CN114718711B

CN114718711B - Automobile exhaust treatment device and method

Info

Publication number: CN114718711B
Application number: CN202110012093.XA
Authority: CN
Inventors: 马俊生; 吕永; 刘炜; 苏庆鹏; 白振霄; 刘巨江
Original assignee: Guangzhou Automobile Group Co Ltd
Current assignee: Guangzhou Automobile Group Co Ltd
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2023-04-07
Anticipated expiration: 2041-01-04
Also published as: CN114718711A

Abstract

The embodiment of the invention provides a device and a method for treating automobile exhaust, wherein an electronic control unit controls a sulfur reduction catalyst to perform sulfur reduction adsorption on sulfur dioxide in the exhaust of an engine, and then the exhaust of the engine is introduced into a lean NOx trap to perform nitrogen oxide adsorption treatment, so that the exhaust of the engine entering the lean NOx trap to perform the nitrogen oxide adsorption treatment does not contain sulfur-containing compounds, and the problem that the lean NOx trap is extremely sensitive to sulfur is solved. When the NOx sensor detects that nitrogen oxide exists, the electronic control unit switches the working mode, the over-rich mixed gas in the tail gas of the engine is directly subjected to flow direction regeneration treatment on the lean NOx trap, rather than passing through the sulfur reduction catalyst first, the situation that a large amount of sulfur dioxide adsorbed in the sulfur reduction catalyst is released and then flows into the lean NOx catalyst is avoided, and the problem that in the prior art, desulfurization is difficult to achieve by part of sulfate in the lean NOx trap and the sulfur has incomplete reversible effects on the lean NOx trap is solved.

Description

Automobile exhaust treatment device and method

Technical Field

The invention relates to the technical field of tail gas treatment, in particular to a device and a method for treating automobile tail gas.

Background

With increasingly stringent passenger vehicle fuel economy standards, it becomes important to further reduce the fuel consumption of vehicles. Besides the application of vehicle electrification, how to further improve the self thermal efficiency of the engine is particularly critical. In many documents, the thermal efficiency of the current gasoline engine is reported to have room for improvement, and lean burn is one of the important ways to improve the thermal efficiency of the gasoline engine. The exhaust emission of the lean-burn engine cannot be effectively converted by the NOx emission only through the three-way catalyst, and a lean-burn NOx trap needs to be added. Compared with a three-way catalyst, the lean-burn NOx trap is more sensitive to sulfur, and the adsorbent of the lean-burn NOx trap also has strong affinity to sulfur, so that the lean-burn NOx trap is poisoned by sulfur, and the NOx conversion efficiency is greatly reduced.

The high exhaust temperature is one of the conditions of the desulfurization process, and the chinese patent publication discloses a desulfurization system and method for a Lean NOx Trap (LNT), including implementing the desulfurization process by increasing the exhaust temperature in a manner including delaying the ignition angle of the engine and injecting secondary air, which may increase the exhaust temperature but is not advantageous for the desulfurization reaction in an oxidation environment having a high oxygen concentration, which may cause problems. The chinese patent publication discloses a method and an apparatus for purifying exhaust gas having a NOx storage catalyst and a pre-catalyst, which realize desulfurization by increasing exhaust temperature and in a reducing atmosphere suitable for desorption. In practice, part of the sulfides are difficult to realize the desulfurization process, such as sulfates generated by the reaction of sulfur dioxide and engine oil combustion products, as shown in the literature, the desulfurization conditions are extremely harsh once the catalyst attached to the lean NOx trap is used, and even if part of the desulfurization is realized, the conversion efficiency can be recovered to a certain degree, but the practical test result shows that the effectiveness of the lean NOx trap is difficult to recover to the original level. I.e. sulphur is not fully reversible on lean NOx traps.

In summary, in the prior art, it is difficult to desulfate a part of sulfate in the lean NOx trap, and sulfur has an incomplete reversible effect on the lean NOx trap, resulting in a problem of reduced efficiency of the lean NOx trap.

Disclosure of Invention

In order to solve the above problems, the present invention provides a device and a method for treating automobile exhaust, which are used to solve the problems that in the prior art, desulfurization of part of sulfate in a lean NOx trap is difficult to achieve, and efficiency of the lean NOx trap is reduced due to the incomplete reversible effect of sulfur on the lean NOx trap.

In order to solve the technical problem, the embodiment of the invention adopts the following technical scheme:

the device for treating the automobile exhaust is characterized by comprising an electronic control unit, a first exhaust pipe, a second exhaust pipe, a third exhaust pipe, a fourth exhaust pipe, a sulfur reduction catalyst, a lean-burn NOx trap, a NOx sensor, a first flow dividing valve and a second flow dividing valve, wherein the first exhaust pipe, the sulfur reduction catalyst, the second exhaust pipe, the lean-burn NOx trap and the third exhaust pipe are sequentially connected, the NOx sensor is arranged on the third exhaust pipe, and one end, far away from the sulfur reduction catalyst, of the first exhaust pipe is connected with the exhaust end of an engine;

the first end of the fourth exhaust pipe is connected with the first exhaust pipe through the first flow dividing valve, and the second end of the fourth exhaust pipe is connected with the second exhaust pipe through the second flow dividing valve;

the electronic control unit is respectively and electrically connected with the first flow dividing valve, the second flow dividing valve, the NOx sensor and an oil injector on the engine and is used for controlling the tail gas treatment working mode of the automobile.

