Exhaust emission control device

Abstract

To provide an exhaust emission control device that can improve emission control performance.SOLUTION: An exhaust emission control device includes: a catalyst provided on an exhaust pipe in which exhaust air of an internal combustion engine flows; a partition wall provided upstream of the catalyst in the exhaust pipe; and an openable and closable valve body. The partition wall divides the exhaust pipe into a central portion and an outer peripheral portion. The central portion and the outer peripheral portion of the exhaust pipe are separated by closing of the valve element, and the central portion and the outer peripheral portion of the exhaust pipe are connected by opening of the valve element.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an exhaust gas purification device. [Background technology]

[0002] Exhaust gas is discharged from an internal combustion engine. A catalyst for purifying the exhaust gas and an injection valve for supplying an additive such as urea water are provided in the exhaust pipe (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-231364 A Summary of the Invention [Problem to be solved by the invention]

[0004] The amount of nitrogen oxides (NOx) and other substances generated varies depending on the operating conditions of an internal combustion engine. For example, in lean-burn combustion, the air flow rate is increased compared to stoichiometric conditions. When particularly high output is required, more air is used. Under such conditions, NOx and other substances are likely to be generated. High purification performance corresponding to the operating range is required. Therefore, the objective of the present invention is to provide an exhaust purification device that can improve purification performance. [Means for solving the problem]

[0005] The above object can be achieved by an exhaust purification device comprising a catalyst provided in an exhaust pipe through which exhaust from an internal combustion engine flows, a partition wall provided in the exhaust pipe upstream of the catalyst, and a valve body provided in the partition wall that can be opened and closed, wherein the partition wall divides the exhaust pipe into a central portion and an outer peripheral portion, and when the valve body is closed, the central portion and the outer peripheral portion of the exhaust pipe are separated, and when the valve body is opened, the central portion and the outer peripheral portion of the exhaust pipe are connected. Effect of the Invention

[0006] It is possible to provide an exhaust gas purification device capable of improving purification performance. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating an exhaust gas purification device. [Diagram 2] FIG. 2 is an enlarged view of the partition wall and its surroundings. [Diagram 3] 3(a) and 3(b) are cross-sectional views illustrating an exhaust gas purification device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the exhaust gas purification device of the present embodiment will be described with reference to the drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be illustrated to be completely consistent with the actual ones. Also, in some drawings, some details may be omitted.

[0009] 1 is a schematic diagram illustrating an exhaust purification device 100. The exhaust purification device 100 is applied to an exhaust pipe 10. The exhaust pipe 10 is connected to an internal combustion engine (not shown). In the internal combustion engine, a mixture of air and fuel is burned to generate exhaust gas, and the exhaust gas flows through the exhaust pipe 10.

[0010] The exhaust purification device 100 has a catalyst 20, an injection valve 22, a mixer 24, a partition wall 26, and a valve body 30. Exhaust gas flows through the exhaust pipe 10 in the direction shown by the arrow in Fig. 1. The injection valve 22, the partition wall 26, and the catalyst 20 are provided from upstream to downstream of the exhaust pipe 10.

[0011] The exhaust pipe 10 has portions 12, 13, 14, 15, and 16. Portion 14 is located downstream of portion 12 and has a wider width than portion 12. Portion 16 is located downstream of portions 12 and 14 and has a narrower width than portion 14. Portion 13 is located between portions 12 and 14. Portion 15 is located between portions 14 and 16. Portion 13 has a tapered shape, and the width gradually increases from portion 12 to portion 14. Portion 15 has a tapered shape, and the width gradually decreases from portion 14 to portion 16.

[0012] The catalyst 20 is, for example, a selective catalytic reduction (SCR) catalyst, and is provided in the portion 14 of the exhaust pipe 10. The injector 22 is provided in the portion 12 of the exhaust pipe 10, and injects an additive, for example, urea water, into the inside of the exhaust pipe 10. The urea water is hydrolyzed by the heat of the exhaust, generating ammonia. In the catalyst 20, the ammonia reacts with NOx in the exhaust gas, generating nitrogen and water. The exhaust gas is purified.

[0013] The partition wall 26 is a cylindrical member provided inside the portions 12 and 13 of the exhaust pipe 10. At least a portion of the partition wall 26 is separated from the inner wall of the exhaust pipe 10. The portion of the partition wall 26 located in the portion 13 has a tapered shape. The valve body 30 is a plate-shaped member and can be opened and closed.

