JP3159616B2 - Temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detector using a thermocouple.

[0002]

2. Description of the Related Art Conventionally, for example, in an aircraft equipped with a jet engine, engine control such as adjusting the amount of fuel supplied to the engine in accordance with the exhaust temperature of the engine has been performed. In such engine control, a temperature detecting device having a thermocouple is generally used to measure the exhaust gas temperature of the engine.

[0003] A thermocouple joins two types of metal pieces to each other at a temperature measuring end (one end), and generates a thermoelectromotive force (hereinafter, referred to as a temperature measuring junction) corresponding to the environmental temperature of a space where the junction is located. (Several mV to several tens mV) is generated between the reference contact (the other end) of each metal piece. When the temperature measuring contact of the thermocouple is arranged in the exhaust path of the engine, a thermoelectromotive force corresponding to the exhaust temperature of the engine is generated between the reference contacts. Normally, in a thermocouple used for a detection device of the exhaust temperature of a jet engine, one metal piece is a chromel composed of chromium and nickel, and the other metal piece is an alumel composed of aluminum or the like and nickel. I do.

In a temperature detecting device for measuring the exhaust temperature of an engine, a temperature measuring contact of a thermocouple is disposed in an exhaust path of the engine, and a thermoelectromotive force generated by the thermocouple is transmitted to the engine via a voltage transmission path. It is configured to transmit to the control device and instruments in the cockpit. Since the thermoelectromotive force generated by the thermocouple is as extremely low as several mV to several tens mV, the voltage transmission path for transmitting the thermoelectromotive force is continuous (continuous) so that even a minute voltage can be transmitted accurately. It is desirable that the signal line be composed of a pair of signal lines.

However, if the voltage transmission path is constituted by a pair of continuous signal lines, for example, if a part of the voltage transmission path is damaged, it is necessary to replace the entire voltage transmission path. Normally, the voltage transmission path is covered with a hard member, is clamped together with the hard member at a predetermined pitch, and is screwed to the fuselage. Therefore, in the above replacement work, all screws for fixing the damaged voltage transmission path are removed. After removing this path, a new voltage transmission path needs to be laid and screwed.

In addition, since a large number of signal lines and devices are provided inside the aircraft in addition to the above-described voltage transmission paths, it is necessary to perform the above-mentioned replacement work without affecting these. That is, for maintenance work such as replacement work,
It is extremely troublesome. For this reason, conventionally, the voltage transmission path is configured by connecting a plurality of connectors of a predetermined length of harness having a pair of signal lines.

Here, the connector 1 for connecting each of the harnesses constituting the voltage transmission path will be described with reference to FIG. FIG. 4 is a structural view showing the connector 1 with a part cut away. The connector 1 shown in FIG.
A harness having a cable 2a comprising ₁ and 2a ₂ ;
It connects a harness having a cable 2b composed of a pair of signal lines 2b ₁ and 2b ₂ . In this drawing, the outer shell (made of a hard member) of each harness is not shown.

As shown in FIG. 1, a connector 1 includes a pair of contact sockets (hereinafter abbreviated as sockets) 3
It comprises a female connector 4a provided with a ₁ and 3a ₂ and a male connector 4b provided with contact pins (hereinafter abbreviated as pins) 3b ₁ and 3b ₂ . Female connector 4
a is attached to the end of the harness having the cable 2a so that the signal lines 2a ₁ and 2a ₂ of the cable 2a and the sockets 3a ₁ and 3a ₂ conduct. Similarly, the male connector 4b is connected to the signal lines 2b ₁ and 2b _{2 of the} cable 2b.
2b so that the pins 3b ₁ and 3b ₂ are electrically connected to each other.
Attached to the end of the harness.

Further, the female connector 4a and the male connector 4
b, a screw thread and a screw groove are formed so as to be screwed to each other.
a ₁ , 3a ₂ and the pins 3b ₁ , 3b ₂ are fitted. That is, each socket 3a _1, 3a ₂ and the pin 3b
_1, 3b ₂ via the respective signal lines 2a ₁ of the cable 2a,
2a ₂ and the signal lines 2b ₁ and 2b _{2 of the} cable 2b are configured to conduct. The conventional temperature detecting device has the above-described configuration.

