JP2020166455A - Fire detector - Google Patents

Abstract

To provide a fire detector capable of monitoring fire caused by an object to be monitored that moves in an area to be monitored over time, taking into consideration price and environmental resistance.SOLUTION: A fire detector includes: an infrared array sensor (10) that detects the amount of infrared radiation in an area to be monitored as an individual value for each of a plurality of pixels; and a detection unit (20) that acquires a plurality of detection results with the infrared array sensor while an object to be monitored is moving in the area to be monitored regarding the object to te monitored that is moving in the area to be monitored with the infrared array sensor over time, and determines whether or not a high-temperature object has passed as the object to be monitored based on the detection results.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fire detection device that determines whether or not a monitored object moving in a monitored area with the passage of time has passed as a high temperature object.

Conventionally, a fire detection device that detects a high-temperature object using an output signal of an infrared sensor and determines the occurrence of a fire has been proposed (see, for example, Patent Document 1). Infrared sensors can detect hot objects that cause a fire. Therefore, an infrared sensor may be used in cases where it is difficult to detect a fire with a normal fire detector.

There are concerns about fires in waste treatment facilities, such as difficulty in extinguishing the fire when it breaks out, or environmental pollution caused by the fire. In particular, in the process in which waste is crushed and flows through a conveyor, fires often occur, and the above-mentioned problems are a concern. As a solution to such a problem, temperature monitoring using an infrared camera has been put into practical use.

Japanese Unexamined Patent Publication No. 2004-999264

However, the prior art has the following problems.
Infrared cameras that can withstand the environment of garbage disposal facilities are very expensive, and the current situation is that the installation of infrared cameras in such facilities is slow.

In addition, the characteristics of a conveyor fire include that a high-temperature object that causes a fire passes in a short time, and that the hot air flow is blocked by accumulated dust. Due to these characteristics, it is difficult to detect a conveyor fire with high accuracy by the existing sensor fire detection method.

Further, as a sensor for detecting a conveyor fire, high performance is required for environmental resistance. Therefore, in consideration of price and environmental resistance, a fire detection device capable of performing fire monitoring caused by a monitored object moving in a monitored area with the passage of time is strongly desired.

The present invention has been made to solve the above-mentioned problems, and is caused by a monitored object that moves in a monitored area with the passage of time in consideration of price and environmental resistance. The purpose is to obtain a fire detection device capable of performing fire monitoring.

The fire detection device according to the present invention has an infrared array sensor that detects the amount of infrared rays in a monitored area as individual values for each of a plurality of pixels, and a subject that moves in the monitored area by the infrared array sensor over time. Regarding the monitored object, while the monitored object is moving in the monitored area, a plurality of detection results by the infrared array sensor are acquired, and based on the detection results, whether or not a high temperature object has passed as the monitored object is determined. It is provided with a detection unit for determining.

According to the present invention, it is possible to obtain a fire detection device capable of performing fire monitoring caused by a monitored object moving in a monitored area with the passage of time in consideration of price and environmental resistance. it can.

It is a block diagram of the fire detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which showed the specific example of the infrared array sensor used for the fire detection apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the method of determining the passage of a high temperature object in the fire detection apparatus which concerns on Embodiment 1 of this invention. It is a figure which showed the relationship between the monitoring distance and the monitoring range of the infrared array sensor in Embodiment 1 of this invention. FIG. 5 is a diagram schematically showing a monitoring range when the monitoring distance is L = 100 cm with respect to the infrared array sensor according to the first embodiment of the present invention. It is a figure which showed the specific installation example of the infrared array sensor in Embodiment 1 of this invention. It is a figure which summarized the application target example of the fire detection apparatus which concerns on Embodiment 1 of this invention.

Hereinafter, preferred embodiments of the fire detection device of the present invention will be described with reference to the drawings.

Embodiment 1.
FIG. 1 is a configuration diagram of a fire detection device according to a first embodiment of the present invention. The fire detection device according to the first embodiment includes an infrared array sensor 10 and a detection unit 20. The infrared array sensor 10 is a sensor that detects the amount of infrared rays in the monitored region 11 as individual values for each of the plurality of pixels.

