Flame detection device

Abstract

This invention provides a flame detection device that can accurately determine whether or not a flame has occurred at the target of monitoring. [Solution] The flame detection device (100) comprises a temperature detection unit (10) that measures the temperature of the object being monitored and generates a temperature distribution image, and a control unit (20) that acquires the temperature distribution image from the temperature detection unit (10). Based on the acquired temperature distribution image, the control unit (20) identifies a high-temperature area, which is a part that is hotter than the surrounding area, and determines that a flame has occurred on the object being monitored if it determines that the identified high-temperature area is moving or increasing in the direction of buoyancy, which is the opposite direction to the direction of gravity, as time progresses.

Description

Technical Field

[0001] The present disclosure relates to a flame detection device for detecting the occurrence of a flame.

Background Art

[0002] In factories and other facilities, in order to detect a fire-like flame, it is routinely performed to monitor the devices and equipment in the facility using an infrared camera.

[0003] Also, as a device for detecting a flame, the following is disclosed (see, for example, Patent Document 1). The flame detection device in Patent Document 1 includes a light detection unit that images a monitoring target, and a noise detection unit that detects noises such as vibration, radio waves, and heat based on the installation environment. Further, the flame detection device can accurately detect a flame generated in the monitoring target by removing a noise signal superimposed on an electrical signal from the light detection unit using the noise detected by the noise detection unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a mode of detecting a flame using an infrared camera, a method is generally used in which a threshold value is set in advance, and when a high-temperature part exceeding the set threshold value exists in the image, it is determined that a flame has occurred.

[0006] On the other hand, there are also monitoring targets for which it is sufficient that they do not generate a flame even if they become high in temperature. When monitoring such a monitoring target, it may not be possible to distinguish whether a flame has actually occurred or only non-fire-related heat generation has occurred only by the determination using the set threshold value.

[0007] In the flame detection device described in Patent Document 1, after noise is removed, the presence or absence of flame is determined using a set threshold. Therefore, the same problems as described above are inherent in this device.

[0008] This disclosure is made to solve the above-mentioned problems and aims to provide a flame detection device that can accurately determine whether or not a flame has occurred in the monitored object. [Means for solving the problem]

[0009] The flame detection device according to this disclosure comprises a temperature detection unit that measures the temperature of a monitored object and generates a temperature distribution image, and a control unit that acquires the temperature distribution image from the temperature detection unit. The control unit identifies a high-temperature area, which is a part that is hotter than the surrounding area, based on the acquired temperature distribution image, and determines that a flame has occurred in the monitored object if it determines that the identified high-temperature area is moving or increasing in the direction of buoyancy, which is the opposite direction to the direction of gravity, as time progresses. [Effects of the Invention]

[0010] According to this disclosure, a flame detection device can be provided that can accurately determine whether or not a flame has occurred at the target being monitored. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing an example of the configuration of a flame detection device in Embodiment 1 of the present disclosure. [Figure 2] This diagram illustrates an example of a configuration where the target of monitoring is a cable, and also shows the state of the cable before a flame breaks out. [Figure 3] Figure 2 illustrates the situation when flames erupt from the cable shown. [Figure 4] This figure illustrates the situation when the infrared camera is installed in a different location than shown in Figure 2. [Figure 5]Figure 4 illustrates the situation when flames erupt from the cable at the camera position shown. [Figure 6] Figure 1 is a flowchart illustrating an example of the operation of the control unit. [Modes for carrying out the invention]

[0012] Hereinafter, preferred embodiments of the flame detection device of this disclosure will be described with reference to the drawings. The flame detection device according to this disclosure uses an infrared camera to measure the surface temperature of the object being monitored and generates a temperature distribution image. The flame detection device according to this disclosure is technically characterized by monitoring the movement of high-temperature areas within the temperature distribution image and determining that a flame has occurred on the object being monitored if the high-temperature areas move or increase in the direction opposite to the direction of gravity.

[0013] Furthermore, the flame detection device described herein is characterized by its ability to identify high-temperature areas not by threshold determination using a set threshold, but by comparing the temperature of the area of ​​interest with the surrounding temperature to identify areas that are hotter than the surrounding area.

[0014] Embodiment 1. Figure 1 is a block diagram showing an example configuration of a flame detection device in Embodiment 1 of the present disclosure.

[0015] In Figure 1, the flame detection device 100 includes an infrared camera 10, a control unit 20, an acceleration sensor 30, and a notification unit 40.

