CN111946469B - Control method and control system for EGR working area of exhaust gas recirculation system - Google Patents

Control method and control system for EGR working area of exhaust gas recirculation system Download PDF

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Publication number
CN111946469B
CN111946469B CN202010706201.9A CN202010706201A CN111946469B CN 111946469 B CN111946469 B CN 111946469B CN 202010706201 A CN202010706201 A CN 202010706201A CN 111946469 B CN111946469 B CN 111946469B
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valve
egr
opening degree
vgt
actual
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CN111946469A (en
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庹汉郧
李仕成
陈龙
肖文涛
周明星
张春娇
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Dongfeng Motor Corp
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Dongfeng Motor Corp
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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
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0077—Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • F02B37/12—Control of the pumps
    • F02B37/24—Control of the pumps by using pumps or turbines with adjustable guide vanes
    • 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
    • F02D41/0002—Controlling intake air
    • F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
    • 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
    • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/02—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
    • 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
    • F02D41/0002—Controlling intake air
    • F02D2041/0017—Controlling intake air by simultaneous control of throttle and exhaust gas recirculation
    • 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
    • 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 application discloses a control method and a control system for an EGR (exhaust gas recirculation) working area of an exhaust gas recirculation system, wherein the control method comprises the following steps: according to a preset parameter pulse spectrum under the operation condition, the required air inflow under the operation condition is solved; acquiring the actual rotating speed of the engine, determining the required front-rear pressure ratio of the EGR valve according to the actual rotating speed and the required air inflow, and driving the VGT valve and the throttle valve to respond by adopting open-loop control; acquiring an actual front-rear pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve according to the required front-rear pressure ratio; controlling the opening degree of the throttle valve according to a preset parameter pulse spectrum and the actual opening degree of the VGT valve; and acquiring the actual EGR rate of the EGR according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and a preset parameter pulse spectrum so as to enable the actual front-back pressure ratio of the EGR valve to approach the required front-back pressure ratio. According to the EGR valve control system, the opening degree of the VGT valve and the opening degree of the throttle valve are controlled by taking the front-back pressure ratio of the EGR valve as a control target, so that the opening degree of the EGR valve is controlled, and the EGR working area can be effectively enlarged.

Description

Control method and control system for EGR working area of exhaust gas recirculation system
Technical Field
The application relates to the technical field of vehicle control, in particular to a control method and a control system for an EGR (exhaust gas recirculation) working area of an exhaust gas recirculation system.
Background
With the increasing strictness of the regulations on the emission and oil consumption of automobile exhaust, how to effectively reduce the oil consumption of gasoline engine to achieve the goal of the regulations on oil consumption becomes a difficult point. Among them, the exhaust gas recirculation technology is an important technology for improving the performance and emission of the engine because it introduces high-temperature exhaust gas into the cylinder after cooling, reduces pumping loss, weakens knocking, and improves combustion quality in the cylinder.
Generally, an EGR of an exhaust gas recirculation system is driven by a pressure difference, and it is required to satisfy that the pressure before an EGR valve is larger than the pressure after the EGR valve, otherwise an exhaust gas recirculation device cannot work normally. In the case of a gasoline engine with a turbocharger VGT, the pressure before the turbine is used as the pressure before the EGR valve, and the pressure after the throttle valve is used as the pressure after the EGR valve, and the opening degree of the throttle valve is gradually increased with the increase of the load, so that the pressure difference before and after the EGR valve is gradually reduced, and when the throttle valve is fully opened, the turbocharger VGT is operated, but at this time, the pressure before the EGR valve is lower than the pressure after the EGR valve, and the pressure difference before and after the EGR valve is not enough to drive the EGR, which obviously limits the EGR operation region of the exhaust gas recirculation system.
In the related art, the conventional control method of the turbocharger VGT is to ensure the intake pressure as the control purpose, and although the control method reduces the pumping loss and reduces the fuel consumption, the VGT is opened under the condition that the throttle valve is fully opened, and the influence of the EGR on the fuel consumption is ignored.
