CN114483267B - Supply device and control method for SCR (selective catalytic reduction) dual-injection urea for vehicle - Google Patents
Supply device and control method for SCR (selective catalytic reduction) dual-injection urea for vehicle Download PDFInfo
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- CN114483267B CN114483267B CN202210167770.XA CN202210167770A CN114483267B CN 114483267 B CN114483267 B CN 114483267B CN 202210167770 A CN202210167770 A CN 202210167770A CN 114483267 B CN114483267 B CN 114483267B
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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]
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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
- 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
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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
- F01N2610/1426—Filtration means
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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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- 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
Abstract
The invention provides a supply device and a control method of SCR (selective catalytic reduction) dual-injection urea for a vehicle, wherein the supply device comprises a urea tank, an air inlet valve, an exhaust valve and a pressure sensor of the urea tank are arranged on the urea tank, a first filtering piece and a second filtering piece are arranged in the urea tank, a cooling liquid heating pipeline and a urea liquid level sensor are inserted into the urea tank, and the supply device is operated by a controller. According to the invention, through designing the SCR double-injection urea supply device and the control method, the purposes of independently controlling the urea metering supply of each stage of SCR, reducing the system complexity and reducing the cost and the vehicle servicing quality are achieved, the requirement of national seven-stage SCR double-injection urea supply is met, and compared with the national six-gas-drive urea system, the SCR double-injection urea supply device has the advantages of higher injection precision, more accurate fault diagnosis of urea flow deviation, metering valve blockage and the like.
Description
Technical Field
The invention belongs to the technical field of diesel engine control, relates to the field of diesel engine aftertreatment emission control, and particularly relates to a supply device and a control method of SCR dual-injection urea for a vehicle.
Background
With the gradual implementation of the emission regulation GB17691-2018, the mobile source atmospheric pollutants are effectively controlled, but the mobile source pollutant control is not at the end, and the space for further reduction is provided. At this stage, the DOC + DPF + SCR + ASC technical route is commonly adopted by various domestic host plants to meet the regulation requirements, namely the scheme of a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction device and an ammonia oxidation catalyst. In order to meet the requirements of the future emission regulations, the selective catalytic reduction device is developed and upgraded into a coupling selective catalytic reduction device, a coupling diesel oxidation device, a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction device and an ammonia oxidation catalyst.
CN108301905A discloses an ammonia urea dual injection system, which includes a urea tank, 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 dual-injection system provided by the invention mainly injects urea, and ammonia injection is only carried out under special working conditions of cold start, low exhaust temperature, urea icing or ultra-high SCR conversion efficiency, so that the problems of low conversion efficiency and easy crystallization blockage of the national urea system under the working conditions of low exhaust temperature and cold start can be solved; the problem that the cold region of a national urea injection system needs to be unfrozen firstly when working, and the emission cannot be met quickly is solved; the problem that the conversion efficiency of the national six SCR is difficult to realize at 99 percent can be solved; and the problem that the ammonia gas injection system is inconvenient to popularize and use is solved.
CN206554996U discloses a double-pressure sensor type gas drive urea injection system, which comprises a urea tank, a urea filter, an air source, a urea nozzle and a controller ECU; an air inlet valve and an exhaust valve are arranged on the urea tank, and an air path pressure sensor is arranged in the urea tank; the urea filter is respectively connected with the urea tank and the urea nozzle; a liquid path pressure sensor connected with the controller ECU is arranged between the urea filter and the urea nozzle; the liquid path pressure sensor comprises a control chip, a sensor joint, a heat conducting sheet and an electric heating urea tank. The utility model discloses a can carry out the gas circuit pressure sensor that detects and can carry out the liquid way pressure sensor that detects to injection pressure to system pressure, ECU realizes the accuracy control to the urea nozzle, to the accurate judgement of urea nozzle operating condition and realize the maintenance of urea filter according to the accurate timing of resistance through the comprehensive analysis to gas circuit pressure sensor and liquid way pressure sensor signal.
CN113669137A discloses a urea injection device, a urea injection system, and a urea injection control method, where the urea injection device includes a urea nozzle, a compressed air pipeline, and a heating device, an outlet of the urea nozzle is communicated with the compressed air pipeline, the heating device is disposed in the compressed air pipeline, and the heating device is used to heat compressed air in the compressed air pipeline or a mixture of the compressed air and urea spray; when cold start, heating device can heat the urea spraying to predetermineeing the temperature and carry out the vaporization decomposition before urea gets into exhaust pipe, it will be the mist of ammonia and air to get into exhaust pipe like this, can not produce the problem that urea crystallization and low temperature can't accomplish urea decomposition in exhaust pipe, can reduce the temperature that urea starts to spout like this, reduce to 150 ℃ by 200 ℃, can effectively reduce the nitrogen oxide emission under the low temperature, and can strictly control the temperature that urea aqueous solution decomposes through heating device, reduce the risk of urea crystallization.
At present, two sets of reducing agent supply devices are needed in the prior art, the structure is complex, the quality and the cost of the whole vehicle are increased, large-scale mass production application cannot be realized in the seventh stage of China, and the requirement of a post-treatment technical route for the seventh stage of China on a urea supply device cannot be met.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a supply device and a control method of SCR double-injection urea for a vehicle.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a supply device of SCR dual-injection urea for a vehicle, which comprises a urea tank, wherein an air inlet valve, an exhaust valve and a urea tank pressure sensor are arranged on the urea tank;
the urea tank is internally provided with a first filter element and a second filter element, the first filter element is sequentially and externally connected with a urea metering assembly through a urea pipeline, the urea metering assembly is connected with the front end of the coupling SCR, the second filter element is sequentially and externally connected with a coupling urea metering assembly through a coupling urea pipeline, and the coupling urea metering assembly is connected with the front end of the coupling SCR;
the urea tank is internally inserted with a cooling liquid heating pipeline and a urea liquid level sensor, the cooling liquid heating pipeline is externally connected with a heating element, and the supply device is operated through a controller.
According to the invention, by designing the SCR dual-injection urea supply device and the control method suitable for the SCR dual-injection technical route, the purposes of independently controlling the urea metering supply of each stage of SCR, reducing the complexity of the system, lowering the cost and the vehicle maintenance quality are achieved, and the supply requirement of SCR dual-injection urea in seven stages in China is met.
It should be noted that, in the invention, the feedback value of the pressure sensor of the urea metering valve can be used to replace the feedback value of the pressure sensor of the urea tank, so as to cancel the arrangement of the pressure sensor of the urea tank; or the feedback value of the urea metering valve pressure sensor is used for replacing the feedback value of the urea tank pressure sensor, so that the urea tank pressure sensor is not arranged; and after the urea pressure buildup process is finished, the supply device can realize that the two urea supply pipelines independently supply urea to the exhaust pipe, wherein when one urea supply pipeline has a fault, such as blockage of a metering valve, electrical fault and the like, the other urea supply pipeline can still normally work, and the robustness of the SCR system is improved.
In a preferred embodiment of the present invention, the intake valve is an intake solenoid valve, and the exhaust valve is an exhaust solenoid valve.
As a preferred technical solution of the present invention, the first filter element and the second filter element are both urea filter elements, which are a urea filter element i and a urea filter element ii, respectively.
As a preferable technical scheme, the urea metering assembly comprises a urea metering valve and a urea metering valve pressure sensor, and the in-coupling urea metering assembly comprises an in-coupling urea metering valve and an in-coupling urea metering valve pressure sensor.
As a preferred technical scheme of the invention, the heating element is a urea tank heating electromagnetic valve.
As a preferable technical solution of the present invention, the gas source is an air cylinder.
In a second aspect, the present invention provides a control method of the supply apparatus of the first aspect, the control method including:
(1) Detecting the ambient temperature and the temperature of the urea tank, and if the ambient temperature and the temperature of the urea tank are lower than temperature thresholds, heating the supply device, wherein the heating of the urea in the urea tank by the heating element is controlled, and meanwhile, the urea inlet pipeline and the urea inlet pipeline are heated;
(2) Ending the heating process in the step (1), if the pressure of the urea tank is lower than the preset pressure, opening an air inlet valve, allowing compressed air in a gas source to enter the urea tank, and closing the air inlet valve until the pressure of the urea tank reaches a target pressure;
(3) The controller respectively calculates and outputs the urea demand of the in-coupling SCR reaction and the SCR reaction through an SCR control module, and respectively sprays the required urea into the exhaust pipe for the vehicle according to the test data of the urea metering valve, the urea metering valve pressure sensor, the in-coupling urea metering valve and the in-coupling urea metering valve pressure sensor;
(4) When the vehicle engine is shut down, the exhaust valve is opened to reduce the pressure in the urea tank to the normal atmospheric pressure of 101.325kPa, and when the pressure in the urea tank reaches the pressure threshold value, the exhaust valve is closed.
