Exhaust purification device for internal combustion engine

Abstract

The invention provides an exhaust gas purification device for an internal combustion engine, which can improve the purification performance of exhaust gas without increasing the size of a catalyst, suppress the variation of each cylinder, and appropriately detect the air-fuel ratio. An exhaust purification device (1) for an internal combustion engine is provided with: an exhaust manifold (2) having one or more exhaust flow paths through which exhaust gas discharged from a plurality of cylinders flows; a catalytic converter (3) attached to the downstream side of the exhaust flow path; and a collision diffusion chamber (4) provided between the exhaust gas flow path and the catalytic converter (3) and having a collision surface (4a) in which the main flow of the exhaust gas flowing in through the exhaust gas flow path collides with the inner wall, in which a throttle section (5) having a smaller flow path cross-sectional area than the portion in which the exhaust gas flows in the collision diffusion chamber (4) is formed on the downstream side of the collision diffusion chamber (4), and in which the flow path cross-sectional area of the throttle section (5) is smaller than the flow path cross-sectional area of the exhaust gas flowing in the collision diffusion chamber (4). An air-fuel ratio sensor (7) for detecting the air-fuel ratio of the engine is provided on the downstream side of the throttle section (5).

Description

Technical Field

[0001] This invention relates to an exhaust purification device for an internal combustion engine, and more particularly to an exhaust purification device with a catalytic converter attached near an engine having an exhaust flow path, the exhaust flow path being connected to a plurality of cylinders. Background Technology

[0002] In exhaust purification devices for internal combustion engines, it is sometimes necessary to significantly offset the catalytic converter, which is located near the engine, from the center of the cylinder bank. Patent Document 1 discloses a technique for ensuring well-balanced introduction of exhaust gases into the catalytic converter even when the catalytic converter is positioned with such a large offset.

[0003] In the exhaust pipe structure of the engine with catalyst described in Patent Document 1, the exhaust gases flowing in the multiple first exhaust passages, second exhaust passages, third exhaust passages and fourth exhaust passages arranged along the cylinder are guided toward the catalytic converter by a swirling structure provided in the collection section, which is located between the first exhaust passages and the second exhaust passages.

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2014-211111 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] According to the exhaust pipe structure with catalyst in the engine described in Patent Document 1, even if the catalytic converter is significantly offset, exhaust gas can be well balanced and introduced into the catalytic converter. However, in the exhaust pipe structure described in Patent Document 1, the flow is deflected to the outside of the pipe due to the generation of swirling flow, which may prevent the effective utilization of the central part of the catalyst. In addition, the confluence of exhaust gas flows is located between the first exhaust passage and the second exhaust passage, so the flow velocity of exhaust gas flowing in the first and second exhaust passages increases, and the time that exhaust gas remains in the catalyst is shortened. Therefore, in order to ensure the purification capacity of exhaust gas, the catalyst needs to be increased, but if the catalyst is increased, the pressure loss of the entire exhaust purification system will increase.

[0009] Therefore, the applicant has filed an invention relating to a technology for improving exhaust gas purification performance without increasing the catalyst size in Japanese Patent Application No. 2022-192782. The exhaust gas purification device for an internal combustion engine in this application is an exhaust gas purification device for an internal combustion engine equipped with a catalytic converter, which has multiple cylinders and one or more exhaust passages connected to these cylinders. In this device, a diffuser (collision diffusion chamber) is provided at a confluence section connected to the downstream side of the exhaust passage to promote the jet flow of exhaust gas into the confluence section. The diffuser has a wall surface opposite to and substantially perpendicular to the flow direction of the exhaust gas at the confluence section where the exhaust ports merge. Therefore, the mainstream of the exhaust gas flowing into the diffuser collides with the wall surface of the diffuser, causing it to flow and diffuse. Therefore, according to the exhaust gas purification device for an internal combustion engine in Japanese Patent Application No. 2022-192782, in the confluence section connected to the downstream side of the exhaust passage, the mainstream exhaust gas can be diffused or dispersed to reduce its flow velocity, thereby reducing the flow velocity of the exhaust gas passing through the catalyst. Thus, improved purification performance can be achieved without increasing the catalyst size. Furthermore, in the exhaust gas purification device for an internal combustion engine in Japanese Patent Application No. 2022-192782, an air-fuel ratio sensor (A / F sensor) is installed at the point in the aforementioned confluence section where the mainstream exhaust gases flowing into the confluence section from multiple exhaust passages intersect. With this structure, the exhaust gas exiting from each cylinder collides with the air-fuel ratio sensor at a high flow velocity, thus ensuring the responsiveness of the air-fuel ratio sensor.

