JP7232104B2 - Flame detection system and fault diagnosis method - Google Patents

Description

The present invention relates to a flame detection system for detecting the presence or absence of flame.

A UV (ultraviolet) sensor is known as a flame sensor for detecting the presence or absence of flame in a combustion furnace or the like. In a conventional UV sensor that uses the discharge principle, when ultraviolet rays from a flame hit an electrode, discharge occurs and discharge current flows. This discharge current is integrated, converted into a voltage output, and the resulting voltage is displayed as a frame voltage (see, for example, Patent Document 1). The discharge cycle of the UV sensor depends on the frequency of the power supply voltage, and when the frequency is 50 Hz, discharge is performed up to 50 times per second. One discharge is performed for a period of several milliseconds, and the discharge current has a pulse-like waveform. Therefore, in order to convert the discharge current into a voltage, integration is performed using a filter. As a result, the frame voltage rise time constant and fall time constant increase.

FIG. 12 is a diagram showing waveforms of the discharge current of the UV sensor and the frame voltage obtained by integrating the discharge current. Note that FIG. 12 also describes the opening and closing operation of the shutter arranged between the flame and the UV sensor.
It takes about 4 to 5 seconds for the flame voltage to rise and fall, which is slower than the time (frame response) from when the flame disappears until the output is turned off. Even if the level of ultraviolet rays can be determined, abrupt changes in the ultraviolet rays from the flame cannot be captured, making it difficult to determine whether or not the UV sensor has failed.

In addition, since the voltage applied to the UV sensor is generated from the commercial power supply voltage, the discharge current increases or decreases depending on the level of the power supply voltage. Therefore, even if the discharge is performed 50 times per second, there is a possibility that the same frame voltage will not always be obtained. The example of FIG. 13 is a diagram showing the waveforms of the discharge current of the UV sensor and the frame voltage when the power supply voltage is 100% and when it rises to 110%. In FIG. 13, I1 is the discharge current when the power supply voltage is 100%, I2 is the discharge current when the power supply voltage is increased to 110%, V1 is the frame voltage when the power supply voltage is 100%, and V2 is the power supply voltage. It is the frame voltage when it rises to 110%.

As described above, the frame voltage is obtained by integrating the discharge current with the integrating circuit. Therefore, it is difficult to detect changes in the discharge with the conventional method of monitoring the frame voltage. Furthermore, as described with reference to FIG. 13, the frame voltage is also affected by fluctuations in the power supply voltage. Therefore, even if there is a change in the discharge current, for example, as shown at C in FIG. 14, the change in the frame voltage due to the change in the discharge current may be due to the failure of the UV sensor or the lens of the UV sensor. There was a problem that it was difficult to determine whether it was caused by contamination or by fluctuations in the power supply voltage. Further, in the case of a flame detection system with a shutter mechanism, opening and closing of the shutter causes a large fluctuation in the flame voltage, which makes it more difficult to determine the cause of the fluctuation in the flame voltage.

JP-A-2005-83605

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems. The purpose is to provide a diagnostic method.

A flame detection system according to the present invention includes a flame sensor configured to detect ultraviolet rays generated from a flame, an applied voltage generator configured to periodically apply a drive voltage to electrodes of the flame sensor, and a discharge detection unit configured to detect a discharge of a flame sensor; a discharge counting unit configured to count the number of discharges detected by the discharge detection unit;
a discharge probability calculation unit configured to calculate a discharge probability based on the number of times the driving voltage is applied and the number of discharges counted by the discharge counting unit; a storage unit configured to store in advance for each combustion condition of a device that generates the discharge; and acquiring from the storage unit the reference value corresponding to the combustion condition when the discharge probability is calculated by the discharge probability calculation unit. and a failure determination unit configured to determine whether or not an abnormality has occurred in the flame detection system by comparing the reference value with the discharge probability calculated by the discharge probability calculation unit. It is characterized.

