Fire detection system and fire detection method

Abstract

To solve the problem that determination of a fire is difficult in the case where a mobile object with a heat generating source such as a vehicle travels.SOLUTION: A fire detection system comprises: an optical fiber distributed temperature sensor that detects return light propagating within an optical fiber and measures a temperature; a traveling position information acquisition unit that acquires information related to a traveling position of the vehicle; and a control determination unit that determines a measurement value of the optical fiber distributed temperature sensor and the information acquired by the traveling position information acquisition unit. The optical fiber of the optical fiber distributed temperature sensor is laid in a longitudinal direction of a tunnel through which a vehicle having a heat generation portion can pass on an internal wall surface of the tunnel. The control determination unit detects an occurrence of a fire in the tunnel from the temperature distribution information detected by the optical fiber distributed temperature sensor and traveling position information from the traveling position information acquisition unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire detection system and a fire detection method for detecting fires, and particularly to a fire detection system and a fire detection method suitable for detecting fires occurring in tunnels. [Background Art]

[0002] Cases of train fires have been reported in railway tunnels, and fire incidents inside tunnels have been reported in highway tunnels. There is a demand for technology to detect fires at an early stage in tunnels through which vehicles pass. Conventionally, as tunnel fire detection systems for detecting fires in vehicle-traffic tunnels, methods of detecting the spectrum of flames, methods using optical fiber sensors, and the like are known. In the method of detecting flame spectra, the optical system for detecting flames becomes soiled by dust inside the tunnel, which poses a problem in terms of cleaning. Among sensors using optical fibers, there is a distributed optical fiber sensor that uses the optical fiber itself as a sensor by detecting light scattered inside the optical fiber from light incident on one end of the optical fiber. Distributed optical fiber sensors can continuously measure physical quantities such as temperature and vibration over long distances, and do not have the problem of soiling encountered in methods that detect flame spectra, so fire detection systems using optical fibers are effective.

[0003] Patent Document 1 discloses the following technology. Specifically, three optical fibers, an optical fiber for strain measurement, an optical fiber for temperature measurement, and an optical fiber for wall surface temperature measurement, are laid along the inner wall inside the tunnel. One side of these optical fibers is sequentially connected to form a single continuous optical fiber, which is connected to a strain measuring instrument. This strain measuring instrument generates an optical pulse, injects it into the optical fiber, receives Brillouin scattered light, performs strain measurement, and outputs the measured strain amount to an abnormality monitoring device. A technology is disclosed in which this abnormality monitoring device constantly monitors the strain amount measured by the strain measuring instrument, performs signal processing on the strain amounts, and outputs a strain detection alarm, a fire detection alarm, and a tunnel outer wall abnormality alarm. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-62212 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] A distributed-type tunnel fire detection system using fiber optic temperature sensors can detect locations where temperature increases occur over long distances, such as in tunnels. However, in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling, the system may detect the heat generated by these moving objects, making it difficult to determine whether the heat is caused by a fire. [Means for solving the problem]

[0006] A typical example of a means for solving the problems of the present invention is as follows: A fire detection system for detecting a fire in a tunnel, wherein the tunnel is passable to a vehicle having a heat-generating part, the fire detection system comprises: an optical fiber distributed temperature sensor that measures temperature by detecting the reflected light of light propagating inside an optical fiber; a driving position information acquisition unit that acquires information about the driving position of the vehicle in at least the tunnel; and a control determination unit that determines the temperature distribution information acquired by the optical fiber distributed temperature sensor and the information about the driving position of the vehicle acquired by the driving position information acquisition unit, wherein the optical fiber of the optical fiber distributed temperature sensor is laid on the inner wall surface of the tunnel along the longitudinal direction of the tunnel, and the control determination unit detects the occurrence of a fire in the tunnel from the temperature distribution information detected by the optical fiber distributed temperature sensor and the information about the driving position of the vehicle acquired by the driving position information acquisition unit.

[0007] Furthermore, in an example of the fire detection system of the present invention, the optical fibers of the optical fiber distributed temperature sensor are laid in the upper part of the tunnel.

[0008] Furthermore, in an example of the fire detection system of the present invention, the control determination unit determines the location where the high temperature or temperature change is detected in the longitudinal direction of the tunnel as a first high-temperature location when the temperature distribution information indicates a temperature of a predetermined first temperature threshold or a temperature change rate of a predetermined first temperature change rate threshold, and when the vehicle travel position, which is the position where the vehicle is traveling, can be determined from the information regarding the vehicle's travel position, the control determination unit detects the occurrence of a fire when the determined vehicle travel position is not within a predetermined distance from the first high-temperature location.

[0009] Furthermore, in an example of the fire detection system of the present invention, the control determination unit determines the location where the high temperature or temperature change is detected in the longitudinal direction of the tunnel as a second high-temperature location when the vehicle is moving at a speed of a predetermined speed or higher within a predetermined distance from the first high-temperature location, and the temperature distribution information shows a temperature of a predetermined second temperature threshold or a temperature change rate of a predetermined second temperature change rate threshold or higher. The control determination unit also determines that the location where the high temperature or temperature change is detected as a second high-temperature location is not determined to be in a location that overlaps with the vehicle's position, thereby detecting the occurrence of a fire.

[0010] Furthermore, in an example of the fire detection system of the present invention, the control determination unit determines the location where the high temperature or temperature change is detected in the longitudinal direction of the tunnel as a second high-temperature location when the vehicle is moving at a speed of a predetermined speed or higher within a predetermined distance from the first high-temperature location, and the temperature distribution information indicates a temperature of a predetermined second temperature threshold or higher, or a temperature change rate of a predetermined second temperature change rate or higher. The control determination unit also determines the location where the high temperature or temperature change is detected as a second high-temperature location when the second high-temperature location is located at a position that overlaps with the vehicle, is moving together with the vehicle, and the temperature distribution information indicates a temperature of a predetermined third temperature threshold or higher.

[0011] Furthermore, in an example of the fire detection system of the present invention, the control determination unit determines the location where the high temperature or temperature change is detected in the longitudinal direction of the tunnel as a second high-temperature location when the vehicle is moving at a speed of a predetermined speed or higher within a predetermined distance from the first high-temperature location, and the temperature distribution information indicates a temperature of a predetermined second temperature threshold or higher, or a temperature change rate of a predetermined second temperature change rate or higher. The control determination unit also determines the occurrence of a fire when the second high-temperature location is located at a position that overlaps with the vehicle, is not moving together with the vehicle, and the temperature distribution information indicates a temperature of a predetermined third temperature threshold or higher.

[0012] Furthermore, in an example of the fire detection system of the present invention, the vehicle position information acquisition unit is characterized by being composed of an optical fiber distributed vibration sensor or a distributed vibration sensor that detects the reflected light of light propagating inside the optical fiber and measures vibration.

[0013] Furthermore, in an example of the fire detection system of the present invention, the optical fiber distributed temperature sensor and the optical fiber distributed vibration sensor are characterized in that they are constructed using a common optical fiber.

[0014] Furthermore, in an example of the fire detection system of the present invention, the vehicle location information acquisition unit is characterized by acquiring information regarding the vehicle's location from the route's signaling system.

[0015] Furthermore, an example of a fire detection method according to the present invention is a fire detection method performed by a fire detection system for detecting a fire in a tunnel, wherein the tunnel is passable to vehicles having heat-generating parts, the tunnel fire detection system comprises an optical fiber distributed temperature sensor that measures temperature by detecting the reflected light of light propagating inside an optical fiber, a driving position information acquisition unit that acquires information regarding the driving position of the vehicle in at least the tunnel, and a control determination unit that determines the temperature distribution information acquired by the optical fiber distributed temperature sensor and the information regarding the driving position of the vehicle acquired by the driving position information acquisition unit, wherein the optical fiber of the optical fiber distributed temperature sensor is laid on the inner wall surface of the tunnel along the longitudinal direction of the tunnel, and the fire detection method is characterized by the steps of the optical fiber distributed temperature sensor detecting temperature distribution information, the driving position information acquisition unit acquiring information regarding the driving position of the vehicle, and the control determination unit detecting the occurrence of a fire in the tunnel from the temperature distribution information and the information regarding the driving position of the vehicle.