[0014] An ECU (Electronic Control Unit) 40 is electrically connected to an air flow meter 42 and the valve body 30. The air flow meter 42 is provided in an intake pipe (not shown) and detects the flow rate of air introduced into the internal combustion engine. The ECU 40 obtains the air flow rate from the air flow meter 42. The ECU 40 can open and close the valve body 30.

[0015] 2 is an enlarged view of the vicinity of the partition wall 26. The partition wall 26 is inserted into the inner wall of the portion 12 of the exhaust pipe 10 and is in contact with the inner wall of the portion 12. The partition wall 26 is spaced apart from the inner wall of the portion 13.

[0016] A plurality of valve bodies 30 are provided on the partition wall 26 so as to go around the partition wall 26. A spring 28 is provided on the surface of the valve body 30 opposite the partition wall 26. The spring 28 is a leaf spring, and is located between the valve body 30 and the inner wall of the portion 13 of the exhaust pipe 10. The spring 28 comes into contact with the inner wall of the exhaust pipe 10 and the valve body 30, and applies an elastic force to the valve body 30. The valve body 30 opens and closes in response to the elastic force of the spring 28 and the exhaust pressure.

[0017] 3(a) and 3(b) are cross-sectional views illustrating the exhaust purification device 100, looking at the partition wall 26 and the like from the upstream side of the exhaust. In Fig. 3(a), the valve body 30 is closed. In Fig. 3(b), the valve body 30 is open.

[0018] As shown in FIG. 3(a), the partition wall 26 is cylindrical and spaced apart from the inner wall of the exhaust pipe 10. A space 44 (central portion) is formed inside the partition wall 26. A space 46 (outer periphery portion) is formed between the partition wall 26 and the exhaust pipe 10. The valve body 30 is pressed by the spring 28, so it comes into contact with the partition wall 26 and closes. The spaces 44 and 46 are isolated by the partition wall 26 and the valve body 30. Exhaust gas flows into the space 44 and is less likely to flow into the space 46.

[0019] An increase in the exhaust flow rate increases the pressure inside the exhaust pipe 10. When the pressure exceeds the elastic force of the spring 28, the valve body 30 is pushed outward, opening the valve.

[0020] 3(b), the valve body 30 moves away from the partition wall 26 and opens. The space 44 inside the partition wall 26 is connected to the space 46 outside the partition wall 26. Exhaust gas flows into both the space 44 and the space 46.

[0021] According to this embodiment, as shown in Fig. 3(a), closing the valve body 30 separates a central space 44 from an outer peripheral space 46. The exhaust gas flows into the space 44 and is introduced into the center of the catalyst 20. The exhaust gas hits the center of the catalyst 20 in a concentrated manner, which promotes warming up of the catalyst 20. The warming up improves the purification performance for NOx and the like.

[0022] As shown in Fig. 3(b), when the valve body 30 opens, the space 44 and the space 46 are connected. The exhaust gas flows into the space 44 and the space 46. The cross-sectional area of ​​the catalyst 20 that the exhaust gas hits increases, thereby improving the purification performance.

[0023] The valve element 30 may open and close in response to the elastic force of the spring 28 and the exhaust pressure. The ECU 40 may open and close the valve element 30 in response to the air flow rate. If the flow rate is less than a predetermined value, the ECU 40 closes the valve element 30. If the flow rate is equal to or greater than the predetermined value, the ECU 40 opens the valve element 30.

[0024] The injector 22 is provided upstream of the partition wall 26 of the exhaust pipe 10, and injects the additive. The mixer 24 is provided between the catalyst 20 and the injector 22. The mixer 24 diffuses the additive. The additive is prevented from being unevenly distributed, and is introduced into the entire catalyst 20. Purification performance is improved. The positions of the injector 22 and the mixer 24 can be adjusted so that the additive spray is diffused.

[0025] Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0026] 10 exhaust pipe, 12, 13, 14, 15, 16 part, 20 catalyst, 22 injection valve, 24 mixer, 26 partition wall, 28 spring, 30 valve body, 40 ECU, 42 air flow meter, 44, 46 space, 100 exhaust purification device

Claims

[Claim 1] A catalyst provided in an exhaust pipe through which exhaust gas from an internal combustion engine flows; a partition wall provided in the exhaust pipe upstream of the catalyst; a valve body provided in the partition wall and capable of being opened and closed; The partition divides the exhaust pipe into a central portion and an outer circumferential portion, When the valve body is closed, the central portion and the outer circumferential portion of the exhaust pipe are separated from each other, An exhaust purification device in which the central portion and the outer circumferential portion of the exhaust pipe are connected to each other by opening the valve body.

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