US 7,531,928 B2
Spindle motor and rotation device having dynamic pressure bearing
Takeyoshi Yamamoto, Ehime (Japan)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan)
Filed on Jun. 30, 2006, as Appl. No. 11/477,546.
Claims priority of application No. 2005-300032 (JP), filed on Oct. 14, 2005.
Prior Publication US 2007/0085432 A1, Apr. 19, 2007
Int. Cl. H02K 5/16 (2006.01); H02K 7/08 (2006.01); F16C 17/10 (2006.01); G11B 17/02 (2006.01)
U.S. Cl. 310—90  [310/67 R; 360/99.07; 360/99.08; 384/112] 16 Claims
OG exemplary drawing
 
1. A spindle motor comprising:
a shaft including a core spindle member with a large diameter portion and a small diameter portion and an encircling annulus member attached to the small diameter portion;
a rotor hub attached to an outer peripheral surface of the large diameter portion;
a bearing member including a removal inhibiting member and a bottom surface, wherein the bearing member is provided with a bearing bore closed at one end and opened at another end and having an inner peripheral surface radially confronting with an outer peripheral surface of the encircling annulus member;
fluid filled in a gap between the shaft and the bearing member;
a radial bearing portion formed between the outer peripheral surface of the encircling annulus member and the inner peripheral surface of the bearing member, wherein first dynamic pressure creating grooves are formed on at least one thereof;
a thrust bearing portion formed between a lower end surface of the encircling annulus member and the bottom surface of the bearing member, wherein second dynamic pressure creating grooves are formed on at least one thereof;
a first opening formed at a radially inner side of the thrust bearing portion and opened in an axial direction;
a second opening formed at a radially outer side of the large diameter portion in the vicinity of the removal inhibiting member and opened radially outwardly; and
a communication hole continuously formed from the first opening to the second opening.