JPS62261730A - Vibration damping device - Google Patents

Abstract

PURPOSE:To reduce an absolute spring modulus of a vibration damping device down to a frequency range higher than a resonance frequency of multiple small liquid chambers formed in an elastic body connecting an outer and an inner tubes together by attaching a weight via an elastic body to the outer tube. CONSTITUTION:An intermediate tube 16 is provided with a window 22. An elastic body 20 adjacent to the window 22 is formed with a recess 24 to form small liquid chambers 26 and 28 filled with water, oil, etc., with both of the chambers 26 and 28 communicating with each other via grooves 30. An elastic body 32 with part of it connected to the elastic body 20 projects into the small liquid chamber 26. A weight 34 of a weight which causes resonance at a specified frequency is embedded in the projecting part of the elastic body 32. If the cross-sectional area of an orifice 30 and the weight of the weight 34 are adjusted so that the resonance point of the weight 34 agrees with the part with which an absolute spring modulus becomes the lower limit due to resonance of liquid, an absolute spring modules which is low down to a high frequency range can be obtained by means of average characteristics of both of the components.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration isolating device that is applied to engine mounts, differential mounts, bushings used in parts to which vibrations are transmitted, etc. of vehicles.

[Background technology]

Fluid-filled vibration isolators are used as vehicle engine mounts and the like.

This vibration isolator has a configuration in which the inner and outer cylinders are connected by an elastic body, and a plurality of small liquid chambers are formed within the elastic body, and these are communicated through a restriction passage. For this reason, when the liquid in one small liquid chamber moves to the other small liquid chamber during vibration, resonance of the liquid occurs in the restricted passage section through which the liquid passes, and the vibration is absorbed.

However, such a vibration isolator has the disadvantage that the absolute spring constant rapidly increases at a frequency slightly higher than the frequency at which resonance occurs, resulting in poor sound transmission characteristics at high frequencies.

The present invention has been made in consideration of the above-mentioned facts, and an object of the present invention is to obtain a vibration isolating device that can suppress an increase in the absolute spring constant after the liquid resonates.

[Summary and operation of the invention]

The present invention is a vibration isolating device in which an elastic body connects an inner and outer cylinder, and a plurality of small liquid chambers are formed in the elastic body, and these are communicated through a restriction passage. It is characterized by a weight attached to it.

Therefore, in the present invention, vibrations can be absorbed by using the resonance of the weight at frequencies higher than the frequency at which the liquid resonates. By tuning the cross-sectional area of the orifice and the weight of the weight so that the resonance of the weight and the resonance of the liquid overlap, it is possible to obtain an average characteristic of both, and a low absolute spring constant up to a high frequency range.

[Embodiments of the invention]

As shown in Fig. 1.2, a vibration isolator 10 according to this embodiment
In this case, an inner cylinder 12 and an outer cylinder 14 are arranged coaxially. The inner cylinder 12 is connected to a suspension device of an automobile (not shown), and the outer cylinder 14 is connected to the body of an automobile (not shown).

An intermediate cylinder 16 is press-fitted into the inner circumference of the outer cylinder 14. An O-ring 18 is attached to the outer periphery of the intermediate cylinder 16 to create an airtight state between the intermediate cylinder 16 and the outer cylinder 14.

An elastic body 20 such as rubber is vulcanized and bonded between the inner peripheral portion of the intermediate cylinder 16 and the inner cylinder 12 to connect the inner cylinder 12 and the outer cylinder 14.

A window 22 is bored in the intermediate cylinder 16 from the opposite direction across the axis, and a recess 24 is formed in the elastic body 20 continuously from the window 22. These recesses 24 are filled with a liquid such as water or oil to constitute small liquid chambers 26,28. These small liquid chambers 26 and 28 communicate with each other via a groove 30 formed on the outer periphery of the intermediate cylinder 16.

An elastic body 32, which is partially connected to the elastic body 20, protrudes into the small liquid chamber 26, and a weight 34 is embedded in the protruding tip of the elastic body 32. This weight 34 has such a size and weight as to cause resonance at a predetermined frequency.

In this embodiment configured in this way, the elastic body 20 is vulcanized and bonded between the inner cylinder 12 and the intermediate cylinder 16, and the intermediate cylinder 16
is assembled by being press-fitted into the outer cylinder 14.

When the vibration acting on the inner cylinder 12 has a relatively low frequency, the elastic body 20 absorbs the vibration by internal friction.

Furthermore, when the vibration becomes a high frequency, the vibration is absorbed by the resistance and resonance when the liquid in the small liquid chamber 26 and the small liquid chamber 28 passes through the groove 30.

As shown in FIG. 4, the absolute spring constant of the liquid in the liquid chamber increases rapidly at a frequency slightly higher than the vibration frequency of this resonance.

However, in this embodiment, the weights 34 are attached via the elastic body 32, so if the weights of both weights 34 are tuned, the average characteristics of both weights 34 can be adjusted as shown by the solid line in FIG. Low absolute spring constants can be obtained up to high frequency ranges.

Next, FIG. 5 shows a second embodiment of the present invention.

In this embodiment, a vibration isolator having an elastic body between the inner and outer cylinders, a plurality of liquid chambers, and a communication passage connecting the liquid chambers is attached to a collar 50 at the end of the link 40. For example, the inner cylinder 12 is connected to the vehicle body. The opposite side of the link is fixed to the axle.

A stopper 42 protrudes from the inner cylinder 12, and the inner cylinder 12
The amount of relative movement between the outer cylinder 14 and the outer cylinder 14 is limited.

Further, on the outer periphery of the collar 50, an elastic body 3 similar to that of the previous embodiment is provided.
2 and a weight 34 are attached, so that it has the same effect as the previous embodiment.

〔Effect of the invention〕

As explained above, the present invention provides a vibration isolator in which the inner and outer cylinders are connected by an elastic body, a plurality of small liquid chambers are formed in the elastic body, and these are communicated through a restriction passage, and the vibration isolator is connected to the inner cylinder or the outer cylinder. Since the weight is attached via an elastic body, it has an excellent effect of being able to reduce the absolute spring constant to a frequency range higher than the resonance frequency of the small liquid chamber.

[Brief explanation of drawings]

FIG. 1 shows a second embodiment of the vibration isolating device according to the present invention.
Figure 1-1 line sectional view, Figure 2 is Figure 1 line ■-■ sectional view,
Fig. 3 is an exploded perspective view showing the vibration isolator before assembly, Fig. 4 is a diagram showing the relationship between frequency and absolute spring constant, and Fig. 5 is a longitudinal sectional view showing the second embodiment of the present invention. It is. DESCRIPTION OF SYMBOLS 10... Vibration isolator, 12... Inner cylinder, 14... Outer cylinder, 16... Intermediate cylinder, 20... Elastic body, 26... Small liquid chamber, 28... Small liquid Chamber, 32... Elastic body, 34... Weight.

Claims (1)

[Claims] (1) A vibration isolator in which an elastic body connects the inner and outer cylinders, a plurality of small liquid chambers are formed in the elastic body, and these are communicated through a restriction passage, and the vibration isolator is connected to the inner cylinder or the outer cylinder through the elastic body. A vibration isolating device characterized by having a weight attached to it.