Internal combustion engine exhaust purification apparatus

Abstract

To improve exhaust gas purification performance without upsizing a catalyst volume, suppress variation among cylinders, and appropriately detect an air fuel ratio.SOLUTION: An internal combustion engine exhaust purification apparatus 1 includes: an exhaust manifold 2 having one or multiple exhaust flow paths allowing exhaust gas, exhausted from multiple cylinders, to flow; a catalytic converter 3 provided downstream of the exhaust flow path; and a collision diffusion chamber 4 having a collision surface 4a that is provided between the exhaust flow path and catalytic converter 3 and where a main flow of the exhaust gas introduced through the exhaust flow path collides with an internal wall. In the apparatus, a contraction part 5 whose flow path cross sectional area is smaller than a part where the exhaust gas flows within the collision diffusion chamber 4 is provided downstream of the collision diffusion chamber 4, and an air-fuel ratio sensor 7 for detecting an air-fuel ratio of the engine is provided downstream of the contraction part 5.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas purification device for an internal combustion engine, and more particularly to an exhaust gas purification device in which a catalytic converter is provided near an engine having exhaust passages communicating with a plurality of cylinders. [Background technology]

[0002] In exhaust purification devices for this type of internal combustion engine, the catalytic converter located near the engine may have to be positioned significantly offset from the center of the cylinder row. Patent Document 1 discloses a technique for introducing exhaust gas into the catalytic converter in a balanced manner even when the catalytic converter is positioned significantly offset. There are.

[0003] In the catalyst-equipped exhaust pipe structure of the engine described in Patent Document 1, exhaust gases flowing through the first exhaust passage, the second exhaust passage, the third exhaust passage, and the fourth exhaust passage, which are aligned along the cylinder arrangement, are all swirled and guided toward the catalytic converter by a swirling structure provided in a collection section located between the first exhaust passage and the second exhaust passage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-211111 Summary of the Invention [Problem to be solved by the invention]

[0005] The catalyst-equipped exhaust pipe structure for an engine described in Patent Document 1 is said to be able to introduce exhaust gas into the catalytic converter in a balanced manner, even if the catalytic converter is positioned with a large offset. However, with the exhaust pipe structure described in Patent Document 1, there is a concern that the flow is biased toward the outside of the pipe due to the generation of a swirling flow, which prevents effective use of the center of the catalyst. In addition, because the confluence section where the exhaust gas flows converge is located between the first and second exhaust passages, the flow velocity of the exhaust gas flowing through the first and second exhaust passages increases, shortening the time the exhaust gas remains in the catalyst. Therefore, to ensure exhaust gas purification capacity, the catalyst needs to be large, but doing so increases pressure loss throughout the entire exhaust purification system.

[0006] Therefore, in Patent Application No. 2022-192782, the present applicant proposed an invention relating to a technology for improving exhaust gas purification performance without increasing the size of the catalyst. The exhaust gas purification device for an internal combustion engine in Patent Application No. 2022-192782 is an internal combustion engine having multiple cylinders and one or more exhaust passages communicating with the multiple cylinders, and a catalytic converter attached to the engine. A diffusion section (impingement diffusion chamber) is provided at a confluence section connected to the downstream side of the exhaust passages to promote the jet flow of exhaust gas flowing into the confluence section. The diffusion section has a wall surface facing the flow direction of the exhaust gas at the confluence section where the exhaust ports converge and is approximately perpendicular to the flow direction. Therefore, the main stream of exhaust gas flowing into the diffusion section collides with the wall surface of the diffusion section, causing the flow to diffuse. Therefore, according to the exhaust gas purification device for an internal combustion engine in Patent Application No. 2022-192782, the flow velocity of the exhaust gas passing through the catalyst can be reduced by diffusing or dispersing the main stream of exhaust gas at the confluence connected to the downstream side of the exhaust passage. This allows for improved purification performance without increasing the size of the catalyst. Furthermore, in the exhaust gas purification device for an internal combustion engine in Patent Application No. 2022-192782, an air-fuel ratio sensor (A / F sensor) is provided at the location where the main streams of exhaust gas flowing into the confluence from multiple exhaust passages intersect at the confluence. With this configuration, exhaust gas discharged from each cylinder collides with the air-fuel ratio sensor at a high flow velocity, ensuring the responsiveness of the air-fuel ratio sensor.

