JP5995496B2 - Fire alarm and fire judgment method - Google Patents

Description

  The present invention relates to a fire alarm and a fire determination method.

  Conventionally, there has been proposed a fire alarm that detects each of heat, smoke, and carbon monoxide (hereinafter also referred to as CO), and detects these in a complex manner (see, for example, Patent Document 1). . According to this fire alarm, it is possible to improve the accuracy of fire detection by paying attention to the fact that heat, smoke and CO are generated in the event of a fire.

JP 2007-316765 A

  Here, there is a fire called firewood fire caused by the mismanagement of cigarettes. However, this smoldering fire is sometimes called a flameless fire, and there is a tendency that heat and smoke do not generate much. It is difficult to make a judgment of a fire.

  The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide a fire alarm capable of determining a fire burning based on a signal from a CO sensor, and It is to provide a fire judgment method.

The fire alarm of the present invention includes a CO sensor that outputs a signal corresponding to the surrounding carbon monoxide concentration, a determination unit that determines a fire based on the signal from the CO sensor, and a fire that is determined by the determination unit. A fire alarm unit that issues a fire alarm in the case of, and storage means for storing data of arrival time until the blood carbon monoxide hemoglobin concentration corresponding to various carbon monoxide concentrations reaches a predetermined value, Based on the signal from the CO sensor and the storage content of the storage means , the determination unit determines whether the blood carbon monoxide hemoglobin concentration after the carbon monoxide concentration based on the signal from the CO sensor becomes equal to or greater than a specific value. There characterized by determining that Ibushisho fire when the duration until it is determined that reached the predetermined value becomes the prescribed time or more has occurred.

  According to this fire alarm device, it is determined that a smoldering fire has occurred when the duration of time until the blood carbon monoxide hemoglobin concentration reaches a predetermined value is longer than a specified time. Here, the present inventors have found a tendency for CO to gradually increase in the low concentration region in the early and middle stages of the smoldering fire. For this reason, when a smoldering fire occurs, the duration of time until the blood carbon monoxide hemoglobin concentration reaches a predetermined value is longer than the specified time due to the gradual increase of CO in the low concentration region. Therefore, it is possible to determine a smoldering fire based on the signal from the CO sensor.

The fire determination method of the present invention includes a determination step of determining a fire based on a signal from a CO sensor that outputs a signal corresponding to the surrounding carbon monoxide concentration, and a case where a fire is determined in the determination step. A fire alarm step for issuing a fire alarm, and in the determination step, the time until the blood carbon monoxide hemoglobin concentration reaches a predetermined value according to the signal from the CO sensor and various carbon monoxide concentrations the data based on the stored contents of the stored storage means, from when the carbon monoxide concentration based on the signal from the CO sensor-specific value or more, a carbon monoxide hemoglobin concentration in blood has been reached to a predetermined value it is determined that Ibushisho fire is occurring when the duration until the judgment becomes prescribed time or more, characterized in.

  According to this fire determination method, it is determined that a smoldering fire has occurred when the duration of time until the blood carbon monoxide hemoglobin concentration reaches a predetermined value is longer than a specified time. Here, the present inventors have found a tendency for CO to gradually increase in the low concentration region in the early and middle stages of the smoldering fire. For this reason, when a smoldering fire occurs, the duration of time until the blood carbon monoxide hemoglobin concentration reaches a predetermined value is longer than the specified time due to the gradual increase of CO in the low concentration region. Therefore, it is possible to determine a smoldering fire based on the signal from the CO sensor.

  According to the fire alarm and the fire determination method of the present invention, it is possible to determine a smoldering fire.

