Vehicular AC generator

Details Vehicular AC generator Vehicular AC generator

2000-05-11

2002-07-09

Tamai, Karl (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S089000, C310S256000

Reexamination Certificate

active

06417585

ABSTRACT:

TECHNICAL FIELD
This invention relates to a vehicular ac generator having a bracket having formed in a bracket main body an air intake port rib and an air exhaust port rib for defining a cooling air intake port and exhaust port.
BACKGROUND ART
FIG. 9
is a side sectional view of a conventional vehicular ac generator,
FIG. 10
is a front view of the front bracket shown in
FIG. 9
,
FIG. 11
is a front view of the rear bracket shown in FIG.
9
and
FIG. 12
is a perspective view of a rotor.
This ac generator comprises a case
3
composed of a front bracket
1
and a rear bracket
2
made of aluminum, a shaft
6
disposed within the case
3
and having secured to its one end portion a pulley
4
, a rotor
7
of the Rundle type fixed to the shaft
6
, a fan
5
secured to the opposite side of the rotor
7
, a stator
8
secured to the inner wall surface of the case
3
, a slip ring
9
secured to the other end portion of the shaft
6
for supplying an electric current to the rotor
7
, a pair of brushes
10
in a sliding-contact relationship with the slip ring
9
, a brush holder
11
housing the brushes
10
, a commutator
12
electrically connected to the stator
8
, a heat sink
16
mounted to the brush holder
11
and a regulator
17
bonded to the heat sink
16
and regulating the magnitude of the ac voltage generated at the stator
8
.
The rotor
7
comprises a rotor coil
13
through which an electric current is supplied to generate a magnetic flux and a pole core
14
positioned over the rotor coil
13
, where an magnetic poles are formed by the magnetic flux. The pole core
14
is composed of a pair of a first pole core member
18
and a second pole core member
19
meshing with each other. The first pole core member
18
and the second pole core member
19
comprises pawl-shaped magnetic poles made of iron and in the shape of a pawl. The neighboring pawl-shaped magnetic poles
20
and
21
are arranged with a predetermined gap is defined between the magnetic poles so that no flux leakage occurs between the pawl-shaped magnetic poles
20
and
21
and that a cooling air passage for cooling the rotor coil
13
is defined.
The stator
8
comprises a stator core
15
and a stator coil
81
which is an electrical conductor wound on the stator core
15
and in which an ac power is generated due to the change in the magnetic flux in the rotor coil
13
as the rotor
7
rotates.
The rectifier
12
comprises a diode
26
for rectifying the ac current generated in the stator
8
into a dc current and a heat sink
27
for dissipating the heat generated at the diode
26
.
As shown in
FIG. 10
, the front bracket
1
has disposed at an outer circumferential portion of the bracket main body
80
a plurality of exhaust ports
29
formed by a plurality of exhaust port ribs
28
. Inside of the exhaust port
29
, intake ports
34
are defined by a plurality of intake ribs
35
. Also, at the outer circumferential portion of the bracket main body
80
, through holes
30
are formed at four positions spaced by 90°. Bolts
31
are inserted into these through holes
30
and thread-engaged into the rear bracket
2
, whereby the rear bracket
2
together with the front bracket
1
holds the stator core
15
therebetween. Also, mounting holes
33
are provided at a pair of mounting leg portions
32
arranged in the V-shape. Bolts (not shown) are passed through the mounting holes
33
and thread-engaged with the engine main body (not shown), whereby the vehicular ac generator is secured to the engine main body.
Also as for the rear bracket
2
, as illustrated in
FIG. 11
, similarly to the front bracket
1
, the exhaust ports
29
are defined in the outer circumferential portion of the bracket main body
80
by the plurality of exhaust port ribs
28
and the intake ports
34
are defined in side of the exhaust ports
29
by the intake port ribs
35
. Also, mounting leg portions
32
having the mounting holes
33
corresponding to the front bracket
1
are provided.
According to the vehicular ac generator having the above structure, an electric current is supplied form a battery (not shown) to the rotor coil
13
through the brush
10
and the slip ring
9
to generate a magnetic flux, thereby magnetizing the pawl-shaped magnetic pole
20
of the first pawl core member
18
in the N-pole and the pawl-shaped magnetic pole
21
of the second pawl core member
19
into the S-pole. On the other hand, the pulley
4
is driven by the engine and the shaft
6
causes the rotation of the rotator
7
to rotate, so that a rotating field is applied to the stator coil
81
to generate an electromotive force in the stator coil
81
. This ac electromotive force is rectified into a dc current through the rectifier
12
and regulated in its magnitude by the regulator
17
to thereby charged in the battery.
The rotor coil
13
and the stator coil
81
always generate heat during the power generation. On the other hand, the fan
5
is rotating for dissipating the heat generated by the power generation.
That is, as shown in
FIG. 9
, the cooling air sucked in the axial direction through the intake ports
34
on the side of the front bracket
1
flows between the intake port ribs
35
deflected into the centrifugal direction by the fan
5
, cools the front side end positron of the stator coil
81
and is exhausted to the outside through the exhaust ports
29
between the exhaust port ribs
28
. Also, the cooling air sucked through the intake ports
29
defined between the exhaust port ribs
28
flows between the intake port rib
35
, flows through the heat sink
27
of the rectifier
12
and the heat sink
16
of the regulator
17
, deflected by the fan
5
in the A centrifugal direction, cools the rear side of the stator coil
81
and is exhausted to the outside through the exhaust ports
29
of the rear bracket
2
.
As for the fan
5
, the centrifugal fan
5
having a plurality of fan blades
55
is used as illustrated in
FIG. 12
, so that the air flow is deflected by the fan blades
55
at right angles and exhausted in the axial direction, generating pressure oscillation due to the conflicts between the fan blades
55
and the air at the flow incoming portion, giving an adverse effect in the wind noise. Also, an annular plate
56
fastened to connect the tips of the fan blades together is provided for the purpose of noise reduction.
It is to be noted that the intake ports ribs
29
, the exhaust port ribs
35
and the front and rear brackets
1
and
2
not only prevent the ingress of any foreign matter from outside, but also serves and cooling fins for dissipating the heat transmitted from the stator
8
to the front and the rear brackets
1
and
2
.
The exhaust port ribs
28
of the front and rear brackets
1
and
2
of this conventional design have not been tilted or inclined in the direction rotation of the rotor by an angle equal to or within 0° to 15° with respect to the radial line from the rotational axis. Also, the intake port ribs
35
of the front bracket
1
have not had any inclination with respect to the radiation line from the rotational axis. With such the structure, a air flow resistance relative to the direction of the absolute velocity of the cooling air discharged from the fan
5
of the rotor
7
is large and the flow rate has been limited, so that the cooling efficiency has been poor. Therefore, the temperature rise is increased and, as a result, the power output had to be limited. Also, as for the intake ports
34
, although the air flows with an inclination due to the whirling component of the incoming air generated by the rotation of the fan
5
, the intake port ribs
35
cause the air flow resistance to be large, resulting in the decrease in air flow amount.
Also, since the exhaust port ribs
28
and the intake port ribs
35
have not been in line with the direction of the absolute velocity of the cooling air discharged from the fan
5
, the interfering noise was increased.
This invention has been made in order to resolve the above-discussed problems and has as its object the provisio

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