A diesel engine aftertreatment urea mixer structure that inhibits pn increase
The urea mixer, designed with a swirl structure and perforated plate, solves the problems of increased nitrogen oxides (PN) and urea crystallization caused by metal mesh, achieving dual optimization of PN and nitrogen oxides, meeting stringent emission regulations and reducing engine wear.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHENGZHOU JINGYIDA AUTO PARTS
- Filing Date
- 2025-10-10
- Publication Date
- 2026-08-04
AI Technical Summary
In existing diesel engine aftertreatment systems, the metal mesh structure leads to an increase in the number of particulate matter (PN) concentration in the exhaust gas, posing a risk of exceeding regulatory limits, and the problem of urea crystal formation has not been effectively solved.
The urea mixer, which adopts a swirl structure and a perforated plate structure, includes an upper swirl tube, a lower swirl tube, a broken mesh plate, an outlet mixing blade plate, and an outlet baffle plate. Through multi-stage synergistic mixing, it improves the mixing uniformity of exhaust gas and urea, reduces particulate matter generation and urea crystallization, and works in conjunction with the SCR system for catalytic reduction reaction.
It effectively controls PN emissions, improves nitrogen oxide conversion rate, meets the requirements of China VI and above emission regulations, while reducing exhaust pressure loss, avoiding engine power loss, and balancing emission control and power economy.
Smart Images
Figure CN224592209U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of aftertreatment systems, specifically relating to a diesel engine aftertreatment urea mixer structure that suppresses PN increase. Background Technology
[0002] Currently, mainstream diesel engine aftertreatment systems generally adopt a technical route of DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + MIXer (Mixer) + SCR (Selective Catalytic Reduction) + ASC (Ammonia Slip Catalyst). The core function of the mixer is to achieve thorough mixing of exhaust gas and urea, improve the uniformity of exhaust gas flow distribution, and simultaneously prevent urea crystallization. Through this mixing effect, it further works in conjunction with the SCR unit to catalytically convert exhaust pollutants to meet the corresponding emission standards.
[0003] With the upgrading of diesel engine emission regulations to the China VI standard or the off-road T4 stage, pollutant emission limits have become more stringent, leading to a corresponding increase in urea injection volume. This places higher demands on the anti-urea crystallization performance of the mixer structure. Against this backdrop, most existing mainstream mixer structures adopt a metal wire mesh (steel wire mesh) structure to solve the urea crystallization problem.
[0004] However, with the improvement of the accuracy of exhaust pollutant measurement equipment and the further optimization of emission regulations, comparative experimental studies have found that the metal wire mesh (steel wire mesh) structure has an excessive ability to break up particles in the exhaust gas, which can easily lead to an increase in the PN (particulate matter number) concentration in exhaust pollutants, posing a risk that PN emissions may exceed the regulatory limits. Summary of the Invention
[0005] To address the aforementioned issues, this invention proposes a diesel engine aftertreatment urea mixer structure that suppresses PN (particulate matter) increase. Through a swirl structure and a perforated plate structure, the urea crystallization problem is solved without causing PN increase, while also meeting requirements for exhaust gas flow uniformity, pollutant conversion efficiency, and pollutant emissions.
[0006] The technical solution adopted in this utility model is as follows: a diesel engine aftertreatment urea mixer structure for suppressing PN increase, including a heat insulation cover, a mixer cylinder, an upper swirl tube, a mixing chamber, a lower swirl tube, a crushing mesh plate, a nozzle base, an outlet mixing blade plate, and an outlet baffle plate; the heat insulation cover is provided on the outer side of the mixer cylinder; the mixing chamber is provided inside the mixer cylinder, the upper end of the mixing chamber is connected to the upper swirl tube, and the lower end is connected to the lower swirl tube; the crushing mesh plate is provided inside the mixing chamber; the crushing mesh plate is located at the connection between the mixing chamber and the lower swirl tube; the nozzle base is provided on the mixer cylinder, the nozzle base is located above the upper swirl tube, and is used to install the urea nozzle; the outlet end of the mixer cylinder is sequentially provided with the outlet mixing blade plate and the outlet baffle plate.
[0007] Furthermore, the mixing chamber is a pocket-shaped structure with its opening facing the air outlet, and a number of purge holes are opened on its air inlet end face. A blocking plate is provided on the outer side of the air outlet end face of the mixing chamber.
[0008] Furthermore, the diameter of the blocking plate is the same as the inner diameter of the mixer cylinder.
[0009] Furthermore, the outlet mixing blade plate has a plurality of outlet mixing blades, which are evenly distributed along the circumference of the mixer cylinder and form an angle of 0-60° with the radial direction of the outlet mixing blade plate.
[0010] Furthermore, the exhaust spoiler is a ring structure, and its ring structure covers the exhaust mixing blades of the exhaust mixing blade plate.