Disclosure of Invention
The embodiment of the application provides a control method and a control system for an EGR (exhaust gas recirculation) working area of an exhaust gas recirculation system, on the premise that air inflow is guaranteed through the opening degrees of a VGT valve and a throttle valve, the opening degrees of the VGT valve and the throttle valve are controlled by taking the front-back pressure ratio of the EGR valve as a control target, the opening degree of the EGR valve is further controlled, and the VGT valve, the throttle valve and the EGR valve act in a synergistic manner, so that the EGR working area is effectively enlarged, and oil consumption is further reduced.
In one aspect, an embodiment of the present application provides a method for controlling an EGR operating region of an exhaust gas recirculation system, the method comprising:
presetting parameter pulse spectrums under various working conditions of an engine;
constructing a torque model and an air quantity model according to the parameter pulse spectrum under the operating condition, and solving the required air inflow under the operating condition;
acquiring the actual rotating speed of an engine under the operating condition, determining the required front-to-back pressure ratio of the EGR valve according to the actual rotating speed and the required air inflow, and driving the VGT valve and the throttle valve to respond by adopting open-loop control;
acquiring an actual front-rear pressure ratio of the EGR valve under the operating condition, and controlling the opening degree of the VGT valve according to the required front-rear pressure ratio;
controlling the opening of the throttle valve according to the parameter pulse spectrum under the operating condition and the actual opening of the VGT valve;
and acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and a preset parameter pulse spectrum under an operation condition so as to enable the actual front-back pressure ratio of the EGR valve to approach the required front-back pressure ratio.
In this embodiment, preferably, the step of obtaining the actual front-to-rear pressure ratio of the EGR valve under the operating condition and controlling the opening degree of the VGT valve according to the required front-to-rear pressure ratio includes:
when the EGR working area is in a supercharging area, solving to obtain the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve according to the opening degree of the VGT valve;
when the EGR working area is in a non-supercharging area, solving the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve to be zero.
Preferably, the parameters in the parameter pulse spectrum include:
the control method comprises the steps of required torque, friction loss, pumping loss, ignition efficiency, air-fuel ratio efficiency, combustion efficiency, required front-back pressure ratio of an EFG valve, charging efficiency, VGT valve opening degree open-loop control quantity, throttle valve pressure drop open-loop control quantity, corresponding relation between throttle valve area and opening degree of a throttle valve and required EGR rate.
Preferably, the specific steps of constructing the torque model and the air volume model according to the parameter pulse spectrum under the operating condition and solving the required air volume under the operating condition are as follows:
calculating to obtain a required total torque according to the required torque, friction loss, pumping loss, ignition efficiency and air-fuel ratio efficiency under a preset operation condition;
dividing the required total torque by the combustion efficiency and the fuel calorific value of the actual oil product to obtain the required fuel quantity;
and determining the required air inflow according to the product of the required fuel quantity and the air-fuel ratio of the actual oil product.
Preferably, the specific steps of determining the required front-rear pressure ratio of the EGR valve according to the actual rotation speed and the required intake air amount, and driving the VGT valve and the throttle valve to respond by open-loop control include:
inquiring a preset parameter pulse spectrum under an operation condition according to the actual rotating speed and the required air inflow, and determining a required front-back pressure ratio of an EGR valve, a VGT valve opening open-loop control quantity and a throttle valve pressure drop open-loop control quantity which are preset under the operation condition;
and driving the VGT valve and the throttle valve to respond in a feedforward mode according to the opening open-loop control quantity of the VGT valve and the pressure drop open-loop control quantity of the throttle valve.
Preferably, when the EGR operation region is in the supercharging region, the specific step of obtaining the opening amount of the VGT valve by solving according to the actual front-rear pressure ratio of the EGR valve and the required front-rear pressure ratio, and controlling the opening amount of the VGT valve according to the opening amount of the VGT valve includes:
solving the opening increment of the VGT valve according to the difference value of the required front-back pressure ratio and the actual front-back pressure ratio;
obtaining the opening amount of the VGT valve according to the sum of the opening increment of the VGT valve and the preset opening open-loop control amount of the VGT valve;
and controlling the opening degree of the VGT valve according to the opening degree control of the VGT valve.
Preferably, the specific step of solving the opening increment of the VGT valve according to the difference between the required front-rear pressure ratio and the actual front-rear pressure ratio is as follows:
and solving a proportional term, an integral term and a differential term of the difference value of the required front-back pressure ratio and the actual front-back pressure ratio with respect to time, respectively multiplying the difference value by a preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening increment of the VGT valve.
Preferably, the specific step of controlling the opening degree of the throttle valve according to the parameter pulse spectrum under the operating condition and the actual opening degree of the VGT valve is as follows:
acquiring the front supercharging pressure of a throttle valve according to the actual opening of the VGT valve;
determining the required pressure behind a throttle valve according to the required air inflow under the operating condition of the engine and the preset inflation efficiency;
calculating the required area of the throttle according to the pressure drop of the supercharging pressure in front of the throttle and the required pressure behind the throttle;
and inquiring corresponding throttle opening amount in the corresponding relation between the preset throttle area and the throttle opening according to the required area of the throttle, and controlling the throttle opening according to the inquired throttle opening amount.
Preferably, the specific steps of obtaining an actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and a preset parameter pulse spectrum under an operating condition include:
acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve;
according to the difference value between the actual EGR rate and the preset required EGR rate under the operation condition, solving a proportional term, an integral term and a differential term of the difference value with respect to time, respectively multiplying the difference value by a corresponding preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening amount of the EGR valve;
and controlling the opening degree of the EGR valve according to the opening degree of the EGR valve.
In another aspect, an embodiment of the present application further provides a control system for an EGR operation region of an exhaust gas recirculation system, the control system including:
a memory for storing executable instructions;
and the processor is connected with the memory and is used for operating the executable instructions to execute the control method of the EGR working area of the exhaust gas recirculation system.
The beneficial effect that technical scheme that this application provided brought includes:
the embodiment of the application provides a control method and a control system for an EGR (exhaust gas recirculation) working area of an exhaust gas recirculation system, on the premise that air inflow is guaranteed through the opening degrees of a VGT valve and a throttle valve, the opening degrees of the VGT valve and the throttle valve are controlled by taking the front-back pressure ratio of the EGR valve as a control target, and then the opening degree of the EGR valve is controlled, and the VGT valve, the throttle valve and the EGR valve act synergistically to control the EGR working area. Therefore, the control of the EGR valve is realized through the cooperation of the VGT valve and the throttle valve under the condition of ensuring the advance of the air inflow, and the opening degrees of the VGT and the throttle valve are controlled according to the front-back pressure ratio of the EGR valve, so that the normal work of the EGR of the exhaust gas recirculation system is realized, and the EGR working area of the exhaust gas recirculation system is expanded. Meanwhile, the EGR of the exhaust gas recirculation system is external EGR, namely cold EGR, so that pumping loss can be reduced and engine knocking can be weakened, and therefore when the positive effect of the EGR on oil consumption is greater than the negative effect of the EGR on the oil consumption, the oil consumption can be further reduced. Meanwhile, the purpose of low oil consumption by enlarging the EGR working area can be achieved without additionally arranging control equipment, and the method is more economical and applicable.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a block diagram illustrating a method for controlling an EGR operating region of an exhaust gas recirculation system according to an exemplary embodiment of the present disclosure;
fig. 2 is a detailed flowchart of step S2;
fig. 3 is a detailed flowchart of step S3;
fig. 4 is a detailed flowchart of step S4.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all 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 application.
