Low-pressure EGR target supercharger opening degree control method, supercharger and automobile

Abstract

The invention discloses a low-pressure EGR target supercharger opening degree control method, a supercharger and an automobile, and relates to the technical field of engines, the disclosed low-pressure EGR target supercharger opening degree control method comprises the steps that a feedforward coefficient of the supercharger opening degree is determined according to target supercharging pressure and an EGR rate weight coefficient of an engine, and when the engine meets a preset closed-loop condition, the feedforward coefficient of the supercharger opening degree is determined; pID control over the opening degree of the supercharger is conducted, in the PID control process of the opening degree of the supercharger, the PID control coefficient of the opening degree of the supercharger is determined according to the EGR rate weight coefficient of the engine, and control over the target opening degree of the supercharger is achieved by adjusting the feedforward coefficient and the PID control coefficient of the opening degree of the supercharger. Compared with the prior art, by adjusting the feed-forward coefficient and the PID control coefficient of the opening degree of the supercharger, the target opening degree of the supercharger is controlled in the acceleration and deceleration process and under the transient working condition that the EGR rate changes, and the power performance of an engine is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of engine technology, and in particular to a low-pressure EGR target supercharger opening control method, a supercharger and a vehicle. Background Art

[0002] In order to ensure the engine power performance and respond to the power output requested by the driver, the ECU (Electronic Control Unit) will convert the target requested torque into the target intake volume, and then convert the target intake volume into the target intake pressure, and then determine the throttle target opening and the supercharger target opening. Therefore, the setting of the supercharger target opening is an important part. In addition, for exhaust gas turbocharged engines, it is easier to set the target opening under steady-state conditions.

[0003] However, it is more difficult to set the target opening of the supercharger during acceleration and deceleration and in transient conditions where the EGR (Exhaust Gas Recirculation) rate changes. Summary of the invention

[0004] The main purpose of the present application is to provide a low-pressure EGR target supercharger opening control method, a supercharger and a vehicle, aiming to solve the technical problem that it is more difficult to set the target opening of the supercharger under transient conditions when the engine is accelerating or decelerating and the EGR rate changes.

[0005] To achieve the above object, the present application provides a low-pressure EGR target supercharger opening control method, the low-pressure EGR target supercharger opening control method comprising:

[0006] Determine the feedforward coefficient of the supercharger opening according to the target boost pressure and the engine's EGR rate weight coefficient;

[0007] When the engine meets the preset closed-loop conditions, PID control of the supercharger opening is performed;

[0008] In the PID control process of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the EGR rate weight coefficient of the engine;

[0009] The target opening degree of the supercharger is controlled by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening degree.

[0010] Optionally, the step of performing PID control of the supercharger opening when the engine meets a preset closed-loop condition specifically includes:

[0011] Get engine speed and supercharger inlet pressure;

[0012] When the engine speed is greater than the preset speed and the supercharger inlet pressure is greater than the preset pressure, PID control is performed.

[0013] Optionally, before the step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, the step further includes:

[0014] Determining a first pressure change according to the current intake pressure and a preset sampling period;

[0015] Determining an initial value of a target intake pressure according to the first pressure variation;

[0016] Determine the charging efficiency according to the initial value of the target intake pressure;

[0017] The target boost pressure is determined based on the charging efficiency and the engine's EGR rate weight coefficient.

[0018] Optionally, before the step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, the step further includes:

[0019] Get the actual EGR rate of the engine;

[0020] The EGR rate weight coefficient of the engine is determined based on the actual EGR rate and the target EGR rate of the engine.

[0021] Optionally, the step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine specifically includes:

[0022] Determine the feedforward compensation coefficient according to the target boost pressure and the engine ignition efficiency;

[0023] Determine the feedforward basic value according to the EGR rate weight coefficient of the engine and the ratio of the pressure before and after the supercharger;

[0024] The feedforward coefficient of the supercharger opening is determined based on the feedforward compensation coefficient and the feedforward basic value.

