JP2816991B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine.

[Conventional technology]

In internal combustion engines mounted on automobiles, etc., a catalyst body with a catalyst attached to a ceramic honeycomb carrier is attached to the exhaust manifold connected to the exhaust port of the internal combustion engine, and the exhaust gas passes between the catalyst bodies to oxidize. To purify unburned components in the exhaust gas. In the case of a small internal combustion engine mounted on a motorcycle or the like, a catalyst body made of a cloth body made of glass wool or the like with a catalyst agent attached to the inner surface of an exhaust pipe connected to the exhaust port of the internal combustion engine, and a holding piece is used. The presser and the exhaust gas are brought into contact with the catalyst to purify unburned components. For example, JP-B-59-1324, JP-A-61-96
See No. 120 publication.

[Problems to be solved by the invention]

Since the exhaust gas passes through a large number of honeycomb-shaped small holes in the honeycomb-shaped catalyst, the flow path area is reduced, the resistance is large, and the output of the engine is reduced. In particular, in a small engine, the performance is greatly affected by a decrease in output. Further, there is a disadvantage that the exhaust manifold becomes large and heavy. In the case where a cloth-like catalyst body is stretched on the exhaust pipe, it is troublesome and costly to stretch the catalyst body, and there is a problem in heat resistance and durability.

In view of the foregoing, the present invention provides an inner pipe having a large number of ventilation holes provided inside the exhaust pipe with a gap provided, a catalyst attached to the inner pipe, and exhaust gas applied to the catalyst with low resistance to purify the exhaust gas. It is an object of the present invention to provide an exhaust gas purifying apparatus for an internal combustion engine which can be manufactured easily, inexpensively and lightweight, and has good adhesion and high durability.

[Means for solving the problem]

In order to achieve the above object, an exhaust gas purifying apparatus for an internal combustion engine according to the present invention is arranged such that an internal pipe is attached at an interval in an exhaust pipe connected to an exhaust port of the internal combustion engine, and the exhaust pipe and the internal pipe are made of a steel plate or Using a stainless steel plate, separate the left and right molded parts and combine them, and attach the inner pipe's mating edge to the exhaust pipe's mating edge by welding and attaching together,
The inner tube has a large number of ventilation holes, and forms an intermediate film by coating a catalyst such as non-toxic alumina on the inner and outer surfaces of the inner tube by an aluminizing method or the like,
A metal oxide such as alumina is sprayed on the surface of the intermediate film to form a carrier layer having a large number of holes, and the carrier layer is immersed in a catalyst solution to impregnate the carrier layer with the catalyst solution, and then dried. By firing, the catalyst particles are firmly attached to the carrier layer, and the exhaust gas flowing through the exhaust pipe is applied to the catalyst to purify the catalyst.

(Operation)

The inner pipe attached to the exhaust pipe has a large number of ventilation holes and a gap between the inner pipe and the inner surface of the exhaust pipe. Easy to hit catalyst. The intermediate coating covering the surface of the inner tube is non-toxic to the catalyst, preventing the catalyst from directly hitting the inner tube,
It is possible to prevent the catalyst from causing a chemical reaction and to elute metal ions, thereby improving durability. Since the carrier layer provided on the intermediate film is formed by spraying a metal oxide, a large number of pores are formed and the adhesion of the catalyst solution is improved. Further, the carrier layer can relieve thermal strain due to thermal shock or thermal cycle by the intermediate film, and can firmly adhere. Then, the exhaust gas flowing through the exhaust pipe is applied to the catalyst in the inner pipe to cause an oxidation reaction, thereby purifying unburned components in the exhaust gas.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

