Vehicle alternator

Details Vehicle alternator Vehicle alternator

2000-08-14

2002-07-09

Nguyen, Tran (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S254100

Reexamination Certificate

active

06417594

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a vehicle alternator, and more specifically to a stator structure thereof.
FIG. 9
is a side cross-sectional view of a conventional alternator, and
FIG. 10
is a perspective view illustrating a rotor portion thereof.
This alternator comprises a case
33
composed of a front bracket
31
and a rear bracket
32
which are made of aluminum, a shaft
35
provided within a case
33
and having a pulley
34
secured at one end, a rotor
36
of lundell type secured to this shaft
35
, fans
37
secured to both side faces of this rotor
36
, a stator
38
fixed to an inner wall face within this case
33
, a slip ring
39
fixed to the other end portion of the shaft
35
for supplying an electric current to the rotor
36
, a pair of brushes
40
for scrubbing this slip ring
39
, a brush holder
41
containing these brushes
40
, a commutator
60
electrically connected to the stator
38
for rectifying the alternating current produced in the stator
38
to direct current, a heat sink
42
fitted into the brush holder
41
, and a regulator
43
attached to this heat sink
42
for regulating the magnitude of alternating voltage produced in the stator
38
.
The stator
38
comprises a stator core
44
, and a stator coil
45
for generating an alternating current by changes of the magnetic flux from a rotor coil, as described below, along with the rotation of the rotor
36
, with a conducting wire wound around this stator core
44
.
The rotor
36
comprises a rotor coil
46
for producing the magnetic flux by passing the electric current, and a pole core
47
, provided over this rotor coil
46
, having the magnetic pole formed by the magnetic flux.
The pole core
47
is composed of a first pole core body
48
and a pole core body
49
which are paired and mated alternately. The first pole core body
48
and the pole core body
49
are constituted integrally of a plurality of claw-like magnetic pole pieces
50
,
51
having a pawl shape which are disposed evenly around the peripheral portion thereof and project in one direction, with a thick disk-like bottom portion made of iron as a base. Adjacent claw-like magnetic pole pieces
50
,
51
are disposed with a certain magnetic pole spacing H to prevent the magnetic flux from leaking between both pieces.
Since the conventional vehicle alternator is constituted as above, in a claw pole rotor-type alternator, a magnetic flux which passes from the rotor to the stator and is referred to as a leakage flux is routed over the inner peripheral surface of stator iron core along the axial direction into the opposite pole of the rotor. This is caused by virtue of the structure of claw pole, decreasing the magnetic flux that is effective for the generation of power, and lowering the output. Since it produces the pulsation of magnetic flux, it will fluctuate the generated voltage and disorder the output waveform, causing the ripple of generated voltage in the vehicle alternator, and the electromagnetic noise to occur to have a detrimental effect on the external apparatus.
The pulsation of magnetic flux over the inner peripheral surface of stator iron core might increase the fluctuation of magnetic exciting force at an air gap portion, deteriorating the electromagnetic sound which is produced due to resonance of the stator.
It should be noted that in the conventional example for decreasing the leakage flux as above described, there is an art of having two slots for every pole and every phase as disclosed in the Unexamined Japanese Patent Application Publication No. Hei 4-26345 publication, but it was difficult to perform the winding because of the multiple slots.
SUMMARY OF THE INVENTION
This invention has been achieved to resolve the above-mentioned problems, and an object of the invention is to provide a vehicle alternator which can provide the greater output, less ripple and less electromagnetic sound by reducing the leakage flux without providing multiple slots.
A vehicle alternator according to aspect
1
of this invention comprises a rotor provided within a case and having claw-like magnetic pole pieces, a stator fixed within the case, and a commutator electrically connected to the stator, wherein the magnetic reluctance of the axial central part of teeth in the stator is increased.
A vehicle alternator according to aspect
2
comprises a rotor provided within a case and having claw-like magnetic pole pieces, a stator fixed within the case, and a commutator electrically connected to the stator, wherein the magnetic flux passing cross section of the axial central part of teeth in the stator is decreased.
A vehicle alternator according to aspect
3
comprises a rotor provided within a case and having claw-like magnetic pole pieces, a stator fixed within the case, and a commutator electrically connected to the stator, wherein a concave portion is provided at the tip of the axial central part of teeth in the stator.
A vehicle alternator according to aspect
4
comprises a rotor provided within a case and having claw-like magnetic pole pieces, a stator fixed within the case, and a commutator electrically connected to the stator, wherein a recess portion is provided in the axial central part of teeth in the stator and on either forward or backward face in the rotational direction of the rotor.
A vehicle alternator according to aspect
5
comprises a rotor provided within a case and having claw-like magnetic pole pieces, a stator fixed within the case, and a commutator electrically connected to the stator, wherein a nonmagnetic material is provided in the axial central part of teeth in the stator.


REFERENCES:
patent: 5936325 (1999-08-01), Permuy
patent: 6023119 (2000-02-01), Asao
patent: 6034464 (2000-03-01), Asao
patent: 4-26345 (1985-05-01), None
patent: 60-87639 (1985-05-01), None
patent: 411299131 (1999-10-01), None

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