Tail gas treatment system, tail gas treatment method and vehicle

Abstract

The invention provides a tail gas treatment system, a tail gas treatment method and a vehicle, and belongs to the technical field of vehicle parts, the tail gas treatment system comprises a lean-burn nitrogen oxide trapping device and a three-way catalytic device.One end of the lean-burn nitrogen oxide trapping device is used for being connected with a tail gas inlet pipe of the vehicle, and the other end of the lean-burn nitrogen oxide trapping device is used for being connected with a tail gas outlet pipe of the vehicle; and one end of the three-way catalytic device is connected with the other end of the lean-burn nitric oxide trapping device, and the other end of the three-way catalytic device is used for being connected with a tail gas exhaust pipe of the vehicle. The tail gas treatment system provided by the embodiment of the invention can adapt to tail gas treatment under lean-burn and rich-burn working conditions, the tail gas purification effect is guaranteed, and the operation efficiency is high.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle components, and particularly to an exhaust gas treatment system, an exhaust gas treatment method, and a vehicle. Background Art

[0002] During the driving process of a vehicle, the power is mainly provided by the engine. The engine generates energy by burning gasoline or diesel to drive the vehicle. During the operation of the engine, the combustion of gasoline or diesel produces exhaust gas, which contains gases such as nitrogen oxides, hydrocarbons, and carbon monoxide. Direct emission will cause environmental pollution, so the exhaust gas needs to be treated.

[0003] In the related art, a passive SCR (Selective Catalytic Reduction) treatment system or a multi-stage catalytic treatment system (including two three-way catalytic converters and an ammonia oxidation catalytic converter) is usually adopted. Among them, the passive SCR treatment system has poor purification effects on total hydrocarbons (THC) and carbon monoxide (CO) in the exhaust gas during rich combustion of the engine, while the multi-stage catalytic treatment system can only treat the exhaust gas emissions under stoichiometric and rich combustion conditions, and is not suitable for the treatment of exhaust gas under lean combustion conditions. Moreover, under rich combustion conditions, the reduction ability of nitrogen oxides in the exhaust gas is insufficient. Summary of the Invention

[0004] Embodiments of the present application provide an exhaust gas treatment system, an exhaust gas treatment method, and a vehicle, which can adapt to the treatment of exhaust gas under lean combustion and rich combustion conditions and ensure the purification effect of the exhaust gas.

[0005] To achieve the above object, according to the first aspect of the present application, an exhaust gas treatment system is provided, including: A lean NOx trap, one end of the lean NOx trap is used to be connected to the exhaust gas inlet pipe of the vehicle, so that the exhaust gas of the vehicle enters the lean NOx trap; A three-way catalytic device, one end of the three-way catalytic device is connected to the other end of the lean NOx trap, and the other end of the three-way catalytic device is used to be connected to the exhaust gas discharge pipe of the vehicle.

[0006] Optionally, the lean NOx trap includes an oxidation section and a trapping section connected to each other. The oxidation section is arranged close to the exhaust gas inlet pipe, and the trapping section is arranged on the side of the oxidation section away from the exhaust gas inlet pipe; The oxidation section is used to oxidize nitrogen oxides in the exhaust gas, and the trapping section is used to oxidize nitrogen oxides in the exhaust gas and adsorb nitrogen oxides in the exhaust gas.

[0007] Optionally, the oxidation section includes a nitrogen oxide oxidation catalytic material; And / or, the trapping section includes a nitrogen oxide oxidation catalytic material and a nitrogen oxide storage material.

[0008] Optionally, platinum is included in the oxidation section; and / or, platinum and a barium-based material are included in the trapping section.

[0009] Optionally, the exhaust gas treatment system further includes a gas delivery device, which is connected to the three-way catalytic device to supply oxygen-containing gas to the three-way catalytic device.

[0010] Optionally, the gas delivery device includes an air pump and a gas injection structure; The outlet end of the air pump is connected to one end of the gas injection structure, and the other end of the gas injection structure is connected to the three-way catalytic device.

[0011] Optionally, the exhaust gas treatment system further includes a sensor for detecting the oxygen concentration and / or nitrogen oxide concentration in the exhaust gas.

[0012] Optionally, the sensor includes a first oxygen sensor and a first nitrogen oxide sensor, and the first oxygen sensor and the first nitrogen oxide sensor are arranged at one end of the lean NOx trap device close to the exhaust gas inlet pipe.

