WO2014098574A1

WO2014098574A1 - Stair lift drive

Info

Publication number: WO2014098574A1
Application number: PCT/NL2013/050895
Authority: WO
Inventors: Rolf Bernard DE JONG; Cornelis BOXUM; Gijs Jan Jacobs MULDER
Original assignee: Thyssenkrupp Accessibility B.V.
Priority date: 2012-12-19
Filing date: 2013-12-12
Publication date: 2014-06-26
Also published as: EP2935073A1; CN104995118A; NL2010013C2; CN104995118B; JP2016505468A

Abstract

The present invention relates to a stair lift drive, comprising a rail extending along a track, a first frame part, provided with at least one pair of wheels engaging the rail, a second frame part, provided with at least one pair of wheels engaging the rail, a propulsion, to drive at least one of the wheels, a mounting part for a seat of a user of the stair lift, connected to the first frame part; wherein the first frame part is freely rotatably connected to the second frame part about two axes, which are perpendicular to each other and perpendicular to the tangential direction of the track; and about an axis parallel to the tangential direction of the track.

Description

STAIR LIFT DRIVE

The present invention relates to a drive for a stair lift. In particular, the invention relates to a stair lift drive, which consists of two frame parts, which are freely rotatable with respect to each other.

It is known in the state of the art to drive a stair lift over a rail that extends along a staircase. L 2005398 for instance discloses a friction drive for a stair lift along a longitudinal guide, wherein multiple rollers are in frictional engagement with the rail. Such drives for stair lifts are designed to propel a stair lift over a meticulous constructed rail along a staircase. However, one of the disadvantages of the above state of the art is that the stair lift disclosed is not suitable for (sharp) curves in the, which may be required to follow the outlines of a staircase naturally. It is therefore the goal of the present invention to overcome these drawbacks, or at least to offer a suitable alternative.

The invention thereto proposes a stair lift drive, comprising a rail extending along a track, a first frame part, provided with at least one pair of wheels engaging the rail, a second frame part, provided with at least one pair of wheels engaging the rail, a propulsion, to drive at least one of the wheels; a mounting part, for mounting a carrier for a load such as a seat for a user of the stair lift, connected to the second frame part; wherein the first frame part is freely rotatably connected to the second frame part about two axes, which are perpendicular to each other and perpendicular to the tangential direction of the track, and about the tangential direction of the track or about an axis parallel to the tangential direction of the track.

It is to be noted here that the above mentioned mutual orientations are to be regarded when the stair lift drive according to the invention is on a straight part of the track.

The stair lift according to the invention provides the advantage that the two frame parts, comprising driving wheels, are freely rotatable and moveable in multiple directions with respect to each other. The frame parts serve as bogies and enable the stair lift to move along curved and twisted rails. The bogie function is to enable movement of the drive along a curved and/or twisted track.

The mounting part for the seat of the stair lift may be connected rigidly to the second frame part, wherein the first frame part serves for delivering additional driving force. Because the two frame parts can rotate freely with respect to each other, the first and second frame parts can follow each other easily around corners, twists and bends.

The mounting part can be rigidly connected to the second frame part as described above, but it may also have rotational freedom in predetermined directions. The rail along which the stair lift propels itself may preferably be a smooth rail provided with one or more recesses along its length. A mounting part rigidly connected to the first frame part leads to a relatively simple construction, and also serves to create a stable platform, resembling a bogie together with the second frame part. However, this construction is dividing the load depending on inclination angle, centre of gravity (cog) and/or stiffness of construction over the first and the second frame part.

Therefor, in a further embodiment of the present invention the mounting part is freely rotatably connected to the second frame part about two axes, which are perpendicular to each other and perpendicular to the tangential direction of the track and the mounting part is rotatably connected to the second frame about the tangential direction of the track.

