Production method of vibrating motor and rotor for vibrating motor
View Patent ↗A vibrating motor has a shaft, a stator including a yoke having pole teeth extending toward an axis of the shaft from an inner circumference and coils wound around the pole teeth, a rotor including an eccentric weight formed on a radially outer surface of the shaft, and a permanent magnet integrally formed with the eccentric weight, and a bearing device rotatably supporting the rotor maintaining clearance between the inner circumference of the pole teeth and the rotor. The rotor has a structure in which the shaft, the eccentric weight, and the permanent magnet are integrally formed with each other by a thermoplastic magnetic material composing the permanent magnet.
1. A vibrating motor comprising:
a shaft,
a stator including a yoke having pole teeth extending toward an axis of the shaft from an inner circumference and coils wound around the pole teeth;
a rotor including an eccentric weight formed on a radially outer surface of the shaft, and a permanent magnet integrally formed with the eccentric weight;
a bearing device rotatably supporting the rotor maintaining clearance between the inner circumference of the pole teeth and the rotor;
wherein the rotor has a structure in which the shaft, the eccentric weight and the permanent magnet are integrally formed with each other by a thermoplastic magnetic material composing the permanent magnet.
2. The vi rating motor according to claim 1 , wherein the rotor is formed by insertion molding of the thermoplastic magnetic material composing the permanent magnet, and the shaft and the eccentric weight are used as materials for the insertion.
3. The vibrating motor according to claim 1 , wherein an outermost axial length of the rotor, excluding an axial length of the shaft, is smaller than an outermost radial length of the rotor.
4. The vibrating motor according to claim 1 , wherein the eccentric weight extends as far as a radially outer surface of the permanent magnet.
5. The vibrating motor according to claim 1 , wherein a concavity is formed at a peripheral portion of the shaft in the eccentric weight, and a part of the bearing is disposed in the concavity.
6. The vibrating motor according to claim 1 , wherein the shaft is connected to the eccentric weight by a connecting portion, and the connecting portion is formed by the thermoplastic magnetic material composing the permanent magnet.
7. The vibrating motor according to claim 6 , wherein the connecting portion has a tubular structure, the shaft contacts an inner surface of the tubular structure, and the eccentric weight contacts an outer surface of the tubular structure.
8. The vibrating motor according to claim 7 , wherein the connecting portion has a polygonal shape when viewed from an axial direction.
9. The vibrating motor according to claim 1 , wherein the eccentric weight overlaps with the pole teeth when viewed from an axial direction.
10. The vibrating motor according to claim 9 , wherein a portion of the eccentric weight overlapping with the pole teeth, when viewed from an axial direction, is formed on both sides of the eccentric weight, when viewed from a direction perpendicular to the axial direction.
11. The vibrating motor according to claim 1 , wherein the eccentric weight overlaps with the coils when viewed from an axial direction.
12. The vibrating motor according to claim 11 , wherein a portion of the eccentric weight overlapping with the coils, when viewed from an axial direction, is formed on both sides of the eccentric weight, when viewed from a direction perpendicular to the axial direction.
13. A production method for a rotor for a vibrating motor comprising:
preparing a shaft, an eccentric weight and a mold;
disposing the shaft and the eccentric weight in the mold; and
integrally forming the shaft, the eccentric weight and a permanent magnet by injecting a thermoplastic magnetic material into the mold.