Technical Field

The present invention relates to a fire protection system, and more particularly, to the improvement of an automatic fire door release apparatus.

Background Art

In accordance with the provision of the Fire Services

Act, doors at an emergency stair, an emergency elevator, or a region for eliminating smoke in a platform must employ a fire door for preventing the spread of fire in a building. The automatic door closing device, such as door closer or an auto hinge, for preventing the spread of flames in fire is installed on the fire door, and an automatic fire door release apparatus is installed on the fire door or a sidewall of the fire door. The automatic fire door release apparatus serves to maintain the opened state of the fire door in a normal state, and to release the latching of the fire door in the opened state by a designated controlling method when fire is generated.

In the fire door, which is provided with the automatic fire door closing device and the automatic fire door release

apparatus, the opened state of the fire door is normally maintained. When fire is generated, the automatic fire door release apparatus is operated by a fire detector to release the latched state of the fire door, and the fire door is closed by the closing power of the automatic fire door closing device, thereby preventing the spread of smokes, noxious gas, or flames due to the fire. At this time, the closed state of the fire door must be maintained, but must not be converted into the latched state. Thus, persons push and open the fire door, and safely escape from a fire spot through an emergency exit. The fire door, which was opened by the persons, is closed again by the closing power of the automatic fire door closing device, such as the door closer, thereby preventing the spread of the smokes or flames. Automatic fire door release apparatuses are largely divided into mechanical fire door apparatuses and electric fire door release apparatuses. Further, the mechanical fire door release apparatuses are divided into a magnetic fire door release apparatus and a solenoid fire door release apparatus according to their driving methods.

The magnetic fire door release apparatus is configured such that it is supported by a permanent magnet and operated by an electric manipulation, and has an absorptive power of 10kg ^• f, a rated voltage of DC 24V, and a rated current of 80OmA. The solenoid fire door release apparatus is configured such that a hook is released by the operation of a solenoid,

has a working voltage of DC 24V, an operating current of approximately 200~400mA, which is different based manufacturers, and an absorptive power of 30±5kg ^# f.

One example of the solenoid fire door release apparatus is a hook and latch door release of a model No. S-200 produced by SNC metal Corp. The above hook and latch door release has a working voltage of DC 24V±20%, an operating current of 350mA±20%, , and a bearing capacity of 25±3kg- f. Here, the bearing capacity of the hook and latch door release is adjustable in the range of 15~70kg'f. In order to prevent the hook and latch door release from re-latching, a mechanical method is used. The mechanical re-latching prevention method has been recently employed by the above hook and latch door release of the model No. S-200, but are not employed by other models produced by other companies.

In the case that the solenoid fire door release apparatus is employed, the solenoid fire door release apparatus requires means for adjusting a holding power according to the size of a fire door and the closing power of an automatic door closing device, and means for preventing the re-latching thereof. Further, the solenoid fire door release apparatus consumes an operating current of several hundreds of mA so as to release the latching of the hook.

In order to satisfy all requirements of the solenoid fire door release apparatus, production costs of the solenoid fire door release apparatus are increased, and it is

impossible to release the hand-operated latching or it is difficult to release the hand-operated latching if possible. The most sensitively considered matter by fire protection companies is the amount of consumed current. In the case that current of several hundreds of mA is consumed so as to operate a single fire door, a battery having a large capacity is required in consideration of operations of other fire protection systems. Since the battery is a product to be consumed and has a high price, the capacity of the battery highly influences the production costs of products.

Accordingly, an automatic fire door release apparatus, which has low production costs and excellent reliability, is operable using a small amount of current, allows the latching thereof to be released by hand, prevents the re-latching thereof, and has a simple structure.

Disclosure of Invention

Technical Problem

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an automatic fire door release apparatus, which has low production costs and excellent reliability.

It is a further object of the present invention to

provide an automatic fire door release apparatus, which is operable using a small amount of current, and allows the latching thereof to be released by hand.

It is another object of the present invention to provide an automatic fire door release apparatus, which assures power for holding the latching of the door regardless of the size or weight of a fire door, and prevents the re-latching thereof, and has a simple structure.

It is another object of the present invention to provide a motor-type automatic fire door release apparatus.

It is yet another object of the present invention to provide an automatic fire door release apparatus, which satisfies the regulations of the Fire Services Act regarding rated voltage, is operable at low current, and is embodied as a small-sized motor.

Technical Solution

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a fire door release apparatus comprising: a fixture installed on a side wall of a fire door; and a latch installed on the fire door, wherein an adjuster-connecting tube is inserted into and simultaneously latched on a driving shaft rotated by a reduction motor of the fixture, and the adjuster-connecting tube is released from the driving shaft by

the rotation of the reduction motor.

