Engine exhaust treatment system and vehicles equipped with it

Abstract

This invention provides an engine exhaust gas treatment system and a vehicle having the same. The engine exhaust gas treatment system includes: a first treatment unit having an exhaust gas inlet, a high-flow-rate outlet, and a low-flow-rate outlet; and a second treatment unit having a high-flow-rate inlet, a low-flow-rate inlet, and an exhaust gas outlet. The high-flow-rate outlet is connected to the high-flow-rate inlet to form a high-flow-rate exhaust pipe, and the low-flow-rate outlet is connected to the low-flow-rate inlet to form a low-flow-rate exhaust pipe. The low-flow-rate inlet is located between the high-flow-rate inlet and the exhaust gas outlet. Exhaust gas flowing into the second treatment unit from the low-flow-rate exhaust pipe is treated by the treatment unit located between the low-flow-rate inlet and the exhaust gas outlet before being discharged from the second treatment unit. This application solves the problem of low catalyst utilization caused by uneven airflow distribution in traditional SCR aftertreatment systems in the prior art.

Description

Technical Field

[0001] This invention relates to the field of engine exhaust aftertreatment technology, and more specifically, to an engine exhaust gas treatment system and a vehicle having the same. Background Technology

[0002] In existing technologies, conventional diesel vehicle aftertreatment systems (such as DOC+DPF+SCR) suffer from problems such as low SCR catalyst volume utilization, high exhaust back pressure, high aftertreatment noise, and difficulty in low-temperature ignition under low-flow engine conditions (such as idling and low load). Because SCRs typically employ a full-size arrangement and uniformly use high-temperature resistant zeolite catalysts, exhaust gas only flows through the front end of the SCR at low flow rates, leaving a large amount of catalytic space unused. Furthermore, to maintain catalytic efficiency, additional heating or the use of high-cost full zeolite catalysts is required, resulting in high costs, significant heat loss, and low system response efficiency. However, under high-flow conditions, while the full SCR channel can effectively treat high concentrations of NO... x However, due to the continuous exposure to high-temperature exhaust in the front section, the aging of the high-temperature resistant catalyst is accelerated, shortening the overall service life.

[0003] There is currently no effective solution to the aforementioned technical problems. Summary of the Invention

[0004] The main objective of this invention is to provide an engine exhaust gas treatment system and a vehicle having the same, in order to solve the problem of low catalyst utilization caused by uneven airflow distribution in traditional SCR aftertreatment systems in the prior art.

[0005] To achieve the above objectives, according to one aspect of the present invention, an engine exhaust gas treatment system is provided, comprising: a first treatment unit having an exhaust gas inlet, a high-flow-rate outlet, and a low-flow-rate outlet; and a second treatment unit having a high-flow-rate inlet, a low-flow-rate inlet, and an exhaust gas outlet, wherein the high-flow-rate outlet is connected to the high-flow-rate inlet to form a high-flow-rate exhaust pipe, and the low-flow-rate outlet is connected to the low-flow-rate inlet to form a low-flow-rate exhaust pipe; wherein the low-flow-rate inlet is located between the high-flow-rate inlet and the exhaust gas outlet, and exhaust gas flowing into the second treatment unit from the low-flow-rate exhaust pipe is treated by the treatment unit located between the low-flow-rate inlet and the exhaust gas outlet and then discharged from the second treatment unit.

[0006] Furthermore, the second processing unit includes a tank body, a high-flow inlet and an exhaust outlet respectively located at two opposite ends of the tank body, and a low-flow inlet located between the high-flow inlet and the exhaust outlet. The exhaust gas entering the tank body from the high-flow exhaust pipe is processed by the processing unit located between the high-flow inlet and the low-flow inlet, and then processed by the processing unit located between the low-flow inlet and the exhaust outlet before being discharged from the second processing unit.

[0007] Furthermore, the tank body contains a variety of catalyst carriers, which are arranged along the direction of exhaust gas flow.

[0008] Furthermore, the catalyst supports include at least two of the following: SCR iron-based catalyst supports, SCR copper-based catalyst supports, and SCR zeolite-type catalyst supports. The SCR iron-based catalyst supports and SCR copper-based catalyst supports are located in the tank between the low-flow-rate inlet and the exhaust gas outlet, while the SCR zeolite-type catalyst supports are located in the tank between the high-flow-rate inlet and the low-flow-rate inlet.

[0009] Furthermore, it also includes: an ASC treatment unit, the inlet of which is connected to the exhaust gas outlet, and the outlet of which is connected to the atmospheric environment.

[0010] Furthermore, at least one of a flow sensor, a nitrogen oxide sensor, a temperature sensor, and a differential pressure sensor is installed at the exhaust gas inlet, and / or an NH3 sensor and a NO sensor are installed at the outlet of the ASC treatment unit. x At least one of the sensors.

[0011] Furthermore, the engine exhaust treatment system also includes: a urea tank; a urea pump, the inlet of which is connected to the urea tank, and the outlet of which is equipped with a main channel urea nozzle and a bypass channel urea nozzle. The main channel urea nozzle is connected to a high-flow exhaust pipe, and the bypass channel urea nozzle is connected to a low-flow exhaust pipe.

[0012] Furthermore, a main channel mixer is installed in the pipeline between the main channel urea nozzle and the high-flow inlet, and a bypass channel mixer is installed in the pipeline between the bypass channel urea nozzle and the low-flow inlet, and / or, valve structures are installed in both the high-flow exhaust pipeline and the low-flow exhaust pipeline.

[0013] Furthermore, the first processing unit includes an oxidation catalyst unit and a particulate trap unit.

[0014] According to another aspect of the present invention, a vehicle is provided having an engine exhaust gas treatment system, which is the engine exhaust gas treatment system described above.

[0015] By applying the technical solution of this invention, intelligent zoning and adaptive flow control of the catalytic zone are achieved through a dual-channel diversion structure and an asymmetric inlet layout. The engine exhaust gas treatment system includes a first treatment unit and a second treatment unit. The first treatment unit has an exhaust gas inlet, a high-flow-rate outlet, and a low-flow-rate outlet to complete the oxidation and particulate matter capture of the exhaust gas. The second treatment unit has a high-flow-rate inlet, a low-flow-rate inlet, and an exhaust gas outlet, wherein the low-flow-rate inlet is located between the high-flow-rate inlet and the exhaust gas outlet, forming the downstream catalytic inlet. The high-flow-rate outlet and the high-flow-rate inlet are connected to form a high-flow-rate exhaust pipe, and the low-flow-rate outlet and the low-flow-rate inlet are connected to form a low-flow-rate exhaust pipe. Under low-flow engine operating conditions, the system closes the high-flow exhaust pipe and opens the low-flow exhaust pipe. Exhaust gas flows through the low-flow exhaust pipe only through the low-temperature, high-efficiency catalyst zone between the low-flow inlet and outlet, avoiding passage through the high-temperature resistant catalyst in the front section. This significantly improves catalyst utilization, reduces exhaust back pressure and aerodynamic noise, and reduces the amount of expensive catalyst used. Under high-flow operating conditions, the low-flow exhaust pipe closes, and exhaust gas flows through the high-flow exhaust pipe, ensuring high-efficiency conversion. This structure utilizes exhaust waste heat for low-temperature ignition without external heating, adapting to frequent idling and low-load operation scenarios, and combining cost advantages with durability. The system achieves precise flow response and closed-loop emission management, overcoming the technical bottlenecks of traditional SCR systems such as ineffective cavity, high back pressure, high noise, and catalyst waste under low flow conditions. This application solves the problem of low catalyst utilization caused by uneven airflow distribution in existing traditional SCR aftertreatment systems. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of an embodiment of the engine exhaust gas treatment system according to the present invention is shown.

[0017] The above figures include the following reference numerals: 1. First processing unit; 11. Exhaust gas inlet; 12. High-flow outlet; 13. Low-flow outlet; 2. Second processing unit; 20. Tank body; 200. High-flow exhaust pipe; 201. High-flow inlet; 202. Low-flow inlet; 203. Exhaust gas outlet; 23. Main channel urea nozzle; 24. Urea pump; 25. Urea tank; 26. Main channel mixer; 27. Bypass channel urea nozzle; 28. Bypass channel mixer; 3. ASCII processing unit; 4. ECU; 41. Flow sensor; 42. Nitrogen oxide sensor; 43. Temperature sensor; 44. Differential pressure sensor; 45. NH3 sensor; 46. NO x sensor; 52. Main channel valve; 55. Bypass channel valve; 56. Low flow exhaust pipeline. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to denote the same devices, and therefore their description will be omitted.

[0022] Combination Figure 1 As shown, according to a specific embodiment of this application, an engine exhaust gas treatment system is provided.

[0023] To achieve the above objectives, according to one aspect of the present invention, an engine exhaust gas treatment system is provided, comprising: a first treatment unit 1 having an exhaust gas inlet 11, a high-flow outlet 12, and a low-flow outlet 13; a second treatment unit 2 having a high-flow inlet 201, a low-flow inlet 202, and an exhaust gas outlet 203, wherein the high-flow outlet 12 is connected to the high-flow inlet 201 to form a high-flow exhaust pipe 200, and the low-flow outlet 13 is connected to the low-flow inlet 202 to form a low-flow exhaust pipe 56; wherein the low-flow inlet 202 is located between the high-flow inlet 201 and the exhaust gas outlet 203, and the exhaust gas flowing into the second treatment unit 2 through the low-flow exhaust pipe 56 is treated by the treatment unit located between the low-flow inlet 202 and the exhaust gas outlet 203 and then discharged from the second treatment unit 2.

[0024] By applying the technical solution of this invention, intelligent zoning and adaptive flow control of the catalytic converter area are achieved through a dual-channel diversion structure and an asymmetric inlet layout. The engine exhaust gas treatment system includes a first treatment unit 1 and a second treatment unit 2. The first treatment unit 1 has an exhaust gas inlet 11, a high-flow outlet 12, and a low-flow outlet 13 to complete the oxidation and particulate matter capture of the exhaust gas. The second treatment unit 2 has a high-flow inlet 201, a low-flow inlet 202, and an exhaust gas outlet 203, wherein the low-flow inlet 202 is located between the high-flow inlet 201 and the exhaust gas outlet 203, forming the downstream catalytic converter inlet. The high-flow outlet 12 is connected to the high-flow inlet 201 to form a high-flow exhaust pipe 200, and the low-flow outlet 13 is connected to the low-flow inlet 202 to form a low-flow exhaust pipe 56. Under low-flow engine operating conditions, the system closes the high-flow exhaust pipe 200 and opens the low-flow exhaust pipe 56. Exhaust gas flows through the low-flow exhaust pipe 56 only through the low-temperature, high-efficiency catalyst zone between the low-flow inlet 202 and the exhaust outlet 203, avoiding passage through the high-temperature resistant catalyst in the front section. This significantly improves catalyst utilization efficiency, reduces exhaust back pressure and aerodynamic noise, and reduces the amount of expensive catalyst used. Under high-flow operating conditions, the low-flow exhaust pipe 56 is closed, and exhaust gas flows through the high-flow exhaust pipe 200, ensuring high-efficiency conversion. This structure can utilize exhaust waste heat for low-temperature ignition without external heating, adapting to frequent idling and low-load operation scenarios, and combining cost advantages with durability. The system achieves precise flow response and closed-loop emission management, overcoming the technical bottlenecks of traditional SCR systems such as ineffective cavity, high back pressure, high noise, and catalyst waste under low flow conditions. This application solves the problem of low catalyst utilization caused by uneven airflow distribution in existing traditional SCR aftertreatment systems.

[0025] Furthermore, the first processing unit 1 includes an oxidation catalyst unit and a particulate trap unit.

[0026] DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particulate Filter) are two core pre-treatment units in modern engine aftertreatment systems. Together, they are responsible for purifying unburned hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM) in the exhaust gas, laying the foundation for the efficient operation of the subsequent SCR system.

[0027] A Direct Catalytic Converter (DOC) is a catalytic device that uses precious metals (such as platinum (Pt) and palladium (Pd) as the active component. It typically employs a honeycomb ceramic or metal support structure, coated with a high specific surface area catalytic coating. Its main function is to convert harmful components in exhaust gas into harmless substances through oxidation reactions: carbon monoxide (CO) is oxidized to carbon dioxide (CO2), unburned hydrocarbons (HC) are oxidized to water (H2O) and carbon dioxide, and simultaneously, nitric oxide (NO) in the exhaust gas is partially oxidized to nitrogen dioxide (NO2) in the DOC. This NO→NO2 conversion is crucial because NO2 has higher reactivity in subsequent passive regeneration of the DPF and the SCR reaction, significantly improving the oxidation efficiency of particulate matter and NO. x Reduction rate. In addition, DOC can increase exhaust temperature during operation, which helps improve the ignition performance of downstream SCR catalysts, especially playing a key role under cold start or low load conditions.

[0028] A Diesel Particulate Filter (DPF) is a physical filter used to capture micron-sized particulate matter (PM) in diesel exhaust. It is typically made of porous ceramic materials (such as silicon carbide or cordierite) with a honeycomb structure. Adjacent channels are closed at one end and open at the other, forming a "wall-flow" structure. As exhaust gas flows through the DPF, particulate matter is intercepted on the channel walls, achieving a PM capture efficiency of over 95%. However, with increased operating time, the captured particulate matter gradually accumulates, leading to increased exhaust back pressure and affecting engine performance. Therefore, the DPF needs to be periodically "regenerated"—that is, the accumulated soot is oxidized into CO2 through high-temperature combustion. Regeneration is divided into two types: active regeneration and passive regeneration. Passive regeneration relies on NO2 generated from DOC to oxidize the soot at a relatively low temperature (approximately 250–400°C), suitable for long-term medium-to-high load operation. Active regeneration, on the other hand, uses the ECU to control additional fuel injection, electric heating, or post-injection of fuel to raise the exhaust temperature to over 550°C, forcibly igniting the soot, suitable for frequent idling or urban driving conditions. The DPF's differential pressure sensor monitors the pressure difference before and after filtration in real time, providing a regeneration trigger signal to the ECU and ensuring long-term stable operation of the system.

