Spindle motor, and disk drive utilizing the spindle motor

A spindle motor, comprising:

• a shaft;
• a sleeve formed with a through-hole for rotary-play insertion of said shaft;
• a rotor having a round top plate in the rotational center of which said shaft is constituted integrally, and a circular cylindrical wall depending from said top plate;
• a radial bearing section configured by an oil-retaining micro-gap being formed in between an inner circumferential surface of said sleeve and an outer circumferential surface of said shaft, and by dynamic-pressure-generating grooves being provided for inducing, in response to said rotor spinning, fluid dynamic pressure in the oil retained in the micro-gap;
• a thrust bearing section configured by an oil-retaining micro-gap being formed in between an upper-end face of said sleeve and a bottom face of said top plate, and by dynamic-pressure-generating grooves being provided for inducing, in response to said rotor spinning, fluid dynamic pressure in the oil retained in the micro-gap;
• an inclined face formed on the outer circumferential surface of said sleeve, said inclined face inclined at an angle of approximately 20° to 35° with respect to the rotational center axis and sloping such that the sleeve outer diameter contracts with further separation from said rotor top plate;
• and a circular ring member affixed to the inner circumferential surface of said rotor cylindrical wall, the ring member inner circumferential surface having an inclined face inclined at an angle of approximately 15° to 30° with respect to the rotational center axis and sloping such that the ring-member inner diameter contracts with further separation from said rotor top plate and at an angle differing from that of said inclined face along said sleeve;
• wherein
• a taper-seal area inclined at an angle of approximately 2° to 15° with respect to the rotational center axis forms in between said sleeve inclined face and said ring member inclined face.