JP4305271B2

JP4305271B2 - Magnetostrictive torque sensor

Info

Publication number: JP4305271B2
Application number: JP2004138806A
Authority: JP
Inventors: 松欧陽
Original assignee: Hitachi Cable Ltd
Current assignee: Hitachi Cable Ltd
Priority date: 2004-05-07
Filing date: 2004-05-07
Publication date: 2009-07-29
Anticipated expiration: 2024-05-07
Also published as: JP2005321272A

Description

本発明は、非接触磁歪式トルクセンサ、特に、磁歪特性を有する回転軸に加わるトルクを、透磁率変化による検出コイルのインダクタンス変化から非接触的に検出する非接触磁歪式トルクセンサに関する。 The present invention relates to a non-contact magnetostrictive torque sensor, and more particularly to a non-contact magnetostrictive torque sensor that detects, in a non-contact manner, a torque applied to a rotating shaft having magnetostrictive characteristics from a change in inductance of a detection coil caused by a change in permeability.

自動車のパワーステアリング機構、エンジン制御機構、動力伝達機構などでは回転軸であるハンドル軸、その他の受動軸などに加わるトルクを検出する必要性が高い。 In a power steering mechanism, an engine control mechanism, a power transmission mechanism, and the like of an automobile, there is a high need to detect torque applied to a handle shaft that is a rotating shaft and other passive shafts.

一般に、磁歪特性を有する材料は、力を加えると比透磁率が変化し、圧縮力方向では比透磁率が減少し、張力方向では比透磁率が増加する。この原理を利用した磁歪式トルク検出装置が、例えば特許文献１に記載されている。 In general, when a force is applied to a material having magnetostrictive characteristics, the relative permeability changes, the relative permeability decreases in the compressive force direction, and the relative permeability increases in the tension direction. A magnetostrictive torque detection device using this principle is described in Patent Document 1, for example.

図１１（ａ）に特許文献１に記載されている磁歪式トルク検出装置の略図を示す。図１１（ａ）の磁歪式トルク検出装置は、受動軸である回転軸１１の外周に、回転軸１１に対して±４５°に複数の磁歪膜１３、１３を固着し、その外周に±４５°磁歪膜１３、１３に対応してリング形検出コイル１２、１２を配設したものである。回転軸１１に外部からトルクが印加されると、磁歪膜１３、１３の一方には張力が、他方には圧縮力が発生して歪が生じ、磁歪膜１３、１３の透磁率が変化する。この磁歪膜１３、１３の透磁率変化によるリング形検出コイル１２、１２のインダクタンス変化を検出して出力する。 FIG. 11A shows a schematic diagram of a magnetostrictive torque detection device described in Patent Document 1. FIG. In the magnetostrictive torque detection apparatus of FIG. 11A, a plurality of magnetostrictive films 13 and 13 are fixed to the outer periphery of the rotary shaft 11 that is a passive shaft at ± 45 ° with respect to the rotary shaft 11, and ± 45 to the outer periphery thereof. The ring-shaped detection coils 12 and 12 are disposed corresponding to the magnetostrictive films 13 and 13, respectively. When torque is applied to the rotating shaft 11 from the outside, a tension is generated in one of the magnetostrictive films 13 and 13 and a compressive force is generated in the other, resulting in distortion, and the magnetic permeability of the magnetostrictive films 13 and 13 changes. Changes in the inductance of the ring-shaped detection coils 12 and 12 due to changes in the magnetic permeability of the magnetostrictive films 13 and 13 are detected and output.

上述した磁歪式トルク検出装置の他に、図１１（ｂ）に示すものがある。図１１（ｂ）の磁歪式トルク検出装置は、磁歪回転軸１１に対向配置したＵ字形磁心１４上に巻回した検出コイル１２、１２を使用することにより、磁歪回転軸１１の透磁率変化を検出して出力するものである。
特開平１−９４２３０号公報 In addition to the magnetostrictive torque detector described above, there is one shown in FIG. The magnetostrictive torque detecting device of FIG. 11B uses the detection coils 12 and 12 wound on the U-shaped magnetic core 14 disposed opposite to the magnetostrictive rotating shaft 11 to change the permeability of the magnetostrictive rotating shaft 11. It is detected and output.
JP-A-1-94230

しかし、図１１（ａ）の磁歪式トルク検出装置によれば、回転軸１１に±４５°の磁歪膜１３、１３を固着するため、回転軸１１を加工する必要があるという問題がある。 However, according to the magnetostrictive torque detecting device of FIG. 11A, there is a problem that the rotating shaft 11 needs to be processed because the ± 45 ° magnetostrictive films 13 and 13 are fixed to the rotating shaft 11.

また、図１１（ｂ）の磁歪式トルク検出装置によれば、回転軸１１を加工する必要がなく、回転軸１１に装着容易であるが、検出コイル１２が巻かれたＵ字形磁心１４は回転軸１１に対してリング形磁心のような回転対称でなく、回転軸１１がＵ字形磁心１４に対面していない部分があるため、出力信号の感度が低く、出力信号のゼロ点が回転軸１１の回転に伴って、大きく変動してしまうという問題がある。 Further, according to the magnetostrictive torque detecting device of FIG. 11B, it is not necessary to process the rotating shaft 11 and it can be easily mounted on the rotating shaft 11, but the U-shaped magnetic core 14 around which the detection coil 12 is wound is rotated. Since there is a portion that is not rotationally symmetric like the ring-shaped magnetic core with respect to the shaft 11 and the rotating shaft 11 does not face the U-shaped magnetic core 14, the sensitivity of the output signal is low, and the zero point of the output signal is the rotating shaft 11. There is a problem that it fluctuates greatly with the rotation of.

従って、本発明の目的は、回転軸に±４５°の磁歪膜を固着するなどの加工を施すことなく、出力信号の感度を向上し、回転軸の回転に伴う出力信号のゼロ点変動を小さくすることによって、磁歪回転軸に加わるトルクを精度よく検出する非接触磁歪式トルクセンサを提供することにある。 Accordingly, the object of the present invention is to improve the sensitivity of the output signal without applying a process such as fixing a ± 45 ° magnetostrictive film to the rotating shaft, and to reduce the zero point fluctuation of the output signal accompanying the rotation of the rotating shaft. Accordingly, it is an object of the present invention to provide a non-contact magnetostrictive torque sensor that accurately detects torque applied to the magnetostrictive rotating shaft.

また、本発明の更なる目的は、回転軸の圧縮方向及び張力方向の磁束変化を検出する非接触磁歪式トルクセンサを提供することにある。 A further object of the present invention is to provide a non-contact magnetostrictive torque sensor that detects changes in magnetic flux in the compression direction and tension direction of the rotating shaft.

更に、本発明の他の目的は、コイルの検出感度が高い非接触磁歪式トルクセンサを提供することにある。 Another object of the present invention is to provide a non-contact magnetostrictive torque sensor with high coil detection sensitivity.

また、本発明の他の目的は、回転軸に装着容易である非接触磁歪式トルクセンサを提供することにある。 Another object of the present invention is to provide a non-contact magnetostrictive torque sensor that can be easily mounted on a rotating shaft.

更にまた、本発明の他の目的は、コイルの巻き方、検出回路の組み立て及び製造が容易な非接触磁歪式トルクセンサを提供することにある。 It is still another object of the present invention to provide a non-contact magnetostrictive torque sensor that is easy to wind a coil and assemble and manufacture a detection circuit.

本発明によると、中心軸の周りに回転する磁歪特性を有する回転軸と、前記回転軸の外周と所定の間隔を有しながら前記回転軸と同軸に配置された、前記回転軸の歪を検出するコイルを巻回した磁性リングを備えた磁歪式トルクセンサにおいて、
前記磁性リングは、前記中心軸に対して４５°傾いてその円周方向に交互に配置された強磁性部と非磁性部とから形成され、
前記コイルは、前記強磁性部と前記非磁性部の傾斜方向と直交する方向に巻回することを特徴とする磁歪式トルクセンサを提供する。 According to the present invention, a rotating shaft having a magnetostrictive characteristic that rotates around a central axis, and a distortion of the rotating shaft that is arranged coaxially with the rotating shaft while having a predetermined distance from an outer periphery of the rotating shaft are detected. In a magnetostrictive torque sensor having a magnetic ring around which a coil is wound,
The magnetic ring is formed of a ferromagnetic portion and a non-magnetic portion that are alternately arranged in a circumferential direction inclined by 45 ° with respect to the central axis,
The coil provides a magnetostrictive torque sensor, wherein the coil is wound in a direction orthogonal to the inclination direction of the ferromagnetic part and the nonmagnetic part.

前記磁性リングは、前記回転軸の張力方向の磁束変化を検出するために、前記回転軸の張力方向に傾斜してその円周方向に交互に配置された張力検出用強磁性部と張力検出用非磁性部とから形成された第１の磁性リングと、前記回転軸の圧縮方向の磁束変化を検出するために、前記回転軸の圧縮方向に傾斜してその円周方向に交互に配置された圧縮検出用強磁性部と圧縮検出用非磁性部とから形成された第２の磁性リングとを含み、
前記コイルは、前記第１の磁性リングに圧縮方向に傾斜して巻回された第１のコイルと、前記第２の磁性リングに張力方向に傾斜して巻回された第２のコイルとを含むことを特徴とする。 In order to detect a change in magnetic flux in the tension direction of the rotating shaft, the magnetic ring is inclined in the tension direction of the rotating shaft and alternately arranged in the circumferential direction and tension detecting ferromagnetic portions. In order to detect a change in magnetic flux in the compression direction of the rotating shaft, the first magnetic ring formed from a non-magnetic portion is alternately arranged in the circumferential direction inclining in the compressing direction of the rotating shaft. A second magnetic ring formed from a compression detecting ferromagnetic portion and a compression detecting non-magnetic portion;
The coil includes a first coil wound around the first magnetic ring in a compression direction, and a second coil wound around the second magnetic ring in a tension direction. It is characterized by including.

前記磁性リングは、前記非磁性部の面積が前記強磁性部の面積よりも小さいことを特徴とする。 The magnetic ring is characterized in that an area of the nonmagnetic part is smaller than an area of the ferromagnetic part.

前記磁性リングは、前記非磁性部の位置で、前記非磁性部の傾斜方向に沿って、２分割された半円筒磁心を含むことを特徴とする。 The magnetic ring includes a semi-cylindrical magnetic core that is divided into two at the position of the nonmagnetic portion along the inclination direction of the nonmagnetic portion.

前記２分割された半円筒磁心にそれぞれコイルを独立して巻回することを特徴とする。 A coil is independently wound around each of the two half-cylindrical magnetic cores.

本発明の非接触磁歪式トルクセンサによると、回転軸に対して４５°傾いたコイルにより発生する磁束が、強磁性部と非磁性部の傾き方向に集中するため、出力信号の感度を高くすることができる。また、該コイルは磁性リングの周囲に巻かれており回転軸に対して回転対称であるため、出力信号は回転軸の回転角度に依存することがない。即ち、回転軸の回転に伴う出力信号のゼロ点変動を小さくすることができる。 According to the non-contact magnetostrictive torque sensor of the present invention, the magnetic flux generated by the coil inclined by 45 ° with respect to the rotation axis is concentrated in the inclination direction of the ferromagnetic part and the non-magnetic part, so that the sensitivity of the output signal is increased. be able to. Further, since the coil is wound around the magnetic ring and is rotationally symmetric with respect to the rotation axis, the output signal does not depend on the rotation angle of the rotation axis. That is, the zero point fluctuation of the output signal accompanying the rotation of the rotating shaft can be reduced.

また、本発明によると、回転軸の張力方向に傾斜してその円周方向に交互に配置された張力検出用強磁性部と張力検出用非磁性部とから形成された第１の磁性リングに圧縮方向に傾斜して巻回された第１のコイルと、回転軸の圧縮方向に傾斜してその円周方向に交互に配置された圧縮検出用強磁性部と圧縮検出用非磁性部とから形成された第２の磁性リングに張力方向に傾斜して巻回された第２のコイルとを含むため、回転軸の張力方向及び圧縮方向の磁束変化を検出することができる。 Further, according to the present invention, the first magnetic ring formed of the tension detecting ferromagnetic portion and the tension detecting nonmagnetic portion which are inclined in the tension direction of the rotating shaft and are alternately arranged in the circumferential direction thereof. A first coil wound in the compression direction, and a ferromagnetic part for compression detection and a non-magnetic part for compression detection which are inclined in the compression direction of the rotating shaft and alternately arranged in the circumferential direction. Since it includes the second coil that is wound around the formed second magnetic ring while being inclined in the tension direction, it is possible to detect a change in magnetic flux in the tension direction and the compression direction of the rotating shaft.

また、本発明によると、磁性リングは、前記非磁性部の面積が前記強磁性部の面積よりも小さいため、コイルの検出感度を高くすることができる。 According to the present invention, the magnetic ring can increase the detection sensitivity of the coil because the area of the nonmagnetic portion is smaller than the area of the ferromagnetic portion.

更に、本発明によると、トルクセンサは２つの半円筒磁心に分割されるため、容易に磁歪回転軸に装着することができる。 Furthermore, according to the present invention, since the torque sensor is divided into two semi-cylindrical magnetic cores, it can be easily attached to the magnetostrictive rotating shaft.

また、本発明によると、２分割された半円筒磁心にそれぞれコイルを独立して巻回するため、コイルの巻き方、検出回路の組み立て及び製造が容易である。 In addition, according to the present invention, since the coils are wound independently around the half-cylindrical magnetic core divided into two, it is easy to wind the coils and to assemble and manufacture the detection circuit.

以下、本発明の実施の形態について図面を参照しながら説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１は、本発明の磁歪式トルクセンサの第１実施例を示す。この磁歪式トルクセンサは、磁歪特性を有する回転軸１０と、回転軸１０の軸Ｏに対して＋４５°傾いたコイル２１（以下、単に「＋４５°コイル」と呼ぶ）が周囲に巻かれた磁性リング３１とから構成され、＋４５°コイル２１が周囲に巻かれた磁性リング３１を回転軸１０に通して同心状に配置した構造を有する。＋４５°コイル２１が巻かれた磁性リング３１は、回転軸１０の軸Ｏに対して−４５°傾いた非磁性部３１ａ及び強磁性部３１ｂ（以下、それぞれ単に「−４５°非磁性部」及び「−４５°強磁性部」と呼ぶ）を併せ持つ複合磁性材料からなっており、図１に示すように、磁性リング３１は−４５°非磁性部３１ａ及び−４５°強磁性部３１ｂを円周方向に交互に配置した構造を有する。ここで、−４５°非磁性部３１ａは比透磁率が低いものが望ましく、−４５°強磁性部３１ｂは比透磁率が高いものが望ましい。また、−４５°非磁性部３１ａと−４５°強磁性部３１ｂの個数は４から２Ｎ（Ｎ＝２，３，４，…）である。また、＋４５°コイル２１の検出感度を高くするため、−４５°非磁性部３１ａの面積は−４５°強磁性部３１ｂの面積より小さいことが好ましい。 FIG. 1 shows a first embodiment of a magnetostrictive torque sensor according to the present invention. The magnetostrictive torque sensor includes a rotating shaft 10 having magnetostrictive characteristics, and a coil 21 (hereinafter simply referred to as a “+ 45 ° coil”) tilted by + 45 ° with respect to the axis O of the rotating shaft 10. The magnetic ring 31 is composed of a ring 31 and has a structure in which a magnetic ring 31 around which a + 45 ° coil 21 is wound is concentrically arranged through the rotary shaft 10. The magnetic ring 31 around which the + 45 ° coil 21 is wound includes a nonmagnetic portion 31a and a ferromagnetic portion 31b (hereinafter simply referred to as “−45 ° nonmagnetic portion”) and an inclined portion of −45 ° with respect to the axis O of the rotating shaft 10, respectively. As shown in FIG. 1, the magnetic ring 31 has a circumference of a −45 ° nonmagnetic portion 31a and a −45 ° ferromagnetic portion 31b. It has a structure that is alternately arranged in the direction. Here, the −45 ° nonmagnetic portion 31a desirably has a low relative permeability, and the −45 ° ferromagnetic portion 31b desirably has a high relative permeability. The number of the −45 ° nonmagnetic portion 31a and the −45 ° ferromagnetic portion 31b is 4 to 2N (N = 2, 3, 4,...). In order to increase the detection sensitivity of the + 45 ° coil 21, the area of the −45 ° nonmagnetic portion 31a is preferably smaller than the area of the −45 ° ferromagnetic portion 31b.

次に、本発明の磁歪式トルクセンサの動作原理について説明する。図２に示すように、軸方向Ｘから見て、図面で左側を反時計廻り方向に、図面で右側を時計廻り方向に力が働くように、回転軸１０にトルクＴが印加される。以下、この方向のトルクＴを正方向とする。このとき、回転軸１０の前側（紙面の表）から見て、回転軸１０の＋４５°方向には圧縮力が、−４５°方向には張力が加わることになる。この主応力σはトルクＴに比例し、回転軸１０の直径をＤとすると、次式で与えられる。
σ＝１６T/(πD^３) （１）
このとき、回転軸１０が磁歪効果を持っていれば、主応力σにより、軸磁気異方性Kuが誘起される。
Ku＝２・(３/２)λｓσ＝４８λｓT/(πD^３) （２）
ここで、λｓは回転軸１０の飽和磁歪定数である。この軸磁気異方性Kuによって、＋σ方向は磁化容易方向、−σ方向は磁化困難方向となり、静磁エネルギーの関係から、磁化容易方向＋σ方向の比透磁率は増加し、逆に磁化困難方向−σ方向の比透磁率は減少する。従って、磁化困難方向−σ方向（圧縮力方向）に傾くコイルに電流を流すと、コイルにより形成する磁束は磁化容易方向＋σ方向（張力方向）に傾いて張力方向の比透磁率が高くなるので、張力方向の磁束を減少させる方向に感応電流が流れ、感応電流によって感応電圧が誘起されるため、このコイルのインダクタンスは大きくなる。逆に、磁化容易方向＋σ方向（張力方向）に傾くコイルに電流を流すと、コイルにより形成する磁束は、磁化困難方向−σ方向（圧縮力方向）に傾いて圧縮力方向の比透磁率が小さくなるので、圧縮力方向の磁束を増加させる方向に感応電流が流れ、感応電流によって感応電圧が誘起されるため、このコイルのインダクタンスは小さくなる。 Next, the operation principle of the magnetostrictive torque sensor of the present invention will be described. As shown in FIG. 2, when viewed from the axial direction X, a torque T is applied to the rotary shaft 10 so that the left side is counterclockwise in the drawing and the right side is clockwise in the drawing. Hereinafter, the torque T in this direction is defined as the positive direction. At this time, when viewed from the front side of the rotating shaft 10 (the front surface of the drawing), a compressive force is applied to the rotating shaft 10 in the + 45 ° direction and a tension is applied to the −45 ° direction. The principal stress σ is proportional to the torque T, and is given by the following equation, where D is the diameter of the rotating shaft 10.
σ = 16T / (πD ³ ) (1)
At this time, if the rotating shaft 10 has a magnetostrictive effect, axial magnetic anisotropy Ku is induced by the main stress σ.
Ku = 2 · (3/2) λsσ = 48λsT / (πD ³ ) (2)
Here, λs is a saturation magnetostriction constant of the rotating shaft 10. Due to this axial magnetic anisotropy Ku, the + σ direction becomes the easy magnetization direction, the −σ direction becomes the magnetization difficult direction, and the relative permeability in the magnetization easy direction + σ direction increases due to the magnetostatic energy, and conversely the magnetization difficult direction. The relative permeability in the −σ direction decreases. Therefore, when a current is passed through a coil inclined in the hard magnetization direction-σ direction (compressive force direction), the magnetic flux formed by the coil is inclined in the easy magnetization direction + σ direction (tensile direction) and the relative permeability in the tension direction increases. Since the sensitive current flows in the direction of decreasing the magnetic flux in the tension direction and the sensitive voltage is induced by the sensitive current, the inductance of this coil increases. Conversely, when a current is passed through a coil inclined in the easy magnetization direction + σ direction (tensile direction), the magnetic flux formed by the coil is inclined in the difficult magnetization direction−σ direction (compressive force direction) and the relative permeability in the compressive force direction is increased. Since the sensitivity current flows in the direction of increasing the magnetic flux in the compressive force direction and the sensitivity voltage is induced by the sensitivity current, the inductance of the coil is reduced.

図１及び２に示すように、磁性リング３１は、−４５°非磁性部３１ａ及び−４５°強磁性部３１ｂを併せ持つ複合磁性材料からなっており、−４５°非磁性部３１ａ及び−４５°強磁性部３１ｂを円周方向に交互に配置した構造を有する。＋４５°コイル２１は、磁性リング３１の周囲に、回転軸１０の軸Ｏに対して＋４５°傾いて、−４５°非磁性部３１ａ及び−４５°強磁性部３１ｂに直交して巻かれている。従って、＋４５°コイル２１に電流Iを流したとき＋４５°コイル２１により発生する磁束Φは磁性リング３１の−４５°非磁性部３１ａ（非磁性部３１ａは−４５°方向に弱く磁化される）及び−４５°強磁性部３１ｂを通るため、図２に示すように磁束Φは強制的に回転軸１０の軸Ｏに対して−４５°傾いて回転軸１０を通る。よって、回転軸１０を通る磁束Φは磁化容易方向＋σ方向（張力方向）に集中して張力方向の比透磁率が大きくなるため、＋４５°コイル２１のインダクタンスは大きくなる。 As shown in FIGS. 1 and 2, the magnetic ring 31 is made of a composite magnetic material having both a −45 ° nonmagnetic portion 31a and a −45 ° ferromagnetic portion 31b, and the −45 ° nonmagnetic portion 31a and −45 °. The ferromagnetic portions 31b are alternately arranged in the circumferential direction. The + 45 ° coil 21 is wound around the magnetic ring 31 at an angle of + 45 ° with respect to the axis O of the rotating shaft 10 and orthogonal to the −45 ° nonmagnetic portion 31a and the −45 ° ferromagnetic portion 31b. . Accordingly, the magnetic flux Φ generated by the + 45 ° coil 21 when the current I flows through the + 45 ° coil 21 is −45 ° nonmagnetic portion 31a of the magnetic ring 31 (the nonmagnetic portion 31a is weakly magnetized in the −45 ° direction). Further, since it passes through the −45 ° ferromagnetic portion 31b, the magnetic flux Φ is forced to pass through the rotating shaft 10 with an inclination of −45 ° with respect to the axis O of the rotating shaft 10 as shown in FIG. Therefore, the magnetic flux Φ passing through the rotating shaft 10 is concentrated in the easy magnetization direction + σ direction (tensile direction) and the relative permeability in the tension direction is increased, so that the inductance of the + 45 ° coil 21 is increased.

図３は、上述した＋４５°コイル２１の電気特性から磁歪回転軸１０に印加されるトルクを検出するための検出回路である。＋４５°コイル２１と、３つの抵抗器Ｒ_１、Ｒ_２、Ｒ_３（Ｒ_１＝Ｒ_２＝Ｒ_３＝１０Ω）を用いて、図３に示すようなブリッジ回路を構成する。そして、直列接続された＋４５°検出コイル２１と抵抗器Ｒ_３、直列接続抵抗器Ｒ_１とＲ_２との両端に回路を駆動する発振器７０を接続し、＋４５°検出コイル２１と抵抗器Ｒ_３の間、及び直列接続抵抗器Ｒ_１とＲ_２の間に、トルク印加時にブリッジ回路から発生する差動信号を検出・増幅して出力するロックイン増幅器８０を接続する。 FIG. 3 is a detection circuit for detecting the torque applied to the magnetostrictive rotating shaft 10 from the electrical characteristics of the + 45 ° coil 21 described above. A bridge circuit as shown in FIG. 3 is configured by using the + 45 ° coil 21 and the three resistors R ₁ , R ₂ , and R ₃ (R ₁ = R ₂ = R ₃ = 10Ω). Then, an oscillator 70 for driving a circuit is connected to both ends of the + 45 ° detection coil 21 and the resistor R ₃ connected in series and the series connected resistors R ₁ and R _2, and the + 45 ° detection coil 21 and the resistor R ₃ are connected. And between the series-connected resistors R ₁ and R ₂ , a lock-in amplifier 80 that detects and amplifies and outputs a differential signal generated from the bridge circuit when torque is applied is connected.

