JPS641835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects changes in physical phenomena caused by fire, such as smoke and temperature, in an analog manner, calculates the degree of risk of fire by predictive calculation based on this detected data, and calculates the degree of risk of fire by calculating the predicted calculation result. The present invention relates to a fire alarm system that determines fire based on comprehensive judgment.

In conventional fire alarm systems, a fire detector detects a change in a single physical phenomenon such as smoke or heat caused by a fire, and a fire signal is sent to a receiver when the detected value exceeds a set threshold level. The fire alarm is sent out to issue a fire alarm.

However, it seems that the judgment of fire was simply based on whether the threshold level was exceeded or not.
Even when a detected value exceeding the threshold level was obtained due to a cause other than a fire, it was determined to be a fire, and there was no way to distinguish this.

In order to solve the essential problems in conventional fire alarm devices, the inventors of the present application sampled analog detection data such as smoke and temperature that are constantly obtained, and developed a method or function for calculating a difference value from multiple sampling data. We have proposed a device that calculates the current level of danger using predictive calculations using an approximation method and predicts and judges fires (Japanese Patent Application No. 1982-29976, same).
58-119855, etc.). Fire discrimination based on this predictive calculation makes it possible to judge a fire earlier and more accurately than with conventional devices.

However, in the above-mentioned device, depending on the progress of the fire after the predictive calculation of the degree of fire risk has been performed, there is a risk that the predictive calculation may be performed to temporarily determine that there is no danger of fire.

For example, if smoke concentration is detected as a change in the physical phenomenon caused by a fire, as shown in Figure 1, the smoke concentration increases over time as the smoldering fire progresses in the early stages of the fire, and during this period The degree of danger is determined through predictive calculations and a fire signal is sent out. However, when a smoldering fire progresses and ignites, the smoke concentration temporarily decreases due to the rapid generation of hot air currents caused by the ignition, and predictive calculations that capture this decrease in smoke concentration eliminate the risk of fire. There was a problem in that the transmission of fire signals was temporarily cut off even though the fire had actually progressed to ignition.

The present invention has been made in view of these problems, and it is possible to block the transmission of fire signals even if the fire risk is temporarily not determined due to the progress of the fire after the fire risk has been predicted and calculated. It is an object of the present invention to provide a fire alarm device that uses highly reliable predictive calculations and prevents accidents from occurring.

To achieve this objective, the present invention detects changes in physical phenomena caused by fire in an analog manner,
From this detection data, the time required to reach the threshold for determining fire or the reached value after a predetermined period of time is calculated, and if the calculated time is within the set time or the calculated reached value is greater than or equal to the set value, the danger is detected. When the calculation time is less than the set time or the calculated value is less than the set value, an uncertainty signal is sent, and based on this danger signal and uncertainty signal, the danger signal is When a fire signal is obtained, a fire signal is output, and a fire signal is also sent when an uncertain signal is obtained after a dangerous signal is obtained, and even if the uncertain signal disappears, the fire signal is output for a certain period of time. It is designed to make a logical decision to continue outputting.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 2 is a circuit block diagram showing one embodiment of the present invention.

First, to explain the configuration, 1 is a temperature sensor that detects the temperature caused by a fire in an analog manner, 2 is a gas sensor that detects the gas concentration of CO gas generated by the fire, and 3 is a smoke sensor that detects the smoke concentration due to the fire. , temperature detection signal T from temperature sensor 1
However, the gas concentration signal G is output from the gas sensor 2, and the smoke concentration signal S is output from the smoke sensor as analog detection signals.

4 is a difference value calculation determination unit, which includes temperature sensors 1,
The analog detection signals detected by each of the gas sensor 2 and the smoke sensor 3 are sampled at regular intervals, and the difference value is calculated every time, for example, m pieces of sampling data are obtained, and the threshold value for determining a fire is reached. Calculate the time it takes to reach the destination, and use the calculated time to judge whether it is dangerous, uncertain, or safe.

That is, the determination of a fire by predictive calculation based on the detection data in the difference value calculation determination unit 4 is as follows, taking data T detected by the temperature sensor 1 as an example.
This is carried out according to the calculation routine shown in the flowchart of FIG.

First, every time m pieces of temperature data are sampled in block a, an average value Ta is calculated by setting Ta=1/m _o 〓 ⁿ⁼¹ Tn. Next, proceed to block b and calculate the average value Ta-1 obtained in the previous cycle.
Calculate the difference value (Ta−Ta−1) from Next, in block c, by dividing the difference value (Ta - Ta - 1) by the sampling time to (constant value),
Calculate the slope α of temperature change. Next, block d
The time t required for the dangerous temperature to reach the predetermined threshold T _D for determining a fire is calculated as T _D = αt + Ta (1) t = (T _D - Ta)/α (2).

Next, in judgment block e, the dangerous time t1 and block d from the present moment to reach the dangerous temperature threshold T _D are determined.
If the arrival time t is less than the danger time t1, it is determined that there is a fire and a danger signal is output at block f.

On the other hand, in the determination block e, the arrival time t is the critical time.
When it is larger than t1, in the next judgment block g, a threshold value is used to determine whether the time t to reach the dangerous temperature T _D is a safe time that cannot be considered a fire, or an uncertain time that has a high probability of a fire. It compares it with time t2, and if the arrival time t is less than the threshold time t2, it proceeds to block h and outputs an uncertain signal.If the uncertain signal is output at block i, it will be explained later Shifts to the function approximation calculation routine. Further, when the arrival time t exceeds the threshold time t2 in the determination block g, the temperature rise is due to a cause other than a fire, so it is determined that the temperature is safe in the block i.

When the fire judgment based on such a series of difference values is completed, the current average value Ta is calculated in block j.
is replaced with the previous average value Ta-1, and the process returns to block a again.

The calculation process for fire judgment based on the difference value shown in the flowchart of FIG. 3 is as shown in the time chart of FIG. 4, assuming that the calculation time is "0".
Find the slope between the average value Ta-1 of the temperature sampling data at the previous calculation time "-1" and the average value Ta of the current temperature sampling data until the dangerous temperature threshold T _D is reached, which is shown as a physical quantity on the vertical axis. This is a predictive calculation of the arrival time t of
A threshold time t1 for determining danger and uncertainty and a threshold time t2 for determining uncertainty and safety are set. Therefore, for example, if the average value of temperature data at time "0" is Ta1, the time to reach the dangerous temperature threshold T _D will be less than the time threshold t1,
In this case, it is determined to be dangerous and a danger signal is output. In addition, if the average value of temperature data at time “0” is Ta2, the dangerous temperature threshold
The time of arrival at T _D is between the time thresholds t1 and t2, so an uncertainty signal is output. Furthermore, time “0”
If the average value of the temperature data at is Ta3, the time to reach the dangerous temperature threshold T _D is the threshold time
exceeds t2, in which case it is considered safe.

Such arithmetic processing by the difference value calculation discriminator 4 is performed not only on the detection data of the temperature sensor 1, but also on each detection data of the gas sensor 2 and smoke sensor 3, and is performed individually in the same way to determine whether it is safe, uncertain, or dangerous. Either one is determined and a danger signal or uncertainty signal is output.

Again, referring to FIG. 2, the difference value calculation determination unit 4
Subsequently, a function approximation calculation discriminator 5 is provided, and the function approximation operation discriminator 5 selects each function only when an uncertainty signal is output from the difference value operation discriminator 4, as shown in the time chart of FIG. Based on the sensor detection data, a calculation process for determining whether or not there is a fire is performed using a function approximation method.

Next, the fire judgment based on the function approximation method in the function approximation calculation discriminator 5 will be explained in detail using temperature data from the temperature sensor 1 as an example.

Now, if the approximation formula F(t) used for function approximation is F(t)=at ² +bt+c...(3), then the above (3) is calculated based on m detected data.
Temperature changes can be predicted by finding the coefficients a, b, and c in the equation.

Here, if the data function obtained from m pieces of detection data T1, T2,...Tm is f(t), then to obtain the approximate expression F(t) of the above equation (3), {F(t) −f(t)} ² dt (4) It is sufficient to find the coefficients a, b, and c of F(t) that minimize the following. However, the actual data function f(t)
is not a continuous function but is obtained as m discrete values, so the function Q(a, b,
c) is expressed as the following equation, Q(a, b, c) = _n 〓 ^k=0 {F(t _k )−f(t _k )} ² ...(5), and this Q(a, What is necessary is to find the coefficients a, b, and c that minimize b, c). Therefore, Rewriting this equation (6), we get Since the approximate equation is F(t)=at ² +bt+c (3), the following simultaneous equations can be obtained from equations (3) and (7).

Therefore, the simultaneous equations of equation (8) can be transformed into Gauss−
By solving using the Jordan method, coefficients a, b, and c of the quadratic function F(t), which is an approximate expression of the actual data function f(t), can be obtained. The coefficients a, b, and c of the approximate expression F(t) thus obtained have, for example, the following values: a=0.00238 b=-0.300 c=44.7.

The calculation routine for function approximation based on the determination of an approximation equation that approximates the detected data, that is, the temperature change based on such m pieces of detected data, will be further clarified in the flowchart of FIG.

That is, in block a of FIG. 5, m pieces of temperature data T1, T2, ...Tm are first sampled, and in the next block b, coefficients a, b, and c of the approximation formula F(t) are converted to Approximate formula F is calculated from the simultaneous equations of Eq.
(t).

Subsequently, in block c, a physical quantity, that is, temperature T, after a predetermined threshold time t3 is calculated from the approximate expression F(t) obtained in block b. Naturally, this temperature T is calculated by substituting the threshold time t3 into the fixed approximation formula F(t) of the coefficients a, b, and c, and the calculated value of F(t) is It represents the temperature T reached after the threshold time t3 has elapsed from .

Next, in the determination block d, the calculated reached temperature T is compared with a predetermined dangerous temperature threshold T _D , and when the calculated temperature T is greater than the dangerous temperature threshold T _D , the process proceeds to block e and sends out a danger signal. ,
When the calculated temperature T is below the dangerous temperature threshold _TD , the process proceeds to block f and an uncertainty signal is sent out.

The fire discrimination by the function approximation calculation routine shown in the flowchart of FIG. 5 is further clarified by the time chart of FIG.

In other words, the approximate expression F(t) obtained at the current time “0”
When substituting the threshold time t3 into and calculating the predicted temperature T after the elapse of t3, for example, in the case of the approximation formula F(t) that gives curve A in Figure 6, the temperature T after t3 is calculated as follows. The temperature exceeds the dangerous temperature threshold T _D and is judged to be dangerous.

On the other hand, when the approximate expression F(t) shown by curve B is obtained, the reached temperature T at the threshold time t3 is lower than the dangerous temperature threshold T _D , and in this case it is determined to be uncertain.

Note that the above function approximation method took temperature data as an example, but gas sensor 2 and smoke sensor 3
Arithmetic processing based on the function approximation method is similarly performed on the detected data.

Again, referring to FIG. 2, the difference value calculation determination unit 4
The danger signal from the function approximation calculation discriminator 5 is input to the logic discriminator 6. This logic determining section 6 makes a logical decision to output a fire signal when a danger signal is sent based on different detection data based on at least two sensors.

That is, the danger signal based on the temperature data output from the difference value calculation discrimination section 4 is d1, the danger signal based on the gas concentration is d2, and the danger signal based on the smoke concentration is d3.
In addition, the danger signal based on the temperature output from the function approximation calculation discriminator 5 is d10, the danger signal based on gas concentration is d20, and the danger signal based on smoke concentration is
If d30, danger signals d1 and d10, d2 and d20, d3 based on the same detection data at OR gates 7, 8, and 9
and d30, and as a result, the OR gate 7 outputs the temperature danger signal Et, the OR gate 8 outputs the gas danger signal Eg, and the OR gate 9 outputs the smoke danger signal Es. or gate 7~9
The outputs of are input to AND gates 10, 11, and 12, and AND gate 10 outputs an H level output, that is, Etg signal, when temperature danger signal Et and gas danger signal Eg are obtained, and AND gate 11 outputs an H level output, that is, Etg signal. When the gas danger signal Eg and the smoke danger signal Es are obtained, the H level output, that is, the Egs signal is output, and the AND gate 12 outputs the smoke danger signal Es and the temperature danger signal.
When Et is obtained, an H level output, that is, an Ets signal is output.

The outputs of the AND gates 10 to 12 are collected by an OR gate 13, and a fire signal is outputted as an H level output of the OR gate 14 via an OR gate 14.

In addition to the logical judgment unit 6 which determines and outputs a fire signal based on the at least two danger signals, an uncertain signal is obtained after the fire signal is output based on the danger signals, or if it is determined that it is safe. A logic determining section 25 is provided for continuing to output the fire signal when neither the danger signal nor the uncertainty signal is temporarily obtained.

The logic judgment unit 25 includes an OR gate 15 into which uncertainty signals u1, u2, and u3 corresponding to each detection data from the difference value calculation judgment unit 4 are input, and uncertainty signals u10, u20, and The outputs of the OR gates 15 and 16 are input directly to one of the inputs of the OR gates 19 and 20, and are input to the other via delay circuits 17 and 18. Each output of the OR gates 19 and 20 is connected to one of the inputs of AND gates 21 and 22, and the output of the OR gate 14 is inputted to the other input of the AND gates 21 and 22 via a delay circuit 24. The outputs of the AND gates 21 and 22 are input to an OR gate 23, and the output of the OR gate 23 is input to the other of the OR gate 14, one of which inputs the output of the logic determining section 6.

Further, the delay circuit 17 provided in the logic judgment section 25,
Each of 18 and 24 has a delay function that delays the input signal by one cycle of the calculations in the difference value calculation determining section 4 and the function calculation determining section 4.

Next, the operation of the embodiment shown in FIG. 2 will be explained.

First, each of the temperature sensor 1, gas sensor 2, and smoke sensor 3 outputs an analog detection signal according to temperature, CO gas concentration, and smoke concentration, and each detection signal is sampled at regular intervals and the difference value is The signal is input to the calculation determining section 4. Fire judgment arithmetic processing is executed from when m sampling data are obtained in synchronization with this sampling period, and for example, the temperature danger signal d1 and the smoke danger signal d3 are determined by the difference value calculation routine shown in Fig. 2. When it is sent out, the AND gate 1 is output by the H level output of the OR gates 7 and 9 in the logic discriminator 6.
2 generates an H level output as an Ets signal, and a fire signal is sent out via OR gates 13 and 14.

On the other hand, when the difference value calculation determination section 4 sends out an uncertainty signal, the function approximation calculation determination section 5 executes the calculation process shown in the flowchart of FIG. When a type of danger signal is output, a fire signal is sent out from the logic discriminator 6.

Of course, the logic discriminator 6 is the difference value calculation discriminator 4.
A fire signal is output in the same manner for a combination of two or more different types of danger signals from the function approximation calculation discriminator 5.

Next, the logic judgment unit 25 in the embodiment of FIG.
Explain the operation.

Now, as shown in the graph of Figure 7, the concentration of smoke or CO gas increases over time due to a smoldering fire, and if a smoldering fire ignites at time tn as the smoldering fire progresses, then the generation of hot air flow due to the ignition or Complete combustion causes a temporary decrease in smoke concentration or CO gas concentration. On the other hand, the temperature remains approximately constant during the smoldering fire stage leading to ignition, as shown by the broken line, but changes rapidly after ignition at time tn.

With respect to the changes in smoke concentration, CO gas concentration, and temperature shown in FIG. 7, for example, as shown in the time chart of FIG.
When d3 is output, two danger signals d2 and d3 are obtained, so the logic determining section 6 outputs a fire signal via the OR gate 14. These red flags
d2 and d3 are sent for each cycle of prediction calculation indicated by the clock.

