CN112746905A - Exhaust gas recirculation valve control method and system and vehicle - Google Patents
Exhaust gas recirculation valve control method and system and vehicle Download PDFInfo
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- CN112746905A CN112746905A CN201911055842.6A CN201911055842A CN112746905A CN 112746905 A CN112746905 A CN 112746905A CN 201911055842 A CN201911055842 A CN 201911055842A CN 112746905 A CN112746905 A CN 112746905A
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- 239000002912 waste gas Substances 0.000 claims description 7
- 230000000875 corresponding effect Effects 0.000 description 20
- 230000001276 controlling effect Effects 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 7
- 238000004364 calculation method Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
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- 230000001105 regulatory effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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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
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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]
- F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
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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]
- F02D41/0065—Specific aspects of external EGR control
- F02D41/0072—Estimating, calculating or determining the EGR rate, amount or flow
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
- F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
- F02M26/06—Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/65—Constructional details of EGR valves
- F02M26/66—Lift valves, e.g. poppet valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/65—Constructional details of EGR valves
- F02M26/70—Flap valves; Rotary valves; Sliding valves; Resilient valves
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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
- 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
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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
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/45—Sensors specially adapted for EGR systems
- F02M26/48—EGR valve position sensors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Engineering & Computer Science (AREA)
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- Combustion & Propulsion (AREA)
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- General Engineering & Computer Science (AREA)
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Abstract
The invention provides an exhaust gas recirculation valve control method, an exhaust gas recirculation valve control system and a vehicle, wherein the method comprises the following steps: acquiring the current load, the rotating speed and the air intake flow of the engine; determining a required exhaust gas recirculation rate of the engine according to the current load and the rotating speed; determining a required exhaust gas flow rate of the engine according to the intake air flow rate and the required exhaust gas recirculation rate; determining a current opening of an exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve; determining a target opening for the exhaust gas recirculation valve based on the requested exhaust gas flow, the current exhaust gas flow, and the current opening; adjusting the exhaust gas recirculation valve to the target opening. The target opening degree is calculated based on the required exhaust gas flow of the engine, the current exhaust gas flow of the exhaust gas recirculation valve and the current opening degree, and the required exhaust gas flow of the engine can be accurately matched.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a method and a system for controlling an exhaust gas recirculation valve and a vehicle.
Background
Currently, with the miniaturization of gasoline engines and the widespread use of supercharging technology, the problems of gasoline engine knocking and nitrogen oxide (abbreviated as NOx) emission are more severe.
External Exhaust Gas Recirculation (EGR) of a gasoline engine is a technical means for reducing NOx emission, suppressing knocking, and improving energy efficiency. The exhaust gas recirculation technology needs to arrange a cooler outside an engine, cool part of exhaust gas generated by the engine through the cooler, introduce the exhaust gas into an air inlet pipeline of the engine through an external loop, mix the exhaust gas and fresh air before entering a cylinder, and accurately control the exhaust gas recirculation rate through an exhaust gas recirculation valve.
However, in the conventional technology, the opening degree of the exhaust gas recirculation valve is merely mechanically matched with the exhaust gas recirculation rate, and when the target exhaust gas recirculation rate of the engine changes, the opening degree of the exhaust gas recirculation valve is adjusted to correspond to the target exhaust gas recirculation rate according to the matching relationship, so that the actual amount of exhaust gas flowing into the engine cannot be accurately matched with the exhaust gas recirculation rate actually required by the engine.
Disclosure of Invention
In view of the above, the present invention is directed to a method and a system for controlling an exhaust gas recirculation valve, and a vehicle, so as to solve the problem in the prior art that the control of the exhaust gas recirculation valve is not precise enough, so that the amount of exhaust gas flowing into an engine cannot be accurately matched with the actual demand of the engine.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
an exhaust gas recirculation valve control method applied to a vehicle, wherein the method comprises the following steps:
acquiring the current load, the rotating speed and the air intake flow of the engine;
determining a required exhaust gas recirculation rate of the engine according to the current load and the rotating speed;
determining a required exhaust gas flow rate of the engine according to the intake air flow rate and the required exhaust gas recirculation rate;
determining a current opening of an exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve;
determining a target opening for the exhaust gas recirculation valve based on the requested exhaust gas flow, the current exhaust gas flow, and the current opening;
adjusting the exhaust gas recirculation valve to the target opening.
Further, in the egr valve control method, the determining a current opening degree of the egr valve and a current flow rate of the exhaust gas flowing through the egr valve includes:
determining a current opening of an exhaust gas recirculation valve;
determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a pre-valve pressure and a post-valve pressure of the exhaust gas recirculation valve;
determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas;
determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure in combination with a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the valve port sound velocity flow in the standard state;
and determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the conversion coefficient and the valve port sound speed flow under the standard state.
Further, in the egr valve control method, the determining a current opening degree of the egr valve and a current flow rate of the exhaust gas flowing through the egr valve includes:
determining a current opening of an exhaust gas recirculation valve;
determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
and determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
Further, in the egr valve control method, the determining a target opening degree according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree includes:
and determining the target opening degree through a proportional-integral closed-loop regulation algorithm according to the required exhaust gas flow, the current exhaust gas flow and the current opening degree.
