Exhaust purification device

Abstract

To provide an exhaust emission control device capable of promoting atomization and evaporation of urea water in exhaust gas until the exhaust gas mixed with the urea water reaches a catalyst for urea selective catalytic reduction from an exhaust connecting pipe, and suppressing or preventing corrosion of the exhaust connecting pipe.SOLUTION: The exhaust emission control device has a diesel particulate filter 1, a urea selective catalyst reduction 2, and an exhaust connecting pipe 3 for connecting the diesel particulate filter 1 and the urea selective catalyst reduction 2, and the exhaust connecting pipe 3 has a linear part (corresponding to an intermediate part 31) extending in a direction parallel to the longitudinal direction of the exhaust emission control device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas purification device having a configuration in which a diesel particulate filter and a urea selective catalytic reduction are connected by an exhaust communication pipe. [Background technology]

[0002] For example, the exhaust purification device for a vehicle described in Patent Document 1 is configured to include a diesel particulate filter that removes soot from engine exhaust gas, a urea reduction catalyst that removes nitrogen oxides (NOx) from engine exhaust gas, an exhaust communication pipe that connects the diesel particulate filter and the urea reduction catalyst, and a urea water injector that injects urea water into this exhaust communication pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2014-148960 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, urea water injected from the urea water injector is mixed with exhaust gas flowing through the exhaust connecting pipe. However, if the urea water is not atomized and evaporated sufficiently when the exhaust gas mixed with the urea water enters the urea reduction catalyst, the effect of the urea reduction catalyst in removing nitrogen oxides from the exhaust gas will be reduced, and there is a concern that urea deposits will accumulate inside the exhaust connecting pipe, causing corrosion of the exhaust connecting pipe.

[0005] In view of the above circumstances, the present invention aims to provide an exhaust purification device that can promote atomization and evaporation of urea water in exhaust gases before the exhaust gases mixed with urea water travel from the exhaust connecting pipe to a catalyst for urea selective catalytic reduction, and that can suppress or prevent corrosion of the exhaust connecting pipe. [Means for solving the problem]

[0006] The present invention provides An exhaust purification device having a diesel particulate filter, a urea selective catalytic reduction, and an exhaust communication pipe connecting the diesel particulate filter and the urea selective catalytic reduction, wherein the exhaust communication pipe has a straight portion extending in a direction parallel to the longitudinal direction of the exhaust purification device.

[0007] In the exhaust gas purification device, it is preferable that the exhaust gas communication pipe has a straight portion extending in a direction parallel to the urea water injection direction.

[0008] The present invention also provides An exhaust purification device having a diesel particulate filter that removes soot from engine exhaust gas, a urea selective catalytic reduction device that removes nitrogen oxides from engine exhaust gas, an exhaust communication pipe that connects the diesel particulate filter and the urea selective catalytic reduction device, and a urea water injection nozzle that is provided in the exhaust communication pipe and injects urea water, wherein an exhaust deflector is provided in the exhaust communication pipe upstream of the installation position of the urea water injection nozzle in the exhaust gas flow direction.

[0009] According to this configuration, the flow of exhaust gas introduced into the exhaust communication pipe is deflected by the exhaust deflector, so that the urea water injected into the exhaust communication pipe is more efficiently mixed with the exhaust gas flowing through the exhaust communication pipe than when the exhaust deflector is not provided in the exhaust communication pipe. The mixture is mixed while being heated.

[0010] This promotes atomization and evaporation of the urea-water mixture in the exhaust gas before it reaches the urea-selective catalytic reduction device, thereby improving the effectiveness of removing nitrogen oxides from the exhaust gas by the urea-selective catalytic reduction device.In addition, this prevents urea deposits from building up in the exhaust connecting pipe, improving the effectiveness of suppressing or preventing corrosion of the exhaust connecting pipe.

[0011] In the above exhaust gas purification device, it is preferable that the exhaust communication pipe has a bent portion, and at least a portion of the exhaust deflector is installed in the bent portion.

