JP2008240722A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device excellent in diffusion properties and mixing properties of addition agent into exhaust gas. <P>SOLUTION: The exhaust emission control device 1 is provided with an exhaust emission control body 2 in a middle of an exhaust gas channel, and is provided with a mixing chamber 6 and a supply means 7 supplying addition agent B into the mixing chamber 6 in an exhaust gas passage 5 at an upstream side of the exhaust emission control body 2. The mixing chamber 6 is formed out of a diameter expansion part 6a, a diameter contraction part 6b, and an annular wall 6c. A tip part 7a of the supply means 7 is provided to be oriented to at least one of the diameter expansion part 6a and the diameter contraction part 6b for enabling addition agent B to be directly injected to at least one of the diameter expansion part 6a and the diameter contraction part 6b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device mounted on an internal combustion engine such as a diesel engine.

  As an exhaust gas purification device mounted on an internal combustion engine such as a diesel engine, in order to collect particulate matter (particulate matter, hereinafter referred to as PM) contained in the exhaust gas, diesel in the middle of the exhaust pipe Known are those provided with a particulate filter (hereinafter referred to as DPF) and those provided with a NOx reduction catalyst carrier in order to reduce the amount of nitrogen oxide (hereinafter referred to as NOx) contained in the exhaust gas. It has been.

  Conventionally, in order to improve the purification performance of an exhaust gas purification device, an additive is supplied into the exhaust gas. For example, in order to remove PM accumulated in the DPF, a fuel such as light oil is supplied as an additive into the exhaust gas to burn the PM and regenerate the DPF.

  Further, in the NOx reduction catalyst carrier, for example, by supplying an additive such as urea (reducing agent) into the exhaust gas, NOx occluded in the NOx reduction catalyst carrier can be reduced to purify the exhaust gas. Has been done.

  By the way, when the additive is supplied into the exhaust gas as described above, the additive is uniformly mixed and diffused in the exhaust gas, and the additive is evenly distributed to the upstream end face of the DPF or the catalyst carrier. However, it is indispensable for improving the purification performance. For example, in Patent Document 1, a mixing chamber is arranged in the exhaust pipe upstream of the catalyst, and a nozzle for supplying an additive (reducing agent) is arranged in the mixing chamber, and the additive is placed in the mixing chamber. There has been proposed an exhaust gas purifying apparatus that uniformly mixes exhaust gas.

  However, in the exhaust gas purification device described in Patent Document 1, the exhaust gas stays in the mixing chamber, so that the additive is mixed to some extent in the exhaust gas, but a part of the additive is not mixed. There is a risk that the catalyst flows as it is in the center of the upstream end face of the catalyst. Therefore, in Patent Document 2, a step is provided in the exhaust passage to generate a vortex, and an additive (purifier) is injected at or near the step, and a dispersion member (impact plate) provided in the exhaust passage. There has been proposed an exhaust gas purification device that causes an additive to collide with the exhaust gas.

However, when the dispersion member is provided as in the exhaust gas purification device described in Patent Document 2, there are problems that increase in pressure loss, the structure of the exhaust gas purification device is complicated, and the number of parts of the dispersion member increases.
JP-A-5-272331 JP 2006-322327 A

  In view of the above problems, an object of the present invention is to provide an exhaust gas purification device that is excellent in the mixing and diffusibility of additives in exhaust gas.

  In order to solve the above problems, in the first invention, an exhaust gas purifying body is provided in the middle of the exhaust gas flow path, and the mixing chamber and the mixing chamber are provided in the exhaust gas flow path upstream of the exhaust gas purifying body. In the exhaust gas purifying apparatus comprising a supply means for supplying an additive into the chamber, the mixing chamber is formed of a diameter-expanded portion, a diameter-reduced portion, and an annular wall, The tip portion of the supply means is provided so as to be directed to at least one of the diameter-expanded portion and the diameter-reduced portion so that the additive is directly injected to at least one of them.

  In a second invention, in the first invention, at least one of the enlarged diameter portion and the reduced diameter portion is formed substantially orthogonal to the exhaust gas flow path.

  According to a third aspect, in the first or second aspect, the additive is directly injected into at least one upper portion of the enlarged diameter portion and the reduced diameter portion in a state where the exhaust gas purifying device is mounted on a vehicle. As described above, the tip of the supply means is provided so as to face the upper part.

  ADVANTAGE OF THE INVENTION According to this invention, the exhaust-gas purification apparatus which is excellent in the mixing property and diffusibility of the additive in exhaust gas can be provided.

  The best mode for carrying out the present invention will be described below based on the embodiment shown in FIGS.

  FIG. 1 is a configuration diagram showing an exhaust gas purifying apparatus according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a mixing chamber in FIG. The exhaust gas purification device 1 is configured as follows. An exhaust gas purifier 2 such as DPF or NOx reduction catalyst carrier is housed in the casing 4 via a holding member 3 such as a wire mesh or an alumina mat. A tapered cone 4a is formed on the upstream side (left side in the figure) of the casing 4, and a tubular exhaust gas flow path 5 is connected thereto. In the middle of the exhaust gas flow path 5, a mixing chamber 6 having a flow path cross-sectional area larger than that of the exhaust gas flow path 5 is provided in order to mix and diffuse the exhaust gas and the additive.

  The mixing chamber 6 is comprised by the enlarged diameter part 6a, the reduced diameter part 6b, and the annular wall 6c with reference to FIG.1 and FIG.2. Then, the supply nozzle 7 serving as an additive supply means is provided so as to penetrate the annular wall 6c with its tip 7a directed toward the reduced diameter portion 6b so that the additive is directly injected onto the inner wall surface of the reduced diameter portion 6b. Has been. It is desirable that the additive spray that diffuses after injection collides with the inner wall surface of the reduced diameter portion 6b.

  Next, mixing and diffusion of the exhaust gas and the additive in the present embodiment will be described with reference to FIG. When exhaust gas G discharged from an internal combustion engine (not shown) flows into the mixing chamber 6, a vortex A is generated by the enlarged diameter portion 6a. In particular, since the enlarged diameter portion 6a is formed substantially orthogonal to the exhaust gas passage 5, the vortex A is actively generated. On the other hand, the additive B injected from the supply nozzle 7 collides with the reduced diameter portion 6b, and is quickly diffused into the mixing chamber 6 by the collision and reflection. Therefore, in addition to the mixing action by the volume (large volume) of the mixing chamber 6 itself, the additive can be sufficiently mixed and diffused into the exhaust gas by the action of the vortex A and the diffusion action by the collision reflection of the additive B.

  Further, when a liquid fuel such as light oil is used as the additive, the liquid fuel collides with the reduced diameter portion 6a which has become a high temperature due to the heat of the exhaust gas, whereby the vaporization of the liquid fuel is promoted, and the additive is discharged into the exhaust gas Can mix and diffuse well into.

  What is necessary is just to set suitably to which of the expanded diameter part 6a and the reduced diameter part 6b an additive is directly injected. Further, for example, when the temperature of the enlarged diameter portion 6a and the reduced diameter portion 6b is unlikely to become high due to the state of the internal combustion engine or the state of the exhaust gas, and the colliding additive is difficult to vaporize, the exhaust gas purifying device 1 is In the state of being mounted on the vehicle (the vertical direction in FIG. 1 is the same as the vertical direction of the vehicle), for example, as shown in FIG. When the additive B is directly sprayed upward), the additive is mixed into the exhaust gas while dropping downward due to gravity.

  FIG. 3 is a block diagram showing an exhaust gas purifying apparatus according to the second embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 11 includes a porous pipe 8 in which a large number of vent holes 8 a are formed in the exhaust gas flow path 5 between the mixing chamber 6 and the exhaust gas purification body 2. Then, the exhaust gas mixed with the additive in the mixing chamber 6 is further passed through the vent hole 8a of the pipe 8 and diffused, whereby the additive can be further mixed and diffused into the exhaust gas.

  FIG. 4 is a block diagram showing an exhaust gas purification apparatus according to the third embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 21 is provided with an enlarged diameter portion 5a in a part of the exhaust gas flow path 5 between the mixing chamber 6 and the exhaust gas purification body 2, and is larger than the porous pipe 8 in the enlarged diameter portion 5a. A porous pipe 9 having a diameter is provided. Also in this embodiment, the same operational effects as those of the second embodiment can be obtained, and more effective than the second embodiment in that the pressure loss of the exhaust gas is small.

  FIG. 5 is a block diagram showing an exhaust gas purifying apparatus according to a fourth embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along the line CC in FIG. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 31 is provided with a mixer portion 10 in a part of the exhaust gas flow path 5 between the mixing chamber 6 and the exhaust gas purification body 2. Curved current plates 10a and 10b are provided in the mixer section 10. The exhaust gas mixed with the additive in the mixing chamber 6 flows in a meandering manner while colliding with the current-transforming plates 10a and 10b when passing through the mixer section 10, so that the additive is exhausted. More mixing and diffusion into the gas. The shape of the current plate may be a flat plate, and the size, number, and arrangement of the current plates may be set as appropriate.

  FIG. 7 is a configuration diagram showing an exhaust gas purifying apparatus according to a fifth embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 41 is configured such that the enlarged diameter portion 12 a and the reduced diameter portion 12 b of the mixing chamber 12 are inclined with respect to the exhaust gas flow path 5. By appropriately setting the inclination angles of the enlarged diameter portion 12a and the reduced diameter portion 12b, the vortex A described in the first embodiment and the diffusion due to the impact reflection of the additive B are tuned to optimize the mixing and diffusion. Can be achieved. Further, the enlarged diameter portion 12a and the reduced diameter portion 12b may be formed in one mixing chamber by mixing an inclined portion and a portion substantially orthogonal to the exhaust gas passage 5 described in the first embodiment. I do not care.

  FIG. 8 is a block diagram showing an exhaust gas purification apparatus according to the sixth embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 51 is formed by forming the diameter-expanded portion 13a and the diameter-reduced portion 13b of the mixing chamber 13 into a spherical shape.

  FIG. 9 is a block diagram showing an exhaust gas purifying apparatus according to the seventh embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 61 is a unit in which a mixing chamber 15 is integrally provided in a casing 14 that houses an exhaust gas purification carrier 2. The mixing chamber 15 is formed by fixing the reduced diameter member 16 having the reduced diameter portion 16b in the casing 14. Also in this embodiment, the same effect as the first embodiment can be obtained.

  FIG. 10 is a block diagram showing an exhaust gas purifying apparatus according to the eighth embodiment of the present invention. The same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted. The exhaust gas purification device 71 is configured such that an exhaust gas passage 18 connected to the upstream side of the mixing chamber 17 and an exhaust gas passage 19 connected to the downstream side are offset by the amount of OF. Thereby, the flow path length of the exhaust gas passing through the inside of the mixing chamber 17 can be increased, and the additive can be further mixed and diffused into the exhaust gas.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Even if there is a change of the range which does not deviate from the meaning of this invention, it is included in this invention. For example, the mixing chamber may be arranged concentrically, eccentrically, or inclined with respect to the exhaust gas passage. A plurality of supply nozzles may be provided in one mixing chamber. The tip of the supply nozzle may be installed at an arbitrary angle three-dimensionally with respect to the exhaust gas passage. Moreover, the cross-sectional shape orthogonal to the exhaust gas flow path of the mixing chamber is arbitrary, such as a circular cross section such as a perfect circle, an ellipse, or an ellipse, or a polygonal cross section. A plurality of exhaust gas purifiers may be arranged in series in the casing. Any exhaust gas purifier may be employed as long as it purifies exhaust gas by injecting an additive.

1 is a configuration diagram of an exhaust gas purification device according to a first embodiment of the present invention. The perspective view of the mixing chamber of the exhaust-gas purification apparatus which concerns on the 1st Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 2nd Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 3rd Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 4th Embodiment of this invention CC sectional view enlarged on CC line of the exhaust-gas purification apparatus which concerns on the 4th Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 5th Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 6th Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 7th Embodiment of this invention The block diagram of the exhaust-gas purification apparatus which concerns on the 8th Embodiment of this invention

Explanation of symbols

1, 11, 21, 31, 41, 51, 61, 71, 81 Exhaust gas purification device 2 Exhaust gas purification body 5, 18, 19 Exhaust gas flow path 6, 12, 13, 15, 17, 20 Mixing chamber 6a, 12a, 13a, 16a, 17a Expanded diameter part 6b, 12b, 13b, 16b, 17b Reduced diameter part 6c, 12c, 13c, 17c Annular wall 7 Supply nozzle (supply means)
7a Tip section 8,9 Perforated pipe 10 Mixer section

Claims (3)

An exhaust comprising an exhaust gas purifier in the middle of the exhaust gas flow path, and a mixing chamber and supply means for supplying an additive into the mixing chamber in the exhaust gas flow path upstream of the exhaust gas purifier In the gas purification device,
The mixing chamber is formed of an enlarged diameter portion, a reduced diameter portion, and an annular wall, and the tip of the supply means is directly injected to at least one of the enlarged diameter portion and the reduced diameter portion. An exhaust gas purification apparatus characterized in that a portion is provided so as to be directed to at least one of the enlarged diameter portion and the reduced diameter portion.   2. The exhaust gas purification device according to claim 1, wherein at least one of the enlarged diameter portion and the reduced diameter portion is formed substantially orthogonal to the exhaust gas flow path.   In a state where the exhaust gas purifying device is mounted on a vehicle, the tip of the supply means is placed above the upper part so that the additive is directly injected into at least one upper part of the enlarged diameter part and the reduced diameter part. The exhaust gas purifying device according to claim 1 or 2, wherein the exhaust gas purifying device is provided so as to be directed to the section.

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