JP3880786B2

JP3880786B2 - Drive wheel bearing device

Info

Publication number: JP3880786B2
Application number: JP2000243175A
Authority: JP
Inventors: 弘二佐橋; 和彦穂積; 啓助曽根; 仁博小澤; 晃鳥居
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2000-04-12
Filing date: 2000-08-10
Publication date: 2007-02-14
Anticipated expiration: 2020-08-10
Also published as: JP2001354004A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車の駆動車輪を車体に対して回転自在に支持する車輪軸受装置に関するもので、より詳しくは、ハブ輪と等速自在継手の外側継手部材と複列の軸受とをユニット化し、複列のインナーレースの少なくとも一方を外側継手部材に形成した駆動車輪用軸受装置に関する。
【０００２】
【従来の技術】
ＦＲ車の後輪、ＦＦ車の前輪、４ＷＤ車の全輪といった自動車の駆動車輪は、駆動車輪用軸受装置により懸架装置に支持される。従来の駆動車輪用軸受装置としては、例えば特開平11-62951号に示すものがある。
【０００３】
図１２に示すように、この軸受装置は、ハブ輪１０と軸受２０と等速自在継手３０とをユニット化した構造で、複列のインナーレースのうちの一方１２をハブ輪１０に形成し、他方４２を等速自在継手３０の外側継手部材４０に形成したものである。ハブ輪１０と外側継手部材４０とは、ハブ輪１０の内周面に形成された雌スプライン５３と外側継手部材４０の外周面に形成された雄スプライン５５とを係合させ、さらにハブ輪１０から突出した外側継手部材４０の軸端を加締めることによって結合されている。また、この軸受装置では、曲げ剛性等を高めるため、外側継手部材４０の雄スプライン５５の両側に円筒面７７、７９を形成し、この円筒面７７、７９をハブ輪１０側の雌スプライン５３の歯先面に嵌合させてある。
【０００４】
【発明が解決しようとする課題】
図１２に示す構造では、円筒面と雌スプライン５３の歯先面とをがたつきなく嵌合させる必要がある。そのため、円筒面や歯先面には、同軸度をはじめとして高い精度が要求され、これを実現すべく、外側継手部材やハブ輪、スプラインの加工精度をかなり高める必要があり、コストアップが懸念される。
【０００５】
そこで、本発明は、大幅なコストアップを抑えつつ、ハブ輪と外側継手部材との間の結合強度を増大させることを目的とする。
【０００６】
【課題を解決するための手段】
上記目的の達成のため、本発明は、ハブ輪、等速自在継手、および複列の軸受とをユニット化し、軸受の複列のインナーレースのうち、少なくともアウトボード側のインナーレースをハブ輪に形成した駆動車輪用軸受装置において、ハブ輪と外側継手部材とのうち、何れか一方を他方の外周にセレーションを介して嵌合させ、内周側の部材に雄セレーションを形成すると共に、外周側の部材に雄セレーションと嵌合し、かつ歯先面の径が一定の雌セレーションを形成し、内周側の部材の雄セレーションよりも軸端側を雄セレーションの溝径よりも小径に形成すると共に、その軸端に被加締め部を形成し、内周側の部材の被加締め部と雄セレーションとの間を雌セレーションと対向させ、雄セレーションの軸端側の溝底端部を外周側部材の端面よりも前記軸端側と反対の側に配置し、内周側部材の被加締め部を加締めて内周側の部材と外周側の部材とを結合し、加締め部の近傍で雌セレーションを当該加締めに伴う塑性変形で充足したことを特徴とするものである。
【０００７】
この駆動車輪用軸受装置は、トルク伝達手段の軸方向一方側に上記加締め部を、他方側にハブ輪と外側継手部材とをがたつきなく嵌合させた嵌合部を有するものとするのがよい。この嵌合部ではハブ輪と外側継手部材とががたつかないよう密着嵌合しているので、嵌合部はラジアル荷重の受け部として機能する。
【０００８】
トルク伝達手段としては、例えばセレーションが考えられる。ここでの「セレーション」には、スプラインも含まれる。
【０００９】
外側継手部材ハブ輪との加締めによる結合は、例えば外側継手部材の外周にハブ輪を嵌合する場合には、外側継手部材の軸端を加締めてハブ輪に係合させ、ハブ輪の外周に外側継手部材を嵌合する場合には、ハブ輪の端部を加締めて外側継手部材に係合させることによって行うことができる。
【００１０】
加締め部となるステム部の軸端は加締めを行う部分であるために延性が必要である。従って、加締め部は、熱処理前の素材の硬さと同程度の硬さにしておくのがよい。
【００１２】
この場合、外側継手部材に設けられたセレーションの軸端側を切り抜け構造としておくのが望ましい。この切り抜け構造において、外側継手部材に設けられたセレーションの軸端側の溝底端部を、ハブ輪の端面よりもインボード側に配置しておけば、せん断荷重の集中を回避することができ、加締め割れの発生が防止可能となる。
【００１３】
外側継手部材およびハブ輪のセレーション嵌合部のうち、少なくとも軸端と反対側を、締め代をもって嵌合させておくのが望ましい。上記のように加締め部の近傍でセレーション等のトルク伝達手段を塑性変形で充足した場合、この充足部で外側継手部材とハブ輪とが互いに食い込んでガタのない状態になっているため、充足部でのトルク分担が大きくなる。これに対し、外側継手部材の軸端と反対側で両セレーションを締め代をもって嵌合させておけば、この締まり嵌め部分でもトルクが分担され、充足部でのトルク分担が低減されるため、加締め部の割れ等を回避することができる。
【００１４】
この場合、セレーション嵌合部のうちの軸端側をすきま嵌めとすることにより、セレーション同士を嵌合させる際の作業性が改善される。
【００１５】
締め代を確保するための手段としては、外側継手部材およびハブ輪のうちの何れか一方のセレーションを軸方向に対して傾斜させるもの、あるいは外側継手部材およびハブ輪のうちの何れか一方のセレーションを、軸端と反対側を軸方向に対して傾斜させると共に、これよりも軸端側を軸方向に沿ってこれと平行に形成するもの等が考えられる。
【００１６】
トルク伝達手段は、ハブ輪と外側継手部材との嵌合面に凹凸部を介在させ、この嵌合面を、凹凸部を含めて少なくとも部分的に拡径または縮径させて加締めることにより形成することもできる。この場合、凹凸部が相手部材の嵌合面に食い込むため、ハブ輪と外側継手部材との間でトルク伝達を行うことが可能となり、また、ハブ輪と外側継手部材の結合強度を確保し、加締め部の緩みを長期間防止することが可能となる。凹凸部は、ハブ輪側あるいは外側継手部材側の何れか一方または双方に設けることができる。