[0012] According to this configuration, the urea water injected from the bent portion of the exhaust communication pipe toward the downstream side in the exhaust gas flow direction is agitated and mixed with the exhaust gas deflected by the exhaust deflector, thereby facilitating atomization and evaporation of the urea water in the exhaust gas.

[0013] In the above exhaust gas purification device, it is preferable that the exhaust deflector has a flow dividing portion that divides the flow of exhaust gas.

[0014] According to this configuration, the urea water injected from the bent portion of the exhaust communication pipe toward the downstream side in the exhaust gas flow direction is agitated and mixed with the exhaust gas diverted by the diverting portion, thereby facilitating atomization and evaporation of the urea water in the exhaust gas.

[0015] Furthermore, in the above-mentioned exhaust purification device, it is preferable that the exhaust deflector is configured by combining a first plate and a second plate so that they face each other, at least one of the first plate and the second plate is fixed to the inner wall side of the exhaust connecting pipe, and at least a portion of the opposing surfaces of the first plate and the second plate are spaced apart and widen as they move downstream in the exhaust gas flow direction.

[0016] According to this configuration, the exhaust gas is diverted and deflected by the first and second plates of the exhaust deflector, and this exhaust gas agitates and mixes the urea water that is sprayed from the bent portion of the exhaust connecting pipe toward the downstream side in the exhaust gas flow direction, thereby accelerating atomization and evaporation of the urea water in the exhaust gas.

[0017] In the above exhaust gas purification device, it is preferable that the exhaust gas communication pipe widens toward the central axis of the exhaust gas communication pipe.

[0018] According to this configuration, the space between the first and second plates is V-shaped, with the sharp side of the V-shape positioned upstream in the exhaust gas flow direction and the wider side positioned downstream in the exhaust gas flow direction.

[0019] As a result, exhaust gas flowing from the upstream portion of the exhaust communication pipe to the bent portion is divided into two branches, whereby the urea water sprayed from the bent portion toward the downstream side in the exhaust gas flow direction is agitated and mixed by the exhaust gas, thereby facilitating atomization and evaporation of the urea water in the exhaust gas.

[0020] In addition, in the above exhaust purification device, it is preferable that the maximum separation distance between the first plate and the second plate is set to be equal to or less than half the inner diameter dimension of the area in the exhaust connecting pipe where the exhaust deflector is installed.

[0021] According to this configuration, the exhaust gas flowing from the upstream portion of the exhaust communication pipe to the bent portion is bifurcated. When the exhaust gas is diverted into the first and second exhaust gases, pressure loss in the flow of the exhaust gas is suppressed and the flow of the exhaust gas is less likely to be obstructed.

[0022] In addition, in the above-mentioned exhaust purification device, it is preferable that the radial positions of the downstream inner ends of the first plate and the second plate are positioned closer to the inner wall of the exhaust connecting pipe than the radial positions of the upstream inner ends.

[0023] According to this configuration, it is possible to reduce vibration of the first and second plates caused by pulsation of exhaust gas flowing through the exhaust communication pipe. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide an exhaust purification device that can promote atomization and evaporation of urea water in exhaust gas mixed with urea water before the exhaust gas travels from the exhaust connecting pipe to a catalyst for urea selective catalytic reduction, and that can suppress or prevent corrosion of the exhaust connecting pipe. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing a schematic configuration of an embodiment of an exhaust gas purification device according to the present invention; [Figure 2]2 is an enlarged perspective view showing a bent portion of the exhaust communication pipe of FIG. 1. FIG. [Figure 3] 2 is a plan view of a bent portion of the exhaust communication pipe of FIG. 1. [Figure 4] This is a view seen from the direction of the arrow (4) in FIG. [Figure 5] FIG. 2 is a perspective view showing only the exhaust deflector; [Figure 6] The cross-sectional view taken along line (6)-(6) in Figure 1 shows how the urea water injected into the exhaust connecting pipe is stirred. [Figure 7] This is a vertical cross-sectional view of the exhaust connecting pipe taken along the central axis, showing how the urea water injected into the exhaust connecting pipe is agitated. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] One embodiment of the present invention is shown in Figures 1 to 7. As shown in Figure 1, the exhaust gas purification device of this embodiment includes a diesel particulate filter (hereinafter abbreviated as DPF) 1, a urea selective catalytic reduction (hereinafter abbreviated as SCR) 2, an exhaust communication pipe 3, a urea water injection nozzle 4, an exhaust deflector 5, etc.

