JPS60132144A - Vibration isolator - Google Patents

Abstract

PURPOSE:To enable to damp vibration over wide range in low frequency region by a structure wherein a liquid chamber lying between a vibration generating part and a vibration receiving part is partitioned into three small liquid chambers so as to pass liquid through restricted passages with different dimensions between adjacent small liquid chambers. CONSTITUTION:When vibration frequency is low, the vibration amplitude is large and the rising and falling phenomena of the pressure of the liquid in a middle liquid chamber 34 are repeated by the vertical movement of a partition plate 30, resulting in flowing the liquid in the middle liquid chamber 34 to/from an upper liquid chamber 32 from/to a lower liquid chamber 36 through orifices 38 and 44. The vibration prevention effect is improved by the damping action due to the viscous resistance of liquid flow produced at the orifices 38 and 44. On the other hand, when vibration frequency is high, the vibration amplitude is small and consequently the orifices 38 and 44 are put into clogged states. However, the minute axial vibration of a movable body 52 occurs and causes to alternately increase and decrease the volumes of the upper liquid chamber 32 and of the middle liquid chamber 34 so as to selectively change the volumes in order to dampen the high frequency vibration consequently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vibration isolator for reducing vibrations from a vibration source.

[Background Art] A vibration isolating device, generally called a vibration isolating rubber, is used, for example, in an engine mount I of an automobile to absorb vibrations from an automobile engine and prevent them from being transmitted to the vehicle body.

Two vibration-damping liquid chambers are provided as this vibration isolator, and the vibration from the vibration source is transmitted as a contraction force to one of the liquid chambers, and when the liquid in this liquid chamber is moved to the other liquid chamber through the restriction passage. A configuration has been proposed in which vibration is absorbed by a resistance force based on internal friction. In this type of vibration isolator, the longer the length of the restriction passage, the more effective it is, so measures have been taken to increase the length of the restriction passage.
10714'2).

However, in this vibration isolator, when the input vibration is a high frequency of, for example, 50 Hz or higher, the amplitude is small and the restriction passage becomes clogged, causing the internal pressure to become high and the spring constant to increase. As a result, the transmission rate of vibration is decreased, which causes the ride comfort of the vehicle to deteriorate. For this reason, vibration isolators that can absorb high frequency vibrations have been proposed. (
- For example, see Japanese Patent Application Laid-Open No. 57-9340).

However, in such a conventional vibration isolator, vibration damping is only possible at a fixed frequency in the low frequency vibration range, and damping over a wide range in the low frequency range is not possible.

[Objective 1 of the Invention] The present invention takes into account the following facts and aims to obtain a vibration isolating device capable of damping vibration over a wide range in a low frequency range.

[Summary of the Invention] In the vibration isolating device according to the present invention, a liquid chamber is divided into at least three small liquid chambers by a plurality of partition members, and each of the plurality of partition members is provided with a restriction passage of a different size so as to be adjacent to each other. The small liquid chambers are connected to each other, vibrations are damped over a wide range in the low frequency range by the plurality of restriction passages, and at least one of the partition members is provided with a displacement step so that the adjacent small liquid chambers are connected to each other. The volume between them can be selectively changed, thereby achieving vibration damping even in high frequency ranges.

[Embodiments of the Invention] FIG. 1 shows a sectional view of a vibration isolator to which the present invention is applied. This vibration isolator is used as an engine mount, and a bolt 12 is fixed to the center of the bottom plate 10 so that it can be attached to a vehicle body (not shown).

The vicinity of the outer periphery of a connection plate 14 is fixed to the outer periphery of the bottom plate io, and the vicinity of the center of the connection plate 14 is raised into a cylindrical shape, and a through hole 15 is formed in the center.

A peripheral edge of a lower tire flam 16 formed of an elastic body is sandwiched between the connection plate 14 and the bottom plate 1O. An air chamber 18 is located between the center of the bottom plate 10 and the lower diaphragm 16.
The lower guyaflame 16 is movable in the direction of expansion and contraction of the air chamber 18. This air chamber 18 may communicate with the outside through a suitable through hole provided in the bottom plate 10.

An extension portion 20A of a substantially cylindrical rubber 20 whose axis is perpendicular is vulcanized and bonded to the inner and outer peripheries of the raised portion of the connection plate 14. It is also possible to use other elastic materials in place of this rubber 2O.

The outer periphery of the rubber 20 is vulcanized and bonded to the inner periphery of a cylindrical connecting plate 22, and the upper end of this connecting plate 22 is caulked and fixed to the outer periphery of the top plate 24.

The center portion of this top plate 24 is raised, and a bolt 26 is fixed to the top surface of this raised portion. The top plate 24 is a mounting surface for an engine (not shown), and the engine is fixed to the top plate 24 by bolts 26.

