JPS5932096A - Flame detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a flame detection device that detects a flame regardless of whether it is outdoors or indoors by detecting the characteristic radiation emitted from a flame. relates to a flame detection device that can also detect flames accompanied by black smoke.

(2) Background of the Technology The radiation from the flame generated when combustible materials oxidize and burn in the air contains radiation with specific wavelengths determined by the type of combustible material. Among them, as shown in curve A shown in Figure 1, where the horizontal axis is the wavelength λ and the vertical axis is the intensity I, the spectrum is unique to all oxidative combustion and is emitted from carbon dioxide gas generated during oxidation. Infrared rays have a peak around 4.4 am.

Such flame detection devices that detect flames by detecting infrared rays around 4.4 μm already exist, but there are various problems as described below, and it is difficult to improve the sensing ability and reliability. I'm a promising talent.

It is desirable to have a flame detection device that can detect even flames accompanied by small amounts of black smoke.

(3) Prior art and problems As mentioned above, flame detectors that simply detect infrared radiation around 4.4 μm are not capable of detecting infrared light around 4.4 μm emitted from low-temperature radiating objects, etc., as shown by curve B in Figure 1. 0 Also detects infrared rays and 1-
1. There is a peak point where the flame detection malfunctions.

As a solution to the above problem, the example shown in Fig. 1 is used.
A band pass filter that passes the radiation near 4.411711 and a band pass filter that passes the radiation near J (= J) is provided, and the difference in intensity of the radiation that has passed through both filters is detected. There is a flame detection device that detects as a flame when the spectrum of wavelengths characteristic of a flame becomes an integrated spectrum (for example, Japanese Patent Publication No. 54-9336
order. There is a flame detection device that detects flame by using the above-mentioned spectrum without exhibiting any fluctuation.

However, such a flame detection device has the following problems. As an example, as shown in Fig. 1, in the case of a low-temperature radiating object that does not emit a flame of about 100 degrees Celsius, such as a tin roof in summer, the difference Δ in the radiation intensity near 4.4 μm and near 4.08 m is The difference when ■ is a flame is not sufficiently significant compared to △work. That is, if the intensity difference is set small to increase sensitivity to flames, it will malfunction with respect to low-temperature radiating objects, and if the intensity difference is set large to prevent malfunctions, flames will not be detected.

Another problem is that the infrared radiation near 4,41rtn emitted by the flame is absorbed by carbon dioxide gas in the air, and if the distance 1t between the flame and the flame detector increases, the wavelength will naturally increase to 4.4μ.
The detection sensitivity of the radiation group near m may drop and flames may not be detected.

Another problem that has arisen is that when heavy oil or gasoline with a high carbon content burns in the air, it generates a large amount of carbon dioxide gas, which absorbs radiation in the vicinity of 4.4 μm, making it difficult to detect flames. It becomes difficult. This means that if the distance between the flame and the sensor is large, the above problems will be compounded.

Another problem 7 is that sunlight may reflect on a road after rain and cause fluctuations, or the flashing lights of a patrol car may cause a difference in radiation intensity, leading to malfunctions.

(4) Object of the invention The present invention &j: To improve the reliability of flame detection by removing the influence of radiation emitting objects other than flames existing indoors or outdoors,
It is an object of the present invention to provide a flame detection device that improves the sensitivity of ordinary flame detection and can accurately detect flames even when the flames are accompanied by black smoke.

(5) Structure of the Invention The present invention provides an adaptive control method C that statistically processes the intensity of infrared rays with a wavelength specific to a flame and the time course of infrared rays with a wavelength near the wavelength. This was done based on the idea of increasing the flame sensing ability by removing the effects of infrared rays other than the flame, and in the present invention, the flame detects radiation of a specific wavelength emitted by the flame and generates a corresponding electric signal. a first radiation detection means for receiving radiation other than the characteristic wavelength emitted by the flame and converting it into a corresponding electrical signal; a first arithmetic comparison means for determining whether the deviation between the average value of the output signal and its instantaneous value is greater than or equal to a predetermined value; and the average value of the output signal of the second radiation detection means over the deviation and the predetermined period. and a second calculation comparison means for determining whether the proportionality of the deviation of the instantaneous value and the deviation thereof is equal to or greater than a predetermined value; third arithmetic comparison means for determining whether the ratio between the average value of the signal and the difference between the maximum value and the minimum value is within a predetermined value; 1
unevenness detecting means for detecting whether there are peaks or valleys in the change in the output signal of the radiation detecting means of the first radiation detecting means; A flame detection device is provided, which outputs a flame detection signal based on the results of determination in the second and third calculation means and the unevenness detection means.

(6) Embodiment of the invention FIG. 2 shows a circuit diagram of a flame detection device as an embodiment of the invention.
'l'r diagram is shown.

Referring to FIG. 2, the flame detection device fiqt of the present invention detects radiation from a radiator 0 accompanied by a flame t:V
r 1, logical method 3 which is calculated by borrowing from the detection part 2, i which compares and judges the number from the logical method 1 and song 2
t+ section 4, and the information section 5 to 4 which issues the 1゛11'' report.
1i, 7 will be completed.

Detection unit] is a wave l, ελ to the right of 'R+' to the flame of the radiator 6.
1. In the example shown in FIG. 1, a first band-pass filter 11 that passes 4.4 trm nearby radiation; a first photoelectric conversion that converts the signal from the band-pass filter into an electrical signal; A first radiation detection system consisting of a detector 12, an AD converter 13 that converts an analog signal from the photoelectric converter into a digital signal, and a radiation gland different from the wavelength λ1 described above and located near the wavelength λ1 for flame detection. In the example shown in FIG. 1, the wavelength λ2 has a discriminability of 4.
It consists of a second radiation detection system consisting of a second bandpass filter 14 that passes radiation around 0 μm, a photoelectric converter of E+γ2] 5, and a second AD converter 16.

The second photoelectric converter 15 and the second AD converter 16 are similar to the first photoelectric converter 12 and the first AD converter]3, respectively.

Therefore, the output of the first radiation detection system 1 -C is the radiation of wavelength λ1 as a digital signal 813, and the output of the second radiation detection system is the radiation of wavelength λ2 as a digital signal r1t. S ] G is applied to the logic 3↓l calculation unit 2, respectively.

The logic operation section 2 is composed of the following. 1) Buffer memories 21 and 28o store the reception of the signals S13 and S16 described in 1. Signals S]3, S], and 6 are sequentially stored in the buffer memories 21 and 28, respectively, and after a certain period of time has elapsed, they are stored in the subsequent stage. The first clock oscillator 27o generates a lock signal for sending out the signals stored in the circuits of the first clock oscillator 27o.The average value AV of the signals sent out from the buffer memories 21 and 28.

AV] and second average value calculating circuits 22 and 29 for calculating the current radiation values for the wavelengths λ1 and λ2 obtained as described above, that is, the instantaneous values V. ,VH(4
No. 8 S13, 516) and the wavelength λ1. obtained in the average value calculation circuits 22 and 29. Average value of radiation of λ2 AVo
, deviation σ from AVR. , σ□ first and second difference circuits 25.30° First deviation σ. and the second deviation σ□.

The logic operation section 2 is further composed of the following. The oscillation frequency of the first clock oscillator 27 described above is higher than the sieving frequency, and therefore the short period clock signal is sent to the first buffer memory I.
Based on the signal sent out from the buffer memory 21 by the clock frequency of the second clock oscillator 32o applied to the second clock oscillator 32, the average value AV
o', and the buffer memory 21 within the interval of the second clock pulse.
of the signal sent from! fk dog value IIn & engineering and minimum value engineering □□. Maximum/minimum detection circuit 23° that detects the maximum value max and minimum value max and minimum value □, □□ from the maximum/minimum detection circuit 23
The third difference circuit 24 calculates the difference σ from the third average value calculation circuit 33 to the value AV. ' and the difference σ□ from the third difference circuit 24. A second division circuit 26 detects whether or not there is a peak or valley in the signal S13 within the period of the second clock pulse. or if there is a valley, logical "l"
The signal unevenness detection circuit 34 outputs the signal σc R1, R2, S34 obtained as described above to the determining section 4.

The judgment unit 4 outputs logic = [1] when the deviation σC is a value α, for example, 3 or more, preferably 7 or more.
The second comparator circuit 42 outputs logic = "1" when the ratio R2 is within the range β1 to β2, for example 0.2 to 1.0. For example, 0
．． 7 or more, the third comparator circuit 43 outputs logic = "1", and the second comparator circuits 41 and 4'2
an AND gate 44 which logically ANDs the logical output signals of , an AND gate 46 which logically ANDs the logical output signal from the signal unevenness detection circuit 34 and a third logical output signal, and an AND gate 46 which logically ANDs the logical output signals of the AND gates 44 and 46; Multiply and gate 4
Consists of 5.

If the output logic of the AND gate 45 is "[]", the alarm unit 5 is activated to notify that a flame has been detected.

The alarm unit 5 is the same as the conventional one, for example, by using a buzzer or lamp, or outputting a flame signal to the outside.

In other words, the logic of flame detection determines that a flame exists and issues a good report when the following formula and conditions are satisfied at the same time.

Vo-AV,, ≧α・Song・(1) C −≧γ ・・・・・・ (4) +7R In the initial state, the clock oscillator 27 sends a certain number of signals 813 and 816 to the backup memory 21.28. Note 1. The clock pulses are not oscillated until the backup memory 21.28 is stored.
From 3.16, each time new data is input to the buffer memory 1J21, 2B, it is sent to the subsequent circuit.

The buffer memory 21.28 stores data at a constant f, and when the latest data (signal S13, 516) is input, the oldest data is sent out to the average value calculation circuit 22.29. The average falling value will also be updated.

In addition, the clock oscillator 27 and i-1:32 receive the signal S13. A clock pulse may be generated each time S16 is stored in the buffer memory 21, 28, and may be sent to the subsequent circuit at each cycle of the clock pulse. In that case, after receiving the clock pulse, the buffer memo v
2x, 2s signal S13゜Clear S16 11.7
Ijf constant number of signals S13゜S16 to backup memory 2
1.28.

The basic principle of the above flame detection will be described below by giving an example.

In Figure 3, the 4Jl axis is the time t1 vertical axis is the radiation intensity factor, and υ
, the value of radiation around wavelength λ1, e.g. 4.4 μm vc, and the value ■R of radiation around wavelength λ2, e.g. 4.0 μ7n
Curves AVo, AV□4, which plot the average values of M, VC, and vo in Figure 2 in circuits 22 and 29 and fC, AVo, AV□4, Wavelength λ1 when a flame occurs. The value V of the radiation of λ2. This is an illustration of l, v, (/.

Incidentally, FIG. 3 exemplifies the case where a tin roof on a summer day is nearby as a low-temperature radiating object, and shows the case where the radiation intensity changes with the passage of time.

In the case of a normal flame, as is clear from the characteristic diagram shown in FIG.
V within the period. ' has a peak or valley and satisfies the third equation. Detection is performed with even higher precision. In this case, what about the second equation above? i! l! Add I. It is assumed that flame exists if the above conditions are satisfied. This is more accurate than conventional detection and can improve detection sensitivity.

Furthermore, the present invention is adapted to enable the detection of flames accompanied by black smoke. Figure 4 shows the wavelength λ1 of moxibustion accompanied by black smoke. λ2
■ Radiation. , ■□ is given by Bron lt, where the horizontal axis is time tX and the vertical axis is radiation intensity ■.

Even if the flame is accompanied by black smoke, Equations 1 and 3 hold true.

As shown in Figure 4, the radiation fluctuates and dies, and empirically, aO/(, #1, when applied to the fourth equation, γ(#0.
7) or more, and β1('';0.2) <(Imaw
It is known that -'m1n)/AM(3'<β2(纺1).

From the above, it is possible to detect a flame accompanied by black smoke by establishing the first to fourth equations.

Next, we will discuss low-temperature radiating objects. The radiation intensity from low-temperature radiating objects fluctuates as shown in Figure 3, but
The average value Av obtained by the average value calculation circuit 22 in FIG.
o and instantaneous value ■. deviation σ from ]: Slight. Therefore, Equation (1) does not hold, and it is not considered that flame exists. Therefore, malfunctions due to radiation from low-temperature radiating objects can be prevented.

Also, for example, even if radiation from a low-temperature radiating object temporarily satisfies Equation 1 due to transient noise (17), it is not possible for other Equations 2 to 4 to hold simultaneously. This prevents malfunctions caused by transient noise.

Furthermore, we will discuss the case where the fluctuation of sunlight reflected on a road after rain or the rotating position of a patrol car causes a difference in radiation intensity.'6. Such fluctuations, radiation,
The average value 61 in Fig. 2 is calculated for the period of change in the radiation intensity (calculation circuits 22 and 29 calculate the average value in a fairly long period, for example, about 10 minutes. Therefore, the average value of fluctuation and radiation intensity is The difference from the instantaneous value is within the range, and as with low-temperature radiation objects, the first equation does not hold. A temporary C4C difference occurs) In this case, the other equations 2 to 4 also hold at the same time. There's nothing to do.

From the above, even in this case, there will be no malfunction.

The present invention may be carried out in various modifications other than those described above. For example, the logical operation section 2 and the lid? in FIG. It is also possible to return 1iT to part 47 microprocessor. In the above example, we will discuss the case where digital signal processing is used as a living device.Bev @ can be analog (No. 1 processing or hybrid type signal processing).Furthermore, the average value calculation circuit is a simple moving average. Although the case where the AD
Signal S13. from converter 13.16. It is possible to provide a timing pulse when importing S16 into the buffer memo 1J21, 25.

(6) Effects of the Invention As is clear from the above, according to the present invention, the influence of radiation-emitting objects other than flames existing inside or outdoors is removed, the reliability of flame detection is improved, and the reliability of flame detection is improved. To provide a flame detection device which can improve the sensitivity of flame detection and can detect flames in the main image 6 even if the flame is accompanied by black smoke.

[Brief explanation of drawings]

Fig. 1 is a radiation intensity characteristic diagram, Fig. 2 is a schematic diagram of a flame detection device as an example, and Fig. 3 is a characteristic diagram used to explain flame detection of the flame detection device il of the present invention. Figure, ;4'
Figure y4 is another characteristic diagram used to explain flame detection by the flame detection device of the present invention. (sign, 1)l light) 1...'bij exit i;B, 11. 14...
・Pantono (Sfili, 12, 15...Photoelectric converter, 13.1 (5...AD converter, 2... Theory) 1
1! 'tL't:i'>: f%, 21,28
...ノ(sofa, memory, 22, 20.33... average (: li calculation circuit, 23... maximum/minimum detector, 24, 25.3 (1... difference circuit, 26,: N ...Divided Ω-times 1.6, 27.32...
・Clock source 11 34... Signal unevenness detection circuit,
4... Judgment section, 41-43... Comparison circuit, 44-46... AND gate, Death 9 reporting section, 6...
·flame. Patent Applicant Nippon Bisho Co., Ltd. Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Akira Yamaguchi

Claims (1)

[Claims] 1. A first radiation detection means that receives radiation of a specific wavelength emitted by the flame and converts it into a corresponding electrical signal; a second radiation detection means for converting into an electrical signal; a first radiation detection means for determining whether the deviation between the average value of the output signal of the first radiation detection means over a predetermined period and its instantaneous value is greater than or equal to a predetermined value; arithmetic comparison means, second arithmetic comparison means for determining whether a ratio between the deviation and the deviation between the average value of the output signal of the second radiation detection means over a predetermined period and the deviation of its instantaneous value is greater than or equal to a predetermined value; , determining whether the ratio of the average value of the output signal of the first radiation detection means over a period of length different from the predetermined period and the difference between the maximum value and the minimum value is within a predetermined value. 3, and unevenness detection means for detecting whether there are peaks or valleys in the change in the output signal of the first radiation detection means over a period of length different from the predetermined period. and the above-mentioned No. 1. A flame detection device configured to output a flame detection signal based on the results of determination by second and third arithmetic comparison means and the unevenness detection means.