Fluid dynamic bearing unit and disk drive device including the same

Abstract

A first sleeve rotatably extends around a shaft. First and second flanges are fixed to the shaft. A second sleeve extending around the first sleeve is fixed thereto. A first annular member fixed to the second sleeve surrounds the first flange. A second annular member fixed to the second flange surrounds a portion of the second sleeve. A first capillary seal includes a clearance between the first flange and the first annular member. A second capillary seal includes a clearance between the second annular member and the second sleeve. Lubricant is provided in the clearances in the first and second capillary seals. The second annular member and the second sleeve are designed so that the lubricant in the clearance in the second capillary seal can be viewed from a point in a radial position which is outward of the second sleeve as seen in an axial direction.

1 - 22 . (canceled) 
     
     
         23 . A disk drive device comprising:
 a base that comprises:
 a core supporting portion that supports a stator core around which a coil is wound; and 
 a bottom portion that includes a coil opposing portion facing with the coil in an axial direction, the bottom portion being integrally formed with the core supporting portion, 
   a rotator which is supported at an upper side of the base in a freely rotatable manner and which comprises:
 a mounting portion on which a recording disk is to be mounted; and 
 a shaft enclosure, 
   a shaft assembly that comprises:
 an upper flange that comprises a first opposing portion facing with an upper end of the shaft enclosure in the axial direction; 
 a lower flange; and 
 a portion fixed to the base, the lower flange comprising:
 a second opposing portion facing with a lower end of the shaft enclosure in the axial direction; and 
 an annular portion that comprises a first portion facing with the core in a radial direction to form a first gap therebetween, a second portion facing with an upper end of the core supporting portion in the axial direction to form a second gap therebetween, and a third portion facing with the shaft enclosure to form a third gap therebetween; and 
 
   a radial dynamic pressure generating groove provided in at least one of the shaft assembly and the shaft enclosure.   
     
     
         24 . The disk drive device according to  claim 23 , wherein:
 the lower flange further comprises a downward projection that projects downwardly in the axial direction from the second opposing portion; and   the annular portion, the second opposing portion, and the downward projection are formed integrally one another.   
     
     
         25 . The disk drive device according to  claim 24 , wherein the downward projection comprises a portion inserted in a hole which is formed in the base and which is formed inwardly relative to the core supporting portion in the radial direction. 
     
     
         26 . The disk drive device according to  claim 24 , wherein the downward projection is formed with a hole into which a portion of a shaft is inserted. 
     
     
         27 . The disk drive device according to  claim 23 , wherein:
 a thrust dynamic pressure generating groove is formed in at least one of the lower flange and the shaft enclosure; and   the second portion is located downwardly in the axial direction relative to the thrust dynamic pressure generating groove.   
     
     
         28 . The disk drive device according to  claim 23 , wherein the second opposing portion of the lower flange has a thinner thickness than a maximum thickness of the coil opposing portion of the base. 
     
     
         29 . The disk drive device according to  claim 23 , wherein:
 the shaft enclosure is provided with a radial-direction recess in an outer circumference of the shaft enclosure; and   a tapered space is formed in an outer circumference of the radial-direction recess.   
     
     
         30 . The disk drive device according to  claim 23 , wherein:
 the core supporting portion comprises an annular wall that protrudes toward the rotator from the bottom portion in the axial direction;   the stator core comprises an annular part; and   an inner circumference of the annular part comprises a portion contacting the annular wall, and a non-contact portion with the annular wall, the non-contact portion being successively provided from the portion contacting the annular wall at the hub side in the axial direction.   
     
     
         31 . A disk drive device comprising:
 a base that comprises:
 a core supporting portion that supports a stator core around which a coil is wound; and 
 a bottom portion that includes a coil opposing portion facing with the coil in an axial direction, the bottom portion being integrally formed with the core supporting portion, 
   a rotator which is supported at an upper side of the base in a freely rotatable manner and which comprises:
 a mounting portion on which a recording disk is to be mounted; and 
 a shaft enclosure, 
   a shaft assembly that comprises:
 a lower flange that comprises:
 a shaft-enclosure opposing portion facing with a lower end of the shaft enclosure in the axial direction; and 
 an annular portion that comprises a first portion facing with the core in a radial direction to form a first gap therebetween, and a second portion facing with an upper end of the core supporting portion in the axial direction to form a second gap therebetween, the annular portion being formed separately from the core supporting portion; and 
 
   a radial dynamic pressure generating groove provided in at least one of the shaft assembly and the shaft enclosure.   
     