In another embodiment of the present invention the mounting part is connected to the first frame part by a first bracket, wherein the connection between the mounting part and the first carries comprises a first of the rotation axes, and the connection between the first bracket and the first frame part comprises a second of the rotation axes and wherein the mounting part is connected to the second frame part by a second bracket, wherein the connection between the mounting part and the second bracket comprises a first of the rotation axes, and the connection between the second bracket and the second frame part comprises a second of two rotation axes. The brackets form a well proven practical embodiment comprising the above mentioned axes of rotation, and allow a geometrically spread position of orthogonal axes of rotation being a robust construction. In yet another embodiment the rotational axis of a frame part in the direction of the y- axis (see figure 1 below) cuts a vector representing the direction and position of the resulting traction force. The same may go, in further embodiments, for the rotational axis of a frame part in the direction of the z-axis.

In an embodiment with two dents in the rail the resulting force coincides with the axial axis (centre line) of the rail if both wheels are powered. If only one of the wheels is powered, the resulting force is parallel to but not coincident with the axis (centre line) of the rail, and the rotational axis of a frame part in the direction of the y-axis is eccentric as well.

In another embodiment the actuator is powered depending on the weight applied to the seat by the user of the stair lift and/or is depending on the inclination angle of the track and/or is depending on the orientation of the first frame part to the second frame part . The higher the weight of a user to be transported and/or inclination angle of the rail track and/or difference in orientation between both frame parts, the higher the required traction force by the wheels on the track. On the other hand, a higher normal force leads to a higher rolling resistance, so keeping the traction force and therefore also the normal force pressing the friction wheels at the required minimum is an aim. For example driving on a horizontal track and/or applied with a relative light user weight requires a relative low traction force, visa versa for heavy users and/or high inclination angles. Also a controlled normal force depending on weight and/or inclination angle is also lowering wear and fatigue. Thereto, a seat may be mounted on the mounting part, in such way that it can be impressed by the weight of a user taking place on the seat and/or is actuated by the inclination angle of the track, wherein a hydraulic cylinder is coupled between the seat and the mounting part, for providing hydraulic pressure dependent on and proportional to a weight of a user taking place on the seat and/or to the inclination angle of the track, which cylinder is coupled hydraulically to the hydraulic actuators for moving the first wheel towards the second wheel of a pair of a drive.

In an embodiment of the present invention the stair lift drive comprises at least two wheels that are movable towards and from the rail, each applied to a different frame part, and each frame part provided with two wheels with propulsion being either with the same rotational speed or with substantially equal torque. An equal torque will, in order to prevent minimise slip in curves and as a result have evenly distributed torque over both friction wheels, providing maximum efficiency from the applied normal forces allowing maximum traction force.

In an embodiment the drive can also be provided with one motor per frame part where both drive wheels are connected by gear wheels with ratio 1 : 1, resulting in equal rotational speed of both wheels. This has the advantage of reducing cost. Disadvantage is not having an optimum torque distribution between both friction wheels when driving through curves and twists.

In another embodiment the drive can also be provided with one motor per frame part where both driven wheels are connected by mechanical differential. This has the advantage that torque is substantially evenly distributed over both friction wheels and reducing the frame part with one motor and so reducing cost.

In a further embodiment, the stair lift drive is provided with a control system, which aims to gain as much traction as possible from the friction wheels. Ideally the traction forces of all wheels within one frame part are equal. Minimizing the negative effects due to slip and applying the maximal torque on all friction wheels is accomplished when the control system distributes the torque substantially equal over all driven wheels. This can be done by measuring current through the drive of each wheel and by controlling it to a speed-set point and/or voltage and/or current specific for each one of the friction wheels, which may be specific for each of the wheels. The set-points may in particular be chosen such that distances in length for inner and outer radius of curves are taken into account, so that slip is minimised or even fully prevented.

Besides controlling the traction force between separate wheels of one single frame part, the controller may further be configured to control two frame parts to share total needed torque as evenly as possible over all drive wheels..

In another embodiment of the invention the frame part comprises a pair of stabilising wheels or gliders, which engage the rail respectively on the top and bottom side. The pair may be in front of or behind the driving wheel in a driving direction, or multiple pairs may be applied. These wheels or gliders may be movably connected to the first or second frame part by means of a sub frame that is movable with respect to the first or second frame part, to allow the wheels or gliders to follow curves in the rail. The sub frames may comprise spring elements to force the wheels or gliders to the rail with a bias. In another embodiment the first and/or second sub frame part is movable with respect to respectively the first or second frame part by means of an actuator.

In a further embodiment the first and/or second frame part comprises a sensor to measure an angular rotation of the frame part about an axis perpendicular to the axial direction of the rail and perpendicular to the direction from the front to the back of the rail, and to issue a sensor signal representing the angular rotation. Such sensor may be configured to scan or explore the rail when the drive is moving. The sensor signal may be used to control the drive and to correct angular movement. The first and/or second frame part may thereto comprise two independently drivable wheels, which are each applied on either side of the rail, and wherein the propulsion comprises a controlling device to control the independently drivable wheels, depending on the sensor signal, such that each time, they are located on the rail exactly opposite to each other. The invention will now be elucidated into more detail with reference to the following figures, wherein:

- Figure 1 shows the coordinate system as generally used to indicate movements;

- Figure 2 shows a z-stabilizer with sliding guiding elements;

- Figures 3a-d show guiding elements able to translate;

- Figures 4a, b show sliding guiding elements;

- Figures 5a, b shows a spring loaded roller construction of a z-axis stabilizer construction;

- Figures 6a, b show a drive unit, with a set of two rail following elements; and

- Figure 7 shows a drive unit with two rail measuring arms.

Figure 1 shows the coordinate system as generally used to indicate movements. In order to designate the orientation of a drive with respect to a rail, a system of coordinates is used. The x-axis is the local tangent to the centerline of the rail. For the rotation around the x, y and z axes the navigational and aviational terms pitch, yaw and roll are used respectively. Note that the drive moves in the direction of the x-axis, unlike vessels and planes, which move in the direction of the z-axis. In other words, the drive moves sideways.

In the figure, the reference numbers indicate the following:

101 Right

102 Pitch

103 Yaw

104 Longitudinal

105 Roll

106 Vertical

107 Lateral Left Figure 2 shows a z-stabilizer with sliding guiding elements, whose translation in the direction of the y-axis is obtained by means of a hinging construction. The figure shows a rail 1 extending along a track, a first or second frame part 2, 3, provided with at least one pair of wheels (A and B) engaging the rail; a propulsion 4, 5, to drive at least one of the wheels and a pair of stabilising gliders 24, 25, which engage the rail respectively on the top and bottom side. The pair of gliders may be in front of or behind the driving wheel (A and/or B) in a driving direction, or multiple pairs may be applied. These wheels or gliders may be movably connected to the first frame by means of a frame section that is movable with respect to the first or second frame part, to allow the wheels or gliders to follow curves in the rail

Figures 3a, b show guiding elements able to translate in the direction of the y-axis with convex rail sections (3a) and concave rail sections (3b). The pair of gliders 24, 25 may be in front of or behind the driving wheel (A and/or B) in a driving direction, or multiple pairs may be applied. These wheels or gliders may be movably connected to the first or second frame part 2, 3 by means of a frame section 26 that is movable with respect to the first or second frame part, to allow the wheels or gliders to follow curves in the rail 1, as visible in figures 3c, 3d. Figures 4a, b show an alternative embodiment and shows a construction with sliding guiding elements 27, mounted on hydraulic cylinders 28. These cylinders are crosswise connected to each other, so a downward translation of the left-under guiding element goes together with a downward translation of the upper right cylinder, and so on.

Figures 5a, b show an alternative embodiment of a z-stabilizer construction by means of a pair of stabilising wheels 29 at one side of the drive unit, which engage the rail respectively on the top and bottom side. The wheels can follow curves in the rail through spring means 30. The expectation is that the behaviour is different from the previous constructions and possible have a positive effect on twisted rail sections.

Figures 6a, b show a first or second frame part 2, 3, which is equipped with a set of two rail-tangent following elements 32. These elements are connected to a rail tangent following frame 33 by means of a spring element 34. The spring element presses the rail tangent following elements into the recess of the rail 1. Since the rail tangent following frame can rotate around the y-axis of the frame part, its orientation will follow the tangent to the rail's centreline. The rail tangent following frame is connected to an angle sensor 35, whose axis is connected to the y-axis of the frame part. Thus, when the z-axis of the drive unit is not perpendicular to the rail's centreline tangent, this will result in a changed value from the angle sensor.