[0007] On the other hand, if an air-fuel ratio sensor is installed in the above-mentioned confluence where multiple exhaust gas flows intersect, i.e., in the diffusion section, there is a concern that the air-fuel ratio may not be detected appropriately. For example, in the example shown in Figure 1, an exhaust purification device 100 to which the invention in Japanese Patent Application No. 2022-192782 is applied includes an exhaust manifold 104 having three exhaust flow paths (exhaust passages) 101, 102, and 103 that communicate with engine cylinders (not shown), an impingement diffusion chamber (diffusion section) 105 connected via a connecting pipe 104b to the downstream side of a confluence 104a of the exhaust flow paths 101, 102, and 103 in the exhaust manifold 104 and that promotes a jet flow of the main stream of exhaust gas (arrows a, b, and c) flowing into the interior from the exhaust manifold 104, and a catalytic converter 106 connected downstream of the impingement diffusion chamber 105. An air-fuel ratio sensor 107 is installed near the inlet 105a of the impingement diffusion chamber 105, through which the exhaust gas flows. When the exhaust purification device 100 is configured in this manner, the exhaust gas discharged from each cylinder of the engine flows unevenly in the exhaust passages 101, 102, and 103 of the exhaust manifold 104, which connects to the impingement diffusion chamber 105. As a result, the flow path of the main exhaust gas varies as shown by arrows a, b, and c in FIG. 1 , and accordingly, the state of contact between the exhaust gas flowing from each cylinder and the air-fuel ratio sensor 107 also varies. Furthermore, because the air-fuel ratio sensor 107 is installed in the impingement diffusion chamber 105, there is a possibility that the air-fuel ratio may be detected when the exhaust gas is not completely mixed. This may result in inappropriate fluctuations in the engine's air-fuel ratio value detected by the air-fuel ratio sensor 107, which may ultimately prevent appropriate engine combustion control based on the air-fuel ratio.

[0008] This invention was devised with an eye on the technical challenges described above, and aims to provide an exhaust gas purification device for an internal combustion engine that improves exhaust gas purification performance without increasing the size of the catalyst, suppresses variations between cylinders, and is capable of properly detecting the air-fuel ratio. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides an exhaust purification device for an internal combustion engine, which comprises one or more exhaust flow paths through which exhaust gases discharged from multiple cylinders flow, a catalytic converter attached downstream of the exhaust flow paths, and an impingement diffusion chamber provided between the exhaust flow path and the catalytic converter and having a collision surface against an inner wall of which the main flow of the exhaust gases flowing through the exhaust flow paths collides, wherein a throttling section having a smaller flow path cross-sectional area than the portion of the impingement diffusion chamber through which the exhaust gases flow is formed downstream of the throttling section in the flow direction of the exhaust gas, and an air-fuel ratio sensor for detecting the air-fuel ratio of the engine is provided downstream of the throttling section in the flow direction of the exhaust gas.

[0010] The throttle portion in the present invention may be formed at a position where the inner wall surface of the throttle portion and the collision surface do not coincide with each other.

[0011] Furthermore, the throttling portion in the present invention may be configured to be formed at a position where a predetermined distance is created between the position of the inner wall surface of the throttling portion in the collision direction when the main flow collides with the collision surface and the position of the collision surface in the collision direction.

[0012] Furthermore, the present invention may be configured such that a retention surface is formed at the location where the gap occurs at the boundary between the collision diffusion chamber and the throttling portion, to suppress the flow of the exhaust gas that has collided with the collision surface from the collision diffusion chamber to the catalytic converter. [Effects of the Invention]

[0013] According to the exhaust gas purification device for an internal combustion engine of the present invention, an impingement diffusion chamber connected downstream of an exhaust flow path communicating with multiple cylinders and where exhaust gases emitted from the multiple cylinders join together diffuses or disperses the main flow of exhaust gas, reducing the flow velocity and thereby reducing the flow velocity of exhaust gas passing through a catalyst. This allows for improved purification performance without increasing the size of the catalyst. Furthermore, in the exhaust gas purification device for an internal combustion engine of the present invention, a throttle portion is formed downstream of the impingement diffusion chamber between the impingement diffusion chamber and the catalytic converter, and the air-fuel ratio sensor is installed downstream of the throttle portion. The throttle portion is formed downstream of the impingement diffusion chamber, for example, near the outlet of the impingement diffusion chamber from which the exhaust gases flow out, thereby effectively diffusing and mixing the exhaust gases joined from the multiple cylinders within the impingement diffusion chamber. The air-fuel ratio sensor is installed downstream of the throttle portion, allowing the air-fuel ratio to be detected from the exhaust gases properly mixed within the impingement diffusion chamber. This suppresses fluctuations in the detected value due to variations in the exhaust gas flow, enabling appropriate air-fuel ratio detection.

[0014] The throttle portion is formed at a position where the inner wall surface of the throttle portion does not coincide with the collision surface of the impingement diffusion chamber. In other words, the throttle portion is formed with a predetermined "gap" between the position of the inner wall surface of the throttle portion in the direction of collision when the main flow of exhaust gas in the impingement diffusion chamber collides with the collision surface of the impingement diffusion chamber and the position of the collision surface of the impingement diffusion chamber in that direction. By forming the throttle portion with such a "gap," the area on the bottom surface of the impingement diffusion chamber, which is the boundary between the impingement diffusion chamber and the throttle portion, where the "gap" occurs, becomes a retention surface that suppresses and stagnates the flow of exhaust gas from the impingement diffusion chamber to the catalytic converter. This prevents exhaust gas that collides with the collision surface in the impingement diffusion chamber from directly flowing into the catalytic converter downstream of the impingement diffusion chamber, thereby enabling effective mixing of the exhaust gas within the impingement diffusion chamber.

[0015] Therefore, according to the exhaust gas purification device for an internal combustion engine of the present invention, it is possible to improve the purification performance of exhaust gas without increasing the size of the catalyst, and further, it is possible to suppress variations between cylinders and appropriately detect the air-fuel ratio. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram for explaining the problems of the conventional technology, and is a perspective view showing a conventional exhaust purification device in which an air-fuel ratio sensor is installed in an impingement diffusion chamber (diffusion section). [Figure 2] FIG. 2 is a diagram for explaining the configuration of the exhaust gas purification device for an internal combustion engine of the present invention, and is a perspective view showing a configuration in which an air-fuel ratio sensor is installed downstream of the impingement diffusion chamber, between the impingement diffusion chamber and the catalytic converter. [Figure 3] FIG. 3 is a diagram for explaining the configuration of the exhaust purification device for an internal combustion engine of the present invention, and is a side view showing the arrangement of the exhaust manifold (exhaust flow path, junction), throttling portion, air-fuel ratio sensor, catalytic converter, impingement diffusion chamber, etc. [Figure 4] FIG. 4 is a diagram for explaining an example of an exhaust purification device for an internal combustion engine according to the present invention (an example in which a throttling portion is provided near the center of the bottom surface of the impingement diffusion chamber), and is a diagram showing an image of a cross section of the impingement diffusion chamber and the throttling portion as viewed in the direction of arrow C in FIG. [Figure 5] FIG. 5 is a diagram for explaining another example of an exhaust purification device for an internal combustion engine according to the present invention (an example in which the gap between the inner wall surface of the throttling portion and the collision surface of the impingement diffusion chamber is increased), and is a diagram showing an image of a cross section of the impingement diffusion chamber and the throttling portion as viewed in the direction of arrow C in FIG. [Figure 6] FIG. 6 is a diagram for explaining another example of an exhaust purification device for an internal combustion engine according to the present invention (an example in which the cross-sectional shape of the throttling portion is elliptical), and is a diagram showing an image of the cross section of the impingement diffusion chamber and the throttling portion as viewed in the direction of arrow C in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are merely examples of specific embodiments of the present invention and are not intended to limit the scope of the present invention.

[0018] The internal combustion engine targeted in the embodiments of the present invention is typically a gasoline engine, specifically a gasoline engine having multiple cylinders and a catalytic converter attached downstream of an exhaust passage communicating with the multiple cylinders. As shown in Figures 2 and 3, an exhaust purification device 1 for an internal combustion engine in the embodiments of the present invention includes, as its main components, an exhaust manifold 2, a catalytic converter 3, an impingement diffusion chamber 4, a throttle portion 5, a retention surface 6, and an air-fuel ratio sensor 7.

[0019] The exhaust manifold 2 has multiple exhaust flow paths, a junction, and a connecting portion 2a. The multiple exhaust flow paths are not shown in FIGS. 2 and 3, but have the same configuration as, for example, exhaust flow paths 101, 102, and 103 shown in FIG. 1. The multiple exhaust flow paths are respectively connected to multiple cylinders (not shown) of the engine, and exhaust gas discharged from each cylinder flows through the junction. The junction is not shown in FIGS. 2 and 3, but has the same configuration as, for example, junction portion 104a shown in FIG. 1, and is a portion of the exhaust manifold 2 where the exhaust flow paths join together. The connecting portion 2a has the same configuration as the connecting pipe 104b shown in FIG. 1, and the exhaust manifold 2 is connected to an impingement diffusion chamber 4, which will be described later, via this connecting portion 2a.

[0020] The catalytic converter 3 may have a configuration similar to that of the catalytic converter 106 shown in Fig. 1, and may be one having a conventional configuration. The catalytic converter 3 in this embodiment of the present invention is connected to the exhaust manifold 2 via an impingement diffusion chamber 4 and a throttle portion 5, which will be described later.

[0021] The impingement diffusion chamber 4 is provided between each exhaust flow path of the exhaust manifold 2 and the catalytic converter 3. Specifically, the impingement diffusion chamber 4 is connected to the downstream side of the junction of the exhaust manifold 2 via a connecting portion 2a. Furthermore, the catalytic converter 3 is connected to the downstream side of the impingement diffusion chamber 4 via a throttle portion 5 (described later). In this case, the "downstream side" and "upstream side" refer to the "downstream side" and "upstream side" in the direction of exhaust gas flow in the exhaust purification device 1. For example, in the example shown in FIG. 3 , the "downstream side" of the junction of the exhaust manifold 2 is the "downstream side" in the direction of exhaust gas flow indicated by the straight arrow A in FIG. 3 , which is the left side in the horizontal direction of FIG. 3 . Furthermore, the "downstream side" of the impingement diffusion chamber 4 is the "downstream side" in the direction of exhaust gas flow indicated by the straight arrow B in FIG. 3 , which is the lower side in the vertical direction of FIG. 3 . The impingement diffusion chamber 4 has a collision surface 4a formed therein.

[0022] The collision surface 4a is a portion where the main stream of exhaust gas that has flowed into the impingement diffusion chamber 4 through each exhaust flow path of the exhaust manifold 2 collides with the inner wall of the impingement diffusion chamber 4. Specifically, the collision surface 4a is a nearly vertical wall surface that faces the flow of exhaust gas that flows into the impingement diffusion chamber 4 from the connecting portion 2a of the exhaust manifold 2, and as shown in Fig. 4, the collision surface 4a is a wall surface that includes a collision position D where the main stream of exhaust gas collides with the inner wall of the impingement diffusion chamber 4 at a nearly right angle. Therefore, the main stream of exhaust gas that has collided with the collision surface 4a inside the impingement diffusion chamber 4 is diffused or dispersed within the impingement diffusion chamber 4, for example, as shown by the curved arrows in Figs. 2 and 3.

[0023] The throttle section 5 is provided downstream of the impingement diffusion chamber 4, between the impingement diffusion chamber 4 and the catalytic converter 3. The exhaust gas that flows into the impingement diffusion chamber 4 and collides with the above-described collision surface 4a passes from the impingement diffusion chamber 4 through the throttle section 5 and flows into the catalytic converter 3 downstream. The throttle section 5 is formed so that its flow path cross-sectional area is smaller than the portion of the impingement diffusion chamber 4 through which the exhaust gas flows. Specifically, as shown in FIG. 4 , the flow path cross-sectional area CS1 of the portion of the impingement diffusion chamber 4 through which the exhaust gas flows as it flows toward the catalytic converter 3 is smaller than the flow path cross-sectional area CS2 of the portion of the impingement diffusion chamber 4 through which the exhaust gas flows, as shown in FIG.

