JP3737011B2

JP3737011B2 - Torque sensor

Info

Publication number: JP3737011B2
Application number: JP2000082777A
Authority: JP
Inventors: 真史久世; 哲也村上; 周三平櫛
Original assignee: Koyo Seiko Co Ltd
Current assignee: Koyo Seiko Co Ltd
Priority date: 2000-03-23
Filing date: 2000-03-23
Publication date: 2006-01-18
Anticipated expiration: 2020-03-23
Also published as: JP2001272288A

Description

【０００１】
【発明の属する技術分野】
本発明は、例えば操舵トルクに応じた操舵補助力を付与するパワーステアリング装置において、その操舵トルクを検出するのに適したトルクセンサに関する。
【０００２】
【従来の技術】
例えば車両のパワーステアリング装置においては、ステアリングホイールの回転をステアリングシャフトを介して車輪に伝達する際、そのステアリングシャフトにより伝達されるトルクをトルクセンサにより検出し、その検出トルクの大きさに応じて操舵補助力を付与している。
【０００３】
そのトルクセンサとして、トルク変化に応じた磁気抵抗の変動に基づきトルクを検出するものが従来から用いられている。その検出原理に基づくトルクセンサは、第１シャフトと、この第１シャフトに弾性的に相対回転可能に連結された第２シャフトと、第１シャフトに固定される磁性材製の第１検出リングと、第２シャフトに固定される磁性材製の第２検出リングと、両検出リングの対向間を覆うコイルとを備えている。各検出リングの端面に複数の歯が周方向に沿って設けられ、一方の検出リングの歯と他方の検出リングの歯とはエアギャップを介して対向する。このトルクセンサにおいては、両シャフトによるトルク伝達により両検出リングが相対回転する時、一方の検出リングの歯と他方の検出リングの歯との対向面積が変化する。その面積変化により、両検出リングの歯の間のエアギャップを通過する上記コイルの発生磁束に対する磁気抵抗が変化する。その磁気抵抗の変化に基づき両シャフトにより伝達されるトルクが検出される。さらに、温度変化によるトルク検出値の変動を補償するため、上記コイルと同一仕様の磁束発生用コイルと、その磁束に対する磁気抵抗の温度変化による変化を検出するための磁気回路とが設けられている。
【０００４】
【発明が解決しようとする課題】
上記従来のトルクセンサは、両シャフトから径方向に張り出す第１、第２検出リングの外方をコイルにより覆うため、径方向寸法が大きくなる。また、組み立て誤差や加工誤差の累積による検出精度の低下が問題になる。また、検出感度を増大するためには各検出リングに設ける歯の数を多くする必要があるが、そうすると各検出リングの各シャフトからの張り出し寸法が大きなり、より大型化する。さらに、温度変化による検出値変動の補償のためだけに専用の磁気回路が必要になり、シャフト軸方向寸法が大きくなると共に構造が複雑になって製造コストが増大する。
【０００５】
本発明は、上記問題を解決することのできるトルクセンサを提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明のトルクセンサは、第１シャフトと、その第１シャフトに同軸心かつ弾性的に相対回転可能に連結される第２シャフトと、その第１シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する導電性非磁性材製の規制側回転板と、その第２シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する磁性材製の通過側回転板と、シャフト軸心まわりに巻かれる導線により構成されると共に、交番磁界を生じるように磁束を発生させるコイルとを備え、その規制側回転板と通過側回転板とコイルとは、シャフト軸方向において並列するように配置され、その規制側回転板は、その通過側回転板とコイルとの間に配置され、その規制側回転板と通過側回転板とは、そのコイルの発生磁束の通過位置に配置され、その規制側回転板に規制側開口が形成され、その通過側回転板に通過側開口が形成され、シャフト軸方向において、その規制側開口と通過側回転板との重なり面積が両シャフトの相対回転に応じて変化するように、その規制側開口と通過側開口とは両シャフトの相対回転に応じて重なり面積が変化するように相対配置され、その重なり面積の変化に応じた通過側回転板の通過磁束の変化に基づき、両シャフトにより伝達されるトルクが検出される。
その通過側回転板を構成する磁性材としては、トルクセンサを構成する上で必要な磁気特性に優れた例えば軟質磁性金属材料や磁性樹脂材料を用いることができる。その規制側回転板を構成する導電性を有する非磁性材としては、アルミニウム等の導電性に優れると共に透磁率の小さい常磁性体を用いることができる。
上記構成においては、トルク伝達時における両シャフトの相対回転により、規制側回転板の規制側開口と通過側回転板の通過側開口との重なり状態が変化する。これにより、その規制側開口と通過側回転板との重なり面積が両シャフトの相対回転に応じて変化する。その通過側回転板は磁性材製であり、その規制側回転板は非磁性材製であるので、その重なり面積の変化によって通過側回転板の通過磁束が変化する。また、そのコイルの磁束発生に基づき生じる交番磁界内で規制側回転板に生じる渦電流によっても、その通過側回転板に至る磁束が遮られる。これにより、その通過側回転板の通過磁束を、その重なり面積の変化に応じて変化させることができる。その面積変化は伝達トルクに対応する両シャフトの相対回転に対応することから、その磁束変化に基づき両シャフトにより伝達されるトルクを検出できる。
上記構成によれば、コイルを規制側回転板と通過側回転板と共にシャフト軸方向において並列するように配置できるので、径方向寸法を小さくできる。
【０００７】
本発明のトルクセンサは、第１シャフトと、その第１シャフトに同軸心かつ弾性的に相対回転可能に連結される第２シャフトと、その第１シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する導電性非磁性材製の第１規制側回転板と、その第２シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する磁性材製の第１通過側回転板と、その第１シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する磁性材製の第２通過側回転板と、その第２シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する第２規制側回転板と、シャフト軸心まわりに巻かれる導線により構成されると共に、交番磁界を生じるように磁束を発生させる互いに同一仕様の第１、第２コイルとを備え、両規制側回転板と両通過側回転板と両コイルとは、シャフト軸方向において並列するように配置され、両コイルの間に両規制側回転板と両通過側回転板とが配置され、両規制側回転板の間に両通過側回転板が配置され、その第１コイルと第１通過側回転板との間に第１規制側回転板と第２通過側回転板が配置され、その第２コイルと第２通過側回転板との間に第２規制側回転板と第１通過側回転板が配置され、その第１規制側回転板に第１規制側開口が形成され、その第２規制側回転板に第２規制側開口が形成され、その第１通過側回転板に、第１通過側開口と、その第２規制側開口と第１通過側回転板とのシャフト軸方向における重なり阻止用開口とが形成され、その第２通過側回転板に、第２通過側開口と、その第１規制側開口と第２通過側回転板とのシャフト軸方向における重なり阻止用開口とが形成され、その第１規制側開口と、第２通過側回転板の重なり阻止用開口と、第１通過側回転板とは、その第１コイルの発生磁束の通過位置に配置され、その第２規制側開口と、第１通過側回転板の重なり阻止用開口と、第２通過側回転板は、その第２コイルの発生磁束の通過位置に配置され、シャフト軸方向において、その第１規制側開口と第１通過側回転板との重なり面積が、両シャフトが一方向に相対回転する時は増加し他方向に相対回転する時は減少するように、その第１規制側開口と第１通過側開口とは相対配置され、シャフト軸方向において、その第２規制側開口と第２通過側回転板との重なり面積が、両シャフトが一方向に相対回転する時は減少し他方向に相対回転する時は増加するように、その第２規制側開口と第２通過側開口とは相対配置され、両シャフトが相対回転していない検出原点位置にある時、その第１規制側開口と第１通過側回転板との重なり面積と、その第２規制側開口と第２通過側回転板との重なり面積とは互いに等しくされ、両シャフトの相対回転時において、その第１規制側開口と第１通過側回転板との重なり面積の変化の絶対値と、その第２規制側開口と第２通過側回転板との重なり面積の変化の絶対値とは互いに等しくされ、その第１規制側開口と第１通過側回転板との重なり面積の変化に応じた第１通過側回転板の通過磁束の変化と、その第２規制側開口と第２通過側回転板との重なり面積の変化に応じた第２通過側回転板の通過磁束の変化との差に基づき、両シャフトにより伝達されるトルクが検出されるのが好ましい。
この構成によれば、その第１規制側開口と第１通過側回転板との重なり面積と、第２規制側開口と第２通過側回転板との重なり面積とは、両シャフトが相対回転していない検出原点位置にある時は互いに等しく、両シャフトの相対回転時は一方が増加すると共に他方が減少し、その変化の絶対値は互いに等しい。よって、その第１規制側開口と第１通過側回転板との重なり面積の変化に応じた第１通過側回転板の通過磁束変化と、第２規制側開口と第２通過側回転板との重なり面積の変化に応じた第２通過側回転板の通過磁束変化との差に基づき、両シャフトにより伝達されるトルクを検出し、トルク検出感度を増大できる。しかも、温度が変動した場合、第１通過側回転板を通過する磁束と、第２通過側回転板を通過する磁束とは同じだけ変化するので、両通過磁束変化の差に基づきトルクを検出することで温度変動による検出トルクの変動を相殺できる。よって、検出感度を向上すると同時に温度変化による検出値変動の補償ができ、構造の簡単化とコスト低減を図ることができる。
【０００８】
本発明のトルクセンサは、１シャフトと、その第１シャフトに同軸心かつ弾性的に相対回転可能に連結される第２シャフトと、その第１シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する導電性非磁性材製の第１規制側回転板と、その第１シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する第２規制側回転板と、その第２シャフトと同行回転可能、且つ、シャフト軸方向に直交する表裏面を有する磁性材製の通過側回転板と、シャフト軸心まわりに巻かれる導線により構成されると共に、交番磁界を生じるように磁束を発生させる互いに同一仕様の第１、第２コイルとを備え、両規制側回転板と通過側回転板と両コイルとは、シャフト軸方向において並列するように配置され、両コイルの間に両規制側回転板と通過側回転板とが配置され、両規制側回転板の間に通過側回転板が配置され、その第１規制側回転板に第１規制側開口が形成され、その第２規制側回転板に第２規制側開口が形成され、その通過側回転板に通過側開口が形成され、その第１規制側開口は、その第１コイルの発生磁束の通過位置に配置され、その第２規制側開口は、その第２コイルの発生磁束の通過位置に配置され、その通過側回転板は、両コイルの発生磁束の通過位置に配置され、その第２規制側開口と通過側回転板は、その第２コイルの発生磁束の通過位置に配置され、シャフト軸方向において、その第１規制側開口と通過側回転板との重なり面積が、両シャフトが一方向に相対回転する時は増加し他方向に相対回転する時は減少するように、その第１規制側開口と通過側開口とは相対配置され、シャフト軸方向において、その第２規制側開口と通過側回転板との重なり面積が、両シャフトが一方向に相対回転する時は減少し他方向に相対回転する時は増加するように、その第２規制側開口と通過側開口とは相対配置され、両シャフトが相対回転していない検出原点位置にある時、その第１規制側開口と通過側回転板との重なり面積と、その第２規制側開口と通過側回転板との重なり面積とは互いに等しくされ、両シャフトの相対回転時において、その第１規制側開口と通過側回転板との重なり面積の変化の絶対値と、その第２規制側開口と通過側回転板との重なり面積の変化の絶対値とは互いに等しくされ、その第１規制側開口と通過側回転板との重なり面積の変化に応じた通過側回転板の通過磁束の変化と、その第２規制側開口と通過側回転板との重なり面積の変化に応じた通過側回転板の通過磁束の変化との差に基づき、両シャフトにより伝達されるトルクが検出されるのが好ましい。
