MXPA97008300A - A fire curtain door that includes a sustained opening / pue release system - Google Patents

Abstract

A fire curtain door includes a door opening / sustained opening system that includes an electromagnet that is energized by a controller when the door is in the open position. The energized magnet magnetically attracts a bottom bar of the curtain door to secure the door in the open position. A key control station connected to the controller allows the electromagnet to be energized when the door is in the open position and which allows the controller to de-energize the electromagnet so that the passage of the door causes the door to close. The key control station also includes a test switch that allows the controller to de-energize the electromagnet after a delay interval. The controller also de-energizes the electromagnet after a delay interval in response to the activation of a response to a thermal switch that feels a temperature in excess of a set temperature.

Description

A FIRE CURTAIN DOOR INCLUDING A SUSTAINED OPENING / DOOR RELEASE SYSTEM BACKGROUND OF THE INVENTION 1. Canipo of the Invention This invention relates to curtain doors and more particularly to fire curtain doors having controls for holding said doors. open doors and to automatically start closing those doors. 2. Description of the Prior Art Curtain doors, and more particularly, steel curtain doors, are used to provide security and protection in commercial, institutional and industrial buildings. A typical curtain door includes a curtain placed between a pair of vertical guides on opposite sides of the opening. The curtain is movable up on the guides to allow passage through the opening and is movable down to seal the opening and prevent passage through it.

A typical curtain includes a plurality of rotatably horizontally disposed flanges interconnected together along their sides and having their opposite ends received within the guides positioned on opposite sides of the opening. The lower part of the curtain typically has a lower bar that can include a handle to allow the curtain to be opened manually. The upper part of the curtain is preferably connected to an arrow that is placed on the guides. The arrow is rotatable about its longitudinal axis in relation to a rigid support. A spring placed between the arrow and the rigid support applies to the arrow a moment that balances at least a part of the weight of the door.

A curtain door can be moved to the open position by applying a lifting force to the handle of the lower bar. When open, the curtain door is wound around the arrow until the weight of the door between the guides is insufficient to overcome the spring tension applied to the arrow. In another example, a rotation moment is applied to a gear at one end of the arrow to cause the arrow to rotate thereby winding the door around it. This rotational moment can be applied by an electric motor or by manually pulling a chain connected around the gear, as is known in the art.

When used as a fire door, these curtain doors can be returned to their closed position under certain alarm conditions. For this purpose, the curtain doors of the prior art include a release hinge that secures the spring moment against the arrow. In response to an appropriate alarm, such as a fire alarm, the release hinge disengages from the spring and releases all or part of the spring moment on the arrow. In the absence of moment on the arrow, the weight of the door causes the door to close.

A problem with the release hinge, however, is that once released, the spring must be manually tensioned against the arrow again and the release hinge must be re-engaged. This new manual tension of the spring and the re-coupling of the delayed and potentially dangerous release hinge. Moreover, the time to apply the new tension to the spring around the arrow and to re-couple the release hinge is a disincentive to test the operation of the release hinge on the spring.

It is therefore an object of the present invention to provide a sustained opening / release system for a curtain door that overcomes these disadvantages of the prior art. It is an object of the present invention to provide a curtain door having the sustained opening / release system that allows the curtain door to be lowered to a closed position without releasing tension on a spring. It is an object of the present invention to provide a delayed closing of a curtain door in response to the detection of an over temperature, alarm or lack of power condition. It is an object of the present invention to provide a door opening / sustained opening system that retains a door that is vertically open, such as a curtain door, open and that allows the door to be closed or the door to be closed in a delayed manner in response to the detection of temperature in excess of a desired temperature, the activation of an external alarm or the activation of a test switch.

SUMMARY OF THE INVENTION According to the foregoing, we have invented a curtain door that includes a pair of guides placed in a separate relationship and a curtain that has a plurality of tabs and a lower bar. Each guide has a receiving groove therein and each flange has at least one side thereof rotatably secured with one side of an adjacent flange. The opposite ends of each flange are receivable in the receiving slots of the pair of guides. The lower bar has a side connected to one side of a last flange of the curtain and has opposite ends thereof received in the receiving slots of the pair of guides.

