JP5534208B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly to a structure for making the flow of exhaust gas uniform in an exhaust pipe.

Conventionally, diesel exhaust catalysts, NOx occlusion reduction catalysts, urea reduction SCR devices, and diesel particulate filters (hereinafter referred to as DPFs) have been used as exhaust aftertreatment devices for purifying exhaust from diesel engines.
As an example, a flat carrier having a corrugated plate welded to a flat plate is wound to produce a catalyst carrier, and a louver is formed in advance by pressing the flat plate of the catalyst carrier so as to protrude in the center direction. A metal catalyst carrier for purifying exhaust gas that can cause turbulent flow in passing exhaust gas and accelerate the activity of the catalyst has been developed (Patent Document 1).

JP-A-7-293232

As described above, in the exhaust gas-purifying metal catalyst carrier of Patent Document 1, a louver is formed on the catalyst carrier to generate turbulent flow in the catalyst carrier so that the exhaust in the exhaust pipe is made uniform.
However, the flow rate of exhaust gas in the exhaust pipe becomes slower as it approaches the wall surface due to frictional resistance with the inner wall of the exhaust pipe, and the flow rate of exhaust gas increases at the center of the exhaust pipe. Therefore, if the flow rate of exhaust that can pass through the louver is small relative to the flow rate of exhaust in the center, exhaust cannot sufficiently flow into the outer periphery, and the flow of exhaust cannot be made uniform between the center and the outer periphery. It becomes.

  Therefore, when the exhaust gas-purifying metal catalyst carrier of Patent Document 1 is used in, for example, a DPF, the trapped and deposited particulate matter (hereinafter referred to as PM) is combusted by a high-temperature oxidizing atmosphere gas flowing into the DPF. In the forced regeneration to be removed, the temperature of the DPF outer peripheral portion decreases relative to the central portion by reducing the temperature of the high-temperature oxidizing atmosphere gas flowing into the DPF outer peripheral portion relative to the DPF central portion. It is not completely removed, which causes clogging of the DPF and is not preferable.

Further, in the urea reduction type SCR device, the reducing agent (urea) flowing into the catalyst in the device becomes non-uniform in the catalyst, so that the reducing agent does not reach the entire catalyst and the NOx reduction performance is lowered. It is not preferable.
The present invention has been made to solve such a problem, and an object of the present invention is an internal combustion engine that can make the flow of exhaust gas uniform in the exhaust passage and improve exhaust gas purification performance. An object of the present invention is to provide an exhaust emission control device for an engine.

In order to achieve the above object, an exhaust purification device for an internal combustion engine according to claim 1 is provided in an exhaust passage of the internal combustion engine, and is provided in an exhaust purification means for purifying exhaust, and in the exhaust passage upstream of the exhaust purification means. A plurality of exhaust rectification passages extending in the exhaust flow direction of the exhaust passage, and exhaust guide means for guiding the exhaust from a central portion of the exhaust passage to an outer peripheral portion. Is provided with a plurality of induction parts for inducing exhaust from the exhaust rectification path on the center side to the exhaust rectification path outside through an opening provided in a side wall that divides the exhaust rectification path, are arranged such that the opening faces the product of the opening per unit area as the toward the outer peripheral portion from the central portion of the exhaust passage is increased, the exhaust guide means, in the downstream of the predetermined distance after the upstream end of the exhaust flow direction, downstream It said guide portion is formed to decrease in the order from the central portion of the exhaust passage toward the direction, characterized in Rukoto.

Also, in the exhaust purification system of an internal combustion engine according to claim 2, Oite to claim 1, wherein the inductive section, so that the part of the side wall partitioning the discharge rectifying path protrudes toward the center of the exhaust passage And a leading portion that opens and forms an upstream side of the cut and raised portion in the exhaust flow direction.

According to a third aspect of the present invention, there is provided an exhaust gas purification apparatus for an internal combustion engine according to the second aspect , wherein the exhaust guiding means is formed by laminating a flat plate and a corrugated plate, and winding the superposed flat plate and the corrugated plate into a layered form. The exhaust rectification path is formed between the flat plate and the corrugated plate, and the opening is provided at least in the flat plate.
According to a fourth aspect of the present invention, there is provided the exhaust gas purification apparatus for an internal combustion engine according to the third aspect , wherein the cut-and-raised portion is provided on the flat plate, and the opening is formed along with the formation of the cut-and-raised portion. Features.

