JPH08135439A - Catalyst installation structure of exhaust device for vehicle - Google Patents

Abstract

PURPOSE: To improve installation strength of a catalyst to an exhaust device by dividing an exhaust pipe into left and right ones or into front and rear ones and connecting both of divided bodies by way of sandwiching the catalyst between the divided bodies. CONSTITUTION: An exhaust device 1 for a small displacement two-cycle engine is furnished with an exhaust pipe 2 connected to an exhaust port of the engine and a muffler 3, and a silencer is connected to a rear end tail part 3a. Thereafter, first and second catalysts 5, 6 are installed in the exhaust pipe 2 and the muffler 3. This exhaust device 1 is constituted by welding and connecting left and right divided bodies 2a, 2b by connection flanges 12a, 12b and sandwiching and fixing the first catalyst 5 by support brackets 8a, 9a and 8b, 9b welded and fixed on inner surfaces of the left and right divided bodies 2a, 2b. The maffler 3 is constituted in the same way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting a catalyst used in a vehicle exhaust system to the exhaust system, and more particularly to a mounting system for mounting the catalyst to the exhaust system to improve workability and strength. Regarding the improvement of the structure.

[0002]

2. Description of the Related Art For example, some catalysts used in an exhaust system of a motorcycle have a metal pipe of stainless steel or the like on which an outer surface is loaded with a slurry containing a precious metal powder. Conventionally, as a structure for attaching such a catalyst to a vehicle exhaust device (exhaust pipe), the exhaust pipe is divided into two parts in the axial direction, left and right, and a bracket is provided on the inner peripheral surface of one of the divided bodies. There is a method of welding and fixing the above catalyst.

[0003]

However, in the above-described conventional method of welding and fixing, since the metal pipe is welded while the slurry adheres to the outer surface, the weld strength of the metal pipe is low. There is. In order to avoid this problem of strength reduction, it is necessary to scrape off the slurry adhering to the welded part of the metal pipe,
The number of steps is increased by that amount, which causes a problem of cost increase.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a catalyst mounting structure for a vehicle exhaust system which can improve the mounting strength of the catalyst to the exhaust system.

[0005]

According to a first aspect of the present invention, in a catalyst mounting structure for a vehicle exhaust system in which a catalyst is arranged and fixed in an exhaust pipe, the exhaust pipe is divided into left, right or front and rear parts,
It is characterized in that a catalyst is sandwiched between the two divided bodies and the two divided bodies are joined together.

According to a second aspect of the present invention, there is provided a catalyst mounting structure for a vehicle exhaust system in which a catalyst made by supporting a slurry containing a noble metal powder on a cylindrical metal carrier is welded and fixed in an exhaust pipe. It is characterized in that the above-mentioned slurry is carried in a state where masking is applied to a portion to be welded on the outer surface of the carrier, and a non-supported portion of the slurry due to the masking of the carrier is welded.
Further, the invention of claim 3 is characterized in that the slurry is not carried also on the inner surface corresponding to the welded portion.

[0007]

According to the catalyst mounting structure of the exhaust system for a vehicle of the first aspect of the invention, the exhaust pipe is divided into left, right or front and rear, and the catalyst is sandwiched between the two divided bodies. The catalyst can be fixed without using a welding means such as the conventional structure, the attachment strength can be prevented from being deteriorated by welding the slurry adhering portion, and the deterioration of the catalyst due to the welding can be avoided.

According to the catalyst mounting structure of the exhaust system for a vehicle of the second aspect of the invention, the catalyst is used in which the slurry is carried in a state where the welded portion of the carrier is masked, and the carrier is loaded with the slurry. Since the unwelded portion is welded, it is possible to avoid a reduction in the attachment strength due to the welding of the slurry adhering portion. Further, in the invention of claim 3, alteration of the slurry on the inner surface of the welded portion is avoided.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 are views for explaining a catalyst mounting structure of a vehicle exhaust system of a first embodiment according to the invention of claim 1, FIG. 1 is a schematic side view of the exhaust system, and FIG. FIG. 3 is a schematic sectional plan view of the exhaust device, FIG. 3 is an enlarged view of a main part of FIG. 2, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is a sectional view showing a modification of FIG.

In the figure, reference numeral 1 shows an exhaust system for a small displacement two-cycle engine. The exhaust system 1 includes an exhaust pipe 2 connected to an exhaust port of an engine, a muffler 3 welded to the exhaust pipe 2, and a silencer 4 bolted to a rear end tail portion 3a of the muffler 3, The muffler 3 is attached to the vehicle body side by a mounting bracket 3b. Then, inside the exhaust pipe 2 and the muffler 3, the first and second catalysts 5 and 6 are mounted by a mounting structure described later. In addition, the exhaust gas from the engine is the first and second catalysts 5,
While being purified by 6, the muffler 3 and the silencer 4 mute the sound, and then it is discharged to the outside.