In a preferred embodiment of the present invention, the temperature threshold is-7 to-5 ℃, and may be, for example, -7 ℃, -6.5 ℃, -6 ℃, -5.5 ℃, -5 ℃, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
The predetermined pressure is 650 to 670kPa, for example, 650kPa, 652kPa, 654kPa, 656kPa, 658kPa, 660kPa, 662kPa, 664kPa, 666kPa, 668kPa, 670kPa, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
The target pressure is 700 to 800kPa, and may be 700kPa, 710kPa, 720kPa, 730kPa, 740kPa, 750kPa, 760kPa, 770kPa, 780kPa, 790kPa, 800kPa, for example, but is not limited to the values listed, and other values not listed in the range of values are also applicable.
The pressure threshold value is 20 to 30kPa, and may be, for example, 20kPa, 21kPa, 22kPa, 23kPa, 24kPa, 25kPa, 26kPa, 27kPa, 28kPa, 29kPa, 30kPa, but is not limited to the values listed, and other values not listed in the range of the values are also applicable.
As a preferable technical scheme, whether the urea metering valve is blocked or not and whether the flow deviation fault exists or not can be judged through the urea demand and the test value of the pressure sensor of the urea metering valve.
As a preferable technical scheme, whether the inlet coupling urea metering valve is blocked or not and whether flow deviation faults exist or not can be judged through the urea demand and the test value of the inlet coupling urea metering valve pressure sensor.
The SCR dual-injection urea supply device of the present invention is mainly composed of four modules, namely, a urea tank pressure control module, a urea system heating module, a coupling urea supply module, and a urea supply module.
The urea tank pressure control module mainly comprises a urea tank, an air inlet valve, an exhaust valve and a urea tank pressure sensor. The urea tank pressure control process comprises pressure build control, injection control and emptying control.
The urea system heating module mainly comprises a cooling liquid heating pipeline, a urea liquid level sensor, a heating piece, a urea pipeline and a coupling urea pipeline, and the urea system heating function mainly comprises urea tank heating, urea pipeline heating and coupling urea pipeline heating.
The system mainly comprises a urea filter element II, a coupling urea pipeline, a coupling urea metering valve and a coupling urea metering valve pressure sensor, and the coupling urea supply function mainly comprises a coupling urea metering supply control function and urea filter element blockage diagnosis.
The urea supply module mainly comprises a first urea filter element, a urea pipeline, a urea metering valve and a urea metering valve pressure sensor, and the urea supply module mainly comprises a urea metering supply control function and a urea filter element blockage diagnosis function.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, by designing the SCR dual-injection urea supply device and the control method suitable for the SCR dual-injection technical route, the purposes of independently controlling the urea metering supply of each stage of SCR, reducing the complexity of the system, lowering the cost and the vehicle maintenance quality are achieved, and the supply requirement of SCR dual-injection urea in seven stages in China is met.
Drawings
FIG. 1 is a schematic diagram of a SCR dual injection urea delivery system according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of a urea tank pressure control process provided in an embodiment of the present invention;
FIG. 3 is a diagram of an algorithm for accurate urea metering according to an embodiment of the present invention;
wherein, 1-urea tank; 2-urea line; 3-a cooling liquid heating pipeline; 4-urea level sensor; 5-a urea filter element I; 6-a urea filter element II; 7-an air inlet valve; 8-heating element; 9-an exhaust valve; 10-urea tank pressure sensor; 11-inlet coupling urea pipeline; 12-an in-coupled urea metering valve; 13-in coupling urea metering valve pressure sensor; 14-a urea metering valve; 15-urea metering valve pressure sensor.
