Motor including hydrodynamic bearing and disk drive apparatus including same

A motor comprising:

• a rotating portion including a rotor magnet;
• and
• a stationary portion including a stator radially facing the rotor magnet;
• wherein
• the stationary portion includes:
• a shaft portion centered on a central axis;
• an upper plate portion extending radially outward from an upper portion of the shaft portion;
• and
• a lower plate portion extending radially outward from a lower portion of the shaft portion;
• the rotating portion includes a sleeve portion disposed between the upper plate portion and the lower plate portion;
• the sleeve portion includes:
• an inner sleeve cylindrical portion in which the shaft portion is inserted;
• a sleeve flange portion extending radially outward from a lower portion of the inner sleeve cylindrical portion;
• and
• an outer sleeve cylindrical portion extending upward from the sleeve flange portion;
• the upper plate portion includes:
• an upper plate cylindrical portion arranged farther outward than the inner sleeve cylindrical portion, facing an upper surface of the sleeve flange portion, and extending downward at an outer edge of the upper plate portion;
• and
• an upper plate connecting portion arranged to connect the shaft portion and the upper plate cylindrical portion in a region above the inner sleeve cylindrical portion;
• the lower plate portion includes:
• a lower plate cylindrical portion arranged farther outward than the outer sleeve cylindrical portion and extending upward at an outer edge of the lower plate portion;
• and
• a lower plate connecting portion arranged to connect the shaft portion and the lower plate cylindrical portion in a region below the sleeve flange portion;
• a lubricating oil is continuously arranged between the upper plate portion, the shaft portion, the lower plate portion, and the sleeve portion;
• an upper seal gap which opens upward is defined between an outer circumferential surface of the upper plate cylindrical portion and an inner circumferential surface of the outer sleeve cylindrical portion;
• an upper seal portion is arranged in the upper seal gap, a top surface of the lubrication oil being located in the upper seal portion;
• a lower seal gap which opens upward is defined between an outer circumferential surface of the outer sleeve cylindrical portion and an inner circumferential surface of the lower plate cylindrical portion;
• a lower seal portion is arranged in the lower seal gap, a bottom surface of the lubrication oil being located in the lower seal portion;
• a lower thrust dynamic pressure generating groove array is arranged on at least one surface of a lower surface of the sleeve flange portion and an upper surface of the lower plate connecting portion;
• a radial dynamic pressure generating groove array is arranged on at least one surface of an outer circumferential surface of the shaft portion and an inner circumferential surface of the inner sleeve cylindrical portion;
• and
• at least a portion of the upper seal portion and at least a portion of the lower seal portion radially overlap with a radial gap between the outer circumferential surface of the shaft portion and the inner circumferential surface of the inner sleeve cylindrical portion.