Abstract: Channels and gaps inside a bearing mechanism are filled with lubricating oil, and the lubricating oil is retained in a first tapered seal portion arranged radially outward of a sleeve, and a second tapered seal portion arranged between the shaft and an upper cap placed above the sleeve. An arrangement of groove-shaped recessed portions on an inner circumferential surface of the upper cap and raised portions on a lower surface of a top portion thereof contributes to increasing a channel cross-sectional area of a channel provided between the upper cap and the sleeve to connect the first tapered seal portion with the second tapered seal portion.

Abstract: A fluid dynamic bearing device includes a sleeve having a bearing hole into which a shaft is inserted, the sleeve rotatably supporting the shaft to make relative rotation about a center axis and a bearing housing made of a cold-rolled steel plate or a galvanized steel plate, the sleeve being received within the bearing housing. The bearing housing is filled with lubricating oil mainly composed of ester. A radial dynamic pressure bearing portion is provided between an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve, the radial dynamic pressure bearing portion having radial dynamic pressure grooves for holding the lubricating oil as working fluid and for inducing a fluid dynamic pressure in the lubricating oil during the relative rotation. At least a surface region of the bearing housing remaining in contact with the lubricating oil is coated with a layer mainly composed of nickel.

Abstract: Channels and gaps inside a bearing mechanism are filled with lubricating oil, and the lubricating oil is retained in a first tapered seal portion arranged radially outward of a sleeve, and a second tapered seal portion arranged between the shaft and an upper cap placed above the sleeve. An arrangement of groove-shaped recessed portions on an inner circumferential surface of the upper cap and raised portions on a lower surface of a top portion thereof contributes to increasing a channel cross-sectional area of a channel provided between the upper cap and the sleeve to connect the first tapered seal portion with the second tapered seal portion.

Abstract: A fluid dynamic bearing device includes a sleeve having a bearing hole into which a shaft is inserted, the sleeve rotatably supporting the shaft to make relative rotation about a center axis and a bearing housing made of a cold-rolled steel plate or a galvanized steel plate, the sleeve being received within the bearing housing. The bearing housing is filled with lubricating oil mainly composed of ester. A radial dynamic pressure bearing portion is provided between an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve, the radial dynamic pressure bearing portion having radial dynamic pressure grooves for holding the lubricating oil as working fluid and for inducing a fluid dynamic pressure in the lubricating oil during the relative rotation. At least a surface region of the bearing housing remaining in contact with the lubricating oil is coated with a layer mainly composed of nickel.

Abstract: A bearing unit comprises a cylindrical oil-impregnated bearing, in which a bearing bore to support a turning shaft is formed so as to enable the turning shaft to turn; a bearing holder, in which the oil-impregnated bearing is fixed by an inner bore; a first groove being formed in an axial direction on an inner circumferential surface of the oil-impregnated bearing; and a second groove being formed in an axial direction on at least one of an outer circumferential surface of the oil-impregnated bearing and an inner circumferential surface of the bearing holder. The second groove is formed so as to have a greater depth than that of the first groove. The second groove is also formed so as to have a larger cross section than that of the first groove.

Abstract: A bearing mechanism having a sleeve including at an inner circumferential surface thereof a first bearing surface and a relief portion including a diameter greater than that of the first bearing surface is used in a spindle motor. An axial length of the first bearing surface is between approximately 1.2 mm and 1.8 mm. By virtue of such configuration, characteristics of the spindle motor are improved and an operating life of the spindle motor is extended.

Abstract: A bearing unit comprises a cylindrical oil-impregnated bearing, in which a bearing bore to support a turning shaft is formed so as to enable the turning shaft to turn; a bearing holder, in which the oil-impregnated bearing is fixed by an inner bore; a first groove being formed in an axial direction on an inner circumferential surface of the oil-impregnated bearing; and a second groove being formed in an axial direction on at least one of an outer circumferential surface of the oil-impregnated bearing and an inner circumferential surface of the bearing holder. The second groove is formed so as to have a greater depth than that of the first groove. The second groove is also formed so as to have a larger cross section than that of the first groove.

Abstract: The disclosed invention provides a sintered oil-impregnated bearing equipped with a bearing hole having a clearance structure, in which a clearer boundary is formed between the bearing surface and the clearance surface, and a manufacturing method thereof. In a bearing hole of a radial bearing, a bearing surface and another bearing surface are formed at both ends in an axial direction, and a clearance surface is formed between both the bearing surface and the bearing surface. The bearing surfaces are formed by a sizing step for a compression-molded piece that is formed by a compression molding step. In the sizing step, diameter-reduction manufacturing is carried out for an end of the compression-molded piece to form a diameter-reduced section, and then afterward, a sizing core is inserted into the bearing hole of the compression-molded piece so as to eventually form the bearing surface.

Abstract: A bearing device includes a bearing member having a bearing surface and a shaft member having a bearing surface which is relatively rotatably supported by the bearing member in such a manner that the bearing surface of the shaft member is arranged so as to face the bearing surface of bearing member. One of the bearing member and the shaft member is formed of a porous metal sintered body having hollow holes and the hollow holes in the bearing surface of the metal sintered body is filled with a lubricating resin to seal apertures in the bearing surface of the hollow holes by the lubricating resin. Thereby the bearing surface is formed of both a resin surface of the lubricating resin and a metal surface of the metal sintered body.

Abstract: A dynamic pressure bearing device, comprising: a shaft member; a bearing member relatively rotatably supporting the shaft member; a plurality of dynamic pressure generation parts provided on a peripheral face either of the shaft member or the bearing member; and a perfect circle part formed at least on a shaft end side at a region which is axially adjacent to the dynamic pressure generation part on the peripheral face where a protruded part and a recessed part are formed, wherein the dynamic pressure generation parts are respectively formed in a circumferential direction at equal angular intervals and extended in an axial direction so as to form a protruded part which makes a dimension of a minute gap between the shaft member and the bearing member to be the smallest and a recessed part which makes the dimension of the minute gap the largest, and the dimension of the minute gap in the perfect circle part is set to be the same as that in the protruded part.

Abstract: A motor comprises a cylindrical hollow rotary shaft and a rotor member which is fitted over an outer circumference of an axial end of the rotary shaft fixed by a tight fit. A bottom portion is integrally provided to the axial end portion of the rotary shaft, to which the rotor member is fixed, to close an opening at the end portion. The bottom portion has a through hole to interconnect a space inside the rotary shaft with a space outside.

Abstract: A dynamic pressure bearing device, comprising:

Abstract: The bearing apparatus used in the motor comprises a rotary shaft, a cylindrical-shaped radial bearing, and a thrust bearing for supporting the lower end portion of the rotary shaft. The rotary shaft is composed of a pipe made of stainless steel and a resin member for closing the lower end portion of the pipe. A groove for generation of dynamic pressure is not formed in the inner peripheral surface of the radial bearing or in the inner peripheral surface of the rotary shaft either. On the upper end portion of the rotary shaft, there is mounted a fan which, due to the rotation of the rotary shaft, takes in the air into the rotary shaft and, in the peripheral surface of the rotary shaft, there are formed blow-out holes for blowing out the air taken in by the fan from the outer peripheral surface of the rotary shaft.

Abstract: A dynamic pressure bearing apparatus comprises a rotary shaft, a sintered oil retaining bearing rotatably supporting the rotary shaft, the sintered oil retaining bearing having an interior surface defining an internal surface configuration for generating dynamic pressure to thereby form a dynamic pressure bearing between the rotary shaft and the sintered oil retaining bearing. The internal surface of the sintered oil retaining bearing comprises in a peripheral direction thereof, a minimum-gap section, a large-gap section and a separation groove section. The minimum-gap section has the minimum gap between the rotary shaft and the internal surface of the sintered oil retaining bearing.

Abstract: An air dynamic pressure bearing includes a shaft element, a bearing element relatively rotatably supporting the shaft element, and dynamic pressure generation grooves for generating a dynamic pressure by air formed between opposing surfaces of the shaft element and the bearing element. The bearing element is formed from a sintered alloy, and a solid lubricant material is disposed on the opposing surface of at least one of the shaft element and the bearing element.

Abstract: The dynamic pressure bearing device is structured such that the pores of porous material as they are are disposed in the surfaces thereof forming the negative pressure cancel portions 15b and a lubricating fluid is supplied to the negative pressure generating areas thereof through the pores of the negative pressure cancel portions 15b, whereby, even if recess-shaped grooves forming the negative pressure cancel portions 15b are formed shallow in depth and wide in width, or even if such grooves themselves are not formed at all, the dynamic pressure bearing device is able to fulfill its negative pressure cancel function in a sufficient manner. This makes it possible to eliminate the need for provision of the conventional recess-shaped grooves which are formed deep and narrow, thereby eliminating the need to execute an expensive operation such as a cutting operation or the like, so that the negative pressure cancel portions 15b can be formed at a low cost by inexpensive means such as by molding or the like.

Abstract: A sintered oil-impregnated bearing 20 used in a bearing device 30 is made by molding a mixture of a composite fine particles (main material) and a solid lubricant previously added to the main material in a proportion of about one weight percent to about three weight percent, wherein the main material comprises composite fine particles composed of iron powders having surfaces coated with copper, and the solid lubricant comprises fine particles made of an inorganic compound such as molybdenum disulfide and having surfaces coated with copper, sintering the mold at a temperature in a range of 650.degree. C. to 700.degree. C. to form a sintered body 20b, and impregnating the sintered body 20b with lubricant oil. Since the sintered body 20b itself has lubricity, the sintered oil-impregnated bearing is free from abrasion or seizure even if oil is used up.

Abstract: Lubricating oil composition for use with sintered porous bearings includes a poly-.alpha.-olefin hydride or ethylene-.alpha.-olefin copolymer hydride containing base oil to which at least one additive selected from the group consisting of zinc dialkyl dithiophosphate, molybdenum dialkyl dithiocarbide, molybdenum dialkyl dithiophosphate and a sulfur-phosphorus containing extreme pressure additive is added in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the base oil.

Abstract: An object of this invention is to provide a bearing device for an electric motor in which a bearing holder holding an oil-impregnated bearing provides good area contact from the beginning and can be readily formed with high productivity.

Abstract: Bearing devices which rotatably support a shaft in a bearing having a plurality of radial projections formed on either the inside peripheral surface of the bearing or the peripheral surface of the shaft are discolsed. The bearing has an oil film formed between the projections and the mating part opposite to the projections for supporting the shaft. The projections are adapted to face the mating part with a specified area sufficient to cause a specified oil film dynamic pressure effect to occur. In one form of the invention, the projections are formed of an oil impregnated sintered metal, the part of the surface of the projections facing the mating part having been subject to a filling-up process.