Fire alarm devices and fire alarm methods

Abstract

This system enables early and widespread detection of fires while reducing the risk of false alarms. [Solution] The fire alarm device (1) receives light (SL) from an atmosphere irradiated with laser light (LB) using a light receiving unit (12), and outputs an alarm signal when the measured value of the CO column density corresponding to the intensity of the light (SL) exceeds a reference value indicating that it has increased from the normal CO column density in that atmosphere.

Description

Technical Field

[0001] The present invention relates to a fire warning device and a fire warning method.

Background Art

[0002] Conventionally, various devices are known as a means of preparing for a fire. As such a device, there is known an alarm that is mounted on a wall surface, has a CO sensor for detecting carbon monoxide on the back side of a substrate, and has a gap through which the atmosphere of the alarm is introduced on the back side of the substrate (see, for example, Patent Document 1).

[0003] Fires can occur not only in houses but also in various places, and in some cases, it is necessary to detect fires over a wide area. In addition, various gases are generated by the combustion of objects in a fire. As a technique for detecting the presence of such gases over a wide area, there is known a device that irradiates a space to be detected with infrared light of a specific wavelength, receives the reflected light, and detects the presence or absence of the gas to be detected in the space based on the intensity of the reflected light (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the alarm disclosed in Patent Document 1, the range in which CO can be detected is limited to the range in which the ambient gas can be introduced into the device. Therefore, in order to monitor a fire over a wide area, it is necessary to install a large number of such alarms.

[0006] Note: The number in the Japanese Patent Application Laid-Open No. in the original text seems to be incorrect. I have filled in "********" here. If you can provide the correct number, I will update the translation.Furthermore, while the technology disclosed in Patent Document 2 can monitor the presence or absence of gas over a wide area along the optical path of the irradiated light, the physical quantity measured is the column density. Therefore, it is not possible to pinpoint the CO concentration or the location of CO generation at a specific point. Consequently, when monitoring the presence or absence of CO over a wide area, there is a possibility of detecting the presence of extremely low concentrations of CO as a sufficiently high amount, and there is a high risk of false alarms when determining a fire based on the detected CO value. In addition, the direction and velocity of gas diffusion differ depending on the environment being monitored. Therefore, when fire warnings are based on the detection of gases that cause fire, setting a high threshold to suppress false alarms, for example, may prevent early detection of a fire.

[0007] One aspect of the present invention aims to achieve early and widespread detection of fires while reducing the risk of false alarms. [Means for solving the problem]

[0008] To solve the above problems, a fire alarm device according to one aspect of the present invention includes: an irradiation unit that irradiates the atmosphere of a monitored object with laser light of a wavelength absorbed by a specific gas generated when the monitored object burns; a light receiving unit that receives light from the atmosphere irradiated with the laser light; and a control unit that outputs an alarm signal when the column density of the specific gas, acquired according to the signal of the intensity of the light from the atmosphere received by the light receiving unit, exceeds a reference value indicating that the column density of the specific gas in the atmosphere has increased from the normal state.

[0009] Furthermore, in order to solve the above problems, the fire alarm method according to one aspect of the present invention is monitored The atmosphere of the object to be monitored is irradiated from an irradiation unit with laser light of a wavelength absorbed by a specific gas generated when a material burns. The light from the atmosphere irradiated with the laser light is received by a light receiving unit, and the control unit outputs a warning signal when the column density of the specific gas, acquired in accordance with the signal detected by the light receiving unit, exceeds a reference value indicating that it has increased from the normal column density of the specific gas in the atmosphere. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to achieve early and widespread detection of fires while reducing the risk of false alarms. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram schematically shows the configuration of a fire alarm system according to one embodiment of the present invention. [Figure 2] This is a block diagram showing an example of a functional configuration related to fire alarm in a control unit in one embodiment of the present invention. [Figure 3] This figure schematically shows a plan view of a first example in which a fire alarm system according to one embodiment of the present invention is applied. [Figure 4] This diagram schematically shows a front view of a first example in which a fire alarm system according to one embodiment of the present invention is applied. [Figure 5] This flowchart shows an example of the process flow in a fire alarm method according to one embodiment of the present invention. [Figure 6] This figure schematically illustrates the first example of the temporal behavior of the column density detected in one embodiment of the present invention. [Figure 7] This figure schematically illustrates a second example of the temporal behavior of the column density detected in one embodiment of the present invention. [Figure 8] This diagram schematically shows a second example in which a fire alarm system according to one embodiment of the present invention is applied, viewed from above. [Figure 9] This figure schematically shows a third example in plan view of a fire alarm system according to one embodiment of the present invention being applied. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below.

[0013] [Fire warning device] The configuration of a fire warning device according to an embodiment of the present invention is schematically shown in FIG. 1. As shown in FIG. 1, the fire warning device 1 has an irradiation unit 11, a light receiving unit 12, and a control unit 13.

[0014] [Irradiation unit] The irradiation unit 11 is a device that irradiates laser light LB having a specific wavelength. The irradiation unit 11 includes, for example, an output adjustment unit 111 and a laser diode 112.

[0015] The wavelength of the laser light LB irradiated by the irradiation unit 11 is a wavelength that is absorbed by a specific gas. Therefore, the wavelength of the laser light LB is determined according to the type of the "specific gas" to be detected.

[0016] The "specific gas" is a gas generated when the monitored object burns. The "gas generated when burning" means a gas generated prior to the combustion when the monitored object burns, and a gas generated during combustion. Examples of the former include a gas generated by the monitored object during a temperature rise, and a gas generated when the monitored object is incompletely burned. More specifically, it includes a vaporized product, a decomposed product, and a compound of the monitored object material due to heat.

[0017] The "specific gas" can be appropriately selected from the type of the monitored object material and the components generated during the process in which the monitored object reaches combustion. It is preferable from the viewpoint of improving the accuracy of the determination to output a fire warning signal from the detection of the specific gas that the "specific gas" is a gas that is not substantially generated from the monitored object under normal conditions. Examples of such "specific gases" include carbon monoxide, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methane, ethanol, and carbon dioxide.

[0018] In this embodiment, the "specific gas" is carbon monoxide gas. Also, the wavelength of the laser light LB is set to 1.6 μm because the "specific gas" is carbon monoxide gas.

[0019] A "monitored object" is an item that should be monitored for fire. As will be described later, the fire alarm device 1 can detect fires early. Therefore, it is preferable that the monitored object is an item that poses a high risk when it catches fire, from the viewpoint of obtaining a higher effect in preventing fires through early detection. Examples of such high-risk items include items that are easily ignited, items that burn quickly, and items that are difficult to extinguish when they burn.

[0020] Examples of monitored objects include lithium-ion batteries, electric vehicles that use them, and backup batteries for data centers.

[0021] The laser beam LB is directed at the atmosphere surrounding the object being monitored. The "atmosphere surrounding the object being monitored" refers to the gases present around the object. An example of the atmosphere surrounding the object being monitored is the air at a distance of 1 meter or less from the surface of the object being monitored.

[0022] When the laser beam LB directly irradiates the atmosphere of the object being monitored, the laser beam LB may be directed towards the air at a distance of 1 m or less from the surface of the object being monitored. However, even if the laser beam LB is sufficiently far from the surface of the object being monitored, if the atmosphere of the object being monitored is flowing through that area, the laser beam LB may be directed into the area through which the atmosphere is flowing. Thus, in this embodiment, the irradiation unit 11 is configured to irradiate the atmosphere of the object being monitored with laser light of a wavelength absorbed by a specific gas generated when the object is burned.

[0023] [Light receiving section] The light-receiving unit 12 is a device that receives light SL from the atmosphere irradiated with laser light LB. Examples of light SL from the atmosphere include the laser light LB that has passed through the atmosphere, its reflected light, and its diffusely reflected light. The light-receiving unit 12 is a device that generates a signal corresponding to the intensity of the received light. An example of the light-receiving unit 12 is a photodiode (PD). It is preferable for the light-receiving unit 12 to receive reflected light of the laser light LB irradiated into the atmosphere from the irradiation unit 11, from the viewpoint of detecting light SL from the atmosphere with a simple configuration.

[0024] [Control Unit] The control unit 13 has at least a fire alarm function that outputs a fire alarm signal related to a fire in the monitored object by referring to the detection signal of light received by the light receiving unit 12. A block diagram of an example of the functional configuration of the control unit 13 related to fire alarm is shown in Figure 2. As shown in Figure 2, for example, the control unit 13 includes a column density acquisition unit 131, a column density increase amount acquisition unit 132, a column density increase amount determination unit 133, and a warning signal output unit 134.

[0025] The column density acquisition unit 131 acquires the column density of the aforementioned specific gas in accordance with the signal detected by the light receiving unit 12. When the specific gas is present in the atmosphere, the laser beam LB is partially absorbed by the specific gas in its optical path and is received by the light receiving unit 12 due to diffuse reflection, etc. Therefore, the unit of the measurement value of the specific gas acquired in the fire alarm device 1 is column density (concentration × distance (e.g., ppm·m)).

[0026] The column density increase acquisition unit 132 acquires the column density increase by referring to the column density of a specific gas acquired by the column density acquisition unit 131. The "column density increase" is a quantity that represents the degree of increase in column density over time. Examples of the "column density increase" include the value of the increase in column density per unit time of a specific gas (i.e., the rate of change (slope) of column density) and the time integral value of column density. When time is "t" and the column density increase is "Rco", the former is expressed as the ratio of the change in column density (d column density) to the increase in time (dt), as shown in equation (1) below, and the latter is expressed by equation (2) below.

[0027]

number

[0028] The column density increase determination unit 133 determines whether the column density increase exceeds the reference value by referring to the column density increase acquired by the column density increase acquisition unit 132 and its reference value. The "reference value" is a value that indicates that the column density of a specific gas acquired in accordance with the signal of the intensity of light SL from the aforementioned atmosphere received by the light receiving unit 12 has increased from the normal column density of the specific gas in that atmosphere, and is a value greater than the normal column density increase of the specific gas in the aforementioned atmosphere. "Normal times" refers to times other than combustion of the monitored object and its preceding stages. The normal column density increase may be a predetermined value, a column density increase acquired by normal measurements (normal measurement value), or a calculated value obtained by computer simulation.

[0029] The "standard value" can be determined appropriately based on the type of gas, the fire risk of the monitored object, and the degree of early fire warning. For example, if a particular gas is only produced during the process leading to a fire, the standard value can be set lower. Also, even if the fire risk of the monitored object is high, the standard value can be set lower from a fire prevention perspective. Furthermore, even if a high fire alert level is set, the standard value can be set lower from a fire prevention perspective.

[0030] Furthermore, the "reference value" can be determined appropriately in addition to the above, depending on the type of column density increase.

[0031] For example, if the column density increase is the rate of change in column density, the reference value will be the increase in column density per unit time of a particular gas that is greater than the increase in column density per unit time of that particular gas under normal conditions in the aforementioned atmosphere.

[0032] The column density of a specific gas to be detected increases with its generation. Therefore, the column density of a specific gas to be detected is essentially zero or a specific positive constant value under normal conditions, begins to increase during a fire, and tends to increase significantly during a fire, and can be represented by such a curve (see Figure 6). Thus, by setting a reference value at a slope between the slope of the column density under normal conditions and the slope of the column density during a fire, it becomes possible to determine a state where a specific gas is being generated more than normal but has not yet led to a fire as a state requiring fire alert. Setting the reference value towards the normal conditions (smaller value) at the rising portion of this curve is preferable from the viewpoint of enabling earlier fire alerts. Conversely, setting the reference value towards the fire conditions (larger value) is preferable from the viewpoint of suppressing false alarms and improving the reliability of the alert signal. Therefore, setting the reference value to a value for the increase in column density per unit time of a specific gas that is greater than the increase in column density per unit time of that specific gas under normal conditions in the aforementioned atmosphere is preferable from the viewpoint of achieving earlier fire detection or from the viewpoint of suppressing false alarms of fire warning signals.

[0033] Furthermore, if the increase in column density is the time integral of the column density, the reference value will be the time integral of the column density of a particular gas that is greater than the time integral of the column density of that particular gas under normal conditions in the aforementioned atmosphere.

[0034] Even when a specific gas is continuously being generated, if air convection occurs at the irradiation site of the laser beam LB, the generated specific gas is more likely to diffuse from its source, and the column density of that specific gas may change irregularly in response to increases or decreases in its generation rate (see Figure 7). However, even if the increase or decrease in column density is irregular, if the amount of the specific gas generated in a given time increases, the column density also tends to increase. Therefore, when changes in the column density of a specific gas are influenced by other factors, it is possible to achieve fire prevention by using the integrated value of the column density corresponding to the amount of the specific gas generated in a given time that could potentially lead to a fire as a reference value, and determining whether the time integral value of the actual column density of the specific gas exceeds this reference value. Therefore, setting the reference value to a time integral value of the column density of a specific gas that is greater than the time integral value of the column density of the specific gas under normal conditions in the aforementioned atmosphere is preferable from the viewpoint of achieving early fire prevention even when the source of the specific gas is influenced by external factors.

[0035] The reference value can be set as appropriate by methods such as an experimental method based on the detected column density in the fire alarm system 1 when a specific gas is supplied in a specific amount, or by a calculation method based on the distribution prediction of a specific gas using computer simulation.

