Mixing valve opening degree request control method

Abstract

The invention discloses a mixing valve opening degree request control method, which comprises the following steps of: determining a power reduction sub-correction coefficient according to a correction condition of the reduction sub-correction coefficient, and determining an emission sub-correction coefficient according to a correction condition of the emission sub-correction coefficient; when the activation condition is satisfied, determining an updated learning update coefficient; a second multiplication correction coefficient is obtained according to the power reduction sub-correction coefficient, the emission sub-correction coefficient and the updated learning updating coefficient; and the final mixing valve opening change rate is calculated according to the multiplication correction coefficient 2. According to the method, on the basis of the purposes of improving emission and improving the dynamic property, the control precision of an EGR system is balanced, the control precision of an air inlet system is improved, and the change rate of the opening degree of the mixing valve is controlled and optimized by continuously updating the correction coefficient in the process from non-full-opening to full-opening of the mixing valve.

Description

Technical Field

[0001] The invention relates to the field of engine control, and in particular to a mixing valve opening request control method. Background Art

[0002] Exhaust Gas Recirculation (EGR) takes exhaust gas from the exhaust and enters the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock capabilities, and the control of the mixing valve in the low-pressure EGR system is particularly important as a way to improve the EGR rate.

[0003] In the prior art, patent application number CN202011247319.6 "A method and system for calculating a target EGR rate" calculates the initial target EGR rate from the throttle opening, manifold pressure difference and minimum ignition angle, can accurately calculate the target EGR rate, and introduces EGR control activation conditions to perform secondary corrections to the final target EGR rate, but does not consider the control accuracy of the target opening value of the mixing valve; patent application number CN202110184826.8 "A method and system for controlling the target opening of an EGR mixing valve" corrects the target opening of the mixing valve according to various operating parameters, but does not consider the dynamic closed-loop control of the target opening value of the mixing valve.

[0004] In addition, patent CN202110184826.8 "Method for determining target opening of EGR system mixing valve" and patent CN202110184815.X "Method for determining activation state of low-pressure EGR system mixing valve" respectively mentioned transition control in the process of mixing valve from non-fully open (non-activated state) to fully open (activated state), and determined the transition change of target opening of mixing valve. This patent optimizes the change rate of target opening of mixing valve when the mixing valve requests to enter the fully open process, so as to further improve the control stability, power performance and engine safety protection during the control process. Summary of the invention

[0005] The purpose of the present invention is to propose a mixing valve opening request control method based on improving power responsiveness and improving emissions, so as to solve the problems of control stability, power performance and engine safety protection during the process of opening the mixing valve opening.

[0006] The technical solution adopted by the present invention is:

[0007] A method for controlling a mixing valve opening request, the method comprising:

[0008] Determine the power reduction sub-correction factor according to the correction conditions of the reduction sub-correction factor, and determine the emission sub-correction factor according to the correction conditions of the emission sub-correction factor;

[0009] When the activation condition is met, the updated learning update coefficient is determined;

[0010] A multiplication correction factor 2 is obtained according to the power reduction sub-correction factor, the emission sub-correction factor and the updated learning update factor;

[0011] The final mixing valve opening change rate is calculated based on the multiplication correction coefficient two.

[0012] According to the above scheme, the power reduction sub-correction coefficient is determined specifically by the following method:

[0013] When the correction condition of any power reduction sub-correction coefficient is met, the power reduction sub-correction coefficient is obtained by multiplying the characteristic coefficient determined by the throttle full-close time ratio and the intake air volume difference rate by the characteristic coefficient determined by the boost pressure difference rate and the engine speed; the characteristic coefficient determined by the throttle full-close time ratio and the intake air volume difference rate and the characteristic coefficient determined by the boost pressure difference rate and the engine speed are obtained by calibration;

[0014] When all correction conditions of the power reduction sub-correction coefficient are not met, the power reduction sub-correction coefficient is equal to 1.

[0015] According to the above scheme, the emission sub-correction coefficient is determined by the following method:

[0016] When the correction condition of the emission sub-correction coefficient is met, the emission sub-correction coefficient is obtained by multiplying the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate by the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature; the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate and the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature are obtained by calibration;

[0017] When the correction condition of the emission sub-correction coefficient is not met, the emission sub-correction coefficient is equal to 1.

