JPH1038013A - Fluid-sealed vibration control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the vibration with a different frequency effectively by partitioning a balance room in to a balance room near an inner cylinder and a balance room near an outer cylinder across a vibration input direction in series by a rubber elastic partition having a higher rigidity than a bottom wall and communicating respective balance rooms with a pressure receiving room and a connecting passage respectively. SOLUTION: A balance room 18 is partitioned to a first balance room 18a and a second balance room 18b by a rubber elastic partition 28 and both balance rooms are arranged in series in a vibration input direction. A pressure receiving room 20 is connected with the first balance room 18a by a first connection passage 22a and with the second balance room 18b by a second connection passage 22b. A fluid resistance value is set so that the former is larger than latter by minimizing the sectional area of the first connection passage 22a and enlarging a flow passage length and enlarging the sectional area of the second connection passage 22b and shortning the flow passage length. The resonance peak of a loss coefficient is appeared by two and the vibration from a low frequency vibration upto a high frequency vibration is reduced effectively by connecting each to the pressure receiving room by an exclusive connection passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid filled type vibration damping device suitable for use in a cabin mount or the like for damping vibration of a cabin due to engine vibration.

[0002]

2. Description of the Related Art A fluid-filled type vibration damping device in which a plurality of incompressible fluid-filled fluid chambers are connected to a rubber elastic body as a vibration receiving medium by a communication passage is provided only by the rubber elastic body due to the resonance action of the fluid. It is known that there is an excellent anti-vibration effect which cannot be obtained by the anti-vibration device of the above. In this case, in order to enhance the damping and vibration damping effects, the fluid chamber is usually composed of an equilibrium chamber in which a part of the constituent wall can be easily deformed, and a pressure receiving chamber that is hardly deformed.

[0003] By the way, the vibration of an engine in a vehicle includes shake vibration having a frequency of 15 Hz or less generated during running, muffled noise of around 100 Hz, and idle vibration of about 20 to 40 Hz generated during idling operation. Therefore, if one fluid transfer system including the fluid chamber and the communication passage is set as one, each vibration cannot be effectively prevented.

For this reason, there has been proposed an apparatus in which a plurality of fluid moving systems are formed so as to derive a resonance phenomenon of a fluid at different frequencies. In response to this request, the present applicant has proposed a case in which the pressure receiving chamber is serially partitioned by a rubber elastic partition wall before and after the vibration input direction in Japanese Patent Application No. 7-193996.

[0005]

In order to partition the pressure receiving chamber in this way, the pressure receiving chamber must have a corresponding space. However, in a cabin mount or the like that supports a truck cabin, the diameter of the inner cylinder is considerably large, and the thickness of the inner wall is increased by projecting a component wall toward the pressure receiving chamber to support a heavy weight. Therefore, the volume is insufficient. SUMMARY OF THE INVENTION The present invention is to provide a vibration isolator capable of overcoming such problems and effectively reducing vibrations having different frequencies.

[0006]

SUMMARY OF THE INVENTION Under the above-mentioned problems, the present invention provides an outer cylinder having an outer cylinder, which is located on one side in the vibration input direction with the inner cylinder sandwiched between an inner cylinder and an outer cylinder arranged in parallel. Uncompressed enclosed by a thin rubber elastic bottom wall facing the outer end of the space formed to the outside air, and a rubber elastic side wall bridged between both ends of the rubber elastic bottom wall and the outer cylinder. Equilibrium chamber filled with sexual fluid,
On the other side, a rubber elastic partition wall facing the inner end of the space including the inner cylinder and a rubber elastic side wall bridged between both ends of the rubber elastic partition wall and the outer cylinder. In a fluid-filled type vibration isolator in which a pressure receiving chamber in which a compressive fluid is sealed is formed, and these equilibrium chambers and the pressure receiving chambers are communicated with each other through a communication passage, the equilibrium chamber has higher rigidity than the rubber elastic bottom wall. In series with the rubber elastic partition wall in series before and after the vibration input direction, the first equilibrium chamber closer to the inner cylinder and the second equilibrium chamber closer to the outer cylinder are partitioned, and the first equilibrium chamber and the pressure receiving chamber are separated. A fluid-filled type vibration damping device is provided, wherein the first communication passage and the second equilibrium chamber and the pressure receiving chamber are communicated with each other through the second communication passage.

Further, according to the present invention, in the above means, the flow resistance value of the first communication passage is made larger than that of the second communication passage, and the rubber elastic partition wall is connected to the rubber elastic side wall. provide.

When the present invention employs the above measures, that is, since the thin rubber elastic bottom wall of the first equilibrium chamber is easily elastically deformed, when a large-amplitude low-frequency vibration such as a shake vibration is input. The fluid preferentially flows through the first communication passage, and the resonance action attenuates the vibration. At this time, the damping effect is further increased by increasing the flow resistance value of the first communication passage.

