JPS6022475Y2 - fire alarm - Google Patents

Description

[Detailed explanation of the idea] This invention relates to fire alarms.

Detection wires including thermocouples in fire alarms must be periodically checked for disconnection in case of a fire.

For this reason, a dedicated portable disconnection check tester has conventionally been prepared, but it is troublesome to go to the location where the fire detector is installed and perform the test.

On the other hand, there were devices that had a detection operation that detected fire and disconnection (for example, Japanese Patent Application Laid-Open No. 52-1628
However, since cascade connections cannot be made, the amount of wiring increases and the work becomes complicated.

Therefore, the purpose of this invention is to provide a fire alarm system that does not require going to the installation site to conduct a disconnection test, and can reduce the amount of wiring and simplify the work.

An embodiment of this invention is shown in FIGS. 1 to 3.

That is, the differential distribution type fire alarm of this embodiment is composed of a receiver 1, a large number of sensors 2, and a cordon 4 in which the sensors 2 are connected in cascade and a terminating resistor 3 is connected.

In this case, the receiver 1 performs a fire alarm operation when the cordon 4 is short-circuited, and also performs a disconnection alarm operation when the cordon 4 is opened, that is, the resistance is infinite.

In addition, as shown in FIG. 2, each sensor 2 connects a disconnection detection circuit 6 incorporating a relay and a fire detection circuit 7 incorporating a relay to a sensing wire 5 including a thermocouple, and The B contact (normally closed) 8 (constituting a normally closed switch) of the relay in circuit 6 is connected in series mode, and the A contact (normally open) 9 (constituting a normally open switch) of the relay in fire detection circuit 7 is configured in parallel mode. A four-terminal circuit is constructed by the terminals 15a to 15b so that the terminals 15a and 15b on the side closer to the b contact 8 are used as output ends, and the terminals 15c and 15d on the opposite side are used as input ends.
The four-terminal circuits of each sensor 2 are connected in cascade via a cordon 4, one output end of which is connected to the input end of the receiver 1, and a terminating resistor 3 is connected to the other input end. Connected.

Figure 3 shows its detailed diagram.

That is, the disconnection and fire detection circuits 6 and 7 are non-inverting connection circuits using operational amplifiers (OP amplifiers).

In this circuit, 10 is the operational amplifier of the fire detection circuit 7;
1 is an operational amplifier of the disconnection detection circuit 6; 12. ．． 12' is a reverse current blocking diode connected to the output side of the operational amplifier 10.11, 13.13' is a relay for shorting or opening the cordon 4 connected to this reverse current blocking diode, and R1-R4 are operational amplifiers. 10.11 is an input terminal voltage setting resistor, and 14 is a Zener diode.

Now, if a fire occurs, a displaced voltage will appear at the positive input terminal of the operational amplifier 10.11 due to the thermoelectromotive force generated in the thermocouple, but the reference level of the negative input terminal will be determined by the calculation of the fire detection circuit 7. Since the amplifier 10 has a lower electromotive force of the resistor R3 than the operational amplifier 11 of the disconnection detection circuit 6, when this voltage reaches the fire detection voltage, only the operational amplifier 10 operates to operate the relay 13.

Therefore, the a contact 9 of the cordon 4 is closed, the cord 4 is short-circuited, and the receiver 1 performs a fire alarm operation.

In addition, if the sensing wire 5 including the thermocouple is disconnected, the sensing wire 5
The voltage applied from the cordon 4 appears at the terminal as a disconnection voltage.

For this reason, the fire detection circuit 7 and the disconnection detection circuit 6 are operated simultaneously.

Therefore, the a contact 9 of the relay 13 and the relay 13'
However, since the B contact 8 is connected in series to the cordon 4 on the side closer to the receiver 1 than the A contact 9, it is not possible to indicate the open state of the cordon 4 to the receiver 1. Therefore, the receiver 1 performs a disconnection notification operation.

In addition, in this invention, the disconnection detection circuit 6 drives the normally open switch, the fire detection circuit 7 drives the normally closed switch,
Furthermore, the receiver 1 can be configured to perform a disconnection alarm operation when a short circuit occurs, and a fire alarm operation when an open circuit occurs.

Furthermore, in the embodiment described above, the B contact 8 is provided closer to the receiver 1 than the A contact 9, but this is because the detection circuits 6 and 7 operate at the same time when the wire is disconnected. It is not limited to.

As described above, the fire alarm of this invention connects a normally closed switch in series to the detection circuit that detects fire and disconnection of the sensing wire, which turns off when one of the switches operates, and turns it on when the other operates. A west terminal circuit is provided that connects the normally open switches in parallel, and the four terminal circuits of each detection circuit are connected in cascade, one end of which is connected to the receiver, and the other end is connected to the terminal impedance. Since the structure is such that the input terminal performs the receiving operation in the short-circuited state and in the open-circuited state, the following effects can be obtained.

In other words, there is no need to go out and conduct periodic tests to check for disconnections as in the past, and because the detection circuits are connected in cascade, the amount of wiring from the receiver is reduced compared to the past, making wiring work easier. Become.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of this invention, FIG. 2 is a block diagram of its main parts, and FIG. 3 is a detailed circuit diagram thereof. 1... Receiver, 2... Sensor detection circuit, 4... Security line, 5... Sensing line including thermocouple, 6... ...Disconnection detection circuit, 7...
Fire detection circuit, B contact normally closed switch, 9
・・・・・・A contact normally open switch, 10.11...
...Operation amplifier, 13.13'...Relay 1
5a to 15d...terminals (four-terminal circuit).

Claims (1)

[Scope of utility model registration request] A plurality of sensing wires, each including a thermocouple, and a normally open switch connected to each of these sensing wires to perform fire detection and disconnection detection, and which are turned on when one of them is activated, are arranged in parallel, and the other is connected to the sensing wires. A detection operation has a four-terminal circuit made up of normally closed switches connected in series that turn off when the operation of and a receiver for performing the above-mentioned detection operations, the four-terminal circuits for each of the detection operations are connected in cascade, one end of which is connected to the input end of the receiver, and the other end is connected to a terminal impedance. Machine.