JPH0237099Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses the average value of analog fire detection data to periodically set alarm reference values to determine fires, and to prevent false alarms due to changes in atmospheric pressure. The present invention relates to an analog fire alarm device that changes the set value of the alarm reference value accordingly.

The proponents of this application have proposed a so-called analog fire alarm system that determines whether a fire is occurring by transmitting an analog fire detection signal corresponding to temperature, smoke concentration, etc. detected by a fire detector directly to a receiver. (For example, Utility Model Application No. 58-10708). In this analog fire alarm system, analog fire data is sampled multiple times at regular intervals as an alarm standard value, and an average value is obtained. A value obtained by adding a predetermined constant value is used as an alarm standard value, and a fire is determined by comparison with fire data.

However, when using an analog fire detector, for example, an ionization type smoke detector, there is a phenomenon in which a detection signal exceeding the alarm standard value is output due to changes in atmospheric pressure even if no smoke or insects enter. It was observed.

That is, the ionization type smoke detector has a structure in which an internal ion chamber into which smoke does not flow and an external ion chamber into which smoke flows are ionized by a radiation source to detect changes in chamber voltage due to smoke inflow. Therefore, there was a fear that a sudden change in atmospheric pressure would cause a change in chamber voltage.

The present invention was devised in view of these problems, and it is an object of the present invention to provide an analog fire alarm device that prevents false alarms due to changes in atmospheric pressure.

In order to achieve this purpose, the present invention detects the atmospheric pressure at regular intervals with a barometric pressure detector, selects a predetermined correction coefficient according to the detected atmospheric pressure, and corrects the alarm reference value. This prevents false alarms from occurring by setting alarm reference values that follow changes.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. First, to explain the configuration, 1 is a receiver, and a smoke detector 2 and an atmospheric pressure sensor 3 are connected to the receiver 1 via a signal line. Here, the smoke detector 2 is an ionization type smoke detector that outputs a fire detection signal according to the smoke concentration caused by the fire, and the atmospheric pressure sensor 3 is used to detect a range of atmospheric pressure changes according to weather conditions, for example, 900 to It uses a sensor that outputs a barometric pressure detection signal in response to barometric pressure changes in the range of 1100 millibars.

The output of the smoke detector 2 and atmospheric pressure sensor 3 is sent to the receiver 1.
The analog fire detection signal from the smoke detector 2 and the atmospheric pressure detection signal from the atmospheric pressure sensor 3 are inputted to the A/D converter 4, which converts each of the analog fire detection signal from the smoke detector 2 and the atmospheric pressure detection signal from the atmospheric pressure sensor 3 into digital signals and outputs the digital signals at regular intervals.

Reference numeral 5 denotes a reception processing section, which can be realized, for example, by program control of a microcomputer. That is, the reception processing unit 5 includes a smoke data memory 6 that stores smoke data detected by the smoke detector 2 at regular intervals, and an atmospheric pressure data memory 7 that stores atmospheric pressure data detected by the atmospheric pressure sensor 3 at regular intervals. is provided. The sampling period of the smoke data stored in the smoke data memory 6 is carried out at a predetermined constant period T, and the smoke data memory 6 has two samples of current smoke data and previous smoke data.
It has a function to sequentially store smoke data. The smoke data thus detected at regular intervals T and stored in the smoke data memory 6 is output to the comparison circuit 11 and compared with the alarm reference value Sp, which will be explained later.

On the other hand, the sampling period of the atmospheric pressure data stored in the atmospheric pressure data memory 7 is performed every predetermined period T in synchronization with the sampling of the smoke data mentioned above, and the atmospheric pressure data detected at every constant period T is It is output to the correction coefficient memory 8. The correction coefficient memory 8 has a function of reading out a correction coefficient for correcting the alarm value Sp according to the detected atmospheric pressure data using the atmospheric pressure data as address data.

Here, to explain the correction coefficients stored in the correction coefficient memory 8, first, the change in the output of the ionization type smoke detector with respect to the atmospheric pressure P is approximately proportional to the increase in the atmospheric pressure P, as shown in the experimental data in Fig. 2. It is a characteristic that increases as

Therefore, in order to obtain a correction coefficient for changes in atmospheric pressure, for example, the standard atmospheric pressure of Pi = 1015 millibar is used as a reference, and the correction coefficient Ki at this standard atmospheric pressure Pi is set to Ki.
= 1, that is, no correction is performed, then for pressures P1 to Pi- ₁ below the standard pressure Pi, decimal digit correction coefficients K1 to Ki- ₁ are determined to be 1 or less,
On the other hand, for atmospheric pressures Pi+ ₁ to Pm that are equal to or higher than the standard atmospheric pressure Pi, correction coefficients Ki+ ₁ to Km that are equal to or greater than 1 can be determined.

Therefore, as shown in FIG. 3, the correction coefficient memory 8 stores in advance correction coefficients K1 to Km determined based on the experimental data in FIG. 2 using the atmospheric pressures P1 to Pm detected by the atmospheric pressure sensor 3 as addresses. When, for example, detected atmospheric pressure data Pi is given from the atmospheric pressure data memory 7, a correction coefficient Ki is read out from the correction coefficient memory 8 using the atmospheric pressure data Pi as address data, and is output to the alarm value Sp calculation circuit 10.

Referring again to FIG. 1, 9 is the reference addition value α
This is a reference addition value setting circuit for setting the reference addition value α, and a constant value corresponding to the detection sensitivity of fire discrimination is used as the reference addition value α. In other words, if Si is the normal output of the sensor at standard atmospheric pressure Pi = 1015 millibar, and Sr is the alarm value corresponding to the sensor output at a smoke density with a light attenuation rate of 5%/m, which is the standard type 1 sensitivity,
The reference addition value α is determined by the difference between the two, α=Sr−Si. 10 is an alarm value Sp calculation circuit;
The reference value So, which is the previous smoke data stored in the smoke data memory 6, the correction coefficient K read out based on the atmospheric pressure data from the correction coefficient memory 8, and the reference addition value α from the reference addition value setting circuit 9. Input each and calculate the alarm value Sp as Sp=So+Kα.

The meaning of such correction of the alarm reference value Sp will be explained in more detail as follows.

Figure 6 shows the atmospheric pressure on the horizontal axis and the detection output of the sensor on the vertical axis, and shows the normal output of the sensor when the atmospheric pressure increases from P1 to Pi to Pm, the alarm reference value before correction, and the corrected alarm. It shows the change in the reference value Sp.

That is, the correction coefficient K is K=1 at the standard atmospheric pressure Pi, and no correction is performed based on the atmospheric pressure.

At a pressure P1 lower than the standard pressure Pi, the correction coefficient K has a value smaller than 1. Therefore, the alarm reference value shown by the broken line is corrected to a lower value by multiplying α by a correction coefficient smaller than 1.

On the other hand, when the atmospheric pressure Pm is higher than the standard atmospheric pressure Pi, the correction coefficient K is larger than 1, and the alarm value indicated by the broken line is corrected to a higher value by multiplying α by the correction coefficient K larger than 1.

Therefore, the correction coefficient memory 8 shown in FIG.
This constitutes the reference value correction means of the present invention.

Reference numeral 11 denotes a comparison circuit, which inputs the current smoke data stored in the smoke data memory and compares it with the alarm value Sp from the alarm value Sp calculation circuit 10, and when the smoke data exceeds the alarm value Sp. At the same time, a comparison output is generated, and a fire alarm is issued by operating a fire display section 13 via an interface 12.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

First, smoke data Mn and atmospheric pressure data Pn are detected at predetermined regular intervals T as shown in block a. The operation is commanded at regular intervals T, and smoke data Mn and atmospheric pressure Pn detected by the smoke detector 2 and atmospheric pressure sensor 3 are written into the smoke data memory 6 and the atmospheric pressure data memory 7, respectively, and new smoke data is written to the smoke data memory 6 and atmospheric pressure data memory 7, respectively. When writing smoke data, the previously detected smoke data Mn− ₁
It performs sequential memorization that leaves the information intact.

When the sampling of smoke data Mn and pressure data Pn shown in block a is completed, the process proceeds to block b, where the previous smoke data Mn stored in the smoke data memory 6 is set to the reference value So used for calculating the alarm value Sp. Then, in block c, the detected atmospheric pressure data Pn is used as address data to read out the correction coefficient K corresponding to the detected atmospheric pressure stored in the correction coefficient memory 8, and further, in block d, the standard addition value setting circuit 9 performs standard addition. Read the value α.

The reference values obtained from such blocks b to d
Based on So, the correction coefficient k, and the reference addition value α, the alarm value Sp is calculated in block e by the arithmetic processing of the alarm value Sp calculation circuit 10.

