Eccentric rotor and vibration motor incorporating the eccentric rotor

1. A vibration motor, comprising:

a housing;

a stator received in the housing, comprising two claw-pole assemblies arranged back-to-back and a shaft being fixedly connected with the two claw-pole assemblies; and

a rotor being rotatably disposed in the stator, the rotor comprising a bearing being rotatably mounted around the shaft, a permanent magnet mounted around the bearing, and an eccentric weight being fixedly attached to the permanent magnet, the eccentric weight comprising a main body and at least one inserting portion having a density higher than that of the main body; and

wherein each claw-pole assembly comprises inner and outer yokes facing towards each other, a plurality of pole teeth extending from each of the yokes of each claw-pole assembly and being intermeshed with those of the other yoke, each outer yoke comprising a mounting portion concaved from a middle portion of each outer yoke towards the other outer yoke, the mounting portion defining a through hole with one end of the shaft being fixedly received therein and a plurality of mounting holes for resin being inserted therethrough to fill gaps between each two neighboring pole teeth.

2. The vibration motor of claim 1 , wherein the eccentric weight is sandwiched between the permanent magnet and the bearing.

3. The vibration motor of claim 1 , wherein the main body is made of one of the following materials: plastic, bakelite, aluminum, copper, aluminum alloy and copper alloy, and comprises a cylinder mounted around the bearing and a weight extending outwardly therefrom and being integrally formed with the cylinder, the inserting portion being received in the weight of the main body.

4. The vibration motor of claim 3 , wherein the at least one inserting portion is made of one of tungsten and tungsten alloy.

5. The vibration motor of claim 4 , wherein the at least one inserting portion is fixedly mounted in the weight of the main body by soldering.

6. The vibration motor of claim 3 , wherein the at least one inserting portion comprises several portions being symmetrically mounted in the weight.

7. The vibration motor of claim 1 , wherein the at least one inserting portion has one of the following shapes: column, cone, cuboid and irregular-shape.

8. The vibration motor of claim 1 , wherein the inner yokes of the two claw-pole assemblies abut against each other, each inner yoke forming at least a protrusion thereon and defining at least an aperture receiving the at least a protrusion of the other inner yoke therein.

9. The vibration motor of claim 1 , wherein the two claw-pole assemblies are mounted around the rotor symmetrically.

10. The vibration motor of claim 4 , wherein the at least one inserting portion is fixedly mounted in the weight of the main body by riveting.

11. The vibration motor of claim 4 , wherein the at least one inserting portion is fixedly mounted in the weight of the main body by interferential fitting.

12. The vibration motor of claim 1 , wherein an outer surface of the eccentric weight contacts an inner surface of the permanent magnet.

13. The vibration motor of claim 1 , wherein each inner yoke is ring-shaped with a circular hole defined therein, the bearing being received in the circular holes of the inner yokes and located between the outer yokes, a pair of spacers respectively arranged on top and bottom ends of the bearing for avoiding friction between the bearing and the outer yokes during rotation of the rotor.