JP4982925B2

JP4982925B2 - Rotation angle detector

Info

Publication number: JP4982925B2
Application number: JP2001146212A
Authority: JP
Inventors: 幸司御池; 清孝笹之内; 正晴牛原; 潤一湯河
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2001-05-16
Filing date: 2001-05-16
Publication date: 2012-07-25
Anticipated expiration: 2021-05-16
Also published as: JP2002340619A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車の車体制御システムなどに用いられる多回転のハンドルの回転角度検出装置に関するものである。
【０００２】
【従来の技術】
従来、自動車用ハンドルのように１回転以上に有限で回転する回転体の回転角度を検出する回転角度検出装置として、特表平１１−５００８２８号公報に開示されているものが知られている。この装置においては、位相差を有する２つの回転体の角度から回転角度を検出している。
【０００３】
【発明が解決しようとする課題】
しかしながら、上述の装置においては、歯車のがたつきなどにより２つの歯車の角度がそれぞれずれた場合、特に装置の動作開始時に大きな測定誤差が発生する可能性があり、また回転角度を算出するにあたり、複雑な計算処理を必要としていた。
【０００４】
本発明はこの課題を解決するためのものであり、大きな誤差を発生することなく、また簡単な計算処理で多回転する回転体の回転角度を高分解能で検出でき、回転体や検出手段の異常検出もでき、温度特性の優れた高信頼性の回転角度検出装置を提供することを目的とするものである。
【０００５】
【課題を解決するための手段】
本発明の請求項１に記載の発明は、多回転可能な外周に歯車を持った第１の回転体と、前記第１の回転体の歯車に連結され第１の回転体より高速に回転する外周に歯車を持った第２の回転体と、前記第２の回転体の回転角度を検出する第１の検出手段と、前記第２の回転体の同軸上に共に回転するウォームギヤに連結され、外周にホイールギヤを持った前記第１の回転体より低速で回転する第３の回転体と、前記第３の回転体の回転角を検出する第２の検出手段とを備え、前記第１の検出手段と第２の検出手段が磁気検出素子であり、各々の磁気検出素子が前記第２，第３の回転体に結合された磁石を走査すると共に、前記第１の検出手段により細かい絶対回転角度を検出し、前記第２の検出手段により粗い絶対回転角度を検出し、前記第２の検出手段により前記第２の回転体の回転数を確定することによって前記第１の回転体の回転角度を検出する回転角度検出装置であって、前記第１，第２，第３の回転体とを組込み後、前記第２の回転体の回転基準と前記第３の回転体の回転基準との差を記憶する不揮発性のメモリを有し、電源投入時毎に前記回転基準の差を補正することを特徴とする回転角度検出装置としたものであり、磁気検出素子と磁石による２つの第１，第２の検出手段によって、非接触で角度検出できると共に、多回転可能な回転体を、大きな誤差を発生することなく、また簡単な計算処理で多回転する回転体の回転角度を算出できるという作用を有する。
さらに、前記第１，第２，第３の回転体とを組込み後、前記第２の回転体の回転基準と前記第３の回転体の回転基準との差を記憶する不揮発性のメモリを有し、電源投入時毎に前記回転基準の差を補正することによって、上述装置に前記第２，第３の回転体を組込む時に、前記第２，第３の回転体に固定された歯車の角度がそれぞれずれた場合でも装置動作時の大きな測定誤差の発生を防止することができるという作用を有する。
【００１０】
本発明の請求項２記載の発明は、請求項１に記載の発明において、前記回転体に結合された磁石の回転角度に対して前記磁気検出素子から出力されるｓｉｎ信号とｃｏｓ信号からｔａｎ信号を算出して前記回転体の回転角度を算出することを特徴とする回転角度検出装置としたものであり、前記検出素子感度の温度ドリフトを相殺することができるという作用を有する。
【００１１】
本発明の請求項３に記載の発明は、請求項１に記載の発明において、前記第２の回転体と前記第３の回転体とを組込み後、前記各磁気検出素子から出力されるｓｉｎ信号とｃｏｓ信号の基準信号を記憶する不揮発性のメモリを有し、電源投入時毎に前記基準信号にて前記ｓｉｎ信号とｃｏｓ信号を補正することを特徴とする回転角度検出装置としたものであり、前記検出素子と前記磁石の相対位置がずれた状態で組み込まれても、装置動作時の大きな測定誤差の発生を防止することができる。
【００１２】
