JP3856977B2

JP3856977B2 - Bearing device and related technology

Info

Publication number: JP3856977B2
Application number: JP04385299A
Authority: JP
Inventors: 省三猪原; 義人奥
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 1999-02-22
Filing date: 1999-02-22
Publication date: 2006-12-13
Anticipated expiration: 2019-02-22
Also published as: JP2000240642A

Description

【０００１】
【発明の属する技術分野】
本発明は、記録媒体の駆動に用いられるスピンドルモータ等に使用されるラジアル軸受部とスラスト軸受部を備えた滑り軸受装置、及びその軸受装置を備えた回転機械に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
高容量フロッピーディスク、光磁気ディスク、ＣＤ−ＲＯＭ、ＤＶＤ、ハードディスク等の記録媒体の駆動に用いられるスピンドルモータ等の軸受装置として、図３に示されるような滑り軸受装置が知られている。この滑り軸受装置は、軸部ａの上端部付近に環状板状のスラスト鍔状部ｂを備えてなる固定軸体ｃに対し、その固定軸体ｃに外嵌した状態の回転スリーブ体ｄが、それらの軸心線を中心として同軸状に回転し得るよう支持されている。
【０００３】
回転スリーブ体ｄは、スリーブ部材ｅと環状のスラスト支持板ｆからなる。スリーブ部材ｅは、スリーブ部ｅ１と、そのスリーブ部ｅ１の上側に位置し、前記スリーブ部ｅ１よりも内径が拡大している中内径部ｅ２と、その中内径部ｅ２の上側に隣接して中内径部ｅ２よりも内径が拡大している大内径部ｅ３からなる。中内径部ｅ２の内周面とスリーブ部ｅ１の内周面の境界部は、軸心線に垂直な環状のスラスト支持面ｅ４に形成され、中内径部ｅ２の内周面と大内径部ｅ３の内周面の境界部は、軸心線に対し垂直な環状面ｅ５に形成されている。この環状面ｅ５に前記スラスト支持板ｆの下面が当接する状態で、そのスラスト支持板ｆが大内径部ｅ３に内嵌固定されている。
【０００４】
固定軸体ｃの軸部ａに対しては、回転スリーブ体ｄにおけるスリーブ部材ｅのスリーブ部ｅ１がスリーブ嵌合して、軸部ａの外周面とスリーブ部材ｅの内周面が径方向に相対した状態でラジアル滑り軸受部を構成している。
【０００５】
固定軸体ｃのスラスト鍔状部ｂは、下面がスラスト支持面ｅ４に、上面がスラスト支持板ｆの下面に、それぞれ軸心方向に相対した状態でスラスト滑り軸受部を構成している。
【０００６】
この従来の滑り軸受装置においては、使用中に固定軸体ｃと回転スリーブ体ｄとの間に焼付きが容易に生じることを防ぐために、回転スリーブ体ｄの各部材をブロンズ材等の比較的に軟らかい材料により形成し、固定軸体ｃの各部材をステンレス鋼等の比較的に硬い材料により形成している。そのため、周速が速いスラスト滑り軸受部において、ブロンズ材製のスリーブ部材ｅのスラスト支持面ｅ４又はスラスト支持板ｆの下面がステンレス鋼製のスラスト鍔状部ｂにより損傷を受けることや、固定軸体ｃに対するスラスト鍔状部ｂの直角度が悪い場合、スラスト鍔状部ｂの外周縁により損傷を受けること、スラスト鍔状部ｂに設けられた動圧溝のエッジにより損傷を受けることがあり、スリーブ部材ｅのスラスト支持面ｅ４又はスラスト支持板ｆの下面が磨耗することが生じ易いものとなっていた。更にブロンズ材製のスリーブ部材ｅのスラスト支持面ｅ４は工法上粗さ精度が出しにくいため、微小な凹凸があり、スラスト鍔状部ｂにより磨耗し易いものとなっていた。
【０００７】
また、ラジアル滑り軸受部及びスラスト滑り軸受部における軸受隙間をそれぞれ適切なものとするには、ラジアル滑り軸受部についてはスリーブ部材ｅにおけるスリーブ部ｅ１の内径の寸法が固定軸体ｃの軸部ａの外径の寸法に対し適切であれば良く、スラスト滑り軸受部については、スラスト支持面ｅ４とスラスト支持板ｆの下面の軸心方向間隔が、固定軸体ｃのスラスト鍔状部ｂにおける上下両面間の軸心方向寸法に対し適切であれば良い。
【０００８】
ところが、スラスト支持面ｅ４とスラスト支持板ｆの下面の軸心方向間隔を適切なものとするには、スリーブ部材ｅにおける、スラスト支持板ｆの下面が当接する環状面ｅ５とスラスト支持面ｅ４の軸心方向間隔をスラスト鍔状部ｂの上下両面間の軸心方向寸法に対し適切なものとする必要がある。
【０００９】
すなわち、スリーブ部材ｅについては、スリーブ部ｅ１の内径寸法と、環状面ｅ５とスラスト支持面ｅ４の軸心方向間隔を、軸部ａの外径寸法及びスラスト鍔状部ｂの上下両面間の軸心方向寸法に対し同時に満足させる必要がある。そのため、スリーブ部材ｅの加工に要求される精度が厳しいものとなり、全体としての製造コストを上昇させる要因ともなっていた。
【００１０】
本発明は、従来技術に存した上記のような問題点に鑑み行われたものであって、その目的とするところは、ラジアル軸受部とスラスト軸受部を備えた滑り軸受装置であって、ラジアル軸受部においてもスラスト軸受部においても焼付きが生じ難く且つスラスト軸受部の損傷若しくは摩耗及びそれによる回転精度の低下が効果的に防がれる軸受装置及びその軸受装置を備えた回転機械、並びに、スリーブ部の内径寸法とスラスト鍔状部に対する軸心方向の寸法を同時に満足することを必要とせず、スリーブ部材の加工が容易で全体として製造容易な軸受装置及びその軸受装置を備えた回転機械を提供することにある。
【００１１】
【課題を解決するための手段】
上記の目的を達成する本発明の軸受装置は、
軸部とその軸部よりも径方向外方に張り出したスラスト鍔状部を備えてなる軸体と、
スリーブ部と、そのスリーブ部の一端側に位置し、前記スリーブ部よりも内径が拡大している大内径部を備えてなるスリーブ部材とを有してなり、
前記スリーブ部が軸部にスリーブ嵌合して、前記スリーブ部の内周面と前記軸部の外周面との少なくとも一方に動圧溝を有し当該両面間に潤滑油を介在させてなるラジアル軸受部を構成し、前記大内径部内に前記スラスト鍔状部が位置し、軸体とスリーブ部材がそれらの軸心線を中心として同軸状に相対回転し得る軸受装置であって、
前記大内径部内には、軸心方向に相対する第１スラスト支持部及び第２スラスト支持部をそれぞれ有する第１スラスト部材及び第２スラスト部材が配設されてそれらがスリーブ部材に固定され、
前記第１スラスト部材と前記第２スラスト部材との間に前記スラスト鍔状部が挟まれて、前記第１スラスト支持部及び第２スラスト支持部と前記スラスト鍔状部における軸心方向両面とのそれぞれの間に、互いの対向面のスラスト鍔状部側に動圧溝を有し当該対向面間に潤滑油を介在させてなるスラスト軸受部を構成し、
前記スリーブ部の内周面に比し、前記軸部の外周面及び前記スラスト鍔状部における軸心方向両面の方が硬く、前記スラスト鍔状部における軸心方向両面に比し、第１スラスト支持部及び第２スラスト支持部の方が硬いことを特徴とする（請求項１）。
【００１２】
スリーブ部の内周面に比し軸部の外周面の方が硬く、スラスト鍔状部における軸心方向両面に比し、第１スラスト支持部及び第２スラスト支持部の方が硬いので、スリーブ部と軸部の間においても、また第１スラスト支持部及び第２スラスト支持部とスラスト鍔状部の間においても焼付きが生じ難い。而も、スラスト鍔状部における軸心方向両面に比し、第１スラスト支持部及び第２スラスト支持部の方が硬いので、第１スラスト支持部又は第２スラスト支持部がスラスト鍔状部の外周縁により損傷することや、第１スラスト部材及び第２スラスト部材とスラスト鍔状部との間の摩耗による回転精度の低下が効果的に防がれる。
【００１３】
軸体の軸部とスラスト鍔状部は、別体のものを結合させたものとすることができる他、一体物であってもよい。軸体の形状は、例えば、軸部は略円柱形状とすることができ、スラスト鍔状部は環状の板状をなすものとすることができる。軸体におけるスラスト鍔状部の位置は、軸部の一端部付近とすることができる。
【００１４】
スリーブ部材のスリーブ部が軸体の軸部にスリーブ嵌合して構成するラジアル軸受部においては、スリーブ部の内周面と軸部の外周面が潤滑剤を介して径方向に相対する。潤滑剤としては、例えばスピンドル油等の潤滑油を適宜選択して使用し得る。
【００１５】
スリーブ部材におけるスリーブ部の一端側に位置し、そのスリーブ部よりも内径が拡大している大内径部内に配設された第１スラスト部材及び第２スラスト部材における第１スラスト支持部と第２スラスト支持部の間にスラスト鍔状部が挟まれてスラスト軸受部を構成する。すなわちスラスト鍔状部の軸心方向両面が前記のような潤滑剤を介して第１スラスト支持部及び第２スラスト支持部に相対する。このスラスト軸受部においては、例えば、第１スラスト支持部及び第２スラスト支持部がそれぞれ環状面状をなし、第１スラスト支持部及び第２スラスト支持部、並びにスラスト鍔状部の軸心方向両面のうち第１スラスト支持部及び第２スラスト支持部に相対してスラスト軸受部を構成する部分が、それぞれ軸心方向に対し垂直状をなすものとすることができる。
【００１６】
大内径部の内周面は、例えば、スリーブ部と同軸状をなす円筒面形状とすることができる。また、大内径部の内周面とスリーブ部の内周面との境界部分は、例えば、軸心方向に対し垂直な環状面状に構成することができる。
【００１７】
第１スラスト部材及び第２スラスト部材の形状は、例えば環状板状とすることができる
【００１８】
軸体と、第１スラスト部材及び第２スラスト部材がスリーブ部材に固定されてなるスリーブ体は、それらの軸心線を中心として同軸状に相対回転し得る。この軸受装置は、軸体が固定されてスリーブ体の側が回転するものの他、スリーブ体の側が固定され軸体が回転するものとすることも可能である。
【００１９】
軸部の外周面とスラスト鍔状部における軸心方向両面とは、同一硬さとしてもよく異なる硬さとすることもできる。スラスト鍔状部における軸心方向両面というのは、軸心方向が上下方向であるならば、スラスト鍔状部における上下両面を言う。スラスト鍔状部における軸心方向両面、並びに第１スラスト支持部と第２スラスト支持部は、それぞれ、通常の場合同一硬さとする。例えば、スリーブ部の内周面をブロンズ材により、軸部の外周面及びスラスト鍔状部における軸心方向両面をステンレス鋼により構成し、そのステンレス鋼よりも硬いステンレス鋼により第１スラスト支持部及び第２スラスト支持部を構成するものとすることができる。
【００２０】
本発明の軸受装置は、スリーブ部材、軸部、スラスト鍔状部、第１スラスト部材及び第２スラスト部材のそれぞれが、一定の面のみならず全体として一定硬さであり、スリーブ部材に比し、軸部及びスラスト鍔状部の方が硬く、そのスラスト鍔状部に比し、第１スラスト部材及び第２スラスト部材の方が硬いものとすることができる。この場合、軸部及びスラスト鍔状部は比較的に硬いこととなるので、軸部とスラスト鍔状部が別体であって軸部に対しスラスト鍔状部がしまりばめにより外嵌固定されているときにおける軸部とスラスト鍔状部との間の抜け強度（嵌合強度〉が比較的に高い。
【００２１】
本発明の軸受装置は、第１スラスト部材又は第２スラスト部材の一方が、スラスト鍔状部よりも径方向外方に、他方のスラスト部材に向かって突出してそのスラスト部材に当接したスペーサ部を有し、そのスペーサ部の軸心方向寸法によって、第１スラスト支持部と第２スラスト支持部の軸心方向間隔が定まっているものとすることができる（請求項２）。
【００２２】
ラジアル軸受部及びスラスト軸受部における軸受隙間をそれぞれ適切なものとするには、ラジアル軸受部についてはスリーブ部材におけるスリーブ部の内径の寸法が軸体の軸部の外径の寸法に対し適切であれば良く、スラスト軸受部については、第１スラスト支持部と第２スラスト支持部の軸心方向間隔が、軸体のスラスト鍔状部における軸心方向両面間の軸心方向寸法に対し適切であれば良い。第１スラスト支持部と第２スラスト支持部の軸心方向間隔を適切なものとするには、スリーブ部材の大内径部内に配設する第１スラスト部材及び第２スラスト部材のうち一方が有するスペーサ部の軸心方向寸法を適切なものとすれば良い。従って、スリーブ部材の寸法に関しては、そのスリーブ部の内径寸法が軸部の外径の寸法に対し適切であれば良く、スリーブ部の内径寸法とスラスト鍔状部に対する軸心方向の寸法を同時に満足することを要しない。そのため、スリーブ部材の加工が容易であり、全体として製造容易である。
【００２３】
スペーサ部は、例えば、環状突部、特に、軸心線を中心とした回転対称状をなす環状突部とすることができ、また、内周面が軸心線と同軸状の円筒面状をなす環状突部とすることができる。このような環状突部は、例えば、軸心方向に対し垂直な面を基準として一方のスラスト部材から軸心方向に一定長さ突出して他方のスラスト部材に当接するものとすることができる。
【００２４】
本発明の軸受装置は、スラスト鍔状部よりも径方向外方における第１スラスト部材と第２スラスト部材の間に、それらと別体のスペーサ部材が配設され、そのスペーサ部材の軸心方向両方の面がそれぞれ第１スラスト部材と第２スラスト部材に当接しており、そのスペーサ部材の軸心方向寸法によって、第１スラスト支持部と第２スラスト支持部の軸心方向間隔が定まっているものとすることができる（請求項３）。
【００２５】
この場合も前記と同様に、第１スラスト支持部と第２スラスト支持部の軸心方向間隔を適切なものとするには、スリーブ部材の大内径部内に位置する第１スラスト部材及び第２スラスト部材の間に配設するスペーサ部材の軸心方向寸法を適切なものとすれば良い。従って、スリーブ部材の寸法に関しては、そのスリーブ部の内径寸法が軸部の外径の寸法に対し適切であれば良く、スリーブ部の内径寸法とスラスト鍔状部に対する軸心方向の寸法を同時に満足することを要しないので、スリーブ部材の加工が容易であり、全体として製造容易である。
