JP2004347036A

JP2004347036A - Rolling bearing

Info

Publication number: JP2004347036A
Application number: JP2003145222A
Authority: JP
Inventors: Kenji Kotaki; 賢司小滝; Takashi Murai; 隆司村井
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2003-05-22
Filing date: 2003-05-22
Publication date: 2004-12-09

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the wear and torque of a cage and reduce torque by technically controlling the swing operation of rolling elements. <P>SOLUTION: In pocket parts 7 holding the rolling elements 5, the cage comprises only one axial pocket face and the opposite face is opened. The axial pocket faces are arranged aslant to the axial opposite sides to each other correspondingly to the orientation of the inclination of the rolling elements assembled in the circumferential direction in a crossed state. The cage 6 comprises an outer diameter 6a having a dimension larger than the diameter of an intersection between the rotating center axis 5c (line formed by extending the center of the rolling elements) of the rolling elements 5 and the axial pocket face 7b of the pocket part 7 of the cage 6 and an inner diameter 6b having a dimension smaller than the diameter of an intersection between the flat surface parts 5b and the rolling surfaces 5a of the rolling elements 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、ラジアル荷重と両方向のアキシアル荷重、モーメント荷重を受けられる軸受に使用する保持器であり、産業機械，ロボット，医療機器，食品機械，半導体／液晶製造装置，ＤＤモータ（ダイレクトドライブモータ），光学及びオプトエレクトロニクス装置などに使われる。
【０００２】
【従来の技術】
従来、一つの軸受でラジアル荷重と両方向のアキシアル荷重、モーメント荷重を受けられるものとしては、クロスローラ軸受、四点接触玉軸受が知られている。従来のクロスローラ軸受は、内輪と外輪の間に円筒形のころが介在される。四点接触玉軸受は、内輪と外輪の間にボールが介在される。
しかしながら、従来のクロスローラ軸受と四点接触軸受には以下の問題が存在する。
▲１▼クロスローラ軸受は、転動体が円筒形のころで、かつ軌道溝に対して転がり接触面が線接触しているので、トルクが大きい。
▲２▼四点接触玉軸受は、転動体がボールなので、純アキシアル荷重を受ける場合又はラジアル荷重よりアキシアル荷重が優勢な場合、同寸法のクロスローラ軸受よりトルクが小さい一方、アキシアル荷重に対してラジアル荷重が優勢な場合又は純ラジアル荷重を受ける場合、各ボールは軌道溝と四点で接触するため、ボールと軌道溝とのスピン滑りが大きく、トルクが大きいという問題がある。
そこで、このような問題点を解決する新規有用な転がり軸受として、一対の軌道輪間に保持器を介して複数の転動体が組み込まれ、各軌道輪は転動体の半径より大径状の軌道面からなる軌道溝を夫々有し、その中に少なくとも一つの軌道輪は二つの軌道面からなり、各転動体は転がり接触面となる外径が軸方向にも曲率を持ち、円周上に夫々交互に交差状に配されると共に、各転動体の外径が、常に相対する一方の軌道輪の軌道面と他方の軌道輪の軌道面にて夫々一点ずつ合計二点で接触している転がり軸受が提案されている（例えば特許文献１参照。）。
そして、この転がり軸受に組み込まれる保持器には、転動体を保持する為の案内面をポケット部に有しているが、転動体の姿勢（２辺の平面部の角度）が、転動体平面部と保持器ポケット部の案内面とのすきま（案内面すきま）で、回転時に両軸方向に揺動するという特性を持っている。この場合、その転動体の揺動動作を保持器の案内面部分で制御している。
【０００３】
【特許文献１】特開２００１−５０２６４号公報
【０００４】
【発明が解決しようとする課題】
しかしながら、図９（ｂ）に示すように、軸受組み立て時に、転動体３００と保持器４００との案内面すきまによって転動体平面部３０１が、保持器４００の外径４０１と案内面４０２との交点４０３側へ倒れてしまい、その状態で回転及び旋回動作をすると、転動体３００の平面部３０１が保持器外径４０１と案内面４０２との交点４０３での接触摩耗を発生させ、トルク変動が増大し、回転性能に影響を及ぼす虞を有していた。
すなわち、従来のこの種の転がり軸受に組み込まれる保持器４００は、図９（ａ）に示すように、転動体３００の自転中心軸（転動体中心を延長した線）３０２が保持器４００のポケット案内面４０２と交わっていないため、転動体３００の平面部３０１が、保持器外径４０１と案内面４０２との交点４０３で接触してしまうことに起因する。図中、１００は外輪、２００は内輪を示す。
【０００５】
本発明は、従来技術の有するこのような問題点に鑑みなされたものであり、その目的とするところは、転動体の揺動動作を技術的にコントロールし、保持器摩耗の軽減と低トルク化及びトルク減少を図ることである。
【０００６】
【課題を解決するための手段】
上記課題を達成するために本発明がなした技術的手段は、一対の軌道輪間に保持器を介して複数の転動体が組み込まれ、各軌道輪は転動体の半径より大径状の軌道面からなる軌道溝を夫々有し、その中に少なくとも一つの軌道輪は二つの軌道面からなり、各転動体は転がり接触面となる外径が軸方向にも曲率を持ち、円周上に夫々交互に交差状に配されると共に、各転動体の外径が、常に相対する一方の軌道輪の軌道面と他方の軌道輪の軌道面にて夫々一点ずつ合計二点で接触している転がり軸受において、前記保持器の外径は、転動体の平面部がポケット案内面との交点と接触する際、その接点位置が、転動体の自転中心軸（転動体中心を延長した線）と保持器ポケット部との交点の径よりも半径方向に大きい寸法とし、且つ保持器の内径は、転動体の平面部と転動面との交点と、保持器ポケット部の軸方向ポケット面の接点位置の径よりも半径方向に小さい寸法としたことである。
このように、保持器外径寸法を上記の設定寸法とした事により、保持器の外径と軸方向案内面との交点が転動体の平面部を受け、ストッパとなり、転動体の平面部揺動角度を限定することが可能となる。
また、上述の方向と逆方向に転動体が揺動した場合、保持器の軸方向案内面で転動体の平面部と転動面との繋ぎ部（交点部分）を受けるが、保持器の内径寸法が、その内面と繋ぎ部との接点位置よりも小径の設定寸法となっているため、転動体の平面部揺動角度もコントロールできる。
保持器外径寸法を、有効外径寸法よりも半径方向に小径とすると、保持器の外径と軸方向案内面との交点部分への転動体平面部の当たりが強くなり、その交点部分が摩耗を起こしたり、また、これがトルク変動の要因となってしまう。ここで、保持器外径の上限については、保持器外径を半径方向に上げる程、外輪軌道溝が少なくなり、転動体の乗り上げ、接触楕円のはみ出し等の問題があり、考慮が必要である。
また、保持器内径寸法を、有効内径寸法よりも半径方向に大径とすると、保持器の内径と軸方向案内面との交点部分への転動体平面部の当たりが生じる虞があり、その交点部分が摩耗を起こしたり、また、これがトルク変動の要因となってしまう。
以上の事から、保持器外径寸法と保持器内径寸法を限定する事で、転動体の揺動角度を最小限に抑えられ、回転中の転動体に起こるスピン又はスキューを抑制でき、トルク変動の減少化が可能となり、回転性能が上がる。保持器外径部と案内面との交点への転動体平面部の接触の仕方が和らいで接触面圧が下がり、保持器摩耗を抑制出来る。
【０００７】
【発明の実施の形態】
以下、本発明の一実施形態を図に基づいて説明する。なお、本実施形態は本発明の一実施形態にすぎず、これに限定して解釈されるものではなく本発明の範囲内で設計変更可能である。
転がり軸受Ａは、本実施形態では、図１に開示しているように、一体型で成形された軸受軌道輪（軸受外輪）１の内径と、同じく一体型に成形された軸受軌道輪（軸受内輪）２の外径に形成される軌道溝３に、保持器６を介して複数の転動体５，５…が組み込まれて構成されている。なお、図中、８はシール溝で、本実施形態では密封板（シール・シールド）を図示省略しているが、密封板は必要に応じて適宜所望な構成のものを設けることが出来る。なお、軸受寸法・接触角・転動体径あるいは材質などの諸構成は限定されない。
本実施形態によれば、軌道輪としての外輪１と内輪２のいずれも一体型で成形されているため、締結ボルトなどの関連部品を含めた軌道輪の製作コスト・組み立て管理および組み立て費が大幅に削減できた。
軌道溝３は、転動体５の半径よりも大きな半径の軌道面１ａ・１ｂ，２ａ・２ｂにより形成されている。
また、少なくともいずれか一方の軌道輪の軌道溝が、二つの軌道面から構成されているものであればよく本発明の範囲内で適宜選択される。
各軌道面１ａ・１ｂ，２ａ・２ｂの形状は、転動体５の転がりに適切な形状を有しているものであれば、断面アーチ状あるいはＶ字状等任意で、また曲線状あるいは直線状等のいずれであってもよく特に限定されるものではないが、例えば本実施形態では、円心をクロスに配置した両円弧で形成されている、いわゆるゴシックアーチが適用される。
なお、軌道輪１，２のいずれか一方あるいは双方共が幅方向の中央で軸方向に二分割されているタイプであってもよい。また、二分割タイプは、ボルト・リベット４等で一体に組み立てられるものもある。
【０００８】
そして、本実施形態では、内輪２の軌道溝３の一部に、この軌道溝３よりも小さな溝４を凹設している。本実施形態では、内輪軌道面２ａ，２ｂからなる軌道溝３の中心に、周方向に連続する所望深さの断面半円状の小径（例えば溝半径は約０．８ｍｍ）な溝とする。
この溝４は、転動体５の組み込み時における回転用溝として主に使用される。すなわち、後述する転動体５の転動面５ａと平面部５ｂとの繋ぎ部（交点）５ｆを、組み込み時に溝４内に挿入させることによって、転動体５を軌道溝３空間内で回転可能とする。なお、溝４は、その溝４内に潤滑剤を保有させておくことも可能で、軌道面内に備えられる潤滑剤（油、グリースなど）保有機能としての作用もあり、安定した軸受寿命が期待できる。
溝４の形状・径方向深さ・軸方向幅は、軌道面を可能な限り大きく取れるように最小限の大きさにするのが好ましいが、転動体５の転動面５ａと平面部５ｂとの繋ぎ部５ｆが溝４内に一部挿入可能であれば全て本発明の範囲内であり、特に図示形態に限定されず本発明の範囲内で適宜設計変更可能である。例えば４５度程度の面取り程度でもよい。
また、転動体５の周方向配設間隔を考慮すれば、溝４は所望長さをもって周方向に断続して設けてもよく本発明の範囲内である。
なお、軌道面２ａ，２ｂとの繋ぎ部２ｃのエッジを無くしＲ状に形成してもよい。この溝４は、本実施形態では上述の通り内輪２の軌道溝３にのみ設けているが、外輪１の軌道溝３に設けてもよく、また外輪１と内輪２の双方に設けてもよい。
【０００９】
転動体５は、転がり接触面となる転動面（外径）５ａが軸方向に曲率を持ち、かつ軌道面１ａ・１ｂ，２ａ・２ｂの夫々の半径よりも小径の半径を有する任意形状で、該転動体５は、隣接する転動体５が夫々交互に交差状に配されると共に、各転動体５の転動面（外径）５ａが、常に一方の軌道輪１の軌道面１ａ・１ｂと他方の軌道輪２の軌道面２ｂ，２ａにて二点接触している。
