WO2019159787A1

WO2019159787A1 - Fluid dynamic pressure bearing device and motor provided with same

Info

Publication number: WO2019159787A1
Application number: PCT/JP2019/004234
Authority: WO
Inventors: 直士大島
Original assignee: Ntn株式会社
Priority date: 2018-02-19
Filing date: 2019-02-06
Publication date: 2019-08-22
Also published as: JP2019143688A

Abstract

This fluid dynamic pressure bearing device 1 is provided with: a bottomed cylindrical housing 7; a bearing sleeve 8; a shaft member 2 having a shaft part 2a that is inserted into the inner circumference of the bearing sleeve 8 in a removable manner; an annular part 9 which forms a radial gap Ga between itself and the outer circumferential surface of the shaft member 2; radial bearing parts R1, R2; a thrust bearing part T; and a bottom gap Gb which houses the thrust bearing part T. A part of the internal space of the housing 7 is filled with a lubricant oil 11; and the remaining region of the internal space including the radial gap Ga forms a void part that is not filled with the lubricant oil 11. The outside diameter d4 of a second portion 2b1 of the outer circumference of the shaft member 2, said second portion 2b1 facing the inner circumferential surface 9a of the annular part 9, is larger than the outside diameter d3 of a first portion 2a1 of the outer circumference of the shaft member 2, said first portion 2a1 facing the inner circumferential surface 8a1 of the bearing sleeve 8.

Description

流体動圧軸受装置及びこれを備えたモータFluid dynamic bearing device and motor equipped with the same

　本発明は、流体動圧軸受装置及びこれを備えたモータに関する。 The present invention relates to a fluid dynamic pressure bearing device and a motor including the same.

　周知のように、流体動圧軸受装置は、高速回転、高回転精度および低騒音等の特長を有する。このため、流体動圧軸受装置は、情報機器をはじめとする種々の電気機器に搭載されるモータ用の軸受装置として、具体的には、ＨＤＤ等のディスク駆動装置に組み込まれるスピンドルモータ用、これらディスク駆動装置やＰＣ等に組み込まれるファンモータ用、あるいはレーザビームプリンタ（ＬＢＰ）に組み込まれるポリゴンスキャナモータ用の軸受装置などとして好適に使用されている。 As is well known, the fluid dynamic bearing device has features such as high speed rotation, high rotation accuracy, and low noise. For this reason, the fluid dynamic bearing device is used as a bearing device for a motor mounted on various electric devices such as information devices, specifically for a spindle motor incorporated in a disk drive device such as an HDD. It is suitably used as a bearing device for a fan motor incorporated in a disk drive device or a PC, or a polygon scanner motor incorporated in a laser beam printer (LBP).

　流体動圧軸受装置の一例が下記の特許文献１に記載されている。この流体動圧軸受装置は、有底筒状（筒状部とその軸方向一端を閉塞する底部とを一体に有する形状）のハウジングと、ハウジングの内周に配設された軸受スリーブと、挿脱自在に軸受スリーブの内周に挿入された軸部材と、ラジアル軸受隙間に形成される潤滑油の油膜で軸部材をラジアル方向に支持するラジアル軸受部と、軸部材の一端を支持するスラスト軸受部と、スラスト軸受部を収容した底隙間と、ハウジングの開口部内周に固定された環状部材（シール部材）とを備える。 An example of a fluid dynamic bearing device is described in Patent Document 1 below. This fluid dynamic pressure bearing device includes a bottomed cylindrical housing (a shape that integrally includes a cylindrical portion and a bottom portion that closes one end in the axial direction thereof), a bearing sleeve disposed on the inner periphery of the housing, A shaft member that is removably inserted into the inner periphery of the bearing sleeve, a radial bearing portion that supports the shaft member in the radial direction with a lubricating oil film formed in a radial bearing gap, and a thrust bearing that supports one end of the shaft member And a bottom gap accommodating the thrust bearing portion, and an annular member (seal member) fixed to the inner periphery of the opening of the housing.

　この流体動圧軸受装置において、環状部材は、その一端面（相対的に軸受内部側に位置する端面）を軸受スリーブの対向端面に当接させた状態でハウジングの内周に固定されている。そのため、ハウジングに対する軸受スリーブの固定力（軸受スリーブの抜去力）が高まり、軸方向におけるハウジングと軸受スリーブの相対位置、ひいては所望の軸受性能が安定的に維持される。また、この流体動圧軸受装置は、ハウジングの内部空間全域を潤滑油で満たした、いわゆるフルフィル状態で使用されるものであり、環状部材の内周面と軸部材の外周面との間にシール空間（ラジアル軸受隙間よりも隙間幅の大きい径方向隙間）が設けられる。シール空間は、潤滑油の温度変化に伴う容積変化量を吸収するバッファ機能を有し、想定される温度変化の範囲内において潤滑油の油面を常にシール空間の範囲内に保持し得るように設計されている。従って、潤滑油の外部漏洩に起因した軸受性能の低下や周辺環境の汚染が可及的に防止される。 In this fluid dynamic pressure bearing device, the annular member is fixed to the inner periphery of the housing with its one end surface (an end surface relatively located on the bearing inner side) in contact with the opposite end surface of the bearing sleeve. Therefore, the fixing force of the bearing sleeve with respect to the housing (the pulling force of the bearing sleeve) is increased, and the relative position between the housing and the bearing sleeve in the axial direction, and thus the desired bearing performance is stably maintained. The fluid dynamic bearing device is used in a so-called full-fill state in which the entire inner space of the housing is filled with lubricating oil, and a seal is provided between the inner peripheral surface of the annular member and the outer peripheral surface of the shaft member. A space (a radial gap having a gap width larger than the radial bearing gap) is provided. The seal space has a buffer function that absorbs the volume change accompanying the temperature change of the lubricating oil, so that the oil level of the lubricating oil can always be kept within the range of the seal space within the assumed temperature change range. Designed. Therefore, deterioration of bearing performance and contamination of the surrounding environment due to external leakage of lubricating oil are prevented as much as possible.

　しかしながら、ハウジングの内部空間全域を潤滑油で満たした、いわゆるフルフィル状態の潤滑油含浸構造を採用すると、流体動圧軸受装置の組立て後に、真空含浸等の煩雑な手法を用いてハウジングの内部空間全域を潤滑油で満たし、かつ潤滑油のシール空間における油面位置を精度良く管理する（潤滑油の充填量を微調整する）必要がある。そのため、従来の含油構造では流体動圧軸受装置に対する更なる低コスト化の要請に対応することが難しい、という問題が指摘されていた。 However, if a so-called full-filled lubricating oil impregnation structure in which the entire internal space of the housing is filled with lubricating oil is adopted, the entire internal space of the housing is used by using a complicated method such as vacuum impregnation after assembly of the fluid dynamic bearing device. And the position of the oil surface in the sealing space of the lubricating oil must be accurately controlled (fine adjustment of the filling amount of the lubricating oil). Therefore, it has been pointed out that the conventional oil-impregnated structure is difficult to meet the demand for further cost reduction of the fluid dynamic bearing device.

　そこで、本出願人は、上記課題を解決すべく特許文献２に記載の如き流体動圧軸受装置を提案している。すなわち、この流体動圧軸受装置は、軸方向一端が閉塞されると共に軸方向他端が開口している有底筒状のハウジングと、ハウジングの内周に配設された軸受スリーブと、挿脱可能に軸受スリーブの内周に挿入された軸部材と、一端面を軸受スリーブの一端面に当接させた状態でハウジングの一端内周に固定され、軸部材の外周面との間に径方向隙間を形成する環状部材と、軸受スリーブの内周面と軸部材の外周面との間のラジアル軸受隙間に形成される潤滑油の油膜で軸部材をラジアル方向に支持するラジアル軸受部と、軸部材の一端をスラスト方向に支持するスラスト軸受部と、スラスト軸受部を収容し、潤滑油で満たされた底隙間とを備えたもので、ハウジングの内部空間に空隙部が設けられ、ラジアル軸受隙間の隙間幅をＷ１、径方向隙間の隙間幅をＷ２としたとき、３０×Ｗ１≦Ｗ２≦２５０×Ｗ１の関係式を満たすことを特徴とする。 Therefore, the present applicant has proposed a fluid dynamic bearing device as described in Patent Document 2 in order to solve the above problems. That is, this fluid dynamic pressure bearing device includes a bottomed cylindrical housing that is closed at one end in the axial direction and opened at the other end in the axial direction, a bearing sleeve disposed on the inner periphery of the housing, A shaft member that is inserted into the inner periphery of the bearing sleeve, and is fixed to the inner periphery of one end of the housing with one end surface in contact with the one end surface of the bearing sleeve. An annular member that forms a gap, a radial bearing portion that supports the shaft member in a radial direction with a lubricating oil film formed in a radial bearing gap between the inner peripheral surface of the bearing sleeve and the outer peripheral surface of the shaft member, and a shaft A thrust bearing part that supports one end of the member in the thrust direction, and a bottom gap that accommodates the thrust bearing part and is filled with lubricating oil. A gap is provided in the internal space of the housing, and the radial bearing gap Gap width of W1, radial When the gap width of the gap was W2, and satisfies a relationship of 30 × W1 ≦ W2 ≦ 250 × W1.

　このようにハウジングの内部空間に空隙部を設けることで、ハウジングの内部空間に充填する潤滑油量が、上記内部空間の全容積よりも少なくなり、上記内部空間に潤滑油で満たされていない領域が設けられる。よって、ハウジングの内周に軸受スリーブ及び環状部材を固定した後であって、軸受スリーブ内周への軸部材の挿入前に、適当な給油具（例えばマイクロピペット）を用いて内部空間に潤滑油を注入するだけで、内部空間に必要量の潤滑油を介在させることができる。従って、注油のための大掛かりな設備や高精密な油面の調整及び管理作業が不要となり、流体動圧軸受装置の製造コストを低廉化することができる。 Thus, by providing a gap in the internal space of the housing, the amount of lubricating oil that fills the internal space of the housing is less than the total volume of the internal space, and the internal space is not filled with lubricating oil. Is provided. Therefore, after the bearing sleeve and the annular member are fixed to the inner periphery of the housing and before the shaft member is inserted into the inner periphery of the bearing sleeve, the lubricating oil is lubricated in the inner space using an appropriate oil supply tool (for example, a micropipette). The required amount of lubricating oil can be interposed in the internal space simply by injecting. Therefore, large-scale equipment for lubrication and highly precise oil level adjustment and management work are not required, and the manufacturing cost of the fluid dynamic bearing device can be reduced.

　また、ラジアル軸受隙間の隙間幅をＷ１、径方向隙間の隙間幅をＷ２としたとき、３０×Ｗ１≦Ｗ２≦２５０×Ｗ１の関係式を満たすように、ラジアル軸受隙間の隙間幅と径方向隙間の隙間幅をそれぞれ設定することにより、軸部材の挿入に伴う環状部材の内周面への潤滑油の付着が可及的に防止される。従って、組立て時の潤滑油漏れを可及的に防止することが可能となり、これにより、流体動圧軸受装置への注油、ひいては流体動圧軸受装置の組立てを簡便かつ低コストに実行可能としている。 In addition, when the clearance width of the radial bearing clearance is W1 and the clearance width of the radial clearance is W2, the clearance width of the radial bearing clearance and the radial clearance so as to satisfy the relational expression of 30 × W1 ≦ W2 ≦ 250 × W1. By setting each of the gap widths, it is possible to prevent the lubricant from adhering to the inner peripheral surface of the annular member as the shaft member is inserted as much as possible. Accordingly, it is possible to prevent leakage of lubricating oil during assembly as much as possible, and thereby, it is possible to perform lubrication to the fluid dynamic bearing device, and consequently assembly of the fluid dynamic bearing device, simply and at low cost. .

特開２００３－３０７２１２号公報JP 2003-307212 A 特開２０１４－５９０１４号公報JP 2014-59014 A

　特許文献２に記載された技術は、所定量の潤滑油を注入した状態から挿脱自在な軸部材を挿入することにより、ラジアル軸受隙間や底隙間などハウジングの内部空間のうち最低限必要な部分に潤滑油を満たしてなる、いわばパーシャルフィル状態の含油構造を得るものである。従って、当該技術によれば、従来よりも少ない潤滑油でもって優れた軸受性能を発揮することが可能となる。一方で、この種の形態をなす流体動圧軸受装置においては、軸部材と環状部材との間の径方向隙間の大きさが問題となる。すなわち、上述のように、組立て時の潤滑油の漏れ出しを効果的に防止するためには、径方向隙間の隙間幅Ｗ２をラジアル軸受隙間Ｗ１の３０倍以上とする必要があるが、これだけ径方向隙間を大きくすると、ハウジングの内部空間のうち径方向隙間を介して大気に開放されている領域が大きくなるため、どうしても潤滑油の蒸発が問題となる。ましてや、上述のように特許文献２に記載の技術は、従来よりも潤滑油の注油量を少なくしているため、蒸発による潤滑油の消失は、軸受性能の低下に直結し易い。 The technique described in Patent Document 2 is the minimum required portion of the internal space of the housing, such as a radial bearing gap and a bottom gap, by inserting a shaft member that can be inserted and removed from a state where a predetermined amount of lubricating oil is injected. In other words, an oil-impregnated structure in a partial fill state, which is filled with lubricating oil, is obtained. Therefore, according to this technology, it is possible to exhibit excellent bearing performance with less lubricating oil than in the past. On the other hand, in the fluid dynamic bearing device having this type of configuration, the size of the radial gap between the shaft member and the annular member becomes a problem. That is, as described above, in order to effectively prevent leakage of the lubricating oil during assembly, it is necessary to set the gap width W2 of the radial gap to 30 times or more of the radial bearing gap W1. If the directional gap is increased, the area of the internal space of the housing that is open to the atmosphere via the radial gap becomes larger, which inevitably causes evaporation of the lubricating oil. In addition, as described above, since the technique described in Patent Document 2 reduces the amount of lubricating oil injected as compared with the prior art, the disappearance of the lubricating oil due to evaporation is likely to be directly linked to a decrease in bearing performance.

