Abstract: A bearing stiffness of a sintered metal sleeve is prevented from lowering. A sleeve includes an inner section formed of metal powder for sintering and a resin for impregnation, and a surface deformation section which covers a surface of the inner section and is formed by shot blast process. Since the surface deformation section is formed by the shot blast process, the number of pores formed between the metal powder for sintering near the surface can be reduced. In this way, a supporting pressure at a bearing portion can be prevented from being released out through the pores, and the bearing stiffness can be prevented from lowering.

Abstract: In a hydrodynamic bearing device in which a radial bearing face having a dynamic pressure generating groove on a shaft or an inner periphery of a sleeve is provided and a clearance between the shaft and the sleeve is filled with lubricant, an annular depression is provided on one end face of the sleeve adjacent to a rotor hub and a cover plate for covering the depression is attached to the sleeve so as to define a reservoir for the lubricant or air for the purpose of preventing such a risk that absence of an oil film occurs in clearances of a bearing of the hydrodynamic bearing device due to outflow of oil upon forcing of the oil by air received into the bearing. A step portion is provided on the other end face of the sleeve such that the step portion and the reservoir are communicated with each other by a communication hole. During operation of the hydrodynamic bearing device, air in the hydrodynamic bearing device reaches the reservoir via the communication hole so as to be discharged from the reservoir.

Abstract: A sleeve 1 is fixed on a base. Radial dynamic-pressure generating grooves 1A and 1B are provided on an inner surface of the sleeve 1. A thrust plate 4 hermetically seals a lower opening end of the sleeve 1. A shaft 2 is inserted inside the sleeve 1, being allowed to revolve. A flange 3 is fixed at the bottom end of the shaft 2, and its lower surface is placed close to an upper surface of the thrust plate 4. Thrust dynamic-pressure generating grooves 3A and 3B are provided on the surfaces of the flange 3. Gaps A–H among the sleeve 1, the shaft 2, the flange 3, and the thrust plate 4 are filled with a lubricant 5. Hollows 1C–1F are provided on the inner surface of the sleeve 1. The gaps A and C over the thrust dynamic-pressure generating grooves 3A and 3B and their vicinities are narrower than the surrounding gaps B and D (A<B, A<D, C<B, and C<D), and the surrounding gaps B and D are narrower than the gap H in the upper opening end of the sleeve 1 and its vicinity (B<H and D<H).

Abstract: A fluid dynamic bearing device including a shaft having an interior pressure regulating hole by which a center portion of a thrust surface confronting a thrust plate and a lubricant pool portion of an inner circumferential surface of a sleeve are communicated with each other. Thus, the device is capable of obtaining stable thrust floating characteristics and preventing leaks of the lubricant as well as exhaustion of the lubricant.

Abstract: An object of the present invention is to provide a hydrodynamic bearing device having a high reliability which can achieve miniaturization and reduction of weight and thickness, and a motor and a disc driving apparatus using the same. In the hydrodynamic bearing device according to the present invention, a sleeve through which a shaft penetrates has a first opposing surface substantially orthogonal to a central axis of the shaft at one end and has a second opposing surface at the other end. A thrust plate having a disc shape which is fixed near one end of the shaft or which is integrally formed with the shaft is positioned so as to oppose the first opposing surface of the sleeve. A seal plate positioned near the other end of the shaft is positioned with a gap to the second opposing surface of the sleeve.

Abstract: A hydrodynamic bearing device is provided for use with a spindle motor. The hydrodynamic bearing device has a sleeve made of a sintered metal that is obtained by sintering a sintering material that is iron, an iron alloy, copper, a copper alloy or a mixture thereof. This sintered metal has independent pores, which do not communicate with each other, by selecting conditions for forming a desired sintered body within a predetermined range. The conditions includes a grain size of powdered metal of a material for the sintered metal, a molding pressure when the molded body is formed, sintering temperature and sintering period in the sintering step.

Abstract: A hydrodynamic bearing device in which an introducing minimum clearance for causing capillary phenomenon is formed from the location in the proximity of the opening of a communicating path to the open end of the bearing hole in between the cover and the end face on the open end of the sleeve so that the operating fluid from the communicating path in the sleeve flows into the bearing hole by the capillary phenomenon; a vent hole leading to the outside air is formed on the cover; a fluid storage space for storing the operating fluid is formed on the inside surface of the cover or the end face on the open end of the sleeve to communicate the introducing minimum clearance and the vent hole in the circumferential direction; and the air bubbles separated at the fluid storage space are exhausted outward from the vent hole.

