JPH0477956B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fire alarm system that activates a fire alarm, fire extinguishing equipment, etc. from analog detection signals of temperature and smoke density associated with a fire.

(Prior art) Conventionally, a combined fire detector detects the temperature and smoke density associated with a fire, and sends a switching signal when the threshold temperature is reached and a switching signal when the threshold smoke density is reached. It is known that a fire is determined based on the logical product (AND) or logical sum (OR) of both signals, and it is also possible to select either the logical product output or the logical sum output using a switch. There is.

On the other hand, Japanese Patent Laid-Open No. 59-72597 is known to eliminate non-fire alarms by switching to increase the smoke detection sensitivity as the temperature increases.

(Problem to be Solved by the Invention) However, in the conventional fire alarm system using such a composite fire detector, when a fire is determined based on the logical product of temperature and smoke concentration, the fire is determined by the logical product of temperature and smoke concentration. This has the advantage of being reliable and preventing non-fire alarms, but on the other hand, it causes a time delay in fire detection. Furthermore, when the logical sum of temperature and smoke concentration is calculated, it is possible to improve the responsiveness of fire detection, but there is a problem in terms of reliability.

Furthermore, even with the method of switching the smoke detection sensitivity based on temperature information, the smoke sensitivity is increased based on the temperature with a time delay, so although the reliability is high, there is a problem that the responsiveness of fire detection is low. .

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned conventional problems, and has been developed to provide both highly responsive smoke concentration detection characteristics and highly reliable temperature detection characteristics. It is an object of the present invention to provide a fire alarm system that can effectively utilize the advantages to provide an alarm through early detection of a fire and interlock control of a fire extinguishing system, etc. through reliable fire detection.

In order to achieve this objective, the present invention includes:
A smoke detection section that outputs an analog signal proportional to the smoke concentration caused by the fire and a temperature detection section that outputs an analog signal proportional to the temperature caused by the fire are installed in the same monitoring section, and the smoke detection section and the temperature detection section output the analog signal proportional to the temperature caused by the fire. In a fire alarm system equipped with a reception control panel that receives analog signals of After determining that there is a fire, the temperature is monitored using an analog signal, and when the temperature exceeds the operating level, a decision is made to control the activation of a starting device such as a fire extinguishing equipment.

(Embodiment) FIG. 1 is a circuit block diagram showing an embodiment of a composite fire detector equipped with a smoke detection section and a temperature detection section.

First, the structure will be explained. The composite fire detector is composed of a power supply section 10, a smoke detection section 20, and a temperature detection section 30.

The power supply section 10 includes a rectifier circuit 11 and a noise absorption circuit 1.
2 and a constant voltage circuit 13 are provided, and receive power supply through power lines l1 and l2 drawn out from the reception control panel, and the constant voltage circuit 13 provides, for example, Vcc=
Produces a constant voltage output of 10V.

The smoke detection unit 20 is provided with a light emitting element 22 that is supplied with a power supply voltage Vcc through a diode D1 and is driven to emit light intermittently by an oscillation circuit 21, and a light receiving element 23 that extracts a light receiving output according to the smoke concentration. . The light-receiving element 23 is arranged at a position where the light from the light-emitting element 22 does not directly enter, and receives scattered light from smoke particles flowing into the sensor to obtain a light-receiving current proportional to the smoke concentration. Light receiving element 23
The output of the light emitting element 22 is amplified by the amplifier circuit 24.
Since the is driven intermittently, the output of the amplifier circuit 24 is converted into a continuous signal by the sample and hold circuit 25, and is further passed through the impedance converter 26 to the operational amplifier 27, the resistors R1 to R3, and the transistor Tr1. The current is applied to the conversion circuit 28, and the current conversion circuit 28 is supplied to the impedance conversion section 2.
An output current Is corresponding to a detection voltage Vs proportional to the smoke concentration from the signal line 13 is made to flow through a signal line 13 drawn out from the reception control panel.

On the other hand, the temperature detection section 30 is provided with a Zener type temperature detection element 32, and the voltage at the connection point with the resistor R4 is inputted to the amplifier circuit 33 as a temperature detection voltage Vz. Further, a reference voltage circuit 31 is provided, and the reference voltage Vr of the reference voltage circuit 31 is applied to the amplifier circuit 33. The amplifier circuit 33 compares and amplifies the temperature detection voltage Vz and the reference voltage Vr, and outputs the amplified output voltage.
Vh through the diode D3 to the operational amplifier 34,
It is supplied to a current conversion circuit 35 including a transistor Tr2 and resistors R5 to R7, and the current conversion circuit 3
5 causes an analog current Ih proportional to the detected temperature to flow through the signal line l4 drawn out from the reception control panel.

The output characteristics of the analog current with respect to the smoke concentration and temperature of the combined fire detector shown in Figure 1 are shown in Figure 2.
The settings are as shown in the figure.

First, the analog output current for temperature and smoke concentration has a span of, for example, 4 to 20 mA, and the characteristics of the output characteristics of smoke concentration and temperature are for fire judgment in the receiving control panel, which will be explained later. It is possible to set a common threshold level for both smoke density and temperature.

In other words, regarding the smoke density output characteristics shown on the left,
If we set a linear output characteristic of 4 mA at a smoke density of 0%/m, the threshold level for fire judgment will be a smoke density of 5%/m.
m gives the caution signal level, 10%/m gives the fire alarm level, and 20%/m gives the activation level of fire extinguishing equipment, etc. The analog currents for these three threshold levels will be 7mA, 10mA, and 16mA.

On the other hand, regarding the temperature output characteristics shown on the right,
For example, the caution signal level is 55℃, and the fire alarm level is
Assuming that the operating level of fire extinguishing equipment is 100°C, 7mA at 55°C, which is the caution signal level, is 70°C.
Linear output characteristics will be set: 10 mA at 70°C, which is the fire alarm level, and 16 mA at 100°C, which is the activation level for fire extinguishing equipment. If these three threshold levels are shared by smoke density and temperature, the temperature corresponding to an analog current of 4 mA in the temperature output characteristic will be 40°C, and as a result, the temperature detection will be 40°C.
The above is possible.

The smoke concentration and temperature output characteristics shown in FIG. Reference voltage circuit 31, amplifier circuit 33, and current conversion circuit 35 in
This can be realized by setting the circuit constants.

To explain specifically, first of all, regarding smoke density,
The relationship between the output voltage of the sample and hold circuit 25 and the smoke density is shown in FIG. In other words, when the smoke density is 0%/m, the leakage light generates a detection voltage of, for example, 2V, and the sensor has an output characteristic that increases linearly as the smoke density increases from 2V due to the leakage light. . This sample hold circuit 2
The output voltage of No. 5 is given to the current conversion circuit 28 via the impedance conversion section 26 as the detection voltage Vs.

The conversion characteristics of the current conversion circuit 28, that is, the voltage-current conversion characteristics, are determined by the resistor R3 connected to the emitter of the transistor Tr1, and the output current Is is expressed as Is=Vs/R3 (1). For example, if the detection voltage Vs when the smoke density is 0%/m is Vs = 2V as shown in Figure 3, then by setting the resistance R3 = 500Ω, the output current Is = 4mA from equation (1). becomes. In addition, the detection voltage Vs = 3.5V at a smoke density of 5%/m giving a warning signal level
Therefore, the output current Is=7 mA, and the output characteristic of smoke density shown on the left side of FIG. 2 can be realized by using the voltage-current conversion characteristic according to equation (1).

Note that the voltage dividing resistors R1 and R2 provided at the input stage of the operational amplifier 27 have a minimum current of 4 m when the smoke density is 0%/m.
This is to ensure A, and a detection voltage Vs=2V corresponding to a smoke density of 0%/m is created in a pseudo manner. Specifically, if Vcc=10V, R1=
By setting 40KΩ and R2=10KΩ, a divided voltage of 2V can be obtained.

Next, the output characteristics of the temperature detection section 30 are determined as follows.

First, the detection characteristics of the Zener type temperature detection element 32 are as shown in FIG. 4, for example, and the relationship between the temperature detection voltage Vz and the ambient temperature T is Vz≒0.01T+2.85 (2) There is.

Here, if the amplification factor of the amplifier circuit 33 is set to 4 times, the output current Ih of the current conversion circuit 35 is given by Ih = {(Vz-Vr) x 4-0.6}/R7...(3) It will be done. Note that 0.6V is the voltage drop caused by the diode D3.

Here, the reference voltage Vr is set to 2.9V by adjusting the volume of the reference voltage circuit 31, and R7=
If it is 200Ω, the temperature detection voltage Vz = 3.25V when the ambient temperature is 40℃ from Fig. 4, so the above-mentioned
Ih=4mA is obtained from equation (3). Furthermore, by substituting the detected voltage Vz = 3.85V at an ambient temperature of 100°C, which provides the operating level of a fire extinguisher, etc., into the above equation (3),
The output current Ih=16 mA, and it is possible to obtain temperature output characteristics that share the same threshold level as the analog output current for smoke density shown in FIG.

In addition, resistors R5 and R6 have a minimum output current Ih = 4m
Resistors R5 and R6 are provided to maintain A, and as shown in Figure 4, the temperature detection voltage Vz that provides the minimum output of 4mA is 3.25V when the ambient temperature is 40°C.
A divided voltage of 3.25V is created by dividing the voltage. For example, when the power supply voltage Vcc = 10V, by setting R5 = 20.7KΩ and R6 = 10KΩ, it is possible to obtain a divided voltage of 3.25V that provides a minimum output of 4mA.

The advantage of having the analog output characteristics of the smoke detector 20 and the temperature detector 30 as output characteristics that allow a common threshold level to be set is that the receiving control panel, which will be explained later, can There is no need to set different threshold levels, and fire judgment processing can be performed more easily.

Of course, in the embodiment shown in FIG.
0 and individual signal lines l3, l4 from the temperature detection unit 30
Since an analog current proportional to the smoke concentration and temperature is outputted, it goes without saying that the output characteristics may have different zero spans for the smoke concentration and temperature.

FIG. 5 is a block diagram showing an embodiment of a reception control panel to which the composite fire detector shown in FIG. 1 is connected by signal lines.

First, to explain the configuration, power lines l1 and l2 are drawn out from the reception control panel 1, and these power lines l1 and
The composite fire detector 2a, 2 shown in FIG.
b, 2c... are connected in parallel and receive power supply. From each of the composite fire detectors 2a, 2b, . ing.

The reception control panel 1 is provided with a power supply circuit consisting of a transformer 40, a rectifier circuit 41, and a stabilized power supply 42, and when a power switch 43 is turned on, a constant DC power supply voltage is supplied from the stabilized power supply 42 in response to the supply of commercial AC 100V. is supplied to the composite fire detectors 2a, 2b, .

On the other hand, analog output signal lines l3 and l4 from the composite fire detectors 2a, 2b, . The signals are sequentially extracted by scanning for each device, converted into digital signals by the A/D converter 45, and sent to the CPU 47 via the I/O port 46.
given to.

The analog signals of smoke concentration and temperature for each sensor that are given to the CPU 47 in this way have the characteristics shown in FIG. , the fire alarm level, and the fire extinguishing system operation level are set in common, and these threshold levels are used to execute the next fire judgment and control processing of the fire extinguishing system, etc.

First, it is monitored whether the smoke density or temperature analog signal exceeds a warning signal level.

Second, when the smoke density or temperature analog signal exceeds the caution signal level, a caution warning is issued as a pre-alarm.

Third, it monitors whether the analog signal exceeds the fire alarm level, and issues a fire alarm if it exceeds the fire alarm level.

Fourthly, after the fire alarm level is exceeded, the temperature analog signal is monitored to see if it exceeds the activation level of the fire extinguishing system, etc., and when the temperature exceeds the activation level, the activation control of the fire extinguishing system and starting device is performed.

For the first to fourth fire control processing by the CPU 47, an indicator 50 and an alarm 51 are provided via the I/O port 48 and output interface 49, and the I/O port 52 and A control relay circuit 54 is provided via the output interface 53, and by relay control of the control relay circuit 54 by the CPU 47, fire alarm and fire control processing such as activating an external alarm, closing a fire door, opening an escape exit, and activating a fire extinguishing device is performed. We are making it possible to do so. Additionally, there is a ROM/ROM for temporarily storing control programs and analog data for fire control processing.
A RAM 55 and a timer 56 for obtaining time information are provided.

Next, fire judgment processing and fire control processing based on analog signals of smoke concentration and temperature according to the above embodiment will be explained.

Figure 6 shows the CPU installed in the reception control panel 1 in Figure 5.
47 is a flowchart showing the program control processing of No. 47.

First, in block 60, the temperature analog output current Ih and the smoke analog output current Is output from a specific composite fire detector are read. Next, in judgment block 61, the control is compared with 7 mA set as the caution signal level, and if either the temperature analog output Ih or the smoke analog output Is is equal to or higher than 7 mA, which gives the caution signal level, the process proceeds to the next judgment block 62.

At this time, if the caution signal level exceeds 7 mA but does not reach the fire alarm level of 10 mA, the process proceeds to block 63 to issue a caution alarm.

On the other hand, if the fire alarm level exceeds 10 mA, the process proceeds to a judgment block 64, where the temperature analog output Ih is compared with the activation level of a fire extinguisher or other starting device of 16 mA.
If in judgment block 62 the temperature or smoke density analog output Ih or Is exceeds the fire alarm level of 10 mA but the temperature analog output Ih is less than 16 mA, the process proceeds to block 65 to issue a fire alarm.

Temperature analog output Ih is 16m in discrimination block 64
Once A is exceeded, block 66 activates an activation device such as a fire extinguisher.

Figure 7 is an example of a time chart showing changes over time in analog outputs of smoke concentration and temperature from a composite fire detector during a fire.Normally, the analog output Is of smoke concentration changes first; The temperature analog output Ih increases with a delay, and the smoke concentration analog output Is approaches saturation as time passes, but the temperature analog output Ih increases quadratically with the passage of time. There is.

In response to such changes in the smoke density and temperature analog outputs Is and Ih during a fire, in the present invention, first, when the smoke analog output Is reaches the caution signal level at time t1, a caution alarm is issued, Then at time t2
When the smoke density analog output Is reaches the fire alarm level, a fire alarm is issued. After a fire alarm is issued based on the smoke density analog output Is in this way, monitoring switches to only the temperature analog output Ih. When the temperature analog output Ih reaches the operating level of the fire extinguisher, etc. at time t3, control such as activation of the fire extinguisher is performed.

Figure 8 shows the time changes in the analog output of smoke concentration and temperature as seen from the CPU 47 of the receiving control panel 1 in Figure 5. Until the fire alarm level is reached, the analog output Is of smoke concentration, which is highly responsive to fire, is When the smoke density analog output Is reaches the fire alarm level at time t2, only the temperature analog output Is is monitored thereafter.

According to the fire judgment and fire control based on the analog output of smoke concentration and temperature from the detector shown in Figs. Fires can be detected quickly by issuing warnings and fire alarms, while fire extinguishing equipment can be started with high reliability after a fire alarm is issued based on analog output of smoke concentration. Since the activation of the fire extinguisher is controlled based on the analog temperature output, malfunctions due to non-fire alarms can be reliably prevented.

FIG. 9 is a circuit block diagram showing another embodiment of the composite fire detector. This embodiment has a built-in switching function from analog output of smoke concentration to analog output of temperature on the detector side. It is characterized by a single signal line connection between the control panel and the composite fire detector.