　以上の実情に鑑み、本発明では、組立て時における潤滑油の漏れ出しを防止しつつ、使用時における潤滑油の減少を可及的に抑制することにより、優れた軸受性能を長期にわたって発揮可能な流体動圧軸受装置を低コストに提供することを、解決すべき技術課題とする。 In view of the above circumstances, in the present invention, it is possible to exhibit excellent bearing performance over a long period of time by preventing leakage of lubricating oil during assembly and suppressing the decrease of lubricating oil during use as much as possible. Providing a fluid dynamic bearing device at low cost is a technical problem to be solved.

　前記課題の解決は、本発明に係る流体動圧軸受装置によって達成される。すなわち、この軸受装置は、軸方向一端が閉塞されると共に軸方向他端が開口している有底筒状のハウジングと、ハウジングの内周に配設された軸受スリーブと、挿脱可能に軸受スリーブの内周に挿入された軸部を有する軸部材と、ハウジングの他端開口側に位置し、軸部材の外周面との間に径方向隙間を形成する環状部と、軸受スリーブの内周面と軸部材の外周面との間のラジアル軸受隙間に形成される潤滑油の油膜で軸部材をラジアル方向に支持するラジアル軸受部と、軸部材の一端をスラスト方向に支持するスラスト軸受部と、スラスト軸受部を収容する底隙間とを備えた流体動圧軸受装置において、ハウジングの内部空間の一部が潤滑油で満たされており、かつ径方向隙間を含む残部が潤滑油で満たされていない空隙部であって、軸部材の外周面のうち軸受スリーブの内周面と対向する第一の部分の外径寸法より、環状部の内周面と対向する第二の部分の外径寸法のほうが大きい点をもって特徴付けられる。なお、ここでいう「スラスト軸受部」は、軸部材の一端をスラスト方向に接触支持するピボット軸受部であってもよいし、軸部材の一端を潤滑油の動圧でスラスト方向に非接触支持する動圧軸受部であってもよい。 The solution to the above problem is achieved by the fluid dynamic bearing device according to the present invention. That is, this bearing device includes a bottomed cylindrical housing that is closed at one end in the axial direction and opened at the other end in the axial direction, a bearing sleeve disposed on the inner periphery of the housing, and a removably-bearing bearing. A shaft member having a shaft portion inserted in the inner periphery of the sleeve, an annular portion located on the other end opening side of the housing and forming a radial clearance between the outer peripheral surface of the shaft member, and an inner periphery of the bearing sleeve A radial bearing portion that supports the shaft member in the radial direction with an oil film of lubricating oil formed in a radial bearing gap between the surface and the outer peripheral surface of the shaft member, and a thrust bearing portion that supports one end of the shaft member in the thrust direction In the fluid dynamic pressure bearing device having the bottom gap for accommodating the thrust bearing portion, a part of the inner space of the housing is filled with the lubricating oil, and the remaining portion including the radial gap is filled with the lubricating oil. No gap and shaft It is characterized by the fact that the outer diameter of the second portion facing the inner peripheral surface of the annular portion is larger than the outer diameter of the first portion facing the inner peripheral surface of the bearing sleeve of the outer peripheral surface of the material. . The “thrust bearing portion” referred to here may be a pivot bearing portion that contacts and supports one end of the shaft member in the thrust direction, or supports one end of the shaft member in the thrust direction by the dynamic pressure of the lubricating oil. It may be a hydrodynamic bearing.

　このように、本発明に係る流体動圧軸受装置では、ハウジングの内部空間の一部を潤滑油で満たした、いわばパーシャルフィルの形態をなす含油構造を採用しながら、軸部材の外径寸法を、組立て完了状態において軸受スリーブとの間でラジアル軸受隙間を形成する部分と、環状部との間で径方向隙間を形成する部分とで異ならせた。具体的には、軸部材の外周面のうちラジアル軸受隙間を形成する第一の部分の外径寸法よりも、径方向隙間を形成する第二の部分の外径寸法を大きくした。これにより、軸部材の軸受スリーブへの挿入時、軸部材の外周面の第一の部分と環状部との間に相対的に大きな径方向隙間（挿入時隙間）が形成されるので、軸部材の挿入に伴いハウジングの内部空間に残存している空気が挿入時隙間を通じてスムーズに排出される一方、潤滑油の環状部内面への付着は可及的に防止される。また、軸部材を挿入し終えた後、すなわち流体動圧軸受装置の組立てが完了した後、軸部材の外周面の第二の部分と環状部との間に径方向隙間が形成されるが、この径方向隙間は挿入時隙間に比べて相対的に小さいために、ハウジングの内部空間のうち径方向隙間を通じて大気に開放されている領域は縮小する。以上の作用より、本発明によれば、軸部材の挿入時における潤滑油の漏れ出しを効果的に防止しつつも、使用時における潤滑油の蒸発を可及的に抑制して、優れた軸受性能を長期にわたって発揮することが可能となる。また、軸部材の外径寸法を所定の領域間で異ならせただけの構成変更で済むため、大幅なコストアップを避けて量産することが可能となる。もちろん、本発明によれば、軸部材の挿入前に潤滑油を注入するだけで済むため、真空含浸などの大掛かりな設備を必要とする注油作業や高精密な油面の調整ないし管理作業が不要となる。また、注油量も上述の通り必要最小限で足りる。以上の点より、本発明に係る流体動圧軸受装置の製造コストを下げることが可能となる。 Thus, in the fluid dynamic pressure bearing device according to the present invention, the outer diameter of the shaft member is reduced while adopting an oil-impregnated structure in the form of a partial fill, in which a part of the inner space of the housing is filled with lubricating oil. In the assembled state, the radial bearing gap is formed with the bearing sleeve, and the radial gap is formed with the annular portion. Specifically, the outer diameter dimension of the second portion forming the radial clearance is made larger than the outer diameter dimension of the first portion forming the radial bearing gap in the outer peripheral surface of the shaft member. Thereby, when inserting the shaft member into the bearing sleeve, a relatively large radial clearance (gap at insertion) is formed between the first portion of the outer peripheral surface of the shaft member and the annular portion. As the air is inserted, the air remaining in the internal space of the housing is smoothly discharged through the gap during insertion, while adhesion of the lubricating oil to the inner surface of the annular portion is prevented as much as possible. Further, after the shaft member has been inserted, that is, after the assembly of the fluid dynamic bearing device is completed, a radial gap is formed between the second portion of the outer peripheral surface of the shaft member and the annular portion. Since this radial gap is relatively smaller than the insertion gap, the area open to the atmosphere through the radial gap in the internal space of the housing is reduced. As described above, according to the present invention, while effectively preventing leakage of the lubricating oil when the shaft member is inserted, the evaporation of the lubricating oil during use is suppressed as much as possible, and an excellent bearing The performance can be demonstrated over a long period of time. In addition, since it is only necessary to change the configuration by changing the outer diameter dimension of the shaft member between predetermined regions, mass production can be performed while avoiding a significant increase in cost. Of course, according to the present invention, it is only necessary to inject the lubricating oil before inserting the shaft member, so there is no need for oiling work that requires large-scale equipment such as vacuum impregnation or high-precision oil level adjustment or management work. It becomes. In addition, the required amount of oil is sufficient as described above. From the above points, the manufacturing cost of the fluid dynamic bearing device according to the present invention can be reduced.

　また、本発明に係る流体動圧軸受装置においては、軸受スリーブの内径寸法をｄ１、環状部の内径寸法をｄ２、軸部材の外周面のうち軸受スリーブとの間にラジアル軸受隙間を形成する第一の部分の外径寸法をｄ３、及び環状部との間に径方向隙間を形成する第二の部分の外径寸法をｄ４としたとき、１０×（ｄ１－ｄ３）≦ｄ２－ｄ４＜６０×（ｄ１－ｄ３）を満たしていてもよい。 In the fluid dynamic bearing device according to the present invention, the inner diameter dimension of the bearing sleeve is d1, the inner diameter dimension of the annular portion is d2, and a radial bearing gap is formed between the outer peripheral surface of the shaft member and the bearing sleeve. 10 × (d1−d3) ≦ d2−d4 <60, where d3 is the outer diameter of the first portion and d4 is the outer diameter of the second portion that forms a radial gap between the annular portion. X (d1-d3) may be satisfied.

　上述のように各部材の寸法を具体的に設定することにより、流体動圧軸受装置の組立て完了状態において、軸部材と環状部との径方向隙間の隙間幅が、ラジアル軸受隙間の隙間幅の３０倍未満となる。径方向隙間の隙間幅を上述の程度までに留めておけば、流体動圧軸受装置の使用時、ハウジングの内部空間に充填されている潤滑油の大気への蒸発を効果的に抑制して、潤滑油の減少を最小限に抑えることができる。従って、軸受性能の低下を防止して長期にわたって優れた軸受性能を発揮させることが可能となる。また、径方向隙間の隙間幅をラジアル軸受隙間の隙間幅の５倍以上にしておけば、組立て時、すなわち軸部材の挿入時に、軸部材と環状部とが干渉する事態を確実に防止できるので、組立て作業を円滑かつ安全に行うことが可能となる。 By setting the dimensions of each member specifically as described above, the clearance width of the radial clearance between the shaft member and the annular portion is equal to the clearance width of the radial bearing clearance in the assembled state of the fluid dynamic bearing device. Less than 30 times. If the gap width of the radial gap is kept to the above level, when using the fluid dynamic pressure bearing device, the evaporation of the lubricating oil filled in the internal space of the housing is effectively suppressed, Lubrication loss can be minimized. Accordingly, it is possible to prevent deterioration of the bearing performance and to exhibit excellent bearing performance over a long period of time. Further, if the clearance width of the radial clearance is set to be 5 times or more than the clearance width of the radial bearing clearance, the shaft member and the annular portion can be reliably prevented from interfering during assembly, that is, when the shaft member is inserted. Thus, the assembly work can be performed smoothly and safely.

　また、この場合、本発明に係る流体動圧軸受装置においては、６０×（ｄ１－ｄ３）≦ｄ２－ｄ３を満たしていてもよい。 In this case, the fluid dynamic bearing device according to the present invention may satisfy 60 × (d1-d3) ≦ d2-d3.

　上述のように各部材の寸法を設定することにより、流体動圧軸受装置の組立て時、より具体的には軸部材の挿入時において、軸部と環状部との径方向隙間（すなわち挿入時隙間）の隙間幅がラジアル軸受隙間の隙間幅の３０倍以上となる。ラジアル軸受隙間と径方向隙間とが上述のような関係を満たす場合、軸部材の挿入に伴う環状部材の内周面への潤滑油の付着が効果的に防止される。従って、組立て時の潤滑油漏れを安定して防止することが可能となる。 By setting the dimensions of the respective members as described above, the radial clearance between the shaft portion and the annular portion (that is, the insertion clearance) when the fluid dynamic bearing device is assembled, more specifically, when the shaft member is inserted. ) Is 30 times or more the radial width of the radial bearing gap. When the radial bearing gap and the radial gap satisfy the relationship as described above, adhesion of lubricating oil to the inner peripheral surface of the annular member accompanying insertion of the shaft member is effectively prevented. Accordingly, it is possible to stably prevent lubricating oil leakage during assembly.

　また、本発明に係る流体動圧軸受装置においては、軸部材が、軸部と、軸部より大径で、環状部との間に径方向隙間を形成する第二の部分が外周に設けられた大径部とを一体に有するものであってもよい。 In the fluid dynamic bearing device according to the present invention, the shaft member is provided on the outer periphery with the shaft portion and the second portion having a larger diameter than the shaft portion and forming a radial clearance between the annular portion. It may have a large diameter part.

　あるいは、軸部材が、軸部と、軸部の外周に配置され、環状部との間に径方向隙間を形成する第二の部分が外周に設けられた隙間形成部材とを有するものであってもよい。 Alternatively, the shaft member includes a shaft portion and a gap forming member that is disposed on the outer periphery of the shaft portion, and a second portion that forms a radial clearance between the annular portion and the annular portion. Also good.

　軸部と大径部とが一体化されていれば、軸部が軸受スリーブに対して位置決めされると同時に大径部の環状部に対する位置決めもなされる。従って、ラジアル軸受隙間を高精度に管理することで、径方向隙間も自動的に高精度に管理することが可能となる。また、軸部とは別に隙間形成部材を用意し、軸部の外周に配置した構成をとることで、軸部を単純形状として、より簡便に軸受スリーブへの挿入を行うことができる。また、径方向隙間の大きさのみを変更したい場合にも迅速かつ容易に対応することができる。 If the shaft portion and the large diameter portion are integrated, the shaft portion is positioned with respect to the bearing sleeve, and at the same time, the large diameter portion is positioned with respect to the annular portion. Therefore, by managing the radial bearing gap with high accuracy, the radial gap can also be automatically managed with high accuracy. Further, by preparing a gap forming member separately from the shaft portion and arranging it on the outer periphery of the shaft portion, the shaft portion can be made into a simple shape and can be more easily inserted into the bearing sleeve. Moreover, it is possible to respond quickly and easily to change only the size of the radial gap.