The first catalyst 5 is made of ferritic stainless steel or the like, and a carrier 7 made of a metal pipe having a large number of punching holes 7a is dipped in a mixed liquid (i) in which alumina oxide powder is made into a muddy state, It is formed by immersing in a mixed solution (b) of a noble metal powder such as platinum, rhodium or palladium, which serves as a catalyst, and an acid, and then heating and drying at a high temperature of about 500 ° C. The second catalyst 6 is formed by sequentially immersing the honeycomb-shaped carrier 6a made of a heat-resistant alloy or the like in the mixed liquids i and b and heating and drying. The above-mentioned mixtures a and b are generally called a slurry by combining the two. Further, the mixture (a) is for increasing the supported surface area and for preventing the noble metal from peeling off.

The exhaust pipe 2 is constructed by welding the left and right split bodies 2a and 2b together with joint flanges 12a and 12b. Support brackets 8a, 9a and 8b, 9b are welded and fixed to the inner surfaces of the left and right split bodies 2a, 2b, and the first and second support brackets 8a, 9a and 8b, 9b are used to fix the first bracket. The catalyst 5 is clamped and fixed. The reference numeral 7b is a locking recess for preventing the first catalyst 5 from being axially displaced from the holding position.

The muffler 3 is a left and right divided body 3
It has a structure in which a and 3b are welded to each other by the coupling flanges 12a and 12b. The left and right support brackets 10 are provided on the inner surfaces of the left and right divided bodies 3a and 3b.
a, 11a and 10b, 11b are fixed by welding,
These support brackets 10a, 11a and 10b, 1
The second catalyst 6 is clamped and fixed by 1b.

Next, the function and effect of the catalyst mounting structure of this embodiment will be described. To mount the first and second catalysts 5 and 6 in the exhaust device, the support brackets 8a, 8b and 9a are provided on the inner surfaces of the left and right split bodies 2a, 2b and 3a, 3b of the exhaust pipe 2 and the muffler 3. , 9b, 10a, 10
b, 11a, 11b are fixed by welding, the first catalyst 5 is sandwiched between the support brackets 8a, 9a and 8b, 9b, and the second catalyst 6 is sandwiched between the support brackets 10a, 11a and 10b, 11b. The left and right split bodies 2a,
2b, 3a and 3b are welded and joined by connecting flanges 12a and 12b. As a result, the first and second catalysts 5 and 6 are fixed in the exhaust pipe 2 and the muffler 3.

As described above, in the catalyst mounting structure according to this embodiment, the first catalyst 5 is clamped and fixed in the exhaust pipe 2 by the support brackets 8a, 8b, 9a, 9b, and the second catalyst 6 is fixed in the muffler 3. Support brackets 10a, 10
Since they are sandwiched and fixed by b, 11a, and 11b, when the catalyst is welded to a bracket or the like as in the above-mentioned conventional example, it is possible to avoid deterioration of the catalyst and reduction in mounting strength due to welding.

In the above embodiment, as shown in FIG. 4, the support brackets 8a and 8b have a shape facing each other in the exhaust gas flow direction, but the support brackets 8a and 8b are shown in FIG. As shown, it may be formed in a shape along the flow direction of the exhaust gas. This makes it possible to avoid an increase in exhaust resistance.

Here, in the above-mentioned embodiment, the catalyst is sandwiched and fixed by the support brackets, thereby avoiding the deterioration of the catalyst and the reduction of the mounting strength due to the welding as in the above-mentioned conventional example. Welding of the support bracket to the non-slurry supporting portion avoids a decrease in mounting strength. Next, a catalyst mounting structure according to a second embodiment of the present invention will be described with reference to FIG. . FIG. 6 is a schematic view showing an example of a masking method in the above slurry carrying work, and the same reference numerals as those in FIGS. 1 to 5 show the same or corresponding portions.

In FIG. 6, a cap 13 made of an elastic material such as rubber is fitted to the left end of the metal pipe carrier 7, and the outer and inner surfaces of the left end of the carrier 7 are masked by the cap 13. There is. A ring 17 made of an elastic material such as rubber is fitted on the outer surface of the central portion of the carrier 7, and the outer surface of the central portion is masked by the ring 17. Furthermore, in the center of the carrier 7, a tubular body 14 made of an elastic body such as a tubular rubber is arranged. The left end portion of the tubular body 14 in the drawing is sealed by a cap 15 and the right end portion thereof is closed. A pipe 16 is attached to the. Air is blown from the pipe 16 into the cylindrical body 14 and swells like a balloon in the direction of the arrow in the figure, and is in close contact with the inner surface A of the carrier 7 corresponding to the portion B where the ring 17 contacts. The carrier 7
The inner surface of the center of the is masked.

