An engine protection control method and system based on cylinder combustion conditions

Abstract

The application discloses an engine protection control method and system based on cylinder combustion conditions, and the method comprises the following steps: periodically sampling the operation parameters of the engine; when it is judged that the EGR valve no longer satisfies the EGR closed loop enabling condition, determining the pressure ratio coefficient according to the actual pressure of the mixed valve outlet or inlet and the actual pressure of the throttle valve outlet or inlet; determining the initial value of the time length during which the target opening degree of the EGR valve remains unchanged according to the pressure ratio coefficient and the current engine real-time rotating speed; updating the residual time length value required for maintaining the target opening degree of the EGR valve unchanged at the current moment; self-learning and updating the residual time length value self-learning coefficient and the supercharger response time self-learning coefficient; performing secondary self-learning update on the residual time length value self-learning coefficient; and obtaining the final residual time length value during which the target opening degree of the EGR valve remains unchanged according to the residual time length value self-learning coefficient after the secondary self-learning update. The application can improve the engine knock protection and optimize the supercharging control response precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine control, in particular to an engine protection control method and system based on cylinder combustion conditions. BACKGROUND

[0002] Exhaust gas recirculation (EGR) takes exhaust gas from the exhaust system into the intake system. Studies have shown that the EGR system has certain advantages in improving emissions, reducing fuel consumption and improving anti-knock ability.

[0003] EGR closed-loop enabling conditions can be seen in patent CN118128651A "EGR valve target opening control method, device, equipment, medium and product", when the EGR closed-loop enabling conditions are met, the closed-loop control algorithm is used to control the action of the mixture valve and the EGR valve to realize the following of the EGR rate. When the EGR closed-loop enabling conditions are not met, how to set the EGR valve target opening becomes a problem to be solved, therefore, the present application proposes an engine protection control method and system based on cylinder combustion conditions from the aspects of knock and supercharging control accuracy. SUMMARY

[0004] The main purpose of the present application is to provide an engine protection control method and system based on cylinder combustion conditions, which protects the engine when the EGR closed-loop enabling conditions are not met.

[0005] The technical solution adopted by the present application is: an engine protection control method based on cylinder combustion conditions, comprising: periodically sampling the operating parameters of the engine; when it is judged that the EGR valve changes from meeting to not meeting the EGR closed-loop enabling conditions, determining a pressure ratio coefficient according to the actual pressure at the outlet or inlet of the mixture valve and the actual pressure at the outlet or inlet of the throttle valve;

[0006] determining an initial value of the time length during which the EGR valve target opening is maintained unchanged according to the pressure ratio coefficient and the current engine real-time speed;

[0007] updating the remaining time length value during the process of maintaining the EGR valve target opening unchanged according to the mixture valve outlet pressure change, the correction coefficient determined based on the number of knocks, the time length self-learning update coefficient, and the difference fluctuation between the target supercharging pressure and the actual supercharging pressure;

[0008] self-learning updating the remaining time length value self-learning coefficient and the supercharger response time self-learning coefficient based on the difference between the updated remaining time length value and the initial remaining time length value, and the mixture valve outlet pressure change;

[0009] secondarily self-learning updating the remaining time length value self-learning coefficient based on the difference between the updated remaining time length value and the initial remaining time length value, and the number of knocks of different knock intensities;

[0010] The final residual duration value is obtained according to the self-learning coefficient of the updated residual duration value after the secondary self-learning, and the target opening degree of the EGR valve is maintained unchanged.

[0011] According to the technical solution, the pressure ratio coefficient is the product of the ratio of the actual pressure at the outlet of the mixing valve to the actual pressure at the inlet of the mixing valve and a pressure ratio coefficient correction coefficient, and the pressure ratio coefficient correction coefficient is calibrated from the ratio of the actual pressure at the outlet of the throttle valve to the actual pressure at the inlet of the throttle valve under the calibration condition of the pressure ratio coefficient correction coefficient.

[0012] The calibration condition of the pressure ratio coefficient correction coefficient includes that, from the first sampling period when the EGR closed loop enabling condition is not met to the sampling period when the initial duration value ends, under the condition that the target supercharging pressure is unchanged, the fluctuation of the difference between the target supercharging pressure and the actual supercharging pressure is within a preset range.

[0013] According to the technical solution, the sampling period when the initial duration value ends is determined by the updated supercharger response time, and the updated supercharger response time τ = τ Boost × (1 + r Boost ), wherein τ Boost is the initial supercharger response time, and r Boost is a supercharger response time self-learning coefficient, and the default value is 0.

[0014] The method for obtaining the initial supercharger response time τ Boost includes setting different EGR rates under different engine speeds and different actual intake densities of the cylinder, and obtaining the average value of the supercharger response time by sampling data multiple times.

[0015] According to the technical solution, the judgment basis that the fluctuation of the difference between the target supercharging pressure and the actual supercharging pressure is within a preset range is that, under the premise that p

[0016] p BoostErrFilter (N) = K BoostErr × [p BoostErr (N) - p BoostErrFilter (N-1)] + p BoostErrFilter (N-1), from the first sampling period when the EGR closed loop enabling condition is not met to the sampling period when the initial duration value ends, |p BoostErrFliter (N) - p BoostErr (N) < min[p BoostErr (N), p BoostErrFliter (N)] × r BoostErrLim is met, wherein p BoostErrFilter (N) is the first-order low-pass filtered pressure difference in the Nth sampling period, m is the number of engine cylinders, n is the engine speed, and kBoostErr p is a preset pressure difference filtering coefficient BoostErr (N) is the pressure difference p of the Nth sampling period BoostErr p is an original value BoostErrFilter (N-1) is the first-order low-pass filtered pressure difference r of the N-1th sampling period BoostErrLim p is a preset limit coefficient

[0017] According to the technical scheme, the method for obtaining the mixed valve outlet pressure change amount specifically comprises: calculating the quotient of the initial supercharger response time and the preset sampling period, and taking the difference between the maximum value and the minimum value of the mixed valve outlet pressure in the sampling period corresponding to the quotient value.

[0018] According to the technical scheme, the method for updating the remaining duration value comprises: updating the remaining duration value t1' = t1 × (1 + k Knock ) × [1 + f(Δp AfMixAct , Δp BoostErr )] × (1 + r t1 );

[0019] Wherein, k Knock is a correction coefficient calibrated based on the number of knockings, k Knock = f(r PreRatio , Cnt LowKnock ) × f(r PreRatio , Cnt MediumKnock ) × f(r PreRatio , Cnt HighKnock ), and the calibration is based on the fact that, within a period of time after the updated remaining duration value ends and delays for a preset time, the fluctuation of the difference between the target supercharging pressure and the actual supercharging pressure is within a preset range, and only low-intensity knockings below a preset number occur in the cylinder; Δp AfMixAct is a mixed valve outlet pressure change amount, Δp BoostErr is a fluctuation of the difference between the target supercharging pressure and the actual supercharging pressure, and the calibration of f(Δp AfMixAct , Δp BoostErr ) is based on the fact that the fluctuation of the difference between the target supercharging pressure and the actual supercharging pressure p BoostErr is within a preset range; and r t1 is a remaining duration value self-learning coefficient.

[0020] According to the technical scheme, the method for initially self-learning updating the duration self-learning updating coefficient and the supercharger response time self-learning coefficient specifically comprises:

[0021] calculating the difference between the updated remaining duration value and the initial remaining duration value;

[0022] determine the state of the current working condition according to the difference between the updated residual duration value and the initial residual duration value; the state includes upward learning state one, upward learning state two, downward learning state one, downward learning state two and other state;

[0023] If the current working condition is in the upward learning state, the residual duration value self-learning coefficient is increased; if the current working condition is in the downward learning state, the residual duration value self-learning coefficient is decreased; and if the current working condition is in the other state, the residual duration value self-learning coefficient is not updated.

[0024] According to the above technical solution, the specific method for determining the state of the current working condition includes:

[0025] If the difference between the updated residual duration value and the initial residual duration value is greater than the preset value C1 for more than the preset number of times CNT1, it is determined that the current working condition is in the upward learning state one; if the difference between the updated residual duration value and the initial residual duration value is greater than the preset value C1, and the difference between the updated residual duration value and the initial residual duration value in the last self-learning process is not greater than the preset value C2, it is determined that the current working condition is in the upward learning state two.

[0026] If the difference between the updated residual duration value and the initial residual duration value is greater than the preset value C2 for more than the preset number of times CNT2, it is determined that the current working condition is in the downward learning state one; if the difference between the updated residual duration value and the initial residual duration value is greater than the preset value C2, and the difference between the updated residual duration value and the initial residual duration value in the last self-learning process is not greater than the preset value C1, it is determined that the current working condition is in the downward learning state two.

[0027] In the remaining case, it is determined to be in the other state.

[0028] According to the above technical solution, when the current working condition belongs to the upward learning state one, if the number of times that the mixed valve outlet pressure change amount exceeds the preset value A1 exceeds the preset number of times CNT1, the supercharger response time self-learning coefficient is increased by the preset value X1, and it is determined that the current working condition belongs to the vice upward learning state one; if the current working condition belongs to the downward learning state one, if the number of times that the mixed valve outlet pressure change amount exceeds the preset value A2 exceeds the preset number of times CNT2, the supercharger response time self-learning coefficient is reduced by the preset value X2, and it is determined that the current working condition belongs to the vice downward learning state one.

[0029] According to the above technical solution, in each self-learning update process, if the supercharger response time self-learning coefficient is updated, CNT1 and CNT2 are cleared.

[0030] According to the technical solution, the priority of the secondary upward learning state one, the upward learning state one, the secondary downward learning state one, the downward learning state one, the upward learning state two, the downward learning state two and other working conditions is sequentially reduced, and if it is judged that the current working condition is in a state with high priority, the state with low priority is not judged.

[0031] According to the technical solution, the method for updating the secondary self-learning includes:

[0032] According to the difference between the updated residual duration value and the initial residual duration value and the knock frequency of different knock intensities, the state of the current working condition is judged.

[0033] The state includes the upward high-knock learning state one, the upward medium-knock learning state one, the upward low-knock learning state one, the upward knock learning state one, the downward high-knock learning state one, the downward medium-knock learning state one, the downward low-knock learning state one, the downward knock learning state one and other states.

[0034] If the current working condition is in an upward learning state, the residual duration value self-learning coefficient is increased; if the current working condition is in a downward learning state, the residual duration value self-learning coefficient is reduced; and if the current working condition is in other states, the residual duration value self-learning coefficient is not updated.

