JP3932630B2

JP3932630B2 - Rolling bearing unit for wheels

Info

Publication number: JP3932630B2
Application number: JP31032197A
Authority: JP
Inventors: 康允水越; 喜章小野瀬; 直樹満江; 英男大内
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 1997-09-16
Filing date: 1997-11-12
Publication date: 2007-06-20
Anticipated expiration: 2017-11-12
Also published as: JPH11151904A

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）の前輪、ＦＲ車（前置エンジン後輪駆動車）及びＲＲ車（後置エンジン後輪駆動車）の後輪、４ＷＤ車（四輪駆動車）の全輪等の駆動輪を、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、独立懸架式サスペンションにより支持した駆動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、車輪とデファレンシャルギヤとの相対変位に拘らず、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。特に、操舵輪と駆動軸とが一致する場合に、重要性が大きい。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、実開昭６１−１１３１０３号公報に記載されたものが知られている。
【０００３】
図１２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は、外周面にこの懸架装置に支持する為の外向フランジ状の取付部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の内側には、ハブ４と第一、第二の内輪５、６とを設けている。このうちのハブ４の外周面の外端（外とは、自動車への組み付け状態で幅方向外寄りとなる側を言い、図１２及び後述する図１、３〜１１の左側となる。反対に幅方向中央寄りとなる側を内と言い、図１２及び図１、３〜１１の右側となる。）寄り部分には、上記ハブ４に車輪を支持固定する為のフランジ７を、このハブ４と一体に形成している。このフランジ７には、円周方向に亙り等間隔に複数本（通常４〜６本）のスタッド８を、それぞれ軸方向に圧入固定しており、組み付け時にはこれら複数本のスタッド８を利用して、上記フランジ７に上記車輪を支持固定する。又、上記ハブ４の内端側部分は、等速ジョイント９の外輪となる、ハウジング部１０としている。
【０００４】
又、上記ハブ４の中間部に、上記第一、第二の内輪５、６を外嵌固定している。これら第一、第二の内輪５、６の外周面には、それぞれ第一、第二の内輪軌道１１、１２を形成している。そして、上記各外輪軌道３、３と上記第一、第二の内輪軌道１１、１２との間に、それぞれ複数個ずつの転動体１３、１３を設ける事により、上記外輪１の内側に上記ハブ４及び第一、第二の内輪５、６を、回転自在に支持している。尚、上記各転動体１３、１３を設けた環状空間の両端開口部、即ち、上記外輪１の両端部内周面と上記第一の内輪５の外端部外周面及び上記第二の内輪６の内端部外周面との間の隙間は、それぞれシールリング１４、１４により塞いでいる。又、上記ハブ４の外周面でこのハブ４の中間部内端寄り部分には、全周に亙り係止凹溝１５を形成すると共に、この係止凹溝１５に、欠円環状の止め輪１６を係止している。そして、この止め輪１６と、上記フランジ７の基端内側部分に形成した段部１７との間で、上記第一、第二の内輪５、６を、軸方向両側から挟持している。この状態で上記止め輪１６は、上記第一、第二の内輪５、６が、上記ハブ４の軸方向内端側にずれ動くのを防止する。
【０００５】
又、上記ハウジング部１０の内端部外周面には、ゴム或は合成樹脂等の弾性材により蛇腹状に形成したブーツ１８の外端部を係止している。即ち、このブーツ１８の外端部で上記ハウジング部１０の内端部に外嵌した円筒状部分を、抑えバンド１９により抑え付けている。そして、上記ブーツ１８の外端部内周面と前記ハウジング部１０の内端部外周面に形成した係合溝２０とを、全周に亙り係合させている。又、上記ブーツ１８の他端部は、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駆動軸２１の中間部外周面（図示せず）に、密に結合している。この様なブーツ１８は、上記ハウジング部１０の内側空間と外部とを遮断し、この内側空間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、この内側空間に雨水、塵芥等の異物が侵入する事を防止する。
【０００６】
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、取付部２により外輪１を懸架装置に支持固定し、フランジ７により、駆動輪をハブ４に支持固定する。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、上記駆動軸２１の先端部を、前記等速ジョイント９を構成する内輪２２の内径側にスプライン係合させる。自動車の走行時には、この内輪２２の回転を、複数の玉２３を介して上記ハブ４に伝達し、上記駆動輪を回転駆動する。
【０００７】
【発明が解決しようとする課題】
図１２に示した従来構造の場合、車輪用転がり軸受ユニットの小型・軽量化を図る事が難しい。この理由は、次の通りである。即ち、上記従来構造の場合、スタッド８と第一の内輪５との干渉を防止する為、このスタッド８を固定する為のフランジ７の形成位置を軸方向外方にずらせている。この様に、このフランジ７の形成位置を軸方向外方にずらせた分だけ、ハブ４の軸方向寸法が大きくなり、車輪用転がり軸受ユニットの小型・軽量化を図れなくなる。
【０００８】
上記フランジ７の外径を大きくし、上記スタッド８の固定位置を直径方向外方にずらせて、これら各スタッド８の頭部２４と外輪１の外端部との干渉防止を図れば、上記軸方向寸法を小さくする事が可能ではある。但し、この場合には、上記フランジ７に支持固定する複数本のスタッド８のピッチ円直径（p.c.d.）が必要以上に大きくなり、やはり車輪用転がり軸受ユニットの小型・軽量化を図れなくなる。車輪用転がり軸受ユニットの重量の増大は、自動車のばね下荷重の増大に繋がり、自動車の乗り心地性能及び燃費性能の悪化に結び付く為、好ましくない。
本発明は、この様な事情に鑑みて、軸方向寸法並びに車輪支持固定用のスタッド８のp.c.d.を何れも小さくする事ができ、小型・軽量化が可能な車輪用転がり軸受ユニットを実現すべく考えたものである。
【０００９】
【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、前述の図１２に示した車輪用転がり軸受ユニットと同様に、外周面に懸架装置に支持する為の取付部を、内周面に複列の外輪軌道を、それぞれ有する外輪と、外周面の一端寄り部分で上記外輪から軸方向に突出した部分に車輪を支持固定する為のフランジを形成し、同じく中間部に第一の内輪軌道を設けると共に、他端側部分を等速ジョイントの外輪となるハウジング部としたハブと、外周面に第二の内輪軌道を形成して、上記ハブの中間部のうち上記第一の内輪軌道を形成した部分よりも他端寄り部分に外嵌固定した内輪と、上記複列の外輪軌道と上記第一、第二の内輪軌道との間にそれぞれ複数個ずつ転動自在に設ける事により、上記外輪の内側に上記ハブ及び内輪を回転自在に支持する複数個の転動体と、この外輪の一端部内周面とこのハブの中間部外周面との間の環状隙間を塞ぐシールリングとを備える。
【００１０】
特に、本発明の車輪用転がり軸受ユニットに於いては、上記フランジと上記ハウジング部とが上記ハブに一体に形成されており、上記第一の内輪軌道をこのハブの中間部外周面に直接形成すると共に、このハブの中間部外周面のうち、この第一の内輪軌道と上記フランジの基端部内側面との間部分で、周囲に上記シールリングが配設された部分の外径を、上記内輪を外嵌固定した部分の外径よりも大きくしており、上記第一の内輪軌道に関する転動体列を構成する複数個の転動体のピッチ円直径を、上記第二の内輪軌道に関する転動体列を構成する複数個の転動体のピッチ円直径よりも小さくしている。
【００１１】
【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の場合には、車輪を支持固定する為のスタッドを固定するフランジ側の転動体のピッチ円直径が小さい分、ハブの軸方向寸法を大きくする事なくフランジの外径を小さくできる。従って、このフランジの外径を小さくする分、車輪用転がり軸受ユニットの小型・軽量化を図れる。
【００１２】
【発明の実施の形態】
図１〜２は、本発明の実施の形態の第１例を示している。尚、本発明の車輪用転がり軸受ユニットの特徴は、小型・軽量化を図るべく、この車輪用転がり軸受ユニットを構成する転がり軸受部の構造を工夫した点にある。その他の部分の構造及び作用は、前述の図１２に示した従来構造とほぼ同様であるから、同等部分には同一符号を付して重複する説明を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。
【００１３】
本発明の車輪用転がり軸受ユニットの場合、第一の内輪軌道１１は、ハブ４ａの中間部外周面に直接形成している。又、このハブ４ａの中間部のうち、上記第一の内輪軌道１１を形成した部分よりも内端寄り部分に、外周面に第二の内輪軌道１２を形成した内輪６を外嵌している。そして、上述の様に、上記第一の内輪軌道１１を上記ハブ４ａの外周面に直接形成する事により、この第一の内輪軌道１１の直径を、上記内輪６の外周面に形成した第二の内輪軌道１２の直径よりも小さくしている。又、この様に第一の内輪軌道１１の直径を第二の内輪軌道１２の直径よりも小さくした事に伴い、上記第一の内輪軌道１１と対向する外側（図１の左側）の外輪軌道３ａの直径を、内側（図１の右側）の外輪軌道３ｂの直径よりも小さくしている。更に、この外側の外輪軌道３ａを形成した、外輪１の外半部の外径を、上記内側の外輪軌道３ｂを形成した部分である、上記外輪１の内半部の外径よりも小さくしている。
【００１４】
即ち、上記第一の内輪軌道１１を上記ハブ４ａの中間部外周面に直接形成している為、この第一の内輪軌道１１の直径を、前述の図１２に示した従来構造の如く、第一の内輪軌道１１をハブ４の外周面に、第一の内輪５を介して設けた場合に比べて小さくできる。従って、複列に設けた転動体列のうち、外側（図１の左側）の転動体列を構成する各転動体１３、１３のピッチ円直径は、内側（図１の右側）の転動体列を構成する各転動体１３、１３のピッチ円直径よりも小さい。又、図示の例では、この様に第一の内輪軌道１１及び外側の外輪軌道３ａの直径を小さくした事に伴い、これら第一の内輪軌道１１と外側の外輪軌道３ａとの間に設ける転動体１３、１３の数を、上記第二の内輪軌道１２と内側の外輪軌道３ｂとの間に設ける転動体１３、１３の数よりも少なくしている。
【００１５】
又、上記ハブ４ａのフランジ７に設ける複数のスタッド８のピッチ円直径は、上述の様に外輪１の外半部の外径を、同じく内半部の外径よりも小さくした分だけ（上記各スタッド８の頭部２４が上記外輪１の外端部外周面と干渉しない程度に）小さくしている。尚、上記ハブ４ａの外周面のうちで、上記第一の内輪軌道１１を形成した部分よりも軸方向内方に存在する部分の直径は、この第一の内輪軌道１１に対応する転動体１３、１３の内接円の直径よりも小さくしている。この理由は、車輪用転がり軸受ユニットの組み立て時に、外輪１の外端部内周面に形成した外輪軌道３ａの内径側に複数の転動体１３、１３を組み付けると共に、上記外輪１の外端部内周面にシールリング１４を内嵌固定した状態で、この外輪１の内径側に上記ハブ４ａを挿入自在とする為である。又、上記ハブ４ａの中間部外周面で、上記第一の内輪軌道１１と上記内輪６を外嵌した部分との間部分には、全周に亙り凹溝状の肉盗み部２５を形成して、上記ハブ４ａの軽量化を図っている。
【００１６】
又、上記ハブ４ａに外嵌した内輪６が軸方向内端側にずれ動くのを防止して、上記各外輪軌道３ａ、３ｂと上記第一、第二の内輪軌道１１、１２との間にそれぞれ複数個ずつ転動自在に設けた、上記各転動体１３、１３に付与した予圧を適正値に保持すべく、上記ハブ４ａの外周面内端寄り部に全周に亙り形成した係止凹溝１５に、止め輪１６ａを係止している。この止め輪１６ａは、図２に示す様な、１対の半円弧状の止め輪素子２６、２６により構成している。この様な止め輪素子２６、２６は、上記各転動体１３、１３に適正な予圧を付与すべく、上記内輪６を上記ハブ４ａに対して軸方向外方に押圧しつつ、それぞれの内周縁部を上記係止凹溝１５に係合させる。上記内輪６を軸方向外方に押圧している力を解除した状態でも上記各転動体１３、１３に適正な予圧を付与したままにすべく、上記各止め輪素子２６、２６として、適切な厚さ寸法を有するものを選択使用する。即ち、上記各止め輪素子２６、２６として、厚さ寸法が僅かずつ異なるものを複数種類用意し、上記係止凹溝１５の溝幅等、転がり軸受ユニットの構成各部材の寸法との関係で適切な厚さ寸法を有する止め輪素子２６、２６を選択し、上記係止凹溝１５に係合させる。従って、これら各止め輪素子２６、２６を係止凹溝１５に係止すれば、上記押圧している力を解除しても、上記内輪６が軸方向内端側にずれ動くのを防止して、上記各転動体１３、１３に適切な予圧を付与したままに保持できる。
【００１７】
又、上記１対の止め輪素子２６、２６が直径方向外方に変位し、これら各止め輪素子２６、２６が上記係止凹溝１５から不用意に抜け落ちる事を防止すべく、これら１対の止め輪素子２６、２６の周囲に、ブーツ１８ａの一部を配置している。このブーツ１８ａは、上記ハブ４ａの内端部分に設けたハウジング部１０により構成する等速ジョイント内に、雨水、塵芥等の異物が入り込むのを防止する為のもので、ゴム、合成樹脂等の弾性材により一体成形し、中間部を蛇腹状に、両端部を円筒状に、それぞれ形成している。この様なブーツ１８ａの外端部は、上記ハブ４ａの内端部に外嵌し、抑えバンド１９によりこのハブ４ａの内端部外周面に抑え付けて、上記ブーツ１８ａの外端部内周面とハウジング部１０の内端部外周面に形成した係合溝２０とを、全周に亙り係合させている。
【００１８】
上記ブーツ１８ａの外端縁部で上記抑えバンド１９よりも軸方向外方に突出した部分は断面クランク形に形成して、全周に亙る抑え部２７を構成している。この抑え部２７は、上記ハブ４ａの内端部に外嵌する小径円筒部２８と、この小径円筒部２８の外端縁から直径方向外方に折れ曲がった円輪部２９と、この円輪部２９の外周縁から軸方向外方に折れ曲がった大径円筒部３０とから成る。そして、このうちの円輪部２９の外側面を上記止め輪１６ａの内側面に突き当てると共に、上記大径円筒部３０を上記止め輪１６ａに外嵌している。
【００１９】
上述の様に構成する本例の車輪用転がり軸受ユニットにより、車輪を懸架装置に対して回転自在に支持する作用は、前述した従来の車輪用転がり軸受ユニットの場合と同様である。特に、本例の場合には、外側の転動体列を構成する各転動体１３、１３のピッチ円直径を小さくする事により、外輪１の外半部の外径を小さくできる。そして、この外輪１の外半部の外径を小さくした分だけ、ハブ４ａのフランジ７に設ける複数のスタッド８のピッチ円直径を小さくできる。従って、前述した従来構造の様に、上記ハブ４ａの軸方向寸法を大きくする事なく、上記スタッド８を支持固定する上記フランジ７の外径を小さくして、車輪用転がり軸受ユニットの小型・軽量化を図れる。
【００２０】
又、外側の転動体列を構成する各転動体１３、１３のピッチ円直径を内側の転動体列を構成する各転動体１３、１３のピッチ円直径よりも小さくする事で、外側の転動体列部分の基本動定格荷重が内側の転動体列部分の基本動定格荷重よりも小さくなる。従って、両列に加わる荷重が同じであれば、外側の転動体列部分の寿命が内側の転動体列部分の寿命よりも短くなる。これに対して、一般的な自動車では、外側の転動体列部分に加わる荷重は内側の転動体列部分に加わる荷重よりも小さい。この為、上記両列部分の寿命をほぼ同じにする設計が容易になって、無駄のない設計が可能になる。尚、図示の例では、転動体１３、１３として玉を使用しているが、重量の嵩む自動車用の転がり軸受ユニットの場合には、転動体としてテーパころを使用する場合もある。本発明は、勿論、この様に転動体としてテーパころを使用する転がり軸受ユニットにも適用可能である。
【００２１】
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、係止凹溝１５に係止した止め輪１６ａを構成する１対の止め輪素子２６、２６が、この係止凹溝１５内から抜け落ちる事をより確実に防止すべく、ブーツ１８ａの外端部で上記１対の止め輪素子２６、２６の周囲を覆う部分の剛性を向上させている。この為に本例の場合には、上記ブーツ１８ａの外端部に、断面クランク形で全体を欠円環状に形成した金属板３１を外嵌している。懸架装置への組み付け状態でこの金属板３１は、抑えバンド１９によって、上記ブーツ１８ａの外端部と共にハブ４ａの内端部外周面に抑え付ける。この状態で、上記金属板３１は、弾性材製の上記ブーツ１８ａの外端部に形成した抑え部２７が直径方向外方に変形する事を防止する。従って、この抑え部２７の大径円筒部３０が、上記１対の止め輪素子２６、２６が直径方向外方に変位するのを確実に防止する。
【００２２】
又、上記ハブ４ａに外嵌した内輪６の表面のうち、このハブ４ａの外周面に対向する内周面と、上記１対の止め輪素子２６、２６の外側面に対向する内側面とには、セラミック、合成樹脂等の断熱材製の断熱層３２を形成している。この断熱層３２は、車輪用転がり軸受ユニットの使用時に、等速ジョイント部分で発生した熱が、上記内輪６に対向するハブ４ａ及び止め輪１６ａを介して、この内輪６に伝わる事を防止する。この為、各転動体１３、１３を設置した環状空間３３の内端開口を塞ぐシールリング１４の温度上昇を抑える事ができる。この結果、このシールリング１４を構成し、上記内輪６の外周面に外嵌固定したスリンガ３４と摺接する弾性材製のシールリップ３５として、特に優れた耐熱性を有する高価な材料を使用する必要がなくなる。具体的には上記シールリップ３５を、ニトリルブタジエンゴム（ＮＢＲ）、Ｈ−ニトリルブタジエンゴム（Ｈ−ＮＢＲ）等の、比較的安価な材料により造っても、十分な耐久性を得られる。
【００２３】
尚、上記シールリップ３５が摺接するスリンガ３４の温度上昇を抑える為には、このスリンガ３４と上記ハブ４ａとの間の何れかの部分に、断熱層を介在させれば良い。例えばこの断熱層を、上記スリンガ３４の内周面に形成したり、上記ハブ４ａの中間部外周面及び上記止め輪１６ａの外側面に形成する事もできる。更には、熱の伝達方向に関して直列に存在する複数個所に断熱層を介在させる事もできる。その他の構成及び作用は、前述の図１〜２に示した第１例の場合と同様であるから、同等部分には同一符号を付して、重複する説明を省略する。
【００２４】
次に、図４は、本発明の実施の形態の第３例を示している。本例の場合、車輪を懸架装置に回転自在に支持すると共に、この車輪の回転速度を検出する機能を有する、回転速度検出装置付車輪用転がり軸受ユニットに、本発明を適用している。本例の場合には、係止凹溝１５に係止した止め輪１６ａを構成する１対の止め輪素子２６、２６に、円筒状のトーンホイール３６を、締り嵌めにより外嵌固定している。このトーンホイール３６は、ＳＰＣＣの如き軟鋼板等、磁性金属板を円筒状に形成して成り、軸方向（図４の左右方向）中間部には、それぞれが軸方向に長いスリット状の透孔３７、３７を、円周方向に亙り等間隔で、多数形成している。この様なトーンホイール３６には、上記多数の透孔３７、３７と円周方向に隣り合う透孔３７、３７同士の間に存在する柱部とが、円周方向に亙って交互に存在する。従って上記トーンホイール３６の外周面の磁気特性は、円周方向に亙り交互に且つ等間隔で変化する。
【００２５】
上記止め輪１６ａを構成する１対の止め輪素子２６、２６は、この様なトーンホイール３６でそれぞれの外周面を抑え付けられる事により、直径方向外方への変位を阻止され、上記係止凹溝１５から抜け出る事を防止される。尚、上記トーンホイール３６の外周面には、懸架装置を構成するナックル等、図示しない固定部分に支持固定したセンサ３８の先端部に設けた検出面を、微小隙間を介して対向させ、ハブ４ａと共に回転する車輪の回転速度を検出する為の回転速度検出装置を構成する。その他の構成及び作用は、前述の図１〜２に示した第１例の場合と同様であるから、同等部分には同一符号を付して、重複する説明を省略する。
【００２６】
次に、図５は、本発明の実施の形態の第４例を示している。本例の場合も、回転速度検出装置付車輪用転がり軸受ユニットに本発明を適用している。本例の場合、係止凹溝１５に係止した止め輪１６ａを構成する１対の止め輪素子２６、２６に、エンコーダ３９を外嵌する事により、これら両止め輪素子２６、２６が直径方向外方に変位する事を阻止している。上記エンコーダ３９は、磁性金属板を曲げ形成する事により断面Ｌ字形で全体を円環状に形成した支持環４０と、円輪状の永久磁石であるエンコーダ本体４１とから成る。このうちの支持環４０は、円筒部４２と、この円筒部４２の外端部から直径方向外方に折れ曲がった円輪部４３とから成る。上記止め輪１６ａには、このうちの円筒部４２を、締り嵌めで外嵌する事により、上記エンコーダ３９を上記止め輪１６ａの周囲に支持固定すると共に、この止め輪１６ａが上記係止凹溝１５から外れない様にしている。
【００２７】
一方、上記エンコーダ本体４１は、上記支持環４０の円輪部４３の内側面に、焼き付け、接着、自身の磁気吸引力等により、全周に亙って添着固定している。例えば、ゴム中にフェライトの粉末を混入して成るゴム磁石である、上記エンコーダ本体４１は、軸方向（図５の左右方向）に亙り着磁している。着磁方向は、円周方向に亙って交互に、且つ、等間隔で変化させている。従って、上記エンコーダ本体４１の内側面には、Ｎ極とＳ極とが交互に、且つ、等間隔で配置されている。この様なエンコーダ本体４１の内側面には、図示しない固定部分に支持固定したセンサ３８ａの先端部に設けた検出面を、微小隙間を介してアキシャル方向に亙り対向させ、ハブ４ｂと共に回転する車輪の回転速度を検出する為の回転速度検出装置を構成する。
【００２８】
尚、上記センサ３８ａの出力を確保する為には、上記エンコーダ本体４１の直径方向に亙る幅寸法Ｗ₄₁を大きくし、このエンコーダ本体４１から出る磁束の量を多くする事が好ましい。本例の場合には、上記エンコーダ３９を、内輪６よりも小径の止め輪１６ａに外嵌固定しているので、上記幅寸法Ｗ₄₁の確保が容易である。即ち、円輪状のエンコーダ本体４１を支持する部分としては、上記内輪６の内端部に外嵌固定したスリンガ３４の内側面が考えられるが、本例の構造によれば、このスリンガ３４にエンコーダ本体を設けた場合に比べて、上記幅寸法Ｗ₄₁を大きくできる。
【００２９】
又、本例の場合には、車輪用転がり軸受ユニットの軽量化を図るべく、ハブ４ｂを、軸方向両端面同士を連通させる、中空円筒状に形成している。そして、上記ハブ４ｂの中間部内周面に塞ぎ板４４を内嵌固定して、このハブ４ｂの外端開口部と内端開口部との連通を遮断している。上記塞ぎ板４４は、外部に存在する雨水や塵芥等の異物が、上記ハブ４ｂの内端部に設けたハウジング部１０を含んで構成する等速ジョイント内に入り込むのを防止すると共に、この等速ジョイント内のグリースが外部に漏洩する事を防止する。尚、このグリースが必要部分から移動する事を有効に防止する為、上記塞ぎ板４４は、上記ハウジング１０寄り部分に設けている。この様な塞ぎ板４４は、板厚が１mm程度若しくはそれ以下の鋼板をプレス加工する事により造れる為、前述した第１〜３例の様に、鍛造品であるハブ４ａの中間部内周面に隔壁４５（図１、３、４）を一体に形成する場合に比べて、ハブ４ｂの軽量化を図れる。
【００３０】
更に、本例の場合には、フランジ７に支持固定する複数本のスタッド８の頭部２４の内接円の直径Ｒ₂₄を、外輪１の外端部の外径Ｄ₁ よりも小さく（Ｒ₂₄＜Ｄ₁ ）して、上記スタッド８のピッチ円直径を可及的に小さくしている。この場合でも、上記頭部２４と、上記外輪１の外端部に内嵌固定したシールリング１４のシールリップ３５ａとが干渉しない様にする。本発明の車輪用転がり軸受ユニットの場合には、上記外輪１の外端部の直径が小さくなっており、上記シールリップ３５ａの直径も小さくなっている為、上記スタッド８の頭部２４の内接円の直径Ｒ₂₄を、従来構造に比べて小さくできる。その他の構成及び作用は、前述の図４に示した第３例の場合と同様であるから、同等部分には同一符号を付して、重複する説明を省略する。尚、図示は省略したが、複数本のスタッドのピッチ円直径を更に小さくする為に、これら各スタッドの頭部の外周縁形状を円形とせず、Ｄ字形の如き欠円形状とする事もできる。この場合、上記シールリップ３５ａに近い内径側に、上記頭部の切り欠き部分（Ｄ字形の直線部分）を位置させて、上記各スタッドを上記フランジ７の内径側に寄せて設けた場合でも、上記頭部と上記シールリップ３５ａとが干渉しない様にする。
【００３１】
次に、図６は、本発明の実施の形態の第５例を示している。本例の場合も、回転速度検出装置付車輪用転がり軸受ユニットに本発明を適用している。但し、本例の場合には、係止凹溝１５に係止した止め輪１６ａを構成する１対の止め輪素子２６、２６の周囲に、ブーツ１８の外端部を外嵌する為の間座４６の一部を配置する事により、これら両止め輪素子２６、２６が直径方向外方に変位する事を阻止している。
【００３２】
上記間座４６は、焼結金属等により一体成形したもので、断面形状をｈ字形とし、全体を円環状に形成している。即ち、上記間座４６は、内径側円筒部４７と、外径側円筒部４８と、これら内径側円筒部４７の外端縁と外径側円筒部４８の中間部内周面とを連結する連結部４９とから成る。このうちの内径側円筒部４７はハブ４ａの内端部に、十分に大きな引き抜き力（例えば１００kgf 以上）を確保すべく、十分に大きな締り嵌めにより外嵌固定している。又、上記外径側円筒部４８の中間部外周面には、上記ブーツ１８の外端部内周面との係合に基づき、このブーツ１８の抜け止めを図る為の係止溝２０を形成している。本例の場合には、この様な間座４６を構成する外径側円筒部４８の外半部を上記１対の止め輪素子２６、２６の周囲に配置して、これら両止め輪素子２６、２６が直径方向外方に変位する事を阻止し、上記止め輪１６ａが上記係止凹溝１５から外れない様にしている。
【００３３】
一方、ハブ４ａの中間部外周面には、この中間部外周面に形成した肉盗み部２５を覆う様にして、トーンホイール３６を、締り嵌めで外嵌固定している。このトーンホイール３６は、前述の図４に示した第３例に使用したトーンホイール３６と同様のものである。そして、このトーンホイール３６と組み合わせて回転速度検出装置を構成するセンサ３８ｂを、外輪１に支持固定している。即ち、この外輪１の軸方向中間部に、この外輪１の内周面と外周面とを連通させる状態で形成した取付孔５０に上記センサ３８ｂの一部を挿入し、ねじ５１により、このセンサ３８ｂを上記外輪１に固定している。この状態でこのセンサ３８ｂの先端面に設けた検出部と上記トーンホイール３６の中間部外周面とを、微小隙間を介して対向させている。又、上記センサ３８ｂの中間部外周面に係止したＯリング５２の外周縁を上記取付孔５０の内周面に、全周に亙り当接させて、この取付孔５０を介して上記外輪１内に異物が入り込む事を防止している。尚、上記センサ３８ｂの信号は、このセンサ３８ｂの基端部からこのセンサ３８ｂの軸方向に対して直角方向に導出したハーネス５３により取り出し、図示しない制御器に送る様にしている。尚、本例の様に、前記ブーツ１８の外端部を止め輪１６ａの周囲に配置固定する構造にすれば、上記ハブ４ａの軸方向長さを小さくして、車輪用転がり軸受ユニット全体としての小型・軽量化を図れる。その他の構成及び作用は、前述の図１〜２に示した第１例と同様であるから、同等部分には同一符号を付して、重複する説明を省略する。
【００３４】
次に、図７〜８は、請求項３に対応する、本発明の実施の形態の第６例を示している。本例の場合、それぞれの内周縁部を係止凹溝１５に係合させた各止め輪素子２６、２６の周囲に、これら各止め輪素子２６、２６が直径方向外方に変位するのを阻止する抑え環５４を、隙間嵌で外嵌している。この様な抑え環５４は、ＳＰＣＣの如き鋼板等の金属板を欠円環状に曲げ形成して成る。この金属板の円周方向両端縁同士は、必要に応じて溶接し、直径方向外方に向く力に対する剛性を向上させる。但し、上記各止め輪素子２６、２６に作用する直径方向外方に向く力は限られたものであるから、必ずしも上記円周方向両端縁同士を溶接しなくても良い。そして、溶接しない場合には、上記抑え環５４に内径を縮める方向に弾力を付与し、この抑え環５４の内周面を上記各止め輪素子２６、２６の外周面に、弾性的に当接させても良い。
【００３５】
一方、ハブ４ｃの内端部には、ブーツ１８ｂの外端部を外嵌固定している。そして、このブーツ１８ｂの外端縁を上記抑え環５４の軸方向内端縁部に、近接若しくは当接させている。この構成により上記抑え環５４は、軸方向両側に存在する内輪６の内端面と上記ブーツ１８ｂの外端縁とにより、軸方向にずれ動く事を阻止される。この結果、上記抑え環５４が軸方向にずれ動き、この抑え環５４が上記各止め輪素子２６、２６の周囲から外れる事がなくなる。又、図示の例では、上記ブーツ１８ｂの外端縁の外周縁部から軸方向外方に突出させた抑え部５５の内周面を、上記抑え環５４の外周面に当接若しくは近接させている。この様な抑え部５５は、上記各止め輪素子２６、２６に隙間嵌により外嵌した上記抑え環５４が、上記ハブ４ｃの回転に伴って振れ回り運動する事を防止する。この様に、ブーツ１８ｂの一部により、止め輪１６ａの周囲に配置した抑え環５４の抜け止めと振れ回りの防止とを図っているので、車輪用軸受ユニットの軸方向寸法が嵩む事はない。これに対して、図９に示す様に、断面クランク形の抑え環５８をハブ４ｃに外嵌して止め輪１６ａの抜け止めを図った場合には、上記軸方向寸法が嵩む為、好ましくない。
【００３６】
又、本例の場合には、上記ハブ４ｃをより一層軽量化して、車輪用転がり軸受ユニット全体としての軽量化をより顕著なものにすべく、次の様な工夫を施している。先ず第一に、上記ハブ４ｃの外半部内周面に旋削加工を施して、この部分の内径を大きくしている。又、前述の図５に示した第４例の場合と同様に、上記ハブ４ｃを、軸方向両端面同士を連通させる、中空円筒状に形成すると共に、このハブ４ｃの中間部内周面に塞ぎ板４４ａを内嵌固定している。更に、このハブ４ｃの外端開口部には、鋼板等により時計皿状に形成した第二の塞ぎ板５６を内嵌固定して、上記外端開口部から上記ハブ４ｃ内に、雨水等の異物が入り込む事を防止している。そして、上記旋削加工により薄肉になった上記ハブ４ｃの外端部が内周面側から腐蝕する事を防止して、このハブ４ｃの耐久性確保を図っている。尚、上記外端開口部からの異物進入防止を図る為には、上記第二の塞ぎ板５６に隣接した部分に設けた内向フランジ状の鍔部５７を、上記ハブ４ｃの中心部にまで延長して隔壁とする事が考えられる。この場合には、上記第二の塞ぎ板５６を省略して、コストの低減を図れる反面、軽量化が難しくなる。
【００３７】
尚、本例の場合には、フランジ７にスタッドを固定せず、代わりに、このフランジ７にねじ孔６１、６１を設けている。この様に構成する理由は、上記フランジ７に車輪を取り付ける為のボルトのピッチ円径を少しでも小さくする為である。即ち、フランジ７にスタッドを固定する場合には、このスタッドを構成するねじ部の外径よりも大きな外径を有するスタッドの頭部とシールリング１４のリップとの干渉を防止する必要上、上記各スタッドを、上記頭部の外径が大きい分だけ、上記フランジ７の直径方向外方に配置する必要がある。これに対して、本例の様に上記フランジ７にねじ孔６１、６１を形成し、このフランジ７への車輪の取り付けを、車輪を外方から内方に（図７の左から右に）挿通した複数本のボルトにより行なう様にすれば、このボルトの頭部を車輪の外側（図７の左側）に配置して、この頭部の一部を上記シールリップよりも直径方向内側に配置する事が可能になる。その他の構成及び作用は、前述の図１〜２に示した第１例と同様であるから、同等部分には同一符号を付して、重複する説明を省略する。
【００３８】
次に、図１０は、やはり請求項３に対応する、本発明の実施の形態の第７例を示している。本例の場合には、止め輪１６ａを構成する１対の止め輪素子２６、２６の周囲に設ける抑え環５４ａを、断面Ｌ字形で全体を円環状に形成している。即ち、この抑え環５４ａは、円筒部５９の内端縁部に、内向フランジ状の円輪部６０を形成して成る。この様な形状の抑え環５４ａの場合には、ブーツ１８ｂの外端縁部に形成した抑え部５５の基端部内周面が、金属板を切断する際に生じる、鋭利な端縁により傷められる事がない。即ち、上記抑え部５５の基端部内周面は、上記円筒部５９と円輪部６０とを連続させる湾曲部と対向するので、すれ合いに基づいて傷む事はない。尚、本例に使用する抑え環５４ａは、金属板をプレス加工する事により造っても良いが、合成樹脂の射出成形により造る事もできる。即ち、上記抑え環５４ａは、上記円輪部６０の存在に基づいて十分な剛性を確保できるので、金属に比べて強度が低い合成樹脂により造っても、必要且つ十分な剛性を確保できる。その他の構成及び作用は、上述した第６例と同様である。
【００３９】
次に、図１１は、請求項４に対応する、本発明の実施の形態の第８例を示している。本例の場合には、ハブ４ｄの内端寄り部分で内輪６を外嵌固定する部分の外径Ｄ₄ を、このハブ４ｄの中間部で第一の内輪軌道１１を形成した部分の外径Ｄ₁₁よりも大きく（Ｄ₄ ＞Ｄ₁₁）している。従って本例の場合には、上述した第１〜７例の場合に比べても、上記第一の内輪軌道１１の直径を上記内輪６の外周面に形成した第二の内輪軌道１２の直径に比べて、より小さくできる。又、外輪１の外端開口部と上記ハブ４ｄの中間部外周面との間をシールする為のシールリング１４ａを、このハブ４ｄの中間部外周面に外嵌固定している。このシールリング１４ａは、このハブ４ｄの中間部に外嵌固定する芯金６２と、この芯金６２の外周面及び内側面に添着した弾性材製のシールリップ６３とから成る。このシールリップ６３の先端縁は、上記外輪１の外端開口部に嵌合固定したスリンガ６４の内周面及び外側面に摺接させている。上記ハブ４ｄの中間部で上記シールリング１４ａを外嵌固定する部分の外径Ｄ₁₄は、上記内輪６を外嵌固定する部分の外径Ｄ₄ 以上（Ｄ₁₄≧Ｄ₄ ）として、上記シールリング１４ａを上記内輪６を外嵌固定する部分を通過させられる様にしている。
【００４０】
又、上記外輪１の内周面に形成した複列の外輪軌道３ａ、３ｂと、上記ハブ４ｄ及び内輪６の外周面に形成した第一、第二の内輪軌道１１、１２との間にそれぞれ複数個ずつ、複列に設けた転動体１３、１３を、それぞれ円環状に構成した保持器６５ａ、６５ｂにより、転動自在に保持している。尚、図示は省略したが、前述の第１〜７例の構造の場合も、適宜保持器を設置する事は勿論である。特に、本例の場合には、外側の外輪軌道３ａと第一の内輪軌道１１との間に設けた転動体１３、１３を保持する保持器６５ａを、それぞれが円弧状に形成された保持器素子を組み合わせる事により、円周方向に亙って複数に分割自在とした、所謂分割保持器としている。従って、上記ハブ４ｄの内端寄り部分で内輪６を外嵌固定する部分の外径Ｄ₄ を、このハブ４ｄの中間部で第一の内輪軌道１１を形成した部分の外径Ｄ₁₁よりも大きくした構造に拘らず、上記保持器６５ａの組み付け作業を行なえる。内側の保持器６５ｂ（或は前述した第１〜７例に組み込む保持器）に就いては、この保持器６５ｂの内径よりも大径の部分を通過させる必要がないので、特に分割保持器とする必要はない。
【００４１】
又、本例の場合には、ハブ４ｄに車輪を固定する為、前述の図７に示した第６例の場合と同様に、フランジ７にねじ孔６１を設けている。特に、本例の場合には、これら各ねじ孔６１の両端開口周縁部のうち、上記フランジ７の内側面側開口周縁部に座ぐりを施して、上記各ねじ孔６１のタップ加工を容易に行なえる様にしている。又、上記内輪６の内端面を抑え付ける為の止め輪１６ａを、断面Ｌ字形で環状の抑え環５４ａにより抑え付けている。その他の部分の構成及び作用は、前述した何れかの実施の形態と同じであるから、同等部分には当該実施の形態を説明した図面と同一符号を付して、重複する説明を省略する。尚、以上に述べた第１〜８例の構造は、部分的に取り出して適宜組み合わせ実施できる事は勿論である。
【００４２】
尚、本発明の車輪用転がり軸受ユニットを構成するハブ４ａ、４ｂ、４ｃ、４ｄはＳ５３Ｃ〜Ｓ５５Ｃ程度の中炭素鋼を用い、鍛造、旋削、高周波焼入、研削、超仕上げの各工程を順次行なう事により造る。高周波焼き入れによる硬化部の１例に就いて、図７に斜格子で示す。止め輪１６ａを係止する為の係止凹溝１５部分は、強度を確保する必要上、焼き入れ硬化処理を施す。又、等速ジョイント９を構成するハウジング部１０の内周面に形成したボール溝部も、塑性変形の防止と転がり疲れ寿命の確保との為、焼き入れ硬化処理を施す。図７に示した例では、車輪用転がり軸受ユニットを極力軽量化すべく板厚を薄くする為に、上記ハウジング部１０の一部で、このハウジング部１０の外径側から形成した硬化層と内径側から形成した硬化層とを連続させている。この場合、外径側からの高周波焼き入れと内径側からの高周波焼き入れとを同時に行なう事が好ましい。この理由は、次の通りである。即ち、軽量化の為に板厚を薄くし、しかも十分な強度を確保する為には、上述の様に外径側から形成した硬化層と内径側から形成した硬化層とがつながった部分の心部硬さを、Ｈｖ５００以上にする事が好ましい。これに対して、同時に焼き入れせずに、外径側からの高周波焼き入れと内径側からの高周波焼き入れとを前後して行うと、先に焼き入れ硬化した部分の焼きがなまってしまい、上記心部硬さを確保できなくなる可能性がある。そこで、外径側からの高周波焼き入れと内径側からの高周波焼き入れとを同時に行なう。又、フランジ７の付け根の強度確保と、シールリング１４のシールリップが摺動する面の摩耗防止の為に、これらの部分に焼き入れ硬化処理を施す。但し、図７に示した構造の様に、上記シール１４のシールリップが摺動する面と、上記フランジ７に形成したねじ孔６１、６１とが近接している場合には、これら各ねじ孔６１、６１部分が焼き入れ硬化されない様に、上記シールリップの摺動面の途中から焼きを入れない構造にする。
【００４３】
【発明の効果】
本発明は、以上に述べた通り構成され作用するので、小型且つ軽量な車輪用転がり軸受ユニットを実現して、燃費、乗り心地等の面から、自動車の性能向上に寄与できる。
【図面の簡単な説明】
【図１】本発明の実施の形態の第１例を示す断面図。
【図２】止め輪を図１の側方から見た図。
【図３】本発明の実施の形態の第２例を示す断面図。
【図４】同第３例を示す断面図。
【図５】同第４例を示す断面図。
【図６】同第５例を示す断面図。
【図７】同第６例を示す断面図。
【図８】図７のＡ部拡大図。
【図９】好ましくない構造を示す、図８と同様の図。
【図１０】本発明の実施の形態の第７例を示す、図８と同様の図。
【図１１】同第８例を示す断面図。
【図１２】従来構造の１例を示す断面図。
【符号の説明】
１外輪
２取付部
３、３ａ、３ｂ外輪軌道
４、４ａ、４ｂ、４ｃ、４ｄハブ
５第一の内輪
６第二の内輪（内輪）
７フランジ
８スタッド
９等速ジョイント
１０ハウジング部
１１第一の内輪軌道
１２第二の内輪軌道
１３転動体
１４、１４ａシールリング
１５係止凹溝
１６、１６ａ止め輪
１７段部
１８、１８ａ、１８ｂブーツ
１９抑えバンド
２０係合溝
２１駆動軸
２２内輪
２３玉
２４頭部
２５肉盗み部
２６止め輪素子
２７抑え部
２８小径円筒部
２９円輪部
３０大径円筒部
３１金属板
３２断熱層
３３環状空間
３４スリンガ
３５、３５ａシールリップ
３６トーンホイール
３７透孔
３８、３８ａ、３８ｂセンサ
３９エンコーダ
４０支持環
４１エンコーダ本体
４２円筒部
４３円輪部
４４、４４ａ塞ぎ板
４５隔壁
４６間座
４７内径側円筒部
４８外径側円筒部
４９連結部
５０取付孔
５１ねじ
５２Ｏリング
５３ハーネス
５４、５４ａ抑え環
５５抑え部
５６第二の塞ぎ板
５７鍔部
５８抑え環
５９円筒部
６０円輪部
６１ねじ孔
６２芯金
６３シールリップ
６４スリンガ
６５ａ、６５ｂ保持器[0001]
BACKGROUND OF THE INVENTION
The wheel rolling bearing unit according to the present invention includes a front wheel of an FF vehicle (front engine front wheel drive vehicle), an FR vehicle (front engine rear wheel drive vehicle), and an RR vehicle (rear engine rear wheel drive vehicle) rear wheel. Drive wheels such as all wheels of a 4WD vehicle (four-wheel drive vehicle) are used to rotatably support 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, a wheel rolling bearing unit for supporting a drive wheel supported by an independent suspension type suspension is combined with a constant velocity joint so that the rotation of the drive shaft is applied to the wheel regardless of the relative displacement between the wheel and the differential gear. On the other hand, it is necessary to transmit smoothly (assuring constant speed). This is particularly important when the steered wheel and the drive shaft coincide. Conventionally, a rolling bearing unit for a wheel that can be combined with such a constant velocity joint and can be made relatively small and light is disclosed in Japanese Utility Model Laid-Open No. 61-113103.
[0003]
  FIG. 12 shows a conventional structure described in this publication. The outer ring 1 that does not rotate while being supported by the suspension device in the state of being mounted on the vehicle has an outward flange-like mounting portion 2 for supporting the suspension device on the outer peripheral surface, and a double row outer ring track 3 on the inner peripheral surface. 3 respectively. A hub 4 and first and second inner rings 5 and 6 are provided inside the outer ring 1. Of theseThe outer peripheral surface of the hub 4The outer end (outside means the side that is outward in the width direction when assembled to the automobile, and is the left side of FIG. 12 and FIGS. 1 and 3 to be described later. The flange 7 for supporting and fixing the wheel to the hub 4 is formed integrally with the hub 4 at a portion closer to the hub 4. A plurality of (usually 4 to 6) studs 8 are press-fitted and fixed in the axial direction on the flange 7 at equal intervals in the circumferential direction, and the plurality of studs 8 are used during assembly. The wheel is supported and fixed to the flange 7. Further, the inner end side portion of the hub 4 is a housing portion 10 which becomes an outer ring of the constant velocity joint 9.
[0004]
The first and second inner rings 5 and 6 are externally fitted and fixed to the intermediate portion of the hub 4. First and second inner ring raceways 11 and 12 are formed on the outer peripheral surfaces of the first and second inner rings 5 and 6, respectively. Then, a plurality of rolling elements 13 and 13 are provided between the outer ring raceways 3 and 3 and the first and second inner ring raceways 11 and 12, respectively. 4 and the first and second inner rings 5 and 6 are rotatably supported. Incidentally, both end openings of the annular space provided with the respective rolling elements 13, 13, that is, the inner peripheral surface of both ends of the outer ring 1, the outer peripheral surface of the outer end portion of the first inner ring 5, and the second inner ring 6. The gaps between the outer peripheral surface of the inner end portions are closed by seal rings 14 and 14, respectively. Further, a locking groove 15 is formed over the entire circumference of the outer peripheral surface of the hub 4 near the inner end of the intermediate portion of the hub 4, and a notched annular retaining ring 16 is formed in the locking groove 15. Is locked. The first and second inner rings 5 and 6 are sandwiched from both sides in the axial direction between the retaining ring 16 and a stepped portion 17 formed in the proximal end inner portion of the flange 7. In this state, the retaining ring 16 prevents the first and second inner rings 5 and 6 from moving to the axially inner end side of the hub 4.
[0005]
Further, the outer end portion of the boot 18 formed in a bellows shape by an elastic material such as rubber or synthetic resin is engaged with the outer peripheral surface of the inner end portion of the housing portion 10. In other words, the cylindrical portion that is externally fitted to the inner end portion of the housing portion 10 at the outer end portion of the boot 18 is held down by the holding band 19. And the outer peripheral part inner peripheral surface of the said boot 18 and the engaging groove 20 formed in the inner end part outer peripheral surface of the said housing part 10 are engaged over the perimeter. The other end of the boot 18 is tightly coupled to the outer peripheral surface (not shown) of the intermediate portion of the drive shaft 21 that is rotationally driven by the engine via the transmission. Such a boot 18 blocks the inner space of the housing part 10 from the outside, prevents the grease existing in the inner space from leaking to the outside, and allows foreign matters such as rainwater and dust to enter the inner space. Prevent intrusion.
[0006]
  When the rolling bearing unit for a wheel configured as described above is assembled to a vehicle, the outer ring 1 is supported and fixed to the suspension device by the mounting portion 2, and the driving wheel is supported and fixed to the hub 4 by the flange 7. Further, the tip end portion of the drive shaft 21 that is rotationally driven by the engine via the transmission is spline-engaged with the inner diameter side of the inner ring 22 constituting the constant velocity joint 9. When the automobile is running, the rotation of the inner ring 22 is transmitted to the hub 4 via a plurality of balls 23, and theDriving wheelIs driven to rotate.
[0007]
[Problems to be solved by the invention]
In the case of the conventional structure shown in FIG. 12, it is difficult to reduce the size and weight of the wheel rolling bearing unit. The reason for this is as follows. That is, in the case of the conventional structure described above, the formation position of the flange 7 for fixing the stud 8 is shifted outward in the axial direction in order to prevent interference between the stud 8 and the first inner ring 5. In this manner, the axial dimension of the hub 4 is increased by the amount that the flange 7 is formed to be displaced outward in the axial direction, and the wheel rolling bearing unit cannot be reduced in size and weight.
[0008]
If the outer diameter of the flange 7 is increased and the fixing position of the stud 8 is shifted outward in the diametrical direction to prevent interference between the head 24 of each stud 8 and the outer end of the outer ring 1, It is possible to reduce the directional dimension. However, in this case, the pitch circle diameter (p.c.d.) of the plurality of studs 8 supported and fixed to the flange 7 becomes larger than necessary, and the wheel rolling bearing unit cannot be reduced in size and weight. An increase in the weight of the wheel rolling bearing unit is not preferable because it leads to an increase in the unsprung load of the automobile, leading to deterioration in the riding comfort performance and fuel consumption performance of the automobile.
In view of such circumstances, the present invention can reduce the axial dimension and the pcd of the stud 8 for supporting and fixing the wheel so as to achieve a wheel rolling bearing unit that can be reduced in size and weight. It is what I thought.
[0009]
[Means for Solving the Problems]
  The wheel rolling bearing unit of the present invention has a mounting portion for supporting the suspension device on the outer peripheral surface and a double row outer ring raceway on the inner peripheral surface in the same manner as the wheel rolling bearing unit shown in FIG. A flange for supporting and fixing the wheel on the outer ring and a portion of the outer peripheral surface near one end of the outer ring that protrudes from the outer ring in the axial direction; A hub with a side portion serving as a housing part serving as an outer ring of a constant velocity joint, and a second inner ring raceway formed on the outer peripheral surface, and other than the part where the first inner ring raceway is formed in the intermediate part of the hub A hub is provided inside the outer ring by providing a plurality of inner rings that are fitted and fixed to the end portion, a plurality of outer ring raceways and the first and second inner ring raceways. And a plurality of rotatably supporting inner rings And the moving bodyA seal ring for closing an annular gap between the inner peripheral surface of one end of the outer ring and the outer peripheral surface of the intermediate portion of the hub;Is provided.
[0010]
  In particular, in the rolling bearing unit for wheels of the present invention,The flange and the housing part are formed integrally with the hub,The first inner ring racewaythisWhile forming directly on the outer peripheral surface of the middle part of the hub,Of the outer peripheral surface of the intermediate portion of the hub, the outer diameter of the portion between the first inner ring raceway and the inner surface of the base end portion of the flange where the seal ring is disposed is set to the outer diameter of the inner ring. It is larger than the outer diameter of the fixed part,The pitch circle diameter of the plurality of rolling elements constituting the rolling element row relating to the first inner ring raceway is made smaller than the pitch circle diameter of the plurality of rolling elements constituting the rolling element row relating to the second inner ring raceway. Yes.
[0011]
[Action]
In the case of the rolling bearing unit for a wheel of the present invention configured as described above, the axial dimension of the hub is increased by the small pitch circle diameter of the rolling element on the flange side for fixing the stud for supporting and fixing the wheel. The outer diameter of the flange can be reduced without doing so. Therefore, the wheel rolling bearing unit can be reduced in size and weight by reducing the outer diameter of the flange.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first example of an embodiment of the present invention. The wheel rolling bearing unit of the present invention is characterized in that the structure of the rolling bearing portion constituting the wheel rolling bearing unit is devised in order to reduce the size and weight. Since the structure and operation of the other parts are almost the same as those of the conventional structure shown in FIG. 12, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. The description will focus on the part and the part different from the conventional structure.
[0013]
In the case of the wheel rolling bearing unit of the present invention, the first inner ring raceway 11 is formed directly on the outer peripheral surface of the intermediate portion of the hub 4a. In addition, an inner ring 6 having a second inner ring raceway 12 formed on the outer peripheral surface thereof is externally fitted to a portion closer to the inner end than the portion where the first inner ring raceway 11 is formed in the intermediate portion of the hub 4a. . Then, as described above, the first inner ring raceway 11 is formed directly on the outer peripheral surface of the hub 4a, whereby the diameter of the first inner ring raceway 11 is formed on the outer peripheral surface of the inner ring 6. The diameter of the inner ring raceway 12 is smaller. Further, as the diameter of the first inner ring raceway 11 is made smaller than the diameter of the second inner ring raceway 12 in this way, the outer ring raceway on the outer side (left side in FIG. 1) facing the first inner ring raceway 11. The diameter of 3a is made smaller than the diameter of the inner ring (right side in FIG. 1) outer ring raceway 3b. Further, the outer diameter of the outer half of the outer ring 1 that forms the outer ring raceway 3a on the outside is made smaller than the outer diameter of the inner half of the outer ring 1 that is the part that forms the inner outer ring raceway 3b. ing.
[0014]
That is, since the first inner ring raceway 11 is formed directly on the outer peripheral surface of the intermediate portion of the hub 4a, the diameter of the first inner ring raceway 11 is the same as that of the conventional structure shown in FIG. One inner ring raceway 11 can be made smaller than the case where it is provided on the outer peripheral surface of the hub 4 via the first inner ring 5. Therefore, among the rolling element rows provided in the double row, the pitch circle diameter of each of the rolling elements 13 and 13 constituting the outer (left side in FIG. 1) is the inner (right side in FIG. 1) rolling element row. Is smaller than the pitch circle diameter of each rolling element 13, 13. Further, in the example shown in the drawing, as the diameters of the first inner ring raceway 11 and the outer outer ring raceway 3a are reduced in this way, the rolls provided between the first inner ring raceway 11 and the outer outer ring raceway 3a are provided. The number of moving bodies 13, 13 is smaller than the number of rolling elements 13, 13 provided between the second inner ring raceway 12 and the inner outer ring raceway 3b.
[0015]
The pitch circle diameter of the plurality of studs 8 provided on the flange 7 of the hub 4a is equal to the outer diameter of the outer half of the outer ring 1 smaller than the outer diameter of the inner half as described above (see above). The head 24 of each stud 8 is made small (so as not to interfere with the outer peripheral surface of the outer end portion of the outer ring 1). Of the outer peripheral surface of the hub 4a, the diameter of the portion existing in the axial direction from the portion where the first inner ring raceway 11 is formed is the rolling element 13 corresponding to the first inner ring raceway 11. , 13 is smaller than the diameter of the inscribed circle. This is because, when the rolling bearing unit for the wheel is assembled, a plurality of rolling elements 13 and 13 are assembled on the inner diameter side of the outer ring raceway 3a formed on the inner peripheral surface of the outer ring 1 and the inner periphery of the outer ring 1 is assembled. This is because the hub 4a can be freely inserted into the inner diameter side of the outer ring 1 with the seal ring 14 fitted and fixed to the surface. Further, on the outer peripheral surface of the intermediate portion of the hub 4a, a groove stealing portion 25 having a groove shape is formed over the entire circumference between the first inner ring raceway 11 and the portion where the inner ring 6 is externally fitted. Thus, the hub 4a is reduced in weight.
[0016]
Further, the inner ring 6 fitted on the hub 4a is prevented from being displaced toward the inner end side in the axial direction, and between the outer ring raceways 3a and 3b and the first and second inner ring raceways 11 and 12, respectively. Locking recesses formed over the entire circumference at the inner peripheral portion of the outer peripheral surface of the hub 4a in order to keep the preload applied to each of the rolling elements 13, 13 at appropriate values. A retaining ring 16 a is locked in the groove 15. The retaining ring 16a is composed of a pair of semi-circular retaining ring elements 26, 26 as shown in FIG. Such retaining ring elements 26 and 26 are configured to press the inner ring 6 axially outward against the hub 4a while applying the appropriate preload to the rolling elements 13 and 13, respectively. The portion is engaged with the locking groove 15. In order to keep an appropriate preload applied to the rolling elements 13 and 13 even in a state in which the force pressing the inner ring 6 outward in the axial direction is released, Select one with thickness dimension. That is, a plurality of types of the retaining ring elements 26, 26 having slightly different thickness dimensions are prepared, and the relationship with the dimensions of the constituent members of the rolling bearing unit, such as the groove width of the locking groove 15. Retaining ring elements 26, 26 having appropriate thickness dimensions are selected and engaged with the locking grooves 15. Therefore, by locking each of the retaining ring elements 26, 26 in the retaining groove 15, the inner ring 6 is prevented from moving to the inner end side in the axial direction even when the pressing force is released. Thus, the rolling elements 13 and 13 can be held with an appropriate preload applied.
[0017]
In addition, the pair of retaining ring elements 26, 26 are displaced outward in the diametrical direction, and the pair of retaining ring elements 26, 26 are prevented from being inadvertently detached from the locking groove 15. A part of the boot 18a is arranged around the retaining ring elements 26, 26. The boot 18a is for preventing foreign matter such as rainwater and dust from entering the constant velocity joint formed by the housing portion 10 provided at the inner end portion of the hub 4a. It is integrally formed of an elastic material, and an intermediate portion is formed in a bellows shape and both end portions are formed in a cylindrical shape. The outer end portion of the boot 18a is externally fitted to the inner end portion of the hub 4a, and is pressed against the outer peripheral surface of the inner end portion of the hub 4a by the restraining band 19, so that the inner peripheral surface of the outer end portion of the boot 18a. And the engaging groove 20 formed on the outer peripheral surface of the inner end portion of the housing portion 10 are engaged over the entire circumference.
[0018]
A portion of the outer edge of the boot 18a that protrudes outward in the axial direction from the restraining band 19 is formed in a cross-sectional crank shape to constitute a restraining portion 27 that extends over the entire circumference. The holding portion 27 includes a small-diameter cylindrical portion 28 that is externally fitted to the inner end portion of the hub 4a, an annular portion 29 that is bent radially outward from an outer end edge of the small-diameter cylindrical portion 28, and the annular portion. 29, and a large-diameter cylindrical portion 30 bent outward in the axial direction from the outer peripheral edge. Of these, the outer surface of the circular ring portion 29 is abutted against the inner surface of the retaining ring 16a, and the large-diameter cylindrical portion 30 is externally fitted to the retaining ring 16a.
[0019]
The operation of rotatably supporting the wheel with respect to the suspension device by the wheel rolling bearing unit of the present example configured as described above is the same as that of the conventional wheel rolling bearing unit described above. In particular, in the case of this example, the outer diameter of the outer half portion of the outer ring 1 can be reduced by reducing the pitch circle diameter of the rolling elements 13 and 13 constituting the outer rolling element row. The pitch circle diameter of the plurality of studs 8 provided on the flange 7 of the hub 4a can be reduced by the amount that the outer diameter of the outer half of the outer ring 1 is reduced. Therefore, unlike the conventional structure described above, the outer diameter of the flange 7 for supporting and fixing the stud 8 is reduced without increasing the axial dimension of the hub 4a, thereby reducing the size and weight of the wheel rolling bearing unit. Can be realized.
[0020]
Further, by making the pitch circle diameter of the rolling elements 13 and 13 constituting the outer rolling element row smaller than the pitch circle diameter of the rolling elements 13 and 13 constituting the inner rolling element row, the outer rolling elements are formed. The basic dynamic load rating of the row portion is smaller than the basic dynamic load rating of the inner rolling element row portion. Therefore, if the load applied to both rows is the same, the life of the outer rolling element row portion is shorter than that of the inner rolling element row portion. In contrast, in a general automobile, the load applied to the outer rolling element row portion is smaller than the load applied to the inner rolling element row portion. For this reason, the design which makes the lifetime of the both row portions substantially the same becomes easy, and the design without waste becomes possible. In the illustrated example, balls are used as the rolling elements 13, 13, but in the case of a rolling bearing unit for automobiles that is heavy, tapered rollers may be used as the rolling elements. Of course, the present invention can also be applied to a rolling bearing unit that uses a tapered roller as a rolling element.
[0021]
Next, FIG. 3 shows a second example of the embodiment of the present invention. In the case of this example, in order to more reliably prevent the pair of retaining ring elements 26, 26 constituting the retaining ring 16 a retained in the retaining groove 15 from falling out of the retaining groove 15, the boot The rigidity of the portion covering the periphery of the pair of retaining ring elements 26, 26 at the outer end portion 18a is improved. For this reason, in the case of this example, a metal plate 31 that is crank-shaped in cross section and formed entirely in a ring shape is fitted on the outer end of the boot 18a. The metal plate 31 is pressed against the outer peripheral surface of the inner end portion of the hub 4a together with the outer end portion of the boot 18a by the holding band 19 in the assembled state to the suspension device. In this state, the metal plate 31 prevents the holding portion 27 formed on the outer end portion of the boot 18a made of an elastic material from being deformed outward in the diameter direction. Therefore, the large-diameter cylindrical portion 30 of the restraining portion 27 reliably prevents the pair of retaining ring elements 26, 26 from being displaced outward in the diametrical direction.
[0022]
Of the surface of the inner ring 6 fitted on the hub 4a, an inner peripheral surface facing the outer peripheral surface of the hub 4a and an inner surface facing the outer surface of the pair of retaining ring elements 26, 26 are provided. Forms a heat insulating layer 32 made of a heat insulating material such as ceramic or synthetic resin. The heat insulating layer 32 prevents heat generated at the constant velocity joint portion from being transmitted to the inner ring 6 via the hub 4a and the retaining ring 16a facing the inner ring 6 when the wheel rolling bearing unit for the wheel is used. . For this reason, the temperature rise of the seal ring 14 which blocks the inner end opening of the annular space 33 in which the rolling elements 13 and 13 are installed can be suppressed. As a result, it is necessary to use an expensive material having particularly excellent heat resistance as the seal lip 35 made of an elastic material that constitutes the seal ring 14 and is in sliding contact with the slinger 34 fitted and fixed to the outer peripheral surface of the inner ring 6. Disappears. Specifically, even if the seal lip 35 is made of a relatively inexpensive material such as nitrile butadiene rubber (NBR) or H-nitrile butadiene rubber (H-NBR), sufficient durability can be obtained.
[0023]
  In order to suppress the temperature rise of the slinger 34 with which the seal lip 35 is slidably contacted, a heat insulating layer may be interposed at any portion between the slinger 34 and the hub 4a. For example, the heat insulating layer is formed on the inner peripheral surface of the slinger 34, or the intermediate outer peripheral surface of the hub 4a and the retaining ring.16aIt can also be formed on the outer surface of the. Furthermore, a heat insulating layer can be interposed at a plurality of locations that exist in series in the heat transfer direction. Other configurations and operations are the same as those in the case of the first example shown in FIGS. 1 and 2 described above, and thus the same parts are denoted by the same reference numerals and redundant description is omitted.
[0024]
Next, FIG. 4 shows a third example of the embodiment of the present invention. In the case of this example, the present invention is applied to a wheel rolling bearing unit with a rotation speed detection device that has a function of rotatably supporting a wheel on a suspension device and detecting the rotation speed of the wheel. In the case of this example, a cylindrical tone wheel 36 is externally fixed by an interference fit to a pair of retaining ring elements 26, 26 constituting a retaining ring 16a locked in the locking groove 15. . The tone wheel 36 is formed by forming a magnetic metal plate such as a soft steel plate such as SPCC into a cylindrical shape, and each of the intermediate portions in the axial direction (left-right direction in FIG. 4) has slit-like through holes each having a long axial direction. A large number of 37 and 37 are formed at equal intervals in the circumferential direction. In such a tone wheel 36, a large number of the through holes 37, 37 and a column portion existing between the through holes 37, 37 adjacent to each other in the circumferential direction alternately exist in the circumferential direction. To do. Accordingly, the magnetic characteristics of the outer peripheral surface of the tone wheel 36 change alternately and at equal intervals over the circumferential direction.
[0025]
The pair of retaining ring elements 26, 26 constituting the retaining ring 16 a are prevented from being displaced outward in the diametrical direction by suppressing the outer peripheral surfaces of the pair of retaining ring elements 26, 26 with such a tone wheel 36. It is prevented from coming out of the groove 15. The detection surface provided at the tip of the sensor 38 supported and fixed to a fixed portion (not shown) such as a knuckle constituting the suspension device is opposed to the outer peripheral surface of the tone wheel 36 with a minute gap therebetween, and the hub 4a. A rotation speed detection device for detecting the rotation speed of the rotating wheel is configured. Other configurations and operations are the same as those in the case of the first example shown in FIGS. 1 and 2 described above, and thus the same parts are denoted by the same reference numerals and redundant description is omitted.
[0026]
Next, FIG. 5 shows a fourth example of the embodiment of the present invention. Also in this example, the present invention is applied to a rolling bearing unit for a wheel with a rotational speed detection device. In the case of this example, an encoder 39 is externally fitted to a pair of retaining ring elements 26, 26 constituting the retaining ring 16a that is engaged with the retaining groove 15, so that both the retaining ring elements 26, 26 have a diameter. Prevents displacement outward. The encoder 39 includes a support ring 40 formed by bending a magnetic metal plate and having an L-shaped cross section, and an encoder body 41 that is an annular permanent magnet. Among these, the support ring 40 includes a cylindrical portion 42 and an annular portion 43 that is bent outward in the diameter direction from the outer end portion of the cylindrical portion 42. The retaining ring 16a is externally fitted with a cylindrical portion 42, so that the encoder 39 is supported and fixed around the retaining ring 16a. The retaining ring 16a is fixed to the retaining groove 16a. I am trying not to come off 15.
[0027]
On the other hand, the encoder body 41 is attached and fixed to the inner surface of the annular portion 43 of the support ring 40 over the entire circumference by baking, bonding, own magnetic attraction force, or the like. For example, the encoder main body 41, which is a rubber magnet formed by mixing ferrite powder in rubber, is magnetized in the axial direction (left-right direction in FIG. 5). The magnetization direction is changed alternately at equal intervals over the circumferential direction. Accordingly, N poles and S poles are alternately arranged at equal intervals on the inner surface of the encoder body 41. On the inner side surface of such an encoder body 41, a wheel that rotates with the hub 4b with a detection surface provided at the tip of a sensor 38a supported and fixed to a fixed portion (not shown) facing in the axial direction through a minute gap. A rotation speed detection device for detecting the rotation speed of the motor is configured.
[0028]
In order to secure the output of the sensor 38a, the width dimension W of the encoder body 41 in the diameter direction is used.₄₁It is preferable to increase the amount of magnetic flux emitted from the encoder body 41. In the case of this example, since the encoder 39 is externally fitted and fixed to the retaining ring 16a having a smaller diameter than the inner ring 6, the width dimension W₄₁Is easy to secure. That is, the inner surface of the slinger 34 that is externally fitted and fixed to the inner end of the inner ring 6 can be considered as a portion that supports the annular encoder body 41. According to the structure of this example, the slinger 34 is provided with an encoder. Compared to the case where a main body is provided, the above width dimension W₄₁Can be increased.
[0029]
Further, in the case of this example, in order to reduce the weight of the wheel rolling bearing unit, the hub 4b is formed in a hollow cylindrical shape in which both end surfaces in the axial direction are communicated with each other. A closing plate 44 is fitted and fixed to the inner peripheral surface of the intermediate portion of the hub 4b to block communication between the outer end opening and the inner end opening of the hub 4b. The closing plate 44 prevents foreign matters such as rain water and dust existing outside from entering the constant velocity joint including the housing portion 10 provided at the inner end portion of the hub 4b. Prevents grease in the high speed joint from leaking to the outside. In order to effectively prevent the grease from moving from a necessary portion, the closing plate 44 is provided on a portion closer to the housing 10. Since such a closing plate 44 can be manufactured by pressing a steel plate having a thickness of about 1 mm or less, it is formed on the inner peripheral surface of the intermediate portion of the hub 4a, which is a forged product, as in the first to third examples. The hub 4b can be reduced in weight compared to the case where the partition walls 45 (FIGS. 1, 3, and 4) are integrally formed.
[0030]
Furthermore, in the case of this example, the diameter R of the inscribed circle of the heads 24 of the plurality of studs 8 that are supported and fixed to the flange 7._{twenty four}, The outer diameter D of the outer end of the outer ring 1₁ Smaller than (R_{twenty four}<D₁ The pitch circle diameter of the stud 8 is made as small as possible. Even in this case, the head 24 and the seal lip 35a of the seal ring 14 fitted and fixed to the outer end of the outer ring 1 are prevented from interfering with each other. In the case of the wheel rolling bearing unit of the present invention, the outer end portion of the outer ring 1 has a small diameter and the seal lip 35a has a small diameter. Diameter R of tangent circle_{twenty four}Can be made smaller than the conventional structure. Other configurations and operations are the same as in the case of the third example shown in FIG. 4 described above. Therefore, the same reference numerals are given to the equivalent parts, and duplicate descriptions are omitted. Although not shown in the drawings, in order to further reduce the pitch circle diameter of the plurality of studs, the outer peripheral edge shape of the head of each stud may not be circular, but may be a circular shape such as a D-shape. . In this case, even when the notch portion (D-shaped linear portion) of the head is positioned on the inner diameter side close to the seal lip 35a and the studs are provided close to the inner diameter side of the flange 7, The head and the seal lip 35a should not interfere with each other.
[0031]
Next, FIG. 6 shows a fifth example of the embodiment of the present invention. Also in this example, the present invention is applied to a rolling bearing unit for a wheel with a rotational speed detection device. However, in the case of this example, a space for fitting the outer end of the boot 18 around the pair of retaining ring elements 26, 26 constituting the retaining ring 16a locked in the locking groove 15 is provided. By disposing a part of the seat 46, both the retaining ring elements 26, 26 are prevented from being displaced outward in the diametrical direction.
[0032]
The spacer 46 is integrally formed of sintered metal or the like, has a cross-sectional shape of an h shape, and is formed in an annular shape as a whole. That is, the spacer 46 is connected to the inner diameter side cylindrical portion 47, the outer diameter side cylindrical portion 48, and the outer end edge of the inner diameter side cylindrical portion 47 and the inner peripheral surface of the intermediate portion of the outer diameter side cylindrical portion 48. Part 49. Among these, the inner diameter side cylindrical portion 47 is externally fixed to the inner end portion of the hub 4a by a sufficiently large interference fit so as to ensure a sufficiently large pulling force (for example, 100 kgf or more). A locking groove 20 is formed on the outer peripheral surface of the intermediate portion of the outer diameter side cylindrical portion 48 to prevent the boot 18 from coming off based on the engagement with the inner peripheral surface of the outer end portion of the boot 18. ing. In the case of this example, the outer half portion of the outer diameter side cylindrical portion 48 constituting such a spacer 46 is arranged around the pair of retaining ring elements 26, 26, and the both retaining ring elements 26. , 26 is prevented from displacing outward in the diametrical direction so that the retaining ring 16a does not come off from the retaining groove 15.
[0033]
On the other hand, the tone wheel 36 is fitted and fixed to the outer peripheral surface of the intermediate portion of the hub 4a by an interference fit so as to cover the meat stealing portion 25 formed on the outer peripheral surface of the intermediate portion. The tone wheel 36 is the same as the tone wheel 36 used in the third example shown in FIG. A sensor 38 b that forms a rotational speed detection device in combination with the tone wheel 36 is supported and fixed to the outer ring 1. That is, a part of the sensor 38b is inserted into the mounting hole 50 formed in a state where the inner peripheral surface and the outer peripheral surface of the outer ring 1 are communicated with each other in the axial direction intermediate portion of the outer ring 1, and the sensor 51 is 38 b is fixed to the outer ring 1. In this state, the detection portion provided on the front end surface of the sensor 38b and the outer peripheral surface of the intermediate portion of the tone wheel 36 are opposed to each other through a minute gap. Further, the outer peripheral edge of the O-ring 52 locked to the outer peripheral surface of the intermediate portion of the sensor 38b is brought into contact with the inner peripheral surface of the mounting hole 50 over the entire periphery, and the outer ring 1 is connected through the mounting hole 50. It prevents foreign matter from getting inside. The signal of the sensor 38b is taken out from the base end portion of the sensor 38b by a harness 53 that is led in a direction perpendicular to the axial direction of the sensor 38b, and sent to a controller (not shown). If the outer end of the boot 18 is arranged and fixed around the retaining ring 16a as in this example, the length of the hub 4a in the axial direction is reduced so that the wheel rolling bearing unit as a whole is made. Can be reduced in size and weight. Other configurations and operations are the same as those of the first example shown in FIGS. 1 and 2 described above, and therefore, the same parts are denoted by the same reference numerals and redundant description is omitted.
[0034]
Next, FIGS. 7 to 8 show a sixth example of an embodiment of the present invention corresponding to claim 3. In the case of this example, the retaining ring elements 26, 26 are displaced in the diametrically outward direction around the retaining ring elements 26, 26 having the respective inner peripheral edge portions engaged with the locking grooves 15. The retaining ring 54 to be blocked is externally fitted with a gap fit. Such a restraining ring 54 is formed by bending a metal plate such as a steel plate such as SPCC into a ring shape. The circumferential edges of the metal plate are welded as necessary to improve the rigidity against the force directed outward in the diameter direction. However, since the diametrically outward force acting on each of the retaining ring elements 26, 26 is limited, it is not always necessary to weld the circumferential end edges. When welding is not performed, elasticity is applied to the holding ring 54 in a direction to reduce the inner diameter, and the inner circumferential surface of the holding ring 54 is elastically brought into contact with the outer circumferential surfaces of the retaining ring elements 26 and 26. You may let them.
[0035]
On the other hand, the outer end of the boot 18b is fitted and fixed to the inner end of the hub 4c. Then, the outer edge of the boot 18b is brought close to or in contact with the inner edge of the holding ring 54 in the axial direction. With this configuration, the restraining ring 54 is prevented from moving in the axial direction by the inner end surface of the inner ring 6 existing on both sides in the axial direction and the outer end edge of the boot 18b. As a result, the restraining ring 54 is displaced in the axial direction, and the restraining ring 54 is not detached from the periphery of the retaining ring elements 26, 26. In the illustrated example, the inner peripheral surface of the holding portion 55 that protrudes outward in the axial direction from the outer peripheral edge portion of the outer edge of the boot 18b is brought into contact with or close to the outer peripheral surface of the holding ring 54. Yes. Such a restraining portion 55 prevents the restraining ring 54 that is externally fitted to the retaining ring elements 26 and 26 by a clearance fit from swinging along with the rotation of the hub 4c. In this way, a part of the boot 18b prevents the retaining ring 54 disposed around the retaining ring 16a from slipping out and prevents swinging, so that the axial dimension of the wheel bearing unit does not increase. . On the other hand, as shown in FIG. 9, when the retaining ring 58 having a cross-sectional crank shape is externally fitted to the hub 4c to prevent the retaining ring 16a from coming off, the axial dimension increases, which is not preferable. .
[0036]
In the case of this example, the following measures are taken in order to further reduce the weight of the hub 4c and make the weight of the entire rolling bearing unit for wheels more remarkable. First of all, the inner peripheral surface of the outer half of the hub 4c is turned to increase the inner diameter of this portion. Further, as in the case of the fourth example shown in FIG. 5 described above, the hub 4c is formed in a hollow cylindrical shape in which both end surfaces in the axial direction are communicated with each other, and the inner peripheral surface of the intermediate portion of the hub 4c is closed. The plate 44a is fitted and fixed. Further, a second closing plate 56 formed in a watch glass shape with a steel plate or the like is fitted and fixed to the outer end opening of the hub 4c, and rainwater or the like is inserted into the hub 4c from the outer end opening. Prevents foreign objects from entering. The outer end of the hub 4c, which has been thinned by the turning process, is prevented from being corroded from the inner peripheral surface side, thereby ensuring the durability of the hub 4c. In order to prevent foreign matter from entering from the outer end opening, an inward flange-shaped flange 57 provided in a portion adjacent to the second closing plate 56 is extended to the center of the hub 4c. It can be considered to be a partition wall. In this case, the second closing plate 56 can be omitted to reduce the cost, but it is difficult to reduce the weight.
[0037]
In the case of this example, the stud is not fixed to the flange 7, and instead, screw holes 61, 61 are provided in the flange 7. The reason for this configuration is to make the pitch circle diameter of the bolt for attaching the wheel to the flange 7 as small as possible. That is, when the stud is fixed to the flange 7, it is necessary to prevent interference between the head of the stud having an outer diameter larger than the outer diameter of the thread portion constituting the stud and the lip of the seal ring 14. It is necessary to dispose each stud on the outer side in the diameter direction of the flange 7 by an amount corresponding to the larger outer diameter of the head. On the other hand, screw holes 61 and 61 are formed in the flange 7 as in this example, and the wheel is attached to the flange 7 from the outside to the inside (from left to right in FIG. 7). If a plurality of inserted bolts are used, the head of the bolt is arranged outside the wheel (left side in FIG. 7), and a part of the head is arranged inside the seal lip in the diameter direction. It becomes possible to do. Other configurations and operations are the same as those of the first example shown in FIGS. 1 and 2 described above, and therefore, the same parts are denoted by the same reference numerals and redundant description is omitted.
[0038]
Next, FIG. 10 shows a seventh example of the embodiment of the present invention, which also corresponds to the third aspect. In the case of this example, the retaining ring 54a provided around the pair of retaining ring elements 26, 26 constituting the retaining ring 16a is formed in an annular shape with an L-shaped cross section. That is, the retaining ring 54 a is formed by forming an inward flange-shaped annular portion 60 at the inner end edge of the cylindrical portion 59. In the case of the holding ring 54a having such a shape, the inner peripheral surface of the base end portion of the holding portion 55 formed on the outer end edge portion of the boot 18b is damaged by a sharp edge that is generated when the metal plate is cut. There is nothing. That is, the inner peripheral surface of the base end portion of the holding portion 55 is opposed to the curved portion where the cylindrical portion 59 and the annular ring portion 60 are continuous, and therefore is not damaged based on the passing. The holding ring 54a used in this example may be made by pressing a metal plate, but can also be made by injection molding of a synthetic resin. In other words, the retaining ring 54a can ensure sufficient rigidity based on the presence of the annular portion 60, so that necessary and sufficient rigidity can be ensured even if it is made of a synthetic resin whose strength is lower than that of metal. Other configurations and operations are the same as those of the above-described sixth example.
[0039]
Next, FIG. 11 shows an eighth example of the embodiment of the present invention corresponding to claim 4. In the case of this example, the outer diameter D of the portion where the inner ring 6 is fitted and fixed near the inner end of the hub 4d._Four The outer diameter D of the portion where the first inner ring raceway 11 is formed at the intermediate portion of the hub 4d.₁₁Larger than (D_Four > D₁₁)is doing. Therefore, in the case of this example, the diameter of the first inner ring raceway 11 is made equal to the diameter of the second inner ring raceway 12 formed on the outer peripheral surface of the inner ring 6 as compared with the cases of the first to seventh examples. Compared to this, it can be made smaller. A seal ring 14a for sealing between the outer end opening of the outer ring 1 and the outer peripheral surface of the intermediate portion of the hub 4d is externally fixed to the outer peripheral surface of the intermediate portion of the hub 4d. The seal ring 14a includes a cored bar 62 that is fitted and fixed to an intermediate portion of the hub 4d, and a seal lip 63 made of an elastic material attached to the outer peripheral surface and the inner side surface of the cored bar 62. The leading edge of the seal lip 63 is brought into sliding contact with the inner and outer surfaces of the slinger 64 fitted and fixed to the outer end opening of the outer ring 1. The outer diameter D of the portion where the seal ring 14a is fitted and fixed at the intermediate portion of the hub 4d₁₄Is the outer diameter D of the portion where the inner ring 6 is externally fitted and fixed._Four (D₁₄≧ D_Four ), The seal ring 14a is allowed to pass through a portion where the inner ring 6 is externally fitted and fixed.
[0040]
Further, between the double row outer ring raceways 3a, 3b formed on the inner peripheral surface of the outer ring 1 and the first and second inner ring raceways 11, 12 formed on the outer peripheral surfaces of the hub 4d and the inner ring 6, respectively. A plurality of rolling elements 13 and 13 provided in a plurality of rows are held in a freely rotatable manner by retainers 65a and 65b each having an annular shape. In addition, although illustration was abbreviate | omitted, also in the case of the structure of the above-mentioned 1st-7th example, of course, a holder | retainer is installed suitably. In particular, in the case of this example, a cage 65a that holds the rolling elements 13 and 13 provided between the outer outer ring raceway 3a and the first inner ring raceway 11 is a cage that is formed in an arc shape. By combining the elements, it is a so-called split cage that can be divided into a plurality of parts in the circumferential direction. Accordingly, the outer diameter D of the portion where the inner ring 6 is fitted and fixed near the inner end of the hub 4d._Four The outer diameter D of the portion where the first inner ring raceway 11 is formed at the intermediate portion of the hub 4d.₁₁The assembling work of the retainer 65a can be performed regardless of the larger structure. For the inner retainer 65b (or the retainer incorporated in the first to seventh examples described above), it is not necessary to pass a portion having a diameter larger than the inner diameter of the retainer 65b. do not have to.
[0041]
In the case of this example, in order to fix the wheel to the hub 4d, the screw hole 61 is provided in the flange 7 as in the case of the sixth example shown in FIG. In particular, in the case of this example, among the peripheral edge portions at both ends of each screw hole 61, the inner peripheral surface side open peripheral portion of the flange 7 is countersunk so that the tapping of the respective screw holes 61 is facilitated. I can do it. The retaining ring 16a for restraining the inner end face of the inner ring 6 is restrained by an annular retaining ring 54a having an L-shaped cross section. Since the configuration and operation of the other parts are the same as in any of the above-described embodiments, the same parts are denoted by the same reference numerals as those in the drawings describing the embodiments, and redundant description is omitted. Needless to say, the structures of the first to eighth examples described above can be partially extracted and combined as appropriate.
[0042]
The hubs 4a, 4b, 4c, and 4d constituting the wheel rolling bearing unit of the present invention use medium carbon steel of about S53C to S55C, and sequentially perform each process of forging, turning, induction hardening, grinding, and superfinishing. Build by doing. FIG. 7 shows an example of a hardened portion by induction hardening in a diagonal lattice. The retaining groove 15 portion for retaining the retaining ring 16a is subjected to quench hardening for ensuring strength. In addition, the ball groove formed on the inner peripheral surface of the housing portion 10 constituting the constant velocity joint 9 is also subjected to quench hardening for preventing plastic deformation and ensuring a rolling fatigue life. In the example shown in FIG. 7, in order to reduce the plate thickness in order to reduce the weight of the rolling bearing unit for wheels as much as possible, a hardened layer and an inner diameter formed from a part of the housing portion 10 from the outer diameter side of the housing portion 10. The hardened layer formed from the side is continuous. In this case, it is preferable to perform induction hardening from the outer diameter side and induction hardening from the inner diameter side simultaneously. The reason for this is as follows. That is, in order to reduce the plate thickness for weight reduction and ensure sufficient strength, the cured layer formed from the outer diameter side and the cured layer formed from the inner diameter side as described above are connected. The core hardness is preferably Hv500 or more. On the other hand, without performing quenching at the same time, when performing induction hardening from the outer diameter side and induction hardening from the inner diameter side before and after, quenching of the part that has been hardened by quenching first, There is a possibility that the core hardness cannot be secured. Therefore, induction hardening from the outer diameter side and induction hardening from the inner diameter side are performed simultaneously. Further, in order to secure the strength of the base of the flange 7 and to prevent the wear of the surface on which the seal lip of the seal ring 14 slides, these portions are subjected to quench hardening treatment. However, when the surface on which the seal lip of the seal 14 slides and the screw holes 61, 61 formed in the flange 7 are close to each other as in the structure shown in FIG. In order to prevent the portions 61 and 61 from being hardened by quenching, a structure is adopted in which no quenching is performed from the middle of the sliding surface of the seal lip.
[0043]
【The invention's effect】
Since the present invention is configured and operates as described above, it is possible to realize a small and lightweight wheel rolling bearing unit and contribute to the improvement of the performance of the automobile in terms of fuel consumption, riding comfort and the like.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a view of a retaining ring as viewed from the side of FIG.
FIG. 3 is a sectional view showing a second example of the embodiment of the present invention.
FIG. 4 is a sectional view showing the third example.
FIG. 5 is a sectional view showing a fourth example.
FIG. 6 is a sectional view showing the fifth example.
FIG. 7 is a sectional view showing the sixth example.
FIG. 8 is an enlarged view of a part A in FIG.
FIG. 9 is a view similar to FIG. 8 showing an undesirable structure.
FIG. 10 is a view similar to FIG. 8, showing a seventh example of the embodiment of the invention.
FIG. 11 is a sectional view showing the eighth example.
FIG. 12 is a cross-sectional view showing an example of a conventional structure.
[Explanation of symbols]
    1 outer ring
    2 Mounting part
    3, 3a, 3b Outer ring raceway
    4, 4a, 4b, 4c, 4d hub
    5 First inner ring
    6 Second inner ring (inner ring)
    7 Flange
    8 Stud
    9 Constant velocity joint
  10 Housing part
  11 First inner ring raceway
  12 Second inner ring raceway
  13 Rolling elements
  14, 14a Seal ring
  15 Locking groove
  16, 16a Retaining ring
  17 steps
  18, 18a, 18b boots
  19 Retaining band
  20Engaging groove
  21 Drive shaft
  22 inner ring
  23 balls
  24 heads
  25 Meat stealing club
  26 Retaining ring element
  27 Control part
  28 Small diameter cylindrical part
  29 circle part
  30 Large diameter cylindrical part
  31 Metal plate
  32 Thermal insulation layer
  33 Annular space
  34 Slinger
  35, 35a Seal lip
  36 tone wheel
  37 through holes
  38, 38a, 38b sensor
  39 Encoder
  40 Support ring
  41 Encoder body
  42 Cylindrical part
  43 Annulus
  44, 44a Blocking plate
  45 Bulkhead
  46
  47 Inner diameter side cylindrical part
  48 Outer diameter side cylindrical part
  49 Connecting part
  50 Mounting hole
  51 screws
  52 O-ring
  53 Harness
  54, 54a Retaining ring
  55 Holding part
  56 Second cover plate
  57 Buttocks
  58 Retaining ring
  59 Cylindrical part
  60 torus
  61 Screw hole
  62 Core
  63 Seal Lip
  64 Slinger
  65a, 65b Cage

Claims

Mounting portion for supporting the suspension system on an outer peripheral surface (2), the outer ring raceway of the double row inner circumferential surface (3a, 3b), an outer ring (1) having each, the outer ring at one end portion close to the outer peripheral surface A flange (7) for supporting and fixing the wheel is formed on the portion protruding in the axial direction from (1), and the first inner ring raceway (11) is provided in the middle portion, and the other end portion is connected to the constant velocity joint. housing portion serving as the outer ring (10) and the hub (4 a to 4 d), the outer peripheral surface to form a second inner ring raceway (12), the first of the intermediate portion of the hub (4 a to 4 d) An inner ring (6) that is externally fitted and fixed to a portion closer to the other end than the portion where the inner ring raceway (11) is formed, the double row outer ring raceways (3a, 3b), and the first and second inner ring raceways (11 , 12, respectively by providing rollably by a plurality between), of the outer ring (1) Middle portion of the hub (4 a to 4 d) and the inner ring and a plurality of rolling elements rotatably supporting the (6) (13), one end portion inner peripheral surface of the outer ring (1) and the hub (4 a to 4 d) to In a rolling bearing unit for a wheel provided with a seal ring (14) for closing an annular gap with an outer peripheral surface, the flange (7) and the housing part (10) are connected to the hub (4a to 4d). are integrally formed, the first inner ring raceway (11) as well as directly formed in the intermediate portion outer peripheral surface of the hub (4 a to 4 d), of the intermediate portion outer peripheral surface of the hub (4 a to 4 d), The outer diameter of the portion between the first inner ring raceway (11) and the inner surface of the base end portion of the flange (7) where the seal ring (14) is disposed is defined as the inner ring (6). and greater than the outer diameter of the externally secured portion of said first inner ring Road (11) a plurality of rolling elements that constitute the pitch circle diameter, the rolling element row relating to the second inner ring raceway (12) of the plurality of rolling elements constituting the rolling element row (13) about (13) Rolling bearing unit for wheels , characterized by being smaller than the pitch circle diameter.

The inner ring is prevented from moving to the other end side in the axial direction by a retaining ring locked in a locking groove formed on a part of the outer peripheral surface of the hub that is exposed to the other end side of the hub from the end surface of the inner ring. The rolling bearing unit for a wheel according to claim 1.

The retaining ring is configured by combining a plurality of retaining ring elements each having an arc shape, and engaging each inner peripheral edge with a locking groove in a state of being combined in an annular shape. Around each of the above-described retaining ring elements, a retaining ring is provided to prevent the retaining ring elements from being displaced in the diametrically outward direction. And a part of the boot is close to or in contact with the axial end edge of the restraining ring, and the end surface of the inner ring existing on both sides in the axial direction of the restraining ring and a part of the boot The rolling bearing unit for a wheel according to claim 2, wherein the retaining ring prevents the retaining ring from being detached from the periphery of each retaining ring element.

A plurality of rolling elements provided between the first inner ring raceway and the outer ring raceway facing the first inner ring raceway are held by a cage so as to be freely rollable. The rolling bearing unit for a wheel according to any one of claims 1 to 3, wherein the roller bearing unit is formed so as to be divided into a plurality of parts along a circumferential direction by combining the formed cage elements.