JPS5922998B2 - Differential distributed sensor - Google Patents

Description

[Detailed description of the invention] This invention relates to a differential distributed sensor.

Conventional thermocouple differential distribution sensors can only have differential characteristics because they detect abnormalities in the sensing wire using a meter relay.

That is, it can be detected when the rate of temperature change in the airflow exceeds a certain value, but it cannot be detected when the temperature of the airflow increases slowly, no matter how high the temperature becomes.

Therefore, in order to detect a slow temperature rise, it becomes necessary to separately provide a fixed temperature spot type sensor, which poses problems in that wiring is laborious and expensive.

Therefore, an object of the present invention is to provide a simple and inexpensive differential distribution type sensor that can detect the rate of change in temperature of an airflow and the temperature of the airflow.

A first embodiment of the invention is shown in FIGS. 1 to 3.

That is, as shown in FIG. 1, this thermocouple type differential distribution type sensor has a predetermined temperature (for example, 70° C.) in the middle of a sensing wire I in which a large number of thermocouple sections 1 are connected by a copper wire section 2. One or more normally-closed thermoswitches 3, which become open when It is.

This detector (2) is composed of a resistance value increase detection circuit 8, a filter circuit 9, a DC amplifier circuit 10, a threshold value detection circuit 11, a switch circuit 12, and a power supply circuit 13.

In this case, the resistance increase detection circuit 8 connects the positive power supply (
+12V) 8b is connected, and the negative input terminal γ is grounded.

Further, the filter circuit 9 is composed of resistors 9at9b, 9c and capacitors 9a, 9e, l.

Furthermore, as shown in FIG. 3, the normally closed thermoswitch (temperature sensitive resistor) 3 has a bimetal 3c to which a movable contact 3a is fixed and a lead wire 3b connected, and a fixed contact 3.
Fix d and lead? A conductor 3f connected to IIJ3e is enclosed in a case 3g, and when the temperature rises, the bimetal 3c bends and the movable contact 3a separates from the fixed contact 3d.

Next, regarding the operation of this thermocouple type differential distribution sensor, (3) when the rate of temperature rise of the airflow is above a predetermined value, (
B) the case where the temperature of the airflow is higher than a predetermined value, and (C) the case where the sensing wire 1 is broken in the middle will be explained separately.

When the rate of temperature rise of the airflow is above a predetermined value: The electromotive force of the thermocouple unit 1, which is proportional to the rate of temperature rise of the airflow, is amplified by the DC amplifier circuit 10 via the resistance value increase detection circuit 8 and the filter circuit 9. , the electromotive voltage of the thermocouple section 1 is a predetermined value (1 m
V), the threshold detection circuit 11 outputs an output signal, which activates the switch circuit 12.
The output signal of this switch circuit 12 is sent to output terminals 14 and 15.
from there to the receiver (g-information device).

In this case, since the resistance value of the sensing line (■) is small (100Ω or less at most), the voltage applied by the resistance increase detection circuit 8 is very small (12V is changed to 22MΩ and 100Ω
The voltage divided by is approximately 0.05 mV), which is negligible.

(B) When the temperature of the airflow is above a predetermined value: When the temperature of the airflow is above a predetermined value (70°C), the normally closed thermoswitch 3 opens and the electromotive voltage of the thermocouple section 1 is applied to the DC amplifier 10. However, the positive power supply 8 of the resistance value increase detection circuit 8
A voltage (50 mV) obtained by dividing the voltage b (dimension 12 V) by the high resistance (22 MΩ) 8a and the input impedance (100 KΩ) of the DC amplifier 10 is applied to the DC amplifier 10,
The threshold detection circuit 11 and the switch circuit 12 operate in the same way as in the case of a prisoner.

(C) When the sensing wire I is disconnected midway: In this case, the operation is exactly the same as in item (B).

As a result of this configuration, it is possible to detect when the temperature rise rate of the airflow exceeds a predetermined value, it can also be detected when the airflow temperature exceeds a predetermined value, and it is also possible to detect a disconnection of the sensing wire I. can.

In addition, by simply adding the thermoswitch 3 and the resistance value increase detection circuit 8 to the configuration that detects when the rate of temperature rise of the airflow exceeds a predetermined value, it can be detected when the airflow temperature exceeds a predetermined value. can be detected, so it is cheaper and requires less construction work than installing a differential distribution type sensor and a constant temperature spot type sensor separately.

In addition, by simply inserting and connecting the thermoswitch 3 to the sensing wire I, existing conventional sensing wires can be used, and installation work is also unnecessary.
It's easy.

Moreover, disconnection of the sensing line I can also be detected, and the reliability of heat sensing can be improved.

Furthermore, unlike a meter relay, the detector (■) is made of a semiconductor, so there are fewer failures.

Next, a second embodiment of the present invention will be described with reference to FIG. 41.

As shown in Figure 4, this thermocouple type differential distribution type sensor uses an abrupt action type positive temperature coefficient thermistor whose resistance value increases rapidly (quasi-disconnection state) when a predetermined temperature T1 is exceeded, as shown in Figure 4. Other than that, the configuration and operation and effects are the same as in the previous embodiment.

Next, a third embodiment of the invention will be described.

In the third embodiment, a slow-action stop thermistor whose resistance value changes slowly is used in place of the rapid-action stop thermistor of the second embodiment.

: This third embodiment has different effects from the first and second ones.

That is, the detection sensitivity of the temperature increase rate of the airflow can be changed depending on the ambient temperature.

To explain in detail, when the ambient temperature is low, it is activated only when the temperature of the airflow is rising rapidly, and when the ambient temperature is high, it is activated even when the temperature of the airflow is rising relatively slowly. .

Moreover, when the temperature exceeds a predetermined temperature, the resistance value increase detection circuit 8
can be operated.

As described above, the differential distribution type sensor of the first invention is
A low-impedance differential distributed sensing wire consisting of multiple thermocouples connected in series with conductive wires, and a temperature-sensitive resistor that is inserted in the middle of this differential distributed sensing wire and increases its resistance value rapidly when a predetermined temperature is exceeded. a resistance value increase detection circuit that applies a voltage to the voltage detection end of the differential distribution sensing line via a resistor having a high resistance value; Since it is equipped with a threshold detection circuit that generates an output when the temperature of the airflow exceeds a predetermined value, it can be detected when the rate of change in the temperature of the airflow exceeds a predetermined value. It is possible to detect when the voltage exceeds the current level, and also to detect disconnection of the sensing wire.In addition, a temperature sensitive resistor is inserted and connected to the conventional differential distributed sensing wire, and a resistor is connected to the voltage detection end of the sensing wire. The above two types of temperature detection and disconnection detection can be performed with a simple additional configuration of simply applying voltage through the sensor, which is cheaper and easier to construct than installing a separate temperature-controlled spot sensor.

Next, the second invention uses a slow-acting positive temperature coefficient thermistor in place of the temperature-sensitive resistor in the first invention, so the sensitivity of the differential detection can be changed depending on the temperature of the airflow. The heat sensing characteristics in the event of a fire outbreak are more suitable than those of the first invention.

[Brief explanation of drawings]

1 to 3 are a block diagram, a circuit diagram of a main part, and a sectional view of a main part, respectively, of a first embodiment of the invention, and FIG. 4 is an explanatory diagram of a second embodiment of the invention. 1...Thermocouple part, 2...Copper wire part, 3.
...Normally closed thermoswitch, 8...Resistance increase detection circuit, 8b...Positive power supply, 8a...
...High resistance, 9...Filter circuit, 10...
. . . DC amplifier circuit, 11 . . . Threshold detection circuit, 12 . . . Switch circuit.

Claims (1)

[Claims] 1. A low-impedance differential distributed sensing wire in which a large number of thermocouples are connected in series using conductive wires, and a resistance that is inserted in the middle of this differential distributed sensing wire when a predetermined temperature is exceeded. a temperature sensitive resistor that increases the value rapidly; a resistance value increase detection circuit that applies a voltage to the voltage detection end of the differential distribution sensing line via a resistor having a high resistance value; A differential distribution type sensor equipped with a threshold detection circuit that generates an output when the voltage generated at the voltage detection terminal exceeds a predetermined value. 2. The differential distribution type sensor according to claim 1, wherein the temperature sensitive resistor is a thermoswitch that opens a contact when a predetermined temperature is exceeded. 3. The differential distribution type sensor according to claim 1, wherein the temperature sensitive resistor is an abrupt action type positive temperature coefficient thermistor whose resistance value increases rapidly when the temperature exceeds a predetermined temperature. 4. A low-impedance differential distributed sensing line in which many thermocouples are connected in series using conductive wires, and a slow operation that is inserted in the middle of this differential distributed sensing line to slowly increase the resistance value as the temperature rises. a positive temperature coefficient thermistor, a resistance value increase detection circuit that applies a voltage to a voltage detection end of the differential distribution sensing line via a resistor having a high resistance value, and a voltage output terminal of the differential distribution sensing line. A differential distributed sensor includes a threshold detection circuit that generates an output when the voltage generated at the voltage exceeds a predetermined value.