# US 7,466,050 B2 · Brushless motor and method of manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,466,050 B2 - Document ID: US7466050B2 - Status: Granted - Kind: B2 - Application number: 11/235,236 - Filed: 2005-09-27 - Published: 2006-04-27 - Granted: 2008-12-16 - Earliest claimed: 2004-10-25 - Assignees: Panasonic Corporation - Inventors: Koji Kuyama; Kumio Masuda; Kinjiro Okinaga - Web page: https://patentgrep.com/patent/US7466050B2 ## CPC - G11B 19/2018: {Incorporating means for passive damping of vibration, either in the turntable, motor or mounting} - F16C 17/026: {with helical grooves in the bearing surface to generate hydrodynamic pressure, e.g. herringbone grooves} - F16C 33/103: {retained in or near the bearing} - F16C 33/104: {in a porous body, e.g. oil impregnated sintered sleeve} - F16C 33/107: {Grooves for generating pressure} - H02K 7/08: Structural association with bearings - F16C 2370/12: Hard disk drives or the like - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract Fluid bearing mechanisms (6a and 6b) are formed between a shaft (2) and a central part (21) of an oil impregnated sintered sleeve (13). The oil impregnated sintered sleeve (13) has such an inner surface formed to be larger in aperture ratio at a thrust support end (23) and a loading end (22) than at a central part (21). With this configuration, it is possible to achieve a brushless motor which can suppress an increase in bearing loss while obtaining necessary bearing stiffness at high rpm. ## Claims ### Claim 1 A brushless motor comprising: a bracket, a shaft having a thrust support end and a loading end, the thrust support end connected to said bracket; and an oil impregnated sintered sleeve for radially supporting said shaft, said oil impregnated sintered sleeve having an inner surface larger in aperture ratio at the thrust support end and the loading end than at a central part of the oil impregnated sintered sleeve, wherein a gap between the shaft and oil impregnated sintered sleeve is for retaining a fluid, the shaft comprises a dynamic pressure generating groove on a surface facing the central part of the oil impregnated sintered sleeve, and the brushless motor further comprises a magnet connected to the shaft and a stator connected to the bracket for rotationally driving the motor. ### Claim 2 (depends on 1) The brushless motor according to claim 1, wherein the dynamic pressure generating groove extends from a surface opposite the central part of the oil impregnated sintered sleeve to the loading end of the shaft. ### Claim 3 (depends on 1) The brushless motor according to claim 1, wherein the inner surface of the oil impregnated sintered sleeve facing the shaft at the loading end is smaller in aperture ratio than the inner surface facing the shaft at the thrust support end of the shaft. ### Claim 4 (depends on 1) The brushless motor according to claim 1, wherein the dynamic pressure generating groove extends from a surface opposite the central part of the oil impregnated sintered sleeve to the loading end of the shaft, and a gap is formed between an outer surface of the oil impregnated sintered sleeve and an inner surface of the bearing housing. ### Claim 5 (depends on 1) The brushless motor according to claim 1, wherein the inner surface facing the shaft near the end face of the loading end of the oil impregnated sintered sleeve is smaller in aperture ratio than the inner surface facing the shaft near the opposite end face, and a gap is formed between an outer surface of the oil impregnated sintered sleeve and an inner surface of the bearing housing, the gap opposing a position where the bearing housing is held in the holding portion of the bracket. ### Claim 6 (depends on 1) A brushless motor according to claim 1, further comprising a rough part and a dense part in a surface of said oil impregnated sintered sleeve, wherein said rough and dense parts are formed in said oil impregnated sintered sleeve after the oil impregnated sintered sleeve is press fit and fixed into a bearing housing. ### Claim 7 A brushless motor, comprising: a shaft having a thrust support end, a loading end, and at least one dynamic pressure generating groove in a surface of the shaft; an oil impregnated sintered sleeve for supporting the shaft in a radial direction, said oil impregnated sintered sleeve having rough parts with a large aperture ratio on an inner surface at the loading end of the shaft and the thrust support end of the shaft, and having a dense part with a small aperture ratio on an inner surface between the rough parts, said dense part facing said dynamic pressure generating groove of the shaft; a cylindrical bearing housing for supporting the oil impregnated sintered sleeve in a radial direction; a turntable mounted to said loading end of the shaft for holding a disk; a frame fixed to said shaft; a cylindrical rotor magnet fixed to an inner surface of the frame; a bracket having a holding portion for holding said cylindrical bearing housing; and a stator facing the rotor magnet and having a conductor wound via an insulator, said stator being connected to said cylindrical bearing housing and fixed with respect to said bracket. ### Claim 8 (depends on 7) The brushless motor according to claim 7, further comprising a gap between an outer surface of the oil impregnated sintered sleeve and an inner surface of the bearing housing. ### Claim 9 An dynamic pressure oil bearing in which support is provided in a radial direction, via an oil impregnated sintered sleeve, from a vicinity of a thrust support end of a shaft to a vicinity of a loading end of the shaft where a driven target is attached, a motor is rotationally driven by electromagnetic attraction and repulsion between a stator and a magnet of a rotor connected to the shaft, arid a fluid bearing mechanism is formed between the shaft and the oil impregnated sintered sleeve, wherein the fluid bearing mechanism is formed between the oil impregnated sintered sleeve and the shaft at central part in axial direction, and the oil impregnated sintered sleeve has an inner surface formed to be larger in aperture ratio at the thrust support end and the loading end than at the central part of the oil impregnated sintered sleeve. ### Claim 10 (depends on 9) The dynamic pressure oil bearing according to claim 9, wherein the fluid bearing mechanism has a dynamic pressure generating groove formed on a surface of the shaft, the surface facing the central part of the oil impregnated sintered sleeve.