JPH06137361A - Liquid sealed vibration control device - Google Patents

Abstract

PURPOSE:To provide a liquid sealed vibration control device, of which vibration isolating characteristics can be changed to improve the drivability, by selectively switching a movable wall, which is arranged inside of an auxiliary liquid chamber, between the fixed condition and the non-fixed condition. CONSTITUTION:A liquid sealed vibration control device is provided with a main liquid chamber 5, a first auxiliary liquid chamber 8 having a first liquid sealed chamber 11 and a pressure reduction chamber 12, which are blocked by a first orifice 6, and a control port 13, which changes the first orifice 6 between the fixed condition and the non-fixed condition selectively to change the vibration isolating characteristics. This vibration control device is formed so that a difference of the liquid volume inside of the first auxiliary liquid chamber 8 between the time when the first orifice 6 is under the non-fixed condition and the vibration is not applied and the time when the first orifice 6 is under the fixed condition has a volume at 3% or less relative to the volume of the main liquid chamber 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-filled anti-vibration device, and more particularly to a structure for changing anti-vibration properties by selectively setting a movable wall disposed in a sub-liquid chamber into a fixed state / non-fixed state. Of the liquid-filled anti-vibration device.

[0002]

2. Description of the Related Art In an automobile engine, an engine provided with a vibration isolator between the engine and the body so that the vibration transmitted from the road surface is not directly transmitted to the engine and the vibration generated by the engine is not transmitted to the body. A mount is provided. Various types of structures are also provided for this vibration isolator, one of which is a liquid-filled vibration isolator.

In order to prevent vibrations having various characteristics such as idle vibration, engine shake, body shake, and acceleration / deceleration shock, the liquid filled vibration isolator has dynamic spring characteristics as a liquid filled vibration isolator. Some are configured to change.

This type of liquid-filled anti-vibration device has an elastic member made of rubber, a main liquid chamber in which a liquid is filled, and a sub-passage which communicates with this main liquid chamber through a throttle passage (orifice). It had a structure having a liquid chamber. Further, a diaphragm is movably arranged in the sub liquid chamber, and the sub liquid chamber is divided by the diaphragm into a liquid sealing chamber in which the liquid is sealed and an air chamber in which the liquid is not sealed. It is configured to. Further, negative pressure or atmospheric pressure is selectively introduced into the air chamber. In the liquid-filled anti-vibration device having the above structure, the diaphragm is movable and the dynamic spring constant is kept at a relatively low value when atmospheric pressure is introduced into the air chamber of the sub-liquid chamber.

On the other hand, in the state where a negative pressure is introduced into the air chamber of the sub liquid chamber, the diaphragm is fixed by the negative pressure in a state where the capacity of the liquid filling chamber is the maximum capacity, and is inoperable. Therefore, in this fixed state, the dynamic spring constant is substantially equal to the expansion elastic modulus of the elastic member and has a relatively high value.

As described above, in the conventional liquid-filled vibration isolator,
By selectively introducing negative pressure or atmospheric pressure to the air chamber of the sub liquid chamber, the dynamic spring characteristics as a liquid filled vibration isolation device are switched, and the dynamic spring characteristics adapted to the vibration characteristics that change in various operating conditions of the vehicle. It is configured to perform vibration isolation (for example, disclosed in Japanese Utility Model Laid-Open No. 63-35838).

[0007]

The liquid-filled anti-vibration device, whose spring constant can be changed as described above, has an anti-vibration effect which is adapted to different vibrations generated in an automobile, thus improving driver viability. Can be achieved.

However, conventionally, the volume of the air chamber in the sub liquid chamber is not particularly taken into consideration, and the diaphragm is constructed to have a relatively large volume so as not to hinder the movement of the diaphragm.

When a negative pressure is applied to the air chamber in such a structure, the diaphragm is largely displaced, and the volume of the liquid sealing chamber of the sub liquid chamber is greatly increased accordingly. In addition, since the negative pressure is large, the volume of the liquid sealing chamber is instantaneously increased when the negative pressure is applied, whereby the liquid in the main liquid chamber flows into the liquid sealing chamber of the sub liquid chamber through the orifice. Then
The pressure in the main liquid chamber drops sharply.

Therefore, the volume of the main liquid chamber is drastically reduced, and the height of the mount is accordingly reduced, so that the position of the engine supported by the liquid-filled vibration isolator momentarily moves downward, causing a large inertia. Power is generated. This inertial force is transmitted to the vehicle body, and this inertial force is felt by the driver as a large shock (a shock that "drops"),
There was a problem that the driver's ability deteriorated.

The present invention has been made in view of the above points, and a liquid for which the driver capacity is improved by optimizing the volume of the air chamber of the sub liquid chamber and suppressing the sudden increase of the volume of the main liquid chamber. It is an object of the present invention to provide an enclosed vibration isolation device.

[0012]

In order to solve the above problems, according to the present invention, a main liquid chamber in which a liquid is sealed and a movable wall which is displaceable are used to seal the inside of the liquid. In addition, the auxiliary liquid chamber defined by the first chamber communicating with the main liquid chamber by the throttle passage and the second chamber in which the liquid is not sealed, and the movable wall are selectively fixed. Or in a liquid-filled anti-vibration device including a control device that changes the anti-vibration property by switching to a non-fixed state,
The difference between the liquid volume in the sub liquid chamber when the movable wall is in the non-fixed state and when vibration is not applied and the liquid volume in the sub liquid chamber when the movable wall is in the fixed state is relative to the volume of the main liquid chamber. It is characterized by having a volume of 3% or less.

[0013]

When the movable wall is switched from the non-fixed state to the fixed state, the liquid-filled anti-vibration device has the above structure.
The amount of liquid flowing from the main liquid chamber to the sub liquid chamber is a small amount of 3% or less with respect to the volume of the main liquid chamber. Therefore, the volume of the main liquid chamber does not change so much, and the height of the mount does not decrease so much that the engine does not suddenly move downward. This allows
The inertial force generated by the sudden lowering of the engine is reduced, and the shock felt by the driver at the time of switching can be reduced.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a liquid filled vibration damping device 1 according to an embodiment of the present invention.

In the figure, reference numeral 2 denotes a main body made of rubber, and an engine mounting member 3 to which an engine is mounted is arranged above the main body. Also, the main body 2
A partition member 4 is disposed in the lower portion of the partition member 4, and a main liquid chamber 5 is formed by the upper surface of the partition member 4 and the recess 2a formed in the lower surface of the main body 2.

The partition member 4 has a first orifice 6, a second orifice 7, a first sub-liquid chamber 8 and a second sub-liquid chamber 9 formed in this order from the upper position. The first orifice 6 (throttle passage) is a passage that connects the main liquid chamber 5 and the first sub liquid chamber 8 and has a predetermined cross-sectional area. The first orifice 6 is formed in a spiral shape inside the partition member 4 in order to increase the passage length. Therefore, the first orifice 6 has a predetermined flow path resistance as a flow path.

The second orifice 7 is a passage that connects the main liquid chamber 5 and the second auxiliary liquid chamber 9 via the first orifice 6. Like the first orifice 6, the second orifice 7 is formed in a spiral shape inside the partition member 4 to increase the passage length thereof. Further, the second orifice 7 is set to have a smaller cross-sectional area than the first orifice 6, and the flow passage resistance is larger than that of the first orifice 6.

Further, a first diaphragm (movable wall) 10 is arranged in the first sub liquid chamber 8, and a liquid having a predetermined viscosity is sealed in the first sub liquid chamber 8 by the first diaphragm 10. It is divided into a first liquid sealing chamber (first chamber) 11 and a decompression chamber (second chamber) 12 in which liquid is not sealed.
The first liquid enclosing chamber 11 is communicated with the main liquid chamber 5 through the first orifice 6, and the enclosed liquid passes through the first orifice 6 to connect between the main liquid chamber 5 and the first liquid enclosing chamber 11. It is structured so that you can come and go. Further, since the first orifice 6 has a predetermined flow path resistance as described above, the liquid is stored in the main liquid chamber 5
A viscous damping action occurs when flowing between the first liquid sealing chamber 11 and the first liquid sealing chamber 11. Further, a control port 13 is connected to the decompression chamber 12.