In accordance with another aspect of the present invention, there is provided a fire door release apparatus comprising: first and second fixtures respectively installed on side walls of first and second fire doors having a dual- gate structure; first and second latches respectively installed on the first and second fire doors, adjuster- connecting tubes of which are respectively inserted into and simultaneously latched on driving shafts rotated by first and second reduction motors of the first and second fixtures; and a circuit unit for releasing the latching of the second fixture by the stoppage of the rotation of the first reduction motor and the rotating operation of the second reduction motor, after the latching of the first fixture is released by the rotation of the first reduction motor due to the supply of a starting voltage when fire is sensed.

The fire door release apparatus of the present invention is an apparatus, for performing latching and releasing of the fire door, which maintains the latched state of the fire door under the condition that the fire door is opened, and releases the latched state of the opened fire door when the latching the fire door is released.

Advantageous Effects

The automatic fire door release apparatus of the present

invention is used by a fire protection system, and more particularly, is installed on fire doors at an emergency stair, an emergency elevator, or a region for eliminating smoke in a platform, thereby serving to prevent the spread of fire.

Description of Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 illustrate an automatic fire door release apparatus in an installed state in accordance with one embodiment of the present invention, and more particularly, FIG. 1 is an external view of the automatic fire door release apparatus and FIG. 2 is a transverse sectional view of the automatic fire door release apparatus;

FIG. 3 is an exploded perspective view of the automatic fire door release apparatus in accordance with one embodiment of the present invention;

FIG. 4 is a partial assembled perspective view of the automatic fire door release apparatus in accordance with one embodiment of the present invention; FIG. 5 is a sectional view of a fixing board of a fixture;

FIG. 6 is a longitudinal sectional view of the automatic fire door release apparatus in a latching state;

FIG. 7 is a longitudinal sectional view of the automatic fire door release apparatus of the present invention in a releasing state;

FIG. 8 is a longitudinal sectional view of the automatic fire door release apparatus of the present invention after the releasing state;

FIGS. 9 to 11 are respective schematic views of circuit units of the automatic fire door release apparatus in accordance with one embodiment of the present invention;

FIG. 12 is a plan view of an adjuster of a latch, having the surface, on which identification data are engraved; and FIG. 13 is a partial assembled perspective view of an automatic fire door release apparatus in accordance with another embodiment of the present invention.

Best Mode for Carrying Out the Invention

Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings.

In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description of the present invention, a detailed description of known functions

and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Automatic fire door release apparatuses in accordance with the preferred embodiments of the present invention are motor-type automatic fire door release apparatuses, which are prevented from re-latching and are closed by hand without using power when persons evacuate them, and operate a motor using a relatively small amount of current. Although fire doors having a dual-gate structure and a

DC motor using a voltage of 12V to 24 V are applied to the automatic fire door release apparatuses in accordance with the preferred embodiments of the present invention, which will be described later, the present invention is not limited thereto. FIGS. 1 and 2 illustrate an automatic fire door release apparatus in an installed state in accordance with one embodiment of the present invention, and more particularly, FIG. 1 is an external view of the automatic fire door release apparatus and FIG. 2 is a transverse sectional view of the automatic fire door release apparatus.

FIG. 3 is an exploded perspective view of the automatic fire door release apparatus in accordance with one embodiment of the present invention. FIG. 4 is a partial assembled perspective view of the automatic fire door release apparatus 10 in accordance with one embodiment of the present invention, and FIG. 5 is a sectional view of a

fixing board 24 of a fixture 12. FIG. 6 is a longitudinal sectional view of the automatic fire door release apparatus 10 in a latching state.

FIGS. 1 and 2 illustrate fire doors 2a and 2b having the dual-gate structure.

The fire doors 2a and 2b having the duel-gate structure are installed such that they are opened from the inside to the outside according to the Fire Services Act and an automatic door closing devices 4a and 4b, such as door closers or auto hinges, are respectively installed at the fire doors 2a and 2b. In this embodiment of the present invention, the automatic door closing devices 4a and 4b are door closers.

In order to open the fire doors 2a and 2b, the second fire door 2b must be first opened and then the first fire door 2a must be opened. On the other hand, in order to close the fire doors 2a and 2b, the first and second fire doors 2a and 2b must be closed in the reverse order. That is, the first fire door 2a must be first closed and then the second fire door 2b must be closed. A circuit unit (with reference to FIGS. 9 to 11) serves to perform the above opening and closing operations of the first and second fire doors 2a and 2b. Thereby, gaps are not generated between the first and second fire doors 2a and 2b, thus preventing smokes and noxious gas from leaking through the gaps. Further, in terms of the circuit unit, the releasing of the latching of the

first and second fire doors 2a and 2b is sequentially performed, thereby reducing a load by half compared to the load when the releasing of the latching of the first and second fire doors 2a and 2b is simultaneously performed. The automatic fire door release apparatus 100 in accordance with this embodiment comprises fixtures 12 respectively installed on sidewalls of the fire doors 2a and 2b, and latches 14 respectively installed on the fire doors 2a and 2b. Here, an adjuster-connecting tube 66 is inserted into and simultaneously latched on a driving shaft rotated by a reduction motor 30 of the fixture 12, and the adjuster- connecting tube 66 is released from the driving shaft by the rotation of the reduction motor 30.

The fixture 12 and the latch 14, as shown in FIG. 1, are installed at a height at which a general door fastener is provided on a door.

Hereinafter, the configuration of the automatic fire door release apparatus 10 in accordance with one embodiment of the present invention will be described in more detail. An installer installs the fixture 12 in a rectangular groove,- which is previously formed in an outer sidewall according to the regulations of the Fire Services Act. In the case that the rectangular groove is not formed in the outer sidewall, the installer digs the rectangular groove in the sidewall 6. The fixture 12 may be completely buried under the sidewall 6, or be partially protruded from the

surface of the sidewall 6 according to states of the fire doors 2a and 2b. The height of the surface of the fixture 12 is adjusted by three surface height-adjusting bolts 40 fixed to upper and lower portions of a bracket 20, as shown in FIG. 4. The adjustment of the height of the surface of the fixture 12 using the surface height-adjusting bolts 40 is well known to those skilled in the art, and a detailed description thereof will thus be omitted because it is considered to be unnecessary. Now, the configuration of the fixture 12 of the automatic fire door release apparatus 10 in accordance with one embodiment of the present invention will be described.

The reduction gear 30 including a DC motor 26 and a reduction gear 28 is installed between the bracket 20 of the fixture 12 and a fixing board 24 installed on a support plate 22. Preferably, the bracket 20, the support plate 22, and the fixing board 24 are integrally formed by die- casting.

Since a fixing piece 29 extended to the outer circumference of the reduction motor 30 is connected to the reduction motor 30 through connection holes 33a and 33b formed through the fixing board 24 using fixing bolts 31a and 31b and fixing nuts, the reduction motor 30 is installed on the rear part of the fixing board 24. The connection holes 33a and 33b passing the fixing bolts 31a and 31b have a ^Xλ +"-shaped section. Further, a driving shaft hole 25

formed through the fixing board 24 has a comparatively large size or has a ^λλ +"-shaped section, thereby allowing the installer to voluntarily adjust the fixed position of a driving shaft of the reduction motor 30 up and down and left and right, if necessary.

The terminal of the driving shaft of the reduction motor 30 passes through the driving shaft hole 25 of the fixing board 24, and is integrally connected to a driving connection rod 32 by a pin. The driving connection rod 32 is a square pillar, or may be a polygonal pillar such as a triangular pillar or a hexagonal pillar. Further, the driving connection rod 32, as shown in FIG. 13 in accordance with another embodiment of the present invention, may be a cylinder having a protrusion 300 formed on the surface thereof.

A latching piece 34 is located below the driving connection rod 32 and installed on the support plate 22. The latching piece 34 has a structure such that a protruding rod 64 of the adjuster-connecting tube 66 is locked in the latching piece 34. The latching piece 34 having a rectangular shape is installed in a longitudinal direction, and the rear surface of the latching piece 34 is finished so that a slip surface is defined thereon. Thereby, friction of rotation between the protruding rod 64 of the adjuster- connecting tube 66, which is locked in the latching piece 34, and the latching piece 34 of the adjuster-connecting

tube 66 is minimized.

A contact switch 36 is installed at one side of the front end of the support plate 22. The contact switch 36 includes an operating flap 37 on the front surface thereof, and three terminals 84, 86, and 88 on the rear surface thereof. Here, reference numeral "86" represents a starting terminal, reference numeral "84" represents a common terminal, and reference numeral "88" represents a checking terminal, to which battery power (B ⁺ ) is applied through a releasing display lamp (90 of FIGS. 9 to 11) . For example, a three-contact point micro switch may be used as the contact switch 36.

When the driving connection rod 32 of the fixture 12 is inserted into a connection groove 60 of the latch 14 and the protruding rod 64 is latched on the latching piece 34, the operating flap 37 of the contact switch 36 is pushed by a flange portion 62 of the adjuster-connecting tube 66 and contacts the side surface of the flange portion 62.

A fixture cover 35 includes an operating hole 38 formed therethrough for passing the adjuster-connecting tube 66 of the latch 14. The cover 35 is fixed to the bracket 20 by bolts 39, thereby being integrally assembled with the bracket 20.