この構成によれば、その第１規制側開口と通過側回転板との重なり面積と、第２規制側開口と通過側回転板との重なり面積とは、両シャフトが相対回転していない検出原点位置にある時は互いに等しく、両シャフトの相対回転時は一方が増加すると共に他方が減少し、その変化の絶対値は互いに等しい。よって、その第１規制側開口と通過側回転板との重なり面積の変化に応じた通過側回転板の通過磁束変化と、第２規制側開口と通過側回転板との重なり面積の変化に応じた通過側回転板の通過磁束変化との差に基づき、両シャフトにより伝達されるトルクを検出し、トルク検出感度を増大できる。しかも、温度が変動した場合、第１規制側開口を介して通過側回転板を通過する磁束と、第２規制側開口を介して通過側回転板を通過する磁束とは同じだけ変化するので、両通過磁束変化の差に基づきトルクを検出することで温度変動による検出トルクの変動を相殺できる。よって、検出感度を向上すると同時に温度変化による検出値変動の補償ができ、構造の簡単化とコスト低減を図ることができる。
【０００９】
シャフト径方向において、前記コイルの厚さ寸法は各開口の寸法未満とされると共に、各開口の内外周間に前記コイルの内外周が配置されているのが好ましい。これにより、シャフト、回転板、およびコイルの径方向における相対位置が、製造公差や組み立て公差により変動しても、開口をコイルの発生磁束の通過位置に配置できる。よって、その通過側回転板の通過磁束の公差による変動をなくし、検出精度の低下を防止できる。
さらに、前記コイルを保持する磁性材製のコイルホルダーを備え、そのコイルホルダーは、そのコイルの外周側を囲む筒状の外周部分と、そのコイルの内周側を囲む筒状の内周部分と、その外周部分と内周部分における前記回転板から離れた側の一端部を連結する部分とを有し、シャフト径方向において、シャフト軸心から前記コイルホルダー内周端までの距離は、シャフト軸心から各開口内周端までの距離未満とされ、シャフト径方向において、シャフト軸心から各回転板の外周端までの距離は、シャフト軸心から前記コイルホルダーの外周端までの距離未満とされているのが好ましい。
これにより、確実に開口と通過側回転板をコイルの発生磁束の通過位置に配置できる。通過側回転板の通過磁束の公差による変動をなくすことができる。
【００１０】
各開口は、シャフト径方向に沿う一対の縁と両シャフトの軸心を中心とする円周に沿う一対の縁とを有する４辺形に沿う形状を有するのが好ましい。
これにより、両シャフトが一方向に相対回転した時と、他方向に相対回転した時の何れの場合にも、その相対回転量に応じたトルクを検出できる。
【００１１】
各回転板は両シャフトと同軸心の円板状とされ、各開口は、各回転板にシャフト周方向における間隔をおいて並列するように複数形成されているのが好ましい。これにより、大型化することなくトルク検出感度を向上することができる。
【００１２】
【発明の実施の形態】
図１〜図６に示す第１実施形態のトルクセンサ１は、車両のパワーステアリング装置における操舵トルクを検出する。そのトルクセンサ１は、ハウジング２と、第１シャフト３と、第２シャフト４とを備えている。その第１シャフト３は、軸受５を介してハウジング２により支持され、ブッシュ６を介して第２シャフト４の一端に形成された凹部４ａの内周により支持される。その第２シャフト４は、軸受７を介してハウジング２により支持される。その検出トルクに応じて操舵補助力が付与される。
【００１３】
その第１シャフト３に形成された軸方向孔３ａと、その第２シャフト４の凹部４ａとにトーションバー８が挿入されている。そのトーションバー８の一端はピン９により第１シャフト３に同行回転するように連結され、他端はセレーション１０を介して第２シャフト４に同行回転するように連結されている。これにより、その第２シャフト４は、第１シャフト３と同軸心に配置されると共に、第１シャフト３に弾性的に相対回転可能に連結されている。その第１シャフト３の一端側はステアリングホイール（図示省略）に接続され、その第２シャフト４の他端側は例えばラックピニオン式ステアリングギア等のステアリングギアに接続される。これにより、操舵のためのステアリングホイールの回転が第１、第２シャフト３、４を介して車輪に伝達され、操舵角が変化する。
【００１４】
その第１シャフト３は、シャフト軸方向に直交する表裏面を有する円板状の第１規制側回転板１１に、同軸心に同行回転するように連結されている。本実施形態では、その第１規制側回転板１１は筒体１３と一体的に形成され、その筒体１３が後述の筒体１４′を介して第１シャフト３の外周に圧入されることで第１シャフト３と同行回転するが、その第１規制側回転板１１と第１シャフト３との連結手段は特に限定されない。この第１規制側回転板１１は、アルミニウム等の導電性を有する非磁性材製とされている。
【００１５】
その第２シャフト４は、シャフト軸方向に直交する表裏面を有する円板状の第１通過側回転板１２に、同軸心に同行回転するように連結されている。本実施形態では、その第１通過側回転板１２は筒体１４と一体的に形成され、その筒体１４が第２シャフト４の外周に圧入されることで第２シャフト４と同行回転するが、その第１通過側回転板１２と第２シャフト４との連結手段は特に限定されない。この第１通過側回転板１２は、軟質磁性金属材料等の磁性材製とされている。
【００１６】
その第１シャフト３は、シャフト軸方向に直交する表裏面を有する円板状の第２通過側回転板１２′に、同軸心に同行回転するように連結されている。本実施形態では、その第２通過側回転板１２′は筒体１４′と一体的に形成され、その筒体１４′が第１シャフト３の外周に圧入されることで第１シャフト３と同行回転するが、その第２通過側回転板１２′と第１シャフト３との連結手段は特に限定されない。この第２通過側回転板１２′は、軟質磁性金属材料等の磁性材製とされている。
【００１７】
その第２シャフト４は、シャフト軸方向に直交する表裏面を有する円板状の第２規制側回転板１１′に、同軸心に同行回転するように連結されている。本実施形態では、その第２規制側回転板１１′は筒体１３′と一体的に形成され、その筒体１３′が上記筒体１４を介して第２シャフト４の外周に圧入されることで第２シャフト４と同行回転するが、その第２規制側回転板１１′と第２シャフト４との連結手段は特に限定されない。この第２規制側回転板１１′は、アルミニウム等の導電性を有する非磁性材製とされている。各回転板１１、１１′、１２、１２′の形状、寸法は同一とされている。
【００１８】
そのハウジング２の内周に、磁性材製の第１コイルホルダー３１と磁性材製の第２コイルホルダー３２とが挿入されている。図２に示すように、各コイルホルダー３１、３２は、円筒状の外周部分３１ａ、３２ａと、円筒状の内周部分３１ｂ、３２ｂと、その外周部分３１ａ、３２ａと内周部分３１ｂ、３２ｂにおける一端部を連結する円環部分３１ｃ、３２ｃとから構成される。各コイルホルダー３１、３２は、ハウジング２の内周に形成される段差２ａと、ハウジング２の内周に嵌め合わされる止め輪５３とにより、板バネ５４とスペーサ５５とを介して挟み込まれ、これによりハウジング２に固定される。各コイルホルダー３１、３２はシャフト３、４の外周を隙間を介して囲むように配置される。
【００１９】
その第１コイルホルダー３１により第１コイル３３が保持され、その第２コイルホルダー３２により第２コイル３４が保持される。すなわち、各コイルホルダー３１、３２は、各コイル３３、３４の外周側を外周部分３１ａ、３２ａにより囲み、各コイル３３、３４の内周側を内周部分３１ｂ、３２ｂにより囲む。両コイル３３、３４は同一仕様であり、絶縁材製のボビン３６、３７にシャフト軸心まわりに巻かれる導線３３ａ、３４ａにより構成され、後述のようにトルク検出回路を構成し、交番磁界を生じるように磁束を発生させる。
【００２０】
両規制側回転板１１、、１１′と両通過側回転板１２、１２′と両コイル３３、３４とは、シャフト軸方向において並列するように配置される。両コイル３３、３４の間に両規制側回転板１１、、１１′と両通過側回転板１２、１２′とが配置され、両規制側回転板１１、、１１′の間に両通過側回転板１２、１２′が配置され、その第１コイル３３と第１通過側回転板１２との間に第１規制側回転板１１と第２通過側回転板１２′が配置され、その第２コイル３４と第２通過側回転板１２′との間に第２規制側回転板１１′と第１通過側回転板１２が配置される。各コイルホルダー３１、３２の円環部分３１ｃ、３２ｃは、外周部分３１ａ、３２ａと内周部分３１ｂ、３２ｂにおける回転板１１、１２から離れた側の一端部を連結する。本実施形態では、その第１コイルホルダー３１と第１規制側回転板１１との間、第１通過側回転板１２と第２通過側回転板１２′との間、第２コイルホルダー３２と第２規制側回転板１１′との間には、それぞれシャフト軸方向における隙間が形成されている。
【００２１】
図３の（１）〜（４）に示すように、その第１規制側回転板１１に複数の第１規制側開口４１が、シャフト周方向の等間隔をおいて並列するように形成されている。
その第２規制側回転板１１′に複数の第２規制側開口４１′が、シャフト周方向の等間隔をおいて並列するように形成されている。
その第１通過側回転板１２に、複数の第１通過側開口４２がシャフト周方向の等間隔をおいて並列するように形成されると共に、その第２規制側開口４１′と第１通過側回転板１２とのシャフト軸方向における重なり阻止用開口４３が、シャフト周方向の等間隔に並列するように複数形成され、シャフト周方向において第１通過側開口４２と重なり阻止用開口４３とは交互に並列する。
その第２通過側回転板１２′に、複数の第２通過側開口４２′がシャフト周方向の等間隔をおいて並列するように形成されると共に、その第１規制側開口４１と第２通過側回転板１２′とのシャフト軸方向における重なり阻止用開口４３′が、シャフト周方向の等間隔をおいて並列するように複数形成され、シャフト周方向において第２通過側開口４２′と重なり阻止用開口４３′とは交互に並列する。
各開口４１、４１′、４２、４２′、４３、４３′の数は、それぞれ本実施形態では４とされているが、その数は限定されず単一であってもよい。各開口４１、４１′、４２、４２′、４３、４３′は互いに形状と大きさが同一とされ、シャフト径方向に沿う一対の縁と、両シャフト３、４の軸心を中心とする円周に沿う一対の縁とを有する４辺形に沿う形状を有する。
【００２２】
シャフト径方向において、各コイル３３、３４の厚さ寸法Ｒ１は各開口４１、４１′、４２、４２′、４３、４３′の寸法Ｒ２未満とされると共に、各開口４１、４１′、４２、４２′、４３、４３′の内外周間に各コイル３３、３４の内外周が配置されている。また、シャフト径方向において、シャフト軸心から各コイルホルダー３１、３２内周端までの距離Ｒ３は、シャフト軸心から各開口４１、４１′、４２、４２′、４３、４３′の内周端までの距離Ｒ４未満とされ、シャフト軸心から各回転板１１、１１′、１２、１２′の外周端までの距離Ｒ５は、シャフト軸心から各コイルホルダー３１、３２の外周端までの距離Ｒ６未満とされている。これにより、シャフト３、４、回転板１１、１１′、１２、１２′、およびコイル３３、３４の径方向における相対位置が、製造公差や組み立て公差により変動しても、開口４１、４１′、４２、４２′、４３、４３′、と各通過側回転板１２、１２′をコイルの発生磁束の通過位置に配置できる。よって、各通過側回転板１２、１２′を通過する磁束の公差による変動をなくし、検出精度の低下を防止できる。
【００２３】
シャフト軸方向において、第１通過側開口４２と第１通過側回転板１２との重なり面積が両シャフト３、４の相対回転に応じて変化するように、その第１規制側開口４１と第１通過側開口４２とは両シャフト３、４の相対回転に応じて重なり面積が変化するように相対配置されている。また、シャフト軸方向において、第２規制側開口４１′と第２通過側回転板１２′との重なり面積が両シャフト３、４の相対回転に応じて変化するように、その第２規制側開口４１′と第２通過側開口４２′とは両シャフト３、４の相対回転に応じて重なり面積が変化するように相対配置されている。本実施形態では図４、５に示すように、両シャフト３、４が相対回転していない検出原点位置にある時、すなわち舵角が零の時、シャフト軸方向において第１規制側開口４１と第１通過側開口４２とは部分的に重なり、第１規制側開口４１のシャフト径方向に沿う一縁４１ａが第１通過側開口４２に重なり、第１通過側開口４２のシャフト径方向に沿う一縁４２ａが第１規制側開口４１に重なる。また、両シャフト３、４が相対回転していない検出原点位置にある時、シャフト軸方向において第２規制側開口４１′と第２通過側開口４２′とは部分的に重なり、第２規制側開口４１′のシャフト径方向に沿う一縁４１ａ′が第２通過側開口４２′に重なり、第２通過側開口４２′のシャフト径方向に沿う一縁４２ａ′が第２規制側開口４２′に重なる。
【００２４】
シャフト軸方向の一方側から見て、第１規制側開口４１に重なる第１通過側開口４２の一縁４２ａは、その第１通過側開口４２の中央に対してシャフト周方向の一方側に位置するのに対して、第２規制側開口４２′に重なる第２通過側開口４２′の一縁４２ａ′は、その第２通過側開口４２′の中央に対してシャフト周方向の他方側に位置するものとされている。また、両シャフト３、４が相対回転していない検出原点位置にある時、シャフト周方向において、第１通過側開口４２の一縁４２ａは第１規制側開口４１の中央位置に重なり、第２通過側開口４２′の一縁４２ａ′は第２規制側開口４２′の中央位置に重なる。これにより、その第１規制側開口４１と第１通過側回転板１２との重なり面積が、両シャフト３、４が一方向に相対回転する時は増加し他方向に相対回転する時は減少するように、その第１規制側開口４１と第１通過側開口４２とは相対配置され、また、その第２規制側開口４１′と第２通過側回転板１２′との重なり面積が、両シャフト３、４が一方向に相対回転する時は減少し他方向に相対回転する時は増加するように、その第２規制側開口４１′と第２通過側開口４２′とは相対配置されている。また、両シャフト３、４が相対回転していない検出原点位置にある時、その第１規制側開口４１と第１通過側回転板１２との重なり面積と、その第２規制側開口４１′と第２通過側回転板１２′との重なり面積とは互いに等しくされ、両シャフト３、４の相対回転時において、その第１規制側開口４１と第１通過側回転板１２との重なり面積の変化の絶対値と、その第２規制側開口４１′と第２通過側回転板１２′との重なり面積の変化の絶対値とは互いに等しくされている。
