JPH0441394B2 - - Google Patents

Description

[Detailed Description of the Invention] a. Industrial Application Field The present invention is a method for determining the degree of danger to humans in the near future based on analog detection data such as temperature detected by a fire detector, concentration of gases such as CO, and smoke concentration. The present invention relates to a fire alarm device that calculates a fire alarm and issues a fire alarm when the degree of danger is above a certain level.

b. Prior Art Conventional fire alarm devices generally use a receiver to determine the on/off signal of a fire detector to notify a fire, but because they rely on the fire detector to determine the presence of a fire, , there are many false alarms due to causes other than fire. Furthermore, if the detection sensitivity is lowered to prevent false alarms, there is a problem in that a time delay occurs in fire detection.

Therefore, in recent years, so-called analog fire alarm devices have been developed in which an analog fire detection signal from a fire detector is sent as is to a receiver, and the receiver determines whether there is a fire. For example, a device has been proposed that detects fire by comparing an analog detection signal from a fire detector with a preset threshold. Figure 1 shows the current time x ₀ detected by the fire detector.
It is a graph showing the temperature rise due to the fire over time. Curve B is detection data in which the temperature rise due to a fire such as a smoldering fire changes slowly, and curve A is detection data in which the temperature rises rapidly after a certain period of time has elapsed from the occurrence of a fire such as an ignition fire. It is. Even though the fire on curve A is the most dangerous, it takes longer to reach the conventional alarm threshold T _A than the fire on curve B, resulting in a delay in issuing a fire alarm. Curve C is detection data from a fire detector installed in a place where there is a temporary or local temperature rise, such as a cooking room, but even though there is no fire, the alarm threshold There was a problem that if the temperature exceeded T _A , it would be judged as a fire and a false alarm would be generated.

c. Purpose of the invention The present invention has been made in view of the above problems.
The purpose of the present invention is to provide a fire alarm system that prevents false alarms due to non-fire causes, quickly determines fire occurrences that pose a high degree of danger to humans, and provides highly reliable alarms.

d. Structure and operation of the invention In order to achieve this object, the present invention secondarily detects changes in physical phenomena in the surrounding environment based on analog detection data such as temperature, smoke concentration, and gas concentration detected by an analog fire detector. is converted into an approximate formula, and from this approximate formula, the degree of danger is determined as the predicted time until the dangerous level is reached, and a fire alarm is issued when the degree of danger is less than a preset time. It is.

Here, the degree of danger is defined as the progression of physical changes in the surrounding environment due to a fire, and the time it takes for the environment to reach a certain dangerous state for humans in the near future. For example, it is defined as the time it takes for an environmental condition to reach a certain dangerous state that is dangerous to humans. For example, to explain the environmental state that is dangerous to humans in terms of temperature, in Figure 1, a dangerous temperature T _D that becomes a dangerous state is set, and the times R ₁ and R ₂ until this dangerous temperature T _D is reached are respectively calculated. This is the degree of danger for fires A and B. Therefore, the smaller the danger value, the higher the danger to humans.

e Examples Examples of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram of a fire alarm system showing one embodiment of the present invention. _1a , _1b ,... _1o are fire detectors that detect fire in an analog manner in proportion to changes in physical phenomena in the surrounding environment due to fire, and detect temperature, gas concentration, or smoke concentration. 2, an A/D conversion circuit 6 that converts the analog value detected by the detection section 2 into a digital value, and a transmission circuit 3 that transmits the detected data. 4 is a fire receiving device using a microcomputer, and is connected to a plurality of fire detectors 1 _a , 1 _b , . . . 1 _o by signal lines. 5 is each fire detector 1 _a , 1 _b
This is a receiving circuit that selects A/D-converted analog detection data from 1 _o for each sensor and sequentially receives the data at fixed time intervals. Detection data for each predetermined time period is input to the storage circuit 7 and stored with an address. Reference numeral 8 denotes an approximate formula conversion circuit, which converts the stored content of the memory circuit 7 into an approximate formula, connects it to the risk calculation circuit 9, and further converts the stored content of the storage circuit 7 into an approximate formula.
The output of the fire determination circuit 10, which determines a fire by comparing the calculated risk value with a preset alarm standard value, drives an alarm circuit 11 consisting of a warning light, a buzzer, etc. That's what I do.

Next, FIG. 3 is a program flow diagram of the approximate expression conversion circuit 8, the degree of danger calculation circuit 9, and the fire determination circuit 10, and the operation of the present invention will be explained based on the program flow diagram of FIG.

