JP2004176815A

JP2004176815A - Liquid bearing device

Info

Publication number: JP2004176815A
Application number: JP2002343826A
Authority: JP
Inventors: Isao Komori; 功古森; Toshihiko Tanaka; 敏彦田中
Original assignee: NTN Corp; NTN Toyo Bearing Co Ltd
Current assignee: NTN Corp
Priority date: 2002-11-27
Filing date: 2002-11-27
Publication date: 2004-06-24

Abstract

<P>PROBLEM TO BE SOLVED: To simplify assembling process of a liquid bearing device that supports, in a non-contact manner, a rotating member with a film of lubricating oil formed in clearances on radial bearings. <P>SOLUTION: A sealing member 4 comprises a base part 4a, and a leg part 4b integrally extending from the base part 4a downward in the axial direction. The base part 4a has an inner circumferential surface 4a1 forming a sealing space S1 between the surface 4a1 and the outer circumferential surface 2a of a shaft member 2. The leg part 4b has an inner circumferential surface 4b1 being larger than the inner circumferential surface 4a1 of the base part 4a in diameter and forming an oil retaining space S2 between the surface 4b1 and the outer circumferential surface 2a of the shaft member 2, and an abutting surface 4b2 abutting on the upper end surface 8c of a bearing sleeve 8. The bearing sleeve 8 is sandwiched between an abutting surface 7d1 at a stepped part 7d in the housing 7 and the abutting surface 4b2 of the leg part 4b of the seal member 4 in the axial direction, and is fixed in the housing 7. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ラジアル軸受隙間に生じる潤滑油の油膜によって回転部材を非接触支持する流体軸受装置に関する。この軸受装置は、情報機器、例えばＨＤＤ、ＦＤＤ等の磁気ディスク装置、ＣＤ−ＲＯＭ、ＣＤ−Ｒ／ＲＷ、ＤＶＤ−ＲＯＭ／ＲＡＭ等の光ディスク装置、ＭＤ、ＭＯ等の光磁気ディスク装置などのスピンドルモータ、レーザビームプリンタ（ＬＢＰ）のポリゴンスキャナモータ、あるいは電気機器、例えば軸流ファンなどの小型モータ用として好適である。
【０００２】
【従来の技術】
上記各種モータには、高回転精度の他、高速化、低コスト化、低騒音化などが求められている。これらの要求性能を決定づける構成要素の一つに当該モータのスピンドルを支持する軸受があり、近年では、上記要求性能に優れた特性を有する流体軸受の使用が検討され、あるいは実際に使用されている。
【０００３】
この種の流体軸受は、軸受隙間内の潤滑油に動圧を発生させる動圧発生手段を備えたいわゆる動圧軸受と、動圧発生手段を備えていないいわゆる真円軸受（軸受面が真円形状である軸受）とに大別される。
【０００４】
例えば、ＨＤＤ等のディスク駆動装置のスピンドルモータやレーザビームプリンタ（ＬＢＰ）のポリゴンスキャナモータに組込まれる流体軸受装置では、軸部材をラジアル方向に回転自在に非接触支持するラジアル軸受部と、軸部材をスラスト方向に回転自在に支持するスラスト軸受部とが設けられ、ラジアル軸受部として、軸受スリーブの内周面又は軸部材の外周面に動圧発生用の溝（動圧溝）を設けた動圧軸受が用いられる。スラスト軸受部としては、例えば、軸部材の一端側端面をスラスト部材によって支持する構造の軸受（いわゆるピボット軸受）が用いられる。通常、軸受スリーブはハウジングの内周の所定位置に固定され、また、ハウジングの内部空間の潤滑油が外部に漏れるのを防止するため、ハウジングの開口部にシール部材を配設する場合が多い（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特開２００１―１２４０５７号公報
【０００６】
また、シール部材と軸受スリーブの端面との間に一定の間隔を設け、該間隔部を油の保持空間とした流体軸受装置もある（例えば、特許文献２参照）。
【０００７】
【特許文献１】
特開２００１―１２４０５７号公報
【特許文献２】
特開平１１−１０８０５３号公報
【０００８】
【発明が解決しようとする課題】
上記構成の流体軸受装置は、ハウジング、軸受スリーブ、軸部材、スラスト部材、及びシール部材といった部品で構成され、情報機器の益々の高性能化に伴って必要とされる高い軸受性能を確保すべく、各部品の加工精度や組立精度を高める努力がなされている。その一方で、情報機器の低価格化の傾向に伴い、この種の流体軸受装置に対するコスト低減の要求も益々厳しくなっている。
【０００９】
上記構成の流体軸受装置では、通常、軸受スリーブをハウジングの内周に接着剤又は圧入によって固定するが、前者の場合、接着剤の塗布、両部品の保持、接着剤の乾燥固化といった複数工程が必要であり、また、接着剤が固化するまでに比較的長い時間を要する。後者の場合、圧入時のしめしろによっては、軸受スリーブの内周面が内径側に変位して軸受隙間に変動をきたす可能性がある。
【００１０】
また、シール部材と軸受スリーブの端面との間に一定の間隔を設けた流体軸受装置では、ハウジングに対するシール部材と軸受スリーブの固定位置によって上記間隔部の軸方向寸法が変動し、上記間隔部を一定寸法に管理するのが難しい。
【００１１】
本発明の課題は、組立工程が簡素で、より一層低コストで、かつ信頼性の高い流体軸受装置を提供することである。
【００１２】
【課題を解決するための手段】
上記課題を解決するため、本発明は、ハウジングと、ハウジングの内部に固定された軸受スリーブと、軸受スリーブの内周面に挿入された軸部材と、軸受スリーブの内周面と軸部材の外周面との間に設けられ、軸受隙間に生じる潤滑油の油膜で軸部材をラジアル方向に支持するラジアル軸受部と、ハウジングの一端側に設けられ、軸部材をスラスト方向に支持するスラスト軸受部と、ハウジングの他端側に設けられ、ハウジングの内部をシールするシール部とを備えた流体軸受装置において、軸受スリーブを、ハウジングの一端側に設けた当接部とシール部とで軸方向の両側から挟持して、ハウジングの内部に固定した構成を提供する。
【００１３】
上記構成によれば、軸受スリーブをハウジングに接着剤で固定する場合に比べて、組立工程の工数及び時間を削減することができ、また、軸受スリーブをハウジングに圧入する場合に比べて、軸受隙間の変動がなく、安定した軸受機能を確保することができる。
【００１４】
上記構成において、上記の当接部は、ハウジングに一体に設け、あるは、ハウジングの一端部に固定されたスラスト部材に設けることができる。
【００１５】
また、本発明は、上記課題を解決するため、ハウジングと、ハウジングの内部に固定された軸受スリーブと、軸受スリーブの内周面に挿入された軸部材と、軸受スリーブの内周面と軸部材の外周面との間に設けられ、軸受隙間に生じる潤滑油の油膜で軸部材をラジアル方向に支持するラジアル軸受部と、ハウジングの一端側に設けられ、軸部材をスラスト方向に支持するスラスト軸受部と、ハウジングの他端側に設けられ、ハウジングの内部をシールするシール部とを備えた流体軸受装置において、シール部は、基部と、基部から一端側に延びた脚部とを備え、基部は、軸部材の外周面との間にシール空間を形成する内周面を有し、脚部は、基部の内周面よりも大径で、軸部材の外周面との間に保油空間を形成する内周面と、軸受スリーブの一端側端面と当接する当接面とを有する構成を提供する。
【００１６】
シール部の脚部の当接面と軸受スリーブの一端側端面とを当接させると、両者の相互間の軸方向位置関係が決まる。そして、シール部の脚部の内周面と軸部材の外周面との間に保油空間が形成され、この保油空間の空間容積は脚部の内周面の内径寸法と軸方向寸法とによって決まる。したがって、脚部の内周面の寸法を管理することによって、脚部の当接面と軸受スリーブの一端側端面とを当接させるだけで、所定の空間容積をもった保油空間を簡易に精度良く形成することができる。
【００１７】
特に、ハウジングの内部空間に潤滑流体を充満させる流体軸受装置では、上記保油空間を設けることにより、ハウジング内部における潤滑流体の保油量を多くして、潤滑流体の劣化を抑制し、軸受機能の長期安定化を図ることができる。また、上記保油空間を所定の空間容積に精度良く形成することができるので、ハウジングの内部空間に充満させる潤滑流体の総量管理も精度良く行うことができる。
【００１８】
上記のシール部は、ハウジングに一体形成することができ、あるいは、ハウジングの一端側に固定したシール部材によって構成することができる。後者の場合、シール部の基部と脚部は別体のリング部材によって構成することもできるが、部品点数を少なくする点から、基部と脚部は一体構成とするのが好ましい。また、シール部の少なくとも基部の内周面は撥油性を有することが好ましい。
【００１９】
また、上記構成において、軸受スリーブを、ハウジングの一端側に設けた当接部とシール部の脚部の当接面とで軸方向の両側から挟持して、ハウジングの内部に固定した構成とすることができる。
【００２０】
以上の構成において、ラジアル軸受部は軸受隙間内に潤滑油の動圧を発生させる動圧軸受とすることができる。
【００２１】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００２２】
図１は、第１の実施形態に係る流体軸受装置（流体動圧軸受装置）１を示している。この流体軸受装置１は、例えば、ＨＤＤ等のディスク駆動装置のスピンドルモータやレーザビームプリンタ（ＬＢＰ）のポリゴンスキャナモータに組込まれるもので、ハウジング７と、軸受スリーブ８と、軸部材２と、スラスト部材３と、シール部材４とを構成部品して構成される。
【００２３】
軸受スリーブ８の内周面８ａと軸部材２の外周面２ａとの間に第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２とが軸方向に離隔して設けられる。また、軸部材２の下側端面２ｂとハウジング７の底部７ｃに配設されたスラスト部材３との間にスラスト軸受部Ｔが設けられる。尚、説明の便宜上、スラスト軸受部Ｔの側を下側、スラスト軸受部Ｔと反対の側を上側として説明を進める。
【００２４】
軸受スリーブ８は、例えば、焼結金属からなる多孔質体、特に銅を主成分とする燒結金属の多孔質体で円筒状に形成される。この焼結金属で形成された軸受スリーブ８の内周面８ａには、第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２のラジアル軸受面となる上下２つの領域が軸方向に離隔して設けられ、該２つの領域には、例えばヘリングボーン形状の動圧溝８ａ１、８ａ２がそれぞれ形成される。尚、動圧溝の形状として、スパイラル形状や軸方向溝形状等を採用しても良い。
【００２５】
軸部材２は、例えば、ステンレス鋼等の金属材で形成され、その下側端部に、スラスト部材３と協働してスラスト軸受部Ｔを構成する凸球状の下側端面２ｂを備えている。
【００２６】
ハウジング７は、例えば、黄銅等の金属材で有底筒状に形成され、円筒状の側部７ｂと、側部７ｂと一体に設けられた下端側の底部７ｃとを備えている。また、側部７ｂの内周面７ｂ１と底部７ｃの内底面７ｃ１との間に段部７ｄが設けられ、段部７ｄは、内底面７ｃ１から軸方向上方に所定寸法だけ高くなった位置で当接面７ｄ１を形成する。側部７ｂの内周面７ｂ１は軸受スリーブ８の外周面と適合し、段部７ｄの当接面７ｄ１は軸受スリーブ８の下側端面８ｂと当接する。
【００２７】
スラスト部材３は、例えば、樹脂材料で円盤状に形成され、ハウジング７の内底面７ｃ１に配設される。スラスト部材３は、軸部材２の下側端面２ｂを支持するスラスト支持面３ａを有する。ハウジング７の段部７ｄの当接面７ｄ１は、スラスト支持面３ａから軸方向上方に所定寸法だけ高くなった位置にある。
【００２８】
シール部材４は、例えば、ＰＴＦＥ複合材等の樹脂材や黄銅等の金属材で形成され、ハウジング７の内周面７ｂ１の上端部に圧入固定される。シール部材４は、基部４ａと、基部４ａから軸方向下方に一体に延びた脚部４ｂとを備えている。基部４ａは、軸部材２の外周面２ａとの間にシール空間Ｓ１を形成する内周面４ａ１を有する。脚部４ｂは、基部４ａの内周面４ａ１よりも大径で、軸部材２の外周面２ａとの間に保油空間Ｓ２を形成する内周面４ｂ１と、軸受スリーブ８の上側端面８ｃと当接する当接面４ｂ２とを有する。
【００２９】
シール部材４は、ＰＴＦＥ複合材等の撥油性（油をはじく性質）を有する樹脂材で形成することにより、あるいは、金属材で形成する場合は、表面に撥油処理を施すことにより、少なくとも基部４ａの内周面４ａ１に（好ましくは上端面にも）撥油性（油をはじく性質）を与えておくのが好ましい。これにより、ハウジング７の内部空間の潤滑流体が外部に漏れ出すことを効果的に防止することができる。
【００３０】
この実施形態の流体軸受装置１は、例えば、次のような工程で組立てる。
【００３１】
まず、ハウジング７の内底面７ｃ１にスラスト部材３を配置する。その後、軸受スリーブ８をハウジング７の側部７ｂの内周面７ｂ１に挿入し、その下側端面８ｂをハウジング７の段部７ｄの当接面７ｄ１に当接させる。これにより、軸受スリーブ８がハウジング７に対して位置決めされる。
【００３２】
つぎに、シール部材４をハウジング７の側部７ｂの内周面７ｂに圧入し、その脚部４ｂの当接面４ｂ２が軸受スリーブ８の上側端面８ｃに当接するまで押し進める。これにより、シール部材４が側部７ｂの内周面７ｂ１の上端部に固定されると同時に、軸受スリーブ８が、ハウジング７の段部７ｄの当接面７ｄ１とシール部材４の脚部４ｂの当接面４ｂ２とで軸方向両側（上下方向）から挟持され、ハウジング７の内部に固定される。
【００３３】
その後、軸部材２を軸受スリーブ８の内周面８ａに挿入して、その下側端面２ｂをスラスト部材３のスラスト支持面３ａに接触させる。そして、シール部材４でシールされたハウジング７の内部空間に、軸受スリーブ８の内部気孔（多孔質体の組織気孔）を含めて、潤滑流体、例えば潤滑油を充満させる。保油空間Ｓ２はシール空間Ｓ１と連通し、潤滑油は保油空間Ｓ１にも充満され、その油面はシール空間Ｓ１内に維持される。
【００３４】
軸部材２の回転時、軸受スリーブ８の内周面８ａのラジアル軸受面となる領域（上下２箇所の領域）は、それぞれ、軸部材２の外周面２ａとラジアル軸受隙間を介して対向する。そして、軸部材２の回転に伴い、上記ラジアル軸受隙間に潤滑油の動圧が発生し、軸部材２が上記ラジアル軸受隙間内に形成される潤滑油の油膜によってラジアル方向に回転自在に非接触支持される。これにより、軸部材２をラジアル方向に回転自在に非接触支持する第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２とが構成される。同時に、軸部材２の下側端面２ｂがハウジング７の内底面７ｃ１に配設されたスラスト部材３のスラスト支持面３ａによって接触支持される。これにより、軸部材２をスラスト方向に回転自在に支持するスラスト軸受部Ｔが構成される。
【００３５】
図２は、第２の実施形態に係る流体軸受装置（流体動圧軸受装置）１１を示している。この実施形態の流体軸受装置１１が、第１の実施形態の流体軸受装置１と異なる点は、ハウジング１７を両端が開口した筒状に形成すると共に、ハウジング１７の下端部をスラスト部材１３によって閉塞した点、軸受スリーブ８の下側端面８ｂと当接する当接面１３ｂをスラスト部材１３に設けた点にある。
【００３６】
スラスト部材１３は、例えば、樹脂材で形成され、ハウジング１７の内周面１７ａの下端部に圧入固定される。スラスト部材１３は、軸部材２の下側端面２ｂを支持するスラスト支持面１３ａと、スラスト支持面１３ａの外周に設けられた段部１３ｂとを備え、段部１３ｂは、スラスト支持面１３ａから軸方向上方に所定寸法だけ高くなった位置で当接面１３ｂ１を形成する。
【００３７】
この実施形態において、軸受スリーブ８は、ハウジング１７の内周面１７ａに挿入され、スラスト部材１３の当接面１３ｂ１とシール部材４の脚部４ｂの当接面４ｂ２とで軸方向両側（上下方向）から挟持され、ハウジング７の内部に固定される。尚、スラスト部材１３を圧入した後、該圧入部分を接着剤で封止するようにしても良い。また、この実施形態では、シール部材４と同様の形態及び寸法のシール部をハウジング１７に一体形成することもできる。その他の事項は第１の実施形態に準じるので、重複する説明を省略する。
【００３８】
図３は、第３の実施形態に係る流体軸受装置（流体動圧軸受装置）２１を示している。この実施形態の流体軸受装置２１が、第１の実施形態の流体軸受装置１と異なる点は、ハウジング２７を樹脂材で形成すると共に、軸部材２の下側端面２ｂを支持するスラスト支持面２７ｃ１１と、軸受スリーブ８の下側端面８ｂと当接する当接面２７ｃ１２とを、ハウジング２７の底部２７ｃの内底面２７ｃ１に設けた点にある。第１の実施形態に比較して、別体のスラスト部材３は配置されておらず、また、スラスト支持面２７ｃ１１と当接面２７ｃ１２とが同一の高さレベルにある。
【００３９】
この実施形態において、軸受スリーブ８は、ハウジング２７の側部２７ｂの内周面２７ｂ１に挿入され、ハウジング２７の内底面２７Ｃ１の当接面２７ｃ１２とシール部材４の脚部４ｂの当接面４ｂ２とで軸方向両側（上下方向）から挟持され、ハウジング７の内部に固定される。その他の事項は第１の実施形態に準じるので、重複する説明を省略する。
【００４０】
以上の実施形態の流体軸受装置は、軸部材２の下側端面２ｂをスラスト支持面で支持する構成になっているが、本発明は、軸部材をスラスト動圧軸受部で非接触支持する構成の流体軸受装置にも適用可能である。
【００４１】
【発明の効果】
本発明によれば、組立工程が簡素で、より一層低コストで、かつ信頼性の高い流体軸受装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係る流体軸受装置を示す断面図である。
【図２】本発明の第２の実施形態に係る流体軸受装置を示す断面図である。
【図３】本発明の第３の実施形態に係る流体軸受装置を示す断面図である。
【符号の説明】
１、１１、２１流体軸受装置
２軸部材
２ａ外周面
２ｂ下側端面
７、１７、２７ハウジング
７ｄ１、２７ｃ１２当接面
８軸受スリーブ
８ａ内周面
３、１３スラスト部材
１３ｂ１当接面
Ｒ１第１ラジアル軸受部
Ｒ２第２ラジアル軸受部
Ｔスラスト軸受部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydrodynamic bearing device that supports a rotating member in a non-contact manner by an oil film of lubricating oil generated in a radial bearing gap. This bearing device is a spindle for information equipment, for example, a magnetic disk device such as an HDD or FDD, an optical disk device such as a CD-ROM, a CD-R / RW, a DVD-ROM / RAM, or a magneto-optical disk device such as an MD or MO. It is suitable for a motor, a polygon scanner motor of a laser beam printer (LBP), or a small motor such as an electric device such as an axial fan.
[0002]
[Prior art]
The above various motors are required to have high speed, low cost, low noise, etc. in addition to high rotational accuracy. One of the components that determine the required performance is a bearing that supports the spindle of the motor.In recent years, the use of a fluid bearing having characteristics excellent in the required performance has been studied or actually used. .
[0003]
Fluid bearings of this type include a so-called dynamic pressure bearing having a dynamic pressure generating means for generating dynamic pressure in lubricating oil in a bearing gap, and a so-called circular bearing without a dynamic pressure generating means (the bearing surface is a perfect circle). Bearings).
[0004]
For example, in a fluid bearing device incorporated in a spindle motor of a disk drive device such as an HDD or a polygon scanner motor of a laser beam printer (LBP), a radial bearing portion that rotatably supports a shaft member in a radial direction in a non-contact manner, and a shaft member. And a thrust bearing portion rotatably supporting the shaft in the thrust direction. A dynamic pressure generating groove (dynamic pressure groove) is provided as a radial bearing portion on the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member. A pressure bearing is used. As the thrust bearing portion, for example, a bearing (a so-called pivot bearing) having a structure in which the one end side end surface of the shaft member is supported by the thrust member is used. Usually, the bearing sleeve is fixed at a predetermined position on the inner periphery of the housing, and a seal member is often provided at the opening of the housing in order to prevent the lubricating oil in the internal space of the housing from leaking to the outside. For example, see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2001-124057
There is also a hydrodynamic bearing device in which a fixed space is provided between the seal member and the end surface of the bearing sleeve, and the space is used as an oil holding space (for example, see Patent Document 2).
[0007]
[Patent Document 1]
JP 2001-124057 A [Patent Document 2]
JP-A-11-108053
[Problems to be solved by the invention]
The hydrodynamic bearing device having the above-described configuration is configured with components such as a housing, a bearing sleeve, a shaft member, a thrust member, and a seal member, and in order to secure a high bearing performance required as information devices become more and more sophisticated. Efforts have been made to increase the processing accuracy and assembly accuracy of each part. On the other hand, with the trend of price reduction of information equipment, the demand for cost reduction of this type of hydrodynamic bearing device is becoming more and more severe.
[0009]
In the fluid bearing device having the above structure, the bearing sleeve is usually fixed to the inner periphery of the housing by an adhesive or press-fitting. In the former case, a plurality of steps such as application of the adhesive, holding of both parts, and drying and solidification of the adhesive are performed. Required, and it takes a relatively long time for the adhesive to solidify. In the latter case, depending on the interference at the time of press fitting, the inner peripheral surface of the bearing sleeve may be displaced toward the inner diameter side, causing a change in the bearing gap.
[0010]
Further, in a fluid bearing device in which a fixed space is provided between the seal member and the end surface of the bearing sleeve, the axial dimension of the space varies depending on the fixing position of the seal member and the bearing sleeve with respect to the housing. It is difficult to manage to a certain size.
[0011]
It is an object of the present invention to provide a highly reliable hydrodynamic bearing device with a simple assembling process, at a lower cost.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a housing, a bearing sleeve fixed inside the housing, a shaft member inserted into an inner peripheral surface of the bearing sleeve, an inner peripheral surface of the bearing sleeve, and an outer periphery of the shaft member. A radial bearing portion that is provided between the first and second surfaces and radially supports the shaft member with a lubricating oil film generated in a bearing gap; and a thrust bearing portion that is provided at one end of the housing and supports the shaft member in the thrust direction. And a seal portion provided on the other end side of the housing and sealing the inside of the housing. In the fluid dynamic bearing device, the bearing sleeve is formed by the contact portion provided on one end side of the housing and the seal portion in both axial directions. To provide a configuration fixed within the housing.
[0013]
According to the above configuration, the man-hour and time of the assembling process can be reduced as compared with the case where the bearing sleeve is fixed to the housing with an adhesive, and the bearing clearance can be reduced as compared with the case where the bearing sleeve is pressed into the housing. And stable bearing function can be secured.
[0014]
In the above configuration, the contact portion may be provided integrally with the housing, or may be provided on a thrust member fixed to one end of the housing.
[0015]
In order to solve the above problems, the present invention provides a housing, a bearing sleeve fixed inside the housing, a shaft member inserted into an inner peripheral surface of the bearing sleeve, an inner peripheral surface of the bearing sleeve, and a shaft member. A radial bearing portion provided between the outer peripheral surface of the housing and the radial direction for supporting the shaft member with a lubricating oil film generated in a bearing gap; and a thrust bearing provided on one end side of the housing and supporting the shaft member in the thrust direction. A fluid bearing device provided with a portion and a seal portion provided on the other end side of the housing to seal the inside of the housing, wherein the seal portion includes a base portion, and a leg portion extending from the base portion to one end side; Has an inner peripheral surface that forms a seal space with the outer peripheral surface of the shaft member, and the leg portion has a larger diameter than the inner peripheral surface of the base portion, and has an oil retention space between the outer peripheral surface of the shaft member. Of the inner sleeve and the bearing sleeve Providing a structure having an end-side end surface abutting abutment surface.
[0016]
When the contact surface of the leg portion of the seal portion is brought into contact with the one end surface of the bearing sleeve, the axial positional relationship between the two is determined. An oil retaining space is formed between the inner peripheral surface of the leg of the seal portion and the outer peripheral surface of the shaft member, and the space volume of the oil retaining space is determined by the inner diameter of the inner peripheral surface of the leg and the axial dimension. Depends on Therefore, by controlling the dimensions of the inner peripheral surface of the leg, the oil retaining space having a predetermined space volume can be easily formed simply by bringing the contact surface of the leg into contact with the one end side end surface of the bearing sleeve. It can be formed with high accuracy.
[0017]
In particular, in the fluid bearing device in which the interior space of the housing is filled with the lubricating fluid, the provision of the oil retaining space increases the amount of the lubricating fluid retained in the housing, suppresses the deterioration of the lubricating fluid, and reduces the bearing function. For a long time. In addition, since the oil retaining space can be formed with a predetermined space volume with high accuracy, the total amount of the lubricating fluid that fills the internal space of the housing can be managed with high accuracy.
[0018]
The above-mentioned seal portion can be formed integrally with the housing, or can be constituted by a seal member fixed to one end side of the housing. In the latter case, the base and the leg of the seal portion may be formed by separate ring members, but from the viewpoint of reducing the number of parts, it is preferable that the base and the leg are integrally formed. Further, it is preferable that at least the inner peripheral surface of the base portion of the seal portion has oil repellency.
[0019]
Further, in the above configuration, the bearing sleeve is fixed to the inside of the housing by sandwiching the bearing sleeve from both sides in the axial direction between the contact portion provided on one end side of the housing and the contact surface of the leg portion of the seal portion. be able to.
[0020]
In the above configuration, the radial bearing portion can be a dynamic pressure bearing that generates a dynamic pressure of lubricating oil in the bearing gap.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0022]
FIG. 1 shows a hydrodynamic bearing device (fluid dynamic bearing device) 1 according to the first embodiment. The hydrodynamic bearing device 1 is incorporated in, for example, a spindle motor of a disk drive such as an HDD or a polygon scanner motor of a laser beam printer (LBP), and includes a housing 7, a bearing sleeve 8, a shaft member 2, and a thrust member. The member 3 and the seal member 4 are configured as constituent parts.
[0023]
A first radial bearing portion R1 and a second radial bearing portion R2 are provided between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a of the shaft member 2 so as to be separated in the axial direction. In addition, a thrust bearing portion T is provided between the lower end surface 2b of the shaft member 2 and the thrust member 3 disposed on the bottom 7c of the housing 7. For convenience of description, the description will be made with the side of the thrust bearing portion T being the lower side and the side opposite to the thrust bearing portion T being the upper side.
[0024]
The bearing sleeve 8 is formed of, for example, a porous body made of a sintered metal, in particular, a porous body of a sintered metal containing copper as a main component. On the inner peripheral surface 8a of the bearing sleeve 8 formed of this sintered metal, two upper and lower regions serving as radial bearing surfaces of a first radial bearing portion R1 and a second radial bearing portion R2 are provided axially separated. In the two regions, for example, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 are formed, respectively. The dynamic pressure groove may have a spiral shape, an axial groove shape, or the like.
[0025]
The shaft member 2 is formed of, for example, a metal material such as stainless steel, and has, at its lower end, a lower end surface 2 b of a convex sphere that forms a thrust bearing portion T in cooperation with the thrust member 3. .
[0026]
The housing 7 is formed of a metal material such as brass, for example, in the shape of a bottomed cylinder, and includes a cylindrical side part 7b and a bottom part 7c at the lower end provided integrally with the side part 7b. A step 7d is provided between the inner peripheral surface 7b1 of the side portion 7b and the inner bottom surface 7c1 of the bottom portion 7c. The step 7d is positioned at a position higher than the inner bottom surface 7c1 by a predetermined dimension in the axial direction. The contact surface 7d1 is formed. The inner peripheral surface 7b1 of the side portion 7b conforms to the outer peripheral surface of the bearing sleeve 8, and the contact surface 7d1 of the step portion 7d contacts the lower end surface 8b of the bearing sleeve 8.
[0027]
The thrust member 3 is formed, for example, in a disk shape from a resin material, and is disposed on the inner bottom surface 7c1 of the housing 7. The thrust member 3 has a thrust support surface 3a that supports the lower end surface 2b of the shaft member 2. The contact surface 7d1 of the step 7d of the housing 7 is located at a position higher than the thrust support surface 3a by a predetermined dimension in the axial direction.
[0028]
The seal member 4 is formed of, for example, a resin material such as a PTFE composite material or a metal material such as brass, and is press-fitted and fixed to the upper end of the inner peripheral surface 7b1 of the housing 7. The seal member 4 includes a base 4a and a leg 4b integrally extending from the base 4a downward in the axial direction. The base 4a has an inner peripheral surface 4a1 that forms a seal space S1 with the outer peripheral surface 2a of the shaft member 2. The leg portion 4b has a larger diameter than the inner peripheral surface 4a1 of the base portion 4a, and has an inner peripheral surface 4b1 forming an oil retaining space S2 between itself and the outer peripheral surface 2a of the shaft member 2, and an upper end surface 8c of the bearing sleeve 8. And an abutting surface 4b2 that abuts.
[0029]
The seal member 4 is formed of a resin material having oil repellency (oil repelling property) such as a PTFE composite material, or, when formed of a metal material, is subjected to an oil repellent treatment on a surface thereof, so that at least the base portion is formed. It is preferable that oil repellency (oil repelling property) is given to the inner peripheral surface 4a1 of the 4a (preferably also to the upper end surface). Thereby, it is possible to effectively prevent the lubricating fluid in the internal space of the housing 7 from leaking to the outside.
[0030]
The hydrodynamic bearing device 1 of this embodiment is assembled in the following steps, for example.
[0031]
First, the thrust member 3 is disposed on the inner bottom surface 7c1 of the housing 7. Thereafter, the bearing sleeve 8 is inserted into the inner peripheral surface 7b1 of the side portion 7b of the housing 7, and the lower end surface 8b is brought into contact with the contact surface 7d1 of the step portion 7d of the housing 7. Thereby, the bearing sleeve 8 is positioned with respect to the housing 7.
[0032]
Next, the seal member 4 is pressed into the inner peripheral surface 7b of the side portion 7b of the housing 7, and is pushed forward until the contact surface 4b2 of the leg portion 4b contacts the upper end surface 8c of the bearing sleeve 8. As a result, the seal member 4 is fixed to the upper end of the inner peripheral surface 7b1 of the side portion 7b, and at the same time, the bearing sleeve 8 is connected to the contact surface 7d1 of the step 7d of the housing 7 and the leg 4b of the seal member 4. It is sandwiched between the contact surfaces 4b2 from both sides in the axial direction (vertical direction) and is fixed inside the housing 7.
[0033]
Thereafter, the shaft member 2 is inserted into the inner peripheral surface 8a of the bearing sleeve 8, and the lower end surface 2b is brought into contact with the thrust support surface 3a of the thrust member 3. Then, a lubricating fluid, for example, lubricating oil is filled in the inner space of the housing 7 sealed by the seal member 4, including the internal pores (tissue pores of the porous body) of the bearing sleeve 8. The oil holding space S2 communicates with the seal space S1, the lubricating oil is also filled in the oil holding space S1, and the oil level is maintained in the seal space S1.
[0034]
When the shaft member 2 rotates, regions (two upper and lower regions) of the inner peripheral surface 8a of the bearing sleeve 8 to be radial bearing surfaces respectively oppose the outer peripheral surface 2a of the shaft member 2 via the radial bearing gap. Then, with the rotation of the shaft member 2, a dynamic pressure of the lubricating oil is generated in the radial bearing gap, and the shaft member 2 is rotatably non-contacted in the radial direction by an oil film of the lubricating oil formed in the radial bearing gap. Supported. Thus, a first radial bearing portion R1 and a second radial bearing portion R2 that rotatably support the shaft member 2 in the radial direction in a non-contact manner are configured. At the same time, the lower end surface 2b of the shaft member 2 is contacted and supported by the thrust support surface 3a of the thrust member 3 disposed on the inner bottom surface 7c1 of the housing 7. Thus, a thrust bearing portion T that rotatably supports the shaft member 2 in the thrust direction is configured.
[0035]
FIG. 2 shows a hydrodynamic bearing device (fluid dynamic bearing device) 11 according to the second embodiment. The hydrodynamic bearing device 11 of this embodiment differs from the hydrodynamic bearing device 1 of the first embodiment in that the housing 17 is formed in a cylindrical shape with both ends opened, and the lower end of the housing 17 is closed by a thrust member 13. That is, the contact surface 13 b that contacts the lower end surface 8 b of the bearing sleeve 8 is provided on the thrust member 13.
[0036]
The thrust member 13 is formed of, for example, a resin material, and is press-fitted and fixed to a lower end portion of the inner peripheral surface 17 a of the housing 17. The thrust member 13 includes a thrust support surface 13a that supports the lower end surface 2b of the shaft member 2, and a step 13b provided on the outer periphery of the thrust support surface 13a. The contact surface 13b1 is formed at a position higher by a predetermined dimension in the direction above.
[0037]
In this embodiment, the bearing sleeve 8 is inserted into the inner peripheral surface 17a of the housing 17, and the axially opposite sides (up and down direction) of the abutting surface 13b1 of the thrust member 13 and the abutting surface 4b2 of the leg 4b of the seal member 4 are provided. ) And is fixed inside the housing 7. After the thrust member 13 is press-fitted, the press-fitted portion may be sealed with an adhesive. Further, in this embodiment, a seal portion having the same form and dimensions as the seal member 4 can be formed integrally with the housing 17. Other items are the same as those in the first embodiment, and a duplicate description will be omitted.
[0038]
FIG. 3 shows a hydrodynamic bearing device (fluid dynamic pressure bearing device) 21 according to the third embodiment. The hydrodynamic bearing device 21 of this embodiment differs from the hydrodynamic bearing device 1 of the first embodiment in that the housing 27 is formed of a resin material and the thrust support surface 27c11 that supports the lower end surface 2b of the shaft member 2. And a contact surface 27c12 that contacts the lower end surface 8b of the bearing sleeve 8 on the inner bottom surface 27c1 of the bottom 27c of the housing 27. Compared to the first embodiment, no separate thrust member 3 is provided, and the thrust support surface 27c11 and the contact surface 27c12 are at the same height level.
[0039]
In this embodiment, the bearing sleeve 8 is inserted into the inner peripheral surface 27b1 of the side portion 27b of the housing 27, and contacts the contact surface 27c12 of the inner bottom surface 27C1 of the housing 27 and the contact surface 4b2 of the leg 4b of the seal member 4. And is fixed in the housing 7 from both sides in the axial direction (vertical direction). Other items are the same as those in the first embodiment, and a duplicate description will be omitted.
[0040]
The hydrodynamic bearing device of the above embodiment has a configuration in which the lower end surface 2b of the shaft member 2 is supported by the thrust support surface. However, the present invention provides a configuration in which the shaft member is non-contact supported by the thrust dynamic pressure bearing portion. The present invention is also applicable to the hydrodynamic bearing device.
[0041]
【The invention's effect】
According to the present invention, it is possible to provide a highly reliable hydrodynamic bearing device with a simple assembling process, at even lower cost.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a hydrodynamic bearing device according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a hydrodynamic bearing device according to a second embodiment of the present invention.
FIG. 3 is a sectional view showing a hydrodynamic bearing device according to a third embodiment of the present invention.
[Explanation of symbols]
1, 11, 21 Fluid bearing device 2 Shaft member 2a Outer peripheral surface 2b Lower end surface 7, 17, 27 Housing 7d1, 27c12 Contact surface 8 Bearing sleeve 8a Inner peripheral surface 3, 13 Thrust member 13b1 Contact surface R1 First radial Bearing part R2 Second radial bearing part T Thrust bearing part

Claims

ハウジングと、該ハウジングの内部に固定された軸受スリーブと、該軸受スリーブの内周面に挿入された軸部材と、前記軸受スリーブの内周面と前記軸部材の外周面との間に設けられ、軸受隙間に生じる潤滑油の油膜で前記軸部材をラジアル方向に支持するラジアル軸受部と、前記ハウジングの一端側に設けられ、前記軸部材をスラスト方向に支持するスラスト軸受部と、前記ハウジングの他端側に設けられ、前記ハウジングの内部をシールするシール部とを備えた流体軸受装置において、
前記軸受スリーブを、前記ハウジングの一端側に設けた当接部と前記シール部とで軸方向の両側から挟持して、前記ハウジングの内部に固定したことを特徴とする流体軸受装置。A housing, a bearing sleeve fixed inside the housing, a shaft member inserted into an inner peripheral surface of the bearing sleeve, and a shaft member provided between an inner peripheral surface of the bearing sleeve and an outer peripheral surface of the shaft member. A radial bearing portion for supporting the shaft member in a radial direction with an oil film of a lubricating oil generated in a bearing gap; a thrust bearing portion provided on one end side of the housing for supporting the shaft member in a thrust direction; A fluid bearing device provided on the other end side and having a seal portion for sealing the inside of the housing.
A fluid bearing device, wherein the bearing sleeve is sandwiched between an abutting portion provided on one end side of the housing and the seal portion from both sides in the axial direction, and is fixed inside the housing.

前記当接部は、前記ハウジングに一体に設けられていることを特徴とする請求項１に記載の流体軸受装置。The hydrodynamic bearing device according to claim 1, wherein the contact portion is provided integrally with the housing.

前記当接部は、前記ハウジングの一端部に固定されたスラスト部材に設けられていることを特徴とする請求項１に記載の流体軸受装置。2. The hydrodynamic bearing device according to claim 1, wherein the contact portion is provided on a thrust member fixed to one end of the housing. 3.

ハウジングと、該ハウジングの内部に固定された軸受スリーブと、該軸受スリーブの内周面に挿入された軸部材と、前記軸受スリーブの内周面と前記軸部材の外周面との間に設けられ、軸受隙間に生じる潤滑油の油膜で前記軸部材をラジアル方向に支持するラジアル軸受部と、前記ハウジングの一端側に設けられ、前記軸部材をスラスト方向に支持するスラスト軸受部と、前記ハウジングの他端側に設けられ、前記ハウジングの内部をシールするシール部とを備えた流体軸受装置において、
前記シール部は、基部と、該基部から一端側に延びた脚部とを備え、
前記基部は、前記軸部材の外周面との間にシール空間を形成する内周面を有し、前記脚部は、前記基部の内周面よりも大径で、前記軸部材の外周面との間に保油空間を形成する内周面と、前記軸受スリーブの一端側端面と当接する当接面とを有することを特徴とする流体軸受装置。A housing, a bearing sleeve fixed inside the housing, a shaft member inserted into an inner peripheral surface of the bearing sleeve, and a shaft member provided between an inner peripheral surface of the bearing sleeve and an outer peripheral surface of the shaft member. A radial bearing portion for supporting the shaft member in a radial direction with an oil film of a lubricating oil generated in a bearing gap; a thrust bearing portion provided on one end side of the housing for supporting the shaft member in a thrust direction; A fluid bearing device provided on the other end side and having a seal portion for sealing the inside of the housing.
The seal portion includes a base and a leg extending from the base to one end,
The base has an inner peripheral surface that forms a seal space with the outer peripheral surface of the shaft member, and the leg portion has a larger diameter than the inner peripheral surface of the base, and has an outer peripheral surface of the shaft member. A fluid bearing device comprising: an inner peripheral surface that forms an oil retaining space therebetween; and a contact surface that contacts an end surface on one end side of the bearing sleeve.

前記シール部を、前記ハウジングの一端側に固定したシール部材によって構成したことを特徴とする請求項４に記載の流体軸受装置。5. The hydrodynamic bearing device according to claim 4, wherein the seal portion is formed by a seal member fixed to one end of the housing. 6.

前記シール部の少なくとも基部の内周面が撥油性を有することを特徴とする請求項４又は５に記載の流体軸受装置。The hydrodynamic bearing device according to claim 4, wherein at least an inner peripheral surface of a base of the seal portion has oil repellency.

前記軸受スリーブを、前記ハウジングの一端側に設けた当接部と前記シール部の脚部の当接面とで軸方向の両側から挟持して、前記ハウジングの内部に固定したことを特徴とする請求項４から６の何れかに記載の流体軸受装置。The bearing sleeve is sandwiched from both sides in the axial direction by a contact portion provided on one end side of the housing and a contact surface of a leg portion of the seal portion, and is fixed inside the housing. The hydrodynamic bearing device according to claim 4.

前記ラジアル軸受部が、前記軸受隙間内に潤滑油の動圧を発生させる動圧軸受である請求項１から７の何れかに記載の流体軸受装置。The fluid bearing device according to any one of claims 1 to 7, wherein the radial bearing portion is a dynamic pressure bearing that generates a dynamic pressure of lubricating oil in the bearing gap.