JP2009264992A - Induction type proximity sensor - Google Patents

Induction type proximity sensor Download PDF

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JP2009264992A
JP2009264992A JP2008116617A JP2008116617A JP2009264992A JP 2009264992 A JP2009264992 A JP 2009264992A JP 2008116617 A JP2008116617 A JP 2008116617A JP 2008116617 A JP2008116617 A JP 2008116617A JP 2009264992 A JP2009264992 A JP 2009264992A
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coil
core
proximity sensor
circuit
shaped core
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Tsutomu Mizuno
勉 水野
Tsutomu Tadane
勉 唯根
Shigeharu Matsumoto
重治 松本
Yoshio Kishi
芳男 岸
Katsuhiko Nakatani
克彦 中谷
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Shinshu University NUC
Koyo Electronics Industries Co Ltd
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Shinshu University NUC
Koyo Electronics Industries Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction type proximity sensor having a large ratio L/D which is a ratio of a detection distance L to an outer diameter D of a core. <P>SOLUTION: The induction type proximity sensor includes a U-shaped core 1, a coil 2 as an oscillation element wound around the U-shaped core 1, an oscillation circuit 43 including the coil 2, a comparison circuit 45 for generating a binary ON or OFF signal on the basis of a Q value of the coil, and an output circuit 46 for amplifying an output of the comparison circuit. The U-shaped core 1 suppresses increase of a coil resistance due to a proximity effect so that more fluxes act on a detection object 3 far away, thereby increasing a detection distance. The proximity sensor includes a plurality of independent coils 21, 22 wound around the U-shaped core 1, thereby a highly sensitive, highly precise operation can be performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

この発明は誘導型近接センサの検出距離および検出感度の向上に関するものである。この近接センサには、誘導型近接スイッチを含む。   The present invention relates to an improvement in detection distance and detection sensitivity of an inductive proximity sensor. This proximity sensor includes an inductive proximity switch.

誘導型近接センサは、工作機械、搬送機械、食品機械などのあらゆる産業分野で利用されている。近接センサ実装時には検出対象（検出物）との距離、平行度などが検出感度および精度に大きく影響すること、自動車、搬送業界などで、誘導型近接センサを適用ないし応用する分野では、検出対象が近接センサの検出面に接触すると、破損や故障の原因となりやすいことから、検出距離の長距離化が要求されてきている。   Inductive proximity sensors are used in all industrial fields such as machine tools, transport machines, and food machines. When a proximity sensor is mounted, the distance to the detection target (detection object), parallelism, etc. will greatly affect the detection sensitivity and accuracy, and in the fields where the inductive proximity sensor is applied or applied in the automobile and transportation industries, the detection target is Since contact with the detection surface of the proximity sensor tends to cause damage or failure, it has been required to increase the detection distance.

従来の誘導型近接センサの構造例を図５に示す。この誘導型近接センサは、円筒状ポットコア４１を備える。この円筒状ポットコア４１は、中央円柱状の中央脚４１ａと、この中央脚４１ａの外周を円筒状に取り囲む有底円筒状の外周脚４１ｂと、から構成されている。この中央脚４１ａに巻回される形態でその外周と外周脚４１ｂの内周との間にコイル４２が内蔵されている。そして、このコイル４２に対して、発振回路４３から周波数（ｆ）の励振電流（Ｉｃ（ｆ））を供給することで、磁束（Φ）が発生する。この磁束（Φ）が検出対象４４に作用すると電磁誘導の法則により検出対象４４に渦電流（Ｉｅ）が流れて磁束（Φｅ）が生ずる。検出対象４４とコイル４２との間の変位に応じて磁束量が変化するために、検出対象４４に流れる渦電流（Ｉｅ）が変わり、その結果としてコイル４２の抵抗（Ｒ）とインダクタンス（Ｌ）および（Ｑ値）が変化する。この変化を比較回路４５において基準と比較することにより、（Ｑ値）に基づいて二値のＯＮまたはＯＦＦ信号を発生させて、出力回路４６をとおしてその信号に対応した出力電圧（Ｖｏ）として出力させる。この出力電圧（Ｖｏ）のレベルがＯＮまたはＯＦＦに切り替わる変位が検出距離（Ｌ）である（特許文献１、２参照）。   An example of the structure of a conventional inductive proximity sensor is shown in FIG. This inductive proximity sensor includes a cylindrical pot core 41. The cylindrical pot core 41 includes a central columnar central leg 41a and a bottomed cylindrical outer peripheral leg 41b that surrounds the outer periphery of the central leg 41a in a cylindrical shape. A coil 42 is incorporated between the outer periphery of the central leg 41a and the inner periphery of the outer peripheral leg 41b. A magnetic flux (Φ) is generated by supplying an excitation current (Ic (f)) having a frequency (f) from the oscillation circuit 43 to the coil 42. When this magnetic flux (Φ) acts on the detection target 44, an eddy current (Ie) flows through the detection target 44 according to the law of electromagnetic induction to generate a magnetic flux (Φe). Since the amount of magnetic flux changes according to the displacement between the detection target 44 and the coil 42, the eddy current (Ie) flowing through the detection target 44 changes, and as a result, the resistance (R) and inductance (L) of the coil 42. And (Q value) change. By comparing this change with the reference in the comparison circuit 45, a binary ON or OFF signal is generated based on (Q value), and an output voltage (Vo) corresponding to the signal is output through the output circuit 46. Output. The displacement at which the level of the output voltage (Vo) is switched ON or OFF is the detection distance (L) (see Patent Documents 1 and 2).

上記の円筒状ポットコア４１に内蔵のコイル４２が発振要素の場合も検出対象４４に流れる渦電流が変わり、その結果としてコイル４２の抵抗（Ｒ）とインダクタンス（Ｌ）および（Ｑ値）が変化し、同様に出力回路４６の出力電圧（Ｖｏ）がＯＮまたはＯＦＦに切り替わる変位が検出距離Ｌである。
米国特許６８２２４４０ 米国特許７２６２５９５ Even when the coil 42 built in the cylindrical pot core 41 is an oscillating element, the eddy current flowing through the detection target 44 changes, and as a result, the resistance (R), inductance (L), and (Q value) of the coil 42 change. Similarly, the displacement at which the output voltage (Vo) of the output circuit 46 is switched ON or OFF is the detection distance L.
US Pat. No. 6,822,440 US Pat. No. 7,262,595

しかしながら、図５の誘導型近接センサでは、図６に示すように円筒状ポットコア４１の外径（Ｄ）に対する検出距離（Ｌ）の比（Ｌ／Ｄ）が一定の値（Ｋ１）を有しており、長い検出距離（Ｌ）のためには外径（Ｄ）の大きな近接センサを使用する必要があった。そのため、従来の誘導型近接センサでは、検出距離（Ｌ）を長くしようとするとそのコア外径サイズが大形化してくるものとなっていた。そのため、大きな上記比（Ｌ／Ｄ）、すなわち、コア外径サイズに対して従来よりも検出距離（Ｌ）が長い誘導型近接センサが望まれていた。   However, in the inductive proximity sensor of FIG. 5, the ratio (L / D) of the detection distance (L) to the outer diameter (D) of the cylindrical pot core 41 has a constant value (K1) as shown in FIG. Therefore, it is necessary to use a proximity sensor having a large outer diameter (D) for a long detection distance (L). Therefore, in the conventional inductive proximity sensor, when the detection distance (L) is increased, the outer diameter of the core is increased. Therefore, an inductive proximity sensor having a large detection ratio (L) as compared with the conventional technique has been desired with respect to the large ratio (L / D), that is, the core outer diameter size.

また、上記用途において誘導型近接センサにおける検出動作の精密化、高速化、高信頼性への要求は増大しているが、この要求を実現するうえでは、近接センサの大形化や２重化が必要で、機械／装置の小形化／高精度化への対応が困難になっており、誘導型近接センサの小型化、高感度化、高信頼性化が望まれていた。   In addition, in the above applications, there are increasing demands for precise, high-speed, and high-reliability detection operations in inductive proximity sensors. To realize this requirement, the proximity sensor is increased in size and duplex. Therefore, it is difficult to cope with downsizing / accuracy of machines / devices, and downsizing, high sensitivity, and high reliability of inductive proximity sensors have been desired.

本発明は上記の事情に鑑みて案出されたものであり、上記比（Ｌ／Ｄ）が大きい誘導型近接センサを提供することを目的としている。   The present invention has been devised in view of the above circumstances, and an object thereof is to provide an inductive proximity sensor having a large ratio (L / D).

