JP2019157826A - Exhaust emission control device of internal combustion engine and pipe member applied to the device - Google Patents

Abstract

To provide an exhaust emission control device of an internal combustion engine in which exhaust resistance is reduced and furthermore the corrosion of an exhaust pipe resulting from collected urea water (reductant) can be suppressed.SOLUTION: The exhaust emission control device of an internal combustion engine comprises: an exhaust pipe 1; an injection valve 2 injecting urea water (reductant) into the exhaust pipe 1; a selective reduction-type NOx catalyst 3 provided in the exhaust pipe 1 located at a downstream side of the injection valve 2; a pipe member 10 forming a part of the exhaust pipe 1 in a position between the injection valve 2 and the NOx catalyst 3, and extending in a horizontal direction; and a dispersion plate 50 provided in the pipe member 10, extending in a horizontal direction, and dispersing a collected reductant.SELECTED DRAWING: Figure 1

Description

  The present disclosure mainly relates to an exhaust emission control device for an internal combustion engine including a selective reduction type NOx catalyst.

  As an exhaust gas purification apparatus for an internal combustion engine, an injection valve that injects urea water (reducing agent) into an exhaust pipe, and a selective reduction type that reduces and purifies nitrogen oxide (NOx) in exhaust gas by ammonia generated from urea water. There is an exhaust purification device equipped with a NOx catalyst.

JP 2014-084850 A

  In the above exhaust purification device, a portion of the urea water injected from the injection valve adheres in a liquid phase state to the lower surface portion of the exhaust pipe located between the injection valve and the NOx catalyst, resulting in a urea water pool. There is a case. In this case, the exhaust pipe may corrode due to urea water pool.

  For this, a technique is known in which urea water injected from an injection valve is stirred and mixed with exhaust gas by a mixer device provided in the exhaust pipe to promote hydrolysis and suppress generation of urea water pool. However, in this method, the exhaust resistance is increased by the mixer device.

  Therefore, the present disclosure has been created in view of such circumstances, and the object thereof is applied to an exhaust purification device for an internal combustion engine that can suppress exhaust pipe corrosion caused by urea water pool while suppressing exhaust resistance, and the device. It is to provide a pipe member.

  An exhaust gas purification apparatus for an internal combustion engine according to the present disclosure includes an exhaust pipe through which exhaust gas from the internal combustion engine is circulated, an injection valve that injects a reducing agent into the exhaust pipe, and an exhaust pipe that is located downstream of the injection valve. A selective reduction type NOx catalyst that is provided and purifies nitrogen oxides in exhaust using the reducing agent, and forms a part of the exhaust pipe at a position between the injection valve and the NOx catalyst; And a dispersion plate that is provided inside the tube member and extends in the horizontal direction to disperse the reducing agent reservoir.

  Moreover, it is preferable that at least one side portion of the dispersion plate is fixed to the inner peripheral surface of the pipe member and bent upward.

  The pipe member has an inlet below or above the upstream end thereof, and the injection valve injects the reducing agent from the position of the upstream end in the axial direction of the pipe member toward the downstream side. Preferably, a plurality of the dispersion plates are provided at intervals in the vertical direction, and the plurality of dispersion plates are unevenly distributed on the opposite side of the upper side or the lower side where the inlets are present.

  In addition, it is preferable that the upstream end of the dispersion plate located above or below where the inlet exists is located upstream from the upstream end of the dispersion plate located on the opposite side above or below where the inlet exists.

  Moreover, it is preferable that the said pipe member can be divided | segmented from the remainder of the said exhaust pipe.

  In addition, a pipe member according to the present disclosure is provided in an exhaust pipe through which exhaust gas from an internal combustion engine is circulated, an injection valve that injects a reducing agent into the exhaust pipe, and an exhaust pipe that is located downstream of the injection valve. A selective reduction type NOx catalyst that purifies nitrogen oxides in exhaust gas using the reducing agent, and a pipe member that is applied to an exhaust gas purification device for an internal combustion engine, the injection valve, the NOx catalyst, A part of the exhaust pipe at a position between the two is formed, and is provided with a dispersion plate disposed in the horizontal direction and extending in the horizontal direction for dispersing the reducing agent reservoir.