[0016] The infrared camera 10 is a temperature detection unit that measures the temperature of a monitored object, such as a device or equipment, in real time by capturing images of the object. The infrared camera 10 also generates a temperature distribution image that represents temperature using differences in hue, such as red, yellow, green, and blue.

[0017] The acceleration sensor 30 is a gravity direction detection unit that detects the direction in which gravitational acceleration acts as the direction of gravity. Alternatively, an angular velocity sensor (gyro sensor) may be used as such a gravity direction detection unit.

[0018] The control unit 20 is a functional unit in which a controller for controlling the infrared camera 10, the acceleration sensor 30, and the notification unit 40 is implemented. The control unit 20 acquires the temperature distribution image captured by the infrared camera 10, and determines whether or not a flame has occurred in the monitoring target based on the temperature distribution image.

[0019] The notification unit 40 is a functional unit that notifies the outside that a flame has occurred in the monitoring target based on the alarm command from the control unit 20. The notification unit 40 is, for example, a speaker that alarms the surroundings by voice, an LED light that alarms visually by lighting, flashing, etc., and a communication interface that outputs a fire occurrence signal to a fire receiver (not shown).

[0020] <Method for Detecting Flame> Next, the details of the method for detecting a flame by the flame detection device 100 will be described.

[0021] FIG. 2 shows an example of a mode when the monitoring target is a cable, and illustrates the state before a flame occurs in the cable. Further, FIG. 3 is a diagram illustrating the state when a flame occurs from the cable shown in FIG. 2. In FIGS. 2 and 3, the temperature distribution images captured in each state are also illustrated together.

[0022] As shown in FIG. 2, the infrared camera 10 images the cable 200 that is the monitoring target and generates a temperature distribution image in real time. Further, since the cable 200 generates heat by being energized, the temperature difference between the cable 200 and its surroundings appears as a hue difference in the temperature distribution image as shown in FIG. 2.

[0023] When the cable 200 catches fire due to some failure during energization, buoyancy and an upward airflow are generated in the direction opposite to the gravitational direction by heat. Therefore, as shown in FIG. 3, the flame rises on the buoyancy and the upward airflow and grows in the "buoyancy direction" opposite to the gravitational direction.

[0024] The flame detection device 100 determines whether or not a flame has occurred based on the flame's growth process. Specifically, the flame detection device 100 determines that a flame has occurred if it determines that the high-temperature area shown in the temperature distribution image is moving or increasing in the direction of buoyancy, which is opposite to the direction of gravity.

[0025] <Distinguishing between flame generation and non-fire-related heat generation> In the example shown in Figure 3, it was explained that flames were generated in cable 200, but it is also possible that only non-fire-related heat generation occurs partially without ignition. Therefore, the question arises as to whether it is possible to distinguish between such non-fire-related heat generation and the generation of flames.

[0026] Here, the heat generated by non-fire-related heat dissipates along the horizontal axis of the cable 200, centered on the heat-generating area. In other words, in the case of non-fire-related heat generation, unlike the flame growth process described above, the high-temperature area moves or increases horizontally.

[0027] The flame detection device 100 can distinguish whether a flame has been generated or whether the heat generation is non-fire-related by determining the difference in the diffusion direction of the high-temperature area.

[0028] Furthermore, when monitoring flat objects, if only non-fire-related heat generation occurs, the heat will diffuse outward from the heat-generating area. Therefore, the direction in which the high-temperature area moves or increases will differ from the flame growth process described above.

[0029] Therefore, even when monitoring a flat object, the flame detection device 100 can distinguish whether a flame has been generated or whether the heat is non-fire-related by determining the difference in the diffusion direction of the high-temperature area.

[0030] Furthermore, while the examples in Figures 2 and 3 assume that cable 200 is routed horizontally, it is also conceivable that the cable being monitored may be routed vertically. In this case, since non-fire-related heat dissipates upwards, just like flame growth, the question becomes whether it is possible to distinguish between non-fire-related heat dissipation and the occurrence of flames.

[0031] Even if a fire breaks out in a vertically extending cable like this, in the absence of wind, the direction of flame growth will generally follow the direction of buoyancy. Therefore, when a fire occurs, the hot parts tend to spread more easily upward than downward along the cable 200, resulting in the upper part of the cable 200 being hotter than the lower part.

