JPH0433080B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fire alarm device that quickly detects smoldering fires while preventing malfunctions.

(Prior art) In recent years, multiple smoke detectors that detect changes in smoke concentration due to the occurrence of a fire in an analog manner are installed in a monitoring area, and a receiver installed in the center receives the analog detection data from these smoke detectors. Research and development is progressing on so-called analog fire alarm devices that determine the presence of a fire by comparing the analog detection data with a preset threshold level.

(Problems to be Solved by the Invention) However, as a result of various experiments, it has been confirmed that the amount of smoke generated and the state of smoke retention differ depending on the fire properties such as ignitability or smolderability.

In other words, in ignition fires caused by the combustion of volatile and highly flammable substances such as gasoline and heptane, upward air currents are generated due to explosive combustion.
Smoke also rises to the ceiling along this rising air current.

On the other hand, in the case of a smoldering fire, the amount of heat generated by the fire is small, so the smoke generated by the fire spreads throughout the room without generating upward air currents. Therefore, the rate of increase in smoke concentration on the ceiling where smoke detectors are installed is slow, and it takes time to reach a predetermined smoke concentration to determine a fire, so it takes time to detect a fire in a smoldering fire. There was a risk of delays.

For this reason, it may be possible to set the threshold level that is the fire level low in accordance with the gradual increase in smoke concentration of smoldering fires, but while it is possible to detect smoldering fires early, it is difficult to detect due to smoke from cigarettes, etc. There was a conflicting problem: it would make it easier to report a fire.

(Means for Solving the Problems) The present invention was developed in view of the above-mentioned problems, and an object of the present invention is to provide a fire alarm device that quickly detects smoldering fires while preventing malfunctions caused by cigarettes, etc. shall be.

In order to achieve this objective, the present invention installs a plurality of analog detection units that detect changes in physical phenomena due to the occurrence of fire in an analog manner within the same monitoring compartment, and detects the detection output from each analog detection unit and the first detection unit. In a fire alarm system that determines a fire by comparing the detection outputs with a threshold value of The sum calculation section is started based on the comparison output from the first comparison section, and the total sum of the detection outputs from each analog detection section calculated in the sum calculation section is compared with a second threshold value set lower than the threshold of . A second comparison section compares the third threshold value set higher than the first threshold value, and a fire is determined based on the comparison output from the second comparison section.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the main part of the present invention, and FIG. 2 is an overall configuration diagram of a fire alarm system constructed by incorporating the embodiment of FIG. 1.

To explain the configuration of the present invention with reference to FIGS. 1 and 2, 1 is a receiver, and signal lines 2 are connected from the receiver 1 to a plurality of monitoring compartments 3a, 3b,...
has been pulled out and connected to multiple fire detectors.
To explain this connection configuration using the monitoring compartment 3a as a representative, there are three fire detectors 4 in the monitoring compartment 3a.
a, 4b and 4c are installed, each with receiver 1
It is connected to signal line 2 from. To explain the internal configuration of the plurality of fire detectors using the fire detector 4a as a representative, the fire detector 4a includes an analog detection section 6a that detects smoke caused by the occurrence of a fire in an analog manner;
It includes a transmission circuit section 5a that transmits analog detection information from the analog detection section 6a. This internal configuration is the same for the other fire detectors 4b and 4c. Further, each of the transmission circuit sections 5a, 5b, 5c built in each of the fire detectors 4a, 4b, 4c has a unique address set in advance, and counts and calculates the calling pulses from the receiver 1. When it is determined that the numerical value matches its own address, analog detection information in the current mode is returned within the idle time that is the pulse interval of the calling pulse.