[0016] Furthermore, in an example of the fire detection system of the present invention, the optical fibers of the optical fiber distributed vibration sensor are laid in the lower part of the tunnel. [Effects of the Invention]

[0017] According to one aspect of the present invention, fires can be accurately detected even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling. [Brief explanation of the drawing]

[0018] [Figure 1] This figure shows an overall configuration diagram of an example of a tunnel fire detection system. [Figure 2] (a) This figure shows an example configuration of a fiber optic distributed temperature sensor, and (b) This figure shows an example configuration of a fiber optic distributed vibration sensor. [Figure 3] This figure shows an example of the first fire detection flowchart. [Figure 4] This figure shows an example of temperature distribution measurement processing. [Figure 5] It is a diagram showing an example of vibration distribution measurement processing. [Figure 6] It is a diagram showing an example of detection processing for train position, speed and the like. [Figure 7] It is a diagram showing an example of a second fire detection flowchart. [Figure 8] It is a diagram showing an example of temperature change rate measurement processing. [Figure 9] It is a diagram showing an example of detection of a fire in a tunnel. [Figure 10] It is a diagram showing a comparison between a temperature rise caused by a fire and a temperature rise caused by a vehicle heat source. [Figure 11] It is a diagram showing an overall configuration diagram of another example of a tunnel fire detection system. [Figure 12] It is a diagram showing an example of a first fire detection flowchart according to Embodiment 4. [Figure 13] It is a diagram showing an example of detection processing for train position, speed and the like according to Embodiment 4. [Figure 14] It is a diagram showing an example of travel position information acquisition processing according to Embodiment 4. DETAILED DESCRIPTION OF THE INVENTION

[0019] Specific embodiments of the present invention will be described below using examples. Hereinafter, a tunnel fire detection system will be described with reference to the drawings. Although a tunnel fire detection system for detecting a fire in a tunnel is described, the fire detection system of the present invention can be applied to various passages such as tunnels, roadways, and underpasses as long as the passage is long and is traveled by heat-generating vehicles. The tunnel 120 allows passage of a vehicle having a heat generating portion. The vehicle having a heat generating portion may be a train or an automobile. A train uses devices that generate heat, such as drive motors and brake devices. In automobiles, devices that generate heat, such as engines and brake devices, are used. In the embodiments, a train will be described as an example of a vehicle.

[0020] [Embodiment 1] Figure 1 is a diagram illustrating the overall configuration of the tunnel fire detection system 101 according to Embodiment 1. The overall configuration of the tunnel fire detection system 101 will be explained using Figure 1. The tunnel fire detection system 101 includes an optical fiber distributed temperature sensor that measures temperature by detecting the reflected light of light propagating inside the optical fiber, an optical fiber distributed vibration sensor that measures vibration by detecting the reflected light of light propagating inside the optical fiber, and a control determination unit 110 that controls these sensors. The optical fiber distributed temperature sensor 104 has an optical fiber 102 of its own. The optical fiber 102 is used for temperature sensing. The optical fiber distributed vibration sensor 108 has an optical fiber 106 of its own. The optical fiber 106 is used for vibration detection. The optical fibers 102 and 106 are preferably laid on the inner wall surface of the tunnel 120 along the longitudinal direction of the tunnel 120. The control and determination unit 110 controls the optical fiber distributed temperature sensor and the optical fiber distributed vibration sensor, and detects the occurrence of a fire in the tunnel based on the temperature distribution information detected by the optical fiber distributed temperature sensor and the vibration distribution information detected by the optical fiber distributed vibration sensor, and issues an alarm when the fire occurs. The control and determination unit 110 may have a notification unit that transmits the fire alarm to people in the tunnel and / or to monitoring personnel.

[0021] The optical fiber distributed temperature sensor and optical fiber distributed vibration sensor used in this embodiment may be conventionally known, as illustrated in Figures 2(a) and 2(b), respectively.

[0022] Figure 2(a) shows an example of a distributed temperature sensor called a DTS. A DTS (Distributed Temperature Sensing) is a device that measures the ambient temperature of an optical fiber using Raman scattering. Laser light emitted from the light source laser 202 is digitally pulse-modulated by the modulator 204 to become a probe signal, which is then sent to the optical fiber 210 via the coupler 206 and the reference coil 208 for data correction. Scattering occurs throughout the fiber, but in Example 1, it is sufficient to utilize the component of the scattered signal called Raman scattering, which is inelastic scattering scattered backward. In Raman scattered light, when the optical signal collides with the lattice in the fiber, a signal that has received energy excitation (Anti-Stokes light) and a signal that has transferred energy (Stokes light) are obtained. These two scattered lights are separated by the coupler 206, amplified, and then compared. Of the scattered light, the Stokes light passes through the coupler 206 to the Stokes receiver 212, filter 214, amplifier 216, and data acquisition unit 218 before reaching the processor 220. Of the scattered light, the Anti-Stokes light passes through the coupler 206 to the Anti-Stokes receiver 222, filter 224, amplifier 226, and data acquisition unit 228 before reaching the processor 220. Since both the Stokes light and the Anti-Stokes light follow the same path, transmission losses along the way are canceled out. Based on the energy difference between the two signals, i.e., the time the probe pulse was sent, two pieces of information can be obtained: the location where the scattering occurred and temperature information. Because the actual scattered signal is very weak, the signal-to-noise ratio (S / N) can be improved by repeating the probe pulse, enabling accurate temperature measurement. With this mechanism, temperature information at various locations within the tunnel can be obtained using an optical fiber distributed temperature sensor that utilizes optical fibers laid in the tunnel.

[0023] Figure 2(b) shows an example of a distributed optical fiber vibration sensor called DAS. DAS (Distributed Acoustic Sensing) is a device that uses an optical fiber to detect vibrations around the optical fiber. Laser light emitted from the light source laser 232 is digitally pulse-modulated by the modulator 234 to become a probe signal, which is then emitted into the optical fiber 240 via the coupler 238. Scattering occurs at various points along the fiber, but DAS utilizes a component of these scattered signals called Rayleigh scattering, which is elastic scattering. Light that is sent out as a probe signal at a certain point, scattered, and returns to the coupler 238 is called light A, and the signal that returns from the next probe signal is called light B. Lights A and B reach the processor 248 via the coupler 238, balance receiver 244, and data acquisition unit 246. If the point where Rayleigh scattering occurs does not move, light A and light B are the same. However, if the point where Rayleigh scattering occurs moves, a subtle difference arises between light A and light B. This difference can be expressed as a time difference or optical path difference. Although this difference is very small, it can be displayed as a phase difference because the optical signal is a short-wavelength signal. This allows us to collect and arrange the changes in the scattering location for each probe pulse, thereby understanding the temporal movement of the scattering location. In this way, the movement along the fiber can be understood as a time series based on the fluctuations in the Rayleigh scattering location. That is, based on the time the probe pulse was sent, the location where scattering occurred and the magnitude of the vibration (the frequency component by performing a Fourier transform on the magnitude of the vibration over time) can be determined. Using this mechanism, vibration information at a specific location within the tunnel can be obtained using an optical fiber distributed vibration sensor that utilizes optical fibers laid inside the tunnel.

[0024] Next, the mechanism by which the tunnel fire detection system 101 according to the embodiment detects a fire inside a tunnel will be explained. Embodiment 1 will be explained using a tunnel 120 on which a train runs as an example. The train will be described as having equipment that generates heat, such as drive motors and braking systems.

[0025] Figures 3 to 8 are example flowcharts of the tunnel fire detection system 101 according to Embodiment 1. Figure 9 illustrates the relationship between the vehicle position and fire location within the tunnel and the measured values ​​of the optical fiber distributed temperature sensor and the optical fiber distributed vibration sensor. Furthermore, Figure 10 illustrates the temperature change measured by the optical fiber distributed temperature sensor before and after the time the fire occurred. The fire detection operation in Embodiment 1 will be explained using these figures.

[0026] In describing the tunnel fire detection system 101, the optical fiber distributed temperature sensor 104 and the optical fiber distributed vibration sensor 108 will be simply referred to as temperature sensor 104 and vibration sensor 108, respectively. When the tunnel fire detection system 101 is activated, the control determination unit 110 may send a measurement start command to the temperature sensor 104 and the vibration sensor 108. Upon receiving this measurement start command, both sensors may begin measuring according to the flow shown in Figures 4 and 5.

[0027] When the temperature sensor 104 receives the aforementioned measurement start command, it may measure the temperature distribution Tmp(p),t according to the temperature distribution measurement process 400 shown in Figure 4, as shown in step S402, and store the measurement result in a memory unit within the temperature sensor 104. In this recorded temperature distribution Tmp(p),t, t may be the time when the measurement of the temperature distribution was started, and Tmp(p),t is information including the temperature distribution at position p at time t. Here, p is the position of the temperature sensor 104 in the optical fiber, and if the optical fiber is installed along the inner wall in the longitudinal direction of the tunnel 120, it indicates the position inside the tunnel 120. Once the temperature distribution Tmp(p),t is stored, the temperature sensor 104 may send a measurement end signal to the control determination unit 110. As mentioned above, the scattered signal obtained from the probe pulse emitted from the temperature sensor 104 is very weak, so after receiving the measurement start command, the probe pulse may be repeated to obtain a temperature distribution Tmp(p),t with an improved signal-to-noise ratio (S / N). This iteration can be treated as a single measurement of the temperature distribution Tmp(p),t.

