JP2004184364A - Displacement sensor - Google Patents

Displacement sensor Download PDF

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JP2004184364A
JP2004184364A JP2002354754A JP2002354754A JP2004184364A JP 2004184364 A JP2004184364 A JP 2004184364A JP 2002354754 A JP2002354754 A JP 2002354754A JP 2002354754 A JP2002354754 A JP 2002354754A JP 2004184364 A JP2004184364 A JP 2004184364A
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permanent magnet
moving body
magnetic detection
detection element
magnetic
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JP4150904B2 (en
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Takahisa Ban
隆央 伴
Tatsuya Kitanaka
達也 北中
Keiichi Yasuda
恵一 安田
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Denso Corp
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Denso Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement sensor for detecting highly accurately the displacement in the linear moving direction of a moving body. <P>SOLUTION: A housing 12 of this displacement sensor 10 is fixed to a support member by a fixing part 14. A hole IC30 is insert-molded on the tip side of a columnar member 20. A permanent magnet 50 is linearly moved together with the moving body. Assuming that the coefficient of linear expansion of the housing 12 is α<SB>1</SB>, the coefficient of linear expansion of the columnar member 20 is α<SB>2</SB>, the distance between the inside bottom part 16 of the housing 12 and the fixing face 15 of the fixing part 14 is L<SB>1</SB>, the distance between the inside bottom part 16 of the housing 12 and and the center of the two holes IC30 is L<SB>2</SB>, the elongation of the L<SB>1</SB>part of the housing 12 when the temperature is raised by ΔT is ΔL<SB>1</SB>, and the elongation of the L<SB>2</SB>part of the columnar member 20 when the temperature is raised by ΔT is ΔL<SB>2</SB>, ΔL<SB>1</SB>=L<SB>1</SB>×α<SB>1</SB>×ΔT and ΔL<SB>2</SB>=L<SB>2</SB>×α<SB>2</SB>×ΔT are established. If a condition L<SB>1</SB>/L<SB>2</SB>=α<SB>2</SB>/α<SB>1</SB>is satisfied, then the equation ΔL<SB>1</SB>=ΔL<SB>2</SB>is established. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、直線移動する移動体の変位量を検出する非接触式の変位量センサに関する。
【０００２】
【従来の技術】
永久磁石または磁気検出素子の一方が移動体とともに移動することにより永久磁石または磁気検出素子の他方に対して一方が変位し、磁気検出素子が検出する磁束密度の変化により移動体の変位量を検出する変位量センサが知られている。磁気検出素子は樹脂等のハウジングに取り付けられており、ハウジングは、移動体または支持部材に取り付けられている。
【０００３】
【発明が解決しようとする課題】
しかしながら、周囲温度の変化によりハウジングが膨張または収縮すると、移動体または支持部材に取り付けられているハウジングの取付部とハウジングに取り付けられている磁気検出素子との距離が移動体の直線移動方向に変化することがある。移動体の変位量を検出する磁気検出素子の位置が移動体の直線移動方向にずれるので、磁気検出素子が検出する磁束密度は変化する。したがって、変位量センサは移動体の変位量を高精度に検出できない。
【０００４】
また、磁気検出素子を複数用いる場合、移動体の直線移動方向に沿った永久磁石の中心軸から、磁気検出素子の検出部が永久磁石の中心軸と直交する方向にずれていると、磁気検出素子が検出する磁束密度は変化する。したがって、移動体の変位量を高精度に検出できない。
【０００５】
また、磁気検出素子を複数用いる場合、磁気検出素子の検出部同士の距離が移動体の直線移動方向に離れていると、各検出部で検出する磁束密度に差が生じ、移動体の変位量を高精度に検出できない。
本発明の目的は、移動体の直線移動方向の変位量を高精度に検出する変位量センサを提供することにある。
【０００６】
【課題を解決するための手段】
本発明の請求項１記載の変位量センサによると、ハウジングの内側底部と取付部との距離をＬ１、ハウジングの内側底部と磁気検出素子との距離をＬ２、ハウジングの線膨張係数をα１、突出部材の線膨張係数をα２とすると、Ｌ１／Ｌ２＝α２／α１である。周囲温度の変化によりハウジングおよび突出部材が膨張または収縮しても、移動体が静止している状態においてハウジングの取付部と磁気検出素子との間に形成される移動体の直線移動方向の距離はほぼ一定になる。したがって、周囲温度が変化しハウジングおよび突出部材が膨張または収縮しても、移動体の変位量を高精度に検出できる。
本発明の請求項２記載の変位量センサによると、ハウジングおよび突出部材の少なくとも一方を樹脂により容易に形成できる。
【０００７】
本発明の請求項３または４記載の変位量センサによると、磁気検出素子は複数であり、移動体の直線移動方向に沿った永久磁石の中心軸は複数の磁気検出素子の検出部の検出面の中心を貫通している。磁気検出素子が検出する磁束密度が永久磁石の中心軸と直交する方向にばらつかないので、移動体の変位量を高精度に検出できる。
【０００８】
本発明の請求項５または６記載の変位量センサによると、複数の磁気検出素子のうち２個は、検出部の検出面とパッケージの表面との間の肉厚が薄い側のパッケージの面同士を接触している。肉厚が薄い側のパッケージの面同士を接触することにより、移動体の直線移動方向における検出部同士の距離を極力短縮できる。検出部が検出する磁束密度のばらつきを低減できるので、移動体の変位量を高精度に検出できる。
さらに、肉厚が薄い側のパッケージの面同士を接触している２個の磁気検出素子の端子はパッケージから互いに離れる方向に引き出されているので、端子にリード線等を配線することが容易である。
【０００９】
本発明の請求項７記載の変位量センサによると、磁気検出素子の端子はパッケージから１８０°反対方向に引き出されている。したがって、端子にリード線等を配線することが容易である。
本発明の請求項８記載の変位量センサによると、筒孔の磁束密度は、直線移動方向の一方に向けて減少している。筒孔における磁気検出素子の直線移動方向の位置が変化することにより、磁気検出素子が検出する磁束密度が変化するので、永久磁石に対する磁気検出素子の直線移動方向の相対変位量を検出できる。したがって、永久磁石または磁気検出素子の一方が移動体とともに直線移動することにより、移動体の直線移動方向の変位量を検出できる。
【００１０】
さらに、永久磁石が直線移動方向に着磁されているので、直線移動方向に沿った筒孔の中心軸を軸として磁気検出素子に対し永久磁石が相対回動しても、磁気検出素子が検出する磁束密度は変化しない。したがって、回転しながら直線移動する移動体の変位量を検出できる。また、本来回転しない移動体の直線移動方向の変位量を高精度に検出するために必要な移動体の回転を防止する回転防止機構が不要である。部品点数が減少するので、変位量センサの構造が簡単になる。さらに、回転防止機構と摺動することによる移動体の摩耗を防止できる。
また、変位量センサに使用する永久磁石を切削あるいは成形等により１個の永久磁石で形成できるので、部品点数が減少し、変位量センサの組付が容易である。
本発明の請求項９記載の変位量センサによると、永久磁石を切削して形成する場合、永久磁石を直線的に切削すればよいので、永久磁石の加工が容易である。
【００１１】
【発明の実施の形態】
以下、本発明の実施の形態を示す実施例を図に基づいて説明する。
本発明の一実施例による変位量センサを図１に示す。変位量センサ１０は、例えば自動車のＥＧＲ（Ｅｘｈａｕｓｔ Ｇａｓ Ｒｅｃｉｒｃｕｌａｔｉｏｎ）バルブに設置される。排ガスの循環量を変化させるＥＧＲバルブのシャフト（以下、「ＥＧＲバルブのシャフト」を移動体という。）に本センサの後述する永久磁石５０を取り付け移動体とともに永久磁石５０を移動させることにより、排ガスの循環量、すなわち移動体の直線移動方向の変位量を検出する。
【００１２】
変位量センサ１０のハウジング１２は樹脂製の有底筒状である。ハウジング１２は、ハウジング１２の円筒部１３の外周側に形成されている取付部１４によりＥＧＲバルブのバルブボディ（以下、「ＥＧＲバルブのバルブボディ」を支持部材という。）等に固定されている。取付部１４の取付面１５は支持部材と接触している。
【００１３】
突出部材である柱状部材２０は樹脂製であり、永久磁石５０に向けてハウジング１２の内側底部１６から突出し、ハウジング１２の内側底部１６に固定されている。磁気検出素子であるホールＩＣ３０は柱状部材２０の先端側にインサート成形されている。ホールＩＣ３０の検出信号を取り出すターミナル１９はハウジング１２のコネクタ部１８にインサート成形されている。
【００１４】
磁気検出素子であるホールＩＣ３０は、図２に示すように、樹脂製のパッケージ３２と、磁束密度を検出するホール素子を用いた検出部３４と、端子３６とを有している。端子３６は、検出部３４に電力を供給する端子３７と、検出部３４から検出信号を取り出す端子３８とを有している。さらにホールＩＣ３０は、検出部３４の検出信号を制御する制御回路をパッケージ３２内に有している。
【００１５】
図３に示すように、２個のホールＩＣ３０は、検出部３４の検出面３５とパッケージ３２の表面との間に形成される肉厚が薄い側の面同士を接触させている。そして、端子３６は互いに離れるようにパッケージ３２から１８０°反対方向に引き出されている。２個のホールＩＣ３０は、検出部３４の検出面３５が移動体の直線移動方向に沿った永久磁石５０の中心軸１１０と直交するように柱状部材２０内に保持されている。
【００１６】
図１に示すように、移動体とともに直線移動する可動部材４０は、樹脂製のカバー４２と、カバー４２にインサート成形されている永久磁石５０とを有している。可動部材４０はハウジング１２の円筒部１３内を図１の矢印Ａ、Ｂが示す直線移動方向に往復移動可能である。可動部材４０は移動体の端部と結合または接触しているので、可動部材４０は移動体とともに直線移動する。
永久磁石５０は、移動体とともに直線移動する矢印Ａ、Ｂ方向に筒孔として貫通孔１００を有している。ホールＩＣ３０をインサート成形している柱状部材２０は、永久磁石５０に対し貫通孔１００を相対的に直線移動可能である。
【００１７】
図４の（Ａ）に示すように、貫通孔１００を形成する永久磁石５０の内周面５１は直線移動方向にほぼ同一径である。永久磁石５０の外周面５２の径は、直線移動方向の一方である矢印Ａ方向に向け直線的に減少している。したがって、永久磁石５０の直線移動方向に沿った貫通孔１００の中心軸１１０と直交する径方向の永久磁石５０の厚さは、矢印Ａ方向に向け直線的に減少している。言い換えると、永久磁石５０は、円錐台状に形成され、中心軸１１０方向に貫通する円柱状の貫通孔１００を有している。つまり、中心軸１１０と直交する永久磁石５０の断面は円環状であり、その断面積は矢印Ａ方向に向け減少している。図４の（Ｂ）に示すように、永久磁石５０は、直線移動方向の一方に向け、厚さが厚い側から薄い側に向けて着磁されている。図５に示すように、貫通孔１００における磁束密度は中心軸１１０上で一番大きく、中心軸１１０から離れると減少する。
磁性板６０は、永久磁石３０の厚さが厚い側の端面５５に接着等で固定されている。端面５５から出る磁束は磁性板６０を通り、ホールＩＣ３０の検出部３４の検出面３５をほぼ垂直に通過する。
【００１８】
変位量センサ１０の周囲温度が変化すると、ハウジング１２および柱状部材２０は膨張または収縮する。ここで、図６に示すハウジング１２の線膨張係数をα１、柱状部材２０の線膨張係数をα２とする。また、移動体の直線移動方向において、温度Ｔにおけるハウジング１２の内側底部１６と取付面１５との距離をＬ１、ハウジング１２の内側底部１６と２個のホールＩＣ３０の中心との距離をＬ２、温度Ｔから温度がΔＴ上昇するときのハウジング１２のＬ１部分の伸び量をΔＬ１、温度Ｔから温度がΔＴ上昇するときの柱状部材２０のＬ２部分の伸び量をΔＬ２とする。ΔＬ１＝Ｌ１×α１×ΔＴ、ΔＬ２＝Ｌ２×α２×ΔＴである。ここで２個のホールＩＣ３０の中心とは、２個の検出部３４同士の中間を意味している。
【００１９】
ハウジング１２および柱状部材２０が膨張または収縮しても、取付面１５と２個の磁気検出素子３０の中心との距離を一定にするためには、次式（１）を満たせばよい。

Figure 2004184364
つまり、距離Ｌ１と距離Ｌ２との比が、ハウジング１２の線膨張係数α１と柱状部材２０の線膨張係数α２との比の逆数になっていればよい。式（１）を満たすことにより、周囲温度が変化しても取付面１５と２個のホールＩＣ３０の中心との距離は変化しない。つまり、同じ位置の移動体に対しホールＩＣ３０の位置は変化しない。周囲温度が変化しハウジング１２および柱状部材２０が膨張または収縮しても、同じ位置の移動体に対しホールＩＣ３０が検出する磁束密度は変化しないので、移動体の変位量を高精度に検出できる。
【００２０】
また、２個のホールＩＣ３０は、検出部３４の検出面３５の中心を永久磁石５０の中心軸１１０が貫通するように柱状部材２０内に設置されているので、検出部３４が検出する磁束密度が中心軸１１０と直交する方向にばらつかない。したがって、移動体の変位量を高精度に検出できる。
【００２１】
また、２個のホールＩＣ３０は、検出部３４の検出面３５とパッケージ３２の表面との間に形成される肉厚が薄い側の面同士を接触させている。したがって、永久磁石５０の中心軸１１０方向に形成する２個の検出部３４の距離を極力短縮できる。２個の検出部３４が検出する磁束密度が中心軸１１０方向にばらつかないので、移動体の変位量を高精度に検出できる。
【００２２】
本発明としては、式（１）を満たしていれば、２個のホール１Ｃ３０の位置は中心軸１１０からずれていてもよい。また本発明としては、式（１）を満たしていれば、検出部３４の検出面３５とパッケージ３２の表面との間に形成される肉厚が薄い側の面と厚い側の面、あるいは肉厚の厚い側の面同士を接触させてもよい。
【００２３】
永久磁石５０の中心軸１１０方向において、取付面１５とホールＩＣ３０とが同じ位置にあれば、ハウジング１２と柱状部材２０とを同じ樹脂材で一体成形することも可能である。本実施例ではハウジング１２および柱状部材２０を樹脂材で形成したが、他の非磁性材、例えばセラミックで形成してもよい。
本実施例では、２個のホールＩＣ３０の互いの端子３６はパッケージ３２から１８０°反対方向に引き出されるように柱状部材２０内に設置されているので、端子３６をターミナル１９とを接続する配線が干渉せず配線が容易である。２個のホールＩＣ３０の端子３６が互いに離れる方向にパッケージ３２から引き出されているのであれば、端子３６が離れる方向は１８０°に限るものではなく、例えば９０°の方向に端子３６を引き出してもよい。
【００２４】
本実施例では、検出部３４と、検出部３４の検出信号を制御する図示しない制御回路とをパッケージ３２内に保持するホールＩＣ３０を特許請求の範囲に記載した磁気検出素子として用いている。これに対し、検出部３４を制御回路と分離し、検出部３４だけを柱状部材２０にインサート成形してもよい。磁気検出素子としてＭＲＥ素子または磁気抵抗素子を用いてもよい。また、ホールＩＣ３０の数は２個に限らず、１個または３個以上でもよい。
【００２５】
本実施例では、永久磁石５０の厚さの厚い側から薄い側に向けて直線移動方向に永久磁石５０を着磁した。これに対し、永久磁石５０の厚さの薄い側から厚い側に向けて直線移動方向に永久磁石５０を着磁してもよい。この場合、移動体の変位量と磁束密度の関係は反転したものになる。
【００２６】
本実施例では、永久磁石５０を筒状に形成したが、移動体が直線移動方向することによりホールＩＣ３０が検出する磁束密度が変化するのであれば、永久磁石の形状はどのような形状も可能である。
本実施例では、移動体とともに永久磁石が直線移動し、磁気検出素子としてのホールＩＣ３０が静止している。これに対し移動体とともにホールＩＣ３０が直線移動し、永久磁石が静止している構成も可能である。
【図面の簡単な説明】
【図１】本発明の一実施例による変位量センサを示す断面図である。
【図２】（Ａ）は本実施例のホールＩＣを示す正面図であり、（Ｂ）は（Ａ）のＢ方向矢視図である。
【図３】本実施例の２個のホールＩＣの接触状態を示す説明図である。
【図４】（Ａ）は本実施例による変位量センサの永久磁石を示す断面図であり、（Ｂ）は永久磁石の着磁方向を示す説明図である。
【図５】ホールＩＣの磁石軸からの距離と磁束密度の変化率との関係を示す特性図である。
【図６】（Ａ）はハウジングの膨張を示す説明図であり、（Ｂ）は柱状部材の膨張を示す説明図である。
【符号の説明】
１０ 変位量センサ
１２ ハウジング
１４ 取付部
１５ 取付面
２０ 柱状部材（突出部材）
３０ ホールＩＣ（磁気検出素子）
３２ パッケージ
３４ 検出部
３５ 検出面
３６ 端子
５０ 永久磁石
５１ 内周面
５２ 外周面
１００ 貫通孔（筒孔）
１１０ 中心軸[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-contact displacement sensor for detecting a displacement of a moving body that moves linearly.
[0002]
[Prior art]
When one of the permanent magnet or the magnetic detection element moves with the moving body, one of the permanent magnet or the magnetic detection element is displaced relative to the other, and the displacement of the moving body is detected by a change in magnetic flux density detected by the magnetic detection element. A known displacement sensor is known. The magnetic detection element is mounted on a housing made of resin or the like, and the housing is mounted on a moving body or a support member.
[0003]
[Problems to be solved by the invention]
However, when the housing expands or contracts due to a change in the ambient temperature, the distance between the mounting portion of the housing attached to the moving body or the support member and the magnetic detection element attached to the housing changes in the direction of linear movement of the moving body. Sometimes. Since the position of the magnetic detection element for detecting the displacement of the moving body is shifted in the direction of linear movement of the moving body, the magnetic flux density detected by the magnetic detection element changes. Therefore, the displacement sensor cannot accurately detect the displacement of the moving body.
[0004]
Also, when a plurality of magnetic detecting elements are used, if the detecting portion of the magnetic detecting element is displaced from the central axis of the permanent magnet along the direction of linear movement of the moving body in a direction orthogonal to the central axis of the permanent magnet, magnetic detection is performed. The magnetic flux density detected by the element changes. Therefore, the displacement amount of the moving body cannot be detected with high accuracy.
[0005]
Also, when a plurality of magnetic detecting elements are used, if the distance between the detecting units of the magnetic detecting elements is far from each other in the linear moving direction of the moving body, a difference occurs in the magnetic flux density detected by each detecting unit, and the displacement amount of the moving body Cannot be detected with high accuracy.
An object of the present invention is to provide a displacement sensor that detects a displacement of a moving body in a linear movement direction with high accuracy.
[0006]
[Means for Solving the Problems]
According to the displacement sensor according to the first aspect of the present invention, the distance between the inner bottom of the housing and the mounting portion is L 1 , the distance between the inner bottom of the housing and the magnetic detection element is L 2 , and the linear expansion coefficient of the housing is α. 1, the linear expansion coefficient of the protruding member and alpha 2, is L 1 / L 2 = α 2 / α 1. Even if the housing and the projecting member expand or contract due to a change in the ambient temperature, the distance in the linear movement direction of the moving body formed between the mounting portion of the housing and the magnetic detection element in a state where the moving body is stationary is It becomes almost constant. Therefore, even when the ambient temperature changes and the housing and the protruding member expand or contract, the displacement amount of the moving body can be detected with high accuracy.
According to the displacement amount sensor according to the second aspect of the present invention, at least one of the housing and the protruding member can be easily formed of resin.
[0007]
According to the displacement sensor according to the third or fourth aspect of the present invention, the plurality of magnetic detecting elements are provided, and the central axis of the permanent magnet along the direction of linear movement of the moving body is the detecting surface of the detecting section of the plurality of magnetic detecting elements. Penetrates the center of the Since the magnetic flux density detected by the magnetic detection element does not vary in a direction orthogonal to the central axis of the permanent magnet, the displacement of the moving body can be detected with high accuracy.
[0008]
According to the displacement amount sensor according to claim 5 or 6 of the present invention, two of the plurality of magnetic detection elements are arranged such that the surfaces of the package on the thinner side between the detection surface of the detection unit and the surface of the package are connected to each other. Is in contact. By contacting the surfaces of the package on the thinner side, the distance between the detectors in the direction of linear movement of the moving body can be reduced as much as possible. Since the variation of the magnetic flux density detected by the detection unit can be reduced, the displacement amount of the moving body can be detected with high accuracy.
Furthermore, since the terminals of the two magnetic sensing elements that are in contact with the surfaces of the package on the thinner side are drawn out in a direction away from the package, it is easy to wire leads or the like to the terminals. is there.
[0009]
According to the displacement amount sensor according to claim 7 of the present invention, the terminals of the magnetic detecting element are drawn out of the package in the opposite direction by 180 °. Therefore, it is easy to wire a lead wire or the like to the terminal.
According to the displacement amount sensor according to claim 8 of the present invention, the magnetic flux density of the cylindrical hole decreases in one of the linear movement directions. When the position of the magnetic detection element in the linear movement direction in the cylindrical hole changes, the magnetic flux density detected by the magnetic detection element changes, so that the relative displacement of the magnetic detection element with respect to the permanent magnet in the linear movement direction can be detected. Therefore, when one of the permanent magnet and the magnetic detection element linearly moves with the moving body, the displacement amount of the moving body in the linear moving direction can be detected.
[0010]
Furthermore, since the permanent magnet is magnetized in the linear movement direction, the magnetic detection element detects even if the permanent magnet rotates relative to the magnetic detection element about the center axis of the cylindrical hole along the linear movement direction. The resulting magnetic flux density does not change. Therefore, it is possible to detect the displacement amount of the moving body that moves linearly while rotating. Further, there is no need for a rotation prevention mechanism for preventing the rotation of the moving body, which is necessary for detecting the displacement amount of the moving body that does not originally rotate in the linear movement direction with high accuracy. Since the number of parts is reduced, the structure of the displacement sensor is simplified. Further, wear of the moving body due to sliding with the rotation preventing mechanism can be prevented.
Further, since the permanent magnet used for the displacement sensor can be formed by one permanent magnet by cutting, molding, or the like, the number of components is reduced, and the assembly of the displacement sensor is easy.
According to the displacement sensor according to the ninth aspect of the present invention, when the permanent magnet is formed by cutting, the permanent magnet can be cut straight, so that the processing of the permanent magnet is easy.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example showing an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a displacement sensor according to an embodiment of the present invention. The displacement amount sensor 10 is installed in, for example, an EGR (Exhaust Gas Recirculation) valve of an automobile. By attaching a permanent magnet 50 described later of the present sensor to a shaft of an EGR valve that changes the amount of exhaust gas circulation (hereinafter, “an EGR valve shaft” is referred to as a moving body), and moving the permanent magnet 50 together with the moving body, the exhaust gas is reduced. , I.e., the amount of displacement of the moving body in the linear movement direction.
[0012]
The housing 12 of the displacement sensor 10 has a bottomed cylindrical shape made of resin. The housing 12 is fixed to a valve body of an EGR valve (hereinafter, a “valve body of the EGR valve” is referred to as a support member) or the like by a mounting portion 14 formed on an outer peripheral side of a cylindrical portion 13 of the housing 12. The mounting surface 15 of the mounting portion 14 is in contact with the support member.
[0013]
The columnar member 20, which is a protruding member, is made of resin, protrudes from the inner bottom 16 of the housing 12 toward the permanent magnet 50, and is fixed to the inner bottom 16 of the housing 12. The Hall IC 30 serving as a magnetic detection element is insert-molded on the tip end side of the columnar member 20. A terminal 19 for extracting a detection signal of the Hall IC 30 is insert-molded in the connector section 18 of the housing 12.
[0014]
As shown in FIG. 2, the Hall IC 30 serving as a magnetic detection element has a resin package 32, a detection unit 34 using a Hall element for detecting a magnetic flux density, and a terminal 36. The terminal 36 has a terminal 37 for supplying power to the detection unit 34 and a terminal 38 for extracting a detection signal from the detection unit 34. Further, the Hall IC 30 has a control circuit for controlling the detection signal of the detection unit 34 in the package 32.
[0015]
As shown in FIG. 3, the two Hall ICs 30 are in contact with each other on the thinner side formed between the detection surface 35 of the detection unit 34 and the surface of the package 32. The terminals 36 are drawn out of the package 32 in the opposite direction by 180 ° so as to be separated from each other. The two Hall ICs 30 are held in the columnar member 20 so that the detection surface 35 of the detection unit 34 is orthogonal to the central axis 110 of the permanent magnet 50 along the moving direction of the moving body.
[0016]
As shown in FIG. 1, the movable member 40 that moves linearly with the moving body has a cover 42 made of resin and a permanent magnet 50 insert-molded on the cover 42. The movable member 40 can reciprocate within the cylindrical portion 13 of the housing 12 in a linear movement direction indicated by arrows A and B in FIG. Since the movable member 40 is coupled or in contact with the end of the moving body, the movable member 40 moves linearly with the moving body.
The permanent magnet 50 has a through hole 100 as a cylindrical hole in the directions of arrows A and B that move linearly with the moving body. The columnar member 20 in which the Hall IC 30 is insert-molded can linearly move the through hole 100 relative to the permanent magnet 50.
[0017]
As shown in FIG. 4A, the inner peripheral surface 51 of the permanent magnet 50 forming the through hole 100 has substantially the same diameter in the direction of linear movement. The diameter of the outer peripheral surface 52 of the permanent magnet 50 decreases linearly in the direction of arrow A, which is one of the linear movement directions. Therefore, the thickness of the permanent magnet 50 in the radial direction orthogonal to the center axis 110 of the through hole 100 along the linear movement direction of the permanent magnet 50 decreases linearly in the direction of arrow A. In other words, the permanent magnet 50 is formed in a truncated cone shape, and has a cylindrical through hole 100 that penetrates in the direction of the central axis 110. That is, the cross section of the permanent magnet 50 orthogonal to the central axis 110 is annular, and the cross-sectional area decreases in the direction of arrow A. As shown in FIG. 4B, the permanent magnet 50 is magnetized in one direction of the linear movement from the thicker side to the thinner side. As shown in FIG. 5, the magnetic flux density in the through hole 100 is the largest on the central axis 110, and decreases as the distance from the central axis 110 increases.
The magnetic plate 60 is fixed to the end face 55 on the side where the thickness of the permanent magnet 30 is thicker by bonding or the like. The magnetic flux emitted from the end face 55 passes through the magnetic plate 60 and passes through the detection surface 35 of the detection unit 34 of the Hall IC 30 almost vertically.
[0018]
When the ambient temperature of the displacement sensor 10 changes, the housing 12 and the columnar member 20 expand or contract. Here, the linear expansion coefficient of the housing 12 shown in FIG. 6 is α 1 , and the linear expansion coefficient of the columnar member 20 is α 2 . In the linear moving direction of the moving body, the distance between the inner bottom 16 of the housing 12 and the mounting surface 15 at the temperature T is L 1 , and the distance between the inner bottom 16 of the housing 12 and the center of the two Hall ICs 30 is L 2. , the temperature from the temperature T is to [Delta] L 2 the elongation amount of L 2 portion of the columnar member 20 when [Delta] L 1 the elongation amount of L 1 portion of the housing 12, the temperature from the temperature T rises [Delta] T at the time of rise [Delta] T. ΔL 1 = L 1 × α 1 × ΔT and ΔL 2 = L 2 × α 2 × ΔT. Here, the center of the two Hall ICs 30 means an intermediate point between the two detection units 34.
[0019]
In order to keep the distance between the mounting surface 15 and the center of the two magnetic sensing elements 30 constant even if the housing 12 and the columnar member 20 expand or contract, the following expression (1) may be satisfied.
Figure 2004184364
That is, the ratio of the distance L 1 and the distance L 2 is, it is sufficient that the reciprocal of the ratio of the linear expansion coefficient alpha 2 of the linear expansion coefficient alpha 1 and the columnar member 20 of the housing 12. By satisfying Expression (1), the distance between the mounting surface 15 and the centers of the two Hall ICs 30 does not change even when the ambient temperature changes. That is, the position of the Hall IC 30 does not change with respect to the moving body at the same position. Even if the ambient temperature changes and the housing 12 and the columnar member 20 expand or contract, the magnetic flux density detected by the Hall IC 30 with respect to the moving body at the same position does not change, so that the displacement amount of the moving body can be detected with high accuracy.
[0020]
Since the two Hall ICs 30 are installed in the columnar member 20 so that the center axis 110 of the permanent magnet 50 passes through the center of the detection surface 35 of the detection unit 34, the magnetic flux density detected by the detection unit 34 Does not vary in a direction perpendicular to the central axis 110. Therefore, the displacement amount of the moving body can be detected with high accuracy.
[0021]
Further, the two Hall ICs 30 are in contact with each other on the thinner side formed between the detection surface 35 of the detection unit 34 and the surface of the package 32. Therefore, the distance between the two detectors 34 formed in the direction of the central axis 110 of the permanent magnet 50 can be reduced as much as possible. Since the magnetic flux densities detected by the two detection units 34 do not vary in the direction of the central axis 110, the displacement amount of the moving body can be detected with high accuracy.
[0022]
According to the present invention, the positions of the two holes 1 </ b> C <b> 30 may be shifted from the central axis 110 as long as Expression (1) is satisfied. In addition, according to the present invention, if Expression (1) is satisfied, the thinner side and the thicker side formed between the detection surface 35 of the detection unit 34 and the surface of the package 32, or The surfaces on the thick side may be in contact with each other.
[0023]
If the mounting surface 15 and the Hall IC 30 are at the same position in the direction of the central axis 110 of the permanent magnet 50, the housing 12 and the columnar member 20 can be integrally formed of the same resin material. In this embodiment, the housing 12 and the columnar member 20 are formed of a resin material, but may be formed of another non-magnetic material, for example, a ceramic.
In the present embodiment, the terminals 36 of the two Hall ICs 30 are installed in the columnar member 20 so as to be pulled out from the package 32 in the opposite direction by 180 °. Wiring is easy without interference. If the terminals 36 of the two Hall ICs 30 are pulled out of the package 32 in a direction away from each other, the direction in which the terminals 36 are separated is not limited to 180 °. Good.
[0024]
In this embodiment, the Hall IC 30 that holds the detection unit 34 and a control circuit (not shown) that controls the detection signal of the detection unit 34 in the package 32 is used as the magnetic detection element described in the claims. On the other hand, the detection unit 34 may be separated from the control circuit, and only the detection unit 34 may be insert-molded on the columnar member 20. An MRE element or a magnetoresistive element may be used as the magnetic detection element. The number of Hall ICs 30 is not limited to two, but may be one or three or more.
[0025]
In this embodiment, the permanent magnet 50 is magnetized in the direction of linear movement from the thicker side to the thinner side of the permanent magnet 50. On the other hand, the permanent magnet 50 may be magnetized in the direction of linear movement from the thinner side to the thicker side of the permanent magnet 50. In this case, the relationship between the displacement amount of the moving body and the magnetic flux density is reversed.
[0026]
In the present embodiment, the permanent magnet 50 is formed in a cylindrical shape, but any shape can be used for the permanent magnet as long as the magnetic flux density detected by the Hall IC 30 changes due to the moving body moving in a linear direction. It is.
In the present embodiment, the permanent magnet moves linearly with the moving body, and the Hall IC 30 as the magnetic detection element is stationary. On the other hand, a configuration in which the Hall IC 30 moves linearly with the moving object and the permanent magnet is stationary is also possible.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a displacement sensor according to an embodiment of the present invention.
FIG. 2A is a front view showing a Hall IC of the present embodiment, and FIG. 2B is a view in the direction of arrow B in FIG.
FIG. 3 is an explanatory diagram illustrating a contact state of two Hall ICs according to the present embodiment.
FIG. 4A is a cross-sectional view illustrating a permanent magnet of the displacement sensor according to the present embodiment, and FIG. 4B is an explanatory diagram illustrating a magnetization direction of the permanent magnet.
FIG. 5 is a characteristic diagram showing a relationship between a distance of a Hall IC from a magnet axis and a rate of change in magnetic flux density.
FIG. 6A is an explanatory view showing expansion of a housing, and FIG. 6B is an explanatory view showing expansion of a columnar member.
[Explanation of symbols]
10 Displacement sensor 12 Housing 14 Mounting part 15 Mounting surface 20 Columnar member (projecting member)
30 Hall IC (magnetic detection element)
32 Package 34 Detecting unit 35 Detecting surface 36 Terminal 50 Permanent magnet 51 Inner peripheral surface 52 Outer peripheral surface 100 Through hole (cylindrical hole)
110 center axis

Claims (10)

磁気検出素子および永久磁石を備え、前記磁気検出素子または前記永久磁石の一方は支持部材に取り付けられ、前記磁気検出素子または前記永久磁石の他方が移動体とともに直線移動することにより、前記磁気検出素子が前記移動体の直線移動方向の変位量を検出する変位量センサであって、
有底の筒部を有し、前記筒部の外周側に形成された取付部により前記移動体または前記支持部材に取り付けられているハウジングと、
前記筒部の内側底部から突出し、前記磁気検出素子を保持している突出部材とを備え、
前記移動体の直線移動方向において、前記ハウジングの前記内側底部と前記取付部との距離をＬ１、前記ハウジングの前記内側底部と前記磁気検出素子との距離をＬ２、前記ハウジングの線膨張係数をα１、前記突出部材の線膨張係数をα２とすると、Ｌ１／Ｌ２＝α２／α１であることを特徴とする変位量センサ。A magnetic detection element and a permanent magnet, wherein one of the magnetic detection element or the permanent magnet is attached to a support member, and the other of the magnetic detection element or the permanent magnet linearly moves together with a moving body, so that the magnetic detection element Is a displacement amount sensor for detecting the displacement amount of the moving body in the linear movement direction,
A housing having a bottomed cylinder portion, and a housing attached to the moving body or the support member by an attachment portion formed on an outer peripheral side of the cylinder portion;
A projecting member projecting from the inner bottom of the cylindrical portion and holding the magnetic detection element,
In the direction of linear movement of the moving body, the distance between the inner bottom portion of the housing and the mounting portion is L 1 , the distance between the inner bottom portion of the housing and the magnetic sensing element is L 2 , the linear expansion coefficient of the housing the alpha 1, displacement sensors, wherein the the linear expansion coefficient of the protruding member and alpha 2, is L 1 / L 2 = α 2 / α 1. 前記ハウジングおよび前記突出部材の少なくとも一方は樹脂であることを特徴とする請求項１記載の変位量センサ。The displacement sensor according to claim 1, wherein at least one of the housing and the protruding member is made of resin. 前記磁気検出素子は複数であり、前記移動体の直線移動方向に沿った前記永久磁石の中心軸は前記複数の磁気検出素子の検出部の検出面の中心を貫通していることを特徴とする請求項１または２記載の変位量センサ。A plurality of the magnetic detection elements are provided, and a central axis of the permanent magnet along a direction of linear movement of the moving body passes through a center of a detection surface of a detection unit of the plurality of magnetic detection elements. The displacement sensor according to claim 1. 磁気検出素子および永久磁石を備え、前記磁気検出素子または前記永久磁石の一方は支持部材に取り付けられ、前記磁気検出素子または前記永久磁石の他方が移動体とともに直線移動することにより、前記磁気検出素子が前記移動体の直線移動方向の変位量を検出する変位量センサであって、
前記磁気検出素子は複数であり、前記移動体の直線移動方向に沿った前記永久磁石の中心軸は前記複数の磁気検出素子の検出部の検出面の中心を貫通していることを特徴とする変位量センサ。A magnetic detection element and a permanent magnet, wherein one of the magnetic detection element or the permanent magnet is attached to a support member, and the other of the magnetic detection element or the permanent magnet linearly moves together with a moving body, so that the magnetic detection element Is a displacement amount sensor for detecting the displacement amount of the moving body in the linear movement direction,
