US3807480A

US3807480A - Door with automatic fire restricting system

Info

Publication number: US3807480A
Application number: US00256130A
Authority: US
Inventors: J Smart
Original assignee: Won-Door Corp
Current assignee: Won-Door Corp
Priority date: 1972-05-23
Filing date: 1972-05-23
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: NL7307201A; FR2186060A5; BR7303773D0; IL42299A; CA992651A; JPS5440198B2; ZA733300B; CH580745A5; DE2325939C3; IL42299A0; NL162561C; GB1418190A; SE394128B; BE799941A; DE2325939A1; DE2325939B2; JPS4949441A; AR201194A1

Abstract

In response to detection of fire, electronic means controls overload sensitive closing of a door to a protected space. The door remains closed for a short warning period and is then partially opened automatically for a predetermined period to permit escape of persons from the protected space. Upon final closing of the door, fire extinguishing means are operated within the protected space.

Description

United States Patent [1 1 Smart [451 Apr. 30, 1974 4] DOOR WITH AUTOMATIC FIRE 2,841,389 7/1958 Litherland 49/27 RESTRICTING SYSTEM 3,599,371 8/1971 Barroero 49/30 3,509,934 5/1970 Smart 160/84 R [75'] Inventor: Jay A. Smart, Salt Lake City, Utah. 3,720,254 3/ 1973 Smart 160/84 R [73] Assignee: Won-Door Corporation, Salt Lake City, Utah Primary Examiner-Peter M. Caun Attorney, Agent, or Firm-Clarence A. OBrien; Har- [22] Flled. May 23, 1972 vey B Jacobson [21] Appl. No.: 256,130 1 I [57] ABSTRACT [52] US. Cl. 160/1 In response to detection 6f fire, electronic means com [51] Int. Cl E05f 15/20 trols overload sensltlve closlng of a door to a pro- [58] Fleld of Search 160/1, 5, 6, 84 R, d 1 Th d l d f h 49/27 30 tecte spao e. e 00! remains cose or a s ort Y warmng penod and 1s then partially opened automati- [56] References Cited cally for a predetermined perrod to permlt escape of persons from the protected space. Upon final closlng UNlTED STATES PATENTS i of the door, fire extinguishing means are operated 3,337,992 8/1967 Tolson 49/29 within the protected space, 2,678,212 5/1954 Flostroy... 2,871,009 H1959 Picatti 49/30 f 13 Claims, Drawing Figures f :2 \vs 0-34 a4- I o o o a; l I I 30 3a E 2a I Door way Pulley Drive I: Sys!em 38 r E/EC/IO' l mag/relic N c/u/m 42 [I r 555%" I DC Molar 44 {-24 2" Electron/c i i Carma/s J l "f S S I Lead Pas! PMEWEBAPRW aw zmalmso Fig Lead Pas? This invention relates to automatic closure operating systems and more particularly to a door closing and opening system that is programmed for fire emergency purposes.

. An important object of the present invention is to provide an automatic control system for a power operated, fireproof door whereby opening and closing of the door to a space protected by a fire sensing and fire extinguishing system, may be closed off in order to isolate and extinguish the fire and yet enable any persons trapped in such space to escape without injury. Such a door operating system requires different door closing and opening modes as well as timing in order to meet fire emergency conditions. The system of the present invention therefore combines the qualities of a fireproof door with automatic door operation and actuation of fire extinguishers whereby fire may be isolated or contained, extinguished and yet allow rapid and panic-free evacuation.

by a header 22 and a female jamb 24. The passageway 12 is adapted to be closed by a fireproof closure device or door generally referred to by reference numeral 26 of a typedisclosed for example in my prior US. Pat. No. 3,509,934. The door 26 is adapted to be closed or opened'by power operating mechanism generally referred to by reference numeral 28 through a cable systern that extends from the power operating mechanism which is positioned, for example, adjacent to the wall 16. The cable extends through the upper frame member 30 on top of the access passageway 12 and into the jamb 24 adapted to be engaged by the lead post 32 of the door in its fully closed position.

