Exhaust emission control apparatus for internal combustion engine

Abstract

To achieve both promotion of the diffusion of exhaust gas flowing into a catalytic converter and inhibition of stagnation of condensed water.SOLUTION: An exhaust emission control apparatus 20 of an internal combustion engine 10 has a collision diffusion chamber 70 between an exhaust manifold 30 and a cylindrical catalytic converter 50. A cylindrical connection part 40 is connected to the catalytic converter 50 with their center axes aligned. The exhaust manifold 30 is connected to a side surface of the connection part 40. At a portion of the connection part 40 where the connection part is connected to the catalytic converter 50, a constriction 60 is provided in which the inner wall of the connection part 40 swells inward to make its flow passage cross-sectional area orthogonal to the center axis smaller than that of a portion of the connection part 40 on the exhaust upstream side. The collision diffusion chamber 70 is configured by a portion of the connection part 40 on the upstream side of the constriction 60. The constriction 60 is not provided at a portion of the inner wall of the connection part 40, which is located vertically below in a mounted state to the internal combustion engine.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an exhaust gas purification device for an internal combustion engine.

Background Art

[0002] Patent Document 1 discloses an exhaust pipe structure provided with a swirl generator that collects the exhaust flowing through each exhaust pipe between each exhaust pipe of an exhaust manifold and a catalytic converter and converts the flow of the exhaust into a swirling flow. According to this exhaust pipe structure, by converting the flow of the exhaust into a swirling flow by the swirl generator, the flow of the exhaust flowing into the catalytic converter can be diffused.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of the exhaust pipe structure disclosed in Patent Document 1, during engine operation, the condensed water generated in the exhaust manifold flows into the swirl generator located below. The outflow portion that guides the exhaust to the catalytic converter is connected above the lowermost portion of the swirl generation portion. Therefore, there is a concern that condensed water may accumulate in the swirl generator.

Means for Solving the Problems

[0005] Hereinafter, means for solving the above problems and their operational effects will be described. According to one aspect of the present disclosure, there is provided an exhaust gas purification device for an internal combustion engine, in which a collision diffusion chamber is provided between an exhaust manifold and a cylindrical catalytic converter. The collision diffusion chamber causes the exhaust gas flowing from the exhaust manifold to collide with the inner wall and diffuse, and then guides the exhaust gas to the catalytic converter. A cylindrical connection part is connected to the catalytic converter with their central axes aligned. The exhaust manifold is connected to the side surface of the connection part. At the part of the connection part that is connected to the catalytic converter, a throttle is provided where the inner wall of the connection part bulges inward, reducing the cross-sectional area of the flow path perpendicular to the central axis and making it smaller than that of the upstream part of the exhaust gas in the connection part. The collision diffusion chamber is constituted by the part of the connection part upstream of the throttle. The throttle is not provided at the part of the inner wall of the connection part that is located vertically downward in the state where the internal combustion engine is mounted.

Advantages of the Invention

[0006] The exhaust gas purification device for an internal combustion engine can achieve both promotion of diffusion of exhaust gas flowing into the catalytic converter and suppression of retention of condensed water.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0008] Hereinafter, with reference to FIGS. 1 to 3, an embodiment of an exhaust gas purification device for an internal combustion engine will be described. In the drawings, the width direction of the exhaust gas purification device 20 of the internal combustion engine 10 is defined as the "left - right direction X", the length direction of the exhaust gas purification device 20 of the internal combustion engine 10 orthogonal to the width direction is defined as the "front - rear direction Y", and the height direction of the exhaust gas purification device 20 of the internal combustion engine 10 orthogonal to both the width direction and the length direction is defined as the "up - down direction Z".

[0009] <Configuration of the exhaust gas purification device 20 of the internal combustion engine 10> FIG. 1 schematically shows an exhaust gas purification device 20 of an internal combustion engine 10 mounted on a vehicle. As shown in FIG. 1, the exhaust gas purification device 20 of the internal combustion engine 10 includes an exhaust manifold 30, a cylindrical connection part 40, and a cylindrical catalytic converter 50.

[0010] The exhaust manifold 30 is configured to guide the exhaust gas generated in the internal combustion engine 10 to the catalytic converter 50. In FIG. 1, the direction in which the exhaust gas guided by the exhaust manifold 30 flows is indicated by a thick arrow.

