JP2007278865A - Magnetostrictive torque detecting apparatus - Google Patents
Magnetostrictive torque detecting apparatus Download PDFInfo
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Abstract
Description
本発明は、磁歪特性を利用して回転軸の軸トルクを非接触で検出する装置に関するもので、特に自動車分野、産業機械分野などに適用するものである。 The present invention relates to an apparatus for detecting the axial torque of a rotating shaft in a non-contact manner using magnetostrictive characteristics, and is particularly applicable to the automobile field, industrial machine field, and the like.
自動車のパワーステアリング機構やエンジン制御機構、動力伝達機構などでは軸トルクを正確に検出する手段が古くから望まれている。検出精度を高めることにより、精密制御や効率向上が可能となるため、これまでに様々な手法が提案されてきた。なかでも回転軸の磁歪特性を利用して非接触で軸トルクを検出する手法は、応答性に優れ、高感度化が比較的容易であり、過負荷耐量も大きいことから、トーションバーのねじれ量からトルク検出を行なう従来手法に代わる方式として注目されている。 In the power steering mechanism, engine control mechanism, power transmission mechanism, and the like of automobiles, means for accurately detecting shaft torque has long been desired. Various techniques have been proposed so far because precise control and efficiency can be improved by increasing detection accuracy. In particular, the non-contact method of detecting shaft torque using the magnetostriction characteristics of the rotating shaft is excellent in responsiveness, is relatively easy to increase sensitivity, and has a large overload capability. Therefore, it is attracting attention as an alternative to the conventional method for detecting torque.
例えば特許文献１では、図１４（ａ）に示す様に、回転軸に傾斜角を有する磁性膜115を固着させて、回転軸外周のソレノイドコイルで励磁・検出を行なう手法が提案されている。ところが、この方式は回転軸に磁性膜を接着する等の追加工を施す必要があり、実用上、その磁性膜の剥離が信頼性の低下を招く。さらに、軸の専用化や大径化が必須となるため、装着性が悪い。 For example, Patent Document 1 proposes a method in which a magnetic film 115 having an inclination angle is fixed to a rotating shaft and excitation / detection is performed by a solenoid coil on the outer periphery of the rotating shaft, as shown in FIG. However, this method requires additional processing such as bonding a magnetic film to the rotating shaft, and in practice, peeling of the magnetic film causes a decrease in reliability. Furthermore, since it is essential to specialize the shaft and increase the diameter, the mounting property is poor.
また特許文献２では、図１４（ｂ）に示す様に、回転軸を無加工とし、ループコイルを一定の傾斜角を保ちながら配置することで特許文献１と同様にトルク検出を行なう手法が提案されている。この方式は軸への追加工が不要であるが、感度を高めるために軸の長手方向へ向かって広い領域を検出する必要があるので、装置の大型化が懸念される。 Further, in Patent Document 2, as shown in FIG. 14B, a method is proposed in which torque is detected in the same manner as Patent Document 1 by disposing the rotating shaft without processing and arranging the loop coil while maintaining a constant inclination angle. Has been. Although this method does not require any additional work on the shaft, it is necessary to detect a wide area in the longitudinal direction of the shaft in order to increase sensitivity, and there is a concern that the size of the apparatus will increase.
さらに特許文献３では、図１４（ｃ）に示す様に、特許文献２の課題を克服すべくコイル部分を大幅にコンパクト化する構造が提案されているが、コイル構造が複雑なため多数巻が困難であり、コイルの巻回数に依存した高感度化は実現し難い。 Further, in Patent Document 3, as shown in FIG. 14 (c), a structure for greatly reducing the coil portion is proposed in order to overcome the problem of Patent Document 2, but since the coil structure is complicated, a large number of windings are required. It is difficult to achieve high sensitivity depending on the number of turns of the coil.
上記３種の構造は、何れもコイルが回転軸に隣接しているため、軸の回転振れや異物混入などの影響を受けてコイルが断線する危険性が高く、それらを防止して構造信頼性を確保するためにコイル部分を樹脂などで覆って補強したり、軸とコイル間の空隙を拡大して感度を犠牲にしたりといった回避策が必要になると思われる。 In the above three types of structures, since the coil is adjacent to the rotating shaft, there is a high risk of the coil being disconnected due to the influence of rotational runout of the shaft or contamination of foreign matter. In order to ensure this, it is considered necessary to take measures such as covering and reinforcing the coil part with a resin or the like, or enlarging the gap between the shaft and the coil to sacrifice the sensitivity.
