JPH1137896A - Method and apparatus for detecting deterioration of ultraviolet phototube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect deterioration of an ultraviolet phototube in its early stages. SOLUTION: In a state where a flame is present, an ultraviolet phototube 7 is applied with a deterioration judging voltage V2 lower than a normal discharge starting voltage V0 and it is judged that the ultraviolet phototube is deteriorated if a flame present signal is outputted. A plurality of deterioration judging voltages V2 are set stepwise and applied to the ultraviolet phototude and then the extent of deterioration thereof is determined based on the output signal therefrom. Under a state where flame is present, a flame detection voltage V1 higher than the normal discharge starting voltage V0 and a deterioration judging voltage V2 lower than the normal discharge starting voltage V0 are applied alternately to the ultraviolet phototube and a decision is made that the ultraviolet phototube is deteriorated if a flame present signal is outputted upon application of the deterioration judging voltage V2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining deterioration of an ultraviolet photoelectric tube (also referred to as an ultraviolet sensor) used as a flame detector, and is applied to a combustion device or a fire alarm device.

[0002]

2. Description of the Related Art An ultraviolet photoelectric tube is used as one of flame detectors. The ultraviolet phototube detects the state of a flame by using a phenomenon (photoelectric effect) in which electrons jump from the surface of a metal when light is applied to the surface of the metal, and discharge generated when ultraviolet rays emitted from the flame enter the phototube. It is configured to detect the flame using the phenomenon.

[0003]

The performance of an ultraviolet photoelectric tube may deteriorate due to aging. When the performance deteriorates, an erroneous signal indicating that there is a flame may be output due to self-discharge even in a state where there is no flame. In that case, when a misfire occurs during the ignition trial of the combustion device, an erroneous signal indicating that there is a flame is output even though there is no flame, the fuel valve is opened and the fuel leaks to the surroundings, which is dangerous. The same applies to the case where a flame is extinguished in the middle of combustion, and the open state of the fuel valve is continued due to an erroneous signal indicating that there is a flame, and fuel leaks to the surroundings, which is dangerous. SUMMARY OF THE INVENTION It is an object of the present invention to detect deterioration of an ultraviolet phototube early.

[0004]

According to the present invention, when the ultraviolet photoelectric tube is deteriorated, the discharge starting voltage is lowered, and in a slightly deteriorated state, an erroneous signal indicating that there is no flame is not output in a state where there is no flame. When the discharge start voltage drops to a very low level due to a deteriorated state, it is based on technical knowledge that an erroneous signal indicating that there is a flame will be output in a state where there is no flame, and in a state where there is a flame, when a low deterioration determination voltage V ₂ than the discharge start voltage V ₀ which time non-degraded applied to UV flame sensor, the flame presence signal is output during this degradation determination voltage V ₂ is applied, determining that the degradation of the UV flame sensor The first characteristic is that the deterioration determination voltage V ₂
The second feature is that a plurality of are set stepwise and applied to the ultraviolet phototube, and the degree of deterioration of the ultraviolet phototube is determined stepwise based on an output signal from the ultraviolet phototube, and in a state where there is a flame, undegraded during the discharge starting voltage and high flame detection voltages V ₁ from V ₀ and the discharge starting voltage lower deterioration determination voltage V ₂ than V ₀ is applied to the UV flame sensor alternately, there flames during the degradation determination voltage V ₂ applied When a signal is output,
A third feature is that it is determined that the ultraviolet photoelectric tube is deteriorated.