次に、図３の検出回路の動作について説明する。発振器７０から発生する高周波数電流Ｉが抵抗器Ｒ_１と＋４５°検出コイル２１に流入し、抵抗器Ｒ_２と抵抗器Ｒ_３から流出する。トルクが印加されていないとき、検出回路が平衡状態になるようにゼロ点調整を行う。図２に示すように、正トルクＴが印加されるとき、＋４５°検出コイル２１のインダクタンスＬがΔＬ増加し、ロックイン増幅器８０からの出力Ｖは正方向に増加する。それに対して、負トルクが印加されるとき、＋４５°検出コイル２１のインダクタンスＬがΔＬ減少し、ロックイン増幅器８０からの出力Ｖは負方向に減少する。これより、トルクＴの方向及び大きさが検出される。 Next, the operation of the detection circuit of FIG. 3 will be described. High frequency current I generated from the oscillator 70 flows to the resistor _{R 1} and + 45 ° detection coil 21, flows out of the resistor _{R 2} and the resistor _{R 3.} When torque is not applied, zero point adjustment is performed so that the detection circuit is in an equilibrium state. As shown in FIG. 2, when a positive torque T is applied, the inductance L of the + 45 ° detection coil 21 increases by ΔL, and the output V from the lock-in amplifier 80 increases in the positive direction. On the other hand, when a negative torque is applied, the inductance L of the + 45 ° detection coil 21 decreases by ΔL, and the output V from the lock-in amplifier 80 decreases in the negative direction. From this, the direction and magnitude of the torque T are detected.

図３の検出回路によれば、＋４５°コイル２１と３つの抵抗器Ｒ_１、Ｒ_２、Ｒ_３のブリッジ回路のバランスをとることにより、更に、ロックイン増幅器８０により雑音が除去されるため、安定した精確なゼロ点調整を容易に行うことができるとともに、出力電圧の感度を高くすることができる。 According to the detection circuit of FIG. 3, noise is removed by the lock-in amplifier 80 by balancing the bridge circuit of the + 45 ° coil 21 and the three resistors R ₁ , R ₂ , and R ₃ . Stable and accurate zero point adjustment can be easily performed, and the sensitivity of the output voltage can be increased.

さらに、上述した磁歪式トルクセンサの構造によれば、＋４５°コイル２１により発生する磁束Φが−４５°方向に集中するため、出力信号の感度を高くすることができる。また、＋４５°コイル２１は磁性リング３１の周囲に巻かれており磁歪回転軸１０に対して回転対称であるため、出力信号は磁歪回転軸１０の回転角度に依存することがない。即ち、磁歪回転軸１０の回転に伴う出力信号のゼロ点変動を小さくすることができる。 Furthermore, according to the structure of the magnetostrictive torque sensor described above, the magnetic flux Φ generated by the + 45 ° coil 21 is concentrated in the −45 ° direction, so that the sensitivity of the output signal can be increased. Further, since the + 45 ° coil 21 is wound around the magnetic ring 31 and is rotationally symmetric with respect to the magnetostrictive rotating shaft 10, the output signal does not depend on the rotational angle of the magnetostrictive rotating shaft 10. That is, the zero point fluctuation of the output signal accompanying the rotation of the magnetostrictive rotating shaft 10 can be reduced.

なお、上述の第１実施例では、検出コイルが回転軸１０の軸Ｏに対して＋４５°傾き、磁性リングの非磁性部及び強磁性部が回転軸１０の軸Ｏに対して−４５°傾くとしたが、逆に、検出コイルが回転軸１０の軸Ｏに対して−４５°傾き、磁性リングの非磁性部及び強磁性部が回転軸１０の軸Ｏに対して＋４５°傾くとしても良い。 In the first embodiment described above, the detection coil is inclined + 45 ° with respect to the axis O of the rotating shaft 10, and the nonmagnetic portion and the ferromagnetic portion of the magnetic ring are inclined −45 ° with respect to the axis O of the rotating shaft 10. However, conversely, the detection coil may be inclined by −45 ° with respect to the axis O of the rotating shaft 10, and the nonmagnetic portion and the ferromagnetic portion of the magnetic ring may be inclined by + 45 ° with respect to the axis O of the rotating shaft 10. .

図４は、本発明の磁歪式トルクセンサの第２実施例を示す。第２実施例の磁歪式トルクセンサは磁歪特性を有する回転軸１０を有するが、第１実施例と相違して、回転軸１０の軸Ｏに対して＋４５°傾いたコイル２１（以下、単に「＋４５°コイル」と呼ぶ）が周囲に巻かれた磁性リング３１と、回転軸１０の軸Ｏに対して−４５°傾いたコイル２２（以下、単に「−４５°コイル」と呼ぶ）が周囲に巻かれた磁性リング３２とをそれぞれ回転軸１０の両端部に通して回転軸１０に同心状に配置する。更に、１つの磁性リング３１は、回転軸１０の軸Ｏに対して−４５°傾いた非磁性部３１ａ及び強磁性部３１ｂ（以下、それぞれ単に「−４５°非磁性部」及び「−４５°強磁性部」と呼ぶ）を併せ持つ複合磁性材料からなっており、図４に示すように、磁性リング３１は−４５°非磁性部３１ａ及び−４５°強磁性部３１ｂを円周方向に交互に配置した構造を有する。また、もう１つの磁性リング３２は、回転軸１０の軸Ｏに対して＋４５°傾いた非磁性部３２ａ及び強磁性部３２ｂ（以下、それぞれ単に「＋４５°非磁性部」及び「＋４５°強磁性部」と呼ぶ）を併せ持つ複合磁性材料からなっており、図４に示すように、磁性リング３２は＋４５°非磁性部３２ａ及び＋４５°強磁性部３２ｂを円周方向に交互に配置した構造を有する。ここで、−４５°非磁性部３１ａ及び＋４５°非磁性部３２ａは比透磁率が低いものが望ましく、−４５°強磁性部３１ｂ及び＋４５°強磁性部３２ｂは比透磁率が高いものが望ましい。また、−４５°非磁性部３１ａと−４５°強磁性部３１ｂ、及び＋４５°非磁性部３２ａと＋４５°強磁性部３２ｂの個数は４から２Ｎ（Ｎ＝２，３，４，…）である。また、＋４５°コイル２１と−４５°コイル２２の検出感度を高くするため、−４５°非磁性部３１ａ及び＋４５°非磁性部３２ａの面積はそれぞれ−４５°強磁性部３１ｂ及び＋４５°強磁性部３２ｂの面積より小さいことが好ましい。 FIG. 4 shows a second embodiment of the magnetostrictive torque sensor of the present invention. The magnetostrictive torque sensor of the second embodiment has a rotating shaft 10 having magnetostrictive characteristics. However, unlike the first embodiment, a coil 21 tilted by + 45 ° with respect to the axis O of the rotating shaft 10 (hereinafter simply referred to as “ A magnetic ring 31 wound around (around + 45 ° coil) and a coil 22 tilted at −45 ° with respect to the axis O of the rotating shaft 10 (hereinafter simply referred to as “−45 ° coil”) The wound magnetic rings 32 are respectively concentrically arranged on the rotating shaft 10 through both ends of the rotating shaft 10. Further, one magnetic ring 31 includes a nonmagnetic portion 31a and a ferromagnetic portion 31b (hereinafter simply referred to as “−45 ° nonmagnetic portion” and “−45 °, respectively” inclined by −45 ° with respect to the axis O of the rotating shaft 10, respectively. As shown in FIG. 4, the magnetic ring 31 includes a −45 ° nonmagnetic portion 31 a and a −45 ° ferromagnetic portion 31 b alternately in the circumferential direction. It has an arranged structure. The other magnetic ring 32 includes a non-magnetic portion 32a and a ferromagnetic portion 32b (hereinafter simply referred to as “+ 45 ° non-magnetic portion” and “+ 45 ° ferromagnetic”, respectively) inclined + 45 ° with respect to the axis O of the rotating shaft 10. As shown in FIG. 4, the magnetic ring 32 has a structure in which + 45 ° nonmagnetic portions 32a and + 45 ° ferromagnetic portions 32b are alternately arranged in the circumferential direction. Have. Here, the −45 ° nonmagnetic portion 31a and the + 45 ° nonmagnetic portion 32a desirably have low relative permeability, and the −45 ° ferromagnetic portion 31b and the + 45 ° ferromagnetic portion 32b desirably have high relative permeability. . The number of −45 ° nonmagnetic portions 31a and −45 ° ferromagnetic portions 31b, and + 45 ° nonmagnetic portions 32a and + 45 ° ferromagnetic portions 32b is 4 to 2N (N = 2, 3, 4,...). is there. In order to increase the detection sensitivity of the + 45 ° coil 21 and the −45 ° coil 22, the areas of the −45 ° nonmagnetic portion 31a and the + 45 ° nonmagnetic portion 32a are −45 ° ferromagnetic portion 31b and + 45 ° ferromagnetic portion, respectively. It is preferable that it is smaller than the area of the part 32b.

次に、図５を参照して、図４の磁歪式トルクセンサの動作について説明する。＋４５°コイル２１に電流Iを流すと＋４５°コイル２１により発生する磁束Φは磁性リング３１の−４５°非磁性部３１ａ（非磁性部３１ａは−４５°方向に弱く磁化される）及び−４５°強磁性部３１ｂを通るため、図５に示すように磁束Φは強制的に回転軸１０の軸Ｏに対して−４５°傾いて回転軸１０を通る。よって、回転軸１０を通る磁束Φは磁化容易方向＋σ方向（張力方向）に集中して張力方向の比透磁率が大きくなるため、＋４５°コイル２１のインダクタンスは大きくなる。同様に、−４５°コイル２２に電流Iを流すと−４５°コイル２２により発生する磁束Φは磁性リング３２の＋４５°非磁性部３２ａ（非磁性部３２ａは＋４５°方向に弱く磁化される）及び＋４５°強磁性部３２ｂを通るため、図５に示すように磁束Φは強制的に回転軸１０の軸Ｏに対して＋４５°傾いて回転軸１０を通る。よって、回転軸１０を通る磁束Φは磁化困難方向−σ方向（圧縮方向）に集中して圧縮方向の比透磁率が小さくなるため、−４５°コイル２２のインダクタンスは小さくなる。 Next, the operation of the magnetostrictive torque sensor of FIG. 4 will be described with reference to FIG. When the current I is supplied to the + 45 ° coil 21, the magnetic flux Φ generated by the + 45 ° coil 21 is −45 ° nonmagnetic portion 31a of the magnetic ring 31 (the nonmagnetic portion 31a is weakly magnetized in the −45 ° direction) and −45. The magnetic flux Φ is forced to pass through the rotating shaft 10 by being inclined by −45 ° with respect to the axis O of the rotating shaft 10 as shown in FIG. Therefore, the magnetic flux Φ passing through the rotating shaft 10 is concentrated in the easy magnetization direction + σ direction (tensile direction) and the relative permeability in the tension direction is increased, so that the inductance of the + 45 ° coil 21 is increased. Similarly, when the current I is supplied to the −45 ° coil 22, the magnetic flux Φ generated by the −45 ° coil 22 is the + 45 ° nonmagnetic portion 32a of the magnetic ring 32 (the nonmagnetic portion 32a is weakly magnetized in the + 45 ° direction). Since the magnetic flux passes through the + 45 ° ferromagnetic portion 32b, the magnetic flux Φ is forced to pass through the rotating shaft 10 with an inclination of + 45 ° with respect to the axis O of the rotating shaft 10, as shown in FIG. Therefore, the magnetic flux Φ passing through the rotating shaft 10 is concentrated in the magnetization difficult direction −σ direction (compression direction) and the relative permeability in the compression direction is reduced, so that the inductance of the −45 ° coil 22 is reduced.

図６は、上述した第２実施例の＋４５°コイル２１と−４５°コイル２２の電気特性から磁歪回転軸１０に印加されるトルクを検出するための検出回路である。＋４５°コイル２１と−４５°コイル２２と、２つの抵抗器Ｒ_１、Ｒ_２（Ｒ_１＝Ｒ_２＝１０Ω）を用いて、図６に示すようなブリッジ回路を構成する。そして、直列接続された＋４５°検出コイル２１と抵抗器Ｒ_１、直列接続された−４５°検出コイル２２と抵抗器Ｒ_２との両端に回路を駆動する発振器７０を接続し、＋４５°検出コイル２１と抵抗器Ｒ_１の間、及び直列接続された−４５°検出コイル２２と抵抗器Ｒ_２の間に、トルク印加時にブリッジ回路から発生する差動信号を検出・増幅して出力するロックイン増幅器８０を接続する。 FIG. 6 shows a detection circuit for detecting the torque applied to the magnetostrictive rotating shaft 10 from the electrical characteristics of the + 45 ° coil 21 and the −45 ° coil 22 of the second embodiment described above. A bridge circuit as shown in FIG. 6 is configured by using the + 45 ° coil 21 and the −45 ° coil 22 and the two resistors R ₁ and R ₂ (R ₁ = R ₂ = 10Ω). Then, a + 45 ° detection coil 21 and a resistor R ₁ connected in series, an oscillator 70 for driving a circuit is connected to both ends of the −45 ° detection coil 22 and the resistor R ₂ connected in series, and a + 45 ° detection coil. A lock-in that detects and amplifies and outputs a differential signal generated from the bridge circuit when torque is applied between the resistor 21 and the resistor R ₁ and between the -45 ° detection coil 22 and the resistor R ₂ connected in series. An amplifier 80 is connected.

次に、図６の検出回路の動作について説明する。発振器７０から発生する高周波数電流Ｉが＋４５°検出コイル２１と−４５°検出コイル２２に流入し、抵抗器Ｒ_１と抵抗器Ｒ_２から流出する。トルクが印加されていないとき、検出回路が平衡状態になるようにゼロ点調整を行う。図６に示すように、正トルクＴが印加されるとき、＋４５°検出コイル２１のインダクタンスＬがΔＬ増加し、−４５°検出コイル２２のインダクタンスＬがΔＬ減少し、ロックイン増幅器８０からの出力Ｖは正方向に増加する。それに対して、負トルクが印加されるとき、＋４５°検出コイル２１のインダクタンスＬがΔＬ減少し、−４５°検出コイル２２のインダクタンスＬがΔＬ増加し、ロックイン増幅器８０からの出力Ｖは負方向に減少する。これより、トルクＴの方向及び大きさが検出される。 Next, the operation of the detection circuit of FIG. 6 will be described. Flowing high frequency current I + 45 ° detection coil 21 generated from the oscillator 70 and the -45 ° detection coil 22, flows out resistor _{R 1} from the resistor _{R 2.} When torque is not applied, zero point adjustment is performed so that the detection circuit is in an equilibrium state. As shown in FIG. 6, when a positive torque T is applied, the inductance L of the + 45 ° detection coil 21 increases by ΔL, the inductance L of the −45 ° detection coil 22 decreases by ΔL, and the output from the lock-in amplifier 80. V increases in the positive direction. On the other hand, when a negative torque is applied, the inductance L of the + 45 ° detection coil 21 decreases by ΔL, the inductance L of the −45 ° detection coil 22 increases by ΔL, and the output V from the lock-in amplifier 80 is in the negative direction. To decrease. From this, the direction and magnitude of the torque T are detected.

図６の検出回路によれば、＋４５°コイル２１と−４５°コイル２２と、２つの抵抗器Ｒ_１、Ｒ_２のブリッジ回路のバランスをとることにより、更に、ロックイン増幅器８０により雑音が除去されるため、安定した精確なゼロ点調整を容易に行うことができるとともに、出力電圧の感度を高くすることができる。 According to the detection circuit of FIG. 6, noise is removed by the lock-in amplifier 80 by balancing the bridge circuit of the + 45 ° coil 21 and the −45 ° coil 22 and the two resistors R ₁ and R _2. Therefore, stable and accurate zero point adjustment can be easily performed, and the sensitivity of the output voltage can be increased.

