JP2018135811A - Exhaust purification equipment - Google Patents

Abstract

An exhaust purification device that uniformly supplies a reducing agent to an end face of an exhaust purification catalyst is provided. An exhaust emission control device includes an exhaust pipe, a catalyst for purifying exhaust gas, an addition valve section for adding a reducing agent, and a dispersion section for dispersing a reducing agent injected from the addition valve section. And. The exhaust pipe 20 includes a downstream portion 21 where the catalyst 11 and the dispersion portion 12 are disposed, an upstream portion 22, and a curved portion 23. The addition valve portion 13 protrudes into the bending portion 23 so that the injection opening portion 14 faces the dispersion portion 12. The bending portion 23 has a partition portion 32B extending toward the internal space. In the partition portion 32B, the downstream end portion 32C is directed to the dispersion portion 12, and the injection opening portion 14 is blocked from the upstream portion 22 side. [Selection] Figure 1

Description

  The present invention relates to an exhaust purification device that purifies exhaust gas from an internal combustion engine.

  2. Description of the Related Art An exhaust gas purification apparatus for an internal combustion engine that includes an exhaust pipe provided with a catalyst that purifies exhaust gas and an addition valve that adds a reducing agent to the catalyst is known. In the exhaust emission control device disclosed in Patent Document 1, the exhaust pipe has a downstream direction in which the central axis of the pipe extends in a downstream portion where the catalyst is arranged, and a central axis of the pipe in a portion upstream of the portion where the catalyst is arranged. Is different from the upstream direction. The exhaust pipe is curved at a portion where the downstream direction and the upstream direction intersect with each other, and an addition valve is disposed in the curved curved portion. A dispersion plate is disposed downstream of the exhaust pipe and upstream from the catalyst, and the reducing agent injected from the addition valve is dispersed toward the catalyst by the dispersion plate.

JP 2016-186277 A

  In the exhaust emission control device disclosed in Patent Document 1, the addition valve is fixed to the curved portion of the exhaust pipe so that the injection hole faces the dispersion plate. However, since the curved portion of the exhaust pipe is a portion where the flow of exhaust gas is changed in the exhaust pipe, the exhaust flowing through the curved portion tends to be directed to the wall surface on the curved outer peripheral side. For this reason, depending on the bending mode of the exhaust pipe and the flow rate of the exhaust, the reducing agent injected from the addition valve receives the influence of the exhaust flowing through the bending portion, so that the reducing agent is biased toward a part of the dispersion plate. Therefore, there is a problem that the reducing agent that reaches the end face of the catalyst is difficult to be uniformly dispersed.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
An exhaust emission control device for solving the above problems includes an exhaust pipe that forms an exhaust passage of an internal combustion engine, a catalyst that purifies exhaust, an addition valve portion that adds a reducing agent, and a reduction injected from the addition valve portion. An exhaust purification device comprising a dispersion part for dispersing the agent, wherein the exhaust pipe has a downstream part in which the catalyst is arranged and extends linearly, and an exhaust upstream side of the downstream part. An upstream portion that is linearly extended so as to intersect the extending direction of the downstream portion, and a portion that intersects the extending direction of the downstream portion and the extending direction of the upstream portion The dispersion portion is provided in the downstream portion, and the addition valve portion projects into the bending portion so that the injection opening of the reducing agent faces the dispersion portion. The curved portion extends toward the internal space. It has a partition portion is, the partition switching unit has its downstream end is directed to the dispersion unit, and its gist that intercepts the ejection opening from the upstream side.

  According to the said structure, when the downstream end part of a partition part has faced the dispersion | distribution part, a flow changes so that the exhaust_gas | exhaustion which flowed into the curved part may be guided to a partition part and may go to a dispersion | distribution part. And since the injection opening part of the addition valve part is blocked from the upstream side by the partition part, the reducing agent injected from the addition valve part is forced to be changed by the exhaust gas flowing through the curved part. Less affected. This suppresses the injected reducing agent from flowing toward the wall surface of the exhaust pipe. That is, it is possible to suppress the reducing agent from being biased toward a part of the dispersion portion, and the uniformly dispersed reducing agent can reach the end face of the catalyst.

The figure which shows the cross-section about one Embodiment of an exhaust gas purification apparatus.

Hereinafter, an embodiment of an exhaust emission control device will be described with reference to FIG.
As shown in FIG. 1, an exhaust purification device 10 for an internal combustion engine includes a catalyst 11 that selectively reduces NOx contained in exhaust gas in an exhaust pipe 20. The catalyst 11 is disposed in the downstream portion 21 of the exhaust pipe 20. The downstream portion 21 of the exhaust pipe 20 is disposed so as to be positioned below the vehicle on which the internal combustion engine is mounted. The downstream portion 21 extends in a straight line, and is mounted so that the central axis C1 of the downstream portion 21 is parallel to the horizontal direction.

  In the downstream portion 21 of the exhaust pipe 20, a dispersion portion 12 for dispersing a reducing agent injected from an addition valve 17 described later is disposed on the exhaust upstream side of the catalyst 11. The dispersion part 12 is configured by extending a plurality of strip-like dispersion plates from the inner wall of the exhaust pipe 20 toward the central axis C1.

  The exhaust pipe 20 has an upstream portion 22 extending upstream of the downstream portion 21 so as to intersect with the extending direction of the central axis C <b> 1 in the downstream portion 21. The upstream portion 22 is linearly extended so that the central axis C2 of the upstream portion 22 is inclined downward from the exhaust upstream side to the downstream side.

  In the exhaust pipe 20, a curved portion 23 is provided at a portion where the central axis C1 of the downstream portion 21 and the central axis C2 of the upstream portion 22 intersect. The central axis of the curved portion 23 is curved in an arc shape from the downstream end portion of the upstream portion 22 toward the upstream end portion of the downstream portion 21. A hole 25 is formed in the curved outer peripheral wall 24 of the curved portion 23. The addition valve portion 13 is inserted into the hole 25. The addition valve unit 13 is provided with an addition valve 17 for supplying urea water as a reducing agent to the catalyst 11. The addition valve part 13 has a connection part 15 inserted in the exhaust pipe 20 and a heat radiation part 16 covering the addition valve 17. The heat radiation part 16 is provided with heat radiation fins 16A. The addition valve 17 is fixed to the curved portion 23 of the exhaust pipe 20 via the addition valve portion 13. The injection opening 14 located on the bending portion 23 side in the connection portion 15 of the addition valve portion 13 protrudes into the bending portion 23. The injection hole 17 </ b> A of the addition valve 17 is located at the end of the heat radiating part 16 on the connection part 15 side. The injection hole 17 </ b> A of the addition valve 17 is directed to the dispersion unit 12. The addition valve portion 13 is disposed so that the central axis C3 that is the extending direction of the connecting portion 15 in the addition valve portion 13 coincides with the central axis C1 that is the extending direction of the downstream portion 21.

  In the curved outer peripheral wall 24 of the curved portion 23, a gentle gradient portion 27 is formed on the exhaust upstream side of the hole 25. The gradient of the gentle gradient portion 27 is gentler than the gradient of the central axis C2 with respect to the central axis C1.

