JP3458322B2 - 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 isolator used for an engine mount of a vehicle, and more particularly to a liquid filled vibration isolator having a vibration damping characteristic switching means.

[0002]

2. Description of the Related Art Generally, a liquid-filled anti-vibration device is constructed by partitioning a main liquid chamber having a thick rubber elastic body as a chamber wall and a sub liquid chamber having a thin rubber film as a chamber wall by a partition wall. Become. Then, due to the action of the liquid that flows between the two liquid chambers via the throttle passage provided in the partition wall, the vibration corresponding to the low frequency vibration region, mainly engine shake vibration (about 5 to 13 Hz) is attenuated. I am trying to

However, the liquid-filled vibration isolator having the above structure has a problem that the dynamic spring constant becomes high in the vibration region on the higher frequency side, and for example, the vibration isolation effect against idling vibration (about 15 to 35 Hz) is low. It was In order to solve this, a third liquid chamber having a hollow partition wall and an elastic membrane as a chamber wall is provided, and the third liquid chamber and the main liquid chamber act on the higher frequency side than the engine shake vibration. There has been proposed a liquid-filled vibration damping device capable of reducing a plurality of vibrations by communicating with each other through a throttle channel.

Further, the throttle channel for idling vibration is
Usually, the diameter of the flow passage is larger or the length of the flow passage is shorter than that of the throttle flow passage for engine shake vibration. For this reason, there is a type in which a negative pressure chamber is provided on the back surface of the elastic film that constitutes the third liquid chamber so that the vibration damping characteristics can be switched. In this case, when a negative pressure is introduced into the negative pressure chamber, the elastic film is adsorbed on the back surface and movement thereof is restricted.
It is possible to obtain a high damping by restricting the inflow of the liquid into the liquid chamber and forcibly flowing the liquid through the throttle channel to the sub liquid chamber.
When the idle vibration is input, the negative pressure chamber is opened to the atmosphere, so that the elastic film can be elastically deformed and the liquid is caused to flow into the third liquid chamber to reduce the vibration.

[0005]

On the other hand, as a countermeasure against muffled sound vibration (about 60 to 80 Hz) on the higher frequency side than idling vibration, a movable member is provided in the main liquid chamber,
It is known that the displacement of the movable member lowers the hydraulic pressure in the main liquid chamber to absorb and reduce vibration. Further, there is one in which the movable member is provided in the negative pressure chamber. For example, in Japanese Patent Laid-Open No. 4-277338, an elastic restraint member is arranged in the negative pressure chamber to form the third liquid chamber. When a negative pressure is exerted on the elastic body film, the elastic body film is made to adsorb to the elastic restraining member so as to be integrally deformed.

However, in the above-mentioned conventional structure, many constituent members are required for switching the anti-vibration characteristics, and it is necessary to provide a space on the back surface of the elastic constraining member to receive the displacement of the elastic constraining member. There was such a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid-filled anti-vibration device which has a simpler structure, is easier to manufacture, is compact, and has good anti-vibration properties in a wide area.

[0008]

According to a first aspect of the present invention, there is provided a liquid-filled antivibration device which comprises a main liquid chamber having a thick rubber elastic body as a chamber wall and a thin rubber film as a chamber wall. A sub-liquid chamber that faces the chamber with a partition wall between them, and a first throttle channel that reduces the predetermined low-frequency vibration by the action of the liquid that flows through the sub-liquid chamber and the main liquid chamber. An elastic film stretched in the hollow partition wall, a third liquid chamber formed on the elastic liquid film on the main liquid chamber side, and on the sub liquid chamber side of the elastic film. A negative pressure chamber formed so as to adsorb the elastic film to the opposing inner surface of the partition wall by introducing a negative pressure from the outside, the third liquid chamber and the main liquid chamber are communicated with each other. A second throttle channel that operates on a higher frequency side than the first throttle channel is provided. Then, one or more convex portions are formed on both the surface of the elastic film facing the negative pressure chamber and the inner surface of the partition wall, and the elastic body is formed when negative pressure is introduced into the negative pressure chamber. A small space remains between the membrane and the inner surface of the partition wall
By forming it, in the part facing the small space
The elastic film can be minutely displaced .

In the above structure, when a negative pressure is introduced into the negative pressure chamber, the elastic film is attracted to the facing surface and its movement is restricted, but since the small space remains due to the convex portion, The elastic film can be slightly displaced in the portion facing the small space. Therefore, when the muffled sound vibration is input, the vibration can be absorbed by the minute displacement of the elastic film. When a low-frequency shake vibration is input in this state, the movement of the elastic film is restricted, so the liquid in the main liquid chamber flows into the sub liquid chamber via the first throttle channel, Vibration is effectively damped. At the time of input of idling vibration, the negative pressure chamber is opened to the atmosphere so that the elastic film can be freely displaced, and the liquid is caused to flow into the second throttle channel that acts on the higher frequency side to reduce the vibration. Let

As described above, according to the above configuration, it is possible to satisfactorily reduce vibration in different frequency ranges. Moreover,
Since it is not necessary to increase the number of parts only by changing the shape of the existing member, the structure is simpler, the manufacturing is easier, and the size can be made compact.

More specifically, the partition wall is provided between the main body portion having the first throttle channel on the outer peripheral portion and the main body portion provided on the main liquid chamber side of the main body portion. The elastic film that forms the negative pressure chamber, and the third liquid chamber that is disposed between the elastic film and the main liquid chamber to form the third liquid chamber between the elastic film and the main liquid chamber A partition plate provided with a second throttle channel, and the surface of and above the elastic film facing the negative pressure chamber.
On the inner surface of the partition wall, a convex portion is formed at the center of the elastic film.
Forming and forming an annular convex portion on the outer periphery of the main body
However, when a negative pressure is introduced into the negative pressure chamber, the convex portion of the central portion is
The elastic film between the portion and the annular convex portion of the outer peripheral portion
By contacting the inner surface of the partition wall,
Between the elastic film and the inner surface of the partition wall, respectively.
The small space remains in the
The elastic membrane can be displaced minutely at the
And are characterized.

Further, a standing wall projecting toward the body portion is formed on the outer peripheral edge of the elastic film, and a projecting end surface of the standing wall is fixed on an annular convex portion formed on an outer peripheral portion of the body portion. If the elastic film is brought into close contact with the annular convex portion of the main body portion only at the projecting end face ( claim 2 ), the small space can be easily formed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. In FIG. 1 (a),
Reference numeral 1 denotes a thick rubber elastic body having a hollow lower half portion as a main liquid chamber A. A partition wall 2 is disposed at the lower end opening of the rubber elastic body 1 so as to close it, and a thin rubber film 3 is disposed below the partition wall 2, and the partition wall 2 and the rubber film 3 are provided. A space surrounded by is defined as a sub liquid chamber B.

A cylindrical body fitting 4 is joined to the outer periphery of the lower half of the rubber elastic body 1. The lower end edge of the main body fitting 4 extends downward along the outer peripheries of the partition wall 2 and the rubber film 3 and is further bent inward to hold them. A connecting member 11 is embedded and fixed in the upper portion of the rubber elastic body 1, and is connected to the engine by the connecting member 11. A cap 5 is attached to the upper half of the rubber elastic body 1, and is fixed to the vehicle body by a plurality of legs 51 (see FIG. 2) provided on the side of the cap 5. There is.

As shown in FIG. 2, the partition wall 2 includes a substantially container-shaped main body 21 made of an aluminum casting or a resin integrally molded product, and an elastic film 22 and a partition plate 23 held therein. Become. The main body 21 has a thick outer peripheral portion and is provided with an arcuate groove 21a that opens downward, and the first diaphragm is provided between the main body 21 and the outer peripheral portion 31 of the rubber film 3 disposed below. The flow path S1 (see FIG. 1) is formed. Here, in the outer peripheral portion 31 of the rubber film 3,
A tubular reinforcing member is joined, and the upper end of the tubular reinforcing member is joined to the groove 2
It has a flange shape along the bottom of 1a.

The main body portion 21 is provided with a communication hole 21b for communicating the first throttle channel S1 with the main liquid chamber A, and the first throttle channel S1 and the secondary liquid are provided at positions not shown. It has a communication hole communicating with the chamber B. Then, the main liquid chamber A and the sub liquid chamber B are passed through the first throttle channel S1.
By circulating the liquid between the flow path and the flow path, vibration in a predetermined frequency range set by the flow path diameter and flow path length, for example, engine shake vibration is reduced.

The elastic film 22 is made of an elastic member such as rubber and is formed to have a thickness slightly larger than that of the rubber film 3. A cylindrical metal member 22a is fixed to the outer periphery of the elastic film 22, and the metal member 22a is fitted and fixed in the main body 21. The upper edge of the metal member 22a is bent outward and is in contact with the upper surface of the main body 21. The space formed between the elastic body film 22 and the main body portion 21 is a negative pressure chamber C, and the elastic body membrane is formed by introducing a negative pressure from a negative pressure passage 21c provided in the main body portion 21. 22 can be sucked downward.

The negative pressure passage 21c communicates with a negative pressure pipe 21d projecting to the side of the main body portion 21, and the negative pressure pipe 21d communicates with a negative pressure passage of an engine, so that the negative pressure chamber C is negatively connected. Pressure can be introduced. In addition, of the main body metal fitting 4,
At the lower end where the rubber elastic body 1 is not joined, cutouts 41 are formed at a plurality of positions in the circumferential direction.
Is provided so as to correspond to one of the notches 41 of the main body metal fitting 4 so that the negative pressure pipe 21d can be taken out at the same time as the assembling. Further, a plurality of protrusions 21e provided on the side of the body portion 21 correspond to the other cutout portions 41 of the body metal fitting 4, respectively, which facilitates alignment during assembly.

The partition plate 23 has an annular space serving as the second throttle channel S2 on the outer peripheral portion thereof, and has a downwardly projecting flange 23a at the outer peripheral edge of the lower surface.
It is adapted to be fitted and held in 2a. As a result, a third gap is formed between the partition plate 23 and the elastic film 22.
The liquid chamber D is formed (see FIG. 1). The second throttle channel S2 is formed to have a channel diameter larger or a channel length shorter than that of the first throttle channel S1, so that the first throttle channel S2 is formed.
It is adjusted so as to absorb vibrations on the higher frequency side than 1, for example, idling vibrations. The second throttle channel S2 communicates with the main liquid chamber through the communication hole 23b, and also communicates with the auxiliary liquid chamber B through a communication hole provided at a position not shown.

At the center of the elastic film 22, there is formed a convex portion 22b protruding upward and downward, and the convex portion 22b is
Both end surfaces are in close contact with the upper surface of the main body 21 and the lower surface of the partition plate 23, respectively (FIG. 1). Further, a standing wall 22c protruding downward is formed on the outer peripheral edge of the elastic film 22. On the outer peripheral portion of the main body portion 21,
An annular convex portion 21f is provided, and the lower end surface of the standing wall 22c is brought into close contact with the upper surface of the annular convex portion 21f. By providing the convex portion 22b and the annular convex portion 21f, it becomes easy to form a space between the elastic film 22 and the main body portion 21. The standing wall 22c reinforces the elastic film 22 and at the same time facilitates the formation of a space between the standing wall 22c and the body portion 21.

In the above structure, when a negative pressure is introduced into the negative pressure chamber C, as shown in FIG.
2 is sucked down. However, the elastic body film 22 and the main body portion 21 do not completely adhere to each other, and the convex portion 2 in the central portion
A small space 6 remains around the circumference 2b and between the annular convex portion 21f on the outer peripheral portion and the standing wall 22c. Therefore, in the portion facing the small space 6, the elastic film 22 can be slightly displaced, so that the rigidity of the elastic film 22 and the volume of the small space 6 at the time of negative pressure are appropriate. By doing so, muffled sound vibration can be effectively absorbed. Normally, -200 to -500 mmHg obtained when the vehicle is running
The contact area between the elastic film 22 and the main body 21 at the time of negative pressure is about 40 to 95% of the movable area at the time of introducing the atmosphere (shown by the dotted line in FIG. 1B). Is good.
Further, at this time, since the free deformation of the elastic film 22 is restricted, when the engine shake vibration is input, the liquid flows into the sub liquid chamber B which is more easily deformed and the vibration is damped.

This will be described with reference to the frequency characteristic diagrams of FIGS. FIG. 3 shows a case where the elastic film 22 and the main body portion 21 do not have a convex portion, and when a negative pressure is applied, a small space does not remain in the negative pressure chamber C, so the elastic film 22 functions as a rigid body. . In this case, as shown by the solid line in the figure, a high damping coefficient is obtained in the vicinity of about 10 Hz corresponding to the engine shake vibration due to the action of the liquid flowing through the first throttle channel S1, but on a higher frequency side than this. The dynamic spring constant is high, and the vibration reduction effect cannot be obtained. The dotted line in the figure shows the case where the negative pressure chamber C is communicated with the atmosphere, and the free deformation of the elastic film 22 enables the liquid to flow into the third liquid chamber D. Then, due to the action of the liquid flowing through the second throttle channel S2, the dynamic spring constant near approximately 30 Hz corresponding to idling vibration becomes low, but the dynamic spring constant becomes higher on the higher frequency side, and the vibration reducing effect is obtained. Can't get

FIG. 4 is a characteristic diagram when negative pressure is introduced in the structure of the present invention in which the elastic film 22 and the main body 21 are provided with the convex portions 22b and 21f and the standing wall 22c. At this time, the elastic film 22 has a sufficiently high rigidity, and the inflow of the liquid into the third liquid chamber D is regulated.
When the engine shake vibration near 0 Hz is input, good vibration damping is achieved by the action of the liquid flowing through the first throttle channel S1. Also, about 6 for muffled sound vibration
In the vicinity of 0 to 80 Hz, the elastic body membrane 22 can be finely displaced by the small space 6 formed between the elastic body membrane 22 and the main body portion 21 to absorb an increase in the internal pressure of the main liquid chamber. Vibration is reduced by lowering the dynamic spring constant. When inputting idling vibration, the negative pressure chamber C
By introducing the atmosphere into the, the dynamic spring constant can be reduced and the vibration can be reduced, as in the case of FIG. 3 (dotted line).

As described above, according to the above structure, a simple structure can provide good vibration damping characteristics and is highly practical. In addition,
In the present invention, the number of the above-mentioned convex portions, the installation position, etc. are not limited to those shown in the above-mentioned embodiment, but can be changed appropriately.

[Brief description of drawings]

1A is an overall sectional view of a liquid filled vibration damping device of the present invention, and FIG. 1B is a partially enlarged sectional view thereof.

FIG. 2 is an exploded cross-sectional view of the liquid filled vibration damping device of the present invention.

FIG. 3 is a diagram showing frequency characteristics of a conventional liquid filled vibration damping device.

FIG. 4 is a diagram showing frequency characteristics of the liquid filled vibration damping device of the present invention.

[Explanation of symbols]

1 rubber elastic body 2 partition walls 21 Body 21f Annular convex portion (convex portion) 22 Elastic body membrane 22b convex part 22c standing wall 23 Partition Board 3 rubber film 4 body fittings 5 caps A main liquid chamber B Sub liquid chamber C negative pressure chamber D Third liquid chamber S1 First throttle channel S2 Second throttle channel

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadaki Shimoda 1 Ochiai, Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Within Toyoda Gosei Co., Ltd. Address within Toyoda Gosei Co., Ltd. (56) Reference JP 5-118377 (JP, A) JP 5-44767 (JP, A) JP 8-247209 (JP, A) JP 4-277338 (JP, A) Actual Kaihei 5-27380 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16F 13/26

Claims (2)

(57) [Claims] 1. A main liquid chamber having a thick rubber elastic body as a chamber wall, a sub liquid chamber having a thin rubber film as a chamber wall and facing the main liquid chamber with a partition wall therebetween, and the sub liquid chamber. A first throttle channel for reducing a predetermined low frequency vibration by the action of a liquid that flows through the main fluid chamber and the main fluid chamber, and an elastic film stretched in the hollow partition wall. A third liquid chamber formed on the main liquid chamber side of the elastic film and a second liquid chamber formed on the sub liquid chamber side of the elastic film are opposed to each other by introducing a negative pressure from the outside. A second throttle flow that communicates the negative pressure chamber adapted to be adsorbed to the inner surface of the partition wall, the third liquid chamber and the main liquid chamber, and acts on the higher frequency side than the first throttle channel. A liquid-filled anti-vibration device including a channel, the book having the partition wall and the first throttle channel provided on an outer peripheral portion thereof.
A body and the body provided on the main liquid chamber side of the body
And the elastic film that forms the negative pressure chamber between the elastic film and the elastic film.
Between the elastic body film and the main body fluid chamber
The third liquid chamber is formed between the
A partition plate provided with a passage, and a convex portion is formed in the central portion of the elastic film on the surface of the elastic film facing the negative pressure chamber and the inner surface of the partition wall .
At the same time, an annular convex portion is formed on the outer peripheral portion of the main body portion, and when a negative pressure is introduced into the negative pressure chamber, the convex portion on the central portion and the upper portion
The elastic film between the outer peripheral portion and the annular convex portion is the partition wall.
When contacting the inner surface,
A small space is left between the elastic film and the inner surface of the partition wall, so that the elastic film can be finely displaced in the portion facing the small space. Anti-vibration device. 2. An outer wall of the elastic film is formed with a standing wall projecting toward the main body, and a projecting end surface of the standing wall is fixed on an annular convex portion formed on an outer peripheral portion of the main body. the elastic membrane only on the projecting end face liquid-sealed vibration isolating device according to claim 1, wherein so as to close contact with the annular projection of the body portion.