Title:
STOREY SELECTOR DEVICE FOR LIFTS
United States Patent 3752264


Abstract:
A storey selector device for elevators and the like has a number of destination selector switches for different stopping levels which connect different tappings of a fixed resistance to one end of a sensing diagonal of a Wheatstone bridge, the other end of the sensing diagonal being connected to the slider of a potentiometer controlled by movement of the elevator carriage. The sensing diagonal incorporates unidirectional conductive elements responsive to imbalance currents in opposite directions to control movement of the elevator motor in opposite respective directions to bring the elevator carriage to the selected destination level.



Inventors:
CHIAPELLA R
Application Number:
05/190159
Publication Date:
08/14/1973
Filing Date:
10/18/1971
Assignee:
CHIAPELLA R,IT
Primary Class:
International Classes:
B66B1/16; (IPC1-7): B66B1/16
Field of Search:
187/29 318
View Patent Images:



Primary Examiner:
Gilheany, Bernard A.
Assistant Examiner:
Duncanson Jr., W. E.
Claims:
I claim

1. Movement preselection device for elevators having a moving carriage, comprising in combination:

2. Movement pre-selection device according to claim 1, wherein said switches are operable from each stopping

3. Movement preselection device according to claim 13, wherein said control means in said arm means is formed by two parallel branches containing respective unidirectional circuit elements of opposite polarity for discriminating the direction of current in the sensing diagonal to control said carriage drive means to move said carriage selectively in opposite respective directions.

4. Movement pre-selection device according to claim 3, wherein said unidirectional circuit elements are diodes.

5. Movement pre-selection device according to claim 3, wherein said unidirectional circuit elements comprise transistors of complementary types.

6. Movement pre-selection device according to claim 1, wherein said control means for the driving means includes power amplification means.

7. Movement pre-selection device according to claim 1, wherein the potentiometer is formed by a metal cable anchored to the carriage for movement therewith and an intermediate contact connected electrically to said cable and secured to a part of the fixed installation of the elevator or.

8. Movement pre-selection device according to claim 7, wherein said intermediate contact is formed by a pulley around which said cable passes.

9. Movement pre-selection device according to claim 7, wherein said metal cable is the operating cable of a speed limiter of said elevator to elevator.

10. Movement pre-selection device according to claim 7, including a connecting element secured to the elevator carriage and means securing the ends of said metal cable to and electrically insulated said ends from said connecting element, the direct voltage supply being connected across said two ends of said cable.

11. Movement pre-selection device according to claim 1, wherein said potentiometer is formed by a metal wire extending longitudinally in the space in which said elevator carriage moves, means anchoring and electrically insulating the ends of said wire, and a sliding contact in contact with said wire and fixed to the conveyor carriage, the direct voltage supply being connected across said ends of said wire.

12. Movement pre-selective device according to claim 1 including an auxiliary circuit maintaining the operation of said carriage drive means after de-energisation of said control means, and means operable directly by the elevator carriage to break said auxiliary circuit upon arrival of said carriage at the pre-selected destination point.

Description:
BACKGROUND AND OBJECTS OF THE INVENTION

This invention relates to a movement pre-selection device for elevators, conveyors and the like, that is, a device for pre-selecting automatically the direction of movement of an elevator or conveyor and the point at which it is to stop. The invention is applicable in particular to electrically controlled machinery for moving elevators and conveyors, including passenger elevators and service or goods elevators, cranes, carriers, filing systems, access platforms and the like.

Movement pre-selection devices of the above-mentioned type, as used for example as a storey selector device for an elevator, control the direction of movement of the elevator motor and also recognize the destination station of the elevator so that when the destination is reached the elevator motor stops automatically.

In earlier movement pre-selection devices three-position switches, were positioned at each stopping point and were arranged to be operated by slides carried by the moving carriage of the elevator or conveyor. Such an arrangement necessitated electrical wiring in the space in which the carriage moves, for example, an elevator shaft, involving complicated and time-consuming installation work, difficulties in maintenance and susceptibility to mechanical and electric deterioration. The placing of switches at the various stopping points made control difficult because of the relative inaccessibility of such switches. Furthermore such switches were generally noisy in operation.

In order to avoid, at least to some extent, the above-mentioned drawbacks, the switches have been grouped successively in the space in which the carriage moves and controlled by transmission means such as ropes or chains, with suitable amplification. Such arrangements were also prone to mechanical or electrical deterioration, and required precision manufacture and installation, making the device expensive. Moreover, small variations of position of the movement control mechanism and associated contacts, due to deterioration or adjustment, caused error in the carriage stopping positions, to a degree which was made worse by the movement amplification. A further drawback of such movement pre-selection devices was the impossibility of installing them on elevators or conveyors having lower machine spaces, as it was necessary to install the stopping point selectors in positions easily reached by the movement transmissions member and it was also necessary to join the electrical selector panel in the elevator or conveyor carriage to the selectors with suitable electrical connections.

A further evolution of the selective device in which all the switches for the various stopping points were installed in the machinery space gave rise to the use of contacts operable by electro-magnets or small motors energised in turn as the carriage passed each stopping point by one or more electrical contacts carried by the carriage, and by slides and magnetic screens placed at the various stopping points. Such devices are, however, expensive to maintain, are still prone to mechanical and electrical failure and deterioration because of the essentially electro-mechanical nature of their operation, require frequent maintenance, and in addition have the disadvantage of requiring two rephasing contacts at the ends of the run in order to correct the phase discrepancy which often arises between the effective positions of the carriage and the position shown by the selector. Such rephasing contacts require the placing of electric cables in the space in which the carriage moves.

One of the main objects of this invention consists in the provision of a movement pre-selection device for elevators, conveyors and the like which does not require the installation of electrical cables or electrical contacts in the space in which the carriage moves.

A further object of this invention is the provision of a movement pre-selection device of the above-mentioned type without moving parts which does not therefore require maintenance or suffer appreciable mechanical and electrical deterioration.

Another object of this invention is the provision of a movement pre-selection device of the above-mentioned type, made of materials which are of relatively low cost and which are commercially available, and without requiring specially made metal or plastics parts.

Similarly, another object of this invention is the provision of a movement pre-selection device of the above-mentioned type, the installation and running costs of which are lower than those of previously known devices.

Yet another object of this invention is the provision of a pre-selection device of the above-mentioned type which is silent in operation.

Further objects of the invention include the provision of a pre-selection device of the above mentioned type in which each pre-selectable stopping position of the carriage is not influenced by deterioration or wear of parts of the pre-selection device itself; in which the carriage remains in phase with the device, avoiding the need for phase correction after each carriage movement, and in which independent controls are included at each stopping position for controlling movement of the carriage in opposite directions.

According to the invention there is provided a movement pre-selection device for elevators, conveyors or the like, characterised in that the device includes a Wheatstone bridge having a direct voltage supply between which a fixed resistance and a potentiometer controlled by the elevator or conveyor are connected in parallel, selector switches for each stopping point of the elevator or conveyor connected to respective tappings of the fixed resistance, and a sensing diagonal arm of the bridge between the selected switch and the sliding contact of the potentiometer, the sensing diagonal arm forming a control circuit responsive to current flow in the sensing diagonal in opposite directions to control the elevator or conveyor drive means so as to move the elevator or conveyor in opposite respective directions.

The potentiometer may be formed by a metal cable pulled by the movement of the elevator or conveyor carriage. This metal cable may be the operating cable of the speed limiter of said elevator or conveyor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described and illustrated, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic circuit diagram of a movement pre-selection device according to the invention, as applied to an elevator;

FIG. 1a is a side view of part of a device according to one embodiment of the invention;

FIG. 2 is a side view of part of an elevator installation having a movement pre-selection device according to another embodiment of the invention;

FIG. 3 is an electrical circuit diagram of an elevator installation with three stopping levels and a level pre-selection device having switches at the various stopping levels of the previously known type, and

FIG. 4 is an electrical circuit diagram of an elevator installation with three stopping levels having a level pre-selection device according to this invention.

FIG. 1 shows schematically an electric circuit of a movement pre-selection device for elevators and like conveyors according to this invention. A direct supply voltage +V, -V is connected in parallel, across a potentiometer wire 10 having a sliding contact 12 and across a potential divider having a fixed resistance 14 and tappings 15-0, 15-1, 15-2, 15-3, 15-4, equal in number to the number of stopping levels which the elevator or conveyor is to serve. Each tapping 15 is connected to a respective switch 16-0, 16-1, 16-2, 16-3, 16-4 for each level. Closure of one of the switches 16, which are operable from any of the stopping points, inserts between the selected tapping 15 and the sliding contact 12 a relay circuit, represented schematically, formed by two parallel branches, each of which includes a relay S, D in series with a respective diode 18, 20.

The circuit constitutes a Wheatstone bridge in which each level selector switch 16 is effective to select a different resistance ratio in the ratio arm constituted by the potential divider 14, 15. The sliding contact 12 of the potentiometer 10 is associated with the carriage of the elevator or conveyor, so that the actual position of the carriage determines the position and therefore the potential of the sliding contact 12.

The diodes 18 and 20 are connected in opposition, so that the current passes only through the relay D or only through the relay S, according as the potential at the contact 12 is respectively higher or lower than that at the selected tapping 15.

With a suitable choice of the resistances between the various tappings 15 of the potential divider and the fixed resistance 14, it can be arranged that, when the elevator or conveyor carriage is at the level corresponding to the chosen switch 16, the potentials at the selected tapping 15 and at the sliding contact 12 are equal, and current therefore ceases to flow through the relays S and D, which are therefore de-energised. On the other hand, when the potential at the contact 12 is not equal to that at the pre-selected tapping 15, current flows through one of the relays D or S, according as the potential at the contact 12 is greater or smaller respectively than that at the chosen tapping 15, that is, according as the carriage is on one side or another of the selected level. If the relays D and S are inserted in the operating circuit of a driving motor for the elevator or conveyor so as to cause, upon energisation, movement of the motor in different directions, it can be arranged that the elevator or conveyor carriage moves in the desired direction, up to the moment when it reaches the selected level, at which the potentials at the contact 12 and at the tapping 15 corresponding to the selected level will be equal and the relay which had been energised will be de-energised, stopping the motor and therefore the carriage. This will always happen with safety even if the carriage is initially stopped at an intermediate position between two levels.

Naturally the diagonal arm of the bridge represented schematically in FIG. 1 will in practice require certain modifications for satisfactory control of the relays D and S.

The potentiometer 10 and its sliding contact 12 can be realized in various ways. One of these consists in placing a long conductive potentiometer wire 10 for the whole length of the carriage travel -- that is, the entire length of the elevator shaft in the case illustrated in FIGS. 1a and 2 and connecting the sliding contact 12 mechanically to the carriage, part of which is shown at 12a in FIG. 1a, the wire 10 being anchored at upper and lower points 11 and 13 connected electrically to the positive and negative terminals of the direct current supply. The sliding contact 12 may be of any suitable type, for example a brush with contacts urged by a spring into contact with the wire 10.

In a preferred practical embodiment of the invention sliding contact 12 is fixed at a point in the static installation of the elevator, while the potentiometer wire 10 moves with the elevator carriage. With such an arrangement, the potentiometer wire 10 can be constituted by the steel cable already present in all elevator installations to operate the speed-limiter, as will be described shortly, thus realising an economy in component parts.

FIG. 2 represents a practical form of potentiometer forming part of a movement pre-selection device according to this invention. Upper and lower fixed pulleys 22 and 24 are provided to act as guides for a vertical steel cable 26 which operates the speed-limiter of an elevator (not shown). The upper pulley 22 is mounted on a part of the static structure above the upper end of the elevator shaft, while the lower pulley 24 is mounted on an arm 28 hinged to a bracket 29 which is formed with a collar 30 anchored to a vertical support 32 fixed relative to the static structure. A counterweight 34 at the free end of the arm 28 helps to maintain the cable 26 in tension. A connector piece 36 interconnects the ends of the cable 26, clamping the respective cable ends 38 and 40, and is anchored to a point on a elevator cabin (not illustrated).

The upper pulley 22 is insulated from the fixed structure, or from earth, by insulating layers 42, 44 and 46. Similarly the lower puulley 24 is insulated from the fixed support 32 by an insulating layer 48 interposed between the collar 30 and the support 32. Finally the ends 38, 40 of the cable 26 are insulated from each other by insulating discs 50, 52. A direct voltage is applied between the ends 38 and 40 of the cable 26 so that the latter forms a potentiometer wire: the upper pulley 22 (supposing the elevator operating machines to be at the top of the elevator shaft) forms the equivalent of a sliding contact the position of which along the cable 26 determines the potential at the pulley 22, this potential being representative of the position of the elevator cabin in the shaft. The arrangement shown in FIG. 2 is therefore a practical realisation of the potentiometer 10, 12 illustrated in FIG. 1.

In the case where the elevator operating machinery is located at the bottom of the elevator shaft, the lower pulley 24 would be utilised as the sliding potentiometer contact of the cable 26.

FIG. 3 illustrates in a simplified form a typical elevator installation of the prior art with three stopping levels each provided with a switch. A power supply unit AFCS contains fuses, contacts or safety devices and is supplied with electrical power from a mains supply through a master switch IG which also connects the power supply to a motor unit CTM which includes motor control relays, contacts and the elevator driving motor itself.

The unit AFCS has two power supply terminals one of which, 30, is earthed and the other 32, supplies a negative potential -V to three circuits arranged in parallel and each including a level selector push-button B1, B2, B3, and a respective coil of a level relay R1, R2, R3, through protection contacts Sb and Db, normally closed, arranged in series and controlled respectively by upwards and downwards relays S and D and described later. Two further protection contacts Sa, Da, normally open, are placed in parallel and are controlled by the upwards and downwards relays S and D respectively.

The potential -V is applied through the coils of the level relays R1, R2, R3 through respective maintenance contacts R1a, R2a, R3a controlled by the respective relays, and through respective contacts R1b, R2b, R3b controlled by the same respective level relays R1, R2, R3, to the upwards relay S and the downwards relay D through respective level switches C1, C2, C3 located at the respective stopping levels.

Of the level switches, only C2 is a three-way commutator switch, the two switches C1 and C3 being two-way switches located at the two extreme levels at the ends of the elevator shaft. In lift installations with more than three levels, each of the intermediate levels will be provided with a three-way commutator switch similar to C2.

FIG. 3 illustrates the situation were a slide SC fixed to the elevator cabin is in a position between the levels corresponding to switches C1 and C2. It will be supposed that the cabin is to be brought to the level of switch C2. Pressing the selector button B2 causes the relay R2 to be energised, closing the associated contact R2a and R2b and thereby energising, through the switch C2, the upwards relay S. If the cabin were initially higher than the level of switch C2, the switch C2 would have been in its other position and would have completed the circuit of the downwards relay D.

The excitation of the upwards relay S causes closure of the associated contacts Sa and opening of the contacts Sb, breaking the excitation circuit of the level relay R2 including the push-button R2, while closing a maintaining circuit for the same relay R2 through the contacts Sa and the maintenance contacts R2a. Simultaneously further contacts (not illustrated) associated with the relay S energise the elevator motor in the unit CTM in such a direction as to raise the cabin.

When the cabin has ascended to the level of the switch C2, the moving contact of the switch C2 is shifted by the slide SC into a central position, breaking the energising circuit of the upwards relay S. The de-energisation of the relay S opens the contacts Sa, de-energising the level relay R2. The cabin therefore at the selected level.

FIG. 4 shows an elevator installation having three stopping levels in accordance with this invention. The installation includes the power supply unit AFCS, a master switch IG and a motor unit CTM as in the installation of FIG. 3. Energising circuits for respective level relays R1, R2, R3, are formed through protection contacts Sb, Db and respective level selector push-buttons B1, B2, B3. Further energising circuits are formed through protection contacts Sa and Da and maintenance contacts R1a, R2a, R3a of the respective relays R1, R2, R3. In this case, however, the unit AFCS supplies equal and opposite potentials +V and -V to terminals 40 and 42 connected to a pre-selection device according to the invention similar to that described with reference to FIG. 1.

The device shown in FIG. 4 includes however means for amplifying the signal appearing in the sensing diagonal of the Wheatstone bridge. For easier reference the reference numerals used are the same as those in FIG. 1, except that the diodes 18, 20 of FIG. 1 are replaced by amplification circuits comprising complementary transistors 17 (PNP) and 19 (NPN) having respective base supply resistors 21 and 23. Furthermore the switches 16 of FIG. 1 are now replaced by contacts R1b, R2b, R3b, controlled respectively by the level relays R1, R2, R3. It will be seen that the power supply unit AFCS now provides a further potential -V1, intermediate between earth potential and the excitation voltage V2 of the level relays R1, R2, R3, to maintain the sliding contact 12 of the potentiometer 10, 12 at a fixed potential.

The selection device in FIG. 4 also includes, as an optional feature, maintenance contacts Sc and Dc for the relays S and D respectively, and a magnetic maintenance contact CM, the purpose of which will be described later.

The installation of FIG. 4 operates as follows. It will again be supposed that the elevator cabin is to be brought to the level of relay R2, and that the cabin is initially below this level. The selector button B2 is pressed, energising the relay R2 and consequently closing the contacts R2a and R2b. Since the cabin is below the destination level, the potential of the contact 12 will in this case be lower than the potential at the closed contacts R2b on the subdivided resistance 14, so the PNP transistor 17 will conduct, energising the associated upwards relay S, which will close its protective contacts Sa to maintain the energisation of the level relay R2 through the contact R2a independently of the subsequent position of the button B2, while at the same time opening the contacts Sb. The maintenance contacts Sc will also close, and will thereafter keep the upwards relay S excited, through the normally closed contacts CM, independently of the state of the transistor 17. On the other hand, in the branch of the bridge sensing diagonal including the downwards relay D, the NPN transistor 19 remains blocked.

As the cabin nears the destination level the potential difference between the sliding contact 12 and the closed relay contacts R2b corresponding to the selected level decreases until it is below the conduction threshold of the transistor 17; the transistor 17 will then cease conduction, but the relay S will continue to be energised through the maintenance contacts Sc. When, however, the cabin has reached the destination level a respective double magnetic armature 44, fixed accurately at each level, opens the normally closed magnetic contacts CM, breaking the energisation circuit of the relay S and causing the elevator cabin to stop.

The need for the auxiliary contacts such as the magnetic contacts CM will be avoided if the amplification in the sensing diagonal of the bridge is such as to impart sufficient sensitivity to the bridge to obtain cut-off of the transistor 17 or 19 as the case may be within potential limits on the potentiometer wiper 12 such that the cabin stops at the selected levels within the position tolerance required. In this case the maintenance contacts Sc and Dc could be dispensed with as well as the magnetic contacts CM and the double armature 44.