CN113027577B - Engine exhaust device and engine exhaust method - Google Patents

Engine exhaust device and engine exhaust method Download PDF

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Publication number
CN113027577B
CN113027577B CN202110450153.6A CN202110450153A CN113027577B CN 113027577 B CN113027577 B CN 113027577B CN 202110450153 A CN202110450153 A CN 202110450153A CN 113027577 B CN113027577 B CN 113027577B
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bypass
temperature
control valve
branch
doc
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CN113027577A (en
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张勇
褚国良
房瑞雪
王明明
齐骏
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Weichai Power Co Ltd
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Weichai Power Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

The invention discloses an engine exhaust device and an engine exhaust method, and relates to the technical field of engine tail gas treatment. This engine exhaust apparatus includes main line, bypass pipeline, first temperature sensor and second temperature sensor, has connected gradually booster, DOC, DPF and SCR in the main line, and the one end of bypass pipeline is connected between booster and DOC, and the other end of bypass pipeline can communicate with DPF's air inlet. The first temperature sensor is arranged between the supercharger and the DOC and used for detecting the temperature of the exhaust gas entering the DOC; a second temperature sensor is disposed between the DPF and the SCR for sensing a temperature of exhaust gas entering the SCR. The air outlet of the supercharger can be selectively communicated with the air inlet of the DOC or the bypass pipeline. The exhaust device of the engine not only avoids low oxidation efficiency caused by too fast aging of DOC, but also ensures the conversion efficiency of SCR, thereby ensuring that the emission of waste gas meets the requirements.

Description

Engine exhaust device and engine exhaust method
Technical Field
The invention relates to the technical field of engine tail gas treatment, in particular to an engine exhaust device and an engine exhaust method.
Background
SCR (Selective Catalytic Reduction) is an exhaust gas treatment technology widely used in the treatment of diesel engine exhaust gas, and NO in the exhaust gas can be reduced by providing SCRxThe Oxidation reaction is effectively inhibited while the accelerated reduction is carried out, DOC (Diesel Oxidation Catalyst) is a technology which provides high temperature for DPF (Diesel Particulate Filter) regeneration by oxidizing Diesel oil to release heat, and can realize the Oxidation of NO in exhaust gas to NO2Increase NO2In NOxThe ratio of (1).
In current engine exhaust treatment systems, a DOC is placed before the DPF and SCR for converting CO and HC in the exhaust gas to harmless H 20 and CO2And oxidizing NO in the exhaust gas to NO2Accelerating the subsequent SCR to NOxThe conversion speed and efficiency, and the fuel oil injected to the DOC in a catalytic oxidation mode, and the temperature in the DOC is increased through the combustion of the fuel oil, so that early preparation is made for the regeneration of the DOC. The DOC carrier is heated by the exhaust gas first, so that the SCR temperature rises slowly at low temperature, and urea is not injected or the injection amount of the urea is small. In order to solve the problem, a bypass pipeline connected with a DOC in parallel is added at the upstream of a supercharger in the prior art, and exhaust gas is discharged into the atmosphere through a DPF and an SCR at low temperature, but the DPF is blocked; and when high temperature, waste gas discharges into the atmosphere through DOC, DPF and SCR, and the temperature through DOC is too high, easily causes DOC ageing.
Disclosure of Invention
The invention aims to provide an engine exhaust device and an engine exhaust method, which can prevent DOC (diesel engine control) from aging and avoid DPF blockage caused when exhaust gas is discharged into the atmosphere through a DPF and an SCR (selective catalytic reduction).
In order to achieve the purpose, the invention adopts the following technical scheme:
an engine exhaust device comprises a main pipeline, a bypass pipeline, a first temperature sensor and a second temperature sensor, wherein a supercharger, a DOC, a DPF and an SCR are sequentially connected in the main pipeline, one end of the bypass pipeline is connected between the supercharger and the DOC, and the other end of the bypass pipeline can be communicated with an air inlet of the DPF; the first temperature sensor is disposed between the supercharger and the DOC, and the second temperature sensor is disposed between the DPF and the SCR; the air outlet of the supercharger can be selectively communicated with the air inlet of the DOC or the bypass pipeline.
Optionally, the bypass pipeline includes a total air inlet and a bypass first branch, the total air inlet is disposed between the supercharger and the DOC, the air inlet of the bypass first branch can be communicated with the total air inlet, and the air outlet of the bypass first branch can be communicated with the air inlet of the DPF.
