JPS58130182A - Sound-absorbing material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound absorbing material used in an exhaust silencing device for an internal combustion engine.

Conventionally, sound absorbing materials used in exhaust silencing devices for internal combustion engines include glass coolers, porous ceramic bodies, porous metal bodies, and the like. However, when these materials are used as sound-absorbing materials, when an internal combustion engine is operated, tar and soot, which are combustion residues of fuel such as gasoline, adhere to the surface and cause clogging sand in a relatively short period of time, reducing the sound-absorbing performance. In many cases, the noise level was reduced, the noise became intensified, and the fuel efficiency of the internal combustion engine was also adversely affected. In addition, when glass cooling or porous ceramic materials are used as sound absorbing materials in exhaust silencers for internal combustion engines, the pressure of the exhaust gas is high and the vibrations are large, resulting in the sound absorbing materials becoming powdered or damaged. Sometimes it becomes completely useless. and,
When a porous metal body is used, the temperature of the exhaust gas inside the silencer is as high as 400 to 800°C, and the exhaust gas contains corrosive sulfur oxides and nitrogen oxides, so unless a special heat-resistant alloy is used], Corrosion deterioration due to high-temperature oxidation becomes significant, causing clogging due to corrosion products), and once the skeleton of the porous body corrodes and disappears, it is inevitable that it will no longer be useful as a sound absorbing material. Since the basic characteristic of porous metal bodies is that the pore diameter is relatively large, there have been disadvantages such as the absence of any material with good sound absorption performance. Conventional sound-absorbing materials have major drawbacks as described above, and none of them can be put to practical use as exhaust silencing devices for internal combustion engines.

This invention eliminates the drawbacks of the conventional ones, has good sound absorption performance, and has an IK that is clogged with tar and soot.
The present invention provides a sound-absorbing material for an exhaust silencer that prevents deterioration of sound-absorbing performance caused by noise and can withstand high-temperature oxidation.

That is, the sound absorbing material of the present invention uses a porous metal material as a sound absorbing base material without fear of pulverization or breakage, suppresses clogging caused by tar and soot, improves its sound absorbing properties, and uses K. Contains a low-temperature oxidation catalyst and a solid acid catalyst that have three main purposes: to prevent corrosion deterioration caused by high-temperature oxidation, and also contains butted graphite to prevent soot from adhering to the surface of the sound-absorbing base material. A heat-resistant binder is applied to a porous metal sound-absorbing base material.

Hereinafter, the present invention will be explained in detail according to examples.

[Example 1. ] As a metal porous sound-absorbing base material, a foamed metal manufactured by Juden Electric Co., Ltd. (trade name: Celmet, Nil&!, thickness 5 tx), as shown in FIG. (Single side) K1 following composition example 1. A kneaded product obtained by mixing the above composition in a ball mill for about 80 minutes was uniformly applied by spraying. In FIG. 1(A), (1) is the skeleton of the metal porous body, and (2) h-vacancies. 1 more 80℃
After drying at 550° C. for 80 minutes, the film was cured by baking at 550° C. for 80 minutes. According to the inventor's experiments, WFI that applies crosstalk
However, if the amount applied is too large, the sound absorption properties may deteriorate, so care must be taken.

(Composition Example 1.) Low-temperature oxidation catalyst: Iron oxide 8fi% Copper oxide 1stlk% Solid Shun catalyst: Activated clay 121fiM
& IJ: aluminum phosphate) 25
11%: Jll JI7) 101111% Additives: Alumina, Guite, Water 27% by weight
Low surface energy material: fluorinated graphite 511%
In addition, additives have the effect of improving the adhesion and film performance of the coating material, increasing the strength after the coating film is formed and the adhesion performance to the underlying porous material, as well as having the property of making the film porous. It is something that you have.

Figure 1 (B
) The configuration is as shown in the enlarged cross section.

That is, (3) consists of particles of a low-temperature oxidation catalyst dispersed on the surface of the skeleton (1) and in the pores (2) of the porous metal body;
) are solid acid catalyst particles, (5) Fi low temperature oxidation catalyst particles (
3), solid acid catalyst particles (4), and fluorinated graphite particles (6) are dispersed and cured.

Composition Example 1 using the sound absorbing material of this invention. Various performances were investigated while comparing with a porous metal material that was not coated with the composition at all.

FIG. 2 shows the weight change rate due to corrosion when the material was left in air containing 5 ppm of sulfur dioxide (sulfur dioxide gas) for 72 hours at a temperature of 400 to 800 DEG C. using an electric furnace. Curve a shows the weight change rate of the sound absorbing material of the present invention manufactured as described above, and the curve a shows the weight change rate of the sound absorbing material made of only a metal porous body using the same material. As is clear from FIG. 2, the sound absorbing material of the present invention has an exhaust gas temperature of 400 to 800, which is the exhaust gas temperature in an exhaust silencer for an internal combustion engine.
Celsius, and even in air containing sulfur dioxide, corrosion hardly progresses and it has good corrosion resistance. In comparison, conventional metal porous materials suffer from severe weight changes due to corrosion as the temperature rises.
Visual observation revealed that greenish corrosion products were attached to the surface.