- The installation shown in FIG. 1 is adapted to be associated with a protected enclosure or space within which fire sensing devices are mounted such as ionization type smoke detectors. These fire detecting systems i are well known, the details of which form no part of the In accordance with the present invention, any conpersons attempting to escape during this operational phase. When the door is fully closed, a timer controlled mode of operation ensues during which the door is partially opened and then closed for a predetermined period of time. The timer-controlled partial opening and closing operation is repeated at least two times in order to permit persons to evacuate the space through the access opening within which the door is installed. Upon final closing of the door, fire extinguishers are triggered into operation within the protected space. Automatic control may be overridden at any time by a manual operational mode wherein the door is selectively opened at any time. The electronic controls through which automatic or semi-automatic operation is effected, operate on the doors through a power operated drive mechanism featuring an electromagnetic clutch that is deenergized whenever the door is at rest in order to prevent damage to the drive mechanism and permit manual override.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

FIG. 1 is a front elevational view of an access region associated with a protected space wherein the closure andthe automatic operating system of the present invention is installed.

FIG. 2 is a functional block diagram illustrating the control system of the present invention. 1

FIG. 3 is an electrical circuit diagram corresponding to the control system of FIG. 2.

Referring now to the drawings in detail, FIG. ll illustrates a typical installation for the present invention generally referred to by reference numeral 10. As shown in FIG. 1, an access passageway 12 to and from a protected enclosure or space within a building is defined between

vertical walls

14 and 16, a ceiling l8 and floor 20. The access passageway is furthermore framed present invention. Further, such fire detecting systems are often associated with fire extinguishing facilities. In the installation shown in FIG. 1, by way of example, nozzles 34 may be mounted on the header 22 from which fire extinguishing medium may be discharged in spray form into the protected space for extinguishing any fire after it is confined to said space by closing of the door 26 to seal the space.

Before the protected space is sealed, and the fire extinguishing means triggered into operation, the door 26 is operated in such a fashion as to provide a warning and permit evacuation of the protected space. Thus, closing and opening operation of the door is effected by means of the power operating mechanism 28 in an automatic fashion with manual override. As hereinbefore indicated, movement of the door is closing and opening directions is imparted by the power operating mechanism through the cable system which includes cables 36 associated with a pulley drive arrangement generally referred to by reference numeral 38 that is drivingly connected to the output of a reduction gear assembly 40 through an electromagnetically operated clutch device 42. A reversible DC motor 44 drives the reduction gear assembly 40. An electronic control assembly generally referred to by reference numeral 46 controls operation of the motor 44 and the electromagnetic clutch 42. r

FIG. 2 diagrammatically. illustrates the electronic control assembly which is operative to energize the motor 44, the motor being in turn drivingly connected through the clutch device 42 to the pulley drive system 38. The control assembly is connected to a DC source of electrical energy by means of positive and

negative voltage lines

48 and 50. A power regulator 52 is connected across the 'voltage lines for supplying a reduced DC voltage to some of the components in the control assembly. The motor 44 is connected to the power supply through the

voltage lines

48 and 50 in series with a high current switch component 54 and a high current sensor component 56 through a reversing switch assembly 58 by means of which the direction of rotation of the motor is selected in order to effect either closing or opening movement of the door. Actuation of the reversing switch assembly 58 and selection of the motor direction, is effected through a drive control component 60 to which drive producing signals are fed from a pair of

control logics

62 and 64 respectively operative to effect closing an opening operation. The close logic 62 and open logic 64 are respectively triggered into operation by signals supplied thereto from a gate circuit 66. Alternatively, the close and

open logics

62 and 64 may be triggered into operation manually by actuation of

switches

68 and 70 respectively connecting the logics to the negative voltage line 50.

The high current switch component 54 is normally rendered operative whenever the reversing switch assembly 58 is supplying energy to the motor to remain conductive regardless of the load condition on the motor and thus maintain the motor energized. A load control component 72 is connected to the high current switch assembly 54 in order to render the high current switch assembly sensitive to overload conditions on the motor resulting in the opening of the switch assembly 54 and de-energization of the motor momentarily during a logic controlled phase of operation. This phase of operation is initiated by a signal from a fire detector 74 of the type aforementioned. The fire detector is connected through a latching switch component 76 to an automatic repetitive close logic 78 that generates operating pulses transmitted by the gate circuit 66 to the close logic 62 during the logic controlled phase of operation. Whenever a signal is initially fed to the close logic 62 to initiate closing of the door, a signal is also fed to disable logic 80 through which a disable signal is fed to the load control component 72 in order to render the high current switch assembly 54 temporarily insensitive to motor overload during the logic controlled phase of operation for starting purposes.