[0025] Optionally, in the PID control process of the supercharger opening, the step of determining the PID control coefficient of the supercharger opening according to the EGR rate weight coefficient of the engine specifically includes:

[0026] Determine the PID compensation coefficient according to the engine's EGR rate weight coefficient, the supercharger inlet pressure, and the supercharger outlet pressure;

[0027] According to the PID compensation coefficient and the difference between the target boost pressure and the actual boost pressure, the P term coefficient of the supercharger opening control is determined;

[0028] Determine the supercharger opening control I term coefficient according to the PID compensation coefficient, the target boost pressure change rate, and the target boost pressure and actual boost pressure difference change rate;

[0029] The D-term coefficient of the supercharger opening control is determined according to the PID compensation coefficient, the difference between the target boost pressure and the actual boost pressure, and the rate of change of the difference between the target boost pressure and the actual boost pressure.

[0030] Optionally, before the step of performing PID control of the supercharger opening when the engine meets the preset closed-loop condition, the method further includes:

[0031] When the engine does not meet the preset closed-loop condition, the supercharger opening control P item coefficient is set to the first preset value, the I item coefficient is set to the second preset value, and the D item coefficient is set to the third preset value.

[0032] In addition, to achieve the above-mentioned purpose, the present application also proposes a low-pressure EGR target supercharger opening control device, the device comprising:

[0033] A feedforward module, used for determining a feedforward coefficient of a supercharger opening according to a target boost pressure and an EGR rate weight coefficient of the engine;

[0034] A judgment module, used to perform PID control of the supercharger opening when the engine meets the preset closed-loop conditions;

[0035] A PID module is used to determine the PID control coefficient of the supercharger opening according to the EGR rate weight coefficient of the engine during the PID control process of the supercharger opening;

[0036] The opening control module is used to achieve the target opening control of the supercharger by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening.

[0037] In addition, to achieve the above-mentioned purpose, the present application also proposes a supercharger, which includes the low-pressure EGR target supercharger opening control method as described above.

[0038] In addition, to achieve the above-mentioned purpose, the present application also proposes a vehicle, which includes the low-pressure EGR target supercharger opening control method as described above.

[0039] One or more technical solutions proposed in this application have at least the following effects:

[0040] The present application determines the feedforward coefficient of the supercharger opening according to the target boost pressure and the weight coefficient of the engine's EGR rate, and performs PID control of the supercharger opening when the engine meets the preset closed-loop conditions. During the PID control process of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the engine's EGR rate weight coefficient, and the supercharger target opening control is achieved by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening. Compared with the prior art, the present application achieves supercharger target opening control during the acceleration and deceleration process and in transient conditions where the EGR rate changes by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening, thereby ensuring the engine power performance and responding to the power performance output requested by the driver in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0042] Figure 1 A schematic flow chart of a first embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application;

[0043] Figure 2 A flow chart of a second embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application;

[0044] Figure 3 A schematic flow chart of a third embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application;

[0045] Figure 4 A schematic flow chart of a fourth embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application;

[0046] Figure 5 A schematic flow chart of a fifth embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application;

[0047] Figure 6 This is a schematic diagram of the module structure of the low-pressure EGR target supercharger opening control device according to an embodiment of the present application;

[0048] Figure 7 This is an architecture diagram of the low-pressure EGR system proposed in an embodiment of the present application.

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

[0050] Description of Figure Numbers:

[0051] Label name Label name 10 Feedforward Module 20 Judgment module 30 PID Module 40 Opening control module DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0055] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0056] The main solution of the embodiment of the present application is: determine the feedforward coefficient and PID control coefficient of the supercharger opening according to the EGR rate weight coefficient, and achieve the supercharger target opening control by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening.

[0057] In this embodiment, for the convenience of description, the following description is made with ECU as the execution subject.

[0058] At present, in order to ensure the engine power performance and respond to the power output requested by the driver, the ECU will convert the target requested torque into the target intake volume, and then convert the target intake volume into the target intake pressure, and then determine the throttle target opening and the supercharger target opening. Therefore, the setting of the supercharger target opening is an important part. In addition, for exhaust gas turbocharged engines, it is easier to set the target opening under steady-state conditions, but it is more difficult to set the supercharger target opening under acceleration and deceleration and transient conditions where the EGR rate changes.

[0059] The present application provides a solution, which determines the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, and performs PID control of the supercharger opening when the engine meets the preset closed-loop conditions. During the PID control process of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the EGR rate weight coefficient of the engine. By adjusting the feedforward coefficient and the PID control coefficient of the supercharger opening, the supercharger target opening is controlled during the acceleration and deceleration process of the engine and under transient conditions where the EGR rate changes, thereby ensuring the engine power performance and promptly responding to the power output requested by the driver.

[0060] It should be noted that if Figure 7 As 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, an EGR differential pressure sensor and a linear oxygen sensor.

[0061] It should be noted that the supercharger compressor compresses fresh air for supercharging; the supercharger turbine controls the opening of the supercharger's exhaust bypass valve to control the turbine's working efficiency, thereby achieving different supercharging capabilities; among them, the low-pressure EGR system has additional components compared to the non-low-pressure EGR system, including: EGR cooler, EGR temperature sensor, EGR valve, EGR pressure difference sensor, mixing valve and oxygen sensor; 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.

[0062] It should be noted that the basic principle of supercharger opening control is: supercharger opening control is based on the engine's operating conditions and performance requirements, and changes the boost pressure by adjusting the opening of the supercharger bypass valve, thereby achieving precise control of the engine's intake volume. When the engine requires higher power output, the supercharger opening is reduced, the boost pressure increases, and the intake volume increases; conversely, when the engine power demand decreases, the supercharger opening is increased, the boost pressure decreases, and the intake volume decreases.

[0063] Based on this, an embodiment of the present application provides a low-pressure EGR target supercharger opening control method.

[0064] Reference Figure 1 , Figure 1 This is a flow chart of the first embodiment of the low-pressure EGR target supercharger opening control method proposed in the embodiment of the present application.

[0065] Considering the control of the supercharger target opening degree during the vehicle acceleration and deceleration process and the transient conditions of the EGR rate change, such as Figure 1 As shown, the low-pressure EGR target supercharger opening control method of this embodiment includes steps S10 to S40:

[0066] Step S10: Determine a feedforward coefficient of the supercharger opening according to the target supercharging pressure and the engine EGR rate weight coefficient.

[0067] It should be noted that under normal circumstances, the target boost pressure is equal to the target manifold intake pressure. The feedforward coefficient refers to feedforward control. Feedforward control is a method of responding to known disturbances or changes in a control system by precalculating and adjusting inputs.

[0068] Step S20: When the engine meets the preset closed-loop condition, PID control of the supercharger opening is performed.

[0069] It should be noted that PID (Proportional-Integral-Derivative) control achieves stable and precise control by continuously adjusting the output of the controller according to the difference between the measured value and the set value of the controlled object.

[0070] Step S30: During the PID control process of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the EGR rate weight coefficient of the engine.

[0071] It should be noted that the EGR rate weight coefficient is determined according to the ratio of the actual EGR rate to the target EGR rate.

[0072] Step S40: Achieve supercharger target opening control by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening.

[0073] In this embodiment, the ECU determines the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, and performs PID control of the supercharger opening when the engine meets the preset closed-loop conditions. During the PID control of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the EGR rate weight coefficient of the engine. By adjusting the feedforward coefficient and PID control coefficient of the supercharger opening, the supercharger target opening is controlled during the acceleration and deceleration process of the engine and under transient conditions where the EGR rate changes, thereby ensuring the engine power performance and promptly responding to the power output requested by the driver.

[0074] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the first embodiment can refer to the above introduction, and will not be repeated in the following. Figure 2 , Figure 2 This is a flow chart of a second embodiment of a low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application.

[0075] Considering the PID control of the supercharger opening when the closed-loop condition is met, the PID control coefficient is set when the closed-loop condition is not met, such as Figure 2 As shown, the step S20 specifically includes steps S21 to S22:

[0076] Step S21: Obtain the engine speed and the supercharger inlet pressure.

[0077] Step S22: When the engine speed is greater than a preset speed and the supercharger inlet pressure is greater than a preset pressure, PID control is performed.

[0078] It should be noted that the preset speed and the preset pressure can be set according to actual conditions, and this embodiment does not limit them.

[0079] In a specific implementation, the ECU obtains the engine speed and the supercharger inlet pressure, and performs PID control when the engine speed is greater than a preset speed and the supercharger inlet pressure is greater than a preset pressure, thereby achieving PID control of the supercharger opening.

[0080] Furthermore, before step S20, step S201 is also included:

[0081] Step S201: When the engine does not meet the preset closed-loop condition, the supercharger opening control P-item coefficient is set to a first preset value, the I-item coefficient is set to a second preset value, and the D-item coefficient is set to a third preset value.

[0082] It should be noted that the first preset value, the second preset value and the third preset value can be set according to actual conditions, and this embodiment does not limit this. For example, the first preset value is 0, the second preset value is 0, and the third preset value is 0.

