JP6755105B2 - Flame detector - Google Patents

Description

The present invention relates to a flame detector.

Conventionally, in an infrared flame detector (fire detector) having a function of automatically inspecting the degree of contamination of the windows constituting the housing, a light receiving element for detecting the degree of contamination is provided inside the housing window with inspection light. Each of the inspection light sources for irradiating the light is provided on the outside of the housing window (for example, Patent Documents 1 to 3). Then, the degree of contamination of the housing window was determined from the attenuation rate when the inspection light was incident on the light receiving element through the housing window. When this damping factor exceeds a predetermined threshold value (when the transmittance falls below a predetermined threshold value), a warning to that effect is output to the outside to encourage window cleaning and the detector. The protected area was kept safe.

Further, as a method for inspecting window stains by reflected light, a method has been devised in which stain detection of a vehicle headlamp is determined by the intensity of the amount of light received by a light receiving element provided inside the lamp (Patent Document 4).

Further, as for the window of the laser range finder, it is known that the reflected light of the housing window of the laser pulse light emitted from the inside of the housing is used for window dirt detection (Patent Documents 5 and 6).

Japanese Unexamined Patent Publication No. 2001-283345 JP-A-2002-109654 Japanese Unexamined Patent Publication No. 2005-121490 Jikkai Sho 57-184049 Japanese Unexamined Patent Publication No. 60-149984 Japanese Unexamined Patent Publication No. 8-327723

However, in the techniques described in Patent Documents 1 to 3, since the light source for checking the degree of contamination is provided outside the window of the housing, in a flame detector having a pressure-resistant explosion-proof housing, the light source for checking the degree of contamination can be used. , There are many restrictions to meet the criteria.

Further, the techniques described in Patent Documents 4 to 6 have a problem that a detection element for detecting stains needs to be separately provided.

The present invention has been made to solve the above problems, and it is possible to determine an abnormal state of a housing window or a detection element with a simple configuration without being restricted by satisfying the standard of a pressure-resistant explosion-proof structure. The purpose is to provide a flame detector that can be used.

In order to achieve the above object, the flame detector according to the present invention includes a detection element that detects infrared light incident from the outside and passes through a housing window and converts it into an electric signal, and the detection element. A flame detection determination unit that determines whether or not a flame has been detected based on the detected electric signal, and an area of the housing window that is installed inside the housing window and corresponds to a flame detection target range. The housing window is normal based on an inspection light source installed so as to irradiate a part or all of the light source and an electric signal detected by the detection element when emitting light from the inspection light source. It is composed of an abnormality determination unit that determines at least one of whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal.

According to the flame detector according to the present invention, the detection element detects infrared light incident from the outside and transmitted through the housing window and converts it into an electric signal. The flame detection determination unit determines whether or not a flame has been detected based on the electric signal detected by the detection element.

Further, when the abnormality determination unit emits light from a light source installed inside the housing window and installed so as to irradiate the area of the housing window corresponding to the flame detection target range with light. Based on the electric signal detected by the detection element, whether or not the housing window is normal, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal. At least one of them is judged.

In this way, the light source is installed inside the housing window and is installed so as to irradiate the area of the housing window corresponding to the flame detection target range with light, and the detection element is emitted when the light source emits light. At least whether or not the housing window is normal, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal, based on the electric signal detected by By determining one, it is possible to determine whether or not the housing window or the detection element is normal with a simple configuration without being restricted to satisfy the standard of the pressure-resistant explosion-proof structure.

In the flame detector according to the present invention, a fixing member formed of a heat insulating member or an endothermic member may be further provided between the light source and the detection element. This makes it possible to prevent the detection element from erroneously detecting the heat radiated from the light source.

The abnormality determination unit according to the present invention detects in advance an electric signal detected by the detection element when emitting light from the light source during normal operation and by the detection element when emitting light from the light source. By comparing with the obtained electric signal, whether or not the housing window is normal, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal or not. At least one can be determined.