  According to the exhaust purification device for an internal combustion engine and the pipe member applied to the device according to the present disclosure, corrosion of the exhaust pipe caused by urea water (reducing agent) pool can be suppressed while suppressing exhaust resistance. .

1 is a schematic configuration diagram illustrating an entire exhaust gas purification apparatus for an internal combustion engine. FIG. 2 is an enlarged longitudinal sectional view of a pipe member and a dispersion plate shown in FIG. It is III-III sectional drawing of FIG. It is an expansion longitudinal cross-sectional view of the pipe member and dispersion plate which concern on a 1st modification. It is a longitudinal cross-sectional view of the joint pipe | tube shown in FIG. It is a schematic block diagram which shows the whole exhaust gas purification apparatus which concerns on a 2nd modification. FIG. 7 is an enlarged longitudinal sectional view of the pipe member and the dispersion plate shown in FIG. 6. It is an expansion longitudinal cross-sectional view of the pipe member and dispersion plate which concern on a 3rd modification.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiment, 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) equipped with an exhaust purification device. However, these directions are merely determined for convenience of explanation. In the present embodiment, the “horizontal direction” means the horizontal direction when the exhaust purification device is mounted and used in a vehicle.

  FIG. 1 is a schematic front view showing the entire exhaust emission control device 100. In the figure, the white arrow A indicates the flow of exhaust gas in the exhaust pipe 1, and the dotted arrow B indicates the flow of urea water injected from the injection valve 2.

  As shown in FIG. 1, an exhaust purification device 100 includes an exhaust pipe 1 through which exhaust gas from an internal combustion engine (not shown) is circulated, an injection valve 2 that injects urea water (reducing agent) into the exhaust pipe 1, and an injection And a NOx catalyst 3 provided in the exhaust pipe 1 located on the downstream side of the valve 2.

  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 NOx catalyst 3 is a selective reduction type NOx catalyst that purifies nitrogen oxide (NOx) in the exhaust gas using ammonia (NH ₃ ) generated by hydrolysis of urea water as a reducing agent.

  Further, the exhaust purification device 100 includes a first mixing pipe 10 as a pipe member that forms a part of the exhaust pipe 1 at a position between the injection valve 2 and the NOx catalyst 3 and extends in the horizontal direction. The exhaust purification device 100 includes a dispersion plate 50 that is provided inside the first mixing pipe 10 and extends in the horizontal direction to disperse the urea water pool P (see FIG. 3).

  Specifically, the exhaust pipe 1 includes a first mixing pipe 10, a second mixing pipe 20, and a catalyst casing 30 that are sequentially connected from the upstream side at a position between the injection valve 2 and the NOx catalyst 3. Further, the exhaust pipe 1 has an exhaust introduction pipe 40 connected to the upstream end of the first mixing pipe 10 at a position upstream of the injection valve 2. The mixing pipes 10, 20, the catalyst casing 30, and the exhaust introduction pipe 40 are made of a stainless material that is resistant to urea corrosion.

The mixing tubes 10 and 20 have a function of mixing urea water injected from the injection valve 2 with exhaust gas and hydrolyzing it into ammonia by exhaust heat. The catalyst casing 30 contains the NOx catalyst 3 and the ammonia oxidation catalyst 4 from the upstream side. The ammonia oxidation catalyst 4 is an oxidation catalyst that oxidizes surplus ammonia (NH ₃ ) that has not been consumed in the reduction of NOx by the NOx catalyst 3 to generate N ₂ .

  In the present embodiment, the first mixing pipe 10 extends in the horizontal direction from the upstream end toward the downstream end, and the second mixing pipe 20 is bent upward from the position of the downstream end of the first mixing pipe 10. It is folded in a U shape. Further, the catalyst casing 30 extends leftward in the horizontal direction from the position of the downstream end of the second mixing pipe 20. On the other hand, the exhaust introduction pipe 40 has a downstream end that extends upward toward the upstream end of the first mixing pipe 10.

  FIG. 2 is an enlarged longitudinal sectional view showing the first mixing tube 10 and the dispersion plate 50, and FIG. 3 is a sectional view taken along the line III-III in FIG. In the figure, the symbol X indicates the central axis (tube axis) of the first mixing pipe 10 extending rightward in the horizontal direction. In the present embodiment, the axial upstream side of the first mixing tube 10 is the left side, and the axial downstream side is the right side.

  As shown in FIG. 2, the first mixing tube 10 has an inlet 10 in below the upstream end portion (the left end portion in the figure). Moreover, the 1st mixing pipe 10 has the exit 10out in the downstream edge part (illustration, right side edge part).

  Specifically, the first mixing tube 10 forms the inlet 10 in by bending the upstream end portion downward by 90 °. A left end wall portion 11 extending in the vertical direction is formed at the upstream end in the axial direction of the first mixing tube 10.

  The inlet 10in of the first mixing pipe 10 is flange-connected to the outlet 40out of the exhaust introduction pipe 40 using bolts and nuts (not shown). Further, the outlet 10out of the first mixing tube 10 is flange-connected to the inlet 20in of the second mixing tube 20 using bolts and nuts (not shown). That is, the first mixing pipe 10 of the present embodiment is configured to be separable from the remaining part of the exhaust pipe 1 (here, the second mixing pipe 20 and the exhaust introduction pipe 40). However, the first mixing pipe 10 may be formed integrally with the second mixing pipe 20 and the exhaust introduction pipe 40 by welding or the like.

  The injection valve 2 is provided so as to inject urea water from the position of the upstream end in the axial direction of the first mixing pipe 10 toward the downstream side. Specifically, the injection valve 2 is inserted and attached to an attachment hole 12 formed so as to penetrate the left end wall portion 11, and injects urea water coaxially with the tube axis X of the first mixing tube 10. As shown by arrows A and B, the urea water injected from the injection valve 2 is introduced into the first mixing pipe 10 from the inlet 10in and pushed by the exhaust gas that turns to the right, and the upper corner on the out corner side. Tend to drift.

  A plurality of dispersion plates 50 are provided at intervals in the vertical direction. Specifically, three dispersion plates 50 are provided at equal intervals in parallel with the tube axis X. However, the respective dispersion plates 50 may not be arranged at equal intervals. Further, the number of the dispersion plates 50 may be any number, and may be one, two, or four or more.

  Further, the dispersion plate 50 is made of a stainless material resistant to urea corrosion, and is formed in a thin flat plate shape having a thickness of about 1 mm, for example. However, the dispersion plate 50 may be made of any material and thickness.

  Further, the respective dispersion plates 50 are arranged at a distance from the left side wall portion 11. That is, in the first mixing tube 10, the space between each dispersion plate 50 and the left side wall portion 11 does not hinder the flow of exhaust gas introduced from the inlet 10in, and the introduced exhaust gas is directed to the right in the horizontal direction. A flow path for smooth bending is defined.

  On the other hand, as shown in FIG. 3, the side portions 51 and 52 of each dispersion plate 50 are fixed to the inner peripheral surface 13 of the first mixing tube 10 and are bent upward.

  More specifically, the front side portion 51 and the rear side portion 52 of each dispersion plate 50 are formed to be curved upward with respect to the horizontal direction and welded to the inner peripheral surface 13. However, it is sufficient that at least one of the side portions 51 and 52 of the dispersion plate 50 is fixed to the inner peripheral surface 13. Moreover, the cross-sectional shape of the side parts 51 and 52 may be arbitrary, for example, an angular bent shape or a straight shape extending in the horizontal direction without being bent may be used.

  Further, the respective dispersion plates 50 are arranged so as to be unevenly distributed on the opposite lower side where the inlet 10 in of the first mixing pipe 10 exists, that is, on the upper side. Here, “upwardly distributed” means that the height centers of the plurality of dispersion plates 50 are located above the tube axis X. Further, when there is one dispersion plate 50, it means that the dispersion plate 50 is located above the tube axis X.

  More specifically, each dispersion plate 50 is arranged so that urea water pushed upward by the exhaust gas and drifted upward is uniformly attached to the upper surface of each dispersion plate 50 to generate a uniform urea water pool P.

  In addition, as shown in FIG. 2, the upstream end 50a of the dispersion plate 50 located below where the inlet 10in exists is opposite to the lower side where the inlet 10in exists, that is, upstream from the upstream end 50a of the dispersion plate 50 located above. Located in. More specifically, the position of the upstream end 50a of each dispersion plate 50 is arranged so as to be positioned on the left side in the horizontal direction, that is, on the upstream side, from the upper stage toward the lower stage. This is to make it easier for the lower dispersion plate 50 to accept the urea water than the upper dispersion plate 50 with respect to the urea water that is pushed by the exhaust gas and drifts upward.

  On the other hand, the downstream end 50b of each dispersion plate 50 is disposed downstream of the position of the outlet 10out of the first mixing tube 10. However, the position of the downstream end 50b may be arbitrary, and may be the same position as the outlet 10out, for example. Further, the position of the downstream end 50 b may be changed for each dispersion plate 50.

  Next, based on FIGS. 1-3, the effect of the exhaust gas purification apparatus 100 and the 1st mixing pipe 10 which concern on this embodiment is demonstrated.

  As shown in FIG. 1, the exhaust gas of the internal combustion engine is released to the atmosphere through the exhaust pipe 1. The injection valve 2 injects urea water into the first mixing pipe 10 from the upstream end of the first mixing pipe 10 toward the right side in the horizontal direction. The injected urea water is mixed with the exhaust gas and flows through the first mixing pipe 10 in the right direction. Thereafter, the exhaust gas mixed with the urea water flows into the catalyst casing 30 through the second mixing pipe 20. In this process, the urea water injected from the injection valve 2 is mixed with the exhaust gas and evaporated while being hydrolyzed to produce ammonia.

  In the catalyst casing 30, the exhaust gas containing ammonia passes through the NOx catalyst 3. At this time, the NOx catalyst 3 reduces and purifies NOx with ammonia generated by hydrolysis of urea water. In addition, surplus ammonia that has not been consumed in the reduction of NOx by the NOx catalyst 3 is oxidized in contact with the ammonia oxidation catalyst 4, and release to the atmosphere is suppressed.

  Here, there is a possibility that part of the urea water injected from the injection valve 2 adheres to the lower surface portion of the first mixing tube 10 and remains in the liquid phase state.

Although not shown, if a dispersion plate is not provided in the first mixing tube, the first mixing tube may be corroded due to urea water accumulated on the lower surface of the first mixing tube. More specifically, in this urea water pool, the concentration of ammonium carbamate (NH ₂ COONH ₄ ) and the like contained in the urea water rises and corrodes the first mixing tube in the process of repeated evaporation and supply of the urea water. there is a possibility. Further, when the urea water pool occurs, a white deposit containing a high concentration of NH ₂ COONH ₄ is generated, and this white deposit may cause the first mixing tube to be blocked and corroded.

  With respect to this problem, by providing a mixer device (not shown) in the exhaust pipe, the urea water injected from the injection valve 2 is stirred and mixed with the exhaust to promote hydrolysis and suppress the generation of urea water pool. Techniques are known. However, with this technique, the mixer device increases exhaust resistance and pressure loss in the exhaust pipe, causing problems such as disadvantageous fuel consumption of the internal combustion engine. Moreover, there is a possibility that the mixer apparatus is clogged and corroded by the white deposit.

  Therefore, in the present embodiment, as shown in FIGS. 2 and 3, urea generated in the first mixing tube 10 is provided by providing a dispersion plate 50 extending in the horizontal direction in the first mixing tube 10 extending in the horizontal direction. The water pool P is dispersed in the plurality of dispersion plates 50 and the lower surface portion of the first mixing tube 10.

  Thereby, the area which urea water adheres and accumulates with a liquid phase state increases, the quantity of the water which accumulates in one place can be reduced, and the vaporization evaporation can be promoted. Further, since each dispersion plate 50 extends in the axial direction of the first mixing tube 10, exhaust resistance when exhaust passes through the first mixing tube 10 can be suppressed. As a result, it is possible to suppress the corrosion of the exhaust pipe 1 due to the urea water pool while suppressing the exhaust resistance. In addition, the exhaust pipe 1 can be prevented from being blocked and corroded by white deposits.

  Further, as shown in FIG. 3, the side portions 51 and 52 of the dispersion plate 50 are fixed to the inner peripheral surface 13 of the first mixing tube 10 and are bent upward. Therefore, for example, the accumulated urea water can be prevented from coming into contact with the welded portions between the side portions 51 and 52 of the dispersion plate 50 and the inner peripheral surface 13. As a result, the occurrence of corrosion at the welded portion between the side portions 51 and 52 and the inner peripheral surface 13 can be suppressed.

  Further, the respective dispersion plates 50 are arranged so as to be unevenly distributed upward. Therefore, each of the dispersion plates 50 can evenly accumulate the urea water that has been pushed by the exhaust gas and drifted upward, on the upper surface of each of the dispersion plates 50.

  In addition, as shown in FIG. 2, the upstream end 50 a of the dispersion plate 50 positioned below is positioned upstream of the upstream end 50 a of the dispersion plate 50 positioned above. As a result, the lower dispersion plate 50 can more easily receive the urea water than the upper dispersion plate 50 with respect to the urea water that is pushed by the exhaust gas and drifts upward. As a result, the urea water pool P (see FIG. 3) can be evenly generated on the upper surface of each dispersion plate 50.

  The first mixing pipe 10 is configured to be splittable from the remaining part of the exhaust pipe 1 (here, the second mixing pipe 20 and the exhaust introduction pipe 40). Therefore, when the dispersion plate 50 or the first mixing tube 10 is corroded, it can be easily replaced.

  It should be noted that the present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

  Although not shown, for example, the first mixing tube may have an inlet at the upper side rather than below the upstream end portion. In this case, it is preferable that the respective dispersion plates are arranged so as to be unevenly distributed on the opposite side, that is, on the lower side where the inlet exists. Further, in this case, it is preferable that the upstream end of the dispersion plate located above is located upstream from the upstream end of the dispersion plate located below.

  In addition, although not shown, the inlet of the first mixing tube is not limited to the upper side or the lower side, but may be in any direction such as the side (front or rear). Moreover, each dispersion plate may be arrange | positioned in arbitrary positions in the up-down direction and axial direction of a 1st mixing pipe.

  Further, the above-described embodiment can be modified as follows. In the following description, the same reference numerals are used for the same components as in the basic embodiment described above, and detailed descriptions thereof are omitted.

(First modification)
FIG. 4 is a longitudinal sectional view showing a pipe joint 60 as a pipe member according to a first modification. FIG. 5 is a longitudinal sectional view showing a state where the pipe joint 60 is divided from the first mixing pipe 10 and the second mixing pipe 20.

  In the above-described embodiment, the first mixing pipe 10 has been described as a pipe member. On the other hand, in the first modification, as shown in FIG. 4, a pipe member is constituted by the first mixing pipe 10 and a pipe joint 60 that can be divided from the first mixing pipe 10. Moreover, as shown in FIG. 5, you may interpret only the pipe joint 60 except the 1st mixing pipe 10 as a pipe member.

  Specifically, as shown in FIG. 4, the exhaust pipe 1 of the first modification has a pipe joint 60 that is interposed between the first mixing pipe 10 and the second mixing pipe 20 and connects them. .

  The pipe joint 60 is flange-connected to the outlet 10out of the first mixing pipe 10 and the inlet 20in of the second mixing pipe 20 using bolts and nuts (not shown). Further, the pipe joint 60 includes a dispersion plate 50 so as to protrude leftward in the horizontal direction from the inside of the pipe joint 60.

  Although not shown, at least one side portion of the dispersion plate 50 is fixed to the inner peripheral surface of the pipe joint 60, not the inner peripheral surface of the first mixing pipe 10, and is bent upward. Further, when the pipe joint 60 and the first mixing pipe 10 are flange-connected, the dispersion plate 50 protruding leftward in the horizontal direction is inserted into the inside from the outlet 10out of the first mixing pipe 10.

  According to the first modified example, when the dispersion plate 50 is corroded, it is sufficient to replace the pipe joint 60, and it is not necessary to replace the first mixing pipe 10 itself, so that the cost of replacement parts can be suppressed.

(Second modification)
FIG. 6 is a schematic front view showing the entire second modification, and FIG. 7 is an enlarged longitudinal sectional view showing a mixing tube 70 and a dispersion plate 50 as tube members.