An example of the monitored object 1 in the first embodiment is a waste (object) that is crushed in a waste treatment facility or the like and moves on a conveyor. Therefore, with respect to the monitored object 1 moving in the monitored area 11 by the infrared array sensor 10 with the passage of time, the detection unit 20 is time-series while the monitored object 1 is moving in the monitored area 11. Acquire multiple detection results. Further, the detection unit 20 determines whether or not the high temperature object has passed through the monitored target area 11 as the monitored object 1 based on the plurality of detection results.

FIG. 2 is a diagram showing a specific example of the infrared array sensor 10 used in the fire detection device according to the first embodiment of the present invention. The infrared array sensor 10 shown in FIG. 2A is configured by arranging infrared elements corresponding to one pixel as 8 × 8. Further, the infrared array sensor 10 shown in FIG. 2B is configured by arranging infrared elements corresponding to one pixel as 16 × 4.

The infrared array sensor 10 is available at a relatively low cost. Therefore, the fire detection device according to the first embodiment uses the infrared array sensor 10 to detect a fire caused by a monitored object moving in the monitored area 11 with the passage of time. It is a feature.

By measuring the temperature distribution in a non-contact manner using the radiation temperature measurement by the infrared array sensor 10, it is possible to detect a high temperature object even if the hot air flow or smoke cannot be detected. Further, by using the array sensor, it is possible to deal with local heat generation and a moving heat source.

In the following, a case where the monitored object 1 on the conveyor 2 passes through the monitored area 11 by the infrared array sensor 10 as the conveyor 2 moves will be described as a specific example.

FIG. 3 is a diagram for explaining a method for determining the passage of a high temperature object in the fire detection device according to the first embodiment of the present invention. In the description after FIG. 3, it is assumed that the infrared array sensor 10 is composed of an array sensor having 8 × 8 pixels as shown in FIG. 2 (a).

In FIG. 3, the state in which the monitored object 1 sequentially flows on the conveyor 2 is described in the order of (a), (b), (c), and (d) in chronological order. Specifically, FIGS. 3A to 3D show states in which the monitored object 1 passing through the monitored area 11 composed of 8 × 8 pixels is at the following positions, respectively. There is.
FIG. 3A: A state before the monitored object 1 enters the monitored area 11.
FIG. 3B: A state in which about half of the monitored object 1 has entered the monitored area 11.
FIG. 3C: A state in which the entire monitored object 1 passes through the center of the monitored area 11.
FIG. 3 (d): A state in which about half of the monitored object 1 remains in the monitored area 11.

Further, the upper part of each of FIGS. 3A to 3D schematically describes the positional relationship between the 8 × 8 pixel area, which is the monitoring target area 11 by the infrared array sensor 10, and the monitored object 1. It is shown in. On the other hand, the lower part of each of FIGS. 3A to 3D is the detection result by the infrared array sensor 10, and the pixels detected at a temperature exceeding 100 degrees are shown together with the detection temperature.

The detection unit 20 determines whether or not the monitored object 1 passing through the monitored area 11 of the infrared array sensor 10 is a high temperature object by the following procedure.
Step 1: The detection unit 20 periodically acquires the temperatures of all 64 pixels as the detection result by the infrared array sensor 10. In the example of FIG. 3, the detection results of (a), (b), (c), and (d) are sequentially acquired.

Step 2: The detection unit 20 counts the number of pixels in which a temperature exceeding the allowable upper limit temperature is detected each time the detection result by the infrared array sensor 10 is acquired. In the example of FIG. 3, the allowable upper limit temperature is set to 100 degrees, and the pixels detected at a temperature exceeding 100 degrees are shown together with the detected temperature. Therefore, in FIGS. 3A to 3D, the detection unit 20 obtains the following count values.
Count value = 0 in FIG. 3 (a).
Count value = 5 in FIG. 3 (b).
Count value = 7 in FIG. 3 (c).
Count value = 5 in FIG. 3 (d).

