JPH10339678A - Torque sensor - Google Patents
Torque sensorInfo
- Publication number
- JPH10339678A JPH10339678A JP14951897A JP14951897A JPH10339678A JP H10339678 A JPH10339678 A JP H10339678A JP 14951897 A JP14951897 A JP 14951897A JP 14951897 A JP14951897 A JP 14951897A JP H10339678 A JPH10339678 A JP H10339678A
- Authority
- JP
- Japan
- Prior art keywords
- shaft
- magnetostrictive material
- torque sensor
- magnetic flux
- magnetostrictive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、被検出軸に作用す
るトルクを歪み磁気特性を利用して検出する磁歪式のト
ルクセンサに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive torque sensor for detecting a torque acting on a shaft to be detected by utilizing a strained magnetic characteristic.
【０００２】[0002]
【従来の技術】この種の磁歪式のトルクセンサは、シャ
フトの外周面に固定された磁歪材がシャフトに働くトル
クによって捻じれて歪むことによりその透磁率がトルク
に応じて変化し、この透磁率変化に応じた磁束変化に基
づいて検出用コイルに誘導される誘導起電力からトルク
を検出するようになっている（例えば特開平５−１１８
９３８号公報、特開昭５９−７７３２６号公報等）。2. Description of the Related Art In a magnetostrictive torque sensor of this type, a magnetostrictive material fixed to an outer peripheral surface of a shaft is twisted and distorted by a torque acting on the shaft, so that its magnetic permeability changes in accordance with the torque. A torque is detected from an induced electromotive force induced in the detection coil based on a change in magnetic flux corresponding to a change in magnetic susceptibility (for example, Japanese Patent Laid-Open No. 5-118)
938, JP-A-59-77326, etc.).
【０００３】従来、シャフトに磁歪材を固定する取着構
造には、図１３に示す非トーションバー方式と、図１４
に示すトーションバー方式とが知られていた。非トーシ
ョンバー方式では、図１３（ａ）に示すようにシャフト
５１の外周面に磁歪スリーブ５２を直接外嵌する構造
と、図１３（ｂ）に示すようにシャフト５１に中間スリ
ーブ５３を介して磁歪材５４を外嵌させる構造とがあ
る。中間スリーブ５３は、磁歪材５４がシャフト５１に
対して心出しされる程度にその加工精度を厳しくしてお
くことで、トルクセンサを使用するユーザに対してシャ
フト５１の加工精度を厳しく要求しなくて済むように使
用される。また、図１４に示すトーションバー方式で
は、シャフト５１の径を細くしたくびれ部５１ａに磁歪
スリーブ５２が外嵌されている。くびれ部５１ａはシャ
フト５１の剛性を小さくすることを目的に形成されるも
ので、くびれ部５１ａを形成することで一定トルクに対
する磁歪スリーブ５２の歪み率を大きくでき、トルクセ
ンサの検出感度を向上させることができる。Conventionally, a mounting structure for fixing a magnetostrictive material to a shaft includes a non-torsion bar system shown in FIG.
The torsion bar method shown in FIG. In the non-torsion bar system, a structure in which the magnetostrictive sleeve 52 is directly fitted on the outer peripheral surface of the shaft 51 as shown in FIG. 13A, and a structure in which the shaft 51 is interposed on the shaft 51 through the intermediate sleeve 53 as shown in FIG. There is a structure in which the magnetostrictive material 54 is externally fitted. The intermediate sleeve 53 has a strict machining accuracy to the extent that the magnetostrictive material 54 is centered with respect to the shaft 51, so that the user using the torque sensor does not strictly require the machining accuracy of the shaft 51. Used to save money. Further, in the torsion bar system shown in FIG. 14, a magnetostrictive sleeve 52 is externally fitted to a narrow portion 51a in which the diameter of the shaft 51 is reduced. The constricted portion 51a is formed for the purpose of reducing the rigidity of the shaft 51. By forming the constricted portion 51a, the distortion rate of the magnetostrictive sleeve 52 with respect to a constant torque can be increased, and the detection sensitivity of the torque sensor is improved. be able to.
【０００４】[0004]
【発明が解決しようとする課題】ところで、磁歪材（磁
歪スリーブ）５２，５４を通る有効磁束は、シャフト５
１、中間スリーブ５３及び磁歪材（磁歪スリーブ）５
２，５４の総断面積に対する磁歪材５２，５４の占める
断面積比率（有効断面積）に依存する。図１３に示した
非トーションバー方式では、シャフト５１の断面積比率
が大きく磁歪材（磁歪スリーブ）５２，５４の有効断面
積が小さいために有効磁束が少なくなって、トルクセン
サに高い検出感度を期待でき難いという問題があった。The effective magnetic flux passing through the magnetostrictive members (magnetostrictive sleeves) 52 and 54 is
1. Intermediate sleeve 53 and magnetostrictive material (magnetostrictive sleeve) 5
It depends on the cross-sectional area ratio (effective cross-sectional area) occupied by the magnetostrictive materials 52, 54 with respect to the total cross-sectional area of 2,4. In the non-torsion bar method shown in FIG. 13, the effective magnetic flux is reduced because the sectional area ratio of the shaft 51 is large and the effective sectional areas of the magnetostrictive materials (magnetostrictive sleeves) 52 and 54 are small. There was a problem that it was difficult to expect.
【０００５】また、図１４に示したトーションバー方式
では、磁歪スリーブ５２が外嵌されたくびれ部５１ａで
シャフト５１の断面積比率が小さく磁歪スリーブ５２の
有効断面積を相対的に大きくできるので、有効磁束を増
やすことができる。このため、トーションバー方式を採
用すれば、くびれ部５１ａによる剛性の低下要因と有効
磁束の増加要因との両面から、非トーションバー方式に
比べてトルクセンサの検出感度を高くできる。しかし、
これでも検出感度はまだ十分でなかった。このため、ト
ルクセンサの検出感度のさらなる向上が従来から要望さ
れていた。In the torsion bar system shown in FIG. 14, the constriction portion 51a on which the magnetostrictive sleeve 52 is fitted has a small cross-sectional area ratio of the shaft 51, and the effective cross-sectional area of the magnetostrictive sleeve 52 can be relatively increased. The effective magnetic flux can be increased. For this reason, if the torsion bar system is adopted, the detection sensitivity of the torque sensor can be higher than that of the non-torsion bar system in terms of both the factor of the reduction in rigidity due to the constricted portion 51a and the factor of the increase of the effective magnetic flux. But,
Even with this, the detection sensitivity was not yet sufficient. For this reason, a further improvement in the detection sensitivity of the torque sensor has been conventionally demanded.
【０００６】また、中間スリーブ５３を使用する構造で
は、中間スリーブ５３を磁束が通って磁歪材５４を通る
有効磁束が相対的に減ってしまうため、トルクセンサの
検出感度を低下させるという問題もあった。In the structure using the intermediate sleeve 53, the magnetic flux passes through the intermediate sleeve 53 and the effective magnetic flux passing through the magnetostrictive member 54 is relatively reduced, so that the detection sensitivity of the torque sensor is reduced. Was.
【０００７】また、磁歪材（磁歪スリーブ）５２，５４
はシャフト５１や中間スリーブ５３の外周面に密接に固
定されているため、シャフト５１がトルクによって捻じ
れた際に磁歪材５２，５４に径方向に作用する応力の逃
げ場がなくなり、磁歪材５２，５４が面外圧縮を受けて
径方向に膨らんでたわむように歪むことがあった。磁歪
材５２，５４が面外圧縮を受けると、トルクセンサの検
出信号が非線形性の信号となって検出精度の低下に繋が
るという問題があった。Further, magnetostrictive materials (magnetostrictive sleeves) 52, 54
Is tightly fixed to the outer peripheral surfaces of the shaft 51 and the intermediate sleeve 53, so that when the shaft 51 is twisted by torque, there is no place for stress to act on the magnetostrictive materials 52, 54 in the radial direction. 54 may be distorted so that it expands and flexes in the radial direction due to out-of-plane compression. When the magnetostrictive members 52 and 54 are subjected to out-of-plane compression, there is a problem that the detection signal of the torque sensor becomes a non-linear signal, leading to a decrease in detection accuracy.
【０００８】さらにトーションバー方式では、シャフト
５１にくびれ部５１ａを形成する必要があるため、トル
クセンサを使用するユーザにくびれ部５１ａを形成する
という余分な加工を要求しなければならないという問題
があった。Further, in the torsion bar method, since it is necessary to form the constricted portion 51a on the shaft 51, there is a problem that a user who uses the torque sensor needs to perform an extra process of forming the constricted portion 51a. Was.
【０００９】本発明は上記問題点を解消するためになさ
れたものであって、その第１の目的は磁歪材を通る有効
磁束を増やして検出感度を向上させることができるトル
クセンサを提供することにある。第２の目的は、磁歪材
が面外圧縮を受け難くして検出信号の非線形性を防止
し、トルクセンサの検出精度を高めることにある。第３
の目的は、被検出軸に円筒軸を介して磁歪材を固定した
構造としても、磁歪材を通る有効磁束をさほど減らさず
済ませることにある。第４の目的は、トルクセンサを使
用するユーザに被検出軸にくびれ部などのための余分な
加工を強いることなく、磁歪材の有効磁束を増やしてト
ルクセンサの検出感度を向上させることにある。A first object of the present invention is to provide a torque sensor capable of improving the detection sensitivity by increasing the effective magnetic flux passing through a magnetostrictive material. It is in. A second object is to prevent the magnetostrictive material from being subjected to out-of-plane compression, prevent non-linearity of a detection signal, and increase the detection accuracy of the torque sensor. Third
An object of the present invention is to provide a structure in which a magnetostrictive material is fixed to a shaft to be detected via a cylindrical shaft, so that the effective magnetic flux passing through the magnetostrictive material does not need to be reduced so much. A fourth object is to increase the effective magnetic flux of the magnetostrictive material and improve the detection sensitivity of the torque sensor without forcing a user using the torque sensor to perform extra processing for a constricted portion or the like on the shaft to be detected. .
【００１０】[0010]
【課題を解決するための手段】上記第１の目的を達成す
るために請求項１に記載の発明では、被検出軸の外周面
に固定された磁歪材と、該磁歪材を通る磁束を発生させ
る磁束発生手段と、前記被検出軸に作用するトルクに応
じて前記磁歪材が歪むことによる前記磁束の変化を検出
するための検出手段とを備えたトルクセンサにおいて、
前記磁歪材と前記被検出軸の外周面との間には空隙部が
形成されている。In order to achieve the first object, according to the first aspect of the present invention, a magnetostrictive material fixed to an outer peripheral surface of a detected shaft and a magnetic flux passing through the magnetostrictive material are generated. A magnetic flux generating means for causing, and a torque sensor comprising a detecting means for detecting a change in the magnetic flux due to distortion of the magnetostrictive material according to the torque acting on the detected shaft,
A gap is formed between the magnetostrictive material and the outer peripheral surface of the detected shaft.
【００１１】第２の目的を達成するために請求項２に記
載の発明では、請求項１に記載の発明において、前記磁
歪材の下面が前記空隙部に接している。請求項３に記載
の発明では、請求項１又は請求項２に記載の発明におい
て、前記磁歪材は前記被検出軸に外嵌された円筒軸の外
周面に固定されており、前記空隙部は、前記円筒軸に形
成された貫通穴あるいは凹部によって少なくとも形成さ
れている。According to the second aspect of the present invention, in order to achieve the second object, in the first aspect of the present invention, a lower surface of the magnetostrictive material is in contact with the gap. In the invention described in claim 3, in the invention described in claim 1 or 2, the magnetostrictive material is fixed to an outer peripheral surface of a cylindrical shaft externally fitted to the detected shaft, and the gap portion is , At least by a through hole or a recess formed in the cylindrical shaft.
【００１２】第３の目的を達成するために請求項４に記
載の発明では、請求項３に記載の発明において、前記貫
通穴あるいは前記凹部は前記磁気回路を作る磁束を分断
するように前記円筒軸に形成されている。According to a fourth aspect of the present invention, in order to achieve a third object, in the third aspect of the present invention, the through-hole or the concave portion is provided so as to cut off the magnetic flux forming the magnetic circuit. The shaft is formed.
【００１３】第４の目的を達成するために請求項５に記
載の発明では、請求項１〜請求項４のいずれか一項に記
載の発明において、前記被検出軸は前記磁歪材が固定さ
れる領域で同一径を有する。According to a fifth aspect of the present invention, in order to achieve a fourth object, in the invention according to any one of the first to fourth aspects, the detected shaft has the magnetostrictive material fixed thereto. Regions have the same diameter.
【００１４】請求項６に記載の発明では、請求項１〜請
求項４のいずれか一項に記載の発明において、前記被検
出軸には前記磁歪材が固定される領域にくびれ部が形成
されており、前記磁歪材が前記くびれ部を跨るように設
けられることにより前記空隙部の一部が形成されてい
る。According to a sixth aspect of the present invention, in the first aspect of the present invention, a narrow portion is formed on the detected shaft in a region where the magnetostrictive material is fixed. The magnetostrictive member is provided so as to straddle the constricted portion, thereby forming a part of the gap.
【００１５】（作用）従って、請求項１に記載の発明に
よれば、被検出軸に作用するトルクによって磁歪材が歪
むと、磁束発生手段により磁歪材を通るように形成され
た磁束に変化が現れ、この被検出軸に作用したトルクに
応じた磁束の変化が検出手段により検出される。磁歪材
と被検出軸の外周面との間に形成された空隙部によっ
て、被検出軸と磁歪材との総断面積に対する磁歪材の断
面積の占める比率、つまり有効断面積が増加するので、
磁歪材を通る磁束の割合が増えることになる。また、空
隙によって磁歪材が固定された部分で被検出軸の剛性が
小さくなり、被検出軸に作用する単位トルク当たりの磁
歪材の歪み率が相対的に大きくなる。このため、磁束が
通る磁歪材の有効断面積の増加要因と、被検出軸の剛性
低下による磁歪材の歪み率の増加要因とにより、トルク
センサの検出感度が高められる。According to the first aspect of the present invention, when the magnetostrictive material is distorted by the torque acting on the shaft to be detected, the magnetic flux formed by the magnetic flux generating means so as to pass through the magnetostrictive material changes. The detection means detects a change in magnetic flux corresponding to the torque acting on the detected shaft. By the gap formed between the magnetostrictive material and the outer peripheral surface of the detected shaft, the ratio of the cross-sectional area of the magnetostrictive material to the total cross-sectional area of the detected shaft and the magnetostrictive material, that is, the effective cross-sectional area increases.
The proportion of magnetic flux passing through the magnetostrictive material will increase. In addition, the rigidity of the detected shaft is reduced in the portion where the magnetostrictive material is fixed by the gap, and the distortion rate of the magnetostrictive material per unit torque acting on the detected shaft is relatively increased. For this reason, the detection sensitivity of the torque sensor is increased by the factor of increasing the effective area of the magnetostrictive material through which the magnetic flux passes and the factor of increasing the strain rate of the magnetostrictive material due to the decrease in the rigidity of the shaft to be detected.
【００１６】請求項２に記載の発明によれば、被検出軸
にトルクが作用したときに磁歪材に被検出軸の径方向の
応力が働いても、その応力は磁歪材が下面で接した空隙
部で緩和されるので、磁歪材に面外圧縮が作用し難くな
る。According to the second aspect of the present invention, even if a stress in the radial direction of the detected shaft acts on the magnetostrictive material when a torque acts on the detected shaft, the stress is such that the magnetostrictive material contacts the lower surface. Since the magnetostrictive material is relaxed in the gap, out-of-plane compression hardly acts on the magnetostrictive material.
【００１７】請求項３に記載の発明によれば、被検出軸
に外嵌された円筒軸に形成された貫通穴あるいは凹部に
より空隙部の一部が少なくとも形成される。このため、
空隙部により、磁歪材の有効断面積が増えるとともに被
検出軸の剛性が低下して磁歪材の歪み率が大きくなる。
また、磁歪材の下面が空隙部に接するので、磁歪材に面
外圧縮が作用し難くなる。According to the third aspect of the present invention, at least a part of the gap is formed by the through hole or the concave portion formed in the cylindrical shaft externally fitted to the detected shaft. For this reason,
The void increases the effective sectional area of the magnetostrictive material, decreases the rigidity of the detected shaft, and increases the strain rate of the magnetostrictive material.
In addition, since the lower surface of the magnetostrictive material is in contact with the gap, out-of-plane compression hardly acts on the magnetostrictive material.
【００１８】請求項４に記載の発明によれば、円筒軸に
設けられた貫通穴あるいは凹部によってできた空隙部が
磁気回路を作っている磁束を分断するように形成される
ため、円筒軸の磁気抵抗が大きくなって円筒軸に磁束が
通り難くなる。このため、円筒軸を介して磁歪材を設け
ても有効磁束を多く確保し易くなる。According to the fourth aspect of the present invention, the gap formed by the through-hole or the recess provided in the cylindrical shaft is formed so as to separate the magnetic flux forming the magnetic circuit. The magnetic resistance becomes large and it becomes difficult for the magnetic flux to pass through the cylindrical shaft. For this reason, even if the magnetostrictive material is provided via the cylindrical shaft, it is easy to secure a large effective magnetic flux.
【００１９】請求項５に記載の発明によれば、被検出軸
が磁歪材が固定される領域で同一径を有するので、被検
出軸にくびれ部などの加工をしなくてよい。請求項６に
記載の発明によれば、磁歪材が被検出軸に形成されたく
びれ部に跨るように設けられることにより、空隙部の一
部が形成される。According to the fifth aspect of the present invention, since the detected shaft has the same diameter in the region where the magnetostrictive material is fixed, it is not necessary to process the constricted portion on the detected shaft. According to the sixth aspect of the present invention, a part of the gap is formed by providing the magnetostrictive material so as to straddle the constricted portion formed on the shaft to be detected.
【００２０】[0020]
（第１実施形態）以下、本発明を具体化した第１実施形
態を図１〜図４に従って説明する。(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
【００２１】図４はトルクセンサ１が組付けられた部分
における断面図である。被検出軸としてのシャフト２
は、略円筒状のハウジング３の内部に捜通された状態で
ベアリング４を介して回転可能に支持されている。トル
クセンサ１はシャフト２に外嵌された磁歪特性を有する
被検出部５と、被検出部５の歪みによる磁気的変化を検
出するための検出部６とから構成される。FIG. 4 is a sectional view of a portion where the torque sensor 1 is mounted. Shaft 2 as shaft to be detected
Are rotatably supported via bearings 4 in a state where they are located inside a substantially cylindrical housing 3. The torque sensor 1 includes a detected part 5 having a magnetostrictive characteristic fitted to the shaft 2 and a detecting part 6 for detecting a magnetic change due to the distortion of the detected part 5.
【００２２】被検出部５は、図３，図４に示すように、
シャフト２に外嵌された円筒軸としての中間スリーブ７
と、さらに中間スリーブ７に外嵌された円筒状の磁歪材
８とからなる。磁歪材８は中間スリーブ７を介してシャ
フト２に対して一体回転可能に溶接されている。磁歪材
８は磁気歪み効果を有するものであって、パーマロイ、
鉄・ニッケル・クロム合金、Ｎｉ SpanＣ等の高透磁率
軟磁性材料が使用される。磁歪材８の表面（磁歪膜領
域）は、多数の切欠溝８ａが軸心方向に４５と−４５°
をなして周方向に等間隔に形成されたＡ領域とＢ領域
（図３参照）との２つの被検出領域に分けられている。
なお、磁歪材８には、鉄−アルミニウム系の磁歪材料、
モルファス磁歪材料を使用することもできる。The detected part 5 is, as shown in FIGS.
Intermediate sleeve 7 as a cylindrical shaft externally fitted to shaft 2
And a cylindrical magnetostrictive material 8 which is fitted over the intermediate sleeve 7. The magnetostrictive material 8 is welded to the shaft 2 via the intermediate sleeve 7 so as to be integrally rotatable. The magnetostrictive material 8 has a magnetostrictive effect, and is made of permalloy,
A high magnetic permeability soft magnetic material such as an iron / nickel / chromium alloy or Ni SpanC is used. The surface (magnetostrictive film region) of the magnetostrictive material 8 has a large number of notches 8a formed by 45 ° and −45 ° in the axial direction.
Thus, the detection area is divided into two detection areas: an area A and an area B (see FIG. 3) formed at equal intervals in the circumferential direction.
The magnetostrictive material 8 includes an iron-aluminum-based magnetostrictive material,
A morphous magnetostrictive material can also be used.
【００２３】検出部６は、図４に示すようにシャフト２
に対して２つのベアリング（ラジアルベアリング）９を
介して両端にて支持されて相対回転可能に配置された略
円筒状のヨーク１０を備える。ヨーク１０の内周面には
磁歪材８の２つの被検出領域にそれぞれ対向する位置に
２つの凹部が形成され、各凹部には内側に励磁用コイル
１１が、外側に検出用コイル１２がそれぞれ巻回された
ボビン（図示せず）がそれぞれ収納されている。このた
め、軸方向二箇所に位置する各コイル１１，１２は磁歪
材８の表面上の２つの被検出領域に対向して配置されて
いる。ヨーク１０がベアリング９を介してシャフト２に
支持されていることから、ヨーク１０の内周面と磁歪材
８の外周面とのギャップがシャフト２がハウジングに対
して偏心運動をしても必要なほぼ一定に保たれるように
なっている。なお、励磁用コイル１１が磁束発生手段を
構成し、検出用コイル１２が検出手段を構成している。As shown in FIG. 4, the detection unit 6
And a substantially cylindrical yoke 10 supported at both ends via two bearings (radial bearings) 9 and arranged to be relatively rotatable. Two concave portions are formed on the inner peripheral surface of the yoke 10 at positions opposed to the two detection regions of the magnetostrictive material 8, respectively. An exciting coil 11 is provided inside each of the concave portions, and a detecting coil 12 is provided outside each of the concave portions. Each of the wound bobbins (not shown) is stored. For this reason, each of the coils 11 and 12 located at two positions in the axial direction is arranged to face two detection areas on the surface of the magnetostrictive material 8. Since the yoke 10 is supported by the shaft 2 via the bearing 9, a gap between the inner peripheral surface of the yoke 10 and the outer peripheral surface of the magnetostrictive member 8 is required even if the shaft 2 eccentrically moves with respect to the housing. It is kept almost constant. Note that the exciting coil 11 constitutes a magnetic flux generating means, and the detecting coil 12 constitutes a detecting means.
【００２４】励磁用コイル１１は交流電源１３に接続さ
れ、検出用コイル１２は公知の処理回路１４に接続され
ている。処理回路１４は、励磁用コイル１１に所定周波
数（Ｈｚ）の交流電流を流す制御を行う。励磁用コイル
１１に交流電流が流れることにより、ヨーク１０→磁歪
材８→ヨーク１０を磁束が通る２つの磁気回路が、Ａ領
域とＢ領域のそれぞれに対して形成される。磁歪材８を
通る磁束は、切欠溝８ａにより分断された各領域を切欠
溝８ａに沿うように、磁歪材８の軸線方向に対して４５
°または−４５°の傾き方向をとる。この磁束の変化に
より検出用コイル１２に誘導される誘導起電力が処理回
路１４に出力されるようになっている。The exciting coil 11 is connected to an AC power supply 13, and the detecting coil 12 is connected to a known processing circuit 14. The processing circuit 14 controls to supply an alternating current of a predetermined frequency (Hz) to the exciting coil 11. When an alternating current flows through the exciting coil 11, two magnetic circuits through which the magnetic flux passes through the yoke 10 → the magnetostrictive material 8 → the yoke 10 are formed for each of the A region and the B region. The magnetic flux passing through the magnetostrictive material 8 is applied to the area of the magnetostrictive material 8 along the axial direction of the magnetostrictive material 8 so that each region divided by the notch 8a extends along the notch 8a.
Take a tilt direction of ° or -45 °. The induced electromotive force induced in the detection coil 12 by the change of the magnetic flux is output to the processing circuit 14.
【００２５】２つの検出用コイル１２から出力される各
誘導起電力は、磁歪材８のＡ領域とＢ領域における歪
み、すなわちシャフト２のトルクに比例する。シャフト
２にトルクが作用したとき、その際の回転方向に応じて
Ａ領域とＢ領域には一方に圧縮力が他方に引張力が作用
する。磁歪材８は、引張力が作用すると透磁率が大きく
なり、圧縮力が作用すると透磁率が小さくなる。このた
め、各検出用コイル１１，１２からの誘導起電力は、引
張力が働いた被検出領域を検出する側で大きく、圧縮力
が働いた被検出領域を検出する側で小さくなる。Each induced electromotive force output from the two detecting coils 12 is proportional to the strain in the A region and the B region of the magnetostrictive material 8, that is, the torque of the shaft 2. When a torque acts on the shaft 2, a compressive force acts on one of the areas A and B, and a tensile force acts on the other, according to the rotation direction at that time. The magnetic permeability of the magnetostrictive material 8 increases when a tensile force acts, and decreases when a compressive force acts. For this reason, the induced electromotive force from each of the detection coils 11 and 12 is large on the side that detects the detected area where the tensile force is applied, and is small on the side that detects the detected area where the compressive force is applied.
【００２６】処理回路１４は、両検出用コイル１２から
入力した誘導起電力を差動回路（図示せず）で減算し、
その減算した信号を内部に設けられた整流回路等で整流
して公知の回路でトルクの値を求めるようになってい
る。差動回路で減算するのは、温度変化等による外乱ノ
イズを相殺して補償することで、精度の高いトルク検出
を行うためである。検出用コイル１２からの出力信号
は、シャフト２にトルクがかかっていないときに処理回
路１４が零トルクを検出するようにレベル設定されてい
る。そして、処理回路１４は検出信号の信号レベルが零
レベルに対して正側にどれだけの値をとるか、負側にど
れだけの値をとるかによって、トルクの大きさ及び方向
を検出するようになっている。The processing circuit 14 subtracts the induced electromotive force input from both detection coils 12 by a differential circuit (not shown),
The subtracted signal is rectified by a rectifying circuit or the like provided therein to obtain a torque value by a known circuit. The reason why the subtraction is performed by the differential circuit is to perform highly accurate torque detection by canceling and compensating for disturbance noise due to a temperature change or the like. The level of the output signal from the detection coil 12 is set so that the processing circuit 14 detects zero torque when no torque is applied to the shaft 2. Then, the processing circuit 14 detects the magnitude and direction of the torque based on how much the signal level of the detection signal takes on the positive side with respect to the zero level and how much the value takes on the negative side. It has become.
【００２７】本実施形態では検出部６を構成する中間ス
リーブ７に特徴を有する。図２に示すように、中間スリ
ーブ７には、磁歪材８の同図に鎖線で示す外嵌位置に相
当する軸方向中央部位に、複数の貫通穴としての窓穴７
ａが周方向に沿って等間隔に形成されている。窓穴７ａ
の軸方向幅は、ヨーク１０の軸方向二箇所に位置する各
コイル１１，１２が対向するに十分な長さに設定されて
いる。The present embodiment has a feature in the intermediate sleeve 7 constituting the detecting section 6. As shown in FIG. 2, a plurality of window holes 7 as a plurality of through holes are formed in the intermediate sleeve 7 at an axially central portion corresponding to an outer fitting position of the magnetostrictive material 8 indicated by a chain line in FIG.
a are formed at equal intervals along the circumferential direction. Window hole 7a
Is set to a length sufficient for the coils 11 and 12 located at two axial positions of the yoke 10 to face each other.
