BEST MODE FOR CARRYING OUT THE INVENTION

[0032] FIG. 1 is a schematic view showing a structure of a sprinkler in accordance with the preferred embodiment of the present invention and FIG. 2 is a side view of the sprinkler in FIG. 1 . As shown in these drawings, the sprinkler comprises a head H for sensing the ambient temperature and discharging extinguishing liquid in accordance with the sensed result, and a sprinkler head controller C for controlling the operation of the sprinkler and checking the presence of a fault in the sprinkler.

[0033] In FIGS. 1 and 2 , the reference numeral 2 denotes the body of the sprinkler head H, 29 denotes the body of the sprinkler head controller C, 8 and 9 denote conductors for electrically connecting the sprinkler head H to the sprinkler head controller C, 20 and 21 denote conductors for electrically connecting a thermistor 22 (see FIG. 5 ) to the sprinkler head controller C, and 32 denotes a wire duct containing power lines for applying electric power to the sprinkler head H and controller C and signal lines for transmitting and receiving signals to/from other equipment. Also, the reference numeral 33 denotes an extinguishing liquid supply pipe coupled with an extinguishing liquid storage tank (not shown), 23 denotes a pipe coupling socket for coupling the sprinkler head H with the extinguishing liquid supply pipe 33 , and 36 denotes a fixing band for fixing the body 29 of the sprinkler head controller C to the extinguishing liquid supply pipe 33 .

[0034] The sprinkler head H includes, as shown in FIG. 3 , an extinguishing liquid discharging nozzle 1 coupled at the upper end of the body 2 with the extinguishing liquid supply pipe 33 via the pipe coupling socket 23 , and an extinguishing liquid diffusing plate 6 fitted horizontally under and to the lower end of the body 2 , and a negative electrode 9 attached on the outer surface of the body 2 .

[0035] A valve plate 3 is supported by a linked trigger 4 toward the lower end of the extinguishing liquid discharging nozzle 1 to normally hold the discharging nozzle 1 closed. The trigger 4 is made of any proper conductive material and is electrically grounded to keep uneven balance via a thermal fuse F between a binding bolt 5 , which fits the diffusing plate 6 to the body 2 , and the valve plate 3 .

[0036] The thermal fuse F includes, as shown in FIGS. 4 a to 4 c , a hollow drum-shaped, non-conductive casing 11 made of any proper non-conductive material (for example, ceramic) and enclosed at its bottom, low-temperature fusing, conductive element 13 made of any proper conductive material (for example, lead), filled within the casing 11 , held solid at room temperature and easily fusing at a low temperature, and a conical, non-conductive actuating pin 12 made of any proper non-conductive material (for example, ceramic), held within the conductive element 13 at its lower end and projected out of the top of the casing 11 at its upper end

[0037] A negative electrode contact member 10 is attached on the lower end of the non-conductive casing 11 at its one end and connected to the negative electrode 9 at its other end, and a positive electrode 8 is attached on the inner surface of the casing 11 . Helically laid on the outer surface of the non-conductive casing 11 is an electric heater (for example, a carbon paste or metal film) 14 connected to the negative electrode contact member 10 at its one terminal and to the positive electrode 8 via the conductive element 13 at its other terminal. An anticorrosive, insulating film 15 is coated on the outer surface of the electric heater 14 , or the outermost portion from the outer surface of the non-conductive casing 11 , to protect the electric heater 14 .

[0038] FIG. 5 is a circuit diagram of a sprinkler apparatus in accordance with the preferred embodiment of the present invention. As shown in this drawing, the sprinkler apparatus comprises the thermal fuse F, a temperature sensing circuit TS, the sprinkler head controller C and a main computer MC in a central control station.

[0039] The temperature sensing circuit TS is installed in the sprinkler head H to readily sense high heat generated upon the occurrence of a fire in a building. To this end, the temperature sensing circuit TS includes the thermistor 22 having its resistance varying with the ambient temperature, and a temperature sensing capacitor 50 .

