JP2582843B2 - Fire alarm - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fire alarm device that determines that a fire has occurred when the degree of change in heat exceeds a predetermined level.

[Background Art] For example, Japanese Utility Model Publication No. 59-28333 and Japanese Utility Model Publication No. 58-4
According to 4465, the degree of temperature change, that is, the rate of temperature change is monitored, and when the temperature change rate reaches a certain rate of increase, or continues at a rate of increase above a certain value for a certain time or more, the receiver is notified. The figure shows a so-called differential fire detector configured to output a fire signal, which is constituted by an electric circuit.

In such conventional differential fire detectors, a constant temperature rise rate for fire discrimination, or a constant time during which the constant temperature rise rate is to be continued, is always constant regardless of the ambient temperature around the heat detection unit. It is set constant. For this reason, when heating is performed in a state in which the room temperature has dropped to, for example, about 0 ° C. in winter, the temperature of the sensor set on the ceiling rapidly rises and exceeds the set temperature rise rate. There is a drawback that the set time elapses and a malfunction occurs. Conversely, in an environment such as a boiler room where there is always a temperature of 40 to 50 ° C., even if a fire occurs, it is difficult to obtain a predetermined rise rate and a lapse of a certain period of time. There are drawbacks. In such a high temperature environment, the differential heat sensor cannot be used,
Instead, a constant temperature heat detector had to be installed.

[Problems to be Solved by the Invention] As described above, the conventional differential fire detector has a problem that when the ambient temperature is low, it is likely to malfunction, and when it is high, a late report or a false report is likely to occur. Was.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and the temperature rise rate in the current environmental condition is the operating temperature rise rate (that is, the temperature rise rate which is a reference for fire determination). Rate), a differential fire alarm system that determines that a fire has occurred when the operating temperature rise rate, which is the reference for fire determination, is changed according to the environmental temperature.
An object of the present invention is to solve the drawbacks of a conventional differential fire alarm such as a differential heat detector. The characteristic of the operating temperature rise rate with respect to the environmental temperature is set to be large when the environmental temperature is low, and to be small when the environmental temperature is high. If the temperature rise rate exceeds the threshold, it is determined that a fire has occurred.

More specifically, according to the present invention, in a differential fire alarm device that determines a fire based on a temperature rise rate, a first means for determining a current temperature rise rate from a plurality of detection levels representing environmental temperatures; A second means for determining an operating temperature rise rate as a fire determination criterion for each temperature, wherein a characteristic of the operating temperature rise rate with respect to the environmental temperature is large when the environmental temperature is low and high when the environmental temperature is high. The second means, which is sometimes set to be small, is provided.

According to another aspect of the present invention, an upper limit value and a lower limit value are set for the characteristic of the operating temperature rise rate.

Embodiment An embodiment of the present invention will be described below with reference to the drawings, taking the case of a differential heat sensor as an example.

FIG. 1 is a block circuit diagram showing an example of a fire alarm apparatus to which an embodiment of the present invention is applied. In the figure, RE is a receiver, DE _{11 to} DE _1n ... DE _{n1 to} DE _nn are a fire detector which is connected by the receiver RE and for each pair a power supply and traffic L ₁ ~L _n. Note that only the inside of the fire detector DE ₁₁ is shown in detail, but the same applies to other fire detectors.

In the fire detector DE ₁₁ , the MPU is a microprocessor, and the ROM 1 is a program storage area in a main memory associated with the microprocessor MPU, and fixedly stores a program described later with reference to the flowchart of FIG.

ROM2 fixedly stores a table of an operating temperature rise rate with respect to an environmental temperature. An area for storing a temperature versus an operation rise rate table in a main memory. RAM1 rewrites N detection output levels, that is, sensor output levels as needed. RAM2 is a work area in the main memory, FS is a fire development detection unit that detects a physical quantity related to fire, and in this embodiment, It is a thermal detector.