Detection data from the fire detectors 1 _a , 1 _b , . . . , 1 _o is selected for each fire detector and sequentially received by the receiving circuit 5 at fixed time intervals. For example, assume that m pieces of detection data from the fire detector 1a are (x ₁ , f _(x1) ) (x ₂ , f _(x2) )...(x _n , f _(xn) ).

Note that x ₁ , x ₂ , ...x _n are detection times, and f _(x1) ,
f _(x2) ...f _(xn) are analog quantities for each detection time. This detection data (x ₁ , f _(x1) ) (x ₂ ,
f _(x2) )...(x _n , f _(xn) ) are stored in the memory circuit 7 and input to block g. Blocks h, i, and j are
This figure shows the process of converting into a second-order approximation formula based on m pieces of detection data input to block g. Block j based on the above m detection data
The calculation method for the simultaneous equations shown in will be explained using the method of least squares. Now, m pieces of detection data (x ₁ , f _(x1) )
Let f (x) be the data function obtained from (x ₂ , f _(x2) )...(x _n , f _{( xn)} ), and the quadratic approximation formula F _(x) of the data function f _(x) is as follows: It is indicated by.

F _(x) = ax ² + bx + c ... (1) Note that a, b, and c are coefficients.

To obtain the approximate formula F _{( x)} for the data function f (x), find the coefficients a, b, and c of F _(x) that minimize ∫(F _(x) −f _(x) ) ² dx. All you have to do is ask. However, the actual data function f _(x) is not a continuous function but is obtained as m discrete values, so the function Q (a, b, c) of a, b, c can be expressed as Expressed as: Q (a, b, c) = _n 〓 ^k=0 (F _(Xk) − f _(xk) ) ² ... (2) a, b, where Q (a, b, c) is the minimum, All you have to do is find c. Accordingly Rewriting equation (3), we get Furthermore, since F _(x) = ax ² + bx + c, equation (1) and
The following simultaneous equations can be obtained from equation (4).

For block h, _n 〓 ^k=0 1, _n 〓 ^k=0 x _k , _n 〓 ^k=0 on the left side of equation (5).
^{x 2} _k , _{n 〓} ^{k=0 x} _{3 k, n} ^〓 _{k =} ⁰
f _(xk) , _n 〓 ^k=0 x _k f _(xk) , _n 〓 ^k=0 x ² _k f _(xk) are calculated from the detected data of block g. Block j converts the simultaneous equations of equation (5) into Gaussian equations using the left side of equation (5) calculated in block h and the right side of equation (5) calculated in block i.
Coefficients a, b, c of the quadratic function F _{(x) =} ax ² + bx + c, which is calculated using the Jordan method and is an approximate expression of the data function f (x)
I'm looking for.

Figure 4 is a graph of an actual expanding fire showing the temperature rise over time, and the graph approximated by a quadratic function after passing through blocks h, i, and j from the detection data in Figure 4 is Based on the detection data shown in FIG. 4, the values of coefficients a, b, and c of the quadratic approximation formula F _(x) are calculated using the calculation method described above. a=0.00238 b=- 0.300 c=44.7 ...(6) is obtained.

Blocks l, u, v, and w show the process of calculating the degree of risk R based on the values of a, b, and c obtained in block j, and are obtained from the approximate formula in Figure 5 (6 ) Using the values of formulas a, b, and c, we will explain how to calculate the degree of risk R. First, if the dangerous temperature that causes a dangerous environmental condition to humans is T _D , the degree of risk R is Temperature T _D
Since it is the time it takes to reach , the following equation F _(x) = T _D ...(7) is obtained, and it can be found by solving this equation (7). In other words, by substituting equation (7) into equation (1), we get ax ² +bx-(T _D -c)=0...(8), and the risk R is the value obtained from equation (8) for x,
In other words, since the time x to reach the dangerous temperature T _D is the risk level R, R=-b±√ ² +4( _D -)/2a...(
9) is obtained as.

Therefore, the value of the dangerous temperature T _D set in advance,
The value of the degree of risk R can be calculated by substituting the values of coefficients a, b, and c of the quadratic approximation formula F _(x) found in block j into equation (9).

The determination of the risk level R will be explained below.

