[DESCRIPTION]
[Title of Invention]
VIBRATION CONTROL APPARATUS, WIND TURBINE GENERATOR
AND VIBRATION CONTROL METHOD
5
[Technical Field]
[0001]
The present invention relates to a vibration
control apparatus and a vibration control method for
10 damping vibration of a structure as well as a wind
turbine generator.
[Background Art]
[0002]
15 A damping device is normally used to damp the
vibration of the structure. For instance, Patent
Literature 1 discloses a vibration control apparatus
having a damping unit of an inverted pendulum type.
The vibration control apparatus includes a weight mass,
20 a rod which is installed upright to support the weight
like an inverted pendulum, a supporting member which
sup-ports the middle part of the rod as a supporting
point of the inverted pendulum, a drive unit which
moves a lower end of the rod in a desired direction
25 and a spring whose one end is connected to the rod and
whose other end is connected to an object whose
vibration is controlled.
[0003]
For instance, another vibration control apparatus
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is described in Patent Literature 2. The vibration
control apparatus includes a pendulum damping unit and
an inverted-pendulum damping unit. The pendulum
damping unit has a first weight suspended from the top
5 of the object to be controlled. The inverted pendulum
dumping unit has a second weight supported by a rod
installed upright on the bottom of the object. The
first and second weight are freely movable in a
vertical direction and are interlocked by a connection
10 member for moving the first and second weights in
conjunction in a horizontal direction.
[0004]
Yet another vibration control apparatus is
described in Patent Literature 3. The vibration
15 control apparatus includes an inverted-pendulum
damping unit and a rotation damping unit utilizing
rotatory inertia. The inverted-pendulum damping unit
is installed upright on the bottom of the object to
support a weight by a multiple layers of laminated
20 rubbers. The rotation damping unit has a shaft which
rotates while moving in a horizontal direction in
conjunction with a movement of a weight unit having a
plurality of weights connected thereto, a cable winded
around the shaft and a cable mount to which both ends
25 of the cable are connected via a linear guide.
[Citation List]
[Patent Literature]
[0005]
11-074PCT
[PTL 1]
JP4-008944A
[PTL 2]
JP11-037212A
5 [PTL 3]
JP2000-310276A
[Summary of Invention]
[Technical Problem]
10 [0006]
Recently, the wind turbine generators are getting
larger in pursuit of higher power generation
efficiency. Some wind turbine generators are over
100m in hub height (height from the ground to the
15 center of the hub). In response to the increased size
of the wind turbine generator, a natural period of the
first natural frequency of a tower increases. When
the period of the first natural frequency of the tower
coincides with a resonance zone of the rotor rotation,
20 the fatigue load on the tower increases substantially.
Thus, it is necessary to install a vibration control
apparatus in the wind turbine generator.
The inside the tower of the wind turbine generator
is occupied by a hoistway or stairway which the
25 workers use to perform maintenance of the nacelle
installed on the tower and a variety of pipes and
cables. This leaves a limited space for installing
the vibration control apparatus.
[0007]
3
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The vibration control apparatus of Patent
Literature 1 and Patent Literature 2 requires a large
space for installation. Thus, it is difficult to
install the vibration control apparatus of Patent
5 Literature 1 and Patent Literature 2 inside the tower
of the wind turbine generator.
The vibration control apparatus of Patent
Literature 3 has a reduced height enough to be
installed in a small space. However, it requires
10 machining with high precision so that the weight unit
and the shaft can smoothly rotate. Thus, the
production of the vibration control apparatus is
expensive.
[0008]
15 In view of the problems above, it is an object of
the present invention is to provide a vibration
control apparatus that can be installed in a small
space and can be produced at low cost, as well as a
wind turbine generator equipped with the vibration
20 control apparatus and a vibration control method.
[Solution to Problem]
[0009]
To solve the problems described above, the present
25 invention provides a vibration control apparatus for a
structure. The vibration control apparatus may
include, but is not limited to: a first vibration
system which comprises a first weight, a supporting
bar installed upright on the structure to support the
4-
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first weight on the structure, a lower universal joint
connecting a lower end of the support bar to the
structure and an upper universal joint connecting an
upper end of the support bar to the first weight; a
5 second vibration system which comprises an elastic
member installed upright on the structure and a second
weight arranged on the, elastic member; and a
restraining unit which restrains the first weight with
respect to the second weight such that the first and
10 second weights move in the same direction on the same
horizontal plane and the first weight moves relative
to the second weight in a vertical direction.
[0010]
According to the above vibration control apparatus,
15 the first weight and the second weight are supported
from underneath by the supporting bar and the elastic
member respectively. Thus, it is possible to control
the height of the device in comparison to the
conventional control apparatus having the pendulum-
20 type damping unit in which the weight is suspended
from the structure via the suspension member and the
inverted-pendulum damping unit in which another weight
is supported by the supporting bar.
The first vibration system and the second
25 vibration system can be manufactured by using general
parts without using special materials and thus, the
control apparatus can be manufactured at low cost.
The replacement parts are easily-available for
maintenance or the like, as the general parts are used.
