Magnetoelectric generator

1. A magnetoelectric generator comprising:

a bowl-shaped flywheel having a cylindrical portion and a bottom portion;

a plurality of permanent magnets fixed to an inner peripheral wall surface of said cylindrical portion so as to be arranged circumferentially;

a resin material filled between adjacent pairs of said permanent magnets, said resin material fixing said permanent magnets integrally to said flywheel;

a stator core disposed radially inside said flywheel such that an outer peripheral surface of said stator core faces said permanent magnets; and

a generating coil configured by winding a conducting wire onto said stator core,

said magnetoelectric generator generating electric power by electromagnetic induction between said permanent magnets and said generating coil due to rotation of said flywheel,

wherein:

a plurality of press-worked protrusions, which forcibly increase roundness of said flywheel, are formed by press working on said bottom portion of said flywheel.

2. The magnetoelectric generator according to claim 1 , wherein:

a retaining portion for preventing displacement relative to said resin material is formed on said cylindrical portion by press working.

3. The magnetoelectric generator according to claim 1 , wherein:

said bottom portion is work-hardened by press working; and

a ventilating aperture is formed on said bottom portion.

4. The magnetoelectric generator according to claim 1 , wherein:

a cooling fin connected to said resin material and projecting radially inward from said resin material is disposed on said bottom portion.

5. The magnetoelectric generator according to claim 1 , wherein:

at least one press-worked protrusion has a different shape from other press-worked protrusions among said press-worked protrusions.

6. The magnetoelectric generator according to claim 1 , wherein the plurality of protrusions are formed at a uniform pitch on said bottom portion of said flywheel.

7. The magnetoelectric generator according to claim 1 , further comprising a plurality of retaining portions formed by press-working and wherein the plurality of protrusions are formed in a vicinity of the retaining portions.

8. The magnetoelectric generator according to claim 7 , wherein for each of the retaining portions, a corresponding protrusion from the plurality of protrusions is provided in a vicinity of the retaining portion.

9. The magnetoelectric generator according to claim 1 , where the protrusions protrude inward by applying press working on a surface of said bottom portion of the flywheel on a side opposite from a stator.

10. The magnetoelectric generator according to claim 1 , wherein the protrusions protrude outward by press working from a surface of the bottom portion of said flywheel on a side near a stator.

11. The magnetoelectric generator according to claim 10 , further comprising a plurality of retaining portions formed by press working, wherein the plurality of retaining portions project radially outward from an inner peripheral wall surface of the cylindrical portion of the flywheel.

12. The magnetoelectric generator according to claim 1 , further comprising a plurality of ventilating apertures formed on said bottom portion of the flywheel, wherein the plurality of protrusions are formed between the plurality of ventilating apertures by press working from a surface of said bottom of said flywheel on a side opposite from a stator.

13. The magnetoelectric generator according to claim 1 , further comprising a plurality of swivel stopping grooves at uniform pitch at a peripheral edge portion on a surface of said bottom portion on a side near a stator, wherein the plurality of swivel stopping grooves prevent the resin material from rotating relative to said flywheel.

14. The magnetoelectric generator according to claim 13 , further comprising a dislodgement-preventing groove formed around an entire circumference on an inner peripheral wall surface of the cylindrical portion of the flywheel, wherein the dislodgement-preventing groove prevents the resin material from dislodging axially.

15. A method for creating a round bowl-shaped flywheel of a magnetoelectric generator comprising:

machining material into a bowl-shaped flywheel;

press working the bowl-shaped flywheel to form retaining portions; and

re-press working a bottom portion of the flywheel to form protrusions.

16. The method according to claim 15 , wherein when the retaining portions are formed, roundness of the flywheel deteriorates and wherein, when the protrusions are formed, said deterioration is corrected.