Figure 7 shows a frame part 2, 3, which is equipped with two rail-distance measuring arms 36, which can rotate independently from each other around a common shaft 37. The rail distance measuring arms are each equipped with a rotatable sliding element 38 which is pressed against the front or back side of the rail 1, due to pre-tensioning element (not shown here) which is mounted on the rail distance measuring arms. The rotation of each measuring arm is measured with an angle sensor 39. Thus, when the z- axis of the drive unit is not perpendicular to the rail's centreline tangent, this will result in different values from the angle sensors.

All features of the present invention can be combined with the features disclosed in the same dated Dutch patent applications "Stair lift drive for a smooth dented rail" and "Stair lift drive with rotatable mounting part for seat" by the applicant which are incorporated by reference

Claims

1. Stair lift drive, comprising:

- a rail extending along a track;

- a first frame part, provided with at least one pair of wheels engaging the rail;

- a second frame part, provided with at least one pair of wheels engaging the rail;

- a propulsion, to drive at least one of the wheels;

- a mounting part, for mounting carrier for a load such as a seat for a user of the stair lift, connected to the first frame part; wherein

-the first frame part is freely rotatably connected to the second frame part about two axes, which are perpendicular to each other and perpendicular to the tangential direction of the track; and about an axis parallel to the tangential direction of the track.

2. Stair lift drive according to claim 1, wherein

- the mounting part is freely rotatably connected to the second frame part about two axes, which are perpendicular to each other and perpendicular to the tangential direction of the track; and

-the mounting part is rotatably connected to the second frame about the tangential direction of the track.

3. Stair lift according to claim 2, wherein

-the mounting part is connected to the first frame part by a first bracket, wherein the connection between the mounting part and the first carries comprises a first of the rotation axes, and the connection between the first bracket and the first frame part comprises a second of the rotation axes; and

-wherein the mounting part is connected to the second frame part by a second bracket, wherein the connection between the mounting part and the second bracket comprises a first of the rotation axes, and the connection between the second bracket and the second frame part comprises a second of two rotation axes.

4. Stair lift drive according to any of the preceding claims wherein the rotational axis of a frame part in the direction of the y-axis or z-axis cuts a vector representing the direction and position of the resulting traction force.

5. Stair lift drive according to any of the preceding claims, provided with a control system, which is configured for measuring current through a drive of each wheel and for setting a speed-setpoint (substantially) equal for all driven wheels.

6. Stair lift drive according to claim 5 wherein the set-points are chosen such that distances in length for inner and outer radius of curves are taken into account, so that slip is minimised or even fully prevented.

7. Stair lift drive according to claim 5 or 6, wherein the controller is further configured to control two frame parts to have equal force.

8. Stair lift drive according to any of the preceding claims, comprising at least two wheels that are movable towards and from the rail by means of an actuator, wherein the actuator is powered depending on the required traction, depending on variables such as the weight applied to the seat by the user of the stair lift and/or inclination angle of the track.

9. Stair lift drive according to any of the preceding claims, comprising a pair of stabilising wheels or gliders, which engage the rail respectively on the top and bottom side.

10. Stair lift drive according to claim 9, wherein the wheels or gliders are movably connected to the first or second sub frame part with respect to respectively the first or second frame part.

11. Stair lift drive according to claim 10, wherein the first and/or second sub frame part is movable with respect to respectively the first or second frame part by means of an actuator.

12. Stair lift drive according to any of the preceding clams, wherein the first and/or second frame part comprises a sensor to measure an angular rotation of the frame part about an axis perpendicular to the axial direction of the rail and perpendicular to the direction from the front to the back of the rail, and to issue a sensor signal representing the angular rotation.

13. Stair lift drive according to claim 12, wherein the first and/or second frame part comprises two independently drivable wheels, which are each applied on either side of the rail, and wherein the propulsion comprises a controlling device to control the independently drivable wheels, depending on the sensor signal, such that each time, they are located on the rail exactly opposite to each other.

14. Stair lift drive according to claim 12 or 13, wherein the propulsions for driving the wheels of the first and second frame part are arranged in a master-slave setup.

15. Stair lift drive according to claim 12 or 13, wherein the propulsions for driving the wheels of the first and second frame parts are arranged in a symmetrical setup.