TH is a thermistor as an example of a heat-sensitive element, AD is an analog-to-digital converter, TX is a fire signal transmission unit (in the case of the polling method, it becomes a transmission and reception unit), IF1 and IF2 are interfaces, It is.

The operation of FIG. 1 will be described with reference to the flowchart of FIG.

Following the initial setting (step 201), the fire phenomenon detector F
Detection output level converted from S to digital signal by analog-to-digital converter AD, that is, sensor output level
The SLV is read into the work area RAM2 via the interface IF1 every few seconds, for example, every two seconds (step 20).
2), read filled-in sensor output level to the RAM2 is then written to the sensor output level storage area RAM1 as the current sensor output level SLV _n, this time the oldest data is discarded (step 203).

The sensor output level storage area RAM1 is shown in FIG. 3, and the storage location of n data (that is, the sensor output level) is shown. The latest data, that is, the sensor output level SLV _n is stored at the top of the storage area, the data stored up to that point is sequentially shifted down one by one, and the last, ie, the lowest data in the SLV _n - _n is discarded. In this way, the sensor output level storage area RAM1 always stores the latest n data.

When the latest sensor output level SLV is stored at the top of the sensor output level storage area RAM1, next, based on the sensor output level stored in the sensor output level storage area RAM1 Calculation of the temperature rise rate DT is performed (step 204). There are various methods for calculating the temperature rise rate DT, and for example, the following method can be used.

First, consider a method of determining a gradient with respect to time between the sensor stored in Sansa output level SLVn and lowest location stored in the location of the top-level output level SLV _n in RAM 1 _(n-1) And is determined by Equation 1 below.

(Here, α is a sampling interval.) The gradient determined by this (Equation 1), that is, the temperature rise rate DT is conceptually shown in FIG.

Secondly, a method is also conceivable in which the gradient of each adjacent sensor output level stored in the RAM 1 is calculated as an average value over the whole, and is determined by the following equation (2).

The gradient determined by this equation 2, that is, the temperature rise rate
The DT is shown conceptually in FIG.

In addition to the above, various methods such as a method using the least squares method are conceivable. In the present invention, any of them can be used as a method for determining the temperature rise rate.

Returning to FIG. 2, step 204 shows an example in which the above equation 1 is used as a method for obtaining the temperature rise rate DT. Note that the decimal point generated by the division of Equation 1 is rounded down.

When the temperature rise rate DT is obtained in step 204, the oldest sensor output level SLV _n− ( _n−1 ) stored in the predetermined sensor output level storage RAM 1 is set as the environmental temperature Ti. , The operating temperature rise rate dT corresponding to the environmental temperature Ti
i is read from the temperature-operation increase rate table storage area ROM2 (step 205). Note that this step 205 shows a case where the oldest sensor output level in the RAM1, that is, the last memory location in the RAM1, is specified as the environmental temperature Ti, and the data in the specified location is extracted as environmental information. However, the specific memory location for extracting the environment information Ti is not limited to the last memory location, but may be any memory location in the RAM 1.

The contents of ROM2 are shown in FIG.
_n- ( _n-1 ), that is, one storage location is provided corresponding to Ti, and each storage location has an operating temperature rise rate dTi
Is stored. The relationship between the environmental temperature Ti and the operating temperature rise rate dTi is, as an example, conceptually shown in the graph of FIG.
i is such that it is suitable for performing fire monitoring. Although not shown in FIG. 5, it is more preferable to set an upper limit and a lower limit for the operating temperature rise rate dTi with respect to the environmental temperature Ti.

The simplest method for obtaining the optimum characteristic curve as shown in FIG. 5 is obtained by a linear function. For example, if a reference temperature A, an operating temperature rise rate B corresponding to the temperature, and a slope Kc (where Kc ≦ 0) are given, the operating temperature rise rate dTi at an arbitrary environmental temperature Ti is given by the following equation. Is required.

dTi = Kc · Ti + B−Kc · A (Equation 3) Furthermore, the upper limit value H and the lower limit value L of the operating temperature rise rate dTi.
Is set, and if dTi exceeds these ranges, it is fixed to H or L.

A = 20 ° C., B = 8 ° C./min, Kc = −0.5, H = 25 ° C. /
If L = 5 ° C./min, the relationship between the environmental temperature Ti and the operating temperature rise rate dTi is as shown in FIG.

The operating temperature rise rate can also be obtained by a hyperbolic function.
For example, if a temperature A serving as a reference, an operating temperature rise rate B corresponding to the temperature A, a minimum use temperature C, and a coefficient Ks (preferably 0 ≦ Ks ≦ 10) for controlling the slope of the curve are given, an arbitrary environment can be obtained. The operating temperature rise rate dTi at the temperature Ti is obtained by the following equation.

dTi + {D / (Ti−A)} ^Ks (Equation 4) (However, D = (AC) · B ^{(1 / Ks)} ) Further, the upper limit value H and the lower limit value L of the operating temperature rise rate are set. If dTi exceeds these ranges, H or L is fixed.

A = 20 ° C., B = 8 ° C./min, C = −30 ° C., Ks = 1.2, H
= 25 ° C./min and L = 5 ° C./min, the relationship between the environmental temperature Ti and the operating temperature rise rate dTi is as shown in FIG.

Note that the relationship between the environmental temperature to be stored in the table storage ROM 2 and the operating temperature rise rate is not limited to those shown in FIGS. 8 and 9;
Various other things are considered such that dTi is large and dTi is small when Ti is high, and it is also possible to use some of these relationships in combination as appropriate. For example, the characteristics of dTi are set to two different gradients at the middle inflection point.
It can also be a characteristic consisting of two curves.

Further, in the present embodiment, the characteristics shown in FIG. 8 or FIG. 9 are stored in advance in the ROM 2 for storing the temperature versus operation rise rate table, and the operation temperature rise rate dTi corresponding to the environmental temperature Ti is stored. , But an expression such as Expression 3 or Expression 4 is stored as a subprogram,
Of course, the operating temperature rise rate dTi can be directly obtained by calculation from the environmental temperature Ti.

In step 205, when the operating temperature rise rate dTi corresponding to the environmental temperature Ti is read from the temperature vs. operation rise rate table storage area ROM2, the current temperature rise rate DT calculated in step 204 is then replaced by a reference value. And the operating temperature rise rate dTi. If the temperature rise rate DT is smaller than the operating temperature rise rate dTi (N in step 206), the process returns to step 202, reads the next sensor output level SLV _n at the next sampling time, and continues the operation from step 203 similarly. Can be If the temperature rise rate DT is equal to or higher than the operating temperature rise rate dTi,
(Y in step 206), the fire signal transmission unit TX is operated via the interface IF2, and a fire signal is transmitted to the receiver RE (step 207). At this time, the fire signal transmission unit TX
The self address may be transmitted together with the fire signal, or only the self address may be transmitted.

A fire signal from the fire detector is received by the receiver RE, the receiver RE is judged whether it has received the fire signal (or address signal) from any of the line L ₁ ~L _n, and occurrence of fire Display fire alarm area. If the fire detector also sends out its own address along with the fire signal, the receiver identifies and displays the location of the fire or the number of the fire detector that sent the address signal from the received address signal. I do.

In the above embodiment, the case where the present invention is applied to a fire alarm device in which a fire detector performs a fire determination and transmits a fire signal and / or an address signal to a receiver has been described. Is an analog fire alarm that sends a physical quantity signal of the detected fire phenomenon, and performs a fire discrimination based on the physical quantity signal sent from the analog fire sensor with a receiver or a relay device, so-called analog fire alarm The present invention can be applied to an apparatus.

