JPS61187622A - Flame detection apparatus - Google Patents

Abstract

PURPOSE:To certainly detect a flame without generating erroneous operation due to noise, by discriminating a flame when the difference of the amplitude value of the plus change portion and that of the minus change portion in flickering change is within a range from a first threshold value to a second threshold value set so as to be higher than the first threshold value. CONSTITUTION:The light energy from a flame 1 is incident to a flickering change detection means 3 through an optical apparatus 2 and the detection means 3 outputs a detection signal to an AC amplifying circuit 6. The circuit 6 amplifies the flickering frequency from the flame 1 to outputs the same to an A/D converter circuit 7 which, in turn, applies A/D conversion to this equal to output the converted signal to a flame discrimination part 9 through an input/output interface 8. The flame discrimination part 9 decodes the detection signal from the detection means 3 and discriminates the flame when the ratio of the amplitude of the plus change portion and that of the minus change portion in flickering change is within a range from a first threshold value to a second threshold value set so as to be higher than the first threshold value. A signal is outputted to an alarm circuit 10 through the interface 8 to order alarm display.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flame detection device that detects a flame based on flickering changes peculiar to the flame obtained from the flame.

(Prior Art) Conventionally, the flame has a characteristic flickering frequency, that is, IHz to 10
A so-called flicker-type flame detection device has been proposed, which detects a flame based on flickering changes peculiar to a flame, focusing on flicker changes between Hz and Hz. It is equipped with a flame sensor such as a photoelectric conversion element that outputs a signal according to the intensity of the light energy emitted, and the signal from the flame sensor is passed through a narrow band filter to extract only the frequency component unique to the flame, and the amplitude value of this flame signal is extracted. and a preset reference value, and if the amplitude value of the flame signal exceeds the reference value, it is converted into a pulse, the number of converted pulses is counted, and when the counted value reaches a predetermined value, it is determined that it is a flame. Was.

(Problem to be Solved by the Invention) However, when noise with an impactful waveform such as noise caused by a person crossing in front of the flame sensor or shot noise occurs temporarily, the level of these noises may exceed the reference value. There is a problem in that when the number of pulses is exceeded, pulse conversion is performed and pulses due to noise are counted, resulting in malfunction.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems, and it reliably detects flame without malfunctioning even if temporary noise of a level exceeding the standard value occurs. In order to provide a highly reliable flame detection device that detects a flame based on a flickering change of a predetermined level or more from a flame,
A flame discriminator is provided that determines a flame when the ratio of the amplitude value of a positive change to the amplitude value of a negative change among flicker changes takes a value within a predetermined range centered around 1, and the determination result of the flame discriminator is The flame is detected based on the

(Example) FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

First, to explain the configuration, 1 is a flame, 2 is an optical device, and 3 is a flicker change detection means for detecting flicker changes from the flame.The light energy from the flame 1 is transmitted through the optical device 2 to the flicker change detection means 3. incident on . The flicker change detection means 3 includes a photoelectric conversion circuit 4 that converts an optical signal into an electrical signal;
It is composed of a narrow band filter 5 that removes high frequency components other than the flickering frequency peculiar to flames, for example, 1 to 10 Hz, and outputs a detection signal to an AC amplifier circuit 6. The AC amplifier circuit 6 amplifies the detection signal from the flame 1 with flickering frequencies 1 to 10H2 and outputs it to the A/D conversion circuit 7. The A/D conversion circuit 7 A/D converts the signal from the AC amplifier circuit 6 and outputs the signal to the flame discrimination section 9 via the input/output interface 8. The flame discrimination unit 9 is equipped with a microcomputer inside, and when it decodes the detection signal from the flicker change detection means 3 and determines that it is a flame, it outputs a signal to the alarm circuit 10 via the input/output interface 8 and displays an alarm. command.

Next, the internal configuration of the flame discrimination section 9 will be explained. Reference numeral 11 denotes an arithmetic processing section, which outputs a detection signal from the flicker change detection means 3 obtained via the input/output interface 8 to the storage section 12 and the comparison section 13.

The arithmetic processing unit 11 also calculates a maximum amplitude A and an output ratio B, which will be explained later. The storage unit 12 sets and registers the signal level of the fire signal from the arithmetic processing unit 11 obtained first as a memory value, and then uses the signal output from the comparison unit 13 among the detection signals from the arithmetic processing unit 11 obtained sequentially. In synchronization, the signal level of the corresponding detection signal is updated and registered as a stored value.

The registration of stored values in the storage unit 12 will be explained in detail with reference to FIG. 3. When a detection signal as shown in FIG. 3 is obtained, the detection signal P1 is changed to the stored value P I
aX and also a memory f11 of a negative change in the detection signal P2
Each setting is registered as pmin, and from then on, the comparison unit 13
Based on the signal output from p IaX or p
Update and register main individually. The comparison unit 13 compares the signal level from the arithmetic processing unit 11 with the stored value p wax or P sin set and registered in the storage unit 12 .