A plurality of the magnetic detecting elements are provided, and a central axis of the permanent magnet along a linear moving direction of the moving body passes through a center of a detecting surface of a detecting unit of the plurality of magnetic detecting elements. Displacement sensor. 前記磁気検出素子は、検出部と、前記検出部を収容するパッケージと、前記検出部と電気的に接続している端子とを有し、複数の前記磁気検出素子のうち２個は、前記検出部の検出面と前記パッケージの表面との間の肉厚が薄い側の前記パッケージの面同士を接触し、前記２個の磁気検出素子の前記端子は前記パッケージから互いに離れる方向に引き出されていることを特徴とする請求項１から４のいずれか一項記載の変位量センサ。The magnetic detection element has a detection unit, a package accommodating the detection unit, and a terminal electrically connected to the detection unit. Two of the plurality of magnetic detection elements detect the magnetic field. The surface of the package on the thinner side between the detection surface of the portion and the surface of the package is in contact with each other, and the terminals of the two magnetic sensing elements are drawn out of the package in a direction away from each other. The displacement sensor according to any one of claims 1 to 4, wherein: 磁気検出素子および永久磁石を備え、前記磁気検出素子または前記永久磁石の一方は支持部材に取り付けられ、前記磁気検出素子または前記永久磁石の他方が移動体とともに直線移動することにより、前記磁気検出素子が前記移動体の直線移動方向の変位量を検出する変位量センサであって、
前記磁気検出素子は、検出部と、前記検出部を収容するパッケージと、前記検出部と電気的に接続している端子とを有し、複数の前記磁気検出素子のうち２個は、前記検出部の検出面と前記パッケージの表面との間の肉厚が薄い側の前記パッケージの面同士を接触し、前記２個の磁気検出素子の前記端子は前記パッケージから互いに離れる方向に引き出されていることを特徴とする変位量センサ。A magnetic detection element and a permanent magnet, wherein one of the magnetic detection element or the permanent magnet is attached to a support member, and the other of the magnetic detection element or the permanent magnet linearly moves together with a moving body, so that the magnetic detection element Is a displacement amount sensor for detecting the displacement amount of the moving body in the linear movement direction,
The magnetic detection element includes a detection unit, a package that houses the detection unit, and a terminal that is electrically connected to the detection unit. The surface of the package on the thinner side between the detection surface of the portion and the surface of the package is in contact with each other, and the terminals of the two magnetic sensing elements are drawn out of the package in a direction away from each other. Displacement amount sensor characterized by the above-mentioned. 前記２個の磁気検出素子の前記端子は、前記パッケージから１８０°反対方向に引き出されていることを特徴とする請求項５または６記載の変位量センサ。7. The displacement sensor according to claim 5, wherein the terminals of the two magnetic detection elements are pulled out from the package in the opposite direction by 180 degrees. 前記永久磁石は、前記移動体が直線移動する方向の少なくとも一方が開口し、前記永久磁石に対し直線移動方向に相対的に前記磁気検出素子が往復移動可能な筒孔を有し、直線移動方向に沿った前記筒孔の中心軸と直交する径方向の前記永久磁石の厚さは直線移動方向の一方に向けて減少し、前記永久磁石は直線移動方向に着磁されていることを特徴とする請求項１から７のいずれか一項記載の変位量センサ。The permanent magnet has an opening in at least one of the directions in which the moving body moves linearly, and has a cylindrical hole in which the magnetic detection element can reciprocate relatively to the permanent magnet in the direction of linear movement. The thickness of the permanent magnet in the radial direction orthogonal to the center axis of the cylindrical hole along the direction decreases in one of the linear movement directions, and the permanent magnet is magnetized in the linear movement direction. The displacement sensor according to any one of claims 1 to 7. 前記筒孔を形成する前記永久磁石の内周面の径はほぼ同一であり、前記永久磁石の外周面の径は直線移動方向の一方に向けて減少していることを特徴とする請求項８記載の変位量センサ。9. The diameter of the inner peripheral surface of the permanent magnet forming the cylindrical hole is substantially the same, and the diameter of the outer peripheral surface of the permanent magnet decreases in one of the linear movement directions. The displacement sensor described in the above. 前記磁気検出素子はホールＩＣであることを特徴とする請求項１から９のいずれか一項記載の変位量センサ。The displacement sensor according to claim 1, wherein the magnetic detection element is a Hall IC.
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Cited By (5)

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JP2007303891A (en) * 2006-05-09 2007-11-22 Denso Corp Magnetometric sensor
JP2008008756A (en) * 2006-06-29 2008-01-17 Aisan Ind Co Ltd Rotation angle detection apparatus
US7859252B2 (en) 2006-06-29 2010-12-28 Aisan Kogyo Kabushiki Kaisha Rotational angle detecting devices
JP2013500484A (en) * 2009-07-28 2013-01-07 マーレ インターナショナル ゲゼルシャフト ミット ベシュレンクテル ハフツング Position sensor and linear actuator
CN111351899A (en) * 2020-03-31 2020-06-30 山东大学 Monitoring system and method for offshore submarine landslide physical model test

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007303891A (en) * 2006-05-09 2007-11-22 Denso Corp Magnetometric sensor
JP4577263B2 (en) * 2006-05-09 2010-11-10 株式会社デンソー Magnetic sensor
JP2008008756A (en) * 2006-06-29 2008-01-17 Aisan Ind Co Ltd Rotation angle detection apparatus
US7859252B2 (en) 2006-06-29 2010-12-28 Aisan Kogyo Kabushiki Kaisha Rotational angle detecting devices
JP2013500484A (en) * 2009-07-28 2013-01-07 マーレ インターナショナル ゲゼルシャフト ミット ベシュレンクテル ハフツング Position sensor and linear actuator
US9057628B2 (en) 2009-07-28 2015-06-16 Mahle International Gmbh Position sensor and linear actuator
CN111351899A (en) * 2020-03-31 2020-06-30 山东大学 Monitoring system and method for offshore submarine landslide physical model test

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