JP3902391B2

JP3902391B2 - Drive wheel bearing device

Info

Publication number: JP3902391B2
Application number: JP2000309538A
Authority: JP
Inventors: 博幸小倉; 晃鳥居; 孝康田窪
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2000-10-10
Filing date: 2000-10-10
Publication date: 2007-04-04
Anticipated expiration: 2020-10-10
Also published as: JP2002114006A

Description

【０００１】
【発明の属する技術分野】
本発明は駆動車輪用軸受装置に関し、詳しくは、自動車の駆動車輪を車体に回転自在に支持する駆動車輪用軸受装置に関する。
【０００２】
【従来の技術】
自動車の駆動車輪用軸受装置には、その用途に応じて種々の形式のものが提案されている。例えば、図３は重量の嵩む自動車用として好適な駆動車輪用軸受装置で、内方部材であるハブ輪１および内輪２、複列の転動体（円すいころ）３，４、外方部材である外輪５、等速自在継手６を主要な構成要素としている。
【０００３】
前記ハブ輪１は、その外周面にアウトボード側の軌道面７が形成されると共に、車輪（図示せず）を取り付けるための車輪取付フランジ９を備えている。この車輪取付フランジ９の円周方向等間隔に、ホイールディスクを固定するためのハブボルト１０が植設されている。このハブ輪１のインボード側端部の外周面に形成された小径段部１１に内輪２を嵌合させ、この内輪２の外周面にインボード側の軌道面８が形成されている。
【０００４】
内輪２は、クリープを防ぐために適当な締め代をもって圧入されている。ハブ輪１の外周面に形成されたアウトボード側の軌道面７と、内輪２の外周面に形成されたインボード側の軌道面８とで複列の軌道面を構成する。この内輪２をハブ輪１の小径段部１１に圧入し、ハブ輪１のインボード側軸方向から挿入される等速自在継手６の継手外輪２１をハブ輪１に締着することにより、その継手外輪２１の肩部２８により内輪２の抜け止めと予圧の付与を行っている。
【０００５】
外輪５は、内周面に前記ハブ輪１および内輪２の軌道面７，８と対向する軌道面１２，１３が形成され、車体（図示せず）に取り付けるための車体取付フランジ１４を備えている。この車体取付フランジ１４は、車体の懸架装置（図示せず）から延びるナックルにボルトで固定されている。
【０００６】
軸受部１５は、複列の円すいころ軸受構造で、ハブ輪１および内輪２の外周面に形成された軌道面７，８と外輪５の内周面に形成された軌道面１２，１３との間に転動体（円すいころ）３，４を介在させ、各列の転動体３，４を保持器１６，１７により円周方向等間隔に支持した構造を有する。
【０００７】
軸受部１５の両端開口部には、外輪５とハブ輪１および内輪２との環状空間を密封する一対のシール１８，１９が外輪５の端部内径に嵌合され、内部に充填されたグリースの漏洩ならびに外部からの水や異物の侵入を防止するようになっている。
【０００８】
等速自在継手６は、ドライブシャフト３９の一端に設けられ、内周面にトラック溝２０が形成された継手外輪２１と、その継手外輪２１のトラック溝２０と対向するトラック溝４０が外周面に形成された継手内輪４１と、前記継手外輪２１のトラック溝２０と継手内輪４１のトラック溝４０との間に組み込まれたボール４２と、継手外輪２１と継手内輪４１間に介在してボール４２を支持する保持器４３とからなる。
【０００９】
前記継手外輪２１は、継手内輪４１、ボール４２および保持器４３を収容したマウス部２２と、そのマウス部２２から軸方向に一体的に延び、外周面にセレーション部２４が形成された軸部２３を有する。この軸部２３をハブ輪１の貫通孔に挿入し、前記軸部２３の外周面および貫通孔の内周面に形成されたセレーション部２４，２５により両者を嵌合させ、その軸端に形成された雄ねじ部２６にナット２７を締め付けることによって、等速自在継手６をハブ輪１に固定している。
【００１０】
従来の駆動車輪用軸受装置には、ハブ輪１の小径段部１１、つまり、インボード側端部と継手外輪２１の軸部根元部位２９との間にパイロット部３０を設けているものがある。このパイロット部３０は、ハブ輪１の小径段部１１の内径をセレーション部２５よりも拡径させることにより形成されている。このようにパイロット部３０を形成してそのパイロット部すきまＡを設けることにより、等速自在継手６の組み付け時、継手外輪２１の軸部２３とハブ輪１とを芯合わせし、その軸部２３をハブ輪１の貫通孔に挿入しやすくしている。なお、前記パイロット部すきまＡとは、ハブ輪１の小径段部１１の端部内径と継手外輪２１の軸部根元部位２９の外径との差を意味する。
【００１１】
【発明が解決しようとする課題】
ところで、転動体３，４に円すいころを使用した図３の駆動車輪用軸受装置では、転動体にボールを使用した構造の駆動車輪用軸受装置に対して接触角が小さい。ここで、前記接触角とは、軸受中心軸に垂直な平面（ラジアル平面）に対して、軌道面７，８によって転動体３，４へ伝達される力の作用方向がなす角度を意味する。
【００１２】
一般的に、転動体にボールを使用した駆動車輪用軸受装置では、接触角が３５°程度であるため、内輪２の接触角方向に作用する荷重は、図３で言えば、継手外輪２１の肩部２８と内輪２との突き合わせ面方向に向いている。
【００１３】
これに対して、転動体３，４に円すいころを使用した駆動車輪用軸受装置では、一般に高負荷容量を得るために接触角が１６〜１８°程度と小さく設定していることから、接触角方向に作用する荷重は、ハブ輪１の小径段部１１と継手外輪２１の軸部根元部位２９との間のパイロット部３０の方向に向かう。
【００１４】
従って、前述したようにパイロット部すきまＡが大きいと、組み付け性は向上するが、接触角方向の荷重によりハブ輪１の小径段部１１および内輪２の軌道面８の変形量が大きくなる。つまり、内輪２の軌道面８の変形量が大きくなると、転動寿命の低下、軌道面８での温度上昇、内輪２と継手外輪２１の肩部２８間でのフレッティングによる軸力（予圧）抜けが発生し易くなる。
【００１５】
また、ハブ輪１の小径段部１１の変形量が大きくなると、ハブ輪１の割損、ハブ輪１と内輪２間でのフレッティングが発生し易くなる。このようにハブ輪１の小径段部１１および内輪２の軌道面８が変形し易くなると、軸受内部が歪んで軸受装置の寿命低下を招来する可能性がある。
【００１６】
そこで、本発明は前記問題点に鑑みて提案されたもので、その目的とするところは、接触角方向の荷重によるハブ輪および内輪の変形がもたらす軸受内部の歪みを抑制して寿命向上を図り得る駆動車輪用軸受装置を提供することにある。
【００１７】
【課題を解決するための手段】
前記目的を達成するための技術的手段として、請求項１に係る発明は、複列の軌道面を内周面に形成した外方部材と、その外方部材の軌道面と対向する軌道面を外周面に形成し、車輪取付フランジを外周面に有する内方部材と、前記外方部材と内方部材のそれぞれの軌道面間に介装された複列の円すいころと、前記内方部材の端面に突き合わせ状態に衝合された肩部を有し、前記内方部材にトルク伝達可能に内嵌する軸部を設けた継手外輪を備えた等速自在継手とからなり、車体に対して車輪を回転自在に支持する駆動車輪用軸受装置において、前記内方部材は、車輪取付フランジと一方の軌道面および小径段部を外周面に形成したハブ輪と、前記小径段部に嵌合し、他方の軌道面を外周面に形成した別体の内輪とからなり、前記継手外輪の軸部根元部位の外径と前記ハブ輪の小径段部の端部内径との間に設けられたすきまであり、かつ、接触角方向の荷重が作用する方向に位置するパイロット部の半径方向すきまを０．４ｍｍ以下とし、前記継手外輪の肩部と突き合わされた前記内輪の端部内径と前記継手外輪の軸部根元部位の外径との間に設けられたすきまからなり、接触角方向の荷重が作用する方向に位置するパイロット部を形成し、前記継手外輪の軸部根元部位の外径とハブ輪の小径段部内径および内輪の端部内径との間に形成された二つのパイロット部のうち、内輪とで形成されるパイロット部の半径方向すきまを、ハブ輪とで形成されるパイロット部の半径方向すきまよりも小さく設定したことを特徴とする（請求項１）。
【００１８】
この請求項１に記載した発明では、前記内方部材は、車輪取付フランジと一方の軌道面および小径段部を外周面に形成したハブ輪と、前記小径段部に嵌合し、他方の軌道面を外周面に形成した別体の内輪とからなり、前記継手外輪の軸部根元部位の外径と前記ハブ輪の小径段部の端部内径との間に設けられたすきであり、かつ、接触角方向の荷重が作用する方向に位置するパイロット部の半径方向すきまを０．４ｍｍ以下とし、前記継手外輪の肩部と突き合わされた前記内輪の端部内径と前記継手外輪の軸部根元部位の外径との間に設けられたすきまからなり、接触角方向の荷重が作用する方向に位置するパイロット部を形成し、前記継手外輪の軸部根元部位の外径とハブ輪の小径段部内径および内輪の端部内径との間に形成された二つのパイロット部のうち、内輪とで形成されるパイロット部の半径方向すきまを、ハブ輪とで形成されるパイロット部の半径方向すきまよりも小さく設定したことにより、接触角方向の荷重によりハブ輪の小径段部および内輪の軌道面の変形を抑制することができ、軸受装置の寿命向上を図ることが実現容易となる。
【００１９】
本発明は、その内周面に複列の軌道面を、かつ、外周面に車体取付フランジをそれぞれ一体に有する外方部材を具備した構造の駆動車輪用軸受装置に適用可能である（請求項２）。
【００２４】
前記車輪取付フランジの基部から内方部材の端部に及ぶ領域に表面硬化層を形成し、この表面硬化層を内方部材の端面近傍で止めた構造とすることが望ましい（請求項３）。このようにすれば、内方部材の軌道面を含む表面硬度を上げることにより、転動疲労寿命の向上、フレッティング低減が図れる。
【００２５】
【発明の実施の形態】
本発明に係る駆動車輪用軸受装置の実施形態を以下に詳述する。なお、図３と同一部分には同一参照符号を付す。
【００２６】
図１に示す実施形態の駆動車輪用軸受装置は、例えば、内方部材であるハブ輪１および内輪２、複列の転動体（円すいころ）３，４、外方部材である外輪５、等速自在継手６を主要な構成要素とする。
【００２７】
前記ハブ輪１は、その外周面に一方の軌道面、つまり、アウトボード側の軌道面７が形成されると共に、車輪（図示せず）を取り付けるための車輪取付フランジ９を備えている。この車輪取付フランジ９の円周方向等間隔に、ホイールディスクを固定するためのハブボルト１０が植設されている。このハブ輪１のインボード側端部の外周面に形成された小径段部１１に内輪２を嵌合させ、この内輪２の外周面に他方の軌道面、つまり、インボード側の軌道面８が形成されている。
【００２８】
内輪２は、クリープを防ぐために適当な締め代をもって圧入されている。ハブ輪１の外周面に形成されたアウトボード側の軌道面７と、内輪２の外周面に形成されたインボード側の軌道面８とで複列の軌道面を構成する。この内輪２をハブ輪１の小径段部１１に圧入し、ハブ輪１のインボード側軸方向から挿入される等速自在継手６の継手外輪２１をハブ輪１に締着することにより、その継手外輪２１の肩部２８により内輪２の抜け止めと予圧の付与を行っている。
【００２９】
外輪５は、内周面に前記ハブ輪１および内輪２の軌道面７，８と対向する軌道面１２，１３が形成され、車体（図示せず）に取り付けるための車体取付フランジ１４を備えている。この車体取付フランジ１４は、車体の懸架装置（図示せず）から延びるナックルにボルトで固定されている。
【００３０】
軸受部１５は、複列の円すいころ軸受構造で、ハブ輪１および内輪２の外周面に形成された軌道面７，８と外輪５の内周面に形成された軌道面１２，１３との間に転動体（円すいころ）３，４を介在させ、各列の転動体３，４を保持器１６，１７により円周方向等間隔に支持した構造を有する。
【００３１】
軸受部１５の両端開口部には、外輪５とハブ輪１および内輪２との環状空間を密封する一対のシール１８，１９が外輪５の端部内径に嵌合され、内部に充填されたグリースの漏洩ならびに外部からの水や異物の侵入を防止するようになっている。
【００３２】
等速自在継手６は、ドライブシャフト３９の一端に設けられ、内周面にトラック溝２０が形成された継手外輪２１と、その継手外輪２１のトラック溝２０と対向するトラック溝４０が外周面に形成された継手内輪４１と、前記継手外輪２１のトラック溝２０と継手内輪４１のトラック溝４０との間に組み込まれたボール４２と、継手外輪２１と継手内輪４１間に介在してボール４２を支持する保持器４３とからなる。
