Bearing apparatus, spindle motor, and disk drive apparatus

A bearing apparatus comprising:

• a stationary portion including a stationary shaft arranged along a center axis extending in a vertical direction, and a first cup portion including a circular plate portion extending radially outward from the stationary shaft;
• a rotating portion arranged to rotate about the stationary shaft;
• and
• a lubricating oil;
• wherein
• the first cup portion further includes a cylindrical portion projecting downward from an outer edge portion of the circular plate portion;
• the rotating portion includes:
• a first upper surface arranged opposite to a lower surface of the circular plate portion;
• an annular recessed portion arranged to accommodate at least a lower end portion of the cylindrical portion;
• a first inner circumferential surface arranged opposite to an outer circumferential surface of the stationary shaft;
• and
• a second inner circumferential surface arranged opposite to an outer circumferential surface of the first cup portion;
• the lubricating oil is arranged in a gap between the stationary and rotating portions;
• at least one of the outer circumferential surface of the stationary shaft and the first inner circumferential surface of the rotating portion includes a radial dynamic pressure groove array arranged to cause the lubricating oil to flow upward in a gap between the outer circumferential surface of the stationary shaft and the first inner circumferential surface of the rotating portion during rotation of the rotating portion;
• an upper surface of the lubricating oil is located between the outer circumferential surface of the first cup portion and the second inner circumferential surface of the rotating portion;
• a lower surface of the lubricating oil is located between the stationary and rotating portions at a level lower than that of the annular recessed portion;
• the rotating portion further includes a through hole filled with the lubricating oil, one end of the through hole opening into the annular recessed portion, an opposite end of the through hole opening into the gap between the stationary and rotating portions at a level lower than that of the annular recessed portion;
• and
• at least one of the circumferential surface of the first cup portion and the second inner circumferential surface of the rotating portion includes a pumping groove array arranged thereon to cause the lubricating oil to flow downward toward the lower end portion of the cylindrical portion during the rotation of the rotating portion.