An aftertreatment device, method, and system for a vehicle and a lean-burn gasoline engine

Abstract

The application discloses a kind of vehicle and the aftertreatment device, method and system of lean gasoline engine, device includes the first end of particle trap and exhaust manifold are connected, second end is respectively connected with the first end of control valve and bypass valve;The second end of control valve is connected with the first end of lean NOx trap, the second end of lean NOx trap is connected with the first end of three-way catalytic converter;The second end of bypass valve is connected with the first end of three-way catalytic converter;The control end of control valve and bypass valve is electrically connected with control unit;When equivalent ratio condition is determined, control bypass valve opens, control valve closes;When lean burn condition is determined, control bypass valve closes, control valve opens;When regeneration condition is determined, control bypass valve and control valve are opened, and water jet is controlled by water jet device.The technical scheme provided by the application can realize the collaborative regeneration of particle trap and lean NOx trap by water jet device to generate water gas reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of exhaust aftertreatment of lean burn of gasoline engine, and in particular to an aftertreatment device, method and system of vehicle and lean burn gasoline engine. BACKGROUND

[0002] Lean burn technology is considered as one of the important technical routes for future development of gasoline engine due to its advantages of high fuel economy, high thermal efficiency and low conventional emissions. However, due to the use of mixture deviating from the theoretical air-fuel ratio, the traditional three-way catalytic converter appears oxygen inhibition phenomenon, and the conversion rate of nitrogen oxides in the exhaust of lean burn engine decreases sharply, so that the control of NOx emission becomes a limiting factor for the development of lean burn gasoline engine technology.

[0003] Currently, the conversion efficiency of NOx in the aftertreatment system of lean burn gasoline engine needs to be further improved to control NOx emission. In view of the above problems, the existing technology mostly cancels the three-way catalytic converter (TWC), and selects to use an additional NOx catalyst, mainly including the following:

[0004] 1. Setting a NOx trap. Compared with TWC, it can chemically store NOx in the exhaust of lean burn engine in the form of nitrate or nitrite in alkali earth compounds to achieve NOx emission control. However, the NOx trap has an upper limit of storage capacity, at which time the combustion system needs to switch to rich combustion to realize the regeneration of the NOx trap (i.e. forced conversion under rich working condition is needed), which requires a high engine control system and causes local over-concentration in the cylinder, affecting the engine combustion efficiency, so this scheme is not conducive to the engine thermal efficiency and control system design.

[0005] 2. Setting a selective catalytic reduction device. By introducing an additional reducing agent, NOx is converted into ammonia and water in the form of chemical reaction to achieve NOx emission control. However, the selective catalytic reduction device needs to be regularly refilled with reducing agent, and the reducing agent injection system control is complex. At the same time, it has a large system volume and high requirements for vehicle layout. SUMMARY

[0006] The embodiment of the present application provides an aftertreatment device, method and system of vehicle and lean burn gasoline engine, which realizes the cooperative regeneration of the particulate trap and the lean burn nitrogen oxide trap by water gas reaction of water sprayed by a water sprayer, and solves the problems of forced conversion under rich working condition, large system volume and difficult control of the existing lean burn gasoline engine aftertreatment system.

[0007] In a first aspect, the embodiment of the present application provides an aftertreatment device of lean burn gasoline engine, which comprises:

[0008] The control unit, the water sprayer, the particulate trap, the lean NOx trap, the three-way catalytic converter, the control valve and the bypass valve; the first end of the particulate trap is connected with the exhaust manifold of the lean-burn gasoline engine; the water sprayer is arranged on the exhaust manifold; the second end of the particulate trap is connected with the first end of the control valve and the first end of the bypass valve respectively; the second end of the control valve is connected with the first end of the lean NOx trap, and the second end of the lean NOx trap is connected with the first end of the three-way catalytic converter; the second end of the bypass valve is connected with the first end of the three-way catalytic converter;

[0009] The control end of the control valve and the control end of the bypass valve are electrically connected with the control unit;

[0010] The particulate trap comprises a water-gas reaction catalyst;

[0011] The control unit is used for: when it is determined that the working condition of the lean-burn gasoline engine is the equivalence ratio working condition, the bypass valve is opened, and the control valve is closed; when it is determined that the working condition of the lean-burn gasoline engine is the lean-burn working condition, the bypass valve is controlled to be closed, and the control valve is controlled to be opened; when it is determined that the working condition of the lean-burn gasoline engine is the regeneration working condition, the bypass valve and the control valve are both controlled to be opened, and the water sprayer is controlled to start spraying water; wherein, under the regeneration working condition, the temperatures at the first end and the second end of the particulate trap are both greater than a preset temperature threshold.

[0012] In a second aspect, an embodiment of the present application provides a lean-burn gasoline engine system, comprising a lean-burn gasoline engine and a lean-burn gasoline engine aftertreatment device provided by any of the embodiments of the present application.

[0013] In a third aspect, an embodiment of the present application provides a vehicle, comprising a lean-burn gasoline engine system provided by the embodiments of the present application.

[0014] In a fourth aspect, an embodiment of the present application provides a lean-burn gasoline engine aftertreatment method, a lean-burn gasoline engine aftertreatment device comprising: a control unit, a water sprayer, a particulate trap, a lean NOx trap, a three-way catalytic converter, a control valve and a bypass valve; the first end of the particulate trap is connected with the exhaust manifold of the lean-burn gasoline engine; the water sprayer is arranged on the exhaust manifold; the second end of the particulate trap is connected with the first end of the control valve and the first end of the bypass valve respectively; the second end of the control valve is connected with the first end of the lean NOx trap, and the second end of the lean NOx trap is connected with the first end of the three-way catalytic converter; the second end of the bypass valve is connected with the first end of the three-way catalytic converter;

[0015] The control end of the control valve and the control end of the bypass valve are electrically connected with the control unit;

[0016] The particulate trap comprises a water-gas reaction catalyst;

[0017] The lean-burn gasoline engine aftertreatment method comprises:

[0018] The control unit controls the bypass valve to open and the control valve to close when determining that the working condition of the lean-burn gasoline engine is the equivalence ratio working condition, controls the bypass valve to close and the control valve to open when determining that the working condition of the lean-burn gasoline engine is the lean-burn working condition, and controls the bypass valve and the control valve to both open and controls the water injector to start spraying water when determining that the working condition of the lean-burn gasoline engine is the regeneration working condition, wherein the temperatures at the first end and the second end of the particulate filter are both greater than a preset temperature threshold in the regeneration working condition.

[0019] The aftertreatment device of the lean-burn gasoline engine provided by the embodiment of the present application can better capture the emissions in the exhaust gas in the equivalence ratio working condition and the lean-burn working condition, and in the regeneration working condition, the water sprayed by the water injector is evaporated and reacts with the carbon particles of the particulate filter under the action of the catalyst to consume the carbon particles, and the H2 and CO generated by the water-gas reaction enter the lean-burn nitrogen oxide trap and react with the previously captured NOx under the catalyst to consume the NOx, so that the particulate filter and the lean-burn nitrogen oxide trap achieve cooperative regeneration, without the need to adjust the engine to rich combustion and without the need to additionally add a reducing agent injection system, thus solving the problems of forced conversion in the enrichment working condition, large system volume and difficult control of the existing lean-burn gasoline engine aftertreatment system. It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] Figure 1 is a structural schematic diagram of an aftertreatment device of a lean-burn gasoline engine provided by an embodiment of the present application;

[0022] Figure 2 is a structural schematic diagram of another aftertreatment device of a lean-burn gasoline engine provided by an embodiment of the present application;

[0023] Figure 3 is a flowchart of an aftertreatment method of a lean-burn gasoline engine provided by an embodiment of the present application. DETAILED DESCRIPTION

[0024] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the accompanying drawings in the embodiments of the present application, so that those skilled in the art can better understand the technical solutions of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application.

[0025] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] Figure 1 is a structural schematic diagram of an aftertreatment device of a lean-burn gasoline engine provided by an embodiment of the present application, referring to Figure 1The device comprises a control unit 180, a water injector 150, a particulate trap 120, a lean NOx trap 130, a three-way catalytic converter 140, a control valve 160 and a bypass valve 170. The first end of the particulate trap 120 is connected to the exhaust manifold 110 of the lean-burn gasoline engine 100. The water injector 150 is arranged on the exhaust manifold 110. The second end of the particulate trap 120 is connected to the first end of the control valve 160 and the first end of the bypass valve 170 respectively. The second end of the control valve 160 is connected to the first end of the lean NOx trap 130, the second end of the lean NOx trap 130 is connected to the first end of the three-way catalytic converter 140, and the second end of the bypass valve 170 is connected to the first end of the three-way catalytic converter 140. The control end of the control valve 160 and the control end of the bypass valve 170 are electrically connected to the control unit 180. The particulate trap 120 comprises a water-gas reaction catalyst. When it is determined that the working condition of the lean-burn gasoline engine 100 is the stoichiometric condition, the control unit 180 controls the bypass valve 170 to open and controls the control valve 160 to close. When it is determined that the working condition of the lean-burn gasoline engine 100 is the lean-burn condition, the control unit 180 controls the bypass valve 170 to close and controls the control valve 160 to open. When it is determined that the working condition of the lean-burn gasoline engine 100 is the regeneration condition, the control unit 180 controls the bypass valve 170 and the control valve 160 to open and controls the water injector 150 to start injecting water, wherein the temperature at the first end and the second end of the particulate trap 120 is greater than a preset temperature threshold in the regeneration condition.

[0027] The control unit 180 can be understood as a unit that makes judgments according to the obtained instructions and sends control signals to the corresponding components. The particulate trap 120 is a device for trapping particulate matter in the exhaust gas of the lean-burn gasoline engine 100. The particulate trap 120 traps particulate matter by physical filtration and periodically regenerates to maintain its stable operation. The particulate trap 120 traps PM, PN and carbon particles in the exhaust gas of the lean-burn gasoline engine 100. The lean NOx trap 130 is used to trap nitrogen oxides in the exhaust gas of the lean-burn gasoline engine 100. The three-way catalytic converter 140 is used to treat carbon monoxide, nitrogen oxides and hydrocarbons in the exhaust gas of the lean-burn gasoline engine 100. The control valve 160 and the bypass valve 170 are devices for controlling the flow and on-off of gas. The preset temperature threshold is the minimum temperature value at which the water-gas reaction can occur.

[0028] The engine burns oil-gas mixture with lambda = 1 under the stoichiometric condition. The engine burns oil-gas mixture with lambda > 1 under the lean-burn condition. The engine burns oil-gas mixture with lambda > 1 under the regeneration condition, and at least one of the following conditions is met: the concentration of NOx in the exhaust gas exceeds a threshold concentration, the pressure difference detected between the two ends of the particulate filter 120 exceeds a pressure difference threshold, the temperature of the exhaust gas exceeds a threshold temperature, and the lean-burn gasoline engine 100 is in one of the power point conditions. When lambda = 1, the weight ratio of oil to gas in the oil-gas mixture burned by the lean-burn gasoline engine 100 is 1:14.7.

[0029] Specifically, after the exhaust gas emitted by the lean-burn gasoline engine 100 enters the aftertreatment device, the control unit 180 determines the working condition of the lean-burn gasoline engine 100 according to the concentration ratio of oil and gas in the exhaust gas. When the control unit 180 determines that the working condition of the lean-burn gasoline engine 100 is the stoichiometric condition, the control unit 180 controls the bypass valve 170 to open and the control valve 160 to close, and the exhaust gas enters the particulate filter 120 and the three-way catalytic converter 140. The aftertreatment path is the particulate filter 4 and the three-way catalytic converter 6, the particulate filter 4 treats carbon particles in the exhaust gas, and the three-way catalytic converter 6 treats CO, HC and NOx in the exhaust gas.

[0030] When the control unit 180 determines that the working condition of the lean-burn gasoline engine 100 is the lean-burn condition, the control unit 180 controls the bypass valve 170 to close and the control valve 160 to open, and the exhaust gas enters the particulate filter 120, the lean-burn nitrogen oxide trap 130 and the three-way catalytic converter 140. The aftertreatment path is the particulate filter 4, the lean-burn nitrogen oxide trap 5 and the three-way catalytic converter 6, the particulate filter 4 treats carbon particles in the exhaust gas, the lean-burn nitrogen oxide trap 5 treats NOx in the exhaust gas, and the three-way catalytic converter 6 treats CO and HC in the exhaust gas.

[0031] When the control unit 180 determines that the working condition of the lean-burn gasoline engine 100 is the regeneration condition, the control unit 180 controls the bypass valve 170 to be fully closed and the control valve 160 to be fully opened, and the water sprayer 150 starts to spray water. After the sprayed water evaporates, it enters the particulate filter 120 and reacts with the carbon particles in the particulate filter 120 under the action of the catalyst to consume the carbon particles. Since the temperatures at the first end and the second end of the particulate filter are both greater than the preset temperature threshold, the H2 and CO produced by the water-gas reaction will not be oxidized on a large scale by O2, and will immediately enter the lean-burn nitrogen oxide trap 5 to react with the previously trapped NOx under the action of the catalyst to consume the NOx. The particulate filter 4 and the lean-burn nitrogen oxide trap 5 achieve cooperative regeneration, and then enter the three-way catalytic converter 6 to treat the still unreacted CO, HC and NOx.

