Spindle motor having a fluid dynamic bearing system and a stationary shaft
View Patent ↗The invention relates to a spindle motor having a fluid dynamic bearing system comprising axial and radial bearings that contains a rotor component ( 14 ) which encloses a stationary shaft ( 12 ), which in turn is connected at both its ends to axially aligned bearing parts ( 16; 18 ) that are fashioned such that they form capillary sealing gaps ( 32; 34 ), a recirculation channel ( 28 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and an electromagnetic drive system ( 42, 44 ) for driving the rotor component.
1. A spindle motor having a fluid dynamic bearing system comprising:
a stationary shaft ( 12 ; 212 ; 312 ) that is held directly or indirectly in a baseplate ( 10 , 210 ; 310 ),
a rotor component ( 14 , 114 a ; 214 ; 314 a - c ) rotatably supported with respect to the shaft about a rotational axis ( 46 ; 246 ; 346 ),
a bearing gap ( 20 , 220 ; 320 ) open at both ends filled with a bearing fluid that separates the adjoining surfaces of the shaft ( 12 ; 212 ; 312 ), the rotor component ( 14 , 114 a ; 214 ; 214 a - c ) and at least one first bearing part ( 16 , 216 ; 316 ) from one another, a first radial bearing ( 22 a , 222 a ; 322 a ) and a second radial bearing ( 22 b , 222 b ; 322 b ) formed between the opposing axially extending bearing surfaces of the shaft ( 12 ; 212 ; 312 ) and the rotor component ( 14 , 114 a ; 214 ; 314 a - c ),
an axial bearing ( 26 , 226 ; 326 ) formed between the opposing radially extending bearing surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) and the first bearing part ( 16 , 216 ; 316 ) connected to the baseplate,
a recirculation channel ( 28 ; 128 ; 228 ; 328 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and
an electromagnetic drive system ( 42 , 44 ; 342 , 244 ) for driving the rotor component, and
characterized in that the recirculation channel ( 28 , 128 ; 228 ) ends in a gap ( 21 ) radially outside of the bearing gap ( 20 ) of the axial bearing ( 26 ), the width of the gap ( 21 ) being greater than the width of the bearing gap ( 20 ).
2. A spindle motor according to claim 1 , characterized in that the rotor component consists of an inner, sleeve-shaped rotor component ( 114 a ; 314 a ) and an outer cup-shaped rotor component ( 144 b ; 314 b ).
3. A spindle motor according to claim 2 , characterized in that the inner, sleeve-shaped rotor component ( 314 a ) is enclosed by a further, sleeve-shaped rotor component ( 314 c ) on which the outer cup-shaped rotor component ( 314 b ) is disposed.
4. A spindle motor according to claim 1 , characterized in that it only contains one rotating, mechanical rotor component ( 14 ; 214 ) taking the form of a hub/bearing bush arrangement.
5. A spindle motor according to claim 1 , characterized in that the first bearing part ( 216 ) is integrally formed with the shaft ( 212 ) as one piece.
6. A spindle motor according to claim 1 , characterized in that a second bearing part ( 18 ; 318 ) is integrally formed with the shaft ( 12 ) as one piece.
7. A spindle motor according to claim 1 , characterized in that the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) has surfaces that are fashioned such that, together with surfaces of the second bearing part ( 18 ; 218 ; 318 ), they form a sealing gap ( 32 ; 232 ; 332 ) of a capillary gap seal.
8. A spindle motor according to claim 1 , characterized in that the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) has surfaces that are fashioned such that, together with surfaces of a first bearing part ( 16 ; 216 ; 316 ), they form a sealing gap ( 34 ; 234 ; 334 ) of a capillary gap seal.
9. A spindle motor according to claim 1 , characterized in that the recirculation channel ( 328 ) is disposed in the rotor component ( 314 a ) or between the rotor components ( 314 a , 314 c ) and connects the sealing gap ( 334 ) radially outside the axial bearing ( 226 ) to a section of the bearing gap ( 320 ) located radially outside a dynamic pumping seal.
