CN108301905B - Ammonia urea double-injection system and control method thereof - Google Patents
Ammonia urea double-injection system and control method thereof Download PDFInfo
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- CN108301905B CN108301905B CN201810181564.8A CN201810181564A CN108301905B CN 108301905 B CN108301905 B CN 108301905B CN 201810181564 A CN201810181564 A CN 201810181564A CN 108301905 B CN108301905 B CN 108301905B
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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
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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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
- 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
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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
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
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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
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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
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
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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
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
- F01N2610/146—Control thereof, e.g. control of injectors or injection valves
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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
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/14—Arrangements for the supply of substances, e.g. conduits
- F01N2610/1486—Means to prevent the substance from freezing
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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
- F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
- F01N2900/06—Parameters used for exhaust control or diagnosing
- F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
- F01N2900/1404—Exhaust gas temperature
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- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- 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
- Y02T10/12—Improving ICE efficiencies
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- 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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- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
The invention discloses an ammonia and urea dual-injection system which comprises a urea box, a urea pump, a urea nozzle, an ammonia storage tank, an ammonia metering valve, an ammonia nozzle, an ECU and a post-processor. The ammonia urea double-injection system provided by the invention mainly adopts urea injection, and the ammonia injection is only carried out under special working conditions such as cold start, low exhaust temperature, urea icing or ultrahigh SCR conversion efficiency, so that the problems of low exhaust temperature, low conversion efficiency and easy crystallization blockage of a national six-urea system under cold start working conditions can be solved; the problem that the discharge cannot be met rapidly because the cold region of the Guohu urea injection system needs to be thawed firstly when working is solved; the problem that the conversion efficiency of the six SCR is 99% is difficult to realize can be solved; and solves the problem of inconvenient popularization and use of the ammonia injection system.
Description
Technical Field
The invention relates to an ammonia urea dual-injection system and a control method thereof. The method is applied to the field of diesel engine tail gas aftertreatment.
Background
With the implementation of the national four-emission regulations of commercial vehicles, the whole vehicle must be additionally provided with a nitrogen oxide (NOx) emission treatment device.
The China medium and heavy duty diesel engine generally adopts a Selective Catalytic Reduction (SCR) technical route, namely, standard urea aqueous solution for vehicles is sprayed into exhaust gas, and ammonia generated by decomposition of the standard urea aqueous solution is used for carrying out selective catalytic reduction on NOx to generate harmless nitrogen and water.
The state announces that six national emissions regulations will be implemented in 2020, the NOx emission limits are greatly reduced, and at the same time strict regulations are being made on NOx emissions during cold start and low engine temperature conditions. The problem that urea is hydrolyzed and not supplemented to crystallize is extremely easy to occur when the exhaust temperature is lower than 200 ℃ under the influence of the characteristic of urea. The problems of crystallization, exceeding discharge and the like of the post-processor can be caused. Whereas urea freezes at-11 c, so that it is not possible to meet emission limits when the vehicle is operating at-11 c. Meanwhile, in order to reduce the oil consumption of an engine, the industry is started to trend to have no EGR scheme, and the SCR is only adopted to reduce NOx, so that the SCR conversion efficiency is required to be more than 99%, and the conventional urea injection system is difficult to achieve the aim.
Therefore, the industry generally starts to develop an ammonia injection system, and the problem of crystallization and icing of a urea system can be thoroughly avoided by directly injecting ammonia. The method for metering ammonia gas in a solid ammonia storage system according to document 1 (CN 103541796 a) is characterized by the following specific steps: 1) The working condition signal of the engine is sent by the ECU, and the DCU is instructed to change the opening degree of the electromagnetic valve according to the temperature output signal of the system; controlling the ammonia in the solid ammonia storage material to be uniformly output; 2) When the DCU obtains the input of the analog signal, and when the pressure sensor displays that the internal pressure is more than 200kPa, and when the temperature sensor displays that the internal temperature is more than 60 ℃, the electromagnetic valve is started; the combined use of the temperature sensor, the pressure sensor, the filter, the pressure stabilizing valve and the electromagnetic valve is suitable for SCR used in the emission standard of China 4 and above, and is also suitable for the future FCEV technology.
In patent document 2 (CN 202673414U), an exhaust pipe of an engine is divided into two paths a and b in parallel, an ammonia storage system is installed on a pipeline of one path, active ammonia storage compounds are heated by using a waste heat mode to release ammonia, and the ammonia is led into the front end of an SCR post-processor by a control unit according to the exhaust working condition level of the engine, so that an SCR system without liquid urea delivery injection and atomization decomposition is realized; the system has the characteristics of flexibility, low cost, high reliability and convenient use, and can meet the emission control target during low-temperature cold start of the vehicle; the system is suitable for systems above 4 of light diesel vehicles and medium diesel vehicles SCR, can be also applied to FCEV systems, meets the application requirements of future automobile industry, and has practical value.