Subsequently, the smoldering fire progresses and the smoke concentration and CO gas concentration decrease due to the ignition at time tn, which causes a switch to transmitting the uncertain signals u2 and u3. In response to the uncertain signals u2 and u3, the OR gate 15 of the logic judgment unit 25 generates an H level output, which is applied to one of the AND gates 21 via the OR gate 19. Since a delayed output based on is obtained from the delay circuit 24, the state is in a permissible state, and a fire signal based on the uncertain signals u2 and u3 is sent via the AND gate 21, the OR gate 23, and the OR gate 14. .

Next, if the difference value calculation determination unit 4 determines that it is safe based on the decrease in smoke and CO gas concentration, and neither the danger signal nor the uncertainty signal is sent out, the output of the OR gate 15 based on the previous uncertainty signal is delayed by one cycle in the delay circuit 17 and given to the OR gate 19, and at this time, the output of the previous fire signal based on the uncertainty signal is sent to the delay circuit 2.
4 is producing a delayed output, the AND gate 21 is in the permissive state, and the H level output based on the uncertain signal delayed by the delay circuit 17 is output to the OR gate 19, AND gate 21, OR gate 23, and further to the OR gate 14. is sent as a fire signal.

Then, after a certain amount of time has elapsed since the ignition,
The smoke concentration and CO gas concentration begin to increase again, and therefore, the uncertainty signals u2 and u3 are sent out again, and then the transmission switches to the danger signals d2 and d3.
Even if a condition temporarily determined to be safe occurs, the output of the fire signal from the OR gate 14 continues.

On the other hand, the output of the fire signal is cut off by the logic determining section 25 in the output state of the danger signal and the uncertainty signal as shown in the time chart of FIG.

Figure 9 shows that an uncertain signal is output after a dangerous signal is sent out, and after an uncertain signal is output, it is determined that it is safe for two or more cycles, and both the dangerous signal and the uncertain signal are sent out. This shows the case where the That is, the output of the fire signal is continued by the delayed output of the delay circuit 17 for one period after the transmission of the uncertain signal is stopped, but in the next period, the delayed output of the delay circuit 17 is also continued. Since there is no fire signal, the logic determining section 25 stops sending out the fire signal.

Note that the operation of the logic judgment unit 25 described above was based on the danger signal and uncertainty signal from the difference value calculation judgment unit 4, but the danger signal and uncertainty signal from the function approximation calculation judgment unit 5 were taken as an example. The same applies to the danger signal and the uncertainty signal, which are a combination of the two, and the output of the fire signal by the logic judgment unit 25 continues unless it is determined that it is safe for two cycles or more after the uncertainty signal is obtained. Ru.

FIG. 10 is a circuit block diagram showing another embodiment of the logic discriminator 6 in the embodiment of FIG.
This embodiment is characterized by logical determination that gives priority to the temperature danger signal.

That is, in the embodiment shown in FIG. 2, logical determination is made to output a fire signal when at least two different types of danger signals are obtained, but in the embodiment shown in FIG. The temperature danger signal Et from the OR gate 13 is directly inputted to the OR gate 13, and the temperature danger signal Et is directly sent as a fire signal.On the other hand, the gas danger signal Eg and the smoke danger signal Es from the OR gates 8 and 9 are input to the AND gate 12.
When both are obtained, a fire signal is output.

Incidentally, in the difference value calculation determination unit 4 in the embodiment shown in FIG. 2, as is clear from the time chart shown in _FIG . Danger by calculating the arrival time t.
However, as another example, the physical quantity after a predetermined time is calculated and the calculated physical quantity is compared with a threshold value to determine whether it is dangerous, uncertain, or safe.
You may decide that it is safe.