さらに、第２実施例の磁歪式トルクセンサの構造によれば、＋４５°コイル２１と−４５°コイル２２により発生する磁束Φがそれぞれ−４５°方向と＋４５°方向に集中するため、出力信号の感度を高くすることができる。また、＋４５°コイル２１と−４５°コイル２２はそれぞれ磁性リング３１と３２の周囲に巻かれており磁歪回転軸１０に対して回転対称であるため、出力信号は磁歪回転軸１０の回転角度に依存することがない。即ち、磁歪回転軸１０の回転に伴う出力信号のゼロ点変動を小さくすることができる。 Further, according to the structure of the magnetostrictive torque sensor of the second embodiment, the magnetic flux Φ generated by the + 45 ° coil 21 and the −45 ° coil 22 is concentrated in the −45 ° direction and the + 45 ° direction, respectively. Sensitivity can be increased. Since the + 45 ° coil 21 and the −45 ° coil 22 are wound around the magnetic rings 31 and 32 respectively and are rotationally symmetric with respect to the magnetostrictive rotating shaft 10, the output signal is at the rotational angle of the magnetostrictive rotating shaft 10. There is no dependence. That is, the zero point fluctuation of the output signal accompanying the rotation of the magnetostrictive rotating shaft 10 can be reduced.

図７（ａ）は、磁歪特性を有する回転軸１０の軸Ｏ（図示せず）に対して＋４５°傾いたコイル２１（以下、単に「＋４５°コイル」と呼ぶ）がそれぞれに巻かれた半円筒磁心ペア４１、４１を磁歪回転軸１０に装着した本発明の磁歪式トルクセンサの第３実施例を示す。ここで、各半円筒磁心４１、４１は、磁歪特性を有する回転軸１０の軸Ｏ（図示せず）に対して−４５°傾いた非磁性部４１ａ及び強磁性部４１ｂ（以下、それぞれ単に「−４５°非磁性部」及び「−４５°強磁性部」と呼ぶ）を併せ持つ複合磁性材料からなる。図７（ｂ）は、（ａ）の−４５°非磁性部４１ａにおける−４５°切断部４１Ａを含む半円筒磁心ペア４１、４１の軸に垂直な方向から見た部分拡大平面図である。第３実施例では、第１実施例と相違して、磁性リングを、切断部４１Ａで示すように、切断方向が−４５°非磁性部４１ａと−４５°強磁性部４１ｂの傾く方向と同じであるように、その直径上の−４５°非磁性部４１ａで２つの半円筒磁心４１，４１に分割する。＋４５°コイル２１は、２つの半円筒磁心４１，４１のそれぞれに、その一方の切断端面の４５°の角の所から、−４５°非磁性部４１ａ及び−４５°強磁性部４１ｂに直交して、他方の切断端面の４５°の角の所まで巻く。そして、２つの半円筒磁心４１，４１を磁歪回転軸１０の周囲に同心状に緊密に対向配置して、磁歪式トルクセンサを構成する。 FIG. 7A shows a half in which coils 21 (hereinafter simply referred to as “+ 45 ° coils”) inclined by + 45 ° with respect to the axis O (not shown) of the rotary shaft 10 having magnetostrictive characteristics are wound. A third embodiment of the magnetostrictive torque sensor according to the present invention in which cylindrical magnetic core pairs 41 and 41 are mounted on the magnetostrictive rotating shaft 10 will be described. Here, each of the semi-cylindrical magnetic cores 41 and 41 includes a non-magnetic portion 41a and a ferromagnetic portion 41b (hereinafter simply referred to as “a”) inclined by −45 ° with respect to the axis O (not shown) of the rotating shaft 10 having magnetostrictive characteristics. It is made of a composite magnetic material having both “−45 ° nonmagnetic part” and “−45 ° ferromagnetic part”. FIG. 7B is a partially enlarged plan view seen from a direction perpendicular to the axis of the semi-cylindrical core pairs 41 and 41 including the −45 ° cut portion 41A in the −45 ° nonmagnetic portion 41a of FIG. In the third embodiment, unlike the first embodiment, the cutting direction of the magnetic ring is the same as the tilting direction of the −45 ° nonmagnetic portion 41a and the −45 ° ferromagnetic portion 41b as shown by the cutting portion 41A. As shown in the figure, the semi-cylindrical magnetic cores 41 and 41 are divided by the −45 ° nonmagnetic part 41a on the diameter. The + 45 ° coil 21 is orthogonal to the −45 ° nonmagnetic portion 41a and the −45 ° ferromagnetic portion 41b from each of the two semi-cylindrical magnetic cores 41 and 41 from the 45 ° corner of one cut end surface thereof. Then, wrap up to the 45 ° corner of the other cut end face. The two semi-cylindrical magnetic cores 41 and 41 are arranged concentrically and closely around the magnetostrictive rotating shaft 10 to constitute a magnetostrictive torque sensor.

なお、図７の磁歪式トルクセンサの動作原理については、図２で説明した動作原理と同様であるので説明は省略する。 The operation principle of the magnetostrictive torque sensor in FIG. 7 is the same as the operation principle described in FIG.

図８は、上述した第３実施例の２つの＋４５°コイル２１，２１の電気特性から磁歪回転軸１０に印加されるトルクを検出するための検出回路である。２つの＋４５°コイル２１，２１と、２つの抵抗器Ｒ_１、Ｒ_２（Ｒ_１＝Ｒ_２＝１０Ω）を用いて、図８に示すようなブリッジ回路を構成する。そして、２つの直列接続された＋４５°コイル２１，２１、直列接続抵抗器Ｒ_１とＲ_２との両端に回路を駆動する発振器７０を接続し、直列接続された２つの＋４５°コイル２１の間、及び直列接続抵抗器Ｒ_１とＲ_２の間に、トルク印加時にブリッジ回路から発生する差動信号を検出・増幅して出力するロックイン増幅器８０を接続する。 FIG. 8 shows a detection circuit for detecting the torque applied to the magnetostrictive rotating shaft 10 from the electrical characteristics of the two + 45 ° coils 21 and 21 of the third embodiment. A bridge circuit as shown in FIG. 8 is configured by using two + 45 ° coils 21 and 21 and two resistors R ₁ and R ₂ (R ₁ = R ₂ = 10Ω). Then, two + 45 ° coils 21 and 21 connected in series and an oscillator 70 for driving a circuit are connected to both ends of the series connected resistors R ₁ and R _2, and between the two + 45 ° coils 21 connected in series. The lock-in amplifier 80 is connected between the series-connected resistors R ₁ and R ₂ for detecting and amplifying a differential signal generated from the bridge circuit when torque is applied.

次に、図８の検出回路の動作について説明する。発振器７０から発生する高周波数電流Ｉが上側の＋４５°検出コイル２１と抵抗器Ｒ_１に流入し、下側の＋４５°検出コイル２１と抵抗器Ｒ_２から流出する。トルクが印加されていないとき、検出回路が平衡状態になるようにゼロ点調整を行う。図８に示すように、正トルクＴが印加されるとき、上側の＋４５°検出コイル２１のインダクタンスＬがΔＬ増加し、下側の＋４５°検出コイル２１のインダクタンスＬがΔＬ減少し、ロックイン増幅器８０からの出力Ｖは正方向に増加する。それに対して、負トルクが印加されるとき、上側の＋４５°検出コイル２１のインダクタンスＬがΔＬ減少し、下側の＋４５°検出コイル２１のインダクタンスＬがΔＬ増加し、ロックイン増幅器８０からの出力Ｖは負方向に減少する。これより、トルクＴの方向及び大きさが検出される。 Next, the operation of the detection circuit of FIG. 8 will be described. High frequency current I generated from the oscillator 70 flows to the upper of + 45 ° detection coil 21 to the resistor R _1, flows out below the + 45 ° detection coil 21 from the resistor R _2. When torque is not applied, zero point adjustment is performed so that the detection circuit is in an equilibrium state. As shown in FIG. 8, when a positive torque T is applied, the inductance L of the upper + 45 ° detection coil 21 increases by ΔL, and the inductance L of the lower + 45 ° detection coil 21 decreases by ΔL. The output V from 80 increases in the positive direction. On the other hand, when a negative torque is applied, the inductance L of the upper + 45 ° detection coil 21 decreases by ΔL, the inductance L of the lower + 45 ° detection coil 21 increases by ΔL, and the output from the lock-in amplifier 80 V decreases in the negative direction. From this, the direction and magnitude of the torque T are detected.