Referring to fig. 1, an embodiment of the present application provides a method for controlling an EGR operation region of an exhaust gas recirculation system, mainly including the following steps:
step S1: presetting parameter pulse spectrums under various working conditions of an engine;
step S2: constructing a torque model and an air quantity model according to the parameter pulse spectrum under the operating condition, and solving the required air inflow under the operating condition;
step S3: acquiring the actual rotating speed of an engine under the operating condition, determining the required front-to-back pressure ratio of the EGR valve according to the actual rotating speed and the required air inflow, and driving the VGT valve and the throttle valve to respond by adopting open-loop control;
step S4: acquiring an actual front-rear pressure ratio of the EGR valve under the operating condition, and controlling the opening degree of the VGT valve according to the required front-rear pressure ratio;
step S5: controlling the opening of the throttle valve according to the parameter pulse spectrum under the operating condition and the actual opening of the VGT valve;
step S6: and acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and a preset parameter pulse spectrum under an operation condition so as to enable the actual front-back pressure ratio of the EGR valve to approach the required front-back pressure ratio.
The embodiment of the application provides a control method for an EGR (exhaust gas recirculation) working area of an EGR (exhaust gas recirculation) system, under the premise of ensuring air inflow through the opening degrees of a VGT valve and a throttle valve, the opening degrees of the VGT valve and the throttle valve are controlled by taking the front-back pressure ratio of the EGR valve as a control target, and then the opening degree of the EGR valve is controlled, and the VGT valve, the throttle valve and the EGR valve act in a synergistic manner, so that the actual front-back pressure ratio of the EGR valve approaches to the required front-back pressure ratio, and further the EGR working area is controlled.
Therefore, the control of the EGR valve is realized through the cooperation of the VGT valve and the throttle valve under the condition of ensuring the advance of the air inflow, the opening degrees of the VGT and the throttle valve are controlled according to the front-back pressure ratio of the EGR valve, the limitation of the EGR working area of the exhaust gas recirculation system is avoided, and the EGR working area of the exhaust gas recirculation system is expanded.
Meanwhile, the EGR of the exhaust gas recirculation system is external EGR, namely cold EGR, so that pumping loss can be reduced and engine knocking can be weakened, and therefore when the positive effect of the EGR on oil consumption is greater than the negative effect of the EGR caused by the pressure drop of a throttle valve, the oil consumption can be further reduced. Meanwhile, the purpose of low oil consumption by enlarging the EGR working area can be achieved without additionally arranging control equipment, and the method is more economical and applicable.
Specifically, the parameters in the parameter pulse spectrum include a required torque, a friction loss, a pumping loss, an ignition efficiency, an air-fuel ratio efficiency, a combustion efficiency, a required front-to-back pressure ratio of the EFG valve, a charging efficiency, a VGT valve opening degree open-loop control amount, a throttle valve pressure drop open-loop control amount, a correspondence relationship between a throttle valve area and an opening degree of the throttle valve, and a required EGR rate.
As shown in fig. 2, preferably, the specific steps of step S2 are:
step S201: calculating to obtain a required total torque according to the required torque, friction loss, pumping loss, ignition efficiency and air-fuel ratio efficiency under a preset operation condition; wherein, the total torque is equal to the sum of the required torque, the friction loss and the pumping loss divided by the ignition efficiency and the air-fuel ratio efficiency;
step S202: dividing the required total torque by the combustion efficiency and the fuel calorific value of the actual oil product to obtain the required fuel quantity;
step S203: and determining the required air inflow according to the product of the required fuel quantity and the air-fuel ratio of the actual oil product.
As shown in fig. 3, preferably, the specific steps of step S3 are:
step S301: acquiring the actual rotating speed of the engine under the operating condition;
step S302: inquiring a preset parameter pulse spectrum under an operation condition according to the actual rotating speed and the required air inflow, and determining a required front-back pressure ratio of an EGR valve, a VGT valve opening open-loop control quantity and a throttle valve pressure drop open-loop control quantity which are preset under the operation condition;
step S303: and driving the VGT valve and the throttle valve to respond in a feedforward mode according to the opening open-loop control quantity of the VGT valve and the pressure drop open-loop control quantity of the throttle valve.
