JPS5831038B2 - fire detector - Google Patents

Description

[Detailed description of the invention] This invention is an improved fire detector.

Figure 1 is a circuit diagram of a fire alarm system equipped with a conventional fire detector De.
1 and 12, one of a plurality of sensors connected in parallel with each other is shown.

To explain its operation, when the fire detection element thermistor Th receives the heat of the fire, its resistance value decreases, and the resistance value Th and resistance R decrease.
When the potential Vb at the connection point S to the transistor T1 decreases and becomes lower than the emitter potential Ve of the transistor T1 determined by the resistance values of the resistors R2 and R3, T1 becomes conductive, and the voltage generated across the resistor R4 causes the thyristor T2 to conduct.

As a result, from the positive terminal of the power supply E in the receiver Re, the recovery type Ken Kr, the line 12, the parallel circuit of the operation indicator La and the resistor R5, the line T2, the line diode D4, and the district relay N as a receiving relay. Current flows through to the negative terminal of the power source E, and the relay N operates to close the contacts n1j R2j R3, self-hold by nl, turn on the district indicator light Lf through R2, and through R3 and resistor R1. A lighting current is supplied to the operation indicator light La of the sensor De.

In this case, diode D4 prevents the lines 11, 12 from being shorted by closing nl.

When such a fire detector De is used in a fire alarm system, in the event of a fire, the line 1 is
1. When a current close to a short circuit flows in 12, and the sensors of some other lines (not shown) operate one after another, there is a risk that the capacity of the power supply E in the receiver Re will be insufficient. Also, if one of the detectors connected between lines 11 and 12 is activated, the voltage between ■□ and 12 becomes almost short-circuited, making it impossible for other detectors connected to the same line to detect a fire. was there.

When the present invention is appropriately configured and used in a fire alarm system, the large current flowing through the sensor once activated is immediately maintained in operation after the time required to activate the receiving relay in the receiver. The extremely low value required for
The voltage of the line to which the sensor is connected is quickly restored to the normal voltage from a state close to short circuit, so that even when the sensors of multiple lines operate one after another, the capacity of the power supply in the receiver is insufficient. Even if one sensor on the same line is activated, it is possible for other sensors to detect a fire, and there is no risk of causing a fire when multiple sensors on the same line are activated simultaneously or one after another. The purpose is to obtain a fire detector that can maintain the operation of all activated detectors and maintain the operation of each operation indicator by the operation holding current of each sensor, and the following. The invention will be explained by means of embodiments shown in the drawings.

FIG. 2 is a circuit diagram of an embodiment of the present invention. This fire detector De includes a fire detection circuit 1, a switching circuit 2 which operates according to the output of the circuit 1, and a receiving circuit in the receiver when the circuit 2 operates. circuit 2 for a sufficient time to activate the relay.
A timer circuit 3 for passing a current close to the short-circuit current to the receiving relay through the circuit 3, an operation display circuit 4 forming an oscillation circuit for lighting an operation indicator lamp after the operation of the circuit 3 is completed, and a voltage stabilizing circuit 5. The fire detection circuit 1 and the switching circuit 2 are the same as the corresponding circuits in FIG.
In series, a voltage stabilizing circuit 5 is connected between the lines 11 and 12.

FIG. 4 is a circuit diagram of a receiver Re to which this embodiment is connected via line 11.1.2.

To explain its operation, in the monitoring state, a small monitoring current flows from the line 12 to the resistors R8 and R9 in the circuit 4, the resistor R1 and thermistor Th in the circuit 1, and the resistors R3 and R2.
The current flows through the parallel circuit of R8 and the diode D3 to the line 11, but since it is a very small current, only a small voltage is generated across the series circuit of the resistors R8 and Ro.

Next, when the thermistor Th receives heat from the fire, its resistance value decreases, and the potential vb at point b drops as shown in Figure 3a.When it becomes lower than the emitter potential Ve of the transistor T1, T1 becomes conductive, and the thyristor T2 conducts as shown in Figure 3.

When T2 becomes conductive, a voltage close to the power supply voltage is applied across the timer circuit 3 and the operation display circuit 4, and a charging current of the capacitor C1 flows between the emitter and base of the transistor T3 in the circuit 3 through the resistor R6, and T3 conducts, T
3 and the relay A with low internal resistance for driving the interlocking controller that closes the air conditioning duct in the fire room, instantly charges the capacitor C2 in the circuit 4, and the charging voltage becomes the gate voltage of the N gate thyristor 4. T4 becomes conductive as soon as it exceeds .

T3. The course of conduction of A is shown in FIG. 3C.

When T4 becomes conductive, the line 12 connects T3, A, T4, the light emitting diode D2 as an operation indicator, and the thyristor T2.
A large signal current close to a short circuit current flows through diode D3 and line 11, and this current operates relay A and district relay N as a receiving relay in receiver Re.

When N operates, it performs the first control such as stopping the air conditioner in the fire area, closes the contact n1j R27R3, holds itself by nl, lights the area indicator light Lf through R2, and senses it through R3 and resistor R11. Vessel De
A lighting current is supplied to the operation display circuit 4 of.

In this case, while a large signal current is flowing through the lines 18 and 12, the voltage generated across the resistor R1 causes the transistor T5 to conduct through the load resistor R13, and the voltage generated across the resistor R1'3 causes the counter circuit C to count 1. However, at that time, there is no output from circuit C, transistor T6 is not conductive, and relay B, which performs second control such as the operation of the smoke evacuation equipment, does not operate.

By selecting the resistance value of the resistor R6 to be sufficiently larger than that of the resistor R5, the time t1 during which the transistor T3 in the timer circuit 3 in the sensor De is conductive can be determined by the resistance value of the resistor R5 and the capacitance value of the capacitor CI. A desired value can be selected depending on the time constant.

When the conduction of T3 stops, the N-gate thyristorate 4 of the operation display circuit 4 that forms the oscillation circuit also stops conducting, and the circuit 4 returns to normal operation with a period determined by the time constant determined by the resistance value of the resistor R7 and the capacitance value of the capacitor C2. The light emitting diode D2 starts to oscillate, and thereafter the light emitting diode D2 lights up in a pulsed manner due to the discharge current of the capacitor C2.

The conduction of T4 and the lighting progress of D2 are as shown in FIG. 3d.

Further, when the conduction of T3 stops, the current flowing through the thyristor T2 is switched to the minimum holding current for T2 to maintain itself.

This minimum holding current flows through resistors R8 and R9, and the line voltage applied to the activated sensor De returns to approximately the normal voltage.

Figure 3e shows the temporal change in the line current If flowing through the line 11j'2, and Figure 3f shows the voltage V between the lines 11' and 12.
It shows the temporal change of l.

Next, when another sensor connected to the same line operates, the line voltage Vl drops to a value close to a short circuit for a time t1 immediately after the operation, but due to the discharge current of the capacitor C3 of the voltage stabilizing circuit 5, The minimum holding current of the thyristor T2 of the activated sensor is supplied through resistors R8 and R9.

The operation of this other sensor causes the resistance R1 in the receiver Re to
Due to the voltage generated again at □, the transistor T5 also becomes conductive and the counter circuit C counts 2, but the output of the circuit C at that time causes the transistor T6 to become conductive and the relay B also operates, causing the operation of smoke evacuation equipment, etc. 2 control is performed.

In the circuit shown in FIG. 4, when multiple sensors connected to the same line operate one after another and the time t1 during which the transistor T3 in the timer circuit in each sensor is conductive overlaps, the counter circuit C only counts 1. Therefore, in order to avoid this, connect a series circuit of a capacitor and a resistor in parallel with the resistor R11, and when a large signal current begins to flow through the lines 11 and 12 and when the signal currents begin to overlap, Resistor R11
A pulse voltage obtained by differentiating the voltage change occurring in the resistor may be generated in the resistor, and the voltage generated in the resistor may cause the transistor T5 to conduct.

FIG. 5 is a circuit diagram of another receiver Re used in connection with the embodiment shown in FIG. 2. The difference from the receiver Re shown in FIG. Operate the drive section of the electromagnetic rotary switch F so that the wiper W of the switch section R8 advances one step at a time over contacts 0 to 3, and when W comes into contact with contact 2, perform the second control. The only difference is that a circuit is formed for this purpose.

Even in the circuit shown in FIG. 5, when multiple sensors connected to the same line operate one after another and the time t1 during which the transistor T3 in the timer circuit in each sensor is conductive overlaps,
The wiper W of the switch section R8 of the rotary switch F only goes to contact 1, and the second control is not performed, so in order to avoid this, a relay with a large current is used instead of the resistor R11, and its make contact is connected between wiper W of switch R8 and contact 2, and when only one sensor operates, the relay does not operate and acts as a resistor similar to resistor R1, and multiple sensors The transistor T3 is turned on for a time t1.
It is only necessary to activate the relay when the current flowing through the relay increases and the make contact closes to perform the second control.

FIG. 6 shows the timer circuit 3 and its operation in another embodiment of the present invention when a current nail-shaped operation indicator M is used in place of the light emitting diode D20 in the operation indicator circuit 4 in the fire detector De shown in FIG. This embodiment is completely the same as the embodiment shown in FIG. 2 except for the circuit 4.

The operation display circuit 4 in this embodiment has a resistor R14 connected in series with the current peg type operation indicator M, a display protection diode D8 connected in parallel, and a resistor R14 connected in series with it.
7 is connected, and the connection relationship with the timer circuit 3 is as shown in the figure.

In this embodiment, when the thyristor T2 in the detector De becomes conductive in the event of a fire, the large signal current passing through the transistor T3 and the relay A mainly flows through the diode D8, and the monitoring current and self-maintenance of the thyristor T2 during monitoring. The current flows through resistors R7, R1 and the indicator M, which operates with a portion of the large signal current and self-holds with a self-holding current of T2.

As described above, the fire detector according to the present invention has an appropriate configuration, so that when it is used in a fire alarm system, the large current flowing through the detector once activated can be used to operate the receiving relay in the receiver. The voltage of the line to which the sensor is connected is set to an extremely low value necessary to maintain its operation immediately after a short circuit, and the voltage of the line to which the sensor is connected quickly returns to the almost normal voltage from a state close to a short circuit. Even when sensors operate one after another, there is almost no chance that the large currents flowing through the sensors overlap, eliminating the risk of insufficient power supply capacity in the receiver, and allowing only one sensor on the same line to operate. Even after the fire has been activated, other detectors can detect the fire, and even when multiple detectors on the same line operate at the same time or one after another, the operation of all the activated sensors is maintained, and each There is an effect that the operation of each operation indicator can be maintained by the operation holding current of the device.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a fire alarm system equipped with a conventional fire detector, Fig. 2 is a circuit diagram of an embodiment of the present invention, and Fig. 3 is a time chart showing the operating status of each part of the embodiment. Fourth
5 and 5 are circuit diagrams of two types of receivers to which an embodiment of the present invention is connected, and FIG. 6 is a circuit diagram of a part of another embodiment of the present invention. De... - Fire detector, 1... Fire detection circuit of De, 2... Switching circuit of De,
3...Timer circuit of De, A...Relay in circuit 3 for operating the interlocking controller for each sensor, 4... Operation display circuit of De, 5...
・De voltage stabilizing circuit, Re...Receiver, N・
...Receiving relay during Re, D22M...
・Light-emitting diode and current needle-shaped operation indicator as operation indicators.

Claims (1)

[Scope of Claims] 1. Detecting phenomena such as heat, smoke, gas, light, etc. caused by a fire, operating a switching circuit, and short-circuiting for a time sufficient to operate a receiving relay in a receiver through a timer circuit. A current close to the current is passed through the receiving relay, and thereafter the above-mentioned switching circuit switches to a small holding current necessary to maintain operation, and multiple fire detectors connected in parallel are Equipped with a voltage stabilizing circuit on the output side to maintain the holding current of all activated fire detectors even when activated simultaneously or one after another, and the operation indicator is operated by the above-mentioned holding current supplied from the receiver. A fire detector characterized in that: 2. An operation indicator lamp is used as an operation indicator, and its lighting is performed in a pulsed manner by the pulse current generated by the oscillation circuit that operates when the current in the switching circuit is switched from a current close to the short-circuit current to a slight holding current. A fire detector according to claim 1. 3. Claim 1, in which a timer circuit is provided with a relay for operating an interlocking controller for each sensor, and the relay is operated by a current flowing through the timer circuit.
Fire detector as described in section.