EP0378801A1 - Rolling ladder - Google Patents

Abstract

The ladder comprises a chassis (1) with two pairs of support wheels, of which the two wheels (3) of one pair are mounted on a motorised axle driven by an electromechanical motor reduction gear (4, 5) constituting a brake in the static state. This ladder is guided along a working wall by rollers (12) rolling along a rail (14). The starting and stopping of the motor (5) are controlled by a push-button device (16, 17, 18) disposed within reach of an operator perched on the ladder. The motor (5) is supplied via an electronic circuit housed in a box (19) and comprising means of time-controlling the accelerations and decelerations resulting from the starting and stopping of the ladder. Two automatic stops are provided, one by the ends of travels (28, 29, 30) and the other by a thermal device triggered when the ladder is blocked by an unforeseen obstacle. <IMAGE>

Description

The present invention relates to a rolling ladder comprising support wheels, a device for guiding its movements along a determined path and a braking device for at least one of its support wheels.

This scale is intended to allow punctual interventions in any place of a plurality of work or storage areas distributed in the two directions of a vertical wall such as for example a wall of a telephone exchange distributor, a library or parts storage workshop.

A known rolling ladder of this kind is used to facilitate the maintenance and transformation work of the distributors of certain telephone exchanges.

This ladder comprises a rectangular frame with two pairs of independent wheels surmounted by a double ladder, the two uprights of which have steps and are joined at their upper parts by a platform.

On the distributor side, the frame of this ladder comprises two spaced pairs of rollers with vertical axes applied in each pair on both sides of a horizontal guide rail located at the base of the distributor, all of these elements constituting the guide device. displacements of this rolling ladder along the wall of the dispenser.

On the opposite side to the distributor, this rolling ladder is equipped with a balustrade and a device for braking one wheel of each of the two pairs, with manual control actuated by two substantially horizontal handles located halfway up its two uprights , to assure operator safety when it is perched on it.

It follows from this arrangement that at each change of place of work necessitating a displacement of the rolling ladder, the operator must descend, release the brake and tighten it again before going up on it to the new place of work, after having moved it by simply rolling it, which is already a clear advantage and increased safety compared to handling and the use of a simple conventional ladder.

However, the manipulations of this rolling ladder are still sources of time and fatigue for the operator.

In addition, the manually controlled braking device, essential to immobilize the ladder during the intervention of the operator perched on it, can be a source of danger for him.

Indeed, there is always a probability, as low as it is, that the operator forgets to apply the brake before climbing the ladder, while the probability is zero that he forgets to release it to be able to move it.

Furthermore, even if the brake has been handled correctly, the operator perched on the ladder may accidentally actuate his control handle and loosen it, directly or indirectly, by a tool or an interposed object, for example when moving on the ladder, from one step to another, in the direct environment of this handle.

In both cases, it takes very little to cause the movement of the ladder under the feet of the operator, creating a state of imbalance that can only worsen by wanting to catch up, all the conditions being thus met to cause a fall.

The object of the invention is to increase the safety of the operator and to facilitate his work, by overcoming the aforementioned drawbacks.

To this end, the rolling ladder according to the invention is characterized in that it comprises an electro-mechanical motor-reduction unit direct drive of at least one of its support wheels, in both directions of rotation thereof, and a device for controlling actuation of the starting in the two directions mentioned above and of stopping the motor-reduction unit, comprising at least one actuation command by press-buttons, the buttons are provided accessible in all positions from an operator perched on the scale and an electronic circuit for automatic delay of the durations of acceleration and deceleration of the scale consecutive respectively to the actuations of the start and the engine-reduction unit shutdown.

In this way, the operator no longer has to go down the ladder to move it from one workplace to another, he just has to press the buttons on the start and stop command. of the motor-reduction unit which are within its reach; there is no longer any probability that he forgets to apply the brake before climbing up on the ladder or to accidentally release it once perched on it, since the braking device is here constituted by an engine brake system, due to the direct drive of the drive wheel by the motor-reduction unit.

Finally the ladder starts and stops smoothly, without jerks which can cause a loss of balance, thanks to the delay of the acceleration and deceleration durations consecutive to these actions, this delay being adjusted for this purpose.

From this basic design, developments can be made, with the effect of increasing safety for the operator and the equipment.

