Patent Description:
For example, in a washing machine of <CIT>, a liquid balancer is attached to the washing tub in order to restrain vibrations of the washing tub.

In this liquid balancer, liquid is enclosed in an annular container, and a plurality of obstacle members are provided inside the container.

Because the liquid collides with the obstacle members when vibrations occur, a part of the kinetic energy of the liquid is converted to heat energy and the energy is dispersed, with the result that the vibrations are restrained.

<CIT> is related to a rotary damper with a breaking fluid interposed between a first component and a second component mounted rotatably in the first component. Moreover, a one way clutch is defined between the second and a third component.

<CIT> discloses a known liquid damper system for restraining vibrations occurring in a rotating body, comprising a liquid damper which is coaxially rotatable with the rotating body and includes a collision member, the collision member being provided in a casing in which liquid is enclosed, and the liquid colliding with the collision member when moving in the circumferential direction.

Strong vibrations typically occur when the rotation number of a rotating body becomes identical with the natural frequency of the rotating body (main resonance). In regard to vibrations occurring when the rotation number of a rotating body passes the main resonance frequency while the rotating body accelerates or decelerates or vibrations occurring when a rotating body steadily rotates at a rotation number different from the main resonance frequency, a liquid damper such as the liquid balancer of <CIT> is able to restrain such vibrations. However, when a rotating body steadily rotates at the main resonance frequency, the rotating body and the liquid in the liquid damper rotate together because the orbital revolution of the whirling rotating body is matched with the autorotation of the rotating body. When this is the case, the liquid is adhered to the inner wall surface of the liquid damper and becomes immovable on account of a centrifugal force, and the energy is not dispersed by the collision of the liquid. For this reason, the vibrations are not effectively restrained.

In consideration of this problem, an object of the present invention is to effectively restrain vibrations of a rotating body when the rotating body steadily rotates at a main resonance frequency, in a liquid damper system which is configured to restrain vibrations occurring in the rotating body.

A liquid damper system of the present invention, which is for restraining vibrations occurring in a rotating body, includes: a liquid damper which is coaxially rotatable with the rotating body and includes a collision member, the collision member being provided in a casing in which liquid is enclosed, and the liquid colliding with the collision member when moving in the circumferential direction; and a relative rotation unit configured to cause the liquid damper to rotate relative to the rotating body.

In the liquid damper system of the present invention, the liquid damper rotates relative to the rotating body on account of the relative rotation unit, in the same or opposite direction. For this reason, even when the rotating body steadily rotates at the main resonance frequency, the liquid in the liquid damper does not rotate together with the rotating body as the orbital revolution of the whirling rotating body is not matched with the autorotation of the rotating body, and hence the problem that the liquid is adhered to the inner wall surface of the liquid damper on account of a centrifugal force and becomes immovable is prevented. For this reason, because the liquid always collides with the collision members, a part of the kinetic energy of the liquid is converted to heat energy and the energy is dispersed, with the result that the vibrations of the rotating body are effectively restrained even when the rotating body steadily rotates at the main resonance frequency.

Preferably, as the relative rotation unit, an air resistance imparting member is provided to increase air resistance when the liquid damper rotates.

With this air resistance imparting member, rotational resistance is exerted to the liquid damper when the liquid damper rotates, with the result that the rotation speed of the liquid damper becomes lower than that of the rotating body. In this way, the liquid damper is arranged to rotate relative to the rotating body.

Preferably, the air resistance imparting member is a plate member having a surface intersecting with the rotational direction of the liquid damper.

When the plate members having a surface intersecting with the rotational direction of the liquid damper is used as the air resistance imparting member, the structure of the air resistance imparting member is simplified.

Preferably, the plate member is provided on an outer circumferential surface of the liquid damper.

Because the plate member is provided on the outer circumferential surface of the liquid damper, the distance between the acting position of the air resistance and the rotational center of the liquid damper is long, and hence the rotational resistance torque acting on the liquid damper is large. The rotation speed of the liquid damper is therefore efficiently decreased, and hence the liquid damper certainly rotates relative to the rotating body.

Preferably, the plate member is provided on an end face in the axial direction of the liquid damper.

This arrangement restrains increase in size of the liquid damper system in the radial direction, and the liquid damper system is downsized.

Preferably, the plate member is tilted toward downstream in the rotational direction as compared to the direction orthogonal to the outer circumferential surface of the liquid damper.

When the plate member is shaped in this manner, outward escape of air in the centrifugal direction along the plate member is restrained when the liquid damper rotates, and the air resistance exerted to the plate member is therefore increased.

In addition to the above, preferably, a fluid blowing unit configured to blow out fluid so that a hydrostatic pressure is exerted to the plate member in the direction opposite to the rotational direction is further provided.

With such a fluid blowing unit, the rotational resistance exerted to the plate members is increased, and hence the casing certainly rotates relative to the rotating body.

A brake mechanism including an electromagnetic effect target which is provided in the liquid damper and is a target of an electromagnetic effect and an electromagnetic effector which exerts the electromagnetic effect to the electromagnetic effect target may be provided as the relative rotation unit.

When the electromagnetic brake mechanism is employed as the relative rotation unit, a braking force is exerted to the liquid damper when the liquid damper rotates, with the result that the rotation speed of the liquid damper is arranged to be lower than that of the rotating body.

In this way, the liquid damper is arranged to rotate relative to the rotating body.

Specific structures of the electromagnetic effector and the electromagnetic effect target will be detailed later.

A gear mechanism may be provided as the relative rotation unit, the gear mechanism including gear portions formed on the outer circumferential surface of the liquid damper, a gear engaged with the gear portions, and a driving unit configured to generate a rotational torque in the liquid damper by rotating the gear.

As the rotational torque is generated in the liquid damper by driving the gear, the liquid damper is arranged to rotate relative to the rotating body.

Preferably, the driving unit is a variable speed motor in which the rotation speed of an output shaft is variable.

The rotation speed of the gear is therefore adjustable, and hence the rotation speed of the liquid damper is variable. On this account, the rotation speed of the liquid damper is adjustable in accordance with the state of vibration of the rotating body, and hence the degree of vibration suppression is further improved.

In the liquid damper system of the present invention, because the relative rotation unit which causes the liquid damper to rotate relative to the rotating body is provided, the liquid in the liquid damper does not rotate together with the rotating body, and the vibrations of the rotating body are effectively restrained even when the rotating body steadily rotates at the main resonance frequency.

The following will describe a liquid damper system of an embodiment of the present invention.

<FIG> is a cross sectional view of the liquid damper system of First Embodiment, showing a cross section taken along the axis of a rotating body <NUM>.

<FIG> is a cross sectional view of a cross section taken at the II-II line in <FIG>.

While the present embodiment assumes that the axial direction of the rotating body <NUM> is identical with the up-down direction, the axial direction of the rotating body <NUM> may be different from the up-down direction.

The liquid damper system <NUM> is a damper system including a liquid damper <NUM>.

In the liquid damper <NUM>, liquid <NUM> is enclosed in an internal space <NUM> which is formed in a casing <NUM>. The liquid damper <NUM> is attached to the rotating body <NUM> to be coaxially rotatable with the rotating body <NUM>.

While the liquid <NUM> in the present embodiment is water, the liquid <NUM> is not limited to water.

Before the liquid damper <NUM> is detailed, an attaching mechanism for attaching the liquid damper <NUM> to the rotating body <NUM> is described.

On the outer circumferential surface of the rotating body <NUM>, a cylindrical boss <NUM> is fixed. On the outer circumferential surface of the boss <NUM>, two bearings, i.e., upper and lower bearings <NUM> are fixed.

While each bearing <NUM> in the present embodiment is a ball bearing, each bearing <NUM> may not be a ball bearing.

At an upper portion of the outer circumferential surface of the boss <NUM>, a stepped portion 101a is formed.

The upper bearing <NUM> is externally fitted to the boss <NUM> while being in contact with this stepped portion 101a.

Below the upper bearing <NUM>, a first spacer <NUM>, the lower bearing <NUM>, a second spacer <NUM>, and an engaging member <NUM> are provided in this order and externally fitted to the boss <NUM>.

The engaging member <NUM> is, for example, a C-ring and is fitted into an annular groove 101b which is formed in the outer circumferential surface of the boss <NUM>.

Between the second spacer <NUM> and the engaging member <NUM>, a biasing member <NUM> which is formed of a disc spring, a corrugated washer, and the like is provided.

Because the two bearings <NUM> are biased toward the stepped portion 101a by this biasing member <NUM>, a suitable pre-load is applied to the bearings <NUM>.

On the inner side in the radial direction of each bearing <NUM>, an O-ring <NUM> is provided.

An inner race 102a of the bearing <NUM> is fixed to the boss <NUM>, whereas an outer race 102b of the bearing <NUM> is fixed to the casing <NUM> of the liquid damper <NUM>.

The liquid damper <NUM> rotates together with the rotating body <NUM> on account of frictions of the bearings <NUM>.

In this connection, in the present invention, the degree of vibration suppression is improved by arranging the liquid damper <NUM> to actively rotate relative to the rotating body <NUM> as described below.

The following will describe the structure of the liquid damper <NUM>.

The liquid damper <NUM> is basically structured such that the liquid <NUM> is enclosed in the internal space <NUM> of the casing <NUM>.

The casing <NUM> is mainly formed of a casing main body 11a and a lid member 11b.

The casing main body 11a is a hollow cylinder at the center of which a through hole is formed to allow the rotating body <NUM> to penetrate the same, and hence the annular internal space <NUM> is formed therein.

The internal space <NUM> is open at an upper part, and the lid member 11b is fixed to the upper surface of the casing main body 11a by a bolt or the like in order to close the opening.

As shown in <FIG>, on an inner wall surface 11c which is on the outer side in the centrifugal direction (outer side in the radial direction) of the casing <NUM>, plate-shaped collision members <NUM> are provided. These collision members <NUM> protrude from the inner wall surface 11c toward the internal space <NUM> so that the liquid may collide with them when moving in the circumferential direction.

Eight collision members <NUM> are provided in total at equal intervals in the circumferential direction. The angle between neighboring collision members <NUM> is <NUM> degrees.

The number and disposition of the collision members <NUM> are not limited to this and may be suitably altered.

On the outer circumferential surface of the liquid damper <NUM> (casing <NUM>), plate members <NUM> are provided to protrude outward in the centrifugal direction. Each plate member <NUM> has a surface intersecting with the rotational direction of the liquid damper <NUM>.

Eight plate members <NUM> are provided in total at equal intervals in the circumferential direction. The angle between neighboring plate members <NUM> is <NUM> degrees.

The number and disposition of the plate members <NUM> are not limited to this and may be suitably altered.

The following will describe how the liquid damper system <NUM> structured as above operates.

When the rotating body <NUM> is rotationally driven by an unillustrated driving unit, the liquid damper <NUM> is passively driven on account of the frictions of the bearings <NUM>.

As the liquid damper <NUM> rotates, air resistance is exerted to the plate members <NUM>, with the result that rotational resistance is generated against the liquid damper <NUM>.

The rotational resistance increases as the rotation speed of the liquid damper <NUM> increases. When the rotational resistance becomes larger than the friction forces of the bearings <NUM>, the rotation speed of the liquid damper <NUM> starts to delay from that of the rotating body <NUM>.

As a result, the casing <NUM> rotates relative to the rotating body <NUM>.

In the liquid damper system <NUM> of the present embodiment, the liquid damper <NUM> rotates relative to the rotating body on account of a relative rotation unit formed of the plate members <NUM>.

For this reason, even when the rotating body <NUM> steadily rotates at the main resonance frequency, the liquid <NUM> in the liquid damper <NUM> does not rotate together with the rotating body <NUM>, and hence the problem that the liquid <NUM> is adhered to the inner wall surface 11c of the liquid damper <NUM> on account of a centrifugal force and becomes immovable is prevented. For this reason, because the liquid <NUM> always collides with the collision members <NUM>, a part of the kinetic energy of the liquid <NUM> is converted to heat energy and the energy is dispersed, with the result that the vibrations of the rotating body <NUM> are effectively restrained even when the rotating body <NUM> steadily rotates at the main resonance frequency.

An experiment was done to verify the vibration suppression for the rotating body <NUM> by the liquid damper system <NUM>.

The verification experiment was done in the following three cases: the liquid damper <NUM> was not attached to the rotating body <NUM>; the liquid damper <NUM> was attached to the rotating body <NUM> and the rotation number of the liquid damper <NUM> was arranged to be identical with (in sync with) the rotation number of the rotating body <NUM>; and the liquid damper <NUM> was attached to the rotating body <NUM> and the rotation number of the liquid damper <NUM> was arranged to be different from (out of sync with) that of the rotating body <NUM>.

In each case, the rotation number of the rotating body <NUM> was increased at predetermined intervals, and a vibration frequency of the rotating body <NUM> was measured when steady rotation was achieved at each rotation number.