[0009] On the other hand, when medium amplitude and high frequency vibrations of small amplitude such as idle vibration and muffled sound are input, the first communication passage is substantially closed and the fluid transfer system is stuck. Is small and the vibration acceleration increases,
The rubber elastic partition wall of the second equilibrium chamber is deformed. Therefore, the fluid flows through the second communication passage, and the resonance action at this time suppresses an increase in the dynamic spring constant to prevent the vibration.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a fluid filled type vibration damping device (with an outer cylinder removed) showing an example of the present invention, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a front view of the fluid filled type vibration damping device.

The anti-vibration device of the present embodiment has an inner cylinder 1 arranged in parallel.
A thin rubber elastic bottom wall facing the outer end of a space 24 formed outside of the inner cylinder 10 and communicating with the outside air, on one side in the vibration input direction between the inner cylinder 10 and the outer cylinder 12. An incompressible fluid enclosed by a bottom wall 26 (hereinafter, referred to as a bottom wall) and a rubber elastic side wall (hereinafter, referred to as a side wall) 14 bridged between both ends of the bottom wall 26 and the outer cylinder 12 is sealed. An equilibrium chamber 18 is formed.

A rubber elastic partition wall (hereinafter, referred to as an inner wall) including the inner cylinder 10 and facing the inner end of the space portion 24 on the other side in the vibration input direction.
A pressure receiving chamber 2 filled with the same incompressible fluid surrounded by a rubber elastic side wall (hereinafter referred to as a side wall) 15 bridged between both ends of the partition 16 and the outer cylinder 12.
0 are formed, and the equilibrium chamber 18 and the pressure receiving chamber 20 are communicated with each other through the communication passage 22.

In the present invention, the balance chamber 18 is partitioned into a first balance chamber 18a and a second balance chamber 18b by a rubber elastic partition wall (hereinafter, referred to as a partition wall) 28. The two equilibrium chambers 18a and 18b are arranged in series in the vibration input direction, and the side closer to the inner cylinder 10 is the first equilibrium chamber 18a and the outer cylinder 1
The side closer to 2 is the second equilibrium chamber 18b. This is to make the vibration input act on the change in the volume of the equilibrium chamber 18 to the maximum.

The partition wall 28 has considerable rigidity, that is, the bottom wall 2.
It has a rigidity higher than 6, and is not deformed by fluid movement during low-frequency vibration. For this reason, it is preferable that the partition wall 28 be provided continuously with the side wall 15. It is also conceivable that a metal body other than rubber, for example, is put in the partition wall 28. This is because the strength of the partition wall 28 is increased, and an effect as a dynamic damper during vibration can be expected.

Further, the partition wall 28 also serves as a stopper for preventing the inner cylinder 10 and the outer cylinder 12 from approaching abnormally when the equilibrium chamber 18 contracts. Also, a rubber elastic mass 30 is provided near the outer cylinder 12 inside the pressure receiving chamber 20, which prevents the inner cylinder 10 and the outer cylinder 12 from approaching abnormally when the pressure receiving chamber 20 contracts. It becomes a stopper to prevent.

The equilibrium chamber 18 and the pressure receiving chamber 20 are connected to a communication passage 22.
Will be contacted at In this case, the first equilibrium chamber 18a is the first communication passage 22a, and the second equilibrium chamber 18b is the second communication passage 2a.
You will be contacted at 2b. In this example, the communication passages 22a and 22b are formed using the communication passage forming body 32 which is a separate member.

FIG. 4A shows the communication passage forming body 32 in FIG.
FIG. 5 is a view taken in the direction of the arrow B in FIG. 3, and this communication passage forming body 32 is made of metal, resin, rubber, or the like having the first communication passage 22a and the second communication passage 22b formed on the outer periphery. This is a semi-circular ring having a structure in which it is fitted over the equilibrium chamber 18 and the pressure receiving chamber 20 around its outer periphery.

In this case, openings 22aa and 22ab communicating with the first equilibrium chamber 18a and the pressure receiving chamber 20 are formed at both ends of the first communication passage 22a.
Openings 22ba, 22bb communicating with the second equilibrium chamber 18b and the pressure receiving chamber 20 are also formed at both ends of 2b. The first communication passage 22a in this example has a small cross-sectional area, has a long passage length due to meandering or the like, and has a second communication passage 22b.
Has a large cross-sectional area and a short flow path length. That is,
The flow resistance value (flow path length / cross-sectional area) is set larger in the former than in the latter.

In addition to the above, the side walls 14, 1 near the outer cylinder 12
A metal ring 34 in which the openings of the equilibrium chamber 18, the pressure receiving chamber 20, and the communication passages 32 are cut like windows is wound around the partition wall 5, the partition 16, and the like. This is for increasing the strength and increasing the rigidity of the entire cylinder.

As described above, for example, if the outer cylinder is fixed to the chassis and the cabin or the like is supported by the inner cylinder, the vibration of the engine is prevented from being transmitted to the cabin by the resonance action of the fluid transfer system and the spring action of the rubber elastic body. it can. At this time, the equilibrium chamber is divided into two parts, each of which is connected to the pressure receiving chamber by a dedicated communication passage, so that two resonance peaks of the loss coefficient appear, effectively reducing low frequency vibration to high frequency vibration. I do.

In this case, due to the rigidity of the partition wall of the equilibrium chamber, the fluid between the pressure receiving chamber and the equilibrium chamber preferentially travels through the first communication passage against low-frequency vibration such as shake vibration. This vibration is attenuated by the resonance action of the fluid transfer system. The damping effect is further enhanced by setting the flow resistance value of the first communication passage large.

With respect to the medium-frequency vibration of idle vibration or muffled noise, the partition wall of the equilibrium chamber is deformed this time based on an increase in vibration acceleration and the like. Is absorbed by further deforming the wall),
Fluid flowing between the two chambers flows through the second communication passage, and the resonance action suppresses an increase in the dynamic spring constant and dampens this vibration.

FIG. 6 shows the frequency characteristics of the anti-vibration support device of the present invention showing the above-described anti-vibration phenomenon. First, a first resonance peak of the loss coefficient appears in a low frequency range, and then in a high frequency range. A second resonance peak appears. The first resonance peak is due to the first balance chamber and the first communication passage having a large flow resistance value, and the second resonance peak is due to the second balance chamber and the second communication passage having a small flow resistance value. is there.

The first resonance peak value is set to be small and the second resonance peak value is set to be large in order to suppress the dynamic spring constant in the mid-high frequency range.
This is for reliably damping idle vibrations and muffled sounds.

[0025]

As described above, it is possible that the fluid must be sharply and sufficiently flowing between the equilibrium chamber and the pressure receiving chamber during vibration, as described above. The partition walls are divided before and after the vibration input direction, and the partition walls have considerable rigidity. Also, the partition walls are connected to each other, or the flow resistance value of the communication passage leading to the pressure receiving chamber and each equilibrium chamber is changed. The above-described measures of the present invention contribute to ensuring that this is achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fluid filled type vibration damping device showing an example of the present invention.

FIG. 2 is a longitudinal sectional view of a fluid filled type vibration damping device showing an example of the present invention.

FIG. 3 is a front view of a fluid filled type vibration damping device showing an example of the present invention.

FIG. 4 is a view taken in the direction of arrow A in FIG. 3;

FIG. 5 is a view taken in the direction of arrow B in FIG. 3;

FIG. 6 is a frequency characteristic of the fluid-filled vibration isolator showing one example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Inner cylinder 12 Outer cylinder 14 Rubber elastic side wall 15 Rubber elastic side wall 16 Rubber elastic side wall 18 Equilibrium chamber 18a First equilibrium chamber 18b Second equilibrium chamber 20 Pressure receiving chamber 22 Communication passage 22a First communication passage 22b Second communication passage 24 Space 26 Rubber elastic bottom wall 28 Rubber elastic partition wall

Claims (3)

[Claims] 1. An outer end of a space formed outside the inner cylinder and communicating with outside air, on one side in front and rear of the vibration input direction with the inner cylinder interposed between the inner cylinder and the outer cylinder arranged in parallel. And a balance chamber filled with an incompressible fluid surrounded by a thin rubber elastic bottom wall facing the front end, and rubber elastic side walls bridged between both ends of the rubber elastic bottom wall and the outer cylinder. The same incompressible fluid surrounded by a rubber elastic partition wall facing the inner end of the space including the inner cylinder and a rubber elastic side wall bridged between both ends of the rubber elastic partition wall and the outer cylinder. In a fluid-filled type vibration damping device in which a sealed pressure receiving chamber is formed, and the equilibrium chamber and the pressure receiving chamber are communicated with each other through a communication passage, a rubber elastic partition wall having higher rigidity than a rubber elastic bottom wall. The first equilibrium chamber on the side closer to the inner cylinder and the second equilibrium chamber on the side closer to the outer cylinder are divided in series before and after the vibration input direction. A fluid filled type vibration damping device, wherein the first equilibrium chamber and the pressure receiving chamber are communicated with each other through a first communication passage, and the second equilibrium chamber and the pressure receiving chamber are communicated with each other through a second communication passage. 2. A flow resistance value (flow path length / cross-sectional area) of the first communication passage is larger than that of the second communication passage.
The fluid filled type vibration damping device as described in the above. 3. The fluid filled type vibration damping device according to claim 1, wherein the rubber elastic partition wall is continuous with the rubber elastic side wall.