JP3987331B2

JP3987331B2 - Oil-impregnated bearing

Info

Publication number: JP3987331B2
Application number: JP2001367182A
Authority: JP
Inventors: 猛田中; 徹伊藤
Original assignee: Asmo Co Ltd
Current assignee: Asmo Co Ltd
Priority date: 2001-11-30
Filing date: 2001-11-30
Publication date: 2007-10-10
Anticipated expiration: 2021-11-30
Also published as: JP2003166536A

Description

【０００１】
【発明の属する技術分野】
本発明は、その内部に潤滑油を含浸させた多孔質状の含油軸受に関するものである。
【０００２】
【従来の技術】
従来、車両用空調装置の電動機（具体的には、ブロワモータ）において、回転軸を支持するために含油軸受が用いられている。含油軸受は、潤滑油を含ませた多孔質状の焼結合金により形成され、回転軸が回転する含油軸受の内周面は円筒状になっている。モータの起動時において、回転軸は含油軸受の内周面に対して摺動するようになっている。一般的なブロワモータは、回転軸が略鉛直方向に沿って配置され、空調装置の駆動源として使用されている。このような構成では、モータの停止後、長時間経過すると含油軸受に含浸されている潤滑油は、含油軸受の内周面と回転軸との間の隙を伝わり外部に流出していた。また、含油軸受の内周面の表面には多数の空孔が存在しており、その空孔の内部に潤滑油が吸い込まれていた。このような理由から、含油軸受の内周面において、回転軸との摺動に用いられるべく潤滑油が減少してしまうという問題があった。特に、雰囲気温度が氷点下前後にまで下がった状態においては、潤滑油が含油軸受の内周面にほとんど残存しないことがあった。この場合、モータを起動させると、含油軸受と回転軸との摩擦抵抗が大きくなってしまう。また、回転軸が含油軸受の内周面と摺動しながら回転する際、潤滑油による制振効果を得ることができなかった。そのため、モータの起動時に、不快な音（異音）が発生することがあった。
【０００３】
そこで、上記した問題点の第１の解決策として特開２０００−３４６０７４号公報で開示された技術がある。この公報の技術では、含油軸受の内周面の一部に円筒状に非多孔質状表面を設けた含浸軸受を提案している。具体的には、図７に示すように、含油軸受６０は、中央軸受部６１と、その中央軸受部の上方に設けられた上端軸受部６２と、その中央軸受部の下方に設けられた下端軸受部６３とからなる。上端軸受部６２の内周面の径は、上端に向かうほど徐々に大きくなっている。また、下端軸受部６３の内周面の径は、下端に向かうほど徐々に大きくなっている。この場合、中央軸受部６１と下端軸受部６３との境界部近傍には、非多孔質状表面６４が形成されている。そして、モータ停止後、長時間経過しても非多孔質状表面６４に潤滑油を残存させるようになっている。
【０００４】
【発明が解決しようとする課題】
しかしながら、モータ停止後、長時間経過すると雰囲気温度が下がる。すると、多孔質状表面の潤滑油は、熱収縮や毛細管現象等により多孔質状表面の空孔内に吸収される。この場合に、多孔質状表面と非多孔質状表面６４との境界部は滑らかに連続した平面状であるため、多孔質状表面の潤滑油は、非多孔質状表面６４の潤滑油と、互いに繋がっていることが多かった。このため、非多孔質状表面６４の潤滑油は、空孔内に吸収される多孔質状表面の潤滑油とともに、該空孔内に吸収されていた。その結果、非多孔質状表面の潤滑油が枯渇し、モータの起動時に不快な音（異音）が発生するという問題が生じていた。
【０００５】
本発明は、上記問題点を解決するためになされたものである。その目的は、電動機の停止後、長時間経過しても回転軸と含油軸受との摺動面に潤滑油を残存させて、電動機の起動時における異音を防止することができる含油軸受を提供することである。
【０００６】
【課題を解決するための手段】
上記の課題を解決するために、請求項１に記載の発明では回転軸が略鉛直方向に沿って配置される電動機に適用され、多数の空孔を有する多孔質材に潤滑油をしみ込ませてなる含油軸受であって、内周面が回転軸と平行になるように設けられ、その表面が多孔質状である第１軸受部と、軸受における前記回転軸の軸方向の中央であって前記第１軸受部の下方に設けられ、内周面の径が前記第１軸受部の内周面の径とほぼ等しく、その表面が非多孔質状である第２軸受部と、前記第１軸受部と前記第２軸受部との間に設けられ、内周面の径が前記第２軸受部の内周面の径よりも大きく、その表面が多孔質状である第３軸受部と、前記第２軸受部の下方に設けられ、内周面の径が下端に向かって徐々に大きくなり、その表面が非多孔質状である第４軸受部と、前記第４軸受部の下方に設けられ、内周面の径が前記第４軸受部の内周面の径よりも大きく、その表面が多孔質状である第５軸受部とを備え、前記第２軸受部と前記第３軸受部との境界部には第１段差部、前記第４軸受部と前記第５軸受部との境界部には第２段差部がそれぞれ設けられ、多孔質状の内周面の表面にしみ出た潤滑油の最小油膜厚さをｘ、最大油膜厚さをｙとし、前記第２軸受部の内周面に対する前記第３軸受部の内周面の段差をａ、前記第４軸受部の内周面に対する前記第５軸受部の内周面の段差をｂとしたとき、前記第１段差部及び前記第２段差部を、ａ＜ｘかつｙ＜ｂの関係を有するように形成したことをその要旨とする。
【０００８】
請求項２に記載の発明では、請求項１に記載の発明において、前記第１軸受部の下端部側の内周面の径は下方に向かうほど徐々に大きくなることをその要旨とする。
【０００９】
請求項３に記載の発明では、請求項１または２に記載の発明において、前記第５軸受部の内周面の径は下方に向かうほど徐々に大きくなることをその要旨とする。
【００１０】
請求項４に記載の発明では、請求項１乃至３のいずれか一項に記載の発明において、前記第２軸受部の内周面に対する前記第３軸受部の内周面の段差をａ、第３軸受部の略鉛直方向における長さをｚとしたとき、ｚ／ａは５〜５０であることをその要旨とする。
【００１１】
以下、本発明の「作用」について説明する。
請求項１に記載の発明によると、第２軸受部と第３軸受部との境界部には第１段差部、第４軸受部と第５軸受部との境界部には第２段差部がそれぞれ設けられている。この場合、回転軸の回転中に、第１軸受部の内周面からしみ出た潤滑油は、第１段差部を乗り越えて第２軸受部の内周面に移動する。しかし、一旦第２軸受部の内周面に移動した潤滑油は、内周面の径が第４軸受部と第５軸受部との境界部で急変しているため、第２段差部を乗り越えて第５軸受部の内周面に至ることはない。このため、内周面の表面が非多孔質状である第２軸受部及び第４軸受部に潤滑油を保持することができる。よって、電動機の停止後、長時間経過しても、第２軸受部及び第４軸受部の内周面に保持された潤滑油の量が減少することはない。それに加え、第１軸受部の内周面の径は第２軸受部の内周面の径とほぼ等しいため、回転軸は含油軸受の内周面に対してより大きい面積で摺接することができる。このため、回転軸は含油軸受の中心軸の位置に確実に保持されるため、回転軸と含浸軸受の内周面との干渉は抑制される。従って、電動機の起動時における異音の発生を防止することができる。
【００１２】
また、第２軸受部の内周面に対する第３軸受部の内周面の段差ａを、多孔質状表面にしみ出た潤滑油の最小油膜厚さｘよりも小さくした（ａ＜ｘ）。この場合、第１軸受部の内周面にしみ出た潤滑油は、第１段差部を乗り越えて第２軸受部の内周面に移動する。また、第４軸受部の内周面に対する第５軸受部の内周面の段差ｂを潤滑油の最大油膜厚さｙよりも大きくした（ｙ＜ｂ）。この場合、第４軸受部の内周面に移動した潤滑油は、第２段差部を乗り越えて第５軸受部の内周面に至ることない。つまり、内周面の表面が非多孔質状である第２軸受部及び第４軸受部に潤滑油を確実に保持することができる。よって、電動機の停止後、長時間経過しても、第２軸受部及び第４軸受部の内周面に保持された潤滑油の量が減少することはない。従って、電動機の起動時における異音の発生をより確実に防止することができる。
【００１３】
請求項２に記載の発明によると、第１軸受部の下端部側の内周面の径は下方に向かうほど徐々に大きくなる。この場合、第１軸受部の内周面の下端部側において、内周面と回転軸とのクリアランスが大きくなる。このため、第１軸受部の内周面からしみ出た潤滑油は回転軸に伝わることなく、第３軸受部の内周面に沿って第２軸受部の内周面に移動する。このような理由から、潤滑油は第１段差部を乗り越えて、第２軸受部の内周面に効率的に補充される。よって、内周面の表面が非多孔質状である第２軸受部及び第４軸受部における潤滑油の枯渇を防止することができる。従って、電動機の起動時における異音の発生をより確実に防止することができる。
【００１４】
請求項３に記載の発明によると、第５軸受部の内周面の径は下方に向かうほど徐々に大きくなる。この場合、第５軸受部の内周面の下端部に形成された角が小さくなる。よって、回転軸と含浸軸受の内周面との干渉が確実に抑制される。従って、電動機の起動時における異音の発生をよりいっそう防止することができる。
【００１５】
請求項４に記載の発明によると、第２軸受部の内周面に対する第３軸受部の内周面の段差をａとし、第３軸受部の略鉛直方向における長さをｚとしたときのｚ／ａの値は５〜５０である。このようにすれば、回転軸と第１軸受部の内周面とが摺接し合う面積を十分に確保することができる。このため、回転軸は、含油軸受の中心軸の位置により確実に保持される。よって、回転軸と含浸軸受の内周面との干渉がより確実に抑制される。従って、電動機の起動時における異音の発生をよりいっそう防止することができる。