Patent document 3 (CN 202673413U) relates to an exhaust pipe waste heat type ammonia storage and supply system, which is characterized in that: the outer flange plate is sleeved on the exhaust pipe, one side of the inner wall cylinder of the pressure-resistant tank is sleeved on the exhaust pipe and is fixedly connected with the outer flange plate, the other side of the inner wall cylinder of the pressure-resistant tank is fixedly connected with the other outer flange plate, the inner flange plate is sleeved on one side of the inner flange plate and is fixedly connected with the inner flange plate, the other side of the outer wall cylinder of the pressure-resistant tank is fixedly connected with the other inner flange plate, the two inner flange plates, the inner wall cylinder of the pressure-resistant tank and the outer wall cylinder of the pressure-resistant tank form a cavity, solid ammonia storage materials are filled in the cavity, the sensing end of the temperature sensor of the pressure-resistant tank is inserted into the solid ammonia storage materials and is connected onto the outer wall cylinder of the pressure-resistant tank, the control end of the electronic control unit is connected with the precise proportional valve through a signal wire, the air inlet pipe is connected with the air inlet end of the SCR post-processor, and the air outlet end of the SCR post-processor is connected with the exhaust pipe; the waste heat of the exhaust gas of the engine is heated, and the dosage of ammonia is conveyed and conveniently guided into the SCR aftertreatment system by means of the control unit and a group of electromagnetic valves or proportional valves, so that NOx is removed.
For the systems disclosed in patent document 1, patent document 2 and patent document 3, an ammonia adsorption technology is adopted, ammonia belongs to a hazardous chemical substance, filling and storing of an ammonia tank are required to be qualified to a certain extent, and the scarcity of a filling station of the ammonia tank brings great inconvenience to users, so that the urea injection system cannot be completely replaced and popularized comprehensively.
Disclosure of Invention
The invention aims to provide an ammonia urea dual-injection system and a control method thereof, which thoroughly solve the problems of low temperature discharge, low conversion efficiency and easy crystallization blockage of a Guohu urea system under a cold starting working condition.
The invention solves the technical problems by adopting the following technical scheme: an ammonia urea dual-injection system comprises a urea box, a urea pump, a urea nozzle, an ammonia storage tank, an ammonia metering valve, an ammonia nozzle, an ECU and a post-processor;
the inlet of the urea pump is communicated with the urea box, the outlet of the urea pump is connected with the urea nozzle, and the urea nozzle is arranged on the post-processor and is used for injecting urea liquid into the post-processor;
the ammonia storage tank is communicated with an ammonia nozzle through an ammonia metering valve, and the ammonia nozzle is arranged on the post-processor and is used for spraying ammonia into the post-processor;
the ECU is connected with the urea nozzle and used for controlling the injection of the urea nozzle; and the ECU is also connected with an ammonia gas metering valve and used for controlling the ammonia gas metering valve to spray the metered ammonia gas into the post-processor through the ammonia gas nozzle.
Optionally, the ammonia urea dual-injection system further comprises a temperature discharge sensor, wherein the temperature discharge sensor is installed on the post-processor and connected with the ECU, and is used for outputting the temperature of the gas in the current post-processor to the ECU.
Optionally, the ammonia urea dual-injection system further comprises an ambient temperature sensor, wherein the ambient temperature sensor is connected with the ECU and is used for outputting the ambient temperature of the current vehicle to the ECU.
Optionally, the ammonia urea dual-injection system further comprises a urea temperature sensor, wherein the urea temperature sensor is connected with the ECU and is used for outputting the current urea temperature in the urea box to the ECU.
Optionally, the ammonia urea dual-injection system further comprises a urea liquid level sensor, wherein the urea liquid level sensor is connected with the ECU and is used for outputting the liquid level of the current urea liquid of the urea box and sending the liquid level to the ECU.
Optionally, the ammonia urea dual-injection system further comprises a urea heating water valve and an ammonia storage tank heater, wherein the urea heating water valve is in signal connection with the ECU and is arranged on a urea heating water path, the urea heating water path is used for heating urea liquid in a urea tank, the ammonia storage tank heater is connected with the ECU, and the ammonia storage tank is heated under the control of the ECU.
