JP2827580B2 - Liquid filled vibration isolator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid filled vibration damping device, and more particularly to a liquid filled vibration damping device in which a part of a liquid chamber is made of an elastic material.

[0002]

2. Description of the Related Art In an automobile engine, an engine provided with a vibration isolator between an engine and a body so that vibration transmitted from a road surface is not directly transmitted to the engine and vibration generated by the engine is not transmitted to a body. A mount is provided.

[0003] Various types of vibration isolators are also provided, and one of them is a liquid-filled vibration isolator. This liquid-filled vibration isolator has a pair of liquid chambers in which liquid is sealed, and the pair of liquid chambers has an orifice (small hole).
Are communicated through. Further, the liquid chamber is partially constituted by an elastic body (rubber or the like), and this elastic body portion is configured to be elastically deformable.

In the above-described liquid-filled vibration isolator, when input vibration such as road surface vibration is transmitted, the input vibration is transmitted to the liquid chamber, thereby changing the volume of the liquid chamber. When the volume of the liquid chamber changes, the liquid passes through the orifice and moves between the pair of liquid chambers according to the change in the volume, whereby the input vibration is attenuated by the damping effect, and the input vibration between the engine and the body is reduced. It was configured to prevent transmission.
No. 3-180753).

[0005]

However, in the above-described liquid-filled vibration isolator, the elastic body constituting a part of the liquid chamber is made of a homogeneous material such as rubber, so that an external force can be applied to the liquid chamber from any direction. Is deformed with the same characteristics even when the pressure is applied.

On the other hand, as is well known, there are two types of vibrations to be attenuated by the liquid filled vibration isolator, that is, a low frequency region and a high frequency region. The vibration in the low frequency region is mainly transmitted from the road surface, and if the vibration is large, the driver viability deteriorates. The vibration in the high frequency region is mainly a high frequency vibration generated by the engine, and is called a noise region.

From the viewpoint of improving the high frequency vibration isolation characteristics,
It is desirable to use an elastic body having a small spring constant for the material of the liquid chamber. However, if the spring constant of the material of the liquid chamber is determined by focusing only on the high-frequency vibration isolation characteristics, when low-frequency vibration is applied to this liquid chamber, the liquid chamber expands due to the small spring constant and the volume increases. turn into.

As described above, in the liquid-filled vibration isolator, the volume of the liquid chamber changes due to the input of vibration, and the liquid moves between the pair of liquid chambers through the orifice with the change in volume.
Thereby, it is configured to exhibit an attenuation effect. However, in the liquid chamber having a small spring constant and swelling due to the application of low-frequency vibration as described above, the liquid chamber is deformed so as to increase the volume of the liquid chamber, so that the amount of liquid passing through the orifice is small. Therefore, if the spring constant of the elastic body that constitutes the liquid chamber is set low by focusing only on the high-frequency vibration isolation characteristics, the amount of fluid passing through the orifice decreases due to the swelling of the elastic body in the low-frequency range, and the necessary damping force decreases. No longer obtainable, and driver viability deteriorates. Conversely, if the spring constant of the material of the liquid chamber is determined by paying attention only to the low-frequency vibration isolation characteristics, it becomes impossible to effectively prevent high-frequency vibration isolation, resulting in severe noise. As described above, the conventional liquid-filled vibration damping device has a problem that both low-frequency vibration and high-frequency vibration cannot be effectively damped.

The present invention has been made in view of the above points, and by providing orientation to the spring constant of an elastic body constituting a liquid chamber, both low-frequency vibration and high-frequency vibration can be effectively damped. An object of the present invention is to provide a liquid filled vibration isolator.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a pair of liquid chambers in which liquid is sealed are communicated via an orifice, and a volume change of the liquid chamber caused by input vibration causes In the liquid filled vibration isolator, in which the liquid passes through the orifice and moves between the pair of liquid chambers to generate a damping effect, the elastic body constituting a part of the liquid chamber does not match the input vibration. It is characterized by incorporating short fibers oriented in the direction.

