Brushless motor

• US 8,338,999 B2
• Filed: 07/16/2008
• Issued: 12/25/2012
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Takeuchi, Kesatoshi, Nakamura, Kazuyoshi, Sugimoto, Mamoru
• Primary Examiner(s): Leung, Quyen
• Assistant Examiner(s): Mok, Alex W
• Application Number:
  US12/174,165
• Publication Number:
  US 20090033166A1
• Time in Patent Office: 1,623 Days
• Field of Search: 310/68.R, 310/67.R
• US Class Current: 310/68.R
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: H02K 11/215 Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 7/14 Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06

Abstract

The brushless motor includes a stator having a electromagnetic coil and a position sensor; an axis fixed to the stator; and a rotor having a permanent magnet. The rotor rotates around the axis. The rotor is linked to a driven member that is driven by the brushless motor.

Claims

1. A brushless motor driving a driven member, comprising:

a round-disk shaped stator having a plurality of phase-A coils and a plurality of phase-B coils;

an axis fixed to the stator;

a rotor rotating around the axis and linked to the driven member, the rotor having a first round-disk shaped rotor and a second rotor connected to the first rotor, the first rotor and the second rotor sandwiching the stator therebetween, the first rotor being positioned on one side of the stator and including first magnets, the second rotor being positioned on another side of the stator and including second magnets;

a wiring coupled to the brushless motor, the wiring being provided through an inside of a part of the axis; and

a magnetic yoke made of a ferromagnetic body, the magnetic yoke being disposed on outside faces of the first and second magnets;

wherein the phase-A coils and the phase-B coils are positioned at locations phase-shifted by π

/2 from each other;

wherein the phase-A coils and the phase-B coils have no magnetic core;

the number of the first magnets is equal to the number of the phase-A coils;

the number of the second magnets is equal to the number of the phase-B coils;

the first magnets are each positioned at a constant magnetic pole pitch, with adjacent magnets being magnetized in opposite directions;

the second magnets are each positioned at a constant magnetic pole pitch, with adjacent magnets being magnetized in opposite directions;

the first magnets and the second magnets are positioned with their magnetic poles which face towards the stator having mutually different polarity;

the magnetic pole pitch of the first magnets and the second magnets is equal to a coil pitch of the phase-A coils and the phase-B coils;

a magnetic field of the first and second magnets is directed perpendicularly through the stator; and

AC drive signals are delivered to the phase-A coils and the phase-B coils.

2. The brushless motor according to claim 1, further comprising,

a regenerating circuit that regenerates power from the phase-A coils and the phase-B coils.

3. The brushless motor according to claim 1, wherein

the phase-A coils and the phase-B coils are coated with resin.

4. A device, comprising:

the brushless motor according to claim 1; and

the driven member that is driven by the brushless motor.

5. The device according to claim 4, wherein

the device is a movable body.

6. The movable body according to claim 5, wherein

the movable body is a railway vehicle.

7. The brushless motor according to claim 1, wherein

the rotor enwraps the round-disk shaped stator, and

the first magnets and the second magnets are provided at an inside of the rotor.