FIG. 8 shows the catechism direct incidence sound absorption coefficient measured under the same conditions using the in-pipe method (JIS A 1405) K.

Curve C is the characteristic of the sound absorbing material of the present invention, a sound absorbing material made only of curved dti metal porous bodies. From Figure 88, it can be seen that the sound absorbing material of the present invention has a significantly higher sound absorption coefficient than that of a material made only of porous metal.

This is composition example 1 from the surface of the metal porous body. The composition shown in FIG. 1(B) obtained by coating and curing the composition is essentially porous, so air can flow through the interior of the chamber.

That is, the coated cured product of Composition Example 1.0 itself forms part of the sound absorber9, and the sound absorption coefficient can be adjusted depending on the method of coating.

Next, 1. The above two types of sound absorbing materials were molded into a cylindrical shape and pressed as shown in Fig. 4 to form an exhaust silencer t-S, which was installed in a commercially available domestic passenger car (#IP air volume 1,400 cc). After approximately 10,000 km of actual driving, the silencing performance was measured according to JIS D 161g, and compared with the initial value before actual driving. 91
In Figure 54, traces indicate the casing constituting the exhaust silencer, -
is the exhaust gas inlet pipe, the ring is the exhaust gas passage, and! ! 41Fi
Sound absorbing material, - is the exhaust gas outlet pipe. Figure 5 shows the frequency characteristics of the silencing performance. Curves et and es Fi are ID shi, curves fl and f!, respectively, at the initial stage and after actual running when using the sound absorbing material of this invention. are the characteristics at the initial stage and after actual running when using a conventional sound absorbing material consisting only of porous metal and steel materials. As can be seen from Figure 5, the sound absorbing material of this invention not only has good initial silencing performance, but even after 10,000 km of actual driving, the initial performance of #1 has not deteriorated. On the other hand, in the case where only the sound absorbing material was made of porous gold and steel material, the silencing performance decreased significantly in all measurement frequency bands after 10,000 km of actual running. In addition, when both sound absorbing materials were taken out and visually observed after measuring their silencing performance, it was found that the sound absorbing material of this invention was almost #1 clean like the initial one, but the sound absorbing material of the present invention was clean as #1, but the sound absorbing material of only the metal porous material was completely clean. A large amount of black tar-like and soot-like combustion residue and yellow-green corrosion products adhere to the tank, causing severe clogging. As can be seen from these results, the low-temperature oxidation catalyst and solid acid catalyst dispersed in the sound absorbing material Fi sound absorbing material of Jin's invention are
℃, maximum 800℃) K activates it and exerts a catalytic action, so if the component that becomes tar in the exhaust gas (1 ml of incineration residue) adheres to it, the temperature is such that it will completely burn away. In addition to automatically oxidizing and decomposing (surface combustion) to purify and remove the carbon dioxide at low temperatures, that is, at exhaust gas temperatures, the atomized graphite mixed in with the catalyst also has a soot adhesion prevention function and soot. It is thought that the adhesion and decomposition function was fully demonstrated, which is why the initial sound-dampening performance was maintained. In this case, the solid acid catalyst prevents the tar-forming component from being oxidatively polymerized (polymerized), reduces the molecular weight of the component, and makes it easier to vaporize [7], and the low-temperature oxidation catalyst prevents the oxidative decomposition of this component. ! - Play a role of helping. A solid acid catalyst is a substance that has the function of releasing protons (H+) or accepting pairs of electrons.The above-mentioned catalytic function is used in the petrochemical industry to contact heavy oil with a high boiling point (high temperature vaporized substance). Decomposes to a low boiling point (low temperature oxidation catalyst)
This is a well-known function known as cranking, which converts oil into lighter oil. In this invention, this function is combined with a low-temperature oxidation catalyst and further utilizes humidified graphite.
At 0 to 600°C, the solid acid catalyst performs well in the above-mentioned functional tubes, so we found that the low-temperature oxidation catalyst also works better, and we also added fluorinated graphite, which can effectively perform the low*area energy tubes. This is one of the basics of this invention.

The above-mentioned buttomized graphite and other components can effectively exhibit their respective functions at 5 to 96% by weight, but it is preferable that #'' is 50% by weight.

[Example 2. ] Powder sintered metal
and 8. As in Example 1, each of the mixtures was applied onto the sintered metal by IfCall & spray, and then cured by firing to obtain the sound absorbing material of the present invention.