[0083] In a specific implementation, when the engine does not meet the preset closed-loop condition, the supercharger opening control P item coefficient is set to a first preset value, the I item coefficient is set to a second preset value, and the D item coefficient is set to a third preset value.

[0084] Based on the second embodiment of the present application, in the third embodiment of the present application, the same or similar contents as those of the second embodiment can be referred to the above introduction, and will not be repeated in the following. Figure 3 , Figure 3 This is a flow chart of a third embodiment of the low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application.

[0085] The calculation taking into account the engine charging efficiency and the target boost pressure, such as Figure 3 As shown, before step S10, steps S101 to S104 are also included:

[0086] Step S101: determining a first pressure change according to the current intake pressure and a preset sampling period.

[0087] It should be noted that for the fresh air in the intake manifold, it is assumed that the temperature at the valve inlet of the manifold is constant during the intake process, the gas constant remains unchanged, and when the target intake density is constant, given that the charging efficiency of the intake system under transient conditions is not the only linear relationship with the target intake pressure. Based on the nonlinear relationship between the three, it is very difficult to solve the accuracy, and it is particularly important to find an approximate root of an equation. The Newton-Raphson iteration method is used to estimate the target intake pressure. The formula is:

[0088] f(p Des )=ρ Des RT-p Des V e (p Des )

[0089] f'(p Des )=-V e (p Des )-p Des ×dV e (p Des ) / dp Des

[0090] Where, dV e (p Des ) / dp Des V e (pDes ) Des Derivative, p Des is the target intake absolute pressure, V e (p Des ) is the charging efficiency, which is p Des The function of Des is the target inlet density, T is the inlet temperature, and R is the gas constant.

[0091] It should be noted that the selection of p 0 As p Des An initial approximation of 0 Take the estimated value of the actual intake pressure at the next moment, that is, p 0 =p c +Δp,p c is the actual value of the current intake pressure, Δp is the estimated actual pressure change at the next moment, and its estimation method is based on the evolution of Tustin transformation, and the formula is:

[0092]

[0093] In the formula, is the value of Δp at the previous sampling time, is the actual value of the intake pressure at the last sampling moment, Δt is the sampling period, t c is the time constant of the filter.

[0094] Step S102: Determine an initial value of the target intake pressure according to the first pressure change.

[0095] It should be noted that p Des The initial approximation p 0 The formula is:

[0096]

[0097] Pass point (p 0 , f(p 0 )) Draw a tangent line L to the curve y=f(p). The equation of L is y=f(p 0 )+f'(p 0 )(pp 0 ), find the horizontal coordinate p of the intersection point of L and the x-axis 1 =p 0 -f(p 0 ) / f'(p 0 ). Passing point (p 1 , f(p 1 )) Draw a tangent line to the curve y=f(p), and find the horizontal coordinate of the point where the tangent line intersects the x-axis, p2=p 1 -f(p 1 ) / f'(p1 ). Repeat the above process to get p n+1 =p n -f(p n ) / f'(p n ), where n is the number of iterations.

[0098] Step S103: Determine the charging efficiency according to the initial value of the target intake pressure.

[0099] It should be noted that the charging efficiency V e (p n ) is calculated as follows:

[0100]

[0101] Where K IC K is obtained by looking up the table based on the intake VVT ​​angle. EC According to the exhaust VVT angle table, p exh is the exhaust pipe pressure, n EngSpd is the engine speed, T coolant is the engine coolant temperature. e (p n ) is K IC , K EC , p exh , n eng and T coolant The bench is calibrated.

[0102] Step S104: Determine the target boost pressure according to the charging efficiency and the EGR rate weight coefficient of the engine.

[0103] It should be noted that in order to calculate V e (p n ) n The derivative of , introduces the array [p n -Δp c ,p n ,p n +Δp c ], where Δp c is the pressure difference constant, and V is obtained from formula 9 e (p n -Δp c ) and V e (p n +Δp c ), the formula is:

[0104]

[0105] Final pDesMap ≈p n+1 , target manifold intake pressurepDesMap The calculation formula is:

[0106]

[0107] Under normal circumstances, the target boost pressure is equal to the target manifold intake pressure. However, during the EGR transient change process, in order to obtain a smoother target boost pressure, the target boost pressure is corrected as follows:

[0108]

[0109] in is the coefficient after filtering, such as the formula:

[0110]

[0111] Where r ActEGRRatio is the actual EGR rate, r RefEGRRatio is the target EGR rate, d AirFlow is the intake constant, and Z is a constant.

