CN111720227B - Emission optimization method and device of natural gas engine and ECU (electronic control Unit) - Google Patents

Emission optimization method and device of natural gas engine and ECU (electronic control Unit) Download PDF

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CN111720227B
CN111720227B CN202010617804.1A CN202010617804A CN111720227B CN 111720227 B CN111720227 B CN 111720227B CN 202010617804 A CN202010617804 A CN 202010617804A CN 111720227 B CN111720227 B CN 111720227B
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engine
oxygen concentration
emission
exhaust
conversion efficiency
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CN111720227A (en
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岳崇会
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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
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • 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
    • F01N9/005—Electrical control of exhaust gas treating apparatus using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1445—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being related to the exhaust flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1452—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being a COx content or concentration
    • F02D41/1453—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being a COx content or concentration the characteristics being a CO content or concentration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1459—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being a hydrocarbon content or concentration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/146—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration
    • F02D41/1461—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration of the exhaust gases emitted by the engine
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/10—Carbon or carbon oxides
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/12—Hydrocarbons
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
    • F02D2200/101—Engine speed
    • 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

Abstract

The invention provides an emission optimization method, device and ECU (electronic control Unit) of a natural gas engine, which comprises the steps of obtaining the running parameters of the engine, the first oxygen concentration at the inlet of a three-way catalyst and the second oxygen concentration at the outlet of the three-way catalyst; determining an original emission amount and an exhaust flow rate of the engine exhaust based on the operation parameters; determining the conversion efficiency of the three-way catalyst according to the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flow; and optimizing the original discharge amount by using the conversion efficiency of the three-way catalyst to obtain the optimized final discharge amount. In this case, NO need to be installed X A sensor that determines a conversion efficiency of the three-way catalyst by determining a first oxygen concentration and a second oxygen concentration of the three-way catalyst, and determining an exhaust flow rate for estimation based on an operating parameter of the engine; and optimizing the original discharge amount determined based on the operation parameters of the engine by using the conversion efficiency to obtain the final discharge amount. The emission of the natural gas engine is optimized, so that the emission obtained after TWC treatment and purification can reach the emission standard.

Description

Emission optimization method and device of natural gas engine and ECU (electronic control Unit)
Technical Field
The invention relates to the technical field of data processing, in particular to an emission optimization method and device of a natural gas engine and an ECU (electronic control unit).
Background
The three-way catalyst of the engine is a natural gas engine aftertreatment core component, and when the natural engine runs, the internal combustion engine of the engine burns fuel such as: burning methane CH 4 Carbon monoxide CO, nitrogen oxides NOx, hydrogen carbon compounds HC, and the like in the engine exhaust gas causing air pollution are generated, and at present, the engine exhaust gas causing air pollution is converted into harmless gas by using a Three-way catalytic converter (TWC).
Because it cannot be determined whether the emission quantity of the tail gas discharged by the engine after being treated and purified by a three-way catalyst (TWC) can reach the emission standard, how to provide the emission optimization scheme of the natural gas engine in the embodiment of the invention is that NO is not required to be installed X In the case of the sensor, the emission of the natural gas engine can be optimized by estimating and determining the emission of the engine, so that the emission obtained after TWC treatment and purification can reach the emission standard, which is a problem to be solved urgently.
Disclosure of Invention
In view of this, embodiments of the present invention provide an emission optimization method and apparatus for a natural gas engine, and an ECU, so as to optimize the emission of the natural gas engine, so that the emission obtained after TWC processing and purification can reach the emission standard.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
the first aspect of the embodiment of the invention shows an emission optimization method of a natural gas engine, which comprises the following steps:
obtaining operating parameters of the engine, a first oxygen concentration at an inlet of a three-way catalyst and a second oxygen concentration at an outlet, the operating parameters including at least an exhaust temperature;
determining an original emission amount and an exhaust flow rate of the engine exhaust based on the operating parameters;
determining a conversion efficiency of a three-way catalyst according to the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flow;
and optimizing the original emission by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final emission.
Optionally, the determining the original emission amount and the exhaust flow of the engine exhaust based on the operating parameters at least includes:
searching a first relation table based on the rotating speed and the accelerator opening degree to obtain initial discharge capacity;
searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient;
correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbons and the original emission of nitrogen oxides;
and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
Optionally, the operation parameters at least include engine speed, accelerator opening, excess air coefficient, intake air amount and gas amount, and the determining of the original emission amount and the exhaust flow amount of the engine exhaust based on the operation parameters includes:
searching a third relation table based on the rotating speed and the air inflow to obtain an initial discharge amount;
searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient;
correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbon and the original emission of oxynitride;
and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
Optionally, the determining the conversion efficiency of the three-way catalyst according to the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flow rate includes:
calculating the ratio of the first oxygen concentration and the second oxygen concentration to obtain the air-fuel ratio of the engine;
searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient;
and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency.
Optionally, after determining the conversion efficiency of the three-way catalyst according to the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flow, the method further includes:
and determining the oxygen storage amount of the three-way catalyst according to the difference value of the first oxygen concentration and the second oxygen concentration, and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
The second aspect of the embodiment of the invention discloses an emission optimization device of a natural gas engine, which comprises:
an acquisition module to acquire an operating parameter of an engine, a first oxygen concentration at an inlet of a three-way catalyst, and a second oxygen concentration at an outlet, the operating parameter including at least an exhaust temperature;
an engine original emission estimation model for determining an original emission amount and an exhaust flow rate of engine exhaust based on the operation parameters;
a conversion estimation model for determining a conversion efficiency of the three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate;
and the optimization module is used for optimizing the original emission by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final emission.
Optionally, the operation parameters at least include an engine speed, an accelerator opening, an excess air coefficient, an intake air amount, and a gas amount, and the engine original emission estimation model is specifically configured to: searching a first relation table based on the rotating speed and the accelerator opening degree to obtain initial discharge capacity; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbons and the original emission of nitrogen oxides; and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
Optionally, the conversion estimation model is specifically used for: calculating the ratio of the first oxygen concentration to the second oxygen concentration to obtain the air-fuel ratio of the engine; searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient; and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the initial conversion efficiency.
Optionally, the method further includes:
and the oxygen storage amount estimation module is used for determining the oxygen storage amount of the three-way catalyst according to the difference value of the first oxygen concentration and the second oxygen concentration after the conversion efficiency of the three-way catalyst is determined by the conversion rate estimation model, and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
A third aspect of an embodiment of the present invention discloses an electronic control unit ECU including: a processor and a memory, the memory having stored therein a computer program, the processor executing the computer program to implement the method for emissions optimization of a natural gas engine as disclosed in the first aspect of the embodiments of the present invention.
Based on the emission optimization method, the device and the ECU of the natural gas engine provided by the embodiment of the invention, the method comprises the following steps: obtaining an operating parameter of the engine, a first oxygen concentration at an inlet of the three-way catalyst, and a second oxygen concentration at an outlet, the operating parameter including at least an exhaust temperature; determining an original emission amount and an exhaust flow rate of the engine exhaust based on the operation parameters; determining the conversion efficiency of the three-way catalyst according to the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flow; and optimizing the original discharge capacity by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final discharge capacity. In the embodiment of the present invention, NO installation is not required X A sensor that determines a conversion efficiency of the three-way catalyst by determining an exhaust flow rate for estimation from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine; and determining the original emission of the engine based on the operation parameters of the engine by optimizing the conversion efficiency to obtain the optimized final emission. The emission of the natural gas engine is optimized, so that the emission obtained after TWC treatment and purification can reach the emission standard.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic flow diagram illustrating a method for emissions optimization for a natural gas engine according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a process for determining the raw emissions and exhaust flow of engine exhaust in accordance with an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating another process for determining the original exhaust emission and exhaust flow of an engine according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart illustrating a process for determining conversion efficiency of a three-way catalyst according to an embodiment of the present invention;
FIG. 5 is a schematic flow diagram of another method for emissions optimization for a natural gas engine according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of an emission optimization device of a natural gas engine according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of an emission optimization device for a natural gas engine according to an embodiment of the present invention;
fig. 8 is an architecture diagram of an application of an ECU to optimize emissions from a natural gas engine according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the embodiment of the present invention, NO need to be installed X A sensor that estimates by determining an exhaust flow rate from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine,determining the conversion efficiency of the three-way catalyst; and determining the original emission of the engine based on the operation parameters of the engine by optimizing the conversion efficiency to obtain the optimized final emission. The emission of the natural gas engine is optimized, so that the emission obtained after TWC treatment and purification can reach the emission standard.
The embodiment of the invention provides an emission optimization method and device of a natural gas engine, which are mainly applied to the interior of the engine. In the process of engine operation, obtaining the operating parameters of the engine, and implementing emission optimization of the natural gas engine through an engine original emission estimation model and a conversion rate estimation model, wherein a specific flow for estimating the emission of the natural gas engine based on the engine original emission estimation model and the TWC conversion rate estimation model is as follows:
in the embodiment of the invention, the process of obtaining the operating parameters of the engine and realizing the emission optimization of the natural gas engine through the engine original emission estimation model and the conversion rate estimation model is controlled by an Electronic Control Unit (ECU) in the engine.
Referring to fig. 1, a schematic flow chart of an emission optimization method of a natural gas engine provided in an embodiment of the present invention includes:
step S101: an operating parameter of the engine, a first oxygen concentration at an inlet of the three-way catalyst, and a second oxygen concentration at an outlet are obtained.
In step S101, the operating parameter includes at least an exhaust gas temperature.
In the specific implementation process of step S101, the operating parameters of the engine are obtained in real time, and a first oxygen concentration collected by an oxygen sensor at an inlet of the TWC, that is, a current upstream oxygen concentration of the TWC, is obtained in real time; and acquiring the second oxygen concentration collected by the oxygen sensor at the outlet of the TWC in real time, namely the current downstream oxygen concentration of the TWC.
Step S102: the original emissions and exhaust flow of engine exhaust are determined based on the operating parameters.
In the process of implementing step S102, the operation parameters are used as input of an engine original emission estimation model to be processed, and the original emission amount and the exhaust flow rate of the engine exhaust gas are output. The engine original emission estimation model is established based on the corresponding relation of historical operation parameters, historical emission and historical exhaust flow.
In one embodiment of the present invention, a process of establishing an engine original emission estimation model based on a correspondence relationship between a historical operating parameter, a historical emission amount, and a historical exhaust flow rate includes the steps of:
step S11: and acquiring historical operating parameters, historical emission and historical exhaust flow of the engine.
In step S11, the historical operating parameters include engine speed, accelerator opening, excess air ratio, and gas amount.
In the specific implementation of step S11, the engine speed, the accelerator opening, the excess air factor, the gas amount, the historical emission amount, and the historical exhaust flow rate of the engine are acquired over a preset historical time.
It should be noted that the preset historical time is set through a plurality of experiments, and may also be set through experience by a person skilled in the art.
The excess air ratio refers to the mass ratio of the amount of air actually supplied per 1 kg of fuel burned to the theoretically required amount of air.
Step S12: and establishing a first relation table according to the rotating speed of the engine, the opening degree of the accelerator and the initial discharge amount.
In the process of embodying step S12, a first relationship table is created based on the correspondence between the engine speed and the accelerator opening as inputs and the initial discharge amount as an output.
The initial emissions refer to the historical CO emissions, HC emissions, and nox emissions X And (4) discharging the amount.
Step S13: and establishing a second relation table according to the excess air coefficient, the gas quantity and the correction coefficient.
In the process of embodying step S13, a second relationship table is created based on the correspondence between the excess air factor and the gas amount as inputs, and the correction factor as an output.
Step S14: and establishing an original emission estimation model of the engine based on the established first relation table, the second relation table, the historical exhaust flow and the historical emission.
In another embodiment of the present invention, a process of establishing an engine original emission estimation model based on a corresponding relationship between a historical operating parameter, a historical emission amount, and a historical exhaust flow rate, includes the steps of:
step S21: and acquiring historical operating parameters, historical emission and historical exhaust flow of the engine.
It should be noted that the specific implementation process of step S22 is the same as the specific implementation process of step S11 shown in the above embodiment of the present invention, and reference may be made to this.
Step S22: and establishing a third relation table according to the engine speed, the air intake quantity and the initial discharge quantity.
In the process of embodying step S22, a first relationship table is established based on the correspondence relationship between the engine speed and the intake air amount as inputs, and the initial discharge amount as an output.
The initial emissions refer to the historical CO emissions, HC emissions, and nox emissions X And (4) discharging the amount.
Step S23: and establishing a second relation table according to the excess air coefficient, the gas quantity and the correction coefficient.
Step S24: and establishing an original emission estimation model of the engine based on the established first relation table, the second relation table, the historical exhaust flow and the historical emission.
It should be noted that the specific implementation processes of step S23 and step S24 are the same as the specific implementation processes of step S13 and step S14 shown in the above-mentioned embodiment of the present invention, and can be referred to each other.
Step S103: the conversion efficiency of the three-way catalyst is determined based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate.
In the process of implementing step S103 specifically, the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate are processed as inputs of a conversion rate estimation model, which is established based on the correspondence relationship between the oxygen concentration parameter upstream and downstream of the historical TWC, the historical exhaust emission, and the historical exhaust flow rate, and the conversion efficiency of the three-way catalyst is output.
It should be noted that, the process of establishing the conversion rate estimation model based on the corresponding relationship between the oxygen concentration parameter of the upstream and downstream of the historical TWC, the historical emission amount and the historical exhaust flow rate includes the following steps:
step S31: and acquiring oxygen concentration parameters upstream and downstream of the historical TWC, historical emission and historical exhaust flow.
In the process of implementing step S31 specifically, the first oxygen concentration collected by the oxygen sensor upstream of the TWC history and the second oxygen concentration collected by the oxygen sensor downstream of the TWC history, as well as the history exhaust emission amount and the history exhaust flow rate, are acquired.
Step S32: and establishing a fourth relation table according to the relation among the historical emission amount, the historical exhaust flow and the exhaust coefficient.
In the process of implementing step S32 specifically, a fourth relationship table is established for the relationship between the historical discharge amount and the historical discharge flow rate as inputs and the discharge coefficient as an output.
Step S33: and establishing a conversion rate estimation model according to the established fourth relation table and the oxygen concentration parameters upstream and downstream of the historical TWC.
Step S104: and optimizing the original discharge amount by using the conversion efficiency of the three-way catalyst to obtain the optimized final discharge amount.
In the process of specifically implementing step S104, the product of the conversion efficiency of the three-way catalyst and the original emission amount is calculated to obtain an estimated final emission amount, so as to optimize the emission of the natural gas engine.
In an embodiment of the invention, operating parameters of the engine, a first oxygen concentration at an inlet of the three-way catalyst, and a second oxygen concentration at an outlet are obtained, the operating parameters including at least an exhaust temperature; determining an original emission amount and an exhaust flow rate of the engine exhaust based on the operating parameters; based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature and the exhaust flowConversion efficiency of the three-way catalyst; and optimizing the original discharge capacity by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final discharge capacity. In the scheme, NO need for installing NO X A sensor that determines a conversion efficiency of the three-way catalyst by determining an exhaust flow rate for estimation from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine; and determining the original emission of the engine based on the operation parameters of the engine by optimizing the conversion efficiency to obtain the optimized final emission. So as to optimize the emission of the natural gas engine, and the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the method for optimizing the emission of the natural gas engine shown in the above embodiment of the present invention, in an embodiment mode of the embodiment of the present invention, if the operation parameters at least include the engine speed, the accelerator opening, the excess air coefficient, the intake air amount, and the gas amount, the process of determining the original emission amount and the exhaust gas flow amount of the engine exhaust gas based on the operation parameters in step S102 is executed, as shown in fig. 2, and includes the following steps:
step S201: and searching a first relation table based on the rotating speed and the accelerator opening degree to obtain the initial discharge amount.
In step S201, the first relational table is a two-dimensional array table. The first relation table is used for storing the relation among the rotating speed, the accelerator opening degree and the initial discharge amount.
In the embodiment of the invention, the correspondence between the rotation speed and the accelerator opening as inputs and the initial discharge amount as an output is stored in the form of the first relationship table. In the process of implementing step S201 specifically, a first relation table is searched according to the current engine speed and accelerator opening, that is, the opening of the accelerator pedal of the entire vehicle, so as to obtain the initial discharge amount corresponding to the current engine speed and accelerator opening.
Note that the initial discharge amount includes: initial emission of CO, HC, and NO X The initial discharge amount.
Step S202: and searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient.
In step S202, the second relational table is a two-dimensional array table for storing the relationship between the excess air ratio, the gas amount, and the correction ratio.
In the embodiment of the invention, the correspondence between the excess air coefficient and the gas amount as inputs and the correction coefficient as outputs is stored in the form of the second relationship table. In the process of specifically implementing step S202, a second relation table is searched according to the currently obtained excess air coefficient and gas quantity, and a correction coefficient corresponding to the current excess air coefficient and gas quantity is obtained.
Step S203: and correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine.
In step S203, the original emissions of the engine exhaust gas include the original emissions of CO, HC, and NO X The original discharge amount.
In the process of specifically implementing step S203, the initial emission value of the engine exhaust is corrected according to the product of the correction coefficient and the initial emission value, so as to obtain the original emission value of the engine exhaust.
Step S204: and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
In the process of specifically implementing step S204, the intake air amount and the gas amount are converted into numerical values of the same unit, and the converted intake air amount and gas amount are added to obtain the exhaust flow rate of the current engine.
In the embodiment of the present invention, NO installation is not required X The sensor searches a first relation table according to the current rotating speed and the current accelerator opening degree of the engine and determines the initial discharge amount; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; and then correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine. And calculating according to the air inflow and the gas quantity to obtain the exhaust flow. So as to determine the conversion efficiency of the three-way catalyst by estimating from a first oxygen concentration at the inlet of the three-way catalyst, a second oxygen concentration at the outlet, and the flow rate of the exhaust gas; reuse of optimized conversion efficiency to optimize raw emissionsAnd obtaining the optimized final emission to optimize the emission of the natural gas engine, so that the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the method for optimizing the emission of the natural gas engine shown in the above embodiment of the present invention, in another embodiment mode of the embodiment of the present invention, if the operation parameters at least include the engine speed, the accelerator opening, the excess air ratio, the intake air amount, and the gas amount, the process of determining the original emission amount and the exhaust gas flow amount of the engine exhaust gas based on the operation parameters in step S102 is executed, as shown in fig. 3, and includes the following steps:
step S301: and searching a third relation table based on the rotating speed and the air inflow amount to obtain the initial discharge amount.
In step S301, the third relation table is a two-dimensional array table. The third relation table is for storing a relation between the rotation speed, the intake air amount, and the initial discharge amount.
In the embodiment of the invention, the correspondence relationship between the rotation speed and the intake air amount as inputs and the initial discharge amount as an output is stored in the form of the third relation table. In the process of specifically implementing step S301, the third relation table is searched according to the current engine speed and the current intake air amount, and the initial discharge amount corresponding to the current engine speed and the current intake air amount is obtained.
Note that the initial discharge amount includes: initial CO emissions, initial HC emissions, and initial NO X And (4) discharging the amount.
Step S302: and searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient.
Step S303: and correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine.
