JP2017110506A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently supply urea water injected into an exhaust passage to a selective reduction catalyst.SOLUTION: In an exhaust passage of an exhaust emission control device between an urea water supply section 41 for supplying urea water 46 into the exhaust passage 16 where exhaust gas G flows and a selective reduction catalyst 42 disposed on the exhaust downstream side of the urea water supply section and selectively reducing nitrogen oxide included in the exhaust gas by using the urea water as a reducing agent, a dispersion member 47 for dispersing the urea water injected from the urea water supply section is disposed. In the exhaust passage between the dispersion member 47 and the selective reduction catalyst 42, an urea water resupply member 48 for resupplying the liquid urea water in the exhaust passage into the exhaust gas is disposed. The urea water resupply member 48 includes: a contact portion 481 mounted in the exhaust passage in a contact manner; and an inclination portion 482 inclined from the contact portion toward the central direction of the exhaust passage. In the inclination portion 482, an urea rise portion 483 for raising the urea water is provided by notching the inclination portion or by boring holes in the inclination portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust purification device provided with a selective reduction catalyst.

A selective reduction catalyst (hereinafter referred to as “SCR catalyst”) is provided in the exhaust passage to purify nitrogen oxides (hereinafter referred to as “NOx”) in the lean exhaust discharged from the diesel engine which is an internal combustion engine. Exhaust gas purifiers are known. SCR catalyst, than the catalyst is hydrolyzed urea water supplied into the exhaust passage from the exhaust upstream over a catalyst to form ammonia (NH ₃₎ and, NOx in lean atmosphere exhaust by the ammonia (NH ₃₎ Is selectively reduced and purified. When such an SCR catalyst is used, the urea water is injected into the exhaust passage from the urea water supply section disposed upstream of the SCR catalyst, and a dispersion member disposed between the urea water supply means and the SCR catalyst is used. It is used to disperse urea water, promote mixing with exhaust by vaporization by exhaust heat and atomization, and supply the SCR catalyst (for example, Patent Document 1).

JP 2014-202020 A

The urea water injected into the exhaust passage may be dispersed by the dispersing member, but may be dispersed in the exhaust passage without being dispersed and supplied to the SCR catalyst.
An object of the present invention is to make it possible to efficiently supply urea water injected into an exhaust passage to a selective reduction catalyst.

  An exhaust emission control device according to the present invention includes a urea water supply unit that supplies urea water into an exhaust passage through which exhaust discharged from an internal combustion engine flows, and a urea water supply unit that is disposed on the exhaust downstream side of the urea water supply unit. A selective reduction catalyst that selectively reduces nitrogen oxides contained in the exhaust gas using urea water supplied from the reducing agent, and a urea water supply unit disposed in an exhaust passage between the urea water supply unit and the selective reduction catalyst A dispersion member that disperses the urea water injected from the exhaust gas, and a urea water resupply member that is disposed in the exhaust passage between the dispersion member and the selective reduction catalyst, and re-supplys the liquid urea water into the exhaust gas in the exhaust passage. The urea water resupply member includes a contact portion that is attached in contact with the exhaust passage, and an inclined portion that is inclined from the contact portion toward the center of the exhaust passage. Urea water by cutting or providing holes Is characterized in that urea ascender raising is formed.

  According to the present invention, the liquid urea water in the exhaust passage is raised toward the center of the exhaust passage by the urea water resupply member disposed between the dispersion member and the selective reduction catalyst, Since it is vaporized by the heat of the exhaust gas and mixed in the exhaust gas, the urea water injected into the exhaust passage can be efficiently supplied to the selective reduction catalyst.