[0018] According to the above scheme, the learning update coefficient after determining the update is obtained specifically in the following way:

[0019] When all activation conditions are met, the updated learning update coefficient is obtained by judging the following situations:

[0020] When the difference between the target engine torque and the actual engine torque exceeds the preset range for a continuous time greater than the preset time, and the difference between the target EGR rate and the actual EGR rate exceeds the preset value, and the absolute value of the difference between the final mixing valve opening change rate and the initial mixing valve opening change rate does not exceed the preset value, the updated learning update coefficient is equal to the last obtained learning update coefficient plus 0.01;

[0021] When the difference between the target engine torque and the actual torque does not exceed a preset range, and the difference between the target EGR rate and the actual EGR rate does not exceed a preset value, and the difference between the target mixing valve opening and the actual mixing valve opening does not exceed a preset value, and the absolute value of the difference between the final mixing valve opening change rate and the initial mixing valve opening change rate exceeds a preset value, the updated learning update coefficient is equal to the last obtained learning update coefficient minus 0.03;

[0022] When neither of the above two situations is satisfied, the updated learning update coefficient is equal to the learning update coefficient obtained last time.

[0023] According to the above scheme, the multiplication correction coefficient 2 is obtained by multiplying the product of the power reduction sub-correction coefficient and the emission sub-correction coefficient by the sum of the updated learning update coefficient and 1.

[0024] According to the above scheme, the final mixing valve opening change rate is obtained by multiplying the initial mixing valve opening change rate by the multiplication correction coefficient of two.

[0025] According to the above scheme, the correction conditions of the power reduction sub-correction coefficient are specifically as follows:

[0026] The throttle fully closed time ratio is not less than the preset value, and the intake volume difference rate is less than a certain preset value;

[0027] The engine speed is less than a preset value, and the boost pressure difference rate is less than a certain preset value.

[0028] According to the above scheme, the correction conditions of the emission correction coefficient are specifically:

[0029] The continuous time that the fluctuation of the amount of gas entering the cylinder exceeds the preset value is greater than the preset time, and the continuous time that the air-fuel ratio difference rate is less than the preset value is greater than the preset time, and the cylinder intake port temperature is greater than the preset temperature, and the target EGR rate does not exceed the preset value.

[0030] According to the above scheme, the activation conditions are specifically:

[0031] The mixing valve is in the transition process from fully open to partially open;

[0032] The supercharger is in the closed-loop control active state;

[0033] The absolute value of the engine target intake pressure change rate exceeds the preset value;

[0034] The absolute value of the engine torque change rate exceeds a preset value;

[0035] The engine mileage corresponding to the failure of the learning update coefficient to be updated exceeds the preset value.

[0036] According to the above scheme, if the fluctuation of the intake air volume difference rate does not exceed the preset value, the characteristic coefficient determined by the throttle full closing time ratio and the intake air volume difference rate remains unchanged;

[0037] If the engine speed fluctuation does not exceed the preset value and the boost pressure difference rate fluctuation does not exceed the preset value, the characteristic coefficient determined by the boost pressure difference rate and the engine speed remains unchanged;

[0038] If the cylinder gas volume fluctuation rate does not exceed the preset value and the air-fuel ratio difference rate does not exceed the preset value, the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate remains unchanged;

[0039] If the cylinder intake port temperature fluctuation does not exceed a preset value and the air-fuel ratio difference rate fluctuation does not exceed a preset value, the characteristic coefficient determined by the cylinder intake port temperature and the air-fuel ratio difference rate remains unchanged.

[0040] According to the above scheme, the fluctuation of the intake volume difference rate is specifically the difference between the intake volume difference rate in this sampling cycle and the intake volume difference rate in the previous sampling cycle;

[0041] The engine speed fluctuation is specifically the difference between the engine speed in this sampling cycle and the engine speed in the previous sampling cycle; the boost pressure difference rate fluctuation is specifically the difference between the boost pressure difference rate in this sampling cycle and the boost pressure difference rate in the previous sampling cycle;

[0042] The fluctuation of the cylinder gas volume fluctuation rate is specifically the difference between the cylinder gas volume fluctuation rate in this sampling cycle and the cylinder gas volume fluctuation rate in the previous sampling cycle; the fluctuation of the air-fuel ratio difference rate is specifically the difference between the air-fuel ratio difference rate in this sampling cycle and the air-fuel ratio difference rate in the previous sampling cycle;

[0043] The cylinder air inlet temperature fluctuation is specifically the difference between the cylinder air inlet temperature in this sampling cycle and the cylinder air inlet temperature in the previous sampling cycle.