I 1-074PCT
[0011]
In the above vibration control apparatus for the
structure, the first vibration system and the second
vibration system move on the same horizontal plane in
5 the same direction and the first vibration system
moves relative to the second vibration system in the
vertical direction. Specifically, the first and
second vibration systems are integrated such as to
restrain a degree of horizontal-movement freedom
10 without restraining a degree of vertical-movement
freedom. In this manner, it is easy to adjust the
oscillation cycle of the vibration control apparatus
by changing the weight ratio of the first weight and
second weight while the vertical movement thereof is
15 unrestricted.
[0012]
The restraining unit may include, but is not
limited to, a frame which surrounds the first weight
and a plurality of sliding members which are provided
20 between an outer periphery of the first weight and an
inner periphery of the frame.
According to the above restraining unit, the
sliding members are provided between the frame of the
second weight and the first weight so that the second
25 weight moves smoothly relative to the first weight in
the vertical direction. The frame of the second
weight surrounds the first weight and thus, the first
weight and the second weight move together in the same
direction on the same horizontal plane. In this
6
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manner, the first weight and the second weight move
together in the same direction on the same horizontal
plane and the first weight moves relative to the
second weight in the vertical direction.
5 [0013]
At least one of the first and second weights may be
formed by a plurality of weight pieces each of which
is detachable.
At least one of the first and second weights is
10 formed by detachable weight pieces. Thus, it is
possible to adjust the natural frequency of the
vibration control apparatus by changing the weight
ratio of the first weight and second weight,
specifically by changing the number of the weight
15 pieces of at least one of the first weight and second
weight.
In the above vibration control apparatus, the
first and second vibration systems are integrated such
as to restrain a degree of horizontal-movement. freedom
20 without restraining a degree of vertical-movement
freedom. In this manner, it is easy to adjust the
oscillation cycle of the vibration control apparatus
by changing the weight ratio of the first weight and
second weight while the vertical movement thereof is
25 unrestricted.
For instance, when the first natural frequency
varies in installation stages such as a stage of
constructing a low tier of the structure, a stage of
constructing a middle tier and a stage of constructing
7
I 1-074PCT
a top tier, the vibration control apparatus can adjust
the natural frequency. Thus, it is possible to
efficiently damp the vibration occurring in each of
the stages by installing the vibration control
5 apparatus in course of construction of the structure.
For instance, in the case of the wind turbine
generator, installing of the vibration control
apparatus in the stage of structuring the tower is
particularly advantageous in stages such as a stage of
10 structuring the tower and a stage of installing the
nacelle to the tower.
At least one of the first and second weights is
formed by the detachable weight pieces. Thus, it is
easy to adjust the oscillation cycle by changing the
15 number of the detachable weight pieces of the one of
the first and second weights and workers with general
skill can perform the process without using any
special tool. Therefore, it is unnecessary to arrange
a skilled operator or special tool to adjust the
20 oscillation cycle.
[0014]
The structure may be a wind turbine generator.
In such case, it is possible to damp the first natural
vibration of the tower due to the rotation of the
25 blades of the wind turbine generator. Therefore, the
wind turbine generator having the hub which is over
100m height, is easily achievable while avoiding the
increase of the weight and a wall thickness of the
tower and maintaining an appearance and inside
8
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structure of the tower.
[0015]
When the structure is the wind turbine generator,
the vibration control apparatus is installed in a
5 tower of the wind turbine generator, and a pair of the
second vibration systems may be provided on both sides
of the first vibration system in a circumferential
direction of the tower,
sliding members may be
10 the second vibration
integrally formed with
the first weight, each
and a frame and a plurality of
provided between the pair of
systems, the frame being
the second weight to surround
of the sliding members being
arranged between the first weight and the frame.
According to the above vibration control, the pair
15 of second vibration systems are provided on both sides
of the first vibration system in the circumference
direction of the tower. Thus, the vibration control
apparatus is substantially shaped into an arc formed
along the inner wall of the tower. It is possible to
20 install the arc-shaped vibration control in a small
space between the inner wall of the tower and an outer
periphery of a stairway which is generally arranged in
the center of the tower.
[0016]
25 It is also preferable that a weight ratio of the
first weight to the second weight is changed to adjust
a oscillation cycle of a main body of the vibration
control apparatus without changing a total weight of
the first and second weights.
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In this manner, the oscillation cycle of the main
body of the vibration control apparatus can be
adjusted without changing the total weight of the
first and second weights. Thus, it is unnecessary to
5 add a separate weight to adjust the oscillation cycle.
[0017]
The vibration control apparatus may also include a
damper one end of which is connected to the structure
and other end of which is connected to one of the
10 first and second weights.
The one end of the damper is connected to the
structure and the other end of the damper is connected
to one of the first and second weights. Thus, it is
possible to enhance the damping effect on the
15 horizontal vibration of the first and second weights.
[0018]
It is also preferable that the damper is arranged
horizontally.
With the damper installed horizontally, it is
20 possible to enhance the damping effect on the
horizontal vibration.
[0019]
The wind turbine generator in relation to the
present invention may include, but is not limited to,
25 the vibration control apparatus described above.
In such case, it is possible to damp the first natural
vibration of the tower due to the rotation of the
blades of the wind turbine generator. Therefore, the
wind turbine generator having the hub which is over
11-074PCT
100m height, is easily achievable without increasing
the weight and a wall thickness of the tower.
[0020]
The vibration control apparatus may be installed on
5 an upper floor of the tower of the wind turbine
generator.
In such case, in comparison to the case of the
vibration control apparatus being installed on a
middle floor or a lower floor of the tower of the wind
10 turbine generator, it is possible to efficiently damp
the first natural vibration of the tower.
[0021]
The present invention provides a vibration control
method for a structure. The vibration control method
15 may include, but is not limited to, the steps of:
installing upright a first vibration system comprising
a support bar and a first weight on the structure
by connecting one end of the support bar to the
structure, the supporting bar being connected to a
20 universal joint at both ends of the supporting bar,
the first weight being coupled to other end of the
support bar via the universal joint;
installing upright a second vibration system
comprising an elastic member and a second weight on
25 the structure by connecting one end of the elastic
member to the structure, the second weight being
connected to other end of the elastic member;
restraining the first weight with respect to the
second weight by a restraining unit; and
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11-074PCT
when the structure shakes, oscillating the first and
second weights such that the first and second
weights move in the same direction on the same
plane and the first weight moves relative to the
5 second weight in a vertical direction-
[0022]
According to the vibration control method, the
first and second vibration systems are installed
upright on the structure and the first and second
10 weights move on the same horizontal plane in the same
direction while the first weight moves relative to the
second weight in the vertical direction. Thus, it is
possible to enhance the damping effect on the first
natural vibration of the structure.
15 [0023]
In the above vibration control method, at least one
of the first and second weights may be formed by a
plurality of weight pieces each of which is detachable,
and the vibration control method may include the step
20 of changing a number of the weight pieces of at least
one of the first and second weights to change a weight
ratio of the first weight to the second weight.
In this manner, the number of weight pieces of at
least one of the first and second weights is changed
25 to change the weight ratio of the first and second
weight, thereby adjusting the natural frequency of the
vibration control as a whole having the first and
second vibration systems. Therefore, it is possible,
for instance, to damp the vibration of the structure
I 1-074PCT
according to the first natural frequency which varies
in installation stages such as a stage of constructing
a low tier of the structure, a stage of constructing a
middle tier and a stage of constructing a top tier.
5 For instance, in the case of the wind turbine
generator, installing of the vibration control
apparatus in the stage of structuring the tower is
particularly advantageous in stages such as a stage of
structuring the tower, a stage of installing the
10 nacelle to the tower and a stage of installing the
rotor to the nacelle.
[Advantageous Effects of Invention]
[0024]
15 According to the present invention, the first
weight and the second weight are supported from
underneath by the supporting bar and the elastic
member respectively. Thus, it is possible to reduce
the height of the vibration control apparatus and also
20 to manufacture the vibration control apparatus at low
cost.
[Brief Description of Drawings]
[0025]
25 FIG.1 is a side view illustrating a wind turbine
generator in relation to a first preferred embodiment
of the present invention.
FIG.2 is a fragmentary view taken along the line
A-A of FIG.l.
11-074PCT
FIG.3(a) is an enlarged view near a vibration
control apparatus of FIG.2.
FIG.3(b) is an enlarged view of the area D of
FIG.3(a).
5 FIG.4 is a fragmentary view taken along the line
B-B of FIG.3(a) showing a side view on a left-hand
side and a sectional view on a right-hand side.
FIG.5 is a fragmentary view taken along the line
C-C of FIG.3(a).
10 FIG.6 is a view shooing an operation of the
vibration control apparatus in relation to a preferred
embodiment of the present invention.
FIG.7 is a table showing an example case of a
relationship among a first weight, a second weight and
15 a natural frequency of the vibration control apparatus.
FIG.8(a) is a plane view of a vibration control
apparatus in relation to a second preferred embodiment
of the present invention.
FIG.8(b) is an enlarged view of the area E of
20 FIG.8(a).
FIG.9 is a plane view of a vibration control
apparatus in relation to a third preferred embodiment
of the present invention.
FIG.10 is a side view of the vibration control
25 apparatus in relation to the third preferred
embodiment of the present invention.
FIG.11 is a plane view of a vibration control
apparatus in relation to a fourth preferred embodiment
of the present invention.
11-074PCT
FIG.12 is a side view of the vibration control
apparatus in relation to the fourth preferred
embodiment of the present invention.
5 [Description of Embodiments]
[0026]
A preferred embodiment of the present invention
will now be described in detail with reference to the
accompanying drawings. Exemplary cases of applying a
10 vibration control apparatus to a wind turbine
generator are explained hereinafter. It is also
possible to apply the vibration control apparatus to
any structure that requires a vibration control
function such as a building, a plant, a bridge, a
15 tower and a crane. It is intended, however, that
unless particularly specified, dimensions, materials,
shape, its relative positions and the like shall be
interpreted as illustrative only and not limitative of
the scope of the present invention.
20 [0027]
FIG.l is a side view of a wind turbine generator 1
in -relation to a first preferred embodiment of the
present invention.
FIG.1 shows the wind turbine generator 1 which has
25 a tower 3 installed on a base 2, a nacelle 4 installed
on an upper end of the tower 3, a rotor 5. having a
plurality of blades 5B installed radially to a hub 5A
and a vibration control apparatus 7 installed on an
upper floor Ba of a plurality of floors 8 inside the
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tower 3.
The upper floor 8a has an opening 9 in the center
area. In the opening 9, a cable 53A, another cable
53B and a ladder 52 are inserted. The cable 53A
5 supplies electric power and a control signal to a
generator and a related device inside the nacelle 4.
