JP2004361119A

JP2004361119A - Rotational angle detector

Info

Publication number: JP2004361119A
Application number: JP2003156815A
Authority: JP
Inventors: Kenji Takeda; 武田　　憲司; Shigetoshi Fukaya; 深谷　　繁利; Akira Sano; 亮佐野; Yuji Kajita; 祐司梶田
Original assignee: Denso Corp; Nippon Soken Inc
Current assignee: Denso Corp; Soken Inc
Priority date: 2003-06-02
Filing date: 2003-06-02
Publication date: 2004-12-24

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotational angle detector with no detection error due to changes in the direction of a magnetic flux to a magnetic detection chip. <P>SOLUTION: Polarizing directions of a magnetic flux imparting magnet 11 and a magnetic flux attracting magnet 12 in the direction of the rotation axis are opposite. Because of this, even when the magnets are located a distance L apart from a magnetic detection chip 3 in the direction of the rotational axis, a magnetic flux a1 can be applied to the magnetic detection chip 3. As a result, the magnetic detection chip 3 which is located at a position where a shielding member is placed in-between can detect a rotational angle of a magnetic flux generating means 5. By providing the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 in parallel with sufficient length, even if there exists an assembly deviation between the magnetic flux generating means 5 and the magnetic detection chip 3, a magnetic flux corresponding to a rotational angle can be applied to the magnetic detection chip 3, thereby preventing errors. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、２つの部材（例えば、回転部材と非回転部材）の相対回転角度を非接触で検出する回転角度検出装置に関する。
【０００２】
【従来の技術】
（第１従来技術）
２つの部材の相対回転角度を非接触で検出する従来の回転角度検出装置の概略構造を図１０（ａ）、（ｂ）を参照して説明する。
回転角度検出装置は、回転軸上に配置された磁気検出素子Ｊ１（例えば、磁気抵抗素子：ＭＲＥ）と、回転軸方向の磁気検出素子Ｊ１が配置された側に磁束の発生部Ｊ２が向けられて磁気検出素子Ｊ１に磁束を与える磁束付与磁石Ｊ３（磁束付与手段の一例）と、回転軸方向の磁気検出素子Ｊ１が配置された側に磁束の吸引部Ｊ４が向けられて磁束付与磁石Ｊ３から放出された磁束を吸引する磁束吸引磁石Ｊ５（磁束吸引手段の一例）とを備える。なお、磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５で磁束発生手段Ｊ６が構成される（例えば、特許文献１参照）。
【０００３】
ここで、磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５は、磁気検出素子Ｊ１に対して回転軸方向に距離Ｌを隔てて配置されるとともに｛図１０（ａ）参照｝、回転軸方向から見て磁気検出素子Ｊ１の周囲に距離を隔てて対向配置されたものである｛図１０（ｂ）参照｝。
そして、磁束発生手段Ｊ６（磁束付与磁石Ｊ３および磁束吸引磁石Ｊ５）と、磁気検出素子Ｊ１との相対回転角度が変化すると、磁気検出素子Ｊ１の磁気検出面と直交する方向の磁束密度が変化して磁気検出素子Ｊ１の出力が変化する（図１１参照）。
【０００４】
ここで、ＭＲＥよりなる磁気検出素子Ｊ１の出力は、図１１に示すようにサインカーブを描く。近年では検出精度を高める目的で、検出範囲のサインカーブの傾きを極力直線的にして、しかも直線化した検出範囲を広げる工夫が種々されている。
しかし、実際に直線化した検出範囲を広げるのは困難であり、現実的にはサインカーブを直線化した検出範囲は６０°（サインカーブの出力０を基準とした±３０°）が限度である。
【０００５】
（第２従来技術）
そこで、ＭＲＥよりなる磁気検出素子Ｊ１を２つ設けて検出精度の向上と検出範囲の拡大を図る技術が提案されている。
この技術は、図１２（ａ）に示すように、磁気検出面が所定の角度（例えば、オフセット角が４５°、電気位相角が９０°）を隔てるように、２つの磁気検出素子Ｊ１を配置するものである。なお、この２つの磁気検出素子Ｊ１は、図１３に示すように磁気検出チップＪ７として搭載されるものである。
そして、磁束発生手段Ｊ６（磁束付与磁石Ｊ３および磁束吸引磁石Ｊ５）と、磁気検出チップＪ７（２つの磁気検出素子Ｊ２）との相対回転角度が変化すると、２つの磁気検出素子Ｊ１の出力は、図１２（ｂ）に示すように変化する。
【０００６】
２つの出力信号は、図１２（ｂ）に示すように、９０°の電気位相差があるため、２つの磁気検出素子Ｊ１の出力は、それぞれｓｉｎ２αとｃｏｓ２αに比例する（α＝回転角度）。
これら２つの信号は、数学的に次の式で表される。
一方の信号Ｘ（α，Ｔ）＝Ｘ０（Ｔ）ｓｉｎ２α
他方の信号Ｙ（α，Ｔ）＝Ｙ０（Ｔ）ｃｏｓ２α
【０００７】
２つの信号の振幅（Ｘ０、Ｙ０）が同一であると仮定した場合（Ｘ０＝Ｙ０）、未知の角度αは次の式によって求められる。
α＝（１／２）ａｒｃｔａｎ（Ｘ／Ｙ）
このように、磁気検出素子Ｊ１を２つ設けることで、上述した第１従来技術のように磁気検出素子Ｊ１の出力を直線化することなく、検出精度の向上と検出範囲の拡大を図ることができる（例えば、非特許文献１参照）。
【０００８】
【特許文献１】
特開２００１−３０４８０５公報
【非特許文献１】
クラウス・ディートマイヤー（ＫｌａｕｓＤｉｅｔｍａｙｅｒ）、外１名，「ＫＭＺ４１およびＵＺＺ９００１を使用した非接触角度測定」，アプリケーション・ノートＡＮ００００４，日本フィリップス株式会社，２０００年１月１７日
【０００９】
【発明が解決しようとする課題】
磁束発生手段Ｊ６（磁束付与磁石Ｊ３および磁束吸引磁石Ｊ５）と、磁気検出チップＪ７（２つの磁気検出素子Ｊ１）とが相対回転した場合、その回転角度と同じように、磁気検出チップＪ７に対する磁束の向きが変わる必要がある。
このことは、組付け上の誤差等によって、磁束発生手段Ｊ６（磁束付与磁石Ｊ３および磁束吸引磁石Ｊ５）の回転中心と、磁気検出チップＪ７（２つの磁気検出素子Ｊ１）の中心にズレが生じるような場合であっても成り立つように考慮されるべきである。
【００１０】
そこで、非特許文献１には、図１３に示すように、磁気検出チップＪ７が取り付けられるべき基板Ｊ８の上に嵩上げ部品Ｊ９を固定し、その嵩上げ部品Ｊ９の上に磁気検出チップＪ７を固定して、磁気検出チップＪ７を磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５の内側に配置して、磁気検出チップＪ７が取り付けられる近傍の空間の磁束の向きを均一化する技術が開示されている。
【００１１】
しかし、図１３に示すように、磁気検出チップＪ７を磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５の内側に配置させる技術は、本来であれば基板Ｊ８の上に直接ハンダ付け等で磁気検出チップＪ７を設置できる利点を放棄するものであり、上述したような嵩上げ部品Ｊ９を必要とする。このことは、部品点数の増大を招くだけでなく、基板Ｊ８と磁気検出チップＪ７の配線が必要になり、配線の複雑化も招いてしまう。
【００１２】
また、磁気検出チップＪ７を磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５の内側に配置させる必要があるため、磁束発生手段Ｊ６（磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５）から回転軸方向に距離を隔てて磁気検出チップＪ７を配置することができない。このため、使用用途が限られてしまう。即ち、磁束発生手段Ｊ６と磁気検出チップＪ７を軸方向に離した回転角度検出装置（例えば、磁束発生手段Ｊ６と磁気検出チップＪ７の軸方向の間に隔壁等を配置するスロットルバルブの回転角度検出装置等）に適用することはできない。
【００１３】
一方、図１０（ａ）に示されるように、磁束付与磁石Ｊ３は回転軸方向の磁気検出素子Ｊ１が配置された側に磁束の発生部Ｊ２が向けられ、磁束吸引磁石Ｊ５は回転軸方向の磁気検出素子Ｊ１が配置された側に磁束の吸引部Ｊ４が向けられる構成により、磁束発生手段Ｊ６（磁束付与磁石Ｊ３と磁束吸引磁石Ｊ５）から回転軸方向に距離Ｌを隔てて配置される磁気検出素子Ｊ１の磁気検出面（回転軸の直交方向に向けられた磁気検出面）に磁束ａ１ ’を与える構成を採用している。
しかし、磁気検出素子Ｊ１とは異なった側｛図１０（ａ）では下側｝で発生する磁束ａ２ ’はなんら利用されずに無駄になっている。
【００１４】
【発明の目的】
本発明は上記の事情に鑑みてなされたものであり、次の３つの目的を有する。
第１の目的は、磁束発生手段（磁束付与手段と磁束吸引手段）と磁気検出チップ（２つの磁気検出素子）とを回転軸方向に距離を隔てて配置することができ、且つ、磁束発生手段と磁気検出チップとが、組付け上の誤差等によって回転軸の直交方向にズレるような場合であっても、磁束発生手段と磁気検出チップとが相対回転した場合に、その回転角度と同じように、磁気検出チップに対する磁束の向きが変わる検出誤差の発生のない回転角度検出装置の提供にある。
【００１５】
第２の目的は、磁束発生手段（磁束付与磁石と磁束吸引磁石）と磁気検出素子とを回転軸方向に距離を隔てて配置することができ、且つ、磁束付与磁石と磁束吸引磁石において磁気検出素子とは異なった側で発生する磁束の無駄を抑えて、磁気検出素子に与えられる磁束を強める、あるいは磁束付与磁石と磁束吸引磁石の小型軽量化を図ることのできる回転角度検出装置の提供にある。
【００１６】
第３の目的は、磁束発生手段（磁束付与磁石と磁束吸引磁石）と磁気検出チップ（２つの磁気検出素子）とを回転軸方向に距離を隔てて配置することができ、且つ、磁束付与磁石と磁束吸引磁石において磁気検出チップとは異なった側で発生する磁束の無駄を抑えて、磁気検出チップに与えられる磁束を強める、あるいは磁束付与磁石と磁束吸引磁石の小型軽量化を図ることのできる回転角度検出装置の提供にある。
【００１７】
【課題を解決するための手段】
〔請求項１の手段〕
請求項１の手段の磁束発生手段は、回転軸方向の磁気検出チップが配置された側に磁束の発生部が向けられた磁束付与手段と、回転軸方向の磁気検出チップが配置された側に磁束の吸引部が向けられた磁束吸引手段とを備える。
この構成を採用することにより、磁束発生手段（磁束付与手段と磁束吸引手段）と磁気検出チップとを回転軸方向に距離を隔てて配置しても、２つの磁気検出素子に磁束を与えることができる。
これによって、磁束発生手段と磁気検出チップとを回転軸方向に距離を隔てて配置した状態で、磁束発生手段と磁気検出チップの相対回転角度が変化すると、２つの磁気検出素子から相対回転角度の変化に応じた出力が発生する。即ち、磁束発生手段と磁気検出チップとを回転軸方向に距離を隔てて配置した状態で、相対回転角度の変化を検出できる。
【００１８】
さらに、磁束付与手段から磁気検出チップを介して磁束吸引手段に向かう磁束の流れ方向を、磁気検出チップの組付誤差範囲内において平行にする磁束平行化手段が設けられている。
これによって、磁束発生手段と磁気検出チップとが、組付け上の誤差によって回転軸の直交方向にズレるような場合であっても、磁束発生手段と磁気検出チップとが相対回転した場合、その回転角度と同じように、磁気検出チップに対する磁束の向きが変わる。このため、組付け上の誤差が生じても検出誤差の発生を防ぐことができる。
【００１９】
即ち、請求項１の回転角度検出装置は、磁束発生手段と磁気検出チップとを回転軸方向に距離を隔てて配置した状態で、磁束発生手段と磁気検出チップの相対回転角度の変化を２つの磁気検出素子の出力によって検出することができるとともに、磁束発生手段と磁気検出チップとに組付け上の誤差が生じても検出誤差の発生を防ぐことができる。
【００２０】
〔請求項２の手段〕
請求項２の手段を採用する回転角度検出装置は、磁束付与手段と磁束吸引手段を回転軸を隔てて平行配置して、この平行方向に沿う磁束付与手段と磁束吸引手段のそれぞれの長さを長くすることによって磁束平行化手段を設けたものである。
このように設けることによって、磁気検出チップの組付誤差の範囲内において磁束付与手段から磁束吸引手段に向かう磁束方向を平行化できる。
【００２１】
〔請求項３の手段〕
請求項３の手段を採用する回転角度検出装置は、磁束付与手段と磁束吸引手段を回転軸を中心とした略扇形形状にすることによって磁束平行化手段を設けたものである。
このように設けることによって、磁気検出チップの組付誤差の範囲内において磁束付与手段から磁束吸引手段に向かう磁束方向を平行化できる。
【００２２】
〔請求項４の手段〕
請求項４の手段を採用する回転角度検出装置は、磁束付与手段と磁束吸引手段をそれぞれ複数の直方体によって構成し、その複数の直方体を回転軸を中心として円弧状に配置することによって磁束平行化手段を設けたものである。
このように設けることによって、磁気検出チップの組付誤差の範囲内において磁束付与手段から磁束吸引手段に向かう磁束方向を平行化できる。
【００２３】
〔請求項５の手段〕
請求項５の手段を採用する回転角度検出装置の磁束付与手段と磁束吸引手段は、回転軸方向に着磁され、磁束付与手段と磁束吸引手段の着磁方向が逆方向の永久磁石である。
このように設けることによって、磁気検出チップに対して回転軸方向に距離を隔てて配置された永久磁石よりなる磁束付与手段と磁束吸引手段から、磁気検出チップにおける２つの磁気検出素子に磁束を与えることができる。
【００２４】
〔請求項６の手段〕
請求項６の手段を採用する回転角度検出装置は、永久磁石よりなる磁束付与手段と磁束吸引手段の磁気検出チップとは異なった側に磁性体製よりなるヨークを配置し、磁束付与手段と磁束吸引手段の磁気検出チップとは異なった側をヨークで磁気結合したものである。
このように設けることによって、永久磁石よりなる磁束付与手段と磁束吸引手段において磁気検出素子とは異なった側で発生する磁束の無駄を抑えることができ、結果的に磁気検出素子に与える磁束を強めることができる。あるいは、永久磁石よりなる磁束付与手段と磁束吸引手段の小型軽量化を図ることができる。
【００２５】
〔請求項７の手段〕
請求項７の手段を採用する回転角度検出装置は、回転軸方向の磁気検出素子が配置された側に磁束の発生部が向けられた磁束付与磁石と、回転軸方向の磁気検出素子が配置された側に磁束の吸引部が向けられた磁束吸引磁石とを備える。
この構成を採用することにより、磁束発生手段（磁束付与磁石と磁束吸引磁石）と磁気検出素子とを回転軸方向に距離を隔てて配置しても、磁気検出素子に磁束を与えることができる。
これによって、磁束発生手段と磁気検出素子を回転軸方向に距離を隔てて配置した状態で、磁束発生手段と磁気検出素子の相対回転角度が変化すると、磁気検出素子から相対回転角度の変化に応じた出力が発生する。即ち、磁束発生手段と磁気検出素子とを回転軸方向に距離を隔てて配置した状態で、相対回転角度の変化を検出できる。
【００２６】
さらに、請求項７の手段を採用する回転角度検出装置は、磁束付与磁石と磁束吸引磁石の磁気検出素子とは異なった側に磁性体製よりなるヨークを配置し、磁束付与磁石と磁束吸引磁石の磁気検出素子とは異なった側をヨークで磁気結合したものである。
このように設けることによって、磁束付与磁石と磁束吸引磁石において磁気検出素子とは異なった側で発生する磁束の無駄を抑えることができ、結果的に磁気検出素子に与える磁束を強めることができる。あるいは、磁束付与磁石と磁束吸引磁石の小型軽量化を図ることができる。
【００２７】
〔請求項８の手段〕
請求項８の手段を採用する回転角度検出装置は、回転軸方向の磁気検出チップが配置された側に磁束の発生部が向けられた磁束付与磁石と、回転軸方向の磁気検出チップが配置された側に磁束の吸引部が向けられた磁束吸引磁石とを備える。
この構成を採用することにより、磁束発生手段（磁束付与磁石と磁束吸引磁石）と磁気検出チップ（２つの磁気検出素子）とを回転軸方向に距離を隔てて配置しても、磁気検出チップにおける２つの磁気検出素子に磁束を与えることができる。
これによって、磁束発生手段と磁気検出チップとを回転軸方向に距離を隔てて配置した状態で、磁束発生手段と磁気検出チップの相対回転角度が変化すると、２つの磁気検出素子から相対回転角度の変化に応じた出力が発生する。即ち、磁束発生手段と磁気検出チップとを回転軸方向に距離を隔てて配置した状態で、相対回転角度の変化を検出できる。
【００２８】
さらに、請求項８の手段を採用する回転角度検出装置は、磁束付与磁石と磁束吸引磁石の磁気検出チップとは異なった側に磁性体製よりなるヨークを配置し、磁束付与磁石と磁束吸引磁石の磁気検出チップとは異なった側をヨークで磁気結合したものである。
このように設けることによって、磁束付与磁石と磁束吸引磁石において磁気検出チップとは異なった側で発生する磁束の無駄を抑えることができ、結果的に２つの磁気検出素子に与える磁束を強めることができる。あるいは、磁束付与磁石と磁束吸引磁石の小型軽量化を図ることができる。
【００２９】
【発明の実施の形態】
本発明の実施の形態を、３つの実施例と変形例を用いて説明する。
［第１実施例］
図１〜図４を用いて第１実施例を説明する。なお、図１（ａ）は回転軸方向に沿う回転角度検出装置の概略断面図であり、図１（ｂ）は回転軸方向から見た回転角度検出装置の概略図である。また、図２はスロットルバルブに組付けられた回転角度検出装置の断面図である。
【００３０】
まず、図２を参照して回転角度検出装置の基本構成を説明する。
この実施例に示す回転角度検出装置は、スロットルバルブ１の回転角度（開度）を検出するためのものであり、回路基板２（固定部材）に搭載された磁気検出チップ３と、ロータ４（回転部材）に固定された磁束発生手段５とを備える。
【００３１】
磁束発生手段５が配置される空間は、エンジンの吸気側あるいは大気と繋がっているため、排気ガスや水分といった回路基板２に搭載される電子部品に悪影響をおよぼすおそれのある物質が存在する。
そこで、磁気検出チップ３と磁束発生手段５とを、図１（ａ）に示すようにロータ４の回転軸方向に距離Ｌを隔てて配置するとともに、図２に示すように磁気検出チップ３と磁束発生手段５の回転軸方向の間に遮蔽部材６を配置して、磁気検出チップ３が配置される空間と、磁束発生手段５が配置される空間とを分離している。これによって、排気ガスや水分といった電子部品に悪影響をおよぼすおそれのある物質が、回路基板２が配置される空間に侵入しない。
【００３２】
磁気検出チップ３は、図３（ａ）に示されるように、磁気検出面が４５°（所定の角度の一例）を隔てて配置された２つの磁気抵抗素子７（磁気検出素子の一例）を搭載する電気部品であり、２つの磁気抵抗素子７の磁気検出面がロータ４の回転軸の直交方向に向くとともに、２つの磁気抵抗素子７の磁気検出面（磁気検出チップ３の中心Ｏ）がロータ４の回転中心Ｏ’と一致するように配置されるものである。
【００３３】
ロータ４は、スロットルバルブ１のシャフト８にネジ等の締結手段９によって固定されるヨーク１０と、このヨーク１０に固定された磁束発生手段５とで構成される。
この磁束発生手段５は、図１（ｂ）に示すように、回転軸方向から見て、磁気検出チップ３の両側に距離を隔てて対向配置される磁束付与磁石１１（磁束付与手段の一例）と磁束吸引磁石１２（磁束吸引手段の一例）の２つの磁石によって構成される。
【００３４】
磁束付与磁石１１は、図１（ａ）に示すように、回転軸方向の磁気検出チップ３が配置された側に磁束の発生部１１ａが向けられるものであり、具体的には磁気検出チップ３が配置された側にＮ極が向くように着磁された磁石である。
磁束吸引磁石１２は、回転軸方向の磁気検出チップ３が配置された側に磁束の吸引部１２ａが向けられるものであり、具体的には磁気検出チップ３が配置された側にＳ極が向くように着磁された磁石である。
【００３５】
このような磁束付与磁石１１と磁束吸引磁石１２を用いることにより、磁束発生手段５と磁気検出チップ３とを回転軸方向に距離Ｌを隔てて配置しても、図１（ａ）に示すように、磁気検出チップ３（２つの磁気抵抗素子７の磁気検出面）に磁束ａ１を与えることができる。
これによって、磁束発生手段５と磁気検出チップ３とが回転軸方向に距離Ｌを隔てて配置された状態であっても、磁束発生手段５と磁気検出チップ３の相対回転角度が変化すると、２つの磁気抵抗素子７から相対回転角度の変化に応じた出力が発生する。即ち、磁束発生手段５と磁気検出チップ３とを回転軸方向に距離Ｌを隔てて配置した状態で相対回転角度の変化を検出できる（第１の効果）。
【００３６】
具体的には、従来技術の項でも説明したように、２つの磁気抵抗素子７は、オフセット角が４５°、電気位相角が９０°を隔てるものであるため、ロータ４の回転に伴って磁束発生手段５（磁束付与磁石１１および磁束吸引磁石１２）が回転すると、２つの磁気抵抗素子７の出力は、図３（ｂ）に示すように変化する。
【００３７】
２つの出力信号は、図３（ｂ）に示すように、９０°の電気位相差があるため、２つの磁気抵抗素子７の出力は、それぞれｓｉｎ２αとｃｏｓ２αに比例する（α＝回転角度）。
これら２つの信号は、数学的に次の式で表される。
一方の信号Ｘ（α，Ｔ）＝Ｘ０（Ｔ）ｓｉｎ２α
他方の信号Ｙ（α，Ｔ）＝Ｙ０（Ｔ）ｃｏｓ２α
【００３８】
２つの信号の振幅（Ｘ０、Ｙ０）が同一であると仮定した場合（Ｘ０＝Ｙ０）、未知の角度αは次の式によって求められる。
α＝（１／２）ａｒｃｔａｎ（Ｘ／Ｙ）
このように、磁気抵抗素子７を２つ設けることで、検出精度の向上と検出範囲の拡大を図ることができる。
【００３９】
一方、ヨーク１０は鉄などの磁性体によって設けられるものであり、磁気検出チップ３が配置される側とは異なった側に配置されて、磁束付与磁石１１と磁束吸引磁石１２の磁気結合を行うものである。
このように設けることで、図１（ａ）に示すように、磁気検出チップ３が配置される側とは異なった側で発生する磁束ａ２は、ヨーク１０を介して効率的に流れる。これによって、磁束発生手段５における磁束の無駄が抑えられるため、結果的に磁気検出チップ３に与える磁束を強めることができる。あるいは、磁束付与磁石１１と磁束吸引磁石１２の小型軽量化を図ることができる（第２の効果）。
【００４０】
ここで、磁束発生手段５には、磁束付与磁石１１から磁気検出チップ３を介して磁束吸引磁石１２に向かう磁束の流れ方向を、磁気検出チップ３の組付誤差範囲内において平行にする磁束平行化手段が設けられている。
この実施例の磁束平行化手段は、図４（ａ）に示すように、磁束付与磁石１１と磁束吸引磁石１２を直方体の磁石で設け、回転軸を隔てて平行配置するとともに、この平行方向に沿う磁束付与磁石１１と磁束吸引磁石１２のそれぞれの長さＤを長く設けたものである。
【００４１】
このことを図４（ａ）、（ｂ）を参照して説明する。
図４（ａ）に示すように、磁気検出チップ３の中心Ｏは、回転中心Ｏ’と一致するように組付けられる。
しかし、現実的には、組付誤差等によって磁気検出チップ３の中心Ｏが、回転中心Ｏ’からズレる可能性がある。
【００４２】
図４（ａ）に示すように、磁気検出チップ３の中心Ｏは、回転中心Ｏ’と一致するように組付けられた場合に、磁気検出チップ３を通過する磁束の角度がθであった場合、図４（ｂ）に示すように、磁気検出チップ３の中心Ｏが、回転中心Ｏ’から組付誤差の範囲よりも大きくズレると、磁気検出チップ３を通過する磁束の角度がθ’となってしまう（θ≠θ’）。
【００４３】
しかるに、磁束付与磁石１１と磁束吸引磁石１２のそれぞれの長さＤを長く設けたことにより、図４（ｂ）中の丸Ａ（回転中心Ｏ’を中心とした円）内に示す範囲内（磁気検出チップ３の組付誤差範囲）は、磁束付与磁石１１から磁気検出チップ３を介して磁束吸引磁石１２に向かう磁束の流れ方向が平行になる。
このため、磁気検出チップ３の中心Ｏが、回転中心Ｏ’から所定の組付誤差の範囲内でズレても、磁気検出チップ３を通過する磁束の角度が変化しなくなる。即ち、磁気検出チップ３の中心Ｏと回転中心Ｏ’が組付け上の誤差の範囲内でズレるような場合であっても、磁束発生手段５と磁気検出チップ３とが相対回転した場合、ズレの無い場合と同じように、磁気検出チップ３に対する磁束の向きが変わる。このため、組付け上の誤差が生じても検出誤差の発生が防がれる（第３の効果）。
【００４４】
［第１実施例の効果］
本実施例の回転角度検出装置は、次の４つの効果を奏することができる。
（１）回転軸方向の磁気検出チップ３が配置された側に磁束の発生部１１ａが向くように磁束付与磁石１１を設けるとともに、回転軸方向の磁気検出チップ３が配置された側に磁束の吸引部１２ａが向くように磁束吸引磁石１２を設けることにより、磁束発生手段５と磁気検出チップ３とを回転軸方向に距離Ｌを隔てて配置しても、磁気検出チップ３（２つの磁気抵抗素子７の磁気検出面）に磁束を与えることができ、２つの磁気抵抗素子７の出力によって相対回転角度の変化を検出できる。
【００４５】
（２）磁気検出チップ３が配置される側とは異なった側において磁束付与磁石１１と磁束吸引磁石１２を磁性体製のヨーク１０で磁気結合したことにより、磁気検出チップ３が配置される側とは異なった側で発生する磁束の無駄を抑えることができる。これによって、結果的に磁気検出チップ３に与える磁束を強めることができる。あるいは、磁束付与磁石１１と磁束吸引磁石１２の小型軽量化を図ることができる。
【００４６】
（３）磁束付与磁石１１と磁束吸引磁石１２を直方体の磁石で設け、回転軸を隔てて平行配置するとともに、平行方向に向く磁束付与磁石１１と磁束吸引磁石１２のそれぞれの長さＤを長く設けたことにより、磁気検出チップ３の中心Ｏが回転中心Ｏ’から所定の組付誤差の範囲内でズレても、磁気検出チップ３を通過する磁束の角度が変化しなくなる。これによって、磁気検出チップ３の中心Ｏが回転中心Ｏ’から所定の組付誤差の範囲内でズレても、検出誤差の発生を防ぐことができる。
【００４７】
（４）磁束発生手段５と磁気検出チップ３とを回転軸方向に距離Ｌを隔てて配置した状態で、磁気検出チップ３の組付位置が所定の組付誤差の範囲内でズレても、検出誤差の発生を防ぐことができる。これによって、従来技術の項で示したような嵩上げ部品（図１３の符号Ｊ９参照）を廃止でき、磁気検出チップ３を直接回路基板２に搭載できる。このため、磁気検出チップ３を回路基板２の上に直接ハンダ付け等で設置でき、生産性が向上する。また、嵩上げ部材を用いないため、嵩上げ部品を用いることによる配線の複雑化も解消できる。
【００４８】
［第２実施例］
図５〜図７を用いて第２実施例を説明する。なお、この第２実施例以降における第１実施例と同一符号は、特に説明を加えない限り同一機能物を示すものである。
上記の第１実施例は、磁束付与磁石１１と磁束吸引磁石１２を直方体の磁石で設け、回転軸を隔てて平行配置し、平行方向に向く磁束付与磁石１１と磁束吸引磁石１２のそれぞれの長さＤを長く設けることで、磁気検出チップ３の組付誤差範囲内の磁束の流れ方向を平行にした例を示した。
【００４９】
これに対し、この第２実施例では、図５（ｂ）に示すように、磁束付与磁石１１と磁束吸引磁石１２を回転軸を中心とした略扇形形状に設けることで、磁気検出チップ３の組付誤差範囲内の磁束の流れ方向を平行にしたものである。
このことを具体的に説明する。
磁束付与磁石１１と磁束吸引磁石１２の形状は、回転軸方向の厚さα、内径寸法β、外径寸法γ、扇角度δで決定されるが、厚さα、内径寸法β、外径寸法γは、磁気検出チップ３に与える磁束の強さに影響を与えるが、磁束付与磁石１１から磁束吸引磁石１２に向かう磁束の流れ方向にあまり寄与しない。
【００５０】
扇角度δが適切でない場合の磁束の流れを図６（ａ）、（ｂ）に示す。図６（ａ）は扇角度δが適切範囲よりも小さい場合を示すものであり、図６（ｂ）は扇角度δが適切範囲よりも大きい場合を示すものである。
扇角度δが適切範囲よりも小さい場合、回転中心Ｏ’から離れるにつれて磁束の向きが外側に膨らむ。このため、回転中心Ｏ’における磁束の角度がθの場合、図６（ａ）に示すように、磁気検出チップ３の中心Ｏが回転中心Ｏ’から大きくズレると、磁気検出チップ３を通過する磁束の角度がθ’となり、θとθ’とに角度差が生じてしまう（θ≠θ’）。
【００５１】
逆に、扇角度δが適切範囲よりも大きい場合、回転中心Ｏ’から離れるにつれて磁束の向きが内側に凹む。このため、回転中心Ｏ’における磁束の角度がθの場合、図６（ｂ）に示すように、磁気検出チップ３の中心Ｏが回転中心Ｏ’から大きくズレると、磁気検出チップ３を通過する磁束の角度がθ’となり、θとθ’とに角度差が生じてしまう（θ≠θ’）。
【００５２】
本願発明者等は、磁束の向きが外側に膨む、内側に凹むというように傾向が逆になることから、最適な扇角度を含めた磁石形状が存在すると考え、種々の形状のシュミレーションや試作品で特性を求めた。
磁束発生手段５と磁気検出チップ３との回転軸方向の距離Ｌが３ｍｍ、磁気検出チップ３の中心Ｏの磁束発生手段５の回転中心Ｏ’に対する中心ズレがＸ方向（回転軸の直交方向の任意の線方向）に１．２ｍｍ、Ｙ方向（回転軸の直交方向で、且つＸ方向の直交方向）に１．２ｍｍと想定し、内径寸法β、外径寸法γ、扇角度δのそれぞれ１つを変化させて、上述した磁束角度θとθ’の角度差（θ−θ’）の変化を求めた。この角度差（θ−θ’）の変化を、図７（ａ）〜（ｃ）に示す。ここで、角度差（θ−θ’）は、回転角度検出装置の誤差となって現れる。
なお、図７（ａ）は内径寸法βを変化させた場合における角度差（θ−θ’）の変化量を示すグラフ、図７（ｂ）は外径寸法γを変化させた場合における角度差（θ−θ’）の変化量を示すグラフ、図７（ｃ）は扇角度δを変化させた場合における角度差（θ−θ’）の変化量を示すグラフである。
【００５３】
図７（ａ）、（ｂ）から読み取れるように、内径寸法βや外径寸法γを変化させても、角度差（θ−θ’）はあまり変化しない。
図７（ｃ）から読み取れるように、角度差（θ−θ’）が最も小さくなるのは、扇角度δが１１０°付近であり、１１０°から扇角度δが大きくなる、あるいは１１０°から扇角度δが小さくなるに従って、角度差（θ−θ’）が大きくなってしまう。
角度差（θ−θ’）が最も小さくなる扇角度δは、距離Ｌを３ｍｍ±０．５ｍｍの範囲で変化させても１１０°付近であった。
即ち、扇角度δを略１１０°に設けることにより、回転軸方向から見て、磁束付与磁石１１から磁束吸引磁石１２へ流れる磁束の向きを広い範囲にて平行にできる。
【００５４】
上述したように、磁束付与磁石１１と磁束吸引磁石１２を回転軸を中心とした略扇形形状に設け、その扇角度δを略１１０°に設けることにより、磁気検出チップ３の中心Ｏが回転中心Ｏ’から組付誤差等によってズレても、磁気検出チップ３を通過する磁束の角度が変化しなくなる。これによって、磁気検出チップ３の中心Ｏが回転中心Ｏ’から組付誤差等によってズレても、検出誤差の発生を防ぐことができる。
【００５５】
なお、扇角度δは、１１０°付近が最も好ましい。しかるに、角度差（θ−θ’）を０．５°以下に抑える場合は、扇角度δを１１０°±１０°以内とするものである。また、角度差（θ−θ’）を１°以下に抑える場合は、扇角度δを１１０°±２０°以内とすることで達成できる。
さらに、角度差（θ−θ’）を１．５°以下に抑える場合は、扇角度δを１１０°±３０°以内とするものでり、角度差（θ−θ’）を２°以下に抑える場合は、扇角度δを１１０°±４０°以内とすることで達成できる。
【００５６】
［第３実施例］
図８を用いて第３実施例を説明する。なお、図８は回転角度検出装置を回転軸方向から見た概略図である。
上記の第２実施例は、磁束付与磁石１１と磁束吸引磁石１２を回転軸を中心とした略扇形形状に設けることで、磁気検出チップ３が搭載される近傍の磁束の流れ方向を平行にした例を示した。
【００５７】
これに対し、この第３実施例は、磁束付与磁石１１と磁束吸引磁石１２を、それぞれ複数の直方体磁石１１ｂ、１２ｂによって構成し、その複数の直方体磁石１１ｂ、１２ｂを回転軸を中心として円弧状に配置したものであり、複数の直方体磁石１１ｂ、１２ｂによって第２実施例で示した扇形形状の磁石に近似させるものである。
このように設けることにより、扇形形状の磁石を用いた第２実施例と同様の効果を得ることができる。
なお、図８では、それぞれ２つの直方体磁石１１ｂ、１２ｂによって磁束付与磁石１１と磁束吸引磁石１２を構成した例を示したが、３つ以上の直方体磁石１１ｂ、１２ｂによって磁束付与磁石１１と磁束吸引磁石１２を構成して良いことはいうまでもない。
【００５８】
複数の直方体磁石１１ｂ、１２ｂによって近似的に形成される扇角度δは、第２実施例と同様の考え方で決定される。即ち、扇角度δは、１１０°付近が最も好ましく、角度差（θ−θ’）を０．５°以下に抑える場合は扇角度δを１１０°±１０°以内とし、角度差（θ−θ’）を１°以下に抑える場合は扇角度δを１１０°±２０°以内とし、角度差（θ−θ’）を１．５°以下に抑える場合は扇角度δを１１０°±３０°以内とし、角度差（θ−θ’）を２°以下に抑える場合は扇角度δを１１０°±４０°以内とするものである。
【００５９】
〔変形例〕
上記の実施例では、磁気検出素子の一例として磁気抵抗素子７（ＭＲＥ）を用いた例を示したが、ホール素子、ホールＩＣなど、他の磁気検出素子を用いても良い。
ここで、磁気抵抗素子７（ＭＲＥ）に代えて、ホール素子を用いた場合、ホール素子は、ホール素子の感度方向に与えられる磁束密度に比例した信号を発生するものであるため、組付誤差によってホール素子に与えられる磁束の向きがθからθ’に変化すると、検出誤差が発生する。具体的に、組付誤差によって変化する磁束の傾きをθ’、ホール素子に与えられる磁束密度の大きさをＢｇ、ホール素子の出力をＨｏｕｔとした場合、Ｈｏｕｔ＝Ｂｇ×ｃｏｓθ’となる。このため、ホール素子を用いる場合であっても、上記実施例で示したように、例え組付誤差が生じても、ホール素子の感度方向に与えられる磁束の向きが変化しないように、ホール素子の組付誤差の範囲で平行磁場を作る必要がある。
【００６０】
上記の実施例では、磁気検出チップ３に所定のオフセット角をなす２つの磁気検出素子（実施例では磁気抵抗素子７）を用い、２つの出力とａｒｃｔａｎ（アークタンジェント）で回転角度αを求めるとともに、磁束平行化手段も設けた例を示した。
しかるに、磁性体製のヨーク１０を用いる効果を得るのが目的の場合は、磁気検出素子を２つ用いる必要はなく、あるいは磁束平行化手段を設ける必要もなく、１つの磁気検出素子の出力で回転角度を求める回転角度検出装置に磁性体製のヨーク１０を用いて磁束発生手段５の効率化を図っても良い（請求項７に対応）。
【００６１】
上記の実施例では、磁気検出チップ３に所定のオフセット角をなす２つの磁気検出素子（実施例では磁気抵抗素子７）を用い、２つの出力とａｒｃｔａｎ（アークタンジェント）で回転角度αを求めるとともに、磁束平行化手段を設けた例を示した。
しかるに、磁性体製のヨーク１０を用いる効果を得るのが目的の場合は、磁束平行化手段を設ける必要はなく、２つの磁気検出素子の出力で回転角度を求める回転角度検出装置に磁性体製のヨーク１０を用いて磁束発生手段５の効率化を図っても良い（請求項８に対応）。
【００６２】
上記の実施例では、磁束平行化手段の一例として、磁束付与磁石１１および磁束吸引磁石１２を平行に設けて長くする例、扇形形状の磁石で磁束付与磁石１１および磁束吸引磁石１２を設ける例、複数の直方体の磁石を円弧状に配置する例を示した。
しかるに、着磁方向や着磁の密度を操作することによって磁束平行化手段を設けても良い。
【００６３】
上記の実施例では、磁束付与手段と磁束吸引手段をそれぞれ独立した永久磁石で構成した例を示したが、１つの磁石の一方または両方に磁性体を接合することで磁束付与手段や磁束吸引手段を設けても良い。
具体的な一例として、磁束付与手段または磁束吸引手段の一方を磁石で設け、磁束付与手段または磁束吸引手段の他方を鉄で設ける場合（磁石と鉄はヨーク１０等で磁気連結される）を説明する。
組付誤差の範囲で平行磁場を作る目的で、磁束付与手段と磁束吸引手段を、第２実施例で示したように、略扇形形状（円弧状）に設ける場合では、例えば鉄製の磁束付与手段または磁束吸引手段の他方の扇角度を１１０°に設ける場合、磁石よりなる磁束付与手段または磁束吸引手段の一方の扇角度δは、図９に示すように、１２５°付近が最も好ましい。なお、角度差（θ−θ’）を０．５°以下に抑える場合は、磁石の扇角度δを１２５°±２．５°以内とし、角度差（θ−θ’）を１°以下に抑える場合は、磁石の扇角度δを１１０°±５°以内とすることで達成できる。
【００６４】
上記の実施例では、磁気検出チップ３を固定し、磁束発生手段５を回転させた例を示したが、逆に磁束発生手段５を固定し、磁気検出チップ３を回転させる構造を採用しても良い。
上記の実施例では、回転角度検出装置の具体的な一例としてスロットルバルブ１の開度を検出する例を示したが、産業ロボットのアーム部の回転角度等、他の回転角度を検出するように設けても良い。
【図面の簡単な説明】
【図１】回転角度検出装置の回転軸方向に沿う概略断面図および回転軸方向から見た概略図である（第１実施例）。
【図２】スロットルバルブに組付けられた回転角度検出装置の断面図である（第１実施例）。
【図３】２つの磁気検出素子（磁気抵抗素子）のオフセット角を示す図および出力波形を示すグラフである（第１実施例）。
【図４】磁束平行化手段の説明図である（第１実施例）。
【図５】回転角度検出装置の回転軸方向に沿う概略断面図および回転軸方向から見た概略図である（第２実施例）。
【図６】磁束平行化手段の説明図である（第２実施例）。
【図７】内径寸法、外径寸法、扇角度を変化させた場合の角度差の変化を示すグラフである（第２実施例）。
【図８】回転角度検出装置を回転軸方向から見た概略図である（第３実施例）。
【図９】扇角度を変化させた場合の角度差の変化を示すグラフである（変形例）。
【図１０】回転角度検出装置の回転軸方向に沿う概略断面図および回転軸方向から見た概略図である（第１従来技術）。
【図１１】磁気検出素子（磁気抵抗素子）の出力波形を示すグラフである（第１従来技術）。
【図１２】２つの磁気検出素子（磁気抵抗素子）のオフセット角を示す図および出力波形を示すグラフである（第２従来技術）。
【図１３】回転角度検出装置の回転軸方向に沿う概略断面図および回転軸方向から見た概略図である（第２従来技術）。
【符号の説明】
３磁気検出チップ
５磁束発生手段
７磁気抵抗素子（磁気検出素子）
１０ヨーク
１１磁束付与磁石（磁束付与手段）
１１ａ磁束の発生部
１２磁束吸引磁石（磁束吸引手段）
１２ａ磁束の吸引部
Ａ磁気検出チップの組付誤差範囲
Ｄ磁束付与磁石および磁気吸引磁石の平行方向の長さ
Ｌ磁束発生手段と磁気検出チップの回転軸方向の距離[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation angle detection device that detects a relative rotation angle of two members (for example, a rotating member and a non-rotating member) in a non-contact manner.
[0002]
[Prior art]
(First prior art)
A schematic structure of a conventional rotation angle detection device that detects the relative rotation angle of two members without contact will be described with reference to FIGS.
In the rotation angle detection device, a magnetic detection element J1 (for example, a magneto-resistive element: MRE) disposed on a rotation axis and a magnetic flux generation unit J2 are directed to a side on which the magnetic detection element J1 in the rotation axis direction is disposed. A magnetic flux applying magnet J3 (an example of magnetic flux applying means) that applies a magnetic flux to the magnetic detecting element J1 and a magnetic flux attracting portion J4 is directed to the side where the magnetic detecting element J1 in the rotation axis direction is disposed. And a magnetic flux attracting magnet J5 (an example of magnetic flux attracting means) for attracting the released magnetic flux. The magnetic flux generating means J6 is composed of the magnetic flux providing magnet J3 and the magnetic flux attracting magnet J5 (for example, see Patent Document 1).
[0003]
Here, the magnetic flux providing magnet J3 and the magnetic flux attracting magnet J5 are arranged at a distance L in the rotation axis direction with respect to the magnetic detection element J1 (see FIG. 10A). It is disposed facing the detection element J1 at a distance from the periphery of the detection element J1 (see FIG. 10B).
When the relative rotation angle between the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5) and the magnetic detection element J1 changes, the magnetic flux density in the direction orthogonal to the magnetic detection surface of the magnetic detection element J1 changes. As a result, the output of the magnetic sensing element J1 changes (see FIG. 11).
[0004]
Here, the output of the magnetic detection element J1 composed of the MRE draws a sine curve as shown in FIG. In recent years, in order to increase the detection accuracy, various measures have been taken to make the slope of the sine curve of the detection range as linear as possible, and to expand the linearized detection range.
However, it is difficult to actually widen the linearized detection range, and in reality, the detection range in which the sine curve is linearized is limited to 60 ° (± 30 ° with reference to the output 0 of the sine curve). .
[0005]
(Second conventional technology)
Therefore, a technology has been proposed in which two magnetic detection elements J1 made of MRE are provided to improve the detection accuracy and expand the detection range.
According to this technique, as shown in FIG. 12A, two magnetic detection elements J1 are arranged so that the magnetic detection surface is separated by a predetermined angle (for example, an offset angle is 45 ° and an electric phase angle is 90 °). Is what you do. The two magnetic detection elements J1 are mounted as a magnetic detection chip J7 as shown in FIG.
When the relative rotation angle between the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5) and the magnetic detection chip J7 (the two magnetic detection elements J2) changes, the output of the two magnetic detection elements J1 becomes It changes as shown in FIG.
[0006]
Since the two output signals have an electrical phase difference of 90 ° as shown in FIG. 12B, the outputs of the two magnetic sensing elements J1 are proportional to sin2α and cos2α, respectively (α = rotation angle).
These two signals are mathematically represented by the following equations.
One signal X (α, T) = X0 (T) sin2α
The other signal Y (α, T) = Y0 (T) cos2α
[0007]
Assuming that the amplitudes (X0, Y0) of the two signals are the same (X0 = Y0), the unknown angle α is determined by the following equation.
α = (1/2) arctan (X / Y)
By providing two magnetic sensing elements J1 in this manner, it is possible to improve the detection accuracy and expand the detection range without linearizing the output of the magnetic sensing element J1 as in the first related art described above. (For example, see Non-Patent Document 1).
[0008]
[Patent Document 1]
JP 2001-304805 A
[Non-patent document 1]
Klaus Dietmayer, 1 other, "Non-contact angle measurement using KMZ41 and UZZ9001", Application Note AN00004, Philips Japan, January 17, 2000
[0009]
[Problems to be solved by the invention]
When the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5) and the magnetic detection chip J7 (the two magnetic detection elements J1) rotate relative to each other, the magnetic flux to the magnetic detection chip J7 is the same as the rotation angle. Needs to change direction.
This means that a deviation occurs between the center of rotation of the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5) and the center of the magnetic detection chip J7 (two magnetic detection elements J1) due to an assembly error or the like. Even in such a case, it should be considered so as to be satisfied.
[0010]
Therefore, in Non-Patent Document 1, as shown in FIG. 13, a raised part J9 is fixed on a substrate J8 on which a magnetic detection chip J7 is to be mounted, and the magnetic detection chip J7 is fixed on the raised part J9. Thus, a technique is disclosed in which the magnetic detection chip J7 is disposed inside the magnetic flux providing magnet J3 and the magnetic flux attraction magnet J5, and the direction of the magnetic flux in the space near the magnetic detection chip J7 is mounted is made uniform.
[0011]
However, as shown in FIG. 13, the technique of disposing the magnetic detection chip J7 inside the magnetic flux applying magnet J3 and the magnetic flux attraction magnet J5 is based on the fact that the magnetic detection chip J7 is originally directly soldered onto the substrate J8. The advantage of installation can be abandoned, and requires the above-mentioned raised part J9. This not only causes an increase in the number of components, but also requires wiring between the substrate J8 and the magnetic detection chip J7, which leads to complicated wiring.
[0012]
Further, since it is necessary to dispose the magnetic detection chip J7 inside the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5, the magnetic detecting chip J7 is separated from the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5) by a distance in the rotation axis direction. The magnetic detection chip J7 cannot be arranged. For this reason, the intended use is limited. That is, a rotation angle detection device in which the magnetic flux generation means J6 and the magnetic detection chip J7 are separated in the axial direction (for example, a rotation angle detection of a throttle valve in which a partition or the like is disposed between the magnetic flux generation means J6 and the magnetic detection chip J7 in the axial direction). Device).
[0013]
On the other hand, as shown in FIG. 10 (a), the magnetic flux generating magnet J3 has the magnetic flux generating portion J2 directed to the side where the magnetic detecting element J1 in the rotation axis direction is disposed, and the magnetic flux attraction magnet J5 has the rotation axis direction. Due to the configuration in which the magnetic flux attracting portion J4 is directed to the side where the magnetic detection element J1 is disposed, the magnetic flux disposed at a distance L in the rotation axis direction from the magnetic flux generating means J6 (the magnetic flux applying magnet J3 and the magnetic flux attracting magnet J5). A configuration is employed in which a magnetic flux a1 'is applied to a magnetic detection surface (a magnetic detection surface oriented in a direction perpendicular to the rotation axis) of the detection element J1.
However, the magnetic flux a2 'generated on the side different from the magnetic detection element J1 (lower side in FIG. 10A) is wasted without any use.
[0014]
[Object of the invention]
The present invention has been made in view of the above circumstances, and has the following three objects.
A first object is that a magnetic flux generating means (magnetic flux applying means and magnetic flux attracting means) and a magnetic detection chip (two magnetic detecting elements) can be arranged at a distance from each other in the direction of the rotation axis. Even if the magnetic detection chip and the magnetic detection chip are displaced in the direction orthogonal to the rotation axis due to an error in assembly, when the magnetic flux generating means and the magnetic detection chip are relatively rotated, the rotation angle is the same as the rotation angle. Another object of the present invention is to provide a rotation angle detection device that does not generate a detection error in which a direction of a magnetic flux changes with respect to a magnetic detection chip.
[0015]
A second object is that the magnetic flux generating means (magnetic flux applying magnet and magnetic flux attracting magnet) and the magnetic detection element can be arranged at a distance in the direction of the rotation axis, and the magnetic flux generating magnet and the magnetic flux attracting magnet can perform magnetic detection. To provide a rotation angle detection device that can suppress the waste of magnetic flux generated on the side different from the element and increase the magnetic flux given to the magnetic detection element, or reduce the size and weight of the magnetic flux applying magnet and the magnetic flux attracting magnet. is there.
[0016]
A third object is that a magnetic flux generating means (a magnetic flux applying magnet and a magnetic flux attracting magnet) and a magnetic detection chip (two magnetic detecting elements) can be arranged at a distance in the direction of the rotation axis, and the magnetic flux applying magnet can be provided. It is possible to suppress the waste of magnetic flux generated on the side different from the magnetic detection chip in the magnetic flux attracting magnet and increase the magnetic flux given to the magnetic detection chip, or to reduce the size and weight of the magnetic flux applying magnet and the magnetic flux attracting magnet. The present invention provides a rotation angle detection device.
[0017]
[Means for Solving the Problems]
[Means of claim 1]
The magnetic flux generating means according to claim 1 is a magnetic flux applying means in which a magnetic flux generating portion is directed to a side on which the magnetic detection chip in the rotation axis direction is disposed, and a magnetic flux generating means in which the magnetic detection chip in the rotation axis direction is disposed. A magnetic flux attracting unit to which a magnetic flux attracting unit is directed.
By employing this configuration, even if the magnetic flux generating means (magnetic flux applying means and magnetic flux attracting means) and the magnetic detection chip are arranged at a distance in the direction of the rotation axis, magnetic flux can be applied to the two magnetic detection elements. it can.
With this arrangement, when the relative rotation angle between the magnetic flux generation unit and the magnetic detection chip changes in a state where the magnetic flux generation unit and the magnetic detection chip are arranged at a distance in the rotation axis direction, the relative rotation angle of the two magnetic detection elements is changed. An output corresponding to the change is generated. That is, a change in the relative rotation angle can be detected in a state where the magnetic flux generating means and the magnetic detection chip are arranged at a distance in the direction of the rotation axis.
[0018]
Further, there is provided a magnetic flux collimating means for making the flow direction of the magnetic flux from the magnetic flux applying means to the magnetic flux attraction means via the magnetic detection chip parallel within a range of an assembly error of the magnetic detection chip.
Thus, even when the magnetic flux generating means and the magnetic detection chip are displaced in the direction orthogonal to the rotation axis due to an error in assembly, if the magnetic flux generating means and the magnetic detection chip rotate relatively, the rotation Like the angle, the direction of the magnetic flux relative to the magnetic sensing chip changes. Therefore, it is possible to prevent a detection error from occurring even if an error occurs in assembly.
[0019]
That is, the rotation angle detecting device according to the first aspect detects the change in the relative rotation angle between the magnetic flux generation means and the magnetic detection chip in a state where the magnetic flux generation means and the magnetic detection chip are arranged at a distance in the rotation axis direction. The detection can be performed by the output of the magnetic detection element, and the generation of the detection error can be prevented even if an error occurs in the assembly between the magnetic flux generating means and the magnetic detection chip.
[0020]
[Means of Claim 2]
In the rotation angle detecting device employing the means of claim 2, the magnetic flux applying means and the magnetic flux attracting means are arranged in parallel with a rotation axis therebetween, and the length of each of the magnetic flux applying means and the magnetic flux attracting means along the parallel direction is adjusted. The magnetic flux collimating means is provided by increasing the length.
With this arrangement, the direction of the magnetic flux from the magnetic flux applying means to the magnetic flux attracting means can be parallelized within the range of the assembly error of the magnetic detection chip.
[0021]
[Means of Claim 3]
The rotation angle detecting device adopting the means of claim 3 is provided with a magnetic flux collimating means by making the magnetic flux applying means and the magnetic flux attracting means substantially fan-shaped around the rotation axis.
With this arrangement, the direction of the magnetic flux from the magnetic flux applying means to the magnetic flux attracting means can be parallelized within the range of the assembly error of the magnetic detection chip.
[0022]
[Means of Claim 4]
In the rotation angle detecting device employing the means of claim 4, the magnetic flux applying means and the magnetic flux attracting means are each constituted by a plurality of rectangular parallelepipeds, and the plurality of rectangular parallelepipeds are arranged in an arc around the rotation axis to make the magnetic flux parallel. Means are provided.
With this arrangement, the direction of the magnetic flux from the magnetic flux applying means to the magnetic flux attracting means can be parallelized within the range of the assembly error of the magnetic detection chip.
[0023]
[Means of claim 5]
The magnetic flux applying means and the magnetic flux attracting means of the rotation angle detecting device adopting the means of claim 5 are permanent magnets magnetized in the direction of the rotation axis, and the magnetic flux applying means and the magnetic flux attracting means have opposite magnetization directions.
With this arrangement, the magnetic flux is applied to the two magnetic detection elements of the magnetic detection chip from the magnetic flux applying means and the magnetic flux attracting means, each of which is made of a permanent magnet and arranged at a distance from the magnetic detection chip in the rotation axis direction. be able to.
[0024]
[Means of claim 6]
The rotation angle detecting device adopting the means of claim 6 is characterized in that a yoke made of a magnetic material is arranged on a side of the magnetic flux applying means composed of a permanent magnet and the magnetic flux attracting means on a side different from the magnetic detection chip, and the magnetic flux applying means and the magnetic flux The suction means is magnetically coupled with a yoke on a side different from the magnetic detection chip.
With such provision, it is possible to suppress the waste of the magnetic flux generated on the side different from the magnetic detection element in the magnetic flux applying means and the magnetic flux attraction means made of a permanent magnet, and as a result, the magnetic flux applied to the magnetic detection element is increased. be able to. Alternatively, it is possible to reduce the size and weight of the magnetic flux applying means and the magnetic flux attracting means made of permanent magnets.
[0025]
[Means of claim 7]
A rotation angle detecting device employing the means of claim 7 is provided with a magnetic flux providing magnet having a magnetic flux generation unit directed to the side where the magnetic detection element in the rotation axis direction is disposed, and a magnetic detection element in the rotation axis direction. And a magnetic flux attracting magnet having a magnetic flux attracting portion directed to the opposite side.
By employing this configuration, even when the magnetic flux generating means (the magnetic flux applying magnet and the magnetic flux attracting magnet) and the magnetic detection element are arranged at a distance from each other in the rotation axis direction, a magnetic flux can be applied to the magnetic detection element.
With this configuration, when the relative rotation angle between the magnetic flux generating means and the magnetic detection element changes in a state where the magnetic flux generation means and the magnetic detection element are arranged at a distance in the rotation axis direction, the magnetic detection element responds to the change in the relative rotation angle. Output occurs. That is, a change in the relative rotation angle can be detected in a state where the magnetic flux generating means and the magnetic detection element are arranged at a distance in the direction of the rotation axis.
[0026]
Further, in the rotation angle detecting device adopting the means of claim 7, a yoke made of a magnetic material is arranged on a side of the magnetic flux applying magnet and the magnetic flux attracting magnet different from the magnetic detecting element, and the magnetic flux applying magnet and the magnetic flux attracting magnet are arranged. The magnetic detection element is different from the magnetic detection element described above in that the yoke is magnetically coupled with a yoke.
With this arrangement, it is possible to suppress the waste of the magnetic flux generated in the magnetic flux applying magnet and the magnetic flux attracting magnet on a side different from the magnetic detection element, and as a result, it is possible to increase the magnetic flux applied to the magnetic detection element. Alternatively, the size and weight of the magnetic flux providing magnet and the magnetic flux attracting magnet can be reduced.
[0027]
[Means of claim 8]
A rotation angle detecting device employing the means of claim 8 is provided with a magnetic flux providing magnet having a magnetic flux generation part directed to the side where the magnetic detection chip in the rotation axis direction is disposed, and a magnetic detection chip in the rotation axis direction. And a magnetic flux attracting magnet having a magnetic flux attracting portion directed to the opposite side.
By adopting this configuration, even if the magnetic flux generating means (magnetic flux applying magnet and magnetic flux attracting magnet) and the magnetic detection chip (two magnetic detection elements) are arranged at a distance in the direction of the rotation axis, the magnetic detection chip A magnetic flux can be applied to the two magnetic sensing elements.
With this arrangement, when the relative rotation angle between the magnetic flux generation unit and the magnetic detection chip changes in a state where the magnetic flux generation unit and the magnetic detection chip are arranged at a distance in the rotation axis direction, the relative rotation angle of the two magnetic detection elements is changed. An output corresponding to the change is generated. That is, a change in the relative rotation angle can be detected in a state where the magnetic flux generating means and the magnetic detection chip are arranged at a distance in the direction of the rotation axis.
[0028]
Further, in the rotation angle detecting device adopting the means of claim 8, a yoke made of a magnetic material is arranged on a side of the magnetic flux applying magnet and the magnetic flux attracting magnet different from the magnetic detection chip, and the magnetic flux applying magnet and the magnetic flux attracting magnet are arranged. A magnetic detection chip is magnetically coupled to a different side by a yoke.
With such provision, it is possible to suppress the waste of the magnetic flux generated on the side different from the magnetic detection chip in the magnetic flux applying magnet and the magnetic flux attracting magnet, and as a result, it is possible to increase the magnetic flux applied to the two magnetic detection elements. it can. Alternatively, the size and weight of the magnetic flux providing magnet and the magnetic flux attracting magnet can be reduced.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described using three examples and modifications.
[First embodiment]
A first embodiment will be described with reference to FIGS. FIG. 1A is a schematic cross-sectional view of a rotation angle detection device along the rotation axis direction, and FIG. 1B is a schematic diagram of the rotation angle detection device as viewed from the rotation axis direction. FIG. 2 is a cross-sectional view of a rotation angle detection device attached to a throttle valve.
[0030]
First, the basic configuration of the rotation angle detection device will be described with reference to FIG.
The rotation angle detection device shown in this embodiment is for detecting the rotation angle (opening) of the throttle valve 1, and includes a magnetic detection chip 3 mounted on a circuit board 2 (fixed member) and a rotor 4 ( And a magnetic flux generating means 5 fixed to the rotating member).
[0031]
Since the space in which the magnetic flux generating means 5 is disposed is connected to the intake side of the engine or the atmosphere, there are substances such as exhaust gas and moisture which may adversely affect the electronic components mounted on the circuit board 2.
Therefore, the magnetic detection chip 3 and the magnetic flux generating means 5 are arranged at a distance L in the direction of the rotation axis of the rotor 4 as shown in FIG. The shielding member 6 is arranged between the magnetic flux generating means 5 in the rotation axis direction to separate the space where the magnetic detection chip 3 is arranged from the space where the magnetic flux generating means 5 is arranged. As a result, substances that may adversely affect the electronic components, such as exhaust gas and moisture, do not enter the space where the circuit board 2 is disposed.
[0032]
As shown in FIG. 3A, the magnetic detection chip 3 includes two magnetoresistive elements 7 (an example of a magnetic detection element) whose magnetic detection surfaces are arranged at an angle of 45 ° (an example of a predetermined angle). An electric component to be mounted. The magnetic detection surfaces of the two magnetoresistive elements 7 are oriented in a direction perpendicular to the rotation axis of the rotor 4 and the magnetic detection surfaces of the two magnetoresistive elements 7 (the center O of the magnetic detection chip 3) are It is arranged so as to coincide with the rotation center O ′ of the rotor 4.
[0033]
The rotor 4 includes a yoke 10 fixed to a shaft 8 of the throttle valve 1 by a fastening means 9 such as a screw, and a magnetic flux generating means 5 fixed to the yoke 10.
As shown in FIG. 1B, the magnetic flux generating means 5 is a magnetic flux applying magnet 11 (an example of a magnetic flux applying means) which is disposed opposite to each side of the magnetic detection chip 3 with a distance when viewed from the rotation axis direction. And a magnetic flux attracting magnet 12 (an example of magnetic flux attracting means).
[0034]
As shown in FIG. 1A, the magnetic flux providing magnet 11 has a magnetic flux generating portion 11a directed to the side where the magnetic detection chip 3 is arranged in the rotation axis direction. Are magnetized such that the N pole faces the side on which is disposed.
In the magnetic flux attracting magnet 12, the magnetic flux attracting portion 12a is directed to the side where the magnetic detection chip 3 is disposed in the rotation axis direction, and specifically, the S pole is directed to the side where the magnetic detection chip 3 is disposed. It is a magnet magnetized as follows.
[0035]
By using such a magnetic flux providing magnet 11 and a magnetic flux attracting magnet 12, even if the magnetic flux generating means 5 and the magnetic detection chip 3 are arranged at a distance L in the rotation axis direction, as shown in FIG. Then, the magnetic flux a1 can be applied to the magnetic detection chip 3 (the magnetic detection surfaces of the two magnetoresistive elements 7).
Thus, even when the magnetic flux generation means 5 and the magnetic detection chip 3 are arranged at a distance L in the direction of the rotation axis, if the relative rotation angle between the magnetic flux generation means 5 and the magnetic detection chip 3 changes, 2 An output corresponding to a change in the relative rotation angle is generated from the two magnetic resistance elements 7. That is, a change in the relative rotation angle can be detected in a state where the magnetic flux generating means 5 and the magnetic detection chip 3 are arranged at a distance L in the direction of the rotation axis (first effect).
[0036]
Specifically, as described in the section of the related art, the two magneto-resistive elements 7 have an offset angle of 45 ° and an electric phase angle of 90 °, so that the magnetic flux is generated as the rotor 4 rotates. When the generating means 5 (the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12) rotate, the outputs of the two magnetoresistive elements 7 change as shown in FIG.
[0037]
Since the two output signals have an electrical phase difference of 90 ° as shown in FIG. 3B, the outputs of the two magnetoresistive elements 7 are proportional to sin2α and cos2α, respectively (α = rotation angle).
These two signals are mathematically represented by the following equations.
One signal X (α, T) = X0 (T) sin2α
The other signal Y (α, T) = Y0 (T) cos2α
[0038]
Assuming that the amplitudes (X0, Y0) of the two signals are the same (X0 = Y0), the unknown angle α is determined by the following equation.
α = (1/2) arctan (X / Y)
Thus, by providing two magnetoresistive elements 7, it is possible to improve the detection accuracy and expand the detection range.
[0039]
On the other hand, the yoke 10 is provided by a magnetic material such as iron, and is disposed on a side different from the side on which the magnetic detection chip 3 is disposed to perform magnetic coupling between the magnetic flux providing magnet 11 and the magnetic flux attracting magnet 12. Things.
With this arrangement, as shown in FIG. 1A, the magnetic flux a2 generated on the side different from the side on which the magnetic detection chip 3 is arranged flows efficiently through the yoke 10. As a result, waste of the magnetic flux in the magnetic flux generating means 5 is suppressed, and as a result, the magnetic flux given to the magnetic detection chip 3 can be increased. Alternatively, it is possible to reduce the size and weight of the magnetic flux providing magnet 11 and the magnetic flux attracting magnet 12 (second effect).
[0040]
Here, the magnetic flux generating means 5 has a magnetic flux paralleling direction in which the flow direction of the magnetic flux from the magnetic flux providing magnet 11 to the magnetic flux attracting magnet 12 via the magnetic detection chip 3 is parallel within an assembling error range of the magnetic detection chip 3. Means is provided.
As shown in FIG. 4 (a), the magnetic flux collimating means of this embodiment is provided with a magnetic flux applying magnet 11 and a magnetic flux attracting magnet 12 as rectangular parallelepiped magnets, and is arranged in parallel with a rotation axis therebetween. The lengths D of the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 along the length are provided long.
[0041]
This will be described with reference to FIGS.
As shown in FIG. 4A, the center O of the magnetic detection chip 3 is assembled so as to coincide with the center of rotation O ′.
However, in reality, the center O of the magnetic detection chip 3 may deviate from the rotation center O 'due to an assembly error or the like.
[0042]
As shown in FIG. 4A, when the center O of the magnetic detection chip 3 was assembled so as to coincide with the rotation center O ′, the angle of the magnetic flux passing through the magnetic detection chip 3 was θ. In this case, as shown in FIG. 4B, when the center O of the magnetic detection chip 3 deviates from the rotation center O ′ by more than the range of the assembly error, the angle of the magnetic flux passing through the magnetic detection chip 3 becomes θ ′. (Θ ≠ θ ').
[0043]
However, since the length D of each of the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 is set to be long, the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 are provided within a range indicated by a circle A (a circle centered on the rotation center O ′) in FIG. In the assembly error range of the magnetic detection chip 3, the flow direction of the magnetic flux from the magnetic flux providing magnet 11 to the magnetic flux attraction magnet 12 via the magnetic detection chip 3 becomes parallel.
Therefore, even if the center O of the magnetic detection chip 3 deviates from the rotation center O 'within a predetermined assembly error, the angle of the magnetic flux passing through the magnetic detection chip 3 does not change. That is, even when the center O of the magnetic detection chip 3 and the rotation center O ′ are shifted within the range of an error in assembly, when the magnetic flux generating means 5 and the magnetic detection chip 3 are relatively rotated, the shift occurs. The direction of the magnetic flux with respect to the magnetic detection chip 3 is changed in the same manner as in the case where there is no magnetic field. For this reason, even if an error in assembly occurs, occurrence of a detection error is prevented (third effect).
[0044]
[Effect of First Embodiment]
The rotation angle detection device according to the present embodiment has the following four effects.
(1) The magnetic flux imparting magnet 11 is provided so that the magnetic flux generating portion 11a faces the side where the magnetic detection chip 3 in the rotation axis direction is disposed, and the magnetic flux is provided on the side where the magnetic detection chip 3 in the rotation axis direction is disposed. By providing the magnetic flux attracting magnet 12 so that the attracting portion 12a faces, even if the magnetic flux generating means 5 and the magnetic detection chip 3 are arranged at a distance L in the direction of the rotation axis, the magnetic detection chip 3 (two magnetic resistances) can be used. A magnetic flux can be applied to the magnetic detection surface of the element 7, and a change in the relative rotation angle can be detected by the outputs of the two magnetoresistive elements 7.
[0045]
(2) The magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are magnetically coupled by a magnetic yoke 10 on a side different from the side on which the magnetic detection chip 3 is disposed, so that the side on which the magnetic detection chip 3 is disposed. It is possible to suppress the waste of the magnetic flux generated on the side different from the above. As a result, the magnetic flux applied to the magnetic detection chip 3 can be increased. Alternatively, the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 can be reduced in size and weight.
[0046]
(3) The magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 are provided as rectangular parallelepiped magnets, and are arranged in parallel with the rotation axis therebetween, and the lengths D of the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 oriented in the parallel direction are increased. With this arrangement, the angle of the magnetic flux passing through the magnetic detection chip 3 does not change even if the center O of the magnetic detection chip 3 deviates from the rotation center O 'within a predetermined assembly error range. As a result, even if the center O of the magnetic detection chip 3 deviates from the rotation center O 'within a range of a predetermined assembly error, it is possible to prevent a detection error from occurring.
[0047]
(4) With the magnetic flux generating means 5 and the magnetic detection chip 3 disposed at a distance L in the direction of the rotation axis, even if the mounting position of the magnetic detection chip 3 is shifted within a predetermined mounting error range, Generation of a detection error can be prevented. As a result, the raised parts (see J9 in FIG. 13) as described in the section of the related art can be eliminated, and the magnetic detection chip 3 can be directly mounted on the circuit board 2. Therefore, the magnetic detection chip 3 can be directly mounted on the circuit board 2 by soldering or the like, and the productivity is improved. Further, since the raising member is not used, the complexity of the wiring due to the use of the raising component can be solved.