[0044] According to the above scheme, the calibration method of the characteristic coefficient determined by the throttle full-close time ratio and the intake volume difference rate is as follows: under the premise that the difference between the target boost pressure and the actual boost pressure at each engine speed is fixed within a certain preset range, by adjusting different throttle full-close time ratios and intake volume difference rates, the continuous time during which the difference between the engine target torque and the actual torque in the transition process from the non-fully open to the fully open mixing valve is controlled within the preset range does not exceed the preset time;

[0045] The calibration method of the characteristic coefficient determined by the boost pressure difference rate and the engine speed is as follows: under the premise that the throttle valve is not fully open and the difference between the target fresh air intake amount entering the cylinder and the actual fresh air intake amount entering the cylinder is within a certain preset range, by adjusting different boost pressure difference rates, the continuous time that the difference between the target boost pressure and the actual boost pressure exceeds the preset range does not exceed the preset time;

[0046] The calibration method of the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate is as follows: under the premise that the cylinder intake port temperature does not exceed the preset value, by adjusting the different cylinder gas volume fluctuation rates and the air-fuel ratio difference rates, the NOx emission in the transition process from the non-fully open to the fully open mixing valve is maintained at a certain preset value;

[0047] The calibration method of the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature is: under the premise that the fluctuation of the amount of gas entering the cylinder does not exceed the preset value and the different air-fuel ratio difference rates are fixed, the NOx emissions in the transition process from the non-fully open to the fully open mixing valve are maintained at a certain preset value by adjusting the cylinder intake port temperature.

[0048] According to the above scheme, the default value of the learning update coefficient is 0, and the learning update coefficient is saved after the vehicle is powered off.

[0049] The beneficial effects of the present invention are as follows: based on the purpose of improving emissions and improving power, the control accuracy of the EGR system is balanced with the improvement of the control accuracy of the intake system, and the control optimization of the mixing valve opening rate is achieved by continuously updating the correction coefficient during the process of the mixing valve changing from non-fully open to fully open. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the architecture of the low-pressure EGR system;

[0051] Figure 2 The present invention is a flow chart of the method.

[0052] In the figure: 1-air filter, 2-mixing valve, 3-supercharger compressor, 4-throttle, 5-engine, 6-supercharger turbine, 7-catalyst, 8-particulate matter trap, 9-EGR cooler, 10-EGR valve, 11-temperature sensor, 12-differential pressure sensor. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] like Figure 1As shown, the low-pressure EGR system includes an air filter, a mixing valve, a supercharger compressor, a throttle, an engine, a supercharger turbine, a catalyst, a particulate matter trap, an EGR cooler, an EGR valve, an EGR temperature sensor, and an EGR differential pressure sensor.

[0055] Among them, the supercharger compressor is used to compress fresh air for supercharging; the supercharger turbine controls the working efficiency of the turbine by controlling the opening of the supercharger's wastegate valve, thereby achieving different supercharging capabilities;

[0056] At the same time, compared with the non-low-pressure EGR system, the low-pressure EGR system has the following additional components: EGR cooler, EGR temperature sensor, EGR valve, EGR pressure difference sensor, and mixing valve. The mixing valve is used to adjust the pressure at the EGR valve outlet, increase the pressure difference at both ends of the EGR valve, and increase the EGR rate; the EGR cooler is used to cool the exhaust gas, which is convenient for increasing the exhaust gas volume and reducing the exhaust gas temperature; the EGR valve has a throttling effect, which is used to control the amount of exhaust gas entering the cylinder; the EGR temperature sensor is used to detect the exhaust gas temperature entering the EGR valve; the EGR pressure difference sensor is used to detect the pressure at the EGR inlet and outlet.

[0057] The present invention provides a mixing valve opening request control method for the above low-pressure EGR system, such as Figure 2 As shown, the method of the present invention mainly comprises the following steps:

[0058] S1. Determine the power reduction sub-correction coefficient according to the correction condition of the reduction sub-correction coefficient, and determine the emission sub-correction coefficient according to the correction condition of the emission sub-correction coefficient.

[0059] Based on the existing technology, the current mixing valve is in a transitional state from non-fully open to fully open, and the current initial mixing valve opening pct is obtained. MGVRaw and initial mixing valve opening change rate dpct MGVRaw .

[0060] S11. Determine the power reduction correction coefficient.

[0061] The correction conditions for the power reduction correction factor are:

[0062] 1. The throttle valve is fully closed (i.e., the throttle valve opening is minimum here to quickly reduce the air volume) time ratio is not less than a preset value (0.05 in this embodiment), and the intake air volume difference rate is less than a certain preset value (-0.05 in this embodiment);

[0063] 2. The engine speed is less than a preset value (1000 rpm in this embodiment), and the boost pressure difference rate is less than a certain preset value (-0.1 in this embodiment).

[0064] When the correction conditions of the power reduction sub-correction coefficient are not met, the power reduction sub-correction coefficient r23 is equal to 1.

[0065] When the correction condition of any power reduction sub-correction coefficient is met, the power reduction sub-correction coefficient r23 is:

[0066]

[0067] in, The throttle valve fully closed time ratio Difference rate with intake volume Determined characteristic coefficient, which is obtained by calibration; among which the throttle full closing time ratio t is the continuous time that the throttle enters the fully closed state ThrMin The maximum time t of throttle valve fully closed ThrMinMax (calibrated as 0.8s in this example), when the throttle valve enters the fully closed state for a continuous time exceeding the maximum time of the throttle valve fully closed, the rate of change of the mixing valve opening remains unchanged, and the intake volume difference rate The target fresh air intake density rho entering the cylinder Dsrd The actual fresh air intake density rho Act The difference rho Dsrd -rho Act The fresh air intake density rho of the target cylinder Dsrd ratio;

[0068] in, is the boost pressure difference rate The characteristic coefficient determined by the engine speed n is also obtained by calibration; among which the boost pressure difference rate is the boost pressure difference p BoostDsrd -p BoostAct and target boost pressure p BoostDsrd The ratio of the boost pressure difference is the target boost pressure p BoostDsrd and the actual boost pressure p BoostAct difference.

[0069] Throttle full closing time ratio When the larger the value is, the longer the time required for the throttle to be fully closed is, indicating that the power torque demand is small, and the characteristic coefficient The smaller it is, the slower the mixing valve is fully opened, to avoid the mixing valve opening being too large, which increases the intake air filling capacity and cannot quickly reduce the air volume; the intake volume difference rate The smaller the value, the greater the overshoot capability of the gas volume response. The smaller it is, the slower the mixing valve will be fully opened, so as to avoid the mixing valve opening being too large, which will increase the air intake capacity and fail to reduce the air volume quickly;

[0070] Boost pressure difference rate The smaller the boost pressure response is, the greater the overshoot is. In order to reduce the overshoot of boost pressure, the characteristic coefficient The smaller the speed, the slower the mixing valve is fully opened, so as to avoid the mixing valve opening being too large and thus increasing the supercharger inlet pressure and failing to improve the supercharger pressure overshoot phenomenon; the larger the speed n, the same boost pressure difference rate The higher the boost response capability at high speed, the higher the characteristic coefficient Also smaller.

[0071] The calibration method is as follows: under the premise that the stable boost pressure response accuracy is good (i.e. the difference between the target boost pressure and the actual boost pressure is within a preset range, and the preset range in this embodiment is ±2 kPa), by adjusting different throttle full closing time ratios and intake volume difference rate Calibration is performed, and the basis for calibration is to ensure that the difference between the target torque and the actual torque of the engine is controlled within a preset range (±5Nm in this embodiment) for a continuous time not exceeding a preset time (0.5s in this embodiment) during the transition process from the mixing valve being partially opened to being fully opened;

[0072] The calibration method is as follows: at each fixed engine speed n, the throttle is not fully open, and the target fresh air intake density rho entering the cylinder Dsrd The actual fresh air intake density rho Act Under the premise that the difference between the target gas volume and the actual gas volume is small (i.e., the difference between the target gas volume and the actual gas volume is within the preset range, and the preset range in this embodiment is ±20 mgpl), the boost pressure difference rate is adjusted to Calibration is performed based on ensuring that the continuous time for which the difference between the target boost pressure and the actual boost pressure exceeds a preset range (±2 kPa in this embodiment) does not exceed a preset time (0.3 s in this embodiment).

[0073] The maximum value is 1 and the minimum value is 0.85. The purpose is to avoid excessive adjustment that causes the difference between the target EGR rate and the actual EGR rate to exceed the preset value (±0.12 in this example);

[0074] The maximum value is 1, and the minimum value is greater than the characteristic coefficient The minimum value of is large, and in this example it is 0.92. The purpose is to give priority to intake volume responsiveness control over boost pressure control. Poor boost pressure responsiveness can be adjusted by the boost actuator, and boost pressure does not directly affect the intake volume entering the cylinder like intake volume, so it will not directly affect the power. And if If the control is too large, it will affect the EGR rate response accuracy, so the setting is made based on this.

[0075] In addition, in order to avoid the difference in intake volume Too frequent fluctuations lead to If the adjustment change is too large and the correction coefficient r23 changes too much, resulting in excessive fluctuations in the mixing valve opening control and poor mixing valve control stability, the following treatment should be performed:

[0076] Intake volume difference rate Fluctuation (difference rate of intake volume during this sampling period) Compared with the last sampling period When the difference between the sampling period and the sampling period in this example is 10ms) does not exceed the preset value (in this example, ±0.1), the characteristic coefficient Remain unchanged.

