JPH0543886B2 - - Google Patents

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 of an automobile to absorb vibrations from the automobile engine and prevent the vibrations 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 structure 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 (for example,
107142).

However, in this vibration isolator, when the input vibration is a high frequency of 50 Hz or higher, for example, the amplitude is small and the restriction passage becomes clogged, the internal pressure rises and the spring constant becomes high. As a result, the transmission rate of vibration increases, causing the car to become uncomfortable to ride. For this reason, vibration isolators that can absorb high frequency vibrations have been proposed. (See Japanese Unexamined Patent Publication No. 57-9340 as an example).

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

[Purpose of the Invention] In consideration of the above facts, the present invention aims to provide a vibration isolator that not only absorbs vibrations in a high frequency range, but also damps vibrations over a wide range in a low frequency range. be.

[Summary of the Invention] 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,
Restriction passages of different dimensions are provided in the plurality of partition members to communicate adjacent small liquid chambers, and vibrations are attenuated over a wide range in a low frequency range by such a plurality of restriction passages, In addition, at least one of the partition members is provided with a displacement means in a position different from the restriction passage provided in the partition member and in parallel with the restriction passage, so that the volume between adjacent small liquid chambers can be selectively changed. This provides 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 portion of the bottom plate 10 for attachment to a vehicle body (not shown).

The outer circumferential portion of a connecting plate 14 is fixed to the outer circumferential portion of the bottom plate 10, and the central portion of the connecting plate 14 is raised into a cylindrical shape, and a through hole 15 is formed in the central portion.

A peripheral portion of a lower diaphragm 16 formed of an elastic body is held between the connecting plate 14 and the bottom plate 10. The center part of the bottom plate 10 and the lower diaphragm 1
6 constitutes an air chamber 18, and the lower diaphragm 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 the rubber 20.

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. Top plate 24
is the mounting surface of the engine (not shown), and bolt 2
6, the engine is fixed to the top plate 24.

An upper diaphragm 28 and a partition plate 30 as a partition material are attached to the connection portion between the top plate 24 and the connection plate 22, and 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. That is, the upper diaphragm 28 and the partition plate 3
0 and an upper liquid chamber 32 and a partition plate 30
A middle liquid chamber 34 is formed between the rubber 20 and the rubber extension 20A, and a lower liquid chamber 36 is formed between the rubber extension 20A and the lower diaphragm 16. The lower liquid chamber 36 and the middle liquid chamber 34 are through holes formed in the rubber extension 20A, and are communicated only through an orifice 38.

The partition plate 30 has a circular plate 4 as shown in FIG.
0 is fixed. A substantially C-shaped raised portion 42 is formed near the outer periphery of the disc 40, and an elongated orifice 44 is formed between the disc 40 and the partition plate 30. This orifice 44 is inserted into the upper liquid chamber 32 and the middle liquid chamber 3 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.
It is connected to 4.

A through hole 50 is bored in the center of the partition plate 30 and the disk 40, and a movable body 52 is attached thereto. In other words, the orifice 44 is placed on the partition plate 30.
A movable body 52 is attached to the partition plate 30 so as to be parallel to the orifice 44 and at a position different from the raised portion 42 forming the movable body 52 . This movable body 52
is a synthetic resin disk having an H-shaped cross section, and the peripheral edge of the through hole 50 enters into the outer circumferential groove 54. The width of the outer circumferential groove 54 is slightly larger than the total thickness of the partition plate 30 and the disk 40, thereby allowing the movable body 52 to move in the axial direction. 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 amount of movement of the movable body 52, it is possible to suppress an increase in the dynamic spring constant at the target amplitude position.

Next, the operation of this embodiment will be explained. The installation is completed by fixing the bottom plate 10 to the body of the automobile via bolts 12, and mounting and fixing the automobile engine to the top plate 24 with bolts 26. When the engine is installed, the weight of the engine acts on the bolt 26, so that the pressure in the middle liquid chamber 34 increases. This pressure is applied to the upper liquid chamber 3 through the orifice 38 and the orifice 44.
2 and the lower liquid chamber 36, and the air chamber 18 and the air chamber 31 are reduced in size.

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

When the vibration frequency is low, the amplitude is large, and the liquid in the middle liquid chamber 34, where the pressure rise phenomenon is repeated due to the vertical movement of the partition plate 30, flows through the orifices 38, 4.
4 into and out of the upper liquid chamber 32 and lower liquid chamber 36.
In this case, the damping effect based on the viscous resistance of the fluid flow generated in the orifices 38 and 44 improves the vibration damping effect.

