JP4645987B2 - Flame detection device - Google Patents

Description

  The present invention relates to a flame detection device for detecting a flame, and more particularly to a flame detection device for detecting a flame from a burner in a combustion device.

  A combustion detector such as a boiler is provided with a flame detection device for monitoring the flame from the burner. As such a flame detection device, one that detects an abnormality of the flame detection device based on a signal from a flame detection sensor is known.

  For example, the flame detection device described in Patent Document 1 uses an ultraviolet phototube as a flame detection sensor, measures the number of discharge pulses per fixed time, and if it is within a normal range, the flame detection device is normal. If it is determined that it is not within the normal range, it is determined that the flame detection device is abnormal.

JP-A-10-267273

In the invention described in Patent Document 1, the number of discharge pulses output from the flame detection sensor within a predetermined time is measured, and the presence or absence of abnormality of the flame detection device is determined based on this number. However, in an actual flame detection device, it may not be possible to detect an abnormality only by the number of discharge pulses in a certain time. Specifically, even if an abnormality occurs in each device such as a drive circuit constituting the flame detection device and an abnormal pulse signal is generated, the number of discharge pulses within a certain time is within the normal number range. If it falls within the range, it may not be possible to detect an abnormality. In particular, in the invention described in Patent Document 1 using an ultraviolet phototube, a discharge pulse is generated by background noise even when no flame is present, and the lower limit of the normal range of the discharge pulse within a certain time is expanded to zero. Therefore, the presence / absence of abnormality is determined only by whether the number of discharge pulses is larger or smaller than the predetermined number, and the detection accuracy further decreases.

  The object of the present invention is to solve such problems of the prior art. Specifically, it is an object to make it possible to more reliably detect the presence or absence of an abnormality in a flame detection device.

The present invention has been made to solve the above problems, and the invention according to claim 1 is a flame detection sensor, and a pulse converter for applying a pulse of a constant frequency to the flame detection sensor, A plurality of detection means for detecting the presence / absence of an abnormality according to a pulse generation form output from the flame detection sensor, and the detection means detects the presence / absence of an abnormality based on any one of the pulse generation forms First detecting means for detecting the presence or absence of abnormality based on any one of the generation modes of the pulses, and the first detecting means for detecting a predetermined time from the flame detecting sensor. The number of the pulses is measured to detect the presence / absence of abnormality, and the second detection means detects the presence / absence of abnormality based on the width of the pulse .

The invention according to claim 2 is a flame detection sensor, a pulse converter for applying a pulse of a constant frequency to the flame detection sensor, and converting an output signal of the flame detection sensor into a pulse, and the flame detection A plurality of detection means for detecting presence / absence of abnormality by detecting two or more kinds of different generation forms among the generation forms such as the number, width, amplitude, etc. of the pulses output from the sensor within a certain time. It is a feature.

According to the third aspect of the present invention, there is provided one flame detection sensor composed of an ultraviolet photoelectric tube configured not to pass an electric current when there is no flame, but to pass an electric current when there is a flame, and a constant to the flame detection sensor. A pulse converter for applying a frequency pulse to synchronize with the current and converting the output signal of the flame detection sensor into a pulse, and the number, width, amplitude, etc. of the pulse output from the flame detection sensor within a certain time A plurality of detection means for detecting the presence or absence of abnormality by detecting two or more types of different generation forms.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the plurality of detection means measure the number of the pulses per predetermined time from the flame detection sensor, and whether or not there is an abnormality. And a second detection means for detecting the presence / absence of an abnormality based on the width of the pulse.

The invention according to claim 5 is the invention according to claim 4 , wherein at least one of the detection means detects an abnormality in response to a signal from the first detection means and the second detection means. The flame detection device includes a determination unit that determines that there is an abnormality.

According to the present invention, it is possible to more reliably detect whether there is an abnormality in the flame detection device.

(Embodiment)
An embodiment of the present invention will be described. In this embodiment, one flame detection sensor, a pulse conversion device that applies a pulse of a constant frequency to the flame detection sensor, and an abnormality of the flame detection device depending on the generation form of the pulses output from the flame detection sensor. Detecting means for detecting the presence or absence of.

  This embodiment is particularly applied to a combustion apparatus such as a boiler, and is used to detect an abnormality in the flame detection apparatus including the pulse converter, the other detection means, and other devices.

  Next, components of this embodiment will be described. The flame detection sensor includes an ultraviolet photoelectric tube, a CdS (cadmium sulfide) photoconductive cell, a CdSe (cadmium selenide) photoconductive cell, a PbS photoconductive cell (red sulfide cell), a frame rod, a photo IC, a photodiode, a solar cell, and the like. The sensor comprised using can be illustrated. Which of these flame detection elements is used as a flame detection sensor is appropriately selected according to the nature of the flame due to the difference in the emission spectrum, the type of fuel that produces the flame (gas, oil, etc.), the application, and the like.