　また、本発明に係る流体動圧軸受装置においては、径方向隙間と底隙間とを連通させる連通路をさらに有し、連通路の少なくとも一部で空隙部が構成されていてもよい。 Further, the fluid dynamic bearing device according to the present invention may further include a communication path that allows the radial gap and the bottom gap to communicate with each other, and at least a part of the communication path may form a gap.

　このように構成すれば、内部空間に潤滑油を注入した後に、軸受スリーブの内周に軸部材を挿入した場合であっても、軸部材の挿入に伴って底隙間の側に押し込まれる空気を、連通路を介して大気に円滑に排出することができるので、軸部材の挿入に伴う潤滑油の外部漏洩を一層効果的に防止することができる。 According to this configuration, even when the shaft member is inserted into the inner periphery of the bearing sleeve after the lubricating oil is injected into the internal space, the air pushed into the bottom gap side as the shaft member is inserted Since it can be smoothly discharged to the atmosphere through the communication passage, external leakage of the lubricating oil accompanying insertion of the shaft member can be more effectively prevented.

　また、本発明に係る流体動圧軸受装置においては、軸受スリーブが、内部空孔に潤滑油を含浸させた多孔質体からなるものであってもよい。 In the fluid dynamic pressure bearing device according to the present invention, the bearing sleeve may be made of a porous body in which internal holes are impregnated with lubricating oil.

　このように軸受スリーブを多孔質体で形成し、その内部空孔に潤滑油を含浸させた構造とすれば、軸受スリーブの表面開孔からの潤滑油の滲み出しにより、ラジアル軸受隙間及び底隙間の双方を潤沢な潤滑油で満たすことができる。よって、ラジアル軸受部及びスラスト軸受部の軸受性能を安定的に維持することが可能となる。また、予め潤滑油を含浸させた状態の軸受スリーブをハウジングに固定できれば、その分ハウジングの内部空間に注入する潤滑油の量を少なくできる。よって、ハウジング内部への注油作業をより簡便に行うことが可能となる。 If the bearing sleeve is formed of a porous body and has a structure in which the internal voids are impregnated with the lubricating oil, the radial bearing gap and the bottom gap are caused by the seepage of the lubricating oil from the surface opening of the bearing sleeve. Both can be filled with abundant lubricating oil. Therefore, the bearing performance of the radial bearing portion and the thrust bearing portion can be stably maintained. Further, if the bearing sleeve impregnated with the lubricating oil in advance can be fixed to the housing, the amount of the lubricating oil injected into the internal space of the housing can be reduced accordingly. Therefore, it is possible to perform the lubrication work into the housing more simply.

　また、本発明に係る流体動圧軸受装置においては、潤滑油が、エステル系もしくはＰＡＯ系潤滑油であってもよい。 Also, in the fluid dynamic bearing device according to the present invention, the lubricating oil may be an ester-based or PAO-based lubricating oil.

　このように、エステル系もしくはＰＡＯ系の潤滑油を使用することで、流体動圧軸受装置１の使用時や輸送時における温度変化等に強い含油構造を得ることができる。 Thus, by using an ester-based or PAO-based lubricating oil, it is possible to obtain an oil-impregnated structure that is resistant to temperature changes during use and transportation of the fluid dynamic bearing device 1.

　以上の説明に係る流体動圧軸受装置は、上述のように、組立て時における潤滑油の漏れ出しを効果的に防止しつつ、使用時における潤滑油の減少を可及的に抑制することにより、優れた軸受性能を長期にわたって発揮可能とするものであるから、例えばこの流体動圧軸受装置を備えたモータとして好適に提供可能である。 As described above, the fluid dynamic bearing device according to the above description effectively suppresses the leakage of the lubricating oil during assembly and suppresses the reduction of the lubricating oil during use as much as possible. Since excellent bearing performance can be exhibited over a long period of time, for example, it can be suitably provided as a motor including this fluid dynamic pressure bearing device.

　以上より、本発明によれば、組立て時における潤滑油の漏れ出しを防止しつつ、使用時における潤滑油の減少を可及的に抑制することにより、優れた軸受性能を長期にわたって発揮可能な流体動圧軸受装置を低コストに提供することが可能となる。 As described above, according to the present invention, a fluid capable of exhibiting excellent bearing performance over a long period of time by preventing leakage of the lubricating oil during assembly and suppressing the reduction of the lubricating oil during use as much as possible. It becomes possible to provide a hydrodynamic bearing device at low cost.

本発明の一実施形態に係るファンモータの断面図である。It is sectional drawing of the fan motor which concerns on one Embodiment of this invention. 図１に示す流体動圧軸受装置の断面図である。It is sectional drawing of the fluid dynamic pressure bearing apparatus shown in FIG. 図２に示す軸受スリーブの断面図である。It is sectional drawing of the bearing sleeve shown in FIG. 図２に示す流体動圧軸受装置の要部拡大断面図である。It is a principal part expanded sectional view of the fluid dynamic pressure bearing apparatus shown in FIG. 図２に示す流体動圧軸受装置の組立て工程を示す図であり、この組立て工程の初期段階（注油時）を示す図である。It is a figure which shows the assembly process of the fluid dynamic pressure bearing apparatus shown in FIG. 2, and is a figure which shows the initial stage (at the time of oiling) of this assembly process. 図２に示す流体動圧軸受装置の組立て工程を示す図であり、この組立て工程の中間段階（軸部材の挿入時）を示す図である。It is a figure which shows the assembly process of the fluid dynamic pressure bearing apparatus shown in FIG. 2, and is a figure which shows the intermediate | middle stage (at the time of insertion of a shaft member) of this assembly process. 図５Ｂの軸部材挿入時におけるハウジングの要部拡大断面図である。It is a principal part expanded sectional view of the housing at the time of the shaft member insertion of FIG. 5B. 本発明の他の実施形態に係る流体動圧軸受装置の要部拡大断面図である。It is a principal part expanded sectional view of the fluid dynamic pressure bearing apparatus which concerns on other embodiment of this invention. 本発明の他の実施形態に係る流体動圧軸受装置の要部拡大断面図である。It is a principal part expanded sectional view of the fluid dynamic pressure bearing apparatus which concerns on other embodiment of this invention. 本発明の他の実施形態に係る流体動圧軸受装置の要部拡大断面図である。It is a principal part expanded sectional view of the fluid dynamic pressure bearing apparatus which concerns on other embodiment of this invention. 本発明の他の実施形態に係る流体動圧軸受装置の要部拡大断面図である。It is a principal part expanded sectional view of the fluid dynamic pressure bearing apparatus which concerns on other embodiment of this invention.

　以下、本発明の一実施形態を図面に基づき説明する。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

　図１は、本実施形態に係るファンモータの一構成例を概念的に示したものである。このファンモータは、流体動圧軸受装置１と、流体動圧軸受装置１の回転部となる軸部材２と、軸部材２が取付けられ、かつ図示しない羽根を有するロータ３と、ロータ３に取付けられるロータマグネット４と、ロータマグネット４と半径方向のギャップを介して対向するステータコイル５と、ステータコイル５が取付けられ、ファンモータの静止側を構成する保持部材としてのモータベース６とを備える。流体動圧軸受装置１のハウジング７は、モータベース６の内周に固定され、ロータ３は、流体動圧軸受装置１の軸部材２の一端に固定されている。このように構成されたファンモータにおいて、ステータコイル５に通電すると、ステータコイル５とロータマグネット４との間の電磁力でロータマグネット４が回転し、これに伴って軸部材２、および軸部材２に固定されたロータ３が一体に回転する。　 FIG. 1 conceptually shows a configuration example of a fan motor according to the present embodiment. The fan motor includes a fluid dynamic pressure bearing device 1, a shaft member 2 serving as a rotating portion of the fluid dynamic pressure bearing device 1, a rotor 3 to which the shaft member 2 is attached and having blades (not shown), and a rotor 3. A rotor magnet 4, a stator coil 5 facing the rotor magnet 4 via a radial gap, and a motor base 6 as a holding member to which the stator coil 5 is attached and which constitutes the stationary side of the fan motor. The housing 7 of the fluid dynamic bearing device 1 is fixed to the inner periphery of the motor base 6, and the rotor 3 is fixed to one end of the shaft member 2 of the fluid dynamic bearing device 1. In the fan motor configured as described above, when the stator coil 5 is energized, the rotor magnet 4 is rotated by the electromagnetic force between the stator coil 5 and the rotor magnet 4, and accordingly, the shaft member 2 and the shaft member 2 are rotated. The rotor 3 fixed to Rotates integrally. *

　なお、ロータ３が回転すると、ロータ３に設けられた羽根の形態に応じて図１中上向き又は下向きに風が送られる。このため、ロータ３の回転中にはこの送風作用の反力として、流体動圧軸受装置１の軸部材２に図１中下向き又は上向きの推力が作用する。ステータコイル５とロータマグネット４との間には、この推力を打ち消す方向の磁力（斥力）を作用させており、上記推力と磁力の大きさの差により生じたスラスト荷重が流体動圧軸受装置１のスラスト軸受部Ｔに作用する。上記推力を打ち消す方向の磁力は、例えば、ステータコイル５とロータマグネット４とを軸方向にずらして配置することにより発生させることができる（詳細な図示は省略）。また、ロータ３の回転時には、流体動圧軸受装置１の軸部材２にラジアル荷重が作用する。このラジアル荷重は、流体動圧軸受装置１のラジアル軸受部Ｒ１，Ｒ２に作用する。 When the rotor 3 rotates, wind is sent upward or downward in FIG. 1 according to the form of the blades provided on the rotor 3. For this reason, while the rotor 3 is rotating, a downward or upward thrust in FIG. 1 acts on the shaft member 2 of the fluid dynamic bearing device 1 as a reaction force of this air blowing action. A magnetic force (repulsive force) is applied between the stator coil 5 and the rotor magnet 4 in a direction to cancel out this thrust, and a thrust load generated by the difference between the thrust and the magnitude of the magnetic force is applied to the fluid dynamic bearing device 1. Acting on the thrust bearing portion T. The magnetic force in the direction to cancel the thrust can be generated, for example, by disposing the stator coil 5 and the rotor magnet 4 while being shifted in the axial direction (detailed illustration is omitted). Further, when the rotor 3 rotates, a radial load acts on the shaft member 2 of the fluid dynamic bearing device 1. This radial load acts on the radial bearing portions R1 and R2 of the fluid dynamic bearing device 1.

　図２は、本実施形態に係る流体動圧軸受装置１の断面図である。この流体動圧軸受装置１は、ハウジング７と、ハウジング７の内周に配設された軸受スリーブ８と、軸受スリーブ８の内周に挿入された軸部材２と、軸受スリーブ８よりもハウジング７の開口側でハウジング７の内周に固定された環状部材９とを主に備える。ここで、環状部材９が本発明に係る環状部に相当する。ハウジング７の内部空間には所定量の潤滑油１１（図２中、密な散点ハッチングで示す）が充填されており、少なくとも、軸部材２をラジアル方向に支持するラジアル軸受部Ｒ１，Ｒ２のラジアル軸受隙間Ｇｒ（図４を参照）と、軸部材２の下端をスラスト方向に支持するスラスト軸受部Ｔを収容した底隙間Ｇｂとが潤滑油１１で満たされている。なお、以下では、説明の便宜上、環状部材９が配置された側を上側、その軸方向反対側を下側とするが、使用時における流体動圧軸受装置１の姿勢を限定するものではない。 FIG. 2 is a cross-sectional view of the fluid dynamic bearing device 1 according to the present embodiment. This fluid dynamic bearing device 1 includes a housing 7, a bearing sleeve 8 disposed on the inner periphery of the housing 7, a shaft member 2 inserted on the inner periphery of the bearing sleeve 8, and the housing 7 rather than the bearing sleeve 8. And an annular member 9 fixed to the inner periphery of the housing 7 on the opening side. Here, the annular member 9 corresponds to an annular portion according to the present invention. The interior space of the housing 7 is filled with a predetermined amount of lubricating oil 11 (indicated by dense dotted hatching in FIG. 2), and at least the radial bearing portions R1 and R2 for supporting the shaft member 2 in the radial direction. The radial bearing gap Gr (see FIG. 4) and the bottom gap Gb that houses the thrust bearing portion T that supports the lower end of the shaft member 2 in the thrust direction are filled with the lubricating oil 11. In the following, for convenience of explanation, the side on which the annular member 9 is disposed is the upper side, and the opposite side in the axial direction is the lower side, but the posture of the fluid dynamic bearing device 1 in use is not limited.

