Gasoline engine lean burn exhaust gas after-treatment system, control method and vehicle

Abstract

The disclosed embodiments provide a lean-burn gasoline engine exhaust after-treatment system, method, and vehicle. The lean-burn gasoline engine exhaust after-treatment system includes a particulate filter, a deoxidizer, and a three-way catalytic converter connected in series via a pipeline. The exhaust after-treatment system also includes a bypass line connected between the downstream of the particulate filter and the upstream of the three-way catalytic converter, the bypass line being provided with a bypass valve. The connecting line between the deoxidizer and the three-way catalytic converter is provided with a control valve, the control valve being located upstream of the junction between the bypass line and the connecting line. While maintaining engine thermal efficiency, the disclosed embodiments address the low NOx conversion efficiency of lean-burn gasoline engine after-treatment systems, as well as the high control difficulty and large system size of lean-burn gasoline engine after-treatment systems.

Description

Technical Field

[0001] The present disclosure relates to the technical field of automobile exhaust after-treatment, and in particular to an exhaust after-treatment system, a control method, and a vehicle for lean burn gasoline engines. Background Art

[0002] Under the current national strategic imperatives of achieving peak carbon emissions and achieving carbon neutrality, gasoline engine technology is rapidly developing toward energy conservation and emission reduction. Lean-burn technology, with its advantages of high fuel economy, high thermal efficiency, and low conventional emissions, is considered a key technology path for future gasoline engine development. However, due to the use of mixtures that deviate from the stoichiometric air-fuel ratio, traditional three-way catalytic converters (TWCs) experience oxygen inhibition, which dramatically reduces the conversion rate of nitrogen oxides (NOx) in lean-burn engine exhaust, resulting in high NOx emissions and environmental pollution. Controlling NOx emissions has become a limiting factor in the development of lean-burn gasoline engine technology.

[0003] To effectively control NOx emissions, most existing technologies have eliminated TWC and adopted additional NOx catalysts. There are two main approaches:

[0004] (1) Install a NOx trap. Compared to a TWC, a NOx trap can chemically store NOx in the exhaust of a lean-burn engine in alkaline earth compounds in the form of nitrates or nitrites, thereby achieving NOx emission control. However, the NOx trap has an upper limit on its storage capacity. At this time, the combustion system needs to switch to rich combustion to achieve NOx trap regeneration, which places high demands on the engine control system. At the same time, it will cause local over-enrichment in the cylinder, affecting the engine combustion efficiency. Therefore, this solution is not conducive to the engine thermal efficiency and control system design.

[0005] (2) Installing a selective catalytic reducer. Chinese patent application number CN202211111496.0 introduces an additional reducing agent to chemically convert NOx into ammonia and water to achieve NOx emission control. However, the selective catalytic reducer requires regular refilling of the reducing agent, and the reducing agent injection system is complex to control. Furthermore, the system is large and has high requirements for vehicle layout, making this solution difficult to apply to light passenger vehicles.

[0006] As can be seen from the above, the existing lean-burn gasoline engine after-treatment system has the problem that NOx conversion efficiency, engine thermal efficiency, after-treatment system volume and after-treatment control difficulty cannot be taken into account at the same time. Summary of the Invention

[0007] The purpose of the embodiments of the present disclosure is to provide a gasoline engine lean burn exhaust after-treatment system, control method and vehicle to solve the technical problem in the prior art that NOx conversion efficiency, engine thermal efficiency, after-treatment system volume and after-treatment control difficulty cannot be taken into account simultaneously during the gasoline engine lean burn exhaust after-treatment process.

[0008] In order to solve the above technical problems, the embodiments of the present disclosure adopt the following technical solutions:

[0009] A lean-burn exhaust gas after-treatment system for a gasoline engine includes a particulate trap, a deoxidizer, and a three-way catalytic converter connected in series via a pipeline. The exhaust gas after-treatment system also includes a bypass pipeline connected between the downstream of the particulate trap and the upstream of the three-way catalytic converter, a bypass valve being provided on the bypass pipeline, and a control valve being provided on the connecting pipeline between the deoxidizer and the three-way catalytic converter, the control valve being located upstream of the connection between the bypass pipeline and the connecting pipeline.

[0010] In some embodiments, the catalyst of the three-way catalytic converter is a Pt noble metal catalyst, and / or the catalyst of the deoxidizer is a cerium-zirconium solid solution.

[0011] In some embodiments, the carbon loading of the particulate trap is greater than the oxygen loading of the deoxidizer.

[0012] In some embodiments, the exhaust gas after-treatment system further includes an electronic control unit, and the electronic control unit is connected to the bypass valve and the control valve respectively;

[0013] The exhaust gas after-treatment system further includes a NOx concentration sensor and an oxygen concentration sensor respectively connected to the electronic control unit, and the NOx concentration sensor and the oxygen concentration sensor are arranged on a pipeline close to the inlet of the three-way catalytic converter.