[0010]

A jet engine such as an aircraft vibrates surrounding members violently during operation. This vibration is propagated through a thermocouple provided in an exhaust path of the engine and a harness connected to the thermocouple. Each of the harnesses constituting the voltage transmission path of the temperature detection device is clamped at a predetermined distance interval, so that the vibration transmitted through each of the harnesses can be attenuated to some extent. It cannot be avoided that 1 vibrates.

The connector 1 is formed by screwing a female connector 4a and a male connector 4b, but they are not completely fixed. Therefore, when the vibration is transmitted to the connector 1, the female connector 4a and the male connector 4b vibrate individually (without synchronization). That is, for example, a socket 3a ₁ and pin 3b ₁ is relatively motion at a cycle corresponding to the frequency of both. Socket 3a ₂ and pin 3b ₂
The same applies to.

Further, while the jet engine is operating, the frequency (frequency) of the vibration transmitted from the engine to the connector 1 is in a wide range of about 100 to 2000 Hz, and the acceleration applied to the connector 1 also reaches about 20 G. There is also. In such an environment, the socket 3a ₁ and pin 3b _1, socket 3a ₂ and the pin 3b ₂ and, respectively, resulting in severely worn at the contact surfaces. The abrasion powder generated thereby adheres to the surfaces of the sockets 3a ₁ , 3a ₂ and the pins 3b ₁ , 3b ₂ , and eventually corrodes to cause poor contact of the connector 1. That is, in the conventional temperature detecting device, it is not often the case that the exhaust temperature of the engine cannot be accurately detected due to the occurrence of the contact failure in the connector 1.

Particularly, in an aircraft in flight, if the exhaust temperature of the engine cannot be detected accurately, a serious problem occurs in that the engine must be operated in an emergency manner. There is a long-awaited need for a temperature detection device capable of stably and accurately detecting a temperature. The present invention has been made in view of the above circumstances, and has as its object to provide a temperature detection device capable of stably and accurately detecting the temperature of an object to be measured.

[0014]

According to a first aspect of the present invention, there is provided a temperature detecting device, wherein a thermocouple for generating a thermoelectromotive force in accordance with an environmental temperature of a temperature measuring contact is provided, and a thermocouple is provided in an oscillating environment. And a voltage transmission path for transmitting the generated thermoelectromotive force to the next-stage device.The voltage transmission path is configured by connecting a plurality of harnesses with connectors, and the harness is connected to each metal piece constituting the thermocouple. In a temperature detection device having a pair of signal lines made of the same kind of metal material, a connection terminal constituting a connector for connecting between the respective harnesses is different from the metal piece, and is more ductile than the metal piece, and has an electrical conductivity. The coating is characterized by being covered with a plating layer made of a metal material having a ratio greater than a predetermined value.

The temperature detecting device according to a second aspect is characterized in that, in the first aspect, the metal material is gold. Further, a temperature detecting device according to a third aspect is the temperature detecting device according to the first aspect, wherein the metal material is platinum. According to a fourth aspect of the present invention, there is provided the temperature detecting device according to the first aspect, wherein an environmental temperature distribution around the voltage transmission path is substantially uniform and heat generated between the connection terminal and the plating layer. The metal material is selected so that the electromotive force is negligible in the entire voltage transmission path. Furthermore, the temperature detecting device according to claim 5 is different from the temperature detecting device according to claim 1 in that the environmental temperature distribution around the voltage transmission path is substantially uniform, and the connection terminal and the plating layer are arranged. This is characterized in that the thermoelectric generator is used in an environment in which the thermoelectromotive force generated between the above and the entire voltage transmission path is negligible.

[0016]

In the temperature detecting device according to the first aspect, since the voltage transmission path formed by connecting a plurality of harnesses to the connector is disposed in the vibration environment, each connection terminal is provided for each of the harness units. Vibrates independently. In the state where the connectors are connected, each connection terminal is in contact with the corresponding connection terminal. Therefore, when each of the connected connection terminals vibrates independently, the vector of the force applied (received) to each other becomes different. It fluctuates based on the frequency (frequency) of the connection terminal.

The change in the force vector is transmitted to the plating layer of each connection terminal. Since the plating layer is made of a metal material having excellent ductility, it is deformed in accordance with the applied force vector. That is, the vibration is absorbed. In addition, since the metal material is excellent in electric conductivity, the rate of reduction of the voltage transmitted through the voltage transmission path is smaller than when no plating layer is provided.

Further, in the temperature detecting device according to the second aspect, as the metal material, gold having extremely excellent electric conductivity and ductility is used. As the material, platinum excellent in electric conductivity, ductility, and heat resistance is used.

Further, in the temperature detecting device according to the fourth aspect, the metal material is such that a thermoelectromotive force generated between the connection terminal itself and a plating layer made of the metal material is ignored as a whole of the voltage transmission path. It is selected to be as large as possible. According to a fifth aspect of the present invention, in the temperature detecting apparatus according to any one of the first to third aspects, the environmental temperature distribution around the voltage transmission path is substantially uniform, and the connection terminal and the plating are provided. It is used in an environment where the thermoelectromotive force generated between the layers is negligible as a whole in the voltage transmission path.

[0020]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of a control system including the temperature detecting device 5 according to one embodiment of the present invention. The temperature detecting device 5 shown in FIG. 1 outputs an average voltage (described later) according to the exhaust gas temperature of a jet engine (hereinafter, referred to as an engine 6) such as an aircraft.

In FIG. 1, reference numeral 7 denotes an engine control unit, which controls the engine 6 based on various signals transmitted from a control unit (not shown), the temperature detection device 5, and the like. Also,
8 is a temperature monitoring device installed in a cockpit or the like,
The exhaust temperature of the engine 6 represented by the average voltage transmitted from the temperature detecting device 5 is transmitted to the operator. The above-described temperature detecting device 5 includes a thermocouple 9, a temperature measuring circuit 10, and the like, which will be described later.

As shown in a partial cross-sectional view of FIG. 3, the thermocouple 9 has a pair of metal pieces 11 and 12 each having a predetermined shape.
a and 12a are joined at a temperature measuring contact 13. Of the pair of metal pieces 11 and 12, one metal piece 11 is, for example, chromel composed of small amounts of chromium and nickel, and the other metal piece 12 is, for example, alumel composed of nickel and small amounts of aluminum and manganese. Consists of

Each of the metal pieces 11 and 12 has an output terminal 11b at a positive potential and an output terminal 12b according to the environmental temperature of the temperature measuring contact 13.
Is a negative potential. That is, a thermoelectromotive force corresponding to the environmental temperature of the temperature measuring contact 13 is generated between the output terminals 11b and 12b. In this embodiment, the temperature measuring contact 13 is connected to the engine 6 (FIG. 2).
) In the exhaust path, and a thermoelectromotive force corresponding to the exhaust temperature of the engine 6 is generated between the output terminals 11b and 12b. A plurality of thermocouples 9 having such a configuration are provided, and each temperature measuring contact 13 is disposed in the exhaust path of the engine 6.

Each output terminal 11b, 12b of each thermocouple 9 is
It is connected to a temperature measurement circuit 10 shown in FIG. 2 via a harness (not shown) having a pair of signal lines. The temperature measurement circuit 10 has a number of input terminals (not shown) corresponding to the number of the thermocouples 9 and obtains an average voltage of each thermoelectromotive force applied between the input terminals corresponding to each thermocouple 9, This average voltage is supplied to the engine control device 7 and the temperature monitoring device 8.

The harness connecting each thermocouple 9 to the temperature measurement circuit 10 is directly connected to each thermocouple 9 and also connected to the temperature measurement circuit 10 by a connector. Further, the temperature measurement circuit 10, the engine control device 7, and the circuit 1
0 and the temperature monitoring device 8 are connected by a voltage transmission path formed by connecting a plurality of harnesses with connectors. The temperature distribution around the voltage transmission path (environmental temperature distribution) is substantially uniform. A connector 1 for connecting each harness
4 has substantially the same configuration as the connector 1 illustrated in FIG. 4, and a description of common parts will be omitted.

The connector 14 used in the present embodiment is different from the connector 1 in that a pair of sockets 14a ₁ , a part of which is shown in FIG. 14a ₂ ;
This is the point that a pair of pins 14b ₁ and 14b ₂ are provided. FIG.
Correspond to each socket 14a ₁ , 14a ₂ and each pin 14b
_1, 14b is a sectional view showing a partial configuration of the _2, each pin 14b _1, 14b ₂ shown in FIG, 15b _1, 1
5b ₂ pin body, 16b _1, 16b ₂ each pin body 1
This is a plating layer formed on the peripheral surfaces of 5b ₁ and 15b ₂ .

In each of the sockets 14a ₁ and 14a ₂ , 15a ₁ and 15a ₂ are connected to each of the pins 14b ₁ and 14b.
₂ and socket portions 16a ₁ and 16a ₂
Are the pins 14b of the socket portions 15a ₁ and 15a ₂
A plating layer formed on the contact surface with ₁ , 14b ₂ , 17a
_1, 17a ₂ is a support portion of the socket portion 15a _1, 15a _2.

[0028] Here, the metal strip 11 the socket 14a ₁ and pin 14b ₁ is formed of chromel (see FIG. 3)
And the socket 14a ₂ and the pin 14
b ₂ is electrically connected to the metal piece 12 (see FIG. 3) made of alumel. Accordingly, the socket portions 15a ₁ and pin body 15b ₁ are chromel, socket portion 15a ₂
And the pin body 15b ₂ is comprised of alumel.

Each plating layer 16a ₁ , 16a ₂ , 16
b ₁ and 16b ₂ are formed by plating a dissimilar metal, which is a metal material different from chromel / alumel. The dissimilar metal to be plated here is a metal having a higher electrical conductivity than chromel / alumel and a metal having a small contact resistance value with the chromel / alumel. Such a metal is hereinafter referred to as a "metal having excellent electrical conductivity". Also,
The above-mentioned dissimilar metals are not only excellent in electric conductivity but also soft and excellent in ductility as compared with chromel / alumel. Such a dissimilar metal, when plated on the socket and the pin, plays a role of improving the adhesiveness between the socket and the pin due to its excellent ductility, and also plays a role of a cushioning material.

Examples of the metal material satisfying the above conditions include gold, silver, cadmium, nickel, platinum and the like.
Basically, any of the above metal materials may be selected as a plating material. However, in this embodiment, it is used in an environment where a high temperature is expected around a jet engine, and the electric conductivity and In view of this, platinum having a heat-resistant temperature of 538 ° C. or gold having a heat-resistant temperature of 260 ° C. is used.

When a dissimilar metal is interposed in the voltage transmission path of the thermocouple, the intercalated dissimilar metal and chromel / alumel in contact with the dissimilar metal constitute a thermocouple in a pseudo manner. As a result, a thermoelectromotive force corresponding to the environmental temperature distribution around the voltage transmission path is generated. Therefore, there is a possibility that the thermoelectromotive force generated by the thermocouple disposed in the exhaust path may not be accurately transmitted to the next-stage control device, meter, or the like.

However, in the temperature detecting device 5 for the engine 6 of the aircraft shown in FIG. 2, since the environmental temperature distribution around the voltage transmission path is substantially uniform, the thermoelectromotive force generated by the pseudo thermocouple is extremely small. It will be small. Of course, the magnitude of the thermoelectromotive force generated by the pseudo thermocouple varies depending on the type of the metal material to be plated. Therefore, the pseudo thermocouple inserted in the path as the entire voltage transmission path. It is necessary to select a metal material so that the thermoelectromotive force generated by the pair is sufficiently smaller than the average voltage output from the temperature measurement circuit 10. Further, as a selection standard of the metal material, corrosion resistance, plating thickness, and the like are considered, and a material suitable for an application environment should be selected.

According to the above-described configuration, each thermocouple 9 generates a thermoelectromotive force between the output terminals 11b and 12b according to the exhaust gas temperature of the engine 6. Each generated thermoelectromotive force is transmitted to the temperature measurement circuit 10 via a pair of signal lines in the harness. Then, in the temperature measurement circuit 10, an average voltage of each thermoelectromotive force is obtained, and the average voltage is transmitted to the engine control device 7 and the temperature monitoring device 8 via a voltage transmission path.

Here, the voltage transmission process between the respective harnesses constituting the voltage transmission path will be described. The signal lines 2a ₁ and 2a ₂ of the cable 2a shown in FIG. 4 correspond to the socket portions 15a ₁ and 15a ₂ and the plating layers 16a ₁ and 16a shown in FIG.
_2, the plated layer 16b _1, 16b _2, each pin body 15b
₁ , 15b ₂ through each signal line 2b of the cable 2b
In conduction with _1, 2b _2. In these two conduction paths,
Plating layers 16a ₁ , 16b made of different metals, respectively
_{1. Because} the plating layers 16a ₂ and 16b ₂ are interposed,
A pseudo thermocouple is formed in each conduction path.

However, the environmental temperature distribution around the voltage transmission path is substantially uniform, and the plating layers 16a
_1, 16b _1, 16a _2, since the metal material constituting the 16b ₂ are selected in consideration of the environmental temperature around the voltage pathways plated layer _{16a 1, 16b 1, 16a 2} , 16b
_The thermoelectromotive force generated by the pseudo thermocouple including No. ₂ is extremely small, and the thermoelectromotive force generated by the insertion of the dissimilar metal in the entire voltage transmission path is measured by the temperature measurement circuit 10 (see FIG. 2).
Is sufficiently smaller than the average voltage output from

As in the prior art, the vibration of the engine 6 is transmitted to each connector via the harness, but the sockets 14a ₁ and 14a ₂ and the pins 14b ₁ and 14b ₂ provided on each connector 14 Since it is plated with a soft and highly ductile metal material, the adhesion between the fitted socket and the pin is improved, and the shock transmitted and received by the independent vibration of both is reduced.

Therefore, each of the sockets 14a ₁ , 14a
₂ and the contact surfaces of the pins 14b ₁ and 14b ₂ are worn down, and the possibility of generating wear powder is reduced. In other words, the occurrence cycle of the contact failure of the connector part becomes longer. For example, an experiment was conducted in which vibrations of a predetermined range of frequencies (frequency) were applied to the temperature detecting device 5 in which each of the plating layers 16a ₁ , 16a ₂ , 16b ₁ , 16b ₂ was made of gold. Thus, the cycle in which the contact failure occurs can be made about three times or more the length of the related art. A similar experiment was performed when a metal material other than gold was plated. Similarly, the cycle at which a contact failure occurred in the connector 14 could be made much longer than before.

The average voltage is supplied to the engine control device 7 and the temperature monitoring device 8 through the above-described voltage transmission process. As described above, since the thermoelectromotive force generated due to the insertion of the dissimilar metal is extremely small, the influence of the thermoelectromotive force on the entire voltage transmission path does not hinder accurate temperature measurement. The engine control device 7 to which the average voltage has been transmitted automatically controls the engine 6 according to the average voltage. Similarly, the temperature monitoring device 8 to which the average voltage has been transmitted,
The temperature represented by the average voltage is transmitted to the pilot.

As described above, each socket 14a
_1, 14a ₂ and to abrasion powder hardly occurs at each contact surface between each pin 14b _1, 14b _2, it is possible to lengthen the period of contact failure occurs in the connector 14. That is, the exhaust gas temperature of the engine 6 can be detected stably and accurately. For this reason, it is possible to reduce the probability that a serious problem such as the need to perform emergency maneuvering occurs in the aircraft in flight. That is, the reliability of the aircraft (system) can be improved.

In the above-described embodiment, a thermocouple composed of chromel / alumel is used.
A thermocouple made of a metal material other than these materials may be used. At this time, if both the metal pieces constituting the thermocouple are made of a sufficiently soft and highly ductile material, it is possible to obtain a desired material without plating with the above-mentioned various kinds of metals (eg, gold, platinum, etc.). The effect can be obtained.
In the above-described embodiment, the exhaust temperature of the jet engine of the aircraft is measured. However, the present invention is not limited to this. The temperature of the device under test is measured using a thermocouple, and the voltage transmission of the thermocouple is performed. If the temperature measuring device is such that the path is arranged in a vibration environment, the same effect as the temperature measuring device according to the above embodiment can be obtained.

[0041]

As described above, according to the present invention,
Since the voltage transmission path configured by connecting a plurality of harnesses to the connector is disposed in a vibration environment, each connection terminal vibrates independently for each of the harnesses. In the state where the connectors are connected, each connection terminal is in contact with the corresponding connection terminal. Therefore, when each of the connected connection terminals vibrates independently, the vector of the force applied (received) to each other becomes different. It fluctuates based on the frequency (frequency) of the connection terminal.

The change in the force vector is transmitted to the plating layer of each connection terminal. Since the plating layer is made of a metal material having excellent ductility, the plating layer is deformed in accordance with the applied force vector. Thereby, since the vibration is absorbed, the wear of each connection terminal surface can be suppressed. When the wear of each connection terminal surface is suppressed, the generated abrasion powder decreases,
Poor connector contact hardly occurs.

Further, since the plating layer is deformed in accordance with the vector of the applied force, the adhesion between the connection terminals can be improved. Therefore, the contact resistance between the connection terminals becomes large due to the vibration. Can be prevented. Further, since the metal material of the plating layer is excellent in electric conductivity, the rate of reduction of the voltage transmitted through the voltage transmission path can be reduced as compared with the case where the plating layer is not provided. Thus, there is an effect that the temperature of the device under test can be stably and accurately detected.

Further, by using gold having excellent electrical conductivity and ductility as the metal material, there is an effect that the temperature of the object to be measured can be detected stably and accurately in a general environment. (Claim 2). Further, by using platinum having excellent electrical conductivity, ductility, and heat resistance as the metal material, there is an effect that the temperature of the object to be measured can be stably and accurately detected even in a high-temperature environment ( Claim 3).

Further, the metal material is selected such that the thermoelectromotive force generated between the connection terminal and the plating layer made of the metal material is negligible in the entire voltage transmission path. In any temperature environment, there is an effect that the temperature of the measured object can be detected stably and accurately (claim 4). Further, a temperature measuring device using a specific metal material as a plating layer, the environmental temperature distribution around the voltage transmission path is substantially uniform, and the thermoelectromotive force generated between the connection terminal and the plating layer is: By using the voltage transmission path in an environment where the size of the voltage transmission path becomes negligible, the temperature of the device under test can be detected more stably and more accurately.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a partial configuration of a temperature detecting device 5 according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a control system to which the temperature detecting device 5 is applied.

FIG. 3 is a partial cross-sectional view showing a partial configuration of the temperature detection device 5 in an enlarged manner.

FIG. 4 is a diagram showing a structure of a connector 1 used in a conventional temperature detecting device.

[Explanation of symbols]

1,14 connector _{2a 1, 2a 2, 2b 1} , 2b 2 signal lines _{3a 1, 3a 2, 14a 1} , 14a 2 socket _{3b 1, 3b 2, 14b 1} , 14b 2 pin 5 temperature detection device 9 thermocouple 11, 12 metal piece _{16a 1, 16a 2, 16b 1} , 16b 2 plating layers

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-66195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01K 7/02

Claims (5)

(57) [Claims] 1. A thermocouple that generates a thermoelectromotive force according to the environmental temperature of a temperature measuring contact, and a voltage that is disposed in an oscillating environment and transmits the thermoelectromotive force generated by the thermocouple to a next-stage device. A transmission path, wherein the voltage transmission path is configured by connecting a plurality of harnesses with a connector, and the harness has a pair of signal lines made of the same kind of metal material as each of the metal pieces constituting the thermocouple. In the device, a temperature detection characterized in that the connection terminal constituting the connector is covered with a plating layer made of a metal material different from the metal piece and having excellent ductility and excellent electrical conductivity than the metal piece. apparatus. 2. The temperature detecting device according to claim 1, wherein the metal material is gold. 3. The temperature detecting device according to claim 1, wherein the metal material is platinum. 4. An environment temperature distribution around the voltage transmission path is substantially uniform, and a thermoelectromotive force generated between the connection terminal and the plating layer is large enough to be ignored in the entire voltage transmission path. The said metal material is selected so that it may become, The temperature detection apparatus of Claim 1 characterized by the above-mentioned. 5. The temperature detecting device according to claim 1, wherein an environmental temperature distribution around the voltage transmission path is substantially uniform, and heat generated between the connection terminal and the plating layer. A temperature detecting device for use in an environment in which an electromotive force is negligible in the entire voltage transmission path.