Further, the abnormality determination unit according to the present invention includes a predetermined electric signal detected by the detection element when emitting light from the light source during normal operation and the detection element when emitting light from the light source. Whether the housing window is normal or not based on a value indicating a comparison result of comparison with the electric signal detected by the above and a predetermined threshold value for whether or not the housing window is normal. Whether or not, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal is determined, and a value indicating the comparison result and the said detection element are normal. It is possible to determine whether or not the detection element is normal based on a predetermined threshold value for whether or not the detection element is normal.

The abnormality determination unit according to the present invention determines whether or not the housing window is normal based on the electric signal detected by the detection element when the light source emits light a plurality of times, and the detection element is normal. At least one of whether or not the flame detection determination unit is normal and whether or not the determination by the flame detection determination unit is normal can be determined.

According to the flame detector of the present invention, the light source is installed inside the housing window and is installed so as to irradiate a part or all of the area of the housing window corresponding to the flame detection target range. Based on the electric signal detected by the detection element when emitting light from the light source, whether or not the housing window is normal, whether or not the detection element is normal, and the flame detection determination unit. Whether or not the housing window or the detection element is normal with a simple configuration without being restricted to satisfy the standard of the pressure-resistant explosion-proof structure by judging at least one of whether or not the judgment by The effect of being able to determine whether or not it is obtained can be obtained.

It is a block diagram which shows the structure of the flame detector which concerns on 1st Embodiment of this invention. It is a figure which shows the arrangement of a sensor and an inspection light source. It is a figure which shows the arrangement of a sensor, an inspection light source, and a fixing member. It is a graph which shows the thermal noise when the fixing member is not used. It is a graph which shows the thermal noise when the fixing member made of resin is used. It is a graph which shows the thermal noise when the fixing member made of aluminum is used. It is a top view which shows the example of the shape of the fixing member. It is a top view which shows the example of the shape of the fixing member. It is a top view which shows the example of the shape of the fixing member. It is a figure which shows the arrangement of a sensor and an inspection light source. It is a block diagram which shows the structure of the 1st arithmetic processing part and the 2nd arithmetic processing part of the flame detector which concerns on 1st Embodiment of this invention. (A) A diagram showing a state of inspection at the time of shipping inspection, (B) a diagram showing a state of inspection when an element is defective or a lamp is defective, and (C) a diagram showing a state of inspection when a window is dirty. .. (A) The figure which shows the sensor output at the time of a shipping inspection, (B) the figure which shows the sensor output at the time of element failure or a lamp failure, and (C) figure which shows the sensor output at the time of window dirt. It is a graph which shows the relationship between a sensitivity ratio and a transmittance. It is a flowchart which shows the abnormal state determination processing routine in the 1st arithmetic processing part and the 2nd arithmetic processing part of the flame detector which concerns on 1st Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Outline of Embodiment of the present invention>
If the sensor of the infrared flame detector is defective or the window is dirty, the flame detection function will be hindered. Therefore, in the embodiment of the present invention, if the sensitivity falls below a certain level, a warning or alarm to that effect is issued. By outputting to the outside, it encourages the inspection of the sensor and the cleaning of the window. This keeps the protective area of the detector safe.

Some of the automatic inspection functions of the flame detector are equipped with an automatic inspection function that outputs to the outside the occurrence of an event that interferes with the flame detection function, such as a defective element or a decrease in sensitivity due to window dirt.

In a flame detector whose housing has a pressure-resistant explosion-proof structure, when arranging an inspection light source outside, there are many restrictions to meet the standards for the pressure-resistant explosion-proof structure, and the amount of inspection light decreases due to window dirt on the light source itself. There was a problem. On the other hand, if the inspection light source is arranged inside, it is possible to detect window dirt without being subject to such restrictions, which can lead to simplification of housing design and mold design and price reduction.

In the present embodiment, since the inspection light source is arranged inside the window, in order to acquire the reflected light (initial reflected light) in a state where the window is clean, the position where the reflected light amount can be best taken is searched by an experiment and received. Place it near the element.

Further, a fixing member (aluminum attachment with counterbore holes) is provided for the purpose of fixing the position of the light source and spreading the light over a wide range so that the position of the inspection light source does not change. Various materials were examined for this fixing member in order to arrange the inspection light source near the infrared sensor and reduce the influence of thermal noise. As a result, it was found from experiments that a metal member as an endothermic member is more suitable than a foam-based heat insulating material having a high heat insulating effect.

In addition, the inspection light source blinks 5 times in 5 seconds, and the difference between the top value (average value) and the bottom value (average value) of the signal value is adopted as the signal value, so that the signal of the entire background is signaled during the inspection. The signal can be acquired accurately even if the amount changes.

<First Embodiment>
<System configuration>
Hereinafter, the flame detector according to the first embodiment of the present invention will be described.

As shown in FIG. 1, the flame detector 10 according to the first embodiment detects infrared light in a band near 4.5 μm of the carbon dioxide resonance radiation band generated by the flame through the housing window 40. One sensor 12, a second sensor 14 that detects infrared light in a band near 4.0 μm in a band shorter than the carbon dioxide resonance radiation band through the housing window 40, and 5.0 μm in a band longer than the carbon dioxide resonance radiation band. The third sensor 16 that detects infrared light in a nearby band through the housing window 40, the first amplification unit 18 that amplifies the signal from the first sensor 12, and the signal from the second sensor 14 are amplified. The second amplification unit 20, the third amplification unit 22 that amplifies the signal from the third sensor 16, the amplification unit that amplifies the signals from the first amplification unit 18, the second amplification unit 20, and the third amplification unit 22. 24, an AD conversion unit 26 that converts a signal from the amplification unit 24 into a digital value, a first arithmetic processing unit 28 that controls preprocessing for flame detection and an alarm unit 32, and a processing for detecting a flame. It includes a second arithmetic processing unit 30, an alarm unit 32, and an inspection light source 34.

The first sensor 12 detects the infrared light transmitted through the filter 12A and the filter 12A that transmits infrared light in the band near 4.5 μm of the carbon dioxide resonance radiation band emitted by the flame, and converts the infrared light into an electric signal of a DC component. The detection element 12B is provided.

The second sensor 14 detects infrared light transmitted through the filter 14A and a filter 14A that transmits infrared light in a band near 4.0 μm, which is shorter than the carbon dioxide resonance radiation band, and converts it into an electric signal of a DC component. The detection element 14B is provided.

The third sensor 16 detects infrared light transmitted through the filter 16A and a filter 16A that transmits infrared light in a band in the vicinity of 5.0 μm, which is longer than the carbon dioxide resonance radiation band, and converts the infrared light into an electric signal of a DC component. The detection element 16B is provided.

In addition, the same sensor as the first sensor 12 may be further provided in order to reliably capture a weak electric signal for detecting infrared light in a band near 4.5 μm of the carbon dioxide resonance radiation band.

The detection elements 12B, 14B, 16B are made of a thermopile.

The first amplification units 18, 20, and 22 independently amplify the electric signals of the first sensor 12, the second sensor 14, and the third sensor 16, respectively.

The amplification unit 24 includes a switch unit (not shown) that sequentially switches the electric signals individually amplified by the first amplification units 18, 20, and 22 into one electric signal at a fixed time. The electric signal aggregated by the above is selectively amplified (high gain when the signal is small, low gain when the signal is large) according to the strength of the electric signal.

The inspection light source 34 is provided inside the housing window 40 together with the first sensor 12, the second sensor 14, and the third sensor 16.

The inspection light source 34 emits light including an infrared region and is strong enough to obtain a reflected light signal even in a clean housing window 40 (a state in which the reflected light is extremely small). Further, as shown in FIG. 2, the inspection light source 34 emits light in a wide-angle direction so as to obtain reflection / scattering in a wide range as much as possible.

