A method for controlling NOx emission of a non-road naturally aspirated diesel engine

Abstract

The application discloses a non-road natural-aspiration diesel engine NOx emission control method and relates to the technical field of diesel engine emission control. The method comprises the following steps: obtaining the NOx emission value in real time through a NOx sensor installed at the exhaust tail pipe part of the natural-aspiration diesel engine; obtaining the NOx set value through the universal NOx emission map of the target rotating speed and the torque set in the ECU control logic; calculating the deviation value of the NOx emission value and the NOx set value, and activating the injection timing correction function when the deviation value is not zero; setting the NOx emission controller, monitoring the deviation of the NOx value and the NOx set value in real time, correcting the NOx emission, and realizing the NOx closed-loop control to prevent the NOx regulation from being over-limited and the engine combustion from being poor. The emission value of the NOx sensor is compared with the preset NOx target value in real time, the injection timing and the torque are adjusted through the ECU control logic, the NOx emission value is kept within the set range, the NOx emission is effectively reduced, and the environmental protection performance of the exhaust emission is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diesel engine emission control, in particular to a NOx emission control method for a non-road naturally aspirated diesel engine. BACKGROUND

[0002] With the increasingly stringent emission regulations, the non-road stage IV limit value requirements for NOx are further reduced. For naturally aspirated diesel engines, due to the absence of EGR and SCR aftertreatment devices for reducing NOx, it is difficult to control the consistency and compliance of NOx emissions under long-time operation and severe working conditions. The NOx emission value of the naturally aspirated diesel engine is likely to exceed the limit value requirements of the stage IV emission regulations.

[0003] The existing naturally aspirated diesel engine does not have EGR and SCR aftertreatment devices for reducing NOx, and the control method for NOx is single. Only the NOx emission value can be controlled in a lower range during the development stage. The NOx emission value under long-time operation and extreme severe working conditions cannot be considered. Real-time monitoring and control of NOx cannot be realized, which makes it difficult to control the consistency and compliance of NOx emissions. SUMMARY

[0004] Based on the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a NOx emission control method for a non-road naturally aspirated diesel engine to solve the above technical problems.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a NOx emission control method for a non-road naturally aspirated diesel engine, comprising:

[0006] The NOx sensor installed in the exhaust tail pipe part of the naturally aspirated diesel engine is used to obtain the NOx emission value in real time;

[0007] The NOx set value is obtained by setting the target speed and torque universal NOx emission map in the ECU control logic;

[0008] The deviation value of the NOx emission value and the NOx set value is calculated. When the deviation value is not zero, the fuel injection timing correction function is activated. When the NOx emission value is greater than the NOx set value, the fuel injection timing or rail pressure is reduced. When the NOx emission value is less than the NOx set value, the fuel injection timing or rail pressure is increased;

[0009] The NOx emission controller is arranged to correct the NOx emission by monitoring the deviation between the NOx value and the NOx set value in real time, so as to realize the closed-loop control of NOx, prevent the over-limit regulation of NOx, and prevent the poor combustion of the engine, wherein the NOx emission controller is provided with a model of NOx positive deviation and negative regulation of the advance angle, a model of NOx negative deviation and positive regulation of the advance angle, a model of NOx positive deviation and negative regulation of the rail pressure, and a model of NOx negative deviation and positive regulation of the rail pressure, so as to directly output the values of the corresponding advance angle and rail pressure in the emission correction.

[0010] The application is further provided that the calculation logic of the NOx set value is:

[0011] wherein NOxCtl_rNOxDesVal is the NOx set value, A is the speed, B is the torque, C is the rail pressure, and D is the advance angle.

[0012] The deviation value between the NOx emission value and the NOx set value is recorded as ΔNO x The calculation logic of the deviation value ΔNOx is: ΔNOx=NOxCtl_rNOxActVal-NOxCtl_rNOxDesVal, wherein NOxCtl_rNOxActVal is the NOx emission value.

[0013] The application is further provided that the ΔNOx signal is filtered by a long filter to output ΔNOxF1t.

[0014] When ΔNOxF1t is within the range of the set maximum value NOxCtrl_rMaxCor and the set minimum value NOxCtrl_rMinCor, the current ΔNOxF1t value is outputted.

[0015] When the ΔNOxF1t value is outputted, an up edge is activated, wherein the signal outputted as 1 in the up edge signal activates the NOx emission correction switch to perform the NOx emission correction.

