Note: Descriptions are shown in the official language in which they were submitted.
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ROTOR
TECHNICAL FIELD
The present invention relates to a rotor, and more particularly, to a rotor
relatively rotating
with respect to a stator in a generator or a motor.
BACKGROUND
A generator, a motor, and the like perform a desired function by rotating a
rotor by an
electromagnetic interaction between the rotor and a stator. The rotor is
required to be lighter, since
the rotor relatively rotates with respect to the stator.
Since the rotor rotates with respect to the stator for a long time though the
electromagnetic
interaction, it is necessary to smoothly dissipating heat generated in the
rotor and the stator to the
outside.
However, a hydraulic turbine generator having a rotary shaft that is several
meters long and
on which a rotor is disposed has a problem in that heat is not properly
dissipated from a middle
portion in the lengthwise direction of such a rotary shaft.
In addition, since heat is not properly dissipated from a coil portion of the
rotor
corresponding to the middle portion in the lengthwise direction of the rotary
shaft that is several
meters long, the hydraulic turbine generator has a problem in that operation
performance of a rotor
or a stator is reduced, or the rotor or the stator is damaged by heat. This is
because the middle
portion in the lengthwise direction of the rotary shaft that is several meters
long is a portion to which
it is most difficult for outside air be supplied.
Since rotors of existing rotors used in a large hydraulic turbine generator
are heavy, it is
necessary to remove elements interrupting rotation through lightening and to
facilitate a movement
of the rotors after the manufacture of the rotors.
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SUM MARY
Technical Problem
Accordingly, the present invention has been made keeping in mind the above
problems
occurring in the prior art, and an object of the present invention is to
reduce the weight of a rotor
used in a large generator or a large motor.
Another object of the present invention is to allow heat to be smoothly
dissipated from a
central portion in the lengthwise direction of a rotor used in a large
generator or a large motor.
Technical Solution
ln order to achieve the above object, according to one aspect of the present
invention, there is
provided a rotor including: a rotary shaft having support portions and a
hollow part in which an inner
space and inflow holes are formed, the support portions being disposed at both
ends of the hollow
part, and the inflow holes allowing outside air to flow into the inner space
therethrough; and salient
poles disposed at predetermined intervals on an outer surface of the hollow
part. Ejection holes are
opened through portions of the outer surface of the hollow part, placed
between the salient poles such
that while air that has entered the inner space of the hollow part is being
discharged to an outside
through the ejection holes, the air dissipates heat from the hollow part and
the salient poles.
A plurality of the ejection holes may be formed in the outer surface of the
hollow part and
arranged from a region corresponding to a middle portion in a lengthwise
direction of the hollow part
to both ends of the hollow part.
The inner space formed in the hollow part may be opened though the both ends
of the hollow
part, flanges disposed at end portions of the support portions may be attached
together to the hollow
part, and inflow holes may be formed in the flanges to allow cooling air to
enter the inner space.
A plurality of the inflow holes may be formed to form a circular trajectory
along the flanges.
Through-holes may be formed in the flanges, the though-holes being penetrated
by coupling
members connecting the flanges disposed at the end portions of the support
portions disposed at the
both ends of the hollow part.
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The through-holes may be disposed in positions of the flanges, corresponding
to positions on
which the salient poles are disposed.
According to one aspect of the present invention, there is provided a rotor
including: a rotary
shaft; a hollow part allowing the rotary shaft to penetrate a central portion
thereof, the hollow part
having an inner space therein opened through both sides thereof; shaft spiders
supporting the hollow
part with respect to the rotary shaft; and salient poles disposed at
predetermined intervals on an outer
surface of the hollow part. While air in the inner space is being discharged
to the outside through
portions of the outer surface of the hollow part, placed between the salient
poles, the air dissipates heat
from the hollow part and the salient poles.
The hollow part may have a plurality of ejection holes in the outer surface
thereof, through
which the air in the inner space is discharged, the plurality of ejection
holes being arranged from a
region corresponding to a middle portion in a lengthwise direction of the
hollow part to both ends of
the hollow part.
The hollow part may be formed by stacking a plurality of boards, and the air
in the inner
I 5 space is discharged through the outer surface by forming gaps between
the plurality of boards.
The ejection holes and the gaps may be disposed in the outer surface of the
hollow part,
between regions on which the salient poles are mounted.
Advantageous Effects
As described above, a rotor according to the present invention has advantages
as follows.
First, in the present invention, since a hollow part is disposed in a middle
portion in the
lengthwise direction of a rotary shaft and heat is dissipated from a rim core
and salient poles while
air flows into the hollow part and is discharged in the centrifugal direction
of the rotor, heat is more
smoothly dissipated from the rotor. It is possible to prevent local
deterioration and improve a
lifespan and performance of a device by smoothly supplying cooling air to a
rotor center to which
the cooling air has difficulty in accessing.
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In the present invention, since the hollow part is disposed in the middle
portion in the
lengthwise direction of the rotary shaft, the weight of the rotor is reduced
as a whole. In particular,
since the rotary shaft has support portions at both ends thereof and a hollow
part at a middle portion
thereof, weight may be reduced due to the hollow part. Accordingly, energy
consumed to rotate the
rotor may be minimized, thereby minimizing an effort necessary for handing
such as a transfer or the
like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view illustrating a configuration of a
rotor according
to a preferred embodiment of the present invention.
FIG. 2 is a front view illustrating a configuration of a rotary shaft viewed
from one end of
the rotor, according to an embodiment of the present invention.
FIG. 3 is an exploded perspective view illustrating a main configuration
according to an
embodiment of the present invention.
FIG. 4 is an operation state view illustrating a state in which air flows in
the rotor,
according to an embodiment of the present invention.
FIG. 5 is a longitudinal cross-sectional view illustrating a configuration
according to
another embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating the configuration according to
the embodiment
shown in FIG. 5.
FIG. 7 is an operation state view illustrating a state in which air flows in
the embodiment
shown in FIG. 5.
Mode for Invention
Hereinafter, some embodiments of the present invention will be described in
detail with
reference to the exemplary drawings. It is to be noted that in giving
reference numerals to
elements of each drawing, like reference numerals refer to like elements even
though like elements
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are shown in different drawings. Further, in describing embodiments of the
present invention,
well-known functions or constructions will not be described in detail since
they may unnecessarily
obscure the understanding of the present invention.
It will also be understood that, while terms such as "first," "second," "A,"
"B," "(a)," and
"(b)" may be used herein to describe various elements, such terms are merely
used to distinguish
one element from another element. The substance, sequence, order, or number of
these elements is
not limited by these terms. It will be understood that when an element is
referred to as being
"connected," or "coupled," to another element, it can be directly connected or
coupled to the other
element or intervening elements may be present.
As shown in drawings, a rotor according to an embodiment of the present
invention is used
in a rotary device such as a generator or a motor, in particular, a large
generator or a large motor.
A rotational center of the rotor becomes a rotary shaft 10. The rotary shaft
10 has a length of
several meters in the present invention. The rotary shaft 10 has support
portions 12 at both ends
thereof and a hollow part 14 at a middle portion thereof. The support portions
12 are rotatably
supported by bearings (not shown) disposed in a housing of a rotary device.
The support portions
12 have a cylindrical shape in the present embodiment. Of course, the support
portions 12 have a
tubular shape. The support portions 12 may have any shape as long as at least
the outer surfaces of
portions thereof supported by the bearings are circular.
Flanges 16 are formed at both ends of the support portions 12. The Flanges 16
are formed
in a disc shape. A plurality of inflow holes 18 are formed so as to penetrate
the flange 16. The
inflow holes 18 are configured to allow outside air to flow into an inner
space 20 described below.
The plurality of inflow holes 18 are formed in the flange 16, and a trajectory
thereof forms a circular
shape. The inflow holes 18 and the formation trajectories thereof may have
various shapes
according to a design condition.
On the other hand, the flanges 16 are coupled through a bolt (not shown) for
connecting the
support portions 12 at the both ends to each other. To this end, through-holes
(not shown) may be
formed in the flanges 16 and may be placed on a trajectory equal to or
different from the trajectory
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of the inflow holes 18. The through-holes are not illustrated in drawings for
convenience of
description. A connection structure between the support portions 12 and the
hollow part 14 may
be variously designed. However, the connection hole should be designed such
that the bolt
penetrating the through-hole does not hinder air from flowing through ejection
holes 22.
The inner space 20 is formed in the hollow part 14. The inner space 20 is
opened though
both ends of the hollow part 14, and opened portions of the inner space 20 are
shielded from the
outside by the flanges 16. Stepped portions 21 are formed on inner surfaces of
both inlets of the
inner space 20, respectively. The stepped portions 21 are portions on which
the flanges 16 are
stably disposed. An inner diameter of the inner space 20 inside of the stepped
portions 21 is
smaller than an inner diameter of the inner space 20 outside of the stepped
portions 21. The
flanges 16 do not enter the inner space 20 with respect to the stepped
portions 21.
The hollow part 14 acts as a rim core, and salient poles 24 described below
are mounted on
the outer surface of the hollow part 14. A plurality of ejection holes 22
penetrate the hollow part
14 to be opened through the outer surface of the hollow part 14. The inner
space 20 communicates
with the outside through the ejection holes 22. The ejection holes 22 are
intensively formed in a
central region in the lengthwise direction of the hollow part 14, so as to
efficiently dissipate heat
from middle portions of the salient poles 24. In particular, the ejection
holes 22 are formed to be
opened through the outer surface of the hollow part 14, on which the salient
poles 24 described
below are not mounted. The plurality of ejection holes 22 are formed in the
outer surface of the
hollow part 14 from a region corresponding to a middle portion in the
lengthwise direction of the
hollow part 14 to both ends of the hollow part 14.
While air entering the inner space 20 through the inflow holes 18 is
discharged though the
ejection holes 22, the air dissipates heat from the hollow part 14 itself and
the salient poles 24 to the
outside. As shown in FIG. 3, the ejection holes 22 are formed to be opened
though a region of the
outer surface of the hollow part 14, on which the salient poles 24 are not
formed. The plurality of
ejection holes 22 form a line or are formed in a predetermined region.
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The salient poles 24 are mounted on the hollow part 14, i.e., the outer
surface of the rim
core. The salient poles 24 are formed by winding a coil on a stacked core. A
plurality of salient
poles 24 are mounted at predetermined intervals on the hollow part 14. The
salient poles 24 may
be mounted on the outer surface of the hollow part 14 by using a dovetail
structure or a bolt.
A plurality of cooling fans 26 are disposed along edges of both ends of the
hollow part 14.
The cooling fans 26 naturally guide air according to the rotation of the rotor
to allow cooling air to
flow toward the salient poles 24 and the outer surface of the hollow part 14.
The locations and the
number of the cooling fans 26 are changed according to a design condition of
the rotor.
As shown in FIGS. 5 to 7, a rotary shaft 110 is provided at the rotational
center of the rotor
according to the present embodiment. The rotary shaft 110 has support portions
112 on both ends,
supported by bearings (not shown). The support portions 112 are rotatably
supported by the
bearings (not shown) disposed in the housing of a rotary device.
A plurality of shaft spiders 113 are disposed along an outer surface of the
rotary shaft 110.
A hollow part 114 is disposed across a predetermined region from a middle
portion in the
lengthwise direction of the rotary shaft 110 to both ends of the rotary shaft
110 by the shaft spiders
113. The hollow part 114 is formed in a tubular shape and acts as a rim core.
An inner space 116
is formed in the hollow part l 14. The rotary shaft 110 penetrates a center of
the inner space 116,
and the shaft spiders 113 connect an inner surface of the inner space 116 and
the rotary shaft 110.
The inner space 116 has both opened ends to communicate with the outside.
A plurality of ejection holes 118 are formed so as to penetrate the hollow
part 114 and are
opened through an outer surface of the hollow part 114. The inner space 116
communicates with
the outside through the ejection holes 118. The ejection holes 118 are
intensively formed in a
central region in the lengthwise direction of the hollow part 114, so as to
effectively dissipate heat
from a middle portion of salient poles 120 described below. In particular, the
ejection holes 118
are formed to be opened through the outer surface of the hollow part 114, on
which the salient poles
120 described below are not mounted. The plurality of ejection holes 118 are
formed in the outer
surface of the hollow part 114 from a region corresponding to a middle portion
in the lengthwise
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direction of the hollow part 114 to both ends of the hollow part 114. For
reference, the hollow part
114 may be formed by stacking a plurality of boards. In this case, gaps may be
formed between
the boards to substitute for the ejection holes 118.
While air entering the inner space 116 through the both ends of the inner
space 116 is
discharged though the ejection holes 118, the air dissipates heat from the
hollow part 114 itself and
the salient poles 120 to the outside. As shown in FIG. 6, the ejection holes
118 are formed to be
opened though a region of an outer surface of the hollow part 114, on which
the salient poles 120
are not formed. The plurality of ejection holes 118 form a line or are formed
in a predetermined
region.
The salient poles 120 are mounted on the hollow part 114, i.e., an outer
surface of the rim
core. The salient poles 120 are formed by winding a coil on a stacked core. A
plurality of salient
poles 120 are mounted at predetermined intervals on the hollow part 114. The
salient poles 120
may be mounted on the outer surface of the hollow part 114 by using a dovetail
structure or a bolt.
A plurality of cooling fans 122 are disposed along edges of both ends of the
hollow part
114. The cooling fans 122 naturally guide air according to the rotation of the
rotor to allow
cooling air to flow toward the salient poles 120 and the outer surface of the
hollow part 114. The
locations and the number of the cooling fans 122 may vary according to the
design condition of the
rotor.
Hereinafter, uses of the rotor having the aforementioned configuration
according to the
present invention will be described in detail.
First, in the embodiment shown in FIG. 1, the rotor 10 is formed by coupling
the flanges l 6
of the support portions 12 and the stepped portions 21 in both inlets of the
inner space 20 in a state
in which the flanges 16 closely contact the stepped portions 21. Since weight
corresponding to a
volume of the inner space 20 is removed due to the formation of the inner
space 20 in the hollow
part 14, the aforementioned rotary shaft 10 is relatively lighter than a rotor
having the same size.
When the plurality of salient poles 24 are mounted at predetermined intervals
on the outer
surface of the hollow part 14 as shown FIG. 2, the assembly of the rotor is
completed. The rotor as
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formed above is disposed in a space formed in a stator in a rotary device such
as a generator or a
motor. At this time, the support portions 12 at the both ends are supported by
the bearings
disposed in the housing of the rotary device.
The rotor disposed in the rotary device rotates by an electromagnetic
interaction with a
stator. That is, the rotor rotates by an electromagnetic interaction between a
coil of the salient
poles 24 and a coil of the stator. When the aforementioned rotation is
generated by the
electromagnetic interaction, heat is generated in the coils. When the heat is
not smoothly
dissipated to the outside, rotation performance of the rotor is reduced, or
the rotor is damaged.
The dissipation of heat generated in the rotor and the stator will be
described with reference
to FIG. 4. When the rotary shaft 10 rotates, the cooling fans 26 operate
integrally with the rotary
shaft 10, and the operation of the cooling fans 26 forms a current of air. The
current of air is
directly transmitted to the salient poles 24 and the outer surface of the
hollow part 14. The
plurality of cooling fans 26 are disposed along edges of both ends of the
hollow part 14 and allow
air to flow from both ends in the lengthwise direction of the hollow part 14
to a middle portion of
the hollow part 14. The current of air as formed above absorbs heat while
contacting the salient
poles 24 and the outer surface of the hollow part 14.
However, when the rotary shaft 10 rotates, air around the salient poles 24
forms a current of
air in the centrifugal direction. Accordingly, most of current of air formed
by the cooling fans 26
is not transferred to a center portion of the salient poles 24 and is
transferred to the stator. Since
the pressure of air inside the center portion of the salient poles 24 and the
hollow part 14 is lowered,
air is discharged from the inner space 20 to the outside of the hollow part 14
through the ejection
holes 22 opened though the outer surface of the hollow part 14.
Since air flows into the inner space 20 through the inflow holes 18 formed in
the flanges 16
of the support portions 12 at the both ends, air flows in the inner space 20
encounter each other near
the ejection holes 22, and the air is discharged to the outside through the
ejection holes 22.
The air discharged through the ejection holes 22 acts to dissipate heat from a
region
corresponding to a middle portion in the lengthwise direction of the rotor.
Therefore, the cooling
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fans 26 may compensate a fact that a current of air formed from the both ends
to the middle portion
of the salient poles 24 does not reach the middle portion of the salient poles
24 and flows in the
centrifugal direction of the rotor not to dissipate heat from the middle
portion, and thus the middle
portion is overheated.
In other words, the ejection holes 22 of the hollow part 14 are configured to
intensively
transfer air to a central region in the lengthwise direction of the hollow
part 14 and a central portion
of the salient poles 24 to intensively dissipate heat from a corresponding
portion. Therefore, heat
generated by the rotor may be entirely and smoothly dissipated to the outside.
As described above, currents of air formed in the centrifugal direction from
the rotor are
constantly maintained with respect to an entire region in the lengthwise
direction of the rotor by the
ejection holes 22, and thus, a current of air transmitted to the stator is
uniform as shown in FIG. 4.
Accordingly, heat generated in the stator may be smoothly dissipated.
On the other hand, since the dissipation of heat in the embodiment shown in
FIGS. 5 to 7 is
similar to the dissipation of heat in the embodiment described above, the
description will be simply
provided. That is, when the rotary shaft 110 rotates, an atmospheric pressure
is lowered in the
inner space 116 of the hollow part 114. Accordingly, air is transferred from
the inner space 116 to
the outside of the hollow part 114 through the ejection holes 118 as shown in
FIG. 7. Of course,
currents of air formed by the cooling fans 122 are formed along the outer
surface of the hollow part
114 to cool the salient poles 120.
Here, air discharged from the inner space 116 through the ejection holes 118
may
intensively dissipate heat to the outside from the salient poles 120 and the
middle portion of the
hollow part 114.
Although the exemplary embodiments of the present disclosure have been
described for
illustrative purposes, those skilled in the art will appreciate that various
modifications, additions and
substitutions are possible, without departing from essential characteristics
of the disclosure.
Therefore, exemplary embodiments of the present disclosure have not been
described for limiting
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purposes. Accordingly, the scope of the disclosure is not to be limited by the
above embodiments
but by the claims and the equivalents thereof.
In the embodiments described for reference, the flanges 16 of the support
portions 12 are
coupled to the hollow part 14 through the bolt, but the embodiments are not
necessarily limited
thereto. For example, the flanges 16 of the support portions 12 may be
directly coupled to the
hollow part 14 without using the bolt, or the support portions 12 may be
integrally formed into the
hollow part 14. That is, the rotary shaft 10 may be manufactured by using a
three-dimensional
(3D) printer to integrally form the support portions 12 and the hollow part
14.
As in the embodiments shown, when the support portions 12 and the hollow part
14 are
separately formed and are coupled to each other, air may also flow into the
inner space 20 though
gaps or the like between the flanges 16 and the hollow part. In this case, the
gaps become the
inflow holes 18.
The inflow holes 18 and the ejection holes 22 are illustrated in the
embodiments as being
formed in a circular shape, but the embodiments are not limited thereto. The
inflow holes 18 and
the ejection holes 22 may have not only the circular shape, but also a variety
of other shapes, such as
an oval shape and a polygonal shape.
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