[0013] Optionally, the sensor includes a second oxygen sensor and a second nitrogen oxide sensor, and the second oxygen sensor and the second nitrogen oxide sensor are arranged on the connecting pipeline between the lean NOx trap device and the three-way catalytic device.

[0014] Optionally, the exhaust gas treatment system further includes a control module; The control module is electrically connected to the gas delivery device, and the control module is used to control the opening, closing and opening degree of the gas delivery device.

[0015] Optionally, the exhaust gas treatment system further includes a bypass pipeline, one end of which is connected to the exhaust gas inlet pipe, and the other end of which is used to be connected to the three-way catalytic device.

[0016] Optionally, a control valve is arranged on the exhaust gas inlet pipe, and the control valve is suitable for controlling the on-off between the exhaust gas inlet pipe and the lean NOx trap device, and controlling the on-off between the exhaust gas inlet pipe and the bypass pipeline.

[0017] According to the second aspect of the present application, there is also provided an exhaust gas treatment method, based on the above exhaust gas treatment system, including: Controlling the engine to be in a lean burn mode, and the first exhaust gas generated by the engine enters the lean NOx trap device, so that the lean NOx trap device adsorbs and stores the nitrogen oxides in the first exhaust gas to obtain a first pretreated exhaust gas; wherein, the first pretreated exhaust gas includes total hydrocarbons and / or carbon monoxide; Transporting the first pretreated exhaust gas to the three-way catalytic device to obtain a first purified exhaust gas.

[0018] Optionally, after the pretreated tail gas is conveyed to the three-way catalytic device to obtain the purified tail gas, the method further includes: Switching the engine to the rich combustion mode, and the second tail gas generated by the engine enters the lean NOx trap to release at least part of the stored NOx in the lean NOx trap, so as to obtain the second pretreated tail gas; wherein, the second pretreated tail gas includes at least one of NOx, total hydrocarbons, and carbon monoxide; Conveying the second pretreated tail gas to the three-way catalytic device to obtain the second purified tail gas.

[0019] Optionally, conveying the second pretreated tail gas to the three-way catalytic device includes: Conveying the second pretreated tail gas to the three-way catalytic device and supplying oxygen-containing gas to the three-way catalytic device.

[0020] Optionally, measuring the maximum NOx storage capacity of the lean NOx trap; Switching the engine to the rich combustion mode includes: Obtaining the actual NOx storage amount in the lean NOx trap, and when the ratio of the actual NOx storage amount to the maximum NOx storage capacity is greater than or equal to 90% and less than 100%, switching the engine to the rich combustion mode.

[0021] According to the third aspect of the present application, there is also provided a vehicle including the above-mentioned tail gas treatment system.

[0022] The tail gas treatment system provided by the embodiments of the present application includes a lean NOx trap and a three-way catalytic device. One end of the lean NOx trap is used to connect to the tail gas inlet pipe of the vehicle so that the tail gas of the vehicle enters the lean NOx trap. One end of the three-way catalytic device is connected to the other end of the lean NOx trap, and the other end of the three-way catalytic device is used to connect to the tail gas discharge pipe of the vehicle. In the lean combustion mode, through the storage of the lean NOx trap, the remaining total hydrocarbons, carbon monoxide and other gases in the tail gas are oxidized by the three-way catalytic device, so as to obtain the purified tail gas that meets the requirements. In the rich combustion mode, the stored NOx in the lean NOx trap can be released, the lean NOx trap can be regenerated, and the purification treatment is carried out through the three-way catalytic device to obtain the purified tail gas that meets the requirements. And the regeneration time of the lean NOx trap is short, and there is no need to operate the rich combustion mode for a long time. That is, the tail gas treatment system provided by the embodiments of the present application can adapt to the tail gas treatment under lean and rich combustion conditions, ensure the purification effect of the tail gas, and has a high operating efficiency.

[0023] Other features and advantages of the present application will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0025] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0026] Figure 1 This is a schematic diagram of the structure of the exhaust gas treatment system provided in the embodiment of the present application. Figure 1 ; Figure 2 This is a schematic diagram of the structure of the exhaust gas treatment system provided in the embodiment of the present application. Figure 2 ; Figure 3 This is a schematic diagram of the structure of the exhaust gas treatment system provided in the embodiment of the present application. Figure 3 ; Figure 4 This is a schematic diagram of the structure of the exhaust gas treatment system provided in the embodiment of the present application. Figure 4 ; Figure 5 This is a schematic diagram of the structure of the exhaust gas treatment system provided in the embodiment of the present application. Figure 5 .

[0027] Description of reference numerals: 10. Exhaust gas intake pipe; 20. Lean-burn NOx trapping device; 21. Oxidation section; 22. Trapping section; 30. Three-way catalytic device; 40. Exhaust gas emission pipe; 50. Gas delivery device; 51. Air pump; 52. Gas injection structure; 60. Sensor; 61. First oxygen sensor; 62. First NOx sensor; 63. Second oxygen sensor; 64. Second NOx sensor; 70. Bypass line; 80. Control valve. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] First, see Figure 1, an embodiment of the present application provides an exhaust gas treatment system, which includes a lean NOx trap device 20 and a three-way catalytic device 30. Among them, one end of the lean NOx trap device 20 is used to connect to the exhaust gas inlet pipe 10 of the vehicle, so that the exhaust gas of the vehicle enters the lean NOx trap device 20. One end of the three-way catalytic device 30 is connected to the other end of the lean NOx trap device 20, and the other end of the three-way catalytic device 30 is used to connect to the exhaust gas discharge pipe 40 of the vehicle. In the lean burn mode, the exhaust gas of the vehicle first enters the lean NOx trap device 20 (LNT) and is stored through the lean NOx trap device 20. The remaining total hydrocarbons and carbon monoxide and other gases in the exhaust gas are oxidized through the three-way catalytic device 30, so as to obtain purified exhaust gas that meets the requirements. In the rich burn mode, the nitrogen oxides stored in the lean NOx trap device 20 can be released, the lean NOx trap device 20 can be regenerated, and the purification treatment is carried out through the three-way catalytic device 30 to obtain purified exhaust gas that meets the requirements. And the regeneration time of the lean NOx trap device 20 is short, and there is no need to operate the rich burn mode for a long time. That is, the exhaust gas treatment system provided by the embodiment of the present application can adapt to the exhaust gas treatment under lean burn and rich burn conditions, ensure the purification effect of the exhaust gas, and has a high operating efficiency.

[0030] It can be understood that the lean burn mode means that the engine operates under an air-fuel ratio greater than the theoretical air-fuel ratio. The rich burn mode means that the engine operates under an air-fuel ratio less than the theoretical air-fuel ratio. Due to incomplete combustion and a relatively low combustion temperature, the content of nitrogen oxides in the generated exhaust gas is low, but the content of total hydrocarbons and carbon monoxide is high.

[0031] The exhaust gas treatment system provided by the embodiment of the present application combines the lean NOx trap device 20 (LNT) and the three-way catalytic device 30 (TWC). In the lean burn mode, nitrogen oxides can be adsorbed by the LNT, and then the remaining total hydrocarbons and carbon monoxide are purified through the TWC at the rear end. The LNT can be regenerated in the rich burn mode, and the regeneration time is short. When the LNT reaches the maximum nitrogen oxide storage capacity, the LNT can be regenerated by operating the rich burn mode for a short time, and the regeneration exhaust gas is purified through the TWC, which can ensure the exhaust gas treatment effect under different working conditions, and at the same time can reduce the operation time of the rich burn mode and increase fuel economy.

[0032] In some embodiments, please refer to Figure 1 , the lean NOx trap device 20 includes an oxidation section 21 and a trapping section 22 that are connected to each other. The oxidation section 21 is arranged close to the exhaust gas inlet pipe 10, and the trapping section 22 is arranged on the side of the oxidation section 21 away from the exhaust gas inlet pipe 10. The oxidation section 21 is used to oxidize the nitrogen oxides in the exhaust gas, and the trapping section 22 is used to oxidize and adsorb the nitrogen oxides in the exhaust gas.

[0033] The oxidation section 21 oxidizes the nitrogen oxides in the tail gas (for example, oxidizes nitric oxide in the tail gas to nitrogen dioxide), which can improve the adsorption and storage capacity of the trapping section 22 for nitrogen oxides. The trapping section 22 can improve the oxidation effect on nitrogen oxides and ensure the storage performance of nitrogen oxides, reduce the emission of nitrogen oxides, and improve the purification effect on the tail gas.

[0034] In some embodiments, the oxidation section 21 includes a nitrogen oxide oxidation catalytic material. The carrier in the oxidation section 21 includes a nitrogen oxide oxidation catalytic material, which can oxidize the nitrogen oxides in the tail gas (for example, oxidize nitric oxide in the tail gas to nitrogen dioxide), and can improve the adsorption and storage capacity for nitrogen oxides.

[0035] In some embodiments, the trapping section 22 includes a nitrogen oxide oxidation catalytic material and a nitrogen oxide storage material. The carrier in the trapping section 22 includes a nitrogen oxide oxidation catalytic material and a nitrogen oxide storage material, which can improve the oxidation effect on nitrogen oxides and ensure the storage performance of nitrogen oxides, reduce the emission of nitrogen oxides, and improve the purification effect on the tail gas.

[0036] In some embodiments, the oxidation section 21 includes platinum. Platinum has high-efficient oxidation catalytic performance for nitrogen oxides, which can promote the reaction of nitric oxide (NO) and oxygen (O 2 ) at a relatively low temperature to generate nitrogen dioxide (NO 2 ), improve the storage efficiency of the LNT for nitrogen oxides (NO x ), and platinum has good stability.

[0037] In some embodiments, the trapping section 22 includes platinum and a barium-based material. The platinum in the trapping section 22 can provide an oxidation catalytic effect on the nitrogen oxides that are not oxidized in the oxidation section 21, fully oxidize the nitrogen oxides, and react with the nitrogen oxides through the barium-based material to store the nitrogen oxides in the trapping section 22.

[0038] Among them, the reactions that occur to nitrogen oxides in the lean NOx trap device 20 are as follows: (1) In the lean burn mode, nitrogen oxides react with oxygen under the catalysis of platinum in the oxidation section 21 and the trapping section 22, and the reaction formula is as shown in Formula I: 2NO + O 2 → 2NO 2 Formula I; (2) The generated NO 2 reacts with the barium-based material in the trapping section 22, and the reaction formulas are as shown in Formulas II-IV: BaCO 3 + NO → Ba(NO 3 ) 2+CO Formula II; BaCO 3 +NO → Ba(NO 2 ) 2 +CO 2 Formula III; Ba(NO 2 ) 2 +NO 2 → BaNO 3 Formula IV; (3)Under the rich combustion mode, the content of carbon monoxide (CO) in the exhaust gas is relatively high, which can react with BaNO 3 to release nitrogen oxides and realize the regeneration of the carrier in the LNT. The reaction formula is shown in Formula V: BaNO 3 +CO → BaCO 3 +2NO + 2CO 2 Formula V.

[0039] In some embodiments, in the lean NOx trap device 20, the ratio between the length of the oxidation section 21 and the length of the trapping section 22 does not exceed 1:3. By controlling the ratio between the length of the oxidation section 21 and the length of the trapping section 22 within this range, the oxidation effect of nitrogen oxides in the exhaust gas can be ensured, and at the same time, there can be sufficient nitrogen oxide storage material to store nitrogen oxides.

[0040] In the related art, the nitrogen oxide oxidation catalytic material (such as platinum) and the nitrogen oxide storage material (such as barium-based material) in the lean NOx trap device 20 are arranged in a mixed coating manner (equivalent to only including the trapping section 22 in the embodiments of the present application), while the lean NOx trap device 20 provided in the embodiments of the present application includes an oxidation section 21 coated separately with the nitrogen oxide oxidation catalytic material and a trapping section 22 coated simultaneously with the nitrogen oxide oxidation catalytic material and the nitrogen oxide storage material, which can improve the storage performance of nitrogen oxides.

[0041] In some embodiments, please refer to Figure 2 , the exhaust gas treatment system further includes a gas delivery device 50, and the gas delivery device 50 is connected to the three-way catalytic device 30 to supply oxygen-containing gas to the three-way catalytic device 30. During the purification process of the total hydrocarbons and carbon monoxide in the exhaust gas by the three-way catalytic device 30, oxygen is consumed to cause the total hydrocarbons and carbon monoxide to react. The gas delivery device 50 can deliver oxygen-containing gas to the three-way catalytic device 30 as needed to provide the oxygen required for the reaction, thereby improving the purification performance of the three-way catalytic device 30.

[0042] In some embodiments, please refer to Figure 2, the gas delivery device 50 includes an air pump 51 and a gas injection structure 52. The air outlet end of the air pump 51 is connected to one end of the gas injection structure 52, and the other end of the gas injection structure 52 is connected to the three-way catalytic device 30.

[0043] The air pump 51 can provide compressed oxygen-containing gas, ensuring the ability to deliver oxygen-containing gas to the three-way catalytic device 30 and reducing the risk of tail gas leakage in the tail gas treatment device. The gas injection structure 52 can ensure the accuracy of oxygen-containing gas delivery and deliver the oxygen-containing gas to the appropriate position.

[0044] In some embodiments, please refer to Figure 3 , the tail gas treatment system further includes a sensor 60 for detecting the oxygen concentration and / or nitrogen oxide concentration in the tail gas. Through the sensor 60 provided in the tail gas treatment system, parameters such as the oxygen concentration and nitrogen oxide concentration can be monitored in real time and feedback can be provided. Based on the monitoring data of the sensor 60, precise control of the tail gas treatment system can be achieved, connecting the operating state of the tail gas treatment system and ensuring the reliability of the tail gas treatment system.

[0045] In some embodiments, please refer to Figure 3 , the sensor 60 includes a first oxygen sensor 61 and a second nitrogen oxide sensor 64. The first oxygen sensor 61 and the first nitrogen oxide sensor 62 are arranged at one end of the lean NOx trap 20 close to the tail gas inlet pipe 10. By arranging the first oxygen sensor 61 and the first nitrogen oxide sensor 62 at one end of the lean NOx trap 20 close to the tail gas inlet pipe 10, the oxygen concentration and nitrogen oxide concentration of the tail gas entering the tail gas treatment system can be monitored in real time, and corresponding regulation can be carried out according to the obtained parameters, improving the accuracy of tail gas treatment.

[0046] In some embodiments, please refer to Figure 3 , the sensor 60 includes a second oxygen sensor 63 and a second nitrogen oxide sensor 64. The second oxygen sensor 63 and the second nitrogen oxide sensor 64 are arranged on the connecting pipeline between the lean NOx trap 20 and the three-way catalytic device 30. By arranging the second oxygen sensor 63 and the second nitrogen oxide sensor 64 on the connecting pipeline between the lean NOx trap 20 and the three-way catalytic device 30, the treatment state and effect of the lean NOx trap 20 can be monitored, the regeneration process can be optimized, and the three-way catalytic device 30 can be adjusted according to the monitored parameters, improving the stability of the tail gas treatment system.

[0047] In some embodiments, the exhaust gas treatment system further includes a control module (not shown in the figure). The control module is electrically connected to the gas delivery device 50, and the control module is used to control the opening, closing, and opening degree of the gas delivery device 50. By electrically connecting the control module (such as an ECU) to the gas delivery device 50, the gas delivery device 50 can be precisely controlled through the control module, thereby improving the purification effect of the exhaust gas treatment system.

[0048] In some embodiments, the control module is also electrically connected to the sensor 60. By electrically connecting the control module to the sensor 60, the parameters monitored by the sensor 60 can be obtained, and the gas delivery device 50 can be precisely controlled according to the parameters.

[0049] In some embodiments, please refer to Figure 4 and Figure 5 , the exhaust gas treatment system further includes a bypass pipeline 70. One end of the bypass pipeline 70 is connected to the exhaust gas inlet pipe 10, and the other end of the bypass pipeline 70 is connected to the three-way catalytic device 30.

[0050] By providing the bypass pipeline 70, a suitable exhaust gas treatment path can be selected according to the working condition of the engine in the vehicle. The exhaust gas can be treated through the exhaust gas inlet pipe 10 → LNT → TWC → exhaust gas discharge pipe 40, or the path of the exhaust gas inlet pipe 10 → TWC → exhaust gas discharge pipe 40 can be realized through the bypass pipeline 70, thereby increasing different treatment modes.

[0051] In some embodiments, please refer to Figure 5 , a control valve 80 is provided on the exhaust gas inlet pipe 10. The control valve 80 is adapted to control the on-off between the exhaust gas inlet pipe 10 and the lean NOx trap 20, and, control the on-off between the exhaust gas inlet pipe 10 and the bypass pipeline 70.

[0052] That is, the mode switching between "exhaust gas inlet pipe 10 → LNT → TWC → exhaust gas discharge pipe 40" and "exhaust gas inlet pipe 10 → TWC → exhaust gas discharge pipe 40" is realized through the control valve 80. For example, when the temperature of the exhaust gas is less than or equal to 600 °C, the exhaust gas inlet pipe 10 and the lean NOx trap 20 can be kept connected, and the connection relationship between the exhaust gas inlet pipe 10 and the bypass pipeline 70 can be disconnected, which can ensure the exhaust gas treatment effect; when the temperature of the exhaust gas is greater than 600 °C, the exhaust gas inlet pipe 10 and the lean NOx trap 20 can be disconnected, and the exhaust gas inlet pipe 10 and the bypass pipeline 70 can be kept connected, reducing the damage caused by the high-temperature exhaust gas to the lean NOx trap 20 and improving the service life of the lean NOx trap 20.

[0053] Second, the embodiments of the present application further provide an exhaust gas treatment method, based on the above exhaust gas treatment system, including: Control the engine to operate in a lean burn mode. The first exhaust gas generated by the engine enters the lean NOx trap 20, so that the lean NOx trap 20 adsorbs and stores the nitrogen oxides in the first exhaust gas to obtain a first pretreated exhaust gas; wherein, the first pretreated exhaust gas includes total hydrocarbons and / or carbon monoxide; Transport the first pretreated exhaust gas to the three-way catalytic device 30 to obtain a first purified exhaust gas.

[0054] That is, when the engine is in the lean burn mode, the engine generates the first exhaust gas. The first exhaust gas has a high content of nitrogen oxides, a low content of total hydrocarbons and carbon monoxide, and a high oxygen content. The lean NOx trap 20 can oxidize and store the nitrogen oxides in the first exhaust gas to obtain a first pretreated exhaust gas. The total hydrocarbons and carbon monoxide in the first pretreated exhaust gas can be purified in the three-way catalytic device 30, so as to obtain a first purified exhaust gas that meets the requirements.

[0055] In some embodiments, after transporting the pretreated exhaust gas to the three-way catalytic device 30 to obtain a purified exhaust gas, it further includes: Switch the engine to a rich burn mode. The second exhaust gas generated by the engine enters the lean NOx trap 20, so that at least part of the nitrogen oxides stored in the lean NOx trap 20 are released to obtain a second pretreated exhaust gas; wherein, the second pretreated exhaust gas includes at least one of nitrogen oxides, total hydrocarbons and carbon monoxide; Transport the second pretreated exhaust gas to the three-way catalytic device 30 to obtain a second purified exhaust gas.

[0056] As described above, the lean NOx trap 20 needs to be regenerated. By switching the engine to the rich burn mode, a second exhaust gas with a low nitrogen oxide content and a high total hydrocarbon and carbon monoxide content can be generated, which can release the nitrogen oxides stored in the lean NOx trap 20 to obtain a second pretreated exhaust gas. The second pretreated exhaust gas can be purified by the three-way catalytic device 30, so as to obtain a second purified exhaust gas that meets the requirements.

[0057] Since the rich burn regeneration time of the lean NOx trap 20 is short, the operation time of the engine in the rich burn mode can be reduced, thereby improving the combustion efficiency of the fuel, enhancing the operating stability of the engine, and ensuring the purification effect of the exhaust gas.

[0058] In some embodiments, transporting the second pretreated exhaust gas to the three-way catalytic device 30 includes: Transport the second pretreated exhaust gas to the three-way catalytic device 30 and supply an oxygen-containing gas to the three-way catalytic device 30.

[0059] The three-way catalytic device 30 includes precious metal materials such as platinum, palladium, and rhodium. Nitrogen oxides can undergo reduction reactions with reducing substances such as total hydrocarbons and carbon monoxide in the three-way catalytic device 30 to generate nitrogen, carbon dioxide, and water. Carbon monoxide can undergo an oxidation reaction with oxygen in the three-way catalytic device 30 to generate carbon dioxide. Total hydrocarbons can undergo an oxidation reaction with oxygen in the three-way catalytic device 30 to generate carbon dioxide and water. By supplying an oxygen-containing gas to the three-way catalytic device 30, the oxygen supply can be increased, thereby improving the purification effect of the three-way catalytic device 30 on the second pretreated tail gas.