In the cases where the liquid damper <NUM> was provided, the liquid damper <NUM> was arranged to be in sync with the rotating body <NUM> as the plate members <NUM> were not attached, whereas the liquid damper <NUM> was arranged to be out of sync with the rotating body <NUM> as the plate members <NUM> were attached.

<FIG> is a graph showing results of the verification experiment.

When the liquid damper <NUM> was not used, large main resonance occurred when the rotation number of the rotating body <NUM> was 1350rpm.

When the liquid damper <NUM> was attached to the rotating body <NUM> (but the plate members <NUM> were not provided) and the liquid damper <NUM> was arranged to be in sync with the rotating body <NUM>, the main resonance was not decreased but increased as compared to the case where the liquid damper <NUM> was not attached. This is presumably because, when the rotation number of the liquid damper <NUM> is identical with that of the rotating body <NUM>, the rotating body <NUM> and the liquid <NUM> in the liquid damper <NUM> rotate together, with the result that collision of the liquid <NUM> with the collision members <NUM> does not occur and hence energy dispersion does not occur.

Meanwhile, when the liquid damper <NUM> and the plate members <NUM> were attached and the liquid damper <NUM> was arranged to be out of sync with the rotating body <NUM>, the main resonance was hardly noticeable, indicating that the vibrations of the rotating body <NUM> were restrained in a wide range of rotation numbers. In the experiment, the percentage of water as the liquid <NUM> relative to the capacity of the internal space <NUM> was about <NUM>%. This proves that a significantly high degree of vibration suppression is achieved even when the amount of the liquid <NUM> is small.

This is presumably because the weight of the liquid <NUM> is apparently increased by a centrifugal force and hence the energy of the collision is increased.

By the way, when the liquid damper <NUM> rotates, a centrifugal force is exerted to the liquid <NUM> in the liquid damper <NUM>, with the result that the liquid <NUM> is adhered to the inner wall surface 11c on the outer side in the centrifugal direction. In this regard, when the collision members <NUM> are provided to protrude from the inner wall surface 11c toward the internal space <NUM> as in the present embodiment, it is possible to prevent the liquid <NUM> adhered to the inner wall surface 11c from rotating en masse. Energy is therefore dispersed because the collision of the liquid <NUM> occurs even in the steady state.

In addition to the above, in the present embodiment, air resistance imparting members (plate members <NUM>) are provided as a relative rotation unit to increase the air resistance during the rotation of the liquid damper <NUM>. On this account, rotational resistance is imparted to the liquid damper <NUM> when the liquid damper <NUM> rotates, with the result that the rotation speed of the liquid damper <NUM> becomes lower than that of the rotating body <NUM>.

In this way, the liquid damper <NUM> is arranged to rotate relative to the rotating body <NUM>.

In addition to the above, because the air resistance imparting members of the present embodiment are the plate members <NUM> each having a surface intersecting with the rotational direction of the liquid damper <NUM>, the structure of each air resistance imparting member is simple.

In addition to the above, because in the present embodiment the plate members <NUM> are provided on the outer circumferential surface of the liquid damper <NUM>, the distance between the acting position of the air resistance and the rotational center of the liquid damper <NUM> is long, and hence the rotational resistance torque acting on the liquid damper <NUM> is large. The rotation speed of the liquid damper <NUM> is therefore efficiently decreased, and hence the liquid damper <NUM> certainly rotates relative to the rotating body <NUM>.

<FIG> is a top view showing Modification <NUM> of First Embodiment. In this modification, each plate member <NUM> is not along the radial direction but is shaped such that the plate member <NUM> is tilted toward the downstream in the rotational direction as compared to the direction orthogonal to the outer circumferential surface of the liquid damper <NUM>.

With such plate members <NUM>, when the liquid damper <NUM> rotates, radially outward escape of air along each plate member <NUM> is restrained and capture of air in the space between each plate member <NUM> and the liquid damper <NUM> is facilitated, as indicated by the outlined arrow in <FIG>. The air resistance exerted to each plate member <NUM> is therefore increased.

<FIG> is a top view showing Modification <NUM> of First Embodiment. The shape of each plate member <NUM> and the like in this modification are identical with those shown in <FIG>, but fluid blowing units <NUM> are additionally provided.

The fluid blowing units <NUM> are provided around the liquid damper <NUM> and each blows out fluid such as air through an outlet 24a. Because each outlet 24a is provided to face in the direction substantially opposite to the rotational direction of the liquid damper <NUM>, the fluid blowing units <NUM> exert hydrostatic pressures to the plate members <NUM> in the direction opposite to the rotational direction of the liquid damper <NUM>.

