Motor

Abstract

An object of the present invention is to provide a motor capable of enhancing the balance correction effect and capable of keeping the balance correction effect for a long term.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view in an axial direction of an embodiment of a motor of the present invention.

FIG. 2 is a schematic cross sectional view in the axial direction of a rotary unit of the present invention.

FIG. 3 is a schematic cross sectional view in the axial direction of a state where a balance correction of the motor of the present invention is carried out.

FIG. 4 is a bottom view of the motor of the present invention in the axial direction of the mounting plate as viewed from a lower surface.

FIG. 5 is a schematic cross sectional view in the axial direction of a state where a balance correction is carried out in a state where a color wheel and a clamp member are mounted on the motor of the present invention.

FIG. 6 is a flowchart showing a balance correcting method of the present invention.

FIG. 7 is a schematic cross sectional view in the axial direction of another embodiment of the motor of the present invention.

Claims

1. A motor comprising: a rotor unit rotatable about a central axis, including, a rotor magnet, anda rotor hub having a notch at which a portion of the rotor hub is removed, including a hub cylindrical portion having a substantially hollow, cylindrical shape centered on the central axis, a radial extension radially outwardly extending from an axially lower portion of the hub cylindrical portion; anda stator unit supporting the rotor unit in a rotatable manner and including a stator having a surface radially facing the rotor magnet,wherein the notch is arranged in at least one of a radially outside surface of the hub cylindrical portion and an axially lower surface of the radial extension to correct a rotational balance of the rotor unit.

2. The motor as set forth in claim 1, wherein the notch is a portion at which the rotor hub is cut.

3. The motor as set forth in claim 2, wherein the rotor unit further includes a substantially annular groove centered on the central axis and circumferentially extending from the notch in at least one of the axially lower surface of the radial extension and the radially outside surface of the hub cylindrical portion.

4. The motor as set forth in claim 2, wherein the notch is the portion at which a substantially cylindrical part of the rotor hub is removed.

5. The motor as set forth in claim 1, wherein: the stator unit further includes a sleeve which is arranged at a radially inside the hub cylindrical portion;the rotor hub includes an inner peripheral cylindrical portion radially inwardly extending at an axially upper end portion of the rotor hub, a radially inner side end thereof is arranged radially inner from a radially outer end of the sleeve; andthe notch is arranged at a portion, a radially outside the inner peripheral cylindrical portion, of the radially outside surface of the hub cylindrical portion.

6. The motor as set forth in claim 1, wherein the rotor unit further includes a circumferential wall and a first balance correcting member, the circumferential wall axially upwardly extends from an radially outside portion of an axially upper end of the hub cylindrical portion of the rotor hub, and the first balance correcting member is arranged at a radially inner side of the circumferential wall to correct the rotational balance of the rotor unit.

7. The motor as set forth in claim 6, wherein the rotor unit further includes a magnet holding section and a second balance correcting member, the magnet holding section supports the rotor magnet at a radially inner side face thereof and has an axially lower end portion arranged axially lower than that of the rotor magnet, the second balance correcting member is arranged at a position near from the axially lower end portions of the magnet holding section and the rotor magnet to correct the rotational balance of the rotor unit.

8. The motor as set forth in claim 7, wherein the stator unit further includes a mounting plate having a mounting plate notch, the mounting plate is arranged an axially lower than the stator, and the mounting plate notch is a through hole axially penetrating the mounting plate arranged axially below the axially lower end portion of the magnet holding section.

9. The motor as set forth in claim 1, wherein the rotor unit further includes a magnet holding section and a second balance correcting member, the magnet holding section supports the rotor magnet at a radially inner side face thereof and has an axially lower end portion arranged axially lower than that of the rotor magnet, the second balance correcting member is arranged at a position near from the axially lower end portions of the magnet holding section and the rotor magnet to correct the rotational balance of the rotor unit.

10. The motor as set forth in claim 9, wherein the stator unit further includes a mounting plate having a mounting plate notch, the mounting plate is arranged axially lower than the stator, and the mounting plate notch is a through hole axially penetrating the mounting plate arranged axially below the axially lower end portion of the magnet holding section.

11. The motor as set forth in claim 1, wherein the stator unit rotatably supports the rotor unit by using gas dynamic pressure.

12. A manufacturing method of the motor as set forth in claim 1, comprising the steps of: preparing the rotor unit including the rotor hub;preparing the stator unit to support the rotor unit in the rotatable manner;arranging the rotor unit on the stator unit such that the rotor unit is rotatable about the central axis; andproviding the notch to the rotor hub to correct the rotational balance of the rotor unit,wherein the notch is provided to the rotor hub before the rotor unit is arranged on the stator unit.