　ハウジング７は、筒状部７ａと、筒状部７ａの下端側を閉塞する底部７ｂとを有する形状（いわゆる有底筒状）をなし、本実施形態では、図２に示すように筒状部７ａと底部７ｂが金属で一体に形成されている。筒状部７ａと底部７ｂの境界部内周には、筒状部７ａ及び底部７ｂと一体に段部７ｃが形成され、段部７ｃの上端面７ｃ１に軸受スリーブ８の下端面８ｂ（の外周側領域）が当接している。本実施形態では、ハウジング７の底部７ｂの内底面７ｂ１のスラスト軸受面となる領域に、例えば樹脂製のスラストプレート１０を配置している。これにより内底面７ｂ１（すなわちスラストプレート１０の上端面）が段部７ｃの上端面７ｃ１よりも所定高さ分だけ低くなるようにしている。ただし、このスラストプレート１０は必ずしも設ける必要はなく、省略しても構わない。その場合、底部７ｂの上端面がスラスト軸受面となる。もちろん、このハウジング７は樹脂の射出成形品とすることもできる。 The housing 7 has a shape (so-called bottomed tubular shape) having a tubular portion 7a and a bottom portion 7b that closes the lower end side of the tubular portion 7a. In this embodiment, as shown in FIG. 7a and the bottom 7b are integrally formed of metal. A step portion 7c is formed integrally with the cylindrical portion 7a and the bottom portion 7b on the inner periphery of the boundary portion between the cylindrical portion 7a and the bottom portion 7b, and the lower end surface 8b (outer peripheral side of the bearing sleeve 8 is formed on the upper end surface 7c1 of the step portion 7c. Area) is in contact. In the present embodiment, for example, a resin-made thrust plate 10 is disposed in a region serving as a thrust bearing surface of the inner bottom surface 7 b 1 of the bottom portion 7 b of the housing 7. Thus, the inner bottom surface 7b1 (that is, the upper end surface of the thrust plate 10) is set lower than the upper end surface 7c1 of the stepped portion 7c by a predetermined height. However, the thrust plate 10 is not necessarily provided and may be omitted. In that case, the upper end surface of the bottom 7b is a thrust bearing surface. Of course, the housing 7 may be a resin injection-molded product.

　軸部材２は、軸受スリーブ８の内周に挿入される軸部２ａを有する。この場合、軸部材２のうち少なくとも軸部２ａがステンレス鋼などの鋼材をはじめとする高剛性の金属材料で形成される。軸部２ａの外周面２ａ１は平滑な円筒面に形成されると共に、凸球面状の先端部２ａ２を除いて軸部２ａの全長にわたって外径寸法が一定となるように形成されている。この場合、軸部２ａの外周面２ａ１が本発明に係る第一の部分に相当する。軸部材２の外径寸法は、軸受スリーブ８および環状部材９の内径寸法よりも小径とされる。従って、軸部材２は、軸受スリーブ８および環状部材９に対して挿脱自在とされる。軸部２ａの先端部２ａ２は、ハウジング７の内底面７ｂ１（スラストプレート１０の上端面）と接触している。 The shaft member 2 has a shaft portion 2 a that is inserted into the inner periphery of the bearing sleeve 8. In this case, at least the shaft portion 2a of the shaft member 2 is formed of a highly rigid metal material including a steel material such as stainless steel. The outer peripheral surface 2a1 of the shaft portion 2a is formed in a smooth cylindrical surface, and is formed so that the outer diameter is constant over the entire length of the shaft portion 2a except for the convex spherical end portion 2a2. In this case, the outer peripheral surface 2a1 of the shaft portion 2a corresponds to a first portion according to the present invention. The outer diameter of the shaft member 2 is smaller than the inner diameter of the bearing sleeve 8 and the annular member 9. Therefore, the shaft member 2 can be inserted into and removed from the bearing sleeve 8 and the annular member 9. The tip 2a2 of the shaft 2a is in contact with the inner bottom surface 7b1 of the housing 7 (the upper end surface of the thrust plate 10).

　また、本実施形態では、軸部材２は、軸部２ａと、軸部２ａより大径で、軸部２ａが軸受スリーブ８の内周に挿入された状態において環状部材９との間に後述する径方向隙間Ｇａ（図４を参照）を形成する大径部２ｂとを一体に有する。この場合、大径部２ｂの外周面２ｂ１が本発明に係る第二の部分に相当する。径方向隙間Ｇａの詳細については後述する。 In the present embodiment, the shaft member 2 is described later between the shaft portion 2a and the annular member 9 in a state where the shaft portion 2a is inserted into the inner periphery of the bearing sleeve 8 and has a larger diameter than the shaft portion 2a. A large-diameter portion 2b that forms a radial gap Ga (see FIG. 4) is integrally provided. In this case, the outer peripheral surface 2b1 of the large diameter portion 2b corresponds to the second portion according to the present invention. Details of the radial gap Ga will be described later.

　軸受スリーブ８は、多孔質体、ここでは銅系粉末（純銅粉末だけでなく銅合金粉末を含む）あるいは鉄系粉末（純鉄粉末だけでなく鉄合金粉末を含む）を主成分とする焼結金属の多孔質体で円筒状に形成される。この場合、軸受スリーブ８の内部空孔には、潤滑油１１が含浸されている。軸受スリーブ８は、焼結金属以外の多孔質体、例えば多孔質樹脂で形成することもできる。この軸受スリーブ８は、その下端面８ｂをハウジング７の段部７ｃの上端面７ｃ１に当接させた状態でハウジング７に固定されている。これにより、ハウジング７と軸受スリーブ８の軸方向における相対的な位置決めがなされ、かつ軸受スリーブ８の下端面８ｂとハウジング７の内底面７ｂ１（スラストプレート１０の上端面）との間に所定容積の底隙間Ｇｂが形成される。 The bearing sleeve 8 is sintered mainly composed of a porous body, here, copper-based powder (including not only pure copper powder but also copper alloy powder) or iron-based powder (including not only pure iron powder but also iron alloy powder). It is formed in a cylindrical shape with a metal porous body. In this case, the internal holes of the bearing sleeve 8 are impregnated with the lubricating oil 11. The bearing sleeve 8 can also be formed of a porous body other than a sintered metal, for example, a porous resin. The bearing sleeve 8 is fixed to the housing 7 with its lower end surface 8 b in contact with the upper end surface 7 c 1 of the step 7 c of the housing 7. As a result, the housing 7 and the bearing sleeve 8 are relatively positioned in the axial direction, and a predetermined volume is provided between the lower end surface 8b of the bearing sleeve 8 and the inner bottom surface 7b1 of the housing 7 (upper end surface of the thrust plate 10). A bottom gap Gb is formed.

　軸受スリーブ８は、圧入（大きな締め代をもたせた圧入）、接着、圧入接着（圧入と接着の併用）等の適宜の手段でハウジング７の内周に固定し得るが、本実施形態では、環状部材９とハウジング７の底部７ｂ（の外径端に設けた段部７ｃ）とで軸受スリーブ８をその軸方向両側から挟持することにより、軸受スリーブ８をハウジング７の内周位置においてハウジング７に固定している。このようにすれば、環状部材９をハウジング７に固定するのと同時に、軸受スリーブ８をハウジング７に固定することができるので、部材同士の組み付けに要する手間を軽減することができる。また、軸受スリーブ８を、金属製とされる本実施形態のハウジング７の内周に大きな締め代をもって圧入すると、圧入に伴う軸受スリーブ８の変形が軸受スリーブ８の内周面８ａに及び、ラジアル軸受隙間Ｇｒの幅精度、ひいてはラジアル軸受部Ｒ１，Ｒ２の軸受性能に悪影響が及ぶ可能性があるが、上記の固定方法ではこのような弊害が可及的に防止される。さらには、軸受スリーブ８の内部空孔に予め潤滑油１１を含浸させておき、然る後、ハウジング７に固定する場合、接着固定だと、軸受スリーブ８の外周面８ｄから潤滑油１１が滲み出て、接着に支障を来すおそれがあるが、軸方向に挟持することでハウジング７に固定するのであれば、このような問題も生じない。 The bearing sleeve 8 can be fixed to the inner periphery of the housing 7 by appropriate means such as press-fitting (press-fitting with a large tightening allowance), adhesion, press-fitting adhesion (combination of press-fitting and adhesion). The bearing sleeve 8 is clamped to the housing 7 at the inner peripheral position of the housing 7 by sandwiching the bearing sleeve 8 from both sides in the axial direction between the member 9 and the bottom portion 7b of the housing 7 (the stepped portion 7c provided at the outer diameter end thereof). It is fixed. In this way, since the bearing sleeve 8 can be fixed to the housing 7 at the same time as the annular member 9 is fixed to the housing 7, the labor required for assembling the members can be reduced. Further, when the bearing sleeve 8 is press-fitted into the inner periphery of the housing 7 of the present embodiment made of metal with a large allowance, the deformation of the bearing sleeve 8 due to the press-fitting extends to the inner peripheral surface 8a of the bearing sleeve 8 and radial. Although the width accuracy of the bearing gap Gr, and thus the bearing performance of the radial bearing portions R1 and R2, may be adversely affected, the above-described fixing method prevents such an adverse effect as much as possible. Further, when the internal hole of the bearing sleeve 8 is impregnated with the lubricating oil 11 in advance and then fixed to the housing 7, if the adhesive is fixed, the lubricating oil 11 oozes from the outer peripheral surface 8 d of the bearing sleeve 8. Although there is a possibility that the adhesion may be hindered, such a problem does not occur if the housing 7 is fixed by being held in the axial direction.

　軸受スリーブ８の内周面８ａには、対向する軸部２ａの外周面２ａ１との間にラジアル軸受隙間Ｇｒ（図４を参照）を形成する円筒状のラジアル軸受面が軸方向の二箇所に設けられる。図３に示すように、各ラジアル軸受面には、ラジアル軸受隙間内の潤滑油１１に動圧作用を発生させるための動圧発生部（ラジアル動圧発生部）Ａ１，Ａ２がそれぞれ形成されている。本実施形態のラジアル動圧発生部Ａ１，Ａ２は、それぞれ、互いに反対方向に傾斜し、かつ軸方向に離間して設けられた複数の上側動圧溝Ａａ１および下側動圧溝Ａａ２と、両動圧溝Ａａ１，Ａａ２を区画する凸状の丘部とを有し、全体としてヘリングボーン形状を呈する。本実施形態の丘部は、周方向で隣り合う動圧溝間に設けられた傾斜丘部Ａｂと、上下の動圧溝Ａａ１，Ａａ２間に設けられ、傾斜丘部Ａｂと略同径の環状丘部Ａｃとからなる。 A cylindrical radial bearing surface that forms a radial bearing gap Gr (see FIG. 4) between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the opposed shaft portion 2a is provided at two axial positions. Provided. As shown in FIG. 3, dynamic pressure generating portions (radial dynamic pressure generating portions) A1 and A2 for generating a dynamic pressure action on the lubricating oil 11 in the radial bearing gap are formed on each radial bearing surface. Yes. The radial dynamic pressure generating parts A1 and A2 of the present embodiment are each provided with a plurality of upper dynamic pressure grooves Aa1 and lower dynamic pressure grooves Aa2 that are inclined in opposite directions and spaced apart in the axial direction. It has convex hills that define the dynamic pressure grooves Aa1 and Aa2, and has a herringbone shape as a whole. The hill part of this embodiment is provided between the inclined hill part Ab provided between the dynamic pressure grooves adjacent in the circumferential direction, and the upper and lower dynamic pressure grooves Aa1 and Aa2, and has an annular shape substantially the same diameter as the inclined hill part Ab. It consists of hill part Ac.

　上側のラジアル動圧発生部Ａ１においては、上側の動圧溝Ａａ１の軸方向寸法が下側の動圧溝Ａａ２の軸方向寸法よりも大きくなっている。一方、下側のラジアル動圧発生部Ａ２においては、下側の動圧溝Ａａ２の軸方向寸法が上側の動圧溝Ａａ１の軸方向寸法よりも大きくなっている。さらに、ラジアル動圧発生部Ａ１を構成する上側の動圧溝Ａａ１の軸方向寸法は、ラジアル動圧発生部Ａ２を構成する下側の動圧溝Ａａ２の軸方向寸法と等しく、また、ラジアル動圧発生部Ａ１を構成する下側の動圧溝Ａａ２の軸方向寸法は、ラジアル動圧発生部Ａ２を構成する上側の動圧溝Ａａ１の軸方向寸法と等しくなっている。従って、軸部材２の回転時、上側（ラジアル軸受部Ｒ１）および下側（ラジアル軸受部Ｒ２）のラジアル軸受隙間Ｇｒ内の潤滑油１１は、それぞれ、下側および上側のラジアル軸受隙間に向けて押し込まれる。 In the upper radial dynamic pressure generating part A1, the axial dimension of the upper dynamic pressure groove Aa1 is larger than the axial dimension of the lower dynamic pressure groove Aa2. On the other hand, in the lower radial dynamic pressure generating part A2, the axial dimension of the lower dynamic pressure groove Aa2 is larger than the axial dimension of the upper dynamic pressure groove Aa1. Further, the axial dimension of the upper dynamic pressure groove Aa1 constituting the radial dynamic pressure generating part A1 is equal to the axial dimension of the lower dynamic pressure groove Aa2 constituting the radial dynamic pressure generating part A2, and the radial movement The axial dimension of the lower dynamic pressure groove Aa2 constituting the pressure generating part A1 is equal to the axial dimension of the upper dynamic pressure groove Aa1 constituting the radial dynamic pressure generating part A2. Accordingly, when the shaft member 2 rotates, the lubricating oil 11 in the upper (radial bearing portion R1) and lower (radial bearing portion R2) radial bearing gaps Gr is directed toward the lower and upper radial bearing gaps, respectively. Pushed in.