An upper diaphragm 28 is provided at the connection between the top plate 24 and the connection plate 22.
and a partition plate 3O as a partition member is attached,
An air chamber 31 is formed between the upper diaphragm 28 and the top plate 24. The sealed space formed by the upper diaphragm 28, the rubber 20, and the lower diaphragm 16 is a liquid chamber filled with a liquid such as water, and this liquid chamber is divided into three parts. In other words, the old diaphragm 28 and the partition plate 3
0, an intermediate liquid chamber 3 formed between the partition plate 3O, the rubber 20, and the rubber extension 20A.
4. A lower liquid chamber 36 is provided between the rubber extension portion 20A and the lower tire flamm 16. This lower liquid chamber 3
6 and the medium liquid chamber 34 are communicated only through an orifice 38, which is a through hole formed in the rubber extension 20A.

A disk 40 is fixed to the partition plate 30 as shown in FIG. A substantially C-shaped raised portion 42 is formed near the outer periphery of the date plate 40, and an elongated orifice 44 is formed between the date plate 40 and the partition plate 3O. This orifice 44
is communicated with the upper liquid chamber 32 and the middle liquid chamber 34 through a through hole 46 formed in a part of the raised portion 42 and a through hole 48 formed in the partition plate 30 .

A through hole 50 is bored in the center of the partition plate 30 and the disc 40, and a movable body 52 is mounted therein. The movable body 52 is a synthetic resin disk having an H-shaped cross section, and the peripheral edge of the through hole 5O enters into the outer circumferential groove 54 of the movable body 52. The width dimension of this outer circumferential groove 54 is slightly larger than the total thickness of the partition plate 30 and the disc 40, so that the movable body 52 cannot be moved in the radial direction but can be moved in the axial direction. It becomes. It is preferable that the material of this movable body 52 has a specific gravity approximately equal to that of the liquid filled into the liquid chamber so that it can easily vibrate.

The movable body 52 may have a split structure in consideration of the convenience when installing it into the through hole 50, or the cross section may be T-shaped, and one side may be deformed after being inserted into the through hole 50. It is also possible to have an H-shaped cross section.

By adjusting the movement behavior of the 1f moving body 52, it becomes possible to suppress the increase in the dynamic spring constant at the target amplitude position.

Next, the operation of this embodiment will be explained. Bottom plate 10 is Porto 12
It is fixed to the car body through the port 2 to the top plate 24.
The installation is completed by mounting and fixing the automobile engine in step 6. When the engine is installed, the weight of the engine acts on the port 26, causing the pressure in the intermediate liquid chamber 34 to rise.

This pressure is applied to the orifice 38. It is transmitted to the upper liquid chamber 32 and the lower liquid chamber 36 via the orifice 44, and the air chamber 18 and the air chamber 29 are reduced in size.

When the engine is running, the vibrations generated by the engine are transmitted to the top plate 24.
transmitted via. The rubber 20 acts as a main vibration absorber, and can absorb vibrations by a damping function based on the internal friction of the rubber 20.

When the frequency of vibration is low, the amplitude is large and the partition plate 30
The liquid in the middle liquid chamber 34, where the upper pressure phenomenon A is repeated due to the vertical movement of , is discharged to the -L liquid chamber 32 and the lower liquid chamber 36 through the orifice 38.44.

In this case, the damping effect based on the viscous resistance of the fluid flow generated in the orifice 38, 44 improves the vibration damping effect.

In particular, orifice 38 and orifice 44 have different dimensions so that they can damp vibrations at different frequencies and have a loss factor as shown by the solid line in FIG. Decrease spring constant.

On the other hand, in the conventional example shown by the broken line in Fig. 3.4, the dynamic spring constant shown in Fig. 4 is reduced in the low frequency region because the loss coefficient is only at the peak point. Since there are no parts, engine vibrations are easily transmitted to the vehicle body.

In this case, in the tree embodiment, orifice 38 and orifice 4
By changing the shape and dimensions of 4, the peak frequency of the loss coefficient shown in FIG. 3 can be arbitrarily adjusted in one step.

Also, if the engine vibration has a high frequency, for example 50 Hz or higher, the amplitude is small, so the orifice 38.44
may become clogged. However, in this case, the volumes of the upper liquid chamber 32 and the middle liquid chamber 34 are selectively changed by alternately increasing and decreasing the volumes of the upper liquid chamber 32 and the middle liquid chamber 34 by slightly vibrating the movable body 52 in the axial direction, thereby attenuating the high-frequency vibrations. be done.

By changing the size and shape of this movable body 52, desired absorption characteristics can be obtained.

In particular, the outer diameter of the movable body 52 can be increased by providing the movable body 52 on a partition member having a larger area among the raised parts of the partition plate 30 and the connecting plate 14 that act as partition members, that is, the partition plate 30, as shown in FIG. This makes it possible to raise the upper limit of the frequency at which vibration is not damped and the transmission force increases, making it possible to absorb vibrations up to higher frequencies.