Step 3: The detection unit 20 determines whether or not a high-temperature object has passed as the monitored object 1 based on the count value corresponding to each detection result. In this procedure 3, the detection unit 20 can improve the detection accuracy by combining the count value of the pixels exceeding the allowable upper limit temperature with the number of continuations.

In the example of FIG. 3, the count value is a plurality of N (an integer of N = 2 or more and 5 or less) or more (that is, when there are a plurality of N or more pixels exceeding the allowable upper limit temperature) twice or three times. By continuing (that is, multiple times), it is possible to determine whether or not a high temperature object has passed. By executing such a determination process, the detection unit 20 can suppress false alarms due to accidental noise.

For example, when the size of the heat source to be the object to be monitored 1 is known in advance in the monitoring of a machine tool, the detection accuracy is improved by setting the allowable upper limit temperature and the count value N to appropriate values. be able to. Further, when the transport speed of the conveyor 2 is slower than the reference speed, the detection unit 20 depends on a larger number of times when the monitored object 1 passes through the monitored area 11 of the infrared array sensor 10. The detection result can be acquired. Therefore, in this case, it can be expected to suppress false alarms by increasing the number of continuations.

Further, the allowable upper limit temperature can be specified not only as a simple upper limit temperature as an absolute temperature but also as an upper limit temperature as a relative temperature with respect to the measurement temperature in the steady state. When the threshold value based on the relative temperature is adopted, the influence of the ambient temperature can be reduced. The allowable upper limit temperature can be set individually for each pixel, if necessary.

Further, the infrared array sensor 10 is set to an appropriate value by setting the monitoring distance corresponding to the distance from the infrared array sensor 10 to the conveyor 2 according to the size of the object 1 to be monitored and the moving speed of the conveyor 2. The monitoring range corresponding to the monitoring target area 11 of the above can be set to a desired value.

For example, it is assumed that the specifications of the infrared array sensor 10 are as follows.
・ Sensor pixel: 8 × 8 infrared thermopile array sensor ・ Monitoring range: 40 degrees each horizontally and vertically (5 degrees per pixel)
・ Measurement temperature range: 70 to 200 degrees ・ Frame rate: 12.5Hz

FIG. 4 is a diagram showing the relationship between the monitoring distance and the monitoring range of the infrared array sensor 10 according to the first embodiment of the present invention. When the infrared array sensor 10 having the above specifications is used, the monitoring distances can be set to 30 cm, 50 cm, and 100 cm to cover the monitoring range as shown in FIG. 4, respectively.

FIG. 5 is a diagram schematically showing a monitoring range when the monitoring distance is L = 100 cm with respect to the infrared array sensor 10 according to the first embodiment of the present invention. Therefore, as described above, the monitoring range can be set to a desired value by setting the monitoring distance to an appropriate value according to the size of the object to be monitored 1 and the moving speed of the conveyor 2. ..

Further, the detection unit 20 can set each parameter used when determining whether or not a high temperature object has passed, for example, as follows.
-Allowable upper limit temperature: Absolute value 150 degrees C or more, relative value 80 degrees C or more-Number of pixels: Set to 2 pixels or more-Continued number: Set the latest detection result (predetermined number of times) to 6 times, and the allowable upper limit The number of detections exceeding the temperature is set to 2 or more out of 6 times. The number of continuations in this case does not necessarily have to be a continuous number.

FIG. 6 is a diagram showing a specific installation example of the infrared array sensor 10 according to the first embodiment of the present invention. In FIG. 6, the conveyor 2 that conveys the monitored object 1 is covered with a cover 3. The cover 3 has a detector box 12 installed in an opening provided at a position facing the conveyor 2. The infrared array sensor 10 is installed inside the detector box 12 so as to face the conveyor 2. As a result, the infrared array sensor 10 can detect the temperature of each pixel of the monitored object 1 passing through the monitored area 11.

As shown in FIG. 6, by adopting a structure that is covered with the cover 3 and uses the detector box 12, it is possible to suppress the contamination of the infrared array sensor 10 due to the installation environment. Further, the detection unit 20 can automatically detect the functional deterioration due to the window portion corresponding to the front surface portion of the infrared array sensor 10 being soiled by periodically monitoring the detection temperature by the infrared array sensor 10. ..