[0028] When the vibration sensor 108 receives the aforementioned measurement start command, it may measure the vibration distribution Vbrtn(p),t in step S502 according to the vibration distribution measurement process 500 shown in Figure 5, and store the measurement result in a memory unit within the vibration sensor 108. In this recorded vibration distribution Vbrtn(p),t, t is the time when the measurement of the vibration distribution was started, and Vbrtn(p),t is information including the vibration distribution at position p at time t. Here, p is the position of the vibration sensor 108 in the optical fiber, and if the optical fiber is installed along the inner wall in the longitudinal direction of the tunnel 120, it indicates the position inside the tunnel 120. Once the vibration distribution Vbrtn(p),t is stored, the vibration sensor 108 may send a measurement end signal to the control determination unit 110. Alternatively, after receiving the measurement start command, the vibration distribution Vbrtn(p),t with an improved signal-to-noise ratio (S / N) may be obtained by repeating probe pulses. As with the case of temperature sensors, this repeated process can be treated as a single measurement of the vibration distribution Vbrtn(p),t.

[0029] The control determination unit 110 sends a measurement command to both sensors again when it receives measurement completion signals from both the temperature sensor 104 and the vibration sensor 108. With this configuration, both sensors perform measurements at the same time, and information for the same time period can be obtained for the temperature distribution information obtained from the temperature sensor 104 and the vibration information obtained from the vibration sensor 108. In addition, the temperature sensor 104 and the vibration sensor 108 record the temperature distribution Tmp(p),t and vibration distribution Vbrtn(p),t at their respective time t for each measurement. This recording method may be updated each time; that is, the latest information may always be recorded. This configuration saves memory for recording this information. Alternatively, the measurement results of both sensors for a predetermined number of times may be recorded. This predetermined number can be arbitrarily determined. With this configuration, information for past time periods can be recorded along with the latest information for the temperature distribution Tmp(p),t and vibration distribution Vbrtn(p),t. Furthermore, it is convenient for observing changes between the latest information and past information. It also has the effect of making calculations easier between the latest information and past information.

[0030] Next, the fire detection process will be described. Figure 3 is an example flowchart for the fire detection process. When the tunnel fire detection system 101 is activated, the control and determination unit 110 activates the first fire detection flowchart example 300 shown in Figure 3. The fire detection process flowchart may be activated at a timing when the necessary temperature distribution Tmp(p),t and vibration distribution Vbrtn(p),t are obtained.

[0031] The control determination unit 110 may consist of a microcontroller having a calculation unit, a storage unit accessible by the calculation unit, an interface unit, and memory. When the fire detection flowchart example 300 is started in the control determination unit 110, step S302 "Read temperature distribution Tmp(p),t" is executed. The temperature distribution Tmp(p),t read here may be the latest information measured and stored in the temperature distribution measurement process 400. Next, step S304 "Read vibration distribution Vbrtn(p),t" is executed. The vibration distribution Vbrtn(p),t read here may be information measured and stored in the vibration distribution measurement process 500, and may be at the time corresponding to the temperature distribution Tmp(p),t read in step S302. However, it is preferable that the Vbrtn(p),t read in step S304 be the latest information measured and stored in the vibration distribution measurement process 500. Since the temperature distribution measurement process 400 and the vibration distribution measurement process 500 are performed in a sufficiently short time compared to the time it takes for a fire to spread, the latest temperature distribution Tmp(p),t and the latest vibration distribution Vbrtn(p),t can be treated as being from substantially the same time.

[0032] Following step S304, step S306 executes the "train position, speed, etc. detection" process. Figure 6 shows the specific processing in step S306 "train position, speed, etc. detection". In the train position, speed, etc. detection 600 shown in Figure 6, first in step S602 it is determined whether or not a train is in the tunnel. In this determination, the latest vibration distribution Vbrtn(p),t saved in the vibration distribution measurement process 500 may be read first. Next, it may be determined whether there is a location b where "Vbrtn(p),t≧ThV" for Vbrtn(p),t. The train vibration threshold ThV is a threshold that the vibration sensor 108 uses to determine the vibration when a train is running from the observed vibration distribution data. Based on this determination result, in step S604 it may be determined that a train is running at a location p where "Vbrtn(p),t≧ThV" exists. That is, if the vibration distribution information indicates a location where vibration is greater than or equal to a predetermined vibration threshold ThV and can be determined as the vehicle position, it may be determined that a train is running at that location. Here, if the range of position p is a predetermined length Ltrain, it may be determined that a train is running at that position. The range of position p that is greater than or equal to this predetermined length Ltrain, such that "Vbrtn(p), t≧ThV", may be determined as the train's location b. The train's location is the train's position, i.e., the train's running position. Let the coordinates of both ends of location b be Pv1 and Pv2, provided that "Pv2>Pv1". If at least one of the coordinates Pv1 and Pv2 is within the coordinates Pstart and Pend of both ends of the tunnel, it may be determined that a train is in the tunnel. In step S602, if a train is in the tunnel, proceed to Yes; otherwise, proceed to No. The coordinates of location b are stored in the memory of the control determination unit 110. The predetermined length Ltrain may be determined according to the train running through the tunnel 120. Even if a train is present in the tunnel, if it is traveling at a low speed, the vibration sensor 108 will not detect the train's vibrations, and it will be determined that no train is present, meaning that location b does not exist. However, in this case, no wind is generated by the train's movement that would affect fire detection, so there is no problem with fire detection.As mentioned above, the vibration sensor can be said to acquire information regarding the vehicle's position within the tunnel.

[0033] In step S602, if no train presence is detected, the process proceeds to No in step S602, and the train position and speed detection 600 process is completed. A train presence flag may be prepared, and if no train presence is detected, the flag may be set to not present. In step S602, if a train presence is detected, the process proceeds to Yes. Here, if a train presence is detected, the aforementioned train presence flag may be set to present. The train presence flag may also be used to determine whether a train is inside a tunnel. In the following step S604, the train position may be detected as coordinates Pb1 and Pb2 corresponding to location b determined in step S602.

[0034] Next, in step S606, the train speed and direction of movement may be detected. In step S606, the vibration distribution Vbrtn(p),t at time t2, which is a predetermined time after the measurement time t1 of the vibration distribution Vbrtn(p),t read in step S602, is read from the vibration sensor 108. Using this newly read vibration distribution, the same processing as described above is performed to detect the new train position. By taking the difference between this new train position and the previous train position, the direction of travel information of the train can be obtained. In addition, by dividing the difference between the new train position and the previous train position by time (t2-t1), the train speed information can be obtained. The train speed information obtained here is called Vtrain,t, and Vtrain,t may be stored in the memory of the control determination unit 110. In Vtrain,t, "t" may be the time when the vibration distribution Vbrtn(p),t from which the speed information was obtained was acquired.

[0035] Furthermore, in the train position and speed detection 600, step S608 "Detection of train stop in tunnel" detects whether the train has stopped inside the tunnel. In this detection of train stop in tunnel, it is advisable to estimate that the train has stopped from the changes in the train speed information obtained sequentially. That is, as the train speed decreases, the vibrations generated by the train decrease accordingly, so that vibrations caused by the train are no longer detected in the vibration distribution Vbrtn(p),t from a certain speed onward. In step S608, it is advisable to monitor the train's position and speed information over time, saving it as history, and to store the position at the point when the train's speed has decreased and vibrations caused by the train are no longer detected in the vibration distribution Vbrtn(p),t as the train stop position. Note that the processing in step S608 "Detection of train stop in tunnel" may not be performed within the train position and speed detection 600, but as a separate, independent process. By making it an independent process, the processing time of the train position and speed detection 600 itself can be shortened. Train stopping position information can be used to determine whether a train is in a safe or dangerous location when a fire is detected, as will be discussed later.

[0036] Following step S306, in step S308, it is determined whether there is a high-temperature location a1 where "Tmp(p),t≧Th1" for the temperature distribution Tmp(p),t read in step S302. If there is no high-temperature location a1 where "Tmp(p),t≧Th1" exists, it is determined that no fire has occurred in the tunnel, and the process proceeds to NO in step S308, and the process of step S302 is repeated. If there is a high-temperature location a1 where "Tmp(p),t≧Th1" exists, the process proceeds to Yes in step S308. Th1 is a temperature threshold, and is one of the thresholds at which the temperature sensor 104 detects a fire when one occurs. This Th1 may also be a threshold that detects a fire when there is no wind caused by the movement of a train at the fire site. In Figure 9(a), the temperature distribution 922 corresponding to train 912 is an example of this. The range between positions Pa1 and Pa2 satisfies "Tmp(p),t≧Th1". Furthermore, in Figure 9(a), the temperature distribution 926 satisfies "Tmp(p), t≧Th1" in the range between positions Pa3 and Pa4. Both of these ranges are defined as high-temperature location a1. In this specification, a width with a certain size, rather than a single point, may be expressed as "position p" for convenience. The waveform in the temperature distribution 922 is due to factors such as the uneven distribution of the train's drive motors and brake devices in some of the cars of the train.