Further, in the exhaust gas recirculation valve control method, the adjusting the exhaust gas recirculation valve to the target opening degree includes:
determining a driving duty ratio and a driving direction aiming at the exhaust gas recirculation valve through a proportional-calculus closed-loop regulation algorithm according to the current opening and the target opening;
and controlling the exhaust gas recirculation valve to adjust to the target opening according to the driving duty ratio and the driving direction.
Another object of the present invention is to provide an egr valve control system applied to a vehicle, wherein the system comprises:
the first acquisition module is used for acquiring the current load, the rotating speed and the air intake flow of the engine;
a first determination module for determining a required exhaust gas recirculation rate of the engine based on the current load and the rotational speed;
a second determination module for determining a required exhaust gas flow rate of the engine based on the intake air flow rate and the required exhaust gas recirculation rate;
a third determination module for determining a current opening of an exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve;
a fourth determining module for determining a target opening for the exhaust gas recirculation valve based on the required exhaust gas flow, the current exhaust gas flow, and the current opening;
an adjustment module to adjust the exhaust gas recirculation valve to the target opening.
Further, in the egr valve control system, the third determining module may include:
a first opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
the first valve port flow area determining unit is used for determining the valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the first parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
the first determining unit is used for determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas;
the second determining unit is used for determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure in combination with a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the valve port sound velocity flow in the standard state;
and the third determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the multiplication of the conversion coefficient and the valve port sound speed flow in the standard state.
Further, in the egr valve control system, the third determining module may include:
a second opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
a second valve port flow area determination unit for determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the second parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
and the fourth determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
Further, in the egr valve control system, the fourth determining module is specifically configured to determine the target opening degree through a proportional-integral closed-loop adjustment algorithm according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree.
Further, in the egr valve control system, the adjusting module includes:
a fifth determining unit, configured to determine, according to the current opening and the target opening, a driving duty ratio and a driving direction for the exhaust gas recirculation valve through a proportional-derivative-integral closed-loop adjustment algorithm;
and the control unit is used for controlling the exhaust gas recirculation valve to be adjusted to the target opening according to the driving duty ratio and the driving direction.
Compared with the prior art, the control method and the control system of the exhaust gas recirculation valve have the following advantages:
firstly, determining the required exhaust gas recirculation rate of the engine according to the current load and the rotating speed of the engine; determining the required exhaust gas flow of the engine according to the air inlet flow of the engine and the required exhaust gas recirculation rate; determining the current opening of the exhaust gas recirculation valve and the current exhaust gas flow passing through the exhaust gas recirculation valve, and determining a target opening of the exhaust gas recirculation valve according to the required exhaust gas flow, the current exhaust gas flow and the current opening; the exhaust gas recirculation valve is then adjusted to the target opening. The method comprises the steps of determining the required exhaust gas flow of an engine, the current exhaust gas flow and the current opening degree of an exhaust gas recirculation valve in real time, determining the target opening degree of the exhaust gas recirculation valve, and adjusting the exhaust gas recirculation valve to the target opening degree.
It is a further object of the invention to propose a vehicle, wherein the vehicle comprises said egr valve control system.
The vehicle has the same advantages as the control method and the control system of the exhaust gas recirculation valve compared with the prior art, and the detailed description is omitted.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic flow chart illustrating a method for controlling an EGR valve according to an embodiment of the present invention;
FIG. 2 is a gas path block diagram of a gasoline engine having a high pressure external exhaust gas recirculation system in an embodiment of the present invention;
FIG. 3 is a gas path block diagram of a gasoline engine having a low pressure external exhaust gas recirculation system in an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a disc-rotating EGR valve according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a poppet-type EGR valve in accordance with an embodiment of the present invention;
FIG. 6 is a graph illustrating a transformation coefficient curve according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an egr valve control system according to an embodiment of the present invention.
Detailed Description
Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While embodiments of the present application are illustrated in the accompanying drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1, a schematic flow chart of a method for controlling an exhaust gas recirculation valve according to an embodiment of the present invention is shown, and the method is applied to a vehicle, and includes steps S100 to S600.
And S100, acquiring the current load, the rotating speed and the air intake flow of the engine.
In step S100, the required exhaust gas recirculation rate is different under different load and rotation speed conditions of the engine, wherein the exhaust gas recirculation rate is the ratio of the mass of the exhaust gas to the total mass of the gas entering the cylinder, that is, the amount of the exhaust gas required by the engine is determined by the load and rotation speed of the engine. Thus, it is desirable to determine the current load and speed of the engine, which can be determined directly from the current torque of the engine, and the speed of the engine, which can be determined using the vehicle's engine tachometer data.
In step S100, the intake air flow of the engine specifically refers to the fresh air flow entering the engine, because the required exhaust gas flow of the engine is determined by both the intake air flow and the exhaust gas recirculation rate of the engine. Under the same exhaust gas recirculation rate, the larger the intake air flow is, the larger the required exhaust gas flow of the engine is; the smaller the intake air flow rate, the smaller the required exhaust gas flow rate of the engine at the same exhaust gas recirculation rate.
In actual use, the intake air flow rate of the engine is also directly measured by an air flow meter provided at the engine intake pipe.
And S200, determining the required exhaust gas recirculation rate of the engine according to the current load and the rotating speed.
In the step S200, an exhaust gas recirculation rate table is queried according to the current load and the rotational speed of the engine obtained in the step S100 to obtain a required exhaust gas recirculation rate of the engine; the exhaust gas recirculation rate table is used for describing the corresponding relationship between the load and the rotational speed of the engine and the exhaust gas recirculation rate. When the engine works in the required exhaust gas recirculation rate state, the emission of NOx in the exhaust gas can be reduced to the minimum on the premise of meeting the current load and the current rotating speed. Considering that different engines require different exhaust gas recirculation rates under different load and rotating speed conditions, a corresponding relation table of the load, the rotating speed and the exhaust gas recirculation rate of the engine needs to be established through experiments, namely the exhaust gas recirculation rate table, two variables in the table are the load and the rotating speed, and an output value is the exhaust gas recirculation rate.
And step S300, determining the required exhaust gas flow of the engine according to the intake air flow and the required exhaust gas recirculation rate.
In step S300, since the exhaust gas recirculation rate is the ratio of the mass of exhaust gas to the mass of total gas entering the cylinder, the required exhaust gas flow rate of the engine can be determined according to the intake air flow rate and the required exhaust gas recirculation rate.
Specifically, the required exhaust gas flow rate may be calculated using the following equation (1):
step S400, determining a current opening of the exhaust gas recirculation valve and a current exhaust gas flow rate through the exhaust gas recirculation valve.
Because the temperature and pressure of the exhaust gas change in real time during the actual operation of the engine, the opening degree of the exhaust gas recirculation valve is not always proportional to the flow rate of the exhaust gas flowing through the exhaust gas recirculation valve, i.e., the current flow rate flowing through the exhaust gas recirculation valve cannot be directly determined by the current opening degree of the exhaust gas recirculation valve. However, under the same temperature and pressure conditions, the flow rate of the exhaust gas flowing through the exhaust gas recirculation valve is in a proportional relationship with the opening degree of the exhaust gas recirculation valve, i.e., the larger the opening degree, the larger the flow rate of the exhaust gas. Therefore, under the same temperature and pressure conditions, the exhaust gas flowing through the exhaust gas recirculation valve can be adjusted from the current exhaust gas flow rate to the required flow rate by adjusting the opening degree of the exhaust gas recirculation valve.
Wherein the opening degree of the exhaust gas recirculation valve is the proportion of the current position of the valve to the maximum stroke of the valve. The current opening of the egr valve may be obtained by monitoring the valve position of the egr valve by a position sensor.
The current exhaust gas flow rate can be determined, for example, by providing an exhaust gas flow meter at the exhaust gas recirculation valve, by which the exhaust gas flow rate through the exhaust gas recirculation valve is monitored. Of course, the magnitude of the exhaust gas flow rate may also be calculated according to a flow rate calculation formula according to a valve port flow area, a valve port flow rate coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure, and a valve rear pressure of the exhaust gas recirculation valve.
Step S500, determining a target opening degree aiming at the exhaust gas recirculation valve according to the required exhaust gas flow, the current exhaust gas flow and the current opening degree.
Since the exhaust gas flow rate flowing through the exhaust gas recirculation valve is positively correlated with the opening degree of the exhaust gas recirculation valve under the same temperature and pressure conditions, the target opening degree for the exhaust gas recirculation valve can be determined according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree.
Optionally, the step S500 includes the step S501:
and determining the target opening degree through a proportional-integral closed-loop regulation algorithm according to the required exhaust gas flow, the current exhaust gas flow and the current opening degree.
In step S501, the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree are input to a proportional-integral closed-loop adjustment algorithm, and the proportional-integral closed-loop adjustment algorithm is calculated by using the existing proportional-integral closed-loop adjustment principle.
Specifically, the required exhaust gas flow is used as a reference value, the opening degree regulating quantity is calculated through proportional-integral closed-loop regulation according to the difference value between the required exhaust gas flow and the current exhaust gas flow, and the target opening degree of the exhaust gas recirculation valve is accurately calculated by combining the current opening degree.
In practical applications, the step S501 may be implemented by a proportional integral controller.
And step S600, adjusting the exhaust gas recirculation valve to the target opening degree.
In step S600, at the same time, because the exhaust gas flow passing through the exhaust gas recirculation valve is positively correlated to the opening of the exhaust gas recirculation valve under the same temperature and pressure conditions, the exhaust gas flowing through the exhaust gas recirculation valve can be adjusted from the current exhaust gas flow to the required flow by adjusting the opening of the exhaust gas recirculation valve to the target opening, that is, the current combustion demand of the engine is satisfied.
Optionally, the step S600 includes steps S601 to S602:
and S601, determining a driving duty ratio and a driving direction of the exhaust gas recirculation valve according to the current opening and the target opening and through a proportional-derivative-integral closed-loop regulation algorithm.
In step S601, the driving direction is determined according to the difference between the current opening and the target opening, and the difference between the current opening and the target opening is input to a proportional-integral-derivative closed-loop adjustment algorithm, which calculates according to a proportional-integral-derivative closed-loop adjustment principle, and can calculate the driving duty ratio of the driving motor for driving and adjusting the opening of the exhaust gas recirculation valve. Specifically, the required target opening degree is used as a reference value, and the driving duty ratio is calculated through proportional-integral-derivative closed-loop regulation according to the difference between the target opening degree and the current opening degree.
In practical applications, the step S601 can be implemented by a proportional-micro-integral controller.
And step S602, controlling the exhaust gas recirculation valve to adjust to the target opening according to the driving duty ratio and the driving direction.
In step S602, the drive motor is controlled to adjust the opening degree of the egr valve until the opening degree of the egr valve is adjusted to the target opening degree, using the drive duty determined in step S601, that is, the drive direction.