【００２５】
その第１規制側開口４１と、第２通過側回転板１２′の重なり阻止用開口４３′と、第１通過側回転板１２とは、その第１コイル３３の発生磁束の通過位置に配置される。その第２規制側開口４１′と、第１通過側回転板１２の重なり阻止用開口４３と、第２通過側回転板１２′は、その第２コイル３４の発生磁束の通過位置に配置される。図２において二点鎖線βで示すように、第１コイル３３の発生磁束が第１コイルホルダー３１、第１規制側開口４１、第２通過側回転板１２′の重なり阻止用開口４３′、第１通過側回転板１２を通過することで、その第１コイルホルダー３１および第１通過側回転板１２を構成要素として含む第１磁気回路が構成される。また、第２コイル３４の発生磁束が第２コイルホルダー３２、第２規制側開口４１′、第１通過側回転板１２の重なり阻止用開口４３、第２通過側回転板１２′を通過することで、その第２コイルホルダー３２および第２通過側回転板１２′を構成要素として含む第２磁気回路が構成される。
【００２６】
上記構成においては、トルク伝達時における両シャフト３、４の相対回転により、規制側回転板１１、１１′の規制側開口４１、４１′と通過側回転板１２、１２′の通過側開口４２、４２′との重なり状態が変化する。これにより、その規制側開口４１、４１′と通過側回転板１２、１２′との重なり面積が両シャフト３、４の相対回転に応じて変化する。その通過側回転板１２、１２′は磁性材製であり、その規制側回転板１１、１１′は非磁性材製であるので、その重なり面積の変化によって通過側回転板１２、１２′の通過磁束が変化する。また、そのコイルの磁束発生に基づき生じる交番磁界内で規制側回転板１１、１１′に生じる渦電流によっても、その通過側回転板１２、１２′に至る磁束が遮られる。これにより、その通過側回転板１２、１２′の通過磁束を、その重なり面積の変化に応じて変化させることができる。その面積変化は伝達トルクに対応する両シャフト３、４の相対回転に対応することから、その磁束変化に基づき両シャフト３、４により伝達されるトルクを検出できる。
【００２７】
上記構成によれば、コイル３３、３４を規制側回転板１１、１１′と通過側回転板１２、１２′と共にシャフト軸方向において並列するように配置できるので、径方向寸法を小さくできる。また、両シャフト３、４が一方向に相対回転した時と、他方向に相対回転した時の何れの場合にも、その相対回転量に応じたトルクを検出できる。また、各回転板１１、１１′、１２、１２′は円板状であり、各開口４１、４１′、４２、４２′、４３、４３′はシャフト周方向の間隔をおいて複数形成されているので、大型化することなく検出感度を向上することができる。
【００２８】
さらに上記構成によれば、その第１規制側開口４１と第１通過側回転板１２との重なり面積と、第２規制側開口４１′と第２通過側回転板１２′との重なり面積とは、両シャフト３、４が相対回転していない検出原点位置にある時は互いに等しく、両シャフト３、４の相対回転時は一方が増加すると共に他方が減少し、その変化の絶対値は互いに等しい。よって、その第１規制側開口４１と第１通過側回転板１２との重なり面積の変化に応じた第１通過側回転板１２の通過磁束変化と、第２規制側開口４１′と第２通過側回転板１２′との重なり面積の変化に応じた第２通過側回転板１２′の通過磁束変化との差に基づき、両シャフト３、４により伝達されるトルクを検出し、トルク検出感度を増大できる。しかも、温度が変動した場合、第１通過側回転板１２を通過する磁束と、第２通過側回転板１２′を通過する磁束とは同じだけ変化するので、両通過磁束変化の差に基づきトルクを検出することで温度変動による検出トルクの変動を相殺できる。よって、検出感度を向上すると同時に温度変化による検出値変動の補償ができ、構造の簡単化とコスト低減を図ることができる。
【００２９】
本実施形態では、各コイル３３、３４は、ハウジング２の外面側に取り付けられるプリント基板３５に配線を介して接続される。そのプリント基板３５に、図６に示すトルク検出回路が形成されている。その回路において、第１コイル３３は抵抗４５を介して発振器４６に接続され、第２コイル３４は抵抗４７を介して発振器４６に接続され、各コイル３３、３４は差動増幅回路４８に接続される。これにより、両シャフト３、４間でのトルク伝達によりトーションバー８が捩れることで両シャフト３、４が弾性的に相対回転し、その伝達トルクに応じて各規制側開口４１、４１′と通過側回転板１２、１２′との重なり面積が変化し、その重なり面積の変化により磁束通過部の通過磁束が変化することで、第１、第２コイル３３、３４の出力が変化する。その第１規制側開口４１と重なる第１通過側回転板１２の通過磁束の変化と、第２規制側開口４１′と重なる第２通過側回転板１２′の通過磁束の変化との差に対応する差動増幅回路４８の出力に基づき、両シャフト３、４により伝達されるトルクが検出される。その差動増幅回路４８から出力される伝達トルクに対応した信号に応じて駆動されるモータ等の図外アクチュエータにより操舵補助力が付与される。その操舵補助力の付与機構は公知の構成を採用できる。
【００３０】
図７〜図１１は本発明の第２実施形態のトルクセンサ１０１を示す。以下、上記第１実施形態との相違点を説明し、同様部分は同一符号で示す。図７、図８に示すように、そのトルクセンサ１０１は、第１実施形態における第１規制側開口４１と第１通過側回転板１２と同様の、第１シャフト３と同行回転する第１規制側回転板１１１と、第２シャフト４と同行回転する通過側回転板１１２は備えているが、第１実施形態の第２通過側回転板１２′に対応する第２通過側回転板を備えていない。また、本実施形態の第２規制側回転板１１１′は、第１シャフト３と同行回転可能、且つ、シャフト軸方向に直交する表裏面を有するものとされている。その第２規制側回転板１１１′は、第１規制側回転板１１１の外周端に連結部材１１０を介して連結されることで、第１シャフト３と同行回転する。その連結部材１１０は、本実施形態では第１規制側回転板１１１と一体とされている。
【００３１】
両規制側回転板１１１、１１１′と通過側回転板１１２と両コイル３３、３４とは、シャフト軸方向において並列するように配置され、両コイル３３、３４の間に両規制側回転板１１１、１１１′と通過側回転板１１２とが配置され、両規制側回転板１１１、１１１′の間に通過側回転板１１２が配置される。本実施形態では、第１コイルホルダー３１と第１規制側回転板１１１との間、第１規制側回転板１１１と通過側回転板１１２との間、通過側回転板１１２と第２規制側回転板１１１′との間、第２コイルホルダー３２と第２規制側回転板１１１′との間には、それぞれシャフト軸方向における隙間が形成されている。
【００３２】
図９の（１）〜（３）に示すように、第１規制側回転板１１１に第１規制側開口１４１が、第２規制側回転板１１１′に第２規制側開口１４１′が、第１実施形態の規制側開口４１、４１′と同様に形成されている。また、通過側回転板１１２に通過側開口１４２が第１実施形態の第１通過側開口４２と同様に形成されている。なお、重なり阻止用開口は形成されない。
【００３３】
シャフト軸方向において、その第１規制側開口１４１と通過側回転板１１２との重なり面積が両シャフト３、４の相対回転に応じて変化するように、その第１規制側開口１４１と通過側開口１４２とは両シャフト３、４の相対回転に応じて重なり面積が変化するように相対配置されている。また、シャフト軸方向において、その第２規制側開口１４１′と通過側回転板１１２との重なり面積が両シャフト３、４の相対回転に応じて変化するように、その第２規制側開口１４１′と通過側開口１４２とは両シャフト３、４の相対回転に応じて重なり面積が変化するように相対配置されている。本実施形態では図１０、１１に示すように、両シャフト３、４が相対回転していない検出原点位置にある時、すなわち舵角が零の時、シャフト軸方向において各規制側開口１４１、１４１′は通過側開口１４２と部分的に重なる。
【００３４】
また、両シャフト３、４が相対回転していない検出原点位置にある時、シャフト軸方向において、通過側開口１４２のシャフト径方向に沿う一方の縁１４２ａが第１規制側開口１４１におけるシャフト周方向中央位置に重なり、通過側開口１４２のシャフト径方向に沿う他方の縁１４２ｂが第２規制側開口１４１′におけるシャフト周方向中央位置に重なる。これにより、その第１規制側開口１４１と通過側回転板１１２との重なり面積が、両シャフト３、４が一方向に相対回転する時は増加し他方向に相対回転する時は減少するように、その第１規制側開口１４１と通過側開口１４２とは相対配置され、その第２規制側開口１４１′と通過側回転板１１２との重なり面積が、両シャフト３、４が一方向に相対回転する時は減少し他方向に相対回転する時は増加するように、その第２規制側開口１４１′と通過側開口１４２とは相対配置されている。また、両シャフト３、４が相対回転していない検出原点位置にある時、その第１規制側開口１４１と通過側回転板１１２との重なり面積と、その第２規制側開口１４１′と通過側回転板１１２との重なり面積とは互いに等しくされ、両シャフト３、４の相対回転時において、その第１規制側開口１４１と通過側回転板１１２との重なり面積の変化の絶対値と、その第２規制側開口１４１′と通過側回転板１１２との重なり面積の変化の絶対値とは互いに等しくされている。
【００３５】
その第１規制側開口１４１は第１コイル３３の発生磁束の通過位置に配置され、その第２規制側開口１４１′は第２コイル３４の発生磁束の通過位置に配置され、その通過側回転板１１２は両コイル３３、３４の発生磁束の通過位置に配置される。図８において二点鎖線βで示すように、第１コイル３３の発生磁束が第１コイルホルダー３１、第１規制側回転板１１１の第１規制側開口１４１、通過側回転板１１２を通過することで、その第１コイルホルダー３１および通過側回転板１１２を構成要素として含む第１磁気回路が構成される。また、第２コイル３４の発生磁束が第２コイルホルダー３２、第２規制側回転板１１１′の第２規制側開口１４１′、通過側回転板１１２を通過することで、その第２コイルホルダー３２および通過側回転板１２′を構成要素として含む第２磁気回路が構成される。
【００３６】
上記構成によれば、第１規制側開口１４１と通過側回転板１１２との重なり面積と、第２規制側開口１４１′と通過側回転板１１２との重なり面積とは、両シャフト３、４が相対回転していない検出原点位置にある時は互いに等しく、両シャフト３、４の相対回転時は一方が増加すると共に他方が減少し、その変化の絶対値は互いに等しい。よって、その第１規制側開口１４１と通過側回転板１１２との重なり面積の変化に応じた通過側回転板１１２の通過磁束変化と、第２規制側開口１４１′と通過側回転板１１２との重なり面積の変化に応じた通過側回転板１１２の通過磁束変化との差に基づき、第１実施形態と同様のトルク検出回路によって両シャフト３、４により伝達されるトルクを検出し、トルク検出感度を増大できる。しかも、温度が変動した場合、第１規制側開口１４１を介して通過側回転板１１２を通過する磁束と、第２規制側開口１４１′を介して通過側回転板１１２を通過する磁束とは同じだけ変化するので、両通過磁束変化の差に基づきトルクを検出することで温度変動による検出トルクの変動を相殺できる。よって、検出感度を向上すると同時に温度変化による検出値変動の補償ができ、構造の簡単化とコスト低減を図ることができる。
他は上記第１実施形態と同様の構成とされ、同様の作用効果を奏することができる。
【００３７】
本発明は上記実施形態に限定されない。例えば、各回転板に形成される開口は、上記各実施形態においては周囲が閉じた開口であるが、各回転板の外周側あるいは内周側において開放された開口であってもよい。また、第１シャフト３の一端側をステアリングギアに接続し、第２シャフト４の他端側をステアリングホイールに接続するようにしてもよい。また、第１実施形態における第２規制側回転板、第２通過側回転板、第２コイルをなくした構造、あるいは、第２実施形態における第２規制側回転板、第２コイルをなくした構造とし、第１規制側開口と第１通過側回転板との重なり面積の変化に応じた第１通過側回転板の通過磁束の変化のみに基づき、両シャフトにより伝達されるトルクを検出するようにしてもよい。さらに、本発明のトルクセンサをステアリング装置以外においてトルクを検出するために用いてもよい。
【００３８】
【発明の効果】
本発明によれば、小型化、感度向上、精度向上、構造の簡単化、コスト低減を図ることができるトルクセンサを提供できる。
【図面の簡単な説明】
【図１】本発明の第１実施形態のトルクセンサの断面図
【図２】本発明の第１実施形態のトルクセンサの要部の断面図
