JPWO2006046358A1 - Equipment with high frequency coil - Google Patents

Abstract

The conductive object detection / measurement device includes a coil 11 facing the conductive object 20 in a non-contact manner, and a voltage measuring device 19 that measures the output voltage of the coil 11. A device for detecting and measuring a conductive object by measuring a change in the output voltage of the coil 11 due to an eddy current flowing inside the object 20 with a voltage measuring device 19, wherein the wire 10 of the detection coil 11 has a magnetic body around the outer periphery. A copper wire 1 covered with layers 3 and 5. The high-frequency transformer is a copper wire in which, in the high-frequency transformer including at least the primary side coil 25 and the secondary side coil 27, the wire 10 of the coils 25 and 27 covers the outer periphery with the magnetic layers 3 and 5.

Description

  The present invention relates to a device including a high-frequency coil that excites electromagnetic waves, specifically to a device for detecting and measuring a conductive object, a proximity switch, and a high-frequency transformer including a high-frequency coil.

It is known that when an electromagnetic wave is oscillated from a high-frequency coil, an electromagnetic induction current flows through a conductive object in the magnetic field. Various sensors have been developed using the induced eddy current generated by the high-frequency coil. For example, Japanese Patent Laid-Open No. 9-277070 discloses a gap sensor for preventing laser processing head impact. Japanese Patent Application Laid-Open No. 7-83606 discloses a non-contact clearance measurement for a wood chip refiner, Japanese Patent Application Laid-Open No. 2002-4773 measures a distance of a driving shaft of a cutter used for excavation work, and Japanese Patent Application Laid-Open No. 11-165430. JP-A-8-184579 discloses a variety of sensors such as detection of the thickness of an image recording sheet, JP-A-8-184579, determination of a metal material, and JP-A-2-201101, a magnetic bearing. High frequency coils used in these various sensors are usually wound with enamel-insulated copper wires.
An eddy current proximity switch is one that uses the same principle as these various sensors. In addition to the eddy current type, the proximity switch includes a capacitance type and a magnetic type that captures changes in the DC magnetic field. It detects contacted conductive objects in a non-contact manner and outputs a switch signal. Higher response, longer life, and higher reliability than those that come in contact with the switch signal can be expected. In particular, the eddy current proximity switch can be discriminated between magnetic and non-magnetic objects to be measured, has the advantage of being easily miniaturized and hardly affected by an external magnetic field, and is expected to be used in industrial applications.
On the other hand, Japanese Utility Model Publication No. 42-1339 discloses that a high frequency gain can be improved when an enameled insulated wire having a ferromagnetic plating on the circumference of a copper wire is used for a high frequency ring winding. . Japanese Patent Laid-Open No. 62-219044 discloses an inductor made of a copper wire having a surface plated with a magnetic material.

FIG. 1 is a cross-sectional view of an embodiment of a wire used for a coil of a device to which the present invention is applied.
FIG. 2 is a diagram showing magnetic flux lines when a current is passed through the wire.
FIG. 3 is a diagram showing the strength of the magnetic field depending on the distance from the coil.
FIG. 4 is a circuit diagram showing an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied.
FIG. 5 is a diagram showing the positional relationship between the conductive object and the detection coil in the detection measurement apparatus of the above embodiment.
FIG. 6 is a graph comparing measured values of equivalent series resistance between a coil used in the detection measurement apparatus of the present invention and a conventional coil.
FIG. 7 is a graph comparing measured values of equivalent inductances of a coil used in the detection measurement apparatus of the present invention and a conventional coil.
FIG. 8 is a graph comparing the measured values of the high-frequency gain Q value between the coil used in the detection measurement apparatus of the present invention and a conventional coil.
FIG. 9 is a graph showing a change in resistance depending on the distance between the conductive object and the detection coil.
FIG. 10 is a graph showing the inductance depending on the distance between the conductive object and the detection coil.
FIG. 11 is a graph showing the high-frequency gain Q value according to the distance between the conductive object and the detection coil.
FIG. 12 is a graph showing the output voltage depending on the distance between the conductive object and the detection coil.
FIG. 13 is a graph showing the linearity of the output voltage characteristic depending on the distance between the conductive object and the detection coil.
FIG. 14 is a graph showing the sensitivity depending on the distance between the conductive object and the detection coil.
FIG. 15 is a cross-sectional view of the main part configuration of a flaw detection sensor which is an embodiment of the conductive object detection and measurement apparatus to which the present invention is applied.
FIG. 16 is a cross-sectional view of a high-frequency transformer to which the present invention is applied.
FIG. 17 is a block circuit diagram of a proximity switch to which the present invention is applied.
FIG. 18 is a cross-sectional view of a coil used in a proximity switch to which the present invention is applied.
FIG. 19 is a cross-sectional view of another embodiment of a wire used for a coil of a device to which the present invention is applied.

Explanation of symbols

1 is a copper wire, 3 is an iron layer, 5 is a nickel layer, 7 is an insulating layer, 8 is a magnetic flux line, 9 is a wire, 10 is a wire, 11 is a detection coil, 13 is a capacitor, 15 is a voltage dividing capacitor, 17 is An oscillator, 19 is a voltage measuring device, 20 is a conductive object, 23 is an iron core, 25 is a primary coil, 27 is a secondary coil, 30 is a crack, 32 is a wire, 33 is a fusion layer, 35 is an oscillation circuit, 36 Is a comparison circuit, 37 is an output circuit, 40 is a magnetic core, I _c is an excitation current, I _e is an eddy current, Φc · Φe is a magnetic flux, R (x) is an equivalent series resistance, L (x) is an inductance, and x is This is the distance between the conductive object and the detection coil.

Prior to the implementation of the invention, the inventor of the present invention conducted the following preliminary experiment and FEM (Finite Element Method) analysis using a computer, and obtained knowledge for completing the present invention.
First, a prototype coil and a conventional coil were created. As shown in detail in FIG. 1 (sectional view), the prototype coil wire 10 (wire used for the coil of the device of the present invention) is a magnetic layer on a core wire (outer diameter 90 μm) made of copper wire 1. An iron layer 3 and a nickel layer 5 are plated, and a polyurethane insulating layer 7 is coated on the outside thereof. The wire 10 was a coil having an inner diameter: 1.6 mm, an outer shape: 2.24 mm, an axial length: 0.63 mm, and a winding number: N = 26.
The conventional coil has the same number of turns and the same shape with a wire in which a polyurethane insulating layer is applied to the outer periphery of a copper wire (core wire outer diameter 90 μm).
(1) Magnetic flux lines when a current was passed through the coil were obtained by FEM analysis (software Maxwell). The analysis conditions were f = 1.4 MHz and I _c = 1 mA. As shown in FIG. 2A, the distribution of the magnetic flux lines 8 around the wire 10 of the prototype coil shown in FIG. 2A and the distribution of the magnetic flux lines 8 around the wire 9 of the conventional coil shown in FIG. It can be seen that the magnetic flux is less likely to enter the inside of the conducting wire than the conventional coil.
(2) The current density in the cross section of the wire when current was passed through the coil was obtained by FEM analysis. The trial coil wire 10 has a smaller current density distribution than the conventional coil wire 9. In the wire 10 of the prototype coil, the magnetic flux hardly enters the wire due to the shielding effect of the magnetic layer, but in the conventional coil, the magnetic flux enters the conductor, and an eddy current flows inside the wire due to the magnetic flux. The trial coil in which the magnetic flux is difficult to enter has a smaller current density distribution than the conventional coil. Therefore, since the resistance increases (proximity effect) due to bias in the current density distribution, the conventional coil has a higher resistance than the prototype coil.
(3) The strength of the magnetic field according to the distance from the coil was determined by FEM analysis. As shown in FIG. 3, it was found that when the distance r was increased, the magnetic field strength of the prototype coil was larger than that of the conventional coil.
The present invention has been made under the above-described knowledge, and provides a device including a high-inductance high-frequency coil that excites electromagnetic waves, and more specifically, has excellent detection sensitivity and a wide detection range. It is intended to provide a device for detecting and measuring conductive objects, proximity switches with high sensitivity and excellent operation reliability that are not affected by the surrounding magnetic field, motors and actuators with high power factor, and high-frequency transformers It is.
The conductive object detection and measurement apparatus of the present invention made to achieve the above object includes a coil (11) opposed to the conductive object (20) in a non-contact manner, and a voltage measuring device connected to the coil (11). (19), and the voltage measuring device measures the change in the output voltage of the coil (11) due to the eddy current flowing inside the conductive object (20) by high-frequency electromagnetic induction oscillated by the coil (11). An apparatus for detecting and measuring the conductive object (20) by measuring, wherein the wire (10) of the high-frequency oscillation coil (11) has a copper wire (1) covered with a magnetic layer (3.5). ).
The detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as detection of metals. That is, this detection measurement device means a metal detection sensor.
Similarly, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as the distance (x) between the conductive object (20) and the coil (11). That is, this detection and measurement device means a distance sensor to the conductive object (20).
Moreover, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as a scratch (30) inside the conductive object (20). In other words, this detection and measurement device means a flaw detection sensor in a conductive object.
The proximity switch of the present invention made to achieve the above object includes a coil (11), an oscillation circuit (35), a comparison circuit (36), and an output circuit (37) connected to the coil (11). An eddy current proximity switch that outputs an on / off signal from an output circuit (37) by an induced current flowing through the coil (11) when the conductive object (20) is approached. 10) is a copper wire (1) whose outer periphery is covered with a magnetic layer (3.5).
The high-frequency transformer of the present invention made to achieve the above object comprises at least a primary side coil (25) and a secondary side coil (27), and the wire (10) of the coil (25, 27) is an outer periphery. Is a copper wire (1) covered with a magnetic layer (3.5).
The magnetic layer on the outer periphery of the wire 10 of the coil (11, 25, 27) used in the detection and measurement device, proximity switch, or high-frequency transformer of the present invention is ferrite, iron, nickel, cobalt, Fe-N, Fe -X-N (X = Ta, Nb, Hf, etc.), Fe-X-O (X = Mg, Al, etc.), NiFe (Permalloy), CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, It can be implemented by at least one layer selected from soft magnetic materials such as CoFeB, CoNbZr, and Fe—Si.
The magnetic layer is preferably a plated iron or / and nickel layer.
Effect of the Invention The coil used in the detection and measurement device, proximity switch, or high-frequency transformer of the present invention uses a copper wire whose outer periphery is covered with a magnetic layer as a wire, and the inductance increases, so that the high-frequency gain Q value is increased. Will improve. Further, since the increase in resistance due to the proximity effect of the eddy current can be prevented by the shielding effect of the magnetic layer, the sensitivity of the detection and measurement device is improved, the sensitivity of the proximity switch is improved, and the efficiency of the high frequency transformer is improved.
Comparing the relationship between the distance from the coil of the detection measurement device to the conductive object to be detected and the output voltage of the coil, the output voltage of the coil used in the device of the present invention is a coil using a conventional copper wire. The output voltage is larger than the output voltage, the detection sensitivity is high, and the distance detection range is wide.

