JPH0257741A - Vibration preventing device - Google Patents

Abstract

PURPOSE:To prevent wears of particles and the wall of a vibration preventing device by hydrolyzing and polymerizing metal alcoxides or derivative therefrom, dispersing spherical particles containing electrolytic solution obtained therefrom in an electrical insulative liquid, and thereby forming an electrical viscous fluid. CONSTITUTION:Metal alcoxides, for ex. Si(OC2H2), are hydrolyzed and polymerized, and spherical silica is separated from alcohol solution and dried to provide spherical particles containing electrolytic solution. These spherical particles are dispersed in electrical insulative liquid such as silicon oil, wherein the amount of used particles shall normally be 5-50vol.% of the electric insulative liquid. This electrical viscous fluid is used to vibration preventing device, and the viscosity of the liquid in a piping 4 is varied by impressing voltage on electrodes 10, 11, and thereby the damping performance and dynamic rigidity are adjusted. Therein the wall and particles are substantially free of wear even after oscillative reversals corresponding to running for 100 thousands of kms have been applied to this vibration preventing device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration isolator that prevents various harmful vibrations.

BACKGROUND OF THE INVENTION Conventionally, one type of vibration isolator is known that uses an electrorheological fluid as a vibration damping medium.

Here, the electrorheological fluid refers to the effect of applied voltage (OFF,
It is a fluid that exhibits the so-called electrorheological effect, in which its apparent viscosity changes rapidly and reversibly depending on the voltage (on, voltage change). Therefore, by changing the applied voltage according to the frequency of vibration from the vibration source, the viscosity of the electrorheological fluid can be changed to absorb vibrations. Conventionally, as one type of electrorheological fluid, one obtained by vigorously stirring an electrically insulating liquid, fine particles adsorbing or containing ions, and a small amount of water is known.

The electrorheological effect in the above fluid can be considered as follows. In other words, water moves into the fine particles through the 5 strong stirring process to create an electrolyte solution, and when a voltage is applied, the ions in the electrolyte solution thus obtained move and become unevenly distributed in the fine particles, causing the particles to separate. do. The fine particles aggregate with each other due to electrostatic attraction based on the separation described above, and as a result, an electrorheological effect is developed.

By the way, in a vibration isolating device using an electrorheological fluid, it is common to utilize a change in viscosity when the fluid passes through an orifice-shaped gap.

Therefore, wear between the particles, which are the dispersed phase, and the walls of the vibration isolator becomes a problem.

[Object of the Invention] An object of the present invention is to provide a vibration isolating device that improves the above-mentioned problems.

[Structure of the invention] Hereinafter, the present invention will be explained in detail according to the attached figures.

FIG. 1 is a conceptual sectional view of the vibration isolator of the present invention. A housing whose upper and lower parts can be deformed and restored by changes in pressure is divided into upper and lower parts by an orifice having plate electrodes on the upper and lower sides, each of the upper and lower compartment spaces is filled with electrorheological fluid, and the housing is placed at the upper part of the housing. This vibration isolator is configured to change the applied voltage according to the frequency of vibration from the vibration light generation device.

In the present invention, the electrorheological fluid is composed of electrically insulating liquid containing spherical particles containing an electrolyte solution obtained by hydrolyzing and polycondensing a metal alkoxide or a derivative thereof.

As metal alkoxide, r Metal Alk
oxides (D, C, Bradley, R, C, M
co-authored by Ehrotra, D, P, and Gaur) Acade
Various alkoxides described in mic Preas 1987J can be used, but typical examples include alkoxides such as Si, Ti, and Zr, and Ba-T.
i, 5r-Ti, Pb-Tj.

Examples include complex alkoxides such as Pb-Ti-Zr and Li-Nb.

Hydrolysis of metal alkoxides is generally carried out by mixing an alcohol solution in which the alkoxide is dissolved with an alcohol aqueous solution, but by appropriately adjusting the hydrolysis rate, the amorphous form of the metal oxide can be substantially removed. It can be precipitated as spherical particles. The hydrolysis rate is usually adjusted by the molar ratio and concentration of alkoxide and water in the reaction system, and the amount of hydrolysis catalyst (alkali or acid, etc.) added as necessary. Conditions cannot be determined unconditionally because they vary depending on the type of alkoxide, but for example, Si
(OCt Hs ) T 1COCt fEs )
a, ZrCOC*Hs)4 (In case of D, usually [H!01/[alkoxide 1 molar ratio is 1~
150. More preferably l-1oo, the concentration of alkoxide (mol/l) is 0.05 to 10, more preferably 0.05 to 5, and the concentration of water (mol/l) is 0.
．． A range of 1 to 20, more preferably 0, INto is preferred.

FIG. 2 shows S i (QCs Ha ) in the example.
This is a scanning electron micrograph (10,000x magnification) of spherical silica particles obtained by hydrolysis of a.As is clear from the figure, each particle is spherical and the particle size distribution is sharp. be.

Spherical silica is obtained by separating the solid content from an alcohol solution by filtration or centrifugal sedimentation, and drying it using a rotary evaporator or the like, and has an average particle size in the range of 0.05 to 2 μm.

The spherical particles must contain an electrolyte solution, and the ions in the solution produce an electrorheological effect based on the above-mentioned principle.

The electrolyte constituting the electrolyte solution is not particularly limited as long as it dissociates into ions in a polar solvent such as water; for example, N Hs, Na OH, Na ClLiC.
1.BaOs,Cab,MgSO4,FO(NO
Examples include inorganic compounds such as sL, and ionic surfactants such as sodium sulfonate, sodium carboxylate, sodium alkylbenzenesulfonate, sodium polystyrene sulfonate, fatty acid calcium salt, and formalin condensate of naphthalenesulfonic acid.

As the solvent constituting the electrolyte solution, any scratchy solvent can be used as long as it can sufficiently dissolve the electrolyte used.

The concentration and content of the electrolyte solution are appropriately selected within a range that does not cause conduction when an electric field is applied.
It is usually selected from the range of 0.11 to 90% by weight, preferably 5 to 50% by weight, and the content is selected from the range of 0.1 to 20% by weight, preferably 1 to 10% by weight.

As mentioned above, the hydrolysis and polycondensation of the metal alkoxide can be carried out in the presence of the NHs7i catalyst, and in such a case, the catalyst can be used as it is as an electrolyte. That is, after hydrolysis and polycondensation of the metal alkoxide, the spherical silica is separated from the alcohol solution and dried. Decrease is 0.1-20! l! %, preferably 1 to 10% by weight, yields spherical particles containing an electrolyte solution in the above range. In addition, the above heating weight reduction is 1
This is a value obtained by differential thermal analysis at a heating rate of 0° C./min.

Of course, it is also possible to completely carry out the above-mentioned drying or washing with water before drying, and then add the electrolyte solution. In such cases, it is preferable to use a solvent with a higher boiling point than water as the converting solvent constituting the electrolyte solution.
In other words, if an electrorheological fluid that uses a low-boiling point solvent such as water is used for a long period of time in an environment that generates heat due to high temperatures or high shear forces, the solvent will volatilize and break down, resulting in insufficient Although there is a problem that the electrorheological effect is no longer expressed, such problems can be solved at once by using a high boiling point solvent. Examples of the high boiling point sparse solvent used for the above purpose include glycol and ethanolamine, among which ethylene glycol is preferably used. At this time, the method of impregnating the electrolyte solution can be carried out by mixing the spherical particles, electrolyte, polar solvent, and electrically insulating liquid in a ball mill for several hours, or by impregnating the spherical particles with the electrolyte solution. .

The electrically insulating liquid used is one that can stably disperse spherical particles, has high insulation resistance, and does not dissolve the electrolyte solution, and specifically, silicone oil, transformer oil, engine oil, ester, paraffin, olefin, or Appropriately selected from aromatic hydrocarbons and the like. The amount of spherical 4-shaped particles used in electrically insulating liquid is usually 5 to 50% by volume.
is used, preferably 10 to 40% by volume.

As a dispersion method, a general mixing and dispersing machine such as a ball mill or an ultrasonic dispersion machine can be used.

To measure the electrorheological effect, use a coaxial double cylinder rotational viscometer to determine the amount of increase in shear stress at the same shear rate (1825 ec-') when a voltage is applied between the inner and outer cylinders, and calculate this as the viscosity. This can be done by converting it into a change.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

['X Example] This vibration isolator has upper chambers l hydraulically connected to each other by a pipe 4 running through an intermediate plate 1O111, which will be described later.
and a lower chamber 2. The upper chamber l is formed by a thick hollow conical chamber wall 5 made of rubber-elastic material, which is connected on the upper side to a support plate 6 to which, for example, an engine is fixed via bolts 7, and on the lower side to a support plate 6 to which, for example, an engine is fixed. It is connected to the retaining flange 8.

The pipe 4, which hydraulically connects the two chambers 1, 2 in the intermediate plate 3, is formed by two metal plates lo, 11, which are inserted into the corresponding hollow chambers of the intermediate plate 3. are spaced apart from each other, and the spacing and width determine the cross-sectional area of the pipe 4. A passage 12 to the upper chamber 1 is provided at one end of the plates io, tt, and a passage 13 to the lower chamber 2 is provided at the other end.

The plate 10, which acts as an upper bridge, is connected to an adjustable power source 15 via an externally led wire 14, while the lower electrode 11 is connected to ground potential.

Both chambers 1, 2 were filled with an electrorheological fluid produced in the following manner.

That is, Si (OCx Ha ), 186.0 g
and 28
Heavy 4% NH,OH aqueous solution 223.6g, water 173.9g
B dissolved in 1999.5 g of ethyl alcohol
The standard deviation of the diameter of 0 particles was 1.05 when the liquid was mixed and silica particles with a diameter of 0.56 μm were precipitated. The particles of this slurry were separated according to a conventional method and dried under vacuum at 100° C. for 1 hour to obtain particles in a powder state. This particle is NHs
(1.3% by weight), water (4.1% by weight), ethanol (
0.6% by weight), and the weight loss when heated in air at 200°C was 6%.
1 g was added to 32.8 g of silicone oil (FOES), and the mixture was dispersed and mixed in a ball mill for 12 hours. Using a coaxial double cylinder rotational viscometer for the electrorheological fluid thus obtained, the shear stress was measured at the same shear rate (162 sec) when voltage was applied between the inner and outer cylinders (distance between 1 mm, temperature 25°C).

The results obtained are shown in FIG.

This electrorheological fluid first acts like an ordinary liquid in the present vibration isolator and, during vibrations of large amplitude and low frequency, flows through the pipe 4 into the upper chamber 1 and also into the lower chamber 2, in which case it flows into the pipe 4. A certain amount of liquid displacement results in a corresponding throttling effect. When a voltage is applied to the electrodes 10 and 11, the viscosity of the liquid in the pipe 4 changes, so this vibration isolator exhibits different damping performance. It becomes so stiff as to make liquid exchange through the gas-viscous fluid tube 4 almost impossible. This means that by controlling the viscosity of the liquid, the damping performance as well as the dynamic stiffness of the engine support can be adjusted and adapted to any arbitrary load situation.

After subjecting the vibration isolator to the vibration frequency equivalent to running 100,000 km, we checked for abrasion from the wall and particle abrasion, and found almost no abrasion.

[Effects of the Invention] As described above, the present invention provides a vibration isolator that is more stable than the vibration isolators disclosed in the prior art and does not require any moving parts over a wide range. give.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vibration isolator according to the present invention. l, 2-11 room, 3-m-intermediate plate, 4-m-piping, 1O
111---Plate electrode, 12, 13-11 passage, 1
5 - Power source Figure 2 is a scanning electron micrograph of spherical silica particles used in Examples. FIG. 3 is a graph showing the thickening effect of the electrorheological fluid of the present invention with respect to the applied electric field, and the horizontal axis is the applied electric field (kv/mm
), the vertical axis is the viscosity (poise). Figure 1

Claims (1)

[Claims] (1) A housing whose upper and lower parts can be deformed and restored by pressure changes is divided into upper and lower parts by an orifice having plate electrodes on the upper and lower sides, and each upper and lower compartment space is filled with electrorheological fluid, and the upper part of the housing is In a vibration isolator configured to change an applied voltage according to the frequency of vibration from a vibration generator mounted on a vibration isolator, the electrorheological fluid is composed of an electrically insulating liquid and fine particles dispersed therein, A vibration isolating device characterized in that the fine particles are electrorheological fluid, which are spherical particles containing an electrolyte solution obtained by hydrolyzing and polycondensing a metal alkoxide or a derivative thereof.