Optionally, a first control valve is arranged on the bypass first branch, and the first control valve is used for controlling on-off of the bypass first branch.
Optionally, the bypass pipeline further includes a bypass second branch and a total gas outlet, the gas inlet of the bypass second branch can be communicated with the gas outlet of the DPF, the gas outlet of the bypass second branch can be communicated with the total gas outlet, and the total gas outlet is disposed at the downstream of the SCR and can be communicated with the atmosphere.
Optionally, a second control valve is arranged on the bypass second branch, and the second control valve is used for controlling the on-off of the bypass second branch; a third control valve is arranged between the air inlet of the bypass first branch and the air outlet of the bypass second branch and is used for controlling whether the main air inlet is communicated with the air outlet of the bypass second branch or not; and a fourth control valve is also arranged on the main pipeline and is used for controlling whether the air outlet of the DPF is communicated with the air inlet of the SCR or not.
Optionally, the fourth control valve is disposed between the intake port of the bypass second branch and the intake port of the SCR.
Optionally, the main pipeline is further provided with a fifth control valve, and the fifth control valve is arranged between the gas outlet of the supercharger and the gas inlet of the DOC and is used for controlling whether the gas outlet of the supercharger is communicated with the gas inlet of the DOC.
Optionally, the main pipeline is further provided with a sixth control valve, and the sixth control valve is used for controlling whether the gas outlet of the DOC is communicated with the gas inlet of the bypass first branch and whether the gas outlet of the DOC is communicated with the gas inlet of the DPF.
An engine exhaust method is applied to the engine exhaust device of any one of the above items, the engine exhaust device comprises a main pipeline, a bypass pipeline, a first temperature sensor and a second temperature sensor, a supercharger, a DOC, a DPF and an SCR are sequentially connected in the main pipeline, the bypass pipeline comprises a main air inlet, a bypass first branch, a bypass second branch and a main air outlet, the main air inlet and the first temperature sensor are both arranged between the supercharger and the DOC, the second temperature sensor is arranged between the DPF and the SCR, and the main air outlet is arranged at the downstream of the SCR and can be communicated with the atmosphere; the engine exhaust method includes:
when the engine is in a reverse dragging working condition:
when the temperature detected by the second temperature sensor is lower than a first preset temperature and the temperature detected by the first temperature sensor is higher than the temperature detected by the second temperature sensor, controlling the exhaust gas to be discharged into the atmosphere through the supercharger, the main air inlet, the bypass first branch, the DPF and the SCR;
when the temperature detected by the first temperature sensor is higher than or equal to a second preset temperature, the first preset temperature is lower than the second preset temperature, and exhaust gas is controlled to be discharged into the atmosphere through the supercharger, the total air inlet, the bypass first branch, the DPF and the SCR.
Optionally, the first preset temperature is a minimum temperature at which the SCR can sufficiently react, and the second preset temperature is a minimum temperature at which the DOC can be aged.
Optionally, when the temperature detected by the second temperature sensor is lower than a first preset temperature and the temperature detected by the first temperature sensor is lower than or equal to the temperature detected by the second temperature sensor, controlling the exhaust gas to be discharged into the atmosphere through the supercharger, the main air inlet, the bypass first branch, the DPF, the bypass second branch and the main air outlet under the non-reverse-dragging working condition of the engine.
Optionally, exhaust gas is controlled to be exhausted to the atmosphere through the supercharger, the main air inlet and the main air outlet when the engine is in a reverse-dragging condition.
The invention has the beneficial effects that:
the invention provides an engine exhaust device, wherein one end of a bypass pipeline is connected between a supercharger and a DOC, the other end of the bypass pipeline can be communicated with an air inlet of a DPF, and an air outlet of the supercharger can be selectively communicated with the air inlet of the DOC or the bypass pipeline. The first temperature sensor is used for detecting the temperature of the exhaust gas entering the DOC; a second temperature sensor is used to detect the temperature of the exhaust gas entering the SCR. Through the monitoring to the exhaust gas temperature who gets into DOC and the exhaust gas temperature who gets into SCR, the discharge route of control waste gas had both avoided DOC's the oxidation inefficiency that ageing leads to at the excessive speed, had guaranteed SCR's conversion efficiency again to make the emission of waste gas satisfy the demands.