In FIG. 9, the power supply section 10 is the same as the embodiment shown in FIG. 1, the smoke detection section 20 from the oscillation circuit 21 to the sample hold circuit 25 is the same as in FIG. 1, and the temperature detection section is the same as in the embodiment shown in FIG. Also, the components from the reference voltage circuit 31 to the amplifier circuit 33 are the same as in the embodiment shown in FIG.

In addition to this, in the embodiment shown in FIG.
A peak cut circuit using ZD1 is provided,
For example, the peak cut level determined by the Zener voltage of the Zener diode ZD1 is set to 7 volts, which corresponds to the fire alarm level. That is, the output voltage obtained from the sample and hold circuit 25 with respect to the smoke concentration has the characteristics shown in FIG. %/m, giving an output characteristic shown by a dashed line that saturates to 7 volts. In this way, the output voltage subjected to a peak cut of 7 volts by the Zener diode ZD1 is given to the current conversion circuit 28 via the impedance conversion section 26, and is relayed with the smoke density output characteristic shown on the left side of FIG. It is output to the signal line l3 to the reception control panel via the contact 72a. At this time, the analog output characteristic of the smoke density is subjected to a peak cut of 7 volts by the Zener diode ZD1, so when the smoke density exceeds 16%/m, the output current Is becomes saturated at 14 mA.

On the other hand, the configuration of the temperature detection section 30 is the same as that in the embodiment shown in FIG.
An analog output switching circuit consisting of a coparator 70 and a relay 72 is provided between the terminals 5 and 5.

That is, the comparator 70 receives the smoke concentration detection voltage Vs from the impedance conversion section 26 in the smoke detection section 20 and the temperature detection voltage Vh from the amplifier circuit 33.
is input, and when the smoke concentration detection voltage Vs is higher than the temperature detection voltage Vh, the output of the comparator 70 becomes L level, making the relay 72 inactive, and closing the relay contact 72a provided at the output of the current conversion circuit 28. On the other hand, the relay contact 72b provided at the output of the current conversion circuit 35 is opened.

Next, the temperature detection voltage is calculated from the smoke concentration detection voltage Vs.
When Vh increases, the output of the comparator 70 switches to H level, activating the relay 72, opening the relay contact 72a and closing the relay contact 72b.

That is, out of the smoke concentration analog output and the temperature analog output from the comparator 70 and the relay 72,
Only the higher one will be selected and sent to the receiving control panel. Furthermore, the analog output of smoke concentration is always suppressed to below the operating level of fire extinguishing equipment through peak cutting by the Zener diode ZD1, so as the fire progresses, the analog output of temperature always exceeds the analog output of smoke concentration, and the fire At the initial stage, an analog output of smoke concentration is sent out, but after the fire alarm level is exceeded, the output is switched to an analog output of temperature.

In other words, the change in the smoke concentration analog output Is' of the composite fire detector in Fig. 9 during a fire exceeds the fire alarm level and reaches the activation level of the fire extinguishing system, etc., as shown by the dotted line in Fig. 7. The cut level saturates to a certain level, and at time t3' when the temperature analog output Ih exceeds the saturated smoke concentration analog level Is', the sensor side switches from the smoke concentration to the temperature analog output.

As a result, the receiving control panel makes fire judgments and fire control based on comparisons with the caution signal level, fire alarm level, and operating level of fire extinguishing equipment, etc., without distinguishing between smoke concentration analog output and temperature analog output. be able to.

Although the above embodiment uses a composite fire detector in which a smoke detector and a temperature detector are included in one fire detector, a heat detector and a smoke detector each having an independent temperature detector may also be used. The same effect can be obtained even if smoke detectors having a fire alarm are installed in locations where the physical conditions associated with a fire are substantially the same.

In addition, in the embodiment of the present invention, when the analog signal from the temperature detection section exceeds the activation level, the fire extinguishing device is activated as the activation device, but it is also possible to activate the external alarm, close the fire door, and open the escape exit at the same time. It may also be possible to determine activation or the like.