Further, in the exhaust emission control device for an internal combustion engine according to claim 5 , in any one of claims 1 to 4 , the guide portion has an opening area of the opening portion larger than an opening area of the introduction portion. Features.
Further, in the exhaust emission control device for an internal combustion engine according to claim 6 , in any one of claims 1 to 5 , the exhaust induction means has a lower thermal conductivity from the central portion of the exhaust passage toward the outer peripheral portion, Further, the heat capacity is increased.

The exhaust gas purification apparatus for an internal combustion engine according to claim 7 is characterized in that, in any one of claims 1 to 6 , the exhaust induction means is coated with a ceramic coating agent on an outermost peripheral portion.

According to the first aspect of the present invention, a plurality of exhaust rectification passages extending in the exhaust circulation direction of the exhaust passage are formed upstream of the exhaust purification means, and the center side is provided via the opening provided in the side wall defining the exhaust rectification passage. an exhaust guide means that induction portion is a plurality of inducing exhaust on the outside of the exhaust rectifying passage is provided from the exhaust commutation paths, open surface product per unit area as the induction portion toward the peripheral portion from the central portion of the exhaust passage Is arranged to be large.

Accordingly, the exhaust at the center of the exhaust passage having a high flow velocity can be guided to the outer periphery of the exhaust passage by the guide portion provided in the exhaust rectification passage.
Therefore, since the exhaust flow can be made uniform in the exhaust passage, exhaust purification performance can be improved.
Further, in the downstream from the upstream end of the predetermined distance after the exhaust guide means induction unit, forms a so that to decrease from the center portion of the exhaust passage toward the downstream direction in the order, the exhaust downstream part, the downstream part Even if the guiding part is formed, exhaust cannot be directed toward the outer peripheral part, and forming an unnecessary guiding part hinders the flow of exhaust, so the pressure loss is reduced by gradually reducing the guiding part. can do.

According to the second aspect of the present invention, the cut-and-raised part and the cut-and-raised part in the exhaust flow direction are such that a part of the side wall defining the exhaust rectification path in the guide part protrudes toward the center part of the exhaust passage. And an introduction part that opens and forms the upstream side, and the exhaust flowing through the exhaust induction passage can be efficiently guided to the outer periphery of the exhaust passage, so that the exhaust flow is made uniform in the exhaust passage. Therefore, exhaust purification performance can be improved.

According to a third aspect of the present invention, the exhaust guide means is formed by laminating a flat plate and a corrugated plate in a layered manner, and is open to a flat plate that divides the central exhaust rectification path and the outer peripheral exhaust rectification path. Since the portion is provided, the exhaust at the center of the exhaust passage can be guided to the outer periphery of the exhaust passage. Further, even if the corrugated crest is wound around the outer periphery of the flat plate opening, the corrugated crest is in contact with the opening in a planar manner, so that the exhaust can be guided without being blocked. it can.

According to the invention of claim 4 , the opening is formed along with the formation of the cut-and-raised portion, and the cut-and-raised portion and the opening are close to each other, so that the guide is guided by the cut-and-raised portion. The exhausted gas can be efficiently flowed into the opening and can be guided to the outer periphery.
According to the invention of claim 5 , the opening area of the opening is larger than the opening area of the introduction part provided upstream of the cut-and-raised part in the exhaust flow direction, and the introduction of the cut-and-raised part is introduced. Since the exhaust introduced from the section can be reliably discharged from the induction section, the pressure loss can be reduced.

According to the invention of claim 6 , the thermal conductivity of the flat plate and the corrugated plate decreases from the central portion of the exhaust passage toward the outer peripheral portion, and the heat capacity is further increased. Since the conductivity is high and the thermal conductivity of the outer periphery of the exhaust passage is low, the heat quantity of the exhaust flowing through the center of the exhaust passage is diffused to the outer periphery of the exhaust passage, and the heat capacity of the outer periphery of the exhaust passage is large, so the exhaust passage Since the temperature can be maintained at the outer peripheral portion and the temperature of the exhaust gas flowing into the exhaust gas purification means can be made uniform, the exhaust gas purification performance can be improved.