　なお、ラジアル動圧発生部Ａ１，Ａ２は、例えば、軸受スリーブ８を成形するのと同時に（詳細には、金属粉末を圧粉成形した後、焼結してなる焼結体にサイジング加工を施すことで仕上がり寸法の軸受スリーブ８を成形するのと同時に）型成形で形成してもよいし、焼結金属の良好な加工性に鑑み、内周面が平滑面に成形された軸受素材に転造等の塑性加工を施すことで形成してもよい。また、ラジアル動圧発生部Ａ１，Ａ２（各動圧溝）の形態はこれに限定されるものではない。例えば、ラジアル動圧発生部Ａ１，Ａ２の何れか一方又は双方は、スパイラル形状の動圧溝を円周方向に複数配列したものとしてもよい。また、ラジアル動圧発生部Ａ１，Ａ２の何れか一方又は双方は、対向する軸部２ａの外周面２ａ１に形成してもよい。 The radial dynamic pressure generating portions A1 and A2 are, for example, simultaneously formed with the bearing sleeve 8 (specifically, sizing the sintered body obtained by compacting and sintering metal powder. Thus, it may be formed by molding (simultaneously with the molding of the finished sleeve sleeve 8), or in view of the good workability of the sintered metal, it is transferred to a bearing material whose inner peripheral surface is formed into a smooth surface. You may form by performing plastic processing, such as fabrication. Moreover, the form of radial dynamic pressure generation part A1, A2 (each dynamic pressure groove) is not limited to this. For example, either one or both of the radial dynamic pressure generating portions A1 and A2 may have a plurality of spiral dynamic pressure grooves arranged in the circumferential direction. Further, either one or both of the radial dynamic pressure generating portions A1 and A2 may be formed on the outer peripheral surface 2a1 of the opposing shaft portion 2a.

　ハウジング７（の筒状部７ａ）の内周面７ａ１の上側領域には、図２に示すように、金属又は樹脂で円環状に形成された環状部材９が接着、圧入、圧入接着等の適宜の手段で固定される。環状部材９の内周面９ａと、これに対向する軸部材２の大径部２ｂの外周面２ｂ１との間には径方向隙間Ｇａが形成されており、軸受スリーブ８の上側は、この径方向隙間Ｇａを介して大気に開放されている。 In the upper region of the inner peripheral surface 7a1 of the housing 7 (the cylindrical portion 7a thereof), as shown in FIG. 2, an annular member 9 formed in a ring shape with metal or resin is appropriately bonded, press-fitted, press-fitted, or the like. It is fixed by means of A radial gap Ga is formed between the inner peripheral surface 9a of the annular member 9 and the outer peripheral surface 2b1 of the large-diameter portion 2b of the shaft member 2 facing this, and the upper side of the bearing sleeve 8 has this diameter. It is open to the atmosphere via the directional gap Ga.

　図４に拡大して示すように、径方向隙間Ｇａの隙間幅ｗ２は、ラジアル軸受部Ｒ１，Ｒ２（図４では上側のラジアル軸受部Ｒ１のみ図示している）のラジアル軸受隙間Ｇｒの隙間幅ｗ１よりも広く設定される。具体的には、軸受スリーブ８の内径寸法をｄ１、環状部材９の内径寸法をｄ２、軸部２ａの外周面２ａ１（第一の部分）の外径寸法をｄ３、及び大径部２ｂの外周面２ｂ１（第二の部分）の外径寸法をｄ４としたとき、１０×（ｄ１－ｄ３）≦ｄ２－ｄ４＜６０×（ｄ１－ｄ３）を満たすように、各部材の寸法が設定される。これを径方向隙間Ｇａの隙間幅ｗ２と、ラジアル軸受部Ｒ１（Ｒ２）の隙間幅ｗ１を用いて書き直すと、５×ｗ１≦ｗ２＜３０×ｗ１となる。 4, the gap width w2 of the radial gap Ga is a gap width of the radial bearing gap Gr of the radial bearing portions R1, R2 (only the upper radial bearing portion R1 is shown in FIG. 4). It is set wider than w1. Specifically, the inner diameter of the bearing sleeve 8 is d1, the inner diameter of the annular member 9 is d2, the outer diameter of the outer peripheral surface 2a1 (first portion) of the shaft portion 2a is d3, and the outer diameter of the large-diameter portion 2b. When the outer diameter of the surface 2b1 (second portion) is d4, the dimensions of each member are set so as to satisfy 10 × (d1-d3) ≦ d2-d4 <60 × (d1-d3). . When this is rewritten using the gap width w2 of the radial gap Ga and the gap width w1 of the radial bearing portion R1 (R2), 5 × w1 ≦ w2 <30 × w1.

　なお、ラジアル軸受隙間Ｇｒの隙間幅ｗ１は、必要とされる軸受性能に応じて適宜の大きさに設定され、通常数μｍ程度、より具体的には２～１０μｍに設定される（図４では、ラジアル軸受隙間Ｇｒの隙間幅ｗ１を誇張して描いている）。従って、例えばラジアル軸受隙間Ｇｒの隙間幅ｗ１が１０μｍに設定される場合、径方向隙間Ｇａの隙間幅ｗ２は、５０μｍ（０．０５ｍｍ）以上でかつ３００μｍ（０．３０ｍｍ）未満に設定される。　 The gap width w1 of the radial bearing gap Gr is set to an appropriate size according to the required bearing performance, and is usually set to about several μm, more specifically 2 to 10 μm (in FIG. 4). The gap width w1 of the radial bearing gap Gr is exaggerated). Therefore, for example, when the gap width w1 of the radial bearing gap Gr is set to 10 μm, the gap width w2 of the radial gap Ga is set to 50 μm (0.05 mm) or more and less than 300 μm (0.30 mm). *

　一方、上述のとおり、環状部材９は、軸受スリーブ８をハウジング７に対して固定するための固定部材としての機能も有することから、径方向隙間Ｇａの隙間幅ｗ２をあまりに大きく設定すると、環状部材９と軸受スリーブ８との接触面積が減少し、ハウジング７に対する軸受スリーブ８の固定力低下を招来する。ただし、ｗ２＜３０×ｗ１の関係式を満たすように各部材の寸法を設定すれば、固定力不足の問題は生じない。 On the other hand, as described above, since the annular member 9 also has a function as a fixing member for fixing the bearing sleeve 8 to the housing 7, if the gap width w2 of the radial gap Ga is set too large, the annular member 9 The contact area between the bearing sleeve 8 and the bearing sleeve 8 is reduced, and the fixing force of the bearing sleeve 8 against the housing 7 is reduced. However, if the dimension of each member is set so as to satisfy the relational expression of w2 <30 × w1, the problem of insufficient fixing force does not occur.

　また、軸部２ａの挿入に伴う環状部材９の内周面９ａへの潤滑油１１の付着を効果的に防止する観点からは、６０×（ｄ１－ｄ３）≦ｄ２－ｄ３を満たすように、各部材の寸法を設定するのがよい。効果については後述する。 Further, from the viewpoint of effectively preventing adhesion of the lubricating oil 11 to the inner peripheral surface 9a of the annular member 9 due to the insertion of the shaft portion 2a, so as to satisfy 60 × (d1-d3) ≦ d2-d3. The dimensions of each member should be set. The effect will be described later.

　流体動圧軸受装置１は、本実施形態では、径方向隙間Ｇａと底隙間Ｇｂとを連通させるための連通路１２を有する。連通路１２は、ハウジング７と軸受スリーブ８との間に形成され、一端が底隙間Ｇｂに開口した第１通路１２ａと、軸受スリーブ８と環状部材９との間に形成され、一端が径方向隙間Ｇａに開口すると共に他端が第１通路１２ａの他端につながった第２通路１２ｂとで構成される。ここでは、軸受スリーブ８の外周面８ｄに形成した一又は複数の軸方向溝８ｄ１とハウジング７（筒状部７ａ）の内周面７ａ１とで形成される軸方向の流体通路、および軸受スリーブ８の下端面８ｂに形成した一又は複数の径方向溝８ｂ１とハウジング７の段部上端面７ｃ１とで形成される径方向の流体通路で上記の第１通路１２ａを構成している。また、軸受スリーブ８の上端面８ｃに形成した一又は複数の径方向溝８ｃ１と環状部材９の下端面９ｂとで形成される径方向の流体通路で、上記の第２通路１２ｂを構成している。 In this embodiment, the fluid dynamic bearing device 1 has a communication path 12 for communicating the radial gap Ga and the bottom gap Gb. The communication passage 12 is formed between the housing 7 and the bearing sleeve 8, and is formed between the first passage 12 a having one end opened in the bottom gap Gb, the bearing sleeve 8 and the annular member 9, and one end is in the radial direction. The second passage 12b is open to the gap Ga and has the other end connected to the other end of the first passage 12a. Here, an axial fluid passage formed by one or a plurality of axial grooves 8d1 formed on the outer peripheral surface 8d of the bearing sleeve 8 and the inner peripheral surface 7a1 of the housing 7 (tubular portion 7a), and the bearing sleeve 8 The first passage 12a is constituted by a radial fluid passage formed by one or a plurality of radial grooves 8b1 formed in the lower end surface 8b and the stepped upper end surface 7c1 of the housing 7. The second passage 12b is configured by a radial fluid passage formed by one or more radial grooves 8c1 formed on the upper end surface 8c of the bearing sleeve 8 and the lower end surface 9b of the annular member 9. Yes.

　以上の構成を有する流体動圧軸受装置１が図２に示す姿勢で配置された状態では、ハウジング７の内部空間のうち、少なくともラジアル軸受部Ｒ１，Ｒ２のラジアル軸受隙間Ｇｒ及びスラスト軸受部Ｔを収容した底隙間Ｇｂを含む一部の領域が潤滑油１１で満たされる。本実施形態では、さらに、軸受スリーブ８の下端面８ｂに形成した径方向溝８ｂ１、軸受スリーブ８の下端外周チャンファで形成される環状空間、および軸受スリーブ８の上端内周チャンファと軸部２ａの外周面２ａ１との間に形成される径方向隙間（環状空間）も潤滑油１１で満たされる（図２を参照）。一方、ハウジング７の内部空間のうち、連通路１２の一部を含む残部の領域（上述した一部の領域を除いた領域）は潤滑油１１で満たされていない。具体的には、軸受スリーブ８の外周面８ｄに形成した軸方向溝８ｄ１（第１通路１２ａの一部）、軸受スリーブ８の上端外周チャンファで形成される環状空間、軸受スリーブ８の上端面８ｃに形成した径方向溝８ｃ１（第２通路１２ｂ）、及び径方向隙間Ｇａが潤滑油１１で満たされていない。 In the state where the fluid dynamic bearing device 1 having the above configuration is arranged in the posture shown in FIG. 2, at least the radial bearing gaps Gr and the thrust bearing portions T of the radial bearing portions R1 and R2 in the internal space of the housing 7 are provided. Part of the region including the accommodated bottom gap Gb is filled with the lubricating oil 11. In the present embodiment, the radial groove 8b1 formed in the lower end surface 8b of the bearing sleeve 8, the annular space formed by the lower end outer chamfer of the bearing sleeve 8, and the upper end inner chamfer of the bearing sleeve 8 and the shaft portion 2a. A radial gap (annular space) formed between the outer peripheral surface 2a1 and the outer circumferential surface 2a1 is also filled with the lubricating oil 11 (see FIG. 2). On the other hand, in the internal space of the housing 7, the remaining region including a part of the communication passage 12 (the region excluding the part of the region described above) is not filled with the lubricating oil 11. Specifically, the axial groove 8d1 (a part of the first passage 12a) formed on the outer peripheral surface 8d of the bearing sleeve 8, the annular space formed by the upper end outer chamfer of the bearing sleeve 8, the upper end surface 8c of the bearing sleeve 8 The radial groove 8 c 1 (second passage 12 b) and the radial gap Ga formed in are not filled with the lubricating oil 11.

　以上より、この流体動圧軸受装置１では、ハウジング７の内部空間に充填される潤滑油１１の量（体積）が、ハウジング７の内部空間の容積よりも少なくなっており、従って、この流体動圧軸受装置１（ハウジング７）の内部空間には潤滑油１１が介在しない空隙部が設けられている。本実施形態では、連通路１２の一部と径方向隙間Ｇａとで空隙部が構成されている。 As described above, in this fluid dynamic pressure bearing device 1, the amount (volume) of the lubricating oil 11 filled in the internal space of the housing 7 is smaller than the volume of the internal space of the housing 7. In the internal space of the pressure bearing device 1 (housing 7), a gap portion where no lubricating oil 11 is interposed is provided. In the present embodiment, a gap is formed by a part of the communication path 12 and the radial gap Ga.

　ここで、潤滑油１１としては、流体動圧軸受装置１の使用時や輸送時における温度変化等を考慮して、エステル系もしくはＰＡＯ系潤滑油が好適に使用される。 Here, as the lubricating oil 11, an ester-based or PAO-based lubricating oil is preferably used in consideration of a temperature change during use of the fluid dynamic bearing device 1 or transportation.

　以上の構成を具備する流体動圧軸受装置１は、以下のような手順で組み立てられる。 The fluid dynamic bearing device 1 having the above configuration is assembled in the following procedure.