[0036] The warning signal output unit 134 outputs a warning signal indicating a fire warning in response to the determination by the column density increase determination unit 133 that the acquired column density increase exceeds the standard value. This signal is transmitted to the user, for example, by wireless communication, or notified to the surroundings as a visual or audible alarm.

[0037] Thus, the control unit 13 is configured to output a warning signal when the column density of a specific gas, acquired in response to the signal of the intensity of light SL from the aforementioned atmosphere received by the light receiving unit 12, exceeds the aforementioned reference value. [others] The fire alarm device 1 further includes a focusing lens 14 that concentrates the light SL toward the light receiving unit 12, thereby increasing the detection sensitivity of the light SL. In particular, when the light SL is light that has been diffusely reflected by a fixed structure facing the fire alarm device 1 (such as a wall indoors or a partition outdoors), the configuration in which the fire alarm device 1 further includes a focusing lens 14 is preferable from the viewpoint of sufficiently increasing the detection sensitivity of the light SL in the light receiving unit 12.

[0038] Furthermore, in addition to the fire alarm function described above, the control unit 13 also includes various functional configurations related to the process from the irradiation of the laser beam LB to the output of the alarm signal, such as a function to control the irradiation of the laser beam LB at the irradiation unit 11.

[0039] Furthermore, the control unit 13 may also include functions or reference values ​​other than those described above, in addition to the fire alarm function described above. For example, the column density increase amount and the reference value referenced by the control unit 13 may be values ​​other than the rate of change of column density and the time integral of column density. For example, the column density increase amount and the reference value may be the time integral of column density. The difference from a previous measurement may also be used. If the reference value corresponding to this column density increase is set to a value that shows a sufficiently large difference over a specific sufficiently short time interval, it becomes possible to detect a significant and rapid increase in a particular gas in the atmosphere.

[0040] Furthermore, the column density increase acquisition unit 132 may acquire multiple types of column density increase amounts, and the column density increase determination unit 133 may refer to a reference value corresponding to each of the multiple types of column density increase amounts and determine whether each of the multiple types of column density increase amounts is greater than or equal to at least one of the reference values. Alternatively, the column density increase determination unit 133 may be configured to output a signal to the warning signal output unit 134 indicating that a warning signal should be output when it is determined that two or more of the multiple types of column density increase amounts exceed the reference value.

[0041] [Installation example] The fire prevention mechanism using fire alarm device 1 will be explained in more detail. A schematic example of the application of fire alarm device 1 is shown in Figures 3 and 4.

[0042] Garage 100 houses multiple electric vehicles 110. Garage 100 is a closed space with a rectangular floor 101 and ceiling, and is partitioned on all four sides by partition walls 102. Garage 100 is a garage on a ship such as a car carrier or ferry, and the electric vehicles 110 are parked as densely as possible to maximize loading efficiency. The electric vehicles 110 are equipped with lithium-ion batteries.

[0043] The fire alarm device 1 is positioned towards one side of the garage 100. The fire alarm device 1 is positioned in one corner of the garage 100, with its back to the bulkhead at one end and facing the bulkhead 102 at the other end. When the object to be monitored is an electric vehicle 110, the fire alarm device 1 is positioned so that the laser beam passes around the electric vehicle 110, for example, above or below the body of the electric vehicle 110 or between the bodies of the vehicles. In this embodiment, the laser beam LB is irradiated from one end of the garage 100 to the other end along the bulkhead at one side of the garage 100 at a height close to the floor. The laser beam LB is diffusely reflected off the surface of the bulkhead 102 at the other end, and a portion of the diffusely reflected light SL is detected by the light receiving unit 12 via the focusing lens 14.

[0044] Thus, the fire alarm device 1 is a fixed device that is fixed at the detection location, with the irradiation unit 11 fixed in a position to irradiate the atmosphere with laser light LB, and the light receiving unit 12 fixed in a position to receive light SL from the atmosphere irradiated by the laser light LB. For this reason, by installing the fire alarm device 1 facing a wall surface where the laser light LB is diffusely reflected, such as the wall surface of the garage 100, it becomes possible to detect light SL. Furthermore, because the fire alarm device 1 has a simple configuration in which the irradiation unit 11 and the light receiving unit 12 are integrated, it is compact and therefore easy to place in a suitable location in the garage 100. Thus, the fact that the fire alarm device 1 is fixed and integrally configured is preferable from the viewpoint of simplifying the configuration of the fire alarm device 1 and increasing the flexibility of installation.

[0045] The fire alarm system 1 outputs an alarm signal via wireless communication. This alarm signal is transmitted to the monitoring control PC 130 located in another room on the ship. The monitoring control PC 130 is constantly monitored by a monitoring officer.

[0046] The longitudinal distance of the garage 100 is approximately 100m. The laser beam LB is a laser beam with a wavelength of 1.6μm and is used to detect carbon monoxide. The electric vehicle 110 is the object to be monitored, carbon monoxide gas is the aforementioned specific gas, and the air inside the garage 100 is the atmosphere of the object to be monitored.

[0047] [Fire warning method] Based on the above example, an example of a fire prevention method using fire alarm device 1 will be explained. An example of the process flow in this fire prevention method is shown in the flowchart of Figure 5.

[0048] In step S11, the control unit 13 starts irradiating with laser light LB from the irradiation unit 11. For example, the control unit 13 transmits an information signal regarding the output of the laser light LB to be irradiated to the output adjustment unit 111. The output adjustment unit 111 adjusts the wavelength of the laser light to match the gas to be detected and also performs frequency modulation according to the acquired information signal. The laser diode 112 irradiates with the desired laser light LB according to the wavelength adjustment and frequency modulation by the output adjustment unit 111.

[0049] Next, in step S12, the fire alarm device 1 begins receiving the light SL (reflected light) that has been diffusely reflected by the partition wall 102 from the laser light LB. In this way, the fire alarm device 1 begins receiving the light SL.

[0050] As described above, in the fire alarm method according to this embodiment, the atmosphere of the electric vehicle 110 is irradiated from the irradiation unit 11 with laser light LB having a wavelength of 1.6 μm, which is absorbed by the carbon monoxide gas generated when the electric vehicle 110 burns, and the light SL from the atmosphere irradiated with laser light LB is received by the light receiving unit 12.

[0051] Next, in step S13, the column density acquisition unit 131 acquires the column density (ppm·m) of the optical SL in accordance with the detection signal of the optical SL in the light receiving unit 12.

[0052] Next, in step S14, the column density increase acquisition unit 132 refers to the column density of the optical SL acquired by the column density acquisition unit 131 and acquires the column density increase amount of the optical SL, for example, the rate of change of the column density or the time integral value of the column density as described above.

[0053] Next, in step S15, the column density increase determination unit 133 refers to the column density increase amount of the optical SL obtained by the column density increase amount acquisition unit 132 and the corresponding reference value to determine whether the column density increase amount of the optical SL is greater than the reference value.

[0054] If the increase in the column density of the optical SL is greater than the reference value, in step S16, the warning signal output unit 134 outputs a warning signal.

[0055] Thus, in the fire alarm method according to this embodiment, the control unit 13 outputs an alarm signal when the column density of carbon monoxide gas acquired in response to the signal detected by the light receiving unit 12 exceeds a reference value indicating that it has increased from the normal column density of carbon monoxide gas in the aforementioned atmosphere.

[0056] The emitted warning signal is displayed on the monitoring control PC130, which is monitored by the supervisor. The supervisor confirms that the situation warrants fire vigilance and takes preventative measures to prevent the fire.

[0057] On the other hand, if the increase in the column density of optical SL is less than or equal to the reference value, the control unit 13 returns to step S11. In this way, the laser light LB is continuously irradiated into the garage 100, and the reflected light (optical SL) is also continuously received, and steps S12 to S15 are repeated by the control unit 13.

[0058] [Examples of fire warnings] Here, as shown in Figures 3 and 4, an abnormal reaction occurs in the lithium-ion battery of one of the electric vehicles 110 housed in the garage 100. Due to the heat generated by the lithium-ion battery, the resin products or oil components of the electric vehicle 110 are heated, and a portion of them It undergoes thermal decomposition, generating carbon monoxide gas. Although carbon monoxide is lighter than air, it flows due to the slight airflow generated by the heat of the lithium-ion battery, spreading low and diffusing across the floor. Once it reaches the partition wall of the garage 100, it flows along the floor and the partition wall. The carbon monoxide gas 120 that diffuses and flows within the garage 100 crosses the optical path of the laser beam LB emitted by the fire alarm device 1, and then flows along that optical path.

[0059] The fire alarm system 1 detects carbon monoxide by column density (ppm·m). Therefore, even if the amount of carbon monoxide gas generated is small, or if the concentration of carbon monoxide gas inside the garage 100 is very low, the carbon monoxide caused by the diffusion and flow of the carbon monoxide gas will be detected by the fire alarm system 1.

[0060] The first example of the temporal behavior of the column density detected in the above case is schematically shown in Figure 6, and the second example is shown in Figure 7.

