US3774728A

US3774728A - Elevator call circuit

Info

Publication number: US3774728A
Application number: US00252338A
Authority: US
Inventors: A Metzler; W Wright; J Rowell; R Collette
Original assignee: Guardian Electric Manufacturing Co
Current assignee: Guardian Electric Manufacturing Co
Priority date: 1972-05-10
Filing date: 1972-05-10
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27

Abstract

A control system for elevators or the like wherein the elevator call button generates a first signal which is in turn sensed by the control circuit. The control circuit then provides a second signal of greater duration than the first. The second signal is utilized to produce energization of a relay which in turn controls the operation of the elevator motor and related equipment. A threshold device prevents operation of the relay when the first signal is below a threshold level so as to prevent accidental operation of the elevator by low level spurious signals. All of the control circuitry may be positioned remote from the signal generator in a safe environment. Additionally, short circuiting of the leads from the signal generator will not initiate operation of the elevator.

Description

United States Patent 1191 v y 1111 3,774,728 1451 Nov; 27, 1973 "Metzler et al;

ELEVATOR CALL CIRCUIT Assignee: Guardian Electric Manufacturing flqmy nytchieasa l'lflQlS.

Filed:

Primary ExaminerBemard A. Gilheany Assistant Examiner-W. E. Duncanson, Jr. Att0meyA. W. Molinare et al.

[57] ABSTRACT A control system for elevators or the like wherein the elevator call button generates a first signal which is in turn sensed by the control circuit. The control circuit May 10, 1972 then provides a second signal of greater duration than the first. The second signal is utilized to produce ener- [21] Appl' N 252338 gization of a relay which in turn controls the operation of the elevator motor and related equipment. A [52] US. Cl 187/29 R threshold device prevents operation of the relay when 1 [51] Int. Cl B66b 1/46 the first signal is below a threshold level so as to pre- [58] Field of Search 317/141, 148.5, 154; vent accidental operation of the elevator by low level 307/267; 187/29 spurious signals. All of the control circuitry may be positioned remote from the signal generator in a safe [56] 7 References Cited environment. Additionally, short circuiting of the UN E STATES PATENTS leads from the signal generator will not initiate opera- 3,473,o50 10/1969 Groom 307/267 the elevator- 3,602,771 8/1971 Walstad et al. 317 154 x 19 Claims, 2 Drawing Figures 3,571,626 3/1971 Reif 307/267 X 3,504,236 3/1970 Miyagawa et al.. 317/1485 volved is to be consideredtypical even though the following specification is in the context of this elevator type application.

Generally, an elevator control system utilizes push buttons arranged at each floor. Upon depression of the push button, an electric switching circuit is completed and a controlsignal isfed into a relay matrix. This relay matrix in' turn'operates to sendthe elevator to the appropriate floor. This system'and similar systems which provide for making acircuitupon operation of a button or the like have beenrefine'd and now arejhighly sophisticated toprovide'the users of the elevator with prompt and fast service. I

-However, elevators utilizing this type of control cir- J cuitry have an inherent disadvantage. This disadvan tage becomes apparentduring-emergencies such as fires. In such situations; the high temperature due to I a firemay cause theleads associated withthe push button to short. Consequently, anyone utilizing an elevator as an escape route ,may have-the cab of the elevator called to the floor upon which the fire is raging. This has in fact been the case in numerous circumstances. Thus, it is desirable to provide an elevator call system which will avoid such tragic happenings.

SUMMARYYOFA THE INVENTION In aprincipal aspect, the present invention comprises a control system wherein a signal generator in a circuit is connectedto a threshold device and to an energy storing circuit so-that upon providing a signal which is indicative ofa command, the threshold .device will provide an-outputto a command relay arrangement. This output for'the command relay arrangement will in turn closea circuit associated with operation of the con- 3 trolled device. Because the control system requires the will be made drawing cornprised 5f the following? FIGURES; a v

FIG. 1 is a schematiclayoutof an entire control system as utilized for an elevator. call system; and I FIG. 2 is a circuit diagram of a single call station as contemplated by the present invention.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENT Referring first to FIG. 1 ,there is illnstrated schematically the arrangement of the present invention as would be utilized for an elevatorcall circuit. A plurality of push buttons 10-13 would be arranged in serial order on floors l through-n in a desired building. The push button would be a pulse signal generator device. Atypical exampleof sucha device is disclosedin the now pending application of Britton et al Ser. No. 170,729

filed Aug. 11, 197.1. Such a device includes a coil with twoileads extending therefrom. Depression of the push button drives a core through the coil thereby generat-'- ing a pulse in the coil and through the leads. These leads as at leads 1 4-17 would all be connected through the'control circuitry at some remote station 18. In this manner, the station 18 could be protected against first and other dangers. Additionally, the station 18 could be maintainedat a central location for ease of repair and access for maintenance. Ancillary to the station 18 would be a series of indicator lights at 19. Typically, such indicator lights would show, whether a particular set of leads 14-17 were functioning correctly. Outputs 20-,23 from a station 18 would 'connectwith a relay matrix for controlling elevator motors, brakes and the like.

