JP2019191902A - Flame detection device - Google Patents

Abstract

To provide a flame detection device capable of reducing time required for a dirtiness test of translucent windows by driving two test light sources.SOLUTION: A flame detection device 10 is equipped with two flame detection units configured to observe radiation energy emitted from burning flame using photosensitive elements to determine the presence/absence of and detect burning flame. A sensor storage part disposed on a front side of a housing has a central protrusion 54 provided between a pair of translucent windows 18-1, 18-2 for radiation energy to enter and reach each of the photosensitive elements of the flame detection units. The central protrusion 54 has test windows 56-1, 56-2 provided on each side thereof and accommodates test light sources 60-1, 60-2 therein. A test controller alternately pulse-drives the test light sources 60-1, 60-2 such that one is not emitting light while the other is emitting light in order to irradiate flame detection sensors 16a, 16b and a non-flame detection sensor 16c with test light through the translucent windows 18-1, 18-2, detects a light reduction rate indicative of a degree of dirtiness, and outputs a dirt alarm signal to outside when the light reduction rate exceeds a predetermined threshold.SELECTED DRAWING: Figure 3

Description

The present invention relates to a flame detection device that detects infrared radiation generated by CO ₂ resonance during flammable combustion to determine the presence or absence of a flame.

Conventionally, in a flame detection device that detects infrared energy generated by flammable combustion and detects the presence or absence of flame, the infrared intensity in the resonance emission wavelength band of CO ₂ generated during flammable combustion is detected, Flame detection devices and flame detection methods for detecting the presence or absence of a flame are well known.

  Here, the conventional two-wavelength flame detection apparatus will be briefly described. FIG. 15 is a conceptual diagram showing an infrared spectrum in the infrared wavelength region of a combustion flame and other typical radiators, where the horizontal axis indicates the wavelength of infrared rays and the vertical axis indicates the relative intensity of infrared rays.

As shown in FIG. 15, in the spectral characteristic 100 of the combustion flame, there is a peak of the infrared relative intensity accompanying the resonance emission of CO _{2 in} the wavelength band near 5 μm, and there is a characteristic that exists in the vicinity of this peak wavelength. As the wavelength, for example, a wavelength band having a low infrared relative intensity exists in the vicinity of 5.0 μm on the long wavelength side. Hereinafter, unless otherwise specified, the CO ₂ resonance radiation band refers to the 4.5 μm band.

  In a two-wavelength flame detection device, for example, each infrared energy in a wavelength band near 4.5 μm and a wavelength band near 5.0 μm is selectively transmitted by a narrow band optical wavelength bandpass filter, The infrared energy is detected by a detection sensor, subjected to photoelectric conversion, and subjected to predetermined processing such as amplification to obtain an electrical signal corresponding to the amount of energy (hereinafter referred to as “light reception signal”), and each wavelength band The presence / absence of a flame is determined by taking the relative ratio of the received light signal level and comparing it with a predetermined threshold.

  Thereby, an infrared radiator other than a flame, for example, a high-temperature radiator such as sunlight shown in the spectral characteristic 102, a relatively low-temperature radiator shown in the spectral characteristic 104, or a low-temperature radiator such as a human body shown in the spectral characteristic 106 Etc. can be distinguished from flames.

  In addition, the flame detection device detects infrared energy generated by flammable combustion through a translucent window and monitors the presence or absence of a flame, and in order to maintain the flame monitoring function, As a self-test for monitoring dirt, a dirt test is conducted.

  In the dirt test, when a test signal periodically transmitted from the fire receiving panel is received, test light that becomes flame simulated light is incident on the translucent window from a test light source provided outside the flame detector, The detection unit receives the light and compares the received light signal with the unclean initial state to determine the light attenuation rate.If the light attenuation rate exceeds the specified contamination threshold, a contamination alarm signal is sent to the fire reception panel. Sending and outputting a dirt alarm.

  FIG. 16 is an explanatory view showing the appearance of a conventional flame detection device, FIG. 16 (A) is a view looking down from an oblique upper side, and FIG. 16 (B) is a view looking up from an oblique lower side.

  As shown in FIG. 16, the flame detection device 120 uses a cover provided on the front surface of the case body 122 as a sensor storage portion, and the sensor storage portion 124 is provided with a pair of left and right translucent windows 126. For each of the windows 126, a detector for receiving infrared energy generated by the flammable combustion is disposed. In addition, a test light source unit is provided in which a convex portion 128 is formed on the upper side in the vicinity of the translucent window 126 and the test light source is accommodated at a position where the detection sensor in the translucent window 126 below the convex portion 128 can be seen. The transparent test window 130 is provided here. Such test light source sections are individually provided corresponding to the left and right sides.

  When the test signal is received from the fire receiving board and the stain test of the translucent window 126 is performed, the test light is driven at a predetermined frequency for a predetermined time, for example, 2 seconds, to test the test light. Irradiate the corresponding translucent window 126 from the window 130, receive light by the detection unit, compare the light reception level with the light reception level in the initial state without contamination, determine the degree of contamination, determine the degree of contamination, Subsequently, the test light source of the other test window 130 is similarly driven at a predetermined frequency for 2 seconds to irradiate the test light with the corresponding translucent window 126 from the test window 130, and the detection unit receives the light. The level of contamination is determined by comparing the level with the received light level in the initial state without contamination to determine the light attenuation rate.

