Fluid dynamic-pressure bearing set for a fan

A fluid dynamic-pressure bearing set for a fan comprising:

• a casing having a hollow inner space;
• a seat integrally formed with the casing;
• the seat including a lower plate, and a hollow cylinder extended from the lower plate of the seat;
• a friction sheet being installed on the lower plate of the seat and being within the hollow cylinder of the seat;
• a bearing being installed around an inner periphery of the cylinder of the seat;
• a motor coil installed around an outer periphery of the cylinder of the seat;
• a rotary shaft installed in an axial center of the bearing;
• and
• a fan blade set installed at an upper portion of the rotary shaft;
• the upper portion of the rotary shaft protruding out of the bearing;
• and
• wherein a recess is formed on the lower plate of the seat and does not penetrate the bottom of the seat;
• and the recess is positioned between the friction sheet and an inner wall of the seat.