First, in the calculation of blocks h, i, and j, coefficients a, b,
When c is determined, the value of b ² + 4a (T _D - c) ... (11) is calculated in block l, and this value is
Then, it is determined whether b ² +4a(T _D −c)>0 (12). Here, in equation (9), it is only necessary to proceed with the calculation when the value of the risk level R becomes a real number, that is, when the value of equation (11) becomes a positive number. Therefore _, if equation (11) is a negative number, for example, detection data such as curve C _shown in FIG _. Extract detection data within a predetermined time from . Here, if we take the values of a, b, and c in equation (6) as an example and perform the calculation in block l, we get b ² + 4a (T _D - c) = 0.807... (13), and in block u It is determined that it is greater than zero, and the process proceeds to block v, where it is further determined that -b+ ^√2 +4( _D -)>0...(14). Similarly, when we substitute the values of a, b, and c to determine equation (14), we get -b+ ^√2 +4( _D -)=1.20...(15), which is larger than zero, so we proceed to block w and are in danger. Calculate the value of degree R. The values of a, b, c
Substituting into equation (9), R = -b + √ ² + 4 ( _D -) / 2a = 252 ... (16) This result is compared with the value of the reference value R _s set in advance in block p. . For example, the reference value R _s
If it is set to 360, when R≦R _s , it is determined that there is a fire in block p, and the process proceeds to block q, where an alarm is displayed by a buzzer or warning light.

Here, the processing shown in Fig. 3 can be performed on a computer by extracting and inputting the detection data at predetermined time intervals regarding the analog fire detection data obtained in the actual fire experiment as shown in Fig. 4. When the simulation was carried out, the time A when the detected temperature rose to about 57℃, that is, the time when the temperature detection data up to about 57℃ was input and calculated, was calculated as the predicted time until the dangerous temperature T _D was reached. When the risk level R became less than the reference value (reference time) R _S , a fire alarm could be issued.

Therefore, as shown in Figure 4, in conventional thermal fire alarm systems, the threshold temperature at point B for determining a fire is
Compared to the case where the fire alarm was not displayed until the temperature rose to 75°C, the present invention allows the fire alarm to be issued at the very early point of point A.

Incidentally, if the dangerous temperature T _D is lowered, the risk level R calculated as the predicted time will be shortened, so that a fire can be determined and an alarm can be issued at an earlier stage. On the other hand, the dangerous temperature
If you set the reference value (reference time) R _S to a longer value without changing T _D , you can similarly determine that there is a fire and issue an alarm at an earlier stage. However, if the dangerous temperature T _D is lowered too much or the reference value R is made too long, false alarms are likely to occur due to noise, etc., so it is necessary to keep it at an appropriate value.

In addition, even if an abnormality such as curve C shown in Figure 1, in which the temperature temporarily rises due to noise etc. during non-fire conditions, occurs, the abnormality accounts for multiple pieces of detected data used to find the coefficients of the quadratic function approximation formula. Due to the small proportion of data, its influence is sufficiently suppressed;
The risk level R, which is calculated by including temporary abnormal values, decreases slightly, but it does not fall below the standard value R _S.
It is possible to reliably prevent false alarms due to non-fire causes.

In addition, above, we have explained using a quadratic function as an example of an approximation formula calculated based on analog detection data from an analog fire detector. It will be more effective if you try to find the degree.

For example, Fig. 8 is a graph showing the temperature rise at _the fire point over time It becomes like this.

F′ _(x) =2.0×10 ^-4 x ⁵ −1.3×10 ^-2 x ⁴ +2.8×10x ³ −2.2x ² +8.1x+32 ……(17) Approximate formula F′ _{(x )} If the degree of risk is determined from the coefficient, fire judgment can be made more reliably and quickly.

FIG. 6 is a block diagram showing another embodiment of the present invention, which is characterized in that the A/D conversion circuit 6 of the embodiment shown in FIG. 2 is incorporated into the fire receiving device 4. 1 _a , 1 _b , ... 1 _o are fire detectors that detect in an analog manner in proportion to physical changes in the surrounding environment due to fire, and a detection unit 2 that detects smoke concentration, gas concentration, temperature, etc. A transmission circuit 3 for transmitting analog data detected by the detection section 2 is built-in.
Reference numeral 4 denotes a fire receiving device having a built-in microcomputer, and is connected to a plurality of fire detectors 1 _a , 1 _b , . . . 1 _o by signal lines. 5 is fire detector _1a ,
A receiving circuit that selects analog detection data from 1 _b ,...1 _o for each fire detector and receives it sequentially at fixed time intervals, and converts the analog value of the detection data into a digital value. /D
It is connected to the conversion circuit 6. Reference numeral 7 denotes a memory circuit, which stores the detected value for each sensor with an address as data for a certain period of time, and converts it into an approximate formula based on the stored contents of the memory circuit 7. It is connected to the degree calculation circuit 9. Further, the output of a fire determination circuit 10 that determines a fire by comparing the calculated risk value with a preset reference value is used to drive an alarm circuit 11 such as a warning light or a buzzer.