10. A spindle motor according to claim 1 , characterized in that the recirculation channel ( 28 , 128 ; 228 ) is disposed at an incline to the rotational axis ( 46 ), which, on rotation of the rotor component, causes a centrifugal force to be exerted on the bearing fluid held in the recirculation channel, the centrifugal force transporting the bearing fluid through the recirculation channel ( 28 , 128 ; 228 ) in the direction of arrow ( 29 ).
11. A spindle motor according to claim 10 , characterized in that the recirculation channel ( 28 , 128 ; 228 ) is inclined at an angle of 5 to 15 degrees with respect to the rotational axis ( 46 ).
12. A spindle motor according to claim 10 , characterized in that the centrifugal force exerted on the bearing fluid due to the inclined recirculation channel ( 28 , 128 ; 228 ) acts in the same direction as a pumping force exerted on the bearing fluid due to an overall pumping effect of the axial bearing ( 26 ; 126 ; 226 ; 326 ) and the radial bearings ( 22 a , 22 b ; 122 a , 122 b ; 222 a , 222 b ; 322 a , 322 b ).
13. A spindle motor according to claim 12 , characterized in that the pumping force generated by the centrifugal force is directed to the axial bearing ( 26 ).
14. A spindle motor according to claim 12 , characterized in that the centrifugal force is at least twice as big as the force exerted on the bearing fluid due to the overall pumping effect of the axial bearing ( 26 ) and the radial bearings ( 22 a , 22 b ).
15. A spindle motor according to claim 1 , characterized in that a dynamic pumping seal ( 36 ; 236 ; 336 ) is formed between opposing radially extending surfaces of the rotor component ( 14 , 114 ; 214 ; 314 ) and a second bearing part ( 18 ; 218 ; 318 ) connected to the shaft.
16. A spindle motor according to claim 15 , characterized in that the dynamic pumping seal ( 36 ; 236 ; 336 ) is formed between a radially extending end face of the rotor component ( 14 , 114 a ; 214 ; 314 a ) and an adjoining radially extending end face of the second bearing part ( 18 ; 218 ; 318 ).
17. A spindle motor according to claim 15 , characterized in that the dynamic pumping seal ( 36 ; 236 ; 336 ) is disposed substantially perpendicular and the sealing gap ( 32 ; 232 ; 332 ) of the gap seal substantially parallel to the rotational axis ( 46 ; 246 ; 346 ).
18. A spindle motor according to claim 1 , characterized in that the baseplate ( 10 ; 310 ) has a ferromagnetic ring ( 40 ; 340 ) that lies axially opposite a rotor magnet ( 44 ; 344 ) of the electromagnetic drive system and is magnetically attracted by this magnet and that they generate a magnetic force that is directed in the opposite direction to a bearing force generated by the axial bearing ( 26 ; 326 ).
19. A spindle motor according to claim 18 , characterized in that the electromagnetic drive system comprises a stator arrangement ( 42 ; 342 ) which is disposed at an axial offset with respect to the rotor magnet ( 44 ; 344 ) and generate a magnetic force that is directed in the opposite direction to a bearing force generated by the axial bearing ( 26 ; 326 ).
20. A spindle motor according to claim 1 , characterized in that adjacent surfaces of the second bearing part ( 18 ) and the rotor component 14 form a further axial bearing ( 25 ).
21. A spindle motor according to claim 1 , characterized in that a further bearing part ( 19 ) connected to the rotor component adjoins the second bearing part ( 18 ), a pumping seal ( 36 ) being disposed between the two bearing parts ( 18 , 19 ) and a sealing gap being disposed between the bearing part ( 19 ) and the shaft ( 12 ).
22. A spindle motor having a fluid dynamic bearing system comprising:
a stationary shaft ( 12 ; 212 ; 312 ) that is held directly or indirectly in a baseplate ( 10 , 210 ; 310 ),
a rotor component ( 14 , 114 a ; 214 ; 314 a - c ) rotatably supported with respect to the shaft about a rotational axis ( 46 ; 246 ; 346 ),
a bearing gap ( 20 , 220 ; 320 ) open at both ends filled with a bearing fluid that separates the adjoining surfaces of the shaft ( 12 ; 212 ; 312 ), the rotor component ( 14 , 114 a ; 214 ; 214 a - c ) and at least one first bearing part ( 16 , 216 ; 316 ) from one another, a first radial bearing ( 22 a , 222 a ; 322 a ) and a second radial bearing ( 22 b , 222 b ; 322 b ) formed between the opposing axially extending bearing surfaces of the shaft ( 12 ; 212 ; 312 ) and the rotor component ( 14 , 114 a ; 214 ; 314 a - c ),
an axial bearing ( 26 , 226 ; 326 ) formed between the opposing radially extending bearing surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) and the first bearing part ( 16 , 216 ; 316 ) connected to the baseplate,
a recirculation channel ( 28 ; 128 ; 228 ; 328 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and
an electromagnetic drive system ( 42 , 44 ; 342 , 244 ) for driving the rotor component,
characterized in that the recirculation channel ( 28 , 128 ; 228 ) ends in a gap ( 21 ) radially outside of the bearing gap ( 20 ) of the axial bearing ( 26 ), and
further characterized in that the width of the gap ( 21 ) is greater than or equal to the width of the bearing gap ( 20 ) of the axial bearing ( 26 ) plus the depth of the bearing patterns of the axial bearing ( 26 ).
23. A spindle motor having a fluid dynamic bearing system comprising:
a stationary shaft ( 12 ; 212 ; 312 ) that is held directly or indirectly in a baseplate ( 10 , 210 ; 310 ),
a rotor component ( 14 , 114 a ; 214 ; 314 a - c ) rotatably supported with respect to the shaft about a rotational axis ( 46 ; 246 ; 346 ),
a bearing gap ( 20 , 220 ; 320 ) open at both ends filled with a bearing fluid that separates the adjoining surfaces of the shaft ( 12 ; 212 ; 312 ), the rotor component ( 14 , 114 a ; 214 ; 214 a - c ) and at least one first bearing part ( 16 , 216 ; 316 ) from one another, a first radial bearing ( 22 a , 222 a ; 322 a ) and a second radial bearing ( 22 b , 222 b ; 322 b ) formed between the opposing axially extending bearing surfaces of the shaft ( 12 ; 212 ; 312 ) and the rotor component ( 14 , 114 a ; 214 ; 314 a - c ),
an axial bearing ( 26 , 226 ; 326 ) formed between the opposing radially extending bearing surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) and the first bearing part ( 16 , 216 ; 316 ) connected to the baseplate,
a recirculation channel ( 28 ; 128 ; 228 ; 328 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and
an electromagnetic drive system ( 42 , 44 ; 342 , 244 ) for driving the rotor component, and
a sealing gap ( 32 ; 332 ) for sealing the bearing gap ( 20 , 220 ; 320 ) which is covered by an annular cover ( 30 , 130 ; 330 ) connected to the rotor component ( 14 ; 114 a ; 314 c ) that, together with the second bearing part ( 18 ; 318 ), forms a labyrinth seal ( 48 ; 348 ).
24. A spindle motor according to claim 23 , characterized in the annular cover ( 330 ) is formed by the rotor component.
25. A spindle motor according to claim 23 , characterized in that the sealing gap ( 32 ) is formed between an inner circumferential surface of the cover ( 130 ) and an outer circumferential surface of the second bearing part ( 18 ).
26. A spindle motor according to claim 23 , characterized in that the sealing gap ( 32 ; 332 ) is formed between an inner circumferential surface/end face of the rotor component ( 14 , 114 a ; 214 ; 314 a ; 314 c ) and an outer circumferential surface/end face of the second bearing part ( 18 ; 218 ; 318 ).
27. A spindle motor according to claim 23 , characterized in that the sealing gap ( 34 ; 234 ; 334 ) is formed between an outer circumferential surface of the rotor component ( 14 , 114 a ; 214 ; 314 a ; 314 c ) and an inner circumferential surface of the first bearing part ( 16 ; 216 ; 316 ).
28. A spindle motor according to claim 23 , characterized in that surfaces of the rotor component ( 14 , 144 a ; 214 ) or the cover ( 130 ) and the second bearing part ( 18 ; 218 ) forming the sealing gap ( 32 ; 232 ) extend substantially parallel to the rotational axis ( 46 ; 246 ) or are inclined at an acute angle to the rotational axis.
29. A spindle motor according to claim 23 , characterized in that surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a ; 314 c ) and the first bearing part ( 16 ; 216 ; 316 ) forming the sealing gap ( 34 ; 234 ; 334 ) extend substantially parallel to the rotational axis ( 46 ; 246 ; 346 ) or are inclined at an acute angle to the rotational axis.
30. A hard disk drive comprising a spindle motor for rotatably driving at least a storage disk, and means for writing on and reading data from the storage disk, the spindle motor having a fluid dynamic bearing system and comprising:
a stationary shaft ( 12 ; 212 ; 312 ) that is held directly or indirectly in a baseplate ( 10 , 210 ; 310 ),
a rotor component ( 14 , 114 a ; 214 ; 314 a - c ) rotatably supported with respect to the shaft about a rotational axis ( 46 ; 246 ; 346 ),
bearing gap ( 20 , 220 ; 320 ) open at both ends filled with a bearing fluid that separates the adjoining surfaces of the shaft ( 12 ; 212 ; 312 ), the rotor component ( 14 , 114 a ; 214 ; 214 a - c ) and at least one first bearing part ( 16 , 216 ; 316 ) from one another, a first radial bearing ( 22 a , 222 a ; 322 a ) and a second radial bearing ( 22 b , 222 b ; 322 b ) formed between the opposing axially extending bearing surfaces of the shaft ( 12 ; 212 ; 312 ) and the rotor component ( 14 , 114 a ; 214 ; 314 a - c ),
an axial bearing ( 26 , 226 ; 326 ) formed between the opposing radially extending bearing surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) and the first bearing part ( 16 , 216 ; 316 ) connected to the baseplate,
a recirculation channel ( 28 ; 128 ; 228 ; 328 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and
an electromagnetic drive system ( 42 , 44 ; 342 , 244 ) for driving the rotor component,
characterized in that the recirculation channel ( 28 , 128 ; 228 ) ends in a gap ( 21 ) radially outside of the bearing gap ( 20 ) of the axial bearing ( 26 ), and
further characterized in that the width of the gap ( 21 ) is greater than or equal to the width of the bearing gap ( 20 ) of the axial bearing ( 26 ) plus the depth of the bearing patterns of the axial bearing ( 26 ).
31. A spindle motor having a fluid dynamic bearing system comprising:
a stationary shaft ( 12 ; 212 ; 312 ) that is held directly or indirectly in a baseplate ( 10 , 210 ; 310 ),
a rotor component ( 14 , 114 a ; 214 ; 314 a - c ) rotatably supported with respect to the shaft about a rotational axis ( 46 ; 246 ; 346 ),
a bearing gap ( 20 , 220 ; 320 ) open at both ends filled with a bearing fluid that separates the adjoining surfaces of the shaft ( 12 ; 212 ; 312 ), the rotor component ( 14 , 114 a ; 214 ; 214 a - c ) and at least one first bearing part ( 16 , 216 ; 316 ) from one another, a first radial bearing ( 22 a , 222 a ; 322 a ) and a second radial bearing ( 22 b , 222 b ; 322 b ) formed between the opposing axially extending bearing surfaces of the shaft ( 12 ; 212 ; 312 ) and the rotor component ( 14 , 114 a ; 214 ; 314 a - c ),
an axial bearing ( 26 , 226 ; 326 ) formed between the opposing radially extending bearing surfaces of the rotor component ( 14 , 114 a ; 214 ; 314 a - c ) and the first bearing part ( 16 , 216 ; 316 ) connected to the baseplate,
a recirculation channel ( 28 ; 128 ; 228 ; 328 ) filled with bearing fluid that connects the remote regions of the bearing to each other, and
an electromagnetic drive system ( 42 , 44 ; 342 , 244 ) for driving the rotor component,
characterized in that the recirculation channel ( 28 , 128 ; 228 ) is disposed in the rotor component ( 14 ; 114 a ; 214 ) and connects a sealing gap ( 34 ) radially outside the axial bearing ( 26 ) to a section of the bearing gap ( 20 ) adjacent to a dynamic pumping seal ( 136 ).