Abstract: A hydrodynamic bearing device includes a sleeve having a bearing bore substantially at a center portion, a shaft inserted in the bearing bore in a rotatable manner, a thrust plate for supporting an end of the shaft in the thrust direction and an upper retaining portion that has an opening portion through which the shaft passes and covers the upper surface of the sleeve. A radial hydrodynamic bearing is formed between the bearing bore of the sleeve and the shaft, while a thrust hydrodynamic bearing is formed between the thrust plate and an end of the shaft. A first space is formed between the upper surface of the sleeve and the upper retaining portion. A second space is formed between the upper retaining portion and a step portion.

Abstract: A fluid dynamic bearing device is disclosed in which, in the materials used for the sleeve of the fluid dynamic bearing device, particles of free-cutting elements and free-cutting alloys added to iron-based free-cutting steel, ferrite-based free-cutting stainless steel, and so on are reduced in size to about 0.1 to 0.5 ?m. The result is smaller crystals of free-cutting alloy, and particularly manganese sulfide, on the inner peripheral face of the bearing hole of the sleeve made of free-cutting steel, which makes the inner peripheral face of the sleeve smoother. Also, the carbon content of free-cutting steel is kept to 0.1% or less, which lowers the hardness of the material and extends the service life of the tool used to cut the dynamic pressure generation grooves.

Abstract: A hydrodynamic bearing device capable of inhibiting leakage of a working fluid to an outside of a bearing and preventing reduction in radial bearing rigidity, and capable of keeping a gap between a thrust bearing and a radial bearing favorable and rotating stably. The hydrodynamic bearing device includes a shaft relatively rotatably inserted into a bearing hole of a sleeve, a radial bearing surface having dynamic pressure generating grooves formed on at least one of an outer peripheral surface of the shaft and an inner peripheral surface of the sleeve, and a gap filled with a working fluid between the shaft and the sleeve. The shaft is made of high manganese chrome steel or stainless steel, and the sleeve is entirely made of sintered metal of metal particles including at least 60% by weight of iron or copper. Resin, metal or water glass is impregnated in pores on a surface of the sintered metal and cured.

Abstract: A rotatable hub in which a supporting shaft having hydrodynamic pressure generating grooves is inserted comprises an annular thrust bearing plate in its lower portion and annular permanent magnets in its upper portion. The thrust bearing plate is inserted between the lower end face of the supporting shaft and a thrust flange fixed to the supporting shaft, maintaining the respective clearances D and E. The permanent magnets on the hub are confronting in such a manner that an upward and downward repulsive forces are generated between permanent magnets mounted on the supporting shaft, respectively maintaining the clearances B and C. Since the clearances B and C are greater than the clearances D and E, the permanent magnets will not mutually contact even when the hub is caused to move upward or downward by an external force during rotation and the thrust bearing plate contacts with the lower end face of the supporting shaft or the thrust flange.

Abstract: In order to suppress the increase of torque loss at low temperature and the increase of shaft swinging at high temperature and to improve the workability of the sleeve, high manganese chromium steel or austenitic stainless steel is used as the material of the shaft, sulfur free-machining steel is used as the material of the sleeve, and the surface thereof is coated with plating primarily containing nickel and phosphorus. Hence, it is possible to obtain a hydrodynamic bearing wherein the changes in the characteristics of the bearing owing to the change in the viscosity of a lubricant depending on temperature change can be prevented, in addition, the workability of the sleeve and the dynamic pressure generation grooves and the wear resistance of the bearing can be made best.

Abstract: Radial dynamic pressure grooves are provided in a first region 4A and a second region 4B on the side of a fixed shaft 2. A vent 2D is provided inside the top end 2A of the fixed shaft 2. The vent 2D connects spaces over and under a flange 3 to each other. The flange 3 in an annular shape is fixed at the top end 2A of the fixed shaft 2. Thrust dynamic pressure grooves 3A and 3B are provided on the surfaces of the flange 3. A circulation hole 3C is provided in the flange 3, and connects spaces over and under the flange 3 to each other. A sleeve 4 revolves around the fixed shaft 2. A thrust plate 6 in an annular shape is fixed at the top of the sleeve 4 and opposed to the flange 3. The first region 4A, the second region 4B, the thrust dynamic pressure grooves 3A and 3B, and the circulation hole 3C of the flange 3 are filled with a lubricant 7.

