Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-12-13
2001-09-04
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S080200, C165S080300, C165S185000, C174S016300, C257S713000, C361S705000, C361S707000, C363S145000
Reexamination Certificate
active
06285552
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rectifier for an alternating current generator for a vehicle and particularly relates to an arrangement of heat sink for supporting diodes of the rectifier.
2. Description of the Prior Art
FIG. 4
is sectional view showing a conventional alternating current generator for a vehicle and the alternating current generator consists of a case consisting of a front bracket
1
and a rear bracket
2
made of aluminum, a shaft
6
being disposed in the case
3
and having a pulley
4
being fixed at an end of the shaft
6
, a rundle type rotor
7
secured to the shaft
6
, fans
5
fixed at both side surfaces of the rotor
7
, a stator
8
fixed to an inner wall within the case
3
, slip rings
9
being fixed to another end of the shaft
6
and for supplying electricity to the rotor
7
, a pair of brushes which slide on the slip rings
9
, brush holders
11
for storing the brushes
10
, a rectifier
12
being electrically connected to the stator
8
and for rectifying the alternating current generated through the stator to a direct current, a heat sink
17
fit to the brush holder
11
, and a regulator being bonded to the heat sink
17
and for regulating the magnitude of the alternating current voltage generated through the stator.
The rotor
7
consists of a rotor coil
13
for producing a magnetic flux by supplying electric current therethrough and a pole core
14
being arranged to cover the coil
13
and for producing magnetic poles due to the magnetic flux passing through the core
14
. The pole core consisting of mutually mated first core
21
and second core
22
, and those cores
21
and
22
are made of iron and have claw shaped magnetic poles
23
and
24
respectively.
The stator
8
has a stator core
15
and stator coils
16
wound around the stator core
15
. The stator
8
generates the alternating current through the stator coils
16
due to the variation of the magnetic flux from the rotor coil
13
produced as a result of rotation of the rotor
7
.
As shown by
FIG. 5
, the rectifier
12
consists of heat sinks
25
for supporting a plurality of diodes
26
on the plus side and heat sinks
27
for supporting a plurality of diodes
28
on the minus side. The plus side heat sink
25
has fins
25
a
. The plus side heat sink
25
and fins
25
a
are formed to be a single body, and the minus side heat sink
27
shares function of earth and is directly connected to the rear bracket
2
.
The heat sinks
25
,
27
are formed to be horseshoe shaped from the material such as ADC10 and ADC12 by means of aluminum die-casting.
On account of space efficiency, those diodes
26
and
28
are secured by means such as soldering on the heat sinks
25
,
27
with an optimum positioning securing a good thermal conduction.
Also another arrangement can be seen such that diodes are fixed and supported so that their longitudinal directions come out to be in parallel with respective axes of the heat sinks and the fins of the heat sinks of both sides of plus and minus are placed being perpendicular to that axes.
In the alterating current generator mentioned as above, the magnetix flux is produced by supplying electric current through the rotor coil
13
through the slip rings
9
, and by this magnetic flux, the claw shaped magnetic pole
23
of the first core body
21
is magnetized to N pole and the claw shaped magnetic pole
24
of the second magnetic body is magnetized to S pole.
On the other hand, because the pulley
4
is driven by the engine and the rotor
7
is rotated by the shaft
6
, a rotating magnetic filed is applied to the stator coil
16
resulting in a generation of an electromagnetic force corresponding to the variation of the magnetic field. This electromotive force is rectified by the rectifier
12
to a direct current and its magnitude is regulated by the regulator
18
and the electricity is charged to unshown battery.
The cooling air stream produced by the fan
5
rotated by the shaft
6
are taken into the interior of the case
3
from the air intake port
1
a
,
2
a
of the front bracket
1
and the rear bracket
2
, respectively and on the rear side the air stream passes through heat generating members such as the rectifier
12
and regulator
18
and cools those heat generating members and also passes through the fan
5
from its inner radius side to its outer radius side and cools front end and rear end of the stator coil
16
and is exhausted from the exhaust port
1
b
and
2
b
of the front bracket
1
and the rear bracket
2
, respectively.
Heat sinks
25
and
17
of the rectifier
12
and the regulator
18
those of which have high degree of heat generation and affect output performance due to high temperature, in order to promote heat dissipation, are provided with fins
25
a
and
17
a
, respectively and are adapted to introduce cooling air stream thereinto.
Among the heat sinks of the rectifier
12
, the minus side heat sink
27
has no fins but the air intake port
2
a
on the side of grownded rear bracket
2
serves as fins of heat sink
27
mentioned as above, and thus the same cooling is performed.
Now in the conventional rectifier as mentioned above, in order to improve thermal conductivity, productivity and reliability, respective diodes were fixed to heat sinks by soldering after forming a metal coating layer (meshed portion in the drawings) having a good solderability such as Ni plating on to the surface of heat sink
27
,
25
of aluminum die-cast as shown by FIGS.
6
(
a
), (
b
). Though the portions to be coated which is actually necessary for soldering are limited merely to the recessed portion
25
b
,
27
a
for fixation of diodes, for consideration of reasons such as coating process the heat sink body being kept intact is diped into a coating solution bath and thus whole heat sinks
27
,
25
are obliged to be coated.
On the other hand, because of generation of high calorific value by diodes
26
,
28
due to a sustained continuous electric current during generations of electricity by the generator, as the number of diodes increases the cooling function is maintained by correspondingly enlarging the heat sinks for cooling. To perform heat dissipation correspondingly to the increased calorific value, total area of fins are arranged to be increased by diminishing pitch of the fins
25
a
and increasing the number of fins.
Accordingly, fin portion which is not required to be coated increases apace.
Thus as seen in the conventional heat sinks, when whole heat sinks
27
,
25
are coated, the area, which must be coated but is not necessary to be served for soldering, is further increased and thus there gives rise to a problem of raising up the surface treatment cost rapidly.
SUMMARY OF THE INVENTION
The present invention is made in order to solve forgoing problems and an object of the invention is to from merely a coating layer being necessary for soldering on to the heat sink of the rectifier of the alternating current generator for a vehicle.
In the rectifier of an alternating current as recited in claim
1
of the present invention, at least a portion of each of the heat sinks, to which a diode is soldered, is formed to be a member consisting of a metal having a good solderability other than aluminum or consisting of a metal having a good solderability being adhered on to a metal other than aluminum and said heat sinks are formed by insert die-cast with the members served as insert members.
In a rectifier of a alternating current generator as recited in claim
2
, the insert members are formed by adhesively coating a metal having a good solderability on to a hyper-eutectic aluminum having a melting point higher than that of aluminum die-cast of heat sink body.
REFERENCES:
patent: 4546409 (1985-10-01), Yoshino et al.
patent: 4701828 (1987-10-01), Weiner
patent: 5828564 (1998-10-01), Mori et al.
patent: 6-67194 (1994-08-01), None
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Thompson Gregory
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