[0024] Furthermore, the throttle portion 5 is formed at a position where the inner wall surface (or inner diameter surface) 5a of the throttle portion 5 does not coincide with the collision surface 4a of the collision diffusion chamber 4. Specifically, as shown in FIG. 4, the throttle portion 5 is formed at a position where a predetermined distance d is generated between the position of the inner wall surface 5a in the collision direction (left-right direction in FIG. 4) when the main flow of exhaust gas collides with the collision surface 4a of the collision diffusion chamber 4 in the collision diffusion chamber 4, and the position of the collision surface 4a in the collision direction. In this case, the inner wall surface 5a of the throttle portion 5 is the wall surface of the inner diameter part of the throttle portion 5, including the part closest to the collision position D in the collision diffusion chamber 4 in the collision direction of the exhaust gas (left-right direction in FIG. 4). Note that FIG. 4 and FIGS. 5 and 6, which will be described later, show cross-sectional images of the collision diffusion chamber 4 and the throttle portion 5 as viewed in the direction of arrow C in FIG. 3, and hatching representing the cross sections is omitted.

[0025] The retention surface 6 is formed on the bottom surface of the impingement diffusion chamber 4 at a location where the distance d is formed at the boundary between the impingement diffusion chamber 4 and the throttle section 5. This prevents the exhaust gas that has entered the impingement diffusion chamber 4 and collided with the collision surface 4a from flowing toward the catalytic converter 3. Specifically, the inner wall surface 5a of the throttle section 5 and the collision surface 4a of the impingement diffusion chamber 4 are not aligned with each other, i.e., the throttle section 5 is formed with a predetermined distance d between the inner wall surface 5a and the collision surface 4a. This location where the distance d is formed serves as the retention surface 6, which prevents the exhaust gas from flowing from the impingement diffusion chamber 4 to the catalytic converter 3. This prevents the exhaust gas that has collided with the collision surface 4a in the impingement diffusion chamber 4 from directly flowing into the downstream catalytic converter 3, effectively diffusing and mixing the exhaust gas within the impingement diffusion chamber 4.

[0026] The air-fuel ratio sensor 7 is a sensor for detecting the air-fuel ratio of the engine, and is installed downstream of the throttle section 5. By installing the air-fuel ratio sensor 7 downstream of the impingement diffusion chamber 4 and the throttle section 5 configured as described above, it is possible to detect the air-fuel ratio from exhaust gas that is in an appropriately mixed state inside the impingement diffusion chamber 4. Therefore, it is possible to suppress fluctuations in the detection value due to variations in the flow of exhaust gas, and to appropriately detect the air-fuel ratio.

[0027] 5 and 6 show another example of the configuration of the exhaust gas purification device 1 according to an embodiment of the present invention. In the example shown in FIG. 5, the constricted portion 5 is formed at a position where the distance d between the inner wall surface 5a of the constricted portion 5 and the collision surface 4a of the collision diffusion chamber 4 is relatively large (maximum in the example shown in FIG. 5). As the distance d increases, the area of ​​the retention surface 6 formed within the distance d also increases. Therefore, the large area of ​​the retention surface 6 makes it easier for exhaust gas that has collided with the collision surface 4a in the collision diffusion chamber 4 to remain within the collision diffusion chamber 4, thereby enabling the exhaust gas to be effectively diffused and mixed within the collision diffusion chamber 4.

[0028] In the example shown in FIG. 6 , the throttle section 5 is formed so that its cross-sectional shape is elliptical. As described above, the exhaust gas purification device 1 according to the embodiment of the present invention includes the impingement diffusion chamber 4 having the collision surface 4 a and the throttle section 5 having the inner wall surface 5 a. The cross-sectional flow area CS1 of the throttle section 5 is smaller than the cross-sectional flow area CS2 of the impingement diffusion chamber 4. A gap d is provided between the collision surface 4 a of the impingement diffusion chamber 4 and the inner wall surface 5 a of the throttle section 5, and the retention surface 6 is formed in the gap d. Therefore, even if the cross-sectional shape of the throttle section 5 is elliptical, the cross-sectional flow area CS1 is smaller than the cross-sectional flow area CS2, and the retention surface 6 is formed between the collision surface 4 a of the impingement diffusion chamber 4 and the inner wall surface 5 a of the throttle section 5. Therefore, the shapes and sizes of the impingement diffusion chamber 4 and the throttle section 5, as well as the positions of the impingement diffusion chamber 4 and the throttle section 5, can be appropriately determined within the scope of satisfying the structural requirements of the exhaust gas purification device 1 according to the embodiment of the present invention.