During the logic controlled phase of operation, the door begins to close but whenever it meets an obstruction, its movement is momentarily arrested. After a short delay, closing is again attempted. When the door is fully closed, the logic controlled phase of operation is terminated by a limit switch 82 actuated by the lead post of the door engaging the jamb 24, for example. Actuation of the limit switch 82 triggers into operation the timer component 84. Also, during the logic controlled phase of operation, each time the movement of the door is arrested, the motor is de-energized whereupon the clutch 42 is also de-energized so as to isolate the door drive from the motor while at rest.

During the foregoing logic-controlled phase of opera tion, a warning period is established by the closing of the door without any possible injury to persons attempting to enter or exit the passageway. When the warning period is completed upon sealing of the protected space by closing of the door fully, a timercontrolled operational phase is initiated beginning with a three second delay before partial opening of the door is effected in response to a signal fed to the open logic 64 from the timer through the gate circuit 66. During the timer-controlled phase of operation, sensor component 56 is operative through the load controlled component 72 to render the high current switch assembly 54 insensitive to overload of the motor so that the motor will remain energized until the door is partially opened to a predetermined extent at which time the motor is de-energized and the door remains partially opened for a preset period of time determined by the timer 84. The door then closes in response to a signal supplied to the close logic by the timer through the gate circuit 66. The door remains fully closed for an interval of about five seconds after which it opens partially again for a shorter preset period determined by the timer 84. Finally, the door is fully closed under control of the timer and the first extinguisher component 86 triggered into operation.

FIG. 3 illustrates in greater detail the control system. The high current switch assembly 54 as shown includes a triac 88 having its anode connected to the positive voltage line 48 and its cathode connected by line 90 to the motor control circuit 58. Thus, the triac 88 is connected in series with the motor load 44 when the motor control circuit is completed. Also connected in series with the motor load is the resistor 92 of the high current sensor 56 interconnected between the motor and the negative voltage line 50. Under normal load conditions, the voltage drop across the anode and cathode of the triac 88 exceeds break-over voltage value so that the triac conducts and enables operation of the motor. Under overload conditions, however, the voltage across the anode and cathode of the triac is below break-over value which would cause the triac to switch off unless a positive voltage is applied to its gate from the positive voltage line 48 through the gate control resistor 94 upon closing of a normally open relay switch 96. The voltage applied to the gate of the triac is regulated by the resistors 98 and 100 interconnected by the diode 102 between the gate and the negative voltage line 50. The relay switch 96 is closed in response to energization of a relay coil 104 that may be energized whenever the motor control circuit is activated. Thus, the motor will not start if there is any initial overload but may remain energized should any overload occur thereafter.

The motor control circuit includes a door closing relay coil 106 energized in response to a drive signal output from the drive control component 60 connected to the relay coil 106 through diode 108. Upon energization of the relay coil 106, the relay switch 110 is actuated in order to connect the voltage line 90 to one terminal of the motor 44 through line 112 while the other motor line 114 is connected, by closing of the normally opened relay switch 116, to the negative voltage line 50 through the resistor 92. Normally opened relay switch 118 is also closed in response to energization of the relay coil 106 in order to complete an energizing circuit through the gate controlling relay coil 104 in series with resistor 120 and diode 122. Thus, relay coil 104 may be energized simultaneously with relay coil 106 in order to initiate operation of the motor in a closing direction. Similarly, operation of the motor may be initiated in an opening direction by energization of the relay coil 124 in the motor control circuit to close the normally opened relay switch 126 thereby also completing an energizing circuit for the relay coil 104 in the high current switch assembly in series with the resistor 120 and diode 128. The door opening output of the drive control component 60 is therefore connected to the diode 128-and through diode 130 to the relay coil 124 for energization thereof. When energized, the relay coil 124 also actuates the relay switch 132 and the normally opened relay switch 134 in order to establish a reverse connection between the voltage lines and the motor terminal lines 112 and 114 for opening operation of the motor.

The drive control component 60 is connected to the relay coils 106 and 124 through a pair of output lines 136 and 138 respectively connected to the output collectors of

transistors

140 and 142 having their emitters connected to the positive voltage line 48. The bases of

transistors

140 and 142 are respectively connected by '

base resistors

144 and 146 to the output collectors of

signal transistors

148 and 150. The collectors of the transistors 148- and 150 are connected to the positive voltage line 48 through

load resistors

152 and 154. The

signal transistors

148 and 150 which are normally nonconductive, are switched on by signals respectively applied to the bases thereof from the close logic 62 and

ciated relay coil

106 or 124 in the motorcontrol circuit.