Further, the present invention includes a UV flame sensor, and a voltage applying means for applying a low deterioration determination voltage V ₂ than the discharge start voltage V ₀ which time non-degraded in the UV flame sensor, the flame during the degradation determination voltage V ₂ applied when the presence signal is outputted, that a degradation determiner means and degradation of the UV flame sensor and the fourth feature, the voltage applying means, stepwise plurality sets the deterioration determination voltage V ₂ A fifth feature is to have a function of applying to the ultraviolet phototube, and the deterioration determining means has a function of stepwise determining the degree of deterioration of the ultraviolet phototube based on an output signal from the ultraviolet phototube, and UV flame sensor, and a voltage applying means for applying a non-degraded at the discharge starting voltage and high flame detection voltages V ₁ from V ₀ to the discharge starting voltage V low deterioration determination voltage V ₂ than ₀ alternately to the UV flame sensor, the deterioration Size When the flame presence signal when the constant voltage V ₂ applied is outputted, further comprising a determining deterioration determination device that the deterioration of the UV flame sensor is a sixth feature of the.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultraviolet photoelectric tube is used as a flame detector, and a voltage is intermittently applied to the ultraviolet photoelectric tube by a voltage applying means, and the presence or absence of a flame is determined based on an output signal from the ultraviolet photoelectric tube when the voltage is applied. Determine. The voltage applied to the ultraviolet phototube is based on a discharge starting voltage V ₀ in a normal state, that is, a state in which the ultraviolet phototube is not deteriorated.
Set the discharge start voltage V ₀ from the high flame detection voltages V ₁ and lower than the discharge start voltage V ₀ deterioration determination voltage V _2, and applies these to voltages V _1, V ₂ and intermittently alternately UV flame sensor . As applied method, the flame detection voltages V ₁ each time applied a plurality of times, the deterioration determination voltage V ₂ can be applied once. Moreover, until passage of a predetermined after the start burning time intermittently applying only flame detection voltage V _1, when a predetermined time has elapsed, it is also possible to apply a deterioration determination voltage V ₂ a plurality of times intermittently.

If the ultraviolet photoelectric tube has not deteriorated, a flame presence signal is output when the flame detection voltage V ₁ is applied in a state where there is actually a flame, and the deterioration determination voltage V ₂
Is applied, a flameless signal is output. However,
When UV flame sensor deteriorates, due to self-discharge, even by applying a voltage lower than the discharge start voltage V _0, the flame presence signal is output from the UV flame sensor. This is due to the fact that when the ultraviolet photoelectric tube deteriorates, the discharge starting voltage decreases. Therefore, the deterioration determining means for determining deterioration of UV flame sensor provided, when the flame presence signal is output when applying the deterioration determination voltage V _2, so as to determine the deterioration of the UV flame sensor. In other words, when there is no deterioration in a state where the flame actually exists, the flame detection voltage V ₁
When applying a flame presence signal is output, although the flame absence signal when applying the deterioration determination voltage V ₂ is outputted, the UV flame sensor deteriorates, even upon application of a flame detection voltages V ₁ since the flame presence signal even when applying the deterioration determination voltage V ₂ is to be output, it detects this and determines deterioration of the UV flame sensor.

[0008] degradation of the aforementioned UV flame sensor and have set the deterioration judgment voltage V ₂ to be detected at an early mild condition, a false signal of there flame to the flame becomes severe deterioration state is not Before output, deterioration can be detected. In mild deterioration state, the false signal of the presence flame during flame detection voltages V ₁ applied in flame absence is not outputted, it becomes severe deterioration state, the discharge starting voltage is reduced to very low levels, flame absence At the flame detection voltage V
_{When 1 is} applied, an erroneous signal indicating that there is a flame is output. As described above, by detecting the deterioration in the initial mild state, the ultraviolet photoelectric tube is replaced before the severe deterioration state is reached. And the accident that the fuel valve of the combustion device is left open can be prevented beforehand.

[0009] It is also possible to the deterioration determination voltage V ₂ stepwise plurality configure, so as to determine the extent of the UV flame sensor degradation stages. For example, a first deterioration determination voltage V _21, will be described case of setting two of lower than the first deterioration determination voltage V ₂₁ second deterioration determination voltage V _22.
Flame presence signal is output when the application of the first deterioration determination voltage V _21, when the flame absence signal is output when the application of the second deterioration determination voltage V ₂₂ determines that a relatively mild degradation,
When the flame presence signal is output both when the first deterioration determination voltage V ₂₁ is applied and when the second deterioration determination voltage V ₂₂ is applied, it is determined that the deterioration is further advanced, and the ultraviolet photoelectric tube is The degree of deterioration is determined stepwise. Deterioration judgment voltage V
₂ can be set to three or more. By judging the degree of deterioration step by step, it is possible to select a measure according to the degree of deterioration of the ultraviolet photoelectric tube.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a combustion apparatus will be described below with reference to the drawings. This combustion device
Used as a heating device for boilers and the like.

In FIG. 1, a fuel line 2 and a blower 3 are connected to a combustion device 1. A fuel valve 4 is provided in the fuel line 2, and the supply of the fuel gas is controlled by opening and closing the fuel valve 4. An electric motor 5 is provided in the blower 3, and an impeller (not shown) is rotated by the electric motor 5 to supply combustion air to the combustion device 1. When the combustion device 1 is provided in a steam boiler, the operation and stop of the combustion device 1 are controlled according to the steam pressure in the can. That is, when the steam pressure in the can reaches the first set value, the combustion device 1 is stopped, and when the steam pressure in the can decreases to the second set value, the combustion device 1 is started. At the time of start-up, the blower 3 is operated to perform a pre-purge for about 20 seconds. Then, the process proceeds to an ignition trial, an igniter (not shown) is operated for a predetermined time, and the fuel valve 4 is opened to supply fuel. Further, when stopping, the fuel valve 4 is closed to stop the fuel, post-purge is performed for about 20 seconds, and then the blower 3
To stop. These controls are performed by the controller 6.

The burning device 1 is provided with an ultraviolet photoelectric tube 7 as a flame detector, and the ultraviolet photoelectric tube 7 detects ultraviolet rays emitted from the flame to detect the presence or absence of the flame. A voltage is applied to the ultraviolet photoelectric tube 7 by voltage applying means 8,
The controller 6 determines the presence or absence of a flame based on the output signal of the ultraviolet photoelectric tube 7 with respect to the applied voltage. When a misfire occurs during an ignition trial or when a flame is extinguished during combustion, this is detected by the ultraviolet phototube 7, the fuel valve 4 is closed to stop the fuel, and an alarm is issued. A plurality of types of voltages are applied to the ultraviolet photoelectric tube 7 by the voltage applying means 8,
Based on the output signals from the ultraviolet phototube 7 corresponding to the applied voltages, the deterioration judgment means 9 judges whether or not the ultraviolet phototube 7 is deteriorated or the degree of the deterioration.

FIG. 2 shows one embodiment of the present invention, and shows the relationship between the voltage applied by the voltage applying means 8 and the output signal from the ultraviolet phototube 7 when the combustion device 1 is burning. (The horizontal axis is time.) The flame detection voltage V ₁ and the deterioration determination voltage V
₂ types are set. The flame detection voltage V ₁ is set higher than the discharge start voltage V ₀ when the ultraviolet photoelectric tube 7 is not deteriorated, and the deterioration determination voltage V ₂ is set lower than the discharge start voltage V ₀ (for example, V ₀ = 130 volts, V
₁ = 160 volts, V ₂ = 100 volts). The discharge start voltage V ₀ corresponds to the lowest applied voltage at which a flame signal can be output when a voltage is applied to the non-degraded ultraviolet phototube 7 in a state where there is a flame. The flame detection voltage V ₁ and the deterioration determination voltage V ₂ are alternately and intermittently applied to the ultraviolet photoelectric tube 7. That is, the flame detection voltages V ₁ is applied a predetermined time first, temporarily stopped the application of the voltage, then the deterioration determination voltage V
₂ , the application of the voltage is temporarily stopped, and the application of these voltages V ₁ and V ₂ is repeated. The cycle of applying each voltage is set to about 50 msec.

[0014] When the UV flame sensor 7 is normal (when not deteriorated), in a state where there is actually fire, flame presence signal "1" upon application of a flame detection voltage V ₁ is output deterioration determination voltage V _{When 2} is applied, a no-flame signal "0" is output. However, the UV flame sensor 7 is degraded, due to self-discharge, even so the flame presence signal "1" is output when applying the deterioration determination voltage V _2. This is because when the ultraviolet photoelectric tube 7 deteriorates, the discharge starting voltage gradually decreases from the level of V ₀ and reaches the level of V ₂ . Therefore, when the flame presence signal “1” is output when the deterioration determination voltage V _{2 is} applied, it is determined that the ultraviolet photoelectric tube 7 is deteriorated. The deterioration of the ultraviolet photoelectric tube 7 is still in an initial mild state, and has not yet reached a severe deterioration state in which an erroneous signal indicating the presence of a flame is output without the presence of a flame.
It usually takes hundreds of hours to reach a severe to a severe degradation. Therefore, when it is determined that the battery is deteriorated, a warning is issued, but the operation of the boiler is continued, and the ultraviolet photoelectric tube 7 is replaced at an opportunity. As described above, the deterioration is detected in the initial mild state, and the UV photoelectric tube 7 is detected before the severe deterioration state is reached.
By replacing the fuel cell, it is possible to prevent the accident that the fuel valve 4 is left open by outputting an erroneous signal indicating that there is no flame and that there is no flame at the time of misfiring or flame-out in the middle. Further, by applying continuously a flame detection voltages V ₁ and the deterioration determination voltage V ₂ alternately, can be carried out in parallel the determination of the presence or absence of determining deterioration of the presence or absence of the flame. Therefore, the deterioration of the ultraviolet photoelectric tube 7 can be always determined during the combustion, and the deterioration can be detected immediately when the deterioration occurs. In actual determination, it is determined based on how many flame presence signals “1” are output within a unit time when the deterioration determination voltage V _{2 is} applied (for example, eight or more per second).

FIG. 3 shows another embodiment of the present invention, in which the relationship between the voltage applied by the voltage applying means 8 and the output signal from the ultraviolet phototube 7 when the combustion device 1 is burning. (The horizontal axis is time). Deterioration judgment voltage V ₂
The first deterioration determination voltage V ₂₁ and the second deterioration determination voltage V
Set ₂₂ two, and three kinds of voltages combined with flame detection voltages V ₁ is applied to the UV flame sensor 7. Flame detection voltage V ₁
Are set higher than the discharge start voltage V ₀ when the ultraviolet photoelectric tube 7 is not deteriorated, and the first deterioration judgment voltage V ₂₁ and the second deterioration judgment voltage V ₂₂ are set lower than the discharge start voltage V _0. There is set further than the first deterioration determination voltage V ₂₁ low second deterioration determination voltage V ₂₂ (e.g., V ₀ = 130
Volt, V ₁ = 160 volts, V ₂₁ = 110 volts, V
₂₂ = 100 volts). As compared with the embodiment shown in FIG.
V ₂ is set to V _22, and V ₂₁ is set between V ₀ and V ₂ . The discharge start voltage V ₀ corresponds to the lowest applied voltage at which a flame signal can be output when a voltage is applied to the non-degraded ultraviolet phototube 7 in a state where there is a flame. Flame detection voltage V ₁ , first deterioration determination voltage V _21, and second deterioration determination voltage V
₂₂ is applied to the ultraviolet photoelectric tube 7 sequentially and intermittently. That is, when the first application of a flame detection voltages V ₁ given time, temporarily stops application of the voltage, then the first deterioration determination voltage V ₂₁ is applied a predetermined time, once stop the application of voltage, further second
The deterioration determination voltage V ₂₂ is applied a predetermined time, and temporarily stopping the application of voltage, to perform repeat application of these voltages _{V 1, V 21, V 22} . The cycle of applying each voltage is
In each case, it is set to about 50 msec.

[0016] When the UV flame sensor 7 is normal (when not deteriorated), in a state where there is actually a flame, is outputted flame presence signal "1" upon application of a flame detection voltage V _1, the first deterioration determination It is output flame absence signal "0" when a voltage is applied to V _21, the flame absence signal "0" is output upon application of a second degradation determination voltage V _22. However, when the ultraviolet photoelectric tube 7 is deteriorated, the flame presence signal “1” is output even when the first deterioration determination voltage V ₂₁ or the second deterioration determination voltage V ₂₂ is applied due to self-discharge. This is because when the UV flame sensor 7 deteriorates, the discharge starting voltage decreases gradually from the level of V _0, it is due to reach a level of V ₂₁ or V _22. Therefore, the first deterioration determination voltage V ₂₁
Is output flame presence signal "1" when applying, when the flame absence signal when applying the second deterioration determination voltage V ₂₂ "0" is output, determines that a relatively mild degradation as a first degradation stage I do. When the flame presence signal “1” is output both when the first deterioration determination voltage V ₂₁ is applied and when the second deterioration determination voltage V ₂₂ is applied, the deterioration further progresses as the second deterioration stage. The state is determined, and the degree of deterioration of the ultraviolet photoelectric tube 7 is determined stepwise. By judging the degree of deterioration step by step, it is possible to select a countermeasure according to the degree of deterioration of the ultraviolet phototube 7. For example, when the degree of deterioration is relatively small, preparation of a replacement ultraviolet Only, and when the deterioration further progresses, the ultraviolet photoelectric tube 7 is replaced.