FIG. 2 shows the structure of a vibration isolation system to which the liquid-filled vibration isolation device 1 is applied. As shown in the figure, the control port 13 is connected to a vacuum tank 19 via a solenoid valve 18. Also, vacuum tank 1
Reference numeral 9 is connected to the intake manifold via a check valve 20 and a pipe 21. Therefore, when the negative pressure of the intake manifold is applied to the vacuum tank 19, the vacuum tank 19 also becomes negative pressure, and by providing the check valve 20, the vacuum tank 19 can maintain the negative pressure. .

The solenoid valve 18 is connected to a control unit 22 and its drive control is performed by this control unit 22. The solenoid valve 18 selectively connects the control port 13 to the vacuum tank 19 or the atmosphere open pipe 23. Therefore, when the control port 13 and the vacuum tank 19 are connected by the operation of the solenoid valve 18, the vacuum tank 1 that functions as a negative pressure source in the decompression chamber 12
Negative pressure of 9 is applied, while operation of the solenoid valve 18 causes
When the control port 13 and the atmosphere opening pipe 23 are connected, the decompression chamber 12 becomes atmospheric pressure.

The control unit 22 is composed of a microcomputer, and in addition to the solenoid valve 18, for example, an idle switch for detecting that the throttle valve is in the idle position, a rotation speed sensor for detecting the engine speed, A vehicle speed sensor for detecting the vehicle speed, a steering angle sensor for detecting the steering angle (turning angle) of the vehicle, etc. are connected. Based on the data supplied from each of these sensors, the control unit 22 operates the solenoid valve 18 to perform the characteristic switching control of the liquid filled vibration damping device 1 described later.

Returning to FIG. 1 again, the description of the structure of the liquid-filled vibration isolator 1 will be continued.

A second diaphragm (movable wall) 14 is disposed in the second auxiliary liquid chamber 9, and this second diaphragm 14 is provided.
Thus, the second sub liquid chamber 9 is divided into a second liquid sealing chamber 15 in which liquid is sealed and an air chamber 16 in which liquid is not sealed.
The second liquid sealing chamber 15 is in communication with the main liquid chamber 5 through the first and second orifices 6 and 7, and the liquid sealed therein is the first liquid.
Also, the main liquid chamber 5 and the second liquid sealing chamber 15 can be moved back and forth through the second orifices 6 and 7. Further, as described above, since the flow path resistance of the second orifice 7 is very large, the liquid is the main liquid chamber 5 and the second liquid sealing chamber 1.
When flowing between the first and second orifices 5, a viscous damping action which is larger than that of the first orifice 6 is generated. On the other hand, since the atmosphere opening hole 17 is formed in the air chamber 16 and the inside of the air chamber 16 is always kept at the atmospheric pressure, the second diaphragm 14 is always movable.

Next, the operation of the liquid-filled anti-vibration device 1 configured as described above will be described.

When the vehicle is in the idle state, the control unit 22 detects from the signal from the idle switch that the vehicle is in the idle state, and operates the solenoid valve 18 so that the control port 13 and the atmosphere opening pipe 23 are connected. Control. As a result, the decompression chamber 12 is communicated with the atmosphere via the control port 13, the solenoid valve 18, and the atmosphere opening pipe 23. In this state (the state shown in FIG. 1), the first diaphragm 10 is in a freely movable state (non-fixed state) in the first sub liquid chamber 8, and the main liquid chamber 5 and the first liquid sealing chamber 11 are provided. The liquid in the chambers 5 and 11 passes through the first orifice 6 and
It is structured so that you can move back and forth.

In the non-fixed state, the rubber main body 2
Only the compressive force due to the loading weight of the liquid-filled vibration isolator 1 acts on this, and the liquid in the main liquid chamber 5 can flow into the first liquid-filled chamber 11 through the first orifice 6 that exerts a viscous damping action. Since it is in such a state, the main body 2 itself is in a relatively low dynamic spring constant state. Therefore, the liquid-filled vibration isolation device 1 as a whole exhibits low dynamic spring characteristics,
Idle vibration is effectively reduced.