[0032] Therefore, the flame detection device 100 can determine whether the high-temperature portion is moving or increasing in the direction of buoyancy over time, based on the difference in the diffusion rate of the high-temperature portion in the vertical direction (i.e., the direction of gravity and the direction of buoyancy) of the cable extending vertically, or the temperature difference of the high-temperature portion in the vertical direction, and can distinguish whether a flame has been generated or whether it is non-fire-related heat generation.

[0033] <Directions of gravity and buoyancy in temperature distribution images> Figure 4 illustrates a scenario where the infrared camera 10 is installed in a different location than shown in Figure 2. Figure 5 illustrates a scenario where flames erupt from the cable 200 at the camera position shown in Figure 4.

[0034] As described above, the flame detection device 100 determines that a flame has occurred if it determines that a high-temperature area in the temperature distribution image is moving or increasing in the direction of buoyancy, which is opposite to the direction of gravity. Therefore, in order to perform the above determination process to determine whether or not it is a flame, it is necessary to first determine the direction of gravity in the temperature distribution image and process it based on this.

[0035] On the other hand, in the temperature distribution image obtained from the infrared camera 10, the direction directly below is not necessarily the direction of gravity, as shown in Figures 2 and 3. That is, as shown in Figures 4 and 5, depending on the orientation of the infrared camera 10, the direction oblique to the image may be the direction of gravity.

[0036] Therefore, the flame detection device 100 first uses the acceleration sensor 30 to detect the actual direction of gravity, and based on that direction of gravity, derives the "direction of gravity in the image," which is the direction of gravity in the temperature distribution image.

[0037] To derive the direction of gravity within this image, information about the orientation of the infrared camera 10 is also needed, in addition to the direction of gravity.

[0038] In contrast, if the acceleration sensor 30 is fixed to the infrared camera 10, the flame detection device 100 can determine the orientation of the infrared camera 10 relative to the direction of gravity from the accelerations in the X, Y, and Z directions measured by the acceleration sensor 30.

[0039] After deriving the direction of gravity within the image, the flame detection device 100 determines the "direction of buoyancy within the image," which is the opposite direction to the direction of gravity within the image. Then, if the high-temperature area in the temperature distribution image is moving or increasing in the direction of buoyancy within the image, the flame detection device 100 determines that a flame has occurred on the cable 200.

[0040] <Operation of the control unit 20> Figure 6 is a flowchart showing an example of the operation of the control unit 20 shown in Figure 1. The control unit 20 repeatedly executes the flowchart shown in Figure 6, with the flowchart representing one cycle.

[0041] In step S101, the control unit 20 obtains the direction of gravity from the acceleration sensor 30.

[0042] Then, in step S102, the control unit 20 derives the direction of gravity in the image. As described above, the control unit 20 derives the direction of gravity in the image based on the direction of gravity detected by the acceleration sensor 30 and the orientation of the infrared camera 10.

[0043] Then, in step S103, the control unit 20 derives the direction opposite to the direction of gravity in the image as the direction of buoyancy in the image.

[0044] In step S104, the control unit 20 acquires a temperature distribution image from the infrared camera 10.

[0045] Then, in step S105, the control unit 20 identifies the high-temperature area within the temperature distribution image.

[0046] In step S105, the control unit 20 can, of course, also identify high-temperature areas in the image using predetermined threshold values.

[0047] However, in Embodiment 1, instead of using such a threshold for determination, high-temperature areas in the image are identified by comparing the temperature of the area of ​​interest with the temperature of the surrounding area.

[0048] When the infrared camera 10 is installed close to the object being monitored, the monitoring area per pixel becomes smaller, allowing for more detailed temperature acquisition. On the other hand, when the infrared camera 10 is far from the object being monitored, the monitoring area per pixel becomes larger.

[0049] When the monitoring area per pixel is large, even if there are partial temperatures higher than the set threshold, these high temperatures are averaged out along with the temperatures of other pixels that make up the same pixel and are represented as a single pixel. Therefore, even if a pixel has partial temperatures higher than the set threshold, that pixel may be considered a pixel that is "higher than the surrounding pixels, but still lower than the set threshold." In this case, threshold-based detection methods will fail to detect the high temperature.

[0050] To prevent such detection omissions, the control unit 20 takes the difference between the temperature of the area of ​​interest and the temperature of the surrounding area, and if this difference is significantly higher in the high-temperature direction compared to other areas, it identifies the area of ​​interest as a high-temperature area.

