Hydrodynamic bearing, rotor device, and motor

A hydrodynamic bearing comprising:

• a hollow member having a hollow portion provided with at least one opening portion at least one end thereof;
• a rotating member disposed in said hollow portion so as to be rotatable relative to said hollow member and having a shaft portion extending through said opening portion;
• fluid interposed between said hollow portion and said rotating member;
• hydrodynamic pressure-producing means acting on said fluid between mutually opposite surfaces of said hollow member and said rotating member and producing hydrodynamic pressure with said opposite surfaces;
• and
• a seal portion for preventing leakage of said fluid from said opening portion;
• wherein said seal portion is formed by an inner diameter-varying portion and an outside diameter-varying portion, said inner diameter-varying portion being so formed that the inside diameter of said opening portion increases in going outwardly in an axial direction of said shaft portion, said outside diameter-varying portion being so formed that at least a part of the outside diameter of said shaft portion opposite to said inner diameter-varying portion decreases in going outwardly in said axial direction.