[0011] Furthermore, the upper and lower swirl tubes are provided with grid-like flow holes or strip-shaped flow holes in the circumferential direction; the strip-shaped flow holes are at an angle of 45° or 135° to the horizontal.
[0012] Furthermore, the broken mesh plate is made of metal and has multiple through holes evenly distributed on it.
[0013] Furthermore, the air inlet end of the mixer cylinder has a flared structure.
[0014] The beneficial effects of this utility model are:
[0015] 1. This utility model, through a multi-stage synergistic mixing structure consisting of an upper swirling tube, a lower swirling tube, a broken mesh plate, an exhaust mixing blade plate, and an exhaust baffle plate, can significantly improve the mixing uniformity of urea and diesel engine exhaust, reduce particulate matter generation and urea crystallization caused by uneven mixing, help the SCR system to efficiently complete the catalytic reduction reaction, thereby effectively controlling PN emissions and meeting the requirements of China VI and above emission regulations.
[0016] 2. While enhancing the PN control effect, this structure can improve the nitrogen oxide conversion rate and achieve dual optimization of PN and nitrogen oxide emissions; moreover, the grid hole structure of the upper / lower swirl tube and the flow design of the broken mesh plate are matched with each other, which can reduce exhaust pressure loss while ensuring the mixing effect, avoid engine power loss, and balance emission control and power economy.
[0017] 3. The crushing mesh plate inside the mixing chamber can block large urea particles, and the swirling airflow reduces the risk of urea crystallization; the heat insulation cover on the outside of the mixer cylinder can prevent urea from vaporizing prematurely and protect external components from high temperature; in addition, all functional components are integrated into the cylinder, which is compact and flexible in installation. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of this utility model;
[0019] Figure 2 This is a schematic diagram of the connection structure of the upper vortex tube, the mixing cavity, and the lower vortex tube in this utility model;
[0020] Figure 3 This is an exploded view of the structure of this utility model;
[0021] Figure 4 This is a schematic diagram of the structure of the exhaust mixing blade plate in this utility model;
[0022] Figure 5 This is a schematic diagram of other structures of the exhaust mixing blade plate in this utility model;
[0023] Figure 6 This is a schematic diagram of other forms of the upper vortex tube, mixing cavity, and lower vortex tube in this utility model;
[0024] In the figure: 1-heat insulation cover, 2-mixer cylinder, 3-upper swirl tube, 4-mixing chamber, 5-lower swirl tube, 6-crushing mesh plate, 7-nozzle base, 8-exhaust mixing blade plate, 9-exhaust baffle plate, 10-purge hole, 11-blocking plate, 12-exhaust mixing blade. Detailed Implementation
[0025] To more clearly illustrate the technical solution of this utility model, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort. To facilitate understanding of this utility model, a more detailed description of this utility model will be provided below in conjunction with the accompanying drawings and specific embodiments.
[0026] like Figures 1-3As shown, this utility model is a diesel engine aftertreatment urea mixer structure for suppressing PN increase, including a heat shield 1, a mixer body 2, an upper swirl tube 3, a mixing chamber 4, a lower swirl tube 5, a perforated plate 6, a nozzle base 7, an outlet mixing blade plate 8, and an outlet baffle plate 9. The exhaust gas inlet end of the mixer body 2 has a flared connection structure for connecting to the DPF catalytic converter unit structure of the aftertreatment. The outer side of the mixer body 2 is covered by the heat shield 1, and the inner side is provided with the mixing chamber 4. The mixing chamber 4 is a pocket-shaped structure with its opening facing the outlet end, and several purge holes 10 are opened laterally on its inlet end face. The upper end of the mixing chamber 4 is connected to the lower end of the upper swirl tube 3, and the lower end of the mixing chamber 4 is connected to the upper end of the lower swirl tube 5. The upper end of the upper swirl tube 3 and the lower end of the lower swirl tube 5 are welded and fixed to the mixer body 2. Both the upper swirl tube 3 and the lower swirl tube 5 are provided with grid-like flow holes in the circumferential direction. A metal perforated plate 6 is installed at the connection between the mixing chamber 4 and the lower swirl tube 5. A blocking plate 11 is provided on the outer side of the outlet end face of the mixing chamber 4. The diameter of the blocking plate 11 is the same as the inner diameter of the mixer cylinder 2. These components constitute the main structure of the mixer. A nozzle base 7 is provided on the mixer cylinder 2. The nozzle base 7 is located above the upper swirl tube 3 and is used to install the urea nozzle. An outlet mixing blade plate 8 and an outlet baffle plate 9 are sequentially provided at the outlet end of the mixer cylinder 2. Their diameters are the same as the inner diameter of the mixer cylinder 2 and they are welded to the inner side of the mixer cylinder 2.
[0027] like Figure 4 As shown, a number of air mixing blades 12 are opened on the air mixing blade plate 8. The air mixing blades 12 are evenly distributed along the circumference of the mixer cylinder 2 and form a 45° angle with the radial direction of the air mixing blade plate 8.
[0028] like Figure 3 As shown, the exhaust spoiler 9 has a ring structure, and its ring structure covers the exhaust mixing blades 12 of the exhaust mixing blade plate 8.
[0029] like Figure 5 The diagram shows two other structures of the exhaust mixing blade plate 8 of this utility model. In this structure, more exhaust mixing blades 12 are arranged, and the radial angle between them and the exhaust mixing blade plate 8 is smaller.
[0030] like Figure 6 The above describes another structure of the upper swirling tube, mixing cavity, and lower swirling tube of this utility model. In this structure, the upper swirling tube 3 and the lower swirling tube 5 are provided with strip-shaped flow holes in the circumferential direction; the strip-shaped flow holes form an angle of 45° or 135° with the horizontal.
[0031] The principle of this invention is as follows: When the exhaust gas passes through the exhaust gas inlet of the trumpet-shaped mixer cylinder 2, it enters the mixing chamber 4 through the upper / lower swirl tubes 3 and 5. Urea mixes with the exhaust gas after passing through the upper swirl tube 3 and the mixing chamber 4, and finally contacts the crushing mesh plate. This invention makes the mixture of exhaust gas and urea more uniform through the upper / lower swirl tubes 3 and 5. The urea impacts the crushing mesh plate, which can have a crushing effect, and the exhaust gas passing through the lower swirl tube 5 and the purging hole 10 can purge the urea, greatly reducing the risk of urea crystallization. Finally, the mixed airflow flows out of the mixing chamber 4, passes through the outlet mixing blade plate 8 and the outlet baffle plate 9 for equalization, and enters the SCR catalytic unit. The openings of the outlet mixing blade plate 8 are on the outside, and the openings of the outlet baffle plate 9 are in the center. This opening method makes the airflow mixing more uniform and also makes the airflow distribution more uniform as it enters the SCR unit.
[0032] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A diesel after treatment urea mixer structure to inhibit PN increase, characterized by, It includes a heat shield (1), a mixer cylinder (2), an upper swirl tube (3), a mixing chamber (4), a lower swirl tube (5), a breaking mesh plate (6), a nozzle base (7), an outlet mixing blade plate (8), and an outlet baffle plate (9). The heat insulation cover (1) is provided on the outer side of the mixer cylinder (2); The mixing chamber (4) is provided inside the mixer cylinder (2). The upper end of the mixing chamber (4) is connected to the upper swirl tube (3), and the lower end is connected to the lower swirl tube (5). The mixing chamber (4) is provided with the crushing mesh plate (6); the crushing mesh plate (6) is located at the connection between the mixing chamber (4) and the lower vortex tube (5); The nozzle base (7) is provided on the mixer cylinder (2), and the nozzle base (7) is located above the upper swirl tube (3) for installing urea nozzles; The outlet end of the mixer cylinder (2) is provided with the outlet mixing blade plate (8) and the outlet baffle plate (9) in sequence.
2. A diesel after-treatment urea mixer structure to suppress PN increase according to claim 1, characterized in that, The mixing chamber (4) is a pocket-shaped structure with its opening facing the air outlet. Several purge holes (10) are opened on its air inlet end face. A blocking plate (11) is provided on the outer side of the air outlet end face of the mixing chamber (4).
3. A diesel after-treatment urea mixer structure to suppress PN increase according to claim 2, characterized in that, The diameter of the blocking plate (11) is the same as the inner diameter of the mixer cylinder (2).
4. The diesel after-treatment urea mixer structure to suppress the PN increase according to claim 1, characterized in that, The outlet mixing blade plate (8) has a plurality of outlet mixing blades (12), which are evenly distributed along the circumference of the mixer cylinder (2) and form an angle of 0-60° with the radial direction of the outlet mixing blade plate (8).
5. The diesel after-treatment urea mixer structure to suppress the PN increase according to claim 1, characterized in that, The exhaust spoiler (9) has a ring structure, and its ring structure covers the exhaust mixing blade (12) of the exhaust mixing blade plate (8).
6. A diesel after-treatment urea mixer structure to suppress PN increase according to claim 1, characterized in that, The upper swirl tube (3) and the lower swirl tube (5) are provided with grid-like flow holes or strip-shaped flow holes in the circumferential direction; the strip-shaped flow holes are at an angle of 45° or 135° to the horizontal.
7. The diesel after-treatment urea mixer structure to suppress the PN increase according to claim 1, characterized in that, The broken mesh plate (6) is made of metal and has multiple through holes evenly distributed on it.
8. The diesel after-treatment urea mixer structure to suppress the PN increase according to claim 1, wherein The air inlet of the mixer cylinder (2) is a flared structure.