Ｑ（ｘ）＝ωＬ（ｘ）／Ｒ（ｘ） （２）
ｋ＝１＋Ｃ_ｐ／Ｃ_ｓ （３）
ここに、ｘ：測定対象である導電性物体から検出コイルまでの距離、Ｑ（ｘ）：距離ｘに依存するＱ値、Ｖ：励振電圧［Ｖ］、ω：角周波数［ｒａｄ／ｓ］、Ｌ（ｘ）：インダクタンス［Ｈ］、Ｒ（ｘ）：抵抗［Ω］、Ｃｐ：共振用コンデンサ１３、Ｃｓ：分圧用コンデンサ１５。
上記式から出力電圧ＶｏはコイルのＱ（ｘ）値とコンデンサ容量ＣｐおよびＣｓだけで表され、図１に示した並列共振を利用した検出測定装置の測定範囲の拡大や検出感度の向上には、コイルのＱ（ｘ）値、すなわち距離ｘに依存する高周波利得が影響することを示している。
そこで、実施例コイルと比較例コイルの周波数に対する等価直列抵抗Ｒ（ｘ＝∞）を測定し、図６に示した。実験では、実施例コイルのＲ（∞）は比較例コイルの約１．５倍となった。実施例コイルではＦｅ層とＮｉ層によって導線間の近接効果が軽減されるため、比較例コイルに比べ等価直列抵抗Ｒ（∞）が減少している。図６中に比較例コイルの表皮効果による抵抗の計算値を示した。
表皮効果による抵抗Ｒｓｅは、下式から算出した。

ここに、Ｒｄｃ：コイルの直流抵抗［Ω］、ｌ：巻始めから巻終りまでの導線の長さ［ｍ］、σ：導線の導電率［Ｓ／ｍ］、ｄ：導線の線径［ｍ］、ｒｉ：コイルの内径半径［ｍ］、ｒｅ：コイルの外形半径［ｍ］、δ：表皮厚さ［ｍ］、μｏ：導線の比透磁率、μｏ：真空の透磁率（４π×１０^−７）［Ｈ／ｍ］、ｂｅｒ：０次実数ケルビン関数、ｂｅｉ：０次複素数ケルビン関数。
さらに、図６は周波数に対する抵抗の増加が主に近接効果によって生じていることを示している。また共振周波数はいずれのコイルも１０．５ＭＨｚとなった。
実施例コイルと比較例コイルの周波数に対する等価直列インダクタンスを、図７に示した。周波数ｆ＝１００ｋＨｚ〜２ＭＨｚの範囲で実施例コイルと比較例コイルの等価直列インダクタンスＬ（∞）はそれぞれ４１μＨと３７μＨであり、実施例コイルは比較例コイルの１．１倍となった。
実施例コイルと比較例コイルの周波数ゲインＱ（∞）値を、測定し図８に示した。同図において、実施例コイルは、比較例コイルに比して、Ｑ（∞）値は１．７６倍となっている。この理由として、等価直列抵抗Ｒ（∞）が減少し、等価直列インダクタンスＬ（∞）が増加していることが挙げられる。
図９に示すように、実施例コイルと比較例コイルのインピーダンス

実施例コイルのインピーダンス特性が優れていることが明らかである。距離ｘが小さくなるにしたがって、測定対象である導電性物体により大きな磁束Φｃが作用して、導電性物体の渦電流損が増加する。これによりインピーダンス特性Ｒ（ｘ）が増加する。実施例コイルは、比較例コイルよりも大きな磁束Φｃが導電性物体に作用する（図３の試作コイル、従来のコイル参照）。したがって、距離ｘが小さくなるにしたがって実施例コイルのインピーダンスＲ（ｘ）は比較例コイルよりも急増する。
図１０に示すとおり、実施例コイルと比較例コイルは、夫々距離ｘに対してインダクタンスＬ（ｘ）は一定である。実施例コイルと比較例コイルのインダクタンスＬ（ｘ）はそれぞれ４０μＨと３６μＨであり、実施例コイルのインダクタンスＬ（ｘ）は比較例コイルの１．１倍である。磁性薄膜の効果によって実施例コイルのインダクタンスＬ（ｘ）は比較例コイルよりも大きいことが解かる。

ンダクタンスＬ（ｘ）も大きいために、図１１から分るように、高周波

図１２に実施例コイルと比較例コイルの出力電圧特性の比較を示した。また、同図中にそれぞれの出力電圧特性の最小二乗法を用いた近

Ｖ、試作コイルで８５０ｍＶとなり、実施例コイルが比較例コイルの

ΔＶ_ｏ＝Ｖ_ｏ（∞）−Ｖ_ｏ（０．１） ［Ｖ］
図１３に実施例コイルと比較例コイルの出力電圧特性の直線性の比較を示した。図１２に示した出力電圧特性を最小二乗法を用いて直線近似し、その近似値と実測値との誤差ｅ（ｘ）が±３％以内の範囲で直線性が保たれている距離の範囲Ｌを求めた。誤差ｅ（ｘ）は下式を用いて算出した。

ここに、Ｖｌ（ｘ）：近似直線の電圧［Ｖ］。
出力電力の直線性がε（ｘ）＝±３％以内に保たれている範囲は、表１に示すとおり、実施例コイルと比較例コイルでそれぞれ０．１〜２．２ｍｍと０．１〜１．６ｍｍである。すなわち実施例コイルと比較例コイルの直線範囲Ｌはそれぞれ２．１ｍｍと１．５ｍｍである。また、コイルの外径寸法Ｄに対する直線範囲Ｌ／Ｄは、実施例コイルと比較例コイルでそれぞれ０．５８と０．３３となった。コイルの平均半径ｒａに対する直線範囲Ｌ／ｒａは、実施例コイルと比較例コイルでそれぞれ１．２３と０．８７となった。Ｌ／Ｄ、Ｌ／ｒａともに実施例コイルが比較例コイルの約１．４倍となった。なお、いずれのコイルもＤ＝４．５４ｍｍ、ｒａ＝１．７３ｍｍである。したがって、実施例コイルは、比較例コイルと比較して、直線性に優れており、導電性物体検出測定装置の距離検出範囲の拡大が実現されている。

図１４に実施例コイルと比較例コイルを用いた場合における導電性物体検出測定装置の検出感度の比較を示した。ｎ番目の測定点におけ

実施例コイルで最大３１０Ｖ／ｍとなり、１．５倍になった。すべての距離において実施例コイルの方が比較例コイルより高感度となった。したがって、実施例コイルは比較例コイルと比較して距離検出感度の向上が実現されている。
以上の結果から、導電性物体検出測定装置のコイルに磁性めっき線を用いることで、従来の銅線と比較して距離測定範囲の拡大と距離検出感度の向上が可能である。
上記の実施例では、装置の検出コイルから導電性物体までの距離を測定できる距離センサとしての例を説明したが、同一の構成で金属類など導電性物体の有無そのものを調べる金属探知センサとしての利用もでき、実施例コイルを使用した装置が比較例コイルを使用した装置よりも高感度であるし、探査範囲も広くなることが明らかである。
また、図１５には上記検出測定装置を傷探知センサとして利用した実施例の概略構成の断面が示してある。この図に示すとおり、測定対象である導電性物体２０にクラック３０がある場合、導電性物体２０の内部に流れる渦電流がクラック３０の存在により変化する。その結果、検出コイル１１の共振出力が変わり、クラック３０の有無を検出できる。このような傷探知センサとして利用した場合においても、実施例コイルを使用した装置が比較例コイルを使用した装置よりも高感度であるし、探査範囲も広くなる。
図１６には本発明の高周波変圧器の一実施例の断面が示してあり、鉄芯２３に一次コイル２５と、二次コイル２７が巻かれている。これらのコイル２５・２７のそれぞれの線材が外周を磁性体層で覆った銅線になっている。一次コイル２５に入力した高周波電圧は変圧され、二次コイル２７から出力される。
高周波変圧器の例としてＤＣ−ＤＣコンバータに用いられているパルス変圧器がある。一次コイル２５には外部の電子回路（図示していない）から高周波の電流が流される。図６の実施例コイルと比較例コイルの周波数に対する直列等価抵抗Ｒ（∞）の比較に示したように、実施例コイルの抵抗Ｒは、比較例コイルと比較して小さい。すなわち、高周波変圧器において、銅線の外周を磁性体薄膜で覆った磁性めっき線を用いたコイルで構成することで、コイルに発生する銅損を低減することができ、高周波変圧器は高効率になる。
この実施例では鉄心を有する変圧器で説明したが、鉄心がない空心形変圧器でもよい。実施例コイルは、比較例コイルよりも多くの磁束を作用させる、すなわち、磁束をより遠くに飛ばすことができるから、実施例コイルを用いた空心トランスも高性能化を実現できる。
図１７は、本発明の近接スイッチの構成であり渦電流形である。コイル１１、コイル１１に接続して発振回路３５と比較回路３６と出力回路３７とを有している。発振回路３５は、コイルとコイルに並列に接続されたコンデンサから構成される共振回路に励振電流を供給しており、共振回路の電圧（変位）が出力されている。比較回路３６は、予め設定された電圧（以下、設定変位）と共振回路の出力をＯＰアンプを用いて比較することで、変位が設定変位未満の場合と変位が設定変位以上の場合に対応した電圧を出力する。出力回路３７は、比較回路３６の出力から、変位が設定変位未満の場合には０Ｖを出力し、変位が設定変位以上の場合には５Ｖを出力する。
コイル１１は、図１８に示すとおり、フェライトなどの軟磁性体から構成されるコア４０に、図１に示した線材１０を巻いた構成となっている。なお、コイル１１はコアのない空心コイルであってもよい。
上記の渦電流形近接スイッチで導電性物体２０の接近でコイルに流れる誘導電流に起因して出力回路からオン・オフの二値の出力電圧を得ている。
このような構成としたことで、コイル１１の交流抵抗が上昇することを抑制し、インダクタンスが増加し、磁束を導電性物体２０に多く作用させることができるので、コイル１１から導電性物体２０までの感度距離を拡大し、コイル１１の小形化が実現できる。
尚、図１に示した線材１０の断面図では、線材１０は、銅線１に鉄層３とニッケル層５がメッキされているが、ＮｉＦｅやフェライトなどの高透磁率と高抵抗率をもつ磁性体をめっきなどの工程で形成してもよい。
図２０には、本発明を適用する機器のコイルに使用される線材であって、図１に示した例とは別な実施例の線材の断面図が示してある。この例の線材３２は、銅線１からなる芯線に、磁性体層である鉄層３とニッケル層５がメッキされ、その外側にポリウレタンの絶縁層７があり、さらに外側に熱可塑性樹脂からなる融着層が設けてある。この実施例の線材３２は、加熱しながら磁性コアに直接巻線を行うことができ、また融着層がとけて導線どうしが結合する。Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these examples.
FIG. 4 shows a circuit diagram of an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied. The conductive object detection and measurement apparatus shown in the figure is a distance sensor from the detection coil of the apparatus to a conductive object, a metal detection sensor that checks for the presence of metals, and a flaw detection sensor that detects the presence or absence of cracks in a conductive object. Available.
As shown in FIG. 4, the detection coil (high-frequency oscillation coil) 11 is opposed to the conductive object 20 in a non-contact manner. The detection coil 11 has an equivalent series inductance L (x) and an equivalent series resistance R (x) characteristic. The detection coil 11 forms a resonant circuit in parallel with the capacitor 13. An AC voltmeter 19 is connected to the resonance circuit. The detection coil 11 is connected to an oscillator 17 via a voltage dividing capacitor 15 for limiting the current.
The wire of the detection coil 11 used in the conductive object detection and measurement apparatus of the present invention is a copper wire whose outer periphery is covered with a magnetic layer. As shown in detail in FIG. 1 (cross-sectional view), a wire 10 according to an embodiment of the present invention has a core wire made of copper wire 1 plated with an iron layer 3 and a nickel layer 5 which are magnetic layers, and polyurethane on the outside thereof. Insulating layer 7 is applied. The outer diameter of the core wire of the copper wire 1 is 90 μm, the outer shape of the iron layer 3 is 92 μm (layer thickness 1 μm), and the outer shape of the nickel layer 5 is 92.1 μm (layer thickness 0.05 μm). The nickel layer is provided in order to make it easy to attach the solder.
This wire 10 is wound around a bobbin made of acrylic resin with a diameter of 3.36 mm, wound 102 times, with an axial length of 2.15 mm, and has a coil outer diameter of 4.54 mm (coil inner diameter 3.36 mm, coil inner / outer differential thickness 0. 59 mm, coil average radius = 1.975 mm) Example detection coil 11 (hereinafter, also referred to as example coil).
For comparison purposes, a coil with the same number of turns is used as a conventional high-frequency oscillation coil (hereinafter referred to as a comparative example coil) in which a polyurethane insulating layer is coated on the outer periphery of a copper wire (core wire outer diameter 90 μm).
The conductive object 20 to be measured is chrome molybdenum steel (SCM440) which is a magnetic material in this embodiment.
In the above detection / measurement apparatus, when the detection / measurement target is the distance x between the conductive object 20 and the coil 11, the following operation is performed. The operation and performance evaluation of the device will be described below.
When an excitation voltage V (excitation frequency f = 1.4 MHz) is applied from the oscillator 17 of the apparatus and an excitation current Ic is passed through the detection coil 11, a magnetic flux Φc is generated as shown in FIG. When the magnetic flux Φc acts on the conductive object 20, an eddy current Ie flows through the conductive object 20 due to electromagnetic induction to generate a magnetic flux Φe. Since the magnetic flux acting on the conductive object 20 changes according to the distance x from the detection coil 11 to the conductive object 20, the eddy current Ie flowing through the conductive object 20 changes, and as a result, the impedance of the detection coil 11 changes. Change. This change in impedance is converted into an output voltage Vo by a parallel resonant circuit. The actually measured value of the resonance frequency of the output voltage Vo actually measured at this time was f _o = 10.5 MHz. The output voltage Vo is expressed by the following equation.