According to the engine exhaust method provided by the invention, when the temperature detected by the second temperature sensor is lower than the first preset temperature and the temperature detected by the first temperature sensor is higher than the temperature detected by the second temperature sensor, namely the temperature of the upstream of the SCR is lower than the first preset temperature and the temperature of the upstream of the DOC is higher than the temperature of the upstream of the SCR, in order to ensure the conversion efficiency of the SCR, avoid the heat loss of the exhaust gas generated by the DOC, and control the exhaust gas to be exhausted into the atmosphere through the supercharger, the total air inlet, the bypass first branch, the DPF and the SCR. In order to avoid the oxidation efficiency reduction caused by the fact that the aging speed of the DOC is accelerated by high temperature, when the temperature detected by the first temperature sensor is higher than or equal to the second preset temperature, the first preset temperature is lower than the second preset temperature, and the waste gas is discharged into the atmosphere through the supercharger, the total air inlet, the bypass first branch, the DPF and the SCR. The engine exhaust method provided by the invention can reduce the DOC aging speed and ensure the conversion efficiency of SCR.
Drawings
FIG. 1 is a schematic structural diagram of an engine exhaust system according to an embodiment of the present invention;
fig. 2 is a control flow chart of an engine exhaust method according to a second embodiment of the present invention.
In the figure:
100. a main pipeline; 200. a bypass line; 300. an ECU;
201. a total air inlet; 202. bypassing the first branch; 203. bypassing the second branch; 204. a main gas outlet;
1. a supercharger; 2. a DOC; 3. a DPF; 4. SCR; 5. a first temperature sensor; 6. a second temperature sensor; 7. a first control valve; 8. a second control valve; 9. a third control valve; 10. a fourth control valve; 11. a fifth control valve; 12. and a sixth control valve.
Detailed Description
Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.
Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured" are to be construed broadly and encompass, for example, both fixed and removable connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Unless expressly stated or limited otherwise, the recitation of a first feature "on" or "under" a second feature may include the recitation of the first feature being in direct contact with the second feature, and may also include the recitation of the first feature being in contact with the second feature, but rather being in contact with the additional feature between them. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. "beneath," "under" and "beneath" a first feature includes the first feature being directly beneath and obliquely beneath the second feature, or simply indicating that the first feature is at a lower level than the second feature.
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
When the engine is started, the exhaust temperature is low, the DOC catalyst is inactivated, the DOC cannot play an oxidation role, but the DOC carrier can absorb a large amount of heat in exhaust gas, so that the SCR temperature rises slowly, urea cannot be injected (the urea injection temperature is not reached) or the conversion efficiency of the injected urea is very low (the SCR conversion efficiency is low at low temperature), NO is lowxThere is a risk that the emission requirements are not met. When the exhaust temperature is high during engine operation, DOC aging quickly results in reduced oxidation efficiency.
Due to NO in exhaust gas emissionxThe limit is very low, between 0.40g/kWh and 0.60 g/kWh. In order to satisfy this limit, the engine is required to be always in a region where the SCR conversion efficiency is high. The SCR conversion efficiency and the exhaust gas temperature have a very large relationship, and when the temperature is low, the SCR conversion efficiency is low, so that No in exhaust gas is causedxHigh content of (D). The invention can solve the problem of NO caused by low SCR conversion efficiencyxThe problem that emission requirements are not met exists, the DOC aging problem caused by high exhaust temperature is solved, and the service life of the DOC is prolonged.
Example one
As shown in fig. 1, the present embodiment provides an engine exhaust device, which includes a main pipe 100, a bypass pipe 200, a first temperature sensor 5, and a second temperature sensor 6, wherein a supercharger 1, a DOC2, a DPF3, and an SCR4 are sequentially connected in the main pipe 100, one end of the bypass pipe 200 is connected between the supercharger 1 and the DOC2, and the other end of the bypass pipe 200 can be communicated with an air inlet of the DPF 3. The first temperature sensor 5 is disposed between the supercharger 1 and the DOC2, and detects the temperature of the exhaust gas entering the DOC 2; a second temperature sensor 6 is disposed between DPF3 and SCR4 for sensing the temperature of the exhaust gas entering SCR 4. The outlet of the supercharger 1 can be selectively in communication with the inlet of the DOC2 or the bypass line 200.
In the engine exhaust device provided by the embodiment, one end of the bypass pipeline 200 is connected between the supercharger 1 and the DOC2, the other end of the bypass pipeline 200 can be communicated with the air inlet of the DPF3, and the air outlet of the supercharger 1 can be selectively communicated with the air inlet of the DOC2 or the bypass pipeline 200. The first temperature sensor 5 is used for detecting the temperature of the exhaust gas entering the DOC 2; the second temperature sensor 6 is used to detect the temperature of the exhaust gas entering the SCR 4. Through the control to the exhaust gas temperature who gets into DOC2 and the exhaust gas temperature who gets into SCR4, the discharge route of control waste gas had both avoided DOC2 to age the oxidation inefficiency that leads to fast, had guaranteed SCR 4's conversion efficiency again to make the emission of waste gas satisfy the demands.
It should be noted that the temperature upstream of SCR4 is substantially the same as the temperature of the exhaust gas entering SCR4, and when the temperature upstream of SCR4 is lower than the minimum temperature at which SCR4 can react sufficiently, the conversion efficiency of SCR4 is reduced, and NO in the exhaust gas of the diesel engine cannot be completely eliminatedx. In order to solve the problems of low temperature and slow temperature rise of the SCR4, optionally, the main pipeline 100 is further provided with a fifth control valve 11, and the fifth control valve 11 is disposed between the air outlet of the supercharger 1 and the air inlet of the DOC2, and is used for controlling whether the air outlet of the supercharger 1 is communicated with the air inlet of the DOC 2. When the temperature detected by the second temperature sensor 6 is lower than the lowest temperature at which the SCR4 can fully react, and the temperature detected by the first temperature sensor 5 is higher than the temperature detected by the second temperature sensor 6 (i.e. the temperature upstream of the DOC2 is higher than the temperature upstream of the SCR 4), the engine exhaust enters the DPF3 and the SCR4 through the bypass pipeline 200, so that the heat loss caused by the exhaust gas flowing through the DOC2 is reduced, and the time for raising the temperature of the SCR4 is shortened.
Optionally, the bypass line 200 comprises a total inlet 201 and a bypass first branch 202, the total inlet 201 is disposed between the supercharger 1 and the DOC2, an inlet of the bypass first branch 202 can be communicated with the total inlet 201, and an outlet of the bypass first branch 202 can be communicated with an inlet of the DPF 3. A first control valve 7 is arranged on the bypass first branch 202, and the first control valve 7 is used for controlling the on-off of the bypass first branch 202. When the temperature detected by the second temperature sensor 6 is lower than the lowest temperature at which the SCR4 can fully react, and the temperature detected by the first temperature sensor 5 is higher than the temperature detected by the second temperature sensor 6, the fifth control valve 11 is controlled to be closed, the first control valve 7 is controlled to be opened, and the exhaust gas from the supercharger 1 enters the bypass first branch 202, the DPF3 and the SCR4 through the main air inlet 201 and then is discharged to the atmosphere.
When the temperature of the upstream of the SCR4 is lower than the minimum temperature at which the SCR4 can fully react, and the temperature of the upstream of the DOC2 is lower than or equal to the temperature of the upstream of the SCR4, the temperature of the exhaust gas entering the SCR4 without passing through the DOC2 cannot reach the minimum temperature at which the SCR4 can fully react due to heat loss in a pipeline, and in order to avoid that the low-temperature exhaust gas cools the initial temperature inside the SCR4 after passing through the SCR4, which is not beneficial to the subsequent reaction of the SCR4, the low-temperature exhaust gas needs to be directly discharged through the DPF 3.
Optionally, the bypass line 200 further includes a bypass second branch 203 and a main outlet 204, an inlet of the bypass second branch 203 can be communicated with an outlet of the DPF3, an outlet of the bypass second branch 203 can be communicated with the main outlet 204, and the main outlet 204 is disposed downstream of the SCR4 and can be communicated with the atmosphere.
Optionally, a second control valve 8 is disposed on the bypass second branch 203, and the second control valve 8 is used to control on/off of the bypass second branch 203. A third control valve 9 is arranged between the air inlet of the bypass first branch 202 and the air outlet of the bypass second branch 203, and the third control valve 9 is used for controlling whether the main air inlet 201 and the air outlet of the bypass second branch 203 are communicated or not. The main pipeline 100 is provided with a fourth control valve 10, and the fourth control valve 10 is used for controlling whether the air outlet of the DPF3 is communicated with the air inlet of the SCR 4. The first control valve 7 and the second control valve 8 are controlled to be opened, the fourth control valve 10 and the fifth control valve 11 are controlled to be closed, and the exhaust gas from the supercharger 1 is discharged to the atmosphere through the main air inlet 201, the bypass first branch 202, the DPF3, the bypass second branch 203 and the main air outlet 204.
