Magneto generator

Details Magneto generator Magneto generator

2004-02-03

2004-11-09

Mullins, Burton (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S058000, C310S061000, C310S156260, C310S266000

Reexamination Certificate

active

06815849

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to an outer rotor type magneto generator including a magnet rotor comprised by mounting a permanent magnet to an inner periphery of a peripheral wall of a substantially cup-shaped rotor yoke, and an armature placed inside the magnet rotor.
BACKGROUND OF THE INVENTION
An outer rotor type magneto generator includes, as shown in
FIGS. 6A and 6B
, a magnet rotor
3
having a rotor yoke
1
formed to become a substantial cup shape having a peripheral wall
1
a
and a bottom wall
1
b
, and a permanent magnet
2
mounted to an inner periphery of the peripheral wall
1
a
of the rotor yoke
1
, and an armature
4
placed inside the magnet rotor
3
.
The rotor yoke
1
has a boss
1
c
at the center of the bottom wall
1
b
, and the boss is mounted to a rotation axis of an unshown prime mover (in many cases, an internal combustion engine).
The armature
4
includes an armature core
5
and an armature coil
6
wound around the armature core, and is secured to a casing or the like of the prime mover, so that a magnetic pole portion provided on an outer peripheral portion of the armature core
5
faces the magnet
2
of the magnet rotor
3
with a predetermined gap therebetween. A generator shown in
FIGS. 6A
to
6
C is disclosed in Japanese Patent Publication No.6-91718.
In such a generator, the armature coil
6
is heated by the loss produced when a load current passes through the armature coil
6
, and in order to produce large output from the generator, efficient cooling of the armature coil is required.
Japanese Patent Publication No. 6-91718 proposes a cooling structure where a bottom wall
1
b
of a rotor yoke
1
is drilled to form a plurality of air vents
1
d
,
1
d
, . . . along an outer peripheral portion of the bottom wall
1
b
, and a cooling air introducing portion
9
′ corresponding to each air vent
1
d
is provided in an annular plate
8
secured by screws
7
to an outer surface of the bottom wall
1
b
of the rotor yoke
1
, thereby introducing cooling air into each air vent
1
d
through a cooling air introducing passage
10
′ inside the cooling air introducing portion
9
′.
As shown in
FIG. 6C
, the cooling air introducing portion
9
′ is formed to protrude in an opposite direction to the bottom wall
1
b
and cover at least a part of a corresponding air vent
1
d
, and the cooling air introducing passage
10
′ having a semicircular section is formed inside the cooling air introducing portion
9
′. The cooling air introducing passage
10
′ is provided to open forward in the rotational direction of the rotor yoke
1
(in the direction of the arrow in FIG.
6
A).
In the magneto generator disclosed in Japanese Patent Publication No. 6-91718, as shown in
FIG. 6A
, the cooling air introducing portion
9
′ is provided so that the cooling air introducing passage
10
′ opens tangentially of the outer peripheral portion of the rotor yoke. This, combined with the semicircular section of the cooling air introducing passage
10
′, prevents increase in sectional area of an opening of the cooling air introducing passage
10
′. Thus, the amount of cooling air blown on the armature
4
through the air vent
1
d
is limited, which prevents enhancement of the cooling effect of the armature.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a magneto generator capable of blowing cooling air larger in amount than a conventional magneto generator on an armature through an air vent provided in a bottom wall of a rotor yoke to enhance the cooling effect of the armature.
The invention is directed to a magneto generator including: a magnet rotor having a cup-shaped rotor yoke with a peripheral wall and a bottom wall, and a permanent magnet mounted to an inner periphery of the peripheral wall of the rotor yoke; and an armature placed inside the magnet rotor.
In the invention, the bottom wall of the rotor yoke is drilled at a portion closer to an outer periphery to circumferentially provide a plurality of air vents in the peripheral wall of the rotor yoke, and a hollow cooling air introducing portion is provided for each of the plurality of air vents.
Each cooling air introducing portion is provided to protrude in an opposite direction to an opening in the peripheral wall of the rotor yoke and cover at least a part of a corresponding air vent, and a cooling air introducing passage is formed inside the cooling air introducing portion.
An end of the cooling air introducing passage inside the cooling air introducing portion communicates with the inside of the rotor yoke through a corresponding air vent, while the other end of the cooling air introducing passage inside the cooling air introducing portion opens forward in the rotational direction of the magnet rotor through an opening end provided in the cooling air introducing portion.
The cooling air introducing portion has an outer side wall provided to extend in a sloping direction from near a corresponding air vent toward an outer peripheral portion of the rotor yoke and reach the opening end of the cooling air introducing portion.
The opening end of the cooling air introducing portion is directed in a sloping direction toward an inner diameter of the rotor yoke with respect to the direction orthogonal to a reference plane including both a straight line between the center of the bottom wall of the rotor yoke and the center of a corresponding air vent, and a central axis of the rotor yoke.
As described above, the outer side wall of the cooling air introducing portion is provided to extend in the sloping direction from near the corresponding air vent toward the outer peripheral portion of the rotor yoke and reach the opening end of the cooling air introducing portion, and the opening end of the cooling air introducing portion is directed in the sloping direction with respect to the direction orthogonal to the reference plane. This allows a sectional area of the cooling air introducing passage at the opening end of the cooling air introducing portion to be larger than a sectional area of the cooling air introducing passage inside a portion along the reference plane of the cooling air introducing portion.
Therefore, according to the invention, the cooling air introducing passage has a larger opening area than a conventional magneto generator having the opening end of the cooling air introducing portion opening tangentially of the rotor yoke, and thus a larger amount of cooling air can be introduced into the cooling air introducing portion with rotation of the rotor to enhance the cooling effect of the armature as compared with the conventional magneto generator of this type.


REFERENCES:
patent: 4797602 (1989-01-01), West
patent: 5217353 (1993-06-01), De Filippis
patent: 6107714 (2000-08-01), Fischer
patent: 6384494 (2002-05-01), Avidano et al.
patent: 6744157 (2004-06-01), Choi et al.
patent: 3329720 (1984-02-01), None
patent: 3038781 (1977-04-01), None
patent: 59035548 (1984-02-01), None
patent: 04038149 (1992-02-01), None
patent: 6-91718 (1994-11-01), None
patent: 2000217321 (2000-08-01), None
patent: 2002136080 (2004-05-01), None

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