[0011]

As described above, the elastic body constituting a part of the liquid chamber is blended with the short fibers oriented in the direction not coincident with the input vibration, so that the spring of the liquid chamber in the direction coincident with the input vibration is formed. The constant has substantially the same value as the inherent spring constant of the elastic body, and the spring constant in a direction that does not coincide with the input vibration becomes a value larger than the inherent spring constant of the elastic body by blending the short fibers.

The direction that does not coincide with the input vibration is the direction in which the liquid chamber expands in the conventional device. Therefore, since the spring constant in the direction in which the liquid chamber expands due to the application of the input vibration becomes a large value, the expansion of the liquid chamber can be prevented. Accordingly, the amount of liquid passing through the orifice can be increased, and vibration in a low frequency region can be prevented.

Further, the spring constant of the liquid chamber in the direction coinciding with the input vibration is substantially the same as the inherent spring constant of the elastic body, so that the value is small. Therefore, the elastic body constituting the liquid chamber absorbs the vibration in the high-frequency region, so that the vibration can be effectively prevented also in the high-frequency region.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a liquid filled vibration isolator 1 according to a first embodiment of the present invention.

In FIG. 1, reference numeral 2 denotes a main body rubber which is a feature of the present invention (details will be described later), and has a first liquid chamber (hereinafter, referred to as a main chamber) inside a cylindrical shape.
3 is formed with a concave portion 2a. Also,
An engine-side mounting bolt 4 is provided upright on the upper portion of the main rubber 2 and a mounting flange 5 is provided. Further, a side plate 6 made of metal such as aluminum die cast is provided on a side portion of the main rubber 2.

At the lower part of the side plate 6, a bottom plate 7 also made of metal such as aluminum die cast is caulked. When the bottom plate 7 is attached to the side plate 6, a fixing member 8 and a rubber film 9 are attached between the side plate 6 and the bottom plate 7.

At the center of the fixing member 8, a rubber intermediate plate 15 is attached so as to be vertically displaceable in the drawing. A body mounting bolt 12 extending downward is planted at the center of the bottom plate 7.

In the above configuration, the concave portion 2 of the main rubber 2
a, the fixing member 8 and the intermediate plate 15 cooperate to form the main chamber 3, and the fixing member 8 and the rubber film 9 cooperate to form the second liquid chamber (hereinafter referred to as the sub chamber) 10. The bottom plate 7 and the rubber film 9 cooperate to form an air chamber 14. The main chamber 3 and the sub-chamber 10 are filled with the liquid 11, and each chamber 3,
An orifice 8a is provided on the fixing member 8 disposed between
The main chamber 3 and the sub-chamber 10 are communicated by the orifice 8a. Further, a ventilation hole 13 is formed near the planting position of the body mounting bolt 12 on the bottom plate 7, and the air chamber 14 is opened to the atmosphere by the ventilation hole 13.

Next, the structure of the main rubber 2 will be described.

The main rubber 2 has a structure in which short fibers are oriented and compounded in a relatively soft rubber. As a specific forming method, when compression molding is used as a molding means, unvulcanized rubber containing short fibers is caused to flow in a flow path, and short fibers are made using a difference in flow velocity in the flow path. Are oriented in one direction. When injection formation is used, the short fibers are oriented in one direction by utilizing the property that the compounded short fibers are oriented in the direction in which the rubber flows in the mold.

FIG. 2 is a sectional view taken along the line AA in FIG. 1. The short fibers 16 are indicated by "-".
As shown in the figure, the short fibers 16 are configured to be radially oriented. As described above, when the main rubber 2 is composed of the rubber compounded by orienting the short fibers 16, a tensile load or a compressive load is applied to the main rubber 2 in a radial direction (for example, an arrow B direction). The spring constant of
This is a large value compared to the spring constant of a single rubber that does not contain the short fibers 16. This is because the compounded short fibers 16 are oriented in the same direction as the load application direction, and thus function as a reinforcing material.