本発明の請求項４に記載の発明は、請求項１ないし３のいずれか１項に記載の発明において、前記第１の検出手段の回転信号と前記第２の検出手段の回転信号より、前記第１の検出手段或いは第２の検出手段の異常を検出することを特徴とする回転角度検出装置としたものであり、前記検出手段が故障しても誤った測定値を回転角度検出装置外に出力することを防止することができる。
【００１３】
本発明の請求項５に記載の発明は、請求項１ないし３のいずれか１項に記載の発明において、第１の検出手段の回転信号と前記第２の検出手段の回転信号より前記第２の回転体あるいは前記第３の回転体の異常を検出することを特徴とする回転角度検出装置としたものであり、前記回転体が故障しても誤った測定値を回転角度検出装置外に出力することを防止することができる。
【００１４】
本発明の請求項６に記載の発明は、請求項１ないし５のいずれか１項に記載の発明において、前記第１の検出手段と前記第２の検出手段により検出された前記第１の回転体の回転角度をシリアル信号として送信する演算回路部を備えたことを特徴とする回転角度検出装置としたものであり、装置内部で角度算出でき外部に通信できるという作用を有する。
【００１５】
本発明の請求項７に記載の発明は、請求項１ないし６のいずれか１項に記載の発明において、前記第１の回転体の角度は自動車の操舵角であり、前記第１の回転体が操舵軸に係合されて前記操舵軸と共に回転する回転角度検出装置としたものであり、少ない部品点数で自動車の絶対操舵角を検出できるという作用を有する。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態について、図１から図６を用いて説明する。
【００１７】
（実施の形態１）
図１は本発明の実施の形態１における回転角度検出装置を示す平面図、図２は同一部切欠正面図、図３は同一部切欠側面図、図４は同装置における第１の回転体１の回転角度と第２の回転体２及び第３の回転体７の回転角度との関係を示す図、図５は同じく第１の回転体１の回転角度と第２の回転体２及び第３の回転体７の回転角度との関係を示す図、図６は第１の検出手段３と第２の検出手段５と演算回路部１４の関係を示すブロック図、図７，図８は第１，第２の検出手段３，５の出力信号を示す図である。
【００１８】
図１ないし図３において、１は外周に歯車がついた第１の回転体、２は外周に歯車がついた第２の回転体であり、第１の回転体１に増速関係で連結されている。３は第２の回転体２の中央部に組み込まれており第２の回転体２とともに回転する磁石４の磁界方向を検出する第１の検出手段（異方性磁気検出素子）、５は第３の回転体７の中央部に組み込まれており第３の回転体７とともに回転する磁石６の磁界方向を検出する第２の検出手段（異方性磁気検出素子）、８は第２の回転体２に固定されておりウォームギヤ９を有する軸であり、ケース１０に設けられた軸受け１２，１３により位置規制されている。ウォームギヤ９は、軸８に固定されており第３の回転体７の外周に切られたホイールギヤと連結されている。第３の回転体７はケース１０に設けられた軸受け１１により位置規制されており、第１の回転体１に対して減速関係にある。
【００１９】
第１の回転体１の歯車は第２の回転体２の歯車と連結されており、第２の回転体２は第１の回転体１が回転すると各歯車の歯数の比による増速比で回転する。第３の回転体７のホイールギヤはウォームギヤ９と連結されており、第２の回転体２が回転すると軸８、ウォームギヤ９が回転しウォームとホイールの減速比で回転する。
【００２０】
図６において、１４はマイクロコンピュータ（演算回路部）であり、第１の検出手段３と第２の検出手段５にＡＭＰ（増幅器）を介して接続されており、それぞれの出力信号をマイクロコンピュータ１４へ入力して回転角度を演算しその結果をシリアル信号として送信する。また、マイクロコンピュータ１４には前記各異方性磁気検出素子３，５から出力されるｓｉｎ信号とｃｏｓ信号の基準信号等を記憶する不揮発性のメモリ（ＥＥＰＲＯＭ）が接続されている。
【００２１】
次に、以上の構成により回転体の回転角度検出方法について説明する。図１において、第１の回転体１が回転したとき、その外周にある歯車と第２の回転体２の外周にある歯車によって第２の回転体２を回転させる。第１の回転体１の歯車の歯数をａ、第２の回転体２の歯車の歯数をｂ、ウォームギヤ９と第３の回転体７の外周に切られたホイールギヤとの減速比をｃとすると、第２の回転体２は第１の回転体１に対してａ／ｂ倍の速さで回転する。第２の回転体２は軸８を回転させ、ウォームギア９も同等の速さで回転する。
【００２２】
次にウォームギヤ９は第３の回転体７を回転させ、第３の回転体７はウォームギヤ９に対してｃ倍の速さで回転する。一方、回転数で見ると、第１の回転体１が１回転すると第２の回転体２はａ／ｂ回転し、第３の回転体７は（ａ／ｂ）＊ｃ回転する。また、この際、歯車の歯数ａ，ｂ及び減速比ｃを適切に選択することにより、第３の回転体７は第１の回転体１よりも十分低速回転し、第２の回転体２は第１の回転体１よりも十分高速回転する。第１の検出手段３は第２の回転体２に組み込まれている磁石４の真下に配置されているため、第２の回転体２が回転すると第１の検出手段３を貫く磁力の方向が変化し、出力が変化する。同様に第２の検出手段５も第３の回転体７が回転すると第２の検出手段５を貫く磁力の方向が変化し、出力は変化する。
