JPS612936A - Vibro-isolator - Google Patents

Abstract

PURPOSE:To prevent transmission of engine vibration to a car body by use of an effective manner by using such a vibro-isolator that produces a damping force in a low frequency corresponding to that of engine vibration and, on the other hand, restrains the dynamic magnification under 1.5 time by use of the resonant operation of fluid if vibration has frequency within the specific frequency range higher than said low frequency. CONSTITUTION:A liquid chamber of which a part is made of an elastic material such as rubber 22 or the like functioning as a main vibration suppressing means is divided into an upper liquid chamber 37A, a middle liquid chamber 37B and a lower liquid chamber 37C. The upper liquid chamber 37A and the middle liquid chamber 37B are communicated with each other by a primary restricting passage while the middle liquid chamber 37B and the lower liquid chamber 37C are communicated with each other by a secondary restricting passage. The secondary restricting passage consists of an orifice 64 which has a long axial length and a small sectional area for the purpose of attenuating vibration of low frequency corresponding to that of engine vibration. The primary restricting passage consists of a passage 39 which has a large sectional area for the purpose of suppressing vibration of a high frequency which is approximately 20Hz.

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] Vibration isolating devices, generally called vibration isolating rubber, are used, for example, in engine mounts of automobiles to absorb vibrations from the automobile engine and prevent them from being transmitted to the vehicle body.

For this reason, in order to make the vibration transmission force as low as possible at each frequency and to suppress the vibration of the engine that occurs at 10 to 20Hz, the following steps were taken: ', ] A damping force is generated near the wave number A-1. Currently, common engine mounts are manufactured that obtain damping force at low frequencies of about 10 to 20 Hz.

However, in such a conventional motor vehicle, it is difficult to absorb vibrations at specific frequencies other than engine vibrations.

[Objective of the Invention] The present invention takes into consideration the above facts, and generates a damping force at a low frequency corresponding to engine vibration, and in a specific frequency range higher than this, uses fluid resonance to generate a dynamic magnification. It is an object of the present invention to obtain a vibration isolating device which suppresses vibration to 1.5 times or less and effectively prevents vibration from being transmitted to the vehicle body.

[Summary of the Invention] In the vibration isolating device according to the present invention, a hollow chamber mainly for vibration absorption made of a hollow molded body of an elastic material is used as a liquid chamber, and this hollow chamber is connected to three in series by two restricting passages. The first restriction passage, which is divided into small liquid chambers and located on the vibration pressure transmission side, has a sufficiently large diameter, and the second restriction passage is sufficiently smaller in diameter than the first restriction passage. By forming the length short, a damping force against low frequencies is generated in the second restriction passage, and in the first restriction passage, the dynamic magnification is suppressed to 1.5 times or less even at relatively high frequencies due to resonance of the liquid. It has become.

[Embodiment of the Invention] FIG. 1 shows a sectional view of a vibration isolator to which a first embodiment of the invention is applied. This vibration isolator is now used in automobiles as an engine mount.

The bottom cylinder 10 of this vibration isolator is fixed to the inner side of the axially intermediate portion by caulking the peripheral edge of the ring plate 12. The ring plates 1 and 12 sandwich the periphery of the lower diaphragm 14 between them and the bottom cylinder stepped portion 10A formed directly below. This lower diaphragm 14 forms an air chamber 16 between R (the bottom plate 1OB of the tube 10).
A through hole may be formed in B to communicate with the outside.

One -1 end of the bottom cylinder 10 is fixed to the lower end of the connecting cylinder 20 via the l-partition plate 18.

The connecting tube 20 is widened at one end, and the lower end of the rubber 22, which serves as a vibration absorber, is vulcanized and bonded. rubber 22
It is also possible to use other elastic materials instead.

The upper end of this rubber 22 is vulcanized and bonded to a plywood 24, and a base plate 24 is fixed thereto. The plywood 24 is for mounting an engine (not shown), and the bolts 26
This allows the engine to be fixed to the plywood 24.

A flange 28 is projected from the outer circumference of the connecting tube 20, and a port 30 provided on the flange 28 is used for fixing to a vehicle body (not shown).

A sealed space formed by the bottom tube 10, lower diaphragm 14, connection tube 20, rubber 22, and base plate 24 is a liquid chamber into which a liquid such as water is injected.

The upper floor wall plate 18 is divided into a liquid chamber 37A and a middle liquid chamber 37B, and these liquid chambers are communicated through a cylindrical portion 38 fixed to the center.

At the top of the diaphragm 14, a lower corner wall plate 56 is attached to the bottom tube 10.
The surrounding area is clamped and fixed. This lower corner 1V board 56 has a cylindrical part 58 and a ceiling part 60, and has a raised central part.
The liquid chamber is divided into a middle liquid chamber 37B and a lower liquid chamber 37C.

