JPH04124517A - Flame detector - Google Patents

Abstract

PURPOSE:To distinguish solar light from flame and to integrally form photo detectors different in a sensitivity wavelength region by providing a plurality of photo detectors having detecting sensitivity located in wavelength regions different from each other, and a controller to detect flame and the trouble of the photo detector based on a detecting signal from each of the photo detectors. CONSTITUTION:In a sensor 1A, after infrared rays are removed from incident light by means of a filter 2, only ultraviolet rays are permeated through a filter 3. A fluorescent substance 4 is excited by means of the ultraviolet rays, having a short wavelength, of the ultraviolet rays to emit visible light. In a sensor 1B, a detecting signal (b) responding to an amount of near ultraviolet rays of incident light is outputted. In a sensor 1C, a detecting signal (c) responding to an amount of visible light of incident light is outputted. Each sensor generates a detecting signal in a given level region responding to a kind of a detecting flame through selection of the characteristics of a working filter, a fluorescent substance, and a solar battery. The detecting signals (a), (b), and (c) are fed to a controller 8. By treating a detecting signal based on a given flame detecting condition, the controller 8 outputs an alarm signal indicating that a sensor is failed in operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flame detector for detecting flame in a combustion device or the like.

[Conventional technology]

Conventionally, flame detectors for detecting the flame of gas burners in water heaters, etc., include visible light detectors using CdS cells, ultraviolet detectors using gas-filled discharge tubes, etc., and Pb detectors.
Infrared detectors using S cells and the like are known. These detectors are sensitive to different wavelength regions of light, and have different structures and driving conditions. Further, one of the above detectors is usually used as a flame detector.

[Problem to be solved by the invention 1 Conventionally, one of the above-mentioned visible light detector, ultraviolet detector, and infrared detector is used as a flame detector, so it is difficult to distinguish it from sunlight, resulting in malfunctions. Furthermore, if one detector fails, flame detection becomes impossible. Therefore, it is possible to integrate the three detectors mentioned above and set their respective wavelength sensitivities to be distinguishable from sunlight, but since each detector has a different structure and driving conditions, it is difficult to integrate them. there were.

This invention was made in order to solve the above-mentioned problems, and provides a flame detector that can distinguish between sunlight and flame, as well as easily integrating photodetectors with different sensitivity wavelength ranges. The purpose is to provide a flame detector that can perform

[Means for Solving the Problems] In the present invention, a plurality of photodetectors having detection sensitivities for different wavelength regions of light are provided, and flame detection and detection are performed based on the detection signal of each photodetector. A controller is provided to detect a failure of the photodetector.

[Function] By selecting the sensitivity wavelength range of a plurality of photodetectors according to the type of flame to be detected, detection can be performed separately from sunlight, and one or a predetermined number of photodetectors can be used for detection. Even in the event of a failure, flame detection will still occur with other normal photodetectors.

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

In Fig. 1, LA, IB, and IC are sensors as photodetectors having detection sensitivities for light wavelengths different from each other, and 8 is a controller that processes detection signals a, b, and c of each sensor IA, IB, and IC. be.

Next, the configurations of the sensors IA, IB, and IC will be explained.

Note that the same reference numerals are given to the sensors IA, IB, and IC that have the same functions.

Sensor IA has an infrared cut filter 2, an ultraviolet transmission filter 3, and ultraviolet rays other than near ultraviolet rays (ultraviolet rays with short wavelengths).
It is constructed by laminating a phosphor 4 that emits visible light when excited by the phosphor, an ultraviolet cut filter 5, an amorphous silicon solar cell (hereinafter referred to as a solar cell) 6, and the like.

Sensor IB uses a phosphor 7 that emits visible light when excited by near ultraviolet light in place of the phosphor 4 of sensor IA, and other parts are configured the same as sensor IA. .

The sensor IC is composed of an infrared cut filter 2, an ultraviolet cut filter 5, and a solar cell 6.

Note that these sensors IA, IB, and Ic are housed in one case and integrated so that a common light is incident thereon.

According to the above configuration, in the sensor IA, the infrared rays of the incident light are first removed by the infrared cut filter 2, and then only the ultraviolet rays are transmitted by the ultraviolet transmission filter 3.

Among these ultraviolet rays, the phosphor 4 is excited by ultraviolet rays having short wavelengths excluding near ultraviolet rays, and the phosphor 4 emits visible light. This visible light irradiates the solar cell 6 through the ultraviolet cut filter 5. The ultraviolet cut filter 5 is provided for the purpose of preventing errors in the detection signal and deterioration of the solar cell 6 due to irradiation of the solar cell 6 with ultraviolet rays that have passed through the phosphor 4 . By irradiating the solar cell 6 with the visible light of the phosphor 4, the solar cell 6 generates a detection signal a corresponding to the amount of ultraviolet light with a short wavelength among the incident light.

