlift rails, each comprising a plastics first part adapted to be fixed to a set of steps and a metal second part adapted to support a carriage for carrying a payload, the method including the steps of: selecting a first profile for the plastics first part of the first rail; selecting a second profile for the plastics first part of the second rail, the second profile being different to the first profile; selecting a common profile for the metal second parts of the first and second rails; co-extruding the first and second parts of the first rail to achieve the first profile and common profile, respectively; and co-extruding the first and second parts of the second rail to achieve the second S profile and common profile, respectively.
10. 10. A stairlift rail substantially as herein described, with reference to the accompanying drawings.