JPS597229A - Detector of temperature - Google Patents

Abstract

PURPOSE:To find easily disconnection under conditions of very low temperature of atmosphere to be detected, by providing a resistor in parallel with a thermistor. CONSTITUTION:When a detector 1 is placed in an atmosphere such as a fluid whose temperature is to be determined, the temperature of a thermistor 1e becomes equal to the temperature of the ambient atmosphere in a steady state. The current which flows from an electric source 2c having a constant voltage Vc through a resistor 2, terminals 1i and 1j, a distribution line 1c, the thermistor 1e and a resistor 1f, becomes a function of change in the temperature of the thermistor 1e. When the voltage at the terminal 1j is determined with respect to the change in temperature, the voltage is expressed as a function of the temperature.

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a temperature sensor.

ill come, 7. A thermistor, which is mainly used for detecting humidity, has a superimposed resistance value that increases rapidly when the ambient humidity becomes extremely low.

Under such temperature conditions, when temperature is measured using one of the → no misters, the resistance value becomes larger than the other, so the voltage measured between the → boomister during temperature measurement is equal to the power supply voltage. The values are close. As a result, if the wire connecting the thermistor and the measuring device breaks during the measurement, is it because the thermistor itself has increased its resistance value, or is it due to a break in the wire? However, it has the drawback that it cannot be easily determined.

An object of the present invention is to make it possible to easily detect the disconnection even if the disconnection occurs in the low-temperature state described above. The objective is to provide a crystallinity detector to I.

To explain the present invention based on an embodiment, FIG. 1 shows an electrical circuit diagram of an embodiment of a temperature detector according to the present invention.

In FIG. 1, 1 is a temperature detector, 1e is a thermistor, 1f and 2 are resistors, 11, li 1,
1m and 4b are terminals, 2C and 4a are constant voltage power supplies, 3 is a current amplifier, 4 is a comparator, 1 shown by a solid line
a, 1b, lc, ld, 2az 2b and 3a are electric wires, and 5 is a ground.

Further, the detector 1 in FIG. 1 has a configuration as shown in FIG. 2, and FIG. 2 shows a determination and a side view of the detector 1.

In Fig. 2, the same reference numerals as in Fig. 1 indicate the same materials as in Fig. 1.
A resistor 1f is buried between the electric wire IC and the thermistor 1e, and the thermistor 1e and the resistor 1f are made of resin 1h having electrical insulation resistance.
It is integrally fixed to the housing 1g.

To explain the operation in the configurations shown in Figs. 1 and 2 above, when the detector 1 is placed in an atmosphere containing a fluid whose temperature is to be measured, at a steady state 'Af, qq', at j5,
→Boomista 1e is in the surrounding atmosphere, 'j,,j
)! It is equal to L and becomes 2, and tlj in Mr. 1e
The resistance R generally has a characteristic that changes with respect to the temperature T as shown in FIG.

As a result, the resistor 2 is connected to the power supply 2c having a constant voltage VC.
, terminals 11 and 1j, wiring lc.

→The current 1 flowing through the nomister 1e and the resistor 1f becomes a function of the temperature change of the thermistor 1e, and when the voltage at the terminal 1j is measured with respect to this temperature change, the voltage becomes a function of the temperature. The features of the function will be explained below.

Conventional temperature detectors using thermistors are
The resistor 1f in the figure was not present, and the detector 1 was only the 2-mister 1e.

In such a conventional configuration, when the voltage V across the terminal 1.1f is measured, the voltage V is V = Vc/ ((R2/Re) + 1)
・ ・ ・ (1) becomes.

However, VC is the voltage of the power supply 2c, and R2 and Re are the resistance values of the resistor 2 and thermistor 1e.

As is clear from the first equation, the temperature of the ambient air at the thermistor 1e becomes lower, and the resistance value R of the thermistor 1e
When e becomes extremely large as shown in FIG. 3, R2/Re in the third equation becomes close to zero, and the voltage V and the power supply voltage Vc end up having almost the same value.

This means that when the temperatures of the ambient air to be measured are similar, whether V and VC are equal depending on the temperature, or whether the electric wire 1a between terminals 111 and 1a is
Or, it will not be possible to determine whether the electric wire 1b, which is connected to the terminal 1 and is open for 1 m, is disconnected.

Therefore, in order to eliminate the above-described drawbacks of the prior art, the present invention adopts a configuration in which a resistor 1f is provided in parallel with the thermistor 1e, as shown in FIG.

In this way, the configuration of the detector 1 is changed to 1[3 parallel circuits consisting of the IT antibody of thermistor 1e and the resistor 1f, and 1=+
When Yasari and 4-, the voltage at terminal 1j is v = Vc / ((R2/R) -4-l)
(,2) 1-Dashi R=Rf/(++(Rf/Re)) (3). l is the resistance value of resistor 1f, [+, i is the resistance value of resistor 1f,
1 (is the combined resistance value of the thermistor 1e and resistor 1f in FIG. 1).

As shown in FIG. 3, if the resistance value Re of the thermistor 1e becomes extremely large at a temperature of 1, then (R
f/Re) becomes close to zero, resulting in a value close to R+, iRf in equation (3).

Substituting this R2Rf into equation (,2), the voltage V becomes V
c/' (Rf + 1), which is always a similar value to the power supply voltage VC.

In this way, as shown in FIG. 1, (Rf/Re)
, R2 and Rf are set as normal, the voltage V at the terminal 1jl in the case where the fume ambient temperature is low as described above is obviously a value that is different from the voltage VC of the power supply 74-1. Therefore, it is possible to discover that the electric wires 1a and 1b are normal even if the electric wires 1a and 1b are normal.

The parallel circuit of the thermistor 1e and the resistor 1f is integrally enclosed in the housing 1g, and is protected from being disconnected by external force, etc., and is further protected by an electric insulating resistor. Since the parallel circuit is integrally fixed by resin having resistance, the probability of the parallel circuit being disconnected is extremely low.

Furthermore, the present invention uses the comparator 4 to determine whether the electric wire 1a or 1b
If the wire is disconnected, an alarm can be issued immediately. The alarm mechanism will be explained below.

In equations (2) and (3), when the temperature characteristic R3 (Fig. 3) of the thermistor 1e is substituted for Re, and the voltage V resulting from the substitution is expressed with respect to the ambient air temperature T, as shown in Fig. 4. It becomes like characteristic a.

Here, in FIG. 4, Vc1. tJ', Up 2
c ノIJi.

4, where Vb is the voltage at the power supply 4a.
As is clear from the characteristic a in the figure, terminal 1 in Figure 1
The voltage V1 at j and q2 are always lower than the voltages VC and vb as long as the circuit power is maintained.

In contrast to characteristic 6 in FIG. 4, in FIG. 1, the voltage V at the terminal 1j is amplified by the current amplifier 3f;
I have compared it with b.

In this comparison, the comparator 4 is configured not to output power to the terminal 4b as long as the voltage 2 at the terminal 1j is lower than the voltage Vb.

This means that the voltage at terminal 1.1 at A3 in FIG. 4 operates normally according to characteristic a.

On the other hand, if the electric wire 1a or 1b is disconnected,
Since the voltage V applied to the terminal 1j is equal to the voltage of the power supply 2C, the voltage V in the comparator 4 is larger than the voltage vb.

In this way, when V is Vb stiff (when the voltage is low, the comparator 4 outputs power to the terminal 4b, and the alarm (not shown) connected to the terminal 4b is activated), and the disconnection is detected. Let me know what's happening.

In the above case, the terminal 4b is not connected to the alarm, and the power output to the terminal 4b is used as a safety circuit that uses the power to interrupt the necessary 10 routes.As is clear from the above description, the present invention The temperature detector is equipped with a resistor 1f in parallel with the thermistor 1e, so that it can be easily detected even if the wire 1a or 1b breaks when the ambient temperature to be detected is very low. It is something that can be discovered. As a result, we replaced the electric wires 1a and 1b to prevent the disconnection of the electric wires.
・It becomes possible to eliminate troublesome troubles.

Furthermore, when the parallel circuit of the thermistor 1e and resistor 1f is integrally protected within the housing 1g, or when the parallel circuit is protected with resin within the housing 1g, this portion C3 must be protected outside the housing 1g. Even if such factors are added, the probability that the parallel circuit will be disconnected is extremely low.

History 12. When the temperature detector according to the present invention is provided with a comparator 4 that compares the voltage V at the terminal 1.1 with the reference voltage Vb, the temperature sensor immediately knows that the circuit of the electric wire 1a or 1b is disconnected and detects this. This has the advantage of being able to deal with the

[Brief explanation of drawings]

FIG. 1 shows an electric circuit diagram of a temperature detector as an embodiment of the present invention, FIG. 2 shows a side sectional view of the detector 1 in FIG. 1, and FIG. , for the ambient temperature T of the thermistor 1Q in FIG. The negative resistance characteristics are shown, and FIG. 4 shows the characteristics of the voltage V at the terminal 1j in FIG. 1 with respect to the above temperature. The symbols used in the examples are as follows: 1; Detectors la, lb, lc and Uld: electric wire, 1e: thermistor, 1f: resistor, 1g: housing,
1h: resin, 1j51j, lk and 1m: terminal. 2: Resistors 2a and 2b: Electric wire, 2c: Power supply. 3: Current amplifier 3a: Electric wire. 4: Comparator 4a: Power supply, 4b: Terminal. 5: Earth Re: resistance value, V: voltage, T: temperature Patent applicant
Sanwa Seiki Co., Ltd. Representative Etsushi Nishikai 1b Figure 1 Figure 2 19 Figure 4

Claims (1)

[Claims] 1.7 A resistor (1f) is connected in parallel to the thermistor (1e) serving as a temperature detector to form a parallel circuit, and another resistor (2) is connected in series to the parallel circuit to form a parallel circuit. By connecting the circuit and the other resistor in series, connecting a constant voltage power source across it, and measuring the voltage (V) at the open connection between the parallel circuit and the other resistor,
A temperature detector characterized in that the temperature detector is configured to be able to measure ambient temperature at the temperature detector. 2. The temperature sensor according to claim 1, wherein the thermistor (1e) and the resistor (1f) are enclosed in the same housing (1g). 3. The thermistor (1e) and the resistor (if) are made of a resin having insulation resistance (2) in the same housing (1g). Temperature detector as described in item 1 within the range of 5.4. Connect the thermistor (le)!' and resistor (1f) in parallel to form a parallel circuit. resistors (2) are connected in series, and the parallel circuit and the other resistor are connected in series (both ends are connected to a constant voltage power supply, and the parallel circuit and the other resistor are connected to each other). The electric wire (1a) is provided with a comparison circuit (
4) A temperature detector characterized by comprising: 5. The thermistor (1e) and the resistor (1f) are integrally fixed in the same housing (1g) with a resin having insulation resistance. Temperature detector according to item 4.