【００２６】
この場合のスペーサ部材は、第１スラスト部材及び第２スラスト部材とは別体であり、例えば、環状部材、特に、軸心線を中心とした回転対称状をなす環状部材とすることができ、また、内周面が軸心線と同軸状の円筒面状をなす環状部材とすることができる。このような環状部材は、例えば、軸心方向両方の面がそれぞれ第１スラスト部材と第２スラスト部材に当接する状態で大内径部に内嵌固定されるものとすることができる。
スペーサ部材の線膨張率は、温度補償を考慮して、スラスト鍔状部の線膨張率より大きくすることが望ましい（請求項４）。
【００２７】
本発明の回転機械は、上記本発明の軸受装置を備えたものとすることができる（請求項５）。
【００２８】
この回転機械の例としては、軸受装置として上記本発明の軸受装置を採用した、スピンドルモータを始めとする電動機を挙げることができる。但し、必ずしもこれに限るものではない。なお、前記スピンドルモータとしては、高容量フロッピーディスク、光磁気ディスク、ＣＤ−ＲＯＭ、ＤＶＤ、ハードディスク等の記録媒体の回転駆動に用いるものを例示することができる。
【００２９】
【発明の実施の形態】
本発明の実施の形態を、図面を参照しつつ説明する。
【００３０】
図１は、本発明の滑り軸受装置を備えたスピンドルモータの実施の形態の一例としての、ハードディスク駆動用のスピンドルモータ（ブラシレスＤＣモータ）の断面図である。
【００３１】
ベースプレート１０は、上方開口の環状凹部１２と、その環状凹部１２の内周側において円筒状に上方に突出するステータ支持部１４と、中央部の嵌合孔１６を有してなる。
【００３２】
固定軸体１８は、円柱状の軸部材２０の上部に円環状の板形状のスラスト鍔状部材２２が外嵌固定されてなり、ベースプレート１０に対し、軸部材２０の下端部が嵌合孔１６に嵌合固定されることにより垂直上向きに立設されている。軸部材２０及びスラスト鍔状部材２２は同一のステンレス鋼製である。
【００３３】
ステータ支持部１４には、ステータコイル２４が巻回されたステータコア２６が外嵌固定され、そのステータコイル２４の引出部２４ａが、ベースプレート１０の底部を貫通し且つ封止された引出孔１０ａを通じて、下方へ引き出されている。
【００３４】
回転スリーブ体５０は、ブロンズ材製のスリーブ部材５２と、軸部材２０及びスラスト鍔状部材２２を構成するステンレス鋼よりも硬いステンレス鋼製の円環状の板状の下スラスト部材５４及び上スラスト部材５６と、円環状のスペーサ部材５８からなる。軸部材２０とスラスト鍔状部材２２は焼き嵌めにより結合されており、ブロンズ材よりも硬いステンレス鋼製であるため抜け強度が比較的に高い。
【００３５】
スリーブ部材５２は、内径が一定の円筒面形状であるスリーブ部５２ａと、そのスリーブ部５２ａの上端側に隣接して位置した大内径部５２ｂからなる。大内径部５２ｂの内周面は、前記スリーブ部５２ａの内周面と同軸状に内径が拡大した一定内径の円筒面形状である。大内径部５２ｂの内周面とスリーブ部５２ａの内周面との境界部分は、軸心方向に対し垂直な環状拡径面５２ｃに形成されている。スリーブ部材５２の外径についても、内径と同様、スリーブ部５２ａの外径よりも大内径部５２ｂの外径の方が拡大している。
【００３６】
下スラスト部材５４、スペーサ部材５８及び上スラスト部材５６は、この順に環状拡径面５２ｃ上に積み重なった状態で大内径部５２ｂの内周面に対し同軸状に内嵌固定されている。下スラスト部材５４及び上スラスト部材５６の内径は軸部材２０の外径よりもやや大きく、スペーサ部材５８の内径はスラスト鍔状部材２２の外径よりもやや大きい。
【００３７】
回転スリーブ体５０の下スラスト部材５４と上スラスト部材５６の間にスラスト鍔状部材２２が挟まれてスラスト軸受部８０を構成する。スラスト鍔状部材２２の下上両面は、それぞれ動圧発生用溝部を有し、潤滑油を介して下スラスト部材５４の上面（第１スラスト支持部）及び上スラスト部材５６の下面（第２スラスト支持部）に軸心方向に相対する。下スラスト部材５４の内周縁部上側及び上スラスト部材５６の内周縁部下側は何れも径方向内方に向かってスラスト鍔状部材２２との軸心方向間隙が漸次拡大する上下のテーパ部に形成され、スラスト鍔状部材２２と下スラスト部材５４及び上スラスト部材５６の間の潤滑油の内方界面が表面張力によりこれらのテーパ部に保持されるよう構成されている。また潤滑油中の気泡がこれらのテーパ部における潤滑油の内方界面を経て気体側に開放されるように潤滑油が循環する循環路２２ａがスラスト鍔状部材２２内に設けられており、この循環路はスラスト鍔状部材２２の外周面と上下のテーパ部の外周側部分に開口する。またスラスト鍔状部材２２の内周部に、軸部材２０の外周面との間で上下のテーパ部の内周側部分を連通する上下連通孔を形成する連通用溝部２２ｂが設けられている。
【００３８】
軸部材２０のうちスラスト鍔状部材２２よりも下方であってベースプレート１０よりも上方の部分にスリーブ部５２ａがスリーブ嵌合してラジアル軸受部９０を構成する。軸部材２０のこの部分の外周面の上部及び下部にそれぞれ動圧発生用溝部を有し、潤滑油を介してスリーブ部５２ａの内周面と径方向に相対する。軸部材２０のうち両動圧発生用溝部の間の部分の外径はやや縮径されている。軸部材２０のうちスリーブ部５２ａの下端部に相対する部分の外径は、下方に向かって漸次縮径してスリーブ部５２ａとの径方向間隙が漸次拡大するテーパ部に形成され、スリーブ部５２ａと軸部材２０の間の潤滑油の下端界面が表面張力によりこのテーパ部に保持されるよう構成されている。
【００３９】
回転スリーブ体５０は、このようにして、固定軸体１８に対し回転自在に支持されている。
【００４０】
スラスト軸受部８０における軸受隙間を適切なものとするために下スラスト部材５４の上面と上スラスト部材５６の下面の軸心方向間隔をスラスト鍔状部材２２の上下両面間の軸心方向寸法に対し適切なものとするには、下スラスト部材５４と上スラスト部材５６の間に挟まれたスペーサ部材５８の軸心方向寸法を適切なものとすれば良い。従って、スリーブ部材５２に関しては、ラジアル軸受部９０とスラスト軸受部８０の両方について同時に厳しい精度を要求されるのではなく、ラジアル軸受部９０に関するスリーブ部５２ａの内径寸法が軸部材２０の外径の寸法に対し適切であれば良いので、加工が容易である。
【００４１】
上スラスト部材５６の上側には、大内径部５２ｂの内周面に対し同軸状に、環状のキャップ部材６０が内嵌固定されている。キャップ部材６０の内下部には環状の切欠部が形成されて上スラスト部材５６の上面との間に内方開口の溝状部が構成されており、この溝状部により潤滑油滴の上方飛散が防止される。
【００４２】
ハードディスクが外嵌固定されるロータハブ６２は、略円筒形状をなし、その上部には全周にわたる内方膨出部６２ａを有し、下部には、全周にわたる外方張出部６２ｂを有する。ロータハブ６２における内方膨出部６２ａよりも下方の内周面には、円筒形状のロータヨーク６４が内嵌固定され、更にその内周面にロータマグネット６６が内嵌固定されている。このロータハブ６２の上部内周部がスリーブ部材５２の大内径部５２ｂに外嵌固定されることにより、回転スリーブ体５０とロータハブ６２とが同軸状に一体化されてロータを構成し、ロータマグネット６６がステータコア２６と径方向外方に相対して電動機を構成している。ロータハブ６２の外方張出部６２ｂの下部は、環状凹部１２内に位置している。
【００４３】
このスピンドルモータにおいては、ラジアル軸受部９０において、ブロンズ材製のスリーブ部材５２の内周面に比し、ステンレス鋼製の軸部材２０の外周面の方が硬く、スラスト軸受部８０において、ステンレス鋼製のスラスト鍔状部材２２の上下両面に比し、そのステンレス鋼よりも硬いステンレス鋼製の下スラスト部材５４及び上スラスト部材５６におけるそれぞれ上面及び下面の方が硬いので、ラジアル軸受部９０においてもスラスト軸受部８０においても焼付きが生じ難い。而も、スラスト鍔状部材２２における上下両面に比し、上下スラスト部材５４・５６の方が硬いので、上下スラスト部材５４・５６がスラスト鍔状部材２２の外周縁により損傷することや、上下スラスト部材５４・５６とスラスト鍔状部材２２との間の摩耗による回転精度の低下が効果的に防がれる。
【００４４】
図２は、本発明の別の滑り軸受装置を備えたスピンドルモータの実施の形態の一例としての、ハードディスク駆動用のスピンドルモータ（ブラシレスＤＣモータ）の断面図である。
【００４５】
このスピンドルモータでは、下スラスト部材１５４の外周側部に、上方突出の円環状のスペーサ部１５４ａを有し、スペーサ部材を有しない。スペーサ部１５４ａの内径はスラスト鍔状部材２２の外径よりもやや大きい。下スラスト部材１５４と上スラスト部材５６は、スペーサ部１５４ａの上面上に上スラスト部材５６の下面が当接して環状拡径面５２ｃ上に積み重なった状態で大内径部５２ｂの内周面に対し同軸状に内嵌固定されている。そして回転スリーブ体１５０の下スラスト部材１５４の内周側上面（第１スラスト支持部）と上スラスト部材５６の内周側下面（第２スラスト支持部）間にスラスト鍔状部材２２が挟まれてスラスト軸受部８０を構成する。
【００４６】
スラスト軸受部８０における軸受隙間を適切なものとするために下スラスト部材１５４の内周側上面と上スラスト部材５６の内周側下面の軸心方向間隔をスラスト鍔状部材２２の上下両面間の軸心方向寸法に対し適切なものとするには、スペーサ部１５４ａの上下方向寸法を適切なものとすれば良い。従って、スリーブ部材５２に関しては、ラジアル軸受部９０とスラスト軸受部１８０の両方について同時に厳しい精度を要求されるのではなく、ラジアル軸受部９０についてのスリーブ部５２ａの内径寸法が軸部材２０の外径の寸法に対し適切であれば良いので、加工が容易である。
【００４７】
また、ベースプレート１１０はロータハブ６２よりも外径が小さく、上方開口の環状凹部を有さない。更に、キャップ部材１６０は、その内周部に上方突出の円筒状部を有する。その他は図１のものと同様である。
【００４８】
【発明の効果】
本発明の軸受装置及び回転機械は、ラジアル軸受部においてもスラスト軸受部においても焼付きが生じ難く且つスラスト軸受部において損傷若しくは摩耗及びそれによる回転精度の低下が効果的に防がれる。
【００４９】
請求項２及び請求項３の軸受装置並びにその軸受装置を備えた回転機械は、スリーブ部の内径寸法とスラスト鍔状部に対する軸心方向の寸法を同時に満足することを必要とせず、スリーブ部材の加工が容易で全体として製造容易である。
【図面の簡単な説明】
【図１】滑り軸受装置を備えたスピンドルモータの断面図である。
【図２】別の滑り軸受装置を備えたスピンドルモータの断面図である。
【図３】従来の滑り軸受装置を備えたスピンドルモータの断面図である。
【符号の説明】
１０ベースプレート
１０ａ引出孔
１２環状凹部
１４ステータ支持部
１６嵌合孔
１８固定軸体
２０軸部材
２２スラスト鍔状部材
２２ａ循環路
２２ｂ連通用溝部
２４ステータコイル
２４ａ引出部
２６ステータコア
５０回転スリーブ体
５２スリーブ部材
５２ａスリーブ部
５２ｂ大内径部
５２ｃ環状拡径面
５４下スラスト部材
５６上スラスト部材
５８スペーサ部材
６０キャップ部材
６２ロータハブ
６２ａ内方膨出部
６２ｂ外方張出部
６４ロータヨーク
６６ロータマグネット
８０スラスト軸受部
９０ラジアル軸受部
１１０ベースプレート
１５０回転スリーブ体
１５４下スラスト部材
１５４ａスペーサ部
１６０キャップ部材
１８０スラスト軸受部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sliding bearing device including a radial bearing portion and a thrust bearing portion used for a spindle motor or the like used for driving a recording medium, and a rotary machine including the bearing device.
[0002]
[Prior art and problems to be solved by the invention]
As a bearing device such as a spindle motor used for driving a recording medium such as a high-capacity floppy disk, a magneto-optical disk, a CD-ROM, a DVD, or a hard disk, a sliding bearing device as shown in FIG. 3 is known. In this sliding bearing device, a rotating sleeve body d in a state of being externally fitted to a fixed shaft body c is fixed to a fixed shaft body c provided with an annular plate-like thrust collar portion b near the upper end of the shaft portion a. , And are supported so as to be able to rotate coaxially about their axis.
[0003]
The rotating sleeve body d includes a sleeve member e and an annular thrust support plate f. The sleeve member e is positioned adjacent to the sleeve portion e1, the medium inner diameter portion e2 which is positioned above the sleeve portion e1, and has an inner diameter larger than that of the sleeve portion e1, and the medium inner diameter portion e2. It consists of a large inner diameter part e3 whose inner diameter is larger than the inner diameter part e2. A boundary portion between the inner peripheral surface of the medium inner diameter portion e2 and the inner peripheral surface of the sleeve portion e1 is formed in an annular thrust support surface e4 perpendicular to the axial center line, and the inner peripheral surface of the inner inner diameter portion e2 and the large inner diameter portion e3. The boundary portion of the inner peripheral surface is formed in an annular surface e5 perpendicular to the axis. The thrust support plate f is fitted and fixed to the large inner diameter portion e3 in a state where the lower surface of the thrust support plate f is in contact with the annular surface e5.
[0004]
The sleeve portion e1 of the sleeve member e of the rotating sleeve body d is fitted into the shaft portion a of the fixed shaft body c, and the outer peripheral surface of the shaft portion a and the inner peripheral surface of the sleeve member e are in the radial direction. A radial sliding bearing portion is configured in an opposed state.
[0005]
The thrust collar portion b of the fixed shaft body c constitutes a thrust sliding bearing portion with the lower surface facing the thrust support surface e4 and the upper surface facing the lower surface of the thrust support plate f in the axial direction.
[0006]
In this conventional sliding bearing device, in order to prevent seizure between the fixed shaft body c and the rotating sleeve body d during use, each member of the rotating sleeve body d is relatively made of bronze material or the like. The members of the fixed shaft body c are made of a relatively hard material such as stainless steel. Therefore, in the thrust sliding bearing portion with a high peripheral speed, the thrust support surface e4 of the sleeve member e made of bronze material or the lower surface of the thrust support plate f is damaged by the stainless steel thrust flange portion b, When the perpendicularity of the thrust hook-shaped part b with respect to the body c is bad, it may be damaged by the outer peripheral edge of the thrust hook-shaped part b and may be damaged by the edge of the dynamic pressure groove provided in the thrust hook-shaped part b. Further, the thrust support surface e4 of the sleeve member e or the lower surface of the thrust support plate f is likely to be worn. Further, since the thrust support surface e4 of the sleeve member e made of bronze material is difficult to obtain roughness accuracy due to the construction method, it has minute irregularities and is easily worn by the thrust flange portion b.
[0007]
Further, in order to make the bearing clearances in the radial sliding bearing portion and the thrust sliding bearing portion appropriate, for the radial sliding bearing portion, the dimension of the inner diameter of the sleeve portion e1 in the sleeve member e is the shaft portion a of the fixed shaft body c. As for the thrust sliding bearing portion, the axial distance between the thrust support surface e4 and the lower surface of the thrust support plate f is the vertical axis of the thrust collar portion b of the fixed shaft c. What is necessary is just to be appropriate with respect to the axial direction dimension between both surfaces.
[0008]
However, in order to achieve an appropriate axial distance between the thrust support surface e4 and the lower surface of the thrust support plate f, the annular surface e5 and the thrust support surface e4 of the sleeve member e with which the lower surface of the thrust support plate f abuts. It is necessary to make the axial center interval appropriate for the axial center dimension between the upper and lower surfaces of the thrust flange b.
[0009]
That is, for the sleeve member e, the inner diameter dimension of the sleeve portion e1 and the axial center interval between the annular surface e5 and the thrust support surface e4 are the same as the outer diameter dimension of the shaft portion a and the shaft between the upper and lower surfaces of the thrust collar portion b. It is necessary to satisfy at the same time the dimensions in the center direction. For this reason, the accuracy required for processing the sleeve member e is severe, which has been a factor of increasing the manufacturing cost as a whole.
[0010]
The present invention has been made in view of the above-described problems existing in the prior art, and an object of the present invention is a sliding bearing device having a radial bearing portion and a thrust bearing portion, A bearing device that is difficult to seize both in the bearing portion and the thrust bearing portion, and that can effectively prevent damage or wear of the thrust bearing portion and a decrease in rotational accuracy caused thereby, and a rotary machine including the bearing device, and A bearing device that does not require the inner diameter dimension of the sleeve portion and the axial dimension relative to the thrust hook-shaped portion to be satisfied at the same time, and that can easily process the sleeve member as a whole, and a rotary machine equipped with the bearing device. It is to provide.
[0011]
[Means for Solving the Problems]
The bearing device of the present invention that achieves the above object is as follows.
A shaft body comprising a shaft portion and a thrust flange-like portion projecting radially outward from the shaft portion;
A sleeve portion, and a sleeve member that is located on one end side of the sleeve portion and has a large inner diameter portion that has an inner diameter larger than that of the sleeve portion;
A radial structure in which the sleeve portion is fitted into the shaft portion, a dynamic pressure groove is provided on at least one of the inner peripheral surface of the sleeve portion and the outer peripheral surface of the shaft portion, and lubricating oil is interposed between the both surfaces. A bearing device that constitutes a bearing portion, the thrust collar-like portion is located in the large inner diameter portion, and the shaft body and the sleeve member can be relatively rotated coaxially about their axial center lines,
A first thrust member and a second thrust member each having a first thrust support portion and a second thrust support portion facing in the axial direction are disposed in the large inner diameter portion, and they are fixed to the sleeve member,
The thrust trough-like portion is sandwiched between the first thrust member and the second thrust member, and the first thrust support portion, the second thrust support portion, and both axial direction surfaces of the thrust trough-like portion Between each of them, a thrust bearing portion is formed by having a dynamic pressure groove on the thrust flange-like portion side of each opposing surface and interposing lubricating oil between the opposing surfaces ,
Compared to the inner peripheral surface of the sleeve portion, both the outer peripheral surface of the shaft portion and the axial center both sides of the thrust collar-like portion are harder, and the first thrust than the both axial surfaces of the thrust collar-like portion The support portion and the second thrust support portion are harder (Claim 1).
[0012]
The outer peripheral surface of the shaft portion is harder than the inner peripheral surface of the sleeve portion, and the first thrust support portion and the second thrust support portion are harder than both axial direction surfaces of the thrust hook-shaped portion. Seizure hardly occurs even between the shaft portion and the shaft portion, and also between the first thrust support portion and the second thrust support portion and the thrust collar portion. In addition, since the first thrust support portion and the second thrust support portion are harder than the both sides in the axial direction of the thrust collar portion, the first thrust support portion or the second thrust support portion is It is possible to effectively prevent damage due to the outer peripheral edge and a decrease in rotational accuracy due to wear between the first thrust member and the second thrust member and the thrust collar.
[0013]
The shaft portion of the shaft body and the thrust hook-shaped portion may be a combination of separate members, or may be a single body. As for the shape of the shaft body, for example, the shaft portion can be formed into a substantially cylindrical shape, and the thrust collar portion can be formed into an annular plate shape. The position of the thrust hook-shaped portion in the shaft body can be near one end portion of the shaft portion.