[0112] In a specific implementation, a first pressure change is determined based on the current intake pressure and a preset sampling period, an initial value of a target intake pressure is determined based on the first pressure change, a charging efficiency is determined based on the initial value of the target intake pressure, and a target boost pressure is determined based on the charging efficiency and a weight coefficient of the engine's EGR rate, which is used to calculate a feedforward coefficient for the supercharger opening.

[0113] Furthermore, considering the calculation of the EGR rate weight coefficient of the engine, as Figure 3 As shown, before step S10, steps S105 to S106 are also included:

[0114] Step S105: Obtain the actual EGR rate of the engine.

[0115] Step S106: Determine the EGR rate weight coefficient of the engine according to the actual EGR rate and the target EGR rate of the engine.

[0116] It should be noted that the EGR rate weight coefficient of the engine is determined according to the ratio of the actual EGR rate to the target EGR rate.

[0117] In a specific implementation, the actual EGR rate of the engine is obtained, and the EGR rate weight coefficient of the engine is determined according to the actual EGR rate and the target EGR rate of the engine, which is used to calculate the feedforward coefficient and PID control coefficient of the supercharger opening.

[0118] Based on the third embodiment of the present application, in the fourth embodiment of the present application, the same or similar contents as those in the third embodiment can refer to the above introduction, and will not be repeated in the following. Figure 4 , Figure 4 This is a flow chart of a fourth embodiment of the low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application.

[0119] Considering the calculation of the feedforward coefficient of the supercharger opening, such as Figure 4 As shown, step S10 specifically includes steps S11 to S13:

[0120] Step S11: Determine a feedforward compensation coefficient according to the target boost pressure and the engine ignition efficiency.

[0121] It should be noted that since the feedforward table is set when all boost pressure is provided to the engine, when there is a pressure drop at the throttle, the intake manifold pressure is provided to the engine, and pressure difference compensation is required. At the same time, the feedforward is calibrated under the basic ignition angle condition. The de-ignition angle will cause the boost pressure to overshoot, and the actual ignition efficiency and final ignition efficiency need to be compensated. The calculation formula of the feedforward compensation coefficient is:

[0122]

[0123] Where r BaseEff is the basic ignition efficiency, r FinalEff is the final ignition efficiency, p DesMAP is the target intake pressure, p DesBoost is the target boost pressure, K EffComp is the compensation coefficient of ignition efficiency (can be calibrated), K AirComp is the compensation coefficient of intake air (calibrable).

[0124] Step S12: Determine a feedforward basic value according to the EGR rate weight coefficient of the engine and the ratio of the pressure before the supercharger and after the supercharger.

[0125] It should be noted that the basic value of the feedforward is obtained based on the engine speed, the pressure ratio between the supercharger outlet and the inlet, and the weight coefficient of the EGR rate. The calculation formula is:

[0126]

[0127] Where r PresRatio is the ratio of the pressure before and after the supercharger, f 1 (n EngSpd ,r PresRatio ) is the basic opening obtained according to the engine speed and pressure ratio, f 2 (n EngSpd ,r PresRatio ) is the opening degree with EGR rate obtained according to engine speed and compression ratio.

[0128] Step S13: Determine the feedforward coefficient of the supercharger opening according to the feedforward compensation coefficient and the feedforward basic value.

[0129] It should be noted that the feedforward coefficient formula of the supercharger opening is:

[0130] K FeedFinal =K FeedBase ×(1-K FeedComp )+K FeedBase

[0131] In this embodiment, the feedforward compensation coefficient is determined based on the target boost pressure and the engine ignition efficiency, the feedforward basic value is determined based on the ratio of the engine's EGR rate weight coefficient to the pressure before and after the supercharger, and the feedforward coefficient of the supercharger opening is determined based on the feedforward compensation coefficient and the feedforward basic value. By adjusting the feedforward coefficient of the supercharger opening, the target opening control of the supercharger is achieved.

[0132] Based on the fourth embodiment of the present application, in the fifth embodiment of the present application, the same or similar contents as those in the fourth embodiment can be referred to the above description, and will not be described in detail later. Figure 5 , Figure 5 This is a flow chart of a fifth embodiment of the low-pressure EGR target supercharger opening control method proposed in an embodiment of the present application.

