JP2018017144A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, capable of inhibiting urea water from permeating a supporting member supporting a NOx catalyst and the NOx catalyst.SOLUTION: The exhaust emission control device for the internal combustion engine includes an exhaust pipe 1 through which exhaust gas from the internal combustion engine is passed, a selective reduction type NOx catalyst 2 provided in the exhaust pipe 1 via a supporting member M, an addition valve 3 for adding urea water into the exhaust pipe 1 located on the upstream side of the NOx catalyst 2, and a first recessed part 4 provided for reserving the urea water in the lower face of the exhaust pipe 1 located between the addition valve 3 and the NOx catalyst 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine including a selective reduction type NOx catalyst.

  In general, an exhaust gas purification apparatus for an internal combustion engine equipped with a selective reduction type NOx catalyst includes an addition valve for adding urea water into an exhaust pipe located upstream of the NOx catalyst. The NOx catalyst is provided in the exhaust pipe through a support member as a buffer material.

JP2013-124642A

  In the exhaust gas purifying apparatus described above, part of the urea water added from the addition valve may adhere to the lower surface portion in the exhaust pipe and flow to the downstream side of the exhaust pipe. When the urea water that has flowed to the downstream side permeates the support member, the support member expands as the urea water crystallizes thereafter. As a result, the NOx catalyst may be damaged by the stress due to the expansion.

  Further, when urea water permeates into the NOx catalyst, the urea water may subsequently crystallize, and the NOx catalyst itself may expand and be damaged.

  Therefore, the present invention was created in view of such circumstances, and an object of the present invention is to provide a support member that supports the NOx catalyst and an exhaust gas purification device for an internal combustion engine that can suppress the penetration of urea water into the NOx catalyst itself. is there.

  An exhaust gas purification apparatus for an internal combustion engine according to the present invention includes an exhaust pipe through which exhaust gas from the internal combustion engine is circulated, a selective reduction type NOx catalyst provided in the exhaust pipe via a support member, and an upstream side of the NOx catalyst. An addition valve for adding urea water into the exhaust pipe positioned; a first recess for storing urea water provided on a lower surface portion of the exhaust pipe located between the addition valve and the NOx catalyst; It is provided with.

  The exhaust pipe at a position between the addition valve and the NOx catalyst includes a first exhaust pipe, a second exhaust pipe, and a third exhaust pipe connected in order from the upstream side. The first exhaust pipe and the third exhaust pipe extend in the horizontal direction from the upstream end toward the downstream end and extend in directions opposite to each other, and the second exhaust pipe is the downstream end of the first exhaust pipe. And the upstream end of the third exhaust pipe, and the first recess is provided on the lower surface of the second exhaust pipe.

  Further, the deepest portion of the first recess is unevenly distributed on the exhaust gas outlet side of the second exhaust pipe.

  In addition, a second recess provided in the lower surface portion of the exhaust pipe located between the first recess and the NOx catalyst is further provided.

  The exhaust pipe is connected to a downstream end of the fourth exhaust pipe and a fourth exhaust pipe connected to the downstream end of the third exhaust pipe, and a fifth exhaust that houses the NOx catalyst. The fifth exhaust pipe extends horizontally from the upstream end toward the downstream end, and the third exhaust pipe and the fifth exhaust pipe extend in opposite directions, The fourth exhaust pipe connects the downstream end of the third exhaust pipe and the upstream end of the fifth exhaust pipe, and a second recess is provided in the lower surface portion of the fourth exhaust pipe.

  In addition, a second recess provided in a lower surface portion of the exhaust pipe positioned between the first recess and the NOx catalyst is further provided, and between the first recess and the second recess. The exhaust pipe located has an inclined portion that is inclined so that the downstream side is lower than the upstream side.

  According to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, urea water can be prevented from penetrating into the support member that supports the NOx catalyst and the NOx catalyst itself.

1 is a schematic configuration diagram illustrating an exhaust gas purification apparatus according to a first embodiment of the present invention. It is II-II sectional drawing of FIG. 1, and is a left view of the 1st recessed part in this invention. It is a schematic block diagram which shows the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3 and is a right side cross-sectional view of a second recess according to the present invention. It is a schematic block diagram which shows the exhaust gas purification apparatus which concerns on 3rd Embodiment which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, the up, down, front, back, left, and right directions shown in the figure coincide with the up, down, front, back, left, and right directions of a vehicle (not shown). However, these directions are merely determined for convenience of explanation.

(First embodiment)
An exhaust gas purification apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic top view of the exhaust gas purification apparatus 100 according to the first embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. In FIG. 1, the broken line X indicates the central axis of the addition valve 3, and the dotted line Y indicates a region where the first recess 4 is disposed. An arrow G indicates the flow direction of the exhaust gas.

  As shown in FIG. 1, an exhaust gas purification apparatus 100 is provided in an exhaust pipe 1 through which exhaust gas from an internal combustion engine (not shown) is circulated, and a mat member M that is a support member as a cushioning material. And a selective reduction type NOx catalyst (hereinafter referred to as “NOx catalyst”) 2. Further, the exhaust gas purification apparatus 100 includes an addition valve 3 that adds urea water into the exhaust pipe 1 located on the upstream side of the NOx catalyst 2. Further, the exhaust gas purifying apparatus 100 includes a first recess 4 provided on the lower surface portion of the exhaust pipe 1 located between the addition valve 3 and the NOx catalyst 2 and for storing urea water.

  The internal combustion engine is a multi-cylinder compression ignition internal combustion engine mounted on a vehicle, that is, a diesel engine. However, the use and type of the internal combustion engine are arbitrary. The internal combustion engine is provided with an exhaust manifold (not shown) that collects exhaust discharged from each cylinder.

  The exhaust pipe 1 has a first exhaust pipe 10, a second exhaust pipe 20, and a third exhaust pipe 30 that are sequentially connected from the upstream side at a position between the addition valve 3 and the NOx catalyst 2. The first exhaust pipe 10 and the third exhaust pipe 30 extend in the horizontal direction from the upstream end toward the downstream end, and extend in directions opposite to each other. The second exhaust pipe 20 connects the downstream end of the first exhaust pipe 10 and the upstream end of the third exhaust pipe 30.

  Specifically, the upstream exhaust pipe 5 is connected to the downstream end of the exhaust manifold, the first exhaust pipe 10 is connected to the downstream end of the upstream exhaust pipe 5, and the first exhaust pipe 10 is connected to the downstream end of the first exhaust pipe 10. Two exhaust pipes 20 are connected, and a third exhaust pipe 30 is connected to the downstream end of the second exhaust pipe 20.

  Further, the exhaust pipe 1 is connected to the downstream end of the fourth exhaust pipe 40 and the fourth exhaust pipe 40 connected to the downstream end of the third exhaust pipe 30, and serves as a catalyst casing that houses the NOx catalyst 2. The fifth exhaust pipe 50.

  Specifically, the fifth exhaust pipe 50 extends in the horizontal direction from the upstream end toward the downstream end, and the third exhaust pipe 30 and the fifth exhaust pipe 50 extend in directions opposite to each other. A downstream exhaust pipe 6 is connected to the downstream end of the fifth exhaust pipe 50.

  More specifically, the upstream side exhaust pipe 5 extends from the front toward the rear, is bent leftward in the horizontal direction at the position of the rear end portion, and has an exhaust gas outlet 5o at the downstream end thereof. An attachment portion 5 a for attaching the addition valve 3 is provided on the right side surface of the rear end portion of the upstream side exhaust pipe 5. On the other hand, the downstream side exhaust pipe 6 has an exhaust gas inlet 6i connected to the outlet of the fifth exhaust pipe 50, and is bent rearward in the horizontal direction at a position in the vicinity thereof and extends rearward.

  The addition valve 3 is detachably attached to the attachment portion 5a. Moreover, the addition valve 3 is arrange | positioned toward the left direction so that urea water may be added toward the exhaust gas outlet 5o from the position of the attachment part 5a. In particular, the addition valve 3 is arranged so as to be coaxial with the first exhaust pipe 10 as indicated by a broken line X, and adds urea water toward the exhaust gas outlet 5 o and the center of the first exhaust pipe 10. Are arranged as follows.

  The first exhaust pipe 10, the third exhaust pipe 30, and the fifth exhaust pipe 50 are arranged in parallel from the front. The second exhaust pipe 20 connects the downstream end of the first exhaust pipe 10 and the upstream end of the third exhaust pipe 30, and the fourth exhaust pipe 40 is downstream of the third exhaust pipe 30. The end and the upstream end of the fifth exhaust pipe 50 are connected.