[0032] The aftertreatment device of the lean-burn gasoline engine 100 provided by the embodiment of the present application can better capture the emissions in the exhaust gas under the equivalent ratio working condition and the lean-burn working condition, and under the regeneration working condition, the water sprayed out by the water sprayer 150 is evaporated and reacts with the carbon particles of the particulate trap 120 under the action of the catalyst to consume the carbon particles, the H2 and CO generated by the water-gas reaction enter the lean-burn nitrogen oxide trap 5, and react with the previously captured NOx under the catalyst to consume the NOx, the particulate trap 4 and the lean-burn nitrogen oxide trap 5 realize the cooperative regeneration, the engine does not need to be adjusted to the rich state, and a reducing agent injection system does not need to be additionally arranged, and the problems of the forced conversion under the enrichment working condition, the large system volume and the difficult control of the existing aftertreatment system of the lean-burn gasoline engine are solved.

[0033] Continuing to refer to Figure 1 On the basis of the above embodiments, optionally, the water-gas reaction catalyst comprises a Fe-based catalyst, the catalyst in the lean-burn nitrogen oxide trap 130 adopts a Pt catalyst, and the catalyst of the three-way catalytic converter 140 adopts a Pt noble metal catalyst.

[0034] In the embodiment, the Fe-based catalyst is used in the water-gas reaction to accelerate the water-gas reaction between the water vapor and the carbon particles, which is beneficial to improve the consumption rate of the carbon particles. The catalyst in the lean-burn nitrogen oxide trap 130 adopts the Pt catalyst to accelerate the chemical reaction between the NOx and the H2 and CO generated by the water-gas reaction, which improves the regeneration efficiency of the lean-burn nitrogen oxide trap 130. The catalyst of the three-way catalytic converter 140 adopts the Pt noble metal catalyst to accelerate the reaction rate of the CO, the NOx and the HC.

[0035] Figure 2 is another structure schematic diagram of the aftertreatment device of the lean-burn gasoline engine 100 provided by the embodiment of the present application, referring to Figure 2Optionally, the device further comprises an electric heater 200, a temperature sensor 220, a pressure difference sensor 210 and a NOx concentration sensor 230, the first end of the electric heater 200 is connected with the exhaust manifold 110 of the lean-burn gasoline engine 100, the second end of the electric heater 200 is coupled with the first end of the particulate filter 120; the temperature sensor 220 is arranged on the pipeline connected with the second end of the particulate filter 120, the NOx concentration sensor 230 is arranged on the pipeline between the first end of the three-way catalytic converter 140 and the lean-burn NOx trap 130, the pressure difference sensor 210 is used to detect the pressure difference between the two ends of the particulate filter 120, the temperature sensor 220 is used to detect the temperature at the second end of the particulate filter 120, the NOx concentration sensor 230 is used to detect the NOx concentration, and the control unit 180 is used to obtain the pressure difference, the temperature, the NOx concentration and the oil-gas ratio of the oil-gas mixture burned by the lean-burn gasoline engine 100. When the oil-gas ratio is greater than the preset ratio, and at least one of the following conditions is met: the pressure difference is greater than the pressure difference threshold, the NOx concentration is greater than the concentration threshold, and the lean-burn gasoline engine 100 is in the power point working condition, it is judged whether the temperature is greater than the preset temperature threshold. If not, the electric heater 200 is controlled to start heating, and after the temperature is greater than the preset temperature threshold, it is determined that the lean-burn gasoline engine 100 enters the regeneration working condition, and the electric heater 200 is controlled to be closed.

[0036] In the power point working condition, the exhaust gas temperature of the lean-burn gasoline engine is high, so that the temperature of the exhaust gas in the aftertreatment device can easily reach the temperature threshold, and therefore regeneration can be performed when the power point working condition is reached. The preset ratio is a parameter ratio set by the user according to complete combustion of oil and gas. In an example, the preset ratio in the present application is 1:14.7. When the pressure difference reaches the pressure difference threshold, it indicates that the carbon particle concentration in the particulate filter 120 is high, and regeneration is needed. When the NOx concentration reaches the concentration threshold, it indicates that the NOx concentration is high, and the aftertreatment device needs to be regenerated. In addition, the temperature threshold, the pressure difference threshold and the concentration threshold are self-defined variables, which can be determined through experiments.