[0010] On the other hand, if an air-fuel ratio sensor is installed at the diffuser section, where multiple exhaust gas flows intersect in a confluence section as described above, it may be impossible to properly detect the air-fuel ratio. For example, in Figure 1 In the example shown, the exhaust purification device 100, which utilizes the invention in Japanese Patent Application No. 2022-192782, includes: an exhaust manifold 104 having three exhaust flow paths (exhaust passages) 101, 102, and 103 connected to the cylinders (not shown) of an engine; a collision diffusion chamber (diffuser) 105 connected via a connecting pipe 104b to the downstream side of the confluence section 104a of each exhaust flow path 101, 102, and 103 in the exhaust manifold 104, promoting the jetting of the mainstream (arrows a, b, c) of exhaust gas flowing into the interior from the exhaust manifold 104; and a catalytic converter 106 connected to the downstream side of the collision diffusion chamber 105. Furthermore, an air-fuel ratio sensor 107 is provided near the inlet 105a of the collision diffusion chamber 105 where exhaust gas flows in. With the exhaust purification device 100 configured in this way, the exhaust gases discharged from each cylinder of the engine experience flow deviations within the exhaust flow paths 101, 102, and 103 of the exhaust manifold 104, which is connected to the collision diffusion chamber 105. As a result, the mainstream flow path of the exhaust gases is as follows: Figure 1As indicated by arrows a, b, and c, deviations occur, and consequently, the contact state between the exhaust gas flowing from each cylinder and the air-fuel ratio sensor 107 also deviates. Furthermore, since the air-fuel ratio sensor 107 is installed in the collision diffusion chamber 105, it is possible to detect the air-fuel ratio even when the exhaust gas mixture is incomplete. Therefore, the air-fuel ratio value detected by the air-fuel ratio sensor 107 may fluctuate inappropriately, potentially hindering proper execution of air-fuel ratio-based engine combustion control.

[0011] This invention was conceived with regard to the aforementioned technical issues, and its purpose is to provide an exhaust gas purification device for an internal combustion engine that can improve the purification performance of exhaust gas without increasing the catalyst, suppress deviations in each cylinder, and appropriately detect the air-fuel ratio.

[0012] [Methods used to solve problems]

[0013] To achieve the above objectives, the exhaust gas purification device for an internal combustion engine of the present invention comprises: one or more exhaust flow paths for exhaust gases discharged from multiple cylinders; a catalytic converter attached to the downstream side of the exhaust flow paths; and a collision diffusion chamber disposed between the exhaust flow paths and the catalytic converter and having a collision surface, the collision surface being for the mainstream of the exhaust gases flowing in through the exhaust flow paths to collide with the inner wall, characterized in that a throttling section is formed on the downstream side of the exhaust gas flow direction in the collision diffusion chamber, the flow path cross-sectional area of ​​the throttling section being smaller than the flow path cross-sectional area of ​​the portion of the exhaust gas flowing in the collision diffusion chamber, and an air-fuel ratio sensor is disposed on the downstream side of the exhaust gas flow direction in the throttling section, the air-fuel ratio sensor detecting the air-fuel ratio of the engine.

[0014] Alternatively, the throttling section in this invention may be formed at a position where the inner wall surface of the throttling section is not the same as the collision surface.

[0015] Alternatively, the throttling portion in this invention may be formed at a position where a predetermined interval 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.

[0016] Furthermore, the present invention can also be configured such that a stagnation surface is formed at the portion where the gap is generated at the boundary between the collision diffusion chamber and the throttling section, and the stagnation surface inhibits the flow of the exhaust gas after colliding with the collision surface from the collision diffusion chamber to the catalytic converter.

[0017] [Invention Effects]

[0018] According to the exhaust gas purification device for an internal combustion engine of the present invention, in the collision diffusion chamber, which is connected to the downstream side of the exhaust flow path communicating with multiple cylinders and from which exhaust gases from these multiple cylinders converge, the mainstream exhaust gas can be diffused or dispersed to reduce the flow velocity, thereby reducing the flow velocity of exhaust gas passing through the catalyst. Therefore, the purification performance can be improved without increasing the catalyst size. Furthermore, in the exhaust gas purification device for an internal combustion engine of the present invention, a throttling section is formed between the collision diffusion chamber and the catalytic converter, on the downstream side of the collision diffusion chamber. An air-fuel ratio sensor is provided on the downstream side of the throttling section. By forming the throttling section on the downstream side of the collision diffusion chamber, for example near the outlet of the collision diffusion chamber from which exhaust gases flow, the exhaust gases converging from multiple cylinders are effectively diffused and mixed within the collision diffusion chamber. Furthermore, since an air-fuel ratio sensor is provided on the downstream side of the throttling section, the air-fuel ratio can be detected based on the properly mixed state of the exhaust gases within the collision diffusion chamber. Therefore, fluctuations in the detection value caused by deviations in the exhaust gas flow can be suppressed, and the air-fuel ratio can be detected appropriately.

[0019] Furthermore, the aforementioned throttling section is formed at a location where the inner wall surface of the throttling section does not align with the collision surface of the collision diffusion chamber. In other words, the throttling section is formed by separating the position of the inner wall surface of the throttling section in the collision direction from the position of the collision surface of the collision diffusion chamber in that direction by a predetermined "gap". By forming the throttling section with such a "gap", the portion of the aforementioned "gap" in the bottom surface of the collision diffusion chamber, which serves as the boundary between the collision diffusion chamber and the throttling section, becomes a retention surface that inhibits the flow of exhaust gas from the collision diffusion chamber to the catalytic converter, causing it to stagnate. Therefore, it is possible to prevent the exhaust gas colliding with the collision surface in the collision diffusion chamber from directly flowing into the catalytic converter downstream of the collision diffusion chamber, and to effectively mix the exhaust gas in the collision diffusion chamber.

[0020] Therefore, the exhaust gas purification device for the internal combustion engine according to the present invention can improve the purification performance of exhaust gas without increasing the catalyst, and can suppress the deviation of each cylinder and properly detect the air-fuel ratio. Attached Figure Description

[0021] Figure 1 This is a diagram used to illustrate a prior art issue. It is a perspective view of a conventional exhaust purification device in which an air-fuel ratio sensor is installed in the collision diffusion chamber (diffusion section).

[0022] Figure 2 This is a diagram illustrating the structure of the exhaust purification device for the internal combustion engine of the present invention, and is a perspective view showing a structure in which an air-fuel ratio sensor is provided on the downstream side of the collision diffusion chamber between the collision diffusion chamber and the catalytic converter.

[0023] Figure 3This is a diagram illustrating the structure of the exhaust purification device for the internal combustion engine of the present invention. It is a side view showing the configuration of the exhaust manifold (exhaust flow path, confluence section), throttling section, air-fuel ratio sensor, catalytic converter, and collision diffusion chamber, etc.

[0024] Figure 4 This diagram illustrates an example of the exhaust purification device for an internal combustion engine according to the present invention (an example in which a throttling section is provided near the center of the bottom surface of the collision diffusion chamber), showing that from... Figure 3 The diagram shows a schematic cross-section of the collision diffusion chamber and the throttling section, as observed in the direction of arrow C.

[0025] Figure 5 This is a diagram illustrating another example of the exhaust purification device for an internal combustion engine according to the present invention (an example in which the distance between the inner wall surface of the throttling section and the collision surface of the collision diffuser chamber is increased), showing that from... Figure 3 The diagram shows a schematic cross-section of the collision diffusion chamber and the throttling section as observed in the direction of arrow C.

[0026] Figure 6 This is a diagram illustrating another example of the exhaust purification device for an internal combustion engine according to the present invention (an example in which the cross-sectional shape of the throttling section is set to an ellipse), showing that from... Figure 3 The diagram shows a schematic cross-section of the collision diffusion chamber and the throttling section as observed in the direction of arrow C.