As a result, the -I liquid chamber 37A, the middle liquid chamber 37B, and the lower liquid chamber 37C are arranged in series.

Further, an abutment plate 62 shown in FIG. 2 is fixed to the cylindrical portion 58 and ceiling portion 60 of the lower corner wall plate 56, and an orifice 64 is formed by the four ring-shaped portions 63. This orifice 64 is a communication hole 66 bored in the lower corner wall plate 56.
The middle liquid chamber 37B and the lower liquid chamber 37C are communicated with each other through a communication hole 68 formed in the contact plate 62.

Here, the cylindrical portion 38 is arranged closer to the vibration pressure transmission side than the orifice 64, that is, closer to the plywood 24, and the orifice 64 has a smaller diameter and a longer axial length than the cylindrical portion 38 (the axial length is equal to the cross-sectional area). 5 borrowed scenery"-).

Next, the operation of this embodiment will be explained.

The flange 28 is mounted on the vehicle body and fixed to the vehicle body via the bolts 30, and the assembly is completed when the automobile engine is mounted on the base plate 24 by the bolts 26.

When installing the engine, the engine's own weight should be
As a result, the pressure in the l-liquid chamber 37A increases by A. This h l pressure is transmitted to the middle liquid chamber 37B via the cylindrical portion 38 and to the lower liquid chamber 37C via the orifice 64, so that the lower diaphragm 14 is displaced in a direction that reduces the air chamber 16.

When the engine is running, the vibrations that occur in the engine are transmitted to the plywood 24.
transmitted via. The rubber 22 can absorb vibrations by a damping function based on internal friction.

When the frequency of vibration is low, for example, the frequency is 5 to 20Hz,
For vibrations with an amplitude of ±0.5 to 1.0 mm, the axial length is large and the restricted passage, that is, the orifice 6, has a small cross-sectional area.
The vibration damping effect is improved by the damping effect based on the viscous resistance that occurs when the tube passes through the tube. In this case, since the cylindrical portion 38 has a large cross-sectional area, there is almost no damping effect in this portion.

This low-frequency, large-amplitude vibration absorption has a large vibration absorption effect because the orifice 64 is C-shaped and a long restricted passage is formed.Also, when the contact plate 62 is attached to the lower corner IV plate 56 by welding etc. The length of the orifice 64 can be arbitrarily adjusted by changing the relative angle around the axis.

Further, when the vibration of the engine has a high frequency, for example, when the frequency is 20 Hz or more, the amplitude is small, and the orifice 64 may become clogged. However, since the cylindrical portion 38 has a large cross-sectional area, the liquid inside the cylindrical portion 38 causes liquid column resonance without clogging, and the shape and size of the cylindrical portion 38 allows the specific high-frequency vibrations to be appropriately absorbed. .

The bottom tube 10 in the embodiment L may be made of metal or a flexible elastic body. The more flexible the bottom cylinder is, the more flexible the cylinder part 38 becomes.
Since the resonant frequency generated in the orifice 64 becomes lower, the resonant frequency can also be selected using this.

Next, the size of the cylindrical portion 38 in the first embodiment will be explained. The volume of the upper liquid chamber 37A changes by Acrn' when the rubber 22 is deformed and bent by 1 cm, and the effective diameter of this two liquid chamber is increased. am and the effective area is A crn'
(= (Do /2) 2Xπ), assuming that the length of the cylindrical portion 38 is Lcm and the diameter is Dcm, D/Do is larger than 1/3 and L/D2 is smaller than 1/3 (1/cm). is necessary.

When this D/Do is larger than 173, the cylindrical portion 38 tends to become clogged at high frequencies, and when the cylindrical portion length < L/D2 is larger than 173, a decrease in dynamic magnification occurs in the low frequency region. become.

By satisfying the above conditions, low dynamic magnification can be obtained in the high frequency range of 100 to 200 Hz.

FIGS. 3A and 3B show the spring constant and loss coefficient with respect to frequency in the first embodiment, and a large damping force can be obtained at any frequency.

FIG. 4 shows a second embodiment of the present invention, in which the cylindrical portion 38 of the previous embodiment is removed and the ring plate 18 has an opening 18A formed therein.

Also, rubber 7, which is harder than the rubber 22, is provided at the -1 section of the base plate 24.
0. An engine mounting plate 71 is attached, which makes it possible to suppress the rise in the spring constant at the time of liquid resonance to a low level, as shown in FIG.

This rubber 70 can also be attached to the bottom cylinder 10 side.