Further, the treatment device further comprises a temperature sensor, a sulfur dioxide sensor, a fifth exhaust pipe, a sixth exhaust pipe, a third diverter valve, a fourth diverter valve and a first valve, wherein the temperature sensor is arranged on the first exhaust pipe, and the sulfur dioxide sensor is arranged on the first exhaust pipe;

the first end of the fifth exhaust pipe is connected with the fourth exhaust pipe through the third flow dividing valve, and the second end of the fifth exhaust pipe is connected with the third exhaust pipe through the fourth flow dividing valve;

the first end of the sixth exhaust pipe is connected with the first exhaust pipe through the first valve, the joint of the sixth exhaust pipe and the first exhaust pipe is arranged between the joint of the fourth exhaust pipe and the first exhaust pipe and the sulfur reduction catalyst, the second end of the sixth exhaust pipe is connected with the third exhaust pipe, the joint of the sixth exhaust pipe and the third exhaust pipe is arranged on the side, away from the lean NOx trap, of the joint of the third exhaust pipe and the fifth exhaust pipe, and the NOx sensor is arranged on the side, away from the lean NOx trap, of the joint of the sixth exhaust pipe and the third exhaust pipe;

and the temperature sensor, the sulfur dioxide sensor, the third shunt valve, the fourth shunt valve and the first valve are respectively and electrically connected with the electronic control unit.

Further, the electronic control unit is electrically connected with a spark plug on the engine.

Further, the treatment device further comprises a one-way valve, and the one-way valve is arranged on the sixth exhaust pipe.

Further, the sulfur reduction catalyst includes a catalyst and an adsorbent.

Further, the adsorbent is a non-alkali metal.

Further, the processing method comprises the following steps:

the embodiment of the invention also provides a treatment method of the automobile exhaust, which comprises the following steps:

treating the tail gas of the engine through a first working mode or a second working mode to obtain a treated first tail gas;

judging whether nitrogen oxides exist in the first tail gas or not;

when the first tail gas contains nitrogen oxides, treating the tail gas of the engine through a second working die;

when no nitrogen oxide exists in the first tail gas, treating the tail gas of the engine through a first working mode;

wherein:

the first working mode comprises a first working mode in which the tail gas of the engine is sequentially subjected to sulfur reduction adsorption of a sulfur reduction catalyst and nitrogen oxide adsorption treatment of a lean NOx trap;

the second working mode comprises a second working mode for controlling the excess air coefficient in the tail gas of the engine within a preset range and carrying out regeneration treatment on the nitrogen oxide adsorbed in the lean-burn NOx trap.

Further, the step of treating the exhaust gas of the engine through the second working mold specifically includes:

acquiring the content of sulfur adsorbed in the sulfur reduction adsorption treatment of the sulfur reduction catalyst in the first working mode;

judging whether the sulfur content exceeds a preset desulfurization threshold value;

and when the sulfur content does not exceed the preset desulfurization threshold value, treating the tail gas of the engine through the working mode.

Further, the second working mode also comprises a third working mode of controlling the excess air coefficient in the tail gas of the engine within a preset range, controlling the temperature of the tail gas of the engine to be higher than a preset temperature threshold value, and performing reverse regeneration on the lean NOx trap and desulfurization regeneration on the sulfur reduction catalyst;

the method for treating the tail gas of the engine through the first working mode or the second working mode specifically comprises the following steps:

treating the tail gas of the engine through a first working mode, a second working mode or a third working mode to obtain a first treated tail gas;

the treatment of the exhaust gas of the engine through the second working mode specifically comprises:

and treating the tail gas of the engine through a second working mode or a third working mode.

Further, after the step of judging whether the sulfur content exceeds a preset desulfurization threshold value, the method further comprises the following steps:

when the sulfur content exceeds the preset desulfurization threshold value, acquiring the temperature of tail gas of the engine;

judging whether the temperature of the tail gas of the engine exceeds a preset temperature threshold value or not;

and when the temperature of the tail gas of the engine exceeds a preset temperature threshold value, treating the tail gas of the engine through the third working mode.

Further, after determining whether the temperature of the exhaust gas of the engine exceeds a preset temperature threshold, the method further includes:

and when the temperature of the tail gas of the engine does not exceed the preset temperature threshold, the ignition angle is postponed to a preset angle for ignition, and whether the temperature of the tail gas of the engine exceeds the preset temperature threshold is judged again.

Further, the value range of the preset desulfurization threshold is 75% -85% of the maximum stored sulfur content of the sulfur reduction catalyst.

Further, the excess air ratio in the exhaust gas of the engine is controlled to be less than 1 within a preset range.

Further, the excess air ratio in the exhaust gas of the engine is within a preset range of 0.9-0.99.

