Hydraulic dynamic bearing and spindle motor and rotary assembly provided

A fluid dynamic pressure bearing, comprising:

• a fixed shaft having at least one of a pair of ends fixedly mountable to an apparatus;
• a rotary sleeve having an inner peripheral surface arranged adjacent to an outer peripheral surface of the fixed shaft to provide a first fine gap between the inner peripheral surface of the rotary sleeve and the outer peripheral surface of the fixed shaft;
• a fixed sleeve having an outer peripheral surface arranged adjacent to an outer peripheral surface of the rotary sleeve to provide a second fine gap between an inner peripheral surface of the fixed sleeve and the outer peripheral surface of the rotary sleeve;
• and
• a lubrication oil filled in the fine gaps;
• wherein the first fine gap and the second fine gap each have one open end which is in contact with air outside the bearing and one closed end which is not in contact with the air, and the closed ends of the first and second fine gaps are in communication with each other through a third fine gap;
• and
• at least one of the first fine gap and the second fine gap are formed with a dynamic pressure producing groove and at least the other is formed with a drawing groove in such a manner that the grooves do not interfere with each other.

A fluid dynamic pressure bearing, comprising:

• a fixed shaft having at least one of a pair of ends fixedly mounted to an apparatus;
• a rotary sleeve having an inner peripheral surface arranged adjacent to an outer peripheral surface of the fixed shaft to provide a first fine gap between the inner peripheral surface of the rotary sleeve and the outer peripheral surface of the fixed shaft;
• a fixed sleeve having an inner peripheral surface arranged adjacent to an outer peripheral surface of the rotary sleeve to provide a second fine gap between the inner peripheral surface of the fixed sleeve and the outer peripheral surface of the rotary sleeve;
• and
• a lubrication oil filled in the fine gaps;
• wherein the first fine gap and the second fine gap each have one end which is in contact with air outside the bearing and one end which is not in contact with the air, and the closed ends of the first and second fine gaps are in communication with each other through a third fine gap;
• one or both of the first fine gap and the second fine gap are formed with a dynamic pressure producing groove;
• a capillary seal is provided in one or both of the open ends of the first fine gap and the second fine gap;
• and
• an auxiliary seal of a fluid reservoir type is formed in the fine gaps at which a capillary seal is provided at a position of the respective fine gap close to a portion of the capillary seal having a minimum groove width.

A bearing comprising:

• a fixed shaft having at least one end fixedly mountable to an apparatus;
• a rotary sleeve disposed about the fixed shaft so that a first fine gap is formed between an inner peripheral surface of the rotary sleeve and an outer peripheral surface of the fixed shaft;
• a fixed sleeve disposed about the rotary sleeve so that a second fine gap is formed between an inner peripheral surface of the fixed sleeve and an outer peripheral surface of the rotary sleeve;
• and a lubrication oil filled in the fine gaps;
• wherein the first fine gap and the second fine gap each have one open end which is in contact with air outside the bearing and one closed end which is not in contact with the air, and the closed ends of the first and second fine gaps are in communication with each other.