[0014]
In a radial bearing portion configured by fitting a sleeve portion of a sleeve member into a shaft portion of a shaft body, the inner peripheral surface of the sleeve portion and the outer peripheral surface of the shaft portion are opposed to each other in the radial direction via a lubricant. As the lubricant, for example, lubricating oil such as spindle oil can be appropriately selected and used.
[0015]
The first thrust support portion and the second thrust in the first thrust member and the second thrust member, which are located in one end side of the sleeve portion in the sleeve member and are disposed in the large inner diameter portion whose inner diameter is larger than that of the sleeve portion. A thrust collar portion is sandwiched between the support portions to constitute a thrust bearing portion. In other words, both axial surfaces of the thrust rod-shaped portion are opposed to the first thrust support portion and the second thrust support portion via the lubricant as described above. In this thrust bearing portion, for example, the first thrust support portion and the second thrust support portion each have an annular surface shape, and both axial first surfaces of the first thrust support portion, the second thrust support portion, and the thrust collar portion Of these, the portions constituting the thrust bearing portion relative to the first thrust support portion and the second thrust support portion may each be perpendicular to the axial direction.
[0016]
For example, the inner peripheral surface of the large inner diameter portion may have a cylindrical surface shape that is coaxial with the sleeve portion. Moreover, the boundary part of the internal peripheral surface of a large internal diameter part and the internal peripheral surface of a sleeve part can be comprised in the annular surface shape perpendicular | vertical with respect to an axial direction, for example.
[0017]
The shape of the first thrust member and the second thrust member can be, for example, an annular plate shape.
The shaft body, and the sleeve body formed by fixing the first thrust member and the second thrust member to the sleeve member can relatively rotate coaxially about their axis. This bearing device can be configured such that the shaft body is fixed and the sleeve body side rotates, and the sleeve body side is fixed and the shaft body rotates.
[0019]
The outer peripheral surface of the shaft portion and the axial center both surfaces of the thrust collar portion may be the same hardness or different hardness. The axial center both surfaces in the thrust hook-shaped portion means both the upper and lower surfaces in the thrust hook-shaped portion if the axial direction is the vertical direction. In the normal case, the axially opposite surfaces of the thrust collar, and the first thrust support portion and the second thrust support portion have the same hardness in a normal case. For example, the inner peripheral surface of the sleeve portion is made of a bronze material, the outer peripheral surface of the shaft portion and both axial surfaces of the thrust hook-shaped portion are made of stainless steel, and the first thrust support portion is made of stainless steel harder than the stainless steel. A 2nd thrust support part shall be comprised.
[0020]
In the bearing device of the present invention, each of the sleeve member, the shaft portion, the thrust collar, the first thrust member, and the second thrust member has a constant hardness as a whole as well as a fixed surface, which is compared with the sleeve member. The shaft portion and the thrust hook-shaped portion are harder, and the first thrust member and the second thrust member can be harder than the thrust hook-shaped portion. In this case, since the shaft portion and the thrust collar portion are relatively hard, the shaft portion and the thrust collar portion are separate, and the thrust collar portion is fitted and fixed to the shaft portion by an interference fit. The pull-out strength (fitting strength) between the shaft portion and the thrust hook-shaped portion during the operation is relatively high.
[0021]
In the bearing device according to the present invention, one of the first thrust member and the second thrust member protrudes toward the other thrust member radially outward from the thrust flange-shaped portion and contacts the thrust member. The distance between the first thrust support portion and the second thrust support portion in the axial direction can be determined by the dimension in the axial direction of the spacer portion (claim 2).
[0022]
In order to make the bearing clearances in the radial bearing portion and the thrust bearing portion appropriate, for the radial bearing portion, the inner diameter of the sleeve portion of the sleeve member should be appropriate for the outer diameter of the shaft portion of the shaft body. For the thrust bearing part, the axial distance between the first thrust support part and the second thrust support part should be appropriate for the axial dimension between the axially opposite surfaces of the thrust collar of the shaft body. It ’s fine. In order to achieve an appropriate axial distance between the first thrust support portion and the second thrust support portion, one of the first thrust member and the second thrust member provided in the large inner diameter portion of the sleeve member has a spacer. What is necessary is just to make the axial direction direction dimension of a part suitable. Therefore, as for the dimension of the sleeve member, it is sufficient that the inner diameter dimension of the sleeve portion is appropriate to the outer diameter dimension of the shaft portion, and the inner diameter dimension of the sleeve portion and the axial direction dimension with respect to the thrust collar are satisfied at the same time. There is no need to do. Therefore, the processing of the sleeve member is easy, and the manufacturing as a whole is easy.
[0023]
The spacer portion can be, for example, an annular protrusion, in particular, an annular protrusion having a rotationally symmetric shape around the axial center line, and the inner peripheral surface has a cylindrical surface shape coaxial with the axial center line. It can be an annular protrusion. For example, such an annular protrusion may protrude from one thrust member by a certain length in the axial direction with respect to a plane perpendicular to the axial direction, and abut against the other thrust member.
[0024]
In the bearing device of the present invention, a spacer member separate from the first thrust member and the second thrust member, which is radially outward from the thrust collar, is disposed, and the axial direction of the spacer member Both surfaces are in contact with the first thrust member and the second thrust member, respectively, and the axial distance between the first thrust support portion and the second thrust support portion is determined by the axial dimension of the spacer member. (Claim 3).
[0025]
Also in this case, in the same manner as described above, the first thrust member and the second thrust member located within the large inner diameter portion of the sleeve member may be used in order to make the axial center distance between the first thrust support portion and the second thrust support portion appropriate. What is necessary is just to make the axial direction dimension of the spacer member arrange | positioned between members appropriate. Therefore, regarding the dimensions of the sleeve member, it is sufficient that the inner diameter dimension of the sleeve portion is appropriate to the outer diameter dimension of the shaft portion, and the inner diameter size of the sleeve portion and the axial dimension with respect to the thrust collar portion are satisfied simultaneously. Therefore, the sleeve member can be easily processed and manufactured as a whole.
[0026]
The spacer member in this case is a separate member from the first thrust member and the second thrust member, and can be, for example, an annular member, in particular, an annular member having a rotationally symmetric shape about the axis. Moreover, it can be set as the cyclic | annular member whose inner peripheral surface makes a cylindrical surface shape coaxial with an axial center line. For example, such an annular member can be fitted and fixed to the large inner diameter portion in a state where both surfaces in the axial direction are in contact with the first thrust member and the second thrust member, respectively.
Linear expansion coefficient of the spacer member, in consideration of the temperature compensation, it is desirable to be larger than the coefficient of linear expansion of the thrust collar portion (claim 4).
[0027]
Rotary machine of the present invention may be those with a bearing device of the present invention (Claim 5).
[0028]
As an example of this rotating machine, there can be mentioned an electric motor such as a spindle motor which employs the bearing device of the present invention as a bearing device. However, it is not necessarily limited to this. Examples of the spindle motor include those used for rotationally driving a recording medium such as a high-capacity floppy disk, a magneto-optical disk, a CD-ROM, a DVD, and a hard disk.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0030]
FIG. 1 is a cross-sectional view of a spindle motor (brushless DC motor) for driving a hard disk as an example of an embodiment of a spindle motor provided with a sliding bearing device of the present invention.
[0031]
The base plate 10 includes an annular recess 12 having an upper opening, a stator support portion 14 that protrudes upward in a cylindrical shape on the inner peripheral side of the annular recess 12, and a fitting hole 16 at the center.
[0032]
The fixed shaft body 18 is configured such that an annular plate-shaped thrust rod-shaped member 22 is fitted and fixed to an upper portion of a columnar shaft member 20, and the lower end portion of the shaft member 20 is fitted into the fitting hole 16 with respect to the base plate 10. It is erected vertically upward by being fitted and fixed to. The shaft member 20 and the thrust trough member 22 are made of the same stainless steel.
[0033]
A stator core 26 around which the stator coil 24 is wound is fitted and fixed to the stator support portion 14, and an extraction portion 24 a of the stator coil 24 passes through the bottom portion of the base plate 10 and is sealed through an extraction hole 10 a that is sealed. It is pulled out downward.
[0034]
The rotary sleeve 50 includes a sleeve member 52 made of a bronze material, an annular plate-like lower thrust member 54 and an upper thrust member made of stainless steel harder than the stainless steel constituting the shaft member 20 and the thrust collar member 22. 56 and an annular spacer member 58. The shaft member 20 and the thrust collar member 22 are connected by shrink fitting, and are made of stainless steel harder than the bronze material, so that the pull-out strength is relatively high.
[0035]
The sleeve member 52 includes a sleeve portion 52a having a cylindrical surface shape with a constant inner diameter, and a large inner diameter portion 52b positioned adjacent to the upper end side of the sleeve portion 52a. The inner peripheral surface of the large inner diameter portion 52b has a cylindrical surface shape with a constant inner diameter that is coaxial with the inner peripheral surface of the sleeve portion 52a. A boundary portion between the inner peripheral surface of the large inner diameter portion 52b and the inner peripheral surface of the sleeve portion 52a is formed in an annular enlarged surface 52c perpendicular to the axial direction. As for the outer diameter of the sleeve member 52, the outer diameter of the large inner diameter portion 52b is larger than the outer diameter of the sleeve portion 52a, as is the case with the inner diameter.
[0036]
The lower thrust member 54, the spacer member 58, and the upper thrust member 56 are fitted and fixed coaxially to the inner peripheral surface of the large inner diameter portion 52b in a state of being stacked on the annular enlarged surface 52c in this order. The inner diameters of the lower thrust member 54 and the upper thrust member 56 are slightly larger than the outer diameter of the shaft member 20, and the inner diameter of the spacer member 58 is slightly larger than the outer diameter of the thrust collar member 22.
[0037]
The thrust collar member 22 is sandwiched between the lower thrust member 54 and the upper thrust member 56 of the rotating sleeve body 50 to constitute the thrust bearing portion 80. The lower and upper surfaces of the thrust trough member 22 have dynamic pressure generating grooves, respectively, and the upper surface (first thrust support portion) of the lower thrust member 54 and the lower surface (second thrust) of the upper thrust member 56 via lubricating oil. It is opposed to the support part) in the axial direction. Both the upper inner peripheral edge of the lower thrust member 54 and the lower inner peripheral edge of the upper thrust member 56 are formed as upper and lower taper portions in which the axial center gap with the thrust rod-shaped member 22 gradually increases inward in the radial direction. In addition, the inner interface of the lubricating oil between the thrust rod-shaped member 22, the lower thrust member 54, and the upper thrust member 56 is configured to be held in these tapered portions by surface tension. Further, a circulation path 22a through which the lubricating oil circulates is provided in the thrust bowl-like member 22 so that bubbles in the lubricating oil are opened to the gas side through the inner interface of the lubricating oil in these tapered portions. The circulation path opens to the outer peripheral surface of the thrust rod-shaped member 22 and the outer peripheral portion of the upper and lower tapered portions. In addition, a communication groove portion 22 b is provided on the inner peripheral portion of the thrust rod-shaped member 22 to form an upper and lower communication hole that communicates the inner peripheral side portion of the upper and lower taper portions with the outer peripheral surface of the shaft member 20.
[0038]
A sleeve portion 52 a is fitted into a portion of the shaft member 20 below the thrust flange-like member 22 and above the base plate 10 to form a radial bearing portion 90. The upper and lower portions of the outer peripheral surface of this portion of the shaft member 20 have dynamic pressure generating grooves, respectively, and are opposed to the inner peripheral surface of the sleeve portion 52a in the radial direction via the lubricating oil. The outer diameter of the portion of the shaft member 20 between both dynamic pressure generating grooves is slightly reduced. The outer diameter of the portion of the shaft member 20 that faces the lower end of the sleeve portion 52a is formed into a tapered portion that gradually decreases in diameter downward and the radial gap with the sleeve portion 52a gradually increases. The lower end interface of the lubricating oil between the shaft member 20 and the shaft member 20 is held by the taper portion by surface tension.
[0039]
In this way, the rotating sleeve body 50 is rotatably supported with respect to the fixed shaft body 18.
[0040]
In order to make the bearing clearance in the thrust bearing portion 80 appropriate, the axial center interval between the upper surface of the lower thrust member 54 and the lower surface of the upper thrust member 56 is set with respect to the axial direction dimension between the upper and lower surfaces of the thrust collar member 22. In order to make it appropriate, the axial direction dimension of the spacer member 58 sandwiched between the lower thrust member 54 and the upper thrust member 56 may be made appropriate. Accordingly, the sleeve member 52 is not required to have strict accuracy at the same time for both the radial bearing portion 90 and the thrust bearing portion 80, but the inner diameter dimension of the sleeve portion 52a with respect to the radial bearing portion 90 is equal to the outer diameter of the shaft member 20. As long as it is appropriate for the dimensions, processing is easy.
[0041]
On the upper side of the upper thrust member 56, an annular cap member 60 is fitted and fixed coaxially with the inner peripheral surface of the large inner diameter portion 52b. An annular notch is formed in the inner lower portion of the cap member 60 to form an inwardly-opening groove-like portion between the upper surface of the upper thrust member 56, and this groove-like portion scatters the lubricating oil droplets upward. Is prevented.
[0042]
The rotor hub 62 on which the hard disk is fitted and fixed has a substantially cylindrical shape, and has an inwardly bulging portion 62a over the entire circumference at the top and an outwardly extending portion 62b over the entire circumference at the bottom. A cylindrical rotor yoke 64 is fitted and fixed to the inner peripheral surface of the rotor hub 62 below the inwardly bulging portion 62a, and a rotor magnet 66 is fixed to the inner peripheral surface. When the upper inner peripheral portion of the rotor hub 62 is externally fitted and fixed to the large inner diameter portion 52b of the sleeve member 52, the rotating sleeve body 50 and the rotor hub 62 are coaxially integrated to form a rotor, and the rotor magnet 66 Constitutes an electric motor facing the stator core 26 radially outward. The lower part of the outwardly projecting portion 62 b of the rotor hub 62 is located in the annular recess 12.
[0043]
In this spindle motor, the outer peripheral surface of the shaft member 20 made of stainless steel is harder in the radial bearing portion 90 than the inner peripheral surface of the sleeve member 52 made of bronze material. The upper and lower surfaces of the lower thrust member 54 and the upper thrust member 56 made of stainless steel, which are harder than the stainless steel, are harder than the upper and lower surfaces of the thrust saddle-shaped member 22 made of steel. The thrust bearing portion 80 is also less likely to seize. Since the upper and lower thrust members 54 and 56 are harder than the upper and lower surfaces of the thrust collar member 22, the upper and lower thrust members 54 and 56 are damaged by the outer peripheral edge of the thrust collar member 22, and the upper and lower thrust members A reduction in rotational accuracy due to wear between the members 54 and 56 and the thrust collar member 22 is effectively prevented.
[0044]
FIG. 2 is a cross-sectional view of a spindle motor (brushless DC motor) for driving a hard disk as an example of an embodiment of a spindle motor provided with another slide bearing device of the present invention.
[0045]
This spindle motor has an annular protruding spacer portion 154a on the outer peripheral side portion of the lower thrust member 154, and does not have a spacer member. The inner diameter of the spacer portion 154 a is slightly larger than the outer diameter of the thrust collar member 22. The lower thrust member 154 and the upper thrust member 56 are coaxial with the inner peripheral surface of the large inner diameter portion 52b in a state where the lower surface of the upper thrust member 56 abuts on the upper surface of the spacer portion 154a and is stacked on the annular enlarged surface 52c. The inner fitting is fixed. Then, the thrust collar member 22 is sandwiched between the upper surface on the inner peripheral side (first thrust support portion) of the lower thrust member 154 of the rotating sleeve body 150 and the lower surface on the inner peripheral side (second thrust support portion) of the upper thrust member 56. A thrust bearing portion 80 is configured.
[0046]
In order to provide an appropriate bearing clearance in the thrust bearing portion 80, the axial center interval between the inner peripheral upper surface of the lower thrust member 154 and the inner peripheral lower surface of the upper thrust member 56 is set between the upper and lower surfaces of the thrust collar member 22. In order to make the dimension appropriate for the axial direction dimension, the vertical dimension of the spacer portion 154a may be made appropriate. Accordingly, the sleeve member 52 is not required to have strict accuracy at the same time for both the radial bearing portion 90 and the thrust bearing portion 180, but the inner diameter dimension of the sleeve portion 52 a for the radial bearing portion 90 is the outer diameter of the shaft member 20. Since it is sufficient if it is appropriate for the dimensions, the processing is easy.
[0047]
Further, the base plate 110 has an outer diameter smaller than that of the rotor hub 62 and does not have an annular recess having an upper opening. Further, the cap member 160 has a cylindrical portion protruding upward on the inner peripheral portion thereof. Others are the same as those of FIG.
[0048]
【The invention's effect】
In the bearing device and the rotating machine of the present invention, seizure hardly occurs in the radial bearing portion and the thrust bearing portion, and damage or wear in the thrust bearing portion and a decrease in rotational accuracy due to this are effectively prevented.
[0049]
The bearing device according to claim 2 and claim 3 and the rotary machine provided with the bearing device do not need to satisfy the inner diameter dimension of the sleeve portion and the dimension in the axial direction with respect to the thrust hook-shaped portion at the same time. Processing is easy and manufacturing is easy as a whole.
[Brief description of the drawings]
FIG. 1 is a sectional view of a spindle motor provided with a sliding bearing device.
FIG. 2 is a sectional view of a spindle motor provided with another slide bearing device.
FIG. 3 is a cross-sectional view of a spindle motor provided with a conventional plain bearing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Base plate 10a Pull-out hole 12 Annular recessed part 14 Stator support part 16 Fitting hole 18 Fixed shaft body 20 Shaft member 22 Thrust hook-shaped member 22a Circulation path 22b Groove part 24 Stator coil 24a Lead-out part 26 Stator core 50 Rotating sleeve body 52 Sleeve member 52a Sleeve portion 52b Large inner diameter portion 52c Annular enlarged surface 54 Lower thrust member 56 Upper thrust member 58 Spacer member 60 Cap member 62 Rotor hub 62a Inwardly bulging portion 62b Outwardly projecting portion 64 Rotor yoke 66 Rotor magnet 80 Thrust bearing portion 90 Radial bearing portion 110 Base plate 150 Rotating sleeve body 154 Lower thrust member 154a Spacer portion 160 Cap member 180 Thrust bearing portion

Claims

A shaft body comprising a shaft portion and a thrust flange-like portion projecting radially outward from the shaft portion;
A sleeve portion, and a sleeve member that is located on one end side of the sleeve portion and has a large inner diameter portion that has an inner diameter larger than that of the sleeve portion;
A radial structure in which the sleeve portion is fitted into the shaft portion, a dynamic pressure groove is provided on at least one of the inner peripheral surface of the sleeve portion and the outer peripheral surface of the shaft portion, and lubricating oil is interposed between the both surfaces. A bearing device that constitutes a bearing portion, the thrust collar-like portion is located in the large inner diameter portion, and the shaft body and the sleeve member can be relatively rotated coaxially about their axial center lines,
A first thrust member and a second thrust member each having a first thrust support portion and a second thrust support portion facing in the axial direction are disposed in the large inner diameter portion, and they are fixed to the sleeve member,
The thrust trough-like portion is sandwiched between the first thrust member and the second thrust member, and the first thrust support portion, the second thrust support portion, and both axial direction surfaces of the thrust trough-like portion Between each of them, a thrust bearing portion is formed by having a dynamic pressure groove on the thrust flange-like portion side of each opposing surface and interposing lubricating oil between the opposing surfaces,
Compared to the inner peripheral surface of the sleeve portion, both the outer peripheral surface of the shaft portion and the axial center both sides of the thrust collar-like portion are harder, and the first thrust than the both axial surfaces of the thrust collar-like portion A bearing device characterized in that the support portion and the second thrust support portion are harder.

One of the first thrust member or the second thrust member has a spacer portion that protrudes toward the other thrust member and is in contact with the thrust member, radially outward from the thrust flange-shaped portion. 2. The bearing device according to claim 1, wherein the axial distance between the first thrust support portion and the second thrust support portion is determined by the dimension in the axial direction.

Separate spacer members are disposed between the first thrust member and the second thrust member radially outward from the thrust collar, and both surfaces of the spacer member in the axial direction are first. The bearing device according to claim 1, wherein the bearing is in contact with the thrust member and the second thrust member, and the axial distance between the first thrust support portion and the second thrust support portion is determined by the axial dimension of the spacer member. .

The bearing device according to claim 3, wherein the linear expansion coefficient of the spacer member is larger than the linear expansion coefficient of the thrust bowl-shaped portion.

A rotating machine comprising the bearing device according to claim 1, 2, 3 or 4.