13. The manufacturing method as set forth in claim 12 further comprising a step of providing a substantially annular groove centered on the central axis to the rotor hub, wherein the notch is provided to the rotor hub by using a cutting tool, a tip end of the cutting tool is positioned within the annular groove for providing the notch.

14. The motor as set forth in claim 1 further comprising a color wheel arranged on the rotor hub.

15. The manufacturing method of the motor as set forth in claim 14, comprising the steps of: preparing the rotor unit including the rotor hub having a circumferential wall axially upwardly extends from a radially outside portion of an axially upper end of the hub cylindrical portion;preparing the stator unit to support the rotor unit in the rotatable manner;arranging the rotor unit on the stator unit such that the rotor unit is rotatable about the central axis;providing the notch in at least one of the lower surface of the radial extension and the radially outside surface of the hub cylindrical portion to correct the rotational balance of the rotor unit;arranging the color wheel on the rotor hub; andarranging a first balance correcting member at the rotor hub,wherein the notch is provided to the rotor hub before the color wheel is arranged on the rotor hub, and the first balance correcting member is arranged at radially inner side of the circumferential wall to correct the rotational balance of the rotor unit after arranging the color wheel on the rotor hub.

16. The method of manufacturing the motor as set forth in claim 15, further comprising the steps of: providing a clamp member having a circumferential wall axially upwardly extending from radially outside portion thereof, sandwiching the color wheel with the rotor hub to fix the color wheel on the rotor hub,arranging a third balance correcting member at a radially inner side of the circumferential wall of the clamp member to correct the rotational balance of the rotor unit.

17. The manufacturing method as set forth in claim 14, comprising the steps of: preparing the rotor unit including the rotor hub having a circumferential wall axially upwardly extends from an radially outside portion of an axially upper end of the hub cylindrical portion and a magnet holding section supporting the rotor magnet at a radially inner side face thereof and having an axially lower end portion arranged axially lower than that of the rotor magnet;preparing the stator unit to support the rotor unit in the rotatable manner, and including a mounting plate having a mounting plate notch axially penetrating the mounting plate;arranging the rotor unit on the stator unit such that the rotor unit is rotatable about the central axis and the mounting plate notch is arranged axially below the axially lower end portions of the magnet holding section and the rotor magnet;providing the notch in at least one of the lower surface of the radial extension and the radially outside surface of the hub cylindrical portion correct the rotational balance of the rotational balance of the rotor unit;arranging the color wheel on the rotor hub; andarranging a first balance correcting member at a radially inner side of the circumferential wall of the rotor unit,arranging a second balance correcting member at a position near from the axially lower end portions of the magnet holding section and the rotor magnetwherein the first balance correcting member and the second balance correcting member are arranged to correct the rotational balance of the rotor unit after arranging the color wheel on the rotor hub.

18. A motor comprising: a rotor unit rotatable about a central axis, including, a rotor magnet,a rotor unit having a hub cylindrical portion having a substantially hollow, cylindrical shape centered on the central axis,a radial extension radially outwardly extending from the axially lower portion of the hub cylindrical portion,a circumferential wall axially upwardly extends from an radially outside portion of an axially upper end of the hub cylindrical portion, anda magnet holding section supporting the rotor magnet at a radially inner side face thereof and having an axially lower end portion arranged axially lower than that of the rotor magnet,a first balance correcting member arranged at a radially inner side of the circumferential wall, anda second balance correcting member arranged at a portion near from the axially lower end portions of the magnet holding section and the rotor magnet; anda stator unit supporting the rotor unit in a rotatable manner and including a stator having a surface radially facing the rotor magnet,wherein the first balance correcting member and the second balance correcting member together correct a rotational balance of the rotor unit.

19. The motor as set forth in claim 18, wherein amounting plate having a mounting plate notch, the mounting plate is arranged an axially lower than the stator, and the mounting plate notch is a through hole axially penetrating the mounting plate arranged axially below the second balance correcting member.

20. The motor as set forth in claim 18, wherein the rotor unit further includes: a color wheel arranged on the rotor hub;a clamp member having a circumferential wall axially upwardly extending from a radially outside portion thereof, sandwiching the color wheel with the rotor hub to fix the color wheel on the rotor hub; anda third balance correcting member arranged at a radially inner side of the circumferential wall of the clamp member to correct the rotational balance of the rotor unit.

21. The motor as set forth in claim 18, wherein the stator unit rotatably supports the rotor unit by using gas dynamic pressure.