Patent Description:
<CIT> discloses a stairlift with a chair. A drive unit travels along at least one guide rail. A leveling mechanism is provided to hold the chair always in a horizontal orientation, even if the inclination angle of the guide rail is changing along the path of travel. In particular the rail of such lifts has a curved shape, like shown in <FIG> of <CIT>.

<CIT> discloses a stairlift having a chair with retractable armrest. The chair can be folded.

<CIT> discloses a stairlift chair having two separate folding mechanisms. A first folding mechanism refers to the seat surface, on which the person sits. The seat surface is foldably connected to a stationary frame. A second folding mechanism refers to the footrest, which is foldably attached to a stationary leg.

<CIT> discloses a stairlift chair in which the seat and armrests move simultaneously when the chair is folded. A footrest also folds with the armrests and seat, when the chair is folded.

<CIT> discloses a chair type elevator having a footrest. The footrest can be rotated in the vertical direction. A guide body is attached to the back of the seat and an end fixed to the footrest via a footrest rotation shaft. A lower arm, an upper arm rotatably attached to the chair body, an adjusting connector formed by rotatably connecting the other ends of the lower arm and the upper arm, and an end portion connected to the chair body are provided. An elastic body is fixed to the lower arm and having the other end attached to the lower arm. The upper arm is provided to extend from the rotation shaft, and the extended portion is engaged with the guide body via an engaging body. During examination the issuing authority came to the conclusion, that <CIT> discloses the features of the preamble of claim <NUM> as granted.

When the stairlift is not in use, the chair takes up space. It is an object of the present invention to provide an improved stairlift. This object is solved by a stair lift according to claim <NUM>; preferred embodiments are subject of the subclaims and the description.

the chair has a folding mechanism comprising.

Preferably, measured from a center of a rail in side view.

wherein the folding mechanism is adapted so that the third frontal extension is not larger than the first frontal extension.

The advantage of the inventive stairlift lies in the opportunity to fold the chair, thus reducing the space occupied by the chair during a non-use period. This improves the space efficiency during non-use.

in particular a path of folding of a most forward point of the chair does not exceed the second frontal extension.

This improves the space efficiency during the folding process. In particular, during folding/unfolding the footrest does not occupy more space in frontal direction than in the unfolded position. So, it is made sure, that during folding the footrest does not hit any obstacles which it does not hit during normal operation.

During the folding process of the chair the footrest body is automatically folded into its folded state. No additional action is necessary by the user to get the footrest body folded.

During the unfolding process of the chair the footrest body is not automatically unfolded into its unfolded state, in particular that the folding mechanism comprising a footrest steering lever for selectively activating the unfolding process of the footrest body either manually or in an actuator driven manner.

Requiring a separate unfolding action by the user in the unfolding procedure improves the ergonomics and the safety of the folding mechanism. In the opposite case the footrest would be unfolded automatically; but since the footrest is heavily protruding in the frontal direction, this could cause hurt to a user during unfolding. So, in particular therefore the footrest is adapted to be unfolded upon a user action, i.e. pressing a button or shifting a lever.

Preferably the folding mechanism comprises a leg control lever arranged parallel to the seat body, in particular arranged between the base body and the leg body. The folding mechanism is adapted so that that during folding of the seat body (i.e. moving rearwards), this causes the footrest control lever to be pushed downwards causing the footrest body to also move rearwards.

The folding mechanism is adapted so that the longitudinal shifting of the leg control lever is initiated by a lifting of the seat body in the upward direction. Lifting can be done manually or induced by an actuator in particular a motor. Lifting can be supported by an actuator pushing the leg control lever particularly in the forward direction. A spring may be provided, counteracting any gravitational force of the chair components, and in particular save energy when driving an actuator.

Preferably the folding mechanism comprises a footrest control lever arranged parallel to the leg body, in particular arranged between the seat body and the footrest body. The folding mechanism is adapted so that during folding the footrest control lever is longitudinally shifted relative to the leg body, causing the footrest body to rotate in an upward direction.

During unfolding, in particular unfolding which is caused by an unlocked soft lock, the footrest body remains initially in a folded state during unfolding of the seat. The footrest may then be unfolded by a separate activation, either manually or electrically.

Preferably the longitudinal shifting of the footrest control lever is initiated by a rotation of the leg body in rearward direction. In particular a forward movement of the leg control lever is initiated relative to the seat body, causing the footrest control lever to move downward, which in turn initiates the footrest folding inwards.

Preferably the folding mechanism comprises a knee lock mechanism, which is adapted to prevent the leg body from being folded when the chair, in particular the seat body, is in its unfolded position. In particular the knee lock mechanism is pushed into a locking position by the seat body. Without the knee lock mechanism, the leg control lever would be charged with a heavy torsional load; the lock may prevent this und thus increases stability and service life. The knee lock mechanism allows the leg control lever to be designed more compactly, thus improving the compact dimensions of the chair in the folded state.

Preferably the knee lock mechanism has a locking bar, which can be shifted between a locking position and an unlocking position. In the locking position the locking bar is adapted to interact with a locking face attached to the leg body, thereby preventing rotation of the leg body, in particular relative to the seat body and/or the base body.

Preferably the folding mechanism comprises a footrest control lever arranged parallel to the leg body and connected to the base seat body and the footrest body, wherein the folding mechanism is adapted so that during folding the footrest control lever is longitudinally moved relative to the leg body, which causes the footrest body to rotate against the leg body.

Preferably the folding mechanism comprises a footrest control lever lock for selectively establishing and releasing a rotational fixed connection between the footrest body and the seat body by the footrest control lever. In particular the footrest control lever lock is adapted so that the rotational fixed connection is established when the folding process is started, and/or in particular wherein the footrest control lever lock is adapted so that the rotational fixed connection is released when the unfolding process is started.

This feature describes a possibility to make sure that during unfolding the chair the footrest is not automatically unfolded as described above. The footrest control lever lock thereby may only provide an unfolding drive force to the footrest body, when the lock is locked, in the unlocked state the footrest control lever is not able to turn the footrest body in its unfolded state.

Preferably, the footrest body is longitudinally adjustable, and in particular the footrest control lever is longitudinally adjustable. This provides a possibility to adjust the chair to the length of the person. A taller person may require a longer leg body than a shorter person. If an adjustable footrest body is provided the footrest control lever needs also to be adjustable.

In particular the footrest control lever has.

The invention is described in more detail by means of the figures, herein shows.

<FIG> show exemplary embodiments of a generic stairlift <NUM>, to which the invention can be applied. The stairlift <NUM> comprises a drive unit <NUM> which travels along a direction of travel D from a first landing area <NUM> to a second landing area <NUM>. The direction of travel D is defined by a rail <NUM> and is limited mainly by the course of an existing stairway <NUM> in a house. The drive unit <NUM> comprises a carrier <NUM>, which serves for guiding the drive unit <NUM> at the rail and which has a drive engine (not shown). Attached to the carrier is a chair <NUM>. The carrier <NUM> has non-shown rollers, which roll along the rail <NUM>. For driving the carrier <NUM> positive engagements means (not shown) are provided on the rail <NUM>, which cooperates with driving means, in particular a driven pinion (not shown), of the drive unit <NUM>. The rail <NUM> has a curved shape, which deviates from a straight line; thus, the direction of travel will change at least once during the course of the rail <NUM>. A leveling mechanism is provided on the drive unit <NUM>, to keep the chair <NUM> always in a horizontal orientation, even if the inclination of the rail <NUM> varies during its course.

The chair <NUM> is described in more detail with reference to <FIG>. The chair <NUM> comprises a base body <NUM>, which is attached to the carrier <NUM>. Attached to the base body <NUM> is a backrest body <NUM> and a seat body <NUM>. On the seat body <NUM> the user is sitting during travel. Therefore, the seat body <NUM> may be equipped with a suitable cushion <NUM> (see <FIG>).

The seat body <NUM> is foldable along a seat axis S fixed to the base body <NUM> by a seat joint <NUM>. The seat joint <NUM> is located at a rearward section of the seat body <NUM>.

The chair <NUM> comprises a footrest body <NUM>, on which during travel a user can rest his feet on. For attaching the footrest body <NUM> at the rest of the chair <NUM> a leg body <NUM> is provided attaching the footrest body <NUM> to the seat body <NUM>. The leg body <NUM> is foldable along a leg axis L fixed to the seat body <NUM> by a leg joint <NUM>. The leg joint <NUM> is located at an upper section of the leg body <NUM> and at a forward section of the seat body <NUM>.

The footrest body <NUM> is foldable along a footrest axis F fixed to the leg body <NUM> by a footrest joint <NUM>. The footrest joint <NUM> is located at a lower section of the leg body <NUM> and at a rearward section of the footrest body <NUM>.

The terms rearward, forward, upward, downward are relative to a user's point of view when sitting on the unfolded chair. The corresponding directions "rearward direction r", "forward direction f", "upward direction u" and "downward direction d" are shown in <FIG>. As especially can be seen with reference to the leg body <NUM> these directions indicate rather an approximate direction than an exact orthogonal direction.

For causing the folding of the respective bodies <NUM>, <NUM>, <NUM> several control levers <NUM>, <NUM>, <NUM> are provided. Further an actuator <NUM> and a gas spring <NUM> is provided.

The gas spring <NUM> is attached to the base body <NUM> and at a rearward section of the seat body <NUM>. The gas spring <NUM> is adapted to provide a push force between its attachment points at the base body <NUM> and at the seat body <NUM>. The gas spring <NUM> is arranged to press the seat body <NUM> its folded state. The gas spring itself is not strong enough to fold the seat by itself from the unfolded into folded state without any additional support, so that the seat is kept unfolded while in the unfolded state (<FIG>). After a slight lifting of the seat body <NUM> the force of the gas spring <NUM> and the weight of the seat components overcome an equilibrium situation and then the force of the gas spring <NUM> suffices to press the seat body <NUM> at first in a forward direction f (see <FIG>) and second in the upward direction d (see <FIG>), resulting in a clockwise rotation according to the illustration of <FIG>.

Lifting of the seat body <NUM> can be initiated manually. Once the user lifts the seat body <NUM> manually until the equilibrium situation is reached, the gas spring <NUM> pushes the seat body <NUM> further upwards into the folded state (see <FIG> and <FIG>). Optionally the lifting of the seat body <NUM> is (with or without gas spring <NUM>) supported by an actuator, in particular a motor <NUM>. The function of the actuator <NUM> is described later.

Located in main parallel to the seat body <NUM> a leg control lever <NUM> is provided. The leg control lever <NUM> is rotatably attached to a seat control lever <NUM> (attached at the base body <NUM>) and to an upward section of the leg body <NUM>. The leg control lever <NUM> is attached to the leg body <NUM> above the leg joint <NUM>. So, upon lifting of the seat body <NUM> the leg control lever <NUM> is pushed in a forward direction (arrow P1 in <FIG>), thereby causing a rearward rotation of the leg body <NUM> relative to the seat body <NUM> (arrow P2 in <FIG>). However, the leg body <NUM> remains in a vertical orientation over the entire folding process.

Located in main parallel to leg body <NUM> a footrest control lever <NUM> is provided. The footrest control lever <NUM> cooperates with a footrest steering lever <NUM> and is further attached to a rearward section of the footrest body <NUM>, connected to footrest control lever <NUM> via footrest steering bracket <NUM>. The footrest control lever <NUM> is attached to the footrest body <NUM>, rearward to the footrest joint <NUM>. When folding the leg body <NUM> rearward (arrow P2 in <FIG>), the footrest control lever <NUM> is pushed in a downward direction d (arrow P3 in <FIG>) relative to the leg body <NUM>, thereby causing a rearward/upward rotation of the footrest body <NUM> relative to the leg body <NUM> (arrow P7 in <FIG>).

Particularly in this embodiment the footrest steering lever <NUM>, which is located at the seat body <NUM>, is kept in place relative to seat body <NUM> during folding. Consequently, the footrest steering bracket <NUM> is not rotated relative to the seat body <NUM> during folding. Consequently, the footrest steering bracket <NUM> is rotated relative to the leg body <NUM>, thus pushing the footrest control lever <NUM> downwards d (see arrow P3 in <FIG>) relative to the leg body <NUM>.

Due to the geometrical conditions, the footrest body <NUM> is folded into a vertical orientation already before the seat body <NUM> has reached its final vertical orientation (see <FIG>). The folding of the footrest body <NUM> may be supported by a footrest supporting spring <NUM>, which is shown later in <FIG>. The footrest supporting spring <NUM> is attached on the other side to the lower section of the leg body <NUM>, in particular to the leg lower body <NUM>. So, the footrest supporting spring <NUM> always tries to push the footrest control lever <NUM> downwards d, counteracting against the gravity force of the footrest body <NUM>.

The optional actuator <NUM> is attached at the seat body <NUM> and cooperates with the leg control lever <NUM>, which is partially toothed for interacting with a gearwheel of the actuator <NUM>. In an alternative embodiment the actuator <NUM> may be a linear actuator. Upon activating the actuator <NUM> the motor pushes the leg control lever <NUM> in the forward direction f, which in turn results in pushing force of the seat body <NUM> in forward direction f. As described some paragraphs earlier, this forward movement of the seat body in turn initiates the gas spring to overcome the equilibrium situation, thus supporting the seat body <NUM> when folding upwards.

In sum all steps during folding can be seen in <FIG>.

To support users of different size the leg body <NUM> is adapted to be adjustable in its length. Therefore, the leg body <NUM> has a leg upper body 40U and a leg lower body <NUM>. The leg upper body 40U and the leg lower body <NUM> are connected to each other by a non-shown snap lock device, which provides a fixation between the leg upper body 40U and the leg lower body <NUM> at discrete positions.

Corresponding thereto the footrest control lever <NUM> is adjustable in its length, as shown in detail in <FIG>. Therefore, the footrest control lever <NUM> has a footrest upper control lever 52U and a footrest lower control lever <NUM>. Both lever 52U, <NUM> are connected to each other at a shift piece <NUM> (see <FIG>) comprising a footrest control lever lock mechanism <NUM>, in the following the "softlock". In this example the softlock <NUM> comprises a softlock bracket <NUM> fixed to the footrest upper control lever 52U. The softlock bracket <NUM> provides a resilient support for a spring loaded softlock blocking pin <NUM>, which can engage selectively into one of several holes <NUM>, arranged along the length of the footrest lower control lever <NUM>.

The softlock <NUM> is adapted to provide a well-defined locking force. As long as the downward acting pushing force transmitted by the footrest control lever <NUM> is below a predefined level, the softlock <NUM> provides a fixed connection between the footrest upper control lever 52U and the footrest lower control lever <NUM> (softlock <NUM> is locked). As soon as the pushing force transmitted by the footrest control lever <NUM> is above a predefined level, the softlock blocking pin <NUM> is pushed out of the respective hole <NUM> and the fixed connection is released (softlock <NUM> is unlocked). Then the footrest upper control lever 52U and the footrest lower control lever <NUM> can be shifted laterally free relative to each other until the softlock blocking pin <NUM> engages the previous engaged hole <NUM> or another hole <NUM>.

This mechanism is also used during adjusting the overall length of the leg body <NUM>. During changing the length of the leg body, the leg upper body and the leg lower body are telescoped by applying a certain push or pull force. This push or pull force is also acting on the soft lock, thereby causing, under certain circumstances, the softlock to unlock. The length of the footrest control lever <NUM> is then adjusted according to the length adjustment of the leg body <NUM>. As soon as the leg body <NUM> reaches one of the predetermined discrete length positions, then also the softlock blocking pin <NUM> is in an overlapping condition with another hole <NUM>. Therefore, distance of the discrete length position of the leg body <NUM> corresponds to the distance of the holes <NUM> at the leg control lever <NUM>.

The softlock <NUM> is also utilized during the folding process. In <FIG> and <FIG>, when the folding process is started, the softlock <NUM> is locked. In <FIG> the pushing force is transmitted via the footrest steering lever <NUM> in the direction P3, to fold the footrest upwards u. Here the push force does not exceed the level of the softlock <NUM> or any part attached to the seat body <NUM>. In <FIG> the footrest body <NUM> is completely folded. However, the overall folding process is not completely finished. The footrest steering lever <NUM> is still pushing the footrest control lever downwards d. But since the footrest body <NUM> cannot be folded any further, the pushing force increases until it reaches the limit defined by the softlock <NUM>. Now the softlock <NUM> unlocks and the footrest upper control lever 52U is pushed downwards, without pushing the footrest lower control lever <NUM> downwards (<FIG> and <FIG>).

During unfolding, the softlock <NUM> is still unlocked. So, when the seat body <NUM> and the leg body <NUM> start turning into their unfolded position (<FIG>) the footrest control lever <NUM> has a reduced length compared to the unfolded status in <FIG>. As the leg body <NUM> now turns in a forward direction (see arrow P4 in <FIG>) the footrest control lever <NUM> is stretched. Here the footrest supporting spring <NUM> pulls the footrest lower control lever <NUM> downwards d and at the same time the footrest steering bracket <NUM> pulls the footrest upper control lever 52U upwards, until the softlock <NUM> locks in the initial position as in <FIG>. A centering spring <NUM> (shown schematically in <FIG>) urges the footrest steering handle and the footrest steering lever in a neutral position (arrow P5 in <FIG>), causing the footrest body <NUM> to maintain its folded position as shown in <FIG>. As soon as the footrest steering handle <NUM> is pushed forward f by a user, this pushes the footrest steering lever <NUM> forward f, the footrest steering bracket <NUM> anticlockwise, the footrest control lever <NUM> (locked state) upwards u, thus resulting in an unfolding the footrest body <NUM>.

<FIG> shows a knee lock mechanism <NUM> which prevents the leg body <NUM> from being folded, when the chair is unfolded. The knee lock mechanism <NUM> comprises a locking bar <NUM>, which is adapted to interact with a locking face <NUM> attached at the leg body <NUM>. When a first end <NUM> of the locking bar <NUM> abuts the locking face <NUM>, the leg body <NUM> is prevented from being rotated against the seat body <NUM> and the base body <NUM> (locking position shown in <FIG>).

The locking bar <NUM> is pivotably supported by a locking bar joint <NUM>. In this example the locking bar joint <NUM> is attached to the seat body <NUM> interfacing with the base body <NUM> and the leg body <NUM>. A second end <NUM> of the locking bar <NUM> abuts in the locking position against the base body <NUM>. When the seat body <NUM> is in the unfolded position, the seat body <NUM> pushes the locking bar <NUM> against the base body <NUM>, causing the first end <NUM> to be pushed down against the locking face <NUM>.

During folding the chair <NUM>, the seat body <NUM> is lifted upwards u. Now the seat body <NUM> pulls the locking bar <NUM> upwards away from the leg body <NUM> (see arrow P6 in <FIG>, when the bar is not lifted yet), causing also the locking bar <NUM> is to release from the locking face <NUM> (<FIG>, showing the lifted locking bar). Pulling the locking bar <NUM> is support by an extension spring <NUM> arranged between the seat body <NUM> and the first end <NUM>. As soon as the seat body <NUM> is slightly lifted the extension spring <NUM> causes the locking bar <NUM> to turn away from the locking face <NUM>. During locking the extension spring <NUM> keeps the first end <NUM> turned away from the locking face <NUM>. Only during the last phase of the chair unfolding the base body <NUM> contacts the locking bar <NUM> at the locking bar second end <NUM>. This causes the first end <NUM> to turn against the locking face <NUM> not before the last phase of the unfolding phase. This improves a smooth locking procedure.

Claim 1:
A stairlift (<NUM>), comprising
- a rail (<NUM>),
- a drive unit (<NUM>) having a chair (<NUM>) and a carrier (<NUM>), wherein the carrier (<NUM>) is adapted to drive along the rail (<NUM>), and the chair (<NUM>) is supported by the carrier (<NUM>),
the chair (<NUM>) having a folding mechanism (<NUM>) comprising
- a base body (<NUM>) fixed to the carrier (<NUM>),
- a seat body (<NUM>), foldably fixed by means of a seat joint (<NUM>) to the base body (<NUM>),
- a leg body (<NUM>), foldable fixed to the seat body (<NUM>) by means of a leg joint (<NUM>),
- a footrest body (<NUM>), foldable fixed to the leg body (<NUM>) by means of a footrest joint (<NUM>),
wherein the folding mechanism (<NUM>) is adapted so that during the folding process of the chair (<NUM>) the footrest body (<NUM>) is automatically folded into its folded state,
characterized in
that during the unfolding process of the chair (<NUM>) the footrest body (<NUM>) is not automatically unfolded into its unfolded state.