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).

A bearing assembly includes a case, a bearing spring positioned inside the case, a first seal positioned between the case and the bearing spring, and a second seal. The a second seal is positioned between the case and the bearing spring and is spaced apart from the first seal, wherein the second seal is an adjustable seal that is movable between a closed position and an opened position to inhibit or allow, respectively, a fluid to flow from a cavity that is defined by the case, the bearing spring, the first seal and the second seal.

A sintered bearing exhibits less of a hard iron alloy phase, and has an excellent wear resistance and cost performance under low-revolution and high-load use conditions; and a method for producing such a sintered bearing. The sintered bearing contains Cu: 10 to 55% by mass, Sn: 0.5 to 7% by mass, Zn: 0 to 4% by mass, P: 0 to 0.6% by mass, C: 0.5 to 4.5% by mass and a remainder composed of Fe and inevitable impurities. An area ratio of a free graphite dispersed in a metal matrix of the bearing is 5 to 35%; a porosity thereof is 16 to 25%; a hardness of an iron alloy phase in the matrix is Hv 65 to 200; and raw material powders employ at least one of a crystalline graphite powder and a flake graphite powder each having an average particle size of 10 to 100 m.

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.

A double bearing comprising an inner bearing and an outer bearing, which has a greater oil content than the inner bearing, is used as a bearing for a brushless motor. The inner bearing has an upper bearing part, a lower bearing part, and a central relief part. Gaps are provided between the bearing parts and a bearing housing, along the entire axial length of all of the bearing parts of the inner bearing.

A washer member 22a and a seal member 41a are disposed in a mutually non-contacting state in the axial direction. A rotary shaft 11 has an annular groove 11a in the outer circumferential face. A minimum diameter part 11a3 of the annular groove 11a is disposed between the uppermost surface of the washer member 22a and the lowermost surface of the seal member 41a. The upper end of the annular groove 11a is disposed axially below the uppermost surface of the seal member 41a. The outer surface of the seal member 41a and the outer circumferential face of the rotary shaft 11 that faces the seal member 41a in the radial direction are subjected to oil-repellent treatment.

A bearing assembly includes a case, a bearing spring positioned inside the case, a first seal positioned between the case and the bearing spring, and a second seal. The a second seal is positioned between the case and the bearing spring and is spaced apart from the first seal, wherein the second seal is an adjustable seal that is movable between a closed position and an opened position to inhibit or allow, respectively, a fluid to flow from a cavity that is defined by the case, the bearing spring, the first seal and the second seal.

A non-contact bearing is provided. In a suspended state, the non-contact bearing is disposed with a predetermined spacing to a first guide surface. The non-contact bearing includes: a bearing body and a micro electro mechanical layer. The bearing body includes a second guide surface, wherein the second guide surface is opposite to the first guide surface. The micro electro mechanical layer is disposed on the second guide surface, and includes at least one micro sensor and/or at least one micro actuator.

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).

Provided is a sintered bearing (1) obtained by molding raw material powders containing graphite powder and metal powder in a mold, followed by sintering, in which: the graphite powder to be used includes granulated graphite powder; and a ratio of free graphite in a bearing surface (1a) of the sintered bearing is set to from 25% to 80% in terms of an area ratio. An average grain size of the granulated graphite powder is set to from 60 m to 500 m. A blending ratio of the granulated graphite powder in the raw material powders is set to from 3 wt % to 15 wt %.