In the first embodiment described above, fire monitoring of the monitored object 1 on the conveyor 2 has been specifically described. However, the fire detection device according to the present invention can also be applied to fire monitoring of a monitored object 1 moving in the monitored area 11 with the passage of time, such as monitoring a machine tool processing portion.

FIG. 7 is a diagram summarizing application target examples of the fire detection device according to the first embodiment of the present invention. As illustrated in FIG. 7, the targets to which the fire monitoring of the monitored object 1 moving in the monitored area 11 with the passage of time can be applied are a “garbage transfer conveyor”, a “coal conveyor”, and an “automatic”. "Machine tools" can be mentioned.

When the target is a "garbage conveyor", the heat generation source may be garbage that has become hot due to crushing, and the ignitable material may be combustible material existing around the heat generation source. In this case, by adopting the configuration as illustrated in FIG. 6, the detection unit 20 is based on the detection result of the infrared array sensor 10 in which the monitored object 1 as a transported object is installed in the detector box 12. Can be monitored for fire.

When the target is a "coal conveyor", a conveyor roller can be considered as a heat generating source, and coal powder can be considered as an igniter. In this case, the detection unit 20 can monitor the fire based on the detection result of the roller portion by the infrared array sensor 10.

Further, when the target is an "automatic machine tool", a rotating part or a cutting part can be considered as a heat generating source, and chips accumulated as an ignitable material can be considered. In this case, the detection unit 20 can locally monitor the processed portion of the parts to be sequentially processed by the infrared array sensor 10 and monitor the fire.

As described above, according to the fire detection device according to the first embodiment, the following effects can be obtained.
(Effect 1) By measuring the radiation temperature with an infrared array sensor, it is possible to detect a temperature rise before ignition and realize a relatively inexpensive device configuration.
(Effect 2) Set each parameter used to judge whether or not a high-temperature object has passed according to the situation at the site, the size of the object to be monitored, the moving speed of the object to be monitored, etc. to appropriate values. it can. As a result, it is possible to warn that a high-temperature object has passed, while preventing false alarms.

(Effect 3) By adopting an infrared array sensor having high-speed response, it becomes possible to detect a temperature rise before ignition by following the speed of a moving high-temperature object.
(Effect 4) By adopting an infrared array sensor having excellent vibration resistance and environmental resistance, it is possible to realize a device capable of detecting a temperature rise before ignition with high reliability.
(Effect 5) It is possible to automatically detect functional deterioration due to stains on the window.

1 Observed object, 2 Conveyor, 10 Infrared array sensor, 20 Detector.

Claims (4)

An infrared array sensor that detects the amount of infrared rays in the monitored area as individual values for each of multiple pixels,
With respect to the monitored object moving in the monitored area by the infrared array sensor with the passage of time, a plurality of detection results by the infrared array sensor are acquired while the monitored object is moving in the monitored area. A fire detection device including a detection unit that determines whether or not a high-temperature object has passed as the monitored object based on the detection result. The detection unit determines whether or not the high temperature object has passed based on the comparison between the detection result of each of the plurality of pixels and the allowable upper limit temperature.
The fire according to claim 1, wherein the allowable upper limit temperature can be set individually for each of the plurality of pixels and is defined as an upper limit temperature as an absolute value or an upper limit temperature as a relative value with respect to a steady state temperature. Detection device. When the detection unit determines that the pixels exceeding the permissible upper limit temperature exist a plurality of times among the most recent predetermined times of the plurality of detection results, the detection unit determines that the high temperature object has passed as the monitored object. The fire detection device according to claim 2. The infrared array sensor sets an object moving on the conveyor as the monitored object.
The detection unit is based on a comparison between the detection results of each of the plurality of pixels and the allowable upper limit temperature, and when there are a plurality of N or more pixels exceeding the allowable upper limit temperature, the high temperature object The fire detection device according to claim 2 or 3, wherein it is determined that the fire has passed.

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