Elevator – industrial lift truck – or stationary lift for vehicle – Stairway assist for individual or minor barrier lift for... – Mounted adjacent stairway for travel parallel thereto
Patent
1996-05-28
1998-02-24
Noland, Kenneth
Elevator, industrial lift truck, or stationary lift for vehicle
Stairway assist for individual or minor barrier lift for...
Mounted adjacent stairway for travel parallel thereto
187245, B66B 908
Patent
active
057203644
DESCRIPTION:
BRIEF SUMMARY
This invention relates to stairlifts and more particularly to an arrangement for maintaining the seat of a stairlift level as its carriage moves along a rail of varying angle of inclination.
In some stairlift installations, the rail is able to maintain a constant angle of inclination: in these cases, the seat remains at a constant angle relative to the carriage of the stairlift. Often however, the stairs do not rise at a constant rate, for example where the stairs include a landing: in these cases it is necessary for the angle of the seat, relative to at least part of its carriage, to be changed as the carriage moves along the rail, so as to keep the seat level. Hitherto, this has been achieved mechanically, the seat being pivotally mounted to the carriage and coupled to a lever which follows a guide bar fixed to the main rail of the stairlift: the location of the guide bar on the rail controls the angle of the lever and accordingly the angle of the seat. The location of the guide bar on the rail, at different positions along its length, is therefore critical to ensure that the seat will remain level, and therefore the rail and its guide bar must be tailored to each individual installation.
We have now devised an arrangement which overcomes the problem which has been set out above.
In accordance with this invention, there is provided a stairlift comprising a carriage for movement along a fixed rail, a seat pivotally mounted to the carriage, an actuating means for turning the seat relative to its carriage, and control means responsive to the position of the carriage along its rail and to stored data representing the desired angle between the seat and carriage at different positions of the carriage along the rail, to control the actuating means so as to maintain the seat substantially level.
Preferably the actuating means for turning the seat relative to its carriage comprises an electric motor. Preferably this motor is included in a closed-loop servo control.
Preferably the control means determines the linear position of the carriage along its rail from a count related to the turns made by a drive motor of the carriage: typically this motor drives a pinion wheel meshed with a toothed rack provided along the rail.
Preferably the control means is arranged to make linear interpolations between successive items of the stored data, to provide an uninterrupted demand signal to the seat levelling motor.
Preferably a safety arrangement is provided, which responds to the seat tilting, relative to the carriage, to more than a predetermined angle, to lock the seat to the carriage. The arrangement may comprise a pin which is spring-biassed to extend through a locating aperture of the seat, but is normally held retracted by a solenoid the circuit to which includes a pair of opposite tilt switches.
Preferably a controller is provided, for preprogramming the control means of the stairlift with its data representing the desired seat-to-carriage angle at different linear positions of the carriage along its rail. In use of this controller, the carriage is moved to successive points along the rail and, at each point, the seat is levelled via the controller and then the corresponding linear position and seat-to-carriage angle are written into memory.
Alternatively or in addition, the control means may include an auto-calibration facility, including means to self-level the seat at successive points along the rail, and then write the corresponding linear position and seat-to-carriage angle into memory.
An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which:
FIG. 1 is a diagrammatic side view of the carriage of a stairlift mounted to its fixed rail;
FIG. 2 is a diagram of a closed-loop servo control for a seat levelling motor of the stairlift; and
FIG. 3 is a schematic diagram of a control system of the stairlift, including a preprogramming controller for the linear position and seat-to-carriage angle data.
Referring to FIG. 1, there is shown a stairl
REFERENCES:
patent: 4811226 (1989-03-01), Shinohara
patent: 5230405 (1993-07-01), Bartelt
Noland Kenneth
Schindler Edwin D.
Stannah Stairlifts Limited
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