The installer fixes the bracket 20 of the fixture 12 to the installation groove formed in the side wall 6 using the surface height-adjusting bolts 40, thereby installing

the fixture 12 on the wall. If necessary, the installer adjusts the height of the surface of the fixture 12 using the surface height-adjusting bolts 40. The adjustment of the height of the surface of the fixture 12 using the surface height-adjusting bolts 40 is well known to those skilled in the art, and a detailed description thereof will thus be omitted because it is considered to be unnecessary.

The DC motor 26 installed in the fixture 12 uses a rated voltage of 6V to 24V. For example, when the DC motor 26 is employed to use a rated voltage of 6V to 12V, the DC motor 26 can have a small size. However, since the rated voltage of fire protection systems is 24V, the DC motor 26 requires a regulator for down-converting input voltage into voltage of 6V to 12V. In the case that the DC motor 26 has a rated voltage of DC 24V in accordance with the embodiment of the present invention, the DC motor 26 has electrical characteristics, such as a working voltage of 10~24V, a rated load of 2kg ^• cm, a current, when unloading, of less than 25mA, a current, when loading, of less than 4OmA, a rotational frequency, when unloading, of 90±3rpm(Revolutions per Minute), a rotational frequency, when loading, of more than 80rpm, a stall torque load of 4kg ^• cm, and a torque current of 35OmA. Preferably, the reduction gear ratio of the reduction motor 30 including the DC motor 26 and the reduction gear 28 is 1:122.

Further, in the case that the DC motor 26 has a rated

voltage of DC 12V, the DC motor 26 has electrical characteristics, such as a working voltage of 6-12V, a rated load of 2kg ^• cm, a current, when unloading, of less than 15mA, a current, when loading, of less than 35mA, a rotational frequency, when unloading, of 86±3rρm(Revolutions per Minute) , a rotational frequency, when loading, of more than 70rpm, a stall torque load of 2kg ^• cm, and a torque current of 20OmA. Preferably, the reduction gear ratio of the reduction motor 30 including the DC motor 25 and the reduction gear 28 is 1:122. Preferably, the reduction gear ratio of the reduction motor 30 including the DC motor 26 and the reduction gear 28 is 1:69.95.

When the DC motor 26 has a rated voltage of DC 12V, since the starting voltage (output voltage) of a fire detector is 24V, the DC motor 26 must require the regulator for down-converting the voltage. An inventor of the present invention notices that it is not necessary to continuously operate the DC motor 26 in accordance with the embodiment of the present invention for several tens of hours or several hours but it is just necessary to operate the DC motor 26 within several seconds (for example, 0.2. to 2 seconds) such that the DC motor 26 can be rotated only by 90°. Therefore, it is possible to manufacture a DC motor, which uses a rated voltage of 24V while having a size smaller than that of a universal motor.

In the case that the regulator for down-converting and stabilizing the voltage is used, a non-polar circuit for protecting the regulator is provided as shown in FIGS. 9 to 11. FIGS. 9 to 11 are respective schematic views of circuit units of the automatic fire door release apparatus 10 in accordance with one embodiment of the present invention. FIG. 9 is a circuit diagram when the automatic fire door release apparatus 10 is installed on the fire doors 2a and 2b having a dual-gate structure and employs the DC motor 26 using a rated voltage of 6V to 24V, FIG. 10 is a circuit diagram when the automatic fire door release apparatus 10 is installed on the fire doors 2a and 2b having a dual-gate structure and employs the DC motor 26 using a rated voltage of 24V, and FIG. 11 is a circuit diagram when the automatic fire door release apparatus 10 is installed on a fire door having a single-gate structure and employs the DC motor 26 using a rated voltage of 24V.

First, with reference to FIG. 9, a circuit unit of the automatic dual-structure fire door release apparatus 10 having a regulator 82 includes a contact switch 83 and voltage-adjusting portions 80a and 80b.

The contact switch 83 includes a starting terminal 86, a common terminal 84, a checking terminal 88, and first and second switch portions SWl and SW2. The first and second switch portions SWl and SW2 are complementarily switched.

That is, when the operating flap 37 of the contact switch 83, as shown in FIGS. 3 and 4 is pushed, the first switch portion SWl is turned on and the second switch portion SW2 is turned off. Then, when the operating flap 37 is distant from a contact point, the first switch portion SWl is turned off and the second switch portion SW2 is turned on.

Hereinafter, the circuit-connecting structures of the contact switches 3β of each of the first and second fire doors 2a and 2b will be described. The starting voltages (+) and (-) of a fire detector, such as a smoke detector, are respectively applied to the starting terminal 86 and the common terminal 84 of the contact switch 36. The starting terminal 86 is connected to a node between diodes Dl and D2 of a non-polar circuit 81, the common terminal 84 is connected to a common contact point b of the first and second switch portions SWl and SW2 of the contact switch 36, and the checking terminal 88 is connected to a contact point c of the second switch portion SW2.

