JPS61286633A - Fluid seal type vibration suppressing body - Google Patents

Abstract

PURPOSE:To suppress the vibration in the frequency range corresponding to the number of vibration damping parts at a same time by one vibration suppressing body by installing a plurality of vibration damping parts having different vibration suppressing object frequency onto one vibration suppressing body. CONSTITUTION:A plurality of vibration damping parts 26 and 27 having different vibration suppressing object frequency are installed onto a fluid seal type vibration suppressing body 10. Said vibration damping parts 26 and 27 are constituted of a pair of fluid chambers 20, 21 and 22, 23 which can be elastically deformed and communicate each other through orifices 24 and 25. Therefore, the vibration attenuation in a plurality of vibration frequency ranges is permitted by one vibration suppressing body by previously tuning each vibration suppressing object frequency in a plurality of vibration damping parts to each vibration frequency.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a fluid-filled vibration isolator.

BACKGROUND OF THE INVENTION In recent years, fluid-filled vibration isolators have been widely used in automobiles to effectively absorb engine vibrations, road vibrations, and the like. For example, Nirasan Service Bulletin No. 486 (published by Nissan Motor Co., Ltd. on August 1, 1981) No. 1II-21
There is something like the one shown on the page. As shown in FIG. 8, this fluid-filled vibration isolator l is provided on one side rubber bushing 2 of the lower link of a four-link suspension.
A pair of fluid chambers 4.4a sandwich the inner cylinder 3 in the direction in which the arm extends.
is formed in the rubber body 5 of the bushing 2, and both fluid chambers 4.43 are communicated via an orifice 6. Vibration damping section 7 is It is configured. When the vibration from the drive device, tires, etc. input to the link is transmitted to the vibration damping section 7, the volume of one of the fluid chambers 4, 4a changes and the fluid passes through the orifice 6. It is designed to be attenuated by

By the way, in the past, it was thought that vibrations of a fluid-filled vibration isolator were damped by the resistance when the fluid passes through an orifice, but in recent years, the present applicant has
As filed in No. 53, it has become clear that the fluid mass in the orifice 6 is the mass, and that it is dominated by a resonance phenomenon in which the expansion elasticity of the wall of the fluid chamber 4.4a is the spring. It has been revealed that it functions as a damper. Therefore, even in the conventional fluid-filled vibration isolator l, the resonance frequency is determined by the expansion elasticity of the rubber body 5 and the fluid mass of the orifice 6 when the volume of the fluid chamber 4° 4a is changed (resonance frequency (determining factor), so that only vibrations in this resonant frequency range are effectively damped. In other words, the frequency to be damped is determined to be one specific frequency range.

Problems to be Solved by the Invention However, the vibrations transmitted through the rubber bush 1 to the vehicle body include differential noise in the high frequency range of the differential gear, harshness in the low frequency range due to road vibration, etc. With the enclosed vibration isolator l, it is impossible to attenuate vibrations in different frequency ranges at the same time. Therefore, if vibration damping relies only on the fluid-filled vibration isolator t, vibrations that cannot be attenuated will still be transmitted to the heavy body side, causing a rattling sound or noise inside the vehicle interior, which will significantly reduce the quietness of the vehicle interior. The problem was that no significant improvement could be expected.

Therefore, an object of the present invention is to provide a fluid-filled vibration isolator that can simultaneously damp vibrations in different frequency ranges with one vibration isolator.

Means for Solving the Problems In order to achieve the above object, the present invention has a vibration damping section constituted by a pair of elastically deformable fluid chambers communicating through an orifice, the vibration damping section A fluid-filled type in which the vibration damping target frequency to be damped in the arrangement direction of the l pair of fluid chambers is determined by resonance frequency determining factors such as the fluid mass in the nosert fixture and the expansion elasticity of the fluid chamber wall. The vibration isolator is constructed by providing a plurality of vibration damping sections each having a different damping target frequency on one vibration isolator.

In the fluid-filled vibration isolator of the present invention with the above-described configuration, the vibration damping target frequency range of each of the plurality of vibration damping sections is tuned in advance to each vibration frequency of interest. , each vibration damping section can damp vibrations of different frequencies, and one vibration isolator can damp vibrations in a plurality of vibration frequency ranges.

EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the drawings. In this embodiment, a fluid-filled vibration isolator will be described using a suspension link bushing as an example, as in the prior art.

That is, FIG. 1 shows a fluid-filled vibration isolator lO showing an embodiment of the present invention, and this fluid-filled vibration isolator lO is provided on a rubber bush 12 of a lower link 11 of a four-link suspension. There is. That is, as shown in FIG. 2, the four-link suspension 13 is connected to an accelerator case 14 that houses the differential gear and the drive shaft.
A pair of upper links 15 and 1 are provided on the upper and lower sides, respectively.
A pair of lower links 11 are rotatably attached, and the tips of the upper link [5 and lower link 11] are rotatably connected to the vehicle body side (not shown). Note that rubber bushings are attached to each end of the upper and lower links 15, 11, and each link is connected to the aforesaid accelerator case 14 and the vehicle body via the rubber bushings. As shown in FIG. 1, the rubber bushing 12 is connected to an inner cylinder 16. It consists of an outer cylinder 17 and a rubber body 18 loaded between the outer cylinders 16 and 17, and the outer cylinder 7 is fixed to the link body 19. In this way, the lower link [l] is constituted by the rubber bushes 12 attached to both ends of the link body 19, and vibrations transmitted from the accelerator case I4 side to the vehicle body side are absorbed by the rubber bushes 12 at both ends of the link body 19. It has become so. Therefore, the lower link 1
1 has the function of connecting the accelerator case 14 to the vehicle body, and also has a link body 19 and a pair of rubber bushes 12.
One vibration isolator is constructed by the above.

Here, in this embodiment, in the rubber body 18 of the rubber bush 12 provided at one end of the lower link 11, a pair of first first and second
．． A second fluid chamber 20.21 and a pair of third and fourth fluid chambers 22.23 are formed in the vertical direction. These first. The second fluid chamber 20.21 and the third fluid chamber 20.21. Fourth fluid chamber 22.23
Of these, the first fluid chamber 20 and the third fluid chamber 22 are located in the inner cylinder 1.
6 is formed closer to the link body 19 and the second fluid chamber 2
The first and fourth fluid chambers 23 are provided on the side facing away from the link body 19. And the above-mentioned 1. Third fluid chamber 2
The second. Fourth
The fluid chambers 21 and 23 are formed in arcuate long holes along the inner circumference of the outer cylinder 17.

In addition, each pair of the first. The second fluid chamber 20.21 and the third fluid chamber 20.21. The fourth fluid chambers 22 and 23 have a first fluid chamber and a second fluid chamber, respectively.
The first and second
An incompressible fluid such as water is sealed within the orifice 24, 25 and each of the fluid chambers 20, 21, 22, 23. Therefore, when the rubber body 18 is deformed by external force vibration and the internal volume of each fluid chamber 20, 21, 22, 23 is changed, the fluid in the fluid chamber passes through the orifice 24, 25. 1st. The second fluid chamber 20.degree. 21 and the first orifice 24 constitute a first vibration damping section 26, and a pair of third. The fourth fluid chamber 22, 23 and the second orifice 25 constitute a second vibration damping section 27. By the way, these first. Second vibration damping section 26.27
The unique resonance frequency of
The fluid mass in the orifice 24.25 and the fluid chamber 20.2
1.22.23 As mentioned above, it is determined by the resonance frequency determining factors such as the expansion elasticity of the wall, that is, the rubber body 18, but in this embodiment, the diameters of the first orifice 24 and the second orifice 25 are made different. According to 1st. The damping target frequencies of the second vibration damping sections 26 and 27 are different. That is, the fluid mass of the orifice is, in detail, the equivalent of the square of the effective pressure-receiving area (A) of the liquid chamber divided by the cross-sectional area (a) of the orifice, multiplied by the movable fluid mass (a) in the orifice. The relationship between the orifice diameter and the resonant frequency obtained as a movable fluid mass is such that as the orifice diameter increases, the resonant frequency increases as shown in FIG. 3. Therefore, the diameter of the first orifice 24 of the first vibration damping section 26 is made relatively small, and the resonance frequency of the first vibration damping section 26 is set low, for example, in the 71-Schnes wind wave frequency range (30 ~150Hz), and the diameter of the second orifice 25 of the second vibration damping section 27 is made relatively large, so that the second vibration damping section 27
Set the resonant frequency of the
It is set to .