An arrow is positioned perpendicular to the longitudinal axes of the pair of guides adjacent one end thereof. The arrow is connected to one side of one of the plurality of tabs of the curtain opposite the lower bar. The arrow is rotatable about a longitudinal axis thereof so that the curtain can be wound around the arrow. A counterbalance connects to the arrow and applies to it a force that partially opposes the weight of the curtain that resists the winding of the curtain around the arrow. A hinge is fixedly positioned adjacent to the arrow to engage the lower bar or the end of the curtain adjacent to the lower bar when the curtain is wound around the arrow. The hinge coactuates with the lower bar or the end of the curtain adjacent to the lower bar to secure the curtain wrapped around the arrow. A controller connected to the hinge selectively causes the hinge to release the lower bar or the end of the curtain adjacent the lower bar so that the weight of the curtain causes the curtain to unwind from the arrow.

Preferably, the hinge includes an electromagnet energized by a controller to produce a magnetic attraction between the electromagnet and one of the lower bar and the end of the curtain adjacent to the lower bar. A reset switch connected to the controller is activatable to cause power to be supplied to the electromagnet. A closing switch connected to the controller can be activated to terminate the supply of current to the electromagnet. A test switch, a thermal switch and / or an alarm switch is connected to a relay circuit that is connected to the electromagnet. The relay circuit responds to the activation of the test switch, the thermal switch and / or the circuit breaker. alarm to terminate the current supply to the electromagnet a delay interval after the activation of the same.

We have also invented a door restraint system to hold a door that opens vertically open. The restraint system includes an operable electrical hinge placed to secure the door that opens vertically open. A controller is connected to the hinge to control the action of the hinge to secure the door open. A reset switch is connected to the controller to cause power to be supplied to the hinge in response to activation of the hinge. In response to controller current, the hinge operates to secure the door open. The controller includes a relay circuit that removes the current from the hinge after a delay interval. Removing the current from the hinge causes the hinge to release the door.

We have also invented a method to control a door that can be opened vertically. The method includes the steps of (a) raising the door that opens vertically to an open position; (b) energizing an electrically operable hinge to secure the door in the open position; (c) detecting (i) a temperature in excess of a desired temperature, (ii) activating an external alarm and / or (iii) activating the switch; and (d) deenergizing the hinge in response to the detection of (c) (i), (c) (ii) or (c) (iii), wherein the de-energization of the hinge allows the weight of the door to drive the door to a closed position.

BRIEF DESCRIPTION OF THE DUCTS Figure 1 shows a perspective view of a curtain door according to the present invention that includes a controller connected to a key control station and a hinge; Figure 2 is a sectional view taken along lines II-II in Figure 1; Figure 3 is an electrical diagram of the controller, the control station of l ves and the hinge of Figure 1.

DESCRIPTION OF THE PREDILECT EXAMPLE As illustrated in Figure 1, a curtain door 2 is positioned to obstruct an opening 4 in a wall 6. The curtain door 2 includes a pair of guides 8 placed in separate relation on opposite sides of the opening 4. The guides 8 include vertically oriented receiving grooves 10 which are placed in opposition. A curtain 12 is placed through the opening 4. The curtain 12 includes a plurality of horizontally oriented tabs 14 having ends 16 thereof received in the receiving grooves 10 on the guides 8. Each flange 14 has at least one side of they are rotatably interconnected with the side of an adjacent flange 14. A lower horizontally disposed bar 18 is connected to a lower end of the curtain 12, and more specifically to a last flange of the curtain 12 and has opposite ends thereof. received in the receiving grooves 10 of the guides 8.

A rotary arrow 20 is positioned adjacent one end of the curtain 12 opposite the lower bar 18. More particularly, the arrow 20 is positioned perpendicular to the longitudinal axes of the guides 8 adjacent to the front of the opening 4. The arrow 20 has end 24 rotatably coupled to rigid supports 26 which are connected to the wall 6.

