Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-09-07
2001-06-12
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S049540, C310S216006, C310S254100, C029S596000
Reexamination Certificate
active
06246142
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stator core for an AC generator to be mounted on a vehicle and a production process therefor.
2. Description of the Prior Art
FIG. 7
is a sectional view of a car AC generator of the prior art. This AC generator comprises a case
3
formed by connecting an aluminum front bracket
1
and an aluminum rear bracket
2
by a bolt
3
B, a shaft
5
provided in the case
3
and fitted with a pulley
4
for receiving the torque of an engine transmitted from a belt at one end, a random type rotor
6
fixed to the shaft
5
, fans
6
F fixed to both sides of the rotor
6
, a stator
7
A fixed on the inner wall of the case
3
, slip rings
8
, fixed to the other end of the shaft
5
, for supplying a current to the rotor
6
, a pair of brushes
9
and
9
which slide in contact with the slip rings
8
, a brush holder
10
for storing the brushes
9
and
9
, a rectifier
11
, electrically connected to the stator
7
A, for rectifying an AC generated in the stator
7
A into a DC, a heat sink
12
attached to the brush holder
10
, and a regulator
13
, attached to the heat sink
12
, for regulating an AC voltage generated in the stator
7
A. Denoted by
14
a
and
14
b
are bearings, and
15
brackets for connecting the AC generator to the engine.
The above rotor
6
comprises a rotor coil
6
A for generating a magnetic flux with a current supplied and a pole core
6
B for covering the rotor coil
6
A and forming a magnetic pole with the magnetic flux. The pole core
6
B consists of a pair of pole core unit
6
x
and a pole core unit
6
y
which engage with each other. The pole core units
6
x
and
6
y
are made from iron and have claw-like magnetic poles
62
and
62
, respectively.
The stator
7
A comprises a stator core
17
A and a stator coil
17
B formed of a conductor wound round the stator core
17
A. An AC is generated in the stator coil
17
B by the rotation of the rotor
6
according to changes in the magnetic flux from the rotor coil
6
A.
In the car AC generator constituted above, a current is supplied to the rotor coil
6
A from a battery (unshown) through the brushes
9
and
9
and the slip rings
8
to generate a magnetic flux. Meanwhile, the pulley
4
is driven by the engine and the rotor
6
is turned by the shaft
5
, thereby giving a rotating field to the stator coil
17
B to generate electromotive force in the stator coil
17
B. This AC electromotive force is rectified into a DC by the diodes
16
and
16
of the rectifier
11
, the DC is regulated by the regulator
13
, and the regulated DC is charged into the battery.
FIG. 8
is a sectional view of a car brushless AC generator of the prior art. The same or corresponding elements as those of
FIG. 7
are given the same reference symbols and their descriptions are omitted. In the case of this car brushless AC generator, when the engine is started, an excitation current is supplied from the battery to an excitation coil incorporated in an excitation core
19
through a regulator
13
A and the pole core units
6
x
and
6
y
of the rotor
6
are turned by the rotation of the shaft
5
, whereby electromotive force is generated in the stator coil
17
B of the stator
7
A. This AC electromotive force is rectified into a DC by the diodes
16
and
16
of the rectifier
11
, the DC is regulated by the regulator
13
A, and the regulated DC is charged into the battery.
FIG. 9
is a schematic perspective view showing an example of stator core
17
A used in the car AC generator of the prior art shown in FIG.
7
and FIG.
8
. The stator core
17
A having a predetermined thickness S in a lamination direction is constructed by winding a single long iron metal sheet
17
a
which is punched as shown in
FIG. 10
spirally in such a manner that the metal sheet layer are placed one upon another to form a cylinder and welding the cylinder at several locations on the peripheral side of the cylinder in the lamination direction. The metal sheet
17
a
has recesses
17
b
for forming slots
20
and recesses
17
c
for forming bolt shelter grooves
21
after lamination.
FIG. 11
is a schematic plan view of the stator core
17
A.
In
FIG. 9
, four welding spots are provided on the peripheral side at intervals of about 90° on the basis of the center of the cylinder. Generally speaking, four welding spots are provided from the view point of the strength of the core assembly. Welding is carried out linearly from the upper end to the lower end of the peripheral side of the cylinder with a jig movable in the lamination direction of the cylinder after the cylinder is sandwiched between chucks to bring the layers of the metal sheet
17
a
into close contact with one another.
A first-phase coil, a second-phase coil and a third-phase coil are inserted into the respective slots
20
of the stator core
17
A shown in
FIG. 9
to construct the stator
7
A shown in
FIG. 12
for inducing a three-phase AC. The coil of each phase is inserted into every three slots. Conductors
17
e forming the coil are fixed in each slot
20
with varnish
22
as shown in FIG.
13
and the opening side of the slot
20
is sealed with a resin
23
.
By winding the long metal sheet
17
a
punched as shown in
FIG. 10
spirally in such a matter that the metal sheet layers are placed one upon another, a plurality of bolt shelter grooves
21
are formed linearly on the peripheral side of the stator core
17
A so that they are continuous in a vertical direction and parallel to the lamination direction of the metal sheet
17
a
. The bolt shelter grooves
21
are formed at intervals of 10°, for example, on the basis of the center of the stator core
17
A.
Besides the above method, the stator core having a predetermined thickness may be constructed by placing a plurality of ring-shaped metal sheets one upon another to form a cylinder and welding the peripheral side of the cylinder at several locations in the same manner as described above.
SUMMARY OF THE INVENTION
According to the above-described stator core
17
A of the prior art, the peripheral side of the cylinder is welded linearly (parallel to the above bolt shelter grooves
21
) in the lamination direction of the metal sheet continuously from the upper end to the lower end of the cylinder. Therefore, when suction force between the rotor
6
and the stator
7
A is applied to the stator core
17
A, there arises such a problem that the stator
7
A generates a vibration mode in a radial direction as a whole with a linear welded portion serving as a joint as shown in FIG.
14
.
Japanese Utility Patent Application No. 53-141410 discloses a stator core
30
in which a non-welded portion
31
is partly formed as shown in FIG.
15
. Welded portions which are continuous in a vertical direction are formed at several welding spots on the peripheral side of the stator core
30
having a predetermined thickness S. However, in this stator core
30
, welded portions
32
continuous in a vertical direction are concentratedly formed at each welding spot and it cannot be said that the welded portions
32
are scattered in the peripheral direction and vertical direction of the stator core. Therefore, the welded portions
32
serve as joints and a vibration mode is still generated with some joints because the joints do not disappear and a variety of elements are existent in a car generator having a wide range of revolution speed.
As shown in
FIG. 16
, Japanese Laid-open Patent Application No. 54-124845 discloses a stator core
40
which is produced by forming oblique welded portions
41
on the peripheral side in a zigzag manner. Even in this case, since the upper and lower ends of the welded portion
41
are close to each other, the rigidities of the upper and lower ends of the welded portion
41
are high and joints cannot be eliminated completely. Therefore, a vibration mode is still generated.
It is an object of the present invention to solve the above problem of the prior art to provide a stator core which hardly generates joint vibration in a radial dir
Adachi Katsumi
Asao Yoshihito
Higashino Kyoko
Kashihara Toshiaki
Ohashi Atsushi
Mitsubishi Denki & Kabushiki Kaisha
Mullins Burton
Sughrue Mion Zinn Macpeak & Seas, PLLC
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