Detailed Description
It is to be understood that in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be taken as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate a number of the indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
It should be noted that, unless explicitly stated or limited otherwise, the terms "disposed," "connected" and "connected" in the description of the present invention are to be construed broadly and may include, for example, a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
It should be understood by those skilled in the art that the present invention necessarily includes necessary piping, conventional valves and general pump equipment for achieving the complete process, but the above contents do not belong to the main inventive points of the present invention, and those skilled in the art can select the layout of the additional equipment based on the process flow and the equipment structure, and the present invention is not particularly limited to this.
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
In a specific embodiment, the present invention provides a supply device of SCR dual-injection urea for a vehicle, as shown in fig. 1, the supply device includes a urea tank 1, an air inlet valve 7, an exhaust valve 9 and a urea tank pressure sensor 10 are disposed on the urea tank 1, an air inlet end of the air inlet valve 7 is connected to an air source phase, an air outlet end is connected to the urea tank 1, an air inlet end of the exhaust valve 9 is connected to the urea tank 1, an air outlet end is externally connected to atmosphere, a first filter member and a second filter member are disposed in the urea tank 1, the first filter member is sequentially externally connected to a urea metering assembly through a urea pipeline 2, the urea metering assembly is connected to a coupling SCR front end, the second filter member is sequentially externally connected to a coupling urea metering assembly through a coupling urea pipeline 11, the coupling urea metering assembly is connected to the coupling SCR front end, a cooling liquid heating pipeline 3 and a urea liquid level sensor 4 are inserted into the urea tank 1, the cooling liquid heating pipeline 3 has 8, and the supply device is operated by a controller.
According to the invention, by designing the SCR dual-injection urea supply device and the control method suitable for the SCR dual-injection technical route, the purposes of independently controlling the urea metering supply of each stage of SCR, reducing the complexity of the system, lowering the cost and the vehicle maintenance quality are achieved, and the supply requirement of SCR dual-injection urea in seven stages in China is met.
It should be noted that, in the present invention, the feedback value of the in-coupling urea metering valve pressure sensor 13 can be used to replace the feedback value of the urea tank pressure sensor 10, and thus the urea tank pressure sensor 10 is not provided; or the feedback value of the urea metering valve pressure sensor 15 is used for replacing the feedback value of the urea tank pressure sensor 10, so that the urea tank pressure sensor 10 is not arranged; and after the urea pressure building process is finished, the supply device can realize that the two urea supply pipelines independently supply urea to the exhaust pipe, when one urea supply pipeline has a fault, such as the blockage of a metering valve, the existence of an electrical fault and the like, the other urea supply pipeline can still normally work, and the robustness of the SCR system is improved.
Wherein, admission valve 7 is the solenoid valve that admits air, and discharge valve 9 is the solenoid valve that exhausts, and filter piece one and filter piece two and be the urea filter core, is urea filter core one 5 and two 6 of urea filter core respectively, and urea measurement subassembly includes urea metering valve 14 and urea metering valve pressure sensor 15, and the urea measurement subassembly that advances to couple includes into coupling urea metering valve 12 and advances coupling urea metering valve pressure sensor 13, and heating member 8 is 1 heating solenoid valve of urea jar, and the gas source is the gas receiver.
In another embodiment, the present invention provides a control method of a supply apparatus described in one embodiment, the control method including:
(1) Detecting the ambient temperature and the temperature of the urea tank 1, and if the ambient temperature and the temperature of the urea tank 1 are lower than temperature thresholds, heating the supply device, wherein the heating of the urea in the urea tank 1 by the heating element 8 is controlled, and meanwhile, the urea inlet pipeline 11 and the urea inlet pipeline 2 are heated;
(2) Ending the heating process in the step (1), if the pressure of the urea tank 1 is lower than the preset pressure, opening the air inlet valve 7, allowing the compressed air in the air source to enter the urea tank 1, and closing the air inlet valve 7 until the pressure of the urea tank 1 reaches the target pressure;
(3) The controller respectively calculates and outputs the required urea amount of the in-coupling SCR reaction and the SCR reaction through an SCR control module, and respectively sprays the required urea into the exhaust pipe for the vehicle according to the test data of the urea metering valve 14, the urea metering valve pressure sensor 15, the in-coupling urea metering valve 12 and the in-coupling urea metering valve pressure sensor 13;
(4) When the vehicle engine is shut down, the exhaust valve 9 is opened to reduce the pressure in the urea tank 1 to the normal atmospheric pressure of 101.325kPa, and when the pressure in the urea tank 1 reaches a pressure threshold value, the exhaust valve 9 is closed.