また特許文献４では、図１４（ｄ）に示す様に、回転軸の外周にＵ字形鉄心を設ける構造が記載されている。この場合、励磁専用及び検出専用の鉄心が必要であり、これらを回転軸の外周に複数並べようとすると、構造が複雑化してコンパクト化が困難となる。さらに複数個の鉄心に対してそれぞれコイルを巻回するため、生産性が悪い。 Patent Document 4 describes a structure in which a U-shaped iron core is provided on the outer periphery of a rotating shaft, as shown in FIG. In this case, iron cores dedicated for excitation and detection are necessary, and if a plurality of these are arranged on the outer periphery of the rotating shaft, the structure becomes complicated and it becomes difficult to make it compact. Further, since the coil is wound around each of the plurality of iron cores, productivity is poor.
本発明は、上述した従来の磁歪式トルク検出装置の信頼性、小型化、高感度化、生産性に関わる課題を解決するためのものである。 The present invention is to solve the problems related to reliability, miniaturization, high sensitivity, and productivity of the above-described conventional magnetostrictive torque detector.
本願第１の発明は、巻線したＣ字形軟磁性体の空隙部を回転軸に対向させて回転軸の透磁率の変化を検出するトルクセンサであって、Ｃ字形軟磁性体はその端部どうしが前記空隙部で対向して最接近し、回転軸の軸方向に対して傾斜していることを特徴とするトルクセンサである。 A first invention of the present application is a torque sensor for detecting a change in permeability of a rotating shaft by causing a gap portion of a wound C-shaped soft magnetic material to face the rotating shaft, and the C-shaped soft magnetic material has an end portion thereof. The torque sensor is characterized in that the gaps face each other at the gap and are closest to each other and are inclined with respect to the axial direction of the rotation shaft.
本発明で回転軸の軸方向に対するＣ字形軟磁性体の傾斜角度は＋３５〜＋５５度であることが好ましい。 In the present invention, the inclination angle of the C-shaped soft magnetic material with respect to the axial direction of the rotation axis is preferably +35 to +55 degrees.
本発明で回転軸の軸方向に対するＣ字形軟磁性体の傾斜角度は−３５〜−５５度であることが好ましい。 In the present invention, the inclination angle of the C-shaped soft magnetic material with respect to the axial direction of the rotating shaft is preferably −35 to −55 degrees.
本願第２の発明は、巻線した一対のＣ字形軟磁性体の空隙部を回転軸に対向させて回転軸の透磁率の変化を検出するトルクセンサであって、Ｃ字形軟磁性体はその端部どうしが前記空隙部で対向して最接近し、回転軸の軸方向に対して＋３５〜＋５５度および−３５〜−５５度それぞれ傾斜していることを特徴とするトルクセンサである。 A second invention of the present application is a torque sensor that detects a change in permeability of a rotating shaft by causing a gap between a pair of wound C-shaped soft magnetic materials to face the rotating shaft. The torque sensors are characterized in that the end portions face each other at the gap portion and are closest to each other, and are inclined at +35 to +55 degrees and −35 to −55 degrees with respect to the axial direction of the rotation axis.
本願第３の発明は、本願第１又は２の発明のトルクセンサを回転軸周方向に等間隔に配置してなることを特徴とするトルクセンサである。 A third invention of the present application is a torque sensor comprising the torque sensors of the first or second invention of the present application arranged at equal intervals in the circumferential direction of the rotation axis.
本願第１乃至３の発明のトルクセンサにおいて、Ｃ字形軟磁性体の回転軸に対向する底面は、回転軸表面の曲面に沿った形状であることが好ましい。 In the torque sensors according to the first to third aspects of the present invention, it is preferable that the bottom surface of the C-shaped soft magnetic body facing the rotation axis has a shape along the curved surface of the rotation axis surface.
本願第１乃至３の発明のトルクセンサにおいて、前記空隙部はＣ字形軟磁性体と回転軸間の空隙に対して1.2〜5倍の大きさであることが好ましい。 In the torque sensors of the first to third inventions of the present application, the gap is preferably 1.2 to 5 times larger than the gap between the C-shaped soft magnetic body and the rotation shaft.