On the other hand, when a tensile load or a compressive load is applied in a direction perpendicular to the above-mentioned radial direction (perpendicular to the plane of the drawing), the spring constant of the rubber alone without the short fibers 16 is determined. This is almost the same value as the constant. this is,
This is because the blended short fibers 16 are oriented in a direction different from the direction in which the load is applied, so that the short fibers 16 do not significantly affect the elastic deformation of the main rubber 2.

As described above, the main rubber 2 has a different spring constant depending on the direction of the applied load. Therefore, in FIG. 1, even if a load is applied to the main rubber 2 to deform the main rubber 2 in the X direction (this direction is a direction different from the direction in which the input vibration is applied), the spring constant in this direction is applied. Is large, the main body rubber 2 is not deformed, so that the swelling of the main chamber 3 is prevented. In addition, when a load is applied to the main rubber 2 to deform the main rubber 2 in the Y direction (this direction is the same as the direction in which the input vibration is applied), the spring constant in this direction is small. The main rubber 2 can easily undergo elastic deformation.

In this embodiment, the specific configuration of the main rubber 2 is a rubber base having a rubber hardness of 9 to 45 Hs.
Natural rubber (according to JIS6301, vulcanized rubber physical test method) was used, and short fibers having an average diameter of 0.3 to 10 μm and a length of 15 to 100 μm were used. The content of the short fibers with respect to the natural rubber was set to 10 to 15 wt%.

Next, the operation of the liquid-filled vibration isolator 1 having the above configuration when vibration is applied will be described (hereinafter, the vibration applied to the liquid-filled vibration isolator 1 is referred to as input vibration). The input vibration is applied to the liquid filled vibration isolator 1 in the direction of arrow Y in FIG. In addition, as described above, there are two types of input vibration, low-frequency vibration and high-frequency vibration. First, an operation when low-frequency vibration is input as input vibration will be described.

When low-frequency vibration is input to the liquid-filled vibration isolator 1 as input vibration, the low-frequency vibration has a large amplitude and cannot be absorbed by elastic deformation of the main rubber 2 alone. For this reason, the low frequency vibration is attenuated by the damping effect generated when the liquid 11 passes through the orifice 8a. Specifically, when the input vibration is applied, the internal pressure of the main chamber 3 increases, and the amount of the liquid 11 passing through the orifice 8a increases due to the internal pressure. The internal pressure acts to expand the main chamber 3 in the direction of the arrow X in the figure (specifically, in the radial direction of the main rubber 2). However, as described above, the liquid-filled vibration isolator 1 according to the present invention has a configuration in which the main rubber 2 is compounded with the short fibers 16 so as to have a predetermined orientation, so that the spring constant in the X direction is large. Therefore, the main rubber 2 is not deformed in the X direction, so that the swelling of the main chamber 3 is prevented.

Therefore, the volume of the main chamber 3 changes only in the direction of the arrow Y, and the volume of the main chamber 3 becomes smaller. As a result, the liquid 11 filled in the main chamber 3 becomes the orifice 8a.
And flows into the sub-chamber 10. At this time, since the swelling of the main chamber 3 does not occur, the liquid 11 flowing from the main chamber 3 to the sub chamber 10
, The amount of inflow increases, and the damping efficiency can be improved.

FIG. 3 shows the relationship between the spring constant (K _X ) and the frequency of the main rubber 2 in the X direction in FIG. 1 and the relationship between the damping coefficient (C) and the frequency of the input vibration. In the same figure, the solid line shows the characteristics of the main rubber 2 according to the present invention in which the short fibers 16 are compounded, and the broken lines show the characteristics of the conventional main rubber without compounding the short fibers.

As can be seen from FIG. 2, the spring constant K _X and the damping constant C of the main rubber 2 according to the present invention are both higher than those of the conventional rubber, and the tendency is particularly remarkable in a low frequency region. Thus, since the spring constant K _X is high in the rubber body 2 in particular low-frequency region, by applying the rubber body 2 in the fluid filled vibration damping device 1, when the low-frequency vibrations is input as input vibration The bulging of the main chamber 3 can be prevented, an effective anti-vibration effect against low-frequency vibration can be realized, and the attenuation coefficient C has a large value in the low-frequency region, and the attenuation efficiency in the low-frequency region is good.