【００１７】
凹凸部に熱処理による硬化処理を施しておけば、凹凸部が潰れにくくなって相手側の嵌合面にしっかりと食い込むため、より強固な塑性結合が実現できる。
【００１８】
【発明の実施の形態】
以下、本発明の実施形態を図１〜図１１に基づいて説明する。
【００１９】
図１に示す駆動車輪用軸受装置は、ハブ輪１０と、軸受装置２０と、等速自在継手３０とを主要な構成要素としている。ここで、車両に組み付けた状態で車両の外側寄りとなる側をアウトボード側といい、上記各図（図１１を除く）では左側がアウトボード側となる。一方、車両の中央寄りとなる側をインボード側といい、各図では右側がインボード側となる。
【００２０】
ハブ輪１０は、アウトボード側の端部に駆動車輪（図示せず）を取り付けるためのフランジ１４を備えており、フランジ１４の円周方向等間隔位置にホイールディスクを固定するためのハブボルト１５が植え込まれる。ハブ輪１０のフランジ１４寄りの外周面にアウトボード側のインナーレース１２を形成してある。ハブ輪１０は軸心部に軸方向の貫通孔１６を有している。
【００２１】
等速自在継手３０は、外周部にトラック溝３１を備えた内側継手部材３２と、内周部にトラック溝４１を備えた外側継手部材４０と、内側継手部材３２のトラック溝３１と外側継手部材４０のトラック溝４１との間に介在する複数のボール３４と、すべてのボールを同一平面内に保持するためのケージ３６とで構成されている。内側継手部材３２は軸方向の貫通孔３３を有し、図示は省略してあるが、エンジン側に配置される等速自在継手と連結された駆動軸とセレーション等で結合するようになっている。外側継手部材４０は、マウス部４３とステム部４５とからなり、ステム部４５にてハブ輪１０の貫通孔１６内周と嵌合している。マウス部４３の肩面４４寄りの外周面にインボート側のインナーレース４２を形成してある（インナーレース４２は、別体で作られたものを外側継手部材４０の外径部に嵌合してもよい）。マウス部４３の肩面４４がハブ輪１０の端面と当接し、これによりハブ輪１０と外側継手部材４０の軸方向の位置決めがなされ、かつ、インナーレース１２、４２間の寸法が規定される。ステム部４５は、椀状のマウス部４３の底と連通した軸方向の貫通孔４６を設けることによって中空にしてあるが中実であってもよい。
【００２２】
軸受２０は、複列の外方部材２１と複列の転動体２９を含む。外方部材２１は車体（図示せず）に取付けるためのフランジ２４を備え、内周面に複列の転動体２９が転動する複列のアウターレース２２を形成してある。ハブ輪１０のインナーレース１２および外側継手部材４０のインナーレース４２と外方部材２１の複列のアウターレース２２との間に複列の転動体２９が組込まれている。複列のアウターレース２２およびインナーレース１２、４２と、両レース間に組込まれた転動体２９と、外方部材２１とで軸受２０が構成される。ここでは転動体２９としてボールを使用した複列アンギュラ玉軸受の場合を図示してあるが、重量の嵩む自動車用の車輪軸受装置の場合には、転動体として円すいころを使用した複列円すいころ軸受を採用する場合もある。
【００２３】
外方部材２１の両端開口部にはシール２６、２８が装着され、軸受内部に充填したグリースや潤滑油の漏洩、並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。また、上述のようにステム部４５の貫通孔４６がマウス部４３の内部空間と連通していることから、マウス部４３内に充填されたグリースの漏出を防止するため、貫通孔４６のマウス部４３側端部にエンドプレート３８を装着してある。このエンドプレート３８にはアルミニウムなどの軽量で熱伝導性のよい材料を採用するのが好ましい。
【００２４】
ハブ輪１０と等速自在継手３０の外側継手部材４０とは、トルク伝達手段５１を介して結合される。トルク伝達手段５１は、外側継手部材４０のステム部４５に設けた凹凸とハブ輪１０に設けた凹凸とを円周方向で係合させることによって両部材１０、４０間のトルク伝達を可能ならしめたもので、例えばセレーションやスプラインで構成することができる（以下の「セレーション」にはスプラインも含むものとする）。図２に拡大して示すように、ハブ輪１０の内周面に形成された雌セレーション５３は、当該内周面の軸方向ほぼ中心部からアウトボード側の端部までの略全域にわたって形成され、外側継手部材４０のステム部４５外周面に形成された雄セレーション５５は、ハブ輪１０側の雌セレーション５３と部分的に嵌合する領域、具体的には雌セレーション５３のインボード側部分とのみ嵌合する領域に形成されている。従って、ハブ輪１０の雌セレーション５３のうちでアウトボード側の部分は、外側継手部材４０の雄セレーション５５とは嵌合しない非嵌合領域となる。ハブ輪１０内周面の雌セレーション５３よりもインボード側、および外側継手部材４０外周面の雄セレーション５５よりもアウトボード側には、それぞれセレーション５３、５５の加工を容易にするための逃げ部５７、５９が形成されている。
【００２５】
トルク伝達手段５１のインボード側には、ハブ輪１０と外側継手部材４０とを半径方向のがたつきを生じることなく嵌合させた嵌合部６１が設けられる。この嵌合部６１では、外側継手部材４０の円筒状外周面とハブ輪１０の円筒状内周面とが締まり嵌めで嵌合されており、これより嵌合部６１ではハブ輪１０に負荷されたラジアル荷重を外側継手部材４０のステム部４５で受けることが可能となる。
【００２６】
さらにハブ輪１０と外側継手部材４０とは加締め部６３によって軸方向に非分離に塑性結合される。図２は外側継手部材４０の軸端を加締めてハブ輪１０に係合させた例で、この場合の加締めは、破線で示すように外側継手部材４０のアウトボード側の軸端に小径円筒状の被加締め部６５を設け、これを例えば揺動加締めにより外径側に塑性変形することによって行われる。揺動加締めは、図１１に示すように、ポンチ６７の中心軸Ｏ₁を車輪軸受装置の中心軸Ｏ₂に対して振れ回せながら（みそすり運動）被加締め部６５を塑性変形させる工程である。
【００２７】
この場合、ポンチ６７が被加締め部６５の内径奥深くに入り込んで、この深部でも外径側へ加圧力を及ぼすため、被加締め部６５の基端側でも外径側への塑性変形が生じ、外側継手部材４０の外周肉部がハブ輪１０側のトルク伝達手段５１（雌セレーション５３）の凹凸をその軸端付近で部分的に充足する（充足部６９を散点模様で表す）。すなわち、当該外周肉部がハブ輪１０内周に形成された凹凸（雌セレーション５３の谷部や歯先面等）のアウトボード側端部付近に食い込んでその表面に隙間なく密着する。そのため、ハブ輪１０と外側継手部材４０との間の円周方向のがたつきが詰められ、車輪軸受装置の剛性が高まって、運転時のフィーリングの向上やトルク伝達手段５１の摩耗回避等を図ることができる。ハブ輪１０と外側継手部材４０との間の嵌合部は、通常品と同程度の精度に仕上げれば足り、図１２に示す従来品のように同軸度等に高い精度が要求されることもないので、製作コストの大幅アップを回避することができる。また、充足部６９ではハブ輪１０と外側継手部材４０とが互いに密着するため、この充足部６９でも上記嵌合部６１と同様にラジアル方向の荷重を受けることが可能となる。従って、嵌合部６１と合わせてトルク伝達手段５１の軸方向両側でラジアル荷重を支持することが可能となり、これより軸受装置全体の曲げ剛性（モーメント負荷能力）が高まる。
【００２８】
なお、以上の説明では、加締め方法として揺動加締めを例示しているが、ハブ輪１０側のトルク伝達手段５１を充足できる限り、他の加締め方法を採用してもよい。
【００２９】
図２に示すように、外側継手部材４０の軸端内周には、軸中央部の内径との関係により、アウトボード側が拡径した段部７１が設けられるが、図１１の揺動加締めの際には、この段部７１よりもアウトボード側の領域を外径側へ塑性変形させる。図２では段部７１をハブ輪１０の端面１０ａ近傍に配置しているが、図３では上記段部７１を図２よりもさらにインボード側に配置し、塑性変形域をインボード側に拡大させている。この場合、加締め後の充足部６９の領域もインボード側に拡大するため、より高いがた詰め効果が得られる。図４は、揺動加締めの後にポンチ７３等の治工具を用い、外側継手部材４０の軸端を拡径し、より強固に充足させた例である。図５は、ハブ輪１０の雌セレーション５３をハブ輪１０の端面１０ａまで到達させずに、これよりもインボード側で打ち切った例である。この場合、充足部６９もインボード側に変位させる必要があるので、図４と同様にポンチ７３等の治工具を用い、外側継手部材４０の軸端を拡径し、強固に充足させている。
【００３０】
ところで、上記のように被加締め部６５を加締める際には、加締め割れ対策が必要となる。加締め割れとは、加締め中、あるいは加締め後の軸受使用中に加締め部６３に割れを生じる現象である。その要因としては、第一に変形歪みの集中が考えられる。すなわち、加締めの際には、雄セレーション５５の軸端部分と平滑な被加締め部６５との間の剛性差からその境界部分にせん段歪みが集中し、この部分が加締めに伴って大きく変形するため、加締め部６３に割れが発生し易くなる。
【００３１】
この対策としては、図６および図７に示すように、例えば、雄セレーション５５の軸端側でステム部４５の外周（本実施形態では被加締め部６５の外周）を雄セレーション５５の溝底５５ａよりも小径に形成すると共に、外側継手部材４０の雄セレーション５５のうち、ステム４５の軸端側（図面左）の端部を切り抜け構造とし、この切り抜け部５２をハブ輪１０の端面１０ａよりもインボード側に配置する構造が考えられる。ここでいう「切り抜け構造」とは、雄セレーション５５の溝底５５ａを軸方向と平行にストレートに切り抜けさせて被加締め部６５の外周領域に開口させた構造を意味する。このように雄セレーション５５の溝底５５ａのうち、軸端側の端部（切り抜け部５２）をハブ輪端面１０ａよりもインボード側に配置することにより、加締め時の変形は平滑円筒状の被加締め部６５で主に生じるので、せん断歪みの集中を緩和して割れの発生を回避することができる。
【００３２】
加締め割れの第二の要因としては、セレーション嵌合部５１の軸端でトルクの分担が過大になることが考えられる。すなわち、通常のセレーション嵌合では雄・雌セレーション部５５、５３が円周方向ですきま嵌めとなるためにガタを生じるが、上記のように加締めによる塑性流動で雌セレーション５３を充足させた場合には、両セレーション５３、５５間の円周方向のすきまが詰められてガタのない状態となるため、この部分でのトルク分担が大きくなるのである。
【００３３】
この対策としては、セレーション嵌合部のうち、軸端の反対側、つまりインボード側で締め代をもって両セレーション５３、５５を嵌合させることが考えられる。これによりセレーション嵌合部のインボード側端部に締まり嵌め部が形成され、この部分でもトルクが分担されるようになるので、充足部６９でのトルク分担を軽減することができ、加締め部６３の割れを回避することが可能となる。
【００３４】
インボード側に締まり嵌め部を形成する方法としては、例えば雄セレーション５５および雌セレーション５３のうちの何れか一方を軸線に対して僅かに傾けることにより、当該セレーションに捩れ角を持たせることが考えられる。この場合、当該セレーションの全長にわたって傾ける他、インボード側部分のみを傾けると共に、アウトボード側で両セレーション５３、５５を軸方向と平行に形成してもよい。
【００３５】
この他、加締め部６３の歪み速度の限界値を考慮し、加締め時の加工速度の限界値を見極めることによっても加締め割れを防止することができる。
【００３６】
ハブ輪１０は、炭素含有量０．４５〜０．８０重量％の炭素鋼等を使用して鍛造加工により成形され、フランジ１４の基端部付近から始まって、シール２６との対向面（シール面）、インナーレース１２、外側継手部材４０の肩面４４との突合せ面にかけての領域には、高周波焼入れ等の熱処理によりＨｖ５１０〜９００程度の硬化層が形成される。このうち、ハブ輪１０の小端部端面（肩面４４との突合せ面）は、当該端面の摩耗による予圧荷重の低下を防止するためにＨＲＣ５０以上、好ましくはＨＲＣ５８以上に硬化される。同様の硬化層（Ｈｖ５１０〜９００）は、ハブ輪１０内周面のうち、嵌合部６１の円筒状内周面、および雌セレーション部５３の領域にも形成される。このうち、嵌合部６１の円筒状内周面は、インナレース１２、４２にボール２９を介して曲げモーメントが負荷された際の嵌合部６１内周面のフレッティングや異音、寿命低下を防止するため、ＨＲＣ５０以上、好ましくはＨＲＣ５８以上に硬化され、雌セレーション部５３は、短いセレーション嵌合長さ（十数ミリ程度）であっても十分なトルク伝達が行え、かつ摩耗、摩減を防止できるよう、ＨＲＣ５０以上まで硬化される。
【００３７】
外側継手部材４０もハブ輪１０と同様に炭素含有量が０．４５〜０．８０重量％の炭素鋼を使用して鍛造加工により成形され、高周波焼入れ等の熱処理が施される。熱処理による硬化層は、シール２８との対向面（シール面）から始まって、インナーレース４２、肩面４４、嵌合部６１（円筒状外周面）、雄セレーション５５にかけての領域にＨｖ５１０〜９００程度となるよう形成される。一方、加締め部６３となるステム部４５の軸端（被加締め部６５）は加締めを行う部分であるために延性が必要であり、従って焼入れ処理を施さず未焼入れ部分として、熱処理前の素材の硬さ（Ｈｖ２００〜３００程度）を保持している。
【００３８】