Q (x) = ωL (x) / R (x) (2)
k = 1 + C _p / C _s (3)
Where x: distance from the conductive object to be measured to the detection coil, Q (x): Q value depending on the distance x, V: excitation voltage [V], ω: angular frequency [rad / s], L (x): Inductance [H], R (x): Resistance [Ω], Cp: Resonance capacitor 13, Cs: Voltage division capacitor 15.
From the above equation, the output voltage Vo is expressed only by the Q (x) value of the coil and the capacitor capacities Cp and Cs. For the purpose of expanding the measurement range and improving the detection sensitivity of the detection measurement device using the parallel resonance shown in FIG. This shows that the Q (x) value of the coil, that is, the high frequency gain depending on the distance x is affected.
Therefore, the equivalent series resistance R (x = ∞) with respect to the frequencies of the example coil and the comparative example coil was measured and shown in FIG. In the experiment, R (∞) of the example coil was about 1.5 times that of the comparative example coil. In the example coil, the proximity effect between the conductors is reduced by the Fe layer and the Ni layer, so that the equivalent series resistance R (∞) is reduced as compared with the comparative example coil. FIG. 6 shows a calculated value of resistance due to the skin effect of the comparative example coil.
The resistance Rse due to the skin effect was calculated from the following equation.

Where, Rdc: DC resistance [Ω] of the coil, l: length of the conducting wire from the beginning to the end of winding [m], σ: conductivity of the conducting wire [S / m], d: wire diameter of the conducting wire [m] ], Ri: inner radius of the coil [m], re: outer radius of the coil [m], δ: skin thickness [m], μo: relative permeability of the conductor, μo: permeability of vacuum (4π × 10 ^{− 7} ) [H / m], ber: 0th order real Kelvin function, bei: 0th order complex Kelvin function.
Furthermore, FIG. 6 shows that the increase in resistance with respect to frequency is mainly caused by the proximity effect. The resonance frequency was 10.5 MHz for all coils.
FIG. 7 shows the equivalent series inductance with respect to the frequencies of the example coil and the comparative example coil. In the frequency range of f = 100 kHz to 2 MHz, the equivalent series inductance L (∞) of the example coil and the comparative example coil was 41 μH and 37 μH, respectively, and the example coil was 1.1 times that of the comparative example coil.
The frequency gain Q (∞) values of the example coil and the comparative example coil were measured and shown in FIG. In the figure, the example coil has a Q (∞) value of 1.76 times that of the comparative example coil. This is because the equivalent series resistance R (∞) decreases and the equivalent series inductance L (∞) increases.
As shown in FIG. 9, the impedance of the example coil and the comparative example coil

It is clear that the impedance characteristics of the example coil are excellent. As the distance x decreases, a large magnetic flux Φc acts on the conductive object to be measured, and the eddy current loss of the conductive object increases. As a result, the impedance characteristic R (x) increases. In the example coil, a magnetic flux Φc larger than that in the comparative example coil acts on the conductive object (see the prototype coil in FIG. 3 and the conventional coil). Therefore, as the distance x decreases, the impedance R (x) of the example coil increases more rapidly than the comparative example coil.
As shown in FIG. 10, the inductance and the comparative example coil have constant inductance L (x) with respect to the distance x. The inductance L (x) of the example coil and the comparative example coil are 40 μH and 36 μH, respectively, and the inductance L (x) of the example coil is 1.1 times that of the comparative example coil. It can be seen that the inductance L (x) of the example coil is larger than that of the comparative example coil due to the effect of the magnetic thin film.

Since the conductance L (x) is also large, as shown in FIG.

FIG. 12 shows a comparison of output voltage characteristics between the example coil and the comparative example coil. Also, in the figure, each output voltage characteristic is calculated using the least square method.

V, 850 mV for the prototype coil, and the example coil is a comparative example coil

ΔV _o = V _o (∞) −V _o (0.1) [V]
FIG. 13 shows a comparison of the linearity of the output voltage characteristics of the example coil and the comparative example coil. The output voltage characteristic shown in FIG. 12 is linearly approximated using the least square method, and the distance range where linearity is maintained within an error e (x) within ± 3% of the approximate value and the actual measurement value. L was determined. The error e (x) was calculated using the following equation.

Here, Vl (x): voltage of approximate line [V].
As shown in Table 1, the ranges in which the linearity of the output power is kept within ε (x) = ± 3% are 0.1 to 2.2 mm and 0.1 to 0.1 mm for the example coil and the comparative coil, respectively. 1.6 mm. That is, the linear ranges L of the example coil and the comparative example coil are 2.1 mm and 1.5 mm, respectively. The linear range L / D with respect to the outer diameter D of the coil was 0.58 and 0.33 for the example coil and the comparative coil, respectively. The linear range L / ra with respect to the average radius ra of the coil was 1.23 and 0.87 for the example coil and the comparative example coil, respectively. In both L / D and L / ra, the coil of the example was about 1.4 times the coil of the comparative example. Note that in all the coils, D = 4.54 mm and ra = 1.73 mm. Therefore, the example coil is excellent in linearity as compared with the comparative example coil, and the distance detection range of the conductive object detection and measurement apparatus is expanded.

FIG. 14 shows a comparison of detection sensitivities of the conductive object detection and measurement apparatus when the example coil and the comparative example coil are used. At the nth measurement point