Thus, when applying the present invention to a fire warning device that performs fire determination by the receiver or repeater, a fire detector DE ₁₁ ~DE _nn is the analog thermal fire detector in Figure 1 (heat In each of the thermal fire sensors, the ROM 2 for storing the temperature / operation rise rate table and the RAM 1 for storing the sensor output level are omitted, and the fire signal transmission unit TX transmits and receives signals to and from the receiver RE. Transmitter / receiver unit (having a parallel / serial converter, transmission circuit, serial / parallel converter, receiving circuit, etc.)
Is changed to Then, in the program storage ROM 1, not the program shown in the flowchart in FIG.
When a call is received by polling from the receiver RE, a program for transmitting data of the detection output level of the fire event detection unit FS to the receiver RE via the transmission / reception unit TX is stored.

On the other hand, the receiver RE or the repeater includes a microprocessor MPU in the fire detector DE ₁₁ shown in FIG. 1, a ROM 1 for storing a program, a ROM 2 for storing a table of temperature-operation increase rate,
Sensor output level storage RAM1, work RAM2, transceiver TX
And a display unit. And RO for program storage
M1 sequentially polls a plurality of connected fire sensors, and outputs the sensor output level SL from the polled fire sensors.
Each time a V is received and a sensor output level SLV is received, a fire determination is performed for each fire sensor in the same flowchart as in FIG. 2, and a program for displaying the result on a display unit or the like is stored. Also, RA for sensor output level storage
M1 is provided with a storage area capable of storing n sensor output levels for each of a plurality of connected fire sensors.

[Effects of the Invention] As described above, according to the present invention, when the temperature rise rate in the current environmental state exceeds the operating temperature rise rate that is a fire determination criterion, it is determined that a fire has occurred. In the fire alarm system, the operating temperature rise rate, which is the reference for fire discrimination, is changed according to the environmental temperature.
This has the effect of minimizing the possibility of false alarms when the environmental temperature is low and unreporting when the environmental temperature is high.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a fire alarm device according to one embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of a program stored in a program storage area ROM1 of FIG. FIG. 3 is a diagram showing details of a sensor output level storage area RAM1 of FIG. 1, FIG. 4 is a view showing details of a temperature vs. operation increase rate table storage area ROM2 of FIG. 1, and FIG. Storage area RO for temperature vs. operation rise rate table
FIGS. 6 and 7 are graphs showing the relationship between the environmental temperature Ti and the operating temperature increase rate dTi stored in M2, and FIGS. 6 and 7 each illustrate an example of how to determine the temperature increase rate DT at the current environmental temperature. 8 and 9 are diagrams showing examples of characteristics of the operating temperature rise rate dTi with respect to the environmental temperature Ti. In the figure, RE is a receiver, DE _{11 to} DE _nn are fire detectors, MPU is a microprocessor, FS is a fire detector, R
OM1 is an area for storing a program, ROM2 is an area for storing a temperature vs. operation increase rate table, RAM1 is an area for storing a sensor output level, RAM2 is a working area, and TX is a fire signal transmitting unit.

Claims (3)

(57) [Claims] 1. A differential fire alarm system for distinguishing a fire based on a temperature rise rate, a first means for determining a current temperature rise rate from a plurality of detection levels representing an environmental temperature; A second means for determining an operating temperature rise rate as a criterion, wherein a characteristic of the operating temperature rise rate with respect to the environmental temperature is large when the environmental temperature is low and small when the environmental temperature is high. A fire alarm device, comprising: the second means set in (1). 2. The fire alarm device according to claim 1, wherein an upper limit value and a lower limit value are set for the characteristic of the operating temperature rise rate. 3. The apparatus according to claim 2, further comprising: third means for storing and updating a plurality of detection levels representing the environmental temperature, wherein the operating temperature rise rate is one of the plurality of detection levels stored in the third means. 3. The fire alarm device according to claim 1, wherein the fire alarm device is determined by an environmental temperature represented by a detection level of: