JPH10169699A - Liquid filled bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid-sealed bush whereby a vibration damping characteristic in a low frequency particularly in the vicinity of 10Hz can be enhanced while enlargement in size of a main unit part is suppressed. SOLUTION: A spool 19 having a U-shaped orifice path 23 such as reciprocated along an axial direction in a peripheral surface is fit inserted rotatably to a shaft-shaped member 11 provided in the center of a liquid-sealed bush 5, by turning the spool 19, a passage end of the U-shaped orifice path 23 is connected/disconnected relating to a pair of fluid chambers 16a, 16b formed in an elastic unit part in both sides interposing the shaft-shaped member 11, in the orifice path 23 of long passage length as made difficult, so as to generate damping force causing vibration isolation in a low frequency band particularly in the vicinity of 10Hz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-filled bush whose vibration isolation characteristics can be switched according to vibration.

[0002]

2. Description of the Related Art In a vehicle suspension device, a rubber (elastic body) bush is interposed between a pivot portion of an arm and a vehicle body constituting the suspension device to absorb vibration of a front wheel applied from the arm. Has been done. Specifically, a cylindrical elastic body is interposed between a shaft member serving as a support member for the arm and the vehicle body and a cylindrical outer cylinder member on the outer peripheral side thereof, and vibration of the front wheel transmitted from the arm is transmitted. So that it absorbs.

[0003] By the way, from a suspension in a low frequency range that causes shimmy vibrations (running of the front wheels while the vehicle is running) depending on the running state, a shock when the front wheels cross over a small unevenness of the road surface from the vehicle body due to harshness. Vibration transmitted in the high frequency range.

However, since the rubber bush has a structure in which the vibration isolation performance is determined by the spring constant of the rubber member, the rubber bushing has a vibration isolation characteristic corresponding to any of a low frequency range, a high frequency range, and a frequency range intermediate between them. Forced to do so.
Therefore, the anti-vibration performance is not sufficient.

Therefore, as disclosed in Japanese Patent Laid-Open Publication No. Sho 63-176843, a liquid is sealed in an elastic portion sandwiching a shaft member as a bush which can provide vibration isolation characteristics in another frequency range. There has been proposed a liquid-filled bush having a structure in which a pair of fluid chambers is provided, and the pair of fluid chambers is communicated or blocked via an orifice passage.

[0006] Such a liquid-filled bush is switched so that the orifice road end communicates with the fluid chamber.
Utilizing the relative displacement between the shaft member and the outer cylinder member caused by the vibration, the liquid passes through the orifice passage, and has a function of damping the vibration with the damping force generated at that time. I have. By damping this vibration, the dynamic spring constant of the bush is reduced, and the setting of the frequency range of the vibration-proof characteristic is being broadened.

[0007]

By the way, a bush which generates a damping force due to the flow of a liquid, has a low frequency (10 Hz).
In order to obtain the vibration damping characteristics in the vicinity, it is necessary to secure the length of the flow path of the orifice path to about the square of the set frequency ratio when the flow path cross-sectional area is constant.

However, since the liquid-filled bush itself is used in a restricted support structure, the outer shape of the main body cannot be increased, and the length of the flow path of the orifice passage is reduced in the low frequency range. It is difficult to make it longer to correspond to.

Therefore, in Japanese Patent Laid-Open Publication No. Sho 63-176843, the length of the flow path is increased by using an arc-shaped orifice path which follows the outer peripheral surface of the shaft member. However, even this flow path length is insufficient to obtain vibration isolation characteristics in a low frequency range around 10 Hz.

[0010] To reduce the cross-sectional area of the orifice passage as much as possible, it is not possible to secure a sufficient passage length. On the other hand, if the cross-sectional area of the flow path is too small, the flow of the liquid is impaired, and it becomes impossible to switch the characteristics of absorbing vibration.

[0011] For this reason, it is difficult to secure the vibration isolation characteristics in the low frequency range around 10 Hz, and there is a demand for a liquid-filled bush that is effective in improving the vibration isolation characteristics in the low frequency range.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid-filled bush that can improve the vibration isolation characteristics at low frequencies, particularly around 10 Hz, while suppressing the size of the main body. Is to provide.

[0012]

In order to achieve the above object, the invention described in claim 1 provides a first support member having a shaft shape and a second cylindrical member arranged on the outer peripheral side of the support member. A main body configured by providing an elastic body between the support member, a pair of fluid chambers formed in an elastic body portion sandwiching the first support member and sealing a fluid, and a shaft of the first support member An orifice path formed along the center direction and having both ends connected to each of the pair of fluid chambers, and a flow path switching means for selectively communicating and blocking the pair of fluid chambers or the orifice path and the pair of fluid chambers. The liquid-filled bush.

According to the first aspect of the present invention, the liquid-filled bush can easily secure an orifice passage having a long passage length by utilizing the existing axial length of the first support member.

This makes it possible to set an orifice path that provides vibration isolation characteristics in a low frequency range. As a result, the liquid in the fluid chamber flows through the orifice passage having a considerably long passage length, so that the liquid-filled bush generates a damping action having excellent vibration isolation characteristics in a low frequency range.

Accordingly, the liquid-filled bush has improved vibration-proof characteristics in a low frequency range. Effective vibration damping performance is provided in a low frequency range around 10 Hz. In addition, since the orifice passage is provided in the existing first support member, the main body of the liquid-filled bush does not need to be large.

According to a second aspect of the present invention, in addition to the above object, in order to enable the orifice path to be switched with a simple structure, the flow path switching means according to the first aspect is provided with an orifice path on the outer peripheral surface. Is formed, and a shaft-shaped rotating member inserted rotatably around the axis of the first supporting member inside the first supporting member; and an orifice path end provided in the first supporting member and the fluid chamber. The present invention is configured to include a doorway for communication and a driving means for rotating and displacing the rotating member.

According to a third aspect of the present invention, in addition to the above objects, a plurality of types of anti-vibration characteristics can be set at once, and various anti-vibration characteristics can be changed by changing a rotating member. The rotating member according to claim 2 is configured to have an orifice hole penetrating in a diametrical direction at a portion different from the orifice passage, and further, the driving means communicates / blocks the orifice passage and the orifice hole with a pair of fluid chambers. In the motor.

According to a fourth aspect of the present invention, in addition to the above object, in order to secure various vibration damping performances suitable for a running state required of a vehicle suspension device, the motor according to the third aspect is provided by using the vehicle according to the third aspect. In accordance with the traveling state of the orifice, the control means controls the communication between the orifice passage and the orifice hole.

According to a fifth aspect of the present invention, in addition to the above object, an improvement in steering stability when the damping characteristic is made hard,
In order to improve the ride comfort when soft, and to reduce the shimmy vibration and improve the straight running stability by setting the damping characteristic to a medium state at high speed straight ahead, the shaft-shaped first support member and this support A body is formed by providing an elastic body between a cylindrical second support member disposed on the outer peripheral side of the member and an elastic body portion sandwiching the first support member, and a fluid is sealed therein. And a fluid enclosing bush having a pair of fluid chambers which can communicate and shut off the pair of fluid chambers so that the damping characteristic can be varied hardly and softly, further along the axial direction of the first support member. An orifice passage having both ends connected to each of the pair of fluid chambers, and selectively communicating the orifice passage with the pair of fluid chambers.
It is to cut off and attenuate shimmy vibration in a low frequency range.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS. FIG. 1 shows a front suspension device for an automobile (vehicle) to which the present invention is applied. In the figure, reference numeral 1 denotes a strut-type suspension assembly supported on, for example, a vehicle body (not shown).

The suspension assembly 1 has a shock absorber 1a whose upper end is supported by the vehicle body and extends downward from the vehicle body, and a coil spring 1b integrated with the shock absorber 1a.

A knuckle arm 3 for supporting the front wheel 2 is fixed to the lower end of the shock absorber 1a. A lower arm, for example, a lower arm assembly 4 formed by combining a vehicle front side lateral arm 4a and a vehicle rear side compression arm 4b into an A shape projects from a vehicle body (not shown). It is pivotally supported in the vehicle width direction.

Each base end of the lateral arm 4a and the compression arm 4b is pivotally supported on the vehicle body so as to be vertically rotatable with respect to the vehicle body.
In addition, the front wheel 2 is suspended so as to be vertically displaceable.

A liquid-filled bush 5 is interposed at a pivot 4c at the base end of the compression arm 4b, which constitutes the lower arm assembly 4, for example, to absorb vibration transmitted from the front wheel 2.

An enlarged view in FIG. 1 shows an outer shape around the liquid sealing bush 5. FIG. 2 shows the structure around the liquid-filled bush 5. Here, a structure around the liquid sealing bush 5 which is a main part of the present invention will be described. In FIG. 1 and FIG.

The main body 10 has a shaft-like member 11 (corresponding to a first support member) having a bottomed tubular shape and a predetermined length, and a short tubular shape disposed on the outer peripheral side of the shaft-like member 11. Outer tube member 12
(Corresponding to a second support member) and a short cylindrical elastic body 13 (for example, made of an elastic member such as a rubber member) interposed between the shaft member 11 and the outer cylindrical member 12. It is configured.

The seat member 14a having a rectangular flange shape, for example, provided on the outer periphery of the opening end of the shaft member 11 and the flat seat portion 14b formed at the bottom end of the shaft member 11 are provided. Each is fixed to a body member, for example, a cross member (not shown) by bolts 15.

The outer cylinder member 12 is rotatably fitted in an eyeball 4d formed at the base end of the compression arm 4b, and rotatably supports the base end of the compression arm 4b on the vehicle body. Let me.

A pair of fluid chambers 16a and 16b are provided inside the elastic body 13 which is 180 ° out of phase with respect to the shaft member 11 so as to expose a pair of entrances and exits 13a provided on the peripheral wall of the shaft member 11. Is formed. Each of the fluid chambers 16a and 16b has a fan shape that expands in the circumferential direction, and contains a fluid, for example, a liquid 1 such as silicone.
7 is enclosed.

A bottomed sealing member 18 is removably fitted to the end of the inner cavity of the shaft member 11 having a larger diameter than the other portions. The lumen is sealed.

In a cylindrical bore formed by each peripheral wall of the seal member 18 and the shaft member 11, a shaft-shaped spool 19 (corresponding to a rotary member) corresponding to the shape of the bore is rotatable. It is inserted in. A chamfered portion 19a (inclined surface) is provided at a corner of the spool 19 on the seal member 18 side.
Is given.

At the end of the spool 19 corresponding to the entrances 13a, 13a, an orifice hole 20 formed by a through-hole penetrating in the diameter direction as shown in FIGS.
Are drilled.

As shown in FIGS. 4 and 5, a pair of long grooves 21a and 21b extending in the axial direction are formed on the outer peripheral surface of the spool portion which is shifted from the opening end of the orifice hole 20 by a predetermined angle in the circumferential direction. Are formed.

Each of the long grooves 21a and 21b is formed between the entrances and exits 13a and 13a and the chamfered portion 19a. The long grooves 21a and 21b communicate with each other via an annular space 22 formed between the chamfered portion 19a and the end face of the seal member 18, and the shaft-like member 1
A U-shaped orifice passage 23 is formed in the inside 1 so as to face in the axial direction. Each of the long grooves 21 a and 21 b has a passage cross-sectional area in a range that does not hinder the flow of the liquid 17.

The orifice passage 23 which reciprocates the existing shaft-like member 11 along the axial direction secures a passage length required for vibration-proof characteristics in a low frequency range. A small-diameter connecting rod 19b protruding from the center of the end on the base side of the spool 19 penetrates the bottom of the seal member 18, and is a rotary drive source detachably fixed to the end face of the seat member 14a, for example, a stepping motor. The spool 19 is detachably connected to the output shaft of the motor 24, and rotates the spool 19 by the rotational force transmitted from the step motor 24.

Then, the spool 19 is moved by the step motor 24 to the entrance 1 as shown in FIG.
3a, 13a and the orifice passage 20 communicate with each other, the entrances 13a and 13a as shown in FIG. 4 communicate with the long grooves 21a and 21b, and the entrances 13a and 13b and the orifices as shown in FIG. Road 20
And neither the long holes 21a and 21b communicate with each other, that is, the position c for shutting off the fluid chambers 16a and 16b.
Is positioned at

That is, the spool 19 and the step motor 2
In the switching mechanism 25 constituted by 4 and 4, the state where the fluid chambers 16a and 16b that provide a static spring constant of the rubber member is cut off is changed to the orifice path 20 having a long passage length that provides vibration isolation characteristics in a low frequency range. The orifice passage 20 having a short passage length for switching to a state in which the fluid chambers 16a and 16b communicate with each other or providing vibration isolation characteristics in another frequency range, that is, a high frequency range.
To switch to a state in which the fluid chambers 16a and 16b are communicated with each other (switching means).

Further, as shown in FIG. 1, the step motor 24 is an EC which comprises a microcomputer, for example.
It is connected to U26 (corresponding to control means). ECU26
Include a vehicle speed sensor 27 (sensor for detecting the vehicle speed) of a vehicle as a sensor for detecting the running state of the vehicle,
A handle angle sensor 28 (a sensor that detects the angle of the handle), a road surface sensor 29 (a sensor that detects unevenness of the road surface), and a lateral G sensor 30 (a sensor that detects a lateral G generated on the vehicle body) are connected.

The ECU 26 also has a map (not shown) for determining the stiffness value of the bush according to the running state of the vehicle, for example, under the conditions of vehicle speed, steering wheel angle, rough road, moderate to sharp steering.
In addition, a function of controlling the communication between the orifice hole 20 and the orifice path 23 according to these maps is set, so that the optimum vibration damping characteristics are exhibited according to the running state of the automobile.

That is, now, for example, a car
Suppose you are traveling straight at high speed. At this time, the ECU 26
Receives the detection signals from the various sensors 27, 28, 29, and 30, determines that the vehicle is traveling straight on a flat road surface at high speed from the vehicle speed, the steering wheel state, the road surface, and the lateral G state, and follows the map. Then, the rigidity value of the bush is set to, for example, an intermediate value (medium).

Next, the ECU 26 operates (rotates) the step motor 24 in accordance with the setting, and positions the spool 19 at the position b (medium) as shown in FIG.

Thus, the end of each of the long grooves 21a and 21b, that is, the U-shaped orifice passage 23 formed inside the shaft member 9 is connected to each of the fluid chambers 16a and 16b through the ports 13a and 13a. Communicate.

Here, as shown in FIG. 5 (c), the U-shaped orifice passage 23 uses the axial length of the shaft member 11 to extend from the entrances and exits 13a, 13a to the end of the shaft member 11. Since it is formed so as to reciprocate to the part, a considerably long passage length is ensured.

That is, the fluid chambers 16a and 16b are communicated with each other by the orifice passage 23 having a passage length corresponding to the vibration isolation characteristics in a low frequency range. This means that a typical low frequency range vibration, for example, shimmy vibration (lateral vibration of the front wheel 2 during traveling) is applied from the compression arm 4b during the traveling.

Then, a relative displacement occurs between the shaft-like member 11 and the outer cylindrical member 12, and the liquid 17 in the fluid chambers 16a and 16b flows through the orifice passage 23. Then, when the liquid 17 passes through the orifice passage 23, a damping force suitable for suppressing shimmy vibration is generated, and the straight running stability of the vehicle is improved.

According to the experiment, the U-shaped orifice passage 23 is used as shown by the broken line in the diagram representing the "dynamic characteristics of the liquid sealing bush" in FIG. 6 (state in FIG. 4).
It was confirmed that a damping force was generated that effectively attenuated the low frequency range where shimmy vibration was observed. In particular, vibration-proof performance effective for vibration in a low frequency range around 10 Hz was obtained. The thick line in FIG. 6 shows the characteristics when the orifice path 20 is open (the state shown in FIG. 2), and the thin line in FIG. 6 shows the characteristics when the orifice path 20 is closed (the state shown in FIG. 3).

When the vehicle is steered suddenly during traveling, the ECU 26
Determines the rapid steering based on the detection signal from the lateral G sensor 30, and sets the rigidity value of the bush to, for example, hard according to the map.

Then, the ECU 26 operates (rotates) the step motor 24 in accordance with the setting, and positions the spool 19 at the position c (hard) as shown in FIG.

As a result, as shown in FIG. 3 and FIG. 5B, the fluid chambers 16a and 16b are shut off, and the liquid sealing bush 5 has a static spring constant provided by the elastic body itself.
To maintain high rigidity and ensure steering stability.