[0016] The application is further provided that the NOx emission controller is provided with an observer detector, which is used to activate the Observer function to perform the PID correction when the NOx emission value and the NOx set value deviate.

[0017] The application is further provided that, in the NOx emission correction logic, the following is included:

[0018] When ΔNOxF1t is greater than 0, the model of positive deviation of NOx and negative adjustment of advance angle is entered, and a corresponding negative adjustment value of advance angle is outputted based on the value of the current positive deviation of NOx, that is, the value of the positive deviation of NOx and the value of the negative adjustment of advance angle map are set in the control logic of the ECU;

[0019] The sum of the negative adjustment value of advance angle, the base value of advance angle and the PID control value of the ECU emission calibration, and the maximum value of advance angle required are determined, and the smaller one is outputted as the set value of advance angle;

[0020] When ΔNOxF1t is equal to 0, the set value of advance angle is outputted, and if ΔNOxF1t is not equal to 0, the model of positive deviation of NOx and positive adjustment of rail pressure is entered, and a corresponding positive adjustment value of rail pressure is outputted based on the value of the current positive deviation of NOx;

[0021] The sum of the positive adjustment value of rail pressure, the base value of rail pressure and the PID control value of the ECU emission calibration, and the minimum value of rail pressure required are determined, and the larger one is outputted as the set value of rail pressure and the set value of advance angle;

[0022] When ΔNOxF1t is not greater than 0, the model of negative deviation of NOx and positive adjustment of advance angle is entered, and a corresponding positive adjustment value of advance angle is outputted based on the value of the current negative deviation of NOx;

[0023] The sum of the positive adjustment value of advance angle, the base value of advance angle and the PID control value of the ECU emission calibration, and the minimum value of advance angle required are determined, and the larger one is outputted as the set value of advance angle;

[0024] When ΔNOxF1t is equal to 0, the set value of advance angle is outputted, and if ΔNOxF1t is not equal to 0, the model of negative deviation of NOx and positive adjustment of rail pressure is entered, and a corresponding positive adjustment value of rail pressure is outputted based on the value of the current negative deviation of NOx;

[0025] The sum of the positive adjustment value of rail pressure, the base value of rail pressure and the PID control value of the ECU emission calibration, and the minimum value of rail pressure required are determined, and the larger one is outputted as the set value of rail pressure and the set value of advance angle;

[0026] After the set value of rail pressure and the set value of advance angle are outputted, the NOx emission value and the NOx set value are compared, if the NOx emission value is less than the NOx set value, the NOx emission correction is ended, and if the NOx emission value is greater than the NOx set value, the NOx emission correction is continued.

[0027] The application is further configured that, in the PID correction of the activated Observer function, the calculation logic of the PID control value is: Wherein, OutPID is the PID control value, K p , K i and K d are proportional gain, integral gain and differential gain respectively.

[0028] The application is further configured to further comprise: calculation logic of the negative adjustment value of the advance angle: Wherein, ΔΦ neg is the negative adjustment value of the advance angle, K1 and K2 are negative adjustment coefficients of the advance angle, and λ1 and μ1 are negative control coefficients of the advance angle.

[0029] The application is further configured to further comprise: calculation logic of the negative adjustment value of the rail pressure: Wherein, ΔP neg is the negative adjustment value of the rail pressure, N1 and N2 are negative adjustment coefficients of the rail pressure, and λ2 and μ2 are negative control coefficients of the rail pressure.

[0030] The application is further configured to further comprise: calculation logic of the positive adjustment value of the advance angle: Wherein, ΔΦ pos is the positive adjustment value of the advance angle, M1 and M2 are positive adjustment coefficients of the advance angle, and λ3 and μ3 are positive control coefficients of the advance angle.

[0031] The application is further configured to further comprise: calculation logic of the positive adjustment value of the rail pressure: Wherein, ΔP pos is the positive adjustment value of the rail pressure, Q1 and Q2 are positive adjustment coefficients of the rail pressure, and λ4 and μ4 are positive control coefficients of the rail pressure.

