JP3853169B2

JP3853169B2 - Hydrodynamic bearing device

Info

Publication number: JP3853169B2
Application number: JP2001096836A
Authority: JP
Inventors: 司高橋; 清隆菊地; 芳夫藤川; 寛哲徳永
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2001-03-29
Filing date: 2001-03-29
Publication date: 2006-12-06
Anticipated expiration: 2021-03-29
Also published as: JP2002295494A

Description

【０００１】
【発明の属する技術分野】
この発明は、ターボ分子ポンプやフライホイール等のたて形高速回転機械の高速回転される主軸を回転自在に支持する流体軸受装置に関するものである。
【０００２】
【従来の技術】
この種の流体軸受装置として、実開昭６３−９９０２５号公報に記載されたものが従来から知られている。この流体軸受装置は、図３に示すように、ハウジング２０に形成された油室２１の潤滑油中に軸受部材２２を浸漬し、その軸受部材２２の下面外周部を複数のボール２３で支持して、軸受部材２２の下面中央部と油室２１の底面中央部に設けられた突出部２４の上面間に微小なダンパ隙間２５を形成し、前記軸受部材２２の上面中央部上に配置された主軸２６の軸端を動圧軸受２７によって回転自在に支持している。
【０００３】
ここで、動圧軸受２７は、軸受部材２２の上面に凹形の半球状軸受面２７ａを形成し、一方、主軸２６の軸端に半球状表面２７ｂを設け、その半球状表面２７ｂと軸受面２７ａの少なくとも一方にスパイラル状の動圧発生溝２７ｃを設けている。
【０００４】
上記流体軸受装置においては、主軸２６の高速回転時に、動圧発生溝２７ｃのポンピング作用によって軸受面２７ａと半球状表面２７ｂ間の潤滑油の圧力を高め、その潤滑油の圧力により主軸２６を支持するようにしている。このため、主軸２６は軸受部材２２に対して非接触の状態で回転し、主軸２６をきわめて高速で回転させることができる。
【０００５】
また、軸受部材２２の下面と突出部２４の上面間に形成されたダンパ隙間２５内の潤滑油の剪断抵抗によるダンピング効果によって軸受部材２２が主軸２６の高速回転に伴って振動するのを防止することができるため、主軸２６を安定して高速回転させることができる。
【０００６】
ところで、流体軸受装置においては、主軸２６の高速回転によって動圧軸受部が発熱して温度上昇する。このとき、動圧軸受部の放熱による冷却が不充分であると、動圧軸受部の温度上昇により、動圧軸受部の潤滑油の粘度が低下し、動圧軸受部の負荷容量が減少する。
【０００７】
そのような不都合を解消するため、上記公報に記載された動圧軸受装置においては、軸受部材２２の下面と突出部２４の上面間に形成されたダンパ隙間２５の大きさを３０μｍ乃至２００μｍの範囲に管理し、動圧軸受部の熱を軸受部材２２からダンパ隙間２５を満たす潤滑油を介してハウジング２０の底面に熱伝導させて放熱し、動圧軸受部の温度上昇を抑制するようにしている。
【０００８】
しかしながら、ダンパ隙間２５は、軸受部材２２の下面中央部と油室２１の底面に設けられた突出部２４の上面間に設けられているため、面積の大きなダンパ隙間２５を確保することができず、軸受部材２２から突出部２４への熱伝導が不充分であって、動圧軸受部を効果的に冷却することができない。
【０００９】
また、ダンパ隙間２５の面積が小さいため、軸受部材２２の振動抑制に充分なダンピング効果を得ることができない。
【００１０】
そのような不都合を解消するため、図４に示す流体軸受装置が提案されている。この流体軸受装置においては、ハウジング３０の油室３１に収容された潤滑油中に円板状の軸受支持部材３２を浸漬し、その軸受支持部材３２の上面に設けられた嵌合孔３３内に軸受部材３４を嵌合して、ねじ３５の締付けにより外周部を固定し、前記軸受部材３４の上面中央部に設けられた突出部３４ａ上に主軸３６を配置して、その軸端部を動圧軸受３７により回転自在に支持している。
【００１１】
また、軸受支持部材３２の下面中央部にリング上のプレート３８を設け、そのプレート３８を複数のボール３９で支持して、軸受支持部材３２の下面外周部と油室３１の底部材４０の上面間にダンパ隙間４１を設けている。
【００１２】