Next, the process proceeds to discrimination block f, where the alarm value Sp calculated in block e is compared with the current smoke data Mn sampled in block a, and the smoke data Mn is
If the smoke data Mn is greater than or equal to the alarm value Sp, proceed to block g and issue a fire alarm, while the smoke data Mn is greater than the alarm value Sp.
When it is below , the alarm is not issued and the process directly proceeds to block h, where the current smoke data Mn is replaced with the previous smoke data Mn- ₁ ,
Returning again to the sampling of the next smoke data and pressure data in block a, the above-described operation is repeated at regular intervals.

FIG. 5 is a time chart showing the time change of the alarm value Sp based on the detected atmospheric pressure according to the above embodiment. For the sake of simplicity, the output of the smoke detector does not change and remains at a constant value. It shows the current state.

That is, if a pressure change occurs as shown in Figure 5a, the pressure fluctuation △P with respect to the standard pressure Pi will be as shown in Figure 5b, and when the pressure fluctuation △P is positive, the correction coefficient k is 1. When the above value is obtained and the atmospheric pressure fluctuation ΔP is negative, the correction coefficient K takes a value of 1 or less decimal places.

Therefore, as shown in Figure 5c, the alarm value Sp calculated for such atmospheric pressure fluctuations is calculated by correcting the reference value So given by the previous smoke data (assumed to be constant) with the reference addition value α. It is the value obtained by adding the value αK multiplied by the coefficient k, and the magnitude of αK follows the change in atmospheric pressure, so the alarm value Sp has a value that corresponds to the change in atmospheric pressure.

Therefore, by changing the alarm value Sp in accordance with changes in the atmospheric pressure P, it is possible to reliably prevent a malfunction in which fire detection data that has changed due to the atmospheric pressure is mistakenly determined to be a signal change due to a fire. Furthermore, the first
In the embodiment shown in the figure, the correction coefficient memory 8 and the reference addition value setting circuit 9 are provided separately, but in other embodiments, the value αK obtained by multiplying the reference addition value α and the correction coefficient K
By storing the atmospheric pressure data in the memory as address data, the correction coefficient memory 8 and the reference addition value setting circuit 9 can be realized in one circuit.

In addition, the above embodiment takes as an example a method in which the analog detection signal of a smoke detector is input directly to the receiver, but as shown in Utility Application No. 10708/1983, the receiver is powered on. A fire system in which multiple analog fire detectors are connected in parallel via a dual-purpose signal line, the detectors are sequentially called by the receiver, and the called fire detector converts the analog fire detection signal into a digital signal and sends it to the receiver. Regarding the alarm equipment, a similar barometric pressure sensor may be provided, and the alarm reference value may be corrected based on the smoke data from the fire detector called out in accordance with the detected atmospheric pressure.

Next, to explain the effects of the present invention, the atmospheric pressure is detected at regular intervals using a barometric pressure detector, a preset correction coefficient is selected according to the detected atmospheric pressure, and the alarm standard value is corrected using this correction coefficient. Because of this,
Even if the smoke data changes significantly due to changes in atmospheric pressure, the alarm standard value will be changed to follow the change in atmospheric pressure.
To reliably prevent an increase in smoke data due to changes in atmospheric pressure from being mistakenly determined as a fire, and to greatly improve the reliability of fire alarm systems that input analog fire detection signals to receivers to determine fires. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a graph showing changes in the output of a smoke detector with respect to changes in atmospheric pressure P, and Fig. 3 is a correction coefficient stored in the correction coefficient memory. An explanatory diagram showing an example of data, Fig. 4 is a flowchart showing fire discrimination processing according to the embodiment of Fig. 1, and Fig. 5 is a reference value.
FIG. 6 is a time chart showing changes in alarm value Sp with respect to atmospheric pressure P when So is constant, and is a diagram explaining the principle of alarm reference value correction according to the present invention. 1...Receiver, 2...Smoke detector, 3...Atmospheric pressure sensor, 4...A/D converter, 5...Reception processing unit,
6... Smoke data memory, 7... Atmospheric pressure data memory, 8... Correction coefficient memory, 9... Reference addition value setting circuit, 10... Alarm value Sp calculation circuit, 11...
Comparison circuit, 12...interface, 13...fire display section.

Claims (1)

[Scope of Claim for Utility Model Registration] Detection data from an analog fire detector is detected at predetermined intervals to calculate an alarm reference value, and the fire detection data is compared with the alarm reference value to determine a fire. In an analog fire alarm device, an air pressure detector that detects air pressure, a correction coefficient determining means that determines a correction coefficient for the alarm reference value according to the air pressure detected by the air pressure detector, and a correction coefficient that is determined by the correction coefficient determining means. An analog fire alarm device comprising: reference value correction means for correcting the alarm reference value at regular intervals using the corrected correction coefficient.