[0028] The DPF 1 removes soot from the exhaust gas of an engine (not shown). The SCR 2 removes nitrogen oxides from the exhaust gas of the engine. The exhaust connecting pipe 3 connects the DPF 1 and the SCR 2. The urea water injection nozzle 4 injects urea water into the exhaust connecting pipe 3.

[0029] More specifically, although not shown in detail, the SCR 2 has a configuration in which an SCR catalyst and an ammonia slip catalyst are housed in a case. A tail pipe 21 is provided downstream of the case of the SCR 2. The open end of the tail pipe 21 on the downstream side is open to the atmosphere.

[0030] The exhaust communication pipe 3 has a straight intermediate section 31 in its longitudinal direction (exhaust gas flow direction), and its end on the DPF1 side (hereinafter referred to as the upstream section 32) and its end on the SCR2 side (hereinafter referred to as the downstream section 33) are bent so as to be perpendicular to the intermediate section 31.

[0031] In this exhaust connecting pipe 3, The intermediate portion 31 corresponds to the straight portion recited in claim 1, The upstream portion 32 is connected to the DPF 1, and the downstream portion 33 is connected to the SCR 2.

[0032] As shown in FIG. 3, the exhaust communication pipe 3 has a two-piece structure separated vertically along its central axis.

[0033] The urea water injection nozzle 4 is installed on the outside of a bent portion 34 connecting the intermediate portion 31 and the upstream portion 32 of the exhaust communication pipe 3.

[0034] More specifically, the urea water injection nozzle 4 is installed in a position where it injects urea water from the bent portion 34 along the central axis of the intermediate portion 31 toward the downstream portion 33, as shown in FIG.

[0035] The exhaust deflector 5 is disposed adjacent to the exhaust communication pipe 3 on the upstream side of the urea water injection nozzle 4 in the exhaust flow direction.

[0036] Specifically, the exhaust deflector 5 is disposed in a linear region spanning from the upstream portion 32 of the exhaust connecting pipe 3 to the bent portion 34 .

[0037] The exhaust deflector 5 is configured by combining first and second rectangular plates 6 and 7 so as to face each other.

[0038] Specifically, the first and second plates 6, 7 are made of, for example, metal (for example, stainless steel) and pressed into a rectangular shape.

[0039] As shown in Figures 2 and 5, the first and second plates 6, 7 are oriented vertically, with the two long sides along the vertical direction referred to as first sides 61, 71 and second sides 62, 72, and the two short sides along the horizontal direction (perpendicular to the first sides 61, 71) referred to as third sides 63, 73 and fourth sides 64, 74.

[0040] The first sides 61, 71 of the first and second plates 6, 7 are joined together, and the protruding portions on the downstream side of each first side 61, 71 are fixed in a cantilevered state by being sandwiched between the butt joints of each piece of the two-piece exhaust communication pipe 3.

[0041] As a result, each of the second sides 62, 72 is disposed on the central axis side of the exhaust communication pipe 3. The second sides 62, 72 are not joined to each other.

[0042] The third sides 63, 73 are arranged on the upstream side in the exhaust gas flow direction at the bent portion 34 of the exhaust communication pipe 3. The third sides 63, 73 are joined to each other.

[0043] The fourth sides 64, 74 are arranged on the downstream side in the exhaust gas flow direction at the bent portion 34 of the exhaust communication pipe 3. The fourth sides 64, 74 are not joined to each other.

[0044] The inner surface of the first plate 6 is spaced apart from the inner surface of the second plate 7. Specifically, the distance between each of the second sides 62, 72 increases from the upstream side to the downstream side in the exhaust gas flow direction, and the distance between each of the fourth sides 64, 74 increases from the side of each of the first sides 61, 71 to the side of each of the second sides 62, 72, i.e., toward the central axis of the exhaust connecting pipe 3.