A counterbalance 28 applies to the arrow 20 a moment that partially opposes the weight of the curtain 12 which resists the winding of the curtain 12 around the arrow 20. Preferably, the counterbalance 28 is a coiled spring wound around its axis and connected between the arrow 20 and one or more of the rigid supports 26. The counterbalance 28, however, may include a counterweight (not shown) connected to the lower bar 18 by a cable and pulley (not shown). Two or more counterbalances 28 can be used as necessary to counterbalance the weight of curtain 12 to a desired point.

Preferably, a cover 30 is placed over the arrow 20 and between the rigid supports 26. In the exemplary illustrated in Figure 1, a continuous cord or chain 32 is arranged around a pulley (not shown) connected to the arrow 20 for rotation with it. As illustrated in Figure 2, the application of sufficient tension 34 to an appropriate side of the rope or chain 32 causes the arrow 20 to rotate about its axis in a direction 36 which causes the flanges 14 of the curtain 12 they wrap around the arrow 20.

A hinge 38 is rotatably positioned adjacent the arrow 20 to engage the lower bar 18 or the end of the curtain 12 adjacent the lower bar 18 when the curtain 12 is wound around the arrow 20. The hinge 38 coact with the lower bar 18 for keeping the curtain 12 wound around the arrow 20. Preferably, the hinge 38 includes an electromagnet 40 which is magnetically coupled to the lower bar 18 or a flange 14 of the curtain 12 adjacent to the lower bar 18 in response to energizing the electromagnet 40 by a controller 42.

A key control station 44 is connected to the controller 42 and controls the energization of the electromagnet 40. The key control station 44 includes a test switch operable with keys 46, a reset key-lock switch 48, a lamp green indicator 50 and a red indicator lamp 52. Connected to controller 42 there is a thermal switch 54 which is preferably positioned to detect the temperature of the atmosphere near curtain door 2. In response to detecting temperatures in excess of a set temperature, the thermal switch signals the controller 42.

With reference to Figure 3, and with current reference to all the above Figures, the test switch 46 includes a contact 56 which is associated with a delayed de-energization of the electromagnet 40. Similarly, the reset / close switch 48 includes a contact 60 associated with the non-delayed de-energization of the electromagnet 40. The thermal switch 54 includes a bimetallic contact 62 which changes to its open state in response to the detection of a temperature in excess of a set temperature. Connected in series with the bimetallic contact 62 is an alarm contact 64 which is energizable by an alarm 66 (illustrated in Figure 1) connected to the controller 42.

The controller 42 includes a rectifier 68 that rectifies an incoming AC voltage 70 at rectified DC voltage. The rectifier 68 has a negative DC voltage terminal connected to a common node or ground 72 of the controller. Connected between a positive DC voltage terminal of the rectifier 68 and the common node 72 there is a supply side of a voltage regulator 74, a resistor 76 and a capacitor 78. In response to the reception of the rectified DC voltage of the rectifier 68, the voltage regulator 74 generates a DC voltage regulated on an output side, or load thereof. A negative terminal on the load side of the voltage regulator 74 is connected to the common node 72. A positive terminal on the load side of the voltage regulator 74 is connected to a terminal 80 of the contact 58 through the contact of the alarm 64, the bimetallic contact 62 of the thermal switch 54 and the contact 56 of the test switch 46. The green indicator lamp 50 is connected between a terminal 82 of the contact 58 and the common node 72. Connected between the normally closed contact 60 and the contact terminal 82 normally open 58 is the parallel combination of capacitor 84, coil CR1 and coil CR2.

The terminal 80 of the contact 58 is also connected to diode nodes 86 and 88. The cathode of the diode 86 is connected to a common terminal 90 of a relay RL1 which changes the state in response to the current flowing through the coil CRl. . In the normally closed state, the relay RL1 connects the terminal 80 of the contact 58 with the common node 72 through the red indicator lamp 52. However, in response to the current flowing through the coil CR1, the relay RL1 changes the state and connects terminal 80 of contact 58 to a terminal 82 of contact 58.

