Spindle motor and disk drive apparatus

A spindle motor comprising:

• a stationary portion including a shaft extending along a central axis extending upward and downward;
• and
• a rotating portion including a rotatable sleeve around the shaft;
• wherein
• the stationary portion further includes:
• the shaft;
• a circular plate portion that extends from the shaft to a radial direction outer side;
• a wall portion that extends upward from an outer edge of the circular plate portion and has a cylindrical or substantially cylindrical shape;
• and
• a plate portion that surrounds the shaft above the circular plate portion and has an annular or substantially annular shape;
• the plate portion includes:
• a flat plate portion that extends from an outer circumferential surface of the shaft to the radial direction outer side;
• and
• an annular convex portion that extends downward from an outer edge of the flat plate portion and has an annular or substantially annular shape;
• an upper radial dynamic pressure groove array and a lower radial dynamic pressure groove array are arranged apart from each other or adjacent to each other in an axial direction on one or both of an inner circumferential surface of the sleeve and the outer circumferential surface of the shaft;
• the sleeve includes:
• an annular portion that has an annular or substantially annular shape;
• an outer side cylindrical portion that extends upward from an outer edge of an upper surface of the annular portion;
• and
• an inner side cylindrical portion that extends upward from an inner edge of the upper surface of the annular portion;
• the annular convex portion includes a plate inclined surface configured such that a distance between the plate inclined surface and the central axis increases downwardly;
• the inner side cylindrical portion includes a sleeve inclined surface configured such that a distance between the sleeve inclined surface and the central axis decreases upwardly;
• the plate inclined surface and the sleeve inclined surface face each other via a gap;
• the inner side cylindrical portion and the upper radial dynamic pressure groove array are superimposed in a radial direction;
• the upper radial dynamic pressure groove array includes a plurality of upper spiral grooves that is inclined in one direction with respect to the axial direction and a plurality of lower spiral grooves that is inclined in another direction opposite to the one direction;
• the plurality of upper spiral grooves and the plurality of lower spiral grooves are arranged apart from each other or adjacent to each other in the axial direction;
• and
• a lower end of the plurality of upper spiral grooves is positioned farther on an upper side than the upper surface of the annular portion.