[0045] As a result, as shown in FIGS. 3 and 5, the space created between the second sides 62 and 72 and the space created between the fourth sides 64 and 74 are both V-shaped.

[0046] In addition, in the V-shaped space formed between the second sides 62 and 72, the sharp side is the exhaust gas flow. The fourth sides 64, 74 are positioned upstream in the exhaust gas flow direction, and the wider side is positioned downstream in the exhaust gas flow direction. In addition, in the V-shaped space formed between the fourth sides 64, 74, the pointed side is positioned on the inner wall side of the exhaust connecting pipe 3, and the wider side is positioned on the central axis side of the upstream section 32 of the exhaust connecting pipe 3.

[0047] Moreover, the first plate 6 and the second plate 7 are curved so as to warp outward from the joining side to the non-joining side.

[0048] 1, the radial position of the inner end portion (corresponding to the downstream inner end portion in the claims) of each of the fourth sides 64, 74 is located closer to the inner wall of the exhaust communication pipe 3 than the radial position of the inner end portion (corresponding to the upstream inner end portion in the claims) of each of the third sides 63, 73. In other words, the radial position of the inner end portion of each of the third sides 63, 73 is located closer to the central axis of the exhaust communication pipe 3 than the radial position of the inner end portion of each of the fourth sides 64, 74. However, if the radial position of the inner end portion of each of the third sides 63, 73 protrudes too far radially inward, vibration of the first and second plates 6, 7 will be induced due to pulsation of exhaust gas.

[0049] Therefore, it is preferable that the length of each of the third sides 63, 73 be set to at least half the inner diameter of the upstream portion 32 of the exhaust communication pipe 3, and more preferably set to half.

[0050] Furthermore, if the maximum distance in the V-shaped space between the fourth sides 64, 74 is made too large, the pressure loss of the exhaust gas flow increases, and if it is made too small, the flow of exhaust gas is obstructed, weakening the exhaust gas stirring effect downstream of the exhaust deflector 5. Therefore, the maximum distance is preferably set to 1 / 2 or less of the inner diameter dimension of the upstream portion 32 of the exhaust connecting pipe 3, and more preferably set to 1 / 2.

[0051] Here, the first and second plates 6, 7 of the exhaust deflector 5 described above correspond to the flow dividing portion recited in the claims.

[0052] Next, the operation of the exhaust gas purification device configured as above will be described.

[0053] Exhaust gas emitted from an engine (not shown) passes through the DPF 1 to remove soot from the exhaust gas, and then the exhaust gas is introduced into the SCR 2 via an exhaust communication pipe 3 .

[0054] More specifically, the exhaust gas flowing through the exhaust communication pipe 3 is mixed with urea water injected from the urea water injection nozzle 4 .

[0055] Here, the exhaust gas mixed with the urea water flows from the upstream section 32 of the exhaust communication pipe 3 through the bent section 34 to the intermediate section 31, and the exhaust gas flowing from the upstream section 32 to the bent section 34 is divided into two by the exhaust deflector 5 as shown by the arrows 100 in FIG. 6.

[0056] This diverted exhaust gas is made to turn around by colliding with the rear wall surface while being guided along the inner wall surface of the bent portion 34, as shown by arrow 200 in Figure 6, thereby agitating the urea water injected from the urea water injection nozzle 4 and biasing the urea water injected from the urea water injection nozzle 4 to the semi-circumferential region on the DPF1 side (lower side in Figure 7) on the inner surface of the intermediate portion 31 of the exhaust connecting pipe 3, as shown by arrow 300 in Figure 7.

[0057] For this reason, immediately after the urea water is injected from the urea water injection nozzle 4 into the exhaust gas flowing through the exhaust communication pipe 3, the urea water can be efficiently mixed into the exhaust gas while being stirred.

[0058] This promotes atomization and evaporation of the urea water in the exhaust gas before the exhaust gas mixed with the urea water reaches the SCR 2, and also suppresses the accumulation of urea deposits in the exhaust communication pipe 3.

[0059] As described above, according to the exhaust purification device of the embodiment to which the present invention is applied, the reaction between nitrogen oxides in the exhaust gas and urea is promoted in the SCR2 compared to when the exhaust deflector 5 is not installed in the exhaust connecting pipe 3, thereby improving the effectiveness of removing nitrogen oxides from the exhaust gas by the SCR2 and suppressing the accumulation of urea deposits in the exhaust connecting pipe 3.

[0060] As a result, it is possible to contribute to improving the purification performance of the exhaust gas, and also to suppressing or preventing corrosion of the exhaust communication pipe 3.

[0061] The present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope of the claims and the equivalents thereof.

[0062] (1) In the above embodiment, an example is given in which the radial position of the inner end of each third side 63, 73 is positioned closer to the inner wall of the exhaust connecting pipe 3 than the radial position of the inner end of each fourth side 64, 74, but the present invention is not limited to this.

[0063] For example, although not shown, the radial positions of the inner ends of the third sides 63, 73 can be set to be the same as the radial positions of the inner ends of the fourth sides 64, 74.

[0064] In this embodiment as well, the same effects and advantages as those of the above embodiment can be obtained.

[0065] (2) In the above embodiment, the upstream portion 32 and the downstream portion 33 of the exhaust communication pipe 3 are bent in a direction perpendicular to the intermediate portion 31, but the present invention is not limited to this.

[0066] For example, in the exhaust communication pipe 3, it is possible to configure the downstream portion 33 so as not to bend in a direction perpendicular to the intermediate portion 31.

[0067] (3) In the above embodiment, the first and second plates 6, 7 are made of metal, but the present invention is not limited to this. For example, the first and second plates 6, 7 can be made of synthetic resin or carbon fiber reinforced resin with excellent heat resistance. [Industrial Applicability]

[0068] The present invention can be suitably used in an exhaust purification device having a configuration in which a DPF and an SCR are connected by an exhaust communication pipe. [Explanation of symbols]

[0069] 1 Diesel particulate filter 2. Selective catalytic reduction of urea 3 Exhaust connecting pipe 31 Middle section 32 Upper reaches 33 Downstream 34 Bend 4 Urea water injection nozzle 5 Exhaust deflector 6 First Plate 7 Second Plate

Claims

1. An exhaust purification device having a diesel particulate filter, a urea selective catalytic reduction device, and an exhaust communication pipe connecting the diesel particulate filter and the urea selective catalytic reduction device, The exhaust gas purification device is characterized in that the exhaust gas communication pipe has a straight portion extending in a direction parallel to the longitudinal direction of the exhaust gas purification device.

2. The exhaust gas purification device according to claim 1, The exhaust gas purification device is characterized in that the exhaust gas communication pipe has a straight portion extending in a direction parallel to the urea water injection direction.

3. The exhaust gas purification device according to claim 1 or 2, the exhaust communication pipe has a bent portion, An exhaust gas purification device, wherein at least a portion of the exhaust deflector is disposed at the bent portion.

4. The exhaust gas purification device according to any one of claims 1 to 3, The exhaust gas purifying device is characterized in that the exhaust deflector has a flow dividing portion that divides the flow of exhaust gas.

5. The exhaust gas purification device according to any one of claims 1 to 4, The exhaust deflector is configured by combining a first plate and a second plate so as to face each other, At least one of the first plate and the second plate is fixed to an inner wall side of the exhaust communication pipe, An exhaust gas purification device, wherein at least a portion of the opposing surfaces of the first plate and the second plate is spaced apart, and the surfaces are wider toward the downstream side in the exhaust gas flow direction.

6. The exhaust gas purification device according to claim 5, An exhaust gas purification device characterized in that the exhaust gas communication pipe widens toward the central axis thereof.

7. The exhaust gas purification device according to claim 5 or 6, An exhaust purification device characterized in that the maximum distance between the first plate and the second plate is set to less than half the inner diameter dimension of the area in the exhaust connecting pipe where the exhaust deflector is installed.

8. In the exhaust purification device according to any one of claims 5 to 7, An exhaust purification device characterized in that the radial positions of the downstream inner ends of the first plate and the second plate are positioned closer to the inner wall of the exhaust connecting pipe than the radial positions of the upstream inner ends.

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