Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-10
2002-03-19
Ro, Bentsu (Department: 2837)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S064000, C310S112000, C361S697000
Reexamination Certificate
active
06359352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicular AC generator having a pair of Y-connection circuits.
2. Description of the Related Art
For a conventional vehicular three-phase generator as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-218873 shown in
FIG. 15
, neutral-point diodes
23
N and
25
N configuring a neutral-point-current rectifying circuit are connected between a high-potential output side of a rectifier device
12
and a neutral point N of a stator coil
16
and between a low-potential output side of the rectifier device
12
and the neutral point N of the stator coil
16
and a three-phase voltage output of the stator coil
16
configured by a three-phase armature in which three windings Y are connected in a Y form is applied to rectifying diodes
23
and
25
of the rectifier device
12
for full-wave-rectifying the three phase voltage.
A vehicular three-phase generator has excellent characteristics in that output can be increased without increasing the size of the generator by providing the neutral-point-current rectifying circuit
12
having the neutral-point diodes
23
N and
25
N.
Specifically, the neutral-point diodes
23
N and
25
N are added to the rectifier device
12
, so that an exciting current circulating through each winding Y and the rectifier device
12
is derived from the neutral point N of the stator coil
16
so as to be supplied to the stator coil
16
and the rectifier device
12
, thereby improving the output of the generator. This type of vehicular three-phase generator is widely used at present.
The configuration of a conventional vehicular three-phase generator will be described below with reference to the accompanying drawings.
FIG. 13
is a sectional side view of the conventional vehicular three-phase generator (hereafter referred to as an AC generator) and
FIG. 14
is an internal view showing the interior of a rear bracket
2
shown in FIG.
13
.
The AC generator includes a case
3
formed of an aluminum front bracket
1
and a rear bracket
2
, a shaft
6
provided in the case
3
and having a pulley
4
fixed at one end thereof, a Landolt-type rotor
7
secured to the shaft
6
, a fan
5
secured to the opposite side surfaces of the rotor
7
, a stator
8
secured to an inner wall surface of the case
3
, a slip ring
9
for supplying current to a rotor coil
13
fixed to the other end of the shaft
6
, a pair of brushes
10
slidable on the slip ring
9
, a brush holder
11
receiving therein the brushes
10
, a rectifier device
12
electrically connected to a stator coil
16
for rectifying an AC voltage generated in the stator coil
16
into a DC voltage, a heat sink
19
fitted to the brush holder
11
, and a regulator
20
connected to the heat sink
19
for adjusting the field current to be supplied to the stator coil
16
in accordance with the output of the generator.
The rotor
7
comprises the rotor coil
13
for generating a magnetic flux and a pole core
14
covering the rotor coil
13
and on which magnetic poles are formed by the magnetic flux. The pole core
14
is comprised of a pair of a first pole-core body
21
and a second pole-core body
22
engaged with each other. The first pole-core body
21
and the second pole-core body
22
are made of iron and are respectively provided with a plurality of pawl-shaped magnetic poles
21
a
and
22
a.
The stator
8
comprises a stator core
15
and a stator coil
16
in the form of a conductor made of copper and wound on the stator core
15
. An AC voltage is generated due to the changing magnetic flux supplied from the rotor coil
13
in accordance with the rotation of the rotor
7
. As shown in
FIG. 14
, a plurality of slots
17
are provided on the stator core
15
in the radial direction thereof with their open portions facing the axis of rotation, and the stator coil
16
is wound in each slot
17
.
The rotor coil
13
, stator coil
16
, rectifier device
12
and regulator
20
normally generate heat while the generator generates power. A generator having a class 100A rated output current shows a calorific value of 60, 500, 120 or 6 W in the respective portions
13
,
16
,
12
and
20
at a relatively high-temperature rotation point.
To cool the heat produced by power generation, intake ports are provided in the front bracket
1
and the rear bracket
2
, respectively, for taking in cooling air from the outside with the fan
5
set on the shaft
6
. The cooling air taken in through the intake port of the rear bracket
2
passes through the rear-bracket-side heat sinks
24
,
24
of the rectifier device
12
and a vent hole formed facing the regulator heat sink
19
to cool the rectifier device
12
and the regulator
20
.
The cooling air cools the rectifier device
12
and the regulator
20
while passing through them, and is then directed in the centrifugal direction by the rear-bracket-side fan
5
to cool the rear-bracket-side stator coil end so as to be discharged to the outside through a bracket exhaust port.
Moreover, the cooling air drawn in the axial direction from the front-bracket-side intake port is directed in the centrifugal direction by the fan
5
to cool the front-bracket-side stator coil end and then discharged to the outside through a bracket exhaust port similar to the case of the rear bracket
2
side.
As shown in
FIG. 14
, the rectifier device
12
comprises the positive-pole-side heat sink
24
for supporting a plurality of positive-pole-side diodes
23
and a neutral-point diode
23
N, a negative-pole-side heat sink
26
for supporting a plurality of negative-pole-side diodes
25
and a neutral-point diode
25
N, and a circuit board
27
for electrically connecting anodes of the diodes
23
and
23
N, cathodes of the diodes
25
and
25
N, and the stator coil
16
. A three-phase voltage generated in the stator coil
16
is full-wave-rectified by the rectifier device
12
having the diodes
23
and
25
.
As shown in
FIGS. 16
to
18
, the rectifier device
12
including a heat sink and the like is configured so that the entirety thereof forms an approximate horseshoe shape. This configuration is used to store components by efficiently using the space in the generator because the shape of the generator is roughly cylindrical. As shown in
FIGS. 16 and 17
, the heat sinks
24
and
26
are made of aluminum or the like so as to radiate the heat produced by the diodes
23
,
25
,
23
N, and
25
N.
The heat sink
24
has a plurality of fins F protruding toward the rotor axis from the back of a joint surface between the positive-pole-side diodes
23
and
23
N. Moreover, the heat sink
26
for joining the negative-pole-side diodes
25
and
25
N is directly connected at its back side to the rear bracket
2
as a ground.
The diodes
23
,
25
,
23
N, and
25
N are molded, roughly rectangular and connected to the circuit board
27
by lead terminals protruding from one side of the diodes. The diodes
23
,
25
,
23
N, and
25
N are arranged on the heat sinks
24
and
26
in the radial direction so that they do not interfere with each other.
Among the diodes
23
,
25
,
23
N, and
25
N, the neutral-point diodes
23
N and
25
N are arranged so as to face a connector C for transferring a signal to and from the regulator
20
through the open portion of the slip ring.
Recently, in response to requests for increasing the output of AC generators due to the increased electric loads of vehicles, the output of generators has thus far been improved by adding a neutral-point diode to a full-wave rectifying circuit so as to derive an exciting current for circulating through windings and a full-wave rectifier device from the neutral point of a three-phase armature winding, and by using the exciting current with the three-phase armature winding and the full-wave rectifier device.
However, when a neutral-point diode is added to a full-wave rectifying circuit, a ripple current is output from the neutral-point diode and a ripple voltage is superimposed on a rectified output voltage and
Mitsubishi Denki & Kabushiki Kaisha
Ro Bentsu
Sughrue & Mion, PLLC
LandOfFree
Vehicular AC generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicular AC generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicular AC generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2823487