JP6846212B2 - Swirling flow generator - Google Patents

Description

The present invention relates to a swirling flow generator used in an exhaust gas purification device.

An exhaust gas purification device (appropriately referred to as a purification device) that mixes an exhaust gas and a reducing agent and reduces and purifies nitrogen oxides contained in the exhaust gas with a reduction catalyst is known. For example, the purification device described in Patent Document 1 has a reduction catalyst provided inside an exhaust pipe through which exhaust gas discharged from an internal combustion engine flows, and a reduction catalyst arranged upstream of the reduction catalyst to generate a swirling flow in the exhaust gas. It is configured to include a swirling flow generator for the purpose.

14A and 14B show an example of such an exhaust gas purification device according to the prior art, FIG. 14A is a schematic view, and FIG. 14B is an enlarged perspective view of a main portion V shown in FIG. 14A. As shown in FIG. 14A, the exhaust gas purification device 5 injects and supplies a reducing agent (urea water or the like) to the exhaust pipe 1, the reducing catalyst 2, and the exhaust gas flowing on the upstream side of the reducing catalyst 2. The reducing agent injection nozzle 3 as a means and the upstream side of the reduction catalyst 2 in the exhaust pipe 1 (specifically, the location where the reducing agent is sprayed on the exhaust gas by the reducing agent injection nozzle 3 (“reducing agent” in the figure). It is provided with a swirl flow generator 4 provided on the upstream side) of the spray unit) to generate a swirl flow in the exhaust gas.

Further, as shown in FIG. 14B, the swirling flow generator 4 is a fin structure, and has a plurality of cuts (in this case, four each) formed by combining a linear cut and a quarter arc-shaped cut. A support column 4a and a fan-shaped blade (fan-shaped fin 4b) are formed by forming the plate and bending it so as to cause this notch, and these four fan-shaped fins 4b are arranged so as to be circular.

In such a purification device 5, the exhaust gas passes through the fan-shaped fins 4b of the swirling flow generator 4 to form a turbulent flow or a swirling flow, which promotes the diffusion of the reducing agent into the exhaust gas (in other words, the exhaust gas and the reducing agent. (Increase the mixing ratio of). As a result, the reducing agent can be supplied to the reduction catalyst 2 in a uniform state, and the exhaust gas purification performance is ensured to a certain level or higher. Therefore, the reduction efficiency of nitrogen oxides in the exhaust gas can be improved. Can be planned.

Japanese Unexamined Patent Publication No. 2006-292333

By the way, in order to tighten exhaust gas regulations in recent years, the amount of reducing agent added tends to increase, and in order to reduce the amount of reducing agent added, it is desired to develop a swirling flow generator having more excellent diffusivity. If the swirling ability of the swirling flow generator 4 can be improved, the diffusion of the reducing agent in the exhaust gas can be promoted, and the reducing agent can be supplied to the reduction catalyst in a more uniform state. Therefore, the exhaust gas purification performance is improved. Therefore, it is desirable to improve the turning force of the swirling flow generator 4.

On the other hand, when the exhaust gas passes through the swirl flow generator 4, a large resistance is generated by the swirl flow generator 4, so that there is a problem that the pressure loss also becomes large. Therefore, if the resistance generated by the swirl flow generator 4 can be reduced, the pressure loss in the swirl flow generator 4 can be reduced, and the fuel consumption of the internal combustion engine can be improved. Therefore, it is desirable to reduce the resistance generated by the swirling flow generator 4.

However, if an attempt is made to improve the swirling ability of the swirling flow generator 4, the resistance generated by the swirling flow generator 4 tends to increase, and conversely, the resistance generated by the swirling flow generator 4 is reduced. If this is the case, the swirling ability of the swirling flow generator 4 tends to decrease.

Therefore, as shown in FIGS. 15 (a) to 15 (c), the present inventor uses a swirling flow generator (not shown) to symmetrically direct the directions in the exhaust pipe 1 in opposite directions. If it is possible to generate a twin-shaped vortex flow (swirl flow A, swirl flow B) that flows while rotating, the resistance generated by the swirl flow generator can be reduced while improving the diffusivity of the injected reducing agent. I thought I could do it.

The present invention has been made in view of such circumstances, and an object of the present invention is to generate a swirling flow capable of suppressing resistance to an exhaust gas flow while improving the diffusibility of the reducing agent injected into the exhaust pipe. To provide the equipment.

In order to achieve the above-mentioned object, the swirl flow generator according to the present invention
An exhaust pipe through which exhaust gas flows, a reduction catalyst provided in the exhaust pipe for reducing and purifying nitrogen oxides contained in the exhaust gas, and a reducing agent supply means for injecting and supplying a reducing agent to the exhaust gas flowing upstream of the reduction catalyst. An exhaust gas purifying device including, which is a swirling flow generator that is arranged upstream of the reduction catalyst in the exhaust pipe and generates a swirling flow in the exhaust gas.
It is characterized in that it is arranged symmetrically with respect to a surface including the central axis of the exhaust pipe in the exhaust pipe, and is composed of a plate that closes at least 40% of the cross-sectional area of the exhaust pipe in a direction orthogonal to the central axis. To do.

According to this, the exhaust gas flowing in the exhaust pipe is guided from the upstream side to the downstream side by the plate, and in the process, the exhaust gas is divided into both sides (for example, symmetrical) by the plate and downstream along the inner wall of the exhaust pipe. Since it flows to the side, a swirling flow is generated. Therefore, it is possible to generate a twin-shaped vortex (swirl flow) that flows while rotating in opposite directions symmetrically in the direction of travel in the exhaust pipe, and the diffusivity of the reducing agent injected into the exhaust pipe is increased. Can be improved. At this time, the exhaust gas is guided from the upstream side to the downstream side along the plate and flows to the downstream side along the inner wall of the exhaust pipe, so that the resistance when generating the swirl flow in the swirl flow generator is reduced. be able to. Thus, a swirling flow having low resistance and excellent diffusivity can be generated. Moreover, since the diffusion of the reducing agent in the swirling exhaust gas can be promoted, the reducing agent can be supplied to the reduction catalyst in a more uniform state, and the exhaust gas purification performance can be improved. ..

At this time, it is preferable that the plate has a V-shape in which the upstream side end portion is bent and spreads toward the pair of downstream side end portions. Further, it is preferable that at least one of the upper and lower sides of each of the pair of left and right surfaces from the upstream end to the downstream end of the plate is curved along the inner wall of the exhaust pipe. .. Further, it is preferable that the plate is arranged along the inner wall surface on the outer diameter side or the inner diameter side in the exhaust pipe at the portion where the exhaust pipe is bent.

According to these, it is possible to simplify the configuration for generating a swirling flow by regulating the flow of the exhaust gas.

Further, in the swirling flow generator,
The exhaust gas purification device is
A tubular part whose one end fits on the upstream side of the exhaust pipe,
A cap member having a cap shape having a closing portion that closes the other end of the tubular portion, and having an opening for flowing the exhaust gas to the reduction catalyst arranged on the downstream side of the exhaust pipe toward the side. And, with more
The plate may be arranged in front of the opening in the inner space of the cap member.

According to this, by arranging the plate in front of the opening in the cap member, a pressure difference is generated between the opening side and the opposite side with the plate as a boundary, and this pressure difference is used to generate exhaust gas in the vicinity of the opening. A swirling flow can be generated. Therefore, the configuration for generating the swirling flow can be simplified.

At this time, the opening has a flat shape in the flow direction of the exhaust gas.
It is preferable that the upstream end of the plate is bent and a pair of downstream ends are arranged so as to extend toward both ends in the longitudinal direction of the opening.

According to this, since the flow direction of the exhaust gas toward the flat opening can be regulated by the plate, it is possible to easily generate a swirling flow.

According to the present invention, it is possible to generate a swirling flow having low resistance and excellent diffusivity.

An exhaust gas purification device having a swirling flow generator according to the first embodiment is shown, (a) is a perspective view schematically showing a main part thereof, and (b) is a cross-sectional view showing the main part as viewed from the upstream side. .. An exhaust gas purification device having a swirling flow generator of FIG. 1 is shown, (a) is a plan view, and (b) is a side view. The swirling flow generator of the first embodiment is shown, (a) is a flow analysis result (flow velocity) seen from the side surface, and (b) is a figure showing a flow analysis result (flow velocity) seen from the downstream side of the cross section. An exhaust gas purification device having a swirling flow generator according to a second embodiment is shown, and (a) is a perspective view shown from the downstream side when arranged on the outer diameter side of a bent portion of the exhaust pipe, (b). Is a plan view shown from the downstream side thereof, (c) is a partial perspective view shown from the outer diameter side thereof, and (d) is a side view. It is a perspective view which shows the main part in the exhaust gas purification apparatus of FIG. 4 as seen from the inner diameter side of an exhaust pipe. An exhaust gas purification device having a swirling flow generator according to a third embodiment is shown, (a) is a perspective view shown from the downstream side when arranged on the inner diameter side of a bent portion of the exhaust pipe, and (b) is a perspective view. The plan view shown from the downstream side thereof, (c) is a partial perspective view shown from the outer diameter side thereof, and (d) is a side view. It is a perspective view which shows the main part in the exhaust gas purification apparatus of FIG. 6 as seen from the inner diameter side of an exhaust pipe. It is a figure which shows the flow analysis result (flow velocity) of each of the swirl flow generator (a) of the 2nd embodiment and the swirl flow generator (b) of the 3rd embodiment. It is sectional drawing which shows the whole structure of the exhaust gas purification apparatus in 4th Embodiment. It is a perspective view which shows the swirling flow generator used for the exhaust gas purification apparatus of FIG. It is a figure which shows the state which the cap member was seen from the opening side. It is an enlarged view which shows the X part of FIG. It is a figure which shows the inner space of a cap member. In order to explain the prior art, (a) is a schematic view showing an example of an exhaust gas purification device, and (b) is a perspective view schematically showing an example of a swirling flow generator. In order to explain the twin-shaped vortex flow, (a) is a conceptual diagram shown from the downstream side of the exhaust gas purification device, (b) is an arrow view of aa in (a), and (c) is b in (b). −B is an arrow view.

Hereinafter, embodiments of the swirl flow generator according to the present invention will be described with reference to the drawings. However, although the embodiments described below are provided with various technically preferable limitations for carrying out the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples.

<First Embodiment>
<Exhaust gas purification device>
First, an exhaust gas purification device using the swirling flow generator of the present embodiment will be described.
As shown in FIG. 1 (a), the swirl flow generator 10 of the present embodiment is used in a conventionally known exhaust gas purification device 5 (see, for example, FIG. 14 (a)) and is used as an engine (not shown). ) Is incorporated in the exhaust pipe 1 for discharging the exhaust gas. The purification device 5 injects a reducing agent 2 (see FIG. 14A) for reducing and purifying nitrogen oxides contained in the exhaust gas and a reducing agent (for example, ammonia) on the exhaust gas flowing upstream of the reduction catalyst 2. It includes a reducing agent injection nozzle 3 as a reducing agent supply means for supplying. Then, by disposing the swirl flow generator 10 of the present embodiment in place of the conventional swirl flow generator 4 on the upstream side of the reducing agent injection nozzle 3, a swirl flow is generated in the exhaust gas. ing. That is, the exhaust gas purification device 5 has almost the same configuration as the conventional general exhaust gas purification device 5 except that the swirl flow generator 10 is different.

<About swirl flow generator>
Next, the swirl flow generator 10 of the present embodiment will be described.
Specifically, as shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), the swirl flow generator 10 is symmetrical with respect to a plane including its central axis inside the exhaust pipe 1. It consists of a plate that is arranged in and closes at least 40% of the cross-sectional area of the exhaust pipe 1 in the direction orthogonal to the central axis (that is, in the radial direction).

The swirl flow generator 10 is formed in a V shape in which the upstream side end portion 10a is bent and spreads toward the pair of downstream side end portions 10b and 10c. Further, the swirl flow generator 10 has at least one of the upper and lower sides of each of the pair of left and right surfaces from the upstream end 10a to the downstream ends 10b and 10c (upper sides 10d and 10e in the case of this embodiment). Is curved along the inner wall of the exhaust pipe 1. In the swirling flow generator 10 constructed in this way, the curved upper sides 10d and 10e located at the outer edge thereof are configured to come into contact with the inner wall surface of the exhaust pipe 1. That is, the swirl flow generator 10 is arranged so as to block the upper side of the flow path in the exhaust pipe 1 by the upper sides 10d and 10e.

In the swirling flow generator 10 having such a configuration, the exhaust gas flowing in the exhaust pipe 1 is guided separately to the left and right by the upstream end portion 10a (see arrows X and Y in FIGS. 2A and 2B), and is guided to the downstream side. In the process of flowing toward the ends 10b and 10c, the upper flow path in the exhaust pipe 1 is blocked by the upper sides 10d and 10e (the flow of exhaust gas is regulated), so that the flow is from upper to lower. It is guided (see arrow Z in FIG. 2B).

In this way, the exhaust gas that has flowed separately to both sides by the upstream end portion 10a moves downward through the region K that regulates the flow of the exhaust gas surrounded by the upper sides 10d and 10e and the inner wall of the exhaust pipe 1. By being guided, a vortex flow is generated due to the pressure difference between the upstream side and the downstream side of the swirl flow generator 10. Here, since the swirling flow generator 10 has a symmetrical V-shape, twin-shaped swirling flows that rotate in opposite directions along the inner wall of the exhaust pipe 1 (from the downstream side as shown in FIG. 15A). Looking at the upstream side, there is a clockwise swirling flow A on the left side and a counterclockwise swirling flow B on the right side).

Then, these twin-shaped swirling flows are guided to the downstream side while continuing to swirl, so that the swirling can be sustained over a wide range toward the downstream side. That is, in the swirl flow generator 10, it is possible to generate a swirl flow having excellent diffusivity by diffusing (stirring) the reducing agent sprayed in the exhaust gas purification device 5, and to improve its sustainability. ing.

Further, in the swirl flow generator 10, the upper end side end portion 10a is bent, is arranged along the flow of the exhaust gas in the exhaust pipe 1, and extends to the pair of downstream side end portions 10b, 10c. Since the upper sides 10d and 10e located on the outer edge are configured to come into contact with the inner wall surface of the exhaust pipe 1, the exhaust gas separated to the left and right by the upstream end portion 10a while suppressing the resistance to the flow of the exhaust gas can be generated. A twin-shaped swirling flow is formed through the region K surrounded by the upper sides 10d and 10e and the inner wall of the exhaust pipe 1, and flows smoothly along the inner wall of the exhaust pipe 1. Therefore, the resistance generated by the exhaust gas purification device 5 becomes small.

In the present embodiment, the case where the swirling flow generator 10 is provided on the upstream side of the reducing agent spraying unit (see FIG. 14A) has been described, but the present invention is not limited to this. The swirl flow generator 10 may be arranged on the downstream side of the reducing agent spraying portion as long as it is on the upstream side of the reducing catalyst 2 (see FIG. 14A).

Further, in the present embodiment, the case where the swirl flow generator 10 is arranged inside the exhaust pipe 1 so as to be symmetrical with respect to the central axis thereof has been described, but the present invention is not limited to this, and the point is exhaust. As long as it is arranged symmetrically with respect to the surface including the central axis of the tube 1, it may be symmetrical in the vertical direction, diagonally, or the like.

According to the swirling flow generator 10 as described above, the exhaust gas flowing in the exhaust pipe 1 is divided into both sides (left and right) by the upstream end portion 10a of the swirling flow generator 10 and guided to the downstream side. In the process of flowing to the downstream end portions 10b and 10c, the exhaust gas is guided downward through the region K that regulates the flow of exhaust gas surrounded by the upper sides 10d and 10e and the inner wall of the exhaust pipe 1. , Since it flows downstream as a twin-shaped vortex (swirl flow) that rotates in opposite directions along the inner wall of the exhaust pipe 1, as shown in the flow analysis results showing the flow velocity in FIGS. 3 (a) and 3 (b). It is possible to generate a symmetrical swirling flow having excellent diffusivity by diffusing (stirring) the reducing agent sprayed in the exhaust gas purifying device 5 over a wide range in the exhaust pipe 1.

Moreover, the plate constituting the swirl flow generator 10 is configured so that the upper sides 10d and 10e located at the outer edge come into contact with the inner wall surface of the exhaust pipe 1, and the upper end side end portion 10a is the exhaust gas in the exhaust pipe 1. Since it is arranged along the flow of the exhaust gas, the resistance to the flow of the exhaust gas can be suppressed, the twin swirling flow can flow smoothly along the plate, and the resistance generated by the exhaust gas purification device 5 can be reduced. .. Thus, according to the swirling flow generator 10 of the present embodiment, it is possible to generate a swirling flow having low resistance and excellent diffusivity.

Further, since the diffusivity of the reducing agent sprayed in the exhaust gas purification device 5, that is, the diffusion of the reducing agent in the swirling exhaust gas can be promoted, the reducing agent 2 (see FIG. 14A) can be promoted. Therefore, the reducing agent can be supplied in a more uniform state, and the exhaust gas purification performance can be improved.

Further, since the structure for generating the swirling flow by regulating the flow of the exhaust gas can be configured by the V-shaped plate, the configuration for generating the swirling flow can be simplified.

<Second embodiment>
Next, the second embodiment of the present invention will be described. The swirl flow generator 20 of the second embodiment according to the present invention is used for a conventionally known exhaust gas purification device 5 (see, for example, FIG. 14A) and the like. In the exhaust gas purification device 5, a communication portion 6 for attaching a reducing agent spraying portion (reducing agent injection nozzle 3 as a reducing agent supplying means, etc.) is provided at a portion of the exhaust pipe 1 bent into an elbow shape. And, except that the structure of the swirling flow generator 20 is different, it is the same as the first embodiment described above, and thus detailed description of the exhaust gas purification device 5 will be omitted.

In the present embodiment, an opening 1a for injecting a reducing agent into the exhaust pipe 1 is formed on the outside of the elbow portion of the exhaust pipe 1 (lower right side in FIG. 4D), and a communication portion is formed. 6 is provided in the exhaust pipe 1 so that the inside thereof communicates with the opening 1a. As shown in FIGS. 4A to 4D and FIG. 5, the swirl flow generator 20 is arranged symmetrically with respect to the surface including the central axis of the exhaust pipe 1 so as to surround the opening 1a, and the central axis thereof. It consists of a plate that closes at least 40% of the cross-sectional area of the exhaust pipe 1 in the direction orthogonal to (that is, the radial direction).

Specifically, the swirl flow generator 20 is bent with the upstream side end portion 20a as the top portion, and is formed so as to spread in a V shape toward the pair of downstream side end portions 20b and 20c. Further, in the swirling flow generator 20, the pair of left and right surfaces 21 and 22 from the upstream side end portion 20a to the downstream side end portions 20b and 20c are outer diameter side sides 21a, which are in contact with the inner wall surface of the exhaust pipe 1, respectively. 22a forms a curved portion along the inner wall of the exhaust pipe 1, and the inner diameter side sides 21b and 21b facing the curved portion are substantially linear, and are formed in a substantially half-moon shape as a whole.

Then, the swirl flow generator 20 has the outer diameter side sides 21a and 22a inside the exhaust pipe 1 so that the pair of surfaces 21 and 22 are symmetrical with respect to the surface including the central axis thereof inside the exhaust pipe 1. By being arranged so as to be in contact with the wall surface, these surfaces 21 and 22 surround the opening 1a and close the outer diameter side of the flow path in the bent portion of the exhaust pipe 1.

