Background Stairlift rails are often provided with a hinge to enable an end section thereof to be pivoted out of end alignment with the remainder of the rail, and into a stowed position. This has the effect of reducing the overall length of the assembly and, typically, increases access to doorways or landings when the stairlift is not in use. The hinge may be operated manually but, typically, is operated by its own electric motor.

It is important that the stairlift carriage mechanism cannot move, or attempt to move, on to the hinged section when the hinged section is in its stowed position. To this end safety mechanisms are included in the stairlift assembly to ensure that power to the stairlift carriage is cut when the hinged section of rail is displaced out of end alignment with the remainder of the rail.

When the stairlift controls are hard-wired, the safety mechanisms typically comprise contact switches operated by the hinged rail section. However, it is also common to control movements of the carriage and the hinge by radio frequency devices, but many such devices currently available do not comply with the operating standards imposed by the accrediting authorities of some countries in which stairlifts are sold. One

acceptable method currently used to address this problem is to use an induction loop arrangement to cut power to the carriage motor while the hinged rail section is otherwise than in operating position. However induction loop systems can be regarded as unsightly and are expensive to install.

It is an object of this invention to provide a safety interlocking arrangement which will address the aforementioned requirements or which will at least provide a useful choice.

Summary of the Inuention Accordingly, in one aspect, the invention provides a stairlift assembly including: a stairlift rail comprising a fixed main section and at least one end part hingedly connected to said main section, said at least one end part being displaceable about the hinged connection out of end alignment with said main section; a carriage displaceable along said rail, said carriage including an electric drive motor and safety cut-out means operable to cut power to said motor if said carriage encounters an obstruction whilst moving along said rail; interlock means constructed, arranged and operable to place a mechanical stop on said main section, in the path of said safety cut-out means, as said at least one end part is moved out of end alignment with said main section.

Preferably said stairlift assembly further includes radio control means operable to control power to said drive motor.

Preferably said assembly still further includes a hinge motor operable to hinge said at least one end part with respect to said main section; and hinge control means operable to control the operation of said hinge motor.

More preferably said hinge control means comprises further radio control means.

Preferably said rail is hollow and said interlock means is mounted substantially within said rail.

Preferably said mechanical stop comprises a pin projecting through said rail into the path of said safety cut-out means, said interlock means further including an operating part contactable with said at least one end part and operable to displace said pin into and out of the path of said safety cut-out means.

In a second aspect, the invention provides a stairlift assembly including: a stairlift rail comprising a fixed main section and at least one end part hingedly connected to said main section, said at least one end part being displaceable out of end alignment with said main section; a hinge drive motor operable to displace said at least one end part with respect to said main section; a carriage displaceable along said rail, said carriage including an electric carriage drive motor; radio control means constructed and arranged to operate said hinge drive motor and said carriage drive motor; and

mechanical safety interlock means operable, in the event of displacement of said at least one end part out of end alignment with said main section, to prevent movement of said carriage into contact with said at least one end part.

Many variations in the way the present invention may be performed will present themselves to those skilled in the art.

The description which follows is intended as an illust ration only and the absence of description of particular alternatives or variants should in no way be applied to limit the scope of the invention. Such description of specific elements which follows should also be interpreted as including equivalents whether existing now or in the future. The scope of the invention should be defined solely by the appended claims.

Brief Description of e Drawings One preferred form of the invention will now be described with reference to the accompanying drawings in which: Figure 1: shows a plan view of a stairlift rail provided with interlock means according to the invention; Figure 2: shows, in a larger scale, safety interlock means for use in a stairlift assembly according to the invention ; and Figures 3 and 4 show: part sectional, elevational, views of a stairlift rail fitted with interlock means according to the invention with the hinged rail section in a closed and partially open positions respectively.

Detailed Description of Working Embodiment Referring to the drawings, according to the invention a stairlift assembly 10 is provided which includes a rail 12 in the form of a fixed rail section 14 and an end section 16 which is hingedly mounted to the fixed section 14 so as to pivot about a hinge axis 18. As can be seen from figures 3 and 4, the end section 16 pivots between a'down'position as shown in figure 3 in which the end section 16 is in end alignment with the fixed section 14, and a raised or stowed position which is shown partially in figure 4. Using this hinging mechanism the section 16 of the rail 12 may be folded out of the way of doorways or congregating areas when the stairlift assembly is not in use.