[0040] The sprinkler head controller C includes a current supply/feedback circuit C 1 for supplying a predetermined amount of rated current to the thermal fuse F and detecting the amount of current fed from the thermal fuse F back thereto, and a one-chip microcontroller C 2 for controlling the current supply/feedback circuit C 1 to supply the predetermined amount of rated current to the thermal fuse F. The microcontroller C 2 is further adapted to analyze the amount of current detected by the current supply/feedback circuit C 1 and determine the presence of a fault in the thermal fuse F and an aged state thereof in accordance with the analyzed result. The sprinkler head controller C further includes a signal transmitter C 3 for transmitting an output signal from the microcontroller C 2 to the main computer MC in the central control station, a signal receiver C 4 for receiving an output signal from the main computer MC and transferring it to the microcontroller C 2 , and a switch 51 for storing an identification number.

[0041] The current supply/feedback circuit C 1 is provided with a control photocoupler 81 , a switching transistor 49 , a current sensing photocoupler 80 , a current sensing capacitor 44 and a plurality of device protection resistors 46 and 48 .

[0042] The signal transmitter C 3 is provided with a photocoupler 82 , a plurality of device protection resistors 53 , 55 and 56 and a signal transmission line 87 , and the signal receiver C 4 is provided with a pair of voltage-division resistors 57 and 58 , a pair of diodes 59 and 60 for preventing a signal overload and limiting a reverse voltage, and a signal reception line 88 .

[0043] A plurality of bypassing diodes 63 and 65 or 64 and 66 are connected to each of the signal transmission line 87 and signal reception line 88 to prevent signal interferences with the other sprinkler head controllers connected in parallel to the same line. As a result, even though a specific sprinkler head controller is damaged, cut, short-circuited or broken down due to a fire, the other sprinkler head controllers will be maintained in operation without any interference from the specific sprinkler head controller.

[0044] Noticeably, provided that sprinkler head controllers in a large number of sprinklers comprise signal lines to the main computer MC in the central control station, respectively, the wire layout in the building will become complicated and the signal lines will be wasteful in number. In special consideration of this point, according to the present invention, the sprinkler head controllers are connected in parallel to the main computer MC in the central control station via signal lines of a two-phase/four-wire system as shown in FIG. 5 . As a result, the wire layout can be simplified and the signal lines can significantly be reduced in number regardless of the number of sprinklers installed in the building.

[0045] For reference, the reference numerals 61 and 62 in FIG. 5 , not described, denote specific resistances of the signal transmission line 87 and signal reception line 88 , respectively, and 92 denotes a direct current (DC) power source (for example, a battery) for supplying DC power to the sprinkler head controller C and temperature sensing circuit TS.

[0046] The main computer MC is installed in the central control station to remotely control a plurality of sprinkler head controllers C and remotely check states of respective sprinklers. Namely, the main computer MC receives information from the sprinkler head controllers C, such as self-diagnostic results, sensed temperature results and actuated states, and displays the received information on display means (for example, a monitor) contained therein. Further, the main controller MC gives an alarm to an operator in the case of danger. In this manner, the main computer MC informs the operator of states of respective sprinkler heads H and transmits a plurality of control commands to the sprinkler head controllers C according to key operations by the operator or an algorithm contained therein to instruct each of the sprinkler head controllers C to perform a self-diagnostic operation or to compulsorily actuate the associated sprinkler head H.

[0047] Now, a detailed description will be given of the operation of the sprinkler apparatus with the above-mentioned construction in accordance with the preferred embodiment of the present invention with reference to FIGS. 1 to 8 .

[0048] First, a self-diagnostic operation for the thermal fuse F by the sprinkler head controller C will be mentioned.

[0049] In the self-diagnostic operation, the microcontroller C 2 in the sprinkler head controller C applies a pulse width modulation (PWM) signal to a light emitting diode 45 in the control photocoupler 81 for a predetermined period of time. At this time, the PWM signal has a duty factor set to such a value that can supply such a small amount of current as to cause no physical variation in the low-temperature fusing element 13 in the thermal fuse F.