[0061] As described above, when carbon monoxide generated in the garage 100 flows towards the optical path of the laser beam LB and then flows along that optical path, the opportunities for the laser beam LB to collide with carbon monoxide molecules increase. Therefore, as shown in Figure 6, the column density tends to follow a curve that clearly increases from a certain point. If the rate of change in column density at the rise of this curve (for example, CD1 / t1 in the figure) is used as the reference value, the generation of carbon monoxide in the garage 100 can be detected in the initial stages of carbon monoxide generation.

[0062] On the other hand, if the garage 100 is not a closed space, and part or all of its sides or the top is open, then air flows within the garage 100 at a certain range of wind speeds and in irregular directions. In such cases, the carbon monoxide gas generated from a particular electric vehicle 110 is affected by the flowing atmosphere within the garage 100, and the opportunity for the laser beam LB of the fire alarm device 1 to collide with carbon monoxide molecules also fluctuates. Therefore, as shown in Figure 7, the column density tends to follow a curve that increases and decreases irregularly. If the value corresponding to the time integral of the column density (shaded area in the figure) at a certain time (t3 in the figure) from when the column density exceeds the normal level (t2 in the figure) is taken as the reference value, then the generation of carbon monoxide in the garage 100 can be detected at the initial stage of generation, regardless of the flow of the atmosphere within the garage 100.

[0063] When a warning signal is detected from the fire alarm device 1, preventive measures are promptly taken to prevent the fire from spreading to other vehicles or vessels. As a result, the fire in the monitored electric vehicle 110 can be prevented, and the fire may not spread to other electric vehicles 110 or to vessels.

[0064] In this way, the fire alarm system 1 detects a specific gas (carbon monoxide) by column density. Therefore, it is possible to detect the specific gas over a wide area, such as the entire garage 100 that houses multiple electric vehicles 110, rather than just individual electric vehicles 110. Furthermore, the fire alarm system 1 can quickly detect the specific gas even at low concentrations.

[0065] Furthermore, the fire alarm system 1 determines the time-dependent increase in the column density of a specific gas (carbon monoxide) and makes a determination based on this. Therefore, the possibility of a fire occurring can be detected before a fire actually happens. Thus, the fire alarm system 1 can be effective in early fire detection and initial fire prevention.

[0066] [Other installation examples] Other preferred installation examples of the fire alarm system 1 are described below. A second example of the application of the fire alarm system 1 is schematically shown in Figure 8, and a third example is shown in Figure 9.

[0067] As shown in Figure 8, two fire alarm devices 1 may be installed in the garage 100 with the optical paths of the laser beams LB intersecting each other. One device may be installed in the longitudinal direction of the garage 100. One unit is positioned to irradiate the garage 100 with laser light LB, and the other unit is positioned to irradiate the garage 100 in the shorter direction. This arrangement of fire alarm devices 1 increases the opportunities for detecting specific gases and is preferable to the installation example shown in Figure 3 in terms of detecting specific gases earlier.

[0068] Furthermore, as shown in Figure 9, four fire alarm devices 1 may be installed in the garage 100 in positions and orientations that irradiate laser beams LB along each of the partition walls. For example, each of the four fire alarm devices 1 is located at one of the four corners of the garage 100. The first device is positioned to irradiate laser beams LB along one side of the garage 100, the second device to irradiate laser beams LB along one end of the partition wall, the third device to irradiate laser beams LB along the other side of the garage 100, and the fourth device to irradiate laser beams LB along the other end of the partition wall. Such an arrangement of fire alarm devices 1 makes it possible to detect any specific gas that reaches any partition wall of the garage 100 due to the aforementioned diffusion flow along the floor surface that is characteristic of that gas. Therefore, such an arrangement of fire alarm devices 1 is preferable to the installation example shown in Figure 3 in terms of detecting specific gases earlier and more reliably.

[0069] Although not shown in the diagram, the fire alarm device 1 may be located inside the exhaust pipe leading from the garage 100, rather than inside the garage 100. For example, the fire alarm device 1 may be positioned inside the exhaust pipe to irradiate a laser beam LB along the longitudinal direction of the exhaust pipe. Even in this configuration, it is possible to detect the generation of a specific gas inside the garage 100 at an early stage.

[0070] Furthermore, the garage 100 may be equipped with baffles that rise from the floor and extend diagonally to the partition wall when viewed from above, guiding the diffusion flow of a specific gas toward the partition wall. The presence of such baffles in the garage 100 is preferable from the viewpoint of accelerating and increasing the chance of collision between the specific gas and the laser beam LB.

