FAN AND METHOD FOR MANUFACTURING THE SAME

Abstract

A fan includes a shaft, a hollow, approximately cylindrical rotor yoke that rotates around the shaft as a rotation axis and is open toward one of its axial ends, a rotor magnet secured to an inner circumference of the rotor yoke, and an impeller secured to an outer circumference of the rotor yoke and arranged to rotate together with the rotor yoke to generate an air flow. One of the impeller and the rotor yoke is provided with an index used for circumferentially positioning the impeller or the rotor yoke.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a fan according to a first preferred embodiment of the present invention.

FIG. 2 is a perspective view of a rotor in the fan of FIG. 1.

FIG. 3 is a perspective view of a rotor magnet in the fan of FIG. 1.

FIG. 4 is a perspective view illustrating in detail a rotor yoke assembly in the fan of FIG. 1.

FIG. 5 is a perspective view of a rotor yoke base according to the first preferred embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a combination of a rotor assembly and a jig according to the first preferred embodiment of the present invention.

FIG. 7 is a perspective view illustrating a combination of an impeller and an impeller base.

FIG. 8 is a cross-sectional view illustrating a combination of the impeller and the rotor assembly.

FIG. 9 is a perspective view illustrating a modified example of a rotor yoke index formed on the rotor yoke.

FIG. 10 is a perspective view illustrating a modified exemplary combination of the impeller and the impeller base.

FIG. 11 is a perspective view illustrating a die used for forming a rotor yoke by pressing.

FIG. 12 is a cross-sectional view illustrating the die used for forming the rotor yoke by pressing.

FIG. 13 is a perspective view illustrating a modified exemplary combination of the impeller and the impeller base.

FIG. 14 is a perspective view illustrating a modified exemplary combination of the impeller and the impeller base.

FIG. 15 is a perspective view illustrating a combination of an impeller and an impeller base according to a second preferred embodiment of the present invention.

Claims

1. A fan comprising: a shaft;a hollow, approximately cylindrical rotor yoke connected to the shaft and arranged to rotate around the shaft as a rotation axis;a rotor magnet secured to an inner circumference of the rotor yoke;an impeller secured to an outer circumference of the rotor yoke and arranged to rotate together with the rotor yoke to generate an air flow; whereinthe impeller is provided with an index arranged to circumferentially position the impeller.

2. The fan according to claim 1, wherein the impeller is hollow, and the rotor yoke is inserted into the impeller from an axial end of the impeller; andthe impeller has a surface at another axial end thereof, and the surface has at least one of a through hole, a concave portion, and a convex portion arranged therein or thereon as the index.

3. The fan according to claim 1, wherein the impeller is hollow, and the rotor yoke is inserted into the impeller from an axial end of the impeller;the impeller has a surface at another axial end thereof, and the surface has an approximately circular hole at its center centered about the rotation axis; andat least one of a notch and a projection is arranged on an inner edge of the surface of the impeller that defines the approximately circular hole, the notch being concave away from the rotation axis or the projection projecting toward the rotation axis.

4. A fan comprising: a shaft;a hollow, approximately cylindrical rotor yoke connected to the shaft and arranged to rotate around the shaft as a rotation axis;a rotor magnet secured to an inner circumference of the rotor yoke;an impeller attached to an outer circumference of the rotor yoke and arranged to rotate together with the rotor yoke to generate an air flow; whereinthe rotor yoke is provided with an index arranged to circumferentially position the rotor yoke.

5. The fan according to claim 4, wherein the rotor yoke is open toward an axial end, the rotor magnet is inserted into the rotor yoke from the one axial end; andat least one of a through hole, a concave portion, and a convex portion is formed at another axial end of the rotor yoke as the index.

6. The fan according to claim 5, wherein the rotor yoke is a pressed member with the index arranged therein or thereon.

7. The fan according to claim 4, wherein the rotor yoke is open toward an axial end, the rotor magnet is inserted into the rotor yoke from the axial end; anda notch is arranged on an edge of the rotor yoke at the axial end as the index.

8. The fan according to claim 7, wherein the rotor yoke is a pressed member with the notch arranged therein.

9. A method for manufacturing a fan including a shaft, a hollow, approximately cylindrical rotor yoke arranged to rotate around the shaft as a rotation axis, a rotor magnet secured to an inner circumference of the rotor yoke, and an impeller secured to an outer circumference of the impeller and arranged to rotate together with the rotor yoke to generate an air flow, the method comprising the steps of: a) measuring and correcting a rotation unbalance of the rotor yoke by itself and providing a rotor yoke index to locate a circumferential position of a portion causing the rotational unbalance of the rotor yoke;b) connecting the shaft to the rotor yoke;c) attaching the rotor magnet to the inner circumference of the rotor yoke;d) measuring a rotation unbalance of the rotor yoke with the rotor magnet and locating a position of a portion causing the rotation unbalance of the rotor yoke with the rotor magnet based on the rotor yoke index;e) measuring and correcting a rotation unbalance of the impeller by itself, and providing an impeller index to locate a circumferential position of a portion causing the rotation unbalance of the impeller; andf) making the rotation unbalance of the impeller and the rotation unbalance of the rotor yoke with the rotor magnet offset to each other based on the impeller index and the rotor yoke index, when the impeller and the rotor yoke are combined with each other.

