Double-spraying SCR aftertreatment system and vehicle

Abstract

The embodiment of the invention provides a double-spraying SCR aftertreatment system and a vehicle. According to the system, secondary trapping of particulate matter discharged by an engine and particulate matter newly generated by a second ammonia injection module is achieved through a second particulate matter trapping module arranged at the tail end of a post-treatment system; meanwhile, in order to avoid the situation that the size of the aftertreatment system can be increased by the additionally arranged second particle trapping module, and the spatial arrangement of the aftertreatment system on the whole vehicle is affected, the particle trap is coated with an SCR catalyst or an ASC catalyst, the selective catalytic reduction function and the ammonia trapping function are integrated, and the overall performance of the whole vehicle is improved. Therefore, on the basis that emission of nitric oxide and particulate matter reaches the standard, the size and the cost of an existing post-treatment system are not increased, and pollutants emitted by tail gas of the vehicle are further reduced.

Description

Technical Field

[0001] The present application relates to the field of engine control technology, and in particular to a dual-injection SCR after-treatment system and a vehicle. Background Art

[0002] With the continuous improvement of environmental protection requirements, the requirements for the emission of nitrogen oxides and particulate matter in motor vehicle exhaust pollutants are becoming increasingly stringent. Therefore, the dual-injection SCR (Selective Catalytic Reduction) post-treatment solution has become the main vehicle exhaust treatment solution at present;

[0003] The existing dual-injection SCR after-treatment solution includes a front-stage SCR and a rear-stage SCR. However, in order to protect the passive regeneration capability of the downstream DPF (Diesel Particulate Filter), the urea injection corresponding to the front-stage SCR will be appropriately reduced when the exhaust gas temperature is high. At this time, the rear-stage SCR needs to inject sufficient or even excessive urea to improve the nitrogen oxide removal efficiency.

[0004] However, when excessive urea is injected into the post-stage SCR, the number of large-diameter particles in the exhaust gas will increase, thereby increasing the risk of excessive particle emissions in the exhaust gas. Summary of the invention

[0005] The embodiments of the present application provide a dual-injection SCR post-treatment system and a vehicle, which are used to solve the defect of the existing dual-injection SCR post-treatment scheme that the risk of excessive particulate matter emissions in the exhaust gas increases due to excessive urea injection into the rear-stage SCR.

[0006] In a first aspect, an embodiment of the present application provides a dual-injection SCR post-treatment system, comprising:

[0007] A first ammonia injection module is located downstream of the exhaust outlet of the engine and is used to perform a first ammonia injection into the exhaust gas discharged from the exhaust outlet;

[0008] A first reduction catalytic module, located downstream of the first ammonia injection module, is used for first catalytically reducing nitrogen oxides in the exhaust gas with the assistance of the ammonia substance and capturing residual ammonia substances;

[0009] An oxidation catalytic capture module, located downstream of the first reduction catalytic module, is used to oxidize carbon monoxide, hydrocarbons, and nitrogen monoxide in the exhaust gas, and to capture and oxidize particulate matter in the exhaust gas for the first time;

[0010] A second ammonia injection module, located downstream of the oxidation catalytic capture module, is used to inject ammonia material into the tail gas for the second time;

[0011] A second reduction catalytic module, located downstream of the second ammonia injection module, is used for performing a second catalytic reduction of nitrogen oxides in the exhaust gas with the assistance of the ammonia substance;

[0012] The second particle trap module is located downstream of the second reduction catalytic module and is used for a second capture and oxidation of particulate matter in the exhaust gas.

[0013] In one possible embodiment, the second reduction catalytic module includes a second SCR module, the second particulate capture module includes a second DPF module, the second DPF module is coated with an SCR catalyst, and the second SCR module and the SCR catalyst on the second DPF module are used to perform two catalytic reductions on nitrogen oxides in the exhaust gas.

[0014] In a possible implementation, the amount of the SCR catalyst coated on the second DPF module is negatively correlated with the size of the second SCR module.

[0015] In a possible implementation, the second reduction catalytic module further includes a second ASC module, and the second ASC module is located downstream of the second SCR module and is used to capture residual ammonia substances in the second SCR module.

[0016] In a possible implementation manner, the second DPF module is further coated with an ASC catalyst, and the amount of the ASC catalyst coated on the second DPF module is negatively correlated with the size of the second ASC module.

[0017] In a possible implementation, the oxidation catalytic trap module includes a first DPF module, and a DOC catalyst is coated on the first DPF module.

[0018] In one possible embodiment, the first reduction catalytic module includes a first SCR module and a first ASC module located downstream of the first SCR module, the first SCR module is used for the first catalytic reduction of nitrogen oxides in the exhaust gas with the assistance of the ammonia substance, and the first ASC module is used for the first capture of residual ammonia substances.

[0019] In a possible implementation, the first reduction catalyst module includes a first SCR module and a first ASC module that are integrated together.

[0020] In a third aspect, an embodiment of the present application provides a vehicle, comprising the above-mentioned dual-injection SCR after-treatment system.

[0021] The present application provides a dual-injection SCR post-treatment system, including a second reduction catalytic module located downstream of a second ammonia injection module, and a second particle capture module located downstream of the second reduction catalytic module. After the vehicle exhaust passes through the upstream first ammonia injection module, the first reduction catalytic module, the oxidation catalytic capture module and the second ammonia injection module to preliminarily collect and process the nitrogen oxides and large particles in the exhaust gas, the large particles in the exhaust gas are collected again by the second reduction catalytic module and the second particle capture module at the downstream end, so as to avoid the situation in the existing solution that the large-diameter particles generated when the rear-stage SCR injects urea cannot be captured, resulting in the emission of large-diameter particles in the vehicle exhaust exceeding the safety standard. Therefore, the present application reduces the pollutants emitted by vehicle exhaust and further meets the requirements of environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] Figure 1 A schematic diagram of an existing dual-injection SCR post-treatment system provided for this application;

[0024] Figure 2 Schematic diagram of the dual-injection SCR after-treatment system provided for this application Figure 1 ;

[0025] Figure 3 Schematic diagram of the dual-injection SCR after-treatment system provided for this application Figure 2 ;

[0026] Figure 4 The overall schematic diagram of the dual-injection SCR post-treatment system provided in this application Figure 3 .

[0027] Reference numerals:

[0028] 1-first ammonia injection module;

[0029] 2-first reduction catalyst module; 201-first SCR module; 202-first ASC module;

[0030] 3-oxidation catalytic capture module; 301-first DPF module;

[0031] 4-second ammonia injection module;

[0032] 5-second reduction catalytic module; 501-second SCR module; 502-second ASC module;

[0033] 6-second particle trap module; 601-second DPF module;

[0034] 7-temperature sensor; 8-flow sensor; 9-nitrogen oxide measuring device; 10-control unit.

[0035] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0036] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0037] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards, and corresponding operation entrances shall be provided for users to choose to authorize or refuse.

[0038] It should be noted that in the embodiments of the present application, certain software, components, models and other existing solutions in the industry may be mentioned, and they should be regarded as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of the present application, but it does not mean that the applicant has or will necessarily use the solution.

[0039] The dual-injection SCR (Selective Catalytic Reduction) post-treatment solution is the main treatment solution for vehicle exhaust. Figure 1 It is a schematic diagram of the existing dual-injection SCR post-treatment system. Figure 1 As shown in the figure, the dual-injection SCR post-treatment solution includes the front-stage SCR + DOC (Diesel Oxidation Catalyst) + DPF (Diesel Particulate Filter) + rear-stage SCR, so that the vehicle exhaust gas can meet the environmental protection requirements for nitrogen oxides such as , and (particles with a diameter greater than 10nm) emission requirements.

[0040] In the dual-injection SCR system, the front-stage SCR can treat part of the engine exhaust. , thus reducing the pressure on the downstream SCR; however, in order to ensure the passive regeneration capability of the post-treatment system DPF, the urea injection of the front-stage SCR will be appropriately reduced when the exhaust temperature is high. At this time, the rear-stage SCR needs to inject sufficient or even excessive urea to improve the efficiency of nitrogen and oxygen removal. However, excessive urea injection will increase the number of particles with a diameter greater than 10nm in the exhaust gas, greatly increasing the risk of excessive large particle emissions.