Step S304: and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
It should be noted that the specific implementation process of step S302 to step S304 is the same as the specific implementation process of step S202 to step S204 shown in the above embodiments, and reference may be made to each other.
In the embodiment of the present invention, NO installation is not required X The sensor searches a first relation table through the current rotating speed and air inflow of the engine and determines the initial discharge amount; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; and then correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine. And calculating according to the air inflow and the gas quantity to obtain the exhaust flow. So as to determine the conversion efficiency of the three-way catalyst by estimating from a first oxygen concentration at the inlet of the three-way catalyst, a second oxygen concentration at the outlet, and the flow rate of the exhaust gas; and optimizing the original emission by using the optimized conversion efficiency to obtain the optimized final emission so as to optimize the emission of the natural gas engine, so that the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the emission optimization method of the natural gas engine shown in the above-described embodiment of the present invention, the process of determining the conversion efficiency of the three-way catalyst from the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate at step S103 is performed, as shown in fig. 4, including the steps of:
step S401: and calculating the ratio of the first oxygen concentration and the second oxygen concentration to obtain the air-fuel ratio of the engine.
Since the conversion efficiency of the TWC is affected by the catalytic efficiency, i.e., the conversion efficiency of the TWC drops sharply when the catalytic light-off temperature is too low; catalytic efficiency of the TWC is also lost when the catalytic light-off temperature is too high. The conversion efficiency of the three-way catalyst is related to the air-fuel ratio of the engine, and the catalytic efficiency of the air-fuel ratio is the best in practice. Therefore, in the process of embodying step S402, the air-fuel ratio of the engine is found from the ratio of the first oxygen concentration and the second oxygen concentration.
The air-fuel ratio is a ratio of mass between air and fuel in the air-fuel mixture. Generally expressed in grams of air consumed per gram of fuel burned.
Step S402: and searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain the exhaust coefficient.
In step S402, the fourth relational table is a two-dimensional array table. The fourth relational table is used for storing the relationship among the exhaust gas temperature, the exhaust gas flow rate, and the exhaust gas coefficient.
In the embodiment of the present invention, the correspondence relationship between the exhaust gas temperature and the exhaust gas flow rate as inputs and the exhaust gas coefficient as an output is stored in the form of the fourth relationship table. In the process of specifically implementing step S402, the fourth relation table is searched according to the current exhaust temperature and exhaust flow rate, and the exhaust coefficient corresponding to the current exhaust temperature and exhaust flow rate is obtained.
Step S403: and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency.
In the process of implementing step S403 specifically, the conversion efficiency of the engine is obtained by performing multiplication calculation according to the air-fuel ratio and the exhaust coefficient of the engine.
In the embodiment of the present invention, NO installation is not required X A sensor that obtains an air-fuel ratio of the engine by calculating a ratio of the first oxygen concentration and the second oxygen concentration; searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient; and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency. And then determining the original emission of the engine based on the operation parameters of the engine by utilizing the optimization of the optimized conversion efficiency to obtain the optimized final emission. So as to optimize the emission of the natural gas engine, and the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the method for optimizing the emission of the natural gas engine shown in the embodiment of the invention, referring to fig. 5, the embodiment of the invention also shows a flow chart of another method for optimizing the emission of the natural gas engine, wherein the method comprises the following steps:
step S501: an operating parameter of the engine, a first oxygen concentration at an inlet of the three-way catalyst, and a second oxygen concentration at an outlet are obtained.
In step S501, the operating parameters include at least an exhaust temperature.
Step S502: the original emissions and exhaust flow of engine exhaust are determined based on the operating parameters.
Step S503: the conversion efficiency of the three-way catalyst is determined based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate.
It should be noted that the specific implementation process of step S501 to step S503 is the same as the specific implementation process of step S101 to step S103 shown in the above embodiment, and can be referred to each other.
Step S504: an oxygen storage amount of the three-way catalyst is determined based on a difference between the first oxygen concentration and the second oxygen concentration.
In actual application, the three-way catalyst is aged and failed, and the oxygen storage amount of the TWC can represent the catalytic capability of the TWC, namely the conversion efficiency and the ageing degree of the TWC. In the process of specifically implementing the step S504, whether the TWC is in the preset condition is judged through the accelerator opening, the rotation speed, the excess air coefficient, the intake air amount, the gas amount, the first oxygen concentration, the second oxygen concentration, the exhaust gas flow rate, and the exhaust gas temperature, and when it is determined that the TWC is in the preset condition, a difference value between the first oxygen concentration and the second oxygen concentration is calculated to obtain the oxygen storage amount of the three-way catalyst.
It should be noted that the preset condition may be set through a plurality of experiments, or may be set through experience by a person skilled in the art, for example: the preset condition refers to the working condition of the engine in the downhill, wherein the engine does not inject fuel, but the engine still rotates and the air inflow is available.
