JP2635239B2 - Fire alarm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire alarm system for detecting a temperature, smoke density, and the like due to a fire with an analog sensor and judging a fire at a receiver.

[0002]

2. Description of the Related Art In recent years, in order to solve the problem of false alarm and delay in fire detection in a so-called on / off type fire alarm system in which a fire detector is provided with a threshold value to make a fire judgment, the temperature or smoke density due to a fire has been increased. Is detected by an analog sensor and sent to a receiver, and a so-called analog fire alarm device that determines a fire based on analog data received by the receiver has been proposed.

[0003]

In such an analog fire alarm device, the reliability of the analog data is extremely important because the fire is determined by processing the analog data from the sensor. If the sensor installation conditions, that is, the height of the ceiling surface where the sensors are installed are changed even if the property is obtained, it is expected that the analog data will be different even under the same fire condition. However, in the conventional device, the height of the ceiling surface on which the sensors are installed is not taken into consideration, and there is a problem in the reliability of fire determination when a plurality of analog sensors are installed on ceiling surfaces having different heights.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. Even if the installation height of an analog sensor for detecting a change in physical phenomena due to a fire is different, An object of the present invention is to provide a highly reliable fire alarm device that can perform a fire judgment process without being affected by the installation height.

In order to achieve this object, the present inventors have experimentally considered the correlation with the height of the analog detection signal when the height of the ceiling surface on which the analog fire sensor is installed is changed, and judge the fire. The alarm level threshold, which is the reference of the above, is corrected based on the correlation, and the presence or absence of a fire is determined by comparing the corrected alarm level threshold with the analog detection signal output from the analog sensor. I made it.

Further, a value of a future danger is calculated based on a change tendency of an analog detection signal from an analog fire sensor obtained from the past to the present, and a danger threshold which is a criterion of fire occurrence is set to the above-mentioned value. Correction calculation processing is performed based on the height of the installation position of the analog sensor, and the presence or absence of a fire is determined by comparing the risk threshold value obtained in the correction calculation processing with the value of the risk.

[0007]

According to such a configuration, an alarm level threshold or a danger threshold set in advance as a criterion for judging the occurrence of a fire is corrected in accordance with the installation height of the analog sensor, and is output from the analog sensor. The presence or absence of a fire is determined by comparing the direct analog detection signal with the corrected alarm level threshold, or comparing the value of the risk determined based on the detection signal output from the analog sensor with the corrected risk threshold. Since the judgment is made, it is possible to always make a fire judgment under constant monitoring conditions by compensating for the change in detection sensitivity caused by the difference in the installation height of the analog sensor, and to improve the accuracy of the fire judgment. Can be.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First, a fire alarm device that determines the occurrence of a fire from the degree of danger will be described. The configuration will be described with reference to FIG.
1b... 1n are analog sensors for detecting and outputting changes in physical phenomena due to fire, for example, temperature or smoke density in an analog manner, and analog detection signals output from the analog sensors 1a to 1n are transmitted to the receiver 2. Is supplied via wire. The analog detection signals from the analog sensors 1a to 1n may be sent out in response to a time-division call from the receiver 2.

A sampling circuit 3 is provided in the receiver 2 to which the analog sensors 1a to 1n are connected by signal lines. The sampling circuits 3 sample the analog detection signals of the analog sensors 1a to 1n at regular intervals, and the A / D converter 4 The signal is converted into a digital signal.
Supplied to The fire judging circuit 6 calculates a change tendency (such as a rise in temperature or smoke density) of the detection signal obtained within a predetermined period of time going up from the present time to the past, and predicts a degree of danger in the near future from this tendency. By comparing the degree of risk with a threshold value of risk set as a criterion set internally in advance, a function of quickly determining the occurrence of a fire is provided.

[0010] Here, the danger is defined as a rise in temperature or smoke density due to the occurrence of a fire, and a time required until the environmental state for humans reaches a dangerous state (danger level) in the near future. For example, as a process for obtaining the risk level, a time required to reach a predetermined risk level is predicted based on a difference between a detection signal obtained by sampling at the current time and a detection signal obtained by the previous sampling. Calculate the difference method, or approximate the change in temperature or smoke concentration due to fire with a polynomial, calculate the polynomial constant from multiple detection signals obtained now and in the past, and reach a predetermined dangerous level A function approximation method that finds the time as a solution of a polynomial is applied. Then, the risk calculated by such a difference method or the function approximation method is compared with a predetermined risk threshold, and when the risk is smaller than the risk threshold, it is determined that a fire has occurred. That is, the risk corresponds to the time from the present time to the near future when it is determined that a fire has occurred. Therefore, the smaller the value of the risk is, the higher the possibility of a fire is occurring. If the value is smaller than the threshold value, it is determined that a fire has occurred.