During traveling, when the road surface sensor 29 detects a small protrusion on the road surface and the ECU 26 determines that a harshness is to be provided, the step motor 23 is operated (rotated), and for a moment, FIGS. The spool 19 is positioned at the position a (soft) as shown in FIG.

That is, the orifice hole 20 is
The fluid chambers 16a and 16b communicate with the fluid chambers 16a and 16b via the a and 13a. Here, since the orifice hole 20 is formed to be short by using the length in the diameter direction of the shaft-shaped member 11, a passage length corresponding to the vibration isolation characteristics in a high frequency range is provided between the fluid chambers 16a and 16b. It is communicated with the orifice road.

Then, the liquid 1 between the fluid chambers 16a and 16b
7 is easy to flow, and the vibration in the high frequency range generated when the front wheel 2 gets over the small protrusion is reduced. This allows
The harshness is attenuated to ensure a good ride.

According to the experiment, by using the orifice hole 20 having a short passage length as shown by the solid line in the diagram showing the "dynamic characteristics of the liquid sealing bush" in FIG. It was confirmed that a damping force for effectively damping was generated.

According to the liquid sealing bush 5 having the structure in which the U-shaped orifice passage 23 is formed in the shaft member 11 in the axial direction, excellent vibration damping characteristics in a low frequency range can be obtained. is there. Of course, since the orifice passage 23 is provided using the shaft-like member 11 used as a support member, the main body 10 does not need to be large.

Further, the orifice passage 23 is switched by a structure in which a spool 19 having long grooves 21a and 21b on its outer peripheral surface is rotatably fitted into the shaft member 11, and the spool 19 is driven to rotate by a step motor 24. Simple in structure. In particular, since the occupied space occupied by the driving portion is small, it is suitable for a suspension device in which various restrictions are placed on the periphery of the bush, which imposes restrictions on installation.

In addition, the spool 19 is provided with not only an orifice passage 23 effective for vibration damping in a low frequency band but also an orifice hole 20 having a short passage length effective for vibration damping in a high frequency band. Since the damping force for providing the vibration-proof characteristics is generated, a plurality of types of the vibration-proof characteristics can be set at once with one liquid-filled bush 5.

The use of the spool 19 allows the orifice passage 2 having different passage lengths to be set without changing the main body 10.
3. If the spool 19 is replaced with the spool 19 having the orifice hole 20, there is an advantage that various anti-vibration characteristics can be obtained. In addition, since the main body 10 is shared, it can be easily diverted between different types of automobiles.

Further, since the spool 19 is switched in accordance with the running condition of the vehicle, the anti-vibration performance suitable for the running condition required of the vehicle suspension device, for example, compatibility between the steering stability performance and the riding comfort performance is achieved. Three levels of anti-vibration performance can be obtained: soft, medium, and soft. In other words, while improving the steering stability when the damping characteristic is hard and improving the riding comfort when the damping characteristic is soft, the damping characteristic is set to a medium state at high speed straight ahead, reducing shimmy vibration and improving straight running stability. I can plan.

Although one embodiment adopts a structure in which the spool is rotated in the circumferential direction to switch the flow path, a structure in which the spool is slid in the axial direction to switch the flow path may be employed.

Further, in one embodiment, an example was given in which the liquid-filled bush was provided at the pivot portion of the arm of the suspension device. However, the present invention is not limited to this. For example, the bush used for mounting equipment, such as an engine, where vibration easily occurs. May be applied.

[0061]

As described above, according to the first aspect of the present invention, by utilizing the axial length of the first support member,
An orifice passage having a long passage length can be easily secured. Therefore, an orifice passage having a long passage length that provides vibration isolation characteristics in a low frequency range can be set in the liquid-filled bush.

Accordingly, it is possible to provide a liquid-filled bush having excellent vibration-proof characteristics in a low frequency range, which has been considered difficult, particularly in a low frequency range near 10 Hz. Moreover, since the U-shaped orifice passage is formed in the existing first support member, the main body of the liquid sealing bush does not need to be large.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention, the orifice path can be switched with a simple switching structure. In addition, since the occupied space occupied by the driving portion is small, there is an advantage that the size of the entire liquid sealing bush can be suppressed.