[0017]

Effects of the Invention The present invention, as described above, by determining the degradation of the UV flame sensor when the flame presence signal from the UV flame sensor is output when applying the deterioration determination voltage V _2, the initial mild deterioration , And the ultraviolet photoelectric tube can be replaced before the state of severe deterioration is reached. Therefore, at the time of non-ignition or flame extinction, it is possible to prevent an accident such as outputting an erroneous signal indicating that there is no flame and opening the fuel valve when there is no flame. Further, the deterioration determination voltage V ₂ by stepwise multiple settings applied to UV flame sensor, by stepwise to determine the degree of deterioration of the UV flame sensor based on the output signal from the UV flame sensor,
The response can be selected according to the degree of deterioration of the ultraviolet photoelectric tube. Further, the flame detection voltage V ₁ and the deterioration determination voltage V ₂
Are continuously applied alternately, the determination of the presence or absence of the flame and the determination of the presence or absence of the deterioration can be performed in parallel. Therefore, the deterioration of the ultraviolet photoelectric tube can be always determined during the combustion, and the deterioration can be detected immediately when the deterioration occurs.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment in which the present invention is applied to a combustion apparatus.

FIG. 2 is an explanatory diagram showing one embodiment of the present invention.

FIG. 3 is an explanatory view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion device 2 Fuel line 3 Blower 4 Fuel valve 5 Electric motor 6 Controller 7 Ultraviolet photoelectric tube 8 Voltage application means 9 Deterioration judgment means

Claims (6)

[Claims] 1. An ultraviolet photoelectric tube 7 in a state where a flame is present.
The deterioration determination voltage V lower than the discharge start voltage V ₀ at the time of non-deterioration
₂ is applied, when the flame presence signal is output during this degradation determination voltage V ₂ applied, the deterioration determination method for UV flame sensor, characterized by determining the degradation of the UV flame sensor 7. 2. A deterioration determination method for UV flame sensor of claim 1, wherein the deterioration determination of the voltage V ₂ by stepwise multiple settings applied to UV flame sensor 7, based on an output signal from the UV flame sensor 7 And determining the degree of deterioration of the ultraviolet photoelectric tube 7 step by step. 3. A state in which the flame is present, applied to the UV flame sensor 7 undegraded during the discharge starting voltage and high flame detection voltages V ₁ from V ₀ and the discharge starting voltage lower deterioration determination voltage V ₂ than V ₀ alternately and, when the flame presence signal when the deterioration determination voltage V ₂ applied is outputted, the deterioration determination method for UV flame sensor, characterized by determining the degradation of the UV flame sensor 7. 4. An ultraviolet photoelectric tube 7 and the ultraviolet photoelectric tube 7
The deterioration determination voltage V lower than the discharge start voltage V ₀ at the time of no deterioration
₂ , a voltage application means 8 for applying the voltage ₂
A deterioration judging device for an ultraviolet photoelectric tube, comprising: a deterioration judging means 9 for judging deterioration of the ultraviolet photoelectric tube 7 when a flame presence signal is output at the time of application. 5. A deterioration determination device of the UV flame sensor of claim 4, wherein the voltage applying means 8, have the function of applying the deterioration determination voltage V ₂ UV flame sensor 7 by stepwise configure several A deterioration judging device for the ultraviolet phototube, wherein the deterioration judging means has a function of judging a degree of deterioration of the ultraviolet phototube based on an output signal from the ultraviolet phototube. 6. An ultraviolet photoelectric tube 7, and the ultraviolet photoelectric tube 7
The flame detection voltage V ₁ higher than the discharge start voltage V ₀ at the time of non-deterioration
And voltage applying means 8 for applying alternately a low deterioration determination voltage V ₂ than the discharge start voltage V ₀ and the deterioration determination voltage V ₂
A deterioration judging device for an ultraviolet photoelectric tube, comprising: a deterioration judging means 9 for judging deterioration of the ultraviolet photoelectric tube 7 when a flame presence signal is output at the time of application.