JPH0385316A - Exhaust gas purifying device for internal combustion engine - Google Patents

Abstract

PURPOSE:To oxidize the exhaust gas to be purified by providing an inner tube inside an exhaust pipe of an internal combustion engine, and while adhering the slurry including a catalyst to an irregular layer formed on the inner and outer surfaces of the inner tube, and burning the slurry. CONSTITUTION:An inner tube 5 is provided inside an exhaust pipe 3 of an internal combustion engine with the predetermined space 4. Multiple vent hols 6 are drilled in the inner tube 5. An irregular layer 7 made of metal such as aluminna non-toxic against a catalyst, ceramic and thermet or the like is provided on the inner and outer surfaces of the inner tube 5 by flame coating. The slurry 8 made of catalyst solution and catalyst carrier is adhered to the irregular layer 7 by coating or the like, and thereafter, it is dried to be burned. Consequently, the exhaust gas flowing inside the exhaust pipe 3 contacts the catalyst included in the slurry 8, and the combustible component is oxidized to be purified. A light device having a small exhaust resistance and a line durability can be thereby obtained at a low cost.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an exhaust gas purification device for an internal combustion engine.

(Prior art) In internal combustion engines installed in automobiles, etc., a catalyst body, in which a catalyst is adhered to a ceramic honeycomb-shaped carrier, is attached to the exhaust manifold pipe connected to the exhaust port of the internal combustion engine, and exhaust gas is transferred to the catalyst body. During this period, an oxidation reaction occurs to purify unburned components in the exhaust gas. In addition, in small internal combustion engines installed in motorcycles, etc., a catalyst body with a catalyst agent attached to a substance such as glass wool is stretched on the inner surface of the exhaust pipe that connects to the exhaust port of the internal combustion engine, and is held down with a presser piece. , the exhaust gas is brought into contact with a catalyst body to purify unburned components. For example, Japanese Patent Publication No. 59-1324, Japanese Patent Publication No. 6
See Publication No. 1-96120.

(Problems to be Solved by the Invention) In the honeycomb-shaped catalyst body, exhaust gas passes through a large number of honeycomb-shaped small holes, so the flow path area decreases and there is a lot of resistance.
The output of the engine decreases, and especially in small engines, the impact of the decrease in performance due to the decrease in output is significant. Another disadvantage is that the exhaust manifold becomes large and heavy. Furthermore, the exhaust pipe covered with a cloth-like catalyst is troublesome to install, is expensive, and has problems in heat resistance and durability.

In view of this, the present invention installs an inner pipe having a large number of ventilation holes at intervals inside the exhaust pipe, attaches a carrier carrying a catalyst solution to this inner pipe, and reduces exhaust gas flowing through the exhaust pipe. To provide an exhaust gas purifying device for an internal combustion engine that can be purified by contact with a catalyst, has low exhaust resistance, is inexpensive, lightweight, and has high durability.

(Means for Solving the Problems) In order to achieve the above object, an exhaust gas purification device for an internal combustion engine according to the present invention has an inner pipe installed at a space within the exhaust pipe connected to the exhaust port of the internal combustion engine. , the inner tube is provided with a large number of ventilation holes, the inner and outer surfaces of the inner tube are thermally sprayed with an uneven layer of a non-toxic metal such as alumina or ceramic cermet, and the uneven layer supports a catalyst solution. This is done by applying it by painting, drying it and baking it, and purifying the exhaust gas flowing through the exhaust pipe by hitting the catalyst.

(Function) The inner pipe is provided by punching a large number of ventilation holes and is installed at intervals inside the exhaust pipe, so that exhaust gas can flow in and out through the ventilation holes. The exhaust pipe and inner pipe are made of steel plates or stainless steel plates, and a catalyst cannot be attached to them as they are. On the inner and outer surfaces of the inner tube,
By spraying a non-toxic metal such as alumina, ceramic, cermet, etc. on the catalyst, an uneven layer with fine unevenness is provided on the surface.
A carrier carrying a catalyst solution can be applied, and this can be dried and fired to make it adhere. When the exhaust gas flows through the exhaust pipe, it comes into contact with the catalyst on the surface of the inner pipe, causing an oxidation reaction and purifying unburned components in the exhaust gas.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

An exhaust pipe 3 is connected to an exhaust port 2 of an internal combustion engine 1.

