The invention relates to a stairlift comprising a rail which is mounted along a staircase extending at at least one predetermined angle to the horizontal plane, and a frame engaging said rail and arranged to move along said rail in a transport direction having a vertical component and a horizontal component, on which frame a carrier is mounted for carrying a person.

Such a stairlift is disclosed in EP 2 216 284. The frame comprises support/guide means and drive means arranged to engage the rail, for moving the frame up and down along the rail. In case a staircase comprises different sections extending at different angles to the horizontal plane, the rail follows said path and therefore also has different sections extending at different, matching angles along the staircase. The frame is thereby rotated to different, matching angles as well as it transitions from one section to the next. EP 2 216 284 describes an arrangement to keep the carrier for carrying the person in the horizontal position in all sections of the staircase, in this case by means of an adjusting motor controlled by sensors sensing the amount of rotation of the frame. According to the prior art also pre-programmed adjusting motors are known, which adjust the rotation of the carrier in dependency of the position of the frame along the rail, said rotation and amounts of adjustment being stored in memory means. The goal of the invention is to provide an alternative to these prior art stair lift systems, which is easier to produce, easier to install, more robust, more reliable, cheaper, provides more flexible usage options, provides a more comfortable user experience, causes less mounting damage to the staircase and its environment and/or provides other main or additional advantages. To that end the carrier is arranged to be moved relative to said frame by actuator means in a vertical plane extending along the horizontal component of the transport direction. It should be noted that "movement of the carrier relative to the frame in a vertical plane extending along the horizontal component of the transport direction" in this context does not exclude simultaneous movement of the carrier relative to the frame in the direction perpendicular to said plane. One advantage of such an arrangement is that movement in said vertical plane (horizontally, vertically, or a combination thereof) can be used as an adjustment to replace the rotational adjustment of the carrier, by mounting the rail at one predetermined common angle along different sections of the staircase having different angles with the horizontal plane (said staircase thus comprises at least two sections, each of said at least two sections extending at a different predetermined angle to the horizontal plane, and wherein said rail extends at one common predetermined angle to the horizontal plane along said at least two sections, and wherein said carrier is arranged to be moved relative to said frame in said plane while said frame is being moved along said rail in at least on of said sections). Thereby the aforementioned rotational adjusting means are no longer necessary or only additionally necessary. Furthermore the rail does not needs to be bent, and can be reused for other staircases.

Alternatively, the rail system can be restricted to have a limited set of possible angles of the rail (for instance 0°, 30°, 60° and 90°), for use along staircases having sections with arbitrary angles, wherein the height of the carrier above the staircase is kept substantially constant by said movement in the vertical plane. The rotational adjusting mechanism can thereby be simplified, and also the production of the rail, in particular the provision of bends in said rail, can be standardized and simplified. Also, said movement in said vertical plane can be used to avoid local obstacles, such as the edge of a ceiling which might hit a user's head.

Furthermore, said movement in said vertical plane provides for additional possibilities as explained hereinafter.

Preferably said frame is arranged to be moved relative to said frame in a direction in said vertical plane which is different than said transport direction. In one embodiment said frame is arranged to be moved relative to said frame in the vertical direction. In another embodiment said frame is arranged to be moved relative to said frame in the horizontal component of the transport direction. In both embodiments said carrier can arranged to be moved relative to said frame in such a manner that the vertical distance between the frame and the staircase is kept below a predetermined maximum distance. In the preferred embodiment said carrier is mounted on said frame by means of a linear actuator which allows movement of the carrier relative to the frame in one direction in said plane.

The staircase may comprise at least one flight section having steps and at least one floor or landing section adjacent to said flight section. In a preferred embodiment said carrier is arranged to be moved in the vertical direction relative to said frame during standstill in said floor or landing section, such that the vertical distance between the carrier and the floor or landing section becomes smaller than the vertical distance between the carrier and the steps in the flight section.

Alternatively, or in addition thereto, the movement of the carrier in said vertical plane can be operated by a user at any location along the staircase, for instance by means of buttons arranged on the carrier. In case of an emergency, for instance, the carrier can thus be lowered to allow the user to safely get off the carrier at any location along the staircase. In a further preferred embodiment said carrier is arranged to be moved in the opposite horizontal component of the transport direction relative to said frame while said frame is moving in the transport direction in said floor or landing section, such that the vertical distance between the carrier and the floor or landing section becomes smaller than the vertical distance between the carrier and the steps in the flight section. In still a further embodiment said carrier is arranged to be rotated around a vertical axis, preferably above said at least one floor or landing section.

Said carrier may comprise a chair, a seat, a footrest and/or a platform arranged to carry a wheelchair or a standing person. The chair, seat, footrest and/or platform may also be moved independently relative to the frame, and/or to each other, in said vertical plane, whereby it is for instance possible to prevent that knees or the head of the person are hurt against an obstacle, such as (the edge of) a ceiling, or to adjust the carrier according to the user's or users' preferences or measurements (manually or in a pre-programmed manner). Preferably said actuator means is programmed to move said carrier relative to said frame in a predetermined manner in dependence of the position of the frame along said rail. The information necessary for programming said actuator means may be collected when the dimensions of the staircase is initially measured and a model of the rail system is designed, such that when the stairlift is installed along the staircase, said actuator means are already pre-programmed. Said position may be determined by sensors. In another embodiment said actuator means is arranged to move said carrier relative to said frame in reaction to sensors on sensing the distance to the staircase. Said rail may be comprised of a single tube extending along said staircase or of a double tube extending along said staircase. The invention furthermore relates to a method for moving a carrier carrying a person along a staircase, wherein a rail is mounted along a staircase extending at at least one predetermined angle to the horizontal plane, wherein a frame engages said rail and moves along said rail in a transport direction having a vertical component and a horizontal component, wherein the carrier is mounted on a frame, wherein the carrier is moved relative to said frame by actuator means in a vertical plane extending along the horizontal component of the transport direction.

Furthermore the invention relates to a stairlift assembly comprising a frame, a carrier for carrying a person and actuator means, wherein said frame is arranged to engage said rail and arranged to move along said rail in said transport direction, on which frame said carrier is mounted, and wherein the carrier is arranged to be moved relative to said frame by said actuator means in a vertical plane extending along the horizontal component of the transport direction. The invention will now be elucidated by means of preferred embodiments as shown in the figures, wherein: Figure 1A shows a front view of an embodiment of a stairlift in accordance with the invention, wherein the frame is shown in three different positions along the rail;

Figure IB shows a further front view of the stairlift of figure 1A, wherein the frame is shown in three different positions;

Figure 1C shows a perspective view of a detail of the stairlift of figure 1A;

Figure 2A shows a front view of another embodiment of a stairlift in accordance with the invention, wherein the frame is shown in three different positions along the rail;

Figure 2B shows a further front view of the stairlift of figure 2A, wherein the frame is shown in three different positions;

Figure 2C shows a perspective view of a detail of the stairlift of figure 2A;

Figure 3A shows a front view of another embodiment of a stairlift in accordance with the invention, wherein the frame is shown in three different positions along the rail;

Figure 3B shows a further front view of the stairlift of figure 3A, wherein the frame is shown in three different positions; and

Figure 3C shows a further front view of the stairlift of figure 3A, wherein the frame is shown in two different positions. According to figures 1 A - 1C a stairlift comprises a rail 1 which is mounted along a staircase 2. A frame 3 engages the rail 1 and is arranged to be moved up and down along the rail 1 by an electric motor driving gear wheels or friction wheels provided in said frame 3, which engage the rail 1. An example of such a driving arrangement is described in EP 2 216 284, which is incorporated herein by reference. A carrier 4 in the form of a chair, arranged to carry a person, is mounted on the frame 3. Since in this embodiment the rail 1 is a single rail, the rail 1 is provided with a strip 11 along its length, to which strip 11 the frame 3 rests in order to prevent rotation of the frame 3 around the rail 1. In case of a gear wheel driven frame 3, a tooth rack is provided on and along the rail 1, for instance on the strip 11.

In accordance to the invention, the stairlift is in particular suited to be mounted along a staircase 2 which has different sections such as shown in the figures, wherein said sections extend at a different angle to the horizontal plane. In the figures the staircase 2 is shown as having two flight sections 21 having an angle of 45 with the horizontal plane, said flight sections 21 being connected by a horizontal landing section 22. At the other ends of the flight sections the immediately adjacent floor parts 23 are considered to be part of the staircase. Although in the figures the staircase is shown in a front view and appears to be straight, the staircase does not need to be straight and may have one or more left or right bends or may for instance be a spiral (i.e. helix shaped) staircase (i.e. the horizontal component of the transport direction is bent or curved).

In prior art stairlift systems the rail 1 is shaped in a bent form at different angles with the horizontal plane, in accordance with the angles at which the staircase extends, such that the rail 1, and therewith the frame 3 and the carrier 4, more or less extends at the same distance above each section of the staircase. According to the invention, however, the rail 1 extends at one common angle to the horizontal plane along the sections of the staircase such that the rail 1 , and therewith the frame 3, extends at a variable distance above each section of the staircase, as shown in figure 1A. According to the invention the carrier 4 is arranged to be moved relative to frame 3 such that the carrier 4 extends at more or less the same distance above each section of the staircase, as shown in figure IB. As will be shown with reference to figures 3 A - 3C, this movement can also be arranged to be in the horizontal direction, but in accordance with the embodiments shown in figures 1A - 1C and 2 A - 2C the carrier 4 is arranged to be moved up and down in the vertical direction relative to the frame 3.