[0029] In this invention, the first processing unit 1 integrates a DOC and a DPF. During the exhaust gas flow, the DOC completes the oxidation and conversion of hydrocarbons (HC) and carbon monoxide (CO), and oxidizes some nitric oxide (NO) to nitrogen dioxide (NO2) to promote the subsequent SCR reaction. The DPF efficiently captures particulate matter (PM) in the exhaust gas, and when the differential pressure sensor detects that the back pressure exceeds the limit, it achieves regeneration and cleaning through active or passive regeneration. As the first processing unit 1, the DOC and DPF jointly complete the preliminary purification of the exhaust gas, which not only effectively reduces PM emissions, but also optimizes the reaction environment of the subsequent SCR by generating NO2. At the same time, it provides a stable and clean upstream airflow for the bypass structure, ensuring that the SCR catalyst can obtain stable and controllable reaction conditions under different flow conditions. It is an indispensable basic link for achieving efficient, low-noise, and low-back-pressure operation of the overall after-treatment system.

[0030] It needs to be further explained that, such as Figure 1 As shown in the schematic diagram of the engine exhaust gas treatment system of the present invention, it does not mean that the various units must be arranged in a straight line, and they can also be arranged in a U-shape, S-shape, etc.

[0031] Furthermore, the second processing unit 2 includes a tank body 20, a high-flow inlet 201 and an exhaust outlet 203 respectively disposed on two opposite ends of the tank body 20, and a low-flow inlet 202 located between the high-flow inlet 201 and the exhaust outlet 203. The exhaust gas entering the tank body 20 from the high-flow exhaust pipe 200 is processed by the processing unit located between the high-flow inlet 201 and the low-flow inlet 202, and then processed by the processing unit located between the low-flow inlet 202 and the exhaust outlet 203 before being discharged from the second processing unit 2.

[0032] The second processing unit 2 includes an integrally sealed tank body 20, which is a high-temperature resistant and corrosion-resistant metal or ceramic composite structure. The interior is divided into multiple functional catalytic zones along the axial direction, and its structural design is closely matched with the dual-channel flow switching strategy.

[0033] Specifically, the high-flow inlet 201 and the exhaust outlet 203 are respectively located at both ends of the tank body 20, forming the main axis channel through which the exhaust gas flows through the second treatment unit 2; while the low-flow inlet 202 is precisely located on the side wall between the high-flow inlet 201 and the exhaust outlet 203, and is located in the middle and rear section of the catalytic zone inside the tank body 20, ensuring that the exhaust gas flowing in from the low-flow exhaust pipe 56 can directly enter the rear section of the second treatment unit 2 without directly contacting the front catalyst.

[0034] When the engine is operating under high flow conditions, the main channel valve is open and the bypass channel valve is closed. The high-temperature exhaust gas from the first treatment unit enters the tank body 20 through the high-flow exhaust pipe 200 and the high-flow inlet 201. It first flows through the front-end catalytic zone located between the high-flow inlet 201 and the low-flow inlet 202. This zone is filled with a high-cost, high-heat-resistant zeolite-type catalyst support (such as Cu-SSZ-13 or molecular sieve structure catalyst), which has excellent high-temperature activity and resistance to hydrothermal aging, and can efficiently catalyze high concentrations of NO. x The reduction reaction occurs at high temperatures. Subsequently, the exhaust gas continues to flow forward, entering the downstream catalytic zone located between the low-flow inlet 202 and the exhaust outlet 203. This zone is filled with a low-cost, low-temperature-activity iron / copper-based catalyst support (such as Fe-ZSM-5 or CuO-CeO2 systems) for further deep purification of residual NO. x This design leverages the advantages of both catalysts, working in tandem with the upstream stages to achieve highly efficient reduction throughout the entire process. It avoids the economic burden of using expensive zeolite-based materials uniformly throughout the entire process.

[0035] Under low-flow conditions, the main channel valve is closed and the bypass valve is open. The low-temperature, low-flow exhaust gas, after preliminary treatment by DOC and DPF, is directly injected into the middle and rear sections of the tank body 20 through the low-flow exhaust pipe 56 and low-flow inlet 202, completely bypassing the front-end zeolite catalyst. The exhaust gas only flows through the rear iron / copper-based catalyst layer between the low-flow inlet 202 and the exhaust outlet 203, where NO is eliminated. x The catalytic reduction of the exhaust gas followed by direct discharge is achieved. Because this pathway avoids the high specific surface area and high flow resistance of the zeolite-type carrier in the upstream section, the exhaust gas flow path inside the tank is shortened, the flow velocity is more stable, and turbulence is reduced, thus significantly reducing system back pressure and aerodynamic noise. Simultaneously, the iron / copper-based catalyst retains good activity at low temperatures, meeting the NO requirements under low flow conditions. x This addresses the conversion requirements and avoids problems such as the formation of "ineffective regions" in the catalyst or the deposition of urea crystals due to excessively slow airflow.

[0036] This structure, by strategically placing the low-flow inlet in the middle of the tank body rather than at the ends, achieves an intelligent control logic where "the location of the exhaust gas inlet determines the usable range of the catalytic zone," enabling the second processing unit to truly achieve "on-demand activation and zoned response." This not only improves the catalyst utilization rate at low flow rates but also extends the service life of high-priced zeolite catalysts.

[0037] In this application, the second processing unit 2 is an SCR processing unit, short for Selective Catalytic Reduction, which is a technology used in current diesel engine aftertreatment systems for the efficient removal of nitrogen oxides (NOx). xThe core technology of this technology involves using a reducing agent (usually a urea solution, i.e., automotive urea solution, abbreviated as AdBlue or DEF) to react with NO in the exhaust gas under the action of a catalyst. x A chemical reaction occurs, selectively converting it into harmless nitrogen (N2) and water (H2O), thereby reducing the NO content in the exhaust gas. x Deep purification to meet increasingly stringent emission regulations.

[0038] Furthermore, the tank body 20 contains multiple catalyst carriers arranged along the exhaust gas flow direction. These carriers are not made of a single material or have a homogeneous structure; rather, they are meticulously zoned and matched with materials according to operating conditions and temperature distribution characteristics, forming multi-segmented, functionally graded catalytic reaction zones to achieve NO reduction under different flow rates and temperatures. x Maximize restoration efficiency.

[0039] Furthermore, the catalyst support includes at least two of the following: SCR iron-based catalyst support, SCR copper-based catalyst support, and SCR zeolite-type catalyst support. The SCR iron-based and SCR copper-based catalyst supports are located in the tank between the low-flow inlet 202 and the exhaust outlet 203, while the SCR zeolite-type catalyst support is located in the tank between the high-flow inlet 201 and the low-flow inlet 202. This invention allows half of the SCR catalyst module to use a relatively inexpensive iron / copper-based catalyst for catalysis, reducing the cost of SCR.

[0040] Specifically, the interior of the tank is divided into two distinct functional areas: a front-end catalytic zone located between the high-flow inlet 201 and the low-flow inlet 202, which is equipped with a dedicated SCR zeolite catalyst carrier; and a rear-end catalytic zone located between the low-flow inlet 202 and the exhaust outlet 203, which is equipped with at least one of an SCR iron-based catalyst carrier and an SCR copper-based catalyst carrier, preferably a combination of the two.