Connected in series between terminal 80 of contact 58 and common node 72 are resistors 98 and 100. Connected between resistor 98 and resistor 100 is a base terminal of a transistor TI having a transmitting terminal connected to common node 72 and a collector terminal connected to a base terminal of a transistor T2 through a resistor 102. Connected between the base terminal of the transistor T2 and the cathode of the diode 88 is a resistor 104. Connected between the base terminal of the transistor T2 and the common node 72 is the resistor 106. The transistor t2 has a transmitting terminal connected to the common node 72 and a transmitting terminal connected to a side of a coil CR3. A capacitor 108 is connected between the cathode of the diode 88 and the common node 72. A diode 110 has its anode connected to the cathode of the diode 88 and its cathode connects to a side coil CR3 opposite the collector terminal of the transistor T2.

A double-pole, double-load relay RL2, which responds to the current flowing in the coil CR2, is placed between the incoming voltage AC 70 and a rectifier 112 which converts the incoming voltage AC 70 into a DC voltage. The negative DC voltage terminal of the rectifier 112 is connected to the common node 72 and the DC positive voltage terminal of the rectifier 112 is connected to an anode of a diode 114. Connected between the positive terminal and the negative terminal of the rectifier 112 is a capacitor filter 116 which filters out any voltage fluctuations or small voltage fluctuations in the voltage output by the rectifier 112. Connected between a cathode of the diode 114 and the common node 72 is the hinge 38 that includes the electromagnet 140. Also connected between the cathode of the diode 114 and the common node 72 is the combination of series of a battery 118, a diode 120 and a bipolar double load relay RL3. The battery 118 has a negative terminal connected to the common node 72 and a positive terminal connected to the anode of the diode 120. The diode 120 has a cathode which is connected to one of the normally open terminals of the relay RL3. The cathode of diode 114 is connected to the other normally open terminal of relay RL3. The terminals of the relay RL3 not connected to the diodes 114 and 120 are connected together to form a node 122 which is connected to a node terminal of a diode 124. The diode 124 has a cathode terminal which is connected to the cathode terminal of the diode 110 , the anode terminal of a diode 126 and next to the coil CR3 opposite the collector terminal of the transistor T2. The diode 126 has a cathode terminal that is connected to the common terminal 90 of the relay RL1 through a resistor 128.

When the incoming voltage AC 70 is initially applied to the rectifier 68, the current does not flow through the coils CR1-CR3 and, therefore, the relays RL1-RL3 are in a normally closed state, as illustrated by solid lines in the Figure 3. The rectifier 68 converts the incoming voltage AC 70 into the DC voltage that is provided to the voltage regulator 74. The voltage regulator 74 converts the DC voltage of the rectifier 68 at DC regulated voltage that is provided to the key control station 44 through the contact of the alarm 64 and the bimetallic contact 62 of the thermal switch 54. The regulated AC voltage provided to the key control station 44 is provided to the red indicator lamp 52 through the contact 56 of the test switch 46, the diode 86 and the normally closed contact of the relay RLl. In response to the regulated DC voltage, the red indicator lamp 52 is illuminated thereby providing a visual indication of what incoming AC voltage 70 is provided to the controller 42.

The regulated DC voltage provided to the key control station 44 is also provided to the resistors 98 and 100. The cross voltage resistors 98, 100 direct the transistor TI into conduction whereby the potential in the common node 71 it is substantially impressed in the collector terminal of the transistor TI. The regulated AC voltage is also provided to the resistors 102, 104 and 106 through the diode 88. With the transistor ti in conduction, the resistors 102 and 104 are connected in parallel between the base terminal of the transistor T2 and the common node 72. The parallel connection of the resistors 102 and 106 in series with the resistor 104 gives the base terminal of the transistor T2 a pulse which is insufficient to direct the transistor t2 in conduction.