The figure which shows schematic structure of 1st Embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a figure explaining the structure of the urea water resupply member with which an exhaust gas purification device is equipped, Comprising: (a) is a top view, (b) is a side view. The expanded sectional view which shows the rising state of the liquid urea water by the urea water resupply member. It is a figure which shows the urea water resupply member formed by joining several plate-shaped members, (a) is a top view, (b) is sectional drawing. The top view which shows the structure of the urea water resupply member provided with the urea raise part in which the density in the site | part which urea water tends to accumulate was raised. The top view which shows the structure of the urea water resupply member provided with the urea raise part in which the density in the site | part in which urea water tends to accumulate was lowered. The figure which shows schematic structure of 2nd Embodiment of the exhaust gas purification apparatus which concerns on this invention which changed the arrangement place of the urea water resupply member. The figure which shows schematic structure of 3rd Embodiment of the exhaust gas purification apparatus which concerns on this invention provided with two or more urea water resupply members. The figure which shows the list of the some modification of a urea water resupply member. (A), (b) is an enlarged view which shows the attachment structure of a urea water resupply member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In consideration of the visibility of the drawings, the constituent elements may be partially omitted or described.
The exhaust purification device 30 according to the present embodiment is applied to a multi-cylinder diesel engine (hereinafter referred to as “engine”) 1 that is an internal combustion engine mounted on a vehicle. FIG. 1 shows one of a plurality of cylinders 2 provided in the engine 1, but the other cylinders 2 have the same configuration. In the cylinder 2 of the engine 1, a piston 3 having a cavity formed on the top surface is disposed in the cylinder 2 so as to reciprocate in the vertical direction.

  The cylinder head located at the upper part of the cylinder 2 is provided with an in-cylinder injection valve 4 that is an injector for fuel injection. The in-cylinder injection valve 4 is supplied with high-pressure fuel adjusted to a predetermined fuel pressure by the common rail. This fuel is light oil which is a mixture of hydrocarbons (HC). The in-cylinder injection valve 4 has a tip projecting from the in-cylinder space of the cylinder 2 and injects high-pressure fuel into the in-cylinder space.

  The cylinder head is provided with an intake port 5 and an exhaust port 6 communicating with the in-cylinder space of the cylinder 2, and an intake valve 7 and an exhaust valve 8 for opening and closing the intake port 5 and the exhaust port 6. An intake manifold (hereinafter referred to as “intake manifold”) 9 is connected to the intake upstream side of the intake port 5. An intake passage 12 is connected to the intake upstream end of the intake manifold 9. An electronically controlled throttle valve 11 is provided in the intake passage 12. The amount of air flowing to the intake manifold 9 is adjusted according to the opening of the throttle valve 11 (throttle opening). An air filter 13 is provided in the uppermost stream of the intake passage 12, and fresh air (air) filtered by the air filter 13 is introduced into the intake passage 12.

  An exhaust manifold (hereinafter referred to as “exhaust manifold”) 15 formed so as to merge from the plurality of cylinders 2 is connected to the exhaust downstream side of the exhaust port 6. An exhaust passage 16 through which exhaust G indicated by a white arrow discharged from the engine 1 flows is connected to the exhaust downstream side of the exhaust manifold 15. An exhaust gas purification device 30 is provided in the exhaust passage 16. The exhaust G flowing through the exhaust passage 16 is purified by the exhaust purification device 30 and then discharged outside the vehicle via a muffler (not shown).

The exhaust purification device 30 according to the present embodiment includes a urea SCR (Selective Catalytic Reduction) system 40. The urea SCR system 40 includes a urea water injection valve 41 as a urea water supply unit, an SCR catalyst 42 as a selective reduction catalyst, a urea water tank 45 that stores urea water 46 to be injected from the urea water injection valve 41 in a liquid state, A mixer 47 as a dispersion member and a urea water resupply member 48 are provided.
The urea water injection valve 41 is for injecting urea water 46 as a reducing agent (additive) from its tip nozzle into a spray form and supplying it into the exhaust gas in the exhaust passage 16. A urea water tank 45 in which urea water 46 is stored is connected to the urea water injection valve 41 via a supply line 43. A urea water pump 44 is provided in the urea water tank 45, and urea water 46 is supplied to the urea water injection valve 41 by driving the urea water pump 44.

The SCR catalyst 42 is a well-known catalyst for reducing NOx, which is nitrogen oxide contained in the exhaust G, using ammonia (NH ₃ ) generated from the urea water 46. The SCR catalyst 42 is a well-known catalyst in which vanadium, molybdenum, tungsten, zeolite, or a noble metal is attached as an active catalyst component to a honeycomb structure carrier formed of ceramics, titanium oxide, or the like. In the SCR catalyst 42, urea water 46 injected from the urea water injection valve 41 into the exhaust passage 16A and diffused by the mixer 47 is hydrolyzed and pyrolyzed by the heat of the exhaust (CO (NH ₂ ) ₂ → NH. _{3 + HOCN, HOCN + H 2} O → NH 3 + CO 2) is ammonia (NH ₃₎ as a reducing agent generated by. The SCR catalyst 42 reacts with NOx in the exhaust gas on the catalyst to reduce (purify) NOx into nitrogen (N ₂ ) and water (H ₂ O).

  The mixer 47 is disposed in the exhaust passage 16 </ b> A between the urea water injection valve 41 and the SCR catalyst 42. The mixer 47 receives the urea water 46 injected from the urea water injection valve 41 and disperses it radially toward the inner surface 16 </ b> Aa of the exhaust passage 16.

The urea water 46 sprayed into the exhaust passage 16 from the urea water injection valve 41 is diffused by the mixer 47 to promote atomization and evaporate into the exhaust gas to be vaporized and finely mixed. Then, it flows uniformly into the SCR catalyst 42, contacts the SCR catalyst 42, and is used for NOx reduction. The urea water 46 that is sprayed into the exhaust passage 16A from the urea water injection valve 41 is not only transported to the SCR catalyst 42, but is also vaporized by spraying on the inner surface 16Aa of the exhaust passage 16A. Some of them become liquid without being deposited, and others are deposited on the mixer 47 and become liquid without being dispersed, and accumulate in the exhaust passage 16 in a liquid state. That is, some urea water 46 injected from the urea water injection valve 41 is not supplied to the SCR catalyst 42.
For this reason, reusing the liquid urea water 46 as a reducing agent efficiently supplies the urea water 46 injected into the exhaust passage 16A to the SCR catalyst 42 and also consumes the urea water 46. Reduction. Also, depending on the area of use of the vehicle, when the remaining amount of the urea water 46 in the urea tank 45 decreases, it is necessary to warn the driver and prohibit the engine restart. It is desired to reduce the consumption of 46. Further, if the liquid urea water 46 remains in the exhaust passage 16A, it is vaporized by the heat of the exhaust passage 16A (heat of the exhaust pipe) when the engine is stopped and becomes ammonia (NH ₃ ), and a part thereof is left as it is. It becomes the factor of ammonia slip that is discharged into the atmosphere and the factor of deposit.

  Therefore, in the exhaust purification device 30 according to the present embodiment, the urea water resupply member 48 is disposed in the exhaust passage 16A between the mixer 47 and the SCR catalyst 42. In the present embodiment, it is assumed that the exhaust passage 16A is disposed substantially horizontally. The urea water resupply member 48 resupplyes the liquid urea water 46 accumulated in the exhaust passage 16A into the exhaust G. In the present embodiment, the exhaust passage 16A is formed by an exhaust pipe having a circular cross section. For this reason, the liquid urea water 46 in the exhaust passage 16A accumulates in the bottom portion 16b which is the lowermost portion of the exhaust passage 16A.

As shown in FIGS. 2 (a) and 2 (b), the urea water resupply member 48 includes a contact portion 481 attached in contact with the inner surface 16Aa of the exhaust passage 16A, and the center of the exhaust passage 16A from the contact portion 481. It has an inclined portion 482 inclined upward in the direction (arrow A direction). The inclined portion 482 has a urea raising portion 483 that raises the liquid urea water 46.
The urea water resupply member 48 is a metal plate-like member having excellent corrosion resistance and heat resistance, such as stainless steel, and by bending a part thereof, the contact portion 481 and the inclined portion 482 are integrated with each other. Forming. The urea water resupply member 48 is attached to the bottom portion 16Ab of the exhaust passage 16A where the urea water 46 is likely to accumulate in the exhaust passage 16A by fixing the contact portion 481 with welding, screws, or the like.

In the present embodiment, the urea water resupply member 48 is arranged such that the inclined portion 482 is located on the exhaust downstream side of the contact portion 481. Of course, you may arrange | position so that the inclination part 482 may be located in the exhaust_gas | exhaustion upstream rather than the contact part 481. FIG.
The bending angle θ of the inclined portion 482 with respect to the contact portion 481 is about 5 to 60 °. This is because if the bending angle θ is increased, the area that closes the exhaust passage 16A is increased, which may hinder the flow of the exhaust G. When the flow of the exhaust gas G is inhibited, not only the urea water 46 cannot be sufficiently supplied to the SCR catalyst 42 but also the exhaust resistance increases. For this reason, in this embodiment, bending angle (theta) is prescribed | regulated to said value.

