JP2001330524A - Torque sensor and detection shaft for torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft for a torque sensor capable of increasing the output of the sensor with an adverse effect of thermal stress reduced even if the length of a magnetostrictive member is reduced in the event that the shaft for the torque sensor is made by joining support parts of another kind of metal to the bulk magnetostrictive member put between them. SOLUTION: The shaft 2 is put through the interior of a substantially cylindrical housing 3 and supported by means of bearings 4 so that it can rotate relative to the housing 3. The shaft 3 is made up of the cylindrical magnetostrictive member 7 forming a detection part 5 and general steel 8 acting as support metallic parts joined/fixed to the member 7 axially put between their two end faces. The steel 8 is formed into a cylindrical shape with its outer diameter formed to be the same as the outer diameter of the member 7. The shaft 2 has circumferentially extending annular grooves 9 formed in the vicinity of joint parts S between the member 7 and the steel 8. The grooves 9 are formed on the member 7 sides.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、被検出軸に作用す
るトルクを磁歪材の透磁率の変化を利用して検出するト
ルクセンサ及びトルクセンサ用被検出軸に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor for detecting a torque acting on a shaft to be detected by utilizing a change in the magnetic permeability of a magnetostrictive material, and a shaft for torque sensor detection.

【０００２】[0002]

【従来の技術】この種のトルクセンサは、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、この透磁率変化に対応
し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。そし
て、磁歪式のトルクセンサ用シャフトの形態としては、
図１１（ａ）に示すように、円柱状の磁歪材５１を円柱
状の支持金属（一般鋼）５２で挟むように接合したも
の、図１１（ｂ）に示すように、一般鋼製のシャフト５
３の外周面に円筒状の磁歪材５４を固着したもの、円筒
状の磁歪材５４を固着する代わりに一般鋼製のシャフト
５３の外周面にメッキ、溶射等で磁歪材層を形成したも
の、あるいはシャフト全体を磁歪材で構成したものがあ
る。しかし、シャフト全体を磁歪材で構成するとコスト
高となるため、図１１（ｂ）に示すようにシャフト５３
の外周面に磁歪材５４を固着した構成や、シャフトの外
周面に磁歪材層を形成した構成が一般に採用される。2. Description of the Related Art A torque sensor of this type is twisted and distorted by a torque acting on a shaft of a magnetostrictive material, and its magnetic permeability changes in accordance with the torque. The torque is detected from the induced electromotive force induced in the coil for use. And, as a form of the shaft for the magnetostrictive torque sensor,
As shown in FIG. 11A, a cylindrical magnetostrictive material 51 is joined so as to be sandwiched by a cylindrical supporting metal (general steel) 52. As shown in FIG. 11B, a general steel shaft is formed. 5
3, a magnetostrictive material layer formed by plating, spraying, etc. on the outer peripheral surface of a shaft 53 made of general steel instead of fixing the cylindrical magnetostrictive material 54 on the outer circumferential surface; Alternatively, there is one in which the entire shaft is made of a magnetostrictive material. However, if the entire shaft is made of a magnetostrictive material, the cost is high. Therefore, as shown in FIG.
The structure in which the magnetostrictive material 54 is fixed to the outer peripheral surface of the shaft or the structure in which the magnetostrictive material layer is formed on the outer peripheral surface of the shaft is generally adopted.

【０００３】シャフトの外周面に磁歪材を固着したトル
クセンサ用シャフトの製造時には磁性焼鈍を実施する
が、これらの構成では異種金属の接合となるため、両者
の膨張係数が異なり、焼鈍処理の冷却過程において応力
が発生し、センサ特性に悪影響を及ぼすため、センサの
出力がシャフト全体を磁歪材で形成したものに比較して
大幅に低下する。特開平５−３２２６７４号公報には、
アモルファス磁性合金薄帯を高温接着したトルク検出装
置において、図１２（ａ）に示すように、センサシャフ
ト５６におけるアモルファス磁性合金薄帯５７の接着部
の両端に応力逃がし溝５８を設け、高温接着後のセンサ
シャフト５６の収縮時にアモルファス磁性合金薄帯５７
の端部を図１２（ｂ），（ｃ）に示すように、応力逃が
し溝５８に逃がし、圧縮応力を減少させてアモルファス
磁性合金の自発磁化を安定化させるものが開示されてい
る。[0003] When manufacturing a torque sensor shaft in which a magnetostrictive material is fixed to the outer peripheral surface of the shaft, magnetic annealing is performed. However, in these configurations, since different types of metals are joined, the expansion coefficients of the two are different, and cooling in the annealing process is performed. Since a stress is generated in the process and adversely affects the sensor characteristics, the output of the sensor is significantly reduced as compared with the case where the entire shaft is formed of a magnetostrictive material. Japanese Patent Application Laid-Open No. Hei 5-322684 discloses that
In the torque detecting device in which the amorphous magnetic alloy ribbon is bonded at a high temperature, stress relief grooves 58 are provided at both ends of the bonded portion of the amorphous magnetic alloy ribbon 57 in the sensor shaft 56 as shown in FIG. When the sensor shaft 56 is contracted, the amorphous magnetic alloy ribbon 57
As shown in FIGS. 12 (b) and 12 (c), an end of the amorphous magnetic alloy is released into a stress relief groove 58 to reduce the compressive stress and stabilize the spontaneous magnetization of the amorphous magnetic alloy.

【０００４】しかし、シャフトの表面に磁歪材を設けた
構成では、軸方向の全体に磁歪材に対する拘束があるた
め、端部に応力逃がし溝５８を設けても、熱応力の影響
が多く残る。これに対して、図１１（ａ）に示す構成の
シャフトでは、磁歪材に対する軸方向の拘束がないた
め、熱応力の影響を受け難い。However, in the configuration in which the magnetostrictive material is provided on the surface of the shaft, since the magnetostrictive material is constrained in the entire axial direction, even if the stress relief groove 58 is provided at the end, much influence of thermal stress remains. On the other hand, in the shaft having the configuration shown in FIG. 11A, there is no axial constraint on the magnetostrictive material, so that the shaft is hardly affected by thermal stress.