Furthermore, the activation control of external alarm activation, fire door closure, and escape exit opening causes less damage than activation of fire extinguishing equipment, so activation control should be performed when the analog signal of the smoke detection unit, which is detected quickly, exceeds the activation level. Good too. In this case, the composite fire detector shown in Figure 9 cannot be used.

(Effects of the Invention) As explained above, according to the present invention, a smoke detection section that outputs an analog signal proportional to the smoke concentration caused by the fire and a temperature sensor that outputs an analog signal proportional to the temperature caused by the fire are provided in the same section. In a fire alarm system that is provided with a detection section and a reception control panel that receives analog signals from the smoke detection section and the temperature detection section via a signal line, at least one of the analog signals of temperature and smoke concentration is provided. A fire judgment means that determines a fire when one of them exceeds a common fire threshold level for temperature and smoke concentration; Since a start control determination means for determining start control of the start device is provided, it is possible to realize fire judgment and fire control that take advantage of both highly responsive smoke concentration and highly reliable fire temperature. can.

In addition, as an effect unique to the present invention, the output characteristics on the sensor side are set so that a common threshold level can be used for the analog output characteristics of temperature and smoke concentration, so the analog output characteristics of temperature and smoke concentration are set at the receiving control panel. There is no need to set different threshold levels for each output, and fire judgment and fire control processing can be simplified.

Furthermore, by providing the sensor side with a circuit function that switches from smoke density analog output to temperature analog output, even when outputting two different analog signals, only one signal line with the receiving control panel is required. In addition, since the analog output can be switched on the sensor side, the burden on the reception control panel can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the composite fire detector used in the present invention, FIG. 2 is an analog current output characteristic diagram of smoke concentration and temperature in the composite fire detector of FIG. 1, and FIG. Figure 3 is a conversion characteristic diagram of smoke concentration and detection voltage in the smoke detection section of Figure 1, Figure 4 is a conversion characteristic diagram of temperature and detection voltage in the temperature detection unit of Figure 1, and Figure 5 is used in the present invention. A block diagram showing an example of the receiving control panel, Fig. 6 is a flowchart showing fire judgment and fire control in the receiving control panel, and Fig. 7 shows temporal changes in each analog output of smoke concentration and temperature during a fire. 8 is a time chart showing the time change of analog output as seen from the reception control panel. FIG. 9 is a circuit block diagram showing another embodiment of the composite fire detector used in the present invention. It is. 1: Receiving control panel, 2a, 2b, 2c: Composite fire detector, 10: Power supply section, 11: Rectifier circuit, 1
2: Noise absorption circuit, 13: Constant voltage circuit, 20: Smoke detection section, 21: Oscillation circuit, 22: Light emitting element, 2
3: Light receiving element, 24: Amplification circuit, 25: Sample and hold circuit, 26: Impedance conversion section, 2
7, 34: operational amplifier, 28, 35: current conversion circuit, 30: temperature detection section, 31: reference voltage circuit, 3
2: Zener type temperature detection element, 33: amplifier circuit,
40: Transformer, 41: Rectifier circuit, 42: Stabilized power supply, 43: Power switch, 44: Input interface, 45: A/D converter, 46, 48, 52:
I/O port, 47: CPU, 49, 53: Output interface, 50: Display, 51: Alarm,
54: Control relay circuit, 55: ROM/RAM,
56: timer, 70: comparator, 72: relay, 72a, 72b: relay contact.

Claims (1)

[Claims] 1. A smoke detection section that outputs an analog signal proportional to the concentration of smoke caused by a fire and a temperature detection section that outputs an analog signal proportional to the temperature caused by the fire are provided in the same monitoring section, and the smoke detection section outputs an analog signal proportional to the temperature caused by the fire. In a fire alarm system equipped with a reception control panel that receives an analog signal from the temperature detection section and the temperature detection section via a signal line, at least one of the temperature and smoke concentration analog signals is common to both temperature and smoke concentration. A fire determination means that determines that there is a fire when the fire threshold level is exceeded; and a fire determination means that determines that there is a fire when the fire threshold level is exceeded; A fire alarm device characterized by comprising: control determination means.