JP2006309514A - Fire alarm and arithmetic method for exchange period of smoke sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fire alarm for clarifying the exchange period of a smoke sensor, and for reducing maintenance costs or labors, and the arithmetic method of the exchange period of the smoke sensor. <P>SOLUTION: The fire alarm X is provided with a scattered light type smoke sensor S having a smoke sensing function, an alarm means 10 for emitting alarm when smoke with a predetermined value or more is detected by the scattered light type smoke sensor S, an exchangeable power source part 20 for supplying a driving power to the scattered light type sensor S, a sensitivity checking means 30 for checking the sensor sensitivity of the scattered light type smoke sensor S when any smoke does not exist, a sensitivity history storing means 40 for storing the sensor sensitivity acquired by the sensitivity checking means 30 and a means 50 for performing the arithmetic operation of the exchange period of the scattered light type smoke sensor S based on the sensor sensitivity stored in the sensitivity history storing means 40. This method for performing the arithmetic operation of the exchange period of the scattered light type smoke sensor S is executed when exchanging the power source part 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a smoke sensor having a smoke detection function, alarm means for issuing an alarm when the smoke sensor detects smoke of a predetermined value or more, a power supply unit that supplies drive power to the smoke sensor and is replaceable And a method for calculating the replacement time of the smoke sensor.

The fire alarm is configured to detect an occurrence of smoke due to, for example, an indoor fire using a smoke sensor and issue an alarm. By issuing an alarm in this way, it is possible to extinguish the initial fire and minimize damage.
This fire alarm requires a power source for driving the smoke sensor. The power source includes an external power source type and a battery type.
External power fire alarms may require power supply work such as cable wiring and outlet installation. In this case, in addition to installing the fire alarm itself, the power supply work cost and labor may be spent. Become. Therefore, from the viewpoint of promoting the spread of fire alarms, battery-type fire alarms that can be easily installed are preferred.

  In addition, the sensor sensitivity of the smoke sensor changes over time due to dirt on the sensor element surface, deterioration of the sensor element, and the like. For this reason, it is necessary to perform periodic sensor sensitivity check work in a situation where no smoke is present, and to check whether the smoke sensor is operating normally. Thereby, it becomes a fire alarm which can detect a fire reliably using a smoke sensor with a normal sensor sensitivity.

  In addition, since the said fire alarm has a general apparatus structure, a patent document is not shown.

In the above-described battery-type fire alarm device, it is desired to reduce the size of the fire alarm device so that the installation location is selected as little as possible. Therefore, it is necessary to limit the number of batteries that can be used as much as possible. In this case, it is necessary to replace the battery in order to continuously use the fire alarm for a long time.
In addition, the smoke sensor periodically performs a sensitivity check operation. When the smoke sensor does not maintain a certain sensor sensitivity, it is determined that the sensor life has expired, and the smoke sensor is replaced.
Here, in the battery-type fire alarm device, the smoke sensor and the battery are normally replaced by a trader.

In general, battery life and smoke sensor life do not match. For example, when a supplier replaces a battery, the smoke sensor may be checked for sensitivity at the same time. If it is determined that the sensor sensitivity is normal as a result of the inspection, there are cases where the sensor life is reached until the next battery replacement and cases where the sensor life is exhausted until the next battery replacement. That is, the replacement time of the smoke sensor is unknown during the sensor sensitivity check work.
In the latter case, when the sensor lifetime is exhausted, the smoke sensor is replaced by notifying the sensor sensitivity abnormality. At this time, the smoke sensor replacement and the battery replacement are performed at different timings. Therefore, since these replacement operations are separately generated, there is a problem that maintenance costs and labor are consumed each time.

  Accordingly, an object of the present invention is to provide a fire alarm and a smoke sensor replacement time calculation method that can clarify the replacement time of the smoke sensor and reduce maintenance costs and labor.

  In order to achieve the above object, a fire alarm according to the present invention includes a smoke sensor having a smoke detection function, alarm means for issuing an alarm when the smoke sensor detects smoke of a predetermined value or more, and the smoke sensor. A fire alarm provided with a replaceable power supply unit for supplying driving power, the characteristic configuration of which is a sensitivity check means for checking the sensor sensitivity of the smoke sensor when no smoke is present, and the sensitivity check Sensitivity history storage means for storing the sensor sensitivity obtained by the means, and replacement time calculation means for calculating the replacement time of the smoke sensor based on the sensor sensitivity stored in the sensitivity history storage means. .

  According to said 1st characteristic structure, since it has the sensitivity history memory | storage means which memorize | stores the sensor sensitivity obtained by the sensitivity inspection means, the sensor sensitivity immediately after installation of a smoke sensor and the sensor sensitivity inspection obtained by the sensitivity inspection means Sensor sensitivity history such as sensor sensitivity at the time can always be held in the sensitivity history storage means. Therefore, the sensor sensitivity before the battery replacement after the battery replacement, for example, the sensor sensitivity immediately after the installation of the smoke sensor is not cleared, and the sensor sensitivity history before the battery replacement is maintained even after the battery replacement. Accordingly, for example, the sensor sensitivity immediately after the installation of the smoke sensor is compared with the current sensor sensitivity, and the replacement time of the smoke sensor can be accurately calculated by the replacement time calculation means.

  Therefore, with the fire alarm device of the present invention, it becomes possible to clearly determine the replacement time of the smoke sensor, and the replacement work of the smoke sensor can be performed systematically, so that maintenance costs and labor can be reduced.

  In order to achieve the above object, the first characteristic configuration of the smoke sensor replacement timing calculation method according to the present invention is that the calculation of the smoke sensor replacement timing in the fire alarm is performed when the power supply unit is replaced. is there.

In order to continue using the battery-type fire alarm for a long time, it is necessary to replace the battery. Therefore, replacement of the battery serving as the power supply unit is a maintenance work for the fire alarm that is required periodically.
Therefore, if the calculation of the replacement time of the smoke sensor is also performed at the time of battery replacement work, the lifetime of the smoke sensor can be predicted at the time of battery replacement, and the replacement time of the smoke sensor can be clarified. At this time, if it is found that the smoke sensor replacement time is before, for example, the next battery replacement time, the smoke sensor can also be replaced when the current battery is replaced.
Therefore, according to the smoke sensor replacement time calculation method of the present invention, it is possible to save the trouble of having to go to the site where the fire alarm is installed in order to perform only the calculation of the smoke sensor replacement time. Therefore, it is possible to reduce separate maintenance costs and labor that have occurred because the smoke sensor replacement and the battery replacement are performed at different timings.

  The second characteristic configuration of the smoke sensor replacement time calculation method according to the present invention calculates a sensitivity change constant based on a change in sensor sensitivity stored in the sensitivity history storage means, and uses the sensitivity change constant to determine a predetermined value. By calculating the sensor sensitivity of the smoke sensor when no smoke is present after the period, and determining whether the sensor sensitivity is within a predetermined sensitivity range that is normal sensor sensitivity, the calculation of the replacement time of the smoke sensor is performed. There is in point to do.

  In this configuration, a sensitivity change constant is calculated based on a change in sensor sensitivity stored in the sensitivity history storage unit. For example, when the sensor sensitivity immediately after installation of the smoke sensor and the sensor sensitivity at the time of battery replacement are stored in the sensitivity history storage means, the change in sensor sensitivity is calculated as a slope by graphing these sensor sensitivities. That is, this slope can be used as a sensitivity change constant.

  Then, using this sensitivity change constant, the sensor sensitivity of the smoke sensor when there is no smoke after a predetermined period (for example, at the next battery replacement) is calculated. That is, a predicted value of sensor sensitivity at a certain time in the future is calculated using the sensitivity change constant.

  At this time, if the predicted sensor sensitivity at the next battery replacement is outside the allowable range for normal sensor sensitivity, even if the current sensor sensitivity is within the allowable range for normal sensor sensitivity, Judge as abnormal. That is, it is determined that the smoke sensor does not have a long life, and the smoke sensor is replaced when the current battery is replaced.

As a result, it is possible to predict by a prior calculation that the sensor sensitivity will be abnormal at a certain time in the future, so that the smoke sensor can be replaced when this prediction is made.
Therefore, with this configuration, the sensitivity change constant can be calculated based on the sensor sensitivity stored in the sensitivity history storage means, and the smoke sensor replacement time can be calculated using this sensitivity change constant. The life of the smoke sensor can be predicted by a simple method. Furthermore, the fire alarm is not used when the sensor sensitivity of the smoke sensor is abnormal, and a reliable fire alarm can be performed.

  The third characteristic configuration of the smoke sensor replacement timing calculation method according to the present invention is to calculate a plurality of sensitivity change constants before the power supply unit is replaced, and to calculate a composite sensitivity change constant based on these constants. The sensor sensitivity of the smoke sensor when no smoke is present after a predetermined period is calculated using the composite sensitivity change constant, and it is determined whether the sensor sensitivity falls within a predetermined sensitivity range that is a normal sensor sensitivity. Thus, the replacement time of the smoke sensor is calculated.

In this configuration, it is assumed that the rate of change in sensor sensitivity changes from the middle of installation of the smoke sensor.
That is, this configuration calculates a plurality of sensitivity change constants before the power supply unit is replaced. For example, if the sensor sensitivity immediately after installation of the smoke sensor, the sensor sensitivity after a certain period of time, and the sensor sensitivity at the time of battery replacement are stored in the sensitivity history storage means, these two sensor sensitivities can be graphed. The slope (sensitivity change constant) can be calculated.
Here, since the sensor sensitivity of the smoke sensor has changed from the middle of installation, these two constants have different values. That is, a composite sensitivity change constant that is predicted to be a slope between the present time and after a predetermined period is calculated using the change ratios existing in these two constants.
Then, the sensor sensitivity of the smoke sensor when there is no smoke at the next battery replacement, for example, is calculated after a predetermined period using this composite sensitivity change constant. That is, a predicted value of sensor sensitivity at a certain time in the future is calculated using the composite sensitivity change constant.

  Therefore, with this configuration, the smoke sensor replacement time can be calculated using a composite sensitivity change constant calculated based on a plurality of parameters (sensitivity change constants), so the sensitivity change of the smoke sensor can be captured more reliably. Therefore, a reliable replacement time can be predicted by calculation.

Embodiments of the present invention will be described below with reference to the drawings.
The fire alarm is configured to generate an alarm by detecting, for example, smoke or gas generated due to an indoor fire or the like using a sensor. As this sensor, a smoke sensor that detects smoke, a known gas sensor that detects CO gas generated in the event of a fire, or the like can be applied. In this embodiment, a fire alarm using a smoke sensor will be described.
If this fire alarm is indoors, for example, it is arranged in a wall-mounted or ceiling-mounted manner.

As shown in FIG. 1, the fire alarm device X includes a smoke sensor S having a smoke detection function, an alarm unit 10 that issues an alarm when the smoke sensor S detects smoke exceeding a predetermined value, and the smoke sensor S. A power supply unit 20 that supplies drive power and is replaceable is provided.
The fire alarm device X of the present invention includes a sensitivity checking means 30 for checking the sensor sensitivity of the smoke sensor S when no smoke is present, and a sensitivity history storage means 40 for storing the sensor sensitivity obtained by the sensitivity checking means 30. And a replacement time calculating means 50 for calculating the replacement time of the smoke sensor S based on the sensor sensitivity stored in the sensitivity history storage means 40.

  As the smoke sensor S, for example, a scattered light type smoke sensor S having a smoke sensing function can be applied. The scattered light type smoke sensor S includes a light emitting unit S1 and a light receiving unit S2, and uses a scattering phenomenon that occurs when light from the light emitting unit S1 strikes smoke particles, and is generated when the light receiving element of the light receiving unit S2 receives scattered light. A change in the photocurrent is converted into a smoke density.

  The alarm means 10 is configured by a microcomputer or the like that is controlled to output a warning signal by determining that the smoke is due to fire when the scattered light smoke sensor S detects smoke of a predetermined value or more. The alarm unit 10 is connected to a notification unit 11 such as a speaker / alarm lamp. That is, when a warning signal is output from the warning means 10 to the notification means 11, the generation of smoke due to fire can be notified visually by an alarm sound or visually by flashing of a lamp or the like.

  The power supply unit 20 accommodates a replaceable battery and supplies driving power to the scattered light smoke sensor S. As the battery, a known battery such as an alkaline battery or a lithium battery can be applied. The power supply unit 20 not only supplies driving power only to the scattered light smoke sensor S, but also supplies power to all members of the fire alarm X that require driving power. Constitute.

The sensitivity checking means 30 is configured to check the sensor sensitivity of the scattered light smoke sensor S. For example, the sensor output of the scattered light smoke sensor S is measured in a normal atmosphere where smoke does not exist at a certain timing. With a certain timing, various timings, such as immediately after installing the unused scattered light type smoke sensor S in the fire alarm device X, at the time of battery replacement, or a set predetermined interval, can be set. In order to check the sensitivity at predetermined intervals, a real-time clock having a clock function can be provided in the fire alarm device X.
Then, the sensor sensitivity of the scattered light type smoke sensor S is checked by inputting an inspection switch (not shown) automatically at a desired timing or manually by an operator.

  The sensitivity history storage means 40 stores the sensor sensitivity obtained by the sensitivity check means 30, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory), a memory that does not erase the stored data even if the flash memory is turned off, etc. However, the present invention is not limited to these, and any known memory can be used.

The replacement time calculation means 50 is configured by a microcomputer or the like that calculates the replacement time of the scattered light type smoke sensor S based on the sensor sensitivity data stored in the sensitivity history storage means 40. The calculation of the replacement time of the scattered light type smoke sensor S will be described later.
The replacement time calculation means 50 is connected to sensor abnormality notification means 51 such as a speaker / alarm lamp. That is, when the scattered light type smoke sensor S is determined to be abnormal in sensitivity by the replacement time calculation means 50, a sensor abnormality signal is output to the sensor abnormality notification means 51 and aurally or by flashing the lamp. Thus, it is possible to visually notify the sensor sensitivity abnormality.

  According to the fire alarm device X of the present invention, since the sensitivity history storage means 40 for storing the sensor sensitivity obtained by the sensitivity inspection means 30 is provided, the sensor sensitivity immediately after the installation of the scattered light smoke sensor S and the sensitivity inspection are provided. The sensor sensitivity history such as the sensor sensitivity at the time of the sensor sensitivity check obtained by the means 30 can always be held in the sensitivity history storage means 40. Therefore, after the battery replacement, the sensor sensitivity before the battery replacement, for example, the sensor sensitivity immediately after the installation of the scattered light smoke sensor S is not cleared, and the sensor sensitivity history before the battery replacement is maintained even after the battery replacement. . Thereby, for example, the sensor sensitivity immediately after the installation of the scattered light type smoke sensor S is compared with the current sensor sensitivity, and the replacement time calculating means 50 can accurately calculate the replacement time of the scattered light type smoke sensor S.

  Therefore, with the fire alarm device X of the present invention, it becomes possible to clearly determine the replacement time of the scattered light type smoke sensor S, and the replacement work of the smoke sensor can be performed in a planned manner, so that maintenance costs and labor can be reduced. .

  Below, the calculation method of the alarm level of the fire alarm device X of this invention and the replacement time of the scattered light type smoke sensor S is explained in full detail.

<Alarm level setting method with sensor sensitivity change in fire alarm>
As described above, the scattered light type smoke sensor S uses the scattering phenomenon that occurs when the light from the light emitting unit S1 hits the smoke particles, and changes the photocurrent that occurs when the light receiving element of the light receiving unit S2 receives the scattered light. It is configured to convert to a concentration.

On the other hand, since the light from the light emitting part S1 is scattered even in an atmosphere where no smoke exists, the output voltage value of the scattered light type smoke sensor S in the initial state is not zero (FIG. 2, Na). Therefore, the relationship between the smoke density and the output voltage value of the light receiving unit S2 is expressed by a function A. This is a function of the initial characteristics in which the sensitivity degradation of the scattered light smoke sensor S does not occur.
Here, the sensor sensitivity of the scattered light type smoke sensor S changes over time due to dirt on the surface of the sensor element, deterioration of the sensor element, and the like. The sensitivity change of the scattered light type smoke sensor S includes high sensitivity and low sensitivity.

The increase in sensitivity is caused by an increase in the amount of light received by the light receiving unit S2 due to an increase in light scattering due to dirt or the like of the scattered light type smoke sensor S, resulting in an increase in signal value.
This change is represented by a function B that is translated with respect to the function A of the initial characteristic.

On the other hand, the reduction in sensitivity occurs when the light emission amount or the light reception amount decreases due to the deterioration of the light emitting element of the light emitting unit S1 or the light receiving element of the light receiving unit S2.
This change is represented by a function C obtained by reducing the slope of the function A of the initial characteristics.

  Considering the sensitivity change of the scattered light smoke sensor S, it is necessary to define a range of sensor sensitivity that can be determined to be normal in the scattered light smoke sensor S. This is defined by the range in which the base voltage value fluctuates due to sensitivity change in the absence of smoke (smoke density 0 (% / m)), for example, the output voltage value (base voltage value) at the time of inspection. That is, when the upper limit value and the lower limit value are set in the base voltage value, and the base voltage value at the time of actual inspection deviates from the level of these upper and lower limit values, the scattered light type smoke sensor S is abnormal in sensitivity. Judge.

Here, the relationship between the output voltage value, the upper limit value, and the lower limit value during actual inspection will be described in detail with reference to FIG.
In the event of a fire, the scattered light type smoke sensor S is set so as to determine that smoke having a specific smoke density Xa or more has been detected based on an output voltage value of a specific alarm level Ya or higher. Here, in consideration of the sensitivity change of the scattered light type smoke sensor S, it is desirable to give a certain range to the specific smoke density Xa and to determine that it is a fire when the smoke density within the range is detected. . This smoke density range is the alarm range. As a result, a reliable fire alarm can be issued.

That is, as shown in FIG. 2, when the sensitivity characteristic of the normal scattered light type smoke sensor S is expressed by the function A, the smoke density Xa is the alarm level Ya. At this time, the base in the scattered light type smoke sensor S is concerned. The voltage value is Na.
On the other hand, when the scattered light type smoke sensor S becomes highly sensitive (function B), the alarm level Ya becomes the smoke density Xb. Further, when the sensitivity of the scattered light smoke sensor S is lowered (function C), the alarm level Ya becomes the smoke concentration Xc. That is, considering the sensitivity change of the scattered light type smoke sensor S, the alarm range is smoke concentrations Xb to Xc, and the relationship of each smoke concentration in the alarm range is Xb <Xa <Xc.

  Here, when the sensitivity of the scattered light smoke sensor S increases, even if the sensitivity of the scattered light smoke sensor S is increased, an alarm is not issued until the smoke concentration reaches Xb. The characteristic of the scattered light smoke sensor S with high sensitivity is represented by a function B having the same slope as the function A of the initial characteristic. In this function B, the base voltage value is Nb, and this base voltage value is the upper limit value Nb.

  On the other hand, when the sensitivity of the scattered light type smoke sensor S is lowered, even if the scattered light type smoke sensor S has a reduced sensitivity, an alarm is issued if the smoke concentration increases to Xc. The characteristic of the scattered light type smoke sensor S having a reduced sensitivity is represented by a function C in which the slope is reduced with respect to the function A of the initial characteristic. In this function C, the base voltage value is Nc, and this base voltage value is the lower limit value Nc. In the functions A and C, the zero point M of the output voltage value is common.

  Therefore, the above-described change in the characteristics of the alarm range can be determined based on the output voltage value in the absence of smoke. Such a relationship between the base voltage values is Nc <Na <Nb.

As described above, in the function A of the initial characteristics of the scattered light type smoke sensor S, the smoke density Xb which is the alarm level Ya when the sensitivity is increased and decreased with the smoke density Xa (for example, 10% / m) as a reference. And functions B and C of the scattered light type smoke sensor S whose characteristics are changed assuming Xc (for example, 5% / m and 15% / m), respectively. Then, in the base voltage value, upper and lower limit values Xb and Xc that define the normal sensor sensitivity of the scattered light type smoke sensor S are set. That is, when the base voltage value at the time of actual inspection deviates from the upper and lower limit levels, it is determined that the scattered light smoke sensor S is abnormal in sensitivity.
As a result, even if the sensitivity of the scattered light smoke sensor S is changing, an allowable range of the base voltage value can be provided, so that frequent false alarms due to high sensitivity and delays due to low sensitivity can be avoided. It is possible to prevent the occurrence and provide a reliable fire alarm.

<Calculation method for replacement time of scattered light smoke sensor>
In order to check whether or not the scattered light type smoke sensor S can be continuously installed at the time of battery replacement based on the upper limit value Nb and the lower limit value Nc set as described above, the replacement time of the scattered light type smoke sensor S is examined. The method of calculating is shown below. Although the sensitivity reduction of the scattered light type smoke sensor S is exemplified as the sensitivity reduction, the replacement time can be calculated by the same method for the sensitivity enhancement.

(Calculation method 1)
In this method, a sensitivity change constant is calculated based on a change in sensor sensitivity stored in the sensitivity history storage means 40, and the scattered light type smoke sensor when no smoke is present after a predetermined period is calculated using the sensitivity change constant. The sensor sensitivity of S is calculated, and it is determined whether the sensor sensitivity falls within a predetermined sensitivity range that is the normal sensor sensitivity, thereby calculating the replacement time of the scattered light type smoke sensor S.

As shown in FIG. 3, the output voltage value (sensor sensitivity) of the scattered light smoke sensor S in the initial state is N (0), and the output voltage value of the scattered light smoke sensor S at the time of battery replacement is N (x ), And the sensitivity of the output voltage value N (x) at the time of replacement is lower than that of the initial state output voltage value N (0). These output voltage values are stored in the sensitivity history storage means 40 automatically or by manual operation input by an operator.
At this time, an inclination G (sensitivity change constant) indicating a change in sensitivity reduction of the scattered light type smoke sensor S is obtained. Then, in order to check whether the output voltage value of the sensor S becomes abnormal in sensitivity until the next battery replacement, that is, whether the output voltage value is lower than the lower limit value Nc, based on the slope G, The predicted output voltage value N (y) of the scattered light type smoke sensor S is calculated.
As shown in FIG. 3, the gradient G ′ between the output voltage value N (x) at the time of replacement and the predicted output voltage value N (y) is set similarly to the gradient G, and the predicted output voltage value N (y). When derived, the predicted output voltage value N (y) exceeds the lower limit value Nc. For this reason, the scattered light type smoke sensor S does not become abnormal in sensitivity even at the next battery replacement. That is, it is recognized that the sensor has a long life. Therefore, the installation of the scattered light type smoke sensor S can be continued.

On the other hand, a case where the output voltage value at the time of replacement of the scattered light type smoke sensor S at the time of battery replacement is N (x1) is shown below. At this time, based on the gradient G1 indicating the change in the sensitivity of the scattered light smoke sensor S, the gradient G1 ′ between the replacement output voltage value N (x1) and the predicted output voltage value N (y1) is defined as the gradient G1. Similarly, the predicted output voltage value N (y1) is derived. When the calculated predicted output voltage value N (y1) of the scattered light type smoke sensor S falls below the lower limit value Nc, the scattered light type smoke sensor S becomes abnormal in sensitivity at the next battery replacement. That is, it is recognized that the sensor S does not have a long life. Therefore, the sensor S is replaced at the time of battery replacement this time.
As a result, it is possible to predict that the sensor sensitivity will be abnormal at a certain time in the future (at the time of next battery replacement in FIG. 3) by a prior calculation. Therefore, when this prediction is made, the smoke sensor is replaced. it can.
In addition, it is good to comprise so that the sensor sensitivity memorize | stored in the sensitivity log | history memory | storage means 40 may be cleared when a smoke sensor is replaced by providing a reset switch.

  If the output voltage value N (x) at the time of replacement is already lower than the lower limit value Nc, it is determined that the life of the scattered light smoke sensor S has expired, and the sensor S is replaced at the time of battery replacement this time.

(Calculation method 2)
In this method, before the power supply unit 20 is replaced, a plurality of sensitivity change constants are calculated, a composite sensitivity change constant is calculated based on these constants, and the composite sensitivity change constant is used for a predetermined period of time. The sensor sensitivity of the scattered light smoke sensor S when no smoke is present is calculated, and it is determined whether the sensor sensitivity falls within a predetermined sensitivity range that is a normal sensor sensitivity. Calculate the time.
In this method, it is assumed that the sensor sensitivity change rate changes from the middle of the installation of the scattered light smoke sensor S.

  In the calculation method 1 described above, an inspection opportunity is set automatically or manually before battery replacement, and the output voltage value of the scattered light smoke sensor S at this time is set to N (z) (FIG. 4). And the output voltage value of the said scattered light type smoke sensor S at the time of battery replacement is set to N (x1). These output voltage values are stored in the sensitivity history storage unit 40 in the same manner as the calculation method 1. The inspection opportunity may be performed at regular time intervals or irregularly, and the number of inspections may be set once or more.

  In each case, a slope (sensitivity change constant) indicating a change in sensitivity reduction is calculated. That is, the gradient G2, which is a sensitivity change constant from the initial state output voltage value N (0) to the inspection output voltage value N (z), the inspection output voltage value N (z) to the replacement output voltage value N (x1). A slope G3 that is a sensitivity change constant up to is calculated. In this way, a plurality of sensitivity change constants are calculated before battery replacement.

  In such a case, when examining whether or not the sensor S is abnormal in sensitivity until the next battery replacement, the sensitivity decrease gradients G2 and G3 are used. Here, since the sensor sensitivity of the scattered light smoke sensor S changes from the middle of installation, these two constants have different values. That is, based on the change rate existing in these two constants, an estimated gradient G4 (composite sensitivity change constant) from the present time to the next battery replacement is calculated, and the scattered light type smoke sensor S is predicted at the next battery replacement. An output voltage value N (y2) is calculated.

  As shown in FIG. 4, since the inclination G3 is gentler than the inclination G2, the ratio of the sensitivity reduction of the scattered light smoke sensor S is reduced. This is because, for example, after the scattered light type smoke sensor S is desensitized by the time of inspection and the slope of the decrease in sensitivity becomes G2, the sensor S becomes highly sensitive due to dirt of the scattered light type smoke sensor S, etc. As a result, there may be a case where the lowering of the sensitivity and the increasing of the sensitivity proceed at the same time and the slope of the sensitivity decrease becomes G3.

  As shown in FIG. 4, since the predicted output voltage value N (y2) exceeds the lower limit value Nc, the scattered light smoke sensor S does not become abnormal in sensitivity even at the next battery replacement. That is, it is recognized that the sensor has a long life. Therefore, the installation of the scattered light type smoke sensor S can be continued.

  In this way, by setting inspection opportunities other than at the time of battery replacement and calculating multiple slopes of sensitivity reduction, the smoke sensor uses a composite sensitivity change constant calculated based on multiple parameters (sensitivity change constants). Therefore, the change in sensitivity of the scattered light type smoke sensor S can be captured more reliably, so that the accurate replacement time can be predicted by calculation.

[Another embodiment 1]
As described above, the sensitivity inspection means 30 can set an inspection opportunity other than when the battery is replaced. In this inspection opportunity, it can comprise so that the lifetime of the power supply part 20 may be diagnosed. For example, the battery voltage is measured. When it is determined that the power supply unit 20 needs to be replaced, a power supply unit replacement alarm can be notified.

  The fire alarm of the present invention is used to detect the occurrence of a fire or an abnormal increase in smoke concentration at an early stage. Further, the method for calculating the replacement time of the smoke sensor of the present invention is used to reduce maintenance costs and labor required for replacement of the smoke sensor.

Schematic of the fire alarm of the present invention A diagram outlining how to set the allowable range of the base voltage value based on changes in the characteristics of the normal smoke sensor, the highly sensitive smoke sensor, and the low sensitive smoke sensor Figure outlining the calculation method 1 of the replacement time of the scattered light smoke sensor Figure outlining the calculation method 2 of the replacement time of the scattered light smoke sensor

Explanation of symbols

S Scattered Smoke Sensor X Fire Alarm 10 Alarm Unit 20 Power Supply Unit 30 Sensitivity Check Unit 40 Sensitivity History Storage Unit 50 Replacement Time Calculation Unit

Claims (4)

A fire comprising a smoke sensor having a smoke sensing function, an alarm means for issuing an alarm when the smoke sensor detects smoke of a predetermined value or more, and a power supply unit that supplies drive power to the smoke sensor and can be replaced. In the alarm device,
Sensitivity check means for checking the sensor sensitivity of the smoke sensor when no smoke is present, sensitivity history storage means for storing sensor sensitivity obtained by the sensitivity check means, and sensor sensitivity stored in the sensitivity history storage means A fire alarm device comprising a replacement time calculating means for calculating the replacement time of the smoke sensor based on the above.   A method for calculating the replacement time of the smoke sensor, wherein the calculation of the replacement time of the smoke sensor according to claim 1 is performed when the power supply unit is replaced.   A sensitivity change constant is calculated based on a change in sensor sensitivity stored in the sensitivity history storage means, and the sensor sensitivity of the smoke sensor when no smoke is present after a predetermined period is calculated using the sensitivity change constant. The smoke sensor replacement timing calculation method according to claim 2, wherein the smoke sensor replacement timing is calculated by determining whether the sensor sensitivity falls within a predetermined sensitivity range which is normal sensor sensitivity.   Prior to the replacement of the power supply unit, a plurality of sensitivity change constants are calculated, a composite sensitivity change constant is calculated based on these constants, and smoke is present after a predetermined period using the composite sensitivity change constant. The sensor sensitivity of the smoke sensor when not being calculated is calculated, and the replacement time of the smoke sensor is calculated by determining whether the sensor sensitivity falls within a predetermined sensitivity range that is a normal sensor sensitivity. Method for calculating the replacement time of smoke sensors.

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