JP2009058403A

JP2009058403A - Thermocouple

Info

Publication number: JP2009058403A
Application number: JP2007226707A
Authority: JP
Inventors: Yoichi Mizuma; 陽一水真
Original assignee: Yamari Industries Ltd
Current assignee: Yamari Industries Ltd
Priority date: 2007-08-31
Filing date: 2007-08-31
Publication date: 2009-03-19

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermocouple that has versatility without requiring loading of a heating means such as an induction heating, electromagnetic stirring, and an IH heater, allows further improvement of noise removal rate, issues a stable command without being confused by noise even in a situation where alternating field arises from the heating means, and allows further accurate temperature measurement. <P>SOLUTION: Intervals D1 and D2 between different wires of sets of thermocouple wires 2A and 2B are set to be mutually substantially the same. Hot contacts 20A and 20B are arranged at mutually substantially the same length positions L1 and L2 so that the surfaces including different wires are in parallel and the circuit polarities of the different wires are reverse mutually. A circuit section 5 for interconnecting the thermocouple wires 2A and 2B in parallel or in series on the base end side is disposed. Electromotive forces induced in the thermocouple wires 2A and 2B are thereby canceled with each other, and the electromagnetic induction noise can be removed effectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、先端に温接点を有する一対の異種素線からなる熱電対に係わり、より詳しくは、外部磁場により誘起される電磁誘導ノイズを効果的に除去できる熱電対に関する。 The present invention relates to a thermocouple composed of a pair of heterogeneous wires having a hot junction at the tip, and more particularly to a thermocouple capable of effectively removing electromagnetic induction noise induced by an external magnetic field.

誘導加熱や電磁撹拌、半導体ヒータ、ＩＨヒータ等の加熱手段においては、導電性物質に交番磁界を与えて、うず電流損（強磁性体ではヒステリシス損も加わる）を生じさせて発熱させている。このような加熱手段の近傍に配置される熱電対の温度センサには、交番磁界による電磁誘導ノイズが生じ、温度指示が安定しないといった現象が生じている。 In heating means such as induction heating, electromagnetic stirring, semiconductor heaters, and IH heaters, an alternating magnetic field is applied to the conductive material to generate eddy current loss (addition of hysteresis loss in ferromagnetic materials) to generate heat. In such a thermocouple temperature sensor arranged in the vicinity of the heating means, a phenomenon in which electromagnetic induction noise due to an alternating magnetic field is generated and the temperature indication is not stable has occurred.

このような電磁誘導ノイズを防止するための技術として、従来、熱電対の温度センサに誘導又は誘電加熱装置の発振出力の開閉を制御する機能を付加して、計測の瞬間だけ誘導又は誘電加熱装置の発振出力を停止させて、計測のノイズとなる磁界及び電界を計測時のみ消失させるようにしたことを特徴とするシステムが提案されている（例えば、特許文献１参照。）。しかしながら、このようなシステムは加熱手段の動作を制御するための特別の回路及び装置が必要となり、大掛かりとなりコスト高となるとともに、汎用性のない温度センサとなってしまう。 Conventionally, as a technique for preventing such electromagnetic induction noise, a function for controlling the opening / closing of the oscillation output of the induction or dielectric heating device is added to the temperature sensor of the thermocouple, and the induction or dielectric heating device is used only at the moment of measurement. A system has been proposed in which the oscillation output is stopped and the magnetic field and electric field that become measurement noise are eliminated only during measurement (see, for example, Patent Document 1). However, such a system requires a special circuit and device for controlling the operation of the heating means, which increases the cost and costs, and results in a temperature sensor having no versatility.

これに対して、熱電対の温度センサ自体に電磁誘導ノイズを防止する構造上の工夫をするものとしては、従来、熱電対を構成する異種素線をツイストペアー化し、素線が螺旋状に配置された長手方向に沿って、反対方向の起電力が交互に発生するようにして隣同士、起電力を打ち消しあうように構成したものが提案されている（例えば、特許文献２参照。）。このような熱電対を用いれば、加熱装置に細工をすることなく汎用性のある温度センサを提供することが可能となる。しかし、このようなツイストペアー化した熱電対を正確に隣同士、同一面積の螺旋状に作製することは難しく、ノイズ除去率の向上には一定の限界があった。 On the other hand, to devise structural measures to prevent electromagnetic induction noise in the thermocouple temperature sensor itself, conventionally, the dissimilar strands that make up the thermocouple are twisted into pairs, and the strands are arranged in a spiral shape. A configuration has been proposed in which the electromotive forces in the opposite directions are alternately generated along the longitudinal direction so as to cancel the electromotive forces adjacent to each other (see, for example, Patent Document 2). If such a thermocouple is used, it becomes possible to provide a versatile temperature sensor without crafting the heating device. However, it is difficult to manufacture such twisted-pair thermocouples in a spiral shape with the same area adjacent to each other, and there is a certain limit to improving the noise removal rate.

