JP3155968B2 - Anti-vibration device - 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 type vibration damping device used in automobiles, general industrial machines and the like, which absorbs and attenuates vibration from a vibration generating portion.

[0002]

2. Description of the Related Art In a motor vehicle, a vibration isolator as an engine mount is provided between an engine and a vehicle body to prevent transmission of engine vibration to the vehicle body. In such an engine mount, it is required that the dynamic spring constant during high-frequency vibration be reduced. There has been proposed a liquid-filled type vibration damping device in which the liquid resonates near the fins to lower the dynamic spring constant.

[0003] As a liquid filled type vibration damping device that resonates a liquid in a restricted passage, a vibration damping device as shown in FIG. 7 is known. As shown in FIG. 7 , the outer cylinder 102 of the vibration isolator 100 is attached to one side of the mounting member 10 with an elastic body 104 interposed therebetween.
6 is attached, and the other end is attached with a diaphragm 108 and a lower attachment plate 109. The inside of the outer cylinder 102 is partitioned by the partition plate 110 into the pressure receiving liquid chamber 112 and the sub liquid chamber 11.
4 and is divided into a pressure receiving liquid chamber 112 and a sub liquid chamber 114.
Are connected to each other by a restriction passage 116 provided in the partition plate 110. A liquid 118 is filled in the pressure receiving liquid chamber 112, the sub liquid chamber 114, and the restriction passage 116 without any gap.

In this vibration isolator 100, a mounting member 106 is connected to an engine, and a lower mounting plate 109 is connected to a vehicle body. When the vibration of the engine is input to the vibration isolator 100, the elastic body 104 is deformed and the liquid 118 is transferred to the pressure receiving liquid chamber 1.
It moves between 12 and the auxiliary liquid chamber 114. Here, the liquid 118 resonates in the restriction passage 116, the dynamic spring constant of the vibration isolator 100 is reduced, and the vibration is effectively absorbed.

[0005] As a liquid-filled type vibration damping device having fins provided in the liquid chamber, a vibration damping device 20 as shown in FIG.
0 is known. As shown in FIG.
A mounting member 208 is mounted on one side of the outer cylinder 206 via an elastic body 210, and a diaphragm 212 and a lower mounting plate 214 are mounted on the other side. The inside of the outer cylinder 206 is a liquid chamber 216, and the liquid 2
18 are filled without gaps. Fins 220 connected to the mounting member 208 are provided in the liquid chamber 216.

When the vibration of the engine is input to the vibration isolator 200, the liquid 218 near the outer periphery of the fin 220 resonates, the dynamic spring constant of the vibration isolator 200 is reduced, and the vibration is effectively absorbed.

[0007]

However, in the vibration isolator 100 shown in FIG. 7 , the vibration frequency is 400 Hz, 50 Hz.
In a high frequency range such as 0 Hz, there is a problem that the dynamic spring constant of the vibration isolator cannot be reduced.

That is, the resonance frequency f of the liquid 118 in the restriction passage 116 of the vibration isolator 100 is represented by K (spring constant of the elastic body) as expressed by the following equation (1).
A (effective pressure receiving area of elastic body), a (pressure receiving area of restricted passage), h (length of restricted passage), ρ (density of liquid) and Mw
(Additional mass of liquid).

F∝ [K / ｛(A / a) ² ρah + Mw｝] ^1/2 (1) f: Resonance frequency of liquid K: Spring constant of elastic body A: Effective pressure receiving area of elastic body (See FIG. 7 ) a: Pressure receiving area of restriction passage (see FIG. 7 ) h: Length of restriction passage (see FIG. 7 ) ρ: density of liquid Mw; additional mass of liquid Here, the right side of the above equation (1) Term denominator ｛((A / a) ² ρ
ah + Mw)}, if A {a, then (A /
a) ² ρah occupies a weight greater than Mw and A =
As approaching a, Mw occupies a weight greater than (A / a) ² ρah. In order to effectively absorb high-frequency vibrations in the vibration isolator 100, the resonance frequency of the liquid in the restriction passage 116 must be increased. Increase (K) or
Alternatively, the denominator {((A / a) ² ρah + Mw)} needs to be reduced.

By the way, when K is increased, the vibration isolator 10
Since the value of the dynamic spring constant of 0 itself becomes high, there is a limit in increasing K. Further, in order to reduce A, it is necessary to reduce the size (diameter) of the vibration isolator 100, and there is a balance with the durability of the elastic body 210, which also has a limit.

It is also conceivable to increase a. However, when a is increased, A becomes closer to A = (A / a) ²
The ratio of Mw occupying the weight becomes larger than ρah, so that a certain frequency (actually, frequency 250H
The resonance frequency cannot be increased more than about z).

Further, in the vibration isolator 200 shown in FIG. 8 in which the fin 204 is provided in the liquid chamber 202, when the outer cylinder 206 and the mounting member 208 are relatively moved in the radial direction,
04 may interfere with the outer cylinder 206 and the elastic body 210.

In view of the above, an object of the present invention is to provide a vibration damping device capable of effectively absorbing even high-frequency vibrations.

[0014]

According to the vibration isolator of the present invention, a first mounting member is connected to one of the vibration generating section and the vibration receiving section, and is connected to the other of the vibration generating section and the vibration receiving section. Second
A mounting member, an elastic body provided between the first mounting member and the second mounting member and deforming when vibration occurs, a hollow chamber which can expand and contract the elastic body as a part of a partition wall, A restricting passage forming member that divides the hollow chamber into an air chamber and a liquid chamber, and that forms a restricting passage between the air chamber and the liquid chamber, the cross-sectional area of which is narrowed with respect to the air chamber and the liquid chamber; And a liquid which is injected into the hollow chamber and has a liquid level set in the middle of the restriction passage.

[0015]

According to the vibration isolator of the present invention, when the first mounting member is connected to a vibration source such as an engine and the second mounting member is connected to a vibration receiving portion such as a vehicle body, the vibration is reduced to the first. The support member is supported by the vibration receiving portion via the mounting member, the elastic body, and the second mounting member. At this time, the vibration is absorbed not only by the resistance based on the internal friction of the elastic body but also by the resonance of the liquid in the restricted passage whose cross-sectional area is narrowed with respect to the air chamber and the liquid chamber.

Here, the resonance frequency f at which the liquid resonates in the restricted passage is f {[K / {(A / a) ² ρah + Mw}].
^1/2 (where K (spring constant of elastic body), A (effective pressure receiving area of elastic body), a (pressure receiving area of restricted passage), h (length of restricted passage), ρ (density of liquid) , Mw (added mass of liquid)), and according to the vibration damping device of the present invention, the liquid surface of the liquid is set in the middle of the restricted passage, so that the added mass (Mw) of the liquid is smaller than the conventional mass. Smaller than the vibration device. Therefore, in the equation representing the resonance frequency f of the liquid in the restricted passage, the value of the denominator in the right term can be reduced. For this reason, the vibration damping device of the present invention can make the resonance frequency f of the liquid in the restriction passage higher than that of the conventional vibration damping device, and can reduce the dynamic spring constant to a higher frequency range than the conventional vibration damping device. . Accordingly, the vibration damping device of the present invention can effectively absorb even higher frequency vibrations than before.

[0017]

Embodiment 1 First Embodiment FIGS. 1 and 2 show a first embodiment of a vibration isolator 10 according to the present invention.
It is explained according to.

As shown in FIG. 1, the vibration isolator 10 is provided with a lower mounting base 12 as a first mounting member. The lower mounting base 12 has a substantially columnar shape, and a mounting bolt 14 protrudes from the lower center thereof, and is fixed to a vehicle body (not shown) as an example.

An inner periphery of a ring-shaped elastic body 14 is vulcanized and bonded to an outer periphery of the lower mounting base 12, and an outer periphery of the elastic body 14 is formed as a cylindrical second mounting member. The lower end of the outer cylinder 16 is vulcanized and bonded to the inner periphery.

An upper mounting plate 18 is provided above the outer cylinder 16. The peripheral edge of the upper mounting plate 18 is
6 is fixed by caulking to the upper end. The center of the upper mounting plate 18 is projected outward in the axial direction, and a mounting bolt 20 for fixing an automobile engine (not shown) is provided in the center.
Are erected toward the outside in the axial direction.

Here, the partition member 2 is housed in the hollow chamber 22 surrounded by the outer cylinder 16, the elastic body 14, and the upper mounting plate 18.
6 are arranged. The partition member 26 is formed in a substantially cylindrical shape with a synthetic resin or the like, and the outer periphery is in close contact with the inner periphery of the outer cylinder 16. The upper end of the partition member 26 has a flange 2
6C is provided, and this flange portion 26C is
6 and the upper mounting plate 18 to be clamped and fixed.

A large diameter recess 28 is formed on the upper mounting plate 18 side of the partition member 26, which is a restriction passage constituting member, and a circular restriction passage 30 penetrating in the axial direction is formed in the shaft core. ing.

A liquid chamber 32 is provided between the partition member 26 and the elastic body 14, and an air chamber 34 is provided between the large-diameter recess 28 and the upper mounting plate 18. A liquid 24 such as ethylene glycol is injected into the liquid chamber 32, and the amount of the liquid 24 is adjusted such that the liquid surface 24A of the liquid 24 is positioned at the axial center of the restriction passage 30 when the engine is mounted (when used). Is set.

Next, the operation of this embodiment will be described. The vibration isolator 10 has a shaft center substantially parallel to the vertical direction, the lower mounting base 12 is fixed to a vehicle body (not shown), and an engine (not shown) is mounted and fixed to the support base 24.

Here, the vibration of the engine is caused by the vibration isolator 1
0, the elastic body 14 is deformed and the lower mounting base 12 is deformed.
And the upper mounting plate 18 are relatively displaced. The liquid 24 moves up and down in the restriction passage 30 and resonates in the restriction passage 30 to lower the dynamic spring constant of the vibration isolator 10. Thereby, the vibration of the engine is effectively absorbed.

Further, in the vibration isolator 10, the liquid 24
Of the liquid 24 is set such that the liquid surface 24A is located at the axial center of the restriction passage 30, so that the liquid chamber and the restriction passage are all filled with liquid as compared with the conventional vibration isolator. Therefore, the added mass of the liquid 24 is small. Therefore, the expression f 式 [K / ｛(A / a) ² ρah +
Mw｝] ^1/2 (where K (spring constant of elastic body), A
(Effective pressure receiving area of elastic body), a (pressure receiving area of restriction passage), h (length of restriction passage), ρ (density of liquid), Mw
(Additional mass of liquid)), the value of the denominator in the right term becomes smaller, so that the vibration damping device 10 has a resonance frequency of liquid higher than that of the conventional vibration damping device in which the liquid chamber and the restricted passage are all filled with liquid. Is high (in this embodiment, the resonance frequency is 400 to 500).
(Near Hz), and the dynamic spring constant is reduced to a high frequency range. Therefore, the vibration isolator 10 can effectively absorb even higher frequency vibrations than the conventional vibration isolator (see FIG. 2).

The anti-vibration device 10 includes a restriction passage 30
By changing the position of the liquid surface 24A within the chamber, that is, by changing the amount of the liquid 24 to be injected (changing the added mass of the liquid 24), the resonance frequency f can be easily tuned within a predetermined range. You can do it too. Further, since the change of the resonance frequency f does not involve a change of the structure, the number of parts does not increase and the structure does not become complicated.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS.

The vibration damping device 10 of this embodiment shows an example in which the present invention is applied to a cylindrical engine mount.

As shown in FIG. 3, in the vibration damping device 10, an inner cylinder 42 as a first mounting member is coaxially disposed within an outer cylinder 40 as a cylindrical second mounting member. I have. In this embodiment, the inner cylinder 42 is connected to an engine (not shown) as a vibration generator, and the outer cylinder 40 is connected to a vehicle body (not shown) as a vibration receiver.