【００１６】
【発明の実施の形態】
（第１実施形態）
以下、本発明をブロワモータ１に用いられる含油軸受９に具体化した第１実施形態を図１〜図３に従って説明する。
【００１７】
図１は本実施形態におけるブロワモータ１の断面図である。ブロワモータ１は、両端部に開口部を有する略円筒状のヨークハウジング２と、ヨークハウジング２の両端部を塞ぐように固定されるハウジングケース３，４とを備える。
【００１８】
ヨークハウジング２の内周側には、マグネット６がアーマチュア５を包囲するように配置されている。ハウジングケース３には、含油軸受７が固定され、その含油軸受７によってアーマチュア５から延びる回転軸８の基端部が回転可能に支持されている。一方、ハウジングケース４には含油軸受９が固定され、その含油軸受９によってアーマチュア５から延びる回転軸８が回転可能に支持されている。回転軸８の先端は、ハウジングケース４から外部に突出しており、その回転軸８の先端に図示しない送風ファンが固定されている。また、回転軸８においてアーマチュア５と含油軸受９との間の位置には、コンミテータ１０が配置されている。コンミテータ１０は、回転軸８と一体回転するように固定されている。さらに、コンミテータ１０の外周面に摺接するようにブラシ１１が配設されている。
【００１９】
ブロワモータ１は、回転軸８が鉛直方向に沿うように図示しない車両に固定されている。そして、モータ１の起動時において、図示しない外部電源からの直流電源がブラシ１１、コンミテータ１０等を経てアーマチュア５に供給されることにより、アーマチュア５が回転軸８とともに回転する。これによって、回転軸８の先端に固定した送風ファンによる送風動作が行われる。
【００２０】
次に、本実施形態における含油軸受７，９の構成について説明する。含油軸受７，９は、多数の空孔を有する多孔質焼結金属からなる。含油軸受７，９は、粉末金属を圧縮成形し、焼結、仕上げ加工され略円筒状に形成される。含油軸受７，９の表面及び内部には多数の連続気孔が存在している。図３（ａ）、図３（ｂ）に示す空孔４０は、含油軸受７，９の表面近傍における連続気孔の一部であり、その内部には潤滑油４５が含浸されている。潤滑油４５は、連続気孔及び空孔４０を通じて、含油軸受７，９の表面及び内部を自由に移動することができる。
【００２１】
図１における含油軸受９の拡大断面図を図２（ａ）、図２（ｂ）に示す。略円筒状の含油軸受９には、上端面及び下端面にて開口する貫通孔が設けられている。含油軸受９は、該貫通孔の内側面としての内周面１５を備えている。回転軸８は、含油軸受９の該貫通孔に挿入されており、モータ１の上端部と下端部とにおいて両支持されている。モータ１の起動時に、回転軸８は、含油軸受９の内周面１５と摺動するようになっている。
【００２２】
含油軸受９は、回転軸８の軸方向に垂直な平面により、複数の軸受部に分割される。図２（ａ）に示すように、含油軸受９の中央には第２軸受部２２が配置されている。第２軸受部２２の上方側には、第１軸受部２１と第３軸受部２３とが配置されている。また、第２軸受部２２の下方側には、第４軸受部２４と第５軸受部２５とが配置されている。さらに、含油軸受９の両端部には、テーパ部２６，２７がそれぞれ配置されている。
【００２３】
図２に示すように、第３軸受部２３は、第１軸受部２１と第２軸受部２２との間に配置されている。この場合、第１軸受部２１の内周面２１ａの径ｄ₀は、第２軸受部２２の内周面２２ａの径と等しく、また、第３軸受部２３の内周面２３ａの径ｄ₁は、第２軸受部２２の内周面２２ａの径ｄ₀よりも大きくなっている。このため、含油軸受９の内周面１５には、第３軸受部２３の内周面２３ａを底部とする溝部３５が円周方向に沿って環状に形成される。溝部３５は、第３軸受部２３の内周面２３ａと、第２軸受部２２の内側面２２ｂと、第１軸受部２１の内側面２１ｂとからなる。第２軸受部２２と第３軸受部２３との境界部には、第２軸受部２２の内周面２２ａと、第２軸受部２２の内側面２２ｂとからなる第１段差部３１が円周方向に沿って環状に形成されている。含油軸受９の内周面１５の径の大きさは、第１段差部３１において急変している。
【００２４】
第２軸受部２２の下方には第４軸受部２４が配置されている。第４軸受部２４の内周面２４ａの径は、上端部においてｄ₀であり、下端部においてｄ₂である。図２に示すように、第４軸受部２４の内周面２４ａの径は、上端部から下端部にかけて徐々に大きくなっている。また、第４軸受部２４の下方には、第５軸受部２５が配置されている。第５軸受部２５の内周面２５ａの径ｄ₃は、第４軸受部２４の内周面２４ａの径ｄ₂よりも大きくなっている。このため、第４軸受部２４と第５軸受部２５との境界部には、第４軸受部２４の内周面２４ａと、内側面２４ｂとからなる第２段差部３２が円周方向に沿って環状に形成されている。
【００２５】
第１軸受部２１の上方及び第５軸受部２５の下方にはテーパ部２６，２７が設けられている。テーパ部２６，２７の内周面２６ａ，２７ａの径は、含油軸受９の両端部に向かうほど徐々に大きくなっている。このようにすることで、回転軸８が含油軸受９の内周面１５の両端部に干渉することを防止している。
【００２６】
図２に示すように、テーパ部２６，２７、第１軸受部２１、第３軸受部２３及び第５軸受部２５は、その内周面２６ａ，２７ａ，２１ａ，２３ａ，２５ａが多孔質状表面になっている。第２軸受部２２及び第４軸受部２４は、その内周面２２ａ，２４ａが非多孔質状表面３４になっている。
【００２７】
次に、第１段差部３１及び第２段差部３２近傍の拡大図を、図３（ａ）、図３（ｂ）に示す。図３（ａ）、図３（ｂ）に示すように、多孔質状表面では、空孔４０の一端側が開口部になっている。このため、モータ１の停止後、雰囲気温度が下がると、潤滑油４５は、熱収縮や毛細管現象等により該開口部から空孔４０内に吸収される。一方、非多孔質状表面３４では、空孔４０の開口部が目潰しされている。このため、潤滑油４５は、非多孔質状表面３４から空孔４０内に吸収されない。
【００２８】
本実施形態において、第１段差部３１における段差ａ及び第２段差部３２における段差ｂは、多孔質状表面の潤滑油４５の油膜厚さに基づいて決定されている。具体的には、モータ１の起動時に、潤滑油４５の油膜厚さが１６μｍ〜２０μｍとなるように設定されている。この場合、段差ａは、潤滑油４５の最小油膜厚さｘよりも小さくなるように設定されている。これは、第１軸受部２１の内周面２１ａにしみ出た潤滑油４５が第１段差部３１を乗り越えて、第２軸受部２２の内周面２２ａに至るようにするためである。従って、第１段差部３１における段差ａは、５μｍ〜１５μｍに設定される。
【００２９】
また、第２段差部３２における段差ｂは、潤滑油４５の最大油膜厚さｙよりも大きくなるように設定されている。これは、第４軸受部２４の内周面２４ａの潤滑油４５が第２段差部３２を乗り越えて、第５軸受部２５の内周面２５ａに至ることがないようにするためである。従って、第２段差部３２における段差ｂは、３０μｍ以上に設定される。
【００３０】
ここで、段差ｂが非多孔質状表面の最大油膜厚さｙよりも大きく設定される理由を具体的に説明する。段差ｂが非多孔質状表面の最大油膜厚さｙよりも小さい場合、第４軸受部２４の内周面２４ａの潤滑油４５が第２段差部３２を乗り越えて第５軸受部２５の内周面２５ａの潤滑油４５と互いに繋がった状態になることがある。モータ１の停止後、雰囲気温度が下がると、第５軸受部２５の内周面２５ａの潤滑油４５が、熱収縮や毛細管現象などにより多孔質状表面の空孔４０内に吸収される。すると、非多孔質状表面３４の潤滑油４５は、多孔質状表面の潤滑油４５とともに、多孔質状表面の空孔４０内に吸収される。その結果、非多孔質状表面３４の潤滑油４５は枯渇する。このような理由から、第２段差部３２における段差ｂは、多孔質状表面の最大油膜厚さｙよりも大きく設定されることがより望ましい。
【００３１】
溝部３５の大きさは、第１段差部３１における段差ａと、第３軸受部２３の略鉛直方向における長さｚとにより決定されている。この場合、溝部３５は、ｚ／ａが５〜５０の関係を有するように形成される。本実施形態では、多孔質状表面の潤滑油４５の油膜厚さに基づいて、段差ａが５μｍ〜１５μｍに設定されている。このため、長さｚは１００μｍ〜２００μｍに設定されているのが最も望ましい。
【００３２】
次に、含油軸受９の製造方法の一例について説明する。まず、所定の型に原材料としての粉末金属が充填される。粉末金属は、貫通孔を形成するための芯材とともにプレス機等により圧縮成形される。圧縮成形後、芯材を成形体から抜き出すと、中央に貫通孔を備える略円筒状体の成形体が形成される。その後、圧縮成形体は焼成工程を経て多孔質焼結体になる。その結果、含油軸受９の本体の外側面及び貫通孔の内側面には多数の空孔が形成される。ここで、貫通孔の内側面の一部を非多孔質状表面３４にするために、多孔質状表面の空孔４０の開口部が、表面に凹凸を形成した芯材等を摺動させつつ抜き去ることにより部分的に目潰しされる。このようにして、非多孔質状表面３４は、貫通孔の内側面の一部に形成される。次に、含油軸受９の本体の内周面１５及び外周面を仕上げるための加工が行われる。このときに、内周面１５には、テーパ面２６ａ，２７ａ、溝部３５及び第２段差部３２等が形成される。そして、含油軸受９の本体に潤滑油４５を含浸させることにより、含油軸受９が作られる。
【００３３】