[0032] The application provides a non-road natural aspirated diesel engine NOx emission control method, which acquires the NOx emission value in real time through a NOx sensor installed in the exhaust tail pipe part of the natural aspirated diesel engine, acquires the NOx set value through the universal NOx emission map of the target rotating speed and torque in the ECU control logic, calculates the deviation value of the NOx emission value and the NOx set value, activates the injection timing correction function when the deviation value is not zero, wherein when the NOx emission value is greater than the NOx set value, the injection timing or rail pressure is reduced, and when the NOx emission value is less than the NOx set value, the injection timing or rail pressure is increased, and the NOx emission controller is set to correct the NOx emission by monitoring the deviation of the NOx value and the NOx set value in real time, so as to realize the NOx closed-loop control and prevent the NOx regulation from being too limited and the engine combustion from being poor, wherein the NOx emission controller is provided with the model of the NOx positive deviation and the negative adjustment of the advance angle, the model of the NOx negative deviation and the positive adjustment of the advance angle, the model of the NOx positive deviation and the negative adjustment of the rail pressure, and the model of the NOx negative deviation and the positive adjustment of the rail pressure, which are used to directly output the corresponding advance angle and rail pressure value in the emission correction, and the beneficial effects include:

[0033] 1. Accurate control of NOx emission: The application compares the emission value of the NOx sensor with the preset NOx target value in real time, and adjusts the injection timing and torque through the ECU control logic, so that the NOx emission value is kept within the set range, effectively reducing the NOx emission and improving the environmental protection performance of the exhaust emission.

[0034] 2. Dynamic adaptation to different working conditions: The application designs multiple control models, including positive and negative deviation control models, and PID control mode based on observer correction, which can dynamically adjust the NOx emission under different working conditions, improve the response speed and adaptability of the system, and ensure stable NOx emission control in complex working environment.

[0035] 3. Avoid engine abnormal condition: Through monitoring and adjusting the NOx emission value, the engine tuning out of control and power output abnormality caused by excessive NOx emission are prevented, the running stability and safety of the engine are effectively improved, and the risk of engine damage caused by non-compliance emission is reduced.

[0036] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, and to implement the content of the specification, and in order to make the above and other purposes, features and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without any creative effort. In the drawings:

[0038] Figure 1 A flow chart of a non-road naturally aspirated diesel engine NOx emission control method is shown for an exemplary embodiment of the present application;

[0039] Figure 2 A flow chart of an emission controller of a non-road naturally aspirated diesel engine NOx emission control method is shown for an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0040] The embodiments of the present application will be described hereinafter with reference to the drawings and preferred embodiments, and other advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in the present specification. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details of the present specification based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, and are not intended to limit the protection scope of the present application.

[0041] It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The shape, number and ratio of the components when actually implemented can be arbitrarily changed, and the layout pattern of the components can also be more complex.

[0042] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application, however, it is obvious for those skilled in the art that the embodiments of the present application can be implemented without these specific details, and in other embodiments, the known structures and devices are shown in the form of block diagrams instead of details, to avoid making the embodiments of the present application difficult to understand.

[0043] A non-road naturally aspirated diesel engine NOx emission control method, as shown in Figure 1 includes:

[0044] The NOx emission value is obtained in real time by the NOx sensor installed at the exhaust tail pipe part of the naturally aspirated diesel engine;

[0045] The NOx setting value is obtained through a universal NOx emission map of target rotating speed and torque set in the ECU control logic;

[0046] The deviation value of the NOx emission value and the NOx setting value is calculated, and when the deviation value is not zero, the fuel injection timing correction function is activated, wherein when the NOx emission value is greater than the NOx setting value, the fuel injection timing or rail pressure is reduced, and when the NOx emission value is less than the NOx setting value, the fuel injection timing or rail pressure is increased;

[0047] The NOx emission controller is set to correct the NOx emission by monitoring the deviation of the NOx value and the NOx setting value in real time, for realizing the NOx closed-loop control and preventing the NOx regulation from being too limited, and the engine combustion from being poor, wherein the NOx emission controller is provided with a model of NOx positive deviation and negative adjustment of the advance angle, a model of NOx negative deviation and positive adjustment of the advance angle, a model of NOx positive deviation and negative adjustment of the rail pressure, and a model of NOx negative deviation and positive adjustment of the rail pressure, for directly outputting the corresponding advance angle and rail pressure value in the emission correction.

[0048] Specifically, the NOx sensor is installed at a certain distance from the exhaust tail pipe of the naturally aspirated diesel engine, and the specific value of the distance is not limited, for obtaining the NOx emission value in real time, and the NOx setting value is obtained through the universal NOx emission map of target rotating speed and torque set in the ECU control logic; in a feasible embodiment of the application, the universal NOx emission map of rotating speed and torque is shown in the following table:

[0049] RPM Torque Bs_Nox NOx InjCrv_phiMI1Des Rail_pSetPoint 1600 878.1 3.26 480.3 10 1000000 1600 811.2 1.9 244.2 0 1000000 1600 765.1 3.61 479.1 0 1600000 1600 809.3 6.21 912 10 1600000 1600 382.5 2.62 275.5 2 1053600 1900 382.5 2.42 229.2 3 1423000 1900 382.6 2.8 275.4 5 1600000 1900 382.5 2.39 233 5 1300000 1900 382.6 1.9 178.7 0 1300000 1900 382.6 3.23 324.2 10 1300000 1900 382.4 1.96 188.3 5 1000000 1900 625 1.94 236.6 5 1300000 2200 507.8 1.84 177.2 0 1600000 2200 570.3 3.07 342.9 10 1600000 2200 473.9 1.43 125.2 0 1000000 2200 560.8 2.01 215.1 10 1000000 2200 383.1 2.1 189.8 5 1300000 1400 150 4.89 263.6 2 995000 1000 150 12.34 544.7 5 701400 1200 100 7.32 239.4 2 803600 750 -1.8 -197.48 112.8 1 464400 2200 563.1 3.04 330.2 8 1600000

[0050] As shown in the above table, the rotating speed represents the rotating speed of the naturally aspirated diesel engine, the torque represents the torque output by the engine, Bs_Nox represents the NOx emission amount under unit brake power, NOx is the NOx setting value under the above condition, lnjCrv_phiMI1Des is the expected fuel injection timing, i.e. the advance angle, representing the fuel injection curve, and Rail_pSetPoint represents the set value of the fuel rail pressure.

[0051] As shown in the above table, the rotating speed represents the rotating speed of the naturally aspirated diesel engine, the torque represents the torque output by the engine, Bs_Nox represents the NOx emission amount under unit brake power, NOx is the NOx setting value under the above condition, lnjCrv_phiMI1Des is the expected fuel injection timing, i.e. the advance angle, representing the fuel injection curve, and Rail_pSetPoint represents the set value of the fuel rail pressure. Figure 2

[0052] The NOx emission value (NOxCtl_rNOxActVal) measured by the NOx sensor in real time is compared with the NOx setting value (NOxCtl_rNOxDesVal) of the universal NOx emission map of target rotating speed and torque set in the ECU, to obtain the ΔNOx signal, and the deviation value of the NOx emission value and the NOx setting value is recorded as ΔNOx. x ​, the calculation logic of the deviation value ΔNOx is: ΔNOx=NOxCtl_rNOxActVal-NOxCtl_rNOxDesVal, wherein NOxCtl_rNOxActVal is the NOx emission value, and the calculation logic of the NOx setting value is:

[0053] Wherein, NOxCtl_rNOxDesVal is the NOx setting value, A is the speed, B is the torque, C is the rail pressure, and D is the advance angle.

[0054] The application further provides that the ΔNOx signal is filtered by a long filter (DT1) to output ΔNOxF1t.

[0055] When ΔNOxF1t is within the range of the set maximum value NOxCtrl_rMaxCor and the set minimum value NOxCtrl_rMinCor, the current ΔNOxF1t value is outputted.

[0056] When the ΔNOxF1t value is outputted, a rising edge is activated, wherein the signal outputted as 1 in the rising edge signal activates the NOx emission correction switch (NOxCtl_SwtCor) to perform NOx emission correction.

[0057] The application further provides that an observer detector is arranged in the NOx emission controller, and the observer detector is used to activate the Observer function to perform PID correction when the NOx emission value and the NOx setting value deviate.

[0058] The application further provides that in the NOx emission correction logic, the following is included:

[0059] ΔNOxF1t is determined, when ΔNOxF1t is greater than 0, the Model Of NOxCtl_DvtPos To PhiMI_CorNeg of the positive deviation of NOx and the negative adjustment of the advance angle is entered, the negative adjustment value (PhiMI_PhiCorNeg) of the advance angle corresponding to the value of the current positive deviation of NOx is outputted, that is, the NOx positive deviation value and the negative adjustment value map of the advance angle are set in the control logic of the ECU.

