JPH0196795A - Fire detector - Google Patents

Abstract

PURPOSE:To correctly and automatically sense the occurrence of a fire by passing only a reference wavelength to show the existence of CO2 in a flame and a comparison wavelength not under the influence of the fire out of radiant energies radiated from the partial areas of the respective supervising parts. CONSTITUTION:The radiant energies radiated from the respective partial areas are converged on a converging means 7 for the respective partial areas. The converging means 7 passes specific wavelengths, that is, the reference wavelength lambda1 of the radiation (absorption) band of CO2 generated in the flame and comparison wavelength lambda2 of the radiation (absorption) band of, for example, 'soot' of the flame which is not under the influence of the fire and converges them respectively on different places. A scanning means 8 fetches successively the radiant energy of the reference wavelength and the comparison wavelength of a partial area S1 from respective detector 31A and 32A and sends them to a comparison calculating part 51 in an operation means 5. This comparison calculating part 51 calculates the ratio of the above-mentioned reference wavelength and comparison wavelength and executes successively the detection of the fire in the partial areas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fire detector capable of detecting a fire at a long distance by capturing radiant energy emitted from within a predetermined monitoring area.

[Conventional technology] Conventionally, in order to detect fires that occur far away, the monitoring area for fire detection is divided into multiple partial areas, and the radiant energy from these partial areas is sequentially captured by a radiation thermometer. Fire detectors are known.

Figure 4 shows the monitoring area S at this time divided into multiple partial areas Sl.
, S2. S3. -Sn is shown.

Further, FIG. 5 shows the configuration of a conventional fire detector of this type.

Figure 5 shows 53 (A), (1) is a lens that captures radiant energy for each partial area, and (2) shows that the radiant energy captured by lens (1) is transmitted to a specific wavelength of the radiant energy for each partial area. sector (3) is a detection element such as a thermopile that detects radiant energy of a specific wavelength that has passed through the filter (21) and outputs an electrical signal corresponding to this radiant energy;
(4) is a preamplifier that amplifies the electrical signal output from the detection element (3); (5) is a calculation unit that calculates the signal output from the preamplifier (4) to determine whether a fire has occurred; (6) ) is a motor that rotates sector (2).

Next, the operation will be explained.

Each partial area Sl, S2. The radiant energy emitted from -3n is distributed to the lens (1) and guided to the sector (2).

Here, when the motor (6) is rotated and the filter (21) of the sector (2) is sequentially moved, only the radiant energy of a specific wavelength among the radiant energy is sent to the detection element (3) in each partial area. Enter.

The detection element (3) outputs an electrical signal according to the radiant energy, and the preamplifier (4) amplifies the electrical signal output from the detection element (3) and outputs it to the arithmetic unit (5). A calculation unit (5) calculates the output of the preamplifier (4) and determines whether a fire has occurred within the monitoring area.

FIG. 6 is a diagram showing the relationship between wavelength and relative intensity of radiant energy.

As shown in the figure, incandescent light bulbs, fluorescent lights, sunlight, flames, etc. each exhibit a unique spectral distribution, so in order to detect a fire, if you capture the radiated energy of a predetermined wavelength, you can detect the presence of flame within the monitoring area. You can know.

By the way, the spectral distribution of flame has two peaks at wavelengths of 2 μm and 4.4 μm, as shown in Figure 4.

This is caused by secondary radiation called resonance radiation due to the presence of carbon dioxide CO2 generated when this hydrocarbon with a peak wavelength of 4.4 μm is burned.

Therefore, fire detection can be performed by knowing the levels of radiant energy of these two wavelengths.

[Problems to be Solved by the Invention] As described above, the conventional fire detector rotates the sector (2) with the motor (6) and extracts the radiant energy of each partial area from the filter (21) of the sector (2). Since they were removed one after another, mechanical failures were likely to occur and the lifespan was short.

In addition, even if the level of radiant energy of a fire could only be determined, it would be susceptible to the effects of carbon dioxide gas present in the air and light emitted by tree leaves, resulting in frequent malfunctions.

This invention was made to eliminate the above problems.
The objective is to obtain a fire detector that has a long life, is less likely to malfunction, and has fewer malfunctions.

Of the radiant energy from the partial area, only the reference wavelength that indicates the presence of CO2 in the flame caused by the fire and the comparison wavelength that is not affected by the fire are allowed to pass through, and each detection is provided correspondingly to each partial area. A detection means (IA) that detects the radiant energy of the wavelength that has passed through each partial area using an element, and scans the radiant energy supplied to each of the detection elements for each partial area to detect the reference wavelength and the comparison. The present invention is characterized in that it includes a determining means (2A) that determines the ratio of radiant energy of wavelength for each partial area and determines whether there is a fire within the monitoring area.

[Function] The detection means (IA) according to the present invention allows only the reference wavelength, which indicates the presence of CO2 in the flame, and the comparison wavelength, which is not affected by the fire, to pass among the radiant energy emitted from each partial area. The passed radiant energy is detected by each detection element for each partial area. Here, the means of judgment (2
A) scans the radiant energy supplied to each of the detection elements for each partial area, and calculates the ratio of the radiant energy of the reference wavelength and the comparison wavelength for each partial area to detect fires within the monitoring area. Perform detection.

[Example] Peng An embodiment of the present invention will be described below with reference to the drawings.

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

In the figure (7), the reference wavelength for detecting the presence of 002 in the flame caused by the fire and the comparison wavelength that is not affected by the fire are separated from the radiant energy from each partial area and concentrated in different locations. Light condensing means (31A
), (32A) is a detector constructed by arranging a plurality of detection elements each installed in a place where the light is focused by the light collecting means (7), and (8) is a detector configured by arranging a plurality of detection elements arranged in each place where the light is focused by the light collecting means (7). A scanning means (51) is a comparison calculation unit which calculates the ratio of radiant energy of the reference wavelength and the comparison wavelength for each partial area.

Here, a condensing means (7) and a detector (31A),
(32A) constitutes the detection means (IA), and the scanning means (8
) and the comparison calculation section (51) constitute the determination means (2A).

Next, the operation will be explained.

First, the radiant energy emitted from each partial area is focused onto the condensing means (7) for each partial area via the lens (1).

This condensing means (7) uses a specific wavelength of the condensed radiant energy, that is, a reference wavelength (λ1) of the emission (absorption) band of CO2 generated in the flame, and a reference wavelength (λ1) of the emission (absorption) band of CO2 generated in the flame. Comparison wavelength (λ2) of soot emission (absorption) band
and focuses the light on different locations. This is constructed using, for example, a beam splitter and a filter. As a result, the radiant energy of the reference wavelength and comparison wavelength for each partial area is input to each detection element of each of the detectors (31A) and (32A).

Here, the scanning means (8) first scans each detector (31A) with radiant energy of the reference wavelength and the comparison wavelength in the partial area S1.
, (32A), the next step is to input the radiant energy of the reference wavelength and comparison wavelength of the partial area S2 to each detector (32A).
1A) and (32A), each partial area St, S2 . =Sn reference wavelength and comparison wavelength are taken in and output to the calculation means (5).

The comparison calculation section (51) in the calculation means (5) is connected to the scanning means (8).
), the ratio of the radiant energy of the reference wavelength and the comparison wavelength that are sequentially input is calculated, and the detection of fire within the partial area is sequentially determined. The reference wavelength used at this time is 4.5 μm,
The comparison wavelength is 3.8 μm.

Here, the radiant energy at the reference wavelength of 4.5 μm and the comparison wavelength of 3.8 μm will be explained.

FIG. 2 is a diagram showing the relationship between the wavelength band radiated (absorbed) by CO2 present in the air and the wavelength band radiated (absorbed) by the flame 002 generated by combustion.

As shown in the figure, the wavelength band in which C02 in the flame is radiated (absorbed) has the property of shifting to the longer wavelength side with respect to the wavelength band in which C02 in the air is radiated (absorbed).

Therefore, as shown in the figure, if only the radiant energy with a wavelength of 4.5 μm is captured through a filter, CO present in the air can be
It can be seen that it is not affected by 2.

As can be seen from the figure, the allowable range for this reference wavelength of 4.5 μm is approximately ±0.05 μm. Furthermore, the radiant energy at a comparative wavelength of 3.8 μm is in a wavelength region of a transmission band that is not affected by fire such as soot present in a flame.

The allowable range for this comparison wavelength of 3.8 μm is looser than the reference wavelength, but approximately ±0.2 μm is appropriate. FIG. 3 shows what numerical values are obtained for each measurement source when the ratio of the wavelength of 4.5 μm and the wavelength of 3.8 μm is calculated in this way.

As shown in FIG. 3, the ratio when flames are detected and the ratio when flames are not detected are different, so it can be seen that fires within the monitoring area can be detected.

[Effects of the Invention] As explained above, the present invention extracts the radiant energy of the reference wavelength and the comparison wavelength for each area and supplies it to each detection element, and sequentially scans the output from each detection element to obtain the reference wavelength. Since fire detection is performed based on the ratio of the radiant energy of the wavelength and the comparison wavelength, a fire detector with a long life, less chance of failure, and less malfunction can be obtained.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing an embodiment of the present invention, Figure 2 is a diagram showing the relationship between the transmission characteristics of C02 in the air and the radiation intensity of the flame, and Figure 3 is a diagram showing the measurement wavelength and comparison wavelength for each measurement source. Figure 4 shows how the monitoring area is divided into multiple partial areas. Figure 5 shows the configuration of a conventional fire detector. Figure 6 shows the wavelength and radiation. FIG. 3 is a diagram illustrating the step and grandchild of the relative intensity of energy. (1)-lens, (2)-sector, (31A),
(32A) - Detector, (8) - Scanning means, (51) - Comparison calculation section, (IA
)-detection means, (2A)-judgment means. Fig. 3 Fig. 4, lj shrimp cost 2d mu saba

Claims (1)

[Claims] (1) Divide the monitoring area into multiple partial areas, capture radiant energy of a specific wavelength among the radiant energy emitted from within these partial areas, and measure this captured radiant energy to prevent fires within the monitoring area. Of the radiant energy from the plurality of partial areas, the fire detector that detects it passes only the reference wavelength that indicates the presence of CO_2 in the flame caused by the fire and the comparison wavelength that is not affected by the fire, and a detection means that captures the radiant energy of the wavelength that has passed through each partial area using each detection element provided correspondingly to the detection element; A fire detector characterized in that it is equipped with a determination means for determining a fire within a monitoring area by determining the ratio of radiant energy of the reference wavelength and the comparison wavelength for each partial area.