JP4110793B2

JP4110793B2 - Rolling bearing

Info

Publication number: JP4110793B2
Application number: JP2002043561A
Authority: JP
Inventors: 哲雄池田; 知宏春田
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 2002-02-20
Filing date: 2002-02-20
Publication date: 2008-07-02
Anticipated expiration: 2022-02-20
Also published as: JP2003239987A

Description

【０００１】
【発明の属する技術分野】
本発明は、ハードディスクドライブ（ＨＤＤ）装置などの磁気記録装置等に用いられ、ディスク媒体等の回転体を支承する転がり軸受に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
例えばＨＤＤ装置に使用される転がり軸受では、スピンドルモータなどによる磁気ディスクの高速回転を高精度に支承するため、回転・音響性能や耐フレッチング性能、耐摩耗性能等に優れたセラミックス材料からなる転動体を使用することがある。このセラミックス材料は、一般的に、窒化ケイ素又はジルコニアなどの非導電性材料、すなわち絶縁材であり、従って、この従来の転がり軸受の内外輪間は電気的に絶縁されている。それゆえ、この従来の転がり軸受をＨＤＤ装置に用いた場合、外輪（回転輪）と共に回転する磁気ディスク上の電荷は逃げ場が無く、蓄積される。その結果、帯電した磁気ディスクにより電気的にヘッドが引き付けられて接触するヘッドクラッシュ等の不具合を生じる恐れがあった。このようなヘッドクラッシュ等を防ぐために、アース手段としての磁性流体シールを軸受や装置に取り付け、帯電した電荷を逃がすことが提案されているが、磁性流体シールだけでは帯電防止に不十分なことがあり、さらには軸受や装置構成が複雑なものとなった。
また、導電性材料を添加し、一定の導電性を付与したセラミックス材料も提案されているが、十分な導電性と耐フレッチング、耐摩耗性等の強度を両立させるのは困難であり、後者を優先した場合には、絶縁材とは言えないまでも、難導電材であり、上記ヘッドクラッシュ等の不具合を解消するには至らない。ここで、上記難導電材とは、体積抵抗率（ＪＩＳ、Ｋ６９１１に記載）が１０⁶Ω・ｃｍより大きいものとする。
【０００３】
また、上記のような従来の転がり軸受では、近年、ポリアミド樹脂などの合成樹脂製の保持器が使用されている。ところが、この合成樹脂自体が元々帯電し易い材料であるため、保持器の帯電量、ひいては軸受の帯電量を増加させる。この結果、軸受は、帯電した電荷によって大気中の塵埃等の異物を吸着し易くなり、軸受回転時に異音（ゴミ音）を生じ、その音響特性を著しく低下させることがあった。
【０００４】
上記のような従来の問題点に鑑み、本発明は、非導電性材料または難導電性材料からなる転動体を備えた転がり軸受において、当該軸受の帯電を十分に抑制することができ、よって帯電に起因する軸受性能の低下などを防ぐことができる転がり軸受を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明の転がり軸受は、内輪及び外輪と、前記内輪と外輪との間に転動自在に設けられた複数の転動体と、前記複数の転動体を周方向に沿って所定間隔に保持する円環状の保持器とを備えた転がり軸受であって、
前記内輪、外輪、及び保持器が導電性材料により構成され、かつ前記転動体が非導電性材料または難導電性材料により構成されているとともに、
前記保持器の内周側の一部及び外周側の一部に、当該保持器の偏芯に伴って前記内輪の外周面及び前記外輪の内周面にそれぞれ接触して内外輪間を電気的に導通させる第１及び第２の通電部を設け、前記第１通電部と第２通電部の周方向位置を互いにずらしたことを特徴とするものである（請求項１）。
【０００６】
上記のように構成された転がり軸受では、内外輪及び保持器が導電性材料により構成され、かつ保持器に設けた上記第１及び第２の通電部がその保持器の偏芯に伴って内輪の外周面及び外輪の内周面にそれぞれ接触したときに、当該保持器を介して内外輪間が電気的に導通する。従って、転動体が鋼製の場合とほぼ同様な帯電防止効果が得られ、軸受の帯電を十分に抑制することができる。また、導電性材料によって保持器を構成していることから、合成樹脂からなる従来例と異なり、保持器自体の帯電を防止し、軸受の帯電量の増加を防ぐことができ、帯電による異物の吸着を抑えることができる。
【０００７】
また、上記転がり軸受（請求項１）において、前記保持器が、環状の基部と、この基部から周方向に沿って所定間隔に突設された複数の柱部と、前記柱部の相互間に設けられ、前記複数の転動体をそれぞれ保持する複数のポケットとを備え、
前記基部の内周及び外周を互いに位相が異なる楕円形状に形成するとともに、前記基部内周の楕円形状での短径部分を前記第１の通電部として構成し、かつ前記基部外周の楕円形状での長径部分を前記第２の通電部として構成してもよい（請求項２）。
この場合、上記短径部分及び長径部分がそれぞれ内輪外周面及び外輪内周面に接触することにより、保持器を介して内外輪間を電気的に導通させる。
【０００８】
また、上記転がり軸受（請求項１）において、前記第１の通電部が、前記保持器の内周面から径方向内方側に突出した第１の突起部により構成され、かつ前記第２の通電部が、前記保持器の外周面から径方向外方側に突出した第２の突起部により構成されてもよい（請求項３）。
この場合、上記各突起部が対応する内輪外周面及び外輪内周面に接触することにより、保持器を介して内外輪間を電気的に導通させる。
【０００９】
また、本発明の転がり軸受は、内輪及び外輪と、前記内輪と外輪との間に転動自在に設けられた複数の転動体と、前記複数の転動体を周方向に沿って所定間隔に保持する円環状の保持器とを備えた転がり軸受であって、
前記内輪、外輪、及び保持器が導電性材料により構成され、かつ前記転動体が非導電性材料または難導電性材料により構成されているとともに、
前記保持器の内周側の一部または内輪の外周側の一部に、その保持器の偏芯に伴って前記内輪の外周面または保持器の内周面にそれぞれ接触する第１の通電部を設け、かつ前記保持器の外周側の一部または外輪の内周側の一部に、その保持器の偏芯に伴って前記外輪の内周面または保持器の外周面にそれぞれ接触する第２の通電部を設け、前記第１通電部と第２通電部の周方向位置を互いにずらしてこれらの第１及び第２の通電部により内外輪間を電気的に導通させることを特徴とするものである（請求項４）。
【００１０】
上記のように構成された転がり軸受（請求項４）では、内外輪及び保持器が導電性材料により構成され、上記第１の通電部が保持器の偏芯に伴って当該保持器と内輪との間を電気的に導通し、かつ上記第２の通電部が保持器の偏芯に伴って当該保持器と外輪との間を電気的に導通して内外輪間を電気的に導通させる。従って、転動体が鋼製の場合とほぼ同様な帯電防止効果が得られ、軸受の帯電を十分に抑制することができる。また、導電性材料によって保持器を構成していることから、合成樹脂からなる従来例と異なり、保持器自体の帯電を防止し、軸受の帯電量の増加を防ぐことができ、帯電による異物の吸着を抑えることができる。
【００１１】
【発明の実施の形態】
以下、本発明の転がり軸受の好ましい実施形態について、図面を参照しながら説明する。尚、以下の説明では、ＨＤＤ装置に適用した場合について説明する。図１は本発明の一実施形態による玉軸受を示す断面図であり、図２は図１のII−II線断面図である。但し、図２では、ボール４の図示は省略している。
図において、本実施形態の玉軸受１では、固定輪としての内輪２及び回転輪としての外輪３と、これらの内外輪の間に転動自在に配列した転動体としての複数のボール４と、ボール４をそれぞれ保持する複数のポケット５ａを備えた円環状の保持器５と、上記内外輪間の環状開口部をシールするシール板６とを備えている。上記内輪２及び外輪３は、例えばスピンドルモータのスピンドル軸１０及び磁気ディスクを一体回転可能に搭載したモータハブ（図示せず）にそれぞれ取り付けられており、モータによるディスク回転を円滑に支承する。尚、上記スピンドル軸１０及びモータハブは金属等の導電体であり、また、スピンドル軸１０は金属製のモータベース（図示せず）に軸支されており、このベースを介して接地されるようになっている。
【００１２】
上記内輪２及び外輪３は、軸受用鋼（例えば、ＳＵＪ２）等の導電性材料により構成されている。
上記ボール４は、非導電性材料、例えば窒化ケイ素系又はジルコニア系のセラミックス材料により構成されており、内外輪２，３間を電気的に絶縁した状態で、内輪２の外周面２ａに形成された軌道溝２ａ１及び外輪３の内周面３ａに形成された軌道溝３ａ１上を転走する。尚、この説明以外に、１０⁶Ω・ｃｍより大きい体積抵抗率（ＪＩＳ、Ｋ６９１１に記載）を有する難導電性材料により、ボール４を構成してもよい。
【００１３】
上記保持器５は、環状の基部５ｂと、この基部５ｂから周方向に沿って所定間隔に突設された複数の柱部５ｃと、これらの柱部５ｃの相互間に、上記ポケット５ａを配置した冠型の環状体であり、導電性材料により構成されている。この導電性材料は、ポリアミド樹脂やフッ素樹脂等の合成樹脂に、導電性を付与するための添加物を加えたものである。添加物は、カーボンファイバー等の導電性繊維、アルミニウム合金や銅等の金属粉末、あるいは黒鉛等の導電性無機粉末を用いる。保持器５は、導電性付与物を添加した合成樹脂を、射出成形法によって一体成形することにより形成されている。このように導電性付与物を含んだ合成樹脂を一体成形しているので、保持器５を高精度に形成することができる。
【００１４】
上記ポケット５ａは、ボール４との隙間を適切な値とした真円状の断面形状を有している（図２を参照）。つまり、ポケット５ａは、上記隙間を適切な値とすることにより、当該ポケット５ａ内でのボール詰まりを防止して軸受に回転不良が発生するのを防ぐとともに、ポケット５ａ内でのボール４の移動量を規制してボール４の周方向での不等配量が大きくなるのを防いで、回転非同期振れの発生、及び保持器音や振動が増大するのを防止している。尚、上記隙間は、ボール転走面に供給されるグリース等の潤滑剤溜めとしても機能しており、潤滑不良の発生を抑えるようになっている。
【００１５】
また、上記保持器５の基部５ｂには、図２に示すように、その基部内周を楕円形状に形成した第１の楕円形状部５ｄ（図２の内輪２側のクロスハッチ部にて図示）と、その基部外周を楕円形状に形成した第２の楕円形状部５ｅ（図２の外輪３側のクロスハッチ部にて図示）とが設けられている。これらの楕円形状部５ｄ，５ｅは、例えば周方向の全周にわたって、上記柱部５ｃの内周面５ｃ１及び外周面５ｃ２よりもそれぞれ径方向内方側及び径方向外方側に膨れ出るように形成されている。また、楕円形状部５ｄ，５ｅは、図２に示すように、互いに位相が異なるように形成されており、保持器５が例えば図２の矢印Ｗにて示す方向に偏芯したときに、楕円形状部５ｄ，５ｅは同時に内輪２の外周面２ａ及び外輪３の内周面３ａにそれぞれ接触するように構成されている。詳細には、楕円形状部５ｄには、保持器５の偏芯に伴って内輪２の外周面２ａに接触する第１の通電部としての短径部分５ｄ１（保持器内周面５ｃから最も径方向内方に膨れ出た部分）が設けられ、楕円形状部５ｅには、保持器５の偏芯に伴って外輪３の内周面３ａに接触する第２の通電部としての長径部分５ｅ１（保持器外周面５ｅから最も径方向外方に膨れ出た部分）が設けられている。これらの短径部分５ｄ１及び長径部分５ｅ１は、図２に示すように、互いに位相が９０゜異なるよう形成されており、例えば軸受回転時に、保持器５ががたつくことにより、上記短径部分５ｄ１が内輪２の外周面２ａの肩部に接触し、同時に上記長径部分５ｅ１が外輪３の内周面３ａの肩部に接触するようになっている。
