CN121205801A - Method, apparatus and medium for controlling injection of mixed fuel engine - Google Patents
Method, apparatus and medium for controlling injection of mixed fuel engineInfo
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- CN121205801A CN121205801A CN202511750658.9A CN202511750658A CN121205801A CN 121205801 A CN121205801 A CN 121205801A CN 202511750658 A CN202511750658 A CN 202511750658A CN 121205801 A CN121205801 A CN 121205801A
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Abstract
The application discloses a mixed fuel engine injection control method, equipment and medium, relating to the technical field of engine control, wherein the method comprises the steps of obtaining a target air-fuel ratio and an actual air-fuel ratio; the method comprises the steps of calculating a first deviation of a target air-fuel ratio and an actual air-fuel ratio, inputting a first calculation array corresponding to a current operation condition, a last second deviation and a mixed fuel injection adjustment coefficient in a last preset step length into a combustion adjustment transmission model to obtain a second deviation, inputting the second calculation array corresponding to the current operation condition, the first deviation and the second deviation into a control model to obtain the mixed fuel injection adjustment coefficient, and obtaining the injection quantity of the mixed fuel based on the mixed fuel injection adjustment coefficient under the condition that an engine control mode is determined to be in a closed-loop control state. The application is used for solving the problems of poor running stability and safety of the engine during multi-fuel combustion in the prior art and realizing safe and accurate control of the engine.
Description
Technical Field
The application relates to the technical field of engine control, in particular to a mixed fuel engine injection control method, mixed fuel engine injection control equipment and mixed fuel engine injection control medium.
Background
As the carbon neutralization concept goes deep, the type of fuel used for engine combustion gradually transitions from a single high carbon fuel to a low or zero carbon fuel, thereby promoting engine blending fuel demand. However, there are significant differences in the physicochemical properties of different fuels, such as that some fuels are energy intensive on a single mass basis, but poor combustion conditions are easily generated due to the high heat requirement of vaporization, poor mixing, and other fuels have opposite physicochemical properties, requiring only relatively low ignition energy to have a very high flammability range.
Therefore, at different working condition points of the engine, the mixed multiple fuels with different proportions can not only meet the requirements of power, efficiency and emission, but also can achieve the conditions of suppressing knocking or avoiding fire by quickly adjusting the target air-fuel ratio (the air quality required by the combustion of fuel per unit mass).
Therefore, how to realize accurate and safe control of the engine is an important issue to be solved in the industry.
Disclosure of Invention
The inventor provides a mixed fuel engine injection control method, equipment and medium aiming at the problems and the technical requirements, so as to solve the problems of poor engine operation stability and safety during multi-fuel combustion in the prior art and realize safe and accurate control of the engine.
The embodiment of the application provides a mixed fuel engine injection control method, which comprises the following steps:
calculating corresponding combustion demand torque under the current operation condition of the engine and a target air-fuel ratio corresponding to the mixed fuel;
Calculating a target opening degree of an engine throttle valve corresponding to the combustion demand torque, acquiring actual fresh air flow entering a combustion chamber of the engine under the target opening degree, and obtaining an actual air-fuel ratio based on the actual fresh air flow;
Calculating a first deviation of the target air-fuel ratio from the actual air-fuel ratio;
Inputting a first calculation array corresponding to the current operation condition, a previous second deviation and a mixed fuel injection adjustment coefficient in a previous preset step length into a combustion adjustment transmission model to obtain a current second deviation predicted by the combustion adjustment transmission model, wherein the combustion adjustment transmission model is a preset mathematical model, and the second deviation represents the deviation between the target air-fuel ratio predicted by the combustion adjustment transmission model and the actual air-fuel ratio;
And inputting the first deviation and the second deviation into a control model to obtain a mixed fuel injection adjustment coefficient output by the control model, and obtaining the injection quantity of the mixed fuel based on the mixed fuel injection adjustment coefficient under the condition that the engine control mode is determined to be in a closed-loop control state, wherein the control model is a preset mathematical model.
According to the injection control method of the mixed fuel engine provided by the embodiment of the application, the target air-fuel ratio corresponding to the mixed fuel is calculated, and the method comprises the following steps:
calculating a mixed fuel ratio based on the mass of each fuel in the mixed fuel, and determining an initial air-fuel ratio based on the mixed fuel ratio;
judging whether a correction condition for correcting the initial air-fuel ratio exists or not;
When it is determined that there is a correction condition for correcting the initial air-fuel ratio, a correction coefficient corresponding to the correction condition is acquired, and the initial air-fuel ratio is corrected by using the correction coefficient, thereby obtaining the target air-fuel ratio.
According to the method for controlling injection of a mixed fuel engine provided by the embodiment of the application, judging whether the correction condition for correcting the initial air-fuel ratio exists or not, and when judging that the correction condition for correcting the initial air-fuel ratio exists, acquiring a correction coefficient corresponding to the correction condition comprises the following steps:
judging whether the temperature of cooling water of the engine is less than a preset temperature;
Under the condition that the cooling water temperature is less than a preset temperature, judging that a correction condition for correcting the initial air-fuel ratio exists, and obtaining a first correction coefficient based on the cooling water temperature and a starting time point of an engine;
Judging whether a discharge equipment diagnosis request exists or not under the condition that the cooling water temperature is larger than or equal to the preset temperature;
in the case where it is determined that the emission device diagnosis request exists, it is determined that there is a correction condition in which the initial air-fuel ratio is corrected, and a second correction coefficient is obtained;
judging whether to perform temperature management in the engine tail pipe or not in the case that the emission equipment diagnosis request is judged to be absent;
When it is determined that temperature management in the engine tail pipe is required, determining that there is a correction condition for correcting the initial air-fuel ratio, and obtaining a third correction coefficient;
judging whether the engine has a cylinder breaking phenomenon or not under the condition that the temperature management in the tail pipe of the engine is not required;
when the engine is judged to have a cylinder-off phenomenon, judging that the correction condition for correcting the initial air-fuel ratio exists, and obtaining a fourth correction coefficient;
when it is determined that the engine does not have a cylinder deactivation phenomenon, it is determined that there is no correction for correcting the initial air-fuel ratio.