When it is desired to energize the electromagnet 40, the reset switch 48 is changed from a neutral position to a reset position which causes the contact 58 to be changed to the normally open state. With the contact 58 in the normally open state, the regulated DC voltage is provided to the coils CR1 and CR2 and to the capacitor 84. The regulated DC voltage provided to the coils CR1 and CR2 causes the DC current to flow through them to the coil. contact 60 and common node 72. The current flowing through coils CRl and CR2 causes the contacts of relays RLl and RL2 to change to the normally open state illustrated by dotted lines in Figure 3. With contact 58 and the relay RLl in the normally open state, the green indicator lamp 50 is illuminated by the regulated DC voltage. Similarly, changing the relay RL1 of the normally closed state isolates the red indicator lamp 52 from the regulated DC voltage by turning off the red indicator lamp 52.

Changing the relay RL2 to the normally open state connects the incoming voltage AC 70 with the rectifier 112. The rectifier 112 converts the incoming AC voltage 70 into a DC voltage that is provided to the electromagnet 40 through the diode 114. In response to the voltage supply DC of the rectifier 112, the electromagnet 40 produces a magnetic field that attracts the lower bar 18 placed closely adjacent to it. The magnetic attraction between the electromagnet 40 and the lower bar 18 is of sufficient force to keep the curtain 12 wound around the arrow 20. In the absence of the magnetic attraction between the electromagnet 40 and the lower bar 18, the weight of the curtain 12 is of sufficient degree that it causes the curtain 12 to unwind from the arrow 20 against the moment of the counterbalance 28.

When the relay RL1 changes to the normally open state, the reset reset switch 48 can be changed back to the neutral position by means of which the contact 58 changes to its normally closed state and the regulated DC voltage is not provided through of itself Thus, the contact 58, in response to the reset position of a reset reset switch 48, provides a momentary path for the regulated DC voltage to the green indicator lamp 50 and the CR1 and CR2 coils until the relay RL1 changes to the state normally open.

When it is desirable to close the door in normal operation, the reset reset switch 48 is switched from the neutral position to a closed position which causes the contact 60 to change to a normally open state thereby isolating coils CR1 and CR2, the capacitor 84 and the green indication lamp 50 from the common node 72. This isolation causes the current to cease in its flow through the coils CR1 and CR2 which causes the relays RL1 and RL2 to return to their normally closed state.

When the relay RL1 returns to its normally closed state, the red indicator lamp 52 is connected to the regulated DC voltage. Returning the relay RL2 to its normally closed state isolates the rectifier 112 from the incoming AC voltage. This isolation terminates the supply of DC voltage from the rectifier 112 to the electromagnet 40. In the absence of DC voltage, the electromagnet 40 is de-energized and the magnetic attraction between the electromagnet 40 and the lower bar 18 ends. In the absence of this magnetic attraction , the weight of the curtain 12 is sufficient to unwind the curtain 12 of the arrow 20 and close the opening 4. When the electromagnet 40 is de-energized, the reset reset switch 48 can be changed back to its neutral position by means of which contact 60 returns to its normally closed state. Thereafter, the curtain 12 can be raised by winding it around the arrow 20 and the reset reset switch 48 can be changed to the reset position to cause the magnetic attraction between the electromagnet 40 and the lower bar to be generated. 18, in the manner described above.

The controller 42 has a relay circuit 130 which includes resistors 98-106 and 128; the capacitors 84 and 108; the diodes 88, 110, 120, 124 and 126; the TI and T2 transistors; the CR3 coil; the relay RL3; and the battery 118. The relay circuit 130 delays the de-energization of the electromagnet 40 in response to isolate the relay circuit 130 from the voltage Regulated DC generated by the voltage regulator 74. The relay circuit 130 can be isolated from the regulated DC voltage by activating the test switch 46 thereby causing the contact 56 to be changed to the normally open state; activating the thermal switch 54 to open the contact 62; or activating the alarm 66 to open the alarm contact 64. Preferably, the alarm 66 is a fire alarm that causes the alarm contact 64 to open in response to detection of an alarm condition. The relay circuit 130 can also be isolated from the regulated DC voltage when the incoming AC voltage supply 70 is terminated.

When the relay circuit 130 is isolated from the regulated DC voltage, the transistor TI becomes non-conductive, the resistor 102 is isolated from the common node 72 and the capacitor 108 provides voltage to the resistors 104 and 106. The insulation of the resistor 102 of the node common 72 changes the loss of voltage across resistors 104 and 106 which causes the pulse to the base of transistor T2. This change in directions causes transistor T2 to conduct current from capacitor 108 through diode 110 and coil CR3.

The current flowing through coil CR3 causes relay RL3 to change to its normally open state illustrated in dotted lines in Figure 3.

To delay relays RL1 and RL2 on returning to their normally closed state in the absence of regulated DC voltage, capacitor 84 provides current to coils CR1 and CR2 until relay RL3 changes to its normally open state. When the relay RL3 changes to its normally open state, current flows from the rectifier 112 to the coils CR1 and CR2 through one of the relay poles RL3, the diodes 114, 124 and 126, the resistor 128 and the relay RL1. . With the relay RL3 in the normally open state, the rectifier 112 also provides current to the coil CR3 through a pole of the relay RL3 and the diodes 114, 124.

The orientation of the diode 110 allows the capacitor 108 to provide current to the coil CR3 to close the relay RL3. However, the voltage on the cathode side of the diode 110 is greater than the voltage on the anode side thereof. The foregoing is particularly true when the voltage across capacitor 108 has decreased in response to the supply of current to coil CR3 and resistors 104 and 106. When the voltage on the cathode side of diode 110 is greater than the voltage on the side anode, the capacitor 108 no longer supplies current to the CR3 coil. Therefore, the remaining charge in the capacitor 108 is used to drive the transistor T2 in conduction via the resistors 104 and 106.

When the capacitor 108 has been sufficiently discharged, the transistor T2 becomes non-conductive which isolates the coil CR3 from the common node 72 thereby terminating the current flow through the coil CR3. The absence of current flow through coil CR3 causes relay RL3 to return to its normally closed state which isolates coils CR1 and CR2 and relay circuit 130 from rectifier 112. Isolation of coils CR1 and CR2 of the rectifier 112 terminates the current flow through coils CRl and CR2 which causes relays RLl and RL2 to return to their normally closed state. The return of the relay RL2 to its normally closed state isolates the rectifier 112 from the incoming voltage AC 70 thereby terminating the current flow through the electromagnet 40. The absence of current flowing through the electromagnet 40 terminates the magnetic attraction between the electromagnet 40. and the lower bar 18. Because the weight of the door is sufficient to overcome the moment applied to the arrow 20 by means of the counterbalance 28, the door goes down to a closed position.

If the relay circuit 130 changes the relay RL3 to its normally open state in response to the termination of the incoming AC voltage supply 70, the battery 118 supplies current to the CR3 coil via the diodes 120, 124 and the relay pole RL3 placed between them. The battery 118 also supplies current to the electromagnet 40 through the diode 120 and the poles of the relay RL3 and supplies current to the coils CR1-CR2 through the diodes 120, 124, 126, the resistor 218 and the relays RL1 and RL3. Thus, in the absence of the incoming AC 70 voltage, the battery 118 supplies current to the coils CR1-CR3 and the electromagnet 40 until the voltage across the capacitor 108 decreases enough to cause the transistor T2 to become non-conductive.

In a preferred instance, the capacitor 108 stores enough charge to delay the de-energization of the electromagnet 40 during a desired delay interval, for example, 10 seconds. Similarly, the capacitor 84 stores enough charge to maintain current flow to the CR1 and CR2 coils during a sufficient interval for the relay RL3 to change to the normally open state so that the current is supplied to the CR1 and CR2 coils through of the same.

If, while the transistor T2 is conducting, the regulated DC voltage is reapplied to the relay circuit 130, the delayed de-energization of the electromagnet 40 will be terminated and the magnetic attraction between the electromagnet 40 and the lower bar 18 will continue without interruptions.