  The pulse converter converts an output signal of the flame detection sensor into a pulse, and a pulse can be applied as a power source of the flame detection sensor. The flame detection sensor outputs a pulse by the pulse converter, although different physical changes such as a current value and a resistance value occur depending on the type of each flame detection element. Thereby, highly reliable detection can be enabled. When the pulse converter is used as the power source of the flame detection sensor, the signal sent to the detection means is the same frequency as the pulse generated by the pulse converter when there is a flame, and when there is no flame. In this configuration, no pulse is generated. At this time, in order to detect the strength of the flame, the width and amplitude of the pulse output from the flame detection sensor may be changed according to the strength of the flame. In addition, the threshold value of the flame incident level of the flame detection sensor can be adjusted, and the number of pulses output from the flame detection sensor can be increased or decreased depending on the strength of the flame. In other words, the pulse applied from the pulse converter has a constant frequency, but the number of pulses corresponding to the size of the incident flame can be output by adjusting the threshold value.

  Further, it is also preferable to provide a filter function so that the signal that has passed through this is converted into a pulse signal so as not to be affected by disturbance.

  The pulse generation form is a concept including the number of pulses, the width of the pulses, the amplitude of the pulses, etc. within a certain time.

  The detection means is configured to detect two or more types of different generation forms and determine whether or not the flame detection device has an abnormality. According to this, since a plurality of detections with different viewpoints are performed on the pulse output from the flame detection sensor, it is possible to detect the presence / absence of abnormality of the flame detection device more accurately. In this way, by detecting two or more types of each of the generation modes of the pulse, unlike the simple multiplexing that detects the same type of generation mode, it is possible to detect the presence or absence of abnormality more accurately. It can be carried out. For example, when detecting means for detecting the number of pulses and detecting the presence / absence of an abnormality is multiplexed, since there is only one flame detection sensor, a common signal is input to the pulse converter. It can only suppress significance and erroneous detection due to malfunction of other detection means for measuring the number of pulses. However, if two or more types of detection are performed among the generation modes of the pulse, even if the pulse generation mode is a pulse that is not considered abnormal, it is detected from a different viewpoint. The accuracy of detecting the presence or absence of can be improved. Here, if the pulse width or the pulse amplitude is used, it is possible to detect the presence or absence of an abnormality earlier than when measuring the number of pulses within a certain time.

  Moreover, it is preferable that the said detection means combines detecting the presence or absence of abnormality of the said pulse with software, and detecting with hardware. This is to increase detection accuracy. That is, if all of the detection means are detected by hardware in the same environment, all of the detection means may malfunction due to the same cause of malfunction (for example, humidity, temperature, dust, static electricity, etc.). It is because the nature is high. The same can be said when all of the detection means are detected by software in the same environment. In addition, it is generally considered that detection by hardware is less prone to malfunction than detection by software that causes unexpected runaway, etc., and that detection by software can easily realize fine control. Then, it is preferable to combine detection by software and detection by hardware. That is, the occurrence of malfunction can be suppressed while increasing the detection accuracy.

  Hereinafter, a first embodiment of a flame detection apparatus 1 embodying the present invention will be described in detail with reference to FIGS. FIG. 1 shows a schematic configuration of the flame detection device 1, and FIG. 2 is an explanatory diagram showing abnormality determination by the flame detection device 1.

  As shown in FIG. 1, the flame detection device 1 includes a flame detection sensor 2 including an ultraviolet photoelectric tube 16 (see FIG. 3), a pulse conversion device 3 that applies a pulse having a constant frequency to the flame detection sensor 2, and The detection unit 4 is configured to detect the presence or absence of abnormality based on the pulse.

The detection unit 4 measures the number of pulses per predetermined time from the flame detection sensor 2 and detects the presence or absence of abnormality based on the first detection means 5 that detects the presence or absence of abnormality and the width of the pulse. When the second detection means 6 to detect and signals from the first detection means 5 and the second detection means 6 detect any one of the detection means 5 and 6, the flame detection device 1 includes a determination unit 7 that determines that there is an abnormality. Here, the first detection means 5 is configured by software, and the second detection means 6 is configured by hardware. This
Thereby, it can suppress that said 1st detection means 5 and said 2nd detection means 6 malfunction simultaneously.

  The pulse converter 3 applies the pulse as a power source to the flame detection sensor 2 at a constant frequency (20 Hz / s). The flame detection sensor 2 is configured such that no current flows when there is no flame, but a current flows when there is a flame, and this current and the pulse applied from the pulse converter 3 are synchronized. . Therefore, the output of the flame detection sensor 2 is a pulse having a frequency equal to or lower than a certain frequency (20 Hz / s) of the power source applied to the flame detection sensor 2 by the pulse converter 3.

  The first detection means 5 detects the presence or absence of an abnormality depending on whether or not the number of pulses measured per second is within a normal range. Since the frequency of the power supply applied to the flame detection sensor 2 is 20 Hz / s, when the flame detection sensor 2 detects a flame, 20 pulses are sent to the first detection means 5 per second. When no flame is detected, zero pulses are sent to the first detection means 5. In Example 1, in consideration of background noise of the flame detection sensor 2 and other errors, when 20 + 5 or less per second, that is, when 25 or less pulses are measured per second, It is configured to detect that it is normal. Here, the locations where an abnormality has occurred include the flame detection sensor 2, the pulse conversion device 3, the pulse conversion connection line 9 for connecting the flame detection sensor 2 and the pulse conversion device 3, and the flame detection sensor. 2 and the detection unit connection line 8 connecting the detection unit 4 can be considered.

  The second detection means 6 detects the presence or absence of abnormality based on the width of the pulse output from the flame detection sensor 2. The duty ratio of the pulse is 50%. Since the output frequency from the flame detection sensor 2 is 20 Hz / s, the width of one pulse is 25 msec. The second detection means 6 considers an error and detects that it is normal when it is within the range of 25 ± 5 msec, and detects that it is abnormal when it exceeds the range of 25 ± 5 msec. Here, the flame detection sensor 2, the pulse conversion device 3, the pulse conversion connection line 9, the detection unit connection line 8, and the like are considered as places where an abnormality has occurred. The second detection means 6 is configured not to operate when the flame detection sensor 2 does not detect a flame.

When both the detecting means 5 and 6 detect that an abnormality has occurred, they output an L signal (0V) , and when they detect that no abnormality has occurred, the detecting means 7 outputs an H signal (5V). It is the structure which outputs to each.

  The determination unit 7 receives signals from both the detection means 5 and 6 and determines that there is an abnormality when at least one of the detection means 5 and 6 detects an abnormality. That is, as shown in FIG. 2, the determination unit 7 determines that it is abnormal unless it is determined that both the detection means 5 and 6 are normal.

The determination unit 7 includes an AND gate (not shown) that receives the outputs from the detection means 5 and 6 as inputs. Further, the determination unit 7 is provided with a fuel valve cutoff relay (not shown), and a relay current flows to the fuel valve cutoff relay while the output from the AND gate is an H signal, While the output from the AND gate is an L signal, the relay drive current does not flow to the fuel valve cutoff relay.

According to the first embodiment, since the presence or absence of abnormality is detected based on the number and width of the pulses output from the flame detection sensor 2, detection from different viewpoints can be performed, and the flame detection device 1 The presence or absence of abnormality can be detected more reliably. Further, since the first detection means 5 is configured by software and the second detection means 6 is configured by hardware, the detection accuracy of the presence or absence of abnormality of the flame detection device 1 can be enhanced. Furthermore, since the second detection means 6 can detect the presence or absence of abnormality within 25 + 5 msec at the shortest, the flame detection device 1 is based only on the number of pulses (under the same conditions as in the first embodiment). For example, detection of the presence / absence of an abnormality based on the number of pulses takes 1 second).

  Next, a modification of the first embodiment will be described. In the first embodiment, the number and width of pulses output from the flame detection sensor 2 are targeted for detection. However, as the third detection means, the amplitude of the pulse can also be targeted for detection. Thereby, since the presence or absence of abnormality is detected from another viewpoint, the detection accuracy can be increased.

  In the first embodiment, the first detection means 5 is constituted by software, and the second detection means 6 is constituted by hardware. However, both the detection means 5 and 6 are both software. It is also possible to configure both with hardware. Even if comprised in this way, since the presence or absence of abnormality is detected with the different generation | occurrence | production form of the said pulse, detection accuracy can be made high.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is an explanatory diagram in which the flame detection device 1 of the first embodiment is applied to the boiler 10, and FIG. 4 is a flowchart for explaining the operation of the flame detection device 1. In FIG. 3, the same components as those of the flame detection device 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the boiler 10 includes a cylindrical can body 11, a wind box 12 provided on the upper portion of the can body 11, a blower 13 that sends combustion air into the wind box 12, and the like. It is composed of

  A burner 14 directed into the can 11 and a fuel nozzle 15 are provided on the substantially central axis of the burner 14 in the wind box 12. A fuel adjustment valve 17 is provided on the fuel supply line to the fuel nozzle 15. An ultraviolet photoelectric tube 16, which is a component of the flame detection sensor 2, is inserted in the upper part of the wind box 12 and connected to the flame detection device 1.

  The determination unit 7 is electrically connected to the fuel adjustment valve 17 while a relay drive current flows to the fuel valve cutoff relay therein, but a relay current is supplied to the fuel valve cutoff relay. When it stops flowing, it is configured not to be electrically connected to the fuel adjustment valve 17. While the fuel adjustment valve 17 is electrically connected to the determination unit 7 (on state), the fuel is supplied to the fuel nozzle 15, but is electrically connected to the determination unit 7. While it is not performed (in the off state), the fuel is not supplied to the fuel nozzle 15.

  In the above configuration, the operation will be described based on the flow shown in FIG. First, when no flame is generated from the burner 14, the flame detection sensor 2 does not detect a flame, and therefore no pulse is sent to the detection means 5 and 6. Next, when a normal operation for ignition is performed, the flame detection sensor 2 detects a flame via the ultraviolet photoelectric tube 16. Thereby, the signal with flame is pulsed by the pulse converter 3 (step S1).

In step S2, the pulses are sent to the detection means 5 and 6, respectively, and the presence or absence of an abnormality is detected based on the number and width of the pulses. Both detection means 5,
If it is determined that at least one of 6 is abnormal, the process proceeds to step S3, and the supply of relay current to the fuel valve cutoff relay is stopped. As a result, the fuel adjustment valve 17 is turned off, and the supply of fuel to the fuel nozzle 15 is stopped. And it transfers to step S4 and issues a warning.

  On the other hand, if it is determined that both the detection means 5 and 6 are normal, the fuel adjustment valve 17 is in an ON state, fuel is supplied to the fuel nozzle 15, the process proceeds to step S5, and the detection of the abnormality is completed. If so, the process ends. If not, the process proceeds to step S2 to repeat the above steps.

  According to the second embodiment, in addition to the effects of the first embodiment, on / off of the fuel adjustment valve 17 is controlled by the output from the flame detection device 1, so that fail-safe combustion safety is achieved. It can be a device.

Explanatory drawing which shows the flame detection apparatus of a 1st Example. Explanatory drawing which shows the abnormality determination by the flame detection apparatus of 1st Example. Explanatory drawing which applied the flame detection apparatus of the 1st Example to the boiler. The flowchart explaining operation | movement of the flame detection apparatus of a 1st Example.

DESCRIPTION OF SYMBOLS 1 Flame detection apparatus 2 Flame detection sensor 3 Pulse converter 5 1st detection means 6 2nd detection means 7 Determination part

Claims (5)

One flame detection sensor, a pulse converter for applying a pulse of a constant frequency to the flame detection sensor, and a plurality of detection means for detecting the presence / absence of an abnormality according to the pulse generation form output from the flame detection sensor Bei example, the plurality of detecting means includes a first detecting means for detecting the presence or absence of abnormality based on any one of the generating form of the pulse, abnormality based on any one of the generating form of the pulse Second detection means for detecting presence / absence, wherein the first detection means detects the presence / absence of an abnormality by measuring the number of pulses per predetermined time from the flame detection sensor, and the second detection means A flame detection device that detects the presence or absence of an abnormality based on the width of the pulse .   One flame detection sensor, a pulse converter for applying a pulse of a constant frequency to the flame detection sensor and converting the output signal of the flame detection sensor into a pulse, and a fixed time of a pulse output from the flame detection sensor A flame detection apparatus comprising: a plurality of detection means for detecting presence / absence of abnormality by detecting two or more kinds of different generation forms among generation forms such as number, width, amplitude, and the like.   When there is no flame, no current flows, but when there is a flame, one flame detection sensor composed of an ultraviolet phototube, and a pulse of constant frequency is applied to the flame detection sensor to apply the current. Two or more of the pulse conversion device that converts the output signal of the flame detection sensor into a pulse, and the generation form of the number of pulses output from the flame detection sensor within a certain time, width, amplitude, etc. A flame detection apparatus comprising: a plurality of detection means for detecting the presence or absence of abnormality by detecting different types of generation. The plurality of detection means measure the number of the pulses per predetermined time from the flame detection sensor, detect the presence or absence of abnormality, and detect the presence or absence of abnormality based on the width of the pulse The flame detection apparatus according to claim 2, further comprising a second detection unit. A determination unit that receives a signal from the first detection unit and the second detection unit and determines that the flame detection device has an abnormality when at least one of the detection units detects the abnormality; The flame detection apparatus according to claim 4 , wherein

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