     
         32 . The disk drive device according to  claim 31 , wherein:
 the lower flange further comprises a downward projection that projects downwardly in the axial direction from the shaft-enclosure opposing portion; and   the annular portion, the shaft-enclosure opposing portion, and the downward projection are formed integrally one another.   
     
     
         33 . The disk drive device according to  claim 32 , wherein the downward projection comprises a portion inserted in a hole which is formed in the base and which is formed inwardly relative to the core supporting portion in the radial direction. 
     
     
         34 . The disk drive device according to  claim 32 , wherein the downward projection is formed with a hole into which a portion of a shaft is inserted. 
     
     
         35 . The disk drive device according to  claim 31 , wherein:
 a thrust dynamic pressure generating groove is formed in at least one of the lower flange and the shaft enclosure; and   the second portion is located downwardly in the axial direction relative to the thrust dynamic pressure generating groove.   
     
     
         36 . The disk drive device according to  claim 31 , wherein the shaft-enclosure opposing portion of the lower flange has a thinner thickness than a maximum thickness of the coil opposing portion of the base. 
     
     
         37 . The disk drive device according to  claim 31 , wherein:
 the shaft enclosure is provided with a radial-direction recess in an outer circumference of the shaft enclosure; and   a tapered space is formed in an outer circumference of the radial-direction recess.   
     
     
         38 . The disk drive device according to  claim 31 , wherein:
 the core supporting portion comprises an annular wall that protrudes toward the rotator from the bottom portion in the axial direction;   the stator core comprises an annular part; and   an inner circumference of the annular part comprises a portion contacting the annular wall, and a non-contact portion with the annular wall, the non-contact portion being successively provided from the portion contacting the annular wall at the hub side in the axial direction.   
     
     
         39 . A disk drive device comprising:
 a base that comprises:
 a core supporting portion that supports a stator core around which a coil is wound; and 
 a bottom portion that includes a coil opposing portion facing with the coil in an axial direction, the bottom portion being integrally formed with the core supporting portion, 
   a rotator which is supported at an upper side of the base in a freely rotatable manner and which comprises:
 a mounting portion on which a recording disk is to be mounted; and 
 a shaft enclosure, 
   a shaft assembly that comprises:
 a lower flange that comprises:
 a shaft-enclosure opposing portion facing with a lower end of the shaft enclosure in the axial direction; and 
 an annular portion that comprises a portion facing with an upper end of the core supporting portion in the axial direction to form a gap therebetween, the annular portion being formed separately from the core supporting portion; and 
 
   a radial dynamic pressure generating groove provided in at least one of the shaft assembly and the shaft enclosure.   
     
     
         40 . The disk drive device according to  claim 39 , wherein:
 the lowerflange further comprises a downward projection which projects downwardly in the axial direction from the shaft-enclosure opposing portion, and which is formed with a hole where an end of a shaft is inserted;   the annular portion, the shaft-enclosure opposing portion, and the downward projection are formed integrally one another; and   the downward projection comprises a portion inserted in a hole which is formed in the base and which is formed inwardly relative to the core supporting portion in the radial direction.   
     
     
         41 . The disk drive device according to  claim 39 , wherein the shaft-enclosure opposing portion of the lower flange has a thinner thickness than a maximum thickness of the coil opposing portion of the base. 
     
     
         42 . The disk drive device according to  claim 39 , wherein:
 the core supporting portion comprises an annular wall that protrudes toward the rotator from the bottom portion in the axial direction;   the stator core comprises an annular part; and   an inner circumference of the annular part comprises a portion contacting the annular wall, and a non-contact portion with the annular wall, the non-contact portion being successively provided from the portion contacting the annular wall at the hub side in the axial direction.