Further, the value range of the preset temperature threshold is 550-650 degrees.

Further, the value range of the preset angle is 1-3 degrees CA.

Compared with the prior art, the embodiment of the invention has the beneficial effects that:

the embodiment of the invention provides a device and a method for treating automobile exhaust, wherein the device comprises an electronic control unit, a first exhaust pipe, a second exhaust pipe, a third exhaust pipe, a fourth exhaust pipe, a sulfur reduction catalyst, a lean-burn NOx trap, a NOx sensor, a first flow dividing valve and a second flow dividing valve, the sulfur reduction catalyst is controlled by the electronic control unit to carry out sulfur reduction adsorption on sulfur dioxide in the exhaust of an engine, and then the exhaust of the engine is introduced into the lean-burn NOx trap to carry out nitrogen oxide adsorption treatment, so that the engine entering the lean-burn NOx trap to carry out nitrogen oxide adsorption treatment does not contain sulfur compounds, and the problems that the lean-burn NOx trap is easy to form sulfur poisoning and the NOx conversion efficiency is greatly reduced are solved;

when the NOx sensor detects that nitrogen oxide exists, the electronic control unit switches the working mode, the over-rich mixed gas in the tail gas of the engine directly flows to the lean NOx trap for regeneration treatment, and at the moment, because the excess air coefficient in the tail gas of the engine is controlled within a preset range, the nitrogen oxide in the lean NOx trap is released under the rich-combustion reducing atmosphere in the tail gas of the engine, and reacts with a reducing agent in the tail gas of the engine to generate nitrogen harmless to the environment. Due to the rich reducing atmosphere, a small amount of sulfur dioxide in the exhaust gas of the engine is not adsorbed on the surface of the lean NOx trap to cause sulfur poisoning of the lean NOx trap, but is directly discharged to the atmosphere, thereby ensuring that the lean NOx trap has no risk of sulfur poisoning. Therefore, the conversion rate of the lean NOx trap is kept in a stable and reversible state, and the problems that in the prior art, desulfurization is difficult to realize by part of sulfate in the lean NOx trap, and the efficiency of the lean NOx trap is reduced due to the influence of sulfur on the incomplete reversibility of the lean NOx trap are solved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a first operating mode of an automobile exhaust gas treatment device according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a second operation mode of the device for treating automobile exhaust according to the embodiment of the present invention;

fig. 3 is a schematic structural diagram of a third operating mode of an automobile exhaust gas treatment device according to an embodiment of the present invention;

FIG. 4 is a flow chart of a method for treating exhaust gas of an automobile according to an embodiment of the present invention;

fig. 5 is a logic block diagram of a method for treating automobile exhaust according to an embodiment of the present invention.

Wherein:

1. an engine; 2. a first exhaust pipe; 3. an electronic control unit; 4. a sulfur reduction catalyst; 5. a second exhaust pipe; 6. a lean NOx trap; 7. a third exhaust pipe; 8. a first diverter valve; 9. a front connecting part; 10. a third diverter valve; 11. a fourth exhaust pipe; 12. a second diverter valve; 13. a fifth exhaust pipe; 14. a fourth diverter valve; 15. a sixth exhaust pipe; 16. a first valve; 17. a one-way valve; 18. a temperature sensor; 19. a NOx sensor; 20. an oil injector; 21. a spark plug; 22. a sulfur dioxide sensor.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the embodiments of the present application and simplifying the description, but do not indicate or imply that the referred devices or elements must have specific orientations, be configured in specific orientations, and operate, and thus, should not be construed as limiting the embodiments of the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present application, as shown in fig. 1-3, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a fixed connection, an interchangeable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, and a communication between two elements. Specific meanings of the above terms in the embodiments of the present application can be understood in specific cases by those of ordinary skill in the art.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The embodiment of the invention provides a treatment device for automobile exhaust, which comprises an electronic control unit 3, a first exhaust pipe 2, a second exhaust pipe 5, a third exhaust pipe 7, a fourth exhaust pipe 11, a sulfur reduction catalyst 4, a lean-burn NOx trap 6, an NOx sensor 19, a first flow dividing valve 8 and a second flow dividing valve 12, wherein the first exhaust pipe 2, the sulfur reduction catalyst 4, the second exhaust pipe 5, the lean-burn NOx trap 6 and the third exhaust pipe 7 are sequentially connected, the NOx sensor 19 is arranged on the third exhaust pipe 7, and one end, far away from the sulfur reduction catalyst 4, of the first exhaust pipe 2 is connected with an engine 1;

a first end of the fourth exhaust pipe 11 is connected with the first exhaust pipe 2 through the first flow dividing valve 8, and a second end of the fourth exhaust pipe 11 is connected with the second exhaust pipe 5 through a second flow dividing valve 12;

the electronic control unit 3 is electrically connected with the first shunt valve 8, the second shunt valve 12, the NOx sensor 19 and the fuel injector 20 on the engine 1, respectively, and is used for controlling the tail gas treatment working mode of the automobile.

The electronic control unit 3 is a control unit such as a microcomputer or a single chip microcomputer, which can receive, process and control information.