【図３】本発明の第１実施形態のトルクセンサの（１）は第１規制側回転板の正面図、（２）は第２通過側回転板の正面図、（３）は第１通過側回転板の正面図、（４）は第２規制側回転板の正面図
【図４】（１）は図２のＩＶａ−ＩＶａ線断面図、（２）は図２のＩＶｂ−ＩＶｂ線断面図
【図５】図４（１）のＶ−Ｖ線断面図
【図６】本発明の実施形態のトルク検出回路を示す図
【図７】本発明の第２実施形態のトルクセンサの断面図
【図８】本発明の第２実施形態のトルクセンサの要部の断面図
【図９】本発明の第２実施形態のトルクセンサの（１）は第１規制側回転板の正面図、（２）は通過側回転板の正面図、（３）は第２規制側回転板の正面図
【図１０】（１）は図８のＸａ−Ｘａ線断面図、（２）は図８のＸｂ−Ｘｂ線断面図
【図１１】図１０（１）のＸＩ−ＸＩ線断面図
【符号の説明】
１トルクセンサ
３第１シャフト
４第２シャフト
１１、１１１第１規制側回転板
１１′、１１１′ 第２規制側回転板
１２第１通過側回転板
１１２通過側回転板
１２′ 第２通過側回転板
３１第１コイルホルダー
３２第２コイルホルダー
３３第１コイル
３４第２コイル
４１、１４１第１規制側開口
４１′、１４１′ 第２規制側開口
４２第１通過側開口
１４２通過側開口
４２′ 第２通過側開口
４３、４３′ 重なり阻止用開口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a torque sensor suitable for detecting the steering torque in, for example, a power steering apparatus that applies a steering assist force according to the steering torque.
[0002]
[Prior art]
For example, in a power steering device for a vehicle, when the rotation of a steering wheel is transmitted to a wheel via a steering shaft, torque transmitted by the steering shaft is detected by a torque sensor, and steering is performed according to the magnitude of the detected torque. Auxiliary power is given.
[0003]
As such a torque sensor, a sensor that detects torque based on a change in magnetic resistance in accordance with a torque change has been conventionally used. A torque sensor based on the detection principle includes a first shaft, a second shaft elastically coupled to the first shaft so as to be relatively rotatable, and a first detection ring made of a magnetic material fixed to the first shaft. And a second detection ring made of a magnetic material fixed to the second shaft, and a coil that covers between the two detection rings. A plurality of teeth are provided on the end face of each detection ring along the circumferential direction, and the teeth of one detection ring and the teeth of the other detection ring face each other via an air gap. In this torque sensor, when the two detection rings rotate relative to each other due to torque transmission by both shafts, the facing area between the teeth of one detection ring and the teeth of the other detection ring changes. Due to the change in area, the magnetic resistance to the magnetic flux generated by the coil passing through the air gap between the teeth of both detection rings changes. Based on the change in the magnetic resistance, the torque transmitted by both shafts is detected. Furthermore, in order to compensate for fluctuations in the detected torque value due to temperature changes, a magnetic flux generating coil having the same specifications as the above coils and a magnetic circuit for detecting changes due to temperature changes in the magnetic resistance with respect to the magnetic flux are provided. .
[0004]
[Problems to be solved by the invention]
In the conventional torque sensor, since the outer sides of the first and second detection rings projecting radially from both shafts are covered with the coil, the radial dimension is increased. In addition, a decrease in detection accuracy due to accumulation of assembly errors and processing errors becomes a problem. Further, in order to increase the detection sensitivity, it is necessary to increase the number of teeth provided in each detection ring. However, if this is done, the projecting dimension of each detection ring from each shaft is increased and the size is further increased. Furthermore, a dedicated magnetic circuit is required only for compensating for the detected value variation due to temperature change, the shaft axial dimension increases, the structure becomes complicated, and the manufacturing cost increases.
[0005]
An object of this invention is to provide the torque sensor which can solve the said problem.
[0006]
[Means for Solving the Problems]
The torque sensor of the present invention includes a first shaft, a second shaft that is coaxially and elastically coupled to the first shaft, and capable of rotating relative to the first shaft. A regulation-side rotating plate made of a conductive non-magnetic material having orthogonal front and back surfaces, a passing-side rotating plate made of magnetic material that can be rotated along with the second shaft and has front and back surfaces orthogonal to the shaft axial direction, And a coil that generates magnetic flux so as to generate an alternating magnetic field, and the regulation-side rotating plate, the passing-side rotating plate, and the coil are arranged in parallel in the shaft axial direction. The regulating-side rotating plate is arranged between the passing-side rotating plate and the coil, and the regulating-side rotating plate and the passing-side rotating plate are arranged at a passage position of the generated magnetic flux of the coil. A restriction-side opening is formed in the restriction-side rotation plate, a passage-side opening is formed in the passage-side rotation plate, and the overlapping area of the restriction-side opening and the passage-side rotation plate is the relative rotation of both shafts in the shaft axial direction. The restricting side opening and the passing side opening are relatively arranged so that the overlapping area changes according to the relative rotation of both shafts, and the passing side rotating plate according to the change of the overlapping area is changed. Based on the change in the passing magnetic flux, the torque transmitted by both shafts is detected.
As the magnetic material constituting the passing side rotating plate, for example, a soft magnetic metal material or a magnetic resin material having excellent magnetic characteristics necessary for constituting the torque sensor can be used. As the non-magnetic material having conductivity which constitutes the regulating-side rotating plate, a paramagnetic material having excellent conductivity and low permeability such as aluminum can be used.
In the above configuration, the overlapping state of the restriction side opening of the restriction side rotating plate and the passing side opening of the passing side rotating plate changes due to the relative rotation of both shafts during torque transmission. Thereby, the overlapping area of the restriction side opening and the passing side rotation plate changes according to the relative rotation of both shafts. Since the passing-side rotating plate is made of a magnetic material and the regulating-side rotating plate is made of a non-magnetic material, the passing magnetic flux of the passing-side rotating plate changes depending on the change in the overlapping area. Further, the magnetic flux reaching the passing side rotating plate is also blocked by the eddy current generated in the regulating side rotating plate in the alternating magnetic field generated based on the generation of magnetic flux of the coil. Thereby, the passage magnetic flux of the passage side rotating plate can be changed according to the change of the overlapping area. Since the change in area corresponds to the relative rotation of both shafts corresponding to the transmission torque, the torque transmitted by both shafts can be detected based on the change in magnetic flux.
According to the said structure, since a coil can be arrange | positioned so that it may parallel in a shaft axial direction with a regulation side rotating plate and a passage side rotating plate, a radial direction dimension can be made small.
[0007]
The torque sensor of the present invention includes a first shaft, a second shaft that is coaxially and elastically coupled to the first shaft, and capable of rotating relative to the first shaft. A first regulation-side rotating plate made of a conductive nonmagnetic material having front and back surfaces orthogonal to each other, and a first passage side made of magnetic material that can rotate with the second shaft and have front and back surfaces orthogonal to the shaft axial direction. A rotating plate, a second passing-side rotating plate made of a magnetic material having front and back surfaces orthogonal to the shaft axis direction, which can rotate with the first shaft, and a shaft shaft which can rotate with the second shaft. The first and second coils having the same specification, each of which is composed of a second regulating side rotating plate having front and back surfaces orthogonal to the direction and a conductive wire wound around the shaft axis and generates magnetic flux so as to generate an alternating magnetic field When Both regulation side rotating plate, both passing side rotating plate and both coils are arranged in parallel in the shaft axial direction, and both regulating side rotating plate and both passing side rotating plate are arranged between both coils. The both passing side rotating plates are arranged between the both regulating side rotating plates, the first regulating side rotating plate and the second passing side rotating plate are arranged between the first coil and the first passing side rotating plate, and the first A second regulating side rotating plate and a first passing side rotating plate are arranged between the two coils and the second passing side rotating plate, a first regulating side opening is formed in the first regulating side rotating plate, and the second A second restricting-side opening is formed in the restricting-side rotating plate, the first passing-side rotating plate has an overlap in the shaft axis direction between the first passing-side opening and the second restricting-side opening and the first passing-side rotating plate. A blocking opening is formed, and the second passage side rotating plate has a second passage side opening and the first restriction side opening. An opening for preventing overlap in the shaft axial direction with the second passage side rotating plate is formed, and the first restriction side opening, the opening for preventing overlap of the second passage side rotating plate, and the first passage side rotating plate are: The first coil is disposed at a position where the magnetic flux generated by the first coil passes, and the second restricting side opening, the overlap preventing opening of the first passing side rotating plate, and the second passing side rotating plate are generated by the second coil. Arranged at the magnetic flux passage position, in the shaft axis direction, the overlapping area of the first restriction side opening and the first passage side rotating plate increases when both shafts rotate in one direction and rotates in the other direction. The first restricting side opening and the first passing side opening are relatively arranged so as to decrease, and in the shaft axial direction, the overlapping area of the second restricting side opening and the second passing side rotating plate is, When both shafts rotate relative to one direction, it decreases and the other direction The second restriction-side opening and the second passage-side opening are relatively arranged so as to increase when they rotate relative to each other, and when the shafts are at the detection origin position where they are not relatively rotating, the first restriction-side opening and The overlapping area of the first passing side rotating plate and the overlapping area of the second restricting side opening and the second passing side rotating plate are equal to each other. The absolute value of the change in the overlapping area with the first passing side rotating plate and the absolute value of the change in the overlapping area between the second regulating side opening and the second passing side rotating plate are equal to each other, and the first regulating side Changes in the passing magnetic flux of the first passing side rotating plate according to changes in the overlapping area of the opening and the first passing side rotating plate, and changes in the overlapping area of the second regulating side opening and the second passing side rotating plate Based on the difference from the change in the passing magnetic flux of the corresponding second passing side rotating plate, Preferably, the torque transmitted by preparative is detected.
According to this configuration, the overlapping area of the first restriction side opening and the first passing side rotating plate and the overlapping area of the second restricting side opening and the second passing side rotating plate are such that both shafts rotate relative to each other. When the two shafts are at the detected origin position, they are equal to each other. When the shafts rotate relative to each other, one increases and the other decreases, and the absolute values of the changes are equal to each other. Therefore, the change of the passing magnetic flux of the first passing side rotating plate according to the change of the overlapping area of the first restricting side opening and the first passing side rotating plate, and the second restricting side opening and the second passing side rotating plate Torque transmitted by both shafts can be detected based on the difference from the passage magnetic flux change of the second passage side rotating plate in accordance with the change of the overlapping area, and the torque detection sensitivity can be increased. In addition, when the temperature fluctuates, the magnetic flux that passes through the first passing side rotating plate and the magnetic flux that passes through the second passing side rotating plate change by the same amount, so that the torque is detected based on the difference between both passing magnetic flux changes. Thus, fluctuations in detected torque due to temperature fluctuations can be offset. Therefore, it is possible to improve the detection sensitivity and at the same time compensate for the detection value variation due to the temperature change, thereby simplifying the structure and reducing the cost.
[0008]
The torque sensor of the present invention includes a shaft, a second shaft that is coaxially and elastically connected to the first shaft, and capable of rotating together with the first shaft, and is orthogonal to the shaft axis direction. A first regulating side rotating plate made of a conductive nonmagnetic material having front and back surfaces, a second regulating side rotating plate having front and back surfaces that can be rotated along with the first shaft and orthogonal to the shaft axial direction, and Consisting of a passage-side rotating plate made of a magnetic material having front and back surfaces orthogonal to the shaft axis direction, which can be rotated along with the second shaft, and a conductive wire wound around the shaft axis so as to generate an alternating magnetic field The first and second coils having the same specifications that generate magnetic flux are provided, and both the regulation-side rotating plate, the passage-side rotating plate, and both coils are arranged in parallel in the shaft axial direction, and between the two coils. A regulating side rotating plate and a passing side rotating plate are arranged, a passing side rotating plate is arranged between both regulating side rotating plates, a first regulating side opening is formed in the first regulating side rotating plate, and the second regulating side A second regulating side opening is formed in the rotating plate, a passing side opening is formed in the passing side rotating plate, the first regulating side opening is disposed at a passage position of the generated magnetic flux of the first coil, and the second The restriction-side opening is disposed at the passage position of the magnetic flux generated by the second coil, the passage-side rotation plate is disposed at the passage position of the magnetic flux generated by both coils, and the second restriction-side opening and the passage-side rotation plate are The overlapping area of the first regulating side opening and the passing side rotating plate in the shaft axial direction increases when the shafts rotate relative to each other in the shaft axial direction. When the relative rotation in the other direction, the first regulation is reduced. The side opening and the passage side opening are arranged relative to each other, and in the shaft axial direction, the overlapping area of the second restriction side opening and the passage side rotating plate decreases when both shafts rotate in one direction and decreases in the other direction. The second restriction side opening and the passage side opening are relatively arranged so as to increase when they rotate relative to each other, and when both shafts are at the detection origin position where they are not relatively rotated, the first restriction side opening and the passage side The overlapping area of the rotating plate and the overlapping area of the second regulating side opening and the passing side rotating plate are equal to each other, and when the two shafts are relatively rotated, the first regulating side opening and the passing side rotating plate The absolute value of the change in the overlap area and the absolute value of the change in the overlap area between the second restriction side opening and the passage side rotating plate are equal to each other, and the overlap area between the first restriction side opening and the passage side rotation plate is the same. Passing side rotating plate passing according to the change of The torque transmitted by both shafts is detected based on the difference between the change in magnetic flux and the change in the passing magnetic flux of the passing side rotating plate in accordance with the change in the overlapping area between the second regulating side opening and the passing side rotating plate. It is preferable.
According to this configuration, the overlapping area between the first restriction side opening and the passing side rotating plate and the overlapping area between the second restriction side opening and the passing side rotating plate are the detection origin where the two shafts are not rotating relative to each other. When in position, they are equal to each other, and when the shafts rotate relative to each other, one increases and the other decreases, and the absolute values of the changes are equal to each other. Therefore, according to the change of the passing magnetic flux of the passing side rotating plate according to the change of the overlapping area of the first restricting side opening and the passing side rotating plate, and according to the change of the overlapping area of the second restricting side opening and the passing side rotating plate. The torque transmitted by both shafts can be detected based on the difference from the passing magnetic flux change of the passing side rotating plate, and the torque detection sensitivity can be increased. In addition, when the temperature fluctuates, the magnetic flux passing through the passing-side rotating plate via the first restricting-side opening and the magnetic flux passing through the passing-side rotating plate via the second restricting-side opening change by the same amount. By detecting the torque based on the difference between the two passing magnetic flux changes, it is possible to cancel the detected torque fluctuation due to temperature fluctuation. Therefore, it is possible to improve the detection sensitivity and at the same time compensate for the detection value variation due to the temperature change, thereby simplifying the structure and reducing the cost.
[0009]
In the shaft radial direction, it is preferable that the thickness dimension of the coil is less than the dimension of each opening, and the inner and outer circumferences of the coil are arranged between the inner and outer circumferences of each opening. Thereby, even if the relative position in the radial direction of the shaft, the rotating plate, and the coil fluctuates due to manufacturing tolerances and assembly tolerances, the opening can be arranged at the passage position of the magnetic flux generated by the coils. Therefore, the fluctuation due to the tolerance of the passing magnetic flux of the passing side rotating plate can be eliminated, and the deterioration of the detection accuracy can be prevented.
And a coil holder made of a magnetic material for holding the coil. The coil holder includes a cylindrical outer peripheral portion surrounding the outer peripheral side of the coil, and a cylindrical inner peripheral portion surrounding the inner peripheral side of the coil. The outer peripheral portion and a portion connecting one end portion on the side away from the rotating plate in the inner peripheral portion, and in the shaft radial direction, the distance from the shaft axis to the inner peripheral end of the coil holder is the shaft axis In the shaft radial direction, the distance from the shaft axis to the outer peripheral edge of each rotary plate is less than the distance from the shaft axis to the outer peripheral edge of the coil holder in the shaft radial direction. It is preferable.
Thereby, an opening and a passage side rotation board can be certainly arranged in a passage position of magnetic flux generated by a coil. The fluctuation due to the tolerance of the passing magnetic flux of the passing side rotating plate can be eliminated.
[0010]
Each opening preferably has a shape along a quadrilateral having a pair of edges along the radial direction of the shaft and a pair of edges along the circumference centered on the axis of both shafts.