【００１６】
以上のように構成された本実施形態の玉軸受１では、内外輪２，３及び保持器５を導電性材料により構成するとともに、内輪２の外周面２ａ及び外輪３の内周面３ａにそれぞれ接触可能な第１及び第２の楕円形状部５ｄ，５ｅを保持器５の内周側及び外周側に設けている。これらの楕円形状部５ｄ，５ｅの短径部分５ｄ１及び長径部分５ｅ１が対応する内輪外周面２ａ及び外輪内周面３ａに接触したときに、内輪２と外輪３とが保持器５を介して電気的に導通する。従って、ボール４が鋼製の場合とほぼ同様な帯電防止効果を得ることができ、軸受の帯電を十分に抑制することができる。また、導電性材料からなる保持器５を用いたことから、合成樹脂からなる従来例と異なり、保持器自体の帯電を防止でき、ひいては軸受の帯電量の増加を防ぐことができる。従って、塵埃などの異物を大気中から吸着するのを抑えることができ、異物による異音の発生を防いで、軸受の音響特性が低下するのを防止することができる。
【００１７】
さらに、本実施形態の玉軸受１を用いたＨＤＤ装置では、外輪３と共に回転する磁気ディスクの電荷を、当該軸受を介して逃がすことができることから、上記従来例と異なり、磁気ディスクに電荷が蓄積されるのを防ぐことができる。この結果、蓄積された電荷による、帯電した磁気ディスクとヘッドとが衝突するヘッドクラッシュ等の不具合を防止することができる。しかも、磁性流体シールや常時接触式の導電性部材等のアース手段を軸受やＨＤＤ装置に設ける必要がないので、軸受及びＨＤＤ装置の構成を簡素化することができる。また、常時接触式のアース手段を用いるよりも、回転トルクを小さくすることができるため、ＨＤＤ装置のような小型、高速回転の用途では特に好適である。
【００１８】
尚、上記の説明では、第１及び第２の通電部として、上記第１及び第２の楕円形状部５ｄ，５ｅの短径部分５ｄ１及び長径部分５ｅ１をそれぞれ用いた構成について説明したが、本発明はこれに限定されるものではなく、保持器５の内周側及び外周側に設けられ、保持器５の偏芯に伴って内輪２の外周面２ａ及び外輪３の内周面３ａにそれぞれ接触して内外輪２，３間を電気的に導通させるものであれば何等限定されない。
具体的には、図３に示すように、第１の通電部として、例えば基部５ｂの内周面から径方向内方側に突出した第１の突起部５ｆを、周方向に沿って例えば４箇所設け、第２の通電部として、基部５ｂの外周面から径方向外方側に突出した第２の突起部５ｇを、周方向に沿って例えば４箇所設ける構成でもよい。このように構成した場合、保持器５が例えば同図の矢印Ｗにて示す方向に偏芯したときに、同図右下の突起部５ｆが内輪外周面２ａに接触し、同時に、同図左上の突起部５ｇが外輪内周面３ａに接触することにより、内外輪２，３間は電気的に導通される。尚、これらの突起部５ｆ，５ｇは、それぞれ内輪外周面２ａ及び外輪内周面３ａに接触するように、保持器５の内周面及び外周面から径方向内方側及び径方向外方側に突出したものであればよく、柱部５ｃの内周面５ｃ１及び外周面５ｃ２に設けてもよい。
【００１９】
また、上記の説明では、保持器５の内周側及び外周側に第１及び第２の通電部をそれぞれ設けた構成について説明したが、本発明はこれに限定されるものではなく、保持器５の内周側または内輪２の外周側に、その保持器５の偏芯に伴って内輪２の外周面２ａまたは保持器５の内周面にそれぞれ接触する第１の通電部を設け、かつ保持器５の外周側または外輪３の内周側に、その保持器５の偏芯に伴って外輪３の内周面３ａまたは保持器５の外周面にそれぞれ接触する第２の通電部を設け、これらの第１及び第２の通電部により内外輪２，３間を電気的に導通させるものであればよい。具体的には、内輪２の外周面２ａから径方向外方側に突出した突起部を第１の通電部として内輪２の外周側に設け、かつ外輪３の内周面３ａから径方向内方側に突出した突起部を第２の通電部として外輪３の内周側に設けて、保持器５の偏芯に伴って各突起部を同時に保持器５の対応する内周面及び外周面に接触させて、保持器５と内輪２との間及び保持器５と外輪３との間を電気的にそれぞれ導通して内外輪２，３間を電気的に導通させる構成でもよい。さらに、第１及び第２の通電部の一方を保持器５に設け、他方を内輪２または外輪３に設けてもよい。
【００２０】
また、上記の説明では、転動体としてのボール４を備えた玉軸受１をＨＤＤ装置に適用した場合について説明したが、本発明の転がり軸受は導電性材料からなる内外輪及び保持器と非導電性材料または難導電性材料からなる転動体とを備え、内外輪及び保持器のうち少なくとも保持器に設けた上記第１及び第２の通電部により内外輪間を電気的に導通させるものであれば、転動体の形状等には何等限定されない。さらに、本発明は固定体に対して回転体を回転させるものであれば、その固定体と回転体との間の所定部に取り付けられて、回転体を回転自在に支持する軸受として好適に使用することができる。
また、上記の説明では、導電性を有する保持器５として、導電性付与物を添加した合成樹脂を射出成形したものを用いた場合について説明したが、導電性金属を打抜加工したものや削り出したもの等を保持器５として用いることもできる。
【００２１】
【発明の効果】
以上のように構成された本発明は以下の効果を奏する。