The cable 53B supplies electric power from the
generator to a power grid. The cables 53A and 53B and
the ladder 52 are arranged along an inner wall of the
10 tower 3 between the base 2 and the upper floor 8a.
[0028]
The wind turbine generator 1 converts a force of
the wind against the blade 5B to a power to rotate the
rotor 5 around a rotation shaft. In such case, when
15 the first natural frequency of the tower 3 coincides
with the frequency of vibration accompanied by the
rotation of the rotor 5, it may cause the tower 3 and
the rotor 5 to resonate. In the preferred embodiment,
the vibration control apparatus 7 is provided to damp
20 the vibration of the tower 3 within a permissible
range even when the rotor 5 and the tower 3 resonate.
[0029]
FIG.2 is a fragmentary view taken along the line
A-A of FIG.l. FIG.3(a) is an enlarged view near a
25 vibration control apparatus of FIG.2. FIG.3(b) is an
enlarged view of the area D of FIG.3(a). FIG.4 is a
fragmentary view taken along the line B-B of FIG.3(a)
showing a side view on a left-hand side and a
sectional view on a right-hand side. FIG.5 is a
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fragmentary view taken along the line C-C of FIG.3(a).
As shown in FIG.2 to FIG.5, the vibration control
apparatus 7 includes a first vibration system 10, a
pair of second vibration systems 20, a restraining
5 unit 30 and a pair of dampers 40.
[0030]
The first vibration system 10 has a supporting bar
13 which is installed upright on a top surface of the
upper floor 8a via a universal joint 12 and a first
10 weight which is installed to an upper end of the
support bar 13 via a universal joint 12.
The upper and lower ends of the support bar 13 are
connected to the first weight 11 and the upper floor
8a via the universal joints 12 respectively. Thus,
15 the first vibration system 10 is in an invertedpendulum
state and does not stand on its own and is
unstable.
[0031]
The supporting bar 13 is a bar-shaped member which
20 extends in a vertical direction in a stationary state.
For instance, the bar-shaped member may be a hollow
cylindrical steel pipe, a H-shaped pipe or the like.
The first weight 11 is connected to the upper end
of the supporting bar 13. The first weight 11
25 includes a first container 15 and a plurality of
weight pieces 14 which are stacked and housed in the
first container 15. The first container 15 has a
tubular body whose cross-sectional shape is
quadrangular and a bottom plate which covers a hole on
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a bottom side of the tubular body.
The weight piece 14 has a.plate-like shape and has
the same horizontal-sectional shape as an inner
periphery of the first container 15. The weight
5 pieces 14 are interconnected with each other by a
linking member (unshown) so that the weight pieces 14
are fixed to one another without moving relative to
one another.
[0032]
10 The pair of second vibration systems 20 are
provided on both sides of the first vibration system
10 in the circumferential direction of the tower 3,
e.g. on left and right sides of the first vibration
system 10 as shown in FIG.3(a).
15 Each of the second vibration systems includes a
second weight 21 and a pair of elastic members 22
which are provided on the top surface of the upper
floor 8a and support the second weight 21. The pair
of elastic members 22 are coupled by a coupling member
20 100. The second weight 21 is supported by the pair of
elastic members 22. Thus, the second vibration system
20 is in an inverted-pendulum state but capable of
standing on its own in a stable manner.
The stable second vibration system 20 and the
25 unstable first vibration system 10 are combined to
form, the vibration control apparatus 7 with, a stable
vibration system structure.
[0033]
Each of the elastic members 22 is a laminated
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rubber formed by layering a plurality of rubbers 24
having a cylindrical shape. A supporting area and a
rubber thickness and so on are set to be capable of
vibrating the first and second weights 11 and 21 in a
5 desired oscillation cycle. The supporting area herein
means an area of an overlapping portion of the rubbers
24 stacked in a vertical direction.
[0034]
The second weight 21 is a column-shaped body and
10 has a cross-sectional shape of approximately rectangle.
The second weight 21 has a second container 16 with a
bottom and a plurality of weight pieces 25 which are
stacked in the second container 16.
At a corner part of each of the second containers
15 16 on a side nearer to the first weight 11, an
extension part 17 extends along the circumferential
direction of the tower 3.
The weight pieces 25 include the weight pieces 14
which form the first weight 11 as described above. In
20 the preferred embodiment, the weight piece 25 is
formed such that four of the weight pieces 14 and
weight pieces 25A and 25B are arranged on the same
plane. The weight pieces 25A and 25B have different
horizontal sectional shape than the weight pieces 14.
25 The weight piece 25, in a state that the weight pieces
14, 25A and 25B are connected, has a shape that is the
same as the horizontal sectional shape of the inner
periphery of the second container 16. The weight
pieces 25A and 25B may have the linking members on top
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I I-074PCT
and bottom surfaces to connect the weight pieces 25a
and 25B with another set of the weight pieces 25A and
25B respectively. The linking members are as
described above and unshown in the drawing.
5 In the preferred embodiment, the plate-like weight
pieces 14, the weight pieces 25a and 25B are used.
However, the shape of the weight pieces is not limited
to this and may be a rectangular column or the like.
[0035]
10 The weight piece 14 can be used for both the first
and second weights 11 and 21. Thus, the weight pieces
14 of the first weight 11 and the weight pieces 14 of
the second weight 21 are interchangeable. It is
possible to move some of the weight pieces 14 from one
15 of the first and second weights 11 and 21 to the other
of the first and second weights 11 and 21 so as to
change the weight ratio of the first and second
weights 11 and 21. In this manner , it is possible to
change the natural frequency of the vibration control
20 apparatus 7, which is described later in details.
[0036]
The restraining unit 30 includes a frame 35
surrounding the first weight 11 and a plurality of
sliding members installed between the first weight 11
25 and the frame 35.
[0037]
The frame 35 is formed by a side panel 18 of the
second container 16 on a side nearer to the first
weight 11, the extension part 17 of the second
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container 16 and a plate-like connection member 23
which connects the extension parts 17 and 17 of the
pair of neighboring second vibration systems 20 and 20.
The frame 35 is formed integrally with the second
5 weight 21. The extension part 17 and the connection
member 23 are connected by bolts 36.
In the preferred embodiment, the exemplary case
where the frame 35 is formed by the side panel 18 of
the second container 16, the extension part 17 and the
10 connection member 23 is explained. However, this is
not limitative and the frame 35 may be formed by a
rectangular cylindrical member. In such case, a pair
of opposing lateral surfaces of the rectangular
cylindrical member are respectively fixed to the side
15 panels 18 of the` neighboring second containers 16 by
the bolts so as to form the frame 35 integrally with
the second weight 21.
[00387
The plate-like sliding members 38 of the
20 restraining unit 30 are arranged so that the lateral
surfaces are in contact with the outer periphery of
the- first container 15 and the inner periphery of the
frame 35.
In the preferred embodiment, a linear guide which
25 is a linear motion bearing is used as the sliding
member 38.
The linear guide is formed by a guide 31 and a
sliding part 32. The guide 31 is installed to the
outer periphery of the first weight 11 along the
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vertical direction. The sliding part 32 is installed
to the inner periphery of the frame 35. The guide 31
is formed into a shape of a rectangular rod and has a
pair of grooves 46 formed along the longitudinal
5 direction on a pair of opposing lateral surfaces. The
sliding part 32 has a pair of projections 47 which are
engageable with the pair of grooves 46 of the frame 31.
The sliding part 32 is slidable along the guide 31 in
a state where the pair of projections 47 engage with
10 the pair of grooves 46.
In this manner, the first weight 11 to which the
guide 31 is installed slides smoothly in the vertical
direction relative to the frame 35 to which the
sliding part 32 is installed.
15 It is also possible to provide a friction
reduction plate such as a linear ball guide and an
oilless plate in an end part of the guide body on the
sliding part 32 side. The linear ball guide is
configured such that a plurality of spherical rolling
20 elements are embedded turnably in an end part of the
guide body on a side of the sliding part 32.
[0039]
In the preferred embodiment, the guide 31 is
installed to the first weight 11 and the sliding part
25 32 is installed to the second weight 21. However,
this is not limitative and it is possible to install
the guide 31 to the second weight 21 and the sliding
part 32 to the first weight 11.
[0040]
-22-
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As described above, the sliding members 38 are
arranged around the first weight 11 and are surrounded
by the frame 35 integrally formed with the second
weight 21. Thus, the first and second weights 11 and
5 21 move together in the same direction on the same
horizontal plane.
The sliding members 38 are installed between the
first weight 11 and the frame 35. Thus, the first
weight 11 slides in the vertical direction relative to
10 the second weight 21 with which the frame 35 is formed
integrally.
Specifically, the first and second vibration
systems 10 and 20 are integrated such as to restrain a
degree of horizontal-movement freedom without
15 restraining a degree of vertical-movement freedom.
As shown in FIG.6, the first weight 11 and the
second weight 21 move together on the same horizontal
plane in the same direction and the first weight 11
moves relative to the second weight 21 in the vertical
20 direction.
[0041]
The vibration control apparatus 7 also includes
the pair of dampers 40. One end of each of the
dampers 40 is connected to an inner wall of the tower
25 3 via a bracket 41 and other end of each of the
dampers 40 is connected to the upper end of the second
weight via a bracket 41.
The pair of dampers 40 are arranged at right
angles to each other so as to enhance the damping
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effect in every direction in the horizontal direction.
The dampers 40 may be oil dampers, viscoelastic
dampers or the like
In the preferred embodiment, the dampers 40 are
5 used. However, this is not limitative and it is
possible to increase friction resistance of the linear
guide of the sliding member 38 so as to absorb energy
of vibration by the increased friction.
[0042]
10 As described above, according to the vibration
control apparatus 7 of the preferred embodiment, the
weight ratio of the first weight 11 and the second
weight 21 can be changed. For instance, the weight
ratio is changed by removing the weight pieces 14 of
15 the first weight 11, by removing the weight pieces 14,
25A and 25B of the second weight 21, by removing the
weight pieces 14 of the first weight 11 and adding the
removed weight pieces 14 to the second weight 21, or
by removing the weight pieces 14 of the second weight
20 21 and adding the removed weight pieces 14 to the
first weight 11. The weight ratio of the first weight
11 and the second weight 21 is changed to adjust the
natural frequency of the vibration control apparatus 7.
The results of adjusting the natural frequency are
25 described below.
[0043]
The natural frequency of the vibration control
apparatus 7 in relation to the present invention is
calculated according to the formula (1) below.