[0077] In order to avoid the engine speed n and Too frequent fluctuations lead to If the adjustment change is too large and the correction coefficient r23 changes too much, the mixing valve opening control fluctuates too much, resulting in poor mixing valve control stability, thus affecting the response accuracy of the EGR rate, the following treatment is performed:

[0078] The engine speed fluctuation n (the difference between the engine speed in this sampling period and the engine speed in the previous sampling period, the sampling period in this example is 10ms) does not exceed the preset value (in this example, ±40rpm) and Fluctuation (the value of the sampling period) Compared with the last sampling period When the sampling period (in this example, 10ms) does not exceed the preset value (in this example, ±0.12), the characteristic coefficient Remain unchanged.

[0079] S12. Determine the emission correction factor.

[0080] The correction condition of the emission correction coefficient is: the amount of gas entering the cylinder dm Cyl Fluctuation (the amount of gas entering the cylinder during this sampling period, dm Cyl Compared with the gas volume entering the cylinder in the previous sampling cycle dm Cyl The difference between the sampling period and the air-fuel ratio difference rate is 10 ms in this example. The time that the difference exceeds 20 mgpl / 10 ms continuously exceeds the preset value (0.5 s in this example). The time that the continuous value is less than -0.2 exceeds the preset value (0.5s in this example), and the cylinder inlet temperature T Port The target EGR rate is greater than a preset value (50°C in this embodiment), and the target EGR rate does not exceed a preset value (0.1 in this embodiment).

[0081] When the correction condition of the emission sub-correction coefficient is not met, the emission sub-correction coefficient r24 is equal to 1.

[0082] When the correction conditions of the emission sub-correction coefficient are met, the emission sub-correction coefficient r24 is:

[0083]

[0084] in, is the cylinder gas volume fluctuation rate Difference rate of air-fuel ratio The determined characteristic coefficient is obtained by calibration; among which the cylinder gas volume fluctuation rate is the fresh air intake volume dm entering the cylinder during the current sampling period Cyl Compared with the fresh air intake volume dm entering the cylinder in the previous sampling cycle Cyl (z)dm Cyl -dm Cyl (z) and the fresh air intake volume dm entering the cylinder during the current sampling period Cyl ratio, air-fuel ratio difference is the target air-fuel ratio r AFRDsrd The actual air-fuel ratio AFRAct The difference AFRDsrd -r AFRAct and the target air-fuel ratio r AFRDsrd The ratio of

[0085] Air-fuel ratio difference and cylinder inlet temperature T Port The determined characteristic coefficients are also obtained by calibration.

[0086] Cylinder gas volume fluctuation rate The larger the air-fuel ratio difference The smaller it is, the greater the increase in intake air volume and the leaner the air-fuel ratio, the smaller the characteristic coefficient The smaller it is, the slower the mixing valve is fully opened, which prevents the EGR exhaust gas from entering the cylinder with too little gas, which can easily cause an increase in NOx emissions.

[0087] The air-fuel ratio difference The smaller the cylinder inlet temperature T Port The higher the value, the leaner the air-fuel ratio and the higher the intake temperature. The smaller it is, the slower the mixing valve opens, preventing too little EGR exhaust gas from entering the cylinder, which can easily cause an increase in NOx emissions.

[0088] The calibration method is: at the cylinder inlet temperature T PortUnder the premise of not exceeding the preset temperature (55°C in this example), the gas volume fluctuation rate of different cylinders is adjusted. Air-fuel ratio difference Calibration is performed to ensure that the NOx emission remains at a certain preset value during the transition from the mixing valve being partially opened to being fully opened;

[0089] The calibration method is: when the gas volume entering the cylinder is dm Cyl Fluctuation (the amount of gas entering the cylinder during this sampling period, dm Cyl Compared with the gas volume entering the cylinder in the previous sampling cycle dm Cyl The difference between the air-fuel ratio and the sampling period in this example is 10ms) does not exceed a certain preset range (20mgpl / 10ms in this embodiment), and the air-fuel ratio difference rate is fixed. Under this premise, by adjusting the cylinder inlet temperature T Port Calibration is performed based on ensuring that the NOx emissions remain at a certain preset value during the transition from the mixing valve being partially open to being fully open.

[0090] The maximum value is 1, and the minimum value is 0.92, to avoid excessive adjustment that causes the difference between the target EGR rate and the actual EGR rate to exceed the preset value (±0.12 in this example);

[0091] The maximum value is 1 and the minimum value is 0.5, to avoid excessive adjustment that causes the difference between the target EGR rate and the actual EGR rate to exceed the preset value (±0.12 in this example).

