SINGLE-PHASE BRUSHLESS MOTOR

• US 20150042194A1
• Filed: 08/08/2014
• Published: 02/12/2015
• Est. Priority Date: 08/09/2013
• Status: Active Grant

• Current Assignee: Johnson Electric International AG (Johnson Electric Holdings Limited)
• Original Assignee: Johnson Electric SA 125 Rue de Progres La Chaux de Fonds Switzerland (Johnson Electric Holdings Limited)
• Inventors: LI, Yue, LIU, Bao Ting, ZHOU, Chui You, WANG, Yong, CHEN, Ming, ZHU, Xiao Ning
• Granted Patent: US 10,110,076 B2
• Time in Patent Office: Days
• US Class Current: 310/156.01
• CPC Class Codes: H02K 1/16 Stator cores with slots for windings
• CPC Class Codes: H02K 1/2706 Inner rotors
• CPC Class Codes: H02K 21/00 Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02K 2201/03 Machines characterised by aspects of the air-gap between rotor and stator
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems

Abstract

A single-phase brushless motor includes a stator and a rotor rotatable with respect to the stator. The rotor includes a number of permanent magnetic poles. The stator includes a stator core and a winding wound on the stator core. The stator core includes an outer annular portion, an inner annular portion, and connecting portions connecting the inner and outer annular portions. The winding is wound around the connecting portions. The rotor is received in the inner annular portion. The inner annular portion and the rotor form a substantially uniform air gap. A recess is formed in an inner surface of a part of the inner annular portion between each pair of adjacent connecting portions. A center of each recess deviates from a center line of symmetry of the corresponding pair of connecting portions.

Claims

1. A single-phase brushless motor comprising a stator and a rotor rotatable with respect to the stator, the rotor comprising a rotor core having a plurality of permanent magnetic poles, the stator comprising a stator core and a winding wound on the stator core, the stator core comprising an outer annular portion, an inner annular portion, and a plurality of connecting portions connecting the inner annular portion to the outer annular portion, the winding being wound around the connecting portions, the rotor being received in the inner annular portion;

wherein the inner annular portion of the stator and the rotor form a substantially uniform air gap therebetween, an inner surface, which faces the rotor, of a part of the inner annular portion between every two adjacent ones of the connecting portions is formed with a recess, and a center of each recess is offset from a middle line between corresponding two adjacent ones of the connecting portions.

2. The single-phase brushless motor of claim 1, wherein the inner surface of the inner annular portion is located on a circle concentric with the rotor.

3. The single-phase brushless motor of claim 1, wherein a magnetic bridge is formed at the part of the inner annular portion between every two adjacent ones of the connecting portions.

4. The single-phase brushless motor of claim 3, wherein the magnetic bridge comprises a groove formed in an outer surface of the inner annular portion.

5. The single-phase brushless motor of claim 3, wherein the magnetic bridge comprises an aperture or hole formed in the inner annular portion.

6. The single-phase brushless motor of claim 1, wherein the number of recesses is equal to the number of connecting portions and equal to the number of magnetic poles of the rotor.

7. The single-phase brushless motor of claim 1, wherein the connecting portions are separately formed with respect to one or both of the inner annular portion and the outer annular portion.

8. The single-phase brushless motor of claim 1, wherein the recesses run through the inner surface of the inner annular portion along an axial direction of the motor.

9. The single-phase brushless motor of claim 1, wherein the recesses are spacingly disposed in the inner surface of the inner annular portion along an axial direction of the motor.

10. The single-phase brushless motor of claim 1, wherein the motor has a start up angle which is in a range of 60 to 80 degrees electrical angle.

11. A single-phase brushless motor comprising:

a stator comprising a stator core and a winding wound on the stator core, the stator core comprising an outer annular portion, an inner annular portion, and a plurality of connecting portions connected between the inner annular portion and the outer annular portion, the winding being wound around the connecting portions; and

a rotor being received in the inner annular portion and rotatable with respect to the stator, the rotor comprising a plurality of permanent magnetic poles, wherein the rotor and the inner annular portion of the stator form a substantially uniform air gap therebetween, an inner surface, which faces the rotor, of a part of the inner annular portion between every two adjacent connecting portions is formed with a recess, and the recess is configured and arranged such that the rotor is capable of being started in two directions.

12. The single-phase brushless motor of claim 11, wherein a center of each recess is offset from a middle line between corresponding two adjacent connecting portions.

13. The single-phase brushless motor of claim 12, wherein an offset angle formed between the center of each recess and the middle line between corresponding two adjacent connecting portions is in a range of 45 to 135 degrees electrical angle.

14. The single-phase brushless motor of claim 11, wherein the inner surface of the inner annular portion is located on a circle concentric with the rotor.

15. The single-phase brushless motor of claim 11, wherein a magnetic bridge is formed in the part of the inner annular portion between every two adjacent connecting portions.

16. The single-phase brushless motor of claim 15, wherein the magnetic bridge comprises a groove formed in an outer surface of the inner annular portion.

17. The single-phase brushless motor of claim 15, wherein the magnetic bridge comprises an aperture or hole formed in the inner annular portion.

18. The single-phase brushless motor of claim 11, wherein the number of recesses is equal to the number of connecting portions and equal to the number of magnetic poles of the rotor.

19. The single-phase brushless motor of claim 11, wherein the connecting portions are separately formed with respect to one or both of the inner annular portion and the outer annular portion.

20. The single-phase brushless motor of claim 11, wherein the rotor further comprises a rotor core and the plurality of permanent magnetic poles is formed by one or more permanent magnets mounted on a radially outer surface of the rotor core.