上記課題を解決するために、本発明は以下の手段を提供する。   In order to solve the above problems, the present invention provides the following means.

請求項１にかかる本発明は、Ｕ形のコアと、前記コアに巻かれた、発振要素としてのコイルと、前記コイルを含む発振回路と、前記コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、前記比較回路の出力を増幅する出力回路と、を有する誘導型近接センサである。   The present invention according to claim 1 includes a U-shaped core, a coil as an oscillation element wound around the core, an oscillation circuit including the coil, a binary ON or An inductive proximity sensor having a comparison circuit for generating an OFF signal and an output circuit for amplifying the output of the comparison circuit.

請求項２にかかる本発明は、Ｕ形のコアと、前記コアに巻かれて励振電流が流されるコイルと、前記コイルに励振電流を供給する励磁電流供給回路と、前記コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、前記比較回路の出力を増幅する出力回路と、を有する誘導型近接センサである。   The present invention according to claim 2 is based on a U-shaped core, a coil that is wound around the core and in which an excitation current flows, an excitation current supply circuit that supplies the coil with an excitation current, and a Q value of the coil An inductive proximity sensor having a comparison circuit that generates a binary ON or OFF signal and an output circuit that amplifies the output of the comparison circuit.

請求項３にかかる本発明は、請求項１または２に記載の誘導型近接センサにおいて、上記Ｕ形コアは、複数に分割できるコアからなる誘導型近接センサである。   According to a third aspect of the present invention, in the inductive proximity sensor according to the first or second aspect, the U-shaped core is an inductive proximity sensor comprising a core that can be divided into a plurality of parts.

請求項４にかかる本発明は、Ｕ形のコアと、前記コアに巻かれた、磁界検出コイルとしての第１コイルと、前記コアに巻かれて検出対象を励磁する励振電流が流される第２コイルと、前記第１コイルを含む検出／補正発振回路と、前記第２コイルに励振電流を供給する励磁電流供給回路と、前記第１、第２コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、前記比較回路の出力を増幅する出力回路と、を有する誘導型近接センサである。   According to a fourth aspect of the present invention, there is provided a U-shaped core, a first coil wound around the core as a magnetic field detection coil, and a second current passed through the core to excite a detection target. A coil, a detection / correction oscillation circuit including the first coil, an excitation current supply circuit for supplying an excitation current to the second coil, and a binary ON or OFF based on the Q values of the first and second coils An inductive proximity sensor having a comparison circuit for generating an OFF signal and an output circuit for amplifying the output of the comparison circuit.

以上の本発明では、Ｕ形コアの磁極間距離が長いために、近接効果に起因するコイルの抵抗増加を抑制して、より多くの磁束が、より遠くまで検出対象に作用させることができるようになる結果、検出距離（Ｌ）を拡大させることができる。   In the present invention described above, since the distance between the magnetic poles of the U-shaped core is long, an increase in the resistance of the coil due to the proximity effect can be suppressed, so that more magnetic flux can act on the detection target farther. As a result, the detection distance (L) can be increased.

上記Ｕ形コアに装着されたコイルが発振要素の場合も同様である。   The same applies when the coil mounted on the U-shaped core is an oscillation element.

上記Ｕ形コアが、複数に分割できるコアからなっている場合、複数に分割されたコアにコイルを装着した後にＵ形状にコアを形成するために、組み立てが容易で、かつ安価な誘導型近接センサを提供できる。   When the U-shaped core is composed of a core that can be divided into a plurality of cores, an inductive proximity that is easy to assemble and inexpensive to form a U-shaped core after the coil is mounted on the core divided into a plurality of cores. A sensor can be provided.

本発明では、Ｕ形コアに巻かれた独立した複数個のコイルをもち、センサヘッドの２重化による信頼性向上、または独立した励磁コイルおよび検出コイルによる高感度検出の誘導型近接センサを提供できる。   The present invention provides an inductive proximity sensor that has a plurality of independent coils wound around a U-shaped core and improves reliability by duplicating the sensor head, or high sensitivity detection using independent excitation coils and detection coils. it can.

本発明によれば、小形で長い検出距離を可能にし、高感度／高信頼性、かつ安価な誘導型近接センサを提供できる。   According to the present invention, a small and long detection distance can be achieved, and a highly sensitive / reliable and inexpensive inductive proximity sensor can be provided.