According to the injection control method of the mixed fuel engine provided by the embodiment of the application, the mixed fuel ratio is calculated, and the method comprises the following steps:
Calculating a replacement ratio of the first fuel which can be replaced by the second fuel;
Acquiring a conversion coefficient converted from the first fuel to the second fuel, and determining the quality of the second fuel corresponding to the replaced first fuel based on the replacement proportion and the conversion coefficient;
and calculating the ratio of the residual mass of the first fuel to the mass of the second fuel to obtain the mixed fuel ratio.
According to the injection control method of the mixed fuel engine provided by the embodiment of the application, the conversion coefficient of converting the first fuel into the second fuel is obtained, and the method comprises the following steps:
Calculating a lower heating value ratio of the first fuel and the second fuel, and determining the lower heating value ratio as an initial conversion coefficient;
Acquiring a first gain coefficient corresponding to the cooling water temperature based on the cooling water temperature of an engine and a preset first coefficient correction table, and acquiring a second gain coefficient corresponding to the change condition of an operating mode of the engine based on the change condition of the operating mode and a preset second coefficient correction table;
And calculating the product of the initial conversion coefficient, the first gain coefficient and the second gain coefficient to obtain the conversion coefficient.
According to the injection control method of the mixed fuel engine provided by the embodiment of the application, the combustion regulation transfer model comprises the following steps:
Y(n) = K0*Y(n-1)+K1*Z(n-d);
wherein Y (n) represents the current second deviation, Y (n-1) represents the last second deviation, and Z (n-d) represents the mixed fuel injection adjustment coefficient pushed forward by d steps at the current moment;
Wherein k0= -1/(1+ts/τ), k1= - (Ts/τ)/(1+ts/τ), d=round (τ_d/Ts);
Wherein, the τ=τ_f+τ _e+τ_s;
where τ_f, τ_e, τ_s, and τ_d represent the first array parameters in the first computation array, and Ts represents the discrete iterative computation frequency, which is a constant.
According to the injection control method of the mixed fuel engine provided by the embodiment of the application, the control model comprises the following steps:
Z(n) = K2* Z(n-1)+K3*D(n)+K4*D(n-1);
Wherein Z (n) represents a mixed fuel injection adjustment coefficient corresponding to the current step length, Z (n-1) represents a mixed fuel injection adjustment coefficient corresponding to the previous step length, D (n) represents a difference value between a first deviation corresponding to the current step length and a second deviation, and D (n-1) represents a difference value between the first deviation corresponding to the previous step length and the second deviation;
Wherein k2=λ/(λ+ts), k3= (- τ -Ts)/(λ+ts), k4=τ/(λ+ts);
Wherein, the τ=τ_f+τ _e+τ_s;
Where τ_f, τ_e, and τ_s represent first array parameters in the first computation array, ts represents the discrete iterative computation frequency, is a constant, and λ represents the first order delay filter time constant.
According to the injection control method of the mixed fuel engine, which is provided by the embodiment of the application, the control model is obtained by carrying out decomposition inversion treatment on the combustion regulation transmission model.
The embodiment of the application also provides electronic equipment, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor executes the program to realize the steps of the injection control method of the mixed fuel engine.
Embodiments of the present application also provide a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method of controlling injection of a mixed fuel engine as defined in any one of the above.
According to the injection control method, equipment and medium for the mixed fuel engine, provided by the embodiment of the application, the accurate mixed fuel injection adjustment coefficient is obtained by calculating the actual deviation between the target air-fuel ratio and the actual air-fuel ratio and the predicted deviation predicted by the combustion adjustment transmission model and utilizing the closed-loop control of the control model in combination with the operation working condition of the engine, so that the accurate calculation of the injection quantity of the mixed fuel is ensured, the accurate output control of the engine fuel is realized, and the safe operation of the engine is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for controlling injection of a mixed fuel engine according to an embodiment of the present application;
FIG. 2 is a second flow chart of an injection control method for a mixed fuel engine according to an embodiment of the present application;
FIG. 3 is a third flow chart of an injection control method for a mixed fuel engine according to an embodiment of the present application;
FIG. 4 is a flow chart of a method for controlling injection of a mixed fuel engine according to an embodiment of the present application;
FIG. 5 is a flow chart of a method for controlling injection of a mixed fuel engine according to an embodiment of the present application;
Fig. 6 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The embodiment of the application provides an injection control method of a mixed fuel engine. The method can be applied to the intelligent terminal, the server and the controller of the vehicle. The present application is described by taking the application of the method to a controller of a vehicle as an example, and some other descriptions of embodiments are not intended to limit the scope of the present application, and will not be described in detail. The specific implementation of the method is shown in fig. 1:
Step 101, calculating corresponding combustion demand torque under the current operation condition of the engine and corresponding target air-fuel ratio of the mixed fuel.