[0050] In response to the PWM signal from the microcontroller C 2 , a phototransistor 47 in the control photocoupler 81 and the switching transistor 49 are sequentially switched to supply a predetermined amount of rated test current to the thermal fuse F. At this time, a voltage corresponding to the amount of current flowing to the thermal fuse F is generated across a resistor 41 connected in parallel to a light emitting diode 42 in the current sensing photocoupler 80 , and the light emitting diode 42 thus generates light of an intensity corresponding to the voltage generated across the resistor 41 . As a result, current of an amount corresponding to the intensity of light generated from the light emitting diode 42 flows between a collector and emitter of a phototransistor 43 in the current sensing photocoupler 80 . Then, the current flowing between the collector and emitter of the phototransistor 43 is charged on the current sensing capacitor 44 . At this time, the microcontroller C 2 detects charging/discharging times of the capacitor 44 through its bidirectional input/output port 72 , determines the amount of current flowing through the thermal fuse F on the basis of the detected charging/discharging times and diagnoses an endurance of the thermal fuse F and the presence of a fault therein in accordance with the determined result. Then, the microcontroller C 2 outputs a control signal based on the diagnosed result to the transmitting photocoupler 82 through its output port 76 , thereby causing the photocoupler 82 to generate a pulse signal and transmit it to the main computer MC in the central control station. In other words, with the lapse of a lengthy period of time from the installation of the thermal fuse F, internal lines of the thermal fuse F or connection lines from the thermal fuse F to the power source 92 may be cut or short-circuited due to corrosion or other factors, resulting in a variation in resistance on a current path of the thermal fuse F consisting of positive electrode 8 low-temperature fusing element 13 heater 14 negative electrode contact member 10 trigger 4 negative electrode 9 . In this case, the amount of current flowing through the thermal fuse F becomes different from the previous one, thereby causing the charging/discharging times of the capacitor 44 to become different from the previous ones. As a result, the microcontroller C 2 can check the state of the thermal fuse F on the basis of the charging/discharging times of the capacitor 44 .

[0051] Next, a description will be given of the operation of the sprinkler head controller C which senses the occurrence of a fire through the temperature sensing circuit TS and thus actuates the sprinkler head H.

[0052] The thermistor 22 in the temperature sensing circuit TS has its resistance varying with the ambient temperature, and charging/discharging times of the capacitor 50 vary with the resistance variation of the thermistor 22 . Namely, a time constant based on a resistance R of the thermistor 22 and a capacitance C of the capacitor 50 vary. At this time, the microcontroller C 2 in the sprinkler head controller C detects the charging/discharging times of the capacitor 50 through its bidirectional input/output port 74 , senses the ambient temperature on the basis of the detected charging/discharging times and determines the occurrence of a fire in accordance with the sensed result. Then, the microcontroller C 2 outputs a control signal based on the determined result to the transmitting photocoupler 82 through its output port 76 , thereby causing the photocoupler 82 to generate a pulse signal and transmit it to the main computer MC in the central control station. In the case where the occurrence of a fire is determined, the microcontroller C 2 applies a PWM signal to the light emitting diode 45 in the control photocoupler 81 . At this time, the PWM signal has a duty factor set to such a value that can supply such a predetermined amount of rated current as to allow the heater 14 in the thermal fuse F to generate high heat sufficient to fuse the conductive element 13 . In response to the PWM signal from the microcontroller C 2 , the phototransistor 47 in the control photocoupler 81 and the switching transistor 49 are sequentially switched to supply the predetermined amount of rated current to the thermal fuse F.