  In the above-described embodiment, the mixing pipes 10 and 20 and the exhaust introduction pipe 40 are bent as a whole. On the other hand, in the second modification, as shown in FIG. 6, the mixing pipe 70 and the exhaust introduction pipe 80 are formed to extend linearly in the horizontal direction.

  The dispersion plate 50 is provided inside the mixing tube 70 and extends in the horizontal direction. Further, the injection valve 2 is provided so as to inject urea water into the mixing pipe 70 obliquely downward from the upper surface of the upstream end portion of the mixing pipe 70.

  Further, as shown in FIG. 7, each dispersion plate 50 is unevenly distributed below the mixing tube 70. Further, the upstream end 50a of the dispersion plate 50 positioned below is positioned upstream of the upstream end 50a of the dispersion plate 50 positioned above. According to this arrangement, the urea water that is jetted obliquely downward and flows downstream while flowing downstream can be evenly adhered to the upper surface of each dispersion plate 50, thereby generating a uniform urea water pool.

(Third Modification)
FIG. 8 is an enlarged longitudinal sectional view showing the first mixing tube 90 and the dispersion plate 50 as tube members according to the third modification.

  In the above-described embodiment, the first mixing tube 10 having the upstream end bent is described as the mixing tube extending in the horizontal direction. On the other hand, as shown in FIG. 8, the first mixing pipe 90 is composed of a pipe main body 90a extending linearly in the horizontal direction and a separate inlet pipe 90b connected to the upstream end of the pipe main body 90a. May be configured. In the illustrated example, the inlet pipe 90b is connected to the lower surface side located downstream of the upstream end in the axial direction of the pipe main body 90a, but this connection position may be arbitrary.

DESCRIPTION OF SYMBOLS 1 Exhaust pipe 2 Injection valve 3 Selective reduction type NOx catalyst 4 Ammonia oxidation catalyst 10 1st mixing pipe (pipe member)
20 second mixing pipe 30 catalyst casing 40 exhaust introduction pipe 50 dispersion plate 100 exhaust purification device

Claims (6)

An exhaust pipe through which the exhaust of the internal combustion engine is circulated;
An injection valve for injecting a reducing agent into the exhaust pipe;
A selective reduction type NOx catalyst provided in the exhaust pipe located downstream of the injection valve and purifying nitrogen oxides in the exhaust gas using the reducing agent;
A pipe member that forms part of the exhaust pipe at a position between the injection valve and the NOx catalyst and extends in a horizontal direction;
An exhaust purification device for an internal combustion engine, comprising: a dispersion plate that is provided inside the pipe member and extends in the horizontal direction to disperse the reducing agent reservoir. The exhaust emission control device for an internal combustion engine according to claim 1, wherein at least one side portion of the dispersion plate is fixed to an inner peripheral surface of the pipe member and is bent upward. The pipe member has an inlet below or above its upstream end,
The injection valve is provided to inject the reducing agent from the position of the upstream end in the axial direction of the pipe member toward the downstream side,
A plurality of the dispersion plates are provided at intervals in the vertical direction,
The exhaust emission control device for an internal combustion engine according to claim 1 or 2, wherein the plurality of dispersion plates are unevenly distributed on the upper side or the lower side opposite to the inlet. The internal combustion engine according to claim 3, wherein an upstream end of the dispersion plate located above or below where the inlet exists is located upstream from an upstream end of the dispersion plate located on the opposite side above or below where the inlet exists. Engine exhaust purification system. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the pipe member can be divided from a remaining portion of the exhaust pipe. An exhaust pipe through which the exhaust gas of the internal combustion engine is circulated, an injection valve that injects a reducing agent into the exhaust pipe, and an exhaust pipe that is located on the downstream side of the injection valve. A selective reduction type NOx catalyst for purifying nitrogen oxides, and a pipe member applied to an exhaust gas purification apparatus for an internal combustion engine,
Forming a part of the exhaust pipe at a position between the injection valve and the NOx catalyst, and extending in the horizontal direction;
A pipe member comprising a dispersion plate for extending a horizontal direction to disperse a reducing agent reservoir.

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