Japanese Patent No. 4404329 Japanese Patent No. 4817285 Japanese Patent No. 3357330 JP 2002-42263 A Japanese Patent No. 4623608

  However, the driving of the test light source by such a conventional stain test drives the two sets of test light sources in order, so that the time required for the stain test of the flame detection device becomes long. Since the flame detector performs the stain test of a plurality of flame detectors in order according to the test signal from the fire receiving board, the total time until the stain test of a large number of flame detectors is completed becomes longer, and the stain test is performed. During the operation, the fire reception board increases the control burden by performing the dirt monitoring control in addition to the normal fire monitoring control, which may adversely affect the processing performance in the event of a fire. is there.

  It is an object of the present invention to provide a flame detection apparatus that can shorten the test time by devising the driving of a test light source that performs a stain test on a translucent window.

(Flame detection device)
The present invention is a flame detection apparatus provided with two sets of flame detectors for observing the radiation energy radiated from a combustion flame with a detection sensor through a translucent window and determining the presence or absence of the combustion flame. There,
A central projection provided between the translucent windows disposed on the front surface of the housing;
A pair of test light sources that irradiate each of the detection sensors from the test windows disposed on both sides of the central convex portion through the translucent window;
A test control unit that alternately pulses to stop the light emission of one of the pair of test light sources while stopping the light emission of the other;
Is provided.

(Test using a common test light source)
In addition, the present invention provides a flame detection system provided with two sets of flame detectors that detect and detect the presence or absence of a combustion flame by observing the radiation energy emitted from the combustion flame with a detection sensor through a translucent window. A device,
A central projection provided between the translucent windows disposed on the front surface of the housing;
One test light source for irradiating each of the light receiving elements from a test window disposed on both sides of the central convex portion through a light-transmitting window;
Is provided,
The test light from one test light source is detected for the same period by each of the detection sensors of the two sets of detection units, and self-diagnosis is performed based on the detected test light quantity.

(Basic effect)
The present invention is a flame detection apparatus provided with two sets of flame detection units for observing the radiation energy radiated from a combustion flame with a detection sensor through a translucent window and determining the presence or absence of the combustion flame. A test is performed on each of the detection sensors from the central convex portion provided between the translucent windows arranged on the front surface of the housing and the test windows arranged on both sides of the central convex portion through the translucent windows. Since a pair of test light sources for irradiating light and a test control unit that alternately pulse-drives so as to stop the other light emission while emitting one of the pair of test light sources, The restriction is reduced, and the arrangement structure of the test light source and the test window with respect to the central convex portion can be simplified.

  In addition, by alternately pulsing two sets of test light sources so as to stop the emission of the other light when one of the light sources emits light, it is equivalent to the conventional case where a single test light source is pulse-driven. The drive time can be reduced to half, and the total test time until the completion of the soil test of a large number of flame detectors in accordance with the instructions from the fire receiver is significantly shortened. Time required for control can be reduced to the minimum necessary.

(Effects of testing with a common test light source)
The present invention is a flame detection apparatus provided with two sets of flame detectors for observing the radiation energy radiated from a combustion flame with a detection sensor through a translucent window and determining the presence or absence of the combustion flame. A central projection provided between the translucent windows disposed on the front surface of the housing;
One test light source that irradiates each of the light receiving elements with a test light from a test window disposed on both sides of the central convex portion through a translucent window is provided, and the test light from one test light source, Each of the detection sensors of the two sets of detection units detects the synchronization period, and performs self-diagnosis based on the detected test light quantity. As a result, the test light source is shared by the two sets of detection units. Therefore, when the test light source is driven, the test light amount is detected at the same time by the two sets of detection units. Accordingly, it is not necessary to test by sequentially or alternately driving a plurality of test light sources, and the test period can be shortened. In addition, current consumption for driving the test light source can be reduced.

The block diagram which showed embodiment of the flame detection part integrated in a flame detection apparatus Explanatory drawing showing the appearance of the flame detector Explanatory drawing which showed the flame detection apparatus of FIG. 2 from the front Explanatory drawing which showed in part the test light source arrange | positioned at the center convex part seeing the flame detection apparatus of FIG. 2 from the lower side, and the flame detection part arrange | positioned inside a test window and a translucent window Explanatory drawing which showed the detection unit assembled in the flame detection apparatus of FIG. 1 in the assembly / disassembly state Explanatory drawing showing the structure of the flame detection sensor Circuit diagram showing an equivalent circuit of the flame detection sensor of FIG. The characteristic view which showed the infrared transmittance in each wavelength of the optical wavelength filter applied to embodiment of FIG. 1, and a translucent window A signal waveform diagram showing a flame light reception signal output from the flame detection unit of FIG. 1 when infrared energy emitted from the combustion flame is observed. Explanatory drawing which showed frequency distribution of the flame light reception signal E3 obtained from the flame detection part of FIG. 1 when the infrared rays radiated | emitted from a combustion flame are observed Time chart showing drive signals for pulse driving test light source Explanatory drawing showing an embodiment of a flame detection device sharing a test light source from the front Explanatory drawing which showed in part the test light source arrange | positioned at the center convex part seeing the flame detection apparatus of FIG. 12 from the lower side, and the flame detection part arrange | positioned inside a test window and a translucent window FIG. 12 is a time chart showing drive signals for driving the test light source of FIG. Characteristic diagram showing infrared spectrum of combustion flame and other typical radiators Explanatory drawing showing the appearance of a conventional flame detector

[Flame detection device]
(Device overview)
FIG. 1 is a block diagram showing an embodiment of a flame detection unit incorporated in a flame detection apparatus, taking a two-wavelength flame detection apparatus as an example. It is assumed that the flame detection device of the present embodiment is a fire detection device that detects the presence or absence of a flame in the monitoring area.