次に、回転軸８の回転時における潤滑油４５の動きを、図３（ａ）、図３（ｂ）に従って説明する。ブロワモータ１の起動に伴い回転軸８が回転すると、回転軸８は含油軸受９の内周面１５に摺接する。すると、含油軸受９の内周面１５は接触摩擦により発熱する。このため、内周面１５の表面近傍において、空孔４０内に吸収されていた潤滑油４５の体積が膨張する。そして、多孔質状表面の空孔４０内に充填されていた潤滑油４５は、空孔４０の開口部から外部へしみ出てくる。一方、非多孔質状表面３４においては、空孔４０の開口部が目潰しされているため、潤滑油４５がしみ出てくることはない。
【００３４】
第１軸受部２１の内周面２１ａからしみ出た潤滑油４５は、内周面２１ａ及び回転軸８の表面を伝って第３軸受部２３の内周面２３ａに至る。そして、潤滑油４５は、第１段差部３１を乗り越えて、第２軸受部２２の内周面２２ａに至る。
【００３５】
ブロワモータ１の停止に伴い回転軸８が静止すると、含油軸受９の雰囲気温度が下がる。すると、内周面１５にしみ出た潤滑油４５は、温度変化による熱収縮や毛細管現象等により、再び多孔質状表面の空孔４０内に吸収されていく。しかし、非多孔質状表面３４では、空孔４０の開口部が目潰しされているため、潤滑油４５が非多孔質状表面３４から空孔４０内に吸収されることはない。よって、第２軸受部２２及び第４軸受部２４の内周面２２ａ，２４ａには、潤滑油４５が空孔４０内に吸収されることなく、そのまま残存している。即ち、潤滑油４５は、高温時に多孔質状表面の空孔４０内から供給され、低温時に多孔質状表面の空孔４０内に回収される。
【００３６】
従って、この第１実施形態によれば、以下のような特徴を得ることができる。
（１）第２軸受部２２と第３軸受部２３との境界部には第１段差部３１、第４軸受部２４と第５軸受部２５との境界部には第２段差部３２がそれぞれ設けられている。この場合、内周面１５の径の大きさは、第２段差部３２において急変している。このため、モータ１の停止後、長時間経過しても、第２軸受部２２及び第４軸受部２４の内周面２２ａ，２４ａに潤滑油４５を保持することができる。それに加え、第１軸受部２１の内周面２１ａの径は、第２軸受部２２の内周面２２ａの径とほぼ等しい。このため、回転軸８は含油軸受９の内周面１５に対してより大きい面積で摺接することができる。よって、回転軸８は含油軸受９の中心軸の位置に確実に保持される。従って、回転軸８と含油軸受９の内周面１５との干渉は抑制されるとともに、モータ１の起動時における異音の発生を防止することができる。
【００３７】
（２）第２軸受部２２の内周面２２ａに対する第３軸受部２３の内周面２３ａの段差ａを、多孔質状表面にしみ出た潤滑油４５の最小油膜厚さｘよりも小さくした（ａ＜ｘ）。この場合、第１軸受部２１の内周面２１ａにしみ出た潤滑油４５は、第１段差部３１を乗り越えて第２軸受部２２の内周面２２ａに移動する。また、第４軸受部２４の内周面２４ａに対する第５軸受部２５の内周面２５ａの段差ｂを潤滑油４５の最大油膜厚さｙよりも大きくした（ｙ＜ｂ）。この場合、第４軸受部２４の内周面２４ａに移動した潤滑油４５は、第２段差部３２を乗り越えて第５軸受部２５の内周面２５ａに至ることない。つまり、第２軸受部２２及び第４軸受部２４内周面２２ａ，２４ａの多孔質状表面に潤滑油４５を確実に保持することができる。よって、モータ１の停止後、長時間経過しても、第２軸受部２２及び第４軸受部２４の内周面２２ａ，２４ａに保持された潤滑油４５の量が減少することはない。従ってモータ１の起動時における異音の発生をより確実に防止することができる。
【００３８】
（３）第２軸受部２２の内周面２２ａに対する第３軸受部２３の内周面２３ａの段差をａとし、第３軸受部２３の略鉛直方向における長さをｚとしたときのｚ／ａの値は５〜５０である。このようにすれば、回転軸８と第１軸受部２１の内周面２１ａとが摺接し合う面積を十分に確保することができる。このため、回転軸８は、含油軸受９の中心軸の位置により確実に保持される。よって、回転軸８と含油軸受９の内周面１５との干渉がより確実に抑制される。従って、モータ１の起動時における異音の発生をよりいっそう防止することができる。
（第２実施形態）
次に、本発明を具体化しブロワモータ１に使用される含油軸受９の第２実施形態を図４（ａ）、図４（ｂ）、図４（ｃ）に従って説明する。なお、第２実施形態において、第１実施形態と同様の部分においては、その詳細な説明を省略する。
【００３９】
本実施形態では、図４（ａ），図４（ｃ）に示すように、第１軸受部５１の下端部において、内周面５１ａの径が下方に向かうほど徐々に大きくなっている。このため、第１軸受部５１の内周面５１ａの下端部側には、テーパ面５１ｃが円周方向に沿って円環状に形成される。この場合、内周面５１ａと回転軸８とのクリアランスは、内周面５１ａの下端部にテーパ面５１ｃが形成されない場合に比べ大きくなる。また、第１軸受部５１の内周面５１ａと内側面５１ｂとからなる角部がなくなるため、第１軸受部５１の内周面５１ａにしみ出た潤滑油４５が回転軸８に伝わりにくくなる。このため、潤滑油４５は、第３軸受部５３の内周面５３ａに沿って移動し、第１段差部３１を乗り越えた後に第２軸受部５２の内周面５２ａに至る。この場合、第１軸受部５１の内周面５１ａの径が変化する位置６６は、第１軸受部５１の上端部と下端部との中間位置よりも下方側に設けられるのが望ましい。これは、回転軸８と含油軸受９の内周面１５との摺接面積を減らさないためである。
【００４０】
また、図４（ａ）、図４（ｂ）に示すように、第５軸受部５５の内周面５５ａの径は、上端部においてｄ₃であり、下端部においてｄ₄である。第５軸受部５５の内周面５５ａは、上端部から下端部にかけて下方に向かうほど徐々に大きくなっている。このようにすることで、モータ１の起動時に、回転軸８が含油軸受９の内周面１５の両端部と干渉することをより確実に防止することができる。
【００４１】
従って、この第２実施形態によれば、第１実施形態の効果に加え、以下のような効果を得ることができる。
（１）第１軸受部５１の下端部側の内周面５１ａの径は下方に向かうほど徐々に大きくなる。このため、第１軸受部５１の内周面５１ａからしみ出た潤滑油４５は、第１段差部３１を乗り越えて、第２軸受部５２の内周面５２ａに効率的に補充される。よって、内周面５２ａの表面が非多孔質状である第２軸受部５２及び第４軸受部５４における潤滑油４５の枯渇を防止することができる。従って、モータ１の起動時における異音の発生をより確実に防止することができる。
【００４２】
（２）第５軸受部５５の内周面５５ａの径は下方に向かうほど徐々に大きくなる。この場合、第５軸受部５５の内周面５５ａとテーパ部５７の内周面５７ａとからなる角部が小さくなる。よって、回転軸８と含油軸受９の内周面１５との干渉が確実に抑制される。従って、モータ１の起動時における異音の発生をよりいっそう防止することができる。
【００４３】
なお、前記実施形態は以下のように変更してもよい。
・前記実施形態では、含油軸受９の本体は、多孔質状の焼結合金により形成されていた。具体的には、炭素鋼、ニッケル合金、銅合金、アルミニウム合金等の粉末を圧縮成形し、焼成、仕上げ加工することにより形成されていた。しかし、含油軸受９の本体は、鉄、ニッケル、銅、アルミニウム等のような純金属の粉末を材料として形成されても良い。
【００４４】
・前記実施形態では、含油軸受９の本体は、多孔質の焼結合金により形成されていた。しかし、含油軸受９は、多孔質状の無機焼結体で形成されても良い。具体的には、炭化珪素、窒化アルミニウム、窒化珪素、アルミナ、ムライト、ジルコニア、グラファイト等が挙げられる。
【００４５】
・前記実施形態では、含油軸受９は、車両空調装置の電動機の回転軸８の支持に用いられていた。しかし、含油軸受９は、電動機の回転軸８以外の軸の支持に用いられても良い。
【００４６】
・前記実施形態では、図６（ａ）に示すように、含油軸受９の内周面１５の第３軸受部２３の位置に形成された溝部３５は、断面略四角状の凹部であった。しかし、溝部３５の形状は、図６（ｂ）、図６（ｃ）に示すように、断面略三角状の凹部や断面略円弧状の凹部であっても良い。
【００４７】
・前記実施形態では、第１段差部３１，第２段差部３２における角θ₁，角θ₂の形状は、直角または鈍角であった。しかし、第１段差部３１，第２段差部３２の角θ₁，角θ₂の形状は、これに限るものではなく、角を面取りした形状（ｃ面）や曲面状にした形状（Ｒ面）であっても良い。
【００４８】
・前記実施形態は、内周面１５には、１つの溝部３５が第３軸受部２３の内周面２３ａの位置に形成されていた。しかし、図５（ａ）、図５（ｂ）に示すように、内周面１５には、溝部３５以外にも他の溝部３６を形成しても良い。この場合、第６軸受部２８が第４軸受部２４と第５軸受部２５との間に配置されている。内周面２６ａの径は、第４軸受部２４の径よりも大きくなっている。このため、含油軸受９の内周面１５には、第６軸受部２８の内周面２６ａと第４軸受部２４の内側面２４ｂと第５軸受部２５の内側面２５ｂとからなる溝部３６が形成される。第４軸受部２４と第６軸受部２８との境界部には、第２段差部３２が形成される。第２段差部３２における段差ｂは、多孔質状表面にしみ出た潤滑油４５の最大油膜厚さをｙとした場合、ｙ＜ｂの関係を有するように形成されている。
【００４９】
・前記実施形態では、第２軸受部２２の内周面２２ａに対する第３軸受部２３の内周面２３ａの段差ａを５μｍ〜１５μｍとし、第４軸受部２４の内周面２４ａに対する第５軸受部２５の内周面２５ａの段差ｂを３０μｍ以上としたがこれに限るものではない。つまり、段差ａ＜最小油膜厚さｘ、段差ｂ＞最大油膜厚さｙの関係を有するものであれば良く、これらの段差ａ，ｂは、潤滑油４５の種類などに応じて適宜変更できる。但し、段差ａは、第１軸受部２１及び第２軸受部２２の内周面２１ａ，２２ａと回転軸８との間におけるクリアランスの範囲内で設定することが望ましい。
【００５０】
次に、上記実施形態及び別例から把握できる技術的思想を以下に記載する。
（１）前記含油軸受を備えたことを特徴とするモータ。このようにすれば、電動機の停止後、長時間経過しても、含油軸受の内周面の潤滑油を減少させることなく、電動機に起動時における異音を抑制することができるモータを提供することができる。
【００５１】
【発明の効果】
以上詳述したように、各請求項に記載の発明によれば電動機の停止後、雰囲気温度が下がった場合においても、回転軸と含油軸受との摺動面に潤滑油を残存させて、電動機に起動時における異音の発生を防止することができる含油軸受を提供することができる。
【００５２】
請求項２に記載の発明によれば、多孔質状の表面からしみ出た潤滑油が非多孔質状の表面に効率的に補充されるため、電動機に起動中における異音の発生を防止することができる。
【００５３】
請求項３または４に記載の発明によれば、回転軸と含浸軸受の内周面との干渉は抑制されるため、電動機の起動時における異音の発生をよりいっそう防止することができる。
【図面の簡単な説明】
【図１】本実施形態におけるブロワモータの概略構成を示す断面図。
【図２】（ａ）は本実施形態を示す含油軸受を示す断面図、（ｂ）は第１段差部及び第２段差部近傍の拡大断面図。
【図３】（ａ）はモータ回転時における潤滑油の動きを示す説明図、（ｂ）はモータ停止時における潤滑油の動きを示す説明図。
【図４】（ａ）は第２実施形態における含油軸受を示す断面図、（ｂ）は第５軸受部近傍の拡大断面図、（ｃ）は第１段差部近傍の拡大断面図。
【図５】（ａ）は別例の実施形態における含油軸受を示す断面図、（ｂ）は第１段差部及び第２段差部近傍の拡大断面図。
【図６】（ａ）本実施形態における溝部の拡大断面図、（ｂ）別例の実施形態における溝部の拡大断面図、（ｃ）別例の実施形態における溝部の拡大断面図。
【図７】従来の含油軸受を示す断面図。
【符号の説明】
１…ブロワモータ、７，９…含油軸受、８…回転軸、１５…内周面、２１…第１軸受部、２２…第２軸受部、２３…第３軸受部、２４…第４軸受部、２５…第５軸受部、２６，２７…テーパ部、２１ａ，２２ａ，２３ａ，２４ａ，２５ａ，２６ａ，２７ａ…内周面、３１…第１段差部、３２…第２段差部、３４…非多孔質状表面、３５…溝部、４０…空孔、４５…潤滑油、５１ｃ…テーパ面。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a porous oil-impregnated bearing in which a lubricating oil is impregnated.
[0002]
[Prior art]
Conventionally, oil-impregnated bearings are used to support a rotating shaft in an electric motor (specifically, a blower motor) of a vehicle air conditioner. The oil-impregnated bearing is formed of a porous sintered alloy containing lubricating oil, and the inner peripheral surface of the oil-impregnated bearing on which the rotating shaft rotates is cylindrical. When the motor is started, the rotating shaft slides with respect to the inner peripheral surface of the oil-impregnated bearing. A general blower motor has a rotating shaft arranged in a substantially vertical direction and is used as a drive source of an air conditioner. In such a configuration, the lubricating oil impregnated in the oil-impregnated bearing has flowed out through the gap between the inner peripheral surface of the oil-impregnated bearing and the rotating shaft when a long time has passed after the motor is stopped. In addition, a large number of holes are present on the inner peripheral surface of the oil-impregnated bearing, and the lubricating oil is sucked into the holes. For these reasons, there has been a problem that the lubricating oil decreases on the inner peripheral surface of the oil-impregnated bearing to be used for sliding with the rotating shaft. In particular, in a state where the ambient temperature has dropped to around freezing point, the lubricating oil may hardly remain on the inner peripheral surface of the oil-impregnated bearing. In this case, when the motor is started, the frictional resistance between the oil-impregnated bearing and the rotating shaft increases. Further, when the rotating shaft rotates while sliding with the inner peripheral surface of the oil-impregnated bearing, the vibration damping effect by the lubricating oil cannot be obtained. For this reason, unpleasant noise (abnormal noise) may be generated when the motor is started.
[0003]
Accordingly, there is a technique disclosed in Japanese Patent Application Laid-Open No. 2000-346074 as a first solution to the above-described problem. The technique of this publication proposes an impregnated bearing in which a non-porous surface is provided in a cylindrical shape on a part of the inner peripheral surface of the oil-impregnated bearing. Specifically, as shown in FIG. 7, the oil-impregnated bearing 60 includes a central bearing portion 61, an upper end bearing portion 62 provided above the central bearing portion, and a lower end provided below the central bearing portion. It comprises a bearing portion 63. The diameter of the inner peripheral surface of the upper end bearing portion 62 gradually increases toward the upper end. Moreover, the diameter of the inner peripheral surface of the lower end bearing portion 63 gradually increases toward the lower end. In this case, a non-porous surface 64 is formed in the vicinity of the boundary between the central bearing portion 61 and the lower end bearing portion 63. And even if it passes for a long time after a motor stop, lubricating oil is made to remain on the non-porous surface 64. FIG.
[0004]
[Problems to be solved by the invention]
However, the ambient temperature decreases after a long time has elapsed since the motor stopped. Then, the lubricating oil on the porous surface is absorbed into the pores on the porous surface due to heat shrinkage, capillary action, and the like. In this case, since the boundary between the porous surface and the non-porous surface 64 is a smoothly continuous flat surface, the lubricating oil on the porous surface is the lubricating oil on the non-porous surface 64, Often connected to each other. For this reason, the lubricating oil on the non-porous surface 64 was absorbed in the pores together with the lubricating oil on the porous surface absorbed in the pores. As a result, there has been a problem that the lubricating oil on the non-porous surface is depleted and unpleasant noise (abnormal noise) is generated when the motor is started.
[0005]
The present invention has been made to solve the above problems. The purpose is to provide an oil-impregnated bearing capable of preventing abnormal noise at the start-up of the motor by leaving the lubricant on the sliding surface of the rotating shaft and the oil-impregnated bearing even after a long time has elapsed after the motor stops. It is to be.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is applied to an electric motor having a rotating shaft arranged substantially in a vertical direction, and a porous material having a large number of holes is soaked with lubricating oil. An oil-impregnated bearing, the inner peripheral surface of which is provided so as to be parallel to the rotating shaft, the surface of which is porous, and the axial center of the rotating shaft in the bearing, A second bearing portion which is provided below the first bearing portion and has a diameter of an inner peripheral surface substantially equal to a diameter of the inner peripheral surface of the first bearing portion and a non-porous surface; and the first bearing A third bearing portion provided between the first bearing portion and the second bearing portion, wherein a diameter of the inner peripheral surface is larger than a diameter of the inner peripheral surface of the second bearing portion, and the surface thereof is porous. The second bearing portion is provided below the inner peripheral surface, the diameter of the inner peripheral surface gradually increases toward the lower end, and the surface is non-porous. A fourth bearing portion, and a fifth bearing portion provided below the fourth bearing portion, the diameter of the inner peripheral surface being larger than the diameter of the inner peripheral surface of the fourth bearing portion, and the surface thereof being porous. A first step portion is provided at a boundary portion between the second bearing portion and the third bearing portion, and a second step portion is provided at a boundary portion between the fourth bearing portion and the fifth bearing portion. The minimum oil film thickness of the lubricating oil that has oozed out on the surface of the porous inner peripheral surface is x, and the maximum oil film thickness is y, and the inner periphery of the third bearing portion with respect to the inner peripheral surface of the second bearing portion When the step of the surface is a and the step of the inner peripheral surface of the fifth bearing portion with respect to the inner peripheral surface of the fourth bearing portion is b, the first step portion and the second step portion are a <x and formed so as to have a relationship of y <b This is the gist.
[0008]
Claim 2 In the invention described in claim 1 The gist of the invention is that the diameter of the inner peripheral surface on the lower end side of the first bearing portion gradually increases toward the lower side.
[0009]
Claim 3 In the invention described in claim 1, Or 2 The gist of the invention is that the diameter of the inner peripheral surface of the fifth bearing portion gradually increases toward the lower side.
[0010]
Claim 4 In the invention described in claim 1, the claims 1 to 3 In the invention according to any one of the above, the step of the inner peripheral surface of the third bearing portion with respect to the inner peripheral surface of the second bearing portion is a, and the length of the third bearing portion in the substantially vertical direction is z. In this case, the gist is that z / a is 5 to 50.
[0011]
The “action” of the present invention will be described below.
According to the first aspect of the present invention, the first step portion is provided at the boundary portion between the second bearing portion and the third bearing portion, and the second step portion is provided at the boundary portion between the fourth bearing portion and the fifth bearing portion. Each is provided. In this case, during the rotation of the rotating shaft, the lubricating oil that has oozed out from the inner peripheral surface of the first bearing portion moves over the first step portion and moves to the inner peripheral surface of the second bearing portion. However, the lubricating oil once moved to the inner peripheral surface of the second bearing portion gets over the second stepped portion because the diameter of the inner peripheral surface changes suddenly at the boundary between the fourth bearing portion and the fifth bearing portion. Thus, the inner peripheral surface of the fifth bearing portion is not reached. For this reason, lubricating oil can be hold | maintained at the 2nd bearing part and the 4th bearing part whose surface of an internal peripheral surface is non-porous. Therefore, even if a long time elapses after the motor stops, the amount of lubricating oil held on the inner peripheral surfaces of the second bearing portion and the fourth bearing portion does not decrease. In addition, since the diameter of the inner peripheral surface of the first bearing portion is substantially equal to the diameter of the inner peripheral surface of the second bearing portion, the rotary shaft can be in sliding contact with the inner peripheral surface of the oil-impregnated bearing in a larger area. . For this reason, since the rotating shaft is reliably held at the position of the central axis of the oil-impregnated bearing, interference between the rotating shaft and the inner peripheral surface of the impregnated bearing is suppressed. Therefore, it is possible to prevent the generation of abnormal noise when starting up the electric motor.
[0012]
Also The level difference a of the inner peripheral surface of the third bearing portion relative to the inner peripheral surface of the second bearing portion is made smaller than the minimum oil film thickness x of the lubricating oil that has oozed out on the porous surface (a <x). In this case, the lubricating oil that has oozed out on the inner peripheral surface of the first bearing portion moves over the first stepped portion to the inner peripheral surface of the second bearing portion. Further, the step b of the inner peripheral surface of the fifth bearing portion with respect to the inner peripheral surface of the fourth bearing portion is made larger than the maximum oil film thickness y of the lubricating oil (y <b). In this case, the lubricating oil that has moved to the inner peripheral surface of the fourth bearing portion does not get over the second stepped portion and reach the inner peripheral surface of the fifth bearing portion. That is, the lubricating oil can be reliably held in the second bearing portion and the fourth bearing portion whose inner peripheral surface is non-porous. Therefore, even if a long time elapses after the motor is stopped, the amount of lubricating oil held on the inner peripheral surfaces of the second bearing portion and the fourth bearing portion does not decrease. Therefore, it is possible to more reliably prevent the generation of abnormal noise when starting the electric motor.
[0013]
Claim 2 According to the invention described in, the diameter of the inner peripheral surface on the lower end side of the first bearing portion gradually increases as it goes downward. In this case, the clearance between the inner peripheral surface and the rotary shaft is increased on the lower end side of the inner peripheral surface of the first bearing portion. For this reason, the lubricating oil that oozes out from the inner peripheral surface of the first bearing portion moves to the inner peripheral surface of the second bearing portion along the inner peripheral surface of the third bearing portion without being transmitted to the rotating shaft. For this reason, the lubricating oil gets over the first step portion and is efficiently replenished to the inner peripheral surface of the second bearing portion. Therefore, it is possible to prevent the lubricating oil from being depleted in the second bearing portion and the fourth bearing portion whose inner peripheral surface is non-porous. Therefore, it is possible to more reliably prevent the generation of abnormal noise when starting the electric motor.
[0014]
Claim 3 According to the invention described in, the diameter of the inner peripheral surface of the fifth bearing portion gradually increases as it goes downward. In this case, the corner formed at the lower end portion of the inner peripheral surface of the fifth bearing portion is reduced. Therefore, interference between the rotating shaft and the inner peripheral surface of the impregnated bearing is reliably suppressed. Therefore, it is possible to further prevent the generation of abnormal noise when starting up the electric motor.
[0015]
Claim 4 According to the invention described in the above, z / a when the step of the inner peripheral surface of the third bearing portion with respect to the inner peripheral surface of the second bearing portion is a and the length of the third bearing portion in the substantially vertical direction is z. The value of is 5-50. If it does in this way, the area which a rotating shaft and the internal peripheral surface of a 1st bearing part slidably contact can be ensured enough. For this reason, a rotating shaft is reliably hold | maintained by the position of the center axis | shaft of an oil-impregnated bearing. Therefore, interference between the rotating shaft and the inner peripheral surface of the impregnated bearing is more reliably suppressed. Therefore, it is possible to further prevent the generation of abnormal noise when starting up the electric motor.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment in which the present invention is embodied in an oil-impregnated bearing 9 used in a blower motor 1 will be described below with reference to FIGS.
[0017]
FIG. 1 is a cross-sectional view of a blower motor 1 in this embodiment. The blower motor 1 includes a substantially cylindrical yoke housing 2 having openings at both ends, and housing cases 3 and 4 fixed so as to close both ends of the yoke housing 2.
[0018]
A magnet 6 is disposed on the inner peripheral side of the yoke housing 2 so as to surround the armature 5. An oil-impregnated bearing 7 is fixed to the housing case 3, and a base end portion of the rotating shaft 8 extending from the armature 5 is rotatably supported by the oil-impregnated bearing 7. On the other hand, an oil-impregnated bearing 9 is fixed to the housing case 4, and a rotating shaft 8 extending from the armature 5 is rotatably supported by the oil-impregnated bearing 9. The tip of the rotating shaft 8 protrudes outside from the housing case 4, and a blower fan (not shown) is fixed to the tip of the rotating shaft 8. A commutator 10 is disposed at a position between the armature 5 and the oil-impregnated bearing 9 on the rotary shaft 8. The commutator 10 is fixed so as to rotate integrally with the rotary shaft 8. Further, a brush 11 is disposed so as to be in sliding contact with the outer peripheral surface of the commutator 10.
[0019]
The blower motor 1 is fixed to a vehicle (not shown) so that the rotary shaft 8 is along the vertical direction. When the motor 1 is started, DC power from an external power source (not shown) is supplied to the armature 5 through the brush 11, the commutator 10, and the like, so that the armature 5 rotates with the rotating shaft 8. Thereby, the air blowing operation by the air blowing fan fixed to the tip of the rotating shaft 8 is performed.
[0020]
Next, the structure of the oil-impregnated bearings 7 and 9 in this embodiment is demonstrated. The oil-impregnated bearings 7 and 9 are made of a porous sintered metal having a large number of pores. The oil-impregnated bearings 7 and 9 are formed in a substantially cylindrical shape by compression molding powder powder, sintering and finishing. Numerous continuous pores exist on the surface and inside of the oil-impregnated bearings 7 and 9. The air holes 40 shown in FIGS. 3A and 3B are part of continuous pores in the vicinity of the surfaces of the oil-impregnated bearings 7 and 9, and the inside thereof is impregnated with the lubricating oil 45. The lubricating oil 45 can freely move on the surfaces and inside of the oil-impregnated bearings 7 and 9 through the continuous pores and the holes 40.
[0021]
An enlarged cross-sectional view of the oil-impregnated bearing 9 in FIG. 1 is shown in FIGS. The substantially cylindrical oil-impregnated bearing 9 is provided with through holes that open at the upper end surface and the lower end surface. The oil-impregnated bearing 9 includes an inner peripheral surface 15 as an inner surface of the through hole. The rotary shaft 8 is inserted into the through hole of the oil-impregnated bearing 9 and is supported at both the upper end portion and the lower end portion of the motor 1. When the motor 1 is started, the rotary shaft 8 slides with the inner peripheral surface 15 of the oil-impregnated bearing 9.
[0022]
The oil-impregnated bearing 9 is divided into a plurality of bearing portions by a plane perpendicular to the axial direction of the rotary shaft 8. As shown in FIG. 2A, the second bearing portion 22 is disposed in the center of the oil-impregnated bearing 9. A first bearing portion 21 and a third bearing portion 23 are disposed above the second bearing portion 22. Further, a fourth bearing portion 24 and a fifth bearing portion 25 are disposed below the second bearing portion 22. Furthermore, taper portions 26 and 27 are disposed at both ends of the oil-impregnated bearing 9, respectively.
[0023]
As shown in FIG. 2, the third bearing portion 23 is disposed between the first bearing portion 21 and the second bearing portion 22. In this case, the diameter d of the inner peripheral surface 21a of the first bearing portion 21. ₀ Is equal to the diameter of the inner peripheral surface 22a of the second bearing portion 22, and the diameter d of the inner peripheral surface 23a of the third bearing portion 23. ₁ Is the diameter d of the inner peripheral surface 22a of the second bearing portion 22. ₀ Is bigger than. For this reason, the groove part 35 which makes the inner peripheral surface 23a of the 3rd bearing part 23 a bottom is formed in the inner peripheral surface 15 of the oil-impregnated bearing 9 cyclically | annularly along the circumferential direction. The groove portion 35 includes an inner peripheral surface 23 a of the third bearing portion 23, an inner side surface 22 b of the second bearing portion 22, and an inner side surface 21 b of the first bearing portion 21. At the boundary between the second bearing portion 22 and the third bearing portion 23, a first step portion 31 comprising an inner peripheral surface 22a of the second bearing portion 22 and an inner side surface 22b of the second bearing portion 22 is circumferential. It is formed in an annular shape along the direction. The diameter of the inner peripheral surface 15 of the oil-impregnated bearing 9 changes suddenly at the first step portion 31.
[0024]
A fourth bearing portion 24 is disposed below the second bearing portion 22. The diameter of the inner peripheral surface 24a of the fourth bearing portion 24 is d at the upper end portion. ₀ D at the lower end ₂ It is. As shown in FIG. 2, the diameter of the inner peripheral surface 24 a of the fourth bearing portion 24 gradually increases from the upper end portion to the lower end portion. Further, a fifth bearing portion 25 is disposed below the fourth bearing portion 24. Diameter d of inner peripheral surface 25a of fifth bearing portion 25 _Three Is the diameter d of the inner peripheral surface 24a of the fourth bearing portion 24. ₂ Is bigger than. For this reason, the second step portion 32 composed of the inner peripheral surface 24a and the inner side surface 24b of the fourth bearing portion 24 is provided along the circumferential direction at the boundary portion between the fourth bearing portion 24 and the fifth bearing portion 25. It is formed in a ring shape.
[0025]
Tapered portions 26 and 27 are provided above the first bearing portion 21 and below the fifth bearing portion 25. The diameters of the inner peripheral surfaces 26 a and 27 a of the taper portions 26 and 27 are gradually increased toward the both end portions of the oil-impregnated bearing 9. In this way, the rotating shaft 8 is prevented from interfering with both ends of the inner peripheral surface 15 of the oil-impregnated bearing 9.
[0026]
As shown in FIG. 2, the taper portions 26, 27, the first bearing portion 21, the third bearing portion 23, and the fifth bearing portion 25 have inner surfaces 26a, 27a, 21a, 23a, 25a having a porous surface. It has become. The inner peripheral surfaces 22 a and 24 a of the second bearing portion 22 and the fourth bearing portion 24 are non-porous surfaces 34.
[0027]
Next, enlarged views of the vicinity of the first step portion 31 and the second step portion 32 are shown in FIGS. 3 (a) and 3 (b). As shown in FIG. 3A and FIG. 3B, one end side of the pore 40 is an opening on the porous surface. For this reason, when the ambient temperature decreases after the motor 1 is stopped, the lubricating oil 45 is absorbed into the holes 40 from the opening due to thermal contraction, capillary action, or the like. On the other hand, in the non-porous surface 34, the opening of the void 40 is crushed. For this reason, the lubricating oil 45 is not absorbed into the pores 40 from the non-porous surface 34.
[0028]
In the present embodiment, the step a in the first step portion 31 and the step b in the second step portion 32 are determined based on the oil film thickness of the lubricating oil 45 on the porous surface. Specifically, the oil film thickness of the lubricating oil 45 is set to 16 μm to 20 μm when the motor 1 is started. In this case, the level difference a is set to be smaller than the minimum oil film thickness x of the lubricating oil 45. This is because the lubricating oil 45 that has exuded to the inner peripheral surface 21 a of the first bearing portion 21 gets over the first step portion 31 and reaches the inner peripheral surface 22 a of the second bearing portion 22. Accordingly, the step a in the first step portion 31 is set to 5 μm to 15 μm.
[0029]
Further, the step b in the second step portion 32 is set to be larger than the maximum oil film thickness y of the lubricating oil 45. This is to prevent the lubricating oil 45 on the inner peripheral surface 24 a of the fourth bearing portion 24 from getting over the second stepped portion 32 and reaching the inner peripheral surface 25 a of the fifth bearing portion 25. Accordingly, the step b in the second step portion 32 is set to 30 μm or more.
[0030]
Here, the reason why the step b is set larger than the maximum oil film thickness y of the non-porous surface will be specifically described. When the step b is smaller than the maximum oil film thickness y of the non-porous surface, the lubricating oil 45 on the inner peripheral surface 24a of the fourth bearing portion 24 gets over the second step portion 32 and the inner periphery of the fifth bearing portion 25. The surface 25a may be connected to the lubricating oil 45 on the surface 25a. When the ambient temperature decreases after the motor 1 is stopped, the lubricating oil 45 on the inner peripheral surface 25a of the fifth bearing portion 25 is absorbed into the pores 40 on the porous surface due to thermal contraction, capillary action, or the like. Then, the lubricating oil 45 on the non-porous surface 34 is absorbed into the pores 40 on the porous surface together with the lubricating oil 45 on the porous surface. As a result, the lubricating oil 45 on the non-porous surface 34 is depleted. For this reason, it is more desirable that the step b in the second step portion 32 is set larger than the maximum oil film thickness y of the porous surface.
[0031]
The size of the groove portion 35 is determined by the step a in the first step portion 31 and the length z of the third bearing portion 23 in the substantially vertical direction. In this case, the groove part 35 is formed so that z / a has a relationship of 5-50. In the present embodiment, the step a is set to 5 μm to 15 μm based on the oil film thickness of the lubricating oil 45 on the porous surface. For this reason, it is most desirable that the length z is set to 100 μm to 200 μm.
[0032]
Next, an example of a method for manufacturing the oil-impregnated bearing 9 will be described. First, a predetermined mold is filled with powder metal as a raw material. The powder metal is compression-molded by a press or the like together with a core material for forming a through hole. After the compression molding, when the core is extracted from the molded body, a substantially cylindrical molded body having a through hole at the center is formed. Thereafter, the compression-molded body becomes a porous sintered body through a firing step. As a result, a large number of holes are formed on the outer surface of the main body of the oil-impregnated bearing 9 and the inner surface of the through hole. Here, in order to make a part of the inner surface of the through-hole into the non-porous surface 34, the opening of the pore 40 on the porous surface slides the core material or the like having irregularities on the surface. It is partially crushed by removing it. In this way, the non-porous surface 34 is formed on a part of the inner surface of the through hole. Next, processing for finishing the inner peripheral surface 15 and the outer peripheral surface of the main body of the oil-impregnated bearing 9 is performed. At this time, tapered surfaces 26a and 27a, a groove portion 35, a second step portion 32, and the like are formed on the inner peripheral surface 15. And the oil-impregnated bearing 9 is made by impregnating the main body of the oil-impregnated bearing 9 with the lubricating oil 45.
[0033]
Next, the movement of the lubricating oil 45 during rotation of the rotating shaft 8 will be described with reference to FIGS. 3 (a) and 3 (b). When the rotating shaft 8 rotates with the start of the blower motor 1, the rotating shaft 8 comes into sliding contact with the inner peripheral surface 15 of the oil-impregnated bearing 9. Then, the inner peripheral surface 15 of the oil-impregnated bearing 9 generates heat due to contact friction. For this reason, in the vicinity of the surface of the inner peripheral surface 15, the volume of the lubricating oil 45 absorbed in the air holes 40 expands. The lubricating oil 45 filled in the pores 40 on the porous surface oozes out from the openings of the pores 40. On the other hand, on the non-porous surface 34, the opening of the void 40 is clogged, so that the lubricating oil 45 does not ooze out.
[0034]
The lubricating oil 45 oozing out from the inner peripheral surface 21 a of the first bearing portion 21 reaches the inner peripheral surface 23 a of the third bearing portion 23 along the inner peripheral surface 21 a and the surface of the rotary shaft 8. The lubricating oil 45 gets over the first step portion 31 and reaches the inner peripheral surface 22 a of the second bearing portion 22.
[0035]
When the rotating shaft 8 is stationary as the blower motor 1 is stopped, the ambient temperature of the oil-impregnated bearing 9 is lowered. Then, the lubricating oil 45 that has oozed out into the inner peripheral surface 15 is again absorbed into the pores 40 of the porous surface due to thermal contraction due to temperature change, capillary action, and the like. However, on the non-porous surface 34, the openings of the pores 40 are clogged, so that the lubricating oil 45 is not absorbed into the pores 40 from the non-porous surface 34. Therefore, the lubricating oil 45 remains on the inner peripheral surfaces 22 a and 24 a of the second bearing portion 22 and the fourth bearing portion 24 without being absorbed into the air holes 40. That is, the lubricating oil 45 is supplied from the pores 40 on the porous surface at a high temperature, and is recovered in the pores 40 on the porous surface at a low temperature.
[0036]
Therefore, according to the first embodiment, the following features can be obtained.
(1) A first step portion 31 is provided at the boundary between the second bearing portion 22 and the third bearing portion 23, and a second step portion 32 is provided at the boundary portion between the fourth bearing portion 24 and the fifth bearing portion 25. Is provided. In this case, the diameter of the inner peripheral surface 15 changes suddenly at the second step portion 32. For this reason, even if it passes for a long time after the motor 1 stops, the lubricating oil 45 can be hold | maintained to the internal peripheral surfaces 22a and 24a of the 2nd bearing part 22 and the 4th bearing part 24. FIG. In addition, the diameter of the inner peripheral surface 21 a of the first bearing portion 21 is substantially equal to the diameter of the inner peripheral surface 22 a of the second bearing portion 22. For this reason, the rotating shaft 8 can be in sliding contact with the inner peripheral surface 15 of the oil-impregnated bearing 9 in a larger area. Therefore, the rotating shaft 8 is reliably held at the position of the central axis of the oil-impregnated bearing 9. Therefore, interference between the rotating shaft 8 and the inner peripheral surface 15 of the oil-impregnated bearing 9 is suppressed, and the generation of abnormal noise when the motor 1 is started can be prevented.
[0037]
(2) The step a of the inner peripheral surface 23a of the third bearing portion 23 relative to the inner peripheral surface 22a of the second bearing portion 22 is made smaller than the minimum oil film thickness x of the lubricating oil 45 that has oozed out on the porous surface. (A <x). In this case, the lubricating oil 45 that has oozed out on the inner peripheral surface 21 a of the first bearing portion 21 moves over the first step portion 31 and moves to the inner peripheral surface 22 a of the second bearing portion 22. Further, the step b of the inner peripheral surface 25a of the fifth bearing portion 25 with respect to the inner peripheral surface 24a of the fourth bearing portion 24 is made larger than the maximum oil film thickness y of the lubricating oil 45 (y <b). In this case, the lubricating oil 45 that has moved to the inner peripheral surface 24 a of the fourth bearing portion 24 does not get over the second step portion 32 and reach the inner peripheral surface 25 a of the fifth bearing portion 25. That is, the lubricating oil 45 can be reliably held on the porous surfaces of the inner peripheral surfaces 22a and 24a of the second bearing portion 22 and the fourth bearing portion 24. Therefore, even if a long time elapses after the motor 1 is stopped, the amount of the lubricating oil 45 held on the inner peripheral surfaces 22a and 24a of the second bearing portion 22 and the fourth bearing portion 24 does not decrease. Accordingly, it is possible to more reliably prevent the generation of abnormal noise when the motor 1 is started.
[0038]
(3) z / when the step of the inner peripheral surface 23a of the third bearing portion 23 with respect to the inner peripheral surface 22a of the second bearing portion 22 is a and the length of the third bearing portion 23 in the substantially vertical direction is z. The value of a is 5-50. In this way, it is possible to ensure a sufficient area where the rotary shaft 8 and the inner peripheral surface 21a of the first bearing portion 21 are in sliding contact. For this reason, the rotating shaft 8 is reliably held by the position of the central axis of the oil-impregnated bearing 9. Therefore, interference between the rotating shaft 8 and the inner peripheral surface 15 of the oil-impregnated bearing 9 is more reliably suppressed. Accordingly, it is possible to further prevent the generation of abnormal noise when the motor 1 is started.
(Second Embodiment)
Next, a second embodiment of the oil-impregnated bearing 9 that embodies the present invention and is used in the blower motor 1 will be described with reference to FIGS. 4 (a), 4 (b), and 4 (c). In the second embodiment, detailed description of the same parts as those in the first embodiment is omitted.
[0039]
In the present embodiment, as shown in FIGS. 4A and 4C, the diameter of the inner peripheral surface 51a gradually increases at the lower end portion of the first bearing portion 51 as it goes downward. For this reason, the taper surface 51c is formed in the annular | circular shape along the circumferential direction in the lower end part side of the internal peripheral surface 51a of the 1st bearing part 51. As shown in FIG. In this case, the clearance between the inner peripheral surface 51a and the rotary shaft 8 becomes larger than when the tapered surface 51c is not formed at the lower end portion of the inner peripheral surface 51a. In addition, since there is no corner formed by the inner peripheral surface 51 a and the inner side surface 51 b of the first bearing portion 51, the lubricating oil 45 that has oozed out on the inner peripheral surface 51 a of the first bearing portion 51 is less likely to be transmitted to the rotary shaft 8. . For this reason, the lubricating oil 45 moves along the inner peripheral surface 53 a of the third bearing portion 53 and reaches the inner peripheral surface 52 a of the second bearing portion 52 after getting over the first stepped portion 31. In this case, it is desirable that the position 66 where the diameter of the inner peripheral surface 51 a of the first bearing portion 51 changes is provided below the intermediate position between the upper end portion and the lower end portion of the first bearing portion 51. This is because the sliding contact area between the rotary shaft 8 and the inner peripheral surface 15 of the oil-impregnated bearing 9 is not reduced.
[0040]
As shown in FIGS. 4A and 4B, the diameter of the inner peripheral surface 55a of the fifth bearing portion 55 is d at the upper end portion. _Three D at the lower end _Four It is. The inner peripheral surface 55a of the fifth bearing portion 55 gradually increases as it goes downward from the upper end portion to the lower end portion. By doing in this way, it can prevent more reliably that the rotating shaft 8 interferes with the both ends of the internal peripheral surface 15 of the oil-impregnated bearing 9 at the time of starting of the motor 1.
[0041]
Therefore, according to the second embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.
(1) The diameter of the inner peripheral surface 51a on the lower end side of the first bearing portion 51 gradually increases as it goes downward. For this reason, the lubricating oil 45 that has oozed out of the inner peripheral surface 51 a of the first bearing portion 51 gets over the first step portion 31 and is efficiently replenished to the inner peripheral surface 52 a of the second bearing portion 52. Therefore, it is possible to prevent the lubricating oil 45 from being depleted in the second bearing portion 52 and the fourth bearing portion 54 in which the inner peripheral surface 52a has a non-porous surface. Therefore, it is possible to more reliably prevent the generation of abnormal noise when the motor 1 is started.