Then, as the fire judging circuit 6 judges that a fire has occurred, the alarm display unit 7 responds by displaying on an internal display or sounding an alarm bell. An installation height setting circuit 8 sets the installation height of each of the analog sensors 1a to 1n in advance. Reference numeral 9 denotes a threshold value correction circuit which corrects the risk threshold value set in the fire determination circuit 7 in accordance with the installation height of each of the analog sensors 1a to 1n set in the installation height setting circuit 8. The fire determining circuit 6 compares the corrected risk threshold with the above-described risk to determine whether a fire has occurred.

The correction of the risk threshold by the correction calculation circuit 9 is performed by changing the correlation between the detection signal output of the analog sensor and the change of the detection signal output when the height of the ceiling surface is changed (see FIGS. 2 and 3). (Shown) is experimentally obtained and performed based on this correlation. That is, FIG.
The level of the detection signal when the smoke sensor is installed at a height of 5 m is set to y = 1.0, and the change based on the experimental data of the relative value of the level of the detection signal when the height of the smoke sensor is changed is shown. Fig. 3 shows the temperature sensor at 2.5m just above the fire point.
, The level of the detection signal when y is set to y = 1.0,
2 shows a change based on experimental data of the relative value of the level of the detection signal when the height of the ceiling surface is changed. The relational expression between the relative value y and the height H of the ceiling surface is shown in FIGS. In each case,

[0013]

(Equation 1)

It can be experimentally confirmed that approximation can be made by
Where α is a coefficient to correct the variation of the sensor output,
Is a reference height of 2.5 m, and β is a predetermined index value. Furthermore,
When the relational expression of the risk threshold value R with respect to the installation height H of the sensor is obtained from the relationship of the above expression (1), the risk threshold value set in advance when the installation height is 2.5 m (reference height) To R
o, that is, the risk threshold when the relative value is y = 1.0 is Ro
If you have the relationship

[0015]

(Equation 2)

Is obtained, and a correlation as shown in FIG. 4 is obtained. The validity of the correlation shown in the above equation 2 and FIG. 4 is apparent from the fact obtained empirically. That is, as described above, the degree of danger is equivalent to the time from the present time until a fire is determined in the near future, and the higher the height of the ceiling where the analog sensor is installed, the slower the rise in the indoor temperature. Also, from the fact that the smoke density rises slowly, it is necessary to increase the danger threshold value as the sensor installation position becomes higher, and to detect the fire quickly, and the above equation 2
The correction based on the correlation between FIG. 4 and FIG. 4 is extremely appropriate.

The threshold correction circuit 9 shown in FIG. 1 corrects and calculates the threshold value of the risk based on the above equation (2) when the fire determination circuit 6 determines the fire by calculating the risk. The fire judging circuit 6 judges the presence or absence of a fire by comparing the danger level corrected by the threshold value correction circuit 9 with the danger level. Next, the operation of the embodiment of FIG. 1 will be described according to the operation flow of FIG.

First, in block a, a correction operation of the threshold value of the risk is executed from the height H of the ceiling surface set for each analog sensor based on the equation (2). , Rn
Set. Subsequently, in block c, analog data is sampled to obtain detection data D1, D2,.
The risk R was calculated by the difference method or the threshold number approximation method from a plurality of pieces of detection data obtained now and in the past in the block d, and the corrected risk threshold of each sanse calculated in the block b was calculated. The risk is compared, and if the calculated risk is equal to or less than the corrected threshold number of risk, block f
Will give a fire alarm.

Next, a fire alarm device for judging the presence or absence of a fire by comparing a detection signal output from the analog sensor with an alarm level threshold value and correcting the alarm level threshold value according to the installation height of the analog sensor. An example will be described. The configuration of the apparatus is the same as that of FIG. 1. The alarm level threshold So set in advance in the fire judgment circuit 6 in FIG.
The correction is performed based on the data of the installation height of the analog sensor set in (1).

That is, also in this embodiment, FIGS.
The correlation of the alarm level threshold value S with respect to the sensor installation height H is obtained from the relationship of the above equation (1) corresponding to the above equation, and the alarm level threshold value is corrected based on this correlation. When the installation height of the analog sensor is 2.5 m (reference height), the preset alarm level threshold value is So, that is, the relative value is y.
Assuming that the alarm level threshold when So = 1.0 is So,

[0021]

(Equation 3)

Is obtained, and the correlation is as shown in FIG. The validity of the correlation shown in the above equation 3 and FIG. 5 is apparent from the fact obtained empirically. That is, the level of a detection signal output from an analog sensor such as a temperature sensor or a smoke sensor becomes higher as the height of the ceiling where these analog sensors are installed is lower, and conversely, as the height of the ceiling is higher, the temperature and smoke are higher. Because it spreads, it gets lower. Then, as the ceiling becomes higher, the detection signal level with respect to the alarm level threshold becomes relatively lower, so that the fire judgment is delayed. Therefore, it is necessary to quickly make a fire determination by lowering the alarm level threshold as the ceiling becomes higher, and thus the correlation shown in FIG. 5 has validity in an actual case.

The operation of the embodiment based on this correction is also shown in FIG.
Are performed in the same manner as in the flowchart shown in FIG.
As described above, according to these embodiments in which the correction processing is performed based on the above formulas (2) and (3), the height H of the ceiling surface is divided into several stages, and the risk threshold value, By enabling the setting of the alarm level threshold value, the setting is easy, and an effect is obtained that even if the height of the ceiling surface is slightly changed, the setting is not changed each time.

In the embodiment described above, the approximate expressions (2) and (2) are obtained based on the experimentally obtained correlations shown in FIGS.
The case where (3) is obtained and various threshold values are corrected in accordance with the equations (2) and (3) has been described. However, correction based on theoretical analysis, not based on such experimental results, will be further described. I do. That is, the relative output y in the equations (2) and (3) is theoretically obtained.

FIG. 7 is an explanatory diagram of a smoke diffusion model schematically showing the state of diffusion of smoke from the fire point F, showing a state in which smoke is diffused from the fire point F in a conical shape. Here, the reference height at which the analog sensor is installed to obtain the relative output y 'is Ho, the installation height of the analog sensor having the changed height is H, and the diffusion areas at the heights H _O and H are So and S. In this case, the output of the analog sensor has a relationship inversely proportional to the diffusion area.

Therefore, the installation height H with respect to the reference height Ho
The relative output y 'of the analog sensor is

[0027]

(Equation 4)

Given by Here, α is a coefficient for correcting variation in sensor output. Then, taking out the conical section of FIG. 7 to obtain the diffusion areas So, S in the above equation (4), it becomes as shown in FIG.

[0029]

(Equation 5)

[0030]

(Equation 6)

## EQU1 ## Here, tan θ is a coefficient obtained from an experimental value. Equations (5) and (6) are converted to the equation (4).
Substituting into the expression,

[0032]

(Equation 7)

Is obtained. Therefore, if the installation height H of the analog sensor is known, the relative output y 'to the reference height Ho is obtained.
Is calculated, and correction calculation of the detection data or the threshold value can be performed in the same manner as in the above-described embodiment. Note that the fire point F, which is the vertex of the cone, is an ideal point, and is not actually the fire point F, but has a predetermined area S ', and thus the reference height Ho is lower than the floor.

FIG. 9 is a graph showing the relationship between the sensor output and the height for obtaining another relative output used to execute the correction operation of the present invention. That is, FIG. 9 shows experimental data of the sensor output x when the installation height H of the analog sensor is changed. Even if the detection structure is the same, the characteristics vary for each sensor as shown in FIG. As shown in the figure, even if the sensor is the same, the characteristics vary depending on the kind of the combustion material, and the sensor output at the height H = 0 m has different values. However, if the height coordinate axis is extended like an imaginary line and the curve is obtained mathematically, it is understood that the sensor output becomes infinite when shifted by a constant a.

Therefore, the characteristic shown in FIG.

[0036]

(Equation 8)

Can be expressed as follows. From this relational expression, the sensor output xo at the reference height Ho is

[0038]

(Equation 9)

And the sensor output x at the height H
Is

[0040]

(Equation 10)

## EQU1 ## Therefore, the relative output y is

[0042]

[Equation 11]

From the relation of the relative output, the detection data or the threshold can be corrected in the same manner as in the above-described embodiment. In this way, an equation for correction similar to that obtained experimentally can be obtained by a theoretical model, and the present invention can realize extremely reasonable and highly reliable fire notification.

In the embodiment shown in FIG. 1, the correction calculation of the detected data is performed on the receiver side.
1 to 1n may be provided with a correction operation circuit, and data corrected based on the height of the ceiling surface may be output to the receiver 2.

[0045]

As described above, according to the present invention, an alarm level threshold or a risk threshold set in advance as a criterion for judging the occurrence of a fire is corrected in accordance with the installation height of the analog sensor. A direct analog detection signal output from the analog sensor is compared with the corrected alarm level threshold, or a risk value obtained based on the detection signal output from the analog sensor is compared with the corrected risk threshold. This makes it possible to judge the presence or absence of a fire, thereby compensating for the change in detection sensitivity caused by the difference in the installation height of the analog sensor, making it possible to always make a fire judgment under constant monitoring conditions. Accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing a relative change of a smoke sensor output with respect to a height of a ceiling surface.

FIG. 3 is a graph showing a relative change of a temperature sensor output with respect to a height of a ceiling surface.

FIG. 4 is a graph illustrating a principle of correcting a risk threshold.

FIG. 5 is a graph for explaining the principle of correcting the alarm level threshold.

FIG. 6 is a flowchart illustrating a processing operation of the embodiment.

FIG. 7 is an explanatory diagram of a smoke diffusion model assumed for obtaining another correction coefficient.

FIG. 8 is a sectional view of a diffusion model used for obtaining a diffusion area of the diffusion model.

FIG. 9 is a graph showing a relationship between a sensor output and a height for obtaining another correction coefficient.

[Explanation of symbols]

 1a to 1n; Analog sensor 2; Receiver 3: Sampling circuit 4: A / D converter 5; Correction operation circuit 6; Fire judgment circuit 7; Alarm display section 8;

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokuo Muroi 1-8-3, Akatsukashinmachi, Itabashi-ku, Tokyo (72) Inventor Hiromasa Ishii 405, Hanamigawa 1-405, 405, 72, Inami Takashi Ono, Inventor Takashi Ono 564 Takada-cho, Kohoku-ku, Yokohama-shi, Kanagawa 5

Claims (2)

(57) [Claims] An analog sensor for detecting a change in a physical phenomenon of the surrounding environment due to the occurrence of a fire in an analog manner and outputting the analog detection signal, and setting a height (H) of an installation position of the analog sensor. Installation height setting section and analog sensor detection when the ceiling height is changed
The change of the signal is detected by a detection signal at a predetermined reference height (Ho).
It is determined in advance as a characteristic of a relative value (y) of 1.0,
From the characteristics of the relative value of the output signal, the height (H) of the installation position
The relative value (y) of the detection signal at
Based on the alarm level threshold value (S) of the reference height (Ho).
o) to correct the threshold (S) at the installation height (H).
A threshold correction unit for calculating a threshold value, a fire determination unit for performing a fire determination process of comparing the alarm level threshold (S) corrected by the threshold correction unit with an analog detection signal output from the analog sensor, A fire alarm device, comprising: an alarm display unit for displaying an alarm by a fire output. 2. An analog sensor for detecting a change in a physical phenomenon of the surrounding environment due to the occurrence of a fire in an analog manner and outputting the analog detection signal, and setting a height (H) of an installation position of the analog sensor. Installation height setting section and analog sensor detection when the ceiling height is changed
The change of the signal is detected by a detection signal at a predetermined reference height (Ho).
It is determined in advance as a characteristic of a relative value (y) of 1.0,
From the characteristics of the relative value of the output signal, the height (H) of the installation position
The relative value (y) of the detection signal at
Based on the reference height (Ho)
And the time it takes to reach a predetermined risk level
Is corrected, and the installation height (H) is corrected.
A threshold correction unit that calculates a risk threshold (R) of the above, and calculates a value of a risk that is a time until the predetermined risk level is reached based on a change tendency of the analog detection signal obtained from the past to the present. A fire determining unit for performing a fire determining process by comparing the risk threshold (R) corrected by the threshold correcting unit with the value of the risk; and displaying an alarm display based on a fire output of the fire determining unit. A fire alarm device comprising an alarm display unit for performing the alarm.