JPH0562081A - Fire detecting system - Google Patents

Abstract

PURPOSE:To detect even the comparatively small fire source as a fire by comparing the total value of the temperature rise value per the unit time of respective temperature measuring points and the threshold set beforehand. CONSTITUTION:At the ceiling part of a side wall 3 of a gateway 2, an optical fiber sensor 5 is laid along the length-wise direction of the gateway 2, and at the optical fiber sensor 5, a temperature measuring point Pi is provided at equal intervals. When the gross heating value to generate a fire source 7 is diffused to space 6, the temperature measured value at each temperature measuring point Pi respectively rises in accordance with the diffusion. By the extent of the diffusion, the temperature measured value shows the respectively different value. Then, each temperature rise value per the unit time is obtained, the temperature rise value of each measuring point Pi is totaled, and then, in no relation to the size of the diffusion, the total value approximately in proportion to the gross heating value is obtained. Thus, when the obtained total value exceeds the threshold, it is judged that the fire occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel fire detection system, and particularly to a fire source even if it is a relatively small fire source in a space having a limited spread such as a tunnel or a cave. The present invention relates to a fire detection system capable of approximately catching the total amount of heat generated and detecting it as a fire.

[0002]

2. Description of the Related Art In a fire detection system for detecting a fire by detecting an ambient temperature, a temperature sensor has been conventionally provided to measure a temperature, and an upper limit value of temperature is set and the measured value exceeds the upper limit value. There are known a constant temperature type heat sensing method that determines a fire and a temperature rise rate detection method that determines a fire when the temperature rise value of the above measured value per unit time exceeds a certain value. ing. Here, it goes without saying that the temperature upper limit value and the temperature increase upper limit value are set to values exceeding the normal temperature fluctuation range and the measurement fluctuation range.

[0003]

However, when the fire source is smaller than the space in which the fire detection system is installed and is far from the temperature sensor, the combustion gas generated from the fire source or the warm air is generated. The high temperature gas such as the above diffuses before reaching the temperature sensor, and at the position of the temperature sensor, the temperature rises only to such an extent that the normal temperature fluctuation range is not exceeded. Therefore, it is not possible to detect a fire consisting of a small fire source by using either the constant temperature type heat sensing method or the temperature rise rate detecting method. In this case, the fire grows, the spread of the fire starts, and the fire is finally detected. That is, there was a problem that the discovery of the fire was delayed.

Therefore, an object of the present invention is to solve the above problems and to provide a fire detection system capable of detecting a fire even with a relatively small fire source.

[0005]

In order to achieve the above object, the present invention provides temperature measuring points in a space at substantially equal intervals and obtains temperature rise values per unit time at these temperature measuring points. Are summed, and the fire is detected by comparing the total value with a preset threshold value.

[0006]

With the above structure, when the temperature rise at each temperature measurement point per unit time is obtained and these are summed, a total value approximately proportional to the total calorific value in the space is obtained, as will be described later. .. A threshold is set in advance for this total value, and a fire is detected by comparing the two. In this way, even if the fire has a small fire source, even if the heat is diffused, it can be detected based on the total value that is approximately proportional to the total amount of heat generation, and therefore it is detected as a fire.

Here, in a passage-like space having a substantially constant cross-sectional area, a plurality of measurement points are provided at substantially equal intervals, and the sum of temperature rise values per unit time at each measurement point is calculated. , This total sum is approximately proportional to the total heat generation amount in this passage-like space. Focusing on this proportional relationship, a threshold value is set for the sum of temperature rise values at unit time at each measurement point, and if the sum exceeds the threshold value, it can be judged as a fire. Therefore, the judgment can be made according to the total amount of heat generation, and even a fire having a small fire source can be detected.

In this way, the total amount of heat generated by the fire source is approximately caught, and the fire having a small fire source is detected, so that the fire can be detected early.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In carrying out the present invention, an optical fiber temperature radar (distributed optical fiber temperature measuring device, hereinafter referred to as FTR) capable of measuring temperature at equal intervals along an optical fiber.
Is suitable. The FTR allows light to pass through an optical fiber and measures the temperature by detecting the effect of the ambient temperature of the optical fiber on the light with an optical sensor. It is possible to measure the temperature distribution linearly along the optical path of the optical fiber. it can. In one embodiment of the invention described below,
The temperature measurement points are provided at equal intervals using the FTR.

FIG. 1 is a conceptual diagram of a fire detection system 1. The tunnel 2 has an arch-shaped cross section as shown in FIG. 2, and has a space 6 which is defined by a side wall 3 including a ceiling portion and a floor portion 4 and which is elongated. The gallery 2 is formed to have a substantially equal cross-sectional area over its entire length. An optical fiber sensor 5 is laid on the ceiling of the side wall 3 of the gallery 2 along the longitudinal direction of the gallery 2. The optical fiber sensor 5 is provided with temperature measurement points P for measuring temperature at equal intervals. Although not shown, the optical fiber sensor 5
An FTR is connected to the end of the optical fiber sensor 5, and the temperature distribution along the optical fiber sensor 5 can be observed. That is, the i-th measurement point Pi (i = 1, 2, 3, ...)
The temperature at can be represented by the measured value Ti. This measured value is measured and updated at regular intervals. At the same time, the difference from the previous measured value is obtained, and the temperature rise value dTi at each measurement point Pi is calculated.

On the other hand, a threshold value Θ for detecting a fire
Is set in advance so as to correspond to the minimum heat generation amount that can be determined to be a fire while exceeding the normal temperature fluctuation range.

Next, the operation of this embodiment will be described.

It is assumed that a fire occurs in the gallery 2 and the fire source 7 is small and far from the temperature measurement point Pi. The total calorific value Q generated by the small fire source 7 diffuses into the space 6 of the tunnel 2 mainly by high temperature gas such as combustion gas and ambient air. In this way, when the total heat generation amount Q generated by the fire source 7 is diffused in the space 6, the temperature measurement value Ti at each temperature measurement point Pi increases in accordance with this diffusion. The temperature measurement values Ti show different values depending on the degree of diffusion. Therefore, each temperature rise value dTi per unit time is obtained, and the temperature rise value dTi at each measurement point P is obtained.
By summing up, the total value Σ that is substantially proportional to the total heat generation amount Q can be obtained regardless of the magnitude of diffusion.

In this way, when the total value Σ obtained by summing the temperature rise values dTi at the respective measurement points Pi exceeds the threshold value Θ, it is determined that a fire has occurred.
That is, even a fire that has a small fire source 7 and is far from the temperature measurement point can be detected, and early detection of the fire becomes possible.

Here, the results of comparison between the fire detection system according to the present invention and the conventional fire detection system using the constant temperature type heat detection method and the temperature rise rate detection method by a simulated fire experiment will be shown. Table 1 shows the time until fire detection, the average value of the times, and the standard deviation value in each fire detection system when the number of trials was seven. The simulated fire experiment was conducted by placing a fire source on a belt for a belt conveyor of 0.25 to 0.5 m ² and simulating a relatively small fire while changing its position. The same FTR is used as a device for measuring temperature. The CASE number in the table indicates the number of trials of this experiment.

[0017]

[Table 1]

As shown in Table 1, the fire detection system according to the present invention has the shortest time until fire detection in any trial, and the average value is also small. This indicates that the fire detection system according to the present invention can detect a fire earlier than the conventional fire detection system. Furthermore, if attention is paid to the term of the standard deviation value, it can be seen that there is little variation in the time required to reach the maximum detection value. This shows that the operation of the fire detection system according to the present invention is reliable and highly reliable. Thus, from the results of the simulated fire experiment,
The fire detection system according to the present invention makes it possible to detect a fire quickly and reliably.

As described above, in the present invention, the judgment is not made independently based on the measured values of only one point, but the measured values of a large number of measuring points are comprehensively judged. It is now possible to indirectly capture not only changes in temperature but also increases in heat. By detecting a fire based on an increase in the amount of heat, it has become possible to detect even if the size of the fire is smaller than that in space.

In the present embodiment, the tunnel 2 is formed so that the cross-sectional areas are substantially equal over the entire length thereof, but in the case where the cross-sectional area is not constant or there is unevenness or a curved space. Even if there is, it is easy to obtain the total value Σ that is substantially proportional to the total heat generation amount Q by a calculation method that takes the shape into consideration.
Therefore, the fire detection system 1 according to the present invention can be provided in any space defined by a predetermined shape and size such as a tunnel, a cave, a tunnel, an underground passage, a room, and a corridor.

[0021]

The present invention exerts the following excellent effects.

(1) A fire can be detected early.

(2) A fire can be found in a wide space.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a schematic view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Fire detection system 6 Space Ti temperature measurement value dTi temperature rise value P, Pi temperature measurement point Θ threshold value

Claims (1)

[Claims] 1. A fire detection system for detecting a fire by detecting an ambient temperature in a predetermined space, wherein temperature measuring points are provided at substantially equal intervals in the space, and temperature rises at a unit time of each of these temperature measuring points. A fire detection system characterized by detecting a value, summing these values, and comparing the total value with a preset threshold value to detect a fire.