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[Formula 1]
f
1 Id-n'29
=-
27r (1n, + nzz )l
Herein, f is a natural frequency (Hz), k is a
constant of spring of the elastic member 22 (N/m) C
5 is a distance (m) between a rotation center of the
universal coupling on the upper side and a rotation
center of the universal coupling 12 on the lower side,
ml is a weight (kg) of the first weight 11 and m2 is a
weight (kg) of the second weight 21.
10 [0044]
The formula (1) is used to calculate the natural
frequency in the case where the weight of the first
weight 11 is reduced per 1000kg and the weight of the
second weight 21 is increase per 1000kg while the
15 total weight (10000kg) of the first and second weights
21 is kept the same.
[0045]
FIG.7 is a table showing an example case of a
relationship among the first weight 11, the second
20 weight 21 and the natural frequency of the vibration
control apparatus 7.
As shown in FIG.7, when the first weight 11 is
10000kg and the second weight 21 is 0kg, the natural
frequency of the vibration control apparatus 7 is
25 1.000Hz.
[0046]
Then the weight of the first weight 11 is reduced
gradually and the weight of the second weight 21 is
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I 1-074PCT
increased by adding the reduced weight of the first
weight 11. For instance, the weight pieces 14 of the
first weight 11 are removed gradually and the removed
weight pieces 14 are added to the second weight 21.
5 In this manner, the natural frequency of the vibration
control apparatus 7 decreases gradually.
Finally, when the first weight 11 is 1000kg and
the second weight 21 is 9000kg, the natural frequency
of the vibration control apparatus 7 is 0.743Hz.
10 [0047]
According to the above results, it is confirmed
that the cycle of the vibration control apparatus 7 is
lengthened by gradually reducing the weight of the
first weight 11 and gradually increasing the weight of
15 the second weight 21 by adding the reduced weight of
the first weight 11.
[0048]
According to the vibration control apparatus 7 in
each of the preferred embodiments, the first weight 11
20 and the second weight 21 are supported from underneath
by the supporting bar 13 and elastic member 22
respectively. Thus, it is possible to control the
height of the device in comparison to the conventional
control apparatus having the pendulum-type damping
25 unit in which the weight is suspended from the
structure via the suspension member and the invertedpendulum
damping unit in which another weight is
supported by the supporting bar.
The first vibration system 10 and the second
-26-
11-074PCT
vibration system 20 can be manufactured by using
general parts without using special materials and thus,
the control apparatus 7 can be manufactured at low
cost.
5 [0049]
By installing the vibration control apparatus 7 to
the wind turbine generator 1, the first natural
vibration of the tower 3 due to the rotation of the
rotor 5 of the wind turbine generator 1 can be damped.
10 Therefore, the wind turbine generator 1 having the hub
5A which is over 100m height is easily achievable
without increasing the weight and a wall thickness of
the tower 3.
[0050]
15 The sliding members 38 are provided between the
frame 35 of the second weight 21 and the first weight
11 so that the second weight 21 moves smoothly
relative to the first weight 11 in the vertical
direction. The frame 35 of the second weight 21
20 surrounds the first weight 11 and thus, the first
weight 11 and the second weight 21 move together in
the_ same direction on the same horizontal plane. In
this manner, the first weight 11 and the second weight
21 move together in the same direction on the same
25 horizontal plane and the first weight moves relative
to the second weight in the vertical direction.
[0051]
At least one of the first and second weights 11
and 21 is formed by a plurality of weight pieces 14,
-27-
11-074PCT
25A and 25B which are detachable. For instance, the
weight pieces 14 of one of the first and second
weights 11 and 21 are moved to the other of the first
and second weights 11 and 21 so as to change the
5 weight ratio of the first and second weights 11 and 21.
In this manner, the natural frequency of the vibration
control apparatus 7 is adjusted.
[0052]
For instance, when the first natural frequency of
10 the tower 3 varies in installation stages such as
structuring the tower 3 and installing the nacelle 4
to the tower 3, the vibration control apparatus 7 can
adjust the natural frequency. Thus, it is possible to
efficiently damp the vibration occurring in each stage
15 by installing the vibration control apparatus 7 in the
stage of structuring the tower 3.
[0053]
The pair of the second vibration systems 20 are
provided on both sides of the first vibration system
20 10 in the circumferential direction of the tower 3.
By this, the vibration control apparatus 7 is formed
into an arc shape and can be arranged between the
outer periphery of the opening 9 formed in the center
of the tower and the inner wall of the tower 3.
25 [0054]
One end of the damper 40 is connected to, the tower
and other end of the damper 40 is connected to the
second weight 21 so as to increase the damping effect
on the vibration of the first and second weights 11
11-074PCT
and 21. The damper 40 is arranged horizontally and
thus, it is possible to enhance the damping effect on
the horizontal vibration.
[0055]
5 The vibration control apparatus 7 is provided on
the upper floor 8a of the tower 3. In comparison to
the case of the vibration control apparatus 7 being
installed on a middle floor or a lower floor 8 of the
tower 3, it is possible to efficiently damp the first
10 natural vibration of the tower 3.
[0056]
A second preferred embodiment of the present
invention is now described. the following
explanations, components already described in the
15 first preferred embodiment are denoted by the same
reference numerals, and thus detailed description
thereof are omitted and mainly differences are
described hereinafter.
[0057]-
20 FIG.8(a) is a plane view of a vibration control
apparatus 27 in relation to the second preferred
embodiment of the present invention. FIG.8(b) is an
enlarged view of the area E of FIG.8(a).