  As shown in FIG. 1, the detection unit of the flame detection device 10 according to the present embodiment includes two sets of a flame detection unit 11-1 and another flame detection unit 11-2 (not shown) having the same configuration. Yes.

  The flame detection unit 11-1 includes a flame detection unit 12a, 12b, a non-flame detection unit 12c, and a determination unit 36 and a test control unit 38 provided in the MPU (microprocessor unit) 15.

The flame detection units 12a and 12b are for observing infrared energy radiated from the combustion flame existing in the monitoring area, and have a predetermined wavelength centered at 4.5 μm radiated from the combustion flame along with CO ₂ resonance. The infrared ray in the band is received and photoelectrically converted, and flame received light signals E1 and E2 are output.

  The flame detection units 12a and 12b are provided with an infrared transparent window 18 using sapphire glass or the like, flame detection sensors 16a and 16b, pre-filters 24a and 24b, preamplifiers 26a and 26b, and main amplifiers 28a and 28b. The flame light reception signals E1 and E2 output from the main amplifiers 28a and 28b are further amplified by the final stage amplifiers 30a and 30b to become flame light reception signals E1 ′ and E2 ′, and digitally output by the A / D conversion ports 35a and 35b of the MPU 15. It is converted into a received light signal and captured.

  Further, the flame light reception signals E1 and E2 from the flame detection units 12a and 12b are added by the addition amplifier 32 and output to the MPU 15 as the flame light reception signal E3, and converted into a digital light reception signal by the A / D conversion port 35c of the MPU 15. It is captured.

  Hereinafter, the same symbols are used before and after A / D conversion. The same applies to a light receiving signal E4 'described later.

  The non-flame detection unit 12c is for observing infrared energy emitted from a heating element other than the combustion flame existing in the monitoring area, and receives infrared energy in a wavelength band of approximately 5.0 μm to 7.0 μm. A non-flame light reception signal E4 converted into an electrical signal is output.

  The non-flame detection unit 12c is provided with an infrared transparent window 18-1, a non-flame detection sensor 16c, a pre-filter 24c, a preamplifier 26c, and a main amplifier 28c that are shared with the flame detection units 12a and 12b. The flame light reception signal E4 output from 28c is further amplified by the final amplifier 30c to become a flame light reception signal E4 ′, which is converted into a digital light reception signal by the A / D conversion port 35d of the MPU 15 and is captured.

  When the signal level of the light reception signal E3 obtained by adding the flame light reception signals E1 and E2, for example, the integral value ΣE3 of the light reception signal E3 for a predetermined period exceeds or exceeds a predetermined threshold, A ratio ΣE3 / Σ4 ′ of integral values of the non-flame light reception signal E4 ′ in the same period is calculated, and when this exceeds or exceeds another threshold value, it is determined that there is a flame.

(Outline of dirt test)
A test light source 60-1 that functions as a test light source is provided for the translucent window 18-1 of the flame detector 11-1. The test light source 60-1 is disposed on the central convex portion 54 on the front surface of the casing (case body) 50 of the flame detection device 10 which will be clarified in the following description, and is used for a dirt test, which is an item of self-test. Test light that becomes flame simulated light by driving 60-1 is output from the translucent test window 56-1, and this test light is disposed in the translucent window 18-1, and the flame detection sensors 16a and 16b and The non-flame detection sensor 16c receives light.

  Similarly, a test light source 60-2 and a test window 56-2 used for a stain test of the translucent window 18-2 of another flame detection unit 11-2 are arranged in the central convex portion 54.

  For example, krypton lamps are used as the test light sources 60-1 and 60-2. The test light source 60-1 is provided with a reflective hood 74-1 that functions as a reflector that reflects the test light toward the test window 56-1, that is, toward each detection sensor. On the other hand, the reflective hood 74-1 outputs test light from the test light source 60-1 only from the test window 56-1, and does not transmit it to the test window 56-2 side. Similarly, the test light source 60-2 is also provided with a reflective hood 74-2, and the test light is output only from the test window 56-2.

  In the example of FIG. 1, the reflective hoods 74-1 and 74-2 are integrated, and a reflective coating is applied to both surfaces of a light-blocking plate-like member.

  The stain test of the translucent window 18-1 is performed based on the flame light reception signal E3 obtained by adding the light reception signals E1 and E2 from the flame detection units 12a and 12b. When the test control unit 38 provided in the MPU 15 receives a test signal periodically transmitted from a fire receiving board (not shown), the test light sources 60-1 and 60-2 are sequentially driven to output test light. When the flame light reception signal E3 output from the adder 32 is read, the light attenuation rate is calculated by comparison with the initial state (the state without dirt), and the calculated light attenuation rate is greater than or equal to a predetermined threshold value or a predetermined threshold value. If it exceeds, a dirt alarm signal is transmitted to the fire receiving panel to output a dirt alarm, and the manager is encouraged to formulate a cleaning plan for the flame detector 10.

(Appearance and sensor unit)
2 is an explanatory view showing the appearance of the flame detection device, FIG. 3 is an explanatory view showing the flame detection device of FIG. 2 from the front, and FIG. 4 is a view of the central convex portion when the flame detection device of FIG. It is explanatory drawing which showed the test light source, the test window, and the flame detection part inside a translucent window in a partial cross section.

  As shown in FIGS. 2 to 4, the flame detection device 10 includes two sets of flame detections including the flame detection unit 11-1 of FIG. 1 in the sensor storage unit 52 of the front cover disposed on the front surface of the housing 50. Corresponding to the unit, infrared translucent windows 18-1 and 18-2 are provided.

  In addition, in the following description, when it is not necessary to distinguish the translucent windows 18-1 and 18-2, they may be referred to as translucent windows 18. Similarly, the test windows 56-1 and 56-2 may be referred to as test windows 56.

  In each of the translucent windows 18-1 and 18-2, the flame detection sensor 16a of the flame detection units 12a and 12b in the flame detection unit 11-1 and the other flame detection unit 11-2 shown in FIG. 16b and a non-flame detection sensor 16c of the non-flame detection unit 12c are arranged.

  Further, a central convex portion 54 is formed to project between the translucent windows 18-1 and 18-2 provided in the sensor storage portion 52. Test light sources 60-1 and 60-2 are built in the central convex portion 54, and test windows 56-1 and 56-2 are arranged on the left and right side walls.

  The test light source 60-1 outputs test light from the test window 56-1 toward the translucent window 18-1. The test light source 60-2 outputs test light from the test window 56-2 toward the translucent window 18-2.

  As shown in FIG. 5, a sensor unit is incorporated in the pair of translucent windows 18 shown in FIGS. The sensor unit is composed of a unit main body 62 and a unit cover 64, and a circuit board 48 is fixed and accommodated therein with screws 68.

  Flame detection sensors 16 a and 16 b are disposed adjacent to the circuit board 48. Light receiving openings 66a and 66b are formed at positions of the unit cover 56 facing the flame detection sensors 16a and 16b so that the light passing through the translucent window 18 from the monitoring area side can be received by the flame detection sensors 16a and 16b. I have to.

  In addition, a non-flame detection sensor 16c is disposed on the circuit board 48, and a light receiving opening 66c is formed at a position of the unit cover 64 facing the non-flame detection sensor 16c, and passes through the translucent window 18 from the monitoring area side. The non-flame detection sensor 16c can receive the received light.

(Configuration of the flame detection units 12a and 12b)
In the flame detection units 12a and 12b shown in FIG. 1, the flame detection sensors 16a and 16b emit infrared energy having an infrared wavelength band having a center wavelength of about 4.5 μm, which is radiated from the combustion flame along with CO ₂ resonance. The prefilters 24a and 24b select only signal components in a predetermined frequency band corresponding to the fluctuation frequency of the flame from the light reception signals output from the flame detection sensors 16a and 16b. The preamplifiers 26a, 26b amplify the signal components that have passed through the pre-filters 24a, 24b in the first stage, and further amplify the signal components with the main amplifiers 28a, 28b to output the flame light reception signals E1, E2. Then, the final stage amplifiers 30a and 30b amplify the signal to a signal level suitable for the flame determination process and output the flame light reception signals E1 ′ and E2 ′.

  Here, the flame detection sensors 16a and 16b include optical wavelength filters 20a and 20b and light receiving element portions 22a and 22b.

  The flame light reception signals E1 ′ and E2 ′ output from the flame detection units 12a and 12b via the final amplifiers 30a and 30b are converted into digital light reception signals E1 ′ and E2 ′ by A / D conversion ports 35a and 35b provided in the MPU 15. It is converted and read.

  The flame light reception signals E1 and E2 output from the flame detection units 12a and 12b are added by an addition amplifier 32, and the flame light reception signal E3 from the addition amplifier 32 is converted into a digital light reception signal by an A / D conversion port 35c provided in the MPU 15. E3 is read after being converted, and the determination unit 36 determines whether or not there is a flame based on the flame light reception signal E3. Each configuration will be specifically described below.

  In the present embodiment, the received light signals E1 'and E2' are not used to determine the presence or absence of flames, but may be determined using them as appropriate.

(Flame detection sensors 16a, 16b)
6 is an explanatory diagram showing a schematic configuration of the flame detection sensor, and FIG. 7 is a circuit diagram showing an equivalent circuit of the flame detection sensor of FIG.

  As shown in FIG. 6, the flame detection sensor 16 a includes a pyroelectric body 45 supported and arranged on the surface of the substrate 40, provided with a light receiving electrode 25, an FET 27 arranged on the back side of the substrate 40, and a high resistance A light receiving element portion 22a (not shown), a terminal 42 provided through the base portion 38 while supporting the substrate 40 on the base portion 38, and an optical wavelength in front of the light receiving element portion 22a (upward in the drawing). It has a package configuration comprising a cover member 44 provided with a filter 20a.

  Further, as shown in FIG. 7, an equivalent circuit of the light receiving element portion 22a is connected from the gate of the FET 27 to the gate terminal G through, for example, a parallel circuit of the pyroelectric body 45 and the high resistance 29, and the drain and source of the FET 27. Are connected to the drain terminal D and the source terminal S, respectively.

  Here, the optical wavelength filter 20a selectively transmits a predetermined wavelength band centered on 4.5 μm, and can be formed on a substrate such as silicon or sapphire by a known method, for example. The flame detection sensor 16b of the flame detection unit 12b has the same structure as the flame detection sensor 16a.

  Further, the non-flame detection sensor 16c of the non-flame detection unit 12c has the same structure as that of the flame detection sensor 16a, but the optical wavelength filter 22c is a cut that satisfactorily transmits infrared rays in a predetermined wavelength band generally exceeding 5.0 μm. The difference is that an on-filter (long-pass filter) is used.

  (Translucent Window 18) As shown in FIGS. 2 and 3, the translucent window 18-1 is monitored by the sensor unit of FIG. 6 in which the flame detection sensors 16a and 16b and the non-flame detection sensor 16c are housed. The upper surface side corresponding to the area side, which is provided at a predetermined opening of the sensor housing 52 provided on the front surface side of the flame detection sensors 16a, 16b and the non-flame detection sensor 16c, It is formed of an infrared translucent member such as sapphire glass.