　まず、内部空孔に潤滑油１１を含浸させた軸受スリーブ８を用意する。そして、この軸受スリーブ８の下端面８ｂがハウジング７の段部７ｃの上端面７ｃ１に当接するまで、軸受スリーブ８をハウジング７の内周に軽圧入もしくは隙間嵌めする。次いで、環状部材９を、その下端面９ｂを軸受スリーブ８の上端面８ｃに当接させた状態でハウジング７の内周面７ａ１の上端部に固定し、軸受スリーブ８を、環状部材９とハウジング７の底部７ｂ（段部７ｃ）とで軸方向両側から挟持して、ハウジング７に固定する。このようにハウジング７と軸受スリーブ８、及び環状部材９がサブアセンブリされた状態で、ハウジング７の内部空間（例えば、軸受スリーブ８の内周）に所定量の潤滑油１１を充填する（図５Ａを参照）。そして、図５Ｂに示すように、環状部材９および軸受スリーブ８の内周に軸部２ａを挿入し、軸部２ａの先端部２ａ２をスラストプレート１０の上端面、すなわちハウジング７の底部７ｂの内底面７ｂ１に当接させると共に（図２を参照）、軸部材２の大径部２ｂの外周面２ｂ１を環状部材９の内周面９ａと対向させる（図４を参照）。これにより、図２に示す流体動圧軸受装置１が完成する。 First, the bearing sleeve 8 in which the internal holes are impregnated with the lubricating oil 11 is prepared. The bearing sleeve 8 is lightly press-fitted or fitted into the inner periphery of the housing 7 until the lower end surface 8 b of the bearing sleeve 8 abuts on the upper end surface 7 c 1 of the step 7 c of the housing 7. Next, the annular member 9 is fixed to the upper end portion of the inner peripheral surface 7a1 of the housing 7 with the lower end surface 9b abutting against the upper end surface 8c of the bearing sleeve 8, and the bearing sleeve 8 is fixed to the annular member 9 and the housing. 7 is fixed to the housing 7 by being sandwiched from both sides in the axial direction by the bottom portion 7b (step portion 7c). With the housing 7, the bearing sleeve 8, and the annular member 9 being subassembled in this manner, a predetermined amount of lubricating oil 11 is filled in the internal space of the housing 7 (for example, the inner periphery of the bearing sleeve 8) (FIG. 5A). See). Then, as shown in FIG. 5B, the shaft portion 2a is inserted into the inner periphery of the annular member 9 and the bearing sleeve 8, and the tip portion 2a2 of the shaft portion 2a is inserted into the upper end surface of the thrust plate 10, that is, the bottom portion 7b of the housing 7. While making it contact | abut to the bottom face 7b1 (refer FIG. 2), the outer peripheral surface 2b1 of the large diameter part 2b of the shaft member 2 is made to oppose the inner peripheral surface 9a of the annular member 9 (refer FIG. 4). Thereby, the fluid dynamic bearing device 1 shown in FIG. 2 is completed.

　以上の構成からなる流体動圧軸受装置１において、軸部材２が回転すると、軸受スリーブ８の内周面８ａの上下２箇所に離間して設けられたラジアル軸受面と、これに対向する軸部２ａの外周面２ａ１との間にラジアル軸受隙間Ｇｒ，Ｇｒがそれぞれ形成される。そして軸部材２の回転に伴い、両ラジアル軸受隙間Ｇｒ，Ｇｒに形成される油膜の圧力がラジアル動圧発生部Ａ１，Ａ２の動圧作用によって高められ、軸部材２をラジアル方向に非接触支持するラジアル軸受部Ｒ１，Ｒ２が軸方向の二箇所に形成される。これと同時に、ハウジング７の内底面７ｂ１（スラストプレート１０の上端面）で軸部材２をスラスト一方向に接触支持するスラスト軸受部Ｔが形成される。なお、図１を参照しながら説明したように、軸部材２には、これを下方（ハウジング７の底部７ｂ側）に押し付ける外力としての磁力を作用させている。従って、軸部材２が回転するのに伴って軸部材２が過度に浮上するのを、ひいては軸受スリーブ８の内周から抜脱するのを可及的に防止することができる。 In the fluid dynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, radial bearing surfaces that are spaced apart at two locations on the inner peripheral surface 8a of the bearing sleeve 8 and a shaft portion that faces the radial bearing surfaces are provided. Radial bearing gaps Gr and Gr are formed between the outer peripheral surface 2a1 of 2a. As the shaft member 2 rotates, the pressure of the oil film formed in the radial bearing gaps Gr and Gr is increased by the dynamic pressure action of the radial dynamic pressure generating portions A1 and A2, and the shaft member 2 is supported in a non-contact manner in the radial direction. Radial bearing portions R1 and R2 are formed at two locations in the axial direction. At the same time, a thrust bearing portion T that supports the shaft member 2 in one thrust direction is formed on the inner bottom surface 7b1 of the housing 7 (the upper end surface of the thrust plate 10). As described with reference to FIG. 1, the shaft member 2 is subjected to a magnetic force as an external force that presses the shaft member 2 downward (on the bottom 7 b side of the housing 7). Therefore, it is possible to prevent the shaft member 2 from floating excessively with the rotation of the shaft member 2 and, as a result, to be removed from the inner periphery of the bearing sleeve 8 as much as possible.

　以上で説明したように、本発明に係る流体動圧軸受装置１では、ハウジング７の内部空間の一部（ここではラジアル軸受隙間Ｇｒ及び底隙間Ｇｂなど）が潤滑油１１で満たされた状態（図２を参照）において、径方向隙間Ｇａを含むハウジング７の内部空間の残部を空隙部としている。これはすなわち、内部空間に充填されている潤滑油１１の量が、内部空間の全容積よりも少ないことを意味する。本発明に係る流体動圧軸受装置１では、軸部材２が、軸受スリーブ８（および環状部材９）に対して挿脱自在であることから、上述したように、ハウジング７の内周に軸受スリーブ８及び環状部材９を固定した後であって、軸受スリーブ８内周への軸部材２の挿入前に、適当な給油具を用いてハウジング７の内部空間に潤滑油１１を充填するだけで、ハウジング７の内部空間に必要量の潤滑油１１を介在させることができる。そのため、真空含浸など注油のための大掛かりな設備や高精密な油面の調整ないし管理作業が不要となり、流体動圧軸受装置１の製造コストを低廉化することができる。 As described above, in the fluid dynamic bearing device 1 according to the present invention, a part of the internal space of the housing 7 (here, the radial bearing gap Gr and the bottom gap Gb) is filled with the lubricating oil 11 ( In FIG. 2), the remaining part of the internal space of the housing 7 including the radial gap Ga is used as a gap. This means that the amount of the lubricating oil 11 filled in the internal space is smaller than the total volume of the internal space. In the fluid dynamic pressure bearing device 1 according to the present invention, since the shaft member 2 is detachable with respect to the bearing sleeve 8 (and the annular member 9), as described above, the bearing sleeve is provided on the inner periphery of the housing 7. After the shaft 8 and the annular member 9 are fixed and before the shaft member 2 is inserted into the inner periphery of the bearing sleeve 8, the lubricating oil 11 is simply filled in the internal space of the housing 7 using an appropriate oiling tool. A required amount of lubricating oil 11 can be interposed in the internal space of the housing 7. This eliminates the need for large-scale equipment for oiling such as vacuum impregnation and highly precise oil level adjustment or management work, thereby reducing the manufacturing cost of the fluid dynamic bearing device 1.

　また、本発明に係る流体動圧軸受装置１では、上述のように、ハウジング７の内部空間の一部を潤滑油１１で満たした、いわばパーシャルフィルの形態をなす含油構造を採用しながら、軸部材２の外径寸法を、組立て完了状態において軸受スリーブ８との間でラジアル軸受隙間Ｇｒを形成する第一の部分と、環状部材９との間で径方向隙間Ｇａを形成する第二の部分とで異ならせた。具体的には、ラジアル軸受隙間Ｇｒを形成する軸部２ａの外周面２ａ１の外径寸法ｄ３よりも、径方向隙間Ｇａを形成する大径部２ｂの外周面２ｂ１の外径寸法ｄ４を大きくした（図４を参照）。これにより、軸部２ａの軸受スリーブ８への挿入時、図６に示すように、軸部２ａの外周面２ａ１と環状部材９の内周面９ａとの間に相対的に大きな径方向隙間（挿入時隙間Ｇａ’）が形成されるので、軸部２ａの挿入に伴いハウジング７の内部空間に残存している空気が挿入時隙間Ｇａ’を通じてスムーズに排出される一方、潤滑油１１の環状部材９の内周面９ａへの付着は可及的に防止される。また、軸部２ａを挿入し終えた後、すなわち流体動圧軸受装置１の組立てが完了した後、軸部材２の大径部２ｂの外周面２ｂ１と環状部材９の内周面９ａとの間に径方向隙間Ｇａが形成されるが（図２及び図４を参照）、この径方向隙間Ｇａの隙間幅ｗ２は挿入時隙間Ｇａ’の隙間幅ｗ３に比べて相対的に小さいために、ハウジング７の内部空間のうち径方向隙間Ｇａを通じて大気に開放されている領域は縮小する。以上の作用より、本発明によれば、軸部材２の挿入時における潤滑油１１の漏れ出しを効果的に防止しつつも、使用時における潤滑油１１の蒸発を可及的に抑制して、優れた軸受性能を長期にわたって発揮することが可能となる。また、軸部材２の外径寸法を所定の領域間（軸部２ａと大径部２ｂとの間）で異ならせただけの構成変更で済むため、大幅なコストアップを避けて量産することが可能となる。もちろん、本発明によれば、軸部材２の挿入前に潤滑油１１を注入するだけで済むため、真空含浸などの大掛かりな設備を必要とする注油作業や高精密な油面の調整ないし管理作業が不要となる。また、注油量も上述の通り必要最小限で足りる。以上の点より、本発明に係る流体動圧軸受装置１の製造コストを下げることが可能となる。　 Further, in the fluid dynamic bearing device 1 according to the present invention, as described above, while adopting an oil-impregnated structure in the form of a partial fill in which a part of the internal space of the housing 7 is filled with the lubricating oil 11, The outer diameter of the member 2 is set such that the first portion that forms the radial bearing gap Gr with the bearing sleeve 8 in the assembled state and the second portion that forms the radial gap Ga with the annular member 9. And made it different. Specifically, the outer diameter d4 of the outer peripheral surface 2b1 of the large-diameter portion 2b that forms the radial gap Ga is made larger than the outer diameter d3 of the outer peripheral surface 2a1 of the shaft portion 2a that forms the radial bearing gap Gr. (See FIG. 4). Thus, when the shaft portion 2a is inserted into the bearing sleeve 8, a relatively large radial clearance (see FIG. 6) is provided between the outer peripheral surface 2a1 of the shaft portion 2a and the inner peripheral surface 9a of the annular member 9. Since the insertion gap Ga ′) is formed, the air remaining in the inner space of the housing 7 with the insertion of the shaft portion 2a is smoothly discharged through the insertion gap Ga ′, while the annular member of the lubricating oil 11 9 is prevented as much as possible from adhering to the inner peripheral surface 9a. Further, after the insertion of the shaft portion 2 a, that is, after the assembly of the fluid dynamic bearing device 1 is completed, between the outer peripheral surface 2 b 1 of the large diameter portion 2 b of the shaft member 2 and the inner peripheral surface 9 a of the annular member 9. (See FIGS. 2 and 4), the gap width w2 of the radial gap Ga is relatively smaller than the gap width w3 of the insertion gap Ga ′. The area open to the atmosphere through the radial gap Ga in the internal space 7 is reduced. As described above, according to the present invention, while effectively preventing leakage of the lubricating oil 11 when the shaft member 2 is inserted, the evaporation of the lubricating oil 11 during use is suppressed as much as possible. Excellent bearing performance can be demonstrated over a long period of time. In addition, the configuration can be changed by simply changing the outer diameter dimension of the shaft member 2 between predetermined regions (between the shaft portion 2a and the large diameter portion 2b). It becomes possible. Of course, according to the present invention, it is only necessary to inject the lubricating oil 11 before the shaft member 2 is inserted, so that an oiling operation that requires a large facility such as vacuum impregnation or a highly precise oil surface adjustment or management operation is required. Is no longer necessary. In addition, the required amount of oil is sufficient as described above. From the above points, the manufacturing cost of the fluid dynamic bearing device 1 according to the present invention can be reduced. *

　なお、これら軸部２ａの外径寸法ｄ３と大径部２ｂの外径寸法ｄ４は、具体的には、軸受スリーブの内径寸法をｄ１、環状部の内径寸法をｄ２との間で、１０×（ｄ１－ｄ３）≦ｄ２－ｄ４＜６０×（ｄ１－ｄ３）を満たすように設定されるのがよい。この関係式を満たすように各部材（軸部材２、軸受スリーブ８、環状部材９）の寸法を具体的に設定することにより、流体動圧軸受装置１の組立て完了状態において、大径部２ｂと環状部材９との径方向隙間Ｇａの隙間幅ｗ２が、ラジアル軸受隙間Ｇｒの隙間幅ｗ１の３０倍未満となる。径方向隙間Ｇａの隙間幅ｗ２を上述の程度に留めておけば、流体動圧軸受装置１の使用時、ハウジング７の内部空間に充填されている潤滑油１１の大気への蒸発を効果的に抑制して、潤滑油１１の減少を最小限に抑えることができる。従って、軸受性能の低下を防止して長期にわたって優れた軸受性能を発揮させることが可能となる。また、径方向隙間Ｇａの隙間幅ｗ２をラジアル軸受隙間Ｇｒの隙間幅ｗ１の５倍以上にしておけば、組立て時、すなわち軸部２ａの挿入時に、軸部２ａないし大径部２ｂと環状部材９とが干渉する事態を確実に防止できるので、組立て作業を円滑かつ安全に行うことが可能となる。 Specifically, the outer diameter d3 of the shaft portion 2a and the outer diameter d4 of the large diameter portion 2b are 10 × between the inner diameter of the bearing sleeve d1 and the inner diameter of the annular portion d2. It is preferable to set so as to satisfy (d1-d3) ≦ d2-d4 <60 × (d1-d3). By specifically setting the dimensions of each member (the shaft member 2, the bearing sleeve 8, and the annular member 9) so as to satisfy this relational expression, in the assembly completion state of the fluid dynamic bearing device 1, The gap width w2 of the radial gap Ga with the annular member 9 is less than 30 times the gap width w1 of the radial bearing gap Gr. If the gap width w2 of the radial gap Ga is kept at the above-mentioned level, when the fluid dynamic bearing device 1 is used, the evaporation of the lubricating oil 11 filled in the internal space of the housing 7 to the atmosphere is effectively performed. It can suppress and the reduction | decrease of the lubricating oil 11 can be suppressed to the minimum. Accordingly, it is possible to prevent deterioration of the bearing performance and to exhibit excellent bearing performance over a long period of time. Further, if the gap width w2 of the radial gap Ga is set to be five times or more the gap width w1 of the radial bearing gap Gr, the shaft portion 2a or the large diameter portion 2b and the annular member are assembled during assembly, that is, when the shaft portion 2a is inserted. 9 can be surely prevented from interfering with 9, so that the assembling work can be performed smoothly and safely.

　また、本実施形態では、６０×（ｄ１－ｄ３）≦ｄ２－ｄ３を満たすように、軸部材２と軸受スリーブ８、及び環状部材９の寸法を設定した。これにより、流体動圧軸受装置１の組立て時、より具体的には軸部２ａの挿入時において、軸部２ａと環状部材９との径方向隙間、すなわち挿入時隙間Ｇａ’の隙間幅ｗ３（図６を参照）がラジアル軸受隙間Ｇｒの隙間幅ｗ１の３０倍以上となる。軸部材２の挿入に伴いハウジング７の内部空間に残存する空気は圧縮されるために、例えば軸受スリーブ８の内周に注入した潤滑油１１は、ラジアル軸受隙間Ｇｒを通じて軸受外部側（図２でいえば上側）に押し出される向きの力を受ける。この際、挿入時隙間Ｇａ’の隙間幅ｗ３がラジアル軸受隙間Ｇｒの隙間幅ｗ１の３０倍以上の大きさを有していれば、環状部材９の内周面９ａへの潤滑油１１の付着が効果的に防止される。従って、組立て時の潤滑油漏れを安定して防止することができる。 In the present embodiment, the dimensions of the shaft member 2, the bearing sleeve 8, and the annular member 9 are set so as to satisfy 60 × (d1-d3) ≦ d2-d3. As a result, when the fluid dynamic bearing device 1 is assembled, more specifically, when the shaft portion 2a is inserted, the radial gap between the shaft portion 2a and the annular member 9, that is, the gap width w3 of the insertion gap Ga ′ ( 6) is 30 times or more the gap width w1 of the radial bearing gap Gr. Since the air remaining in the inner space of the housing 7 is compressed as the shaft member 2 is inserted, for example, the lubricating oil 11 injected into the inner periphery of the bearing sleeve 8 passes through the radial bearing gap Gr (see FIG. 2). In other words, it receives a force that pushes upward. At this time, if the gap width w3 of the insertion gap Ga ′ is 30 times or more the gap width w1 of the radial bearing gap Gr, the lubricant 11 adheres to the inner peripheral surface 9a of the annular member 9. Is effectively prevented. Therefore, it is possible to stably prevent lubricating oil leakage during assembly.

　さらに、本実施形態では、径方向隙間Ｇａと底隙間Ｇｂとを連通させる連通路１２を設けたので、ハウジング７の内部空間に潤滑油１１を注入した後に、軸受スリーブ８の内周に軸部材２を挿入した場合であっても、軸部材２の挿入に伴ってハウジング７の底部７ｂ側に押し込まれる空気を、連通路１２を介して大気に排出することができる。従って、軸部材２の挿入に伴う潤滑油１１の外部漏洩を一層効果的に防止することができる。 Further, in the present embodiment, the communication passage 12 that communicates the radial gap Ga and the bottom gap Gb is provided. Therefore, after the lubricating oil 11 is injected into the internal space of the housing 7, the shaft member is formed on the inner periphery of the bearing sleeve 8. Even when 2 is inserted, the air that is pushed into the bottom 7 b side of the housing 7 with the insertion of the shaft member 2 can be discharged to the atmosphere via the communication path 12. Therefore, the external leakage of the lubricating oil 11 accompanying the insertion of the shaft member 2 can be more effectively prevented.

　また、軸部材２には、軸部材２をハウジング７の底部７ｂ側に押し付ける（スラスト他方向に支持する）外力を作用させるようにしたので、軸部材２をスラスト両方向に支持することが可能となる。これにより、スラスト方向の支持精度（回転精度）を高めることができる。本実施形態では、上記外力を、磁力で与えるようにし、しかもこの磁力を、ハウジング７を内周に保持するモータベース６に設けられるステータコイル５と、ロータ３に設けられるロータマグネット４とを軸方向にずらして配置することによって与えるようにした。この種の流体動圧軸受装置１が組み込まれる各種モータは、ロータマグネット４とステータコイル５とを必須の構成部材として備える。従って、上記構成を採用すれば、上記外力を特段のコスト増を招くことなく安価に付与することができる。 Further, since the shaft member 2 is subjected to an external force that presses the shaft member 2 against the bottom 7b side of the housing 7 (supported in the thrust other direction), the shaft member 2 can be supported in both thrust directions. Become. Thereby, the support precision (rotation precision) of a thrust direction can be improved. In the present embodiment, the external force is applied by a magnetic force, and the magnetic force is applied to the stator coil 5 provided on the motor base 6 holding the housing 7 on the inner periphery and the rotor magnet 4 provided on the rotor 3 as an axis. It was given by shifting it in the direction. Various motors in which this type of fluid dynamic bearing device 1 is incorporated include a rotor magnet 4 and a stator coil 5 as essential constituent members. Therefore, if the said structure is employ | adopted, the said external force can be provided cheaply, without causing a special cost increase.

　なお、図示は省略するが、径方向隙間Ｇａを介しての潤滑油漏れを一層効果的に防止するため、径方向隙間Ｇａに隣接して大気に接した軸部材２の大径部２ｂの外周面２ｂ１や環状部材９の上端面に撥油膜を形成してもよい。 Although illustration is omitted, in order to more effectively prevent lubricating oil leakage through the radial gap Ga, the outer periphery of the large-diameter portion 2b of the shaft member 2 that is in contact with the atmosphere adjacent to the radial gap Ga. An oil repellent film may be formed on the upper surface of the surface 2b1 or the annular member 9.

　以上、本発明の一実施形態を説明したが、本発明に係る流体動圧軸受装置１及びその製造方法は上記例示の形態に限定されることなく、本発明の範囲内において任意の形態を採り得る。 Although one embodiment of the present invention has been described above, the fluid dynamic bearing device 1 and the manufacturing method thereof according to the present invention are not limited to the above-described exemplary forms, and can take any form within the scope of the present invention. obtain.

　例えば、上記実施形態では、環状部材９として、内径寸法ｄ２が一定の円筒状をなす内周面９ａを有するものを例示したが、もちろんこれ以外の形態をとることも可能である。図７はその一例（本発明の他の実施形態）に係る流体動圧軸受装置１の要部拡大断面図を示している。図７に示すように、この流体動圧軸受装置１は、環状部材９の内周構造が図２等に示す流体動圧軸受装置１のそれと相違している。具体的には、図７に示す環状部材９は、内径寸法が相対的に小さい小径内周面９ｃと、小径内周面９ｃに比べて内径寸法が大きい大径内周面９ｄとを有する。ここで、小径内周面９ｃが軸受スリーブ８から遠い側に配設され、大径内周面９ｄが軸受スリーブ８に近い側に配設される。小径内周面９ｃは大径部２ｂの外周面２ｂ１と対向し、大径内周面９ｄは軸部２ａの外周面２ａ１と対向する。よって、この場合、小径内周面９ｃと大径部２ｂの外周面２ｂ１とのラジアル方向隙間が本発明に係る径方向隙間Ｇａとなる。 For example, in the above embodiment, the annular member 9 is exemplified as having the cylindrical inner peripheral surface 9a having a constant inner diameter dimension d2, but it is of course possible to take other forms. FIG. 7: has shown the principal part expanded sectional view of the fluid dynamic pressure bearing apparatus 1 which concerns on the example (other embodiment of this invention). As shown in FIG. 7, the fluid dynamic bearing device 1 is different in the inner peripheral structure of the annular member 9 from that of the fluid dynamic bearing device 1 shown in FIG. Specifically, the annular member 9 shown in FIG. 7 has a small-diameter inner peripheral surface 9c having a relatively small inner diameter and a large-diameter inner peripheral surface 9d having a larger inner diameter than the small-diameter inner peripheral surface 9c. Here, the small-diameter inner peripheral surface 9 c is disposed on the side far from the bearing sleeve 8, and the large-diameter inner peripheral surface 9 d is disposed on the side close to the bearing sleeve 8. The small-diameter inner peripheral surface 9c faces the outer peripheral surface 2b1 of the large-diameter portion 2b, and the large-diameter inner peripheral surface 9d faces the outer peripheral surface 2a1 of the shaft portion 2a. Therefore, in this case, the radial clearance between the small-diameter inner peripheral surface 9c and the outer peripheral surface 2b1 of the large-diameter portion 2b is the radial clearance Ga according to the present invention.

　このように環状部材９及び軸部材２を構成することによっても、軸部材２の挿入時における潤滑油１１の漏れ出しを効果的に防止しつつ、使用時における潤滑油１１の蒸発を可及的に抑制して、優れた軸受性能を長期にわたって発揮することが可能となる。また、本構成によれば、環状部材９の大径内周面９ｄと軸部２ａの外周面２ａ１との間のラジアル方向隙間を潤滑油１１のバッファとして利用することもできるので、図２等に示す流体動圧軸受装置１に比べて温度変化に強い含油構造とすることができる。 By configuring the annular member 9 and the shaft member 2 in this way, the lubricant 11 can be evaporated during use as much as possible while effectively preventing leakage of the lubricant 11 when the shaft member 2 is inserted. It is possible to exhibit excellent bearing performance over a long period of time. Further, according to this configuration, the radial clearance between the large-diameter inner peripheral surface 9d of the annular member 9 and the outer peripheral surface 2a1 of the shaft portion 2a can also be used as a buffer for the lubricating oil 11, so FIG. Compared with the fluid dynamic pressure bearing device 1 shown in FIG.

　もちろん、大径部２ｂの外周面２ｂ１は小径内周面９ｃと対向するだけでなく、図８に示すように、大径内周面９ｄとも対向するように軸部材２を構成してもよい。このようにすれば、小径内周面９ｃとの間に隙間幅ｗ２が一定の径方向隙間Ｇａを容易に形成することができる。 Of course, the shaft member 2 may be configured so that the outer peripheral surface 2b1 of the large-diameter portion 2b not only opposes the small-diameter inner peripheral surface 9c but also opposes the large-diameter inner peripheral surface 9d as shown in FIG. . In this way, it is possible to easily form the radial gap Ga having a constant gap width w2 between the small-diameter inner peripheral surface 9c.

　また、軸部材２に関し、上記実施形態では、軸部材２を、軸部２ａと、軸部２ａよりも大径でハウジング７の上側に位置する大径部２ｂとで一体に構成した場合を例示したが、これ以外の構成をとることも可能である。図９はその一例に係る流体動圧軸受装置１の要部拡大断面図を示している。図９に示すように本実施形態に係る流体動圧軸受装置１は、軸部材２の上部構造において上記実施形態と相違している。具体的には、この軸部材２は、軸部２ａと、軸部２ａとは別体とされて軸部２ａの外周に配設される隙間形成部材２ｃとを有する。この隙間形成部材２ｃは、図示を省略するが、軸部２ａの軸受スリーブ８への挿入後に図９に示す位置に配置可能な構造となっており、好ましくは、軸部２ａの軸受スリーブ８への挿入完了後に、環状部材９と対向する位置に配設される。これにより、組立て完了状態においては、隙間形成部材２ｃの外周面２ｃ１は、環状部材９の内周面９ａとの間に径方向隙間Ｇａを形成している。 Moreover, regarding the shaft member 2, in the said embodiment, the case where the shaft member 2 was integrally comprised by the shaft part 2a and the large diameter part 2b larger diameter than the shaft part 2a and located on the upper side of the housing 7 is illustrated. However, other configurations are possible. FIG. 9 shows an enlarged cross-sectional view of a main part of the fluid dynamic bearing device 1 according to the example. As shown in FIG. 9, the fluid dynamic bearing device 1 according to this embodiment is different from the above embodiment in the upper structure of the shaft member 2. Specifically, the shaft member 2 includes a shaft portion 2a and a gap forming member 2c that is separated from the shaft portion 2a and disposed on the outer periphery of the shaft portion 2a. Although not shown, the gap forming member 2c has a structure that can be disposed at the position shown in FIG. 9 after the shaft portion 2a is inserted into the bearing sleeve 8, and preferably, to the bearing sleeve 8 of the shaft portion 2a. After the completion of the insertion, it is disposed at a position facing the annular member 9. Thus, in the assembled state, the outer peripheral surface 2c1 of the gap forming member 2c forms a radial gap Ga between the inner peripheral surface 9a of the annular member 9 and the outer peripheral surface 2c1.