Further, as shown in FIG. 3, the positional relationship between the inspection light source 34, the housing window 40, the first sensor 12, the second sensor 14, and the third sensor 16 is related to the surface of the housing window 40 (outside the housing). The area of the field of view (flame detection target range) of each sensor is included in the light radiation range of the inspection light source 34, or has a positional relationship that overlaps with the light radiation range of the inspection light source 34, and the light of the inspection light source 34. Is in a positional relationship in which light does not directly enter the detection elements 12B, 14B, 16B of each sensor.

However, since each sensor has high sensitivity, even if the inspection light is applied to other than the detection element of the sensor, it is regarded as thermal noise. Therefore, the inspection light source 34, the first sensor 12, the second sensor 14, and the inspection light source 34, and A fixing member 42 formed of a heat absorbing member (for example, made of aluminum) is provided between the third sensor 16 and the inspection light source 34, the first sensor 12, the second sensor 14, and the fixing member 42. And each of the third sensor 16 is fixed. The fixing member 42 has not only a radiant heat shielding function but also a function as a reflector for inspection light.

The fixing member 42 may be a member other than aluminum as long as it has good heat transfer (well absorbs heat). On the other hand, a member having an excellent heat insulating effect (foamed resin, rubber, paper, etc.) may be used. As shown in FIGS. 4 to 6, in the experiment, the aluminum member (heat absorption effect) had a better S / N ratio. Therefore, in the present embodiment, the aluminum fixing member 42 is used.

Further, as the shape of the fixing member 42, for example, some shapes as shown in FIG. 7 can be considered. Further, as shown in FIG. 8, a plurality of inspection light sources 34 may be arranged as needed. When there are two sensors, the shape of the fixing member 42 may be as shown in FIG. 9A. In this case, as shown in FIG. 9B, the inspection light source 34 has a part or all of the field of view range (flame detection target range) of each sensor on the surface (outside of the housing) of the housing window 40. It is arranged so as to be within the light radiation range of.

The first arithmetic processing unit 28 and the second arithmetic processing unit 30 are each composed of a CPU, and the functions of the first arithmetic processing unit 28 and the second arithmetic processing unit 30 are divided for each function realizing means. Explaining in terms of blocks, as shown in FIG. 10, the first arithmetic processing unit 28 includes a signal acquisition unit 44, a correction coefficient setting unit 46, a correction unit 48, a light source control unit 50, and an alarm control unit 52. .. Further, the second arithmetic processing unit 30 includes a fire determination unit 54, a number of times determination unit 56, and an abnormality determination unit 60.

From the signal output from the AD conversion unit 26, the signal acquisition unit 44 obtains the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16. get.

The correction coefficient setting unit 46 receives a signal acquisition unit 44 when the first sensor 12, the second sensor 14, and the third sensor 16 are irradiated with the reference light of infrared light from a reference light source such as a blackbody furnace. Based on each value of the electric signal acquired by, a correction coefficient for correcting the variation is set in advance.

The correction unit 48 refers to the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 acquired by the signal acquisition unit 44. , Correction is performed using the correction coefficient set by the correction coefficient setting unit 46, and is output to the second arithmetic processing unit 30.

The light source control unit 50 controls the inspection light source 34 to blink a plurality of times when determining window contamination.

Here, the principle of determining window dirt will be described.

Since the automatic inspection function of the present embodiment uses an extremely sensitive infrared sensor for the optical unit, individual differences (variations in performance) of the sensor itself and the inspection light source also affect the inspection function. Therefore, the initial value (initial value of the light source) detected by each sensor when the inspection light of the inspection light source 34 is irradiated in the initial state (for example, at the time of shipment from the factory) without window stains is measured, and the value is measured. Is stored in the storage area in the flame detector 10, and by comparing the initial value of the light source with the current value at the time of inspection, the dirt on the window, each sensor, the flame detection determination unit, and / or the determination by the flame detection determination unit Is normal or not (see FIG. 11).