The assembly 10 further includes a stairlift carriage shown partially at 20, the carriage including an electric drive motor (not shown) which serves to move the carriage along the rail assembly 12 in the conventional manner.

It is a requirement, when a hinged end section is fitted to the rail assembly, that some form of safety interlock feature be provided to prevent the carriage being displaced while the end section 16 is otherwise than in the fully down position. This then avoids the possibility of the carriage being displaced inadvertently off the rail or the assembly otherwise being damage.

The provision of a suitable interlock is generally not a problem where the controls for the carriage are hard-wired, but effective interlocking is more difficult to achieve when, as is often the case, the carriage is controlled via a radio link. In such instances, the hinged end member 16 is typically moved between the raised and down positions by means of a further

electric motor (not shown) also controlled by a radio link, but at a different frequency from that controlling movement of the carriage 20. In such cases, however, there is a requirement to provide some form of effective safety interlocking system which operates independently of the radio controls.

In the past, it has been common to incorporate an induction loop in the control system to provide the necessary cut-out.

However, induction loop systems are time consuming, and therefore expensive, to install.

To this end, according to the invention a mechanical interlock system 22 is provided. Since the rail 12 is typically formed from a hollow extrusion, the system 22 is conveniently located substantially within the fixed rail section 14.

In the form shown, the interlock mechanism includes a mechanical stop 24 which, when the rail section 16 is in any position other than the down position shown in Figure 3, projects through a hole 26 (Figure 1) provided in the upper wall section 25 of the fixed rail section 14, to lie in the path of safety pad 28 forming part of the carriage 20. As the safety pad 28 engages with the upstanding stop 24 it operates in the conventional manner cutting power to the carriage drive motor.

The interlock system 22 further includes a actuating part 30 which contacts the hinged rail part 16 and, depending on whether the rail section 16 is down or raised, causes the mechanical stop 24 to be retracted or extended as shown respectively in figures 3 and 4.

Turning now to Figure 2, in the form shown the interlock assembly 22 includes a base mounting channel member 32 which is held in contact with the underside of rail top wall

section 25. A first actuating arm 34 is pivotally mounted in channel member 32, the arm 34 pivoting about pivot axis 36.

Actuating part 30 is formed on the outer end of first actuating arm 34.

The assembly 22 includes a second actuating arm 38 mounted to pivot about axis 40, the second arm 38 carrying the mechanical stop 24 at the outer end thereof. It will be noted that adjacent inner ends of the arms 34 and 38 overlap at 40 and a compression spring 42 is provided to bias arm 38 in a clockwise direction about pivot axis 40 and arm 34 in a counter-clockwise direction about axis 36. Thus, when the moveable or hinged rail section 16 is in the raised position shown in Figure 4, compression spring 42 ensures that the mechanical stop 24 is extended through hole 26 in the upper surface of the fixed rail section 14. However, as the moveable rail section 16 is lowered into the down position shown in Figure 3, the section 16 comes into contact with actuating part 30 and arm 34 is rotated in a clockwise direction against compression spring 42. This, in turn, allows the arm 38 to move in a counter-clockwise direction, under gravity and, as it does so, mechanical stop 24 is withdrawn allowing the carriage to move, uninterrupted, down the remainder of the fixed rail section 14 and onto the end rail section 16.

The respective lengths of the arms 34 and 38, and the respective positions of pivots 36 and 40, ensure that a small amount of movement of the hinged rail section 16 away from the fully down position shown in Figure 3, will cause the mechanical stop to fully project through hole 26 and present itself as an obstruction to the safety pad 28 on the carriage 20.

It will thus be appreciated that the present invention provides a simple yet effective form of mechanical interlock particularly suitable for use in radio controlled stairlift installations which operates simply and reliably whenever a hinged stairlift rail section is in anything other than the down position.