転動体５は、例えば本実施形態では図３に拡大して開示しているように、一組の平面部（本実施形態では相対面）５ｂ，５ｂを有する上下切断状玉（玉の上下部分を切断して平面部５ｂ，５ｂを形成した構造のものをいう。以下同じ。）で、該平面部５ｂ，５ｂに垂直する自転中心軸５ｃが夫々交差状となるように夫々の転動体５，５…が組込まれると共に、各転動体５の転動面５ａが、常に一方の軌道輪１の軌道面１ａ，１ｂと他方の軌道輪２の軌道面２ｂ，２ａにて二点接触している。図中５ｆは、転動体５の転動面５ａと平面部５ｂとの繋ぎ部（交点）である。
転動体５は、その上下の切断幅は特に限定されず、また上下の切断割合は、均等あるいは均等でないものであってもよく、本発明の範囲内で任意に選択可能である。すなわち、本実施形態では、平面部５ｂ，５ｂを対称としたが、転動体５の平面部５ｂ，５ｂは、対称であっても非対称であってもよくいずれも本発明の範囲内である。
また、図４に示す非対称の平面部５ｂ，５ｄを有する転動体（上下切断状玉）５の場合、大端側の平面部５ｄが軸受の内輪２に向くように配することで、転動体５の回転がより安定になり、より低トルクを実現することができる。
転動体５の全体形状、相対面５ｂ，５ｂの有無や、転動面５ａにおける軸方向の曲率の大小等は、上記具体的形状に何等限定されるものではなく、本発明の範囲内において任意に変更可能である。すなわち、図示はしないが、例えば、平面部５ｂ，５ｂに代えて、非平行状の両面（平面部）を備え、該両面に垂直する自転中心軸を有するものとしてもよい。
また、図５に示す玉の片側をカット（切断）して一つの平面部（カット面）５ｅを設けた片側カット状玉としたものであってもよい。
また、平面部５ｂ（５ｄ，５ｅ）は、任意形状であって、適宜最適な形状・大きさに変更・選択できる。
【００１０】
転動体５，５…の組込みは、隣り合う転動体５，５における各平面部５ｂ・５ｂ，５ｂ・５ｂに垂直する自転中心軸５ｃ，５ｃが交互に交差状となるようにする。なお、その交差状態は直交状・非直交状のいずれでも構わない。
また、転動体５の交差状に配される方式は、両方のなりで数が同じなら、周方向に交互に配されるものでなくともよく特に限定されない。すなわち、転動体５が１ヶ毎に交差してもよく、１ヶ毎に交差しなくとも両方のなりで数が同じなら、２ヶずつ交差あるいは２ヶ１ヶ１ヶ２ヶ等のように交差していてもよくいずれも本発明の範囲内である。
【００１１】
各転動体５，５の運動は、保持器６で案内される。
保持器６は、図２に示すように、転動体５を保持案内するポケット部（保持部）７…が、周方向に複数個備えられた円環状に形成され、夫々のポケット部７が、周方向に相対する二面のポケット面（周方向案内面）７ａ，７ａを有すると共に、軸方向は一面のポケット面（軸方向に転動体姿勢を安定させる軸方向案内面）７ｂのみ有し、相対する面側は開放（開放面）されており、該軸方向のポケット面７ｂは、互いに交差状に組み込まれる転動体５の傾斜の向きに対応して、互いに軸方向の反対側に傾斜状に配列されている。なお周方向のポケット面７ａの形状は特に限定されず任意である。
軸方向のポケット面７ｂは、転動体５の外輪対向側の平面部５ｂ（図１で左上方に向いている面）を案内するよう外径６ａから内径６ｂにわたり傾斜状に形成されている。よって、ポケット７の外径側開口７ｃより内径側開口７ｄが広く形成されることとなる。
このポケット面７ｂの傾斜角度は任意で、軌道溝３空間内で配される転動体５の角度を考慮して決定される。
本実施形態では、円周上で転動体５…数量と同一数量をもって等間隔で設けられると共に、周方向で隣り合うポケット７の軸方向ポケット面７ｂは、周方向に交互に交差状に配されており、隣り合う各転動体５，５を上述の通り平面部５ｂ・５ｂ，５ｂ・５ｂに垂直する自転中心軸５ｃ，５ｃが夫々交差状になるように交互に組み込み可能とする。
なお、本実施形態では、円周上で転動体５…数量と同一数量のポケット７…が等間隔で、かつ交互に交差状に配されているが、特に限定されず、両方のなりで数が同じなら、２ヶずつ交差あるいは２ヶ１ヶ１ヶ２ヶ等のように交差していても良く本発明の範囲内である。よって、上述した転動体５の配される方式に応じたポケット構成を周方向に設けた保持器とする。
保持器６の案内方式は特に限定されるものではなく、内輪案内でも、外輪案内でも、転動体案内でもよい。また、本実施形態では保持器６を一体型の構成としているが、特に限定されるものではなく、幾つかの部分から形成したものでも良い。
本実施形態の保持器６によれば、外輪１、内輪２と共に組み立てた後、転動体５を保持器６の開放側より軸受軌道溝３空間内へ順次挿入できる。
【００１２】
ここで保持器６は、その外径６ａと内径６ｂを次の寸法に設定し、保持器６の耐摩耗性を上げると共に、点接触にしてトルク変動を少なくすることに本発明の特徴的な構成がある。
すなわち、図１及び図６に示すように、保持器６の外径６ａが、有効外径寸法よりも半径方向に大径とすると共に、保持器６の内径６ｂが、有効内径寸法よりも半径方向に小径とする。
有効外径寸法とは、少なくとも、自転中心軸５ｃ（転動体５の中心を延長した線）が、保持器ポケット部７の軸方向案内面７ｂと直交状に交差する位置Ｐ１を外径とする寸法をいい、この寸法よりも外径６ａ方向に大きい寸法であればよい。
有効内径寸法とは、転動体５の平面部５ｂと転動面５ａとの繋ぎ部（交点）５ｆが、保持器６の軸方向案内面７ｂの内径６ｂ寄りに接する位置Ｐ２を内径とする寸法をいい、この寸法よりも内径６ｂ方向に小さい寸法であればよい。
本実施形態では、図１及び図６に示すように、この有効外径寸法よりも径方向に大きい位置に保持器外径寸法を設定しているため、有効保持器外径寸法を上回っている。また、この有効内径寸法よりも径方向に小さい位置に保持器内径寸法を設定しているため、有効保持器内径寸法を下回っている。
このように、本実施形態では、保持器外径寸法を上記の設定寸法としたことにより、保持器６の外径６ａと軸方向案内面７ｂとの交点６ｃが転動体５の平面部５ｂを受け、ストッパとなり、図１にて符号Ｒ１方向への転動体５の平面部揺動角度を限定することが可能となる。
また、図１にて符号Ｒ２方向へ転動体５が揺動した場合、保持器６の軸方向案内面７ｂで転動体５の平面部５ｂと転動面５ａとの繋ぎ部（交点部分）５ｆを受けるが、その時、保持器６の内径６ｂ寸法が、その内面７ｂと繋ぎ部５ｆとの接点位置よりも半径方向に小径の設定寸法となっているため、軸方向案内面７ｂがストッパとなり、Ｒ２方向への転動体５の平面部揺動角度もコントロールできる。
保持器外径６ａの寸法を、有効外径寸法よりも半径方向に小径とすると、保持器６の外径６ａと軸方向案内面７ｂとの交点６ｃ部分への転動体平面部５ｂの当たりが強くなり、その交点６ｃ部分が摩耗を起こしたり、また、これがトルク変動の要因となってしまう。
保持器内径寸法を、有効内径寸法よりも半径方向に大径とすると、保持器内径６ｂと軸方向案内面７ｂとの交点６ｄ部分への転動体平面部５ｂの当たりが生じる虞があり、その交点６ｄ部分が摩耗を起こしたり、また、これがトルク変動の要因となってしまう。
図７に保持器の外内径寸法と保持器摩耗との関係を示す。
【００１３】
図８に従来型保持器（図９）を組み込んだ軸受（以下、従来軸受という）と本発明保持器を組み込んだ軸受（以下、本発明軸受という）での軸受回転トルク比較試験の概略を示す。
当該試験においては、保持器以外の軸受仕様、すなわち外輪、内輪、転動体は、従来軸受と本発明軸受とも共通とした。
図中、△印で示したものが従来軸受の変動量を示し、○印で示したものが本発明軸受の変動量を示す。
［試験条件］
回転数：１１．６７ｓ^−１（７００ｒｐｍ）
モーメント荷重：４０Ｎ・ｍ
予圧すきま：−０．００７ｍｍ
図８によれば、本発明軸受の方が、従来軸受よりも低トルクで、かつトルク変動量が少ないという試験結果が得られた。
【００１４】
本実施形態は予圧品であるが、すきま品でもよいことは言うまでもない。
転動体と軌道面との間における予圧の付与される状態は特に限定されず、すなわち、製造段階で予圧が付与されても付与されなくてもよくいずれも本発明の範囲内である。
【００１５】
これら軸受の軌動輪１，２と転動体５の材質としては、通常軸受鋼が用いられるが、使用環境に応じて耐食性や、耐熱性を向上させる場合にはステンレス鋼やセラミック等が適宜選択される。
また保持器６の材料としては、もみ抜き保持器、プレス保持器、樹脂保持器等が適宜選択されるので、例えば黄銅や鉄等の金属や、例えばポリアミド６６（ナイロン６６）・ポリフェニレンサルファイド（ＰＰＳ）等の合成樹脂が本発明の範囲内で選ばれる。
【００１６】
この実施形態によれば、転動体５の外径５ａが相対する外輪１の軌道面１ａと内輪２の軌道面２ｂに夫々点接触（接触点を１１，１１で示す）し、隣接する転動体５が外輪１の軌道面１ｂと内輪２の軌道面２ａに夫々点接触（接触点は図示省略）する。転動体５，５の接触角交互に交差するので、一つの軸受でラジアル荷重と両方向のアキシアル荷重、モーメント荷重を受けることができる。
また、転動体５が軌道面１ａ，２ｂで、もう一方の転動体５が軌道面１ｂ，２ａで夫々二箇所しか点接触（１１・１１）していないので、従来の四点接触軸受における大きなスピンを除くことができる。
さらに、転動体５，５と外内輪１，２との接触形式は一般の玉軸受と同じなので、クロスローラに比べ、転がり抵抗が低く、低トルクを実現することができる。
【００１７】
【発明の効果】
本発明は、上述の通りの構成としたため、転動体の揺動動作を技術的にコントロールし、保持器摩耗の軽減と低トルク化及びトルク減少を図ることができた。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す概略縦断面図。
【図２】保持器の一実施形態を示す部分拡大平面図。
【図３】転動体の一実施例を示す拡大斜視図。
【図４】転動体の他の実施形態を示す拡大斜視図。
【図５】転動体の他の実施形態を示す拡大斜視図。
【図６】本発明の一実施形態を示す概略縦断面図で、保持器ポケット部の案内面に転動体の繋ぎ部が接触している状態を示す。
【図７】保持器外径寸法・内径寸法による保持器摩耗との関係を示す図。
【図８】従来軸受と本発明軸受での軸受回転トルク比較試験の概略を示す図。
【図９】（ａ）は従来の保持器を組み込んだ軸受の概略縦断面図、（ｂ）は転動体の平面部が保持器の外面と案内面との交点部分で接触している状態を示す概略図。
【符号の説明】
１：外輪
２：内輪
３：軌道溝
５：転動体
５ａ：外径（転動面）
５ｂ：平面部（相対面）
６：保持器
６ａ：外径
６ｂ：内径
７ｂ：軸方向案内面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cage used for a bearing capable of receiving a radial load, an axial load in both directions, and a moment load, and is used for an industrial machine, a robot, a medical device, a food machine, a semiconductor / liquid crystal manufacturing device, a DD motor (direct drive motor). , Optical and optoelectronic devices.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a single bearing capable of receiving a radial load, an axial load and a moment load in both directions, a cross roller bearing and a four-point contact ball bearing are known. In a conventional cross roller bearing, a cylindrical roller is interposed between an inner ring and an outer ring. In a four-point contact ball bearing, a ball is interposed between an inner ring and an outer ring.
However, conventional cross roller bearings and four-point contact bearings have the following problems.
{Circle around (1)} The cross roller bearing has a large torque because the rolling element is a cylindrical roller and the rolling contact surface is in linear contact with the raceway groove.
(2) In a four-point contact ball bearing, since the rolling element is a ball, when receiving a pure axial load or when the axial load is dominant over the radial load, the torque is smaller than that of a cross roller bearing of the same size, but the When the radial load is predominant or when a pure radial load is applied, each ball comes into contact with the raceway groove at four points, so that there is a problem that the spin sliding between the ball and the raceway groove is large and the torque is large.
Therefore, as a new and useful rolling bearing that solves such a problem, a plurality of rolling elements are incorporated between a pair of races via a retainer, and each race has a raceway having a diameter larger than the radius of the rolling race. Each of the rolling elements has two raceway surfaces, and each rolling element has a rolling contact surface with an outer diameter that also has a curvature in the axial direction. Each of the rolling elements is arranged alternately in an intersecting manner, and the outer diameter of each rolling element is always in contact with the raceway surface of one of the raceways and the raceway surface of the other raceway at two points in total. BACKGROUND ART Rolling bearings have been proposed (for example, see Patent Document 1).
The cage incorporated in the rolling bearing has a guide surface for holding the rolling element in the pocket portion, and the attitude of the rolling element (the angle of the plane portion on two sides) is determined by the rolling element plane. The clearance between the guide portion and the guide surface of the retainer pocket portion (guide surface clearance) has a characteristic that it swings in both axial directions during rotation. In this case, the swinging operation of the rolling element is controlled by the guide surface portion of the cage.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-50264
[Problems to be solved by the invention]
However, as shown in FIG. 9B, at the time of assembling the bearing, the rolling element flat portion 301 is moved by the guide surface clearance between the rolling element 300 and the retainer 400 so that the intersection between the outer diameter 401 of the retainer 400 and the guide surface 402 is formed. If the roller 300 falls down to the side 403 and rotates and turns in that state, the flat portion 301 of the rolling element 300 generates contact wear at the intersection 403 between the outer diameter 401 of the cage and the guide surface 402, and torque fluctuation increases. However, there is a fear that the rotation performance is affected.
That is, as shown in FIG. 9A, a cage 400 incorporated in this type of conventional rolling bearing has a rotation center axis (a line extending from the center of the rolling body) 302 of the rolling body 300 and a pocket of the cage 400. Since it does not intersect with the guide surface 402, the flat portion 301 of the rolling element 300 comes into contact at an intersection 403 between the cage outer diameter 401 and the guide surface 402. In the figure, 100 indicates an outer ring, and 200 indicates an inner ring.
[0005]
The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to technically control the swinging operation of a rolling element to reduce cage wear and reduce torque. And to reduce the torque.
[0006]
[Means for Solving the Problems]
Technical means achieved by the present invention to achieve the above object is that a plurality of rolling elements are incorporated between a pair of races via a retainer, and each race has a raceway having a diameter larger than the radius of the rolling bodies. Each of the rolling elements has two raceway surfaces, and each rolling element has a rolling contact surface with an outer diameter that also has a curvature in the axial direction. Each of the rolling elements is arranged alternately in an intersecting manner, and the outer diameter of each rolling element is always in contact with the raceway surface of one of the raceways and the raceway surface of the other raceway at two points in total. In the rolling bearing, the outer diameter of the retainer is such that when the flat portion of the rolling element contacts the intersection with the pocket guide surface, the contact position is determined by the rotation center axis of the rolling element (a line extending the center of the rolling element). The dimension in the radial direction is larger than the diameter of the intersection with the cage pocket, and the inner diameter of the cage. Is that the rolling and the intersection between the plane portion and the rolling surface of the rolling elements, and small dimensions in the radial direction than the diameter of the contact position in the axial direction pocket surface of the cage pockets.
As described above, by setting the outer diameter of the cage to the above-described set size, the intersection between the outer diameter of the cage and the axial guide surface receives the flat portion of the rolling element and serves as a stopper, and the flat portion of the rolling element swings. The movement angle can be limited.
When the rolling element swings in a direction opposite to the above-described direction, the axial guide surface of the retainer receives a connecting portion (intersection) between the flat portion of the rolling element and the rolling surface. Since the size is smaller than the contact point between the inner surface and the connecting portion, the swing angle of the flat portion of the rolling element can be controlled.
If the outer diameter of the cage is made smaller in the radial direction than the effective outer diameter, the contact of the rolling element plane portion with the intersection of the outer diameter of the cage and the axial guide surface becomes stronger, and the intersection becomes Wear occurs, and this causes torque fluctuation. Here, as for the upper limit of the cage outer diameter, as the cage outer diameter is increased in the radial direction, the outer ring raceway groove is reduced, and there are problems such as running up of the rolling element, protrusion of the contact ellipse, and the like. .
Also, if the inner diameter of the retainer is made larger in the radial direction than the effective inner diameter, the rolling element flat portion may hit the intersection of the inner diameter of the retainer and the axial guide surface. The parts may be worn, and this may cause torque fluctuation.
From the above, by limiting the outer diameter of the cage and the inner diameter of the cage, the swing angle of the rolling element can be minimized, and the spin or skew that occurs on the rotating rolling element can be suppressed, and torque fluctuations can be suppressed. Can be reduced, and the rotation performance increases. The manner of contact of the rolling element flat portion with the intersection between the cage outer diameter portion and the guide surface is reduced, so that the contact surface pressure is reduced and wear of the cage can be suppressed.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that this embodiment is merely an embodiment of the present invention, and is not to be construed as being limited to the embodiment, and the design can be changed within the scope of the present invention.
In the present embodiment, as shown in FIG. 1, the rolling bearing A has an inner diameter of an integrally formed bearing race ring (bearing outer ring) 1 and a similarly formed integrally formed bearing race ring (bearing). A plurality of rolling elements 5, 5,... Are incorporated into a raceway groove 3 formed on the outer diameter of the inner ring 2 via a retainer 6. In the drawings, reference numeral 8 denotes a seal groove, and a sealing plate (seal / shield) is not shown in the present embodiment, but a sealing plate having a desired configuration can be appropriately provided as needed. Various configurations such as bearing dimensions, contact angles, rolling element diameters, and materials are not limited.
According to the present embodiment, since both the outer ring 1 and the inner ring 2 as the race rings are integrally formed, the production cost, the assembly management and the assembly cost of the race rings including the related parts such as the fastening bolts are large. Was reduced to
The raceway groove 3 is formed by raceway surfaces 1 a and 1 b and 2 a and 2 b having a radius larger than the radius of the rolling element 5.
In addition, it is sufficient that at least one of the raceways has a raceway groove composed of two raceway surfaces, and is appropriately selected within the scope of the present invention.
The shape of each raceway surface 1a, 1b, 2a, 2b is arbitrary, such as a cross-section arch shape or a V-shape, as long as it has a shape suitable for rolling of the rolling element 5, and a curved or linear shape. For example, in the present embodiment, a so-called Gothic arch, which is formed by two arcs each having a circular center arranged in a cross, is applied.
One or both of the races 1 and 2 may be of a type that is axially divided into two at the center in the width direction. Some of the two-split types are assembled integrally with bolts and rivets 4 or the like.
[0008]
In the present embodiment, a groove 4 smaller than the raceway groove 3 is formed in a part of the raceway groove 3 of the inner race 2. In the present embodiment, a groove having a semicircular cross-section (for example, a groove radius of about 0.8 mm) having a desired depth in a circumferential direction and having a desired depth is formed at the center of the raceway groove 3 formed by the inner raceway surfaces 2a and 2b.
The groove 4 is mainly used as a groove for rotation when the rolling element 5 is assembled. That is, by inserting a connecting portion (intersection) 5f between a rolling surface 5a and a plane portion 5b of the rolling element 5 described later into the groove 4 at the time of assembling, the rolling element 5 can be rotated in the raceway groove 3 space. I do. The groove 4 can also hold a lubricant in the groove 4 and also has a function as a lubricant (oil, grease, etc.) holding function provided in the raceway surface, so that a stable bearing life is provided. Can be expected.
The shape, radial depth and axial width of the groove 4 are preferably minimized so that the raceway surface can be as large as possible, but the rolling surface 5a and the flat portion 5b of the rolling element 5 If the connecting portion 5f can be partially inserted into the groove 4, it is entirely within the scope of the present invention, and the design is not particularly limited to the illustrated embodiment but can be appropriately changed within the scope of the present invention. For example, a chamfer of about 45 degrees may be used.
Further, in consideration of the interval between the rolling elements 5 in the circumferential direction, the grooves 4 may be provided in the circumferential direction with a desired length, which is within the scope of the present invention.
The edge of the connecting portion 2c with the raceway surfaces 2a and 2b may be formed in an R shape without the edge. In this embodiment, the groove 4 is provided only in the raceway groove 3 of the inner ring 2 as described above, but may be provided in the raceway groove 3 of the outer ring 1 or may be provided in both the outer ring 1 and the inner ring 2. .
[0009]
The rolling element 5 has an arbitrary shape in which a rolling surface (outer diameter) 5a serving as a rolling contact surface has a curvature in the axial direction and has a radius smaller than the radius of each of the raceway surfaces 1a, 1b, 2a, 2b. The rolling elements 5 are arranged such that adjacent rolling elements 5 are alternately arranged in an intersecting manner, and the rolling surface (outer diameter) 5a of each rolling element 5 is always the raceway surface 1a 1b and the raceway surfaces 2b and 2a of the other raceway ring 2 make two-point contact.
The rolling element 5 is, for example, a vertically cut ball (a vertical part of a ball) having a pair of flat portions (relative surfaces in the present embodiment) 5b, 5b as disclosed in this embodiment in an enlarged manner in FIG. Are cut to form flat portions 5b, 5b. The same applies to the following.), And each rolling element 5 is arranged such that a rotation center axis 5c perpendicular to the flat portions 5b, 5b crosses each other. , 5... Are assembled, and the rolling surface 5a of each rolling element 5 always comes into two-point contact with the raceways 1a, 1b of one race 1 and the raceways 2b, 2a of the other race 2. I have. 5f in the figure is a connecting portion (intersection) between the rolling surface 5a of the rolling element 5 and the flat portion 5b.
The upper and lower cutting widths of the rolling element 5 are not particularly limited, and the upper and lower cutting ratios may be equal or unequal, and can be arbitrarily selected within the scope of the present invention. That is, in the present embodiment, the plane portions 5b, 5b are symmetric, but the plane portions 5b, 5b of the rolling element 5 may be symmetric or asymmetric, and both are within the scope of the present invention.
In the case of a rolling element (vertical cut ball) 5 having asymmetrical flat parts 5b and 5d shown in FIG. 4, the rolling element is arranged such that the large end side flat part 5d faces the inner ring 2 of the bearing. 5 is more stable, and lower torque can be realized.
The overall shape of the rolling element 5, the presence or absence of the relative surfaces 5b, 5b, and the magnitude of the axial curvature of the rolling surface 5a are not limited to the above specific shape at all, and are arbitrary within the scope of the present invention. Can be changed to That is, although not shown, for example, instead of the plane portions 5b, 5b, non-parallel surfaces (plane portions) may be provided, and a rotation center axis perpendicular to the both surfaces may be provided.
Alternatively, one side of the ball shown in FIG. 5 may be cut (cut) to form a one-side cut ball provided with one flat portion (cut surface) 5e.
The flat portion 5b (5d, 5e) has an arbitrary shape, and can be appropriately changed and selected to an optimum shape and size.
[0010]
The rolling elements 5, 5,... Are assembled so that the rotation center axes 5c, 5c perpendicular to the plane portions 5b, 5b, 5b, 5b of the adjacent rolling elements 5, 5 alternately cross each other. The crossing state may be either orthogonal or non-orthogonal.
In addition, the method of arranging the rolling elements 5 in an intersecting manner is not particularly limited, as long as the numbers are the same in both cases, as long as they are not alternately arranged in the circumferential direction. That is, the rolling elements 5 may intersect one by one, and if they do not intersect one by one, and if the numbers are the same in both cases, they intersect two by two or two by one or two. They may intersect and all are within the scope of the present invention.
[0011]
The movement of each rolling element 5, 5 is guided by a retainer 6.
As shown in FIG. 2, the retainer 6 is formed in an annular shape in which a plurality of pocket portions (retaining portions) 7 for retaining and guiding the rolling elements 5 are provided in a circumferential direction. It has two pocket surfaces (circumferential guide surfaces) 7a, 7a facing each other in the circumferential direction, and has only one pocket surface (axial guide surface for stabilizing the rolling element posture in the axial direction) 7b in the axial direction. The opposing surfaces are open (open surfaces), and the axial pocket surfaces 7b are inclined toward the opposite sides in the axial direction so as to correspond to the directions of inclination of the rolling elements 5 incorporated in an intersecting manner. Are arranged. The shape of the pocket surface 7a in the circumferential direction is not particularly limited and is arbitrary.
The axial pocket surface 7b is formed so as to be inclined from the outer diameter 6a to the inner diameter 6b so as to guide the flat portion 5b (the surface facing upward and left in FIG. 1) of the rolling element 5 on the outer ring facing side. Therefore, the inner diameter side opening 7d is formed wider than the outer diameter side opening 7c of the pocket 7.
The inclination angle of the pocket surface 7b is arbitrarily determined in consideration of the angle of the rolling elements 5 disposed in the space of the raceway groove 3.
In this embodiment, the same number of rolling elements 5 as the number of rolling elements 5 are provided on the circumference at equal intervals, and the axial pocket surfaces 7b of the pockets 7 adjacent in the circumferential direction are alternately arranged in the circumferential direction so as to intersect. As described above, the rolling elements 5 adjacent to each other can be alternately assembled such that the rotation center axes 5c, 5c perpendicular to the plane portions 5b, 5b, 5b, 5b cross each other.
In the present embodiment, the same number of the rolling elements 5 as the number of the pockets 7 are arranged at regular intervals and alternately in an intersecting manner on the circumference. However, the number of the pockets 7 is not particularly limited. If they are the same, they may intersect each other, such as two by two or two by one, which is within the scope of the present invention. Therefore, a cage provided in the circumferential direction has a pocket configuration corresponding to the method of disposing the rolling elements 5 described above.
The guide system of the retainer 6 is not particularly limited, and may be inner ring guide, outer ring guide, or rolling element guide. Further, in the present embodiment, the retainer 6 has an integral structure, but the retainer 6 is not particularly limited and may be formed from several parts.
According to the cage 6 of the present embodiment, after assembling with the outer ring 1 and the inner ring 2, the rolling elements 5 can be sequentially inserted into the space of the bearing raceway groove 3 from the open side of the cage 6.
[0012]
The characteristic feature of the present invention is that the cage 6 has its outer diameter 6a and inner diameter 6b set to the following dimensions to increase the wear resistance of the cage 6 and reduce the torque fluctuation by making point contact. There is a configuration.
That is, as shown in FIGS. 1 and 6, the outer diameter 6a of the retainer 6 is radially larger than the effective outer diameter, and the inner diameter 6b of the retainer 6 is larger than the effective inner diameter. Make the diameter smaller in the direction.
The effective outer diameter dimension is defined as an outer diameter at least a position P1 at which a rotation center axis 5c (a line extending the center of the rolling element 5) intersects the axial guide surface 7b of the cage pocket portion 7 at right angles. A dimension refers to a dimension larger than this dimension in the direction of the outer diameter 6a.
The effective inner diameter dimension is a dimension having an inner diameter at a position P2 at which a connecting portion (intersection) 5f between the flat surface portion 5b of the rolling element 5 and the rolling surface 5a comes into contact with the axial guide surface 7b of the retainer 6 near the inner diameter 6b. Any size may be used as long as it is smaller than this dimension in the direction of the inner diameter 6b.
In the present embodiment, as shown in FIGS. 1 and 6, the retainer outer diameter is set at a position radially larger than the effective outer diameter, and therefore exceeds the effective retainer outer diameter. . In addition, since the retainer inner diameter is set at a position radially smaller than the effective inner diameter, it is smaller than the effective retainer inner diameter.
As described above, in the present embodiment, the intersection 6c between the outer diameter 6a of the retainer 6 and the axial guide surface 7b sets the flat portion 5b of the rolling element 5 by setting the outer diameter of the retainer to the above-described set dimension. 1 and serves as a stopper, which makes it possible to limit the plane part swing angle of the rolling element 5 in the direction of the symbol R1 in FIG.
When the rolling element 5 swings in the direction R2 in FIG. 1, a joint (intersection) 5f between the flat portion 5b of the rolling element 5 and the rolling surface 5a on the axial guide surface 7b of the retainer 6 is formed. At this time, since the inner diameter 6b of the retainer 6 is smaller in the radial direction than the contact position between the inner surface 7b and the connecting portion 5f, the axial guide surface 7b serves as a stopper. The swing angle of the flat part of the rolling element 5 in the R2 direction can also be controlled.
Assuming that the outer diameter 6a of the cage is smaller in the radial direction than the effective outer diameter, the rolling element flat portion 5b contacts the intersection 6c between the outer diameter 6a of the cage 6 and the axial guide surface 7b. As a result, the intersection 6c becomes worn, and this causes torque fluctuation.
If the inner diameter of the retainer is made larger in the radial direction than the effective inner diameter, the rolling element flat portion 5b may hit the intersection 6d between the inner diameter 6b of the retainer and the axial guide surface 7b. Wear occurs at the intersection 6d, and this causes torque fluctuation.
FIG. 7 shows the relationship between the outer and inner diameters of the cage and the wear of the cage.
[0013]
FIG. 8 shows an outline of a bearing torque comparison test between a bearing incorporating the conventional cage (FIG. 9) (hereinafter, referred to as conventional bearing) and a bearing incorporating the cage of the present invention (hereinafter, referred to as the present bearing). .
In the test, the bearing specifications other than the cage, that is, the outer ring, the inner ring, and the rolling elements were common to the conventional bearing and the bearing of the present invention.
In the figure, the symbols indicated by Δ indicate the variation of the conventional bearing, and the symbols indicated by ○ indicate the variation of the bearing of the present invention.
[Test condition]
Revolution: 11.67 s ^-1 (700 rpm)
Moment load: 40 N ・ m
Preload clearance: -0.007mm
According to FIG. 8, a test result was obtained that the bearing of the present invention had lower torque and a smaller amount of torque fluctuation than the conventional bearing.
[0014]
Although the present embodiment is a preload product, it goes without saying that a clearance product may be used.
The state in which the preload is applied between the rolling element and the raceway surface is not particularly limited, that is, the preload may or may not be applied in the manufacturing stage, and both are within the scope of the present invention.
[0015]
As the material of the race wheels 1 and 2 and the rolling elements 5 of these bearings, usually bearing steel is used. In order to improve the corrosion resistance and heat resistance in accordance with the use environment, stainless steel or ceramic is appropriately selected. You.
As the material of the retainer 6, an extruded retainer, a press retainer, a resin retainer, and the like are appropriately selected. For example, metals such as brass and iron, and polyamide 66 (nylon 66) and polyphenylene sulfide (PPS) are used. ) Are selected within the scope of the present invention.
[0016]
According to this embodiment, the outer diameter 5a of the rolling element 5 makes point contact with the raceway surface 1a of the outer race 1 and the raceway surface 2b of the inner race 2 (the contact points are indicated by 11 and 11), respectively. 5 makes point contact with the raceway surface 1b of the outer race 1 and the raceway surface 2a of the inner race 2 (contact points are not shown). Since the contact angles of the rolling elements 5 and 5 intersect alternately, a single bearing can receive a radial load and an axial load and a moment load in both directions.
In addition, since the rolling element 5 has only two point contacts (11, 11) on the raceway surfaces 1a and 2b and the other rolling element 5 on the raceway surfaces 1b and 2a, a large size in the conventional four-point contact bearing. Spin can be eliminated.
Further, since the contact form between the rolling elements 5 and 5 and the outer and inner rings 1 and 2 is the same as that of a general ball bearing, the rolling resistance is lower and a lower torque can be realized as compared with a cross roller.
[0017]
【The invention's effect】
Since the present invention has the above-described configuration, the swinging operation of the rolling element is technically controlled, so that the wear of the cage can be reduced, the torque can be reduced, and the torque can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an embodiment of the present invention.
FIG. 2 is a partially enlarged plan view showing an embodiment of the retainer.
FIG. 3 is an enlarged perspective view showing one embodiment of a rolling element.
FIG. 4 is an enlarged perspective view showing another embodiment of a rolling element.
FIG. 5 is an enlarged perspective view showing another embodiment of a rolling element.
FIG. 6 is a schematic longitudinal sectional view showing one embodiment of the present invention, and shows a state in which a connecting portion of a rolling element is in contact with a guide surface of a cage pocket portion.
FIG. 7 is a diagram showing a relationship between cage outer diameter and inner diameter and cage wear.
FIG. 8 is a diagram schematically illustrating a bearing rotational torque comparison test between a conventional bearing and a bearing of the present invention.
9A is a schematic longitudinal sectional view of a bearing incorporating a conventional cage, and FIG. 9B shows a state in which a flat portion of a rolling element is in contact with an intersection between an outer surface of the cage and a guide surface. FIG.
[Explanation of symbols]
1: outer ring 2: inner ring 3: raceway groove 5: rolling element 5a: outer diameter (rolling surface)
5b: flat part (relative surface)
6: cage 6a: outer diameter 6b: inner diameter 7b: axial guide surface

Claims

A plurality of rolling elements are incorporated between a pair of races via a retainer, and each race has a raceway groove having a raceway surface having a diameter larger than the radius of the rolling body, and at least one raceway is provided therein. The ring consists of two raceways,
The outer diameter of each rolling element as a rolling contact surface also has a curvature in the axial direction, and is guided by the axial pocket surface of each pocket portion in the circumferential direction of the cage, and is alternately arranged on the circumference alternately. Along with
In a rolling bearing, the outer diameter of each rolling element is always in contact at one point each on the raceway surface of one raceway ring and the raceway surface of the other raceway that are opposed to each other,
The outer diameter of the retainer is radially larger than the diameter of the intersection of the rotation center axis of the rolling element and the axial pocket surface of the retainer pocket,
A rolling bearing wherein the inner diameter of the retainer is radially smaller than the intersection of the flat portion and the rolling surface of the rolling element and the diameter of the contact point on the axial pocket surface of the retainer pocket. .

The cage has only one axial direction pocket surface in each pocket portion holding the rolling element, and the opposite surface side is open, and the axial direction pocket surfaces are incorporated in the circumferential direction so as to intersect with each other. The rolling bearing according to claim 1, wherein the rolling bearings are arranged in an inclined manner on opposite sides of the axial direction in correspondence with the direction of inclination of the rolling elements to be rolled.

The rolling bearing according to claim 2, wherein the rolling element has at least one flat portion, and the flat portion contacts an axial pocket surface of the retainer.