JP2009121862A - Force sensor - Google Patents

Force sensor Download PDF

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JP2009121862A
JP2009121862A JP2007293954A JP2007293954A JP2009121862A JP 2009121862 A JP2009121862 A JP 2009121862A JP 2007293954 A JP2007293954 A JP 2007293954A JP 2007293954 A JP2007293954 A JP 2007293954A JP 2009121862 A JP2009121862 A JP 2009121862A
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force
magnetic field
permanent magnet
pressure
yoke
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Masamitsu Kitahashi
正光 北橋
Yutaka Yoshinada
裕 吉灘
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Komatsu Ltd
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Komatsu Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To reduce the effects of hysteresis in a force sensor using a magnetostrictive element. <P>SOLUTION: The force sensor is provided with a pressure-receiving plate 212 having a pressure-receiving surface for receiving a force from the outside; a force-receiving member 216 made of a magnetostrictive element; a yoke 210 made of a magnetic substance; a permanent magnet 214 for generating a main magnetic field passing through the yoke 210 and the force-receiving member 216; a permanent magnet 218 for generating a reverse magnetic field in a direction opposite to the magnetic field generated by the permanent magnet 214; and a Hall IC 220 for detecting magnetic flux of the magnetic field passing through the yoke 210 and the force-receiving member 216. The pressure-receiving plate 212; the permanent magnet 214; the force-receiving member 216; and the permanent magnet 218 are serially arranged in this order along the direction of the force from the outside received by the pressure-receiving plate 212. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、磁歪素子を用いた力センサに関し、特に、ヒステリシスの影響を軽減し、かつ簡単な構成の力センサに関する。   The present invention relates to a force sensor using a magnetostrictive element, and more particularly to a force sensor having a simple structure that reduces the influence of hysteresis.

従来、磁歪素子と呼ばれる磁性合金に圧力をかけると、磁歪素子が変形することによって透磁率が変化することを利用した力センサが知られている。例えば、特許文献１には、バイアス磁界をかけて温度特性を改善した圧力センサが記載されている。特許文献２には、ホール素子を用いたホールＩＣで磁歪素子の透磁率変化に伴う磁束変化を検出する圧力センサが記載されている。
特開２０００−２６６６２１号公報 特開２００５−３７２６４号公報 2. Description of the Related Art Conventionally, a force sensor is known that utilizes a change in permeability when a pressure is applied to a magnetic alloy called a magnetostrictive element, and the magnetostrictive element is deformed. For example, Patent Document 1 describes a pressure sensor that improves temperature characteristics by applying a bias magnetic field. Patent Document 2 describes a pressure sensor that detects a change in magnetic flux accompanying a change in permeability of a magnetostrictive element with a Hall IC using a Hall element.
JP 2000-266621 A JP 2005-37264 A

特許文献１及び２のいずれの圧力センサも、磁歪素子等が持つヒステリシスにより、高い精度を得ることができない。特に特許文献１の場合、バイアス磁界をかけることにより温度特性及び出力特性の安定性を向上することができても、依然としてヒステリシスの問題は残る。   In any of the pressure sensors of Patent Documents 1 and 2, high accuracy cannot be obtained due to the hysteresis of the magnetostrictive element or the like. In particular, in the case of Patent Document 1, even if the stability of temperature characteristics and output characteristics can be improved by applying a bias magnetic field, the problem of hysteresis still remains.

そこで、本発明の目的は、磁歪素子を用いた力センサにおいて、ヒステリシスの影響を低減することである。   Accordingly, an object of the present invention is to reduce the influence of hysteresis in a force sensor using a magnetostrictive element.

本発明の一つの実施態様に従う力センサ（１）は、外部からの力を受ける受圧面を有する受圧面部材（２１２）と、磁歪素子からなる受力部材（２１６）と、磁性体からなるヨーク（２１０）と、前記ヨーク及び前記受力部材を通る磁界を生成する磁界生成用磁石（２１４）と、前記磁界生成用磁石が生成する磁界の向きとは逆向きの磁界を生成する逆磁界用磁石（２１８）と、前記ヨーク及び前記受力部材を通る磁界の磁束を検出する磁束検出手段（２２０）と、を備える。そして、前記受圧面が受ける外部からの力の方向に、前記受圧面部材、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石が、前記受圧面部材、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石の順に直列に配置されている。   The force sensor (1) according to one embodiment of the present invention includes a pressure receiving surface member (212) having a pressure receiving surface that receives an external force, a force receiving member (216) made of a magnetostrictive element, and a yoke made of a magnetic material. (210), a magnetic field generating magnet (214) that generates a magnetic field that passes through the yoke and the force receiving member, and a reverse magnetic field that generates a magnetic field opposite to the direction of the magnetic field generated by the magnetic field generating magnet. A magnet (218); and magnetic flux detection means (220) for detecting magnetic flux of a magnetic field passing through the yoke and the force receiving member. And in the direction of the external force received by the pressure receiving surface, the pressure receiving surface member, the magnetic field generating magnet, the force receiving member, and the reverse magnetic field magnet are the pressure receiving surface member, the magnetic field generating magnet, The force receiving member and the reverse magnetic field magnet are arranged in series in this order.

好適な実施態様では、前記受圧面が外部からの力を受けたとき、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石は、いずれも加圧されるようにしてもよい。   In a preferred embodiment, when the pressure receiving surface receives an external force, all of the magnetic field generating magnet, the force receiving member, and the reverse magnetic field magnet may be pressurized.

好適な実施態様では、前記磁束検出手段は、ホール素子を用いたホールＩＣであってもよい。   In a preferred embodiment, the magnetic flux detection means may be a Hall IC using a Hall element.

以下、本発明の一実施形態に係る力センサ１について、図面を参照して説明する。   Hereinafter, a force sensor 1 according to an embodiment of the present invention will be described with reference to the drawings.

図１は、本実施形態に係る力センサ１の内部構造を示す断面図である。   FIG. 1 is a cross-sectional view showing the internal structure of the force sensor 1 according to this embodiment.

本実施形態では、流体の圧力を測定するセンサであって、特に作業機械などの作動油の油圧を測定する油圧センサを例に説明する。   In the present embodiment, a sensor that measures the pressure of a fluid and that measures the hydraulic pressure of hydraulic oil such as a working machine will be described as an example.

本実施形態に係る力センサ１は、非磁性金属（例えばステンレス）などで形成された上ケース１１０及び下ケース１１２を有する。上ケース１１０と下ケース１１２はボルト１１４によって結合されている。下ケース１１２には、作動油導入口１１６が設けられている。そして、下ケース１１２内の作動油導入口１１６と連通する収容部１１８には、円柱形状のピン１２０が収容されている。ピン１２０は、作動油導入口１１６に流入した作動油の圧力を受圧プレート２１２に伝達する。また、収容部１１８の壁面とピン１２０の側面とは密着している。収容部１１８の壁面に設けられた溝にＯリング１２２が収容されていて、作動油が漏れ出さないようになっている。   The force sensor 1 according to the present embodiment includes an upper case 110 and a lower case 112 made of a nonmagnetic metal (for example, stainless steel). The upper case 110 and the lower case 112 are connected by a bolt 114. The lower case 112 is provided with a hydraulic oil inlet 116. A cylindrical pin 120 is accommodated in the accommodating portion 118 that communicates with the hydraulic oil inlet 116 in the lower case 112. The pin 120 transmits the pressure of the hydraulic oil flowing into the hydraulic oil inlet 116 to the pressure receiving plate 212. Further, the wall surface of the accommodating portion 118 and the side surface of the pin 120 are in close contact. An O-ring 122 is accommodated in a groove provided on the wall surface of the accommodating portion 118 so that hydraulic fluid does not leak out.

上ケース１１０及び下ケース１１２に形成される内部の空間には、純鉄などで形成された略円筒形状のヨーク２１０と、ピン１２０から力を受ける円板形状の受圧プレート２１２と、ヨーク２１０の内部に配置された略円柱形状の永久磁石２１４と、ヨーク２１０の内部に配置された略円柱形状の磁歪素子からなる受力部材２１６と、ヨーク２１０の外側に配置された略円柱形状の永久磁石２１８とを有する。受圧プレート２１２、永久磁石２１４、受力部材２１６及び永久磁石２１８は、受圧プレート２１２が受ける力の方向に直列に並んでいる。   In the internal space formed in the upper case 110 and the lower case 112, a substantially cylindrical yoke 210 made of pure iron, a disk-shaped pressure receiving plate 212 that receives force from the pin 120, and a yoke 210 A substantially cylindrical permanent magnet 214 disposed inside, a force receiving member 216 composed of a substantially cylindrical magnetostrictive element disposed inside the yoke 210, and a substantially cylindrical permanent magnet disposed outside the yoke 210. 218. The pressure receiving plate 212, the permanent magnet 214, the force receiving member 216, and the permanent magnet 218 are arranged in series in the direction of the force received by the pressure receiving plate 212.

また、力センサ１は、ヨーク２１０の蓋体２０２を支持するためのガイド１２４を備える。ガイド１２４は、ボルト１２６によって上ケース１１０と結合されている。これにより、蓋体２０２と永久磁石２１８が上ケース１１０に対して固定される。さらに、このガイド１２４が固定された上ケース１１０がボルト１１４により下ケース１１２に固定されることにより、ヨーク２１０内に収容される永久磁石２１４及び受力部材２１６、並びに受圧プレート２１２が相互に密着するように固定される。これにより、受圧プレート２１２が受ける力の方向に直列に並んだ受圧プレート２１２、永久磁石２１４、受力部材２１６及び永久磁石２１８は、それぞれケース１１０，１１２内で移動しないように固定されている。   Further, the force sensor 1 includes a guide 124 for supporting the lid 202 of the yoke 210. The guide 124 is coupled to the upper case 110 by a bolt 126. Thereby, the lid 202 and the permanent magnet 218 are fixed to the upper case 110. Further, the upper case 110 to which the guide 124 is fixed is fixed to the lower case 112 by the bolt 114, whereby the permanent magnet 214 and the force receiving member 216 accommodated in the yoke 210 and the pressure receiving plate 212 are in close contact with each other. To be fixed. Thereby, the pressure receiving plate 212, the permanent magnet 214, the force receiving member 216, and the permanent magnet 218 arranged in series in the direction of the force received by the pressure receiving plate 212 are fixed so as not to move in the cases 110 and 112, respectively.

ヨーク２１０は、ヨーク本体２０１と蓋体２０２とを有する。ヨーク本体２０１と蓋体２０２との接触部分にはギャップが生じないように、ヨーク本体２０１と蓋体２０２とは密着している。また、ヨーク本体２０１の側壁の外周面は、上ケース１１０の内周面と接している。   The yoke 210 has a yoke body 201 and a lid 202. The yoke body 201 and the lid body 202 are in close contact so that a gap does not occur at the contact portion between the yoke body 201 and the lid body 202. Further, the outer peripheral surface of the side wall of the yoke body 201 is in contact with the inner peripheral surface of the upper case 110.

受圧プレート２１２は、ヨーク本体２０１の底面に設けられた、受圧プレート２１２より僅かに大きい円形状の孔に嵌め込まれている。受圧プレート２１２の下面はピン１２０と当接している。そして、ピン１２０により押されると、受圧プレート２１２がヨーク２１０に対して僅かに移動するとともに、その力を永久磁石２１４へ伝達する。このときにヨーク２１０は上下のケース１１０，１１２により固定されているので移動しない。受圧プレート２１２がヨーク２１０に対して相対的に移動するときの受圧プレート２１２とヨーク２１０との間の摩擦を極力減らすために、両者の接触部分にはグリースが塗られている。本実施形態のように受圧プレート２１２をヨーク２１０とは別体とすることにより、ピン１２０によって押されたときにヨーク２１０全体が撓むことを防止できるとともに、ピン１２０の加圧力を永久磁石２１４、受力部材２１６及び永久磁石２１８へ確実に伝達できる。   The pressure receiving plate 212 is fitted into a circular hole provided on the bottom surface of the yoke body 201 and slightly larger than the pressure receiving plate 212. The lower surface of the pressure receiving plate 212 is in contact with the pin 120. When pressed by the pin 120, the pressure receiving plate 212 slightly moves with respect to the yoke 210 and transmits the force to the permanent magnet 214. At this time, the yoke 210 does not move because it is fixed by the upper and lower cases 110 and 112. In order to reduce friction between the pressure receiving plate 212 and the yoke 210 as much as possible when the pressure receiving plate 212 moves relative to the yoke 210, grease is applied to the contact portion between the two. By making the pressure receiving plate 212 separate from the yoke 210 as in the present embodiment, the yoke 210 as a whole can be prevented from bending when pressed by the pin 120, and the pressure applied to the pin 120 can be reduced by the permanent magnet 214. The force receiving member 216 and the permanent magnet 218 can be reliably transmitted.

略円柱形状の永久磁石２１４は、図１に示すように作動油導入口が下になるように配置したときの天井面及び底面がそれぞれ磁極となる。永久磁石２１４の底面は、受圧プレート２１２と密着している。つまり、永久磁石２１４にも、受圧プレート２１２を介してピン１２０が受けた力が、底面から天井面へ向けた軸方向に加わる。永久磁石２１４の天井面は、移動しないように固定された受力部材２１６と密着しているので、永久磁石２１４が受圧プレート２１２から押圧されると、永久磁石２１４は軸方向へ加圧される。永久磁石２１４が生成する磁界（以下、主磁界と称する）の磁束は、受力部材２１６、ヨーク２１０及び受圧プレート２１２を通過する。   As shown in FIG. 1, the substantially cylindrical permanent magnet 214 has a magnetic pole on the ceiling surface and the bottom surface when the hydraulic oil introduction port is disposed below. The bottom surface of the permanent magnet 214 is in close contact with the pressure receiving plate 212. That is, the force received by the pin 120 via the pressure receiving plate 212 is also applied to the permanent magnet 214 in the axial direction from the bottom surface to the ceiling surface. Since the ceiling surface of the permanent magnet 214 is in close contact with the force receiving member 216 fixed so as not to move, when the permanent magnet 214 is pressed from the pressure receiving plate 212, the permanent magnet 214 is pressed in the axial direction. . A magnetic flux generated by the permanent magnet 214 (hereinafter referred to as a main magnetic field) passes through the force receiving member 216, the yoke 210, and the pressure receiving plate 212.

略円柱形状の受力部材２１６の底面は、永久磁石２１４と密着している。そして、受力部材２１６には、受圧プレート２１２及び永久磁石２１４を介してピン１２０が受けた力が、底面から天井面へ向けた軸方向に加わる。受力部材２１６の天井面は、移動しないように固定されたヨーク２１０の蓋体２０２の下面と密着しているので、受力部材２１６が永久磁石２１４から押圧されると、受力部材２１６は軸方向へ加圧される。   The bottom surface of the substantially cylindrical force receiving member 216 is in close contact with the permanent magnet 214. The force received by the pin 120 via the pressure receiving plate 212 and the permanent magnet 214 is applied to the force receiving member 216 in the axial direction from the bottom surface to the ceiling surface. Since the ceiling surface of the force receiving member 216 is in close contact with the lower surface of the lid 202 of the yoke 210 fixed so as not to move, when the force receiving member 216 is pressed from the permanent magnet 214, the force receiving member 216 is Pressurized in the axial direction.

受力部材２１６は、磁歪素子で構成されるが、磁歪素子の中でも極めて磁歪が大きい超磁歪素子であってもよい。磁歪素子とは、機械的な応力が印加されると、その透磁率が変化する素子である。超磁歪素子とは、この透磁率の変化が非常に大きいものを指す。超磁歪素子としては、例えば、Ｔｂ０．３４Ｄｙ０．６６Ｆｅ１．８８等がある。従って、受力部材２１６は、上述のように加圧されると透磁率が変化する。   The force receiving member 216 is composed of a magnetostrictive element, but may be a super magnetostrictive element having extremely large magnetostriction among the magnetostrictive elements. A magnetostrictive element is an element whose magnetic permeability changes when mechanical stress is applied. The giant magnetostrictive element refers to an element having a very large change in magnetic permeability. Examples of the giant magnetostrictive element include Tb0.34Dy0.66Fe1.88. Therefore, when the force receiving member 216 is pressed as described above, the magnetic permeability changes.

略円柱形状の永久磁石２１８は、図１に示すように作動油導入口が下になるように配置したときの天井面及び底面がそれぞれ磁極となる。永久磁石２１８の磁極の向きは、永久磁石２１４の磁極の向きとは反対向きである。つまり、永久磁石２１８の底面と永久磁石２１４の天井面が同極となる。これにより、永久磁石２１８が生成する磁界は、永久磁石２１４が生成する磁界に対して逆向きとなる。そこで、永久磁石２１８が生成する磁界を、以下逆磁界と称する。永久磁石２１８は、上ケース１１０に設けられた収容空間内に収容されている。永久磁石２１８の底面はヨーク２１０の蓋体２０２の上面と密着している。永久磁石２１８の天井面は上ケース１１０の収容空間の内壁と接し、動かないように固定されている。そして、永久磁石２１８には、受圧プレート２１２、永久磁石２１４、蓋体２０２及び受力部材２１６を介してピン１２０が受けた力が伝達され、軸方向に加圧される。   As shown in FIG. 1, the substantially cylindrical permanent magnet 218 has a magnetic pole on the ceiling surface and the bottom surface when the hydraulic oil introduction port is arranged downward. The direction of the magnetic pole of the permanent magnet 218 is opposite to the direction of the magnetic pole of the permanent magnet 214. That is, the bottom surface of the permanent magnet 218 and the ceiling surface of the permanent magnet 214 have the same polarity. Thereby, the magnetic field generated by the permanent magnet 218 is opposite to the magnetic field generated by the permanent magnet 214. Therefore, the magnetic field generated by the permanent magnet 218 is hereinafter referred to as a reverse magnetic field. The permanent magnet 218 is accommodated in an accommodation space provided in the upper case 110. The bottom surface of the permanent magnet 218 is in close contact with the top surface of the lid body 202 of the yoke 210. The ceiling surface of the permanent magnet 218 is in contact with the inner wall of the accommodation space of the upper case 110 and is fixed so as not to move. The force received by the pin 120 is transmitted to the permanent magnet 218 via the pressure receiving plate 212, the permanent magnet 214, the lid 202, and the force receiving member 216, and is pressed in the axial direction.

図２は、本実施形態に係る力センサ１の磁束の分布状態の説明図である。同図には、永久磁石２１４が生成する主磁界（点線矢印）、及び永久磁石２１８が生成する逆磁界（実線矢印）を示す。なお、同図において、永久磁石２１４，２１８の右側の領域の主磁界及び逆磁界のみ示す。同図に示すように、ホールＩＣ２２０のところで、主磁界の磁束及び逆磁界の磁束が正反対の方向となっている。これにより、本実施形態に係る力センサ１は、永久磁石２１４、受力部材２１６、永久磁石２１８に圧力が加わったときに、後述するように、それぞれのヒステリシスを互いに弱めあうことができる。   FIG. 2 is an explanatory diagram of a magnetic flux distribution state of the force sensor 1 according to the present embodiment. In the figure, a main magnetic field (dotted arrow) generated by the permanent magnet 214 and a reverse magnetic field (solid arrow) generated by the permanent magnet 218 are shown. In the figure, only the main magnetic field and the reverse magnetic field in the region on the right side of the permanent magnets 214 and 218 are shown. As shown in the figure, at the Hall IC 220, the main magnetic flux and the reverse magnetic flux are in opposite directions. As a result, the force sensor 1 according to the present embodiment can weaken the respective hysteresis when pressure is applied to the permanent magnet 214, the force receiving member 216, and the permanent magnet 218, as will be described later.

図３は、ヨーク２１０の蓋体２０２を通るＡ−Ａ断面図である。   FIG. 3 is a cross-sectional view taken along line AA through the lid 202 of the yoke 210.

同図に示すように、蓋体２０２と上ケース１１０の間には隙間が空いている。蓋体２０２は、中心部材２０３と円周部材２０４とから構成されている。中心部材２０３は円周部材２０４に向かう突起部２０３Ａを有し、円周部材２０４も中心部材２０３へ向かう突起部２０４Ａを有する。これらの突起部２０３Ａ，２０４Ａ同士の間には隙間が設けられている。この隙間には、ホールＩＣ２２０が配置されている。   As shown in the figure, there is a gap between the lid 202 and the upper case 110. The lid body 202 includes a center member 203 and a circumferential member 204. The central member 203 has a protrusion 203 </ b> A toward the circumferential member 204, and the circumferential member 204 also has a protrusion 204 </ b> A toward the central member 203. A gap is provided between the protrusions 203A and 204A. A Hall IC 220 is disposed in this gap.

ホールＩＣ２２０は、内部にホール素子を有するＩＣである。ホールＩＣ２２０は、ホール素子を通過する磁束の量を電圧として検出することができる磁束検出手段である。従って、ホールＩＣ２２０は、内部のホール素子を通過する磁束の量が変化すると、出力する電圧が変化する。   The Hall IC 220 is an IC having a Hall element inside. The Hall IC 220 is magnetic flux detection means that can detect the amount of magnetic flux passing through the Hall element as a voltage. Accordingly, the output voltage of the Hall IC 220 changes when the amount of magnetic flux passing through the internal Hall element changes.

ところで、本実施形態では、ピン１２０が作動油の圧力を受けると、その力が永久磁石２１４、受力部材２１６及び永久磁石２１８のいずれにもかかる。このとき、磁歪素子からなる受力部材２１６は、かかった圧力に応じてその透磁率が変化する。受力部材２１６の透磁率が変化すると、受力部材２１６を通過する磁束が変化する。本実施形態ではこの磁束の変化を検出して、受圧プレート２１２が受けた力を検出する。   By the way, in this embodiment, when the pin 120 receives the pressure of the hydraulic oil, the force is applied to any of the permanent magnet 214, the force receiving member 216, and the permanent magnet 218. At this time, the magnetic permeability of the force receiving member 216 made of a magnetostrictive element changes according to the applied pressure. When the magnetic permeability of the force receiving member 216 changes, the magnetic flux passing through the force receiving member 216 changes. In this embodiment, the change of the magnetic flux is detected, and the force received by the pressure receiving plate 212 is detected.

すなわち、本実施形態では、図２に示したように、永久磁石２１４が生成する主磁界の磁束の大部分は、受力部材２１６、ヨーク２１０，及び受圧プレート２１２の内部を通過し、空気中に漏れることはほとんどない。そして、ヨーク２１０の蓋体２０２の隙間の部分を通過する磁束の大半がホールＩＣ２２０を通過する。従って、ホールＩＣ２２０は、受力部材２１６の透磁率の変化に伴う磁束の変化のほぼすべてを検出することができるので、圧力の変化を正確に検出することができる。これは、受圧プレート２１２、永久磁石２１４、受力部材２１６及びヨーク２１０で構成される磁気回路において、受力部材２１６が磁束の可変抵抗として挙動することを意味する。   That is, in this embodiment, as shown in FIG. 2, most of the magnetic flux of the main magnetic field generated by the permanent magnet 214 passes through the inside of the force receiving member 216, the yoke 210, and the pressure receiving plate 212, and is in the air. There is almost no leak. Then, most of the magnetic flux passing through the gap portion of the lid body 202 of the yoke 210 passes through the Hall IC 220. Therefore, the Hall IC 220 can detect almost all of the change in the magnetic flux accompanying the change in the magnetic permeability of the force receiving member 216, so that the change in pressure can be accurately detected. This means that in the magnetic circuit composed of the pressure receiving plate 212, the permanent magnet 214, the force receiving member 216, and the yoke 210, the force receiving member 216 behaves as a variable resistance of magnetic flux.

図４は、本実施形態に係る力センサ１を用いて測定した作動油圧とホールＩＣ２２０の出力電圧との関係を示す。すなわち、図４のグラフは、作動油圧を０〜５０ＭＰａまで５ＭＰａ刻みで上昇させたときのホールＩＣ２２０の出力電圧（測定値を■で示す）と、作動油圧を５０〜０ＭＰａまで５ＭＰａ刻みで下降させたときのホールＩＣ２２０の出力電圧（測定値を◆で示す）とを測定した結果を示す。   FIG. 4 shows the relationship between the hydraulic pressure measured using the force sensor 1 according to the present embodiment and the output voltage of the Hall IC 220. That is, the graph of FIG. 4 shows that the output voltage (measured value is indicated by ■) of the Hall IC 220 when the operating oil pressure is increased from 0 to 50 MPa in 5 MPa increments, and the operating oil pressure is decreased from 50 to 0 MPa in 5 MPa increments. The result of measuring the output voltage (measured value is indicated by ♦) of the Hall IC 220 is shown.

なお、このときの測定条件は、（１）室温２５℃、（２）評価用圧力計：重鐘型圧力計（精度±０．０２％）、（３）流体：建設機械用作動油である。   Measurement conditions at this time are (1) room temperature 25 ° C., (2) pressure gauge for evaluation: heavy bell type pressure gauge (accuracy ± 0.02%), and (3) fluid: hydraulic fluid for construction machinery. .

同図からわかるように、本実施形態では、最大ヒステリシスは±０．６３％と非常に小さくなっている。これは、図２に示すように、ホールＩＣ２２０の部分で、主磁界及び逆磁界の磁束が正反対の向きになっているので、主磁界を生成する永久磁石２１４、逆磁界を生成する永久磁石２１８、及び受力部材２１６のすべてを同時に加圧することにより、それぞれが有するヒステリシスが互いにキャンセルされるためである。   As can be seen from the figure, in this embodiment, the maximum hysteresis is very small, ± 0.63%. As shown in FIG. 2, since the magnetic fluxes of the main magnetic field and the reverse magnetic field are in opposite directions in the Hall IC 220 portion, the permanent magnet 214 that generates the main magnetic field and the permanent magnet 218 that generates the reverse magnetic field. This is because, by simultaneously pressurizing all of the force receiving members 216, the hysteresis of each is canceled out.

本実施形態にかかる力センサによれば、ヒステリシスが大幅に低減され、高精度で力を検出することができる。   According to the force sensor according to the present embodiment, the hysteresis is greatly reduced, and the force can be detected with high accuracy.

上述した本発明の実施形態は、本発明の説明のための例示であり、本発明の範囲をそれらの実施形態にのみ限定する趣旨ではない。当業者は、本発明の要旨を逸脱することなしに、他の様々な態様で本発明を実施することができる。   The above-described embodiments of the present invention are examples for explaining the present invention, and are not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the present invention in various other modes without departing from the gist of the present invention.