In this embodiment, preferably, the specific step of step S4 includes:
when the EGR working area is in a supercharging area, solving to obtain the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve according to the opening degree of the VGT valve; and
when the EGR working area is in a non-supercharging area, solving the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve to be zero.
When the EGR operation region is in the supercharging region, that is, in the medium-and-large load region, the engine needs to increase the intake pressure by controlling the opening degree of the VGT valve in the turbocharger VGT so as to satisfy the intake air amount, at this time, the opening degree amount of the VGT valve obtained by solving the front-to-back pressure ratio of the EGR valve is used to control the opening degree of the VGT valve, that is, the actual opening degree of the VGT valve is the opening degree amount.
When the EGR operation region is in the non-supercharging region, that is, in the small load region, the engine can satisfy the intake air amount by self-priming, and therefore, the solved result of the VGT valve is not directly used as the opening amount of the VGT valve, but zero is used as the opening amount of the VGT valve, that is, the actual opening amount of the VGT valve is zero.
As shown in fig. 4, when the EGR operation region is in the supercharging region, the specific steps of obtaining the opening degree of the VGT valve according to the actual front-rear pressure ratio of the EGR valve and the required front-rear pressure ratio, and controlling the opening degree of the VGT valve according to the opening degree of the VGT valve include:
step S401: solving the opening increment of the VGT valve according to the difference value of the required front-back pressure ratio and the actual front-back pressure ratio;
step S402: obtaining the opening amount of the VGT valve according to the sum of the opening increment of the VGT valve and the preset opening open-loop control amount of the VGT valve;
step S403: and controlling the opening degree of the VGT valve according to the opening degree control of the VGT valve.
Further, the specific steps of step S401 are:
and solving a proportional term, an integral term and a differential term of the difference value of the required front-back pressure ratio and the actual front-back pressure ratio with respect to time, respectively multiplying the difference value by a preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening increment of the VGT valve.
In the embodiment of the application, the difference between the required front-rear pressure ratio and the actual front-rear pressure ratio is used as an input quantity, a first closed-loop PID algorithm is adopted to solve and obtain the opening degree increment of the VGT valve, and then the previous opening degree of the VGT valve is adjusted to obtain the current actual opening degree of the VGT valve, namely the opening degree of the VGT valve is equal to the opening degree increment of the VGT valve plus the previous opening degree of the VGT valve. Wherein, the opening amount of the VGT valve is a parameter value corresponding to the opening of the VGT valve.
And the proportional term coefficient, the integral term coefficient and the differential term coefficient of the first closed-loop PID algorithm are preset values determined according to the working condition of the engine.
Preferably, the specific steps of step S5 are:
step S501: acquiring the front supercharging pressure of a throttle valve according to the actual opening of the VGT valve;
step S502: determining the required pressure behind a throttle valve according to the required air inflow under the operating condition of the engine and the preset inflation efficiency;
step S503: calculating the required area of the throttle according to the pressure drop of the supercharging pressure in front of the throttle and the required pressure behind the throttle;
step S505: and inquiring corresponding throttle opening amount in the corresponding relation between the preset throttle area and the throttle opening according to the required area of the throttle, and controlling the throttle opening according to the inquired throttle opening amount.
Preferably, the specific step of step S6 includes:
step S601: acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve;
step S602: according to the difference value between the actual EGR rate and the preset required EGR rate under the operation condition, solving a proportional term, an integral term and a differential term of the difference value with respect to time, respectively multiplying the difference value by a corresponding preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening amount of the EGR valve;
step S603: and controlling the opening degree of the EGR valve according to the opening degree of the EGR valve.
In this embodiment, when the opening degree of the valve of the EGR valve is controlled by using the second closed-loop PID algorithm to reach the expected value, the actual front-to-back pressure ratio of the EGR valve at that time is measured, and the difference between the actual front-to-back pressure ratio and the required front-to-back pressure ratio is used as an input quantity to continuously control the opening degree of the VGT valve by using the first closed-loop PID algorithm.
And the proportional term coefficient, the integral term coefficient and the differential term coefficient of the second closed-loop PID algorithm are preset values determined according to the working condition of the engine.
Preferably, the specific steps of step S1 are:
and calibrating the parameter pulse spectrum of the engine under each working condition according to the dynamic property, stability, oil consumption and emission conditions of the engine under each working condition.
In this embodiment, the parameter pulse spectrum MAP determines parameters under each operating condition, that is, a required torque, a friction loss, a pumping loss, an ignition efficiency, an air-fuel ratio efficiency, a combustion efficiency, a required front-to-back pressure ratio of the EFG valve, a charging efficiency, a VGT valve opening degree open-loop control amount, a throttle valve pressure drop open-loop control amount, a corresponding relationship between a throttle area and an opening degree of the throttle valve, a required EGR rate, and the like, according to a dynamic property, a stability, an oil consumption, and an emission condition of the engine under each operating condition, and fills the parameters into a corresponding calibration table to form the parameter pulse spectrum.
The embodiment of the present application further provides a control system for an EGR operation region of an exhaust gas recirculation system, where the control system includes:
a memory for storing executable instructions;
and the processor is connected with the memory and is used for operating the executable instructions to execute the control method of the EGR working area of the exhaust gas recirculation system.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; 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 meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or 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.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. 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 application. Thus, the present application 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 (9)

1. A method of controlling an EGR operating region of an exhaust gas recirculation system, the method comprising:
presetting parameter pulse spectrums under various working conditions of an engine;
constructing a torque model and an air quantity model according to the parameter pulse spectrum under the operating condition, and solving the required air inflow under the operating condition;
acquiring the actual rotating speed of an engine under the operating condition, determining the required front-to-back pressure ratio of the EGR valve according to the actual rotating speed and the required air inflow, and driving the VGT valve and the throttle valve to respond by adopting open-loop control;
acquiring an actual front-rear pressure ratio of the EGR valve under the operating condition, and controlling the opening degree of the VGT valve according to the required front-rear pressure ratio;
controlling the opening of the throttle valve according to the parameter pulse spectrum under the operating condition and the actual opening of the VGT valve;
acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and a preset parameter pulse spectrum under an operation condition so as to enable the actual front-back pressure ratio of the EGR valve to approach the required front-back pressure ratio;
the specific steps of obtaining the actual front-rear pressure ratio of the EGR valve under the operation working condition and controlling the opening degree of the VGT valve according to the required front-rear pressure ratio comprise:
when the EGR working area is in a supercharging area, solving to obtain the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve according to the opening degree of the VGT valve;
when the EGR working area is in a non-supercharging area, solving the opening degree of the VGT valve according to the actual front-back pressure ratio and the required front-back pressure ratio of the EGR valve, and controlling the opening degree of the VGT valve to be zero.
2. The method of controlling an EGR operating region of an exhaust gas recirculation system of claim 1 wherein the parameters in the parameter pulse spectrum comprise:
the control method comprises the steps of required torque, friction loss, pumping loss, ignition efficiency, air-fuel ratio efficiency, combustion efficiency, required front-back pressure ratio of an EFG valve, charging efficiency, VGT valve opening degree open-loop control quantity, throttle valve pressure drop open-loop control quantity, corresponding relation between throttle valve area and opening degree of a throttle valve and required EGR rate.
3. The method for controlling the EGR operating region of the exhaust gas recirculation system according to claim 2, wherein the steps of constructing the torque model and the air volume model according to the parameter pulse spectrum under the operating condition and solving the required air volume under the operating condition comprise:
calculating to obtain a required total torque according to the required torque, friction loss, pumping loss, ignition efficiency and air-fuel ratio efficiency under a preset operation condition;
dividing the required total torque by the combustion efficiency and the fuel calorific value of the actual oil product to obtain the required fuel quantity;
and determining the required air inflow according to the product of the required fuel quantity and the air-fuel ratio of the actual oil product.
4. The method of controlling an EGR operating region of an exhaust gas recirculation system according to claim 2, wherein the steps of determining a required pre-post pressure ratio of the EGR valve based on the actual rotation speed and the required intake air amount, and driving the VGT valve and the throttle valve in response using open-loop control comprise:
inquiring a preset parameter pulse spectrum under an operation condition according to the actual rotating speed and the required air inflow, and determining a required front-back pressure ratio of an EGR valve, a VGT valve opening open-loop control quantity and a throttle valve pressure drop open-loop control quantity which are preset under the operation condition;
and driving the VGT valve and the throttle valve to respond in a feedforward mode according to the opening open-loop control quantity of the VGT valve and the pressure drop open-loop control quantity of the throttle valve.
5. The method for controlling the EGR operation region of the exhaust gas recirculation system according to claim 4, wherein the specific steps of solving the opening amount of the VGT valve according to the actual pre-post pressure ratio and the required pre-post pressure ratio of the EGR valve when the EGR operation region is in the supercharging region, and controlling the opening amount of the VGT valve according to the opening amount of the VGT valve are as follows:
solving the opening increment of the VGT valve according to the difference value of the required front-back pressure ratio and the actual front-back pressure ratio;
obtaining the opening amount of the VGT valve according to the sum of the opening increment of the VGT valve and the preset opening open-loop control amount of the VGT valve;
and controlling the opening degree of the VGT valve according to the opening degree control of the VGT valve.
6. The method of controlling an EGR operating region of an exhaust gas recirculation system according to claim 5, wherein the step of solving for the increase in the opening degree of the VGT valve based on the difference between the required pre-post pressure ratio and the actual pre-post pressure ratio comprises the steps of:
and solving a proportional term, an integral term and a differential term of the difference value of the required front-back pressure ratio and the actual front-back pressure ratio with respect to time, respectively multiplying the difference value by a preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening increment of the VGT valve.
7. The method of controlling an EGR operating region of an exhaust gas recirculation system according to claim 2, wherein the controlling the opening degree of the throttle valve according to the parameter pulse spectrum under the operating condition and the actual opening degree of the VGT valve comprises:
acquiring the front supercharging pressure of a throttle valve according to the actual opening of the VGT valve;
determining the required pressure behind a throttle valve according to the required air inflow under the operating condition of the engine and the preset inflation efficiency;
calculating the required area of the throttle according to the pressure drop of the supercharging pressure in front of the throttle and the required pressure behind the throttle;
and inquiring corresponding throttle opening amount in the corresponding relation between the preset throttle area and the throttle opening according to the required area of the throttle, and controlling the throttle opening according to the inquired throttle opening amount.
8. The method for controlling the EGR operation region of the exhaust gas recirculation system according to claim 1, wherein the steps of obtaining the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve, and controlling the opening degree of the EGR valve according to the actual EGR rate and the preset parameter pulse spectrum under the operation condition comprise:
acquiring the actual EGR rate of the EGR of the exhaust gas recirculation system according to the opening degree of the VGT valve and the opening degree of the throttle valve;
according to the difference value between the actual EGR rate and the preset required EGR rate under the operation condition, solving a proportional term, an integral term and a differential term of the difference value with respect to time, respectively multiplying the difference value by a corresponding preset proportional term coefficient, an integral term coefficient and a differential term coefficient, and summing to obtain the opening amount of the EGR valve;
and controlling the opening degree of the EGR valve according to the opening degree of the EGR valve.
9. A control system for an EGR operating region of an exhaust gas recirculation system, the control system comprising:
a memory for storing executable instructions;
a processor coupled to the memory for executing the executable instructions to perform a method of controlling an EGR operating region of an exhaust gas recirculation system according to any of claims 1-8.
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