Step 102, calculating a target opening degree of an engine throttle valve corresponding to the combustion demand torque, obtaining an actual fresh air flow rate entering a combustion chamber of the engine at the target opening degree, and obtaining an actual air-fuel ratio based on the actual fresh air flow rate.
Wherein the actual air-fuel ratio is obtained by measurement of a sensor that calculates the actual air-fuel ratio based on the measured oxygen concentration in the exhaust gas at the time of actual fresh air combustion.
Step 103, calculating a first deviation of the target air-fuel ratio from the actual air-fuel ratio.
And 104, inputting the first calculation array corresponding to the current operation condition, the last second deviation and the mixed fuel injection adjustment coefficient in the last preset step length into a combustion adjustment transmission model to obtain the current second deviation predicted by the combustion adjustment transmission model.
The combustion regulation transmission model is a preset mathematical model.
Wherein the second deviation characterizes a deviation of the target air-fuel ratio predicted by the combustion adjustment delivery model from the actual air-fuel ratio.
Step 105, inputting the second calculation array corresponding to the current operation condition, the first deviation and the second deviation into the control model to obtain a mixed fuel injection adjustment coefficient output by the control model, and obtaining the injection quantity of the mixed fuel based on the mixed fuel injection adjustment coefficient under the condition that the engine control mode is determined to be in a closed-loop control state.
The control model is a preset mathematical model.
Specifically, a corresponding relation between the operation condition and the first calculation array and a corresponding relation between the operation condition and the second calculation array are created in advance.
According to the mixed fuel engine injection control method, equipment and medium provided by the embodiment of the application, the accurate mixed fuel injection adjustment coefficient is obtained by calculating the actual deviation between the target air-fuel ratio and the actual air-fuel ratio and the predicted deviation predicted by the combustion adjustment transmission model and utilizing the closed-loop control of the control model in combination with the operation working condition of the engine, so that the accurate calculation of the mixed fuel injection quantity is ensured, the accurate output control of the engine fuel is realized, and the safe operation of the engine is ensured.
In one embodiment, the calculating of the blended fuel ratio comprises:
The method comprises the steps of calculating a replacement proportion of a first fuel capable of being replaced by a second fuel, obtaining a conversion coefficient from the first fuel to the second fuel, determining the mass of the second fuel corresponding to the replaced first fuel based on the replacement proportion and the conversion coefficient, and calculating the ratio of the residual mass of the first fuel to the mass of the second fuel to obtain the mixed fuel ratio.
Specifically, a specific implementation of calculating the replacement ratio of the first fuel that can be replaced with the second fuel is illustrated by fig. 2:
in step 201, a corresponding first fuel demand of the engine in a current operating mode is calculated.
Wherein the first fuel demand is a reference fuel demand.
Specifically, calibration of the working mode and the required quantity of the reference fuel is performed through an engine bench test, and the corresponding relation between the working mode and the required quantity of the reference fuel is obtained.
Under the condition that the engine configuration is fixed, the main influencing factor of the conversion from the combustion demand torque to the fuel is the engine speed, namely calibration is carried out based on the main influencing factor. For example, the correspondence between the combustion demand torque and the engine speed of the engine and the demand amount of the reference fuel is calibrated.
Step 202, calculating a new combustion demand torque and a new first fuel demand for the engine in a future adjacent operating mode.
In particular, this step differs in the mode of operation. The operating modes herein indicate operating modes such as normal engine operating modes or corresponding to different phases of an emission-demanded exhaust, such as a particulate trap (DPF) regeneration mode (raising exhaust temperature, maintaining a re-lift process, etc.), different engine operating mode characteristics including different number of fuel injections in an engine cylinder, whether there is a significant difference in tailpipe injection, injection angle, etc.
In step 203, the mass of the first fuel corresponding to the engine at each moment when the current operation mode is converted into the future adjacent operation mode is calculated.
Specifically, when the operation mode conversion occurs, the mass of the first fuel corresponding to the engine at each moment is calculated in a linear stepwise transition manner to ensure smooth power output, specifically see formula (1):
Q1_SumDmd = Q1_Curr*(1-Frmp)+Q1_Nxt* Frmp............(1)
Where q1_ SumDmd represents the demand for mass of first fuel to be used during the transient (first fuel demand), q1_curr represents the current operating mode first fuel demand, frmp represents the transient change coefficient, and q1_nxt represents the new adjacent operating mode first fuel demand.
Wherein Frmp is gradually transitioned from the transition start initial value of 0 to the transition end value of 1. Each specific calculation process change step size adopts a fixed value or a change value determined by other factors according to implementation requirements.
In step 204, a replacement ratio in the first fuel that can be replaced with the second fuel is calculated.
Wherein the mass of the first fuel used in the actual fuel injection is represented by formula (2):
Q1_dmDmd = Q1_SumDmd*(1- Falt)...........................(2)
Wherein q1_ dmDmd represents the mass of the first fuel used in the actual fuel injection, falt represents the percentage coefficient of the first fuel that can be replaced by the second fuel, i.e. the replacement ratio, wherein Falt is mainly determined by the basic operating conditions determined by the engine speed and the combustion demand torque, considering the influence of different engine cooling water temperatures on the combustion efficiency and the mechanical efficiency, and the emission limit of pollutants and the combustion characteristics of the second mixed fuel.
For example, when diesel fuel and methanol are used as the mixed fuel, diesel fuel is used as the reference fuel 1 (first fuel), and methanol is used as the mixed fuel 2 (second fuel), the use ratio of methanol tends to be increased from an economical point of view, but under the starting and idling conditions of the engine, the fuel mixing is insufficient due to the large vaporization latent heat demand of the methanol fuel, which is liable to cause uneven mixture, poor combustion emission effect, and particularly increase of CO and unburned HC. The use of a higher methanol substitution rate at this time in the low engine load region with less diesel injection results in poor vaporization of some of the methanol and even less combustion out of the engine, and therefore it is not preferred to exceed 20% in these regions Falt. In the medium-large load area, the use ratio of methanol can be properly increased by adjusting the diesel oil injection timing, at the moment, the heating condition in the combustion chamber is improved due to the increase of the diesel oil injection quantity, the difference effect caused by the fuel property is weakened by the mixture gas mixture, at the moment, falt can be increased to about 65%, but as Falt is increased, the probability of knocking of the engine is increased, and further increase of Falt can be limited.
According to the embodiment, the two-dimensional MAP with the engine speed and the combustion required torque as input is formed through the results obtained through the engine bench test, the Falt value under the corresponding working condition is obtained through inquiring the data MAP in real time during control, and the Falt value smooth transition is ensured by considering the transition of the engine under different working modes similar to the transition from the combustion required torque to the required reference fuel.
In one embodiment, a specific implementation of obtaining a conversion coefficient for converting a first fuel to a second fuel is shown in FIG. 3:
in step 301, the lower heating value ratio of the first fuel and the second fuel is calculated and the lower heating value ratio is determined as an initial conversion factor.
For example, the diesel fuel has a low heating value of 42.5MJ/kg, the methanol has a low heating value of 19.7MJ/kg, and the methanol as the alternative fuel has a basic conversion (initial conversion) of 42.5/19.7=2.14, i.e. the combustion of the basic fuel 1 (first fuel) requires 2.14 mass units of the alternative fuel (second fuel).
Step 302, obtaining a first gain coefficient corresponding to the cooling water temperature based on the cooling water temperature of the engine and a preset first coefficient correction table, and obtaining a second gain coefficient corresponding to the change condition of the working mode based on the change condition of the working mode of the engine and a preset second coefficient correction table.
Specifically, calibration is performed in advance, and a first coefficient correction table and a second coefficient correction table are obtained. For example, based on the engine test stand and stable engine cooling water temperatures such as (85-90 ℃) as conversion references, gain coefficients relative to the basic conversion coefficients are acquired when the engine cooling water temperatures are different to form one-dimensional calibration data MAP, and the control is executed to query the MAP in reverse.
And obtaining a second coefficient correction table by the same method. And the fuel conversion coefficient correction when the current operation mode of the engine is changed is considered, and the gradient gentle transition processing is performed during the operation mode transition.
In step 303, the product of the initial conversion coefficient, the first gain coefficient and the second gain coefficient is calculated to obtain the conversion coefficient.
See in particular formula (3):
Fac_Q1to2 = Fac_Q1to2Base*Fac_Q1to2Tcor*F_modeCor.........(3)
where fac_q1to2 represents the conversion coefficient, fac_q1to2Base represents the initial conversion coefficient, fac_q1to2Tcor represents the first gain coefficient, and f_ modeCor represents the second gain coefficient.
In one embodiment, determining the mass of the second fuel corresponding to the replaced first fuel based on the replacement ratio and the conversion factor comprises:
obtaining the mass of the second fuel based on formula (4):
Q2_dmDmd = (Q1_SumDmd - Q1_dmDmd) * Fac_Q1to2.........(4)
Where q2_ dmDmd represents the mass of the second fuel, q1_ SumDmd represents the amount of demand for using the mass of the first fuel, q1_ dmDmd represents the mass of the first fuel used in the actual fuel injection, and fac_q1to2 represents the conversion coefficient.
In one embodiment, calculating the target air-fuel ratio corresponding to the mixed fuel includes:
the method includes the steps of calculating a fuel mixture ratio based on the mass of each fuel in the mixed fuel, determining an initial air-fuel ratio based on the fuel mixture ratio, determining whether a correction condition for correcting the initial air-fuel ratio exists, acquiring a correction coefficient corresponding to the correction condition when the correction condition for correcting the initial air-fuel ratio is determined to exist, correcting the initial air-fuel ratio by the correction coefficient to obtain a target air-fuel ratio, and determining the initial air-fuel ratio as the target air-fuel ratio when the correction condition for correcting the initial air-fuel ratio is determined not to exist.
Wherein the initial air-fuel ratio is the stoichiometric air-fuel ratio.
Specifically, the mass ratio of each fuel in the mixed fuel (mixed fuel ratio) is calculated according to the obtained mass of each fuel in the mixed fuel, such as q1_ dmDmd and q2_ dmDmd in the example, see formula (5) and formula (6):
Fac_Q1 = Q1_dmDmd/( Q1_dmDmd+Q2_dmDmd).........(5)
Fac_Q2 = Q2_dmDmd/( Q1_dmDmd+Q2_dmDmd).........(6)
wherein Fac_Q1 represents a mass ratio corresponding to the first fuel, and Fac_Q2 represents a mass ratio corresponding to the second fuel.
And the initial air-fuel ratio is obtained by the formula (7):
Rnom= R1* Fac_Q1+R2* Fac_Q2...........................(7)
Where Rnom represents an initial air-fuel ratio, R1 represents a stoichiometric air-fuel ratio for fully using the first fuel, and R2 represents a stoichiometric air-fuel ratio for fully using the second fuel.
In one embodiment, the specific implementation of the target air-fuel ratio Robj obtained by correcting or coordinating logic calculating the initial air-fuel ratio Rnom of the mixed fuel through various actual factors is shown in fig. 4:
step 401, determining whether the cooling water temperature of the engine is less than a preset temperature, if yes, executing step 402, otherwise, executing step 403.
Step 402, it is determined that there is a correction for correcting the initial air-fuel ratio, a first correction coefficient is obtained based on the cooling water temperature and the start time point of the engine, and the initial air-fuel ratio is corrected by the first correction coefficient.
Specifically, the cooling water temperature is smaller than the preset temperature indicative of being in the warmed-up state, and the target air-fuel ratio correction calculation in the warmed-up state is performed. Specifically, after the engine is started, a target air-fuel ratio value of a warming process is determined according to two variables of the temperature of cooling water and the starting time, and the target air-fuel ratio value is output after filtering operation is performed. After the warm-up process is finished, switching to default initial air-fuel ratio Rnom.
Step 403, determining whether there is an emission device diagnosis request, if so, executing step 404, otherwise, executing step 405.
Step 404, it is determined that there is a correction condition for correcting the initial air-fuel ratio, a second correction coefficient is obtained, and the initial air-fuel ratio is corrected by using the second correction coefficient.
For example, a diagnostic process for the aftertreatment catalyst is required.
Specifically, it is necessary to adjust the target air-fuel ratio continuously to a sequence of specific values, such as to perform a rich mixture for oxygen removal operation, a lean mixture for oxygen storage operation, and calculate the oxygen storage capacity of the emission treatment device during the continuous change, when it is necessary to perform diagnosis of the emission treatment device, this one target being switched between (Rnom- Δr) and (rnom+Δr) by setting the target air-fuel ratio.
Step 405, it is determined whether or not to perform temperature management in the engine tail pipe, if so, step 406 is executed, and if not, step 407 is executed.
Step 406, it is determined that there is a correction condition for correcting the initial air-fuel ratio, a third correction coefficient is obtained, and the initial air-fuel ratio is corrected by using the third correction coefficient.
Specifically, when the catalyst needs to be heated for exhaust temperature management, the catalyst is heated by making the initial air-fuel ratio smaller and entering the tailpipe with a rich mixture. The target air-fuel ratio at this time is mainly obtained by adjusting the initial air-fuel ratio during heating by the heating request flag, the cooling water temperature, the start time, and the integral adjustment coefficient.
Step 407, judging whether the engine has a cylinder breaking phenomenon, if yes, executing step 408, otherwise, executing step 409.
Step 408, it is determined that there is a correction for correcting the initial air-fuel ratio, a fourth correction coefficient is obtained, and the initial air-fuel ratio is corrected by using the fourth correction coefficient.
Specifically, when there is a catalyst misfire, the initial control air-fuel ratio is adjusted to adjust the fuel injection amount, preventing the injected fuel from entering the tailpipe to burn out the catalyst.
Step 409, it is determined that there is no correction for correcting the initial air-fuel ratio, and the initial air-fuel ratio is determined as the target air-fuel ratio.
In one embodiment, a determination is made as to whether the engine control mode is in an open loop or closed loop state.
Control mode capable of meeting the following conditions entering closed loop control otherwise in open loop mode:
The engine is started and then the warm-up working condition is finished, the actual load of the current engine is higher than a set value, the engine is not in a fuel cut-off state, the delay time after the fuel cut-off is finished meets the requirement, no special open-loop requirement (such as sensor heating not reaching a working state) or test forbidden closed-loop mode caused by the characteristic of an oxygen sensor exists, no hardware faults such as an injector or ignition exist, and no serious fire forced closing fuel injection closed-loop condition exists.
Specifically, the mixed fuel injection adjustment coefficient is obtained based on the processing logic of fig. 1 in the case of the closed-loop state, and is equal to 0 in the case of the open-loop state.
In one embodiment, the first deviation of the calculated target air-fuel ratio from the actual air-fuel ratio is shown in formula (8):
Rdiff = Rreal – Robj.............................................(8)
where Rdiff represents the first deviation, rreal represents the actual air-fuel ratio, and Robj represents the target air-fuel ratio.
Specifically, to avoid disturbance of real-time measurement calculation, the delay characteristic of sensor measurement feedback and the delay characteristic of combustion process are reflected, the control deviation used for control uses an integral algorithm to calculate the correction coefficient fki of Rdiff, and the final control deviation uses Rdiff fki.
In one embodiment, a specific implementation of the creation of the combustion tuning transfer model includes:
The model takes the mixed fuel injection adjustment coefficient and the first calculation array as inputs to predict a second deviation Rmdiff of the actual air-fuel ratio and the target air-fuel ratio within the tailpipe due to the current tuning action.
The following example construction procedure is given, with 4 procedures from fuel injection change to air-fuel ratio deviation change:
a. The fuel path is dynamic, namely, the process from the ECU to the actual fuel injection quantity into the cylinder is calculated.
B. engine cycle dynamics is the inherent delay caused by four strokes of intake, compression, work, and exhaust.
C. exhaust gas delivery dynamics is the physical delivery process of combusted exhaust gas from the cylinder out of the engine, through the exhaust manifold, and to the lambda sensor location.
D. Sensor dynamics Lambda sensor (typically broadband oxygen sensor) response characteristics of its own.
(1) Specific description of the fuel path dynamics:
It is described how the ECU commanded fuel injection pulsewidth translates to actual fuel entering the cylinder. Approximating a first order inertial member.
The Fuel injection amount change (DeltaFuel_CMD) is input.
Output is a change in the amount of Fuel actually entering the cylinder (deltafuel _ Actual).
First transfer function g_fuel(s) =1/(τ_f×s+1).
Where τ_f represents the fuel time constant, characterizes the delays in fuel vaporization, mixing and delivery, and s is a derivative operator of the mathematical representation.
(2) Specific description of the engine cycle delay g_cycle(s):
exhaust gas is produced from the fuel entering the cylinders to the completion of combustion, and it is necessary to go through a complete engine operating cycle. This is a mere time delay.
Delay time (τd_cycle) is the average time from intake valve closing to exhaust valve opening for a four-stroke engine. This delay is directly related to the engine speed (RPM).
Where τ_d_cycle=120/(n×n_cycle) (unit: sec), N: engine speed (RPM), n_cycle: cylinder number.
For example, for a 4 cylinder engine, there are 4 power strokes per cycle (720 crank angle degrees), so the average delay is the interval between two power strokes.
The second transfer function is g_cycle(s) =e (- τ_d_cycle).
Where, - τd_cycle is a standard form in the laplace domain that represents a pure time delay.
(3) Specific description about exhaust gas transport dynamics G_exhaust(s)
It takes time for the exhaust gas to reach the lambda sensor located on the exhaust pipe from the exhaust valve. This includes transmission delays and smoothing effects (low pass filtering) due to gas mixing.
The transfer delay (τd exhaust) depends on the exhaust pipe length and the exhaust gas flow rate (related to engine load and speed).
Smoothing effects can be modeled as a first order inertial link. Thus, this link is a combination of delay + inertia.
The third transfer function is g_exhaust(s) =e (- τ_d_exhaust) 1/(τ_e+1).
Where τ_e represents the exhaust mixing time constant, representing the inertia of the gas mixing in the exhaust pipe.
(4) Specific description of exhaust gas delivery dynamics G_sensor(s)
Lambda sensors are not ideal instantaneous measuring devices per se, have their own response speed, and can generally be approximated by a first-order inertial element.
Fourth transfer function g_sensor(s) =1/(τ_s×s+1).
Where τ_s represents the sensor time constant, where the broadband oxygen sensor responds very fast, τ_s being on the order of tens to one hundred milliseconds.
Specifically, the transfer function of the present application is the product of the above-described first transfer function, second transfer function, third transfer function, and fourth transfer function, see formula (9):
G(s) = (ΔLambda(s)) / (ΔFuel_CMD(s)) = G_fuel(s) * G_cycle(s) * G_exhaust(s) * G_sensor(s)………………………………（9）
Where Δlambda represents the air-Fuel ratio variation amount, Δlambda (s))/(Δfuel_cmd (s)) represents the transmission process from the variation in the Fuel injection amount to the air-Fuel ratio variation amount caused at the engine exhaust gas, corresponding to the four processes described above.
Substituting each link to obtain a formula (10):
G(s) = [1 / (τ_f * s + 1)] * [e^(-τ_d_cycle * s)]* [e^(-τ_d_exhaust * s) / (τ_e * s + 1)] * [1 / (τ_s * s + 1)]…………………………（10）
The delay term can be simplified to yield equation (11):
G(s) = K * [1 / ((τ_f * s + 1)(τ_e * s + 1)(τ_s * s + 1))] * e^(-τ_d * s) ..............................(11)
Where K represents the steady state gain of the system.
In this transfer function, it is typically normalized to 1, since a unit change in fuel trim ultimately results in a unit change in lambda value, but in the opposite direction, an increase in fuel results in a decrease in lambda, and is therefore normalized to-1.
Wherein, the τd=τd_cycle +τ _ d _ exhaust, indicating the total delay. This is the most dominant dynamic in the overall system.
(Tau_f s+1) (tau_e s+1) (tau_s+1) represents an inertial part of the system, and is formed by connecting three first-order inertial links in series, so that the response speed of the system to input is determined.
In order to reduce the complexity of the transfer calculation, the above-mentioned first-order inertia links are combined into an equivalent second-order or first-order link, see formula (12):
G(s) = - e^(-τ_d * s) / (τ * s + 1) ........................(12)
where τ is the equivalent total inertial time constant, τ=τ_f+τ and _e+τ_s.
Discretizing the transfer function (formula 12) described above to calculate a differential that can be realized by a computer is shown in formula (13):
Y(n) = K0*Y(n-1)+K1*Z(n-d)........................(13)
Where Y (n) represents the predicted deviation output Rmdiff in the current calculation step, Y (n-1) represents the predicted deviation output Rmdiff of the last calculation step, Z (n) represents the mixed fuel injection adjustment coefficient in the current calculation step, and Z (n-d) represents the mixed fuel injection adjustment coefficient in the forward pushing d calculation steps.
Where k0= -1/(1+ts/τ), k1= - (Ts/τ)/(1+ts/τ), d=round (τ_d/Ts), and Ts represents the discrete iterative calculation frequency.
In one embodiment, the specific implementation of the mixed fuel injection adjustment coefficient control model creation includes:
The control model is obtained by decomposing and inverting a prediction model (combustion regulation transfer model). The model mismatch and disturbance is robust by comparing the predicted output Rmdiff to the actual output Rdiff to generate the control signal.
First, G(s) = -e (- τ_ds)/(τs+1) is decomposed into a "reversible portion" G_m+(s) and an "irreversible portion" G_m-(s). Namely: gm(s) = [ g_m-(s) (G_m) +(s) ].
The irreversible part includes all pure time delays, corresponding to g_m-(s) =e (- τ_d).
The reversible part comprises a stable and reversible part, g_m+ (S) = -1/(τs+1), the ideal controller is the inverse of g_m+ (S), but the inverse may not be true (higher order than denominator), so a low pass filter F (S) needs to be added to make it possible to achieve and enhance robustness. Then the standard form of the controller is shown in equation (14):
Q(s) = [G_m^+(s)]^{-1} * F(s)...........................(14)
the result after the calculation of the inverse is formula (15):
Q(s) = - (τ* s + 1) / (λ*s + 1) ...........................(15)
wherein F(s) =1/(λ×s+1) represents low-pass filtering.
Wherein τ is consistent with parameters in the prediction model, and represents the total inertia time of the system, and λ represents a first-order delay filtering time constant.
After discretizing the continuous transfer function Q(s), differential operation implemented in a computer, see formula (16):
Z(n) = K2* Z(n-1)+K3*D(n)+K4*D(n-1)...........................(16)
Wherein, D (n) =rmdiff (n) -Rdiff (n), which represents the deviation between the predicted value and the measured value of the tailpipe air-fuel ratio calculated in the current calculation step, D (n-1) is the deviation between the predicted value and the measured value of the tailpipe air-fuel ratio outputted in the previous calculation step, Z (n) is the mixed fuel injection adjustment coefficient in the current calculation step, Z (n-1) is the mixed fuel injection adjustment coefficient in the previous calculation step, k2=λ/(λ+ts), k3= (- τ -Ts)/(λ+ts), k4=τ/(λ+ts), and Ts represents the discrete iteration calculation frequency.
In one embodiment, the determination of the calculation coefficients (K0, K1, K2, K3, K4) in the prediction model and the control model comprises:
Specifically, the fuel evaporation time delay Tfevap, the combustion effect transfer time Ttrans and the sensor dynamic response delay time Tsendly are considered, and these factors are obtained through setting by an engine bench test. The examples were calculated as follows:
The Ttrans combustion effect transfer time may be replaced by a characteristic crank angle time corresponding to each cylinder, for example, the Ttrans is equal to a time corresponding to 180 degrees crank angle for a four-stroke four-cylinder engine, and is calculated according to the formula (17) at different rotation speeds:
Ttrans = 120 /(Eng_spd*w)....................................(17)
Where eng_spd represents the current engine speed, unit rpm, and w represents the number of cylinders.
The MAP data result is obtained through experiments by Tfevap fuel evaporation time, and the input factors of the MAP are obtained by using the engine speed and the basic load and taking the multiplication correction factor of the cooling water temperature to the fuel evaporation into consideration.
The dynamic response time Tsendly of the sensor is directly related to the temperature in the tail pipe and the exhaust flow in the tail pipe, and the two input parameters are used for acquiring result data in the whole working range on the engine bench to form MAP for control.
Wherein τd exhaust, the time of exhaust gas from the exhaust valve to the lambda sensor is measured on the engine bench by two parameters, rotational speed and load.
Thereby obtaining the product, τ=τ_f+τ_e+τu s= Tfevap +ttrans+ Tsendly; τd=τd\u cycle+τ_d/u cycle +) τ_d/u.
Where Ts represents the calculation frequency of the discrete differential equation, a fixed frequency such as 0.01s may be used, where ts=0.01 s, or once per injection event interval, where ts=ttrans=τ_d_cycle.
The first calculation array corresponding to different operation conditions is obtained through the calculation.
For the second calculation array, the filter constant λ used needs to be set. The tuning process starts from an initial value λ=τ, comprehensively considering the robustness and response speed of the system. The following principle is followed:
the smaller the lambda is, the wider the bandwidth of the filter is, the higher frequency control signal can pass through, the system response is faster, but the system oscillation is easy to be unstable.
The larger λ is the narrower the filter bandwidth, the stronger the smoothing (low pass filtering) of the control signal, but the slower the response speed.
The lambda after finishing setting is not necessarily applicable to other working conditions under one engine working condition, so that the engine working condition is set one by taking the engine rotating speed and the load as reference axes, and then the data MAP is recorded for inquiry during subsequent control, and linear interpolation processing is used during transitional working conditions. And after lambda is set, combining with Ts to obtain corresponding second calculation arrays under different operation conditions.
The present application will be specifically described with reference to fig. 5:
In step 501, the combustion demand torque of the engine is calculated.
Specifically, the combustion demand torque is determined according to the usage scenario and the rotational speed of the engine. The combustion torque comprises the output net torque of the crankshaft end of the engine, the engine accessory torque (such as the sum of the driving torques of a water pump, an oil pump and a cooling fan), friction and pumping torque in the working process of the engine, and the like.
Step 502, calculating an engine fuel blend ratio.
Specifically, a mixed fuel engine, because of the use of two or more combustible fuels, can calculate the required mass of each fuel in the mixed fuel based on the torque demand of the engine operating conditions, combustion conditions, pollutant emission limits, operating condition boundaries, and the like.