【００３３】
前記継手外輪２１は、継手内輪４１、ボール４２および保持器４３を収容したマウス部２２と、そのマウス部２２から軸方向に一体的に延び、外周面にセレーション部２４が形成された軸部２３を有する。この軸部２３をハブ輪１の貫通孔に挿入し、前記軸部２３の外周面および貫通孔の内周面に形成されたセレーション部２４，２５により両者を嵌合させ、その軸端に形成された雄ねじ部２６にナット２７を締め付けることによって、等速自在継手６をハブ輪１に固定している。なお、セレーション部２４，２５と称するものには、セレーション以外のスプラインも含むものとする。
【００３４】
転動体３，４に円すいころを使用した実施形態の駆動車輪用軸受装置では、接触角が１６〜１８°程度と小さいことから、接触角方向に作用する荷重は、ハブ輪１の小径段部１１および継手外輪２１の軸部根元部位２９の方向に向かう。そこで、この実施形態では、継手外輪２１の軸部根元部位３１とハブ輪１の端部である小径段部１１との間にパイロット部３２を設ける。
【００３５】
このパイロット部３２は、ハブ輪１の小径段部１１の内径をセレーション部２５よりも拡径させ、かつ、継手外輪２１の軸部根元部位３１の外径をセレーション部２４よりも拡径させることにより形成されている。このようにパイロット部３２を形成してそのパイロット部すきまａを０．４ｍｍ以下とする。ここで、前記パイロット部すきまａとは、ハブ輪１の小径段部１１の端部内径と継手外輪２１の軸部根元部位３１の外径との差を意味する。
【００３６】
このようにパイロット部３２を設け、そのパイロット部すきまａを０．４ｍｍ以下としたことにより、接触角方向の荷重によりハブ輪１の小径段部１１の変形を抑制することができ、ハブ輪１の割損防止、ハブ輪１と内輪２間のフレッティング低減が図れ、軸受装置の寿命を向上させることができる。前記パイロット部すきまａが０．４ｍｍより大きいと、ハブ輪１の小径段部１１の変形を抑制する所期の効果が得られない。
【００３７】
また、図２は本発明の他の実施形態を示し、この実施形態の駆動車輪用軸受装置は、前述したパイロット部３２を、継手外輪２１の軸部根元部位３１とハブ輪１の小径段部１１との間に形成すると共に、継手外輪２１の肩部２８と突き合わされた内輪２の端部と継手外輪２１の軸部根元部位３１との間にもパイロット部３３を形成する。なお、後者のパイロット部３３は、継手外輪２１の軸部根元部位３１を、ハブ輪１の小径段部１１の端面と継手外輪２１の肩部２８との間隙まで延在するように拡径させることにより形成される。
【００３８】
このように内輪２の端部と継手外輪２１の軸部根元部位３１との間にパイロット部３３を形成したことにより、接触角方向の荷重により内輪２の軌道面８の変形を抑制することができ、転動寿命の向上、温度上昇の抑制、内輪２と継手外輪２１の肩部２８間でのフレッティング低減による軸力（予圧）抜け防止が図れ、軸受装置の寿命を向上させることができる。
【００３９】
ここで、継手外輪２１の軸部根元部位３１とハブ輪１および内輪２の端部との間に形成された二つのパイロット部３２，３３のうち、内輪１とで形成されるパイロット部すきまｂを、ハブ輪１とで形成されるパイロット部すきまａよりも小さく設定する。
【００４０】
つまり、前述したようにハブ輪１の小径段部１１と継手外輪２１の軸部根元部位３１との間に形成されたパイロット部すきまａを０．４ｍｍ以下とするのに対して、継手外輪２１の軸部根元部位３１と内輪２の端部との間に形成するパイロット部すきまｂを０．０５ｍｍ以下とする。このパイロット部すきまｂが０．０５ｍｍより大きいと、内輪２の軌道面８の変形を抑制する所期の効果が得られない。二つのパイロット部３３，３２のうち、一方のパイロット部３３により、内輪２の変形を抑制し、さらに大きな荷重が作用すると、他方のパイロット部３２により、ハブ輪１の変形を抑制する。
【００４１】
また、前述した実施形態において、車輪取付フランジ９の基部からハブ輪１の小径段部１１に及ぶ領域に表面硬化層３４を形成し、この表面硬化層３４をハブ輪１の小径段部１１の端面近傍で止めた構造とする。車輪取付フランジ９の基部は、外輪５のアウトボード側端部に装着されたシール１８のシールリップが摺接するハブ輪１の外周面、つまり、シールランド部であり、そのシールランド部から軌道面７を経て小径段部１１に及ぶ領域に表面硬化層３４を形成する。
【００４２】
この表面硬化層３４の各部、シールランド部ではシール１８のシールリップが摺接するため、耐摩耗性が要求され、軌道面７では転動体３が転動するため、耐寿命性が要求され、小径段部１１では内輪２と嵌合するため、耐クリープ性、耐フレッティング性が要求される。
【００４３】
前記表面硬化層３４を形成するための熱処理は、高周波焼き入れが適している。表面硬化処理としての高周波熱処理は、誘導加熱の特色を有効に生かして表面硬化層３４を自由に選定し、耐摩耗性を与えたり疲れ強さを改善することができる。誘導加熱は、電磁誘導現象を利用して金属内で電気エネルギーを直接熱エネルギーに変えて発熱させる方法で、これを利用した高周波熱処理には多くの特徴がある。特に、局部加熱ができ、硬化層深さの選定が自由であり、また硬化層以外には著しく熱影響を与えないように制御できるので、母材の性能を保持できる。
【００４４】
【実施例】
例えば、パイロット部すきまの寸法違いによる旋回寿命試験を実施したところ、以下のとおりの試験結果が得られた。ハブ輪１の小径段部１１と継手外輪２１の軸部根元部位３１との間に０．４ｍｍのパイロット部すきまａを形成し、かつ、内輪２の端部と継手外輪２１の軸部根元部位３１との間に０．０５ｍｍのパイロット部すきまｂを形成した実施例（図２参照）では、運転時間：１６５時間、温度上昇：５０℃以下の寿命試験結果が得られた。
【００４５】
これに対して、ハブ輪１の小径段部１１と継手外輪２１の軸部根元部位２９との間に２ｍｍのパイロット部すきまＡを形成し、かつ、内輪２の端部と継手外輪２１の軸部根元部位２９との間に８．７５ｍｍのパイロット部すきまＢを形成した比較例（図３参照）では、運転時間：５２時間、温度上昇：７２〜９０℃の寿命試験結果しか得られなかった。
【００４６】