The maximum value of the example coil was 310 V / m, which was 1.5 times higher. The example coil was more sensitive than the comparative coil at all distances. Therefore, the example coil achieves improved distance detection sensitivity compared to the comparative example coil.
From the above results, by using a magnetic plating wire for the coil of the conductive object detection and measurement device, it is possible to expand the distance measurement range and improve the distance detection sensitivity as compared with the conventional copper wire.
In the above embodiment, an example of a distance sensor that can measure the distance from the detection coil of the apparatus to a conductive object has been described. However, as a metal detection sensor that checks the presence or absence of a conductive object such as metals with the same configuration. It is obvious that the apparatus using the example coil is more sensitive than the apparatus using the comparative example coil, and the exploration range is widened.
Further, FIG. 15 shows a cross section of a schematic configuration of an embodiment in which the detection and measurement apparatus is used as a flaw detection sensor. As shown in this figure, when the conductive object 20 to be measured has a crack 30, the eddy current flowing inside the conductive object 20 changes due to the presence of the crack 30. As a result, the resonance output of the detection coil 11 changes and the presence or absence of the crack 30 can be detected. Even when used as such a flaw detection sensor, the device using the coil of the embodiment is more sensitive than the device using the coil of the comparative example, and the search range is widened.
FIG. 16 shows a cross section of an embodiment of the high-frequency transformer of the present invention, in which a primary coil 25 and a secondary coil 27 are wound around an iron core 23. Each of the wires of the coils 25 and 27 is a copper wire whose outer periphery is covered with a magnetic layer. The high frequency voltage input to the primary coil 25 is transformed and output from the secondary coil 27.
An example of a high-frequency transformer is a pulse transformer used in a DC-DC converter. The primary coil 25 is supplied with a high-frequency current from an external electronic circuit (not shown). As shown in the comparison of the series equivalent resistance R (∞) with respect to the frequency of the example coil and the comparative example coil in FIG. 6, the resistance R of the example coil is smaller than that of the comparative example coil. That is, in a high-frequency transformer, the copper loss generated in the coil can be reduced by configuring the coil using a magnetic plating wire in which the outer periphery of the copper wire is covered with a magnetic thin film. become.
In this embodiment, the transformer having an iron core has been described, but an air core type transformer without an iron core may be used. Since the embodiment coil allows a larger amount of magnetic flux to act than the comparative example coil, that is, the magnetic flux can be dissipated further away, the air core transformer using the embodiment coil can also achieve high performance.
FIG. 17 shows the configuration of the proximity switch according to the present invention, which is an eddy current type. An oscillation circuit 35, a comparison circuit 36, and an output circuit 37 are connected to the coil 11 and the coil 11. The oscillation circuit 35 supplies an excitation current to a resonance circuit including a coil and a capacitor connected in parallel to the coil, and a voltage (displacement) of the resonance circuit is output. The comparison circuit 36 compares the preset voltage (hereinafter, set displacement) with the output of the resonance circuit using an OP amplifier, and copes with the case where the displacement is less than the set displacement and the case where the displacement is greater than the set displacement. Output voltage. From the output of the comparison circuit 36, the output circuit 37 outputs 0V when the displacement is less than the set displacement, and outputs 5V when the displacement is greater than or equal to the set displacement.
As shown in FIG. 18, the coil 11 has a configuration in which the wire 10 shown in FIG. 1 is wound around a core 40 made of a soft magnetic material such as ferrite. The coil 11 may be an air core coil without a core.
With the above eddy current type proximity switch, a binary output voltage of ON / OFF is obtained from the output circuit due to the induced current flowing in the coil when the conductive object 20 approaches.
By adopting such a configuration, it is possible to suppress an increase in the AC resistance of the coil 11, to increase the inductance, and to cause a large amount of magnetic flux to act on the conductive object 20, so from the coil 11 to the conductive object 20. Thus, the coil 11 can be miniaturized.
In the cross-sectional view of the wire 10 shown in FIG. 1, the wire 10 has a copper wire 1 plated with an iron layer 3 and a nickel layer 5, but has a high magnetic permeability and high resistivity such as NiFe and ferrite. The magnetic body may be formed by a process such as plating.
FIG. 20 shows a cross-sectional view of a wire rod of an embodiment different from the example shown in FIG. 1 that is a wire rod used in a coil of a device to which the present invention is applied. The wire 32 in this example has a core wire made of copper wire 1 plated with an iron layer 3 and a nickel layer 5 which are magnetic layers, a polyurethane insulating layer 7 on the outside, and a thermoplastic resin on the outside. A fusing layer is provided. The wire 32 of this embodiment can be directly wound around the magnetic core while being heated, and the fused layer is melted to join the conductors.

[0005]
The bias of the current density distribution is smaller than that of the material 9. In the wire 10 of the prototype coil, the magnetic flux hardly enters the wire due to the shielding effect of the magnetic layer, but in the conventional coil, the magnetic flux enters the conductor, and an eddy current flows inside the wire due to the magnetic flux. The trial coil in which the magnetic flux is difficult to enter has a smaller current density distribution than the conventional coil. Therefore, since the resistance increases (proximity effect) due to bias in the current density distribution, the conventional coil has a higher resistance than the prototype coil.
(3) The strength of the magnetic field according to the distance from the coil was determined by FEM analysis. As shown in FIG. 3, it was found that when the distance r was increased, the magnetic field strength of the prototype coil was larger than that of the conventional coil.
The present invention has been made under the above-described knowledge, and provides a device including a high-inductance high-frequency coil that excites electromagnetic waves, and more specifically, has excellent detection sensitivity and a wide detection range. It is intended to provide a device for detecting and measuring conductive objects, proximity switches with high sensitivity and excellent operation reliability that are not affected by the surrounding magnetic field, motors and actuators with high power factor, and high-frequency transformers It is.
The conductive object detection and measurement apparatus of the present invention made to achieve the above object includes a coil (11) opposed to the conductive object (20) in a non-contact manner, and a voltage measuring device connected to the coil (11). (19), and the voltage measuring device measures the change in the output voltage of the coil (11) due to the eddy current flowing inside the conductive object (20) by high-frequency electromagnetic induction oscillated by the coil (11). An apparatus for detecting and measuring the conductive object (20) by measuring, wherein the wire (10) of the high-frequency oscillation coil (11) is plated with an iron layer and a nickel layer on a core wire made of copper wire, A polyurethane insulating layer is coated on the outside. A fusion layer made of a thermoplastic resin may be provided outside the polyurethane insulating layer. Further, the wires may be bonded to each other by the fusion layer.
The detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as detection of metals. In other words, this detection measurement device is a metal detection sensor.

[0006]
It means sa.
Similarly, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as the distance (x) between the conductive object (20) and the coil (11). That is, this detection and measurement device means a distance sensor to the conductive object (20).
Moreover, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as a scratch (30) inside the conductive object (20). In other words, this detection and measurement device means a flaw detection sensor in a conductive object.
The proximity switch of the present invention made to achieve the above object includes a coil (11), an oscillation circuit (35), a comparison circuit (36), and an output circuit (37) connected to the coil (11). An eddy current proximity switch that outputs an on / off signal from an output circuit (37) by an induced current flowing through the coil (11) when the conductive object (20) is approached. 10) is characterized in that an iron layer and a nickel layer are plated on a core wire made of a copper wire, and an insulating layer of polyurethane is applied on the outside thereof. A fusion layer made of a thermoplastic resin may be provided outside the polyurethane insulating layer. Further, the wires may be bonded to each other by the fusion layer.
The high-frequency transformer of the present invention made to achieve the above object includes at least a primary side coil (25) and a secondary side coil (27), and the wire (10) of the coil (25, 27) includes: A core wire made of copper wire is plated with an iron layer and a nickel layer, and a polyurethane insulating layer is coated on the outside thereof. A fusion layer made of a thermoplastic resin may be provided outside the polyurethane insulating layer. Further, the wires may be bonded to each other by the fusion layer.
The magnetic material layer on the outer periphery of the wire 10 of the coil (11, 25, 27) used in the detection and measurement device, proximity switch, or high-frequency transformer of the present invention is composed of ferrite, nickel, cobalt, Fe in addition to the above-described iron. -N, Fe-XN (X = Ta, Nb, Hf, etc.), Fe-X-O (X = Mg, Al, etc.), NiFe (permalloy), CoFe, CoNiFe, CoFeB, FeP, It can be implemented with at least one layer selected from soft magnetic materials such as NiFeP, CoNiFeMoC, CoFeB, CoNbZr, and Fe—Si.

[0007]
【The invention's effect】
The coil used in the detection and measurement apparatus, proximity switch, or high-frequency transformer of the present invention uses a copper wire whose outer periphery is covered with a magnetic layer as a wire, and the inductance increases, so that the high-frequency gain Q value is improved. . Further, since the increase in resistance due to the proximity effect of the eddy current can be prevented by the shielding effect of the magnetic layer, the sensitivity of the detection and measurement device is improved, the sensitivity of the proximity switch is improved, and the efficiency of the high frequency transformer is improved.
Comparing the relationship between the distance from the coil of the detection measurement device to the conductive object to be detected and the output voltage of the coil, the output voltage of the coil used in the device of the present invention is a coil using a conventional copper wire. The output voltage is larger than the output voltage, the detection sensitivity is high, and the distance detection range is wide.
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these examples.
FIG. 4 shows a circuit diagram of an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied. The conductive object detection and measurement apparatus shown in the figure is a distance sensor from the detection coil of the apparatus to a conductive object, a metal detection sensor that checks for the presence of metals, and a flaw detection sensor that detects the presence or absence of cracks in a conductive object. Available.
As shown in FIG. 4, the detection coil (high-frequency oscillation coil) 11 is opposed to the conductive object 20 in a non-contact manner. The detection coil 11 has an equivalent series inductance L (x) and an equivalent series resistance R (x) characteristic. detection

[0015]
Excitation current is supplied to a resonance circuit composed of connected capacitors, and the voltage (displacement) of the resonance circuit is output. The comparison circuit 36 compares the preset voltage (hereinafter, set displacement) with the output of the resonance circuit using an OP amplifier, and copes with the case where the displacement is less than the set displacement and the case where the displacement is greater than the set displacement. Output voltage. From the output of the comparison circuit 36, the output circuit 37 outputs 0V when the displacement is less than the set displacement, and outputs 5V when the displacement is greater than or equal to the set displacement.
As shown in FIG. 18, the coil 11 has a configuration in which the wire 10 shown in FIG. 1 is wound around a core 40 made of a soft magnetic material such as ferrite. The coil 11 may be an air core coil without a core.
With the above eddy current type proximity switch, a binary output voltage of ON / OFF is obtained from the output circuit due to the induced current flowing in the coil when the conductive object 20 approaches.
By adopting such a configuration, it is possible to suppress an increase in the AC resistance of the coil 11, to increase the inductance, and to cause a large amount of magnetic flux to act on the conductive object 20, so from the coil 11 to the conductive object 20. Thus, the coil 11 can be miniaturized.
In the cross-sectional view of the wire 10 shown in FIG. 1, the wire 10 has a copper wire 1 plated with an iron layer 3 and a nickel layer 5, but has a high magnetic permeability and high resistivity such as NiFe and ferrite. The magnetic body may be formed by a process such as plating.
FIG. 19 shows a cross-sectional view of a wire rod of an embodiment different from the example shown in FIG. 1 which is a wire rod used in a coil of a device to which the present invention is applied. The wire 32 in this example has a core wire made of copper wire 1 plated with an iron layer 3 and a nickel layer 5 which are magnetic layers, a polyurethane insulating layer 7 on the outside, and a thermoplastic resin on the outside. A fusing layer is provided. this