図８の検出回路によれば、２つの＋４５°コイル２１，２１と、２つの抵抗器Ｒ_１、Ｒ_２のブリッジ回路のバランスをとることにより、更に、ロックイン増幅器８０により雑音が除去されるため、安定した精確なゼロ点調整を容易に行うことができるとともに、出力電圧の感度を高くすることができる。 According to the detection circuit of FIG. 8, noise is further removed by the lock-in amplifier 80 by balancing the bridge circuit of the two + 45 ° coils 21 and 21 and the two resistors R ₁ and R _2. Therefore, stable and accurate zero point adjustment can be easily performed, and the sensitivity of the output voltage can be increased.

さらに、第３実施例の磁歪式トルクセンサの構造によれば、２つの直列接続された＋４５°コイル２１，２１により発生する磁束Φが−４５°方向に集中するため、出力信号の感度を高くすることができる。また、２つの直列接続された＋４５°コイル２１，２１は、第１実施例と同様に磁歪回転軸１０に対してリング形軸回転対称検出コイルと同じ働きをするため、第１実施例と同様に磁歪回転軸１０に対して回転対称であるため、出力信号は磁歪回転軸１０の回転角度に依存することがない。即ち、磁歪回転軸１０の回転に伴う出力信号のゼロ点変動を小さくすることができる。しかも、第３実施例の磁歪式トルクセンサは２つの半円筒磁心４１，４１に分割されるため、第１実施例に比較して容易に磁歪回転軸１０に装着することができる。 Furthermore, according to the structure of the magnetostrictive torque sensor of the third embodiment, since the magnetic flux Φ generated by the two + 45 ° coils 21 and 21 connected in series is concentrated in the −45 ° direction, the sensitivity of the output signal is increased. can do. Further, since the two + 45 ° coils 21 and 21 connected in series function in the same manner as the ring-shaped axial rotation symmetry detection coil with respect to the magnetostrictive rotating shaft 10 as in the first embodiment, they are the same as in the first embodiment. The output signal does not depend on the rotation angle of the magnetostrictive rotating shaft 10 because it is rotationally symmetric with respect to the magnetostrictive rotating shaft 10. That is, the zero point fluctuation of the output signal accompanying the rotation of the magnetostrictive rotating shaft 10 can be reduced. Moreover, since the magnetostrictive torque sensor of the third embodiment is divided into two semi-cylindrical cores 41, 41, the magnetostrictive torque sensor can be easily attached to the magnetostrictive rotating shaft 10 as compared with the first embodiment.

図９は、本発明の磁歪式トルクセンサの第４実施例を示す。第４実施例では、第２実施例の磁性リング３１及び３２をそれぞれ、第３実施例のように、−４５°切断部４１Ａ及び＋４５°切断部４２Ａで示すように、その直径上の−４５°非磁性部４１ａ及び＋４５°非磁性部４２ａの位置で、−４５°非磁性部４１ａ及び＋４５°非磁性部４２ａの傾き方向に沿って２つの半円筒磁心ペア４１，４１及び４２，４２に分割して、半円筒磁心４１，４１及び４２，４２のそれぞれに＋４５°コイル２１，２１及び−４５°コイル２２，２２を巻回する。 FIG. 9 shows a fourth embodiment of the magnetostrictive torque sensor of the present invention. In the fourth embodiment, as in the third embodiment, the magnetic rings 31 and 32 of the second embodiment are each −45 on the diameter as indicated by the −45 ° cut portion 41A and the + 45 ° cut portion 42A. At the positions of the nonmagnetic portion 41a and the + 45 ° nonmagnetic portion 42a, two semi-cylindrical magnetic core pairs 41, 41 and 42, 42 are formed along the inclination direction of the −45 ° nonmagnetic portion 41a and the + 45 ° nonmagnetic portion 42a. Dividing and winding the + 45 ° coils 21 and 21 and the −45 ° coils 22 and 22 around the semi-cylindrical cores 41, 41 and 42, 42, respectively.

なお、図９の磁歪式トルクセンサの動作原理については、図５で説明した動作原理と同様であるので説明は省略する。 The operation principle of the magnetostrictive torque sensor in FIG. 9 is the same as the operation principle described in FIG.

図１０は、上述した第４実施例の２つの＋４５°コイル２１，２１及び２つの−４５°コイル２２，２２の電気特性から磁歪回転軸１０に印加されるトルクを検出するための検出回路である。２つの＋４５°コイル２１，２１及び２つの−４５°コイル２２，２２を用いて、図１０に示すようなブリッジ回路を構成する。そして、２つの直列接続された＋４５°コイル２１と２１、２つの直列接続された−４５°コイル２２と２２の両端に回路を駆動する発振器７０を接続し、２つの直列接続された＋４５°検出コイル２１と２１の間、及び２つの直列接続された−４５°コイル２２と２２の間に、トルク印加時にブリッジ回路から発生する差動信号を検出・増幅して出力するロックイン増幅器８０を接続する。 FIG. 10 is a detection circuit for detecting the torque applied to the magnetostrictive rotating shaft 10 from the electrical characteristics of the two + 45 ° coils 21 and 21 and the two −45 ° coils 22 and 22 of the fourth embodiment. is there. A bridge circuit as shown in FIG. 10 is configured by using the two + 45 ° coils 21 and 21 and the two −45 ° coils 22 and 22. Then, two series-connected + 45 ° coils 21 and 21 and two series-connected −45 ° coils 22 and 22 are connected to an oscillator 70 for driving the circuit, and two series-connected + 45 ° detections are made. A lock-in amplifier 80 that detects and amplifies and outputs a differential signal generated from the bridge circuit when torque is applied is connected between the coils 21 and 21 and between the two -45 ° coils 22 and 22 connected in series. To do.

次に、図１０の検出回路の動作について説明する。発振器７０から発生する高周波数電流Ｉが上側の＋４５°検出コイル２１と−４５°検出コイル２２に流入し、下側の＋４５°検出コイル２１と−４５°検出コイル２２から流出する。トルクが印加されていないとき、検出回路が平衡状態になるようにゼロ点調整を行う。図１０に示すように、正トルクＴが印加されるとき、左上側の＋４５°検出コイル２１と右下側のと−４５°検出コイル２２のインダクタンスＬがΔＬ増加し、左下側の＋４５°検出コイル２１と右上側の−４５°検出コイル２２のインダクタンスＬがΔＬ減少し、ロックイン増幅器８０からの出力Ｖは正方向に増加する。それに対して、負トルクが印加されるとき、左上側の＋４５°検出コイル２１と右下側の−４５°検出コイル２２のインダクタンスＬがΔＬ減少し、左下側の＋４５°検出コイル２１と右上側のと−４５°検出コイル２２のインダクタンスＬがΔＬ増加し、ロックイン増幅器８０からの出力Ｖは負方向に減少する。これより、トルクＴの方向及び大きさが検出される。 Next, the operation of the detection circuit of FIG. 10 will be described. The high frequency current I generated from the oscillator 70 flows into the upper + 45 ° detection coil 21 and −45 ° detection coil 22 and flows out from the lower + 45 ° detection coil 21 and −45 ° detection coil 22. When torque is not applied, zero point adjustment is performed so that the detection circuit is in an equilibrium state. As shown in FIG. 10, when a positive torque T is applied, the inductance L of the + 45 ° detection coil 21 on the upper left side and the −45 ° detection coil 22 on the lower right side increases by ΔL, and + 45 ° detection on the lower left side is detected. The inductance L of the coil 21 and the −45 ° detection coil 22 on the upper right side decreases by ΔL, and the output V from the lock-in amplifier 80 increases in the positive direction. On the other hand, when a negative torque is applied, the inductance L of the + 45 ° detection coil 21 on the upper left side and the −45 ° detection coil 22 on the lower right side decreases by ΔL, and the + 45 ° detection coil 21 on the lower left side and the upper right side. In this case, the inductance L of the −45 ° detection coil 22 increases by ΔL, and the output V from the lock-in amplifier 80 decreases in the negative direction. From this, the direction and magnitude of the torque T are detected.

図１０の検出回路によれば、２つの＋４５°コイル２１，２１及び２つの−４５°コイル２２，２２のブリッジ回路のバランスをとることにより、更に、ロックイン増幅器８０により雑音が除去されるため、安定した精確なゼロ点調整を容易に行うことができるとともに、出力電圧の感度を高くすることができる。 According to the detection circuit of FIG. 10, noise is removed by the lock-in amplifier 80 by balancing the bridge circuit of the two + 45 ° coils 21 and 21 and the two −45 ° coils 22 and 22. Thus, stable and accurate zero point adjustment can be easily performed, and the sensitivity of the output voltage can be increased.

さらに、第４実施例の磁歪式トルクセンサの構造によれば、２つの直列接続された＋４５°コイル２１，２１及び２つの直列接続された−４５°コイル２２，２２により発生する磁束Φがそれぞれ−４５°方向と＋４５°方向に集中するため、出力信号の感度を高くすることができる。また、２つの直列接続された＋４５°コイル２１，２１及び２つの直列接続された−４５°コイル２２，２２は、第２実施例と同様に磁歪回転軸１０に対してリング形軸回転対称検出コイルと同じ働きをするため、第２実施例と同様に磁歪回転軸１０に対して回転対称であるため、出力信号は磁歪回転軸１０の回転角度に依存することがない。即ち、磁歪回転軸１０の回転に伴う出力信号のゼロ点変動を小さくすることができる。しかも、第４実施例の磁歪式トルクセンサは２つの半円筒磁心４１，４１及び４２，４２に分割されるため、第２実施例に比較して容易に磁歪回転軸１０に装着することができる。更に、検出コイルの数は４つあるため、検出コイルのブリッジ回路の接続が容易であり、外部回路を要しないでブリッジ回路が組める。 Furthermore, according to the structure of the magnetostrictive torque sensor of the fourth embodiment, the magnetic fluxes Φ generated by the two + 45 ° coils 21 and 21 connected in series and the −45 ° coils 22 and 22 connected in series are respectively Since the concentration is in the −45 ° direction and the + 45 ° direction, the sensitivity of the output signal can be increased. Further, the two + 45 ° coils 21 and 21 connected in series and the two −45 ° coils 22 and 22 connected in series are detected by the ring-shaped axis rotation symmetry with respect to the magnetostrictive rotation axis 10 as in the second embodiment. Since it functions in the same manner as the coil, it is rotationally symmetric with respect to the magnetostrictive rotating shaft 10 as in the second embodiment, so that the output signal does not depend on the rotational angle of the magnetostrictive rotating shaft 10. That is, the zero point fluctuation of the output signal accompanying the rotation of the magnetostrictive rotating shaft 10 can be reduced. Moreover, since the magnetostrictive torque sensor of the fourth embodiment is divided into two semi-cylindrical magnetic cores 41, 41 and 42, 42, it can be easily attached to the magnetostrictive rotating shaft 10 as compared with the second embodiment. . Furthermore, since there are four detection coils, the connection of the bridge circuit of the detection coil is easy, and the bridge circuit can be assembled without requiring an external circuit.

本発明の磁歪式トルクセンサの第１実施例を示す。1 shows a first embodiment of a magnetostrictive torque sensor of the present invention. 図１の磁歪式トルクセンサの動作原理を示す模式図である。It is a schematic diagram which shows the operation | movement principle of the magnetostrictive torque sensor of FIG. 図１の磁歪式トルクセンサにより、磁歪回転軸に印加されるトルクを検出するための検出回路である。2 is a detection circuit for detecting torque applied to a magnetostrictive rotating shaft by the magnetostrictive torque sensor of FIG. 1. 本発明の磁歪式トルクセンサの第２実施例を示す。2 shows a second embodiment of the magnetostrictive torque sensor of the present invention. 図４の磁歪式トルクセンサの動作原理を示す模式図である。It is a schematic diagram which shows the operation | movement principle of the magnetostrictive torque sensor of FIG. 図４の磁歪式トルクセンサにより、磁歪回転軸に印加されるトルクを検出するための検出回路である。5 is a detection circuit for detecting torque applied to the magnetostrictive rotating shaft by the magnetostrictive torque sensor of FIG. 4. （ａ）は、それぞれに＋４５°コイルが巻かれた半円筒磁心ペアを磁歪回転軸に装着した本発明の磁歪式トルクセンサの第３実施例を示す。（ｂ）は、（ａ）の−４５°非磁性部における−４５°切断部を含む半円筒磁心ペアの軸に垂直な方向から見た部分拡大平面図である。(A) shows a third embodiment of a magnetostrictive torque sensor according to the present invention in which a pair of semi-cylindrical magnetic cores each wound with a + 45 ° coil is mounted on a magnetostrictive rotating shaft. (B) is the elements on larger scale seen from the direction perpendicular | vertical to the axis | shaft of the semi-cylindrical magnetic core pair containing the -45 degree cut part in the -45 degree nonmagnetic part of (a). 図７の磁歪式トルクセンサにより、磁歪回転軸に印加されるトルクを検出するための検出回路である。8 is a detection circuit for detecting torque applied to the magnetostrictive rotating shaft by the magnetostrictive torque sensor of FIG. 本発明の第４実施例による、２つの半円筒磁心ペアを磁歪回転軸に装着した磁歪式トルクセンサの模式図である。FIG. 10 is a schematic diagram of a magnetostrictive torque sensor having two semi-cylindrical magnetic core pairs mounted on a magnetostrictive rotating shaft according to a fourth embodiment of the present invention. 図９の磁歪式トルクセンサにより、磁歪回転軸に印加されるトルクを検出するための検出回路である。10 is a detection circuit for detecting torque applied to the magnetostrictive rotating shaft by the magnetostrictive torque sensor of FIG. 9. （ａ）及び（ｂ）はそれぞれ従来の磁歪式トルクセンサの概略図である。(A) And (b) is the schematic of the conventional magnetostrictive torque sensor, respectively.

Explanation of symbols

１０磁歪回転軸
２１＋４５°コイル
２２ −４５°コイル
３１、３２磁性リング
４１、４２半円筒磁心
３１ａ、４１ａ −４５°非磁性部
３１ｂ、４１ｂ −４５°強磁性部
３２ａ、４２ａ＋４５°非磁性部
３２ｂ、４２ｂ＋４５°強磁性部
４１Ａ、４２Ａ切断部
７０発振器
８０ロックイン増幅器 10 Magnetostrictive rotating shaft 21 + 45 ° coil 22 −45 ° coil 31, 32 Magnetic rings 41, 42 Semi-cylindrical magnetic core 31a, 41a −45 ° nonmagnetic part 31b, 41b −45 ° ferromagnetic part 32a, 42a + 45 ° nonmagnetic part 32b, 42b + 45 ° ferromagnetic part 41A, 42A cutting part 70 oscillator 80 lock-in amplifier

Claims

A rotating shaft having magnetostrictive characteristics that rotates around a central axis, and a coil that is arranged coaxially with the rotating shaft while having a predetermined distance from the outer periphery of the rotating shaft, is wound. In a magnetostrictive torque sensor with a magnetic ring,
The magnetic ring is formed of a ferromagnetic portion and a non-magnetic portion that are alternately arranged in a circumferential direction inclined by 45 ° with respect to the central axis,
The magnetostrictive torque sensor according to claim 1, wherein the coil is wound in a direction orthogonal to an inclination direction of the ferromagnetic portion and the nonmagnetic portion.

In order to detect a change in magnetic flux in the tension direction of the rotating shaft, the magnetic ring is inclined in the tension direction of the rotating shaft and alternately arranged in the circumferential direction and tension detecting ferromagnetic portions. In order to detect a change in magnetic flux in the compression direction of the rotating shaft, the first magnetic ring formed from a non-magnetic portion is alternately arranged in the circumferential direction inclining in the compressing direction of the rotating shaft. A second magnetic ring formed from a compression detecting ferromagnetic portion and a compression detecting non-magnetic portion;
The coil includes a first coil wound around the first magnetic ring in a compression direction, and a second coil wound around the second magnetic ring in a tension direction. The magnetostrictive torque sensor according to claim 1, further comprising:

The magnetostrictive torque sensor according to claim 1, wherein the magnetic ring has an area of the nonmagnetic portion smaller than an area of the ferromagnetic portion.

The said magnetic ring contains the semi-cylindrical magnetic core divided into 2 along the inclination direction of the said nonmagnetic part in the position of the said nonmagnetic part, The Claim 1 characterized by the above-mentioned. Magnetostrictive torque sensor.

5. The magnetostrictive torque sensor according to claim 4, wherein a coil is wound independently on each of the two half-cylindrical magnetic cores.