[0048]
[Second embodiment]
A second embodiment will be described with reference to FIGS. The same reference numerals as those in the first embodiment after the second embodiment denote the same functions unless otherwise specified.
In the first embodiment, the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are provided as rectangular parallelepiped magnets, arranged in parallel with a rotation axis therebetween, and each of the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 oriented in the parallel direction. The example in which the length of the magnetic flux D within the error range of assembling the magnetic detection chip 3 is made parallel by providing a longer length D is shown.
[0049]
On the other hand, in the second embodiment, as shown in FIG. 5B, the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 are provided in a substantially sector shape around the rotation axis, so that the magnetic detection chip 3 The flow direction of the magnetic flux within the assembly error range is made parallel.
This will be described specifically.
The shapes of the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are determined by the thickness α in the rotation axis direction, the inner diameter dimension β, the outer diameter dimension γ, and the fan angle δ, and the thickness α, the inner diameter dimension β, and the outer diameter dimension γ affects the strength of the magnetic flux applied to the magnetic detection chip 3, but does not contribute much to the flow direction of the magnetic flux from the magnetic flux providing magnet 11 to the magnetic flux attracting magnet 12.
[0050]
FIGS. 6A and 6B show the flow of magnetic flux when the fan angle δ is not appropriate. 6A shows a case where the fan angle δ is smaller than the appropriate range, and FIG. 6B shows a case where the fan angle δ is larger than the appropriate range.
If the fan angle δ is smaller than the appropriate range, the direction of the magnetic flux expands outward as the distance from the rotation center O ′ increases. For this reason, when the angle of the magnetic flux at the rotation center O ′ is θ, as shown in FIG. 6A, when the center O of the magnetic detection chip 3 deviates greatly from the rotation center O ′, the magnetic detection chip 3 passes through the magnetic detection chip 3. The angle of the magnetic flux becomes θ ′, and an angle difference occurs between θ and θ ′ (θ ≠ θ ′).
[0051]
On the contrary, when the fan angle δ is larger than the appropriate range, the direction of the magnetic flux is depressed inward as the distance from the rotation center O ′ increases. For this reason, when the angle of the magnetic flux at the rotation center O ′ is θ, as shown in FIG. 6B, when the center O of the magnetic detection chip 3 is largely displaced from the rotation center O ′, the magnetic detection chip 3 passes through the magnetic detection chip 3. The angle of the magnetic flux becomes θ ′, and an angle difference occurs between θ and θ ′ (θ ≠ θ ′).
[0052]
The inventors of the present application believe that since the direction of the magnetic flux expands outward and concaves inward, the magnet shape including the optimal fan angle exists, and simulations and trials of various shapes were performed. I sought characteristics in my work.
The distance L between the magnetic flux generating means 5 and the magnetic detection chip 3 in the rotation axis direction is 3 mm, and the center deviation of the center O of the magnetic detection chip 3 with respect to the rotation center O ′ of the magnetic flux generation means 5 is in the X direction (in the direction orthogonal to the rotation axis). Assuming 1.2 mm in the arbitrary line direction and 1.2 mm in the Y direction (the direction orthogonal to the rotation axis and the direction orthogonal to the X direction), each of the inner diameter dimension β, the outer diameter dimension γ, and the fan angle δ is 1 The change in the angle difference (θ−θ ′) between the above-described magnetic flux angles θ and θ ′ was obtained by changing one of the values. FIGS. 7A to 7C show changes in the angle difference (θ−θ ′). Here, the angle difference (θ−θ ′) appears as an error of the rotation angle detection device.
FIG. 7A is a graph showing a change amount of the angle difference (θ−θ ′) when the inner diameter dimension β is changed, and FIG. 7B is a graph showing the angle difference when the outer diameter dimension γ is changed. FIG. 7C is a graph showing the amount of change in (θ−θ ′), and FIG. 7C is a graph showing the amount of change in the angle difference (θ−θ ′) when the fan angle δ is changed.
[0053]
As can be seen from FIGS. 7A and 7B, even if the inner diameter dimension β and the outer diameter dimension γ are changed, the angle difference (θ−θ ′) does not change much.
As can be read from FIG. 7C, the angle difference (θ−θ ′) becomes the smallest when the fan angle δ is around 110 °, and the fan angle δ increases from 110 °, or the fan angle δ increases from 110 °. As the angle δ decreases, the angle difference (θ−θ ′) increases.
The fan angle δ at which the angle difference (θ−θ ′) became the smallest was around 110 ° even when the distance L was changed within a range of 3 mm ± 0.5 mm.
That is, by providing the fan angle δ at approximately 110 °, the direction of the magnetic flux flowing from the magnetic flux providing magnet 11 to the magnetic flux attracting magnet 12 can be made parallel in a wide range when viewed from the rotation axis direction.
[0054]
As described above, the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 are provided in a substantially sector shape with the rotation axis as the center, and the fan angle δ is provided at approximately 110 °, so that the center O of the magnetic detection chip 3 becomes the rotation center. Even if the magnetic flux deviates from O ′ due to an assembly error or the like, the angle of the magnetic flux passing through the magnetic detection chip 3 does not change. Thus, even if the center O of the magnetic detection chip 3 deviates from the rotation center O ′ due to an assembly error or the like, it is possible to prevent a detection error from occurring.
[0055]
The fan angle δ is most preferably around 110 °. However, when the angle difference (θ−θ ′) is suppressed to 0.5 ° or less, the fan angle δ is set to 110 ° ± 10 ° or less. In addition, when the angle difference (θ−θ ′) is suppressed to 1 ° or less, it can be achieved by setting the fan angle δ to 110 ° ± 20 °.
Further, when the angle difference (θ−θ ′) is suppressed to 1.5 ° or less, the fan angle δ is set to 110 ° ± 30 ° or less, and the angle difference (θ−θ ′) is set to 2 ° or less. This can be achieved by setting the fan angle δ within 110 ° ± 40 °.
[0056]
[Third embodiment]
A third embodiment will be described with reference to FIG. FIG. 8 is a schematic view of the rotation angle detection device viewed from the rotation axis direction.
In the second embodiment, the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are provided in a substantially sector shape with the rotation axis as the center, so that the flow directions of the magnetic flux near the mounting of the magnetic detection chip 3 are made parallel. Examples have been given.
[0057]
On the other hand, in the third embodiment, the magnetic flux imparting magnet 11 and the magnetic flux attracting magnet 12 are respectively constituted by a plurality of rectangular parallelepiped magnets 11b and 12b, and the plurality of rectangular parallelepiped magnets 11b and 12b are formed in an arc shape around the rotation axis. And a plurality of rectangular parallelepiped magnets 11b and 12b approximate the fan-shaped magnet shown in the second embodiment.
With this arrangement, the same effect as that of the second embodiment using the sector-shaped magnet can be obtained.
FIG. 8 shows an example in which the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are respectively constituted by two rectangular parallelepiped magnets 11b and 12b. However, the magnetic flux applying magnet 11 and the magnetic flux attracting magnet are constituted by three or more rectangular magnets 11b and 12b. It goes without saying that the magnet 12 may be configured.
[0058]
The fan angle δ approximately formed by the plurality of rectangular magnets 11b and 12b is determined based on the same concept as in the second embodiment. That is, the fan angle δ is most preferably around 110 °, and when the angle difference (θ−θ ′) is suppressed to 0.5 ° or less, the fan angle δ is set within 110 ° ± 10 °, and the angle difference (θ−θ) is set. When ') is suppressed to 1 ° or less, the fan angle δ is within 110 ° ± 20 °, and when the angle difference (θ−θ') is suppressed to 1.5 ° or less, the fan angle δ is within 110 ° ± 30 °. When the angle difference (θ−θ ′) is suppressed to 2 ° or less, the fan angle δ is set within 110 ° ± 40 °.
[0059]
(Modification)
In the above-described embodiment, an example in which the magnetoresistive element 7 (MRE) is used as an example of the magnetic detection element has been described. However, another magnetic detection element such as a Hall element or a Hall IC may be used.
Here, when a Hall element is used instead of the magnetoresistive element 7 (MRE), the Hall element generates a signal proportional to the magnetic flux density given in the sensitivity direction of the Hall element. When the direction of the magnetic flux applied to the Hall element changes from θ to θ ′, a detection error occurs. Specifically, when the inclination of the magnetic flux that changes due to the assembly error is θ ′, the magnitude of the magnetic flux density given to the Hall element is Bg, and the output of the Hall element is Hout, Hout = Bg × cos θ ′. For this reason, even when the Hall element is used, as shown in the above embodiment, even if an assembly error occurs, the Hall element is controlled so that the direction of the magnetic flux applied in the sensitivity direction of the Hall element does not change. It is necessary to create a parallel magnetic field within the range of the assembly error.
[0060]
In the above embodiment, the magnetic detection chip 3 uses two magnetic detection elements (in the embodiment, the magnetic resistance element 7) forming a predetermined offset angle, and obtains the rotation angle α from two outputs and arctan (arc tangent). The example in which the magnetic flux collimating means is also provided is shown.
However, if the purpose is to obtain the effect of using the yoke 10 made of a magnetic material, it is not necessary to use two magnetic detecting elements or to provide a magnetic flux collimating means, and the output of one magnetic detecting element can be used. The magnetic flux generating means 5 may be made more efficient by using a yoke 10 made of a magnetic material in the rotation angle detecting device for obtaining the rotation angle (corresponding to claim 7).
[0061]
In the above embodiment, the magnetic detection chip 3 uses two magnetic detection elements (in the embodiment, the magnetic resistance element 7) forming a predetermined offset angle, and obtains the rotation angle α from two outputs and arctan (arc tangent). The example in which the magnetic flux collimating means is provided is shown.
However, if it is intended to obtain the effect of using the yoke 10 made of a magnetic material, it is not necessary to provide a magnetic flux collimating means, and the rotation angle detection device that obtains the rotation angle from the outputs of the two magnetic detection elements is made of a magnetic material. The efficiency of the magnetic flux generating means 5 may be improved by using the yoke 10 (corresponding to claim 8).
[0062]
In the above embodiment, as an example of the magnetic flux collimating means, an example in which the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are provided in parallel and lengthened, an example in which the magnetic flux applying magnet 11 and the magnetic flux attracting magnet 12 are provided by fan-shaped magnets, An example in which a plurality of rectangular parallelepiped magnets are arranged in an arc has been described.
However, the magnetic flux parallelizing means may be provided by manipulating the magnetization direction and the magnetization density.
[0063]
In the above embodiment, the example in which the magnetic flux applying means and the magnetic flux attracting means are constituted by independent permanent magnets has been described. However, the magnetic flux applying means and the magnetic flux attracting means are joined by joining a magnetic material to one or both of one magnet. May be provided.
As a specific example, a case where one of the magnetic flux applying means or the magnetic flux attracting means is provided by a magnet and the other of the magnetic flux applying means or the magnetic flux attracting means is provided by iron (the magnet and the iron are magnetically connected by the yoke 10 or the like) will be described. I do.
When the magnetic flux applying means and the magnetic flux attracting means are provided in a substantially sector shape (arc shape) as shown in the second embodiment for the purpose of producing a parallel magnetic field within the range of the assembly error, for example, a magnetic flux applying means made of iron Alternatively, when the other fan angle of the magnetic flux attraction means is provided at 110 °, the one fan angle δ of one of the magnetic flux applying means and the magnetic flux attraction means, which is composed of a magnet, is most preferably around 125 ° as shown in FIG. When the angle difference (θ−θ ′) is suppressed to 0.5 ° or less, the fan angle δ of the magnet is set to 125 ° ± 2.5 ° or less, and the angle difference (θ−θ ′) is set to 1 ° or less. This can be achieved by keeping the fan angle δ of the magnet within 110 ° ± 5 °.
[0064]
In the above embodiment, the example in which the magnetic detection chip 3 is fixed and the magnetic flux generating means 5 is rotated has been described. However, a structure in which the magnetic flux generating means 5 is fixed and the magnetic detection chip 3 is rotated is adopted. Is also good.
In the above-described embodiment, an example in which the opening degree of the throttle valve 1 is detected as a specific example of the rotation angle detection device has been described. However, other rotation angles such as the rotation angle of an arm of an industrial robot are detected. It may be provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view along a rotation axis direction of a rotation angle detection device and a schematic view as viewed from the rotation axis direction (first embodiment).
FIG. 2 is a cross-sectional view of a rotation angle detection device attached to a throttle valve (first embodiment).
FIG. 3 is a diagram showing an offset angle of two magnetic detecting elements (magnetic resistance elements) and a graph showing an output waveform (first embodiment).
FIG. 4 is an explanatory view of a magnetic flux collimating means (first embodiment).
FIG. 5 is a schematic sectional view of the rotation angle detection device along the rotation axis direction and a schematic view seen from the rotation axis direction (second embodiment).
FIG. 6 is an explanatory view of a magnetic flux collimating means (second embodiment).
FIG. 7 is a graph showing changes in the angle difference when the inner diameter, the outer diameter, and the fan angle are changed (second embodiment).
FIG. 8 is a schematic view of a rotation angle detection device viewed from a rotation axis direction (third embodiment).
FIG. 9 is a graph showing a change in the angle difference when the fan angle is changed (modification).
FIG. 10 is a schematic cross-sectional view along a rotation axis direction of the rotation angle detection device and a schematic view as viewed from the rotation axis direction (first related art).
FIG. 11 is a graph showing an output waveform of a magnetic detection element (magnetoresistive element) (first conventional technique).
FIG. 12 is a diagram showing an offset angle of two magnetic detection elements (magnetoresistive elements) and a graph showing an output waveform (second related art).
FIG. 13 is a schematic cross-sectional view taken along a rotation axis direction of the rotation angle detection device and a schematic diagram viewed from the rotation axis direction (second related art).
[Explanation of symbols]
3 Magnetic detection chip
5 Magnetic flux generating means
7 Magnetic resistance element (magnetic detection element)
10 York
11 Magnet for applying magnetic flux (magnetic flux applying means)
11a Magnetic flux generator
12. Magnetic flux attracting magnet (magnetic flux attracting means)
12a Magnetic flux suction part
A. Error range of assembly of magnetic detection chip
D Length of magnetic flux applying magnet and magnetic attraction magnet in parallel direction
L Distance between the magnetic flux generating means and the magnetic detection chip in the rotation axis direction

Claims

略回転軸上に配置され、回転軸の直交方向に磁気検出面が所定の角度を隔てて配置された２つの磁気検出素子を有する磁気検出チップと、
この磁気検出チップに対して回転軸方向に距離を隔てて配置されるとともに、回転軸方向から見て前記磁気検出チップの両側に距離を隔てて対向配置され、
回転軸方向の前記磁気検出チップが配置された側に磁束の発生部が向けられる磁束付与手段、および回転軸方向の前記磁気検出チップが配置された側に磁束の吸引部が向けられて前記磁束付与手段から放出された磁束を吸引する磁束吸引手段を備える磁束発生手段と、を具備し、
前記磁束発生手段は、前記磁束付与手段から前記磁気検出チップを介して前記磁束吸引手段に向かう磁束の流れ方向を、前記磁気検出チップの組付誤差範囲内において平行にする磁束平行化手段を備えるものであり、
前記磁気検出チップと前記磁束発生手段の相対回転角度の変化を、前記２つの磁気検出素子を通過する磁束によって検出する回転角度検出装置。A magnetic detection chip having two magnetic detection elements arranged substantially on the rotation axis and having a magnetic detection surface arranged at a predetermined angle in a direction orthogonal to the rotation axis;
Along with the magnetic detection chip is disposed at a distance in the direction of the rotation axis, and is disposed opposite to both sides of the magnetic detection chip at a distance when viewed from the direction of the rotation axis,
A magnetic flux applying means for directing a magnetic flux generation unit to a side on which the magnetic detection chip is disposed in a rotation axis direction, and a magnetic flux suction unit for directing a magnetic flux attraction unit to a side on which the magnetic detection chip is disposed in the rotation axis direction Magnetic flux generating means including a magnetic flux attracting means for attracting the magnetic flux emitted from the applying means,
The magnetic flux generating means includes a magnetic flux parallelizing means for making a flow direction of magnetic flux from the magnetic flux applying means to the magnetic flux attraction means via the magnetic detection chip toward the magnetic flux attraction means within an assembly error range of the magnetic detection chip. Things,
A rotation angle detection device for detecting a change in a relative rotation angle between the magnetic detection chip and the magnetic flux generating means by a magnetic flux passing through the two magnetic detection elements.

請求項１に記載の回転角度検出装置において、
前記磁束平行化手段は、前記磁束付与手段と前記磁束吸引手段を回転軸を隔てて平行配置して、この平行方向に沿う前記磁束付与手段と前記磁束吸引手段のそれぞれの長さを長くすることによって設けられたことを特徴とする回転角度検出装置。The rotation angle detection device according to claim 1,
The magnetic flux parallelizing means may be configured such that the magnetic flux applying means and the magnetic flux attracting means are arranged in parallel with a rotation axis therebetween, and the lengths of the magnetic flux applying means and the magnetic flux attracting means along the parallel direction are lengthened. A rotation angle detecting device provided by:

請求項１に記載の回転角度検出装置において、
前記磁束平行化手段は、前記磁束付与手段と前記磁束吸引手段を回転軸を中心とした略扇形形状にすることによって設けられたことを特徴とする回転角度検出装置。The rotation angle detection device according to claim 1,
The rotation angle detecting device, wherein the magnetic flux parallelizing means is provided by forming the magnetic flux applying means and the magnetic flux attraction means into a substantially sector shape about a rotation axis.

請求項１に記載の回転角度検出装置において、
前記磁束平行化手段は、前記磁束付与手段と前記磁束吸引手段をそれぞれ複数の直方体によって構成し、その複数の直方体を回転軸を中心として円弧状に配置することによって設けられたことを特徴とする回転角度検出装置。The rotation angle detection device according to claim 1,
The magnetic flux collimating means is characterized in that the magnetic flux applying means and the magnetic flux attracting means are each constituted by a plurality of rectangular parallelepipeds, and the plurality of rectangular parallelepipeds are arranged in an arc around the rotation axis. Rotation angle detection device.

請求項１〜請求項４のいずれかに記載の回転角度検出装置において、
前記磁束付与手段と前記磁束吸引手段は、回転軸方向に着磁され、前記磁束付与手段と前記磁束吸引手段の着磁方向が逆方向の永久磁石であることを特徴とする回転角度検出装置。The rotation angle detection device according to any one of claims 1 to 4,
The rotation angle detecting device according to claim 1, wherein said magnetic flux applying means and said magnetic flux attracting means are permanent magnets magnetized in a rotation axis direction, and said magnetic flux applying means and said magnetic flux attracting means are magnetized in opposite directions.

請求項５に記載の回転角度検出装置において、
永久磁石によって構成される前記磁束付与手段と前記磁束吸引手段は、
前記磁気検出チップが配置される側とは異なった側において磁性体製よりなるヨークを介して磁気結合されることを特徴とする回転角度検出装置。The rotation angle detection device according to claim 5,
The magnetic flux applying means and the magnetic flux attracting means constituted by a permanent magnet,
A rotation angle detection device, wherein a magnetic coupling is performed via a yoke made of a magnetic material on a side different from a side on which the magnetic detection chip is disposed.

略回転軸上に配置された磁気検出素子と、
この磁気検出素子に対して回転軸方向に距離を隔てて配置されるとともに、回転軸方向から見て前記磁気検出素子の両側に距離を隔てて対向配置され、
回転軸方向の前記磁気検出素子が配置された側に磁束の発生部が向けられる磁束付与磁石、および回転軸方向の前記磁気検出素子が配置された側に磁束の吸引部が向けられて前記磁束付与磁石から放出された磁束を吸引する磁束吸引磁石を備える磁束発生手段と、を具備し、
前記磁束付与磁石と前記磁束吸引磁石は、前記磁気検出素子が配置される側とは異なった側において磁性体製よりなるヨークを介して磁気結合されるものであり、
前記磁気検出素子と前記磁束発生手段の相対回転角度の変化を、前記磁気検出素子を通過する磁束によって検出する回転角度検出装置。A magnetic detection element arranged substantially on the rotation axis,
Along with being arranged at a distance in the rotation axis direction with respect to the magnetic detection element, the magnetic detection element is opposed to each other at a distance on both sides of the magnetic detection element viewed from the rotation axis direction,
A magnetic flux providing magnet having a magnetic flux generation unit directed to the side where the magnetic detection element is disposed in the rotation axis direction, and a magnetic flux attracting unit directed to the side where the magnetic detection element is disposed in the rotation axis direction. Magnetic flux generating means comprising a magnetic flux attracting magnet for attracting magnetic flux emitted from the applying magnet,
The magnetic flux imparting magnet and the magnetic flux attracting magnet are magnetically coupled via a yoke made of a magnetic material on a side different from the side on which the magnetic detection element is arranged,
A rotation angle detection device for detecting a change in a relative rotation angle between the magnetic detection element and the magnetic flux generating means based on a magnetic flux passing through the magnetic detection element.

略回転軸上に配置され、回転軸の直交方向に磁気検出面が所定の角度を隔てて配置された２つの磁気検出素子を有する磁気検出チップと、
この磁気検出チップに対して回転軸方向に距離を隔てて配置されるとともに、回転軸方向から見て前記磁気検出チップの両側に距離を隔てて対向配置され、
回転軸方向の前記磁気検出チップが配置された側に磁束の発生部が向けられる磁束付与磁石、および回転軸方向の前記磁気検出チップが配置された側に磁束の吸引部が向けられて前記磁束付与磁石から放出された磁束を吸引する磁束吸引磁石を備える磁束発生手段と、を具備し、
前記磁束付与磁石と前記磁束吸引磁石は、前記磁気検出チップが配置される側とは異なった側において磁性体製よりなるヨークを介して磁気結合されるものであり、
前記磁気検出チップと前記磁束発生手段の相対回転角度の変化を、前記２つの磁気検出素子を通過する磁束によって検出する回転角度検出装置。A magnetic detection chip having two magnetic detection elements arranged substantially on the rotation axis and having a magnetic detection surface arranged at a predetermined angle in a direction orthogonal to the rotation axis;
Along with the magnetic detection chip is disposed at a distance in the direction of the rotation axis, and is disposed opposite to both sides of the magnetic detection chip at a distance when viewed from the direction of the rotation axis,
A magnetic flux providing magnet having a magnetic flux generation unit directed to the side where the magnetic detection chip is disposed in the rotation axis direction, and a magnetic flux attracting unit directed to the side where the magnetic detection chip is disposed in the rotation axis direction. Magnetic flux generating means comprising a magnetic flux attracting magnet for attracting magnetic flux emitted from the applying magnet,
The magnetic flux imparting magnet and the magnetic flux attracting magnet are magnetically coupled via a yoke made of a magnetic material on a side different from the side on which the magnetic detection chip is arranged,
A rotation angle detection device for detecting a change in a relative rotation angle between the magnetic detection chip and the magnetic flux generating means by a magnetic flux passing through the two magnetic detection elements.