This point also applies to the function approximation method shown in the time chart of FIG. Danger and uncertainty are determined by comparison with a threshold value, but conversely, by substituting a dangerous physical quantity, such as the dangerous temperature T _D , into the above equation (3), the dangerous temperature threshold value is determined.
Danger and uncertainty may be determined by calculating the arrival time t to T _D and comparing this arrival time t with a threshold time.

Furthermore, in the calculation determination using the function approximation method, two threshold times, danger and uncertainty, are determined by setting a single threshold time t3, but as with the calculation determination of the difference value, two threshold times can be set. Accordingly, three types of danger, uncertainty, and safety may be determined.

Furthermore, as the difference value method in the difference value calculation and determination section 4, the two-time difference method, which calculates the difference of at least three consecutive data twice, is used in Japanese Patent Application No. 135379/1987, which the inventors of the present invention have already proposed. Risk, uncertainty, and safety may be determined using the value method.

Furthermore, in the embodiment shown in Fig. 2, logical judgments are made based on danger signals obtained by a combination of the difference value method and the function approximation method, but the type of fire judgment obtained by only the difference value method or the function approximation method is different. A fire may be determined when at least two or more danger signals are obtained from different detection data. Furthermore, since the uncertain signal in the above embodiment has a high possibility of fire, the uncertain signal may be treated as a dangerous signal.

Next, to explain the effects of the present invention, there is a danger signal that predicts and calculates the degree of fire danger from detection data based on changes in physical phenomena caused by fire, and determines that it is a fire.
When an uncertain signal that is judged to be between safety and fire is sent out, and an uncertain signal is obtained after sending out a dangerous signal, it is determined that it is safe and the signal is sent out for a certain period of time equivalent to two cycles of predictive calculation. Since the output of the fire signal is not cut off unless a situation occurs in which neither the danger signal nor the uncertainty signal is sent, the smoke concentration is determined after determining the degree of fire danger, as in the case of a transition from a smoldering fire to an ignited fire. It is possible to reliably prevent the output of a fire signal from being cut off even if it is predicted that it is temporarily safe due to a phenomenon such as this, and the reliability in predicting and determining a fire can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a graph showing the change in smoke concentration when a smoldering fire transitions to an ignition fire, Fig. 2 is a circuit block diagram showing an embodiment of the present invention, and Fig. 3 is the same as Fig. 2. FIG. 4 is a flowchart showing the difference value calculation process in the embodiment; FIG. 4 is a time chart showing fire determination by the difference value calculation process in FIG. 2;
The figure is a flowchart showing the function approximation calculation processing in the example of Fig. 2, Fig. 6 is a time chart showing fire judgment by the function approximation calculation processing of Fig. 2, and Fig. 7 is a flowchart showing the function approximation calculation processing in the example of Fig. Time charts showing changes in CO gas concentration, Figures 8 and 9 are time charts showing operation waveforms of the logic judgment section in the embodiment of Fig. 2, and Fig. 10 is a logic judgment used in the embodiment of Fig. 2. FIG. 3 is a circuit block diagram showing another embodiment of the section. 1: Temperature sensor, 2: CO gas sensor, 3: Smoke sensor, 4: Difference value calculation discrimination section, 5: Function approximation calculation discrimination section, 6, 25: Logic discrimination section, 7, 8, 9,
13, 14, 15, 16, 19, 20, 23: OR gate, 10, 11, 12, 21, 22: AND gate.

Claims (1)

[Claims] 1. A detection unit that detects changes in physical phenomena caused by a fire in an analog manner, and a time or a predetermined time until a threshold value for determining a fire is reached based on analog detection data from the detection unit. Predictively calculate the value reached after the passage of time,
a calculation determination unit that sends out a danger signal when the calculation time is within a set time or the reached value is greater than or equal to the set value; and a fire signal that outputs a fire signal in response to the danger signal from the calculation determination unit, and an uncertain signal that follows the fire signal. A logic judgment unit is provided that continues to output the fire signal in response to the input of the signal or the danger signal, and then cuts off the output of the fire signal when the input of the uncertain signal or the danger signal is cut off for a predetermined period of time. A fire alarm device featuring: