Disk drive device provided with lubricant-filled fluid dynamic bearing

A disk drive device comprising:

• a hub having an outer circumferential wall portion configured to hold a recording disk;
• a base member having a cylindrical portion, whose central axis is the rotation axis of the hub, on a surface on the side of the hub;
• a fluid dynamic bearing configured to hold a lubricant and rotatably support the hub relative to the base member;
• a stator core having a ring portion fixed on the outer circumferential surface of the cylindrical portion and a plurality of salient poles extending in the radial direction from the ring portion;
• a coil wound around the plurality of salient poles;
• and
• a magnet fixed to the inner circumferential surface of the outer circumferential wall portion, the magnet being arranged to radially face the plurality of salient poles and provided along the circumferential direction with a plurality of magnetized poles for driving, wherein
• the fluid dynamic bearing has a boundary surface between a lubricant and air in an area formed between the base member and the hub,
• an opening of the cylindrical portion is provided on the outside of the boundary surface in the radial direction,
• the hub has a cylindrical hanging portion that faces the opening in the radial direction and forms a narrow gap portion with the opening,
• the dimension of the narrow gap portion in the radial direction is at most 0.2 mm and the dimension of the narrow gap portion in the axial direction is at least five times the dimension of the narrow gap portion in the radial direction.

A disk drive device comprising:

• a hub having an outer circumferential wall portion configured to hold a recording disk;
• a base member having a cylindrical portion, whose central axis is the rotation axis of the hub, on a surface on the side of the hub;
• a fluid dynamic bearing configured to hold a lubricant and rotatably support the hub relative to the base member;
• a stator core having a ring portion fixed on the outer circumferential surface of the cylindrical portion and a plurality of salient poles extending in the radial direction from the ring portion;
• a coil wound around the plurality of salient poles;
• and
• a magnet fixed to the inner circumferential surface of the outer circumferential wall portion, the magnet being arranged to radially face the plurality of salient poles and provided along the circumferential direction with a plurality of magnetized poles for driving;
• and
• wherein the surface of the base member on the side of the hub is provided with a circumferential wall portion surrounded by the outer circumferential wall portion,
• wherein the range of the outer circumferential wall portion in the axial direction overlaps the range of the circumferential wall portion in the axial direction,
• wherein a narrow gap portion in the axial direction with a radial dimension larger than an axial dimension is formed between the base member and the outer circumferential wall portion, and
• wherein a gap space in the radial direction is formed between the circumferential wall portion and the outer wall circumferential portion.