JPS6316116A - Exhaust device for multicylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress the thermal stress by reducing the temperature difference of an exhaust collecting chamber by connecting a plurality of exhaust pipes with the exhaust collecting chamber at the inlet of a catalytic container and installing the exhaust pipes so that the exhaust gas is sprayed onto the side walls of the exhaust collecting chamber. CONSTITUTION:An exhaust collecting chamber 11 is connected with the inlet side of a catalytic container 1 in which a catalyst 4 is accommodated. Exhaust pipes 15a-15d are connected with the front surface walls 13b and13c and side walls 13a and 13d of the collecting chamber 11. In this case, the exhaust pipes 15a and 15d connected with the both side walls 13a and 13d are installed towards the side walls on the opposite side and the edge surface of the catalyst close to the side walls. Further, the exhaust pipes 15b and 15d connected with the front surface walls 13b and 13c are installed towards the edge surfaces of the center part of the catalyst 4. Therefore, the temperature difference of the whole exhaust collecting chamber is reduced by directly spraying a portion of the exhaust gas onto the side walls, and the thermal stress can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a catalyzed gas manifold for internal combustion engines having three or more cylinders.

(Prior Art) Conventionally, a method in which a plurality of exhaust pipes are assembled at the entrance of a catalyst container is disclosed in Japanese Unexamined Patent Publication No. 134211/1983 (a) and Japanese Utility Model Application No. 56/1983.
It is known from No. 129513(b) etc. Of these, (a) has 211 exhaust pipes arranged in a V-shape with respect to the end face of the catalyst, with their center lines intersecting in front of the catalyst, and (b), The exhaust gas exiting from each exhaust pipe of the exhaust manifold collides with different positions on the end face of the catalyst.

(Problems to be Solved by the Invention) In the present invention, the exhaust manifold is made of a gathering chamber formed from a thin material by forming, such as a thin stainless steel tube and a stainless steel root by deep drawing, instead of the conventional one made of cast iron. Engine f by making the exhaust manifold lighter
Although the purpose is to reduce f1fd, when such a material is used, there is a problem in that large thermal stress is likely to occur if there is a local temperature difference in the gathering chamber because the coefficient of expansion is large. When there are two exhaust pipes connected to the collecting chamber as in the conventional example (a), it is easy to equalize the temperature of the collecting room and distribute the exhaust gas to the catalyst evenly. If there are three or more exhaust pipes, the inner exhaust pipes are shorter and less likely to be cooled by the outside air, resulting in a high temperature at the cervical canal connection and a temperature difference between the outer exhaust pipe and the connecting side wall. This may cause thermal stress, and stress may be added due to the difference in elongation of each exhaust pipe.

On the other hand, although the conventional example (b) can evenly distribute the exhaust gas emitted from the four exhaust pipes to the catalyst, it does not take into account the occurrence of temperature differences in the manifold.

(Means for Solving the Problems) The present invention prevents the occurrence of thermal stress and equalizes the distribution of exhaust gas to the catalyst. An exhaust gas collection chamber connected to the inlet side of the catalyst container and bulging toward the exhaust pipe side, and three or more exhaust pipes connected to the front wall and both side walls of the exhaust gas collection chamber are respectively connected by welding to form an exhaust gas collection chamber. The exhaust pipes connected to both side walls of the catalyst are oriented toward the opposite side walls and the end face of the catalyst near the side walls, and the exhaust pipes connected to the front wall are oriented toward the end face of the central portion of the catalyst.

(Function) With the above configuration, a considerable amount of the exhaust gas that flows into the exhaust gas collection chamber from each of the outer exhaust pipes directly collides with the opposite side walls, thereby heating both walls and causing a collision with the front wall. It reduces the temperature difference to prevent the generation of thermal stress, and creates a swirling flow along the side wall to equalize the flow of exhaust gas in the exhaust gas collection chamber.

(Example) Hereinafter, an example of the present invention implemented in an in-line four-cylinder engine will be described with reference to the drawings.

In FIGS. 1 and 2, E is an engine, (1) is a catalyst container, and the catalyst container (1) is equipped with an oval honeycomb catalyst (4) through gaskets (5) and (6). The peripheral edges (9) of the flanges (7) and (8) are welded together, and a connecting flange ([) is welded to the downstream side.

An exhaust gas merging chamber (+1) is welded to the upstream side of the catalyst container (1). The merging chamber 11'D is formed by deep drawing, bulges from the flange 0b toward the exhaust pipe, and has four planar walls (13a), (13b), (13c), and (13d).
) are formed, and (13a) and (13d) each face to the side, and (13b) and (13C) both face to the front, although there is a slight inclination.

Openings with projecting edges (14a HI3 d ) are provided in the side walls (13a) (13d) by burring, and ordinary openings are provided in the front walls (13b) (13c). And each opening has an exhaust pipe (Is a H2S
b) (15c) The downstream side of (Is d) is inserted and welded.