[0014] In some embodiments, the exhaust gas after-treatment system further includes a pressure difference sensor connected to the electronic control unit to detect the pressure difference between the air inlet and the air outlet of the particulate trap.

[0015] The present disclosure further provides a method for controlling exhaust gas aftertreatment of a lean-burn gasoline engine, which is applied to the above-mentioned exhaust gas aftertreatment system of a lean-burn gasoline engine. The method comprises:

[0016] Determining a current lean burn operating condition of the gasoline engine, wherein the operating condition includes an equivalence ratio operating condition, a lean burn operating condition, and a regeneration operating condition;

[0017] The bypass valve and the control valve are controlled according to the lean burn operating condition of the gasoline engine to control the operation of the deoxidizer and / or the three-way catalytic converter.

[0018] In some embodiments, controlling the bypass valve and the control valve according to the lean burn operating condition of the gasoline engine includes:

[0019] If the gasoline engine is in a lean burn condition, the bypass valve is controlled to open and the control valve is controlled to close.

[0020] If the gasoline engine is in a lean burn operating condition, controlling the bypass valve to open, and controlling the control valve to open;

[0021] If the gasoline engine is in a lean burn regeneration condition, the bypass valve is controlled to be closed, and the control valve is controlled to be opened.

[0022] In some embodiments, the method further comprises:

[0023] If lambda of the lean burn mixture of the gasoline engine=1, it is determined that the lean burn gasoline engine is in an equivalence ratio operating condition;

[0024] If lambda of the mixture is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter is less than a preset pressure difference threshold, it is determined that the gasoline engine is in a lean burn operating condition;

[0025] If lambda of the mixture is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter is greater than or equal to a preset pressure difference threshold, it is determined that the gasoline engine is in a lean burn regeneration condition.

[0026] In some embodiments, when the gasoline engine is in a lean burn operating state, the method further comprises: controlling the openings of the bypass valve and the control valve according to the relationship between the oxygen partial pressure and the NOx partial pressure;

[0027] If the oxygen partial pressure is greater than the NOx partial pressure, the opening of the bypass valve is controlled to increase, and the opening of the control valve is controlled to decrease;

[0028] If the oxygen partial pressure is equal to the NOx partial pressure, the opening of the bypass valve is controlled to remain unchanged, and the opening of the control valve is controlled to remain unchanged;

[0029] If the oxygen partial pressure is lower than the NOx partial pressure, the opening of the bypass valve is controlled to decrease, and the opening of the control valve is controlled to increase.

[0030] The present disclosure also provides a vehicle comprising the above-mentioned lean-burn exhaust gas after-treatment system for a gasoline engine.

[0031] The embodiments of the present disclosure provide a gasoline engine lean burn exhaust after-treatment system, control method, and vehicle. A particulate filter, a deoxidizer, and a three-way catalytic converter are connected in series via a pipeline. A bypass pipeline is provided between the downstream of the particulate filter and the upstream of the three-way catalytic converter. A bypass valve is provided on the bypass pipeline. A control valve is provided on the connecting pipeline between the deoxidizer and the three-way catalytic converter. The bypass valve and / or the control valve can be controlled to open or close according to the combustion conditions of the gasoline engine lean burn system to achieve oxygen partial pressure control before the TWC, thereby improving the conversion efficiency of the TWC and effectively reducing NOx emissions without affecting the thermal efficiency of the engine. At the same time, the particulate filter regeneration process can be coupled with the deoxidizer regeneration process to achieve coordinated operation of the two regeneration processes. In addition, the present disclosure only requires the addition of a deoxidizer (including corresponding connecting pipelines), a bypass pipeline, and corresponding control valves and bypass valves to perform different after-treatment processes. The entire system is small in size and easy to control. The present disclosure does not require the installation of a dedicated NOx filter. The gasoline engine can perform lean burn normally without affecting the combustion efficiency of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 Schematic diagram of the structure of the exhaust gas after-treatment system of the lean burn gasoline engine according to the embodiment of the present disclosure;

[0034] Figure 2 This is a flow chart of the exhaust gas after-treatment control method for a lean burn gasoline engine according to an embodiment of the present disclosure;

[0035] Figure 3 This is another flow chart of the exhaust after-treatment control method for a lean burn gasoline engine according to an embodiment of the present disclosure.

[0036] Reference numerals:

[0037] 1-Particulate filter; 2-Deoxidizer; 3-Three-way catalytic converter; 41-Bypass valve, 42-Control valve; 5-Electronic control unit; 61-NOx concentration sensor, 62-Oxygen concentration sensor, 63-Differential pressure sensor; 101-Bypass line; 102-Connecting line; 20-Gasoline engine combustion system, 201-Exhaust manifold. DETAILED DESCRIPTION

[0038] Various aspects and features of the present disclosure are described herein with reference to the accompanying drawings.