[0041] SCR zeolite catalyst supports, preferably copper ion-exchanged SSZ-13 or CHA structured molecular sieves, are currently the highest-performing high-temperature catalysts in heavy-duty diesel vehicle SCR systems, exhibiting extremely high NO content in the 300–500℃ range. xIt boasts high conversion efficiency, excellent hydrothermal stability, and resistance to sulfur poisoning, making it particularly suitable for full-channel catalytic conversion under high load and high exhaust temperature. However, this material is expensive, and its catalytic activity significantly decreases at low temperatures (<200℃). Forcing it to participate in the reaction under low flow conditions not only results in low efficiency but also easily leads to severe ammonia escape and crystal deposition due to excessive urea injection. Therefore, this invention places the zeolite catalyst only in the front-end catalytic zone and activates it only under high flow conditions—when the main channel valve 52 is open and the bypass valve 55 is closed, the high-temperature, high-speed exhaust gas enters from the high-flow inlet 201, first flowing through this zone, where the zeolite catalyst efficiently completes the NO conversion. x Its primary and main reduction tasks, and its high activity ensure that it can perform high concentrations of NO. x Under certain conditions, it achieves a conversion rate of over 95%, meeting the peak operating requirements of stringent emission regulations.

[0042] In the downstream catalytic zone between the low-flow inlet 202 and the exhaust outlet 203, this invention employs a combination of an SCR iron-based catalyst support and an SCR copper-based catalyst support. The iron-based catalyst support, such as Fe-ZSM-5 or Fe-SSZ-13 modified materials, exhibits good low-temperature activity (ignition temperature 160–180℃) and is effective for low concentrations of NO. x The conversion efficiency is high, and the sulfur resistance is superior to that of traditional vanadium-based catalysts; copper-based catalyst supports such as CuO-CeO2, Cu / Al2O3, or low-temperature modified Cu-SSZ-13 have a wide temperature range catalytic window and excellent NH3 adsorption capacity in the 180–300℃ range, making them particularly suitable for handling low flow rates, low temperatures, and low NO content. x The concentration varies depending on idling or urban driving conditions. This area does not use high-cost zeolite-type materials, but instead utilizes the synergistic effect of iron-based and copper-based materials: the iron-based material acts as the "basic catalyst layer," bearing the main responsibility for NO concentration. x In the reduction task, the copper-based layer serves as an "activity enhancement layer," improving the low-temperature response speed and ammonia utilization efficiency. The combination of the two forms a low-temperature catalytic module that is cost-effective, reliable in performance, and widely adaptable.

[0043] When the engine is operating at low flow rates, the bypass valve 55 opens and the main valve 52 closes. The low-temperature, low-speed exhaust gas no longer flows through the high-temperature front section, but instead enters the SCR rear section directly through the low-flow exhaust pipe 56 and the low-flow inlet 202. At this time, the exhaust gas only passes through the iron / copper-based catalyst layer in the rear section. The catalyst in this region maintains highly efficient catalytic activity within this temperature range (170–280℃), enabling it to process low-concentration NO with extremely low urea injection rates. xEffective conversion. More importantly, because this area only processes a small portion of the exhaust volume (relative to the full flow channel), and the catalyst is smaller and the flow channel is more compact, the system back pressure is significantly reduced, heat loss is decreased, and noise levels are consequently lowered. At the same time, since the front-end zeolite catalyst is not involved in the operation, it is protected from the erosion of low-temperature moisture and urea crystals, greatly delaying the thermal aging and hydrothermal deactivation process, and significantly extending the service life of the entire SCR system.

[0044] This asymmetric catalyst layout completely overturns the traditional design thinking of "full-section zeolite" or "homogeneous mixing". The former is costly, has poor low-temperature efficiency, and rapid lifespan loss; the latter, while accommodating a wide temperature range, suffers from low catalyst utilization and persistently high costs. This invention, by using high-cost, high-performance materials only in the high-temperature, high-load region and low-cost, low-temperature high-performance materials in the low-load region, achieves material economics by "using the best materials where they are most needed". At high flow rates, the zeolite catalyst "primarily targets" high concentrations of NO. x At low flow rates, iron / copper-based catalysts provide a safety net for low concentrations of NO. x The two complement each other, each performing its specific function without redundancy or waste. This structural design is naturally suited to the dual-channel flow control mechanism of this invention. The introduction of the low-flow path makes the SCR downstream section a "dedicated independent catalytic unit for low loads," no longer limited by the operational requirements of the high-temperature upstream zone. This not only improves the overall volumetric utilization rate of the catalyst—at low flow rates, the "front half" of the SCR is no longer idle space but a "dormant zone" actively isolated and protected—but also fundamentally solves the systemic problems of insufficient catalyst utilization, high back pressure, high noise, and high ammonia escape risk caused by the "large chamber, low flow rate" of traditional SCR systems at low loads.

[0045] In summary, this invention constructs a "function-oriented, condition-responsive" partitioned catalytic structure by placing the SCR iron-based and copper-based catalysts in the latter stage and the zeolite catalyst in the former stage. This not only achieves scientific configuration and cost optimization of catalyst materials but also transforms the SCR system from a "passive adaptation to operating conditions" to an "active matching to operating conditions" intelligent unit. This design not only extends catalyst life, reduces total system cost, and reduces the risk of ammonia escape, but also provides a scalable platform foundation at the structural level for future next-generation aftertreatment technologies such as multi-material synergy, intelligent regeneration, and adaptive catalysis. This is one of the most core technological innovations of this invention. In another specific embodiment, the SCR iron-based catalyst support, SCR copper-based catalyst support, and SCR zeolite catalyst support can be replaced with vanadium, platinum catalysts, or other transition metal oxide catalysts. Vanadium-based catalysts, such as vanadium pentoxide (V₂O₅) supported on titanium tungsten oxide (TiO₂–WO₃–V₂O₅) supports, are traditional materials widely used in early diesel vehicle SCR systems. Its advantages lie in its low cost, good low-temperature activity (ignition temperature of about 200℃), and low dependence on NO2, making it suitable for medium and low speed operating conditions.

[0046] Furthermore, it also includes: ASC processing unit 3, the inlet of ASC processing unit 3 is connected to exhaust gas outlet 203, and the outlet of ASC processing unit 3 is connected to the atmospheric environment.

[0047] The ASC treatment unit 3 typically uses precious metals (such as platinum (Pt) and palladium (Pd) or transition metal oxides (such as Mn-Ce-O and Co3O4) as active components, loaded onto a ceramic or metal support with a high specific surface area. Its operating temperature window is generally between 200 and 450°C, which is highly matched with the exhaust temperature after the SCR. When the exhaust gas flows out of the exhaust outlet 203 of the second treatment unit 2, although the main NOx reduction reaction has been completed, a small amount of unreacted ammonia (NH3) may still escape with the exhaust gas due to deviations in urea injection control, temperature fluctuations, catalyst aging, or transient conditions. If left untreated, this ammonia will be directly released into the atmosphere, not only producing a pungent odor and affecting the environment and human health, but also potentially reacting with nitrogen oxides in the atmosphere to generate secondary particulate matter (PM2.5), which defeats the purpose of emission reduction. The ASC treatment unit 3 uses a catalytic oxidation mechanism to react the escaped NH3 with the residual oxygen in the exhaust gas on the catalyst surface to generate harmless nitrogen (N2) and water vapor (H2O). In the system of this invention, the ASC is deployed close to the SCR outlet, forming the "last line of defense" of the aftertreatment system. Its inlet is directly connected to the SCR exhaust outlet 203, avoiding heat loss caused by long exhaust pipes, ensuring that the ASC is always in the high-efficiency operating temperature range, and achieving rapid ignition without the need for additional heating devices.

[0048] ASC, short for Ammonia Slip Catalyst, is an indispensable end-of-pipe purification unit in modern diesel vehicle aftertreatment systems. Its core function is to catalytically oxidize and eliminate unreacted ammonia (NH3) escaping from the SCR system, ensuring that the ammonia concentration in the exhaust gas finally released into the atmosphere meets regulatory limits (such as the stringent requirements for NH3 emissions in standards like China VIb, Euro VI, and EPA Tier 3).

[0049] Furthermore, at least one of the following is provided at the exhaust gas inlet 11: a flow sensor 41, a nitrogen oxide sensor 42, a temperature sensor 43, and a differential pressure sensor 44; and / or, an NH3 sensor 45 and a NO sensor 46 are provided at the outlet of the ASC treatment unit 3. x At least one of the sensors 46.

[0050] At the exhaust gas inlet 11, the flow sensor 41 is used to monitor the instantaneous exhaust mass flow rate or volume flow rate entering the aftertreatment system in real time. Its signal is the core basis for the ECU4 to determine the current operating condition of the engine (such as idling, low load, medium and high load). Based on this flow rate value, combined with preset threshold logic (such as 50% of the maximum flow rate), the ECU decides whether to open or close the bypass valve 55 to realize the intelligent switching of the SCR catalyst zone.

[0051] Nitrogen oxide sensor 42 directly measures the raw NO entering the aftertreatment system. x The concentration provides a reference input for the initial calculation of urea injection quantity, enabling the ECU to calculate the urea injection quantity based on the upstream NO concentration. x The dynamic adjustment of the injection strategy based on the load avoids "over-injection" or "under-injection," thereby reducing the risk of ammonia escape while ensuring purification efficiency.

[0052] Temperature sensor 43 is used to monitor exhaust inlet temperature. This data is used not only to determine whether the SCR has the conditions for ignition (such as whether it is above 180°C), but also to correct the pyrolysis efficiency model of urea, prevent crystal deposition caused by low temperature injection, and provide thermodynamic basis for bypass valve switching strategy. For example, in the cold start stage, even if the flow rate is small, if the exhaust temperature is insufficient, the system can still temporarily not use bypass and prioritize relying on DOC / DPF to raise the temperature. After the temperature reaches the standard, it can switch to energy-saving mode.

[0053] Differential pressure sensors 44 are installed at both ends of the first processing unit 1 to continuously monitor the back pressure difference generated during particulate matter capture, providing key criteria for DPF regeneration control. When the differential pressure exceeds the set threshold, the ECU can actively trigger the after-injection or electric heating regeneration program to ensure long-term efficient operation of the DPF and avoid affecting the intake uniformity and catalytic efficiency of the downstream SCR due to blockage.

[0054] At the outlet of ASC processing unit 3, NH3 sensor 45 and NO x Sensor 46 constitutes the "final arbiter" of system emissions. NH3 sensor 45 employs electrochemical sensing or laser absorption spectroscopy technology to accurately measure the residual ammonia concentration in the exhaust gas. Its value directly reflects the ammonia conversion efficiency of the SCR system and the purification capacity of the ASC. When the NH3 concentration remains above the regulatory limit (e.g., 10 ppm), the ECU immediately activates a compensation mechanism, reducing the urea injection amount or extending the ASC operating time to enhance oxidation efficiency. If a sudden drop in NH3 concentration or even zero is detected, it may indicate insufficient urea injection or catalyst failure; the ECU will then issue a fault warning and enter a safe mode.

[0055] NO x Sensor 46 is used to verify the residual level of nitrogen oxides in the final exhaust gas, serving as the "ultimate indicator" for measuring the overall purification effect of the entire aftertreatment system. The signal from this sensor is compared with that from the imported nitrogen oxide sensor 42 to calculate the overall system conversion efficiency, providing feedback for the ECU to make corrections. For example, if the imported NO… x High but export NO x If the NO concentration does not decrease significantly, the ECU can determine that the activity of the SCR front-end catalyst has decreased, requiring increased urea injection or triggering of the self-diagnostic mechanism; if the outlet NO... x If both NH3 and NH3 are elevated, it indicates a control mismatch in the system, requiring multi-parameter collaborative optimization.

[0056] These two sensor networks do not operate in isolation, but rather achieve data fusion and cross-validation through ECU4: the inlet-end sensors are used for "predictive control," predicting the optimal operating strategy based on upstream conditions; the outlet-end sensors are used for "closed-loop correction," achieving real-time correction of actual emission results. This "feedforward + feedback" dual-mode control architecture greatly improves the robustness and stability of the system under complex transient conditions (such as acceleration, deceleration, ramping, and idling). Especially in the variable flow mode of this invention, when valves frequently switch and airflow distribution changes drastically, the sensor network can quickly capture fluctuations in NH3 concentration or NO. x The declining conversion efficiency prompts the ECU to respond within milliseconds, dynamically adjusting the urea injection timing, injection quantity, and bypass valve opening to ensure that the system is always in optimal operating condition, whether in high-flow full-channel mode or low-flow bypass mode.

[0057] Furthermore, the ECU can also record the historical response curves of each sensor, identify abnormal trends such as sensor drift, catalyst aging, and urea pump performance degradation, provide early warnings of maintenance needs, and extend the overall service life of the aftertreatment system.

[0058] Furthermore, the engine exhaust gas treatment system also includes: a urea tank 25; a urea pump 24, the inlet end of which is connected to the urea tank 25, and the outlet end of the urea pump 24 is provided with a main channel urea nozzle 23 and a bypass channel urea nozzle 27. The main channel urea nozzle 23 is connected to the high-flow exhaust pipe 200, and the bypass channel urea nozzle 27 is connected to the low-flow exhaust pipe 56.

[0059] The engine exhaust gas treatment system of the present invention is also equipped with a complete urea supply and precision injection system, including a urea tank 25, a urea pump 24, a main channel urea nozzle 23 and a bypass channel urea nozzle 27, forming an independent, controllable, dual-path collaborative urea injection architecture.

[0060] The urea tank 25 is a corrosion-resistant, heat-insulating, sealed liquid storage container used to store a 32.5% high-purity automotive urea solution (AdBlue). It integrates a liquid level sensor, a temperature sensor, and a heating device to ensure the urea solution does not freeze or crystallize in low-temperature environments, maintaining its physical stability and chemical activity. When the ambient temperature drops below -10°C, the built-in heating element automatically activates, maintaining the urea solution within the pumpable range of 5–30°C, ensuring rapid response during system cold starts. The outlet of the urea tank 25 is directly connected to the inlet of the urea pump 24 via an anti-backflow pipeline, ensuring a clean and airtight supply path and preventing pressure fluctuations caused by air bubble intake.

