JP3092755B2 - Temperature compensation device for differential magnetic sensor - Google Patents

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は、差動磁気式センサの温
度補償装置に関し、例えば磁歪式トルクセンサの温度補
償装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensator for a differential magnetic sensor, and more particularly to a temperature compensator for a magnetostrictive torque sensor.

【０００２】[0002]

【従来の技術】特開平３ー１８３９２４号公報は、磁歪
膜に温度変化が生じると励磁コイルの励磁電流が変化
し、その結果として両磁歪膜の透磁率を個別に検出する
一対の検出コイルの誘導電圧に差が生じる問題を解決す
るために、励磁コイルに通電する励磁電流の変化により
磁歪膜近傍の温度を検出し、検出結果に基づいて上記誘
導電圧の差を補償する磁歪式トルクセンサを開示してい
る。これにより誘導電圧差に比例する検出トルクの零点
が温度変動によって変化するのが補償される。2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 3-183924 discloses that when a temperature change occurs in a magnetostrictive film, an exciting current of an exciting coil changes, and as a result, a pair of detection coils for individually detecting the magnetic permeability of both magnetostrictive films. In order to solve the problem that a difference occurs in the induced voltage, a magnetostrictive torque sensor that detects the temperature in the vicinity of the magnetostrictive film by a change in the exciting current supplied to the exciting coil and compensates for the difference in the induced voltage based on the detection result. Has been disclosed. This compensates for a change in the zero point of the detected torque proportional to the induced voltage difference due to the temperature fluctuation.

【０００３】[0003]

【発明が解決しようとする課題】しかしながら上記した
零点補償方式では、回転軸の軸方向の温度勾配による二
つの磁歪膜間の透磁率の差により生じる出力電圧の零点
変動までは補償することができなかった。また、両磁歪
膜近傍間に温度差があると両磁歪膜と回転軸との間の熱
膨張率の差などにより歪みが生じ、その結果、両磁歪膜
間の透磁率に差が生じ、両検出コイルの誘導電圧の差出
力の零点は変動する。なおこの零点とはトルク０時にお
けるセンサの出力電位をいう。また同様の理由により、
両検出コイルの温度変化に対する感度（単位トルク量当
たりの出力電圧変化量）変化の割合が異なるので、上記
温度勾配があると感度誤差が生じる。However, the above-mentioned zero point compensation method can compensate for the zero point fluctuation of the output voltage caused by the difference in the magnetic permeability between the two magnetostrictive films due to the temperature gradient in the axial direction of the rotating shaft. Did not . Also, if there is a temperature difference between the vicinity of the two magnetostrictive films, distortion occurs due to a difference in thermal expansion coefficient between the two magnetostrictive films and the rotation axis, and as a result, a difference occurs in the magnetic permeability between the two magnetostrictive films, The zero point of the difference output of the induced voltage of the detection coil fluctuates. The zero point refers to the output potential of the sensor when the torque is 0. Also for the same reason,
Since the rate of change in the sensitivity (output voltage change per unit torque) of the two detection coils with respect to the temperature change is different, a sensitivity error occurs if the temperature gradient exists.

【０００４】このような問題は、磁歪式トルクセンサだ
けでなく一対の検出コイルの誘導電圧の差に基づいて被
測定量を検出する差動磁気式センサに共通する問題であ
る。本発明は、上記実情に鑑みてなされたものであり、
一対の検出コイルの誘導電圧の差に基づいて被測定量を
検出する差動磁気式センサにおける両検出コイル間の温
度差に基づく出力誤差を低減する温度補償装置を提供す
ることを、解決すべき技術課題とする。[0004] Such a problem is a problem common to not only the magnetostrictive torque sensor but also a differential magnetic sensor that detects an amount to be measured based on a difference between induced voltages of a pair of detection coils. The present invention has been made in view of the above circumstances,
To provide a temperature compensating device for reducing an output error based on a temperature difference between two detection coils in a differential magnetic sensor that detects a measured quantity based on a difference between induced voltages of a pair of detection coils. Technical issues.

【０００５】[0005]

【課題を解決するための手段】本発明の差動磁気式セン
サの温度補償装置は、回転軸表面に軸方向へ互いに所定
間隔を隔てて被着され磁歪特性が異なる一対の磁歪膜
と、該両磁歪膜を交流磁化させる励磁コイルと、前記両
磁歪膜近傍に配設され前記回転軸のトルクにより変調さ
れた誘導電圧を個別に出力する一対の検出コイルと、前
記誘導電圧の差に基づいて前記トルクを検出する回路部
とを備える差動磁気式センサに配設され、前記各検出コ
イルに対応するように配置され前記両検出コイル近傍の
温度を検出する一対の温度検出手段と、前記両検出コイ
ル間の温度差により生じる前記回路部の出力誤差を補償
する補償手段とを備える差動磁気式センサの温度補償装
置において、前記一対の温度検出手段は、前記各検出コ
イルに対応する位置にて前記回転軸に非接触に巻回され
た一対の無誘導コイルからなることを特徴としている。 A temperature compensating device for a differential magnetic sensor according to the present invention is provided with a pair of magnetostrictive films having different magnetostrictive characteristics which are attached to the surface of a rotating shaft at predetermined intervals in the axial direction.
An exciting coil for AC magnetizing the magnetostrictive films;
It is arranged near the magnetostrictive film and is modulated by the torque of the rotating shaft.
A pair of detection coils that individually output the induced voltage is disposed in the differential magnetic sensor and a circuit unit for detecting the torque based on a difference of the induced voltage, corresponding to the respective detection coils Differential magnetic sensor comprising: a pair of temperature detecting means arranged in such a manner as to detect the temperature in the vicinity of the two detecting coils; and a compensating means for compensating for an output error of the circuit portion caused by a temperature difference between the two detecting coils. In the temperature compensating device of the above, the pair of temperature detecting means may be each of the detecting cores.
Wound around the rotary shaft in a non-contact manner at the position corresponding to the
And a pair of non-inductive coils.

【０００６】好適な態様において、前記無誘導コイル
は、前記励磁コイル及び検出コイルの径方向内側かつ前
記磁歪膜の径方向外側で、かつ、前記励磁コイル、検出
コイル及び磁歪膜と軸方向に重なる位置に配置されてい
ることを特徴としている。 In a preferred aspect, the non-inductive coil is
Is located radially inside and in front of the excitation coil and the detection coil.
Radially outside the magnetostrictive film, and the excitation coil,
It is located at a position that overlaps the coil and the magnetostrictive film in the axial direction.
It is characterized by that.

【０００７】[0007]

【０００８】[0008]

【作用】被測定部位に互いに所定間隔を隔てて配設され
た一対の検出コイルは、信号磁界の変化によりそれぞれ
誘導電圧を誘起し、回路部は両誘導電圧の差に関連する
被測定量を検出する。両検出コイルに個別に近接配置さ
れる一対の温度検出手段は両検出コイル近傍の温度を個
別に検出し、補償手段は両検出コイル近傍の間の温度差
に基づく回路部の出力誤差を補償する。A pair of detection coils, which are arranged at a predetermined distance from each other at a portion to be measured, each induce an induced voltage due to a change in a signal magnetic field, and a circuit section detects a measured quantity related to a difference between the two induced voltages. To detect. A pair of temperature detecting means individually disposed close to the two detecting coils individually detect the temperature near the two detecting coils, and the compensating means compensates for an output error of the circuit unit based on a temperature difference between the two detecting coils. .

【０００９】[0009]

【発明の効果】以上説明したように本発明の磁気式セン
サの温度補償装置は、両検出コイル近傍の温度を個別に
検出する一対の温度検出手段と、これら検出温度の差に
より生じるセンサの出力誤差を補償する補償手段とを備
え、これら温度検出手段は、磁歪式トルクセンサの検出
コイルに対応する位置にて回転軸に非接触に巻回された
一対の無誘導コイルからなるので、両検出コイル間の温
度差により生じる零点誤差や感度誤差などの出力誤差の
補償を実現することができ、従来より格段に高精度な差
動磁気式センサを実現することができる。As described above, the temperature compensating device for a magnetic sensor according to the present invention comprises a pair of temperature detecting means for individually detecting temperatures near both detecting coils, and an output of the sensor caused by a difference between the detected temperatures. Compensating means for compensating for the error , and these temperature detecting means detect the temperature of the magnetostrictive torque sensor.
Wound non-contact with the rotating shaft at the position corresponding to the coil
Because it consists of a pair of non-inductive coils, it is possible to compensate for output errors such as zero point errors and sensitivity errors caused by temperature differences between the two detection coils, realizing a differential magnetic sensor with much higher accuracy than before. can do.

【００１０】[0010]

【実施例】【Example】

（実施例１）以下、図面を参照して本発明の一実施例を
図１のブロック回路図及び図２のコイル部分の斜視図を
参照して説明する。この磁歪式トルクセンサ（本発明で
いう差動磁気式センサ）は、図１に示すように、回転軸
１の表面に軸方向へ所定間隔を隔てて被着される磁歪膜
２ａ、２ｂと、磁歪膜２ａ、２ｂを交流磁化させる励磁
コイル３ａ，３ｂと、磁歪膜２ａ、２ｂ表面に小間隔を
隔てて個別に巻装された検出コイル４ａ、４ｂと、検出
コイル４ａ、４ｂの誘導電圧の差からトルクを検出する
回路部５と、磁歪膜２ａ、２ｂの表面に小間隔を隔てて
個別に巻装された無誘導コイル（本発明でいう温度検出
手段）６ａ、６ｂと、無誘導コイル６ａ、６ｂから出力
される温度検出信号の差により回路部５の出力を補償す
る補償回路（本発明でいう補償手段）７とを備えてい
る。(Embodiment 1) An embodiment of the present invention will be described below with reference to the block circuit diagram of FIG. 1 and a perspective view of a coil portion of FIG. 2 with reference to the drawings. As shown in FIG. 1, the magnetostrictive torque sensor (differential magnetic sensor according to the present invention) includes magnetostrictive films 2a and 2b attached to the surface of a rotating shaft 1 at predetermined intervals in an axial direction. Excitation coils 3a and 3b for AC-magnetizing the magnetostrictive films 2a and 2b, detection coils 4a and 4b individually wound on the surfaces of the magnetostrictive films 2a and 2b at small intervals, and induced voltages of the detection coils 4a and 4b. A circuit section 5 for detecting torque from the difference, non-inductive coils (temperature detecting means in the present invention) 6a and 6b individually wound on the surfaces of the magnetostrictive films 2a and 2b at small intervals, and a non-inductive coil A compensation circuit (compensation means in the present invention) 7 for compensating the output of the circuit section 5 based on the difference between the temperature detection signals output from 6a and 6b.

【００１１】回転軸１として直径２０ｍｍのＳ４５Ｃ焼
き入れ鋼を用い、その表面に減圧溶射法により磁歪膜２
ａ、２ｂを被着した。磁歪膜２ａ、２ｂは、Ｆｅ，Ｎ
ｉ，Ｃｒが４０，５６，４の重量組成比をもち、回転軸
１にほぼ等しい熱膨張率をもつ鉄ニッケル合金からな
る。この合金の飽和磁束密度は１１ｋＧ、電気抵抗率は
７０μΩ・ｃｍである。磁歪膜２ａ、２ｂはそれぞれ軸
方向に４０ｍｍの幅をもち、磁歪膜２ａ、２ｂ間の軸方
向間隔は１０ｍｍとし、厚さは数百μｍとした。被着
後、磁気異方性を付与するために機械加工により軸方向
に対し±４５度のスパイラル溝を形成した。スパイラル
溝の幅は約１ｍｍ、そのピッチは約４．５ｍｍとした。As the rotating shaft 1, a hardened S45C steel having a diameter of 20 mm is used, and a magnetostrictive film 2 is formed on its surface by a low pressure spraying method.
a, 2b were applied. The magnetostrictive films 2a and 2b are made of Fe, N
i, Cr is composed of an iron-nickel alloy having a weight composition ratio of 40, 56, 4 and a thermal expansion coefficient substantially equal to that of the rotating shaft 1. This alloy has a saturation magnetic flux density of 11 kG and an electric resistivity of 70 μΩ · cm. Each of the magnetostrictive films 2a and 2b has a width of 40 mm in the axial direction, the axial interval between the magnetostrictive films 2a and 2b is 10 mm, and the thickness is several hundred μm. After the application, spiral grooves of ± 45 degrees with respect to the axial direction were formed by machining to impart magnetic anisotropy. The width of the spiral groove was about 1 mm, and the pitch was about 4.5 mm.

【００１２】励磁コイル３ａ及び検出コイル４ａは二本
のエナメル線を磁歪膜２ａの位置に巻装して形成され
る。励磁コイル３ｂ及び検出コイル４ｂも磁歪膜２ｂの
位置に同様に巻装してなる。これらコイルは図示しない
薄肉の樹脂ボビン表面に巻装され、このボビンが回転軸
１に小空隙を隔てて嵌着されている。励磁コイル３ａ及
び検出コイル４ａの軸方向コイル幅は１５ｍｍで内径は
２５ｍｍ、ターン数はそれぞれ１５０回とされ、図２
（ａ），（ｂ）に示すように、まず無誘導コイル６ａ、
６ｂを巻装後、励磁コイル３ａ、３ｂを巻装し、その上
に検出コイル４ａ、４ｂを巻装している。無誘導コイル
６ａは二本のエナメル線を互いにペアに隣接する状態で
同時に巻装されて形成され、両エナメル線の一端部は短
絡され、それらの両他端がこの無誘導コイル６ａの両端
となる。無誘導コイル６ａの軸方向幅は０．８ｍｍ、内
径は２２ｍｍとした（図３参照）。このように巻装する
ことにより無誘導コイル６ａのインダクタンスは実質的
に０となる。無誘導コイル６ｂも同様に作製され、励磁
コイル３ｂ、検出コイル４ｂ及び無誘導コイル６ｂも上
記と同様に巻装した。The excitation coil 3a and the detection coil 4a are formed by winding two enamel wires at the position of the magnetostrictive film 2a.
You. The exciting coil 3b and the detecting coil 4b are similarly wound around the position of the magnetostrictive film 2b. These coils are wound around the surface of a thin resin bobbin (not shown), and the bobbin is fitted to the rotating shaft 1 with a small gap therebetween. The axial coil width of the exciting coil 3a and the detecting coil 4a is 15 mm, the inner diameter is 25 mm, and the number of turns is 150, respectively.
(A), (b), first, the non-inductive coil 6a,
After winding 6b, the exciting coils 3a and 3b are wound, and the detection coils 4a and 4b are wound thereon. The non-inductive coil 6a is formed by simultaneously winding two enamel wires in a state of being adjacent to each other in a pair. Become. The axial width of the non-induction coil 6a was 0.8 mm, and the inner diameter was 22 mm (see FIG. 3). By winding in this manner, the inductance of the non-inductive coil 6a becomes substantially zero. The non-inductive coil 6b was manufactured similarly, and the exciting coil 3b, the detection coil 4b, and the non-inductive coil 6b were wound in the same manner as described above.

【００１３】次に回路部５及びこの磁歪式トルクセンサ
のトルク検出動作を説明する。励磁コイル３ａ，３ｂは
両者の形成磁界方向が逆方向となるように直列接続さ
れ、交流電源（ここでは５０ｋＨｚ）３から電流制限抵
抗Ｒを通じて給電される。これにより検出コイル４ａ、
４ｂに誘導電圧が発生する。検出コイル４ａの巻き終わ
り端及び検出コイル４ｂの巻き始め端は接地され、検出
コイル４ａの巻き始め端及び検出コイル４ｂの巻き終わ
り端はそれぞれ、検波回路５ａ、５ｂにより個別に検波
されて差動アンプ５１の正負の入力端に個別に入力され
る。その結果、差動アンプ５１は検出コイル４ａ、４ｂ
の両誘導電圧の検波出力差に比例した信号電圧をローパ
スフィルタ５２に出力し、ローパスフィルタ５２はこの
信号電圧に重畳するキャリヤ成分や高周波ノイズ成分を
除去して、直流信号成分Ｖｓを出力する。Next, the circuit section 5 and the torque detecting operation of the magnetostrictive torque sensor will be described. The exciting coils 3a and 3b are connected in series so that the directions of the formed magnetic fields are opposite to each other, and are supplied from an AC power source (here, 50 kHz) 3 through a current limiting resistor R. Thereby, the detection coil 4a,
An induced voltage is generated at 4b. The winding end of the detection coil 4a and the winding start of the detection coil 4b are grounded, and the winding start of the detection coil 4a and the winding end of the detection coil 4b are individually detected by detection circuits 5a and 5b, respectively. The positive and negative input terminals of the amplifier 51 are individually input. As a result, the differential amplifier 51 detects the detection coils 4a, 4b
And outputs a signal voltage proportional to the detection output difference between the two induced voltages to the low-pass filter 52. The low-pass filter 52 removes a carrier component and a high-frequency noise component superimposed on the signal voltage and outputs a DC signal component Vs.

【００１４】いま回転軸１にトルクを与えると回転軸１
に捩じれが生じ、この捩じれにより磁歪膜２ａ、２ｂの
透磁率が変化する。磁歪膜２ａ、２ｂのトルク−透磁率
特性（磁歪特性）は互いに逆の特性となっているので、
検出コイル４ａ、４ｂの誘導電圧の差はトルクの大きさ
及び方向に応じた値となる。図４の（ａ）に室温（摂氏
１５度）時のトルク−出力電圧特性を示し、図４の
（ｂ）に回転軸１の一端を摂氏８０度に加熱した場合の
トルク−出力電圧（Ｅｏ）特性を示す。図４の（ａ）、
（ｂ）からわかるように、磁歪膜２ａ、２ｂ間に温度差
が生じると、トルク変動に対する出力電圧変化に比べて
大きな零点ドリフトＥ’が発生する。When a torque is applied to the rotating shaft 1, the rotating shaft 1
Is twisted, and the twist changes the magnetic permeability of the magnetostrictive films 2a and 2b. Since the torque-permeability characteristics (magnetostriction characteristics) of the magnetostrictive films 2a and 2b are opposite to each other,
The difference between the induced voltages of the detection coils 4a and 4b is a value corresponding to the magnitude and direction of the torque. FIG. 4A shows a torque-output voltage characteristic at room temperature (15 degrees Celsius), and FIG. 4B shows a torque-output voltage (Eo) when one end of the rotating shaft 1 is heated to 80 degrees Celsius. ) Characteristic. FIG. 4A,
As can be seen from (b), when a temperature difference occurs between the magnetostrictive films 2a and 2b, a large zero point drift E 'occurs as compared with the output voltage change due to the torque fluctuation.

【００１５】磁歪膜２ａ、２ｂ間の温度差と出力電位Ｖ
ｓの変動（零点ドリフト）との関係を図５に示す。な
お、この温度差は回転軸１に熱電対を固定して測定し
た。図５のヒステリシスは温度伝播遅れによるものと推
定される。次に、無誘導コイル６ａ，６ｂ及び補償回路
（補償手段）７の構成と動作を説明する。The temperature difference between the magnetostrictive films 2a and 2b and the output potential V
FIG. 5 shows the relationship with the variation of s (zero point drift). This temperature difference was measured with a thermocouple fixed to the rotating shaft 1. The hysteresis in FIG. 5 is presumed to be due to a temperature propagation delay. Next, the configuration and operation of the non-inductive coils 6a and 6b and the compensation circuit (compensation means) 7 will be described.

【００１６】無誘導コイル６ａ、６ｂは直列接続され、
無誘導コイル６ａの高位端ａは、定電流電源Ｅから電位
Ｖａを給電され、無誘導コイル６ｂの低位端ｃは接地さ
れ、無誘導コイル６ａの低位端と無誘導コイル６ｂの高
位端とは直列接続節点ｂとなっている。以下、各点ａ、
ｂ、ｃの電位をＶａ、Ｖｂ、Ｖｃとする。電位Ｖａ、Ｖ
ｂ、Ｖｃは、補償回路７に入力される。The non-inductive coils 6a and 6b are connected in series,
High end a free induction coil 6a is powered potential Va from the constant current power supply E, lower end c of non-inductive coil 6b is grounded, lower end of the non-inductive coil 6a and the high end of the non-inductive coil 6b Is a series connection node b. Hereinafter, each point a,
Let the potentials of b and c be Va, Vb and Vc. Potentials Va, V
b and Vc are input to the compensation circuit 7.