Step S505: and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
In the embodiment of the present invention, in order to prevent the influence of the aging or the failure of the three-way catalyst on the conversion efficiency of the TWC, the conversion efficiency needs to be corrected by the oxygen storage amount, and therefore, in the process of specifically implementing step S505, the product of the oxygen storage amount and the conversion efficiency is calculated to correct the conversion efficiency of the TWC, so as to obtain the corrected conversion efficiency.
Step S506: and optimizing the original discharge capacity by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final discharge capacity.
In the process of implementing step S506 specifically, the product of the corrected conversion efficiency and the original emission amount is calculated to obtain the estimated final emission amount, so as to optimize the emission of the natural gas engine.
In the embodiment of the present invention, NO installation is not required X A sensor that determines a conversion efficiency of the three-way catalyst by determining an exhaust flow rate for estimation from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine; in order to prevent the influence of the aging or failure of the three-way catalyst on the conversion efficiency of the TWC, it is necessary to determine the oxygen storage amount of the three-way catalyst from the difference between the first oxygen concentration and the second oxygen concentration, and correct the conversion efficiency using the oxygen storage amount to correct the conversion efficiency of the TWC to obtain the corrected conversion efficiency. And then, determining the original emission of the engine based on the operation parameters of the engine by optimizing the conversion efficiency to obtain the optimized final emission. So as to optimize the emission of the natural gas engine, and the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the emission optimization method of the natural gas engine shown in the embodiment of the invention, the embodiment of the invention also correspondingly discloses an emission optimization device of the natural gas engine, the emission optimization device of the natural gas engine is controlled by the ECU, and as shown in fig. 6, the emission optimization device of the natural gas engine provided in the embodiment of the invention is schematically shown in the structure.
An obtaining module 601 obtains operating parameters of the engine, the first oxygen concentration at an inlet of the three-way catalyst, and the second oxygen concentration at an outlet, the operating parameters including at least an exhaust temperature.
An engine raw emission estimation model 602 for determining raw emissions and exhaust flow of engine exhaust based on operating parameters.
A conversion estimation model 603 for determining the conversion efficiency of the three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate.
And the optimization module 604 is used for optimizing the original emission by using the conversion efficiency of the three-way catalyst to obtain the optimized final emission.
Optionally, the optimization module 604 may be incorporated into the conversion estimation model 603, i.e. the conversion estimation model 603 comprises the optimization module 604.
It should be noted that, the specific principle and implementation process of each unit in the natural gas engine emission optimization device disclosed in the above embodiment of the present invention are the same as the natural gas engine emission optimization method implemented in the above embodiment of the present invention, and reference may be made to corresponding parts in the natural gas engine emission optimization method disclosed in the above embodiment of the present invention, and details are not repeated here.
In the embodiment of the present invention, NO installation is not required X A sensor that determines a conversion efficiency of the three-way catalyst by determining an exhaust flow rate for estimation from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine; and determining the original emission of the engine based on the operation parameters of the engine by optimizing the conversion efficiency to obtain the optimized final emission. So as to optimize the emission of the natural gas engine, and the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the emission optimization device of the natural gas engine shown in the above embodiment of the present invention, in an implementation manner of the embodiment of the present invention, if the operation parameters at least include the engine speed, the accelerator opening, the excess air ratio, the intake air amount, and the gas amount, the engine original emission estimation model 602 is specifically configured to: searching a first relation table based on the rotating speed and the opening degree of the accelerator to obtain initial discharge; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; correcting the initial discharge amount by using the correction coefficient to obtain the original discharge amount of the tail gas of the engine; and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
It should be noted that the original emissions of the engine exhaust include the original emissions of carbon monoxide, the original emissions of hydrocarbons, and the original emissions of nitrogen oxides.
In the embodiment of the present invention, NO installation is not required X The sensor searches a first relation table according to the current rotating speed and the current accelerator opening degree of the engine and determines the initial discharge amount; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; then, the initial emission is corrected by using the correction coefficient to obtain the original emission of the tail gas of the engineAmount of the compound (A). And calculating according to the air inflow and the gas quantity to obtain the exhaust flow. So as to determine the conversion efficiency of the three-way catalyst by estimating a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet of the three-way catalyst, and the flow rate of the exhaust gas; and optimizing the original emission by using the optimized conversion efficiency to obtain the optimized final emission so as to optimize the emission of the natural gas engine, so that the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the above-described emission optimization device for a natural gas engine according to an embodiment of the present invention, in another implementation manner according to an embodiment of the present invention, if the operation parameters at least include engine speed, accelerator opening, excess air coefficient, intake air amount, and gas amount, the original engine emission estimation model 602 is specifically configured to: searching a third relation table based on the rotating speed and the air inflow to obtain the initial discharge amount; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; correcting the initial discharge amount by using the correction coefficient to obtain the original discharge amount of the tail gas of the engine; and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
It should be noted that the original emissions of the engine exhaust include original emissions of carbon monoxide, original emissions of hydrocarbons, and original emissions of nitrogen oxides.