The rotational resistance exerted to the plate members <NUM> is therefore increased, and hence the liquid damper <NUM> certainly rotates relative to the rotating body <NUM>.

It is noted that the number and disposition of the fluid blowing units <NUM> are not limited to those shown in <FIG>, and may be suitably altered.

<FIG> is a top view showing a liquid damper system of Second Embodiment.

In a liquid damper system <NUM> of this embodiment, an electromagnetic brake mechanism <NUM> is provided as a relative rotation unit by which the liquid damper <NUM> is rotated relative to the rotating body <NUM>.

This brake mechanism <NUM> includes a conductor <NUM> (electromagnetic effect target) provided on the outer circumferential surface of the liquid damper <NUM> (casing <NUM>), a coil <NUM> (electromagnetic effector) provided to be apart from the outer circumferential surface of the liquid damper <NUM>, and a current controller <NUM> controlling a current supplied to the coil <NUM>.

It is noted that the numbers and dispositions of the conductor <NUM> and the coil <NUM> are not limited to those shown in <FIG>, and may be suitably altered.

For example, a plurality of coils <NUM> may be provided along the circumferential direction at regular intervals.

When a current is supplied to the coil <NUM> by the current controller <NUM>, a magnetic force generated between a magnetic flux formed around the coil <NUM> by electromagnetic induction and a magnetic flux formed due to an eddy current generated in the conductor <NUM> of the liquid damper <NUM> functions as a braking force.

To put it differently, when the liquid damper <NUM> rotates, a braking force is exerted to the liquid damper <NUM> by the brake mechanism <NUM>, with the result that the rotation speed of the liquid damper <NUM> is arranged to be lower than that of the rotating body <NUM>.

According to the present embodiment, the magnitude of a magnetic field generated around the coil <NUM> is changeable by adjusting the current supplied to the coil <NUM> by the current controller <NUM>, and hence the braking force generated between the conductor <NUM> and the coil <NUM> is changeable.

The rotation speed of the liquid damper <NUM> is therefore adjustable in accordance with the state of vibrations of the rotating body <NUM>, and hence the degree of vibration suppression is further improved.

Furthermore, a larger braking force is obtained when the conductor <NUM> is constituted by a magnetic body, because a larger eddy current is generatable.

In the present embodiment, the electromagnetic effector <NUM> may be a permanent magnet instead of a coil.

The current controller <NUM> can be omitted in this case, and hence the relative rotation unit is relatively easily constructed.

According to a modification of the present embodiment, the electromagnetic effect target <NUM> provided on the outer circumferential surface of the liquid damper <NUM> may be a permanent magnet.

In this modification, a large braking torque is generatable by suitably controlling the frequency of an alternating current supplied to the coil <NUM> by the current controller <NUM> connected to the coil <NUM>.

<FIG> is a top view showing a liquid damper system of Third Embodiment.

In a liquid damper system <NUM> of this embodiment, a gear mechanism <NUM> is provided as a relative rotation unit by which the liquid damper <NUM> is rotated relative to the rotating body <NUM>. This gear mechanism <NUM> includes gear portions 11d formed on the outer circumferential surface of the liquid damper <NUM> (casing <NUM>), a gear <NUM> engaged with the gear portions 11d, a rotational shaft <NUM> connected to the gear <NUM> and substantially in parallel to the rotating body <NUM>, and a motor <NUM> (driving unit) having an unillustrated output shaft connected to the rotational shaft <NUM> and configured to rotationally drive the rotational shaft <NUM>.

A housing (not illustrated) of the motor <NUM> is, for example, attached to the rotating body <NUM> via a bearing which is substantially without friction, and the housing is provided so that the position of the motor <NUM> is not varied when the rotating body <NUM> and/or the liquid damper <NUM> rotates.

When the liquid damper <NUM> rotates, the gear <NUM> also rotates in the direction shown in <FIG>.

At this stage, when the motor <NUM> is driven at a frequency lower than the rotational frequency of the gear <NUM> which is in sync with the rotation of the liquid damper <NUM>, the motor <NUM> functions as a brake.

On this account, a rotational resistance is exerted to the liquid damper <NUM> which rotates on account of the rotation of the rotating body <NUM>, with the result that the rotation speed of the liquid damper <NUM> becomes lower than that of the rotating body <NUM>.

In this embodiment, the motor <NUM> is preferably a variable speed motor in which the rotation speed of the output shaft is variable.