【００１７】補償回路７は、電位Ｖａ、Ｖｂ、Ｖｃ間の
加減算を行うアナログ加減算器７１と、ローパスフィル
タ５２の出力電圧Ｖｓからアナログ減算器７２の出力電
圧Ｖｄを減算するアナログ減算器７２とからなる。この
ような加減算器７１及び減算器７２は周知のオペアンプ
回路で作製できる。ここで、無誘導コイル６ａの抵抗を
Ｒ１、その両端の電位差をＶ１、無誘導コイル６ｂの抵
抗をＲ２、その両端の電位差をＶ２、Ｒ１及びＲ２に通
電される電流をｉとすれば、 ｉ×（Ｒ１−Ｒ２）＝Ｖ１−Ｖ２＝（Ｖａ−Ｖｂ）−（Ｖｂ−Ｖｃ） ＝Ｖａ＋Ｖｂ−２Ｖｃ したがって、無誘導コイル６ａ、６ｂの抵抗差（Ｒ１−
Ｒ２）を求めるには、（Ｖａ＋Ｖｂ−２Ｖｃ）の加減算
をアナログ加減算器７１で行えばよい。その結果、アナ
ログ加減算器７１の出力電圧Ｖｄは抵抗差（Ｒ１−Ｒ
２）に比例し、抵抗差（Ｒ１−Ｒ２）は検出コイル４
ａ、４ｂの温度差にほぼ比例するので、信号電圧Ｖｓか
らこの温度補償電圧Ｖｄを減算すれば、温度差による検
出コイル４ａ、４ｂの零点ドリフトを無誘導コイル６ａ
の抵抗差で相殺することができる。なお当然、電圧Ｖｄ
と電圧Ｖｓとの比率は加減算器７１及び減算器７２など
の増幅率調節により適当な値に設定される。The compensating circuit 7 comprises an analog adder / subtractor 71 for performing addition and subtraction between the potentials Va, Vb and Vc, and an analog subtractor 72 for subtracting the output voltage Vd of the analog subtractor 72 from the output voltage Vs of the low-pass filter 52. Become. Such an adder / subtractor 71 and a subtractor 72 can be manufactured by a well-known operational amplifier circuit. Here, assuming that the resistance of the non-inductive coil 6a is R1, the potential difference between both ends is V1, the resistance of the non-inductive coil 6b is R2, the potential difference between both ends is V2, and the current supplied to R1 and R2 is i. × (R1−R2) = V1−V2 = (Va−Vb) − (Vb−Vc) = Va + Vb−2Vc Therefore, the resistance difference between the non-inductive coils 6a and 6b (R1−
In order to obtain (R2), the addition / subtraction of (Va + Vb−2Vc) may be performed by the analog adder / subtractor 71. As a result, the output voltage Vd of the analog adder / subtractor 71 becomes equal to the resistance difference (R1-R
2), the resistance difference (R1-R2) is
Since the temperature compensation voltage Vd is substantially proportional to the temperature difference between the detection coils 4a and 4b, the zero point drift of the detection coils 4a and 4b due to the temperature difference can be reduced by subtracting the temperature compensation voltage Vd from the signal voltage Vs.
Can be offset by the difference in resistance. Of course, the voltage Vd
The ratio between the voltage and the voltage Vs is set to an appropriate value by adjusting the amplification factor of the adder / subtractor 71 and the subtractor 72.

【００１８】温度Ｔと無誘導コイル６ａ、６ｂの抵抗値
Ｒとの関係を表す特性図を図６に示し、無誘導コイル６
ａ、６ｂの抵抗差（Ｒ１−Ｒ２）と出力信号電圧Ｖｓの
零点ドリフト量Ｅ’との関係を図７に示す。更に、回転
軸１の一端を摂氏２２から８０度の範囲で加熱した場合
の出力信号電圧Ｖｓの零点ドリフト量Ｅ’との補償前後
の関係を図８に示す。ただし室温は摂氏２２度とした。
また、回転軸１の一端を摂氏８０度に加熱した場合のト
ルクと補償後の出力信号電圧Ｖｓｃとの関係を図４の
（ｃ）に示す。FIG. 6 is a characteristic diagram showing the relationship between the temperature T and the resistance value R of the non-inductive coils 6a and 6b.
FIG. 7 shows the relationship between the resistance difference (R1−R2) between a and 6b and the zero-point drift amount E ′ of the output signal voltage Vs. Further, FIG. 8 shows the relationship before and after the compensation with the zero-point drift amount E ′ of the output signal voltage Vs when one end of the rotating shaft 1 is heated in the range of 22 to 80 degrees Celsius. However, the room temperature was 22 degrees Celsius.
FIG. 4C shows the relationship between the torque when the one end of the rotating shaft 1 is heated to 80 degrees Celsius and the compensated output signal voltage Vsc.

【００１９】上記説明から、無誘導コイル６ａ、６ｂと
補償回路７との簡単な構成により磁歪式トルクセンサの
零点補償を実現でき、精度を大幅に改善できることがわ
かる。 （実施例２）本発明の他の実施例を図９により説明す
る。From the above description, it can be seen that the zero point compensation of the magnetostrictive torque sensor can be realized by a simple configuration of the non-inductive coils 6a and 6b and the compensation circuit 7, and the accuracy can be greatly improved. (Embodiment 2) Another embodiment of the present invention will be described with reference to FIG.