In the contact switch 36 of the second fire door 2b, the common terminal 84 of the second fire door 2b is connected to the checking terminal 88 of the first fire door 2a, and the positive starting voltage (+) of the fire detector is applied to the starting terminal 86 of the second fire door 2b. The battery voltage (B+) is applied to the checking terminal 88 of the second fire door 2b through the releasing display lamp 90.

In a state in which the starting voltage of the fire detector is applied, a closed loop is formed only when the first switch portion SWl is turned on, i.e., the operating flap 37 of the contact switch 83 is pushed, thereby operating the DC motor 26 of the first fire door 2a. Here, since the second switch portion SW2 of the contact switch 36 of the first fire door 2a is turned off, a closed loop is not formed, thereby not operating the DC motor 26 of the second fire door 2b. When the first fire door 2a, which was maintained in an opened state by means of the automatic fire door release apparatus 10, is converted into a released state, the operating flap 37 of the contact switch 36 is detached from the contact point so that the first switch portion SWl of the contact switch 36 is turned off and the second switch portion SW2 of the contact switch 36 is turned on. Consequently, the operation of the DC motor 26 of the first fire door 2a is stopped, and the DC motor 26 of the second fire door 2b starts operation. When the automatic fire door release apparatus 10 of the second fire door 2b is operated by the operation of the DC motor 26 of the second fire door 2b, the latched state of the second fire door 2b is released. When the latched state of the second fire door 2b, which was maintained in an opened state by means of the automatic fire door release apparatus 10, is released, the operating flap 37 of the

contact switch 36 of the second fire door 2b is detached from the contact point so that the first switch portion SWl of the contact switch 36 is turned off and the second switch portion SW2 of the contact switch 36 is turned on. When the first switch portion SWl is converted into the off state, the operation of the DC motor 26 of the second fire door 2b is stopped.

When the first and second fire doors 2a and 2b are sequentially closed after the latched state of the first fire door 2a and the latched state of the second fire door 2b are sequentially released, the second switch portions SW2 of the contact switches 36 of the first and second fire doors 2a and 2b are turned on. Accordingly, a closed loop, in which the battery power (B+) is connected to the negative starting voltage (-) of the fire detector through the releasing display lamp 90, the second switch portion SW2 of the second fire door 2b, the common node 84, the second switch portion SW2 of the first fire door 2a, and the common node 84, is formed, thereby emitting the releasing display lamp 90.

The releasing display lamp 90 is emitted after the releasing of the latching of the automatic fire door release apparatus 10 is completely performed. Thereby, a supervisor can confirm that the releasing of the latched states of the corresponding first and second fire doors 2a and 2b is completely achieved.

In FIG. 9, each of the voltage-adjusting portions 80a and 80b includes the regulator 82 for down-converting and/or stabilizing the voltage such that the input voltage of 24V is converted into the motor-driving rated voltage of 6V to 24V, and the non-polar circuit 81 for protecting the regulator 82 when polarities of the power are reversed.

The non-polar circuit 81, which includes the diodes Dl to D4, allows the positive power (+) to be applied to an input terminal of the regulator 82 even when the polarities of the power applied to the starting terminal 86 and the common terminal 84 are reversed. The regulator 82 down- converts and stabilizes the input voltage of 24V into the voltage of 6V to 24V, and then applies the regulated voltage to the DC motor 26. In FIG. 9, a capacitor Cl serves to eliminate peak noise.

Preferably, the voltage-adjusting portions 80a and 80b in FIG. 9 are installed in a clearance on the support plates 22 of the fixtures 12 of the first and second fire doors 2a and 2b.

The configuration of the circuit unit of FIG. 10 is the same as that of the circuit unit of FIG. 9 except that the circuit unit of FIG. 10 does not include the voltage- adjusting portions 80a and 80b. That is, in FIG. 10, ends of the nodes Nl and N2 are connected directly to both ends of the DC motor 26.

The circuit unit of FIG. 11 is configured such that the battery voltage (B ⁺ ) is connected directly to the checking terminal 88 through the releasing display lamp 90.