According to the invention described in claim 3, according to claim 2
In addition to the effects of the present invention, it is possible to set a plurality of types of vibration-proof characteristics at once with one liquid-filled bush. Moreover,
If replaced with a rotating member having an orifice passage or an orifice hole having different passage lengths, there is an advantage that various vibration-proof characteristics can be obtained.

According to the invention described in claim 4, according to claim 3,
In addition to the effects of the invention, various anti-vibration performances suitable for the running state required of the vehicle suspension device can be secured.

According to the fifth aspect of the present invention, the steering stability is improved when the damping characteristic is hardened, and the riding comfort is improved when the damping characteristic is softened. Thus, shimmy vibration can be reduced and straight running stability can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a liquid-filled bush according to an embodiment of the present invention, together with a front suspension device of an automobile to which the bush is applied.

FIG. 2A is a side view of the liquid-filled bush.
(B) is a sectional view showing the internal structure of the liquid-filled bush together with a state in which fluid chambers communicate with each other through orifice holes having a short passage length. (C) is a sectional side view around the fluid chamber and the spool along the line A-A in FIG. 2 (b).

FIG. 3 is a cross-sectional view for explaining a state when the space between fluid chambers of the liquid sealing bush is shut off.

FIG. 4 is a cross-sectional view for explaining a state when the fluid chambers of the liquid-filled bush are communicated via a U-shaped orifice passage formed in a spool.

FIG. 5 is a perspective view for explaining a mode of switching a spool with respect to an entrance and an exit of the liquid sealing bush.

FIG. 6 is a diagram for explaining vibration isolating characteristics provided by orifice holes and orifice passages of the liquid-filled bush.

[Explanation of symbols]

5: Liquid sealing bush 10: Body part of liquid sealing bush 11: Shaft member (first support member) 12: Outer cylinder member (second support member) 13: Elastic body 13a: A pair of entrances and exits 16a, 16b ... A pair of fluid chambers 17 ... liquid 19 ... spool (rotary member) 20 ... orifice hole 23 ... U-shaped orifice path 24 ... step motor (rotary drive source, drive means) 26 ... ECU (control unit) 27, 28, 29 , 30... A vehicle speed sensor, a steering wheel angle sensor, a road surface sensor, and a lateral G sensor (detection means for detecting the running state of the vehicle).

Claims (5)

[Claims] A main body configured by providing an elastic body between a shaft-shaped first support member and a cylindrical second support member disposed on the outer peripheral side of the support member; A pair of fluid chambers formed in an elastic body portion sandwiching the first support member and filled with fluid; and both ends formed along the axial direction of the first support member and both ends connected to each of the pair of fluid chambers A liquid-filling bush, comprising: an orifice passage; and a flow-path switching means for selectively communicating / cutting off the pair of fluid chambers or between the orifice passage and the pair of fluid chambers. 2. The shaft switching device according to claim 1, wherein the orifice passage is formed on an outer peripheral surface, and is inserted into the first support member so as to be rotatable around the axis of the support member. A rotating member, an inlet / outlet provided in the first support member for communicating the orifice path end with the fluid chamber, and a driving means for rotating and displacing the rotating member. The liquid-filled bush according to claim 1, wherein 3. The rotating member has an orifice hole penetrating in a diametrical direction at a portion different from the orifice passage, and the driving means drives a rotating member to connect the orifice passage and the orifice hole with each other. 3. The liquid-filled bush according to claim 2, wherein the liquid-filled bush is constituted by a motor that communicates with and shuts off a pair of fluid chambers. 4. The liquid-filled bush according to claim 3, wherein the motor is controlled by a control unit that connects and disconnects the orifice path and the orifice hole according to a traveling state of the vehicle. . 5. A main body comprising an elastic body provided between a shaft-shaped first support member and a cylindrical second support member disposed on the outer peripheral side of the support member; A pair of fluid chambers formed in an elastic portion sandwiching the support member and filled with a fluid, and the pair of fluid chambers can be communicated and blocked so that the damping characteristics can be varied hardly and softly. In the liquid sealing bush, there is further provided an orifice passage formed along the axial direction of the first support member and having both ends connected to each of the pair of fluid chambers, and selects the orifice passage and the pair of fluid chambers. A liquid-filled bush, characterized by the fact that it communicates and shuts off to attenuate shimmy vibrations in the low frequency range.