(Composition Example 2.) Low-temperature oxidation catalyst: Manganese dioxide 2511% Four-experience catalyst: Natural zeolite) 22flE% Binder: Methylphenyl silicone 201t% Additive: Alumina, (Composition 8.) Low-temperature oxidation catalyst: Dioxide Nickel 14fi% Cobalt oxide 711% Solid acid catalyst Nisilica magnesia 12f1% Silica silconi 1 811% Binding agent: Sodium silicate 12fi% Calcicum phos 7ate 811% With this sound absorbing material and the above m- porous metal body, composition example 2
．． Also, Example 1. In exactly the same way as in the case of tsiv
Beta. As a result, composition example 2. and 8. The sound absorbing material of the present invention coated and cured with the composition has corrosion resistance, sound absorption coefficient,
Also, in both cases of changes in noise reduction performance over time due to prevention of clogging during actual vehicle driving, Example 1.0 No. 2
It was found that the characteristics were almost as good as those shown in FIGS. 8, 8, and 5.

By the way, as the low-temperature oxidation catalyst used in this invention, composition example 1. ~8. In addition to those mentioned above, 1Cry's
, Ai, 0, metal oxides such as ZnO, PbO, and NiC
r104, Mn Crt04, Cu Clo4, MnF
e! Composite metal oxides such as 04 and Pt%Pd%Rh
%Ru.

Powders and fine particles of noble metals such as Ag, which have oxidation catalytic activity and are heat resistant, can be used.
Of course, two or more of these may be used in combination.

The solid acid catalyst used in this invention has compositions 1 to 8.
．． In addition to the Amano listed above, there are 1-activated alumina, silica alumina, panadicum pentoxide, alumina boria, rubite, synthetic zeolite, acid clay, etc.

The fluorinated graphite used in this invention is a chemically very stable white to gray fine powder in which one fluorine atom is strongly bonded to each carbon atom through a covalent bond. It is produced by directly reacting fluorine generated (by electrolysis of industrial Ktl butoxylic anhydride) with carbon. Its properties include low surface energy and a small coefficient of friction, so it has been put into practical use as a solid lubricant. In this invention, the most suitable method for dispersing and adhering the fluorinated graphite to the surface of a porous material is to apply and bake it dispersed in a resin binder or an inorganic binder, as described in the Examples. When a metal is used as a porous material according to the present invention, heat-resistant materials such as Ni and Cr are dispersed in a plating solution, and graphite nonathanide is eutectoid plated on the surface of the metal porous body. The method was also effective. It is also effective to use commercially available spray sets and varnishes in which fluorinated graphite is dispersed in a resin binder.

In addition, as the metal porous body used as the base material in this invention, commercially available general-purpose materials such as metal fibers and inorganic fiber reinforced metals can be used in addition to foamed metals and sintered gold steel O as in the examples. can. And when it comes to materials, in addition to Nl and gunmetal, there are also AI, Fe-Cr, Fe-Ni-
Alloy materials such as Cr, Fe-Cr-AI, etc. can also be used.

The heat-resistant binders used in this invention include harou (vitreous frits), alkali metal silicates, colloidal alumina, metal phosphates,
Examples include cements, silicone resins (varnishes), and mixtures thereof.

The sound-absorbing material of the present invention is intended to be used in an exhaust silencing device for an internal combustion engine, but depending on how it is used, it may also be used as a sound-absorbing material in other combustion equipment.

As explained above, the sound absorbing material of the present invention in which a heat-resistant binder containing a low-temperature oxidation catalyst, a solid acid catalyst, and further K fluorinated graphite is applied and hardened to a porous metal substrate is suitable. It has sound absorption performance, excellent high humidity oxidation resistance and corrosion resistance,
And when used as a sound absorbing material for an exhaust silencer for an internal combustion engine, it can effectively prevent tar and soot adhesion and also
It is possible to prevent the deterioration of the silencing performance caused by knots and maintain the good silencing performance at the beginning. Therefore, because of its high performance and long life, it can be widely used in exhaust muffling devices for internal combustion engines such as automobiles.

[Brief explanation of drawings]

Figures 1 (A) and (B) are enlarged views showing the structure of the metal porous body and the sound absorbing material of the present invention, respectively, Figures 2, 8, and 6 [i] Characteristics showing the performance of the sound absorbing material of the present invention. Figure, 4th
The figure is a sectional view showing an application example of the sound absorbing material of the present invention. In the figure, the same reference numerals indicate the same or corresponding parts, (1) is the skeleton of the metal porous body, (2) is the pore, (a) IT low temperature oxidation catalyst particles, (4) Fi solid acid catalyst particles, (5) ) is a heat-resistant binder, and (6) is a buttomized graphite. Agent S Shu Xin - (1 other person)

Claims (1)

[Claims] A sound-absorbing material characterized in that a heat-resistant binder containing a low-temperature oxidation catalyst, a solid acid catalyst, and graphite fluoride is applied and hardened to a porous metal body.