Abstract: An internal pore of a sintered metal bearing 8 is impregnated with a lubricating fluid, and a radial dynamic pressure generation portion 8a1 is formed on an inner peripheral surface 8a. An axial dimension L is 4.8 nm or less, a thickness dimension t is 0.5 mm or more and 1.5 nm or less, and a ratio L/D2 of the axial dimension L to an outer diameter dimension D2 is 0.24 or more and 0.6 or less.

Abstract: A fluid dynamic bearing device 1 includes: a shaft member 2; a bearing sleeve 8 that has the shaft member 2 inserted into the inner periphery thereof; a housing 7 that holds the bearing sleeve 8 on the inner periphery thereof and has a bottomed cylindrical shape having an opening at an end portion on one axial side; and a seal member 9 provided at the opening of the housing 7. The seal member 9 has a disk portion 9a disposed on one axial side of the bearing sleeve 8, and a protrusion (cylindrical portion 9b) protruding to the other axial side from an outer diameter end of the disk portion 9a. An outer peripheral surface 9c of the seal member 9 is fixed to an inner peripheral surface 7a1 of the housing 7.

Abstract: Provided is a slide bearing (bearing sleeve (8)), comprising an oxidized green compact in which particles (11) of metal powder are bonded to each other by an oxide film (12) formed on surfaces of the particles (11). The oxidized green compact has a bearing surface (A, B) configured to slide, through intermediation of a lubricating film, relative to a mating member (shaft member (2)) to be supported. The bearing surface (A, B) has a large number of opening portions (13a), and the large number of opening portions (13a) and inner pores (13b) are interrupted in communication therebetween by the oxide film (12).

Abstract: Provided is a slide bearing (bearing sleeve (8)), comprising an oxidized green compact in which particles (11) of metal powder are bonded to each other by an oxide film (12) formed on surfaces of the particles (11). The oxidized green compact has a bearing surface (A, B) configured to slide, through intermediation of a lubricating film, relative to a mating member (shaft member (2)) to be supported. The bearing surface (A, B) has a large number of opening portions (13a), and the large number of opening portions (13a) and inner pores (13b) are interrupted in communication therebetween by the oxide film (12).

Abstract: A fluid dynamic bearing device 1 includes: a shaft member 2; a bearing sleeve 8 that has the shaft member 2 inserted into the inner periphery thereof; a housing 7 that holds the bearing sleeve 8 on the inner periphery thereof and has a bottomed cylindrical shape having an opening at an end portion on one axial side; and a seal member 9 provided at the opening of the housing 7. The seal member 9 has a disk portion 9a disposed on one axial side of the bearing sleeve 8, and a protrusion (cylindrical portion 9b) protruding to the other axial side from an outer diameter end of the disk portion 9a. An outer peripheral surface 9c of the seal member 9 is fixed to an inner peripheral surface 7a1 of the housing 7.

Abstract: A fluid dynamic bearing 8 includes a green compact 10 of a raw material powder M including as a main component a metal powder capable of forming an oxide film 12, and dynamic pressure generating portions A1 and A2 provided in a region 8a where a bearing gap is formed between a surface of the green compact 10 and a supported portion 2a1, and the oxide film 12 formed between particles 11 of the metal powder, and the fluid dynamic bearing 8 exhibits a radial crushing strength of 150 MPa or more. Here, the metal powder is used which exhibits a particle size distribution in which a ratio of the metal powder of 100 ?m or more to the metal powder as a whole is 30 wt % or more, and a cumulative 50% diameter is 50 ?m or more and 100 ?m or less.

Abstract: A charging amount of lubricating oil (11) into an internal space of a housing (7) is adjusted so that, within a range of a use temperature, an oil level of the lubricating oil (11) is positioned on a lower side with respect to an upper end portion of a chamfered portion (8f) formed in an upper-end inner peripheral edge portion of a bearing member (8). The bearing member (8) integrally includes: a small-diameter cylindrical portion (81); and a large-diameter cylindrical portion (82). Under a state in which an upper end surface (8c) of the small-diameter cylindrical portion (81) is exposed to an atmosphere, the large-diameter cylindrical portion (82) is sandwiched from both sides in the axial direction with an annular member (9) and a bottom portion (7b) of the housing (7) so that the bearing member (8) is fixed along an inner periphery of the housing (7).

Abstract: An oil-impregnated sintered bearing (8) includes a copper-iron-based sintered compact containing 40 mass % or more of copper, and has inner pores impregnated with an oil. The sintered compact has: a copper structure derived from copper powder (13) of partially diffusion-alloyed powder (11) in which copper powder (13) having a particle diameter of 20 ?m or less is diffused on and joined to a surface of iron powder (12) in advance; and a copper structure derived from elemental copper powder (14).

Abstract: A sintered metal bearing is formed of a porous body formed through sintering of a compact obtained through compression molding of raw-material power. The sintered metal bearing includes a dynamic pressure generating portion formed on an inner peripheral surface, the dynamic pressure generating portion including dynamic pressure generating groove array regions formed continuously to each other in an axial direction of the sintered metal bearing. The dynamic pressure generating groove array regions each include a plurality of dynamic pressure generating grooves arrayed so as to be inclined with respect to a circumferential direction of the sintered metal bearing. An axial dimension of the sintered metal bearing is set to 6 mm or less, and a density ratio of the sintered metal bearing is set to 80% or more and 95% or less.

