Ntn Corporation

Yasuhiro Yamamoto

Natsuhiko Mori

Tetsuya Kurimura

Isao Komori

Kazuo Okamura

Kenji Hibi

Tatsuo Kawase

Makoto Shiranami

Shinji Komatsubara

Tetsuya Yamamoto

Kenji Ito

Yoshinori Ito

Fuminori Satoji

Masaharu Hori

Mitsuo Sasabe

Masakazu Hirata

Yasuyuki Watanabe

Hiroshi Niwa

Jun Hirade

Kimihiko Bito

Tatsuya Hayashi

Noriyuki Tsushima

Kiyotaka Kusunoki

Takashi Minami

Toshiaki Niwa

Toshihiko Tanaka

A ratio W/Wof a circumferential width Wof each of inclined hill portions Gof a radial dynamic pressure generating portion G and a circumferential width Wof each of inclined groove portions Gis 1.2 or larger. And when an inner diameter of a bearing member is D, the circumferential width Wof each of the inclined groove portions satisfies 0.2D&#x2264;W&#x2264;0.4D.

Fluid dynamic bearing device, and bearing member and shaft member for use in same

Provided is a fluid dynamic bearing device () including a rotary body (A), a bearing member () (sleeve portion) made of a sintered metal arranged on the rotary body (A), having end surfaces (), a thrust bearing gap formed by a lower end surface () of the bearing member (), filled with lubricating oil (), and a thrust dynamic pressure generating portion (B). A dynamic pressure generating action is caused in the lubricating oil in the thrust bearing gap along with rotation of the rotary body (A) to support the rotary body (A) in one thrust direction in a non-contact manner. The bearing member () has an oil permeability of 4% or more with respect to a mass flow rate of the lubricating oil () flowing along the thrust dynamic pressure generating portion (B) during the rotation of the rotary body (A).

Fluid dynamic bearing device and motor provided with same

A fluid dynamic bearing device including: a bearing sleeve fixed to an inner periphery of a housing; a shaft member removably inserted along an inner periphery of the bearing sleeve; an annular member having an inner peripheral surface for defining a radial gap together with an outer peripheral surface of the shaft member; and radial bearing portions and a thrust bearing portion for supporting the shaft member. At least the radial bearing gap at each of the radial bearing portions, and a bottom gap having the thrust bearing portion received therein are filled with lubricating oil. A void section is formed in an interior space of the housing. Assuming that drepresents a gap width of the radial bearing gap and drepresents a gap width of the radial gap, a relationship of 30d&#x2266;d&#x2266;250dis satisfied.

Fluid dynamic bearing device and motor with same

Providing a fluid dynamic bearing device, wherein the outer member comprises a member formed by a pressing process on a plate member, the radial bearing surface and at least the one of the thrust bearing surfaces of the outer member being formed by the pressing process, and wherein at least a part of the inner member, which forms the radial bearing surface and the thrust bearing surfaces of the inner member, is made of a sintered metal.

Fluid dynamic bearing device and assembly method for same

A fluid dynamic bearing device which can exhibit high bearing performance is provided at low costs by forming a highly accurate bearing gap. At least a region in the outer circumferential surface of a shaft which faces the radial bearing gap is constituted of an electroformed part, and the region of the shaft excluding the electroformed part is constituted of a resin portion.

Fluid dynamic bearing device

Fine particles () are retained by an electroformed portion () in a dispersed state, and the fine particles () exposed from an outer peripheral surface () of the electroformed portion () are molten so as to form micro projections () integrated with a resin portion (). The micro projections () enters into fine-particle traces () formed in the electroformed portion () to exert an anchor effect, to thereby increase a fixation force between the resin portion () and the electroformed portion ().

Electroformed bearing and method of manufacturing same

An inner periphery of a molded part having a step from an inner periphery of an electroformed part is molded to a nonconductive coating which covers the surface of a master. When the nonconductive coating is removed, a radial clearance having a diameter greater than that of a bearing clearance is created between the inner periphery of the molded part, which is exposed to the interior, and an outer periphery of a shaft member. A bearing member which forms the bearing and radial clearance with the shaft member is manufactured by performing electroforming on the master with the nonconductive coating formed on part of the surface of the master, thereby forming the electroformed part; then injection molding the bearing member with the electroformed part and the nonconductive coating on the surface of the master inserted into a cavity; and then removing the nonconductive coating from the bearing member.

Bearing member and method for manufacturing the same, and bearing unit having bearing member and method for manufacturing the same

A shaft member for a fluid dynamic bearing device that has a recess to cause a dynamic pressure effect of a fluid in a bearing clearance, which is formed on it by rolling, and where a surface layer portion of the recess and a surface layer portion of a surrounding region of the recess has a nitride layer, and where nitrogen is diffused and penetrated in a material of the shaft member that is formed by nitriding after the rolling.

Shaft member for fluid dynamic bearing device

Provided is a shaft member for a fluid dynamic bearing device, which is excellent in wear resistance and which can exert a high dynamic pressure effect. A shaft material () is rolled to form a recess () for causing a dynamic pressure effect of a lubricating oil in a radial bearing clearance (). In this case, in a surface layer portion () of the recess () to be formed in an outer peripheral surface () of the shaft material (), a first hardened layer () is formed by rolling. At the same time, also in a surface layer portion () of a surrounding region () of the recess (), a first hardened layer () is formed by rolling at a partial region thereof. After the recess () is formed by the rolling, barreling is applied to the shaft material (). As a result, an outermost surface layer portion of the surface layer portion () is formed with a second hardened layer () by the barreling. A hardness of the second hardened layer () formed in the surrounding region () is higher by 50 Hv or more and 200 Hv or less than that of the first hardened layer () formed in the recess ().

An inner space of a housing sealed with a seal member as well as internal pores of a bearing member (pores in a porous structure) are filled with a lubricating oil without the presence of air, so that the oil surface of the lubricating oil is within a seal space. Under a reduced pressure of 100 Torr, no lubricating oil leaks outside of the housing even at any attitude of the fluid lubricated bearing device such as normal, inverted, or horizontal attitude.

Fluid lubricated bearing device

The porous oil-impregnated bearingcomprises a bearing bodymade of a porous material, and oil retained in the pores of the bearing bodyby impregnation with lubricating oil or lubricating grease. The inner peripheral surface of the bearing bodyis formed with a bearing surfaceopposed to an outer peripheral surface of a shaft to be supported, with a bearing clearance defined therebetween. The bearing surfacehas a first region min which a plurality of hydrodynamic pressure generating groovesinclined in one direction with respect to the axial direction are circumferentially disposed, a second region mwhich is axially spaced from said first region mand in which a plurality of hydrodynamic pressure generating groovesinclined in the other direction with respect to the axial direction are circumferentially disposed, and an annular smooth region n disposed between the first and second regions mand m

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Kuwana, Japan

Yasuhiro Yamamoto