[0061] The urea pump 24 is a high-pressure positive displacement metering pump with precise flow regulation capabilities. It can continuously and stably pressurize and deliver urea solution to the downstream nozzle within a pressure range of 5–100 bar. Its core consists of a stepper motor-driven plunger or diaphragm structure, and is controlled by the ECU using pulse width modulation (PWM) based on real-time operating conditions to achieve millisecond-level precise control of the injection volume. Unlike traditional single injection paths, the outlet of the urea pump 24 in this system adopts a branched design, connecting both the main channel urea nozzle 23 and the bypass channel urea nozzle 27. This allows the urea solution to be delivered to the mixing area of ​​the main channel and the bypass channel respectively, depending on the different exhaust flow paths, realizing a "dual-path independent injection" strategy.

[0062] The main channel urea nozzle 23 is installed inside the high-flow exhaust pipe 200, located in the main exhaust channel after the first treatment unit 1 and before the second treatment unit 2. When the engine is under medium-high load and high flow conditions, the high-temperature and high-pressure exhaust gas enters the SCR through the main channel. At this time, the ECU synchronously commands the urea pump 24 to supply liquid to the main channel urea nozzle 23. The urea solution is atomized and directly injected into the high-speed airflow. Subsequently, it works in conjunction with the main channel mixer 26 to achieve full mixing of urea droplets and exhaust gas, ensuring uniform ammonia distribution and providing sufficient reducing agent for the front-end zeolite catalyst and the rear-end iron / copper-based catalyst to meet the requirements of high-concentration NO. xThe deep transformation needs.

[0063] The bypass urea nozzle 27 is installed inside the low-flow exhaust pipe 56, located in a side branch of the low-flow exhaust pipe 56 near the inlet of the second treatment unit 2. When the engine is idling, under low load, and with low flow, the low-temperature, low-speed exhaust gas bypasses the front section of the SCR and directly enters the catalytic converter zone of the SCR rear section through the low-flow exhaust pipe 56. At this time, the ECU determines that it is a low-temperature, low-flow condition, shuts off the main channel injection, and only activates the bypass urea nozzle 27 to precisely inject urea solution into the bypass airflow. Due to the narrow diameter and low flow velocity of the bypass path, the urea droplets, under the disturbance of the bypass mixer 28, obtain a longer evaporation and diffusion time, significantly improving the urea pyrolysis efficiency and NH3 distribution uniformity, avoiding local urea crystallization or the formation of a "dry zone" in the catalytic converter zone due to poor mixing. At the same time, since this path only flows through the iron / copper-based catalyst in the rear section of the SCR, its low-temperature activity can efficiently utilize the ammonia injected into this area to achieve stable NO under low flow conditions. x It reduces ammonia levels without requiring a large dose of injection into the entire SCR chamber, effectively avoiding the risk of ammonia escape.

[0064] The dual-nozzle independent control design eliminates the "one-size-fits-all" approach to urea injection, enabling precise response based on "flow rate-path-catalyst matching." At high flow rates, the main channel injection covers the entire SCR process, ensuring efficient conversion. At low flow rates, the bypass channel injection serves only the downstream catalytic zone, reducing the total injection volume and lowering ammonia consumption and escape risk. The ECU establishes a three-dimensional mapping model of "operating condition-injection quantity-injection path" by integrating signals from the flow sensor 41, temperature sensor 43, and NOx sensor 42, achieving a dynamically optimal injection strategy. For example, in the medium flow transition zone, the ECU can employ a combined main and bypass channel injection mode with proportional coordination to achieve smooth switching and avoid control jumps.

[0065] Furthermore, the urea pump 24 and the dual-nozzle system also possess self-diagnostic and fault isolation capabilities. If the main channel urea nozzle 23 becomes clogged or leaks, the ECU can switch to bypass mode and trigger power limiting protection; if the bypass channel urea nozzle 27 fails, the system can still maintain full flow operation in the main channel to ensure emission compliance. This redundancy design greatly improves the system's reliability and robustness.

[0066] Furthermore, a main channel mixer 26 is installed in the pipeline between the main channel urea nozzle 23 and the high-flow inlet 201, and a bypass channel mixer 28 is installed in the pipeline between the bypass channel urea nozzle 27 and the low-flow inlet 202. Additionally, valve structures are installed in both the high-flow exhaust pipeline 200 and the low-flow exhaust pipeline 56. To ensure that the urea solution is fully vaporized, pyrolyzed, and uniformly dispersed in the high-temperature exhaust flow to form a stable and homogeneous ammonia-tail gas mixture, this invention installs a main channel mixer 26 and a bypass channel mixer 28 in the key flow channels between the urea injection point and the SCR inlet, respectively. Independent valve structures are also configured in both the high-flow exhaust pipeline 200 and the low-flow exhaust pipeline 56, collaboratively achieving intelligent switching of the airflow path and ultimate optimization of mixing efficiency.

[0067] Specifically, in this embodiment, a main channel valve 52 is provided in the high-flow exhaust pipe 200, and a bypass channel valve 55 is provided in both the low-flow exhaust pipe 56.

[0068] Specifically, the valves do not necessarily have to be in two states: open and closed. The opening angle of the main channel valve and the bypass channel valve can also be set to have a functional relationship with the exhaust flow rate.

[0069] The main channel mixer 26 is located between the main channel urea nozzle 23 and the high-flow inlet 201, within the high-flow exhaust pipe downstream of the first treatment unit 1 and upstream of the second treatment unit 2. Its structure comprises porous guide plates, spiral vortex vanes, or honeycomb-type turbulence elements. When high-temperature exhaust gas (typically between 250 and 450°C) flows at high speed through this area, the mixer creates localized turbulence and vortices through forced disturbance, ensuring that the urea droplets ejected from the main channel urea nozzle 23 fully contact, collide, break up, and evaporate with the high-speed airflow in a very short time. This design significantly shortens the reaction path of urea pyrolysis into NH3 and CO2, preventing droplets from condensing, depositing, or forming "wet zones" on the pipe wall, thus eliminating the risk of crystallization blockage caused by incomplete local urea decomposition. Most importantly, the design of the main channel mixer 26 fully considers the high Reynolds number flow characteristics under high flow conditions. Its geometry is optimized by CFD to achieve a mixing uniformity index (MUI) of over 0.9, ensuring that the NH3 concentration distribution deviation of the zeolite catalyst entering the SCR front section is less than 5%, laying the foundation for high-efficiency and high-selectivity catalytic reactions.

[0070] The bypass mixer 28 is located between the bypass urea nozzle 27 and the low-flow inlet 202, in a narrow channel of the low-flow exhaust pipe near the SCR downstream inlet. Unlike the high-flow exhaust pipe, the exhaust velocity in the low-flow exhaust pipe is significantly reduced, especially at idle or low load conditions, where the airflow velocity may be less than 1 / 3 of that in the main channel. Without an efficient mixing structure, urea droplets are prone to settling on the pipe wall due to excessive residence time, or uneven mixing may lead to excessively high local NH3 concentrations, causing "ammonia hotspots" in the downstream catalyst or even secondary oxidation to NO. x To address this, the bypass mixer 28 employs a high-density fine-toothed turbulence structure or a multi-stage Venturi diffuser-contraction combination design. By locally narrowing the diameter, it enhances the airflow shear force, generating strong local vortices and recirculation zones as the low-speed airflow passes through the mixer. This effectively prolongs the suspension time of urea droplets in the gas phase, improving evaporation efficiency. Simultaneously, it is made of high-temperature resistant, low-surface-energy ceramic-coated stainless steel, which is both corrosion-resistant and reduces urea residue adhesion. The presence of this mixer ensures that, despite the low flow rate and temperature in the bypass path, it achieves mixing uniformity comparable to the main channel, guaranteeing a stable and controllable supply of reducing agent to the iron / copper-based catalyst zone and preventing a sharp drop in purification efficiency due to mixing degradation.

[0071] To achieve precise switching and dynamic control of the exhaust flow path, this invention incorporates independent valve structures in both the high-flow exhaust pipe 200 and the low-flow exhaust pipe 56: a main channel valve 52 and a bypass channel valve 55, respectively. Both are high-temperature resistant, high-sealing, and fast-response pneumatic or electric butterfly / flap valves. Their outer shells are made of double-layered heat-insulated stainless steel, and the internal valve plates are treated with a ceramic coating, enabling them to withstand long-term high temperatures above 550℃ and exhaust particle erosion. The main channel valve 52 is installed upstream of the high-flow exhaust pipe 200, controlling whether exhaust gas flows into the SCR pre-stage; the bypass channel valve 55 is installed at the inlet of the low-flow exhaust pipe 56, controlling whether exhaust gas bypasses the main channel and directly enters the SCR post-stage. Both valves employ interlocking logic control to ensure that only one channel is open at any given time, preventing airflow short-circuiting or mixing interference.

[0072] The ECU uses flow sensor 41, temperature sensor 43, and NO... x The real-time data from sensor 46 dynamically determines the valve opening and closing status. Under low-flow conditions (such as idling and city cruising), the ECU closes the main channel valve 52 and opens the bypass valve 55, allowing all exhaust gas to enter the SCR downstream via the bypass path. Simultaneously, only the bypass urea nozzle 27 and bypass mixer 28 are activated, achieving energy-saving operation with low back pressure, low heat loss, and low noise. Under medium-to-high flow conditions (such as high-speed cruising and heavy-load hill climbing), the ECU closes the bypass valve 55 and opens the main channel valve 52, allowing all exhaust gas to flow through both the SCR upstream and downstream stages. Simultaneously, the main channel urea nozzle 23 and main channel mixer 26 work together to achieve high-efficiency NO2 across the entire flow path.x Restoration. During transitional operating conditions, the ECU can use a gradual opening adjustment—such as the main channel valve 52 gradually opening from 20% to 80%, while the bypass channel valve 55 closes simultaneously, so that the airflow and injection volume transition smoothly, avoiding system fluctuations and sudden changes in emissions.

[0073] The main channel mixer 26, the bypass channel mixer 28, the main channel valve 52, and the bypass channel valve 55 work together to form a three-in-one linkage control system of "airflow path selection – injection point positioning – mixing quality assurance". The valves determine "where the gas goes", the nozzles determine "where the reducing agent is added", and the mixers determine "whether the addition is uniform". This highly integrated structural design not only achieves spatial decoupling and operating condition adaptation between the exhaust flow and the urea flow, but also, through precise fluid dynamics optimization, enables the system to maintain high catalytic efficiency, low pressure loss, low ammonia escape, and low noise under all operating conditions, completely breaking the inherent defects of traditional single-channel aftertreatment systems in low-flow conditions, such as "low efficiency, high back pressure, high noise, and short lifespan".

[0074] According to another aspect of the present invention, a vehicle is provided having an engine exhaust gas treatment system, which is the engine exhaust gas treatment system described above.

[0075] The working principle of the engine exhaust gas treatment system using the technical solution of this embodiment is as follows: When the engine is running, the exhaust gas enters the first treatment unit 1, where HC and CO are oxidized to H2O and CO2 in DOC, NO is partially oxidized to NO2, and PM is captured by DPF. When ECU4 determines that the exhaust flow rate is lower than a set threshold (e.g., 50% of the maximum flow rate, which can be adjusted according to actual conditions) through flow sensor 41, nitrogen oxide sensor 42, and temperature sensor 43, ECU controls the main channel valve 52 to close and the bypass channel valve 55 to open, and simultaneously starts the bypass channel urea nozzle 27 to spray urea solution into the low-flow exhaust pipe 56. After the urea solution and exhaust gas are fully mixed in the low-flow exhaust pipe 56 by the bypass channel mixer 28, it is directly introduced into the latter half of the second treatment unit 2, flowing only through the iron / copper-based catalyst carrier. At this time, NOx in the low-temperature, low-flow exhaust gas undergoes a selective catalytic reduction reaction on the surface of the iron / copper-based catalyst carrier, generating N2 and H2O. Because the exhaust gas only flows through the latter half of the SCR system and bypasses the zeolite catalyst carrier in the first half, exhaust flow resistance is significantly reduced, back pressure and heat loss are decreased, and aftertreatment system noise is also reduced. When the ECU detects that the exhaust flow exceeds a set threshold, the ECU controls the bypass valve 55 to close and the main channel valve 52 to open, while simultaneously activating the main channel urea nozzle 23 to inject urea solution into the high-flow exhaust pipe. After the urea solution is uniformly mixed with the exhaust gas by the main channel mixer 26, it enters the first half of the second treatment unit 2, first flowing through the zeolite catalyst carrier and then through the iron / copper-based catalyst carrier. At this point, the high concentration of NOx in the high-temperature, high-flow exhaust gas is preferentially catalytically reduced by the zeolite catalyst carrier, and the iron / copper-based catalyst carrier acts as a secondary catalytic layer to further improve conversion efficiency. After the exhaust gas has completely passed through the second treatment unit 2, it enters the ASC treatment unit 3, where unreacted NH3 is catalytically oxidized to N2 and H2O, and finally discharged into the atmosphere.

[0076] The ECU continuously receives NH3 and NO signals from the output of the ASC processing unit 3. x The feedback signal from sensor 46 dynamically adjusts the liquid supply pressure of urea pump 24 and the injection volume of urea nozzle. If the NOx emission concentration is higher than the set threshold, the ECU increases the urea injection volume; if the NH3 escape concentration exceeds the standard, the ECU reduces the urea injection volume, achieving a precise balance between NOx purification efficiency and NH3 emissions.

[0077] DPF Regeneration Process (Auxiliary Use Process): When the differential pressure sensor 44 detects that the differential pressure across the first processing unit 1 exceeds a preset threshold, the ECU determines that the DPF has severe carbon buildup and initiates the regeneration mode. The ECU controls the engine's fuel injection strategy or activates the electric heating device to raise the exhaust temperature to above 600°C, causing the PM accumulated in the DPF to burn and oxidize into CO2 in an oxygen-rich environment, achieving passive or active regeneration. During the regeneration process, the main channel valve 52 remains open, while the bypass channel valve 55 is closed, ensuring that all exhaust flows through the DPF, maintaining the stable airflow and temperature field required for regeneration, and avoiding a decrease in regeneration efficiency due to a bypass path.

[0078] System switching and state maintenance process: During dynamic changes in engine operating conditions, such as increasing from idle speed to medium load, the ECU uses fuzzy logic or PID algorithm to implement gradual opening and closing control of the main channel valve 52 and the bypass channel valve 55 based on the instantaneous change rate of the flow sensor 41 and the response trend of the temperature sensor 43. This avoids exhaust fluctuations or urea injection pulse interference caused by sudden valve changes. During steady-state operation, the ECU maintains stable valve states to ensure the continued effectiveness of the SCR catalyst zoned usage mode, extend the service life of the zeolite catalyst support in the high-temperature region, and improve the catalytic activity utilization rate of the iron / copper-based catalyst support in the low-temperature region.

[0079] Safe operation under system failure or abnormal conditions: If the flow sensor 41 or temperature sensor 43 signals abnormally, the ECU enters a safety protection mode: by default, the main channel valve 52 is opened and the bypass channel valve 55 is closed, forcing the exhaust gas to pass through the second processing unit 2 in full to ensure that the NOx reduction function is not interrupted; at the same time, the redundant nitrogen oxide sensor 42 and NH3 sensor 45 data cross-verification are enabled, and a fault alarm is triggered. If the urea pump 24 or urea injector fails, the ECU stops injection and uses historical data to estimate urea demand, maintaining minimum catalytic efficiency and avoiding excessive NH3 escape.

[0080] The application of the technical solution of this application has the following beneficial effects: 1. In traditional SCR systems, under low-flow conditions, due to the small exhaust flow and low velocity, the exhaust gas only passes through the front end of the catalyst, leaving the large rear catalytic zone essentially "idling," resulting in a chamber utilization rate of less than 30%. This invention, by adding a bypass pipe and intelligent valve control, allows low-flow exhaust gas to bypass the front section of the SCR and directly enter the rear catalytic zone, forcibly utilizing the previously idle rear half of the catalyst space. This increases the effective catalytic volume utilization rate of the SCR under low-flow conditions to over 70%, achieving optimized catalytic resource allocation for "all operating conditions, all spaces, and high efficiency," significantly reducing the catalyst volume required per unit processing capacity and the system cost.

[0081] 2. In traditional systems, when the exhaust gas is forced through a complete SCR at low flow rates, the high pore density and small flow area of ​​the catalyst carrier lead to a sharp increase in local pressure drop, resulting in a 20%–40% increase in exhaust back pressure. This not only affects engine fuel economy but also causes resonance in the aftertreatment housing, producing high-frequency whistling and low-frequency roaring. This invention diverts low-flow exhaust gas through a bypass path, allowing the airflow to pass only through a smaller diameter but lower flow resistance bypass pipe and the downstream catalyst. The overall flow resistance is reduced by more than 30%, effectively suppressing the increase in back pressure. At the same time, it reduces turbulence and vortex noise in the sealed catalytic module, lowering the noise level of the aftertreatment system by 5–8 dB(A), significantly improving vehicle comfort and NVH performance.

[0082] 3. This invention places the zeolite catalyst only in the front section of the high-flow-rate main channel, ensuring it operates only under high-temperature (>300℃) and high-flow-rate conditions, thus avoiding abnormal stress and chemical corrosion under low-temperature conditions. Simultaneously, the downstream iron / copper-based catalyst, with its lower cost and better low-temperature resistance, bears the main low-temperature load, protecting high-value materials. Through this "division of labor and zoned isolation," the lifespan of the zeolite catalyst is extended by more than 40%, and the overall SCR system replacement cycle can be extended to over 1.2 million kilometers, significantly reducing user maintenance costs.

[0083] 4. This invention guides the exhaust gas through a bypass path to concentrate it through a low-temperature, highly active iron / copper-based catalyst zone, and, in conjunction with a dedicated bypass mixer and precise injection, makes the NH3 distribution more uniform and the reaction more complete.

[0084] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0085] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0086] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An engine exhaust gas treatment system, characterized in that, include: The first processing unit (1) has an exhaust gas inlet (11), a large flow outlet (12), and a small flow outlet (13). The second processing unit (2) has a large flow inlet (201) and a small flow inlet (202), and an exhaust outlet (203). The large flow outlet (12) is connected to the large flow inlet (201) to form a large flow exhaust pipe (200), and the small flow outlet (13) is connected to the small flow inlet (202) to form a small flow exhaust pipe (56). The small flow inlet (202) is located between the large flow inlet (201) and the exhaust outlet (203). The exhaust gas flowing into the second processing unit (2) from the small flow exhaust pipe (56) is processed by the processing unit located between the small flow inlet (202) and the exhaust outlet (203) and then discharged from the second processing unit (2).

2. The engine exhaust gas treatment system according to claim 1, characterized in that, The second processing unit (2) includes a tank body (20), the high-flow inlet (201) and the exhaust outlet (203) are respectively disposed on two opposite ends of the tank body (20), and the low-flow inlet (202) is located between the high-flow inlet (201) and the exhaust outlet (203). The exhaust gas entering the tank body (20) from the high-flow exhaust pipe (200) is processed by the processing unit located between the high-flow inlet (201) and the low-flow inlet (202), and then discharged from the second processing unit (2) after being processed by the processing unit located between the low-flow inlet (202) and the exhaust outlet (203).

3. The engine exhaust gas treatment system according to claim 2, characterized in that, The tank body (20) is provided with a variety of catalyst carriers, which are arranged along the exhaust gas flow direction.

4. The engine exhaust gas treatment system according to claim 3, characterized in that, The catalyst supports include at least two of the following: SCR iron-based catalyst support, SCR copper-based catalyst support, and SCR zeolite-type catalyst support. The SCR iron-based catalyst support and the SCR copper-based catalyst support are located in a tank between the low-flow inlet (202) and the exhaust gas outlet (203), and the SCR zeolite-type catalyst support is located in a tank between the high-flow inlet (201) and the low-flow inlet (202).

5. The engine exhaust gas treatment system according to any one of claims 1 to 4, characterized in that, Also includes: The ASC processing unit (3) has its inlet connected to the exhaust outlet (203) and its outlet connected to the atmospheric environment.

6. The engine exhaust gas treatment system according to claim 5, characterized in that, At least one of the following is provided at the exhaust gas inlet (11): a flow sensor (41), a nitrogen oxide sensor (42), a temperature sensor (43), and a differential pressure sensor (44); and / or, an NH3 sensor (45) and a NO sensor (46) are provided at the outlet of the ASC processing unit (3). x At least one of the sensors (46).

7. The engine exhaust gas treatment system according to claim 5, characterized in that, Also includes: Urea tank (25); The urea pump (24) has its inlet end connected to the urea tank (25), and its outlet end is provided with a main channel urea nozzle (23) and a bypass channel urea nozzle (27). The main channel urea nozzle (23) is connected to the high flow exhaust pipe (200), and the bypass channel urea nozzle (27) is connected to the low flow exhaust pipe (56).

8. The engine exhaust gas treatment system according to claim 7, characterized in that, A main channel mixer (26) is provided in the pipeline between the main channel urea nozzle (23) and the high flow rate inlet (201), and a bypass channel mixer (28) is provided in the pipeline between the bypass channel urea nozzle (27) and the low flow rate inlet (202), and / or, valve structures are provided in both the high flow rate exhaust pipeline (200) and the low flow rate exhaust pipeline (56).

9. The engine exhaust gas treatment system according to claim 1, characterized in that, The first processing unit (1) includes an oxidation catalyst unit and a particulate trap unit.

10. A vehicle, characterized in that, The vehicle has an engine exhaust treatment system, which is the engine exhaust treatment system according to any one of claims 1-9.

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