As is clear from the results shown in FIG.
By increasing the spring constant K _X for 6 was oriented blended 1 in X direction of the main body rubber 2, it can be carried out particularly effectively the vibration damping of the input vibration in a low frequency.

Next, the operation of the liquid filled vibration isolator 1 when high-frequency vibration is input as input vibration will be described. The operation when the high frequency vibration is input as the input vibration to the liquid filled vibration isolator 1 is a feature of the present invention,
This high frequency vibration is prevented by the main rubber 2.

As described above, the spring constant of the main rubber 2 in FIG. 1 is different from the spring constant in the direction of the arrow X and the spring constant in the direction of the arrow Y. The spring constant for the direction has a small value. In particular, since the base rubber of the main rubber 2 according to the present application is a soft rubber having a rubber hardness of 9 to 45 Hs, the spring constant in the Y direction is smaller than the spring constant of the main rubber of the conventional device. I have. As described above, by reducing the spring constant in the Y direction (input direction of input vibration), high-frequency vibration is generated by the main rubber 2 itself (the main chamber 3).
And without deformation of the sub-chamber 10).

FIG. 4 shows the relationship between the spring constant (K _X ) and the frequency of the main rubber 2 in the X direction in FIG. Also in this figure, the solid line shows the characteristics of the main rubber 2 according to the present invention in which the short fibers 16 are compounded, and the broken lines show the characteristics of the conventional main rubber without compounding the short fibers. As shown in the figure, the main rubber 2 has a lower spring constant than the conventional main rubber 2 particularly in a high frequency region, and it can be seen that the main rubber 2 has a configuration capable of effectively preventing vibration in a high frequency region.

It is known that when an elastic body having a small spring constant is used as a vibration-proof material, high-frequency vibration can be effectively prevented. However, since the main rubber used in the conventional device had the same spring constant for loads in all directions, the main rubber was made of a material with a small spring constant to cope with high-frequency input vibration. When the low frequency vibration is input, the main room expands, and it becomes impossible to effectively perform the vibration isolation against the low frequency vibration.
Therefore, in the conventional device, it is necessary to set the spring constant of the main body rubber high so as to be able to cope with low frequency vibration.
As described above.

However, according to the present invention, the main rubber 2 can have a different spring constant depending on the direction of the applied load.
By using the above, only the spring constant in the same direction as the input direction of the input vibration could be reduced.

As described above, by forming the structure of the main rubber 2 into a structure in which short fibers are oriented and blended in a relatively soft rubber, the vibration isolation characteristics of the liquid-filled vibration isolator 1 against low-frequency vibration, and It is possible to improve the vibration isolation characteristics against high-frequency vibration.

FIG. 5 shows a longitudinal section of a liquid filled vibration isolator 20 according to a second embodiment of the present invention. The liquid-filled anti-vibration device 20 shown in FIG. 1 is called a so-called cylindrical mount, and has a configuration in which a main rubber 23 is disposed between an outer cylinder 21 and an inner cylinder 22. In the figure, reference numeral 24 denotes a main chamber, 25 denotes a sub chamber, and 26 denotes an air chamber. Main room 24 and sub room 2
5 is filled with a liquid 27, and the liquid 27 is communicated by an orifice groove (not shown in the figure) formed in an orifice plate 28 disposed on the inner peripheral side of the outer cylinder 21. Further, the sub chamber 25 and the air chamber 26 are defined by a diaphragm 29. In the drawing, reference numeral 30 denotes a movable block, which is provided to secure the flow of the liquid 27 when the input vibration is applied.

The inner cylinder 22 is disposed at a position eccentric with respect to the center position of the outer cylinder 21. Specifically, in each figure, the inner cylinder 22 is disposed so that the center position of the inner cylinder 22 is lower than the center position of the outer cylinder 21. Further, the input vibration is configured to be applied in a vertical direction in each drawing. When the input vibrations in a liquid filled vibration isolating device 20 of the above configuration is input, or relatively outer tube 21 by the input vibration is displaced in Y ₁ direction, or relatively inner cylinder 22 is displaced in the Y ₂ direction As a result, the main rubber 23 is displaced, thereby absorbing the input vibration.