The invention solves the technical problems by adopting the following technical scheme: a control method of an ammonia urea dual injection system, comprising:
s10, detecting the temperature of gas in the post-processor through a temperature discharge sensor, controlling an ammonia storage tank heater to be started to heat the ammonia storage tank by an ECU when the temperature of the gas in the post-processor is lower than a certain threshold value, controlling an ammonia metering valve to meter and spray ammonia, and detecting the temperature of urea liquid stored in a urea box; otherwise, executing step S30;
s20, when the temperature of the urea solution stored in the urea box is greater than or equal to minus 5 ℃, controlling the urea pump to build pressure and the urea nozzle not to spray, detecting the temperature of the gas in the post-processor, and when the temperature of the gas in the post-processor is higher than the threshold value, closing an ammonia metering valve, and controlling the urea nozzle to start spraying urea by the ECU according to the engine calibration data; when the temperature of the urea solution stored in the urea box is lower than-5 ℃, the ECU controls the urea heating water valve to be opened, and enables the temperature of the urea solution stored in the urea box to be between-5 ℃ and 5 ℃, and S20 is executed again;
s30, detecting the temperature of urea solution stored in the urea box, and when the temperature of the urea solution stored in the urea box is more than or equal to minus 5 ℃, closing an ammonia metering valve, and controlling a urea nozzle to open and spray urea by an ECU according to engine calibration data; when the temperature of the urea solution stored in the urea box is lower than-5 ℃, the ECU controls the urea heating water valve to be opened, and after the temperature of the urea solution stored in the urea box is between-5 ℃ and 5 ℃, the ammonia metering valve is closed, and the ECU controls the urea nozzle to open and spray urea according to the calibration data of the engine;
and when the SCR conversion efficiency is higher than 95%, the ECU controls the ammonia metering valve and the urea nozzle to be opened simultaneously.
Optionally, when the urea liquid level is lower than 2%, the ECU controls the urea nozzle to stop spraying urea and gives an alarm to the user to prompt that the urea is consumed; while controlling ammonia injection.
The invention has the following beneficial effects: the ammonia urea double-injection system provided by the invention mainly adopts urea injection, and the ammonia injection is only carried out under special working conditions such as cold start, low exhaust temperature, urea icing or ultrahigh SCR conversion efficiency, so that the problems of low exhaust temperature, low conversion efficiency and easy crystallization blockage of a national six-urea system under cold start working conditions can be solved; the problem that the discharge cannot be met rapidly because the cold region of the Guohu urea injection system needs to be thawed firstly when working is solved; the problem that the conversion efficiency of the six SCR is 99% is difficult to realize can be solved; and solves the problem of inconvenient popularization and use of the ammonia injection system.
Drawings
FIG. 1 is a schematic diagram of an ammonia urea dual injection system of the present invention;
the labels in the figures are: 1-a urea tank; 2-urea pump; 3-urea nozzle; 4-an ammonia storage tank; 5-an ammonia metering valve; 6-ammonia gas nozzle; 7-ECU; an 8-post processor; 9-a temperature discharge sensor; 10-an ambient temperature sensor; 11-urea temperature sensor; 12-urea heating water valve; 13-urea level sensor; 14-ammonia storage tank heater.
Detailed Description
The technical scheme of the invention is further described below with reference to the embodiment and the attached drawings.
Example 1
The embodiment provides an ammonia and urea dual-injection system, which comprises a urea box 1, a urea pump 2, a urea nozzle 3, an ammonia storage tank 4, an ammonia metering valve 5, an ammonia nozzle 6, an ECU7, a post-processor 8, a temperature discharge sensor 9, an environment temperature sensor 10, a urea temperature sensor 11, a urea heating water valve 12, a urea liquid level sensor 13 and an ammonia storage tank heater 14.
The urea tank 1 stores standard vehicle urea solution, the urea pump 2 pumps the urea solution to the urea nozzle 3 in a pressurized mode, and the ECU7 controls the urea nozzle 3 to spray the atomized urea solution into the post-processor 8 for reaction.
That is, the inlet of the urea pump 2 is communicated with the urea tank 1, the outlet of the urea pump is connected to the urea nozzle 3, and the urea nozzle 3 is mounted on the post-processor 8 for injecting urea solution into the post-processor 8.
The ammonia storage tank 4 stores liquid ammonia or adsorbs ammonia, and the ECU7 controls the ammonia storage tank heater 14 to heat the ammonia storage tank 4 by exhaust gas or electric heating to release ammonia. The ECU7 controls the ammonia metering valve 5 to inject the metered ammonia gas from the ammonia gas nozzle 6 into the post-processor 8.
That is, the ammonia storage tank 4 is communicated with an ammonia gas nozzle 6 through an ammonia gas metering valve 5, and the ammonia gas nozzle 6 is mounted on the post-processor 8 for injecting ammonia gas into the post-processor 8.
A temperature exhaust sensor 9 is installed on the post-processor 8 and is used for outputting the temperature of the gas in the post-processor 8; the ambient temperature sensor 10 is used for outputting the current ambient temperature of the vehicle; the urea temperature sensor 11 is used for outputting the current urea temperature in the urea tank, and the urea liquid level sensor 13 is used for outputting the current urea liquid level in the urea tank.
And, the exhaust temperature sensor 9, the ambient temperature sensor 10, the urea temperature sensor 11 and the urea level sensor 13 are all signal-connected to the ECU7 to transmit the signals detected by them to the ECU7.
The ammonia urea dual-injection system further comprises a urea heating water channel, the urea heating water channel is used for heating urea liquid in the urea box 1, the urea liquid in the urea box 1 is prevented from being excessively low in temperature, the urea heating water channel is provided with a urea heating water valve 12, the urea heating water valve 12 is opened and closed through ECU control, when the urea heating water valve 12 is opened, the urea heating water channel is communicated, the urea liquid is heated, and when the urea heating water valve 12 is closed, the urea heating water channel is closed, and the urea liquid is stopped being heated.
The ammonia urea double-injection system provided by the invention mainly adopts urea injection, and the ammonia injection is only carried out under special working conditions such as cold start, low exhaust temperature, urea icing or ultrahigh SCR conversion efficiency, so that the problems of low exhaust temperature, low conversion efficiency and easy crystallization blockage of a national six-urea system under cold start working conditions can be solved; the problem that the discharge cannot be met rapidly because the cold region of the Guohu urea injection system needs to be thawed firstly when working is solved; the problem that the conversion efficiency of the six SCR is 99% is difficult to realize can be solved; and solves the problem of inconvenient popularization and use of the ammonia injection system.
Example 2
The embodiment provides a control method of an ammonia urea dual-injection system, which comprises the following steps:
s10, detecting the temperature of the gas in the post-processor 8 through the exhaust temperature sensor 7, and when the temperature of the gas in the post-processor 8 is lower than a certain threshold (200 ℃), controlling the ammonia storage tank heater 14 to open so as to heat the ammonia storage tank 4 and controlling the ammonia metering valve 5 to meter and spray ammonia by the ECU7.
When the vehicle is cold started, the temperature in the post processor 8 is low, and at the moment, if urea is injected, the problems of crystallization and low conversion efficiency are easy to occur. The ammonia metering valve 5 is controlled by the ECU7 to spray ammonia, so that the nitrogen oxide emission of the diesel vehicle can be reduced by the ammonia.
And S20, when the temperature of the urea solution stored in the urea box 1 is higher than-5 ℃, controlling the urea pump 2 to build pressure and controlling the urea nozzle 3 not to spray until the exhaust temperature rises to more than 200 ℃, closing the ammonia metering valve 5, and controlling the urea nozzle 3 to start spraying urea by the ECU7 according to the engine calibration data.
S30, if the temperature of the urea is lower than-5 ℃, controlling the urea heating water valve 12 to be opened, and after the temperature of the urea is raised to 5 ℃, controlling the urea heating water valve to be closed, at the moment, controlling the urea pump 2 to build pressure without jetting the urea nozzle 3, and controlling the urea heating water valve 12 to be opened and closed to keep the temperature of the urea between-5 ℃ and 5 ℃. After the exhaust temperature is increased to more than 200 ℃, the ammonia metering valve 5 is closed, and the ECU7 controls the urea nozzle 3 to open and spray urea according to the engine calibration data.
S40, in the running process of the vehicle, when the exhaust temperature is lower than 200 ℃, ammonia gas is injected without urea injection, and when the exhaust temperature is higher than 200 ℃ and the SCR conversion efficiency is not higher than 95%, urea is injected without ammonia gas injection.
S50, when the SCR conversion efficiency is higher than 95%, 95% of NOx is converted by urea, and more than 95% of NOx is reacted by ammonia. At this time, the ECU7 controls the ammonia metering valve 5 to be opened simultaneously with the urea nozzle 3. Since the ammonia gas expands to absorb heat after being injected, the urea nozzle 3 is optimally arranged at the front end of the ammonia gas metering valve 5 so as to ensure the optimal decomposition environment of urea. Through mixed injection, the optimal distribution uniformity of ammonia in the post-processor can be realized, so that the conversion efficiency is improved.