The energizing circuit established-for the relay coil 104 in the highcurrent switch assembly 54, by closing ofeither, of thenormally'open relay switches 118 and 1 26, may be shunted by switching on of a semiconductor controlled rectifier (SCR) 1-56 in the load control component 72. The SCR 156 has its anode connected to the juncture between resistor 158 and the diode 1 59 interconnected between the resistor 120and the positive voltage line 48. Thus, the voltage across the anode and cathode of the SCR 156 is held below break-over value. The SCR 156 may, however, be

switched on by trigger voltage supplied to its gate from the high current sensor 56 which includes an adjustable potentiometer 162 and resistor 160 connected in series sistor 92. Conductor 164 interconnects the juncture between the potentiometer 162 and the resistor 160 with the gate of the SCR 156 in order to apply a reduced positivevoltage to the gate that will switch on the SCR under normal load conditions of. the motor. When switched on, the SCR 156 will prevent energization of the relay coil 104 so that the triac 88 will respond to any overload of the motor and switch off. However, below excessive overload conditions, the voltage supplied by the sensor 56 to the gate of SCR 156 will be below' trigger value. Accordingly, the SCR 156 will switch off and relay coil 104 will be energized to prevent thetriac 88 from switching off because of the positive voltage applied to its gate through the relay switch 96. Thus, the sensor 56 operates through the SCR 156 on the load control component 72 to establish operational limits for the triac 88 causing it to open only in response to excessive overload but not in response to overload occasioned by relatively small obstructions.

During the logic controlled operational phase, the SCR 156 is initially disabled in order to permit energization of the relay coil 104 and momentarily render the triac 88 insensitive to overload conditions-so as to ensure starting of the motor. Toward this end, a reverse bias is applied to the anode of the SCR 156 by closing of the'normally open relay switch 162 connecting the anode of the SCR 156' to the negative voltage line 50. Relay switch 163 is closed by energization of relay coil 165 in response to a pulse supplied thereto from the collector of signal transistor 166 having its base com nected to the output of disable logic 80. The SCR 156 is switched off during the timer controlled operational phase by connecting the gate to the negative voltage line 50- upon closing of the normally open relay switch 168 upon energization of the relay coil 170 connected to the timer component 84. At the end of an operational cycle, the SCR 156 is again switched on by a pos- 6 itive trigger voltage supplied to its gate through diode 172 from the timer component 84.

Each of the

control logics

62, 64 and 80 are similar in operation and arrangement. Each is operative when supplied with a trigger signal to deliver a pulse of predetermined duration to its signal output. Thus, the close logic supplies a pulse of sufficient duration to the base of transistor 148 in the drive control component through the line 174 in order to initiate closing movement of the door while the output line 176 from the open logic 64 supplies a pulse of sufficient duration to the base of transistor 150 in order to initiate opening operation. A pulse of shorer duration is supplied by the disable logic 80 to the 'base of transistor 166 through the line178 to momentarily render the triac 88 insensitive to motor overload as aforementioned. The disable logic 80 is triggered into operation each time an activating signal is applied to the input of the close logic 62 through activating signal line 180. Similarly, the disable logic is activated by an activating signal simultaneously applied thereto when the open logic 64 is activated by a signal in line 182. The duration of the output pulse of each of the control logics is determined by a capacitor 184 associated with each control logic having one side thereof connected to the negative voltage line 50.

As shown in FIG. 3, each of the control logics ineludes four

NAND gates

186, 188, 190 and 192, the

relation to each other and in parallel relation to the refirst gate 186 having three inputs, one of which is connected to the activating

signal line

180 or 182 and another of which is connected to the manual activating

switch

68 or 70 insofaras the

control logics

62 and 64 are concerned. In the case of disable logic 80, both of the aforementioned inputs of the first gate 186 are connected to the

activatingsignal lines

180 and 182. Either of the aforementioned inputs may trigger operation of the control logic. The intermediate input of the first gate 186 is connected to the output of the third gate 190 which is also interconnected with the input of the last gate 192. The output of gate 186' is interconnected with one of the inputs of each of the

gates

188 and 190, the other input of gate 188 being connected to the positive side of capacitor 184 at thejuncture between the capacitor and diode 194 interconnecting the capacitor with the output of gate 186. As a result of this arrangement, a positive cut-off voltage is maintained at the output of the last gate 192 in its inactive state so that an input signal produces a negative output pulse of predetermined duration as aforementioned.