本実施形態に係る力センサ１の内部構造を示す断面図である。It is sectional drawing which shows the internal structure of the force sensor 1 which concerns on this embodiment. 本実施形態に係る力センサ１の測定原理の説明図である。It is explanatory drawing of the measurement principle of the force sensor 1 which concerns on this embodiment. ヨーク２１０の蓋体２０２を通るＡ−Ａ断面図である。It is AA sectional drawing which passes along the cover body 202 of the yoke 210. FIG. 本実施形態に係る力センサ１を用いて測定した作動油圧とホールＩＣの出力電圧との関係を示す。The relationship between the hydraulic pressure measured using the force sensor 1 which concerns on this embodiment, and the output voltage of Hall IC is shown.

符号の説明Explanation of symbols

１…力センサ
１１０…上ケース
１１２…下ケース
１１６…作動油導入口
２０１…ヨーク本体
２０２…蓋体
２１０…ヨーク
２１２…受圧プレート
２１４、２１８…永久磁石
２１６ 受力部材
２２０…ホールＩＣ DESCRIPTION OF SYMBOLS 1 ... Force sensor 110 ... Upper case 112 ... Lower case 116 ... Hydraulic oil inlet 201 ... Yoke main body 202 ... Lid body 210 ... Yoke 212 ... Pressure receiving plate 214, 218 ... Permanent magnet 216 Power receiving member 220 ... Hall IC

Claims (3)

力センサ（１）であって、
外部からの力を受ける受圧面を有する受圧面部材（２１２）と、
磁歪素子からなる受力部材（２１６）と、
磁性体からなるヨーク（２１０）と、
前記ヨーク及び前記受力部材を通る磁界を生成する磁界生成用磁石（２１４）と、
前記磁界生成用磁石が生成する磁界の向きとは逆向きの磁界を生成する逆磁界用磁石（２１８）と、
前記ヨーク及び前記受力部材を通る磁界の磁束を検出する磁束検出手段（２２０）と、を備え、
前記受圧面が受ける外部からの力の方向に、前記受圧面部材、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石が、前記受圧面部材、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石の順に直列に配置されていることを特徴とする力センサ。 A force sensor (1),
A pressure-receiving surface member (212) having a pressure-receiving surface that receives external force;
A force receiving member (216) made of a magnetostrictive element;
A yoke (210) made of a magnetic material;
A magnetic field generating magnet (214) for generating a magnetic field passing through the yoke and the force receiving member;
A reverse field magnet (218) for generating a magnetic field opposite to the direction of the magnetic field generated by the magnetic field generation magnet;
Magnetic flux detection means (220) for detecting the magnetic flux of the magnetic field passing through the yoke and the force receiving member,
In the direction of the external force received by the pressure receiving surface, the pressure receiving surface member, the magnetic field generating magnet, the force receiving member, and the reverse magnetic field magnet include the pressure receiving surface member, the magnetic field generating magnet, and the force receiving force. A force sensor, wherein a member and the reverse magnetic field magnet are arranged in series in this order. 前記受圧面が外部からの力を受けたとき、前記磁界生成用磁石、前記受力部材及び前記逆磁界用磁石は、いずれも加圧されることを特徴とする請求項１記載の力センサ。   The force sensor according to claim 1, wherein when the pressure receiving surface receives an external force, the magnetic field generating magnet, the force receiving member, and the reverse magnetic field magnet are all pressurized. 前記磁束検出手段は、ホール素子を用いたホールＩＣであることを特徴とする請求項１または２に記載の力センサ。   The force sensor according to claim 1 or 2, wherein the magnetic flux detection means is a Hall IC using a Hall element.
JP2007293954A 2007-11-13 2007-11-13 Force sensor Pending JP2009121862A (en)

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