[0133] Considering the control of the supercharger target opening during the vehicle acceleration and deceleration process and the transient conditions of the EGR rate change, such as Figure 5 As shown, the step S30 specifically includes steps S31 to S34:

[0134] Step S31: Determine the PID compensation coefficient according to the EGR rate weight coefficient of the engine, the supercharger inlet pressure and the supercharger outlet pressure.

[0135] It should be noted that the supercharger opening control adopts PID control, which consists of three parts: P, I and D. In order to perform PID control more accurately, the calculation formula of the PID compensation coefficient is:

[0136]

[0137] Where p CompInlet is the inlet pressure of the supercharger, f 3 (n Engspd ,r PresRatio ) is the coefficient obtained according to the engine speed and pressure ratio, f 4 (n Engspd ,r PresRatio ) is the coefficient of EGR rate obtained based on the speed and pressure ratio.

[0138] Step S32: Determine the supercharger opening control P term coefficient according to the PID compensation coefficient and the difference between the target boost pressure and the actual boost pressure.

[0139] It should be noted that the P-term coefficient formula for supercharger opening control is:

[0140] K BPc_P =f 5 (p PresErro ,n EngSpd )×p PresErro ×K PIDGain

[0141] Where p PresErro It is the difference between the target boost pressure and the actual boost pressure.

[0142] Step S33: Determine the supercharger opening control I coefficient according to the PID compensation coefficient, the target boost pressure change rate, and the change rate of the difference between the target boost pressure and the actual boost pressure.

[0143] It should be noted that the coefficient formula of the supercharger opening control I term is:

[0144] K BPc_I =f 6 (p PresErro ,n Engspd )×p PresErro ×K PIDGain ×f 7 (Δp PresErro ,n EngSpd )×f 8 (Δp DesPresErro )

[0145] Where Δp PresErro is the rate of change of the difference between the target boost pressure and the actual boost pressure, Δp DesPresErro is the target boost pressure change rate.

[0146] Step S34: Determine the D-term coefficient of the supercharger opening control according to the PID compensation coefficient, the difference between the target boost pressure and the actual boost pressure, and the rate of change of the difference between the target boost pressure and the actual boost pressure.

[0147] It should be noted that the D-term coefficient formula for supercharger opening control is:

[0148] K BPC_D =f 5 (p PresErro ,n EngSpd )×Δp PresErro ×K PIDGain

[0149] The supercharger target opening control calculation formula is as follows:

[0150] K BPC_D =K FeedFinal +K BPC_P +K BPC_I +K BPC_D

[0151] In this embodiment, the PID compensation coefficient is determined according to the EGR rate weight coefficient of the engine and the supercharger inlet pressure and the supercharger outlet pressure; the supercharger opening control P item coefficient is determined according to the PID compensation coefficient and the difference between the target boost pressure and the actual boost pressure; the supercharger opening control I item coefficient is determined according to the PID compensation coefficient, the target boost pressure change rate and the target boost pressure and actual boost pressure difference change rate; the supercharger opening control D item coefficient is determined according to the PID compensation coefficient, the target boost pressure and the actual boost pressure difference change rate; by adjusting the supercharger opening PID control coefficient, the supercharger target opening control is achieved during the acceleration and deceleration process of the vehicle and under transient conditions where the EGR rate changes, thereby ensuring the engine power performance and responding to the power performance output requested by the driver in a timely manner.

[0152] This application also provides a low-pressure EGR target supercharger opening control device, please refer to Figure 6 , Figure 6 This is a schematic diagram of the module structure of the low-pressure EGR target supercharger opening control device according to an embodiment of the present application, and the device includes:

[0153] A feedforward module 10, for determining a feedforward coefficient of a supercharger opening according to a target boost pressure and an EGR rate weight coefficient of the engine;

[0154] The judgment module 20 is used to perform PID control of the supercharger opening when the engine meets the preset closed-loop condition;

[0155] The PID module 30 is used to determine the PID control coefficient of the supercharger opening according to the EGR rate weight coefficient of the engine during the PID control process of the supercharger opening;

[0156] The opening control module 40 is used to achieve supercharger target opening control by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening.

[0157] To achieve the above objectives, the present application also proposes a supercharger, which includes the low-pressure EGR target supercharger opening control method as described above.

