JP2008128093A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of showing good conversion performance by mixing exhaust gas satisfactorily to eliminate bias of reducer concentration and to equalize air current distribution of exhaust gas on a reduction catalyst, and to make all section of the reduction catalyst effectively function. <P>SOLUTION: SCR catalyst (selective reduction NOx catalyst) 35 for converting NOx is stored in a casing 32, and a fin device 37 forming swirl and an injection nozzle 42 injecting urea water solution are arranged in an upstream side of the SCR catalyst 35. An orifice device 38 having a circulation hole 38a provided to pass through a center part thereof is arranged between the fin device 37 and the SCR catalyst 35. Air current distribution of exhaust gas is equalized by concentrating the swirl on a center part by the orifice device 38 on top of setting the fin device 37 to characteristics forming strong swirl. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device for an internal combustion engine (hereinafter referred to as an engine), and more particularly to an exhaust gas purification device that generates a swirling flow in exhaust gas for the purpose of improving purification efficiency.

In this type of exhaust purification device, a swirl flow is generated in the exhaust gas by fins or the like provided in the exhaust passage, and the purification efficiency of the exhaust purification device is improved by utilizing the stirring action and centrifugal force by this swirl flow. (For example, see Patent Documents 1 and 2).
In the exhaust purification device of Patent Document 1, a heating unit made of a sheath type heating element is disposed in a filter container, a stirring unit having a guide blade of a predetermined angle is provided on the downstream side, and a particulate is further provided on the downstream side. The filter to be collected is arranged, and the exhaust gas introduced into the filter container is heated by the heating unit, and the heated fluid is swirled by the stirring unit and sprayed on the filter in the stirring state. The filter is heated to remove particulates by incineration.

  In addition, the exhaust purification device of Patent Document 2 is provided with a swirl guiding portion for generating a swirling flow at the inlet of the casing of the exhaust purifying device, and an electric heating portion is provided along the inner peripheral surface of the exhaust swirl chamber formed in the casing. It is arranged and arranged by arranging a filter for collecting particulates at a downstream position of the exhaust swirl chamber in the casing, and by causing a swirl flow to be generated by the swirl guide when the exhaust gas is introduced into the casing, Particulates in the exhaust gas are centrifuged and incinerated to the electric heating part on the outer peripheral side, thereby preventing clogging of the filter.

On the other hand, in addition to the particulate collection filter, various exhaust gas purification devices are provided in the exhaust passage of the engine, for example, when an SCR catalyst (selective reduction type NOx catalyst) is provided to purify NOx in the exhaust gas. There is. SCR catalysts of this type, by injecting urea aqueous solution as the reducing agent from the injection nozzle provided in the exhaust passage is hydrolyzed to produce a NH ₃ by the exhaust heat and the water vapor in the exhaust gas, generated NH ₃ by the SCR catalyst NOx in the exhaust gas is reduced to harmless N ₂ to purify NOx.

  The NOx purification action of the SCR catalyst is greatly affected by the supply state of the urea aqueous solution, and in order to obtain a good purification action, the exhaust gas is sufficiently stirred to diffuse the urea aqueous solution well, and the circumferential direction on the SCR catalyst and It is necessary to make the air flow distribution of the exhaust gas in the radial direction uniform. The swirl flow of Patent Document 1 for heating the filter by the heated fluid and the swirl flow of Patent Document 2 for centrifugal separation of the particulates cannot satisfy such a requirement, and are suitable for this purpose. Fin devices have been put into practical use to generate a simple swirling flow.

  FIG. 4 shows an exhaust emission control device provided with this conventional fin device. The fin device 37 is disposed upstream of the SCR catalyst 35 in the casing 32, and urea is supplied upstream of the fin device 37. A spray nozzle 42 is disposed. The fin device 37 has a disk shape as a whole and is disposed in the casing 32 in a posture orthogonal to the exhaust flow direction. A partition wall portion 37a that constitutes the central portion of the fin device 37 includes an exhaust upstream side and an exhaust downstream side in the casing 32. Is partitioned. A large number of fins 37b are arranged between the partition wall portion 37a and the inner periphery of the casing 32, and each fin 37b forms a predetermined angle in the circumferential direction.