Abstract: A charging amount of lubricating oil (11) into an internal space of a housing (7) is adjusted so that, within a range of a use temperature, an oil level of the lubricating oil (11) is positioned on a lower side with respect to an upper end portion of a chamfered portion (8f) formed in an upper-end inner peripheral edge portion of a bearing member (8). The bearing member (8) integrally includes: a small-diameter cylindrical portion (81); and a large-diameter cylindrical portion (82). Under a state in which an upper end surface (8c) of the small-diameter cylindrical portion (81) is exposed to an atmosphere, the large-diameter cylindrical portion (82) is sandwiched from both sides in the axial direction with an annular member (9) and a bottom portion (7b) of the housing (7) so that the bearing member (8) is fixed along an inner periphery of the housing (7).

Abstract: Provided is a sintered bearing, which is obtained by sintering a green compact including: a partially diffusion-alloyed powder (11) in which a copper powder (13) adheres onto a surface of an iron powder (12) through partial diffusion; elemental copper powder; low-melting point metal powder having a lower melting point than copper; and graphite powder. The partially diffusion-alloyed powder (11) has a maximum particle diameter of 106 ?m or less, and the copper powder (13) of the partially diffusion-alloyed powder (11) has a maximum particle diameter of 10 ?m or less.

Abstract: An oil-impregnated sintered bearing (8) includes a copper-iron-based sintered compact containing 40 mass % or more of copper, and has inner pores impregnated with an oil. The sintered compact has: a copper structure derived from copper powder (13) of partially diffusion-alloyed powder (11) in which copper powder (13) having a particle diameter of 20 ?m or less is diffused on and joined to a surface of iron powder (12) in advance; and a copper structure derived from elemental copper powder (14).

Abstract: A ratio W1/W2 of a circumferential width W1 of each of inclined hill portions G2 of a radial dynamic pressure generating portion G and a circumferential width W2 of each of inclined groove portions G3 is 1.2 or larger. And when an inner diameter of a bearing member is D, the circumferential width W2 of each of the inclined groove portions satisfies 0.2D?W2?0.4D.

Abstract: Provided is a fluid dynamic bearing device (1) including a rotary body (2A), a bearing member (22) (sleeve portion) made of a sintered metal arranged on the rotary body (2A), having end surfaces (22b, 22c), a thrust bearing gap formed by a lower end surface (22c) of the bearing member (22), filled with lubricating oil (11), 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 (2A) to support the rotary body (2A) in one thrust direction in a non-contact manner. The bearing member (22) has an oil permeability of 4% or more with respect to a mass flow rate of the lubricating oil (11) flowing along the thrust dynamic pressure generating portion (B) during the rotation of the rotary body (2A).

Abstract: A sintered bearing includes a sintered metal formed by using a metal powder mixture containing copper powder and iron powder. The metal powder mixture contains 80 wt % or more of particles having an average particle diameter of less than 45 ?m. The copper powder contains electrolytic copper powder. The electrolytic copper powder contains 40 number % or more of particles having a circularity of 0.64 or more.

Abstract: A ratio W1/W2 of a circumferential width W1 of each of inclined hill portions G2 of a radial dynamic pressure generating portion G and a circumferential width W2 of each of inclined groove portions G3 is 1.2 or larger. And when an inner diameter of a bearing member is D, the circumferential width W2 of each of the inclined groove portions satisfies 0.2D?W2?0.4D.

Abstract: 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 d1 represents a gap width of the radial bearing gap and d2 represents a gap width of the radial gap, a relationship of 30d1?d2?250d1 is satisfied.

Abstract: A sintered metal bearing is formed of a porous body formed through sintering of a compact obtained through compression molding of raw-material power. The sintered metal bearing includes a dynamic pressure generating portion formed on an inner peripheral surface, the dynamic pressure generating portion including dynamic pressure generating groove array regions formed continuously to each other in an axial direction of the sintered metal bearing. The dynamic pressure generating groove array regions each include a plurality of dynamic pressure generating grooves arrayed so as to be inclined with respect to a circumferential direction of the sintered metal bearing. An axial dimension of the sintered metal bearing is set to 6 mm or less, and a density ratio of the sintered metal bearing is set to 80% or more and 95% or less.

Abstract: A fluid dynamic bearing device (1), including: a bearing member (22) on a rotary side; a housing (7) on a stationary side; a sealing member (9); a radial bearing gap to be formed between an outer peripheral surface (22a) of the bearing member (22) and an inner peripheral surface (7a2) of the housing (7); and a thrust bearing gap to be formed between a lower end surface (22c) of the bearing member (22) and an inner bottom surface (7b1) of the housing (7). The radial bearing gap and the thrust bearing gap are filled with lubricating oil (11). An axial gap (10) containing air is formed between an upper end surface (22b) of the bearing member (22) and a lower end surface (9b) of the sealing member (9), which faces the upper end surface (22b) of the bearing member (22).

Abstract: A sintered bearing includes a sintered metal formed by using a metal powder mixture containing copper powder and iron powder. The metal powder mixture contains 80 wt % or more of particles having an average particle diameter of less than 45 ?m. The copper powder contains electrolytic copper powder. The electrolytic copper powder contains 40 number % or more of particles having a circularity of 0.64 or more.