Spindle motor having a fluid dynamic bearing system and a stationary shaft

Patent metadata

Field	Value
Publication number	US-RE46300-E
Application number	US-201313946142-A
Country	US
Kind code	E1
Filing date	Jul 19, 2013
Priority date	Nov 30, 2007
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

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.

First claim

The invention claimed is:

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

Assignees

• Minebea Co Ltd

Inventors

• Popov Vladimir V
• Fleig Jürgen
• Bauer Martin
• Schmid Guido
• Winterhalter Olaf
• Wildpreth Matthias
• Fuss Thomas
• Engesser Martin
• Schwamberger Stefan

Classifications

• F16C17/107

  with at least one surface for radial load and at least one surface for axial load · CPC title

• F16C33/745 Primary

  by capillary action · CPC title

• F16C33/1085

  Channels or passages to recirculate the liquid in the bearing · CPC title

• F16C2370/12

  Hard disk drives or the like · CPC title

• H02K5/1677

  radially supporting the rotor around a fixed spindle; radially supporting the rotor directly · CPC title