[0027] [Explanation of reference numerals in the attached figures]

[0028] 1. Exhaust gas purification device

[0029] 2. Exhaust manifold (exhaust flow path)

[0030] 2a (Exhaust manifold) Connection

[0031] 3 Catalytic converter

[0032] 4. Collision diffusion chamber

[0033] 4a (Collision surface of the collision diffusion chamber)

[0034] 5 Throttling section

[0035] 5a (Inner wall surface of the throttling section)

[0036] 6. Retention Surface

[0037] 7. Air-fuel ratio sensor

[0038] 100 Exhaust gas purification device [Prior art]

[0039] 101 (Exhaust manifold) Exhaust flow path

[0040] 102 (Exhaust manifold) Exhaust flow path

[0041] 103 (Exhaust manifold) Exhaust flow path

[0042] 104 Exhaust Manifold

[0043] 104a (exhaust manifold) confluence section

[0044] 104b (exhaust manifold) connecting pipe

[0045] 105 Collision Diffusion Chamber (Diffusion Section)

[0046] 105a (Inlet of the collision diffusion chamber)

[0047] 106 Catalytic Converter

[0048] 107 Air-fuel ratio sensor Detailed Implementation

[0049] Embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments shown below are merely examples of how the present invention is embodied and do not limit the scope of the invention.

[0050] In embodiments of the present invention, the internal combustion engine represented is a gasoline engine, specifically a gasoline engine having multiple cylinders and a catalytic converter attached downstream of an exhaust flow path communicating with these cylinders. Furthermore, as... Figure 2 and Figure 3 As shown, the exhaust purification device 1 of the internal combustion engine in the embodiment of the present invention includes an exhaust manifold 2, a catalytic converter 3, a collision diffusion chamber 4, a throttling section 5, a stagnation surface 6, and an air-fuel ratio sensor 7 as its main components.

[0051] The exhaust manifold 2 has multiple exhaust flow paths, a confluence section, and a connecting section 2a. The multiple exhaust flow paths are located in... Figure 2 , Figure 3 Not illustrated, but for example, it is similar to the aforementioned. Figure 1 The exhaust flow paths 101, 102, and 103 shown have the same structure. Multiple exhaust flow paths are connected to multiple cylinders (not shown) of the engine, allowing the exhaust gases from each cylinder to flow through. The confluence section is located at... Figure 2 , Figure 3 Not illustrated, but for example, it is similar to the aforementioned. Figure 1 The confluence section 104a shown has the same structure and is the part where the various exhaust flow paths in the exhaust manifold 2 merge. The connecting section 2a is the same as described above. Figure 1 The connecting pipe 104b shown has the same structure, and the exhaust manifold 2 is connected to the collision diffusion chamber 4 described later via the connecting part 2a.

[0052] Catalytic converter 3 is, for example, the one described above. Figure 1The catalytic converter 106 shown has the same structure and can adopt a conventional structure. In the embodiment of the present invention, the catalytic converter 3 is connected to the exhaust manifold 2 via the collision diffusion chamber 4 and the throttling section 5, which will be described later.

[0053] The collision diffusion chamber 4 is disposed between each exhaust flow path of the exhaust manifold 2 and the catalytic converter 3. Specifically, the collision diffusion chamber 4 is connected to the downstream side of the confluence of the exhaust manifold 2 via the connecting part 2a. Moreover, the catalytic converter 3 is connected to the downstream side of the collision diffusion chamber 4 via the throttling part 5 described later. Furthermore, in this case, "downstream side" or "upstream side" refers to the "downstream side" or "upstream side" in the flow direction of the exhaust gas in the exhaust purification device 1. For example, in Figure 3 In the example shown, the "downstream side" of the confluence of exhaust manifold 2 is Figure 3 The "downstream side" of the exhaust gas flow direction, indicated by arrow A in the straight line, becomes... Figure 3 The left side in the left-right direction. Additionally, the "downstream side" of the collision diffusion chamber 4 is... Figure 3 Arrow B in the middle straight line indicates the "downstream side" of the exhaust gas flow direction, becoming... Figure 3 The lower side in the vertical direction. Moreover, the collision diffusion chamber 4 has a collision surface 4a formed inside it.

[0054] The collision surface 4a is the part where the mainstream exhaust gas flowing into the collision diffusion chamber 4 through each exhaust flow path of the exhaust manifold 2 collides with the inner wall of the collision diffusion chamber 4. Specifically, the collision surface 4a is a roughly perpendicular wall surface opposite to the flow of exhaust gas flowing into the collision diffusion chamber 4 from the connection 2a of the exhaust manifold 2, such as... Figure 4 The diagram shows the wall surface at collision position D, where the mainstream of exhaust gas collides with the inner wall of the collision diffusion chamber 4 at an approximately right-angle entry angle. Therefore, the mainstream of exhaust gas colliding with the collision surface 4a within the collision diffusion chamber 4 is, for example, as shown... Figure 2 , Figure 3 As indicated by the arrow on the middle curve, it diffuses or disperses within the collision diffusion chamber 4.