【０００５】[0005]

【発明が解決しようとする課題】ところが、図１１
（ａ）に示す構成、即ち円柱状の磁歪材を一般鋼製のシ
ャフトと接合した構成においても、製造コストを低減す
るため磁歪材の長さを短くしていくと、前記熱応力の影
響が大きくなることが判った。図１３に１００℃の温度
差によって磁歪材表面に発生する応力を、磁歪材長を変
えて有限要素法（ＦＥＭ）によって求めたシミュレーシ
ョンの解析結果を示す。なお、試料の直径は３０ｍｍで
ある。However, FIG.
In the configuration shown in (a), that is, in a configuration in which a columnar magnetostrictive material is joined to a general steel shaft, if the length of the magnetostrictive material is reduced to reduce the manufacturing cost, the influence of the thermal stress is reduced. It turned out to be bigger. FIG. 13 shows an analysis result of a simulation in which a stress generated on the surface of the magnetostrictive material due to a temperature difference of 100 ° C. is obtained by a finite element method (FEM) while changing the length of the magnetostrictive material. The diameter of the sample is 30 mm.

【０００６】本発明は前記の問題点に鑑みてなされたも
のであって、その第１の目的はトルクセンサ用シャフト
（被検出軸）をバルクの磁歪材を挟むように他の支持金
属を接合して構成した場合に、磁歪材の長さを短くして
も熱応力による悪影響を少なくでき、センサの出力を高
くすることができるトルクセンサを提供することにあ
る。また、第２の目的はそのトルクセンサ用被検出軸を
提供することにある。The present invention has been made in view of the above problems, and a first object of the present invention is to join a torque sensor shaft (detected shaft) to another supporting metal so as to sandwich a bulk magnetostrictive material. It is an object of the present invention to provide a torque sensor which can reduce adverse effects due to thermal stress even if the length of the magnetostrictive material is shortened and can increase the output of the sensor. A second object is to provide a detected shaft for the torque sensor.

【０００７】[0007]

【課題を解決するための手段】前記第１の目的を達成す
るために請求項１に記載の発明では、被検出軸を、磁歪
材と該磁歪材を軸方向の両端面で挟むように接合固定さ
れた支持金属とで構成し、前記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であっ
て、前記磁歪材の軸方向の両側に接合される支持金属を
筒状とした。In order to achieve the first object, according to the first aspect of the present invention, a shaft to be detected is joined so that the magnetostrictive material is sandwiched between both end surfaces in the axial direction. A magnetic flux generating means configured with a fixed supporting metal and generating a magnetic flux passing through the magnetostrictive material, and for detecting a change in the magnetic flux due to distortion of the magnetostrictive material according to a torque acting on the detected shaft. Wherein the supporting metal joined to both sides of the magnetostrictive member in the axial direction is cylindrical.

【０００８】従って、この発明では、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。磁歪材の軸方向の両側に接合され
る支持金属が筒状のため、磁歪材と支持金属との熱膨張
率の違いに起因した残留熱応力が小さくなる。Therefore, according to the present invention, when the magnetostrictive material is distorted by the torque acting on the detected shaft, the magnetic flux formed by the magnetic flux generating means so as to pass through the magnetostrictive material appears, and the torque acting on the detected shaft is changed. The change of the magnetic flux according to is detected by the detecting means. Since the supporting metal joined to both sides in the axial direction of the magnetostrictive material is cylindrical, the residual thermal stress due to the difference in the coefficient of thermal expansion between the magnetostrictive material and the supporting metal is reduced.

【０００９】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、前記被検出軸は、前記磁歪材と前記
支持金属との接合部付近に周方向に延びる環状の溝が形
成されている。従って、この発明においては、残留熱応
力がより小さくなるとともに、磁歪材の部分におけるト
ルク伝達が均一になり、トルクセンサの出力をより高め
ることができる。According to a second aspect of the present invention, in the first aspect of the invention, the detected shaft has an annular groove extending in a circumferential direction near a joint between the magnetostrictive material and the supporting metal. ing. Therefore, in the present invention, the residual thermal stress is further reduced, and the torque transmission in the magnetostrictive portion is made uniform, so that the output of the torque sensor can be further increased.

【００１０】請求項３に記載の発明では、請求項２に記
載の発明において、前記溝は前記磁歪材側に形成されて
いる。従って、この発明においては、磁歪材の使用長さ
をより短くでき、よりコスト低減に寄与する。According to a third aspect of the present invention, in the second aspect of the present invention, the groove is formed on the magnetostrictive material side. Therefore, in the present invention, the length of use of the magnetostrictive material can be reduced, which contributes to cost reduction.

【００１１】請求項４に記載の発明では、被検出軸を、
磁歪材と該磁歪材を軸方向の両端面で挟むように接合固
定された支持金属とで構成し、前記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で
あって、前記被検出軸の少なくとも前記磁歪材と前記支
持金属との接合部付近の径を磁歪材の前記検出手段と対
向する箇所の径より小さく形成した。In the invention according to claim 4, the detected shaft is
A magnetic flux generating means configured to generate a magnetic flux passing through the magnetostrictive material and a supporting metal that is fixedly joined so as to sandwich the magnetostrictive material between both end surfaces in the axial direction, and a torque acting on the detected shaft. And a detecting means for detecting a change in the magnetic flux due to the distortion of the magnetostrictive material in response to a change in the magnetic flux. Was formed smaller than the diameter of the portion of the magnetostrictive material facing the detection means.