なお、上記実施形態においては、トルク伝達手段５１や嵌合部１６の軸方向長さを十分に確保できるよう、ハブ輪１０の小径側端面と外側継手部材４０の肩面４４との突合せ部分をボール２９間ピッチの中心線Ｐよりもインボード側に設けるのが望ましい。
【００３９】
図８は、図１に示す駆動車輪用車輪軸受において、外側継手部材４０のステム部４５の軸端（図面左側）に部分的に中実部４７を形成した例である。この中実部４７は、ステム部４５外周の雄セレーション５５を転造等で加工する際の加工性を高めるためのものであり、この目的に対応して雄セレーション５５はその一部または全部（図面では一部）が中実部４７の外周領域に含まれるように形成されている。
【００４０】
図９は、ハブ輪１０と外側継手部材４０との嵌合面に凹凸部７５を介在させ、この嵌合面を、凹凸部７５を含む形で部分的に拡径させて加締めた例である。凹凸部７５は、例えば外側継手部材４０のステム部４５外周面にローレット加工等を施すことによって形成される。嵌合面の拡径加締めは、例えばステム部４５を貫通孔４６の内径よりも大きな外径を備えた加締め治具を貫通孔４６内に圧入し、ステム部４５を内径側から外径側に拡径させることによって行われる。この加締めにより、ステム部４５の凹凸部７５がハブ輪１０の内周面に食い込むので、ハブ輪１０と外側継手部材４０とが塑性結合される。凹凸部７５の食い込みにより、ハブ輪１０とステム部４５との間でトルク伝達が可能となるので、上記凹凸部７５は図１のトルク伝達手段５１としても機能する。
【００４１】
上記拡径加締めが終了した後、図１と同様に、ハブ輪１０の端面１０ａより突出したステム部４５の軸端を揺動加締め等で外径側に加締めてハブ輪端面１０ａに係合させることにより、トルク伝達手段５１としての凹凸部７５がより一層充足されるため、図１と同様に強固な結合力が得られる。
【００４２】
なお、凹凸部７５が介在した嵌合面を拡径させるだけでなく、これを縮径させることによっても、例えばハブ輪１０を外径側から内径側に縮径加締めするなどして嵌合面を縮径させることによっても同様の効果が得られる。上記凹凸部７５では凹凸加工により加工硬化が生じるが、この部分にさらに高周波焼入れ等の熱処理で硬化処理を施せば、凹凸部７５が潰れにくくなって相手側の嵌合面にしっかりと食い込むので、より強固な塑性結合が達成される。
【００４３】
図１０は、ハブ輪１０を外側継手部材４０の内周に嵌合した駆動車輪用軸受装置を示すもので、ハブ輪１０の一端（インボード側）を加締めて外側継手部材４０のマウス部４３底に係合させた例である。この場合も、図１および図６と同様にハブ輪１０と外側継手部材４０との間にトルク伝達手段５１（図７はセレーションの場合を示す）を介在させ、外側継手部材４０の内周に設けられた雌セレーションを、加締め部６３の近傍で加締めにより充足することによって、強固な結合力が得られる。これ以外の構成、および作用は図１および図６に示す実施形態と同じであるので、共通する部材に同じ参照番号を付して重複説明を省略する。
【００４４】
【発明の効果】
このように本発明では、加締め部の近傍でトルク伝達手段を当該加締めに伴う塑性変形で充足しているので、ハブ輪と外側継手部材との間の円周方向のがたつきが詰められる。そのため、ハブ輪と外側継手部材との間の結合強度が向上し、車輪軸受装置の剛性が高まる。また、ハブ輪と外側継手部材との間の嵌合部は、通常品と同程度の精度に仕上げれば足りるので、製作コストが大幅にアップすることもない。
【００４５】
外側継手部材のセレーションの軸端側を切り抜け構造とした状態で、当該セレーションの軸端側の溝底端部を、ハブ輪の端面よりもインボード側に配置しておけば、被加締め部でのせん断荷重の集中を回避することができ、加締め割れの発生が防止可能となってハブ輪と外側継手部材との結合強度を高めることができる。同様の効果は、セレーション嵌合部のうちの少なくとも軸端と反対側を、締め代をもって嵌合させることによっても実現され得る。
【図面の簡単な説明】
【図１】本発明にかかる駆動車輪用軸受装置の断面図である。
【図２】ハブ輪と外側継手部材との嵌合部を拡大した断面図である。
【図３】ハブ輪と外側継手部材との嵌合部を拡大した断面図である。
【図４】ハブ輪と外側継手部材との嵌合部を拡大した断面図である。
【図５】ハブ輪と外側継手部材との嵌合部を拡大した断面図である。
【図６】ハブ輪と外側継手部材との嵌合部を拡大した断面図である。
【図７】雄セレーションの軸端部分を展開した拡大平面図である。
【図８】駆動車輪用軸受装置の他の実施形態を示す断面図である。
【図９】駆動車輪用軸受装置の他の実施形態を示す断面図である。
【図１０】駆動車輪用軸受装置の他の実施形態を示す断面図である。
【図１１】揺動加締め工程を示す断面図である。
【図１２】従来の駆動車輪用軸受装置の一例を示す断面図である。
【符号の説明】
１０ハブ輪
１２インナーレース
２０軸受
３０等速自在継手
４０外側継手部材
４２インナーレース
５１トルク伝達手段
５２切り抜け部
５３雌セレーション
５５雄セレーション
５５ａ溝底
６１嵌合部
６３加締め部
６５被加締め部
７５凹凸部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wheel bearing device that rotatably supports a driving wheel of an automobile with respect to a vehicle body, and more specifically, a hub wheel, an outer joint member of a constant velocity universal joint, and a double row bearing are unitized. The present invention relates to a drive wheel bearing device in which at least one of double row inner races is formed on an outer joint member.
[0002]
[Prior art]
Driving wheels of automobiles such as a rear wheel of an FR vehicle, a front wheel of an FF vehicle, and all wheels of a 4WD vehicle are supported by a suspension device by a driving wheel bearing device. As a conventional drive wheel bearing device, for example, there is one shown in JP-A-11-62951.
[0003]
As shown in FIG. 12, the bearing device has a structure in which the hub wheel 10, the bearing 20, and the constant velocity universal joint 30 are unitized, and one of the double-row inner races is formed on the hub wheel 10. The other 42 is formed on the outer joint member 40 of the constant velocity universal joint 30. The hub wheel 10 and the outer joint member 40 engage a female spline 53 formed on the inner peripheral surface of the hub wheel 10 and a male spline 55 formed on the outer peripheral surface of the outer joint member 40, and further the hub wheel 10. They are coupled by caulking the shaft end of the outer joint member 40 projecting from the outer joint member 40. Further, in this bearing device, cylindrical surfaces 77 and 79 are formed on both sides of the male spline 55 of the outer joint member 40 in order to increase bending rigidity and the like, and the cylindrical surfaces 77 and 79 are formed on the female spline 53 on the hub wheel 10 side. It is fitted to the tooth tip surface.
[0004]
[Problems to be solved by the invention]
In the structure shown in FIG. 12, it is necessary to fit the cylindrical surface and the tooth tip surface of the female spline 53 without rattling. For this reason, high accuracy is required for the cylindrical surface and the tooth tip surface, including coaxiality. To achieve this, it is necessary to significantly increase the processing accuracy of the outer joint member, hub ring, and spline, and there is a concern about cost increase. Is done.
[0005]
Accordingly, an object of the present invention is to increase the coupling strength between the hub wheel and the outer joint member while suppressing a significant cost increase.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention unitizes a hub wheel, a constant velocity universal joint, and a double row bearing, and among the double row inner races of the bearing, at least the inner race on the outboard side is used as the hub ring . In the drive wheel bearing device thus formed , either one of the hub wheel and the outer joint member is fitted to the other outer periphery via serrations, and male serrations are formed on the inner peripheral member, and the outer peripheral side The male serration is fitted into the male member and a female serration with a constant tooth tip surface diameter is formed, and the shaft end side is formed smaller than the male serration groove diameter than the male serration of the inner peripheral side member. At the same time, a caulking portion is formed at the shaft end, the portion between the caulking portion of the inner peripheral side and the male serration is opposed to the female serration, and the groove bottom end portion of the male serration on the axial end side is the outer periphery. End face of side member Place on a side opposite to the remote the shaft end side, by combining the members of the inner circumferential side of the member and the outer peripheral side to be caulked portion of the inner peripheral member caulked, the female serration near the caulked portion Is satisfied by the plastic deformation accompanying the caulking.
[0007]
This bearing device for a drive wheel has a fitting part in which the above-mentioned caulking part is fitted on one side in the axial direction of the torque transmission means, and the hub wheel and the outer joint member are fitted on the other side without rattling. It is good. In this fitting portion, since the hub wheel and the outer joint member are closely fitted so that they do not rattle, the fitting portion functions as a receiving portion for the radial load.
[0008]
As the torque transmission means, for example, serration can be considered. The “serration” here includes splines.
[0009]
For example, when the hub ring is fitted to the outer periphery of the outer joint member, the shaft end of the outer joint member is swaged and engaged with the hub ring. When the outer joint member is fitted to the outer periphery, the end portion of the hub wheel can be crimped and engaged with the outer joint member.
[0010]
Since the shaft end of the stem portion that becomes the crimping portion is a portion that performs crimping, ductility is required. Therefore, it is preferable that the caulking portion has a hardness comparable to that of the material before the heat treatment.
[0012]
In this case, it is desirable that the shaft end side of the serration provided in the outer joint member has a cut-out structure. In this cut-out structure, if the groove bottom end on the shaft end side of the serration provided on the outer joint member is arranged on the inboard side from the end surface of the hub wheel, concentration of shear load can be avoided. The occurrence of caulking cracks can be prevented.
[0013]
Of the serration fitting portions of the outer joint member and the hub wheel, it is desirable that at least the side opposite to the shaft end is fitted with a tightening margin. As described above, when the torque transmission means such as serration is satisfied by plastic deformation in the vicinity of the caulking portion, the outer joint member and the hub wheel bite into each other at this sufficient portion, and there is no backlash. The torque sharing at the part increases. On the other hand, if both serrations are fitted with a tightening margin on the side opposite to the shaft end of the outer joint member, the torque is shared even in this interference fitting portion, and the torque sharing at the sufficient portion is reduced. It is possible to avoid cracking of the fastening portion.
[0014]
In this case, the workability at the time of fitting serrations is improved by making the shaft end side of the serration fitting portions a clearance fit.
[0015]
As means for securing the tightening allowance, the serration of any one of the outer joint member and the hub ring is inclined with respect to the axial direction, or the serration of either the outer joint member or the hub ring. In this case, the side opposite to the shaft end is inclined with respect to the axial direction, and the shaft end side is formed parallel to the axial direction.
[0016]
The torque transmission means is formed by interposing an uneven portion on the fitting surface between the hub wheel and the outer joint member, and caulking the fitting surface by expanding or reducing the diameter at least partially including the uneven portion. You can also In this case, since the concavo-convex portion bites into the mating surface of the mating member, it is possible to transmit torque between the hub wheel and the outer joint member, and ensure the coupling strength between the hub wheel and the outer joint member, It is possible to prevent loosening of the crimped portion for a long period of time. The concavo-convex portion can be provided on either or both of the hub wheel side and the outer joint member side.
[0017]
If the concavo-convex part is subjected to a heat treatment by heat treatment, the concavo-convex part is less likely to be crushed and firmly bites into the mating surface on the other side, so that a stronger plastic bond can be realized.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0019]
The drive wheel bearing device shown in FIG. 1 includes a hub wheel 10, a bearing device 20, and a constant velocity universal joint 30 as main components. Here, the side closer to the outside of the vehicle when assembled to the vehicle is referred to as the outboard side, and the left side is the outboard side in each of the above drawings (excluding FIG. 11). On the other hand, the side closer to the center of the vehicle is called the inboard side, and the right side is the inboard side in each figure.
[0020]
The hub wheel 10 includes a flange 14 for attaching a drive wheel (not shown) to an end portion on the outboard side, and a hub bolt 15 for fixing a wheel disk at a circumferentially equidistant position of the flange 14 is provided. Implanted. An outboard inner race 12 is formed on the outer peripheral surface of the hub wheel 10 near the flange 14. The hub wheel 10 has an axial through hole 16 in the axial center.
[0021]
The constant velocity universal joint 30 includes an inner joint member 32 having a track groove 31 on the outer peripheral portion, an outer joint member 40 having a track groove 41 on the inner peripheral portion, and the track groove 31 and the outer joint member of the inner joint member 32. A plurality of balls 34 interposed between the 40 track grooves 41 and a cage 36 for holding all the balls in the same plane. The inner joint member 32 has an axial through-hole 33, which is not shown, but is connected to a drive shaft connected to a constant velocity universal joint disposed on the engine side by serration or the like. . The outer joint member 40 includes a mouth portion 43 and a stem portion 45, and the stem portion 45 is fitted to the inner periphery of the through hole 16 of the hub wheel 10. An inner race 42 on the inboard side is formed on the outer peripheral surface of the mouse portion 43 near the shoulder surface 44 (the inner race 42 is fitted with an outer diameter portion of the outer joint member 40 which is made separately). May be). The shoulder surface 44 of the mouse portion 43 abuts against the end surface of the hub wheel 10, whereby the hub wheel 10 and the outer joint member 40 are positioned in the axial direction, and the dimension between the inner races 12 and 42 is defined. The stem portion 45 is hollow by providing an axial through hole 46 communicating with the bottom of the bowl-shaped mouse portion 43, but may be solid.
[0022]
The bearing 20 includes a double row outer member 21 and a double row rolling element 29. The outer member 21 includes a flange 24 for attachment to a vehicle body (not shown), and a double row outer race 22 on which a double row rolling element 29 rolls is formed on the inner peripheral surface. Double row rolling elements 29 are incorporated between the inner race 12 of the hub wheel 10, the inner race 42 of the outer joint member 40, and the double row outer race 22 of the outer member 21. The double row outer race 22 and the inner races 12 and 42, the rolling elements 29 incorporated between both races, and the outer member 21 constitute a bearing 20. Here, the case of a double row angular contact ball bearing using a ball as the rolling element 29 is illustrated, but in the case of a heavy wheel bearing device for automobiles, a double row tapered roller using a tapered roller as the rolling element. A bearing may be employed.
[0023]
Seals 26 and 28 are attached to both end openings of the outer member 21 to prevent leakage of grease and lubricating oil filled in the bearing and intrusion of water and foreign matters from the outside. Further, since the through hole 46 of the stem portion 45 communicates with the internal space of the mouse portion 43 as described above, the mouth portion of the through hole 46 is prevented in order to prevent leakage of grease filled in the mouse portion 43. An end plate 38 is attached to the 43 side end. The end plate 38 is preferably made of a light material having good thermal conductivity such as aluminum.
[0024]
The hub wheel 10 and the outer joint member 40 of the constant velocity universal joint 30 are coupled via a torque transmission means 51. The torque transmission means 51 enables torque transmission between the members 10 and 40 by engaging the unevenness provided on the stem portion 45 of the outer joint member 40 and the unevenness provided on the hub wheel 10 in the circumferential direction. For example, it can be composed of serrations and splines (the following “serration” includes splines). As shown in FIG. 2 in an enlarged manner, the female serration 53 formed on the inner peripheral surface of the hub wheel 10 is formed over substantially the entire region from the substantially central portion in the axial direction of the inner peripheral surface to the end portion on the outboard side. The male serration 55 formed on the outer peripheral surface of the stem portion 45 of the outer joint member 40 is a region that partially fits with the female serration 53 on the hub wheel 10 side, specifically, an inboard side portion of the female serration 53. It is formed only in the area where it fits. Accordingly, a portion of the female serration 53 of the hub wheel 10 on the outboard side becomes a non-fitting region where the male serration 55 of the outer joint member 40 is not fitted. Relief portions for facilitating machining of the serrations 53 and 55 on the inboard side of the female serration 53 on the inner peripheral surface of the hub wheel 10 and on the outboard side of the male serration 55 on the outer peripheral surface of the outer joint member 40, respectively. 57 and 59 are formed.
[0025]
On the inboard side of the torque transmission means 51, a fitting portion 61 is provided in which the hub wheel 10 and the outer joint member 40 are fitted without causing radial backlash. In the fitting portion 61, the cylindrical outer peripheral surface of the outer joint member 40 and the cylindrical inner peripheral surface of the hub wheel 10 are fitted with an interference fit, so that the fitting portion 61 is loaded on the hub wheel 10. The radial load can be received by the stem portion 45 of the outer joint member 40.
[0026]
Further, the hub wheel 10 and the outer joint member 40 are non-separably plastically coupled in the axial direction by the caulking portion 63. FIG. 2 shows an example in which the shaft end of the outer joint member 40 is swaged and engaged with the hub wheel 10. In this case, the staking is performed at the shaft end on the outboard side of the outer joint member 40 with a small diameter. A cylindrical caulking portion 65 is provided, and this is performed by plastic deformation of the caulking caulking portion 65 toward the outer diameter side by, for example, swing caulking. As shown in FIG. 11, the swing caulking is a step of plastically deforming the portion to be caulked 65 while swinging the central axis O ₁ of the punch 67 with respect to the central axis O ₂ of the wheel bearing device (shaving motion). It is.
[0027]
In this case, since the punch 67 enters deep inside the crimped portion 65 and applies pressure to the outside diameter side even at this deep portion, plastic deformation to the outside diameter side occurs at the base end side of the crimped portion 65 as well. The outer peripheral portion of the outer joint member 40 partially satisfies the unevenness of the torque transmission means 51 (female serration 53) on the hub wheel 10 side in the vicinity of the shaft end (the filling portion 69 is represented by a dotted pattern). That is, the outer peripheral meat portion bites into the vicinity of the end portion on the outboard side of the unevenness (the valley portion or the tooth tip surface of the female serration 53) formed on the inner periphery of the hub wheel 10 and closely adheres to the surface thereof. Therefore, the rattling in the circumferential direction between the hub wheel 10 and the outer joint member 40 is reduced, the rigidity of the wheel bearing device is increased, the feeling during operation is improved, the wear of the torque transmission means 51 is avoided, and the like. Can be achieved. The fitting portion between the hub wheel 10 and the outer joint member 40 only needs to be finished to the same degree of accuracy as a normal product, and high accuracy is required for the coaxiality and the like as in the conventional product shown in FIG. Therefore, a significant increase in production cost can be avoided. Further, since the hub wheel 10 and the outer joint member 40 are in close contact with each other in the sufficient portion 69, the full portion 69 can receive a radial load as in the fitting portion 61. Therefore, it is possible to support the radial load on both axial sides of the torque transmitting means 51 together with the fitting portion 61, and the bending rigidity (moment load capacity) of the entire bearing device is thereby increased.
[0028]
In the above description, swing caulking is exemplified as the caulking method, but other caulking methods may be adopted as long as the torque transmission means 51 on the hub wheel 10 side can be satisfied.
[0029]
As shown in FIG. 2, a stepped portion 71 whose diameter is increased on the outboard side is provided on the inner periphery of the shaft end of the outer joint member 40 due to the relationship with the inner diameter of the central portion of the shaft. In this case, the region on the outboard side from the stepped portion 71 is plastically deformed to the outer diameter side. In FIG. 2, the stepped portion 71 is disposed in the vicinity of the end face 10a of the hub wheel 10, but in FIG. 3, the stepped portion 71 is disposed further on the inboard side than in FIG. 2, and the plastic deformation region is expanded on the inboard side. I am letting. In this case, since the region of the sufficient portion 69 after crimping is also expanded to the inboard side, a higher padding effect is obtained. FIG. 4 shows an example in which a jig such as a punch 73 is used after swinging and caulking to expand the diameter of the shaft end of the outer joint member 40 so that the shaft end is more firmly satisfied. FIG. 5 shows an example in which the female serration 53 of the hub wheel 10 is cut off on the inboard side rather than reaching the end surface 10a of the hub wheel 10. In this case, since the filling portion 69 also needs to be displaced to the inboard side, a jig such as a punch 73 is used as in FIG. 4, and the shaft end of the outer joint member 40 is expanded to be firmly filled. .
[0030]
By the way, when caulking the caulking part 65 as described above, it is necessary to take measures against caulking cracks. The caulking crack is a phenomenon in which the caulking portion 63 is cracked during caulking or during use of the bearing after caulking. As a factor, the concentration of deformation distortion can be considered first. In other words, when caulking, due to the difference in rigidity between the shaft end portion of the male serration 55 and the smooth caulking portion 65, the step distortion is concentrated on the boundary portion, and this portion is accompanied by caulking. Since it is greatly deformed, the caulking portion 63 is likely to be cracked.
[0031]
As a countermeasure, as shown in FIGS. 6 and 7, for example, the outer periphery of the stem portion 45 (in this embodiment, the outer periphery of the tightened portion 65) is connected to the groove bottom of the male serration 55 on the shaft end side of the male serration 55. In addition to the male serration 55 of the outer joint member 40, the shaft end side (left of the drawing) of the stem 45 has a cut-out structure, and the cut-out portion 52 is formed from the end face 10 a of the hub wheel 10. Also, a structure that is arranged on the inboard side can be considered. Here, the “cut-out structure” means a structure in which the groove bottom 55a of the male serration 55 is cut through straight in parallel to the axial direction and opened in the outer peripheral region of the crimped portion 65. Thus, by arranging the end portion (cut-out portion 52) on the shaft end side of the groove bottom 55a of the male serration 55 on the inboard side with respect to the hub wheel end surface 10a, deformation during caulking is a smooth cylindrical shape. Since it mainly occurs at the portion to be crimped 65, it is possible to reduce the concentration of shear strain and avoid the occurrence of cracks.
[0032]
As a second factor of the caulking crack, it is conceivable that the torque sharing at the shaft end of the serration fitting portion 51 becomes excessive. That is, in normal serration fitting, the male / female serration portions 55 and 53 are loosely fitted in the circumferential direction, which causes rattling, but when the female serration 53 is satisfied by plastic flow by caulking as described above. Since the clearance in the circumferential direction between the two serrations 53 and 55 is reduced and there is no backlash, the torque sharing at this portion increases.
[0033]
As a countermeasure against this, it is conceivable that the serrations 53 and 55 are fitted with a tightening margin on the opposite side of the shaft end, that is, the inboard side, of the serration fitting portion. As a result, an interference fitting portion is formed at the inboard side end portion of the serration fitting portion, and the torque is also shared in this portion, so that the torque sharing in the sufficiency portion 69 can be reduced and the caulking portion It is possible to avoid 63 cracks.
[0034]
As a method of forming an interference fitting part on the inboard side, for example, it is considered that either one of the male serration 55 and the female serration 53 is slightly inclined with respect to the axis so that the serration has a twist angle. It is done. In this case, in addition to tilting over the entire length of the serration, only the inboard side portion may be tilted, and both the serrations 53 and 55 may be formed parallel to the axial direction on the outboard side.
[0035]
In addition, it is also possible to prevent caulking cracks by considering the limit value of the strain rate of the caulking portion 63 and determining the limit value of the processing speed during caulking.
[0036]
The hub wheel 10 is formed by forging using carbon steel having a carbon content of 0.45 to 0.80% by weight, and starts from the vicinity of the base end portion of the flange 14 to face the seal 26 (seal Surface), the inner race 12, and a region from the abutting surface to the shoulder surface 44 of the outer joint member 40, a hardened layer of about Hv 510 to 900 is formed by heat treatment such as induction hardening. Among these, the end surface of the small end portion of the hub wheel 10 (abutting surface with the shoulder surface 44) is hardened to HRC 50 or more, preferably HRC 58 or more, in order to prevent a decrease in preload due to wear of the end surface. The same hardened layer (Hv 510 to 900) is also formed in the cylindrical inner peripheral surface of the fitting portion 61 and the female serration portion 53 in the inner peripheral surface of the hub wheel 10. Among these, the cylindrical inner peripheral surface of the fitting portion 61 is fretting, abnormal noise, and life reduction of the inner peripheral surface of the fitting portion 61 when a bending moment is applied to the inner races 12 and 42 via the balls 29. Is cured to HRC 50 or more, preferably HRC 58 or more, and the female serration portion 53 can transmit sufficient torque even with a short serration fitting length (about a few tens of millimeters), and wear and wear. Is cured to HRC 50 or more.
[0037]
The outer joint member 40 is also formed by forging using carbon steel having a carbon content of 0.45 to 0.80% by weight, similarly to the hub wheel 10, and subjected to heat treatment such as induction hardening. The hardened layer by the heat treatment starts from the surface (seal surface) facing the seal 28, and has an Hv of about 510 to 900 in the region extending from the inner race 42, the shoulder surface 44, the fitting portion 61 (cylindrical outer peripheral surface), and the male serration 55. To be formed. On the other hand, since the shaft end of the stem portion 45 (the caulking portion 65) serving as the caulking portion 63 is a portion to be caulked, ductility is necessary. The material hardness (Hv 200 to about 300) is maintained.
[0038]
In the above embodiment, the abutting portion between the small-diameter side end surface of the hub wheel 10 and the shoulder surface 44 of the outer joint member 40 is provided so that the axial lengths of the torque transmission means 51 and the fitting portion 16 can be sufficiently secured. It is desirable to provide the inboard side with respect to the center line P of the pitch between the balls 29.
[0039]
FIG. 8 is an example in which a solid portion 47 is partially formed at the shaft end (left side of the drawing) of the stem portion 45 of the outer joint member 40 in the wheel bearing for driving wheels shown in FIG. The solid portion 47 is for improving the workability when the male serration 55 on the outer periphery of the stem portion 45 is processed by rolling or the like, and the male serration 55 is partially or entirely (for this purpose) A part of the solid portion 47 is included in the outer peripheral region of the solid portion 47.
[0040]
FIG. 9 is an example in which an uneven portion 75 is interposed on the fitting surface between the hub wheel 10 and the outer joint member 40, and the fitting surface is partially expanded to include the uneven portion 75 and crimped. is there. The concavo-convex portion 75 is formed by, for example, performing knurling on the outer peripheral surface of the stem portion 45 of the outer joint member 40. For example, the fitting surface is subjected to diameter caulking by press-fitting a caulking jig having an outer diameter larger than the inner diameter of the through-hole 46 into the through-hole 46 and inserting the stem 45 into the outer diameter from the inner diameter side. This is done by expanding the diameter to the side. By this caulking, the uneven portion 75 of the stem portion 45 bites into the inner peripheral surface of the hub wheel 10, so that the hub wheel 10 and the outer joint member 40 are plastically coupled. By the biting of the concavo-convex portion 75, torque can be transmitted between the hub wheel 10 and the stem portion 45, so that the concavo-convex portion 75 also functions as the torque transmitting means 51 of FIG.
[0041]
After completion of the above-described diameter expansion caulking, as in FIG. 1, the shaft end of the stem portion 45 protruding from the end surface 10a of the hub wheel 10 is caulked to the outer diameter side by swing caulking or the like to form the hub wheel end surface 10a. By engaging, the concave and convex portion 75 as the torque transmitting means 51 is further satisfied, so that a strong coupling force can be obtained as in FIG.
[0042]
In addition to expanding the diameter of the fitting surface in which the concave and convex portions 75 are interposed, the diameter of the fitting surface is reduced, for example, by fitting the hub wheel 10 by reducing the diameter from the outer diameter side to the inner diameter side. The same effect can be obtained by reducing the diameter of the surface. In the uneven portion 75, work hardening occurs due to uneven processing, but if this portion is further subjected to a hardening treatment by heat treatment such as induction hardening, the uneven portion 75 is hard to be crushed and firmly bites into the mating surface on the other side, A stronger plastic bond is achieved.
[0043]
FIG. 10 shows a drive wheel bearing device in which the hub wheel 10 is fitted to the inner periphery of the outer joint member 40. One end (inboard side) of the hub wheel 10 is caulked and the mouth portion of the outer joint member 40 is shown. 43 is an example of engagement with the bottom. Also in this case, as in FIGS. 1 and 6, torque transmission means 51 (FIG. 7 shows the case of serration) is interposed between the hub wheel 10 and the outer joint member 40, and the inner periphery of the outer joint member 40 is inserted. By satisfying the provided female serration by caulking in the vicinity of the caulking portion 63, a strong coupling force can be obtained. Since other configurations and operations are the same as those of the embodiment shown in FIGS. 1 and 6, common members are denoted by the same reference numerals, and redundant description is omitted.
[0044]
【The invention's effect】
As described above, in the present invention, the torque transmission means is satisfied in the vicinity of the caulking portion by the plastic deformation accompanying the caulking, so that the rattling in the circumferential direction between the hub wheel and the outer joint member is reduced. It is done. Therefore, the coupling strength between the hub wheel and the outer joint member is improved, and the rigidity of the wheel bearing device is increased. In addition, the fitting portion between the hub wheel and the outer joint member only needs to be finished with the same accuracy as that of a normal product, so that the manufacturing cost is not significantly increased.
[0045]
If the groove end on the shaft end side of the serration is arranged on the inboard side with respect to the end surface of the hub wheel in a state where the shaft end side of the serration of the outer joint member is cut out, It is possible to avoid concentration of shear load in the case, and it is possible to prevent the occurrence of caulking cracks and to increase the bonding strength between the hub wheel and the outer joint member. A similar effect can also be realized by fitting at least the side opposite to the shaft end of the serration fitting portion with a tightening margin.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a drive wheel bearing device according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a fitting portion between a hub wheel and an outer joint member.
FIG. 3 is an enlarged cross-sectional view of a fitting portion between a hub wheel and an outer joint member.
FIG. 4 is an enlarged cross-sectional view of a fitting portion between a hub wheel and an outer joint member.
FIG. 5 is an enlarged cross-sectional view of a fitting portion between a hub wheel and an outer joint member.
FIG. 6 is an enlarged cross-sectional view of a fitting portion between a hub wheel and an outer joint member.
FIG. 7 is an enlarged plan view in which a shaft end portion of a male serration is developed.
FIG. 8 is a cross-sectional view showing another embodiment of a drive wheel bearing device.
FIG. 9 is a cross-sectional view showing another embodiment of a drive wheel bearing device.
FIG. 10 is a cross-sectional view showing another embodiment of a drive wheel bearing device.
FIG. 11 is a cross-sectional view showing a swing caulking process.
FIG. 12 is a cross-sectional view showing an example of a conventional drive wheel bearing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Hub wheel 12 Inner race 20 Bearing 30 Constant velocity universal joint 40 Outer joint member 42 Inner race 51 Torque transmission means 52 Cut-out part 53 Female serration 55 Male serration 55a Groove bottom 61 Fitting part 63 Fastening part 65 Fastening part 75 Uneven part

Claims

In a bearing device for a drive wheel in which a hub wheel, a constant velocity universal joint, and a double row bearing are unitized, and at least an outboard side inner race is formed on the hub wheel among the double row inner races of the bearing,
Either one of the hub wheel and the outer joint member is fitted to the outer periphery of the other via serration, male serration is formed on the inner peripheral member, and male serration is fitted to the outer peripheral member. In addition, a female serration with a constant tooth tip surface diameter is formed, and the shaft end side is made smaller than the male serration groove diameter of the male serration of the inner peripheral side member, and the shaft end is caulked to the shaft end. A portion between the crimped portion of the member on the inner peripheral side and the male serration is opposed to the female serration, and the shaft bottom end portion of the male serration on the shaft end side is more than the end surface of the outer peripheral side member. It is arranged on the opposite side to the side, and the caulking portion of the inner peripheral member is caulked to join the inner peripheral member and the outer peripheral member, and the female serration is caulked in the vicinity of the caulking portion. A bearing device for a drive wheel, characterized by being satisfied by the accompanying plastic deformation.

2. A bearing device for a drive wheel according to claim 1, further comprising a fitting portion in which the caulking portion is fitted on one side in the axial direction of the serration fitting portion and the hub wheel and the outer joint member are fitted on the other side without rattling. .

The bearing device for a drive wheel according to claim 1 or 2 , wherein a hub wheel is fitted on an outer periphery of the outer joint member, and a shaft end of the outer joint member is swaged to be engaged with the hub wheel.

The bearing device for a drive wheel according to claim 1 or 2 , wherein an outer joint member is fitted to the outer periphery of the hub wheel, and an end portion of the hub wheel is crimped to be engaged with the outer joint member.

The drive wheel bearing device according to claim 3 or 4, wherein the caulking portion is made as hard as a material before heat treatment.