[0055] A throttling section 5 is disposed downstream of the collision diffusion chamber 4 between the collision diffusion chamber 4 and the catalytic converter 3. Exhaust gas flowing into the collision diffusion chamber 4 and colliding with the collision surface 4a as described above flows from the collision diffusion chamber 4 through this throttling section 5 into the downstream catalytic converter 3. The throttling section 5 is configured such that its flow path cross-sectional area is smaller than the flow path cross-sectional area of ​​the portion of the exhaust gas flowing within the collision diffusion chamber 4. Specifically, as... Figure 4 As shown, the cross-sectional area CS1 of the flow path of the exhaust gas flowing out of the collision diffusion chamber 4 toward the catalytic converter 3 in the throttling section 5 is smaller than the cross-sectional area CS2 of the flow path of the exhaust gas flowing in the collision diffusion chamber 4.

[0056] Furthermore, the throttling section 5 is formed at a position where the inner wall surface (or inner diameter surface) 5a of the throttling section 5 does not coincide with the collision surface 4a of the collision diffusion chamber 4. Specifically, as... Figure 4 As shown, the throttling section 5 is formed in the direction of collision when the mainstream of the exhaust gas in the collision diffusion chamber 4 collides with the collision surface 4a of the collision diffusion chamber 4. Figure 4 The position of the inner wall surface 5a in the left-right direction (in the direction of the exhaust gas) and the position of the collision surface 4a in the collision direction are separated by a predetermined interval d. In this case, the inner wall surface 5a of the throttling section 5 is included in the collision direction of the exhaust gas as described above (in the left-right direction). Figure 4 The wall surface of the inner diameter portion of the throttling section 5, located at the point closest to the collision position D within the aforementioned collision diffusion chamber 4 (in the left-right direction). Furthermore, in Figure 4 And the following Figure 5 and Figure 6 The above is shown in the middle. Figure 3 The diagram shows the cross-sections of the collision diffusion chamber 4 and the throttling section 5 as observed in the direction of arrow C, with the shading lines representing these cross-sections omitted.

[0057] The retention surface 6 is formed on the bottom surface of the collision diffusion chamber 4 and at the boundary between the collision diffusion chamber 4 and the throttling section 5, creating the aforementioned interval d. This suppresses the flow of exhaust gas colliding with the collision surface 4a into the catalytic converter 3. In other words, as described above, the throttling section 5 is formed at a position where the inner wall surface 5a of the throttling section 5 and the collision surface 4a of the collision diffusion chamber 4 are not aligned. In other words, the throttling section 5 is formed with a predetermined interval d between the inner wall surface 5a and the collision surface 4a, thus creating the aforementioned interval d, which becomes the retention surface 6 that stagnates the flow of exhaust gas. Through this retention surface 6, the flow of exhaust gas from the collision diffusion chamber 4 to the catalytic converter 3 is suppressed. Therefore, it is possible to suppress the direct flow of exhaust gas colliding with the collision surface 4a into the downstream catalytic converter 3 within the collision diffusion chamber 4, and to effectively diffuse and mix the exhaust gas within the collision diffusion chamber 4.

[0058] The air-fuel ratio sensor 7 is a sensor used to detect the air-fuel ratio of the engine and is installed downstream of the throttle section 5. By installing the air-fuel ratio sensor 7 on the downstream side of the collision diffusion chamber 4 and the throttle section 5 as described above, the air-fuel ratio can be detected based on the properly mixed state of the exhaust gas within the collision diffusion chamber 4. Therefore, fluctuations in the detection value caused by deviations in exhaust gas flow can be suppressed, and the air-fuel ratio can be detected appropriately.

[0059] Figure 5 , Figure 6 Another structural example of the exhaust purification device 1 according to an embodiment of the present invention is shown. Figure 5 In the example shown, the gap d between the inner wall surface 5a of the throttling section 5 and the collision surface 4a of the collision diffusion chamber 4 is relatively larger (in Figure 5 In the example shown, the throttling section 5 is formed at the largest position. As the interval d increases as described above, the area of ​​the retention surface 6 formed between these intervals also increases. Therefore, due to the large area of ​​the retention surface 6, the exhaust gas that collides with the collision surface 4a in the collision diffusion chamber 4 is easily retained in the collision diffusion chamber 4, and can effectively diffuse and mix within the collision diffusion chamber 4.