特開平９−３０４１９３号公報Japanese Patent Laid-Open No. 9-304193 特開平８−８６６９４号公報JP-A-8-86694

そこで、本発明が前述の状況に鑑み、解決しようとするところは、誘導加熱や電磁撹拌、ＩＨヒータ等の加熱手段に細工することなく、汎用性があり、且つノイズ除去率の更なる向上が可能となり、加熱手段から交番磁界が生じる状況下においても、ノイズによって乱れることなく安定した指示をなし、より正しい温度計測を可能とする熱電対を提供する点にある。 Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem that there is versatility without further work on heating means such as induction heating, electromagnetic stirring, and IH heater, and the noise reduction rate can be further improved. It is possible to provide a thermocouple capable of giving a stable instruction without being disturbed by noise and enabling more accurate temperature measurement even under a situation where an alternating magnetic field is generated from the heating means.

本発明は、前述の課題解決のために、先端に温接点を備えた一対の異種素線より構成される熱電対線を複数設けてなる熱電対であって、２つの熱電対線よりなる組を単又は複数設け、前記組を成している各熱電対線を、互いに異種素線間の間隔を略同一に設定するとともに、各温接点が略同じ長さ位置で且つ異種素線の成す回路極性が互いに逆になるように設定しつつ、互いに異種素線を含む面同士が平行になるように並べて配置し、前記各熱電対素線を基端側において並列又は直列に接続する回路部を設け、外部磁場により各熱電対線に誘起される起電力を打ち消すように構成したことを特徴とする熱電対を構成した。 In order to solve the above-mentioned problems, the present invention is a thermocouple in which a plurality of thermocouple wires composed of a pair of different types of strands having a hot junction at the tip are provided, and is a set of two thermocouple wires. The thermocouple wires forming the set are set to have substantially the same distance between the different types of strands, and the hot junctions are formed at the same length and the different types of strands. A circuit unit that sets the circuit polarities to be opposite to each other and arranges the thermocouple wires in parallel or in series on the base end side by arranging the surfaces including different types of wires in parallel with each other. And a thermocouple characterized in that the electromotive force induced in each thermocouple wire by an external magnetic field is canceled out.

ここで、前記複数の熱電対線を金属シース内に納め、無機絶縁物で充填密封して一体化したものが好ましい。 Here, it is preferable that the plurality of thermocouple wires are housed in a metal sheath and are integrated by filling and sealing with an inorganic insulator.

前記組を成している平行な熱電対線を、ツイストペアー化したものが好ましい。 It is preferable that the parallel thermocouple wires forming the set are twisted pair.

前記各熱電対素線を基端側において直列に接続する回路部に、各熱電対素線よりなる２倍の熱起電力を半減化する半減化回路を設けたものが好ましい。 It is preferable that a circuit unit that connects the thermocouple wires in series on the base end side is provided with a halving circuit that halves the thermoelectromotive force that is twice that of the thermocouple wires.

前記回路部に、さらにローパスフィルタを設けたものが好ましい。 It is preferable that the circuit unit is further provided with a low-pass filter.

以上にしてなる本願発明に係る熱電対は、組を成している各熱電対線を、互いに異種素線間の間隔を略同一に設定するとともに、各温接点が略同じ長さ位置で且つ異種素線の成す回路極性が互いに逆になるように設定しつつ、互いに異種素線を含む面同士が平行になるように並べて配置することにより、熱電対に交差する磁束の変化によって各熱電対線に誘起される電磁誘導起電力を、互いに大きさが等しく且つ位相が１８０°ずれたものとすることができ、このような各熱電対素線を基端側において並列又は直列に接続する回路部により、この起電力を互いに打ち消して純粋な測定用の熱起電力出力を得ることができるため、従来のツイストペアー化したものに比べて、設計上の精度アップを図ることが容易であるため、さらなるノイズ除去率の向上を図ることが可能となる。 In the thermocouple according to the present invention having the above-described configuration, the thermocouple wires forming the set are set to have substantially the same spacing between the different types of strands, and the hot junctions are at substantially the same length and position. By setting the circuit polarities of the different types of strands to be opposite to each other and arranging the planes containing the different types of strands in parallel with each other, each thermocouple can be changed by changing the magnetic flux crossing the thermocouple. Circuits in which electromagnetic induction electromotive forces induced in the wires can be equal in magnitude and out of phase by 180 °, and such thermocouple wires are connected in parallel or in series on the base end side Because it is possible to cancel out these electromotive forces by each other and obtain a thermoelectromotive force output for pure measurement, it is easy to improve design accuracy compared to the conventional twisted pair. , Further noise removal It is possible to achieve the rate enhancement of.

次に、本発明の実施形態を添付図面に基づき詳細に説明する。 Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

図１（ａ）は、本発明に係る熱電対１の全体構成を示す概略図であり、図１〜５は代表的実施形態を示し、図中符号１は熱電対、２Ａ，２Ｂは組を成す２つの熱電対線、３は金属シース、４は無機絶縁物、５は回路部、６は補償導線、７は計測器をそれぞれ示している。 FIG. 1A is a schematic diagram showing the overall configuration of a thermocouple 1 according to the present invention. FIGS. 1 to 5 show typical embodiments, in which 1 is a thermocouple, 2A and 2B are pairs. Two thermocouple wires are formed, 3 is a metal sheath, 4 is an inorganic insulator, 5 is a circuit section, 6 is a compensating conductor, and 7 is a measuring instrument.