【００３３】
【数２】

【００３４】
【数３】

ここに、ｘ：測定対象である導電性物体から検出コイルまでの距離、Ｑ(ｘ)：距離ｘに依存するＱ値、Ｖ：励振電圧[Ｖ]、 ω：角周波数[ｒａｄ/ｓ]、Ｌ(ｘ):インダクタンス[Ｈ]、Ｒ(ｘ):抵抗[Ω]、Ｃｐ：共振用コンデンサ１３、Ｃs：分圧用コンデンサ１５。
【００３５】
上記式から出力電圧ＶoはコイルのＱ(ｘ)値とコンデンサ容量ＣｐおよびＣsだけで表され、図１に示した並列共振を利用した検出測定装置の測定範囲の拡大や検出感度の向上には、コイルのＱ(ｘ)値、すなわち距離ｘに依存する高周波利得が影響することを示している。
【００３６】
そこで、実施例コイルと比較例コイルの周波数に対する等価直列抵抗Ｒ(ｘ＝∞)を測定し、図６に示した。実験では、実施例コイルのＲ(∞)は比較例コイルの約１．５倍となった。実施例コイルではＦｅ層とＮｉ層によって導線間の近接効果が軽減されるため、比較例コイルに比べ等価直列抵抗Ｒ(∞)が減少している。図６中に比較例コイルの表皮効果による抵抗の計算値を示した。
【００３７】
表皮効果による抵抗Ｒseは、下式から算出した。
【００３８】
【数４】

【００３９】
【数５】

【００４０】
【数６】

【００４１】
【数７】

【００４２】
【数８】

ここに、Ｒdc：コイルの直流抵抗[Ω]、ｌ：巻始めから巻終りまでの導線の長さ[ｍ]、σ：導線の導電率[Ｓ/ｍ]、ｄ：導線の線径[ｍ]、ｒi：コイルの内径半径[ｍ]、ｒｅ：コイルの外形半径[ｍ]、δ：表皮厚さ[ｍ]、μo：導線の比透磁率、μo：真空の透磁率（４π×１０^−７）[Ｈ/ｍ]、ｂｅｒ：０次実数ケルビン関数、ｂｅｉ：０次複素数ケルビン関数。
【００４３】
さらに、図６は周波数に対する抵抗の増加が主に近接効果によって生じていることを示している。また共振周波数はいずれのコイルも１０．５ＭＨｚとなった。
【００４４】
実施例コイルと比較例コイルの周波数に対する等価直列インダクタンスを、図７に示した。周波数ｆ＝１００ｋＨｚ〜２ＭＨｚの範囲で実施例コイルと比較例コイルの等価直列インダクタンスＬ(∞)はそれぞれ４１μＨと３７μＨであり、実施例コイルは比較例コイルの１．１倍となった。
【００４５】
実施例コイルと比較例コイルの周波数ゲインＱ(∞)値を、測定し図８に示した。同図において、実施例コイルは、比較例コイルに比して、Ｑ(∞)値は１．７６倍となっている。この理由として、等価直列抵抗Ｒ(∞)が減少し、等価直列インダクタンスＬ(∞)が増加していることが挙げられる。
【００４６】
図９に示すように、実施例コイルと比較例コイルのインピーダンス特性Ｒ(ｘ)の変化量ΔＲは、それぞれ３１Ωと３８Ωであり、比較例コイルのインピーダンス変化量ΔＲは実施例コイルの１．２倍あり、実施例コイルのインピーダンス特性が優れていることが明らかである。距離ｘが小さくなるにしたがって、測定対象である導電性物体により大きな磁束Φcが作用して、導電性物体の渦電流損が増加する。これによりインピーダンス特性Ｒ(ｘ)が増加する。実施例コイルは、比較例コイルよりも大きな磁束Φcが導電性物体に作用する（図３の試作コイル、従来のコイル参照）。したがって、距離ｘが小さくなるにしたがって実施例コイルのインピーダンスＲ(ｘ)は比較例コイルよりも急増する。
【００４７】
図１０に示すとおり、実施例コイルと比較例コイルは、夫々距離ｘに対してインダクタンスＬ(ｘ)は一定である。実施例コイルと比較例コイルのインダクタンスＬ(ｘ)はそれぞれ４０μＨと３６μＨであり、実施例コイルのインダクタンスＬ(ｘ)は比較例コイルの１．１倍である。磁性薄膜の効果によって実施例コイルのインダクタンスＬ(ｘ)は比較例コイルよりも大きいことが解かる。
【００４８】
また、実施例コイルはインピーダンス変化量ΔＲが大きく、かつインダクタンスＬ(ｘ)も大きいために、図１１から分るように、高周波利得Ｑ(ｘ)値の変化量ΔＱは、比較例コイルの約２倍である。
【００４９】
図１２に実施例コイルと比較例コイルの出力電圧特性の比較を示した。また、同図中にそれぞれの出力電圧特性の最小二乗法を用いた近似直線を示した。出力電圧の変化量ΔＶoは従来のコイルで４３０ｍＶ、試作コイルで８５０ｍＶとなり、実施例コイルが比較例コイルの約２倍となった。変化量ΔＶoは下式から算出した。
【００５０】
【数９】

図１３に実施例コイルと比較例コイルの出力電圧特性の直線性の比較を示した。図１２に示した出力電圧特性を最小二乗法を用いて直線近似し、その近似値と実測値との誤差ｅ(ｘ)が±３％以内の範囲で直線性が保たれている距離の範囲Ｌを求めた。誤差ｅ(ｘ)は下式を用いて算出した。
【００５１】
【数１０】

ここに、Ｖl(ｘ)：近似直線の電圧[Ｖ]。
【００５２】
出力電力の直線性がε(ｘ)＝±３％以内に保たれている範囲は、表１に示すとおり、実施例コイルと比較例コイルでそれぞれ０.１〜２.２ｍｍと０.１〜１.６ｍｍである。すなわち実施例コイルと比較例コイルの直線範囲Ｌはそれぞれ２.１ｍｍと１.５ｍｍである。また、コイルの外径寸法Ｄに対する直線範囲_Ｌ/Ｄは、実施例コイルと比較例コイルでそれぞれ０.５８と０.３３となった。コイルの平均半径ｒaに対する直線範囲_Ｌ/ｒaは、実施例コイルと比較例コイルでそれぞれ１.２３と０.８７となった。Ｌ/Ｄ、_Ｌ/ｒaともに実施例コイルが比較例コイルの約１.４倍となった。なお、いずれのコイルもＤ＝４.５４ｍｍ、ｒa＝１.７３ｍｍである。したがって、実施例コイルは、比較例コイルと比較して、直線性に優れており、導電性物体検出測定装置の距離検出範囲の拡大が実現されている。
【００５３】
【表１】

図１４に実施例コイルと比較例コイルを用いた場合における導電性物体検出測定装置の検出感度の比較を示した。ｎ番目の測定点における検出感度ΔＶo’(ｘn)/Δｘnは下式を用いて算出した。
【００５４】
【数１１】