[0053] The current from the switching transistor 49 flows through the current path of the thermal fuse F consisting of positive electrode 8 low-temperature fusing element 13 heater 14 negative electrode contact member 10 trigger 4 negative electrode 9 . At this time, the heater 14 generates electric heat higher than a fusing point of the low-temperature fusing element 13 , and the drum-shaped non-conductive casing 11 and conductive element 13 are simultaneously heated due to the electric heat generated from the heater 14 . As the low-temperature fusing element 13 fuses due to its heating, the overlying conical actuating pin 12 moves downwardly, thereby causing the uneven balance of the trigger 4 to be broken and thus the valve plate 3 to be opened. As a result, extinguishing liquid is supplied from the extinguishing liquid storage tank (not shown) to the discharging nozzle 1 through the supply pipe 33 and then discharged from the discharging nozzle 1 . The extinguishing liquid discharged from the discharging nozzle 1 is reflected and diffused by the diffusing plate 6 and thus sprayed within the building. At the same time, the current path of the thermal fuse F consisting of positive electrode 8 low-temperature fusing element 13 heater 14 negative electrode contact member 10 trigger 4 negative electrode 9 is blocked, thereby allowing no current to flow to the heater 14 .

[0054] Next, a description will be given of a control operation of the sprinkler head controller C and the transfer of signals between the sprinkler head controller C and the main computer MC in the central control station with reference to a flowchart of FIG. 6 . This description will be made centering around the sprinkler head controller C.

[0055] For reference, the sprinkler head controller C and the main computer MC in the central control station transmit and receive signals therebetween on the basis of a communication system which counts the number of synchronous pulses. As shown in FIG. 7 , all data start with a synchronous signal in an interval t 1 and is then converted into a pulse signal with a corresponding number of pulses. Subsequently, the pulse signal is transmitted while being divided into different intervals t 2 and t 3 . Here, the synchronous signal has a pulse width PI narrower than that P 2 of the data signal (i.e., P 1 <P 2 ) so that those signals can be identified by the sprinkler head controller C and the main computer MC in the central control station.

[0056] First, upon receiving the DC power from the DC power source 92 , the sprinkler head controller C is initialized to wait for a command from the main computer MC in the central control station at step S 10 . Then, the sprinkler head controller C determines at step S 20 whether it is called by the main computer MC in the central control station. If the sprinkler head controller C is not called by the main computer MC at step S 20 , then it performs a self-diagnostic operation for the thermal fuse F at step S 30 . At step S 40 , the sprinkler head controller C determines from the self-diagnostic result whether a fault is present in the thermal fuse F. If it is determined at step S 40 that the fault is present in the thermal fuse F, then the sprinkler head controller C reports the fault presence to the main computer MC at step S 50 and then ends the control operation.

[0057] In the case where it is determined at the above step S 40 that no fault is present in the thermal fuse F, the sprinkler head controller C senses a current temperature within a place where the related sprinkler is installed, through the temperature sensing circuit TS at step S 60 and reports the sensed result to the main computer MC in the central control station at step S 55 . Then, the sprinkler head controller C determines at step S 70 whether the sensed current temperature exceeds a predetermined threshold value (for example, about 70 C.). Upon determining at step S 70 that the sensed current temperature exceeds the predetermined threshold value, the sprinkler head controller C recognizes that a fire has occurred and then proceeds to step S 120 of actuating the sprinkler. At this step S 120 , the sprinkler head controller C actuates the sprinkler head H to spray extinguishing liquid.

[0058] On the other hand, in the case where it is determined at the above step S 70 that the sensed current temperature does not exceed the predetermined threshold value, the sprinkler head controller C stores a value of the sensed current temperature in a memory contained therein at step S 80 . Thereafter, the sprinkler head controller C reads a previously stored temperature value from the memory at step S 90 and calculates a difference between the read previous temperature value and the sensed current temperature value at step S 100 . Subsequently, the sprinkler head controller C compares the temperature difference calculated at the above step S 100 with a predetermined threshold value (for example, about 3 C.) at step S 110 . If the calculated temperature difference is not greater than the predetermined threshold value as a result of the comparison, then the sprinkler head controller C returns to the above step S 20 .