Further, one configuration example of the flame detection system of the present invention includes light shielding means provided between the flame and the flame sensor, and opening and closing the light shielding means to switch the flame sensor to a state in which light is shielded and the state in which the light is shielded. a shutter control unit configured to switch between a state in which the flame sensor can receive light and a state in which the flame sensor can receive light; It is characterized in that whether or not an abnormality has occurred in the flame detection system is determined by comparing the probability with the reference value acquired from the storage unit.

Further, in one configuration example of the flame detection system of the present invention, a discharge current detection unit configured to detect the discharge current of the flame sensor, and the presence or absence of discharge of the flame sensor based on the level of the discharge current. and a level determination circuit configured to determine whether the shutter control unit closes the light blocking means when the level determination circuit determines that the discharge of the flame sensor has occurred, and the discharge of the flame sensor The light shielding means is opened when the level determination circuit determines that the light has stopped.
Further, in one configuration example of the flame detection system of the present invention, the failure determination unit acquires the reference value corresponding to the current combustion condition from the storage unit.

A flame detection system failure diagnosis method of the present invention comprises a first step of periodically applying a driving voltage to an electrode of a flame sensor for detecting ultraviolet rays generated from a flame; a third step of calculating a discharge probability based on the number of times the drive voltage is applied and the number of times of discharge detected in the second step; referring to a storage unit stored in advance for each combustion condition of the equipment to be operated, acquiring from the storage unit the reference value corresponding to the combustion condition when the discharge probability is calculated in the third step, and using the reference value as and a fourth step of determining whether or not an abnormality has occurred in the flame detection system by comparing the discharge probability calculated in the third step.

In one configuration example of the flame detection system failure diagnosis method of the present invention, a light shielding means provided between the flame and the flame sensor is controlled to control the state in which the flame sensor is shielded and the state in which the flame sensor is shielded. and a state in which the light can be received, wherein the fourth step includes the discharge probability calculated in the third step when the flame sensor is in a state in which light can be received, and the discharge probability obtained from the storage unit. It is characterized by including a step of determining whether an abnormality has occurred in the flame detection system by comparing with the reference value obtained.

According to the present invention, a storage section for pre-storing a reference value of the discharge probability for each combustion condition of a device that generates a flame and a failure determination section are provided, and the failure determination section calculates the discharge probability by the discharge probability calculation section. A reference value corresponding to the combustion condition when the flame sensor is fired is acquired from the storage unit, and by comparing this reference value with the discharge probability calculated by the discharge probability calculation unit, subtle fluctuations of the flame sensor can be captured. Therefore, it is possible to determine whether or not an abnormality has occurred in the flame detection system almost without being affected by fluctuations in the power supply voltage.

Further, in the present invention, a storage section for pre-storing a reference value for the number of discharges for each combustion condition of a device that generates a flame, and a failure determination section are provided, and the failure determination section determines the number of discharges by the discharge determination section. A reference value corresponding to the combustion condition at the time of detection is obtained from the storage unit, and by comparing this reference value with the number of discharges detected by the discharge determination unit, subtle fluctuations of the flame sensor are captured. Therefore, it is possible to determine whether or not an abnormality has occurred in the flame detection system almost without being affected by fluctuations in the power supply voltage.

Further, in the present invention, a storage unit and a failure determination unit are provided, and the discharge probability calculated by the discharge probability calculation unit when the flame sensor is in a state in which daylight can be received is compared with the reference value obtained from the storage unit. , subtle fluctuations of the flame sensor can be captured, and whether or not an abnormality has occurred in the flame detection system can be determined almost without being affected by fluctuations in the power supply voltage and the opening and closing of the light shielding means.

Further, in the present invention, a storage unit and a failure determination unit are provided, and the number of discharges detected by the discharge determination unit when the flame sensor is in a state in which light can be received is compared with the reference value obtained from the storage unit. , subtle fluctuations of the flame sensor can be captured, and whether or not an abnormality has occurred in the flame detection system can be determined almost without being affected by fluctuations in the power supply voltage and the opening and closing of the light shielding means.

FIG. 1 is a block diagram showing the configuration of a flame detection system according to a first embodiment of the invention. FIG. 2 is a flow chart illustrating the operation of the flame detection system according to the first embodiment of the invention. FIG. 3 is a diagram showing the discharge current, frame voltage, and discharge probability of the UV sensor during normal operation in the first embodiment of the present invention. FIG. 4 is a diagram showing the discharge current, frame voltage, and discharge probability of the UV sensor during an abnormality in the first embodiment of the present invention. FIG. 5 is a flowchart illustrating another operation of the flame detection system according to the first embodiment of the invention. FIG. 6 is a block diagram showing the configuration of a flame detection system according to a second embodiment of the invention. FIG. 7 is a flow chart illustrating the operation of the flame detection system according to the second embodiment of the invention. FIG. 8 is a diagram showing the discharge current, frame voltage, and discharge probability of the UV sensor during normal operation in the second embodiment of the present invention. FIG. 9 is a diagram showing the discharge current, frame voltage, and discharge probability of the UV sensor during an abnormality in the second embodiment of the present invention. FIG. 10 is a flowchart illustrating another operation of the flame detection system according to the second embodiment of the invention. FIG. 11 is a block diagram showing an example configuration of a computer that implements the flame detection system according to the first and second embodiments of the present invention. FIG. 12 is a diagram showing waveforms of the discharge current and the frame voltage of the UV sensor. FIG. 13 is a diagram showing waveforms of the discharge current of the UV sensor and the frame voltage when the power supply voltage is 100% and when it rises to 110%. FIG. 14 is a diagram showing the waveform of the frame voltage when the discharge current of the UV sensor changes.

[Principle of Invention]
The present invention focuses on the discharge probability of the UV sensor. Specifically, the discharge probability is obtained by counting the number of times of discharge per unit time. For example, the number of discharges per second is 50 times when the frequency of the power supply voltage is 50 Hz, and 60 times when the frequency of the power supply voltage is 60 Hz, based on the driving principle of the UV sensor. Here, if there are 50 discharge opportunities per second and the UV sensor discharges each time, the probability of discharge per second is 50/50=100%. Also, if the UV sensor discharges 25 times, the discharge probability per second is 25/50=50%. That is, if N is the number of discharge opportunities per second and n is the number of discharges per second, the discharge probability P per second is given by the following equation.
P=n/N×100 (1)

This discharge probability P is used as a parameter for monitoring the output of the UV sensor instead of the flame voltage. Since the discharge probability P is not affected by fluctuations in the power supply voltage, the pure discharge state is reflected, even subtle changes in the discharge can be detected, and the state of the flame can be confirmed with good responsiveness. .

In addition, in the present invention, it is possible to separately count the number of discharges (discharge probability) while the shutter is open and while the shutter is closed. By comparing the calculated discharge probability with the normal discharge probability, it becomes possible to detect the occurrence of an abnormality such as contamination of the UV sensor. In the case of the frame voltage, it is difficult to discern the change, and even if the UV sensor is contaminated, there is a high possibility that the abnormality of the UV sensor cannot be detected until a clear abnormality such as a misfire is issued. According to the present invention, by monitoring the discharge probability, an abnormality of the flame detection system can be detected before an abnormality alarm is issued, and maintenance of the flame detection system can be performed.

[First embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a flame detection system according to a first embodiment of the invention. The flame detection system includes a UV sensor 1 (UV phototube) that serves as a flame sensor for detecting light (ultraviolet rays) generated from a flame 100, a power supply circuit 2 that supplies power supply voltage, and a pair of electrodes of the UV sensor 1 with a driving voltage. an applied voltage generation unit 3 for periodically applying , a discharge detection unit 4 for detecting discharge of the UV sensor 1, a discharge counting unit 5 for counting the number of discharges detected by the discharge detection unit 4, and a drive a discharge probability calculation unit 8 for calculating the discharge probability based on the number of voltage application times and the number of discharge times; an ultraviolet intensity determination unit 6 for determining the ultraviolet intensity based on the discharge probability obtained by the discharge probability calculation unit 8; A determination result output unit 7 that outputs the ultraviolet intensity determined by the intensity determination unit 6, a storage unit 9 that stores in advance the reference value of the discharge probability for each combustion condition of the equipment that generates the flame, and an ultraviolet intensity determination unit 6. A reference value corresponding to the combustion condition when the discharge probability determined by is calculated is obtained from the storage unit 9, and by comparing this reference value with the discharge probability calculated by the discharge probability calculation unit 8, the flame A failure determination unit 12 that determines whether an abnormality has occurred in the detection system, a determination result output unit 13 that outputs the determination result of the failure determination unit 12, and a discharge current detection unit 10 that detects the discharge current of the UV sensor 1. , a level determination circuit 11 for determining the level of the discharge current detected by the discharge current detection unit 10, and a flame signal input unit 20 for inputting the value determined by the level determination circuit 11 as a flame signal.

