Mixing chamber assembly and exhaust gas aftertreatment package

Abstract

A mixing chamber assembly includes a mixing chamber housing and a mixing tube assembly mounted in the mixing chamber housing. The mixing chamber housing is provided with a first chamber and a second chamber. The mixing tube assembly includes a cyclone tube in the first chamber and a connecting tube in the second chamber. The cyclone tube is provided with a first inner chamber, a plurality of cyclone vanes and air inlets corresponding to the cyclone vanes. The mixing tube assembly further includes an arc plate in the first chamber and partially surrounding the cyclone vanes, so that the exhaust gas needs to bypass the arc plate to enter the cyclone tube from the air inlets. In this way, a large amount of exhaust gas is prevented from directly rushing to the cyclone tube, thereby causing uneven air flow distribution and improving the ability to resist urea crystallization. The present application also relates to an exhaust gas aftertreatment package including the above mixing chamber assembly.

Description

TECHNICAL FIELD

[0001] The application relates to a mixing cavity assembly and an exhaust gas aftertreatment package, and belongs to the technical field of engine exhaust gas aftertreatment. BACKGROUND

[0002] Research shows that the uniformity of ammonia distribution in the pipeline of an exhaust gas aftertreatment system (for example, a selective catalytic reduction system, SCR system) has an important influence on the overall performance and durability of the system. Long-term uneven distribution of ammonia can cause uneven aging of the catalyst, thereby affecting the overall performance of the catalyst. In addition, uneven distribution of urea droplets can cause local pipe wall or mixing structure temperature to be too low, forming crystals, and in severe cases, blocking the exhaust pipe and causing the engine power performance to decrease. SUMMARY

[0003] The application aims to provide a mixing cavity assembly and an exhaust gas aftertreatment package with good resistance to urea crystallization.

[0004] To achieve the above-mentioned purpose, the application adopts the following technical scheme: a mixing cavity assembly, comprising a mixing cavity shell and a mixing pipe assembly installed in the mixing cavity shell, the mixing cavity shell is provided with a first opening for communicating with a first aftertreatment carrier assembly, a second opening for communicating with a second aftertreatment carrier assembly, a first cavity communicating with the first opening, and a second cavity communicating with the second opening; the mixing pipe assembly comprises a cyclone pipe in the first cavity and a connecting pipe in the second cavity; the cyclone pipe is provided with a first inner cavity, a plurality of cyclone fins, and an airflow inlet corresponding to the cyclone fins, the first inner cavity communicates with the first cavity through the airflow inlet, the connecting pipe is provided with a second inner cavity communicating with the first inner cavity, and the second inner cavity communicates with the second cavity; the mixing pipe assembly further comprises an arc-shaped plate located in the first cavity and partially surrounding the cyclone fins, so that the exhaust gas needs to bypass the arc-shaped plate to enter the cyclone pipe from the airflow inlet.

[0005] As a further improved technical scheme of the application, the cross section of the arc-shaped plate is C-shaped.

[0006] As a further improved technical scheme of the application, the center axis of the arc-shaped plate is parallel to the center axis of the cyclone pipe, and the mixing cavity assembly comprises an arc-shaped airflow passage between the arc-shaped plate and the cyclone pipe.

[0007] As a further improved technical scheme of the application, the mixing cavity shell is provided with a mounting seat for mounting a urea nozzle, and the urea nozzle is used to spray atomized urea droplets into the cyclone pipe.

[0008] As a further improved technical scheme of the present application, the mixing cavity shell is provided with a first mounting surface close to the mounting seat and located on the inner side of the first cavity, one end of the arc-shaped plate is provided with a first mounting claw fixed on the first mounting surface and a slot located on the side of the first mounting claw, and the slot is communicated with the arc-shaped airflow passage.

[0009] As a further improved technical scheme of the present application, the mixing cavity shell is provided with a partition plate located between the first cavity and the second cavity, and the other end of the arc-shaped plate is provided with a second mounting claw fixed on the partition plate.

[0010] As a further improved technical scheme of the present application, the mixing cavity assembly comprises an end assembly located in the second cavity and at the bottom of the connecting pipe, and the end assembly comprises a bottom wall, a peripheral wall extending upward from the periphery of the bottom wall, and a buffer cavity surrounded by the bottom wall and the peripheral wall.

[0011] As a further improved technical scheme of the present application, the peripheral wall is provided with a first side wall facing the second aftertreatment carrier assembly, and the first side wall is provided with a plurality of first airflow perforations for allowing airflow to flow through.

[0012] As a further improved technical scheme of the present application, the mixing pipe assembly comprises a urea breaking pipe located in the first inner cavity and the second inner cavity, the urea breaking pipe extends along an axial direction, and a plurality of urea breaking grooves are arranged on the outer wall of the urea breaking pipe, and the length of the urea breaking grooves along the axial direction is greater than the width of the urea breaking grooves along a radial direction perpendicular to the axial direction.

[0013] The present application also discloses an exhaust gas aftertreatment package, which comprises a first aftertreatment carrier assembly, a second aftertreatment carrier assembly, a third aftertreatment carrier assembly located upstream of the first aftertreatment carrier assembly, and a mixing cavity assembly connecting the first aftertreatment carrier assembly and the second aftertreatment carrier assembly, wherein the first aftertreatment carrier assembly is a diesel particulate filter, the second aftertreatment carrier assembly is a selective catalytic reduction agent, the third aftertreatment carrier assembly is a diesel oxidation catalyst, and the mixing cavity assembly is the mixing cavity assembly as described above.

[0014] Compared with the prior art, the arc-shaped plate partially surrounds the rotational flow piece, so that the exhaust gas needs to bypass the arc-shaped plate to enter the rotational flow pipe from the airflow inlet. In this way, the airflow flowing from the first opening directly hits the rotational flow pipe is avoided, so that the airflow distribution is uniform, and the ability to resist urea crystallization is improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view of the exhaust gas aftertreatment package of the present application.

[0016] Figure 2 is a perspective view of the mixing chamber assembly of the present application in one embodiment.

[0017] Figure 3 is a partial exploded view of Figure 2

[0018] Figure 4 is a perspective view of the mixing chamber assembly of the present application in one embodiment. Figure 2

[0019] Figure 5 is a perspective exploded view of Figure 4

[0020] Figure 6 is a front view of the urea break pipe of Figure 5

[0021] is a cross-sectional view along line A-A of Figure 7 Figure 2

[0022] Figure 8 Figure 2 DETAILED DESCRIPTION

[0023] Referring to Figure 1 , the present application discloses a tail gas aftertreatment package, which comprises a first aftertreatment carrier assembly 1, a second aftertreatment carrier assembly 2, a third aftertreatment carrier assembly 3 located upstream of the first aftertreatment carrier assembly 1, and a mixing chamber assembly 4 connecting the first aftertreatment carrier assembly 1 and the second aftertreatment carrier assembly 2. In one embodiment of the present application, the first aftertreatment carrier assembly 1 is a diesel particulate filter (DPF), the second aftertreatment carrier assembly 2 is a selective catalytic reduction (SCR), and the third aftertreatment carrier assembly 3 is a diesel oxidation catalyst (DOC).

[0024] The mixing chamber assembly 4 comprises a mixing chamber housing 5 and a mixing pipe assembly 6 installed in the mixing chamber housing 5. The mixing chamber housing 5 is provided with a first opening 51 for communicating with the first aftertreatment carrier assembly 1, a second opening 52 for communicating with the second aftertreatment carrier assembly 2, a first chamber 53 communicating with the first opening 51, a second chamber 54 communicating with the second opening 52, and a partition 55 located between the first chamber 53 and the second chamber 54.

