JP3977975B2

JP3977975B2 - Constant velocity universal joint

Info

Publication number: JP3977975B2
Application number: JP2000015959A
Authority: JP
Inventors: 真一 ▼高▲部
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2000-01-25
Filing date: 2000-01-25
Publication date: 2007-09-19
Anticipated expiration: 2020-01-25
Also published as: JP2001208215A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車の駆動系等に使用される等速自在継手に関するもので、特にブーツを取付けるためのブーツ取付け部を有する等速自在継手に関する。
【０００２】
【従来の技術】
等速自在継手には、継手内部に封入されたグリースの漏れ出し防止や継手内部への異物侵入防止を目的として、ブーツが装着される。ブーツは、等速自在継手を構成する外側継手部材のブーツ取付け部、および軸部のブーツ取付け部にそれぞれブーツバンドで締付け固定される。この等速自在継手用ブーツとしては、クロロプレンゴム（CR）等のゴム材料からなるゴムブーツと、樹脂材料からなる樹脂ブーツが一般的であるが、近時では、耐回転膨張性や耐久性等の面から樹脂ブーツが多く使用される傾向にある。
【０００３】
特に樹脂ブーツは、ゴムブーツに比べて弾性が小さいために、相手部材への嵌め込み状態が不安定になり易いこともあって、相手部材との取付け構造に特別な工夫が必要とされる。
【０００４】
図９は、従来の樹脂ブーツの取付け構造例で、樹脂ブーツ１の大径端側と小径端側の端部にそれぞれ設けられた円筒状の固定部２を、相手部材６（等速自在継手の外側継手部材や軸部）の外周に設けられたブーツ取付け部４に嵌合した後、固定部２の外周をブーツバンド３で締付けて弾性変形させ、その内周に設けた環状の凸部２ａを、ブーツ取付け部４に設けた環状溝状の係合溝４ａに係合密着させて樹脂ブーツ１を固定するものである。
【０００５】
図１０（Ａ）（Ｂ）は、例えば特開平7-280092号公報などに開示された他のブーツ取付け構造例である。この取付け構造では、ブーツ一端部の固定部２の内周に環状の凸部２ａが一体形成され、外周に環状のバンド溝５が形成される。相手部材６のブーツ取付け部４の外周には環状の係合溝４ａと、この係合溝４ａの両側に環状の突起部７とが一体に形成される。係合溝４ａは、例えば曲率半径R'の円弧溝で、その両側の溝肩部が突起部７になっている。係合溝４ａの幅ｂと深さａは、ここに固定部２の凸部２ａが適正に嵌合するように設定され、突起部７はブーツ取付け部４の外周から所定の高さｃで突出する。
【０００６】
固定部２を相手部材６のブーツ取付け部４外周に嵌挿し、凸部２ａを係合溝４ａに嵌合させて両者を位置決めした状態で、バンド溝５に嵌着したブーツバンド３を縮径させ、固定部２を相手部材６に締付けると、固定部２の内周側が弾性変形を起こして凸部２ａが係合溝４ａ側に変位し、突起部７が固定部２の内周側に食い込む。この凸部２ａおよび係合溝４ａの嵌合と突起部７の強い食い込みとで、固定部２が相手部材６に高い抜け止め強度とシール性で固定される。なお、図１０（Ａ）はブーツバンド３の締付け前の状態を表わしている。
【０００７】
【発明が解決しようとする課題】
図９の構造では、ブーツ固定部２の抜け止め強度とシール性を確保するために、ブーツ固定部２の凸部２ａの高さｈを比較的大きくする必要があるため、樹脂ブーツの成形方法が限定され、このことがコスト高の要因となっている。また、樹脂ブーツは一般にゴムブーツに比べて硬度がかなり高く、弾性変形し難いので、凸部２ａが高いと相手部材６への嵌合作業が困難になり、一方、この嵌合作業を少しでも容易にするために凸部２ａを低くすると、シール性の悪化を招く。
【０００８】
これに対し、図１０の構造では、上記作業性やシール性については、かなりの改善が図られているが、ブーツ取付け部４の外周形状が図９に比べて複雑化しているため、旋削代が多い、加工工程が煩雑化する等の理由からコスト高となる場合がある。また、突起部７が存在するためにブーツ取付け後の外径寸法が大きくなって車両への取付けスぺースが制限される等の不具合を招くおそれもある。
【０００９】
そこで、本発明では、ブーツの取付け部での確実なシール性および抜け止め性を確保しつつ、ブーツ取付け時の作業性向上を図り、併せて製造コストの低減を図ることのできる等速自在継手の提供を目的とする。
【００１０】
【課題を解決するための手段】
上記目的を達成するため、本発明では、ブーツの一端に設けられた固定部を取付けるためのブーツ取付け部と、ブーツ取付け部に設けられ、上記ブーツの固定部内周に設けられた凸部と係合可能な係合溝とを備え、ブーツの固定部外周に嵌合したブーツバンドの締付け力によって上記ブーツ取付け部とブーツの固定部とを密着させる等速自在継手において、係合溝を、ブーツ他端側が縮径する第二テーパ面と、第二テーパ面の小径側に連続する円弧面とで形成し、第二テーパ面と円弧面の大径側をそれぞれブーツ取り付け部の外周面につなげ、ブーツ取付け部のうち、係合溝のブーツ他端側の溝肩部に、溝肩部外周面と係合溝のブーツ他端側の壁面の外径端部とがなす角度が鋭角の鋭角部を設け、ブーツ取付け部のうち、係合溝よりもブーツ一端側の外周面全体を円筒面状の平滑面とし、ブーツバンドの締付け力によって、平滑部にブーツの固定部の円筒状内周面を密着させた。鋭角部は、ブーツの抜け方向に抵抗する形で（ブーツの抜け方向と反対側から）固定部内周に食い込むので、ブーツ取付け部において十分な抜け止め性とシール性とが確保される。
【００１１】
なお、ここでいうブーツの「一端」は、ブーツの大径端もしくは小径端の何れでもよく、同様に「他端」もブーツの小径端もしくは大径端の何れでもよい。
【００１２】
上記ブーツ取付け部は、例えば外側継手部材の外周に形成することができる。
【００１３】
ブーツ取付け部のうち、係合溝よりもブーツ一端側の外周面を、従来のような突起部７（図１０参照）のない平滑面とすることにより、ブーツ取付け部の外周形状が簡略化されるので、ブーツ取付け部を加工する際の削り代の減少や加工工程の簡略化による製造コストの低減が可能となる。この場合でも鋭角部の強力な食い込み作用により、抜け止め性やシール性は必要十分に確保される。
【００１４】
鋭角部は、例えば溝肩部の外周面をブーツ他端側が縮径する第一テーパ面とすることにより形成され得る。
【００１５】
第一テーパ面の傾斜角は、これが大きすぎると固定部との密着度が低下してシール性の低下を来すおそれがあるので、１〜５°の範囲、より望ましくは２°に設定するのがよい。
【００１６】
第一テーパ面のブーツ他端側に円筒面を形成することにより、第一テーパ面のみの場合に比べて、ブーツバンドの締付け時に当該円筒面に密着する固定部内周の変形量が少なくなるので、両者の密着度が高まり、シール性を向上させることができる。
【００１７】
この他、ブーツの一端に設けられた固定部を取付けるためのブーツ取付け部と、ブーツ取付け部に設けられ、上記ブーツの固定部内周に設けられた凸部と係合可能な係合溝とを備え、ブーツの固定部外周に嵌合したブーツバンドの締付け力によって上記ブーツ取付け部とブーツの固定部とを密着させる等速自在継手において、係合溝を、ブーツ他端側が縮径する第二テーパ面と、第二テーパ面の小径側に連続する円弧面とで形成し、第二テーパ面と円弧面の大径側をそれぞれブーツ取り付け部の外周面につなげ、ブーツ取付け部のうち、係合溝のブーツ他端側の溝肩部に外周が円筒面の突起部を設けると共に、係合溝よりもブーツ一端側の外周面全体を円筒面状の平滑面とし、ブーツバンドの締付け力によって、平滑部にブーツの固定部の円筒状内周面を密着させても同様の効果が得られる。
【００１９】
係合溝を、ブーツ他端側が縮径する第二テーパ面と、これに連続する円弧面とで形成することにより、係合溝を倣い加工することが可能となるので、加工コストのさらなる低減が図られる。
【００２０】
上記第二テーパ面の傾斜角は２５〜３０°にするのが望ましい。この傾斜角は係合溝を加工する際の加工工具（旋削チップ等）の傾きに対応したものである。
【００２１】
係合溝の溝深さを凸部の高さよりも大きくし、溝底と凸部との間に隙間を設けることにより、ブーツバンドの締付け時に凸部が係合溝の底に接触して弾性変形し、その変形分の反力だけ鋭角部の食い込み性が低下する事態を防止することができる。
【００２２】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
【００２３】
図１は、蛇腹状のブーツ２０を、ブーツバンド３０を使用して取付けた等速自在継手１０を示している。等速自在継手１０は、内周面に複数の案内溝１１を軸方向に形成した外側継手部材１２と、外周面に複数の案内溝１３を軸方向に形成した内側継手部材１４と、案内溝１１と案内溝１３とが協働して形成されるボールトラックに配された複数のボール１５と、ボール１５を保持する保持器１６と、内側継手部材１４の内周にセレーション連結（又はスプライン連結）された軸部１７とを備えている。
【００２４】
ブーツ２０は、ＣＲ等のゴム材料や樹脂材料などの可撓性材料で形成される。たとえば樹脂ブーツの場合、樹脂材料としては、３８≦Ｈ_D≦５０、好ましくは３８≦Ｈ_D≦４７、たとえばＨ_D＝４７の硬度を有する熱可塑性ポリエステル系エラストマー（ＴＰＥＥ）が使用される。ここでいう「Ｈ_D」は、ショアー硬さのＤスケール（ＡＳＴＭに準拠）を表わしている。
【００２５】
このブーツ２０は、外側継手部材１２と軸部１７の各外周にそれぞれブーツバンド３０を使用して固定される。このブーツ２０は、蛇腹部２１と、蛇腹部２１の両側に設けられた円筒状の固定部２２，２３とを具備し、ブーツ２０の一端側、例えば大径端側に設けられた固定部２２が外側継手部材１２のブーツ取付け部４０ａに、他端側（小径端側）に設けられた固定部２３が軸部１７のブーツ取付け部４０ｂにそれぞれ固定される。
【００２６】
図２および図３は、外側継手部材１２のブーツ取付け部４０ａ、およびブーツ一端側の固定部２２を拡大して示している。このうち、図２はブーツバンド３０による締付け前の状態を、図３は締付け後の状態を示している。
【００２７】
外側継手部材１２のブーツ取付け部４０ａは、通常、外側継手部材１２の開口側の端部外周面に設けられる。図示例のブーツ取付け部４０ａは、外側継手部材１２の端部外周面を部分的に縮径させた小径円筒面状に形成され、その軸方向のほぼ中心部に環状の係合溝４１を具備している。係合溝４１のブーツ他端側（図面右側）の溝肩部（係合溝４１の外周縁部）には鋭角部４２が形成される。鋭角部４２は、溝肩部外周面４３と係合溝４１のブーツ他端側の壁面４１ａ（特にその外径端部）とがなす角度を鋭角にしたもので、本実施形態では、上記ブーツ他端側壁面４１ａを、その外径端を通る接線を軸線X−X（図1参照）と直交方向に向けた円弧面とする一方で、溝肩部外周面４３をブーツ他端側が縮径するテーパ面（第一テーパ面）とした場合を例示している。第一テーパ面４３の軸線Ｘ−Ｘに対する傾斜角θ₁は、これが大きすぎると固定部２２との密着度の低下を招くので、１°以上５°以下程度とし、望ましくは２°狙いとする（図面ではこの傾斜角θ₁を誇張して描いている）。鋭角部４２の最大外径寸法は、係合溝４１のブーツ一端側に形成された円筒状の平滑面４４の外径寸法と等しい。
【００２８】
係合溝４１は、ブーツ取付け部４０ａ外周の所定箇所を例えば旋削することによって形成される。図示例の係合溝４１形状は、旋削チップ形状に対応した形状となっている。具体的にはブーツ他端側の壁面４１ａは旋削チップのノーズのアール形状に対応した円弧面、ブーツ一端側の壁面４１ｂは旋削チップの傾きに対応した、ブーツ他端側を小径とするテーパ面（第二テーパ面）になっており、両面４１ａ，４１ｂは滑らかに連続している。傾向溝４１をこのような形状とすることにより、係合溝４１の倣い加工が可能となるので、加工性の向上と製造コストの低減を図ることができる。
【００２９】
ブーツ他端側の壁面４１ａのR寸法は、これが小さすぎると係合溝４１の倣い加工が困難となって加工性の低下や製造コストの高騰を招き、大きすぎるとシール性や抜け止め性の低下を招くので、R＝０．８〜１．２mm（望ましくは１．２mm）の範囲内に設定するのがよい。また、第二テーパ面４１ｂの軸線方向に対する傾斜角θ₂は、旋削チップとして広く使用される三角チップや菱形チップに対応して、例えば25〜30°に設定される。
【００３０】
ブーツ一端側の固定部２２は、上記係合溝４１に嵌合する環状の凸部２４を内周面に具備する。図示例では凸部２４として、係合溝４１形状に対応して円弧部２４ａとテーパ部２４ｂとを具備するものを例示しているが、凸部２４の形状は、係合溝４１に嵌合可能である限り任意に変更可能である。
【００３１】
この凸部２４は、係合溝４１にスムーズに嵌合できるよう、その軸方向長さは係合溝４１の軸方向長さLよりも僅かに小さくなっている。係合溝４１の溝深さHが小さすぎると、締付け時に凸部２４が係合溝４１の底に接触して弾性変形し、その変形分の反力だけ鋭角部４２の食い込み性が低下する。そのため、これに応じて凸部２４の高さｈを小さくせざるを得なくなり、凸部２４による係合溝４１への位置固定の効果が低下する。従って、係合溝４１の溝深さHと凸部２４の高さｈの関係は、締付け時に凸部２４が係合溝４１の底に接触しないか、接触しても鋭角部４２の食い込み性に影響を与えないように設定される。これに対応すべく、本実施形態では、溝深さＨを凸部２４の高さｈよりも大きく設定している（Ｈ＞ｈ）。
【００３２】
ブーツ一端側の固定部２２を外側継手部材１２のブーツ取付け部４０ａに嵌挿し、凸部２４を係合溝４１に嵌合させて両者を位置決めした状態で、固定部２２外周のバンド溝２５に嵌着したブーツバンド３０を縮径させて固定部２２をブーツ取付け部４０ａに締付けると、図３に示すように、固定部２２の内周側が弾性変形を起こして凸部２４が係合溝４１側に変位し、鋭角部４２が凸部２４の立ち上り部分２４ｃに食い込む。この凸部２４と係合溝４１との嵌合、および鋭角部４２の固定部２２内周への食い込みで固定部２２がブーツ取付け部４０ａに高い抜け止めとシール性をもって固定される。また、固定部２２の内周面がブーツ取付け部４０ａの外周面（第一テーパ面４３および平滑面４４）に適度に密着するため、良好なシール性が得られる。
【００３３】
特に本発明では、係合溝４１の溝肩部が鋭角に形成されているので、鋭角部４２の固定部２２への食い込みが強固かつスムーズになされ、これより高い抜け止め効果とシール性、および良好な作業性が確保される。
【００３４】
その一方で、ブーツ取付け部４０ａのうち、係合溝４１よりもブーツ大端側の外周領域はその全体が平滑面４４であり、しかも本実施形態においては係合溝４１よりもブーツ他端側の外周領域が第一テーパ面４３のみで形成されているため、ブーツ取付け部４０に２つの突起部７を有する従来品（図１０参照）に比べてブーツ取付け部４０ａの外周形状を簡略化することができる。従って、旋削代の削減や加工工程の簡略化による製造コストの低減が達成される。また、突起部がない分だけブーツ取付け部４０ａの外径寸法、さらにはブーツ２０の外径寸法を小さくすることができ、等速自在継手１０の小型化や軽量化、材料コストや加工コストの低減を図ることができる。
【００３５】
以上の実施形態では、外側継手部材１２のブーツ取付け部４０ａに固定部２２を取付ける場合を説明したが、図２および図３の示す構造は、軸部１７のブーツ取付け部４０ｂにブーツ他端側（小径端側）の固定部２３を取付ける場合にも同様に適用することができる。この場合、係合溝のブーツ一端側（大径端側）の溝肩部に上記鋭角部４２が形成され、係合溝よりもブーツ他端側に上記平滑面４４が形成される。また、ブーツの一端側と他端側の双方の取付けに本発明を適用する他、何れか一端側の取付けに本発明を、他端側の取付けに従来構造を適用してもよい。図１は、その一例で、ブーツ一端側の取付けに図２および図３に示す構造を、ブーツ他端側の取付けに図１０に示す従来構造を適用したものである。
【００３６】
図４は、本発明の第二の実施形態で、第一テーパ面４３のブーツ他端側に軸線と平行な円筒面４５を形成したものである。この場合、円筒面４５に密着する固定部２２内周面の変形量が図２および図３の場合に比べて小さくなるので、両者の密着度を高めてシール性の向上を図ることができる。これ以外の点は上記と同様であるので、図２および図３と共通する部材に共通の参照番号を付して重複説明を省略する。
【００３７】
図５は、本発明の第三の実施形態で、係合溝４１のブーツ他端側の溝肩部に、鋭角部４２に代えて突起部４６を形成したものである。この場合も図２〜図４と同様に、係合溝４１よりもブーツ一端側の外周に円筒面状の平滑面４４が形成される。突起部４６は、係合溝４１の溝肩部に形成された円筒面４６ａと、そのブーツ他端側に隣接して、ブーツ他端側を縮径させたテーパ面４６ｂとからなる。円筒面４６ａは平滑面４４と同径であり、ブーツバンド３０による締付け後には、この突起部４６が固定部２２に食い込む。これ以外の点は図２および図３に示す構成と同様であるので、共通する部材に同一参照番号を付して重複説明を省略する。
【００３８】
図６は、特に樹脂ブーツを使用する場合に好適なブーツバンド３０を示している。ブーツバンド３０は、帯状の金属材からなるバンド部材３１を輪状に湾曲させてその両端を掌合状態に結合すると共に、この掌合部３２の一方の外側面に、バンド部材３１よりも厚肉で剛性の高い金属材からなるレバー部材３３を固着したものである。バンド部材３１およびレバー部材３３は、たとえばステンレス鋼で形成される。
【００３９】
レバー部材３３にはバレル加工が施され、加工時のバリやエッジが除去されると共に、表面硬度の向上が図られている。バレル加工に代えてショットブラスト処理又はショットピーニング処理を施しても良い。さらに、バンド部材３１の内側面には、突出部３４が設けられている。この突出部３４は、たとえばバンド部材３１の所要部位を内側に屈曲させて成形したものである。突出部３４をバンド部材３１とは別に製作し、バンド部材３１の内側面の所要部位に固着しても良い。
【００４０】
固定部２２，２３を締付けるに際しては、レバー部材３３を、てこ作用を利用して強制的に折り返した後、図7（Ａ）に示すように、レバー部材３３をバンド部材３１の外側面に重ね合わせて止め具３５で固定する。レバー部材３３を折り返すことにより、バンド部材３１の輪状部分が縮径して、固定部２２，２３に所要の緊迫力（締付け力）が与えられる。止め具３５は、たとえば図7（Ｂ）（Ｃ）に示すように、コ字形断面の金属片をバンド部材３１の所定部位に固着したものである。レバー部材３３を固定するに際しては、その両側を折曲させ、レバー部材３３の外側面に重ね合わせる。なお、止め具はこれに限定されず、他の構造のものを採用することができる。また、レバー部材３３の固定手段として、止め具３５に代えて、スポット溶接等の固着手段を採用することもできる。
【００４１】
図8に示すように、レバー部材３３を折り返した時、バンド部材３１の一部がレバー部材３３の折り返し起点によって折返され、掌合部３２がレバー部材３３の外側面に重なり合った状態になる。そのため、バンド部材３１の折り返し部分３１ａと近接する部分（レバー部材３３の折り返し方向と反対側）に部分的な隙間が生じ、その部分でシール性の低下が起こり易い。そこで、この実施形態では、バンド部材３１の内側面に突出部３4を設け、この突出部３4を固定部２２の外側面（バンド溝２５）に接触させて、上記隙間を詰めることにより、シール性の向上を図っている。この突出部３4は、少なくとも一個所以上、好ましくは、レバー部材３３を折り返した時に、バンド部材３１の折り返し部分３１ａと近接する位置に設ける。また、突出部３４の形状、寸法、形成位置を最適設計し、突出部３４の端面とバンド部材３１の折返し部分３１ａとの間の円周方向隙間γの最大値が０＜γ≦１．５ｍｍとなるように設定することにより、シール性の向上に対してより好ましい状態となる。
【００４２】
ブーツバンド３０としては、上述のものに限らずに種々のブーツバンド、例えばオメガ（Ω）形状のクランプ部を有し、このクランプ部を加締めることによって締付け力を得るタイプのバンド（オメガバンド）や、帯材の一端に引掛けフックを、他端にフックを引掛ける穴部を有する引掛けバンド等が広く使用可能である。
【００４３】
【発明の効果】
本発明によれば、係合溝の溝肩部に鋭角部を設けることによって固定部への食い込み力を強化しているので、ブーツの取付け部でのシール性および抜け止め性を向上させることができる。また、この鋭角部は固定部に円滑に食い込むことができるので、ブーツ取付け時の作業性向上を図ることができる。鋭角部は例えば溝肩部の外周面にテーパ面を形成する等の手段で簡単に形成することができるので、製造コストも安価に抑えることができる。
【図面の簡単な説明】
【図１】ブーツを等速自在継手に取付けた時の状態を示す縦断面図である。
【図２】外側継手部材のブーツ取付け部およびブーツ一端側の固定部を示す拡大断面図である（ブーツバンドの締付け前）。
【図３】外側継手部材のブーツ取付け部およびブーツ一端側の固定部を示す拡大断面図である（ブーツバンドの締付け後）。
【図４】本発明の第二の実施形態を示す縦断面図である。
【図５】本発明の第三の実施形態を示す縦断面図である。
【図６】ブーツバンドの側面図である。
【図７】ブーツバンドのレバー部材を折り返した時の状態を示す側面図（図Ａ）、止め具を例示する断面図（図ＢおよびＣ）である。
【図８】ブーツの固定部をブーツバンドで締付けてブーツ取付け部に固定した時の状態を示す断面図である。
【図９】従来の等速自在継手を示す縦断面図である。
【図１０】従来の等速自在継手を示す縦断面図である。
【符号の説明】
１０等速自在継手
１２外側継手部材
２０ブーツ
２１蛇腹部
２２固定部
２３固定部
２４凸部
３０ブーツバンド
４０ａ外側継手部材のブーツ取付け部
４０ｂ軸部のブーツ取付け部
４１係合溝
４２鋭角部
４３第一テーパ面
４４平滑面
４５円筒面
４６突起部
４６ａ円筒面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a constant velocity universal joint used for a drive system of an automobile, and more particularly to a constant velocity universal joint having a boot attachment portion for attaching a boot.
[0002]
[Prior art]
A boot is attached to the constant velocity universal joint for the purpose of preventing leakage of grease enclosed in the joint and preventing foreign matter from entering the joint. The boots are fastened and fixed to the boot attachment portion of the outer joint member constituting the constant velocity universal joint and the boot attachment portion of the shaft portion with a boot band, respectively. As the boots for constant velocity universal joints, rubber boots made of a rubber material such as chloroprene rubber (CR) and resin boots made of a resin material are generally used. Recently, however, such as rotational expansion resistance and durability, etc. From the surface, resin boots tend to be used frequently.
[0003]
In particular, since the resin boot is less elastic than the rubber boot, the fitting state with the mating member tends to become unstable, and a special device is required for the mounting structure with the mating member.
[0004]
FIG. 9 shows an example of a conventional resin boot mounting structure. A cylindrical fixing portion 2 provided at each of the large-diameter end side and the small-diameter end side of the resin boot 1 is replaced with a mating member 6 (constant velocity universal joint). Of the outer joint member and the shaft portion of the outer peripheral member of the outer peripheral portion of the outer periphery of the fixing portion 2, and the outer periphery of the fixing portion 2 is elastically deformed by tightening the outer periphery of the fixing portion 2 with the boot band 3. 2a is engaged and brought into close contact with an annular groove-like engagement groove 4a provided in the boot mounting portion 4, and the resin boot 1 is fixed.
[0005]
FIGS. 10A and 10B are other examples of boot mounting structures disclosed in, for example, Japanese Patent Laid-Open No. 7-280092. In this mounting structure, an annular convex portion 2a is integrally formed on the inner periphery of the fixed portion 2 at one end of the boot, and an annular band groove 5 is formed on the outer periphery. An annular engagement groove 4a and annular projections 7 are formed integrally on the outer periphery of the boot mounting portion 4 of the mating member 6 and on both sides of the engagement groove 4a. The engagement groove 4 a is, for example, an arc groove having a curvature radius R ′, and the groove shoulders on both sides thereof are the protrusions 7. The width b and the depth a of the engaging groove 4a are set so that the convex part 2a of the fixing part 2 fits properly here, and the protrusion part 7 has a predetermined height c from the outer periphery of the boot mounting part 4. Protruding.
[0006]
The diameter of the boot band 3 fitted in the band groove 5 is reduced in a state in which the fixing portion 2 is fitted on the outer periphery of the boot mounting portion 4 of the mating member 6 and the convex portion 2a is fitted in the engagement groove 4a and both are positioned. When the fixing portion 2 is fastened to the mating member 6, the inner peripheral side of the fixing portion 2 is elastically deformed, the convex portion 2 a is displaced toward the engaging groove 4 a side, and the protruding portion 7 is moved to the inner peripheral side of the fixing portion 2. Bite. The fixing portion 2 is fixed to the mating member 6 with a high retaining strength and a sealing property by the fitting of the convex portion 2 a and the engaging groove 4 a and the strong biting of the protruding portion 7. 10A shows a state before the boot band 3 is tightened.
[0007]
[Problems to be solved by the invention]
In the structure of FIG. 9, the height h of the convex portion 2 a of the boot fixing portion 2 needs to be relatively large in order to ensure the retaining strength and sealing performance of the boot fixing portion 2. However, this is a factor of high cost. In addition, resin boots are generally much harder than rubber boots and are less likely to be elastically deformed. Therefore, if the convex portion 2a is high, it is difficult to fit the mating member 6, while this fitting work is a little easier. If the convex portion 2a is lowered in order to reduce the sealing performance, the sealing performance is deteriorated.
[0008]
On the other hand, in the structure of FIG. 10, the above workability and sealability are considerably improved, but the outer peripheral shape of the boot mounting portion 4 is more complicated than that of FIG. In many cases, the cost is increased due to reasons such as complicated processing steps. In addition, since the protrusion 7 is present, the outer diameter after the boot is attached is increased, which may cause a problem such as a restriction of the attachment space to the vehicle.
[0009]
Therefore, in the present invention, a constant velocity universal joint capable of improving workability at the time of mounting the boot while reducing the manufacturing cost while ensuring a reliable sealing property and a retaining property at the mounting portion of the boot. The purpose is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a boot attachment portion for attaching a fixing portion provided at one end of the boot, and a protrusion provided on the inner periphery of the fixing portion of the boot, provided at the boot attachment portion. In the constant velocity universal joint, the engagement groove is formed on the boot by a fastening force of a boot band fitted to the outer periphery of the fixed portion of the boot. The other end side is formed with a second tapered surface with a reduced diameter and a circular arc surface continuous with the small diameter side of the second tapered surface, and the second tapered surface and the large diameter side of the circular arc surface are respectively connected to the outer peripheral surface of the boot mounting portion. In the boot mounting portion, the acute angle of the groove shoulder portion on the other end side of the engagement groove between the outer peripheral surface of the groove shoulder portion and the outer diameter end portion of the wall surface on the other end side of the engagement groove is an acute angle. the part is provided, out of the boot mounting portion, boots than the engaging groove The entire outer peripheral surface of the end side cylindrical surface shape of the smooth surface, the clamping force of the boot band, was brought into close contact with the cylindrical inner peripheral surface of the fixed portion of the boot to the smooth portion. Since the acute angle portion bites into the inner periphery of the fixed portion in a form that resists the boot removal direction (from the opposite side of the boot removal direction), a sufficient retaining property and sealing performance are secured at the boot mounting portion.
[0011]
The “one end” of the boot here may be either the large-diameter end or the small-diameter end of the boot. Similarly, the “other end” may be either the small-diameter end or the large-diameter end of the boot.
[0012]
The boot attachment portion can be formed on the outer periphery of the outer joint member, for example.
[0013]
Of the boot mounting portion, the outer peripheral surface on one end side of the boot with respect to the engagement groove is a smooth surface without the projection 7 (see FIG. 10) as in the prior art, thereby simplifying the outer peripheral shape of the boot mounting portion. Therefore, it is possible to reduce the manufacturing cost by reducing the machining allowance when machining the boot mounting portion and simplifying the machining process. Even in this case, the strong bite action at the acute angle portion ensures the necessary retaining and sealing properties.
[0014]
The acute angle portion can be formed, for example, by making the outer peripheral surface of the groove shoulder portion the first tapered surface whose diameter is reduced at the other end of the boot.
[0015]
If the inclination angle of the first taper surface is too large, the degree of close contact with the fixed portion may be lowered and the sealing performance may be deteriorated. Therefore, the inclination angle is set in the range of 1 to 5 °, more preferably 2 °. It is good.
[0016]
By forming a cylindrical surface on the other end of the boot on the first tapered surface, the amount of deformation of the inner periphery of the fixed portion that is in close contact with the cylindrical surface when the boot band is tightened is reduced compared to the case of only the first tapered surface. The degree of adhesion between the two is increased, and the sealing property can be improved.
[0017]
In addition, a boot mounting portion for mounting a fixing portion provided at one end of the boot, and an engagement groove provided in the boot mounting portion and engageable with a convex portion provided on the inner periphery of the fixing portion of the boot. A constant velocity universal joint in which the boot mounting portion and the boot fixing portion are brought into close contact with each other by a tightening force of a boot band fitted to the outer periphery of the fixing portion of the boot. The taper surface and a circular arc surface continuous to the small diameter side of the second taper surface are connected to the large diameter side of the second taper surface and the circular arc surface respectively to the outer peripheral surface of the boot mounting portion. Protrusions with a cylindrical outer surface are provided on the groove shoulder on the other end side of the boot of the joint groove, and the entire outer peripheral surface on the one end side of the boot with respect to the engaging groove is a cylindrical smooth surface . The circle of the fixed part of the boot on the smooth part It is brought into close contact with Jo inner peripheral surface the same effect can be obtained.
[0019]
By forming the engagement groove with the second tapered surface whose diameter is reduced at the other end of the boot and the circular arc surface continuous therewith, it becomes possible to copy the engagement groove, thereby further reducing the processing cost. Is planned.