The temperature threshold value is-7 to-5 ℃, the preset pressure is 650 to 670kPa, the target pressure is 700 to 800kPa, the pressure threshold value is 20 to 30kPa, whether the urea metering valve 14 is blocked or not and flow deviation faults or not can be judged through the urea demand and the test value of the urea metering valve pressure sensor 15, and whether the urea metering valve 12 is blocked or not and flow deviation faults or not can be judged through the urea demand and the test value of the urea metering valve pressure sensor 13.
The SCR dual-injection urea supply device of the present invention is mainly composed of four modules, namely, a urea tank 1 pressure control module, a urea system heating module, a coupling urea supply module, and a urea supply module.
The pressure control module for the urea tank 1 mainly comprises the urea tank 1, an air inlet valve 7, an exhaust valve 9 and a urea tank pressure sensor 10. The urea tank 1 pressure control process comprises pressure build-up control, injection control and emptying control, as shown in fig. 2, which is as follows:
and (3) pressure building control: after the engine is started successfully, the controller firstly judges whether the pressure building condition of the urea system is met, after the condition is met, the air inlet valve 7 is opened, compressed air in the air storage cylinder of the whole vehicle enters the urea tank 1 through the air inlet electromagnetic valve, the gas pressure in the urea tank 1 is raised to a target pressure, and the urea pressure building process is completed.
And (3) injection control: the urea pressure change caused by the urea liquid level in the urea tank 1 is small, the pressure of the urea solution in the urea tank 1 is considered to be equal to the gas pressure detected by the urea tank pressure sensor 10, in the running process of the engine, as the urea in the tank is gradually supplied and sprayed into the exhaust pipe, the gas pressure detected by the urea tank pressure sensor 10 gradually decreases, when the gas pressure is lower than the lower limit Pb of the air pressure, usually Pb =670kPa, the controller drives the air inlet electromagnetic valve to open, the compressed air is supplemented into the urea tank 1, and when the air pressure exceeds the standard pressure 101.325kPa again, the air inlet electromagnetic valve is closed.
Emptying control: when the engine is stopped or the urea system is required to be emptied due to other reasons, the controller drives the exhaust valve 9 to be opened, the compressed air in the urea tank 1 enters the atmosphere external environment through the exhaust valve 9, when the gas pressure in the urea tank 1 is lower than an emptying completion pressure threshold Pc, usually Pc =20kPa, the exhaust valve 9 is closed, and the emptying process is completed.
To urea system heating module, it mainly includes coolant liquid heating pipeline 3, urea level sensor 4, heating member 8, urea pipeline 2 and advances coupling urea pipeline 11, and urea system heating function mainly includes 1 heating of urea jar, the heating of urea pipeline 2 and advances the heating of coupling urea pipeline 11, specifically as follows:
heating of the urea tank 1: when the engine is started, if the temperature of the urea detected by the temperature sensor in the urea liquid level sensor 4 is lower than a threshold value Ta, usually Ta = -7 ℃, the controller drives the heating part 8 to be opened, the engine coolant enters the coolant heating pipeline 3 through the heating part 8, and the urea in the urea tank 1 is unfrozen and heated in a heat preservation mode.
Aiming at the inlet coupling urea supply module, the inlet coupling urea supply module mainly comprises a second urea filter element 6, an inlet coupling urea pipeline 11, an inlet coupling urea metering valve 12 and an inlet coupling urea metering valve pressure sensor 13, wherein the inlet coupling urea supply function mainly comprises an inlet coupling urea metering supply control function and urea filter element blockage diagnosis, and the inlet coupling urea supply module specifically comprises the following steps:
in-coupling urea metering control: as shown in fig. 3, the in-coupling urea metering valve 12 is driven by the controller to calculate a PWM period Ta, usually Ta =1s, for driving the in-coupling urea metering valve 12 and an estimated PWM duty ratio Dutya, usually Dutya ranging from 5 to 90%, according to an in-coupling urea demand ma, usually ma ranging from 0 to 2000mg, and an in-coupling urea pipeline 11 pressure collected by an in-coupling urea metering valve pressure sensor 13. The urea injection rate mfa corresponding to the pressure of the in-coupling urea pipeline 11 is calculated by utilizing a 1ms task, the normal mfa range is 0-2000 mg/s, when the in-coupling urea metering valve 12 is driven to be in an opening state, the urea injection rate mfa is subjected to integral calculation to obtain a single actual urea injection amount mb, the normal mb range is 0-2000 mg, and when the single actual urea injection amount mb exceeds the in-coupling urea demand ma, the urea injection is immediately closed. Wherein the deviation mc of the single supply is equal to the single actual urea injection quantity mb minus the coupling ureaThe required quantity ma is that mc = mb-ma, usually the range of mc is 0-50 mg, in the next urea injection process, the original value md of the urea required quantity output by the SCR strategy control module is subtracted by the current urea injection quantity deviation mc to obtain the next in-coupling urea required quantity ma, usually the range of md is 0-2000 mg next Usually ma next The range is 0-2000 mg, the deviation of the urea injection amount at this time is compensated in the next injection process, the actual urea supply amount is finally ensured to be consistent with the urea demand amount, the control deviation range is within +/-3%, and the requirement of the coupling SCR control on the urea supply precision is met.
And (3) urea filter element blockage diagnosis: the urea filter element blockage diagnosis is carried out by using the pressure deviation of the urea tank pressure sensor 10 and the inlet coupling urea metering valve pressure sensor 13, that is, when the condition that the urea pressure acquired by the inlet coupling urea metering valve pressure sensor 13 exceeds a threshold Pd is satisfied, usually Pd =600kPa, if the pressure of the inlet coupling urea pipeline 11 acquired by the inlet coupling urea metering valve pressure sensor 13 is less than a pressure threshold Pe, usually Pe =300kPa, and the maintenance time exceeds a threshold Ton, usually Ton =10s, it is determined that the urea filter element has a blockage fault. In particular, the blockage of the urea filter element does not mean the blockage of the second urea filter element 6, but also comprises the blockage failure caused by the bending of the inlet coupling urea pipeline 11.
Aiming at a urea supply module, the urea supply module mainly comprises a urea filter element I5, a urea pipeline 2, a urea metering valve 14 and a urea metering valve pressure sensor 15, and the functions of the urea supply module mainly comprise a urea metering supply control function and urea filter element blockage diagnosis, and the urea supply module specifically comprises the following steps:
urea dosing control: as shown in FIG. 3, similar to the in-line urea dosing control, the urea metering valve 14 is driven by the controller to output a urea demand ma according to the SCR control strategy 1 Usually ma 1 The range is 0-3000 mg, and the PWM period Ta for driving the urea metering valve is calculated according to the pressure of the urea pipeline 2 acquired by the urea metering valve pressure sensor 15 1 Usually Ta 1 =1s, and estimated PWM duty Dutya 1 Usually Dutya 1 The range is 0 to 95%. Urea injection corresponding to pressure of urea pipeline 2 calculated by utilizing 1ms taskVelocity mfa 1 In general mfa 1 In the range of 0 to 3000mg/s, and when the urea metering valve 14 is actuated in the open state, the injection rate mfa for urea 1 Integral calculation is carried out to obtain the single actual urea spraying amount mb 1 Generally mb 1 The range is 0-3000 mg, when the single actual urea spraying amount mb 1 Exceeds the urea demand ma 1 At this time, the urea metering valve 14 is immediately closed. Wherein the deviation mc of a single feed 1 Equal to the single actual urea injection amount mb 1 Minus urea demand ma 1 I.e. mc 1 ＝mb 1 –ma 1 Usually mc 1 Is in the range of 0-50 mg, and during the next urea injection process, the original value md of the urea demand output by the SCR strategy control module is used 1 Usually md 1 The range is 0-3000 mg, minus the urea injection quantity deviation mc 1 Obtaining the next urea demand ma next1 Usually ma next1 The range is 0-2000 mg, the deviation of the urea injection amount at this time is compensated in the next injection process, the actual urea supply amount is finally ensured to be consistent with the urea demand amount, the control deviation range is within +/-3%, and the requirement of the coupling SCR control on the urea supply precision is met.
And (3) urea filter element blockage diagnosis: similar to the in-coupling urea metering supply control, the pressure deviation of the urea tank pressure sensor 10 and the urea metering valve pressure sensor 15 is utilized to carry out urea filter element blockage diagnosis, namely when the gas pressure of the urea tank 1 collected by the urea tank pressure sensor 10 exceeds a threshold value Pd 1 Condition satisfied, usually Pd 1 =600kPa, if the pressure of the urea pipeline 2 collected by the urea metering valve pressure sensor 15 is less than the pressure threshold Pe 1 Usually Pe 1 =300kPa, and the holding time exceeds the threshold Ton 1 Generally Ton 1 And 5, judging that the urea filter element has a blockage fault, wherein the blockage of the urea filter element is not only the blockage of the urea filter element one 5, but also the blockage fault caused by bending of the urea pipeline 2.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (9)
1. The supply device for the SCR double-injection urea for the vehicle is characterized by comprising a urea tank, wherein an air inlet valve, an air outlet valve and a urea tank pressure sensor are arranged on the urea tank;
the urea tank is internally provided with a first filter element and a second filter element, the first filter element is sequentially and externally connected with a urea metering component through a urea pipeline, the urea metering component is connected with the front end of the coupling SCR, the second filter element is sequentially and externally connected with a coupling urea metering component through a coupling urea pipeline, and the coupling urea metering component is connected with the front end of the coupling SCR;
a cooling liquid heating pipeline and a urea liquid level sensor are inserted into the urea tank, a heating element is externally connected with the cooling liquid heating pipeline, and the supply device is operated by a controller;
the urea metering assembly comprises a urea metering valve and a urea metering valve pressure sensor, and the in-coupling urea metering assembly comprises an in-coupling urea metering valve and an in-coupling urea metering valve pressure sensor.
2. The supply of claim 1 wherein said intake valve is an intake solenoid valve and said exhaust valve is an exhaust solenoid valve.
3. The supply apparatus according to claim 1, wherein the first and second filter elements are urea cartridges, which are urea cartridges one and two, respectively.
4. The supply apparatus according to claim 1, wherein the heating member is a urea tank heating solenoid valve.
5. The supply of claim 1, wherein the source of gas is an air reservoir.
6. A control method of a supply device according to any one of claims 1-5, characterized in that the control method comprises:
(1) Detecting the ambient temperature and the temperature of the urea tank, and if the ambient temperature and the temperature of the urea tank are lower than temperature thresholds, heating the supply device, wherein the heating of the urea in the urea tank by the heating element is controlled, and meanwhile, the urea inlet pipeline and the urea inlet pipeline are heated;
(2) Ending the heating process in the step (1), if the pressure of the urea tank is lower than the preset pressure, opening an air inlet valve, allowing compressed air in an air source to enter the urea tank, and closing the air inlet valve to start working until the pressure of the urea tank reaches a target pressure;
(3) The controller respectively calculates and outputs the required urea amount of the in-coupling SCR reaction and the SCR reaction through an SCR control module, and respectively sprays the required urea into the exhaust pipe for the vehicle according to the test data of the urea metering valve, the urea metering valve pressure sensor, the in-coupling urea metering valve and the in-coupling urea metering valve pressure sensor;
(4) When the vehicle engine is shut down, the exhaust valve is opened to reduce the pressure in the urea tank to the normal atmospheric pressure of 101.325kPa, and when the pressure in the urea tank reaches the pressure threshold value, the exhaust valve is closed.
7. The control method according to claim 6, characterized in that the temperature threshold value is-7 to-5 ℃, the preset pressure is 650 to 670kPa, the target pressure is 700 to 800kPa, and the pressure threshold value is 20 to 30kPa.
8. The control method of claim 6, wherein the urea metering valve can be judged whether blockage exists or not and flow deviation faults exist through the urea demand and the test value of the urea metering valve pressure sensor.
9. The control method according to claim 6, characterized in that whether the inlet coupling urea metering valve is blocked or has a flow deviation fault can be judged through the urea demand and a test value of a pressure sensor of the inlet coupling urea metering valve.
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