[0051] Returning to the explanation of the flowchart in Figure 6, the control unit 20 determines in step S106 whether the identified high-temperature area is moving or increasing in the direction of buoyancy within the image, which is the opposite direction to the direction of gravity within the image, as time progresses. The control unit 20 can make the determination in step S106 by comparing the temperature distribution image acquired one cycle or several cycles ago with the temperature distribution image being processed in the current step.

[0052] If the control unit 20 determines that the identified high-temperature area is not moving or increasing in the buoyancy direction within the image, it determines that no flames are occurring in the monitored area and terminates the process shown in Figure 6.

[0053] On the other hand, if the control unit 20 determines that the identified high-temperature area is moving or increasing in the direction of buoyancy within the image, it determines that a flame has occurred in the monitored object and proceeds to step S107.

[0054] In step S107, the control unit 20 uses the notification unit 40 to notify an external party and terminates the process shown in Figure 6.

[0055] Furthermore, if the infrared camera 10 is fixed in a specific position and the imaging direction remains unchanged, the processing in steps S101 to S103 may be skipped after the buoyancy direction in the image has been derived. In this case, the acceleration sensor 30 also becomes unnecessary after the buoyancy direction in the image has been derived.

[0056] On the other hand, when the flame detection device 100 is mounted on a mobile body such as a drone, the attitude of the infrared camera 10 changes sequentially. In this case, the flame detection device 100 sequentially performs the processes shown in steps S101 to S103 in Figure 6.

[0057] The characteristics of this flame detection device 100 can be summarized as follows, and it will be able to achieve its intended effect.

[0058] The flame detection device 100 includes an infrared camera 10 that measures the temperature of the object being monitored and generates a temperature distribution image, and a control unit 20 that acquires the temperature distribution image from the infrared camera 10.

[0059] Furthermore, the control unit 20 determines, based on the acquired temperature distribution image, that a high-temperature area, which is a part that is hotter than the surrounding area, is moving or increasing in the direction of buoyancy, which is the opposite direction to the direction of gravity, and determines that a flame has occurred in the monitored object.

[0060] This allows the flame detection device 100 to accurately determine whether or not a flame has occurred at the monitored object.

[0061] Furthermore, the flame detection device 100 is further equipped with an acceleration sensor 30 for detecting the direction of gravity. The control unit 20 derives the in-image gravity direction, which is the direction of gravity in the temperature distribution image, based on the direction of gravity detected by the acceleration sensor 30.

[0062] The control unit 20 then determines that a flame has occurred at the monitored object if, in the temperature distribution image acquired from the infrared camera 10, the high-temperature area is moving or increasing in the direction of buoyancy within the image, which is the opposite direction to the direction of gravity within the image.

[0063] This allows for the automatic deriving of the in-image gravity direction, which is the direction of gravity in the temperature distribution image. Therefore, even if the orientation of the infrared camera 10 changes, the flame generation detection process can be carried out in accordance with this change. [Explanation of Symbols]

[0064] 10 Infrared camera (temperature detection unit), 20 Control unit, 30 Acceleration sensor (gravity direction detection unit), 40 Notification unit, 100 Flame detection device, 200 Cable (monitoring target).

Claims

1. A temperature detection unit measures the temperature of the monitored object and generates a temperature distribution image, The system comprises a control unit that acquires the temperature distribution image from the temperature detection unit, The control unit, Based on the acquired temperature distribution image, high-temperature areas, which are regions that are hotter than the surrounding areas, are identified. If it is determined that the identified high-temperature area is moving or increasing in the direction of buoyancy, which is opposite to the direction of gravity, over time, it is determined that a flame has occurred in the monitored object. Flame detection device.

2. The control unit determines, based on the difference in diffusion velocity of the high-temperature portion in the direction of gravity and the direction of buoyancy, or the temperature difference of the high-temperature portion, whether the identified high-temperature portion is moving or increasing in the direction of buoyancy over time. The flame detection device according to claim 1.

3. The system further includes a gravity direction detection unit that detects the direction of gravity, The control unit, Based on the gravity direction detected by the gravity direction detection unit, the in-image gravity direction, which is the gravity direction in the temperature distribution image, is derived. If, in the temperature distribution image acquired from the temperature detection unit, the high-temperature area moves or increases in the direction of buoyancy within the image, which is the opposite direction to the direction of gravity within the image, then it is determined that a flame has occurred in the monitored object. The flame detection device according to claim 1 or 2.

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