本発明の熱電対１は、図１（ａ）に示すように、金属シース３内部に、異種素線２１Ａ(+)，２１Ａ(-)よりなり先端側に温接点２０Ａを形成した熱電対線２Ａと、同じく温接点２０Ｂを先端に形成した異種素線２１Ｂ(+)，２１Ｂ(-)よりなる熱電対線２Ｂとの２つの熱電対線からなる組を一組設けたものである。これら熱電対線２Ａ，２Ｂは、従来と同様、たとえばプラス側素線にニッケル−クロム合金、マイナス側素線にニッケル合金を用いることができるが、とくに限定されるものではない。 As shown in FIG. 1 (a), the thermocouple 1 of the present invention is a thermocouple wire in which a hot junction 20A is formed on the distal end side of a dissimilar strand 21A (+), 21A (-) inside a metal sheath 3. A set of two thermocouple wires is provided, 2A, and a thermocouple wire 2B made of a heterogeneous strand 21B (+), 21B (-) having a hot junction 20B at the tip. For these thermocouple wires 2A and 2B, for example, a nickel-chromium alloy can be used for the plus side strand and a nickel alloy can be used for the minus side strand, but there is no particular limitation.

そして、本発明では特に、図１（ｂ）の断面図にも示すように、これら組をなす熱電対線２Ａ，２Ｂの各異種素線の間隔Ｄ１，Ｄ２を互いに略同一に設定するとともに、各温接点２０Ａ，２０Ｂが互いに略同じ長さ位置Ｌ１，Ｌ２で、かつ異種素線を含む面同士が互いに平行であり、さらに異種素線の成す回路極性が互いに逆になるように、即ち、たとえば従来のDuplex Thermocouple Cableの断面素線配置と同じように、平行に配置される各熱電対線２Ａ，２Ｂの同じ側に配置される素線２１Ａ，２１Ｂが異なる極性となるように並べて配置し、さらに各熱電対線２Ａ，２Ｂを基端側において並列又は直列に接続する回路部５を設けることにより、熱電対１に交差する外部磁界の磁束変化によって各熱電対線２Ａ，２Ｂに誘起される起電力が打ち消され、電磁誘導ノイズを効果的に除去できるように構成したことを特徴としている。なお、各素線は上記直列又は並列接続以外に接続箇所はない。 And especially in this invention, as shown also in sectional drawing of FIG.1 (b), while setting the space | interval D1, D2 of each dissimilar strand of the thermocouple wire | wire 2A, 2B which comprises these sets mutually substantially the same, The hot junctions 20A and 20B have substantially the same length positions L1 and L2, and the surfaces including the different strands are parallel to each other, and the circuit polarities formed by the different strands are opposite to each other, that is, For example, in the same manner as the cross-sectional wire arrangement of the conventional Duplex Thermocouple Cable, the wires 21A and 21B arranged on the same side of the thermocouple wires 2A and 2B arranged in parallel are arranged side by side so as to have different polarities. Further, by providing the circuit unit 5 for connecting the thermocouple wires 2A and 2B in parallel or in series on the base end side, the thermocouple wires 2A and 2B are induced by the magnetic flux change of the external magnetic field intersecting the thermocouple 1. EMF is canceled Therefore, the electromagnetic induction noise can be effectively removed. Each strand has no connection place other than the series or parallel connection.

つまり、図２のように交番磁界があるとき、磁束が変化してレンツの法則により２１Ａ(+)，２１Ａ(-)にプラスの電磁誘導が発生すれば、２１Ｂ(-)，２１Ｂ(+)にはマイナスの電磁誘導が発生する。電磁誘導電圧の大きさは、素線の配置が、熱電対線２Ａ，２Ｂで互いに対称にあり、磁場に比して素線間の距離は十分に小さいことから、素線近傍の磁場は互いに平行磁場とみなされる。その結果、素線２１Ａ(+)，２１Ａ(-)の熱電対線２Ａに誘起される電磁誘導電圧の大きさは、素線２１Ｂ(-)，２１Ｂ(+)の熱電対線２Ｂに誘起される電磁誘導電圧の大きさと等しく、かつ位相は１８０°ずれている。よって、双方の誘導電圧は打ち消しあって電磁誘導ノイズを抑えることができるのである。 That is, when there is an alternating magnetic field as shown in FIG. 2, if the magnetic flux changes and positive electromagnetic induction occurs in 21A (+) and 21A (-) according to Lenz's law, 21B (-) and 21B (+) Negative electromagnetic induction occurs. The magnitude of the electromagnetic induction voltage is such that the arrangement of the strands is symmetric with respect to the thermocouple wires 2A and 2B, and the distance between the strands is sufficiently small compared to the magnetic field. Considered as a parallel magnetic field. As a result, the magnitude of the electromagnetic induction voltage induced in the thermocouple wire 2A of the strands 21A (+) and 21A (−) is induced in the thermocouple wire 2B of the strands 21B (−) and 21B (+). Is equal to the magnitude of the electromagnetic induction voltage, and the phase is shifted by 180 °. Therefore, both induction voltages cancel each other and electromagnetic induction noise can be suppressed.

図３に基づき、電磁誘導ノイズが打ち消す理由について詳しく説明する。熱電対（閉回路）を鎖交する磁束が時間的に変化すると、電磁誘導により、回路に電圧を誘起し、電流が流れる。誘起電圧の大きさは、磁束φ〔Ｗｂ〕の変化する早さに比例する。熱電対を１ターンのコイルとし、時間ｔ〔ｓ〕とすれば、熱電対の誘起電圧ｅ〔Ｖ〕は、ｅ＝−ｄφ／ｄｔで示される。（ノイマンの法則）また、誘起電圧の方向は、熱電対と鎖交する磁束が変化するとき、その変化を妨げるような方向に電流を流そうとする電圧が誘起する（レンツの法則）。すなわち、磁束の減少する場合には、磁束と誘起電圧の方向はアンペアの右ネジの法則に従う。この場合の誘起電圧の方向を正とすると、２対の熱電対の誘起電圧は図に示す方向に生じ、並列接続は同じ極性同士を、直列接続は異なる極性を接続することで指示計器の内部抵抗Ｒ（Ｒ_I）に流れる電流の向きが逆で、２対の熱電対の寸法規格を極力同じにすることで鎖交する磁束が同じになり、誘起電圧は打ち消しあって電磁誘導ノイズは少なくなるのである。 Based on FIG. 3, the reason why electromagnetic induction noise cancels will be described in detail. When the magnetic flux interlinking the thermocouple (closed circuit) changes with time, a voltage is induced in the circuit by electromagnetic induction, and a current flows. The magnitude of the induced voltage is proportional to the speed at which the magnetic flux φ [Wb] changes. If the thermocouple is a one-turn coil and the time is t [s], the induced voltage e [V] of the thermocouple is represented by e = −dφ / dt. (Neumann's Law) As for the direction of the induced voltage, when the magnetic flux interlinking with the thermocouple changes, a voltage that induces a current in a direction that prevents the change is induced (Lenz's law). That is, when the magnetic flux decreases, the direction of the magnetic flux and the induced voltage follows the right-hand rule of amperes. In this case, if the direction of the induced voltage is positive, the induced voltage of the two thermocouples is generated in the direction shown in the figure. The parallel connection connects the same polarity, and the series connection connects the different polarities. The direction of the current flowing through the resistor R (R _I ) is opposite. By making the dimensional specifications of the two thermocouples the same as much as possible, the interlinkage magnetic flux becomes the same, the induced voltage cancels out, and the electromagnetic induction noise is small It becomes.

本実施形態においては、複数の熱電対線２Ａ，２Ｂを金属シース３内に納め、無機絶縁物４で充填密封して一体化しており、従来と同様、金属シース３としては、オーステナイト系ステンレス鋼（ＳＵＳ３０４、ＳＵＳ３１６等）やニッケルクローム系耐熱合金（インコネル）等を用いることができ、シース内に充填する無機絶縁物４として、酸化マグネシウム（ＭｇＯ）等を用いることができる。なお、本発明の熱電対はこのような構造に何ら限定されず、無機絶縁物４を充填するかわりにガイド部材を設け、該ガイド部材の挿通穴に素線を挿通するように構成したものや、素線を碍子で被覆して構成したものでもよい。また、本実施形態のように温接点をシース内に収納したもの以外に、先端の温接点をシース外に露出させた構造としてもよい。 In the present embodiment, a plurality of thermocouple wires 2A and 2B are housed in a metal sheath 3 and integrated by filling and sealing with an inorganic insulator 4. As in the conventional case, as the metal sheath 3, austenitic stainless steel is used. (SUS304, SUS316, etc.), nickel chrome heat-resistant alloy (Inconel) or the like can be used, and magnesium oxide (MgO) or the like can be used as the inorganic insulator 4 filled in the sheath. The thermocouple of the present invention is not limited to such a structure. Instead of filling the inorganic insulator 4, a guide member is provided, and a wire is inserted into the insertion hole of the guide member. In addition, it may be configured by covering the strands with insulators. Moreover, it is good also as a structure which exposed the warm junction of the front-end | tip outside the sheath other than what accommodated the warm junction in the sheath like this embodiment.

本発明は、熱電対線２Ａ，２Ｂの各異種素線の間隔Ｄ１，Ｄ２、温接点２０Ａ，２０Ｂの長さ位置Ｌ１，Ｌ２をそれぞれ略同じに設定し、かつ互いに平行とすることで、各熱電対線２Ａ，２Ｂの素線でなす回路内面積を略同じに設定し、これにより該回路内を通過する磁束変化量を略同じにして最終的に起電力を打ち消すように構成したものであり、これら間隔や長さ位置、平行の設定は重要である。上記面積を略同じにするためには、異種素線の先端に温接点を形成する際に形成される三角形も、それぞれ温接点２０Ａ，２０Ｂで同じ形状となるようにすればよい。 In the present invention, the distances D1 and D2 between the different kinds of strands of the thermocouple wires 2A and 2B and the length positions L1 and L2 of the hot junctions 20A and 20B are set substantially the same and parallel to each other. The area in the circuit formed by the strands of the thermocouple wires 2A and 2B is set to be substantially the same, thereby the amount of change in magnetic flux passing through the circuit is made substantially the same, and the electromotive force is finally canceled. Yes, the setting of the interval, length position, and parallelism is important. In order to make the above areas substantially the same, the triangles formed when the hot junction is formed at the tip of the dissimilar element wire may have the same shape at the hot junctions 20A and 20B, respectively.

また、本実施形態では、図１に示すように、回路部５をシース基端側に、例えば図示しない保護管等を介して設けられる端子箱内に設置するなどして一体的に構成し、そこから補償導線６、６を用いて計測器７に接続するように構成しているが、その他、図６に示すように、シース基端側に一体的に設けるのではなく、各素線２１Ａ，２１Ｂの基端側にコネクタ等を介して接続される補償導線６，…を用いて、別途構成した回路部５に接続し、さらに回路部５から補償導線６等により計測器７に接続するように構成するなど、回路部５の位置については特に限定されない。 Further, in the present embodiment, as shown in FIG. 1, the circuit unit 5 is configured integrally with the sheath base end side, for example, by being installed in a terminal box provided via a protective tube (not shown), From there, it is configured so as to be connected to the measuring instrument 7 using the compensating lead wires 6 and 6. In addition, as shown in FIG. , 21B is connected to the circuit unit 5 separately configured using the compensating lead wires 6,... Connected to the base end side via connectors or the like, and further connected to the measuring instrument 7 from the circuit unit 5 by the compensating lead wire 6 or the like. For example, the position of the circuit unit 5 is not particularly limited.

まず、熱電対線２Ａ，２Ｂを回路部５で直列接続した場合の電磁誘導ノイズの除去の原理について説明する。図４（ａ）は、直列接続した回路部５の構成を示しており、図４（ｂ）はその電気的等価回路を示している。尚、本例では、直列接続により各熱電対線２Ａ，２Ｂから取得される熱起電力の総和を半減化（平均化）するた、抵抗Ｒ、Ｒよりなる半減化回路を設け、計測器に入力される熱起電力をそのまま使用できるようにしているが、このような半減化は特に必須ではない。 First, the principle of electromagnetic induction noise removal when the thermocouple wires 2A and 2B are connected in series by the circuit unit 5 will be described. 4A shows a configuration of the circuit units 5 connected in series, and FIG. 4B shows an electrical equivalent circuit thereof. In this example, a halving circuit consisting of resistors R and R is provided to halve (average) the sum of the thermoelectromotive forces acquired from the thermocouple wires 2A and 2B by serial connection, and the measuring instrument Although the input thermoelectromotive force can be used as it is, such halving is not particularly essential.

図４（ｂ）の等価回路において、ｒ_A，ｒ_Bは、それぞれ熱電対線２Ａ，２Ｂの素線抵抗、Ｅ_A，Ｅ_Bは、それぞれ熱電対線２Ａ，２Ｂの熱起電力（ＤＣ）（本来の測定用熱起電力）、Ｖ_A，Ｖ_Bは、それぞれ熱電対線２Ａ，２Ｂの外部磁場による電磁誘導電圧（ＡＣ）（電磁誘導ノイズの原因となる誘導起電力）をそれぞれ示しており、Ｒ_I≫Ｒ、Ｒ≫ｒ_A，ｒ_Bの条件が成立する。この等価回路より、キルヒホフの法則から次式が得られる。
Ｅ₀＝（Ｅ_A＋Ｅ_B＋Ｖ_A＋Ｖ_B）／２ In the equivalent circuit of FIG. 4B, r _A and r _B are the wire resistances of the thermocouple wires 2A and 2B, respectively, and E _A and E _B are the thermoelectromotive forces (DC) of the thermocouple wires 2A and 2B, respectively. (Original thermoelectromotive force for measurement), V _A and V _B respectively indicate electromagnetic induction voltage (AC) (inductive electromotive force that causes electromagnetic induction noise) due to the external magnetic field of thermocouple wires 2A and 2B. Thus, the conditions of R _I >> R, R >> r _A , r _B are satisfied. From this equivalent circuit, the following equation is obtained from Kirchhoff's law.
E ₀ = (E _A + E _B + V _A + V _B ) / 2

ここで、測温接点の温度は同じであるから、Ｅ_A＝Ｅ_Bである。また、Ｖ_A，Ｖ_Bは交流電圧であり、その大きさは等しく位相は１８０°ずれているので、Ｖ_A＋Ｖ_B＝０である。したがって、Ｅ₀＝Ｅ_A＝Ｅ_Bとなり、電磁誘導ノイズは相殺され、熱起電力のみ測定できることとなる。ただし、熱電対線２Ａ，２Ｂの素線のなす回路内面積に多少の不均一があれば電磁誘導ノイズが少々発生することが避けられないが、これについては、回路部５にさらにローパスフィルタを構成することで除去できる。具体的には、図４（ａ），（ｂ）にそれぞれ破線で示すようなコンデンサＣを追加することが好ましい。 Here, since the temperature of the temperature measuring junction is the same, E _A = E _B. V _A and V _B are alternating voltages, and their magnitudes are equal and the phase is shifted by 180 °, so that V _A + V _B = 0. Therefore, E ₀ = E _A = E _B , electromagnetic induction noise is canceled out, and only the thermoelectromotive force can be measured. However, it is inevitable that a little electromagnetic induction noise will be generated if there is some non-uniformity in the circuit area formed by the strands of the thermocouple wires 2A and 2B. It can be removed by configuring. Specifically, it is preferable to add a capacitor C as shown by broken lines in FIGS. 4 (a) and 4 (b).

次に、熱電対線２Ａ，２Ｂを回路部５で並列接続した場合の電磁誘導ノイズの除去の原理について説明する。図５（ａ）は、熱電対線２Ａ，２Ｂを並列接続した回路部５を示しており、図５（ｂ）はその電気的等価回路を示している。 Next, the principle of removing electromagnetic induction noise when the thermocouple wires 2A and 2B are connected in parallel by the circuit unit 5 will be described. FIG. 5A shows the circuit unit 5 in which the thermocouple wires 2A and 2B are connected in parallel, and FIG. 5B shows an electrical equivalent circuit thereof.

図５（ｂ）の等価回路において、ｒ_A，ｒ_Bは、それぞれ熱電対線２Ａ，２Ｂの素線抵抗、Ｅ_A，Ｅ_Bは、それぞれ熱電対線２Ａ，２Ｂの熱起電力（ＤＣ）、Ｖ_A，Ｖ_Bは、それぞれ熱電対線２Ａ，２Ｂの外部磁場による電磁誘導電圧（ＡＣ）をそれぞれ示しており、Ｒ_I≫ｒ、ｒ_A＝ｒ_B＝ｒの条件が成立する。Ｖ_A，Ｖ_Bは交流電圧であり、その大きさは等しく位相は１８０°ずれている。この等価回路より、キルヒホフの法則から次式が得られる。 In the equivalent circuit of FIG. 5B, r _A and r _B are the wire resistances of the thermocouple wires 2A and 2B, respectively, and E _A and E _B are the thermoelectromotive forces (DC) of the thermocouple wires 2A and 2B, respectively. , V _A , V _B respectively indicate electromagnetic induction voltages (AC) due to the external magnetic fields of the thermocouple wires 2A, 2B, and the conditions of R _I >> r and r _A = r _B = r are satisfied. V _A and V _B are alternating voltages, and their magnitudes are equal and their phases are shifted by 180 °. From this equivalent circuit, the following equation is obtained from Kirchhoff's law.

ｉ_A＝（Ｅ_A＋Ｖ_A−Ｅ₀）／ｒ_A ・・・（１）
ｉ_B＝（Ｅ_B＋Ｖ_B−Ｅ₀）／ｒ_B ・・・（２）
Ｅ₀＝Ｒ_I（ｉ_A＋ｉ_B）・・・（３）
（１）、（２）を（３）に代入して、
Ｅ₀／Ｒ_I＝（Ｅ_A＋Ｖ_A）／ｒ_A＋（Ｅ_B＋Ｖ_B）／ｒ_B−（Ｅ₀／ｒ_A＋Ｅ₀／ｒ_B）
Ｅ₀（１／Ｒ_I＋１／ｒ_A＋１／ｒ_B）＝Ｅ_A／ｒ_A＋Ｅ_B／ｒ_B＋Ｖ_A／ｒ_A＋Ｖ_B／ｒ_B
ここで、ｒ_A＝ｒ_B＝ｒより、
Ｅ₀（１／Ｒ_I＋２／ｒ）＝（Ｅ_A＋Ｅ_B）／ｒ＋（Ｖ_A＋Ｖ_B）／ｒ i _A = (E _A + V _A −E ₀ ) / r _A (1)
i _B = (E _B + V _B −E ₀ ) / r _B (2)
E ₀ = R _I (i _A + i _B ) (3)
Substituting (1) and (2) into (3),
E ₀ / R _I = (E _A + V _A ) / r _A + (E _B + V _B ) / r _B − (E ₀ / r _A + E ₀ / r _B )
E ₀ (1 / R _I + 1 / r _A + 1 / r _B ) = E _A / r _A + E _B / r _B + V _A / r _A + V _B / r _B
Here, from r _A = r _B = r,
E ₀ (1 / R _I + 2 / r) = (E _A + E _B ) / r + (V _A + V _B ) / r

また、Ｖ_A＋Ｖ_B＝０であるから、
Ｅ₀（１／Ｒ_I＋２／ｒ）＝（Ｅ_A＋Ｅ_B）／ｒとなり、電磁誘導ノイズは相殺され、熱起電力のみ測定できることとなる。
そして、Ｒ_I≫ｒであるので、
２Ｅ₀／ｒ＝（Ｅ_A＋Ｅ_B）／ｒ
したがって、Ｅ₀＝（Ｅ_A＋Ｅ_B）／２となる。 Since V _A + V _B = 0,
E ₀ (1 / R _I + 2 / r) = (E _A + E _B ) / r, electromagnetic induction noise is canceled out, and only the thermoelectromotive force can be measured.
And since R _I >> r,
2E ₀ / r = (E _A + E _B ) / r
Therefore, E ₀ = (E _A + E _B ) / 2.

この並列接続においても、同じくローパスフィルタを構成することが好ましい。具体的には、図５（ａ）において破線で示すようなコンデンサＣ、及び必要に応じて外付け抵抗Ｒを入れることがローパスフィルタを構成することができる。
Ｔ：ローパスフィルタの時定数（Time Consatant）
Ｔ＝（ｎ_e＋Ｒ）・Ｃ
ここで、１／ｎ_e＝１／Ｒ_A＋１／Ｒ_B
Ｒ_A＝Ｒ_Bとすると、ｎ_e＝Ｒ_A／２
電磁誘導ノイズの周波数（一番低い周波数、一般的には基本周波数）をｆ_minとすると、
Ｔ≫１／２πｆ_min
Ｔ＝１０／２πｆ_minとすると、周波数ｆ_minの電磁誘導ノイズは１／１０に低減する。 Also in this parallel connection, it is preferable that a low-pass filter is also configured. Specifically, a low-pass filter can be configured by inserting a capacitor C as indicated by a broken line in FIG. 5A and an external resistor R as required.
T: Time constant of the low-pass filter (Time Constant)
T = ( _ne + R) · C
Where 1 / n _e = 1 / R _A + 1 / R _B
If R _A = R _B , then _ne = R _A / 2.
If f _min is the frequency of electromagnetic induction noise (the lowest frequency, generally the fundamental frequency),
T >> 1 / 2πf _min
When T = 10 / 2πf _min , the electromagnetic induction noise at the frequency f _min is reduced to 1/10.

なお、本実施形態では、各熱電対線２Ａ，２Ｂを構成している素線２１Ａ，２１Ｂをそれぞれストレートに構成しているが、図７に示すように、全体を螺旋状にねじり、熱電対線２Ａ，２Ｂ同士の平行関係を維持したままツイストペアー化することも好ましい実施例である。本発明は、熱電対線２Ａ，２Ｂ同士で、互いに生じた誘電起電力を打ち消しあうように構成するものであるが、本例のようにツイストペアー化することにより、各熱電対線に生じる誘導起電力自体をそれぞれ最小化することができ、打ち消しあう場合の誤差をより小さなものとしてノイズ除去率をより高めることが可能となる。 In the present embodiment, the strands 21A and 21B constituting the thermocouple wires 2A and 2B are straight, respectively. However, as shown in FIG. It is also a preferred embodiment to form a twisted pair while maintaining the parallel relationship between the lines 2A and 2B. In the present invention, the thermocouple wires 2A and 2B are configured so as to cancel each other's dielectric electromotive force, but by forming a twisted pair as in this example, induction generated in each thermocouple wire. Each of the electromotive forces can be minimized, and the noise removal rate can be further increased by making the error when canceling each other smaller.

また、本実施形態では、互いに誘導起電力を打ち消しあう熱電対線２Ａ，２Ｂの組を一組のみ設けた例を説明したが、図８に示すように、互いに打ち消しあう熱電対線２Ａ，２Ｂと、同じく打ち消しあう熱電対線２Ｃ、２Ｄとを設けて、二組以上とすることもできる。この場合、打ち消しあう熱電対線を互いに平行に配置できれば、図中（ａ）、（ｂ）に示すように種々の配置が可能である。勿論、三組以上設けることも可能である。また、打ち消しあう熱電対線の組以外に、単独の熱電対線を別途有していてもよい。 Moreover, in this embodiment, although the example which provided only one set of thermocouple wire 2A, 2B which mutually cancels an induced electromotive force was demonstrated, as shown in FIG. 8, thermocouple wire 2A, 2B which mutually cancels Also, two or more sets of thermocouple wires 2C and 2D that cancel each other out can be provided. In this case, if the thermocouple wires that cancel each other can be arranged in parallel to each other, various arrangements are possible as shown in FIGS. Of course, three or more sets can be provided. Further, in addition to the set of thermocouple wires that cancel each other, a single thermocouple wire may be separately provided.

以上本発明の実施形態について説明したが、本発明はこうした実施例に何ら限定されるものではなく、本発明の要旨を逸脱しない範囲において種々なる形態で実施し得ることは勿論である。 Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

以下、本発明の実施例について、ノイズ除去効果を確認する試験を行った結果について説明する。 Hereinafter, the result of having performed the test which confirms the noise removal effect about the Example of this invention is demonstrated.

（実施例（評価対象品））
Ｋシース熱電対（非接地型、外径3.2mm、1000mm）１本 (Example (product to be evaluated))
One K-sheath thermocouple (non-grounded type, outer diameter 3.2 mm, 1000 mm)

（評価機器）
交番磁界発生器：ＩＨクッキングヒータ「CS-H2201B型」（三菱電機社製）（最大出力2.0KW）
誘起電圧測定器：デジタル交流電圧計「2000型 Ser.No.0732016」（KEIHELEY社製）（分解能１μVの実効値表示）
誘起波形測定器：ブラウン管オシロスコープ「SS-7804型、Ser.No.714718456」（岩通社製） (Evaluation equipment)
Alternating magnetic field generator: IH cooking heater "CS-H2201B type" (Mitsubishi Electric Corporation) (maximum output 2.0KW)
Induced voltage measuring instrument: Digital AC voltmeter "2000 type Ser.No.0732016" (manufactured by KEIHELEY) (effective value display with 1 μV resolution)
Induced waveform measuring instrument: CRT oscilloscope "SS-7804, Ser.No.714718456" (Iwatori)