請求項１の転がり軸受によれば、上記第１及び第２の通電部が内輪の外周面及び外輪の内周面にそれぞれ接触したときに、内輪と外輪とが保持器を介して電気的に導通するので、転動体が鋼製の場合とほぼ同様な帯電防止効果が得られ、軸受の帯電を十分に抑制することができる。また、保持器が導電性材料により構成されているので、合成樹脂からなる従来例と異なり、保持器自体の帯電を防止して軸受の帯電量の増加を防ぐことができ、帯電による異物の吸着を抑えることができる。この結果、異物による異音の発生を防いで、軸受の音響特性が低下するのを防止することができる。しかも、軸受が組み込まれた装置において、回転輪と共に回転する装置側の回転体の電荷を、当該軸受を介して逃がすことができるので、上記ヘッドクラッシュ等の不具合を防止することができるとともに、磁性流体シールなどのアース手段を軸受や装置に設ける必要がないので、軸受及び装置構成を簡素化することができる。
【００２２】
また、請求項２または請求項３の転がり軸受によれば、それぞれ上記短径部分及び長径部分または各突起部が対応する内輪外周面及び外輪内周面に接触したときに、その内輪と外輪とが保持器を介して電気的に導通するので、当該軸受の帯電を簡単な構成で十分に抑制することができ、よって帯電に起因する軸受性能の低下などを防ぐことができる。
【００２３】
また、請求項４の転がり軸受によれば、第１及び第２の通電部が保持器の偏芯に伴って保持器と内輪との間及び保持器と外輪との間を電気的にそれぞれ導通して内外輪間を電気的に導通させるので、転動体が鋼製の場合とほぼ同様な帯電防止効果が得られ、軸受の帯電を十分に抑制することができる。また、導電性材料によって保持器を構成していることから、合成樹脂からなる従来例と異なり、保持器自体の帯電を防止し、軸受の帯電量の増加を防ぐことができ、帯電による異物の吸着を抑えることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態による玉軸受を示す断面図である。
【図２】図１のII−II線断面図である。
【図３】図１におけるII−II線断面に相当する、別の実施形態の玉軸受を示す断面図である。
【符号の説明】
１玉軸受
２内輪
３外輪
４ボール
５保持器
５ａポケット
５ｂ基部
５ｃ柱部
５ｄ１短径部分（第１の通電部）
５ｅ１長径部分（第２の通電部）
５ｇ第１の突起部（第１の通電部）
５ｈ第２の突起部（第２の通電部）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling bearing that is used in a magnetic recording device such as a hard disk drive (HDD) device and supports a rotating body such as a disk medium.
[0002]
[Prior art and problems to be solved by the invention]
For example, in rolling bearings used in HDD devices, rolling elements made of a ceramic material that excel in rotation / acoustic performance, fretting resistance, wear resistance, etc. in order to support high-speed rotation of a magnetic disk by a spindle motor or the like with high precision. May be used. This ceramic material is generally a non-conductive material such as silicon nitride or zirconia, that is, an insulating material. Therefore, the inner and outer rings of this conventional rolling bearing are electrically insulated. Therefore, when this conventional rolling bearing is used in an HDD device, the electric charge on the magnetic disk rotating together with the outer ring (rotating ring) is accumulated without any escape. As a result, there is a possibility of causing problems such as a head crash that the head is electrically attracted to and contacts the charged magnetic disk. In order to prevent such a head crash and the like, it has been proposed to attach a magnetic fluid seal as a grounding means to a bearing or device to release the charged electric charge, but the magnetic fluid seal alone may not be sufficient for preventing charging. In addition, the bearings and device configuration became complicated.
In addition, a ceramic material to which a certain level of conductivity is imparted by adding a conductive material has also been proposed, but it is difficult to achieve both sufficient conductivity and strength such as fretting resistance and wear resistance. In the case of priority, even if it is not an insulating material, it is a poorly conductive material and does not solve the problems such as the head crash. Here, it is assumed that the hardly conductive material has a volume resistivity (described in JIS, K6911) larger than 10 ⁶ Ω · cm.
[0003]
Further, in the conventional rolling bearing as described above, a cage made of synthetic resin such as polyamide resin has been used in recent years. However, since this synthetic resin itself is a material that is easily charged, the charge amount of the cage and, consequently, the charge amount of the bearing is increased. As a result, the bearing is likely to adsorb foreign matter such as dust in the atmosphere due to the charged electric charge, and abnormal noise (dust noise) is generated during rotation of the bearing, and the acoustic characteristics thereof may be remarkably deteriorated.
[0004]
In view of the conventional problems as described above, the present invention can sufficiently suppress the charging of a rolling bearing provided with a rolling element made of a non-conductive material or a hardly conductive material. An object of the present invention is to provide a rolling bearing capable of preventing a decrease in bearing performance due to the above.
[0005]
[Means for Solving the Problems]
The rolling bearing according to the present invention includes an inner ring and an outer ring, a plurality of rolling elements provided so as to be able to roll between the inner ring and the outer ring, and a circle that holds the plurality of rolling elements at predetermined intervals along a circumferential direction. A rolling bearing with an annular cage,
The inner ring, the outer ring, and the cage are made of a conductive material, and the rolling element is made of a non-conductive material or a hardly conductive material,
The inner and outer rings are electrically connected to a part of the inner peripheral side and a part of the outer peripheral side of the cage by contacting the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring with the eccentricity of the cage. The first and second energization portions that are electrically connected to each other are provided , and the circumferential positions of the first energization portion and the second energization portion are shifted from each other (Claim 1).
[0006]
In the rolling bearing configured as described above, the inner and outer rings and the cage are made of a conductive material, and the first and second current-carrying portions provided in the cage are aligned with the eccentricity of the cage. When the outer peripheral surface and the inner peripheral surface of the outer ring come into contact with each other, the inner and outer rings are electrically connected through the cage. Accordingly, the same antistatic effect as that obtained when the rolling element is made of steel can be obtained, and the charging of the bearing can be sufficiently suppressed. In addition, since the cage is made of a conductive material, unlike the conventional example made of a synthetic resin, the cage itself can be prevented from being charged and the bearing charge can be prevented from increasing. Adsorption can be suppressed.
[0007]
Further, in the rolling bearing (Claim 1), the retainer includes an annular base portion, a plurality of column portions projecting from the base portion in a circumferential direction at a predetermined interval, and the column portions. Provided with a plurality of pockets respectively holding the plurality of rolling elements,
The inner periphery and the outer periphery of the base are formed in an elliptical shape with different phases, the short diameter part of the elliptical shape of the inner periphery of the base is configured as the first current-carrying portion, and the elliptical shape of the outer periphery of the base The long diameter portion may be configured as the second energization portion (claim 2).
In this case, the short diameter portion and the long diameter portion are in contact with the inner ring outer peripheral surface and the outer ring inner peripheral surface, respectively, thereby electrically connecting the inner and outer rings through the cage.
[0008]
In the rolling bearing (Claim 1), the first current-carrying portion is constituted by a first protrusion protruding radially inward from the inner peripheral surface of the cage, and the second An energization part may be constituted by the 2nd projection part projected to the diameter direction outside from the peripheral face of the above-mentioned maintenance machine (claim 3).
In this case, the projections contact the corresponding inner ring outer peripheral surface and outer ring inner peripheral surface to electrically connect the inner and outer rings via the cage.
[0009]
The rolling bearing according to the present invention includes an inner ring and an outer ring, a plurality of rolling elements provided between the inner ring and the outer ring so as to be freely rollable, and the plurality of rolling elements held at predetermined intervals along a circumferential direction. A rolling bearing provided with an annular retainer,
The inner ring, the outer ring, and the cage are made of a conductive material, and the rolling element is made of a non-conductive material or a hardly conductive material,
A first energization section that contacts a part of the inner ring side of the cage or a part of the outer ring side of the inner ring with the outer circumferential surface of the inner ring or the inner circumferential surface of the cage in accordance with the eccentricity of the cage. And a part on the outer peripheral side of the retainer or a part on the inner peripheral side of the outer ring, which comes into contact with the inner peripheral surface of the outer ring or the outer peripheral surface of the retainer in accordance with the eccentricity of the retainer. Two energization parts are provided, and the circumferential positions of the first energization part and the second energization part are shifted from each other, and the first and second energization parts electrically connect the inner and outer rings. (Claim 4).
[0010]
In the rolling bearing configured as described above (Claim 4), the inner and outer rings and the cage are made of a conductive material, and the first energizing portion is formed by the cage and the inner ring along with the eccentricity of the cage. The second current-carrying portion is electrically connected between the retainer and the outer ring and is electrically connected between the inner and outer rings with the eccentricity of the retainer. Accordingly, the same antistatic effect as that obtained when the rolling element is made of steel can be obtained, and the charging of the bearing can be sufficiently suppressed. In addition, since the cage is made of a conductive material, unlike the conventional example made of a synthetic resin, the cage itself can be prevented from being charged and the bearing charge can be prevented from increasing. Adsorption can be suppressed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the rolling bearing of the present invention will be described with reference to the drawings. In the following description, a case where the present invention is applied to an HDD device will be described. FIG. 1 is a sectional view showing a ball bearing according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. However, the illustration of the ball 4 is omitted in FIG.
In the drawing, in the ball bearing 1 of the present embodiment, an inner ring 2 as a fixed ring and an outer ring 3 as a rotating ring, and a plurality of balls 4 as rolling elements arranged so as to roll between these inner and outer rings, An annular cage 5 having a plurality of pockets 5a for holding the balls 4 and a seal plate 6 for sealing an annular opening between the inner and outer rings are provided. The inner ring 2 and the outer ring 3 are respectively attached to, for example, a motor hub (not shown) on which a spindle shaft 10 of a spindle motor and a magnetic disk are mounted so as to be integrally rotatable, and smoothly support disk rotation by the motor. The spindle shaft 10 and the motor hub are made of a conductor such as metal, and the spindle shaft 10 is pivotally supported by a metal motor base (not shown) so that it is grounded via this base. It has become.
[0012]
The inner ring 2 and the outer ring 3 are made of a conductive material such as bearing steel (for example, SUJ2).
The ball 4 is made of a non-conductive material, for example, a silicon nitride-based or zirconia-based ceramic material, and is formed on the outer peripheral surface 2a of the inner ring 2 in a state where the inner and outer rings 2, 3 are electrically insulated. Rolling on the raceway groove 2a1 and the raceway groove 3a1 formed in the inner peripheral surface 3a of the outer ring 3. In addition to this description, the ball 4 may be made of a hardly conductive material having a volume resistivity (described in JIS, K6911) greater than 10 ⁶ Ω · cm.
[0013]
The retainer 5 includes an annular base 5b, a plurality of pillars 5c projecting from the base 5b in the circumferential direction at a predetermined interval, and the pockets 5a disposed between the pillars 5c. The crown-shaped annular body is made of a conductive material. This conductive material is obtained by adding an additive for imparting conductivity to a synthetic resin such as a polyamide resin or a fluororesin. As the additive, conductive fiber such as carbon fiber, metal powder such as aluminum alloy or copper, or conductive inorganic powder such as graphite is used. The cage 5 is formed by integrally molding a synthetic resin to which a conductivity imparting substance is added by an injection molding method. Since the synthetic resin containing the conductivity imparting substance is integrally formed in this way, the cage 5 can be formed with high accuracy.
[0014]
The pocket 5a has a perfect circular cross-sectional shape with an appropriate value for the gap with the ball 4 (see FIG. 2). That is, the pocket 5a sets the above clearance to an appropriate value, thereby preventing the balls from being clogged in the pocket 5a and preventing the rotation failure of the bearing, and the movement of the balls 4 in the pocket 5a. The amount is regulated to prevent the uneven distribution of the balls 4 in the circumferential direction from increasing, thereby preventing the occurrence of rotational asynchronous vibration and the increase in cage noise and vibration. The gap functions also as a reservoir for a lubricant such as grease supplied to the ball rolling surface, and suppresses the occurrence of poor lubrication.
[0015]
As shown in FIG. 2, the base 5b of the retainer 5 has a first elliptical part 5d (illustrated as a cross hatch part on the inner ring 2 side in FIG. 2) having an inner periphery of the base formed in an elliptical shape. ) And a second elliptical portion 5e (illustrated in the cross hatch portion on the outer ring 3 side in FIG. 2) having an elliptical outer periphery. These oval-shaped portions 5d and 5e are, for example, swelled radially inward and radially outward from the inner peripheral surface 5c1 and outer peripheral surface 5c2 of the column portion 5c, respectively, over the entire circumference in the circumferential direction. Is formed. Further, as shown in FIG. 2, the elliptical portions 5d and 5e are formed so that the phases are different from each other. When the cage 5 is eccentric in the direction indicated by the arrow W in FIG. The shape parts 5d and 5e are configured to simultaneously contact the outer peripheral surface 2a of the inner ring 2 and the inner peripheral surface 3a of the outer ring 3, respectively. Specifically, the elliptical portion 5d has a short-diameter portion 5d1 as the first current-carrying portion that comes into contact with the outer peripheral surface 2a of the inner ring 2 along with the eccentricity of the cage 5 (the largest diameter from the cage inner peripheral surface 5c). A portion bulging inward in the direction) is provided, and the elliptical portion 5e is provided with a long diameter portion 5e1 (second energization portion that comes into contact with the inner peripheral surface 3a of the outer ring 3 with the eccentricity of the cage 5). The portion swelled outwardly in the radial direction from the outer peripheral surface 5e of the cage is provided. As shown in FIG. 2, the short diameter portion 5d1 and the long diameter portion 5e1 are formed so that their phases are different from each other by 90 °. For example, when the bearing 5 is shaken during rotation of the bearing, the short diameter portion 5d1 The long diameter portion 5 e 1 is in contact with the shoulder portion of the inner peripheral surface 3 a of the outer ring 3 while contacting the shoulder portion of the outer peripheral surface 2 a of the inner ring 2.
[0016]
In the ball bearing 1 of the present embodiment configured as described above, the inner and outer rings 2 and 3 and the cage 5 are made of a conductive material, and the outer peripheral surface 2a of the inner ring 2 and the inner peripheral surface 3a of the outer ring 3 are respectively provided. The first and second elliptical portions 5d and 5e that can be contacted are provided on the inner peripheral side and the outer peripheral side of the cage 5. When the short-diameter portion 5d1 and the long-diameter portion 5e1 of the elliptical portions 5d and 5e come into contact with the corresponding inner ring outer peripheral surface 2a and outer ring inner peripheral surface 3a, the inner ring 2 and the outer ring 3 are electrically connected via the cage 5. Conductive. Therefore, it is possible to obtain the same antistatic effect as when the ball 4 is made of steel, and to sufficiently suppress the charging of the bearing. In addition, since the cage 5 made of a conductive material is used, unlike the conventional example made of a synthetic resin, the cage itself can be prevented from being charged, and consequently the increase in the charge amount of the bearing can be prevented. Accordingly, it is possible to suppress the adsorption of foreign matters such as dust from the atmosphere, and it is possible to prevent the generation of noise due to the foreign matters and to prevent the acoustic characteristics of the bearing from deteriorating.
[0017]
Further, in the HDD device using the ball bearing 1 of the present embodiment, since the electric charge of the magnetic disk rotating together with the outer ring 3 can be released through the bearing, the electric charge is accumulated in the magnetic disk unlike the conventional example. Can be prevented. As a result, it is possible to prevent problems such as a head crash caused by collision between the charged magnetic disk and the head due to the accumulated charge. In addition, since it is not necessary to provide a grounding means such as a magnetic fluid seal or a constant contact type conductive member in the bearing or the HDD device, the configuration of the bearing and the HDD device can be simplified. In addition, since the rotational torque can be reduced as compared with the use of the always-contact type grounding means, it is particularly suitable for small-sized and high-speed rotation applications such as HDD devices.
[0018]
In the above description, the configuration using the short diameter portion 5d1 and the long diameter portion 5e1 of the first and second oval-shaped portions 5d and 5e as the first and second energization portions has been described. The present invention is not limited to this, and is provided on the inner peripheral side and the outer peripheral side of the cage 5, and is respectively provided on the outer peripheral surface 2 a of the inner ring 2 and the inner peripheral surface 3 a of the outer ring 3 along with the eccentricity of the cage 5. There is no limitation as long as it is in electrical contact between the inner and outer rings 2 and 3 by contact.
Specifically, as shown in FIG. 3, as the first energization portion, for example, a first protrusion 5f protruding radially inward from the inner peripheral surface of the base portion 5b is provided, for example, 4 along the circumferential direction. For example, four second projecting portions 5g that protrude radially outward from the outer peripheral surface of the base portion 5b may be provided as the second energizing portion along the circumferential direction. In this case, when the cage 5 is eccentric in the direction indicated by the arrow W in the figure, for example, the lower right protrusion 5f contacts the inner ring outer peripheral surface 2a, and at the same time, the upper left in the figure. When the protruding portion 5g contacts the inner peripheral surface 3a of the outer ring, the inner and outer rings 2 and 3 are electrically connected. These protrusions 5f and 5g are radially inward and radially outward from the inner and outer peripheral surfaces of the cage 5 so as to contact the inner ring outer peripheral surface 2a and the outer ring inner peripheral surface 3a, respectively. And may be provided on the inner peripheral surface 5c1 and the outer peripheral surface 5c2 of the column portion 5c.
[0019]
In the above description, the configuration in which the first and second energization portions are provided on the inner peripheral side and the outer peripheral side of the cage 5 has been described. However, the present invention is not limited thereto, and the cage is not limited thereto. A first current-carrying portion that contacts the outer peripheral surface 2a of the inner ring 2 or the inner peripheral surface of the retainer 5 with the eccentricity of the retainer 5 on the inner peripheral side of the inner ring 5 or the outer peripheral side of the inner ring 2, and On the outer peripheral side of the cage 5 or the inner peripheral side of the outer ring 3, there are provided second current-carrying portions that respectively contact the inner peripheral surface 3 a of the outer ring 3 or the outer peripheral surface of the cage 5 with the eccentricity of the cage 5. As long as the first and second current-carrying portions electrically connect the inner and outer rings 2 and 3. Specifically, a protrusion projecting radially outward from the outer peripheral surface 2 a of the inner ring 2 is provided on the outer peripheral side of the inner ring 2 as a first energizing portion, and radially inward from the inner peripheral surface 3 a of the outer ring 3. Protrusions protruding sideways are provided on the inner peripheral side of the outer ring 3 as second energization parts, and each protrusion is simultaneously provided on the corresponding inner peripheral surface and outer peripheral surface of the cage 5 as the cage 5 is eccentric. It may be configured to electrically connect between the cage 5 and the inner ring 2 and between the cage 5 and the outer ring 3 to electrically connect the inner and outer rings 2 and 3. Further, one of the first and second energization parts may be provided in the cage 5 and the other may be provided in the inner ring 2 or the outer ring 3.
[0020]
In the above description, the case where the ball bearing 1 including the balls 4 as rolling elements is applied to the HDD device has been described. However, the rolling bearing of the present invention is not electrically conductive with inner and outer rings and cages made of a conductive material. A rolling element made of a conductive material or a hardly conductive material, and at least one of the inner and outer rings and the cage is electrically connected between the inner and outer rings by the first and second current-carrying portions provided in the cage. For example, the shape of the rolling element is not limited at all. Furthermore, if this invention rotates a rotary body with respect to a fixed body, it is suitably used as a bearing which is attached to the predetermined part between the fixed body and a rotary body, and supports a rotary body rotatably. can do.
Further, in the above description, the case has been described where the conductive cage 5 is made by injection-molding a synthetic resin to which a conductivity imparting substance is added. However, the conductive metal is punched or shaved. What was taken out can also be used as the cage 5.
[0021]
【The invention's effect】
The present invention configured as described above has the following effects.
According to the rolling bearing of claim 1, the inner ring and the outer ring are electrically connected via the cage when the first and second current-carrying portions come into contact with the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, respectively. Since it conducts, an antistatic effect similar to that when the rolling elements are made of steel can be obtained, and the charging of the bearing can be sufficiently suppressed. In addition, since the cage is made of a conductive material, unlike the conventional example made of synthetic resin, the cage itself can be prevented from being charged to prevent an increase in the amount of charge on the bearing. Can be suppressed. As a result, it is possible to prevent the generation of abnormal noise due to foreign matter and prevent the acoustic characteristics of the bearing from deteriorating. In addition, in a device in which a bearing is incorporated, the charge on the rotating body on the device side that rotates together with the rotating wheel can be released through the bearing, so that problems such as head crashes can be prevented and magnetic properties can be prevented. Since there is no need to provide a grounding means such as a fluid seal in the bearing or device, the configuration of the bearing and device can be simplified.
[0022]
Further, according to the rolling bearing of claim 2 or claim 3, when the short diameter portion and the long diameter portion or the projections contact the corresponding inner ring outer peripheral surface and outer ring inner peripheral surface, respectively, the inner ring and the outer ring Is electrically conducted through the cage, so that the charging of the bearing can be sufficiently suppressed with a simple configuration, and hence the deterioration of the bearing performance due to the charging can be prevented.
[0023]
According to the rolling bearing of claim 4, the first and second current-carrying portions are electrically connected between the cage and the inner ring and between the cage and the outer ring in accordance with the eccentricity of the cage. Thus, since the inner and outer rings are electrically connected to each other, the same antistatic effect as that obtained when the rolling elements are made of steel can be obtained, and the charging of the bearing can be sufficiently suppressed. In addition, since the cage is made of a conductive material, unlike the conventional example made of a synthetic resin, the cage itself can be prevented from being charged and the bearing charge can be prevented from increasing. Adsorption can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a ball bearing according to an embodiment of the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a cross-sectional view showing a ball bearing of another embodiment corresponding to a cross section taken along line II-II in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ball bearing 2 Inner ring 3 Outer ring 4 Ball 5 Cage 5a Pocket 5b Base part 5c Column part 5d1 Short diameter part (1st electricity supply part)
5e1 Long diameter part (second energization part)
5g 1st protrusion (1st electricity supply part)
5h 2nd protrusion (2nd electricity supply part)

Claims

An inner ring and an outer ring; a plurality of rolling elements provided between the inner ring and the outer ring so as to be freely rollable; and an annular cage for holding the plurality of rolling elements at a predetermined interval along a circumferential direction. Rolling bearings,
The inner ring, the outer ring, and the cage are made of a conductive material, and the rolling element is made of a non-conductive material or a hardly conductive material,
The inner and outer rings are electrically connected to a part of the inner peripheral side and a part of the outer peripheral side of the cage by contacting the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring with the eccentricity of the cage. A rolling bearing characterized in that first and second current-carrying parts that are electrically connected to each other are provided , and circumferential positions of the first and second current-carrying parts are shifted from each other .

The retainer is provided between the annular base, a plurality of pillars protruding from the base at a predetermined interval along the circumferential direction, and holds the plurality of rolling elements. With multiple pockets,
While forming the inner circumference and the outer circumference of the base into an elliptical shape with different phases,
The short-diameter portion in the elliptical shape of the inner periphery of the base is configured as the first energizing portion, and the long-diameter portion of the elliptical shape in the outer periphery of the base is configured as the second energizing portion. The rolling bearing according to Item 1.

The first current-carrying portion is configured by a first protrusion that protrudes radially inward from the inner circumferential surface of the cage, and the second current-carrying portion has a diameter from the outer circumferential surface of the cage. The rolling bearing according to claim 1, wherein the rolling bearing is configured by a second protrusion protruding outward in the direction.

An inner ring and an outer ring; a plurality of rolling elements provided between the inner ring and the outer ring so as to be freely rollable; and an annular cage for holding the plurality of rolling elements at a predetermined interval along a circumferential direction. Rolling bearings,
The inner ring, the outer ring, and the cage are made of a conductive material, and the rolling element is made of a non-conductive material or a hardly conductive material,
A first energization section that contacts a part of the inner ring side of the cage or a part of the outer ring side of the inner ring with the outer circumferential surface of the inner ring or the inner circumferential surface of the cage in accordance with the eccentricity of the cage. And a part on the outer peripheral side of the retainer or a part on the inner peripheral side of the outer ring, which comes into contact with the inner peripheral surface of the outer ring or the outer peripheral surface of the retainer in accordance with the eccentricity of the retainer. Two energization parts are provided, and the circumferential positions of the first energization part and the second energization part are shifted from each other, and the first and second energization parts electrically connect the inner and outer rings. Rolling bearing.