Specifically, the signal level for a positive change in the detection signal is compared with the stored value P laX, and the signal level for a negative change in the detection signal is compared with the stored value P sin. The amplitude value of the signal is the stored value p wa
When the value of x or pmtn is exceeded, a signal indicating update registration is outputted to the storage unit 12, and at the same time, a comparison signal is outputted to the counter circuit 14.

A predetermined count value is set in advance in the counter circuit 14, which counts the comparison signal obtained from the comparison section 13, and outputs a signal to the arithmetic processing section 11 when the count value reaches the predetermined count number. Reference numeral 15 denotes a clock circuit, which constantly sends time information to the arithmetic processing unit 11, and the arithmetic processing unit 11 receives the first signal from the flicker change detection means 3 obtained via the input/output interface 8. The passage of time from the time when the first detection signal is input is monitored, and when a count output from the counter circuit 14 is obtained within a predetermined time TO,
-Start the luck operation. To explain this calculation process specifically, the final stored values p wax and P sin updated and registered in the storage unit 12 are taken out, and the maximum amplitude A is calculated by adding their respective absolute values. That is, the calculation shown in equation (1) is performed.

A −I Pmaxl+ l Psinl =
(1) If the value of the maximum amplitude A is greater than or equal to the predetermined threshold level C1, the absolute value of the stored value P wax and the stored value P
The ratio with the absolute value of 1n is calculated to determine the value of the output ratio B. That is, the calculation of equation (2) is performed.

B −l Pa+inl/l Pmaxl ・
(2> The calculation processing unit 11 is set with a first threshold C2 and a second threshold C3 higher than the first threshold C2, and the value of the output ratio B is within a predetermined range including 1. C2<B
<03, for example, if it takes a value of 0.5<8<2, it is determined that it is a flame.If the arithmetic processing unit 11 determines that it is a flame based on the calculation result, the signal is sent to the alarm circuit 10 via the input/output interface 8. Outputs a signal to issue a warning.

Figure 2 shows the control operation of the flame discriminator 9 in Figure 1)
The chart, Figure 3, is a graph showing flicker changes from a flame.

The present invention will be described in detail with reference to FIGS. 2 and 3.

In FIG. 2, in block a, the flicker change detection means 3 which sets the count value of the counter circuit 14 to a predetermined number and also resets the memory contents of the storage section 12 to initialize the flame 1
When the detection signal P1 as shown in FIG. 3 is inputted by detecting the optical energy from the block B, the counter circuit 14 does not count up in the block b, so the process proceeds to the block d via the block C. In the comparison section 13, the arithmetic processing section 11
The signal level of the detection signal P1 obtained from the above is compared with the stored value P wax stored in the storage unit 12. Storage unit 12
Since the value of the memory value p wax is set and registered as zero, the process proceeds from block d to block e, and the detection signal P
The signal level of 1 is registered in the storage unit 12 as a storage value p lax. In block f, the counter circuit 14 is connected to the comparator 1
Count the comparison output from 3. Returning from block f to block b again, the detection signal P2 as shown in FIG.
When input, since the counter circuit 14 has not counted up to a predetermined count value, the process proceeds to block d via block C. In block d, the comparison unit 13 compares the signal level of the detection signal P2 obtained from the arithmetic processing unit 11 with the stored value Pwax (-Pi) set and registered in the storage unit 12, and the signal level of the detection signal P2 is Since it is smaller than the stored value P1, the process proceeds to block 0. In block 9, the comparison unit 13 compares the signal level of the detection signal P2 and the value of the stored value P1n stored in the storage unit 12, and zero is registered in the storage unit 12 as the stored value pn+in. The process proceeds from block 9 to block h, where the signal level of the detection signal P2 is registered in the storage section 12 as a storage value P min. In block i, the counter circuit 14 counts the comparison output from the comparator 13 and counts +1, and then again in block b.
Return to Next, when the detection signal P3 is input, since the counter circuit 14 has not counted up in block b, the process proceeds to block d via block C. In block d, the comparison unit 13 compares the signal level of the detection signal P3 with the previous storage unit 1.
2 is compared with the value of Pl registered as the stored value P■aX, and since the signal level of the detection signal P3 is greater than the stored value P1, the process proceeds to block e. In block e, the signal level of the detection signal P3 is updated and registered in the storage unit 12 as a storage value P wax. The process further advances to block f, where the counter circuit 14 counts the comparison output from the comparison section 13.