[0092] In addition, in order to avoid cylinder gas volume fluctuations and air-fuel ratio difference Too frequent fluctuations lead to If the adjustment change is too large and the correction coefficient r24 changes too much, resulting in excessive fluctuations in the mixing valve opening control and poor mixing valve control stability, the following treatment should be performed:

[0093] Fluctuation rate of gas volume in cylinder Fluctuation (difference rate of intake volume in this sampling period, fluctuation rate of cylinder gas volume The fluctuation rate of the cylinder gas volume compared with the previous sampling period The difference between the sampling period and the air-fuel ratio difference rate is 10ms in this example. Fluctuation (difference rate of air-fuel ratio in this sampling period) The difference between the air-fuel ratio and the last sampling period When the difference (the sampling period in this example is 10ms) does not exceed the preset value (in this example ±0.1), the characteristic coefficient Remain unchanged.

[0094] In order to avoid the cylinder intake temperature T Port and air-fuel ratio difference Too frequent fluctuations lead to If the adjustment change is too large and the correction coefficient r24 changes too much, resulting in excessive fluctuations in the mixing valve opening control and poor mixing valve control stability, the following treatment should be performed:

[0095] At the cylinder inlet temperature T Port Fluctuation (the cylinder inlet temperature T in this sampling period) Port Compared with the cylinder inlet temperature T in the previous sampling cycle Port The difference between the sampling period and the air-fuel ratio difference rate is 10ms in this example. Fluctuation (difference rate of air-fuel ratio in this sampling period) The difference between the air-fuel ratio and the last sampling period When the difference between the sampling period and the sampling period in this example is 10ms) does not exceed the preset value (in this example, ±0.1), the characteristic coefficient Remain unchanged.

[0096] S2. When the activation condition is met, determine the updated learning update coefficient.

[0097] The default value of the learning update coefficient is 0. Its value can be saved after the vehicle is powered off. Adapt2 The purpose of updating is to improve control stability, EGR rate (improve emissions and fuel economy) and EGR rate response accuracy during the control process. The update method can only be activated when the following activation conditions (engine is in a large transient state) are met at the same time:

[0098] 1. The mixing valve is in the transition process from fully open to partially open;

[0099] 2. The supercharger is in the closed-loop control activation state;

[0100] 3. The absolute value of the engine target intake pressure change rate exceeds a preset value, which in this example is 25 kPa / 10 ms;

[0101] 4. The absolute value of the engine requested torque change rate exceeds a preset value, which in this embodiment is 30 Nm / 10 ms;

[0102] 5. The engine mileage corresponding to the learning update coefficient not being updated exceeds a preset value, which in this embodiment is 20,000 kilometers.

[0103] When all activation conditions are met, the updated learning update coefficient r is obtained by judging the following situations Adapt2 :

[0104] Case 1:

[0105] When the difference between the target engine torque and the actual torque exceeds the preset range (±5Nm in this embodiment) for a continuous time greater than the preset time (0.7s in this embodiment), and the difference between the target EGR rate and the actual EGR rate exceeds the preset value (±0.15 in this embodiment), and the absolute value of the difference between the final mixing valve opening rate and the initial mixing valve opening rate is dpct MGVNew -dpct MGVRaw It does not exceed the preset value (-15% / 10ms in this embodiment); at this time, the torque responsiveness is poor, and the EGR rate responsiveness is poor. Based on the priority of torque responsiveness, it is necessary to further improve the torque response accuracy, then:

[0106] r Adapt2 =r Adapt2 (z)+0.01,

[0107] where r A dapt2(z) is the learning update coefficient obtained last time.

[0108] Case 2:

[0109] When the difference between the target engine torque and the actual torque does not exceed the preset range (±5Nm in this embodiment), and the difference between the target EGR rate and the actual EGR rate does not exceed the preset value (±0.1 in this embodiment), and the difference between the target opening of the mixing valve and the actual opening of the mixing valve does not exceed the preset value (±1% in this embodiment), and the absolute value of the difference between the final mixing valve opening change rate and the initial mixing valve opening change rate is |dpct MGVNew -dpct MGVRaw | Exceeds the preset value (-25% / 10ms in this embodiment); at this time, the torque responsiveness is good, and the EGR rate responsiveness is good, then:

[0110] r Adapt2 =r Adapt2 (z)-0.03,

[0111] When the number of times CNT that the above four conditions are met simultaneously exceeds a preset value (10 in this example), an attempt is made to gradually restore the initial mixing valve change rate. CNT is updated only once in each driving cycle. Adapt2 After the update, CNT is cleared and Adapt2 Restart the calculation when an update is needed.

[0112] In other cases, r Adapt =r Adapt (z).

[0113] After the learning update coefficient is updated, the learning update coefficient will no longer be updated in this driving cycle, wherein each time the vehicle is powered on and off is a driving cycle.

[0114] S3. Obtain multiplication correction coefficient 2 according to the power reduction sub-correction coefficient, the emission sub-correction coefficient and the updated learning update coefficient.

[0115] The specific calculation method of the multiplication correction coefficient r2 is:

[0116] r2=r23×r24×(1+r Adapt2 ).

[0117] S4. Calculate the final mixing valve opening change rate according to the multiplication correction coefficient 2.

[0118] Final mixing valve opening change rate dpct MGVNew The specific calculation method is:

[0119] dpct MGVNew =dpct MGVRaw *r2,

[0120] where dpct MGVRaw is the initial mixing valve opening change rate.

[0121] After the final mixing valve opening change rate is obtained, the action behavior of the mixing valve is determined based on the mixing valve target opening and the optimized final mixing valve opening change rate.

[0122] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0123] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0124] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for controlling the opening request of a mixing valve, characterized in that: The method comprises: Determine the power reduction sub-correction factor according to the correction conditions of the reduction sub-correction factor, and determine the emission sub-correction factor according to the correction conditions of the emission sub-correction factor; When the activation condition is met, the updated learning update coefficient is determined; A multiplication correction factor 2 is obtained according to the power reduction sub-correction factor, the emission sub-correction factor and the updated learning update factor; The final mixing valve opening change rate is calculated based on the multiplication correction coefficient two.

2. A method for controlling the opening request of a mixing valve according to claim 1, characterized in that: The power reduction sub-correction coefficient is determined specifically by the following method: When the correction condition of any power reduction sub-correction coefficient is met, the power reduction sub-correction coefficient is obtained by multiplying the characteristic coefficient determined by the throttle full-close time ratio and the intake air volume difference rate by the characteristic coefficient determined by the boost pressure difference rate and the engine speed; the characteristic coefficient determined by the throttle full-close time ratio and the intake air volume difference rate and the characteristic coefficient determined by the boost pressure difference rate and the engine speed are obtained by calibration; When all correction conditions of the power reduction sub-correction coefficient are not met, the power reduction sub-correction coefficient is equal to 1.

3. A method for controlling the opening request of a mixing valve according to claim 1, characterized in that: The emission correction coefficient is determined by the following method: When the correction condition of the emission sub-correction coefficient is met, the emission sub-correction coefficient is obtained by multiplying the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate by the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature; the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate and the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature are obtained by calibration; When the correction condition of the emission sub-correction coefficient is not met, the emission sub-correction coefficient is equal to 1.

4. A method for controlling the opening request of a mixing valve according to claim 1, characterized in that: The determined updated learning update coefficient is obtained specifically in the following manner: When all activation conditions are met, the updated learning update coefficient is obtained by judging the following situations: When the difference between the target engine torque and the actual engine torque exceeds the preset range for a continuous time greater than the preset time, and the difference between the target EGR rate and the actual EGR rate exceeds the preset value, and the absolute value of the difference between the final mixing valve opening change rate and the initial mixing valve opening change rate does not exceed the preset value, the updated learning update coefficient is equal to the last obtained learning update coefficient plus 0.01; When the difference between the target engine torque and the actual torque does not exceed a preset range, and the difference between the target EGR rate and the actual EGR rate does not exceed a preset value, and the difference between the target mixing valve opening and the actual mixing valve opening does not exceed a preset value, and the absolute value of the difference between the final mixing valve opening change rate and the initial mixing valve opening change rate exceeds a preset value, the updated learning update coefficient is equal to the last obtained learning update coefficient minus 0.03; When neither of the above two situations is satisfied, the updated learning update coefficient is equal to the learning update coefficient obtained last time.

5. A method for controlling the opening request of a mixing valve according to claim 1, characterized in that: The multiplication correction coefficient 2 is obtained by multiplying the product of the power reduction sub-correction coefficient and the emission sub-correction coefficient by the sum of the updated learning update coefficient and 1.

6. A method for controlling the opening request of a mixing valve according to claim 1, characterized in that: The final mixing valve opening change rate is obtained by multiplying the initial mixing valve opening change rate by a multiplication correction coefficient of two.

7. A method for controlling the opening request of a mixing valve according to claim 2, characterized in that: The correction conditions of the power reduction sub-correction coefficient are specifically as follows: The throttle fully closed time ratio is not less than the preset value, and the intake volume difference rate is less than a certain preset value; The engine speed is less than a preset value, and the boost pressure difference rate is less than a certain preset value.