[0035] According to the technical solution, the method for judging the state of the current working condition specifically includes:

[0036] If the knock frequency of high-knock intensity exceeds the preset number CNT3, the residual duration value self-learning coefficient is increased by a preset value X3, it is judged that the current working condition is in the upward high-knock learning state one, and the current working condition satisfies the condition that the difference between the updated residual duration value and the initial residual duration value is greater than a preset value C1; if the knock frequency of medium-knock intensity exceeds the preset number CNT4, the residual duration value self-learning coefficient is increased by a preset value X4, it is judged that the current working condition is in the upward medium-knock learning state one, and the current working condition satisfies the condition that the difference between the updated residual duration value and the initial residual duration value is greater than a preset value C1; if the knock frequency of low-knock intensity exceeds the preset number CNT5, the residual duration value self-learning coefficient is increased by a preset value X5, it is judged that the current working condition is in the upward low-knock learning state one, and the current working condition satisfies the condition that the difference between the updated residual duration value and the initial residual duration value is greater than a preset value C1; if the number of times that the current working condition satisfies the condition that the difference between the updated residual duration value and the initial residual duration value is greater than a preset value C1 exceeds a preset number CNT6, the residual duration value self-learning coefficient is increased by a preset value X6, it is judged that the current working condition is in the upward knock learning state one.

[0037] In the current working condition, if the number of knock of high knock intensity exceeds the preset number A6 by more than the preset number CNT7, the remaining duration value self-learning coefficient is reduced by the preset value X7, and it is judged that the current working condition is in a downward high knock learning state I; if the number of knock of medium knock intensity exceeds the preset number A7 by more than the preset number CNT8, the remaining duration value self-learning coefficient is reduced by the preset value X8, and it is judged that the current working condition is in a downward medium knock learning state I; if the number of knock of low knock intensity exceeds the preset number A8 by more than the preset number CNT9, the remaining duration value self-learning coefficient is reduced by the preset value X9, and it is judged that the current working condition is in a downward low knock learning state I; if the number of times that the difference between the updated remaining duration value and the initial remaining duration value is not more than the preset value C2 exceeds the preset number CNT 10 , the remaining duration value self-learning coefficient is reduced by the preset value X 10 , and it is judged that the current working condition is in a downward knock learning state I.

[0038] In other cases, the remaining duration value self-learning coefficient is not updated.

[0039] According to the above technical solution, in each self-learning update process, if the supercharger response time self-learning coefficient is updated, CNT3, CNT4, CNT5, CNT6, CNT7, CNT8, CNT9, CNT 10 are cleared.

[0040] According to the above technical solution, the priority of the upward high knock learning state I, the upward medium knock learning state I, the upward low knock learning state I, the upward knock learning state I, the downward high knock learning state I, the downward medium knock learning state I, the downward low knock learning state I, the downward knock learning state I, and other states decreases in turn, and if it is judged that the current working condition is in a state with high priority, the states with low priority are not judged.

[0041] Another aspect of the present application provides an engine protection control system based on cylinder combustion conditions, which executes the above-mentioned engine protection control method based on cylinder combustion conditions.

[0042] The present application has the advantages that the present application provides an engine protection control method and system based on cylinder combustion conditions, when the EGR valve does not meet the EGR closed loop enabling condition, an initial value of the duration during which the EGR valve target opening degree is maintained is determined, and the remaining duration value is updated during the process in which the EGR valve target opening degree is maintained based on the mixed valve outlet pressure change amount and the number of knocks of different knock intensities. The present application optimizes the control of the EGR valve target opening degree after the EGR closed loop enabling condition is exited, improves the engine knock protection, and optimizes the response accuracy of the supercharging control.

[0043] Of course, implementing any product of the present application does not necessarily require that all of the above-mentioned advantages be achieved simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0045] Figure 1 is a flow chart of the engine protection control method based on cylinder combustion condition of the embodiment of the present application;

[0046] Figure 2 is a logic diagram of the engine protection control method based on cylinder combustion condition of the embodiment of the present application;

[0047] Figure 3 is a structure diagram of the engine protection control system based on cylinder combustion condition of the embodiment of the present application.

[0048] Reference signs: 1, air filter; 2, mixing valve; 3, compressor; 4, throttle valve; 5, engine; 6, turbine; 7, catalytic converter; 8, particulate trap; 9, EGR cooler; 10, EGR valve; 11, temperature sensor; 12, differential pressure sensor. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, the following will further describe the present application in combination with the drawings and embodiments. 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.

[0050] It should be noted that the diagrams provided in the embodiments of the present application only illustrate the basic concept of the present application in a schematic manner, and therefore only show the components related to the present application in the diagrams, not the number, shape and size of the components when actually implemented. The shape, number and proportion of each component when actually implemented can be arbitrarily changed, and the layout pattern of the components can also be more complex.

[0051] In this invention, it should also be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used only for descriptive and distinguishing purposes and should not be construed as indicating or implying relative importance.

[0052] Example 1

[0053] This embodiment provides an engine protection control method based on cylinder combustion conditions, the process of which is as follows: Figure 1 As shown, the steps include:

[0054] S1. Periodically sample the engine's operating parameters to determine when the EGR valve changes from meeting to not meeting the EGR closed-loop enable condition, based on the actual outlet pressure p of the mixing valve. AfMixAct Actual pressure p at the inlet of the mixing valve BfMixAct Actual throttle outlet pressure p AfThrAct and the actual pressure p at the throttle inlet BfMixAct Determine the pressure ratio coefficient.

[0055] S101. Determine whether the EGR valve meets the EGR closed-loop enabling conditions. The specific EGR closed-loop enabling conditions can be found in patent CN118128651A "Target Opening Control Method, Device, Equipment, Medium and Product of EGR Valve".