In the present embodiment, the main rubber 23 is configured such that the short fibers 16 are oriented and compounded in the direction of arrow X in the figure. With this configuration, when low-frequency input vibration is input, the spring constant of the main rubber 23 in the arrow X direction is large, so that the main chamber 24 can be prevented from expanding in the X direction. Therefore, the flow rate of the liquid 27 passing through the orifice groove can be increased, and low frequency vibration can be effectively prevented. When a high-frequency input vibration is input, the main rubber 23 becomes Y ₁ ,
Because the spring constant is small with respect to Y ₂ direction, to absorb high-frequency vibrations in the rubber body 23 itself. Therefore, high-frequency vibration can also be effectively prevented.

FIG. 6 shows a liquid filled vibration isolator 31 which is a modification of the liquid filled vibration isolator 20 shown in FIG. Although the liquid-filled vibration isolator 20 shown in FIG. 5 has the short fibers 16 oriented so as to prevent the main chamber 25 from expanding in the direction of arrow X in FIG. 5, the liquid-filled vibration isolator 31 shown in FIG. The same reference numerals are given to the same components as those of the liquid-filled anti-vibration device 20 shown in Fig. 5. Fig. 6 shows a cross section of the liquid-filled anti-vibration device 31). The short fibers 16 are oriented so as to prevent swelling. With this configuration, the liquid filled vibration isolator 2 shown in FIG.
The same effect as 0 can be obtained. Note that the orientation direction of the short fibers 16 needs to be selected depending on the structure of the liquid-filled vibration isolator, but is generally different from the input direction of the input vibration, more specifically, the direction in which the main chamber 25 is likely to expand. They need to be oriented in the same direction.

[0041]

As described above, according to the present invention, since the spring constant in the direction in which the liquid chamber expands due to the application of the input vibration becomes large, the expansion of the liquid chamber can be prevented.
As a result, the amount of liquid passing through the orifice increases, and vibration in the low frequency region can be prevented. The spring constant of the liquid chamber in the direction corresponding to the input vibration is substantially the same as the inherent spring constant of the elastic body. Since the value is a small value, the elastic body constituting the liquid chamber absorbs vibrations in a high-frequency region, and has features such as effective prevention of vibrations in the high-frequency region.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid filled vibration isolator according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a diagram showing a relationship between a spring constant (K _X ) and a frequency in the X direction in FIG. 1 of the main rubber 2 in a low frequency region, and a relationship between a damping coefficient (C) and a frequency of an input vibration.

FIG. 4 is a diagram showing a relationship between a spring constant (K _X ) and a frequency of the main rubber 2 in the X direction in FIG. 1 in a high frequency region.

FIG. 5 is a longitudinal sectional view of a liquid filled vibration isolator according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a modification of the liquid filled vibration isolator shown in FIG.

[Explanation of symbols]

 1,20,31 Liquid filled vibration isolator 2,23 Main body rubber 3,24 Main room 4 Engine mounting bolt 6 Side plate 7 Bottom plate 8 Fixing member 8a Orifice 9 Rubber film 10,25 Sub chamber 11,27 Liquid 12 Body mounting bolt 13 Vent holes 14, 26 Air chamber 15 Intermediate plate 16 Short fiber 21 Outer tube 22 Inner tube 28 Orifice plate 29 Diaphragm 30 Movable block

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16F 13/00

Claims (1)

(57) [Claims] 1. A pair of liquid chambers in which liquid is sealed are communicated through an orifice, and the liquid passes through the orifice and is interposed between the pair of liquid chambers by a change in volume of the liquid chamber caused by input vibration. In a liquid-filled vibration damping device that generates a damping effect by moving a liquid, a short fiber oriented in a direction that does not coincide with the input vibration is blended with an elastic body that constitutes a part of the liquid chamber. Liquid filled vibration isolator.