An intermediate cylinder 44 is coaxially arranged in the outer cylinder 40, and the outer periphery of the intermediate cylinder 44 is in close contact with the inner periphery of the outer cylinder 40. Note that both ends of the outer cylinder 40 are caulked inward in the radial direction so that the intermediate cylinder 44 does not fall out of the outer cylinder 40. Further, grooves 46 are formed in the vicinity of both ends in the axial direction on the outer periphery of the intermediate cylinder 44 in the direction around the axis. O-rings 48 are accommodated in these grooves 46, and the sealing performance between the outer cylinder 40 and the intermediate cylinder 44 is enhanced.

An elastic body 50 is disposed between the inner cylinder 42 and the intermediate cylinder 44.
2 is vulcanized and bonded to the outer circumference, and the outer circumference is vulcanized and bonded to the inner circumference of the intermediate cylinder 44. A groove 52 having a rectangular cross section is formed around the axis at the axial center of the outer periphery of the elastic body 50. The liquid 2 is contained in the hollow chamber 54 surrounded by the groove 52 and the outer cylinder 40.
4 is injected in a predetermined amount.

In the groove 52 of the elastic body 50, there are provided projections 56 projecting toward the outer cylinder 40 on both sides in the horizontal direction with the inner cylinder 42 interposed therebetween, and the lower side than the projection 56 of the hollow chamber 54 is provided. A liquid chamber 57 is provided, and an air chamber 59 is provided above the protrusion 56. A space between the projection 56 and the outer cylinder 40 is a restriction passage 58. Note that the position of the liquid surface 240 of the liquid 24 substantially coincides with a horizontal plane passing through the axis in use.

Here, the vibration of the engine is caused by the vibration isolator 1
When input to 0, the elastic body 50 is deformed and the inner cylinder 42 and the outer cylinder 40 are relatively displaced. The liquid 24 moves up and down in the restriction passage 58, resonates in the restriction passage 58, and the dynamic spring constant of the vibration isolator 10 decreases. Thereby, the vibration of the engine is effectively absorbed.

The vibration isolator 10 of this embodiment, like the vibration isolator 10 of the first embodiment, has a small additional mass of the liquid 24, and is therefore smaller than the conventional vibration isolator in which the inside of the restricted passage is completely filled with the liquid. Even high frequency vibrations can be absorbed.

Also, the vibration isolator 10 of the present embodiment is similar to the vibration isolator 10 of the first embodiment.
By changing the position of 4A, tuning of the resonance frequency f can be easily performed within a predetermined range.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG .

This embodiment shows an example in which the present invention is applied to a strut mount of an automobile.

As shown in FIG . 5 , in this vibration isolator 10, an outer cylinder 82 as a second mounting member is disposed inside a mounting frame 80 connected to a vehicle body (not shown) . An inner cylinder 84 as a first mounting member is coaxially disposed. A bearing 86 connected to a rod (not shown) of the shock absorber is caulked and fixed inside the inner cylinder 84.

The outer cylinder 82 is provided coaxially with the intermediate cylinder 8.
8 is provided, and the outer circumference of the intermediate cylinder 60 is
It is in close contact with the inner circumference.

An elastic body 90 is provided between the inner cylinder 84 and the intermediate cylinder 88, and an elastic body 90 is provided around the outer periphery of the inner cylinder 84.
Are bonded together, and an elastic body 90
Is vulcanized and adhered. A concave portion 92 is formed on the outer periphery of the elastic body 90 at the center in the axial direction around the axis. A predetermined amount of the liquid 24 is injected into a hollow chamber 94 surrounded by the concave portion 92 and the outer cylinder 82.

The elastic body 90 is provided with a protrusion 96 protruding toward the outer cylinder 40 at the center in the axial direction of the concave portion 92 as a restriction passage constituting member. An annular reinforcing plate 98 is embedded.

In this embodiment, the projection 96 of the hollow chamber 94 is provided.
The lower side is a liquid chamber 95, the upper side of the protrusion 96 is an air chamber 97, and the space between the protrusion 96 and the outer cylinder 82 is a restriction passage 99. The liquid surface 24A of the liquid 24
Is located at the axial center of this restriction passage 99.

Here, when vibration is input to the vibration isolator 10, the elastic body 90 is deformed, the inner cylinder 84 and the outer cylinder 82 are relatively displaced, and the liquid 24 moves back and forth in the restricted passage 99. The liquid 24 moves up and down in the restriction passage 99, resonates in the restriction passage 99, and the dynamic spring constant of the vibration isolator 10 decreases. Thereby, the vibration of the rod (not shown) of the shock absorber is effectively absorbed.

The vibration damping device 10 of this embodiment, like the vibration damping device 10 of the first embodiment, has a small additional mass of the liquid 24, and is therefore smaller than the conventional vibration damping device in which the inside of the restricted passage is completely filled with the liquid. Even high frequency vibrations can be absorbed.

Also, the vibration isolator 10 of the embodiment is similar to the vibration isolator 10 of the first embodiment.
By changing the position A (the amount of the liquid 24 injected into the hollow chamber 94), the tuning of the resonance frequency f can be easily performed within a predetermined range.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG .

[0059] This embodiment is a modification of the third embodiment are denoted by the same reference numerals for the same structure as the third embodiment,
The description is omitted.

In this embodiment, no projection 96 is provided in the concave portion 92 of the elastic body 90, and a restriction passage constituting member 93 is provided in the hollow chamber 94. The restriction passage forming member 93 is formed in a ring shape, and its outer periphery is in close contact with the inner periphery of the outer cylinder 82. A thick annular plate 93A protruding toward the concave portion 92 is provided on the inner periphery of the restriction passage constituting member 93, and a restriction passage 99 is formed between the annular plate 93A and the concave portion 92 of the elastic body 90. I have. The other configurations and operations are the same as in the third embodiment.

[0061]

As described above, the anti-vibration device of the present invention has the above-mentioned structure, and therefore has an excellent effect of effectively absorbing even high-frequency vibrations.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along an axis of a vibration isolator according to a first embodiment of the present invention.

FIG. 2 is a graph showing a vibration isolation characteristic (a relationship between a vibration frequency and a dynamic spring constant) of the vibration isolation device according to the first embodiment of the present invention.

FIG. 3 shows a vibration isolator according to a second embodiment of the present invention.
FIG. 3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a sectional view perpendicular to an axis of a vibration isolator according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a vibration isolator according to a third embodiment of the present invention;
FIG.

FIG. 6 is a schematic view of an anti-vibration device according to a fourth embodiment of the present invention;
FIG.

FIG. 7 is a sectional view taken along an axis showing a conventional vibration damping device.
is there.

FIG. 8 is a sectional view taken along an axis showing a conventional vibration damping device.
is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibration isolator 12 Lower mount (1st mounting member) 14 Elastic body 16 Outer cylinder (2nd mounting member) 22 Hollow chamber 24 Liquid 24A Liquid surface 30 Restriction passage 40 Outer cylinder (2nd mounting member) 42 Inner cylinder (first attachment member) 50 Elastic body 54 Hollow chamber 58 Restricted passage 82 Outer cylinder (second attachment member) 84 Inner cylinder (first attachment member) 90 Elastic body 94 Hollow chamber 99 Restricted passage

Continuation of the front page (56) References JP-A-58-81240 (JP, A) JP-A-3-30634 (JP, U) JP-A-55-168742 (JP, U) JP-A-57-142 (JP) , U) Japanese Utility Model Application 59-147934 (JP, U) French Patent Application Publication 2117240 (FR, A1) West German Patent Application Publication 2921866 (DE, A1) (58) Fields investigated (Int. Cl. ⁷ , (DB name) F16F 13/08 F16F 13/20

Claims (1)

(57) [Claims] A first mounting member connected to one of the vibration generating unit and the vibration receiving unit; a second mounting member connected to the other of the vibration generating unit and the vibration receiving unit; and the first mounting An elastic body that is provided between the member and the second mounting member and that is deformed when vibration is generated; a hollow chamber that can expand and contract using the elastic body as a part of a partition; and the hollow chamber is formed into an air chamber and a liquid chamber. A restricting passage forming member that defines a restricting passage having a narrowed sectional area with respect to the air chamber and the liquid chamber between the air chamber and the liquid chamber, and a liquid surface injected into the hollow chamber. And a liquid set in the middle of the restriction passage.