Based on the foregoing, it can be seen that the relay circuit 130 allows power to be supplied to the electromagnet 40 during a delay interval, for example, 10 seconds, after the relay circuit 130 is isolated from the regulated DC voltage generated. by the voltage regulator 74. The regulated DC voltage can be isolated from the relay circuit 130 by switching to the normally open state 54 of the test switch 46, the opening contact 62 of the thermal switch 54 or the opening contact 64. related to the alarm 66. Moreover, when the incoming AC voltage supply 70 is terminated, the relay circuit 130 operates to maintain the energizing current to the electromagnet 40 during the delay interval. A) Yes, the weight of the door acting to unwind the curtain 12 of the arrow 20 can be delayed under undesirable temperature, alarm or test conditions or when the incoming AC voltage supply 70 is terminated. Moreover, the present invention provides a door retention system which in normal use can retain a door that opens vertically open and that allows the immediate closing of the door.

The invention has been described with reference to the preferred specimen. Modifications and obvious alterations will occur to others after reading and understanding the present description. For example, two or more electromagnets 40 can be used, two or more bimetallic contacts 62 or two or more alarm contacts 64 can be used as required by the application. Moreover, while it was described in relation to a curtain door, the controller can also be used with other types of doors that open vertically, such as a curtain door or a conventional parking door. It is intended that the invention be construed as including all such modifications and alterations thereof as long as they fall within the scope of the appended claims or the equivalents thereof.

Claims (21)