【００２８】図１に示すように、磁歪材８を外嵌する中
間スリーブ７がシャフト２に外嵌された状態では、シャ
フト２の外周面と磁歪材８の内周面の間に窓穴７ａによ
る空隙部Ｐが形成されている。なお、中間スリーブ７を
介する構造としたのは、中間スリーブ７の寸法精度を一
定レベル以上に確保しておくことにより、シャフト２の
加工精度をさほど厳しくしなくても、磁歪材８がシャフ
ト２に対して心出しされ、トルクセンサ１の検出精度を
安定させられるようにするためである。よって、中間ス
リーブ７はこの目的を満たし得る寸法精度で加工されて
いる。As shown in FIG. 1, when the intermediate sleeve 7 for externally fitting the magnetostrictive material 8 is externally fitted to the shaft 2, a window hole 7a is formed between the outer peripheral surface of the shaft 2 and the inner peripheral surface of the magnetostrictive material 8. Is formed. The structure with the intermediate sleeve 7 interposed is such that the dimensional accuracy of the intermediate sleeve 7 is maintained at a certain level or more, so that the magnetostrictive material 8 can be mounted on the shaft 2 even if the machining accuracy of the shaft 2 is not so severe. This is to allow the detection accuracy of the torque sensor 1 to be stabilized. Therefore, the intermediate sleeve 7 is machined with dimensional accuracy that can satisfy this purpose.
【００２９】次に、このトルクセンサ１の作用を説明す
る。トルクセンサ１の作動中は、交流電源１３から励磁
用コイル１１に一定の振幅および周波数の交流電流が流
され、磁束がヨーク１０→磁歪材８→ヨーク１０を通る
２つの磁気回路が形成される。シャフト２に回転力が加
えられてトルクが発生すると、磁歪材８を軸方向に分け
るＡ領域とＢ領域は、それぞれ一方が圧縮力を他方が引
張力を受ける。このため、Ａ領域とＢ領域の磁束の変化
を検出する各検出用コイル１２には、引張力を受けた被
検出領域を検出する側で大きな、圧縮力を受けた被検出
領域を検出する側で小さくなるようなシャフト２のトル
クに比例する誘導起電力が発生する。Next, the operation of the torque sensor 1 will be described. During the operation of the torque sensor 1, an AC current having a constant amplitude and frequency is supplied from the AC power supply 13 to the exciting coil 11, and two magnetic circuits are formed in which the magnetic flux passes through the yoke 10, the magnetostrictive material 8, and the yoke 10. . When a torque is generated by applying a rotational force to the shaft 2, one of a region A and a region B that divide the magnetostrictive material 8 in the axial direction receives a compressive force and the other receives a tensile force. For this reason, each of the detection coils 12 for detecting a change in the magnetic flux in the A region and the B region has a large side on the side for detecting the detection region subjected to the tensile force and a side on the side for detecting the detection region subjected to the compression force. , An induced electromotive force proportional to the torque of the shaft 2 is generated.
【００３０】２つの検出用コイル１２に誘導された誘導
起電力は処理回路１４に入力される。処理回路１４は、
各検出用コイル１２から入力電圧を差動回路で減算し、
その減算した信号を内部に設けられた整流回路等で整流
して公知の回路でトルクの値を求める。The induced electromotive force induced by the two detection coils 12 is input to the processing circuit 14. The processing circuit 14
The input voltage is subtracted from each detection coil 12 by a differential circuit,
The subtracted signal is rectified by a rectifying circuit or the like provided therein to obtain a torque value by a known circuit.
【００３１】ところで、２つの磁気回路を形成するよう
に磁歪材８を通る磁束は、切欠溝８ａで分断された間の
領域を４５°あるいは−４５°の方向に斜めに通り、こ
のため磁歪材８における磁束の向きは周方向成分をも
つ。そして、中間スリーブ７には周方向に沿って複数の
窓穴７ａが磁気回路に相当する部位に形成されているた
め、窓穴７ａによってできた空隙部Ｐにより中間スリー
ブ７が磁気的に絶縁され、その磁気抵抗が大きくなる。
このため、中間スリーブ７に磁束が通り難くなり、その
分だけ磁歪材８を通る磁束の割合が増えることになっ
て、トルクの検出感度に寄与する磁歪材８を通る磁束
（有効磁束）が相対的に増加することになる。By the way, the magnetic flux passing through the magnetostrictive member 8 so as to form two magnetic circuits passes obliquely in the direction of 45 ° or −45 ° through the region divided by the cutout groove 8a. 8 has a circumferential component. Further, since a plurality of window holes 7a are formed in the intermediate sleeve 7 along a circumferential direction at a portion corresponding to a magnetic circuit, the intermediate sleeve 7 is magnetically insulated by the gap P formed by the window hole 7a. , Its magnetic resistance increases.
For this reason, it becomes difficult for the magnetic flux to pass through the intermediate sleeve 7, and the proportion of the magnetic flux passing through the magnetostrictive material 8 increases by that much, so that the magnetic flux (effective magnetic flux) passing through the magnetostrictive material 8 that contributes to the torque detection sensitivity is relatively high. Will increase.
【００３２】また、中間スリーブ７に形成された窓穴７
ａによってできた空隙部Ｐにより、磁束が通ることがで
きる金属材部分、すなわちシャフト２，中間スリーブ７
及び磁歪材８の総断面積に対して磁歪材８の断面積が占
める比率（つまり有効断面積）が増えることになる。こ
のため、有効断面積の増加の点からも磁歪材８を通る磁
束の割合が増え、有効磁束が増加することになる。The window hole 7 formed in the intermediate sleeve 7
The metal part through which the magnetic flux can pass, that is, the shaft 2, the intermediate sleeve 7,
In addition, the ratio of the cross-sectional area of the magnetostrictive material 8 to the total cross-sectional area of the magnetostrictive material 8 (that is, the effective cross-sectional area) increases. Therefore, the ratio of the magnetic flux passing through the magnetostrictive material 8 increases from the viewpoint of the increase of the effective cross-sectional area, and the effective magnetic flux increases.
【００３３】さらに中間スリーブ７の剛性は窓穴７ａに
よってできた空隙部Ｐにより相対的に小さくなる。この
ため、シャフト２にトルクが作用したときの磁歪材８の
歪み易さ、すなわち単位トルク当たりの磁歪材８の歪み
率が相対的に大きくなる。従って、磁歪材８の歪み率の
増大によって、単位トルク当たりの有効磁束の変化量が
大きくなる。よって、磁歪材８を通る有効磁束の増加要
因と、有効磁束の単位トルク当たりの変化量の増大要因
とから、トルクセンサ１の検出感度が高くなる。Further, the rigidity of the intermediate sleeve 7 is relatively reduced by the gap P formed by the window hole 7a. Therefore, the distortion of the magnetostrictive material 8 when a torque acts on the shaft 2, that is, the distortion rate of the magnetostrictive material 8 per unit torque becomes relatively large. Therefore, the amount of change in the effective magnetic flux per unit torque increases due to the increase in the strain rate of the magnetostrictive material 8. Therefore, the detection sensitivity of the torque sensor 1 is increased due to an increase factor of the effective magnetic flux passing through the magnetostrictive member 8 and an increase factor of a change amount of the effective magnetic flux per unit torque.
【００３４】また、シャフト２にトルクが作用した際に
磁歪材８の径方向にかかる応力は、窓穴７ａによる空隙
部Ｐで緩和される。このため、磁歪材８に面外圧縮が働
き難くなる。この結果、トルクセンサ１の検出信号が非
線形性を有するようになる不具合が防止される。The stress applied to the magnetostrictive member 8 in the radial direction when a torque acts on the shaft 2 is relieved by the gap P formed by the window hole 7a. For this reason, the out-of-plane compression hardly acts on the magnetostrictive material 8. As a result, a problem that the detection signal of the torque sensor 1 becomes non-linear is prevented.
【００３５】また、本実施形態では、ヨーク１０がシャ
フト２に対してベアリング９を介して回動可能に支持さ
れた構造であるため、シャフト２がハウジング３内を偏
心して回転するようなことがあっても、ヨーク１０と磁
歪材８とのギャップがほぼ一定に保たれる。In this embodiment, since the yoke 10 is rotatably supported on the shaft 2 via the bearing 9, the shaft 2 may be eccentrically rotated in the housing 3. Even if there is, the gap between the yoke 10 and the magnetostrictive material 8 is kept almost constant.
【００３６】例えばヨークをハウジングに固定する従来
知られた構造では、シャフトの偏心運動によりヨークと
磁歪材とのギャップが変動して検出精度が低下する恐れ
があるため、これを回避するためシャフトのハウジング
に対する心出しに厳しい条件が要求される。また、シャ
フトをハウジングに対して偏心しないように組付けて
も、ハウジングの加工精度によってはその内周面に固定
したヨークに位置のばらつきが発生して、ヨークと磁歪
材とのギャップが変動することも起こり得るため、ハウ
ジングの加工精度を厳しくしたり、ベアリング４をヨー
クの近くに配置するなどの対策が必要になる。そして、
これらの対策は、トルクセンサ１のユーザ側で打たなけ
ればならなかった。しかし、本実施形態によれば、ヨー
ク１０がシャフト２に相対回転する構造であって、ギャ
ップがほぼ一定に保たれるため、ハウジング３の加工精
度をユーザに厳しく要求しなくて済み、ベアリング４も
ユーザが所望する位置に自由に配置することができる。For example, in a conventionally known structure in which the yoke is fixed to the housing, the gap between the yoke and the magnetostrictive material may fluctuate due to the eccentric movement of the shaft, which may lower the detection accuracy. Strict conditions are required for centering the housing. Further, even if the shaft is mounted so as not to be eccentric with respect to the housing, the position of the yoke fixed to the inner peripheral surface thereof varies depending on the processing accuracy of the housing, and the gap between the yoke and the magnetostrictive material fluctuates. Therefore, it is necessary to take measures such as strict processing accuracy of the housing and arranging the bearing 4 near the yoke. And
These measures have to be taken by the user of the torque sensor 1. However, according to the present embodiment, since the yoke 10 is configured to rotate relative to the shaft 2 and the gap is kept substantially constant, the processing accuracy of the housing 3 does not need to be strictly required by the user, and the bearing 4 is not required. Can be freely arranged at a position desired by the user.
【００３７】以上詳述したようにこの実施形態によれ
ば、次の効果が得られる。 （１）中間スリーブ７にその周方向に複数の窓穴７ａを
設け、磁歪材８の内周面とシャフト２の外周面との間に
空隙部Ｐを設けたので、磁歪材８の有効断面積を大きく
して磁歪材８を通る有効磁束を多くすることができる。
また、中間スリーブ７を周方向に通ろうとする磁束が窓
穴７ａによる空隙部Ｐに遮断され、中間スリーブ７の磁
気抵抗が大きくなって磁束が通り難くなるので、この点
からも磁歪材８を通る有効磁束を多くすることができ
る。さらに、窓穴７ａの形成により中間スリーブ７の剛
性が低減するので、シャフト２に作用するトルクによる
磁歪材８の歪み率を大きくでき、トルク変化に対する検
出用コイル１２の誘導起電力の変化割合を大きくするこ
とができる。よって、これらの３つの効果により、検出
用コイル１２から出力される信号のＳ／Ｎ比を向上さ
せ、トルクセンサ１の検出感度を向上させることができ
る。As described in detail above, according to this embodiment, the following effects can be obtained. (1) Since a plurality of window holes 7a are provided in the intermediate sleeve 7 in the circumferential direction, and a gap P is provided between the inner circumferential surface of the magnetostrictive material 8 and the outer circumferential surface of the shaft 2, the effective cutting of the magnetostrictive material 8 is enabled. The effective magnetic flux passing through the magnetostrictive member 8 can be increased by increasing the area.
In addition, the magnetic flux that is going to pass through the intermediate sleeve 7 in the circumferential direction is blocked by the gap P by the window hole 7a, and the magnetic resistance of the intermediate sleeve 7 becomes large, making it difficult for the magnetic flux to pass. The effective magnetic flux that passes can be increased. Further, since the rigidity of the intermediate sleeve 7 is reduced by forming the window hole 7a, the distortion rate of the magnetostrictive material 8 due to the torque acting on the shaft 2 can be increased, and the rate of change of the induced electromotive force of the detection coil 12 with respect to the torque change can be reduced. Can be bigger. Therefore, by these three effects, the S / N ratio of the signal output from the detection coil 12 can be improved, and the detection sensitivity of the torque sensor 1 can be improved.
【００３８】（２）シャフト２にトルクが作用した際に
磁歪材８に働く径方向の応力が窓穴７ａによる空隙部Ｐ
で緩和され、磁歪材８が面外圧縮を受け難くなるので、
トルクセン１サの検出信号の非線形性を防止することが
できる。(2) The radial stress acting on the magnetostrictive material 8 when a torque acts on the shaft 2 is reduced by the void P due to the window hole 7a.
And the magnetostrictive material 8 is less susceptible to out-of-plane compression.
Non-linearity of the detection signal of the torque sensor can be prevented.
【００３９】（３）トルクセンサ１は円柱状のシャフト
２に組付けられるので、ユーザにくびれ部の形成などの
余分な加工を要求しなくても、トルクセンサ１の検出精
度を高く確保することができる。(3) Since the torque sensor 1 is mounted on the cylindrical shaft 2, the detection accuracy of the torque sensor 1 can be kept high without requiring the user to perform extra processing such as formation of a constricted portion. Can be.
【００４０】（４）ヨーク１０をシャフト２に対してベ
アリング９を介して相対回転可能に支持したので、シャ
フト２に外嵌された磁歪材８とヨーク１０との間のギャ
ップをシャフト２の偏心やハウジング３の加工精度によ
らず、常にほぼ一定に保つことができ、トルクセンサ１
の検出精度を高く確保できる。また、ギャップを一定に
保てることから、トルクセンサ１のユーザに対してハウ
ジング３の加工精度を厳しく要求しなくて済み、またベ
アリング４の位置をユーザが自由に設定することができ
る。(4) Since the yoke 10 is supported so as to be rotatable relative to the shaft 2 via the bearing 9, the gap between the magnetostrictive material 8 externally fitted on the shaft 2 and the yoke 10 is set to the eccentricity of the shaft 2. Irrespective of the machining accuracy of the housing 3 and the housing 3, the torque sensor 1
High detection accuracy can be secured. In addition, since the gap can be kept constant, there is no need to strictly demand the machining accuracy of the housing 3 for the user of the torque sensor 1, and the position of the bearing 4 can be set freely by the user.
【００４１】（第２実施形態）次に本発明を具体化した
第２実施形態を説明する。この実施形態は、第１実施形
態で使用した中間スリーブ７をより広い空隙部Ｐが確保
されるような形状にしたものである。(Second Embodiment) Next, a second embodiment of the present invention will be described. In this embodiment, the intermediate sleeve 7 used in the first embodiment is shaped so that a wider gap P is secured.
【００４２】図５に示すように、中間スリーブ７の外周
面中央部には周方向に亘る凹部（くびれ部）７ｂが形成
されている。そして、凹部７ｂの底面に複数の窓穴７ａ
が周方向に等間隔に形成されている。As shown in FIG. 5, a concave portion (bent portion) 7b extending in the circumferential direction is formed at the center of the outer peripheral surface of the intermediate sleeve 7. Then, a plurality of window holes 7a are formed in the bottom surface of the concave portion 7b.
Are formed at equal intervals in the circumferential direction.
【００４３】図６に示すように、シャフト２に外嵌され
た中間スリーブ７には、その軸方向中央位置に円筒状の
磁歪材８が外嵌されている。磁歪材８は凹部７ｂを跨ぐ
ように配置されている。このため、窓穴７ａによってで
きた空隙部Ｐ１と、凹部７ｂによってできた空隙部Ｐ２
とにより、第１実施形態の構成に比べてより広い空隙部
Ｐが確保される。よって、トルクセンサ１の検出感度を
決める磁束の通る有効断面積がさらに増え、しかも中間
スリーブ７の剛性がさらに低下して単位トルク当たりの
磁歪材の歪み率もさらに向上する。また、磁歪材８はそ
の軸方向中央部分における内周面全体で凹部７ｂによっ
てできた空隙部Ｐ２に接するので、磁歪材８に径方向に
作用する応力が緩和され易くなる。As shown in FIG. 6, a cylindrical magnetostrictive material 8 is externally fitted to the intermediate sleeve 7 externally fitted to the shaft 2 at the axial center position. The magnetostrictive material 8 is disposed so as to straddle the concave portion 7b. For this reason, a gap P1 formed by the window hole 7a and a gap P2 formed by the recess 7b.
Thereby, a wider gap P is secured than in the configuration of the first embodiment. Therefore, the effective cross-sectional area through which the magnetic flux that determines the detection sensitivity of the torque sensor 1 passes further increases, and the rigidity of the intermediate sleeve 7 further decreases, and the distortion rate of the magnetostrictive material per unit torque further increases. Further, since the magnetostrictive member 8 contacts the void P2 formed by the concave portion 7b on the entire inner peripheral surface at the axial center portion, the stress acting on the magnetostrictive member 8 in the radial direction is easily reduced.
【００４４】よって、この実施形態によれば以下の効果
が得られる。 （１）中間スリーブ７の外周面に複数個の窓穴７ａに加
え、周方向に亘る凹部（くびれ部）７ｂを形成したの
で、磁歪材８とシャフト２との間により広い空隙部Ｐを
確保でき、磁歪材８の有効磁束のさらなる増加、中間ス
リーブ７のさらなる剛性低下を実現できる。従って、第
１実施形態に比べ、トルクセンサ１の検出感度を一層向
上させることができる。Therefore, according to this embodiment, the following effects can be obtained. (1) In addition to the plurality of window holes 7a on the outer peripheral surface of the intermediate sleeve 7, a recess (constriction) 7b extending in the circumferential direction is formed, so that a wider gap P is secured between the magnetostrictive material 8 and the shaft 2. As a result, the effective magnetic flux of the magnetostrictive member 8 can be further increased, and the rigidity of the intermediate sleeve 7 can be further reduced. Therefore, the detection sensitivity of the torque sensor 1 can be further improved as compared with the first embodiment.
【００４５】（２）凹部７ｂによって磁歪材８と中間ス
リ−ブ７との間にできた空隙部Ｐ２に、磁歪材８がその
内周面ほぼ全体（少なくともその軸方向において磁気回
路が形成される領域を含む内周面部位）で接するので、
磁歪材８に径方向に働く応力を空隙部Ｐ２で一層確実に
緩和でき、磁歪材８の面外圧縮による検出信号の非線形
性を一層抑えることができる。(2) In the gap P2 formed between the magnetostrictive material 8 and the intermediate sleeve 7 by the concave portion 7b, the magnetostrictive material 8 is substantially entirely formed on its inner peripheral surface (at least a magnetic circuit is formed in its axial direction). Contact with the inner peripheral area including the region where
The stress acting on the magnetostrictive material 8 in the radial direction can be more reliably alleviated at the gap P2, and the nonlinearity of the detection signal due to the out-of-plane compression of the magnetostrictive material 8 can be further suppressed.
【００４６】その他、第１実施形態において（３）、
（４）で述べた効果が同様に得られる。 （第３実施形態）次に本発明を具体化した第３実施形態
を説明する。In addition, (3) in the first embodiment,
The effect described in (4) is similarly obtained. (Third Embodiment) Next, a third embodiment of the present invention will be described.
【００４７】この実施形態は、第１実施形態におけるシ
ャフト２において中間スリーブ７を嵌合する部位にくび
れ部を形成したものである。図７に示すように、シャフ
ト２はトルクセンサ１を装着する部位で外周径が細く形
成されたくびれ部２ａを有している。中間スリーブ７は
くびれ部２ａに跨がるようにシャフト２に外嵌されてい
る。円筒状の磁歪材８は中間スリーブ７の外周面に窓穴
７ａを塞ぐ状態で外嵌されている。このため、磁歪材８
の内周面側には、窓穴７ａによってできる空隙部Ｐ１と
くびれ部２ａによってできる空隙部Ｐ３とが形成され、
第２実施形態よりかなり広い空隙部Ｐが確保される。In this embodiment, a constricted portion is formed in a portion of the shaft 2 in the first embodiment where the intermediate sleeve 7 is fitted. As shown in FIG. 7, the shaft 2 has a constricted portion 2a having a small outer diameter at a portion where the torque sensor 1 is mounted. The intermediate sleeve 7 is externally fitted to the shaft 2 so as to straddle the constricted portion 2a. The cylindrical magnetostrictive material 8 is fitted on the outer peripheral surface of the intermediate sleeve 7 so as to close the window hole 7a. Therefore, the magnetostrictive material 8
A gap P1 formed by the window hole 7a and a gap P3 formed by the constricted portion 2a are formed on the inner peripheral surface side of
A considerably wider gap P is secured than in the second embodiment.
【００４８】この構成によれば、第２実施形態に比べ、
くびれ部２ａによる空隙Ｐ３が増えて磁歪材８の有効断
面積が増加することから、磁歪材８を通る有効磁束が一
層増えることになる。また、くびれ部２ａによってシャ
フト２の剛性が低下するので、シャフト２に一定トルク
が作用した際の磁歪材８の歪み率がより向上する。よっ
て、トルクセンサ１の検出感度を第２実施形態よりもさ
らに一層高めることができる。また、中間スリーブ７の
径方向の応力が空隙Ｐ３によって緩和されるので、磁歪
材８が中間スリーブ７から径方向に受ける応力が相対的
に小さくなり、磁歪材８の面外圧縮が一層抑えられる。
よって、検出信号の非線形性を一層防止できる。According to this configuration, compared to the second embodiment,
Since the effective area of the magnetostrictive member 8 is increased by increasing the space P3 due to the constricted portion 2a, the effective magnetic flux passing through the magnetostrictive member 8 is further increased. Further, since the rigidity of the shaft 2 is reduced by the constricted portion 2a, the strain rate of the magnetostrictive material 8 when a constant torque acts on the shaft 2 is further improved. Therefore, the detection sensitivity of the torque sensor 1 can be further enhanced as compared with the second embodiment. Further, since the radial stress of the intermediate sleeve 7 is relieved by the gap P3, the stress that the magnetostrictive material 8 receives from the intermediate sleeve 7 in the radial direction becomes relatively small, and the out-of-plane compression of the magnetostrictive material 8 is further suppressed. .
Therefore, the non-linearity of the detection signal can be further prevented.
【００４９】なお、実施形態は上記に限定されず、以下
のようにしてもよい。 （ｎ）図８に示すように、中間スリーブ７のくびれ部７
ｃだけによって空隙部を形成してもよい。磁歪材８はく
びれ部７ｃに跨がるように設けられている。この構成に
よっても、くびれ部７ｃによる空隙部Ｐによって有効磁
束の増加、トルク当たりの磁歪材８の歪み率の増加によ
り、ユーザにシャフト２のくびれ加工を要求することな
く、トルクセンサ１の検出感度を高めることができる。
また磁歪材８が径方向に受ける応力を空隙部Ｐで緩和
し、磁歪材８に面外圧縮がかかり難いので、検出信号の
非線形性を防止できる。The embodiment is not limited to the above, but may be as follows. (N) As shown in FIG.
The void may be formed only by c. The magnetostrictive material 8 is provided so as to straddle the constricted portion 7c. Also according to this configuration, the detection sensitivity of the torque sensor 1 can be reduced without requiring the user to perform the constriction processing of the shaft 2 by increasing the effective magnetic flux and the distortion rate of the magnetostrictive material 8 per torque due to the gap P due to the constriction 7c. Can be increased.
In addition, the stress applied to the magnetostrictive material 8 in the radial direction is reduced by the gap P, and the out-of-plane compression is hardly applied to the magnetostrictive material 8, so that the nonlinearity of the detection signal can be prevented.
【００５０】（ｍ）図９に示すように、磁歪材８を一定
の厚みを保持したまま両端に脚部８ｂをつけ、磁歪材８
をシャフト２の外周面上にブリッジさせた構造としても
よい。磁歪材８の内周面には両端にある２つの脚部８ｂ
によりその間に凹部８ｃが形成される。この構成によっ
ても、ユーザにシャフト２のくびれ加工を要求すること
なく、磁歪材８とシャフト２の間に空隙部Ｐができるの
で、この空隙部Ｐにより、有効磁束の増加、磁歪材８の
剛性低下、磁歪材８の面外圧縮の抑制が図られる。よっ
て、トルクセンサ１の検出感度の向上、及び信号の非線
形性の防止を図ることができる。(M) As shown in FIG. 9, legs 8b are attached to both ends of the magnetostrictive material 8 while maintaining the magnetostrictive material 8 at a constant thickness.
May be bridged on the outer peripheral surface of the shaft 2. Two legs 8b at both ends are provided on the inner peripheral surface of the magnetostrictive material 8.
As a result, a recess 8c is formed therebetween. According to this configuration, a gap P is formed between the magnetostrictive member 8 and the shaft 2 without requiring the user to perform the constriction processing of the shaft 2. Therefore, the gap P increases the effective magnetic flux and the rigidity of the magnetostrictive member 8. Thus, the compression of the magnetostrictive material 8 can be suppressed. Therefore, it is possible to improve the detection sensitivity of the torque sensor 1 and prevent the nonlinearity of the signal.
【００５１】（ｐ）図１０に示すように、中間スリーブ
７の内周面に凹部７ｄを形成することにより、シャフト
２のくびれ部２ａと中間スリーブ７との間にできる空隙
部Ｐをより広く確保できるようにしてもよい。この構成
によれば、磁歪材８を通る有効磁束を増やすことがで
き、しかもシャフト２と中間スリーブ７との両方の剛性
を低下できる。よって、トルクセンサ１の検出感度を高
めることができる。(P) As shown in FIG. 10, by forming a concave portion 7d on the inner peripheral surface of the intermediate sleeve 7, the gap P formed between the constricted portion 2a of the shaft 2 and the intermediate sleeve 7 can be made wider. You may make it secure. According to this configuration, the effective magnetic flux passing through the magnetostrictive member 8 can be increased, and the rigidity of both the shaft 2 and the intermediate sleeve 7 can be reduced. Therefore, the detection sensitivity of the torque sensor 1 can be increased.
【００５２】（ｒ）図１１に示すように、シャフト２の
くびれ部２ａに中間スリーブ７を跨がるように外嵌させ
た構成としてもよい。また、図１２に示すように、磁歪
材料からなる磁歪材としての磁歪スリーブ１５をシャフ
ト２のくびれ部２ａに跨がるように外嵌させた構成とし
てもよい。これらの構成によれば、磁歪材８や磁歪スリ
ーブ１５の有効断面積を増やすことで有効磁束を増やす
とともに、シャフト２の剛性をくびれ部２ａにより小さ
くして磁歪材８や磁歪スリーブ１５の単位トルク当たり
の歪み率を大きくし、トルクセンサ１の検出感度を高め
ることができる。よって、図１１及び図１２の構造を採
用した場合も、従来技術で述べた構造に比べ、トルクセ
ンサ１の検出感度を向上させることができる。(R) As shown in FIG. 11, a configuration may be adopted in which the intermediate sleeve 7 is fitted over the constricted portion 2a of the shaft 2 so as to straddle it. Further, as shown in FIG. 12, a configuration may be adopted in which a magnetostrictive sleeve 15 as a magnetostrictive material made of a magnetostrictive material is externally fitted so as to straddle the constricted portion 2a of the shaft 2. According to these configurations, the effective magnetic flux is increased by increasing the effective cross-sectional area of the magnetostrictive material 8 and the magnetostrictive sleeve 15, and the rigidity of the shaft 2 is reduced by the constricted portion 2 a to reduce the unit torque of the magnetostrictive material 8 and the magnetostrictive sleeve 15. As a result, it is possible to increase the detection rate of the torque sensor 1 by increasing the hit distortion rate. Therefore, even when the structure shown in FIGS. 11 and 12 is employed, the detection sensitivity of the torque sensor 1 can be improved as compared with the structure described in the related art.
【００５３】（ｑ）中間スリーブ７にその周方向に複数
の窓穴７ａを設ける代わりに、軸長の短い２個の中間ス
リーブをシャフト２に外嵌させて凹部を形成し、これら
２個の中間スリーブの外周面に磁歪材８を内周面両端に
て嵌合し、磁歪材８とシャフト２との間に空隙部を形成
してもよい。(Q) Instead of providing a plurality of window holes 7a in the circumferential direction of the intermediate sleeve 7, two intermediate sleeves having a short axial length are fitted on the shaft 2 to form a concave portion, and these two concave portions are formed. The magnetostrictive material 8 may be fitted to the outer peripheral surface of the intermediate sleeve at both ends of the inner peripheral surface to form a gap between the magnetostrictive material 8 and the shaft 2.
【００５４】（ｔ）第２実施形態の中間スリーブ７をシ
ャフト２のくびれ部２ａに外嵌させた構成としてもよ
い。この構成によれば、第２実施形態に比べ、くびれ部
２ａにより空隙部をさらに広く確保でき、有効磁束を一
層増やせる。また、シャフト２の剛性がくびれ部２ａに
よってさらに小さくできる。よって、トルクセンサ１の
検出感度をさらに一層高めることができる。(T) The structure in which the intermediate sleeve 7 of the second embodiment is fitted to the constricted portion 2a of the shaft 2 may be adopted. According to this configuration, as compared with the second embodiment, a wider gap can be secured by the constricted portion 2a, and the effective magnetic flux can be further increased. Further, the rigidity of the shaft 2 can be further reduced by the constricted portion 2a. Therefore, the detection sensitivity of the torque sensor 1 can be further increased.
【００５５】（ｓ）ヨーク１０を支持するためのベアリ
ング９が中間スリーブ７の外周面に外嵌された構造とし
てもよい。この構成によれば、ベアリング９をシャフト
２のスラスト方向にずれないように位置規制するための
規制部を中間スリーブ７に形成しておくことができ、ユ
ーザに対し、ヨーク１０のスラスト方向への位置ずれを
防止する規制部をシャフト２に形成することを要求しな
くて済む。仮に中間スリーブ７がシャフト２に対してス
ラスト方向にずれても、磁歪材８とヨーク１０とが一体
的にスラスト方向にずれて両者の相対位置関係が保たれ
るので、トルクセンサ１の検出精度をさらに向上させる
ことができる。(S) A structure in which a bearing 9 for supporting the yoke 10 is fitted on the outer peripheral surface of the intermediate sleeve 7 may be adopted. According to this configuration, a restricting portion for restricting the position of the bearing 9 so as not to shift in the thrust direction of the shaft 2 can be formed in the intermediate sleeve 7, and the yoke 10 in the thrust direction of the yoke 10 can be provided to the user. There is no need to form a restriction on the shaft 2 for preventing displacement. Even if the intermediate sleeve 7 is displaced in the thrust direction with respect to the shaft 2, the magnetostrictive material 8 and the yoke 10 are displaced in the thrust direction integrally and the relative positional relationship between them is maintained. Can be further improved.
【００５６】（ｋ）磁歪材８をその表面に切欠溝８ａの
ない平滑スリーブとし、平滑スリーブをクロスヘッド型
ピックアップで検出する構成を採用してもよい。前記各
実施形態から把握される請求項に係る発明以外の技術的
思想をその効果とともに以下に記載する。(K) A configuration may be adopted in which the magnetostrictive material 8 is a smooth sleeve having no cutout groove 8a on its surface, and the smooth sleeve is detected by a crosshead type pickup. The technical ideas other than the claimed invention grasped from each of the embodiments are described below together with their effects.
【００５７】（イ）請求項１又は請求項２に記載の発明
において、前記被検出軸に凹部が形成されており、前記
磁歪材が前記凹部を跨ぐように設けられることにより前
記空隙部が形成されている。この構成によれば、被検出
軸に形成された凹部を跨ぐ磁歪材の内側にできた空隙部
によって、有効磁束の増加、被検出軸の剛性の低下が得
られ、トルクセンサの検出感度を向上させることができ
る。(A) In the first or second aspect of the present invention, a concave portion is formed in the detected shaft, and the gap is formed by providing the magnetostrictive material so as to straddle the concave portion. Have been. According to this configuration, the effective magnetic flux is increased, the rigidity of the detected shaft is reduced, and the detection sensitivity of the torque sensor is improved by the void formed inside the magnetostrictive material that straddles the concave portion formed on the detected shaft. Can be done.
【００５８】（ロ）請求項５において、前記磁歪材を通
る磁束の通り道は周方向成分をもち、前記貫通穴は前記
円筒軸にその周方向に沿って複数形成されている。この
構成によれば、周方向に通ろうとする磁束は円筒軸の貫
通穴によって絶縁され、円筒軸に磁束が通り難くなる。
よって、請求項５と同様の効果が得られる。(B) In claim 5, the passage of the magnetic flux passing through the magnetostrictive material has a circumferential component, and a plurality of the through holes are formed in the cylindrical shaft along the circumferential direction. According to this configuration, the magnetic flux that is going to pass in the circumferential direction is insulated by the through hole of the cylindrical shaft, and it is difficult for the magnetic flux to pass through the cylindrical shaft.
Therefore, the same effect as the fifth aspect can be obtained.
【００５９】（ハ）請求項４又は請求項５において、前
記円筒軸は、前記貫通穴と、その外周面に円筒状の前記
磁歪材が跨って外嵌されるように形成されたくびれ部と
を有する。この構成によれば、貫通穴によって円筒軸の
磁気抵抗の増加が図られ、しかも磁歪材がくびれ部によ
ってできた空隙部に内周面全体で接することができ、磁
歪材が面外圧縮を受け難くできる。(C) In the fourth or fifth aspect, the cylindrical shaft comprises: a through hole; and a constricted portion formed so that the cylindrical magnetostrictive material is fitted over the outer peripheral surface thereof. Having. According to this configuration, the magnetoresistance of the cylindrical shaft is increased by the through hole, and the magnetostrictive material can be in contact with the void formed by the constricted portion on the entire inner peripheral surface, and the magnetostrictive material is subjected to out-of-plane compression. Can be difficult.
【００６０】[0060]
【発明の効果】以上詳述したように請求項１に記載の発
明によれば、磁歪材と被検出軸の外周面との間に空隙部
を形成し、空隙部によって、磁歪材の有効断面積を増加
させて有効磁束を増やすとともに、被検出軸の剛性を小
さくして単位トルク当たりの磁歪材の歪み率を大きくし
たので、トルクセンサの検出感度を高めることができ
る。As described in detail above, according to the first aspect of the present invention, a gap is formed between the magnetostrictive material and the outer peripheral surface of the shaft to be detected, and the gap effectively cuts the magnetostrictive material. Since the area is increased to increase the effective magnetic flux and the rigidity of the shaft to be detected is reduced to increase the distortion rate of the magnetostrictive material per unit torque, the detection sensitivity of the torque sensor can be increased.
【００６１】請求項２に記載の発明によれば、被検出軸
にトルクが作用したときに磁歪材に被検出軸の径方向の
応力が緩和されるように、磁歪材の下面に接するように
空隙部を設けたので、磁歪材に面外応力が作用し難くな
って、検出手段により検出される信号の非線形性を防止
できる。According to the second aspect of the present invention, when the torque is applied to the detected shaft, the magnetostrictive material is brought into contact with the lower surface of the magnetostrictive material so that the stress in the radial direction of the detected shaft is reduced. The provision of the air gap makes it difficult for an out-of-plane stress to act on the magnetostrictive material, thereby preventing the non-linearity of the signal detected by the detecting means.
【００６２】請求項３に記載の発明によれば、被検出軸
に外嵌された円筒軸に設けた貫通穴あるいは凹部によっ
て、少なくとも空隙部の一部が形成されるので、空隙部
により、請求項２に記載の発明と同様にトルクセンサの
検出感度を高めるとともに、検出信号の非線形性を防止
して検出精度を高めることができる。According to the third aspect of the present invention, at least a part of the gap is formed by the through hole or the recess provided in the cylindrical shaft externally fitted to the shaft to be detected. Similarly to the invention described in Item 2, the detection sensitivity of the torque sensor can be increased, and the detection accuracy can be improved by preventing the non-linearity of the detection signal.
【００６３】請求項４に記載の発明によれば、円筒軸に
設けられた貫通穴あるいは凹部によってできた空隙部が
磁束の通り道を分断し、円筒軸の磁気抵抗を大きくする
ので、円筒軸を介して磁歪材を設けても磁歪材を通る有
効磁束をさほど減らさずに済む。According to the fourth aspect of the present invention, the void formed by the through hole or the recess provided in the cylindrical shaft divides the passage of the magnetic flux and increases the magnetic resistance of the cylindrical shaft. Even if the magnetostrictive material is provided through the intermediary, the effective magnetic flux passing through the magnetostrictive material does not need to be reduced so much.