[0039] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0040] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0041] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0042] It should also be understood that although the present disclosure has been described with reference to certain specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the characteristics recited in the claims and are therefore within the scope of protection defined thereby.

[0043] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0044] Specific embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repetitive functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant detail. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but rather serve merely as a basis and representative basis for teaching those skilled in the art to variously employ the present disclosure with substantially any suitable detailed structure.

[0045] This description may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," each of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0046] Figure 1 The schematic diagram of the exhaust gas after-treatment system of the gasoline engine lean burn embodiment of the present disclosure is shown as follows: Figure 1As shown, an embodiment of the present disclosure provides a lean-burn exhaust after-treatment system for a gasoline engine, comprising a particulate filter (GPF) 1, a deoxidizer (deoxidizer carrier) 2, and a three-way catalytic converter (TWC) 3 connected in series via pipelines. The exhaust after-treatment system further comprises a bypass pipeline 101 connected between the downstream of the particulate filter 1 and the upstream of the three-way catalytic converter 3. A bypass valve 41 is provided on the bypass pipeline 101. A control valve 42 is provided on a connecting pipeline 102 between the deoxidizer 2 and the three-way catalytic converter 3. The control valve 42 is located upstream of the connection between the bypass pipeline 101 and the connecting pipeline 102.

[0047] Among them, the air inlet of the particulate filter 1 is connected to the exhaust gas outlet of the gasoline engine combustion system 20 through the exhaust manifold 201. The original exhaust gas generated by the lean combustion of the oil-gas mixture (referred to as the mixture) burned in the gasoline engine combustion system 20 enters the particulate filter 1. The particulate filter 1 is used to capture carbon soot particles (PM, PN) in the original exhaust gas. When the particulate matter in the particulate filter 1 accumulates to a certain extent, the particulate matter can be burned and regenerated to avoid the accumulation of particulate matter in the particulate filter 1.

[0048] The deoxidizer 2 is used to control the oxygen partial pressure before TWC catalysis; or for regeneration, to desorb the adsorbed oxygen. The desorbed oxygen enters the three-way catalytic converter 3 and reacts with the CO (carbon monoxide) and HC (hydrocarbon) particles generated by the regeneration of the particulate filter 1 in the three-way catalytic converter 3, thereby achieving coordinated regeneration of the particulate filter 1 and the deoxidizer 2.

[0049] The three-way catalytic converter 3 is used to process the particulate matter and harmful gases such as CO, HC and NOx (nitrogen oxides) captured by the particulate trap 1, thereby achieving exhaust gas post-treatment.

[0050] The bypass valve 41 is used to control the opening or closing of the bypass line 101 , and the control valve 42 is used to control the opening or closing of the connecting line 102 between the deoxidizer 2 and the three-way catalytic converter 3 .

[0051] In this embodiment, the bypass line 101 is connected in parallel with the connecting line 102 between the deoxidizer 2 and the three-way catalytic converter 3, and a bypass valve 41 is provided on the bypass line 101, and a control valve 42 is provided on the connecting line 102 between the deoxidizer 2 and the three-way catalytic converter 3. The bypass valve 41 and / or the control valve 42 can be controlled to be opened or closed according to the combustion conditions of the gasoline engine lean burn system 20, so that the exhaust gas discharged from the gasoline engine lean burn system can be treated in a targeted manner to meet different post-treatment requirements.

[0052] Specifically, when the gasoline engine's lean burn system 20 is operating in an equivalence ratio condition, bypass valve 41 is open and control valve 42 is closed. Exhaust gas passes through particulate trap 1 and then through bypass line 101 into three-way catalytic converter 3 for treatment, achieving CO, HC, NOx, and particulate matter emission control. At this point, deoxidizer 2 is short-circuited and inoperative.

[0053] When the gasoline engine lean burn system 20 is in a lean burn operating condition, the bypass valve 41 and the control valve 42 are both open. A portion of the exhaust gas passing through the particulate filter 1 enters the three-way catalytic converter 3 directly through the bypass line 101, while the remaining portion is processed by the deoxidizer 2 before entering the three-way catalytic converter 3. This allows the three-way catalytic converter 3 to control CO, HC, NOx, and particulate matter emissions in the exhaust gas after controlling the oxygen partial pressure using the deoxidizer 2. Controlling the oxygen partial pressure before the TWC through the deoxidizer 2 improves the TWC conversion efficiency and effectively reduces NOx emissions without affecting the engine's thermal efficiency.