According to the invention of claim 7 , the outermost peripheral portion of the exhaust guiding means is coated with the ceramic coating agent, and the release of the heat quantity of the outer peripheral portion of the exhaust passage into the atmosphere can be suppressed. Since the temperature of the exhaust gas flowing into the exhaust gas purification means can be made uniform, the exhaust gas purification performance can be improved.

1 is an overall configuration diagram of an engine to which an exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied. 1 is a development view of an exhaust induction device in an exhaust gas purification apparatus for an internal combustion engine according to the present invention. It is a cross section in the AA line of FIG. 1, and is sectional drawing of an exhaust induction device. It is sectional drawing in the BB line of FIG. FIG. 5 is an enlarged view of a portion C in FIG. 4 and an enlarged view of an exhaust guide portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the overall configuration of the engine 1 will be described. FIG. 1 shows an overall configuration diagram of an engine (internal combustion engine) 1 to which an exhaust gas purification apparatus for an internal combustion engine according to the present invention is applied.
The engine 1 is, for example, a common rail type in-line multi-cylinder diesel engine. The cylinder head 2 of the engine 1 is provided with an electromagnetic fuel injection nozzle 4 for each cylinder facing the combustion chamber 3. Each fuel injection nozzle 4 is connected to a common rail 6 by a high-pressure pipe 5, and the common rail 6 is connected to a high-pressure pump 8 via a high-pressure pipe 7. The high-pressure pump 8 has a function of supplying the fuel (light oil) stored in the fuel tank 9 to the common rail 6. The fuel supplied to the common rail 6 is stored in a high-pressure state and burns from each fuel injection nozzle 4. It is injected into the chamber 3.

  The cylinder head 2 is formed with an intake port 10 and an exhaust port 11 communicating with the combustion chamber 3 for each cylinder. The intake port 10 has an intake pipe 12 and the exhaust port 11 has an exhaust pipe (exhaust passage). 13 is connected. The cylinder head 2 is provided with an intake valve 14 that opens and closes the intake port 10 and an exhaust valve 15 that opens and closes the exhaust port 11.

The intake pipe 12 is provided with an electromagnetic intake throttle valve 16 that adjusts the intake air amount.
Between the exhaust pipe 13 and the intake pipe 12, an EGR pipe 18 provided with an EGR valve 19 which is an electromagnetic on-off valve is provided. One end of the EGR pipe 18 is connected to the exhaust pipe 13 in the vicinity of the exhaust port 11, and the other end is connected to the intake pipe 12 in the vicinity of the intake port 10, and the exhaust pipe 13 and the intake pipe 12 are communicated.

In the exhaust pipe 13, a diesel oxidation catalyst (hereinafter, referred to as DOC, forced regeneration means) 19, an exhaust inductor (exhaust induction means) 20, and a DPF (filter) 21 are provided in order from the upstream side. Yes. The DOC 19 is formed by supporting a catalytic noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) on a porous wall forming a passage, and oxidizes CO and HC in the exhaust to produce CO. ₂ and H ₂ O, and has a function of generating NO ₂ by oxidizing NO in the exhaust gas.

The exhaust induction device 20 has a function of correcting unevenness in the amount of oxidant that flows into the DPF 21 and oxidizes the PM accumulated in the DPF 21. A detailed configuration will be described later.
For example, the DPF 21 has a function of alternately closing the upstream side and the downstream side of the passage of the honeycomb carrier with plugs, collecting PM in the exhaust, and burning and removing PM with an oxidizing agent. It is formed by supporting a catalytic noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) on the porous wall forming the passage.

Further, when the DOC 19 is arranged upstream of the DPF 21 as described above, during normal engine operation, NO ₂ generated in the DOC 19 flows into the DPF 21 and is collected and accumulated in the DPF 21. It reacts with the ingredient soot to oxidize it. Oxidized soot becomes CO _{2 and} is removed from the DPF 21, thereby regenerating the DPF 21 continuously (continuous regeneration).

On the other hand, depending on the operating condition of the engine 1, the DPF 21 may not be sufficiently regenerated only by the continuous regeneration. Therefore, the PM is forcibly burned and removed based on the amount of accumulated PM in the DPF 21 (forced regeneration).
In the forced regeneration, fuel post-injection (sub-injection) is performed after the main injection of fuel during the operation of the engine 1, for example, after the expansion stroke, and exhaust gas containing unburned fuel (HC, CO, etc.) is discharged into the exhaust pipe. This is done by letting 13 discharge. The unburned fuel mixed in the exhaust flows into the DOC 19 and is oxidized, and the exhaust temperature is increased by the reaction heat of oxidation. As a result, the high-temperature exhaust gas flows into the DPF 21 on the downstream side of the exhaust gas, and the soot in the PM deposited on the DPF 21 is heated and burned, so that the DPF 21 can be forcibly regenerated.

Next, the configuration of the exhaust induction device 20 will be described.
FIG. 2 is a development view of the exhaust induction device 20 in the exhaust purification device of the engine 1 according to the present invention. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 4 is a cross-sectional view taken along the line BB of FIG. 3 and shows a cross-sectional view in a state where the exhaust induction device 20 is disposed in the exhaust pipe 13 of the engine 1. In addition, the arrow in a figure shows the flow of exhaust. FIG. 5 is an enlarged view of part C in FIG. 4 and shows an enlarged view of the cut-and-raised part 20h.

As shown in FIGS. 2 to 5, the exhaust inductor 20 has one end 20c that is thinner than the other end 20d (t1 <t3) and is made of metal and has a thin plate 20a and one end 20e at the other end 20f. Compared to a thin plate, the corrugated plate 20b made of a thin metal (t2 <t4) and having a thin plate thickness is wound on the other end 20d, 20f from the one end 20c, 20e side of the thin plate, and the flow of the exhaust is made. It is formed in a substantially cylindrical shape while forming a plurality of exhaust rectification passages 20g to be arranged. A plurality of cut and raised portions 20h are formed on the flat plate 20a. The cut-and-raised portion 20h is formed so as to protrude at a predetermined cut-and-raise angle (for example, 45 ° or less) toward the center in a state where the flat plate 20a and the corrugated plate 20b are overlapped and wound. The shim portion 20h is formed with an upstream opening (introduction portion) 20k so as to open on the upstream side in a state where it is disposed in the exhaust pipe 13, and further penetrates radially outward to penetrate the radially outer opening ( (Opening) 20m is formed by pressing into a bowl shape cut in half. The upstream opening 20k is formed with an opening area smaller than the radially outer opening 20m. Further, the radially outer opening 20m is formed so that the opening area increases from the center of the exhaust pipe 13 toward the outer periphery. Moreover, cut-and-lifted portions 20h, in the downstream after the predetermined distance from the most upstream portion 20n of the exhaust gas flow direction of the exhaust guide 20, so that the set置個number is reduced from the central portion of the exhaust pipe 13 As toward the downstream in order Formed. The corrugated plate 20b has a position corresponding to the radially outer opening 20m so that the radially outer opening 20m is not blocked by the corrugated plate 20b in a state where the flat plate 20a and the corrugated plate 20b are overlapped and wound. A relief portion 20j that is a relief hole is formed so as to have an opening area equal to or larger than the opening area of the radially outer opening 20m.

Next, the function of the exhaust induction device 20 configured as described above will be described.
As shown in FIG. 4, the exhaust gas flowing in from the upstream of the exhaust inductor 20 flows into the upstream opening 20k of the cut and raised portion 20h, is discharged from the radially outer opening 20m, and the exhaust is guided to the outer peripheral portion. . Further, the exhaust gas guided to the outer peripheral portion flows in from the upstream opening 20k of the downstream cut-and-raised portion 20h, is discharged from the radially outer opening 20m, and the exhaust gas is further guided to the outer peripheral portion.

As described above, according to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, the exhaust gas at the center of the exhaust pipe 13 having a high flow velocity is guided to the outer peripheral portion of the exhaust pipe 13 by the cut-and-raised portion 20 h of the exhaust inductor 20. I am doing so.
As a result, the flow rate of the exhaust gas introduced into the DPF 21 is made uniform, so that the temperature of the outer periphery of the DPF 21 can also be raised during continuous regeneration and forced regeneration, and PM deposited on the DPF 21 can be completely burned and removed. it can. Therefore, it is possible to reliably collect PM in the exhaust gas and improve the exhaust gas purification performance. Further, at the time of forced regeneration, PM deposition on the DPF 21 can be made uniform, and PM deposition on the DPF 21 can be made uniform. Therefore, lubrication can be achieved by prolonging the forced regeneration time by preventing excessive temperature rise and uneven PM deposition. Oil dilution of oil can also be prevented.

Further, the cut-and-raised portion 20h is not formed gradually from the central portion of the exhaust pipe 13 toward the outer peripheral portion in the downstream direction after a predetermined distance from the most upstream portion 20n in the exhaust flow direction of the exhaust inductor 20 as it goes downstream. I am doing so.
Thereby, since induction | guidance | derivation can be suppressed to the outer peripheral part of the exhaust pipe 13 of downstream exhaust_gas | exhaustion in the cut-and-raised part 20h, the pressure loss by the cut-and-raised part 20h can be reduced.

Further, the cut-and-raised portion 20h is formed so as to protrude and protrude at a predetermined angle toward the center when the flat plate 20a and the corrugated plate 20b are overlapped and wound.
Thereby, exfoliation of the exhaust gas at the cut-and-raised portion 20h can be prevented and the turbulent flow of the exhaust gas can be suppressed, so that the pressure loss can be reduced.
Although the description of the embodiment of the invention is finished as above, the embodiment of the present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the exhaust inductor 20 is provided between the DOC 19 and the DPF 21, but the present invention is not limited to this, and an injection nozzle that injects urea water (reducing agent) into the exhaust, urea water An exhaust induction device 20 may be provided between the NOx reduction catalyst that reduces NOx and removes NOx. In this case, the injected urea water can be diffused into the exhaust gas, and the urea water can be uniformly supplied to the NOx reduction catalyst, so that NOx in the exhaust gas can be reduced and purified well.

  In addition, in the state where the flat plate 20a and the corrugated plate 20b of the exhaust induction device 20 are overlapped and wound, the plate thickness is increased toward the outer periphery, but is not limited thereto. For example, in a state where the flat plate 20a and the corrugated plate 20b are overlapped and wound, a metal having a lower thermal conductivity and a larger heat capacity may be used as it goes to the outer periphery. It is possible to disperse the amount of heat of the exhaust flowing through the central portion of the pipe 13 and to maintain the amount of heat at the outer peripheral portion of the exhaust pipe 13. Therefore, when there is the DPF 21 downstream, the temperature of the exhaust gas flowing into the DPF 21 can be made uniform, so that PM can be completely removed by combustion during forced regeneration, and an excessive temperature rise can be prevented. Alternatively, in the case of a urea reduction SCR device having a NOx reduction catalyst downstream, the exhaust temperature flowing into the NOx reduction catalyst can be made uniform, so that the NOx purification performance of the NOx reduction catalyst can be improved. .

  Further, the outermost circumference (outermost circumference portion) of the exhaust induction device 20 may be coated with a ceramic coating agent. In this case, release of heat from the exhaust induction device 20 to the atmosphere can be suppressed. Therefore, when there is a DPF 21 downstream, it is possible to make the temperature of the exhaust gas flowing into the DPF 21 uniform, so that PM can be completely removed by combustion during forced regeneration, and an excessive temperature rise can be prevented. . Alternatively, in the case of a urea reduction SCR device having a NOx reduction catalyst downstream, the exhaust temperature flowing into the NOx reduction catalyst can be made uniform, so that the NOx purification performance of the NOx reduction catalyst can be improved. .

  The corrugated plate 20b has a position corresponding to the radially outer opening 20m so that the radially outer opening 20m is not blocked by the corrugated plate 20b in a state where the flat plate 20a and the corrugated plate 20b are overlapped and wound. The relief portion 20j is formed so as to have an opening area equal to or larger than the opening area of the radially outer opening portion 20m. However, the invention is not limited to this, and the relief portion 20j is not provided in the corrugated plate 20b. It is not necessary to form. Even in this case, the ridge line of the crest portion of the corrugated plate 20b is in contact with the flat plate 20a, and the crest portion of the corrugated plate 20b is wound around a position corresponding to the radially outer opening portion 20m so that the radially outer opening portion 20m is waved. Even if the crest of the plate 20b is blocked, the radially outer opening 20m is not completely blocked, and the same effect as in the above embodiment can be obtained.

Further, the cut-and-raised portion 20h is formed on the flat plate 20a. However, the present invention is not limited to this, and the cut-and-raised portion 20h is formed on the corrugated plate 20b, and the corrugated plate 20b is formed on the flat plate 20a. The relief portion 20j having an opening area larger than the cut-and-raised portion 20h may be formed. In this case, the same effect as in the above embodiment can be obtained.
Further, the radially outer opening 20m is formed so as to increase the opening area from the center of the exhaust pipe 13 toward the outer periphery, but is not limited to this, and the opening area is the same and the radial direction The number of outer openings 20m may be increased, and the opening area and number may be increased simultaneously.

1 engine (internal combustion engine)
4 Fuel injection nozzle (forced regeneration means)
19 DOC (Forced regeneration means)
20 Exhaust induction device (exhaust induction means)
20a Flat plate 20b Corrugated plate 20h Cut-and-raised part 20k Upstream opening (introduction part)
20m radial opening (opening)
21 DPF (filter)

Claims (7)

An exhaust purification means provided in an exhaust passage of the internal combustion engine for purifying exhaust;
A plurality of exhaust rectification passages are formed in the exhaust passage upstream of the exhaust purification means and extend in the exhaust circulation direction of the exhaust passage, and the exhaust is guided from the central portion of the exhaust passage to the outer peripheral portion. An exhaust induction means,
The exhaust guide means includes a plurality of guide portions for guiding exhaust from the exhaust rectification path on the central side to the exhaust rectification path outside through an opening provided in a side wall that defines the exhaust rectification path, induction portion is arranged such that the opening faces the product of the opening per unit area as the toward the outer periphery from the center of the exhaust passage is increased,
The exhaust guide means, in the downstream of the predetermined distance after the upstream end of the exhaust flow direction, and wherein the Rukoto formed such that the guiding portion in this order from the center of the exhaust passage decreases toward the downstream internal combustion Engine exhaust purification system. The guide portion opens a cut-and-raised portion such that a part of a side wall defining the exhaust rectification path protrudes toward a central portion of the exhaust passage and an upstream side of the cut-and-raised portion in the exhaust circulation direction. The exhaust emission control device for an internal combustion engine according to claim 1, further comprising an introduction portion to be formed. The exhaust induction means is formed by overlapping a flat plate and a corrugated plate, and further winding the overlapped flat plate and the corrugated plate to form a layer, and the exhaust rectification path is formed between the flat plate and the corrugated plate,
The exhaust purification device for an internal combustion engine according to claim 2 , wherein the opening is provided at least on the flat plate. The cut and raised portion is provided on the flat plate,
The exhaust purification device for an internal combustion engine according to claim 3 , wherein the opening is formed along with the formation of the cut and raised portion. The induction unit is characterized in that the larger opening area of the opening than an opening area of the inlet portion, an exhaust purification system of an internal combustion engine according to any one of claims 1 to 4. The exhaust guide means, said exhaust passage center low thermal conductivity as the toward the outer periphery from, further characterized in that to increase the heat capacity, an internal combustion engine according to any one of claims 1 to 5 Exhaust purification equipment. The exhaust purification device for an internal combustion engine according to any one of claims 1 to 6 , wherein the exhaust guide means is coated with a ceramic coating agent on an outermost peripheral portion.

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