[0060] In addition, Figure 6 In the example shown, the throttling section 5 is formed with an elliptical cross-sectional shape. As described above, the exhaust gas purification device 1 in the embodiment of the present invention includes a collision diffusion chamber 4 having a collision surface 4a and a throttling section 5 having an inner wall surface 5a. The flow path cross-sectional area CS1 of the throttling section 5 only needs to be smaller than the flow path cross-sectional area CS2 of the collision diffusion chamber 4. Furthermore, a gap d is provided between the collision surface 4a of the collision diffusion chamber 4 and the inner wall surface 5a of the throttling section 5, and a retention surface 6 is formed in the portion of this gap d. Therefore, as described above... Figure 6 As shown in the example, even if the cross-sectional shape of the throttling section 5 is elliptical, as long as the flow path cross-sectional area CS1 is smaller than the flow path cross-sectional area CS2, and a retention surface 6 is formed between the collision surface 4a of the collision diffusion chamber 4 and the inner wall surface 5a of the throttling section 5, it is sufficient. Therefore, within the range of the constituent requirements of the exhaust gas purification device 1 in the embodiment of the present invention as described above, the shape, size, and arrangement position of the collision diffusion chamber 4 and the throttling section 5 can be appropriately set.

[0061] As described above, in the exhaust gas purification device 1 for an internal combustion engine according to an embodiment of the present invention, in the collision diffusion chamber 4, which is connected downstream of the exhaust manifold 2 (exhaust flow path) communicating with multiple cylinders of the engine and where exhaust gases discharged from these multiple cylinders converge, the mainstream exhaust gas can be diffused or dispersed to reduce its flow velocity, thereby reducing the flow velocity of exhaust gas passing through the catalyst. Therefore, the purification performance can be improved without increasing the catalyst size.

[0062] Furthermore, in the exhaust gas purification device 1 for an internal combustion engine according to an embodiment of the present invention, a throttling section 5 is formed on the downstream side of the collision diffusion chamber 4, between the collision diffusion chamber 4 and the catalyst converter 3. An air-fuel ratio sensor 7 is also provided on the downstream side of this throttling section 5. As a result, the exhaust gases converging from multiple cylinders are effectively diffused and mixed within the collision diffusion chamber 4. Moreover, since the air-fuel ratio sensor 7 is provided on the downstream side of the throttling section 5, the air-fuel ratio can be detected based on the properly mixed state of the exhaust gases within the collision diffusion chamber 4. Therefore, fluctuations in the detection value caused by deviations in the exhaust gas flow can be suppressed, and the air-fuel ratio can be detected appropriately.

[0063] Therefore, the exhaust gas purification device 1 for an internal combustion engine according to the embodiment of the present invention can improve the purification performance of exhaust gas without increasing the catalyst, and can suppress the deviation of each of the multiple cylinders and appropriately detect the air-fuel ratio.

Claims

1. An exhaust gas purification device for an internal combustion engine, comprising: one or more exhaust flow paths for flowing exhaust gases discharged from multiple cylinders; a catalytic converter attached downstream of the exhaust flow paths; and a collision diffusion chamber disposed between the exhaust flow paths and the catalytic converter and having a collision surface, the collision surface being for the mainstream of the exhaust gases flowing through the exhaust flow paths to collide with an inner wall, characterized in that, A throttling section is formed on the downstream side of the collision diffusion chamber. The cross-sectional area of ​​this throttling section is smaller than the cross-sectional area of ​​the portion of the exhaust gas flowing within the collision diffusion chamber. An air-fuel ratio sensor is provided on the downstream side of the throttling section, which detects the air-fuel ratio of the engine.

2. The exhaust purification device for an internal combustion engine according to claim 1, characterized in that, The throttling section is formed at a position where the inner wall surface of the throttling section is not the same as the collision surface.

3. The exhaust purification device for an internal combustion engine according to claim 1 or 2, characterized in that, The throttling section is formed at a position where a predetermined interval is created between the position of the inner wall surface of the throttling section in the collision direction when the main flow collides with the collision surface and the position of the collision surface in the collision direction.

4. The exhaust purification device for an internal combustion engine according to claim 3, characterized in that, A stagnation surface is formed at the portion where the gap is created at the boundary between the collision diffusion chamber and the throttling section. This stagnation surface inhibits the flow of the exhaust gas after colliding with the collision surface into the catalytic converter.

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