JP6456859B2 - Exhaust gas purification device - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus in which a mixer for mixing urea water injected into an exhaust gas passage from a urea water supply apparatus with exhaust gas is disposed upstream of a NOx purification catalytic converter having a cylindrical casing.

  A urea water supply device for supplying urea water is connected at right angles to the side wall of a cylinder that forms part of the exhaust gas passage upstream of the catalytic converter filled with the NOx purification catalyst, and a mixer is connected to the exhaust gas in the cylinder An exhaust gas purification apparatus configured to include a plurality of wall portions that extend in parallel along the exhaust gas flow direction of the passage and have a surface area that increases with distance from the urea water supply apparatus is disclosed in Patent Document 1, for example. Are known.

JP2015-218615A

  However, in the one disclosed in Patent Document 1, it may be difficult to efficiently mix the urea water and the exhaust gas depending on the fluctuation of the exhaust gas amount.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust gas purifying apparatus capable of effectively mixing urea water and exhaust gas with a mixer regardless of fluctuations in the amount of exhaust gas.

In order to achieve the above object, according to the present invention, a mixer for mixing urea water injected into an exhaust gas passage from a urea water supply device with exhaust gas is disposed upstream of a NOx purification catalytic converter having a cylindrical casing. In the exhaust gas purifying apparatus, the mixer is connected to the casing so as to be connected to the casing and has a cylindrical peripheral wall provided with a urea water injection port connected to the urea water supply device at one place in the circumferential direction, and the NOx A downstream partition wall having a lead-out hole that opens toward the upstream central portion of the purification catalytic converter and having an outer periphery fixed to the peripheral wall downstream from the urea water injection port , and along a circumferential direction of the lead-out hole a guide wall so as to surround a part erected on the downstream side partition wall, said peripheral wall of said portion of exhaust gas to the urea water injection opening is arranged to be introduced into the mixer and An exhaust gas collecting guide portion that collects between the guide walls, and the guide wall is disposed to face the urea water injection port, and is formed in a shape that opens the opposite side to the urea water injection port. The exhaust gas collecting guide portion has an outer periphery fixed to the peripheral wall on the upstream side of the urea water injection port, one side faces with a gap between the downstream partition walls, and the upstream side of the mixer. An upstream side partition facing the other side of the exhaust gas passage; and an inflow hole provided in the upstream side partition so as to penetrate a part of the upstream side partition, wherein the inflow hole is provided with the urea water injection port The space between the peripheral wall of the portion and the guide wall is opened toward the space so that the exhaust gas gathers, and the central axis of the inflow hole is connected to the central axis of the urea water injection port the that is substantially orthogonal in space 1 And features.

The present invention, in addition to the first feature, the downstream is side partition wall, said guide wall the downstream partition wall a mixture of the exhaust gas before Symbol urea water and in a position facing the open end of A guide portion that leads toward the central outlet hole is provided, and the guide portion is formed to extend from the outer peripheral portion of the downstream-side partition wall toward the upstream end central portion of the NOx purification catalytic converter. This is the second feature.

The present invention, in addition to the first or second aspect, before Symbol inflow hole, the third being formed in a fan shape along a portion the outer surface of the guide wall.

  The secondary catalytic converter 13 of the embodiment corresponds to the NOx purification catalytic converter of the present invention.

According to the first feature of the present invention, the exhaust gas flowing into the mixer is gathered in the space between the peripheral wall and the guide wall of the portion where the urea water injection port is provided by the action of the exhaust gas collecting guide portion. Exhaust gas and urea water are quickly and efficiently mixed by spraying urea water in a minimum range from the urea water injection port toward the portion (the space) . In addition, the urea water changes to ammonia in the process in which the exhaust gas mixed with urea water passes around the guide wall to the outlet hole side, and the time for changing from urea water to ammonia can be earned. It flows to the center of the upstream end of the NOx purification catalytic converter through the lead-out hole, and urea water and exhaust gas can be effectively mixed with a mixer regardless of fluctuations in the amount of exhaust gas, and ammonia and exhaust gas can be mixed with the NOx purification catalytic converter. Can be efficiently guided to.

Further, according to the second feature of the present invention, the exhaust gas that is mixed with urea water and passes around the guide wall to the outlet hole side is guided to the outlet hole at the center of the downstream partition wall by the guide part, and ammonia is The contained exhaust gas can flow smoothly to the central portion of the upstream end of the NOx purification catalytic converter.