  For this reason, the flame detection sensors 16a and 16b and the non-flame detection sensor 16c set the detection area of the visual field range having a predetermined spread angle by restricting the light reception limit visual field at the edge of the translucent window 18-1. Is done.

  Here, the sapphire glass constituting the translucent window 18-1 has a short wave path characteristic that transmits infrared rays in a wavelength band of approximately 7.0 μm or less in a favorable manner, in other words, a longer wavelength than approximately 7.0 μm. It functions as a filter member having a long wave cut characteristic that blocks infrared rays. Moreover, in this embodiment, the translucent window 18-1 is shared by the flame detection sensors 16a and 16b and the non-flame detection sensor 16c.

(Pre-filters 24a, 24b, 24c)
The pre-filters 24a and 24b of the flame detection units 12a and 12b in FIG. 1 function as a frequency selection unit, and perform flame determination processing from light reception signals output from the light receiving element portions 22a and 22b of the flame detection sensors 16a and 16b. For example, it is an active filter that passes only signal components in a specific frequency band to be used, and outputs a light reception signal composed of signal components in a specific frequency band to the preamplifiers 26a and 26b in the subsequent stage.

  Similarly, the pre-filter 24c is, for example, an active filter that passes only a signal component in a specific frequency band used for flame determination processing from the light reception signal output from the light receiving unit 22c of the non-flame detection sensor 16c. The pre-amplifier 26c outputs a light reception signal composed of a signal component in a specific frequency band.

  Such a frequency selection filter is appropriately arranged not only as a pre-filter but also from a preamplifier to a final stage amplifier, so that a signal is amplified while selecting (extracting) the frequency.

(Preamplifiers 26a, 26b, 26c and main amplifiers 28a, 28b, 28c)
The preamplifiers 26a and 26b amplify the light reception signals input via the pre-filters 24a and 24b at a first stage with a predetermined amplification factor, and the main amplifiers 28a and 28b amplify the light reception signals from the preamplifiers 26a and 26b, Output as flame light reception signals E1 and E2.

  The final stage amplifiers 30a and 30b finally adjust and amplify the light reception signals E1 and E2 to signal levels suitable for flame determination processing, and output the signals to the A / D conversion ports 35a and 35b of the MPU 15 as E1 ′ and E2 ′.

  Similarly, the preamplifier 26c amplifies the light reception signal output through the prefilter 24c at the first stage with a predetermined amplification factor, and the main amplifier 28c and the final stage amplifier 30c convert the light reception signal from the preamplifier 26c to a flame described later. The signal is amplified to a signal level suitable for determination processing, and is output as a flame light reception signal E4 and a flame light reception signal E4 ′.

(A / D conversion ports 35a, 35b, 35c)
The A / D conversion ports 35a, 35b, and 35c are A / D converters provided as input ports of the MPU 15. The A / D conversion ports 35a, 35b, and 35c are suitable for digital processing of the determination unit 15 using the flame light reception signals E1 ′ and E2 ′ and the added flame light reception signal E3. Convert to a digital signal and read it.

(Non-flame detection unit 12c)
The non-flame detection unit 12c includes a non-flame detection sensor 16c that converts infrared energy in a predetermined wavelength band different from the flame detection sensors 16a and 16b into an electrical signal and outputs the electrical signal. That is, the flame detection units 12a and 12b output flame light reception signals E1 and E2 obtained by converting infrared energy in a wavelength band having a central wavelength of approximately 4.5 μm, which is radiated from the combustion flame by CO ₂ resonance, into electrical signals. On the other hand, the non-flame detection unit 12c outputs a non-flame light reception signal E4 obtained by converting infrared energy in a wavelength band of approximately 5.0 μm to 7.0 μm into an electrical signal.

  Further, the non-flame detection unit 12c includes, after the non-flame detection sensor 16c, a pre-filter 24c that passes only a signal component in a predetermined frequency band from a light reception signal output from the non-flame detection sensor 16c, and a pre-filter 24c. A preamplifier 26c that amplifies the signal component that has passed through the filter 24c at the first stage, and a main amplifier 28c that amplifies the output from the preamplifier 26c.

  The non-flame light reception signal E4 output from the main amplifier 28c of the non-flame detection unit 12c is further adjusted and amplified by the final amplifier 30c to become a non-flame light reception signal E4 ′, and the digital light reception signal by the A / D conversion port 35d of the MPU 15 E4 ′ is converted and read and used by the determination unit 36 for flame determination processing.

(Configuration of non-flame detection sensor 16c)
The non-flame detection sensor 16c is an optical wavelength filter 20c that is a long-pass filter constituted by a cut-on filter that satisfactorily transmits infrared rays in a predetermined wavelength band that exceeds approximately 5.0 μm, and light that has passed through the optical wavelength filter 20c. A light receiving element portion 22c having an equivalent circuit similar to that of FIG. 7 that receives light, converts it into an electrical signal, and outputs the signal is provided, and a packaged structure is formed by the same structure as shown in FIG.

(Wavelength transmission characteristics of non-flame detection sensor 16c)
FIG. 8 is a characteristic diagram showing the transmittance at each wavelength of the optical wavelength filter and the translucent window applied to the embodiment of FIG.

  As shown in FIG. 8, the sapphire glass that is the translucent window 18-1 in FIG. 1 has a short wave path characteristic (or long wave cut characteristic) that allows infrared rays of approximately 7.0 μm or less to be transmitted satisfactorily. A transmittance characteristic 90 is obtained.