上記流体軸受装置においては、軸受支持部材３２の下面外周部と底部材４０の上面間にダンパ隙間４１を設ける構成であるため、広い面積のダンパ隙間４１を確保することができる。このため、軸受部材３４から軸受支持部材３２に伝えられる熱を底部材４０に良好に熱伝導させることができると共に、ダンパ隙間４１の面積が大きいため、ダンピング効果に優れ、軸受部材３４の振動をより効果的に抑制することができる。
【００１３】
【発明が解決しようとする課題】
ところで、図４に示す流体軸受装置は、軸受支持部材３２からダンパ隙間を経由する放熱特性および軸受部材３４の振動を抑制するダンピング特性が優れているものの、軸受部材３４の外周は嵌合孔３３の内周に対して非接触であって、下面が軸受支持部材３２の嵌合孔３３の底面と接触するのみであり、その接触部と主軸３６の高速回転によって発熱し易い突出部３４ａ間の伝熱経路が長く、また、動圧軸受部が突出した形状であるので伝熱経路の断面積が小さい。そのため、熱伝導による突出部３４ａの冷却効果が悪く、動圧軸受３７の温度上昇を効果的に抑制することができない。
【００１４】
その結果、動圧軸受部の潤滑油が主軸の高速回転による温度上昇によって粘度が低下し、その粘度低下によって負荷容量が低減することになる。
【００１５】
この発明は、軸受部材と軸受支持部材間の伝熱特性を改善して動圧軸受部の冷却効果を高め、流体軸受装置の負荷容量の低減を防止することを課題としている。
【００１６】
【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、第１の発明においては、油室を有するハウジングと、前記油室の作動油中に浸漬された軸受支持部材と、その軸受支持部材の下面と油室の底面間に微小なダンパ隙間が形成されるよう軸受支持部材を支持する複数のボールと、前記軸受支持部材の上面中央部に形成された嵌合孔に嵌合された軸受部材とを有し、前記軸受部材の上面中央部に突出部を設け、その突出部上に設けられた主軸の軸端を動圧軸受によって回転自在に支持した流体軸受装置において、前記軸受支持部材の嵌合孔外周に、前記嵌合孔に嵌合された軸受部材の外周部よりも高い突出部を設け、前記軸受部材の突出部の熱を軸受支持部材に伝導する熱伝導率の高い熱伝導体を、前記軸受部材の突出部の外周と前記軸受支持部材の突出部との間に設けた構成を採用している。
【００１７】
上記のように、軸受支持部材の嵌合孔外周に、前記嵌合孔に嵌合された軸受部材の外周部よりも高い突出部を設け、前記軸受部材の突出部の熱を軸受支持部材に伝導する熱伝導率の高い熱伝導体を、前記軸受部材の突出部の外周と前記軸受支持部材の突出部との間に設けたことにより、前記軸受部材の突出部と軸受支持部材間の伝熱特性を高めることができ、軸受支持部材への熱伝導によって軸受部材の突出部を効果的に冷却することができる。
【００１８】
このため、動圧軸受部の潤滑油の粘度低下を防止し、負荷容量の低減を抑制することができる。
【００１９】
ここで、熱伝導体は、銅あるいはアルミニウム等の熱伝導率の高い金属で形成するのが好ましい。その熱伝導体の取付けに際し、熱伝導体をリング状とし、そのリング状熱伝導体を軸受部材の突出部の外周に圧入して下面を軸受支持部材の突出部の上面に当接させる方法を採用することができる。
【００２０】
前記リング状熱伝導体をインナーリングとその外側に嵌合したアウターリングとで形成し、インナーリングを軸受部材の突出部の外周に圧入して下面を軸受部材の上面外周部に接触させると共に、アウターリングを軸受支持部材の突出部の上面に接触させることにより、軸受部材と熱伝導体の接触面積を大きくとることができ、軸受部材の熱を熱伝導体に効果的に伝熱させることができ、熱伝導による軸受部材の冷却効果をより高めることができる。
【００２１】
【発明の実施の形態】
以下、この発明の実施の形態を図１乃至図２に基づいて説明する。図１に示すように、ハウジング１の底部２上に形成された油室３内には潤滑油が収容されている。
【００２２】
油室３の潤滑油中には円盤状の軸受支持部材４が浸漬されている。軸受支持部材４はアルミニウム合金等の軽合金によって形成されている。
【００２３】
前記油室３の底面には凹部５が形成され、その凹部５の底面と軸受支持部材４の下面には特殊鋼等の耐摩耗性に優れた金属から成るリング状のプレート６ａ、６ｂが対向位置に設けられ、そのプレート６ａ、６ｂ間に組込まれた複数のボール７により軸受支持部材４が支持されて、軸受支持部材４の下面と油室３の底面間に微小なダンパ隙間８が設けられている。
【００２４】