On the other hand, in a state other than the idle state (for example, a running state), the control unit 22 controls the operation of the solenoid valve 18 so that the control port 13 and the vacuum tank 19 are connected. As a result, the decompression chamber 12 is controlled by the control port 1
3. A negative pressure in the vacuum tank 19 is applied to the decompression chamber 12 by communicating with the vacuum tank 19 via the solenoid valve 18. In this state, the first diaphragm 10 is sucked by the negative pressure and is stuck to the bottom wall 8a of the first auxiliary liquid chamber 8 (fixed state). In this fixed state, substantially the entire first sub-liquid chamber 8 is the first liquid sealing chamber 11 and is filled with liquid, so that the main liquid chamber 5 and the first liquid sealing chamber 11 are separated from each other. Liquid cannot flow between them. Therefore, the liquid is configured to move back and forth between the main liquid chamber 5 and the second liquid sealing chamber via the first and second orifices 6 and 7. Further, as described above, the second orifice 7 is set to have a small cross-sectional area and a very large flow resistance.

Therefore, even if the rubber main body 2 is elastically deformed, the flow of liquid between the main liquid chamber 5 and the second liquid sealing chamber 15 is small, so that the dynamic spring constant of the main body 2 becomes very high.
As a result, the dynamic spring characteristics of the liquid-filled vibration isolation device 1 as a whole also have high values. Further, the damping effect of the liquid-filled vibration isolator 1 as a whole increases due to the mass effect (liquid column resonance) of the liquid in the second orifice 7. By increasing the spring and damping of the liquid-filled anti-vibration device 1, the acceleration shock can be effectively suppressed and the engine shake can also be effectively suppressed.

Next, the operation of the liquid-filled vibration isolator 1 immediately after the negative pressure is applied to the decompression chamber 12 (immediately after switching the characteristics), which is a feature of the present invention, will be described.

At the time of switching the characteristics, a negative pressure is applied to the decompression chamber 12, the first diaphragm 10 is sucked by this negative pressure and displaced from the state shown in FIG. 1, and the bottom wall 8a of the first auxiliary liquid chamber 8 is displaced. It will be stuck and fixed.

Here, for convenience of explanation, the problems of the above-mentioned conventional apparatus will be briefly described with reference to FIG. In the conventional liquid-filled vibration isolator, since the volume of the decompression chamber (12) is large and the volume has not been optimized, the displacement of the first diaphragm (10) at the time of switching the characteristics is large, which causes the main liquid chamber A large amount of the liquid in (2) flows into the first liquid sealing chamber (11) through the first orifice (6), and the volume of the main liquid chamber (2) is rapidly reduced, whereby the engine mounting position is increased. Momentarily moved downward, generating a large inertial force, causing a large shock.

The shock generated when the characteristics are switched is mainly caused by the inertial force due to the acceleration when the engine moves due to the decrease in the mounting height of the engine. Therefore, in order to reduce this shock, it is important to reduce the acceleration when the engine is moving.

FIG. 3A shows the amount of decrease in the mount height position of the engine (hereinafter simply referred to as the amount of decrease x) when the volume of the decompression chamber 12 is changed, and FIG. 3 (B). Similarly, changes in the inertial force (F) when the volume of the decompression chamber 12 is changed are shown respectively. Further, in the same drawing, the curves showing the respective characteristics are distinguished by adding arrows A1 to A5 in the order of decreasing volume of the decompression chamber 12. Therefore, the arrow A1 is the characteristic curve when the volume of the decompression chamber 12 is the smallest, and the arrow A5 is the characteristic curve when the volume of the decompression chamber 12 is the largest. In the figure, the horizontal axis represents time.

Examining this figure, it can be seen from FIG. 9A that the amount of decrease x increases as the volume of the decompression chamber 12 increases. Further, the change has a mountain-shaped change characteristic in which the change first gradually increases with the passage of time, then reaches the maximum decrease amount, and then gradually decreases. The increase characteristics are almost the same. Here, in the same figure (A), arrow A1'-A5 '
The point indicated by is the point where the maximum reduction amount is reached.