  Further, a transmission characteristic 92 that selectively transmits infrared energy in a wavelength band in the vicinity of the center wavelength is obtained by a bandpass filter having an optical wavelength filter 20a, 20b having a central wavelength in the vicinity of approximately 4.5 μm. By combining these, a band pass filter having a combined transmission characteristic 94 having a central wavelength around 4.5 μm is formed.

  On the other hand, the long-pass filter that constitutes the optical wavelength filter 20c provides a transmittance characteristic 96 having a cut-on filter characteristic that selectively transmits infrared rays in a predetermined wavelength band exceeding approximately 5.0 μm. By combining this with the transmission characteristic 90 of sapphire glass, a broadband bandpass filter having a synthesis characteristic 98 that selectively transmits infrared rays having a wavelength band of approximately 5.0 μm to 7.0 μm is formed.

(Judgment part 36)
FIG. 9 is a signal waveform diagram showing a flame light reception signal output from the flame detection unit of FIG. 1 when the infrared ray radiated from the combustion flame is observed. FIG. 9 (A) is a diagram from the A / D conversion port 35a. FIG. 9B shows the signal waveform of the light reception signal E2 ′ from the A / D conversion port 35b.

  FIGS. 9A and 9B are obtained simultaneously through the flame detection units 12a and 12b having the same configuration, and have similarities. If the amplification factors of the final stage amplifiers 30a and 30b are the same, the waveforms are almost the same. The flame light reception signal E3 has a waveform obtained by combining FIGS. 9A and 9B with the amplification factor of the addition amplifier 32 taken into account.

  In the present embodiment, the A / D conversion is performed by sampling the received light signal at 64 Hz, that is, 64 points of digital data are obtained per second for each signal.

  The determination unit 36 obtains a flame integral value ΣE3 that is the sum of absolute values of differences from the reference potential in units of T = 2 seconds (128 data) for the flame light reception signal shown in FIG. 9, and the flame integral value ΣE3 is a predetermined value. When the threshold value is exceeded or exceeded, the process proceeds to the relative ratio determination described below.

  When the flame integral value ΣE3 is equal to or more than a predetermined threshold value or exceeds the predetermined threshold value, the determination unit 36 obtains the non-flame integral value ΣE4 'in the same manner as the flame integral value ΣE3 is obtained for the same 2 seconds.

  Next, the determination unit 36 calculates a relative ratio (ΣE3 / ΣE4 ′) between the flame integral value ΣE3 and the non-flame integral value ΣE4 ′, and the relative ratio (ΣE3 / ΣE4 ′) exceeds a preset threshold value. In such a case, it is determined that the first element for determining the presence of flame is satisfied.

  Further, the determination unit 36 analyzes the result by performing a fast Fourier transform on the flame light reception signal E3 for the same 2 seconds (128 data) used for the calculation of ΣE3, and has a main component in a frequency band of 8 Hz or less, for example. If the second element for determining whether there is a flame is satisfied, and if both the first element and the second element are satisfied, it is determined that there is a flame.

  FIG. 10 is an explanatory diagram showing the frequency distribution of the flame light reception signal E3 obtained from the flame detection unit of FIG. 1 when the infrared rays emitted from the combustion flame are observed. As described above, the determination unit 36 performs fast Fourier transform on T = 2 seconds (128 data) of the flame light reception signal E3 to obtain, for example, a frequency distribution shown in FIG.

  As shown in FIG. 10, when the infrared ray radiated from the combustion flame is observed on the frequency axis, a frequency distribution showing a higher intensity on the low frequency side FL than about 8 Hz is obtained, so that the main frequency of the light reception signal E3 is obtained. It can be seen that the component exists in the frequency band FL up to 8 Hz. On the other hand, in the frequency band FH on the high frequency side exceeding 8 Hz and up to 16 Hz, a relatively low intensity distribution is shown. Such a distribution characteristic is a characteristic of a signal when a flame is observed.

For this reason, the flame judgment based on the frequency distribution of the flame light reception signal E3 is, for example, the relative intensity integral value on the low frequency side in the range up to 8 Hz ■ FL and the relative intensity integral value on the high frequency side in the range exceeding 8 Hz to 16 Hz ΣFH is obtained, and if the ratio ΣFL / ΣFH of both integral values is equal to or less than a preset threshold value, it is determined that the received light output corresponding to the flame has not been detected, and the second element for determining the presence of flame is satisfied. Suppose you didn't. On the other hand, when ΣFL / ΣFH exceeds the threshold value, it is assumed that the second element for determining the presence of flame is satisfied. The determination unit 36 repeats the above determinations every T = 2 seconds.

(Test control unit 38)
FIG. 11 is a time chart showing a drive signal for driving the test light source in pulses, FIG. 11A shows a drive signal E11 for the test light source 60-1, and FIG. 11B shows driving of the test light source 60-2. Signal E12 is shown.

  When the test control unit 38 receives the test signal periodically transmitted by the fire receiving panel, the test control unit 38 outputs the drive signals E11 and E12 shown in FIG. 11 to the test light sources 60-1 and 60-2 to emit light, thereby transmitting the light. The test light is output to the sex windows 18-1 and 18-2 to perform a dirt test.

  The test control unit 38 outputs the drive signals E1 and E2 over a period T1, for example, T1 = 2 seconds, the cycle of the drive signals E1 and E2 is T2, and the drive signals E1 and E2 are (T2 / 2). Has a phase shift.

  As a result, when the drive signal E11 is H level and the test light source 60-1 is emitting light, the drive signal E12 is L level and the test light source 60-2 is turned off, and the drive signal E11 is L level. When the test light source 60-1 is turned off, the drive signal E12 becomes H level and the test light source 60-2 is turned on, and the test light is alternately transmitted from the test windows 60-1 and 60-2. It outputs toward the translucent windows 18-1 and 18-2.

  For this reason, the test time for the stain test of both the translucent windows 18-1 and 18-2 by the test control unit 38 is T1 + (T2 / 2) obtained by adding a phase shift (T2 / 2) to the driving period T1. It will be time.

  On the other hand, in the conventional example of FIG. 16, since two sets of translucent windows are tested in order, for example, the drive of FIG. Subsequently, the drive of FIG. 11B is performed to test the contamination of the translucent window 18-2, and the entire test time for one flame detection device 10 is, for example, T = 4 seconds. However, in this embodiment, the time of just over 2 seconds, which is about half of the conventional time, is sufficient. For this reason, when performing the contamination test of a large number of flame detection devices 10 in order by transmitting test signals from the fire receiving panel, the time during which the control load due to the contamination test is applied to the fire receiving panel should be reduced to about half that of the conventional case. It is possible to maintain the original fire monitoring function by reducing the time when the control burden is applied to the fire receiving panel as much as possible.

(Stain test control)
The test control unit 38 provided in the MPU 15 of FIG. 1 operates when a test signal is received from the fire receiving board 10, and the test light sources 60-1 and 60-2 are driven to emit light by the drive signal shown in FIG. Then, the flame light receiving units 11-1 and 11-2 are irradiated with test light through the light-transmitting windows 18-1 and 18-2 to perform a stain test.

  For example, taking the stain test of the translucent window 18-1 as an example, the test control unit 38 drives the test light source 60-1 to emit light with the drive signal E11 of FIG. The light is output through the test window 56-1, and is incident on the flame detection sensors 16a and 16b through the translucent window 18-1. The flame simulated light from the test light source 60-1 includes 4.5 μm received by the flame detection sensors 16a and 16b, and has a fluctuation frequency of 2 to 8 Hz inherent to the flame.

  The translucent window 18-1 is not contaminated at the time of shipment from the factory, and the light reception level of the flame light reception signal E3 obtained in the contamination test at that time is stored in the memory of the MPU 15 as a reference light reception level. Used for calculation.

  That is, the light attenuation rate is obtained from the flame light reception signal E3 and the reference light reception level during the test. That is, the dimming rate at the time of shipment is zero. As the operation period elapses in the installation environment, dirt is attached to the translucent window 18-1, and the light attenuation rate gradually increases.

  The light attenuation rate may be obtained for the flame light reception signal E3 in this way, or may be obtained for any one, a plurality, or all of the flame light reception signals E1 ′, E2 ′ and the non-flame light reception signal E4 ′. The correction described below may be performed based on the light rate. Further, for example, a stain alarm or a stain warning alarm may be performed by obtaining a representative value or an average value of each dimming rate.

  The test control unit 38 obtains the light attenuation rate by the stain test, obtains a correction value that is the reciprocal of (1−light attenuation rate), stores the correction value in the memory, and detects the flame light reception signal E3 detected in the subsequent operation state and The light reception level (light reception value) of the non-flame light reception signal E4 ′ is divided by the correction value to perform the dirt correction, and the determination unit 36 performs a fire based on the light reception value of the flame correction light reception signal E3 and the non-flame light reception signal E4 ′. to decide.

  In addition, the test control unit 38 is preset with a threshold value that is a dimming rate corresponding to the limit at which the smear correction is impossible, for example, a threshold value 0.5, and the dimming rate obtained in the smear test is equal to or greater than the threshold value. Or, when the threshold value is exceeded, it is determined that the light transmission window 18-1 cannot be corrected for dirt (for example, the entire monitoring area cannot be monitored even if correction is performed). Control to send a warning signal and output a dirt warning.

  In addition, the test control unit 38 sets a predetermined warning threshold value smaller than the threshold value, for example, a warning threshold value 0.4 in advance, and when the dimming rate obtained in the dirt test is equal to or higher than the warning threshold value or exceeds the warning threshold value, Therefore, it is possible to perform control to transmit a dirt notice alarm signal to the fire receiving board and output a dirt notice alarm.

  In the stain test of this embodiment, the stain on the translucent window 18 and the stain on the test window 56 are detected together. When the reference light reception level is acquired, not only the translucent window 18 but also the test window 56 is not dirty.

[Embodiment of flame detection apparatus sharing test light source]
FIG. 12 is an explanatory view showing an embodiment of a flame detection apparatus sharing a test light source from the front, and FIG. 13 is a view of a test light source and a test window arranged on a central convex portion when the flame detection apparatus of FIG. FIG. 14 is a time chart showing a drive signal for driving the test light source of FIG. 12 in a pulsed manner. FIG. 14 is an explanatory diagram showing a partial cross section of the flame detector disposed inside the translucent window.

  As shown in FIG.12 and FIG.13, in the flame detection apparatus 10 of this embodiment, the test windows 56-1, 56 arrange | positioned at the both sides of the center convex part 54 of the sensor accommodating part 52 used as a housing | casing front surface. -2, one test light source 60 is disposed, and the test light from the test light source 60 is sent to the flame detection sensors 16 a and 16 b via the translucent windows 18-1 and 18-2 located on both sides thereof. And the non-flame detection sensor 16c is irradiated with test light. Other configurations are the same as those of the embodiment of FIGS.

  Thus, by sharing the test light source 60 for the light-transmitting windows 18-1 and 18-2, the light-transmitting windows 18-1 and 18- are used in the flame detection apparatus of FIGS. Compared with the case where the test light sources 60-1 and 60-2 are provided corresponding to each of the two and the dirt test is performed, the central convex portion 54 in which the test light source 60 is accommodated can be reduced in size, and the central convex portion 54 The restriction (reduction) of the detection area due to the restriction of the structure can be further relaxed.

  FIG. 14 is a time chart showing drive signals for driving the test light source of FIG. 12 in pulses. In the case of the present embodiment, when the test control unit 38 receives a test signal periodically transmitted by the fire receiving board, the test control unit 38 generates the drive signal E11 (corresponding to the drive signal of FIG. 11A) shown in FIG. The light is driven to emit light, and the test light is output to the translucent windows 18-1 and 18-2 through the test windows 56-1 and 56-2 located on both sides to perform a stain test.

  Therefore, only by driving the test light source 60 by the drive signal E11, the stain test of the light transmissive windows 18-1 and 18-2 can be performed at the same time, corresponding to each of the light transmissive windows 18-1 and 18-2. Unlike the case where the test light sources 60-1 and 60-2 are separately provided, it is not necessary to perform the drive by the drive signal of FIG. 11B. Therefore, the test time can be shortened and the test light source 60 can be driven. Current consumption can be reduced.

[Modification of the present invention]
(Average of received light signal)
In the above embodiment, the determination unit 36 determines the presence or absence of flame using the flame light reception signal E3 obtained by adding the flame light reception signals E1 and E2 from the flame detection units 12a and 12b by the adder 32. For example, the average of the flame light reception signals E1 and E2 from the flame detection units 12a and 12b may be obtained, the average light reception signal may be taken in, and the presence or absence of the flame may be determined by the determination unit 36.

(Two wavelength method)
In the above-described embodiment, as a two-wavelength flame detection device, each infrared ray in the wavelength band near 4.5 μm and the wavelength band near 5.0 μm, which is the CO ₂ resonance radiation band of the combustion flame, is observed. However, the flame may be determined by observing each infrared ray in the wavelength band near 4.5 μm and in the wavelength band near 2.3 μm.

(3-wavelength method)
Further, for example, infrared energy in the wavelength band near 2.3 μm is detected on the short wavelength side of the 4.5 μm band, which is the resonance emission band of CO ₂ of the combustion flame, and infrared radiation in the wavelength band near 5.0 μm is detected 2 A three-wavelength flame detection device may be used which detects by the same method as that of the wavelength method and uses the relative ratio of the received light signals in these three wavelength bands according to the characteristics of radiation from the flame as a determination factor for the presence of flame.

  Of course, it may be a one-wavelength type, two-wavelength type, three-wavelength type, or other type of flame detection device using other wavelength bands.

  Moreover, you may apply to the flame detection apparatus which observes radiation energy other than infrared rays.

(Sensitivity test)
Further, the test control unit 38 of the above embodiment may perform a sensitivity test of the flame detection sensors 16a and 16b in addition to the dirt test. In the sensitivity test of the test control unit 38, when a test signal periodically transmitted from the fire receiving panel is received, the test light is incident on the flame detection sensors 16a and 16b and received based on the light reception level at this time. Until the sensitivity is detected and the light reception sensitivity falls to the predetermined threshold sensitivity, the light reception value is corrected with a correction value that is the reciprocal of the detection sensitivity, and the detection sensitivity falls to the predetermined sensitivity threshold, making correction impossible. In the case of failure, control is performed to transmit a failure signal of the flame detection sensors 16a and 16b to the disaster prevention reception panel and output a sensor failure alarm. This sensitivity test is similarly performed for the non-flame detection sensor 16c.

(Other)
Further, the present invention includes appropriate modifications that do not impair the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

10: Flame detector 11-1: Flame detectors 12a, 12b: Flame detector unit 12c: Non-flame detector unit 15: MPU
16a, 16b: Flame detection sensor 16c: Non-flame detection sensors 18-1, 18-2: Translucent windows 20a, 20b, 20c: Optical wavelength filters 22a, 22b: Flame detection element unit 22c: Non-flame detection element unit 24a , 24b, 24c: Pre-filter 25: Light receiving electrodes 26a, 26b, 26c: Preamplifier 27: FET
28a, 28b, 28c: main amplifiers 30a, 30b, 30c: final amplifier 32: addition amplifiers 35a, 35b, 35c, 35d: A / D conversion port 36: determination unit 38: test control unit 45: pyroelectric body 50: Case 52: Sensor storage portion 54: Center convex portions 56-1, 56-2: Test windows 60, 60-1, 60-2: Test light sources 74-1, 74-2: Reflective hood

Claims (2)

A flame detection apparatus provided with two sets of flame detectors for observing radiation energy radiated from a combustion flame with a detection sensor through a translucent window and determining the presence or absence of the combustion flame,
Between the translucent windows disposed on the front surface of the housing, a central convex portion disposed in the vertical direction,
A pair of test light sources that irradiate each of the detection sensors from the test windows disposed on both sides of the central convex portion through the translucent window;
A test control unit that alternately pulse-drives the other light emission while stopping one of the pair of test light sources;
A flame detection device characterized by that.
A flame detection device provided with two sets of flame detectors for observing radiation energy emitted from a combustion flame with a detection sensor through a translucent window to determine the presence or absence of the combustion flame,
A central convex portion provided between the translucent windows disposed on the front surface of the housing;
One test light source that irradiates each of the light receiving elements with test light from the test windows disposed on both sides of the central convex portion through the translucent window;
Is provided,
A flame detection apparatus, wherein the test light from the one test light source is detected for the same period by each of the detection sensors of the two sets of detection units, and self-diagnosis is performed based on the detected test light quantity.

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