【００２０】この実施例は図１の補償回路７から出力さ
れる電圧Ｖｄ、Ｖｓｃを用いて上記温度勾配により生じ
る感度誤差を補償する回路であって、増幅率Ｋのアンプ
７３と、アンプ７３の出力電圧Ｖｄ’と零点補償出力電
圧Ｖｓｃとを掛けるアナログ乗算回路（又は可変利得回
路）７４とからなる。磁歪膜２ａ、２ｂ間の温度勾配に
比例する無誘導コイル６ａ、６ｂ間の抵抗差（Ｒ１ーＲ
２）と電圧Ｖｓｃの感度との関係を図１０に示す。温度
勾配の増大によりセンサが高感度化することがわかる。
すなわち、単位トルク変動当たりの出力電圧Ｖｓの大
きさ（感度）は、温度差０の場合に比べて温度差すなわ
ち抵抗差（Ｒ１−Ｒ２）が増加するほど増大する。This embodiment is a circuit for compensating for a sensitivity error caused by the above-mentioned temperature gradient by using the voltages Vd and Vsc output from the compensation circuit 7 shown in FIG. An analog multiplication circuit (or variable gain circuit) 74 multiplies the output voltage Vd 'by the zero point compensation output voltage Vsc. The resistance difference (R1-R) between the non-inductive coils 6a, 6b is proportional to the temperature gradient between the magnetostrictive films 2a, 2b.
FIG. 10 shows the relationship between 2) and the sensitivity of the voltage Vsc. It can be seen that the sensitivity of the sensor is increased by increasing the temperature gradient.
That is, the magnitude (sensitivity) of the output voltage Vs per unit torque change increases as the temperature difference, that is, the resistance difference (R1−R2) increases, as compared with the case where the temperature difference is zero.

【００２１】したがって図１０の感度変化曲線を一本の
直線Ｍで代表し、この直線Ｍの勾配ｍと逆数関係にある
勾配（１／ｍ）となるようにアンプ７３の増幅率Ｋ（＝
１／ｍ）を設定すれば、アナログ乗算回路（又は可変利
得回路）７４の出力電圧Ｖｏは温度勾配により感度が変
化しないようにできる。なお、アンプ７３を折れ線アン
プ（すなわちオペアンプにダイオード、抵抗、直流電源
により折れ線カーブの増幅率が設定されたアンプ）を用
いれば更に高精度で感度補償することができる。また、
図１０の特性と逆特性のマップをマイコンのロムに内蔵
しておき、ソフトウエアにより同じ処理を行うこともで
きる。 （実施例３）他の実施例を図１１により説明する。Therefore, the sensitivity change curve shown in FIG. 10 is represented by a single straight line M, and the amplification factor K (= m) of the amplifier 73 is set so that the slope (1 / m) is inversely related to the slope m of the straight line M.
1 / m), the sensitivity of the output voltage Vo of the analog multiplication circuit (or variable gain circuit) 74 does not change due to the temperature gradient. If the amplifier 73 is a polygonal amplifier (that is, an amplifier in which the amplification factor of the polygonal curve is set by an operational amplifier with a diode, a resistor, and a DC power supply), the sensitivity can be compensated with higher accuracy. Also,
The map of the characteristic opposite to the characteristic shown in FIG. 10 may be built in the ROM of the microcomputer, and the same processing may be performed by software. (Embodiment 3) Another embodiment will be described with reference to FIG.

【００２２】この実施例は実施例１（図１）の処理を他
の回路で実施したものである。８１、８２、８３は減算
器、８４は加算器である。In this embodiment, the processing of the first embodiment (FIG. 1) is performed by another circuit. 81, 82 and 83 are subtractors, and 84 is an adder.

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

【図１】実施例１の磁歪式トルクセンサのブロック回路
図、FIG. 1 is a block circuit diagram of a magnetostrictive torque sensor according to a first embodiment;

【図２】図１の回転軸近傍部分の斜視図、FIG. 2 is a perspective view of a portion near a rotation shaft of FIG. 1;

【図３】図１の無誘導コイルの斜視図、FIG. 3 is a perspective view of the non-induction coil of FIG. 1;

【図４】図１のセンサのトルクー出力電圧との関係を示
す特性図、FIG. 4 is a characteristic diagram showing a relationship between a torque and an output voltage of the sensor of FIG. 1;

【図５】図１のセンサの温度差と零点ドリフトとの関係
を示す特性図、FIG. 5 is a characteristic diagram showing a relationship between a temperature difference and a zero point drift of the sensor of FIG. 1;

【図６】図１の無誘導コイルのコイル温度とコイル抵抗
との関係を示す特性図、FIG. 6 is a characteristic diagram showing a relationship between a coil temperature and a coil resistance of the non-inductive coil of FIG. 1;

【図７】図１の無誘導コイルの抵抗差とセンサの出力電
圧の零点ドリフトとの関係を示す特性図、FIG. 7 is a characteristic diagram showing a relationship between a resistance difference of the non-inductive coil of FIG. 1 and a zero point drift of an output voltage of the sensor.