With the above-described structure, in the fluid-filled vibration isolator lO of this embodiment, vibrations such as harshness and differential noise input from the accelerator case 14 to the vehicle body via the lower link 11 are reduced to the first. Since the resonance frequency range of the first vibration damping section 26 constituted by the second fluid chamber 20.21 and the first orifice 24 is set to the vibration frequency of the harshness, it is difficult for this harshness to be transmitted to the vehicle body. significantly reduced. On the other hand, the third. Fourth fluid chamber 22.2
Since the resonance frequency range of the second vibration damping section 27 constituted by the second orifice 3 and the second orifice 25 is set to the vibration frequency of the differential noise, transmission of the differential noise vibration to the vehicle body is significantly reduced. Figure 4 shows the vibration transmission force characteristics of the fluid-filled vibration isolator. ) exists. That is, the frequency range (A) to be damped in the low frequency range is a harshness region achieved by the first vibration damping section 26, and the frequency range (B) to be damped in the high frequency range is the harshness region achieved by the second vibration damping part 27. It is clear that these problematic harshness and differential noise are reduced at the same time. Therefore, the noise caused by the differential noise and the muffled noise caused by the harshness transmitted into the vehicle interior are significantly reduced, and the quietness of the vehicle interior is significantly improved. The transmission force characteristic (b) shown by the broken line in Fig. 4 is due to the conventional fluid-filled vibration isolator, and the frequency range to be damped is one, reducing the harshness. When the frequency range to be damped was set, anti-resonance (reflection) of this increased the transmission force in the differential noise region, exacerbating the other problem.

FIG. 5 shows a fluid-filled vibration isolator 10a of another embodiment,
Rubber bushings 12 provided at both ends of the link body 19.
Each of the rubber bushings 12a is provided with a vibration damping section, and in the rubber body 18 of one rubber bushing 12, there are a pair of first. Second fluid chambers 20a, 21a and both fluid chambers 20a,
A first vibration damping section 26a is provided by the first orifice 24a that communicates with the first orifice 21a, and a link body 19 is similarly disposed in the rubber body 18 of the other rubber bush 12a and is opposed in the extending direction of the link body 19 with the inner cylinder 16 in between. The third of the l pair. Fourth
A second vibration damping section 27a is provided by the fluid chambers 22a, L3a and the second orifice 25a. Then, as in the embodiment described above, the frequency range to be damped by the first vibration damping section 26a is set to the harshness region, and the frequency range to be damped by the second vibration damping section 27a is set to the differential noise region. The same functionality as in the example is demonstrated.

6(A), (B), and (C) show another embodiment, in which first and second vibration damping portions 26b are provided in one rubber bushing 12.
. a second vibration damping section 26b;
The rubber bushes 27b are spaced apart from each other in the axial direction of the rubber bush I2, and have different vibration damping directions. That is, the first . Second fluid chamber 20b.

21b is disposed opposite to the extending direction of the link body 19 with the inner cylinder 16 in between, as shown in FIG. Fourth fluid chamber 2
2b and 23b are the inner cylinder 16 as shown in FIG. 6(C).
They are arranged opposite to each other in the extending direction of the link body 19 with the link bodies 19 in between. Therefore, the vibration damping direction of the first vibration damping part 26b is perpendicular to the extending direction of the link body 19, and the vibration damping direction of the second vibration damping part 27b is the extending direction of the link body 19.

