CN215408814U

CN215408814U - Exhaust device and vehicle

Info

Publication number: CN215408814U
Application number: CN202121594833.7U
Authority: CN
Inventors: 刘世龙
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2021-07-12
Filing date: 2021-07-12
Publication date: 2022-01-04
Anticipated expiration: 2031-07-12

Abstract

The embodiment of the application provides an exhaust device and a vehicle, and the exhaust device comprises a lean NOx trap, a diesel particulate filter and a selective catalytic reduction system, wherein the lean NOx trap is communicated with the diesel particulate filter through a first pipeline, and the selective catalytic reduction system is communicated with the diesel particulate filter through a second pipeline; one end of the bypass pipeline is communicated with the first pipeline, and the other end of the bypass pipeline is communicated with the second pipeline; the valve group is used for switching the bypass pipeline to a communication state or a closed state; through exhaust apparatus and vehicle that this application embodiment provided, can make full use of LNT at the ammonia that desorption process and reduction in-process produced.

Description

Exhaust device and vehicle

Technical Field

The embodiment of the application relates to the technical field of automobiles, in particular to an exhaust device and a vehicle.

Background

The exhaust pollutants of diesel engines are mainly NOx and PM, and according to advanced development experience of developed countries in the automobile industry, exhaust aftertreatment technology must be combined to control the emission of NOx and PM, and generally, two common technologies are available for treating the NOx pollutants: LNT (Lean NOx Trap) and SCR (selective catalytic reduction), and a Diesel Particulate Filter (DPF) is further disposed between the LNT and the SCR.

Tail gas has a desorption process and reduction process on LNT, and in this desorption process and reduction process, if the quantity of reductant is surplus, can take place remaining side reaction on the LNT, produces the ammonia, and the ammonia can be used for converting NOx in SCR, but the ammonia can be oxidized after getting into DPF to lead to the ammonia to be wasted completely.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides an exhaust device and a vehicle, and aims to fully utilize ammonia generated by an LNT in a desorption process and a reduction process.

The first aspect of the embodiments of the present application provides an exhaust apparatus, including a lean NOx trap, a diesel particulate filter, and a selective catalytic reduction system, where the lean NOx trap and the diesel particulate filter are communicated with each other through a first pipeline, and the selective catalytic reduction system and the diesel particulate filter are communicated with each other through a second pipeline;

one end of the bypass pipeline is communicated with the first pipeline, and the other end of the bypass pipeline is communicated with the second pipeline;

the valve group is used for switching the bypass pipeline to a communication state or a closed state;

when the lean NOx trap is subjected to desorption and reduction processes, the valve group enables the bypass pipeline to be switched to a communication state, so that tail gas passes through the selective catalytic reduction system from the lean NOx trap through the bypass pipeline;

when the lean NOx trap is not subjected to desorption and reduction processes, the valve group enables the bypass pipeline to be switched to a closed state, so that tail gas enters the selective catalytic reduction system from the lean NOx trap through the diesel particle filter.

Optionally, the valve set comprises a first valve and a second valve;

the first valve is arranged at a position where the bypass pipeline is communicated with the first pipeline; the second valve is arranged at a position where the bypass line communicates with the second line;

after the first valve and the second valve are opened, the bypass pipeline is communicated with the first pipeline and the second pipeline, and the positions of the first pipeline and the second pipeline, which are connected with the diesel particulate filter, are closed;

after the first valve and the second valve are closed, the bypass pipeline is closed with the first pipeline and the second pipeline, and the positions of the first pipeline and the second pipeline connected with the diesel particulate filter are communicated.

Optionally, the first valve and the second valve are respectively connected with the control device in a telecommunication way, and the control device is used for controlling the first valve and the second valve to be opened or closed.

Optionally, detection means for detecting an operating state of the lean NOx trap;

the control means controls the first valve and the second valve to open or close in response to the operating state of the lean NOx trap detected by the detection means.

Optionally, a filter is disposed on the bypass line.

Optionally, the filter is detachably connected to the bypass line.

Optionally, a mounting portion is disposed on the bypass pipeline, the mounting portion includes a connecting flange, and the filter is connected to the bypass pipeline through the connecting flange.