This arrangement has as an advantage that, since the rail 1 extends at one fixed angle along the staircase, there is no need for changing the rotational position of the carrier 4 relative to the frame 3. This may allow for an easier, more reliable, lighter and/or cheaper construction and/or operation.

A further advantage is that the carrier 4 can, within its physical limits, be raised and lowered to any desired level, such as at the ends of the staircase 2 at the floor sections 23. In the prior art system the rail 1 needs to extend far enough to allow the carrier 4 to be at a comfortable level for the person to leave the carrier 4, as shown in figure 1A at the outer left position of the carrier 4. As shown in Figure IB at the outer left position of the carrier it is shown that the rail 1 does not need to extend as far as in Figure 1A, as the carrier 4 can be lowered independently from the vertical position of the rail. This may cause less mounting damage to the wall or floor and may obviate the need for a hingeable or telescopic rail part at this end.

Figure 1C shows the mechanism to move the carrier 4 up and down in more detail. The carrier 4 is mounted on the frame 3 by means of two vertical bars 41 extending between the seat 42 and the footrest 43 of the carrier 4. The bars 41 are mounted in two vertically extending bushings 31, such that the carrier 4 can slide up and down therein. The carrier 4 is moved up and down by means of actuator means comprising for instance a linear actuator 34, or a pneumatic or hydraulic operated cylinder, which is attached at one end to the frame 3 and at its other end to the carrier 4. The actuator is operated by an electronic controller which is programmed to move the carrier 3 up and down in dependence of the position of the carrier 3 along the rail 1. Alternatively, or additionally, the actuator can be operated in dependence of sensors, which are arranged to measure distances between the frame and/or carrier and it' s environment, such as the staircase or the ceiling.

Furthermore alternatively, or additionally, the actuator can be operated by a user at will, for instance by means of a button arranged on the carrier 4.

The embodiment as shown in figures 2A - 2C is identical to the embodiment of figures 1A - 1C, with the additional feature that the chair 4 is arranged to be rotated along a vertical axis, such that for instance the chair 4 can be rotated while the chair is above the floor part 23 in order to face away from the staircase 2, such that the person in the chair 4 can step out of the chair 4 easily. To that end the frame 3 is provided with a hinge 32 having a vertical hinge axis, as shown in figure 2C, which is operated to be opened and closed by a motor (not shown). Also, as shown in figures 2A and 2B at the right side position, the chair 4 can either be moved till above the last step before the floor section 23 and be arranged in such a vertical position that the top surface of the footrest 43 is level with the floor section (allowing for a shorter extension of the rail at the top of the staircase), or the chair 4 can be moved till above the floor section 23 and be arranged in such a vertical position that the footrest is as close to the floor as possible (allowing for a safer or easier dismounting of the person from the chair). Figures 3A - 3C show an embodiment wherein the carrier 4, in this case a wheelchair platform or a platform arranged to carry a standing person, is arranged to be moved laterally in the horizontal direction relative to the frame 3, in this case along a double (parallel) rail 1. More specifically, in case the frame 3 is moving towards a relatively high distance above the staircase 2, the carrier 3 is moved horizontally towards the staircase 2 and vice versa, such that the carrier 4 extends at more or less the same distance above each section of the staircase 2, as shown by the dashed line in figure 3C. Furthermore, as can be seen by comparing figures 3B and 3C at the left or central positions of the carrier 4, the carrier 4 can be arranged to be moved relative to the frame 3, while the frame 3 is moving in the transport direction along the rail 1 above the floor section 23 or the landing section 22, in the opposite horizontal direction such that the carrier 4 moves up and down in order to allow the wheelchair to move from the floor 23 or landing 22 onto the platform 4 and from the platform 4 to the floor 23 or landing 22. Moreover, the lateral movement of the carrier 4 can be used to slide the platform 4 laterally onto the floor section 23 at the top of the staircase 2, as can be seen by comparing figures 3A and 3B in the right position of the carrier 4. Horizontal movement of the platform 4 relative to the frame 3 may also allow the platform 4 to be moved through narrower bends in the staircase 2.

The invention has thus been described by means of preferred embodiments. It is to be understood, however, that this disclosure is merely illustrative. Various details of the structure and function were presented, but changes made therein, to the full extent extended by the general meaning of the terms in which the appended claims are expressed, are understood to be within the principle of the present invention. The description and drawings shall be used to interpret the claims. The claims should not be interpreted as meaning that the extent of the protection sought is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. For the purpose of determining the extent of protection sought by the claims, due account shall be taken of any element which is equivalent to an element specified therein.