【００６４】請求項５に記載の発明によれば、被検出軸
が磁歪材が固定される領域で同一径を有するので、被検
出軸にくびれ部などの加工をしなくて済む。請求項６に
記載の発明によれば、磁歪材が被検出軸に形成されたく
びれ部に跨るように設けられて空隙部の一部が形成され
るので、空隙部をより広く確保でき、トルクセンサの検
出感度を一層高めることができる。According to the fifth aspect of the present invention, since the detected shaft has the same diameter in the region where the magnetostrictive material is fixed, it is not necessary to process the constricted portion or the like on the detected shaft. According to the invention described in claim 6, the magnetostrictive material is provided so as to straddle the constricted portion formed on the shaft to be detected, and a part of the gap is formed. The detection sensitivity of the sensor can be further increased.
【図１】第１実施形態におけるトルクセンサの部分断面
図。FIG. 1 is a partial cross-sectional view of a torque sensor according to a first embodiment.
【図２】中間スリーブと磁歪材を示す斜視図。FIG. 2 is a perspective view showing an intermediate sleeve and a magnetostrictive material.
【図３】シャフトと中間スリーブ及び磁歪材とを示す斜
視図。FIG. 3 is a perspective view showing a shaft, an intermediate sleeve, and a magnetostrictive material.
【図４】トルクセンサがシャフトに装着された状態を示
す断面図。FIG. 4 is a sectional view showing a state where the torque sensor is mounted on a shaft.
【図５】第２実施形態における中間リングを示す斜視
図。FIG. 5 is a perspective view showing an intermediate ring according to a second embodiment.
【図６】トルクセンサの部分断面図。FIG. 6 is a partial cross-sectional view of the torque sensor.
【図７】第３実施形態におけるトルクセンサの部分断面
図。FIG. 7 is a partial cross-sectional view of a torque sensor according to a third embodiment.
【図８】別例のトルクセンサの部分断面図。FIG. 8 is a partial cross-sectional view of another example of a torque sensor.
【図９】図８と異なる別例のトルクセンサの部分断面
図。FIG. 9 is a partial cross-sectional view of another example of a torque sensor different from FIG. 8;
【図１０】図９と異なる別例のトルクセンサの部分断面
図。FIG. 10 is a partial cross-sectional view of another example of a torque sensor different from FIG. 9;
【図１１】図１０と異なる別例のトルクセンサの部分断
面図。FIG. 11 is a partial cross-sectional view of another example of a torque sensor different from FIG. 10;
【図１２】図１１と異なる別例のトルクセンサの部分断
面図。FIG. 12 is a partial cross-sectional view of another example of a torque sensor different from FIG. 11;
【図１３】従来技術におけるトルクセンサの部分断面
図。FIG. 13 is a partial sectional view of a torque sensor according to the related art.
【図１４】同じくトルクセンサの部分断面図。FIG. 14 is a partial sectional view of the torque sensor.
１…トルクセンサ、２…被検出軸を構成するシャフト、
２ａ…くびれ部、７…円筒軸としての中間スリーブ、７
ａ…貫通穴としての窓穴、７ｂ…凹部、７ｃ…凹部とし
てのくびれ部、８…磁歪材、８ｃ…凹部、１１…磁束発
生手段としての励磁用コイル、１２…検出手段としての
検出用コイル、１５…磁歪材としての磁歪スリーブ、Ｐ
…空隙部。1. Torque sensor, 2. Shaft constituting detected shaft,
2a: constricted portion, 7: intermediate sleeve as cylindrical shaft, 7
a: window hole as a through hole, 7b: concave portion, 7c: constricted portion as concave portion, 8: magnetostrictive material, 8c: concave portion, 11: exciting coil as magnetic flux generating means, 12: detecting coil as detecting means , 15 ... Magnetostrictive sleeve as magnetostrictive material, P
... voids.
フロントページの続き (72)発明者 田中 勝章 愛知県刈谷市豊田町２丁目１番地 株式会 社豊田自動織機製作所内Continuation of front page (72) Inventor Katsuaki Tanaka 2-1-1, Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation
Claims (6)
と、該磁歪材を通る磁束を発生させる磁束発生手段と、
前記被検出軸に作用するトルクに応じて前記磁歪材が歪
むことによる前記磁束の変化を検出するための検出手段
とを備えたトルクセンサにおいて、 前記磁歪材と前記被検出軸の外周面との間には空隙部が
形成されているトルクセンサ。1. A magnetostrictive material fixed to an outer peripheral surface of a shaft to be detected, a magnetic flux generating means for generating a magnetic flux passing through the magnetostrictive material,
A torque sensor that detects a change in the magnetic flux due to distortion of the magnetostrictive material in accordance with the torque acting on the detected shaft. A torque sensor having an air gap between them.
いる請求項１に記載のトルクセンサ。2. The torque sensor according to claim 1, wherein a lower surface of the magnetostrictive material is in contact with the gap.
円筒軸の外周面に固定されており、前記空隙部は、前記
円筒軸に形成された貫通穴あるいは凹部によって少なく
とも形成されている請求項１又は請求項２に記載のトル
クセンサ。3. The magnetostrictive material is fixed to an outer peripheral surface of a cylindrical shaft externally fitted to the detected shaft, and the gap is formed at least by a through hole or a concave portion formed in the cylindrical shaft. The torque sensor according to claim 1 or 2, wherein
気回路を作る磁束を分断するように前記円筒軸に形成さ
れている請求項３に記載のトルクセンサ。4. The torque sensor according to claim 3, wherein the through hole or the concave portion is formed on the cylindrical shaft so as to separate a magnetic flux that forms the magnetic circuit.
領域で同一径を有する請求項１〜請求項４のいずれか一
項に記載のトルクセンサ。5. The torque sensor according to claim 1, wherein the detected shaft has the same diameter in a region where the magnetostrictive material is fixed.
る領域にくびれ部が形成されており、前記磁歪材が前記
くびれ部を跨るように設けられることにより前記空隙部
の少なくとも一部が形成されている請求項１〜請求項４
のいずれか一項に記載のトルクセンサ。6. A constricted portion is formed on the detected shaft in a region where the magnetostrictive material is fixed, and the magnetostrictive material is provided so as to straddle the constricted portion, so that at least a part of the gap portion is provided. Is formed.
The torque sensor according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14951897A JPH10339678A (en) | 1997-06-06 | 1997-06-06 | Torque sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14951897A JPH10339678A (en) | 1997-06-06 | 1997-06-06 | Torque sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10339678A true JPH10339678A (en) | 1998-12-22 |
Family
ID=15476897
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14951897A Pending JPH10339678A (en) | 1997-06-06 | 1997-06-06 | Torque sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10339678A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005075950A1 (en) * | 2004-02-04 | 2005-08-18 | Ono Sokki Co.,Ltd. | Torque meter |
| JP2005351750A (en) * | 2004-06-10 | 2005-12-22 | Toyota Motor Corp | Torsional torque sensor for shaft member and manufacturing method therefor |
| EP1249693A3 (en) * | 2001-04-11 | 2006-01-18 | Atsutoshi Goto | Relative-rotational-position detection apparatus |
| JP2007024641A (en) * | 2005-07-14 | 2007-02-01 | Honda Motor Co Ltd | Magnetostrictive torque sensor and formation method of magnetostrictive film thereof |
| JP2008026209A (en) * | 2006-07-24 | 2008-02-07 | Nissan Motor Co Ltd | Magnetostrictive ring and magnetostrictive ring-type torque sensor |
| JP2008026210A (en) * | 2006-07-24 | 2008-02-07 | Nissan Motor Co Ltd | Magnetostrictive ring-type torque sensor |
| JP2013170994A (en) * | 2012-02-22 | 2013-09-02 | Nissan Motor Co Ltd | Magnetostrictive ring type torque sensor, and method of manufacturing magnetostrictive ring type torque sensor |
-
1997
- 1997-06-06 JP JP14951897A patent/JPH10339678A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1249693A3 (en) * | 2001-04-11 | 2006-01-18 | Atsutoshi Goto | Relative-rotational-position detection apparatus |
| WO2005075950A1 (en) * | 2004-02-04 | 2005-08-18 | Ono Sokki Co.,Ltd. | Torque meter |
| US7520182B2 (en) | 2004-02-04 | 2009-04-21 | Ono Sokki Co., Ltd | Torque meter |
| JP2005351750A (en) * | 2004-06-10 | 2005-12-22 | Toyota Motor Corp | Torsional torque sensor for shaft member and manufacturing method therefor |
| JP4527448B2 (en) * | 2004-06-10 | 2010-08-18 | トヨタ自動車株式会社 | Shaft member torsion torque sensor and manufacturing method thereof |
| JP2007024641A (en) * | 2005-07-14 | 2007-02-01 | Honda Motor Co Ltd | Magnetostrictive torque sensor and formation method of magnetostrictive film thereof |
| JP2008026209A (en) * | 2006-07-24 | 2008-02-07 | Nissan Motor Co Ltd | Magnetostrictive ring and magnetostrictive ring-type torque sensor |
| JP2008026210A (en) * | 2006-07-24 | 2008-02-07 | Nissan Motor Co Ltd | Magnetostrictive ring-type torque sensor |
| JP2013170994A (en) * | 2012-02-22 | 2013-09-02 | Nissan Motor Co Ltd | Magnetostrictive ring type torque sensor, and method of manufacturing magnetostrictive ring type torque sensor |
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