同図より検出感度ΔVo’/Δｘは、比較例コイルで最大１９５Ｖ/ｍ、実施例コイルで最大３１０Ｖ/ｍとなり、１.５倍になった。すべての距離において実施例コイルの方が比較例コイルより高感度となった。したがって、実施例コイルは比較例コイルと比較して距離検出感度の向上が実現されている。
【００５５】
以上の結果から、導電性物体検出測定装置のコイルに磁性めっき線を用いることで、従来の銅線と比較して距離測定範囲の拡大と距離検出感度の向上が可能である。
【００５６】
上記の実施例では、装置の検出コイルから導電性物体までの距離を測定できる距離センサとしての例を説明したが、同一の構成で金属類など導電性物体の有無そのものを調べる金属探知センサとしての利用もでき、実施例コイルを使用した装置が比較例コイルを使用した装置よりも高感度であるし、探査範囲も広くなることが明らかである。
【００５７】
また、図１５には上記検出測定装置を傷探知センサとして利用した実施例の概略構成の断面が示してある。この図に示すとおり、測定対象である導電性物体２０にクラック３０がある場合、導電性物体２０の内部に流れる渦電流がクラック３０の存在により変化する。その結果、検出コイル１１の共振出力が変わり、クラック３０の有無を検出できる。このような傷探知センサとして利用した場合においても、実施例コイルを使用した装置が比較例コイルを使用した装置よりも高感度であるし、探査範囲も広くなる。
【００５８】
図１６には本発明の高周波変圧器の一実施例の断面が示してあり、鉄芯２３に一次コイル２５と、二次コイル２７が巻かれている。これらのコイル２５・２７のそれぞれの線材が外周を磁性体層で覆った銅線になっている。一次コイル２５に入力した高周波電圧は変圧され、二次コイル２７から出力される。
【００５９】
高周波変圧器の例としてＤＣ−ＤＣコンバータに用いられているパルス変圧器がある。一次コイル２５には外部の電子回路（図示していない）から高周波の電流が流される。図６の実施例コイルと比較例コイルの周波数に対する直列等価抵抗Ｒ(∞)の比較に示したように、実施例コイルの抵抗Ｒは、比較例コイルと比較して小さい。すなわち、高周波変圧器において、銅線の外周を磁性体薄膜で覆った磁性めっき線を用いたコイルで構成することで、コイルに発生する銅損を低減することができ、高周波変圧器は高効率になる。
【００６０】
この実施例では鉄心を有する変圧器で説明したが、鉄心がない空心形変圧器でもよい。実施例コイルは、比較例コイルよりも多くの磁束を作用させる、すなわち、磁束をより遠くに飛ばすことができるから、実施例コイルを用いた空心トランスも高性能化を実現できる。
【００６１】
図１７は、本発明の近接スイッチの構成であり渦電流形である。コイル１１、コイル１１に接続して発振回路３５と比較回路３６と出力回路３７とを有している。発振回路３５は、コイルとコイルに並列に接続されたコンデンサから構成される共振回路に励振電流を供給しており、共振回路の電圧（変位）が出力されている。比較回路３６は、予め設定された電圧（以下、設定変位）と共振回路の出力をOPアンプを用いて比較することで、変位が設定変位未満の場合と変位が設定変位以上の場合に対応した電圧を出力する。出力回路３７は、比較回路３６の出力から、変位が設定変位未満の場合には0Vを出力し、変位が設定変位以上の場合には5Vを出力する。
【００６２】
コイル１１は、図１８に示すとおり、フェライトなどの軟磁性体から構成されるコア４０に、図１に示した線材１０を巻いた構成となっている。なお、コイル１１はコアのない空心コイルであってもよい。
【００６３】
上記の渦電流形近接スイッチで導電性物体２０の接近でコイルに流れる誘導電流に起因して出力回路からオン・オフの二値の出力電圧を得ている。
【００６４】
このような構成としたことで、コイル１１の交流抵抗が上昇することを抑制し、インダクタンスが増加し、磁束を導電性物体２０に多く作用させることができるので、コイル１１から導電性物体２０までの感度距離を拡大し、コイル１１の小形化が実現できる。
【００６５】
尚、図１に示した線材１０の断面図では、線材１０は、銅線１に鉄層３とニッケル層５がメッキされているが、ＮｉＦｅやフェライトなどの高透磁率と高抵抗率をもつ磁性体をめっきなどの工程で形成してもよい。
【００６６】
図２０には、本発明を適用する機器のコイルに使用される線材であって、図１に示した例とは別な実施例の線材の断面図が示してある。この例の線材３２は、銅線１からなる芯線に、磁性体層である鉄層３とニッケル層５がメッキされ、その外側にポリウレタンの絶縁層７があり、さらに外側に熱可塑性樹脂からなる融着層が設けてある。この実施例の線材３２は、加熱しながら磁性コアに直接巻線を行うことができ、また融着層がとけて導線どうしが結合する。
【図面の簡単な説明】
【００６７】
【図１】
図１は、本発明を適用する機器のコイルに使用される線材の一実施例の断面図である。
【図２】
図２は、線材に電流を流したときの磁束線を示す図である。
【図３】
図３は、コイルからの距離による磁界の強さを示す図である。
【図４】
図４は、本発明を適用する導電性物体検出測定装置の一実施例を示す回路図である。
【図５】
図５は、前記実施例の検出測定装置における導電性物体と検出コイルの位置関係を示す図である。
【図６】
図６は、本発明の検出測定装置に使用するコイルと、従来のコイルとの等価直列抵抗の実測値を比較したグラフである。
【図７】
図７は、本発明の検出測定装置に使用するコイルと、従来のコイルとの等価インダクタンスの実測値を比較したグラフである。
【図８】
図８は、本発明の検出測定装置に使用するコイルと、従来のコイルとの高周波利得Ｑ値の実測値を比較したグラフである。
【図９】
図９は、導電性物体と検出コイルとの距離による抵抗変化を示すグラフである。
【図１０】
図１０は、導電性物体と検出コイルとの距離によるインダクタンスを示すグラフである。
【図１１】
図１１は、導電性物体と検出コイルとの距離による高周波利得Ｑ値を示すグラフである。
【図１２】
図１２は、導電性物体と検出コイルとの距離による出力電圧を示すグラフである。
【図１３】
図１３は、導電性物体と検出コイルとの距離による出力電圧特性の直線性を示すグラフである。
【図１４】
図１４は、導電性物体と検出コイルとの距離による感度を示すグラフである。
【図１５】
図１５は、本発明を適用する導電性物体検出測定装置の一実施例である傷探知センサの要部構成断面図である。
【図１６】
図１６は、本発明を適用する高周波変圧器の断面図である。
【図１７】
図１７は、本発明を適用する近接スイッチのブロック回路図である。
【図１８】
図１８は、本発明を適用する近接スイッチに使用されるコイルの断面図である。
【図１９】
図１９は、本発明を適用する機器のコイルに使用される線材の別な実施例の断面図である。
【符号の説明】
【００６８】
１は銅線、３は鉄層、５はニッケル層、７は絶縁層、８は磁束線、９は線材、１０は線材、１１は検出コイル、１３はコンデンサ、１５は分圧用コンデンサ、１７は発振器、１９は電圧測定器、２０は導電性物体、２３は鉄芯、２５は一次コイル、２７は二次コイル、３０はクラック、３２は線材、３３は融着層、３５は発振回路、３６は比較回路、３７は出力回路、４０は磁性コア、Ｉ_ｃは励振電流、Ｉ_ｅは渦電流、Φc・Φeは磁束、Ｒ(ｘ)は等価直列抵抗、Ｌ(ｘ)はインダクタンス、ｘは導電性物体と検出コイルとの距離である。 [Document Name] Description [Title of Invention] Equipment with High Frequency Coil [Technical Field]
[0001]
The present invention relates to a device including a high-frequency coil that excites electromagnetic waves, specifically to a device for detecting and measuring a conductive object, a proximity switch, and a high-frequency transformer including a high-frequency coil.
[Background]
[0002]
It is known that when an electromagnetic wave is oscillated from a high-frequency coil, an electromagnetic induction current flows through a conductive object in the magnetic field. Various sensors have been developed using the induced eddy current generated by the high-frequency coil. For example, Patent Document 1 discloses a gap sensor for preventing laser processing head impact. Patent Document 2 discloses a non-contact gap measurement for a wood chip refiner, Patent Document 3 measures a distance of a driving shaft of a cutter used for excavation work, Patent Document 4 detects a thickness of an image recording paper, Patent document 5 discloses various sensors such as determination of a metal material, and patent document 6 such as a magnetic bearing. High frequency coils used in these various sensors are usually wound with enamel-insulated copper wires.
[0003]
An eddy current proximity switch is one that uses the same principle as these various sensors. In addition to the eddy current type, the proximity switch includes a capacitance type and a magnetic type that captures changes in the DC magnetic field. It detects contacted conductive objects in a non-contact manner and outputs a switch signal. Higher response, longer life, and higher reliability than those that come in contact with the switch signal can be expected. In particular, the eddy current proximity switch can be discriminated between magnetic and non-magnetic objects to be measured, has the advantage of being easily miniaturized and hardly affected by an external magnetic field, and is expected to be used in industrial applications.
[0004]
On the other hand, Patent Document 7 discloses that a high frequency gain can be improved when an enameled insulated wire having a ferromagnetic plating on the circumference of a copper wire is used for a high frequency ring winding. Patent Document 8 describes an inductor made of a copper wire having a surface plated with a magnetic material.
[0005]
[Patent Document 1] JP-A-9-277070 [Patent Document 2] JP-A-7-83606 [Patent Document 3] JP-A 2002-4773 [Patent Document 4] JP-A-11-165430 [Patent Document 3] [Patent Document 5] JP-A-8-184579 [Patent Document 6] JP-A-2-201101 [Patent Document 7] Japanese Utility Model Publication No. 42-1339 [Patent Document 8] JP-A-62-211904 Disclosure]
[0006]
Prior to the implementation of the invention, the inventor of the present invention performed the following preliminary experiment and FEM (Finite Element Method) analysis by a computer, and obtained knowledge for completing the present invention.
[0007]
First, a prototype coil and a conventional coil were created. As shown in detail in FIG. 1 (sectional view), the prototype coil wire 10 (wire used for the coil of the device of the present invention) is a magnetic layer on a core wire (outer diameter 90 μm) made of copper wire 1. An iron layer 3 and a nickel layer 5 are plated, and a polyurethane insulating layer 7 is coated on the outside thereof. The wire 10 was a coil having an inner diameter: 1.6 mm, an outer shape: 2.24 mm, an axial length: 0.63 mm, and a winding number: N = 26.
[0008]
The conventional coil has the same number of turns and the same shape with a wire in which a polyurethane insulating layer is applied to the outer periphery of a copper wire (core wire outer diameter 90 μm).
[0009]
(1) Magnetic flux lines when current was passed through the coil were obtained by FEM analysis (software Maxwell). The analysis conditions were f = 1.4 MHz and I _c = 1 mA. As shown in FIG. 2A, the distribution of the magnetic flux lines 8 around the wire 10 of the prototype coil shown in FIG. 2A and the distribution of the magnetic flux lines 8 around the wire 9 of the conventional coil shown in FIG. It can be seen that the magnetic flux is less likely to enter the inside of the conducting wire than the conventional coil.
[0010]
(2) The current density in the cross section of the wire when current was passed through the coil was obtained by FEM analysis. The trial coil wire 10 has a smaller current density distribution than the conventional coil wire 9. In the wire 10 of the prototype coil, the magnetic flux hardly enters the wire due to the shielding effect of the magnetic layer, but in the conventional coil, the magnetic flux enters the conductor, and an eddy current flows inside the wire due to the magnetic flux. The trial coil in which the magnetic flux is difficult to enter has a smaller current density distribution than the conventional coil. Therefore, since the resistance increases (proximity effect) due to bias in the current density distribution, the conventional coil has a higher resistance than the prototype coil.
[0011]
(3) The strength of the magnetic field according to the distance from the coil was determined by FEM analysis. As shown in FIG. 3, it was found that when the distance r was increased, the magnetic field strength of the prototype coil was larger than that of the conventional coil.
[Problems to be solved by the invention]
[0012]
The present invention has been made under the above-described knowledge, and provides a device including a high-inductance high-frequency coil that excites electromagnetic waves, and more specifically, has excellent detection sensitivity and a wide detection range. It is intended to provide a device for detecting and measuring conductive objects, proximity switches with high sensitivity and excellent operation reliability that are not affected by the surrounding magnetic field, motors and actuators with high power factor, and high-frequency transformers It is.
[Means for Solving the Problems]
[0013]
The conductive object detection and measurement apparatus of the present invention made to achieve the above object includes a coil (11) opposed to the conductive object (20) in a non-contact manner, and a voltage measuring device connected to the coil (11). (19), and the voltage measuring device measures the change in the output voltage of the coil (11) due to the eddy current flowing inside the conductive object (20) by high-frequency electromagnetic induction oscillated by the coil (11). An apparatus for detecting and measuring the conductive object (20) by measuring, wherein the wire (10) of the high-frequency oscillation coil (11) has a copper wire (1) covered with a magnetic layer (3.5). ).
[0014]
The detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as detection of metals. That is, this detection measurement device means a metal detection sensor.
[0015]
Similarly, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as the distance (x) between the conductive object (20) and the coil (11). That is, this detection and measurement device means a distance sensor to the conductive object (20).
[0016]
Moreover, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as a scratch (30) inside the conductive object (20). In other words, this detection and measurement device means a flaw detection sensor in a conductive object.
[0017]
The proximity switch of the present invention made to achieve the above object includes a coil (11), an oscillation circuit (35), a comparison circuit (36), and an output circuit (37) connected to the coil (11). An eddy current proximity switch that outputs an on / off signal from an output circuit (37) by an induced current flowing through the coil (11) when the conductive object (20) is approached. 10) is a copper wire (1) whose outer periphery is covered with a magnetic layer (3.5).
[0018]
The high-frequency transformer of the present invention made to achieve the above object comprises at least a primary side coil (25) and a secondary side coil (27), and the wire (10) of the coil (25, 27) is an outer periphery. Is a copper wire (1) covered with a magnetic layer (3.5).
[0019]
The magnetic body layer on the outer periphery of the wire 10 of the coil (11, 25, 27) used in the detection and measurement device, proximity switch, or high-frequency transformer of the present invention is ferrite, iron, nickel, cobalt, Fe-N, Fe -XN (X = Ta, Nb, Hf, etc.), Fe-XO (X = Mg, Al, etc.), NiFe (Permalloy), CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr, It can be implemented by at least one layer selected from soft magnetic materials such as Fe-Si.
[0020]
The magnetic layer is preferably a plated iron or / and nickel layer.
【The invention's effect】
[0021]
The coil used in the detection and measurement apparatus, proximity switch, or high-frequency transformer of the present invention uses a copper wire whose outer periphery is covered with a magnetic layer as a wire, and the inductance increases, so that the high-frequency gain Q value is improved. . Further, since the increase in resistance due to the proximity effect of the eddy current can be prevented by the shielding effect of the magnetic layer, the sensitivity of the detection and measurement device is improved, the sensitivity of the proximity switch is improved, and the efficiency of the high frequency transformer is improved.
[0022]
Comparing the relationship between the distance from the coil of the detection measurement device to the conductive object to be detected and the output voltage of the coil, the output voltage of the coil used in the device of the present invention is a coil using a conventional copper wire. The output voltage is larger than the output voltage, the detection sensitivity is high, and the distance detection range is wide.
BEST MODE FOR CARRYING OUT THE INVENTION
[0023]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these examples.
【Example】
[0024]
FIG. 4 shows a circuit diagram of an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied. The conductive object detection and measurement apparatus shown in the figure is a distance sensor from the detection coil of the apparatus to a conductive object, a metal detection sensor that checks for the presence of metals, and a flaw detection sensor that detects the presence or absence of cracks in a conductive object. Available.
[0025]
As shown in FIG. 4, the detection coil (high-frequency oscillation coil) 11 is opposed to the conductive object 20 in a non-contact manner. The detection coil 11 has an equivalent series inductance L (x) and an equivalent series resistance R (x) characteristic. The detection coil 11 forms a resonant circuit in parallel with the capacitor 13. An AC voltmeter 19 is connected to the resonance circuit. The detection coil 11 is connected to an oscillator 17 via a voltage dividing capacitor 15 for limiting the current.
[0026]
The wire of the detection coil 11 used in the conductive object detection and measurement apparatus of the present invention is a copper wire whose outer periphery is covered with a magnetic layer. As shown in detail in FIG. 1 (cross-sectional view), a wire 10 according to an embodiment of the present invention has a core wire made of copper wire 1 plated with an iron layer 3 and a nickel layer 5 which are magnetic layers, and polyurethane on the outside thereof. Insulating layer 7 is applied. The outer diameter of the copper wire 1 is 90 μm, the outer shape of the iron layer 3 is 92 μm (layer thickness 1 μm), and the outer shape of the nickel layer 5 is 92.1 μm (layer thickness 0.05 μm). The nickel layer is provided in order to make it easy to attach the solder.
[0027]
This wire 10 is wound around a bobbin made of acrylic resin with a diameter of 3.36 mm to have a winding number of 102 and an axial length of 2.15 mm. The outer diameter of the coil is 4.54 mm (the inner diameter of the coil is 3.36 mm, the difference between the inner and outer diameters of the coil is 0. 59 mm, coil average radius = 1.975 mm) Example detection coil 11 (hereinafter also referred to as example coil).
[0028]
For comparison purposes, a coil with the same number of turns is used as a conventional high-frequency oscillation coil (hereinafter referred to as a comparative example coil) in which a polyurethane insulating layer is coated on the outer periphery of a copper wire (core wire outer diameter 90 μm).
[0029]
The conductive object 20 to be measured is chrome molybdenum steel (SCM440) which is a magnetic material in this embodiment.
[0030]
In the above detection / measurement apparatus, when the detection / measurement target is the distance x between the conductive object 20 and the coil 11, the following operation is performed. The operation and performance evaluation of the device will be described below.
[0031]
When an excitation voltage V (excitation frequency f = 1.4 MHz) is applied from the oscillator 17 of the apparatus and an excitation current Ic is supplied to the detection coil 11, a magnetic flux Φc is generated as shown in FIG. When the magnetic flux Φc acts on the conductive object 20, an eddy current Ie flows through the conductive object 20 due to electromagnetic induction to generate a magnetic flux Φe. Since the magnetic flux acting on the conductive object 20 changes according to the distance x from the detection coil 11 to the conductive object 20, the eddy current Ie flowing through the conductive object 20 changes. As a result, the impedance of the detection coil 11 changes. Change. This change in impedance is converted into an output voltage Vo by a parallel resonance circuit. Measured values of the resonance frequency at this time actually measured output voltage Vo was _f o = 10.5 MHz. The output voltage Vo is expressed by the following equation.
[0032]
[Expression 1]

[0033]
[Expression 2]

[0034]
[Equation 3]

Where x: distance from the conductive object to be measured to the detection coil, Q (x): Q value depending on the distance x, V: excitation voltage [V], ω: angular frequency [rad / s], L (x): Inductance [H], R (x): Resistance [Ω], Cp: Resonance capacitor 13, Cs: Voltage division capacitor 15.
[0035]
From the above equation, the output voltage Vo is expressed only by the Q (x) value of the coil and the capacitor capacities Cp and Cs. For the purpose of expanding the measurement range and improving the detection sensitivity of the detection and measurement apparatus using the parallel resonance shown in FIG. This shows that the Q (x) value of the coil, that is, the high frequency gain depending on the distance x is affected.
[0036]
Therefore, the equivalent series resistance R (x = ∞) with respect to the frequency of the example coil and the comparative example coil was measured and shown in FIG. In the experiment, R (∞) of the example coil was about 1.5 times that of the comparative example coil. In the example coil, the proximity effect between the conductors is reduced by the Fe layer and the Ni layer, so that the equivalent series resistance R (∞) is reduced as compared with the comparative example coil. FIG. 6 shows a calculated value of resistance due to the skin effect of the comparative example coil.
[0037]
The resistance Rse due to the skin effect was calculated from the following equation.
[0038]
[Expression 4]

[0039]
[Equation 5]

[0040]
[Formula 6]

[0041]
[Expression 7]

[0042]
[Equation 8]

Where, Rdc: DC resistance [Ω] of the coil, l: length of the conducting wire from the beginning to the end of winding [m], σ: conductivity of the conducting wire [S / m], d: wire diameter of the conducting wire [m] , Ri: inner radius of coil [m], re: outer radius of coil [m], δ: skin thickness [m], μo: relative permeability of conductor, μo: permeability of vacuum (4π × 10 ^{− 7} ) [H / m], ber: 0th order real Kelvin function, bei: 0th order complex Kelvin function.
[0043]
Furthermore, FIG. 6 shows that the increase in resistance with respect to frequency is mainly caused by the proximity effect. The resonance frequency was 10.5 MHz for all coils.
[0044]
FIG. 7 shows the equivalent series inductance with respect to the frequencies of the example coil and the comparative example coil. In the frequency range of f = 100 kHz to 2 MHz, the equivalent series inductance L (∞) of the example coil and the comparative example coil was 41 μH and 37 μH, respectively, and the example coil was 1.1 times that of the comparative example coil.
[0045]
The frequency gain Q (∞) values of the example coil and the comparative example coil were measured and shown in FIG. In the figure, the example coil has a Q (∞) value of 1.76 times that of the comparative example coil. This is because the equivalent series resistance R (∞) decreases and the equivalent series inductance L (∞) increases.
[0046]
As shown in FIG. 9, the amount of change ΔR of the impedance characteristic R (x) of the example coil and the comparative example coil is 31Ω and 38Ω, respectively, and the amount of impedance change ΔR of the comparative example coil is 1.2 of the example coil. It is clear that the impedance characteristics of the example coil are excellent. As the distance x decreases, a larger magnetic flux Φc acts on the conductive object to be measured, and the eddy current loss of the conductive object increases. As a result, the impedance characteristic R (x) increases. In the example coil, a magnetic flux Φc larger than that in the comparative example coil acts on the conductive object (see the prototype coil in FIG. 3 and the conventional coil). Therefore, as the distance x decreases, the impedance R (x) of the example coil increases more rapidly than the comparative example coil.
[0047]
As shown in FIG. 10, the inductance coil L and the comparative example coil have constant inductance L (x) with respect to the distance x. The inductance L (x) of the example coil and the comparative example coil is 40 μH and 36 μH, respectively, and the inductance L (x) of the example coil is 1.1 times that of the comparative example coil. It can be seen that the inductance L (x) of the example coil is larger than that of the comparative example coil due to the effect of the magnetic thin film.
[0048]
Further, since the embodiment coil has a large impedance change amount ΔR and a large inductance L (x), as can be seen from FIG. 11, the change amount ΔQ of the high frequency gain Q (x) value is about the same as that of the comparative example coil. 2 times.
[0049]
FIG. 12 shows a comparison of output voltage characteristics between the example coil and the comparative example coil. In addition, approximate straight lines using the least square method of each output voltage characteristic are shown in FIG. The change amount ΔVo of the output voltage was 430 mV for the conventional coil and 850 mV for the prototype coil, and the example coil was about twice that of the comparative example coil. The change amount ΔVo was calculated from the following equation.
[0050]
[Equation 9]

FIG. 13 shows a comparison of the linearity of the output voltage characteristics of the example coil and the comparative example coil. The output voltage characteristics shown in FIG. 12 are linearly approximated using the least square method, and the distance range where linearity is maintained within an error e (x) within ± 3% of the approximate value and the actual measurement value. L was determined. The error e (x) was calculated using the following equation.
[0051]
[Expression 10]

Here, Vl (x): voltage [V] of the approximate straight line.
[0052]
As shown in Table 1, the range in which the linearity of the output power is kept within ε (x) = ± 3% is 0.1 to 2.2 mm and 0.1 to 0.1 for the example coil and the comparative example coil, respectively. 1.6 mm. That is, the linear ranges L of the example coil and the comparative example coil are 2.1 mm and 1.5 mm, respectively. The linear range _L / D with respect to the outer diameter D of the coil was 0.58 and 0.33 for the example coil and the comparative example coil, respectively. The linear range _L / ra with respect to the average radius ra of the coil was 1.23 and 0.87 for the example coil and the comparative coil, respectively. In both L / D and _L / ra, the coil of the example was about 1.4 times the coil of the comparative example. In all of the coils, D = 4.54 mm and ra = 1.73 mm. Therefore, the example coil is excellent in linearity as compared with the comparative example coil, and the distance detection range of the conductive object detection and measurement apparatus is expanded.
[0053]
[Table 1]

FIG. 14 shows a comparison of detection sensitivities of the conductive object detection and measurement apparatus when the example coil and the comparative example coil are used. The detection sensitivity ΔVo ′ (xn) / Δxn at the nth measurement point was calculated using the following equation.
[0054]
[Expression 11]