The configurations of the circuit units, as shown in FIGS. 9 to 11, are advantageous in that the latching of the fire doors and the releasing of the latching of the fire doors are reliably secured through the releasing display lamp 90. Further, since the second fire door 2b is closed after the closing of the first fire door 2a is completed, the circuit units serve as an adjustor for adjusting mechanical priority of the first and second fire doors 2a and 2b, and distribute current load by means of the sequential operations of the motors of the first and second fire doors 2a and 2b. With reference to FIGS. 1 to 6 again, after the fixtures 12 are installed, an external cover (41 in FIG. 6) covers each of the side walls 6a and βb. Here, the cover 35 is slightly protruded from a through hole of the external cover 41, as shown in FIG. 6. Thereafter, the installer forms through holes through the first and second fire doors 2a and 2b, and installs the latches 14 therein.

More specifically, a disk type inner supporter 56 and a disk type outer supporter 58 of the latch 14 are connected by supporting rods 48 using screws 44 and 46, and the connected inner and outer supporters 56 and 58 are fixed to

the first and second fire doors 2a and 2b. The configuration of a supporting portion including the inner and outer supporter 56 and 58 and the supporting rods 48 may be variously modified. Thereafter, an axial rod 52 of an adjuster 50 passes through the through holes of the first and second fire doors 2a and 2b and the through holes of the inner and outer supporters 56 and 58, and the adjuster-connecting tube 66 including the flange portion 62, the connection groove 60, and the protruding rod 64 is connected to a front end of the axial rod 52, thereby assembling the latch 14. The driving connection rod 32 of the fixture 12 is inserted into the connection groove 60 of the adjuster-connecting tube 66. The protruding rod 64 of the adjuster-connecting tube 66 is installed at one side of the outer surface of a front end of the adjuster-connecting tube 66, and has a cylindrical structure. The protruding rod 64 is latched on the latching piece 34 of the fixture 12. In order to minimize friction between the protruding rod 64 and the latching piece 34 when the latching of the protruding rod 64 onto the latching piece 34 is released, a portion of the protruding rod 64 contacting the latching piece 34 is finished such that the portion defines a slip surface. The cylindrical structure of the protruding rod 34 minimizes a contact area with the latching piece 34.

The adjuster 50 has a rectangular structure such that

the rear end of the adjuster 50 is extended in a designated direction. The above rectangular structure of the adjuster 50 allows a user to easily recognize that the automatic fire door release apparatus 10 is now in a latching state or releasing state. In the embodiment as shown in FIG. 3, when the adjuster 50 is erected in a vertical state, the automatic fire door release apparatus 10 represents the latching state, and when the adjuster 50 is rotated in the clockwise or counterclockwise direction and laid in a horizontal state, the automatic fire door release apparatus 10 represents the releasing state.

As shown in FIG. 12, identification data, such as "releasing" and "latching", are engraved on the surface of the adjuster 50. Preferably, a mark indicating the position of the protruding rod 64 is engraved and marked with a red color source 92.

An adjuster hand lever 54 having a crescent shape is installed at the outer ends of the adjuster 50 having the rectangular structure, such that the adjuster hand lever 54 can be turned pivotally. The adjuster hand lever 54 is used by the user when the user wants to open or close the first and second fire doors 2a and 2b or to adjust the latches 14.

The above-described automatic fire door release apparatus 10 in accordance with one embodiment of the present invention has a simple structure, and comparatively low production costs compared to a conventional solenoid-

driven release apparatus. Further, the automatic fire door release apparatus 10 does not require any additional device for adjusting holding power, and does not generate problems or operating errors, thereby having high reliability. FIG. 7 is a longitudinal sectional view of the automatic fire door release apparatus 10 in a releasing state, and FIG. 8 is a longitudinal sectional view of the automatic fire door release apparatus 10 after the releasing state. In order to latch the first and second fire doors 2a and 2b on the automatic fire door release apparatuses 10, the second fire door 2b is first opened so that the latch 14 of the second fire door 2b is latched on the fixture 12 installed on the side wall βb corresponding to the second fire door 2b, and the first fire door 2a is then opened so that the latch 14 of the first fire door 2a is latched on the fixture 12 installed on the side wall 6a corresponding to the first fire door 2a.

Then, the user pushes second fire door 2b outwardly, thereby causing the fixture 14 installed on the second fire door 2b to be close to the fixture 12 installed on the side wall 6b corresponding to the second fire door 2b. Thereafter, the user pushes the second fire door 2b under the condition that the "releasing" state of the adjuster hand lever 54 is maintained (the adjuster 50 is in the horizontal state) , the adjuster-connecting tube 66 of the

fixture 14 is inserted into the operating hole 38 of the cover 35 of the fixture 12, and the driving connection rod 32 of the fixture 12 is inserted into the connection groove 60 of the adjuster-connecting tube 66. Here, when the user rotates the adjuster hand lever 54 in the clockwise or counterclockwise direction to indicate the "latching" state (the adjuster 50 is in the vertical state), as shown in FIG. 7, the protruding rod 64 of the adjuster-connecting tube 66 is latched on the latching piece 34 installed on the supporting plate 22 of the fixture 12, and the flange portion 62 of the adjuster-connecting tube 66 presses the operating flap 37 of the contact switch 36, thereby causing the second fire door 2b to be latched by the automatic fire door releasing apparatus 10. Under the condition that the protruding rod 64 is latched on the latching piece 34, the closing power of the automatic door closing device 4b, such as a door closer" serves to strengthen the latching of the protruding rod 64 of the latch 14 on the lathing piece 34 of the fixture 12. In the same manner as the second fire door 2b, the first fire door 2a is latched by the automatic fire door release apparatus 10.