The electronic control unit 3 controls the following two working modes including a first working mode and a second working mode;

the working process of the working mode I and the working mode II is as follows:

when starting, the exhaust gas of the engine 1 is treated by using the first operating mode, and in the first operating mode, the first diverter valve 8 and the second diverter valve 12 respectively close two ends of the fourth exhaust pipe 11, so that the exhaust gas of the engine 1 does not flow into the fourth exhaust pipe 11.

The operation mode of the first operation mode is as shown in fig. 1, the exhaust gas of the engine 1 is discharged from the engine 1, and flows through the first exhaust pipe 2, the sulfur reduction catalyst 4, the second exhaust pipe 5, the lean NOx trap 6 and the third exhaust pipe 7 in sequence; namely, sulfur dioxide in the tail gas of the engine 1 is firstly subjected to sulfur reduction adsorption at the sulfur reduction catalyst 4, and then residual nitrogen oxides in the tail gas of the engine 1 are subjected to adsorption treatment at the lean NOx trap 6, so that the tail gas of the engine 1 entering the lean NOx trap 6 for nitrogen oxide adsorption treatment does not contain sulfur compounds, and therefore the problem that the lean NOx trap 6 is extremely easy to form sulfur poisoning and the problem that the NOx conversion efficiency in the lean NOx trap 6 is greatly reduced is solved.

The NOx sensor 19 detects whether the exhaust gas flowing through the third exhaust pipe 7 contains nitrogen oxide, and when the nitrogen oxide is detected, the NOx sensor 19 sends a signal to the electronic control unit 3, and the electronic control unit 3 switches the working mode to process the exhaust gas of the engine 1.

The working mode of the second working mode is shown in fig. 2, the electronic control unit 3 controls the excess air factor in the tail gas of the engine 1 within a preset range through an oil injector 20 on the engine 1; the electronic control unit 3 controls the first diverter valve 8 to close a channel of the over-rich mixed gas of the tail gas of the engine 1 flowing to the direction of the sulfur reduction catalyst 4 and open a channel flowing to the fourth exhaust pipe 11; the electronic control unit 3 controls the second flow dividing valve 12 to close a channel of the tail gas of the engine 1 in the direction of the sulfur reduction catalyst 4 and open a channel passing through part of the second exhaust pipe 5 to the lean NOx trap 6;

the specific working process of the working mode II comprises the following steps: the exhaust gas of the engine 1 flows through the way that the exhaust gas discharged by the engine 1 and flowing through the first exhaust pipe 2 flows through the fourth exhaust pipe 11, the second exhaust pipe 5 and the lean NOx trap 6 in sequence through the first flow dividing valve 8 and then is discharged through the third exhaust pipe 7; because the excess air coefficient in the tail gas of the engine 1 is controlled within a preset range, the tail gas of the engine 1 is in a rich-burn reducing atmosphere, so that the nitrogen oxide adsorbed on the lean-burn NOx trap 6 is released and reacts with the reducing agent in the tail gas of the engine 1 to generate nitrogen which is harmless to the environment. Because of the rich reducing atmosphere, a small amount of sulfur dioxide in the exhaust gas of the engine 1 is not adsorbed on the surface of the lean NOx trap 6, which causes sulfur poisoning of the lean NOx trap 6, but passes through the lean NOx trap 6 and is directly discharged to the atmosphere, thereby ensuring that the lean NOx trap 6 has no risk of sulfur poisoning.

The first working mode and the second working mode are switched to ensure that the lean NOx trap 6 has no risk of sulfur poisoning, and the cycle of adsorption treatment of the lean NOx trap 6 on tail gas of the engine 1 and regeneration of the lean NOx trap 6 can be realized, so that the conversion rate of the lean NOx trap 6 is kept in a stable and reversible state, and the technical problem that the conversion efficiency is reduced after the lean NOx trap 6 adsorbs sulfur in the prior art is solved.

Wherein, in the second working mode, the second flow dividing valve 12 closes the passage of the exhaust gas of the engine 1 flowing to the direction of the sulfur reduction catalyst 4 to prevent the exhaust gas from flowing back to the sulfur reduction catalyst 4.

The treatment device further comprises a temperature sensor 18, a sulfur dioxide sensor 22, a fifth exhaust pipe 13, a sixth exhaust pipe 15, a third flow dividing valve 10, a fourth flow dividing valve 14 and a first valve 16, wherein the temperature sensor 18 is arranged on the first exhaust pipe 2, and the sulfur dioxide sensor 22 is arranged on the first exhaust pipe 2;

a first end of the fifth exhaust pipe 13 is connected with the fourth exhaust pipe 11 through the third flow dividing valve 10, and a second end of the fifth exhaust pipe 13 is connected with the third exhaust pipe 7 through the fourth flow dividing valve 14;

a first end of the sixth exhaust pipe 15 is connected to the first exhaust pipe 2 through the first valve 16, and the connection between the sixth exhaust pipe 15 and the first exhaust pipe 2 is disposed between the junction of the fourth exhaust pipe 11 and the first exhaust pipe 2 and the sulfur reduction catalyst 4, a second end of the sixth exhaust pipe 15 is connected to the third exhaust pipe 7, and the junction between the sixth exhaust pipe 15 and the third exhaust pipe 7 is disposed on a side of the junction between the third exhaust pipe 7 and the fifth exhaust pipe 13 away from the lean NOx trap 6, and the NOx sensor 19 is disposed on a side of the junction between the sixth exhaust pipe 15 and the third exhaust pipe 7 away from the lean NOx trap 6;

the temperature sensor 18, the sulfur dioxide sensor 22, the third diverter valve 10, the fourth diverter valve 14 and the first valve 16 are electrically connected with the electronic control unit 3, respectively.