As a result, it is possible to detect a torque corresponding to the amount of relative rotation in both cases where both shafts are relatively rotated in one direction and when they are relatively rotated in the other direction.
[0011]
Each rotating plate is preferably formed in a disk shape coaxial with both shafts, and a plurality of openings are preferably formed in parallel with each rotating plate at intervals in the shaft circumferential direction. Thereby, torque detection sensitivity can be improved without increasing the size.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A torque sensor 1 according to the first embodiment shown in FIGS. 1 to 6 detects a steering torque in a power steering device of a vehicle. The torque sensor 1 includes a housing 2, a first shaft 3, and a second shaft 4. The first shaft 3 is supported by the housing 2 via a bearing 5 and is supported by an inner periphery of a recess 4 a formed at one end of the second shaft 4 via a bush 6. The second shaft 4 is supported by the housing 2 via a bearing 7. Steering according to the detected torque auxiliary Power is granted.
[0013]
A torsion bar 8 is inserted into the axial hole 3 a formed in the first shaft 3 and the recess 4 a of the second shaft 4. One end of the torsion bar 8 is connected to the first shaft 3 by a pin 9 so as to rotate together, and the other end is connected to the second shaft 4 via a serration 10 so as to rotate together. Thus, the second shaft 4 is arranged coaxially with the first shaft 3 and is elastically coupled to the first shaft 3 so as to be relatively rotatable. One end side of the first shaft 3 is connected to a steering wheel (not shown), and the other end side of the second shaft 4 is connected to a steering gear such as a rack and pinion type steering gear. Thereby, the rotation of the steering wheel for steering is transmitted to the wheels via the first and second shafts 3 and 4, and the steering angle changes.
[0014]
The first shaft 3 is connected to a disc-shaped first regulating-side rotating plate 11 having front and back surfaces orthogonal to the shaft axis direction so as to rotate coaxially. In the present embodiment, the first regulating-side rotating plate 11 is formed integrally with the cylinder 13, and the cylinder 13 is press-fitted into the outer periphery of the first shaft 3 via a cylinder 14 ′ described later. Although it rotates accompanying the 1st shaft 3, the connection means of the 1st control side rotating plate 11 and the 1st shaft 3 is not specifically limited. This 1st control side rotating plate 11 is made from the nonmagnetic material which has electroconductivity, such as aluminum.
[0015]
The second shaft 4 is connected to a disc-shaped first passage-side rotating plate 12 having front and back surfaces orthogonal to the shaft axis direction so as to rotate coaxially. In the present embodiment, the first passage-side rotating plate 12 is formed integrally with the cylinder 14, and the cylinder 14 rotates together with the second shaft 4 by being press-fitted into the outer periphery of the second shaft 4. The connecting means between the first passing side rotary plate 12 and the second shaft 4 is not particularly limited. The first passage-side rotating plate 12 is made of a magnetic material such as a soft magnetic metal material.
[0016]
The first shaft 3 is connected to a disc-shaped second passing side rotating plate 12 ′ having front and back surfaces orthogonal to the shaft axial direction so as to rotate coaxially. In the present embodiment, the second passage-side rotating plate 12 ′ is formed integrally with the cylinder 14 ′, and the cylinder 14 ′ is press-fitted into the outer periphery of the first shaft 3 to accompany the first shaft 3. Although it rotates, the connection means of the 2nd passage side rotating plate 12 'and the 1st shaft 3 is not specifically limited. The second passage-side rotating plate 12 'is made of a magnetic material such as a soft magnetic metal material.
[0017]
The second shaft 4 is connected to a disc-shaped second regulating side rotating plate 11 ′ having front and back surfaces orthogonal to the shaft axial direction so as to rotate coaxially. In the present embodiment, the second regulating-side rotating plate 11 ′ is formed integrally with the cylinder 13 ′, and the cylinder 13 ′ is press-fitted into the outer periphery of the second shaft 4 via the cylinder 14. However, the connecting means for connecting the second regulating side rotating plate 11 ′ and the second shaft 4 is not particularly limited. The second regulating-side rotating plate 11 ′ is made of a nonmagnetic material having conductivity such as aluminum. The rotary plates 11, 11 ', 12, 12' have the same shape and size.
[0018]
A first coil holder 31 made of a magnetic material and a second coil holder 32 made of a magnetic material are inserted into the inner periphery of the housing 2. As shown in FIG. 2, each of the coil holders 31 and 32 includes cylindrical outer peripheral portions 31a and 32a, cylindrical inner peripheral portions 31b and 32b, outer peripheral portions 31a and 32a, and inner peripheral portions 31b and 32b. It is comprised from the annular parts 31c and 32c which connect one end part. Each coil holder 31, 32 is sandwiched between a leaf spring 54 and a spacer 55 by a step 2 a formed on the inner periphery of the housing 2 and a retaining ring 53 fitted on the inner periphery of the housing 2. To be fixed to the housing 2. The coil holders 31 and 32 are arranged so as to surround the outer periphery of the shafts 3 and 4 with a gap.
[0019]
The first coil 33 is held by the first coil holder 31, and the second coil 34 is held by the second coil holder 32. That is, the coil holders 31 and 32 surround the outer peripheral sides of the coils 33 and 34 with the outer peripheral portions 31a and 32a, and the inner peripheral sides of the coils 33 and 34 with the inner peripheral portions 31b and 32b. Both coils 33 and 34 have the same specifications, and are constituted by conducting wires 33a and 34a wound around shaft shafts around bobbins 36 and 37 made of an insulating material to constitute a torque detection circuit as will be described later and generate an alternating magnetic field. So as to generate magnetic flux.
[0020]
Both regulating side rotating plates 11, 11 ', both passing side rotating plates 12, 12', and both coils 33, 34 are arranged in parallel in the shaft axial direction. Both regulating side rotating plates 11, 11 ′ and both passing side rotating plates 12, 12 ′ are arranged between both coils 33, 34, and both passing side rotations are arranged between both regulating side rotating plates 11, 11 ′. Plates 12 and 12 'are arranged. Between the first coil 33 and the first passing side rotating plate 12, the first regulating side rotating plate 11 and the second passing side rotating plate 12' are arranged, and the second coil. The second restricting-side rotating plate 11 ′ and the first passing-side rotating plate 12 are disposed between 34 and the second passing-side rotating plate 12 ′. The annular portions 31c and 32c of the coil holders 31 and 32 connect one end of the outer peripheral portions 31a and 32a and the inner peripheral portions 31b and 32b on the side away from the rotary plates 11 and 12, respectively. In the present embodiment, between the first coil holder 31 and the first regulating side rotating plate 11, between the first passing side rotating plate 12 and the second passing side rotating plate 12 ′, and between the second coil holder 32 and the second rotating plate 12 ′. A gap in the shaft axial direction is formed between each of the two regulating-side rotating plates 11 ′.
[0021]
As shown in (1) to (4) of FIG. 3, a plurality of first restriction side openings 41 are formed in the first restriction side rotating plate 11 so as to be arranged in parallel at equal intervals in the shaft circumferential direction. Yes.
A plurality of second restriction side openings 41 ′ are formed in the second restriction side rotating plate 11 ′ so as to be arranged in parallel at equal intervals in the circumferential direction of the shaft.
A plurality of first passage side openings 42 are formed in the first passage side rotating plate 12 so as to be arranged in parallel at equal intervals in the circumferential direction of the shaft, and the second restriction side opening 41 ′ and the first passage side A plurality of overlap prevention openings 43 in the shaft axial direction with the rotary plate 12 are formed so as to be arranged at equal intervals in the shaft circumferential direction, and the first passage side openings 42 and the overlap prevention openings 43 are alternately arranged in the shaft circumferential direction. Parallel to
A plurality of second passage-side openings 42 ′ are formed in the second passage-side rotating plate 12 ′ so as to be arranged at equal intervals in the circumferential direction of the shaft, and the first restriction-side opening 41 and the second passage are arranged. A plurality of openings 43 ′ for preventing overlap with the side rotating plate 12 ′ in the shaft axial direction are formed so as to be arranged in parallel at equal intervals in the circumferential direction of the shaft, and overlapping with the second passage side opening 42 ′ in the circumferential direction of the shaft. The openings 43 'are alternately arranged in parallel.
The number of each opening 41, 41 ', 42, 42', 43, 43 'is 4 in this embodiment, but the number is not limited and may be single. Each of the openings 41, 41 ', 42, 42', 43, 43 'has the same shape and size as each other, a pair of edges along the shaft radial direction, and a circle centering on the shaft center of both shafts 3, 4. It has a shape along a quadrilateral having a pair of edges along the circumference.
[0022]
In the shaft radial direction, the thickness dimension R1 of each coil 33, 34 is less than the dimension R2 of each opening 41, 41 ', 42, 42', 43, 43 ', and each opening 41, 41', 42, The inner and outer peripheries of the coils 33 and 34 are arranged between the inner and outer peripheries of 42 ', 43 and 43'. In the shaft radial direction, the distance R3 from the shaft axis to the inner peripheral ends of the coil holders 31 and 32 is the inner peripheral ends of the openings 41, 41 ', 42, 42', 43, and 43 'from the shaft axis. The distance R5 from the shaft axis to the outer peripheral edge of each rotary plate 11, 11 ', 12, 12' is the distance R6 from the shaft axis to the outer peripheral edge of each coil holder 31, 32. It is said that it is less than. Thereby, even if the relative positions in the radial direction of the shafts 3 and 4, the rotating plates 11, 11 ′, 12 and 12 ′ and the coils 33 and 34 vary due to manufacturing tolerances and assembly tolerances, the openings 41, 41 ′, 42, 42 ′, 43, 43 ′ and the respective passing side rotating plates 12, 12 ′ can be arranged at positions where the magnetic flux generated by the coil passes. Therefore, the fluctuation due to the tolerance of the magnetic flux passing through each of the passing-side rotating plates 12 and 12 ′ can be eliminated, and the detection accuracy can be prevented from being lowered.
[0023]
In the shaft axial direction, the first restriction side opening 41 and the first passage 41 are arranged so that the overlapping area of the first passage side opening 42 and the first passage side rotating plate 12 changes according to the relative rotation of the shafts 3 and 4. The passage-side opening 42 is disposed so that the overlapping area changes according to the relative rotation of the shafts 3 and 4. Further, in the shaft axial direction, the second restriction side opening is arranged such that the overlapping area of the second restriction side opening 41 ′ and the second passage side rotation plate 12 ′ changes according to the relative rotation of the shafts 3 and 4. 41 'and 2nd passage side opening 42' are relatively arranged so that an overlapping area may change according to relative rotation of both shafts 3 and 4. As shown in FIG. In the present embodiment, as shown in FIGS. 4 and 5, when the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, that is, when the steering angle is zero, The first passage side opening 42 partially overlaps, and one edge 41a along the shaft radial direction of the first restriction side opening 41 overlaps the first passage side opening 42, and extends along the shaft radial direction of the first passage side opening 42. One edge 42 a overlaps the first restriction side opening 41. When the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, the second restriction side opening 41 ′ and the second passage side opening 42 ′ partially overlap in the shaft axial direction, and the second restriction side One edge 41a 'along the shaft radial direction of the opening 41' overlaps with the second passage side opening 42 ', and one edge 42a' along the shaft radial direction of the second passage side opening 42 'with the second restriction side opening 42'. Overlap.