軸受支持部材４の上面中央部には嵌合孔９が形成され、その嵌合孔９内に軸受部材１０が嵌合され、ねじ１１の締付けによって外周部が軸受支持部材４に固定されている。軸受支持部材４の嵌合孔外周には、嵌合孔９に嵌合された軸受部材１０の外周部よりも高い突出部４ａが設けられている。
【００２５】
軸受部材１０は銅合金によって形成されている。この軸受部材１０は、上面中央部に突出部１０ａを有し、その突出部１０ａ上に設けられた主軸１２は動圧軸受１３によって回転自在に支持されている。動圧軸受１３は、突出部１０ａの上面に凹形の半球状軸受面１３ａを形成し、一方、主軸１２の軸端に半球状表面１３ｂを設け、その半球状表面１３ｂにスパイラル溝から成る動圧発生溝１３ｃを形成している。
【００２６】
なお、動圧発生溝１３ｃは軸受面１３ａにのみ形成してもよく、あるいは軸受面１３ａと半球状表面１３ｂの両方に形成してもよい。
【００２７】
軸受部材１０の突出部１０ａと軸受支持部材４との間には、突出部１０ａの熱を軸受支持部材４に伝導する熱伝導体１４が設けられている。
【００２８】
熱伝導体１４は銅やアルミニウム等の熱伝導率の高い金属を素材としている。この熱伝導体１４はリング状をなし、突出部１０ａの外周に圧入され、下面の外周部が軸受支持部材４の上面に接触している。
【００２９】
上記のように、軸受部材１０の突出部１０ａの外周に圧入した熱伝導体１４の下面外周部を軸受支持部材４の突出部４ａの上面に接触させることにより、主軸１２の高速回転により動圧軸受部が発熱して突出部１０ａが温度上昇すると、その熱は熱伝導体１４から軸受支持部材４に良好に伝導される。その熱伝導による放熱により突出部１０ａが冷却される。
【００３０】
このため、動圧軸受部の軸受面１３ａと半球状表面１３ｂ間の潤滑油の温度上昇による粘度の低下を防止し、動圧軸受部の負荷容量の低減を抑制することができる。
【００３１】
ここで、実施形態で示すように、軸受部材１０を銅合金で形成すると、主軸１２の接触回転時における摺動性を高めることができると共に、動圧軸受部に異物が侵入した際、その異物は軸受面１３ａに埋没され、異物のかみ込みによる回転特性の低下を抑制することができる。
【００３２】
また、銅合金製軸受部材１０を支持する軸受支持部材４をアルミニウム合金等の軽合金で形成すると、軸受部材１０を含む全体の重量の軽量化を図ることができ、高速回転する主軸１２の安定性を高めることができる。
【００３３】
図２は、この発明に係る流体軸受装置の第２の実施形態を示し、要部のみを示している。この流体軸受装置は、熱伝導体１４をインナーリング１４ａとアウターリング１４ｂとで形成している点で図１に示す流体軸受装置と相違する。
【００３４】
このため、図１に示す流体軸受装置と同一の部品には同一符号を付して説明を省略する。
【００３５】
図２に示すように、熱伝導体１４をインナーリング１４ａとその外側に嵌合されたアウターリング１４ｂとで形成し、インナーリング１４ａを軸受部材１０の突出部１０ａの外周に圧入して、その下面を軸受部材１０の上面に接触させると共に、アウターリング１４ｂの下面を軸受支持部材４の突出部４ａの上面に接触させることにより、熱伝導体１４と軸受部材１０の接触面積の拡大を図ることができ、軸受部材１０から軸受支持部材４への熱伝導を高め、動圧軸受部の温度上昇をより効果的に抑制することができる。
【００３６】
【発明の効果】
以上のように、この発明においては、軸受部材の突出部と軸受支持部材との間に熱伝導体を設けて伝熱特性を高めたことにより、動圧軸受部の冷却効果を高めることができ、潤滑油の温度上昇による粘性の低下を防止し、負荷容量の低下を抑制することができる。
【図面の簡単な説明】
【図１】この発明に係る流体軸受装置の第１の実施形態を示す縦断正面図
【図２】この発明に係る流体軸受装置の第２の実施形態を示す縦断正面図
【図３】従来の流体軸受装置を示す縦断正面図
【図４】従来の流体軸受装置の他の例を示す縦断正面図
【符号の説明】
１ハウジング
３油室
４軸受支持部材
７ボール
８ダンパ隙間
９嵌合孔
１０軸受部材
１０ａ突出部
１２主軸
１３動圧軸受
１４熱伝導体
１４ａインナーリング
１４ｂアウターリング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic bearing device that rotatably supports a main shaft that is rotated at a high speed in a vertical high-speed rotating machine such as a turbo molecular pump or a flywheel.