In sensor IB, only the near ultraviolet rays that have passed through the ultraviolet transmission filter 3 are transmitted by the phosphor 7, so that
The solar cell 6 outputs a detection signal corresponding to the amount of near ultraviolet rays in the incident light.

In the sensor IC, only visible light passes through the infrared cut filter 2 and the ultraviolet cut filter 5, so the solar cell 6 outputs a detection signal C corresponding to the amount of visible light among the incident light.

Each of the above-mentioned sensors IA, IB, and IC detects a flame, such as a gas combustion flame, an oil It is configured to generate a detection signal in a predetermined level range depending on the type of flame such as combustion flame.

Therefore, a w + b N * CH is the preset upper limit, aL HbL I CL is the preset lower limit, abH, bCM, CaH is the preset a/b, b/c, c/a. Upper limit of ab
a/b with preset t, bct, and CaL
, b/c, and c/a, when there is a normal flame, the detection signal a of sensor IA is a L < a <
a s range, and the detection signal of sensor IB is <
The range is b<bN, and the detection signal C of sensor IC is CL
<C<Cs. This allows it to be distinguished from the ultraviolet, near-ultraviolet, and visible light spectra of sunlight.

These detection signals a, b, and c are sent to the controller 8. The controller 8 satisfies the following flame detection conditions (1) to (6).
) to output a flame detection signal or an alarm signal indicating that the sensor IA, IB, Ic has failed.

Flame detection conditions a, <a<a, -(1)b, <b
<b, 4...(2) OL <c<
c14 - (3) a b L < a
/ b < a b s − (4) bcL
<b/c<bc, =-(5)cac<
c/a<can=-(6) FIG. 2 is a flowchart showing the procedure of processing executed by the controller 8.

First, the detection signals a, b, and C are input in step STI, and then the above (1) is input in steps ST2, Sr1, and Sr4.
) to (3) are satisfied. Step ST when the detection conditions are met
5. Proceed to either Sr6 or Sr7, and then proceed to (4) above.
It is checked whether the detection conditions of (6) to (6) are satisfied or not. Next, in step ST8, it is checked whether some of the detection conditions (4) to (5) are satisfied.

If all detection conditions are met, a flame detection signal is output in step ST9, and the combustor continues to operate. If one or two of the detection conditions are met, the sensor IA is detected in step 5TIO.

Outputs an alarm signal indicating that one of the IB and IC is faulty. If all the detection conditions are not met, a sensor failure warning signal is output in step 5T11, and the operation of the combustor is stopped in step 5T12.

In the above embodiment, the wavelength ranges to be detected are ultraviolet rays, near ultraviolet rays, and visible light, but a sensor that detects infrared rays may be provided. Furthermore, the number of sensors may be increased to four or more by dividing each area into smaller areas and providing sensors for each area.

Furthermore, the above-mentioned detection conditions (
It is also possible to perform flame detection and failure detection by applying 1) to (6) and the above flowchart.

〔Effect of the invention〕

According to this invention, a plurality of photodetectors having detection sensitivities in two different light wavelength regions are provided, and flame detection and failure of the photodetector are detected based on the detection signal of each photodetector. By selecting the sensitivity wavelength range of the plurality of photodetectors according to the type of flame to be detected, detection can be performed separately from sunlight. Even if a photodetector fails, flame detection is performed using other normal photodetectors. Further, by using an amorphous solar cell as a photodetector, five or more photodetectors can be easily integrated with substantially the same configuration and driving conditions. Amorphous solar cells have almost the same sensitivity characteristics as the human eye, and desired sensitivity characteristics can be easily obtained by changing the process steps.
This provides the effect of enabling highly accurate detection.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a flame detector according to an embodiment of the present invention, and FIG. 2 is a flowchart showing the procedure of processing executed by a controller of the flame detector. IA, IB, and IC are sensors, and 8 is a controller. Patent applicant: Yamatake Honeywell Co., Ltd.

Claims (3)

[Claims] (1) A plurality of photodetectors that have detection sensitivities for different wavelength regions of light and are designed to receive common light, and detection signals from the plurality of photodetectors are input. and a controller configured to output a flame detection signal when all or a predetermined number of detection signals are normal, and to output an alarm signal when all or a predetermined number of detection signals are abnormal. (2) Two of the plurality of photodetectors are combined to form one or more pairs, and the controller calculates the ratio of the detection signals of the two photodetectors forming each pair, and calculates the ratio of the detection signals of the two photodetectors of each pair. The flame detector according to claim 1, wherein an alarm signal is output when each ratio value is different from a set value. (3) The flame detector according to claim (1), wherein the plurality of photodetectors include amorphous silicon solar cells.