In particular, orifice 38 and orifice 44 have different dimensions, so they can damp vibrations at different frequencies, and have loss coefficients as shown by the solid line in FIG. Decrease spring constant. On the other hand, the third
In the conventional example shown by the broken line in Fig. 4, the loss coefficient peaks at only one place, so the dynamic spring constant shown in Fig. 4 has no part to be reduced in the low frequency region, and engine vibration is easily transmitted to.

In this case, in this embodiment, by changing the shapes and dimensions of the orifice 38 and the orifice 44, the third
The peak frequency of the loss coefficient shown in the figure can be adjusted arbitrarily.

Also, if the engine vibration has a high frequency of, for example, 50Hz or higher, the amplitude is small and the orifice 3
8 and 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. is attenuated. By changing the size and shape of this movable body 52, desired absorption characteristics can be obtained.

In particular, as shown in FIG. 1, the movable body 52 is 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 3.
0, it is possible to increase its outer diameter, thereby increasing 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 upside down. Therefore, the upper liquid chamber 32 and the middle liquid chamber 34 are partitioned by a raised part of the connecting plate 14, and a cylindrical body 56 fixed to this raised part forms an orifice 38. Also, a partition plate 30 partitions the middle liquid chamber 34 and the lower liquid chamber 36.
As in the previous embodiment, a movable body 52 is provided to enable minute vibrations during high frequency vibration. Further, the partition plate 30 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 formed by connecting the flat plate portion of this partition plate 30 and the cylindrical portion 30A.
A C-shaped orifice 44 is fixedly fixed between the 0A and the 0A and has a planar shape similar to that of the previous embodiment.

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

Therefore, in this embodiment as well, it is possible to obtain the same effects as in the previous embodiment.

Next, FIG. 6 shows a third embodiment of the present invention. This embodiment has substantially the same shape as the first embodiment, but differs in the orifice attached to the partition plate 30 that partitions the upper liquid chamber 32 and the middle liquid chamber 34 and in the high-frequency vibration absorbing means.

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

Further, a raised portion 60 is formed in the center of the partition plate 30, and a small chamber 64 is formed between the raised portion 60 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 vibration, 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 vibration, the movable plate 62
The upper liquid chamber 32 and the middle liquid chamber 34 are configured to selectively change their volumes to absorb vibrations.

[Effect 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, and each of these partition members is provided with a restriction passage of a different size, so that vibrations can be absorbed over a wide range in the low frequency region. It has excellent effects. Further, at least one of the plurality of partition members is provided with a displacement means at a position different from the restriction passage provided in the partition member and in parallel with the restriction passage to select the volume between adjacent small liquid chambers. Since it is possible to change the frequency, it has an excellent effect of being able to absorb vibrations even in a high frequency range.

[Brief explanation of the drawing]

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 related parts thereof, and FIG.
FIG. 4 is a diagram showing the loss coefficient versus vibration frequency in the embodiment. FIG. 4 is a diagram showing the dynamic spring constant versus vibration frequency in the first embodiment. FIGS. FIG. 16...Lower diaphragm, 20...Rubber, 28
... Upper diaphragm, 30 ... Partition plate, 32 ...
Upper liquid chamber, 34...Middle liquid chamber, 36...Lower liquid chamber, 38
...Orifice, 44...Orifice, 52...
Movable body, 62...movable plate.

Claims (1)

[Scope of Claims] 1. A hollow chamber which is interposed between the vibration generating part and the vibration receiving part and mainly consists of a hollow molded body made of an elastic material and which mainly absorbs vibrations is used as a liquid chamber, and this liquid chamber is divided into a plurality of partition members. partitioned into at least three small liquid chambers, each of the plurality of partition members is provided with a restriction passage of a different size to communicate adjacent small liquid chambers, and at least one of these partition members is provided with a restriction passage having a different size. A vibration isolating device characterized in that a displacement means is provided at a position different from the provided restriction passage and in parallel with the restriction passage to selectively change the volume between adjacent small liquid chambers. 2. The vibration isolator according to claim 1, wherein the displacement means is a movable body provided in a hole penetrating the partition member so as to be relatively movable by a certain amount. 3. The vibration isolating device 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.