Inside the exhaust pipe 3, an inner pipe 5 is attached with a gap 4 provided therebetween.

The exhaust pipe 3 and the inner pipe 5 are made of steel plates or stainless steel plates, and are molded separately into left and right parts, which are then welded together.The mating edges of the inner pipe 5 are placed between the mating edges of the exhaust pipe 3. It is designed to be attached by sandwiching it between the two and welding it together. A large number of ventilation holes 6 are formed in the inner tube 5 by punching. As shown in FIGS. 2 to 4, the inner and outer surfaces of the inner tube 5 are coated with one or two layers of non-toxic metal such as alumina, ceramic, cermet, etc. as a catalyst, and have fine irregularities on the surface. Layer 7 is provided. Further, the surface of the uneven layer 7 may be formed into a rougher surface by grid blasting or the like. Then, as shown in FIG. 5, a carrier 8 containing a catalyst solution is attached to the uneven layer 7 by painting or the like, and when this is dried and fired, the surface of the uneven layer 7 is coated as shown in FIG. , the carrier 8 containing the catalyst is in close contact. This prevents the catalyst from directly touching the inner tube 5 and prevents the catalyst from being damaged due to toxicity. Furthermore, if a concavo-convex layer is similarly added to the inner surface of the exhaust pipe 3 and the catalyst carrier is brought into close contact with the catalyst carrier, the purification ability can be further improved, and the concavo-convex layer can provide heat insulation, making it easier to maintain the catalyst at the activation temperature. can.

While flowing through the exhaust pipe 3, the exhaust gas contacts the catalyst carrier 8 in the inner pipe 5 to cause an oxidation reaction, thereby purifying unburned components in the exhaust gas.

In addition, a fat expansion chamber 9 is connected to the rear end of the exhaust pipe 3, and a muffler 10 is further connected to the fat expansion chamber 9, and the muffler 10 muffles the sound.
Exhaust gas is released from the rear end of the muffler 10.

(Effects of the Invention) As explained above, since the present invention is configured as described above, a metal such as alumina or ceramic cermet, etc., which is non-toxic to the catalyst, is thermally sprayed on the inner and outer surfaces of the inner pipe installed in the exhaust pipe. By providing the uneven layer, the carrier carrying the catalyst can be brought into close contact with the surface of the uneven layer. Then, the unburned components of the exhaust gas flowing through the exhaust pipe can be purified by the catalyst. The inner pipe can be easily attached to the exhaust pipe, has a simple structure, is lightweight and inexpensive, has high adhesion to the catalyst, is highly durable, has little exhaust resistance, and can be made to have little output drop.

[Brief explanation of drawings]

The figures show one embodiment of the present invention. Fig. 1 is a cross-sectional view of an exhaust pipe, Fig. 2 is a partial cross-sectional view of a state in which the uneven layer is thermally sprayed on the inner pipe, and Fig. 3 is a cross-sectional view of a state where the uneven layer is sprayed on the inner pipe. Fig. 4 is a partially enlarged cross-sectional view of the inner tube with a two-layer uneven layer sprayed on it, Figure 5 is a partially enlarged cross-sectional view of the inner tube with the uneven layer coated with a catalyst carrier. FIG. 6 is an enlarged sectional view after firing, FIG. 7 is a partially vertical side view of the exhaust pipe, and FIG. 8 is a side view of the entire exhaust pipe. 1... Internal combustion engine, 2... Exhaust port, 3... Exhaust pipe,
4... Interval, 5... Inner pipe, 6... Ventilation hole, 7...
- Uneven layer, 8... rough surface.

Claims (1)

[Claims] An inner pipe is installed at intervals within an exhaust pipe connected to an exhaust port of an internal combustion engine, and a large number of ventilation holes are provided in the inner pipe,
A textured layer of non-toxic metal such as alumina or ceramic cermet is provided on the inner and outer surfaces of the inner tube by thermal spraying.
An exhaust gas purification device for an internal combustion engine, characterized in that a carrier carrying a catalyst solution is adhered to the uneven layer by painting or the like, dried and fired, and exhaust gas flowing in an exhaust pipe is purified by hitting the catalyst. .