In the embodiment of the invention, under the condition of combining the step S501 and the steps S601-S602, whether the current opening is adjusted to the target opening or not can be detected through a proportional-integral closed-loop adjusting algorithm, real-time tracking adjustment is carried out through a proportional-calculus closed-loop adjusting algorithm, and the accurate control of the exhaust gas recirculation rate is realized through the double closed-loop control mode.
Compared with the prior art, the control method of the exhaust gas recirculation valve has the following advantages:
the method comprises the steps of determining the required exhaust gas flow of an engine, the current exhaust gas flow and the current opening degree of an exhaust gas recirculation valve in real time, determining the target opening degree of the exhaust gas recirculation valve, and adjusting the exhaust gas recirculation valve to the target opening degree, wherein the target opening degree is obtained by calculation based on the required exhaust gas flow of the engine, the current exhaust gas flow of the exhaust gas recirculation valve and the current opening degree, so that the required exhaust gas flow of the engine can be accurately matched, and the problem that in the prior art, the control on the exhaust gas recirculation valve is not accurate enough, and the amount of exhaust gas flowing into the engine cannot be accurately matched with the actual requirement of the engine.
The control method of the exhaust gas recirculation valve provided by the embodiment of the invention is applied to vehicles, in particular to an engine of the vehicle, wherein the engine is a gasoline engine provided with an external exhaust gas recirculation system. The external exhaust gas recirculation system can be divided into a high-pressure external exhaust gas recirculation system and a low-pressure external exhaust gas recirculation system according to the difference between the exhaust gas taking position and the exhaust gas and fresh air mixing position.
Referring to fig. 2, a gas path structure diagram of a gasoline engine with a high-pressure external exhaust gas recirculation system is shown, and as shown in fig. 2, the gas path structure of the gasoline engine comprises an intake pipe 1, a compressor 2, a compressed gas intercooler 3, a throttle valve 4, an intake manifold 5, an engine 6, an exhaust manifold 7, an exhaust manifold 8, a turbine 13, a catalyst 11 and an exhaust line 12 which are sequentially connected through pipelines, and an exhaust gas recirculation valve intercooler 10 and an exhaust gas recirculation valve 9 are sequentially connected between the exhaust manifold 8 and the intake manifold 5 through pipelines.
In fig. 2, air enters a compressed air intercooler 3 through an air inlet pipe 2 under the action of an air compressor 1, and then reaches an air inlet manifold 5 through a throttle valve 4; meanwhile, the exhaust gas generated by the combustion of the engine 6 is discharged through the exhaust manifold 7 and then is converged in the exhaust manifold 8, and a part of the exhaust gas in the exhaust manifold 8 is cooled through an intercooler 10 of an exhaust gas recirculation valve, then passes through an exhaust gas recirculation valve 9, is mixed with the air passing through the throttle valve 4, then enters the intake manifold 5 and then enters the engine, so as to meet the combustion requirement of the engine and reduce the emission of NOx; and the other part of the exhaust gas in the exhaust manifold 8 enters the catalyst 11 for catalytic treatment after being acted by the turbine 13, and then enters the exhaust pipeline and is discharged outside.
Referring to fig. 3, a gas path block diagram of a gasoline engine having a low pressure external exhaust gas recirculation system is shown. As shown in fig. 3, the gas path structure of the gasoline engine includes an intake pipe 1, a compressor 2, a compressed gas intercooler 3, a throttle valve 4, an intake manifold 5, an engine 6, an exhaust manifold 7, an exhaust manifold 8, a turbine 13, a catalyst 11, and an exhaust pipe 12, which are sequentially connected by pipes, and an exhaust gas recirculation valve intercooler 10 and an exhaust gas recirculation valve 9 are sequentially connected between the turbine 13 and the compressor 1 by pipes.
In fig. 3, exhaust gas generated by combustion of an engine 6 is discharged through an exhaust manifold 7 and then joins an exhaust manifold 8, and then is treated by a turbine 13, a part of the exhaust gas is cooled by an exhaust gas recirculation valve intercooler 10 and then reaches an air inlet pipe through an exhaust gas recirculation valve 9, then enters a compressed gas intercooler 3 under the action of an air compressor 1, then reaches an air inlet manifold 5 through a throttle valve 4, and then enters the engine to meet the combustion requirement of the engine and reduce the emission of NOx; and the other part of the exhaust gas treated by the turbine 13 enters the catalytic converter 11 for catalytic treatment after being acted by the turbine 13, and then enters the exhaust pipeline and is discharged outside.
In both fig. 2 and fig. 3, the exhaust gas recirculation rate, which is the ratio of the mass of exhaust gas entering the engine intake manifold side 5 to the total mass of gas entering the cylinder, is controlled by controlling the opening size of the exhaust gas recirculation valve 9.
In a preferred embodiment of the present invention, the method for controlling an exhaust gas recirculation valve includes steps S201 to S209.
And step S201, acquiring the current load, the rotating speed and the air intake flow of the engine.
The above step S201 can refer to the detailed description of step S100, and is not repeated here.
And step S202, determining the required exhaust gas recirculation rate of the engine according to the current load and the rotating speed.
The above step S202 can refer to the detailed description of step S200, and is not repeated here.
And S203, determining the required exhaust gas flow of the engine according to the intake air flow and the required exhaust gas recirculation rate.
The above step S203 can refer to the detailed description of step S300, which is not repeated herein.
And step S204, determining the current opening of the exhaust gas recirculation valve.
In step S204, reference may be made to the detailed description of the current opening in step S400, which is not described herein again.
And S205, determining the valve port flow area of the exhaust gas recirculation valve according to the current opening.
In step S205, the valve port flow area is the actual area of the egr valve through which the exhaust gas flows, and is determined by the pipe size and the opening of the egr valve. Because the pipe size of the exhaust gas recirculation valve is fixed, the valve port flow area of the exhaust gas recirculation valve can be determined by the current opening degree of the exhaust gas recirculation valve.
In practical applications, the exhaust gas recirculation valve according to the embodiment of the present invention may be a disc rotating exhaust gas recirculation valve or a poppet exhaust gas recirculation valve.
The structure of the disc-type rotating egr valve is shown in fig. 4, and includes a valve pipe 41 and a disc valve plate 42 disposed in the valve pipe 41, wherein the disc valve plate 42 can rotate relative to the valve pipe 41; when the valve is fully opened, the disc valve plate 42 rotates until the plane of the disc valve plate 42 is the same as the valve pipe 41; when the valve is completely closed, the disc valve plate 42 rotates to a position where the plane of the disc valve plate 42 is perpendicular to the direction of the valve pipe 41. For the disc rotary type exhaust gas recirculation valve, the opening degree is the ratio of the included angle α between the disc valve plate 42 and the cross section direction of the valve pipe 41 to the disc valve plate 90 °, so the opening degree of the exhaust gas recirculation valve can be obtained by measuring the opening angle of the disc valve plate 42.
Specifically, for a disc rotary type exhaust gas recirculation valve, the valve port flow area a is calculated by the formula (2):
in the formula (2), d is the diameter of the disc valve plate 42.
The poppet type egr valve has a structure as shown in fig. 5, and includes a valve pipe 51 and a poppet valve plate 52 provided at an end of the valve pipe 51, wherein the poppet valve plate 52 is extendable and retractable with respect to the valve pipe 51; when the poppet valve plate 52 is separated from the end of the valve tube 51, the valve is opened; when the poppet plate 52 contacts the end of the valve tube 51, the valve is closed. For the poppet-type egr valve, the opening degree is the ratio of the displacement of the poppet valve plate 52 relative to the valve pipe 51 to the maximum displacement of the poppet valve plate, and the opening degree of the egr valve can be obtained by measuring the distance between the poppet valve plate 52 and the end of the valve pipe 51.
Specifically, for a poppet-type exhaust gas recirculation valve, the valve port flow area a is calculated by the equation (3):
a ═ pi d × h × current opening degree (3)
In the formula (3), d is the poppet valve plate 52 diameter, and h is the poppet valve plate 52 maximum displacement.
And S206, acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve.
In step S206, the valve port flow coefficient is a physical constant of the exhaust gas recirculation valve, the specific heat ratio and the exhaust gas density of the exhaust gas are determined by the current combustion exhaust gas of the engine, and the current exhaust gas can be detected, and the pre-valve pressure and the post-valve pressure of the exhaust gas recirculation valve are detected by the pressure sensor.
Step S207, determining the current exhaust gas flow flowing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
In step S207, the current exhaust gas flow of the flow exhaust gas recirculation valve is obtained according to a preset flow algorithm by using the obtained valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure. Concretely, the obtained valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the valve front pressure and the valve back pressure are substituted into the formula (A)4) Calculating to obtain the current exhaust gas flow M flowing through the exhaust gas recirculation valvecatEx：
In the formula (4), CDIs valve port flow coefficient, A is valve port flow area, gamma is waste gas specific heat ratio, P2Is the pressure behind the valve, P, of an exhaust gas recirculation valve1Is the pre-valve pressure of the exhaust gas recirculation valve.
In practical use, considering that γ changes very little, γ may be calculated as a fixed value, and may be 1.4.
And S208, determining a target opening degree of the exhaust gas recirculation valve according to the required exhaust gas flow, the current exhaust gas flow and the current opening degree.
The above step S208 can refer to the detailed description of step S500, and is not repeated here.
And step S209, adjusting the exhaust gas recirculation valve to the target opening degree.
The above step S209 can refer to the detailed description of step S600, which is not repeated herein.
Compared with the prior art, the control method of the exhaust gas recirculation valve has the following advantages that:
the required exhaust gas flow of the engine can be accurately matched by determining the required exhaust gas flow and the current opening of the engine, calculating the current exhaust gas flow of the exhaust gas recirculation valve by using a preset flow algorithm in real time, determining the target opening of the exhaust gas recirculation valve, and adjusting the exhaust gas recirculation valve to the target opening. The embodiment of the invention solves the problem that the control on the exhaust gas recirculation valve is not accurate enough in the prior art, so that the amount of the exhaust gas flowing into the engine cannot be accurately matched with the actual requirement of the engine, meanwhile, the exhaust gas flow is not required to be calculated by using an exhaust gas flowmeter, the cost of an engine electric control system is reduced, and the failure rate of the engine electric control system is reduced.
In another preferred embodiment of the present invention, the egr valve control method includes steps S301 to S315.
And S301, acquiring the current load, the rotation speed and the air intake flow of the engine.
The above step S301 can refer to the detailed description of step S100, and is not repeated here.
And step S302, determining the required exhaust gas recirculation rate of the engine according to the current load and the rotating speed.
The above step S302 can refer to the detailed description of step S200, and is not repeated here.
And step S303, determining the required exhaust gas flow of the engine according to the intake air flow and the required exhaust gas recirculation rate.
The above step S303 can refer to the detailed description of step S300, which is not repeated herein.
Step S304, determining the current opening of the exhaust gas recirculation valve.
In the above step S304, reference may be made to the detailed description of the current opening in the step S400, which is not described herein again.
And S305, determining the valve port flow area of the exhaust gas recirculation valve according to the current opening.
The above step S305 can refer to the detailed description of step S205, and is not repeated herein.
And S306, acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a pre-valve pressure and a post-valve pressure of the exhaust gas recirculation valve.
In step S306, the valve port flow coefficient is a physical constant of the exhaust gas recirculation valve, the exhaust gas specific heat ratio is determined by the current engine combustion exhaust gas, and the current exhaust gas can be detected, and the pre-valve pressure and the post-valve pressure of the exhaust gas recirculation valve are measured by the pressure sensor.
And S307, determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas.
Under the standard state, the sound velocity flow M of the valve portsonicCan be calculated by using the formula (5):
in the formula (5), CDIs valve port flow coefficient, A is valve port flow area, gamma is exhaust gas specific heat ratio in standard state, rho0Kneading is the exhaust gas density, p, in the standard state0Is the exhaust gas pressure in the standard state.
In the above step S307, the standard state means a standard atmospheric pressure of 1013kPa and a temperature of 0 ℃.
From equation (5), it can be seen that under the standard condition, for the same engine, under the same operating condition, CD、γ、ρ0、p0All of which are constants, and the sound velocity flow of the valve port of the exhaust gas generated by the engine is only related to the flow area of the valve port. Therefore, after the flow area of the valve port is determined, the sound velocity flow M of the valve port can be quickly calculatedsonic。
Step S308, determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure and by combining a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; and the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the sound speed flow of the valve port in the standard state.
In the above step S308, the correspondence relationship between the ratio between the valve rear pressure of the exhaust gas recirculation valve and the valve front pressure of the exhaust gas recirculation valve and the conversion coefficient is established in advance; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the valve port sound velocity flow in the standard state, and specifically, the conversion coefficient is the ratio of the actual flow passing through the exhaust gas recirculation valve to the valve port sound velocity flow in the standard state.
In step S308, the preset association relationship needs to be determined first. In order to determine the predetermined relationship, a function CUV of the ratio between the pressure after the valve and the pressure before the valve is designed, wherein the function CUV is as shown in formula (6):
in the formula (6), gamma is the specific heat ratio of the exhaust gas, P2Is the pressure behind the valve, P, of an exhaust gas recirculation valve1Is the pre-valve pressure of the exhaust gas recirculation valve.
It can be seen that the function CUV is
A function of, and McatEx＝CUV×Msonic. Considering that the electronic control unit of the vehicle has low operation efficiency and poor calculation accuracy, and the function CUV has an exponentiation operation process, the function CUV needs to be discretized, so as to reduce the operation amount of the electronic control unit on the premise that the calculation accuracy meets the preset requirement. The discretization process comprises the following specific steps:
note the book
Q is greater than or equal to 0 and Q is less than or equal to 1, n Q values are preset and are marked as Q1、Q2、Q3、…、QnSubstituting the Q values into the function CUV in sequence for calculation to obtain the CUV correspondingly1、CUV2、CUV3、…、CUVnA value; is expressed by the above-mentioned n Q values and n CUV values
The function CUV of (c) corresponds to the approximate shape of the curve. Note Q1、Q2、Q3、…、QnIn any adjacent Qa-1Value and QaValue, corresponding to a CUV value of CUVa-1And CUVaWherein a is less than or equal to n; for being at Qa-1Value and QaQ values between the values, setting the corresponding CUV values approximately to pass through (Q)a-1，CUVa-1) And (Q)a，CUVa) The vertical coordinate values corresponding to the line segments of the two points are any adjacent Qa-1Value and QaThe line segments between the values are connected to obtain a broken line, namely a conversion coefficient curve cur after discretization processing of the function CUV, wherein the conversion coefficient curve cur expresses a preset incidence relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient.
For any in [0,1 ]]In between
The value can be used for quickly calculating the corresponding cur value according to the conversion coefficient curve cur, and the corresponding cur value is the conversion coefficient.
Specifically, γ can be set to 1.4, n can be set to 14, and the corresponding Q1Is 0, Q2Is 0.5282, Q3Is 0.5283, Q4Is 0.55, Q5Is 0.6, Q6Is 0.65, Q7Is 0.7, Q8Is 0.75, Q9Is 0.8, Q10Is 0.85, Q11Is 0.9, Q12Is 0.95, Q13Is 0.99, Q14At 1, substituting function CUV to obtain corresponding CUV values 1, 0.396256618, 0.395845605, 0.391733364, 0.383037147, 0.369396547, 0.350205234, 0.324456608, 0.290393028, 0.244549111, 0.178033044, 0.081401448 and 0 in sequence, so as to obtain the value P2/P1Is 14 points (Q, CUV) on the coordinate axis with the abscissa and CUV as the ordinate, and then each adjacent point (Q, CUV) is connected to obtain the conversion coefficient curve cur, as shown in fig. 6.
Step S309, determining the current exhaust gas flow flowing through the exhaust gas recirculation valve according to the conversion coefficient and the valve port sound velocity flow in the standard state.
In the step S309, the conversion coefficient may be multiplied by the valve port sound velocity flow rate in the standard state to obtain the current exhaust gas flow rate flowing through the exhaust gas recirculation valve. That is, in step S309, M is addedcatEx＝CUV×MsonicThe discretization is calculated asMcatEx＝cur×MsonicThen, the sound velocity flow M of the valve port obtained in step S307 is combinedsonicAnd the cur value obtained in step S308, that is, the current exhaust gas flow rate flowing through the exhaust gas recirculation valve can be obtained.
Step S310 determines a target opening degree for the exhaust gas recirculation valve according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree.
The above step S310 can refer to the detailed description of step S500, and is not repeated herein.
Step S311 is to adjust the exhaust gas recirculation valve to the target opening degree.
The step S311 can refer to the detailed description of the step S600, and is not repeated herein.
Compared with the prior art, the control method of the exhaust gas recirculation valve has the following advantages that:
the method comprises the steps of determining a preset incidence relation between a ratio of a valve back pressure to a valve front pressure and a conversion coefficient, wherein the conversion coefficient is used for representing a corresponding relation between an actual flow passing through the exhaust gas recirculation valve and a valve port sound velocity flow in a standard state, determining the conversion coefficient according to the valve front pressure and the valve back pressure in real time and combining the preset incidence relation, further calculating the current exhaust gas flow of the exhaust gas recirculation valve, determining a target opening by combining the required exhaust gas flow of an engine and the current opening, and then adjusting the exhaust gas recirculation valve to the target opening. The embodiment of the invention not only solves the problem that the control on the exhaust gas recirculation valve is not accurate enough in the prior art, so that the amount of the exhaust gas flowing into the engine can not be accurately matched with the actual requirement of the engine, but also does not need to utilize an exhaust gas flowmeter to calculate the flow of the exhaust gas, simplifies the complexity of a control algorithm and improves the operation efficiency.
Another objective of the present invention is to provide an egr valve control system for a vehicle, wherein referring to fig. 7, fig. 7 shows a schematic structural diagram of an egr valve control system according to an embodiment of the present invention, the system includes:
the first acquisition module 71 is used for acquiring the current load, the rotating speed and the air intake flow of the engine;
a first determination module 72 for determining a required exhaust gas recirculation rate of the engine based on the current load and speed;
a second determination module 73 for determining a required exhaust gas flow rate of the engine based on the intake air flow rate and the required exhaust gas recirculation rate;
a third determination module 74 for determining a current opening of the exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve;
a fourth determining module 75, configured to determine a target opening degree for the exhaust gas recirculation valve according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree;
an adjustment module 76 adjusts the exhaust gas recirculation valve to the target opening.
In the system according to the embodiment of the present invention, the required exhaust gas flow rate of the engine is determined in real time by the second determining module 72, the current exhaust gas flow rate and the current opening degree of the exhaust gas recirculation valve are determined in real time by the third determining module 74, the target opening degree for the exhaust gas recirculation valve is determined by the fourth determining module 75, and then the exhaust gas recirculation valve is adjusted to the target opening degree by the adjusting module 76.
Optionally, in the egr valve control system, the third determining module 74 includes:
a first opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
the first valve port flow area determining unit is used for determining the valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the first parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
the first determining unit is used for determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas;
the second determining unit is used for determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure in combination with a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the sound speed flow of the valve port in a standard state;
and the third determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the conversion coefficient and the valve port sound speed flow in the standard state.
Optionally, in the egr valve control system, the third determining module 74 includes:
a second opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
a second valve port flow area determination unit for determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the second parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
and the fourth determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
Optionally, in the exhaust gas recirculation valve control system, the fourth determining module 75 is specifically configured to determine the target opening degree through a proportional-integral closed-loop adjusting algorithm according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree.
Optionally, in the egr valve control system, the adjusting module 76 includes:
a fifth determining unit, configured to determine, according to the current opening and the target opening, a driving duty ratio and a driving direction for the exhaust gas recirculation valve through a proportional-derivative-integral closed-loop adjustment algorithm;
and the control unit is used for controlling the exhaust gas recirculation valve to be adjusted to the target opening according to the driving duty ratio and the driving direction.
It is a further object of the invention to propose a vehicle, wherein the vehicle comprises said egr valve control system.
The vehicle has the same advantages as the control method and the control system of the exhaust gas recirculation valve compared with the prior art, and the detailed description is omitted
Technical details and benefits regarding the above-described system and vehicle have been set forth in the above-described method and will not be described in detail herein.
In summary, according to the exhaust gas recirculation valve control method, the exhaust gas recirculation valve control system and the vehicle provided by the application, the required exhaust gas recirculation rate of the engine is determined according to the current load and the rotating speed of the engine; determining the required exhaust gas flow of the engine according to the air inlet flow of the engine and the required exhaust gas recirculation rate; determining the current opening of the exhaust gas recirculation valve and the current exhaust gas flow passing through the exhaust gas recirculation valve, and determining a target opening of the exhaust gas recirculation valve according to the required exhaust gas flow, the current exhaust gas flow and the current opening; the exhaust gas recirculation valve is then adjusted to the target opening. The method comprises the steps of determining the required exhaust gas flow of an engine, the current exhaust gas flow and the current opening degree of an exhaust gas recirculation valve in real time, determining the target opening degree of the exhaust gas recirculation valve, and adjusting the exhaust gas recirculation valve to the target opening degree.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. An exhaust gas recirculation valve control method applied to a vehicle, characterized by comprising:
acquiring the current load, the rotating speed and the air intake flow of the engine;
determining a required exhaust gas recirculation rate of the engine according to the current load and the rotating speed;
determining a required exhaust gas flow rate of the engine according to the intake air flow rate and the required exhaust gas recirculation rate;
determining a current opening of an exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve;
determining a target opening for the exhaust gas recirculation valve based on the requested exhaust gas flow, the current exhaust gas flow, and the current opening;
adjusting the exhaust gas recirculation valve to the target opening.