[0041] In the prior art, in order to avoid a large number of large particles exceeding the standard in the exhaust gas, the existing post-treatment solutions for reducing the particulate matter in the engine exhaust gas include: improving the capture capacity of the DPF by optimizing the DPF carrier structure, coating the catalyst, etc.; accurately controlling the injection amount of the post-stage SCR urea, thereby reducing the increase of particulate matter caused by urea overspray. For the optimization of the DPF carrier structure, such as increasing or reducing the length and diameter of the DPF carrier to improve the collection efficiency; for the solution of accurately controlling the injection amount of the post-stage SCR urea, the urea injection control scheme is preset based on the analysis of different environmental conditions.

[0042] An analysis of the working process of the existing technology shows that for the DPF carrier structure optimization solution, since the urea injection of the post-stage SCR is located downstream of the DPF, it is impossible to capture and control the particulate matter increased by the urea injected by the post-stage SCR; for the solution of accurately controlling the injection amount of the post-stage SCR urea, facing the complex and changeable exhaust environment and the continuously deteriorating catalyst state, it is still impossible to guarantee that there will be no urea overspray during the entire life cycle of the vehicle. Therefore, it is also impossible to effectively ensure that the emission of large particulate matter meets the standards under all operating conditions.

[0043] In view of this, the present application provides a dual-injection SCR post-treatment system, including a second reduction catalytic module located downstream of the second ammonia injection module, and a second particle capture module located downstream of the second reduction catalytic module. After the vehicle exhaust passes through the upstream first ammonia injection module, the first reduction catalytic module, the oxidation catalytic capture module and the second ammonia injection module to preliminarily collect and process the nitrogen oxides and large particles in the exhaust gas, the large particles in the exhaust gas are collected again by the second reduction catalytic module and the second particle capture module at the downstream end, so as to avoid the situation in the existing solution where the large-diameter particles generated when the rear-stage SCR injects urea cannot be captured, resulting in the emission of large-diameter particles in the vehicle exhaust exceeding the safety standard. Therefore, the present application reduces the pollutants emitted by vehicle exhaust and further meets the requirements of environmental protection.

[0044] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0045] Figure 2 Schematic diagram of the dual-injection SCR after-treatment system provided for this application Figure 1 ,like Figure 2 As shown, the dual-injection SCR post-treatment system includes: a first ammonia injection module 1, a first reduction catalyst module 2, an oxidation catalyst capture module 3, a second ammonia injection module 4, a second reduction catalyst module 5 and a second particle capture module 6.

[0046] Among them, the first ammonia injection module 1 is located downstream of the exhaust gas outlet of the engine. After the exhaust gas discharged from the vehicle engine enters the dual-injection SCR after-treatment system, the urea solution is firstly sprayed on the exhaust gas through the first ammonia injection module 1, so that the urea is decomposed at high temperature to generate ammonia, that is, the first ammonia substance is injected into the exhaust gas discharged from the exhaust gas outlet through the first ammonia injection module 1.

[0047] The first reduction catalytic module 2 is located downstream of the first ammonia injection module 1, so that when the mixture of exhaust gas and ammonia substance passes through the first reduction catalytic module 2, ammonia is used as a reducing agent to initially reduce the ammonia in the exhaust gas under the action of the SCR catalyst in the first reduction catalytic module 2. The nitrogen oxides in the exhaust gas are reduced to harmless nitrogen and water vapor, that is, the first reduction catalyst module 2 catalytically reduces the nitrogen oxides in the exhaust gas with the assistance of ammonia. , and capture residual ammonia substances.

[0048] The oxidation catalytic capture module 3 is located downstream of the first reduction catalytic module 2. After the exhaust gas is post-treated by the first reduction catalytic module 2, when it passes through the catalytic action of the oxidation catalytic capture module 3, the carbon monoxide, hydrocarbons, nitrogen monoxide in the exhaust gas and the soluble organic components in the particulate matter and oxygen are converted into water and carbon dioxide under the catalytic action of precious metals.