In the embodiment of the present invention, NO installation is not required X The sensor searches a first relation table through the current rotating speed and air inflow of the engine and determines the initial discharge amount; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; and then correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine. And calculating according to the air inflow and the gas quantity to obtain the exhaust flow. So as to determine the conversion efficiency of the three-way catalyst by estimating a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet of the three-way catalyst, and the flow rate of the exhaust gas; and optimizing the original discharge amount by using the optimized conversion efficiency to obtain the optimized final discharge amount so as to optimize the discharge of the natural gas engine, so that the discharge amount obtained after TWC treatment and purification can reach the discharge standard.
The emission optimization device for the natural gas engine shown based on the above-mentioned embodiment of the present invention, as shown in fig. 7 in combination with fig. 6, further includes:
and the oxygen storage amount estimation module 605 is used for determining the oxygen storage amount of the three-way catalyst according to the difference value of the first oxygen concentration and the second oxygen concentration after the conversion efficiency of the three-way catalyst is determined by the conversion rate estimation model, and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
In the embodiment of the present invention, NO installation is not required X A sensor that obtains an air-fuel ratio of the engine by calculating a ratio of the first oxygen concentration and the second oxygen concentration; searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient; and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency. And then determining the original emission of the engine based on the operation parameters of the engine by utilizing the optimization of the optimized conversion efficiency to obtain the optimized final emission. The emission of the natural gas engine is optimized, so that the emission obtained after TWC treatment and purification can reach the emission standard.
The emission estimation process of the natural gas engine will be described in detail below with reference to an example.
Referring to fig. 8, an architecture diagram of an application for optimizing emissions of a natural gas engine for an ECU.
And inputting the accelerator opening, the rotating speed, the excess air coefficient, the air inflow and the gas quantity of the engine acquired by the acquisition unit into an original engine emission estimation model. The engine original emission estimation model searches a first relation table according to the current engine rotating speed and the accelerator opening to obtain the initial emission corresponding to the current engine rotating speed and the accelerator opening; and searching a second relation table according to the currently obtained excess air coefficient and the gas quantity to obtain a correction coefficient corresponding to the current excess air coefficient and the gas quantity. According to the product of the correction coefficient and the initial emission, correcting the initial emission value of the tail gas of the engine to obtain the original emission of CO, HC and NO X Discharge capacity; and converting the air input and the gas input into a numerical value of the same unit, and adding the converted air input and the converted gas input into a numerical value of the same unit,and obtaining the current exhaust flow of the engine.
And inputting the accelerator opening, the rotating speed, the excess air coefficient, the air inflow, the gas quantity, the first oxygen concentration, the second oxygen concentration, the exhaust flow and the exhaust temperature of the engine, which are acquired by the acquisition unit, into an oxygen storage amount estimation module. The oxygen storage amount estimation module determines the working condition that the TWC is located in the engine downhill through the accelerator opening, the rotating speed, the excess air coefficient, the air inflow, the gas quantity, the first oxygen concentration, the second oxygen concentration, the exhaust flow and the exhaust temperature, and calculates the difference value of the first oxygen concentration and the second oxygen concentration to obtain the oxygen storage amount of the three-way catalyst.
Obtaining original emission of CO, HC and NO by an engine original emission estimation model X The emission amount, the exhaust flow rate and the exhaust temperature, and the oxygen storage amount of the three-way catalyst obtained by the oxygen storage amount estimation module are input into a conversion rate estimation model. The conversion estimation model obtains an air-fuel ratio of the engine based on a ratio of the first oxygen concentration and the second oxygen concentration. And searching a fourth relation table according to the current exhaust temperature and the exhaust flow to obtain an exhaust coefficient corresponding to the current exhaust temperature and the exhaust flow. And then, multiplication is carried out according to the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency of the engine. And then calculating the product of the oxygen storage amount and the conversion efficiency to correct the conversion efficiency of the TWC to obtain the corrected conversion efficiency. And finally, calculating the product of the corrected conversion efficiency and the original emission to obtain the estimated final emission so as to optimize the emission of the natural gas engine.
In the embodiment of the present invention, NO need to be installed X A sensor that determines a conversion efficiency of the three-way catalyst by determining an exhaust flow rate for estimation from a first oxygen concentration at an inlet of the three-way catalyst, a second oxygen concentration at an outlet, and an operating parameter based on the engine; in order to prevent the influence of the aging or the failure of the three-way catalyst on the conversion efficiency of the TWC, it is necessary to determine the oxygen storage amount of the three-way catalyst from the difference between the first oxygen concentration and the second oxygen concentration, and to correct the conversion efficiency using the oxygen storage amount to correct the conversion efficiency of the TWC, resulting in the corrected conversion efficiency. Engine-based operating parameter determination using optimized conversion efficiency optimizationAnd the original emission of the engine to obtain the optimized final emission. The emission of the natural gas engine is optimized, so that the emission obtained after TWC treatment and purification can reach the emission standard.