2. The exhaust gas recirculation valve control method of claim 1, wherein determining a current opening of the exhaust gas recirculation valve and a current flow rate of exhaust gas flowing through the exhaust gas recirculation valve comprises:
determining a current opening of an exhaust gas recirculation valve;
determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a pre-valve pressure and a post-valve pressure of the exhaust gas recirculation valve;
determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas;
determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure in combination with a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the valve port sound velocity flow in the standard state;
and determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the conversion coefficient and the valve port sound speed flow in the standard state.
3. The exhaust gas recirculation valve control method of claim 1, wherein determining a current opening of the exhaust gas recirculation valve and a current flow rate of exhaust gas flowing through the exhaust gas recirculation valve comprises:
determining a current opening of an exhaust gas recirculation valve;
determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
and determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
4. The exhaust gas recirculation valve control method of claim 1, wherein said determining a target opening based on said requested exhaust gas flow rate, said current exhaust gas flow rate, and said current opening comprises:
and determining the target opening degree through a proportional-integral closed-loop regulation algorithm according to the required exhaust gas flow, the current exhaust gas flow and the current opening degree.
5. The exhaust gas recirculation valve control method of any of claims 1-4, wherein said adjusting the exhaust gas recirculation valve to the target opening comprises:
determining a driving duty ratio and a driving direction aiming at the exhaust gas recirculation valve through a proportional-calculus closed-loop regulation algorithm according to the current opening and the target opening;
and controlling the exhaust gas recirculation valve to adjust to the target opening according to the driving duty ratio and the driving direction.
6. An exhaust gas recirculation valve control system for a vehicle, the system comprising:
the first acquisition module is used for acquiring the current load, the rotating speed and the air intake flow of the engine;
a first determination module for determining a required exhaust gas recirculation rate of the engine based on the current load and the rotational speed;
a second determination module for determining a required exhaust gas flow rate of the engine based on the intake air flow rate and the required exhaust gas recirculation rate;
a third determination module for determining a current opening of an exhaust gas recirculation valve and a current exhaust gas flow through the exhaust gas recirculation valve;
a fourth determining module for determining a target opening for the exhaust gas recirculation valve based on the required exhaust gas flow, the current exhaust gas flow, and the current opening;
an adjustment module to adjust the exhaust gas recirculation valve to the target opening.
7. The EGR valve control system of claim 6, wherein the third determination module comprises:
a first opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
the first valve port flow area determining unit is used for determining the valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the first parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
the first determining unit is used for determining the sound velocity flow of the valve port in a standard state according to the flow area of the valve port, the flow coefficient of the valve port and the specific heat ratio of the waste gas;
the second determining unit is used for determining a conversion coefficient according to the pre-valve pressure and the post-valve pressure in combination with a preset incidence relation; the preset incidence relation is used for representing the corresponding relation between the ratio of the pressure after the valve to the pressure before the valve and the conversion coefficient; the conversion coefficient is used for representing the corresponding relation between the actual flow passing through the exhaust gas recirculation valve and the valve port sound velocity flow in the standard state;
and the third determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the conversion coefficient and the valve port sound speed flow in the standard state.
8. The EGR valve control system of claim 6, wherein the third determination module comprises:
a second opening degree determination unit for determining a current opening degree of the exhaust gas recirculation valve;
a second valve port flow area determination unit for determining a valve port flow area of the exhaust gas recirculation valve according to the current opening degree;
the second parameter acquisition unit is used for acquiring a valve port flow coefficient, an exhaust gas specific heat ratio, an exhaust gas density, a valve front pressure and a valve rear pressure of the exhaust gas recirculation valve;
and the fourth determining unit is used for determining the current exhaust gas flow passing through the exhaust gas recirculation valve according to the valve port flow coefficient, the valve port flow area, the exhaust gas specific heat ratio, the exhaust gas density, the pre-valve pressure and the post-valve pressure.
9. The egr valve control system of claim 6, wherein the fourth determination module is specifically configured to determine the target opening degree through a proportional-integral closed-loop regulation algorithm according to the required exhaust gas flow rate, the current exhaust gas flow rate, and the current opening degree.
10. The EGR valve control system of any of claims 6-9, wherein the adjustment module comprises:
a fifth determining unit, configured to determine, according to the current opening and the target opening, a driving duty ratio and a driving direction for the exhaust gas recirculation valve through a proportional-derivative-integral closed-loop adjustment algorithm;
and the control unit is used for controlling the exhaust gas recirculation valve to be adjusted to the target opening according to the driving duty ratio and the driving direction.
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| CN115163315A (en) * | 2022-06-28 | 2022-10-11 | 东风汽车集团股份有限公司 | Exhaust gas recirculation control device, control method and storage medium |
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