【００２３】
さらに、第１の検出手段３と第２の検出手段５の出力を演算回路部１４（マイクロコンピュータ）内のＡ／Ｄコンバータを介して入力する。第２の回転体２が初期位置から何回転目であるかという粗い絶対角度検出を第２の検出手段５の出力から、第１の回転体１の回転角度の細かい絶対角度検出を第１の検出手段３の出力から演算する。
【００２４】
図４でもって、第１，第２，第３の回転体１，２，７の回転角の関係を説明する。ａを４、ｂを１、ｃを１／１２とすると、第１の回転体１が１回転した場合第２の回転体２の回転数は４回転、すなわち第１の回転体１が４５ｄｅｇ回転すると第２の回転体２は１８０ｄｅｇ回転する。
【００２５】
一方、第３の回転体７の回転数は１／１２回転となり、第１の回転体１が２１６０ｄｅｇ回転すると、第３の回転体７は１８０ｄｅｇ回転する。すなわち図１に示すような出力が得られる。第３の回転体７の絶対角によって第２の回転体２の回転数を算出し、更に第２の回転体２の絶対角によって、第１の回転体１の細かい絶対角を検出する。この場合、第１の回転体１が６回転するまでの絶対回転角度の検出が可能である。
【００２６】
次に第１，第２，第３の回転体をケース１０に組み込んだ時、第２の回転体２の回転基準と、第３の回転体７の回転基準とがずれることがある。その状態を図５に示す。第２の回転体２の回転基準を１６で、ずれた第３の回転体７の回転基準を１７で示している。この回転基準のずれが大きいと第２の回転体２の回転数の算出を誤る。すなわち、第１の回転体１の絶対角を＋４５ｄｅｇ或いは−４５ｄｅｇずれた形で算出してしまう。
【００２７】
そこで、前記回転体をケース１０に組み込んだ後、通信ラインを通してこのずれ量を算出するモードにするコードを図６に示すマイクロコンピュータ１４に送信し、回転基準近傍で第１の回転体１を±１回転させ、図５に示す第２の回転体２の回転基準に対する第３の回転体７の絶対回転角ｘを検出し、第３の回転体７の回転基準に対する絶対回転角ｙとの差を図６に示す不揮発性メモリ（ＥＥＰＲＯＭ）１５に記憶する。その後、通信ラインを通してこのずれ量を算出するモードから通常モードにするコードを図６に示すマイクロコンピュータ１４に送信し、その後の電源投入時毎に第３の回転体７の絶対角に、この差（ｘ−ｙ）を補正してから第２の回転体２の回転数の算出を行う。
【００２８】
次に第２の回転体２及び第３の回転体７に固定されている磁石６，７の回転を検出する第１，第２の検出手段（異方性磁気検出素子）３，５からの絶対角算出方法について説明する。また、絶対角算出方法は共通なのでまとめて説明する。
【００２９】
図１において、第２の回転体２が回転すると磁石６も回転する。この磁石６の回転と共に磁界方向も回転し、この磁界方向を第１の検出手段（異方性磁気検出素子）３で検出する。第１の検出手段（異方性磁気検出素子）３からは、この磁界方向の回転角に対してｓｉｎ信号１８とｃｏｓ信号１９を出力する。図７にこれらの出力信号を示す。ｘ軸に第１の回転体１の回転角をとってそれぞれの信号を示している。これらの信号はマイクロコンピュータ（演算回路部）１４に入力されｓｉｎ信号１８とｃｏｓ信号１９よりｔａｎ信号２０を算出する。この時ｓｉｎ信号１８をｃｏｓ信号１９で除算するため、それぞれの感度が周囲温度によって変化しても、それぞれの感度変化は相殺されｔａｎ信号２０より算出される絶対回転角度は周囲温度が変化しても精度が高く算出される。
【００３０】
図７に示すように第２の回転体２は第１の回転体１に対して増速されているので、第１の検出手段３の信号周期は短くなっており、逆に第３の回転体７は第１の回転体１に対して減速されているので第２の検出手段５の信号周期は長くなっている。
【００３１】
次に第２の回転体２の回転角に対する第１の検出手段３の出力を図８に示す。図８からわかるようにｓｉｎ信号１８の基準２１とｃｏｓ信号１９の基準２２との間に差が発生している。この差を補正せずにｔａｎ信号を算出すると絶対回転角が正確に算出できない。そこで、第１，第２，第３の回転体をケース１０に組み込んだ時、通信ラインを通してこれらの基準を算出するモードにするコードを図６に示すマイクロコンピュータ１４に送信し、第２の回転体２が１回転以上するように第１の回転体１を回転させ、ｓｉｎ信号１８及びｃｏｓ信号１９それぞれの最大値、最小値を検出し（最大値＋最小値）／２の値を算出して、それぞれの基準２１，２２として不揮発性メモリ１５に記憶する。
【００３２】
その後、通信ラインを通してこのずれ量を算出するモードから通常モードにするコードを図６に示すマイクロコンピュータ１４に送信し、その後の電源投入時毎に不揮発性メモリ１５から基準２１，２２を読み込み、これらの基準に対するｓｉｎ信号１８及びｃｏｓ信号１９に直してからｔａｎ信号２０を算出して磁石３の絶対回転角を算出する。
【００３３】
一方、第１の検出手段３の信号から算出した絶対回転角が変化しているにもかかわらず、第２の検出手段５の信号から算出した絶対回転角が変化していない場合は、第１の検出手段３または第２の検出手段５或いは第２の回転体２または第３の回転体７に異常が発生しているとして、通信ラインより算出した第１の回転体１の絶対回転角を送信するのではなく、回転角度検出装置の異常を示すコードを送信し、メインシステムの誤動作をさせないようにする。第１の検出手段３の信号から算出した絶対回転角が変化していないのに、第２の検出手段５の信号から算出した絶対回転角が変化している場合も同様のことが言える。
【００３４】
また、第１の回転体１と第２の回転体２、第３の回転体７を連結する回転体の数は一方を第１の回転体１より高速に、もう一方を第１の回転体１より低速に回転するように連結できれば、上述の実施の形態より多くても、少なくてもよい。
【００３５】
なお、本実施の形態においては、第１の回転体１と第３の回転体７の間にある第２の回転体２を利用した細かい絶対角検出を行なうものについて説明したが、図９に示すように第２の回転体３２は別途第１の回転体１に独立して連結させ、この第２の回転体３２を利用して細かい絶対角検出を行なうように構成してもよい。この時、第１の回転体１に対して減速連結する伝達機構が必要であることはいうまでもない。
【００３６】
【発明の効果】
以上のように本発明によれば、少ない部品点数で、大きな誤差を発生することなく、また簡単な計算処理で、温度補正することもなく、多回転する回転体の絶対回転角度を精度よく検出することができる回転角度検出装置を実現できるという有利な効果が得られる。
【図面の簡単な説明】
【図１】本発明の実施の形態１による回転角度検出装置の平面図
【図２】同一部切欠正面図
【図３】同一部切欠側面図
【図４】同装置による第１の回転体１の回転角度と第２の回転体２及び第３の回転体７の回転角度との関係を示す図
【図５】同装置による第１の回転体１の回転角度と第２の回転体２及び第３の回転体７の回転角度との関係を示す図
【図６】同装置による第１の検出手段３と第２の検出手段５と演算回路部１４の関係を示すブロック図
【図７】同装置による第１の回転体１の回転角度に対する第１，第２の検出手段３，５の出力信号を示す波形図
【図８】同装置による第１の回転体１の回転角度に対する第１，第２の検出手段３，５の出力信号を示す波形図
【図９】本発明の実施の形態２による回転角度検出装置の平面図
【符号の説明】
１第１の回転体
２第２の回転体
３第１の検出手段
４磁石
５第２の検出手段
６磁石
７第３の回転体
８軸
９ウォームギヤ
１０ケース
１１軸受け
１２軸受け
１３軸受け
１４マイクロコンピュータ
１５ＥＥＰＲＯＭ
１６第２の回転体の回転基準
１７第３の回転体の回転基準
１８ｓｉｎ信号
１９ｃｏｓ信号
２０ｔａｎ信号
２１ｓｉｎ信号の基準
２２ｃｏｓ信号の基準[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation angle detection device for a multi-rotation handle used in a vehicle body control system of an automobile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a rotation angle detection device that detects a rotation angle of a rotating body that rotates finitely more than one rotation, such as an automobile handle, is known as disclosed in JP-T-11-500828. In this apparatus, the rotation angle is detected from the angle of two rotating bodies having a phase difference.
[0003]
[Problems to be solved by the invention]
However, in the above-described apparatus, when the angles of the two gears are shifted due to gear rattling or the like, a large measurement error may occur particularly at the start of operation of the apparatus, and the rotation angle is calculated. Needed complicated calculation processing.
[0004]
The present invention is intended to solve this problem, and can detect a rotation angle of a rotating body that rotates multiple times with high resolution without generating a large error, and can detect abnormalities in the rotating body and detection means. An object of the present invention is to provide a highly reliable rotation angle detection device that can detect and has excellent temperature characteristics.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, a first rotating body having a gear on an outer periphery capable of multiple rotations and a gear connected to the gear of the first rotating body rotate at a higher speed than the first rotating body. A second rotating body having gears on the outer periphery, first detection means for detecting a rotation angle of the second rotating body, and a worm gear rotating together on the same axis of the second rotating body; A third rotating body rotating at a lower speed than the first rotating body having a wheel gear on the outer periphery; and a second detecting means for detecting a rotation angle of the third rotating body, The detection means and the second detection means are magnetic detection elements, and each magnetic detection element scans a magnet coupled to the second and third rotating bodies, and fine absolute rotation is performed by the first detection means. An angle is detected, a rough absolute rotation angle is detected by the second detection means, and the second A rotational angle detector for detecting a rotation angle of said first rotary member by determining a rotation speed of the second rotary member by detecting means, said first, second, third rotating member Is incorporated, a non-volatile memory for storing the difference between the rotation reference of the second rotating body and the rotation reference of the third rotating body is provided, and the difference of the rotation reference is corrected every time the power is turned on. The rotation angle detecting device is characterized in that the angle can be detected in a non-contact manner by two first and second detection means using a magnetic detection element and a magnet, and a rotating body capable of multi-rotation is large. There is an effect that the rotation angle of the rotating body that rotates multiple times can be calculated without generating an error and with a simple calculation process.
Further, after incorporating the first, second and third rotating bodies, there is a nonvolatile memory for storing a difference between the rotation reference of the second rotating body and the rotation reference of the third rotating body. The angle of the gear fixed to the second and third rotating bodies when the second and third rotating bodies are assembled into the above-mentioned device by correcting the difference in rotation reference every time the power is turned on. Even when they deviate from each other, it is possible to prevent the occurrence of a large measurement error during operation of the apparatus.
[0010]
The invention of claim 2, wherein the present invention is the invention according to claim 1, wherein the sin signal output from the magnetic detecting element with respect to the rotation angle of the coupled magnet rotor and the cos signal from the tan signal The rotation angle detecting device is characterized in that the rotation angle of the rotating body is calculated and has a function of canceling out the temperature drift of the detection element sensitivity.
[0011]
According to a third aspect of the present invention, in the first aspect of the present invention, a sin signal output from each of the magnetic detection elements after the second rotating body and the third rotating body are assembled. And a non-volatile memory for storing a reference signal of the cos signal, and a rotation angle detecting device that corrects the sin signal and the cos signal with the reference signal every time the power is turned on. Even when the detection element and the magnet are incorporated with their relative positions shifted, it is possible to prevent the occurrence of a large measurement error during operation of the apparatus.
[0012]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the rotation signal of the first detection means and the rotation signal of the second detection means The rotation angle detection device is characterized by detecting an abnormality in the first detection means or the second detection means. Even if the detection means fails, an erroneous measurement value is output outside the rotation angle detection device. The output can be prevented.
[0013]
According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the second detection signal is obtained from the rotation signal of the first detection means and the rotation signal of the second detection means. The rotation angle detection device is characterized by detecting an abnormality in the rotation body of the first rotation body or the third rotation body, and an erroneous measurement value is output outside the rotation angle detection device even if the rotation body fails. Can be prevented.
[0014]
The invention according to claim 6 of the present invention is the first rotation detected by the first detection means and the second detection means according to any one of claims 1 to 5. The rotation angle detection apparatus includes an arithmetic circuit unit that transmits the rotation angle of the body as a serial signal, and has an effect that the angle can be calculated inside the apparatus and communicated to the outside.
[0015]
The invention according to claim 7 of the present invention is the invention according to any one of claims 1 to 6 , wherein the angle of the first rotating body is a steering angle of an automobile, and the first rotating body. Is a rotation angle detection device that is engaged with the steering shaft and rotates together with the steering shaft, and has the effect that the absolute steering angle of the automobile can be detected with a small number of parts.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0017]
(Embodiment 1)
FIG. 1 is a plan view showing a rotation angle detection device according to Embodiment 1 of the present invention, FIG. 2 is a front view of the same part, FIG. 3 is a side view of the same part, and FIG. 4 is a first rotating body 1 in the same device. FIG. 5 is a diagram showing the relationship between the rotation angle of the first rotation body 2 and the rotation angles of the second rotation body 2 and the third rotation body 7, and FIG. FIG. 6 is a block diagram showing the relationship between the first detection means 3, the second detection means 5, and the arithmetic circuit unit 14, and FIGS. FIG. 5 is a diagram showing output signals of second detection means 3 and 5.
[0018]
In FIG. 1 to FIG. 3, reference numeral 1 denotes a first rotating body with a gear on its outer periphery, and 2 denotes a second rotating body with a gear on its outer periphery, which is connected to the first rotating body 1 in a speed increasing relationship. ing. Reference numeral 3 denotes a first detection means (anisotropic magnetic detection element) for detecting the magnetic field direction of the magnet 4 which is incorporated in the central portion of the second rotary body 2 and rotates together with the second rotary body 2. 3 is a second detection means (anisotropic magnetic detection element) for detecting the magnetic field direction of the magnet 6 incorporated in the central portion of the third rotary body 7 and rotates together with the third rotary body 7, and 8 is the second rotation. The shaft is fixed to the body 2 and has a worm gear 9, and its position is restricted by bearings 12 and 13 provided on the case 10. The worm gear 9 is fixed to the shaft 8 and connected to a wheel gear cut on the outer periphery of the third rotating body 7. The position of the third rotating body 7 is restricted by a bearing 11 provided in the case 10 and is in a deceleration relationship with respect to the first rotating body 1.
[0019]
The gear of the first rotating body 1 is connected to the gear of the second rotating body 2, and the second rotating body 2 is a speed increasing ratio based on the ratio of the number of teeth of each gear when the first rotating body 1 rotates. Rotate with. The wheel gear of the third rotating body 7 is connected to the worm gear 9, and when the second rotating body 2 rotates, the shaft 8 and the worm gear 9 rotate to rotate at the reduction ratio of the worm and the wheel.
[0020]
In FIG. 6, reference numeral 14 denotes a microcomputer (arithmetic circuit unit), which is connected to the first detection means 3 and the second detection means 5 via an AMP (amplifier), and outputs the respective output signals to the microcomputer 14. To calculate the rotation angle and transmit the result as a serial signal. The microcomputer 14 is connected to a nonvolatile memory (EEPROM) for storing a sin signal output from each of the anisotropic magnetic detection elements 3 and 5, a reference signal for the cos signal, and the like.
[0021]
Next, a method for detecting the rotation angle of the rotating body with the above configuration will be described. In FIG. 1, when the first rotating body 1 rotates, the second rotating body 2 is rotated by a gear on the outer periphery of the first rotating body 1 and a gear on the outer periphery of the second rotating body 2. The number of teeth of the gear of the first rotating body 1 is a, the number of teeth of the gear of the second rotating body 2 is b, and the reduction ratio between the worm gear 9 and the wheel gear cut on the outer periphery of the third rotating body 7 is Assuming c, the second rotating body 2 rotates at a speed a / b times that of the first rotating body 1. The second rotating body 2 rotates the shaft 8 and the worm gear 9 also rotates at the same speed.
[0022]
Then the worm gear 9 rotates the third rotating member 7, a third rotary member 7 is rotated at a speed of c times the worm gear 9. On the other hand, in terms of the number of rotations, when the first rotating body 1 rotates once, the second rotating body 2 rotates a / b and the third rotating body 7 rotates (a / b) * c. At this time, by appropriately selecting the number of gear teeth a and b and the reduction ratio c, the third rotating body 7 rotates at a sufficiently lower speed than the first rotating body 1, and the second rotating body 2. Rotates sufficiently faster than the first rotating body 1. Since the first detection means 3 is disposed directly below the magnet 4 incorporated in the second rotating body 2, the direction of the magnetic force penetrating the first detection means 3 is changed when the second rotating body 2 rotates. Change and the output changes. Similarly, when the third rotating body 7 rotates in the second detection means 5, the direction of the magnetic force passing through the second detection means 5 changes and the output changes.
[0023]
Further, the outputs of the first detection means 3 and the second detection means 5 are inputted via an A / D converter in the arithmetic circuit section 14 (microcomputer). From the output of the second detection means 5, coarse absolute angle detection of how many rotations the second rotator 2 is from the initial position is performed. From the output of the second detection means 5, fine absolute angle detection of the first rotator 1 is performed. It calculates from the output of the detection means 3.
[0024]
With reference to FIG. 4, the relationship between the rotation angles of the first, second, and third rotating bodies 1, 2, and 7 will be described. Assuming that a is 4, b is 1, and c is 1/12, when the first rotating body 1 makes one rotation, the second rotating body 2 has four rotations, that is, the first rotating body 1 rotates 45 degrees. Then, the second rotating body 2 rotates 180 degrees.
[0025]
On the other hand, the rotation speed of the third rotating body 7 is 1/12, and when the first rotating body 1 rotates 2160 degrees, the third rotating body 7 rotates 180 degrees. That is, an output as shown in FIG. 1 is obtained. The number of rotations of the second rotating body 2 is calculated from the absolute angle of the third rotating body 7, and the fine absolute angle of the first rotating body 1 is detected from the absolute angle of the second rotating body 2. In this case, it is possible to detect the absolute rotation angle until the first rotating body 1 rotates six times.
[0026]
Next, when the first, second, and third rotating bodies are assembled in the case 10, the rotation reference of the second rotating body 2 and the rotation reference of the third rotating body 7 may deviate. The state is shown in FIG. The rotation reference of the second rotating body 2 is indicated by 16, and the rotation reference of the shifted third rotating body 7 is indicated by 17. If the deviation of the rotation reference is large, the calculation of the rotation speed of the second rotating body 2 is erroneous. That is, the absolute angle of the first rotating body 1 is calculated in a form deviated by +45 deg or −45 deg.
[0027]
Therefore, after incorporating the rotating body into the case 10, a code for setting the mode for calculating the deviation amount through the communication line is transmitted to the microcomputer 14 shown in FIG. The absolute rotation angle x of the third rotating body 7 with respect to the rotation reference of the second rotating body 2 shown in FIG. 5 is detected, and the difference from the absolute rotation angle y with respect to the rotation reference of the third rotating body 7 is detected. Is stored in a non-volatile memory (EEPROM) 15 shown in FIG. Thereafter, a code for switching from the mode for calculating the deviation amount to the normal mode through the communication line is transmitted to the microcomputer 14 shown in FIG. 6, and this difference is added to the absolute angle of the third rotating body 7 every time the power is turned on. After correcting (xy), the rotational speed of the second rotating body 2 is calculated.
[0028]
Next, from the first and second detection means (anisotropic magnetic detection elements) 3 and 5 for detecting the rotation of the magnets 6 and 7 fixed to the second rotating body 2 and the third rotating body 7. An absolute angle calculation method will be described. Since the absolute angle calculation method is common, it will be described together.
[0029]
In FIG. 1, when the second rotating body 2 rotates, the magnet 6 also rotates. The direction of the magnetic field also rotates with the rotation of the magnet 6, and this magnetic field direction is detected by the first detection means (anisotropic magnetic detection element) 3. The first detection means (anisotropic magnetic detection element) 3 outputs a sin signal 18 and a cos signal 19 with respect to the rotation angle in the magnetic field direction. FIG. 7 shows these output signals. Respective signals are shown by taking the rotation angle of the first rotating body 1 on the x-axis. These signals are input to a microcomputer (arithmetic circuit unit) 14 and a tan signal 20 is calculated from a sin signal 18 and a cos signal 19. At this time, since the sin signal 18 is divided by the cos signal 19, even if each sensitivity changes depending on the ambient temperature, each sensitivity change is canceled out, and the absolute rotation angle calculated from the tan signal 20 changes the ambient temperature. Is calculated with high accuracy.
[0030]
As shown in FIG. 7, since the speed of the second rotating body 2 is increased with respect to the first rotating body 1, the signal cycle of the first detecting means 3 is shortened, and conversely the third rotation Since the body 7 is decelerated with respect to the first rotating body 1, the signal period of the second detection means 5 is long.
[0031]
Next, the output of the first detection means 3 with respect to the rotation angle of the second rotating body 2 is shown in FIG. As can be seen from FIG. 8, there is a difference between the reference 21 of the sin signal 18 and the reference 22 of the cos signal 19. If the tan signal is calculated without correcting this difference, the absolute rotation angle cannot be calculated accurately. Therefore, when the first, second, and third rotating bodies are incorporated in the case 10, a code for setting these standards to be calculated through the communication line is transmitted to the microcomputer 14 shown in FIG. The first rotating body 1 is rotated so that the body 2 makes one rotation or more, and the maximum and minimum values of the sin signal 18 and the cos signal 19 are detected (maximum value + minimum value) / 2. And stored in the nonvolatile memory 15 as the respective standards 21 and 22.
[0032]
Thereafter, a code for switching from the mode for calculating the amount of deviation through the communication line to the normal mode is transmitted to the microcomputer 14 shown in FIG. 6, and the references 21 and 22 are read from the nonvolatile memory 15 every time the power is turned on. The tan signal 20 is calculated after correcting the sin signal 18 and the cos signal 19 with respect to the reference, and the absolute rotation angle of the magnet 3 is calculated.
[0033]
On the other hand, if the absolute rotation angle calculated from the signal of the second detection means 5 does not change even though the absolute rotation angle calculated from the signal of the first detection means 3 has changed, the first Assuming that an abnormality has occurred in the detecting means 3 or the second detecting means 5 or the second rotating body 2 or the third rotating body 7, the absolute rotation angle of the first rotating body 1 calculated from the communication line is calculated. Instead of transmitting, a code indicating an abnormality of the rotation angle detection device is transmitted so that the main system does not malfunction. The same can be said for the case where the absolute rotation angle calculated from the signal of the second detection means 5 is changed although the absolute rotation angle calculated from the signal of the first detection means 3 is not changed.
[0034]
In addition, the number of rotating bodies connecting the first rotating body 1, the second rotating body 2, and the third rotating body 7 is higher than that of the first rotating body 1, and the other is the first rotating body. As long as it can connect so that it may rotate at low speed from 1, it may be more or less than the above-mentioned embodiment.
[0035]
Although the present embodiment has been described with reference to performing fine absolute angle detection using the second rotating body 2 between the first rotating body 1 and the third rotating body 7, FIG. As shown, the second rotating body 32 may be separately connected to the first rotating body 1 separately, and fine absolute angle detection may be performed using the second rotating body 32. At this time, needless to say, a transmission mechanism for decelerating connection to the first rotating body 1 is necessary.
[0036]
【Effect of the invention】
As described above, according to the present invention, the absolute rotation angle of a rotating body that rotates multiple times can be accurately detected with a small number of parts, without generating a large error, and with simple calculation processing and without temperature correction. An advantageous effect is obtained that a rotation angle detection device capable of performing the above can be realized.
[Brief description of the drawings]
FIG. 1 is a plan view of a rotation angle detection device according to a first embodiment of the present invention. FIG. 2 is a front view of the same part cut out. FIG. 3 is a side view of the same part cut out. FIG. 5 is a diagram showing the relationship between the rotation angle of the first rotation body 1 and the rotation angles of the second rotation body 2 and the third rotation body 7; FIG. 6 is a block diagram showing the relationship between the first detecting means 3, the second detecting means 5 and the arithmetic circuit unit 14 according to the same apparatus. FIG. 8 is a waveform diagram showing output signals of the first and second detection means 3 and 5 with respect to the rotation angle of the first rotating body 1 by the apparatus. FIG. 9 is a waveform diagram showing output signals of the second detection means 3 and 5. FIG. 9 is a plan view of the rotation angle detection device according to the second embodiment of the present invention. Description of the issue]
DESCRIPTION OF SYMBOLS 1 1st rotary body 2 2nd rotary body 3 1st detection means 4 Magnet 5 2nd detection means 6 Magnet 7 3rd rotary body 8 Shaft 9 Worm gear 10 Case 11 Bearing 12 Bearing 13 Bearing 14 Microcomputer 15 EEPROM
16 Rotation reference 17 of the second rotator 17 Rotation reference of the third rotator 18 sin signal 19 cos signal 20 tan signal 21 sin signal reference 22 cos signal reference

Claims

A first rotating body having a gear on an outer periphery capable of multiple rotation; a second rotating body having a gear on the outer periphery connected to the gear of the first rotating body and rotating at a higher speed than the first rotating body; The first detection means for detecting the rotation angle of the second rotating body and the first rotation having a wheel gear on the outer periphery, coupled to a worm gear rotating coaxially with the second rotating body. A third rotating body that rotates at a lower speed than the body, and a second detecting means that detects a rotation angle of the third rotating body, wherein the first detecting means and the second detecting means are magnetic detection elements. Each magnetic detection element scans a magnet coupled to the second and third rotating bodies, detects a fine absolute rotation angle with the first detection means, and detects the absolute rotation angle with the second detection means. A rough absolute rotation angle is detected, and the second rotating body is detected by the second detecting means. A rotational angle detector for detecting a rotation angle of said first rotary member by determining the rotational speed, the first, second, after integration and the third rotating member, said second rotary member A rotation angle detecting device comprising a nonvolatile memory for storing a difference between a rotation reference of the third rotation body and a rotation reference of the third rotating body, and correcting the difference of the rotation reference every time the power is turned on .

Each magnetic detection element outputs a sin signal and a cos signal for the rotation angle of the magnet coupled to the rotating body, calculates a tan signal from these signals, and then calculates the rotation angle of the rotating body. The rotation angle detection device according to claim 1 .

After incorporating the second rotating body and the third rotating body, a non-volatile memory for storing a sin signal and a cos signal reference signal output from each of the magnetic detection elements is provided. The rotation angle detection device according to claim 1, wherein the sin signal and the cos signal are corrected by the respective reference signals every time.

Any one of claims 1 to 3, characterized in that detecting an abnormality in the first detection means or second detection means by the rotation signal of the rotation signal and the second detection means of said first detection means The rotation angle detection device according to one.

Any of claims 1 to 3, characterized in that detecting the first of said second rotary member or the third rotating member from the rotation signal of the rotation signal and said second detection means detecting means abnormal The rotation angle detection device according to claim 1.

Any of claims 1 to 5, characterized in that an arithmetic circuit unit which transmits the detected rotation angle of the first rotary member by said first detection means and the second detecting means as a serial signal The rotation angle detection device according to claim 1.

The rotation according to any one of claims 1 to 6 , wherein the angle of the first rotating body is a steering angle of an automobile, and the first rotating body is engaged with a steering shaft and rotates together with the steering shaft. Angle detection device.