Fluid dynamic pressure bearing device, spindle motor provided with the fluid dynamic pressure bearing device, and recording disk drive device with the fluid dynamic pressure bearing device

A fluid dynamic pressure bearing device, comprising:

• a shaft member including a first end that attaches to a base member of a motor;
• a bearing member that engages a rotor hub of the motor, a micro gap being formed between the shaft member and the bearing member;
• a shaft member-side annular member engaged with the shaft member, the shaft member-side annular member including a first end surface that contacts the base member of the motor, an outer circumferential surface of the shaft member-side annular member including a step and/or a taper that reduces in diameter progressing toward the first end surface;
• a bearing member-side annular member that engages with the bearing member and/or with the rotor hub of the motor, an inner circumferential surface of the bearing member-side annular member including a step and/or a taper that reduces in diameter progressing toward the base member of the motor;
• the outer circumferential surface of the shaft member-side annular member and the inner circumferential surface of the bearing member-side annular member facing each other and being adjacent to each other in an axial direction and in a radial direction;
• a capillary seal portion that suppresses lubricant occupying the micro gap from leaking being formed between the shaft member-side annular member and the bearing member-side annular member;
• at least one first dynamic pressure groove formed in either an outer circumferential surface of the shaft member or an inner circumferential surface of the bearing member, the at least one first dynamic pressure groove generating a radial dynamic pressure receiving a load in a radial direction;
• and
• at least one second dynamic pressure groove formed in either a second end surface of the shaft member-side annular member facing the bearing member or an end surface of the bearing member facing the second end surface of the shaft member-side annular member, the at least one second dynamic pressure groove generating a thrust dynamic pressure receiving a load in a thrust direction.