　このように環状部材９と軸部材２を構成することによっても、軸部材２の挿入時における潤滑油１１の漏れ出しを効果的に防止しつつも、使用時における潤滑油１１の蒸発を可及的に抑制して、優れた軸受性能を長期にわたって発揮することが可能となる。なお、本実施形態では、環状部材９の下端面９ｂと軸受スリーブ８の上端面８ｃは接触しておらず、軸受スリーブ８の外周面８ｄがハウジング７の内周面７ａ１に固定されている。また、環状部材９はその外周に設けた外周突出部９ｅをハウジング７の内周面７ａ１とその上端に設けた小径面７ａ２との段部に係合させることで、ハウジング７に固定している。 By configuring the annular member 9 and the shaft member 2 in this way, it is possible to effectively evaporate the lubricant 11 during use while effectively preventing leakage of the lubricant 11 when the shaft member 2 is inserted. Therefore, excellent bearing performance can be exhibited over a long period of time. In this embodiment, the lower end surface 9 b of the annular member 9 and the upper end surface 8 c of the bearing sleeve 8 are not in contact with each other, and the outer peripheral surface 8 d of the bearing sleeve 8 is fixed to the inner peripheral surface 7 a 1 of the housing 7. Further, the annular member 9 is fixed to the housing 7 by engaging an outer peripheral protruding portion 9e provided on the outer periphery thereof with a step portion of an inner peripheral surface 7a1 of the housing 7 and a small diameter surface 7a2 provided on the upper end thereof. .

　また、上記実施形態では、スラスト軸受部Ｔとしてピボット軸受部を採用した場合を例示したが、もちろん、これ以外の形態を採用することも可能である。図１０はその一例に係る流体動圧軸受装置１の断面図を示している。この流体動圧軸受装置１は、スラスト軸受部Ｔをいわゆる動圧軸受で構成している。この場合、軸部材２の先端（下端）には、軸部２ａの中心線と直交する向きに広がる平坦面２ａ３が設けられている。そして、図示は省略するが、軸部材２の平坦面２ａ３及びこれに対向するハウジング７の底部７ｂの内底面７ｂ１の何れか一方には、動圧溝等の動圧発生部（スラスト動圧発生部）が形成される。 In the above embodiment, the case where the pivot bearing portion is employed as the thrust bearing portion T is exemplified, but it is needless to say that other forms can be employed. FIG. 10 shows a cross-sectional view of the fluid dynamic bearing device 1 according to the example. In the fluid dynamic pressure bearing device 1, the thrust bearing portion T is constituted by a so-called dynamic pressure bearing. In this case, the front end (lower end) of the shaft member 2 is provided with a flat surface 2a3 extending in a direction orthogonal to the center line of the shaft portion 2a. And although illustration is abbreviate | omitted, any one of the flat surface 2a3 of the shaft member 2 and the inner bottom face 7b1 of the bottom part 7b of the housing 7 which opposes this has dynamic pressure generating parts (thrust dynamic pressure generation | occurrence | production), such as a dynamic pressure groove Part) is formed.

　また、以上で示した実施形態では、モータベース６の内周に、モータベース６と別体に設けたハウジング７を固定するようにしたが、ハウジング７にモータベース６に相当する部位を一体に設けることもできる。 In the embodiment described above, the housing 7 provided separately from the motor base 6 is fixed to the inner periphery of the motor base 6. However, a portion corresponding to the motor base 6 is integrated with the housing 7. It can also be provided.

　また、ラジアル軸受部Ｒ１，Ｒ２の何れか一方又は双方は、いわゆる多円弧軸受、ステップ軸受、および波型軸受等、公知のその他の動圧軸受で構成することもできる。また、スラスト軸受部Ｔを動圧軸受で構成する場合（図１０を参照）、この動圧軸受は、いわゆるステップ軸受や波型軸受等、公知のその他の動圧軸受で構成することもできる。 Further, either one or both of the radial bearing portions R1 and R2 can be configured by other known hydrodynamic bearings such as a so-called multi-arc bearing, a step bearing, and a wave bearing. Further, when the thrust bearing portion T is constituted by a dynamic pressure bearing (see FIG. 10), this dynamic pressure bearing can also be constituted by other known dynamic pressure bearings such as so-called step bearings and corrugated bearings.

　また、以上で示した実施形態では、ロータマグネット４とステータコイル５とを軸方向にずらして配置することにより、軸部材２に、軸部材２をハウジング７の底部７ｂ側に押し付けるための外力を作用させるようにしたが、このような外力を軸部材２に作用させるための手段は上記のものに限られない。図示は省略するが、例えば、ロータマグネット４を引き付け得る磁性部材をロータマグネット４と軸方向に対向配置することにより、上記磁力をロータ３に作用させることもできる。また、送風作用の反力としての推力が十分に大きく、この推力のみで軸部材２を下方に押し付けることができる場合、軸部材２を下方に押し付けるための外力としての磁力（磁気吸引力）は省略しても構わない。 In the embodiment described above, the rotor magnet 4 and the stator coil 5 are arranged so as to be shifted in the axial direction, whereby an external force for pressing the shaft member 2 against the bottom 7b side of the housing 7 is applied to the shaft member 2. Although it was made to act, the means for making such an external force act on the shaft member 2 is not restricted to the above. Although illustration is omitted, for example, the magnetic force can be applied to the rotor 3 by arranging a magnetic member that can attract the rotor magnet 4 so as to face the rotor magnet 4 in the axial direction. In addition, when the thrust as a reaction force of the air blowing action is sufficiently large and the shaft member 2 can be pressed downward only by this thrust, the magnetic force (magnetic attraction force) as an external force for pressing the shaft member 2 downward is It can be omitted.

　また、以上では、回転部材として、羽根を有するロータ３が軸部材２に固定される流体動圧軸受装置１に本発明を適用した場合について説明を行ったが、本発明は、回転部材として、ディスク搭載面を有するディスクハブ、あるいはポリゴンミラーが軸部材２に固定される流体動圧軸受装置１にも好ましく適用することができる。すなわち、本発明は、図１に示すようなファンモータのみならず、ディスク装置用のスピンドルモータや、レーザビームプリンタ（ＬＢＰ）用のポリゴンスキャナモータ等、その他の電気機器に組み込まれる流体動圧軸受装置１にも好ましく適用することができる。 In the above description, the case where the present invention is applied to the fluid dynamic bearing device 1 in which the rotor 3 having blades is fixed to the shaft member 2 as the rotating member has been described. The present invention can also be preferably applied to a disk hub having a disk mounting surface or a fluid dynamic bearing device 1 in which a polygon mirror is fixed to the shaft member 2. That is, the present invention is not only a fan motor as shown in FIG. 1, but also a fluid dynamic pressure bearing incorporated in other electrical equipment such as a spindle motor for a disk device and a polygon scanner motor for a laser beam printer (LBP). The present invention can also be preferably applied to the device 1.

Claims

　軸方向一端が閉塞されると共に軸方向他端が開口している有底筒状のハウジングと、前記ハウジングの内周に配設された軸受スリーブと、挿脱可能に前記軸受スリーブの内周に挿入された軸部を有する軸部材と、前記ハウジングの一端開口側に位置し、前記軸部材の外周面との間に径方向隙間を形成する環状部と、前記軸受スリーブの内周面と前記軸部材の外周面との間のラジアル軸受隙間に形成される潤滑油の油膜で前記軸部材をラジアル方向に支持するラジアル軸受部と、前記軸部材の一端をスラスト方向に支持するスラスト軸受部と、前記スラスト軸受部を収容する底隙間とを備えた流体動圧軸受装置において、
　前記ハウジングの内部空間の一部が潤滑油で満たされており、かつ前記径方向隙間を含む残部が潤滑油で満たされていない空隙部であって、
　前記軸部材の外周面のうち前記軸受スリーブの内周面と対向する第一の部分の外径寸法よりも、前記環状部の内周面と対向する第二の部分の外径寸法のほうが大きいことを特徴とする流体動圧軸受装置。 A bottomed cylindrical housing that is closed at one end in the axial direction and opened at the other end in the axial direction, a bearing sleeve disposed on the inner circumference of the housing, and an inner circumference of the bearing sleeve that can be inserted and removed. A shaft member having an inserted shaft portion, an annular portion that is located on one end opening side of the housing and forms a radial clearance between the shaft member and an outer peripheral surface of the shaft member; an inner peripheral surface of the bearing sleeve; A radial bearing portion that supports the shaft member in the radial direction with an oil film of a lubricating oil formed in a radial bearing gap between the outer peripheral surface of the shaft member, and a thrust bearing portion that supports one end of the shaft member in the thrust direction In the fluid dynamic bearing device provided with a bottom gap for accommodating the thrust bearing portion,
A part of the internal space of the housing is filled with lubricating oil, and the remaining part including the radial gap is a gap not filled with lubricating oil,
Of the outer peripheral surface of the shaft member, the outer diameter size of the second portion facing the inner peripheral surface of the annular portion is larger than the outer diameter size of the first portion facing the inner peripheral surface of the bearing sleeve. A fluid dynamic pressure bearing device.
　前記軸受スリーブの内径寸法をｄ１、前記環状部の内径寸法をｄ２、前記軸部材の外周面のうち前記軸受スリーブとの間に前記ラジアル軸受隙間を形成する第一の部分の外径寸法をｄ３、及び前記環状部との間に前記径方向隙間を形成する第二の部分の外径寸法をｄ４としたとき、
　１０×（ｄ１－ｄ３）≦ｄ２－ｄ４＜６０×（ｄ１－ｄ３）を満たしている請求項１に記載の流体動圧軸受装置。 The inner diameter dimension of the bearing sleeve is d1, the inner diameter dimension of the annular portion is d2, and the outer diameter dimension of the first portion that forms the radial bearing gap between the outer peripheral surface of the shaft member and the bearing sleeve is d3. And when the outer diameter of the second part forming the radial gap between the annular part is d4,
2. The fluid dynamic bearing device according to claim 1, wherein 10 × (d1-d3) ≦ d2-d4 <60 × (d1-d3) is satisfied.
　６０×（ｄ１－ｄ３）≦ｄ２－ｄ３を満たしている請求項２に記載の流体動圧軸受装置。 3. The fluid dynamic bearing device according to claim 2, wherein 60 × (d1-d3) ≦ d2-d3 is satisfied.
　前記軸部材は、前記軸部と、前記軸部より大径で、前記環状部との間に前記径方向隙間を形成する前記第二の部分が外周に設けられた大径部とを一体に有する請求項１～３の何れか一項に記載の流体動圧軸受装置。 The shaft member is integrally formed with the shaft portion and a large-diameter portion having a larger diameter than the shaft portion and the second portion forming the radial gap between the annular portion and provided on the outer periphery. The fluid dynamic bearing device according to any one of claims 1 to 3.
　前記軸部材は、前記軸部と、前記軸部の外周に配置され、前記環状部との間に前記径方向隙間を形成する前記第二の部分が外周に設けられた隙間形成部材とを有する請求項１～３の何れか一項に記載の流体動圧軸受装置。 The shaft member includes the shaft portion and a gap forming member that is disposed on an outer periphery of the shaft portion, and the second portion that forms the radial gap between the annular portion and the outer peripheral portion is provided on the outer periphery. The fluid dynamic bearing device according to any one of claims 1 to 3.
　前記径方向隙間と前記底隙間とを連通させる連通路をさらに有し、前記連通路の少なくとも一部で前記空隙部が構成されている請求項１～５の何れか一項に記載の流体動圧軸受装置。 The fluid dynamics according to any one of claims 1 to 5, further comprising a communication path that allows the radial gap and the bottom gap to communicate with each other, wherein the gap portion is configured by at least a part of the communication path. Pressure bearing device.
　前記軸受スリーブが、内部空孔に前記潤滑油を含浸させた多孔質体からなる請求項１～６の何れか一項に記載の流体動圧軸受装置。 The fluid dynamic bearing device according to any one of claims 1 to 6, wherein the bearing sleeve is made of a porous body in which internal holes are impregnated with the lubricating oil.
　前記潤滑油は、エステル系もしくはＰＡＯ系潤滑油である請求項１～７の何れか一項に記載の流体動圧軸受装置。 The fluid dynamic bearing device according to any one of claims 1 to 7, wherein the lubricating oil is an ester-based or PAO-based lubricating oil.
　請求項１～８の何れか一項に記載の流体動圧軸受装置を備えたモータ。 A motor comprising the fluid dynamic bearing device according to any one of claims 1 to 8.