1. CLAIMS: 1. A curtain door comprising: a pair of guides placed in separate relation, each guide has a receiving slot therein; a curtain having a plurality of flanges and a lower bar, each flange having at least one side thereof secured rotatably with one side of an adjacent flange and having the opposite ends thereof receivable in the receiving slots of the pair of flanges. guides, the lower bar has one side thereof connected to one side of a last flange of the curtain and has opposite ends thereof received in the receiving slots of the pair of guides; an arrow placed perpendicular to the longitudinal axes of the pair of guides adjacent to one end thereof, the arrow connected to one side of one of the plurality of flanges of the curtain opposite the lower bar, the arrow rotating about a longitudinal axis of the same so that the curtain can be wound around the arrow; a contrablance connected to the arrow and applying to it a force that partially opposes a weight of the curtain that resists the rolling of the curtain around the arrow; a hinge placed adjacent to the arrow to be coupled to one of the lower bar and the end of the curtain adjacent to the lower bar when the curtain is wrapped around the arrow, the hinge coerces with one of the lower bar and the end of the curtain adjacent to it to secure the curtain rolled around the arrow; and a controller connected to the hinge, the controller selectively causes the hinge to release one from the lower bar and the end of the curtain adjacent thereto so that the weight of the curtain causes the curtain to unwind from the arrow.
2. 2. The revolving door as set forth in claim 1, wherein: the hinge includes an electromagnet energizable by the controller to produce a magnetic attraction between the electromagnet and one of the lower bar and the end of the curtain adjacent to the lower bar; and a reset switch connected to the controller and activatable to cause current to be supplied to the electromagnet.
3. 3. The curtain door as set forth in Claim 2, which further includes a closing switch connected to the controller and activatable to terminate the current supply to the electromagnet.
4. 4. The curtain door as set forth in Claim 2, further comprising: at least one of a test switch, a thermal switch and an alarm switch; and a relay circuit connected to the electromagnet and responding to the activation of at least one of the test switches, the thermal switch and the alarm switch to terminate the current supply to the electromagnet after a delay interval.
5. 5. The curtain door as set forth in Claim 4, wherein two or more of the test switches, the thermal switch and the alarm switch are connected in series between the relay circuit and a voltage source.
6. 6. The curtain door as set forth in Claim 4, further comprising: a rectifier for rectifying the incoming AC voltage to a DC voltage used to supply current to the electromagnet; and a battery connected to the power supply to the relay circuit and the electromagnet in response to the termination of the incoming AC voltage supply.
7. 7. The curtain door as set forth in the Claim, wherein the counterbalance is a bellows spring for applying a torque connected between the arrow and a rigid support.
8. 8. A door retention system for retaining a door that opens vertically open, the restraint system comprising: an operable electrical hinge positioned to secure the door that opens vertically open; a controller connected to the hinge to control the action of the hinge to secure the door open, the controller includes a relay circuit; and a reset switch connected to the controller, wherein: the controller causes power to be supplied to the hinge in response to activation of the reset switch; the hinge activates and secures the open door in response to the current applied to the hinge; the relay circuit removes the current from the hinge after a delay interval; and removing the current from the hinge causes the hinge to release the door.
9. 9. The system for retaining the door as set forth in Claim 8, wherein the delay interval of the relay circuit is initiated in response to the termination of an incoming AC voltage supply.
10. 10. The door retaining system as set forth in Claim 8, further including at least one of: a closing switch connected to the controller and operable to terminate the supply of current to the hinge; a thermal switch connected to the controller and activatable in response to feeling a temperature in excess of a set temperature; an alarm switch connected to the controller and activated in response to an alarm; and a test switch connected to the controller wherein the activation of at least one of the thermal switches, the alarm switch and the test switch initiates the start of the relay circuit delay interval.
11. 11. The door retaining system as set forth in Claim 8, further comprising: a battery connectable by the relay circuit to provide current to the hinge during the delay interval.
12. 12. The door retainer system as set forth in Claim 10, further including a rectifier that converts the incoming AC voltage to a DC voltage used to provide the current to the hinge.
13. 13. The door retaining system as set forth in Claim 8, wherein the hinge includes an electromagnet that is energizable to produce a magnetic attraction between the electromagnet and a door.
14. 14. The system for retaining a door as set forth in Claim 10, wherein the alarm is a fire alarm.
15. 15. A method for controlling a door that opens vertically, the method comprises the steps of: (a) raising the door that opens vertically to an open position, said door connected to a counterbalance that partially opposes a weight of the door that resists the opening thereof; (b) energizing an electrically operable hinge to secure the door in the open position; (c) detecting at least one of: (i) a temperature in excess of a desired temperature; (ii) the activation of an external alarm; and (iii) the activation of a switch; and (d) deenergizing the hinge in response to the detection of (c) (i), (c) (ii) or (c) (iii), wherein the de-energization of the hinge allows the weight of the door to drive the door to a closed position.
16. 16. The method for controlling the door that opens vertically as set forth in Claim 15, wherein the hinge includes an electromagnet that is energizable by means of a current to produce between the electromagnet and the door a magnetic attraction that secures the door open.
17. 17. The method for controlling the door that opens vertically as set forth in Claim 16, wherein step (b) includes the step of activating a reset switch to cause current to flow to the electromagnet.
18. 18. The method for controlling the door that opens vertically as set forth in Claim 15, wherein step (d) includes the step of delaying the de-energization of the hinge during a delay interval after detecting the at least one of (c) ) (i), (c) (ii) or (c) (iii).
19. 19. The method for controlling the vertically opening door as set forth in Claim 16, further comprising the steps of: converting the incoming AC voltage to a DC voltage used to supply the current used to energize the hinge; and delaying the de-energization of the hinge during a delay interval in response to the termination of the incoming AC voltage supply.
20. 20. A vertically opening door comprising: a vertically opening door extending between the sides of an opening; a spring connected to provide a force that partially opposes a weight of the door that resists the vertical opening thereof; an electrically operable hinge; and a controller connected to the electrically operable hinge to provide a current thereto which causes the electrically actuable hinge to secure the door in a vertically open position, wherein the absence of the electrically operable hinge that secures the door vertically open the weight of the door pushes the door to a closed position.
21. 21. The door that opens vertically as set forth in Claim 20, wherein the electrically operable hinge is an electromagnet that is energizable by means of the controller to produce a magnetic attraction between the door and the electromagnet. EXCERPT OF THE INVENTION A fire curtain door includes a door opening / sustained opening system that includes an electromagnet that is energized by a controller when the door is in the open position. The energized magnet magnetically attracts a bottom bar of the curtain door to secure the door in the open position. A key control station connected to the controller allows the electromagnet to be energized when the door is in the open position and which allows the controller to de-energize the electromagnet so that the weight of the door causes the door to close. The key control station also includes a test switch that allows the controller to de-energize the electromagnet after a delay interval. The controller also deenergizes the electromagnet after a delay interval in response to the activation of an alarm or in response to a thermal switch that feels a temperature in excess of a set temperature.