【図８】温度勾配と出力電圧誤差の零点変動量との補償
前後の関係を示す特性図、FIG. 8 is a characteristic diagram showing a relationship between a temperature gradient and a zero-point variation amount of an output voltage error before and after compensation.

【図９】実施例２の補償回路を示すブロック回路図、FIG. 9 is a block circuit diagram illustrating a compensation circuit according to a second embodiment;

【図１０】図１のセンサの温度差（抵抗差）と感度変動
との関係を示す特性図、10 is a characteristic diagram showing a relationship between a temperature difference (resistance difference) and a sensitivity variation of the sensor of FIG.

【図１１】他の実施例を示す回路図、FIG. 11 is a circuit diagram showing another embodiment;

【符号の説明】[Explanation of symbols]

１は回転軸、２ａ、２ｂは磁歪膜、３ａ，３ｂは励磁コ
イル、４ａ、４ｂは検出コイル、５は回路部、６ａ、６
ｂは無誘導コイル（本発明でいう温度検出手段）、７は
補償回路（補償手段）、1 is a rotating shaft, 2a and 2b are magnetostrictive films, 3a and 3b are excitation coils, 4a and 4b are detection coils, 5 is a circuit section, 6a and 6
b is a non-inductive coil (temperature detecting means in the present invention), 7 is a compensation circuit (compensating means),

───────────────────────────────────────────────────── フロントページの続き (72)発明者 柏木 陽一郎 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 (56)参考文献 特開 平１−173842（ＪＰ，Ａ) 特開 平４−175627（ＪＰ，Ａ) 特開 平３−273125（ＪＰ，Ａ) 実開 昭63−27842（ＪＰ，Ｕ) 実開 昭56−23429（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) G01L 3/10 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichiro Kashiwagi 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (56) References JP-A-1-173842 (JP, A) JP-A Heisei 4-175627 (JP, A) JP-A-3-273125 (JP, A) JP-A 63-27842 (JP, U) JP-A 56-23429 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 3/10

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】回転軸表面に軸方向へ互いに所定間隔を隔
てて被着され磁歪特性が異なる一対の磁歪膜と、該両磁
歪膜を交流磁化させる励磁コイルと、前記両磁歪膜近傍
に配設され前記回転軸のトルクにより変調された誘導電
圧を個別に出力する一対の検出コイルと、前記誘導電圧
の差に基づいて前記トルクを検出する回路部とを備える
差動磁気式センサに配設され、 前記各検出コイルに対応するように配置され前記両検出
コイル近傍の温度を検出する一対の温度検出手段と、前
記両検出コイル間の温度差により生じる前記回路部の出
力誤差を補償する補償手段とを備える差動磁気式センサ
の温度補償装置において、 前記一対の温度検出手段は、前記各検出コイルに対応す
る位置にて前記回転軸に非接触に巻回された一対の無誘
導コイルからなることを特徴とする差動磁気式センサの
温度補償装置。 1. A pair of magnetostrictive films having different magnetostriction characteristics, which are attached to the surface of a rotating shaft at predetermined intervals in the axial direction and have different magnetostriction characteristics.
An excitation coil for AC-magnetizing the strained film, and near the two magnetostrictive films.
A differential magnetic sensor comprising: a pair of detection coils that are individually disposed to output an induced voltage modulated by the torque of the rotating shaft, and a circuit unit that detects the torque based on a difference between the induced voltages. A pair of temperature detecting means disposed to correspond to each of the detecting coils and detecting a temperature near the two detecting coils, and compensating for an output error of the circuit portion caused by a temperature difference between the two detecting coils. A temperature compensating device for a differential magnetic sensor , comprising: a pair of temperature detecting means corresponding to each of the detecting coils.
A pair of uninvited coils wound around the rotating shaft
A differential magnetic sensor characterized by comprising a conducting coil.
Temperature compensation device. 【請求項２】前記無誘導コイルは、前記励磁コイル及び
検出コイルの径方向内側かつ前記磁歪膜の径方向外側
で、かつ、前記励磁コイル、検出コイル及び磁歪膜と軸
方向に重なる位置に配置されている請求項１記載の差動
磁気式センサの温度補償装置。 2. The non-inductive coil according to claim 1 , wherein
Radially inside the detection coil and radially outside the magnetostrictive film
And the excitation coil, the detection coil, the magnetostrictive film and the shaft
2. The differential according to claim 1, wherein the differential is arranged at a position overlapping in the direction.
Temperature compensation device for magnetic sensors.