以下に、磁歪検出型の回転軸トルク検出装置の原理とともに、本発明の特長を示す。センサに設けられた励磁コイルへ電流を流すと、コイル周辺には図１（ａ）に示す様な磁束201が発生する。コイルで発生する磁束201は、コイルと直交する面内で右ネジの法則に従って閉ループを形成する。また、コイルの巻き方など磁気回路の工夫によって、複数の閉磁路を形成する場合が多い。なお、軸の回転によってセンサとの相対位置が変化しても、軸に回転トルクが加わって歪が生じない限り透磁率が変化しないため、コイルのインダクタンスにも変化は生じない。 The features of the present invention are described below together with the principle of a magnetostrictive detection type rotating shaft torque detection device. When a current is passed through an exciting coil provided in the sensor, a magnetic flux 201 as shown in FIG. 1A is generated around the coil. The magnetic flux 201 generated by the coil forms a closed loop according to the right-handed screw rule in a plane orthogonal to the coil. In many cases, a plurality of closed magnetic paths are formed by devising a magnetic circuit such as a coil winding method. Even if the relative position of the sensor changes due to the rotation of the shaft, the magnetic permeability does not change unless a rotational torque is applied to the shaft to cause distortion, so that the coil inductance does not change.
図１（ａ）の無負荷状態から、図１（ｂ）の様に軸へ回転トルクを付与すると、軸の長手方向に対して＋４５°と−４５°傾斜する方向に、引張応力（＋σ）と圧縮応力（−σ）とがそれぞれ直交しながら同時に発生する。ここで、正の磁歪を有する磁性材料に引張応力が加わると透磁率が増加し、逆に圧縮応力が加わると透磁率が減少する。 When rotational torque is applied to the shaft as shown in FIG. 1B from the no-load state of FIG. 1A, tensile stress (+ σ) in directions inclined by + 45 ° and −45 ° with respect to the longitudinal direction of the shaft. And compressive stress (−σ) are simultaneously generated while being orthogonal to each other. Here, when a tensile stress is applied to a magnetic material having a positive magnetostriction, the magnetic permeability increases. Conversely, when a compressive stress is applied, the magnetic permeability decreases.
この透磁率の変化量や差分量を検出すれば、トルクの正負や絶対量を推定することができる。例えば、図１に示す様に軸に対して−４５°傾斜する方向に螺旋状の励磁コイルがあると仮定する。コイルで発生する磁束は、右ネジの法則に従って閉磁路を形成するので、コイルとは直交する＋４５°方向の面内における透磁率変化の影響を大きく受ける。ここで、＋４５°方向に引張応力が加わったと仮定すると、無負荷時に比べて磁束が流れ易くなるので、コイルのインダクタンスは無負荷時に比べて増加する。反対に圧縮応力が加わると、インダクタンスは減少する。 If the amount of change in magnetic permeability or the amount of difference is detected, the sign of torque or the absolute amount can be estimated. For example, as shown in FIG. 1, it is assumed that there is a helical excitation coil in a direction inclined by −45 ° with respect to the axis. Since the magnetic flux generated in the coil forms a closed magnetic circuit according to the right-handed screw law, it is greatly affected by the permeability change in the + 45 ° direction perpendicular to the coil. Here, if it is assumed that a tensile stress is applied in the + 45 ° direction, the magnetic flux flows more easily than when there is no load, so that the inductance of the coil increases compared to when there is no load. Conversely, when compressive stress is applied, the inductance decreases.
前記磁気ヘッドによって、そのインダクタンスの変化量からトルクを推定するには、無負荷時と＋４５°または−４５°のどちらか一方向の透磁率変化を検出すれば良いことになる。また、＋４５°と−４５°の両方向の透磁率変化を同時に検出し、その差分量を知ることで、より高精度にトルクを推定することが可能になる。＋４５°と−４５°の両方向の透磁率変化を同時に検出する手段としては、図２と図３に示す様な軟磁性体を図７のように組み合わせることで実現可能となる。 In order to estimate the torque from the amount of change in inductance by the magnetic head, it is only necessary to detect a change in permeability in one direction of either + 45 ° or −45 ° when no load is applied. Further, it is possible to estimate the torque with higher accuracy by simultaneously detecting the change in permeability in both directions of + 45 ° and −45 ° and knowing the difference amount. A means for simultaneously detecting the permeability change in both directions of + 45 ° and −45 ° can be realized by combining soft magnetic materials as shown in FIGS. 2 and 3 as shown in FIG.
磁歪式の回転軸トルク検出装置では、軸に対して＋４５°および、または−４５°傾斜方向の透磁率変化を読み取ることが重要であり、特許文献１ではコイルを軸の回転方向に沿って傾斜角なくソレノイド状に巻回する代わりに、回転軸に±４５°傾斜する方向へ磁性膜を設けることで傾斜方向のみに磁束が流れる様に工夫している。また、特許文献２や特許文献３ではコイルに傾斜角を持たせることで軸トルクを検出可能にしている。 In a magnetostrictive rotating shaft torque detector, it is important to read the change in permeability in the + 45 ° and / or −45 ° tilt directions with respect to the shaft. In Patent Document 1, the coil is tilted along the shaft rotation direction. Instead of winding like a solenoid without corners, a magnetic film is provided in a direction inclined by ± 45 ° on the rotation shaft so that the magnetic flux flows only in the inclined direction. Moreover, in patent document 2 and patent document 3, axial torque can be detected by giving the coil an inclination angle.
特許文献１の構造は、コイルが単純なソレノイド状のために多数巻が容易で、高感度化し易いという大きな特長を有するものの、軸への追加工が必要なことが信頼性や生産性を悪化させていた。 Although the structure of Patent Document 1 has a great feature that a coil is a simple solenoid and a large number of windings are easy and high sensitivity is easily achieved, the reliability and productivity deteriorate due to the need for additional work on the shaft. I was letting.
そこで本方式では回転軸を無加工とし、図４〜８に示すように回転軸３に対して空隙２２を介してＣ字形軟磁性体１,２,６,７,８〜１１,または１２〜１９が周方向に並んだ複数の磁極部を形成し、その軟磁性部が回転軸に対して傾斜角を有するとともに、磁極部へ励磁するためのコイル４または５が単純なソレノイド状であることを構造上の主な特徴としている。 Therefore, in this method, the rotating shaft is not processed, and the C-shaped soft magnetic material 1, 2, 6, 7, 8, 11 or 12 to 12 to the rotating shaft 3 through the gap 22 as shown in FIGS. 19 forms a plurality of magnetic pole portions arranged in the circumferential direction, the soft magnetic portion has an inclination angle with respect to the rotation axis, and the coil 4 or 5 for exciting the magnetic pole portion has a simple solenoid shape. Is the main structural feature.
軸への複雑な加工を不要にすることで、装着性と製造コストを大幅に改善することができる。また特許文献１の様に信頼性を損なうことがない。また、コイルをソレノイド状にできるので、巻回数に依存した高感度化が容易になる。さらに、コイルを回転軸から十分離れた位置に配置できるので、コイルが回転軸と接触し、断線する危険性を回避することができる。そしてさらに、回転軸とＣ字形軟磁性体との空隙を大幅に縮小して、高感度化を図ることも容易になる。 By eliminating the need for complicated machining on the shaft, it is possible to greatly improve the mounting property and the manufacturing cost. Further, unlike Patent Document 1, the reliability is not impaired. Further, since the coil can be formed in a solenoid shape, high sensitivity depending on the number of turns is facilitated. Furthermore, since the coil can be disposed at a position sufficiently away from the rotating shaft, it is possible to avoid a risk that the coil contacts the rotating shaft and is disconnected. Furthermore, it is easy to achieve high sensitivity by greatly reducing the gap between the rotating shaft and the C-shaped soft magnetic material.
磁気ヘッドの構造として、前記Ｃ字形軟磁性体は回転軸の長手方向に対して絶対値で３５〜５５°の傾斜角度を有することが好ましい。なお、軟磁性部の傾斜角度は、回転軸のねじり応力が発生する方向である４５°に揃えるのが最も好ましい。しかし、回転軸と磁気ヘッド間の空隙部によって、磁束の流れる方向が若干変化するため、磁気ヘッドの軟磁性部の傾斜角度が理想値である４５°に対して±１０°の範囲でずれても、検出精度に顕著な差を生じることがない。 As the structure of the magnetic head, it is preferable that the C-shaped soft magnetic material has an inclination angle of 35 to 55 ° in absolute value with respect to the longitudinal direction of the rotating shaft. The inclination angle of the soft magnetic part is most preferably set to 45 °, which is the direction in which the torsional stress of the rotating shaft is generated. However, since the direction of magnetic flux changes slightly due to the gap between the rotating shaft and the magnetic head, the tilt angle of the soft magnetic portion of the magnetic head is shifted within a range of ± 10 ° with respect to the ideal value of 45 °. However, there is no significant difference in detection accuracy.
図６に示すように、隣り合うＣ字形軟磁性体、例えば８と９、９と１０、１０と１１、１１と５の間隔が等間隔かつ複数個を配置することによって、磁歪特性のばらつきがある回転軸であっても、回転軸周方向の透磁率変化の平均値を確実に検出することができる。また回転軸の振れ回りが起きても、安定した信号が得られる。 As shown in FIG. 6, by arranging a plurality of adjacent C-shaped soft magnetic bodies, for example, 8 and 9, 9 and 10, 10 and 11, and 11 and 5 at equal intervals, the variation in magnetostriction characteristics can be reduced. Even for a certain rotating shaft, the average value of the permeability change in the circumferential direction of the rotating shaft can be reliably detected. In addition, a stable signal can be obtained even if the rotation of the rotating shaft occurs.
図２、３に示すように、Ｃ字形軟磁性体を回転軸に前記傾斜角度で装着した場合、Ｃ字形軟磁性体の底面は対向する回転軸表面の曲面に沿った形状が好ましい。この場合、底面が平面であるときよりも、回転軸に対する軟磁性部底面の面積が大きくなることから、信号を検出できる範囲が広くなり、透磁率変化を精確に検出することが可能となる。よってセンサ感度が高くなる。本発明の場合、実施例として外径φ18mm、空隙２２は1mmとしているので、この曲面はR10となる。また対向するＣ字形軟磁性体先端同士の空隙２１は近づいていた方が好ましい。この場合も、回転軸に対する軟磁性部底面の面積を大きくすることができるので、透磁率変化を精確に検出することが可能となる。ただし、空隙２１は回転軸とＣ字形軟磁性体間の空隙２２よりも大きい必要がある。仮に空隙２１を空隙２２よりも小さくした場合、軟磁性部先端から流れ出た磁束２０は回転軸表面よりも空隙２１を通り、対向する軟磁性部先端に流れ込む方が優勢となり、センサ感度を低下させる。しかし、空隙２１があまり大き過ぎると回転軸に対向する軟磁性部底面の面積が小さくなることからセンサ感度が低下するため好ましくない。空隙２１は空隙２２の1.2〜5倍の大きさであることが好ましい。 As shown in FIGS. 2 and 3, when the C-shaped soft magnetic body is mounted on the rotating shaft at the inclination angle, the bottom surface of the C-shaped soft magnetic body preferably has a shape along the curved surface of the opposing rotating shaft surface. In this case, since the area of the bottom surface of the soft magnetic part with respect to the rotation axis is larger than when the bottom surface is a flat surface, the signal can be detected in a wider range, and the change in permeability can be accurately detected. Therefore, the sensor sensitivity is increased. In the case of the present invention, since the outer diameter is 18 mm and the gap 22 is 1 mm as an example, this curved surface is R10. Further, it is preferable that the gaps 21 between the tips of the opposing C-shaped soft magnetic bodies are close to each other. Also in this case, since the area of the bottom surface of the soft magnetic part with respect to the rotation axis can be increased, it is possible to accurately detect a change in permeability. However, the gap 21 needs to be larger than the gap 22 between the rotating shaft and the C-shaped soft magnetic material. If the air gap 21 is made smaller than the air gap 22, the magnetic flux 20 flowing out from the tip of the soft magnetic portion passes through the air gap 21 and flows into the tip of the opposite soft magnetic portion rather than the surface of the rotating shaft, and sensor sensitivity is reduced. . However, if the gap 21 is too large, the area of the bottom surface of the soft magnetic part facing the rotation axis becomes small, which is not preferable because the sensor sensitivity is lowered. The gap 21 is preferably 1.2 to 5 times as large as the gap 22.
励磁・検出コイル４または５で発生する磁束２０は、磁気ヘッドの軟磁性体片ごと流れ、図８に示すように、Ｃ字形軟磁性体先端に流れ込んだ磁束は空隙２２を介して回転軸へ流れる。その回転軸へ流れ込んだ磁束が、対向するＣ字形軟磁性体先端に流れることで磁気回路を構成する。このように回転軸表面の±４５°に生じている透磁率を検出することが可能となる。ここで図８は図４のＣ字形軟磁性体１を正面にみた図である。 The magnetic flux 20 generated by the excitation / detection coil 4 or 5 flows along with the soft magnetic material piece of the magnetic head. As shown in FIG. 8, the magnetic flux that flows into the tip of the C-shaped soft magnetic material passes through the gap 22 to the rotating shaft. Flowing. A magnetic circuit is configured by the magnetic flux flowing into the rotating shaft flowing at the tip of the opposing C-shaped soft magnetic material. Thus, it is possible to detect the magnetic permeability generated at ± 45 ° on the surface of the rotating shaft. FIG. 8 is a front view of the C-shaped soft magnetic body 1 of FIG.
U字型コアよりC字型コアの方が好適である理由について説明する。回転軸にU字型またはC字型コアを1つ装着し、トルク0〜200Nmを付与したときの透磁率変化を測定した。なお、コアには代表例としてMn-Znフェライトを用い、その中心部に励磁・検出コイルを100ターン巻回し、検出周波数10kHz、励磁電流10mAとした。図９に空隙２１とセンサ感度の相関関係を示す。センサ感度Sは式（１）として定義した。 The reason why the C-shaped core is preferable to the U-shaped core will be described. The permeability change was measured when one U-shaped or C-shaped core was attached to the rotating shaft and a torque of 0 to 200 Nm was applied. As a representative example, Mn-Zn ferrite was used for the core, and an excitation / detection coil was wound 100 turns around the center to obtain a detection frequency of 10 kHz and an excitation current of 10 mA. FIG. 9 shows the correlation between the gap 21 and the sensor sensitivity. Sensor sensitivity S was defined as equation (1).
ここでTは回転軸に付与したトルク、△Lはトルク０Nmにおけるインダクタンスとトルク200Nmにおけるインダクタンスの差である。図９より、空隙２１が小さくなるにつれ、センサ感度が高くなることが明らかである。ただし前記したように、空隙２１は空隙２２よりも大きい必要がある。図９で空隙２１の9mmという設定は図１０(a)に示すU字型コアである。空隙1.5mm、3mmおよび5mmは図１０(b)に示すC字型コアである。U字型コア、すなわち空隙２１が大きい場合、図１１（a）に示すように回転軸表面に流れる磁束は疎である。一方、図１１(b)に示すようにC字型コア、すなわち空隙２１が小さい場合、回転軸表面に流れる磁束は密である。よってC字型コアの方が回転軸表面の±45°に生じている透磁率変化を検出しやすく、センサ感度が高くなる。 Here, T is the torque applied to the rotating shaft, and ΔL is the difference between the inductance at a torque of 0 Nm and the inductance at a torque of 200 Nm. From FIG. 9, it is clear that the sensor sensitivity increases as the gap 21 becomes smaller. However, as described above, the gap 21 needs to be larger than the gap 22. In FIG. 9, the setting of the gap 21 of 9 mm is the U-shaped core shown in FIG. The gaps of 1.5 mm, 3 mm, and 5 mm are C-shaped cores shown in FIG. When the U-shaped core, that is, the gap 21 is large, the magnetic flux flowing on the surface of the rotating shaft is sparse as shown in FIG. On the other hand, as shown in FIG. 11B, when the C-shaped core, that is, the gap 21 is small, the magnetic flux flowing on the surface of the rotating shaft is dense. Therefore, the C-shaped core is easier to detect the magnetic permeability change occurring at ± 45 ° on the surface of the rotating shaft, and the sensor sensitivity is increased.
図１２にU字型コアの空隙２１を小さくした例を図示する。この場合、次の点が問題になる。
（１）図１２(b)に示すように、磁極先端以外からの漏れ磁束が多くなる。したがって回転軸表面に磁束が流れにくくなり、センサ感度が低下する。
（２）励磁／検出コイルを巻く場所が狭くなり、コイル巻き数が限定される。そのためセンサの高感度化が困難になる。
以上のことから、トルクセンサの磁極部分はU字型よりもC字型が好適である。
FIG. 12 illustrates an example in which the gap 21 of the U-shaped core is reduced. In this case, the following points become problems.
(1) As shown in FIG. 12B, the leakage magnetic flux from other than the tip of the magnetic pole increases. Therefore, it becomes difficult for the magnetic flux to flow on the surface of the rotating shaft, and the sensor sensitivity decreases.
(2) The place where the excitation / detection coil is wound becomes narrow, and the number of coil turns is limited. This makes it difficult to increase the sensitivity of the sensor.
From the above, the magnetic pole part of the torque sensor is preferably C-shaped rather than U-shaped.
前記磁気ヘッドを得る手段として、互いの部品を切削や鍛造、鋳造などで個別に製作した後に、接着やネジ止め等によって組み立てを行なう手法が選択できる。 As a means for obtaining the magnetic head, it is possible to select a method in which each component is individually manufactured by cutting, forging, casting or the like and then assembled by bonding, screwing, or the like.
励磁・検出コイルの巻線方式としては、図１４（ｄ）のトルクセンサのごとく軟磁性体片の各々へソレノイド状に巻き付ける方式の他に、図４〜７に記載のごとくＣ字形軟磁性体を取り囲む様に一様に巻回することができる。この方式は、巻線作業が容易であり、回転軸が振動し、コイルと接触することによって断線する危険性が無いため、より高い構造信頼性を得ることができる。 As the winding method of the excitation / detection coil, a C-shaped soft magnetic material as shown in FIGS. Can be wound uniformly to surround. In this method, winding work is easy, and there is no risk of disconnection due to vibration of the rotating shaft and contact with the coil, so that higher structural reliability can be obtained.
さらに、図４〜７に記載のごとく、Ｃ字形軟磁性体の外周側面及び内周に励磁・検出コイルを設けることによって、回転軸表面の透磁率変化量を検出しトルクの絶対値とトルクの印加方向を識別することができる。このコイルの巻き方は個々のＣ字形軟磁性体にコイルを巻く手間が省け、製造プロセスが簡略化される。 Further, as shown in FIGS. 4 to 7, by providing excitation / detection coils on the outer peripheral side surface and inner periphery of the C-shaped soft magnetic material, the amount of change in permeability on the surface of the rotating shaft is detected, and the absolute value of the torque and the torque The application direction can be identified. This method of winding the coil saves the trouble of winding the coil around each C-shaped soft magnetic material, and simplifies the manufacturing process.
本発明により、トルクを検出する回転軸への複雑な追加工が不要になる。また、回転軸の回転振れが生じた場合であっても、軸がコイルに接触し、断線させる危険性が無いことから、磁気ヘッド部分の構造信頼性が向上する。さらに、励磁・検出コイルの巻線処理が容易なため、装置全体としての生産性も向上する。また、コイルの巻数を容易に増やすことができ、高いセンサ感度が得られる。 The present invention eliminates the need for complicated additional work on the rotating shaft that detects torque. Further, even when a rotational runout of the rotary shaft occurs, there is no risk of the shaft coming into contact with the coil and disconnection, so that the structural reliability of the magnetic head portion is improved. Further, since the winding process of the excitation / detection coil is easy, the productivity of the entire apparatus is improved. Further, the number of turns of the coil can be easily increased, and high sensor sensitivity can be obtained.
以下、本発明の実施形態について図面とともに説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
（全体構成）
本発明の磁歪式トルク検出装置の一実施形態を示す。磁気ヘッドは図６に示すように、回転軸の長手方向に対して４５度の傾斜角を有する４つのＣ字形軟磁性体８〜１１が回転軸の外周方向に並んでいる。Ｃ字形軟磁性体はMn-Zn系フェライト、コイル４をボビン兼軟磁性部位置だし冶具に巻回し、コイル５はＣ字形軟磁性体の外周に巻回した。図６は前記Ｃ字形軟磁性体の外周側および内周側へ励磁・検出用のコイルを巻回して磁気ヘッドを形成し、被験物である回転軸１０を挿入した例を示す。なお、回転軸はニッケル・モリブデン鋼を使用した。
(overall structure)
1 shows an embodiment of a magnetostrictive torque detection device of the present invention. As shown in FIG. 6, in the magnetic head, four C-shaped soft magnetic bodies 8 to 11 having an inclination angle of 45 degrees with respect to the longitudinal direction of the rotating shaft are arranged in the outer peripheral direction of the rotating shaft. The C-shaped soft magnetic material was Mn-Zn ferrite, and the coil 4 was wound around the bobbin / soft magnetic portion positioning jig, and the coil 5 was wound around the outer periphery of the C-shaped soft magnetic material. FIG. 6 shows an example in which a magnetic head is formed by winding an excitation / detection coil around the outer peripheral side and the inner peripheral side of the C-shaped soft magnetic material, and a rotating shaft 10 as a test object is inserted. The rotating shaft was nickel / molybdenum steel.
回転軸の外径はΦ18mm、ボビンの内径はΦ34mm、Ｃ字形軟磁性体と回転軸の空隙は1mmとした。励磁・検出コイルにはΦ0.5mmのエナメル線を使用し、ボビン及びＣ字形軟磁性体の外周側に１００ターンづつ巻回し、コイル同士を直列に接続した。なお交流電流の周波数は10ｋHzとした。 The outer diameter of the rotating shaft was 18 mm, the inner diameter of the bobbin was 34 mm, and the gap between the C-shaped soft magnetic material and the rotating shaft was 1 mm. The excitation / detection coil used was a Φ0.5mm enameled wire, wound around the bobbin and the outer periphery of the C-shaped soft magnetic material by 100 turns, and the coils were connected in series. The frequency of the alternating current was 10 kHz.
回転軸へ−２００〜＋２００Ｎｍのトルクを付与した時の、コイルのインダクタンス変化を実測したものを図１３に示す。図より、トルクを付与した時のインダクタンス変化は良好な直線性を示すことが解かる。従って、本発明の構成に回路処理を加えれば、極めて直線性の良い出力信号が得られることになる。 FIG. 13 shows an actual change in the inductance of the coil when a torque of −200 to +200 Nm is applied to the rotating shaft. From the figure, it can be seen that the inductance change when torque is applied exhibits good linearity. Therefore, if circuit processing is added to the configuration of the present invention, an output signal with extremely good linearity can be obtained.
１：Ｃ字形軟磁性体A
２：Ｃ字形軟磁性体B
３：回転軸
４：励磁・検出コイルA
５：励磁・検出コイルB
６：Ｃ字形軟磁性体C
７：Ｃ字形軟磁性体D
８：Ｃ字形軟磁性体E
９：Ｃ字形軟磁性体F
10：Ｃ字形軟磁性体G
11：Ｃ字形軟磁性体H
12：Ｃ字形軟磁性体I
13：Ｃ字形軟磁性体J
14：Ｃ字形軟磁性体K
15：Ｃ字形軟磁性体L
16：Ｃ字形軟磁性体M
17：Ｃ字形軟磁性体N
18：Ｃ字形軟磁性体O
19：Ｃ字形軟磁性体P
20：磁束
21：Ｃ字形軟磁性体先端間の空隙
22：Ｃ字形軟磁性体と回転軸間の空隙
102：回転軸
110：軟磁性ヨーク
113：励磁・検出コイル
115：軟磁性体片
201：磁束
1: C-shaped soft magnetic material A
2: C-shaped soft magnetic material B
3: Rotating shaft 4: Excitation / detection coil A
5: Excitation / detection coil B
6: C-shaped soft magnetic material C
7: C-shaped soft magnetic material D
8: C-shaped soft magnetic material E
9: C-shaped soft magnetic material F
10: C-shaped soft magnetic material G
11: C-shaped soft magnetic material H
12: C-shaped soft magnetic material I
13: C-shaped soft magnetic material J
14: C-shaped soft magnetic material K
15: C-shaped soft magnetic material L
16: C-shaped soft magnetic material M
17: C-shaped soft magnetic material N
18: C-shaped soft magnetic material O
19: C-shaped soft magnetic material P
20: Magnetic flux
21: Cavity between tips of C-shaped soft magnetic material
22: Cavity between C-shaped soft magnetic material and rotating shaft
102: Rotation axis
110: Soft magnetic yoke
113: Excitation / detection coil
115: Soft magnetic piece
201: Magnetic flux
Claims (7)
The torque sensor according to any one of claims 1 to 6, wherein the gap is 1.2 to 5 times larger than a gap between the C-shaped soft magnetic body and the rotation shaft.
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| JP2006106016A JP2007278865A (en) | 2006-04-07 | 2006-04-07 | Magnetostrictive torque detecting apparatus |
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|---|---|---|---|
| JP2006106016A JP2007278865A (en) | 2006-04-07 | 2006-04-07 | Magnetostrictive torque detecting apparatus |
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| JP2011093061A (en) * | 2009-10-30 | 2011-05-12 | Waida Seisakusho:Kk | Rotation spindle with torque detection function |
| JP2016200552A (en) * | 2015-04-14 | 2016-12-01 | 日立金属株式会社 | Torque sensor |
| JP2018040665A (en) * | 2016-09-07 | 2018-03-15 | 日立金属株式会社 | Coil for torque sensor, and torque sensor |
| JP6483778B1 (en) * | 2017-10-11 | 2019-03-13 | シナノケンシ株式会社 | Magnetostrictive torque detection sensor |
| JP2020041803A (en) * | 2018-09-06 | 2020-03-19 | 多摩川精機株式会社 | Strain sensor structure |
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