[0002]
[Prior art]
As this type of hydrodynamic bearing device, one described in Japanese Utility Model Laid-Open No. 63-99025 has been known. In this hydrodynamic bearing device, as shown in FIG. 3 , a bearing member 22 is immersed in lubricating oil in an oil chamber 21 formed in a housing 20, and a lower surface outer peripheral portion of the bearing member 22 is supported by a plurality of balls 23. Thus, a minute damper gap 25 is formed between the upper surface of the protrusion 24 provided at the center of the bottom surface of the bearing member 22 and the center of the bottom surface of the oil chamber 21, and is disposed on the center of the top surface of the bearing member 22. A shaft end of the main shaft 26 is rotatably supported by a dynamic pressure bearing 27.
[0003]
Here, the dynamic pressure bearing 27 is formed with a concave hemispherical bearing surface 27a on the upper surface of the bearing member 22, while a hemispherical surface 27b is provided at the shaft end of the main shaft 26, and the hemispherical surface 27b and the bearing surface are provided. A spiral dynamic pressure generating groove 27c is provided in at least one of the 27a.
[0004]
In the hydrodynamic bearing device, when the main shaft 26 rotates at a high speed, the pressure of the lubricating oil between the bearing surface 27a and the hemispherical surface 27b is increased by the pumping action of the dynamic pressure generating groove 27c, and the main shaft 26 is supported by the pressure of the lubricating oil. Like to do. For this reason, the main shaft 26 rotates in a non-contact state with respect to the bearing member 22, and the main shaft 26 can be rotated at a very high speed.
[0005]
Further, the bearing member 22 is prevented from vibrating as the main shaft 26 rotates at a high speed due to a damping effect caused by the shearing resistance of the lubricating oil in the damper gap 25 formed between the lower surface of the bearing member 22 and the upper surface of the protruding portion 24. Therefore, the main shaft 26 can be stably rotated at a high speed.
[0006]
By the way, in the hydrodynamic bearing device, the dynamic pressure bearing portion generates heat due to the high speed rotation of the main shaft 26 and the temperature rises. At this time, if the cooling of the dynamic pressure bearing portion due to heat radiation is insufficient, the temperature of the dynamic pressure bearing portion increases and the viscosity of the lubricating oil in the dynamic pressure bearing portion decreases, and the load capacity of the dynamic pressure bearing portion decreases. .
[0007]
In order to eliminate such inconvenience, in the hydrodynamic bearing device described in the above publication, the size of the damper gap 25 formed between the lower surface of the bearing member 22 and the upper surface of the protruding portion 24 is in the range of 30 μm to 200 μm. The heat of the dynamic pressure bearing portion is thermally conducted from the bearing member 22 to the bottom surface of the housing 20 through the lubricating oil that fills the damper gap 25 to dissipate the heat, thereby suppressing the temperature rise of the dynamic pressure bearing portion. Yes.
[0008]
However, since the damper gap 25 is provided between the center of the lower surface of the bearing member 22 and the upper surface of the protrusion 24 provided on the bottom surface of the oil chamber 21, the damper gap 25 having a large area cannot be secured. The heat conduction from the bearing member 22 to the protruding portion 24 is insufficient, and the dynamic pressure bearing portion cannot be cooled effectively.