A second aspect of an embodiment of the present application provides a vehicle including an exhaust apparatus as provided in the first aspect of an embodiment of the present application.

Has the advantages that:

the application provides an exhaust device and a vehicle, wherein a bypass pipeline is arranged on a first pipeline and a second pipeline, when a lean NOx trap is not subjected to desorption and reduction processes, the bypass pipeline is closed, and at the moment, tail gas passes through a diesel particle filter from the lean NOx trap and then enters a selective catalytic reduction system for treatment; when the lean NOx trap is subjected to desorption and reduction processes, the bypass pipeline is communicated, so that tail gas can directly enter the selective catalytic reduction system from the lean NOx trap, ammonia gas produced in the lean NOx trap can enter the selective catalytic reduction system and participate in reduction reaction in the selective catalytic reduction system to convert NOx, the ammonia gas is not wasted, the ammonia gas produced in the desorption and reduction processes of the lean NOx trap can be fully utilized, and the conversion efficiency of the selective catalytic reduction system to NOx can be improved.

Drawings

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

Fig. 1 is a schematic structural diagram of an exhaust apparatus according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a bypass line of an exhaust system according to an embodiment of the present disclosure in a connected state;

fig. 3 is a schematic structural diagram of a bypass line of an exhaust device according to an embodiment of the present application in a closed state.

Description of reference numerals: 1. a first pipeline; 2. a second pipeline; 3. a bypass line; 4. a valve group; 41. a first valve; 42. a second valve; 5. and (3) a filter.

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 some, but not all, embodiments of the present application. 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 related art, an exhaust device of a vehicle generally includes a lean NOx trap, a diesel particulate filter, and a selective catalytic reduction system; hereinafter, LNT stands for lean NOx trap, DPF stands for diesel particulate filter, and SCR stands for selective catalytic reduction system.

Wherein the LNT absorbs NOx from the exhaust under certain conditions and reduces NOx to N using enrichment conditions when the absorbed NOx reaches a maximum capacity₂And O₂. LNT catalysts generally use noble metal Pt as the catalytically active component, alkali and/or alkaline earth metal oxides as the storage component, and gamma-Al with a large specific surface area₂O₃As a carrier to improve dispersion of the active and storage components. Typical LNT catalyst systems are Pt, BaO or Al₂O₃。

NOx is reduced to N during lean NOx storage and rich NOx storage on LNT catalyst₂The principle of (1) is as follows:

first, during the relatively long (about 60-90 seconds) lean burn phase, NO is oxidized to NO on the noble metal active sites Pt₂Then NO₂Reacting with adjacent basic component BaO to generate nitrate and storing; when the engine is switched to a rich atmosphere, the concentrations of the reducing components HC, CO and H2 in the exhaust gas are rapidly increased in a short time (about 3-5 seconds), the stored nitrates in the reducing atmosphere are thermally unstable, N02 is rapidly released and is catalytically reduced to N2 by the reducing agent, and the catalyst storage site is regenerated, thereby completing a standard circulation process of the LNT.

The reactions that take place on the catalyst by the adsorption process are as follows:

2NO+O₂→2NO₂

the reactions that occur on the catalyst during desorption and reduction are as follows:

Ba(NO₃)₂→BaO+NO₂

BaO+CO₂→BaCO₃

if the amount of reductant is excessive during desorption and reduction, the rest of the side reactions on the LNT will occur:

the basic working principle of the SCR is as follows: when the engine runs, urea aqueous solution is sprayed into an exhaust pipe of the engine, and the urea aqueous solution generates hydrolysis reaction in high-temperature exhaust to generate NH₃(or released as solid ammonia), NH₃With NO and NO under the action of catalyst₂Chemical reaction occurs to achieve the purpose of removing NOx.

Urea is formed into NH3 by two steps of pyrolysis and hydrolysis starting from 160 ℃:

pyrolysis: CO (NH)₂)₂→NH₃+HNCO

Hydrolysis: HNCO + H₂O→NH₃+CO₂

The main chemical reactions inside the SCR are:

4NH₃+4NO+O₂→4N₂+6H₂o (Medium speed SCR reaction)

2NH₃+4NO+NO₂→2N₂+3H₂O (Rapid SCR reaction)

4NH₃+2NO₂+O₂→3N₂+6H₂O (Slow SCR reaction)

The main chemical reaction in SCR described above shows that the purpose of removing NOx is achieved by NH3 in SCR.

However, due to the ability of the precious metal coating on the DPF carrier to oxidize, the LNT will produce NH relative to the "excess" reductant HC during desorption and reduction₃Will be oxidized to N in the DPF₂And H₂O, is completely wasted.

In view of the above, the present disclosure provides an exhaust apparatus and a vehicle, in which a bypass pipeline is disposed on a first pipeline and a second pipeline, when a lean NOx trap is not undergoing desorption and reduction processes, the bypass pipeline is closed, and at this time, exhaust gas passes through a diesel particulate filter from the lean NOx trap and then enters a selective catalytic reduction system for treatment; when the lean NOx trap is subjected to desorption and reduction processes, the bypass pipeline is communicated, so that tail gas can directly enter the selective catalytic reduction system from the lean NOx trap, ammonia gas produced in the lean NOx trap can enter the selective catalytic reduction system and participate in reduction reaction in the selective catalytic reduction system to convert NOx, the ammonia gas is not wasted, the ammonia gas produced in the desorption and reduction processes of the lean NOx trap can be fully utilized, and the conversion efficiency of the selective catalytic reduction system to NOx can be improved.

Example one

Referring to FIG. 1, an exhaust apparatus including a lean NOx trap, a diesel particulate filter, and a selective catalytic reduction system is disclosed in an embodiment of the present application; hereinafter, LNT stands for lean NOx trap, DPF stands for diesel particulate filter, and SCR stands for selective catalytic reduction system.

The LNT is communicated with the DPF through a first pipeline 1, and the SCR is communicated with the DPF through a second pipeline 2.

Referring to fig. 1, the exhaust apparatus further includes a bypass line 3 and a valve group 4. Wherein, one end of the bypass pipeline 3 is communicated with the first pipeline 1, and the other end is communicated with the second pipeline 2; the valve group 4 is used for switching the bypass pipeline 3 to a communication state or a closed state.

Specifically, when the LNT is subjected to desorption and reduction processes, the valve group 4 switches the bypass line 3 to a communication state, so that the exhaust gas enters the SCR from the LNT through the bypass line 3; when the LNT is not in desorption and reduction, the valve group 4 switches the bypass pipeline 3 to a closed state, so that the tail gas enters the SCR from the LNT through the DPF.

Like this, when LNT carries out desorption and reduction process, if the quantity of reductant is surplus for LNT takes place the side reaction and generates the ammonia, and this part ammonia can get into SCR through bypass pipeline 3, and then participates in the reduction reaction in the SCR, and can not be oxidized by DPF, thereby make full use of LNT the ammonia that generates when carrying out desorption and reduction process, also improved SCR simultaneously to NOx's conversion efficiency.

In one embodiment, referring to fig. 2, the valve set 4 includes a first valve 41 and a second valve 42, and the first valve 41 and the second valve 42 are controlled to communicate and close the bypass line 3.

Specifically, referring to fig. 2, the first valve 41 is rotatably connected to a position where the bypass line 3 communicates with the first line 1, and the second valve 42 is rotatably connected to a position where the bypass line 3 communicates with the second line 2. When the LNT is undergoing desorption and reduction, the first valve 41 and the second valve 42 are simultaneously switched to the open state; when the LNT is not undergoing the desorption and reduction process, the first valve 41 and the second valve 42 are simultaneously switched to the closed state.

Referring to fig. 2, the open state refers to a state in which the first valve 41 and the second valve 42 are respectively rotated into the first pipeline 1 and the second pipeline 2, when both the first valve 41 and the second valve 42 are in the open state, the bypass pipeline 3 is simultaneously communicated with the first pipeline 1 and the second pipeline 2, and the positions where the first pipeline 1 and the second pipeline 2 are connected with the DPF are closed, at this time, gas coming out of the LNT cannot enter the DPF but only enters the bypass pipeline 3, and finally enters the SCR.

Referring to fig. 3, the closed state refers to a state where the first valve 41 and the second valve 42 are rotated to a position where the bypass pipeline 3 is communicated, when both the first valve 41 and the second valve 42 are in the closed state, both ends of the bypass pipeline 3 are respectively closed by the first valve 41 and the second valve 42, so that the bypass pipeline 3 is completely closed, and positions where the first pipeline 1 and the second pipeline 2 are connected to the DPF are in the communicated state, at this time, gas coming out of the LNT enters the DPF and then enters the SCR.

In this way, the switching between the communication state and the closed state of the bypass pipeline 3 is realized by the position change of the first valve 41 and the second valve 42, so that ammonia gas generated by the LNT during desorption and reduction processes can completely enter the SCR to participate in the reduction reaction.

In one embodiment, the exhaust device further comprises a control device (not shown) electrically connected to the first valve 41 and the second valve 42, respectively, for controlling the first valve 41 and the second valve 42 to open or close.

Specifically, when the LNT is subjected to desorption and reduction processes, the control device controls the first valve 41 and the second valve 42 to be opened, so that the bypass pipeline 3 is communicated with the first pipeline 1 and the second pipeline 2, and the positions where the first pipeline 1 and the second pipeline 2 are connected with the DPF are closed, at this time, ammonia generated by the LNT during desorption and reduction processes enters the SCR through the bypass pipeline 3 to participate in the reduction reaction.

When the LNT is not desorbed and reduced, the control device controls the first valve 41 and the second valve 42 to close, so that the bypass pipeline 3, the first pipeline 1 and the second pipeline 2 are closed, the positions of the first pipeline 1 and the second pipeline 2 connected with the DPF are communicated, and at the moment, the gas coming out of the LNT can enter the SCR after being filtered by the DPF.

In a specific application, the Control device may be one of Control units of a vehicle ECU (Electronic Control Unit).

In one embodiment, the exhaust device further comprises a detection device (not shown) for detecting the operation state of the LNT and causing the control device to control the first valve 41 and the second valve 42 to open or close.

Specifically, when the detection device detects that the LNT performs the desorption and reduction process, the control device responds to the detection device, controls the first valve 41 and the second valve 42 to be opened, and at the moment, the bypass pipeline 3 is communicated with the first pipeline 1 and the second pipeline 2, and the positions where the first pipeline 1 and the second pipeline 2 are connected with the DPF are closed, so that ammonia gas generated when the LNT performs the desorption and reduction process enters the SCR through the bypass pipeline 3 to participate in the reduction reaction.

In this step, the detecting device can also detect the content of ammonia gas, and when the content of ammonia gas is greater than a preset content value, for example, 20ppm, the control device can control the first valve 41 and the second valve 42 to open.

When the detection device detects that the LNT does not perform the desorption and reduction processes, the control device responds to the detection device and controls the first valve 41 and the second valve 42 to be closed, at the moment, the bypass pipeline 3, the first pipeline 1 and the second pipeline 2 are closed, the positions of the first pipeline 1 and the second pipeline 2 connected with the DPF are communicated, and gas coming out of the LNT can enter the SCR after being filtered by the DPF.

In a specific application, the detection device may be one of detection units of a vehicle ECU.

In one embodiment, since the gas from the LNT may contain diesel particles, and after the diesel particles enter the SCR through the bypass line 3, there is a risk of blocking the SCR or increasing the PM emission of the vehicle to be out of standard, in order to avoid the above problem, referring to fig. 2, a filter 5 is disposed on the bypass line 3.

The filter 5 can filter diesel particulates to reduce the diesel particulates entering the SCR, thus reducing the probability of problems such as SCR plugging or vehicle PM emissions being out of specification.

In a specific application, the filter 5 needs to adopt a high temperature resistant filter 5, such as a metal filter 5 or a ceramic filter 5, because the gas temperature from the LNT is high, generally 200-300 ℃.

In one embodiment, the filter 5 is detachably connected to the bypass line 3 in order to facilitate replacement of the filter 5.

Therefore, after the filter 5 is used for a period of time, the filter 5 can be detached from the bypass pipeline 3 and then is mounted on the bypass pipeline 3 again after being cleaned, so that the filter 5 is more convenient to use, and the filter 5 can be ensured to have a better filtering effect all the time.

In one embodiment, a mounting portion (not shown) is provided on the bypass line 3, the mounting portion including a connecting flange (not shown) by which the filter 5 is connected to the bypass line 3.

Specifically, a part of the bypass line 3 may be cut off, the filter 5 may be attached to the part as an attachment portion, a connection flange may be provided at a position where the bypass line 3 is cut off, and the filter 5 and the bypass line 3 may be connected to each other via the connection flange when the filter 5 is attached.

Example two

Based on the same inventive concept, the embodiment of the application discloses a vehicle which comprises an exhaust device provided by the first embodiment of the application.

It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.

It should also be noted that, in this document, 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 present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Moreover, relational terms such as "first" and "second" are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions or should not be construed as indicating or implying relative importance. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or terminal equipment comprising the element.

The technical solutions provided by the present application are described in detail above, and the principles and embodiments of the present application are described herein by using specific examples, which are only used to help understanding the present application, and the content of the present description should not be construed as limiting the present application. While various modifications of the illustrative embodiments and applications will be apparent to those skilled in the art based upon this disclosure, it is not necessary or necessary to exhaustively enumerate all embodiments, and all obvious variations and modifications can be resorted to, falling within the scope of the disclosure.

Claims

1. An exhaust apparatus comprising a lean NOx trap, a diesel particulate filter, and a selective catalytic reduction system, characterized in that:

the lean NOx trap is communicated with the diesel particulate filter through a first pipeline (1), and the selective catalytic reduction system is communicated with the diesel particulate filter through a second pipeline (2);

the bypass pipeline (3), one end of the bypass pipeline (3) is communicated with the first pipeline (1), and the other end of the bypass pipeline (3) is communicated with the second pipeline (2);

the valve group (4) is used for switching the bypass pipeline (3) to a communication state or a closed state;

when the lean NOx trap is subjected to desorption and reduction processes, the valve group (4) enables the bypass pipeline (3) to be switched to a communication state, so that tail gas enters the selective catalytic reduction system from the lean NOx trap through the bypass pipeline (3);

when the lean NOx trap is not subjected to desorption and reduction processes, the valve group (4) enables the bypass pipeline (3) to be switched to a closed state, so that tail gas enters the selective catalytic reduction system from the lean NOx trap through the diesel particle filter.

2. The exhaust apparatus according to claim 1, characterized in that:

the valve group (4) comprises a first valve (41) and a second valve (42);

the first valve (41) is arranged at a position where the bypass pipeline (3) is communicated with the first pipeline (1); the second valve (42) is arranged at a position where the bypass pipeline (3) is communicated with the second pipeline (2);

after the first valve (41) and the second valve (42) are opened, the bypass pipeline (3) is communicated with the first pipeline (1) and the second pipeline (2), and the positions where the first pipeline (1) and the second pipeline (2) are connected with the diesel particulate filter are closed;

after the first valve (41) and the second valve (42) are closed, the bypass pipeline (3) is closed with the first pipeline (1) and the second pipeline (2), and the positions of the first pipeline (1) and the second pipeline (2) connected with the diesel particulate filter are communicated.

3. The exhaust apparatus according to claim 2, characterized in that:

the first valve (41) and the second valve (42) are respectively in telecommunication connection with the control device, and the control device is used for controlling the first valve (41) and the second valve (42) to be opened or closed.

4. The exhaust apparatus according to claim 3, characterized in that:

detection means for detecting an operating state of the lean NOx trap;

the control device controls the first valve (41) and the second valve (42) to be opened or closed in response to the operating state of the lean NOx trap detected by the detection device.

5. The exhaust apparatus according to claim 1, characterized in that:

and a filter (5) is arranged on the bypass pipeline (3).

6. The exhaust apparatus according to claim 5, characterized in that:

the filter (5) is detachably connected to the bypass pipeline (3).

7. The exhaust apparatus according to claim 6, characterized in that:

the filter is characterized in that an installation part is arranged on the bypass pipeline (3) and comprises a connecting flange, and the filter (5) is connected to the bypass pipeline (3) through the connecting flange.

8. A vehicle, characterized in that:

comprising an exhaust device according to any of claims 1-7.