Spindle motor including magnetic element for pre-loading a ball bearing set
View Patent ↗A spindle motor for use in a disk drive includes a spindle motor base and a motor shaft. The motor shaft has a central axis. The spindle motor includes a spindle motor hub rotatably coupled to the spindle motor base, the spindle motor hub including a central magnetic metal portion disposed adjacent a distal end of the motor shaft. The spindle motor includes a ball bearing set disposed between and in mechanical communication with the spindle motor hub and the motor shaft for rotatably coupling the spindle motor hub to the spindle motor base. The spindle motor includes a shaft magnetic element attached to the motor shaft at the distal end adjacent the central magnetic metal portion, the shaft magnetic element being sized and configured to apply an attractive magnetic force to the central magnetic metal portion in a direction along the central axis for pre-loading the ball bearing set.
1. A spindle motor for use in a disk drive, the spindle motor comprising:
a spindle motor base;
a motor shaft in mechanical communication with the spindle motor base, the motor shaft having a central axis and a distal end;
a spindle motor hub rotatably coupled to the spindle motor base, the spindle motor hub including a central magnetic metal portion disposed adjacent the distal end;
a ball bearing set disposed between and in mechanical communication with the spindle motor hub and the motor shaft for rotatably coupling the spindle motor hub and the spindle motor base; and
a shaft magnetic element attached to the motor shaft at the distal end adjacent the central magnetic metal portion;
wherein the shaft magnetic element being sized and configured to apply an attractive magnetic force to the central magnetic metal portion in a direction along the central axis for pre-loading the ball bearing set.
2. The spindle motor of claim 1 wherein the central magnetic metal portion is formed of a magnetic steel material.
3. The spindle motor of claim 2 wherein the central magnetic metal portion is formed of a magnet.
4. The spindle motor of claim 1 wherein the central magnetic metal portion has a diameter greater than a diameter of the shaft magnet element about the central axis.
5. The spindle motor of claim 1 wherein the central magnetic metal portion is disk shaped.
6. The spindle motor of claim 1 wherein the motor shaft includes a distal opening at the distal end, the shaft magnetic element is disposed within the distal opening.
7. The spindle motor of claim 1 wherein the shaft magnetic element is cylindrical shaped.
8. The spindle motor of claim 1 wherein the motor shaft is integrally formed with the spindle motor base.
9. The spindle motor of claim 1 wherein the ball bearing set includes an inner race, the spindle motor further includes a magnetic path from the shaft magnetic element to the central magnetic metal portion to the inner race to the motor shaft to the shaft magnetic element.
10. A disk drive comprising:
a disk drive base; and
a spindle motor attached to the disk drive base, the spindle motor including;
a spindle motor base attached to the disk drive base;
a motor shaft in mechanical communication with the spindle motor base, the motor shaft having a central axis and a distal end;
a spindle motor hub rotatably coupled to the spindle motor base, the spindle motor hub including a central magnetic metal portion disposed adjacent the distal end;
a ball bearing set disposed between and in mechanical communication with the spindle motor hub and the motor shaft for rotatably coupling the spindle motor hub and the spindle motor base; and
a shaft magnetic element attached to the motor shaft at the distal end adjacent the central magnetic metal portion;
wherein the shaft magnetic element being sized and configured to apply an attractive magnetic force to the central magnetic metal portion in a direction along the central axis for pre-loading the ball bearing set.