Cooling structure of generator

Details Cooling structure of generator Cooling structure of generator

2002-08-06

2004-03-23

Dougherty, Thomas M. (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S054000, C310S058000, C310S06000A

Reexamination Certificate

active

06710479

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a generator having a high-speed rotor and a cooling structure that effectively cools the generator.
BACKGROUND ART
A generator will be explained below with reference to
FIG. 13
to FIG.
15
. An example of the generator that uses a compact gas turbine as a motor will be explained.
In the figures,
1
denotes a generator. This generator
1
comprises a casing
2
, a rotor
4
that is accommodated in the casing
2
and is rotatably supported by a bearing
3
in the casing
2
, and a stator
6
that is accommodated in the casing
2
and is disposed with a clearance
5
around the external surrounding of the rotor
4
.
The rotor
4
is structured by a permanent magnet such as samarium cobalt. The stator
6
is constructed of an iron core
7
having a lamination of a large number of steel sheets (for example, silicon steel sheets having a thickness of about 0.15 mm), and a coil
8
wound around the iron core
7
. At the center of the iron core
7
, there are provided a circular through hole
15
and a plurality of long grooves
16
in a radial shape to continue to the through hole
15
. In the through hole
15
, the rotor
4
is inserted with a slight clearance
5
. The coil
8
is disposed in the long grooves
16
.
In the casing
2
, there are provided a cooling oil entrance
9
, a cooling oil exit
10
, and a cooling oil passage
11
that is communicated to the cooling oil entrance
9
and the cooling oil exit
10
and that passes through the external periphery of the stator
6
. The cooling oil passage
11
is constructed of a branched radial portion that is communicated to the cooling oil entrance
9
, a ring portion that passes through the eternal periphery of the stator
6
, and a branched radial portion that is communicated to the cooling oil exit
10
. The casing
2
is provided with a lubricating oil entrance
12
, a lubricating oil exit
13
, and a lubricating oil passage
14
that is communicated to the lubricating oil entrance
12
and the lubricating oil exit
13
and that lubricates the bearing
3
.
In the figures,
17
denotes a compact gas turbine that is what is called a micro gas turbine. This compact gas turbine
17
comprises a rotary shaft
20
that is rotatably supported by high-speed bearings
19
in a casing
18
, and a compressor side impeller
21
and a turbine side wheel
22
that are fixed to the rotary shaft
20
.
The compact gas turbine
17
is provided with a combustor
23
and a regeneration heat exchanger
24
. A coupling
25
is disposed between the rotor
4
of the generator
1
and the rotary shaft
20
of the compact gas turbine
17
.
The operation of the generator
1
and the compact gas turbine
17
will next b explained.
The compact gas turbine
17
is started by a starting motor incorporated in the generator
1
or a driving motor (not shown). Then, the rotary shaft
20
, the compressor side impeller
21
and the turbine side wheel
22
are rotated. Along these rotations, the atmospheric air (shown by a one-point chain line arrow mark in
FIG. 13
) is taken in and compressed by the compressor side impeller
21
. The compressed air (shown by a solid line arrow mark in
FIG. 13
) is mixed with fuel (such as a town gas, for example), and is combusted by the combustor
23
. This combustion gas (shown by a dotted line arrow mark in
FIG. 13
) rotates the turbine side wheel
22
, is heat-exchanged with the compressed air by the regeneration heat exchanger
24
, and is discharged to the atmosphere.
When the turbine side wheel
22
rotates at a high speed, the rotary shaft
20
rotates at a high speed. The high-speed rotation of the rotary shaft
20
is decelerated via the coupling
25
, and is transmitted to the rotor
4
of the high-speed generator
1
. When the rotor
4
rotates at a high speed, for example, at about 50,000 to about 80,000 rpm, the generator
1
carries out power generation.
On the other hand, in the generator
1
, cooling oil (shown by a one-point chain line in
FIG. 14
) has been supplied to the cooling oil entrance
9
, and lubricating oil (shown by a two-point chain line in
FIG. 14
) has been supplied to the lubricating oil entrance
12
, respectively. The cooling oil passes through the cooling oil passage
11
and the external periphery of the stator
6
from the cooling oil entrance
9
, thereby cooling the external periphery side of the stator
6
, and is discharged to the outside from the cooling oil exit
10
. Further, the lubricating oil passes through the lubricating oil passage
14
from the lubricating oil entrance
12
, thereby lubricating the bearing
3
and the like, and is discharged to the outside from the lubricating oil exit
13
.
In the generator
1
, based on its structure, lost energy is accumulated as heat on the inside. In other words, when the rotor
4
rotates at a high speed, a high frequency is generated, and an eddy current is generated. Based on this, the rotor
4
and the stator
6
are heated. When the temperature of the rotor
4
and the stator
6
rise, a magnetic flux declines and power generation efficiency is lowered. Therefore, it is necessary to cool the rotor
4
and the stator
6
in the generator
1
. Incidentally, when the power generation capacity of the generator
1
exceeds about 50 kw or more, for example, the temperature of the rotor
4
and the stator
6
become about 150 to 180° C. when the temperature of the open air is about 50° C. Therefore, it is necessary to cool the rotor
4
and the stator
6
to a temperature of about 140° C. or below as described above.
However, according to the cooling structure of the conventional generator
1
, the cooling oil passage
11
is provided between the internal periphery of the casing
2
and the external periphery of the stator
6
. Therefore, it is possible to cool the external periphery side of the stator
6
with the cooling oil but it is difficult to cool the internal periphery side of the stator
6
and the rotor
4
. As a result, there is a problem that it is not possible to obtain an effective cooling effect.
Therefore, this invention has an object of providing a generator cooling structure that effectively cools the generator.
DISCLOSURE OF THE INVENTION
According to the present invention, a casing is provided with a cooling oil entrance and a cooling oil exit. On the other hand, an iron core is provided with a cooling oil passage that passes through the inside of the iron core and is communicated between the cooling oil entrance and the cooling oil exit.
As a result, according to this invention, based on the cooling oil passage that passes through the inside of the iron core, the cooling oil passes through the inside of the iron core to cool the inside of the iron core. Therefore, it is possible to effectively cool the internal periphery side of the stator and the rotor.
Further, according to the present invention, a casing is provided with a cooling air entrance and a cooling air exit. On the other hand, an iron core is provided with a cooling air passage that passes through the inside of the iron core and is communicated between the cooling air entrance and the cooling air exit via a clearance between the internal periphery of the iron core and the external periphery of the rotor.
As a result, according to this invention, based on the cooling air passage, cooling air passes through the inside of the iron core and the clearance between the internal periphery of the iron core and the external periphery of the rotor to cool the inside of the iron core and the rotor. Therefore, it is possible to effectively cool the internal periphery side of the stator and the rotor.
Further, according to this invention, as the cooling air cools the external periphery of the rotor, the cooling oil does not easily enter the external periphery of the rotor due to the centrifugal force of the rotor, as compared with when the cooling oil cools the external periphery of the rotor. Therefore, there is no possibility that the cooling oil passage is corroded. Further, as compared with the cooling oil, the

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