10. The method according to claim 9, wherein the impeller is hollow, and the rotor yoke is inserted into the impeller from an axial end of the impeller when the rotor yoke and the impeller are combined with each other, and the step e) includes correcting the rotation unbalance of the impeller by providing at least one of a through hole, a concave portion, and a convex portion at another axial end of the impeller as the impeller index.

11. The method according to claim 9, wherein the impeller is hollow, the rotor yoke is inserted into the impeller from an axial end of the impeller, and the impeller has an approximately circular hole centered on the rotation axis at its other axial end, and the step e) includes correcting the rotation unbalance of the impeller by providing at least one of a notch and a projection on an inner edge of the impeller that defines the approximately circular hole, the notch being concave away from the rotation axis or the projection projecting toward the rotation axis, the at least one of the notch and the projection serving as the impeller index.

12. The method according to claim 9, wherein the step f) uses an impeller base on which the impeller is to be mounted when the impeller and the rotor yoke are combined with each other, the impeller base being provided with a positioning feature to correspond to the impeller index, the positioning feature of the impeller base being concave or convex, and the step f) includes fitting the impeller index of the impeller with the positioning feature of the impeller base to fix the portion of the impeller causing the rotation unbalance of the impeller at a specific circumferential position on the impeller base.

13. The method according to claim 9, wherein in the step b) the shaft is connected to an axial end of the rotor yoke, and the step a) includes correcting the rotation unbalance of the rotor yoke by providing at least one of a through hole, a concave portion, and a convex portion at the axial end of the rotor yoke to which the shaft is to be connected; the at least one of the through hole, the concave portion, and the convex portion serving as the rotor yoke index.

14. The method according to claim 13, wherein the rotor yoke is formed by pressing, and the step a) includes forming the at least one of the through hole, the concave portion, and the convex portion by pressing at a time of forming the rotor yoke by pressing.

15. The method according to claim 9, wherein the step a) includes correcting the rotation unbalance of the rotor yoke by providing at least one notch as the rotor yoke index on an edge of an open end of the rotor yoke.

16. The method according to claim 15, wherein the rotor yoke is formed by pressing, and the step a) includes forming the at least one notch by pressing at a time of forming the rotor yoke by pressing.

17. The method according to claim 14, wherein the rotor yoke is formed by a progressive pressing machine having a plurality of stages including a through-hole forming stage arranged to form the through hole in the rotor yoke, the through-hole forming stage including a plurality of holding portions each for holding a punching pin for forming a through hole, and the holding portions being circumferentially arranged about a center located on the rotation axis, and the step a) includes: measuring the rotation unbalance of the rotor yoke with no through hole; andcorrecting the rotation unbalance of the rotor yoke with no through hole by inserting a punching pin into a holding portion corresponding to the circumferential position of the portion causing the rotation unbalance of the rotor yoke with no through hole to form the through hole.

18. The method according to claim 9, wherein the step c) includes: bringing longitudinal ends of the rotor magnet into contact with each other to roll the rotor magnet with a joint formed by the longitudinal ends thereof; andoffsetting a weight unbalance at the joint of the rolled rotor magnet and the rotation unbalance of the rotor yoke from each other.

19. The method according to claim 9, wherein the step c) uses a base on which the rotor yoke is mounted when the rotor magnet and the rotor yoke are combined with each other, the base being provided with a positioning feature corresponding with the rotor yoke index, the positioning feature being concave or convex, and the step c) includes fitting the rotor yoke index with the positioning feature of the base to fix the circumferential position of the portion causing the rotation unbalance of the rotor yoke at a specific position by using the base.

20. The method according to claim 9, wherein the step f) uses a rotor attaching jig for securely holding the rotor yoke when the impeller and the rotor yoke are combined with each other, the rotor attaching jig being provided with a positioning feature corresponding to the rotor yoke index of the rotor yoke, the positioning feature being concave or convex, and the step f) includes fitting the rotor yoke index with the positioning feature to fix the circumferential position of the portion causing the rotation unbalance of the rotor yoke at a specific position by using the rotor attaching jig.