  More specifically, the first exhaust pipe 10 is formed of a cylindrical straight pipe, has an upstream end connected to the downstream end of the upstream exhaust pipe 5, and extends leftward in the horizontal direction from the position of the upstream end. The upstream end of the first exhaust pipe 10 is connected to the downstream end of the upstream side exhaust pipe 5 by welding. However, the connection method of both is arbitrary, for example, a flange connection etc. may be sufficient (following, the same). An inlet is formed at the upstream end of the first exhaust pipe 10, and this inlet is connected to the exhaust gas outlet 5 o of the upstream exhaust pipe 5.

  The third exhaust pipe 30 is formed of a cylindrical straight pipe and extends in the horizontal direction from the left upstream end to the right downstream end behind the first exhaust pipe 10.

  The second exhaust pipe 20 is a cap-shaped member that connects the downstream end of the first exhaust pipe 10 and the upstream end of the third exhaust pipe 30. The second exhaust pipe 20 extends in the front-rear direction at a position on the left side of the first exhaust pipe 10 and the third exhaust pipe 30. The second exhaust pipe 20 has an exhaust gas inlet 20i connected to the outlet at the downstream end of the first exhaust pipe 10 on the right side surface of the front end portion thereof, and the third exhaust pipe 20 on the right side surface of the rear end portion thereof. The exhaust pipe 30 has an exhaust gas outlet 20o that is connected to the inlet of the upstream end of the exhaust pipe 30. The second exhaust pipe 20 is connected to the downstream end of the first exhaust pipe 10 and the upstream end of the third exhaust pipe 30 by welding.

  The fifth exhaust pipe 50 is formed of a cylindrical straight pipe, and extends in the horizontal direction from the right upstream end to the left downstream end behind the third exhaust pipe 30. The fifth exhaust pipe 50 has a larger inner diameter than the first exhaust pipe 10 and the third exhaust pipe 30, and the NOx catalyst 2 and the ammonia oxidation catalyst in order from the upstream side through the mat member M. 7 is installed. The downstream end of the fifth exhaust pipe 50 is connected to the upstream end of the downstream exhaust pipe 6 by welding.

  The mat member M is a heat insulating cushioning material laid between the inner peripheral surface of the fifth exhaust pipe 50 and the outer peripheral surfaces of the NOx catalyst 2 and the ammonia oxidation catalyst 7. The mat member M prevents excessive external stress from being applied to the NOx catalyst 2 and the ammonia oxidation catalyst 7, and protects them while insulating them. Although the material of the mat member M is arbitrary, for example, a heat-resistant sponge having heat resistance is used. However, the mat member M is formed of a material capable of penetrating liquid, particularly urea water.

As is well known, the NOx catalyst 2 is a catalyst for purifying nitrogen oxides NOx in the exhaust gas, and continuously reduces NOx by ammonia (NH ₃ ) generated by hydrolysis from urea water. obtain.

The ammonia oxidation catalyst 7 is a catalyst that oxidizes surplus ammonia (NH ₃ ) that has not been consumed in the reduction of NOx by the NOx catalyst ₂ to generate N ₂ .

  The fourth exhaust pipe 40 is a cap-shaped member that connects the downstream end of the third exhaust pipe 30 and the upstream end of the fifth exhaust pipe 50. The fourth exhaust pipe 40 extends in the front-rear direction at a position on the right side of the third exhaust pipe 30 and the fifth exhaust pipe 50. The fourth exhaust pipe 40 has an exhaust gas inlet 40i connected to the outlet at the downstream end of the third exhaust pipe 30 on the left side surface of the front end portion thereof, and the fifth exhaust pipe 40 on the left side surface of the rear end portion thereof. The exhaust pipe 50 has an exhaust gas outlet 40o that is connected to the inlet of the upstream end of the exhaust pipe 50. The exhaust gas outlet 40o has an inner diameter that is equal to the inner diameter of the inlet of the fifth exhaust pipe 50, and has a larger inner diameter than the exhaust gas inlet 40i. The fourth exhaust pipe 40 is connected to the downstream end of the third exhaust pipe 30 and the upstream end of the fifth exhaust pipe 50 by welding.

  The first recess 4 is provided on the lower surface portion of the second exhaust pipe 20. Specifically, the first recess 4 is formed on the entire lower surface of the second exhaust pipe 20 as indicated by a broken line Y. However, the 1st recessed part 4 shall be formed in a part of lower surface part of the 2nd exhaust pipe 20. As shown in FIG.

  FIG. 2 is a left side sectional view of the first recess 4. In FIG. 2, a two-dot chain line C1 indicates an intermediate position between the exhaust gas inlet 20i and the exhaust gas outlet 20o in the front-rear direction. In the present embodiment, the position on the front side of the two-dot chain line C1 is the exhaust gas inlet 20i side, and the position on the rear side is the exhaust gas outlet 20o side.

  As shown in FIG. 2, the first recess 4 is formed integrally with the second exhaust pipe 20, and the lower surface portion is recessed vertically downward from the front end face 21 to the rear end face 22 of the second exhaust pipe 20. It is formed in a curved shape.

  Further, the deepest portion 4 d of the first recess 4 is unevenly distributed on the exhaust gas outlet 20 o side of the second exhaust pipe 20. That is, the first recess 4 located on the exhaust gas outlet 20o side is formed so that more urea water is accumulated than on the exhaust gas inlet 20i side.

  Next, based on FIG. 1 and FIG. 2, the effect of the exhaust gas purification apparatus 100 which concerns on this embodiment is demonstrated.

  In the internal combustion engine, exhaust gas discharged from the exhaust manifold is released to the atmosphere through the exhaust pipe 1.

  The addition valve 3 adds urea water into the upstream exhaust pipe 5 and the first exhaust pipe 10 toward the inlet of the first exhaust pipe 10. The added urea water is mixed with the exhaust gas and travels straight in the left direction through the first exhaust pipe 10. Thereafter, the exhaust gas mixed with the urea water is turned 180 ° from the exhaust gas inlet 20i side to the exhaust gas outlet 20o side in the second exhaust pipe 20, and goes straight to the right in the third exhaust pipe 30. . Thereafter, the exhaust gas is turned 180 ° again from the exhaust gas inlet 40 i side to the exhaust gas outlet 40 o side in the fourth exhaust pipe 40 and flows into the fifth exhaust pipe 50. In this process, the urea water added from the addition valve 3 is mixed with the exhaust gas and evaporated to be hydrolyzed to produce ammonia.

  In the fifth exhaust pipe 50, the exhaust gas containing at least one of urea water and ammonia passes through the NOx catalyst 2. At this time, the NOx catalyst 2 reduces NOx with ammonia generated by hydrolysis of urea water.

  Excess ammonia that has not been consumed in the reduction of NOx by the NOx catalyst 2 is oxidized in contact with the ammonia oxidation catalyst 7, and release into the atmosphere is suppressed. As described above, the second and fourth exhaust pipes 20 and 40 form a curved passage that changes the flow direction of the exhaust gas by 180 ° in the horizontal direction. However, the direction and angle for changing the flow direction are not limited to 180 ° in the horizontal direction, and may be any direction and angle.

  Here, the exhaust pipe 1 of the present embodiment is formed to be bent in an S shape as a whole from the first exhaust pipe 10 to the fifth exhaust pipe 50. Therefore, the length of the exhaust pipe 1 positioned between the addition valve 3 and the NOx catalyst 2 can be increased while being configured more compactly than forming linearly. Thereby, hydrolysis of urea water is further accelerated | stimulated because urea water is fully stirred and mixed with waste gas. As a result, ammonia is efficiently generated, which is advantageous for improving the NOx purification rate in the NOx catalyst 2.

  On the other hand, part of the urea water added from the addition valve 3 may adhere to the lower surface near the inlet of the first exhaust pipe 10 in a liquid state.

  Here, suppose that the first recess 4 is not provided. In this case, the urea water adhering to the lower surface portion in the first exhaust pipe 10 is driven by the flow of the exhaust gas, and the second exhaust pipe 20, the third exhaust pipe 30, the fourth exhaust pipe 40 and the fifth exhaust pipe are driven. There is a possibility that the exhaust gas will flow sequentially through the lower surface of the exhaust pipe 50 and eventually reach the mat member M around the NOx catalyst 2 and further to the NOx catalyst 2 itself.

  When the reached urea water penetrates into the mat member M, for example, when the temperature of the exhaust gas rises in this state, the urea water that has penetrated into the mat member M crystallizes and causes the mat member M to expand. As a result, the NOx catalyst may be damaged by the stress caused by the expansion of the mat member M.

  Further, when the urea water permeates the NOx catalyst 2 directly or through the mat member M, if the urea water is crystallized in the NOx catalyst 2, the NOx catalyst 2 itself may expand and be damaged.

  However, in the present embodiment, urea water adhering to the lower surface portion of the first exhaust pipe 10 can be accumulated in the first recess 4. As a result, it is possible to suppress the urea water from reaching the third exhaust pipe 30 and eventually to the mat member M and the NOx catalyst 2, and to suppress the penetration of the urea water into the mat member M and the NOx catalyst 2. And damage to the NOx catalyst 2 due to crystallization of the permeated urea water can be suppressed or prevented.

  On the other hand, although not shown, as a technique for suppressing the penetration of urea water into the mat member M and the NOx catalyst 2, weirs are provided on the lower surface of the fifth exhaust pipe 50 located immediately upstream of the mat member M and the NOx catalyst 2. A method for blocking the intrusion of urea water by providing a plate can be considered. However, in this method, the passage area of the exhaust gas is reduced by the dam plate, so that the exhaust resistance increases, which is disadvantageous for the fuel consumption of the internal combustion engine.

  In this method, the exhaust gas may not hit the portion of the NOx catalyst located immediately downstream of the dam plate. In this case, a portion that is not used for exhaust gas purification occurs in the NOx catalyst, and thus the exhaust gas purification performance may be reduced.

  On the other hand, in this embodiment, since it is the structure which provides the 1st recessed part 4 in the lower surface part of the exhaust pipe 1, the passage area of the exhaust gas in the exhaust pipe 1 does not reduce. Therefore, exhaust resistance does not increase, which is advantageous for improving fuel consumption. Further, a portion where the exhaust gas does not hit does not occur in the NOx catalyst, which is advantageous in exhaust gas purification performance.

  In the present embodiment, the urea water stored in the first recess 4 can be scattered by the exhaust gas flowing through the second exhaust pipe 20 and mixed with the exhaust gas. Thereby, mixing of exhaust gas and urea water can be accelerated | stimulated, and the exhaust gas purification performance by the NOx catalyst 2 can be improved.

  In addition, in the present embodiment, the deepest portion 4d of the first recess 4 is unevenly distributed on the exhaust gas outlet 20o side of the second exhaust pipe 20, and in the first recess 4 than on the exhaust gas inlet 20i side. A large amount of urea water is accumulated on the exhaust gas outlet 20o side. Therefore, it is possible to suppress the urea water in the first recess 4 from flowing backward to the upstream side through the exhaust gas inlet 20i. For example, when the vehicle body rolls in the left-right direction (so-called rolling), such back flow can be suppressed.

(Second Embodiment)
Next, the exhaust gas purification apparatus 200 according to the second embodiment of the present invention will be described based on FIGS. 3 and 4. FIG. 3 is a schematic top view showing the exhaust gas purification apparatus 200 according to the second embodiment, and FIG. 4 is a sectional view taken along line IV-IV in FIG. In FIG. 3, a dotted line Z indicates a region where the second recess 8 is disposed.

  The present embodiment is configured by adding the second recess 8 to the first embodiment, and the other parts are the same. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, in the second embodiment, a second recess 8 is provided on the lower surface portion of the exhaust pipe 1 located between the first recess 4 and the NOx catalyst 2. Specifically, the second recess 8 is provided on the entire lower surface of the fourth exhaust pipe 40 as indicated by the broken line Z. However, the second recess 8 may be formed in a part of the lower surface portion of the fourth exhaust pipe 40.

  FIG. 4 is a right side cross-sectional view of the second recess 8. In FIG. 4, a two-dot chain line C2 indicates an intermediate position between the exhaust gas inlet 40i and the exhaust gas outlet 40o in the front-rear direction. In the present embodiment, the position before the broken line C2 is the exhaust gas inlet 40i side, and the rear position is the exhaust gas outlet 40o side.