It is the schematic of the fire alarm device which concerns on embodiment of this invention. It is a graph which shows the CO density | concentration after a firewood fire occurrence, and has shown the initial stage of a firewood fire. It is a graph which shows the CO density | concentration after a firewood fire outbreak, and has shown the middle term of the firewood fire. It is a graph which shows CO density | concentration and smoke density | concentration after a firewood fire occurrence, and has shown the case where the firewood fire of FIG. 3 advances. It is a 1st graph which shows CO concentration in the 2nd floor at the time of the fire outbreak on the 1st floor. It is a 2nd graph which shows the CO density | concentration in the 2nd floor at the time of the fire outbreak on the 1st floor. It is a flowchart which shows the fire judgment method of the fire alarm device which concerns on this embodiment, Comprising: The 1st method is shown. It is a flowchart which shows the fire judgment method of the fire alarm device which concerns on this embodiment, Comprising: The 2nd method is shown.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a schematic view of a fire alarm device according to an embodiment of the present invention. The fire alarm device 1 shown in FIG. 1 detects a fire when a fire occurs in a living room or the like, and alerts the fire. For example, the fire alarm 1 is installed in a ceiling part of a space such as a living room. Note that the fire alarm device 1 according to the present embodiment can be installed not only on the ceiling but also on any place such as a wall or a floor surface.

  Such a fire alarm device 1 includes a CO sensor 10, a heat sensor 20, a smoke sensor 30, a CPU (determination unit) (Central Processing Unit) 40, and a voice alarm unit (fire alarm unit) 50. ing.

  The CO sensor 10 outputs a signal corresponding to the surrounding carbon monoxide concentration. Specifically, the CO sensor 10 is an electrochemical sensor in which a current corresponding to the CO concentration flows due to the oxidation reaction of CO, converts the current corresponding to the CO concentration into a voltage, and outputs the voltage to the CPU 30.

  The thermal sensor 20 outputs a signal corresponding to the temperature. Specifically, the thermal sensor 20 includes a thermistor whose resistance value varies depending on the ambient temperature, and outputs a temperature signal corresponding to the ambient temperature based on this resistance value.

  The smoke sensor 30 outputs a signal corresponding to the amount of smoke. Specifically, the smoke sensor 30 includes a photoelectric element that outputs a light amount signal corresponding to a light amount on a predetermined optical path.

  The CPU 40 controls the entire fire alarm device 1. The CPU 40 has a determination function (determination unit) that determines a fire based on signals from the sensors 10 to 30.

  The sound alarm unit 50 issues a fire alarm when a fire is determined by the CPU 40, and includes, for example, a sound output circuit and a sound output unit such as a speaker or a buzzer.

  Here, the conventional fire alarm has only a function of judging a complex fire based on signals from the sensors. However, there is a fire that is fired due to mismanagement of cigarettes. This smoldering fire is sometimes called a flameless fire and tends to generate less heat and smoke. For this reason, in the conventional fire alarm device, it is difficult to make a judgment of a smoldering fire based on heat, smoke and CO.

  However, as a result of intensive studies on the fire situation, the present inventors have found a tendency for CO to gradually increase in the low concentration region in the early and middle stages of the fire. Therefore, the inventors of the present invention not only determine a complex fire based on the signals from the sensors 10 to 30, but also based on the signal from the CO sensor 10, the smoldering fire is performed by the first method and the second method. Led to the development of a fire alarm 1 that detects the occurrence of fire.

  The first method will be described. The CPU 40 of the fire alarm device 1 according to the present embodiment determines that a smoldering fire has occurred when the CO concentration within a predetermined concentration range continues for a predetermined time based on a signal from the CO sensor 10.

  More specifically, the CPU 40 stores a first predetermined density range and a second predetermined density range whose lower limit value is higher than the upper limit value of the first predetermined density range. Then, the CPU 40 determines that it is the initial stage of the smoldering fire when the CO concentration within the first predetermined concentration range continues for the first predetermined time. Further, the CPU 40 determines that the smoldering fire is continuing (medium term) when the CO concentration within the second predetermined concentration range continues for the second predetermined time. The lower limit value of the second predetermined density range is higher than the upper limit value of the first predetermined density range.

  FIG. 2 is a graph showing the CO concentration after the occurrence of the smoldering fire, and shows the initial stage of the smoldering fire. First, it is assumed that a fire broke out at elapsed time 0. At this time, as shown in FIG. 2, the CO concentration increases from about 4 minutes after the occurrence of the smoldering fire. For example, at a position of 225 cm from the floor, it reaches 20 ppm at about 10 minutes from the occurrence of the smoldering fire, and reaches 60 ppm at about 16 minutes. Further, for example, at a position 30 cm from the floor, it reaches 20 ppm at about 13 minutes from the occurrence of the fire, and reaches 35 ppm at about 16 minutes. In both cases, the CO concentration of 20 ppm or more was maintained at 18 minutes.