In the state where the outer and inner surfaces of the left end portion and the central portion of the carrier 7 are masked as described above,
After immersing the carrier 7 in the mixed liquids a and b in this order, the carrier 7 is heated and dried to attach the slurry. Then, when the cap 13, the ring 14 and the cylindrical body 17 are removed, the slurry is not attached to the masked portion and the background of the carrier 7 is exposed. Then, the brackets 8a, 8b, 9a, 9b are welded and fixed to the exposed portions of the background, and the support brackets 8a, 8b, 9a, 9b are sandwiched between the left and right divided bodies 2a, 2b. In addition,
The axial lengths of the masking caps 13, the rings 17 and the cylinders 14 are set so that the non-supported portion of the slurry is equal to or more than the length required for welding and the pitch of the punching holes 7a. Preferably. When sandwiching the support brackets, for example, the right support brackets 8b and 9b are welded and fixed to the right split body 2b as in the first embodiment, and the left support brackets 8a and 9a are split to the left. It may be sandwiched by the body 2a, and by doing so, the mounting strength is further improved.

As described above, in the catalyst mounting structure according to the second embodiment, since the welding portion of the metal pipe carrier 7 is masked, the first catalyst 5 is attached to the support brackets 8a, 8b, 9a and 9b. It is possible to avoid the above-mentioned decrease in welding strength when fixed by welding. Further, in this case, since the slurry is prevented from adhering to the inner surface of the welded portion, the deterioration of the catalyst can be avoided.

In the above embodiment, the rubber ring 17 is attached when masking the outer surface of the central portion of the carrier 7, but a tape-shaped masking member may be attached to the same portion. . The means for supporting the slurry in a masked state can of course be applied to the second catalyst.

In the above embodiment, the exhaust pipe 2 and the muffler 3 are divided into left and right as shown in FIGS. 4 and 5, but the exhaust pipe 2 and the muffler 3 are moved upward and downward. Alternatively, it may be divided in the axial direction.

[0023]

As described above, according to the catalyst mounting structure of the exhaust system for a vehicle according to the invention of claim 1, the exhaust pipe is divided into left, right or front and rear, and the catalyst is sandwiched between the two divided bodies. Since the two divided bodies are connected to each other, there is an effect that it is possible to avoid the deterioration of the catalyst and the reduction of the mounting strength, which are caused when the catalyst is welded to the exhaust device.

According to the catalyst mounting structure of the exhaust system for a vehicle according to the second aspect of the invention, the outer surface of the carrier is welded to the welded portion, and the invention of the third aspect is such that the inner surface corresponding to the welded portion. Since the slurry is carried on the carrier while the portion is masked and the masking portion is welded, even when the catalyst is welded to the exhaust device, avoiding a decrease in mounting strength due to the welding of the catalyst. It is also possible to prevent deterioration of the catalyst.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view of an exhaust system to which a catalyst mounting structure for a vehicle exhaust system according to a first embodiment of the present invention is applied.

FIG. 2 is a schematic plan cross-sectional view of the exhaust device.

FIG. 3 is an enlarged view of a main part of FIG.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view showing a modification of FIG.

FIG. 6 is a schematic view showing an example of a masking method used for a catalyst mounting structure of a vehicle exhaust system according to a second embodiment of the second and third aspects of the invention.

[Explanation of symbols]

2 Exhaust pipe (exhaust pipe) 3 Muffler (exhaust pipe) 2a, 2b, 3a, 3b Split body 5 First catalyst (catalyst) 6 Second catalyst (catalyst) 7 Support 13, 14, 17 Cap, cylinder, ring ( Masking) Lee Ross R

Claims (3)

[Claims] 1. In a catalyst mounting structure for a vehicle exhaust system in which a catalyst is arranged and fixed in an exhaust pipe, the exhaust pipe is divided into left, right, front, and rear, and a catalyst is sandwiched between the two divided bodies to form a catalyst. A catalyst mounting structure for a vehicle exhaust system, characterized in that divided bodies are joined together. 2. A catalyst mounting structure for a vehicle exhaust system, comprising a tubular metal carrier carrying a slurry containing a noble metal powder on which a catalyst is welded and fixed in an exhaust pipe.
The vehicle is characterized in that the slurry is carried in a state where a masked portion is welded on the outer surface of the carrier, and a non-supported portion of the slurry due to the masking of the carrier is welded. Exhaust device catalyst mounting structure. 3. The catalyst for a vehicle exhaust system according to claim 2, wherein the catalyst is carried on the slurry while the masking is also applied to the inner surface corresponding to the welded portion. Mounting structure.