The rotation speed of the gear <NUM> is therefore adjustable, and hence the rotation speed of the liquid damper <NUM> is variable. On this account, the rotation speed of the liquid damper <NUM> is adjustable in accordance with the state of vibration of the rotating body <NUM>, and hence the degree of vibration suppression is further improved.

Although the embodiments of the present invention have been described, the present invention is not limited to the above and can be suitably changed within the scope of the present invention (defined in the appended claims) as described below.

For example, according to the embodiments above, the collision members <NUM> protrude from the inner wall surface 11c which is on the outer side in the centrifugal direction of the casing <NUM> toward the internal space <NUM>.

Alternatively, the collision members <NUM> may protrude toward the internal space <NUM> from the inner wall surface on the inner side in the centrifugal direction of the casing <NUM>, or may protrude toward the internal space <NUM> from the ceiling or the bottom surface of the casing <NUM>.

Alternatively, each collision member <NUM> may be a plate-shaped member which is provided to bridge the gap between the inner wall surface on the inner side in the centrifugal direction and the inner wall surface on the outer side in the centrifugal direction and has an opening or a notch which penetrates the plate-shaped member in the circumferential direction. Alternatively, each collision member <NUM> may not be plate-shaped and may be column-shaped or block-shaped. Furthermore, each collision member <NUM> may be an uneven portion or a corrugated portion formed on a side or bottom surface of the casing <NUM>.

In the embodiments above, the internal space <NUM> of the casing <NUM> is a single chamber.

Alternatively, a partition wall may be provided in the internal space <NUM> along the circumferential direction to divide the internal space <NUM> into plural spaces in the radial direction. In such a case, a collision member <NUM> is provided in each of these spaces formed by the division.

While in First Embodiment the plate members <NUM> to <NUM> are provided on the outer circumferential surface of the liquid damper <NUM> (casing <NUM>), the plate members <NUM> to <NUM> may be formed on an end face (an upper surface or a lower surface) in the axial direction of the liquid damper <NUM> (casing <NUM>), in addition to or instead of the outer circumferential surface.

For example, in a modification shown in <FIG>, plate members <NUM> are provided on an upper surface 11e of a liquid damper <NUM> (casing <NUM>). In this regard, in addition to or instead of the upper surface 11e, plate members <NUM> may be provided on a lower surface.

This arrangement restrains increase in size of the liquid damper system <NUM> in the radial direction, and the liquid damper system <NUM> is downsized.

In Second Embodiment, the conductor <NUM> is provided in the liquid damper <NUM> as an electromagnetic effect target and the coil <NUM> is provided around the liquid damper <NUM> as an electromagnetic effector. Alternatively, a coil may be provided in the liquid damper <NUM> as an electromagnetic effect target whereas a permanent magnet may be provided around the liquid damper <NUM> as an electromagnetic effector.

In this case, the rotation speed of the liquid damper <NUM> is adjustable by changing the distance to the liquid damper <NUM> by moving the permanent magnet.

While in First to Third Embodiments the rotation speed of the liquid damper <NUM> is lower than that of the rotating body <NUM>, a difference in relative speed may be achieved by arranging the rotation speed of the liquid damper <NUM> to be higher than that of the rotating body <NUM>.

For example, the direction of the fluid blowing unit <NUM> in Modification <NUM> of First Embodiment (see <FIG>) may be changed to exert a hydrostatic pressure in the rotational direction of the liquid damper <NUM>.

Alternatively, in Third Embodiment (see <FIG>), the rotation speed of the liquid damper <NUM> may be arranged to be higher than that of the rotating body <NUM>, by means of the motor <NUM>.

In addition to the above, the rotational direction of the liquid damper <NUM> may be arranged to be opposite to the rotational direction of the rotating body <NUM>.

Claim 1:
A liquid damper system (<NUM>) for restraining vibrations occurring in a rotating body (<NUM>), comprising:
a liquid damper (<NUM>) which is coaxially rotatable with the rotating body (<NUM>) and includes a collision member (<NUM>), the collision member (<NUM>) being provided in a casing (<NUM>) in which liquid (<NUM>) is enclosed, and the liquid (<NUM>) colliding with the collision member (<NUM>) when moving in the circumferential direction; and
a relative rotation unit (<NUM> to <NUM>, <NUM>, <NUM>, <NUM>) configured to cause the liquid damper (<NUM>) to rotate relative to the rotating body (<NUM>).