  In this way, CO is gradually increased in the low concentration region in the initial stage of fire occurrence in the fire. Therefore, the CPU 40 determines that a smoldering fire has occurred when the CO concentration within the first predetermined concentration range continues for the first predetermined time based on the signal from the CO sensor 10.

  In the present embodiment, the first predetermined concentration range is a range of 20 ppm or more and less than 50 ppm. That is, in the present embodiment, the CPU 40 determines that a smoldering fire has occurred when a CO concentration of 20 ppm or more and less than 50 ppm is detected for the first predetermined time. The first predetermined concentration range is not limited to the above as long as it is a range of 100 ppm or less, for example, in which the blood carbon monoxide hemoglobin concentration (hereinafter also referred to as COHb concentration) in the human body is assumed not to increase so much. This is because by setting in such a range, an alarm can be issued before the influence on the human body becomes clear, and the user can be prompted to respond. In the present embodiment, the first predetermined time is set to 5 minutes, for example, but is not limited to this, and can be changed as appropriate.

  FIG. 3 is a graph showing the CO concentration after the occurrence of the smoldering fire, and shows the middle stage of the smoldering fire. Note that the graph shown in FIG. 3 is measured in an environment different from that of the graph shown in FIG. 2, and the phenomenon does not necessarily coincide with the graph shown in FIG.

  First, it is assumed that a fire broke out at elapsed time 0. At this time, as shown in FIG. 3, for example, at a position 230 cm from the floor, the CO concentration gradually increases from the occurrence of the smoldering fire, and reaches 20 ppm at about 20 minutes. Thereafter, the CO concentration continues to increase, reaching 50 ppm at about 40 minutes, and then rising in a quadratic curve to about 170 ppm at 60 minutes.

  In addition, the CO concentration at a position 150 cm from the floor is approximately 0 ppm at about 30 minutes from the occurrence of the smoldering fire, but from this point on, the CO concentration rises in a quadratic curve and reaches about 40 minutes. Then, it rises to 30 ppm. Thereafter, the CO concentration increases, reaching 110 ppm at about 50 minutes, and reaching about 200 ppm at about 60 minutes.

  In addition, the CO concentration at the position 30 cm from the floor is approximately 0 ppm until just before 30 minutes have elapsed since the occurrence of the smoldering fire, but from this point on, the CO concentration increases in a quadratic curve and is about 30 minutes. It rises to 20 ppm at the time. Thereafter, the CO concentration increases and reaches 110 ppm to 130 ppm at about 40 to 60 minutes.

  As described above, in the case of firewood fire, CO tends to increase from a low concentration to a quadratic curve in the middle stage of the fire. Therefore, in order to capture this tendency, the CPU 40 is continuing (medium-term) fire when the CO concentration within the second predetermined concentration range continues for the second predetermined time based on the signal from the CO sensor 10. Judge.

  In the present embodiment, the second predetermined concentration range is a range of 50 ppm or more and less than 100 ppm. That is, in the present embodiment, the CPU 40 determines that the smoldering fire is ongoing when a CO concentration of 50 ppm or more and less than 100 ppm is detected for the second predetermined time. The second predetermined concentration range is not limited to the above as long as it is a range of 100 ppm or less, like the first predetermined concentration range. In the present embodiment, the second predetermined time is set to, for example, 5 minutes, but is not limited thereto, and can be changed as appropriate.

  FIG. 4 is a graph showing the CO concentration and smoke concentration after the occurrence of the smoldering fire, and shows the case where the smoldering fire of FIG. 3 has progressed. As shown in FIG. 4, the smoke concentration rapidly rises when about 90 minutes have elapsed since the occurrence of the fire. For this reason, in the conventional fire alarm which judges a fire in combination from heat, smoke, and CO, there is a high possibility that a fire will be judged and alarmed at the point of 90 minutes.