【００１２】従って、この発明においては、請求項１に
記載の発明と同様にして被検出軸に作用するトルクが検
出される。また、磁歪材と支持金属との接合部付近の径
が磁歪材の前記検出手段と対向する箇所の径より小さい
ことにより、磁歪材と支持金属との熱膨張率の違いに起
因した残留熱応力が小さくなる。Therefore, in the present invention, the torque acting on the shaft to be detected is detected in the same manner as in the first aspect of the present invention. Further, since the diameter near the joint between the magnetostrictive material and the supporting metal is smaller than the diameter of the portion of the magnetostrictive material facing the detection means, the residual thermal stress caused by the difference in the coefficient of thermal expansion between the magnetostrictive material and the supporting metal is reduced. Becomes smaller.

【００１３】請求項５に記載の発明では、トルクセンサ
用被検出軸が請求項１〜請求項５のいずれか一項に記載
の被検出軸からなる。従って、この発明の被検出軸を使
用することにより、請求項１〜請求項４のいずれか一項
に記載の発明の作用、効果が得られる。According to a fifth aspect of the present invention, the detected shaft for the torque sensor comprises the detected shaft according to any one of the first to fifth aspects. Therefore, by using the detected shaft of the present invention, the operation and effect of the invention according to any one of claims 1 to 4 can be obtained.

【００１４】[0014]

【発明の実施の形態】以下、本発明を具体化した一実施
の形態を図１〜図６に従って説明する。図２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
出軸としてのトルクセンサ用シャフト（以下、単にシャ
フトと称す）２は、略円筒状のハウジング３の内部に挿
通された状態でベアリング４を介してハウジング３に対
して相対回転可能に支持されている。トルクセンサ１は
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とを備えてい
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a sectional view of a portion where the torque sensor 1 is mounted. A shaft for a torque sensor (hereinafter, simply referred to as a shaft) 2 as a shaft to be detected is rotatably supported by the housing 3 via a bearing 4 while being inserted into a substantially cylindrical housing 3. ing. The torque sensor 1 includes a detected part 5 having a magnetostrictive characteristic and a detecting part 6 for detecting a magnetic change due to the distortion of the detected part 5.

【００１５】図１及び図２に示すように、シャフト２は
被検出部５を構成する円柱状の磁歪材７と、該磁歪材７
を軸方向の両端面で挟むように接合固定された支持金属
としての一般鋼８とで構成されている。一般鋼８は、円
筒状に形成され、その外径が磁歪材７の外径と同じに形
成されている。この実施の形態では磁歪材７と一般鋼８
とは摩擦圧接により接合され、磁歪材７の両端面には一
般鋼８の肉厚と同じ肉厚の環状部７ａが形成され、磁歪
材７は環状部７ａの端面において一般鋼８の端面に接合
されている。シャフト２には磁歪材７と一般鋼８との接
合部Ｓ付近に周方向に延びる環状の溝９が形成されてい
る。この実施の形態では環状の溝９は磁歪材７側に形成
されている。磁歪材７を構成する磁歪材料としては、例
えばパーマロイ、鉄・ニッケル合金、鉄・ニッケル・ク
ロム合金、鉄・アルミニウム系合金等の高透磁率軟磁性
材料が使用される。As shown in FIGS. 1 and 2, the shaft 2 includes a columnar magnetostrictive material 7 constituting the portion 5 to be detected and the magnetostrictive material 7.
And a general steel 8 as a supporting metal joined and fixed so as to be sandwiched between both end surfaces in the axial direction. The general steel 8 is formed in a cylindrical shape, and its outer diameter is formed to be the same as the outer diameter of the magnetostrictive material 7. In this embodiment, magnetostrictive material 7 and general steel 8 are used.
Are joined by friction welding, and an annular portion 7a having the same thickness as that of the general steel 8 is formed on both end surfaces of the magnetostrictive material 7, and the magnetostrictive material 7 is attached to the end surface of the general steel 8 at the end surface of the annular portion 7a. Are joined. An annular groove 9 extending in the circumferential direction is formed near the joint S between the magnetostrictive material 7 and the general steel 8 in the shaft 2. In this embodiment, the annular groove 9 is formed on the magnetostrictive material 7 side. As the magnetostrictive material constituting the magnetostrictive material 7, for example, a high magnetic permeability soft magnetic material such as permalloy, an iron / nickel alloy, an iron / nickel / chromium alloy, or an iron / aluminum alloy is used.

【００１６】磁歪材７の表面（外周面）にはシャフト２
の軸線方向と所定の角度をなす多数の溝７ｂを有する環
状の領域Ａ，Ｂが、軸線と直交する平面に対して対称に
形成されている。多数の溝７ｂは軸心方向に４５度と−
４５度をなすように、周方向に等間隔に形成されてい
る。On the surface (outer peripheral surface) of the magnetostrictive material 7, the shaft 2
Are formed symmetrically with respect to a plane orthogonal to the axis. Many grooves 7b have an angle of 45 degrees in the axial direction.
They are formed at equal intervals in the circumferential direction so as to form 45 degrees.

【００１７】図２に示すように、検出部６はシャフト２
に対して２つのベアリング１０を介して両端にて支持さ
れ、シャフト２に相対回転可能に配置された円筒状のヨ
ーク１１を備えている。ヨーク１１の内周面には前記各
領域Ａ，Ｂと対向する位置にそれぞれ凹部が形成されて
いる。各凹部には内側に励磁用コイル１２が、外側に検
出用コイル１３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。ヨーク１１がベアリン
グ１０を介してシャフト２に支持されているため、シャ
フト２がハウジング３に対して偏心していても、ヨーク
１１と磁歪材７との軸心が一致し易い。なお、励磁用コ
イル１２が磁束発生手段を構成し、検出用コイル１３が
検出手段を構成している。As shown in FIG. 2, the detecting unit 6 includes a shaft 2
And a cylindrical yoke 11 which is supported at both ends via two bearings 10 and is rotatably arranged on the shaft 2. A concave portion is formed on the inner peripheral surface of the yoke 11 at a position facing each of the regions A and B. Each recess accommodates a bobbin (not shown) in which an excitation coil 12 is wound inside and a detection coil 13 is wound outside. Since the yoke 11 is supported by the shaft 2 via the bearing 10, even if the shaft 2 is eccentric with respect to the housing 3, the axes of the yoke 11 and the magnetostrictive material 7 are easily aligned. The exciting coil 12 constitutes a magnetic flux generating means, and the detecting coil 13 constitutes a detecting means.

【００１８】励磁用コイル１２は交流電源１４に接続さ
れ、励磁用コイル１２には所定周波数の交流電流が供給
される。検出用コイル１３は公知の処理回路１５に接続
されている。励磁用コイル１２に交流電流が流れること
により、磁束がヨーク１１→磁歪材７→ヨーク１１を通
る磁気回路が、各領域Ａ，Ｂのそれぞれに対して形成さ
れる。磁歪材７を通る磁束は、溝７ｂにより分断された
各領域を溝７ｂに沿うように、磁歪材７の軸線方向に対
して４５度又は−４５度傾く。The exciting coil 12 is connected to an AC power supply 14, and an AC current having a predetermined frequency is supplied to the exciting coil 12. The detection coil 13 is connected to a known processing circuit 15. When an alternating current flows through the exciting coil 12, magnetic circuits in which magnetic flux passes through the yoke 11 → the magnetostrictive material 7 → the yoke 11 are formed for each of the regions A and B. The magnetic flux passing through the magnetostrictive member 7 is inclined by 45 degrees or -45 degrees with respect to the axial direction of the magnetostrictive member 7 so that each region divided by the groove 7b is along the groove 7b.

【００１９】処理回路１５は、両検出用コイル１３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１３からの出力信号
は、シャフト２にトルクが加わっていないときに処理回
路１５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１５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 15 subtracts the induced electromotive force input from both detection coils 13 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 13 is set so that the processing circuit 15 detects zero torque when no torque is applied to the shaft 2. The processing circuit 15 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.

【００２０】次に、前記のように構成されたトルクセン
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１４から励磁用コイル１２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１１→磁歪材７
→ヨーク１１を通る２つの磁気回路が形成される。２つ
の検出用コイル１３から出力される各誘導起電力は、磁
歪材７の領域Ａと領域Ｂにおける歪み、即ちシャフト２
のトルクに比例する。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７を軸方向に分ける領域Ａ
と領域Ｂは、それぞれ一方が圧縮力を他方が引張力を受
ける。磁歪材７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、領域Ａと領域Ｂの磁束の変化を検出する各検出用コ
イル１３には、引張力を受けた被検出領域を検出する側
で大きくなり、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 configured as described above will be described. During operation of the torque sensor 1, an alternating current having a constant amplitude and frequency is supplied from the AC power supply 14 to the exciting coil 12, and the magnetic flux is changed from the yoke 11 to the magnetostrictive material 7.
→ Two magnetic circuits passing through the yoke 11 are formed. Each induced electromotive force output from the two detection coils 13 is distorted in the region A and the region B of the magnetostrictive material 7, that is, the shaft 2
Is proportional to the torque of When a torque is generated by applying a rotational force to the shaft 2, a region A where the magnetostrictive material 7 is divided in the axial direction
And the region B, one receives a compressive force and the other receives a tensile force. The magnetic permeability of the magnetostrictive material 7 increases when a tensile force acts, and decreases when a compressive force acts. For this reason, each detection coil 13 for detecting a change in the magnetic flux in the region A and the region B has a larger size on the side that detects the detection target region that has received the tensile force, and detects the detection target region that has received the compressive force. An induced electromotive force proportional to the torque of the shaft 2 that decreases on the side is generated.

【００２１】２つの検出用コイル１３に誘導された誘導
起電力は処理回路１５に入力される。処理回路１５に入
力された両検出用コイル１３からの電圧が差動回路で減
算されるとともに、その減算された信号が内部に設けら
れた整流回路等で整流されて公知の回路でトルクの値が
求められる。The induced electromotive force induced by the two detection coils 13 is input to the processing circuit 15. The voltage from the two detection coils 13 input to the processing circuit 15 is subtracted by a differential circuit, and the subtracted signal is rectified by a rectification circuit or the like provided therein, and the torque value is reduced by a known circuit. Is required.

【００２２】図３に、本発明の構成に対応したシャフト
２において、一般鋼８の肉厚を変更した場合と、比較の
ために一般鋼８を円筒状ではなく中実体とした場合とに
ついて、１００℃の温度差によって磁歪材７の表面に発
生する応力分布を、ＦＥＭ（限界要素法）によるシミュ
レーションで求めた結果を示す。磁歪材７は直径が３０
ｍｍで長さ２５ｍｍ、×印は一般鋼８の内径が２０ｍ
ｍ、＋印は一般鋼８の内径が２５ｍｍの場合を示し、△
印は一般鋼８が中実体の比較例の場合を示す。なお、い
ずれの場合も環状の溝９を形成していない場合の結果で
ある。FIG. 3 shows the case where the thickness of the general steel 8 is changed in the shaft 2 corresponding to the configuration of the present invention, and the case where the general steel 8 is not cylindrical but solid for comparison. The results obtained by simulating the stress distribution generated on the surface of the magnetostrictive material 7 by the temperature difference of 100 ° C. by the FEM (limit element method) are shown. Magnetostrictive material 7 has a diameter of 30
mm and length 25mm, x mark is 20m inside diameter of general steel 8
m and + mark show the case where the inner diameter of general steel 8 is 25 mm,
The mark shows the case where the general steel 8 is a solid comparative example. In each case, the results are obtained when the annular groove 9 is not formed.