Further according to the third aspect of the present invention, a flow-in hole is so formed in a fan shape along a portion the outer surface of the guide wall, to increase the opening area of the inlet hole along a portion the outer surface of the guide wall , Can contribute to the reduction of distribution resistance.

It is a figure which shows the exhaust system of a diesel engine. It is a principal part longitudinal section top view of an exhaust gas purification apparatus. It is a disassembled perspective view of a mixer.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. First, in FIG. 1, an exhaust system 11 of a diesel engine E is a primary catalyst for oxidizing and removing CO and HC in exhaust gas. A converter 12, a secondary catalytic converter 13 disposed downstream of the primary catalytic converter 12, and a mixer 14 are provided. The mixer 14 distributes an exhaust gas flowing in an exhaust gas passage 15 included in the exhaust system 11. Is disposed between the primary and secondary catalytic converters 12 and 13 so as to be disposed upstream of the secondary catalytic converter 13, and a urea water supply device that supplies urea water to the mixer 14. 17 is connected.

  Referring also to FIG. 2, the secondary catalytic converter 13 is a NOx purification catalytic converter, in which a honeycomb structured ceramic 18 supporting a catalyst is supported by a cylindrical casing 19 via a mat 20. It works to reduce and remove NOx in the exhaust gas passing through.

  The mixer 14 mixes the urea water supplied from the urea water supply device 17 in the exhaust gas passage 15 with the exhaust gas and guides it to the secondary catalytic converter 13 side, and is derived from the primary catalytic converter 12. The exhaust gas discharged from the mixer 14 passes through a first exhaust pipe 21 whose upstream end is connected to the primary catalytic converter 12 and a second exhaust pipe 22 connecting the first exhaust pipe 21 and the mixer 14. The first and second exhaust pipes 21 and 22 form part of the exhaust gas passage 15 respectively. The second exhaust pipe 22 is fitted to the tapered end portion 22a having a larger diameter toward the mixer 14 and the downstream end portion of the first exhaust pipe 21 coaxially connected to the small diameter end of the tapered portion 22a. The upstream connection pipe part 22b to be connected and the downstream connection pipe part 22c coaxially connected to the large diameter end of the taper part 22a are integrally formed.

Referring also to FIG. 3, the mixer 14 is connected to the casing 19 so as to be connected to the cylindrical casing 19 included in the secondary catalytic converter 13 and is connected to the urea water supply device 17 and the urea water injection port 23. Has a cylindrical peripheral wall 24 provided at one place in the circumferential direction, and a lead-out hole 25 that opens toward the upstream central portion of the secondary catalytic converter 13, and the downstream side of the urea water injection port 23. and the downstream-side partition wall 29a which outer periphery is fixed to the peripheral wall 24, the urea water injection port 23 opposite to surround a portion in the circumferential direction of the outlet hole 25 being formed in an open shape of the downstream partition wall and The guide wall 26 erected on 29a and the exhaust gas introduced into the mixer 14 are gathered between the peripheral wall 24 and the guide wall 26 at a portion where the urea water injection port 23 is provided. And a flue gas collection guide portion 27.

The mixer 14 includes a first dish-shaped body 28, a second dish-shaped body 29 to which the guide wall 26 is welded, and a cylindrical body 30 that are coupled to each other. The first dish-like body 28 has one side face (lower side face in FIG. 2) facing the downstream partition wall 29a and the other side face (in FIG. 2) in the exhaust gas passage 15 upstream from the mixer 14. The first cylindrical portion 28b is integrally connected to the outer periphery of the disk-shaped upstream partition wall 28a facing the upper side as viewed, and the open end portion of the first cylindrical portion 28b is the second exhaust pipe 22. Are fitted and welded to the downstream connection pipe portion 22c. The second dish-like body 29 is formed by integrally connecting a second cylindrical portion 29b to the outer periphery of a disk-shaped downstream partition wall 29a facing the upstream partition wall 28a from the secondary catalytic converter 13 side, A part of the first cylindrical portion 28a is fitted and welded to the open end portion of the second cylindrical portion 29b. The cylindrical body 30 is formed in a cylindrical shape by fitting the second cylindrical portion 29b over the entire length thereof, and one end thereof is formed on the outer periphery of the first cylindrical portion 28b together with the second cylindrical portion 29b. Welded. The upstream end of the casing 19 is fitted into the other end of the cylindrical body 30, and the other end of the cylindrical body 30 is welded to the outer periphery of the casing 19.