（評価方法）
実施例のシースの中間部分を交番磁界発生器（直径180mm）の上に乗せ、その横に水を入れた鉄なべを乗せて、発生器を正常動作させた。一つの熱電対線に交流電圧測定器を接続して、誘起交流電圧が最高の値を示すように、発生器上のシースの位置を微妙に変えて、最高値でシースを固定した。シース内の２つの熱電対線の各々の誘起交流電圧ｅ₁，ｅ₁’を測定して、２対を直列または並列に接続したときの誘起電圧ｅ₂を測定した。そして、次式より、電磁誘導ノイズの除去率Nを求めた。評価結果は、下記の表１のとおりとなった。
Ｎ＝２０・log₁₀（ｅ₁／ｅ₂） (Evaluation methods)
The intermediate portion of the sheath of the example was placed on an alternating magnetic field generator (diameter 180 mm), and an iron pan filled with water was placed next to the generator to operate the generator normally. An AC voltage measuring instrument was connected to one thermocouple wire, and the position of the sheath on the generator was slightly changed so that the induced AC voltage showed the highest value, and the sheath was fixed at the highest value. The induced AC voltages e ₁ and e ₁ ′ of the two thermocouple wires in the sheath were measured, and the induced voltage e ₂ when the two pairs were connected in series or in parallel was measured. And the removal rate N of electromagnetic induction noise was calculated | required from following Formula. The evaluation results are as shown in Table 1 below.
N = 20 · log ₁₀ (e ₁ / e ₂ )

上記結果より、電磁誘導ノイズ除去の効果を、素線を撚った場合と比べて、約１００ｍｍピッチの撚り（２３ｄＢ）の効果とほぼ同等の効果が得られることが確認できた。 From the above results, it was confirmed that the effect of removing electromagnetic induction noise was almost the same as the effect of twisting with a pitch of about 100 mm (23 dB) as compared with the case where the strand was twisted.

（ａ）は本発明に係る熱電対の全体構成を示す説明図、（ｂ）は同じく断面図。(A) is explanatory drawing which shows the whole structure of the thermocouple based on this invention, (b) is sectional drawing similarly. 交番磁界が生じた様子を示す模式図。The schematic diagram which shows a mode that the alternating magnetic field produced. 外部磁場により電磁誘導起電力が発生するとともに、これが打ち消しあう様子を示す模式図。The schematic diagram which shows a mode that electromagnetic induction electromotive force generate | occur | produces with an external magnetic field, and this cancels. （ａ）は直列接続した回路構成を示しており、（ｂ）はその電気的等価回路。(A) has shown the circuit structure connected in series, (b) is the electrical equivalent circuit. （ａ）は並列接続した回路構成を示しており、（ｂ）はその電気的等価回路。(A) has shown the circuit structure connected in parallel, (b) is the electrical equivalent circuit. 回路部をシース基端側に一体的に設けるのではなく別途構成した変形例を示す説明図。Explanatory drawing which shows the modification which comprised separately rather than providing a circuit part integrally in the sheath base end side. 熱電対線同士の平行関係を維持したままツイストペアー化した変形例を示す説明図。Explanatory drawing which shows the modification made into twisted pair, maintaining the parallel relationship of thermocouple wires. （ａ），（ｂ）は、それぞれ生じた誘導起電力を打ち消しあう熱電対線を二組以上設けた変形例を示す断面図。(A), (b) is sectional drawing which shows the modification which provided two or more sets of thermocouple wires which cancel each induced electromotive force.

Explanation of symbols

１熱電対
２Ａ，２Ｂ，２Ｃ各熱電対線
３シース
４無機絶縁物
５回路部
６補償導線
７計測器
２０Ａ，２０Ｂ温接点
２１Ａ，２１Ｂ素線 DESCRIPTION OF SYMBOLS 1 Thermocouple 2A, 2B, 2C Each thermocouple wire 3 Sheath 4 Inorganic insulator 5 Circuit part 6 Compensation lead 7 Measuring instrument 20A, 20B Hot junction 21A, 21B Wire

Claims

A thermocouple provided with a plurality of thermocouple wires composed of a pair of different types of strands having a hot junction at the tip, and a single or a plurality of sets consisting of two thermocouple wires are provided, forming the set The thermocouple wires are set so that the distances between the different types of strands are set to be substantially the same, and the hot junctions are set at substantially the same length and the circuit polarities of the different types of strands are reversed. , Arranged so that the surfaces including different kinds of strands are parallel to each other, and provided with a circuit portion for connecting the thermocouple wires in parallel or in series on the base end side, induced by the external magnetic field to each thermocouple wire A thermocouple configured to cancel the electromotive force.

The thermocouple according to claim 1, wherein the plurality of thermocouple wires are housed in a metal sheath and are integrated by filling and sealing with an inorganic insulator.

The thermocouple according to claim 1 or 2, wherein the parallel thermocouple wires forming the set are formed into a twisted pair.

The circuit part which connects each said thermocouple strand in series in the base end side WHEREIN: The halving circuit which halves the thermoelectromotive force of 2 times which consists of each thermocouple strand is provided. The thermocouple according to item 1.

The thermocouple according to any one of claims 1 to 4, wherein a low-pass filter is further provided in the circuit unit.