End cover integrated mixer and corresponding exhaust system

Abstract

The present invention relates to a mixer, comprising an end cover shell, the end cover shell having an open end, a closed end, and a side wall, the open end being used to connect to an SCR, a first opening and a second opening being independently arranged on the side wall of the end cover shell, the first opening being used to install a nozzle, the second opening being an air inlet of the mixer, a mixing tube and a partition being provided in the inner cavity of the end cover shell, the inner cavity of the end cover shell being divided into a first cavity and a second cavity by the partition, the inlet of the mixing tube being located in the first cavity, the outlet of the mixing tube being located in the second cavity, the portion of the open end of the end cover shell corresponding to the first cavity being closed, the portion of the open end of the end cover shell corresponding to the second cavity being the air outlet of the mixer, the longitudinal axis of the mixing tube being at a preset angle to the longitudinal axis of the end cover shell, and an arc plate being provided below the outlet of the mixing tube. The present invention also relates to a corresponding exhaust system. The system has high integration, low back pressure, good mixing effect, and excellent anti-crystallization performance.

Description

Technical Field

[0001] The present invention relates to the technical field of tail gas treatment, in particular to an end cover integrated mixer and a corresponding exhaust system. Background Art

[0002] With the continuous upgrading of domestic diesel vehicle emission regulations, more stringent requirements are placed on automobile exhaust after-treatment systems and their core components, mixers. As a key component in the after-treatment system, the performance of the mixer directly affects NOx emissions.

[0003] The mixer needs to ensure that the exhaust gas and the reducing agent (such as urea aqueous solution) are fully mixed to improve the conversion efficiency of the SCR system. The mixer also needs to have good heat exchange performance to ensure that the urea aqueous solution is quickly vaporized and fully mixed with the exhaust gas during the injection process, which helps to improve the conversion efficiency of the SCR system and reduce urea consumption. Because the "National VI" standard has stricter emission restrictions under low temperature and low load conditions, and the injection volume increases, the risk of crystallization of the mixer increases. The generation of a large number of crystals will clog the post-treatment channel, resulting in increased back pressure in the post-treatment system and insufficient vehicle power, and there is a risk of emissions exceeding regulatory limits.

[0004] With the upgrade to China VII diesel engine regulations, dual-urea injection systems are a key solution. Compared to China VI exhaust after-treatment systems, these require the addition of urea injection at the inlet of the after-treatment system, a pre-mixer, and an SCR catalyst, posing significant challenges to the after-treatment system's boundaries. The common technical solution involves adding a simple mixer to the pre-exhaust pipe, but this has numerous drawbacks, including poor mixing, high backpressure, and the risk of urea crystallization.

[0005] In general, with the upgrade of regulations, the following problems still exist: the spatial layout of the pre-mixer and after-treatment system for National VII is challenging; the back pressure of the mixer and after-treatment system is high, resulting in poor engine fuel economy; the mixing efficiency of urea crystals and exhaust gas in the mixer is low, and the De-NOx conversion efficiency is low. Summary of the Invention

[0006] In view of the deficiencies of the existing prior art, the present invention provides an end cover integrated mixer and a corresponding exhaust system.

[0007] To achieve the above-mentioned object, the first aspect of the present invention provides an end cover integrated mixer, which has the following technical solutions: the end cover integrated mixer includes an end cover shell, the end cover shell has an open end, a closed end opposite to the open end, and a side wall located between the open end and the closed end, the open end is used to connect to the SCR, the first opening and the second opening are independently arranged on the side wall of the end cover shell, the first opening is used to install the nozzle, the second opening is the air inlet of the mixer, the inner cavity of the end cover shell is provided with a mixing tube and a partition, the mixing tube passes through the partition and is arranged in the inner cavity of the end cover shell, and the mixing tube is passed through the partition to The inner cavity of the end cover shell is divided into a first cavity and a second cavity, the mixing tube has an inlet for air intake and an outlet for air outlet, the inlet of the mixing tube is located in the first cavity, the outlet of the mixing tube is located in the second cavity, the part of the open end of the end cover shell corresponding to the first cavity is closed, and the part of the open end of the end cover shell corresponding to the second cavity is the air outlet of the mixer, so that the exhaust gas enters the first cavity through the air inlet of the mixer and enters the mixing tube through the inlet of the mixing tube, and is mixed with the reducing agent in the mixing tube, and then discharged through the outlet of the mixing tube and the air outlet of the mixer and enters the SCR.