Preferably, the main pipeline 100 is further provided with a sixth control valve 12, and the sixth control valve 12 is used for controlling whether the outlet of the DOC2 is communicated with the inlet of the bypass first branch 202 or not and whether the outlet of the DOC2 is communicated with the inlet of the DPF3 or not. The sixth control valve 12 is arranged to prevent the exhaust gas from entering the DOC2 from the outlet of the bypass first branch 202, and to reduce the flow rate of the exhaust gas entering the DPF 3.
Preferably, the fourth control valve 10 is disposed between the intake of the bypass second branch 203 and the intake of the SCR 4. With such an arrangement, the fourth control valve 10 can control whether the outlet of the DPF3 is communicated with the inlet of the SCR4, and does not affect the communication between the outlet of the DPF3 and the inlet of the bypass second branch 203.
When the temperature detected by the second temperature sensor 6 is lower than the lowest temperature at which the SCR4 can react sufficiently and the temperature detected by the first temperature sensor 5 is lower than or equal to the temperature detected by the second temperature sensor 6, the first control valve 7 and the second control valve 8 are controlled to be opened and the third control valve 9, the fourth control valve 10, the fifth control valve 11, and the sixth control valve 12 are controlled to be closed. Exhaust gas from the supercharger 1 is exhausted to the atmosphere via the main inlet 201, the bypass first branch 202, the DPF3, the bypass second branch 203, and the main outlet 204.
When the temperature detected by the first temperature sensor 5 is higher than or equal to the minimum temperature that can degrade the DOC2, the first control valve 7 and the fourth control valve 10 are controlled to be opened, the second control valve 8, the third control valve 9, the fifth control valve 11, and the sixth control valve 12 are controlled to be closed, and the exhaust gas from the supercharger 1 is discharged to the atmosphere through the total intake port 201, the bypass first branch 202, the DPF3, and the SCR 4. Not only can prevent the DOC2 from aging, but also can ensure the conversion efficiency of the SCR 4. Since the lowest temperature at which DOC2 ages is much higher than the lowest temperature at which SCR4 can react sufficiently, when the temperature detected by first temperature sensor 5 is higher than or equal to the lowest temperature at which DOC2 can age, the conversion rate of SCR4 is not reduced regardless of whether the temperature detected by second temperature sensor 6 is higher than the lowest temperature at which SCR4 can react sufficiently.
In this embodiment, the engine is in a tow-back condition when the engine is running and the throttle is not open. When the engine is in a reverse-dragging working condition, the third control valve 9 is controlled to be opened, the first control valve 7, the second control valve 8, the fourth control valve 10, the fifth control valve 11 and the sixth control valve 12 are controlled to be closed, and exhaust gas from the supercharger 1 is discharged into the atmosphere through a main air inlet 201 and a main air outlet 204 of a bypass pipeline 200.
In the present embodiment, the engine exhaust device is controlled by an ECU (Electronic Control Unit) 300 of the engine, the first Control valve 7, the second Control valve 8, the third Control valve 9, the fourth Control valve 10, the fifth Control valve 11, and the sixth Control valve 12 are all electromagnetic valves, and the ECU300 is electrically connected to the first Control valve 7, the second Control valve 8, the third Control valve 9, the fourth Control valve 10, the fifth Control valve 11, the sixth Control valve 12, the first temperature sensor 5, and the second temperature sensor 6. The opening and closing of the first control valve 7, the second control valve 8, the third control valve 9, the fourth control valve 10, the fifth control valve 11, and the sixth control valve 12 are controlled by the ECU 300. The temperature values detected by the first temperature sensor 5 and the second temperature sensor 6 are transmitted to the ECU300, and the ECU300 stores a minimum temperature value at which the DOC2 is aged, a minimum temperature value at which the SCR4 can sufficiently react, and a setting program. After receiving the temperature values sent by the first temperature sensor 5 and the second temperature sensor 6, the ECU300 can compare the temperature values according to a set program, and control the opening and closing of the first control valve 7, the second control valve 8, the third control valve 9, the fourth control valve 10, the fifth control valve 11, and the sixth control valve 12 according to the comparison result. It should be noted that, the electrical connection and control principle between the ECU300 and the first control valve 7, the second control valve 8, the third control valve 9, the fourth control valve 10, the fifth control valve 11, the sixth control valve 12, the first temperature sensor 5 and the second temperature sensor 6 are all the prior art, and are not described herein again.
Example two
The embodiment provides an engine exhaust method, which is applied to an engine exhaust device provided by the first embodiment, the engine exhaust device comprises a main pipeline 100, a bypass pipeline 200, a first temperature sensor 5 and a second temperature sensor 6, a supercharger 1, a fifth control valve 11, a DOC2, a sixth control valve 12, a DPF3, a fourth control valve 10 and a SCR4 are sequentially connected in the main pipeline 100, the bypass pipeline 200 comprises a main air inlet 201, a bypass first branch 202, a third control valve 9, a bypass second branch 203 and a main air outlet 204, the bypass first branch 202 is provided with the first control valve 7, the bypass second branch 203 is provided with the second control valve 8, and the third control valve 9 is arranged between the bypass first branch 202 and the bypass second branch 203; the main air inlet 201 and the first temperature sensor 5 are both arranged between the supercharger 1 and the DOC2, the second temperature sensor 6 is arranged between the DPF3 and the SCR4, and the main air outlet 204 is arranged at the downstream of the SCR4 and can be communicated with the atmosphere.
The engine exhaust method provided by the embodiment comprises the following steps:
when the engine is in a reverse dragging working condition:
when the temperature detected by the second temperature sensor 5 is lower than the first preset temperature and the temperature detected by the first temperature sensor 5 is higher than the temperature detected by the second temperature sensor 6, exhaust gas is controlled to be discharged into the atmosphere through the supercharger 1, the total intake port 201, the bypass first branch 202, the DPF3, and the SCR 4.
When the temperature detected by the first temperature sensor 5 is higher than or equal to a second preset temperature, the first preset temperature is lower than the second preset temperature, and exhaust gas is controlled to be discharged into the atmosphere through the supercharger 1, the total air inlet 201, the bypass first branch 202, the DPF3 and the SCR 4.
In the engine exhaust method provided by the embodiment, when the temperature detected by the second temperature sensor 6 is lower than the first preset temperature, and the temperature detected by the first temperature sensor 5 is higher than the temperature detected by the second temperature sensor 6, that is, the temperature upstream of the SCR4 is lower than the first preset temperature, and the temperature upstream of the DOC2 is higher than the temperature upstream of the SCR4, in order to ensure the conversion efficiency of the SCR4, avoid the heat loss of the exhaust gas through the DOC2, and control the exhaust gas to be discharged to the atmosphere through the supercharger 1, the bypass first branch 202, the DPF3, and the SCR 4. In order to avoid the oxidation efficiency reduction caused by the high temperature increasing the aging speed of the DOC2, when the temperature detected by the first temperature sensor 5 is higher than or equal to the second preset temperature, and the first preset temperature is lower than the second preset temperature, the exhaust gas is also discharged into the atmosphere through the supercharger 1, the total air inlet 201, the bypass first branch 202, the DPF3 and the SCR 4. The engine exhaust method provided by the embodiment can reduce the aging speed of the DOC2 and ensure the conversion efficiency of the SCR 4.
Optionally, the first predetermined temperature is the lowest temperature at which the SCR4 can react sufficiently and the second predetermined temperature is the lowest temperature at which DO2C can age.
Alternatively, when the temperature detected by the second temperature sensor 6 is lower than a first preset temperature and the temperature detected by the first temperature sensor 5 is lower than or equal to the temperature detected by the second temperature sensor 6 under the non-reverse driving condition of the engine, the exhaust gas is controlled to be discharged into the atmosphere through the supercharger 1, the total air inlet 201, the bypass first branch 202, the DPF3, the bypass second branch 203 and the total air outlet 204.
Alternatively, exhaust gas is controlled to be discharged to the atmosphere through the supercharger 1, the total air inlet 201 and the total air outlet 204 when the engine is in a reverse-dragging condition.
In the present embodiment, the temperature detected by the first temperature sensor 5 is denoted as T1, the temperature detected by the second temperature sensor 6 is denoted as T2, the first preset temperature is denoted as T1, and the second preset temperature is denoted as T2.
As shown in fig. 2, the engine exhaust method provided by the embodiment includes the following steps:
and S1, starting the engine.
When the engine runs, the rotating speed is larger than zero, when the accelerator is not opened, the engine is in a back-dragging working condition, and when the accelerator is opened, the engine is in a non-back-dragging working condition.
And S2, judging whether the engine is in a back-dragging working condition (namely judging whether the accelerator is opened), if so, executing S31, and if not, executing S32.
And S31, controlling the third control valve 9 to be opened, closing the first control valve 7, the second control valve 8, the fourth control valve 10, the fifth control valve 11 and the sixth control valve 12, and discharging the waste gas into the atmosphere through the supercharger 1, the main gas inlet 201 and the main gas outlet 204.
Because the throttle is not opened and the fuel oil is not combusted, the waste gas almost has no pollutant and can be directly discharged into the atmosphere without being treated.
S32, judging whether the temperature T2 detected by the second temperature sensor 6 is lower than a first preset temperature T1 or not, if yes, executing S41; if not, S42 is executed.
In this embodiment, the first preset temperature t1 is the lowest temperature at which the SCR4 can fully react, and in order to ensure the conversion rate of the SCR4 and reduce the NOx emission, it is required to ensure that the temperature of the exhaust gas entering the SCR4 reaches the lowest temperature at which the SCR4 can fully react.
S41, it is determined whether the temperature T1 detected by the first temperature sensor 5 is higher than the temperature T2 detected by the second temperature sensor 6, if yes, S51 is executed, and if no, S52 is executed.
S51, the first control valve 7 and the fourth control valve 10 are controlled to open, the second control valve 8, the third control valve 9, the fifth control valve 11 and the sixth control valve 12 are controlled to close, and the exhaust gas is discharged to the atmosphere through the supercharger 1, the total intake port 201, the bypass first branch 202, the DPF3 and the SCR 4.
S52, the first control valve 7 and the second control valve 8 are controlled to be opened, and the third control valve 9, the fourth control valve 10, the fifth control valve 11 and the sixth control valve 12 are controlled to be closed. Exhaust gas is exhausted to the atmosphere via the supercharger 1, the total inlet 201, the bypass first branch 202, the DPF3, the bypass second branch 203 and the total outlet 204.
S42, determining whether the temperature T1 detected by the first temperature sensor 5 is higher than or equal to a second preset temperature T2, if yes, performing S51, otherwise, performing S61.
The first predetermined temperature t1 is lower than the second predetermined temperature t 2. Typically, the first preset temperature t1 is around 180 ℃ and the second preset temperature t2 is around 550 ℃.
S61, controlling the fifth control valve 11, the sixth control valve 12 and the fourth control valve 10 to be opened, closing the first control valve 7, the second control valve 8 and the third control valve 9, and discharging the exhaust gas into the atmosphere through the supercharger 1, the DOC2, the DPF3 and the SCR 4.
The above description is only a preferred embodiment of the present invention, and it should not be understood that the present invention is limited to the details of the embodiment and the range of applications, which can be changed by those skilled in the art according to the spirit of the present invention.

Claims (11)

1. An engine exhaust method is characterized in that an engine exhaust device comprises a main pipeline (100), a bypass pipeline (200), a first temperature sensor (5) and a second temperature sensor (6), wherein a supercharger (1), a DOC (2), a DPF (3) and an SCR (4) are sequentially connected in the main pipeline (100), the bypass pipeline (200) comprises a main air inlet (201), a bypass first branch (202), a bypass second branch (203) and a main air outlet (204), the main air inlet (201) and the first temperature sensor (5) are arranged between the supercharger (1) and the DOC (2), the second temperature sensor (6) is arranged between the DPF (3) and the SCR (4), and the main air outlet (204) is arranged at the downstream of the SCR (4) and can be communicated with the atmosphere; the engine exhaust method includes:
when the engine is in a non-reverse-dragging working condition:
when the temperature detected by the second temperature sensor (6) is lower than a first preset temperature, the first preset temperature is the lowest temperature at which the SCR (4) can fully react, and the temperature detected by the first temperature sensor (5) is higher than the temperature detected by the second temperature sensor (6), controlling the exhaust gas to be discharged into the atmosphere through the supercharger (1), the main air inlet (201), the bypass first branch (202), the DPF (3) and the SCR (4);
when the temperature that first temperature sensor (5) detected is higher than or equal to the second and predetermines the temperature, the second is predetermine the temperature and is for enabling DOC (2) ageing minimum temperature, first predetermined temperature is less than the second is predetermine the temperature, and the control waste gas is through booster (1) total air inlet (201) bypass first branch road (202) DPF (3) and SCR (4) discharge into the atmosphere.