  The urea rising portion 483 of the urea water resupply member 48 shown in FIG. 2 is configured by a plurality of cuts (slits) 486 formed so as to straddle the inclined portion 482 and the contact portion 481. The slits 486 are formed at equal intervals in the width direction B of the urea water resupply member 48 so that the liquid urea water 46 accumulated in the bottom portion 16Ab can rise by capillary action. In the present embodiment, the width of each slit 486 is 0.1 to 3.0 mm. One end 483a of the urea rising portion 483 extends to the contact portion 481, and the other end 483b extends to the tip 482a of the inclined portion 482 and is opened.

  In this embodiment, since the contact portion 481 of the urea water resupply member 48 is disposed on the bottom portion 16Ab where the urea water 46 is accumulated, the bending position 485, which is the joining position between the contact portion 481 and the inclined portion 482, increases the urea. It is formed in the middle of the cut portion (slit 486) of the portion 483. For this reason, one end 483a of the urea ascending portion 483 constituted by the plurality of slits 486 is positioned to the bottom 16Ab side where the urea water 46 is accumulated, so that the urea water 46 is introduced into the urea ascending portion 483. It becomes easy to be done.

  When the urea water resupply member 48 having such a configuration is provided, the liquid urea water 46 accumulated in the bottom portion 16Ab of the exhaust passage 16A is brought into contact with the contact portion 481 of the urea water resupply member 48 as shown in FIG. From the one end 483a to the other end 483b, the urea ascending portion 483 formed by a plurality of slits 486 formed on the inclined surface 482 is raised by the action of capillary action. At this time, the urea water resupply member 48 itself is heated by the exhaust G, and the urea water 46 that rises in the urea rising portion 483 has a smaller mass than the state in which it accumulates in the bottom portion 16Ab. It becomes easy to vaporize by the heat. Further, since the liquid urea water 46 is conveyed by the urea ascending portion 483 to the central portion side (center side) of the exhaust passage 16A where the flow velocity of the exhaust G is faster than the state of being accumulated in the bottom portion 16Ab, It becomes easy to be mixed.

Therefore, the liquid urea water 46 can be reused as a reducing agent, and the urea water 46 injected into the exhaust passage 16 can be efficiently supplied to the SCR catalyst 42. It leads to reduction of consumption. Reduction of the consumption amount of the urea water 46 suppresses the driver from restarting the engine 1 or replenishing the urea water 46 due to a shortage of urea water, leading to an improvement in drivability.
Furthermore, since the liquid urea water 46 hardly remains in the exhaust passage 16A, it is possible to suppress the generation of deposits and to suppress the ammonia slip when the engine is stopped.

4A and 4B show a first modification of the urea water resupply member.
The urea water resupplying member 48 shown in FIG. 3 is composed of a single plate-like member. However, as shown in FIGS. 4 (a) and 4 (b), a plurality of plate-like members processed into the same shape are used. They may be joined together to form the urea water resupply member 48A. When joining a some plate-shaped member mutually, it joins so that the clearance gap 484 may be formed between mutual opposing surfaces. The width of the gap 484 is preferably set to a dimension that allows the urea water 46 to raise the gap 484 by capillary action. Further, when a plurality of plate-like members are joined to each other, the urea rising portions 483 and 483 formed on the inclined portions 482 of the respective plate-like members are joined so as to be shifted in the width direction B. By joining in this manner, the number of urea rising portions (slits 486) 483 formed per unit area increases, so that the accumulated liquid urea water 46 can be efficiently sucked up and returned to the exhaust G. It is preferable because it is possible.

FIG. 5 shows a second modification of the urea water resupply member. In the urea water resupply members 48 and 48A described above, the urea ascending portions 483 including the plurality of slits 486 are formed at equal intervals in the width direction B. However, in the urea water resupply member 48B according to the second modification, the urea rising portion 483 (in the central portion 482c of the inclined portion 482 located from the bottom portion 16Ab of the exhaust passage 16A in which the urea water 46 is likely to accumulate in the width direction B. The density of the slits 486) was increased, and the side portions 482d and 482e of the inclined portion 482 were formed so that the (slit 486) was sparser than the central portion 482c.
As described above, when the density of the urea rising portion 483 (slit 486) located at a portion where the urea water 46 is easily collected is increased, the accumulated liquid urea water 46 can be efficiently sucked up and returned to the exhaust G. It is preferable because it is possible.

FIG. 6 shows a third modification of the urea water resupply member. In the urea water resupply members 48 and 48A described above, the urea ascending portions 483 including the plurality of slits 486 are formed at equal intervals in the width direction B.
The liquid urea water 46 in the exhaust passage 16A flows along the inner surface 16Aa of the exhaust passage 16A and flows to the bottom surface 16Ab. Depending on the position and amount of flow, the liquid urea water 46 may be accumulated in the bottom portion 16Ab, or It is also assumed that the amount of wraparound to the inclined portion 482 is small.

For this reason, in the urea water resupply member 48C according to the third modified example, the urea rising portion 483 (slit) on the side portions 482d and 482e side of the inclined portion 482 which is the upstream side portion of the flow of the urea water 46 in the width direction B. 486) is increased in density, and the urea ascending portion 483 (slit 486) is formed to be sparser than the side portions 482d and 482e in the central portion 482c of the inclined portion 482.
As described above, when the density of the urea rising portion 483 (slit 486) positioned at the upstream side of the flow of the urea water 46 is increased, the urea water 46 flowing on the inner surface 16Aa toward the bottom portion 16Ab or the contact portion 481 at the bottom portion 16Ab. Therefore, the urea water 46 flowing to the inclined portion 482 side can be introduced and raised to the urea raising portion 483 earlier. Therefore, not only the liquid urea water 46 accumulated in the bottom portion 16Ab but also the urea water 46 flowing in the exhaust passage 16A can be efficiently sucked up and returned to the exhaust G, which is preferable.

FIG. 7 is a diagram showing a schematic configuration of the second embodiment of the exhaust purification device 30 according to the present invention in which the arrangement location of the urea water resupply member 48 is changed. In the first embodiment, the urea water resupply member 48 is disposed in the exhaust passage 16 </ b> A that is disposed horizontally on the exhaust upstream side of the SCR catalyst 42.
However, the exhaust passage 16A may be disposed in an inclined manner, and the mixer 47 may also be disposed in the inclined exhaust passage 16A. In this arrangement, when urea water 46 is injected from the urea water injection valve 41 into the exhaust passage 16 </ b> A, the sprayed urea water 46 that cannot be dispersed by the mixer 47 becomes liquid urea water 46 and is exhausted. It flows in the passage 16A toward the SCR catalyst 42. If priority is given to suppressing the occurrence of deposits, the distance of the urea water 46 flowing in a liquid state is never short.
Therefore, in the present embodiment, the urea water resupply member 48 is disposed on the bottom 16Ab immediately downstream of the mixer 47 disposed in the inclined exhaust passage 16A. It is preferable to arrange the urea water resupply member 48 at such a position because the urea water 46 flowing through the inclined bottom portion 16Ab can be efficiently sucked up and returned to the exhaust G.

  FIG. 8 is a diagram showing a schematic configuration of the third embodiment of the exhaust purification device 30 according to the present invention. In the first and second embodiments, one urea water resupply member is disposed in the exhaust passage 16 </ b> A between the mixer 47 and the SCR catalyst 42. However, if the amount of the liquid urea water 46 that is sprayed into the exhaust passage 16A and is not mixed in the exhaust G and accumulated in the bottom portion 16Ab is large, one urea water resupply member is insufficient. Is also envisaged.

For this reason, in this embodiment, a plurality of urea water resupply members are arranged in the exhaust passage 16A at intervals in the exhaust flow direction. In this embodiment, two urea water resupply members 48 having the same shape are arranged.
By arranging a plurality of urea water resupply members 48 in this way, it is possible to supply the urea water 46 injected into the exhaust passage 16A to the SCR catalyst 42 more efficiently and to consume the urea water 46. It also leads to a reduction in the amount. Reduction of the consumption amount of the urea water 46 suppresses the driver from restarting the engine 1 or replenishing the urea water 46 due to a shortage of urea water, thereby further improving drivability.
Furthermore, since the liquid urea water 46 is less likely to remain in the exhaust passage 16A, it is possible to suppress the generation of deposits and to further suppress ammonia slip when the engine is stopped.

FIG. 9 is a diagram showing a list of a plurality of modified examples of the urea water resupply member. The urea water resupply member shown in FIGS. 9A and 9B is the urea water resupply member 48 and the urea water resupply member 48A that have already been described. The urea water resupply member 48 and the urea water resupply member 48A are referred to as a slit type for convenience.
9C and 9D show a urea water resupply member 48D, 48E that includes a contact portion 481 and an inclined portion 482, and a urea rising portion 483 formed in the inclined portion 482 is configured by a plurality of grooves 487. Indicates. The width of each groove 487 was formed wider in the width direction B than the urea water resupply members 48 and 48A. The urea water resupply member 48D is composed of a single plate-like member, whereas the urea water resupply member 48E is processed into the same shape as the urea water resupply member 48D, like the urea water resupply member 48A. A plurality of plate-like members joined together. That is, here, two urea water resupply members 48D are stacked to form the urea water resupply member 48E. These urea water resupply members 48D and 48E are referred to as comb type for convenience.

9E and 9F show a urea water resupply member 48F, 48G that includes a contact portion 481 and an inclined portion 482, and is configured by a plurality of holes 488 of the urea rising portion 483 formed in the inclined portion 482. Indicates. The urea water resupply member 48F is composed of a single plate-like member, whereas the urea water resupply member 48G has the same shape as the urea water resupply member 48A, like the urea water resupply member 48A. A plurality of processed plate-like members are joined together. That is, here, the urea water resupply member 48G is configured by stacking two urea water resupply members 48F. These urea water resupply members 48F and 48G are referred to as hole types for convenience. The diameter of each hole 488 is in the range of 2 mm to around 10 mm. Of course, a large number of holes 488 having the same diameter may be formed, or a combination of holes 488 having different diameters may be formed. In the case of the urea water resupply member 48F, the urea water 46 that has flowed from the contact portion 481 to the inclined surface 482 accumulates in the lowermost hole 488 rather than ascending the urea ascending portion 483 by capillary action, and the surface tension. It is assumed that the urea water 46 formed in the form of droplets moves to the adjacent holes 488 sequentially and rises toward the tip 482a of the inclined surface 482. For this reason, it is preferable that the interval between the holes 488 constituting the urea rising portion 483 is an interval at which the urea water 46 that has become droplets due to surface tension can move.
Alternatively, the urea rising portion 483 may be formed by forming a plurality of holes 488 on the inclined surface 482 and forming a slit so that at least the adjacent holes 488 communicate with each other. In this case, the liquid urea water 46 can be raised toward the tip 482a of the inclined surface 482 in the current state of the capillary tube.
In the urea water resupplying member 48G, two urea water resupplying members 48F, which are the same plate-like member, are joined together in an overlapped manner, so that by forming a gap 484 in which a capillary phenomenon occurs between each other, The urea water 46 can be raised toward the tip 482a of the inclined surface 482 in the current state of the capillary tube.

  9 (g) and FIG. 9 (h) are provided with a contact portion 481 and an inclined portion 482, the inclined portion 482 is formed by a plurality of protrusions 489, and urea water formed as a urea rising portion 483 between each protrusion 489. Resupply members 48H and 48I are shown. Each protrusion 489 is formed in a mountain shape that tapers toward the tip 482 a of the inclined surface 482. The urea water resupply member 48H is composed of a single plate member, whereas the urea water resupply member 48I is a plurality of plate members processed into the same shape as the urea water resupply member 48A. Are joined together. That is, here, the urea water resupply member 48I is configured by stacking two urea water resupply members 48H. These urea water resupply members 48H and 48I are referred to as tree types for convenience.

  When the inclined surface 482 is formed by the plurality of protrusions 489 formed in such a mountain shape and the space between the adjacent protrusions 489 is configured as the urea rising portion 483, the urea introduced into the urea rising portion 483 from the bending position 485 The water 46 rises toward the tip of the protrusion 489 due to surface tension, capillary action, or the like. Moreover, since the protrusion 489 has a thin tip, it is preferable because the urea water 46 is easily vaporized when heated by exhaust gas.

  Even in the case of the urea water resupply members shown in FIGS. 9C to 9H, the density of the grooves 487, the holes 488, and the mountain-shaped protrusions 489 are set as in the urea water resupply members 48A and 48B. It doesn't matter if you change it.

  In each embodiment and modification, the contact portion 481 is attached so as to be in close contact with the bottom portion 16Ab of the exhaust passage 16A. However, as shown in FIG. 10A, the contact portion 481 and the bottom portion 16Ab of the exhaust passage 16A. You may attach so that the space | gap 490 may be formed between. In this case, when the urea water 46 accumulated in the bottom portion 16Ab moves from the contact surface 481 side to the inclined surface 482 side, as shown in FIG. 6, it does not pass through the side portions 482d and 482e side of the inclined surface 482. It is preferable because it can be guided. Further, as shown in FIG. 10 (b) instead of the gap 490, if a heat-resistant penetrating member 491 is interposed between the contact portion 481 and the bottom portion 16Ab of the exhaust passage 16A, the bottom portion 16Ab collects. The liquid urea water 46 is preferably transmitted through the penetrating member 491 and guided to the inclined surface 482 side.

  Further, each urea water resupply member is made of a porous member such as an impregnating metal or ceramics, and a contact portion 481 is provided at a place (bottom portion 16Ab) where the urea water 46 is accumulated in the exhaust passage 16A. As a result, the liquid urea water 46 accumulated in the bottom portion 16Ab can permeate the urea water resupplying member itself and rise along the inclined surface 482. In this way, when the urea water resupply member itself is an impregnating material or a porous member, the inclined surface 482 itself functions as a urea rising portion, so that the slit 486, the groove 487, the hole 488, the chevron This is preferable because the processing of the projection 489 or the like becomes unnecessary.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments. Unless specifically limited in the above description, the present invention described in the claims is not limited. Various modifications and changes are possible within the scope of the gist.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 16 ... In exhaust passage, 41 ... Urea water supply part, 42 ... Selective reduction catalyst, 46 ... Urea water, 47 ... Dispersing member, 48, 48 ( A to I) ... urea water resupply member, 481 ... contact part, 482 ... inclined part, 482d, 482e ... part upstream of the flow of urea water, 483 ... urea rising part , 486 ... notches, 488 ... holes, A ... central direction of the exhaust passage, 482c ... sites where urea water tends to accumulate, G ... exhaust

Claims (7)

A urea water supply unit that supplies urea water into an exhaust passage through which exhaust discharged from the internal combustion engine flows;
A selective reduction catalyst that is disposed downstream of the urea water supply unit and that selectively reduces nitrogen oxides contained in the exhaust gas using the urea water supplied from the urea water supply unit as a reducing agent;
A dispersion member that is disposed in an exhaust passage between the urea water supply unit and the selective reduction catalyst, and disperses the urea water injected from the urea water supply unit;
A urea water resupply member that is disposed in an exhaust passage between the dispersion member and the selective reduction catalyst and re-supplys liquid urea water into the exhaust gas in the exhaust passage;
The urea water resupply member is
A contact portion attached in contact with the exhaust passage;
An inclined portion inclined from the contact portion toward the center of the exhaust passage,
The inclined portion is
An exhaust gas purifying device characterized in that a urea ascending portion for raising urea water is formed by cutting or providing a hole in the inclined portion.   The exhaust purification device according to claim 1, wherein the urea rising portion is formed so as to straddle the inclined portion and the contact portion.   3. The exhaust gas purification apparatus according to claim 1, wherein the urea water resupply member is arranged immediately after the exhaust gas downstream side of the dispersion member.   The urea rising portion is a portion where the urea water tends to accumulate in the exhaust passage, and the density of the urea rising portion is increased. Exhaust purification equipment.   The density of the urea rising portion is increased at a portion upstream of the flow of the liquid urea water in the exhaust passage. The exhaust emission control device according to claim 1.   The exhaust gas purification apparatus according to any one of claims 1 to 5, wherein the urea water resupply member is formed by joining a plurality of plate-like members to each other.   The exhaust purification device according to any one of claims 1 to 6, wherein a plurality of the urea water resupply members are arranged in an exhaust passage between the dispersion member and the selective reduction catalyst. .

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