8. A method for controlling the opening request of a mixing valve according to claim 3, characterized in that: The correction conditions of the emission correction coefficient are specifically: The continuous time that the fluctuation of the amount of gas entering the cylinder exceeds the preset value is greater than the preset time, and the continuous time that the air-fuel ratio difference rate is less than the preset value is greater than the preset time, and the cylinder intake port temperature is greater than the preset temperature, and the target EGR rate does not exceed the preset value.

9. A method for controlling the opening request of a mixing valve according to claim 4, characterized in that: The activation conditions are specifically: The mixing valve is in the transition process from fully open to partially open; The supercharger is in the closed-loop control active state; The absolute value of the engine target intake pressure change rate exceeds the preset value; The absolute value of the engine torque change rate exceeds a preset value; The engine mileage corresponding to the failure of the learning update coefficient to be updated exceeds the preset value.

10. A method for controlling the opening request of a mixing valve according to claim 2 or claim 3, characterized in that: If the intake air volume difference rate fluctuation does not exceed the preset value, the characteristic coefficient determined by the throttle full-close time ratio and the intake air volume difference rate remains unchanged; If the engine speed fluctuation does not exceed the preset value and the boost pressure difference rate fluctuation does not exceed the preset value, the characteristic coefficient determined by the boost pressure difference rate and the engine speed remains unchanged; If the cylinder gas volume fluctuation rate does not exceed the preset value and the air-fuel ratio difference rate does not exceed the preset value, the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate remains unchanged; If the cylinder intake port temperature fluctuation does not exceed a preset value and the air-fuel ratio difference rate fluctuation does not exceed a preset value, the characteristic coefficient determined by the cylinder intake port temperature and the air-fuel ratio difference rate remains unchanged.

11. A method for controlling the opening request of a mixing valve according to claim 10, characterized in that: The intake volume difference rate fluctuation is specifically the difference between the intake volume difference rate in this sampling cycle and the intake volume difference rate in the previous sampling cycle; The engine speed fluctuation is specifically the difference between the engine speed in this sampling cycle and the engine speed in the previous sampling cycle; the boost pressure difference rate fluctuation is specifically the difference between the boost pressure difference rate in this sampling cycle and the boost pressure difference rate in the previous sampling cycle; The fluctuation of the cylinder gas volume fluctuation rate is specifically the difference between the cylinder gas volume fluctuation rate in this sampling cycle and the cylinder gas volume fluctuation rate in the previous sampling cycle; the fluctuation of the air-fuel ratio difference rate is specifically the difference between the air-fuel ratio difference rate in this sampling cycle and the air-fuel ratio difference rate in the previous sampling cycle; The cylinder air inlet temperature fluctuation is specifically the difference between the cylinder air inlet temperature in this sampling cycle and the cylinder air inlet temperature in the previous sampling cycle.

12. A method for controlling the opening request of a mixing valve according to claim 2 or claim 3 or claim 11, characterized in that: The calibration method of the characteristic coefficient determined by the throttle full-close time ratio and the intake volume difference rate is as follows: under the premise that the difference between the target boost pressure and the actual boost pressure at each engine speed is fixed within a certain preset range, by adjusting different throttle full-close time ratios and intake volume difference rates, the continuous time during which the difference between the engine target torque and the actual torque in the transition process from the non-fully open to the fully open mixing valve is controlled within the preset range does not exceed the preset time; The calibration method of the characteristic coefficient determined by the boost pressure difference rate and the engine speed is as follows: under the premise that the throttle valve is not fully open and the difference between the target fresh air intake amount entering the cylinder and the actual fresh air intake amount entering the cylinder is within a certain preset range, by adjusting different boost pressure difference rates, the continuous time that the difference between the target boost pressure and the actual boost pressure exceeds the preset range does not exceed the preset time; The calibration method of the characteristic coefficient determined by the cylinder gas volume fluctuation rate and the air-fuel ratio difference rate is as follows: under the premise that the cylinder intake port temperature does not exceed the preset value, by adjusting the different cylinder gas volume fluctuation rates and the air-fuel ratio difference rates, the NOx emission in the transition process from the non-fully open to the fully open mixing valve is maintained at a certain preset value; The calibration method of the characteristic coefficient determined by the air-fuel ratio difference rate and the cylinder intake port temperature is: under the premise that the fluctuation of the amount of gas entering the cylinder does not exceed the preset value and the different air-fuel ratio difference rates are fixed, the NOx emissions in the transition process from the non-fully open to the fully open mixing valve are maintained at a certain preset value by adjusting the cylinder intake port temperature.

13. A method for controlling the opening request of a mixing valve according to claim 4, characterized in that: The default value of the learning update coefficient is 0, and the learning update coefficient is saved after the vehicle is powered off.

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