Activating signals for the control logics through

signal lines

180 and 182 are respectively supplied from the outputs of close gate 196 and open gate 198 in the gate circuit 66. One of the inputs in each of the gates is connected by

lines

200 and 202 to the timer component 84 in order to control closing and opening operation during the timer controlled operational phase as aforementioned. The other inputs of the gates. 196 and 198 are interconnected with the output line 204 from the automatic repetitive close signal logic 78 which in its inactive state maintains a positive voltage on the interconnected inputs of the

gates

196 and 198.

The output line 204 is connected to the output of flip-flop 206 in the close signal logic 78 and is also interconnected with the input of the other flip-flop 210. The output of flip-flop 210 is connected through the inverted OR gate 212 to the input of flip-flop 206. The flip-flops'206 and 210 are simultaneously toggled by a signal supplied thereto from the latching switch component 76 through line 214. Each of the flip-

flops

206 and 210 furthermore includes a pair of terminals interconnected by capacitors 216 and connected by resistors 218 to the low DC voltage supply from the regulator 52. Accordingly, when triggered into operation by an output signal in line 214, the close signal logic 78 produces an output pulse of predetermined duration and frequency for effecting closing operation during the logic controlled phase of operation. Operation of the close signal logic 78 is however inhibited during the timer controlled phase of operation by an inhibit gate 220 interconnecting the line 214 with the juncture between the resistor 100 and the diode 102. An inhibit signal is supplied to line 214 when trigger voltage is supplied through the relay switch 96 to the gate of triac 88 for rendering the triac insensitive to overload during timer controlled operation as aforementioned.

The flip-

flops

206 and 210 are rendered operative by the output in line 214 from the latching switch component 76 which includes the

gates

222, 224 and 226. The output of gate 226 is connected to the output line 214 while its input is interconnected between the output of gate 222 and one of the inputs of gate 224. The other input of gate 224 is connected to the fire detector component 74 by means of which the latching switch assembly is switched on. The switch assembly is switched off by a reset pulse connected to one of the inputs of gate 222 to which the negative line 50 is connected by the capacitor 228, the other input of gate 222 being connected to the output of gate 224.

It willbe apparent from the foregoing description, that the control system is operative in a logic controlled mode during a warning period to automatically effect door closing operation with momentary arrest of the movement of the door in response to obstructions. The warning period is followed by a timer controlled evacuation period during which repeated opening and closing of the door-occurs without sensitivity to obstructions. Final closing of the door initiates operation of fire extinguishers. Manualoverride of the system is provided by means of the

switches

68 and 70 providing an activating signal to the close and

open logics

62 and 64 in order to effect either closing or opening of the door whenever desired.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In combination with a closure device and power operating means for closing and opening the closure device, signal triggered logic means connected to the power operating mechanism for only closing the closure device during a warning period, and timercontrolled means connected to the power operating means for repeatedly opening and closing the closure device during an evacuation period following the warning period, said closure device being installed in an access passageway to an enclosed space, fire detecting means mounted within said space for triggering the logic means, and fire extinguishing means mounted within said space for operation in response to sealing of the space by the closure device upon termination of the evacuation period.

2. The combination of claim 1 including a source of electrical energy for energizing the power operating mechanism, load sensing switch means connecting the source to the power operating mechanism for energization thereof below overload conditions, and load control means connected to the switch means for preventing disconnection of source from the power operating mechanism in response to overload conditions during the evacuation period.

3. The combination of claim 2 wherein the logic means includes a pair of control logic devices connected to the power operating mechanism for respectively efiecting closing and opening of the closure device, pulse generating means connected to one of the control logic devices for periodically triggering closing operation of the closure device during said warning period and disable means connected to the control logic devices and the load'control means for initially rendering the switch means insensitive to overload conditions upon triggering of said operation of the closure device.

4. The combination of claim 3 wherein the power operating mechanism includes a motor connected in series with the switch means to the source, and electrically operated clutch means disengaging the motor in response to opening of the switch means.

5. The combination of claim 4 wherein said switch means includes a triac having a gate and relay means for supplying trigger voltage to the gate in response to energization of the power operating mechanism to prevent the triac from switching off under the overload conditions.

6. The combination of claim 5 wherein said load control means includes adjustable means for disabling the relay means during said evacuation period.

7. The combination of claim 6 wherein said timercontrolled means includes gate means for simultaneously disconnecting the pulse generating means from said one of the control logic devices and supplying a triggering signal to the other of the control logic devices.