In step 503, a target air-fuel ratio corresponding to the mixed fuel is calculated.
Specifically, the target air-fuel ratio is corrected to the theoretical air-fuel ratio, and the comprehensive requirements of engine dynamics, emissions and economy are satisfied.
At step 504, a desired fresh air flow corresponding to the combustion demand torque is calculated.
Wherein the air flow is for combustion with the injected fuel mixture in the engine cylinder.
Step 505, determining the target opening degree of the throttle valve of the engine converted from the required fresh air flow, and rapidly and timely controlling the executing mechanism to reach the target opening degree by using a closed-loop control mode.
The air flow through the valve, the temperature of the inlet air, the pressure difference between the front and rear of the valve and the like are considered in calculation during conversion.
Step 506 calculates the actual fresh air flow into the engine combustion chamber based on the actual throttle opening, the pressure sensor and the temperature sensor mounted to the intake manifold.
In step 507, the actual air-fuel ratio of combustion is calculated from the oxygen concentration measured by an oxygen sensor installed in the engine exhaust pipe.
Step 508, a mixed fuel injection adjustment coefficient is calculated based on the target air-fuel ratio and the actual air-fuel ratio.
Step 509 calculates an injection amount of the mixed fuel based on the actual fresh air flow, the mixed fuel injection adjustment coefficient, and the target air-fuel ratio of the engine under the operating condition.
See in particular formula (18):
Mfuel =(Mair/Robj)*(1+Fratio)............(18)
wherein Robj denotes a target air-fuel ratio, mair denotes an actual fresh air flow, mfuel denotes an injection amount, and Fratio denotes a mixed fuel injection adjustment coefficient.
The application relates to a mass ratio calculating method for calculating fuel according to an engine combustion mode and a torque demand, a theoretical air-fuel ratio calculating and correcting method for the combustion of mixed fuel in a cylinder, and a fuel injection quantity closed-loop correction method for meeting a closed-loop control target according to the deviation of an actually measured tail pipe air-fuel ratio and a target set air-fuel ratio by using a model prediction mode, so that the accurate control of the mixed fuel is ensured.
In addition, the application decomposes each link detected by the sensor to build a prediction model for predicting the change value of the air-fuel ratio in the tail pipe corresponding to the fuel adjustment value, wherein the actual air-fuel ratio in the tail pipe from the injection action to the mixed combustion of the cylinder to the tail gas emission to the engine. And then the prediction model is decomposed and inverted to be filtered to obtain a control model, the control model takes prediction deviation Rmdiff and actual measurement deviation Rdiff of the prediction model as inputs to carry out iterative calculation to obtain a fuel injection adjustment coefficient, and the adjustment coefficient is used as the output of the control system to adjust the actual fuel injection quantity, so that the accurate output of the fuel injection quantity is ensured.
Fig. 6 illustrates a physical schematic diagram of an electronic device, which may include a processor 601, a communication interface (Communications Interface) 602, a memory 603, and a communication bus 604, where the processor 601, the communication interface 602, and the memory 603 perform communication with each other through the communication bus 604, as shown in fig. 6. The processor 601 may invoke logic instructions in the memory 603 to execute the hybrid fuel engine injection control method.
Further, the logic instructions in the memory 603 described above may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. The storage medium includes a U disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, an optical disk, or other various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, are capable of performing the method of controlling injection of a mixed fuel engine provided by the methods described above.
In yet another aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform the hybrid fuel engine injection control method provided by the above embodiments.
The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that the above description is only of a preferred embodiment of the application, and the application is not limited to the above examples. It is to be understood that other modifications and variations which may be directly derived or contemplated by those skilled in the art without departing from the spirit and concepts of the present application are deemed to be included within the scope of the present application.
Claims (10)
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| US5623913A (en) * | 1995-02-27 | 1997-04-29 | Honda Giken Kogyo Kabushiki Kaisha | Fuel injection control apparatus |
| US20020043247A1 (en) * | 2000-10-18 | 2002-04-18 | Yoshihiro Majima | Fuel supply amount control apparatus for internal combustion engine |
| JP2007107529A (en) * | 2001-07-25 | 2007-04-26 | Honda Motor Co Ltd | Air-fuel ratio control device for internal combustion engine |
| CN102733970A (en) * | 2011-03-31 | 2012-10-17 | 本田技研工业株式会社 | Air fuel ratio controlling apparatus |
| CN104033257A (en) * | 2014-06-27 | 2014-09-10 | 长城汽车股份有限公司 | Method and system for controlling double-fuel engine |
| JP2016217197A (en) * | 2015-05-15 | 2016-12-22 | トヨタ自動車株式会社 | Engine equipment |
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|---|---|---|---|---|
| US5623913A (en) * | 1995-02-27 | 1997-04-29 | Honda Giken Kogyo Kabushiki Kaisha | Fuel injection control apparatus |
| US20020043247A1 (en) * | 2000-10-18 | 2002-04-18 | Yoshihiro Majima | Fuel supply amount control apparatus for internal combustion engine |
| JP2007107529A (en) * | 2001-07-25 | 2007-04-26 | Honda Motor Co Ltd | Air-fuel ratio control device for internal combustion engine |
| CN102733970A (en) * | 2011-03-31 | 2012-10-17 | 本田技研工业株式会社 | Air fuel ratio controlling apparatus |
| CN104033257A (en) * | 2014-06-27 | 2014-09-10 | 长城汽车股份有限公司 | Method and system for controlling double-fuel engine |
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