JPH0451773B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fire determination device that determines whether there is a fire based on the flickering frequency of flames in the event of a fire.

(Prior art) Conventionally, in the case of devices that detect light energy emitted from flames to determine fires, the flickering frequency of flames during fires is generally 1Hz to 10Hz.
Since the flickering frequency is in the Hz range, it is determined that there is a fire when a flickering frequency within a specific range is obtained.

(Problem to be solved by the invention) However, in the conventional fire judgment based only on the flickering frequency of the flame, the flickering frequency of a non-fire flame such as a gas stove where the size of the flame does not change, for example, is When a fire occurs within a specific fire judgment range, there is a risk that an incorrect fire judgment will be made.

(Means for Solving the Problems) The present invention has been made in view of these conventional problems, and aims to further improve the reliability of fire judgments based on the flickering frequency of flames, thereby enabling accurate fire judgments. The purpose of the present invention is to provide a fire detection device that enables fire detection.

In order to achieve this objective, the present invention focuses on the fact that the flame flickering frequency obtained through fire experiments causes a frequency change that decreases as the flame spreads over time from the occurrence of the fire. A fire determining means is provided which determines that a fire has occurred when the temporal change in the flickering frequency of the flame detected by the frequency detecting means shows a decreasing tendency based on the detection output of the flame detecting means.

(Function) According to the configuration of the present invention, the flickering frequency of the flame detection signal obtained from the flame detection means that converts the optical energy of the flame into an electrical signal changes as the flame spreads in the case of a fire. For example, in the range below 10 Hz, which was previously determined to be a fire, the flicker frequency now decreases over time, and by capturing this decreasing trend in flicker frequency, it is possible to accurately determine a fire.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention.

First, to explain the configuration, 1 is a flame detector,
An optical system 2 such as a condenser lens forms an image of a flame 3 caused by a fire occurring in a warning area on a light receiving surface, and an electric signal (flame detection signal) corresponding to the light energy from the flame 3 is output.

The detection output from the flame detector 1 is given to a flicker frequency detection section 4, which detects the flickering frequency component of the flame, which is, for example, 10 Hz or less. As the flicker frequency detection section 4, a frequency analyzer that detects a frequency component consisting of fluctuations in the amplitude of the flame detection signal or a frequency filter that extracts a frequency component of 10 Hz or less that is determined to be a fire is used.

The flicker frequency of the flame detected by the flicker frequency detection section 4 is given to the frequency change determination section 5.
For example, the frequency change determination unit 5 determines that there is a fire at 10Hz.
The following temporal changes in the flicker frequency are monitored, and when a temporal change in which the flicker frequency tends to decrease is determined, a determination output is generated to the fire determining section 6.

On the other hand, in this embodiment, since a fire is determined also from the level of the flame detection signal obtained from the flame detector 1, that is, the size of the flame 3, the fire level detection section 7
and a level judgment section 8 are provided in parallel, the fire level detection section 7 detects the amplitude peak level of the flame detection signal, and the level judgment section 8 detects when the amplitude peak value exceeds a predetermined threshold level. The judgment output is given to the fire judgment section 6. As the fire determining means based on the flame level, which is comprised of the flame level detecting section 7 and the level determining section 8, it is also possible to use, for example, the one already proposed in Japanese Patent Application Laid-open No. 178621/1983.

Therefore, the fire determination section 6 outputs a fire detection signal when either the frequency change determination section 5 or the level determination section 8 obtains a determination output, or when both determination outputs are obtained. become.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Figure 2 is a graph showing the temporal change in flame flickering frequency obtained in a fire experiment in which wood was burned.In the initial state, the flame flickering frequency is 6~
7 Hz, but as time passes, that is, as the flame expands, the flicker frequency shifts to a lower side, and when the flame reaches around 1 m (about 5 minutes), it reaches a stable combustion state, and the flicker frequency at that time is About 2
It will settle down to ~4Hz.

The tendency for the flicker frequency to decrease over time obtained through fire experiments is almost the same in actual fires, and in the example shown in FIG. A flickering frequency component is detected by the flickering frequency detection section 4, and a time change of this flickering frequency component is audited by the frequency change determining section 5. When the flickering frequency component shows a decreasing tendency over time, an actual fire is detected. It is judged that there is a flame, and a judgment output is generated in the fire judgment section 6.

On the other hand, for non-fire flames such as gas stoves, the size of the flame does not change over time, so the flicker frequency component from non-fire flames is 10Hz or less, which is considered a fire. Even if it does, the flickering frequency component will not tend to decrease over time, and this will not cause erroneous fire judgment.

On the other hand, in the case of an actual fire, the time from ignition to the spread of the flame is expected to be very short, as in the case of a fire in a kerosene stove, etc., and in this case,
Since the decrease in the flicker frequency is instantaneous, it may not be possible to detect the decrease in the flicker frequency component. Therefore, in the embodiment shown in FIG. 1, a means for determining a fire based on the flame level by the fire level detecting section 7 and the level determining section 8 is separately provided, and when the flame detection level exceeds a predetermined threshold level, , so that a fire judgment output can be obtained immediately.

(Effects of the Invention) As described above, according to the present invention, the light energy emitted from the flame during a fire is detected by the flame detection means, and the flickering frequency of the flame is detected based on the detection output of the flame detection means. However, since we have provided a means to determine that there is a fire when the temporal change in the detected flicker frequency shows a decreasing trend, it is possible to make accurate fire judgments by detecting the spread of flames from the decreasing trend in the flickering frequency. , the reliability of fire judgment based on flame flickering frequency can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing changes in flame flickering frequency over time. 1: Flame detector, 2: Optical system, 3: Flame, 4: Flickering frequency detection section, 5: Frequency change judgment section, 6:
Fire judgment section, 7: Flame level detection section, 8: Level judgment section.

Claims (1)

[Claims] 1 Flame detection means for converting light energy emitted from flames into electrical signals during a fire; frequency detection means for detecting the flickering frequency of the flame based on the detection output from the flame detection means; 1. A fire determination device comprising: determination means for determining a fire by detecting a decreasing tendency of flicker frequency.