[0056] Specifically, it determines whether the current operating condition is one where the EGR closed-loop enable condition was met in the previous sampling period, and the current sampling period is one where the EGR closed-loop enable condition is not met. In this example, the sampling period is 10ms.

[0057] S102, Based on the actual outlet pressure p of the mixing valve AfMixAct The actual pressure p at the inlet of the mixing valve BfMixAct ratio Actual throttle outlet pressure p AfThrAct With the actual pressure p at the throttle inlet BfMixAct ratio Together they determine the pressure ratio coefficient r PreRatio .

[0058] Specifically, This is the correction factor for the pressure ratio coefficient, and The larger the throttle body, the worse the throttle control capability, and the greater the risk to the turbocharger's pressure control accuracy. Therefore, to avoid turbocharger pressure control accuracy problems, [the following measures should be taken]... Calibration improvement is made. The calibration parameters are shown in Table 1.

[0059]

[0060] Table 1

[0061] S2, according to the pressure ratio coefficient r PreRatio and the current engine real-time speed n, determine the initial value of the time length during which the EGR valve target opening degree is maintained unchanged. The purpose of maintaining the EGR valve target opening degree unchanged is to maintain the stability of the EGR valve and avoid the influence of the supercharging inlet pressure on the supercharging control responsiveness. That is, the EGR valve target opening degree pct EGRDsrd (z) is determined. EGRDsrd The time length during which pct EGRDsrd (z) is the EGR valve target opening degree in the last sampling period, i.e., the EGR valve target opening degree when the EGR closed-loop condition is satisfied in the last sampling period. The initial value of the time length t is counted from the first sampling period in which the EGR closed-loop condition is not satisfied.

[0062] S201, determine whether the initial value of the time length meets the calibration condition.

[0063] Specifically, the determination basis is that, under the condition that the target supercharging pressure is fixed and unchanged, pct BoostErrFilter (N) = K BoostErr × [p BoostErr (N) - p BoostErrFilter (N-1)] + p BoostErrFilter (N-1) is satisfied in N Boost sampling periods from the first sampling period in which the EGR closed-loop enabling condition is not satisfied to the end of the initial value of the time length t. BoostFilter That is, |p BoostErr (N) - p BoostErr (N)| < min[p BoostErrFliter (N), p BoostErrLim (N)] × r .

[0064] The value of N Boost depends on the supercharger response time τ = τ Boost × (1 + r Boost ), wherein r Boost is a self-learning coefficient of the initial supercharger response time τ Boost , which has a default value of 0 and can be saved after the vehicle is powered off. The initial supercharger response time τ Boost is the time for the mixture to flow from the supercharger compressor to the throttle outlet, which can be obtained by setting different EGR rates and averaging multiple sampling data at different engine speeds n eng and different actual intake densities rho Act of the cylinder.

[0065] Where, p BoostErrFilter (N) represents the pressure difference after first-order low-pass filtering in the Nth sampling period. m is the number of engine cylinders, n is the engine speed, and k is the engine speed. BoostErr p is the preset pressure difference filter coefficient. BoostErr (N) represents the pressure difference p during the Nth sampling period. BoostErr Original value, p BoostErrFilter (N-1) represents the pressure difference after first-order low-pass filtering in the (N-1)th sampling period, r BoostErrLim The preset limit coefficient is 0.1 in this embodiment.

[0066] S202. Under the premise of meeting the initial value calibration conditions for duration, calibrate the initial value t of duration.

[0067] Specifically, the initial value of duration t = f(r) PreRatio ,n), and pressure ratio coefficient r PreRatio It is directly proportional to the engine's actual speed n, and inversely proportional to the difference p between the target boost pressure and the actual boost pressure. BoostErr The fluctuation is within the preset range. Under the condition that the actual engine speed n is the same, if the pressure ratio coefficient r... PreRatio The smaller the value, the smaller the initial duration t; in the pressure ratio coefficient r PreRatio Under the same conditions, the smaller the rotational speed n, the larger the initial value of the duration t.

[0068] S3, Based on the change in outlet pressure Δp of the mixing valve AfMixAct Self-learning update coefficient r for the number of detonations and duration at different detonation intensities t1 While maintaining the target opening degree of the EGR valve, the remaining time value t1 is updated. Excessive changes in the mixing valve outlet pressure Δp... AfMixAct This will have a detrimental impact on the stability of boost control, which in turn will affect the stability of subsequent boost pressure control. Therefore, the change in the mixing valve outlet pressure Δp needs to be considered in this step. AfMixAct Preferably, the remaining duration value t1 is limited to the maximum value t. max and minimum value t min To avoid excessive adjustment that could lead to poor robustness of the intake system control, in this embodiment, t max Take 0.2s, t min Take 0s.

[0069] S301, Obtain the change in outlet pressure Δp of the mixing valve. AfMixAct and the correction coefficient k determined based on the number of detonations Knock .

[0070] Specifically, the change in outlet pressure of the mixing valve ΔpAfMixAct the most recent the mixed valve outlet pressure p in the sub-sampling period AfMixAct the maximum value and the mixed valve outlet pressure p AfMixAct the difference between the maximum value and the minimum value.

[0071] if the mixed valve outlet pressure p AfMixAct the mixed valve outlet pressure change Δp is positive if the time at which the maximum value occurs is later than the time at which the mixed valve outlet pressure p AfMixAct the minimum value occurs. AfMixAct is positive; if the mixed valve outlet pressure p AfMixAct the mixed valve outlet pressure change Δp is negative if the time at which the maximum value occurs is earlier than the time at which the mixed valve outlet pressure p AfMixAct the minimum value occurs. AfMixAct is negative; if the mixed valve outlet pressure p AfMixAct the maximum value and the mixed valve outlet pressure p AfMixAct the minimum value occur simultaneously, the mixed valve outlet pressure change Δp AfMixAct is 0.

[0072] k Knock is a correction coefficient determined based on the knock frequency and the pressure ratio coefficient r PreRatio under different knock intensities, k Knock = f(r PreRatio , Cnt LowKnock ) x f(r PreRatio , Cnt MediumKnock ) x f(r PreRatio , Cnt HighKnock ), under the condition that the fluctuation of the difference p BoostErr between the target boost pressure and the actual boost pressure is within a preset range, k Knock is calibrated so as to meet the condition that a period of time after t1' ends and a preset time τ EGR is delayed, i.e. a period of time in which the engine completes 20 working cycles, 1 working cycle being defined as the engine completing 4 working strokes in each cylinder, and at most a preset number of low-intensity knockings occur, in this embodiment, 5, τ EGR is the time for exhaust gas to flow from the EGR valve to the cylinder, which can be obtained by averaging the data obtained by setting different EGR rates and sampling multiple times under different engine speeds n eng and different actual intake densities rho Act into the cylinder.

[0073] Under the condition that the knock frequencies Cnt LowKnock , Cnt MediumKnock , Cnt HighKnock remain unchanged, the smaller the pressure ratio coefficient r PreRatio , the smaller the correction coefficient k Knock determined based on the knock frequency under different knock intensities.The smaller the value, the better the pressure ratio coefficient r. PreRatio Under the same conditions, the number of detonation events (Cnt) LowKnock Cnt MediumKnock Cnt HighKnock The larger f(r) is, the better. PreRatio Δ EGRRatioErr The larger the value, the more it can suppress the occurrence of detonation.

[0074] S302. Under the premise of meeting the calibration criteria, complete f(Δp) AfMixAct Δp BoostErr ) calibration.

[0075] f(Δp AfMixAct Δp BoostErr The calibration basis is that, under the condition of satisfying the difference p between the target boost pressure and the actual boost pressure... BoostErr Under the premise that the fluctuation is within the preset range, the change in boost pressure difference Δp BoostErr Under the same conditions, the mixing valve outlet pressure p AfMixAct Change Δp AfMixAct The smaller f(Δp) is, the better. AfMixAct , Δp BoostErr The smaller the value, the better; at the mixing valve outlet pressure p AfMixAct Change Δp AfMixAct Under the same conditions, if the change in boost pressure difference Δp BoostErr The larger the value, the greater the value of f(Δp). AfMixAct Δp BoostErr The larger it is.

[0076] S4. The difference between the updated remaining time value t1' and the initial remaining time value t1, and the change in mixing valve outlet pressure Δp. AfMixAct The self-learning update coefficient r for duration t1 The self-learning coefficient r of the turbocharger response time Boost It performs self-learning updates.

[0077] The following conditions are checked sequentially, from highest to lowest priority. If a high-priority condition is met, the low-priority condition is no longer checked.

[0078] (1) Secondary upward learning state one: If t1'-t1 is greater than the preset value C1, which is 0.1s in this example, it indicates that the adjustment is too large due to the excessive fluctuation of the boost pressure difference, and Δp AfMixAct If the pressure difference exceeds the preset value A1 (±20 kPa in this example) and the number of consecutive occurrences exceeds the preset number CNT1 (5 in this embodiment), it indicates that the pressure difference causes the duration t1 to continuously increase. To reduce the impact of pressure difference fluctuations, r... t1 =r t1 (z)+0.05, r Boost= r Boost (z) + 0.1, where r t1 (z) is the time t1learned value stored last time learning, r Boost (z) is the r Boost learned value stored last time learning. CNT1 is cleared at the same time. The new learned value stored is used next time this kind of situation is judged. CNT1 is updated at most once in each driving cycle.

[0079] (2) Upward learning state one: if t1'-t1 is greater than preset value C1, 0.1s in this embodiment, it is indicated that the adjustment caused by the excessive fluctuation of the supercharging pressure difference is too large, and the number of continuous occurrences exceeds preset number CNT1, 5 in this embodiment, it is indicated that the influence of the supercharging pressure difference causes the time t1 to increase all the time, in order to reduce the influence of the fluctuation of the supercharging pressure difference, r t1 = r t1 (z) + 0.03. CNT1 is cleared at the same time. The new learned value stored is used next time this kind of situation is judged. CNT1 is updated at most once in each driving cycle.

[0080] (3) Subordinate downward learning state one: if t1'-t1 is not greater than preset value C2, -0.1s in this embodiment, it is indicated that the adjustment caused by the excessive fluctuation of the supercharging pressure difference is too large, and Δp AfMixAct exceeds preset value A2, ±20kPa in this embodiment, and the number of continuous occurrences exceeds preset number CNT2, it is indicated that the influence of the supercharging pressure difference causes the time t1 to decrease all the time, in order to reduce the influence of the fluctuation of the supercharging pressure difference, r t1 = r t1 (z) - 0.02, r Boost = r Boost (z) - 0.1. CNT2 is cleared at the same time. The new learned value stored is used next time this kind of situation is judged. CNT2 is updated at most once in each driving cycle.