The electronic control unit 3 calculates the sulfur content in the sulfur reduction catalyst 4 according to the concentration of the sulfur dioxide entering the sulfur reduction catalyst 4 detected by the sulfur dioxide sensor 22, judges whether the sulfur content exceeds a preset desulfurization threshold value or not by comparing the sulfur content with the preset desulfurization threshold value, and when the sulfur content exceeds the preset desulfurization threshold value, the electronic control unit 3 switches the working mode of the processing device to a third working mode;

in the third operating mode shown in fig. 5, the electronic control unit 3 controls the excess air ratio in the exhaust gas of the engine 1 to be within a preset range through an injector 20 on the engine 1; the electronic control unit 3 controls the first flow dividing valve 8 to close a channel of the tail gas of the engine 1 flowing to the direction of the sulfur reduction catalyst 4 and open a channel of the tail gas flowing to the fourth exhaust pipe 11; controlling the third diverter valve 10 to open a passage leading to the fifth exhaust pipe 13, and closing the passage leading to the second exhaust pipe 5 through the fourth exhaust pipe 11 by the third diverter valve 10; the fourth diverter valve 14 opens the third exhaust pipe 7 to flow to the lean NOx trap 6, the fourth diverter valve 14 closes a passage to the third exhaust pipe 7 away from the lean NOx trap 6, the second diverter valve 12 closes a passage to the fourth exhaust pipe 11, and the second diverter valve 12 opens a passage to the second exhaust pipe 5 to flow normally; the first valve 16 opens a passage to the sixth exhaust pipe 15.

The electronic control unit further comprises a third working mode:

the specific working process of the third working mode is as follows:

as shown in fig. 3, exhaust gas of the engine 1 is discharged from the engine 1, and is discharged from the third exhaust pipe 7 via a portion of the first exhaust pipe 2, a portion of the fourth exhaust pipe 11, a fifth exhaust pipe 13, a lean NOx trap 6, a second exhaust pipe 5, a sulfur reduction catalyst 4, and a sixth exhaust pipe 15, wherein a junction between the sixth exhaust pipe 15 and the third exhaust pipe 7 is disposed on a side of a junction between the third exhaust pipe 7 and the fifth exhaust pipe 13, which side is away from the lean NOx trap 6, so that the exhaust gas can be discharged via a portion of the sixth exhaust pipe 15 to the third exhaust pipe 7. The exhaust gas of the engine 1 in the third operating mode is rich-burning high-temperature exhaust gas suitable for desulfurization. If the rich-burn and high-temperature tail gas passes through the sulfur reduction catalyst 4 and the lean NOx trap 6 in sequence, sulfur dioxide fully adsorbed in the sulfur reduction catalyst 4 can be desulfurized, and then the sulfur dioxide can be released in a large amount in a short time and flows to the lean NOx trap 6, so that the risk of sulfur poisoning of the lean NOx trap 6 is increased. Therefore, in the third operating mode, the exhaust gas of the engine 1 firstly passes through the lean NOx trap 6, the nitrogen oxide adsorbed in the lean NOx trap 6 is released by the rich high-temperature exhaust gas, and the excess air factor in the exhaust gas of the engine 1 is controlled within a preset range, that is, the excess air factor reacts with the reducing agent in the high-temperature exhaust gas to generate nitrogen which is harmless to the environment. And further flows into the sulfur reduction catalyst 4, and the rich-burning high-temperature tail gas enables the sulfur dioxide fully adsorbed by the sulfur reduction catalyst 4 to be released, so that the desulfurization regeneration process of the sulfur reduction catalyst 4 is realized.

The first diverter valve 8 closes a passage of the tail gas of the engine 1 flowing to the direction of the sulfur reduction catalyst 4, so as to prevent the tail gas from flowing back to the direction of the engine 1, and the first valve 16 can also be a diverter valve, so that the passage flowing to the first exhaust pipe 2 to the direction of the engine 1 is also closed while the passage of the sixth exhaust pipe 15 is opened, and the tail gas is prevented from flowing back to the direction of the engine 1. In addition, because the first flow dividing valve 8 can prevent the exhaust gas from flowing back to the engine 1, the first valve 16 can be selected as a common valve, and is mainly used for preventing the treated exhaust gas from flowing out of the sixth exhaust pipe 15 in the first and second operation modes.

