Patent ID: 8315011

Claim:
A disk drive device comprising: a base member; a bearing unit arranged on the base member and configured to rotatably support a recording disk relative to the base member; and a drive unit configured to rotationally drive the recording disk to be supported by the bearing unit, wherein the bearing unit includes: a shaft to be the center of the rotation; a sleeve having a housing portion for housing the shaft and configured to allow relative rotation, with the shaft as the axis; a radial space portion defined by both the inner wall surface of the housing portion of the sleeve and the outer wall surface of the shaft; a radial dynamic pressure groove formed on at least one of the inner wall surface of the sleeve and the outer wall surface of the shaft so as to generate radial dynamic pressure, the two wall surfaces defining the radial space portion; a flange projected in the radial direction of the shaft and configured to rotate integrally with the shaft; a flange housing space portion defined by the flange surrounding wall portion and configured to rotatably house the flange, the flange surrounding wall portion being formed continuously from the sleeve and outwards in the radial direction of the flange; a counter plate structured with both a first surface, which faces an end surface in the axial direction of the flange and seals the flange housing space portion, and a second surface that is opposite to the first surface; a thrust dynamic pressure groove formed on both of at least one of surfaces of the flange and the flange housing space portion, which face each other in the thrust direction, and at least one of surfaces of the flange and the first surface of the counter plate, and configured to generate thrust dynamic pressure; and lubricant that is filled in the radial space portion and the flange housing space portion, wherein a projected dimension of the flange is larger than a wall thickness of the flange surrounding wall portion in the radial direction of the flange, wherein the sleeve has a fitting section that receives the counter plate in order to seal the flange housing space portion by the counter plate, wherein the fitting section has a first concave portion, which is hollow in the radial direction of the shaft so as to include a part of an area between the position that corresponds to the outer edge corner portion on the second surface side of the counter plate and the position that corresponds to the outer edge corner portion on the first surface side of the counter plate, wherein the counter plate is fit into and fixed in the fitting section such that the outer edge corner portion on the second surface side matches the hollow area of the first concave portion, and wherein adhesive is applied, between the counter plate and the fitting section, along the circumferential portion of the counter plate.