JPH04136534A - Liquid-sealed vibration proofing device - Google Patents

Abstract

PURPOSE:To change its characteristics in response to input vibration to efficiently reduce vibration by forming a closed space in a vibration proof rubber body, dividing the space into a pair of liquid chambers by a partition wall having throttling passage, and sealing two or more types of compatibility. liquids which differ from each other in specific gravity, and have no CONSTITUTION:When shake-vibration of small amplitude is inputted, the deformation of a vibration proof rubber body 1 is small, the changes in volume of a main liquid chamber A is small, only antifreezing fluid L2 of low viscosity flows through a throttling passage 21, and thus the shake vibration of about 10Hz is efficiently decayed because a device damping factor indicates a maximum. When convulsible vibration of large amplitude is inputted, the vibration proof rubber body 1 is largely deformed, silicone oil L1 having high viscosity ranked next to the antifreezing fluid L2 flows into the throttling passage 21, the dynamic spring constant becomes sufficiently large value in the neighborhood of 10Hz, and thus the scoop-up vibration is efficiently restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid-filled vibration isolator, and in particular to a liquid-filled vibration isolator that changes characteristics according to the amplitude of input vibration to effectively prevent vibration transmission over a wide range. Regarding vibration isolators.

[Prior art] A liquid-filled vibration isolator is effective by forming a pair of liquid chambers in a vibration isolating rubber body that supports a vibrating body, and allowing sealing liquid to flow between the two liquid chambers through a constricted channel. It provides vibration damping. When such a liquid-filled vibration isolator is used in a vehicle engine mount, various vibrations are input from the engine depending on the driving condition of the vehicle, and in order to effectively reduce these input vibrations, it is necessary to Therefore, it is necessary to optimally select the dynamic spring constant and damping coefficient of the device.

[Problems to be Solved by the Invention] Conventionally, as a method of changing device characteristics in response to input vibration, a method in which a part of the partition wall that partitions a liquid chamber is made into a movable wall, and a constricted flow path with a different length are selected. There are devices that open and close, but all of them require mechanical operating parts, which makes the device structure complicated.

The present invention is intended to solve such problems, and aims to provide a liquid-filled vibration isolator that can effectively reduce various input vibrations and can change device characteristics without complicating the device structure. .

[Means for Solving the Problems] To explain in detail the present invention, a liquid filled vibration isolator forms a sealed space in a vibration isolating rubber body 1 that supports a vibrating body, and
, L2, and the sealed space is divided into a pair of liquid chambers A and B by a partition wall 2 having a throttle flow path 21, and the filled liquids L1 and L2 have different specific gravity and are compatible with each other. It is composed of two or more liquids L1 and L2 without any

[Function] In the vibration isolating device having the above configuration, two or more sealing liquids Ll
, L2 has a smaller specific gravity, Ll, moves upward, and a larger specific gravity, L2, moves downward.

If the liquid amount is set so that one type L2 of these sealing liquids is near the throttle channel 21, the amount of liquid movement due to the deformation of the liquid chamber A is small when a small amplitude vibration is input, so that
Only one type of liquid L2 flows through, and the characteristics of the device are determined by the characteristics of this liquid.

When a large-amplitude vibration is input, the liquid chamber A is greatly deformed, the amount of liquid movement increases, and the other type of liquid L1 flows through the throttle channel 21 following the above-mentioned - type of liquid L2, and this liquid The device characteristics are changed due to the difference in the characteristics of L1.

In this way, without having any mechanical operating parts, the device characteristics can be switched to the optimum device characteristics according to the vibration amplitude, and an effective vibration reduction effect can be achieved.

[First Embodiment] In FIG. 1, a vibration isolating rubber body 1 has a thick-walled cylindrical shape whose diameter expands downward, and its upper opening is closed by a top plate 4 that projects downward in a chevron shape. The upper end of a cylindrical side plate 5 is joined to the lower opening edge of the vibration isolating rubber body 1, and a partition wall 2 is inserted and fitted into the side plate 5 to close the lower opening of the vibration isolating rubber body 1. A main liquid chamber A is formed above. A thin rubber sheet 3 is disposed below and along the partition wall 2, and its outer periphery is in close contact with the lower outer periphery of the partition wall 2 to form an auxiliary liquid chamber B below it.

A throttle channel 21 is formed on the outer periphery of the partition wall 2 to communicate the upper and lower main liquid chambers A and auxiliary liquid chamber B, and two types of liquids L1 are contained in both liquid chambers A and B that communicate with each other. , L2 are enclosed. That is, one of the filled liquids L1 and L2 is silicone oil, and the other is an antifreeze liquid mainly containing ethylene glycol. While the specific gravity of the antifreeze L2 is 1.1, that of the silicone oil L1 is 0.98, and when these are mixed, the silicone oil L1 moves above the antifreeze L2. When the ratio between the two is adjusted, the antifreeze liquid L2 enters into the main liquid chamber A above the partition wall 2, creating a liquid boundary R1 in the main liquid chamber A, as shown in the figure. here,
The silicone oil L1 used has a kinematic viscosity of about 200 cst, which is larger than that of the antifreeze L2.

