Car AC generator with a slip ring support and a slinger unit...

Details Car AC generator with a slip ring support and a slinger unit... Car AC generator with a slip ring support and a slinger unit...

1999-05-03

2001-07-10

Tamai, Karl (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S239000

Reexamination Certificate

active

06259182

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a car AC generator and, particularly, to a water-proof structure for slip rings and brushes.
2. Description of the Prior Art
FIG. 8
is a sectional view of a car AC generator equipped with a vacuum pump of the prior art,
FIG. 9
is an enlarged sectional view of slip rings
13
, brushes
17
and parts therearound shown in
FIG. 8
, and
FIG. 10
is a sectional view cut on line A—A of FIG.
9
. In
FIG. 8
, reference numeral
1
denotes a bracket front and
2
a bracket rear both of which are arranged to face each other to form the outer shell of the generator. Denoted by
3
is a cylindrical stator which consists of a core and a coil and is fastened to the peripheral wall of the bracket front
1
and the peripheral wall of the bracket rear
2
by a bolt
40
in the inside space surrounded by the bracket front
1
and the bracket rear
2
of the outer shell of the generator. Denoted by
4
is a generator shaft which is installed in the center portions of the bracket front
1
and the bracket rear
2
in such a manner that it can rotate by a bearing front
5
and a bearing rear
6
. Reference numeral
7
denotes a pulley which is fastened to the generator shaft
4
projecting forward from the bracket front
1
by a nut
8
in such a manner that it can rotate together with the generator shaft
4
. Denoted by
9
is a cylindrical rotor which consists of a set of a magnetic pole and a field coil and is fitted in the stator
3
in such a manner that it can rotate together with the generator shaft
4
. Denoted by
10
is a fan front which is fixed to the front side of the magnetic pole of the rotor
9
and
11
a fan rear which is fixed to the rear side of the magnetic pole of the rotor
9
. Denoted by
12
is a cylindrical slip ring support unit made from a synthetic resin and fixed to the generator shaft
4
between the rotor
9
and the bearing rear
6
in such a manner that it can rotate together with the generator shaft
4
. Denoted by
13
is a plurality of annular slip rings which are spaced apart from one another in a direction parallel to the axial direction of the generator shaft
4
and fixed to the outer peripheral surface of the slip ring support unit
12
. Denoted by
14
is a packing and
15
a cylindrical slinger unit made from a synthetic resin and fixed to the center portion of the bracket rear
2
through the packing
14
in such a manner that it surrounds the slip ring support unit. Denoted by
16
is a brush holder unit projecting outward from part of the slinger unit
15
and
17
a plurality of brushes which correspond to the number of the slip rings
13
and are inserted into the brush holder unit
16
and whose end portions projecting into the inside of the slinger unit
15
from the brush holder unit
16
are each in contact with the slip rings
13
. Denoted by
18
is a brush spring for pressing the plurality of brushes
17
against the slip rings
13
elastically,
42
a regulator which is fixed to the brush holder unit
16
,
19
a rectifier which is composed of diodes and the like and fixed to the peripheral wall of the bracket rear
2
outside the slinger unit
15
. Denoted by
20
is a slip ring terminal lead wire which projects outward from the slip ring support unit
12
,
21
a coil lead wire extending from the field coil of the rotor
9
and connected to the slip ring terminal lead wire
20
,
22
is a vacuum pump which is installed outside the bracket rear
2
, and
23
a vacuum pump rotor which is mated with the spline unit
24
of the generator shaft
4
projecting backward from the bracket rear
2
in such a manner that it can rotate together with the spline unit
24
.
A description is subsequently given of the operation of the car AC generator equipped with a vacuum pump when it is mounted on an automobile. When a driver turns on the ignition switch of the automobile while the AC generator equipped with a vacuum pump is installed outside the cylinder block of an engine and a ring-shaped belt is stretched between a pulley provided on the crank shaft of the engine and the pulley
7
of the car AC generator equipped with a vacuum pump, a current runs through an ignition coil from the battery of the automobile to start the engine and an excitation current runs from the battery to the field coil of the rotor
9
through the regulator
42
, the brushes
17
and the slip rings
13
. In this state, when the generator shaft
4
turns by the start of the engine and the rotor
9
rotates, 3-phase AC induced electromotive force is generated in the coil of the stator
3
, rectified by the rectifier
19
and charged into the battery. By the rotation of the rotor
9
, the fan front
10
and the fan rear
11
are rotated and air in the engine room of the automobile is supplied into the inside space of the outer shell of the generator from the inlet port of the bracket front
1
and the inlet port of the bracket rear
2
to cool such parts as the stator
3
, the rotor
9
, the regulator
42
and the rectifier
19
in the inside space of the outer shell of the generator and is exhausted into the engine room from the outlet port of the bracket front
1
and the outlet port of the bracket rear
2
.
In the car AC generator equipped with a vacuum pump of the prior art, as shown in
FIG. 9
, the space between the bracket rear
2
and the slinger unit
15
is made waterproof by the packing
14
. However, since the slinger unit
15
is fixed to the bracket rear
2
and the slip rings
13
turn together with the generator shaft
4
, a gap
25
is formed between the slinger unit
15
and the slip ring support unit
12
. When water enters the inside space of the outer shell of the generator from the inlet ports, outlet ports and the like of the bracket front
1
and the bracket rear
2
, there is a possibility that the water enters the gap
25
from an opening
26
located on the front side (pulley side) of the slinger unit
15
. Therefore, a water-proof structure is desired for preventing water entering the gap
25
from the opening
26
from reaching contact portions between the slip rings
13
and the brushes
17
. However, a labyrinth
27
defined by the inner peripheral surface of the slinger unit
15
and the outer peripheral surface of the slip ring support unit
12
has a shape disadvantageous for waterproofing. That is, the inner peripheral surface of the slinger unit
15
is a surface parallel to the generator shaft
4
. The outer peripheral surface of the slip ring support unit
12
has an opening side surface
12
a
parallel to the inner peripheral surface of the slinger unit
15
and a slip ring side surface
12
b
which falls toward the generator shaft
4
from the opening side surface
12
a.
Therefore, since the generator shaft
4
turns during the operation of the generator, water entering from the opening
26
is scattered toward the slinger unit
15
from the opening side surface
12
a
of the slip ring support unit
12
by centrifugal force, and the scattered water flows down along the inner peripheral surface of the slinger unit
15
as shown by an arrow X
1
in
FIG. 10
, goes over a brush seat
28
which is provided inside the brush holder unit
16
to surround the brushes
17
from the inner peripheral surface of the slinger unit
15
and reaches the brushes
17
. Therefore, there is a possibility that water flows into the gap between the brushes
17
and the brush seat
28
.
Although the generator shaft
4
stops turning during the suspension of the generator, when water flows into the slip ring side surface
12
b
from the opening side surface
12
a
of the slip ring support unit
12
through the opening
26
by vibration transmitted to the AC generator equipped with a vacuum pump from the automobile, there is a possibility that the water flows down along the slip ring side surface
12
b
as shown by an arrow X
2
in FIG.
10
and runs into the contact portions between the slip rings
13
and the brushes
17
.
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