[0037] Specifically, when the control unit 180 judges that the oil-gas ratio in the oil-gas mixture is greater than the preset ratio, the pressure difference sensor 210 transmits the detected pressure difference to the control unit 180 in the form of an electric signal, the NOx concentration sensor 230 transmits the detected NOx concentration to the control unit 180 in the form of an electric signal, and the temperature sensor 220 transmits the temperature to the control unit 180 in the form of an electric signal.

[0038] When the control unit 180 determines that the pressure difference is greater than the pressure difference threshold, the NOx concentration is greater than the concentration threshold, and at least one of the working conditions of the lean-burn gasoline engine 100 is the power point working condition, the control unit 180 determines whether the electric heater 200 is heated according to the acquired temperature and the preset temperature threshold. If the temperature is not greater than the preset temperature threshold, the control unit 180 controls the electric heater 200 to start heating until the temperature is greater than the preset temperature threshold, and then the control unit controls the electric heater 200 to be turned off.

[0039] In the embodiment, by arranging the electric heater 200, the temperature sensor 220, the pressure difference sensor 210, and the NOx concentration sensor 230 in the lean-burn gasoline engine 100 aftertreatment device, the control unit 180 can accurately determine whether the aftertreatment device needs to be regenerated, and can accurately control the temperature of the gas in the aftertreatment device. The synergistic regeneration of the particulate trap 4 and the lean-burn nitrogen oxide trap 5 is realized through the water-coal reaction.

[0040] With reference back to Figure 2 On the basis of the above embodiments, optionally, the control unit 180 is further configured to determine that the lean-burn gasoline engine 100 is in the stoichiometric ratio working condition when the oil-gas ratio is equal to the preset ratio, and determine that the lean-burn gasoline engine 100 is in the lean-burn working condition when the oil-gas ratio is greater than the preset ratio, and the pressure difference is less than or equal to the pressure difference threshold, the NOx concentration is less than or equal to the concentration threshold, and the lean-burn gasoline engine 100 is not in the power point working condition.

[0041] In the embodiment, the control unit 180 determines the lean-burn gasoline engine 100 to be in the stoichiometric ratio working condition or the lean-burn working condition by the oil-gas ratio, the pressure difference, the temperature, the NOx concentration, and the power point working condition, thereby improving the accurate determination of the working condition of the lean-burn gasoline engine 100 by the control unit 180.

[0042] With reference back to Figure 2 On the basis of the above embodiments, optionally, the particulate trap 120 is connected to the control valve 160 and the bypass valve 170 through a pipeline, the bypass valve 170 is connected to the three-way catalytic converter 140 through a pipeline, the control valve 160 is connected to the lean-burn nitrogen oxide trap 130 through a pipeline, and the lean-burn nitrogen oxide trap 130 is connected to the three-way catalytic converter 140 through a pipeline. The pipelines are adiabatic pipelines.

[0043] In the embodiment, the particle trap 120 is connected to the control valve 160 and the bypass valve 170 by an adiabatic pipeline, the bypass valve 170 is connected to the three-way catalytic converter 140 by an adiabatic pipeline, the control valve 160 is connected to the lean NOx trap 130 by an adiabatic pipeline, and the lean NOx trap 130 is connected to the three-way catalytic converter 140 by an adiabatic pipeline, so that the temperature of the oil-gas mixture is prevented from being reduced during the transmission process. The embodiment of the present application provides a lean gasoline engine system, which comprises a lean gasoline engine 100 and the aftertreatment device of the lean gasoline engine provided by any of the embodiments of the present application.

[0044] Specifically, in the lean gasoline engine system, the lean gasoline engine 100 is connected to the aftertreatment device of the lean gasoline engine through the exhaust manifold 110.

[0045] The embodiment of the present application provides a vehicle, which comprises the lean gasoline engine system provided by the embodiment of the present application.

[0046] The embodiment of the present application provides an aftertreatment method of a lean gasoline engine, which refers to Figure 2 The aftertreatment device of the lean gasoline engine comprises a control unit 180, a water injector 150, a particle trap 120, a lean NOx trap 130, a three-way catalytic converter 140, a control valve 160 and a bypass valve 170. The first end of the particle trap 120 is connected to the exhaust manifold 110 of the gasoline engine. The water injector 150 is arranged on the exhaust manifold 110. The second end of the particle trap 120 is connected to the first end of the control valve 160 and the first end of the bypass valve 170, respectively. The second end of the control valve 160 is connected to the first end of the lean NOx trap 130, and the second end of the lean NOx trap 130 is connected to the first end of the three-way catalytic converter 140. The second end of the bypass valve 170 is connected to the first end of the three-way catalytic converter 140. The control end of the electric heater 200, the control end of the control valve 160 and the control end of the bypass valve 170 are electrically connected to the control unit 180. The particle trap 120 comprises a water-gas reaction catalyst.