[0020]
The inclination angle of the second tapered surface is preferably 25 to 30 °. This inclination angle corresponds to the inclination of a processing tool (turning tip or the like) when processing the engagement groove.
[0021]
By making the groove depth of the engaging groove larger than the height of the convex part and providing a gap between the groove bottom and the convex part, the convex part comes into contact with the bottom of the engaging groove when tightening the boot band and is elastic. It is possible to prevent a situation where the biting property of the acute angle portion is lowered by the deformation and the reaction force corresponding to the deformation.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows a constant velocity universal joint 10 to which a bellows-like boot 20 is attached using a boot band 30. The constant velocity universal joint 10 includes an outer joint member 12 in which a plurality of guide grooves 11 are formed in an axial direction on an inner peripheral surface, an inner joint member 14 in which a plurality of guide grooves 13 are formed in an axial direction on an outer peripheral surface, and a guide groove. 11 and a guide groove 13 are cooperated to form a plurality of balls 15 arranged on a ball track, a retainer 16 for holding the balls 15, and a serration connection (or spline connection) to the inner periphery of the inner joint member 14. The shaft portion 17 is provided.
[0024]
The boot 20 is formed of a flexible material such as a rubber material such as CR or a resin material. For example, in the case of a resin boot, a thermoplastic polyester elastomer (TPEE) having a hardness of 38 ≦ H _D ≦ 50, preferably 38 ≦ H _D ≦ 47, for example, H _D = 47 is used as the resin material. Here, “H _D ” represents the D scale of Shore hardness (according to ASTM).
[0025]
The boot 20 is fixed to the outer peripheries of the outer joint member 12 and the shaft portion 17 using a boot band 30. The boot 20 includes a bellows portion 21 and cylindrical fixing portions 22 and 23 provided on both sides of the bellows portion 21, and the fixing portion 22 provided on one end side of the boot 20, for example, on the large diameter end side. Are fixed to the boot mounting portion 40 a of the outer joint member 12 and the fixing portion 23 provided on the other end side (small diameter end side) is fixed to the boot mounting portion 40 b of the shaft portion 17.
[0026]
2 and 3 show an enlarged view of the boot attachment portion 40a of the outer joint member 12 and the fixing portion 22 on one end side of the boot. Of these, FIG. 2 shows a state before tightening by the boot band 30 and FIG. 3 shows a state after tightening.
[0027]
The boot attachment portion 40 a of the outer joint member 12 is usually provided on the outer peripheral surface of the end portion on the opening side of the outer joint member 12. The boot mounting portion 40a in the illustrated example is formed in a small-diameter cylindrical surface shape in which the outer peripheral surface of the end portion of the outer joint member 12 is partially reduced in diameter, and includes an annular engagement groove 41 in the substantially central portion in the axial direction. is doing. An acute angle portion 42 is formed on the groove shoulder portion (the outer peripheral edge portion of the engagement groove 41) on the other end side (right side of the drawing) of the engagement groove 41. The acute angle portion 42 is an angle formed by the groove shoulder outer peripheral surface 43 and the wall surface 41a (particularly, the outer diameter end portion) on the other end side of the boot of the engagement groove 41. In the present embodiment, the above boot While the other end side wall surface 41a is a circular arc surface in which the tangent line passing through the outer diameter end thereof is orthogonal to the axis XX (see FIG. 1), the groove shoulder outer peripheral surface 43 is reduced in diameter on the other end side of the boot. The case where it is set as the taper surface (1st taper surface) to illustrate is illustrated. If the inclination angle θ ₁ of the first taper surface 43 with respect to the axis XX is excessively large, the degree of adhesion with the fixed portion 22 is lowered, so that the inclination angle is about 1 ° to 5 °, preferably 2 °. (In the drawing, this inclination angle θ ₁ is exaggerated). The maximum outer diameter dimension of the acute angle portion 42 is equal to the outer diameter dimension of the cylindrical smooth surface 44 formed on one end of the boot of the engagement groove 41.
[0028]
The engagement groove 41 is formed by, for example, turning a predetermined portion on the outer periphery of the boot attachment portion 40a. The shape of the engagement groove 41 in the illustrated example is a shape corresponding to the turning tip shape. Specifically, the wall surface 41a on the other end side of the boot is an arc surface corresponding to the rounded shape of the nose of the turning tip, and the wall surface 41b on one end side of the boot is a tapered surface corresponding to the inclination of the turning tip and having a small diameter on the other end side of the boot. (Second taper surface), and both surfaces 41a and 41b are smoothly continuous. By making the tendency groove 41 in such a shape, the engagement groove 41 can be copied, so that the workability can be improved and the manufacturing cost can be reduced.
[0029]
If the R dimension of the wall surface 41a on the other end side of the boot is too small, it is difficult to copy the engagement groove 41, resulting in a decrease in workability and an increase in manufacturing cost. Since it causes a decrease, it is preferable to set it within the range of R = 0.8 to 1.2 mm (preferably 1.2 mm). In addition, the inclination angle θ _{2 with} respect to the axial direction of the second taper surface 41b is set to, for example, 25 to 30 ° corresponding to a triangular tip or a rhombus tip widely used as a turning tip.
[0030]
The fixing portion 22 on one end side of the boot has an annular convex portion 24 fitted in the engaging groove 41 on the inner peripheral surface. In the illustrated example, the convex portion 24 is illustrated as having a circular arc portion 24 a and a tapered portion 24 b corresponding to the shape of the engaging groove 41, but the convex portion 24 is fitted into the engaging groove 41. It can be arbitrarily changed as long as possible.
[0031]
The convex portion 24 has an axial length slightly smaller than the axial length L of the engaging groove 41 so that the convex portion 24 can be smoothly fitted into the engaging groove 41. If the groove depth H of the engagement groove 41 is too small, the convex portion 24 comes into contact with the bottom of the engagement groove 41 at the time of tightening and elastically deforms, and the biting property of the acute angle portion 42 decreases by the reaction force of the deformation. . Therefore, the height h of the convex part 24 must be reduced accordingly, and the effect of fixing the position of the convex part 24 to the engaging groove 41 is reduced. Therefore, the relationship between the groove depth H of the engaging groove 41 and the height h of the convex portion 24 is that the convex portion 24 does not contact the bottom of the engaging groove 41 during tightening, or the acute angle portion 42 bites even when it contacts. Is set so as not to affect. In order to cope with this, in the present embodiment, the groove depth H is set larger than the height h of the convex portion 24 (H> h).
[0032]
In the state where the fixing portion 22 on one end side of the boot is fitted into the boot mounting portion 40a of the outer joint member 12, the convex portion 24 is fitted into the engaging groove 41 and both are positioned, the band groove 25 on the outer periphery of the fixing portion 22 is formed. When the diameter of the fitted boot band 30 is reduced and the fixing portion 22 is fastened to the boot mounting portion 40a, the inner peripheral side of the fixing portion 22 undergoes elastic deformation as shown in FIG. The sharp angle portion 42 bites into the rising portion 24 c of the convex portion 24. The fixing portion 22 is fixed to the boot mounting portion 40a with high retaining and sealing properties by fitting the convex portion 24 and the engaging groove 41 and biting the acute angle portion 42 into the inner periphery of the fixing portion 22. In addition, since the inner peripheral surface of the fixing portion 22 is appropriately in close contact with the outer peripheral surface (the first tapered surface 43 and the smooth surface 44) of the boot mounting portion 40a, good sealing performance can be obtained.
[0033]
In particular, in the present invention, the groove shoulder portion of the engagement groove 41 is formed at an acute angle, so that the acute angle portion 42 is firmly and smoothly bitten into the fixing portion 22, and a higher retaining effect and sealability than this, Good workability is ensured.
[0034]
On the other hand, in the boot mounting portion 40a, the entire outer peripheral region of the boot large end side with respect to the engagement groove 41 is a smooth surface 44, and in the present embodiment, the other end side of the boot with respect to the engagement groove 41. Since the outer peripheral region of the boot mounting portion 40 is formed only by the first tapered surface 43, the outer peripheral shape of the boot mounting portion 40a is simplified as compared with the conventional product (see FIG. 10) having two protrusions 7 on the boot mounting portion 40. be able to. Therefore, a reduction in manufacturing cost can be achieved by reducing the machining allowance and simplifying the machining process. Further, the outer diameter of the boot mounting portion 40a and the outer diameter of the boot 20 can be reduced by the amount corresponding to the absence of the protrusion, and the constant velocity universal joint 10 can be reduced in size and weight, and the material cost and processing cost can be reduced. Reduction can be achieved.
[0035]
In the above embodiment, the case where the fixing portion 22 is attached to the boot attachment portion 40a of the outer joint member 12 has been described. However, the structure shown in FIGS. 2 and 3 is connected to the boot attachment portion 40b of the shaft portion 17 on the other end side of the boot. The same can be applied to the case where the fixing portion 23 on the (small diameter end side) is attached. In this case, the acute angle portion 42 is formed on the groove shoulder portion of the engagement groove on one end side (large diameter end side) of the boot, and the smooth surface 44 is formed on the boot other end side than the engagement groove. In addition to applying the present invention to both the one end side and the other end side of the boot, the present invention may be applied to one end side mounting, and the conventional structure may be applied to the other end side mounting. FIG. 1 shows an example in which the structure shown in FIGS. 2 and 3 is applied to the one end of the boot and the conventional structure shown in FIG. 10 is applied to the other end of the boot.
[0036]
FIG. 4 shows a second embodiment of the present invention in which a cylindrical surface 45 parallel to the axis is formed on the other end side of the boot of the first tapered surface 43. In this case, since the deformation amount of the inner peripheral surface of the fixing portion 22 that is in close contact with the cylindrical surface 45 is smaller than in the case of FIGS. 2 and 3, the degree of adhesion between the two can be increased and the sealing performance can be improved. Since points other than this are the same as the above, the same reference numerals are given to the members common to FIGS. 2 and 3 and the duplicated explanation is omitted.
[0037]
FIG. 5 shows a third embodiment of the present invention in which a protrusion 46 is formed on the groove shoulder on the other end side of the boot of the engagement groove 41 in place of the acute angle portion 42. Also in this case, a cylindrical smooth surface 44 is formed on the outer periphery on the one end side of the boot with respect to the engagement groove 41 as in FIGS. The protrusion 46 includes a cylindrical surface 46a formed on the groove shoulder of the engagement groove 41, and a tapered surface 46b adjacent to the other end of the boot and having a reduced diameter on the other end of the boot. The cylindrical surface 46 a has the same diameter as the smooth surface 44, and after the fastening with the boot band 30, the protrusion 46 bites into the fixed portion 22. Since points other than this are the same as the configurations shown in FIGS. 2 and 3, common members are assigned the same reference numerals, and redundant description is omitted.
[0038]
FIG. 6 shows a boot band 30 that is particularly suitable when resin boots are used. The boot band 30 is formed by bending a band member 31 made of a band-shaped metal material into a ring shape and connecting both ends thereof in a palmed state, and is thicker than the band member 31 on one outer surface of the palm portion 32. The lever member 33 made of a highly rigid metal material is fixed. The band member 31 and the lever member 33 are made of stainless steel, for example.
[0039]
The lever member 33 is barrel-processed to remove burrs and edges at the time of processing, and to improve the surface hardness. Instead of barrel processing, shot blast processing or shot peening processing may be performed. Further, a protrusion 34 is provided on the inner surface of the band member 31. The protrusion 34 is formed by bending a required portion of the band member 31 inward, for example. The protruding portion 34 may be manufactured separately from the band member 31 and fixed to a required portion on the inner side surface of the band member 31.
[0040]
When the fixing portions 22 and 23 are tightened, the lever member 33 is forcibly turned back by utilizing the lever action, and then the lever member 33 is overlaid on the outer surface of the band member 31 as shown in FIG. At the same time, it is fixed with a stopper 35. By turning back the lever member 33, the ring-shaped portion of the band member 31 is reduced in diameter, and a required tightening force (tightening force) is applied to the fixing portions 22 and 23. For example, as shown in FIGS. 7B and 7C, the stopper 35 is obtained by fixing a metal piece having a U-shaped cross section to a predetermined portion of the band member 31. When fixing the lever member 33, both sides thereof are bent and overlapped on the outer surface of the lever member 33. In addition, a stopper is not limited to this, The thing of another structure can be employ | adopted. Further, as a fixing means for the lever member 33, a fixing means such as spot welding may be employed instead of the stopper 35.
[0041]
As shown in FIG. 8, when the lever member 33 is folded, a part of the band member 31 is folded by the folding start point of the lever member 33, and the palm portion 32 overlaps the outer surface of the lever member 33. For this reason, a partial gap is generated in a portion close to the folded portion 31a of the band member 31 (on the side opposite to the folded direction of the lever member 33), and the sealing performance is liable to be lowered at that portion. Therefore, in this embodiment, the protruding portion 3 4 is provided on the inner side surface of the band member 31, and the protruding portion 3 4 is brought into contact with the outer side surface (band groove 25) of the fixing portion 22 so as to close the gap. We are trying to improve. The projecting portion 34 is provided at least at one place, preferably at a position close to the folded portion 31a of the band member 31 when the lever member 33 is folded. Further, the shape, size, and formation position of the protrusion 34 are optimally designed, and the maximum value of the circumferential gap γ between the end surface of the protrusion 34 and the folded portion 31a of the band member 31 is 0 <γ ≦ 1.5 mm. By setting so that it becomes, it will be in a more preferable state for the improvement of sealing performance.
[0042]
The boot band 30 is not limited to the above-described one, and various types of boot bands, for example, an omega (Ω) shaped clamp portion, and a type of band (omega band) that obtains a tightening force by crimping the clamp portion. In addition, a hooking band having a hook for hooking one end of the band member and a hook for hooking the other end can be widely used.
[0043]
【The invention's effect】
According to the present invention, since the biting force to the fixed portion is reinforced by providing an acute angle portion at the groove shoulder portion of the engagement groove, it is possible to improve the sealing property and the retaining property at the mounting portion of the boot. it can. In addition, since the acute angle portion can smoothly bite into the fixed portion, it is possible to improve workability when attaching the boot. The acute angle portion can be easily formed by, for example, forming a tapered surface on the outer peripheral surface of the groove shoulder portion, so that the manufacturing cost can be reduced at a low cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a state when a boot is attached to a constant velocity universal joint.
FIG. 2 is an enlarged cross-sectional view showing a boot attachment portion of the outer joint member and a fixing portion on one end side of the boot (before tightening of the boot band).
FIG. 3 is an enlarged cross-sectional view showing a boot attachment portion of the outer joint member and a fixing portion on one end side of the boot (after tightening of the boot band).
FIG. 4 is a longitudinal sectional view showing a second embodiment of the present invention.
FIG. 5 is a longitudinal sectional view showing a third embodiment of the present invention.
FIG. 6 is a side view of a boot band.
FIG. 7 is a side view (FIG. A) showing a state when a lever member of a boot band is folded, and a cross-sectional view (FIGS. B and C) illustrating a stopper.
FIG. 8 is a cross-sectional view showing a state when the fixing portion of the boot is fastened with a boot band and fixed to the boot attaching portion.
FIG. 9 is a longitudinal sectional view showing a conventional constant velocity universal joint.
FIG. 10 is a longitudinal sectional view showing a conventional constant velocity universal joint.
[Explanation of symbols]
10 constant velocity universal joint 12 outer joint member 20 boot 21 bellows part 22 fixing part 23 fixing part 24 convex part 30 boot band 40a boot attaching part 40b of outer joint member shaft boot attaching part 41 engaging groove 42 acute angle part 43 first One taper surface 44 Smooth surface 45 Cylindrical surface 46 Projection 46a Cylindrical surface

Claims

A boot attachment portion for attaching a fixing portion provided at one end of the boot; and an engagement groove provided in the boot attachment portion and engageable with a convex portion provided on an inner periphery of the fixing portion of the boot. In the constant velocity universal joint that tightly contacts the boot mounting portion and the boot fixing portion by the tightening force of the boot band fitted to the outer periphery of the fixing portion of
The engagement groove is formed by a second tapered surface whose diameter is reduced at the other end of the boot and an arc surface continuous to the small diameter side of the second taper surface, and the second taper surface and the large diameter side of the arc surface are respectively attached to the boot. connecting the outer circumferential surface of the part, of the boot attachment portion, the groove shoulder portion of the boot and the other end side of the engagement groove, and a radially outer end portion of the boot and the other end side of the wall surface of the groove shoulder portion outer peripheral surface and the engaging groove An acute angle part is formed , and the entire outer peripheral surface on one end side of the boot from the engagement groove is a cylindrical smooth surface, and the boot is fixed to the smooth part by the tightening force of the boot band. Constant velocity universal joint in which the cylindrical inner peripheral surface of the part is in close contact .

2. The constant velocity universal joint according to claim 1, wherein the boot attachment portion is provided on the outer joint member.

The constant velocity universal joint according to claim 1, wherein the outer peripheral surface of the groove shoulder portion is a first tapered surface whose diameter is reduced at the other end of the boot.

The constant velocity universal joint according to claim 3 , wherein an inclination angle of the first tapered surface is 1 to 5 °.

The constant velocity universal joint according to claim 3 or 4, wherein a cylindrical surface is formed on the other end side of the boot of the first tapered surface.

A boot attachment portion for attaching a fixing portion provided at one end of the boot; and an engagement groove provided in the boot attachment portion and engageable with a convex portion provided on an inner periphery of the fixing portion of the boot. In the constant velocity universal joint that tightly contacts the boot mounting portion and the boot fixing portion by the tightening force of the boot band fitted to the outer periphery of the fixing portion of
The engagement groove is formed by a second tapered surface whose diameter is reduced at the other end of the boot and an arc surface continuous to the small diameter side of the second taper surface, and the second taper surface and the large diameter side of the arc surface are respectively attached to the boot. The outer peripheral surface of the boot is attached to the shoulder of the other end of the engagement groove on the shoulder portion of the boot groove, and the entire outer peripheral surface on the one end side of the boot with respect to the engagement groove is provided. a cylindrical surface of the smooth surface, the clamping force of the boot band, the constant velocity universal joint are brought into close contact with the cylindrical inner peripheral surface of the fixed portion of the boot to the smooth portion.

The constant velocity universal joint according to any one of claims 1 to 6 , wherein an inclination angle of the second tapered surface is 25 to 30 °.

The constant velocity universal joint according to any one of claims 1 to 7 , wherein a depth of the engaging groove is larger than a height of the convex portion provided on an inner periphery of the fixed portion of the boot .

9. The maximum outer diameter dimension of the groove shoulder portion on the other end side of the boot of the engagement groove in the boot mounting portion is equal to the outer diameter dimension of the smooth surface on the one end side of the boot of the engagement groove. The constant velocity universal joint described in the paragraph.