From the figure, the detection sensitivity ΔVo ′ / Δx is 1.5 times as large as 195 V / m at the maximum for the comparative example coil and 310 V / m at the maximum for the example coil. The example coil was more sensitive than the comparative coil at all distances. Therefore, the example coil achieves improved distance detection sensitivity compared to the comparative example coil.
[0055]
From the above results, by using a magnetic plating wire for the coil of the conductive object detection and measurement device, it is possible to expand the distance measurement range and improve the distance detection sensitivity as compared with the conventional copper wire.
[0056]
In the above embodiment, an example of a distance sensor that can measure the distance from the detection coil of the apparatus to a conductive object has been described. However, as a metal detection sensor that checks the presence or absence of a conductive object such as metals with the same configuration. It is obvious that the apparatus using the example coil is more sensitive than the apparatus using the comparative example coil, and the exploration range is widened.
[0057]
Further, FIG. 15 shows a cross section of a schematic configuration of an embodiment in which the detection and measurement apparatus is used as a flaw detection sensor. As shown in this figure, when the conductive object 20 to be measured has a crack 30, the eddy current flowing inside the conductive object 20 changes due to the presence of the crack 30. As a result, the resonance output of the detection coil 11 changes and the presence or absence of the crack 30 can be detected. Even when used as such a flaw detection sensor, the device using the coil of the embodiment is more sensitive than the device using the coil of the comparative example, and the search range is widened.
[0058]
FIG. 16 shows a cross section of an embodiment of the high-frequency transformer of the present invention, in which a primary coil 25 and a secondary coil 27 are wound around an iron core 23. Each of the wires of the coils 25 and 27 is a copper wire whose outer periphery is covered with a magnetic layer. The high frequency voltage input to the primary coil 25 is transformed and output from the secondary coil 27.
[0059]
An example of a high-frequency transformer is a pulse transformer used in a DC-DC converter. The primary coil 25 is supplied with a high-frequency current from an external electronic circuit (not shown). As shown in the comparison of the series equivalent resistance R (∞) with respect to the frequency of the example coil and the comparative example coil in FIG. 6, the resistance R of the example coil is smaller than that of the comparative example coil. That is, in a high-frequency transformer, the copper loss generated in the coil can be reduced by configuring the coil using a magnetic plating wire in which the outer periphery of the copper wire is covered with a magnetic thin film. become.
[0060]
In this embodiment, the transformer having an iron core has been described, but an air core type transformer without an iron core may be used. Since the embodiment coil allows a larger amount of magnetic flux to act than the comparative example coil, that is, the magnetic flux can be dissipated further away, the air core transformer using the embodiment coil can also achieve high performance.
[0061]
FIG. 17 shows the configuration of the proximity switch according to the present invention, which is an eddy current type. An oscillation circuit 35, a comparison circuit 36, and an output circuit 37 are connected to the coil 11 and the coil 11. The oscillation circuit 35 supplies an excitation current to a resonance circuit including a coil and a capacitor connected in parallel to the coil, and a voltage (displacement) of the resonance circuit is output. The comparison circuit 36 compares the preset voltage (hereinafter, set displacement) with the output of the resonance circuit using an OP amplifier, so that the case where the displacement is less than the set displacement and the case where the displacement is greater than the set displacement are supported. Output voltage. From the output of the comparison circuit 36, the output circuit 37 outputs 0V when the displacement is less than the set displacement, and outputs 5V when the displacement is greater than or equal to the set displacement.
[0062]
As shown in FIG. 18, the coil 11 has a configuration in which the wire 10 shown in FIG. 1 is wound around a core 40 made of a soft magnetic material such as ferrite. The coil 11 may be an air core coil without a core.
[0063]
With the above eddy current type proximity switch, a binary output voltage of ON / OFF is obtained from the output circuit due to the induced current flowing in the coil when the conductive object 20 approaches.
[0064]
By adopting such a configuration, it is possible to suppress an increase in the AC resistance of the coil 11, to increase the inductance, and to cause a large amount of magnetic flux to act on the conductive object 20, so from the coil 11 to the conductive object 20. Thus, the coil 11 can be miniaturized.
[0065]
In the cross-sectional view of the wire 10 shown in FIG. 1, the wire 10 has a copper wire 1 plated with an iron layer 3 and a nickel layer 5, but has a high magnetic permeability and high resistivity such as NiFe and ferrite. The magnetic body may be formed by a process such as plating.
[0066]
FIG. 20 shows a cross-sectional view of a wire rod of an embodiment different from the example shown in FIG. 1 that is a wire rod used in a coil of a device to which the present invention is applied. The wire 32 in this example has a core wire made of copper wire 1 plated with an iron layer 3 and a nickel layer 5 which are magnetic layers, a polyurethane insulating layer 7 on the outside, and a thermoplastic resin on the outside. A fusing layer is provided. The wire 32 of this embodiment can be directly wound around the magnetic core while being heated, and the fused layer is melted to join the conductors.
[Brief description of the drawings]
[0067]
[Figure 1]
FIG. 1 is a cross-sectional view of an embodiment of a wire used for a coil of a device to which the present invention is applied.
[Figure 2]
FIG. 2 is a diagram showing magnetic flux lines when a current is passed through the wire.
[Fig. 3]
FIG. 3 is a diagram showing the strength of the magnetic field depending on the distance from the coil.
[Fig. 4]
FIG. 4 is a circuit diagram showing an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied.
[Figure 5]
FIG. 5 is a diagram showing the positional relationship between the conductive object and the detection coil in the detection measurement apparatus of the above embodiment.
[Fig. 6]
FIG. 6 is a graph comparing measured values of equivalent series resistance between a coil used in the detection measurement apparatus of the present invention and a conventional coil.
[Fig. 7]
FIG. 7 is a graph comparing measured values of equivalent inductances of a coil used in the detection measurement apparatus of the present invention and a conventional coil.
[Fig. 8]
FIG. 8 is a graph comparing the measured values of the high-frequency gain Q value between the coil used in the detection measurement apparatus of the present invention and a conventional coil.
FIG. 9
FIG. 9 is a graph showing a change in resistance depending on the distance between the conductive object and the detection coil.
FIG. 10
FIG. 10 is a graph showing the inductance depending on the distance between the conductive object and the detection coil.
FIG. 11
FIG. 11 is a graph showing the high-frequency gain Q value according to the distance between the conductive object and the detection coil.
FIG.
FIG. 12 is a graph showing the output voltage depending on the distance between the conductive object and the detection coil.
FIG. 13
FIG. 13 is a graph showing the linearity of the output voltage characteristic depending on the distance between the conductive object and the detection coil.
FIG. 14
FIG. 14 is a graph showing the sensitivity depending on the distance between the conductive object and the detection coil.
FIG. 15
FIG. 15 is a cross-sectional view of the main part configuration of a flaw detection sensor which is an embodiment of the conductive object detection and measurement apparatus to which the present invention is applied.
FIG. 16
FIG. 16 is a cross-sectional view of a high-frequency transformer to which the present invention is applied.
FIG. 17
FIG. 17 is a block circuit diagram of a proximity switch to which the present invention is applied.
FIG. 18
FIG. 18 is a cross-sectional view of a coil used in a proximity switch to which the present invention is applied.
FIG. 19
FIG. 19 is a cross-sectional view of another embodiment of a wire used for a coil of a device to which the present invention is applied.
[Explanation of symbols]
[0068]
1 is a copper wire, 3 is an iron layer, 5 is a nickel layer, 7 is an insulating layer, 8 is a magnetic flux line, 9 is a wire, 10 is a wire, 11 is a detection coil, 13 is a capacitor, 15 is a voltage dividing capacitor, 17 is An oscillator, 19 is a voltage measuring device, 20 is a conductive object, 23 is an iron core, 25 is a primary coil, 27 is a secondary coil, 30 is a crack, 32 is a wire, 33 is a fusion layer, 35 is an oscillation circuit, 36 comparison circuit 37 output circuit, 40 is a magnetic core, I _c is the excitation current, I _e is the eddy current, .PHI.c · .PHI.e magnetic flux, R (x) is the equivalent series resistance, L (x) is an inductance, x is This is the distance between the conductive object and the detection coil.

Claims (12)

  An output of the coil due to an eddy current flowing inside the conductive object by high-frequency electromagnetic induction generated by the coil having a coil that contacts the conductive object in a non-contact manner and a voltage measuring device connected to the coil An apparatus for detecting and measuring the conductive object by measuring a voltage change with the measuring device, wherein the wire of the high-frequency oscillation coil is a copper wire whose outer periphery is covered with a magnetic layer. Object detection measurement device.   The magnetic layer is made of ferrite, iron, nickel, cobalt, Fe-N, Fe-XN (X = Ta, Nb, or Hf), Fe-X-O (X = Mg, or Al), NiFe, 2. The conductive object detection and measurement apparatus according to claim 1, which is at least one layer selected from CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr, and Fe—Si.   2. The conductive object detection and measurement apparatus according to claim 1, wherein the magnetic layer is a plated iron or / and nickel layer.   The conductive object detection / measurement apparatus according to claim 1, wherein the measurement object of the conductive object is detection of a metal.   The conductive object detection and measurement apparatus according to claim 1, wherein the measurement object of the conductive object is an interval distance between the conductive object and the coil.   The conductive object detection / measurement apparatus according to claim 1, wherein the measurement object of the conductive object is a flaw inside the conductive object.   An eddy current type proximity switch that has an oscillation circuit, a comparison circuit, and an output circuit connected to the coil, and outputs an on / off signal from the output circuit due to an induced current flowing through the coil when a conductive object approaches. A proximity switch, wherein the wire of the coil is a copper wire whose outer periphery is covered with a magnetic layer.   The magnetic layer is made of ferrite, iron, nickel, cobalt, Fe-N, Fe-XN (X = Ta, Nb, or Hf), Fe-X-O (X = Mg, or Al), NiFe, 8. The proximity switch according to claim 7, wherein the proximity switch is at least one layer selected from CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr, and Fe-Si.   9. The proximity switch according to claim 8, wherein the magnetic layer is a plated iron or / and nickel layer.   A high frequency transformer comprising at least a primary side coil and a secondary side coil, wherein the wire of the coil is a copper wire whose outer periphery is covered with a magnetic layer.   The magnetic layer is made of iron, nickel, cobalt, ferrite, Fe-N, Fe-XN (X = Ta, Nb, or Hf), Fe-X-O (X = Mg, or Al), NiFe, The high-frequency transformer according to claim 10, wherein the high-frequency transformer is at least one layer selected from CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr, and Fe-Si.   The high-frequency transformer according to claim 10, wherein the magnetic layer is a plated iron or / and nickel layer.

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