  As shown in FIG. 4, the second recess 8 is formed integrally with the fourth exhaust pipe 40, and the lower surface portion is recessed vertically downward from the front end face 41 to the rear end face 42 of the fourth exhaust pipe 40. Formed as follows. Further, the deepest portion 8 d of the second recess 8 is unevenly distributed on the exhaust gas outlet 40 o side of the fourth exhaust pipe 40. As shown in FIGS. 2 and 4, the second recess 8 is formed so that the deepest portion 8 d is deeper and has a larger capacity than the first recess 4. However, the second concave portion 8 may be formed to be approximately the same as the first concave portion 4 or shallower than that and smaller in capacity.

  According to the above configuration, when the urea water stored in the first recess 4 overflows and flows downstream, the urea water can be stored in the second recess 8. Thereby, the penetration of urea water into the mat member M and the NOx catalyst 2 can be more reliably suppressed.

  The deepest portion 8 d of the second recess 8 may be unevenly distributed on the exhaust gas inlet 40 i side of the fourth exhaust pipe 40. By doing so, in the unlikely event that urea water overflows from the second recess 8, the urea water can overflow into the third exhaust pipe 30 on the upstream side, and the mat member M and the NOx catalyst 2 on the downstream side can be overflowed. It is possible to suppress the overflow of urea water toward

(Third embodiment)
Next, an exhaust gas purification apparatus 300 according to a third embodiment of the present invention will be described based on FIG. FIG. 5 shows a left side cross-section of the exhaust gas purification apparatus 300.

  The exhaust gas purification apparatus 300 is obtained by changing the shapes and structures of the exhaust pipe and the first and second recesses with respect to the exhaust gas purification apparatus 200 according to the second embodiment. Therefore, detailed descriptions of common components are omitted.

  In the third embodiment, a second recess 8 ′ is provided on the lower surface of the exhaust pipe 1 ′ located between the first recess 4 ′ and the NOx catalyst 2. Further, the exhaust pipe 1 ′ located between the first recess 4 ′ and the second recess 8 ′ has an inclined portion S that is inclined so that the downstream side is lower than the upstream side.

  Specifically, the exhaust pipe 1 ′ includes an upstream exhaust pipe 5 ′ connected to the downstream end of the exhaust manifold and a sixth exhaust pipe as a catalyst casing connected to the downstream end of the upstream exhaust pipe 5 ′. 60 and a downstream exhaust pipe (not shown) connected to the downstream end of the sixth exhaust pipe 60.

  The upstream exhaust pipe 5 ′ is formed in a cylindrical shape, and extends linearly and obliquely downward in the vertical direction from the front to the rear. Further, an exhaust gas outlet 5o 'is provided at the downstream end of the upstream side exhaust pipe 5' toward the rear in the horizontal direction.

  An attachment portion 5a 'for attaching the addition valve 3 is provided on the upper surface portion of the upstream exhaust pipe 5'. The addition valve 3 is detachably attached to the attachment portion 5a '. Further, the addition valve 3 is disposed so as to add urea water obliquely downward and downstream from the position of the attachment portion 5a '.

  On the other hand, a first concave portion 4 ′ and a second concave portion 8 ′ are provided in order from the upstream side on the lower surface portion of the upstream side exhaust pipe 5 ′.

  More specifically, a first opening 4a and a second opening 8a are formed on the lower surface of the upstream side exhaust pipe 5 'in order from the upstream side. The first recess 4 'is a cap member formed in a bowl shape, and covers the first opening 4a from below. The opening end of the first recess 4 'is connected to the opening end of the first opening 4a by welding. The second recess 8 'is a cap-shaped cap member, and covers the second opening 8a from the lower side. The opening end of the second recess 8 'is connected to the opening end of the second opening 8a by welding. The first recess 4 'and the second recess 8' may be integrally formed with the upstream exhaust pipe 5 '.

  Here, as described above, the upstream side exhaust pipe 5 ′ is arranged so as to be inclined downward in the vertical direction from the front to the rear. Therefore, in the present embodiment, the inclined portion S is provided in the upstream exhaust pipe 5 ′ from at least the position of the addition valve 3 to the downstream end position of the second recess 8 ′. Although not shown, the inclined portion S may be provided in a part between the first concave portion 4 ′ and the second concave portion 8 ′.

  On the other hand, the sixth exhaust pipe 60 extends in the horizontal direction from the front to the rear, and has a diameter-expanded portion 61 that is larger in diameter than the upstream end and the downstream end at a position between the upstream end and the downstream end. Have In the present embodiment, the sixth exhaust pipe 60 internally includes the NOx catalyst 2 and the ammonia oxidation catalyst 7 via the mat member M at the position of the enlarged diameter portion 61.

