Fluid dynamic bearing system
View Patent ↗A fluid dynamic bearing system having a first conical bearing and a second conical bearing working in opposition to the first conical bearing, wherein the two conical bearings are disposed along a stationary shaft, wherein the first and the second conical bearing each comprises a bearing cone disposed on the shaft having bearing surfaces as well as a conical counter bearing disposed in a rotor component that are separated from one another by a bearing gap filled with a bearing fluid, wherein the bearing gap has a first open end that is sealed by a first sealing gap partially filled with bearing fluid, wherein the bearing fluid in the sealing gap forms a fluid meniscus. The sealing gap is bounded by sealing surfaces of the bearing cone and associated sealing surfaces of the rotor component, wherein the smallest radius R 1 of the sealing surfaces of the rotor component is larger than the largest outer radius R 2 of the bearing cone and larger than the greatest possible distance R 3 of the fluid meniscus from the rotational axis.
1. A fluid dynamic bearing system having a first conical bearing and a second conical bearing working in opposition to the first conical bearing, wherein the two conical bearings are disposed along a stationary shaft ( 12 , 212 ),
wherein the first and the second conical bearing each has:
a bearing cone ( 14 ; 114 ; 214 ; 314 ) disposed on the shaft having bearing surfaces ( 14 a ; 114 a ; 214 a ; 314 a );
a bearing component ( 215 ; 315 ; 16 ) having an annular rim ( 24 ; 124 ; 224 ; 324 ) that forms a conical counter bearing having bearing surfaces ( 215 a ; 315 a ; 16 a , 116 a ); a bearing gap ( 20 ; 120 ; 220 ; 320 ) filled with a bearing fluid that separates the bearing surfaces of the bearing cone and the bearing surfaces of the bearing component from one another; a first open end of the bearing gap ( 20 ; 120 ; 220 ; 320 ), a first sealing gap ( 22 ; 122 ; 222 ; 322 ) that is partially filled with bearing fluid and seals the first open end of the bearing gap, wherein the bearing fluid in the first sealing gap ( 22 ; 122 ; 222 ; 322 ) forms a fluid meniscus ( 23 ; 123 ; 223 ; 323 ),
characterized in that the first sealing gap ( 22 ; 122 ; 222 ; 322 ) is bounded by sealing surfaces ( 14 b ; 144 b ; 214 b ; 314 b ) of the bearing cone ( 14 ; 114 ; 214 ; 314 ) and associated sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 , 315 ; 16 ), wherein the smallest radius R 1 of the sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ) is larger than the largest outer radius R 2 of the bearing cone ( 14 ; 114 ; 214 ; 314 ) and larger than the greatest distance R 3 of the fluid meniscus ( 23 ; 123 ; 223 ; 323 ) from the rotational axis ( 42 ; 242 ).
2. A fluid dynamic bearing system according to claim 1 , characterized in that the sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ) are partially formed by the annular rim ( 24 ; 124 ; 224 ; 324 ), the smallest radius R 1 of the sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ) being disposed in the region of the rim ( 24 ; 124 ; 224 ; 324 ).
3. A fluid dynamic bearing system according to claim 1 , characterized in that the largest outer radius R 2 of the bearing cone ( 14 ; 114 ; 214 ; 314 ) is disposed in the transition region between its bearing surfaces ( 14 a ; 114 a ; 214 a ; 314 a ) and sealing surfaces ( 14 b ; 144 b ; 214 b ; 314 b ).
4. A fluid dynamic bearing system according to claim 1 , characterized in that the sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ) are inclined at least in the region of the rim ( 24 ; 124 ; 224 ; 324 ) at an angle α in the direction of the rotational axis ( 42 ; 242 ).
5. A fluid dynamic bearing system according to claim 4 , characterized in that the sealing surfaces ( 14 b ; 114 b ; 214 b ; 314 b ) of the bearing cone ( 14 ; 114 ; 214 ; 314 ) are inclined at an angle β in the direction of the rotational axis ( 42 ; 242 ).
6. A fluid dynamic bearing system according to claim 5 , characterized in that for angle α and β 0°<α<β applies.
7. A fluid dynamic bearing system according to claim 1 , characterized in that the bearing cone ( 14 ; 114 ; 214 ; 314 ) is covered by an annular covering cap ( 18 ; 118 ; 218 ; 318 ) that is disposed on the bearing component ( 215 ; 315 ; 16 ) at a distance to the bearing cone ( 14 ; 114 ; 214 ; 314 ) and encloses the shaft ( 12 ; 212 ) while forming an annular air gap.
8. A fluid dynamic bearing system according to claim 7 , characterized in that the covering cap ( 18 ; 118 ; 218 ; 318 ), together with the shaft ( 12 ; 212 ), forms a gap seal ( 34 ; 134 ).
9. A fluid dynamic bearing system according to claim 7 , characterized in that the covering cap ( 18 ; 118 ; 218 ; 318 ) is placed over and affixed on the rim ( 24 ; 124 ; 224 ; 324 ) of the bearing component ( 215 ; 315 ; 16 ).
10. A fluid dynamic bearing system according to claim 7 , characterized in that the rim ( 24 ) has an undercut ( 50 ) into which a circumferential bulge ( 52 ) on the covering cap ( 18 ) engages.
11. A fluid dynamic bearing system according to claim 1 , characterized in that the bearing gap ( 20 ; 120 ; 220 ; 320 ) has a second open end that is sealed by a second sealing gap ( 30 ; 130 ; 230 ; 330 ).
12. A fluid dynamic bearing system according to claim 11 , characterized in that the second sealing gap ( 30 ; 130 ; 230 ; 330 ) is bounded by sealing surfaces of the bearing cone ( 14 ; 114 ; 214 ; 314 ) and associated sealing surfaces of the bearing component ( 215 ; 315 ; 16 ).
13. A fluid dynamic bearing system according to claim 1 , characterized in that a central hole ( 46 ; 246 ) is disposed in the shaft ( 12 ; 212 ) that is connected to the outside atmosphere, wherein the second sealing gaps ( 30 ; 130 ; 230 ; 330 ) that end in the interior of the bearing system are vented by transversal holes ( 48 ; 248 ).
14. A fluid dynamic bearing system according to claim 1 , characterized in that a recirculation channel ( 26 ; 126 ; 226 ; 326 ) is disposed in the bearing cone ( 14 ; 114 ; 214 ; 314 ), the recirculation channel ( 26 ; 126 ; 226 ; 326 ) connecting the first sealing gap ( 22 ; 122 ; 222 ; 322 ) directly to the second sealing gap ( 30 ; 130 ; 230 ; 330 ).
15. A fluid dynamic bearing system according to claim 1 , characterized in that the first conical bearing is formed symmetric to the second conical bearing.
16. A spindle motor having a stator, a rotor, an electromagnetic drive system and a fluid dynamic bearing system having a first conical bearing and a second conical bearing working in opposition to the first conical bearing, wherein the two conical bearings are disposed along a stationary shaft ( 12 , 212 ),
wherein the first and the second conical bearing each has:
a bearing cone ( 14 ; 114 ; 214 ; 314 ) disposed on the shaft having bearing surfaces ( 14 a ; 114 a ; 214 a ; 314 a );
a bearing component ( 215 ; 315 ; 16 ) having an annular rim ( 24 ; 124 ; 224 ; 324 ) that forms a conical counter bearing having bearing surfaces ( 215 a ; 315 a ; 16 a , 116 a ); a bearing gap ( 20 ; 120 ; 220 ; 320 ) filled with a bearing fluid that separates the bearing surfaces of the bearing cone and the bearing surfaces of the bearing component from one another; a first open end of the bearing gap ( 20 ; 120 ; 220 ; 320 ), a first sealing gap ( 22 ; 122 ; 222 ; 322 ) that is partially filled with bearing fluid and seals the first open end of the bearing gap, wherein the bearing fluid in the first sealing gap ( 22 ; 122 ; 222 ; 322 ) forms a fluid meniscus ( 23 ; 123 ; 223 ; 323 ),
characterized in that the first sealing gap ( 22 ; 122 ; 222 ; 322 ) is bounded by sealing surfaces ( 14 b ; 144 b ; 214 b ; 314 b ) of the bearing cone ( 14 ; 114 ; 214 ; 314 ) and associated sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ), wherein the smallest radius R 1 of the sealing surfaces ( 215 b ; 315 b ; 16 b ; 116 b ) of the bearing component ( 215 ; 315 ; 16 ) is larger than the largest outer radius R 2 of the bearing cone ( 14 ; 114 ; 214 ; 314 ) and larger than the greatest distance R 3 of the fluid meniscus ( 23 ; 123 ; 223 ; 323 ) from the rotational axis ( 42 ; 242 ).
17. A disk drive having a spindle motor according to claim 16 , at least one storage disk ( 54 ) driven by the spindle motor and means for reading and/or writing data off and to the storage disk ( 54 ).