As shown in FIG.8, the vibration control apparatus
25 27 in relation to the second preferred embodiment of
the present invention includes a restraining unit 33
that is different from the vibration control apparatus
7 of the first preferred embodiment.
[0058]
-29-
11-074PCT
The restraining unit 33 includes the frame 35 and
a plurality of sliding members 39. The sliding
members 39 are provided in contact with the outer
periphery of the first weight 11 and the inner
5 periphery of the frame 35. In the second preferred
embodiment, oilless plates made of fluorine resin are
used as the sliding members 39. The oilless plates
are fixed to lateral surfaces of the outer periphery
of the first weight 11 by bolts 34. The oilless plate
10 may be oil impregnated sintered alloy which is
produced by combining special sintered alloy and a
steel back plate and contains lubricating oil which is
supplied across a sliding surface with a sliding
thereof.
15 In the preferred embodiment, the exemplary case of
using the oilless plate made of fluorine resin is
described. However, this is not limitative and it is
also possible to use a plate made of polyimide resin
or the like.
20 In the preferred embodiment, the exemplary case of
installing the oilless plate to the first weight 11 is
described. However, this is not limitative and it is
also possible to install the oilless plate to the
second weight 21.
25 [0059]
According to the vibration control apparatus 27 as
described above, the sliding members 39 are arranged
around the first weight 11 and surrounded by the frame
35 formed integrally with the second weight 21. Thus,
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11-074PCT
the first and second weights 11 and 21 move together
in the same direction on the same horizontal plane.
The first weight 11 to which the sliding members 39
are installed moves smoothly relative to the second
5 weight 21 in the vertical direction. As a result, the
first weight 11 and the second weight 21 moves
together in the same direction on the same horizontal
plane and the first weight 11 moves relative to the
second weight 21 in the vertical direction.
10 [0060]
A third preferred embodiment of the present
invention is described below.
[0061]
FIG.9 is a plane view of a vibration control
15 apparatus 37 in relation to the third preferred
embodiment of the present invention. FIG.10 is a side
view of the vibration control apparatus 37 in relation
to the third preferred embodiment of the present
invention.
20 As shown in FIG.9 and FIG.10, the vibration
control apparatus 37 in relation to the third
preferred embodiment includes a second vibration
system 26 and a restraining unit 43 that are different
from the vibration control apparatuses 7 and 27 of the
25 first and second preferred embodiments.
[0062]
The second vibration system 26 includes a second
weight 29 surrounding the first weight 11 and a
plurality of elastic members 22 supporting the second
-31-
11-074PCT
weight 29.
[0063]
The second weight 29 is configured by a third
container 48 and a plurality of weight pieces 28 which
5 are stacked and housed in the third container 48.
The third container 48 includes a rectangular
outer cylinder 49, a rectangular inner cylinder 50
installed in the outer cylinder 49 and a bottom plate
covering a lower end of a space formed between the
10 outer cylinder 49 and the inner cylinder 50. The
weight pieces 28 are stored in the space.
The weight pieces 28 are formed into the same
shape as the horizontal sectional shape of the inner
periphery of the third container 48. The weight
15 pieces 28 include the weight pieces 14 of the first
weight 11. In the preferred embodiment, the weight
pieces 28 is formed such that four of the weight
pieces 14 and weight pieces 51 having a different
horizontal sectional shape from the weight pieces 14
20 are arranged in the same plane. The weight pieces 14
of the second weight 29 and the weight pieces 14 of
the-first weight 11 are interchangeable.
[0064]
The restraining unit 43 includes a frame 44
25 surrounding the first weight 11 and the plurality of
sliding members 38.
In the preferred embodiment, the inner cylinder 50
of the second weight 29 is used as the frame 44. It
is also possible to provide a separate rectangular
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11-074PCT
cylindrical member as the frame 44. In such case, the
outer periphery of the frame 44 is fixed to the inner
periphery of the inner cylinder 50 of the second
weight 29 by a bolt or the like so as to integrate the
5 frame 44 with the second weight 29.
[0065]
According to the vibration control apparatus 37 as
described above, the, sliding members 38 are arranged
around the first weight 11 and surrounded by the
10 second weight 29. Thus, the first and second weights
11 and 29 move together in the same direction on the
same horizontal plane. The first weight 11 to which
the sliding members 38 are installed moves smoothly
relative to the second weight 29 in the vertical
15 direction. As a result, the first weight 11 and the
second weight 29 move together in the same direction
on the same horizontal plane and the first weight 11
moves relative to the second weight 29 in the vertical
direction.
20 [0066]
A fourth preferred embodiment of the present
invention is described below.
[0067]
FIG.11 is a plane view of a vibration control
25 apparatus 47 in relation to the fourth preferred
embodiment of the present invention. FIG.12,is a side
view of the vibration control apparatus 47 in relation
to the fourth preferred embodiment of the present
invention.
11-074PCT
As shown in FIG.11 and FIG.12, the vibration
control apparatus 47 in relation to the fourth
preferred embodiment includes a restraining unit 45
which is different from the vibration control
5 apparatus 37 of the third preferred embodiment.
The restraining unit 45 includes a plurality of
sliding members 39 installed between the first weight
11 and the frame 44.
In the same manner as the second preferred
10 embodiment, oilless plates are used as the sliding
members 39. The oilless plates are fixed to the
lateral surface of the first weight 11 by bolts 34.
According to the vibration control 47 described
above, the sliding members 39 are arranged around the
15 first weight 11 and surrounded by the second weight 29.
Thus, the first and second weights 11 and 29 move
together in the same direction on the same horizontal
plane. The first weight 11 to which the sliding
members 39 are installed moves smoothly relative to
20 the second weight 29 in the vertical direction. As a
result, the first weight 11 and the second weight 29
mo.v_es together in the same direction on the same
horizontal plane and the first weight 11 moves
relative to the second weight 29 in the vertical
25 direction.
[0068]
In each of the preferred embodiments described
above, the exemplary case where the first weight 11 is
formed into a rectangular column is described.
I I-074PCT
However, this is not limitative and the first weight
11 may be formed into any polygonal columns such as a
triangular column and a pentangular column. The first
weight 11 may be formed in a column or an elliptic
5 column as well. In such case, the frame 35, 44 is a
cylindrical member which has polygonal or cylindrical
shape formed along the outer periphery of the first
weight 11.
10 [Reference Signs list]
[0069]
1 Wind turbine generator
2 base
3 tower
15 4 nacelle
5 rotor
5A hub
5B blade
7, 27, 37, 47Vibration control apparatus
20 8 floor
8a upper floor
9 _opening
10 first vibration system
11 first weight
25 12 universal joint
13 supporting bar
14 weight piece
15 first container
16 second container
17 extension part
18 side panel
20, 26 second vibration system
21, 29 second weight
5 22 elastic member
23 connection member
24 rubber
25, 28 weight piece
25A, 25B weight piece
10 30, 33, 43, 45 restraining unit
31 guide
32 sliding part
34, 36 bolt
35, 44 frame
15 38, 39 sliding member
40 damper
41 bracket
46 groove
47 projection
20 48 third container
49 outer cylinder
50 -inner cylinder
51 weight piece
52 ladder
25 53A, 53B cable
100 coupling member

[CLAIMS]
1. A vibration control apparatus for a structure,
comprising:
a first vibration system which comprises a first
5 weight, a supporting bar installed upright on the
structure to support the first weight on the
structure, a lower universal joint connecting a
lower end of the support bar to the structure and
an upper universal joint connecting an upper end of
10 the support bar to the first weight;
a second vibration system which comprises an elastic
member installed upright on the structure and a
second weight arranged on the elastic member; and
a restraining unit which restrains the first weight
15 with respect to the second weight such that the
first and second weights move in the same direction
on the same horizontal plane and the first weight
moves relative to the second weight in a vertical
direction.
20
2. The vibration control apparatus according to claim
1,
wherein the restraining unit comprises:
a frame which surrounds the first weight; and
25 a plurality of sliding members which are provided
between an outer periphery of the first weight and
an inner periphery of the frame.
3. The vibration control apparatus according to claim
-37-
11-074PCT
1,
wherein at least one of the first and second weights
is formed by a plurality of weight pieces each of
which is detachable.
5
4. The vibration control apparatus according to claim
1,
wherein the structure is a wind turbine generator.
10 5. The vibration control apparatus according to claim
4,
wherein the vibration control apparatus is installed
in a tower of the wind turbine generator,
wherein a pair of the second vibration systems are
15 provided on both sides of the first vibration
system in a circumferential direction of the tower,
wherein a frame and a plurality of sliding members are
provided between the pair of the second vibration
systems, the frame being integrally formed with the
20 second weight to surround the first weight, each of
the sliding members being arranged between the
-first weight and the frame.
6. The vibration control apparatus according to claim
25 1,
wherein a weight ratio of the first weight to the
second weight is changed to adjust a oscillation
cycle of a main body of the vibration control
apparatus without changing a total weight of the
11-074PCT
first and second weights.
7. The vibration control apparatus according to claim
1, further comprising:
5 a damper one end of which is connected to the
structure and other end of which is connected to
one of the first and second weights.
8. The vibration control apparatus according to claim
10 7,
wherein the damper is arranged horizontally.
9. A wind turbine generator, comprising:
the vibration control apparatus of any one of claims 1
15 through 8.
10. The wind turbine generator according to claim 9,
wherein the vibration control apparatus is installed
on an upper floor of the tower of the wind turbine
20 generator.
ll._A vibration control method for a structure,
comprising the steps of:
installing upright a first vibration system comprising
25 a support bar and a first weight on the structure
by connecting one end of the support bar to the
structure, the supporting bar being connected to a
universal joint at both ends of the supporting bar,
the first weight being coupled to other end of the
11-074PCT
support bar via the universal joint;
installing upright a second vibration system
comprising an elastic member and a second weight on
the structure by connecting one end of the elastic
5 member to the structure, the second weight being
connected to other end of the elastic member;
restraining the first weight with respect to the
second weight by a restraining unit; and
when the structure shakes, oscillating the first and
10 second weights such that the first and second
weights move in the same direction on the same
plane and the first weight moves relative to the
second weight in a vertical direction.
15 12. The vibration control method according to claim 11,
wherein at least one of the first and second weights
is formed by a plurality of weight pieces each of
which. is detachable, and
wherein the vibration control method, comprises the
20 step of:
changing a number of the weight pieces of at least
one of the first and second weights to change a
weight ratio of the first weight to the second
weight