And S60, when the urea liquid level is lower than 2%, the ECU7 controls the urea nozzle 3 to stop spraying urea, and gives an alarm to the user to prompt that the urea is consumed. And meanwhile, ammonia injection is controlled to avoid exceeding the standard of vehicle emission.
The sequence of the above embodiments is only for convenience of description, and does not represent the advantages and disadvantages of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (4)
1. The control method of the ammonia urea double-injection system is characterized by being used for controlling the ammonia urea double-injection system, wherein the ammonia urea double-injection system comprises a urea box, a urea pump, a urea nozzle, an ammonia storage tank, an ammonia metering valve, an ammonia nozzle, an ECU, a post-processor, a temperature discharge sensor, a urea temperature sensor, a urea heating water valve and an ammonia storage tank heater;
the inlet of the urea pump is communicated with the urea box, the outlet of the urea pump is connected with the urea nozzle, and the urea nozzle is arranged on the post-processor and is used for injecting urea liquid into the post-processor;
the ammonia storage tank is communicated with an ammonia nozzle through an ammonia metering valve, and the ammonia nozzle is arranged on the post-processor and is used for spraying ammonia into the post-processor;
the ECU is connected with the urea nozzle and used for controlling the injection of the urea nozzle; the ECU is also connected with an ammonia gas metering valve and is used for controlling the ammonia gas metering valve to spray the metered ammonia gas into the post-processor through an ammonia gas nozzle;
the exhaust temperature sensor is arranged on the post-processor and connected with the ECU, and is used for outputting the temperature of the gas in the current post-processor to the ECU;
the urea temperature sensor is connected with the ECU and is used for outputting the current urea temperature in the urea box to the ECU;
the urea heating water valve is in signal connection with the ECU and is arranged on the urea heating water path, the urea heating water path is used for heating urea liquid in the urea box, the ammonia storage tank heater is connected with the ECU, and the ammonia storage tank is heated under the control of the ECU;
the control method of the ammonia urea dual-injection system comprises the following steps:
s10, detecting the temperature of gas in the post-processor through a temperature discharge sensor, controlling an ammonia storage tank heater to be started to heat the ammonia storage tank by an ECU when the temperature of the gas in the post-processor is lower than a certain threshold value, controlling an ammonia metering valve to meter and spray ammonia, and detecting the temperature of urea liquid stored in a urea box; otherwise, executing step S30;
s20, when the temperature of the urea solution stored in the urea box is greater than or equal to minus 5 ℃, controlling the urea pump to build pressure and the urea nozzle not to spray, detecting the temperature of the gas in the post-processor, and when the temperature of the gas in the post-processor is higher than the threshold value, closing an ammonia metering valve, and controlling the urea nozzle to start spraying urea by the ECU according to the engine calibration data; when the temperature of the urea solution stored in the urea box is lower than-5 ℃, the ECU controls the urea heating water valve to be opened, and enables the temperature of the urea solution stored in the urea box to be between-5 ℃ and 5 ℃, and S20 is executed again;
s30, detecting the temperature of urea solution stored in the urea box, and when the temperature of the urea solution stored in the urea box is more than or equal to minus 5 ℃, closing an ammonia metering valve, and controlling a urea nozzle to open and spray urea by an ECU according to engine calibration data; when the temperature of the urea solution stored in the urea box is lower than-5 ℃, the ECU controls the urea heating water valve to be opened, and after the temperature of the urea solution stored in the urea box is between-5 ℃ and 5 ℃, the ammonia metering valve is closed, and the ECU controls the urea nozzle to open and spray urea according to the calibration data of the engine;
and when the SCR conversion efficiency is higher than 95%, the ECU controls the ammonia metering valve and the urea nozzle to be opened simultaneously.
2. The method for controlling an ammonia urea dual injection system according to claim 1, wherein when the urea level is lower than 2%, the ECU controls the urea nozzle to stop injecting urea and gives an alarm to the user that urea is consumed; while controlling ammonia injection.
3. The method for controlling an ammonia urea dual injection system according to claim 1, further comprising an ambient temperature sensor connected to the ECU for outputting the current ambient temperature of the vehicle to the ECU.
4. A control method of an ammonia urea dual injection system according to claim 3, further comprising a urea level sensor connected to the ECU for outputting the level of the current urea solution of the urea tank to the ECU.
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| CN114165315A (en) * | 2021-12-07 | 2022-03-11 | 中船动力(集团)有限公司 | Reducing agent evaporation mixing system of SCR (selective catalytic reduction) system of marine diesel engine and supply method |
| CN116398277B (en) * | 2023-03-27 | 2024-06-07 | 一汽解放汽车有限公司 | Ammonia gas injection control method, device, system and storage medium |
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