JP4221831B2

JP4221831B2 - Rolling bearing unit for wheels

Info

Publication number: JP4221831B2
Application number: JP23430199A
Authority: JP
Inventors: 英男大内
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 1999-08-20
Filing date: 1999-08-20
Publication date: 2009-02-12
Anticipated expiration: 2019-08-20
Also published as: JP2001058506A

Description

【０００１】
【発明の属する技術分野】
この発明に係る車輪用転がり軸受ユニットは、ＦＦ車（前置エンジン前輪駆動車）又は４ＷＤ車（四輪駆動車）の前輪を、懸架装置に対して回転自在に支持する為に利用する。
【０００２】
【従来の技術】
車輪を懸架装置に対して回転自在に支持する為に、外輪と内輪とを転動体を介して回転自在に組み合わせた車輪用転がり軸受ユニットが、各種使用されている。又、操舵輪であると同時に駆動輪でもあるＦＦ車或は４ＷＤ車の前輪を支持する為の車輪用転がり軸受ユニットは、等速ジョイントと組み合わせて、車輪に付与された舵角に拘らず、駆動軸の回転を上記車輪に対して円滑に（等速性を確保して）伝達する必要がある。この様な等速ジョイントと組み合わせて、しかも比較的小型且つ軽量に構成できる車輪用転がり軸受ユニットとして従来から、特開平１１−３７１４６号公報に記載されたものが知られている。
【０００３】
図４は、この公報に記載された従来構造を示している。車両への組み付け状態で、懸架装置に支持した状態で回転しない外輪１（外輪相当部材）は、外周面にこの懸架装置に支持する為の第一の取付フランジ２を、内周面に複列の外輪軌道３、３を、それぞれ有する。上記外輪１の内径側には、第一、第二の内輪部材４、５を組み合わせて成るハブ６（内輪相当部材）を配置している。このうちの第一の内輪部材４は、外周面の外端寄り（外端とは、自動車への組み付け状態で車両の幅方向外側となる端を言い、図４の左端。又、請求項の「一端」に相当する。）部分に車輪を支持する為の第二の取付フランジ７を、同じく内端寄り（内端とは、自動車への組み付け状態で、車両の幅方向中央寄りとなる端部を言い、図４の右端。又、請求項の「他端」に相当する。）部分に第一の内輪軌道８を、それぞれ設けた円筒状に形成している。そして、この第一の内輪部材４の内周面の中間部に雌スプライン部９を、同じく内端部にこの雌スプライン部９よりも大径の内方側円筒面部１０を、互いに同心に設けている。
【０００４】
これに対して、上記第二の内輪部材５は、外端部を上記第一の内輪部材４をがたつきなく外嵌固定する為の嵌合支持部１１とし、内端部を等速ジョイント１２の外輪となるハウジング部１３とし、中間部外周面に第二の内輪軌道１４を設けている。又、上記嵌合支持部１１の外周面の中間部に、上記雌スプライン部９とスプライン係合する雄スプライン部１５を、同じく基端部に、上記内方側円筒面部１０と嵌合する外方側円筒面部１６を、互いに同心に設けている。又、上記嵌合支持部１１の先端部は、上記雄スプライン部１５よりも小径の雄ねじ部１７としている。
【０００５】
上記第一の内輪部材４と上記第二の内輪部材５とを結合してハブ６とする際には、上記嵌合支持部１１を上記第一の内輪部材４の内径側に挿通し、上記雌スプライン部９と上記雄スプライン部１５とをスプライン係合させると共に、上記内方側円筒面部１０と上記外方側円筒面部１６とを締り嵌めにより嵌合させる。これと共に、上記雄ねじ部１７にナット１８を螺合し、更に緊締する事により、上記第一の内輪部材４と上記第二の内輪部材５とを結合する。
【０００６】
そして、上記各外輪軌道３、３と上記第一、第二の内輪軌道８、１４との間にそれぞれ複数個ずつの転動体１９、１９を転動自在に設ける事により、前記外輪１の内周面と上述の様に構成するハブ６の外周面との間に、複列外向き（背面組み合わせ型の）アンギュラ玉軸受を設けている。これにより、上記ハブ６を、上記外輪１の内径側に、回転自在に支持している。更に、上記外輪１の両端開口部と上記ハブ６の中間部外周面との間には、ステンレス鋼板等の金属製で略円筒状のカバー２０ａ、２０ｂと、ゴムの如きエラストマー等の弾性材製で円環状のシールリング２１ａ、２１ｂとを設けている。これらカバー２０ａ、２０ｂ及びシールリング２１ａ、２１ｂは、上記複数の転動体１９、１９を設置した部分と外部とを遮断し、この部分に存在するグリースが外部に漏出するのを防止すると共に、この部分に雨水、塵芥等の異物が侵入する事を防止する。又、上記第二の内輪部材５の中間部内側には、この第二の内輪部材５の内側を塞ぐ隔板部２２を設けて、この第二の内輪部材５の剛性を確保すると共に、この第二の内輪部材５の外端開口からこの第二の内輪部材５の内側に入り込んだ異物が、前記ハウジング部１３の内側に設けた等速ジョイント１２部分にまで達する事を防止している。
【０００７】
又、上記等速ジョイント１２は、前記ハウジング部１３と、内輪２３と、保持器２４と、複数個の玉２５とから成る。このうちの内輪２３は、エンジンによりトランスミッション及びデファレンシャルギヤを介して回転駆動される、図示しない駆動軸の先端部に固定される。この内輪２３の外周面には、それぞれが断面円弧形である複数本の内側係合溝２６を、円周方向に亙り等間隔に、それぞれ円周方向に対し直角方向に形成している。又、上記ハウジング部１３の内周面で上記内側係合溝２６と対向する位置には、やはりそれぞれが断面円弧形である複数本の外側係合溝２７を、円周方向に対し直角方向に形成している。又、上記保持器２４は、断面円弧状で全体を円環状に形成しており、上記内輪２３の外周面とハウジング部１３の内周面との間に挟持している。この保持器２４の円周方向複数個所で、上記内側、外側両係合溝２６、２７に整合する位置には、それぞれポケット２８を形成し、これら各ポケット２８の内側にそれぞれ１個ずつ、上記玉２５を保持している。これら各玉２５は、それぞれ上記各ポケット２８に保持された状態で、上記内側、外側両係合溝２６、２７に沿い転動自在である。
【０００８】
上述の様に構成する車輪用転がり軸受ユニットを車両に組み付ける際には、第一の取付フランジ２により外輪１を懸架装置に支持し、第二の取付フランジ７により駆動輪でもある前輪を第一の内輪部材４に固定する。又、エンジンによりトランスミッションを介して回転駆動される、図示しない駆動軸の先端部を、等速ジョイント１２を構成する内輪２３の内側にスプライン係合させる。自動車の走行時には、上記内輪２３の回転を、複数の玉２５を介して第二の内輪部材５を含むハブ６に伝達し、上記前輪を回転駆動する。
【０００９】
【発明が解決しようとする課題】
上述した様な従来構造の場合、前記内方側円筒面部１０と前記外方側両円筒面部１６との嵌合部３７は、上記第一の内輪部材４と前記第二の内輪部材５との結合部のがたつきを抑えると共に、これら両内輪部材４、５同士を結合して成る、ハブ６の曲げ剛性を向上させる為の部位である。従って、このハブ６の曲げ剛性を十分に確保する為には、上記嵌合部３７に大きなモーメントが加わらない様な設計を行ない、この嵌合部３７の耐久性を十分に確保する必要がある。ところが、従来は、この様な嵌合部３７の耐久性を確保する為の設計が、積極的に行なわれてはいなかった。
【００１０】
上述の様な嵌合部３７の耐久性を確保する為の設計を行なう場合には、この嵌合部３７にどの様なモーメントが加わるかを十分に検討する必要がある。そこで、自動車の走行頻度の高い直進走行時に、上記嵌合部３７にどの様なモーメントが加わるかに就いて、図５を参照しつつ、以下に検討する。先ず、上記従来構造を構成するハブ６には、路面から鉛直方向上向きの反力Ｎが、車輪を構成するタイヤのトレッド面を介して加わる。尚、この反力Ｎを表すベクトルは、上記タイヤの接地点中心（上記トレッド面と路面との接触部のうち、この路面からトレッド面に加わるラジアル荷重の重心が存在する部分）を通る鉛直線α上に存在する。これと共に、上記ハブ６には、外側（図５の左側）、内側（図５の右側）の各転動体列から、それぞれ鉛直方向下向きのラジアル荷重Ｆ_R1、Ｆ_R2と、互いに軸方向逆向きのスラスト荷重Ｆ_A1、Ｆ_A2とが加わる。尚、これら各荷重Ｆ_R1、Ｆ_A1、Ｆ_R2、Ｆ_A2は、それぞれ上記各転動体列の作用点（転動体列を構成する各転動体１９、１９の接触線と、この転動体列の中心軸との交点）Ｏ₁ 、Ｏ₂ に加わる。
【００１１】
次に、便宜上、前記第二の内輪部材５が前記第一の内輪部材４に、上記嵌合部３７で支持されていると考えると、この嵌合部３７には、上記内側の転動体列から作用するラジアル荷重Ｆ_R2に基づき、Ｆ_R2・Ｓ₂ なる大きさのモーメントＭ₂ が加わる。ここで、Ｓ₂ は、上記嵌合部３７の軸方向に関する中心点Ｏ₃₇と上記内側の転動体列の荷重の作用点Ｏ₂ との間の、軸方向に亙る間隔である。尚、上記作用点Ｏ₂ に加わるスラスト荷重Ｆ_A2は、上記嵌合部３７に加わるモーメントとしては作用しない。上述の様に、便宜上、上記第二の内輪部材５が上記第一の内輪部材４に、上記嵌合部３７で支持されていると考えた理由は、この様に考えれば、この嵌合部３７に加わるモーメントに寄与する荷重が上記内側の転動体列から作用するラジアル荷重Ｆ_R2のみとなって、上記嵌合部３７に加わるモーメントを考え易くなる為である。
【００１２】
反対に、上記第一の内輪部材４が上記第二の内輪部材５に、上記嵌合部３７で支持されていると考えると、この嵌合部３７には、上記外側の転動体列から作用するラジアル荷重Ｆ_R1に基づき、Ｆ_R1・Ｓ₁ なる大きさのモーメントＭ₁ が加わる。ここで、Ｓ₁ は、上記中心点Ｏ₃₇と上記外側の転動体列の荷重の作用点Ｏ₁ との間の、軸方向に亙る間隔である。尚、この場合も、上記作用点Ｏ₁ に加わるスラスト荷重Ｆ_A1は、上記嵌合部３７に加わるモーメントとしては作用しない。これと共に、上記嵌合部３７には、上記路面からの反力Ｎに基づき、Ｎ・Ｓ₃ なる大きさのモーメントＭ₃ が加わる。ここで、Ｓ₃ は、上記中心点Ｏ₃₇と上記タイヤの接地点中心を通る鉛直線αとの間の、軸方向に亙る間隔である。この結果、上述の様に第一の内輪部材４が第二の内輪部材５に、上記嵌合部３７で支持されていると考えた場合、上記嵌合部３７には、上記両モーメントＭ₁ 、Ｍ₃ を合成した、モーメントＭ₁ ′｛＝Ｍ₁ −Ｍ₃ （モーメントＭ₁ の向きを正にとった。）｝が加わる。
【００１３】
上述の様に嵌合部３７に加わるモーメントの種類｛Ｍ₁ ′（＝Ｍ₁ −Ｍ₃ ）、Ｍ₂ ｝が分かったので、次に、上記嵌合部３７の耐久性を十分に確保する為の手段に就いて検討する。この嵌合部３７の耐久性を十分に確保する為には、この嵌合部３７に加わる、上記各モーメントＭ₁ ′、Ｍ₂ の大きさを小さくすれば良い。又、この場合、釣り合いの条件から、上記両モーメントＭ₁ ′、Ｍ₂ の大きさは互いに等しい。従って、上記嵌合部３７の耐久性を十分に確保する為には、上記各モーメントＭ₁ ′、Ｍ₂ のうちの何れか一方のモーメントの大きさを小さくする設計を行なえば良い。
本発明の車輪用転がり軸受ユニットは、上述の様な検討の末になされたものである。
【００１４】
【課題を解決するための手段】
本発明の車輪用転がり軸受ユニットは、前述した従来構造と同様に、外周面に懸架装置に支持する為の第一の取付フランジを、内周面に複列の外輪軌道を、それぞれ有し、使用時にも回転しない外輪相当部材と、外周面の外端寄り部分に車輪を支持する為の第二の取付フランジを、同じく中間部に複列の内輪軌道を、それぞれ設け、内端部を等速ジョイントの外輪となるハウジング部とした、使用時に回転する内輪相当部材と、上記各外輪軌道と上記各内輪軌道との間にそれぞれ複数個ずつ転動自在に設けられた転動体とを備える。そして、このうちの内輪相当部材は、第一の内輪部材と第二の内輪部材とを組み合わせて成り、このうちの第一の内輪部材は、外周面の外端寄り部に上記第二の取付フランジを、同じく内端寄り部に上記複列の内輪軌道のうちの一方の内輪軌道を、それぞれ設けた筒状に形成すると共に、内周面の中間部に雌スプライン部を、同じく内端部にこの雌スプライン部よりも大径の内方側円筒面部を、互いに同心に設けたものであり、上記第二の内輪部材は、外端部を上記第一の内輪部材をがたつきなく外嵌固定する為の嵌合支持部とし、中間部外周面に上記複列の内輪軌道のうちの他方の内輪軌道を設け、内端部を上記ハウジング部とすると共に、上記嵌合支持部の外周面に、上記雌スプライン部とスプライン係合する雄スプライン部と、上記内方側円筒面部と締め代を持って嵌合する外方側円筒面部とを、互いに同心に形成したものである。
特に、本発明の車輪用転がり軸受ユニットに於いては、上記内方側、外方側両円筒面部同士の嵌合部の他端縁を、複列の転動体列同士の間部分の軸方向中央位置よりも他端側に位置させると共に、上記第二の取付フランジに支持した車輪を構成するタイヤの接地点中心（このタイヤのトレッド面と路面との接触部のうち、この路面からトレッド面に加わるラジアル荷重の重心が存在する部分）を通る鉛直線を、上記複列の転動体列同士の間部分で、この間部分の軸方向中央位置よりも一端側に位置させている。
【００１５】
【作用】
上述の様に構成する本発明の車輪用転がり軸受ユニットによれば、内方側、外方側両円筒面部同士の嵌合部に加わるモーメントを十分に小さくできる。この為、上記嵌合部の耐久性を十分に確保して、内輪相当部材の曲げ剛性が低下する事を防止できる。
【００１６】
【発明の実施の形態】
図１は、本発明の実施の形態の第１例を示している。尚、本発明の特徴は、内方側、外方側両円筒面部１０、１６同士の嵌合部３７と、車輪を構成するタイヤの接地点中心を通る鉛直線αと、複列に亙り設けた転動体１９、１９の軸方向中央位置との、それぞれの位置関係を規制した点にある。その他の部分の構造及び作用は、前述した従来構造の場合と同様であるから、重複する部分の説明は省略若しくは簡略にし、以下、本発明の特徴部分、並びに上記従来構造と異なる部分を中心に説明する。
【００１７】
第一の内輪部材４ａの外端寄り部（図１の左寄り部）外周面に形成した第二の取付フランジ７には、自動車の車輪を構成するホイール２９及び制動装置であるディスクブレーキを構成するロータ３０を、複数本のスタッド３１とナット３２とにより支持固定している。又、上記ホイール２９の外径側部分には、図示しないタイヤを組み付けている。又、本発明の場合、このタイヤの接地点中心を通る鉛直線αが、複列の転動体列同士の間部分（各列の転動体１９、１９の中心点同士の間部分）には存在するが、この間部分の軸方向中央位置（鉛直線β）よりも軸方向外側（図１の左側）に位置する様に、車輪用転がり軸受ユニットの各部の寸法を規制している。これと共に、上記嵌合部３７の内端縁（図１の右端縁）を、上記鉛直線βよりも軸方向内側（図１の右側）に位置させている。そして、この様な構成を採用する事により、上記嵌合部３７に加わるモーメントを小さくして、この嵌合部３７の耐久性を十分に確保している。尚、図示の例では、上記鉛直線α、βが、何れもこの嵌合部３７を通過する様にしている。上述の様な構成を採用する事により、上記嵌合部３７に加わるモーメントを小さくできる理由に就いては、後述する。
【００１８】
又、上述の様に嵌合部３７の内端縁を上記鉛直線βよりも軸方向内方に位置させる為に、本例の場合には、この嵌合部３７の全体を軸方向内方にずらす事はせず、この嵌合部３７（即ち、上記内方側、外方側両円筒面部１０、１６）の内端縁を軸方向内方に延長させて、この嵌合部３７全体の軸方向寸法を大きくしている。図示の例では、上記嵌合部３７の内端縁を十分に延長させるべく、この嵌合部３７の内端縁部分に存在する、第一の内輪部材４ａの内端面と第二の内輪部材５ａの中間部外周面に形成した段部３３との当接部を、内側（図１の右側）の転動体列の近傍部分にまで近づけて配置している。この様に本例の場合には、上記嵌合部３７の軸方向寸法を大きくしている為、上記第二の内輪部材５ａに対する上記第一の内輪部材４ａの支持強度、並びに上記嵌合部３７のモーメント荷重に対する負荷能力を十分に大きくできる。尚、上述の様に嵌合部３７の軸方向寸法を大きくする手段としては、この嵌合部３７の外端縁を軸方向外方に延長させる事も有効である。この場合、組み立て時に於ける雌スプライン部９と雄スプライン部１５との係合等を考慮しても、設計上可能であれば、この嵌合部３７の外端縁を外側（図１の左側）の転動体列よりも更に軸方向外方に延長させる事が、上記嵌合部３７の軸方向寸法を十分に確保する上で好ましい。
【００１９】
尚、本例の場合、上記第一、第二の内輪部材４ａ、５ａを結合してハブ６ａとすべく、この第一の内輪部材４ａの内端面と上記段部３３とを当接させた状態で、各転動体１９、１９に適切な予圧が付与される様に、各部の寸法を規制している。又、本例の場合、上記嵌合部３７に持たせる締め代の大きさを、１５〜４０μｍ程度と大きくする事により、この嵌合部３７の嵌合強度を十分に確保している。又、上記内方側、外方側両円筒面部１０、１６の表面に、それぞれ高周波焼き入れ等による硬化処理を施している。これにより、これら両円筒面部１０、１６に、上記嵌合部３７に加わる大きな接触面圧に耐え得る強度を付与している。
【００２０】
上述の様に構成する本例の車輪用転がり軸受ユニットの場合には、上記嵌合部３７に加わるモーメントを小さくできる。この理由に就いて、前述の図５を参照しつつ、以下に説明する。タイヤの接地点中心から加わる反力Ｎは、複列の転動体列の作用点Ｏ₁ 、Ｏ₂ に加わるラジアル荷重Ｆ_R1、Ｆ_R2として分配される。本発明の様に上記反力Ｎ（前記鉛直線α上のベクトル）が、複列の転動体列同士の間部分で、この間部分の軸方向中央位置よりも軸方向外方にずれている場合には、上記内側の転動体列の作用点Ｏ₂ に加わるラジアル荷重Ｆ_R2が、外側の転動体列の作用点Ｏ₁ に加わるラジアル荷重Ｆ_R1よりも小さくなる。この為、上記内側の転動体列の作用点Ｏ₂ に加わるラジアル荷重Ｆ_R2に基づいて、上記嵌合部３７に作用するモーメントＭ₂ （＝Ｆ_R2・Ｓ₂ ）を小さくできる。
【００２１】
更に、本例の場合、上記嵌合部３７の内端縁を上記複列の転動体列同士の間部分の軸方向中央位置よりも軸方向内方に位置させている。この為、この嵌合部３７の軸方向に関する中心点Ｏ₃₇が上記内側の転動体列の作用点Ｏ₂ に近づき、これら両点Ｏ₃₇、Ｏ₂ 同士の軸方向に亙る間隔Ｓ₂ が小さくなる。この為、やはり、上記ラジアル荷重Ｆ_R2に基づいて上記嵌合部３７に作用するモーメントＭ₂ （＝Ｆ_R2・Ｓ₂ ）を小さくできる。一方、前述の［本発明が解決しようとする課題］の部分で説明した様に、上記嵌合部３７には、上記反力Ｎ及び外側の転動体列の作用点Ｏ₁ に作用するラジアル荷重Ｆ_R1に基づくモーメントＭ₁ ′が加わる。この場合、釣り合いの条件から、上記両モーメントＭ₁ ′、Ｍ₂ の大きさは互いに等しい。従って、上記モーメントＭ₂ を小さくした事に伴い、上記モーメントＭ₁ ′も小さくできる。この為、本例の場合には、上記嵌合部３７に加わるモーメントを小さくでき、この嵌合部３７の耐久性を十分に確保できる。
【００２２】
尚、上述の説明では、各部分に加わる荷重やモーメントに就いて、自動車の走行頻度の高い直進走行時に加わるものだけを考慮した。これに対して、自動車が旋回走行する場合には、図２に示す様に、自動車３８に遠心力Ｆが加わり、車輪を構成するタイヤ３９ａ、３９ｂには、路面からの反力としてラジアル荷重Ｒ₁ 、Ｒ₂ の他に、スラスト荷重Ａ₁ 、Ａ₂ が加わる。又、上述の様な遠心力Ｆが上記自動車３８の重心に作用する事に基づき、車体がロールして荷重移動する為、旋回方向外周側（図２の左側）のタイヤ３９ｂの接地圧の方が、内周側（図２の右側）のタイヤ３９ａの接地圧よりも高くなる。この為、旋回方向外周側のタイヤ３９ｂに加わる路面からの反力Ｒ₂ 、Ａ₂ の方が、旋回方向内周側のタイヤ３９ａに加わる路面からの反力Ｒ₁ 、Ａ₁ よりも大きくなる。
【００２３】
そこで、次に、上述の様に路面から大きな反力Ｒ₂ 、Ａ₂ を受ける、旋回方向外周側のタイヤ３９ｂを支持する車輪用転がり軸受ユニットに就いて考える。この旋回方向外周側のタイヤ３９ｂを支持する車輪用転がり軸受ユニットには、路面からこのタイヤ３９ｂに加わるスラスト荷重Ａ₂ に基づいて、モーメント（軸受ユニットの中心軸から接地面までの垂直距離をＸとした場合に、Ａ₂ ・Ｘの大きさのモーメント）が作用する。又、このスラスト荷重Ａ₂ に基づくモーメントは、外側（図５の左側）の転動体列の作用点Ｏ₁ に加わるラジアル荷重Ｆ_R1を低減させつつ、内側（図５の右側）の転動体列の作用点Ｏ₂ に加わるラジアル荷重Ｆ_R2を増大させる方向に作用する。
【００２４】
従って、自動車３８の旋回走行時には、旋回方向外周側のタイヤ３９ｂを支持する車輪用転がり軸受ユニットを構成する、内側の転動体列に最も大きなラジアル荷重が作用する。この為、本発明の場合には、この内側の転動体列の耐久性を確保する観点からも、前述した様に鉛直線αを鉛直線βよりも軸方向外方に配置する事により、上記内側の転動体列に作用するラジアル荷重Ｆ_R2を、積極的に小さくする様にしている。尚、本例の様に上記鉛直線α（路面からの反力Ｎ）を上記鉛直線βよりも軸方向外方にずらせる場合には、このずらせる量を調節して、複列の転動体列の剥離寿命に大きな差が生じない様にするのが好ましい。この場合に、上記両鉛直線α、β同士のずれ量は、外側の転動体列と内側の転動体列との作用点間距離をＳ（図５のＳ₁ ＋Ｓ₂ ）とした場合に、この作用点間距離Ｓの５〜１５％程度とするのが好ましい。例えば、一般的な乗用車用の車輪用転がり軸受ユニットの場合で、２〜６mm程度とする。
【００２５】
又、図１に示した本例の場合、上記ハブ６ａに加わるモーメントは、上記内方側、外方側両円筒面部１０、１６同士の嵌合部３７で支承する他、前記第一の内輪部材４ａの内端面と前記段部３３との当接部、並びに嵌合支持部１１の先端部に螺合・緊締したナット１８と上記第一の内輪部材４ａの内周面外端寄り部に設けた段部３４との当接部でも支承する。そこで、これら各当接部で支承し得る上記モーメントの割合を大きくして、上記嵌合部３７に大きなモーメント荷重が加わらない様にすべく、上記両当接部同士の軸方向に亙る間隔Ｌと、これら各当接部の直径方向に亙る幅寸法Ｈ₁₈、Ｈ₃₃とを、それぞれ可及的に大きくするのが好ましい。
【００２６】
尚、実際に本発明を実施する場合、前述した鉛直線αの軸方向に亙る位置は、前記第二の取付フランジ７に支持固定するホイール２９のオフセット量｛このホイール２９の上記第二の取付フランジ７に対する取付面と、このホイール２９の幅方向の中心線（キャンバー角を０と仮定した場合に、上記鉛直線αと一致する直線）との軸方向に亙る間隔｝δの大きさにより異なる。従って、本発明を実施する場合には、上記第二の取付フランジ７に支持するホイール２９のオフセット量δ及びキャンバー角を考慮して、構成各部材の寸法を規制する。
【００２７】
次に、図３は、本発明の実施の形態の第２例を示している。本例の場合、第二の内輪部材５ｂを構成する嵌合支持部１１ａの先半部を円筒部３５とし、この円筒部３５の外周面に雄スプライン部１５を構成する多数の雄スプライン溝を、それぞれこの円筒部３５の（先端部を含んで）全長に亙り形成している。又、この様な円筒部３５の先端部で、第一の内輪部材４ｂの中間部内周面に設けた雌スプライン部９の外端（図２の左端）開口から突出した部分は、直径方向外方に塑性変形させて、かしめ部３６としている。そして、このかしめ部３６と上記第二の内輪部材５ｂの中間部外周面に設けた段部３３との間で上記第一の内輪部材４ｂを挟持する事により、ハブ６ｂとしている。
【００２８】
又、本例の場合、雌スプライン部９には、全長に亙り焼き入れ硬化処理を施しているが、上記雄スプライン部１５には、上記かしめ部３６を形成する先端部を除いた部分にのみ焼き入れ硬化処理を施している。これにより、上記円筒部３５の先端部が直径方向外方に塑性変形できる様にし、上記かしめ部３６の形成を自在としている。尚、本例を実施するに当たり、上記各雄スプライン溝は、上記かしめ部３６を形成する部分である、上記円筒部３５の先端部にまで形成する必要はない。但し、図示の例の場合には、上記各雄スプライン溝の加工を容易にする為に、これら各雄スプライン溝を上記円筒部３５の先端縁まで形成している。この様に構成する本例の場合、上述した第１例に比べて、ナット１８（図１参照）を使わない分、部品点数の削減に伴う軽量化とコスト低減とを図れる。その他の構成及び作用は、上述した第１例の場合と同様である。
【００２９】
【発明の効果】
本発明の車輪用転がり軸受ユニットは、以上に述べた通り構成され作用する為、内方側円筒面部と外方側円筒面部との嵌合部の耐久性を十分に確保して、ハブの剛性が低下する事を防止できる。この結果、車輪用転がり軸受ユニットの耐久性向上を図れる。
【図面の簡単な説明】
【図１】本発明の実施の形態の第１例を示す部分断面図。
【図２】自動車の旋回走行時に加わる力を示す模式図。
【図３】本発明の実施の形態の第２例を示す部分断面図。
【図４】従来構造の１例を示す部分断面図。
【図５】ハブに作用する荷重を示す模式図。
【符号の説明】
１外輪
２第一の取付フランジ
３外輪軌道
４、４ａ、４ｂ第一の内輪部材
５、５ａ、５ｂ第二の内輪部材
６、６ａ、６ｂハブ
７第二の取付フランジ
８第一の内輪軌道
９雌スプライン部
１０内方側円筒面部
１１、１１ａ嵌合支持部
１２等速ジョイント
１３ハウジング部
１４第二の内輪軌道
１５雄スプライン部
１６外方側円筒面部
１７雄ねじ部
１８ナット
１９転動体
２０ａ、２０ｂカバー
２１ａ、２１ｂシールリング
２２隔壁部
２３内輪
２４保持器
２５玉
２６内側係合溝
２７外側係合溝
２８ポケット
２９ホイール
３０ロータ
３１スタッド
３２ナット
３３段部
３４段部
３５円筒部
３６かしめ部
３７嵌合部
３８自動車
３９ａ、３９ｂタイヤ[0001]
BACKGROUND OF THE INVENTION
The wheel rolling bearing unit according to the present invention is used to rotatably support the front wheel of an FF vehicle (front engine front wheel drive vehicle) or a 4WD vehicle (four wheel drive vehicle) with respect to a suspension device.
[0002]
[Prior art]
In order to rotatably support a wheel with respect to a suspension device, various types of wheel rolling bearing units are used in which an outer ring and an inner ring are rotatably combined via rolling elements. In addition, the wheel rolling bearing unit for supporting the front wheel of the FF vehicle or 4WD vehicle which is the steering wheel as well as the driving wheel is combined with the constant velocity joint, regardless of the steering angle given to the wheel. It is necessary to transmit the rotation of the drive shaft to the wheel smoothly (with a constant speed). As a rolling bearing unit for a wheel that can be combined with such a constant velocity joint and can be configured to be relatively small and light, one described in JP-A-11-37146 has been known.
[0003]
FIG. 4 shows a conventional structure described in this publication. The outer ring 1 (outer ring equivalent member) that does not rotate while being supported by the suspension device in the state of being assembled to the vehicle has a first mounting flange 2 for supporting the suspension device on the outer peripheral surface. The outer ring raceways 3 and 3 are respectively provided. On the inner diameter side of the outer ring 1, a hub 6 (an inner ring equivalent member) formed by combining the first and second inner ring members 4, 5 is disposed. Of these, the first inner ring member 4 is close to the outer end of the outer peripheral surface (the outer end is the end that is the outer side in the width direction of the vehicle when assembled to the automobile, and is the left end of FIG. 4. The second mounting flange 7 for supporting the wheel on the “one end” portion is also close to the inner end (the inner end is the end closer to the center in the width direction of the vehicle when assembled to the automobile) 4 and corresponding to the “other end” of the claims.) The first inner ring raceway 8 is formed in a cylindrical shape provided respectively. And the female spline part 9 is provided in the intermediate part of the internal peripheral surface of this 1st inner ring member 4, and the inner side cylindrical surface part 10 larger diameter than this female spline part 9 is similarly provided concentrically with each other. ing.
[0004]
On the other hand, the second inner ring member 5 has an outer end portion as a fitting support portion 11 for externally fixing the first inner ring member 4 without rattling, and the inner end portion is a constant velocity joint. The housing portion 13 is an outer ring 12 and a second inner ring raceway 14 is provided on the outer peripheral surface of the intermediate portion. Further, a male spline portion 15 that is spline-engaged with the female spline portion 9 is provided at an intermediate portion of the outer peripheral surface of the fitting support portion 11, and an outer portion that is similarly fitted with the inner cylindrical surface portion 10 at the base end portion. The side cylindrical surface portions 16 are provided concentrically with each other. Further, the distal end portion of the fitting support portion 11 is a male screw portion 17 having a smaller diameter than the male spline portion 15.
[0005]
When the first inner ring member 4 and the second inner ring member 5 are combined to form the hub 6, the fitting support portion 11 is inserted into the inner diameter side of the first inner ring member 4, The female spline portion 9 and the male spline portion 15 are spline-engaged, and the inner cylindrical surface portion 10 and the outer cylindrical surface portion 16 are fitted by an interference fit. At the same time, the first inner ring member 4 and the second inner ring member 5 are coupled by screwing the nut 18 into the male threaded portion 17 and further tightening.
[0006]
A plurality of rolling elements 19, 19 are provided between the outer ring raceways 3, 3 and the first and second inner ring raceways 8, 14, respectively. A double-row outward (rear combination type) angular ball bearing is provided between the peripheral surface and the outer peripheral surface of the hub 6 configured as described above. Thereby, the hub 6 is rotatably supported on the inner diameter side of the outer ring 1. Further, between the opening portions at both ends of the outer ring 1 and the outer peripheral surface of the intermediate portion of the hub 6, a substantially cylindrical cover 20a, 20b made of a metal such as a stainless steel plate, and an elastic material such as an elastomer such as rubber. Are provided with annular seal rings 21a and 21b. The covers 20a and 20b and the seal rings 21a and 21b block the portion where the plurality of rolling elements 19 and 19 are installed from the outside, and prevent the grease existing in this portion from leaking outside. Prevents foreign matter such as rainwater and dust from entering the area. Further, on the inner side of the intermediate portion of the second inner ring member 5, a partition plate portion 22 that closes the inner side of the second inner ring member 5 is provided to ensure the rigidity of the second inner ring member 5. Foreign matter that has entered the inside of the second inner ring member 5 from the outer end opening of the second inner ring member 5 is prevented from reaching the constant velocity joint 12 provided inside the housing part 13.
[0007]
The constant velocity joint 12 includes the housing portion 13, an inner ring 23, a cage 24, and a plurality of balls 25. Of these, the inner ring 23 is fixed to the tip of a drive shaft (not shown) that is rotationally driven by the engine via a transmission and a differential gear. On the outer peripheral surface of the inner ring 23, a plurality of inner engagement grooves 26, each having an arc shape in cross section, are formed at equal intervals in the circumferential direction and perpendicular to the circumferential direction. Further, a plurality of outer engagement grooves 27 each having an arcuate cross section are formed at a position facing the inner engagement groove 26 on the inner peripheral surface of the housing portion 13 in a direction perpendicular to the circumferential direction. Is formed. The cage 24 has an arc shape in cross section and is formed in an annular shape as a whole, and is held between the outer peripheral surface of the inner ring 23 and the inner peripheral surface of the housing portion 13. Pockets 28 are formed at positions that are aligned with the inner and outer engaging grooves 26 and 27 at a plurality of locations in the circumferential direction of the retainer 24, and one pocket is formed inside each of the pockets 28. The ball 25 is held. These balls 25 can roll along the inner and outer engaging grooves 26 and 27 while being held in the pockets 28, respectively.
[0008]
When the rolling bearing unit for a wheel configured as described above is assembled to a vehicle, the outer ring 1 is supported on the suspension device by the first mounting flange 2 and the front wheel which is also the driving wheel is first supported by the second mounting flange 7. The inner ring member 4 is fixed. Further, the tip of a drive shaft (not shown) that is rotationally driven by the engine via the transmission is spline-engaged with the inner side of the inner ring 23 that constitutes the constant velocity joint 12. During traveling of the automobile, the rotation of the inner ring 23 is transmitted to the hub 6 including the second inner ring member 5 via the plurality of balls 25, and the front wheel is rotated.
[0009]
[Problems to be solved by the invention]
In the case of the conventional structure as described above, the fitting portion 37 between the inner cylindrical surface portion 10 and the outer cylindrical surface portions 16 is formed between the first inner ring member 4 and the second inner ring member 5. This is a portion for suppressing the rattling of the connecting portion and for improving the bending rigidity of the hub 6 formed by connecting the inner ring members 4 and 5 to each other. Therefore, in order to sufficiently secure the bending rigidity of the hub 6, it is necessary to design the fitting portion 37 so that a large moment is not applied to the fitting portion 37 and to ensure the durability of the fitting portion 37 sufficiently. . However, conventionally, such a design for ensuring the durability of the fitting portion 37 has not been actively performed.
[0010]
When designing for ensuring the durability of the fitting portion 37 as described above, it is necessary to sufficiently examine what moment is applied to the fitting portion 37. Therefore, it will be examined below with reference to FIG. 5 what kind of moment is applied to the fitting portion 37 when the automobile is traveling straight ahead with high traveling frequency. First, a reaction force N that is upward in the vertical direction from the road surface is applied to the hub 6 that constitutes the conventional structure via a tread surface of a tire that constitutes a wheel. The vector representing the reaction force N is a vertical line that passes through the center of the ground contact point of the tire (the portion of the contact portion between the tread surface and the road surface where the center of gravity of the radial load applied from the road surface to the tread surface exists). exists on α. At the same time, the hub 6 has a radial load F downward in the vertical direction from the outer (left side in FIG. 5) and inner (right side in FIG. 5) rolling element rows. _R1 , F _R2 And axially opposite thrust loads F _A1 , F _A2 And join. Each of these loads F _R1 , F _A1 , F _R2 , F _A2 Is the point of action of each rolling element row (intersection of the contact line of each rolling element 19, 19 constituting the rolling element row and the central axis of this rolling element row) O ₁ , O ₂ To join.
[0011]
Next, for convenience, when it is considered that the second inner ring member 5 is supported on the first inner ring member 4 by the fitting portion 37, the inner rolling element row is provided in the fitting portion 37. Radial load F acting from _R2 Based on F _R2 ・ S ₂ Moment M of magnitude ₂ Will be added. Where S ₂ Is the center point O in the axial direction of the fitting portion 37. ₃₇ And the point of action O of the load on the inner rolling element row ₂ It is the space | interval which extends in the axial direction between. Note that the point of action O ₂ Thrust load F applied to _A2 Does not act as a moment applied to the fitting portion 37. As described above, for the sake of convenience, the reason why the second inner ring member 5 is supported on the first inner ring member 4 by the fitting portion 37 is that the fitting portion is considered in this way. The radial load F that the load that contributes to the moment applied to 37 acts from the inner rolling element row _R2 This is because it becomes easy to consider the moment applied to the fitting portion 37.
[0012]
On the other hand, when it is considered that the first inner ring member 4 is supported by the second inner ring member 5 by the fitting portion 37, the fitting portion 37 acts on the outer rolling element row. Radial load F _R1 Based on F _R1 ・ S ₁ Moment M of magnitude ₁ Will be added. Where S ₁ Is the center point O ₃₇ And the point of action O of the load on the outer rolling element row ₁ It is the space | interval which extends in the axial direction between. In this case also, the action point O ₁ Thrust load F applied to _A1 Does not act as a moment applied to the fitting portion 37. At the same time, the fitting portion 37 has N · S based on the reaction force N from the road surface. _Three Moment M of magnitude _Three Will be added. Where S _Three Is the center point O ₃₇ And the vertical line α passing through the center of the ground contact point of the tire. As a result, when it is considered that the first inner ring member 4 is supported by the second inner ring member 5 by the fitting part 37 as described above, the fitting part 37 has the both moments M. ₁ , M _Three Is the moment M ₁ '{= M ₁ -M _Three (Moment M ₁ The direction of was taken positively. )} Is added.
[0013]
As described above, the type of moment applied to the fitting portion 37 {M ₁ '(= M ₁ -M _Three ), M ₂ } Next, the means for ensuring sufficient durability of the fitting portion 37 will be examined. In order to ensure sufficient durability of the fitting portion 37, the moments M applied to the fitting portion 37 are as follows. ₁ ', M ₂ The size of can be reduced. In this case, both moments M are determined from the balance condition. ₁ ', M ₂ Are equal in size. Accordingly, in order to sufficiently ensure the durability of the fitting portion 37, each moment M ₁ ', M ₂ Any one of the moments may be designed to reduce the magnitude of the moment.
The wheel rolling bearing unit of the present invention has been made after the above examination.
[0014]
[Means for Solving the Problems]
The wheel rolling bearing unit of the present invention has a first mounting flange for supporting the suspension device on the outer peripheral surface and a double row outer ring raceway on the inner peripheral surface, respectively, as in the conventional structure described above. A member corresponding to the outer ring that does not rotate during use, a second mounting flange for supporting the wheel near the outer end of the outer peripheral surface, a double-row inner ring raceway in the middle, and an inner end, etc. An inner ring equivalent member that rotates as a housing part serving as an outer ring of the speed joint, and a plurality of rolling elements provided in a freely rotatable manner between each outer ring raceway and each inner ring raceway. Of these, the inner ring equivalent member is formed by combining the first inner ring member and the second inner ring member, and the first inner ring member of the second ring is attached to the outer end portion of the outer peripheral surface. A flange is formed in a cylindrical shape in which one inner ring raceway of the above-mentioned double row inner ring raceways is provided on the inner end portion, and a female spline portion is provided in the middle portion of the inner peripheral surface, and the inner end portion is also provided. The inner cylindrical surface portion having a diameter larger than that of the female spline portion is provided concentrically with each other, and the second inner ring member has an outer end portion that does not rattle the first inner ring member. As a fitting support part for fitting and fixing, the other inner ring raceway of the double row inner ring raceways is provided on the outer peripheral surface of the intermediate part, the inner end part is used as the housing part, and the outer periphery of the fitting support part A male spline portion that engages with the female spline portion on the surface; An outer side cylindrical surface portion to be fitted with the side cylindrical surface portion and the interference, is obtained by forming concentrically with each other.
Especially for the wheel of the present invention Rolling In the bearing unit, the other end edge of the fitting portion between the inner side and outer side cylindrical surface portions is located on the other end side with respect to the axial center position between the two rows of rolling element rows. The center of the contact point of the tire that constitutes the wheel supported by the second mounting flange and the center of gravity of the radial load applied from the road surface to the tread surface exists in the contact portion between the tire tread surface and the road surface. The vertical line that passes through the part between the rolling elements in the double row. And in this part It is located on one end side with respect to the axial center position.
[0015]
[Action]
According to the rolling bearing unit for a wheel of the present invention configured as described above, the moment applied to the fitting portion between the inner and outer cylindrical surface portions can be sufficiently reduced. For this reason, it is possible to sufficiently ensure the durability of the fitting portion and prevent the bending rigidity of the inner ring equivalent member from being lowered.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first example of an embodiment of the present invention. The feature of the present invention is that the inner side and the outer side cylindrical surface portions 10 and 16 are fitted with each other, the vertical line α passing through the center of the ground contact point of the tire constituting the wheel, and provided in multiple rows. This is because the positional relationship between the rolling elements 19 and 19 and the axial center position thereof is regulated. Since the structure and operation of other parts are the same as in the case of the conventional structure described above, the description of the overlapping parts will be omitted or simplified. Hereinafter, the characteristic part of the present invention and parts different from the conventional structure will be mainly described. explain.
[0017]
The second mounting flange 7 formed on the outer peripheral surface of the first inner ring member 4a on the outer end portion (left side portion in FIG. 1) constitutes a wheel 29 constituting a vehicle wheel and a disc brake as a braking device. The rotor 30 is supported and fixed by a plurality of studs 31 and nuts 32. A tire (not shown) is assembled to the outer diameter side portion of the wheel 29. In the case of the present invention, the vertical line α passing through the center of the ground contact point of the tire is present in the portion between the double row rolling element rows (the portion between the center points of the rolling elements 19 and 19 in each row). However, the dimension of each part of the rolling bearing unit for a wheel is regulated so that it is located on the outer side in the axial direction (left side in FIG. 1) than the central position in the axial direction (vertical line β). At the same time, the inner end edge (right end edge in FIG. 1) of the fitting portion 37 is positioned on the inner side in the axial direction (right side in FIG. 1) than the vertical line β. By adopting such a configuration, the moment applied to the fitting portion 37 is reduced, and the durability of the fitting portion 37 is sufficiently ensured. In the illustrated example, both the vertical lines α and β pass through the fitting portion 37. The reason why the moment applied to the fitting portion 37 can be reduced by adopting the above-described configuration will be described later.
[0018]
Further, as described above, in order to position the inner end edge of the fitting portion 37 axially inward from the vertical line β, in the present example, the entire fitting portion 37 is axially inward. The inner end edge of the fitting portion 37 (that is, both the inner and outer cylindrical surface portions 10 and 16) is extended inward in the axial direction so that the entire fitting portion 37 is not moved. The axial dimension of is increased. In the illustrated example, the inner end surface of the first inner ring member 4a and the second inner ring member are present at the inner end edge portion of the fitting portion 37 in order to sufficiently extend the inner end edge of the fitting portion 37. The contact portion with the step portion 33 formed on the outer peripheral surface of the intermediate portion 5a is disposed close to the vicinity of the inner side (right side in FIG. 1) of the rolling element row. Thus, in this example, since the axial dimension of the fitting portion 37 is increased, the support strength of the first inner ring member 4a with respect to the second inner ring member 5a, and the fitting portion The load capacity for the moment load of 37 can be sufficiently increased. As described above, as a means for increasing the axial dimension of the fitting portion 37, it is also effective to extend the outer end edge of the fitting portion 37 outward in the axial direction. In this case, even if the engagement between the female spline portion 9 and the male spline portion 15 at the time of assembly is taken into consideration, the outer end edge of the fitting portion 37 is located outside (the left side in FIG. ) Is further extended outward in the axial direction than the rolling element row in order to sufficiently secure the axial dimension of the fitting portion 37.
[0019]
In the case of this example, the inner end surface of the first inner ring member 4a and the stepped portion 33 are brought into contact with each other in order to connect the first and second inner ring members 4a and 5a to form the hub 6a. In the state, the size of each part is regulated so that an appropriate preload is applied to each rolling element 19, 19. In the case of this example, the fitting strength of the fitting portion 37 is sufficiently ensured by increasing the size of the fastening allowance given to the fitting portion 37 to about 15 to 40 μm. Further, the surfaces of both the inner side and outer side cylindrical surface portions 10 and 16 are subjected to hardening treatment by induction hardening or the like. Thereby, both the cylindrical surface portions 10 and 16 are provided with a strength capable of withstanding a large contact surface pressure applied to the fitting portion 37.
[0020]
In the case of the wheel rolling bearing unit of the present example configured as described above, the moment applied to the fitting portion 37 can be reduced. The reason for this will be described below with reference to FIG. The reaction force N applied from the center of the tire contact point is the operating point O of the double row rolling element row. ₁ , O ₂ Radial load F applied to _R1 , F _R2 As distributed. When the reaction force N (the vector on the vertical line α) is shifted between the rolling element rows in the double row and axially outward from the axial center position of the intermediate portion as in the present invention. Includes the action point O of the inner rolling element row. ₂ Radial load F applied to _R2 Is the action point O of the outer rolling element row ₁ Radial load F applied to _R1 Smaller than. For this reason, the point of action O of the inner rolling element row ₂ Radial load F applied to _R2 Based on the moment M acting on the fitting portion 37 ₂ (= F _R2 ・ S ₂ ) Can be reduced.
[0021]
Furthermore, in the case of this example, the inner end edge of the fitting portion 37 is positioned inward in the axial direction from the axial center position of the portion between the two rows of rolling element rows. For this reason, the center point O in the axial direction of the fitting portion 37. ₃₇ Is the action point O of the inner rolling element row ₂ Both of these points O ₃₇ , O ₂ Spacing S in the axial direction between each other ₂ Becomes smaller. Therefore, again, the radial load F _R2 Based on the moment M acting on the fitting portion 37 ₂ (= F _R2 ・ S ₂ ) Can be reduced. On the other hand, as described in the above-mentioned [Problem to be solved by the present invention], the fitting portion 37 has the reaction force N and the action point O of the outer rolling element row. ₁ Radial load F acting on _R1 Moment M based on ₁ 'Is added. In this case, from the balance condition, both the moments M ₁ ', M ₂ Are equal in size. Therefore, the moment M ₂ The moment M ₁ ′ Can also be reduced. For this reason, in this example, the moment applied to the fitting portion 37 can be reduced, and the durability of the fitting portion 37 can be sufficiently ensured.
[0022]
In the above description, only the load and moment applied to each part are considered when the vehicle is traveling straight ahead with high traveling frequency. On the other hand, when the automobile turns, as shown in FIG. 2, centrifugal force F is applied to the automobile 38, and the tires 39a and 39b constituting the wheels have a radial load R as a reaction force from the road surface. ₁ , R ₂ Besides, thrust load A ₁ , A ₂ Will be added. In addition, since the centrifugal force F as described above acts on the center of gravity of the automobile 38, the vehicle body rolls to move the load. However, it becomes higher than the contact pressure of the tire 39a on the inner peripheral side (right side in FIG. 2). For this reason, the reaction force R from the road surface applied to the tire 39b on the outer peripheral side in the turning direction ₂ , A ₂ Is the reaction force R from the road surface applied to the tire 39a on the inner periphery side in the turning direction. ₁ , A ₁ Bigger than.
[0023]
Therefore, next, as described above, a large reaction force R from the road surface ₂ , A ₂ Considering the wheel rolling bearing unit for supporting the tire 39b on the outer periphery side in the turning direction. The wheel rolling bearing unit that supports the tire 39b on the outer periphery side in the turning direction has a thrust load A applied to the tire 39b from the road surface. ₂ On the basis of the moment (when the vertical distance from the center axis of the bearing unit to the ground plane is X, A ₂ • Moment of X magnitude) acts. This thrust load A ₂ Is the action point O of the outer rolling element row (left side in FIG. 5). ₁ Radial load F applied to _R1 The action point O of the inner rolling element row (right side in FIG. 5) is reduced. ₂ Radial load F applied to _R2 Acts in the direction of increasing
[0024]
Therefore, during the turning of the automobile 38, the largest radial load acts on the inner rolling element row constituting the wheel rolling bearing unit that supports the tire 39b on the outer periphery side in the turning direction. For this reason, in the case of the present invention, also from the viewpoint of ensuring the durability of the inner rolling element row, as described above, the vertical line α is arranged axially outward from the vertical line β as described above. Radial load F acting on inner rolling element row _R2 Is actively reduced. When the vertical line α (the reaction force N from the road surface) is shifted axially outward from the vertical line β as in this example, the amount of shift is adjusted to adjust the double row rolling. It is preferable not to cause a large difference in the peeling life of the moving body row. In this case, the amount of deviation between the two vertical lines α and β is the distance between the action points of the outer rolling element row and the inner rolling element row S (S in FIG. 5). ₁ + S ₂ ) Is preferably about 5 to 15% of the distance S between the operating points. For example, in the case of a rolling bearing unit for a wheel for a general passenger car, it is set to about 2 to 6 mm.
[0025]
In the case of this example shown in FIG. 1, the moment applied to the hub 6a is supported by the fitting portion 37 between the inner and outer cylindrical surface portions 10 and 16, and the first inner ring. The contact portion between the inner end surface of the member 4a and the stepped portion 33, and the nut 18 screwed and tightened to the distal end portion of the fitting support portion 11 and the outer peripheral portion near the inner peripheral surface of the first inner ring member 4a. It supports also in the contact part with the provided step part 34. FIG. Therefore, in order to increase the ratio of the moment that can be supported by each of the contact portions, and to prevent a large moment load from being applied to the fitting portion 37, the distance L in the axial direction between the contact portions. And a width dimension H extending in the diameter direction of each contact portion. ₁₈ , H ₃₃ Are preferably made as large as possible.
[0026]
When the present invention is actually carried out, the position of the vertical line α in the axial direction is the offset amount of the wheel 29 supported and fixed to the second mounting flange 7 {the second mounting of the wheel 29 described above. The distance between the mounting surface with respect to the flange 7 and the center line in the width direction of the wheel 29 (a straight line that coincides with the vertical line α when the camber angle is assumed to be 0) varies depending on the size of δ. . Therefore, when the present invention is implemented, the dimensions of the constituent members are regulated in consideration of the offset amount δ and the camber angle of the wheel 29 supported by the second mounting flange 7.
[0027]
Next, FIG. 3 shows a second example of the embodiment of the present invention. In the case of this example, the tip half part of the fitting support part 11a which comprises the 2nd inner ring member 5b is made into the cylindrical part 35, and many male spline grooves which comprise the male spline part 15 are formed in the outer peripheral surface of this cylindrical part 35. The cylindrical portion 35 is formed over the entire length (including the tip portion). In addition, a portion protruding from the outer end (left end in FIG. 2) opening of the female spline portion 9 provided on the inner peripheral surface of the intermediate portion of the first inner ring member 4b at the tip portion of the cylindrical portion 35 is outside the diametrical direction. The caulking portion 36 is formed by plastic deformation. The first inner ring member 4b is sandwiched between the caulking portion 36 and a step portion 33 provided on the outer peripheral surface of the intermediate portion of the second inner ring member 5b, thereby forming the hub 6b.
[0028]
In the case of this example, the female spline portion 9 is subjected to quenching and hardening treatment over the entire length, but the male spline portion 15 has only the portion excluding the tip portion that forms the caulking portion 36. A quench hardening treatment is applied. Thereby, the front-end | tip part of the said cylindrical part 35 can be plastically deformed to a diameter direction outward, and formation of the said crimping | crimped part 36 is made free. In carrying out this example, it is not necessary to form the male spline grooves as far as the tip of the cylindrical portion 35, which is the portion where the caulking portion 36 is formed. However, in the case of the illustrated example, each male spline groove is formed up to the end edge of the cylindrical portion 35 in order to facilitate the processing of each male spline groove. In the case of this example configured as described above, as compared with the first example described above, since the nut 18 (see FIG. 1) is not used, weight reduction and cost reduction associated with a reduction in the number of parts can be achieved. Other configurations and operations are the same as those of the first example described above.
[0029]
【The invention's effect】
Since the wheel rolling bearing unit of the present invention is configured and operates as described above, the durability of the fitting portion between the inner cylindrical surface portion and the outer cylindrical surface portion is sufficiently ensured, and the rigidity of the hub is ensured. Can be prevented from decreasing. As a result, the durability of the wheel rolling bearing unit can be improved.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a force applied when the automobile turns.
FIG. 3 is a partial sectional view showing a second example of the embodiment of the present invention.
FIG. 4 is a partial cross-sectional view showing an example of a conventional structure.
FIG. 5 is a schematic diagram showing a load acting on a hub.
[Explanation of symbols]
1 outer ring
2 First mounting flange
3 Outer ring raceway
4, 4a, 4b First inner ring member
5, 5a, 5b Second inner ring member
6, 6a, 6b hub
7 Second mounting flange
8 First inner ring raceway
9 Female spline section
10 Inner cylindrical surface
11, 11a Fitting support part
12 Constant velocity joint
13 Housing part
14 Second inner ring raceway
15 Male spline section
16 Outer cylindrical surface
17 Male thread
18 nuts
19 Rolling elements
20a, 20b cover
21a, 21b Seal ring
22 Bulkhead
23 inner ring
24 Cage
25 balls
26 Inner engagement groove
27 Outer engagement groove
28 pockets
29 wheels
30 rotor
31 Stud
32 nuts
33 steps
34 steps
35 Cylindrical part
36 Caulking part
37 Fitting part
38 cars
39a, 39b tires

Claims

A first mounting flange for supporting the suspension device on the outer peripheral surface, a double-row outer ring raceway on the inner peripheral surface, and an outer ring equivalent member that does not rotate during use, and a wheel near one end of the outer peripheral surface A second mounting flange for supporting the inner ring, a double row inner ring raceway is provided in the middle part, and the other end part is a housing part that becomes the outer ring of the constant velocity joint; And a plurality of rolling elements provided between the outer ring raceways and the inner ring raceways. The inner ring equivalent members include a first inner ring member and a second inner ring member. The first inner ring member is formed by combining the second mounting flange near one end of the outer peripheral surface, and one inner ring raceway among the double row inner ring raceways similarly at the other end. Are formed in the provided cylindrical shape, and the inner A female spline portion is provided in the middle portion of the surface, and an inner cylindrical surface portion having a diameter larger than that of the female spline portion is provided concentrically with each other, and the second inner ring member has one end portion. Is a fitting support portion for externally fixing the first inner ring member without rattling, the other inner ring raceway of the double row inner ring raceways is provided on the outer peripheral surface of the intermediate portion, and the other end portion is A male spline portion that engages with the female spline portion and an outer cylindrical surface portion that engages with the inner cylindrical surface portion are concentric with each other on the outer peripheral surface of the fitting support portion. in the bearing unit rolling for at which a wheel that is formed on, the inner side, the other edge of the fitting portion between the outer side two cylindrical surface portion, axially between portions of the rolling element row between the double row Located on the other end side than the center position and supported by the second mounting flange And the vertical line passing through the ground contact point center of the tire which constitutes the wheel, the wheel, characterized in between portions of the rolling element row between the double row, it was positioned on one end side than the axial center position therebetween portion use rolling bearing unit.