JP4241951B2 - Power roller bearing for toroidal-type continuously variable transmission - Google Patents

Power roller bearing for toroidal-type continuously variable transmission Download PDF

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JP4241951B2
JP4241951B2 JP34643397A JP34643397A JP4241951B2 JP 4241951 B2 JP4241951 B2 JP 4241951B2 JP 34643397 A JP34643397 A JP 34643397A JP 34643397 A JP34643397 A JP 34643397A JP 4241951 B2 JP4241951 B2 JP 4241951B2
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power roller
bearing
continuously variable
outer ring
variable transmission
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JPH11172371A (en
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雅由 清水屋
伸夫 後藤
宣晶 三田村
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NSK Ltd
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NSK Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、例えば自動車の変速機として使用されるトロイダル型無段変速機を構成するパワーローラ軸受のうち、特に耐熱性及び耐久性を向上させたものに関する。
【0002】
【従来の技術】
主に自動車用の変速機として従来より研究が進められているトロイダル型無段変速機は、互いに対向する面がそれぞれ円弧形状の凹断面を有する入力ディスク及び出力ディスクと、これらのディスク間に挟持される回転自在なパワーローラとを組み合わせた構造のトロイダル変速機構を備えている。入力ディスクは、トルク入力軸方向への移動が可能なようにトルク入力軸に対して駆動結合され、一方出力ディスクは、トルク入力軸に対して相対的に回転可能かつ入力ディスクから離れる方向への移動が制限されるように入力ディスクと対向して取り付けられる。
【0003】
上述のようなトロイダル型変速機構においては、入力ディスクが回転するとパワーローラを介して出力ディスクが逆回転するため、トルク入力軸に入力された回転運動は、逆方向の回転運動として出力ディスクへと伝達されて取り出される。この際、パワーローラの周面が入力ディスクの外周付近と出力ディスクの中心付近とにそれぞれ当接するようにパワーローラの回転軸の傾斜角度を変化させることでトルク入力軸から出力ギアへの増速が行なわれ、これとは逆に、パワーローラの周面が入力ディスクの中心付近と出力ディスクの外周付近とにそれぞれ当接するようにパワーローラの回転軸の傾斜角度を変化させることでトルク入力軸から出力ギアへの減速が行なわれる。さらに両者の中間の変速比についても、パワーローラの回転軸の傾斜角度を適当に調節することにより、ほぼ無段階に得ることができる。パワーローラは、トロイダル型無段変速機のケーシングと結合したトラニオンによって支持されており、パワーローラの回転軸の傾斜角度は、トラニオンをトルク入力軸に対して捩じれの位置関係にある枢軸を中心として揺動回転させることで調節される。
【0004】
トロイダル型無段変速機の動作に伴って高速回転するパワーローラに対しては、入力ディスク及び出力ディスクとの間の摩擦接触を維持するための押圧力が、トルク入力軸方向に沿って常時作用しているため、パワーローラとトラニオンとの間にスラスト回転軸受等のパワーローラ軸受を配置することで、パワーローラから加わる荷重を支承している。パワーローラ軸受は、図1に示すように、パワーローラ1及び軸受外輪2と複数個の転動体3とから構成され、軸受内輪として機能するパワーローラ1の背面1a上、及び軸受外輪2のパワーローラ1と対向する面2a上には、それぞれ円周方向に亘る円環形状の軌道溝4、4が形成される。転動体3は、パワーローラ1及び軸受外輪2の両軌道溝4、4内に挟持された状態で円周方向に沿って転動することで、パワーローラ1の回転を円滑に行わせる。パワーローラ1及び軸受外輪2の両対向面1a、2a間には、各転動体3の間隔を適切に保ちつつ転動可能に保持して両軌道溝4、4から脱落しないよう案内する中空円盤形状の保持器5が配置されており、この保持器5上に形成された厚さ方向へと貫通する複数個のポケット孔6内にそれぞれ転動体3が配設される。ポケット孔6の形状は、ここで示した例では転動体3が玉であることから円形状となっているが、例えば転動体がころである場合には長方形というように、各転動体の断面形状に応じて適宜変更できる。
【0005】
【発明が解決しようとする課題】
トロイダル型無段変速機のパワーローラ軸受においては、大きなトラクション力を得るために高いトラクション係数を有する潤滑油が使用され、各転動体に作用する面圧が通常の軸受よりも高いことから、各転動体と両軌道溝との接触部分に転がり摩擦による発熱が生じて、軌道面の温度が上昇する。また、トロイダル型無段変速機を含む自動車用の変速機では、潤滑油の循環系への異物混入が起こりやすい。したがって、トロイダル型無段変速機のパワーローラ軸受には、温度変化及び異物混入の面で、通常の軸受よりも遥かに厳しい環境における耐久性が要求されることになる。
【0006】
一般にトロイダル型無段変速機で生じた熱は、各回転部分やしゅう動面等を潤滑するための潤滑油により冷却される。この際、トロイダル型無段変速機の外部に設けた潤滑ポンプからトルク入力軸の中心部に穿設されている油供給孔を通じて導入された潤滑油は、油供給孔の壁面に形成された油路から遠心力にしたがって外径方向へと順に圧送されていくため、パワーローラ近傍に供給された潤滑油は、まずトルク入力軸中心部の油供給孔に最も近いパワーローラ軸受の内輪付近、次いで各転動体及び保持器、その後パワーローラ軸受の外輪という順序で冷却を行う。また、トロイダル型無段変速機の動作中に常時回転するパワーローラと一体的に結合しているパワーローラ軸受内輪の温度分布は比較的均一に保たれるが、トラニオンの中心部に設けられた凹部に嵌め込まれていて、トロイダル型無段変速機の動作中にも回転を伴わないパワーローラ軸受外輪では、潤滑油が細部にまで行き渡りにくく、温度分布が不均一になる傾向が強い。
【0007】
以上の理由により、トロイダル型無段変速機のパワーローラ軸受の外輪では、パワーローラ軸受内輪に比べて冷却効率が劣り、作動時の温度条件がより過酷なものとなることは避けられない。その結果、転動面の温度の急激な上昇を招いて、早期剥離や転動面の損壊を生じさせる危険性が高くなる。したがって、トロイダル型無段変速機のパワーローラ軸受においては、少なくとも外輪の材料として、析出硬化系やオーステナイト系などの高い耐熱性を備えた合金を用いることが重要である。
【0008】
一般に、温度条件の厳しい環境で使用される金属材料の耐熱性能及び強度を確保するためには、金属組織中の残留オーステナイト量を極力減少させた析出硬化系の合金材料の使用が効果的である。例えば、軸受材料として多く用いられるSUSやM50といった析出硬化系の合金では、組織中の残留オーステナイト量が通常ほぼ0%にまで低減されているため高温強度が優れており、激しい温度変化に対する寸法安定性を確保することができる。
【0009】
一方、異物混入環境における軸受の寿命維持に関しては、材料の金属組織中に残留するオーステナイトの有効性が知られており、浸炭鋼や軸受鋼に焼入処理や焼戻し処理等を施すことで残留オーステナイト量を増大させたオーステナイト系の耐熱鋼材の使用例がある。また、オーステナイト系耐熱鋼は、同時に高い高温強度を有している。ただし、浸炭鋼や軸受鋼の残留オーステナイトは、熱的に不安定であり、急激な冷却や塑性変形によってマルテンサイト等の他の組織へと変態する際に容易に分解されることから、著しい温度変化を伴うトロイダル型無段変速機の作動環境下で有効量を維持することが難しい。したがって、オーステナイト系耐熱鋼は、トロイダル型無段変速機の軸受の材料として使用された場合に、期待される寿命維持効果を十分に発揮できない。
【0010】
この結果、前述のように高温かつ異物混入環境での安定作動が求められるトロイダル型無段変速機のパワーローラ軸受においては、高温耐久性を向上させるために析出硬化型の合金材料を使用しても、オーステナイトの欠如により異物混入環境で要求される寿命を維持できない。一方、異物耐久性を確保するために残留オーステナイト量を増大させた合金を使用したとしても、オーステナイトの分解により高温耐久性の劣化が進行するため、結果的に期待される長寿命を達成できない。さらに後者の場合、作動中に大きな振動を伴うパワーローラにおいてオーステナイトの分解が進行すると、相変態に伴う表面起伏が生じて、パワーローラの転動面に面あれが起きることがあり、パワーローラの回転にムラを生じさせる原因となる等、かえって装置の安定性を妨げることにもなる。そこで、トロイダル型無段変速機のパワーローラ軸受の材料としては、残留オーステナイト量が多く、かつ激しい温度変化を受けてもこの残留オーステナイトが分解されにくい性質を備えた合金元素を含んでいることが望ましい。
【0011】
本発明は、上述のような事情によりなされたものであり、材料となる鋼材中の残留オーステナイト量を増大させ、かつ増大されたオーステナイトの分解を遅延させる効果を高めることにより、軸受を構成するパワーローラ及び軸受外輪の耐熱性及び高温強度を従来よりも高めて軸受の寿命向上を図ったトロイダル型無段変速機のパワーローラ軸受の提供を目的とする。
【0012】
【課題を解決するための手段】
本発明は、トルク入力軸に取着された互いに対向する入力ディスク及び出力ディスクに当接して駆動力を伝達するパワーローラと前記トルク入力軸に対して捩じれの位置関係にある枢軸によってケーシングと揺動自在に結合したトラニオンが支持する軸受外輪との間に挟持される複数個の転動体と、厚さ方向に貫通する複数個のポケット孔内に前記複数個の転動体を保持して前記複数個の転動体が軌道溝から脱落することを防止する保持器とを備えており、前記パワーローラ及び前記軸受外輪上にそれぞれ形成された円環形状の軌道溝内を転動する前記複数個の転動体によって、前記パワーローラと前記トラニオンとを回転自在に結合すると共に、前記パワーローラに加わるスラスト荷重を受け止めるトロイダル型無段変速機のパワーローラ軸受に関するものであり、本発明の上記目的は、前記パワーローラ及び前記軸受外輪の材料が、低炭素鋼または中炭素鋼の含有量で炭素を含有し、浸炭又は浸炭窒化処理と焼入処理が施された後に、210℃以上270℃以下で焼戻し処理が施された浸炭鋼であり、かつ、少なくとも前記軸受外輪の材料が、残留オーステナイトの分解を遅延させる合金元素であるSiを0.53重量%以上1.42重量%以下、およびMoを0.55重量%以上1.46重量%以下含むことによって達成される。
【0013】
【発明の実施の形態】
本発明のトロイダル型無段変速機のパワーローラ軸受は、パワーローラ及び軸受外輪の材料として使用する鋼材に特徴を有するものであり、材料以外の部分に関しては従来からあるトロイダル型無段変速機のパワーローラ軸受と同様に構成することができる。
【0014】
本発明のトロイダル型無段変速機のパワーローラ軸受では、低炭素または中炭素の浸炭鋼を材料とすることで、温度変化に対する耐久性が向上し、また同時に、少なくとも軸受外輪の材料が残留オーステナイトの分解を遅延させる合金元素を含むようにすることで、温度変化に対する耐久性の低下が防止される。これにより、パワーローラ軸受の寿命が増大して、トロイダル型無段変速機全体の信頼性及び耐久性が向上する。
【0015】
パワーローラ及び軸受外輪の材料として浸炭鋼を用いることにより、合金中の固溶炭素Cの比率を上昇させると共に、γR の量を増加させることができる。浸炭鋼は、鋼材に対して浸炭・焼入処理を施した後、焼戻し処理を施すことで得られるが、合金に含まれる残留オーステナイトを安定化させるためには、焼戻し処理が施される際の焼戻し温度を少なくとも200℃以上にする必要がある。一方、焼戻し温度を必要以上に高くすると、かえって合金組織中に残留するオーステナイトの量が減少するため、焼戻し温度は270℃を越えないことが望ましい。したがって、浸炭・焼入処理後の焼戻し処理を200℃〜270℃の範囲で施すことが、本発明のトロイダル型無段変速機のパワーローラ軸受に用いられる材料の焼戻し条件となる。さらに可能ならば、γR の分解を遅延させる効果が得られる浸炭窒化処理を浸炭処理の代わりに施すとよい。
【0016】
また、軸受外輪の材料に用いられる鋼材に含まれる合金元素は、例えばシリコンSiやモリブデンMoのように、残留オーステナイトの分解を遅延させる効果を有すると共に、鋼材の高温強度を向上させる性質を備えていることが望ましい。ただし、シリコンSiやモリブデンMoのような合金元素を鋼材に混入する場合、0.5%以下の混入比率では十分な遅延効果を発揮させることができず、一方、1.5%以上の比率で混入しても、材料の加工性や熱処理特性の面で生じる障害が大きくなり、製造コストや加工コストが上昇する。したがって、シリコンSiやモリブデンMoを0.5%〜1.5%の範囲で混入することが、本発明のトロイダル型無段変速機のパワーローラ軸受に用いられる材料の合金条件となる。
【0017】
図2に示す表には、シリコンSi、モリブデンMoの混入比率や、焼戻し温度を変化させて得られた材料No.1〜材料No.14の軸受材料が列挙されている。これらのうち材料No.1〜材料No.8は、本発明のトロイダル型無段変速機のパワーローラ軸受の実施例を構成するパワーローラ及び軸受外輪の材料として用いられる合金の一例であり、各合金元素の混入比率と浸炭・焼入処理後の焼戻し処理における焼戻し温度とが、それぞれ上記本発明の合金条件及び焼戻し条件を満たすようにしている。
【0018】
材料No.1及び材料No.2は、シリコンSiの混入比率を変化させた例であり、材料No.1では本発明の合金条件の下限値に近い0.53%、材料No.2では本発明の合金条件の上限値に近い1.42%のシリコンSiがそれぞれ混入されている。材料No.3及び材料No.4は、モリブデンMoの混入比率を変化させた例であり、材料No.3では本発明の合金条件の下限値に近い0.55%、材料No.4では本発明の合金条件の上限値に近い1.46%のモリブデンMoがそれぞれ混入されている。また、これら材料No.1〜材料No.4では、共に本発明の焼戻し条件を満たす210℃の焼戻し処理が施されている。
【0019】
材料No.5〜材料No.7は、浸炭・焼入処理後の焼戻し温度を変化させた例であり、材料No.5では本発明の焼戻し条件の下限値に近い210℃、材料No.6では本発明の焼戻し条件の中間値である240℃、材料No.7では本発明の焼戻し条件の上限値に近い270℃の焼戻し処理がそれぞれ施されている。また、これら材料No.5〜材料No.7では、共に本発明の合金条件を満たす0.98%のシリコンSi及びモリブデンMoがそれぞれ混入されている。
【0020】
材料No.8は、浸炭処理の代わりに浸炭窒化処理が施された例であり、共に本発明の合金条件を満たす0.98%のシリコンSi及びモリブデンMoが混入され、また本発明の焼戻し条件を満たす210℃の焼戻し処理が施されている。
【0021】
一方、材料No.9〜材料No.14は、上述した材料No.1〜材料No.8による本発明の実施例と比較するための比較例を構成するパワーローラ及び軸受外輪の材料として用いられる合金の一例であり、各合金元素の混入比率や焼戻し温度が本発明の合金条件及び焼戻し条件を満足していない。
【0022】
材料No.9及び材料No.10は、シリコンSi及びモリブデンMoの混入比率が本発明の合金条件を満たさない例であり、材料No.9では本発明の合金条件の下限値よりも低い0.42%のシリコンSiが、材料No.10では本発明の合金条件の下限値よりも低い0.45%のモリブデンMoがそれぞれ混入されている。また、これら材料No.9及び材料No.10では、共に本発明の焼戻し条件を満たす210℃の焼戻し処理が施されている。
【0023】
材料No.11及び材料No.12は、浸炭・焼入処理後の焼戻し温度が本発明の焼戻し条件を満たさない例であり、材料No.11では本発明の焼戻し条件の下限値よりも低い180℃、材料No.12では本発明の焼戻し条件の上限値よりも高い280℃の焼戻し処理がそれぞれ施されている。また、これら材料No.11及び材料No.12では、共に本発明の合金条件を満たす0.98%のシリコンSi及びモリブデンMoがそれぞれ混入されている。
【0024】
材料No.13は、浸炭・焼入処理の代わりにずぶ焼(無心焼入)処理が施された例であり、共に本発明の合金条件を満たす0.85%のシリコンSiと0.95%のモリブデンMoとが混入され、本発明の焼戻し条件を満たす240℃の焼戻し処理が施されている。
【0025】
材料No.14は、通常の浸炭鋼(クロムモリブデン鋼:SCM435)であり、共に本発明の合金条件よりも低い0.25%のシリコンSiと0.15%のモリブデンMoとが混入され、本発明の焼戻し条件を満たす210℃の焼戻し処理が施されている。
【0026】
図3は、図2の表に記載された材料No.1〜材料No.14をパワーローラ及び軸受外輪の材料とする軸受記号A〜軸受記号Pのパワーローラ軸受について実施した耐久試験の結果をまとめた表であり、各パワーローラ軸受の破損までの寿命値、破損部位、及び低荷重で一定時間回転させたときに生じる振動の程度が記載されている。
【0027】
軸受記号A〜軸受記号Jのパワーローラ軸受は、それぞれ材料No.1〜材料No.8の合金を材料として構成された軸受外輪を備えており、本発明のパワーローラ軸受の実施例にあたる。これらのうち軸受記号A〜軸受記号Hのパワーローラ軸受では、材料No.14の通常浸炭鋼を材料とした軸受内輪(パワーローラ)が組み合わされており、各軸受外輪のみが本発明の合金条件及び焼戻し条件を満たしている。軸受記号I及び軸受記号Jのパワーローラ軸受では、それぞれ材料No.5及び材料No.8の合金を材料とした軸受内輪(パワーローラ)が組み合わされており、軸受外輪及び軸受内輪(パワーローラ)が共に本発明の合金条件及び焼戻し条件を満たしている。
【0028】
一方、軸受記号K〜軸受記号Pのパワーローラ軸受は、それぞれ材料No.9〜材料No.14の合金を材料として構成された軸受外輪と、材料No.14の通常浸炭鋼を材料とした軸受内輪(パワーローラ)とを備えており、従来の構成に基づく比較例にあたる。これらのうち軸受記号K〜軸受記号Oのパワーローラ軸受では、各軸受外輪が本発明の合金条件及び焼戻し条件のいずれか一方を満たしておらず、各軸受内輪(パワーローラ)は本発明の合金条件及び焼戻し条件の双方を満たしていない。軸受記号Pのパワーローラ軸受では、軸受外輪及び軸受内輪(パワーローラ)の材料が共に材料No.14の通常浸炭鋼となっており、どちらも本発明の合金条件及び焼戻し条件を満たしていない。この軸受記号Pのパワーローラ軸受は、従来の浸炭鋼製軸受と同等のものである。
【0029】
本発明の実施例に相当する軸受記号A〜軸受記号Jのパワーローラ軸受では、24.0〜72.1の範囲の寿命値が得られており、いずれにおいても低荷重回転で発生する振動は許容範囲内にある。また、軸受外輪のみが本発明の合金条件及び焼戻し条件を満たしている軸受記号A〜軸受記号Hのパワーローラ軸受では、いずれも軸受内輪(パワーローラ)が軸受外輪よりも先に破損したが、軸受外輪及び軸受内輪(パワーローラ)が共に本発明の合金条件及び焼戻し条件を満たしている軸受記号I及び軸受記号Jのパワーローラ軸受では、どちらも軸受外輪が軸受内輪(パワーローラ)よりも先に破損した。
【0030】
これに対して、従来の構成に基づく比較例に相当する軸受記号K〜軸受記号Pのパワーローラ軸受のうち、軸受記号Mのパワーローラ軸受以外では、いずれも低荷重回転で発生する振動が許容範囲内にあるものの、5.5〜8.4の範囲の寿命値しか得られていない。一方、軸受記号Mのパワーローラ軸受では、本発明の実施例に相当するパワーローラ軸受の一部を上回る30.1の寿命値が得られたが、低荷重回転で発生する振動が許容範囲を越えてしまっている。また、これらの軸受記号K〜軸受記号Pのパワーローラ軸受では、いずれも軸受外輪が軸受内輪(パワーローラ)よりも先に破損した。
【0031】
この結果、パワーローラ及び軸受外輪の材料として中炭素又は高炭素の浸炭鋼を使用すること、及び残留オーステナイト量が多くかつ残留オーステナイトの分解を遅延させる合金素材を本発明の合金条件を満たす範囲で含有する鋼材を少なくとも外輪の材料として使用することが、パワーローラ軸受の寿命延長について効果的であることが確認できる。また、本発明のトロイダル型無段変速機のパワーローラ軸受の寿命延長効果は、材料となる鋼材に対して、シリコンSiやモリブデンMoが本発明の合金条件の上限値に近い比率で混入され、浸炭処理の代わりに浸炭窒化処理が施され、かつ本発明の焼戻し条件の下限値に近い温度の焼戻し処理が施される場合に最大となることがわかる。
【0032】
さらに、本発明の合金条件及び焼戻し条件を満たしている鋼材を材料とする外輪に対して、本発明の合金条件及び焼戻し条件を満たしている鋼材を材料とする軸受内輪(パワーローラ)を組み合わせた場合、通常の浸炭鋼製の軸受内輪(パワーローラ)との組み合わせと比較して、寿命値が50%前後も延長され、浸炭処理の代わりに浸炭窒化処理が施された鋼材を軸受外輪の材料とした場合にも、やはり約50%の寿命延長効果が認められることが読み取れる。このため、最も優れた寿命延長効果を持たせるためには、本発明の合金条件及び焼戻し条件を満たしている鋼材を軸受内輪(パワーローラ)の材料としても使用し、この鋼材に対して浸炭処理の代わりに浸炭窒化処理を施した軸受記号Jのようなパワーローラ軸受を使用することが望ましい。
【0033】
図4は、上述の耐久試験結果のうち軸受記号B、軸受記号M、軸受記号Iの各パワーローラ軸受について計測された振動加速度値を、数値及びグラフにより示したものである。軸受記号Bのパワーローラ軸受は、本発明の合金条件及び焼戻し条件を満たしている軸受外輪と本発明の合金条件及び焼戻し条件を満たしていない通常の浸炭鋼製の軸受内輪(パワーローラ)とを組み合わせた例であり、39.1の寿命値と2.8Gの振動加速度値が得られている。軸受記号Mのパワーローラ軸受は、本発明の焼戻し条件を満たしていない軸受外輪と通常の浸炭鋼製の軸受内輪(パワーローラ)とを組み合わせた例であり、30.1の寿命値と7.3Gの振動加速度値が得られている。軸受記号Iのパワーローラ軸受は、共に本発明の合金条件及び焼戻し条件を満たしている軸受外輪及び軸受内輪(パワーローラ)を組み合わせた例であり、50.2の寿命値と3.5Gの振動加速度値が得られている。
【0034】
この図4には、本発明の焼戻し条件の下限値よりも低い温度の焼戻し処理が施された鋼材を軸受外輪の材料として使用した場合には、許容範囲を超える振動加速度値がパワーローラに発生することが示されている。パワーローラの振動は、トロイダル型無段変速機の円滑な変速動作を妨げるばかりでなく、トロイダル型変速機構やトロイダル型無段変速機全体の耐久性及び信頼性を低下させる原因にもなる。そのため、焼戻し処理における焼戻し温度を本発明の焼戻し条件の下限値よりも高くすることが、トロイダル型無段変速機の動作を安定させるために極めて重要である。
【0035】
【発明の効果】
本発明のトロイダル型無段変速機のパワーローラ軸受によれば、材料となる鋼材中の残留オーステナイト量を増大させ、かつ増大されたオーステナイトの分解を遅延させる効果を高めることにより、温度変化が激しい環境における高い耐熱性及び強度が備わるようになるため、パワーローラ軸受の寿命が向上する。またその結果、トロイダル型無段変速機全体の耐久性及び信頼性を高めることができる。
【図面の簡単な説明】
【図1】トロイダル型無段変速機のパワーローラ軸受の一例を示した横断面図である。
【図2】シリコンSi及びモリブデンMoの混入比率や、焼戻し温度を変化させて得られた軸受材料が列挙された表である。
【図3】図2の表に記載された各鋼材をパワーローラ及び軸受外輪の材料とするパワーローラ軸受について実施した耐久試験の結果をまとめた表である。
【図4】図3のパワーローラ軸受の一部について実施した耐久試験の結果を示す説明図である。
【符号の説明】
1 パワーローラ
1a パワーローラ背面
2 軸受外輪
2a 軸受外輪対向面
3 転動体
4 軌道溝
5 保持器
6 ポケット孔
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power roller bearing that constitutes a toroidal-type continuously variable transmission used, for example, as a transmission of an automobile, and particularly to one that has improved heat resistance and durability.
[0002]
[Prior art]
A toroidal-type continuously variable transmission, which has been studied mainly as a transmission for automobiles, is sandwiched between an input disk and an output disk, each of which has an arcuate concave cross section on the surfaces facing each other. A toroidal transmission mechanism having a structure combined with a rotatable power roller. The input disk is drivingly coupled to the torque input shaft so as to be movable in the direction of the torque input shaft, while the output disk is rotatable relative to the torque input shaft and away from the input disk. It is mounted opposite the input disk so that movement is restricted.
[0003]
In the toroidal transmission mechanism as described above, when the input disk rotates, the output disk rotates in reverse via the power roller. Therefore, the rotational motion input to the torque input shaft is converted to the output disk as a reverse rotational motion. It is transmitted and taken out. At this time, the speed of rotation from the torque input shaft to the output gear is increased by changing the inclination angle of the rotating shaft of the power roller so that the peripheral surface of the power roller is in contact with the vicinity of the outer periphery of the input disk and the center of the output disk. On the contrary, the torque input shaft is changed by changing the tilt angle of the rotation shaft of the power roller so that the peripheral surface of the power roller is in contact with the vicinity of the center of the input disk and the vicinity of the outer periphery of the output disk. To the output gear. Further, an intermediate gear ratio can be obtained almost steplessly by appropriately adjusting the inclination angle of the rotating shaft of the power roller. The power roller is supported by a trunnion connected to the casing of the toroidal continuously variable transmission, and the tilt angle of the rotation axis of the power roller is centered on the pivot that is twisted relative to the torque input shaft. It is adjusted by swinging and rotating.
[0004]
For the power roller that rotates at high speed as the toroidal-type continuously variable transmission operates, the pressing force to maintain the frictional contact between the input disk and the output disk always acts along the direction of the torque input shaft. Therefore, a load applied from the power roller is supported by disposing a power roller bearing such as a thrust rotary bearing between the power roller and the trunnion. As shown in FIG. 1, the power roller bearing includes a power roller 1, a bearing outer ring 2, and a plurality of rolling elements 3. The power roller bearing functions as a bearing inner ring, on the back surface 1 a of the power roller 1, and the power of the bearing outer ring 2. On the surface 2 a facing the roller 1, ring-shaped track grooves 4, 4 are formed in the circumferential direction. The rolling element 3 rolls along the circumferential direction in a state of being sandwiched between both raceway grooves 4 and 4 of the power roller 1 and the bearing outer ring 2, thereby smoothly rotating the power roller 1. A hollow disk between the opposing faces 1a and 2a of the power roller 1 and the bearing outer ring 2 is held so as to be able to roll while keeping the spacing of the rolling elements 3 appropriately and guided so as not to drop off from both raceway grooves 4 and 4. A cage 5 having a shape is disposed, and the rolling elements 3 are respectively disposed in a plurality of pocket holes 6 formed on the cage 5 and penetrating in the thickness direction. The shape of the pocket hole 6 is circular because the rolling element 3 is a ball in the example shown here. For example, when the rolling element is a roller, the shape of the pocket hole 6 is a cross section of each rolling element. It can be appropriately changed according to the shape.
[0005]
[Problems to be solved by the invention]
In the power roller bearing of the toroidal-type continuously variable transmission, a lubricating oil having a high traction coefficient is used to obtain a large traction force, and the surface pressure acting on each rolling element is higher than that of a normal bearing. Heat generation due to rolling friction occurs at the contact portion between the rolling element and both raceway grooves, and the temperature of the raceway surface rises. Further, in a transmission for an automobile including a toroidal type continuously variable transmission, foreign matter is likely to be mixed into the circulation system of the lubricating oil. Therefore, the power roller bearing of the toroidal-type continuously variable transmission is required to have durability in a much harsher environment than a normal bearing in terms of temperature change and contamination with foreign matter.
[0006]
In general, heat generated in the toroidal type continuously variable transmission is cooled by lubricating oil for lubricating each rotating portion, sliding surface, and the like. At this time, the lubricating oil introduced from the lubrication pump provided outside the toroidal type continuously variable transmission through the oil supply hole formed in the center of the torque input shaft is the oil formed on the wall surface of the oil supply hole. Since the oil is sequentially pumped from the road in the outer diameter direction according to the centrifugal force, the lubricating oil supplied to the vicinity of the power roller is first near the inner ring of the power roller bearing closest to the oil supply hole at the center of the torque input shaft, and then Cooling is performed in the order of each rolling element and cage, and then the outer ring of the power roller bearing. In addition, the temperature distribution of the inner ring of the power roller bearing that is integrally coupled with the power roller that always rotates during the operation of the toroidal type continuously variable transmission is kept relatively uniform, but it is provided at the center of the trunnion. In a power roller bearing outer ring that is fitted in a recess and does not rotate even during operation of the toroidal type continuously variable transmission, the lubricating oil is difficult to spread to details and the temperature distribution tends to be uneven.
[0007]
For the above reasons, it is inevitable that the outer ring of the power roller bearing of the toroidal-type continuously variable transmission is inferior in cooling efficiency to the inner ring of the power roller bearing, and the temperature conditions during operation are more severe. As a result, the temperature of the rolling surface is suddenly increased, and the risk of causing early peeling and damage to the rolling surface is increased. Therefore, in a power roller bearing of a toroidal-type continuously variable transmission, it is important to use an alloy having high heat resistance such as precipitation hardening type or austenite type as a material of at least the outer ring.
[0008]
In general, in order to ensure the heat resistance performance and strength of a metal material used in an environment with severe temperature conditions, it is effective to use a precipitation hardening type alloy material in which the amount of retained austenite in the metal structure is reduced as much as possible. . For example, precipitation hardened alloys such as SUS and M50, which are often used as bearing materials, have excellent high temperature strength because the amount of retained austenite in the structure is usually reduced to almost 0%, and dimensional stability against severe temperature changes. Sex can be secured.
[0009]
On the other hand, regarding the maintenance of bearing life in an environment containing foreign matter, the effectiveness of austenite remaining in the metal structure of the material is known, and residual austenite can be obtained by subjecting carburized steel and bearing steel to quenching and tempering. There is an example of using an austenitic heat-resistant steel material with an increased amount. In addition, austenitic heat-resistant steel has high high-temperature strength at the same time. However, the retained austenite of carburized steel and bearing steel is thermally unstable and is easily decomposed when transformed into other structures such as martensite by rapid cooling or plastic deformation. It is difficult to maintain an effective amount under the operating environment of a toroidal continuously variable transmission with changes. Therefore, the austenitic heat resistant steel cannot sufficiently exhibit the expected life maintenance effect when used as a bearing material for a toroidal type continuously variable transmission.
[0010]
As a result, in the power roller bearings of toroidal type continuously variable transmissions that are required to operate stably in a high temperature and foreign substance mixed environment as described above, a precipitation hardening type alloy material is used in order to improve high temperature durability. However, due to the lack of austenite, it is impossible to maintain the required life in a foreign matter mixed environment. On the other hand, even if an alloy with an increased amount of retained austenite is used in order to ensure the durability of foreign matter, the high temperature durability deteriorates due to the decomposition of austenite, and as a result, the expected long life cannot be achieved. Furthermore, in the latter case, when the austenite decomposition proceeds in the power roller with large vibration during operation, surface undulations may occur due to phase transformation, and the rolling surface of the power roller may be roughened. On the contrary, the stability of the apparatus is hindered, for example, causing unevenness in rotation. Therefore, the material of the power roller bearing of the toroidal type continuously variable transmission includes an alloy element having a large amount of retained austenite and a property that the retained austenite is not easily decomposed even when subjected to severe temperature changes. desirable.
[0011]
The present invention has been made under the circumstances as described above, and increases the amount of retained austenite in the steel material and increases the effect of delaying the increased decomposition of austenite. It is an object of the present invention to provide a power roller bearing for a toroidal type continuously variable transmission in which the heat resistance and high temperature strength of the roller and the outer ring of the bearing are increased as compared with the conventional one to improve the life of the bearing.
[0012]
[Means for Solving the Problems]
According to the present invention, a casing and a casing are shaken by a power roller that contacts an input disk and an output disk facing each other, which are attached to a torque input shaft, and transmits a driving force, and a pivot that is twisted with respect to the torque input shaft. A plurality of rolling elements sandwiched between a bearing outer ring supported by a movably coupled trunnion, and a plurality of the rolling elements held in a plurality of pocket holes penetrating in the thickness direction. A plurality of rolling elements that prevent the rolling elements from falling off the raceway grooves, and that roll in the annular raceway grooves respectively formed on the power roller and the bearing outer ring. A power roller of a toroidal continuously variable transmission that rotatably couples the power roller and the trunnion by a rolling element and receives a thrust load applied to the power roller. Relates receive, the object of the present invention, the material of the power roller and the bearing outer ring, contains carbon in a content of low carbon steel or medium carbon steel, carburized or carbonitrided and quenching treatment is Carburized steel that has been tempered at 210 ° C. or higher and 270 ° C. or lower after being applied , and at least the material of the outer ring of the bearing is 0.53 weight percent of Si, which is an alloy element that delays decomposition of residual austenite. % Or more and 1.42% by weight or less and Mo is contained by 0.55% by weight or more and 1.46% by weight or less .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The power roller bearing of the toroidal type continuously variable transmission of the present invention is characterized by the steel material used as the material of the power roller and the bearing outer ring, and the parts other than the material are those of the conventional toroidal type continuously variable transmission. The power roller bearing can be configured similarly.
[0014]
In the power roller bearing of the toroidal type continuously variable transmission according to the present invention, durability against temperature change is improved by using low carbon or medium carbon carburized steel, and at the same time, at least the material of the bearing outer ring is retained austenite. By including an alloy element that delays the decomposition of the metal, a decrease in durability against a temperature change is prevented. Thereby, the life of the power roller bearing is increased, and the reliability and durability of the entire toroidal type continuously variable transmission are improved.
[0015]
By using carburized steel as a material for the power roller and the bearing outer ring, the ratio of solute carbon C in the alloy can be increased and the amount of γ R can be increased. Carburized steel is obtained by carburizing and quenching the steel material, followed by tempering treatment. To stabilize the retained austenite contained in the alloy, The tempering temperature needs to be at least 200 ° C. or higher. On the other hand, when the tempering temperature is increased more than necessary, the amount of austenite remaining in the alloy structure is decreased. Therefore, it is desirable that the tempering temperature does not exceed 270 ° C. Therefore, performing the tempering treatment after the carburizing / quenching treatment in the range of 200 ° C. to 270 ° C. is the tempering condition of the material used for the power roller bearing of the toroidal type continuously variable transmission of the present invention. Further, if possible, carbonitriding that can delay the decomposition of γ R may be performed instead of carburizing.
[0016]
In addition, the alloying element contained in the steel used for the material of the bearing outer ring has the effect of delaying the decomposition of residual austenite, such as silicon Si and molybdenum Mo, and has the property of improving the high temperature strength of the steel. It is desirable that However, when alloying elements such as silicon Si and molybdenum Mo are mixed in steel materials, a sufficient delay effect cannot be exhibited with a mixing ratio of 0.5% or less, while a ratio of 1.5% or more is not achieved. Even if it mixes, the obstacle which arises in terms of the workability of a material and the heat processing characteristic will become large, and manufacturing cost and processing cost will rise. Therefore, mixing silicon Si and molybdenum Mo in the range of 0.5% to 1.5% is an alloy condition of the material used for the power roller bearing of the toroidal type continuously variable transmission of the present invention.
[0017]
The table shown in FIG. 2 shows the material No. obtained by changing the mixing ratio of silicon Si and molybdenum Mo and the tempering temperature. 1-Material No. Fourteen bearing materials are listed. Among these, material No. 1-Material No. 8 is an example of an alloy used as a material for a power roller and a bearing outer ring constituting an embodiment of a power roller bearing of the toroidal-type continuously variable transmission of the present invention, and the mixing ratio of each alloy element and carburizing / quenching treatment The tempering temperature in the subsequent tempering process satisfies the above alloy conditions and tempering conditions of the present invention.
[0018]
Material No. 1 and material no. 2 is an example in which the mixing ratio of silicon Si is changed. 1 is 0.53% close to the lower limit of the alloy conditions of the present invention. No. 2 contains 1.42% silicon Si, which is close to the upper limit value of the alloy conditions of the present invention. Material No. 3 and material no. 4 is an example in which the mixing ratio of molybdenum Mo is changed. 3 is 0.55%, which is close to the lower limit of the alloy conditions of the present invention. No. 4 contains 1.46% molybdenum Mo, which is close to the upper limit of the alloy conditions of the present invention. These material Nos. 1-Material No. In No. 4, the tempering process of 210 degreeC which satisfy | fills the tempering conditions of this invention is performed.
[0019]
Material No. 5-Material No. 7 is an example in which the tempering temperature after carburizing / quenching treatment was changed. 5 is 210 ° C., which is close to the lower limit of the tempering conditions of the present invention. No. 6 is an intermediate value of tempering conditions of the present invention, 240 ° C., material No. In No. 7, a tempering treatment at 270 ° C. close to the upper limit value of the tempering conditions of the present invention is performed. These material Nos. 5-Material No. 7, 0.98% of silicon Si and molybdenum Mo, both of which satisfy the alloy conditions of the present invention, are mixed.
[0020]
Material No. 8 is an example in which a carbonitriding process is performed instead of a carburizing process. Both 0.98% of silicon Si and molybdenum Mo satisfying the alloy condition of the present invention are mixed, and 210 satisfies the tempering condition of the present invention. Tempering at ℃ has been applied.
[0021]
On the other hand, the material No. 9-Material No. 14 is the above-mentioned material No. 1-Material No. 8 is an example of an alloy used as a material for a power roller and a bearing outer ring constituting a comparative example for comparison with the embodiment of the present invention according to No. 8, and the mixing ratio and tempering temperature of each alloy element are the alloy conditions and tempering of the present invention. The condition is not satisfied.
[0022]
Material No. 9 and material no. No. 10 is an example in which the mixing ratio of silicon Si and molybdenum Mo does not satisfy the alloy conditions of the present invention. No. 9, 0.42% silicon Si, which is lower than the lower limit value of the alloy conditions of the present invention, is material No. No. 10 contains 0.45% of molybdenum Mo, which is lower than the lower limit value of the alloy conditions of the present invention. These material Nos. 9 and material no. No. 10 is tempered at 210 ° C., which satisfies the tempering conditions of the present invention.
[0023]
Material No. 11 and material no. No. 12 is an example in which the tempering temperature after carburizing / quenching treatment does not satisfy the tempering conditions of the present invention. No. 11 is 180 ° C. lower than the lower limit of the tempering conditions of the present invention, and the material No. No. 12 is subjected to a tempering treatment at 280 ° C., which is higher than the upper limit value of the tempering conditions of the present invention. These material Nos. 11 and material no. No. 12, 0.98% of silicon Si and molybdenum Mo, both of which satisfy the alloy conditions of the present invention, are mixed.
[0024]
Material No. 13 is an example in which a submerged (uncentered) process is performed instead of the carburizing and quenching process, both 0.85% silicon Si and 0.95% molybdenum Mo satisfying the alloy conditions of the present invention. And tempering at 240 ° C. satisfying the tempering condition of the present invention.
[0025]
Material No. 14 is a normal carburized steel (chromium molybdenum steel: SCM435), which is mixed with 0.25% silicon Si and 0.15% molybdenum Mo, both lower than the alloy conditions of the present invention, and tempered according to the present invention. A tempering treatment at 210 ° C. that satisfies the conditions is performed.
[0026]
3 shows the material No. described in the table of FIG. 1-Material No. 14 is a table summarizing the results of endurance tests conducted on the power roller bearings of bearing symbol A to bearing symbol P, where 14 is the material of the power roller and the bearing outer ring. In addition, the degree of vibration generated when rotating for a certain time with a low load is described.
[0027]
The power roller bearings of bearing symbol A to bearing symbol J have material No. 1-Material No. 8 is an example of the power roller bearing according to the present invention. Among these, in the power roller bearings of bearing symbol A to bearing symbol H, the material No. 14 bearing inner rings (power rollers) made of normal carburized steel are combined, and only the bearing outer rings satisfy the alloy conditions and tempering conditions of the present invention. For the power roller bearings of bearing symbol I and bearing symbol J, the material No. 5 and material no. A bearing inner ring (power roller) made of the alloy of No. 8 is combined, and both the bearing outer ring and the bearing inner ring (power roller) satisfy the alloy condition and tempering condition of the present invention.
[0028]
On the other hand, the power roller bearings of the bearing symbol K to the bearing symbol P have material Nos. 9-Material No. No. 14 bearing outer ring made of the material, and material No. 14 is a comparative example based on a conventional configuration, which includes a bearing inner ring (power roller) made of 14 normal carburized steel. Among these, in the power roller bearings of bearing symbol K to bearing symbol O, each bearing outer ring does not satisfy one of the alloy conditions and tempering conditions of the present invention, and each bearing inner ring (power roller) is an alloy of the present invention. Both conditions and tempering conditions are not met. In the power roller bearing of the bearing symbol P, the material of the bearing outer ring and the bearing inner ring (power roller) are both the material No. No. 14 normal carburized steel, both of which do not satisfy the alloy conditions and tempering conditions of the present invention. The power roller bearing of this bearing symbol P is equivalent to a conventional carburized steel bearing.
[0029]
In the power roller bearings of the bearing symbol A to the bearing symbol J corresponding to the embodiment of the present invention, a life value in the range of 24.0 to 72.1 is obtained. It is within the allowable range. Moreover, in the power roller bearings of bearing symbol A to bearing symbol H in which only the bearing outer ring satisfies the alloy condition and tempering condition of the present invention, the bearing inner ring (power roller) was damaged earlier than the bearing outer ring. The bearing outer ring and the inner bearing ring (power roller) both satisfy the alloying conditions and the tempering conditions of the present invention. In both the bearing symbol I and the bearing symbol J, the outer roller ring precedes the inner bearing ring (power roller). Damaged.
[0030]
On the other hand, among the power roller bearings of bearing symbol K to bearing symbol P corresponding to the comparative example based on the conventional configuration, vibrations generated at low load rotation are allowed except for the power roller bearing of bearing symbol M. Although it is within the range, only a lifetime value in the range of 5.5 to 8.4 is obtained. On the other hand, in the power roller bearing of the bearing symbol M, a life value of 30.1 exceeding the part of the power roller bearing corresponding to the embodiment of the present invention was obtained, but the vibration generated by the low load rotation has an allowable range. It has been exceeded. Further, in the power roller bearings of these bearing symbols K to P, the bearing outer ring was damaged earlier than the bearing inner ring (power roller).
[0031]
As a result, medium carbon or high carbon carburized steel is used as a material for the power roller and the bearing outer ring, and an alloy material having a large amount of residual austenite and delaying decomposition of the residual austenite is within a range that satisfies the alloy condition of the present invention. It can be confirmed that the use of the steel material contained at least as the material of the outer ring is effective in extending the life of the power roller bearing. Moreover, the life extension effect of the power roller bearing of the toroidal type continuously variable transmission of the present invention is mixed with silicon Si or molybdenum Mo at a ratio close to the upper limit value of the alloy conditions of the present invention with respect to the steel material. It can be seen that the maximum is obtained when carbonitriding is performed instead of carburizing and tempering at a temperature close to the lower limit of the tempering conditions of the present invention is performed.
[0032]
Furthermore, an outer ring made of a steel material that satisfies the alloy conditions and tempering conditions of the present invention is combined with a bearing inner ring (power roller) made of a steel material that satisfies the alloy conditions and tempering conditions of the present invention. In this case, compared with a combination with a normal carburized steel bearing inner ring (power roller), the life value is extended by about 50%, and instead of carburizing treatment, steel material that has been subjected to carbonitriding is used as material for the bearing outer ring. In this case, it can be seen that an effect of extending the life of about 50% is recognized. For this reason, in order to have the most excellent life extension effect, a steel material that satisfies the alloy conditions and tempering conditions of the present invention is also used as a material for the bearing inner ring (power roller), and the steel material is carburized. It is desirable to use a power roller bearing such as bearing symbol J that has been subjected to carbonitriding instead of.
[0033]
FIG. 4 shows vibration acceleration values measured for the power roller bearings of the bearing symbol B, the bearing symbol M, and the bearing symbol I among the above-described durability test results by numerical values and graphs. The power roller bearing of bearing symbol B includes a bearing outer ring that satisfies the alloy conditions and tempering conditions of the present invention, and a normal carburized steel bearing inner ring (power roller) that does not satisfy the alloy conditions and tempering conditions of the present invention. In this example, a lifetime value of 39.1 and a vibration acceleration value of 2.8G are obtained. The power roller bearing of bearing symbol M is an example of a combination of a bearing outer ring that does not satisfy the tempering condition of the present invention and a bearing inner ring (power roller) made of ordinary carburized steel, and has a life value of 30.1 and 7. A 3G vibration acceleration value is obtained. The power roller bearing of bearing symbol I is an example of a combination of a bearing outer ring and a bearing inner ring (power roller) both satisfying the alloy conditions and tempering conditions of the present invention, and has a life value of 50.2 and a vibration of 3.5 G. The acceleration value is obtained.
[0034]
FIG. 4 shows that when a steel material that has been tempered at a temperature lower than the lower limit value of the tempering condition of the present invention is used as the material of the bearing outer ring, a vibration acceleration value exceeding the allowable range is generated in the power roller. Has been shown to do. The vibration of the power roller not only hinders smooth shifting operation of the toroidal type continuously variable transmission, but also causes a decrease in durability and reliability of the toroidal type transmission mechanism and the entire toroidal type continuously variable transmission. Therefore, it is extremely important for the operation of the toroidal type continuously variable transmission to be stabilized to raise the tempering temperature in the tempering process to be higher than the lower limit value of the tempering conditions of the present invention.
[0035]
【The invention's effect】
According to the power roller bearing of the toroidal type continuously variable transmission of the present invention, the amount of retained austenite in the steel material that is the material is increased, and the effect of delaying the increased decomposition of austenite is increased, thereby causing a significant temperature change. Since it has high heat resistance and strength in the environment, the life of the power roller bearing is improved. As a result, the durability and reliability of the entire toroidal continuously variable transmission can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a power roller bearing of a toroidal-type continuously variable transmission.
FIG. 2 is a table listing bearing materials obtained by changing the mixing ratio of silicon Si and molybdenum Mo and the tempering temperature.
FIG. 3 is a table summarizing the results of durability tests conducted on power roller bearings using the steel materials shown in the table of FIG. 2 as materials for the power roller and the bearing outer ring.
4 is an explanatory view showing the results of an endurance test performed on a part of the power roller bearing of FIG. 3; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power roller 1a Power roller back surface 2 Bearing outer ring 2a Bearing outer ring opposing surface 3 Rolling element 4 Track groove 5 Cage 6 Pocket hole

Claims (1)

トルク入力軸に取着された互いに対向する入力ディスク及び出力ディスクに当接して駆動力を伝達するパワーローラと前記トルク入力軸に対して捩じれの位置関係にある枢軸によってケーシングと揺動自在に結合したトラニオンが支持する軸受外輪との間に挟持される複数個の転動体と、厚さ方向に貫通する複数個のポケット孔内に前記複数個の転動体を保持して前記複数個の転動体が軌道溝から脱落することを防止する保持器とを備えており、前記パワーローラ及び前記軸受外輪上にそれぞれ形成された円環形状の軌道溝内を転動する前記複数個の転動体によって、前記パワーローラと前記トラニオンとを回転自在に結合すると共に、前記パワーローラに加わるスラスト荷重を受け止めるトロイダル型無段変速機のパワーローラ軸受において、
前記パワーローラ及び前記軸受外輪の材料は、低炭素鋼または中炭素鋼の含有量で炭素を含有し、浸炭又は浸炭窒化処理と焼入処理が施された後に、210℃以上270℃以下で焼戻し処理が施された浸炭鋼であり、かつ、
少なくとも前記軸受外輪の材料は、残留オーステナイトの分解を遅延させる合金元素であるSiを0.53重量%以上1.42重量%以下、およびMoを0.55重量%以上1.46重量%以下含むことを特徴とするトロイダル型無段変速機のパワーローラ軸受。
A power roller that is attached to the torque input shaft and that is in contact with the opposing input disk and output disk to transmit driving force, and a pivot shaft that is twisted with respect to the torque input shaft, is swingably coupled to the casing. A plurality of rolling elements that are sandwiched between bearing outer rings supported by the trunnion and a plurality of rolling elements that hold the plurality of rolling elements in a plurality of pocket holes that penetrate in the thickness direction. Is provided with a cage that prevents the rolling groove from falling off from the raceway groove, and the plurality of rolling elements that roll in the annular raceway groove respectively formed on the power roller and the bearing outer ring, A power roller bearing of a toroidal continuously variable transmission that rotatably couples the power roller and the trunnion and receives a thrust load applied to the power roller. ,
The material of the power roller and the bearing outer ring contains carbon with a content of low carbon steel or medium carbon steel, and after tempering at 210 ° C. or higher and 270 ° C. or lower after being subjected to carburizing or carbonitriding treatment and quenching treatment. Processed carburized steel , and
At least the material of the bearing outer ring contains 0.53% by weight or more and 1.42% by weight or less of Si, which is an alloy element that delays the decomposition of retained austenite , and Mo by 0.55% by weight or more and 1.46% by weight or less. A power roller bearing for a toroidal type continuously variable transmission.
JP34643397A 1997-12-16 1997-12-16 Power roller bearing for toroidal-type continuously variable transmission Expired - Fee Related JP4241951B2 (en)

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JP34643397A JP4241951B2 (en) 1997-12-16 1997-12-16 Power roller bearing for toroidal-type continuously variable transmission

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JP4241951B2 true JP4241951B2 (en) 2009-03-18

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JP4701522B2 (en) * 2001-03-21 2011-06-15 株式会社ジェイテクト Toroidal continuously variable transmission

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