[0037] Following the processing in step S308, the processing in step S310 will be described. In step S310, it is determined whether a train is present near the high-temperature location a1 that satisfies "Tmp(p),t≧Th1" detected in step S308. In step S310, the relationship between the high-temperature location a1 satisfying "Tmp(p),t≧Th1" detected in step S308 and the train position detected in step S306 may be determined. Hereinafter, in step S310, the distance threshold corresponding to "near" in "Is there a train near location a1?" is referred to as the proximity threshold Lnear. Lnear is a positive value. Let P1 and P2 be the positions of the two ends of the coordinates of the high-temperature location a1, with the condition that "P1 < P2". Similarly, let Pv1 and Pv2 be the train position detected in step S306. When at least one of Pv1 and Pv2 exists between "P1-Lnear" and "P2+Lnear", it is determined in step S310 that a train is present near the high-temperature location a1 satisfying "Tmp(p),t≧Th1". In step S310, if a train is present near the high-temperature location a1 satisfying "Tmp(p),t≧Th1", the process proceeds to Yes; if no train is present, the process proceeds to No. Here, the proximity threshold Lnear is a reference distance at which the wind generated in the tunnel by the running train no longer affects the detection of fire-induced temperature by the temperature sensor 104 at the location where the fire broke out. Since the influence of the wind generated by the train fluctuates, the proximity threshold Lnear does not have mathematical strictness in the "proximity" determination. If the determination in step S310 is No, after executing the processing of "tunnel fire alarm issuing" in step S332, the process returns to the processing of step S302. If the determination in step S310 is Yes, the process proceeds to the processing of step S312. In the example of FIG. 9(a), although the temperature distribution 922 is the temperature distribution generated by the train 912, the determination in step S310 is Yes. However, in this case, subsequent processing is performed to prevent it from being determined as a fire. In the example of FIG. 9(a), regarding the temperature distribution 926, if the train 912 is "near" the high-temperature location a1 defined by coordinates (Pa3, Pa4), it is determined as Yes; if it is not "near", it is determined as No.

[0038] If the determination in step S310 is No, then in step S308, there is a high-temperature location a1 where "Tmp(p), t≧Th1", and in step S310, there is no train near high-temperature location a1, so it is determined that a fire has occurred at high-temperature location a1. S332 The "tunnel fire alarm" process is executed at step S310. If the determination in step S310 is No, a tunnel fire alarm is triggered when the control determination unit 110 determines that the detection location in the longitudinal direction of the tunnel 120 is a high-temperature location a1 when the temperature distribution information output from the temperature sensor 104 indicates a temperature of or greater than a predetermined first temperature threshold Th1, and does not determine that there is a location within the threshold Lnear near the high-temperature location a1 where the vibration distribution information output from the optical fiber distributed vibration sensor 108 is greater than or equal to the train vibration threshold ThV.

[0039] The tunnel fire alarm process in step S332 notifies that a fire has occurred inside the tunnel. This notification may be made by an audible signal such as voice, or by displaying predetermined characters or graphics on a display unit. If notified by an audible signal, the fire can be notified by voice to the control room that controls train operations. If notified on a display unit, the fire can be displayed on the control console that also controls train operations. Furthermore, this notification may be sent to a system that manages train operations and used for control to stop the train in a safe location.

[0040] After determining Yes in step S310, step S312 determines whether "train speed ≥ speed threshold". The speed threshold is affected by the wind caused by the train when the temperature sensor 104 detects a temperature caused by a fire. This wind depends on the distance between the fire location and the location where the train is traveling, as well as the speed of the train. The speed threshold Tspeed is the speed threshold that affects the temperature sensor 104 when it detects a temperature caused by a fire, when the train is traveling within the vicinity threshold Lnear. If the determination in step S312 is Yes, the process proceeds to step S314. If the determination in step S312 is No, the process in step S332 "tunnel fire alarm" is executed, and then the process returns to step S302.

[0041] In step S314, it is determined whether there is a location a2 where Tmp(p),t ≥ temperature threshold Th2.

[0042] Here, we will summarize the thresholds for detecting temperature conditions. The first temperature threshold Th1 is the temperature threshold for detecting a fire when there is no train near the fire location, i.e., when there is no wind caused by train movement. The second temperature threshold Th2 is the temperature threshold for detecting a fire when there is wind caused by train movement, and "Th1 > Th2" applies. The third temperature threshold Th3 is the temperature threshold for detecting a fire when there is wind due to the movement of a train near the fire location, or when a moving train is on fire, and "Th3 > Th1" applies. It is preferable to set Th1 and Th3 so that the temperature due to the heat exhausted by the train is higher than Th1 and lower than Th3. The aforementioned temperature due to the heat exhausted by the train is the temperature generated by heat-generating equipment such as drive motors and brake systems when the train is running, and the heat exhausted by the air conditioning system. This temperature is the temperature at the location detected by the optical fiber of the temperature sensor 104.

[0043] Next, we will explain the relationship between the train's waste heat and the temperature detected by the temperature sensor 104. Figure 9 shows the relationship between the train's waste heat and the temperature detected by the temperature sensor 104. Figure 9 illustrates the vehicle position, vibration sensor measurement value, and temperature sensor measurement value at three different times T1, T2, and T3, respectively. Figures 9(a), (b), and (c) correspond to times T1, T2, and T3, respectively. As illustrated in Figure 9(a), the temperature sensor 104 detects the temperature due to the train's waste heat at the position of train 912 and outputs the temperature distribution as a measurement value. In the graphs of the temperature sensor measurement value and vibration sensor measurement value in Figure 9, Pstart and Pend indicate the positions at the ends of the tunnel 120, respectively.

[0044] Let's continue explaining the process in step S314. Step S314 is a pre-processing step for detecting a fire under conditions where there is wind due to the movement of a train. We will explain the "location a1 where Tmp(p),t ≥ temperature threshold Th2" using the example shown in Figure 9. In Figure 9(a), train 912 is running in the tunnel and a fire 914 has occurred. Corresponding to the position inside the tunnel, the temperature sensor measurement values ​​show a temperature distribution 922 corresponding to the position of train 912, and temperature distributions 924, 924, and 928 corresponding to the fire 914. Temperature distributions 924, 926, and 928 change depending on the state of the fire 914, and the observed value in a single measurement is one of these. Here, if temperature distribution 924 is observed corresponding to the fire 914, there are two "location a2 where Tmp(p),t ≥ temperature threshold Th2": coordinates (Pa1, Pa2) corresponding to temperature distribution 922 and coordinates (Pa3, Pa4) corresponding to temperature distribution 924. These coordinates Pa1, Pa2, Pa3, and Pa4 represent the coordinates of the intersection points between the temperature distribution and the thresholds Th1, Th2, and Th3. More precisely, the coordinate values ​​differ depending on the threshold, but for the sake of plotting, all thresholds are represented by the same coordinates. This representation is the same in Figure 9.

[0045] If the result in step S314 is Yes, proceed to step S316; if the result in step S314 is No, return to step S302.

[0046] In step S316, it is determined whether the high-temperature location a2 obtained in step S314 coincides with the train position. The method for determining the train position is the same as the process in steps S602 and 604 of the train position and speed detection 600 in step S306.

[0047] If the result in step S316 is Yes, proceed to step S318. On the other hand, if the result in step S316 is No, proceed to step S332. If the result in step S316 is No, it is determined that a fire in the tunnel has been detected, rather than heat exhaust from a train, and a tunnel fire alarm is issued in step S332.

[0048] The determination in step S316 is No and a tunnel fire alarm is triggered in the following cases. Specifically, the control determination unit 110 determines that the detection location in the longitudinal direction of the tunnel 120 is a high-temperature location a1 when the temperature distribution information output from the temperature sensor 104 indicates a temperature of a predetermined first temperature threshold Th1 or higher. If the vibration distribution information output from the vibration sensor 108 indicates a train position where the vibration is greater than the vibration threshold ThV, and the train is moving at a speed of a predetermined speed Tspeed or higher within a nearby threshold Lnear from the high-temperature location a1, and there is a high-temperature location a2 where the temperature distribution information output from the temperature sensor 104 indicates a temperature of a predetermined second temperature threshold Th2 or higher, and the high-temperature location a2 does not coincide with the train position, then a fire alarm is triggered. In this embodiment, as shown in Figure 3, the process started from step S302 and proceeded to step S316. However, this is just one example, and in the fire detection flowchart example 300, the process may proceed to step S316 without going through steps S308 to S312. In this case, when processing step S316, it is also possible to perform the processing in step S306 within step S316 to determine the train position.

[0049] The process in step S318 will now be explained. In step S318, it is determined whether the high-temperature location a2 detected in step S314 is moving with the train. In this determination, the high-temperature location a2 and the train position may be determined from the temperature distribution Tmp(p),t data and vibration distribution Vbrtn(p),t data acquired at a certain time, and a new high-temperature location a2 and a new train position may be determined from the temperature distribution Tmp(p),t data and vibration distribution Vbrtn(p),t data at a time predetermined to have elapsed from that time, and the relationship between the coordinates of the high-temperature location a2 and the coordinates of the train position at both times may be determined. For example, it may be determined whether the difference between the smaller coordinate of the train position and the smaller coordinate of the high-temperature location a2 at both times is within a predetermined error. If this difference is within a predetermined error, it may be determined that "location a1 is moving with the train". Furthermore, in the process of step S318, the determination process of whether "train speed ≥ speed threshold" as performed in step S312 may be added. Adding this determination regarding train speed can improve the accuracy of fire detection. The predetermined time elapsed in the aforementioned "predetermined time" may be, for example, 0.1 seconds, 0.2 seconds, 0.5 seconds, or 1 second. The aforementioned "predetermined error" may be set according to the speed of the train in motion and the state of the fire that occurs. If the result in step S318 is Yes, proceed to step S320; if the result is No, proceed to step S330.

[0050] The process in step S320 will now be explained. In step S320, it may be determined whether there is a high-temperature location a3 where "temperature distribution Tmp(p), t ≥ temperature threshold Th3". Th3 may be the threshold for detecting a fire when a moving train is on fire. The process in step S320 may be the same as the process performed in step S314, but applied to the temperature threshold Th3. An example of this is when temperature distribution 964, which is part of temperature distribution 962 in Figure 9(c), is detected by the temperature threshold Th3. Temperature distribution 964 is caused by a fire 914 that occurred on train 912.

[0051] If the result in step S320 is "Yes", proceed to step S322; otherwise, return to step S302.

[0052] The train fire alarm process in step S322 notifies that a fire has occurred on the train. This notification may be made by an audible signal such as voice, or by displaying predetermined characters or graphics on a display unit. If notified by an audible signal, the control room that controls the train's operation can be notified of the fire by voice. If notified on a display unit, the fire can be displayed on the control console that also controls the train's operation. Furthermore, this notification may be sent to a system that manages the train's operation and used for control to stop the train in a safe location. After the process in step S322 is completed, the process returns to step S302.

[0053] The train fire alarm processing in step S322 is performed via step S320 in the following cases. Specifically, the control determination unit 110 determines that if there is a high-temperature location a1 where the temperature distribution information output from the temperature sensor 104 indicates a temperature of Th1 or higher, there is a train near high-temperature location a1, the train's speed is above a predetermined threshold, and the detection position is above the longitudinal temperature threshold Th2 of the tunnel 120 is high-temperature location a2. The vibration distribution information output from the vibration sensor 108 indicates a position where vibrations greater than a predetermined vibration threshold ThV are observed, and the train position is located at a position that overlaps with the train position and is moving with the train position at a predetermined speed Tspeed or higher, the temperature distribution information output from the temperature sensor 104 indicates a temperature higher than a predetermined third temperature threshold Th3, then the control determination unit 110 detects the occurrence of a fire.

[0054] Next, we will explain the process in step S330 when No is determined in step S318. The process in step S330 can be the same as the process in step S320. If Yes is determined in step S330, proceed to step S332; if No is determined, return to step S302. For example, a temperature distribution 954 that overlaps with the temperature distribution 952 in Figure 9(b) is detected at the temperature threshold Th3. The temperature distribution 954 is caused by the fire 914.

[0055] The "tunnel fire alarm" process in step S332 is as described above. In this embodiment, as shown in Figure 3, the process started from step S302 and proceeded to step S330. However, this is just one example, and in the fire detection flowchart example 300, the process may proceed to step S330 without going through steps S308 to S312. In this case, in the process of step S330, the process of step S306 can be performed in step S316 to determine the train position. Alternatively, in step S314, the same process as in step S320 can be performed, and the flow can be configured so that a fire alarm is issued if the result is Yes, and returns to step S302 if the result is No. In this case, the fire detection flowchart example 300 does not have steps S316 onwards. In this case, it is not necessary to distinguish between tunnel fires and train fires when issuing a fire alarm.

[0056] In Example 1 described so far, as shown in S308, an example was explained in which a location showing a high temperature, such as a high-temperature location a1, is detected by comparing the temperature distribution Tmp(p),t with a temperature threshold to perform fire detection. As a variation of Example 1, tunnel fires and train fires can also be detected using the rate of temperature change without using a temperature threshold. That is, as a variation of Example 1, by comparing the temperature distribution Tmp(p),t at two different time points, for example, the distribution of the rate of temperature change Tgrdnt over the entire range where the temperature is being measured can be calculated, and the distribution of this rate of temperature change Tgrdnt can be compared with temperature change thresholds Gfire1 and Gfire2 to detect a fire. This process can also be performed in step S302 to determine location a1. The same applies in step S314. Determining whether a location exceeding a certain rate of temperature change coincides with the train's position, and whether that location moves with the train, can also be done by performing the same process as performed in S316 and S318 in Figure 3 for a certain location, such as a high-temperature location a2, for locations exceeding a certain rate of temperature change. This process can also be implemented using the process described in Example 2 below. Therefore, tunnel fires and train fires can be detected using the rate of temperature change without using a temperature threshold.

[0057] According to Example 1 and its modifications, fires can be accurately detected even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling.

[0058] [Example 2] Next, a tunnel fire detection system 101 according to Embodiment 2 of the present invention will be described. The configuration and hardware configuration of the tunnel fire detection system 101 according to Embodiment 2 may be the same as those of Embodiment 1, so these will be omitted from the description. Embodiment 2 differs from Embodiment 1 in the method of detecting fire. Figure 7 shows an example flowchart of the tunnel fire detection system 101 according to Embodiment 2. Embodiment 2 will be described with reference to Figure 7.

[0059] When the tunnel fire detection system 101 is activated, the control determination unit 110 sends a measurement start command to the temperature sensor 104 and the vibration sensor 108. Upon receiving this measurement start command, both sensors 104 and 108 begin measuring according to the flow shown in Figures 4 and 5. The temperature distribution measurement process 400 and the vibration distribution measurement process 500 are the same as in Embodiment 1.

[0060] The tunnel fire detection process is performed in the control determination unit 110. When the fire detection flowchart example 700 is activated in the control determination unit 110, step S702 "Read temperature distribution Tmp(p),t" is executed. Next, step S704 "Read vibration distribution Vbrtn(p),t" is executed. Then, in step 7306, the process of "Detecting train position, speed, etc." is executed. In step S708, it is determined whether there is a location a1 where "Tmp(p),t≧Th1" for the temperature distribution Tmp(p),t read in step S302. The processes from step S702 to step S708 may be the same as the processes from step S302 to step S308 in Example 1.

[0061] The process in step S710 is the same as the process in step S310 in Example 1, but if it is determined to be No, the process proceeds to step S730.

[0062] The process in step S712 is the same as the process in step S312 in Example 1, but if it is determined to be No, the process proceeds to step S730.

[0063] In step S714, the "calculation of the temperature change rate Tgrdnt1 for a1" is performed. The temperature change rate is the rate at which the temperature at a certain location changes over a predetermined period of time.

[0064] FIG. 8 shows a temperature change rate calculation process 800, which is a specific example of processing in step S714. In the temperature change rate calculation process 800, first, in step S802, a temperature distribution Tmp(p),t1 at that point in time, for example, at time t1, is read. Next, in step S804, a temperature distribution Tmp(p),t2 at time t2, which is the time after a predetermined period has elapsed from time t1, is read. t1 and t2 may be different from t1 and t2 in the aforementioned step S606 and T1 and T2 in FIG. 9, and may be times in the processing of the temperature change rate calculation process 800, satisfying "t1 < t2". The interval between t1 and t2 may be a time long enough to detect a temperature change caused by a fire, and may be, for example, 1 second, 5 seconds, 10 seconds, or 30 seconds. Next, in step S806, the calculation of "Tgrdnt = (Tmp(p),t2 - Tmp(p),t1) / (t2-t1)" is performed, and the processing may be ended. In step S806, the temperature change rate in an area having a certain range, for example, a high-temperature area a1, is calculated. The calculation of "Tgrdnt = (Tmp(p),t2 - Tmp(p),t1) / (t2-t1)" may be performed with the central position within the range of the high-temperature area a1 set as the reference point p. Alternatively, the position having the highest temperature within the range of the high-temperature area a1 may be set as the reference point p. Various selections may be made as to which position within the range of the high-temperature area a1 is set as the reference point p. Tgrdnt, which is the calculation result, is stored in a storage unit of the control determination unit 110.

[0065] Here, we will explain the temperature change threshold Gfire with reference to Figure 10. Figure 10 is a graph that shows the relationship between temperature detected by the temperature sensor 104 at the location of the optical fiber and time in the event of a fire in a train with a heat-generating part, with three cases superimposed. Waveform 1052 is a graph that schematically represents the temperature change during train movement. Waveform 1052 is a graph that shows the case when a train starts passing a certain point at time Ts and finishes passing at time Te. From time Ts, the temperature rises due to the heat-generating part of the train, remains constant while the train is passing, and decreases towards time Te when the train finishes passing. Waveform 1056 is a graph that schematically represents the temperature change when a fire occurs at a certain location inside a tunnel. In the case of waveform 1056, there is no train running near the fire location, and the temperature detected by the temperature sensor 104 at the fire location is not affected by the wind caused by the train running. This graph represents the case where a fire ignites at time Ts. As time passes from time Ts, the temperature rises sharply compared to waveform 1052, and after the rise, the temperature remains relatively high while fluctuating. Waveform 1054 is a schematic graph representing the temperature change when a fire occurs at a certain location inside the tunnel. In the case of waveform 1054, a train is running near the fire location, and the wind generated by the train's movement acts to lower the temperature detected by temperature sensor 104. To enable the determination of waveforms 1052, 1054, and 1056 based on the rate of temperature change after time Ts, temperature change rate thresholds 1060 and 1062 are provided. The slope corresponding to temperature change rate threshold 1060 is defined as the first temperature change rate threshold, Gfire1. The slope corresponding to temperature change rate threshold 1062 is defined as the second temperature change rate threshold, Gfire2. The rate of temperature change when a train passes is smaller than the temperature change rate threshold 1062. If a fire occurs in tunnel 120, and no trains are running near the fire's location, and the wind from passing trains does not affect the temperature sensor 104's measurement, then the rate of temperature change of the waveform 1056 due to the fire is greater than the temperature change threshold 1060.Furthermore, in the case where a fire occurs in tunnel 120, a train is running near the fire's location, and the wind generated by the train affects the temperature sensor 104's measurement, the temperature change rate of the waveform 1054 due to the fire is greater than the temperature change rate threshold 1062 and less than the temperature change rate threshold 1060. The relative magnitudes of these multiple temperature change rate thresholds in the embodiment can be selected as appropriate.

[0066] Following step S714, the process in step S716 is executed. In step S716, Tgrdnt obtained in step S806 is compared with the temperature change rate threshold Gfire2. That is, a determination is made regarding "Tgrdnt ≥ Gfire2". If the result in step S716 is Yes, the process proceeds to step S718. If the result is No, the process returns to step S702.

[0067] The process in step S718 may be the same as in step S314 in Example 1.

[0068] The processes in step S720 and step S722 may be the same as those in steps S316 and S318 in Example 1, respectively. However, if the result in each step is determined to be "No", proceed to step S740.

[0069] The process in step S716 is the same as the process in step S714, but performed for the high-temperature location a2.

[0070] The process in step S726 is the same as the process in step S716, but performed for Tgrdnt2. If the result in step S726 is Yes, proceed to step S728; otherwise, return to step S702.

[0071] If a train fire is detected in step S728 via step S726, the control determination unit 110 detects the occurrence of a fire if the temperature distribution includes a location a1 where "Tmp(p),t ≥ temperature threshold Th1", the train is traveling near the high-temperature location a1 at a speed greater than or equal to the speed threshold, the high-temperature location a1 exhibits a temperature change rate greater than the temperature change rate threshold Gfire2, the temperature distribution includes a location a2 where "Tmp(p),t ≥ temperature threshold Th2", the high-temperature location a2 is located at a position overlapping with the train's position, and the train is moving with the train at a speed greater than or equal to a predetermined speed Tspeed, and the temperature change rate at the high-temperature location a2 is greater than or equal to the temperature change rate threshold Gfire2.

[0072] The process in step S728 may be the same as the process in step S322 in Example 1. After the process in step S728 is completed, return to step S302.

[0073] Next, we will explain the process in step S730, which is performed if the result in step S710 is No and in step S712 is No. The process in step S730 is the same as the process in step S714. After the process in step S730 is completed, proceed to step S732.

[0074] The process in step S732 is the same as the process in step S716, but applied to the temperature change rate threshold Gfire1. In the process of step S732, if the determination is Yes, proceed to step S734; otherwise, return to step S702.

[0075] The process in step S734 may be the same as the process in step S332 in Example 1. After the process in step S734 is completed, return to step S702.

[0076] If step S710 is determined to be No, a tunnel fire alarm will be triggered in the following cases: The control determination unit 110 determines that a location where the temperature distribution information output from the temperature sensor 104 indicates a temperature of a predetermined first temperature threshold Th1 or higher is a high-temperature location a1, and the vibration distribution information does not detect vibrations of a vibration threshold ThV or higher in locations within a nearby threshold Lnear from high-temperature location a1, and the temperature change rate Tgrdnt1 at high-temperature location a1 is greater than or equal to the temperature change rate threshold Gfire1, then a fire alarm will be triggered. Here, in S732, an example was shown where the temperature change rate Tgrdnt1 was "greater than or equal to" the temperature change rate threshold Gfire1, but this "greater than or equal to" could also be "greater than". This is because there are large fluctuations in temperature and temperature change rate due to fire, so it is not necessary to distinguish with mathematical strictness from the threshold. In other words, when triggering a fire alarm, it is sufficient to make a determination in order to avoid danger. This is true in all embodiments of the present invention.

[0077] Next, we will explain the process in step S740, which is performed when the result in step S720 is determined to be No, and when the result in step S722 is determined to be No. The process in step S740 is the same as the process in step S724. After the process in step S740 is completed, the process proceeds to step S742.

[0078] The process in step S742 is the same as the process in step S726. If the result in step S742 is Yes, proceed to step S744; if the result is No, return to step S702.

[0079] The processing in step S744 can be the same as the processing in step S734. After the processing in step S744 is completed, return to step S702.

[0080] The following conditions trigger a tunnel fire alarm in step S744 via step S720: The control determination unit 110 determines a high-temperature location a1 when the temperature distribution information output from the temperature sensor 104 shows a temperature higher than a predetermined first temperature threshold Th1, determines a train location when the vibration distribution information output from the vibration sensor 108 shows vibrations greater than a predetermined vibration threshold ThV, and the train is moving at a predetermined speed Tspeed or higher within a nearby threshold Lnear from the high-temperature location a1, and the temperature distribution information output from the temperature sensor 104 shows a high-temperature location a2 where the temperature is above the temperature threshold Th2, and the high-temperature location a2 does not coincide with the train location, and the temperature change rate Tgrdnt2 at the high-temperature location a2 is above the temperature change rate threshold Gfire2, in which case the control determination unit detects the occurrence of a fire. As described above, the control determination unit determines the temperature distribution information acquired by the temperature sensor and the information regarding the train's running position acquired by the vibration sensor. Furthermore, the control and determination unit detects the occurrence of a fire inside the tunnel based on temperature distribution information detected by the temperature sensor and information on the train's position acquired by the vibration sensor.

[0081] According to Example 2, fires can be accurately detected even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling.

[0082] In Example 1, a modified version of Example 1, and Example 2, the temperature sensor 104 and the vibration sensor 108 may utilize optical fiber Bragg grating sensors (FBG sensors). That is, multiple FBG sensors are formed to be distributed within an optical fiber to perform distributed temperature measurement and distributed vibration measurement. In Examples 1 and 2, the temperature sensor 104 and the vibration sensor 108 may be connected using separate optical fibers to lay a multi-core optical fiber line, but the temperature sensor 104 and the vibration sensor 108 may also be connected using a single optical fiber common to both sensors. For example, an optical fiber sensor called Brillouin correlation domain reflectivity / analytic measurement (BOCDR / BOCDA) can be used.

[0083] In Example 1, a modified version of Example 1, and Example 2, the optical fiber of the temperature sensor 104 is laid at the top of the tunnel. Laying it in this way makes it easier to detect the rise in temperature due to a fire in the tunnel 120. In Examples 1 and 2, the optical fiber of the vibration sensor 108 may also be laid at the bottom of the tunnel. When laid at the bottom, existing optical fibers can be used. Laying it in this way makes it possible to detect vibrations generated by vehicles traveling through the tunnel 120. In Example 1, a modified version thereof, and Example 2, the vibration sensor may be a special case of the travel position information acquisition unit 18 described later.

[0084] [Example 3] Next, a tunnel fire detection system 11 according to Embodiment 3 of the present invention will be described. Figure 11 shows the configuration and hardware configuration of the tunnel fire detection system 11 according to Embodiment 3. The tunnel fire detection system 11 is equipped with a train position information acquisition unit 18 instead of the vibration sensor of Embodiment 1. Regarding the configuration of the tunnel fire detection system 11, the operation of the components other than the train position information acquisition unit 18 is the same as that of Embodiment 1. The operation of the components other than the train position information acquisition unit 18 will be omitted from the explanation, and the train position information acquisition unit 18 will be described. The train position information acquisition unit 18 may have the function of detecting the position in which a vehicle is traveling. The train position information acquisition unit 18 uses a vibration sensor that is different from, for example, an optical fiber distributed vibration sensor. This vibration sensor is essentially a distributed vibration sensor, with multiple vibration sensors that detect vibrations at one location arranged along the longitudinal direction of the tunnel. Various vibration sensors can be used for detecting vibrations at one location, such as vibration sensors that use acceleration measurement and vibration sensors that use displacement measurement. Multiple of these vibration sensors that detect vibrations at one location are arranged to obtain the position resolution necessary for train position detection. These multiple vibration sensors are connected to the vehicle position information acquisition unit 18 by a communication line, and the vehicle position information acquisition unit 18 is formed by these multiple sensors together. The aforementioned communication line may be wired or wireless. These multiple vibration sensors may be installed at the bottom of the tunnel, or they may be installed at the top of the tunnel together with the optical fiber 102.