FIG. 6 shows a third embodiment of the present invention, in which a circular hole is bored in the ceiling 60, and a U-shaped flange 74 of a movable plate 72 is fitted into the circular hole. It becomes. Therefore, the movable plate 72 has a U-shaped flange 74 located slightly below the circumferential edge of the circular hole in the ceiling 60 (0, 1-).
It is possible to move a small amount v1 (approximately 0.05 mm), thereby suppressing pressure rise during high frequency vibration. This diaphragm 72 is connected to the lower soaking chamber 37C and the middle liquid chamber 37.
The mounting position is not limited as long as it is provided between the

FIG. 7 shows a fourth embodiment of the present invention, in which a U-shaped flange 74 is attached around a lower corner wall plate 56, and this lower corner wall plate 56 can be slightly vibrated with respect to the bottom cylinder 10. Therefore, the same effect as in the above embodiment can be obtained.

FIG. 8 shows a vibration isolator according to a fifth embodiment of the present invention. In this embodiment, a rubber membrane 76 is removed in place of the movable plate 72 of the third embodiment, and a wire cord is stretched inside the rubber membrane 76 for example, so that its displacement can be changed. The amount is limited and the movable plate 72
It is designed to have a similar role.

FIG. 9 shows the characteristics of FIGS. 6, 7, and 8.

A sixth embodiment of the present invention is shown in FIG.
The elastic force of the rubber 22 is adjusted by inserting a hering 78 into the rubber 22 of the embodiment shown in the figure.

FIG. 11 shows a seventh embodiment of the present invention, in which a regulating plate 80 integrally projected from a plywood 24 is formed with a regulating portion 82 bent at a right angle. A stopper rubber 84 is attached to each. As a result, it faces the rubber 86 attached around the connecting tube 20. Therefore, in this embodiment, the amount of movement of the plywood 24 in the lateral direction can be limited.

FIG. 12 shows an eighth embodiment of the invention. In this embodiment, an abutment plate 62A similar to the ring plate 12 is provided to the ring plate 18 to form an orifice 88. Also in this embodiment, the orifice 88 has a larger cross-sectional area and a shorter axial length than the orifice 64.

Figures 13(A) and (B) show the 5th section shown in Figure 8.
Experimental results of Examples are shown. In this case, the liquid chamber 37A contains 70 cc of antifreeze, the middle liquid chamber 37B, and the upper liquid chamber 37.
Each G is filled with 30cc of antifreeze, the air chamber 16 is filled with 70cc of air, and the rubber 22 has a dynamic spring constant of 120kg7.
cm, j a nδ (loss coefficient) = 0.1, and the bottom cylinder lO has the same bulk elasticity as the rubber 22 as an elastic body,
A spring with a dynamic spring constant of 220 kg/cm is used.

Further, the cylindrical portion 38 had a diameter of 4 cm and a length of 0.5 cm, and the orifice 64 had a diameter of 0.8 cm and a length of 5.0 cm. As shown in FIG. 13, the results of this example determined in this way show that tan δ is
±0.05m due to the movable plate.
There is no rise in the dynamic spring constant near 10 Hz with small vibrations of about m, and tan δ does not occur near 10 Hz. In addition, by having the cylindrical portion 38, the
The spring constant can be significantly reduced at Hz.

[Effects of the Invention] As explained above, in the vibration isolating device according to the present invention, the hollow chamber mainly for vibration absorption made of the hollow molded body of the elastic material 1 is used as the liquid chamber, and this hollow chamber is used as the liquid chamber. by 3
The first restriction passage located on the vibration pressure transmission side has a sufficiently large diameter;
Since the second restriction passage is sufficiently smaller in diameter than the first restriction passage and has a shortened axial length, it has an excellent effect of being able to absorb vibrations over a wide range of frequencies.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the first embodiment of the present invention, Fig. 2 is an exploded perspective view showing the structure of the lower corner wall plate, and Fig. 3 shows the results of the first embodiment, the spring constant and tan δ versus frequency. 4 is a sectional view showing the second embodiment of the present invention, FIG. 5 is a diagram of the spring constant versus frequency showing the results of the second embodiment, and FIGS. 6 to 8 are diagrams showing the results of the second embodiment. 9 is a diagram of spring constant versus frequency showing the results of the 3rd and 4th embodiments. FIG. 13 is a cross-sectional view showing the sixth to eighth embodiments, and a line diagram showing experimental results based on the fourth embodiment of the present invention. 22.1 Rubber, 24... Base plate, 37A... Upper liquid chamber, 37B... φ middle liquid chamber, 37C... Lower fist liquid chamber, 38... Cylinder part, 641. Orifice.

Claims (1)

[Claims] (1) A hollow chamber mainly made of a hollow molded body of an elastic material that absorbs vibrations is used as a liquid chamber, and this hollow chamber is divided into three small liquid chambers arranged in series by two restriction passages, and vibration A vibration isolator characterized in that the first restriction passage located on the pressure transmission side has a sufficiently large diameter, and the second restriction passage has a sufficiently smaller diameter than the first restriction passage and a short axial length.