Therefore, in the embodiment shown in FIG. 6, by incorporating the A/D conversion circuit 6 into the fire receiving device 4, the circuit configuration of the fire detector can be made simple and small in size. Moreover, cost reduction can be achieved.

FIG. 7 is a block diagram showing another embodiment according to the present invention. Fire detectors 1 _a , 1 _b , . . . 1 are characterized in that the memory capacity stored in the memory circuit 7 is reduced, and detect in an analog manner proportional to changes in physical phenomena in the surrounding environment due to fire. The analog detection data from _o is passed through the A/D conversion circuit 6, and the analog detection data below a certain level set in advance by the level judgment circuit 13 is erased by the erasing circuit 14.
The memory circuit 7 stores only the data above a certain level that is considered to be caused by the occurrence of a fire, and based on this memory content, the approximate equation conversion circuit 8
, and is converted to an approximate expression.

It should be noted that there is a danger calculation circuit 9 that calculates the danger, a fire judgment circuit 10 that issues a fire alarm by comparing the calculated danger value with a preset reference value, and an alarm circuit 11. has the same configuration as the embodiment shown in FIG.

Also, as shown by dotted lines, fire detectors 1 _a , 1 _b ,
...1 The detected data from _o is input to the level judgment circuit 13, and only the data above a preset reference level value is sent to the storage circuit 7 via the A/D conversion circuit 6.
The data may be transmitted to.

Therefore, in the embodiment of FIG. 7, more fire detectors can be connected with limited storage capacity.

f. Effects of the Invention Next, to explain the effects of the present invention, the time required for the environmental condition to reach a dangerous state for humans in the near future due to the progress of changes in the physical phenomena of the surrounding environment due to a fire is defined as the degree of danger. Based on detection data such as temperature, gas concentration, smoke concentration, etc. detected by the sensor, changes in physical phenomena in the surrounding environment are converted into a quadratic approximation formula, and this approximation formula is used to predict until a dangerous level is reached. By determining the degree of danger in terms of time and issuing a fire alarm when the degree of danger is below a preset reference value (reference time),
As is clear from the explanation using the example of an actual spreading fire shown in FIG. 4, the effect of quickly and reliably detecting the occurrence of a fire that poses a high degree of danger to humans can be obtained. Further, it is possible to prevent false alarms due to non-fires caused by temporary increases in smoke concentration due to cigarette smoke or local temperature increases in the cooking room, etc., and a highly reliable fire alarm system can be obtained.

[Brief explanation of drawings]

Fig. 1 shows detection data detected by an analog fire detector, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a program flow diagram for the embodiment of Fig. 2, and Fig. 4 is a graph showing an actual expanding fire, FIG. 5 is a graph approximately showing the expanding fire in FIG. 4, FIG. 6 is a block diagram showing another embodiment of the present invention, and FIG. FIG. 8, a block diagram showing another embodiment of the invention, is a graph showing an actual fire. 1 _a , 1 _b , 1 _o ... fire detector, 2 ... detection section, 3 ... transmission circuit, 4 ... fire receiving device, 5 ...
. . . Receiving circuit, 6 . ...Level judgment circuit, 14...Elimination circuit.

Claims (1)

[Scope of Claims] 1. A fire alarm system comprising an analog fire detector that detects the amount of change in an analog manner in proportion to a change in physical phenomena in the surrounding environment due to a fire, and a fire receiving device connected to a signal line. , a memory circuit that stores detection data from the analog fire detector over a certain period of time, and approximates temporal changes in physical phenomena in the surrounding environment to a quadratic function based on the detection data stored in the memory circuit. an approximation formula conversion circuit for calculating the degree of danger, which is the time required for a physical change in the surrounding environment to reach a preset threshold value, based on the approximation formula; and the degree of danger calculation circuit. a fire determination circuit that compares the degree of danger obtained by the calculation with a preset reference value and determines that there is a fire if the degree of danger is smaller than the reference value; and when the fire determination circuit determines that there is a fire. A fire alarm device characterized in that it is configured to issue a fire alarm.