In the swirling flow generator 20 having such a configuration, the exhaust gas flowing on the outer diameter side in the exhaust pipe 1 is guided separately to the left and right starting from the upstream end portion 20a (FIGS. 4C and 5 arrows X and Y). (See), in the process of flowing to the downstream end portions 20b, 20c side, the outer diameter side sides 21a, 22a are arranged in contact with the inner wall of the exhaust pipe 1 by the surfaces 21 and 22 outside the exhaust pipe 1. Since the flow path on the diameter side is blocked (the flow of exhaust gas is regulated), it is guided from the outer diameter side to the inner diameter side (see arrow Z in FIG. 4D).

In this way, the exhaust gas that has flowed separately to both sides by the upstream end portion 20a goes to the inner diameter side through the region K that regulates the flow of the exhaust gas surrounded by the surfaces 21 and 22 and the inner wall of the exhaust pipe 1. By being guided, a vortex flow is generated due to the pressure difference between the upstream side and the downstream side of the swirl flow generator 20. Here, since the swirling flow generator 20 has a symmetrical V-shape, it becomes a twin-shaped swirling flow that rotates in opposite directions along the inner wall of the exhaust pipe 1, and flows to the downstream side while continuing swirling. In this case, the counterclockwise swirling flow B is on the left side when viewed from the downstream side to the upstream side, which is arranged in the exact opposite direction to the swirling flows A and B shown in FIG. It occurs, and a clockwise swirling flow A is generated on the right side.

Then, these twin-shaped swirling flows are guided to the downstream side while continuing to swirl, so that the swirling can be sustained over a wide range toward the downstream side. That is, in the swirl flow generator 20, a swirl flow having excellent diffusivity is generated and sustained by diffusing (stirring) the reducing agent sprayed through the opening 1a of the exhaust pipe 1 in the exhaust gas purification device 5. It is possible to improve the sex.

Further, the swirl flow generator 20 has an upper end side end portion 20a bent, is arranged along the flow of exhaust gas in the exhaust pipe 1, and extends to a pair of downstream side end portions 20b and 20c. Since the outer diameter side sides 21a and 22a located on the outer diameter side of the surfaces 21 and 22 are configured to be in contact with the inner wall surface of the exhaust pipe 1, the upstream end while suppressing the resistance to the flow of exhaust gas. The exhaust gas divided into left and right by the portion 20a becomes a twin-shaped swirling flow through the region K surrounded by the surfaces 21 and 22 and the inner wall of the exhaust pipe 1, and flows smoothly along the inner wall of the exhaust pipe 1. Become. Therefore, the resistance generated by the exhaust gas purification device 5 becomes small.

In the present embodiment, the case where the swirling flow generator 20 is provided on the upstream side of the reducing agent spraying unit (see FIG. 14A) has been described, but the present invention is not limited to this. The swirl flow generator 20 may be arranged on the downstream side of the reducing agent spraying portion as long as it is on the upstream side of the reducing catalyst 2 (see FIG. 14A).

Further, in the present embodiment, the case where the swirl flow generator 20 is arranged inside the exhaust pipe 1 so as to be symmetrical with respect to the central axis thereof has been described, but the present invention is not limited to this, and the point is exhaust. As long as it is arranged symmetrically with respect to the surface including the central axis of the tube 1, it may be symmetrical in the vertical direction, diagonally, or the like.

According to the swirl flow generator 20 as described above, the exhaust gas flowing on the outer diameter side in the exhaust pipe 1 is divided into both sides (left and right) by the upstream end portion 20a of the swirl flow generator 20 and is on the downstream side. In the process of being guided to and flowing to the downstream end portions 20b and 20c, the inner diameter side is passed through the region K that regulates the flow of exhaust gas surrounded by the surfaces 21 and 22 and the inner wall of the exhaust pipe 1. While being guided to, it flows downstream as a twin-shaped vortex (swirl flow) that rotates in opposite directions along the inner wall of the exhaust pipe 1, so the flow analysis results show the flow velocity in FIG. 8 (a). In addition, it is possible to generate a symmetrical swirling flow having excellent diffusivity by diffusing (stirring) the reducing agent sprayed in the exhaust gas purifying device 5 over a wide range in the exhaust pipe 1.

Moreover, the plate constituting the swirl flow generator 20 is configured so that the outer diameter side sides 21a and 22a located at the outer edge are curved so as to come into contact with the inner wall surface of the exhaust pipe 1, and the upper end side end portion 20a is formed. Since it is arranged along the flow of exhaust gas in the exhaust pipe 1, resistance to the flow of exhaust gas can be suppressed, and a twin-shaped swirling flow is smoothly flowed along the surfaces 21 and 22, and the exhaust gas purification device 5 is provided. The resistance generated by the engine can be reduced. Thus, according to the swirling flow generator 20 of the present embodiment, it is possible to generate a swirling flow having low resistance and excellent diffusivity.

Further, since the diffusivity of the reducing agent sprayed in the exhaust gas purification device 5, that is, the diffusion of the reducing agent in the swirling exhaust gas can be promoted, the reducing agent 2 (see FIG. 14A) can be promoted. Therefore, the reducing agent can be supplied in a more uniform state, and the exhaust gas purification performance can be improved.

Further, since the structure for generating the swirling flow by regulating the flow of the exhaust gas can be configured by the V-shaped plate, the configuration for generating the swirling flow can be simplified.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. The swirl flow generator 30 of the third embodiment according to the present invention is used for a conventionally known exhaust gas purification device 5 (see, for example, FIG. 14A) and the like. Since the exhaust gas purification device 5 is the same as the second embodiment described above except that the structure of the swirl flow generator 30 is different, detailed description of the exhaust gas purification device 5 will be omitted.

The swirl flow generator 30 is in the exhaust pipe 1 as shown in FIGS. 6 (a) to 6 (d) and FIG. 7 in which the corresponding portions corresponding to those in FIGS. 4 (a) to 4 (d) and 5 are designated by the same reference numerals. On the inner diameter side of the bent portion, the exhaust pipe 1 is arranged symmetrically with respect to the surface including the central axis of the exhaust pipe 1 so as to surround the opening 1a, and the exhaust pipe 1 is arranged in a direction orthogonal to the central axis (that is, in the radial direction). It consists of a plate that occludes at least 40% of the cross-sectional area.

Specifically, the swirl flow generator 30 is bent with the upstream side end portion 30a as the top portion, and is formed so as to spread in a V shape toward the pair of downstream side end portions 30b and 30c. Further, in the swirl flow generator 30, the pair of left and right surfaces 31, 32 from the upstream end 30a to the downstream ends 30b, 30c are inner diameter side sides 31a, 32a, which are in contact with the inner wall surface of the exhaust pipe 1, respectively. However, a curved portion is formed along the inner wall of the exhaust pipe 1, and the outer diameter side sides 31b and 31b facing the curved portion are formed substantially linearly, and these outer diameter side sides 31b and 31b and the upstream end portion 30a are formed. The communication portions 31c and 32c connecting the two form a curved portion along the inner wall of the exhaust pipe 1.

Then, the swirl flow generator 30 has the inner diameter side sides 31a and 32a and the communication portions 31c and 32c, respectively, so that the pair of surfaces 31 and 32 are symmetrical with respect to the surface including the central axis thereof inside the exhaust pipe 1. By arranging the and in contact with the inner wall surface of the exhaust pipe 1, these surfaces 31 and 32 surround the perimeter of the opening 1a and close the inner diameter side of the flow path in the bent portion of the exhaust pipe 1. ..

In the swirling flow generator 30 having such a configuration, the exhaust gas flowing in the exhaust pipe 1 is guided separately to the left and right starting from the upstream end portion 30a (see FIGS. 6 (c) and 7 arrows X and Y), and downstream. In the process of flowing toward the side end portions 30b and 30c, the inner diameter side sides 31a and 32a and the communicating portions 31c and 32c are arranged in contact with the inner wall of the exhaust pipe 1 in the exhaust pipe 1 by the surfaces 31 and 32. Since the flow path in the above is narrowed (the flow of exhaust gas is regulated), it is guided from the inner diameter side to the outer diameter side (see arrow Z in FIG. 6 (d)).

In this way, the exhaust gas that has flowed separately to both sides by the upstream end portion 30a passes through the outer diameter side through the region K that regulates the flow of the exhaust gas surrounded by the surfaces 31 and 32 and the inner wall of the exhaust pipe 1. By being guided to, a vortex flow is generated due to the pressure difference between the upstream side and the downstream side of the swirl flow generator 30. Here, since the swirling flow generator 30 has a symmetrical V-shape, twin-shaped swirling flows that rotate in opposite directions along the inner wall of the exhaust pipe 1 (from the downstream side as shown in FIG. 15A). Looking at the upstream side, there is a clockwise swirling flow A on the left side and a counterclockwise swirling flow B on the right side).

Then, these twin-shaped swirling flows are guided to the downstream side while continuing to swirl, so that the swirling can be sustained over a wide range toward the downstream side. That is, in the swirl flow generator 30, the exhaust gas purification device 5 generates and sustains a swirl flow having excellent diffusivity for diffusing (stirring) the reducing agent sprayed through the opening 1a of the exhaust pipe 1. It is possible to improve the sex.

Further, in the swirl flow generator 30, the upper end side end portion 30a is bent, is arranged along the flow of the exhaust gas in the exhaust pipe 1, and extends to the pair of downstream side end portions 30b, 30c. Since the inner diameter side sides 31a and 32a located on the inner diameter side of the surfaces 31 and 32 are configured to be in contact with the inner wall surface of the exhaust pipe 1, the upstream end portion is suppressed while suppressing the resistance to the flow of exhaust gas. The exhaust gas divided into left and right by 30a becomes a twin-shaped swirling flow through the region K surrounded by the surfaces 31 and 32 and the inner wall of the exhaust pipe 1, and flows smoothly along the inner wall of the exhaust pipe 1. .. Therefore, the resistance generated by the exhaust gas purification device 5 becomes small.

In the present embodiment, the case where the swirling flow generator 30 is provided on the upstream side of the reducing agent spraying unit (see FIG. 14A) has been described, but the present invention is not limited to this. The swirl flow generator 30 may be arranged on the downstream side of the reducing agent spraying portion as long as it is on the upstream side of the reducing catalyst 2 (see FIG. 14A).

Further, in the present embodiment, the case where the swirl flow generator 30 is arranged inside the exhaust pipe 1 so as to be symmetrical with respect to the central axis thereof has been described, but the present invention is not limited to this, and the point is exhaust. As long as it is arranged symmetrically with respect to the surface including the central axis of the tube 1, it may be symmetrical in the vertical direction, diagonally, or the like.

According to the swirling flow generator 30 as described above, the exhaust gas flowing in the exhaust pipe 1 is divided into both sides (left and right) by the upstream end portion 30a of the swirling flow generator 30 and guided to the downstream side. In the process of flowing toward the downstream end portions 30b and 30c, the exhaust gas is guided to the outer diameter side through the region K that regulates the flow of exhaust gas surrounded by the surfaces 31 and 32 and the inner wall of the exhaust pipe 1. However, since it flows downstream as a twin-shaped vortex (swirl flow) that rotates in opposite directions along the inner wall of the exhaust pipe 1, the exhaust gas is exhaust gas as shown in the flow analysis result showing the flow velocity in FIG. 8 (b). It is possible to generate a symmetrical swirling flow having excellent diffusivity by diffusing (stirring) the reducing agent sprayed in the purification device 5 over a wide area in the exhaust pipe 1.

Moreover, the plate constituting the swirl flow generator 30 is configured so that the inner diameter side sides 31a and 32a located at the outer edge are curved so as to come into contact with the inner wall surface of the exhaust pipe 1, and the upper end side end portion 30a is exhausted. Since it is arranged along the flow of the exhaust gas in the pipe 1, resistance to the flow of the exhaust gas can be suppressed, and the twin swirling flow is smoothly flowed along the surfaces 31 and 32, and the exhaust gas purification device 5 is used. The generated resistance can be reduced. Thus, according to the swirling flow generator 30 of the present embodiment, it is possible to generate a swirling flow having low resistance and excellent diffusivity.

Further, since the diffusivity of the reducing agent sprayed in the exhaust gas purification device 5, that is, the diffusion of the reducing agent in the swirling exhaust gas can be promoted, the reducing agent 2 (see FIG. 14A) can be promoted. Therefore, the reducing agent can be supplied in a more uniform state, and the exhaust gas purification performance can be improved.

Further, since the structure for generating the swirling flow by regulating the flow of the exhaust gas can be configured by the V-shaped plate, the configuration for generating the swirling flow can be simplified.

<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. First, the overall configuration of the exhaust gas purification device will be described. As shown in FIG. 9, the exhaust gas purification device 100 is incorporated in an exhaust passage for discharging exhaust gas from an engine (not shown). The exhaust gas purification device 100 includes an oxidation catalyst 101, an upstream casing 102, an upstream cap member 103, an upstream connecting member 104, a communication pipe 105, a downstream connecting member 106, and a downstream cap member 107. , A reduction catalyst 108 and a downstream casing 109.

The oxidation catalyst 101 oxidizes the nitrogen compound contained in the exhaust gas. For example, a columnar supported base material on which innumerable gas flow paths are formed along the gas flow direction and a surface of the gas flow path. It has a Pt-Al ₂ O ₃ system catalyst layer coated with.

The upstream casing 102 is a tubular member that houses the oxidation catalyst 101, and in this embodiment, it is composed of a circular stainless steel tube that houses two oxidation catalysts 101 arranged in the flow direction of the exhaust gas. The lower end of the upstream casing 102 in the drawing is an inflow portion 102a (upstream end) into which the exhaust gas from the engine flows. The inflow portion 102a is a portion that connects the exhaust pipe 110 from the engine and the main body portion 102b that houses the oxidation catalyst 101, and is formed in a funnel shape in which the diameter gradually increases toward the oxidation catalyst 101 side. On the other hand, the upper end portion in the figure is the discharge portion 102c (downstream side end portion) from which the exhaust gas that has passed through the oxidation catalyst 101 is discharged. The discharge portion 102c has a circular shape surrounding the oxidation catalyst 101.

The upstream side cap member 103 and the upstream side connecting member 104 are flow path members for guiding the exhaust gas treated by the oxidation catalyst 101 to the communication pipe 105. The exhaust gas is swirled and guided to the communication pipe 105 by the members 103 and 104 and the pressure adjusting plate 111 as a swirling flow generator attached to the upstream cap member 103. Further, the upstream side connecting member 104 is provided with a reducing agent supply port 112 for supplying a reducing agent (for example, urea water). The details of the upstream side cap member 103, the upstream side connecting member 104, and the pressure adjusting plate 111 will be described later.

The communication pipe 105 is arranged between the exhaust downstream side of the oxidation catalyst 101 and the exhaust upstream side of the reduction catalyst 108, and is a flow path member for flowing the exhaust gas treated by the oxidation catalyst 101 to the reduction catalyst 108 side together with the reducing agent. Is. The communication pipe 105 in the present embodiment is made of a stainless steel circular pipe having a diameter smaller than that of the upstream casing 102 and the downstream casing 109. The axial direction of the communication pipe 105 is aligned with the flow direction of the exhaust gas flowing through the upstream casing 102. That is, the exhaust gas treated by the oxidation catalyst 101 by the communication pipe 105, the upstream cap member 103, and the upstream connecting member 104 is folded back toward the inflow portion 102a of the upstream casing 102.

The downstream connecting member 106 and the downstream cap member 107 are members for introducing a mixed gas of the reducing agent and the exhaust gas (exhaust gas treated by the oxidation catalyst 2) that have passed through the communication pipe 105 into the reducing catalyst 108.

The downstream connecting member 106 is different from the upstream connecting member 104 in that the reducing agent supply port 112 is not provided, but the other configurations are the same as those of the upstream connecting member 104. The downstream side cap member 107 is different from the upstream side cap member 103 in that the pressure adjusting plate 111 is not provided, but the other configurations are the same as those of the upstream side cap member 103. Therefore, the description of the upstream side cap member 103 and the upstream side connecting member 104 will be substituted for the description of these members.

The reduction catalyst 108 purifies by reducing nitrogen oxides contained in the mixed gas. For example, a columnar supported base material on which innumerable gas flow paths are formed along the gas flow direction and the columnar supporting base material thereof. _{It has a Ce-Ti-SO 4-} Zr-based catalyst layer coated on the surface of the gas flow path.

The downstream casing 109 is a tubular member that houses the reduction catalyst 108, and in the present embodiment, it is composed of a circular stainless steel tube that houses two reduction catalysts 108 arranged in the flow direction of the exhaust gas. The lower end of the downstream casing 109 in the drawing is an introduction portion 109a (upstream end) into which the mixed gas is introduced, and is covered with the downstream cap member 107. Further, the upper end portion in the drawing of the downstream side casing 109 is a discharge portion 109b (downstream side end portion) for discharging the treated exhaust gas. The discharge portion 109b is formed in a funnel shape in which the diameter gradually decreases toward the downstream side (the side far from the reduction catalyst 108).

Next, the upstream side cap member 103 will be described. The upstream cap member 103 is interposed between the upstream casing 102 and the upstream connecting member 104, bends the flow direction of the exhaust gas treated by the oxidation catalyst 101 at a substantially right angle, and flows the exhaust gas to the upstream connecting member 104. As shown in FIGS. 10 to 12, the upstream cap member 103 has a tubular portion 121, a ceiling portion 122, and an opening tubular portion 123.

The tubular portion 121 is a portion where the end portion of the upstream casing 102 fits, and is made of a short cylindrical member whose inner diameter of the open end is aligned with the outer diameter of the discharge portion 102c of the upstream casing 102. The ceiling portion 122 is a disk-shaped member that closes the end portion of the tubular portion 121 opposite to the open end, and corresponds to the closed portion. As shown in FIG. 11, the ceiling portion 122 is obliquely attached so that the internal space becomes shallower as the distance from the side closer to the opening cylinder portion 123 increases. As a result, the inner surface of the ceiling portion 122 is formed in a slope shape. Then, the tubular portion 121 and the ceiling portion 122 form a cap-shaped member having a shallow bottom.

The opening tubular portion 123 is a portion provided integrally with the tubular portion 121 and the ceiling portion 122, and is connected to the upstream connecting member 104 to guide the exhaust gas. The opening cylinder portion 123 is provided so that the opening 123a at the end faces the side where the opening 123a at the end intersects the axial direction of the upstream casing 102 (the direction of the exhaust gas flowing through the oxidation catalyst 101). As shown in FIG. 10, the opening 123a has a flat shape in the axial direction of the upstream casing 102 (see FIGS. 9 and 11). Specifically, it is an oval shape in which the short side of the rectangle is replaced with a semicircular (curved) shape that is convex outward.

Next, the pressure adjusting plate 111, which is the swirling flow generator according to the fourth embodiment of the present invention, will be described. As shown in FIGS. 9 to 12, a pressure adjusting plate 111 as a swirling flow generator is attached to the inner space of the upstream cap member 103. The pressure adjusting plate 111 is arranged in front of the opening 123a and is a plate-shaped member for creating a pressure difference in the inner space. In the case of the present embodiment, the pressure adjusting plate 111 is formed by using a plate material made of stainless steel.