[0054] When the gasoline engine lean burn system 20 is in the regeneration condition, the bypass valve 41 is closed and the control valve 42 is opened. The original exhaust gas passes through the particulate filter 1, the deoxidizer 2, and the three-way catalytic converter 3 in sequence. The particulate filter 1 is used to regenerate the carbon load, the deoxidizer 2 is used to regenerate the oxygen load, and the three-way catalytic converter 3 is used to control the emissions of CO, HC, and NOx in the regenerated exhaust gas.

[0055] The gasoline engine lean burn exhaust after-treatment system provided by the embodiment of the present disclosure connects a particulate filter 1, a deoxidizer 2, and a three-way catalytic converter 3 in series in sequence through pipelines, and provides a bypass pipeline 101 between the downstream of the particulate filter 1 and the upstream of the three-way catalytic converter 3. A bypass valve 41 is provided on the bypass pipeline 101, and a control valve 42 is provided on the connecting pipeline 102 between the deoxidizer 2 and the three-way catalytic converter 3. The bypass valve 41 and / or the control valve 42 can be controlled to be opened or closed according to the combustion conditions of the gasoline engine lean burn system 20 to achieve control of the oxygen partial pressure before the TWC, thereby improving the conversion efficiency of the TWC and effectively reducing NOx emissions without affecting the thermal efficiency of the engine. At the same time, the regeneration process of the particulate filter 1 can be coupled with the regeneration process of the deoxidizer 2 to achieve coordinated operation of the regeneration processes of the two. In this embodiment, different post-treatment processes can be implemented by simply adding a deoxidizer 2 (including corresponding connecting piping), a bypass line 101, and corresponding control valves 42 and 41. This results in a compact and easily controlled system. Furthermore, in this embodiment, a dedicated NOx trap is not required; the gasoline engine can operate normally using lean burn, without compromising engine combustion efficiency.

[0056] In summary, the embodiments of the present disclosure solve the problem of low NOx conversion efficiency of the lean-burn gasoline engine after-treatment system while ensuring the thermal efficiency of the engine. At the same time, it solves the problems of high control difficulty and large system size of the lean-burn gasoline engine (gasoline engine that performs lean combustion) after-treatment system.

[0057] Preferably, the catalyst of the three-way catalytic converter 3 is a Pt noble metal catalyst to improve the conversion efficiency of the exhaust gas.

[0058] Preferably, the catalyst of the deoxidizer 2 is a cerium-zirconium solid solution with high oxygen storage capacity, which can desorb more oxygen during regeneration to effectively treat NOx in the three-way catalytic converter 3 and improve the NOx conversion rate and conversion efficiency.

[0059] Preferably, the carbon load of the particulate trap 1 is greater than the oxygen load of the deoxidizer 2 to ensure that the deoxidizer 2 is fully regenerated.

[0060] Preferably, the pipelines in the exhaust gas after-treatment system (including the connecting pipelines of the series particulate filter 1, deoxidizer 2, three-way catalytic converter 3 and the bypass pipeline 101) are heat-insulated pipelines to avoid the exhaust temperature from dropping and affecting the catalyst efficiency.

[0061] In some embodiments, as shown in the figure, the exhaust gas after-treatment system further includes an electronic control unit 5, and the electronic control unit 5 is connected to the bypass valve 41 and the control valve 42 respectively;

[0062] The exhaust gas after-treatment system further includes a NOx concentration sensor 61 and an oxygen concentration sensor 62 respectively connected to the electronic control unit 5 . The NOx concentration sensor 61 and the oxygen concentration sensor 62 are arranged on a pipeline close to the inlet of the three-way catalytic converter 3 .

[0063] The electronic control unit 5 is electrically connected to the bypass valve 41 and the control valve 42 respectively, and can accurately control the opening or closing of the bypass valve 41 and the control valve 42 to ensure smooth conduction of each pipeline.

[0064] The NOx concentration sensor 61 and oxygen concentration sensor 62 are used to detect the NOx concentration and oxygen concentration before the TWC, respectively, so as to adjust the oxygen partial pressure according to the NOx concentration, thereby improving the NOx treatment effect and efficiency of the three-way catalytic converter 3. Specifically, when the bypass valve 41 is open and the control valve 42 is open, the deoxidizer 2, the NOx concentration sensor 61, and the oxygen concentration sensor 62 can form an oxygen concentration control module to control the oxygen partial pressure before the TWC. When the bypass valve 41 is open and the control valve 42 is closed, the NOx concentration sensor 61, the oxygen concentration sensor 62, and the three-way catalytic converter 3 can form a three-way catalytic conversion module to treat CO, HC, and NOx in the exhaust gas.

[0065] In this embodiment, the electronic control unit 5 can not only detect the NOx concentration and oxygen concentration through the NOx concentration sensor 61 and the oxygen concentration sensor 62 when the bypass valve 41 and / or the control valve 42 are opened, but also perform negative feedback control on the opening of the bypass valve 41 and / or the control valve 42 according to the NOx concentration and oxygen concentration detected by the NOx concentration sensor 61 and the oxygen concentration sensor 62, control the oxygen partial pressure in the exhaust gas, improve the conversion efficiency of the TWC, and reduce NOx emissions.