Preferably, the treatment device further comprises a one-way valve 17, said one-way valve 17 being arranged on said sixth exhaust duct 15. The problem that the tail gas discharged from the third exhaust pipe 7 flows back through the sixth exhaust pipe 15 is avoided. The connection mode can adopt a welding mode.

Wherein, fourth blast pipe 11 includes preceding connecting portion 9, the first end of preceding connecting portion 9 is connected with first blast pipe 2, and the second end of preceding connecting portion 9 is connected with fifth blast pipe 13, and preceding connecting portion 9 sets up in welding inserts fourth blast pipe 11 preceding connecting portion 9 is convenient for the installation of first branch valve 8 and third branch valve 10.

Wherein the second diverter valve 12 closes the passage leading to the fourth exhaust pipe 11, preventing the tail from flowing back into the passage of the fourth exhaust pipe 11.

The electronic control unit 3 is electrically connected with a spark plug 21 on the engine 1, and realizes that the ignition angle is retarded to the preset angle to ignite by controlling the spark plug 21 of the engine 1.

Wherein the sulfur reduction catalyst 4 comprises a catalyst and an adsorbent.

Preferably, the catalyst is preferably platinum catalyst.

Because the adsorbent of alkali metal is sensitive to sulfur and difficult to realize desulfurization regeneration, the adsorbent is preferably non-alkali metal, wherein the adsorbent can be selected from copper oxide/aluminum oxide, and the adsorbent can be effectively regenerated after sulfur adsorption.

As shown in fig. 4 and 5, the present embodiment further provides a method for treating automobile exhaust, where the method includes the following steps:

treating the tail gas of the engine 1 through a first working mode or a second working mode to obtain a treated first tail gas;

judging whether nitrogen oxides exist in the first tail gas or not;

when the first tail gas contains nitrogen oxides, treating the tail gas of the engine 1 through a second working die;

when no nitrogen oxide exists in the first exhaust gas, the exhaust gas of the engine 1 is treated through a first working mode;

wherein:

the first working mode comprises a first working mode for sequentially carrying out sulfur reduction adsorption of a sulfur reduction catalyst 4 and nitrogen oxide adsorption treatment of a lean NOx trap 6 on tail gas of the engine;

the first working mode specifically comprises the following steps: sulfur reduction adsorption is carried out on sulfur dioxide in tail gas of the engine 1, and then residual nitrogen oxides in the tail gas of the engine 1 are subjected to adsorption treatment, so that the engine 1 which enters the lean-burn NOx trap 6 and is subjected to the nitrogen oxide adsorption treatment does not contain sulfur compounds, and the problems that the lean-burn NOx trap 6 is easy to form sulfur poisoning and the NOx conversion efficiency is greatly reduced are solved.

The second operation mode includes a second operation mode in which the excess air ratio in the exhaust gas of the engine 1 is controlled within a preset range and the nitrogen oxides adsorbed in the lean NOx trap 6 are subjected to regeneration treatment.

The second working mode specifically comprises the following steps: the over-rich mixed gas in the tail gas of the engine 1 directly flows to the lean NOx trap 6, and the nitrogen oxide adsorbed in the lean NOx trap 6 is regenerated, at the moment, because the excess air coefficient in the tail gas of the engine 1 is controlled within a preset range, the nitrogen oxide adsorbed on the lean NOx trap 6 is released under the rich reducing atmosphere in the tail gas of the engine 1, and reacts with the reducing agent in the tail gas of the engine 1 to generate nitrogen which is harmless to the environment. Because the exhaust gas is rich in combustion at this time, a small amount of sulfur dioxide in the exhaust gas of the engine 1 is not adsorbed on the surface of the lean NOx trap 6 to cause sulfur poisoning of the lean NOx trap 6, but is directly discharged to the atmosphere after being adsorbed by nitrogen oxide, thereby ensuring that the lean NOx trap 6 has no risk of sulfur poisoning.

The second working mode also comprises a third working mode of controlling the excess air coefficient in the tail gas of the engine 1 within a preset range, controlling the temperature of the tail gas of the engine to be higher than a preset temperature threshold value, and performing reverse regeneration on the lean NOx trap and desulfurization regeneration on the sulfur reduction catalyst;

the third working mode is specifically as follows: because the excess air coefficient in the tail gas of the engine 1 is controlled within a preset range, the ignition angle is retarded to a preset angle for ignition, so that the temperature of the tail gas of the engine 1 is higher than a preset temperature threshold value suitable for desulfurization, namely the tail gas of the engine 1 in the third working mode is rich-burning high-temperature tail gas suitable for desulfurization.

Wherein the excess air ratio in the exhaust gas of the engine 1 is controlled to be less than 1 in a preset range, and the excess air ratio in the exhaust gas of the engine 1 is controlled to be further preferably 0.9-0.99 in the preset range. So that the nitrogen oxides adsorbed by the lean NOx trap 6 are released and react with the reducing agent in the exhaust gas of the engine 1 to produce nitrogen gas harmless to the environment when the exhaust gas of the engine 1 is in a rich reducing atmosphere.

The second working mode comprises a second working mode and a third working mode, and one of the modes is selected according to actual conditions in working.

The device for reducing sulfur and regenerating sulfur in the first working mode and the second working mode is a sulfur reduction catalyst.

The processing of the exhaust gas of the engine 1 in the first operating mode or the second operating mode, and the obtaining of the processed first exhaust gas specifically includes:

treating the tail gas of the engine 1 through a first working mode, a second working mode or a third working mode to obtain a treated first tail gas;

the treatment of the exhaust gas of the engine 1 by the second working mold specifically comprises:

and the exhaust gas of the engine 1 is treated in the second or third working mode.

Whether nitrogen oxide exists in first tail gas obtained after the tail gas of the engine 1 is treated in a first working mode, a second working mode or a third working mode is detected and judged through the NOx sensor 19;

when no nitrogen oxides are present in the first exhaust gas, indicating that NOx can be adsorbed, the exhaust gas of the engine 1 may be treated using the operation mode.

When nitrogen oxides are present in the first exhaust gas, that is, the adsorption of NOx is incomplete, the lean NOx trap 6 cannot adsorb NOx as required, and therefore, it is necessary to switch to the second operation mode or the third operation mode. In the second working mode, the excess air coefficient in the tail gas of the engine 1 is controlled within a preset range, namely, under the reducing atmosphere rich in combustion in the tail gas of the engine 1, the nitrogen oxide adsorbed by the lean NOx trap is released and reacts with the reducing agent in the tail gas of the engine 1 to generate nitrogen harmless to the environment, namely, the adsorbed nitrate on the lean NOx trap 6 is decomposed to release NOx, and the NOx is further reduced to N by the reducing agent ₂ Thereby regenerating the lean NOx trap 6. When the second operating mode is to detect and judge the first exhaust gas again through the first exhaust gas obtained by processing the exhaust gas of the engine 1, when no nitrogen oxide exists in the first exhaust gas, that is, after the regeneration of the lean NOx trap 6 is completed, the second operating mode is switched back to the operating mode to process the exhaust gas of the engine 1 again.

Wherein, the treatment of the tail gas of the engine 1 through the second working mold specifically comprises:

judging whether the sulfur content exceeds a preset desulfurization threshold value or not;

the preset desulfurization threshold is set in relation to the sulfur reduction catalyst 4, and is generally set to a value range of 75% -85% of the maximum stored sulfur content of the sulfur reduction catalyst 4. The purpose of determining whether the sulfur content in the sulfur reduction catalyst 4 exceeds the desulfurization threshold value is to determine the operation of the sulfur reduction catalyst 4.

And when the sulfur content does not exceed the preset desulfurization threshold value, treating the tail gas of the engine 1 through the working mode.

When the sulfur content does not exceed the preset desulfurization threshold, it can be known that the sulfur reduction catalyst 4 does not enter a saturated state, and the operation of sulfur reduction adsorption on the exhaust gas of the engine 1 can be continued. Thus, only the exhaust gas of the engine 1 in the second operating mode needs to be treated to regenerate the lean NOx trap 6 for subsequent reuse of the lean NOx trap 6.

After the step of judging whether the sulfur content exceeds a preset desulfurization threshold value, the method further comprises the following steps:

when the sulfur content exceeds the preset desulfurization threshold, acquiring the temperature of the tail gas of the engine 1;

when the sulfur content exceeds the preset desulfurization threshold, it can be known that the sulfur reduction catalyst 4 is about to enter a saturated state, and the sulfur reduction catalyst 4 needs to be regenerated so as to reuse the sulfur reduction catalyst 4 later.

Judging whether the temperature of the tail gas of the engine 1 exceeds a preset temperature threshold value or not;

whether the condition for desulfurization regeneration by the sulfur reduction catalyst 4 is satisfied, that is, whether the exhaust gas of the engine 1 is a high-temperature exhaust gas that is rich in fuel and suitable for desulfurization is determined by obtaining the temperature of the exhaust gas of the engine 1. The value range of the preset temperature threshold is 550-650 degrees.

And when the temperature of the tail gas of the engine 1 exceeds a preset temperature threshold value, treating the tail gas of the engine 1 through the third working mode.

When the temperature of the exhaust gas of the engine 1 exceeds the preset temperature threshold, that is, the exhaust gas of the engine 1 is rich-burning high-temperature exhaust gas suitable for desulfurization, and meets the condition of desulfurization regeneration of the sulfur reduction catalyst 4, the operation mode is switched to the third operation mode, and the sulfur reduction catalyst 4 is desulfurized and regenerated while the lean NOx trap 6 is regenerated, so that the exhaust gas can be continuously used when the operation mode is switched to the first operation mode.

After judging whether the temperature of the exhaust gas of the engine 1 exceeds a preset temperature threshold, the method further comprises the following steps:

and when the temperature of the tail gas of the engine 1 does not exceed the preset temperature threshold, the ignition angle is postponed to a preset angle for ignition, and whether the temperature of the tail gas of the engine 1 exceeds the preset temperature threshold is judged again.