  The exhaust pipe 20 includes an inner pipe 30 that partially has a double pipe structure. The inner pipe 30 is disposed from the upstream portion 22 to the curved portion 23 of the exhaust pipe 20. The upper side wall portion 31 on the upper side of the inner tube 30 is in contact with the inner surface of the curved inner peripheral wall 28 along the curved shape of the curved portion 23. The lower side wall portion 32 on the lower side of the inner pipe 30 has an inner wall portion 32A arranged in parallel with the gentle gradient portion 27 at a predetermined interval, and a downstream end portion 32C on the exhaust downstream side of the lower wall portion 32 is a dispersion portion. 12, and a partition portion 32 </ b> B that extends to the exhaust downstream side so as to face 12. The bending portion 23 is provided with a gap 40 defined by the inner wall portion 32 </ b> A and the gentle gradient portion 27. The partition portion 32B blocks the injection opening portion 14 of the addition valve portion 13 from the upstream portion 22 side. That is, the lower wall portion 32 is located closer to the curved inner peripheral wall 28 than the central axis C3 that is the extending direction of the connecting portion 15. The injection opening portion 14 of the addition valve portion 13 is located between the partition portion 32 </ b> B and the curved outer peripheral wall 24.

Next, the effect of the exhaust emission control device 10 according to this embodiment will be described.
In the exhaust emission control device 10, the exhaust pipe 20 includes an inner pipe 30, and the exhaust pipe 20 has a partially double-pipe structure. Further, the downstream end portion 32 </ b> C in the lower wall portion 32 of the inner pipe 30 is directed to the dispersing portion 12 provided in the downstream portion 21 of the exhaust pipe 20. For this reason, the flow of the exhaust gas flowing into the curved portion 23 of the exhaust pipe 20 changes so as to be guided by the partition portion 32 </ b> B of the lower side wall portion 32 toward the dispersion portion 12. The injection direction of the reducing agent injected from the addition valve 17 is changed by the exhaust gas flowing through the curved portion 23 because the injection opening portion 14 of the addition valve portion 13 is blocked from the exhaust upstream side by the partition portion 32B. It becomes difficult to be affected by being forced to. As a result, the reducing agent injected from the addition valve 17 is suppressed from flowing toward the wall surface of the exhaust pipe 20. Furthermore, the central axis C3 that is the extending direction of the connecting portion 15 coincides with the central axis C1 that is the extending direction of the downstream portion 21. For this reason, the reducing agent injected from the addition valve 17 can easily reach the dispersion portion 12 provided in the downstream portion 21. That is, according to the exhaust gas purification apparatus 10, the reducing agent is prevented from being sprayed to a part of the dispersion portion 12, and the uniformly dispersed reducing agent can reach the end face of the catalyst 11.

  Further, the exhaust gas that is guided by the partition portion 32 </ b> B and travels toward the dispersion portion 12 is separated from the lower wall portion 32 on the exhaust downstream side of the downstream end portion 32 </ b> C of the lower wall portion 32. That is, in the exhaust pipe 20, the exhaust gas directed toward the dispersion part 12 is guided to the dispersion part 12 by being guided by the lower wall part 32 of the inner pipe 30, and the curved outer periphery of the bending part 23 facing the lower wall part 32. The wall 24 is not directly involved in changing the direction in which the exhaust flows. Therefore, the flow of exhaust gas hardly occurs in the space between the partition portion 32 </ b> B of the lower wall portion 32 and the curved outer peripheral wall 24. That is, the flow of exhaust gas hardly occurs around the injection opening 14 located between the partition 32B and the curved outer peripheral wall 24. Accordingly, the addition valve 17 is not easily exposed to the flow of exhaust gas, and an increase in the tip temperature of the addition valve 17 due to the heat of the exhaust gas being transmitted to the addition valve 17 can be suppressed. If the tip temperature of the addition valve 17 rises excessively, deposits derived from the reducing agent may be deposited around the injection hole 17A, but the exhaust purification device 10 can suppress the rise in the tip temperature of the addition valve 17. According to this, it is possible to suppress deposits from being accumulated at the tip of the addition valve 17.

  Furthermore, since the partition portion 32B that guides the exhaust blocks the injection opening portion 14 of the addition valve portion 13 only from the upstream portion 22 side, a space from the injection opening portion 14 to the dispersion portion 12 is secured. As a result, the reducing agent injected toward the dispersion part 12 adheres to, for example, the partition wall 32B and the wall surface of the exhaust pipe 20, while making it difficult for the injected reducing agent to be affected by the flow of the exhaust gas. Can be suppressed.

  In the exhaust gas purification apparatus 10, the exhaust gas flowing on the curved outer peripheral side of the exhaust gas flowing into the curved portion 23 collides with the inner wall portion 32 </ b> A in the lower wall portion 32 of the inner tube 30 and changes the flow direction. Since a gap 40 is formed between the inner wall portion 32 </ b> A of the lower wall portion 32 and the gentle gradient portion 27 of the curved outer peripheral wall 24, heat hardly moves from the inner wall portion 32 </ b> A to the gentle gradient portion 27. That is, the amount of heat of the exhaust is prevented from moving outside the exhaust pipe 20. As a result, it is possible to suppress the temperature of the exhaust gas flowing into the catalyst 11 provided in the downstream portion 21 from being lowered. For example, for early activation of the catalyst 11 when the internal combustion engine including the exhaust purification device 10 is started. Can contribute.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, a dispersion plate is illustrated as the dispersion unit 12. The dispersion unit 12 may have a configuration capable of dispersing the reducing agent supplied to the catalyst 11. For example, a grid-like plate provided over the entire passage section in the exhaust pipe 20 can also be employed.

  The provision of the gap 40 between the inner wall portion 32A of the lower wall portion 32 and the gentle slope portion 27 of the curved outer peripheral wall 24 is not an essential configuration. If the lower wall portion 32 and the exhaust pipe 20 form a double structure, it is possible to suppress the amount of heat of the exhaust from moving to the outside of the exhaust pipe 20.

  -The central axis C1 of the downstream part 21 and the central axis C3 of the connection part 15 do not necessarily need to correspond. The injection hole 17 </ b> A of the addition valve 17 provided in the addition valve portion 13 only needs to be directed to the dispersion portion 12.

  In the above embodiment, the partition portion 32B is formed by disposing the inner tube 30 and partially forming the exhaust tube 20 in a double tube structure. Other configurations may be employed as the partition portion 32B that blocks the injection opening 14 from the upstream portion 22 side. For example, a flat plate extending from the gentle gradient portion 27 toward the dispersion portion 12 may be provided to form the partition portion 32B.

  DESCRIPTION OF SYMBOLS 10 ... Exhaust gas purification device, 11 ... Catalyst, 12 ... Dispersion part, 13 ... Addition valve part, 14 ... Injection opening part, 15 ... Connection part, 16 ... Radiation part, 16A ... Radiation fin, 17 ... Addition valve, 17A ... Injection Hole, 20 ... exhaust pipe, 21 ... downstream part, 22 ... upstream part, 23 ... curved part, 24 ... curved outer peripheral wall, 25 ... hole, 27 ... gentle gradient part, 28 ... curved inner peripheral wall, 30 ... inner pipe, 31 ... upper wall part, 32 ... lower wall part, 32A ... inner wall part, 32B ... partition part, 32C ... downstream end part, 40 ... gap, C1 ... central axis, C2 ... central axis, C3 ... central axis.

Claims (1)

Exhaust gas purification comprising an exhaust pipe that forms an exhaust passage of an internal combustion engine, a catalyst that purifies exhaust gas, an addition valve portion that adds a reducing agent, and a dispersion portion that disperses the reducing agent injected from the addition valve portion A device,
The exhaust pipe extends linearly so that the downstream side where the catalyst is disposed and extends linearly and the upstream side of the downstream part and the direction of extension of the downstream part intersect. An upstream portion, and a curved portion curved in an arc shape at a portion where the extending direction of the downstream portion and the extending direction of the upstream portion intersect,
The dispersion part is provided in the downstream part,
The addition valve portion is provided so as to protrude into the bending portion so that the injection opening of the reducing agent faces the dispersion portion,
The curved portion has a partition portion extending toward the internal space, and the partition portion has a downstream end directed to the dispersion portion, and the injection opening from the upstream portion side. Exhaust gas purification device that blocks parts.

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