【０００１】
【発明の属する技術分野】
本発明は、自動車等の駆動車輪を支持する駆動車輪用軸受装置に関するもので、特に、ハブ輪と等速自在継手と複列の転がり軸受とをユニット化した駆動車輪用軸受装置に関する。
【０００２】
【従来の技術】
ＦＲ車の後輪、ＦＦ車の前輪、あるいは４ＷＤ車の全輪といった自動車の駆動輪は、駆動車輪用軸受装置により懸架装置に支持する。近年、駆動車輪用軸受装置は軽量・コンパクト化を狙って、ハブ輪と等速自在継手と軸受部とをユニット化する傾向にある。
【０００３】
図９は従来の駆動車輪用軸受装置を示す縦断面図で、ハブ輪５０と、複列の転がり軸受６０と、等速自在継手７０とをユニット化して構成している。ハブ輪５０は車輪（図示せず）を取り付けるための車輪取付フランジ５１を一体に有し、この車輪取付フランジ５１の円周等配位置には車輪を固定するためのハブボルト５２を植設している。
【０００４】
複列の転がり軸受６０は外方部材６１と内方部材６２と複列の転動体６３、６３とからなり、外方部材６１は外周に車体（図示せず）に取り付けるための車体取付フランジ６４を一体に有し、内周には複列の外側転走面６１ａ、６１ａを形成している。一方、内方部材６２は、前記した外方部材６１の外側転走面６１ａ、６１ａに対向する複列の内側転走面５０ａ、７１ａを形成している。この一方の内側転走面５０ａはハブ輪５０の外周に一体形成し、他方の内側転走面７１ａは等速自在継手７０の外側継手部材７１の外周に一体形成している。複列の転動体６３、６３をこれら転走面６１ａ、５０ａと６１ａ、７１ａ間にそれぞれ収容し、保持器６５、６５で転動自在に保持している。この場合、内方部材６２はハブ輪５０と外側継手部材７１を指す。軸受部６０の端部にはシール６６、６７を装着し、軸受内部に封入した潤滑グリースの漏洩と、外部からの雨水やダスト等の侵入を防止している。
【０００５】
等速自在継手７０は外側継手部材７１と図示しない継手内輪、ケージ、およびトルク伝達ボールとからなる。外側継手部材７１はカップ状のマウス部７２と、このマウス部７２から軸方向に延びる軸部７３を有し、マウス部７２の内周には軸方向に延びる曲線状のトラック溝７２ａを形成している。
【０００６】
中空に形成した外側継手部材７１の軸部７３をハブ輪５０に内嵌すると共に、ハブ輪５０の内周面に凹凸部５３を形成し、軸部７３を拡径してこの凹凸部５３に食い込ませ、その嵌合部を加締めてハブ輪５０と外側継手部材７１とを塑性結合させている（特開２００１−１８６０５号公報参照）。
【０００７】
前記の駆動車輪用軸受装置では、従来のセレーション等のトルク伝達手段に比べ嵌合部の緩みを防止でき、かつ嵌合部の摩耗を抑制することができるため、装置の耐久性と操縦安定性を向上させることができる。また、この結合部はトルク伝達手段と、ハブ輪と外側継手部材の結合手段とを併せ持つため、一層の軽量・コンパクト化に寄与する。
【０００８】
しかし、こうした駆動車輪用軸受装置において、車輪を取付けるハブ輪５０と外側継手部材７１とを塑性結合する手段を採用しているため、製品の結合状況を非破壊方式で確認することは難しく、結合部の強度や耐久性に対する品質保証は、製品の抜取り検査による破壊検査に委ねていた。結合部の品質はハブ輪５０、すなわち車輪の脱落に直結するため、フェールセーフの観点でそのさらなる信頼性の向上が望まれていた。
【０００９】
この問題を解決するため、本出願人は図８に示す駆動車輪用軸受装置を既に提案している（特願２００１−２８２６４７号参照）。この駆動車輪用軸受装置は、ハブ輪５０’と外側継手部材７１’の嵌合部で、外径側に配設した部材（ここではハブ輪５０’）に硬化させた凹凸部５３を形成すると共に、この凹凸部５３に、内径側に配設した部材（ここでは外側継手部材７１’）を拡径させて食い込ませることにより、ハブ輪５０’と外側継手部材７１’とを塑性結合して一体化し、さらに、内径側に配設した部材７１’の端部を径方向外方に塑性変形させて加締部７４とし、この加締部７４により両部材５０’、７１’を軸方向に固定したものである。
【００１０】
【発明が解決しようとする課題】
しかし、駆動車輪用軸受装置において、こうした加締部をはじめ、止め輪等の結合手段を付加することは、ハブ輪５０’と外側継手部材７１’とを塑性結合をする工程に加え、さらに加締工程、あるいは止め輪装着工程等の工程が必要となる。これでは工数が嵩んでコストの高騰を招来することになる。最近は、こうした車輪用軸受装置において、軽量コンパクト化は無論のこと、その品質と信頼性向上に加え、低コスト化への要求は厳しいものがある。
【００１１】
本発明は、このような事情に鑑みてなされたもので、大きなモーメント荷重が装置に作用しても結合部に緩みが発生せず、簡単な構成で引抜き耐力の増大を図った駆動車輪用軸受装置を提供することを目的としている。
【００１２】
【課題を解決するための手段】
係る目的を達成すべく、本発明のうち請求項１記載の発明は、ハブ輪と等速自在継手と複列の転がり軸受とをユニット化し、前記ハブ輪と前記等速自在継手の外側継手部材とを嵌合させ、前記複列の転がり軸受における内側転走面のうち少なくとも一方の内側転走面を前記ハブ輪に有し、このハブ輪と前記外側継手部材の嵌合部で、外径側に配設した部材に硬化させた凹凸部を形成すると共に、この凹凸部に、内径側に配設した部材を拡径させて食い込ませ、前記ハブ輪と外側継手部材とを塑性結合により一体化した駆動車輪用軸受装置において、前記凹凸部を一部除去して所定の環状凹所を形成し、この環状凹所内に前記内径側に配設した部材の一部を膨出させた。
【００１３】
このように、凹凸部に環状凹所を形成し、この環状凹所内に内径側に配設した部材を拡径して膨出させたので、この部分の嵌合部は凹凸部によって拘束されずより大きく拡径される。したがって、簡単な構成でハブ輪と外側継手部材の引抜き耐力が増大する。
【００１４】
好ましくは、請求項２に記載の発明のように、前記環状凹所を、前記凹凸部のうち拡径範囲の中央部を除く少なくとも一方の端部に形成すれば、拡径力が強固な中央部を避け、比較的拡径力が低い端部にて引抜き耐力を増大させることができ、結合部のトルク伝達容量の減少を最小限に止めることができる。
【００１５】
また、請求項３に記載の発明は、ハブ輪と等速自在継手と複列の転がり軸受とをユニット化し、前記ハブ輪と前記等速自在継手の外側継手部材とを嵌合させ、前記複列の転がり軸受における内側転走面のうち少なくとも一方の内側転走面を前記ハブ輪に有し、このハブ輪と前記外側継手部材の嵌合部で、外径側に配設した部材に硬化させた凹凸部を形成すると共に、この凹凸部に、内径側に配設した部材を拡径させて食い込ませ、前記ハブ輪と外側継手部材とを塑性結合により一体化した駆動車輪用軸受装置において、前記凹凸部の端面を一部除去して所定の環状凹所を形成し、この環状凹所内に前記内径側に配設した部材の一部を膨出させた。
【００１６】
このように、凹凸部の端面に環状凹所を形成し、この環状凹所内に内径側に配設した部材を拡径して膨出させたので、この膨出部のせん断力によってハブ輪と外側継手部材の引抜き耐力が増大する。
【００１７】
また、請求項４に記載の発明のように、前記凹凸部を、独立した複数の環状溝と複数の軸方向溝とを略直交させて形成した交叉溝で構成すれば、結合部のトルク伝達容量と引抜き耐力を効果的に増大させることができる。
【００１８】
好ましくは、請求項５に記載の発明のように、前記環状凹所を、拡径範囲の一端側から前記環状溝の山ピッチに対して０．５〜３．０倍の範囲に形成すれば、凹凸部を形成した部材、例えばハブ輪におけるせん断強度も充分確保でき、かつ、結合部のトルク伝達容量の減少を抑えて所望の引抜き耐力の増大を図ることができる。
【００１９】
さらに、請求項６に記載の発明のように、前記環状凹所の軸方向寸法を、前記環状溝の山ピッチに対して０．５〜３．０倍の範囲に形成すれば、環状凹所の加工が容易にでき、この環状凹所に埋没した膨出部におけるせん断面の面積が充分確保できて引抜き耐力の増大を図ることができると共に、結合部のトルク伝達容量の減少を抑えることができる。
【００２０】
また、請求項７に記載の発明のように、前記環状凹所の底径を、前記環状溝の溝底径または前記軸方向溝の溝底径に対して１．０１〜１．２０倍の範囲に形成すれば、凹凸部を形成した部材、例えばハブ輪の強度を充分確保でき、かつ、引抜き耐力の増大を図ることができる。
【００２１】
さらに、請求項８に記載の発明のように、前記嵌合部の拡径後の外径を、前記環状溝の溝底径または前記軸方向溝の溝底径に対して１．０１〜１．１５倍の範囲に設定すれば、結合部のトルク伝達容量や引抜き耐力等の強度面、および拡径部の材料の延性、さらには加工性や加工治具の寿命等を考慮した最適な拡径量を得ることができる。
【００２２】
好ましくは、請求項９に記載の発明のように、前記ハブ輪に前記等速自在継手の外側継手部材を内嵌させ、前記複列の転がり軸受における内側転走面のうち一方の内側転走面を前記ハブ輪に形成すると共に、他方の内側転走面を前記外側継手部材に形成した、所謂第４世代構造にあっては、可及的に装置の軽量・コンパクト化を図ることができると共に、結合部のトルク伝達容量を抑え、かつ、引抜き耐力の増大を図ることができる。
【００２３】
また、請求項１０に記載の発明は、前記複列の転がり軸受のうち、インボード側の軸受の負荷容量をアウトボード側よりも高く設定した。これにより、左右の軸受の寿命バランスを図ることができ、装置の耐久性を実質的に向上させることができる。
【００２４】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて詳細に説明する。図１は、本発明に係る駆動車輪用軸受装置の第１の実施形態を示す縦断面図である。この駆動車輪用軸受装置は、ハブ輪１と、複列の転がり軸受２と、等速自在継手３とをユニット化して構成している。なお、以下の説明では、車両に組み付けた状態で、車両の外側寄り（図面左側）となる側をアウトボード側、中央寄り側（図面右側）をインボード側という。
【００２５】
ハブ輪１は、アウトボード側の端部に車輪（図示せず）を取り付けるための車輪取付フランジ４を一体に有している。ハブ輪１の内周面には凹凸部５を形成し、熱処理によって表面硬さを５４〜６４ＨＲＣの範囲に硬化層１０を形成する（図中散点模様にて示す）。熱処理としては、局部加熱ができ、硬化層深さの設定が比較的容易にできる高周波誘導加熱による焼入れが好適である。
【００２６】
なお、凹凸部５は、図２に示すような複数列の溝を直交させた形状を例示することができる。（ａ）は互いに傾斜した溝６で、（ｂ）は軸方向および周方向の溝６’でアヤメローレット状を形成することができる。また、凹凸部５の凸部は良好な食い込み性を確保するために、三角形状等の尖端形状に形成する。ここでは、旋削等により独立して形成した複数の環状溝６ａと、ブローチ加工等により形成した複数の軸方向溝６ｂとを略直交させた交叉溝６’としている。
【００２７】
複列の転がり軸受２は、外方部材７と内方部材８と複列の転動体９、９とを備えている。外方部材７は外周に車体（図示せず）に取り付けるための車体取付フランジ７ａを一体に有し、内周には複列の外側転走面７ｂ、７ｂを形成している。一方、内方部材８は、ハブ輪１と後述する外側継手部材１４を指し、外方部材７の外側転走面７ｂ、７ｂに対向するアウトボード側の内側転走面１ａをハブ輪１の外周に、またインボード側の内側転走面１４ａを外側継手部材１４の外周にそれぞれ形成している。複列の転動体９、９をこれら転走面７ｂ、１ａと７ｂ、１４ａ間にそれぞれ収容し、保持器１１、１１で転動自在に保持している。複列の転がり軸受２の端部にはシール１２、１３を装着し、軸受内部に封入した潤滑グリースの漏洩と、外部からの雨水やダスト等の侵入を防止している。ハブ輪１の外周において、シール１２のシールリップが摺接するシールランド部、内側転走面１ａ、および外側継手部材１４の肩部１６と当接するインロウ部１ｂの表面に高周波焼入れによって硬化層１０’を形成している（図中散点模様にて示す）。ここで複列の転がり軸受２は転動体９、９をボールとした複列アンギュラ玉軸受を例示したが、これに限らず転動体に円すいころを使用した複列円すいころ軸受であっても良い。
【００２８】
また、この種の駆動車輪用軸受装置においては、複列の転がり軸受２のうち、インボード側は相対的に大きなモーメント荷重を負荷することになる。この左右の転動疲労寿命のバランスを図るため、本実施形態では、複列の転動体９、９のＰＣＤ（ピッチ円直径）を、アウトボード側とインボード側とで異ならせ、相対的に大きなモーメント荷重を負荷するインボード側のＰＣＤをアウトボード側よりも若干大径に設定して負荷容量の増大を図っている。これ以外にも、インボード側の転動体９の個数やサイズを変更し、インボード側軸受の負荷容量の増大を図るようにしても良い。
【００２９】
等速自在継手３は外側継手部材１４と継手内輪１５、ケージ１７、およびトルク伝達ボール１８とからなる。外側継手部材１４はカップ状のマウス部１９と、このマウス部１９の底部をなす肩部１６と、この肩部１６から軸方向に延びる軸部２０を有し、マウス部１９の内周には軸方向に延びる曲線状のトラック溝１９ａを形成している。
【００３０】
中空に形成した外側継手部材１４の肩部１６の外周には前記した内側転走面１４ａを形成している。また、軸部２０はハブ輪１のインロウ部１ｂを圧入する小径段部２０ａと、ハブ輪１と嵌合する嵌合部２０ｂを有している。小径段部２０ａに圧入したハブ輪１のインロウ部１ｂを肩部１６によって突合せ状態で、嵌合部２０ｂをハブ輪１に内嵌すると共に、この嵌合部２０ｂの内径にマンドレルを挿入・抜脱させる等、嵌合部２０ｂを適宜な手段で拡径してハブ輪１の凹凸部５に食い込ませ、この嵌合部２０ｂを加締めてハブ輪１と外側継手部材１４とを塑性結合させる。これにより、この結合部はトルク伝達手段と、ハブ輪１と外側継手部材１４の結合手段とを併せ持つため、従来のセレーション等のトルク伝達手段をハブ輪１や外側継手部材１４に形成する必要はなく、装置の軽量・コンパクト化を実現することができる。
【００３１】
外側継手部材１４において、マウス部１９の内周に形成したトラック溝１９ａとシール１３が摺接するシールランド部から内側転走面１４ａ、および小径段部２０ａに亙って表面硬化処理を施す。硬化処理として高周波誘導加熱による焼入れが好適である。また、拡径する嵌合部２０ｂは、鍛造後の素材表面硬さ２４ＨＲＣ以下の未焼入れ部とし、前記したハブ輪１の凹凸部５の表面硬さ５４〜６４ＨＲＣとの硬度差を３０ＨＲＣ以上に設定するのが好ましい。これにより、嵌合部２０ｂが凹凸部５に容易に、かつ深く食い込み、凹凸部５の先端が潰れることなく強固に両者を塑性結合することができる。なお、中空状の外側継手部材１４の内径にエンドキャップ１９ｂを装着して、マウス部１９に封入された潤滑グリースの外部への漏洩と外部からのダスト侵入を防止している。
【００３２】
前述したように、ハブ輪１の内周面には凹凸部５を形成しているが、この部５の範囲は、車輪取付フランジ４を挟んで、車輪のパイロット部１ｃからアウトボード側の転動体９の作用線（転動体９と内側転走面１ａとの接触点と、転動体９の中心とを結んだ線を延長した線）の近傍までとしている。この凹凸部５のアウトボード側には環状凹所２１を形成している。すなわち、図３（ａ）に示すように、この環状凹所２１は、拡径範囲Ｌのアウトボード側端部に形成している。軸部２０の嵌合部２０ｂを拡径することにより、この嵌合部２０ｂの外径部が凹凸部５に食込む訳であるが、凹凸部５の一部をこのように除去して環状凹所２１を形成することにより、この部分の嵌合部２０ｂは拘束されずより大きく拡径される。したがって、軸方向の引抜き耐力が増大することになる。
【００３３】
本出願人が実施した拡径試験において、拡径範囲Ｌの中でも中央部が最も深く凹凸部５に食込んでいることが判った。これは図４に示す嵌合部２０ｂの内径表面形状を見ても推察できる。よって、中央部に環状凹所２１を形成することは引抜き耐力を増大させる反面、結合部のトルク伝達容量を減少させることになり好ましくない。したがって、引抜き耐力を増大させる環状凹所２１は、軸方向いかなる部位でも同等であるため、本実施形態では、トルク伝達容量の減少を最小限に止めることができる拡径範囲Ｌの端部、実際には拡径範囲Ｌのアウトボード側から環状溝６ａの山ピッチｔ０に対して０．５〜３．０倍の範囲に形成している。環状凹所２１をこれ以上アウトボード側に形成するとハブ輪１側のせん断強度が小さくなり、所望の引抜き耐力が望めない。また、環状凹所２１をこれ以上インボード側に移行させると結合部のトルク伝達容量が大きく減少して好ましくない。
【００３４】
図３（ａ）において、環状凹所２１の幅寸法ｔ１は、独立した環状溝６ａの山ピッチｔ０に対して０．５〜３．０倍の範囲に形成している。また、環状凹所２１の底径ｄ５は、環状溝６ａの溝底径ｄ４、または図３（ｂ）に示す軸方向溝６ｂの溝底径ｄ３に対して１．０１〜１．２０倍の範囲に形成している。
【００３５】
ここで、環状凹所２１の幅寸法ｔ１を、環状溝６ａの山ピッチｔ０の０．５倍以下に設定すると加工が難しくなるばかりでなく、この環状凹所２１に埋没した膨出部におけるせん断面の面積が小さくなり、引抜き耐力の増大が見込めない。一方、山ピッチｔ０の３．０倍以上に設定すると、結合部のトルク伝達容量が大きく減少して拡径範囲Ｌを拡大せざるを得なくなる。拡径範囲Ｌの拡大は装置の重量増加につながり好ましくない。
【００３６】
また、環状凹所２１の底径ｄ５を、環状溝６ａの溝底径ｄ４、または軸方向溝６ｂの溝底径ｄ３に対して１．０１〜１．２０倍の範囲に設定したのは、外側継手部材１４の材質に依存している。例えばＳ５３Ｃの伸びの保証最小値は１５％であるから、１．２０倍が適当である。したがって、１．２０倍以上に設定しても引抜き耐力には寄与せず、かえってハブ輪１の強度を低下させることになり好ましくない。
【００３７】
ここで、嵌合部２０ｂの拡径量について説明する。前述したように、嵌合部２０ｂの内径にマンドレルを挿入・抜脱させる等、嵌合部２０ｂを適宜な手段で拡径してハブ輪１の凹凸部５に食い込ませる訳であるが、結合部のトルク伝達容量や引抜き耐力等の強度面、および材料の延性、さらには加工性や加工治具の寿命等を鑑みて拡径量、すなわち、ハブ輪１の凹凸部５の内径、嵌合部２０ｂの内径、およびマンドレル等の拡径治具の外径を決定する。本実施形態では、図３に示すように、拡径後、嵌合部２０ｂの外径ｄ２は、環状溝６ａの溝底径ｄ４または軸方向溝６ｂの溝底径ｄ３に対して１．０１〜１．１５倍の範囲になるように設定している。なお、環状凹所２１の形状は矩形に限らず、図５（ａ）に示す三角形状の環状凹所２１’や、図５（ｂ）に示すような半円形状の環状凹所２１”であっても良い。
【００３８】
なお、本実施形態では、複列の転がり軸受２の内側転走面１ａをハブ輪１の外周面と外側継手部材１４の外周面に直接形成した、所謂第４世代構造を例示したが、これに限らず、装置のアウトボード側にハブ輪と外側継手部材の塑性結合部を有する構造であれば、従来の第１〜３世代構造であっても良い。すなわち、それぞれの構造の特徴を損なうことなく、車両旋回時、装置に曲げモーメント荷重が負荷され、塑性結合部を含む外側継手部材の軸部が曲げられて繰返し応力が発生しても結合部の緩みを防止することができると共に、塑性結合部のトルク伝達容量の減少を抑え、かつ、簡単な構成で引抜き耐力の増大を図ることができる。
【００３９】
図６（ａ）は本発明に係る駆動車輪用軸受装置の第２の実施形態を示す要部断面図、（ｂ）はその側面図である。ここでは、ハブ輪１’の内周面に凹凸部５を形成すると共に、このアウトボード側に環状凹所２１を形成している。前述した第１の実施形態と異なる点は、図３に示した環状凹所２１に加え、拡径範囲Ｌのインボード側端部にも環状凹所２１を形成している点のみで、その他同一部品同一部位には同じ符号を付してその説明を省略する。このように、拡径範囲Ｌの両端部に環状凹所２１を形成することにより、結合部のトルク伝達容量の減少を抑え、一層引抜き耐力を増大することができる。なお、環状凹所２１の位置および寸法等の仕様は、前述した第１の実施形態と同様である。
【００４０】
図７（ａ）は本発明に係る駆動車輪用軸受装置の第３の実施形態を示す要部断面図、（ｂ）はその側面図である。前述した実施形態と異なる点はハブ輪の構成のみで、その他同一部品同一部位には同じ符号を付してその詳細な説明を省略する。
【００４１】
ハブ輪２２の内周面には硬化させた凹凸部５を形成すると共に、外側継手部材１４における軸部２０の嵌合部２０ｂをこの凹凸部５に食込ませ、ハブ輪２２と外側継手部材１４を塑性結合している。凹凸部５の範囲は前述した実施形態と同様、車輪取付フランジ４を挟んで、車輪パイロット部２２ａからアウトボード側の転動体（図示せず）の作用線の近傍までとしている。ここで、ハブ輪２２のアウトボード側端面を座ぐりし、環状凹所２３を形成している。ここで、軸部２０の嵌合部２０ｂを拡径することにより、この嵌合部２０ｂの外径部が凹凸部５に食込む訳であるが、凹凸部５の一部をこのように除去して環状凹所２３を形成することにより、この部分の嵌合部２０ｂは拘束されずより大きく拡径される。したがって、この環状凹所２３内の膨出部によって軸方向の引抜き耐力が増大することになる。
【００４２】
図７（ａ）において、環状凹所２３の深さ、すなわち嵌合部２０ｂの端面２０ｃからの寸法ｔ２は、独立した環状溝６ａの山ピッチｔ０に対して、０．５〜３．０倍の範囲に形成している。また、環状凹所２３の底径ｄ５は、環状溝６ａの溝底径ｄ４、または図７（ｂ）に示す軸方向溝６ｂの溝底径ｄ３以上、ハブ輪２２におけるパイロット部２２ａの外径Ｄ１より１ｍｍ小径に、すなわちＤ１−１に形成している。
【００４３】
ここで、環状凹所２３の深さｔ２を、環状溝６ａの山ピッチｔ０の０．５倍以下に設定すると、この環状凹所２３内に膨出した部分のせん断面の面積が小さくなり、引抜き耐力の増大が見込めない。一方、山ピッチｔ０の３．０倍以上に設定すると、結合部のトルク伝達容量が大きく減少して好ましくない。
【００４４】
また、環状凹所２３の底径ｄ５をＤ１−１以下に設定したのは、パイロット部２２ａの強度と加工性の面からである。したがって、これに限らず、前述した実施形態の環状凹所２１と同様、環状溝６ａの溝底径ｄ４または軸方向溝６ｂの溝底径ｄ３に対して１．０１〜１．２０倍の範囲に設定しても良い。
【００４５】
さらに嵌合部２０ｂの拡径量についても前述した実施形態と同様、結合部のトルク伝達容量や引抜き耐力等の強度面、および材料の延性、さらには加工性や加工治具の寿命等を鑑み、ハブ輪１の凹凸部５の内径、嵌合部２０ｂの内径、およびマンドレル等の拡径治具の外径を決定している。すなわち、拡径後、嵌合部２０ｂの外径ｄ２は、環状溝６ａの溝底径ｄ４または軸方向溝６ｂの溝底径ｄ３に対して１．０１〜１．１５倍の範囲になるように設定している。
【００４６】
以上、本発明の実施の形態について説明を行ったが、本発明はこうした実施の形態に何等限定されるものではなく、あくまで例示であって、本発明の要旨を逸脱しない範囲内において、さらに種々なる形態で実施し得ることは勿論のことであり、本発明の範囲は、特許請求の範囲の記載によって示され、さらに特許請求の範囲に記載の均等の意味、および範囲内のすべての変更を含む。
【００４７】
【発明の効果】
以上詳述したように、本発明に係る駆動車輪用軸受装置は、ハブ輪と等速自在継手と複列の転がり軸受とをユニット化し、前記ハブ輪と前記等速自在継手の外側継手部材とを嵌合させ、前記複列の転がり軸受における内側転走面のうち少なくとも一方の内側転走面を前記ハブ輪に有し、このハブ輪と前記外側継手部材の嵌合部で、外径側に配設した部材に硬化させた凹凸部を形成すると共に、この凹凸部に、内径側に配設した部材を拡径させて食い込ませ、前記ハブ輪と外側継手部材とを塑性結合により一体化した駆動車輪用軸受装置において、前記凹凸部を一部除去して所定の環状凹所を形成し、この環状凹所内に前記内径側に配設した部材の一部を膨出させたので、この部分の嵌合部は凹凸部によって拘束されずより大きく拡径される。したがって、簡単な構成でハブ輪と外側継手部材の引抜き耐力が増大する。
【図面の簡単な説明】
【図１】本発明に係る駆動車輪用軸受装置の第１の実施形態を示す縦断面図である。
【図２】（ａ）は、本発明に係るハブ輪の凹凸部形状を示す縦断面図で、互いに傾斜し
た螺旋溝で構成したアヤメローレット形状を示す。
（ｂ）は同上、軸方向溝と独立した環状溝との交叉溝で構成したアヤメローレ
ット形状を示す。
【図３】（ａ）は、本発明に係る駆動車輪用軸受装置における第１の実施形態を示す要
部断面図である。
（ｂ）は、同上側面図である。
【図４】本発明に係る駆動車輪用軸受装置における塑性結合部の説明図である。
【図５】（ａ）は、本発明に係る環状凹所の他の実施形態を示す要部拡大図である。
（ｂ）は、同上さらに他の実施形態を示す要部拡大図である。
【図６】（ａ）は、本発明に係る駆動車輪用軸受装置の第２の実施形態を示す要部断面
図である。
（ｂ）は、同上側面図である。
【図７】（ａ）は、本発明に係る駆動車輪用軸受装置の第３の実施形態を示す要部断面
図である。
（ｂ）は、同上側面図である。
【図８】従来の駆動車輪用軸受装置を示す縦断面図である。
【図９】同上
【符号の説明】
１、１’、２２・・・ハブ輪
１ａ、１４ａ・・・・内側転走面
１ｂ・・・・・・・・インロウ部
１ｃ、２２ａ・・・・パイロット部
２・・・・・・・・・複列の転がり軸受
３・・・・・・・・・等速自在継手
４・・・・・・・・・車輪取付フランジ
５・・・・・・・・・凹凸部
６、６’・・・・・・溝
６ａ・・・・・・・・環状溝
６ｂ・・・・・・・・軸方向溝
７・・・・・・・・・外方部材
７ａ・・・・・・・・車体取付フランジ
７ｂ・・・・・・・・外側転走面
８・・・・・・・・・内方部材
９・・・・・・・・・転動体
１０、１０’・・・・硬化層
１１・・・・・・・・保持器
１２、１３・・・・・シール
１４・・・・・・・・外側継手部材
１５・・・・・・・・継手内輪
１６・・・・・・・・肩部
１７・・・・・・・・ケージ
１８・・・・・・・・トルク伝達ボール
１９・・・・・・・・マウス部
１９ａ・・・・・・・トラック溝
１９ｂ・・・・・・・エンドキャップ
２０・・・・・・・・軸部
２０ａ・・・・・・・小径段部
２０ｂ・・・・・・・嵌合部
２０ｃ・・・・・・・嵌合部の端面
２１、２３・・・・・環状凹所
２１’、２１”・・・・環状凹所
５０、５０’・・・・ハブ輪
５０ａ、７１ａ・・・内側転走面
５１・・・・・・・・車輪取付フランジ
５２・・・・・・・・ハブボルト
５３・・・・・・・・凹凸部
６０・・・・・・・・複列の転がり軸受
６１・・・・・・・・外方部材
６１ａ・・・・・・・外側転走面
６２・・・・・・・・内方部材
６３・・・・・・・・転動体
６４・・・・・・・・車体取付フランジ
６５・・・・・・・・保持器
６６、６７・・・・・シール
７０、７０’・・・・等速自在継手
７１、７１’・・・・外側継手部材
７２・・・・・・・・マウス部
７２ａ・・・・・・・トラック溝
７３・・・・・・・・軸部
７４・・・・・・・・加締部
ｄ２・・・・・・・・嵌合部の外径
ｄ３・・・・・・・・軸方向溝の溝底径
ｄ４・・・・・・・・環状溝の溝底径
ｄ５・・・・・・・・環状凹所の底径
Ｄ１・・・・・・・・パイロット部の外径
Ｌ・・・・・・・・・拡径範囲
ｔ０・・・・・・・・環状溝の山ピッチ
ｔ１・・・・・・・・環状凹所の幅寸法
ｔ２・・・・・・・・環状凹所の深さ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a drive wheel bearing device for supporting a drive wheel of an automobile or the like, and more particularly to a drive wheel bearing device in which a hub wheel, a constant velocity universal joint, and a double row rolling bearing are unitized.
[0002]
[Prior art]
The driving wheels of the vehicle, such as the rear wheels of an FR vehicle, the front wheels of an FF vehicle, or all the wheels of a 4WD vehicle, are supported on a suspension device by a driving wheel bearing device. 2. Description of the Related Art In recent years, there has been a trend toward unitizing a hub wheel, a constant velocity universal joint, and a bearing unit for a drive wheel bearing device in order to reduce its weight and size.
[0003]
FIG. 9 is a longitudinal sectional view showing a conventional drive wheel bearing device, in which a hub wheel 50, a double-row rolling bearing 60, and a constant velocity universal joint 70 are unitized. The hub wheel 50 integrally has a wheel mounting flange 51 for mounting a wheel (not shown), and hub bolts 52 for fixing the wheel are implanted at circumferentially equal positions of the wheel mounting flange 51. I have.
[0004]
The double-row rolling bearing 60 includes an outer member 61, an inner member 62, and double-row rolling elements 63, 63. The outer member 61 has a vehicle body mounting flange 64 on its outer periphery for mounting to a vehicle body (not shown). And a double row of outer rolling surfaces 61a, 61a are formed on the inner periphery. On the other hand, the inner member 62 forms multiple rows of inner rolling surfaces 50a, 71a facing the outer rolling surfaces 61a, 61a of the outer member 61 described above. The one inner rolling surface 50a is formed integrally with the outer periphery of the hub wheel 50, and the other inner rolling surface 71a is formed integrally with the outer periphery of the outer joint member 71 of the constant velocity universal joint 70. The double-row rolling elements 63, 63 are accommodated between these rolling surfaces 61a, 50a and 61a, 71a, respectively, and are rotatably held by retainers 65, 65. In this case, the inner member 62 indicates the hub wheel 50 and the outer joint member 71. Seals 66 and 67 are attached to the end of the bearing portion 60 to prevent leakage of lubricating grease sealed inside the bearing and intrusion of rainwater and dust from the outside.
[0005]
The constant velocity universal joint 70 includes an outer joint member 71, a joint inner ring (not shown), a cage, and a torque transmitting ball. The outer joint member 71 has a cup-shaped mouth portion 72 and a shaft portion 73 extending in the axial direction from the mouth portion 72, and a curved track groove 72 a extending in the axial direction is formed on the inner periphery of the mouth portion 72. ing.
[0006]
The shaft portion 73 of the hollow outer joint member 71 is fitted inside the hub wheel 50, and the uneven portion 53 is formed on the inner peripheral surface of the hub wheel 50. The hub wheel 50 and the outer joint member 71 are plastically connected by crimping the fitting portion (see JP-A-2001-18605).
[0007]
In the above-described drive wheel bearing device, since the loosening of the fitting portion can be prevented and the wear of the fitting portion can be suppressed as compared with the conventional torque transmitting means such as serration, the durability and the steering stability of the device are improved. Can be improved. Further, since this connecting portion has both the torque transmitting means and the means for connecting the hub wheel and the outer joint member, it contributes to further reduction in weight and size.
[0008]
However, in such a drive wheel bearing device, since means for plastically connecting the hub wheel 50 to which the wheel is mounted and the outer joint member 71 are employed, it is difficult to check the connection state of the products in a non-destructive manner. Quality assurance for the strength and durability of the part was left to the destructive inspection by sampling inspection of the product. Since the quality of the connecting portion is directly linked to the dropping of the hub wheel 50, that is, the wheel, further improvement in reliability is desired from the viewpoint of fail-safe.
[0009]
To solve this problem, the present applicant has already proposed a bearing device for a drive wheel shown in FIG. 8 (see Japanese Patent Application No. 2001-282647). In this drive wheel bearing device, a hardened uneven portion 53 is formed on a member (here, the hub wheel 50 ') disposed on the outer diameter side at a fitting portion between the hub wheel 50' and the outer joint member 71 '. At the same time, the member (here, the outer joint member 71 ′) disposed on the inner diameter side is enlarged and cut into the uneven portion 53, so that the hub wheel 50 ′ and the outer joint member 71 ′ are plastically connected. Then, the end of the member 71 ′ disposed on the inner diameter side is plastically deformed radially outward to form a caulking portion 74, and the two members 50 ′ and 71 ′ are axially moved by the caulking portion 74. It is fixed.
[0010]
[Problems to be solved by the invention]
However, in the drive wheel bearing device, the addition of the connecting means such as the swaged portion and the retaining ring in addition to the step of plastically connecting the hub wheel 50 'and the outer joint member 71' is further added. A step such as a tightening step or a snap ring mounting step is required. In this case, the number of steps is increased and the cost is increased. In recent years, of course, in such wheel bearing devices, demands have been made for not only weight reduction and compactness but also for cost reduction in addition to improvement in quality and reliability.
[0011]
The present invention has been made in view of such circumstances, and even if a large moment load is applied to a device, a loosening does not occur in a joint portion, and a pull-out resistance is increased with a simple configuration by using a drive wheel bearing. It is intended to provide a device.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention provides a hub wheel, a constant velocity universal joint, and a double row rolling bearing as a unit, and an outer joint member of the hub wheel and the constant velocity universal joint. And the hub wheel has at least one inner rolling surface of the inner rolling surfaces in the double row rolling bearing, and a fitting portion between the hub wheel and the outer joint member has an outer diameter. A hardened uneven portion is formed on the member arranged on the side, and the member arranged on the inner diameter side is enlarged and bite into the uneven portion, and the hub wheel and the outer joint member are integrated by plastic coupling. In the bearing device for a drive wheel, the concave and convex portions are partially removed to form a predetermined annular recess, and a part of the member disposed on the inner diameter side is swelled in the annular recess.
[0013]
As described above, since the annular recess is formed in the uneven portion, and the member disposed on the inner diameter side is expanded and swelled in the annular recess, the fitting portion of this portion is not restricted by the uneven portion. The diameter is expanded larger. Therefore, the pull-out strength of the hub wheel and the outer joint member increases with a simple configuration.
[0014]
Preferably, as in the invention according to claim 2, the annular concave portion is formed at at least one end of the uneven portion excluding the central portion of the enlarged diameter range, so that the central force having a large expanding force is provided. The pull-out resistance can be increased at the end where the radial expansion force is relatively low by avoiding the portion, and the decrease in the torque transmission capacity of the coupling portion can be minimized.
[0015]
Further, the invention according to claim 3 is that the hub wheel, the constant velocity universal joint, and the double row rolling bearing are unitized, and the hub wheel and the outer joint member of the constant velocity universal joint are fitted to each other, At least one of the inner rolling surfaces of the rolling bearings in the row has an inner rolling surface on the hub wheel, and at a fitting portion between the hub wheel and the outer joint member, a member disposed on the outer diameter side is hardened. In the bearing device for a drive wheel, the member provided on the inner diameter side is enlarged and bite into the uneven portion, and the hub wheel and the outer joint member are integrated by plastic coupling. Then, a predetermined annular recess was formed by partially removing the end face of the uneven portion, and a part of the member disposed on the inner diameter side was swelled in the annular recess.
[0016]
As described above, the annular recess is formed on the end surface of the uneven portion, and the member disposed on the inner diameter side is expanded and swelled in the annular recess. The pull-out strength of the outer joint member increases.
[0017]
Further, according to the invention as set forth in claim 4, if the uneven portion is formed by a cross groove formed by making a plurality of independent annular grooves and a plurality of axial grooves substantially orthogonal to each other, the torque transmission of the coupling portion is achieved. The capacity and the pull-out strength can be effectively increased.
[0018]
Preferably, as in the invention according to claim 5, the annular recess is formed in a range of 0.5 to 3.0 times the mountain pitch of the annular groove from one end side of the enlarged diameter range. In addition, it is possible to sufficiently secure the shear strength of a member having an uneven portion, for example, a hub wheel, and increase a desired pull-out resistance by suppressing a decrease in the torque transmission capacity of the joint portion.
[0019]
Further, when the axial dimension of the annular recess is formed in a range of 0.5 to 3.0 times the mountain pitch of the annular groove as in the invention according to claim 6, the annular recess is formed. Can be easily processed, the area of the shearing surface in the bulged portion buried in the annular recess can be sufficiently secured, the pull-out strength can be increased, and the decrease in the torque transmission capacity of the joint portion can be suppressed. it can.
[0020]
Further, as in the invention according to claim 7, the bottom diameter of the annular recess is 1.01 to 1.20 times the groove bottom diameter of the annular groove or the groove bottom diameter of the axial groove. If it is formed in the range, the strength of the member having the concave and convex portions, for example, the hub wheel, can be sufficiently secured, and the pull-out resistance can be increased.
[0021]
Further, as in the invention as set forth in claim 8, the outer diameter of the fitting portion after diameter expansion is 1.01 to 1 with respect to the groove bottom diameter of the annular groove or the groove bottom diameter of the axial groove. If it is set within the range of .15 times, the optimum expansion considering the torque transmission capacity and pull-out strength of the joint, the ductility of the material of the enlarged diameter part, the workability and the service life of the processing jig, etc. The amount of diameter can be obtained.
[0022]
Preferably, as in the invention according to claim 9, the outer joint member of the constant velocity universal joint is fitted inside the hub wheel, and one of the inner rolling surfaces of the double row rolling bearings has an inner rolling surface. In a so-called fourth-generation structure in which a surface is formed on the hub wheel and the other inner rolling surface is formed on the outer joint member, the device can be made as lightweight and compact as possible. At the same time, it is possible to suppress the torque transmission capacity of the coupling portion and increase the pull-out resistance.
[0023]
In the tenth aspect of the present invention, the load capacity of the inboard side bearing is set higher than that of the outboard side bearing among the double row rolling bearings. Thereby, the life balance of the left and right bearings can be balanced, and the durability of the device can be substantially improved.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a first embodiment of a drive wheel bearing device according to the present invention. This bearing device for a drive wheel is configured by unitizing a hub wheel 1, a double-row rolling bearing 2, and a constant velocity universal joint 3. In the following description, the side closer to the outside of the vehicle (left side in the drawing) and the side closer to the center (right side in the drawing) are referred to as the inboard side when assembled to the vehicle.
[0025]
The hub wheel 1 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end on the outboard side. An uneven portion 5 is formed on the inner peripheral surface of the hub wheel 1, and a hardened layer 10 is formed by heat treatment to have a surface hardness in a range of 54 to 64 HRC (shown by dotted patterns in the figure). As the heat treatment, quenching by high-frequency induction heating that can perform local heating and relatively easily set the depth of the hardened layer is preferable.
[0026]
In addition, the uneven | corrugated part 5 can exemplify the shape which made the groove | channel of several rows orthogonal as shown in FIG. (A) is a groove 6 inclined to each other, and (b) is an axial and circumferential groove 6 ′, which can form an iris knurl. In addition, the convex portion of the concave / convex portion 5 is formed in a pointed shape such as a triangular shape in order to secure a good biting property. Here, a plurality of annular grooves 6a independently formed by turning or the like and a plurality of axial grooves 6b formed by broaching or the like are crossed grooves 6 'which are substantially orthogonal to each other.
[0027]
The double-row rolling bearing 2 includes an outer member 7, an inner member 8, and double-row rolling elements 9, 9. The outer member 7 integrally has a vehicle body mounting flange 7a for mounting to a vehicle body (not shown) on the outer periphery, and double-row outer rolling surfaces 7b, 7b on the inner periphery. On the other hand, the inner member 8 refers to the hub wheel 1 and an outer joint member 14 described later, and the inner rolling surface 1a on the outboard side facing the outer rolling surfaces 7b, 7b of the outer member 7 The inner rolling surface 14 a on the inboard side is formed on the outer periphery of the outer joint member 14, respectively. Double row rolling elements 9, 9 are accommodated between these rolling surfaces 7b, 1a and 7b, 14a, respectively, and are held rotatably by retainers 11, 11. Seals 12 and 13 are attached to the ends of the double row rolling bearing 2 to prevent leakage of lubricating grease sealed inside the bearing and intrusion of rainwater and dust from the outside. On the outer periphery of the hub wheel 1, the hardened layer 10 ′ is hardened by induction hardening on the surfaces of the seal land, the inner rolling surface 1 a, and the shoulder 16 of the outer joint member 14, which are in sliding contact with the seal lip of the seal 12. (Shown by dotted patterns in the figure). Here, the double-row rolling bearing 2 is exemplified by a double-row angular contact ball bearing using the rolling elements 9 and 9 as balls, but is not limited thereto, and may be a double-row tapered roller bearing using tapered rollers for the rolling elements. .
[0028]
In this type of bearing device for a drive wheel, of the double row rolling bearings 2, a relatively large moment load is applied to the inboard side. In order to balance the left and right rolling fatigue life, in the present embodiment, the PCD (pitch circle diameter) of the double row rolling elements 9, 9 is made different between the outboard side and the inboard side, and relatively. The PCD on the inboard side to which a large moment load is applied is set to have a slightly larger diameter than the outboard side to increase the load capacity. Alternatively, the number and size of the inboard-side rolling elements 9 may be changed to increase the load capacity of the inboard-side bearing.
[0029]
The constant velocity universal joint 3 includes an outer joint member 14, an inner joint ring 15, a cage 17, and a torque transmitting ball 18. The outer joint member 14 has a cup-shaped mouth portion 19, a shoulder 16 serving as a bottom of the mouth portion 19, and a shaft portion 20 extending from the shoulder 16 in the axial direction. A curved track groove 19a extending in the axial direction is formed.
[0030]
The inner rolling surface 14a described above is formed on the outer periphery of the shoulder 16 of the outer joint member 14 formed in a hollow. The shaft portion 20 has a small-diameter step portion 20a into which the spigot portion 1b of the hub wheel 1 is press-fitted, and a fitting portion 20b into which the hub wheel 1 is fitted. With the spigot portion 1b of the hub wheel 1 pressed into the small-diameter step portion 20a butted by the shoulder portion 16, the fitting portion 20b is fitted inside the hub wheel 1 and a mandrel is inserted into and removed from the inner diameter of the fitting portion 20b. For example, the diameter of the fitting portion 20b is expanded by an appropriate means such as removal, and the fitting portion 20b is made to bite into the uneven portion 5 of the hub wheel 1. The fitting portion 20b is caulked to plastically couple the hub wheel 1 and the outer joint member 14. . As a result, since this coupling portion has both the torque transmitting means and the coupling means for connecting the hub wheel 1 and the outer joint member 14, it is not necessary to form a conventional torque transmitting means such as serration on the hub wheel 1 or the outer joint member 14. In addition, it is possible to realize a lightweight and compact device.
[0031]
In the outer joint member 14, a surface hardening process is performed from the seal land portion where the seal 13 slides on the track groove 19a formed on the inner periphery of the mouth portion 19, the inner rolling surface 14a, and the small diameter step portion 20a. Quenching by high-frequency induction heating is preferred as the curing treatment. The fitting portion 20b to be expanded in diameter is an unquenched portion having a forged material surface hardness of 24 HRC or less, and the hardness difference between the surface hardness 54 to 64 HRC of the uneven portion 5 of the hub wheel 1 is 30 HRC or more. It is preferable to set. Thereby, the fitting portion 20b can easily and deeply bite into the concave-convex portion 5, and the two can be firmly plastically connected without the top end of the concave-convex portion 5 being crushed. An end cap 19b is attached to the inner diameter of the hollow outer joint member 14 to prevent the lubricating grease sealed in the mouth portion 19 from leaking out and invading dust from the outside.
[0032]
As described above, the uneven portion 5 is formed on the inner peripheral surface of the hub wheel 1, and the range of this portion 5 extends from the pilot portion 1 c of the wheel to the outboard side with the wheel mounting flange 4 interposed therebetween. It is set to the vicinity of the action line of the moving body 9 (a line extending from a contact point between the rolling body 9 and the inner rolling surface 1a and the center of the rolling body 9). An annular recess 21 is formed on the outboard side of the uneven portion 5. That is, as shown in FIG. 3A, the annular recess 21 is formed at the end portion on the outboard side of the enlarged diameter range L. When the diameter of the fitting portion 20b of the shaft portion 20 is increased, the outer diameter portion of the fitting portion 20b cuts into the uneven portion 5, but a part of the uneven portion 5 is removed in this manner to form an annular shape. By forming the recess 21, the fitting portion 20 b in this portion is not restrained, and the diameter is enlarged more. Therefore, the pull-out strength in the axial direction increases.
[0033]
In the diameter expansion test performed by the present applicant, it was found that the central portion of the diameter expansion range L was deepest in the uneven portion 5. This can be inferred from the shape of the inner surface of the fitting portion 20b shown in FIG. Therefore, forming the annular recess 21 in the center portion is not preferable because it increases the pull-out resistance but decreases the torque transmission capacity of the joint portion. Therefore, since the annular recess 21 for increasing the pull-out resistance is the same at any part in the axial direction, in the present embodiment, the end of the diameter expansion range L that can minimize the decrease in the torque transmission capacity, Is formed in a range of 0.5 to 3.0 times the peak pitch t0 of the annular groove 6a from the outboard side of the diameter expansion range L. If the annular recess 21 is further formed on the outboard side, the shear strength on the hub wheel 1 side decreases, and the desired pull-out strength cannot be expected. Further, if the annular recess 21 is further shifted to the inboard side, the torque transmission capacity of the coupling portion is greatly reduced, which is not preferable.
[0034]
In FIG. 3A, the width dimension t1 of the annular recess 21 is formed in a range of 0.5 to 3.0 times the peak pitch t0 of the independent annular groove 6a. The bottom diameter d5 of the annular recess 21 is 1.01 to 1.20 times the bottom diameter d4 of the annular groove 6a or the bottom diameter d3 of the axial groove 6b shown in FIG. Range.
[0035]
Here, if the width dimension t1 of the annular recess 21 is set to 0.5 times or less of the mountain pitch t0 of the annular groove 6a, not only the processing becomes difficult, but also the protrusion in the bulged portion buried in the annular recess 21 becomes difficult. The cross-sectional area is small, and an increase in pullout strength cannot be expected. On the other hand, if it is set to be 3.0 times or more the peak pitch t0, the torque transmission capacity of the coupling portion is greatly reduced, and the diameter expansion range L has to be expanded. Increasing the diameter expansion range L is not preferable because it increases the weight of the apparatus.
[0036]
Also, the reason why the bottom diameter d5 of the annular recess 21 is set in the range of 1.01 to 1.20 times the groove bottom diameter d4 of the annular groove 6a or the groove bottom diameter d3 of the axial groove 6b is as follows. It depends on the material of the outer joint member 14. For example, since the guaranteed minimum value of the elongation of S53C is 15%, 1.20 times is appropriate. Therefore, even if it is set to 1.20 times or more, it does not contribute to the pull-out strength, but rather decreases the strength of the hub wheel 1, which is not preferable.
[0037]
Here, the diameter expansion amount of the fitting portion 20b will be described. As described above, the diameter of the fitting portion 20b is expanded by appropriate means such as insertion and removal of the mandrel into and from the inner diameter of the fitting portion 20b, so that the fitting portion 20b bites into the uneven portion 5 of the hub wheel 1. The diameter expansion amount, that is, the inner diameter of the concavo-convex portion 5 of the hub wheel 1, fitting in consideration of the torque transmission capacity of the portion, the strength surface such as pull-out resistance, the ductility of the material, the workability, the life of the processing jig, and the like. The inner diameter of the portion 20b and the outer diameter of a diameter increasing jig such as a mandrel are determined. In the present embodiment, as shown in FIG. 3, after the diameter is increased, the outer diameter d2 of the fitting portion 20b is 1.01 times larger than the groove bottom diameter d4 of the annular groove 6a or the groove bottom diameter d3 of the axial groove 6b. It is set so as to be in a range of up to 1.15 times. The shape of the annular recess 21 is not limited to a rectangle, but may be a triangular annular recess 21 'shown in FIG. 5A or a semicircular annular recess 21 "shown in FIG. 5B. There may be.
[0038]
In the present embodiment, the so-called fourth generation structure in which the inner rolling surface 1a of the double row rolling bearing 2 is formed directly on the outer peripheral surface of the hub wheel 1 and the outer peripheral surface of the outer joint member 14 has been described. The present invention is not limited to this, and any conventional first to third generation structure may be used as long as the structure has a plastic coupling portion between the hub wheel and the outer joint member on the outboard side of the device. That is, even if a bending moment load is applied to the device during vehicle turning and the shaft portion of the outer joint member including the plastic joint portion is bent and repeated stress is generated without damaging the features of the respective structures, The loosening can be prevented, the decrease in the torque transmission capacity of the plastic coupling portion can be suppressed, and the pullout strength can be increased with a simple configuration.
[0039]
FIG. 6A is a sectional view of a main part of a second embodiment of the drive wheel bearing device according to the present invention, and FIG. 6B is a side view thereof. Here, the concave and convex portions 5 are formed on the inner peripheral surface of the hub wheel 1 ', and the annular recess 21 is formed on the outboard side. The only difference from the first embodiment described above is that, in addition to the annular recess 21 shown in FIG. 3, the annular recess 21 is also formed at the inboard end of the enlarged diameter range L. The same parts and the same parts are denoted by the same reference numerals and the description thereof will be omitted. As described above, by forming the annular recesses 21 at both ends of the enlarged diameter range L, it is possible to suppress a decrease in the torque transmission capacity of the coupling portion and further increase the pull-out resistance. The specifications such as the position and size of the annular recess 21 are the same as those in the first embodiment.
[0040]
FIG. 7A is a sectional view of a main part showing a third embodiment of a drive wheel bearing device according to the present invention, and FIG. 7B is a side view thereof. The only difference from the above-described embodiment is the configuration of the hub wheel. The same reference numerals are assigned to the same parts and other parts, and detailed description thereof will be omitted.
[0041]
The hardened uneven portion 5 is formed on the inner peripheral surface of the hub wheel 22, and the fitting portion 20 b of the shaft portion 20 of the outer joint member 14 is cut into the uneven portion 5, thereby forming the hub wheel 22 and the outer joint member. 14 are plastically connected. The range of the uneven portion 5 extends from the wheel pilot portion 22a to the vicinity of the line of action of the rolling element (not shown) on the outboard side with the wheel mounting flange 4 interposed therebetween, as in the above-described embodiment. Here, the end face on the outboard side of the hub wheel 22 is spotted to form an annular recess 23. Here, by expanding the diameter of the fitting portion 20b of the shaft portion 20, the outer diameter portion of the fitting portion 20b cuts into the uneven portion 5, but a part of the uneven portion 5 is removed in this way. By forming the annular recess 23 in this manner, the fitting portion 20b in this portion is not constrained, and the diameter is enlarged more. Therefore, the swelling portion in the annular recess 23 increases the withdrawal strength in the axial direction.
[0042]
In FIG. 7A, the depth of the annular recess 23, that is, the dimension t2 from the end face 20c of the fitting portion 20b is 0.5 to 3.0 times the mountain pitch t0 of the independent annular groove 6a. Formed in the range. The bottom diameter d5 of the annular recess 23 is equal to or larger than the bottom diameter d4 of the annular groove 6a or the bottom diameter d3 of the axial groove 6b shown in FIG. 7B, and the outer diameter of the pilot portion 22a in the hub wheel 22. It is formed with a diameter 1 mm smaller than D1, that is, D1-1.
[0043]
Here, when the depth t2 of the annular recess 23 is set to 0.5 times or less of the mountain pitch t0 of the annular groove 6a, the area of the shear surface of the portion bulging into the annular recess 23 becomes small, No increase in pullout strength can be expected. On the other hand, if it is set to be 3.0 times or more of the peak pitch t0, the torque transmission capacity of the coupling portion is greatly reduced, which is not preferable.
[0044]
The reason why the bottom diameter d5 of the annular recess 23 is set to be equal to or less than D1-1 is from the viewpoint of the strength and workability of the pilot portion 22a. Therefore, the present invention is not limited to this, and similarly to the annular recess 21 of the above-described embodiment, a range of 1.01 to 1.20 times the groove bottom diameter d4 of the annular groove 6a or the groove bottom diameter d3 of the axial groove 6b. May be set.
[0045]
Further, as in the above-described embodiment, the diameter expansion amount of the fitting portion 20b is determined in consideration of the strength of the coupling portion such as torque transmission capacity and pull-out strength, the ductility of the material, the workability, and the life of the processing jig. , The inner diameter of the uneven portion 5 of the hub wheel 1, the inner diameter of the fitting portion 20b, and the outer diameter of the expanding jig such as the mandrel. That is, after the diameter is increased, the outer diameter d2 of the fitting portion 20b is in a range of 1.01 to 1.15 times the groove bottom diameter d4 of the annular groove 6a or the groove bottom diameter d3 of the axial groove 6b. Is set to
[0046]
As described above, the embodiments of the present invention have been described. However, the present invention is not limited to these embodiments at all, but is merely an example, and may be variously modified without departing from the gist of the present invention. The scope of the present invention is, of course, indicated by the appended claims, and further includes the equivalent meanings described in the appended claims and all modifications within the scope. Including.
[0047]
【The invention's effect】
As described in detail above, the drive wheel bearing device according to the present invention is a unitized hub wheel, constant velocity universal joint, and double-row rolling bearing, and the hub wheel and the outer joint member of the constant velocity universal joint. The hub wheel has at least one inner rolling surface of the inner rolling surfaces in the double row rolling bearing, and a fitting portion between the hub wheel and the outer joint member has an outer diameter side. In addition to forming a hardened uneven portion on the member arranged in the above, the member arranged on the inner diameter side is enlarged and bite into this uneven portion, and the hub wheel and the outer joint member are integrated by plastic coupling. In the bearing device for a drive wheel described above, the concave and convex portions are partially removed to form a predetermined annular recess, and a part of the member disposed on the inner diameter side is swelled in the annular recess. The fitting portion of the portion is enlarged by a larger diameter without being restrained by the uneven portion. Therefore, the pull-out strength of the hub wheel and the outer joint member increases with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of a drive wheel bearing device according to the present invention.
FIG. 2 (a) is a longitudinal sectional view showing the shape of a concave and convex portion of a hub wheel according to the present invention.
The figure shows an iris knurled shape composed of spiral grooves.
(B) Same as above, an iris lorele composed of an intersection groove of an axial groove and an independent annular groove.
This shows the cut shape.
FIG. 3 (a) is a view showing a first embodiment of a drive wheel bearing device according to the present invention.
It is a fragmentary sectional view.
(B) is a top view of the same.
FIG. 4 is an explanatory view of a plastic coupling portion in the drive wheel bearing device according to the present invention.
FIG. 5 (a) is an enlarged view of a main part showing another embodiment of the annular recess according to the present invention.
(B) is a principal part enlarged view which shows another embodiment same as the above.
FIG. 6 (a) is a cross-sectional view of a main part showing a second embodiment of a bearing device for a drive wheel according to the present invention.
FIG.
(B) is a top view of the same.
FIG. 7 (a) is a cross-sectional view of a principal part showing a third embodiment of the drive wheel bearing device according to the present invention.
FIG.
(B) is a top view of the same.
FIG. 8 is a longitudinal sectional view showing a conventional drive wheel bearing device.
FIG. 9
[Explanation of symbols]
1, 1 ', 22 ... hub wheel
1a, 14a ... inner rolling surface
1b ······ Inlay part
1c, 22a ... pilot section
2 Double-row rolling bearing
3 ... Constant velocity universal joint
4 Wheel flange
5...
6, 6 '... groove
6a ..... annular groove
6b ······· Axial groove
7 outer member
7a ..... body mounting flange
7b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer rolling surface
8 Inner member
9 Rolling element
10, 10 '... cured layer
11 ······ Cage
12, 13, .... Seal
14 ... Outer joint member
15 ・ ・ ・ ・ ・ ・ ・ ・ Inner ring of joint
16 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shoulder
17 ... Cage
18 ... Torque transmission ball
19 ······ Mouse part
19a ······ Track groove
19b ... End cap
20 ······ Shaft
20a ... small diameter step
20b ..... fitting part
20c ······ End face of fitting portion
21, 23 ... Annular recess
21 ', 21 "... annular recess
50, 50 '... hub wheel
50a, 71a ... inner rolling surface
51 · · · · · · Wheel mounting flange
52 hub bolt
53 ...
········ Double row rolling bearing
61 ・ ・ ・ ・ ・ ・ ・ Outer member
61a ... outer rolling surface
62 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inner member
63 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rolling element
64 ····· Car body mounting flange
65 ・ ・ ・ ・ ・ ・ ・ ・ Cage
66, 67 ... Seal
70, 70 '... Constant velocity universal joint
71, 71 '... outer joint member
72 ······ Mouse section
72a ······· Track groove
73 ・ ・ ・ ・ ・ ・ ・ ・ Shaft
74 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Caulking part
d2 ..... outer diameter of fitting part
d3 ········ A groove bottom diameter of the axial groove
d4 · · · · · · · Groove bottom diameter of annular groove
d5 ·········· Bottom diameter of annular recess
D1 ..... outer diameter of pilot section
L ... Diameter expansion range
t0 ... Pitch of annular groove
t1 ·········· Width of annular recess
t2: Depth of annular recess