[0066] In some embodiments, as Figure 1 As shown, the exhaust gas aftertreatment system also includes a differential pressure sensor 63 connected to the electronic control unit 5 to detect the pressure difference between the air inlet and the air outlet of the particulate filter 1. The differential pressure sensor 63 can be used to determine the operating condition (combustion status) of the fuel-air mixture in the gasoline engine combustion system 20, thereby controlling the operation of the bypass valve 41 and the control valve 42.

[0067] Specifically, in this embodiment, the operating condition of the gasoline engine combustion system 20 is determined by the pressure difference detected by the pressure difference sensor 63 and the lambda (air-fuel ratio) of the mixture burned in the gasoline engine combustion system 20 .

[0068] (1) When lambda of the mixture is 1, it is determined that the gasoline engine combustion system 20 is in an equivalence ratio operating condition;

[0069] (2) When lambda of the mixed gas is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter 1 is less than the preset pressure difference threshold (P<P limit ), it is determined that the gasoline engine combustion system 20 is in a lean burn condition;

[0070] (3) When the lambda of the mixed gas is greater than 1, and the pressure difference between the inlet and outlet of the particulate filter is greater than or equal to the preset pressure difference threshold (P≥P limit ), it is determined that the gasoline engine combustion system 20 is in a regeneration condition.

[0071] Preset pressure difference threshold P limit The pressure difference between the inlet and outlet of the particulate filter 1 can be pre-set using test bench data. In the above embodiment, only one differential pressure sensor 63 is required to detect the differential pressure between the inlet and outlet of the particulate filter 1, making detection convenient, quick, and cost-effective. In other embodiments, pressure sensors can be installed on the inlet and outlet pipes of the particulate filter 1 to detect the differential pressure across the front and rear of the particulate filter 1.

[0072] It should be noted that in the exhaust gas treatment system provided by the embodiments of the present disclosure, the particulate filter 1, deoxidizer 2, three-way catalytic converter 3, bypass valve 41, control valve 42, various sensors, and corresponding connection structures can be configured according to actual circumstances and are not specifically limited by this disclosure. For example, in this embodiment, the particulate filter 1, deoxidizer 2, and three-way catalytic converter 3 are first connected in series before the bypass line 101 is installed, facilitating the centralized arrangement of the three devices. In other embodiments, the particulate filter 1 and three-way catalytic converter 3 can be connected in series first, and then the deoxidizer 2 can be arranged in the bypass line between the particulate filter 1 and the three-way catalytic converter 3. In this way, the main post-treatment equipment can be arranged within a limited length of space. The shape, volume, mesh size, pore size, porosity, etc. of the deoxidizer 2 (deoxidizer carrier) are also not specifically limited. The deoxidizer 2 can be a coupled carrier or a separated carrier, and the catalyst formulation in the deoxidizer 2 can also be selected according to actual needs. The shape and structure of the bypass valve 41, control valve 42, and various sensors are not specifically limited by this disclosure. For example, bypass valve 41 and control valve 42 may be one-way valves to prevent gas backflow. The gasoline engine may be a conventional gasoline engine or a hybrid gasoline engine. The present disclosure does not specifically limit the gasoline engine's structure and operating mode, including the number of cylinders, combustion injection method (port injection or direct injection), and ignition method (spark plug ignition or pre-chamber ignition).

[0073] Figure 2 and Figure 3 The flowchart of the exhaust gas post-treatment control method of the gasoline engine lean burn embodiment of the present disclosure is shown. Figure 2 and Figure 3 As shown, the embodiment of the present disclosure further provides a method for controlling exhaust gas aftertreatment of a lean burn gasoline engine, which is applied to the above-mentioned exhaust gas aftertreatment system of the lean burn gasoline engine, and the method includes:

[0074] S101: Determine a current lean burn operating condition of the gasoline engine, wherein the operating condition includes an equivalence ratio operating condition, a lean burn operating condition, and a regeneration operating condition;

[0075] S102: Control the bypass valve 41 and the control valve 42 according to the lean burn operating condition of the gasoline engine to control the operation of the deoxidizer 2 and / or the three-way catalytic converter 3.

[0076] Specifically, the above control method can be implemented by the electronic control unit 5 provided in the exhaust gas post-processing system. Figure 3As shown, the signal processor of the electronic control unit 5 can receive an engine start signal sent by the engine. If the signal processor receives the engine start signal, it determines that the engine has started running (the gasoline engine begins to perform lean burn). The electronic control unit 5 then detects the lean burn operating conditions of the gasoline engine and controls the opening or closing of the bypass valve 41 and the control valve 42 based on the lean burn operating conditions of the gasoline engine. If the signal processor does not receive the engine start signal, it determines that the gasoline engine is not performing lean burn and controls the exhaust after-treatment system to be in a closed state.

[0077] The embodiment of the present disclosure provides a method for controlling exhaust aftertreatment of a lean-burn gasoline engine. A particulate filter 1, a deoxidizer 2, and a three-way catalytic converter 3 are sequentially connected in series via pipelines. A bypass pipeline 101 is provided between the downstream of the particulate filter 1 and the upstream of the three-way catalytic converter 3. A bypass valve 41 is provided on the bypass pipeline 101. A control valve 42 is provided on a connecting pipeline 102 between the deoxidizer 2 and the three-way catalytic converter 3 to form an exhaust aftertreatment system. By controlling the opening or closing of the bypass valve 41 and / or the control valve 42 according to the operating conditions of the lean-burn gasoline engine, the oxygen partial pressure before the TWC can be controlled, thereby improving the conversion efficiency of the TWC and effectively reducing NOx emissions without affecting the thermal efficiency of the engine. At the same time, the regeneration process of the particulate filter 1 can be coupled with the regeneration process of the deoxidizer 2 to achieve coordinated operation of the two regeneration processes, and the control is precise and convenient.

[0078] In some embodiments, as Figure 3 As shown, in step S102, the bypass valve and the control valve are controlled according to the lean burn working condition of the gasoline engine, including:

[0079] S1021: If the gasoline engine is in a lean burn equivalence ratio operating condition, control the bypass valve 41 to open and control the control valve 42 to close;

[0080] S1022: If the gasoline engine is in a lean burn operating condition, control the bypass valve 41 to open, and control the control valve 42 to open;

[0081] S1023: If the gasoline engine is in a lean burn regeneration state, the bypass valve 41 is controlled to be closed, and the control valve 42 is controlled to be opened.

[0082] In steps S1021 to S1023, the bypass valve 41 and / or the control valve 42 are controlled to be opened or closed according to the lean burn operating condition of the gasoline engine, thereby controlling the operation of the particulate filter 1, the deoxidizer 2, and the three-way catalytic converter 3 to perform corresponding treatment on the original exhaust gas generated by the combustion of the mixture in the gasoline engine combustion system 20.

[0083] When the gasoline engine operates in a lean-burn equivalence ratio condition, bypass valve 41 is controlled to open and control valve 42 is controlled to close, controlling the normal operation of particulate filter 1 and three-way catalytic converter 3. Exhaust gas passes through particulate filter 1 and enters three-way catalytic converter 3 through bypass line 101 for treatment, achieving CO, HC, NOx, and particulate matter emission control. At this time, deoxidizer 2 is short-circuited and deoxidizer 2 is controlled to be inoperative.

[0084] When the gasoline engine lean burn system 20 is in a lean burn operating condition, the bypass valve 41 and the control valve 42 are both controlled to open, and the particulate filter 1, the deoxidizer 2, and the three-way catalytic converter 3 are controlled to start operating normally. After the original exhaust gas passes through the particulate filter 1, a portion of the exhaust gas directly enters the three-way catalytic converter 3 through the bypass line 101, and the other portion of the exhaust gas is treated by the deoxidizer 2 before entering the three-way catalytic converter 3. Therefore, after the oxygen partial pressure is controlled by the deoxidizer 2, the CO, HC, NOx, and particulate matter emissions in the exhaust gas are controlled through the three-way catalytic converter 3. By controlling the oxygen partial pressure before the TWC through the deoxidizer 2, the conversion efficiency of the TWC can be improved, effectively reducing NOx emissions, without affecting the thermal efficiency of the engine.

[0085] When the gasoline engine lean burn system 20 is in the regeneration condition, the bypass valve 41 is controlled to be closed, and the control valve 42 is controlled to be opened, and the particulate filter 1, the deoxidizer 2, and the three-way catalytic converter 3 are controlled to start working normally. The original exhaust gas passes through the particulate filter 1, the deoxidizer 2, and the three-way catalytic converter 3 in sequence. The particulate filter 1 is used to regenerate the carbon load, the deoxidizer 2 is used to regenerate the oxygen load, and the three-way catalytic converter 3 is used to control the CO, HC, and NOx emissions in the regenerated exhaust gas, thereby realizing the coordinated regeneration of the particulate filter 1 and the deoxidizer 2.

[0086] In some embodiments, as Figure 3 As shown, the method further includes:

[0087] S201: If lambda of the mixture in the exhaust gas of the lean burn gasoline engine is 1, it is determined that the lean burn gasoline engine is in an equivalence ratio operating condition;

[0088] S202: If lambda of the mixed gas is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter 1 is less than a preset pressure difference threshold (P<P limit ), determining that the gasoline engine is in a lean burn operating condition;

[0089] S203: If the lambda of the mixed gas is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter 1 is greater than or equal to the preset pressure difference threshold (P≥P limit ), determine that the gasoline engine lean burn is in a regeneration condition.

[0090] In step S201 to step S203, the working condition of the lean burn gasoline engine is determined based on the lambda of the fuel mixture during the lean burn of the gasoline engine and the pressure difference between the air inlet and the air outlet of the particulate filter 1. Figure 3 As shown, after the gasoline engine starts to perform lean burn, the electronic control unit 5 first detects the lambda value of the combustion mixture. If the electronic control unit 5 detects lambda = 1, it determines that the gasoline engine is in a lean burn equivalence ratio operating condition, controls the bypass valve 41 to be fully open, and controls the control valve 42 to be closed, so that the exhaust gas passing through the particulate filter 1 can quickly flow into the three-way catalytic converter 3 through the bypass line 101 to treat the exhaust gas. If the electronic control unit 5 detects lambda>1, the electronic control unit 5 controls the pressure difference sensor 63 to start detecting the pressure difference between the air inlet and the air outlet of the particulate filter 1, and compares the pressure difference with a preset pressure difference threshold. If the pressure difference between the air inlet and the air outlet of the particulate filter 1 is less than the preset pressure difference threshold (P<P limit ), it is determined that the gasoline engine is in a lean burn condition, and the electronic control unit 5 controls the bypass valve 41 and the control valve 42 to be open. At this time, the electronic control unit 5 can control the opening of the bypass valve 41 and the control valve 42 according to the NOx concentration and oxygen concentration detected by the NOx concentration sensor 61 and the oxygen concentration sensor 62; if the pressure difference between the air inlet and the air outlet of the particulate filter 1 is greater than or equal to the preset pressure difference threshold (P≥P limit ), it is determined that the gasoline engine is in a lean burn regeneration condition, the electronic control unit 5 controls the bypass valve 41 to be closed, and the control valve 42 to be in a fully open state, so as to achieve rapid regeneration of the particulate trap 1 and the deoxidizer 2.

[0091] In some embodiments, as Figure 3 As shown, when the gasoline engine is in a lean burn operating condition, the method further includes:

[0092] S301: Controlling the openings of the bypass valve 41 and the control valve 42 according to the relationship between the oxygen partial pressure and the NOx partial pressure.

[0093] Specifically, if Figure 3As shown, in this step, when the gasoline engine is in a lean-burn condition, the electronic control unit 5 can determine the relationship between the oxygen partial pressure and the NOx partial pressure based on the NOx concentration and oxygen concentration detected by the NOx concentration sensor 61 and the oxygen concentration sensor 62, and then accurately control the opening of the bypass valve 41 and the control valve 42. If the oxygen partial pressure is greater than the NOx partial pressure, it is determined that the oxygen partial pressure needs to be reduced to improve the conversion efficiency of the three-way catalytic converter 3. At this time, the electronic control unit 5 controls the opening of the bypass valve 41 to increase and the opening of the control valve 42 to decrease, so as to reduce the flow rate of exhaust gas entering the deoxidizer 2 for deoxygenation; if the oxygen partial pressure is equal to the NOx partial pressure, the opening of the bypass valve 41 is controlled to remain unchanged, and the opening of the control valve 42 is controlled to remain unchanged, and the exhaust gas enters the bypass line 101 and the deoxidizer 2 respectively according to the original flow rate; if the oxygen partial pressure is less than the NOx partial pressure, it is determined that the oxygen partial pressure needs to be increased to improve the conversion efficiency of the three-way catalytic converter 3. At this time, the electronic control unit 5 controls the opening of the bypass valve 41 to decrease and the opening of the control valve 42 to increase, so as to allow a larger flow rate of exhaust gas to enter the deoxidizer 2 for deoxygenation and provide more oxygen.

[0094] In this embodiment, after the electronic control unit 5 controls the opening and closing state and the opening degree of the bypass valve 41 and the control valve 42 according to the working conditions of the lean burn of the gasoline engine, it can detect in real time whether the engine is working normally. If it is working normally, it continues to detect the working conditions of the lean burn of the gasoline engine, and then controls the bypass valve 41 and the control valve 42 according to steps S101 and S102. This reciprocating cycle can accurately control the operation of the exhaust after-treatment system according to the real-time changing working conditions during the lean burn of the gasoline engine, thereby improving the NOx conversion efficiency of the exhaust after-treatment system and reducing the difficulty of control while ensuring the thermal efficiency of the engine.

[0095] An embodiment of the present disclosure further provides a vehicle, comprising the exhaust gas after-treatment system for lean burn of a gasoline engine according to the above embodiment.

[0096] The vehicle provided in the embodiment of the present disclosure corresponds to the exhaust gas after-treatment system of the lean burn gasoline engine in the above embodiment. Any optional items in the embodiment of the exhaust gas after-treatment system of the lean burn gasoline engine are also applicable to the embodiment of the vehicle and will not be repeated here.

[0097] The above describes in detail multiple embodiments of the present disclosure, but the present disclosure is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications to the embodiments based on the concepts of the present disclosure, and these variations and modifications should fall within the scope of protection required by the present disclosure.

[0098] In addition, although each operation is described in a specific order, this should not be understood as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details have been included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0099] Although the subject matter has been described in language specific to structural features and / or methodological logical acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are merely example forms of implementing the claims.

Claims

1. A lean burn exhaust gas after-treatment system for a gasoline engine, characterized in that: The exhaust gas after-treatment system includes a particulate filter, a deoxidizer, and a three-way catalytic converter connected in series through pipelines. The exhaust gas after-treatment system also includes a bypass pipeline connected between the downstream of the particulate filter and the upstream of the three-way catalytic converter. A bypass valve is provided on the bypass pipeline. A control valve is provided on the connecting pipeline between the deoxidizer and the three-way catalytic converter. The control valve is located upstream of the connection between the bypass pipeline and the connecting pipeline. The bypass valve and the control valve are opened or closed according to the working conditions of the gasoline engine lean burn system, and the working conditions include an equivalence ratio condition, a lean burn condition and a regeneration condition. Among them, if the gasoline engine lean burn is in the equivalence ratio condition, the bypass valve is opened and the control valve is closed; if the gasoline engine lean burn is in the lean burn condition, the bypass valve is opened and the control valve is opened; if the gasoline engine lean burn is in the regeneration condition, the bypass valve is closed and the control valve is opened.

2. The exhaust gas after-treatment system for a lean burn gasoline engine according to claim 1, characterized in that: The catalyst of the three-way catalytic converter is a Pt noble metal catalyst, and / or the catalyst of the deoxidizer is a cerium-zirconium solid solution.

3. The exhaust gas after-treatment system for a lean burn gasoline engine according to claim 1, characterized in that: The carbon loading of the particulate trap is greater than the oxygen loading of the deoxidizer.

4. The exhaust gas after-treatment system for a lean burn gasoline engine according to claim 1, characterized in that: The exhaust gas after-treatment system further includes an electronic control unit, which is connected to the bypass valve and the control valve respectively; The exhaust gas after-treatment system further includes a NOx concentration sensor and an oxygen concentration sensor respectively connected to the electronic control unit, and the NOx concentration sensor and the oxygen concentration sensor are arranged on a pipeline close to the inlet of the three-way catalytic converter.

5. The exhaust gas after-treatment system for lean burn gasoline engine according to claim 4, characterized in that: The exhaust gas after-treatment system further includes a pressure difference sensor connected to the electronic control unit to detect the pressure difference between the air inlet and the air outlet of the particulate trap.

6. A method for controlling exhaust gas aftertreatment of a lean burn gasoline engine, applied to the exhaust gas aftertreatment system of a lean burn gasoline engine according to any one of claims 1 to 5, characterized in that: include: Determine the current lean burn operating condition of the gasoline engine; The bypass valve and the control valve are controlled according to the lean burn operating condition of the gasoline engine to control the operation of the deoxidizer and / or the three-way catalytic converter.

7. The exhaust gas post-treatment control method for a lean burn gasoline engine according to claim 6, characterized in that: The method further comprises: If lambda of the lean burn mixture of the gasoline engine=1, it is determined that the lean burn gasoline engine is in an equivalence ratio operating condition; If lambda of the mixture is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter is less than a preset pressure difference threshold, it is determined that the gasoline engine is in a lean burn operating condition; If lambda of the mixture is greater than 1, and the pressure difference between the air inlet and the air outlet of the particulate filter is greater than or equal to a preset pressure difference threshold, it is determined that the gasoline engine is in a lean burn regeneration condition.

8. The exhaust gas after-treatment control method for a lean burn gasoline engine according to claim 7, characterized in that: When the gasoline engine is in a lean burn operating state, the method further comprises: controlling the openings of the bypass valve and the control valve according to the magnitude relationship between the oxygen partial pressure and the NOx partial pressure; If the oxygen partial pressure is greater than the NOx partial pressure, the opening of the bypass valve is controlled to increase, and the opening of the control valve is controlled to decrease; If the oxygen partial pressure is equal to the NOx partial pressure, the opening of the bypass valve is controlled to remain unchanged, and the opening of the control valve is controlled to remain unchanged; If the oxygen partial pressure is lower than the NOx partial pressure, the opening of the bypass valve is controlled to decrease, and the opening of the control valve is controlled to increase.

9. A vehicle, characterized in that: The invention comprises an exhaust gas after-treatment system for lean combustion of a gasoline engine according to any one of claims 1 to 5.

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