Based on the emission optimization device of the natural gas engine disclosed by the embodiment of the invention, the modules can be realized by an ECU hardware device consisting of a processor and a memory, and the device specifically comprises the following components: the modules are stored in the memory as program units, and the processor calls the program units in the memory to realize the emission optimization method of the natural gas engine.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement without inventive effort.
Those of skill would further appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the various examples have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A method of emissions optimization for a natural gas engine, the method comprising:
obtaining operating parameters of the engine, a first oxygen concentration at an inlet of a three-way catalyst and a second oxygen concentration at an outlet, the operating parameters including at least an exhaust temperature;
determining an original emission amount and an exhaust flow rate of the engine exhaust based on the operating parameters;
determining a conversion efficiency of a three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate;
optimizing the original discharge capacity by utilizing the conversion efficiency of the three-way catalyst to obtain an optimized final discharge capacity;
determining a conversion efficiency of a three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate includes:
calculating a ratio of a first oxygen concentration and a second oxygen concentration, and obtaining an air-fuel ratio of the engine based on the ratio of the first oxygen concentration and the second oxygen concentration;
searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient;
calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the conversion efficiency;
the first oxygen concentration is collected by an upstream oxygen sensor and the second oxygen concentration is collected by a downstream oxygen sensor.
2. The method of claim 1, wherein the operating parameters include at least engine speed, throttle opening, excess air ratio, intake air amount, and gas amount, and the determining of the raw emission amount and the exhaust flow amount of the engine exhaust based on the operating parameters includes:
searching a first relation table based on the rotating speed and the opening degree of the accelerator to obtain initial discharge;
searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient;
correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbons and the original emission of nitrogen oxides;
and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
3. The method of claim 1, wherein the operating parameters include at least engine speed, throttle opening, excess air ratio, intake air amount, and gas amount, and wherein determining the raw emission amount and exhaust flow amount of the engine exhaust based on the operating parameters comprises:
searching a third relation table based on the rotating speed and the air inflow to obtain an initial discharge amount;
searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient;
correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbons and the original emission of nitrogen oxides;
and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
4. The method of claim 1, after determining a conversion efficiency of a three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate, further comprising:
and determining the oxygen storage amount of the three-way catalyst according to the difference value of the first oxygen concentration and the second oxygen concentration, and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
5. An emission optimization device for a natural gas engine, the device comprising:
an acquisition module to acquire an operating parameter of an engine, a first oxygen concentration at an inlet of a three-way catalyst, and a second oxygen concentration at an outlet, the operating parameter including at least an exhaust temperature;
an engine original emission estimation model for determining an original emission amount and an exhaust flow rate of engine exhaust based on the operation parameters;
a conversion estimation model for determining a conversion efficiency of the three-way catalyst based on the first oxygen concentration, the second oxygen concentration, the exhaust temperature, and the exhaust flow rate;
the optimization module is used for optimizing the original discharge capacity by utilizing the conversion efficiency of the three-way catalyst to obtain the optimized final discharge capacity;
the conversion estimation model is particularly useful for:
calculating a ratio of a first oxygen concentration and a second oxygen concentration, and obtaining an air-fuel ratio of the engine based on the ratio of the first oxygen concentration and the second oxygen concentration; searching a fourth relation table based on the exhaust temperature and the exhaust flow to obtain an exhaust coefficient; and calculating the product of the air-fuel ratio and the exhaust coefficient of the engine to obtain the initial conversion efficiency, wherein the first oxygen concentration is acquired by an upstream oxygen sensor, and the second oxygen concentration is acquired by a downstream oxygen sensor.
6. The apparatus of claim 5, wherein the operating parameters include at least engine speed, throttle opening, excess air ratio, intake air amount, and gas amount, and wherein the engine raw emission estimation model is specifically configured to: searching a first relation table based on the rotating speed and the accelerator opening degree to obtain initial discharge capacity; searching a second relation table based on the excess air coefficient and the gas quantity to obtain a correction coefficient; correcting the initial emission by using the correction coefficient to obtain the original emission of the tail gas of the engine, wherein the original emission of the tail gas of the engine comprises the original emission of carbon monoxide, the original emission of hydrocarbons and the original emission of nitrogen oxides; and calculating according to the air inflow and the gas quantity to obtain the exhaust flow.
7. The apparatus of claim 5, further comprising:
and the oxygen storage amount estimation module is used for determining the oxygen storage amount of the three-way catalyst according to the difference value of the first oxygen concentration and the second oxygen concentration after the conversion efficiency of the three-way catalyst is determined by the conversion rate estimation model, and correcting the conversion efficiency by using the oxygen storage amount to obtain the corrected conversion efficiency.
8. An Electronic Control Unit (ECU), characterized in that the ECU comprises: a processor and a memory, the memory having stored therein a computer program, the processor executing the computer program to implement the emission optimization method of a natural gas engine according to any one of claims 1 to 4.
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