The exhaust gas of the engine is introduced into the casing 32 and reaches the fin device 37 together with the urea aqueous solution injected from the injection nozzle. The exhaust gas flowing through the central portion of the casing 32 is blocked by the partition wall portion 37a of the fin device 37, so that all The exhaust gas flows through the fins 37b on the outer peripheral side in the casing 32. At that time, the flow path is changed by the fins 37b and reaches the SCR catalyst 35 while generating a swirling flow. NOx purification using ₃ is performed. Due to the fact that the injection nozzle 42 is located at the center of the casing 32, the urea concentration on the upstream side of the fin device 37 is higher at the center than at the outer periphery. It is possible to reduce the unevenness of the urea concentration by flowing through the fins 37b.
Japanese Patent Laid-Open No. 10-259709 JP-A-6-129230

However, in the exhaust gas purification apparatus of FIG. 4 described above, although the deviation in urea concentration is reduced, it still occurs, and the exhaust gas in the radial direction on the SCR catalyst 35 is generated by circulating the exhaust gas through the fin 37b on the outer peripheral side of the casing. The air flow distribution tends to increase on the outer peripheral side.
There is a trade-off between the elimination of the urea concentration bias and the uniform distribution of the exhaust gas flow. For example, the swirl flow was strengthened by changing the fin angle, fin shape, etc., and the urea concentration bias was eliminated by promoting the stirring of the exhaust gas. In this case, the flow distribution of exhaust gas tends to increase on the outer peripheral side due to the centrifugal action of strong swirl flow, and conversely, when the swirl flow is weakened and the air flow distribution of exhaust gas is made uniform, the stirring of the exhaust gas becomes insufficient due to the weak swirl flow Therefore, the bias of urea concentration becomes more remarkable. Accordingly, due to the uneven concentration of urea in the exhaust gas due to poor agitation, or due to non-uniformity in the air flow distribution of the exhaust gas on the SCR catalyst 35, all parts of the SCR catalyst 35 cannot function effectively and are good. There was a problem that NOx purification performance could not be demonstrated.

  The present invention has been made to solve such problems. The object of the present invention is to thoroughly stir the exhaust gas to eliminate the uneven concentration of the reducing agent and to flow the exhaust gas over the reduction catalyst. It is an object of the present invention to provide an exhaust gas purification apparatus for an internal combustion engine that can make the distribution uniform, thereby effectively functioning all the parts of the reduction catalyst and exhibit good purification performance.

  In order to achieve the above object, an invention according to claim 1 comprises a casing that constitutes a part of an exhaust passage of an internal combustion engine and contains a reduction catalyst therein, and is provided on the upstream side of the reduction catalyst in the casing. The swirl flow generating means for generating a spiral swirl flow toward the exhaust downstream side of the exhaust gas, and the swirl flow generating means in the casing are disposed between the reduction catalyst and the swirl flow generating means. Reducing agent supply that supplies the reducing agent into the exhaust passage, provided in the exhaust passage at least upstream of the restricting means, and the restricting means for circulating the generated exhaust gas to the substantially central portion of the casing while flowing to the reduction catalyst side. Means.

  Accordingly, the exhaust gas of the internal combustion engine is caused to generate a swirling flow by the swirling flow generating means, and reaches the downstream reduction catalyst through the throttle means together with the reducing agent supplied from the reducing agent supply means. The radial flow distribution of the exhaust gas at the time when the swirl flow is generated by the swirl flow generating means tends to increase on the outer peripheral side from the center due to its own centrifugal action, but the exhaust gas is concentrated toward the center by the throttling means. After that, it reaches the reduction catalyst while diffusing again to the outer peripheral side by centrifugal action, and as a result, the air flow distribution of the exhaust gas supplied to the reduction catalyst is made uniform.

  In addition, since the non-uniformity of the air flow distribution of the exhaust gas is corrected in this way, even if the swirl flow by the swirl flow generating means is strengthened for the purpose of promoting stirring of the exhaust gas, there is a problem that the air flow distribution becomes non-uniform due to the centrifugal action. do not do. Although the reducing agent concentration in the exhaust gas is uneven due to the supply state of the reducing agent from the reducing agent supply means, the swirling flow is strengthened to promote the stirring of the exhaust gas and the concentration unevenness is eliminated.

According to a second aspect of the present invention, in the first aspect, the swirl flow generating means includes a partition wall that partitions the exhaust upstream side and the exhaust downstream side at a substantially central portion in the casing, and between the partition wall and the casing inner periphery. The plurality of fins are provided and form a predetermined angle in the circumferential direction with respect to the exhaust circulation direction.
Therefore, the exhaust gas flowing through the central part of the casing is blocked by the partition wall of the swirling flow generating means, so that the exhaust gas flows through the fins on the outer peripheral side in the casing, and the flow path is changed by the fins at that time and the swirling flow is generated. To occur. At this time, a strong swirling flow is generated in order to circulate all the exhaust gas through the large-diameter fin located on the outer peripheral side in the casing, and the swirling flow follows the so-called angular momentum conservation law of the swirling flow. Even after diffusing to the outer peripheral side through concentration, the high swirl speed is maintained without fading, and this strong swirl flow can more reliably eliminate the uneven concentration of the reducing agent.

According to a third aspect of the present invention, in the first or second aspect, the casing has substantially the same passage cross-sectional shape from the swirling flow generating means to the reduction catalyst, and the throttle means includes an exhaust upstream side and an exhaust downstream side in the casing. A partition plate is formed, and a circulation hole through which exhaust gas flows is provided substantially at the center.
Accordingly, the exhaust gas is concentrated toward the flow hole in the substantially central portion while being blocked by the throttle means on the outer peripheral side of the casing, and reaches the downstream reduction catalyst after flowing through the flow hole. Then, without reducing the passage cross-sectional shape of the casing partially to form the throttle means, the casing is kept in substantially the same passage cross-sectional shape, and the plate-like throttle means is arranged in the casing. Therefore, the inner volume of the casing is ensured to the maximum. The casing not only has a function of accommodating the exhaust purification device, but also has a silencing effect by circulating the exhaust gas in the internal space, and a high silencing effect is obtained by securing the internal volume of the casing in this way.

  As described above, according to the exhaust gas purification apparatus for an internal combustion engine of the first aspect of the present invention, the exhaust gas flow distribution generated by the swirling flow generating means is concentrated in the central portion by the throttling means, thereby making the air flow distribution of the exhaust gas uniform. In addition, the swirl flow can be strengthened to eliminate the uneven concentration of the reducing agent in the exhaust gas by accelerating the stirring of the exhaust gas, so that all the parts of the reduction catalyst can function effectively and exhibit good purification performance.

According to the exhaust emission control device for an internal combustion engine of the invention of claim 2, in addition to claim 1, a strong swirling flow is generated by arranging fins of the swirling flow generating means on the outer peripheral side of the casing, thereby reducing the concentration of the reducing agent. Can be more reliably eliminated.
According to the exhaust gas purification apparatus for an internal combustion engine of the third aspect of the invention, in addition to the first or second aspect, the inner volume of the casing can be ensured to the maximum and a high silencing effect can be obtained.

Hereinafter, an embodiment in which the present invention is embodied in an exhaust emission control device for a diesel engine will be described.
FIG. 1 is an overall configuration diagram showing an exhaust emission control device for a diesel engine according to this embodiment. The engine 1 is configured as an in-line 6-cylinder engine. Each cylinder of the engine 1 is provided with a fuel injection valve 2, and each fuel injection valve 2 is supplied with pressurized fuel from a common common rail 3 and is opened at a timing according to the operating state of the engine. The fuel is injected into the inside.