[0025] ​​​​​​​The mixing tube assembly 6 includes a swirl tube 61 located in the first cavity 53, a connecting tube 62 located in the second cavity 54, an arc-shaped plate 63 located in the first cavity 53 and partially surrounding the swirl tube 61, a urea crushing tube 64 installed in the swirl tube 61 and the connecting tube 62, and a urea crushing plate 65 fixed to the bottom of the connecting tube 62 and located at the bottom of the urea crushing tube 64.

[0026] The swirling tube 61 is provided with a first inner cavity 611, a plurality of swirling vanes 612, and an airflow inlet 613 corresponding to the swirling vanes 612. The first inner cavity 611 is connected to the first cavity 53 through the airflow inlet 613. The connecting tube 62 is provided with a second inner cavity 621 connected to the first inner cavity 611, and the second inner cavity 621 is connected to the second cavity 54. The wall of the connecting tube is provided with a plurality of airflow perforations 622. The arc-shaped plate 63 partially surrounds the swirling vanes 612, so that the exhaust gas from the first opening 51 must bypass the arc-shaped plate 63 before entering the swirling tube 61 through the airflow inlet 613. In the embodiment illustrated in the present invention, the cross-section of the arc-shaped plate 63 is C-shaped. The central axis O1 of the arc-shaped plate 63 is parallel to the central axis O2 of the swirling tube 61, and the mixing chamber assembly 4 includes an arc-shaped airflow channel 60 located between the arc-shaped plate 63 and the swirling tube 61.

[0027] The mixing chamber housing 5 is provided with a mounting base 531 for mounting a urea nozzle 7, which is used to spray atomized urea droplets into the swirl tube 61. The mixing chamber housing 5 is provided with a first mounting surface 532 near the mounting base 531 and located inside the first cavity 53.

[0028] One end of the arc-shaped plate 63 is provided with a first mounting claw 631 fixed to the first mounting surface 532, and the other end of the arc-shaped plate 63 is provided with a second mounting claw 632 fixed to the partition plate 55. The arc-shaped plate 63 is also provided with a slot 630 located beside the first mounting claw 631, and the slot 630 is connected to the arc-shaped airflow channel 60 to adjust the back pressure. In the embodiment illustrated in the present invention, there are several first mounting claws 631, and the slot 630 is located between two adjacent first mounting claws 631.

[0029] Furthermore, the mixing chamber assembly 4 includes an end assembly 8 located within the second cavity 54 and at the bottom of the connecting pipe 62. The end assembly 8 is generally "boat-shaped." The end assembly 8 includes a bottom wall 81, peripheral walls 82 extending upwards from the periphery of the bottom wall 81, and a buffer cavity 83 formed by the bottom wall 81 and the peripheral walls 82. The peripheral walls 82 have a first side wall 821 facing the second post-treatment carrier assembly 2, a second side wall 822 opposite to the first side wall 821, a first arc-shaped wall 823 located between the first side wall 821 and the second side wall 822, and a second arc-shaped wall 824. The first side wall 821 has several first airflow perforations 825 through which the mixed airflow of exhaust gas and urea droplets flows, thereby facilitating the guidance of the mixed airflow to the downstream end face of the second post-treatment carrier assembly 2. The second side wall 822 has no perforations, thereby preventing the mixed airflow from flowing away from the second post-treatment carrier assembly 2 to form a dead zone. The first arc-shaped wall 823 and the second arc-shaped wall 824 are used to form a swirling flow of the mixed gas flow, thereby increasing the mixing distance and improving the evaporation of urea droplets. Preferably, the bottom wall 81 is inclined, and the end of the bottom wall 81 near the first side wall 821 is lower than the end near the second side wall 822; with this configuration, even if a liquid film is formed, the liquid film will flow out along the inclined bottom wall 81 to one side of the second post-treatment carrier assembly 2, avoiding the formation of urea crystals due to the continuous accumulation of the liquid film. Preferably, the bottom of the first side wall 821 is provided with a guide groove 826 to facilitate the outward flow of liquid; at the same time, the guide groove 826 can also regulate the uniformity of the mixed gas flow when the mixed gas flow out of the buffer chamber 83.

[0030] Furthermore, the mixing chamber assembly 4 may also include an adjusting plate 84 located in the buffer chamber 83. The adjusting plate 84 has several through holes 841, which can further break up the urea droplets. The adjusting plate 84 has a bottom surface 842, wherein the end of the bottom surface 842 near the first sidewall 821 is lower than the end near the second sidewall 822. This arrangement ensures that even if a liquid film forms, the liquid film will flow out along the inclined bottom surface 842 to one side of the second post-treatment carrier assembly 2, avoiding urea crystallization due to continuous accumulation of the liquid film.

[0031] The mixing chamber assembly 4 is further provided with an airflow distribution plate 85, which has a plurality of second airflow perforations 851. The airflow distribution plate 85 and the first sidewall 821 are located on the same side of the buffer chamber 83. With this arrangement, the mixed airflow of exhaust gas and urea droplets can pass through the first airflow perforations 825 and the second airflow perforations 851, thereby facilitating the uniform distribution of the mixed airflow on the end face of the second post-treatment carrier assembly 2.

[0032] The urea crushing tube 64 is located within the first inner cavity 611 and the second inner cavity 621. The urea crushing tube 64 extends along the axial direction M, and its outer wall is provided with a plurality of urea crushing grooves 641. The length L of each urea crushing groove 641 along the axial direction M is greater than its width W along the radial direction N perpendicular to the axial direction M. The urea crushing grooves 641 facilitate further crushing of urea particles into smaller particles, thereby reducing the risk of urea crystallization and improving ammonia uniformity. Furthermore, when urea droplets form a liquid film locally within the urea crushing grooves 641, this liquid film can also move along the axial direction M under the influence of airflow and / or gravity. The moving liquid film is beneficial for absorbing the temperature of the airflow, thus promoting its own evaporation. This design prevents the liquid film from remaining in a certain area for an extended period, thereby greatly reducing the risk of urea crystallization. Even if the liquid film accumulated in the urea breaking tube 64 drips into the end component 8 due to failure to evaporate in time, it can be broken again through the through hole 841 on the adjusting plate 84, which is conducive to the evaporation of urea droplets and reduces the risk of urea crystallization.

[0033] In use, the exhaust gas from the diesel engine passes through the third aftertreatment carrier assembly 3 and the first aftertreatment carrier assembly 1, and enters the first cavity 53 through the first opening 51. Since the arc-shaped plate 63 covers the swirl vane 612 facing the first opening 51, the exhaust gas from the first opening 51 must bypass the arc-shaped plate 63 before entering the swirl tube 61 through the airflow inlet 613. This arrangement avoids a large amount of exhaust gas flowing in from the first opening 51 directly rushing towards the swirl tube 61, thus preventing uneven airflow distribution and improving the resistance to urea crystallization. During this process, most of the exhaust gas enters the swirl tube 61 from both sides through the airflow inlets 613 facing away from the first opening 51 or through the arc-shaped airflow channel 60 from the airflow inlets 613 facing the first opening 51; a small portion of the exhaust gas flows into the swirl tube 61 from the slot 630. The exhaust gas is guided by the swirl plate 612 and rotates into the swirl tube 61. The exhaust gas and urea droplets are mixed in the swirl tube 61 and form a downward rotating airflow. As the airflow flows downward, the urea droplets are further broken up by the urea crushing tube 64. Subsequently, a part of the mixed airflow collides with the urea crushing plate 65, thereby further breaking up the urea droplets. A part of the mixed airflow continues to flow downward until it hits the bottom wall 81 of the end component 8. At this time, a part of the mixed airflow is blocked by the bottom wall 81, rotates and flows upward. The rotating mixed airflow generates a swirling flow along the first arc-shaped wall 823 and the second arc-shaped wall 824, and flows evenly to the end face of the second post-treatment carrier component 2 through the first airflow perforation 825 and the second airflow perforation 851.

[0034] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of this specification should be based on those skilled in the art. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A mixing chamber assembly comprising a mixing chamber housing and a mixing tube assembly mounted within said mixing chamber housing, said mixing chamber housing being provided with a first opening for communicating with a first aftertreatment carrier assembly, a second opening for communicating with a second aftertreatment carrier assembly, a first chamber communicating with said first opening, and a second chamber communicating with said second opening; characterized by: The mixing pipe assembly comprises a swirl pipe in the first cavity and a connecting pipe in the second cavity; the swirl pipe is provided with a first inner cavity, a plurality of swirl vanes and an air inlet corresponding to the swirl vanes, the first inner cavity is communicated with the first cavity through the air inlet, the connecting pipe is provided with a second inner cavity communicated with the first inner cavity, and the second inner cavity is communicated with the second cavity; the mixing pipe assembly further comprises an arc-shaped plate located in the first cavity and partially surrounding the swirl vanes, the arc-shaped plate covers the swirl vanes facing the first opening, so that the exhaust gas needs to bypass the arc-shaped plate to enter the swirl pipe from the air inlet under the blockage of the arc-shaped plate; the central axis of the arc-shaped plate is parallel to the central axis of the swirl pipe, and the mixing cavity assembly comprises an arc-shaped air flow channel between the arc-shaped plate and the swirl pipe.

2. The hybrid chamber assembly of claim 1, wherein: The cross section of the arc-shaped plate is C-shaped.

3. The hybrid chamber assembly of claim 1, wherein: The mixing cavity shell is provided with a mounting seat for mounting a urea nozzle for spraying atomized urea droplets into the swirl pipe.

4. The hybrid chamber assembly of claim 3, wherein: The mixing cavity shell is provided with a first mounting surface close to the mounting seat and located on the inner side of the first cavity, one end of the arc-shaped plate is provided with a first mounting claw fixed on the first mounting surface and a slot located on the side of the first mounting claw, and the slot is communicated with the arc-shaped air flow channel.

5. The hybrid chamber assembly of claim 4, wherein: The mixing cavity shell is provided with a partition plate between the first cavity and the second cavity, and the other end of the arc-shaped plate is provided with a second mounting claw fixed on the partition plate.

6. The hybrid chamber assembly of claim 1, wherein: The mixing cavity assembly comprises an end assembly located in the second cavity and at the bottom of the connecting pipe, the end assembly comprises a bottom wall, a peripheral wall extending upward from the periphery of the bottom wall and a buffer cavity surrounded by the bottom wall and the peripheral wall.

7. The hybrid chamber assembly of claim 6, wherein: The peripheral wall is provided with a first side wall facing the second aftertreatment carrier assembly, and the first side wall is provided with a plurality of first air flow perforations for allowing air flow to pass through.

8. The hybrid chamber assembly of claim 1, wherein: The mixing pipe assembly comprises a urea breaking pipe located in the first inner cavity and the second inner cavity, the urea breaking pipe extends in an axial direction, the urea breaking pipe is provided with a plurality of urea breaking grooves on the outer wall, and the length of the urea breaking grooves along the axial direction is greater than the width of the urea breaking grooves along a radial direction perpendicular to the axial direction.

9. An exhaust gas aftertreatment package comprising a first aftertreatment carrier assembly, a second aftertreatment carrier assembly, a third aftertreatment carrier assembly located upstream of the first aftertreatment carrier assembly, and a mixing chamber assembly connecting the first aftertreatment carrier assembly and the second aftertreatment carrier assembly, wherein the first aftertreatment carrier assembly is a diesel particulate filter, the second aftertreatment carrier assembly is a selective catalytic reduction, and the third aftertreatment carrier assembly is a diesel oxidation catalyst, characterized by: The mixing cavity assembly is the mixing cavity assembly according to any one of claims 1 to 8.

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