2. The engine exhaust method according to claim 1, characterized in that, in the non-reverse-drive condition of the engine, when the temperature detected by the second temperature sensor (6) is lower than the first preset temperature and the temperature detected by the first temperature sensor (5) is lower than or equal to the temperature detected by the second temperature sensor (6), the exhaust gas is controlled to be exhausted to the atmosphere through the supercharger (1), the main air inlet (201), the bypass first branch (202), the DPF (3), the bypass second branch (203) and the main air outlet (204).
3. An engine exhaust method according to claim 1, characterized by controlling exhaust gases to be discharged to the atmosphere via the supercharger (1), the total inlet (201) and the total outlet (204) when the engine is in a tow-back condition.
4. An engine exhaust device characterized in that, with the engine exhaust method according to any one of claims 1 to 3, one end of the bypass line (200) is connected between the supercharger (1) and the DOC (2), and the other end of the bypass line (200) is communicable with an intake port of the DPF (3); the air outlet of the supercharger (1) can be selectively communicated with the air inlet of the DOC (2) or the bypass pipeline (200).
5. The engine exhaust arrangement according to claim 4, characterized in that the total inlet (201) is arranged between the supercharger (1) and the DOC (2), the inlet of the bypass first branch (202) being communicable with the total inlet (201), the outlet of the bypass first branch (202) being communicable with the inlet of the DPF (3).
6. The engine exhaust device according to claim 5, characterized in that a first control valve (7) is arranged on the bypass first branch (202), and the first control valve (7) is used for controlling the on-off of the bypass first branch (202).
7. The engine exhaust arrangement according to claim 5, characterized in that the inlet of the bypass second branch (203) can communicate with the outlet of the DPF (3), the outlet of the bypass second branch (203) can communicate with the total outlet (204), the total outlet (204) is arranged downstream of the SCR (4) and can communicate with the atmosphere.
8. The engine exhaust device according to claim 5, characterized in that a second control valve (8) is arranged on the bypass second branch (203), and the second control valve (8) is used for controlling the on-off of the bypass second branch (203); a third control valve (9) is arranged between the air inlet of the bypass first branch (202) and the air outlet of the bypass second branch (203), and the third control valve (9) is used for controlling whether the main air inlet (201) is communicated with the air outlet of the bypass second branch (203); the main pipeline (100) is further provided with a fourth control valve (10), and the fourth control valve (10) is used for controlling whether the air outlet of the DPF (3) is communicated with the air inlet of the SCR (4) or not.
9. Engine exhaust arrangement according to claim 8, characterized in that the fourth control valve (10) is arranged between the inlet of the bypass second branch (203) and the inlet of the SCR (4).
10. Engine exhaust arrangement according to claim 4, characterized in that the main pipe (100) is further provided with a fifth control valve (11), the fifth control valve (11) being arranged between the outlet of the supercharger (1) and the inlet of the DOC (2) for controlling whether the outlet of the supercharger (1) is in communication with the inlet of the DOC (2).
11. Engine exhaust according to claim 4, characterized in that the main line (100) is further provided with a sixth control valve (12), the sixth control valve (12) being adapted to control whether the outlet of the DOC (2) communicates with the inlet of the bypass first branch (202) and whether the outlet of the DOC (2) communicates with the inlet of the DPF (3).
CN202110450153.6A 2021-04-25 2021-04-25 Engine exhaust device and engine exhaust method Active CN113027577B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2414199A (en) * 2004-05-22 2005-11-23 Ford Global Tech Llc An exhaust system for an engine
JP2010209783A (en) * 2009-03-10 2010-09-24 Toyota Industries Corp Exhaust emission control device
CN204082275U (en) * 2014-08-29 2015-01-07 上海工程技术大学 A kind of diesel engine variable exhaust processing system
CN209687581U (en) * 2018-12-23 2019-11-26 周浩明 A kind of 6 discharge post-treatment system of automobile state
CN110878712A (en) * 2019-12-20 2020-03-13 潍柴动力股份有限公司 Post-treatment system and exhaust gas treatment method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2414199A (en) * 2004-05-22 2005-11-23 Ford Global Tech Llc An exhaust system for an engine
JP2010209783A (en) * 2009-03-10 2010-09-24 Toyota Industries Corp Exhaust emission control device
CN204082275U (en) * 2014-08-29 2015-01-07 上海工程技术大学 A kind of diesel engine variable exhaust processing system
CN209687581U (en) * 2018-12-23 2019-11-26 周浩明 A kind of 6 discharge post-treatment system of automobile state
CN110878712A (en) * 2019-12-20 2020-03-13 潍柴动力股份有限公司 Post-treatment system and exhaust gas treatment method

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