  An intake manifold 4 is mounted on the intake side of the engine 1, and the intake passage 5 connected to the intake manifold 4 is opened and closed by an air cleaner 6, a compressor 7a of the turbocharger 7, an intercooler 8, and an actuator 9a from the upstream side. An intake throttle valve 9 is provided. An exhaust manifold 10 is mounted on the exhaust side of the engine 1, and an exhaust passage 11 is connected to the exhaust manifold 10 via a turbine 7b of a turbocharger 7 connected coaxially with the compressor 7a.

  During operation of the engine 1, the intake air introduced into the intake passage 5 through the air cleaner 6 is pressurized by the compressor 7 a of the turbocharger 7, and then distributed to each cylinder through the intercooler 8, the intake throttle valve 9, and the intake manifold 4. These are introduced into the cylinder in the intake stroke of each cylinder. In the cylinder, fuel is injected from the fuel injection valve 2 at a predetermined timing and ignited and burned in the vicinity of the compression top dead center, and the exhaust gas after combustion rotates through the exhaust manifold 10 and then rotates the turbine 7b and then passes through the exhaust passage 11. It is discharged outside.

  On the other hand, the intake manifold 4 and the exhaust manifold 10 are connected by an EGR passage 17, and an EGR valve 18 and an EGR cooler 19 that are opened and closed by an actuator 18 a are provided in the EGR passage 17. During operation of the engine 1, part of the exhaust gas is recirculated as EGR gas from the exhaust manifold 10 side to the intake manifold 4 side according to the opening degree of the EGR valve 18.

  The exhaust passage 11 includes a first pipe 31a, a casing 32, a second pipe 31b, and a silencer (not shown) from the upstream side, and the rear end of the silencer is open to the atmosphere. The casing 32 has a substantially cylindrical shape extending in the front-rear direction of the vehicle, and the exhaust purification device of the present invention is accommodated in the casing 32. Hereinafter, the configuration of the exhaust gas purification apparatus will be described from the upstream side. The upstream oxidation catalyst 33 is disposed on the upstream side in the casing, and on the downstream side for collecting particulates (hereinafter referred to as PM) in the exhaust gas. A wall flow type DPF (diesel particulate filter) 34 is disposed. An SCR catalyst 35 (reduction catalyst) for purifying NOx in the exhaust gas is disposed on the downstream side of the DPF 34 with a predetermined gap, and a post-stage oxidation catalyst 36 is disposed on the downstream side thereof.

  The gap between the DPF 34 and the SCR catalyst 35 is divided into three at equal intervals L in the exhaust flow direction by the fin device 37 (swirl flow generating device) and the orifice device 38 (throttle means). Are referred to as a spray chamber 39, an aggregation chamber 40, and a diffusion chamber 41 from the upstream side. A spray nozzle 42 is disposed in the spray chamber 39, and the spray nozzle 42 is configured to be able to arbitrarily spray into the spray chamber 39 using a urea aqueous solution pumped from a tank (not shown) as a reducing agent. A temperature sensor 43 is installed on the downstream side of the injection nozzle 42, and the temperature in the spray chamber 39 is detected by the temperature sensor 43.

  2 is a cross-sectional view taken along the line II-II of FIG. 1 showing the fin device 37. As shown in FIGS. 1 and 2, the fin device 37 has a disk shape as a whole, and includes a spray chamber 39, an aggregation chamber 40, Between the two. The fin device 37 includes a partition wall portion 37a located at the center of the casing 32, and a plurality of fins 37b arranged in the circumferential direction between the periphery of the partition wall portion 37a and the inner periphery of the casing 32. For example, the material stainless steel plate is press-molded to integrally form the partition walls 37a and the fins 37b. The partition wall portion 37a has a flat plate shape to prevent the exhaust gas from flowing, and the fins 37b form the same predetermined angle in the circumferential direction with respect to the exhaust gas flow direction so that the exhaust gas from the spray chamber 39 flows between the fins 37b. However, by changing the flow path, a swirling flow spiraling toward the exhaust downstream side in the aggregation chamber 40 is generated. In particular, in this embodiment, the specifications of the fin device are set so as to give priority to the generation of a strong swirling flow, and specifically, the fin angle and fin shape are set so as to change the exhaust gas flow path abruptly. ing.

  3 is a cross-sectional view taken along the line III-III in FIG. 1 showing the orifice device 38. As shown in FIGS. 1 and 3, the orifice device 38 has a disk shape with a through hole 38a penetrating therethrough. Thus, the aggregation chamber 40 and the diffusion chamber 41 are disposed so as to be partitioned. The orifice device 38 is manufactured, for example, by punching the center part of a stainless steel plate of the material by press molding, and allows the exhaust gas to flow toward the diffusion chamber 41 only at the location of the flow hole 38a while preventing the flow of the exhaust gas from the aggregation chamber 40. .

  On the other hand, the intake throttle valve 9, exhaust throttle valve 12, EGR valve 18, and swirl valve 20 actuators 9a, 12a, 18a, 20a, the fuel injection valve 2, the fuel nozzle 42, the temperature sensor 43, etc. are connected to an ECU 51 (electronic control unit). ) And is driven and controlled by the ECU 51 based on detection information from the sensors. For example, the ECU 51 operates the engine 1 by controlling the injection amount, injection pressure, and injection timing of the fuel injection valve 2 based on the operating state of the engine 1 such as the engine speed and load, and opens the EGR valve 18 by the actuator 18a. The EGR reflux amount is adjusted by controlling the degree.

The ECU 51 controls post-injection for forced regeneration of the DPF 34, urea supply from the injection nozzle 42 for NOx purification by the SCR catalyst 35, and so on. The NOx purification action by the SCR catalyst 35 will be described.
The DPF 34 has an action of collecting PM in the exhaust gas. In an operation state where the exhaust gas temperature of the engine 1 is relatively high, NO ₂ is generated from NO in the exhaust gas by the oxidation action of the pre-stage oxidation catalyst 33, and the NO ₂ The PM collected in the DPF 34 by the oxidation reaction is continuously incinerated and removed, whereby the DPF 34 is regenerated. On the other hand, when such an operation state in which the continuous regeneration action cannot be obtained continues, post injection is appropriately executed after the main injection by the ECU 51, and PM is incinerated and removed together with the fuel supplied onto the DPF 34. Forced playback. Note that CO generated during PM combustion in forced regeneration is oxidized to CO ₂ by the post-stage oxidation catalyst 41.

In addition, since the SCR catalyst 35 needs to supply NH ₃ (ammonia) for NOx purification, the ECU 51 injects the urea aqueous solution injection amount from the injection nozzle 42 based on the operating state of the engine 1, the detection value of the temperature sensor 43, and the like. To control. The injected urea aqueous solution is hydrolyzed by the exhaust heat and the water vapor in the exhaust gas to produce NH ₃ , and this NH ₃ reduces the NOx in the exhaust gas to harmless N ₂ on the SCR catalyst 35, thereby purifying the NOx. On the other hand, surplus NH _{3 at} this time is oxidized to NO by the post-stage oxidation catalyst 36.

A hydrolysis catalyst that acts to hydrolyze urea into NH ₃ may be disposed upstream of the SCR catalyst 35, or an aqueous ammonia solution may be injected from the injection nozzle 42 instead of the aqueous urea solution. Also good.
In this embodiment, an orifice device 38 is disposed between the fin device 37 and the SCR catalyst 35, and the exhaust gas generated by the swirling flow by the fin device 37 is circulated to the orifice device 38, whereby the following operation is performed. An effect is obtained.

The exhaust gas flowing through the front-stage oxidation catalyst 33 and the DPF 34 is introduced into the spray chamber 39, and the urea aqueous solution is injected from the injection nozzle 42 in the spray chamber 39. The exhaust gas together with the urea aqueous solution changes the flow path when flowing through the fins 37b of the fin device 37 to generate a swirling flow in the aggregation chamber 40, and flows through the flow holes 38a of the orifice device 38 while the swirling flow is generated. Are introduced into the diffusion chamber 41. Thereafter, the exhaust gas reaches the SCR catalyst 35 together with the urea aqueous solution through the diffusion chamber 41 and is used for NOx purification using NH ₃ on the SCR catalyst 35.

Here, in the spray chamber 39, the exhaust gas flowing through the central portion of the casing 32 is blocked by the partition wall portion 37 a of the fin device 37, so that all the exhaust gas flows through the large-diameter fins 37 b located on the outer peripheral side in the casing 32. Therefore, a strong swirl flow is generated, and the setting of the fin angle and fin shape described above contributes to the generation of a strong swirl flow.
Thereafter, in the aggregation chamber 40, the exhaust gas is aggregated toward the central circulation hole 38 a while being blocked by the orifice device 38 on the outer peripheral side of the casing 32, and circulates through the circulation hole 38 a while crossing each other to enter the diffusion chamber 41. It is introduced and reaches the SCR catalyst 35 while diffusing to the outer peripheral side again by centrifugal action in the diffusion chamber 41. Note that the swirl radius changes significantly in the process of diffusing to the outer peripheral side after being concentrated to the central part by the orifice device 38, but even after diffusing again to the outer peripheral side in accordance with the so-called law of conservation of angular momentum of the swirl flow. Maintains a high turning speed without slowing down.

  The radial airflow distribution of the exhaust gas at the time when the swirling flow is generated by the fin device 37 tends to increase on the outer peripheral side from the center due to its own centrifugal action, and it is not possible to generate a strong swirling flow as described above. The uniform tendency becomes more prominent. However, the non-uniformity in the air flow distribution of the exhaust gas is corrected through the aggregation in the aggregation chamber 40 and the diffusion in the diffusion chamber 41, and reaches the SCR catalyst 35 with the air flow distribution made uniform.

Further, the urea concentration in the exhaust gas is biased due to the injection nozzle 41 being positioned at the center of the casing 32. However, the swirling flow is strengthened to promote the stirring of the exhaust gas, and the concentration bias is eliminated. The In addition, since the exhaust gas collected in the flow holes 38a of the orifice device 38 is mixed and stirred, this phenomenon also contributes to the elimination of the urea concentration unevenness.
Therefore, according to the exhaust gas purification apparatus of the present embodiment, it is possible to achieve a high level of both the elimination of the urea concentration unevenness in the exhaust gas, which originally has a trade-off relationship, and the uniform distribution of the air flow of the exhaust gas. After the urea aqueous solution is uniformly distributed, the exhaust gas is concentrated and diffused using the orifice device 38, so that the air flow distribution of the exhaust gas supplied to the SCR catalyst 35 can be made uniform. All sites can be effectively functioned to exhibit good NOx purification performance.

  Further, the casing 32 not only has a function of accommodating the exhaust purification device but also has a silencing action by circulating exhaust gas in the internal space. As is apparent from FIG. 1, the casing 32 has a substantially cylindrical shape extending in the vehicle front-rear direction. That is, since the plate-shaped orifice device 38 is disposed in the casing 32 while keeping the same passage cross-sectional shape, the internal volume of the casing 32 is ensured to the maximum. Therefore, when the exhaust gas flows through the casing 32, a sufficient silencing effect is achieved, and it is possible to obtain advantages such as reduction in vehicle noise or improvement in vehicle mounting due to downsizing of a silencer installed separately.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the exhaust gas purification device of the diesel engine 1 provided with the SCR catalyst 35 for NOx purification is embodied. However, the present invention is not limited to this as long as the engine is provided with a reduction catalyst that requires supply of a reducing agent. . For example, a storage-type NOx catalyst that stores NOx in exhaust gas is provided in the exhaust passage, and in order to release and reduce the stored NOx from the NOx catalyst, NOx purge is periodically performed to inject fuel into the exhaust passage as a reducing agent. It may be applied to the engine that needs it. In this case, the SCR catalyst 35 in FIG. 1 is replaced with an occlusion type NOx catalyst. However, by arranging an orifice device 38 between the fin device 37 and the NOx catalyst, the exhaust gas is contained in the exhaust gas as in the above embodiment. The effect of improving the NOx purification performance can be obtained by resolving the uneven fuel concentration and uniforming the air flow distribution of the exhaust gas at a high level.

Moreover, in the said embodiment, although the injection nozzle 42 was provided in the upstream (inside the spray chamber 39) of the fin apparatus 37, since the same effect is obtained if it is upstream from the orifice apparatus 38, the installation position is For example, the injection nozzle 42 may be disposed between the fin device 37 and the orifice device 38 (in the aggregation chamber 40).
Moreover, in the said embodiment, although the fin apparatus 37 which consists of the partition part 37a of the center part and the many fins 37b of the circumference | surroundings was applied, the structure of the fin apparatus 37 is not limited to this, A swirl flow Any change can be made as long as it causes the problem.

  Further, in the above embodiment, all the components of the exhaust purification device are accommodated in the single casing 32. However, considering the mounting property on the vehicle, for example, the pre-oxidation catalyst 33 and the DPF 34 are accommodated in separate casings. May be.

1 is an overall configuration diagram illustrating an exhaust emission control device for a diesel engine according to an embodiment. It is the II-II sectional view taken on the line of FIG. 1 which shows a fin apparatus. It is the III-III sectional view taken on the line of FIG. 1 which shows an orifice apparatus. It is a block diagram which shows the exhaust gas purification apparatus of the diesel engine of a prior art.

Explanation of symbols

1 engine (internal combustion engine)
11 Exhaust passage 32 Casing 35 SCR catalyst (reduction catalyst)
37 Fin device (swirl flow generating means)
37a Partition part 37b Fin 38 Orifice device (throttle means)
38a Flow hole 42 Injection nozzle (reducing agent supply means)

Claims (3)

A casing that constitutes a part of the exhaust passage of the internal combustion engine and contains a reduction catalyst therein;
A swirl flow generating means provided on the upstream side of the reduction catalyst in the casing and generating a swirl flow spiraling toward the exhaust downstream side of the exhaust gas of the internal combustion engine;
The exhaust gas that is disposed between the swirling flow generating means and the reduction catalyst in the casing and that generates the swirling flow by the swirling flow generating means is concentrated on the substantially central portion of the casing toward the reducing catalyst side. Squeezing means for circulation;
An exhaust gas purification apparatus for an internal combustion engine, comprising: a reducing agent supply means provided at least upstream of the throttle means in the exhaust passage and supplying a reducing agent into the exhaust passage.   The swirling flow generating means is provided between a partition wall partitioning the exhaust upstream side and the exhaust downstream side at a substantially central part in the casing, and between the partition wall part and the casing inner periphery, and is disposed in the exhaust circulation direction. The exhaust emission control device for an internal combustion engine according to claim 1, further comprising a plurality of fins having a predetermined angle in the circumferential direction. The casing has substantially the same passage cross-sectional shape from the swirl flow generating means to the reduction catalyst,
3. The throttle means according to claim 1, wherein the throttle means has a plate shape that divides the exhaust upstream side and the exhaust downstream side in the casing, and a flow hole through which exhaust gas flows is provided substantially at the center. An exhaust gas purification apparatus for an internal combustion engine as described.

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