[0049] The DOC catalyst in the oxidation catalytic capture module 3 is usually made of porous activated alumina. The heat released by the oxidation reaction can increase the temperature of the downstream equipment and promote the start-up and regeneration of the DPF (diesel particulate filter) in the oxidation catalytic capture module 3, that is, to achieve the first capture and oxidation of particulate matter in the exhaust gas.

[0050] The second ammonia injection module 4 is located downstream of the oxidation catalytic capture module 3, so that after the exhaust gas is initially treated by the first ammonia injection module 1, the first reduction catalytic module 2 and the oxidation catalytic capture module 3, the urea solution is again injected into the treated exhaust gas through the second ammonia injection module 4, that is, a second ammonia injection is performed into the exhaust gas to further treat the nitrogen oxides in the exhaust gas.

[0051] The second reduction catalytic module 5 is located downstream of the second ammonia injection module 4, so that when the mixture of exhaust gas and ammonia substance passes through the second reduction catalytic module 5, the ammonia substance injected by the second ammonia injection module 4 is used as a reducing agent, and the nitrogen oxides in the exhaust gas are further reduced to nitrogen and water vapor under the action of the SCR catalyst in the second reduction catalytic module 5, that is, the nitrogen oxides in the exhaust gas are catalytically reduced for the second time with the assistance of the ammonia substance.

[0052] The second particulate capture module 6 is located downstream of the second reduction catalytic module 5. After the exhaust gas is processed by the second reduction catalytic module 5, the DPF in the second particulate capture module 6 captures and oxidizes the particulate matter and residual urea in the exhaust gas at this time, and assists in reducing the remaining nitrogen oxides, that is, achieving the second capture and oxidation of particulate matter in the exhaust gas.

[0053] The embodiment of the present application provides a dual-injection SCR post-treatment system, including a second reduction catalytic module 5 located downstream of the second ammonia injection module 4, and a second particle capture module 6 located downstream of the second reduction catalytic module 5. After the vehicle exhaust passes through the upstream first ammonia injection module 1, the first reduction catalytic module 2, the oxidation catalytic capture module 3 and the second ammonia injection module 4 to preliminarily collect and process the nitrogen oxides and large particles in the exhaust gas, the large particles in the exhaust gas are collected again by the second reduction catalytic module 5 and the second particle capture module 6 at the downstream end, so as to avoid the situation in the existing solution where the large-diameter particles generated when the rear-stage SCR injects urea cannot be captured, resulting in the emission of large-diameter particles in the vehicle exhaust exceeding the safety standard. Therefore, the present application reduces the pollutants emitted by vehicle exhaust and further meets the environmental protection requirements.

[0054] Figure 3 Schematic diagram of the dual-injection SCR after-treatment system provided for this application Figure 2 ,like Figure 3 As shown, in this embodiment Figure 2 Based on the embodiment, the dual-injection SCR after-treatment system is described in detail. The first reduction catalytic module 2 in the dual-injection SCR after-treatment system includes a first SCR module 201 and a first ASC module 202 located downstream of the first SCR module 201 .

[0055] Specifically, after the vehicle exhaust gas is injected with urea through the first ammonia injection module 1, the mixed gas of ammonia substance and exhaust gas after the decomposition of urea is reacted with ammonia and nitrogen oxides in the exhaust gas through the SCR catalyst of the first SCR module 201 in the first reduction catalytic module 2, so as to achieve the first catalytic reduction of nitrogen oxides in the exhaust gas, wherein the SCR catalyst is usually made of materials such as precious metals, alkali metal oxides or zeolites.

[0056] Furthermore, after the vehicle exhaust passes through the first SCR module 201 for the first catalytic reduction of nitrogen oxides, the vehicle exhaust passes through the first ASC (Ammonia slip catalyst) module 202 to process ammonia generated by the decomposition of urea to achieve the first capture of residual ammonia substances.

[0057] Furthermore, the first SCR module 201 and the first ASC module 202 in the first reduction catalytic module 2 can be integrated on the same structural carrier to save the space used by the dual-injection SCR after-treatment system.

[0058] The oxidation catalytic trap module 3 in the dual-injection SCR post-treatment system includes a first DPF module 301, on which a DOC catalyst is coated. After the vehicle exhaust gas passes through the first SCR module 201 to preliminarily treat the nitrogen oxides in the exhaust gas, and the first ASC module 202 captures the ammonia substances in the exhaust gas, when the vehicle exhaust gas passes through the first DPF module 301 in the oxidation catalytic trap module 3, the DOC catalyst coated on the first DPF module 301 converts the harmful substances in the exhaust gas into harmless substances, and at the same time, the diesel particulate trap of the first DPF module 301 realizes the first capture of large particles, so that the first DPF module 301 has both diesel oxidation catalytic function and particulate trapping function.

[0059] Specifically, pollutants such as carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides can be oxidized into carbon dioxide, water and nitrogen dioxide by the DOC catalyst coated on the first DPF module 301, wherein the DOC catalyst generally uses precious metals such as platinum (Pt), palladium (Pd) and rhodium (Rh) as active components. When the oxidation catalytic reaction is realized by the DOC catalyst coated on the first DPF module 301, the temperature is increased to provide heat for the regeneration of the diesel particulate filter of the first DPF module 301.

[0060] Furthermore, of course, the first DPF module 301 can also be divided into two independent modules such as a first oxidation catalytic module and a first particle trap module, so that the first oxidation catalytic module realizes the oxidation catalytic function, and the first particle trap module realizes the capture and oxidation function of large-diameter particles. Among them, the first oxidation catalytic module is located downstream of the first reduction catalytic module, and is used to oxidize carbon monoxide, hydrocarbons, and nitrogen monoxide in the exhaust gas; the first particle trap module is located downstream of the first oxidation catalytic module, and is used to capture and oxidize large-diameter particles in the exhaust gas for the first time.

[0061] After the initial treatment of the exhaust gas, the urea solution is injected again into the treated exhaust gas through the second ammonia injection module 4, that is, the ammonia substance is injected again into the exhaust gas after the initial treatment, so as to further treat the nitrogen oxides in the exhaust gas.

[0062] The second reduction catalytic module 5 in the dual-injection SCR post-treatment system includes a second SCR module 501,

[0063] and a second ASC module 502 , wherein the second ASC module is located downstream of the second SCR module and is used to capture residual ammonia substances after the exhaust gas passes through the second SCR module.

[0064] Furthermore, after the exhaust gas is sprayed with ammonia by the second ammonia injection module 4, the exhaust gas and ammonia after the initial treatment are passed through the second SCR module 501 in the second reduction catalytic module 5. Under the action of the SCR catalyst in the second SCR module 501, ammonia and nitrogen oxides in the exhaust gas undergo a reduction reaction again to achieve a second catalytic reduction of nitrogen oxides in the exhaust gas.

[0065] Furthermore, after the vehicle exhaust gas passes through the second SCR module 501 for the second catalytic reduction of nitrogen oxides, the vehicle exhaust gas passes through the second ASC module 502 to again process ammonia generated by the decomposition of urea, so as to achieve a second capture of residual ammonia substances in the exhaust gas.

[0066] The second particulate collection module 6 in the dual-injection SCR after-treatment system includes a second DPF module 601, wherein the second DPF module 601 is coated with an SCR catalyst, and the amount of the SCR catalyst coated on the second DPF module 601 is negatively correlated with the size of the second SCR module 501. The SCR catalyst on the second SCR module 501 and the second DPF module 601 is used for performing two catalytic reductions of nitrogen oxides in the exhaust gas.

[0067] Furthermore, after the exhaust gas passes through the second SCR module 501 and the second ASC module 502 and the nitrogen oxides in the exhaust gas are further processed, in order to avoid excessive injection of urea by the second ammonia injection module 4 to react with the nitrogen oxides in the exhaust gas to generate too many large-diameter particulate matter, under the action of the SCR catalyst coated on the second DPF module 601, the excess ammonia is again reduced with the nitrogen oxides in the exhaust gas to achieve the third catalytic reduction of the nitrogen oxides in the exhaust gas, and the large particulate matter generated during the second reduction process is captured by the diesel particulate filter of the second DPF module 601 in the second particle capture module 6, thereby reducing the emission of large-diameter particulate matter in the vehicle exhaust gas exceeding the safety standard, further meeting the environmental protection requirements.

[0068] By coating the SCR catalyst on the diesel particulate filter of the second DPF module 601, the second DPF module 601 can provide a part of the nitrogen oxide oxidation function to share a part of the nitrogen oxide oxidation function of the front-stage SCR, so the size of the front-stage SCR can be reduced, that is, the amount of SCR catalyst coated on the second DPF module 601 is negatively correlated with the size of the second SCR module 501. Of course, an ASC catalyst can also be coated on the diesel particulate filter of the second DPF module 601 to capture residual ammonia substances in the exhaust gas.

[0069] The embodiment of the present application provides a dual-injection SCR post-treatment system, including a second reduction catalytic module 5 located downstream of the second ammonia injection module 4, and a second particle capture module 6 located downstream of the second reduction catalytic module 5. After the vehicle exhaust passes through the upstream first ammonia injection module 1, the first reduction catalytic module 2, the oxidation catalytic capture module 3 and the second ammonia injection module 4 to preliminarily collect and process the nitrogen oxides and large particles in the exhaust gas, the large particles in the exhaust gas are collected again by the second reduction catalytic module 5 and the second particle capture module 6 at the downstream end, so as to avoid the situation in the existing solution where the large-diameter particles generated when the rear-stage SCR injects urea cannot be captured, resulting in the emission of large-diameter particles in the vehicle exhaust exceeding the safety standard. Therefore, the present application reduces the pollutants emitted by vehicle exhaust and further meets the environmental protection requirements.

[0070] Figure 4 The overall schematic diagram of the dual-injection SCR post-treatment system provided in this application Figure 3 ,like Figure 4 As shown, in this embodiment Figure 3 Based on the embodiment, the dual-injection SCR post-treatment system is described in detail. The dual-injection SCR post-treatment system also includes: a temperature sensor 7 , a flow sensor 8 , a nitrogen oxide measuring device 9 , and a control unit 10 .

[0071] Among them, the temperature sensor 7, the flow sensor 8 and the nitrogen oxide measuring device 9 are arranged at the inlet of the first ammonia injection module 1, the temperature sensor 7 is used to measure the exhaust gas temperature transmitted to the first ammonia injection module 1, the flow sensor 8 is used to measure the exhaust gas flow transmitted to the first ammonia injection module 1, and the nitrogen oxide measuring device 9 is used to measure the nitrogen oxide concentration in the exhaust gas transmitted to the first ammonia injection module 1.

[0072] The temperature sensor 7, the flow sensor 8, the nitrogen oxide measuring device 9, and the first ammonia injection module 1 are all communicatively connected to a control unit 10, and the control unit 10 is used to determine the amount of ammonia injected according to the exhaust gas temperature, the exhaust gas flow rate, and the nitrogen oxide concentration.

[0073] Furthermore, when the engine is running, the exhaust gas status information discharged by the engine is detected and obtained through the temperature sensor 7, the flow sensor 8 and the nitrogen oxide measuring device 9, wherein the exhaust gas status information includes the temperature, flow rate and composition of the exhaust gas per unit time, and the exhaust gas status information is sent to the control unit 10, so that the control unit 10 controls the first ammonia injection module 1 and the second ammonia injection module 4 to inject a quantitative amount of urea into the exhaust gas according to the exhaust gas status information, reduces the nitrogen oxides in the exhaust gas through the first SCR module 201 in the first reduction catalyst module 2, and oxidizes the involved urea through the first ASC module 202 in the first reduction catalyst module 2.

[0074] Furthermore, the urea injection amount, i.e., the ammonia mass, of the first ammonia injection module 1 and the second ammonia injection module 4 is calculated and obtained according to the exhaust gas temperature, flow rate, nitrogen oxide concentration and the front-stage SCR function allocation ratio, wherein the urea injection amount is positively correlated with the exhaust gas temperature, nitrogen oxide concentration and the front-stage SCR function allocation ratio.

[0075] Furthermore, the function allocation ratio of the front-stage SCR, i.e., the first SCR module 201, is 10%-100%, and the function allocation ratio of the front-stage SCR is used to indicate the percentage of nitrogen oxides allocated to the front-stage SCR for conversion to the original nitrogen oxides; the function allocation ratio of the rear-stage SCR, i.e., the second SCR module 501, is defined as 1 minus the function allocation ratio of the front-stage SCR; wherein, the allocation ratio of the front and rear stages is determined by the control strategy.

[0076] A dual-injection SCR after-treatment system provided in an embodiment of the present application realizes secondary capture of particulate matter emitted by the engine and particulate matter newly generated by the second ammonia injection module 4 by means of a second particulate capture module 6 arranged at the very end of the after-treatment system; at the same time, in order to avoid the added second particulate capture module 6 increasing the overall volume of the after-treatment system and affecting the spatial layout of the after-treatment system on the whole vehicle, the functions of selective catalytic reduction and ammonia capture are integrated by coating the particulate capture with an SCR catalyst or an ASC catalyst, thereby ensuring that the emissions of nitrogen oxides and particulate matter meet the standards without increasing the volume and cost of the existing after-treatment system and further reducing the pollutants emitted by vehicle exhaust.

[0077] An embodiment of the present application also provides a vehicle, comprising the above-mentioned dual-injection SCR after-treatment system.

[0078] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A dual-injection SCR post-treatment system, characterized in that: include: A first ammonia injection module is located downstream of the exhaust outlet of the engine and is used to perform a first ammonia injection into the exhaust gas discharged from the exhaust outlet; A first reduction catalytic module, located downstream of the first ammonia injection module, is used for first catalytically reducing nitrogen oxides in the exhaust gas with the assistance of the ammonia substance and capturing residual ammonia substances; An oxidation catalytic capture module, located downstream of the first reduction catalytic module, is used to oxidize carbon monoxide, hydrocarbons, and nitrogen monoxide in the exhaust gas, and to capture and oxidize particulate matter in the exhaust gas for the first time; A second ammonia injection module, located downstream of the oxidation catalytic capture module, is used to inject ammonia material into the tail gas for the second time; A second reduction catalytic module, located downstream of the second ammonia injection module, is used for performing a second catalytic reduction of nitrogen oxides in the exhaust gas with the assistance of the ammonia substance; The second particle trap module is located downstream of the second reduction catalytic module and is used for a second capture and oxidation of particulate matter in the exhaust gas.

2. The system according to claim 1, characterized in that The second reduction catalytic module includes a second SCR module, the second particulate trap module includes a second DPF module, the second DPF module is coated with an SCR catalyst, and the second SCR module and the SCR catalyst on the second DPF module are used to perform two catalytic reductions on nitrogen oxides in the exhaust gas.

3. The system according to claim 2, characterized in that The amount of SCR catalyst coated on the second DPF module is negatively correlated with the size of the second SCR module.

4. The system according to claim 2, characterized in that The second reduction catalyst module further includes a second ASC module, which is located downstream of the second SCR module and is used to capture residual ammonia substances in the second SCR module.

5. The system according to claim 4, characterized in that The second DPF module is also coated with an ASC catalyst, and the amount of the ASC catalyst coated on the second DPF module is negatively correlated with the size of the second ASC module.

6. The system according to any one of claims 1 to 5, characterized in that The oxidation catalytic trap module includes a first DPF module on which a DOC catalyst is coated.

7. The system according to any one of claims 1 to 5, characterized in that The first reduction catalytic module includes a first SCR module and a first ASC module located downstream of the first SCR module, the first SCR module is used for first catalytic reduction of nitrogen oxides in the exhaust gas with the assistance of the ammonia substance, and the first ASC module is used for first capturing residual ammonia substances.

8. The system according to any one of claims 1 to 5, characterized in that The first reduction catalyst module includes a first SCR module and a first ASC module integrated together.

9. A vehicle, characterized in that: include: The dual-injection SCR after-treatment system according to any one of claims 1 to 8.

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