[0008] The longitudinal axis of the mixing tube is at a preset angle with the longitudinal axis of the end cover shell, and the preset angle is 60° to 120°. An arc plate is provided below the outlet of the mixing tube so that the mixed gas flowing out of the outlet of the mixing tube is discharged through the space between the outlet and the arc plate and the gas outlet.

[0009] Preferably, the nozzle is installed in the first opening via a nozzle mounting seat.

[0010] Preferably, the central axes of the first opening and the second opening are perpendicular to the longitudinal axis of the end cover shell.

[0011] Preferably, the portion of the open end corresponding to the first cavity is closed by the partition.

[0012] Preferably, the partition has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube to pass through, the partition has an extension portion extending from the plate body toward the first cavity, and the portion of the open end corresponding to the first cavity is closed by the extension portion.

[0013] Preferably, at least one side of the arc plate has a concave channel, so that the mixed gas flowing out of the outlet of the mixing tube passes through the concave channel and is discharged through the gas outlet.

[0014] Preferably, the arc plate is provided with a plurality of third openings.

[0015] Preferably, the mixing tube includes a swirl tube with swirl blades inside, and several blade windows are set on the upper part of the swirl tube. The several blade windows form the inlet of the mixing tube. When the gas enters the mixing tube through the blade windows, it forms a rotating form. The bottom end opening of the swirl tube is the outlet of the mixing tube.

[0016] A second aspect of the present invention provides an exhaust system, characterized in that it comprises an SCR and the mixer, wherein the mixer is installed on the SCR as an end cover.

[0017] The end cover integrated mixer and the corresponding exhaust system of the present invention utilize the end cone at the inlet of the existing post-processing system to integrate the mixer design, which has high integration, compact space, low back pressure, good mixing effect and excellent anti-crystallization performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments.

[0019] Figure 1 It is a simplified diagram of the principle of the exhaust system of the present invention.

[0020] Figure 2 Schematic diagram of the explosion of the end cover integrated SCR mixer of the present invention.

[0021] Figure 3 This is a schematic diagram illustrating the working principle of the end cover integrated SCR mixer of the present invention.

[0022] Figure 4 It is a partial structural schematic diagram of the end cover integrated SCR mixer of the present invention.

[0023] Reference numerals

[0024] 1 partition; 101 first cavity; 102 second cavity; 2 mixing tube; 3 swirl blade; 4 arc plate; 5 end cover shell; 6 sealing plate; 7 nozzle seat; 8 end cover integrated SCR mixer; 9 SCR; 10 first opening; 11 second opening; 12 open end. DETAILED DESCRIPTION

[0025] In order to more clearly describe the technical content of the present invention, it is further described below in conjunction with specific embodiments.

[0026] like Figure 1The figure shows a schematic diagram of the exhaust system of the present invention. The exhaust system includes an SCR (Sensor-Reducing Reactor) 9 and an end-cap-integrated SCR mixer 8, which is mounted as an end cap on the SCR 9. Exhaust gas enters through the end-cap-integrated SCR mixer 8, mixes with the reductant injected from the nozzle, and undergoes heat exchange. The mixed gas then enters the SCR (Selective Catalytic Reduction) unit (SCR) through the end-cap-integrated SCR mixer 8, where a reduction reaction occurs.