Similarly, the detection signal P4. P5. P6. ...The stored value P updated and registered in the storage unit 12 every time Pn is obtained.
Compared with the signal level of l1lax or Pln and the detection signal, if the signal level of the detection signal is equal to or higher than the stored value pmax or the signal level of the detected signal is equal to or lower than the stored value pn+in, the stored value of the storage unit 12 is At the same time, the counter circuit 14 counts +1. Here, in block b, the counter circuit 14
When the count reaches a predetermined value and counts up, the process proceeds from block b to block j. In block j, the arithmetic processing unit 11 monitors the passage of time since the first detection signal P1 was input, and determines whether the count output from the counter circuit 14 is within a set time, that is, within 10. . In block j, if the set time TO has elapsed, it is determined that it is noise, and block j returns to block a again to monitor the flame. As shown in the third factor, if the count output from the counter circuit 14 is obtained within the predetermined time 10, the process proceeds from block j to block k, and the maximum amplitude A is calculated. That is, the arithmetic processing unit 11 takes out the stored values PIIlax and Pln stored in the storage unit 12 and adds their respective absolute values. In blocking, it is determined whether the maximum amplitude A is equal to or higher than a predetermined threshold level C1, and if the maximum amplitude A is less than the threshold value C1, it is determined to be noise, and the process returns to block a to monitor the flame. In blocking, if the value of the maximum amplitude A is equal to or higher than the threshold level C1, the process further proceeds to block m, where the output ratio B is calculated. That is, in the arithmetic processing section 11, the storage section 1
The ratio between the absolute value of the final stored value p_wax and the absolute value of P_win stored in step 2 is calculated, and the process proceeds to block q and block r. Block q and block “Then,
When the value of the output ratio B is a flame, it is 0.5 to approximately equal to 1.
Focusing on the fact that the value is 2, the threshold value C2- is smaller than 1.
0, 5 and a threshold value C3-2 larger than 1 are set, and the value of the output ratio B is equal to or higher than the threshold value C2 and the value of the output ratio 8 is the threshold value C3.
It is determined whether the following is true. That is, if the value of the output ratio B is less than the threshold value C2, or if the value of the output ratio B exceeds the threshold value C3, it is determined to be noise and the process returns to block a to monitor the flame. Further, if the value of the output ratio B in block q and block r is greater than or equal to the threshold value C3 and less than or equal to the threshold value 02, it is determined that there is a flame, and the process proceeds to block S, where the alarm circuit 10 is driven to display an alarm.

FIG. 4 is an overall configuration diagram showing another embodiment of the present invention.

In the embodiment shown in FIG. 4, the flame discriminating section 9 is used only when the amplitude values of the positive change and the negative change among the flicker changes from the flicker change detection means 3 are equal to or higher than the predetermined reference value 00. On the other hand, when the amplitude value of the flickering change is lower than the reference value CO, the signal output to the flame discriminating section 9 is prohibited, thereby reducing the burden of calculation processing on the flame discriminating section 9. Features. That is, a switching means 16 is provided between the AC amplifier circuit 6 and the A/D conversion circuit 7. Furthermore, an absolute value conversion circuit 17 that converts the amplitude value of the detection signal from the AC amplifier circuit 6 into an absolute value;
and a reference value setting circuit 18 for setting a predetermined reference mco, the absolute value signal from the absolute value conversion circuit 17 and the reference mco from the reference value setting circuit 18 are compared by a comparator 19, and the signal level of the detection signal is determined. The switching means 16 is closed based on the output from the comparator 19 when the value exceeds the reference value CO.

(Effects of the Invention) As explained above, according to the present invention, in a flame detection device that detects a flame (A) based on a flickering change of a predetermined level or more from a flame, a positive change of the flickering change is detected. The ratio of the amplitude value to the amplitude value of the negative change is the first lIl
By providing a flame discrimination section that discriminates as a flame when it is equal to or greater than the value and equal to or less than the second threshold set higher than the first threshold, it is possible to eliminate impact waveforms such as noise caused by people coming and going or shot noise. Even if noise occurs temporarily, the flame can be reliably detected without malfunctioning due to the noise, and the reliability of the flame detection device can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the overall configuration of the present invention, Fig. 2 is a flow diagram showing the control operation of the control unit in Fig. 1, Fig. 3 is a graph showing flickering changes from the flame, and Fig. 4 The figure is an overall configuration diagram showing another embodiment of the present invention. 1: Flame 2: Optical device 3: Flicker change detection means 4: Photoelectric conversion circuit 5: Narrow band filter 6: AC amplifier circuit 7: A/D variable circuit input/output interface 9: Flame discrimination section 10: Alarm circuit 11 : Arithmetic processing unit 12 : Storage unit 13 : Comparison unit 14 : Counter circuit 15 : Clock circuit 16 : Switching means 17 : Absolute value conversion circuit 18 Two reference value setting circuits

Claims (1)

[Claims] In a flame detection device that detects a flame based on a flicker change of a predetermined level or more from a flame, the ratio of the amplitude value of a positive change to the amplitude value of a negative change among flicker changes is a first one. 1. A flame detection device comprising: a flame determination unit that determines a flame when the flame is equal to or higher than a threshold value and equal to or lower than a second threshold value set higher than the first threshold value.