[0011] The connection part 40 is a cylindrical part that connects the exhaust manifold 30 and the catalytic converter 50. The connection part 40 and the catalytic converter 50 are arranged with their central axes aligned. The connection part 40 is connected to the catalytic converter 50 on one of the circular bottom surfaces and to the exhaust manifold 30 on the side surface of the cylinder. At the part where the connection part 40 and the catalytic converter 50 are connected, a throttle 60 is provided by raising the inner wall of the connection part 40 inward. The exhaust gas flow path in the connection part 40 is reduced at the part where the throttle 60 is provided compared to the part upstream of the throttle 60. An impact diffusion chamber 70 is formed in a part upstream of the throttle 60 provided on the inner wall of the connection part 40 and downstream of the exhaust manifold 30.

[0012] The conflict diffusion chamber 70 is configured such that the exhaust gas flows in through the exhaust manifold 30. The exhaust gas flowing into the conflict diffusion chamber 70 collides with the inner wall of the conflict diffusion chamber 70. The exhaust gas that has collided with the inner wall of the conflict diffusion chamber 70 diffuses within the conflict diffusion chamber 70. The diffused exhaust gas flows into the downstream catalytic converter 50. A part of the diffused exhaust gas flows along the inner wall of the conflict diffusion chamber 70. At this time, the exhaust gas is redirected and diffused toward the center side of the catalytic converter 50 by the throttle 60 provided on the inner wall of the connection part 40.

[0013] The catalytic converter 50 is configured to purify harmful components contained in the exhaust gas. Examples of the harmful components contained in the exhaust gas include carbon monoxide, hydrocarbons, nitrogen oxides, etc. The exhaust gas purified within the catalytic converter 50 is discharged from the exhaust outlet 80 of the catalytic converter 50. The exhaust outlet 80 is shown in FIG. 3.

[0014] FIG. 2 is a side view of the exhaust gas purification device 20 of the internal combustion engine 10 as viewed from the direction of arrow a in FIG. 1. FIG. 3 is a front view of the exhaust gas purification device 20 of the internal combustion engine 10 as viewed from the direction of arrow b in FIG. 1. As shown in FIGS. 2 and 3, a throttle 60 is not provided in a portion of the inner wall of the connection part 40 that is vertically downward in the state where the internal combustion engine is mounted.

[0015] In FIG. 3, a virtual line extending the center line of the outlet of the exhaust manifold 30 is shown as a dashed-dotted line. As shown in FIG. 3, the outlet of the exhaust manifold 30 is provided on the lower side in the vertical direction in the connection part 40 in the state where the internal combustion engine is mounted. The throttle 60 is provided so as to extend in the circumferential direction of the connection part 40, excluding the portion of the inner wall of the connection part 40 that is vertically downward in the state where the internal combustion engine is mounted. The throttle 60 is provided in the same direction as the position where the exhaust gas flowing into the conflict diffusion chamber 70 along the dashed-dotted line collides with the inner wall of the conflict diffusion chamber 70.

[0016] <Operation of this Embodiment> As shown by the arrow in FIG. 1, the exhaust gas flowing in from the exhaust manifold 30 collides with the inner wall of the collision diffusion chamber 70 and diffuses by being redirected by the throttle 60. FIGS. 4 and 5 show, as a first comparative example, an exhaust gas purification device 20 provided with a connection part 40 without a throttle 60. FIG. 5 is a side view of the exhaust gas purification device 20 of the first comparative example as viewed from the direction of arrow a in FIG. 4. As shown in FIGS. 4 and 5, in the exhaust gas purification device 20 without a throttle 60, the exhaust gas flowing into the connection part 40 is guided to the catalytic converter 50 along the inner wall of the connection part 40. At this time, since the exhaust gas is not sufficiently diffused, the flow reaches the catalytic converter 50 in a non-uniform state. Therefore, the purification of the exhaust gas by the catalytic converter 50 is not satisfactorily performed.

[0017] On the other hand, in the present embodiment, by providing the throttle 60 on the inner wall of the connection part 40, the diffusion of the exhaust gas is promoted. As a result, the exhaust gas can reach the catalytic converter 50 without the exhaust gas flow being biased.

[0018] FIG. 6 shows, as a second comparative example, an exhaust gas purification device 20 provided with a throttle 60 over the entire circumference including vertically downward. FIG. 6 is a side view of the exhaust gas purification device 20 of Comparative Example 2 as viewed from the direction of arrow a in FIG. 1.

[0019] The exhaust gas contains moisture. Therefore, in the exhaust gas purification device 20 of Comparative Example 2, condensed water may accumulate in the collision diffusion chamber 70. As shown in FIG. 6, when the throttle 60 is provided over the entire circumference at the portion of the connection part 40 that connects to the catalytic converter 50, the condensed water in the collision diffusion chamber 70 is blocked by the throttle 60 and accumulates in the collision diffusion chamber 70.

[0020] On the other hand, in the present embodiment, the throttle 60 is not provided at the portion of the inner wall of the connection part 40 that is located vertically downward in the state of being mounted on the internal combustion engine. Thereby, it is possible to suppress the accumulation of condensed water in the collision diffusion chamber 70.

[0021] <Effects of the Present Embodiment> (1) The exhaust gas purification device 20 can achieve both the promotion of the diffusion of the exhaust gas flowing into the catalytic converter 50 and the suppression of the retention of condensed water.

[0022] (2) In the exhaust gas purification device 20 of the internal combustion engine 10, a throttle 60 is provided on the inner wall of the connection part 40 located in the same direction as the position where the exhaust gas flowing from the exhaust manifold 30 collides with the inner wall of the collision diffusion chamber 70, with respect to the central axis of the connection part 40.

[0023] The exhaust gas flowing into the collision diffusion chamber 70 is guided to the catalytic converter 50 along the inner wall of the collision diffusion chamber 70. In the exhaust gas purification device 20 of the present embodiment, since the throttle 60 is provided on the inner wall of the connection part 40 in the same direction as the position where the exhaust gas collides with the inner wall of the collision diffusion chamber 70, the diffusion of the exhaust gas can be promoted.

[0024] (3) In the exhaust gas purification device 20 of the internal combustion engine 10, at the connection part 40, the outlet of the exhaust manifold 30 is provided on the lower side in the vertical direction in the state where the internal combustion engine is mounted. In the exhaust gas purification device 20 of the internal combustion engine 10 where the throttle 60 is not provided at the portion of the inner wall of the connection part 40 located vertically below in the state where the internal combustion engine is mounted, when the exhaust gas is made to flow in from the upper side in the vertical direction in the state where the internal combustion engine is mounted, the diffusion of the exhaust gas is not sufficiently performed.

[0025] On the other hand, in the present embodiment, the outlet of the exhaust manifold 30 is provided on the lower side in the vertical direction in the connection part 40 in the state where the internal combustion engine is mounted. As a result, the exhaust gas collides with the inner wall of the collision diffusion chamber 70 on the upper side in the vertical direction in the state where the internal combustion engine is mounted. Therefore, the exhaust gas can be diffused by the throttle 60.

[0026] <Modified Example> The present embodiment can be implemented with the following modifications. The present embodiment and the following modified examples can be implemented in combination with each other within a range where there is no technical contradiction.

[0027] · A plurality of throttles 60 may be provided on the inner wall of the connecting portion 40. · When a throttle 60 is provided in the connecting portion 40, a recess may not be provided on the outer surface of the connecting portion 40.

[0028] · Although an example in which the diameter of the connecting portion 40 is smaller than the diameter of the catalytic converter 50 has been shown, the diameter of the catalytic converter 50 and the diameter of the connecting portion 40 may be equal.

Explanation of Reference Numerals

[0029] 10…Internal combustion engine, 20…Exhaust gas purification device, 30…Exhaust manifold, 40…Connecting portion, 50…Catalytic converter, 60…Throttle, 70…Collision diffusion chamber, 80…Exhaust outlet

Claims

1. An exhaust gas purification device for an internal combustion engine, in which a collision diffusion chamber is provided between an exhaust manifold and a cylindrical catalytic converter to cause the exhaust gas flowing from the exhaust manifold to collide with the inner wall and diffuse, and guide it to the catalytic converter, a cylindrical connection part is connected to the catalytic converter with their central axes aligned, the exhaust manifold is connected to the side surface of the connection part, at the part of the connection part that connects to the catalytic converter, a throttle is provided where the inner wall of the connection part bulges inward to make the cross-sectional area of the flow path perpendicular to the central axis smaller than that of the upstream part of the exhaust gas in the connection part, the collision diffusion chamber is formed by the part of the connection part upstream of the throttle, the throttle is not provided at the part of the inner wall of the connection part that is located vertically downward in the state where the internal combustion engine is mounted, An exhaust gas purification device for an internal combustion engine.

2. The throttle is provided on the inner wall of the connection part that is located in the same direction in the direction centered on the central axis as the position where the exhaust gas flowing from the exhaust manifold collides with the inner wall of the collision diffusion chamber, The exhaust gas purification device for an internal combustion engine according to Claim 1.

3. The outlet of the exhaust manifold is provided on the lower side in the vertical direction in the connection part in the state where the internal combustion engine is mounted, The exhaust gas purification device for an internal combustion engine according to Claim 1.

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