[0059] In the case where it is determined at the above step S 110 that the calculated temperature difference is greater than the predetermined threshold value, the sprinkler head controller C recognizes that a fire has occurred and then actuates the sprinkler head H to spray extinguishing liquid at step S 120 . Here, the reason for calculating the difference between the current temperature value and the previous temperature value and comparing the calculated temperature difference with the predetermined threshold value is that the sprinkler is allowed to be actuated when the ambient temperature abruptly varies (for example, up to a deviation of 30 C.) as well as when it reaches the predetermined threshold value (for example, 70 C.). That is, when the ambient temperature abruptly varies, the sprinkler head controller C regards such a situation as the occurrence of a fire (i.e., it estimates the fire occurrence at a low temperature) and thus actuates the sprinkler. Thereafter, at step S 130 , the sprinkler head controller C reports the main computer MC in the central control station that the sprinkler has been actuated and then ends the control operation.

[0060] On the other hand, upon being called by the main computer MC in the central control station at the above step S 20 , the sprinkler head controller C transmits an identification number stored by the switch 51 to the main computer MC to acknowledge the call at step S 140 . Here, the main computer MC in the central control station identifies the acknowledging sprinkler head controller C in response to the identification number therefrom and transmits a command to the acknowledging controller C. Upon receiving the command from the main computer MC in the central control station, the sprinkler head controller C analyzes the received command at step S 150 to determine at step S 160 whether the main computer MC has instructed to perform the self-diagnostic operation for the thermal fuse F. If it is determined at step SI 60 that the main computer MC has instructed to perform the self-diagnostic operation for the thermal fuse F, then the sprinkler head controller C proceeds to the above step S 30 of performing the self-diagnostic operation. However, if it is determined at step S 160 that the main computer MC has not instructed to perform the self-diagnostic operation for the thermal fuse F, then the sprinkler head controller C determines at step S 170 whether the main computer MC has instructed to actuate the sprinkler. Upon determining at step S 170 that the main computer MC has not instructed to actuate the sprinkler, the sprinkler head controller C returns to the above step S 20 . However, in the case where it is determined at step S 170 that the main computer MC has instructed to actuate the sprinkler, the sprinkler head controller C proceeds to the above step S 120 to actuate the sprinkler.

[0061] In the present sprinkler apparatus constructed and operated as mentioned above, a plurality of sprinkler head controllers are connected in parallel to the main computer MC in the central control station via communication lines so that they can be controlled in a centralized manner by the main computer MC. This construction allows the operator in the central control station to readily discover a sprinkler with a fault through the main computer MC. Further, upon receiving a report from a certain one of the sprinkler head controllers on the occurrence of a fire, the operator controls others installed in places adjacent to the reporting sprinkler head controller to actuate sprinklers in those places. Therefore, the present sprinkler apparatus can prevent the fire from being spread and thus effectively fight the fire.

[0062] Industrial Applicability

[0063] As apparent from the above description, according to the present invention, sprinkler head controllers provided in sprinklers installed in respective places sense temperatures through temperature sensing circuits and actuate the associated sprinklers in accordance with the sensed results, respectively. Therefore, the present sprinkler apparatus can not only minimize faulty operations of the sprinklers, but also estimate the occurrence of a fire at the initial stage prior to the spreading of the fire and spray extinguishing liquid.

[0064] Further, according to the present invention, sprinkler head controllers provided in sprinklers installed in respective places check the presence of faults in the associated sprinklers by themselves and report the checked results to a main computer in a central control station, respectively. Therefore, an operator in the central control station can readily discover a sprinkler with a fault through the main computer.

[0065] Further, according to the present invention, a main computer in a central control station receives reports from sprinkler head controllers on actuated states of associated sprinklers installed in respective places and instructs the sprinkler head controllers to actuate the associated sprinklers on the basis of the received reports. Accordingly, upon receiving a report from a certain one of the sprinkler head controllers on the occurrence of a fire, an operator in a central control station can control others installed in places adjacent to the reporting sprinkler head controller to actuate sprinklers in those places. Therefore, the present sprinkler apparatus can prevent the fire from being spread and thus effectively fight the fire in complex buildings such as edifices.

[0066] Further, according to the present invention, a plurality of sprinkler head controllers are connected in parallel to a main computer in a central control station via signal lines of a two-phase/four-wire system. Therefore, the wire layout can be simplified and the signal lines can significantly be reduced in number regardless of the number of sprinklers installed in a building.

[0067] 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.