When the temperature of the exhaust gas of the engine 1 does not exceed the preset temperature threshold, the temperature of the exhaust gas of the engine 1 is not rich and the exhaust gas of the engine 1 is suitable for desulfurization, that is, the condition of desulfurization regeneration of the sulfur reduction catalyst 4 is not met, therefore, the temperature of the exhaust gas of the engine 1 is raised by repeatedly retarding the ignition angle to the preset angle until the temperature of the exhaust gas of the engine 1 exceeds the preset temperature threshold, so that the exhaust gas of the engine 1 is rich and the exhaust gas of the engine 1 is suitable for desulfurization, that is, the condition of desulfurization regeneration of the sulfur reduction catalyst 4 is met, and then the operation mode is switched to the third operation mode, the sulfur reduction catalyst 4 is regenerated while the lean NOx trap 6 is regenerated, so that the exhaust gas is continuously used when the operation mode is switched to the first operation mode.

Wherein the ignition angle is retarded to a preset angle ignition by controlling the ignition plug 21 of the engine 1. The value range of the preset angle is 1-3 degrees CA.

In addition, in the tail gas treatment of the engine 1, the first working mode is a main working mode and accounts for about 75 percent of the working running time of the whole sulfur reduction treatment;

the second working mode is a secondary working mode and accounts for about 24 percent of the working running time of the whole sulfur reduction treatment;

because the tail gas of the engine 1 contains less sulfur components, the sulfur content absorbed in the sulfur reduction catalyst 4 is difficult to exceed the preset desulfurization threshold value in a short time during normal use. Therefore, the third working mode only accounts for about 1 percent of the working running time of the whole sulfur reduction treatment.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one type of logical functional division, and other divisions may be realized in practice, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The device for treating the automobile exhaust is characterized by comprising an electronic control unit, a first exhaust pipe, a second exhaust pipe, a third exhaust pipe, a fourth exhaust pipe, a sulfur reduction catalyst, a lean-burn NOx trap, a NOx sensor, a first flow dividing valve and a second flow dividing valve, wherein the first exhaust pipe, the sulfur reduction catalyst, the second exhaust pipe, the lean-burn NOx trap and the third exhaust pipe are sequentially connected, the NOx sensor is arranged on the third exhaust pipe, and one end, far away from the sulfur reduction catalyst, of the first exhaust pipe is connected with the exhaust end of an engine;

the electronic control unit is respectively and electrically connected with the first flow dividing valve, the second flow dividing valve, the NOx sensor and a fuel injector on the engine and is used for controlling the tail gas treatment working mode of the automobile;

the treatment device further comprises a temperature sensor, a sulfur dioxide sensor, a fifth exhaust pipe, a sixth exhaust pipe, a third diverter valve, a fourth diverter valve and a first valve, wherein the temperature sensor is arranged on the first exhaust pipe, and the sulfur dioxide sensor is arranged on the first exhaust pipe;

2. The vehicle exhaust gas treatment device according to claim 1, wherein the electronic control unit is electrically connected to a spark plug on the engine.

3. The vehicle exhaust gas treatment device according to claim 1, further comprising a check valve provided on the sixth exhaust pipe.

4. The automobile exhaust gas treatment device according to claim 1, wherein the sulfur reduction catalyst comprises a catalyst and an adsorbent.

5. The apparatus of claim 4, wherein the adsorbent is a non-alkali metal.

6. A treatment method for automobile exhaust is characterized by comprising the following steps:

judging whether nitrogen oxides exist in the first tail gas or not;

wherein:

7. The method for treating the automobile exhaust according to claim 6, wherein the step of treating the exhaust of the engine through the second working mold specifically comprises the steps of:

8. The method for treating automobile exhaust according to claim 7, wherein the second operation mode further includes a third operation mode for regenerating the lean NOx trap and desulfurizing the sulfur reduction catalyst in an environment where an excess air ratio in the exhaust of the engine is controlled within a preset range and an exhaust temperature of the engine is controlled to be higher than a preset temperature threshold;

the treatment of the tail gas of the engine through the second working die specifically comprises the following steps:

9. The method for treating automobile exhaust according to claim 7, wherein the determining whether the sulfur content exceeds a preset desulfurization threshold further comprises:

10. The method for treating automobile exhaust according to claim 9, wherein after determining whether the temperature of the exhaust of the engine exceeds a preset temperature threshold, the method further comprises:

11. The method for treating automobile exhaust according to claim 7, wherein the preset desulfurization threshold value ranges from 75% to 85% of the maximum stored sulfur content of the sulfur reduction catalyst.

12. The method of claim 6, wherein the excess air ratio in the exhaust gas of the engine is controlled to be less than 1 in a preset range.

13. The method of treating automobile exhaust according to claim 12, wherein the excess air ratio in the exhaust of the engine is controlled to be in a preset range of 0.9 to 0.99.

14. The method for treating automobile exhaust according to claim 10, wherein the preset temperature threshold is set to a value ranging from 550 degrees to 650 degrees.

15. The method for treating automobile exhaust according to claim 10, wherein the preset angle is in a range of 1 to 3 ° CA.