JP2019219956A - Fire detector - Google Patents

Abstract

To obtain a fire detector capable of utilizing a detection result of a heat sensor in a smoke detector having the heat sensor and a smoke sensor.SOLUTION: A fire detector includes: a heat sensor; a first smoke sensor; a second smoke sensor; and a control part for stopping operation of the second smoke sensor when the rate of climb of output from the heat sensor is smaller than a threshold, starting the second smoke sensor when the rate of climb of output from the heat sensor is larger than the threshold, and detecting smoke density on the basis of output from the first smoke sensor and the second smoke sensor.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fire detector including a heat sensor and a smoke sensor.

  BACKGROUND ART Conventionally, there is an alarm provided with a heat sensor and a smoke sensor, which are sensors having different fire detection mechanisms, as fire detection sensors (for example, see Patent Document 1).

JP 2000-132761 A

  In the alarm described in Patent Document 1, a fire is determined when the detection result of the heat sensor exceeds the threshold value or when the detection result of the smoke sensor exceeds the threshold value. That is, in the alarm device of Patent Document 1, the heat sensor and the smoke sensor independently detect a fire, and the detection result of the heat sensor and the detection result of the smoke sensor do not affect each other's detection results.

  By the way, a detector provided with a smoke sensor is usually installed on a ceiling or a wall near the ceiling, but the smoke reaches the ceiling or near the ceiling due to an updraft due to heat of a fire. Therefore, when the smoke sensor detects smoke, it can be said that an upward airflow due to heat has occurred. For this reason, the heat sensor of the sensor can detect an increase in heat, although it is not enough to determine that it is a fire based on the detected amount of heat. As described above, the heat sensor and the smoke sensor detect different physical quantities generated by a fire, but the detection result of the heat sensor can be said to indicate the detection result of the smoke sensor. Nevertheless, in the alarm described in Patent Document 1, the detection result of the heat sensor and the detection result of the smoke sensor are handled independently, and the detection result of the heat sensor or the smoke sensor is further processed. It was desired to utilize it.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a smoke detector including a heat sensor and a smoke sensor, which can utilize a detection result of the heat sensor. It is.

  The fire sensor according to the present invention stops operation of the heat sensor, the first smoke sensor, the second smoke sensor, and the second smoke sensor when a rate of increase in output from the heat sensor is smaller than a threshold value. Activating the second smoke sensor when the rate of increase in the output from the heat sensor is greater than a threshold, and detecting the smoke density based on the outputs from the first smoke sensor and the second smoke sensor. And a control unit.

  ADVANTAGE OF THE INVENTION According to this invention, the power consumption of the fire detector provided with two smoke sensors can be reduced using the detection result of a heat sensor.

It is a functional block diagram of a fire detection system and a fire detector according to an embodiment. It is a flowchart explaining the fire detection process of the fire detector which concerns on embodiment. It is a timing chart explaining an example of operation of each part of a fire detector concerning an embodiment.

Embodiment.
(Configuration of fire detector 10)
FIG. 1 is a functional block diagram of a fire detection system and a fire detector 10 according to the embodiment. The fire detector 10 includes a first light emitting element 1, a second light emitting element 2, a light receiving element 3, a control unit 4, a memory 5, an alarm unit 6, and a heat sensor 7. The fire detector 10 is connected to the fire receiver 20 via a signal line, and the fire detector 10 outputs a signal regarding the presence or absence of a fire to the fire receiver 20. In this embodiment, one or more fire detectors 10 and fire receivers 20 constitute a fire detection system.

  The fire detector 10 according to the present embodiment emits light toward a smoke detection space formed in a housing, and receives scattered light generated by smoke existing in the smoke detection space to detect smoke. With a smoke sensor. In the present embodiment, the first light emitting element 1 and the light receiving element 3 function as a first smoke sensor for detecting a change in the physical quantity caused by smoke, and the second light emitting element 2 and the light receiving element 3 detect the physical quantity caused by the smoke. It functions as a second smoke sensor that detects a change. Further, the fire detector 10 of the present embodiment has a heat sensor 7 for detecting heat generated by a fire. As described above, the fire detector 10 according to the present embodiment detects heat and smoke caused by a fire.

  The first light emitting element 1 and the second light emitting element 2 are, for example, LEDs (Light Emitting Diodes) and emit light toward the smoke detection space. The first light emitting element 1 and the second light emitting element 2 both emit red light (for example, a wavelength of 655 nm) in the visible light region toward the smoke detection space. The first light emitting element 1 and the second light emitting element 2 are not limited to those that emit red light having a wavelength of 655 nm, but may be any one that emits light having a peak wavelength within a wavelength range of 600 nm to 700 nm. . The first light emitting element 1 and the second light emitting element 2 include, for example, an amplifier having a variable amplification factor, and light is emitted from the first light emitting element 1 and the second light emitting element 2 at an intensity corresponding to the amplification factor of the amplifier. Is done. Note that the first light emitting element 1 and the second light emitting element 2 may have different wavelengths instead of the same wavelength.

  The light receiving element 3 receives light and outputs a signal corresponding to the intensity of the received light. The light receiving element 3 is, for example, a photodiode. The light receiving element 3 is arranged at a position where light emitted from the first light emitting element 1 and the second light emitting element 2 does not directly enter. That is, if the optical axis of the first light emitting element 1 is the first light emitting axis, the optical axis of the second light emitting element 2 is the second light emitting axis, and the optical axis of the light receiving element 3 is the light receiving axis, the first light emitting axis The light receiving axis intersects, and the second light projecting axis intersects with the light receiving axis. The light receiving element 3 receives scattered light generated by reflecting light emitted from the first light emitting element 1 and the second light emitting element 2 to smoke particles.

  The light receiving element 3 is located at a position where the angle θ1 (scattering angle) of the light receiving axis with respect to the first light projecting axis of the first light emitting element 1 becomes an acute angle (for example, 60 degrees) in a plan view. The angle θ2 (scattering angle) of the light receiving axis with respect to the second light projecting axis is an obtuse angle (for example, 110 degrees). The angle θ1 is different from the angle θ2. Therefore, when the first light emitting element 1 emits light, the light receiving element 3 receives the forward scattered light of smoke generated by the light of the first light emitting element 1. When the second light emitting element 2 emits light, the light receiving element 3 receives the backscattered light of smoke generated by the light of the second light emitting element 2. The angle θ1 may be an acute angle, and is more preferably a value in the range of 50 to 70 degrees. The angle θ2 may be an obtuse angle, and is more preferably a value in the range of 100 degrees to 120 degrees.

  The light receiving element 3 outputs the value of the received light intensity of the scattered light from the smoke generated by the light of the first light emitting element 1 as a first output signal S1, and the scattered light from the smoke generated by the light of the second light emitting element 2 Is output as the second output signal S2.

  The control unit 4 performs control for switching the first light emitting element 1, the second light emitting element 2, the light receiving element 3, and the heat sensor 7 between a start state and a stop state. Here, the activation state refers to a state where power is supplied. Further, the control unit 4 controls the light emitting operation of the first light emitting element 1 and the second light emitting element 2. The control unit 4 also uses the smoke density obtained by A / D converting the first output signal S1 and the second output signal S2 output from the light receiving element 3 with an A / D converter to determine whether a fire has occurred. judge. Data such as a fire threshold used to determine whether a fire has occurred is stored in the memory 5. When determining that a fire has occurred, the control unit 4 controls the alarm unit 6 to transmit a signal indicating the occurrence of the fire to the fire receiver 20.

  Here, the control unit 4 is configured by dedicated hardware or an MPU (Micro Processing Unit) that executes a program stored in a memory. When the control unit 4 is dedicated hardware, the control unit 4 includes, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Applicable. Each of the functions realized by the control unit 4 may be realized by individual hardware, or each function may be realized by one piece of hardware. When the control unit 4 is an MPU, each function executed by the control unit 4 is realized by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in an internal memory. The MPU realizes each function of the control unit 4 by reading and executing a program stored in the internal memory. The internal memory is, for example, a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and an EEPROM. The memory 5 is, for example, a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and an EEPROM. The alarm unit 6 is a signal transmission circuit that transmits a fire signal to the fire receiver 20.

  The heat sensor 7 is a sensor that detects a change in the amount of heat around the fire detector 10. The thermal sensor 7 is, for example, a thermistor, a thermocouple, an infrared sensor, or a Peltier device.

  In the present embodiment, a photoelectric smoke sensor is illustrated as the first smoke sensor and the second smoke sensor, but the specific configuration of the smoke sensor is not limited to this example. An ionization type smoke sensor may be used as the first smoke sensor and the second smoke sensor.

  Next, smoke detection processing for detecting a fire based on smoke and heat detection processing for detecting a fire based on heat will be described.

(Smoke detection processing)
The controller 4 controls the first output signal S1 output from the light receiving element 3 when the first light emitting element 1 emits light, or the smoke density obtained from the first output signal SC1 obtained by correcting the first output signal S1, It is detected whether or not a fire has occurred by comparing with a fire threshold which is a fire determination threshold.

  Here, the process of correcting the first output signal S1 to obtain the first output signal SC1 will be described. When a fire occurs, not only one type of smoke is generated, but also various types of smoke, such as white smoke, gray smoke, and black smoke, depending on the burning matter. In addition, in the room where the fire detector 10 is installed, steam may be generated instead of smoke due to the fire. The fire detector 10 needs to detect and issue a fire when any of these various types of smoke is generated, but it is necessary not to determine that a fire has occurred when steam is generated. The output ratio R (= first output signal S1 / second output signal S2) between the first output signal S1 and the second output signal S2 is a value according to the type of smoke and whether or not steam is present. . That is, from the output ratio R, it is possible to determine the type of smoke and whether or not it is steam.

  The light receiving intensity of the light receiving element 3 when the white smoke and the gray smoke are in the smoke detecting space of the fire detector 10 is larger than the light receiving intensity of the light receiving element 3 when the black smoke is in the smoke detecting space. In other words, when the black smoke is in the smoke detection space, the light receiving intensity of the light receiving element 3 is relatively small. Therefore, if the same fire threshold is used for black smoke, white smoke and gray smoke, it is difficult to determine that a fire has occurred in the case of black smoke. In addition, when steam is present in the smoke detection space, it is necessary to determine that there is no fire. From these, the first output signal S1 is corrected based on the output ratio R, that is, the type of smoke or the like, to obtain a corrected first output signal SC1, and the corrected first output signal SC1 is used. Perform a fire determination.

  The memory 5 stores a correction table or a calculation formula in which the output ratio R, which is an index for determining whether the type of smoke is steam, or not, and the correction coefficient Cf. The control unit 4 acquires the correction coefficient Cf corresponding to the calculated output ratio R with reference to the correction table or the calculation formula, corrects the first output signal S1 using the obtained correction coefficient Cf, and A first output signal SC1 is generated. For example, the corrected first output signal SC1 is obtained as follows: the corrected first output signal SC1 = Cf × the first output signal S1. In order to obtain the corrected first output signal SC1 following the measurement value of the CS meter (dimming meter), the correction coefficient Cf for black smoke is smaller than the correction coefficient Cf for white smoke and gray smoke. Is also a large value. In the case of steam, it is necessary to determine that a fire has not occurred. Therefore, in the case of steam, the corrected output coefficient SC1 of the corrected first output signal SC1 is larger than that of the first output signal S1 before correction. Is set to a value smaller than the value of. Since the corrected first output signal SC1 indicates a value corresponding to the smoke density, the value of the first output signal SC1 is referred to as smoke density.

  The controller 4 determines that a fire has occurred when the corrected value of the first output signal SC1, that is, the smoke density is greater than the fire threshold. If it is determined that a fire has occurred, a fire signal is transmitted from the alarm unit 6 to the fire receiver 20.

  Instead of transmitting the fire signal from the alarm unit 6, the smoke density corresponding to the corrected first output signal SC1 may be transmitted as an analog value. In that case, a fire is determined by the fire receiver 20 that has received the analog value from the alarm unit 6. Although the first output signal S1 has been described as being corrected here, a fire threshold value used for determining a fire may be corrected instead of correcting the first output signal S1.

  The timing at which the control unit 4 acquires the output ratio R will be described. For example, the control unit 4 can periodically and alternately emit the first light emitting element 1 and the second light emitting element 2 to continuously obtain the output ratio R. In addition, the control unit 4 constantly makes the first light emitting element 1 emit light, and monitors whether or not the output from the light receiving element 3 has exceeded a set value set as a value smaller than the fire threshold. This set value is stored in the memory 5. Then, when the output from the light receiving element 3 exceeds the set value, the control unit 4 may cause the first light emitting element 1 and the second light emitting element 2 to emit light alternately to acquire the output ratio R. .

(Heat detection processing)
The control unit 4 detects whether or not a fire has occurred by comparing the amount of heat represented by the signal output from the heat sensor 7 with a heat fire threshold value for determining a fire due to heat.

(Fire detection processing)
Next, the operation of the fire detector 10 according to the present embodiment relating to fire detection will be described. FIG. 2 is a flowchart illustrating a fire detection process of the fire detector 10 according to the embodiment. In the normal monitoring state, the heat sensor 7 and the first smoke sensor are in the activated state, and the second smoke sensor is in the stopped state (S10). In the present embodiment, the first light emitting element 1 and the light receiving element 3 functioning as the first smoke sensor are in the activated state, and the second light emitting element 2 is in the stopped state. No power is supplied to the second light emitting element 2 in the stopped state.

  In the monitoring state, it is determined whether or not the smoke density detected by the first smoke sensor is larger than a fire threshold (S11). Here, the value of the first output signal S1 is used for the determination of the smoke density in step S11. If the smoke density is greater than the fire threshold (S11: YES), the occurrence of a fire is reported (S17). On the other hand, if the smoke density is not higher than the fire threshold (S11: NO), it is determined whether the output of the heat sensor 7 is higher than the heat fire threshold (S12).

  When the output of the heat sensor 7 is larger than the heat fire threshold value (S12: YES), the occurrence of a fire is reported (S17). On the other hand, when the output of the heat sensor 7 is not larger than the heat fire threshold value (S12: NO), the process proceeds to step S13.

  In step S13, it is determined whether or not the rate of increase in the output of the heat sensor 7 is greater than a threshold (S13). The rate of increase in the output of the thermal sensor 7 is determined by the amount of temperature rise per unit time. The threshold can be, for example, 3 ° C./60 seconds. If the rate of increase in the output of the thermal sensor 7 is not greater than the threshold (S13: NO), the process returns to step S10.

  On the other hand, when the rate of increase in the output of the heat sensor 7 is larger than the threshold (S13: YES), the second smoke sensor is activated (S14). In the present embodiment, since the light receiving element 3 functioning as the second smoke sensor has already been activated as the first smoke sensor, the second smoke sensor is switched from the stopped state to the activated state.

  Subsequently, it is determined whether the type of smoke and the steam are steam (S15). The type of smoke is determined based on the output ratio R between the first output signal S1 and the second output signal S2 as described above.

  Subsequently, it is determined whether the smoke density detected by the first smoke sensor is larger than a fire threshold (S16). Here, the value of the corrected first output signal SC1 is used for the determination of the smoke density in step S16. The corrected first output signal SC1 is obtained by correcting the first output signal S1 with a correction coefficient Cf determined according to the type of smoke determined in step S15. If the smoke density is greater than the fire threshold (S16: YES), the occurrence of a fire is reported (S17). On the other hand, if the smoke density is not higher than the fire threshold (S16: NO), the process returns to step S10.

  Thus, in the present embodiment, in the monitoring state, the heat sensor 7 and the first smoke sensor are in the activated state, and the second smoke sensor is in the stopped state.

  FIG. 3 is a timing chart illustrating an operation example of each unit of the fire detector 10 according to the embodiment. FIG. 3 shows a change in the output of the heat sensor 7 and a timing of an operation of accessing the first smoke sensor, the second smoke sensor, the heat sensor 7, and the memory 5. In the example of FIG. 3, the normal monitoring state is maintained until time t. That is, the first smoke sensor and the heat sensor 7 are in the activated state, and the second smoke sensor is in the stopped state (see step S10 in FIG. 2).

  Here, the activated first smoke sensor periodically performs a smoke density detection operation and outputs a first output signal S1 corresponding to the detected value. Specifically, the first light emitting element 1 emits light periodically, and the light receiving element 3 outputs a first output signal S1 corresponding to the light receiving intensity when the first light emitting element 1 emits light. The light receiving element 3 may be started periodically at the timing when the first light emitting element 1 emits light, or may be always started. Further, the thermal sensor 7 in the activated state periodically detects a change in the amount of heat in the surroundings, and outputs a signal corresponding to the detected value.

  While the second smoke sensor is in a stopped state, processing other than fire detection is mainly performed. Specifically, access to the memory 5 by the control unit 4 is performed intermittently. The access to the memory 5 refers to writing data temporarily stored in the internal memory of the control unit 4 to the memory 5 or using data stored in the memory 5 for processing in the control unit 4. Operations such as reading to an internal memory. The data to be read from the memory 5 and the data to be written to the memory 5 include, for example, the operation history of the fire detector 10, the sensitivity compensation value for compensating the sensitivity deviation of the first smoke sensor and the second smoke sensor, and the fire detection. The number of times, the activation time of the fire detector 10, and the like.

  In addition to or instead of accessing the memory 5, the control unit 4 may perform a failure determination process. For example, with the amplification factor of the amplifier provided in the first light emitting element 1 increased for failure determination, the first light emitting element 1 is caused to emit light, and the control unit 4 acquires the output signal of the light receiving element 3 at this time. I do. The control unit 4 can determine whether or not the A / D converter of the control unit 4 has failed, based on whether or not the value of the obtained output signal is within a predetermined range.

  In FIG. 3, the time when the rate of increase in the output of the heat sensor 7, that is, the amount of increase in the output of the heat sensor 7 per unit time, exceeds a threshold is represented by time t. Subsequent to time t, the second smoke sensor is activated. The activated second smoke sensor periodically performs a smoke density detection operation and outputs a second output signal S2 corresponding to the detected value. While the second smoke sensor is in the activated state, access to the memory 5 is not performed. That is, access to the second smoke sensor and the memory 5 is not performed simultaneously.

  As described above, according to the present embodiment, when the rate of increase in the output from heat sensor 7 is smaller than the threshold, the operation of the second smoke sensor is stopped. By stopping the operation of the second smoke sensor, the power consumption of the fire detector 10 can be reduced. In the fire detector 10, the power that can be consumed during monitoring may be determined in advance, but by stopping the second smoke sensor as in the present embodiment, the power consumption may exceed the determined value. Can be prevented.

  Further, according to the present embodiment, the type of smoke is determined based on the output ratio R between the first output signal S1 and the second output signal S2. For this reason, it is possible to accurately determine a fire according to the type of smoke.

  Further, according to the present embodiment, when the rate of increase in the output from heat sensor 7 is smaller than the threshold, the smoke density is detected based on the output of the first smoke sensor. Therefore, the fire monitoring by detecting the smoke density is not interrupted.

  Further, according to the present embodiment, when the rate of increase in the output from the heat sensor 7 is smaller than the threshold, while the operation of the second smoke sensor is stopped, the write processing to the memory 5, the read processing, And at least one of the failure determination processing. Since the operation of the second smoke sensor is stopped, it is possible to suppress the power consumption of the entire fire detector 10 from becoming excessively large even when the writing process to the memory 5 is performed.

  Embodiments of the present invention are not limited to the above embodiments, and various changes can be made to the above embodiments. For example, although it has been described that the control unit 4 of the fire detector 10 performs the fire detection process, the fire receiver 20 may perform the fire detection process. In this case, the fire detector 10 sends the output from the light receiving element 3 to the fire receiver 20 via the transmission line, and the fire receiver 20 corrects the acquired output of the light receiving element 3 and outputs the corrected output. The output is used to determine whether a fire has occurred. Even in this case, the operation and effect described in the above embodiment can be obtained.

  In the above-described embodiment, an example has been described in which the output of the heat sensor 7 that detects heat is used for detecting a fire. That is, in the embodiment, in addition to using the detection result of the heat sensor 7 to detect a fire due to heat, the detection result is also used to stop the operation of the second smoke sensor. However, the output of the heat sensor 7 may not be used for fire detection. In this case, fire detection is performed based on the outputs of the first smoke sensor and the second smoke sensor.

  Further, in the above-described embodiment, an example has been described in which whether to stop the operation of the second smoke sensor is determined based on a comparison result between the rate of increase in the output from the heat sensor 7 and the threshold. Instead of the increase rate of the output from the heat sensor 7, the output from the heat sensor 7 may be used to determine whether to stop the operation of the second smoke sensor. In this case, when the value of the output from the heat sensor 7 is smaller than the threshold value, the operation of the second smoke sensor is stopped. The threshold value to be compared with the output value from the heat sensor 7 is a value smaller than the heat fire threshold value. Even in this case, the power consumption of the fire detector 10 can be reduced by stopping the operation of the second smoke sensor.

  1. 1st light emitting element, 2 second light emitting element, 3 light receiving element, 4 control section, 5 memory, 6 alarm section, 7 heat sensor, 10 fire detector, 20 fire receiver.

Claims (3)

A heat sensor,
A first smoke sensor;
A second smoke sensor;
When the rate of increase in the output from the heat sensor is smaller than a threshold, the operation of the second smoke sensor is stopped, and the smoke density is detected based on the output from the first smoke sensor. A control unit that activates the second smoke sensor when an increase rate of the output is greater than a threshold value and detects smoke density based on outputs from the first smoke sensor and the second smoke sensor. sensor. The control unit includes:
If the output of the heat sensor is higher than a heat fire threshold, it is determined that a fire has occurred,
The fire detector according to claim 1, wherein when the output of the heat sensor is lower than a heat fire threshold, it is determined whether the rate of increase of the output from the heat sensor is higher than the threshold. With memory,
The control unit performs a write process to the memory, a read process from the memory, or a failure determination process when the rate of increase in the output from the thermal sensor is smaller than the threshold. Item 3. The fire detector according to Item 2.

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