[0047] The aftertreatment method of the lean gasoline engine comprises:

[0048] When it is determined that the working condition of the lean gasoline engine 100 is the equivalence ratio working condition, the control unit 180 controls the bypass valve 170 to be opened and controls the control valve 160 to be closed. When it is determined that the working condition of the lean gasoline engine 100 is the lean combustion working condition, the control unit 180 controls the bypass valve 170 to be closed and controls the control valve 160 to be opened. When it is determined that the working condition of the lean gasoline engine 100 is the regeneration working condition, the control unit 180 controls the bypass valve 170 and the control valve 160 to be opened and controls the water injector 150 to start spraying water, wherein the temperatures at the first end and the second end of the particle trap 120 are both greater than a preset temperature threshold in the regeneration working condition.

[0049] On the basis of the above embodiments, the aftertreatment device of the lean-burn gasoline engine optionally comprises: further comprising: an electric heater 200, a temperature sensor 220, a pressure difference sensor 210 and a NOx concentration sensor 230. The first end of the electric heater 200 is connected with the exhaust manifold 110 of the lean-burn gasoline engine 100, and the second end of the electric heater 200 is coupled with the first end of the particulate trap 120. The temperature sensor 220 is arranged on the pipeline connected with the second end of the particulate trap 120. The NOx concentration sensor 230 is arranged on the pipeline between the first end of the three-way catalytic converter 140 and the lean-burn NOx trap 130. The pressure difference sensor 210 is used to detect the pressure difference between the two ends of the particulate trap 120. The temperature sensor 220 is used to detect the temperature at the second end of the particulate trap 120. The NOx concentration sensor 230 is used to detect the NOx concentration.

[0050] The aftertreatment method further comprises: the control unit 180 acquires the pressure difference, the temperature, the NOx concentration and the oil-gas ratio of the oil-gas mixture combusted by the lean-burn gasoline engine 100. When the oil-gas ratio is greater than the preset ratio, and at least one of the following conditions is met: the pressure difference is greater than the pressure difference threshold, the NOx concentration is greater than the concentration threshold, and the lean-burn gasoline engine 100 is in the power point operating condition, the control unit 180 determines whether the temperature is greater than the preset temperature threshold. If not, the control unit 180 controls the electric heater 200 to start heating until the temperature is greater than the preset temperature threshold, and then determines that the lean-burn gasoline engine 100 enters the regeneration operating condition, and controls the electric heater 200 to be closed.

[0051] Continuing to refer to Figure 2 On the basis of the above embodiments, the control unit 180 determines that the lean-burn gasoline engine 100 is in the stoichiometric operating condition when the oil-gas ratio is equal to the preset ratio. When the oil-gas ratio is greater than the preset ratio, and the following conditions are met: the pressure difference is less than or equal to the pressure difference threshold, the NOx concentration is less than or equal to the concentration threshold, and the gasoline engine is not in the power point operating condition, the control unit 180 determines that the lean-burn gasoline engine 100 is in the lean-burn operating condition.

[0052] Figure 3 is a flow chart of another aftertreatment method of a lean-burn gasoline engine provided by an embodiment of the present application. Figure 3 A specific embodiment of an aftertreatment method is shown, referring to Figure 2 and Figure 3When the lean-burn gasoline engine has been started, the exhaust gas discharged from the lean-burn gasoline engine 100 enters the aftertreatment device of the lean-burn gasoline engine, and the control unit 180 determines whether the lambda of the mixed gas used for combustion is greater than 1. If the lambda of the mixed gas used for combustion is less than or equal to 1, the control unit determines that the lean-burn gasoline engine 100 is in the stoichiometric condition, and at this time, the control unit 180 controls the bypass valve 170 to be fully opened and the control valve 160 to be fully closed. When the control unit 180 determines that the lambda of the mixed gas used for combustion is greater than 1, and the concentration of the NOx concentration sensor 230 is less than or equal to the concentration threshold value, the pressure difference of the pressure difference sensor 210 is less than or equal to the pressure difference threshold value, and the lean-burn gasoline engine 100 is not in the power point condition, the control unit 180 determines that the lean-burn gasoline engine 100 is in the lean-burn condition, and at this time, the control unit 180 controls the bypass valve 170 to be fully closed and the control valve 160 to be fully opened. When the control unit 180 determines that the lambda of the mixed gas used for combustion is greater than 1, and one of the following conditions is true: the concentration of the NOx concentration sensor 230 is greater than the concentration threshold value, the pressure difference of the pressure difference sensor 210 is greater than the pressure difference threshold value, and the lean-burn gasoline engine 100 is in the power point condition, the control unit 180 continues to determine whether the temperature of the temperature sensor 220 is greater than the preset temperature threshold value. If the temperature of the temperature sensor 220 is less than or equal to the preset temperature threshold value, the control unit 180 controls the electric heater 200 to be turned on until the temperature of the temperature sensor 220 is greater than the preset temperature threshold value. When the temperature of the temperature sensor 220 is greater than the preset temperature threshold value, the control unit 180 determines that the lean-burn gasoline engine 100 is in the regeneration condition, and at this time, the control unit 180 controls the bypass valve 170 to be fully closed, the control valve 160 to be fully opened, and the water sprayer 200 to spray water.

[0053] The lean-burn gasoline engine aftertreatment method provided by the embodiment belongs to the same inventive concept as the lean-burn gasoline engine aftertreatment device provided by any of the embodiments of the application, and has corresponding beneficial effects. The technical details of the lean-burn gasoline engine aftertreatment method provided by the embodiment are described in detail in the lean-burn gasoline engine aftertreatment device provided by any of the embodiments of the application.

[0054] The specific embodiments described above do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application are included in the protection scope of the present application.

Claims

1. An aftertreatment device for a lean-burn gasoline engine, characterized in that The device comprises a control unit, a water injector, a particulate trap, a lean NOx trap, a three-way catalytic converter, a control valve and a bypass valve; a first end of the particulate trap is connected to an exhaust manifold of the gasoline engine; the water injector is arranged on the exhaust manifold; a second end of the particulate trap is connected to a first end of the control valve and a first end of the bypass valve; a second end of the control valve is connected to a first end of the lean NOx trap, and a second end of the lean NOx trap is connected to a first end of the three-way catalytic converter; a second end of the bypass valve is connected to the first end of the three-way catalytic converter; control ends of the control valve and the bypass valve are electrically connected to the control unit; the particulate trap comprises a water-gas reaction catalyst; the control unit is configured to control the bypass valve to be opened and the control valve to be closed when it is determined that the working condition of the gasoline engine is an equivalent ratio working condition; control the bypass valve to be closed and the control valve to be opened when it is determined that the working condition of the gasoline engine is a lean combustion working condition; control the bypass valve and the control valve to be opened and control the water injector to start spraying water when it is determined that the working condition of the gasoline engine is a regeneration working condition; and the temperatures at the first end and the second end of the particulate trap are both greater than a preset temperature threshold in the regeneration working condition. Further comprising:

2. The apparatus of claim 1, wherein, an electric heater, a temperature sensor, a pressure difference sensor and a NOx concentration sensor; a first end of the electric heater is connected to the exhaust manifold of the gasoline engine, and a second end of the electric heater is coupled to the first end of the particulate trap; the temperature sensor is arranged on a pipeline connected to the second end of the particulate trap; the NOx concentration sensor is arranged on a pipeline between the first end of the three-way catalytic converter and the lean NOx trap; the pressure difference sensor is configured to detect the pressure difference between the two ends of the particulate trap; the temperature sensor is configured to detect the temperature at the second end of the particulate trap; the NOx concentration sensor is configured to detect the NOx concentration; the control unit is configured to obtain the pressure difference, the temperature, the NOx concentration and the oil-gas ratio of the oil-gas mixture combusted by the gasoline engine, and when at least one of the following conditions is met: the oil-gas ratio is greater than a preset ratio, the pressure difference is greater than a pressure difference threshold, the NOx concentration is greater than a concentration threshold and the gasoline engine is in a power point working condition, determine whether the temperature is greater than a preset temperature threshold, and if not, control the electric heater to start heating until the temperature is greater than the preset temperature threshold, and then determine that the gasoline engine enters a regeneration working condition and control the electric heater to be closed.

3. The device according to claim 2, wherein: the control unit is further configured to determine that the gasoline engine is in an equivalent ratio working condition when the oil-gas ratio is equal to the preset ratio, and determine that the gasoline engine is in a lean combustion working condition when the oil-gas ratio is greater than the preset ratio, the pressure difference is less than or equal to the pressure difference threshold, the NOx concentration is less than or equal to the concentration threshold and the gasoline engine is not in a power point working condition.

4. The device according to claim 1, wherein: the water-gas reaction catalyst comprises a Fe-based catalyst; the catalyst in the lean NOx trap is a Pt catalyst; the catalyst in the three-way catalytic converter is a Pt noble metal catalyst. ​ 5. The apparatus according to claim 1, characterized in that: the particulate trap is connected by a pipe to the control valve and the bypass valve, the bypass valve is connected by a pipe to the three-way catalytic converter, the control valve is connected by a pipe to the lean NOx trap, and the lean NOx trap is connected by a pipe to the three-way catalytic converter; the pipes are pipes that have been subjected to heat insulation treatment.

6. A lean burn gasoline engine system characterized by, The lean-burn gasoline engine and the aftertreatment device of the lean-burn gasoline engine according to any one of claims 1-5.

7. A vehicle characterized by comprising: The lean-burn gasoline engine system according to claim 6.

8. An aftertreatment method of a lean-burn gasoline engine, characterized in that: the aftertreatment device of the lean-burn gasoline engine comprises a control unit, a water injector, a particulate trap, a lean NOx trap, a three-way catalytic converter, a control valve and a bypass valve; a first end of the particulate trap is connected to an exhaust manifold of the gasoline engine; the water injector is arranged on the exhaust manifold; a second end of the particulate trap is connected to a first end of the control valve and a first end of the bypass valve respectively; a second end of the control valve is connected to a first end of the lean NOx trap, and a second end of the lean NOx trap is connected to a first end of the three-way catalytic converter; a second end of the bypass valve is connected to a first end of the three-way catalytic converter; control ends of the control valve and the bypass valve are electrically connected to the control unit; the particulate trap comprises a water-gas shift catalyst; the aftertreatment method of the lean-burn gasoline engine comprises: the control unit controls the bypass valve to be opened and the control valve to be closed when it is determined that the working condition of the gasoline engine is an equivalent ratio working condition; controls the bypass valve to be closed and the control valve to be opened when it is determined that the working condition of the gasoline engine is a lean-burn working condition; and controls the bypass valve and the control valve to be opened and the water injector to start spraying water when it is determined that the working condition of the gasoline engine is a regeneration working condition, wherein, in the regeneration working condition, the temperatures at the first end and the second end of the particulate trap are both greater than a preset temperature threshold.

9. The method according to claim 8, characterized in that: The aftertreatment device of the lean-burn gasoline engine further comprises: an electric heater, a temperature sensor, a pressure difference sensor and a NOx concentration sensor; a first end of the electric heater is connected to the exhaust manifold of the gasoline engine, and a second end of the electric heater is coupled to the first end of the particulate trap; the temperature sensor is arranged on a pipe connected to the second end of the particulate trap; the NOx concentration sensor is arranged on a pipe between the first end of the three-way catalytic converter and the lean NOx trap; the pressure difference sensor is used to detect the pressure difference between the two ends of the particulate trap; the temperature sensor is used to detect the temperature at the second end of the particulate trap; the NOx concentration sensor is used to detect the NOx concentration; the method further comprises: the control unit acquires the pressure difference, the temperature, the NOx concentration and the oil-gas ratio of the oil-gas mixture combusted by the gasoline engine. The control unit judges whether the temperature is greater than a preset temperature threshold value when the oil-gas ratio is greater than a preset ratio and at least one of the following conditions is met: the pressure difference is greater than a pressure difference threshold value, the NOx concentration is greater than a concentration threshold value, and the gasoline engine is in a power point working condition. If the temperature is not greater than the preset temperature threshold value, the control unit controls the electric heater to start heating until the temperature is greater than the preset temperature threshold value, and then determines that the gasoline engine enters a regeneration working condition and controls the electric heater to be turned off.

10. The method of claim 9, wherein, Also comprising: The control unit determines that the gasoline engine is in an equivalent ratio working condition when the oil-gas ratio is equal to the preset ratio. The control unit determines that the gasoline engine is in a lean burn working condition when the oil-gas ratio is greater than the preset ratio, and the pressure difference is less than or equal to the pressure difference threshold value, the NOx concentration is less than or equal to the concentration threshold value, and the gasoline engine is not in the power point working condition.

Images