[0009]
In addition, since the area of the damper gap 25 is small, a sufficient damping effect for suppressing vibration of the bearing member 22 cannot be obtained.
[0010]
In order to eliminate such inconvenience, a hydrodynamic bearing device shown in FIG. 4 has been proposed. In this hydrodynamic bearing device, a disk-like bearing support member 32 is immersed in the lubricating oil accommodated in the oil chamber 31 of the housing 30, and the fitting hole 33 provided on the upper surface of the bearing support member 32 is immersed. The bearing member 34 is fitted, the outer periphery is fixed by tightening the screw 35, the main shaft 36 is disposed on the protrusion 34a provided at the center of the upper surface of the bearing member 34, and the shaft end is moved. A pressure bearing 37 is rotatably supported.
[0011]
In addition, a plate 38 on the ring is provided at the center of the lower surface of the bearing support member 32, and the plate 38 is supported by a plurality of balls 39, and the lower surface outer peripheral portion of the bearing support member 32 and the upper surface of the bottom member 40 of the oil chamber 31. A damper gap 41 is provided between them.
[0012]
In the fluid dynamic bearing device, since the damper gap 41 is provided between the outer peripheral portion of the lower surface of the bearing support member 32 and the upper surface of the bottom member 40, the damper gap 41 having a wide area can be secured. For this reason, the heat transmitted from the bearing member 34 to the bearing support member 32 can be satisfactorily conducted to the bottom member 40, and since the area of the damper gap 41 is large, the damping effect is excellent, and the vibration of the bearing member 34 is suppressed. It can suppress more effectively.
[0013]
[Problems to be solved by the invention]
Meanwhile, although the hydrodynamic bearing device shown in FIG. 4 has excellent heat dissipation characteristics from the bearing support member 32 through the damper gap and damping characteristics for suppressing vibration of the bearing member 34, the outer periphery of the bearing member 34 has a fitting hole 33. Between the projecting portion 34a which is not in contact with the inner circumference of the bearing support member 32 and whose bottom surface is only in contact with the bottom surface of the fitting hole 33 of the bearing support member 32 and is likely to generate heat due to the high-speed rotation of the main shaft 36. Since the heat transfer path is long and the hydrodynamic bearing portion is projected, the cross-sectional area of the heat transfer path is small. Therefore, the cooling effect of the protrusion 34a due to heat conduction is poor, and the temperature rise of the dynamic pressure bearing 37 cannot be effectively suppressed.
[0014]
As a result, the viscosity of the lubricating oil in the hydrodynamic bearing portion decreases due to a temperature increase due to high-speed rotation of the main shaft, and the load capacity decreases due to the decrease in viscosity.
[0015]
This invention makes it a subject to improve the heat-transfer characteristic between a bearing member and a bearing support member, to improve the cooling effect of a hydrodynamic bearing part, and to prevent the load capacity of a fluid dynamic bearing device from being reduced.
[0016]
[Means for Solving the Problems]
In order to solve the above problems, in the first invention, a housing having an oil chamber, a bearing support member immersed in the hydraulic oil in the oil chamber, a lower surface of the bearing support member, and a bottom surface of the oil chamber A plurality of balls that support the bearing support member so that a minute damper gap is formed therebetween, and a bearing member that is fitted in a fitting hole formed in a center portion of the upper surface of the bearing support member, In the hydrodynamic bearing device in which a protrusion is provided at the center of the upper surface of the bearing member and the shaft end of the main shaft provided on the protrusion is rotatably supported by a dynamic pressure bearing, on the outer periphery of the fitting hole of the bearing support member , the high have protrusions than the outer peripheral portion of the fitted bearing member into the fitting hole is provided, the thermal conductivity of the high thermal conductor to conduct heat of the protruding portion of the bearing member to the bearing support member, said bearing between the projection of the outer periphery and the bearing support member of the protruding portion of the member It has adopted the only configuration.
[0017]
As described above, the bearing fitting hole periphery of the support member, the provided high have protrusions than the outer peripheral portion of the fitted bearing member into the fitting hole, heat the bearing support member projecting portion of the bearing member By providing a heat conductor having a high thermal conductivity to be conducted between the outer periphery of the protrusion of the bearing member and the protrusion of the bearing support member, between the protrusion of the bearing member and the bearing support member Heat transfer characteristics can be enhanced, and the protrusion of the bearing member can be effectively cooled by heat conduction to the bearing support member.