[0071] Furthermore, the garage 100 may be equipped with a fan that blows air toward the partition wall. The placement of such a fan in the garage 100 is preferable from the viewpoint of accelerating and increasing the chance of collision between the specific gas and the laser beam LB, and further, from the viewpoint of stabilizing the aforementioned diffusion flow of the specific gas by the stable airflow provided by the fan.

[0072] Furthermore, a pressure gradient may be formed in the garage 100, where a specific bulkhead side has lower pressure. Such a pressure gradient is also preferable from the viewpoint of accelerating and increasing the chance of collision between a specific gas and the laser beam LB.

[0073] Furthermore, a reflector may be placed in the garage 100 at a position opposite the fire alarm device 1 to reflect the laser light LB emitted from the fire alarm device 1 back towards the fire alarm device 1. The reflector may be a member that reflects the laser light LB in line with the optical axis of the light receiving unit 12, but from the viewpoint of improving the reliability of detecting light SL, it is preferable that the reflector reflects the laser light LB as scattered light. The placement of such a reflector in the garage 100 is preferable from the viewpoint of improving the reliability of detecting light SL.

[0074] Furthermore, although the fire alarm device 1 is a fixed device that is fixed and stationary at the measurement position as described above, it may also be a device in which the irradiation unit and the light receiving unit are arranged separately. For example, the fire alarm device 1 may be a separated arrangement type device that includes an irradiation unit positioned to irradiate the aforementioned atmosphere with laser light LB, and a light receiving unit positioned to receive the light SL that has passed through the atmosphere. In this case, from the viewpoint of simplifying the alignment of the optical axes of the irradiation unit and the light receiving unit, the irradiation unit may irradiate the atmosphere with scattered light from the laser light LB. The irradiating unit and / or the light-receiving unit may include a vibration damping mechanism for adjusting the optical axis.

[0075] Furthermore, the fire alarm device 1 may be a rotating (swivel) device that changes the direction of irradiation of the laser beam LB to a specific direction, in addition to the fixed or separately positioned devices described above. In this case, the control unit may be configured to adopt, as the reference value for determining the alarm signal described above, a predetermined reference value corresponding to the amount of light received, which changes depending on the direction of irradiation of the laser beam LB, or a reference value calculated to reflect the change in the amount of light received.

[0076] The aforementioned baffles, blowers, and reflectors may be provided in the garage 100, or they may be placed separately in the garage 100. These components and devices, together with the fire alarm system 1, can constitute a fire alarm structure. Similarly, the fire alarm system 1, together with other equipment used for fire alarm (for example, a temperature sensor used to measure the temperature to identify the aforementioned electric vehicle 110 that is overheating), can constitute a fire alarm structure.

[0077] Due to its performance, the fire alarm system 1 may be placed in an explosion-proof area. Therefore, the fire alarm system 1 may be configured to be explosion-proof for such use. For example, the fire alarm system 1 may be configured to be usable while housed in an explosion-proof casing. Alternatively, the fire alarm system 1 may further have a configuration that limits the energy of the laser beam LB emitted from the fire alarm system 1 so as not to become an ignition source for the surrounding explosive atmosphere.

[0078] [Examples of implementation using software] The function of the fire alarm system 1 (hereinafter also simply referred to as "the system") is a program that causes a computer to function as the system, and can be realized by a program that causes a computer to function as each control block of the system (particularly each part included in the control unit 13).

[0079] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, each of the functions described in the above embodiment can be realized.

[0080] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0081] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0082] Furthermore, each process described in the above embodiment is an AI (Artificial Intelligence) It may be executed by the control device described above. In this case, the AI ​​may be run on the control device described above, or on other devices (e.g., an edge computer or a cloud server).

[0083] 〔summary〕 A first aspect of the present invention is an irradiation unit that irradiates the atmosphere of the object to be monitored (electric vehicle 110) with laser light (LB) of a wavelength absorbed by a specific gas generated when the object to be monitored (electric vehicle 110) burns. 11) A fire alarm device (1) comprising: a light receiving unit (12) that receives light from an atmosphere irradiated with laser light; and a control unit (13) that outputs a warning signal when the column density of a specific gas acquired in accordance with the intensity signal of the light (SL) from the atmosphere received by the light receiving unit exceeds a reference value indicating that it has increased from the normal column density of the specific gas in the atmosphere. According to the first embodiment, it is possible to achieve early and wide-area detection of fire while reducing the risk of false alarms.

[0084] A second aspect of the present invention is, in the first aspect, a value for the increase per unit time of the column density of a particular gas, where the reference value is greater than the increase per unit time of the column density of the particular gas in the atmosphere under normal conditions. The second aspect is even more effective from the viewpoint of achieving earlier fire warning or suppressing false alarms of fire warning signals.