【００２３】図３から明らかなように、残留応力は磁歪
材７の中央からの距離が大きくなるほど大きくなり、本
発明の構成要件を備えた場合、即ち一般鋼８が筒状に形
成された場合の方が残留応力が小さくなることが確認さ
れた。また、一般鋼８が筒状に形成された場合、肉厚が
薄い方が残留応力が小さくなることが確認された。ま
た、比較例では磁歪材７の中央からの距離の増加に伴っ
て残留応力が次第に増加するのに対して、一般鋼８が筒
状に形成された場合、磁歪材７の中央近傍にほぼ一定の
残留応力となる部分が存在し、肉厚が薄い方が残留応力
が一定となる部分の範囲が大きくなることが確認され
た。As is apparent from FIG. 3, the residual stress increases as the distance from the center of the magnetostrictive member 7 increases, and the residual stress is satisfied when the constituent elements of the present invention are provided, that is, when the general steel 8 is formed in a cylindrical shape. It was confirmed that the residual stress became smaller. Further, when the general steel 8 was formed in a cylindrical shape, it was confirmed that the thinner the wall thickness, the smaller the residual stress. Further, in the comparative example, the residual stress gradually increases as the distance from the center of the magnetostrictive material 7 increases, whereas when the general steel 8 is formed in a cylindrical shape, the residual stress is substantially constant near the center of the magnetostrictive material 7. It was confirmed that there was a portion where the residual stress was present, and that the thinner the wall thickness, the larger the range of the portion where the residual stress was constant.

【００２４】図４に一般鋼８を筒状に形成するととも
に、磁歪材７と一般鋼８との接合部Ｓ付近の磁歪材７側
に、周方向に延びる環状の溝９が形成された場合と、環
状の溝９が無い場合とについて、１００℃の温度差によ
って磁歪材７の表面に発生する応力分布を、ＦＥＭによ
るシミュレーションで求めた結果を示す。また、図５に
同じシャフト２に対して、１０Ｎ・ｍのトルクを印加し
た場合の磁歪材７の表面に発生する剪断応力分布を、Ｆ
ＥＭによるシミュレーションで求めた結果を示す。FIG. 4 shows a case where the general steel 8 is formed in a cylindrical shape and an annular groove 9 extending in the circumferential direction is formed on the magnetostrictive material 7 side near the joint S between the magnetostrictive material 7 and the general steel 8. The results obtained by simulating the stress distribution generated on the surface of the magnetostrictive material 7 by the temperature difference of 100 ° C. by the FEM for the case where there is no annular groove 9 and the case where there is no annular groove 9 are shown. FIG. 5 shows the distribution of shear stress generated on the surface of the magnetostrictive material 7 when a torque of 10 N · m is applied to the same shaft 2 as F
The result obtained by simulation by EM is shown.

【００２５】＋印は環状の溝９が無い場合を示し、○印
は環状の溝９が有る場合を示す。なお、いずれの場合
も、磁歪材７は直径が３０ｍｍで長さ２５ｍｍ、一般鋼
８の内径は２５ｍｍであり、環状の溝９が無いものは図
３の＋印のものと同じである。また、○印の場合、磁歪
材７の中央からの距離が１０ｍｍ以上の部分のデータが
無いのは、１０ｍｍの箇所に環状の溝９が形成されてい
るためである。The mark + indicates that there is no annular groove 9, and the mark 場合 indicates that there is an annular groove 9. In each case, the magnetostrictive material 7 has a diameter of 30 mm and a length of 25 mm, the inner diameter of the general steel 8 is 25 mm, and those without the annular groove 9 are the same as those of the + mark in FIG. Further, in the case of the mark ○, there is no data for a portion whose distance from the center of the magnetostrictive material 7 is 10 mm or more because the annular groove 9 is formed at a position of 10 mm.

【００２６】図４から明らかなように、磁歪材７と一般
鋼８との接合面近傍に環状の溝９を形成した場合、磁歪
材７の中央からの距離が大きな位置においても残留熱応
力の低減効果があることが確認された。また、図５か
ら、前記環状の溝９を設けることにより、トルク伝達が
均一化されることが判明した。As is apparent from FIG. 4, when the annular groove 9 is formed near the joint surface between the magnetostrictive material 7 and the general steel 8, even if the distance from the center of the magnetostrictive material 7 is large, the residual thermal stress can be reduced. It was confirmed that there was a reduction effect. Further, from FIG. 5, it has been found that the provision of the annular groove 9 makes the torque transmission uniform.

【００２７】図６にシャフト２を磁歪材のみで形成した
場合（バルクシャフト）と、磁歪材７の両端に中実材の
一般鋼８を接合した場合（従来）と、磁歪材７の両端に
筒状の一般鋼８を接合するとともに、所定の位置に環状
の溝９が形成された場合（発明品）とについて、１０Ｎ
・ｍのトルクを加えた場合のセンサ出力の比較を示す。
なお、磁歪材７の長さは４０ｍｍである。FIG. 6 shows a case where the shaft 2 is formed only of the magnetostrictive material (bulk shaft), a case where the solid steel 8 is joined to both ends of the magnetostrictive material 7 (conventional), and a case where both ends of the magnetostrictive material 7 are formed. When the cylindrical general steel 8 is joined and the annular groove 9 is formed at a predetermined position (the invention) (10N)
-The comparison of the sensor output when the torque of m is applied is shown.
Note that the length of the magnetostrictive material 7 is 40 mm.

【００２８】従来品ではシャフトの製造時の磁性焼鈍に
おける冷却過程での残留応力が大きく、センサ特性に悪
影響を与えるため、センサ出力がバルクシャフトの１／
４に低下した。しかし、発明品では前記残留応力が小さ
いため、センサの出力がバルクシャフトとほぼ同等の値
を確保できることが確認された。In the conventional product, the residual stress in the cooling process in the magnetic annealing during the production of the shaft is large, which adversely affects the sensor characteristics.
It dropped to 4. However, in the invention product, it was confirmed that the output of the sensor could secure a value almost equivalent to that of the bulk shaft because the residual stress was small.

【００２９】この実施の形態では以下の効果を有する。 （１） 中実状の磁歪材７を軸方向の両端面で挟むよう
に接合固定された支持金属（一般鋼８）で構成したシャ
フト２において、前記支持金属を筒状としたので、磁歪
材７と支持金属との熱膨張率の違いに起因した残留熱応
力が小さくなる。その結果、磁歪材７の長さを短くして
も熱応力による悪影響を少なくでき、トルクセンサ１の
出力を高くすることができる。This embodiment has the following effects. (1) In the shaft 2 made of a support metal (general steel 8) joined and fixed so that the solid magnetostrictive material 7 is sandwiched between both end surfaces in the axial direction, the support metal is formed in a cylindrical shape. Residual thermal stress due to the difference in the coefficient of thermal expansion between the metal and the supporting metal is reduced. As a result, even if the length of the magnetostrictive material 7 is reduced, adverse effects due to thermal stress can be reduced, and the output of the torque sensor 1 can be increased.

【００３０】（２） シャフト２には、磁歪材７と支持
金属（一般鋼８）との接合部Ｓ付近に周方向に延びる環
状の溝９が形成されているため、残留熱応力がより小さ
くなり、トルクの伝達が均一になり、トルクセンサ１の
出力をより高めることができる。(2) Since the annular groove 9 extending in the circumferential direction is formed near the joint S between the magnetostrictive material 7 and the supporting metal (general steel 8) on the shaft 2, the residual thermal stress is smaller. As a result, the transmission of torque becomes uniform, and the output of the torque sensor 1 can be further increased.

【００３１】（３） 環状の溝９が磁歪材７側に形成さ
れているため、磁歪材７の使用長さをより短くでき、よ
りコスト低減に寄与する。 （４） 磁歪材７と支持金属（一般鋼８）とが摩擦圧接
により接合されているため、溶接やレーザーによる接合
に比較して、接合が簡単にできるとともに信頼性が高く
なる。(3) Since the annular groove 9 is formed on the magnetostrictive member 7 side, the length of use of the magnetostrictive member 7 can be further reduced, which further contributes to cost reduction. (4) Since the magnetostrictive member 7 and the supporting metal (general steel 8) are joined by friction welding, joining can be simplified and reliability can be improved as compared with joining by welding or laser.

【００３２】（５） 磁歪材７の両端部に一般鋼８の肉
厚と同じ肉厚の環状部７ａが形成されているため、磁歪
材７と一般鋼８の接触面積が同じになり、磁歪材７と一
般鋼８の温度の上昇具合がほぼ均一になり、摩擦圧接が
良好に行われてより信頼性が高くなる。(5) Since the annular portions 7a having the same thickness as the thickness of the general steel 8 are formed at both ends of the magnetostrictive material 7, the contact area between the magnetostrictive material 7 and the general steel 8 becomes the same, and the magnetostriction is reduced. The temperature rise of the material 7 and the general steel 8 becomes substantially uniform, and the friction welding is performed well, so that the reliability becomes higher.

【００３３】なお、実施の形態は前記に限定されるもの
ではなく、例えば次のように構成してもよい。 ○ 環状の溝９を省略して、磁歪材７に筒状の一般鋼８
を接合しただけの構成としてもよい。この場合、環状の
溝９を形成した場合に比較してトルク伝達が均一化され
る効果は低いが、中実体の一般鋼８を接合した従来品に
比較して、センサの出力を大きくできる。The embodiment is not limited to the above, and may be configured as follows, for example. O The annular groove 9 is omitted, and the magnetostrictive material 7 is formed into a cylindrical general steel 8.
May be simply joined. In this case, the effect of making the torque transmission uniform is low as compared with the case where the annular groove 9 is formed, but the output of the sensor can be increased as compared with the conventional product in which the solid general steel 8 is joined.

【００３４】○ 図７に示すように、磁歪材７の両側に
中実体の支持金属（一般鋼８）を接合し、磁歪材７と一
般鋼８との接合部Ｓ付近に周方向に延びる環状の溝９を
形成した構成としてもよい。図８に磁歪材７の長さを２
５ｍｍ，３５ｍｍ，５５ｍｍと変更し、１００℃の温度
差によって磁歪材７の表面に発生する応力分布を、ＦＥ
Ｍによるシミュレーションで求めた結果を示す。図８か
ら明らかなように、磁歪材７の長さが２５ｍｍの場合に
磁歪材中央の残留応力は約３．１ＭＰａとなる。従っ
て、図１３に示す環状の溝９のない従来品の場合の磁歪
長２５ｍｍの磁歪材中央の残留応力の値の４．９ＭＰａ
に比較して、残留応力が４割程度低下している。即ち、
磁歪材７と接合する支持金属（一般鋼８）を筒状としな
くても、磁歪材７と一般鋼８との接合部Ｓ付近に周方向
に延びる環状の溝９を形成することにより残留熱応力を
小さくでき、トルクセンサの出力を従来品より高めるこ
とができる。As shown in FIG. 7, a solid support metal (general steel 8) is joined to both sides of the magnetostrictive material 7 and an annular ring extending in the circumferential direction near the joint S between the magnetostrictive material 7 and the general steel 8 The groove 9 may be formed. FIG. 8 shows the length of the magnetostrictive material 7 as 2
5 mm, 35 mm, and 55 mm, and the stress distribution generated on the surface of the magnetostrictive
The result obtained by the simulation using M is shown. As is clear from FIG. 8, when the length of the magnetostrictive material 7 is 25 mm, the residual stress at the center of the magnetostrictive material is about 3.1 MPa. Therefore, the value of the residual stress at the center of the magnetostrictive material having a magnetostrictive length of 25 mm in the case of the conventional product without the annular groove 9 shown in FIG.
, The residual stress is reduced by about 40%. That is,
Even if the supporting metal (general steel 8) joined to the magnetostrictive material 7 does not have a cylindrical shape, an annular groove 9 extending in the circumferential direction is formed near the joint S between the magnetostrictive material 7 and the general steel 8 so that residual heat is generated. The stress can be reduced, and the output of the torque sensor can be increased compared to conventional products.

【００３５】○ 環状の溝９に代えて、図９に示すよう
に、一般鋼８の径を磁歪材７の径より小さくし、磁歪材
７の両端部に環状の凹部７ｃを設け、磁歪材７と一般鋼
８との接合部Ｓ付近から磁歪材７及び一般鋼８の径を小
さく形成した構成としてもよい。図１０に磁歪材７の長
さを２５ｍｍ，３５ｍｍ，５５ｍｍと変更し、１００℃
の温度差によって磁歪材７の表面に発生する応力分布
を、ＦＥＭによるシミュレーションで求めた結果を示
す。図１０から明らかなように、図１３に示す環状の溝
９のない従来品に比較して、磁歪材７の長さが２５ｍｍ
の場合に、残留応力が２割以上低下している。In place of the annular groove 9, as shown in FIG. 9, the diameter of the general steel 8 is made smaller than the diameter of the magnetostrictive material 7, and annular concave portions 7 c are provided at both ends of the magnetostrictive material 7. The configuration may be such that the diameter of the magnetostrictive material 7 and the general steel 8 is reduced from near the joint S between the steel 7 and the general steel 8. The length of the magnetostrictive material 7 was changed to 25 mm, 35 mm, and 55 mm in FIG.
2 shows the results of a distribution of stresses generated on the surface of the magnetostrictive material 7 due to the temperature difference obtained by simulation by FEM. As is clear from FIG. 10, the length of the magnetostrictive material 7 is 25 mm compared to the conventional product without the annular groove 9 shown in FIG.
In the case of (1), the residual stress is reduced by 20% or more.

【００３６】○ 支持金属（一般鋼８）が筒状の場合
も、図９に示すように磁歪材７を両端が小径となる形状
とし、支持金属の外径を磁歪材７の小径部と同じに、即
ち領域Ａ、Ｂと対応する部分の径より小さく形成しても
よい。In the case where the supporting metal (general steel 8) is cylindrical, the magnetostrictive member 7 is formed to have a small diameter at both ends as shown in FIG. 9, and the outer diameter of the supporting metal is the same as the small diameter portion of the magnetostrictive member 7. In other words, it may be formed smaller than the diameter of the portion corresponding to the regions A and B.

【００３７】○ 磁歪材７に接合されてシャフト２を構
成する支持金属は、一般鋼に限らず、磁歪材７との接合
が可能で、機械的強度が確保できるものであれば他の金
属でもよいが、コストの点から一般鋼８が好ましい。The support metal joined to the magnetostrictive material 7 to form the shaft 2 is not limited to general steel, but may be any other metal that can be joined to the magnetostrictive material 7 and has sufficient mechanical strength. Good, but general steel 8 is preferred in terms of cost.

【００３８】○ 磁歪材７と支持金属との接合は摩擦圧
接に限らず、溶接やレーザー等による他の接合方法を採
用してもよい。 ○ 筒状の支持金属に磁歪材７を接合する構成におい
て、磁歪材７の端部に筒状支持金属の肉厚と対応する肉
厚の環状部を形成せずに接合してもよい。The joining between the magnetostrictive member 7 and the supporting metal is not limited to friction welding, and other joining methods such as welding and laser may be adopted. In the configuration in which the magnetostrictive material 7 is joined to the cylindrical support metal, the magnetostrictive material 7 may be joined without forming an annular portion having a thickness corresponding to the thickness of the tubular support metal at the end.

【００３９】○ 磁歪材７の表面に形成された溝７ｂは
必須ではなく、溝７ｂを無くして、クロスヘッド型ピッ
クアップで磁束の変化を検出する構成を採用してもよ
い。 ○ シャフト２の径及び磁歪材７の長さはトルクセンサ
の使用条件に応じて適宜変更してもよい。The groove 7b formed on the surface of the magnetostrictive member 7 is not essential, and a configuration may be adopted in which the groove 7b is eliminated and a change in magnetic flux is detected by a crosshead type pickup. The diameter of the shaft 2 and the length of the magnetostrictive member 7 may be appropriately changed according to the use conditions of the torque sensor.

【００４０】次に、前記各実施の形態から把握できる請
求項記載以外の技術的思想（発明）について、以下にそ
の効果とともに記載する。 （１） 請求項１〜請求項３のいずれか一項に記載の発
明において、前記磁歪材及び前記筒状の支持金属は摩擦
圧接により接合されている。この場合、磁歪材及び支持
金属の接合が簡単にかつ良好に行われ、他の接合方法に
比較して信頼性が高くなる。Next, technical ideas (inventions) other than those described in the claims, which can be understood from the above embodiments, will be described below together with their effects. (1) In the invention according to any one of claims 1 to 3, the magnetostrictive material and the cylindrical support metal are joined by friction welding. In this case, the joining of the magnetostrictive material and the supporting metal is performed easily and favorably, and the reliability is higher than other joining methods.

【００４１】（２） （１）において、磁歪材はその両
端部に、支持金属と同じ肉厚の環状部が形成され、該環
状部の端面において支持金属に接合されている。この場
合、摩擦圧接による接合が良好に行われる。(2) In (1), the magnetostrictive material has an annular portion having the same thickness as the supporting metal at both ends thereof, and is joined to the supporting metal at an end face of the annular portion. In this case, joining by friction welding is performed favorably.

【００４２】[0042]

【発明の効果】以上詳述したように、請求項１〜請求項
５に記載の発明によれば、トルクセンサ用シャフト（被
検出軸）をバルクの磁歪材を挟むように他の支持金属を
接合して構成した場合に、磁歪材の長さを短くしても熱
応力による悪影響を少なくでき、センサの出力を高くす
ることができる。As described in detail above, according to the first to fifth aspects of the present invention, the shaft for the torque sensor (the shaft to be detected) is made of another supporting metal such that the bulk magnetostrictive material is sandwiched therebetween. In the case where the magnetostrictive member is joined, even if the length of the magnetostrictive material is shortened, adverse effects due to thermal stress can be reduced and the output of the sensor can be increased.

【図面の簡単な説明】[Brief description of the drawings]

【図１】 一実施の形態のトルクセンサ用シャフトの模
式部分正面図。FIG. 1 is a schematic partial front view of a torque sensor shaft according to an embodiment.

【図２】 トルクセンサの模式断面図。FIG. 2 is a schematic sectional view of a torque sensor.

【図３】 磁歪材表面に発生する熱応力分布を示すグラ
フ。FIG. 3 is a graph showing a distribution of thermal stress generated on the surface of a magnetostrictive material.

【図４】 磁歪材表面に発生する熱応力分布を示すグラ
フ。FIG. 4 is a graph showing a distribution of thermal stress generated on the surface of a magnetostrictive material.

【図５】 トルク印加によって発生する応力分布を示す
グラフ。FIG. 5 is a graph showing a stress distribution generated by applying a torque.

【図６】 センサ出力の比較を示すグラフ。FIG. 6 is a graph showing comparison of sensor outputs.

【図７】 別の実施の形態のトルクセンサ用シャフトの
模式正面図。FIG. 7 is a schematic front view of a torque sensor shaft according to another embodiment.

【図８】 その磁歪材表面に発生する熱応力分布を示す
グラフ。FIG. 8 is a graph showing a distribution of thermal stress generated on the surface of the magnetostrictive material.

【図９】 別の実施の形態のトルクセンサ用シャフトの
模式正面図。FIG. 9 is a schematic front view of a torque sensor shaft according to another embodiment.

【図１０】 その磁歪材表面に発生する熱応力分布を示
すグラフ。FIG. 10 is a graph showing a distribution of thermal stress generated on the surface of the magnetostrictive material.

【図１１】 （ａ）は従来技術のトルクセンサ用シャフ
トの模式正面図、（ｂ）は別の従来技術のトルクセンサ
用シャフトの模式斜視図。11A is a schematic front view of a conventional torque sensor shaft, and FIG. 11B is a schematic perspective view of another conventional torque sensor shaft.

【図１２】 （ａ）は別の従来技術のシャフトの模式断
面図、（ｂ）は同じく正面図、（ｃ）は（ｂ）の部分拡
大断面図。12A is a schematic sectional view of another conventional shaft, FIG. 12B is a front view thereof, and FIG. 12C is a partially enlarged sectional view of FIG.

【図１３】 磁歪材表面に発生する熱応力分布を示すグ
ラフ。FIG. 13 is a graph showing the distribution of thermal stress generated on the surface of a magnetostrictive material.

【符号の説明】[Explanation of symbols]

１…トルクセンサ、２…被検出軸としての（トルクセン
サ用）シャフト、７…磁歪材、８…支持金属としての一
般鋼、９…環状の溝、１２…磁束発生手段としての励磁
用コイル、１３…検出手段としての検出用コイル、Ｓ…
接合部。DESCRIPTION OF SYMBOLS 1 ... Torque sensor, 2 ... Shaft as a shaft to be detected (for torque sensor), 7 ... Magnetostrictive material, 8 ... General steel as supporting metal, 9 ... Annular groove, 12 ... Exciting coil as magnetic flux generating means, 13 ... Detection coil as detection means, S ...
Joint.

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 被検出軸を、磁歪材と該磁歪材を軸方向
の両端面で挟むように接合固定された支持金属とで構成
し、前記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であって、前記磁歪材の軸
方向の両側に接合される支持金属を筒状としたトルクセ
ンサ。1. A magnetic flux generating means for generating a magnetic flux passing through the magnetostrictive material, wherein the shaft to be detected is constituted by a magnetostrictive material and a supporting metal joined and fixed so as to sandwich the magnetostrictive material at both end surfaces in the axial direction. And 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, wherein the magnetostrictive material is joined to both sides in the axial direction of the magnetostrictive material. A torque sensor having a cylindrical support metal. 【請求項２】 前記被検出軸は、前記磁歪材と前記支持
金属との接合部付近に周方向に延びる環状の溝が形成さ
れている請求項１に記載のトルクセンサ。2. The torque sensor according to claim 1, wherein the detected shaft has an annular groove extending in a circumferential direction near a joint between the magnetostrictive material and the supporting metal. 【請求項３】 前記溝は前記磁歪材側に形成されている
請求項２に記載のトルクセンサ。3. The torque sensor according to claim 2, wherein the groove is formed on the magnetostrictive material side. 【請求項４】 被検出軸を、磁歪材と該磁歪材を軸方向
の両端面で挟むように接合固定された支持金属とで構成
し、前記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であって、 前記被検出軸の少なくとも前記磁歪材と前記支持金属と
の接合部付近の径を磁歪材の前記検出手段と対向する箇
所の径より小さく形成したトルクセンサ。4. A magnetic flux generating means for generating a magnetic flux passing through the magnetostrictive material, wherein the shaft to be detected is composed of a magnetostrictive material and a supporting metal joined and fixed so as to sandwich the magnetostrictive material between both end surfaces in the axial direction. And 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, wherein at least the magnetostrictive material of the detected shaft A torque sensor having a diameter near a joint with the supporting metal formed smaller than a diameter of a portion of the magnetostrictive material facing the detection means. 【請求項５】 請求項１〜請求項４のいずれか一項に記
載された被検出軸からなるトルクセンサ用被検出軸。5. A detected shaft for a torque sensor, comprising the detected shaft according to any one of claims 1 to 4.