[0018]
For this reason, it is possible to prevent a decrease in the viscosity of the lubricating oil in the dynamic pressure bearing portion and to suppress a reduction in load capacity.
[0019]
Here, the thermal conductor is preferably formed of a metal having high thermal conductivity such as copper or aluminum. When attaching the heat conductor, a method is adopted in which the heat conductor is formed in a ring shape, the ring-shaped heat conductor is press-fitted into the outer periphery of the protrusion of the bearing member, and the lower surface is brought into contact with the upper surface of the protrusion of the bearing support member. Can be adopted.
[0020]
The ring-shaped heat conductor is formed by an inner ring and an outer ring fitted to the outside thereof, and the inner ring is press-fitted into the outer periphery of the protruding portion of the bearing member to bring the lower surface into contact with the outer peripheral portion of the bearing member, By bringing the outer ring into contact with the upper surface of the protrusion of the bearing support member, the contact area between the bearing member and the heat conductor can be increased, and the heat of the bearing member can be effectively transferred to the heat conductor. It is possible to further enhance the cooling effect of the bearing member due to heat conduction.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
It will be described below with reference to the embodiment of the present invention in FIG. 1 to FIG. As shown in FIG. 1, lubricating oil is contained in an oil chamber 3 formed on the bottom 2 of the housing 1.
[0022]
A disk-shaped bearing support member 4 is immersed in the lubricating oil in the oil chamber 3. The bearing support member 4 is made of a light alloy such as an aluminum alloy.
[0023]
A recess 5 is formed in the bottom surface of the oil chamber 3, and ring-shaped plates 6a and 6b made of a metal having excellent wear resistance such as special steel are opposed to the bottom surface of the recess 5 and the lower surface of the bearing support member 4. The bearing support member 4 is supported by a plurality of balls 7 provided between the plates 6 a and 6 b, and a small damper gap 8 is provided between the lower surface of the bearing support member 4 and the bottom surface of the oil chamber 3. It has been.
[0024]
A fitting hole 9 is formed at the center of the upper surface of the bearing support member 4, and a bearing member 10 is fitted into the fitting hole 9, and the outer peripheral portion is fixed to the bearing support member 4 by tightening screws 11. . The fitting hole periphery of the bearing support member 4, the high have protrusions 4a are provided from the outer peripheral portion of the bearing member 10 is fitted into the fitting hole 9.
[0025]
The bearing member 10 is made of a copper alloy. The bearing member 10 has a protruding portion 10 a at the center of the upper surface, and a main shaft 12 provided on the protruding portion 10 a is rotatably supported by a dynamic pressure bearing 13. The hydrodynamic bearing 13 has a concave hemispherical bearing surface 13a formed on the upper surface of the projecting portion 10a, while a hemispherical surface 13b is provided at the shaft end of the main shaft 12, and the hemispherical surface 13b includes a spiral groove. A pressure generating groove 13c is formed.
[0026]
The dynamic pressure generating groove 13c may be formed only on the bearing surface 13a, or may be formed on both the bearing surface 13a and the hemispherical surface 13b.
[0027]
Between the protrusion 10 a of the bearing member 10 and the bearing support member 4, a heat conductor 14 that conducts the heat of the protrusion 10 a to the bearing support member 4 is provided.
[0028]
The heat conductor 14 is made of a metal having high thermal conductivity such as copper or aluminum. The heat conductor 14 has a ring shape, is press-fitted into the outer periphery of the protruding portion 10 a, and the outer peripheral portion of the lower surface is in contact with the upper surface of the bearing support member 4.
[0029]
As described above, the lower surface outer peripheral portion of the heat conductor 14 press-fitted into the outer periphery of the protruding portion 10 a of the bearing member 10 is brought into contact with the upper surface of the protruding portion 4 a of the bearing support member 4, so When the bearing portion generates heat and the temperature of the protruding portion 10a rises, the heat is well conducted from the heat conductor 14 to the bearing support member 4. The protrusion 10a is cooled by heat dissipation due to the heat conduction.
[0030]
For this reason, the fall of the viscosity by the temperature rise of the lubricating oil between the bearing surface 13a and hemispherical surface 13b of a dynamic pressure bearing part can be prevented, and the reduction of the load capacity of a dynamic pressure bearing part can be suppressed.
[0031]
Here, as shown in the embodiment, when the bearing member 10 is formed of a copper alloy, the slidability during contact rotation of the main shaft 12 can be improved, and when the foreign matter enters the dynamic pressure bearing portion, the foreign matter Is buried in the bearing surface 13a and can suppress a decrease in rotational characteristics due to the biting of foreign matter.
[0032]
Further, if the bearing support member 4 that supports the copper alloy bearing member 10 is made of a light alloy such as an aluminum alloy, the overall weight including the bearing member 10 can be reduced, and the spindle 12 that rotates at high speed can be stabilized. Can increase the sex.
[0033]
FIG. 2 shows a second embodiment of the hydrodynamic bearing device according to the present invention, and shows only the main part. This hydrodynamic bearing device is different from the hydrodynamic bearing device shown in FIG. 1 in that the heat conductor 14 is formed by an inner ring 14a and an outer ring 14b.
[0034]
For this reason, the same parts as those of the hydrodynamic bearing device shown in FIG.
[0035]
As shown in FIG. 2, the heat conductor 14 is formed of an inner ring 14a and an outer ring 14b fitted on the outer side, and the inner ring 14a is press-fitted into the outer periphery of the protruding portion 10a of the bearing member 10, The contact area between the heat conductor 14 and the bearing member 10 is increased by bringing the lower surface into contact with the upper surface of the bearing member 10 and bringing the lower surface of the outer ring 14b into contact with the upper surface of the protruding portion 4a of the bearing support member 4. Thus, heat conduction from the bearing member 10 to the bearing support member 4 can be enhanced, and the temperature rise of the hydrodynamic bearing portion can be more effectively suppressed.
[0036]
【The invention's effect】
As described above, in the present invention, the cooling effect of the hydrodynamic bearing portion can be enhanced by providing a heat conductor between the protruding portion of the bearing member and the bearing support member to enhance the heat transfer characteristics. Further, it is possible to prevent a decrease in viscosity due to an increase in the temperature of the lubricating oil and to suppress a decrease in load capacity.
[Brief description of the drawings]
[1] The longitudinal sectional front view showing a second embodiment of the fluid bearing apparatus according to a first longitudinal front view showing an embodiment of FIG. 2 the invention of the fluid bearing device according to the invention [3] Conventional Longitudinal front view showing a hydrodynamic bearing device [FIG. 4] Longitudinal front view showing another example of a conventional hydrodynamic bearing device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 3 Oil chamber 4 Bearing support member 7 Ball 8 Damper clearance 9 Fitting hole 10 Bearing member 10a protrusion part 12 Main shaft 13 Dynamic pressure bearing 14 Thermal conductor 14a Inner ring 14b Outer ring

Claims

A housing having an oil chamber, a bearing support member immersed in the hydraulic fluid of the oil chamber, and a bearing support member that supports a minute damper gap between the lower surface of the bearing support member and the bottom surface of the oil chamber. A plurality of balls, and a bearing member fitted in a fitting hole formed in the center of the upper surface of the bearing support member, and a protrusion is provided in the center of the upper surface of the bearing member. In the hydrodynamic bearing device in which the shaft end of the main shaft provided on the bearing is rotatably supported by a dynamic pressure bearing, the outer periphery of the bearing member fitted in the fitting hole is arranged on the outer periphery of the fitting hole of the bearing supporting member. A heat conductor having a high thermal conductivity that provides a high protrusion and conducts heat of the protrusion of the bearing member to the bearing support member is provided between the outer periphery of the protrusion of the bearing member and the protrusion of the bearing support member. to provided, the heat conductor consists of a ring, the heat conductor Fluid bearing apparatus characterized by the outer peripheral portion of the lower surface is press-fitted to the outer periphery of the protruding portion of the bearing member is brought into contact with the upper surface of the projecting portion of the bearing support member.

The heat conductor includes an inner ring and an outer ring fitted to the outer periphery of the inner ring. The inner ring is press-fitted into the outer periphery of the protruding portion of the bearing member, and the lower surface contacts the upper surface of the bearing member. The hydrodynamic bearing device according to claim 1, wherein the lower surface of the outer ring is brought into contact with the upper surface of the protruding portion of the bearing support member .