[0060] It should be noted that when the engine enters the rich combustion condition, the lean NOx trap 20 regenerates and releases NOx. The control module obtains the NOx concentration data measured by the first NOx sensor 62 in real time, calculates the cumulative amount, and then adds it to the NOx content stored in the lean NOx trap 20 to obtain the total cumulative NOx content. The first oxygen sensor 61 performs negative feedback in the rich combustion mode. At the same time, the second oxygen sensor 63 measures the oxygen concentration in the tail gas after passing through the lean NOx trap 20 and feeds it back to the control module. The control module calculates the remaining amounts of total hydrocarbons and carbon monoxide remaining after purifying NOx in the three-way catalytic device 30 based on the total cumulative NOx content, the rich combustion lambda (rich combustion air-fuel ratio), and the oxygen concentration measured by the first oxygen sensor 61. Combining with the oxygen concentration measured by the second oxygen sensor 63, it controls the gas delivery device 50 to deliver the oxygen-containing gas, so that the tail gas entering the three-way catalytic device 30 reaches the equivalent ratio combustion exhaust gas emission state, and the three-way catalytic device 30 completely purifies the tail gas.

[0061] In some embodiments, the maximum NOx storage capacity of the lean NOx trap 20 is measured; Switching the engine to the rich combustion mode includes: Obtaining the actual NOx storage amount in the lean NOx trap 20. When the ratio of the actual NOx storage amount to the maximum NOx storage capacity is greater than or equal to 90% and less than 100%, the engine is switched to the rich combustion mode.

[0062] By measuring the maximum NOx storage capacity of the lean NOx trap 20, the switching timing between the lean combustion mode and the rich combustion mode can be determined, ensuring the tail gas purification treatment effect, reducing NOx leakage, and achieving precise control while improving the treatment efficiency.

[0063] Exemplarily, the method for measuring the maximum nitrogen oxide storage capacity of the lean-burn nitrogen oxide trap 20 may be as follows: In the lean-burn mode, the nitrogen oxide concentration in the first exhaust gas is measured in real time by the first nitrogen oxide sensor 62 and the cumulative amount is calculated. When the second nitrogen oxide sensor 64 monitors a change in the nitrogen oxide concentration, it indicates that the nitrogen oxides in the LNT are saturated. Record the storage amount of nitrogen oxides in the LNT at this time as the maximum nitrogen oxide storage capacity.

[0064] After the lean-burn nitrogen oxide trap 20 reaches the maximum nitrogen oxide storage capacity, it is unable to continue adsorbing nitrogen oxides in the exhaust gas, which easily leads to the escape of nitrogen oxides during the switching between the lean-burn mode and the rich-burn mode. In the embodiments of the present application, the switching from the lean-burn mode to the rich-burn mode is performed when the ratio of the actual nitrogen oxide storage amount to the maximum nitrogen oxide storage capacity is greater than or equal to 90% and less than 100%. This can not only ensure the nitrogen oxide storage capacity of the lean-burn nitrogen oxide trap 20 but also reduce the leakage and escape of nitrogen oxides during the switching between the lean-burn mode and the rich-burn mode, thus ensuring the effect of exhaust gas treatment.

[0065] According to the third aspect of the present application, a vehicle is further provided, including the above exhaust gas treatment system.

[0066] The vehicle provided by the embodiments of the present application has all the beneficial effects of the above-mentioned exhaust gas treatment system, which will not be elaborated herein.

[0067] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0068] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0069] Among the embodiments, embodiments, and related technical features of the present application, they can be combined and replaced with each other without conflict.

[0070] The above are only the preferred embodiments of the present application and do not impose any form of limitation on the present application. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A tail gas treatment system, characterized in that: include: A lean-burn nitrogen oxide trap device, one end of which is used to be connected to an exhaust gas intake pipe of a vehicle so that the exhaust gas of the vehicle enters the lean-burn nitrogen oxide trap device; A three-way catalytic device, one end of which is connected to the other end of the lean-burn nitrogen oxide trap device, and the other end of the three-way catalytic device is used to be connected to the exhaust pipe of the vehicle.

2. The exhaust gas treatment system according to claim 1, characterized in that: The lean-burn nitrogen oxide trapping device comprises an oxidation section and a trapping section connected to each other, wherein the oxidation section is arranged close to the tail gas intake pipe, and the trapping section is arranged on a side of the oxidation section away from the tail gas intake pipe; The oxidation section is used for oxidizing the nitrogen oxides in the tail gas, and the capture section is used for oxidizing the nitrogen oxides in the tail gas and adsorbing the nitrogen oxides in the tail gas.

3. The exhaust gas treatment system according to claim 2, characterized in that: The oxidation section includes a nitrogen oxide oxidation catalytic material; And / or, the trap section includes the nitrogen oxide oxidation catalytic material and the nitrogen oxide storage material.

4. The exhaust gas treatment system according to claim 3, characterized in that: The oxidation section includes platinum; And / or, the capture section includes platinum and barium based materials.

5. The exhaust gas treatment system according to claim 1, characterized in that: The exhaust gas treatment system further comprises a gas delivery device, which is connected to the three-way catalytic device to provide oxygen-containing gas to the three-way catalytic device.

6. The exhaust gas treatment system according to claim 5, characterized in that: The gas delivery device comprises an air pump and a gas injection structure; The gas outlet end of the air pump is connected to one end of the gas injection structure, and the other end of the gas injection structure is connected to the three-way catalytic device.

7. The exhaust gas treatment system according to claim 1, characterized in that: The exhaust gas treatment system further comprises a sensor, and the sensor is used to detect the oxygen concentration and / or nitrogen oxide concentration in the exhaust gas.

8. The exhaust gas treatment system according to claim 7, characterized in that: The sensor comprises a first oxygen sensor and a first nitrogen oxide sensor, and the first oxygen sensor and the first nitrogen oxide sensor are arranged at one end of the lean-burn nitrogen oxide trapping device close to the exhaust gas intake pipe.

9. The exhaust gas treatment system according to claim 7, characterized in that: The sensor comprises a second oxygen sensor and a second nitrogen oxide sensor, and the second oxygen sensor and the second nitrogen oxide sensor are arranged on a connecting pipeline between the lean-burn nitrogen oxide trap device and the three-way catalytic device.

10. The exhaust gas treatment system according to claim 5, characterized in that: The exhaust gas treatment system also includes a control module; The control module is electrically connected to the gas delivery device, and the control module is used to control the opening, closing and opening degree of the gas delivery device.

11. The tail gas treatment system according to any one of claims 1 to 10, characterized in that: The exhaust gas treatment system further comprises a bypass pipeline, one end of which is used to be connected to the exhaust gas intake pipe, and the other end of which is connected to the three-way catalytic device.

12. The exhaust gas treatment system according to claim 11, characterized in that: The exhaust gas intake pipe is provided with a control valve, and the control valve is suitable for controlling the connection and disconnection between the exhaust gas intake pipe and the lean-burn nitrogen oxide trapping device, and controlling the connection and disconnection between the exhaust gas intake pipe and the bypass line.

13. A tail gas treatment method, based on the tail gas treatment system according to any one of claims 1 to 12, characterized in that: include: Controlling the engine to be in a lean-burn mode, the first exhaust gas generated by the engine enters a lean-burn nitrogen oxide trap device, so that the lean-burn nitrogen oxide trap device adsorbs and stores nitrogen oxides in the first exhaust gas to obtain a first pre-treated exhaust gas; wherein the first pre-treated exhaust gas includes total hydrocarbons and / or carbon monoxide; The first pretreated tail gas is transported to a three-way catalytic device to obtain a first purified tail gas.

14. The tail gas treatment method according to claim 13, characterized in that: After the pre-treated tail gas is transported to the three-way catalytic device to obtain purified tail gas, the method further includes: Switching the engine to a rich combustion mode, the second exhaust gas generated by the engine enters the lean-burn nitrogen oxide trap device, so that at least part of the nitrogen oxides stored in the lean-burn nitrogen oxide trap device are released to obtain a second pre-treated exhaust gas; wherein the second pre-treated exhaust gas includes at least one of nitrogen oxides, total hydrocarbons and carbon monoxide; The second pretreated exhaust gas is transported to the three-way catalytic device to obtain a second purified exhaust gas.

15. The tail gas treatment method according to claim 14, characterized in that: The method of delivering the second pre-treated tail gas to the three-way catalytic device comprises: The second pretreated tail gas is transported to the three-way catalytic device, and oxygen-containing gas is provided to the three-way catalytic device.

16. The tail gas treatment method according to claim 13, characterized in that: measuring a maximum nitrogen oxide storage capacity of the lean nitrogen oxide trap; Switching the engine to a rich combustion mode comprises: The actual storage amount of nitrogen oxides in the lean-burn nitrogen oxide trap device is obtained, and when the ratio of the actual storage amount of nitrogen oxides to the maximum storage amount of nitrogen oxides is greater than or equal to 90% and less than 100%, the engine is switched to a rich-burn mode.

17. A vehicle, characterized in that: It comprises the exhaust gas treatment system as described in any one of claims 1 to 12.

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