8. In combination with a closure device and power operating means for closing and opening the closure device, signal triggered logic means connected to the power operating mechanism for only closing the closure device during a warning period, timer-controlled means connected to the power operating means for repeatedly opening and closing the closure device during an evacuation period following the warning period, a source of electrical energy for energizing the power operating mechanism, load sensing switch means connecting the source to the power operating means for energization thereof below overload conditions, and load control means connected to the, switch means for preventing disconnection of the source from the power operating mechanism in response to overload conditions during the evacuation period.

9. The combination of claim 8 wherein said switch means includes a triac having a gate and relay means for supplying trigger voltage to the gate in response to energization of the power operating mechanism to prevent the triac from switching off under the overload conditions.

- control logic devices for periodically triggering closing operation of the closure device during said warning period and disable means connected to the control logic devices and the load control means for initially rendering the switch means insensitive to overload conditions upon triggering of said operation of the closure device.

12. The combination of claim 11 wherein said timercontrolled means includes gate means for simultaneously disconnecting the pulse generating means from said one of the control logic devices and supplying a triggering signal to the other of the control logic devices.

13. In combination with a closure device and a power operating mechanism for closing and opening the closure device. a sensor, logic means connected to the sensor and the power operating mechanism for closing the closure device during a warning period in response to detection of a predetermined condition by said sensor, and timer-controlled means connected to the logic means and rendered operative upon closing of the closure device for repeatedly opening and closing the closure device during an evacuation period following the warning period, said logic means including a control logic device for effecting closing operation of the closure device, drive control means connecting the control logic device to the power operating mechanism for periodically initiating said closing operation during the warning period, overload sensing means for momentarily disabling the power operating mechanism in response to excessive loading of the closure device during said closing operation, and means for disabling the overload sensing means during the evacuation period.

Claims

1. In combination with a closure device and power operating means for closing and opening the closure device, signal triggered logic means connected to the power operating mechanism for only closing the closure device during a warning period, and timer-controlled means connected to the power operating means for repeatedly opening and closing the closure device during an evacuation period following the warning period, said closure device being installed in an access passageway to an enclosed space, fire detecting means mounted within said space for triggering the logic means, and fire extinguishing means mounted within said space for operation in response to sealing of the space by the closure device upon termination of the evacuation period.

3. The combination of claim 2 wherein the logic means includes a pair of control logic devices connected to the power operating mechanism for respectively effecting closing and opening of the closure device, pulse generating means connected to one of the control logic devices for periodically triggering closing operation of the closure device during said warning period and disable means connected to the control logic devices and the load control means for initially rendering the switch means insensitive to overload conditions upon triggering of said operation of the closure device.

7. The combination of claim 6 wherein said timer-controlled means includes gate means for simultaneously disconnecting the pulse generating means from said one of the control logic devices and supplying a triggering signal to the other of the control logic devices.

8. In combination with a closure device and power operating means for closing and opening the closure device, signal triggered logic means connected to the power operating mechanism for only closing the closure device during a warning period, timer-controlled means connected to the power operating means for repeatedly opening and closing the closure device during an evacuation period following the warning period, a source of electrical energy for enerGizing the power operating mechanism, load sensing switch means connecting the source to the power operating means for energization thereof below overload conditions, and load control means connected to the switch means for preventing disconnection of the source from the power operating mechanism in response to overload conditions during the evacuation period.

10. The combination of claim 9 wherein said load control means includes adjustable means for disabling the relay means during said evacuation period.

11. The combination of claim 8 wherein the logic means includes a pair of control logic devices connected to the power operating mechanism for respectively effecting closing and opening of the closure device, pulse generating means connected to one of the control logic devices for periodically triggering closing operation of the closure device during said warning period and disable means connected to the control logic devices and the load control means for initially rendering the switch means insensitive to overload conditions upon triggering of said operation of the closure device.

12. The combination of claim 11 wherein said timer-controlled means includes gate means for simultaneously disconnecting the pulse generating means from said one of the control logic devices and supplying a triggering signal to the other of the control logic devices.

13. In combination with a closure device and a power operating mechanism for closing and opening the closure device, a sensor, logic means connected to the sensor and the power operating mechanism for closing the closure device during a warning period in response to detection of a predetermined condition by said sensor, and timer-controlled means connected to the logic means and rendered operative upon closing of the closure device for repeatedly opening and closing the closure device during an evacuation period following the warning period, said logic means including a control logic device for effecting closing operation of the closure device, drive control means connecting the control logic device to the power operating mechanism for periodically initiating said closing operation during the warning period, overload sensing means for momentarily disabling the power operating mechanism in response to excessive loading of the closure device during said closing operation, and means for disabling the overload sensing means during the evacuation period.