Therefore, in this embodiment, vibrations input from different directions can be simultaneously reduced by one fluid-filled vibration isolator 10b. The first vibration damping section 26b has a first orifice 24b formed with a relatively small diameter so that the frequency range to be damped matches harshness vibration, and the second vibration damping section 27b has a first orifice 24b having a relatively small diameter so that the frequency range to be damped matches harshness vibration. It goes without saying that the second orifice 25b is formed to have a relatively large diameter to match the differential noise.

FIG. 7 shows a fluid-filled vibration isolator 10c of still another embodiment, in which a first vibration damping section 26c and a second vibration damping section 27c are separately provided on rubber bushes 12, 12a provided at both ends of the link body 19. In the fluid-filled vibration isolator that has been formed, the first. Second vibration damping section 26c, 2
7c, the vibration damping directions are different from each other. Therefore, in this embodiment as well, as in the embodiment shown in FIG. 6, vibrations input from different directions can be effectively reduced.

In each of the above-mentioned embodiments, the lower link 11 of the four-link suspension is used as a vibration isolator, and the fluid-filled vibration isolator of the present invention is applied thereto. The present invention is not limited to the upper link 11, but may be applied to the upper link 15, and although not shown in the drawings, it goes without saying that the present invention can be applied to vibration isolators such as ennon mounts. Further, the number of vibration damping sections is not limited to two, and three or more may be provided, and by providing more vibration damping sections, the frequency range to be damped can be increased, and the vibration damping effect can be further improved.

Also, the damping frequency may be tuned depending on the orifice length, liquid density, etc.

As described in detail of the invention, in the fluid-filled vibration isolator of the present invention, the two vibration isolators are provided with a plurality of vibration damping sections each having a different damping target frequency. One vibration isolator can simultaneously reduce vibrations in frequency ranges corresponding to the number of vibrations. Therefore, by being able to reduce multiple problematic vibrations at the same time, the frequency range in which vibrations can be damped expands, especially in cases where multiple problematic vibration frequency ranges exist over a wide range, such as in automobiles. It has a remarkable vibration reduction effect.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a fluid-filled vibration isolator according to an embodiment of the present invention, Fig. 2 is a perspective view of a four-link suspension, and Fig. 3 is a fluid-filled vibration isolator. FIG. 4 is a characteristic diagram showing the relationship between the resonance frequency and the orifice diameter of the fluid-filled vibration isolator. FIG. A cross-sectional view showing,
FIG. 6 shows another embodiment of the present invention, in which (A) is a side view of the main part, (B) is a cross-sectional view taken from the line Via-Via in (A), and (C) is a cross-sectional view of the main part. (A) is a sectional view taken from line VIc Vlc in the figure, FIG. 7 is a sectional view showing another embodiment of the present invention, and FIG. 8 is a sectional view of main parts showing a conventional fluid-filled vibration isolator. . 10, 10a, fob, 1Oc--Fluid-filled vibration isolator, 20, 20a. 21b, 20cm...first fluid chamber, 21.21a,
21b, 21cm--second fluid chamber, 22.22a,
22b, 22c...-Third fluid chamber, 23° 23a,
23b, 23c... fourth fluid chamber, 24.24a,
24b, 24c...first orifice, 25.25a
, 25b, 25cm second orifice, 26.26a
, 26b, 26c... 1st vibration damping section, 2 other people Figure 1 Figure 2 Figure 7 Figure 8

Claims (1)

[Claims] (1) Elastically deformable 1 communicated through an orifice
The vibration damping section includes a pair of fluid chambers, and the vibration damping section has a vibration damping section configured by a pair of fluid chambers, and the resonance frequency determining factors such as the fluid mass in the orifice of the vibration damping section and the expansion elasticity of the fluid chamber wall, In a fluid-filled vibration isolator in which the vibration damping target frequency is determined in the arrangement direction, a plurality of vibration damping parts each having a different vibration damping target frequency are provided in one vibration isolator. A fluid-filled vibration isolator featuring: