JPH08277878A - Liquid-filled vibration control device - Google Patents

Abstract

PURPOSE: To realize a liquid-filled vibration control device displaying an excellent vibration absorbing characteristic in both low and high frequency areas with simple structure. CONSTITUTION: A main liquid chamber A with a thick-walled vibration-proof rubber body 1 as the chamber wall, and an auxiliary liquid chamber B with a thin-walled rubber film 2 as the chamber wall are partitioned by a partition plate 3, and the main liquid chamber A and the auxiliary liquid chamber B are communicated with each other by a throttle passage 31. A plurarity of foam bodies 41, 42 containing a large number of mutually independent blowholes and having internal pressure absorbing action in the main liquid chamber A are disposed at different expansion ratios inside the main liquid chamber A. Micro amplitude vibration of high frequency is absorbed by the foam body 41 with a high expansion ratio, and large amplitude vibration of low frequency is absorbed by the foam body 42 with a low expansion ratio.

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 used as an engine mount of a vehicle.

[0002]

2. Description of the Related Art In general, a liquid-filled type vibration damping device has a main liquid chamber having a thick vibration-proof rubber body as a chamber wall and a thin rubber film as a chamber wall, and the main liquid chamber and the partition plate are It is composed of a sub liquid chamber. Then, a large damping force is exerted particularly in a low frequency region (engine shake vibration around 10 to 15 Hz, for example) due to the fluid resistance when the enclosed liquid is circulated in the throttle channel that connects these two liquid chambers (FIG. 4). (A)
reference).

By the way, as a dynamic characteristic of the liquid-filled vibration isolator, it is preferable to reduce the dynamic spring constant in order to absorb the vibration at a high frequency side, for example, in the range of 100 to 200 Hz. However, as shown by the solid line in FIG. 4 (B), in the above-described conventional device, it becomes difficult for the liquid to flow to the throttle channel in the high frequency region, so that the internal pressure of the main liquid chamber rises and only the main body rubber is discharged. The dynamic spring constant tends to be higher than in the case (dotted line in the figure). Therefore, a part of the partition plate for partitioning the main liquid chamber and the sub liquid chamber is formed of a rubber film, or a rubber film is sandwiched between two partition plates having through holes on the plate surface, and the rubber film is displaced. Absorbs the rise in main liquid chamber pressure,
A device having a reduced dynamic spring constant has been proposed (dotted line in the figure).

[0004]

However, in the former case, since the rubber film is displaced in proportion to the change in the internal pressure of the main liquid chamber, the action of the throttle channel in the low frequency region is hindered, and the high damping force cannot be secured. There is a risk. In the latter, the rubber film can be operated only in a desired frequency range by controlling the clearance between the partition plate and the rubber film, but the partition plate configuration is complicated and the number of parts is large, or There are problems that the rubber film deteriorates with time, the clearance changes, and rattling occurs.

Therefore, an object of the present invention is to realize a liquid filled vibration damping device having a simple structure and exhibiting excellent vibration absorption characteristics in the low frequency and high frequency regions.

[0006]

FIG. 1 shows the structure of a liquid filled vibration damping device according to the present invention for solving the above problems. A main liquid chamber A having a thick vibration damping rubber body 1 as a chamber wall is shown. , Thin rubber film 2
A sub-liquid chamber B having a chamber wall as a partition wall is partitioned by a partition plate 3, and the main liquid chamber A and the sub-liquid chamber B are connected to each other by a throttle channel 31. In the main liquid chamber A, a foamed body 41 containing a large number of air bubbles independent of each other and having an action of absorbing internal pressure in the main liquid chamber,
A plurality of 42 are arranged by changing the expansion ratio (Claim 1). Alternatively, as shown in FIG. 3, the foaming ratio of the foam 4 may be partially changed (claim 2). Also,
A stopper 13 that restricts the movement of the foams 41 and 42 may be provided in the main liquid chamber A (FIG. 1, claim 3).

[0007]

In the structure of claim 1, the foams 41 and 42 arranged in the main liquid chamber A contain a large number of bubbles which are independent of each other, and when the internal pressure of the main liquid chamber A rises, they are present in the bubbles. The gas that contracts contracts the bubbles and absorbs the change in internal pressure.
At this time, since the foams 41 and 42 act at the internal pressure according to the foaming ratio, the foam 41 having a high foaming ratio that acts when a high-frequency minute amplitude vibration and the low-frequency large-amplitude vibration act. By installing the foamed body 42 having a low foaming ratio in the main liquid chamber A, it is possible to effectively absorb vibration in different regions.

That is, generally, the higher the expansion ratio of the foam, the lower the hydraulic pressure, so that it works on the high frequency side of the minute amplitude. Therefore, by using the foam 41 having a high expansion ratio, the dynamic spring constant in the high frequency region can be reduced, and the vibration in the high frequency region can be effectively reduced. However, since the damping force in the low frequency region tends to decrease, by using the foamed substance 42 having a low expansion ratio acting in the low frequency region in addition to the foamed substance 41 having a high expansion ratio,
It secures high damping force in the low frequency range and exhibits excellent vibration absorption characteristics in a wide range.

This is also the case with the structure in which a single foam body 4 is used and the expansion ratio is partially changed, as in claim 2.
It is possible to easily obtain a desired vibration absorption characteristic without changing the basic structure of the device. Further, when the stopper 13 is provided to restrict the movement of the foams 41 and 42 as in the third aspect, the problem that the foams 41 and 42 close the inlet of the throttle channel 31 does not occur.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a first embodiment of the present invention, in which a thick vibration-proof rubber body 1 is
A main liquid chamber A is formed in the hollow lower half portion. A thin rubber film 2 is arranged below the antivibration rubber body 1 so as to close its lower end opening, and a sub liquid chamber B is formed above the rubber film 2. The main liquid chamber A and the sub liquid chamber B are
It is partitioned by a metallic partition plate 3 arranged above the rubber film 2.

A metal side plate 5 is joined to the outer periphery of the vibration-proof rubber body 1. On the other hand, the rubber film 2 is supported by a container-shaped metal bottom plate 6 arranged below, and the outer peripheral edges of the rubber film 2 and the bottom plate 6 are in the lower end portion of the side plate 5 together with the outer peripheral edge of the partition plate 3. It is pinched. An annular groove is formed on the outer periphery of the partition plate 3, and the anti-vibration rubber body 1 and the annular groove are formed.
The annular space formed by and is used as the throttle channel 31.
The throttle channel 31 communicates with the main liquid chamber A and the sub liquid chamber B through a communication hole (not shown) provided in the partition plate 3. Further, a bolt 11 connected to a vibration body such as an engine is provided on the upper surface of the vibration-proof rubber body 1, and a bolt 61 connected to the vehicle body is provided on the bottom surface of the bottom plate 6 so as to stand.

The anti-vibration rubber body 1 is formed by recessing a part of the wall surface of the main liquid chamber A, and a plurality of foam bodies 41, 42 are arranged in the recess portion 12. These foams 41,
42 contains a large number of air bubbles independent of each other,
The bubbles are crushed when the internal pressure of the main liquid chamber A rises, and the change in the internal pressure is absorbed. Generally, the higher the expansion ratio, the higher the frequency of the absorbed vibration. Here, the foam 41 is set as a high expansion ratio to absorb high-frequency minute amplitude vibrations, and the foam 42 is set as a low expansion ratio and a large low frequency. It is designed to absorb amplitude vibrations. In order to secure the damping force during the engine shake, it is preferable that the volume of the foam body 42 having a low foaming ratio is larger than that of the foam body 41 having a high foaming ratio. Further, the variable volume ΔV of the foam 41 and the main liquid chamber A associated with the displacement at high frequency amplitude
It is more preferable to set the volume change amount ΔV ′ of 1 to a close value because it is possible to minimize the decrease in the damping force.

As the material of the foams 41 and 42, a material having a heat resistant temperature of at least 130 ° C. or higher is desirable, and a rubber material or a resin material which is excellent in solvent resistance and hard to permeate gas is preferable. . Specific examples include EPDM and butyl rubber.

The concave portion 12 has a lower end edge extending inward to form a stopper 13, and the foam body 4 is formed.
The movements of 1 and 42 are restricted within the recess 12. Therefore, there is no risk that the filled liquid will be sucked into the inlets of the throttle flow passages 31 of the foams 41 and 42 by the negative pressure when flowing through the throttle flow passage 31, and the flow of the filled liquid will not be hindered.

In the above structure, when a high-frequency minute amplitude vibration is input, the foam 41 having a high expansion ratio absorbs the change in the internal pressure in the main liquid chamber A to reduce the dynamic spring constant and absorb the vibration. On the other hand, when a low-frequency large-amplitude vibration is input, the damping coefficient tends to slightly decrease only with the foam body 41 having a high foaming ratio, but the foam body 42 having a low foaming ratio causes a change in internal pressure in the main liquid chamber A. It is possible to absorb the vibration, secure a high damping force, and effectively absorb the vibration.

2 (A) and 2 (B) show the low-frequency characteristics and high-frequency characteristics of the liquid-filled anti-vibration device having the above-mentioned structure in comparison with the conventional device. Here, FIG. 2 (A) is a characteristic diagram in the case of constant amplitude excitation, and FIG. 2 (B) is a characteristic diagram in the case of constant acceleration excitation. In the low frequency region of FIG. 2 (A), the device of the present invention using two types of foam having a low expansion ratio and a high expansion ratio (one-dot chain line in the figure) is
A damping force equivalent to that of a conventional device (solid line in the figure) in which a partition plate is provided with a rubber film is secured. On the other hand, in the high frequency region of FIG. 2B, due to the action of the foam body 41 having a high expansion ratio, compared with the conventional device provided with the rubber film or only the foam body 42 having a low expansion ratio (dotted line in the figure). Further, the dynamic spring constant is reduced, and it is possible to obtain a low dynamic spring constant closer to that in the case where only the main body rubber is used (see FIG. 4).

Thus, with a simple structure, a good vibration reducing effect can be obtained in a wide frequency range. Since the frequency region in which the foam acts varies depending on the expansion ratio, volume, etc., the characteristics can be easily tuned by appropriately adjusting these in accordance with the required characteristics.

FIG. 3 shows a second embodiment of the present invention. In the above embodiment, the plurality of foam bodies 41 having different expansion ratios,
Although 42 is used, a foam 4 having a partially different expansion ratio may be used as shown in FIG. 2, and the same effect can be obtained.
Here, the foamed body 4 is molded so that the center portion 41 has a high foaming ratio and the outer peripheral portion 42 has a low foaming ratio. In addition, in this embodiment, a dish-shaped metal stopper plate 7 is arranged along the upper wall of the main liquid chamber A, and the lower end edge thereof is bent inward to form the stopper 71, and the foam 4 is formed. Holds inside. In the normal state, the stopper plate 7 is located slightly away from the vibration-proof rubber body 1, and when a large vibration is input, its upper surface abuts on the vibration-proof rubber body 1 so as to suppress further deformation. However, if the foam body 4 is held by using a known member as described above, it is not necessary to increase the number of parts or change the device configuration.

[0019]

According to the present invention, a plurality of closed-cell foams having different expansion ratios are provided in the main liquid chamber, or the expansion ratio of the foams is partially changed, so that the structure is simpler than the conventional one. The dynamic spring constant in the high frequency range can be greatly reduced. Therefore, it is possible to easily realize the liquid-filled anti-vibration device having excellent vibration absorption characteristics in the low frequency and high frequency regions.

[Brief description of drawings]

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

FIG. 2 is a diagram comparing the vibration absorption characteristics of the liquid-filled vibration damping device of the present invention with a conventional device, FIG.
(B) is a high frequency characteristic diagram.

FIG. 3 is an overall sectional view of a liquid filled vibration damping device according to a second embodiment of the present invention.

4A and 4B show vibration absorption characteristics of a conventional device, where FIG. 4A is a low frequency characteristic diagram and FIG. 4B is a high frequency characteristic diagram.

[Explanation of symbols]

 A main liquid chamber B sub liquid chamber 1 anti-vibration rubber body 12 recess 13 stopper 2 rubber film 3 partition plate 31 throttle channel 4 foam 41, 42 foam 5 side plate 6 bottom plate 7 stopper plate 71 stopper

Claims (3)

[Claims] 1. A main liquid chamber having a thick anti-vibration rubber body as a chamber wall and a sub liquid chamber having a thin rubber film as a chamber wall are partitioned by a partition plate, and these liquid chambers are squeezed and flow passaged. In the liquid-filled anti-vibration device that has been communicated with each other, a plurality of foams that contain a large number of independent air bubbles in the main liquid chamber and have an internal pressure absorbing action in the main liquid chamber are arranged at different expansion ratios. A liquid filled vibration damping device characterized by the above. 2. A main liquid chamber having a thick vibration-proof rubber body as a chamber wall and a sub-liquid chamber having a thin rubber film as a chamber wall are partitioned by a partition plate, and these liquid chambers are squeezed and flow passaged. In the liquid-filled vibration isolator that is communicated with each other, a foam having a large number of air bubbles that are independent of each other and having an internal pressure absorbing action in the main liquid chamber is provided in the main liquid chamber, and the foaming ratio of the foam is A liquid-filled anti-vibration device characterized by partially changing 3. The liquid-filled anti-vibration device according to claim 1, wherein a stopper that restricts the movement of the foam is provided in the main liquid chamber.