[0085] A third aspect of the present invention is a time integral of the column density of a specific gas, wherein, in the first or second aspect, the reference value is greater than the time integral of the column density of the specific gas in the atmosphere under normal conditions. The third aspect is even more effective in achieving early fire warning even when the source of the specific gas is affected by external factors.

[0086] A fourth aspect of the present invention is that, in any of the first to third aspects, the light receiving unit receives reflected light from a laser beam irradiated into the atmosphere from an irradiating unit. The fourth aspect is even more effective in terms of detecting light from the atmosphere with a simple configuration.

[0087] A fifth aspect of the present invention is that, in any of the first to fourth aspects, the irradiation unit is fixed in a position that irradiates an atmosphere with laser light, and the light receiving unit is fixed in a position that receives light from the atmosphere irradiated with laser light. The fifth aspect is even more effective from the viewpoint of simplifying the configuration of the fire alarm device and from the viewpoint of increasing the degree of freedom in placement when installing the fire alarm device at the measurement location.

[0088] A sixth aspect of the present invention is that, in any of the first to fifth aspects, the specific gas is carbon monoxide gas. The sixth aspect is even more effective in detecting the preliminary stages of a fire in the monitored object.

[0089] A seventh aspect of the present invention is a fire alarm method in which the atmosphere of a monitored object is irradiated from an irradiating unit with laser light of a wavelength absorbed by a specific gas generated when the monitored object burns, the light from the atmosphere irradiated with laser light is received by a light receiving unit, and the control unit outputs an alarm signal when the column density of the specific gas obtained in accordance with the signal detected by the light receiving unit exceeds a reference value indicating that the column density of the specific gas in the atmosphere has increased from the normal value. According to the seventh aspect, it is possible to achieve early and wide-area detection of fire while reducing the risk of false alarms.

[0090] This invention is effective in preventing fires in monitored structures by detecting specific gases generated during a fire in a monitored structure by comparing the detected column density value, which can be rapidly and sensitively detected, with a reference value indicating that it is higher than the normal value. This invention, with its such effects, is expected to contribute to achieving goals such as Goal 9 of the United Nations' Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0091] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0092] 1 Fire warning device 11 Irradiation area 12 Light receiving part 13 Control Unit 14. Focusing lens 100 Garage 101 beds 102 Bulkhead 110 Electric vehicles (objects under surveillance) 111 Output adjustment section 112 Laser Diode 120 Carbon monoxide gas (specific gas) 130 Monitoring and Control PC 131 Column Density Acquisition Unit 132 Column density increase acquisition unit 133 Column density increase determination unit 134 Warning signal output unit LB laser light SL (light from the atmosphere)

Claims

1. An irradiation unit that irradiates the atmosphere around the object being monitored with laser light of a wavelength absorbed by a specific gas generated when the object is burning, A light receiving unit that receives light from the atmosphere irradiated with the laser light, A control unit outputs a warning signal when the column density of the specific gas, acquired in accordance with the signal of the light intensity from the atmosphere received by the light receiving unit, exceeds a reference value indicating that it has increased from the normal column density of the specific gas in the atmosphere. A fire alarm system having the following features.

2. The fire alarm device according to claim 1, wherein the reference value is a value of the increase per unit time of the column density of the specific gas in the atmosphere that is greater than the increase per unit time of the column density of the specific gas under normal conditions.

3. The fire alarm device according to claim 1, wherein the reference value is a time integral of the column density of the specific gas that is greater than the time integral of the column density of the specific gas in the atmosphere under normal conditions.

4. The fire alarm device according to claim 1, wherein the light receiving unit receives reflected light of the laser light irradiated from the irradiation unit into the atmosphere.

5. The fire alarm device according to claim 1, wherein the irradiation unit is fixed in a position to irradiate the atmosphere with the laser light, and the light receiving unit is fixed in a position to receive light from the atmosphere irradiated with the laser light.

6. The fire alarm device according to claim 1, wherein the specific gas is carbon monoxide gas.

7. The atmosphere around the object being monitored is irradiated from an irradiation unit with laser light of a wavelength absorbed by a specific gas generated when the object is burning, and the light from the atmosphere irradiated with the laser light is received by a light receiving unit. The control unit outputs a warning signal when the column density of the specific gas, acquired in response to the signal detected by the light-receiving unit, exceeds a reference value indicating an increase from the normal column density of the specific gas in the atmosphere. Fire warning method.

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