As shown in FIG. 13, the pressure adjusting plate 111 has a pair of bent portions 111a, a short portion 111b, and a long portion 111c, respectively, and has a symmetrical substantially W shape centered on the central portion 111d. It is bent into a shape (see FIG. 12). Since the lower edge portion 111e faces the end surface of the oxidation catalyst 101 in the mounted state of the upstream cap member 103 (see FIG. 11), the lower edge portion 111e is formed in a straight line. Further, the upper edge portion 111f is formed to be curved in a mountain shape with the bent portion 111a as the top as the upper edge portion 111f abuts on the inner surface of the ceiling portion 122 or the opening cylinder portion 123 (see FIG. 11). reference). Specifically, the bent portion 111a has a higher height than the short portion 111b and the long portion 111c, and the short portion 111b and the long portion 111c have the bent portion 111a according to the slope shape of the ceiling portion 122. The farther away it is, the lower the height.

As shown in FIG. 12, the pressure adjusting plate 111 having such a shape is arranged so that the distance from the oval opening 123a increases from the longitudinal end portion of the oval opening 123a toward the center side. It is installed. The pressure adjusting plate 111 divides the internal space of the upstream cap member 103 into a first portion 103A on the side close to the oval opening 123a and a second portion 103B on the side far from the oval opening 123a.

By interposing the pressure adjusting plate 111 in this way, a pressure difference is applied so that the pressure of the exhaust gas in the first portion 103A becomes lower than the pressure of the exhaust gas in the second portion 103B. Further, a part of the exhaust gas of the second portion 103B passes through the long portion 111c from the bent portion 111a having a high height in the axial direction of the upstream casing 102, and is the top of the long portions 111c, and the height thereof. It flows into the first portion 103A by a path that goes around the low central portion 111d.

Then, by applying a pressure difference between the first portion 103A and the second portion 103B, the exhaust gas flowing into the upstream connecting member 104 can be made into a swirling flow. Further, by regulating the route of the exhaust gas flowing from the second portion 103B to the first portion 103A, the exhaust gas can be efficiently swirled. These points will be described later.

Next, the upstream side connecting member 104 will be described. As shown in FIG. 9, the upstream side connecting member 104 is a member that connects the oval opening 123a of the upstream side cap member 103 and the upstream side end portion of the communication pipe 105. Therefore, the connection portion (cap connection portion 131) of the upstream side connection member 104 with the upstream side cap member 103 is formed in an elongated cylindrical shape having an oval flat flow path inside. On the other hand, the connecting portion (pipe connecting portion 132) of the upstream connecting member 104 with the communicating pipe 105 is formed in a cylindrical shape like the communicating pipe 105.

A bent portion 133 for bending the flow path of the exhaust gas toward the upstream end of the communication pipe 105 is provided between the cap connecting portion 131 and the pipe connecting portion 132. Inside the bent portion 133, a narrowed flow path whose flow path width is narrowed so as to approach the communication pipe 105 is formed. The cross-sectional shape of this narrowed flow path changes from an oval shape to a circular shape from the upstream side to the downstream side. In this case, since the downstream end of the narrowed flow path has a tapered surface, the exhaust gas flowing through the narrowed flow path tends to generate a swirling flow by flowing along the tapered surface.

Further, as shown in FIGS. 9 and 11, a reducing agent supply port 112 is provided in the bent portion 133. The reducing agent supply port 112 is for supplying the reducing agent to the exhaust gas after being treated with the oxidation catalyst 101, and is provided at a position facing the exhaust upstream end of the communication pipe 105. For example, the supply nozzle 134 shown by the virtual line in FIG. 11 is inserted into the reducing agent supply port 112, and the reducing agent is supplied to the exhaust gas flowing through the upstream connecting member 104 through the supply nozzle 134. The supplied reducing agent flows through the communication pipe 105 while being mixed with the exhaust gas.

In the exhaust gas purification device 100 having the above configuration, the exhaust gas from the engine flows in from the inflow portion 102a. Then, nitric oxide contained in the exhaust gas is oxidized by the oxidation catalyst 101 to become nitrogen dioxide. The exhaust gas treated by the oxidation catalyst 101 is introduced into the communication pipe 105 through the upstream cap member 103 and the upstream connecting member 104. At that time, the exhaust gas becomes a swirling flow and is mixed with the reducing agent supplied through the reducing agent supply port 112 of the upstream connecting member 104. The mixed gas that has passed through the communication pipe 105 is introduced into the reduction catalyst 108 through the downstream connecting member 106 and the downstream cap member 107. The reduction catalyst 108 reduces nitrogen dioxide contained in the mixed gas to nitrogen. The mixed gas treated with the reduction catalyst 108 is released into the atmosphere through the release unit 109b.

In the exhaust gas purification device 100, since the pressure adjusting plate 111 is arranged in the internal space of the upstream cap member 103, the exhaust gas can be swirled and introduced into the communication pipe 105. Further, since the internal space of the upstream side connecting member 104 is configured to narrow the flow path width as it approaches the communication pipe 105, the exhaust gas can be easily swirled in this respect as well. These points will be described below.

The exhaust gas that has passed through the oxidation catalyst 101 flows through the internal space of the upstream cap member 103 toward the oval opening 123a. Further, the flow direction of the exhaust gas is regulated by the pressure adjusting plate 111, and a large amount of the exhaust gas flows into the oval opening 123a from an oblique direction. At this time, since the cross-sectional area of the flow path through which the exhaust gas passes gradually becomes narrower, the first range from the oxidation catalyst 101 to the oval opening 123a, the second range corresponding to the upstream connecting member 104, and the communication pipe. When divided into the third range corresponding to 105, the flow velocity in the first range is the slowest, accelerated in the second range, and further accelerated in the third range.

Further, with the pressure adjusting plate 111 as a boundary, a large pressure difference occurs between the first portion 103A on the oval opening side and the second portion 103B on the opposite side. When such a large pressure difference occurs in the vicinity of the pressure adjusting plate 111, the exhaust gas having an increased flow velocity flows around along the pressure adjusting plate 111. Then, when the exhaust gas flows into the surface of the pressure adjusting plate 111 on the oval opening side, a large amount of the exhaust gas flows along the inner surface of the pressure adjusting plate 111 and the opening cylinder portion 123. As a result, the exhaust gas becomes a swirling flow and flows inside the narrowed flow path of the upstream connecting member 104 and the communication pipe 105. At that time, since the exhaust gas flows along the tapered surface in the narrowed flow path, the swirling flow can be further strengthened.

As described above, in the pressure adjusting plate 111 which is the swirling flow generator of the present embodiment, the exhaust gas purifying device 100 can generate the swirling flow in the exhaust gas flowing through the communication pipe 105, so that the exhaust gas is supplied through the reducing agent supply port 112. The resulting reducing agent can be mixed in a state of being diffused with respect to the exhaust gas (a state closer to homogeneity). As a result, the reactivity when reducing nitrogen dioxide to nitrogen with the reduction catalyst 108 can be enhanced, and the exhaust gas purification performance can be enhanced.

As described above, according to the pressure adjusting plate 111, which is the swirling flow generator of the present embodiment, the exhaust gas purifying device 100 is arranged in front of the opening 123a in the inner space of the upstream cap member 103. Since a pressure difference is generated between the space on the opening side and the space on the opposite side, this pressure difference can be used to generate a swirling flow in the exhaust gas in the vicinity of the opening. That is, the configuration for generating a swirling flow can be simplified.

Further, the pressure adjusting plate 111 is arranged so that the distance from the oval opening 123a increases from one end side to the other end side in the longitudinal direction of the flat oval opening 123a in the exhaust gas purification device 100. Therefore, the flow direction of the exhaust gas toward the oval opening 123a can be regulated by the pressure adjusting plate 111. As a result, it is possible to easily generate a swirling flow.

In addition, since the upstream connecting member 104 that forms the constricted flow path is provided between the opening tube portion 123 and the communication pipe 105, it is possible to easily generate a swirling flow by passing through the constricted flow path. it can.

Further, since the reducing agent supply port 112 is provided at a position facing the exhaust upstream end of the communication pipe 105, the reducing agent can be supplied to the exhaust gas that has become a swirling flow.

The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be modified and improved without departing from the spirit of the present invention, and the present invention includes its equivalents. For example, it may be configured as follows.

Regarding the pressure adjusting plate 111, in the above-described embodiment, the bent portion 111a is arranged in the vicinity of the oval opening 123a, but the shape is not limited to this. For example, the bent portion 111a may be arranged on the side farther from the oval opening 123a than in the above-described embodiment. In short, the pressure adjusting plate 111 may be a plate-shaped member that causes a pressure difference in the inner space of the upstream cap member 103.

Further, regarding the opening cylinder portion 123 included in the upstream cap member 103, the opening cylinder portion 123 in the above-described embodiment is for partitioning the flat elliptical opening 123a, but may be a rectangular opening or a hexagonal opening. .. In short, it may be a flat opening.

Further, regarding the reducing agent, in the above-mentioned embodiment, the urea aqueous solution is used as the reducing agent, but the reducing agent is not limited thereto. For example, it may be an aqueous ammonia solution. However, light oil containing hydrocarbon as a main component may be used.

1,11 ... Exhaust pipe 2,108 ... Reducing catalyst 3,134 ... Reducing agent spray nozzle 5,100 ... Exhaust gas purification device 10, 20, 30 ... Swirling flow generator 10a, 20a, 30a ... Upstream end 10b, 10c , 20b, 20c, 30b, 30c ... Downstream end 10d, 10e ... Upper side 21,22,31,32 ... Surface 21a, 22a, 31b, 32b ... Outer diameter side 21b, 21b, 31a, 32a ... Inner diameter side 31c, 32c ... Communication part K ... Region 101 ... Oxidation catalyst 102 ... Upstream side casing 102a ... Inflow part 102b ... Main body part 102c ... Exhaust part 103 ... Upstream side cap member 103A ... First part 103B ... Second part 104 ... Upstream side Connecting member 105 ... Communication pipe 106 ... Downstream connecting member 107 ... Downstream cap member 108 ... Reducing catalyst 109 ... Downstream casing 109a ... Introducing part 109b ... Discharging part 111 ... Pressure adjusting plate (swirl flow generator)
111a ... Bending part 111b ... Short part 111c ... Long part 111d ... Central part 111e ... Lower edge part 111f ... Upper edge part 112 ... Reducing agent supply port 121 ... Cylindrical part 122 ... Ceiling part (closed part)
123 ... Opening cylinder 123a ... Oval opening (end opening)
131 ... Cap connection part of upstream connection member 132 ... Pipe connection part of upstream connection member 133 ... Bending part of upstream connection member 134 ... Supply nozzle

Claims (6)

An exhaust pipe through which exhaust gas flows, a reduction catalyst provided in the exhaust pipe for reducing and purifying nitrogen oxides contained in the exhaust gas, and a reducing agent supply means for injecting and supplying a reducing agent to the exhaust gas flowing upstream of the reduction catalyst. An exhaust gas purifying device including, which is a swirling flow generator that is arranged upstream of the reduction catalyst in the exhaust pipe and generates a swirling flow in the exhaust gas.
It comprises a plate that is symmetrically arranged in the exhaust pipe with respect to a surface including the central axis of the exhaust pipe and closes at least 40% of the cross-sectional area of the exhaust pipe in a direction orthogonal to the central axis .
The plate has a V-shape with its upstream end bent and widened toward a pair of downstream ends.
The plate is characterized in that at least one of the upper and lower sides of each of the pair of left and right surfaces from the upstream end to the downstream end is curved along the inner wall of the exhaust pipe. Swirling flow generator. The swirling flow generator according to claim 1, wherein the plate is arranged along an inner wall surface on the outer diameter side or the inner diameter side in the exhaust pipe at a portion where the exhaust pipe is bent. An exhaust pipe through which exhaust gas flows, a reduction catalyst provided in the exhaust pipe for reducing and purifying nitrogen oxides contained in the exhaust gas, and a reducing agent supply means for injecting and supplying a reducing agent to the exhaust gas flowing upstream of the reduction catalyst. An exhaust gas purification device including, which is a swirl flow generator that is arranged upstream of the reduction catalyst in the exhaust pipe and generates a swirl flow in the exhaust gas.
It comprises a plate that is symmetrically arranged in the exhaust pipe with respect to a surface including the central axis of the exhaust pipe and closes at least 40% of the cross-sectional area of the exhaust pipe in a direction orthogonal to the central axis .
A swirling flow generator characterized in that the plate is arranged along an inner wall surface on the outer diameter side or the inner diameter side in the exhaust pipe at a portion where the exhaust pipe is bent. The swirling flow generator according to claim 3 , wherein the plate has a V-shape in which the upstream end is bent and spreads toward a pair of downstream ends. The exhaust gas purification device is
A tubular part whose one end fits on the upstream side of the exhaust pipe,
A cap member having a cap shape having a closed portion that closes the other end of the tubular portion, and having an opening for flowing the exhaust gas to the reduction catalyst arranged on the downstream side of the exhaust pipe toward the side. And, with more
The swirling flow generator according to any one of claims 1 to 4, wherein the plate is arranged in front of the opening in the inner space of the cap member. The opening has a flat shape in the flow direction of the exhaust gas.
The swirling flow generation according to claim 5, wherein the upstream end of the plate is bent and a pair of downstream ends extending toward both ends in the longitudinal direction of the opening are arranged. Equipment .

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