以下、添付した図面を参照して本発明の実施の形態にかかる誘導型近接センサを詳細に説明すると、図１（ａ）（ｂ）（ｃ）は、本発明の実施の形態にかかる誘導型近接センサの構造を示す。図１（ａ）（ｂ）（ｃ）では誘導型近接センサの電子回路である発振回路４３、比較回路４５、および出力回路４６の図示は略しているが、図５のそれと同様に、実施の形態の誘導型近接センサは上記電子回路を備えている。図１（ａ）は検出対象を含め誘導型近接センサの、側面から見た断面構成、図１（ｂ）は図１（ａ）の誘導型近接センサを検出対象とは反対方向から見た構成、図１（ｃ）はＵ形コアにおいてその分割状態から組立状態までを示す。実施の形態の誘導型近接センサは、Ｕ形コア１を備える。このＵ形コア１は、互いに平行に対向し脚端面が検出対象３の方向に向け延びる同一脚長を有する一対のコア脚１ａ，１ｂと、これらコア脚１ａ，１ｂを、それらの上記平行対向を維持した状態にして、連結するヨーク部１ｃと、を一体化して構成されている。このヨーク部１ｃにはコイル２が装着されている。   Hereinafter, an inductive proximity sensor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 (a), (b), and (c) are inductive type according to an embodiment of the present invention. The structure of a proximity sensor is shown. In FIGS. 1A, 1B, and 1C, the oscillation circuit 43, the comparison circuit 45, and the output circuit 46, which are electronic circuits of the inductive proximity sensor, are not shown. However, as in FIG. An inductive proximity sensor of the form includes the electronic circuit. 1A is a cross-sectional configuration of the inductive proximity sensor including a detection target, as viewed from the side, and FIG. 1B is a configuration of the inductive proximity sensor of FIG. 1A viewed from the opposite direction to the detection target. FIG.1 (c) shows from the division | segmentation state to an assembly state in a U-shaped core. The inductive proximity sensor according to the embodiment includes a U-shaped core 1. This U-shaped core 1 has a pair of core legs 1a and 1b having the same leg length that face each other in parallel and whose leg end surfaces extend in the direction of the detection target 3, and these core legs 1a and 1b are arranged in parallel with each other. In a maintained state, the yoke part 1c to be coupled is integrated. A coil 2 is attached to the yoke portion 1c.

コイル２はヨーク部１ｃに直接巻回してもよいが、ボビンに取り付けた形態とか、耐熱樹脂モールドで一体化した形態の場合では、Ｕ形コア１を複数のコアで構成し分割可能とすることでＵ形コア１に装着可能としてもよい。例えば、Ｕ形コア１を図１（ｃ）のｃ１で示すように、例えばＬ形コア１１と、Ｉ形コア１２との組み合わせで構成する。Ｌ形コア１１は上記コア脚１ａとヨーク部１ｃを構成するコア部分１１ａ，１１ｂを備え、Ｉ形コア１２は上記コア脚１ｂを構成する。そして、図１（ｃ）のｃ２で示すように、Ｌ形コア１１のコア部分１１ｂにコイル２を装着した後、図１（ｃ）のｃ３で示すように、Ｌ形コア１１と、Ｉ形コア１２とを組み付けることで、Ｕ形コア１を製作することができる。コイル２はコア部分１１ｂに巻回して組み付けるのではなく、成型されていて中央の挿通穴にコア部分１１ｂを通すことでコア部分１１ｂに装着組み付けすることができるようになっている。   The coil 2 may be wound directly around the yoke portion 1c. However, in the case of a form attached to a bobbin or a form integrated with a heat-resistant resin mold, the U-shaped core 1 is constituted by a plurality of cores and can be divided. Can be attached to the U-shaped core 1. For example, the U-shaped core 1 is constituted by a combination of an L-shaped core 11 and an I-shaped core 12 as indicated by c1 in FIG. The L-shaped core 11 includes core portions 11a and 11b that constitute the core leg 1a and the yoke portion 1c, and the I-shaped core 12 constitutes the core leg 1b. And after attaching the coil 2 to the core part 11b of the L-shaped core 11, as shown by c2 of FIG.1 (c), as shown by c3 of FIG.1 (c), the L-shaped core 11 and I-shaped By assembling the core 12, the U-shaped core 1 can be manufactured. The coil 2 is not wound around the core portion 11b and assembled, but is molded and can be mounted and assembled to the core portion 11b by passing the core portion 11b through the central insertion hole.

また、Ｕ形コア１のコア脚１ａ，１ｂのコア端面と対面する位置に金属製の検出対象３が配置されている。周波数（ｆ）の励振電流がコイル２に流れると、図示するごとく３つの形態の磁束（Φａ），（Φｂ），（Φｃ）が発生する。これら磁束（Φａ），（Φｂ），（Φｃ）は、（１）コイル２内を貫通する磁束（Φａ）、（２）コア脚１ａから出て、検出対象３まで届かずにコア脚１ｂに戻ってくる磁束（Φｂ）、（３）コア脚１ａから出て、検出対象３まで届きその後にコア脚１ｂに戻る磁束（Φｃ）、に分類される。上記図５の円筒状ポットコア４１に内蔵したコイル４２が発振要素の場合も同様な構造（電子回路は省略）であり、同様な磁束分布をする。   Further, a metal detection target 3 is disposed at a position facing the core end surfaces of the core legs 1a and 1b of the U-shaped core 1. When an excitation current having a frequency (f) flows through the coil 2, three forms of magnetic flux (Φa), (Φb), and (Φc) are generated as shown in the figure. These magnetic fluxes (Φa), (Φb), and (Φc) are (1) magnetic flux (Φa) penetrating through the coil 2 and (2) exiting from the core leg 1a and not reaching the detection target 3 to the core leg 1b. Returning magnetic flux (Φb), (3) Magnetic flux (Φc) that comes out of the core leg 1a, reaches the detection target 3, and then returns to the core leg 1b. When the coil 42 built in the cylindrical pot core 41 of FIG. 5 is an oscillating element, it has the same structure (the electronic circuit is omitted) and has the same magnetic flux distribution.

図２は、コイル２のＱ値−変位ｘ（ｍ）、およびｄＱ／ｄｘ−変位ｘ（ｍ）の特性を示す。コイル２のＱ値は変位ｘ（ｍ）に対して単調増加しており、また、ｄＱ／ｄｘはある変位ｘ（ｍ）で最大となり、その後は、単調減少する。ｄＱ／ｄｘ＝…となる変位ｘ（ｍ）が検出距離（Ｌ）であり、このときのＱ値に基づいて比較回路においてＯＮとＯＦＦ信号を発生させている。コイルのＱ値は、検出対象３の変位ｘ（ｍ）に依存しており、数１で与えられる。   FIG. 2 shows characteristics of the Q value-displacement x (m) and dQ / dx-displacement x (m) of the coil 2. The Q value of the coil 2 monotonously increases with respect to the displacement x (m), and dQ / dx becomes maximum at a certain displacement x (m), and thereafter monotonously decreases. The displacement x (m) where dQ / dx =... is the detection distance (L), and ON and OFF signals are generated in the comparison circuit based on the Q value at this time. The Q value of the coil depends on the displacement x (m) of the detection target 3 and is given by Equation 1.

Figure 2009264992
Figure 2009264992

ここに、ｆ：励振電流の周波数（Ｈｚ）、Ｌ：コイル２のインダクタンス（Ｈ）、Ｒ：コイル２の交流抵抗（Ω）、Ｒｄｃ：コイル２の直流抵抗（Ω）、Ｒｓ：コイル導線の表皮効果に起因する抵抗（Ω）、Ｒｐ：コイル２の近接効果に起因する抵抗（Ω）、Ｒｃ：コア１の鉄損に起因する抵抗（Ω）、Ｒｍ（ｘ）：検出対象３の鉄損に起因する抵抗（Ω）である。   Where f: frequency of excitation current (Hz), L: inductance of coil 2 (H), R: AC resistance of coil 2 (Ω), Rdc: DC resistance of coil 2 (Ω), Rs: coil conductor Resistance due to skin effect (Ω), Rp: Resistance due to proximity effect of coil 2 (Ω), Rc: Resistance due to iron loss of core 1 (Ω), Rm (x): Iron of detection object 3 Resistance (Ω) due to loss.

上記数１において、コイル１のインダクタンス（Ｌ）は変位ｘ（ｍ）によらず一定である。抵抗（Ｒｐ）は前述した項目（１）のコイル２内を貫通する磁束（Φａ）に起因しており、また、抵抗（Ｒｃ）はコア１内を磁束が通ることによって生じている。さらに、抵抗Ｒｍ（ｘ）は、前述した項目（３）のコア１から出て検出対象まで届きその後にコア２に戻る磁束（Φｃ）、に起因している。   In Equation 1, the inductance (L) of the coil 1 is constant regardless of the displacement x (m). The resistance (Rp) is caused by the magnetic flux (Φa) penetrating the coil 2 of the item (1) described above, and the resistance (Rc) is generated by the magnetic flux passing through the core 1. Further, the resistance Rm (x) is caused by the magnetic flux (Φc) that leaves the core 1 and reaches the detection target in the item (3) and returns to the core 2 after that.

誘導型近接センサではコイル２のＱ（ｘ）に基づいてＯＮとＯＦＦ動作を行っており、安定した動作を行うためには、数２に示したＱ（ｘ）の変位ｘ（ｍ）に対する微分ｄＱ（ｘ）／ｄｘが大きいことが必要である。   The inductive proximity sensor performs ON and OFF operations based on the Q (x) of the coil 2, and in order to perform a stable operation, the differential of Q (x) shown in Equation 2 with respect to the displacement x (m). It is necessary that dQ (x) / dx is large.

Figure 2009264992
Figure 2009264992

数２において、ｄＱ（ｘ）／ｄｘを大きく、すなわち検出距離Ｌを拡大するためには、周波数（ｆ）を高くする、インダクタンス（Ｌ）を大きくする必要がある。さらに、コイル２の直流抵抗（Ｒｄｃ）、表皮効果に起因する抵抗（Ｒｓ）、コイルの近接効果に起因する抵抗（Ｒｐ）およびコアの鉄損に起因する抵抗（Ｒｃ）を小さく、ｄＲｍ（ｘ）／ｄｘを大きくすれば良いことを示唆している。上記インダクタンス（Ｌ），抵抗（Ｒｄｃ），（Ｒｓ）は励振周波数（ｆ）とコイル導線の導体径およびコイル２の巻数を適切に選定することで最適化でき、また、低鉄損特性を有するコア２を採用することで抵抗（Ｒｃ）を低減できる。これらのことは、本発明および従来技術においても共通の事項であり、以下では、本発明の特長である抵抗（Ｒｐ）の低減とｄＲｍ（ｘ）／ｄｘ特性の向上に着目して説明する。   In Equation 2, in order to increase dQ (x) / dx, that is, to increase the detection distance L, it is necessary to increase the frequency (f) and increase the inductance (L). Furthermore, the DC resistance (Rdc) of the coil 2, the resistance (Rs) due to the skin effect, the resistance (Rp) due to the proximity effect of the coil and the resistance (Rc) due to the core loss of the core are reduced, and dRm (x ) / Dx should be increased. The inductance (L), resistance (Rdc), and (Rs) can be optimized by appropriately selecting the excitation frequency (f), the conductor diameter of the coil conductor, and the number of turns of the coil 2, and have low iron loss characteristics. By adopting the core 2, the resistance (Rc) can be reduced. These matters are common to the present invention and the prior art, and the following description will focus on reducing the resistance (Rp) and improving the dRm (x) / dx characteristics, which are features of the present invention.

図５に示した従来技術の誘導型近接センサの磁束も前述したように以下の３種類、すなわち （１）コイル４２内を貫通する磁束（Φａ）、（２）中央脚４１ａから出て検出対象４４まで届かずに外周脚４１ｂに戻ってくる磁束（Φｂ）、（３）中央脚４１ａから出て検出対象４４まで届きその後に外周脚４１ｂに戻る磁束（Φｃ）、に分類される。   As described above, the magnetic flux of the prior art inductive proximity sensor shown in FIG. 5 is also divided into the following three types: (1) magnetic flux penetrating the coil 42 (Φa), (2) coming out of the center leg 41a and to be detected Magnetic flux (Φb) that returns to the outer peripheral leg 41b without reaching 44, and (3) Magnetic flux (Φc) that exits from the central leg 41a to the detection target 44 and then returns to the outer peripheral leg 41b.

図１に示した本発明の誘導型近接センサは、図５に示した従来技術の誘導型近接センサと比較して以下の利点がある。本発明では、コア脚１ａ，１ｂ間の距離が従来技術より長いために、コイル２内を貫通する磁束が少なくなり、近接効果に起因する抵抗（Ｒｐ）が小さくなる。また、同様の理由によって、より多くの磁束が検出対象３に、より遠くまで作用して、ｄＲｍ（ｘ）／ｄｘ特性が向上する。したがって、数２に示したｄＱ（ｘ）／ｄｘが従来技術よりも大きくなって検出距離Ｌが拡大する。   The inductive proximity sensor of the present invention shown in FIG. 1 has the following advantages over the prior art inductive proximity sensor shown in FIG. In the present invention, since the distance between the core legs 1a and 1b is longer than that in the prior art, the magnetic flux penetrating the coil 2 is reduced, and the resistance (Rp) due to the proximity effect is reduced. For the same reason, more magnetic flux acts on the detection target 3 farther, and the dRm (x) / dx characteristic is improved. Therefore, dQ (x) / dx shown in Equation 2 becomes larger than that in the prior art, and the detection distance L is increased.

図３は、本発明と従来技術の検出距離（Ｌ）−コア外径（Ｄ）特性を比較する図である。上述した理由によって、上記特性において本発明は従来技術よりも向上する。   FIG. 3 is a diagram comparing the detection distance (L) -core outer diameter (D) characteristics of the present invention and the prior art. For the reasons described above, the present invention improves the above characteristics over the prior art.

本発明において、Ｕ形のコア１はコア脚１ａとコア脚１ｂとに２分割された実施例を示したが、こうした２分割コアに限定されるものではない。   In the present invention, the U-shaped core 1 is divided into the core leg 1a and the core leg 1b. However, the present invention is not limited to such a two-divided core.

図４は、Ｕ形コア１に巻かれ独立した２個のコイル２１，２２をもつ構成例である。コイル２１は検出専用として、検出／補正回路４に接続され、コイル２２は検出対象３への励磁専用として、発振／励磁回路５に接続されている。検出／補正回路４と発振／励磁回路５それぞれの後段側に、制御・演算回路６が接続され、この制御・演算回路６には表示部７、出力回路８が接続されている。上記構成例においては、励磁電流に重畳された検出対象３の渦電流による電流変化検出に比べて信号対ノイズ比のよい高感度な検出ができる。また、制御・演算回路６内のＣＰＵにより、上記発振、検出、補正、表示、外部出力をきめ細かく制御することができる。   FIG. 4 is a configuration example having two independent coils 21 and 22 wound around the U-shaped core 1. The coil 21 is connected to the detection / correction circuit 4 exclusively for detection, and the coil 22 is connected to the oscillation / excitation circuit 5 exclusively for excitation of the detection target 3. A control / arithmetic circuit 6 is connected to the downstream side of each of the detection / correction circuit 4 and the oscillation / excitation circuit 5, and a display unit 7 and an output circuit 8 are connected to the control / arithmetic circuit 6. In the above configuration example, high-sensitivity detection with a good signal-to-noise ratio can be performed as compared with the current change detection by the eddy current of the detection target 3 superimposed on the excitation current. Further, the oscillation, detection, correction, display, and external output can be finely controlled by the CPU in the control / arithmetic circuit 6.

本発明における誘導型近接センサの構造を示す図である。It is a figure which shows the structure of the inductive proximity sensor in this invention. コイルのＱ（ｘ）値およびｄＱ（ｘ）／ｄｘ−変位特性を示す図である。It is a figure which shows the Q (x) value and dQ (x) / dx-displacement characteristic of a coil. 本発明と従来技術の検出距離−コアの外径特性の比較を示す図である。It is a figure which shows the comparison of the outer diameter characteristic of the detection distance-core of this invention and a prior art. 独立した２個のコイルを有する高感度渦電流近接センサ構成例を示す図である。It is a figure which shows the example of a highly sensitive eddy current proximity sensor structure which has two independent coils. 従来技術の誘導型近接センサの構造を示す図である。It is a figure which shows the structure of the induction type proximity sensor of a prior art. 従来技術の検出距離−コアの外径特性を示す図である。It is a figure which shows the outer diameter characteristic of the detection distance-core of a prior art.

符号の説明Explanation of symbols

１ Ｕ形コア
２ コイル
３ 検出対象 1 U-shaped core 2 Coil 3 Detection target

Claims (4)

Ｕ形のコアと、
前記コアに巻かれた、発振要素としてのコイルと、
前記コイルを含む発振回路と、
前記コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、
前記比較回路の出力を増幅する出力回路と、
を有する誘導型近接センサ。 A U-shaped core,
A coil as an oscillation element wound around the core;
An oscillation circuit including the coil;
A comparison circuit for generating a binary ON or OFF signal based on the Q value of the coil;
An output circuit for amplifying the output of the comparison circuit;
An inductive proximity sensor. Ｕ形のコアと、
前記コアに巻かれて励振電流が流されるコイルと、
前記コイルに励振電流を供給する励磁電流供給回路と、
前記コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、
前記比較回路の出力を増幅する出力回路と、
を有する誘導型近接センサ。 A U-shaped core,
A coil wound around the core and having an excitation current flow;
An excitation current supply circuit for supplying an excitation current to the coil;
A comparison circuit for generating a binary ON or OFF signal based on the Q value of the coil;
An output circuit for amplifying the output of the comparison circuit;
An inductive proximity sensor. 上記Ｕ形コアは、複数に分割できるコアからなる請求項１または２に記載の誘導型近接センサ。   The inductive proximity sensor according to claim 1, wherein the U-shaped core includes a core that can be divided into a plurality of parts. Ｕ形のコアと、
前記コアに巻かれた、磁界検出コイルとしての第１コイルと、
前記コアに巻かれて検出対象を励磁する励振電流が流される第２コイルと、
前記第１コイルを含む検出／補正発振回路と、
前記第２コイルに励振電流を供給する励磁電流供給回路と、
前記第１、第２コイルのＱ値に基づいて二値のＯＮまたはＯＦＦ信号を発生させる比較回路と、
前記比較回路の出力を増幅する出力回路と、
を有する誘導型近接センサ。 A U-shaped core,
A first coil wound around the core as a magnetic field detection coil;
A second coil that is wound around the core and is supplied with an excitation current that excites the detection target;
A detection / correction oscillation circuit including the first coil;
An excitation current supply circuit for supplying an excitation current to the second coil;
A comparison circuit for generating a binary ON or OFF signal based on the Q values of the first and second coils;
An output circuit for amplifying the output of the comparison circuit;
An inductive proximity sensor.
JP2008116617A 2008-04-28 2008-04-28 Induction type proximity sensor Pending JP2009264992A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012191022A (en) * 2011-03-11 2012-10-04 Shinshu Univ Method for calculating ac resistance of coil
WO2014129703A1 (en) * 2013-02-21 2014-08-28 Truwin Co.,Ltd. Inductive proximity sensor

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JPS62186614A (en) * 1986-02-13 1987-08-15 Yamatake Honeywell Co Ltd Proximity switch
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JPH0614982U (en) * 1992-07-23 1994-02-25 株式会社コパル Proximity sensor
JPH0729466A (en) * 1993-07-13 1995-01-31 Omron Corp Proximity switch
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Publication number Priority date Publication date Assignee Title
JPS61267216A (en) * 1985-05-20 1986-11-26 オムロン株式会社 Proximity switch
JPS62186614A (en) * 1986-02-13 1987-08-15 Yamatake Honeywell Co Ltd Proximity switch
JPS62178432U (en) * 1986-05-02 1987-11-12
JPH0614982U (en) * 1992-07-23 1994-02-25 株式会社コパル Proximity sensor
JPH0729466A (en) * 1993-07-13 1995-01-31 Omron Corp Proximity switch
JP2001274028A (en) * 2000-01-21 2001-10-05 Tamura Seisakusho Co Ltd Reactor
JP2004047849A (en) * 2002-07-15 2004-02-12 Jfe Steel Kk Planar magnetic element
JP2007501509A (en) * 2003-07-31 2007-01-25 アプライド　マテリアルズ　インコーポレイテッド Eddy current system for in-situ profile measurement
JP2005315732A (en) * 2004-04-28 2005-11-10 Jfe Steel Kk Instrument for measuring displacement of ferromagnetic body

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012191022A (en) * 2011-03-11 2012-10-04 Shinshu Univ Method for calculating ac resistance of coil
WO2014129703A1 (en) * 2013-02-21 2014-08-28 Truwin Co.,Ltd. Inductive proximity sensor

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