[0060] The negative adjustment value of the advance angle is added to the sum of the advance angle base value (PhiMI_Bas) and PID control values (PhiMI_PhiOutP, PhiMI_PhiOutI, PhiMI_PhiOutD) of the ECU emission calibration, and the advance angle required maximum value (PhiMI_PhiLimMax) is determined, and the smaller one is output as the advance angle setting value (PhiMI_PhiDes);

[0061] The ΔNOxF1t is determined according to the advance angle setting value, and when ΔNOxF1t is equal to 0, the advance angle setting value (PhiMI_PhiDes) is output, and if ΔNOxF1t is not equal to 0, the model of NOx positive deviation and negative adjustment of rail pressure (Model OfNOxCtl_DvtPos To RailP_CorNeg) is entered, and the corresponding negative adjustment value of rail pressure (Rail_PhiCorNeg) is output based on the value of the current NOx positive deviation;

[0062] The negative adjustment value of the rail pressure is added to the sum of the rail pressure base value (RailP_Bas) and PID control values (RailP_POutP, RailP_POutI, RailP_POutD) of the ECU emission calibration, and the rail pressure required maximum value (RailP_MinLimMax) is determined, and the smaller one is output as the rail pressure setting value (PhiMI_PhiDes) and the advance angle setting value (PhiMI_PhiDes);

[0063] The ΔNOxF1t is determined according to the rail pressure setting value (PhiMI_PhiDes) and the advance angle setting value (PhiMI_PhiDes), and when ΔNOxF1t is not greater than 0, the model of NOx negative deviation and positive adjustment of advance angle (Model OfNOxCtl_DvtNeg To PhiMI_CorPos) is entered, and the corresponding positive adjustment value of advance angle (Rail_PhiCorPos) is output based on the value of the current NOx negative deviation;

[0064] The positive adjustment value of the advance angle (Rail_PhiCorPos) is added to the sum of the advance angle base value (RailP_Bas) and PID control values (RailP_POutP, RailP_POutI, RailP_POutD) of the ECU emission calibration, and the advance angle required minimum value (RailP_MinLimMin) is determined, and the larger one is output as the advance angle setting value (PhiMI_PhiDes);

[0065] According to the advance angle setting value, ΔNOxF1t is determined. When ΔNOxF1t is equal to 0, the advance angle setting value (PhiMI_PhiDes) is outputted, and if not equal to 0, the model of NOx Ctl_DvtNeg To RailP_CorPos is entered, and the corresponding positive adjustment value of rail pressure (Rail_PhiCorPos) is outputted based on the current value of NOx negative deviation;

[0066] The positive adjustment value of rail pressure is added to the sum of the rail pressure basic value (RailP_Bas) of ECU emission calibration and the PID control value (RailP_POutP RailP_POutI RailP_POutD), and is compared with the rail pressure required minimum value (RailP_MinLimMin). The larger one is outputted as the rail pressure setting value (PhiMI_PhiDes) and the advance angle setting value (PhiMI_PhiDes).

[0067] After the rail pressure setting value and the advance angle setting value are outputted, the NOx emission value and the NOx setting value are compared. If the NOx emission value is less than the NOx setting value, the NOx emission correction is ended, and if the NOx emission value is greater than the NOx setting value, the NOx emission correction is continued.

[0068] In a feasible embodiment of the present application, in the PID correction process with the Observer function activated, the calculation logic of the PID control value is as follows: In the formula, OutPID is the PID control value, K p , K i and K d are the proportional gain, the integral gain and the differential gain respectively. Specifically, the formula combines the current deviation, the historical accumulation of the deviation and the change trend of the deviation to calculate the control output OutPID, so as to adjust the injection timing and the rail pressure of the diesel engine, and to realize the accurate control of NOx emission. The proportional control term is directly proportional to the current deviation value, and is used to quickly adjust the output by the size of the current deviation, so as to quickly respond to the deviation and reduce the amplitude of the deviation. The integral control accumulates the total of the deviation over time, and is used to correct the system deviation in the long term, so as to realize zero steady-state error by accumulating the historical error. The differential control term predicts the change trend of the error, and is used to prevent the system from responding too quickly or generating oscillation, and to smooth the dynamic response of the system. The proportional gain K p determines the response strength of the controller to the current deviation, and depends on the dynamic characteristics of the system. The value range of K p is 0.1 to 10. Increasing K i will accelerate the response speed, but may cause system oscillation. The integral gain K i determines the influence of the accumulated error on the control output, and the value range of K i is 0.01 to 1. A larger K i will increase the response speed, but may cause system oscillation.i Can eliminate steady-state error, but may cause system overshoot or oscillation; differential gain K d Determine the error rate of influence on the control output, the value range is 0.001 to 1, greater K d Can reduce overshoot, but may make the system more sensitive to noise; through the proportional term to realize the fast response to the current deviation, ensure that the emission control can respond to mutations in time; the integral term accumulates the deviation, ensures that the system eventually reaches the set value, solves the steady-state error problem that may exist in simple proportional control; the introduction of the differential term reduces the overshoot and oscillation of the system, ensures more stable in the response process.

[0069] The application is further provided to further comprise: calculation logic of negative adjustment value of advance angle: Wherein, ΔΦ neg The negative adjustment value of advance angle, K1 and K2 are the negative adjustment coefficients of advance angle, λ1 and μ1 are the negative control coefficients of advance angle. Specifically, when the NOx emission value is higher than the target value, the generation of NOx needs to be suppressed by adjusting the advance angle. The negative adjustment of the advance angle means reducing the injection advance angle, so that the combustion phase is pushed back, thereby reducing the combustion temperature and reducing the generation of NOx; K1 controls the direct proportional term, the value range is 0.01 to 5, the larger value responds quickly to the deviation, suitable for the situation that requires to reduce NOx, K2 reflects the quadratic influence of the deviation, the value range is 0.001 to 2, increasing will significantly suppress larger deviation and prevent NOx from exceeding the standard; λ1 adjusts the smoothness of the exponential control, the value range is 0.1 to 10, the greater the smoother the effect is. μ1 is the sensitivity adjustment coefficient, the value range is 0.01 to 1, the higher represents the stronger sensitivity to the change of the deviation; the above calculation logic combines the proportional term and the nonlinear term, adjusts the proportional coefficient and the square term of the deviation to realize the sensitive response to the positive deviation of NOx, and introduces the exponential control term to smooth and limit the adjustment amount, prevent over-adjustment.

[0070] The application is further provided to further comprise: calculation logic of negative adjustment value of rail pressure: Wherein, ΔP negis the negative adjustment value of rail pressure, N1 and N2 are the negative adjustment coefficients of rail pressure, and λ2 and μ2 are the negative control coefficients of rail pressure. Specifically, when the NOx emission value is higher than the target value, the combustion temperature needs to be reduced by adjusting the rail pressure. The negative adjustment of the rail pressure means reducing the fuel injection pressure, resulting in an increase in the fuel atomization particle size, thereby delaying the combustion speed, reducing the combustion temperature, and reducing the generation of NOx; N1 determines the direct response of the rail pressure to the deviation, and the value range is 0.01 to 3, the larger the value, the faster the response of the rail pressure, which is suitable for dealing with rapid changes in NOx emissions; N2 controls the nonlinear response to the square root of the deviation, and the value range is 0.001 to 1, which is used to suppress the generation of NOx when the deviation is large, λ2 is used to control the smoothness of the adjustment value, and the range is usually 0.1 to 5, which ensures that there is no large fluctuation in the adjustment process; the sensitivity coefficient μ2 has a value range of 0.01 to 0.5, which affects the degree of rapid response to the change of the deviation, the larger the value, the more sensitive the system to the change of the deviation, the above calculation logic combines the linear response and square root response of the deviation, limits and smooths the adjustment value through the introduced exponential term, prevents the rail pressure from being adjusted too much, and maintains the stability of the system.

[0071] The application further provides that the calculation logic of the positive adjustment value of the advance angle further comprises: Wherein, ΔΦ pos is the positive adjustment value of the advance angle, M1 and M2 are the positive adjustment coefficients of the advance angle, and λ3 and μ3 are the positive control coefficients of the advance angle. Specifically, when the NOx emission value is lower than the target value, the combustion efficiency needs to be improved by increasing the advance angle. The positive adjustment of the advance angle means increasing the fuel injection advance angle, so that the combustion starts earlier, improves the combustion efficiency, and helps to maintain the power output of the engine. M1 controls the linear response to the deviation, and the value range is 0.01 to 2, a larger value is used to quickly adjust the advance angle when the NOx emission is low; M2 reflects the 1.5th nonlinear response of the deviation, and the value range is 0.001 to 1, which is suitable for making more significant adjustments to large deviations to avoid too low combustion efficiency; the smooth adjustment term λ3 has a value range of 0.1 to 10, which ensures smooth response under different deviations; the sensitivity coefficient μ3 has a value range of 0.01 to 0.5, the higher the value, the faster the response to the deviation, which ensures the rapid adjustment of the system to the combustion state; the above calculation logic combines the linear response and 1.5th response of the deviation, and the adjustment value is controlled smoothly through the exponential term to avoid excessive adjustment and cause unstable combustion.