That is, all of the leads 20-23 would be connected with a control matrix for one or'more elevators.

In FIG. 2, there isillustrated a circuit diagram associated with the control mechanism or system of the invention as provided atone control station, for example, the first-floor in an elevator system. Thus, like parts are correspondingly labeled in FIG. 2. Note that the lead 14 is now identified as

leads

14a and 14b since this is a two wire system. Also, outp ut lead 20 is now identified asleads'20a and 20b.

generation of a first signal orv pulse before the control operation is initiated, the control circuitry cannot-be activated by the open circuiting or short circuiting of the input leads'to the control circuitry. Thus, aihigh temperature fusion of the lead wires to the signal generator will not cause a malfunction of the control system that could possibly lead to disasterous'results. I

It is thus an object of the present invention to provide an improved control system;

It is a further object of the present invention to pro- I vide animproved control system wherein a pulse signal is utilized to initiate operations of the control system.

Still another object of the present invention is to provide a safe and economical, control systemwhich can- I not accidentally be activated to provide an'unwanted control signal.

' These and other objects,-advantages and features of the present invention will be set forth in greater detail in the description which follows.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description which follows, reference The pulsegenerator l0'provides. a firstsignal input via a coil 24 to the circuit comprised of three stages each stage being associated with a

separate transistor

26, 28 and 30. The stage of transistor 26 provides a high impedance input circuit to keep transmission line losses to a minimum. The stage of transistor 28 acts as a pulse stretcher. The stage of transistor 30 acts as the driver for an electromechanical load. Details of operation are as follows:

The pulsegenerator 10 via coil 24 feeds a positive going pulse or first signal through a diode 32' into the relatively high input impedance of transistor 26 which is connected as an emitter follower. Diode 32 blocks any negative going pulse generated by the pulse generator 10. The positive pulse on the base of transistor 26 causes it to conduct charging capacitor 34. Inthe circuit shown, with compound values as set forth below, capacitor 34 is fully charged in approximately I millisecond.

The charging of capacitor 34 causes conduction in transistor 28 which, in turn, causes conduction in transistor 30, thus energizing a relay 36. Capacitor 34 discharges supplying a second signal of greater duration than the'first signal through the high impedance input 'of transistor 28. The slow discharge of capacitor 34 in 34 and resistor 38. The relay 36vis first energized on conduction of transistor 30. After initial energization in this manner, the relay 36 latches itself in through its normally open contacts 40 and the transistor 30 terminates conduction. Normally open contacts 42 of relay 36 performthe switching function to the load via

leads

20a and 20b. Relay 36 remains latched through contacts 40 until released by switch 44 in series with con-- tacts 40. In an elevator control circuit, the load would be the elevator motor or motor controller and the release switch 44 would provide a position feedback signal as switch 44 became operated by the elevator car upon arrival near its floor destination.

Aresistor 46 is providedto present a lower impedance toxthe pulse. generator than the input impedance of transistor 26, thereby reducing the amplitude of various transient noise pulses which would be picked up on the transmission line and presented to the base of transistor 26. Capacitor 48 provides a by-pass for high frequency transients which might otherwise trigger the

device.Resistors

50 and 52 are current limiters for

transistors

26 and 28 respectively, and prevent any spurious surges from damaging the transistors. Resistor 54 provides the low impedance path to charging capacitor 34 and in conjunction with transistor 26 provides the high impedance input to the system.

Resistor 38 is provided to assure that capacitor 34 discharges completely between operations. Resistor 58, in conjunction with transistor 28 provides the high impedance discharge path for capacitor 34 and thus provides the effect of pulse stretching. Resistor 60 and

diodes

62 and 64 provide reverse bias on transistor thus providing a threshold device. Since the voltage at base of transistor 30 must be greater than the bias level at the emitter of transistor 30, there is afforded more protection against accidental activation of the relay by low level spurious signals. Resistor 66 provides a base return for transistor 30.

Diodes 65-68 form a diode bridge full wave rectifier for 30 volt unfiltered direct current for the operation of the relay 36. Half 'of the supply is filtered by a capacitor 70 and is used as the power source for transistors 26 and28. Diode 72 is used to shunt the inductive ef- Element Rating :1. Resistors Value 46 15 K 0 54 l K I). 50 V 270 Q 38 1.0 Meg Q 52 270 0. 58 1.5 K 0 66 10.0 K 0 60 15 K O.

b. Capacitors 48 0.01 microfarads The transistors26, 28 and 30 are NPN type, transistors, Model No. 2N3414.