  The upstream end of the sixth exhaust pipe 60 has an inner diameter that is the same as the downstream end of the upstream exhaust pipe 5 '. The upstream end of the sixth exhaust pipe 60 and the downstream end of the upstream exhaust pipe 5 'are flange-connected by bolts and nuts (not shown). However, the connection method of both is arbitrary, for example, the connection by welding etc. may be sufficient.

  In the above configuration, the inclined portion S is provided, so that the urea water overflowing from the first concave portion 4 ′ easily flows downstream. However, in this embodiment, even in such a structure, the urea water can be stored in the second recess 8 '. Thereby, the penetration of urea water into the mat member M and the NOx catalyst 2 can be reliably suppressed.

  Further, as described above, in the present embodiment, the openings 4a and 8a are provided in the lower surface portion of the upstream exhaust pipe 5 ′ formed in a cylindrical shape and linearly, and the first recess 4 ′ and In this structure, the opening end of the second recess 8 ′ is connected. Therefore, the first concave portion 4 ′ and the second concave portion 8 ′ are separated from each other, and the processing and manufacturing thereof are easy.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, you may provide the inclination part S in the 3rd exhaust pipe 30 in 2nd Embodiment. In this case, the entire third exhaust pipe 30 may be inclined, or a part of the third exhaust pipe 30 may be inclined.

  Further, the upstream exhaust pipe 5 ′ in the third embodiment may be an exhaust pipe extending in the horizontal direction like the first to fourth exhaust pipes 10, 20, 30, and 40 in the second embodiment.

  Furthermore, the exhaust pipe according to the present invention is not limited to the one described in the above embodiment, and may have any shape, structure, orientation, arrangement, and the like. Therefore, the present invention can be applied to various exhaust pipes having various forms according to the layout of the vehicle.

DESCRIPTION OF SYMBOLS 1 Exhaust pipe 2 NOx catalyst 3 Addition valve 4 Recess 100 Exhaust gas purification apparatus M Support member (mat member)

Claims (6)

An exhaust pipe through which the exhaust gas of the internal combustion engine is circulated;
A selective reduction type NOx catalyst provided in the exhaust pipe via a support member;
An addition valve for adding urea water into the exhaust pipe located upstream of the NOx catalyst;
An exhaust gas purification apparatus for an internal combustion engine, comprising: a first recess provided in a lower surface portion of the exhaust pipe located between the addition valve and the NOx catalyst, and storing urea water. The exhaust pipe at a position between the addition valve and the NOx catalyst has a first exhaust pipe, a second exhaust pipe, and a third exhaust pipe connected in order from the upstream side,
The first exhaust pipe and the third exhaust pipe extend in the horizontal direction from the upstream end toward the downstream end, and extend in directions opposite to each other;
The second exhaust pipe connects a downstream end of the first exhaust pipe and an upstream end of the third exhaust pipe,
The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the first recess is provided in a lower surface portion of the second exhaust pipe. The exhaust gas purification apparatus for an internal combustion engine according to claim 2, wherein a deepest portion of the first recess is unevenly distributed on an exhaust gas outlet side of the second exhaust pipe. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 3, further comprising a second recess provided in a lower surface portion of the exhaust pipe positioned between the first recess and the NOx catalyst. . The exhaust pipe is
A fourth exhaust pipe connected to the downstream end of the third exhaust pipe;
A fifth exhaust pipe connected to the downstream end of the fourth exhaust pipe and containing the NOx catalyst,
The fifth exhaust pipe extends in the horizontal direction from the upstream end toward the downstream end,
The third exhaust pipe and the fifth exhaust pipe extend in opposite directions;
The fourth exhaust pipe connects the downstream end of the third exhaust pipe and the upstream end of the fifth exhaust pipe,
The exhaust gas purification apparatus for an internal combustion engine according to claim 2 or 3, wherein a second recess is provided in a lower surface portion of the fourth exhaust pipe. A second recess provided in a lower surface portion of the exhaust pipe located between the first recess and the NOx catalyst;
2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the exhaust pipe located between the first recess and the second recess has an inclined portion that is inclined so that a downstream side is lower than an upstream side. .

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