FIG. 2 is a flow chart for explaining the operation of the flame detection system of this embodiment. The UV sensor 1 includes a cylindrical envelope closed at both ends, two electrode pins passing through the envelope, and two electrodes supported parallel to each other by the electrode pins inside the envelope. It consists of a phototube with electrodes. In such a UV sensor 1, when a predetermined voltage is applied between the electrodes via the electrode support pins, when one of the electrodes facing the flame 100 is irradiated with ultraviolet rays, the photoelectric effect causes the ultraviolet rays to travel from the electrodes. Electrons are emitted and a discharge current flows between the electrodes.

The power supply circuit 2 supplies an externally input commercial power supply voltage to the applied voltage generator 3 . At the start of the flame detection operation, the discharge count unit 5 initializes the number of times n of discharges to 0 (step S100 in FIG. 2), and the discharge probability calculation unit 8 initializes the number of times N of application of the drive voltage to 0 (step S101 in FIG. 2). ).

The applied voltage generator 3 boosts the AC voltage supplied from the power supply circuit 2 to a predetermined value and applies it between the pair of terminals 110 and 111 of the UV sensor 1 .
A discharge detector 4 detects a discharge current flowing through the UV sensor 1 . For example, a light-emitting diode and a phototransistor are provided in the discharge detection unit 4, and the light from the light-emitting diode driven by the discharge current flowing through the UV sensor 1 is detected through the phototransistor (step S102 in FIG. 2).
When the discharge detection unit 4 detects the discharge current, the discharge count unit 5 increases the number of times of discharge n by 1 (step S103 in FIG. 2).

In this way, the processes of steps S102 and S103 are repeatedly executed. When the number of times N (discharge opportunity) of driving voltage application reaches a predetermined number Nth (for example, 50 times in this embodiment) (YES in step S104 in FIG. 2), the discharge probability calculation unit 8 calculates the discharge probability according to the equation (1). P is calculated (step S105 in FIG. 3).

After calculating the discharge probability P, the discharge counting unit 5 initializes the number of times of discharge n to 0 (step S106 in FIG. 2), and the discharge probability calculation unit 8 initializes the number of times N of driving voltage application to 0 (step S107 in FIG. 2). ).

Next, in the storage unit 9, when the UV sensor 1 is normal, the discharge probability Pref (reference value) when the number of times N of application of the driving voltage reaches the predetermined number Nth is stored as the combustion of the equipment that generates the flame 100. It is stored in advance for each condition.

When the failure determination unit 12 is in a combustion condition for which failure diagnosis should be performed (YES in step S108 in FIG. 2), the failure determination unit 12 acquires the value of the discharge probability Pref corresponding to the combustion condition from the storage unit 9 (step S109 in FIG. 2). . The failure determination unit 12 then compares the acquired discharge probability Pref with the discharge probability P calculated by the discharge probability calculation unit 8 to determine whether an abnormality has occurred in the flame detection system (see FIG. 2). step S110).

When the absolute value |Pref-P| of the difference between the discharge probability Pref and the discharge probability P exceeds a predetermined threshold value Pth (YES in step S110), failure determination unit 12 determines that an abnormality has occurred in the flame detection system. Determine (step S111 in FIG. 2). Further, when the absolute value |Pref−P| of the difference between the discharge probability Pref and the discharge probability P is equal to or less than the threshold value Pth (NO in step S110), the failure determination unit 12 determines that the flame detection system is normal (FIG. 2 step S112).

The determination result output unit 13 outputs the determination result of the failure determination unit 12 to the outside (step S114 in FIG. 2). Methods for outputting the determination result include, for example, displaying the content of the determination result, transmitting the information indicating the determination result to the outside, and reading the information from the outside.

Thus, in this embodiment, by comparing the discharge probability Pref and the discharge probability P under the same combustion condition, it is possible to determine whether or not an abnormality has occurred in the flame detection system, almost without being affected by fluctuations in the power supply voltage. can judge.

FIG. 3 shows the discharge current, frame voltage, and discharge probability P of the UV sensor 1 during normal operation, and FIG. 4 shows the discharge current, frame voltage, and discharge probability P of the UV sensor 1 during abnormal operation. In the example of FIG. 4, it can be seen that due to the occurrence of an abnormal discharge as indicated by A, the discharge probability P becomes a different value from the discharge probability P in the normal state.

In the example of FIG. 2, it is determined whether or not the flame detection system is abnormal based on the discharge probability P, but it is determined whether or not the flame detection system is abnormal based on the number of discharges n You may make it judge. When determining whether or not the flame detection system is abnormal based on the number of discharges n, the discharge probability calculator 8 is unnecessary. FIG. 5 shows the operation of the flame detection system in this case. The processes of steps S100 to S104 and S106 to S108 in FIG. 5 are as explained in FIG.

Here, when the UV sensor 1 is normal, the discharge frequency nref (reference value) when the driving voltage application frequency N reaches the predetermined number Nth is stored in the storage unit 9 as the combustion frequency of the device that generates the flame 100. It is stored in advance for each condition.

When the current combustion condition is a condition for failure diagnosis (YES in step S108 in FIG. 5), the failure determination unit 12 acquires the value of the number of times of discharge nref corresponding to this combustion condition from the storage unit 9 (step S108 in FIG. 5). S109a). Then, the failure determination unit 12 determines whether or not an abnormality has occurred in the flame detection system by comparing the acquired number of discharges nref with the number of discharges n counted by the discharge counting unit 5 (step 5 in FIG. 5). S110a).

When the absolute value |nref−n| of the difference between the number of discharges nref and the number of discharges n exceeds a predetermined threshold value nth (YES in step S110a), failure determination unit 12 determines that an abnormality has occurred in the flame detection system. Determine (step S111 in FIG. 5). Further, when the absolute value |nref−n| of the difference between the number of discharges nref and the number of discharges n is equal to or smaller than the threshold value nth (NO in step S110a), the failure determination unit 12 determines that the flame detection system is normal (FIG. 5). step S112). The process of step S113 in FIG. 5 is as explained in FIG.

[Second embodiment]
In the first embodiment, an example of a flame detection system without a shutter mechanism is described, but the present invention can also be applied to a flame detection system with a shutter mechanism. FIG. 6 is a block diagram showing the configuration of a flame detection system according to a second embodiment of the present invention, and the same components as in FIG. 1 are given the same reference numerals.

The flame detection system of this embodiment includes a UV sensor 1, a power supply circuit 2, an applied voltage generation unit 3, a discharge detection unit 4, a discharge count unit 5, an ultraviolet intensity determination unit 6, and a determination result output unit 7. , the discharge probability calculation unit 8a, the discharge current detection unit 10, the level determination unit 11, the flame signal input unit 20, the storage unit 9, and the discharge probability calculation unit 8a when the UV sensor 1 is in a state where daylight is available. a failure determination unit 12a that determines whether or not an abnormality has occurred in the flame detection system by comparing the calculated discharge probability with a reference value acquired from the storage unit 9; a determination result output unit 13; and the UV sensor 1; The shutter 15 and the shutter driving section 16 constitute light shielding means.

FIG. 7 is a flowchart for explaining the operation of the flame detection system of this embodiment. The shutter control unit 17 outputs a shutter open signal and a shutter close signal for opening and closing the shutter 15 . The shutter control unit 17 closes the shutter 15 when it determines that the discharge of the UV sensor 1 has occurred based on the output determined by the level determination circuit 11, and closes the shutter 15 when it determines that the discharge of the UV sensor 1 has stopped. Open 15.

Specifically, the level determination circuit 11 determines that the discharge of the UV sensor 1 occurs when the voltage indicating the discharge current of the UV sensor 1 exceeds a predetermined discharge threshold value Ith1, and controls the shutter based on the determination result. A unit 17 outputs a shutter close signal. Further, the level determination circuit 11 determines that the discharge of the UV sensor 1 has stopped because the voltage indicating the discharge current of the UV sensor 1 has fallen below a predetermined discharge stop threshold value Ith2 (Ith1>Ith2). outputs a shutter open signal. Thus, the shutter 15 repeats opening and closing operations.

In order to avoid frequent opening and closing of the shutter 15, the voltage to be compared with the discharge threshold value Ith1 and the discharge stop threshold value Ith2 is not the output voltage itself of the discharge current detection unit 10, but is subjected to, for example, an integration process. The waveform has a blunted rise and fall. That is, the level determination circuit 11 converts the voltage waveform into a voltage waveform having a predetermined time constant, compares it with the discharge threshold Ith1 and the discharge stop threshold Ith2, and the shutter control unit 17 outputs a shutter open/close signal based on the output.

The processes of steps S200 and S201 in FIG. 7 are the same as steps S100 and S101 in FIG.
The shutter drive unit 16 opens the shutter 15 when the shutter open signal is output from the shutter control unit 17 (step S202 in FIG. 7). By opening the shutter 15, the UV sensor 1 becomes ready for daylighting.

The processes of steps S203 to S209 in FIG. 7 are the same as steps S102 to S108 in FIG. In FIG. 7, the processing of steps S203 to S204 is described to clarify the operation. , the discharge of the UV sensor 1 is always detected during the operation of the flame detection system, and the discharge counter 5 always detects the discharge of the UV sensor 1 during the operation of the flame detection system.

In this embodiment, the storage unit 9 stores the discharge probability Pref (reference value) when the number of times N of application of the drive voltage reaches the predetermined number Nth when the UV sensor 1 is normal and can receive light. 100 is stored in advance for each combustion condition of the equipment that generates 100.

When a shutter open signal is output from the shutter control unit 17, the shutter 15 is open, and the combustion condition is such that failure diagnosis should be executed (YES in step S209 in FIG. 7), the failure determination unit 12a determines whether the combustion condition is met. The value of the corresponding discharge probability Pref is obtained from the storage unit 9 (step S210 in FIG. 7).

The failure determination unit 12a then compares the acquired discharge probability Pref with the discharge probability P calculated by the discharge probability calculation unit 8 to determine whether an abnormality has occurred in the flame detection system (see FIG. 7). step S211). The processing of steps S212 to S214 in FIG. 7 is the same as steps S111 to S113 in FIG.

Next, when the shutter control unit 17 determines that the discharge of the UV sensor 1 has occurred (YES in step S215 in FIG. 7), it outputs a shutter close signal. The shutter drive unit 16 closes the shutter 15 when the shutter close signal is output from the shutter control unit 17 (step S216 in FIG. 7). As a result, the ultraviolet rays from the flame 100 are blocked by the shutter 15 and the incidence of the ultraviolet rays on the UV sensor 1 is blocked.

When the shutter close signal is output from the shutter control unit 17, the discharge probability calculation unit 8a holds the value of the discharge probability P calculated immediately before until the next time the shutter 15 is opened and the discharge probability P is newly calculated. (step S217 in FIG. 7).

Next, when the shutter controller 17 determines that the discharge of the UV sensor 1 has stopped (YES in step S218 in FIG. 7), it outputs a shutter open signal. The shutter drive unit 16 opens the shutter 15 when the shutter open signal is output from the shutter control unit 17 (step S202 in FIG. 7).

Thus, in this embodiment, the same effect as in the first embodiment can be obtained in the flame detection system with the shutter mechanism.
FIG. 8 is a diagram showing the discharge current, frame voltage, and discharge probability P of the UV sensor 1 during normal operation, and FIG. 9 is a diagram showing the discharge current, frame voltage, and discharge probability P of the UV sensor 1 during abnormal operation. 13, I1 is the discharge current when the power supply voltage is 100%, I2 is the discharge current when the power supply voltage is increased to 110%, V1 is the frame voltage when the power supply voltage is 100%, and V2 is the power supply voltage. Frame voltage when the voltage is increased to 110%. P' in FIGS. 8 and 9 indicates the discharge probability P only when the shutter is open. In the example shown in FIG. 9, it can be seen that the discharge probability P becomes different from the discharge probability P in the normal state due to the occurrence of an abnormal discharge as indicated by B.

Also in this embodiment, it may be determined whether or not an abnormality has occurred in the flame detection system based on the number of discharges n. When determining whether or not an abnormality has occurred in the flame detection system based on the number of discharges n, the discharge probability calculator 8a is unnecessary. FIG. 10 shows the operation of the flame detection system in this case. The processes of steps S200 to S205, S207, and S208 in FIG. 10 are as explained in FIG.

Here, in the storage unit 9, when the UV sensor 1 is normal and daylighting is possible, the discharge number nref (reference value) when the drive voltage application number N reaches a predetermined number Nth is stored. It is stored in advance for each combustion condition of the device that generates it.

When a shutter open signal is output from the shutter control unit 17, the shutter 15 is open, and the combustion condition is such that failure diagnosis should be executed (YES in step S209 in FIG. 10), the failure determination unit 12a determines whether the combustion condition is met. The value of the corresponding number of discharges nref is obtained from the storage unit 9 (step S210a in FIG. 10).

Then, the failure determination unit 12a determines whether or not an abnormality has occurred in the flame detection system by comparing the acquired number of discharges nref with the number of discharges n counted by the discharge determination unit 6 (step 10 in FIG. 10). S211a). The processes of steps S212 to S214 in FIG. 10 are the same as steps S111 to S113 in FIG. 10 are as described with reference to FIG.

In the first and second embodiments, the storage unit 9 stores the discharge probability Pref or the number of discharges nref when the flame detection system is normal as the reference value of the discharge probability P or the number of discharges n. However, the discharge probability P or the number of discharges n at the initial stage of operation of the flame detection system may be stored as a reference value, or the previously calculated discharge probability P or the number of discharges n may be stored.

In this case, the discharge probability calculation units 8 and 8a store the value of the discharge probability P calculated at the beginning of the operation of the flame detection system or at the previous calculation in the storage unit 9 together with the combustion condition information at the time of the initial calculation or the previous calculation. Alternatively, the discharge counting unit 5 causes the storage unit 9 to store the value of the number of discharges n at the beginning of operation or at the previous calculation together with the combustion condition information input at the beginning of operation or at the time of the previous calculation.

In addition, as a technique for estimating the progress of deterioration of the UV sensor up to the present, assuming that the discharge probability of the UV sensor is used as a deterioration index and that the discharge probability decreases in the long term, Japanese Patent Application Laid-Open No. 2018-205162 discloses. Although the disclosed technology exists, this technology cannot be applied to abnormality diagnosis in a short period (every judgment cycle).

Discharge detection unit 4, discharge count unit 5, ultraviolet intensity determination unit 6, determination result output unit 7, discharge probability calculation units 8a, 8a, storage unit 9, and discharge current detection unit 10 described in the first and second embodiments , the level determination circuit 11, the failure determination units 12 and 12a, the determination result output unit 13, and the shutter control unit 17 are implemented by a CPU (Central Processing Unit), a computer equipped with an interface, and a program that controls these hardware resources. can be realized.

A configuration example of this computer is shown in FIG. The computer includes a CPU 200 and an interface device (hereinafter abbreviated as I/F) 201 . The I/F 201 is connected to the discharge detection unit 4 (discharge detection circuit), the fixed result output unit 7 (communication circuit, display circuit, etc.) and the like. In such a computer, a program for implementing the fault diagnosis method of the present invention is stored in the internal memory of the CPU 200 . The CPU 200 executes the processes described in the first and second embodiments according to programs stored in the memory.

The invention can be applied to flame detection systems.

DESCRIPTION OF SYMBOLS 1... UV sensor, 2... Power supply circuit, 3... Applied voltage generation part, 4... Discharge detection part, 5... Discharge counting part, 6... Ultraviolet intensity determination part, 7... Confirmation result output part, 8, 8a... Discharge probability calculation Section 9 Storage section 10 Discharge current detection section 11 Level determination circuit 12, 12a Failure determination section 13 Determination result output section 15 Shutter 16 Shutter drive section 17 Shutter control section , 20 . . . flame signal input section.

Claims (6)

a flame sensor configured to detect ultraviolet radiation from a flame;
an applied voltage generator configured to periodically apply a drive voltage to the electrodes of the flame sensor;
a discharge detector configured to detect discharge of the flame sensor;
a discharge counting unit configured to count the number of discharges detected by the discharge detection unit;
a discharge probability calculation unit configured to calculate a discharge probability based on the number of times the driving voltage is applied and the number of discharges counted by the discharge counting unit;
a storage unit configured to store in advance the reference value of the discharge probability for each combustion condition of the device that generates the flame;
The reference value corresponding to the combustion condition when the discharge probability calculation unit calculates the discharge probability is obtained from the storage unit, and the reference value and the discharge probability calculated by the discharge probability calculation unit are compared. and a failure determination unit configured to determine whether an abnormality has occurred in the flame detection system. The flame detection system of claim 1, wherein
a light blocking means provided between the flame and the flame sensor;
a shutter control unit configured to open and close the light shielding means to switch between a state in which the flame sensor is shielded from light and a state in which the flame sensor can receive light;
The failure determination unit compares the discharge probability calculated by the discharge probability calculation unit when the flame sensor is in a state in which daylight can be received and the reference value obtained from the storage unit, thereby determining whether there is an abnormality in the flame detection system. A flame detection system characterized by determining whether or not a flame is occurring. 3. The flame detection system of claim 2 , wherein
a discharge current detector configured to detect a discharge current of the flame sensor;
a level determination circuit configured to determine whether or not the flame sensor discharges based on the level of the discharge current;
The shutter control section closes the light blocking means when the level determination circuit determines that the discharge of the flame sensor has occurred, and closes the light blocking means when the level determination circuit determines that the discharge of the flame sensor has stopped. A flame detection system characterized by opening means. A flame detection system according to any one of claims 1 to 3 ,
The flame detection system, wherein the failure determination section acquires the reference value corresponding to the current combustion condition from the storage section. a first step of periodically applying a driving voltage to electrodes of a flame sensor that detects ultraviolet light emitted from a flame;
a second step of detecting discharge of the flame sensor;
a third step of calculating a discharge probability based on the number of times the drive voltage is applied and the number of times of discharge detected in the second step;
The reference value of the discharge probability is stored in advance for each combustion condition of the device that generates the flame, and the reference value corresponding to the combustion condition when the discharge probability is calculated in the third step is obtained. and a fourth step of determining whether or not an abnormality has occurred in the flame detection system by comparing the reference value obtained from the storage unit and the discharge probability calculated in the third step. A method for diagnosing a flame detection system. In the flame detection system failure diagnosis method according to claim 5 ,
further comprising a fifth step of controlling light shielding means provided between the flame and the flame sensor to switch between a state in which the flame sensor is shielded from light and a state in which the flame sensor can receive light;
The fourth step compares the discharge probability calculated in the third step with the reference value obtained from the storage unit when the flame sensor is in a state in which daylight can be received, thereby determining whether there is an abnormality in the flame detection system. A method for diagnosing a failure of a flame detection system, comprising the step of determining whether a flame detection system has occurred.

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