What'is claimed is: 1. An electrical elevator call control system which I provides command output signals to 'a controlled device comprising, in combination,

means for generating a first signal, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating meansfor generating a second signal having a duration greater than said first signal,

a commandrelay means for providing an output signal to said controlled device,

means connected to said relay and to said stretching means for energizing said relay in response to said second signal and interlock means for said command relaymeans en- I gageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said controlled. device. 7 a v v 2. The system asset forth in claim 1 including threshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals below said predetermined level'will not accidentally energize said relay.

3. The system of claim 1 wherein said signal stretching means includes an energy storage device having an input charging impedance and an' output discharging impedance greater than said input charging impedance,

said energy storage device being connected between said first signal generating means and said relay energizing means. I I

4. The system of claim 1 whereinsaid feedback control means comprise circuit breaker meansin'series with said relay, said circuit breaker means being operative in response to said controlled device.

5. The system of claim l wherein said components are direct current responsive.

6. The system of claim 1 including a plurality of said.

systems, each one of said systems being associated with a separate command station.'

10. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination,

means for generating a first signal including an input, signal stretching means connected to said first signal generating means, said stretching means being. responsive to said first signal generating means for generating a second signal having a duration' greater than said first signal, means connected between said firstand saidsecond signal generating means for shorting out high frethreshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals I below said predetermined level will not accidentally energize said relay.

12. The system of claim wherein said signal stretching means includes an energy storage device having an input charging impedance and an output discharging impedance greater than said input charging impedance, said energy storage device being connected between said first signal generating means and said relay energizing means. I

13. The system as set forth in claim 10 including interlock means for said command relay means engageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said con: trolled device.

14. The system of claim 13 wherein said feedback control means comprise circuit breaker means in series with said relay, said circuit breaker means being opera- 6 tive in response to said controlled device.

15, The system of claim 10 wherein said components are direct current responsive.

16. The system of claim 10 including a plurality of said systems, each one of said systems being associated with a separate command station.

17. The system of claim 10 wherein said means for generating a first signal comprises a coil and means for inducing a voltage in said coil.

18. The system of claim 17 including a separate low amperage test circuit in parallel with said coil.

19. An electrical elevatorcall control system which provides command output signals to a controlled device comprising, in combination,

means for generating a first signal,

a low amperage test circuit in parallel with said means for generating a first signal,

signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration second signal.

output sig-

Claims

1. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for genErating a first signal, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, a command relay means for providing an output signal to said controlled device, means connected to said relay and to said stretching means for energizing said relay in response to said second signal, and interlock means for said command relay means engageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said controlled device.

2. The system as set forth in claim 1 including threshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals below said predetermined level will not accidentally energize said relay.

3. The system of claim 1 wherein said signal stretching means includes an energy storage device having an input charging impedance and an output discharging impedance greater than said input charging impedance, said energy storage device being connected between said first signal generating means and said relay energizing means.

4. The system of claim 1 wherein said feedback control means comprise circuit breaker means in series with said relay, said circuit breaker means being operative in response to said controlled device.

5. The system of claim 1 wherein said components are direct current responsive.

6. The system of claim 1 including a plurality of said systems, each one of said systems being associated with a separate command station.

7. The system of claim 1 wherein said means for generating a first signal comprises a coil and means for inducing a voltage in said coil.

8. The system of claim 7 including a separate low amperage test circuit in parallel with said coil.

9. The system as set forth in claim 1 including means connected between said first and second signal generating means for shorting out high frequency spurious signals from the input to said first signal generator means.

10. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for generating a first signal including an input, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, means connected between said first and said second signal generating means for shorting out high frequency spurious signals from the input to said means for generating a first signal, a command relay means for providing an output signal to said controlled device, and means connected to said relay and to said stretching means for energizing said relay in response to said second signal.

11. The system as set forth in claim 10 including threshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals below said predetermined level will not accidentally energize said relay.

12. The system of claim 10 wherein said signal stretching means includes an energy storage device having an input charging impedance and an output discharging impedance greater than said input charging impedance, said energy storage device being connected between said first signal generating means and said relay energizing means.

13. The system as set forth in claim 10 including interlock means for said command relay means engageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said controlled device.

14. The system of claim 13 wherein said feedback control means comprise circuit breaker means in seriEs with said relay, said circuit breaker means being operative in response to said controlled device.

15. The system of claim 10 wherein said components are direct current responsive.

19. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for generating a first signal, a low amperage test circuit in parallel with said means for generating a first signal, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, a command relay means for providing an output signal to said controlled device, and means connected to said relay and to said stretching means for energizing said relay in response to said second signal.