[0024]
When viewed from one side in the shaft axis direction, one edge 42a of the first passage side opening 42 that overlaps the first restriction side opening 41 is located on one side in the shaft circumferential direction with respect to the center of the first passage side opening 42. On the other hand, one edge 42a 'of the second passage side opening 42' overlapping the second restriction side opening 42 'is positioned on the other side in the circumferential direction of the shaft with respect to the center of the second passage side opening 42'. It is supposed to be. When the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, the edge 42a of the first passage side opening 42 overlaps the center position of the first restriction side opening 41 in the shaft circumferential direction, and the second One edge 42a 'of the passage side opening 42' overlaps with the center position of the second restriction side opening 42 '. As a result, the overlapping area between the first restriction side opening 41 and the first passage side rotating plate 12 increases when both shafts 3 and 4 rotate in one direction and decreases when they rotate in the other direction. As described above, the first restricting side opening 41 and the first passing side opening 42 are relatively disposed, and the overlapping area between the second restricting side opening 41 'and the second passing side rotating plate 12' is such that both shafts The second restricting side opening 41 'and the second passing side opening 42' are relatively arranged so that they decrease when 3, 4 rotates relative to one direction and increase when they rotate relative to the other direction. . Further, when the shafts 3 and 4 are at the detection origin position where they are not relatively rotated, the overlapping area of the first restriction side opening 41 and the first passage side rotation plate 12 and the second restriction side opening 41 ' The overlapping area with the second passing side rotating plate 12 ′ is equal to each other, and the change in the overlapping area between the first regulating side opening 41 and the first passing side rotating plate 12 when the shafts 3 and 4 are rotated relative to each other. And the absolute value of the change in the overlapping area between the second restricting-side opening 41 ′ and the second passage-side rotating plate 12 ′ are equal to each other.
[0025]
The first restricting side opening 41, the overlap preventing opening 43 'of the second passing side rotating plate 12', and the first passing side rotating plate 12 are arranged at a passage position of the magnetic flux generated by the first coil 33. The The second restricting side opening 41 ′, the overlap preventing opening 43 of the first passing side rotating plate 12, and the second passing side rotating plate 12 ′ are arranged at a passage position of the magnetic flux generated by the second coil 34. . As indicated by a two-dot chain line β in FIG. 2, the magnetic flux generated by the first coil 33 causes the first coil holder 31, the first restricting side opening 41, the overlap preventing opening 43 ′ of the second passing side rotating plate 12 ′, A first magnetic circuit including the first coil holder 31 and the first passing side rotating plate 12 as components is configured by passing through the one passing side rotating plate 12. Further, the magnetic flux generated by the second coil 34 passes through the second coil holder 32, the second restriction side opening 41 ', the overlap prevention opening 43 of the first passing side rotating plate 12, and the second passing side rotating plate 12'. Thus, a second magnetic circuit including the second coil holder 32 and the second passage-side rotating plate 12 ′ as components is configured.
[0026]
In the above configuration, due to the relative rotation of the shafts 3 and 4 during torque transmission, the restriction-side openings 41 and 41 'of the restriction-side rotation plates 11 and 11' and the passage-side openings 42 and 12 'of the passage-side rotation plates 12 and 12' The overlapping state with 42 'changes. Thereby, the overlapping area of the restriction side openings 41 and 41 ′ and the passing side rotation plates 12 and 12 ′ changes according to the relative rotation of the shafts 3 and 4. Since the passing side rotating plates 12 and 12 'are made of a magnetic material and the regulating side rotating plates 11 and 11' are made of a non-magnetic material, the passage of the passing side rotating plates 12 and 12 'passes due to the change in the overlapping area. Magnetic flux changes. Further, the magnetic flux reaching the passing-side rotating plates 12 and 12 ′ is also blocked by the eddy current generated in the regulating-side rotating plates 11 and 11 ′ in the alternating magnetic field generated based on the generation of the magnetic flux of the coil. Thereby, the passage magnetic flux of the passage side rotating plates 12 and 12 'can be changed according to the change of the overlapping area. Since the change in area corresponds to the relative rotation of both shafts 3 and 4 corresponding to the transmission torque, the torque transmitted by both shafts 3 and 4 can be detected based on the change in magnetic flux.
[0027]
According to the above configuration, the coils 33 and 34 can be arranged in parallel with the regulating side rotating plates 11 and 11 'and the passing side rotating plates 12 and 12' in the shaft axial direction, so that the radial dimension can be reduced. Also, the torque corresponding to the amount of relative rotation can be detected both when the shafts 3 and 4 are relatively rotated in one direction and when they are relatively rotated in the other direction. Each of the rotating plates 11, 11 ', 12, 12' has a disk shape, and a plurality of openings 41, 41 ', 42, 42', 43, 43 'are formed at intervals in the shaft circumferential direction. Therefore, the detection sensitivity can be improved without increasing the size.
[0028]
Further, according to the above configuration, the overlapping area of the first restriction side opening 41 and the first passing side rotating plate 12 and the overlapping area of the second restricting side opening 41 ′ and the second passing side rotating plate 12 ′ are: When the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, they are equal to each other. When the shafts 3 and 4 are rotated relative to each other, one increases and the other decreases, and the absolute values of the changes are equal to each other. . Therefore, the change in the passing magnetic flux of the first passing side rotating plate 12 according to the change in the overlapping area of the first restricting side opening 41 and the first passing side rotating plate 12, and the second restricting side opening 41 ′ and the second passing state. The torque transmitted by both shafts 3 and 4 is detected based on the difference from the passing magnetic flux change of the second passing side rotating plate 12 'according to the change of the overlapping area with the side rotating plate 12', and the torque detection sensitivity is increased. Can increase. In addition, when the temperature fluctuates, the magnetic flux passing through the first passing-side rotating plate 12 and the magnetic flux passing through the second passing-side rotating plate 12 ′ change by the same amount. By detecting this, fluctuations in detected torque due to temperature fluctuations can be offset. Therefore, it is possible to improve the detection sensitivity and at the same time compensate for the detection value variation due to the temperature change, thereby simplifying the structure and reducing the cost.
[0029]
In the present embodiment, the coils 33 and 34 are connected to a printed circuit board 35 attached to the outer surface side of the housing 2 via wiring. A torque detection circuit shown in FIG. 6 is formed on the printed board 35. In the circuit, the first coil 33 is connected to the oscillator 46 through the resistor 45, the second coil 34 is connected to the oscillator 46 through the resistor 47, and the coils 33 and 34 are connected to the differential amplifier circuit 48. The As a result, the torsion bar 8 is twisted by torque transmission between the shafts 3 and 4 so that the shafts 3 and 4 are elastically rotated relative to each other. The overlapping area with the passage-side rotating plates 12 and 12 'changes, and the output of the first and second coils 33 and 34 changes as the passing magnetic flux of the magnetic flux passing part changes due to the change of the overlapping area. Corresponding to the difference between the change in the passage magnetic flux of the first passage-side rotating plate 12 that overlaps the first restriction-side opening 41 and the change in the passage magnetic flux of the second passage-side rotation plate 12 'that overlaps the second restriction-side opening 41'. Based on the output of the differential amplifier circuit 48, the torque transmitted by both shafts 3 and 4 is detected. A steering assist force is applied by an unillustrated actuator such as a motor driven in accordance with a signal corresponding to the transmission torque output from the differential amplifier circuit 48. A known configuration can be adopted as the steering assist force applying mechanism.
[0030]
7 to 11 show a torque sensor 101 according to a second embodiment of the present invention. Hereinafter, differences from the first embodiment will be described, and similar parts are denoted by the same reference numerals. As shown in FIGS. 7 and 8, the torque sensor 101 is the same as the first restriction side opening 41 and the first passage side rotating plate 12 in the first embodiment, and the first restriction that rotates together with the first shaft 3. The side rotating plate 111 and the passing side rotating plate 112 that rotates together with the second shaft 4 are provided, but the second passing side rotating plate corresponding to the second passing side rotating plate 12 ′ of the first embodiment is provided. Absent. In addition, the second regulating-side rotating plate 111 ′ of the present embodiment has front and back surfaces that can rotate with the first shaft 3 and that are orthogonal to the shaft axial direction. The second restricting-side rotating plate 111 ′ is connected to the outer peripheral end of the first restricting-side rotating plate 111 via the connecting member 110, thereby rotating along with the first shaft 3. In the present embodiment, the connecting member 110 is integrated with the first regulating side rotating plate 111.
[0031]
Both regulating side rotating plates 111, 111 ', passing side rotating plate 112 and both coils 33, 34 are arranged in parallel in the shaft axial direction, and both regulating side rotating plates 111, 111 'and the passage-side rotating plate 112 are disposed, and the passage-side rotating plate 112 is disposed between the both regulation-side rotating plates 111 and 111'. In the present embodiment, between the first coil holder 31 and the first regulating side rotating plate 111, between the first regulating side rotating plate 111 and the passing side rotating plate 112, and between the passing side rotating plate 112 and the second regulating side rotation. A gap in the axial direction of the shaft is formed between the plate 111 ′ and between the second coil holder 32 and the second regulating side rotating plate 111 ′.
[0032]
As shown in (1) to (3) of FIG. 9, the first restriction-side opening 141 is provided in the first restriction-side rotating plate 111, and the second restriction-side opening 141 ′ is provided in the second restriction-side rotating plate 111 ′. It is formed in the same manner as the restriction side openings 41 and 41 ′ of the embodiment. Further, the passage-side opening 142 is formed in the passage-side rotating plate 112 in the same manner as the first passage-side opening 42 of the first embodiment. Note that the overlap prevention opening is not formed.
[0033]
In the shaft axial direction, the first restriction side opening 141 and the passage side opening are arranged such that the overlapping area of the first restriction side opening 141 and the passage side rotation plate 112 changes according to the relative rotation of the shafts 3 and 4. 142 is arranged so that the overlapping area changes according to the relative rotation of the shafts 3 and 4. Further, in the shaft axial direction, the second restriction side opening 141 ′ is changed so that the overlapping area between the second restriction side opening 141 ′ and the passing side rotation plate 112 changes according to the relative rotation of the shafts 3 and 4. And the passage-side opening 142 are relatively arranged so that the overlapping area changes according to the relative rotation of the shafts 3 and 4. In this embodiment, as shown in FIGS. 10 and 11, when the shafts 3 and 4 are at a detection origin position where they are not rotating relative to each other, that is, when the steering angle is zero, the respective restriction side openings 141 and 141 in the shaft axis direction. ′ Partially overlaps the passage-side opening 142.
[0034]
When the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, one edge 142a along the shaft radial direction of the passage-side opening 142 in the shaft axial direction is the circumferential direction of the shaft in the first restriction-side opening 141. The other edge 142b along the shaft radial direction of the passage side opening 142 is overlapped with the center position, and the shaft circumferential direction center position of the second restriction side opening 141 ′ is overlapped. As a result, the overlapping area between the first regulating side opening 141 and the passing side rotating plate 112 increases when both shafts 3 and 4 rotate in one direction and decreases when they rotate in the other direction. The first regulating side opening 141 and the passing side opening 142 are relatively arranged, and the overlapping area between the second regulating side opening 141 ′ and the passing side rotating plate 112 is such that the shafts 3 and 4 are relatively rotated in one direction. The second restriction-side opening 141 ′ and the passage-side opening 142 are relatively arranged so that the second restriction-side opening 141 ′ and the passage-side opening 142 are increased so as to decrease when the rotation is performed and increase when the rotation is relative. When the shafts 3 and 4 are at the detection origin position where they are not rotating relative to each other, the overlapping area of the first restriction side opening 141 and the passage side rotation plate 112, the second restriction side opening 141 'and the passage side The overlapping area with the rotating plate 112 is equal to each other. When the shafts 3 and 4 are rotated relative to each other, the absolute value of the change in the overlapping area between the first regulating side opening 141 and the passing side rotating plate 112 and the first 2 The absolute value of the change in the overlapping area between the restriction-side opening 141 ′ and the passage-side rotating plate 112 is made equal to each other.
[0035]
The first restricting side opening 141 is disposed at the passing position of the magnetic flux generated by the first coil 33, and the second restricting side opening 141 ′ is disposed at the passing position of the generated magnetic flux of the second coil 34, and the passing side rotating plate thereof. Reference numeral 112 is disposed at a position where the magnetic flux generated by the coils 33 and 34 passes. As shown by a two-dot chain line β in FIG. 8, the magnetic flux generated by the first coil 33 passes through the first coil holder 31, the first restriction-side opening 141 of the first restriction-side rotating plate 111, and the passing-side rotating plate 112. Thus, a first magnetic circuit including the first coil holder 31 and the passing-side rotating plate 112 as components is configured. Further, the magnetic flux generated by the second coil 34 passes through the second coil holder 32, the second restriction-side opening 141 ′ of the second restriction-side rotating plate 111 ′, and the passing-side rotating plate 112, so that the second coil holder 32. And the 2nd magnetic circuit containing the passage side rotating plate 12 'as a component is comprised.
[0036]
According to the above configuration, the overlapping area of the first restriction side opening 141 and the passing side rotating plate 112 and the overlapping area of the second restricting side opening 141 ′ and the passing side rotating plate 112 are such that both shafts 3 and 4 are When the two shafts 3 and 4 are relatively rotated, one is increased and the other is decreased, and the absolute values of the changes are equal to each other. Therefore, the passing magnetic flux change of the passing side rotating plate 112 according to the change of the overlapping area of the first restricting side opening 141 and the passing side rotating plate 112, and the second restricting side opening 141 ′ and the passing side rotating plate 112. Based on the difference from the passing magnetic flux change of the passing side rotating plate 112 according to the change of the overlapping area, the torque transmitted by the shafts 3 and 4 is detected by the torque detection circuit similar to the first embodiment, and the torque detection sensitivity. Can be increased. In addition, when the temperature fluctuates, the magnetic flux passing through the passing-side rotating plate 112 via the first restricting-side opening 141 is the same as the magnetic flux passing through the passing-side rotating plate 112 via the second restricting-side opening 141 ′. Therefore, the variation in the detected torque due to the temperature variation can be offset by detecting the torque based on the difference between the two passing magnetic flux changes. Therefore, it is possible to improve the detection sensitivity and at the same time compensate for the detection value variation due to the temperature change, thereby simplifying the structure and reducing costs.
Other configurations are the same as those in the first embodiment, and the same operational effects can be achieved.
[0037]
The present invention is not limited to the above embodiment. For example, the opening formed in each rotating plate is an opening whose periphery is closed in each of the above embodiments, but may be an opening opened on the outer peripheral side or the inner peripheral side of each rotating plate. Further, one end side of the first shaft 3 may be connected to the steering gear, and the other end side of the second shaft 4 may be connected to the steering wheel. Further, the structure in which the second restriction-side rotating plate, the second passage-side rotating plate, and the second coil in the first embodiment are eliminated, or the structure in which the second restriction-side rotating plate and the second coil in the second embodiment are eliminated. The torque transmitted by both shafts is detected based only on the change in the passing magnetic flux of the first passing side rotating plate in accordance with the change in the overlapping area of the first regulating side opening and the first passing side rotating plate. May be. Furthermore, the torque sensor of the present invention may be used to detect torque in devices other than the steering device.
[0038]
【The invention's effect】
According to the present invention, it is possible to provide a torque sensor that can be reduced in size, improved in sensitivity, improved in accuracy, simplified in structure, and reduced in cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a torque sensor according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part of the torque sensor according to the first embodiment of the present invention.
3 is a front view of a first regulating side rotating plate, (2) is a front view of a second passing side rotating plate, and (3) is a first passage of the torque sensor according to the first embodiment of the present invention. FIG. Front view of the side rotating plate, (4) is a front view of the second regulating side rotating plate
4 is a cross-sectional view taken along line IVa-IVa in FIG. 2, and FIG. 4 is a cross-sectional view taken along line IVb-IVb in FIG.
FIG. 5 is a cross-sectional view taken along line VV in FIG.
FIG. 6 is a diagram showing a torque detection circuit according to the embodiment of the present invention.
FIG. 7 is a cross-sectional view of a torque sensor according to a second embodiment of the present invention.
FIG. 8 is a cross-sectional view of a main part of a torque sensor according to a second embodiment of the present invention.
9 is a front view of a first regulating side rotating plate, (2) is a front view of a passing side rotating plate, and (3) is a second regulating side rotation of a torque sensor according to a second embodiment of the present invention. Front view of board
10 is a cross-sectional view taken along line Xa-Xa in FIG. 8, and FIG. 10 is a cross-sectional view taken along line Xb-Xb in FIG.
11 is a cross-sectional view taken along line XI-XI in FIG.
[Explanation of symbols]
1 Torque sensor
3 First shaft
4 Second shaft
11, 111 First regulating side rotating plate
11 ', 111' second regulating side rotating plate
12 First passage side rotating plate
112 Passing side rotating plate
12 '2nd passage side rotation board
31 First coil holder
32 Second coil holder
33 First coil
34 Second coil
41, 141 First restriction side opening
41 ', 141' Second restriction side opening
42 First passage side opening
142 Passing side opening
42 'second passage side opening
43, 43 'Overlap prevention opening

Claims

A first shaft;
A second shaft connected coaxially and elastically to the first shaft so as to be relatively rotatable;
A first regulating-side rotating plate made of a conductive non-magnetic material that can rotate with the first shaft and has front and back surfaces orthogonal to the shaft axial direction;
A first passage-side rotating plate made of a magnetic material that can rotate with the second shaft and has front and back surfaces orthogonal to the shaft axial direction;
A second passage-side rotating plate made of a magnetic material that can rotate with the first shaft and has front and back surfaces orthogonal to the shaft axial direction;
A second regulating-side rotating plate that can rotate with the second shaft and has front and back surfaces orthogonal to the shaft axial direction;
A first coil and a second coil having the same specification, each of which is composed of a conductive wire wound around a shaft axis and generates a magnetic flux so as to generate an alternating magnetic field;
Both regulating side rotating plates, both passing side rotating plates and both coils are arranged in parallel in the shaft axial direction,
Both regulating side rotating plates and both passing side rotating plates are arranged between both coils, both passing side rotating plates are arranged between both regulating side rotating plates, and between the first coil and the first passing side rotating plate. The first regulating side rotating plate and the second passing side rotating plate are arranged, and the second regulating side rotating plate and the first passing side rotating plate are arranged between the second coil and the second passing side rotating plate,
A first restriction side opening is formed in the first restriction side rotating plate,
A second restriction side opening is formed in the second restriction side rotating plate,
The first passage side rotating plate is formed with a first passage side opening and an overlap prevention opening in the shaft axial direction of the second restriction side opening and the first passage side rotating plate,
The second passage side rotating plate is formed with a second passage side opening and an overlap prevention opening in the shaft axial direction of the first regulation side opening and the second passage side rotating plate,
The first restriction side opening, the overlap prevention opening of the second passage side rotating plate, and the first passage side rotating plate are arranged at a passage position of the magnetic flux generated by the first coil,
The second restriction side opening, the overlap prevention opening of the first passing side rotating plate, and the second passing side rotating plate are arranged at a passage position of the magnetic flux generated by the second coil,
In the shaft axis direction, the overlapping area of the first restriction side opening and the first passage side rotating plate increases when both shafts rotate relative to one direction and decreases when they rotate relative to each other direction. The first restriction side opening and the first passage side opening are relatively arranged,
In the shaft axis direction, the overlapping area between the second restriction side opening and the second passing side rotating plate decreases when both shafts rotate in one direction and increases when they rotate in the other direction. The second restriction side opening and the second passage side opening are relatively arranged,
When the shafts are at the detection origin position where they are not rotating relative to each other, the overlapping area of the first restriction side opening and the first passing side rotating plate, and the overlapping of the second restriction side opening and the second passing side rotating plate The areas are equal to each other,
At the time of relative rotation of both shafts, the absolute value of the change in the overlap area between the first restriction side opening and the first passage side rotation plate and the overlap area between the second restriction side opening and the second passage side rotation plate The absolute values of the changes are equal to each other,
The change of the passing magnetic flux of the first passing side rotating plate according to the change of the overlapping area of the first restricting side opening and the first passing side rotating plate, and the second restricting side opening and the second passing side rotating plate A torque sensor that detects a torque transmitted by both shafts based on a difference from a change in passing magnetic flux of the second passing side rotating plate in accordance with a change in overlapping area.

2. The torque sensor according to claim 1, wherein the thickness dimension of the coil is less than the dimension of each opening in the shaft radial direction, and the inner and outer circumferences of the coil are disposed between the inner and outer circumferences of the respective openings .

A coil holder made of a magnetic material for holding the coil;
The coil holder includes a cylindrical outer peripheral portion surrounding the outer peripheral side of the coil, a cylindrical inner peripheral portion surrounding the inner peripheral side of the coil, and a side away from the rotating plate in the outer peripheral portion and the inner peripheral portion. A portion connecting one end of the
In the shaft radial direction, the distance from the shaft axis to the inner peripheral edge of the coil holder is less than the distance from the shaft axis to the inner peripheral edge of each opening,
The torque sensor according to claim 2 , wherein a distance from the shaft axis to the outer peripheral end of each rotating plate is less than a distance from the shaft axis to the outer peripheral end of the coil holder in the shaft radial direction .

Each opening has a shape along a quadrilateral having a pair of edges along the shaft radial direction and a pair of edges along the circumference centered on the axis of both shafts. The torque sensor according to item 1 .

Each rotating plate has a disk shape coaxial with both shafts,
Each opening torque sensor according to any one among claims 1 to 4, formed with a plurality to parallel at intervals in the circumferential direction of the shaft to the rotation plate.