When the first and second fire doors 2a and 2b are latched by the automatic fire door release apparatuses 10, the first and second fire doors 2a and 2b maintain their opened states. FIG. 6 illustrates a state, in which the

first and second fire doors 2a and 2b are latched by the automatic fire door release apparatus 10.

In the embodiment as shown in FIGS. 3 to 6, the driving connection rod 32, having a square pillar structure, of the fixture 12 is inserted into the connection groove 60, having a rectangular shape, the adjuster-connecting tube 66 of the latch 14. The above configuration causes a difficulty of correctly aligning the fixture 12 and the latch 14. In order to solve the above problem, in this embodiment, the connection holes 33a and 33b formed through the fixing board 24 have a "+"-shaped section. After the installer installs the fixture 12 and the latch 14, the fixing bolts 31a and 31b inserted into the connection holes 33a and 33b are loosened and the positions of the fixture 12 and the latch 14 are properly moved vertically or horizontally. Then, the fixing bolts 31a and 31b inserted into the connection holes 33a and 33b are screwed again, thereby allowing the connection rod 32 installed on the driving shaft of the reduction motor 30 to be correctly aligned with the connection groove 60 of the adjuster-connecting tube 66.

On the other hand, the structures of the driving connection rod 32 of the fixture 12 and the connection groove 60 of the latch 14, as shown in FIG. 13, facilitate the alignment of the driving connection rod 32 and the connection groove 60.

With reference to FIG. 13, the driving connection rod

32 of the fixture 12 is configured such that an external protrusion 300 is formed on the outer cylindrical circumferential surface of the driving connection rod 32 in a longitudinal direction, and the connection groove 60 of the adjuster-connecting tube 66 of the latch 14 is configured such that an internal protrusion 600 is formed on the inner cylindrical circumferential surface of the connection grove 60 in a longitudinal direction. The driving connection rod 32 having a cylindrical shape is loosely inserted into the connection groove 60 having a cylindrical shape. The external protrusion 300 of the driving connection rod 32 is rotated at most once in the clockwise or counterclockwise direction, thereby contacting the internal protrusion 600 of the connection groove 60. With the structures of the driving connection rod 32 and the connection grove 60 as shown in FIG. 13, only when the driving connection rod 32 is aligned with the connection groove 60, the driving connection rod 32 can be inserted into the connection grove. Further, the connection holes 33a and 33b having a ^λΛ +"-shaped section are formed through the fixing board 24 in FIG. 13, thereby facilitating the adjustment of the driving shaft of the motor.

The automatic fire door release apparatus 10 of this embodiment of the present invention, which achieves the latching operation of the fire doors 2a and 2b, assures power for holding the latching of the fire doors 2a and 2b

regardless of the size or weight of the fire doors 2a and 2b, and does not have to adjust the holding power differently from a solenoid-driven release apparatus, thereby not requiring any additional element for adjusting the holding power. Accordingly, the automatic fire door release apparatus 10 has a simple structure, and rarely malfunctions.

Further, since the automatic fire door release apparatus 10 of the present invention employs a motor-driven method, it is possible to release the latching of the fire doors 2a and 2b from the automatic fire door release apparatus 10 by a user's hand. That is, when a user rotates the adjuster hand lever 54 from the "latching" state to the "releasing" state, the latching of the fire doors 2a and 2b is released, and then the fire doors 2a and 2b in the released state are closed by the closing power of the automatic door closing devices 4a and 4b, such as door closers. The above simple operation for controlling the releasing of the latching of the fire doors by hand solves problems caused by the conventional releasing of the latching of the fire doors.

The releasing of the latching of the fire doors may be achieved by the above-described user' s hand manipulation, or may be achieved by a motor-driven manipulation using an electrical control method by sensing fire, such as smoke or heat, which will be described later.

Hereinafter, the operation of the automatic fire door release apparatus 10 of the present invention by means of the electrical control method will be described in detail.

When the first and second fire doors 2a and 2b are latched by the automatic fire door release apparatus 10, the flange portions 62 of the latches 14 push the operating flaps 37 of the corresponding contact switches 36. Thereby, the first switch portions SWl of the contact switches 36 of the first and second fire doors 2a and 2b are in an "on" state, and the second switch portions SW2 of the contact switches 36 of the first and second fire doors 2a and 2b are in an "off" state.

When a smoke detector installed on the ceiling of an indoor space detects smoke and noxious gas generated due to fire under the above condition, the smoke detector supplies a fire-detecting signal corresponding to the generation of fire to the starting terminal 86 and the common terminal 84 of the contact switch 36 of the first fire door 2a using a starting voltage of 24V. Here, the first switch portion SWl of the first fire door 2a is in the "on" state, thereby forming a closed loop to operate the DC motor 26 of the first fire door 2a.

The driving force of the DC motor 26 of the first fire door 2a is reduced by a predetermined reduction gear ratio through the reduction gear 28, and rotates the driving connection rod 32 of the fixture 12 in the predetermined

clockwise or the counterclockwise direction. Then, the adjuster-connecting tube 66 of the latch 14, into which the driving connection rod 32 is inserted, is rotated together with the rotation of the driving connection rod 32, and the protruding rod 64 of the adjuster-connecting tube 66 is rotated also and separated from the latching piece 34. Simultaneously, the driving connection rod 32 is separated from the connection groove 60 of the adjuster-connecting tube 66 by the closing power of the automatic door closing device 4a. Consequently, the first fire door 2a is closed. When the adjuster-connecting tube 66 of the latch 14 of the first fire door 2a is separated from the fixture 12, the first switch portion SWl of the contact switch 36 of the first fire door 2a is converted into the "off" state, and the second switch portion SW2 of the contact switch 36 of the first fire door 2a is converted into the "on" state. Thereby, starting voltage of 24V is applied to the starting terminal 86 and the common terminal 84 of the contact switch 36 of the second fire door 2b. Then, the DC motor 26 of the second fire door 2b is operated by the above-described procedure the same as that of the operation of the DC motor 26 of the first fire door 2a, and the driving connecting rod 32 of the fixture 12 is rotated by the operation of the DC motor 26. Then, the adjuster-connecting tube 66 of the latch 14, into which the driving connection rod 32 is inserted, is rotated together

with the rotation of the driving connection rod 32, and the protruding rod 64 of the adjuster-connecting tube 66 is also rotated and separated from the latching piece 34. Simultaneously, the driving connection rod 32 is separated from the connection groove 60 of the adjuster-connecting tube 66 by the closing power of the automatic door closing device 4b. Consequently, the second fire door 2b is closed.

When the adjuster-connecting tube 66 of the latch 14 of the second fire door 2b is separated from the fixture 12, the first switch portion SWl of the contact switch 36 of the second fire door 2b is converted into the "off" state, and the second switch portion SW2 of the contact switch 36 of the second fire door 2b is converted into the "on" state. Thereby, the battery power (B ⁺ ) causes current to flow through a closed loop connected to the negative starting voltage (-) through the releasing display lamp 90, the second switch portion SW2 of the second fire door 2b, the common node 84, the second switch portion SW2 of the first fire door 2a, and the common node 84, thereby emitting the releasing display lamp 90.

A supervisor can confirm from the emitting of the releasing display lamp 90 that the releasing of the automatic fire door release apparatus 10 is completely performed. As apparent from the above description, the present invention provides an automatic fire door release apparatus,

which has low production costs and excellent reliability, consumes a minimal amount of current, and releases latching of fire doors by hand. Further, the automatic fire door release apparatus of the present invention assures force for holding the latching of the fire doors regardless of the size or weight of the fire doors, and has a function for preventing re-latching of the fire doors. Particularly, since the consumption amount of current per automatic fire door release apparatus is small, i.e., 20~40mA when loading, when a plurality of the automatic fire door release apparatuses in an apartment having 20 to 30 floors are simultaneously tested or operated, the automatic fire door release apparatuses consume a current of approximately IA. Accordingly, it is possible to solve a cost problem, which is most sensitively considered by fire protection manufactures. Thereby, the automatic fire door release apparatus of the present invention solves a difficulty caused by the use of a storage battery having high costs serving as a preliminary power source. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. For example, the driving shaft of the fixture 12 may be extended to pass

through the supporters 54 and 58 of the latch 14, and the inserting and latching structure between the fixture 12 and the latch 14 may be formed adjacent to the front end of the adjuster 50 of the fixture 14, i.e., the adjuster hand lever 54.

Industrial Applicability

The automatic fire door release apparatus of the present invention is used by a fire protection system, and more particularly, is installed on fire doors at an emergency stair, an emergency elevator, or a region for eliminating smoke in a platform, thereby serving to prevent fire from spreading.