[0027] like Figures 2 to 4 The figure shows a specific embodiment of the end cover integrated SCR mixer 8 of the present invention. The end cover integrated mixer 8 includes an end cover shell 5, which has an open end 12, a closed end opposite to the open end, and a side wall located between the open end and the closed end. The open end 12 is used to connect the SCR 9. The first opening 10 and the second opening 11 are each independently provided on the side wall of the end cover shell 5. The first opening 10 is used to install the nozzle. The second opening 11 is the air inlet of the mixer. The engine exhaust enters the mixer through the air inlet to be mixed with the reductant. The inner cavity of the end cover shell 5 is provided with a mixing tube 2 and a partition 1. The mixing tube 2 passes through the partition 1 and is provided in the inner cavity of the end cover shell 5. Figure 3 As shown, the inner cavity of the end cover shell 5 is divided into a first cavity 101 and a second cavity 102 by the partition 1, and the mixing tube 2 has an inlet for air intake and an outlet for air outlet. The inlet of the mixing tube 2 is located in the first cavity 101, and the outlet of the mixing tube 2 is located in the second cavity 102. The part of the open end 12 of the end cover shell 5 corresponding to the first cavity 101 is closed, and the part of the open end 12 of the end cover shell 5 corresponding to the second cavity 102 is the air outlet of the mixer, and the mixed gas is discharged from the air outlet, so that the exhaust gas enters the first cavity 101 through the air inlet of the mixer and enters the mixing tube 2 through the inlet of the mixing tube 2. After being mixed with the reducing agent in the mixing tube 2, the exhaust gas is discharged through the outlet of the mixing tube 2 and the air outlet of the mixer and enters the SCR.

[0028] The end-cap integrated SCR mixer provided by the present invention integrates the end cap for encapsulating post-processing with the mixer components, and creatively integrates the air inlet and nozzle of the mixer independently on the side wall of the end-cap shell. After entering the inner cavity, the exhaust gas is mixed with the reducing agent in the mixing tube, and the open end of the end-cap shell can be directly connected to the SCR. The present invention pioneers a highly integrated and compact mixer structure with low back pressure and good mixing effect.

[0029] The nozzle is installed in the first opening 10 via the nozzle mounting seat 7. The first opening 10 is provided with a sealing plate 6 to mount the nozzle mounting seat 7, and the mixing tube 2 passes through the opening of the sealing plate 6 to enable the nozzle to spray the reducing agent into the mixing tube 2.

[0030] like Figures 2 to 3 As shown, the end cap housing 5 has a longitudinal axis that passes through the open end 12 and the closed end. The longitudinal axis of the mixing tube 2 is perpendicular to the longitudinal axis of the end cap housing 5. The central axes of the first opening 10 and the second opening 11 are both perpendicular to the longitudinal axis of the end cap housing 5. The first opening 10 and the second opening 11 are both disposed on the sidewall of the end cap housing 5. The mixing tube 2 can also be disposed in a non-perpendicular position within the inner cavity of the end cap housing, for example, tilted at an angle between 60° and 120°.

[0031] like Figure 3 and Figure 4 As shown, the portion of the open end 12 corresponding to the first cavity 101 is closed by the partition 1.

[0032] Specifically, the partition 1 has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube 2 to pass through, and the partition 1 has an extension portion extending from the plate body toward the first cavity 101, and the portion of the open end 12 corresponding to the first cavity 101 is closed by the extension portion.

[0033] like Figures 2 to 4 As shown, an arc plate 4 is provided below the outlet of the mixing tube 2. Both sides of the arc plate 4 have concave channels, so that the mixed gas flowing out of the outlet of the mixing tube 2 is discharged through the concave channels and the outlet. The arc plate 4 used in this embodiment is generally bowl-shaped.

[0034] In this embodiment, the arc plate 4 is provided with a plurality of third openings. High-temperature gas can enter the bottom of the arc plate through the third openings, removing any urea liquid film and urea crystals that may have accumulated in the space between the bottom of the arc plate and the arc wall of the end cap housing 5. This effectively improves crystallization performance, facilitates urea evaporation, and enhances ammonia mixing efficiency.

[0035] like Figures 2 to 4As shown, the mixing tube 2 includes a swirl tube with swirl blades 3 installed inside. Several blade windows are provided at the top of the swirl tube 2, forming the inlet of the mixing tube 2. Gas forms a swirling shape when entering the mixing tube 2 through the blade windows. The bottom opening of the swirl tube 2 serves as the outlet of the mixing tube 2. The blade windows and swirl blades of the swirl tube enable efficient swirl to be formed inside the end cap-integrated SCR mixer of the present invention, resulting in excellent performance. The sidewalls of the swirl tube can be perforated, and the blades in the blade windows can face either inward or outward.

[0036] The end cap integrated SCR mixer and the corresponding exhaust system of the present invention utilize the end cone at the inlet of the existing after-treatment system to integrate the mixer design, which has high integration, compact space, low back pressure, good mixing effect and excellent anti-crystallization performance.

[0037] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

Claims

1. An end cover integrated mixer, characterized in that: The invention comprises an end cover shell, wherein the end cover shell has an open end, a closed end opposite to the open end, and a side wall between the open end and the closed end, wherein the open end is used to connect to the SCR, a first opening and a second opening are independently arranged on the side wall of the end cover shell, wherein the first opening is used to install the nozzle, and the second opening is the air inlet of the mixer, and the inner cavity of the end cover shell is provided with a mixing tube and a partition, wherein the mixing tube passes through the partition and is arranged in the inner cavity of the end cover shell, and the inner cavity of the end cover shell is divided into a first cavity and a second cavity by the partition, and the mixer The mixing tube has an inlet for air intake and an outlet for air outlet. The inlet of the mixing tube is located in the first cavity, and the outlet of the mixing tube is located in the second cavity. The portion of the open end of the end cover shell corresponding to the first cavity is closed, and the portion of the open end of the end cover shell corresponding to the second cavity is the air outlet of the mixer, so that the exhaust gas enters the first cavity through the air inlet of the mixer and enters the mixing tube through the inlet of the mixing tube. After being mixed with the reducing agent in the mixing tube, the exhaust gas is discharged through the outlet of the mixing tube and the air outlet of the mixer and enters the SCR; The longitudinal axis of the mixing tube forms a preset angle with the longitudinal axis of the end cover housing, and the preset angle is 60° to 120°. An arc plate is provided below the outlet of the mixing tube so that the mixed gas flowing out of the outlet of the mixing tube passes through the space between the outlet and the arc plate and is discharged through the gas outlet. The portion of the open end corresponding to the first cavity is closed by the partition; The partition plate has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube to pass through, the partition plate has an extension portion extending from the plate body toward the first cavity, and the extension portion closes the portion of the open end corresponding to the first cavity; At least one side of the arc plate has a concave channel, and the mixed gas flowing out of the outlet of the mixing pipe passes through the concave channel and is discharged through the gas outlet; The arc plate is provided with a plurality of third openings.

2. The end cover integrated mixer according to claim 1, characterized in that: The nozzle is installed in the first opening via a nozzle mounting seat.

3. The end cover integrated mixer according to claim 1, characterized in that: The central axes of the first opening and the second opening are both perpendicular to the longitudinal axis of the end cover shell.

4. The end cover integrated mixer according to claim 1, characterized in that: The mixing tube includes a swirl tube with swirl blades inside. Several blade windows are set on the upper part of the swirl tube. The several blade windows form the inlet of the mixing tube. When the gas enters the mixing tube through the blade windows, it forms a rotating form. The bottom end opening of the swirl tube is the outlet of the mixing tube.

5. An exhaust system, characterized in that: The invention comprises an SCR and the mixer according to any one of claims 1 to 4, wherein the mixer is installed on the SCR as an end cover.

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