[0029] As described above, the exhaust gas purification device 1 for an internal combustion engine according to the embodiment of the present invention is connected downstream of the exhaust manifold 2 (exhaust flow path) that communicates with multiple cylinders of the engine, and in the impingement diffusion chamber 4 where the exhaust gases discharged from the multiple cylinders join, the main stream of the exhaust gas is diffused or dispersed to reduce the flow velocity, thereby reducing the flow velocity of the exhaust gas passing through the catalyst. This makes it possible to improve purification performance without increasing the size of the catalyst.

[0030] Furthermore, in the exhaust gas purification device 1 for an internal combustion engine according to the embodiment of the present invention, a throttle section 5 is formed downstream of the impingement diffusion chamber 4, between the impingement diffusion chamber 4 and the catalytic converter 3. An air-fuel ratio sensor 7 is installed downstream of the throttle section 5. This allows exhaust gases coming together from multiple cylinders to be effectively diffused and mixed within the impingement diffusion chamber 4. Since the air-fuel ratio sensor 7 is installed downstream of the throttle section 5, the air-fuel ratio is detected from exhaust gases that have been appropriately mixed within the impingement diffusion chamber 4. This makes it possible to suppress fluctuations in the detection value due to variations in the flow of exhaust gas, and to appropriately detect the air-fuel ratio.

[0031] Therefore, according to the exhaust gas purification device 1 for an internal combustion engine in this embodiment of the present invention, it is possible to improve the purification performance of exhaust gas without increasing the size of the catalyst, and further, it is possible to suppress variations among multiple cylinders and appropriately detect the air-fuel ratio. [Explanation of symbols]

[0032] 1 Exhaust gas purification device 2 Exhaust manifold (exhaust flow path) 2a (Exhaust manifold) connection 3. Catalytic converter 4 Collision diffusion chamber 4a Collision surface (of the collision diffusion chamber) 5. Constriction section 5a (throttling part) inner wall surface 6 Retention surface 7. Air-fuel ratio sensor 100 Exhaust gas purification device (prior art) 101 (Exhaust manifold) exhaust passage 102 (Exhaust manifold) exhaust flow passage 103 (Exhaust manifold) exhaust passage 104 Exhaust manifold 104a (Exhaust manifold) junction 104b (Exhaust manifold) connecting pipe 105 Collision diffusion chamber (diffusion section) 105a (impingement diffusion chamber) inlet 106 catalytic converter 107 Air-fuel ratio sensor

Claims

1. An exhaust gas purification device for an internal combustion engine, comprising: one or more exhaust flow paths through which exhaust gases discharged from a plurality of cylinders flow; a catalytic converter attached to the downstream side of the exhaust flow paths; and an impingement diffusion chamber provided between the exhaust flow paths and the catalytic converter, the impingement diffusion chamber having an impingement surface against which a main flow of the exhaust gases that has flowed in through the exhaust flow paths impinges, a throttle portion having a flow path cross-sectional area smaller than that of a portion through which the exhaust gas flows in the collision diffusion chamber is formed downstream of the collision diffusion chamber, An air-fuel ratio sensor for detecting the air-fuel ratio of the engine is provided downstream of the throttle portion. An exhaust gas purification device for an internal combustion engine.

2. 2. An exhaust gas purification device for an internal combustion engine according to claim 1, The throttle portion is formed at a position where the inner wall surface of the throttle portion and the collision surface do not coincide with each other. An exhaust gas purification device for an internal combustion engine.

3. 3. An exhaust gas purification device for an internal combustion engine according to claim 1 or 2, The throttle portion is formed at a position where a predetermined distance is generated between a position of an inner wall surface of the throttle portion in a collision direction when the main flow collides with the collision surface and a position of the collision surface in the collision direction. An exhaust gas purification device for an internal combustion engine.

4. 4. An exhaust gas purification device for an internal combustion engine according to claim 3, A retention surface is formed at a portion where the gap is formed at the boundary between the collision diffusion chamber and the throttle portion, which suppresses the flow of the exhaust gas that has collided with the collision surface toward the catalytic converter. An exhaust gas purification device for an internal combustion engine.

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