[0158] To achieve the above objectives, the present application also proposes a vehicle, which includes the low-pressure EGR target supercharger opening control method as described above.

[0159] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A low-pressure EGR target supercharger opening control method, characterized in that: The low-pressure EGR target supercharger opening control method comprises: Determine the feedforward coefficient of the supercharger opening according to the target boost pressure and the engine's EGR rate weight coefficient; When the engine meets the preset closed-loop conditions, PID control of the supercharger opening is performed; In the PID control process of the supercharger opening, the PID control coefficient of the supercharger opening is determined according to the EGR rate weight coefficient of the engine; The target opening degree of the supercharger is controlled by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening degree.

2. The low-pressure EGR target supercharger opening control method according to claim 1, characterized in that: The step of performing PID control of the supercharger opening when the engine meets the preset closed-loop condition specifically includes: Get engine speed and supercharger inlet pressure; When the engine speed is greater than the preset speed and the supercharger inlet pressure is greater than the preset pressure, PID control is performed.

3. The low-pressure EGR target supercharger opening control method according to claim 1, characterized in that: Before the step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, the method further includes: Determining a first pressure change according to the current intake pressure and a preset sampling period; Determining an initial value of a target intake pressure according to the first pressure variation; Determine the charging efficiency according to the initial value of the target intake pressure; The target boost pressure is determined based on the charging efficiency and the engine's EGR rate weight coefficient.

4. The low-pressure EGR target supercharger opening control method according to claim 1, characterized in that: Before the step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine, the method further includes: Get the actual EGR rate of the engine; The EGR rate weight coefficient of the engine is determined based on the actual EGR rate and the target EGR rate of the engine.

5. The low-pressure EGR target supercharger opening control method according to claim 3, characterized in that: The step of determining the feedforward coefficient of the supercharger opening according to the target boost pressure and the EGR rate weight coefficient of the engine specifically includes: Determine the feedforward compensation coefficient according to the target boost pressure and the engine ignition efficiency; Determine the feedforward basic value according to the EGR rate weight coefficient of the engine and the ratio of the pressure before and after the supercharger; The feedforward coefficient of the supercharger opening is determined based on the feedforward compensation coefficient and the feedforward basic value.

6. The low-pressure EGR target supercharger opening control method according to claim 1, characterized in that: The step of determining the PID control coefficient of the supercharger opening according to the EGR rate weight coefficient of the engine during the PID control process of the supercharger opening specifically includes: Determine the PID compensation coefficient according to the engine's EGR rate weight coefficient, the supercharger inlet pressure, and the supercharger outlet pressure; According to the PID compensation coefficient and the difference between the target boost pressure and the actual boost pressure, the P term coefficient of the supercharger opening control is determined; Determine the supercharger opening control I term coefficient according to the PID compensation coefficient, the target boost pressure change rate, and the target boost pressure and actual boost pressure difference change rate; The D-term coefficient of the supercharger opening control is determined according to the PID compensation coefficient, the difference between the target boost pressure and the actual boost pressure, and the rate of change of the difference between the target boost pressure and the actual boost pressure.

7. The low-pressure EGR target supercharger opening control method according to claim 1, characterized in that: Before the step of performing PID control of the supercharger opening when the engine meets the preset closed-loop condition, the method further includes: When the engine does not meet the preset closed-loop condition, the supercharger opening control P item coefficient is set to the first preset value, the I item coefficient is set to the second preset value, and the D item coefficient is set to the third preset value.

8. A low-pressure EGR target supercharger opening control device, characterized in that: The device comprises: A feedforward module, used for determining a feedforward coefficient of a supercharger opening according to a target boost pressure and an EGR rate weight coefficient of the engine; A judgment module, used to perform PID control of the supercharger opening when the engine meets the preset closed-loop conditions; A PID module is used to determine the PID control coefficient of the supercharger opening according to the EGR rate weight coefficient of the engine during the PID control process of the supercharger opening; The opening control module is used to achieve the target opening control of the supercharger by adjusting the feedforward coefficient and PID control coefficient of the supercharger opening.

9. A supercharger, characterized in that: The supercharger includes the low-pressure EGR target supercharger opening control method according to any one of claims 1 to 8.

10. An automobile, characterized in that: The vehicle includes the low-pressure EGR target supercharger opening control method according to any one of claims 1 to 8.

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