As described above, the characteristic of the decrease amount x becomes a mountain-shaped change characteristic, after the displacement of the first diaphragm 10 reaches the maximum decrease amount, the second liquid sealing chamber 15 to the main liquid chamber 5 are changed.
This is because the liquid flows in through the first and second orifices 6 and 7, and exhibits substantially the same increasing characteristics when increasing. The negative pressure applied to the decompression chamber 12 is equal to the volume of the decompression chamber 12. This is because it is constant regardless of.

Now, the magnitude of the shock generated in the vehicle will be described with reference to FIGS. 4 and 5.

The magnitude of the shock is point A, which is the maximum reduction amount.
The rate of change of the lowering speed x ′ (x ′ is a one-time differential value of the lowering amount x) at the height position of the engine mount in the vicinity of 1 ′ to A5 ′, that is, the lowering acceleration x ″ (x ″ is twice the lowering amount x. It is greatly influenced by the differential value, and as this rate of change increases, a larger load (inertial force) occurs and a larger shock occurs. That is, in the mountain-shaped change characteristic curve of the decrease amount x, the sharper the tip end (maximum decrease part), the greater the shock. This is because when the mass of the engine is a (constant value), the load (inertial force) F is calculated by F = a · x ″, and the magnitude of the load (inertial force) F becomes the reduced acceleration x ″. This is because they are proportional.

The above matters will be described in more detail with reference to FIG.
FIG. 4 is a diagram in which a decrease amount x, a decrease speed x ′, and a decrease acceleration x ″ in the case where a negative pressure is applied to the decompression chamber 12 having a certain volume are associated with each other in time series.

Therefore, looking at the change in the amount of decrease x shown in FIG. 9A, the decompression chamber 12 is between time t ₀ and t _2.
This is a start region where a negative pressure is applied to the mount and the mount decrease amount x starts to increase. Further, the times t _{2 to} t ₄ are constant increase regions in which the mount decrease amount x increases at a constant rate. Further, it is a maximum area in which the mount decrease amount x takes the maximum value from time t _{4 to} t ₆ (hereinafter, the maximum mount decrease amount is referred to as x _max ). Further, during the time t _{6 to} t ₈ , it is a constant decrease region in which the mount decrease amount x decreases at a constant rate. On the other hand, as shown in FIG. 6B, the maximum value of the decreasing speed x ′ is at time t ₃ and time t ₇ , and as shown in FIG. Time t ₁ (the maximum value of the decreasing acceleration x ″ at this time t ₁ is x ″ _max1 ) and time t ₂ (the maximum value of the decreasing acceleration x ″ at this time t ₂ is x ″ _max2 . t ₁
The direction of acceleration is opposite to that at time).

Here, the maximum value of the decreasing acceleration x ″ is x ″.
Fig. 5 shows the characteristics of the amount of decrease x in the start region where _{max1 is} taken.
FIG. 5B shows the characteristics in (A) and in the maximum region where the decreasing acceleration x ″ takes the maximum value x ″ _max2 . In each figure, the decreasing acceleration x ″ is defined as the rate of change (ie, differential value) of the slope of the curve indicating the decreasing amount x (hereinafter referred to as the decreasing amount curve). Therefore, the maximum value x ″ _max1 of the decreasing acceleration is As shown in FIG. 5 (A), it is the rate of change of the slope of the decrease amount curve at time t ₁ (indicated by the arrow in the figure), and the maximum value x ″ _max2 of the decrease acceleration is as shown in FIG. 5 (B). At time t
It is the rate of change of the slope of the drop curve in ₂ (this slope is indicated by the arrow in the figure).

Further, as described above, the magnitude of the inertial force F that causes the shock is proportional to the decreasing acceleration x ". Therefore, in order to suppress the shock, the maximum value is x" _max1 and the maximum value. May be configured to suppress the value of x ″ _max2 to a low value. This can be _achieved by reducing the angles indicated by arrows in FIGS. 5 (A) and 5 (B). It means that you can do it.