Next, FIG. 5 shows a second embodiment of the present invention. This embodiment has a structure in which the vibration isolating device of the previous embodiment is almost inverted. Therefore, the L liquid chamber 32 and the middle liquid chamber 34
are separated by a raised portion of the connecting plate 14, and a cylindrical body 56 fixed to this raised portion forms an orifice 38. Further, the partition plate 30 that partitions the middle liquid chamber 34 and the lower liquid chamber 36 is provided with a movable body 52, similar to the embodiment described above, so as to be able to vibrate minutely during high frequency vibration. Further, the partition plate 3O in this embodiment has a shape having a cylindrical portion 30A whose outer peripheral portion is bent at right angles, and the disk 40 is firmly fixed between the flat plate portion and the cylindrical portion 3OA of the partition plate 30. A C-shaped orifice 44 has a planar shape similar to that of the previous embodiment.

In this embodiment as well, the movable body 52 is attached to the raised portion of the connecting plate 14 as a pair of partition members and to the partition plate 30 having a larger area among the partition plates 30.

Therefore, in this embodiment as well, it is possible to achieve fAI effects similar to those of the previous embodiment.

Next, FIG. 6 shows a third embodiment of the present invention. This embodiment has almost the same shape as the first embodiment, but
The orifice formed in the partition plate 30 that partitions the upper liquid chamber 32 and the middle liquid chamber 34 and the means for absorbing high frequency vibrations are different.

That is, the cylindrical body 58 penetrates a part of the partition plate 30,
The through hole of this cylindrical body 58 serves as an orifice 44 that communicates the liquid chamber 32 and the middle liquid chamber 34.

Further, a raised portion 6O is formed in the center of the partition plate 30, and a small chamber 64 is formed between it and an elastic movable plate 62 whose periphery is fixed to the partition plate 30.

This small chamber 64 can be expanded and contracted by elastic deformation of the movable plate 62, and is communicated with the upper liquid chamber 32 through a plurality of small holes 66 formed in the raised portion 60.

Therefore, in this embodiment as well, during low frequency vibrations, the orifices 38 and 44 produce peak values of loss coefficients at different frequencies, reducing the dynamic spring constant over a wide range, and during high frequency vibrations, the movable plate 62 and the upper liquid chamber 32 The volume of the medium liquid chamber 34 is selectively changed to absorb vibrations.

[Effects of the Invention] As explained above, in the vibration isolating device according to the present invention, the liquid chamber is divided into at least three small liquid chambers by a plurality of partition members,
Since these partition members are provided with restriction passages of different sizes, they have the advantageous effect of being able to absorb vibrations over a wide range in the low frequency region.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of a vibration isolator according to the present invention, FIG. 2 is an exploded perspective view showing a partition plate as a partition member and its related parts, and FIG. FIG. 4 is a diagram showing the loss coefficient versus vibration frequency, FIG. 4 is a diagram showing the dynamic spring constant versus vibration frequency in the first embodiment, and FIGS. 5 and 6 are cross-sectional views showing the 2.3 embodiment of the present invention, respectively. It is. 16・φ・Lower diaphragm, 201・Rubber, 28th・Upper tire phragm. 30...Serving J plate, 32...I liquid chamber, 34.War/middle liquid chamber, 36...Upper liquid chamber, 38.Φ.Orifice, 44...Orifice, 52.Fist 11 Rocho moving body, 62...Movable plate. Agent Patent Attorney Atsushi Nakajima Figure 1 Figure 2 Figure 2 Figure 3 Vibration frequency (Hz) - Figure 4 Vibration shoulder pumping (Hz) - Figure 5

Claims (4)

[Claims] (1) A hollow chamber mainly composed of 839 hollow bodies made of elastic material, which is interposed between the vibration generating part and the vibration receiving part, is used as a liquid chamber, and this liquid chamber is divided into at least three partitions by a plurality of partition members. The plurality of partition members are provided with restriction passages of different dimensions to communicate the adjacent small liquid chambers, and at least one of these partition members is provided with a displacement means to separate the adjacent small liquid chambers. Selectively change the volume between the liquid chambers vI [! r
A vibration isolating device characterized by a Jf function. (2) The displacement means is inserted into the hole penetrating the partition member.
The vibration isolating device according to claim 1, characterized in that the vibration isolating device is provided with a relative movement Ljf by A. If) the device is a moving body. (3) The vibration isolator according to claim 1, wherein the displacement means is an elastic body that is attached to a hole penetrating the partition member so as to close the hole. (4) The vibration isolator according to any one of claims 1 to 3, wherein the displacement means is attached to a partition member having a large surface area among the plurality of partition members.