[0072] The application further provides that the calculation logic of the positive adjustment value of the rail pressure further comprises: Wherein, ΔP posis a positive rail pressure adjustment value, Q1 and Q2 are positive rail pressure adjustment values, λ4 and μ4 are positive rail pressure control coefficients; specifically, when the NOx emission value is lower than the target value, increasing the rail pressure can increase the fuel injection pressure and atomization effect, making the combustion more sufficient. The positive adjustment of the rail pressure aims to improve the combustion process and avoid the situation that the power is insufficient due to excessive reduction of NOx. Q1 is a linear adjustment coefficient, the value range is 0.01 to 3, which is suitable for direct and rapid response to NOx deviation and rapid improvement of combustion efficiency; the quadratic adjustment coefficient Q2, the value range is 0.001 to 1, is used for fine adjustment of larger deviation and enhances the adjustment effect; the smoothing coefficient λ4 of the control rail pressure adjustment, the value range is 0.1 to 10, ensures the stability of the adjustment amount change and avoids excessive rail pressure fluctuation; the sensitivity coefficient μ4, the value range is 0.01 to 0.5, adjusts the sensitivity of the exponential term, so that the adjustment process has good response to deviation change; the above calculation logic combines linear and nonlinear adjustment of quadratic, refines the deviation, and introduces the exponential term to smooth and limit the adjustment value, ensuring the stability of the adjustment process.

[0073] The above embodiments can be realized wholly or partially by software, hardware, firmware or any other combination. When realized by software, the above embodiments can be realized wholly or partially in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are wholly or partially generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center and the like containing one or more available medium collections. The available medium can be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape), an optical medium (such as a DVD) or a semiconductor medium. The semiconductor medium can be a solid state disk.

[0074] It should be understood that the term "and / or" in this document is merely used to describe associated relationship, and it can mean three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. In addition, the character " / " in this document generally means that the associated objects before and after the " / " are in an "or" relationship, but can also mean an "and / or" relationship, which can be understood according to the context before and after.

[0075] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of the items, including single item or any combination of multiple items. For example, at least one of a, b, or c can mean a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be singular or plural.

[0076] It should be understood that the order of the above processes in various embodiments of the present application does not mean the order of execution, and the execution order of the processes should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0077] Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0078] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0079] In several embodiments provided in the present application, it should be understood that the disclosed system can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed objects can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0080] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0081] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit.

[0082] If the functions are realized in the form of software functional units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the part of the present application that essentially contributes to the prior art or the part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program code storage media.

[0083] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for controlling NOx emissions from a non-road naturally aspirated diesel engine, characterized in that, include: NOx emission values ​​are acquired in real time by a NOx sensor installed at the exhaust tailpipe of a naturally aspirated diesel engine. The NOx setpoint is obtained by setting the universal NOx emission map for the target speed and torque in the ECU control logic; Calculate the deviation between the NOx emission value and the NOx set value. When the deviation is not zero, activate the injection timing correction function. Specifically, when the NOx emission value is greater than the NOx set value, reduce the injection timing or rail pressure. When the NOx emission value is less than the NOx set value, increase the injection timing or rail pressure. A NOx emission controller is set up to perform NOx emission correction by monitoring the deviation between the NOx value and the NOx set value in real time. This is used to achieve NOx closed-loop control and prevent NOx over-limit and poor engine combustion. The NOx emission controller is equipped with models for adjusting NOx positive deviation and advance angle negatively, NOx negative deviation and advance angle positively, NOx positive deviation and rail pressure negatively, and NOx negative deviation and rail pressure positively. These models are used to directly output the corresponding advance angle and rail pressure values ​​during emission correction. The calculation logic for the NOx setpoint is as follows: in, Set a value for NOx. For rotational speed, For torque, For rail pressure, It is the advance angle; The deviation between the NOx emission value and the NOx setpoint is denoted as... Deviation value The calculation logic is as follows: ,in, This represents NOx emissions.

2. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 1, characterized in that, The signal is filtered and output after passing through a long filter. ; when Within the range of setting the maximum value NOxCtrl_rMaxCor and the minimum value NOxCtrl_rMinCor, output the current value. value; when After the value is output, a rising edge is activated. The signal with a value of 1 in the rising edge signal activates the NOx emission correction switch to perform NOx emission correction.

3. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 2, characterized in that, The NOx emission controller is equipped with an observer detector. The observer detector is used to activate the Observer function and perform PID correction when there is a deviation between the NOx emission value and the NOx set value.

4. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 3, characterized in that, The NOx emission correction logic includes: conduct Determine, when When the value is greater than 0, the model of negative adjustment of NOx positive deviation and advance angle is entered. Based on the current value of NOx positive deviation, the corresponding negative adjustment value of advance angle is output. That is, the control logic in the ECU sets the value of NOx positive deviation and the negative adjustment value of advance angle map. The negative adjustment value of the advance angle is added to the sum of the advance angle base value and the PID control value calibrated by the ECU emission standard, and the advance angle needs to be determined by the maximum value. The smaller of the two is taken, and the advance angle set value is output. Perform according to the advance angle setting value Determine, when When it equals 0, output the advance angle setting value; if If the value is not equal to 0, the model for negative adjustment of NOx positive deviation and rail pressure is entered, and the corresponding negative adjustment value of rail pressure is output based on the current value of NOx positive deviation. The negative adjustment value of the rail pressure is added to the baseline value of the rail pressure calibrated by the ECU emission and the sum of the values ​​obtained through PID control, and the maximum value of the rail pressure required is used for judgment. The smaller of the two is taken, and the rail pressure set value and advance angle set value are output. Perform according to the rail pressure setting value and advance angle setting value. Determine, when When the value is not greater than 0, the model of positive adjustment of NOx negative deviation and advance angle is entered, and the corresponding positive adjustment value of advance angle is output based on the current value of NOx negative deviation; The positive adjustment value of the advance angle is added to the base value of the advance angle calibrated by the ECU emission and the sum of the PID control value. The minimum value of the advance angle is then used to determine the advance angle. The larger of the two values ​​is taken, and the advance angle set value is output. Perform according to the advance angle setting value Determine, when Δ If Flt equals 0, the advance angle setting value is output. If it is not equal to 0, the model of positive adjustment of NOx negative deviation and rail pressure is entered, and the corresponding positive adjustment value of rail pressure is output based on the current value of NOx negative deviation. The positive adjustment value of the rail pressure is added to the baseline value of the rail pressure calibrated by the ECU emission and the sum of the values ​​obtained through PID control. The minimum value of the rail pressure is then used to determine the result. The larger of the two values ​​is taken, and the rail pressure setpoint and advance angle setpoint are output. After outputting the rail pressure setting value and advance angle setting value, the NOx emission value is obtained and compared with the NOx setting value. If the NOx emission value is less than the NOx setting value, the NOx emission correction ends. If the NOx emission value is greater than the NOx setting value, the NOx emission correction continues.

5. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 3, characterized in that, When activating the Observer function and performing PID correction, the calculation logic for the PID control value is as follows: ,in, For PID control values, , and These are proportional gain, integral gain, and derivative gain, respectively.

6. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 4, characterized in that, It also includes: the calculation logic for the negative adjustment value of the advance angle: ,in, This is the negative adjustment value for the advance angle. and This is the negative adjustment coefficient for the advance angle. and This is the negative control coefficient for the advance angle.

7. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 4, characterized in that, Also includes: The calculation logic for the negative adjustment value of rail pressure: ,in, This is the negative adjustment value for rail pressure. and This is the negative adjustment coefficient for rail pressure. and This is the negative control coefficient for rail pressure.

8. The NOx emission control method for a non-road naturally aspirated diesel engine according to claim 4, characterized in that, It also includes: the calculation logic for the positive adjustment value of the advance angle: ,in, This is the positive adjustment value for the advance angle. and This is the positive adjustment coefficient for the advance angle. and This is the positive control coefficient for the advance angle.

9. A NOx emission control method for a non-road naturally aspirated diesel engine according to claim 4, characterized in that, Also includes: The calculation logic for the positive adjustment value of rail pressure: ,in, This is the positive adjustment value for rail pressure. and This is the positive adjustment value for rail pressure. and This is the positive control coefficient for rail pressure.

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