The peripheral wall 24 of the mixer 14 includes a first cylindrical portion 28 b, a second cylindrical portion 29 b, and the cylindrical body 30, and urea water having one end connected to the urea water supply device 17. The other end portion of the supply pipe 31 penetrates the cylindrical body 30 and the second cylindrical portion 29b, which are part of the peripheral wall 24, between the downstream partition wall 29a and the upstream partition wall 28a. The other end opening of the urea water supply pipe 31 is welded to one location in the circumferential direction of the outer periphery of the 30 and serves as the urea water injection port 23. That is, the downstream partition wall 29 a is fixed to the peripheral wall 24 at the downstream side of the urea water injection port 23, and the upstream partition wall 28 a is connected to the peripheral wall 24 at the upstream side of the urea water injection port 23. Is fixed.

In the central portion of the downstream partition wall 29a, a lead-out hole 25 that opens toward the upstream central portion of the secondary catalytic converter 13 is provided. In this embodiment, the guide wall 26 is formed in a U shape with the opposite side to the urea water injection port 23 open, and is integrated with the end of the guide wall 26 on the downstream partition wall 29a side. The guide wall 26 erected on the downstream side partition wall 29a by welding the formed flange part 26a to the downstream side partition wall 29a is disposed so as to surround a part along the circumferential direction of the outlet hole 25. .

In the exhaust gas collecting guide portion 27, the upstream partition wall 28a is provided with an inflow hole 32 that opens toward the space S between the peripheral wall 24 and the guide wall 26 in a portion where the urea water injection port 23 is provided. The inflow hole 32 is formed in a fan shape along a part of the outer surface of the guide wall 26. Moreover, the central axis of the inflow hole 32 is substantially orthogonal to the central axis of the urea water injection port 23 in the space S, as is apparent from the description of FIGS. 2 and 3.

Also on the downstream side partition wall 29a at the open end side of the guide wall 26, the guide portion 33 of a mixture of urea water and the exhaust gas guided toward the downstream side partition wall 29a central outlet hole 25 is Ru provided. That is , the guide portion 33 is located at a position facing the open end of the guide wall 26 and extends from the outer peripheral portion of the downstream partition wall 29a to be inclined toward the central portion of the upstream end of the secondary catalytic converter 13. It is formed.

Next, the operation of this embodiment will be described. The mixer 14 is connected to the casing 19 so as to be connected to the cylindrical casing 19 of the secondary catalytic converter 13 and is connected to the urea water supply device 17 and the urea water injection port 23. Has a cylindrical peripheral wall 24 provided at one place in the circumferential direction, and a lead-out hole 25 that opens toward the upstream central portion of the secondary catalytic converter 13, and the downstream side of the urea water injection port 23. and the downstream-side partition wall 29a which outer periphery is fixed to the peripheral wall 24, the downstream-side partition wall 29a so as to surround a portion in the circumferential direction of the outlet hole 25 being formed in a shape having an open side opposite to the urea water injection port 23 a guide wall 26 provided upright in the space S between the peripheral wall 24 and the guide wall 26 of the portion where the urea water injection port 23 of the exhaust gas introduced into the mixer 14 is provided And a flue gas collection guide 27 for collection, in particular an exhaust gas collection guide 27, one side surface across the gap on the downstream side partition wall 29a is the outer circumference wall 24 on the upstream side of the urea water injection port 23 is fixed Are provided with an upstream partition wall 28a facing the exhaust gas passage 15 upstream of the mixer 14 and an inflow hole 32 provided in the upstream partition wall 28a so as to penetrate part of the upstream partition wall 28a. Moreover, the central axis of the inflow hole 32 is substantially orthogonal to the central axis of the urea water injection port 23 in the space S as described above.

Thus, the exhaust gas flowing into the mixer 14 flows into the space S between the peripheral wall 24 and the guide wall 26 of the portion where the urea water injection port 23 is provided by the action of the exhaust gas collecting guide portion 27 , and gathers. The urea water is sprayed in a minimum range from the urea water injection port 23 toward the exhaust gas collecting portion (that is, the space S) , whereby the exhaust gas and the urea water are quickly and efficiently mixed. Moreover, the urea water changes to ammonia in the process in which the exhaust gas mixed with the urea water passes around the guide wall 26 to the outlet hole 25 side, and it is possible to earn time for changing from urea water to ammonia. Ammonia flows through the outlet hole 25 to the central portion of the upstream end of the secondary catalytic converter 13, and the urea water and the exhaust gas can be effectively mixed by the mixer 14 regardless of the fluctuation of the exhaust gas amount. The exhaust gas can be efficiently guided to the secondary catalytic converter 13.

In addition, a guide portion 33 is provided in the downstream partition wall 29a on the open end side of the guide wall 26 to guide the air-fuel mixture of the urea water and the exhaust gas toward the outlet hole 25 in the center of the downstream partition wall 29a. The exhaust gas that passes through the periphery of the guide wall 26 to the outlet hole 25 side while being mixed is guided to the outlet hole 25 by the guide portion 33, so that the exhaust gas containing ammonia is smoothly supplied to the center of the upstream end of the secondary catalytic converter 13. It can flow.

Further, the exhaust gas collecting guide portion 27 is located upstream of the urea water injection port 23, and the peripheral wall 24 at a portion where the urea water injection port 23 is provided in the upstream partition wall 28a whose outer periphery is fixed to the peripheral wall 24. An inflow hole 32 that opens toward the space S between the guide walls 26 is provided, and the inflow hole 32 is formed in a sector shape along a part of the outer surface of the guide wall 26. It is possible to increase the opening area of the inflow hole 32 along a part of the outer surface and contribute to the reduction of the flow resistance.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, in the above-described embodiment, the guide wall 26 is formed in a U shape with the opposite side to the urea water injection port 23 open, but may be V-shaped or U-shaped.

13 ... NOx purification catalytic converter secondary catalytic converter 14 ... mixer 15 ... exhaust gas passage 17 ... urea water supply device 19 ... casing 23 ... urea water injection port 24 ... Peripheral wall 25 ... leading hole 26 ... guide wall 27 ... exhaust gas collection guide part
28a ·· Upstream partition wall 29a ·· Downstream partition wall 32 ··· Inflow hole 33 ··· Guide part
S ... Space

Claims (3)

The mixer (14) that mixes urea water injected from the urea water supply device (17) into the exhaust gas passage (15) with the exhaust gas is upstream of the NOx purification catalytic converter (13) having a cylindrical casing (19). In the exhaust gas purification device disposed in
The mixer (14) is connected to the casing (19) so as to be continuous with the casing (19), and a urea water injection port (23) connected to the urea water supply device (17) is provided at one place in the circumferential direction. It has a cylindrical peripheral wall (24) and a lead-out hole (25) opening toward the upstream central portion of the NOx purification catalytic converter (13), and the downstream side of the urea water injection port (23). the peripheral wall (24) and the downstream partition wall (29a) of the outer periphery is fixed to the front Symbol outlet hole (25) in the circumferential direction along so as to surround a portion the downstream partition wall (29a) to the erected by the guide wall ( and 26), the mixer (the peripheral wall portion 14) of the exhaust gas to be introduced into the urea water injection port (23) is provided (24) and said guide wall (26) an exhaust gas set guide portions which collectively between (27) For example,
The guide wall (26) is disposed so as to face the urea water injection port (23), and is formed in a shape opening the opposite side to the urea water injection port (23),
The exhaust gas collecting guide portion (27) has an outer periphery fixed to the peripheral wall (24) on the upstream side of the urea water injection port (23), and one side faces the gap on the downstream partition wall (29a). And an upstream partition wall (28a) facing the exhaust gas passage (15) upstream from the mixer (14), and the upstream partition wall (28a) so as to penetrate a part of the upstream partition wall (28a). And an inflow hole (32) provided in the
In the inflow hole (32), a space (S) between the peripheral wall (24) and the guide wall (26) in a portion where the urea water injection port (23) is provided is an exhaust gas collecting part. Opening toward the space (S), the center axis of the inflow hole (32) is substantially orthogonal to the center axis of the urea water injection port (23) in the space (S). Exhaust gas purification device. Wherein the downstream partition wall (29a), said guide wall (26) the downstream partition wall (29a) the center of the lead-out hole of the air-fuel mixture before Symbol urea water and the exhaust gas in a position facing the open end of the ( 25), a guide portion (33) is provided to guide the guide portion (33) from the outer peripheral portion of the downstream partition wall (29a) toward the upstream end central portion of the NOx purification catalytic converter (13). The exhaust gas purifying apparatus according to claim 1, wherein the exhaust gas purifying apparatus is formed to be inclined and extended . Before SL inlet (32), the exhaust gas purifying apparatus according to claim 1 or 2, characterized in that it is formed in a fan shape along a portion the outer surface of the guide wall (26).

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