Abstract: A fluid dynamic pressure bearing has an annular dynamic pressure generating face having a dynamic pressure generating groove, which draws a working fluid toward a midway position in the radial direction from the inside and outside of a thrust bearing plate in the radial direction when a shaft and a housing are rotated relative to each other. The dynamic pressure generating groove is provided on thickness direction end faces of the thrust bearing plate or on an inner surface of the housing, and an inner groove section is located on an inner peripheral side of the dynamic pressure generating face on the end faces and is recessed more than the dynamic pressure generating face in the thickness direction. A through-hole extends through the thrust bearing plate in the thickness direction so as to open to the dynamic pressure generating face, and a communicating cavity connects the opening portion of the through-hole and the inner groove section.

Abstract: The generation of bubbles can be suppressed by enabling a stable supply of working fluid to a dynamic pressure generating groove, and oscillation at the time of rotation and leakage of working fluid can be prevented effectively by efficiently releasing any bubbles generated. There is provided a fluid dynamic pressure bearing 1 provided with an annular dynamic pressure generating face 17 made by forming a dynamic pressure generating groove, which draws a working fluid 14 toward a midway position in the radial direction from the inside and outside of a thrust bearing plate 13 in the radial direction, when a shaft 10 and a housing 11 are rotated relative to each other about the axis, on thickness direction end faces 13a, 13b of the thrust bearing plate 13, or on an inner surface of the housing 11, and an inner groove section 16, which is located on an inner peripheral side thereof and that is depressed more than the dynamic pressure generating face 17 in the thickness direction, on the end faces 13a, 13b.

Abstract: Disclosed is a fluid dynamic pressure bearing device rotatably supporting a shaft member by dynamic pressure of a liquid such as oil or water filling the clearance between the shaft member and a shaft member support portion, in which it is possible to maintain bearing properties of the fluid dynamic pressure bearing device for a long period of time.

Abstract: A reliable hydrodynamic bearing having high rotational accuracy is offered. The hydrodynamic bearing for a small-sized motor is made of a special nonmagnetic steel material that is excellent in terms of machinability, wear resistance, and corrosion resistance. This special steel material contains 14.00% Cr, 8.00% Mn, 0.20% C, 2.00% Ni, 0.35% Si, and less than 0.05% P. This special steel material has high machinability and so machining accuracies such as surface roughness and squareness can be enhanced. Consequently, the rotational accuracy of the hydrodynamic bearing can be enhanced. This special steel material also has such a property that when pressure is applied to plastically deform it, the pressed surface hardens. Using this nature, the surfaces at which rotating and stationary parts of the bearing contact with each other are pressed. Thus, the surfaces are hardened. Hence, the wear resistance is improved.

Abstract: A hydrodynamic bearing fitted with a seal portion capable of suppressing oil leakage efficiently is offered. Also, a rotor device and a motor using this bearing are offered. The seal portion is formed using a shaft-side tapering portion formed in a shaft and a sleeve-side tapering portion formed in an insertion hole in a sleeve. If the axis of rotation tilts when the shaft is at rest or during rotation, the interval between the outer surface of the shaft and the inner surface of the insertion hole decreases in the opening portion of the insertion hole. However, the two tapering portions secure a gap sufficient to hold oil within the hydrodynamic bearing if the interval decreases. Leakage of the oil from the opening portion of the insertion hole can be suppressed efficiently.

Abstract: A method for inserting fluid in a bearing device containing a fixed member and a rotating member. The fixed member and the rotating member of the bearing device are assembled in a high pressure environment and subsequently placed in a low pressure environment. While in the low pressure environment, bearing fluid is placed in a space between the fixed member and the rotating member. The fixed member and rotating member along with the bearing fluid are then placed in the high pressure environment to fully disperse the bearing fluid in the space between the fixed member and the rotating member.