Next, the internal configuration of the receiver 1 will be explained. Reference numeral 7 denotes a reception processing unit that sends out a call pulse to a plurality of fire detectors and also receives and processes analog detection information returned from each fire detector. This is an arithmetic unit that performs calculations. As shown in FIG. 1, the calculation unit 8 includes an output difference calculation unit 14 that calculates the output difference between the detection outputs of the analog detection units based on the processed data from the reception processing unit 7, and is installed in each monitoring compartment. The total sum calculating section 15 calculates the sum of detection outputs from each analog detecting section. 9 is a fire judgment section, which outputs a signal from the calculation section 8 or receives the signal from the processing section 7;
Determine fire based on processed data from. The internal configuration of the fire determination unit 9 will be specifically explained with reference to FIG. 1. Reference numeral 11 indicates a first threshold value L1 that is the fire level. For example, if the fire alarm is a smoke detector, the smoke concentration is set to 20%. The threshold setting unit 11 includes a comparator 11a for each analog detection unit.
11b and 11c, and the reception processing unit 7
Each time the processed data is obtained, the value of the processed data, that is, the detected output value from the analog detector
is compared with the threshold value L1. Reference numeral 12 denotes an OR circuit, which inputs the comparison outputs from the comparators 11a, 11b, and 11c, and outputs the OR output to the OR circuit 13. 16 is a second threshold value lower than the first threshold L1.
For example, a value of 5% smoke density is set as the second threshold L2. When the first comparison unit 16 obtains the output difference a from the output difference calculation unit 14, it compares the value of the output difference a with a second threshold L2, and determines that the value of the output difference a is equal to or less than the second threshold L2. If so, a signal is output to the sum calculation section 15. Reference numeral 17 denotes a second comparison section, which sets a third threshold L3 higher than the first threshold L1, and compares the sum output from the sum calculation section 15 with the third threshold L3. The value of this third threshold L3 is
For example, it is set to a value as shown in equation (1).

L3=[L1/(Nn)]×N=30[%] N: Total number of analog detection sections n; 1 (1) Here, the value of n is an appropriate value depending on the number of detection sections, which is limited to 1. is set to

Referring again to FIG. 2, reference numeral 10 denotes a display section equipped with display means such as LEDs and lamps, and indicates a fire based on the signal output from the fire determination section 9.

FIG. 3 is an explanatory diagram illustrating the operation of the embodiment of the present invention when a smoldering fire occurs.

The operation will be explained with reference to FIG. First, if a smoldering fire occurs in the monitoring compartment 3a as shown in Figure 2, the smoke generated by the smoldering fire will spread throughout the entire room of the monitoring compartment 3a, causing the fire to be detected. The smoke density value at the ceiling surface where the appliances 4a, 4b, and 4c are installed gradually increases. As shown in FIG. 3, the detection output value from the analog detection section 6a built into the fire detector 4a is A1, the detection output value from the analog detection section 6b built into the fire detector 4b is A3, and the detection output value from the analog detection section 6b built into the fire detector 4c is A1. Assuming that the detection output value from the analog detection section 6c built in is A2, each detection output is received and processed by the reception processing section 7, and the output difference calculation section 14 and the sum calculation section 15 built in the calculation section 8 are processed. given to. The output difference calculation unit 14 calculates the output difference between the detection outputs of the analog detection units, that is, the output difference a between the output values A1 and A2.
1, an output difference a2 between output values A2 and A3, and an output difference a3 between output values A1 and A3, respectively, and output them to the first comparison section 16. The first comparator 16 compares each of the output differences a1, a2, and a3 obtained from the output difference calculation unit 14 with the second threshold L2.
If the values of the output differences a1, a2, and a3 are less than or equal to the second threshold L2, a signal is output to the sum calculation unit 15 to instruct it to start calculation. The sum calculation section 15 starts calculation operation based on the signal output from the first comparison section 16, and calculates the sum of the detection outputs from each analog detection section, that is, the output value A.
1, A2 and A3, ie, A1+A2+A3 is calculated. The second comparison section 17 compares the sum output from the sum calculation section 15 and the third threshold L3, and the sum output from the sum calculation section 15, that is, A1+
If the value of A2+A3 exceeds the third threshold L3, a signal is output to the OR circuit 13. Display section 10
Then, a fire is displayed based on the logical sum output from the logical sum circuit 13.

Next, the operation when a flammable fire occurs due to combustion of a highly flammable substance such as gasoline or heptane will be explained. When a flaming fire occurs, explosive combustion generates an updraft, and smoke rises to the ceiling along this updraft. For example, if the fire detector 4a installed in the monitoring compartment 3a detects a sudden rise in smoke concentration as shown in FIG. The signal is received and processed in the processing section 7 and provided to the calculation section 8 and the fire judgment section 9. In the fire determination section 9, as shown in FIG. 1, the threshold value setting section 11 compares the detection output value from the fire detector 4a with the first threshold value, that is, the fire level L1, and determines whether the value of the detection output value is When the fire level exceeds L1, the signal is immediately applied to the display section 10 via the OR circuits 12 and 13 to display a fire indication.

In the above embodiment, the detection output value from the analog detection section is used as it is to determine a fire, but the rate of change per unit time of the detection value from each analog detection section is calculated, and this A configuration may be adopted in which a fire judgment is made based on the rate of change.

The reception processing unit 7, which will be explained in detail, is provided with a rate of change calculation means, and each time a detection output from each analog detection unit is obtained, the amount of change per unit time is calculated, and the amount of change calculated by this rate of change calculation unit is calculated. Giving the value of the rate of change to the threshold setting unit 11, the output difference calculation unit 14, and the sum calculation unit 15, and setting a threshold L1 that is a predetermined fire judgment level as the first threshold set in the threshold setting unit 11; Also, the first comparison section 1
6 is set to a threshold L2 that is lower than the first threshold L1, and the output difference from the output difference calculation unit 14 is compared with the threshold L2, and if the value of the output difference is less than or equal to the threshold L2. In this step, the sum calculation unit 15 is activated to calculate the sum of the rate of change from each analog detection unit. Furthermore, a value L3 higher than the first threshold L1 is set in the second comparison section 17, and when the value of the sum output from the sum calculation section 15 exceeds the threshold L3, the logical sum circuit A signal may be outputted to the display section 10 via 13 to display a fire message.

In addition, in the embodiment shown in FIG. 1, the output difference calculating section 14 is configured to calculate the output difference between the detection outputs of each analog detecting section, but as shown in FIG. Detected output values A1, A2, A3
If a judgment function is provided to judge between the maximum level A3 and the lowest level A1, and the configuration is configured to calculate only the output difference between the maximum level A3 and the minimum level A1, the calculation processing of the output difference calculation section 14 can be can be reduced. Furthermore, the fire detectors 4a, 4b, and 4c shown in FIG. 2 have been explained using smoke detectors that detect smoke caused by a fire as an example.
It may be configured using a gas detector that detects the concentration of gas such as CO gas generated by a fire in an analog manner, or a temperature sensor that detects a temperature rise due to a fire in an analog manner.

(Effects of the Invention) As described above, according to the present invention, a plurality of analog detection units that detect changes in physical phenomena caused by the occurrence of a fire in an analog manner are installed in the same monitoring compartment, and each analog detection unit In a fire alarm system that determines a fire by comparing the detection output from the analog detector with a first threshold value, the output difference calculation unit calculates the difference in the detection output between the analog detectors, and this output difference is used as the first threshold value.
The sum calculation unit is started based on the comparison output from the first comparison unit, and the calculation is performed in the sum calculation unit. A second comparison section compares the sum of detection outputs from each analog detection section and a third threshold set higher than the first threshold, and a fire judgment is made based on the comparison output from the second comparison section. By doing so, it is possible to quickly and reliably detect not only flammable fires but also smoldering fires, and the reliability of fire alarm systems is greatly improved by preventing non-fire alarms caused by cigarettes, etc. Effects can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the main part of the present invention, Fig. 2 is an overall configuration diagram of a fire alarm system constructed by incorporating the embodiment of Fig. 1, and Fig. 3 is an embodiment of the present invention. It is an explanatory diagram showing operation of an example. 1...Receiver, 2...Signal line, 3a, 3b...
Monitoring compartment room, 4a, 4b, 4c...fire detector,
5a, 5b, 5c...transmission circuit section, 6a, 6b,
6c...analog detection section, 7...reception processing section, 8
...Arithmetic section, 9...Fire judgment section, 10...Display section, 11...Threshold value setting section, 12, 13...Order circuit, 14...Output difference calculation section, 15...Summary calculation section, 16 , 17... Comparison section.

Claims (1)

[Claims] 1. A plurality of analog detection units that detect changes in physical phenomena due to the occurrence of fire in an analog manner are installed in the same monitoring compartment, and the detection output from each analog detection unit and the first threshold value are A fire alarm device that determines a fire by comparing the output difference between the analog detectors and the output difference calculation unit that calculates the difference in detection output between the analog detection units; The second set
a first comparison section that compares the detection outputs with a threshold value; a sum calculation section that is activated based on the signal output from the first comparison section and calculates the sum of detection outputs from each of the analog detection sections; A second comparison section is provided to compare the calculation output from the calculation section and a third threshold set higher than the first threshold, and a fire is determined based on the comparison output from the second comparison section. A fire alarm device characterized by: