JP3205889B2 - Flame detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame detector for detecting a flame generated by a hydrocarbon fire such as a fire of various machine tools or a domestic fire to which various kinds of combustible materials such as lubricating oil are attached. It concerns the device.

[0002]

2. Description of the Related Art An electromagnetic wave radiated from a flame generated by a hydrocarbon fire contains a wide range of components from ultraviolet rays to far infrared rays. FIG. 5 is a spectrum curve of a flame in which the horizontal axis represents the wavelength (μm) of the radiated electromagnetic wave and the vertical axis represents the relative intensity (%). As is clear from FIG.
It is well known that there is an infrared ray having a peak near 4.3 (μm) due to the resonance radiation of carbon dioxide (CO ₂ ) generated during combustion as a spectrum specific to all combustion flames regardless of the kind of combustibles. ing.

[0003] Conventionally, a flame detection device generally used is a high-sensitivity photoelectric tube using an ultraviolet ray (hereinafter referred to as UV).
UV) that can detect the infrared rays (hereinafter referred to as IR) near 4.3 (μm) using the CO ₂ resonance radiation peculiar to the flame as described above. The IR type which detects the peak level or the level of a plurality of points before and after 4.3 (μm) as the center is known, but the former UV type is very sensitive and can detect instantaneously. On the other hand, malfunctions are likely to occur due to the discharge of various discharge tubes such as lighting fixtures, sparks of welding, and the like, and the latter IR type has an IR near 4.3 (μm) emitted from a high-temperature object other than a flame. May also be detected and malfunction may occur. Therefore, in view of the necessity of ensuring the predetermined flame detection without causing malfunctions due to various disturbance elements as described above, the UV type and the IR type are suitable for installation environments of radiation sources other than fire. The fact is that it is selectively used depending on the situation, and its versatility is very poor.
Among the IR expressions, a multi-wavelength expression that detects the level of a plurality of points before and after 4.3 (μm) as a center is:
Although a predetermined detection function can be exhibited even if there is a fluctuation peculiar to the flame, it is necessary to install an optical filter at each of a plurality of points, which is extremely expensive and impractical.

In order to solve the above-mentioned drawbacks of the UV or IR independent detection device, conventionally, for example, as disclosed in Japanese Patent Publication No. 3-35720, both UV and IR are detected. In addition, a UV / IR ratio judging type flame detecting device configured to calculate the ratio of the two and judge whether the ratio is within a specific range and detect the flame, and further, Japanese Patent Application Laid-Open No. HEI 3-174699. As disclosed in Japanese Unexamined Patent Publication, both the UV amount and the IR amount are continuously detected for a certain period of time, and when each of the UV amount and the IR amount exceeds a predetermined level fixedly set in advance. UV / IR configured to determine a flame based on the logical product of two output signals and output an alarm or other notification signal
Flame detectors of the type have already been proposed.

[0005]

However, in the above-mentioned conventional flame detection device of the UV / IR ratio judgment type, the UV
Flammables can be identified from the change characteristics of the ratio of flammable materials to IR, but depending on changes in the installation environment, for example, when smoke is floating in the air or not, or depending on the type of flammable materials, UV and IR When the ratio greatly changes, there is a problem of a malfunction such that an alarm is issued even though a flame actually occurs. Also, the latter UV
In the / IR type flame detection device, although the ratio of UV and IR emitted differs depending on the type of combustible material, since each determination level is fixed, a flame detectable according to the type of combustible material. Will differ in size,
It is difficult to apply to general fires in general. In addition, since it has an integration function such as continuous detection for a certain period of time to distinguish UV and IR emitted from the flame from UV and IR emitted from other radiation sources, quick response is achieved. And it is not possible to quickly detect the small flame that is the cause of the fire. Further, it is conceivable to use a device equipped with a flame analyzer such as a spectrum analyzer as a UV and IR detection sensor in order to cope with the change in the ratio. In this case, however, the sensor itself becomes very expensive, and the apparatus becomes expensive. Soaring overall costs are inevitable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and is capable of detecting a flame with high sensitivity, accuracy, and speed over a wide range of general fires while suppressing an increase in cost. It is intended to provide a detection device.

[0007]

In order to achieve the above object, a flame detecting device according to the present invention is provided with a UV radiated from a flame.
A UV detector for detecting the amount, an IR detector for detecting an IR amount due to CO ₂ resonance radiation peculiar to the flame, and UV and IR
A signal processing unit that converts a steady level in the installation environment of the radiation source into an ON / OFF signal and an adjustment signal that is equal to or higher than the steady level, and an ON / OFF signal output from each of the UV and IR signal processing units. An AND determination unit that inputs the logical product of both signals, a signal addition unit that adds adjustment signals output from the UV and IR signal processing units, and a signal output from the AND determination unit And a comparison / determination unit that outputs an activation signal when the addition signal output from the signal addition unit exceeds a predetermined level, and via an output unit when the activation signal from the comparison / determination unit continues for a certain period of time. And a timer unit for outputting a notification signal.

A UV detecting photoelectric tube is used as a UV detecting unit in the flame detecting device.
It is preferable to have a waveform shaping circuit that converts a discharge signal based on V into a pulse waveform signal.

Preferably, the IR detector in the flame detector uses an infrared sensor, and has a filter for selecting and amplifying a fluctuation frequency band and an AC amplifier circuit. .

Further, a thermocouple sensor is used as the IR in the flame detection device, and a direct current amplifying circuit for amplifying the direct infrared component detected by the thermocouple sensor is provided. It is preferable to provide a circuit.

[0011]

According to the present invention, the UV amount radiated from the flame generated by the fire and the IR amount due to the CO ₂ resonance radiation are simultaneously detected by the two detection units, and their detection signals are input to the signal processing unit. The signal is converted into a steady-state canceled ON / OFF signal in the installation environment and an adjustment signal at or above the steady level. These UV and I
The ON / OFF signal output from the R signal processing unit is AND
The logical product is obtained in the determination unit, and both output signals are O
When the signal is an N signal, a coincidence signal is output from the AND determination unit, and both adjustment signals are added in the signal addition unit, and the added signal is output. Then, when the coincidence signal is input to the comparison determination unit, and when the addition signal exceeds a predetermined level, an operation signal is output and input to the timer unit, and the operation signal continues for a predetermined time. Only when is the notification signal output.

As described above, since UV and IR are simultaneously detected and the flame is detected by comparing the sum of the converted signals with a predetermined level, the radiation is determined depending on the size of the flame and the type of combustible material causing the flame. No matter how the ratio between UV and IR changes, the flame can be detected reliably and quickly at the stage of a small flame, and at this time, ON which cancels the steady level in the installation environment
・ Since the logical product of the OFF signals is used as the judgment condition, it is possible to prevent malfunctions due to changes in the installation environment of the radiation source, and it is possible to cancel the transient signal with the timer unit. Accurate and quick flame detection can be performed without causing unreporting or the like throughout.

In this case, in particular, a UV detecting photoelectric tube is used as the UV detecting section, and the analog signal is converted into a pulse signal by a waveform shaping circuit using a UV shaping circuit. make it easier. Further, when the pyroelectric or thermocouple type sensor is used as the IR detection unit, and the filter includes an AC amplifier circuit and a filter for selecting and amplifying a fluctuation frequency band,
Despite the characteristic fluctuation called the respiratory action of the flame, which is a problem for small flames, a given IR detection can be ensured.

Further, a thermocouple-type sensor is used as the IR detection unit in the flame detection device.
In the case of a configuration including a DC amplification circuit for amplifying a DC infrared component detected by the thermocouple type sensor and a change amount detection circuit, a large flame is generated at the same time as ignition, and the IR increases rapidly other than fluctuation. Can be reliably detected, and by using the amount of change as a determination factor for flame detection, it is possible to contribute to shortening of the time required for flame detection.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a flame detection device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a more detailed configuration of the flame detection device shown in FIG.

As shown in FIG. 1, the flame detecting apparatus according to one embodiment of the present invention is roughly divided into a UV detecting section 1 for detecting a UV amount and an IR amount based on CO ₂ resonance radiation peculiar to the flame. An IR detector 2; signal processors 3 and 4 provided corresponding to the two detectors 1 and 2;
An AND determination unit 5 that calculates the logical product of the ON / OFF signals output from the signal processing units 3 and 4;
A signal adding unit 6 for adding the adjustment signal output from the control unit 4;
A comparison / determination unit 7 that outputs an activation signal when the coincidence signal is output from the AND determination unit 5 and the addition signal output from the signal addition unit 6 exceeds a predetermined level; When the activation signal output from the comparison / determination unit 7 continues for a certain period of time, the timer unit 8 that outputs an activation signal and an alarm device (not shown) are notified based on the input of the activation signal output from the timer unit 8. And an output unit 9 for outputting a signal.

The details of each component of the flame detection device having the above-described general configuration will be described with reference to FIG. 2. The UV detection unit 1 includes a UV detection photoelectric tube (hereinafter referred to as a UV sensor) 10. Used, and this UV sensor 10
As shown in FIG. 3B, a UV signal of 5 to 260 (nm) is detected, and a discharge signal based on a trigger signal supplied through the power supply circuit 11 and the high voltage generation circuit 12 is passed through the waveform shaping circuit 13. To a simple pulse signal. Here, as shown in FIG. 3A, the pulse interval is long when the amount of UV radiated from the flame, that is, the amount of UV is small, and the pulse interval is short when the amount is large.

[0018] The IR detector 2, a thermocouple type annexed the CO ₂ optical filter 15 (thermopile) sensor (hereinafter, referred to as IR sensor) 14 using, 4 by CO ₂ resonance radiation by the IR sensor 14. 1 to 4.5 (μ
m), the AC component (1 to 1) due to the fluctuation of the flame is detected by the temperature sensor 16 in order to detect the small flame together with the steady radiation level in which the error component due to the ambient temperature is compensated.
15 Hz) is selectively separated and amplified by the AC amplifier 18.
Here, a large flame may be generated at the same time as the ignition, and the IR other than the fluctuation may suddenly increase. Therefore, the DC IR component other than the fluctuation is amplified by the DC amplifier 17 and is constituted by the memory circuit 27 and the analog storage circuit. The amount of change per unit time at a steady level other than the fluctuation is detected, and when the amount of change is equal to or greater than a predetermined value, the signal is input to the signal adder 6.

The UV signal processing section 3 converts the pulse signal from the UV detection section 1 into an analog voltage by an FV
(Frequency-voltage) conversion circuit 20 and a voltage comparison circuit 21 which is compared with a preset threshold level SL1 for canceling a noise component in the converted analog voltage. When the above signal is input, the level is adjusted so as to match the IR side, an analog adjustment signal as shown in FIG. 3C is output, and the voltage comparison circuit 21 outputs the signal from FIG. An ON / OFF signal as shown in FIG.

The IR signal processing section 4 includes a rectifying / smoothing circuit 22 for converting an AC signal from the IR detecting section 2 into a rectified and smoothed DC (pulsating current) analog voltage, and a rectifying / smoothing circuit 22 in the converted DC analog voltage. A voltage comparing circuit 23 which is compared with a preset threshold level SL2 for canceling a noise component; and when a signal having a steady level or more including noise is input, the level is adjusted so as to match with the UV side. In addition to outputting the analog adjustment signal as shown in FIG. 3E, the voltage comparator 23 outputs an ON / OFF signal as shown in FIG.

The AND determination section 5 determines whether the UV and I
An ON / OFF signal output from the voltage comparison circuits 21 and 23 of the R signal processing units 3 and 4 is input, and an AND circuit 24 that takes a logical product of both ON / OFF signals and a logical sum of both ON / OFF signals are obtained. When both of the signals output from the voltage comparison circuits 21 and 23 of the UV and IR signal processing units 3 and 4 are ON signals,
A coincidence signal is output from the D circuit 24 and input to the comparison / determination unit 7, while only one of the signals output from the UV and IR signal processing units 3 and 4 is an ON signal. At one time, a mismatch signal is output from the OR circuit 25 and is input to the memory circuit 27 to set the memory circuit 27 in a reset state.

The signal adder 6 and the comparison determiner 7
It is configured integrally as an addition / judgment circuit 26, and adds analog adjustment signals as shown in FIGS. 3 (c) and 3 (e) output from the UV and IR signal processing units 3 and 4, respectively. An analog voltage addition signal as shown in FIG. 3 (g) is output, and this analog voltage addition signal exceeds a predetermined threshold level SL3 and a match is obtained from the AND circuit 24 of the AND determination section 5. When a signal is being input, an operation signal as shown in FIG.

The timer section 8 is composed of a timer circuit, and the operation signal from the addition / judgment circuit 26 (comparison / judgment section 7) is supplied for a predetermined time t as shown in FIG. When the operation is continued over, the ON signal is output to the output unit 9.
Is notified to an alarm device or the like (not shown) through the output terminal that constitutes (1).

Next, the operation of the flame detecting device configured as described above will be briefly described with reference to the flowchart shown in FIG. When a flame is generated due to the occurrence of a hydrocarbon fire, UV and IR are radiated from the flame in a spectral distribution as shown in FIG. 5, and the UV is incident on the UV sensor 10 and 4.1 to 4.1 due to CO ₂ resonance radiation. 4.5 (μ
IR having a peak level of m) is incident on the IR sensor 14 through the optical filter 15, and UV and IR are simultaneously detected (steps S1 and S2). U of them
V is passed through a waveform shaping circuit 13 and is converted into a pulse signal as shown in FIG. 3B, and is then input into an FV conversion circuit 20 to be converted into an analog voltage and matched with the IR side. And an analog adjustment signal x as shown in FIG. 3C is output (step S3).
~ S5).

In parallel with this, the IR detected by the IR sensor 14 includes an AC component (1 to 15 Hz) due to the fluctuation of the flame in order to detect the minute flame together with the steady radiation level whose ambient temperature is compensated by the temperature sensor 16. AC amplifier 1
After being amplified at 8, the signal is passed through a rectifying / smoothing circuit 22 to be rectified and smoothed, converted to a direct current (pulsating current) analog voltage, and level-adjusted to match the UV side. Is output (steps S6 to S8). Further, a DC IR component other than the fluctuation which rapidly increases due to a large flame at the time of ignition is amplified by the DC amplifier 17, and then input to the memory circuit 27 and the variation detection circuit 19 (steps S9 to S1).
0).

Next, the analog adjustment signals x and y
Are input to voltage comparison circuits 21 and 23, and are compared with respective thresholds S1 and S2 to output ON signals x1 and y1 when x exceeds S1 and when y exceeds S2, respectively. With those O
The N signals x1 and y1 are input to the AND circuit 24, and a logical AND of them is output to output a coincidence signal.
When the ON signal x1 or y1 is output from only one of the voltage comparison circuits 21 and 23, the OR circuit 25 takes a logical sum to output a mismatch signal, which is input to the memory circuit 27 and The DC IR component at that time is set in the memory circuit 27, and the amount of change between the set DC IR component and the DC IR component other than the fluctuation after ignition is detected by the change amount detecting circuit 19, and the change amount is detected. The signal z is output (Steps S11 to S15).

Next, as shown in FIG. 3C, an analog adjustment signal x output from the FV conversion circuit 20 and output from the rectification / smoothing circuit 22 are output as shown in FIG. The analog adjustment signal y and the change amount signal z are input to the addition / judgment circuit 26, and these signals x,
The signals y and z are added in the signal adder 6, and the comparison determiner 7 determines whether or not the analog voltage addition signal exceeds a predetermined threshold level SL3. An operation signal as shown in (h) of FIG. 3 is output, and is input to the timer unit 8 including a timer circuit. In the timer section 8, the addition / determination circuit 26 (comparison / determination section 7)
As shown in FIG. 3 (i), it is determined whether or not the operation signal output from the output terminal continues for a predetermined period of time t. ), An alarm device (not shown) is notified to activate the alarm device and output an alarm (step S16).
To S19).

As described above, UV and IR are detected at the same time, and the sum of the converted analog voltage signals x and y is compared with a predetermined threshold level SL3.
Since the flame is determined and output, no matter how the ratio of UV and IR emitted varies depending on the size of the flame and the type of combustible material that causes it, small flames that can cause fire of various combustible materials It is possible to reliably and quickly detect and output an alarm, and at this time, since the AND condition of the ON / OFF signal that has canceled the steady-state level in the installation environment is used as a judgment condition, the installation environment of the radiation source is determined. Since no malfunction occurs due to the change in the situation, and the temporary signal can be canceled by the timer section 8, a predetermined flame detection can be performed without causing a false alarm or the like over a general fire. Proper and quick.

In the structure of the above embodiment, UV,
The fire detection function can be further enhanced by adding a function of outputting a caution signal instead of an alarm output when each of the IR fluctuation and the IR steady radiation is independently detected.

[0030]

As described above, according to the present invention, UV and IR radiated from a flame are simultaneously detected, and the added value of the UV and IR and a predetermined level are determined by signal processing using a characteristic characteristic of the flame as a judgment condition. No matter how the ratio of UV and IR emitted varies depending on the size of the flame and the type of combustible material that causes it, the flame is detected at a small flame stage, and The flame can be detected quickly. In addition, since the AND condition of the ON / OFF signal that cancels the steady level in the installation environment is used as the judgment condition, occurrence of malfunction due to a change in the situation of the installation environment of the radiation source can be prevented, and the temporary signal is canceled by the timer unit. Therefore, it is possible to perform an accurate and prompt flame detection without being limited by a fire of a specific combustible material and without causing a false alarm over a general-purpose fire.

In addition, a high-sensitivity UV detection photoelectric tube is used as the UV detection unit, and the discharge signal due to UV is converted into a pulse waveform signal by a waveform shaping circuit. In addition, as described in claim 3, an infrared sensor is used as the IR detection unit, and a filter for selecting and amplifying a fluctuation frequency band and an AC amplifier circuit are provided. Even in the case of a small flame, a specific fluctuation called the respiratory action of the flame can be captured, and the predetermined IR detection can be reliably performed.

Furthermore, a DC amplifier circuit for amplifying a DC infrared component detected by the thermocouple sensor as an IR detection unit in the flame detection device, and a change circuit. In the case of a configuration having an amount detection circuit, a large flame can be detected at the same time as ignition, and the IR that rapidly increases in addition to fluctuation can be detected reliably, and the amount of change can be used as a judgment factor for flame detection. Utilization can contribute to shortening of the time required for flame detection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a flame detection device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a more detailed configuration of the flame detection device shown in FIG.

FIG. 3 is a signal waveform diagram of each part during a flame detection operation.

FIG. 4 is a flowchart illustrating a flame detection operation.

FIG. 5 is a characteristic diagram showing a flame spectrum curve in which the horizontal axis represents the wavelength of the radiated electromagnetic wave and the vertical axis represents the relative intensity.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 UV detection unit 2 IR detection unit 3, 4 signal processing unit 5 AND determination unit 6 signal addition unit 7 comparison determination unit 8 timer unit 9 output unit 10 UV sensor 13 waveform shaping circuit 14 IR sensor 15 optical filter 17 DC amplification circuit 18 AC amplification circuit 19 Change amount detection circuit 24 AND circuit 26 Addition / judgment circuit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Kobayashi Yamato Protec Co., Ltd. 2-1-1-10 Fukaekita, Higashinari-ku, Osaka-shi, Osaka (56) References JP-A-3-174699 (JP, A) JP-A-61-170895 (JP, A) JP-A-63-9969 (JP, A) JP-A-59-23888 (JP, U) JP-B-3-35720 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G08B 17/00-17/12 G01J 1/02 G01J 1/42

Claims (4)

(57) [Claims] 1. A flame detection device for detecting ultraviolet light and infrared light emitted from a flame, comprising: an ultraviolet light detection unit for detecting an amount of ultraviolet light; an infrared light detection unit for detecting an amount of infrared light due to CO ₂ resonance radiation peculiar to the flame; A signal processing unit that converts the steady-state level in the installation environment of the ultraviolet and infrared radiation sources into an ON / OFF signal and an adjustment signal that is higher than the steady level, and an ON / OFF signal output from each of the ultraviolet and infrared signal processing units An AND determination unit that receives an OFF signal and calculates a logical product of both signals; a signal addition unit that adds adjustment signals output from the ultraviolet and infrared signal processing units; and a signal output from the AND determination unit And an operation signal is output when an addition signal output from the signal addition section exceeds a predetermined level. Parts and, when the operating signal from the comparison determination unit has continued for a predetermined time, the flame detection device is characterized by comprising a timer unit for outputting a notification signal via the output unit. 2. The flame detecting device according to claim 1, wherein the ultraviolet ray detecting section uses an ultraviolet ray detecting photoelectric tube and has a waveform shaping circuit for converting a discharge signal due to the ultraviolet ray into a pulse waveform signal. 3. The flame detecting apparatus according to claim 1, wherein an infrared sensor is used as the infrared detecting section, and a filter for selecting and amplifying a fluctuation frequency band and an AC amplifying circuit are provided. 4. The infrared detector according to claim 1, wherein a thermocouple sensor is used as the infrared detector, and a DC amplifier circuit for amplifying a DC infrared component detected by the thermocouple sensor and a variation detection circuit are provided. Flame detector.