Motor with rotor and stator dimensions for reducing cogging torque and torque ripple

• US 10,348,141 B2
• Filed: 09/15/2016
• Issued: 07/09/2019
• Est. Priority Date: 03/25/2010
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Li, Hu, Yoshikawa, Yuichi, Murakami, Hiroshi, Kado, Haruhiko, Kawamura, Kiyomi
• Primary Examiner(s): Truong, Thomas
• Assistant Examiner(s): Singh, Alexander A
• Application Number:
  US15/266,587
• Publication Number:
  US 20170005536A1
• Time in Patent Office: 1,027 Days
• Field of Search: 31015601, 310216001, 310216004, 310216074, 31015645, 310216097, 310216111, 310349, 310350, 310216092
• CPC Class Codes: H02K 1/146 consisting of a generally annular yoke with salient poles
• CPC Class Codes: H02K 1/16 Stator cores with slots for windings
• CPC Class Codes: H02K 1/165 Shape, form or location of the slots
• CPC Class Codes: H02K 1/2733 Annular magnets
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02K 2213/03 Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 3/18 Windings for salient poles

Abstract

A motor of this invention comprises a rotor having a permanent magnet, the number of which magnet poles is P, and a stator including M pcs of teeth, the teeth arranged in a circumferential direction in a manner to face the permanent magnet through a spatial gap, wherein the stator includes stator core having the number M of the teeth, and a winding wire wound about each of the tooth, wherein the number P of the magnet poles and the number M of the teeth have a relation defined by formulae (2/3)M<P<(4/3)M, and M≠P, and wherein ratio (t1/Ds) of teeth tip width t1 to stator inside diameter Ds is given by a formula 0.18<(t1/Ds)<0.25.

Claims

1. A motor comprising;

a rotor having a permanent magnet including a number of magnet poles P; and

a stator including a number of teeth M, the teeth arranged in a circumferential direction in a manner to face the permanent magnet through a spatial gap,

wherein the stator further includes a stator core having a number of teeth M and a winding wire wound about each of the teeth, wherein the stator core includes a ring-shape yoke and the teeth extruding inward from the yoke, the stator core being not divided core type but one piece core type;

wherein the rotor resides inside of the stator,

wherein a number the magnet poles P and a number of the teeth M are defined by P=10 and M=12, and

wherein a tooth tip width t1 is wider than the rest of the tooth among the number of teeth, the width of the tooth tip and stator inside diameter Ds are selected and sized such that a ratio (t1/Ds) of the tooth tip width t1 to a stator inside diameter Ds is given by a formula 0.18<

(t1/Ds)<

0.215, and

wherein a distance between the permanent magnet at a position facing the tooth tip and the tooth tip is constant.

2. The motor as listed in claim 1, wherein the stator core is structured by laminating a plurality of magnetic thin plates in a direction of thickness thereof.

3. An electric apparatus equipped with the motor listed in claim 2.

4. The motor as listed in claim 1, wherein the winding wire wound about the teeth has a space factor of at least 60%.

5. An electric apparatus equipped with the motor listed in claim 4.

6. The motor as listed in claim 1, wherein the stator is molded with a resin.

7. An electric apparatus equipped with the motor listed in claim 6.

8. The motor as listed in claim 1, wherein the permanent magnet is a ring type magnet.

9. An electric apparatus equipped with the motor listed in claim 8.

10. The motor as listed in claim 1, wherein the permanent magnet is a bonded rare earth magnet.

11. An electric apparatus equipped with the motor listed in claim 10.

12. The motor as listed in claim 1, wherein the permanent magnet is magnetized to have a surface magnetic flux of substantially a rectangular waveform in the circumferential direction.

13. An electric apparatus equipped with the motor listed in claim 12.

14. An electric apparatus equipped with the motor listed in claim 1.

15. The motor as listed in claim 1, wherein the permanent magnet is arranged to form the outer circumference of the rotor.