The vibration isolator is fixed to the vehicle frame by bolts on a bottom plate 6 disposed below the rubber sheet 3 and connected to the lower end of the side plate 5. It is bolted to the plate 7.

When engine vibration is input to the vibration isolator, the volume of the main liquid chamber A changes due to the deformation of the vibration isolator 1, and the sealing liquid flows into the throttle flow F.
I! It flows through I21 and generates a vibration damping force, and the internal pressure of the main liquid chamber A increases to generate a large spring force. The dynamic spring constant of the device in this case exhibits frequency characteristics as shown in FIG. 2, depending on the characteristics such as the viscosity and specific gravity of the liquid passing through the throttle channel 21.

The viscosity of the lines w, x, y, and z in the figure increases in this order, and when the viscosity is small, the dynamic spring constant is small on the low frequency side,
A large extreme value appears on the high frequency side, and as the viscosity decreases, the absolute value of the extreme value becomes smaller.

Now, when shake vibration with a relatively small amplitude is input, the amount of deformation of the vibration isolating rubber body 1 is small, and therefore the change in volume of the main liquid chamber A is small, so the antifreeze liquid L2 with low viscosity
only flows through the throttle channel 21. The device characteristics in this case are as shown in FIG. 3, and shake vibrations around 10 Hz are effectively attenuated and reduced by the device damping coefficient (broken line in the figure) showing a maximum. In addition, in the figure, the solid line indicates the characteristic of the dynamic spring constant of the device.

When a hiccup vibration with a relatively large amplitude is input, the vibration isolating rubber body 1 is greatly deformed, and accordingly, the volume of the main liquid chamber A changes greatly, and a liquid with a high viscosity, following the antifreeze liquid L2, is introduced into the throttle channel 21. The silicone oil L1 flows, and as a result, the device characteristics become as shown in FIG. In this state, as can be seen from the figure, the device dynamic spring constant (solid line in the figure) takes a sufficiently large value around 10 Hz, and the shudder vibration is effectively suppressed and reduced.

[Second Example] In place of the above silicone oil, a material having a specific gravity higher than that of antifreeze (
Fluorine oil (specific gravity 1.7 to 2.0) and high viscosity (for example, DuPont product name Krytox 143) may be used; in this case, as shown in Figure 5, fluorine oil L3 is used as an antifreeze agent. L2 moves downward, and a liquid boundary R2 is created in the sub-liquid chamber B.

This configuration also provides the same effects as the first embodiment.

[Third Example] As shown in FIG. 6, silicone oil Ll, antifreeze L2
, fluorine oil L3 can be sealed. In this case, the antifreeze liquid L2 is located in the middle layer near the partition wall 2, the silicone oil L1 is located in the upper layer, and the fluorine oil L3 is located in the lower layer.

According to this configuration, when the main liquid chamber A contracts when a large vibration is input, the silicone oil L1 flows, and when the main liquid chamber A expands, the fluorine oil L3 flows through the throttle channel 21 following the antifreeze liquid L2. An effective vibration reduction effect is achieved.

[Effects of the Invention] As described above, according to the liquid-filled vibration isolator of the present invention, by sealing liquids having different specific gravity and incompatibility with each other into the liquid chamber, a mechanical operating part is provided and the structure is complicated. Optimize the device characteristics according to the type of input vibration without causing
Vibration can be effectively reduced.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention.
The figure is an overall sectional view of the vibration isolator, Figure 2 is a frequency characteristic diagram of the dynamic spring constant of the device, Figures 3 and 4 are frequency characteristic diagrams of the dynamic spring constant and damping coefficient of the device, and Figure 5 is a diagram of the frequency characteristic of the dynamic spring constant of the device. 6 is an overall sectional view of a vibration isolator according to a second embodiment of the present invention, and FIG. 6 is an overall sectional view of a vibration isolator according to a third embodiment of the invention. 1... Vibration-proof rubber body 2... Partition wall 21... Throttle channel 3... Rubber sheets A, B... Liquid chambers Ll, L2, L3... Filled liquid Fig. 1 Fig. 2 Figure Number of limbs (Hz) Figure 5 Figure 3 2゜Frequency (Hz) Frequency (Hz) Figure 6

Claims (1)

[Claims] A sealed space is formed in a vibration isolating rubber body that supports the vibrating body, and a liquid is sealed in the sealed space, and the sealed space is divided into a pair of liquid chambers by a partition wall having a constricted flow path, and the sealed liquid is sealed in the sealed space. ,
A liquid-filled vibration isolator comprising two or more types of liquids having different specific gravities and being incompatible with each other.