この試験結果から、実施例の駆動車輪用軸受装置における運転時間が比較例のものの３倍以上となり、温度上昇も抑制されることから、軸受装置の寿命向上が容易であることが明らかである。
【００４７】
【発明の効果】
本発明によれば、前記内方部材は、車輪取付フランジと一方の軌道面および小径段部を外周面に形成したハブ輪と、前記小径段部に嵌合し、他方の軌道面を外周面に形成した別体の内輪とからなり、前記継手外輪の軸部根元部位の外径と前記ハブ輪の小径段部の端部内径との間に設けられたすきまであり、かつ、接触角方向の荷重が作用する方向に位置するパイロット部の半径方向すきまを０．４ｍｍ以下とし、前記継手外輪の肩部と突き合わされた前記内輪の端部内径と前記継手外輪の軸部根元部位の外径との間に設けられたすきまからなり、接触角方向の荷重が作用する方向に位置するパイロット部を形成し、前記継手外輪の軸部根元部位の外径とハブ輪の小径段部内径および内輪の端部内径との間に形成された二つのパイロット部のうち、内輪とで形成されるパイロット部の半径方向すきまを、ハブ輪とで形成されるパイロット部の半径方向すきまよりも小さく設定したことにより、接触角方向の荷重によりハブ輪の小径段部および内輪の軌道面の変形を抑制することができ、ハブ輪および内輪の割損防止、ハブ輪および内輪のフレッティング低減が図れ、軸受装置の寿命向上を図ることができて長寿命で高品質の駆動車輪用軸受装置を提供できる。
【図面の簡単な説明】
【図１】本発明に係る実施形態を説明するもので、駆動車輪用軸受装置の構造例を示す断面図である。
【図２】本発明に係る他の実施形態の駆動車輪用軸受装置の構造例を示す断面図である。
【図３】従来の駆動車輪用軸受装置の構造例を示す断面図である。
【符号の説明】
１内方部材（ハブ輪）
２内方部材（内輪）
３，４転動体（円すいころ）
５外方部材（外輪）
７，８軌道面
９車輪取付フランジ
１２，１３軌道面
２１継手外輪
２３軸部
２８肩部
３１軸部根元部位
３２，３３パイロット部
ａ，ｂパイロット部すきま[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive wheel bearing device, and more particularly, to a drive wheel bearing device that rotatably supports a drive wheel of an automobile on a vehicle body.
[0002]
[Prior art]
Various types of bearing devices for driving wheels of automobiles have been proposed depending on the application. For example, FIG. 3 shows a bearing device for a driving wheel that is suitable for a heavy automobile. The hub wheel 1 and the inner ring 2 are inner members, double row rolling elements (cone rollers) 3 and 4, and outer members. The outer ring 5 and the constant velocity universal joint 6 are the main components.
[0003]
The hub wheel 1 has a raceway surface 7 on the outboard side formed on the outer peripheral surface thereof, and includes a wheel mounting flange 9 for mounting a wheel (not shown). Hub bolts 10 for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the wheel mounting flange 9. The inner ring 2 is fitted to a small diameter step portion 11 formed on the outer peripheral surface of the inboard side end portion of the hub wheel 1, and the inboard side raceway surface 8 is formed on the outer peripheral surface of the inner ring 2.
[0004]
The inner ring 2 is press-fitted with an appropriate tightening margin to prevent creep. The outboard side raceway surface 7 formed on the outer peripheral surface of the hub wheel 1 and the inboard side raceway surface 8 formed on the outer peripheral surface of the inner ring 2 constitute a double row raceway surface. The inner ring 2 is press-fitted into the small-diameter step portion 11 of the hub wheel 1, and the joint outer ring 21 of the constant velocity universal joint 6 inserted from the inboard side axial direction of the hub wheel 1 is fastened to the hub wheel 1. The shoulder 28 of the joint outer ring 21 prevents the inner ring 2 from coming off and gives a preload.
[0005]
The outer ring 5 is formed with raceway surfaces 12 and 13 facing the raceway surfaces 7 and 8 of the hub wheel 1 and the inner ring 2 on the inner peripheral surface, and includes a vehicle body attachment flange 14 for attachment to a vehicle body (not shown). Yes. The vehicle body mounting flange 14 is fixed to a knuckle extending from a vehicle suspension system (not shown) with bolts.
[0006]
The bearing portion 15 has a double-row tapered roller bearing structure, and includes raceway surfaces 7 and 8 formed on the outer peripheral surfaces of the hub wheel 1 and the inner ring 2 and raceway surfaces 12 and 13 formed on the inner peripheral surface of the outer ring 5. The rolling elements (cone rollers) 3 and 4 are interposed therebetween, and the rolling elements 3 and 4 in each row are supported by the cages 16 and 17 at equal intervals in the circumferential direction.
[0007]
A pair of seals 18 and 19 for sealing the annular space between the outer ring 5 and the hub ring 1 and the inner ring 2 are fitted to the inner diameter of the end of the outer ring 5 at both ends of the bearing portion 15, and the grease filled inside This prevents leakage of water and intrusion of water and foreign matter from the outside.
[0008]
The constant velocity universal joint 6 is provided at one end of a drive shaft 39, a joint outer ring 21 having a track groove 20 formed on the inner peripheral surface, and a track groove 40 facing the track groove 20 of the joint outer ring 21 on the outer peripheral surface. The formed joint inner ring 41, the ball 42 incorporated between the track groove 20 of the joint outer ring 21 and the track groove 40 of the joint inner ring 41, and the ball 42 interposed between the joint outer ring 21 and the joint inner ring 41. It comprises a retainer 43 to be supported.
[0009]
The joint outer ring 21 includes a mouth portion 22 that houses a joint inner ring 41, a ball 42, and a cage 43, and a shaft portion 23 that extends integrally from the mouth portion 22 in the axial direction and has a serration portion 24 formed on the outer peripheral surface thereof. Have The shaft portion 23 is inserted into the through hole of the hub wheel 1, and both are fitted by serration portions 24 and 25 formed on the outer peripheral surface of the shaft portion 23 and the inner peripheral surface of the through hole. The constant velocity universal joint 6 is fixed to the hub wheel 1 by tightening a nut 27 to the male thread portion 26 formed.
[0010]
Some conventional drive wheel bearing devices are provided with a pilot portion 30 between the small diameter step portion 11 of the hub wheel 1, that is, between the inboard side end portion and the shaft root portion 29 of the joint outer ring 21. . The pilot portion 30 is formed by expanding the inner diameter of the small diameter step portion 11 of the hub wheel 1 more than the serration portion 25. By forming the pilot portion 30 and providing the pilot portion clearance A in this way, the shaft portion 23 of the joint outer ring 21 and the hub wheel 1 are aligned when the constant velocity universal joint 6 is assembled. Is easily inserted into the through hole of the hub wheel 1. The pilot portion clearance A means a difference between the inner diameter of the end portion of the small diameter step portion 11 of the hub wheel 1 and the outer diameter of the shaft root portion 29 of the joint outer ring 21.
[0011]
[Problems to be solved by the invention]
Incidentally, in the drive wheel bearing device of FIG. 3 using tapered rollers for the rolling elements 3 and 4, the contact angle is smaller than that of the drive wheel bearing device having a structure using balls as the rolling elements. Here, the contact angle means an angle formed by an action direction of a force transmitted to the rolling elements 3 and 4 by the raceway surfaces 7 and 8 with respect to a plane (radial plane) perpendicular to the bearing central axis.
[0012]
Generally, in a drive wheel bearing device using a ball as a rolling element, the contact angle is about 35 °. Therefore, the load acting in the contact angle direction of the inner ring 2 is, as shown in FIG. It faces in the direction of the butting surface between the shoulder 28 and the inner ring 2.
[0013]
On the other hand, in a drive wheel bearing device using tapered rollers for the rolling elements 3 and 4, the contact angle is generally set as small as about 16 to 18 ° in order to obtain a high load capacity. The load acting in the direction is directed toward the pilot portion 30 between the small diameter step portion 11 of the hub wheel 1 and the shaft root portion 29 of the joint outer ring 21.
[0014]
Therefore, as described above, when the pilot portion clearance A is large, the assemblability is improved, but the deformation amount of the small-diameter step portion 11 of the hub wheel 1 and the raceway surface 8 of the inner ring 2 increases due to the load in the contact angle direction. That is, when the amount of deformation of the raceway surface 8 of the inner ring 2 increases, the rolling life decreases, the temperature rises on the raceway surface 8, and the axial force (preload) due to fretting between the inner ring 2 and the shoulder 28 of the joint outer ring 21. Missing is likely to occur.
[0015]
Further, when the deformation amount of the small-diameter step portion 11 of the hub wheel 1 is increased, the hub wheel 1 is easily broken and fretting between the hub wheel 1 and the inner ring 2 is likely to occur. If the small-diameter step portion 11 of the hub wheel 1 and the raceway surface 8 of the inner ring 2 are easily deformed in this way, the inside of the bearing may be distorted and the life of the bearing device may be reduced.
[0016]
Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to improve the service life by suppressing the distortion in the bearing caused by the deformation of the hub ring and the inner ring due to the load in the contact angle direction. The object is to provide a bearing device for a drive wheel.
[0017]
[Means for Solving the Problems]
As technical means for achieving the above object, the invention according to claim 1 includes an outer member having a double-row raceway surface formed on an inner peripheral surface, and a raceway surface facing the raceway surface of the outer member. An inner member formed on the outer peripheral surface and having a wheel mounting flange on the outer peripheral surface, a double row tapered roller interposed between the raceway surfaces of the outer member and the inner member, and the inner member A constant velocity universal joint having a joint outer ring having a shoulder portion abutted against the end face and having a shaft portion fitted into the inner member so as to be able to transmit torque; In the drive wheel bearing device that rotatably supports the inner member , the inner member is fitted to a wheel mounting flange, a hub wheel having one raceway surface and a small-diameter step portion formed on an outer peripheral surface, and the small-diameter step portion. It consists an inner ring of another body formed on the outer peripheral surface of the other track surface, of the joint outer ring Wherein the outer diameter of the parts root portion is a clearance provided between the end portion inner diameter of the cylindrical portion of the hub wheel, and the radial clearance of the pilot portion which the load of the contact angle direction is located in the direction acting 0 4 mm or less, and a clearance provided between the inner diameter of the end of the inner ring abutted against the shoulder of the outer ring of the joint and the outer diameter of the shaft base of the outer ring of the joint. A pilot portion located in the acting direction, and formed of two pilot portions formed between the outer diameter of the shaft root portion of the joint outer ring, the inner diameter of the small diameter step portion of the hub ring, and the inner diameter of the end of the inner ring. The radial clearance of the pilot portion formed by the inner ring is set to be smaller than the radial clearance of the pilot portion formed by the hub ring (Claim 1).
[0018]
In the first aspect of the invention, the inner member includes a wheel mounting flange, a hub wheel having one raceway surface and a small-diameter step portion formed on the outer peripheral surface, and the other raceway. consists an inner ring of the separate formation of the surface on the outer peripheral surface, a plow provided between the end portion inner diameter of the cylindrical portion of the outer diameter and the hub wheel of the shaft portion root portion of the joint outer ring, and, The radial clearance of the pilot part located in the direction in which the load in the contact angle direction acts is 0.4 mm or less, the inner diameter of the end of the inner ring abutted against the shoulder of the joint outer ring, and the base part of the shaft part of the joint outer ring A pilot portion located in the direction in which the load in the contact angle direction acts, and the outer diameter of the base portion of the shaft portion of the joint outer ring and the small-diameter step portion of the hub ring. Two parts formed between the inner diameter and the inner diameter of the end of the inner ring. Of lot portion, the radial clearance of the pilot section formed by the inner ring, by setting smaller than the radial clearance of the pilot section formed by the hub wheel, the load of the contact angle direction of the hub Deformation of the raceway surface of the small-diameter stepped portion and the inner ring can be suppressed, and it becomes easy to realize improvement in the life of the bearing device.
[0019]
INDUSTRIAL APPLICABILITY The present invention is applicable to a bearing device for a drive wheel having a structure including an outer member integrally having a double row raceway surface on its inner peripheral surface and a vehicle body mounting flange on its outer peripheral surface. 2).
[0024]
The wheel to form a surface hardened layer from the base of the mounting flange in a region spanning the end of the inner member, it is desirable to stop the structure of the surface hardened layer near the end face of the inner member (claim 3). In this way, by increasing the surface hardness including the raceway surface of the inner member, it is possible to improve the rolling fatigue life and reduce fretting.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a drive wheel bearing device according to the present invention will be described in detail below. The same parts as those in FIG. 3 are denoted by the same reference numerals.
[0026]
The drive wheel bearing device of the embodiment shown in FIG. 1 includes, for example, a hub wheel 1 and an inner ring 2 that are inner members, double-row rolling elements (cone rollers) 3 and 4, an outer ring 5 that is an outer member, and the like. The quick universal joint 6 is a main component.
[0027]
The hub wheel 1 has one raceway surface, that is, an outboard raceway surface 7 formed on the outer peripheral surface thereof, and a wheel mounting flange 9 for mounting a wheel (not shown). Hub bolts 10 for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the wheel mounting flange 9. The inner ring 2 is fitted to a small diameter step portion 11 formed on the outer peripheral surface of the inboard side end portion of the hub wheel 1, and the other raceway surface, that is, the inboard side raceway surface 8 is fitted to the outer peripheral surface of the inner ring 2. Is formed.
[0028]
The inner ring 2 is press-fitted with an appropriate tightening margin to prevent creep. The outboard side raceway surface 7 formed on the outer peripheral surface of the hub wheel 1 and the inboard side raceway surface 8 formed on the outer peripheral surface of the inner ring 2 constitute a double row raceway surface. The inner ring 2 is press-fitted into the small-diameter step portion 11 of the hub wheel 1, and the joint outer ring 21 of the constant velocity universal joint 6 inserted from the inboard side axial direction of the hub wheel 1 is fastened to the hub wheel 1. The shoulder 28 of the joint outer ring 21 prevents the inner ring 2 from coming off and gives a preload.
[0029]
The outer ring 5 is formed with raceway surfaces 12 and 13 facing the raceway surfaces 7 and 8 of the hub wheel 1 and the inner ring 2 on the inner peripheral surface, and includes a vehicle body attachment flange 14 for attachment to a vehicle body (not shown). Yes. The vehicle body mounting flange 14 is fixed to a knuckle extending from a vehicle suspension system (not shown) with bolts.
[0030]
The bearing portion 15 has a double-row tapered roller bearing structure, and includes raceway surfaces 7 and 8 formed on the outer peripheral surfaces of the hub wheel 1 and the inner ring 2 and raceway surfaces 12 and 13 formed on the inner peripheral surface of the outer ring 5. The rolling elements (cone rollers) 3 and 4 are interposed therebetween, and the rolling elements 3 and 4 in each row are supported by the cages 16 and 17 at equal intervals in the circumferential direction.
[0031]
A pair of seals 18 and 19 for sealing the annular space between the outer ring 5 and the hub ring 1 and the inner ring 2 are fitted to the inner diameter of the end of the outer ring 5 at both ends of the bearing portion 15, and the grease filled inside This prevents leakage of water and intrusion of water and foreign matter from the outside.
[0032]
The constant velocity universal joint 6 is provided at one end of a drive shaft 39, a joint outer ring 21 having a track groove 20 formed on the inner peripheral surface, and a track groove 40 facing the track groove 20 of the joint outer ring 21 on the outer peripheral surface. The formed joint inner ring 41, the ball 42 incorporated between the track groove 20 of the joint outer ring 21 and the track groove 40 of the joint inner ring 41, and the ball 42 interposed between the joint outer ring 21 and the joint inner ring 41. It comprises a retainer 43 to be supported.
[0033]
The joint outer ring 21 includes a mouth portion 22 that houses a joint inner ring 41, a ball 42, and a cage 43, and a shaft portion 23 that extends integrally from the mouth portion 22 in the axial direction and has a serration portion 24 formed on the outer peripheral surface thereof. Have The shaft portion 23 is inserted into the through hole of the hub wheel 1, and both are fitted by serration portions 24 and 25 formed on the outer peripheral surface of the shaft portion 23 and the inner peripheral surface of the through hole. The constant velocity universal joint 6 is fixed to the hub wheel 1 by tightening a nut 27 to the male thread portion 26 formed. In addition, what is called serration parts 24 and 25 shall also include splines other than serrations.
[0034]
In the drive wheel bearing device according to the embodiment in which tapered rollers are used for the rolling elements 3 and 4, the contact angle is as small as about 16 to 18 °. Therefore, the load acting in the contact angle direction is a small diameter step portion of the hub wheel 1. 11 and the shaft root portion 29 of the joint outer ring 21. Therefore, in this embodiment, the pilot portion 32 is provided between the shaft root portion 31 of the joint outer ring 21 and the small diameter step portion 11 that is the end portion of the hub wheel 1.
[0035]
The pilot portion 32 increases the inner diameter of the small-diameter step portion 11 of the hub wheel 1 more than the serration portion 25 and increases the outer diameter of the shaft base portion 31 of the joint outer ring 21 more than the serration portion 24. It is formed by. Thus, the pilot part 32 is formed and the pilot part clearance a is set to 0.4 mm or less. Here, the pilot portion clearance a means the difference between the end inner diameter of the small diameter step portion 11 of the hub wheel 1 and the outer diameter of the shaft root portion 31 of the joint outer ring 21.
[0036]
Thus, by providing the pilot portion 32 and setting the pilot portion clearance a to 0.4 mm or less, deformation of the small-diameter step portion 11 of the hub wheel 1 can be suppressed by the load in the contact angle direction. Can be prevented, fretting between the hub ring 1 and the inner ring 2 can be reduced, and the life of the bearing device can be improved. If the pilot portion clearance a is larger than 0.4 mm, the desired effect of suppressing the deformation of the small diameter step portion 11 of the hub wheel 1 cannot be obtained.
[0037]
FIG. 2 shows another embodiment of the present invention. In the drive wheel bearing device of this embodiment, the pilot portion 32 described above is connected to the shaft root portion 31 of the joint outer ring 21 and the small diameter step portion of the hub wheel 1. 11, and a pilot portion 33 is also formed between the end portion of the inner ring 2 butted against the shoulder portion 28 of the joint outer ring 21 and the shaft base portion 31 of the joint outer ring 21. The latter pilot portion 33 expands the diameter of the shaft base portion 31 of the joint outer ring 21 so as to extend to the gap between the end surface of the small diameter step portion 11 of the hub wheel 1 and the shoulder portion 28 of the joint outer ring 21. Is formed.
[0038]
By thus forming the pilot portion 33 between the end portion of the inner ring 2 and the shaft root portion 31 of the joint outer ring 21, it is possible to suppress deformation of the raceway surface 8 of the inner ring 2 due to a load in the contact angle direction. It is possible to improve the rolling life, suppress the temperature rise, prevent the axial force (preload) from coming off by reducing fretting between the inner ring 2 and the shoulder portion 28 of the joint outer ring 21, and improve the life of the bearing device. .
[0039]
Here, of the two pilot portions 32 and 33 formed between the shaft root portion 31 of the joint outer ring 21 and the ends of the hub wheel 1 and the inner ring 2, the pilot portion clearance b formed with the inner ring 1. Is set smaller than the pilot portion clearance a formed by the hub wheel 1.
[0040]
That is, as described above, the pilot portion clearance a formed between the small-diameter step portion 11 of the hub wheel 1 and the shaft root portion 31 of the joint outer ring 21 is 0.4 mm or less, whereas the joint outer ring 21. The pilot portion clearance b formed between the shaft base portion 31 and the end of the inner ring 2 is set to 0.05 mm or less. If the pilot portion clearance b is larger than 0.05 mm, the desired effect of suppressing deformation of the raceway surface 8 of the inner ring 2 cannot be obtained. Of the two pilot parts 33, 32, one pilot part 33 suppresses deformation of the inner ring 2, and when a larger load is applied, the other pilot part 32 suppresses deformation of the hub wheel 1.
[0041]
Further, in the above-described embodiment, the surface hardened layer 34 is formed in a region extending from the base portion of the wheel mounting flange 9 to the small diameter step portion 11 of the hub wheel 1, and this surface hardened layer 34 is formed on the small diameter step portion 11 of the hub wheel 1. The structure is fixed near the end face. The base portion of the wheel mounting flange 9 is the outer peripheral surface of the hub wheel 1 slidably in contact with the seal lip of the seal 18 attached to the end portion on the outboard side of the outer ring 5, that is, the seal land portion. 7, a hardened surface layer 34 is formed in a region extending to the small diameter step portion 11.
[0042]
Since the seal lip of the seal 18 is in sliding contact with each part of the surface hardened layer 34 and the seal land portion, wear resistance is required, and the rolling element 3 rolls on the raceway surface 7, so that life resistance is required, and a small diameter is required. Since the step portion 11 is fitted to the inner ring 2, creep resistance and fretting resistance are required.
[0043]
As the heat treatment for forming the surface hardened layer 34, induction hardening is suitable. In the high-frequency heat treatment as the surface hardening treatment, the surface hardening layer 34 can be freely selected by effectively utilizing the feature of induction heating, and wear resistance and fatigue strength can be improved. Induction heating is a method of generating heat by directly converting electrical energy into thermal energy in a metal using an electromagnetic induction phenomenon, and there are many features of high-frequency heat treatment using this. In particular, local heating can be performed, the depth of the hardened layer can be freely selected, and control other than the hardened layer can be controlled so as not to significantly affect the heat, so that the performance of the base material can be maintained.
[0044]
【Example】
For example, the following test results were obtained when a swivel life test with a difference in the dimensions of the pilot section clearance was performed. A pilot portion clearance a of 0.4 mm is formed between the small-diameter step portion 11 of the hub wheel 1 and the shaft base portion 31 of the joint outer ring 21, and the end portion of the inner ring 2 and the shaft base portion of the joint outer ring 21 are formed. In the example (refer to FIG. 2) in which a pilot portion clearance b of 0.05 mm was formed between the first and second members 31, a life test result of an operation time of 165 hours and a temperature increase of 50 ° C. or less was obtained.
[0045]
On the other hand, a pilot portion clearance A of 2 mm is formed between the small-diameter step portion 11 of the hub wheel 1 and the shaft root portion 29 of the joint outer ring 21, and the end of the inner ring 2 and the shaft of the joint outer ring 21 are formed. In the comparative example (see FIG. 3) in which the pilot portion clearance B of 8.75 mm was formed between the root portion 29 and the root portion 29, only a life test result of operation time: 52 hours and temperature increase: 72 to 90 ° C. was obtained. .
[0046]
From this test result, it is clear that the operating time of the bearing device for a driving wheel of the embodiment is three times or more that of the comparative example and the temperature rise is suppressed, so that it is easy to improve the life of the bearing device.
[0047]
【The invention's effect】
According to the present invention, the inner member is fitted to the wheel mounting flange, one of the raceway surface and a small-diameter step portion on the outer peripheral surface, and the small-diameter step portion, and the other raceway surface to the outer peripheral surface. to consist the inner ring of another body formed, the a gap is provided between the outer diameter of the shaft portion root portion of the joint outer ring and the end portion inner diameter of the cylindrical portion of the hub wheel, and the contact angle direction The radial clearance of the pilot portion located in the direction in which the load acts is 0.4 mm or less, the inner diameter of the end of the inner ring abutted against the shoulder of the joint outer ring, and the outer diameter of the root portion of the shaft of the joint outer ring Forming a pilot portion positioned in the direction in which the load in the contact angle direction acts, and forming the outer diameter of the shaft root portion of the joint outer ring, the inner diameter of the small diameter step portion of the hub ring, and the inner ring Two pilot parts formed between the inner diameter of the end parts The radial clearance of the pilot section formed by the inner ring, by setting smaller than the radial clearance of the pilot section formed by the hub wheel, the cylindrical portion of the hub wheel by the load of the contact angle direction and The deformation of the raceway surface of the inner ring can be suppressed, the breakage of the hub ring and the inner ring can be prevented, the fretting of the hub ring and the inner ring can be reduced, the life of the bearing device can be improved, and a long life and high quality can be achieved. A drive wheel bearing device can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of the structure of a drive wheel bearing device, illustrating an embodiment according to the present invention.
FIG. 2 is a cross-sectional view showing a structural example of a bearing device for a drive wheel according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a structural example of a conventional drive wheel bearing device.
[Explanation of symbols]
1 Inner member (hub ring)
2 Inner member (inner ring)
3, 4 Rolling elements (cone rollers)
5 Outer member (outer ring)
7, 8 Raceway surface 9 Wheel mounting flange 12, 13 Raceway surface 21 Joint outer ring 23 Shaft portion 28 Shoulder portion 31 Shaft base portion 32, 33 Pilot portion a, b Pilot portion clearance

Claims

An outer member 5 having double-row raceway surfaces 12 and 13 formed on the inner peripheral surface, and raceway surfaces 7 and 8 facing the raceway surfaces 12 and 13 of the outer member 5 are formed on the outer peripheral surface, and wheel mounting flanges are formed. Inner members 1 and 2 having an outer peripheral surface 9 , double-row tapered rollers 3 and 4 interposed between the raceway surfaces of the outer member 5 and the inner members 1 and 2 , A constant velocity provided with a joint outer ring 21 having a shoulder portion 28 abutted against the end surfaces of the members 1 and 2 and having a shaft portion 23 fitted into the inner members 1 and 2 so as to be able to transmit torque. In a drive wheel bearing device consisting of a universal joint and rotatably supporting the wheel with respect to the vehicle body,
The inner members 1 and 2 are fitted to the wheel ring 1 and the hub wheel 1 having one raceway surface 7 and a small diameter step portion 11 formed on the outer peripheral surface, and the small diameter step portion 11, and the other raceway surface 8. the consists separate the inner ring 2 which formed on the outer peripheral surface, to plow provided between the end portion inner diameter of the outer diameter and the hub wheel 1 of the cylindrical portion 11 of the shaft portion base portion 31 of the joint outer ring 21 And the radial clearance a of the pilot portion 32 located in the direction in which the load in the contact angle direction acts is 0.4 mm or less, and the inner diameter of the end portion of the inner ring 2 that is abutted against the shoulder portion 28 of the joint outer ring 21 And the outer diameter of the shaft base portion 31 of the joint outer ring 21, and a pilot portion 33 is formed which is positioned in the direction in which the load in the contact angle direction acts, and the shaft of the joint outer ring 21 The outer diameter of the root portion 31 and the inner diameter of the small diameter step portion of the hub wheel 1 Of the pilot portion 33 formed between the inner ring 2 and the pilot ring formed between the inner ring 2 and the inner ring 2. A bearing device for a drive wheel, wherein the bearing device is set to be smaller than the radial clearance a of the portion 32 .

2. The wheel bearing device according to claim 1, wherein the outer member 5 integrally has double-row raceway surfaces 12 and 13 on an inner peripheral surface thereof and a vehicle body mounting flange 14 on an outer peripheral surface thereof. .

Wherein the surface hardened layer 34 in a region from the base up to the end of the inner member 2 of the wheel mounting flange 9 is formed, stopped this surface hardened layer 34 in the vicinity of the end faces of the inner members 1 and 2 The bearing device for a drive wheel according to claim 1 or 2 .