An exhaust pipe 3 is connected to an exhaust port 2 of the internal combustion engine 1. Inside the exhaust pipe 3, an inner pipe 5 in which a number of ventilation holes 4 are formed by punching is provided with a gap 6 therebetween. Exhaust pipe 3
And the inner tube 5 are formed by using a steel plate or a stainless steel plate and divided into right and left, and are welded together.
The fitting edge of the inner pipe 5 is sandwiched between the fitting edges of the exhaust pipe 3 so as to be integrally welded and attached. As shown in FIG. 2, the catalyst is coated with a non-toxic metal such as aluminum on the inner and outer surfaces of the inner tube 5 by an aluminizing method or the like to form an intermediate film 7. Then, as shown in FIG. 3, a metal oxide such as alumina is sprayed on the surface of the intermediate film 7 to form a carrier layer 8 having many holes. Then
As shown in FIG. 4, the carrier layer 8 is immersed in the catalyst solution 9 to impregnate the carrier layer 8 with the catalyst solution 9. When this is dried and calcined, as shown in FIG.
Grains adhere. The intermediate film 7 can prevent the catalyst 10 from coming into contact with the inner tube 5 and the like, thereby preventing a chemical reaction and elution of metal ions, thereby increasing the durability. Further, the intermediate film 7 relieves thermal strain due to thermal shock or thermal cycle, keeps the carrier layer 8 in a firmly adhered state, and prevents peeling. The intermediate film 7 has a coefficient of thermal expansion between the inner tube 5 and the carrier layer 8. Similarly, an intermediate film 7 and a carrier layer 8 may be formed on the inner surface of the exhaust pipe 3 so that the particles of the catalyst 10 are fixed.

The exhaust gas flowing in the exhaust pipe 3 hits the catalyst 10 of the inner pipe 5 and causes an oxidation reaction to purify unburned components in the exhaust gas. An expansion chamber 11 is connected to the rear end of the exhaust pipe 3.
Further, a muffler 12 is connected to the expansion chamber 11, the exhaust gas is silenced by the muffler 12, and is discharged from the rear end of the muffler 12.

〔The invention's effect〕

As described above, since the present invention is configured as described above, the exhaust gas can be applied to the catalyst of the inner pipe provided with the ventilation hole to purify the catalyst, the resistance to the exhaust gas flowing is small,
Output can be reduced little. Also, by the intermediate film,
The catalyst can be prevented from deteriorating, and the carrier layer can be prevented from peeling off, and can be firmly adhered and durable. And
The inner tube is easy to install, inexpensive and lightweight.

[Brief description of the drawings]

Fig. 1 shows an embodiment of the present invention. Fig. 1 is a cross-sectional view of an exhaust pipe, Fig. 2 is a partial cross-sectional view in which an intermediate coating is applied to an inner pipe, and Fig. 3 is a part in which a carrier layer is provided in the inner pipe. Sectional view, FIG. 4 is a partially enlarged sectional view of impregnating the carrier layer with the catalyst solution, FIG. 5 is a partially enlarged sectional view of the state where the catalyst is calcined in the carrier layer, and FIG. 6 is a partial longitudinal section of the exhaust pipe. FIG. 7 is an overall side view. 1 ... internal combustion engine, 2 ... exhaust port, 3 ... exhaust pipe, 4 ...
Vent hole, 5: inner tube, 6: gap, 7: intermediate film, 8
... Carrier layer, 9 ... catalyst solution, 10 ... catalyst.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 3/24 F01N 3/28 301

Claims (1)

(57) [Claims] An inner pipe is attached with a space provided in an exhaust pipe connected to an exhaust port of an internal combustion engine, and the exhaust pipe and the inner pipe are formed by using a steel plate or a stainless steel plate so as to be divided into left and right parts, and The inner pipe is sandwiched between the mating edges of the exhaust pipe and is integrally welded and attached. The inner pipe has a large number of ventilation holes, and a catalyst is provided on the inner and outer surfaces of the inner pipe. Non-toxic metal such as alumina is coated by aluminizing method to form an intermediate film,
A metal oxide such as alumina is sprayed on the surface of the intermediate film to form a carrier layer having a large number of holes, and the carrier layer is immersed in a catalyst solution to impregnate the carrier layer with the catalyst solution, and then dried. An exhaust gas purifying apparatus for an internal combustion engine, characterized in that catalyst particles are firmly attached to a carrier layer by firing, and exhaust gas flowing in an exhaust pipe is applied to a catalyst to purify the exhaust gas.