Patent Description:
<CIT> discloses a stairlift. The stairlift comprises a chair mounted on a drive assembly. The drive assembly 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.

<CIT>, disclosing the preamble of the independent claims, discloses a stairway chairlift for transporting passengers. The seat of the chairlift is pivotally mounted to a horizontal pate which moves inwardly or outwardly in response to rotation of the seat so as to maintain a substantially constant clearance between the seat and the stairway wall. It also comprises a pair of arms which can be lowered to form a retaining barrier around the seat and then raised to permit the passenger to leave the seat.

Typically, stairlifts have a chair which can be folded in order to safe space on the staircase when the stairlift is not in use. In most cases, the armrest can be folded by rotating the armrest partly around a horizontal axis. When unfolding the armrest, the armrest is rotated downwards until it reaches a mechanical stop and the armrest stays in this position due to gravitational forces. To support different sizes of person there are curved armrests for small users and straight armrests for large users. Both types rotate around a horizontal axis.

It is the object of the present invention to develop an improved stairlift, providing improved safety and comfort. The object of the invention is solved by method of controlling a stairlift and a stairlift according to the independent claims; preferred embodiments are subject of the subclaims and the description.

An inventive method of controlling a stairlift is disclosed in appended claim <NUM>. Specific embodiments of said method are disclosed in appended claims <NUM> to <NUM>. An inventive stairlift is disclosed in appended claim <NUM>. Specific embodiments of the inventive stairlift are disclosed in claims <NUM> and <NUM>.

In the inventive stairlift the armrest serves in particular for securing the passenger against dropping out of the chair. This is only possible in certain positions of the armrest. By the inventive detection step it can be checked, whether the armrest is in a position of securing the person. If the armrest is not in appropriate position of securing the person, e.g. the engine may not be driven the swiveling mechanism may be blocked.

In an embodiment the functionality may be a functionality of the drive engine, in particular driving the drive engine or stopping the drive engine or altering a drive speed of the drive assembly along the rail.

In an embodiment the drive assembly comprises a swivel engine for swiveling the chair along a vertical axis. In this embodiment the at least one functionality of the stairlift is a functionality of the swivel engine of the drive assembly, in particular driving the swivel engine or stopping the swivel engine or altering a swivel angle of the chair. Here the knowledge of the armrest position can be used to decide whether the swivel engine is e.g. allowed to swivel the chair or not. Since the armrest may radially protrude in several positions, it may improve the safety, if the chair is being hindered from swiveling.

In an embodiment the step of controlling a functionality of the drive assembly is performed additionally as a function of the position of the chair along the rail. The spatial conditions may vary at different positions along the rail. Thus some restrictions in the functionality can be limited to certain positions.

The inventive stairlift has an angular sensor for detecting the angular position of the armrest.

In particular, the armrest can be pivoted about a vertical axis. This allows that in a radially outward armrest position the armrest can be used for supporting the person getting on or off the chair. However this position of the armrest may be comfortable during entry, the position must be changed due to the above mentioned safety reasons.

In an embodiment the control unit is adapted to control the drive assembly as a function of the angular position detected by the angular sensor. The advantageous and the improvements described with reference to the method are generally applicable to the apparatus claims.

According to the invention, the chair comprises a, in particular a spring loaded, latch mechanism to lock the armrest in a, in particular in a discrete, angular position. A latch sensor is provided for detecting, whether the latch mechanism is in a locked state or an unlocked state. The step of controlling a functionality of the drive assembly can be performed additionally as a function of the result of the checking step. By this functionalities which require safety measurements can be supported by an improved safety standard.

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

<FIG> shows an exemplary embodiment of an inventive stairlift <NUM>. The stairlift <NUM> comprises a rail <NUM> and a drive assembly <NUM> with a drive engine <NUM>, which travels along the rail <NUM>. The drive engine <NUM> drives the drive assembly <NUM>. A chair <NUM> having a seating <NUM> and a backrest <NUM> is mounted to the drive assembly <NUM>. The chair <NUM> has two armrests <NUM> mounted by a hinge <NUM>, which allows a pivotal movement of the armrest <NUM> along a vertical axis R. The stairlift <NUM> comprises further a swivel engine <NUM>, which is adapted to swivel the chair <NUM> relative to the drive assembly <NUM> along a vertical axis S. By swiveling the chair <NUM>, a collision of the chair <NUM> or the person sitting on the chair with obstacles in the path can be avoided. A control unit <NUM> is provided for controlling the functions of the stairlift <NUM>.

<FIG> shows the left armrest <NUM> in different angular positions A-D. In position A no person can be accommodated on the chair <NUM>. The position A is for storing the chair <NUM>, when the stairlift <NUM> is not in use. In this armrest position also the chair <NUM> can be folded to reduce the storage space.

In position B a small or medium sized person can be accommodated on the chair, in position C a tall sized person can be accommodated. In the position B and C the armrest serves also for securing the person against dropping out of the chair.

In position D, the armrest <NUM> is opened for allowing a person to enter or leave the chair <NUM>,e.g. from or to a wheelchair. In position D it is not allowed to move the chair. In an embodiment the drive engine <NUM> may be blocked, when the armrest position A or D is detected. Then it is prevented to move the drive assembly along the rail.

<FIG> shows the upper part of the chair <NUM> in a first angular position α = <NUM>°. There are shown two clearance zones Z<NUM>, Z<NUM>. The first zone Z<NUM> is a small clearance zone, which is kept free from any obstacles <NUM>. It allows that the chair <NUM> can be swiveled along a swivel angle α of even +/-<NUM>° (in both directions), without colliding with an exemplary obstacle <NUM>, when the armrest is in position A or B. However in practice the swivel motion will usually be stopped at α = +/-<NUM>°, because a footrest (non-shown ) may collide latest at α = +/-<NUM>° with the rail <NUM>.

If the armrest <NUM> is in position C or position D, the armrest <NUM> may collide at a certain angular position with the obstacle <NUM> (<FIG>). Therefore a second clearance zone Z2 is established, which has a larger radial extent, but a reduced angular extent compared to the first clearance zone Z1. Accordingly a maximum angular position αmax of e.g. <NUM>° is defined and linked to armrest position C. These maximum angular positions may be defined for each individual stairlift installation and each armrest position, based on the limiting features at the respective individual staircase. Further the maximum angular positions may be defined separately for individual positions of the path of travel. Because at a position of the rail, where are no obstacles, no additional limitation of the swivel angle is necessary. In an embodiment a obstacle clearance zone may be provided around an obstacle. The obstacle clearance zone must not intrude into the first and/or second clearance zones.

<FIG> shows the armrest locking mechanism. In the hinge <NUM> a movable latch <NUM> is provided which is rotatably supported against a ring shaped latch plate <NUM>. In this example the latch <NUM> is fixed to the armrest; the latch plate <NUM> is fixed to the chair <NUM>. The latch plate <NUM> comprises a number of latch seats 10A-10D, in which the movable latch <NUM> can protrude. When the movable latch <NUM> protrudes into one of the latch seats <NUM>, the latch <NUM> is in a locked state (shown in <FIG>), otherwise in an unlocked state. A spring <NUM> biases the movable latch <NUM> into the locked state. With the help of a bowden cable <NUM> and a not shown actuating lever a user can bias the movable latch <NUM> against the spring force of the spring <NUM> into the unlocked state.

An optocoupler <NUM> is provided to detect if the movable latch <NUM> is in a locked or unlocked state. In the unlocked state a vane <NUM>, which is fixed to the latch <NUM>, cuts through a light beam of the optocoupler. The optocoupler cannot detect the current angular position A-D of the armrest <NUM>.

When the movable latch <NUM> is in an angular position so that it can protrude into latch seat 10A, the armrest <NUM> is in position A. When the movable latch <NUM> is in an angular position so that it can protrude into latch seat 10B, the armrest <NUM> is in position B. When the movable latch <NUM> is in an angular position so that it can protrude into latch seat 10C, the armrest <NUM> is in position C. When the movable latch <NUM> is in an angular position so that it can protrude into latch seat 10D, the armrest <NUM> is in position D.

The latch seat 10D has a smaller depth than the other latch seat 10A-10C. Further the flanks <NUM> of this latch seat 10D are more angled with respect to the radial direction, than the flanks of the other latch seats 10A-10C. This enables that, for transferring the latch into the unlocked state out of latch seat 10D, the bowden cable does not need to be pulled. Solely turning the armrest with a certain amount of force may overcome the spring force. The other latch seats are shaped, so that the unlocked state can solely be reached by pulling the bowden cable.

Based on <FIG> it is described, how the angular position of the armrest is detected. A light feeler <NUM> provides a cone shaped light beam or a scattering light. A reflective plate surface <NUM>, mounted on a ring <NUM> can reflect the light, arriving on the surface <NUM>. Turning the armrest along axis R the ring <NUM> pivots relative to the feeler <NUM>. The reflective surface <NUM> has an inclination in circumferential direction. Thus each angular position is characterized by a specific distance between the feeler <NUM> and the surface <NUM>. The smaller the distance between the feeler <NUM> and the surface <NUM>, the smaller is the amount of reflective light, arriving at the feeler <NUM>. The larger the distance between the feeler <NUM> and the surface <NUM>, the smaller is the amount of reflective light, arriving at the feeler <NUM>. The inclination of the surface <NUM> is shown as a continuous inclination; however a stepwise inclination is also possible, resulting in a smaller angular resolution of the sensor, which is acceptable in this case, because merely an angular resolution of the four positions A-D is requested.

With the help of the optocoupler <NUM> it is detected, whether or not the latch <NUM> is locked in any of the predefined angular positions; with the help of the feeler <NUM> the angular position is determined.

<FIG> shows an exemplary table of allowed conditions referring to the maximum allowed swivel angle. This maximum allowed angle is a function of the armrest position and of the rail position. when the drive assembly is at lower stop position (e.g. section I in <FIG>) the chair can be swiveled by +/-<NUM>° degree. when the drive assembly is in a middle rail section II and the left armrest is in position D, the maximum swivel angle is <NUM>°.

In an alternative embodiment the regulations may be more strict. Here if the armrest is in position D the swivel mechanism and the drive mechanism are always blocked. So before swiveling and driving is allowed the armrest must be brought preferably in one of the positions A,B or at least in in position C.

Claim 1:
Method of controlling a stairlift (<NUM>), the stairlift (<NUM>) comprises
a rail (<NUM>),
a chair (<NUM>),
a drive assembly (<NUM>) having a drive engine (<NUM>) for driving the chair (<NUM>) along the rail (<NUM>),
the chair (<NUM>) is attached to the drive assembly (<NUM>),
the chair (<NUM>) having an armrest (<NUM>), wherein the armrest (<NUM>) is pivotably supported at the chair (<NUM>) by a hinge (<NUM>), which allows a rotational movement of the armrest (<NUM>), in particular along a vertical axis (R),
the method comprising
the step of detecting an angular position (A-D) of said rotational movement of the armrest (<NUM>);
the step of controlling at least one functionality of the stairlift (<NUM>), being a functionality of the drive assembly (<NUM>), as a function of the detected angular position (A-D),
characterized in
the step of checking whether the angular position of the armrest is secured by a locking mechanism,
and the step of controlling a functionality of the drive assembly (<NUM>) is performed additionally as a function of the result of the checking step.