On the other hand, since the slope of the decrease amount curve (decrease speed x ') in the constant increase region does not depend on the volume of the decompression chamber 12 (see FIG. (A)), the maximum decrease amount x after entering the constant increase region x _{When the} configuration is such that _max is set, the maximum values x ″ _max1 and x ″ _max2 of the reduced acceleration take a large constant value regardless of the volume of the decompression chamber 12. Therefore, the inertial force F can be reduced by configuring the decreasing acceleration to take the maximum value before reaching the constant region increasing region, that is, in the starting region.

Here, the portion surrounded by a circle in FIG. 3 (A) is shown in FIG.
It is enlarged and shown in (C) and (D). Further, FIG. 5 (C) is a diagram for explaining the maximum value x _{"ma x1} reduction acceleration during lowering the start of the mounting, FIG. 5 (D) is reduced acceleration at the time that the maximum decrease in the mount FIG. 6 is a diagram for explaining the maximum value of x ″ _max2 .

As shown in FIG. 5 (C), the maximum value x ″ _max1 of the deceleration at the time of starting the demounting of the mount becomes large when the volume of the decompression chamber is large (indicated by the arrow A2), and also the decompression chamber. It is understood that when the volume of the mount is small (indicated by the arrow A1), the maximum value of the decrease acceleration when the maximum amount of decrease of the mount becomes the maximum value x ″ _max2 is also reduced from FIG. It can be seen that when the volume of the chamber is large, it becomes large, and when the volume of the decompression chamber is small, it becomes small. Therefore, it is understood from the above matters that the volume of the decompression chamber 12 should be reduced in order to reduce the shock.

On the other hand, if the volume of the decompression chamber 12 is V ₁ ,
The relationship between the volume V ₁ of the decompression chamber 12 and the maximum reduction amount x _max is expressed by the following equation.

X _max = {K _L · K _C / (K _L + K _C ) · K _S } × V ₁ However, in the above formula, K _L : expanded spring constant K _C : filled liquid compressibility K _S : static spring constant In the above equation, the expansion spring constant K _L , the enclosed liquid compressibility K _C ,
Since the static spring constant K _S is a constant value peculiar to the liquid-filled vibration isolator, the maximum reduction amount x _max is the volume V _{1 of the} decompression chamber 12.
Proportional to. Therefore, in order to reduce the maximum reduction amount x _{max in} order to reduce the shock generated when switching the characteristics,
It can be seen that it is effective to make the volume V ₁ of the decompression chamber 12 extremely small.

However, even if the volume V ₁ of the decompression chamber 12 is simply reduced, how much the volume should be reduced depends on the vehicle type to which the liquid-filled vibration isolation device 1 is applied. That is, the liquid-filled anti-vibration device 1 for mounting a multi-cylinder engine with a large engine weight has a large shape, and the liquid-filled anti-vibration device 1 for mounting an engine for a light vehicle has a small shape. I can't think of it. Therefore, the ratio (V ₁ / V: hereinafter referred to as volume ratio) between the volume V of the main liquid chamber 5 and the volume V _{1 of the} decompression chamber is calculated, and the volume reduction amount of the decompression chamber 12 for preventing shock is calculated based on this ratio. Quantified. Further, as described above, the decompression chamber volume V ₁ is a value that changes depending on the loading weight applied to the liquid-filled vibration damping device 1, so that the decompression chamber volume V ₁ in the state in which the loading weight is not applied is used as a reference. did. In addition, this decompression chamber volume V
₁ is the liquid volume in the first sub liquid chamber 8 when the first diaphragm 10 is not fixed and no vibration is applied, and the liquid volume in the first sub liquid chamber 8 when the first diaphragm 10 is fixed. Is equivalent to the difference.

FIG. 3 shows the relationship between the volume ratio (V ₁ / V) and the generated inertial force (F). From the figure, when the volume ratio (V ₁ / V) becomes a predetermined value or more, the inertial force (F) becomes a large value F ₁ (this value is the inertial force value at which a large shock occurs), and the volume ratio (V _The inertial force (F) generated becomes small when ( ₁ / V) becomes a predetermined value or less. Now, assuming that the threshold value of the inertial force at which a shock is not felt is F ₀ , the inertial force is less than F ₀ when the volume ratio (V ₁ / V) is 3% or less. Therefore, by configuring the first sub-liquid chamber 8 so that the volume ratio (V ₁ / V) is 3% or less, it is possible to suppress the occurrence of shock and improve the driver accessibility.

Further, the volume ratio (V ₁ / V) is set to 3% or less to reduce the volume of the decompression chamber 12 so that the negative pressure suction is started to the first diaphragm 10 at the time of switching the characteristics. It is possible to shorten the time until the 10 is completely fixed, and improve the response of the characteristic switching. As a result, irregular vibration that occurs during the response delay time is eliminated, and this also improves driver viability.

Further, by reducing the volume of the decompression chamber 12, the structure of the control device required for displacing the first diaphragm 10 can be simplified, and the cost and the weight can be reduced.

Although the vacuum tank 19 is used as the means for displacing the first diaphragm 10 at the time of switching the characteristics in the above-mentioned embodiment, the first diaphragm 10 may be displaced by another structure.

[0052]

As described above, according to the present invention, when the movable wall is switched from the non-fixed state to the fixed state, the amount of the liquid flowing from the main liquid chamber to the sub liquid chamber is 3 with respect to the main liquid chamber volume. %, The change in volume of the main liquid chamber is small, and the height of the mount is not so much lowered that the engine does not suddenly move downward. It has features such as a smaller size and a shock that the driver feels when switching the characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid filled vibration damping device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a vibration isolation system to which the liquid filled vibration isolation device according to an embodiment of the present invention is applied.

FIG. 3 (A) shows how the amount of decrease x changes when the volume of the decompression chamber is changed, and (B) shows the change of the inertia force F when the volume of the decompression chamber is changed. 6C is a diagram showing the relationship between the volume ratio (V ₁ / V) and the generated inertial force F. FIG.

FIG. 4 is a diagram showing a reduction amount, a reduction speed, and a reduction acceleration in association with each other.

FIG. 5A shows the characteristic of the reduction amount x in the start region where the reduction acceleration x ″ takes the maximum value x ″ _max1 .
(B) shows the characteristic in the maximum region where the reduced acceleration x ″ takes the maximum value x ″ _max2 , and (C) is a diagram for explaining the maximum value x ″ _max1 of the reduced acceleration when the mount starts to be lowered. FIG. _3D is a diagram for explaining x ″ _max2, which is the maximum value of the decrease acceleration when the maximum decrease amount of the mount is reached.

[Explanation of symbols]

 1 Liquid Filled Vibration Isolator 2 Main Body 4 Partition Member 5 Main Liquid Chamber 6 First Orifice 7 Second Orifice 8 First Sub Liquid Chamber 8a Bottom Wall 9 Second Sub Liquid Chamber 10 First Diaphragm 11 First Liquid Filled Chamber 12 Decompression chamber 13 Control port 14 Second diaphragm 15 Second liquid sealing chamber 16 Air chamber 18 Solenoid valve 19 Vacuum meter 22 Control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Matsumura 3600 Amami, Kita Sotoyama, Komaki City, Aichi Prefecture Tokai Rubber Industry Co., Ltd. Address Tokai Rubber Industry Co., Ltd.

Claims (1)

[Claims] 1. A first liquid chamber in which a main liquid chamber in which a liquid is sealed and a movable wall which is displaceable is provided, the inside of which is filled with the liquid and communicated with the main liquid chamber by a throttle passage. A sub-liquid chamber defined by a room and a second room in which the liquid is not enclosed, and control for changing the vibration damping characteristics by selectively switching the movable wall to a fixed state or a non-fixed state. And a liquid volume in the sub liquid chamber when the movable wall is in the non-fixed state and no vibration is applied, and a liquid in the sub liquid chamber when the movable wall is in the fixed state. A liquid-filled anti-vibration device, characterized in that it has a volume difference of 3% or less with respect to the volume of the main liquid chamber.