Thus, in a particular embodiment of the control device for actuating the starting and stopping of the motor-reduction unit, this device also comprises an automatic stop control connected to the electronic circuit. timer and actuated by at least one limit switch, the movable member of which is placed so as to be acted upon by a fixed limit stop positioned in front of and close to each end of the course of the determined path of the scale , in both directions of movement thereof.

As a result, any risk of undesirable overshooting of the planned path of the ladder following an oversight by the operator to actuate the stop control button is avoided, as well as that of a sudden stop against a natural limit of this path, such as for example a partition or a wall.

In another particular form of the control device for actuating the starting and stopping of the motor-reduction unit, this device also comprises an automatic stop control actuated by a member for detecting the magnitude of the torque. motor set to trip when a predetermined value of said quantity is exceeded.

Therefore, it is possible to cause the motor-reduction unit to stop when it meets the ladder with a unforeseen obstacle, such as for example a case of equipment or tools heavy enough to stop it, by adjusting the detection member to a value of engine torque for example less than the maximum critical value for the equipment.

• La figure 1 en est une vue d'ensemble.
• La figure 2 est un schéma fonctionnel de son dispositif de commande.

The accompanying drawing shows, by way of example, an embodiment of the subject of the invention.

• Figure 1 is an overview.
• Figure 2 is a block diagram of its control device.

The rolling ladder shown in Figure 1 is shown from the side of a working wall, not shown, such as for example that of a telephone exchange distributor.

This ladder comprises a chassis 1 of rectangular shape equipped at one end with two independent support wheels 2 and at the other end with an axle with two dependent support wheels 3 driven in rotation, in both directions and directly, by the output member of a reducer 4 of an electro-mechanical 5-reducer motor group 4 fixed to the chassis 1.

The reduction gear 4, the output member of which can be, for example, the wheel of a worm gear whose screw is mounted on the motor shaft 5, is chosen so as to constitute, when the supply of the latter, the ladder braking device, the speed of rotation of the motor 5, the reduction ratio of the reduction gear 4 and the diameter of the wheels 3 being determined for this purpose in relation to the mass displaced and the speed maximum desired scale displacements.

The ladder proper comprises two uprights 6 and 7 inclined towards one another, bearing on the two ends of the chassis 1, joined at their upper parts by a platform 8 and comprising steps 9 in the manner of '' a staircase to make the operator's work easier at all levels.

On the external side opposite the working wall, this ladder comprises a balustrade 10 carrying at its upper end a service shelf 11.

On the side of the working wall, the chassis 1 has two spaced pairs of cylindrical rollers 12 with vertical axes supported in offset positions by two brackets 13. The two rollers 12 of each pair are applied against the two opposite sides of a guide rail 14 located at the base and along the working wall and supported by brackets 15 partially shown, fixed to said wall, this set of means constituting the device for guiding the movements of the rolling ladder along its path.

The starting of the motor 5 in its two directions of rotation, and its stopping, are controlled by a control device whose functional diagram is represented in FIG. 2 and of which certain components are visible in FIG. 1.

This device comprises a manual control by press-buttons and an electronic circuit for automatic delay of the durations of acceleration and deceleration of the ladder consecutive respectively to the actuations of the starting and stopping of the motor-reduction unit. .

The manual control 16 by press-button has two buttons 17 and 18, differentiated for example by their colors, which each control the start-up and stopping the supply of the motor 5, one 17 for one direction and the other 18 for the other direction of its rotation, the starting being triggered by pressure, and the stopping by releasing the respective button.

In FIG. 1, three control boxes 16 of this kind are distributed respectively on the two sides and on the upper part of the balustrade 10 at levels provided so that the operator perched on the ladder can easily reach them in all positions of work.

The electronic circuit for automatically delaying the times of acceleration and deceleration of the scale, contained in a box 19 fixed to the chassis 1, comprises:
three setpoint members 20, 21 and 22, constituted for example by potentiometers, by which the duration of the acceleration, the duration of the deceleration and the maximum speed of rotation of the desired motor 5 are displayed,
a comparison and control unit 23 to which the aforementioned instructions are connected as input quantities and through which the motor 5 is supplied with an input voltage u, by means of a module 24 power transistors,
a processor 25 connected to the comparison and control unit 23, programmed for processing the output quantities of this unit,
a control circuit 26 for the power transistors of the module 24, the output of which is connected to the latter and the input of which is connected to the processor 25,
- and a unit 27 for detecting the output quantities motor 5, acceleration, deceleration and rotational speed, connected, to transmit the signals f corresponding to these quantities and for feedback to the comparison and control unit 22.

The source of the electric power supply current for the motor 5 and its control circuit, not shown, consists for example of the mains current, of voltage u, transmitted from a contact rail extended parallel to the guide rail 14 along of the working wall and by means of a contact carriage driven by the ladder in its movements.

It is also possible to use a rechargeable accumulator installed on the chassis 1 next to the housing 19 to supply this voltage u.

In this embodiment given as an example, the device for controlling the actuation of the starting and stopping of the motor-reduction unit further comprises:
a first automatic stop command for the motor 5, connected to the electronic circuit for delaying acceleration and deceleration, actuated here by two limit switches 28 fixed to the chassis 1 and whose movable member 29 is placed so as to be acted upon by a limit stop 30 positioned in front of and close to each end of the path of the ladder path in both directions of its movement, of which only one is visible on the left side, fixed to a console 15,
- A second automatic engine stop command 5 actuated by a detection member 31 of the magnitude of the engine torque, such as for example a thermal, set to trigger when a predetermined value of said magnitude is exceeded.

Restarting, in the event of a trip caused by this second automatic stop command, is done by actuating a main switch, not shown.

Thanks to this arrangement, the rolling ladder according to the invention provides good operator safety and facilitates his work by making it possible to do it more quickly.

By the motorization and its on-off control by button presses 16, 17 and 18 always within reach, the operator perched on the ladder goes where he wants along the work wall without having to descend the ladder to move it.

The motor-brake system provided by the type of movement transmission by the worm gear wheel 4, associated with the press-button system by pressure and release, provides excellent safety in the sense that the operator is obliged to maintain the control button pressed for during the movement of the ladder, that is to say in fact in a position of good balance by restraint at the balustrade, and only when this button is released and after stopping the ladder, it cannot be made free to roll.

The automatic delay of the acceleration and deceleration times means that the ladder starts and stops are smooth, and the display of the quantities which govern these phenomena by means of potentiometers 20, 21 and 22 allows them to be modulated. at will as needed.

The first automatic stop command by a limit switch system 28, 29 and 30 frees the operator from the attention which he must pay to each arrival of the ladder at the ends of his journey, to command his stop.

Finally, the second automatic stop command by detection of a limit quantity of the motor torque makes it possible to cause the motor 5 to stop when it meets the ladder with an unforeseen obstacle sufficiently heavy to stop it before any deterioration of the equipment, especially by overheating of the electrical circuit.

The last two automatic stop commands, although interesting in terms of the additional security they provide, the first for the operator and the second for the equipment, are however not essential in view of the aforementioned advantages already obtained with the motorization with timed starts and stops.

Of course, variants may be made without departing from the scope of the invention, in particular in the arrangement of the control circuit for actuating the starting and stopping of the motor-reduction unit and in that of the circuit. time delay electronics for which other means with equivalent effects may be used.

With regard to the engine brake system, it is also obvious that any reduction system other than by wheel and worm can be applied, to the extent of obtaining an equivalent effect.

Claims (3)

1. Rolling ladder comprising support wheels, a device for guiding its movements along a determined path and a braking device for at least one of its support wheels, characterized in that it comprises an electro-mechanical direct-drive unit (4, 5) for direct drive of at least one of its support wheels, in both directions of rotation thereof, and a device for controlling actuation of the starting in the two aforementioned directions and of stopping the motor-reduction unit, comprising at least one actuation command by press-button (6) whose buttons (7, 8) are provided accessible in all positions of an operator perched on the scale and an electronic automatic timing circuit (20 - 27) of the times of acceleration and deceleration of the scale consecutive respectively to the actuations of the start and stop of the motor-reduction unit. 2. Rolling ladder according to claim 1, characterized in that the control device for actuating the starting and stopping of the motor-reduction unit further comprises an automatic stop command connected to the electronic time delay circuit. and actuated by at least one limit switch (28), the movable member (29) of which is placed so as to be biased by a fixed limit stop (30) disposed in front of and close to each end of the course of the ladder path, in both directions of its displacements. 3. Rolling ladder according to claim 1, characterized in that the control device for actuating the starting and stopping of the motor-reduction unit further comprises an automatic stop command actuated by a detection member. (31) of the magnitude of the engine torque set to trip on exceeding a predetermined value of said quantity.

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