[0085] As mentioned above, a method for obtaining the vibration distribution inside a tunnel when multiple vibration sensors are installed will be explained using the vibration distribution measurement process 500 shown in Figure 5. When the tunnel fire detection system 11 is activated, the control determination unit 110 may send a measurement start command to the vehicle position information acquisition unit 18. Upon receiving this measurement start command, the vehicle position information acquisition unit 18 may send a measurement start command to all vibration sensors installed inside the tunnel. Each vibration sensor that receives the measurement start command may measure the vibration at that time and send the measurement result to the vehicle position information acquisition unit 18. Upon receiving the vibration measurement results from each vibration sensor, the vehicle position information acquisition unit 18 can obtain the vibration distribution Vbrtn(p),t by combining the pre-set position information of each vibration sensor with the vibration information measured by each sensor, and may save this vibration distribution. This series of processes may be performed in step S502.

[0086] As described above, in Example 3, the same vibration distribution Vbrtn(p),t as in Examples 1 and 2 can be obtained. The algorithm for detecting a fire in the tunnel may be the same as that of Example 1, a modified version of Example 1, and Example 2.

[0087] According to Example 3, fires can be accurately detected even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling.

[0088] [Example 4] Next, a tunnel fire detection system 11 according to Embodiment 4 of the present invention will be described. Figure 11 shows the configuration and hardware configuration of the tunnel fire detection system 11 according to Embodiment 4. The tunnel fire detection system 11 differs from Embodiment 1 in that the vibration sensor 108 has been replaced with a driving position information acquisition unit 18. The rest of the configuration of the tunnel fire detection system 11 is the same as that of Embodiment 1.

[0089] Regarding the configuration of the tunnel fire detection system 11, the operation of the components other than the train position information acquisition unit 18 is the same as in Embodiment 1. The operation of the components other than the train position information acquisition unit 18 will be omitted from this explanation, and the train position information acquisition unit 18 will be described. The train position information acquisition unit 18 may have a function to detect the position in which a vehicle is traveling. The train position information acquisition unit 18 may, for example, acquire the train's position from a track signaling system that detects the position in which a train is traveling in a railway system. The track signaling system is a system that detects the train's position in real time, and it is acceptable for it to detect the absolute position of the train and the relative position that detects where the train is traveling relative to a certain starting point, as long as the train's position can be identified. The track signaling system may detect the train's position by detecting when a train passes over a device installed on the ground. The track signaling system may also utilize a positioning system, such as the GNSS (Global Navigation Satellite System). Furthermore, various signaling systems can be used for the railway lines, including those utilizing track circuits, crossing guide lines, treadles, and check-in / check-out systems.

[0090] The signaling system for the route illustrated in Figure 11 illustrates examples of systems that detect the train's position by detecting when a train passes over a device 16 installed on the ground, such as those that utilize the aforementioned track circuits and those that use crossing guide lines. Through the various configurations described above, the signaling system detects the position of at least the train 912 traveling inside the tunnel 120.

[0091] Next, the mechanism by which the tunnel fire detection system 11 according to Example 4 detects a fire inside a tunnel will be explained using diagrams. In Example 4, as in Example 1, a tunnel 120 on which a train runs will be used as an example. The train will be described as having equipment that generates heat, such as drive motors and braking systems. In the explanation of Example 4, explanations that are the same as in Example 1 will be omitted.

[0092] In the description of the tunnel fire detection system 11, the optical fiber distributed temperature sensor 104 will simply be referred to as the temperature sensor 104. When the tunnel fire detection system 11 is activated, the control determination unit 110 may send a measurement start command to the temperature sensor 104 and the vehicle position information acquisition unit 18. Upon receiving this measurement start command, the temperature sensor 104 and the vehicle position information acquisition unit 18 may start measuring according to the flow shown in Figures 4 and 14.

[0093] As in Example 1, the temperature sensor 104 may receive the aforementioned measurement start command and perform processing according to the temperature distribution measurement process 400 shown in Figure 4. The explanation of the temperature distribution Tmp(p) and t in that case is also the same.

[0094] When the train position information acquisition unit 18 receives the aforementioned measurement start command, it may acquire the train position information Train(p),t in step S52 according to the train position information acquisition process 50 shown in Figure 14, and store the acquired information in a storage unit within the train position information acquisition unit 18. In the recorded train position information Train(p),t, t may be the time when the acquisition of the train position information began, and Train(p),t is information that includes the train position information of position p at time t. Here, p may be the position inside the tunnel 120.

[0095] The train position information acquisition unit 18 may send a measurement completion signal to the control determination unit 110 once the train position information Train(p),t has been stored. After receiving the measurement start command, if necessary, it may perform the signal-to-noise ratio (S / N) improvement process described in Example 1. This signal-to-noise ratio (S / N) improvement process may be treated as a single measurement for the train position information Train(p),t, just as in the case of the temperature sensor.

[0096] When the control determination unit 110 receives measurement completion signals from both the temperature sensor 104 and the driving position information acquisition unit 18, it sends a measurement command to both the temperature sensor 104 and the driving position information acquisition unit 18 again. With this configuration, the temperature sensor 104 and the driving position information acquisition unit 18 perform measurements at the same time, and information for the same time period can be obtained for the temperature distribution information obtained from the temperature sensor 104 and the vibration information obtained from the vibration sensor 108. By controlling the temperature sensor 104 and the driving position information acquisition unit 18 in this way, the same effects as those described for the temperature sensor 104 and vibration sensor 108 in Embodiment 1 are achieved.

[0097] Next, the fire detection process of Example 4 will be explained using Figure 12. The flowchart example for the fire detection process of Example 4 is the same as in Figure 3, except that the process at step S304 is "reading the travel position information Train(p),t". In flowchart example 1300 of Example 4, this will be represented as step S1302. As mentioned above, in flowchart example 1300, the process step S1304 corresponding to step S304 is "reading the travel position information Train(p),t".

[0098] Flowchart Example 1300 of Embodiment 4 will be explained. In this explanation, the same processes as those explained in Flowchart Example 300, which corresponds to Flowchart Example 1300, will be omitted, and the different processes will be mainly explained. In the tunnel fire detection system 11, when the fire detection flowchart Example 1300 is activated in the control determination unit 110, step S1302 "Read temperature distribution Tmp(p),t" is executed. Next, step S1304 "Read running position information Train(p),t" is executed. The running position information Train(p),t read here is information acquired and stored in the running position information acquisition process 50, and may be at the time corresponding to the temperature distribution Tmp(p),t read in step S1302. However, it is preferable that the Train(p),t read in step S1304 be the latest information acquired, measured and stored in the running position information acquisition process 50. Since the temperature distribution measurement process 400 and the train position information acquisition process 50 are performed in a sufficiently short time compared to the time it takes for a fire to spread, the latest temperature distribution Tmp(p),t and the latest train position information Train(p),t can be treated as being from essentially the same time.

[0099] Following step S1304, step S1306 executes the "train position, speed, etc. detection" process. The specific processing in step S1306, "train position, speed, etc. detection," may be the same as that shown in Figure 6, which was explained in Example 1. However, the processing content differs in each step from that explained in Example 1, so these differences will be explained. In this embodiment, "train position, speed, etc. detection" is shown in Figure 13 as train position, speed, etc. detection 1600.

[0100] In the train position and speed detection 1600, first in step S1602, it is determined whether a train is inside the tunnel. In this determination, the latest running position information Train(p),t saved in the running position information acquisition process 50 is first read. From the read Train(p),t, the location b of the train may be determined. The coordinates of both ends of location b are Pb1 and Pb2, provided that "Pb2 > Pb1". If at least one of the coordinates Pb1 and Pb2 is within the coordinates Pstart and Pend of both ends of the tunnel, it may be determined that a train is inside the tunnel. The coordinates of location b are stored in the memory of the control determination unit 110.

[0101] In step S1602, if no train presence is detected, the process proceeds to No in step S1602, and the train position and speed detection 1600 process is completed. A train presence flag may be prepared, and if no train presence is detected, the flag may be set to "not present". In step S1602, if a train presence is detected, the process proceeds to Yes. Here, if a train presence is detected, the aforementioned train presence flag may be set to "present". The train presence flag may also be used to determine whether a train is inside a tunnel.

[0102] Next, in step S1604, the train's position is obtained from the signal system to detect its location. Then, in step S1606, the train's speed and direction of movement are detected. In step S1606, the train's position information Train(p),t at time t2, which is a predetermined time after the measurement time t1 of the position information Train(p),t read in step S1602, is read, and a new train position is detected from this newly read position information. The direction of travel information of the train can be obtained by taking the difference between this new train position and the previous train position. In addition, the speed information of the train can be obtained by dividing the difference between the new train position and the previous train position by the time (t2-t1). The speed information of the train obtained here is called Vtrain,t, and Vtrain,t can be stored in the memory of the control determination unit 110. In Vtrain,t, "t" is the time when the position information Train(p),t from which the speed information was obtained was acquired, for example, t1.

[0103] Furthermore, in the train position and speed detection 1600, step S1608 "Detection of train stopping inside a tunnel" detects whether the train has stopped inside a tunnel. In this detection of train stopping inside a tunnel, it is preferable to determine that the train has stopped when the train's speed becomes 0, based on the changes in the train's speed information obtained sequentially as described above. Note that the processing in step S1608 "Detection of train stopping inside a tunnel" may be performed as a separate, independent process from the train position and speed detection 1600. By making it an independent process, the processing time of the train position and speed detection 1600 itself can be shortened. The train stopping position information can be used to determine whether the train is in a safe location or a dangerous location when a fire is detected, as will be described later.

[0104] The process from step S1308 to step S1316, following step S1306, is the same as that described in steps S308 to S316 in Example 1. In this description, the step codes should be understood by replacing the three-digit codes in Example 1 with the corresponding four-digit codes in Example 4.

[0105] The process of step S1318 will now be explained. In step S1318, it is determined whether the high-temperature location a2 detected in step S1314 is moving with the train. In this determination, the high-temperature location a2 and the train position are determined from the temperature distribution Tmp(p),t data and the train position information Train(p),t acquired at a certain time, and a new high-temperature location a2 and a new train position are determined from the temperature distribution Tmp(p),t data and the train position information Train(p),t data at a time predetermined time after that time, and the relationship between the coordinates of the high-temperature location a2 and the coordinates of the train position at both times may be determined. For example, it may be determined whether the difference between the smaller coordinate of the train position and the smaller coordinate of the high-temperature location a2 at both times is within a predetermined error. If this difference is within a predetermined error, it may be determined that "location a2 is moving with the train". The predetermined time in the aforementioned "time predetermined time after" may be, for example, 0.1 seconds, 0.2 seconds, 0.5 seconds, or 1 second. Furthermore, the aforementioned "predetermined error" should be set according to the speed of the train in motion and the condition of the fire that occurs. If the result in step S1318 is Yes, proceed to step S1320; if the result is No, proceed to step S1330.

[0106] Regarding the flowchart example 1300 of Example 4, the processes other than those described above are the same as the corresponding processes described in Example 1.

[0107] Next, a modified example of Example 4 will be described. In the modified example of Example 4, the tunnel fire detection system 11 of Example 4 is configured to detect tunnel fires and train fires using the rate of temperature change instead of the temperature threshold used in the modified example of Example 1. The fire detection process in the modified example of Example 4 is the same as that in the modified example of Example 1.

[0108] Further, a different modification of Example 4 will be described. This different modification of Example 4 uses the fire detection processing of Example 2 in the configuration of the tunnel fire detection system 11 of Example 4. In this different modification of Example 4, the processing related to the train position information Train(p) and t may be the same as that of Example 4.

[0109] According to Example 4, its modifications, and other modifications, fires can be accurately detected even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling.

[0110] As described above, various embodiments and modifications have been explained. The configurations and various determination processes described in those embodiments can be incorporated into or combined with the processes of other embodiments and modifications. In the flowchart example described above, various steps were mentioned, but the order of these steps is not fixed, and the order and combination can be freely changed within the scope of the present invention. Even in tunnels where moving objects with heat sources, such as trains and automobiles, are traveling, fire can be accurately detected.

[0111] In the various embodiments and modifications described above, a process for determining when a train has stopped may be performed. The train's stopped state may be determined using the aforementioned train position, speed, etc. detection process, and the stopping position may be stored in memory. Fire detection may also be performed when the train starts moving again. For example, in Embodiments 1 and 2 and their modifications, the temperature distribution measurement process and the vibration distribution measurement process are performed as temperature distribution measurement process 400 and vibration distribution measurement process 500, respectively, as processes independent of the fire detection flowchart example 300, but these measurement processes may also be performed within the fire detection flowchart. In the processes of the embodiments, abnormal processing may be performed when various data, such as temperature distribution Tmp(p),t and vibration distribution Vbrtn(p),t data, contain abnormal information. In Embodiments 1 and 2, the fire detection process is repeatedly executed, and train fire alarms and tunnel fire alarms are executed sequentially. However, once a fire alarm is triggered, the system may be configured to continue the alarm state. In that case, it would be desirable to add an alarm state reset function to stop the fire alarm. The same applies to Embodiments 3 and 4 and their modifications.

[0112] Although the present invention has been described in detail with reference to the accompanying drawings, the present invention is not limited to such specific configurations and includes various modifications and equivalent configurations within the spirit of the attached claims. Furthermore, the present invention is not limited to the embodiments described above, and in practice, the components can be modified and implemented without departing from the spirit of the invention. [Explanation of Symbols]

[0113] 18. Unit for acquiring driving location information 101...Tunnel Fire Detection System 102, 106, 210, 240... Fiber optics 104...Temperature sensor 108...Vibration sensor 110...Control and Judgment Unit

Claims

1. A fire detection system for triggering an alarm for a fire in a tunnel through which a vehicle having a heat-generating component can pass, A distributed optical fiber temperature sensor detects light propagating through an optical fiber laid along the longitudinal direction of the tunnel on the inner wall surface to measure the temperature distribution inside the tunnel, A unit for acquiring driving position information that acquires the driving position of the vehicle inside the tunnel, It comprises a control unit and, The fire detection system is characterized in that, when the control unit determines that there is a first high-temperature location based on the measured temperature distribution, and determines that the vehicle's position is not within a predetermined distance from the first high-temperature location, it issues an alarm indicating the occurrence of a fire in the tunnel.

2. A fire detection system according to claim 1, A fire detection system characterized in that the optical fibers of the optical fiber distributed temperature sensor are laid in the upper part of the tunnel.

3. A fire detection system according to claim 1, The fire detection system is characterized in that the control unit determines a location to be the first high-temperature location when there is a location in the temperature distribution that shows a temperature of a predetermined first temperature threshold or a location that shows a temperature change rate of a predetermined first temperature change rate threshold or higher.

4. A fire detection system according to claim 1, The control unit, If, based on the measured temperature distribution, it is determined that there is a first high-temperature location, and it is determined that the vehicle's position is within a predetermined distance from the first high-temperature location, and it is determined that the vehicle's speed is greater than or equal to a predetermined speed, and if there is a location in the temperature distribution that shows a temperature of a predetermined second temperature threshold or a location that shows a temperature change rate of a predetermined second temperature change rate threshold or greater, then that location is determined to be a second high-temperature location. A fire detection system characterized by triggering an alarm for the occurrence of a fire in the tunnel when it is determined that the second high-temperature location does not coincide with the vehicle's travel position.

5. A fire detection system according to claim 1, The control unit, If, based on the measured temperature distribution, it is determined that there is a first high-temperature location, and it is determined that the vehicle's position is within a predetermined distance from the first high-temperature location, and it is determined that the vehicle's speed is greater than or equal to a predetermined speed, and if there is a location in the temperature distribution that shows a temperature of a predetermined second temperature threshold or a location that shows a temperature change rate of a predetermined second temperature change rate threshold or greater, then that location is determined to be a second high-temperature location. A fire detection system characterized by triggering an alarm for the occurrence of a fire in the vehicle when it is determined that the second high-temperature location coincides with the vehicle's driving position, the second high-temperature location is moving along with the vehicle's position, and the measured temperature distribution contains a location with a temperature above a predetermined third temperature threshold.

6. A fire detection system according to claim 1, The control unit, If, based on the measured temperature distribution, it is determined that there is a first high-temperature location, and it is determined that the vehicle's position is within a predetermined distance from the first high-temperature location, and it is determined that the vehicle's speed is greater than or equal to a predetermined speed, and if there is a location in the temperature distribution that shows a temperature of a predetermined second temperature threshold or a location that shows a temperature change rate of a predetermined second temperature change rate threshold or greater, then that location is determined to be a second high-temperature location. A fire detection system characterized by triggering an alarm for the occurrence of a fire in the tunnel when it is determined that the second high-temperature location coincides with the vehicle's travel position, that the second high-temperature location has not moved with the vehicle's position, and that there is a location in the measured temperature distribution that shows a temperature of a predetermined third temperature threshold or higher.

7. A fire detection system according to any one of claims 1 to 6, wherein the travel position information acquisition unit is composed of an optical fiber distributed vibration sensor that detects light propagating inside an optical fiber and measures vibration.

8. A fire detection system according to claim 7, A fire detection system characterized in that the optical fiber distributed temperature sensor and the optical fiber distributed vibration sensor are configured using a single common optical fiber.

9. A fire detection system according to any one of claims 1 to 6, The fire detection system is characterized in that the vehicle's location information acquisition unit acquires information regarding the vehicle's location from the route's signaling system.

10. A fire detection method performed by a fire detection system that triggers an alarm for a fire in a tunnel through which a vehicle having a heat-generating part can pass, The aforementioned fire detection system, A distributed optical fiber temperature sensor detects light propagating through optical fibers laid along the longitudinal direction of the tunnel on the inner wall surface, thereby measuring the temperature distribution inside the tunnel. The vehicle's position is obtained, A fire detection method characterized in that, when it is determined that there is a first high-temperature location in the measured temperature distribution, and it is determined that the vehicle's position is not within a predetermined distance from the first high-temperature location, an alarm is issued indicating the occurrence of a fire in the tunnel.

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