It is necessary to set a threshold value to output a window stain alarm or an abnormality alarm according to the degree of window contamination, but the threshold value has some stains on the reflectance of the inspection light and the transmittance of the reference light. Measure in advance with a window, and derive the correlation formula to determine. That is, the threshold is determined to issue an alarm when it falls below an arbitrary transmittance (see FIG. 12).

Regarding window stains, the color of stains, the form of stains (liquid / solid), the shape of stain particles (spherical / non-spherical), the particle diameter or droplet diameter of stains (particle size distribution), and the unit area of the stain surface Classification is performed according to conditions such as the number of hit particles and the reflectance of dirty particles, and a correlation formula is derived from the transmittance under each condition to determine the threshold value (see FIG. 13). However, when determining the threshold value, it is not necessary to reflect all the above-mentioned stain conditions, and one or a plurality of the above-mentioned stain conditions may be selected and the threshold value may be determined depending on the monitoring environment.

In addition, the accuracy of the inspection is improved by turning on the inspection light source 34 a plurality of times in one inspection and determining the window dirt by the average.

According to the principle described above, in the present embodiment, the abnormality determination unit 60 has the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the electric signal from the third sensor 16. For each of the values of, the difference between the top value (average value) and the bottom value (average value) of the corrected values when the inspection light source 34 blinks 5 times in 5 seconds is calculated as the light source check value. By comparing with the initial value of the light source in the initial state obtained in advance, the housing window 40, the first sensor 12, the second sensor 14, the third sensor 16, the first amplification unit 18, the second amplification unit 20, and the second 3 It is determined whether or not the amplification unit 22, the amplification unit 24, the AD conversion unit 26, the inspection light source 34, the first arithmetic processing unit 28, and / or the second arithmetic processing unit 30 are normal.

Specifically, when the sensitivity ratio shown in the following formula is calculated and compared with the window stain warning threshold value, the abnormality warning threshold value, and the sensor failure / light source failure threshold value, when the predetermined conditions are satisfied, the housing Body window 40, 1st sensor 12, 2nd sensor 14, 3rd sensor 16, 1st amplification unit 18, 2nd amplification unit 20, 3rd amplification unit 22, amplification unit 24, AD conversion unit 26, inspection light source 34, It is determined that the first arithmetic processing unit 28 and / or the second arithmetic processing unit 30 is in an abnormal state.

In the present embodiment, when the sensitivity ratio is equal to or higher than the window stain alarm threshold value or equal to or higher than the abnormal alarm threshold value, it is determined that the housing window 40 is in an abnormal state due to window stain. When the sensitivity ratio is equal to or lower than the sensor failure / light source failure threshold value, the first sensor 12, the second sensor 14, the third sensor 16, the first amplification unit 18, the second amplification unit 20, and the third amplification unit 22 , The amplification unit 24, the AD conversion unit 26, or the inspection light source 34 is determined to be in an abnormal state. In particular, when there is no electric signal from the first sensor 12, the second sensor 14, and the third sensor 16, it is determined that the inspection light source 34 is in the “lamp out” state.

In the fire determination unit 54, the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 corrected by the correction unit 48 are equal to or higher than the threshold value E. And, the calculated value of the electric signal from the first sensor 12 obtained from the approximate straight line of the value of the electric signal from the second sensor 14 and the value of the electric signal from the third sensor 16 is compared with the threshold value A. It is determined that the flame is detected when the result of the above satisfies the predetermined conditions.

The determination by the fire determination unit 54 is repeatedly executed at regular intervals.

The number-of-times determination unit 56 determines that the number of times the fire determination unit 54 has determined that the flame has been continuously detected is equal to or greater than a predetermined number of consecutive times, or that the fire determination unit 54 has detected the flame within a certain period of time. A fire signal is output when the number of times has been set is equal to or greater than a predetermined cumulative number of times.

The alarm control unit 52 controls the alarm unit 32 so as to notify the abnormal state when the abnormality determination unit 60 determines that the abnormal state is present. Further, the alarm control unit 52 controls the alarm unit 32 so as to notify a fire when a fire signal is output from the number of times determination unit 56. For example, the alarm lamp constituting the alarm unit 32 is turned on.

<Action of flame detector>
Next, the operation of the flame detector 10 according to the first embodiment will be described.

First, the initial value of the light source is set in advance for the flame detector 10 before installation. Specifically, the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 in a state where the housing window 40 is clean. For each of the above, the difference between the top value (average value) and the bottom value (average value) of the corrected values when the inspection light source 34 blinks 5 times in 5 seconds is calculated as the light source initial value, and the first The initial light source values are set for the sensor 12, the second sensor 14, and the third sensor 16.

The flame detector 10 in which the initial value of the light source is set is installed at a place where the fire judgment should be performed, and an electric signal is output from each of the first sensor 12, the second sensor 14, and the third sensor 16 of the flame detector 10. When the value of each signal is input to the first arithmetic processing unit 28 via the first amplification unit 18, the second amplification unit 20, the third amplification unit 22, the amplification unit 24, and the AD conversion unit 26. In addition, the first arithmetic processing unit 28 and the second arithmetic processing unit 30 of the flame detector 10 repeatedly execute the fire determination process to determine whether or not a flame has been detected.

Further, the first arithmetic processing unit 28 and the second arithmetic processing unit 30 of the flame detector 10 execute the abnormal state determination processing routine shown in FIG. 14 at regular intervals.

In step 100, the light source control unit 50 starts irradiating the light from the inspection light source 34 and controls the inspection light source 34 so as to blink 5 times in 5 seconds, for example.

Then, in step 102, while irradiating light from the inspection light source 34, the signal acquisition unit 44 receives the value of the electric signal from the first sensor 12 and the second sensor 14 from the signal output from the AD conversion unit 26. The value of the electric signal from the third sensor 16 and the value of the electric signal from the third sensor 16 are acquired.

In step 104, the light source control unit 50 ends the irradiation of light from the inspection light source 34 when the inspection light source 34 has finished blinking five times.

In the next step 106, the correction unit 48 sets the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 acquired in step 102. On the other hand, correction is performed using a preset correction coefficient.

Then, in step 108, the abnormality determination unit 60 refers to each of the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16. The difference between the top value (average value) and the bottom value (average value) of the values corrected in step 106 is calculated as the light source check value.

In the next step 110, the abnormality determination unit 60 refers to each of the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16. The sensitivity ratio is calculated based on the light source check value calculated in step 108 and the light source initial value obtained in advance.

Then, in step 112, the abnormality determination unit 60 refers to each of the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16. By comparing the sensitivity ratio calculated in step 110 with the window dirt alarm threshold, the abnormality alarm threshold, and the sensor failure / light source failure threshold, the housing window 40, the first sensor 12, the second sensor 14, and the third sensor are compared. 16. It is determined whether or not the first amplification unit 18, the second amplification unit 20, the third amplification unit 22, the amplification unit 24, the AD conversion unit 26, and the inspection light source 34 are normal.

For example, the sensitivity ratio calculated for at least one of the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 is a window stain. When it is equal to or higher than the alarm threshold value or the abnormal alarm threshold value, it is determined that the housing window 40 is in an abnormal state due to window dirt.

Further, the sensitivity ratio calculated for at least one of the value of the electric signal from the first sensor 12, the value of the electric signal from the second sensor 14, and the value of the electric signal from the third sensor 16 is a sensor defect. -If the signal is below the defective light source threshold, the first sensor 12, the second sensor 14, the third sensor 16, the first amplification unit 18, the second amplification unit 20, the third amplification unit 22, the amplification unit 24, and AD conversion. It is determined that the unit 26 or the inspection light source 34 is in an abnormal state.

In step 114, it is determined in step 112 whether or not it is determined to be in an abnormal state, and if it is determined to be in an abnormal state, in step 116, the alarm control unit 52 issues an abnormal signal to the alarm unit. Outputs to 32 and ends the abnormal state determination processing routine. On the other hand, if it is not determined to be in an abnormal state, the abnormal state determination processing routine is terminated as it is, and it is determined that the fire determination is normally performed.

As described above, according to the flame detector according to the first embodiment, the inspection light source is installed inside the housing window, and light is applied to the area of the housing window corresponding to the flame detection target range. A pressure-resistant explosion-proof structure by determining whether or not the housing window or sensor is normal based on the electrical signal detected by each sensor when the light is emitted from the inspection light source. With a simple configuration, it is possible to determine whether or not the determination by the housing window, each sensor, the flame detection determination unit, and / or the flame detection determination unit is normal, without being restricted to satisfy the criteria of.

In addition, by arranging the inspection light source inside the housing window, the inspection light source itself is not contaminated, and the housing window, each sensor, and flame detection are not restricted to meet the standards of the pressure-resistant explosion-proof structure. It is possible to determine whether or not the determination by the determination unit and / or the flame detection determination unit is normal.

In addition, since the infrared sensor used in the flame detector has high sensitivity, a high-sensitivity sensor for capturing the reflected light of the inspection light source should be separately provided by using the infrared sensor itself for the inspection function. Is unnecessary.

In addition, since the infrared sensor has high sensitivity, the power consumption of the inspection light source can be suppressed to about 0.3 W, and the automatic flame detector that does not have a high-intensity high-energy light source such as a vehicle headlamp or laser light The inspection was made possible.

Further, the accuracy of the inspection can be improved by turning on the inspection light source a plurality of times in one inspection and determining the window dirt by the average value of the detected values.

In addition, the soundness of the flame detector can be maintained, and the safety of the protection zone of the flame detector can be further enhanced. In addition, since the inspection timing is transmitted from the device side, it becomes possible to predict the inspection cycle and the like in the same installation environment, and efficient inspection is achieved.

Further, by reducing the power consumption of the inspection light source, the power consumption of the detector can be suppressed. Therefore, for example, when a plurality of flame detectors are simultaneously inspected by an external trigger, the burden on the power supply side can be reduced.

<Second Embodiment>
Next, the flame detector according to the second embodiment will be described. Since the configuration of the flame detector according to the second embodiment has the same configuration as that of the first embodiment, the same reference numerals are given and the description thereof will be omitted.

The second embodiment is different from the first embodiment in that a plurality of first sensors 12 for detecting infrared light in a band in the vicinity of 4.5 μm of the carbon dioxide resonance radiation band are provided. In the present embodiment, a case where the flame detector according to the second embodiment includes two first sensors 12, a second sensor 14, and a third sensor 16 will be described as an example.

In the second embodiment, when the abnormality determination unit 60 loses the balance of the sensitivity ratio calculated for each of the two first sensors 12, it is in an abnormal state due to the failure of the first sensor 12. Judge that there is. For example, the sensitivity ratios calculated for each of the two first sensors 12 are compared, and if there is a bias, it is determined that the state is abnormal due to the failure of the first sensor 12.

Since other configurations and operations of the flame detector according to the second embodiment are the same as those of the first embodiment, the description thereof will be omitted.

In this way, the abnormal state due to the failure of the first sensor 12 can be determined based on the balance of the sensitivity ratio calculated for each of the two first sensors 12.

The present invention is not limited to the above-described embodiment, and various modifications and applications are possible without departing from the gist of the present invention.

For example, the case where three sensors that detect infrared light are used to detect a flame has been described as an example, but the present invention is not limited to this, and one that detects infrared light to detect a flame is used. The above sensor may be used. In this case, the one or more sensors may be used to determine whether or not the determination by the housing window, each sensor, the flame detection determination unit, and / or the flame detection determination unit is normal.

Further, the case where a member formed of a heat absorbing member such as aluminum is used as the fixing member has been described as an example, but the present invention is not limited to this, and a fixing member formed of a heat insulating member such as a foam type is used. You may.

10 Flame detector 12 1st sensor 12A, 14A, 16A Filter 12B, 14B, 16B Detection element 14 2nd sensor 16 3rd sensor 28 1st arithmetic processing unit 30 2nd arithmetic processing unit 32 Alarm unit 34 Inspection light source 40 Housing window 42 Fixing member 44 Signal acquisition unit 50 Light source control unit 52 Alarm control unit 54 Fire judgment unit 60 Abnormality judgment unit

Claims (4)

A group of detection elements including detection elements that detect infrared light incident from the outside and pass through the housing window and convert it into an electric signal, and the infrared light in the carbon dioxide resonance radiation band emitted by the flame is described above. A first detection element that detects through the housing window, a second detection element that detects infrared light in a band shorter than the carbon dioxide resonance radiation band through the housing window, and a band longer than the carbon dioxide resonance radiation band. A group of detection elements including a third detection element that detects infrared light of the above through the housing window, and
Whether or not a flame is detected is determined based on the electric signal detected by the first detection element, the electric signal detected by the second detection element, and the electric signal detected by the third detection element. Flame detection judgment unit to judge and
A light source installed inside the housing window and installed so as to irradiate a part or all of the region of the housing window corresponding to the flame detection target range with light including an infrared region.
Based on the electric signal detected by the first detection element while emitting light from the light source, the electric signal detected by the second detection element, and the electric signal detected by the third detection element. , An abnormality determination unit that determines at least one of whether or not the housing window is normal, whether or not the detection element group is normal, and whether or not the determination by the flame detection determination unit is normal. When,
A fixing member made of aluminum provided between the light source and the detection element group so as to shield radiant heat from the light source to the detection element group, and the light source and the detection element group. A fixing member for fixing the group and
Flame detector including. The abnormality determination unit includes a predetermined electric signal detected by the first detection element when light is emitted from the light source in a normal state, an electric signal detected by the second detection element, and the third. The electric signal detected by the detection element, the electric signal detected by the first detection element when emitting light from the light source, the electric signal detected by the second detection element, and the third detection element. By comparing with the detected electric signal, whether or not the housing window is normal, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal or not. The flame detector according to claim 1, wherein at least one of the above is determined. The abnormality determination unit uses the first detection element to generate an electric signal detected by the first detection element when it is emitting light from the light source when it is emitting light from the light source when it is normally obtained. Sensitivity ratio obtained by dividing by the detected electrical signal,
The electric signal detected by the first detection element when emitting light from the light source is a previously obtained electric signal detected by the first detection element when emitting light from the light source during normal operation. The sensitivity ratio obtained by division and the electric signal detected by the first detection element when emitting light from the light source are obtained in advance, and when emitting light from the light source during normal operation, the first When at least one of the sensitivity ratios obtained by dividing by the electric signal detected by the detection element is equal to or more than a predetermined threshold value for whether or not the housing window is normal, the housing window is Judging that it is not normal,
Obtained for the sensitivity ratio obtained for the electric signal detected by the first detection element, the sensitivity ratio obtained for the electric signal detected by the second detection element, and the electric signal detected by the third detection element. The flame detector according to claim 2, wherein when at least one of the sensitivity ratios is equal to or less than a predetermined threshold value for whether or not the detection element is normal, it is determined that the detection element is not normal. The abnormality determination unit is detected by the electric signal detected by the first detection element, the electric signal detected by the second detection element, and the third detection element when light is emitted from the light source a plurality of times. At least one of whether or not the housing window is normal, whether or not the detection element is normal, and whether or not the determination by the flame detection determination unit is normal is determined based on the electric signal. The flame detector according to any one of claims 1 to 3.