  However, at this 90 minute point, the CO concentration is about 900 ppm at 230 cm from the floor, 850 ppm at 150 cm, and 550 ppm at 30 cm. For this reason, the CO concentration far exceeds 100 ppm, which is assumed that the COHb concentration of the human body does not increase so much, and even if an alarm is given at this time, there is a high possibility that the user will not be encouraged to take an appropriate action. .

  On the other hand, in the fire alarm device 1 according to the present embodiment, the CPU 40 is the initial stage of the smoldering fire when the CO concentration of 20 ppm or more and less than 50 ppm is detected for the first predetermined time (5 minutes) as described above. Judge. In addition, the CPU 40 determines that it is in the middle of the smoldering fire when a CO concentration of 50 ppm or more and less than 100 ppm is detected for the second predetermined time (5 minutes). Therefore, compared with a fire alarm device that determines a fire in combination from heat, smoke, and CO, it is possible to determine a smoldering fire at an early stage, and prompt the user to take an appropriate response.

  In the present embodiment, it is preferable to change the alarm output between the initial stage and the middle stage of the smoldering fire. For example, when the CPU 40 determines the initial stage of the smoldering fire, the voice alarm unit 50 outputs “Are there any smoldering in the room or in the next room? Check the source of the fire.” When it is judged, it outputs “There may be a fire in the room or in the next room. Check the room and the source of the fire.” This is because, for example, the latter can output an alarm with a higher degree of danger than the former, and can perform a step-by-step alarm about a fire.

  Further, in the present embodiment, the CPU 40 has a function of determining when a smoldering fire in another room has progressed to become a normal fire. 5 and 6 are graphs showing the CO concentration on the second floor when a fire occurs on the first floor.

  As shown in FIG. 5, when a fire occurs on the first floor, the CO concentration on the second floor gradually increases from the time of the first floor fire, and reaches about 80 ppm at about 24 minutes from the occurrence of the fire. Further, as shown in FIG. 6, the CO concentration rapidly increases from this point, exceeds 500 ppm at about 25 minutes from the occurrence of the fire, and reaches 2000 ppm at about 26 minutes. As described above, the present inventors, when a fire has occurred in another room, will give a fire alarm after a certain amount of time due to the hot air current in the other room (including flashover and backdraft). It has been found that the CO concentration tends to increase rapidly in the room where the vessel 1 is installed.

  Therefore, the CPU 40 determines that a fire has occurred in another room when the degree of increase in the CO concentration is equal to or greater than the predetermined degree of increase in the concentration region exceeding 100 ppm (predetermined concentration range). Here, the case where the increase degree of the CO concentration is equal to or higher than the predetermined increase degree means a case where, for example, the CO concentration increases by 20 ppm or more in 10 seconds. Thus, in this embodiment, CPU40 can judge the fire of another room by performing the judgment reflecting the said tendency.

  5 and 6, the downstairs room has been described as an example of another room. However, the present invention is not limited to this. For example, all rooms in the same building such as a neighboring room are not limited to downstairs rooms. Absent. Moreover, since the fire alarm device 1 according to the present embodiment can determine a fire in another room, the fire alarm in the other room can be accurately determined from the determination results of the fire alarm device 1 in itself and the other room. You can also

  Furthermore, when the fire alarm device 1 according to the present embodiment determines a fire in another room, it is preferable to change the alarm contents step by step. More specifically, the CPU 40 determines that the first fire alarm is output when there is a concentration increase of 20 ppm or more in 10 seconds in a concentration range of 100 ppm or more and less than 200 ppm. Then, the voice alarm unit 50 warns, for example, “There may be a fire in the room or in the adjacent room. Please check the room and the source of the fire promptly” (first fire alarm).

  Further, the CPU 40 determines that the second fire alarm is output when the concentration rises by 20 ppm or more in 10 seconds in the concentration range of 200 ppm or more. Then, the voice alarm unit 50 warns, for example, “There may be a fire in the room or in the adjacent room. Please evacuate immediately.” (Second fire alarm).

  If the CPU 40 detects a CO concentration of 500 ppm or more, regardless of the degree of increase in the CO concentration, the voice alarm unit 50 may indicate, for example, “A fire may have occurred in the room or in the adjacent room. When the CO concentration of 1000 ppm or more is detected, the voice alarm unit 50 outputs, for example, “Fire. Please evacuate immediately” (Fourth fire alarm).