[0042]
(2) The diameter of the inner peripheral surface 55a of the fifth bearing portion 55 gradually increases as it goes downward. In this case, the corner portion formed by the inner peripheral surface 55a of the fifth bearing portion 55 and the inner peripheral surface 57a of the tapered portion 57 is reduced. Therefore, interference between the rotating shaft 8 and the inner peripheral surface 15 of the oil-impregnated bearing 9 is reliably suppressed. Accordingly, it is possible to further prevent the generation of abnormal noise when the motor 1 is started.
[0043]
In addition, you may change the said embodiment as follows.
-In the said embodiment, the main body of the oil-impregnated bearing 9 was formed with the porous sintered alloy. Specifically, it was formed by compression-molding, firing and finishing a powder of carbon steel, nickel alloy, copper alloy, aluminum alloy or the like. However, the main body of the oil-impregnated bearing 9 may be formed using a pure metal powder such as iron, nickel, copper, or aluminum.
[0044]
In the embodiment, the main body of the oil-impregnated bearing 9 is formed of a porous sintered alloy. However, the oil-impregnated bearing 9 may be formed of a porous inorganic sintered body. Specific examples include silicon carbide, aluminum nitride, silicon nitride, alumina, mullite, zirconia, and graphite.
[0045]
-In the said embodiment, the oil-impregnated bearing 9 was used for support of the rotating shaft 8 of the electric motor of a vehicle air conditioner. However, the oil-impregnated bearing 9 may be used to support a shaft other than the rotating shaft 8 of the electric motor.
[0046]
In the above embodiment, the figure 6 As shown to (a), the groove part 35 formed in the position of the 3rd bearing part 23 of the internal peripheral surface 15 of the oil-impregnated bearing 9 was a recessed part with a substantially square cross section. However, the shape of the groove 35 is 6 (B), figure 6 As shown in (c), a recess having a substantially triangular cross section or a recess having a substantially arc cross section may be used.
[0047]
In the embodiment, the angle θ at the first step portion 31 and the second step portion 32 ₁ , Angle θ ₂ The shape was a right angle or an obtuse angle. However, the angle θ between the first step portion 31 and the second step portion 32. ₁ , Angle θ ₂ The shape is not limited to this, and may be a shape with chamfered corners (c surface) or a curved shape (R surface).
[0048]
In the above-described embodiment, one groove portion 35 is formed on the inner peripheral surface 15 at the position of the inner peripheral surface 23 a of the third bearing portion 23. But figure 5 (A), figure 5 As shown in (b), other groove portions 36 may be formed on the inner peripheral surface 15 in addition to the groove portions 35. In this case, the sixth bearing portion 28 is disposed between the fourth bearing portion 24 and the fifth bearing portion 25. The diameter of the inner peripheral surface 26 a is larger than the diameter of the fourth bearing portion 24. For this reason, on the inner peripheral surface 15 of the oil-impregnated bearing 9, there is a groove portion 36 composed of the inner peripheral surface 26a of the sixth bearing portion 28, the inner side surface 24b of the fourth bearing portion 24, and the inner side surface 25b of the fifth bearing portion 25. It is formed. A second step portion 32 is formed at the boundary between the fourth bearing portion 24 and the sixth bearing portion 28. The step b in the second step portion 32 is formed so as to have a relationship of y <b, where y is the maximum oil film thickness of the lubricating oil 45 that has oozed into the porous surface.
[0049]
In the embodiment, the step a of the inner peripheral surface 23a of the third bearing portion 23 with respect to the inner peripheral surface 22a of the second bearing portion 22 is set to 5 μm to 15 μm, and the fifth bearing with respect to the inner peripheral surface 24a of the fourth bearing portion 24 is set. Although the step b of the inner peripheral surface 25a of the portion 25 is set to 30 μm or more, it is not limited to this. In other words, any step having a relationship of step a <minimum oil film thickness x, step b> maximum oil film thickness y may be used, and these steps a and b can be appropriately changed according to the type of the lubricating oil 45 and the like. However, the step a is preferably set within a clearance range between the inner peripheral surfaces 21 a and 22 a of the first bearing portion 21 and the second bearing portion 22 and the rotary shaft 8.
[0050]
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) Said A motor comprising an oil-impregnated bearing. In this way, a motor capable of suppressing abnormal noise at the start-up of the motor without reducing the lubricating oil on the inner peripheral surface of the oil-impregnated bearing even after a long time has passed after the motor has stopped is provided. be able to.
[0051]
【The invention's effect】
As detailed above, each Claim In terms According to the described invention, even when the ambient temperature drops after the motor is stopped, the lubricating oil remains on the sliding surface between the rotating shaft and the oil-impregnated bearing, thereby preventing the motor from generating abnormal noise at the time of starting. An oil-impregnated bearing that can be provided can be provided.
[0052]
Claim 2 According to the invention described in the above, since the lubricating oil exuding from the porous surface is efficiently replenished to the non-porous surface, it is possible to prevent the generation of abnormal noise during startup of the electric motor. .
[0053]
Claim 3 Or 4 Since the interference between the rotating shaft and the inner peripheral surface of the impregnated bearing is suppressed, it is possible to further prevent the generation of abnormal noise when the motor is started.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a blower motor according to an embodiment.
2A is a cross-sectional view showing an oil-impregnated bearing according to the present embodiment, and FIG. 2B is an enlarged cross-sectional view in the vicinity of a first step portion and a second step portion.
FIGS. 3A and 3B are explanatory views showing the movement of the lubricating oil when the motor is rotating, and FIG. 3B is an explanatory view showing the movement of the lubricating oil when the motor is stopped.
4A is a sectional view showing an oil-impregnated bearing in a second embodiment, FIG. 4B is an enlarged sectional view in the vicinity of a fifth bearing portion, and FIG. 4C is an enlarged sectional view in the vicinity of a first step portion;
5A is a cross-sectional view showing an oil-impregnated bearing in another embodiment, and FIG. 5B is an enlarged cross-sectional view in the vicinity of a first step portion and a second step portion.
6A is an enlarged cross-sectional view of a groove portion in the present embodiment, FIG. 6B is an enlarged cross-sectional view of the groove portion in another embodiment, and FIG. 6C is an enlarged cross-sectional view of the groove portion in another embodiment.
FIG. 7 is a cross-sectional view showing a conventional oil-impregnated bearing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Blower motor, 7, 9 ... Oil-impregnated bearing, 8 ... Rotary shaft, 15 ... Inner peripheral surface, 21 ... 1st bearing part, 22 ... 2nd bearing part, 23 ... 3rd bearing part, 24 ... 4th bearing part, 25 ... fifth bearing portion, 26, 27 ... tapered portion, 21a, 22a, 23a, 24a, 25a, 26a, 27a ... inner peripheral surface, 31 ... first step portion, 32 ... second step portion, 34 ... non-porous Material surface, 35 ... groove, 40 ... hole, 45 ... lubricating oil, 51c ... tapered surface.

Claims

An oil-impregnated bearing that is applied to an electric motor whose rotating shaft is arranged along a substantially vertical direction, in which lubricating oil is impregnated into a porous material having a large number of holes,
A first bearing portion provided with an inner peripheral surface parallel to the rotation axis, the surface of which is porous;
The bearing is provided at the center in the axial direction of the rotating shaft and below the first bearing portion. The inner peripheral surface has a diameter substantially equal to the inner peripheral surface diameter of the first bearing portion, and the surface thereof is non-porous. A second bearing portion that is of a quality;
A third bearing that is provided between the first bearing portion and the second bearing portion, has a diameter of an inner peripheral surface larger than a diameter of the inner peripheral surface of the second bearing portion, and has a porous surface. And
A fourth bearing portion provided below the second bearing portion, the diameter of the inner peripheral surface gradually increases toward the lower end, and the surface thereof is non-porous;
A fifth bearing portion provided below the fourth bearing portion, having a diameter of an inner peripheral surface larger than a diameter of the inner peripheral surface of the fourth bearing portion, and a porous surface thereof;
A first step portion is provided at a boundary portion between the second bearing portion and the third bearing portion, and a second step portion is provided at a boundary portion between the fourth bearing portion and the fifth bearing portion, respectively .
An inner peripheral surface of the third bearing portion with respect to an inner peripheral surface of the second bearing portion, where x is the minimum oil film thickness of the lubricating oil that has oozed out on the surface of the porous inner peripheral surface, and y is the maximum oil film thickness. Where the step of the inner peripheral surface of the fifth bearing portion with respect to the inner peripheral surface of the fourth bearing portion is b, the first step portion and the second step portion are a <x and y An oil-impregnated bearing formed so as to have a relationship of <b .

2. The oil-impregnated bearing according to claim 1, wherein the diameter of the inner peripheral surface on the lower end side of the first bearing portion gradually increases toward the lower side .

3. The oil-impregnated bearing according to claim 1, wherein the diameter of the inner peripheral surface of the fifth bearing portion gradually increases toward the lower side . 4.

When the step of the inner peripheral surface of the third bearing portion with respect to the inner peripheral surface of the second bearing portion is a and the length of the third bearing portion in the substantially vertical direction is z, z / a is 5 to 50. The oil-impregnated bearing according to any one of claims 1 to 3, wherein the oil-impregnated bearing is provided.