The upstream part of each exhaust pipe is inserted and welded into the opening provided in one flange ○e, and the flange stopper has a hole a'h (+71...) for fixing it to the cylinder head. ,
Holes ('191'le...) for weight reduction, notches (19, etc.) for absorbing thermal deformation are provided.

These catalyst container (1), exhaust gas collection VAT, exhaust pipe (1)
5a) to (Is d) and flange 0G'8 are:
Ferritic 5uS409L with a small expansion coefficient is used as the stainless steel, and 5IIS430 is used as the welding rod.
L is used.

Of the exhaust pipes, the exhaust pipe (1jt+) (15c) that connects to the front wall (13bH13C) has a gentle two-dimensional curve;
The exhaust pipe (13a) (13dl) connected to
After rising from the flange plate ae, it curves once, and on the downstream side, it curves a second time diagonally sideways when viewed from the direction of curvature, enters the frontage of both side walls (13a) (13d), and forms a ridge (14a HI3 d). 2 welded.

Each exhaust pipe (Isa) to (15dl is curved to facilitate deflection during thermal expansion, and the base wall (13a) to (15dl)
Since the side wall (13d) has a planar shape, it can easily bend against the force acting perpendicularly to the wall surface, and the side wall (13a)
) (13d) can prevent stress from concentrating on the welded portion when the exhaust pipe (15bE5c) is deformed to tilt with respect to the side wall.

In the figure, ■ indicates the 02 sensor mounting hole, ■ indicates the cover mounting screw, and ■ indicates the exhaust temperature meter mounting hole.

The center line of each exhaust pipe is located at a point a on the end surface of the catalyst (4).
The projected figure of the frontage of each exhaust pipe with respect to a plane that intersects at points b, c, and d and coincides with the end face is as shown in FIG. 3.

In the figure, A, B, C and D are exhaust pipes (15
a) (Is bH15c) (There is a projection view of 15dl.

Therefore, almost all of the exhaust gas coming out from the intermediate exhaust pipe (15b Hls c ) is blown onto the catalyst end face, but nearly half of the exhaust gas coming out from the exhaust pipes (ISa) (ISdl) at both ends is blown onto the side walls (13a) (13d). Sprayed directly.

The inner exhaust pipe (
15b) (15C) is short and outer exhaust pipe (15a)
(15d) is long, so the outer exhaust pipe receives more cooling action from the outside air than the inner exhaust pipe and is therefore lower in temperature.
The side walls (13a) (13d) of the gathering room ('Iv) also have a smaller amount of heat transfer than the front wall (13C) (13d) and a smaller temperature rise.This temperature difference causes thermal stress in the heat of the gathering room at+, Furthermore, due to the difference in elongation due to the temperature difference between each exhaust pipe, different amounts of stress are applied to the collective room (
Added to 1. Stainless steel has a large coefficient of expansion, so these stresses tend to increase, but in the present invention, exhaust pipes (
Since nearly half of the exhaust gas coming out of Isa) (15d) is blown directly, the heating by this exhaust gas is added to the heat transfer from the exhaust pipe, and the temperature difference across the walls of the collecting room (11) is reduced. At the same time, the thermal stress is reduced, and at the same time, this exhaust gas swirls and flows along the wall of the exhaust gas collection chamber a'D'5, causing a swirling flow in the exhaust gas remaining in the exhaust gas collection chamber, resulting in an even distribution of exhaust gas to the catalyst. oxidation and equalization of the catalyst temperature.

(Effects of the Invention) As described above, the present invention blows a part of the exhaust gas directly onto the side wall to reduce the temperature difference in the entire exhaust gas collection chamber.
Since thermal stress can be suppressed to a small extent, it is possible to use thin stainless steel materials, and the weight M can be reduced compared to conventional cast iron materials, which is extremely effective in improving fuel efficiency when used in automobiles. It is. Furthermore, the exhaust gas blown against the side wall flows along the inner surface of the side wall, which creates a swirling flow within the exhaust gas collection chamber, equalizing the distribution of exhaust gas to the catalyst and equalizing the catalyst temperature, resulting in effective exhaust purification. It is carried out in a regular manner.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a side view showing the state in which it is attached to an engine, FIG. 2 is a front view, and FIG. 3 is a projection view of the exhaust pipe relative to the end face of the catalyst. (1)...Catalyst container (4)...Catalyst av
...Exhaust collective room (13a) (13d l...Side wall (13C) (13d) ...Front wall (15
a) to (15d), Exhaust pipe. 2 people outside Figure 2

Claims (1)

[Claims] A catalyst container containing a catalyst, an exhaust gas collection chamber connected to the inlet side of the catalyst container and bulging toward the exhaust pipe side, and three or more exhaust pipes connected to the front wall and both side walls of the exhaust gas collection chamber. The exhaust pipes are connected by welding, and the exhaust pipes connected to both side walls of the exhaust gas collecting chamber are oriented toward the opposite side wall and the end face of the catalyst near the side wall, and the exhaust pipe connected to the front wall is oriented towards the end face of the central part of the catalyst. An exhaust system for a multi-cylinder internal combustion engine.