Abstract: In order to provide a high-accuracy long-life hydrodynamic bearing not causing oil film breakage in bearing clearances and a disc rotation apparatus using the bearing, when the outside diameter of the herringbone pattern of dynamic pressure generation grooves provided on at least one of the opposed faces of a flange and a thrust plate is designated as dlo, the inside diameter thereof is designated as dli and the diameter of the turn-back part thereof is designated as dlm, the diameter dlm of the turn-back part is set so as to satisfy the relationships represented by the following equations:

Abstract: A sleeve 1 is fixed on a base. Radial dynamic-pressure generating grooves 1A and 1B are provided on an inner surface of the sleeve 1. A thrust plate 4 hermetically seals a lower opening end of the sleeve 1. A shaft 2 is inserted inside the sleeve 1, being allowed to revolve. A flange 3 is fixed at the bottom end of the shaft 2, and its lower surface is placed close to an upper surface of the thrust plate 4. Thrust dynamic-pressure generating grooves 3A and 3B are provided on the surfaces of the flange 3. Gaps A-H among the sleeve 1, the shaft 2, the flange 3, and the thrust plate 4 are filled with a lubricant 5. Hollows 1C-1F are provided on the inner surface of the sleeve 1. The gaps A and C over the thrust dynamic-pressure generating grooves 3A and 3B and their vicinities are narrower than the surrounding gaps B and D (A<B, A<D, C<B, and C<D), and the surrounding gaps B and D are narrower than the gap H in the upper opening end of the sleeve 1 and its vicinity (B<H and D<H).

Abstract: A pressure regulating hole by which a center portion of a thrust surface confronting a thrust plate and a lubricant pool portion of an inner circumferential surface of a sleeve are communicated with each other is provided inside the shaft in a fluid dynamic bearing device. Thus, the device is capable of obtaining stable thrust floating characteristics and preventing leaks of the lubricant as well as exhaustion of the lubricant.

Abstract: In order to provide a high-accuracy long-life hydrodynamic bearing not causing oil film breakage in bearing clearances and a disc rotation apparatus using the bearing, when the outside diameter of the herringbone pattern of dynamic pressure generation grooves provided on at least one of the opposed faces of a flange and a thrust plate is designated as d1o, the inside diameter thereof is designated as d1i and the diameter of the turn-back part thereof is designated as d1m, the diameter d1m is selected so that the difference between the diameters dsy and d1m becomes 0.05 mm or more and 0.

Abstract: In a hydrodynamic bearing according to the present invention a fixed shaft has different diameter sizes by positions so that overflow or splashing of lubricant out of the apparatus is prevented due to a centrifugal force during high-speed rotation, and lubricant reservoirs are provided in narrower clearances and in wider clearances so that the lubricant is induced to move toward lubricant reservoirs in narrower clearances due to surface tension while the hydrodynamic bearing is in stop, therefore overflow of the lubricant is prevented at the time of starting up.

Abstract: A hydro dynamic gas bearing having a sleeve with one end closed and connected to a front end of a shaft supported at its proximal end relative to a base on a fixed side, a plurality of hydro dynamic pressure generating grooves on at least one of an outer peripheral surface of the shaft and an inner peripheral surface of the sleeve opposite the outer peripheral surface, and a through hole communicating with the outside of the base extending from the front end to the proximal end of the shaft, the through hole having an air vent for adjusting pressure between the shaft and the sleeve for adjustment of discharge air so that the sleeve rotates in a contactless fashion relative to the shaft.

Abstract: A rotatable hub in which a supporting shaft having hydrodynamic pressure generating grooves is inserted comprises an annular thrust bearing plate in its lower portion and annular permanent magnets in its upper portion. The thrust bearing plate is inserted between the lower end face of the supporting shaft and a thrust flange fixed to the supporting shaft, maintaining the respective clearances D and E.