  Next, the second method will be described. In addition to the first method, the fire alarm device 1 according to the present embodiment has a function of performing a fire detection according to the COHb concentration. Hereinafter, fire detection according to the COHb concentration will be described.

  In this function, the CPU 40 determines the arrival time T at which the COHb concentration reaches a predetermined value from the CO concentration based on the signal from the CO sensor 10, and integrates the reciprocal of the arrival time T to determine the fire. .

  More specifically, for example, at an oxygen concentration of 18%, when the human body is exposed to 300 ppm of CO, COHb = 10% after 14.54 minutes, and when exposed to 400 ppm of CO, after 10.07 minutes, COHb = 10%. In the present embodiment, the CPU 40 stores such data. The stored data is not limited to the oxygen concentration of 18% but may be 21% or the like. Further, the COHb concentration is not limited to 10%, and may be 20% and 30%.

  Further, when 300 ppm of CO is detected for 1 minute, the CPU 40 integrates 1 / 14.54 as the reciprocal of the arrival time T. Further, when 400 ppm of CO is detected for 5 minutes after 300 ppm of CO is detected for 1 minute, 5 / 10.07 is integrated as the reciprocal of the arrival time T. In this way, the CPU 40 sequentially accumulates, and when the accumulated value becomes 1 or more, the CPU 40 determines that the COHb concentration has reached 10% and determines that a fire has occurred.

  Furthermore, in this embodiment, a fire is fired when the integration time starts and the integrated value becomes 1 and the duration until it is determined that a fire has occurred is longer than a specified time (for example, 30 minutes). If the duration is less than the specified time, it is determined that another fire has occurred. As described above, low concentration of CO is generated at the beginning of the fire, and then the CO concentration rises rapidly. Therefore, the integration time becomes 1 and the duration until it is determined that a fire has occurred is the specified time. That's it. Therefore, in such a case, it is determined that it is a smoldering fire.

  In addition, about the integration of the reciprocal of arrival time T, you may weight according to CO density | concentration, and you may consider the delay time by the case of the fire alarm device 1. FIG. Further, the integrated value may be corrected, or the integrated value may be reset when the CO concentration becomes lower than the specific value. Further, the integration is started when the CO concentration becomes a specific value or more, and the integration may not be performed when the CO concentration is less than the specific value.

  Next, the fire determination method of the fire alarm device 1 according to the present embodiment will be described with reference to a flowchart. FIG. 7 is a flowchart showing a fire determination method of the fire alarm device 1 according to the present embodiment, and shows a first method.

  As shown in FIG. 7, the CPU 40 first detects the CO concentration based on the signal from the CO sensor 10 (S1). Next, the CPU 40 determines whether or not the detected CO concentration is 20 ppm (lower limit value of the first predetermined concentration range) or more (S2). When it is determined that the CO concentration is not 20 ppm or more (S2: NO), the process proceeds to step S1.

  On the other hand, when it is determined that the CO concentration is 20 ppm or more (S2: YES), the CPU 40 determines whether or not the detected CO concentration is 50 ppm (lower limit value of the second predetermined concentration range) or more (S3). . When it is determined that the CO concentration is not 50 ppm or more (S3: NO), the CPU 40 determines whether or not the CO concentration of 20 ppm or more and less than 50 ppm has continued for the first predetermined time (S4).

  If it is determined that the first predetermined time has not been continued (S4: NO), the process proceeds to step S1. If it is determined that the first predetermined time has been continued (S4: YES), the CPU 40 determines that it is the initial stage of the smoldering fire and causes the voice alarm unit 50 to output a first smoldering fire alarm (S5). At this time, the voice alarm unit 50 outputs “Does the room or the adjacent room have a slap? Check the source of the fire.” Thereafter, the process shown in FIG. 7 ends.

  When it is determined that the CO concentration is 50 ppm or more (S3: YES), the CPU 40 determines whether the detected CO concentration is 100 ppm or more (exceeds the upper limit value of the second predetermined concentration range) (S6). . When it is determined that the CO concentration is not 100 ppm or more (S6: NO), the CPU 40 determines whether or not the CO concentration of 50 ppm or more and less than 100 ppm has continued for the second predetermined time (S7).

  If it is determined that the second predetermined time has not been continued (S7: NO), the process proceeds to step S1. When it is determined that the second predetermined time is continued (S7: YES), the CPU 40 determines that the fire is in the middle stage and causes the voice alarm unit 50 to output the second fire fire alarm (S8). At this time, the voice alarm unit 50 outputs “There is a risk of fire in the room or in the next room. Check the room and the source of the fire.” Thereafter, the process shown in FIG. 7 ends.

  When it is determined that the CO concentration is 100 ppm or more (S6: YES), the CPU 40 determines whether or not the detected CO concentration is 200 ppm or more (S9). When it is determined that the CO concentration is not 200 ppm or more (S9: NO), the CPU 40 determines whether the increase degree of the CO concentration is equal to or higher than a predetermined increase degree at 100 ppm or more and less than 200 ppm (S10).

  If it is determined that the degree of increase is not equal to or greater than the predetermined increase degree (S10: NO), the process proceeds to step S1. When it is determined that the degree of increase is equal to or greater than the predetermined increase degree (S10: YES), the CPU 40 determines that the fire is in another room and causes the sound alarm unit 50 to output the first fire alarm (S11). At this time, the voice alarm unit 50 outputs “There may be a fire in the room or in the adjacent room. Check the room and the source of the fire immediately.” Thereafter, the process shown in FIG. 7 ends.

  When it is determined that the CO concentration is 200 ppm or more (S9: YES), the CPU 40 determines whether or not the detected CO concentration is 500 ppm or more (S12). When it is determined that the CO concentration is not 500 ppm or more (S12: NO), the CPU 40 determines whether the increase degree of the CO concentration is equal to or higher than a predetermined increase degree at 200 ppm or more and less than 500 ppm (S13).

  If it is determined that the degree of increase is not equal to or greater than the predetermined increase degree (S13: NO), the process proceeds to step S1. When it is determined that the degree of increase is equal to or greater than the predetermined degree of increase (S13: YES), the CPU 40 determines that the fire is in another room and causes the voice alarm unit 50 to output a second fire alarm (S11). At this time, the voice alarm unit 50 outputs “There may be a fire in the room or in the adjacent room. Please evacuate immediately.” Thereafter, the process shown in FIG. 7 ends.

  When it is determined that the CO concentration is 500 ppm or more (S12: YES), the CPU 40 determines whether or not the detected CO concentration is 1000 ppm or more (S15). When it is determined that the CO concentration is not 1000 ppm or more (S12: NO), the CPU 40 outputs a third fire alarm from the voice alarm unit 50 (S16). At this time, the voice alarm unit 50 outputs “There may be a fire in the room or in the adjacent room. Please evacuate immediately.” Thereafter, the process shown in FIG. 7 ends.

  When it is determined that the CO concentration is 1000 ppm or more (S15: YES), the CPU 40 outputs a fourth fire alarm from the voice alarm unit 50 (S17). At this time, the voice alarm unit 50 outputs “fire. Please evacuate immediately”. Thereafter, the process shown in FIG. 7 ends.

  FIG. 8 is a flowchart showing a fire determination method of the fire alarm device 1 according to the present embodiment, and shows a second method. As shown in FIG. 8, first, the CPU 40 detects the CO concentration based on the signal from the CO sensor 10 (S21). Next, the CPU 40 determines whether or not the detected CO concentration is 20 ppm (specific value) or more (S22). In the present embodiment, the specific value is 20 ppm. However, the specific value is not limited thereto, and the specific value may be other values including 0 ppm.

  When it is determined that the CO concentration is 20 ppm or more (S22: YES), the CPU 40 starts a timer (S23). Then, the CPU 40 obtains an arrival time T until, for example, the COHb concentration reaches 10% from the CO concentration detected in step S21, and integrates this reciprocal by the equation Σ (1 / T) (S24).

  Next, the CPU 40 determines whether or not the integrated value Σ (1 / T) is 1 or more (S25). When it is determined that the integrated value Σ (1 / T) is not 1 or more (S25: NO), the process proceeds to step S21. On the other hand, when it is determined that the integrated value Σ (1 / T) is 1 or more (S25: NO), the CPU 40 determines that a fire has occurred (S26).

Then, after starting the timer in step S23, the CPU 40 determines whether or not the duration until the fire is determined in step S26 is less than the specified time (S27). When it is determined that the duration is not less than the specified time (S27: NO ), the CPU 40 determines that a smoldering fire has occurred (S28). Then, the CPU 40 outputs a smoldering fire alarm from the voice alarm unit 50 (S29). At this time, the sound alarm unit 50 may output the same sound as the first to second smoldering fire alarms, or may output other sounds. Thereafter, the process shown in FIG. 8 ends.

On the other hand, when it is determined that the duration time is less than the specified time (S27: YES ), the processing shown in FIG. 8 ends.

  By the way, when it is determined that the CO concentration is not 20 ppm or more (S22: NO), the CPU 40 determines whether or not this state has continued for, for example, a specific time (for example, 1 hour) (S30). When it is determined that it has not continued for a specific time (S30: NO), the process proceeds to step S21.

  On the other hand, when determining that it has continued for a specific time (S30: YES), the CPU 40 resets the integrated value Σ (1 / T) obtained in step S24 and the timer started in step S23 (S31). Thereafter, the process proceeds to step S21.

  In this way, it is determined that a smoldering fire has occurred when the duration until the COHb concentration reaches a predetermined value is longer than the specified time. Here, the present inventors have found a tendency for CO to gradually increase in the low concentration region in the early and middle stages of the smoldering fire. For this reason, the duration until the COHb concentration reaches a predetermined value at the occurrence of a smoldering fire is longer than the specified time due to the gradual increase of CO in the low concentration region. Therefore, it is possible to determine a smoldering fire based on the signal from the CO sensor.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. For example, in the above embodiment, each value is not limited to the above value, and can be changed as appropriate.

  The predetermined concentration range may be set to a range exceeding 100 ppm. Furthermore, the predetermined density range may have only a lower limit value and may be set so that the upper limit value is infinite. Furthermore, the predetermined time may be a fixed value or a variable value.

  In the above embodiment, the reciprocal of the arrival time based on the CO concentration has been described in units of minutes. However, the integration is not limited to units of minutes, and may be performed in units of several seconds. Integration may be performed in units of seconds.

  In addition, in the above embodiment, the fire is determined based on the COHb concentration of 10%. However, the present invention is not limited to this, and may be determined based on 20%, 30%, or the like. The alarm content may be changed.

DESCRIPTION OF SYMBOLS 1 ... Fire alarm 10 ... CO sensor 20 ... Thermal sensor 30 ... Smoke sensor 40 ... CPU (determination part)
50 ... Voice alarm (fire alarm)

Claims (2)

A CO sensor that outputs a signal according to the surrounding carbon monoxide concentration;
A determination unit for determining a fire based on a signal from the CO sensor;
A fire alarm unit that issues a fire alarm when a fire is determined by the determination unit;
Storage means for storing data on arrival time until blood carbon monoxide hemoglobin concentration corresponding to various carbon monoxide concentrations reaches a predetermined value, and
Based on the signal from the CO sensor and the storage content of the storage means , the determination unit determines whether the blood carbon monoxide hemoglobin after the carbon monoxide concentration based on the signal from the CO sensor becomes equal to or greater than a specific value. fire alarm, characterized in that it is determined that the concentration is Ibushisho fire if the duration until it is determined that reached the predetermined value becomes the prescribed time or more has occurred. A determination step of determining a fire based on a signal from a CO sensor that outputs a signal corresponding to the surrounding carbon monoxide concentration;
A fire alarm step for issuing a fire alarm when a fire is determined in the determination step,
In the determination step, based on the signal from the CO sensor and the storage contents of the storage means storing the data of the arrival time until the blood carbon monoxide hemoglobin concentration corresponding to various carbon monoxide concentrations reaches a predetermined value. Te, the CO concentration of carbon monoxide from a specific value or more based on the signal from the sensor, if the carbon monoxide hemoglobin concentration in blood duration until it is determined that reached the predetermined value becomes the prescribed time or more A fire alarm fire detection method, characterized in that it is determined that a fire broke out.