To obtain high moment stiffness and bearing stiffness while miniaturizing a dynamic pressure bearing device.
The bearing device is characterized in that a dynamic pressure generating portion 4 arranged in an inner surface of bearing member comprises a plurality of a first dynamic pressure groove 5 and a second dynamic pressure groove 6, in that the first dynamic pressure groove 5 comprises a short slant portion 7 forming a confluent portion 11 of fluid at downstream side and a long slant portion 8, in that a slant angle with respect to a circumferential direction line X1 of the short slant portion 7 is smaller than that of the long slant portion 8, in that the second dynamic pressure groove 6 comprises a short slant portion 9 forming a confluent portion 12 of the fluid at the downstream side and a long slant portion 10, in that a slant angle with respect to a circumferential direction line X2 of the short slant portion 9 is smaller than that of the long slant portion 10, in that the short slant portion 7 is arranged at an axial direction one end side(upper side) of the dynamic pressure generating portion 4 based on the confluent portion 11, and in that the short slant portion 9 is arranged at an axial direction the other end side (lower side) of the dynamic pressure generating portion 4 based on the confluent portion 12.
COPYRIGHT: (C)2007,JPO&INPIT
YAMAMOTO YASUHIRO
Hideka Tanaka
Yoshiyuki Shiraishi
Kunihiko Shiromura
Tsuyoshi Kumano
Hiroaki Yamane