JPS632567Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas purification device for an internal combustion engine, and particularly to an exhaust gas purification device that has improved durability against heat loads on the exhaust manifold portion.

The exhaust manifold plays the role of collecting exhaust gas from each cylinder and sending it to the exhaust pipe or catalytic converter installed directly below the exhaust manifold, but in counterflow internal combustion engines, it is necessary to avoid interference with the intake manifold. The structure has a curved portion that curves vertically or horizontally. In the part where the passage of the exhaust manifold is curved, the exhaust gas strongly hits the inner wall of the passage on the outer circumferential side of the curve at the part where the mainstream of the exhaust gas collides with the inner wall of the passage, and the amount of heat received from the exhaust gas is large in this part. Therefore, the amount of expansion and contraction of the passage wall is greater than that of other parts. In particular, in the exhaust port section of the exhaust manifold, that is, in the twin pipe section in which a separator as a partition wall is provided inside, a large internal stress is generated in the tube wall due to the difference in thermal strain between the separator and the tube wall. In,
There is a high concentration of internal stress in the pipe wall, and there is a risk that cracks will occur in the pipe wall. In order to prevent this crack from occurring, it may be possible to increase the wall thickness of the separator to suppress thermal deformation of the poteau, but increasing the wall thickness of the separator reduces the cross-sectional area of the branch passage and increases exhaust resistance. At the same time, another problem arises in that the volume of the exhaust manifold increases due to the increase in the volume of the separator, and it has been desired to develop a method for suppressing thermal distortion that does not cause these other problems.

The present invention satisfies these demands, that is, suppresses local thermal distortion of the exhaust manifold without increasing the exhaust resistance and weight of the exhaust manifold, and improves the durability of the exhaust purification device against repeated thermal loads. The purpose is to improve.

The exhaust gas purification device of the present invention, which meets this purpose, has an R-shaped upper and lower part of the collecting port side end of the separator provided in the twin pipe part of the exhaust manifold, so that the main stream of exhaust gas hits particularly strongly. The lower R shape of the separator end portion connected to the lower inner wall surface is made larger than the upper R shape, and the lower R portion of the separator is extended long toward the collecting port portion side.

In this way, by making the lower rounded portion of the separator end portion largely rounded, the temperature difference between the separator and the exhaust port changes more slowly than when the separator is square and connected to the lower wall of the exhaust port. Therefore, in addition to reducing thermal strain, geometrical stress concentration due to the notch effect is also reduced, and local thermal stress concentration is relaxed and reduced. Therefore, even if the heat load is repeated, there is no risk of cracking or the like, and there is no problem in terms of durability.

Preferred embodiments of the exhaust purification device of the present invention will be described below with reference to the drawings.

1 to 4 show an exhaust purification device according to an embodiment of the present invention for a four-cylinder engine. In FIG. 1, 1 is an exhaust manifold, and 2 is an intake manifold, both of which are arranged with their riser portions aligned vertically. The collecting ports extending left and right of the exhaust manifold 1 are collected together in a substantially hemispherical expansion chamber 3 with an enlarged passage cross-sectional area, and a catalytic converter 4 is connected directly below the expansion chamber 3.

As shown in FIGS. 2 and 3, the exhaust manifold 1 has #1 to #4 exhaust ports 5, 6, 7, and 8 connected to #1 to #4 cylinders, and #1 to #4 exhaust ports 5, 6, 7, and 8 are connected to #1 to #4 cylinders. A twin pipe section 9 consisting of two exhaust ports 5 and 6 is connected to one collecting port 10, and a twin pipe section 11 consisting of #3 and #4 exhaust ports 7 and 8 is connected to the other collecting port 12. Double pipe part 9,1
1, as shown in FIG. 4, curves downward and then curves horizontally again to form the collection port
0,12, and collective ports 10,12
As shown in FIGS. 2 and 3, the double pipe portion 9,
The portions 10a, 12a immediately after connecting from 11 are curved toward the expansion chamber 3, and the portions 10b, which continue therefrom,
12b, which extends linearly toward the expansion chamber 3.

The expansion chamber 3 in which the left and right collective ports 10 and 12 open is disposed so as to be biased toward the #1 and #2 exhaust ports 5 and 6 from the center of the exhaust manifold 1 in the left-right direction. Straight section 10 of gathering ports 10, 12
b, 12b passage center line is the expansion chamber 3 in plan view.
Oxygen sensor 1 is installed at this crossing point.
The detection unit 14 is located so that the detection unit 14a of No. 4 is located
A is inserted into the expansion chamber 3 and attached to the wall 13 of the expansion chamber 3.

A riser portion 16 is provided at the center in the left-right direction of the exhaust manifold 1. The riser portion 16 has an opening 15 that opens upward, that is, opens toward the lower surface of the intake manifold 2 attached above.
A heat control valve 17 is provided at a portion of the riser section 16 where the collection port 12 opens into the expansion chamber 3, and is adapted to control the flow of exhaust gas depending on the warm-up state.

The twin pipe parts 9 and 11 have left and right exhaust ports,
Separators 18 and 19 are provided as partition walls to separate #1 exhaust port 5 and #2 exhaust port 6, and #3 exhaust port 7 and #4 exhaust port 8, respectively. The separators 18 and 19 extend from the inlet portions of the #1 to #4 exhaust ports 5, 6, 7, and 8 to the connection portions with the collecting port portions 10 and 12,
The upper and lower ends of the terminal ends of the separators 18 and 19 at the connections between the collective ports 10 and 12 and the exhaust ports are formed into an R shape. Therefore,
The ends of the separators 18 and 19 have rounded shapes and are smoothly connected to the upper and lower inner walls of the collection ports 10 and 12, respectively. Among the upper and lower R parts, the radius R1 of the lower R part has a larger radius of curvature than the radius R0 of the upper R part, and preferably the dimensional relationship is R1≒2×
It is set to R0. More specifically, R0 is 8mm
In the case of approximately 15 mm, R1 is formed to be approximately 15 mm. Therefore, the lower R section with radius R1 is the collection port 1
Collection ports 10 and 12 extend in the 0 and 12 directions.
Connected to the bottom wall. Also, separator 1
The inner thickness t ₃ of 8, 19 is the exhaust port 11, 12, 1
This is larger than the wall thicknesses t ₁ and t ₂ of the side walls of parts 4 and 15.

The operation of the exhaust purification device of the present invention constructed as described above will be described below.

Exhaust gas sent from the inlets of #1 to #4 exhaust ports 5, 6, 7, and 8 is bent along the curvature of the passage and sent to the expansion chamber 3, as shown in FIG. At the curved part of the passage, the flow of exhaust gas is
Due to the directivity of the flow just before the curved part, the direction of the flow is bent when it hits the inner surface of the passage on the outer circumferential side of the curve. That is, #1 to #4 exhaust port 5,,
Exhaust gas entering from the inlets 7 and 8 first hits the outer circumferential inner surface A of the curved portion that bends downward, bends downward, and then bends back to the near horizontal direction again to the curved outer circumferential inner surface B of the curved portion. The liquid then bends in a substantially horizontal direction, and then hits the inner surface C of the curved portion in FIG. 2 and flows toward the expansion chamber 3.

At the portion where the main flow of the exhaust gas strongly hits the inner wall of the passage as described above, heat transfer from the exhaust gas is improved and the amount of heat received by the passage wall increases. Therefore, the passage wall becomes hotter than other parts, and the amount of thermal expansion becomes larger. Among these, at the port inner surface B portion, the port wall B receives the exhaust gas more strongly than the separators 18 and 19, and tends to expand more than the separators 18 and 19. However, since the thermal expansion of the port wall B is smoothly restrained by the extended portion of the R1 portion of the separators 18 and 19, the separators 18 and 19 and the wall B have an internal structure that attempts to equalize the difference in thermal expansion. Stress occurs. This internal stress is caused by the notch effect in areas where the shape of the separators 18, 19 changes drastically, such as the connection between the ends of the separators 18, 19 and the passage walls, and the inner walls of the separators 18, 19, such as the ends of the separators 18, 9, and the inner walls immediately after the ends of the separators 18, 9. In areas where the temperature difference between But separator 1
The R section extensions of 8 and 19 smoothly connect to the gathering port 1.
0 and 12 sides, and the closer the R section extension is to the end, the smaller the temperature difference with wall B becomes, and the difference eventually disappears, so the internal stress of wall B also decreases to R.
It becomes smaller smoothly toward the tip of the extended portion, and locally large thermal strain and stress concentration due to the thermal strain do not occur. Moreover, since the separators 18, 19 and the wall B are connected by a large radius shape, the notch effect is reduced, and local thermal stress concentration is further reduced. The radius of the R shape between the separators 18 and 19 and the port wall is usually about 8 mm when manufacturing castings.
The radius of the R shape of the lower end of separators 18 and 19 is
By forming the separator to a thickness of about 15 mm, no cracks were observed at the connection between the separator and the port wall, indicating sufficient durability.

As described above, when using the exhaust gas purification device of the present invention, an R section is provided at the upper and lower part of the separator terminal end of the exhaust port, and the lower R section is particularly extended long toward the collecting port to prevent thermal distortion due to local heating of the passage wall. This reduces the notch effect and prevents localized stress concentration in the exhaust manifold without increasing the exhaust resistance or weight of the exhaust manifold, improving the durability of the exhaust purification device. can be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an exhaust gas purification device according to an embodiment of the present invention, FIG. 2 is a plan view showing a part of the exhaust manifold section of the exhaust gas purification device of FIG. 1, and FIG. 3 1 is a front view showing a part of the exhaust manifold section in the exhaust purification device of FIG. 1, and FIG. 4 is a sectional view of the device of FIG. 2 taken along the - line. 1... Exhaust manifold, 2... Intake manifold, 3... Expansion chamber, 4... Catalytic converter, 5,
6,7,8...exhaust port, 9,11...double pipe section, 10,12...collecting port, 14...oxygen sensor, 18,19...separator, A, B...port inner wall surface, R0 , R1... The radius of curvature of the R-shaped portion at the end of the separator.

Claims (1)

[Scope of utility model registration request] The exhaust port part of the exhaust manifold is composed of an exhaust port part, a collection port part connected to the exhaust port part, and an expansion chamber from which the collection port part opens from the left and right sides, and the exhaust port part is made up of a partition wall provided vertically within the exhaust port part. In an exhaust gas purification device configured with a twin-tube structure using separators, the upper and lower parts of the ends on the side of the collecting port of the separator are rounded and smoothly connected to the inner surfaces of the upper and lower walls of the collecting port, and the ends of the separators An exhaust gas purification device characterized in that a lower R-shape is larger than an upper R-shape.