Permanent magnet electric generator

• US 5,767,601 A
• Filed: 12/13/1996
• Issued: 06/16/1998
• Est. Priority Date: 12/19/1995
• Status: Expired due to Fees

• Current Assignee: Mitsuba Corporation
• Original Assignee: Mitsuba Corporation
• Inventors: Uchiyama, Hidekazu
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): TAMAI, KARL I
• Application Number:
  US08/766,726
• Time in Patent Office: 550 Days
• Field of Search: 310/113, 310/156, 310/209, 310/181, 310/67 R, 310/198, 310/190, 310/191, 310/153
• US Class Current: 310/190
• CPC Class Codes: H02K 21/046 with rotating permanent magnets and stationary field winding

Abstract

A permanent magnet electric generator has a raised output as compared with the output of a similar conventional permanent magnet generator in which the polar arcuate angle of the permanent magnets is equal to the polar arcuate angle of controlling magnetic poles. Electricity is generated in armature coils 16 by the rotation of permanent magnets 8 of a rotor 4. Controlling magnetic poles 9 formed of a magnetic material are interposed between the permanent magnets 8 of the rotor 4, and a field controlling coil 17 is provided on a stator 11. The value of the polar arcuate angle θ m of the permanent magnets 8 divided by the sum of the polar arcuate angle θ m of the permanent magnets 8 plus the polar arcuate angle θ p of the controlling magnetic poles 9 is set at 0.55 to 0.7. The generator provides an increased output as compared with a permanent magnet generator having the same physique as that of a generator in which all field magnetic poles of the rotor 4 are constituted by permanent magnets and wherein the polar arcuate angle θ m of the permanent magnets 8 is equal to the polar arcuate angle θ p of the controlling magnetic poles 9.

Claims

1. A permanent magnet electric generator comprising:

a stator having a plurality of stator poles wound with armature coils and having a central axis and one axial side,

a rotor supported for rotation relative to said stator about said central axis and carrying permanent magnets arranged at intervals in a direction circumferential to said central axis and arranged concentrically of said central axis on a yoke formed of a magnetic material,

said yoke having a cylindrical rim portion radially outwardly surrounding said magnets and a bottom portion located outboard of said one axial side of said stator and between said central axis and said rim portion,

said generator being constructed such that electricity is generated in the armature coils by the rotation of said rotor in relation to said stator,

said rotor including controlling magnetic poles formed of magnetic material interposed between said permanent magnets of said rotor,

said permanent magnets forming same magnetic poles cooperating with said stator poles,

a field controlling coil, and

means supporting said field controlling coil in a fixed position relative to said stator and in a space formed between said stator and said bottom portion of said yoke such that magnetic fluxes generated by the passage of current through said field controlling coil form closed magnetic circuits passing through said yoke of said rotor and said controlling magnetic poles and also passing through those stator poles aligned with said controlling magnetic poles in superposition with fluxes generated by said permanent magnets,

the polar arcuate angle θ

m of said permanent magnets and the polar arcuate angle θ

p of said controlling magnetic poles being set at values different from each other, with said polar arcuate angle θ

m of said permanent magnets being larger than said polar arcuate angle θ

p of said controlling magnetic poles.

2. A permanent magnet generator as set forth in claim 1, wherein:

the value θ

m/(θ

m+θ

p) has a lower limit of 0.55, said value θ

m/(θ

m+θ

p) being the polar arcuate angle θ

m of said permanent magnets divided by the sum θ

m+θ

p consisting of the polar arcuate angle θ

m of said permanent magnets plus the polar arcuate angle θ

p of said controlling magnetic poles.

3. A permanent magnet generator as set forth in claim 1, wherein:

the value θ

m/(θ

m+θ

p) has an upper limit of 0.7, said value θ

m/(θ

m+θ

p) being the polar arcuate angle θ

m of said permanent magnets divided by the sum θ

m+θ

p consisting of the polar arcuate angle θ

m of said permanent magnets plus the polar arcuate angle θ

p of said controlling magnetic poles.

4. A permanent magnet generator as set forth in claim 1, wherein:

the value θ

m/(θ

m+θ

p) has a lower limit at which the output exceeds by 20% the output of said generator during idle rotation when the polar arcuate angle θ

m of said permanent magnets and the polar arcuate angle θ

p of said controlling magnetic poles are equal to each other, said value θ

m/(θ

m+θ

p) being the polar arcuate angle θ

m of said permanent magnets divided by the sum θ

m+θ

p consisting of the polar arcuate angle θ

m of said permanent magnets plus the polar arcuate angle θ

p of said controlling magnetic poles.

5. A permanent magnet generator as set forth in claim 4, wherein:

said rotor is adapted to be driven by a given engine having a rated speed, and

the value θ

m/(θ

m+θ

p) has an upper limit at which the output is equal to the output of said generator which is obtained when said rotor is driven by said engine at said rated speed and when said value θ

m/(θ

m+θ

p) is set at said lower limit.

6. A permanent magnet generator as set forth in claim 1, wherein:

the value θ

m/(θ

m+θ

p)is set at 0.55≦

θ

m/(θ

m+θ

p)≦

0.7, said value θ

m/(θ

m+θ

p) being the polar arcuate angle θ

m of said permanent magnets divided by the sum θ

m+θ

p consisting of the polar arcuate angle θ

m of said permanent magnets plus the polar arcuate angle θ

p of said controlling magnetic poles.