[0081] (4) Downward learning state one: if t1'-t1 is not greater than preset value C2, -0.1s in this embodiment, it is indicated that the adjustment caused by the excessive fluctuation of the supercharging pressure difference is too large, and the number of continuous occurrences exceeds preset number CNT2, it is indicated that the influence of the supercharging pressure difference causes the time t1 to decrease all the time, in order to reduce the influence of the fluctuation of the supercharging pressure difference, r t1 = r t1 (z) - 0.04. CNT2 is cleared at the same time. The new learned value stored is used next time this kind of situation is judged. CNT2 is updated at most once in each driving cycle.

[0082] (5) Upward learning state two: if t1'-t1 is greater than preset value C1, which is 0.1s in this example, and t1'-t1 is not greater than preset value C2 in the last self-learning process, the fluctuation is adjusted to be too large, at this time, the pressure fluctuation has a greater impact, then r t1 t1 (z)+0.02. The newly learned storage learning value is used next time when entering this kind of situation.

[0083] (6) Downward learning state two: if t1'-t1 is greater than preset value C2, which is -0.1s in this example, and t1'-t1 is not greater than preset value C1 in the last self-learning process, the fluctuation is adjusted to be too large, at this time, the pressure fluctuation has a greater impact, then r t1 t1 (z)-0.02. The newly learned storage learning value is used next time when entering this kind of situation.

[0084] (7) Other states that do not meet the above states, r t1 and r Boost remain unchanged.

[0085] S5, after completing the initial self-learning update, based on the difference between the remaining duration value and the initial duration value, and the knock frequency of different knock intensities, the duration self-learning update coefficient is secondarily self-learned and updated.

[0086] In turn, it is judged whether the current working condition meets the following conditions, the priority is from high to low, and when the high-priority state is met, the low-priority state is no longer judged.

[0087] (1) Upward high knock learning state one: if t1'-t1 is greater than preset value C1, which is 0.1s in this example, and the knock frequency Cnt HighKnock of high knock intensity exceeds preset value A3, which is 5 in this example, and the number of continuous occurrences exceeds preset number CNT3, which is 5 in this example, it is indicated that the influence of knock protection causes the duration t1 to always increase, in order to suppress the influence of engine knock, r t1 t1 (z)+0.05, and CNT3 is cleared. The newly learned storage learning value is used next time when entering this kind of situation. CNT3 is updated at most once in each driving cycle.

[0088] (2) Upward medium knock learning state one: if t1'-t1 is greater than preset value C1, which is 0.1s in this example, and the knock frequency Cnt MediumKnock of medium knock intensity exceeds preset value A4, which is 5 in this example, and the number of continuous occurrences exceeds preset number CNT4, which is 5 in this example, it is indicated that the influence of knock protection causes the duration t1 to always increase, in order to suppress the influence of engine knock, r t1 ​​​=r t1 (z) + 0.025, and simultaneously clear CNT4 to zero. The newly learned value is used the next time this condition is entered. CNT4 is updated at most once during each driving cycle.

[0089] (3) Upward low-detonation learning state one: If t1'-t1 is greater than the preset value C1, this example takes 0.1s, and the number of detonations of low-detonation intensity Cnt LowKnock If the value exceeds the preset value A5 (5 in this example), and the number of consecutive occurrences exceeds the preset number CNT5 (5 in this example), it indicates that the knock protection causes the duration t1 to continuously increase. To suppress the influence of engine knock, r t1 =r t1 (z) + 0.01, and simultaneously clear CNT5 to zero. The newly learned value is used the next time this condition is entered. CNT5 is updated at most once during each driving cycle.

[0090] (4) Upward detonation learning state one: If t1'-t1 is greater than the preset value C1, this example takes 0.1s, and the number of consecutive occurrences exceeds the preset number CNT6, this example takes 5, r t1 =r t1 (z) + 0.005, and simultaneously clear CNT6 to zero. The newly learned value will be used the next time this condition is entered. CNT6 will be updated at most once during each driving cycle.

[0091] (5) Downward high detonation learning state one: If t1'-t1 is greater than the preset value C2, this example takes -0.1s, and the number of high detonation intensity detonations Cnt HighKnock If the value exceeds the preset value A6 (5 in this example) and the number of consecutive occurrences exceeds the preset number CNT7 (5 in this example), it indicates that the knock protection causes the duration t1 to continuously increase. To suppress the effect of engine knock, r t1 =r t1 (z)-0.02, and simultaneously clear CNT7. The newly learned value is used the next time this condition is entered. CNT7 is updated at most once during each driving cycle.

[0092] (6) Downward detonation learning state one: If t1'-t1 is greater than the preset value C2, this example takes -0.1s, and the number of detonations of the intermediate detonation intensity Cnt MediumKnock If the value exceeds the preset value A7 (5 in this example) and the number of consecutive occurrences exceeds the preset number CNT8 (5 in this example), it indicates that the knock protection causes the duration t1 to continuously increase. To suppress the influence of engine knock, r t1 =r t1(z) -0.03, and CNT8 is cleared at the same time. The newly learned storage learning value is used next time when entering this kind of situation judgment. CNT8 is updated at most once during each driving cycle.

[0093] (7) Downward low knock learning state one: if t1'-t1 is greater than preset value C2, the present example takes -0.1s, and the number of knock of low knock intensity CNT LowKnock exceeds preset value A8, the present example takes 5, and the number of continuous occurrence exceeds preset number CNT9, the present example takes 5, which indicates that the influence of knock protection causes the length t1 to increase all the time. In order to suppress the influence of engine knock, r t1 = r t1 (z) -0.04, and CNT9 is cleared at the same time. The newly learned storage learning value is used next time when entering this kind of situation judgment. CNT9 is updated at most once during each driving cycle.

[0094] (8) Downward knock learning state one: if t1'-t1 is greater than preset value C2, the present example takes -0.1s, and the number of continuous occurrence exceeds preset number CNT 10 , the present example takes 5, r t1 = r t1 (z) -0.07, and CNT 10 is cleared at the same time. The newly learned storage learning value is used next time when entering this kind of situation judgment. CNT 10 is updated at most once during each driving cycle.

[0095] (9) Other state not satisfying the above states, r t1 remains unchanged.

[0096] S6, the final remaining length value of EGR valve target opening degree maintaining unchanged is obtained according to the self-learning updated coefficient of the length.

[0097] Specifically, the final remaining length value of EGR valve target opening degree maintaining unchanged is calculated based on the calculation formula

[0098] t1' = t1 x (1+k Knock ) x [1+f(Δp AfMixAct , Δp BoostErr )] x (1+r t1 ) and the self-learning updated r t1 .

[0099] In summary, the method logic of the present embodiment is as follows Figure 2As shown, based on the basic setting of maintaining the EGR valve opening unchanged after the EGR closed loop enabling condition exits, the initial value of the time length of maintaining the EGR valve opening unchanged is determined, and in the maintaining process, the remaining maintaining time length is optimized based on the occurrence of different levels of knock and the supercharging response, so that the final EGR valve opening maintaining time of the EGR closed loop enabling exit is obtained, and the improvement of engine knock protection and supercharging control response accuracy is realized.

[0100] Embodiment 2

[0101] The embodiment provides an engine protection control system based on cylinder combustion conditions, the system executes the engine protection control method based on cylinder combustion conditions described in embodiment 1, and the structure is as shown in Figure 3 The embodiment provides an engine protection control system based on cylinder combustion conditions, the system executes the engine protection control method based on cylinder combustion conditions described in embodiment 1, and the structure is as shown in

[0102] In summary, the application provides an engine protection control method and system based on cylinder combustion conditions, based on the basic setting of maintaining the EGR valve opening unchanged after the EGR closed loop enabling condition exits, the initial value of the time length of maintaining the EGR valve opening unchanged is determined, and in the maintaining process, the remaining maintaining time length is optimized based on the occurrence of different levels of knock and the supercharging response, so that the final EGR valve opening maintaining time is obtained, and the improvement of engine knock protection and supercharging control response accuracy is realized.

[0103] It should be noted that according to the needs of implementation, each step / component described in the present application can be split into more steps / components, or two or more steps / components or part of the operation of the steps / components can be combined into new steps / components, so as to realize the purpose of the present application.

[0104] The size of the serial number of each step in the above embodiment does not mean the order of execution, the execution order of each process 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.

[0105] It should be understood that for those skilled in the art, improvements or changes can be made according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. An engine protection control method based on a combustion condition of a cylinder, characterized by, The method comprises the following steps: Periodically sampling the operating parameters of the engine, and determining a pressure ratio coefficient according to the actual pressure at the inlet and outlet of the mixture valve and the actual pressure at the inlet and outlet of the throttle valve when it is determined that the EGR valve no longer meets the EGR closed-loop enabling condition; Determining an initial value of the time length during which the target opening degree of the EGR valve is to be maintained unchanged according to the pressure ratio coefficient and the current engine real-time speed; Updating the remaining time length value during which the target opening degree of the EGR valve is to be maintained unchanged at the current moment according to the change amount of the outlet pressure of the mixture valve, a correction coefficient determined based on the knock frequency, a time length self-learning update coefficient, and the fluctuation of the difference between the target boost pressure and the actual boost pressure; Self-learning updating the time length self-learning coefficient and the supercharger response time self-learning coefficient based on the difference between the updated remaining time length value and the initial remaining time length value, and the change amount of the outlet pressure of the mixture valve; Secondarily self-learning updating the time length self-learning coefficient based on the difference between the updated remaining time length value and the initial remaining time length value, and the knock frequency of different knock intensities; Obtaining the final remaining time length value during which the target opening degree of the EGR valve is to be maintained unchanged according to the secondarily self-learned time length self-learning coefficient.

2. The engine protection control method based on the combustion condition of the cylinder according to claim 1, characterized by, The method for determining the pressure ratio coefficient comprises the following steps: the pressure ratio coefficient is the product of the ratio of the actual outlet pressure of the mixture valve to the actual inlet pressure of the mixture valve and a pressure ratio coefficient correction coefficient, and the pressure ratio coefficient correction coefficient is calibrated under the condition that the ratio of the actual outlet pressure of the throttle valve to the actual inlet pressure of the throttle valve meets a pressure ratio coefficient correction coefficient calibration condition. The pressure ratio coefficient correction coefficient calibration condition comprises the following steps: from the first sampling period when the EGR closed-loop enabling condition is not met to the sampling period corresponding to the end of the initial time length, the fluctuation of the difference between the target boost pressure and the actual boost pressure is within a preset range when the target boost pressure is unchanged.

3. The engine protection control method based on the combustion condition of the cylinder according to claim 2, characterized by, The sampling period corresponding to the initial value of the time length ends is determined by the updated supercharger response time, and the updated supercharger response time τ = τ Boost × (1 + r Boost ), wherein τ Boost is the initial supercharger response time, r Boost is the supercharger response time self-learning coefficient, and the default value is 0. The initial supercharger response time τ Boost The method for obtaining the response time τ includes setting different EGR rates under different engine speeds and different actual intake densities of the cylinder, and obtaining the average value of the supercharger response time by sampling data multiple times.

4. The engine protection control method based on the combustion condition of the cylinder according to claim 3, characterized by, The judgment basis that the fluctuation of the difference between the target boost pressure and the actual boost pressure is within a preset range is that the difference between the target boost pressure and the actual boost pressure is within a preset range when the ratio of the actual outlet pressure of the throttle valve to the actual inlet pressure of the throttle valve meets the pressure ratio coefficient correction coefficient calibration condition. p BoostErrFilter (N) = K BoostErr × [p BoostErr (N) - p BoostErrFilter (N - 1)] + p BoostErrFilter (N - 1) under the premise that the first sampling period in which the EGR closed-loop enabling condition is not met to the sampling period corresponding to the end of the initial value of the time length, all satisfy |p BoostErrFilter (N)-p Boost E rr (N)|<min[p BoostErr (N),p BoostErrFilter (N)]×r BoostErrLim , wherein p BoostErrFilter (N) is a first-order low-pass filtered pressure difference in the Nth sampling period, m is the number of engine cylinders, n is the engine speed, k BoostErr is a preset pressure difference filtering coefficient, p BoostErr (N) is the pressure difference p BoostErr (N-1) in the Nth sampling period, p BoostErrFilter (N-1) is a first-order low-pass filtered pressure difference in the N-1th sampling period, and r BoostErrLim is a preset limit coefficient.

5. The engine protection control method based on the combustion condition of the cylinder according to claim 3, characterized by, The method for obtaining the change amount of the outlet pressure of the mixture valve comprises the following steps: calculating the quotient of the initial supercharger response time and a preset sampling period, and taking the difference between the maximum outlet pressure of the mixture valve and the minimum outlet pressure of the mixture valve in the sampling period corresponding to the quotient value.

6. The engine protection control method based on the combustion condition of the cylinder according to claim 5, characterized by, The method for updating the remaining duration value includes: updating the remaining duration value t1'=t1×(1+k Knock )×[1+f(Δp AfMixAct ,Δp BoostErr )]×(1+r t1 ); wherein k Knock is a correction coefficient based on knock frequency calibration, k Knock =f(r PreRatio , Cnt LowKnock )×f(r PreRatio , Cnt MediumKnock )×f(r PreRatio , Cnt HighKnock ), Cnt LowKnock is a knock frequency of low knock intensity, Cnt MediumKnock is a knock frequency of medium knock intensity, Cnt HighKnock is a knock frequency of high knock intensity, r PreRatio is a compression ratio coefficient, and the calibration basis is that, within a period of time after the updated remaining duration value ends and a preset time is delayed, the fluctuation of the difference between the target boost pressure and the actual boost pressure is within a preset range, and only low-intensity knock below a preset number occurs in the cylinder; Δp AfMixAct is a change amount of the outlet pressure of the mixture valve, Δp BoostErr is a fluctuation of the difference between the target boost pressure and the actual boost pressure, and the calibration basis of f(Δp AfMixAct , Δp BoostErr ) is that the fluctuation of the difference p BoostErr between the target boost pressure and the actual boost pressure is within a preset range; and r t1 is a remaining duration value self-learning coefficient.

7. The engine protection control method based on the combustion condition of the cylinder according to claim 6, characterized by, The method for self-learning updating the time length self-learning coefficient and the supercharger response time self-learning coefficient comprises the following steps: Calculating the difference between the updated remaining time length value and the initial remaining time length value; Determining the state of the current working condition according to the difference between the updated remaining time length value and the initial remaining time length value; the state comprises upward learning state one, upward learning state two, downward learning state one, downward learning state two, and other states; If the current working condition is in the upward learning state, the time length self-learning coefficient is increased; if the current working condition is in the downward learning state, the time length self-learning coefficient is decreased; and if the current working condition is in the other state, the time length self-learning coefficient is not updated.

8. The engine protection control method based on the combustion condition of the cylinder according to claim 7, characterized by, The specific method for determining the state of the current working condition comprises the following steps: If the difference between the updated remaining duration value and the initial remaining duration value is greater than the preset value C1 for more than the preset number of times CNT1, it is determined that the current working condition is in an upward learning state one; if the difference between the updated remaining duration value and the initial remaining duration value is greater than the preset value C1, and the difference between the updated remaining duration value and the initial remaining duration value in the last self-learning process is not greater than the preset value C2, it is determined that the current working condition is in an upward learning state two; If the difference between the updated remaining duration value and the initial remaining duration value is greater than the preset value C2 for more than the preset number of times CNT2, it is determined that the current working condition is in a downward learning state one; if the difference between the updated remaining duration value and the initial remaining duration value is greater than the preset value C2, and the difference between the updated remaining duration value and the initial remaining duration value in the last self-learning process is not greater than the preset value C1, it is determined that the current working condition is in a downward learning state two; The remaining condition is determined as other states.

9. The engine protection control method based on the combustion condition of the cylinder according to claim 8, characterized by, When the current working condition belongs to the upward learning state one, if the number of times that the mixed valve outlet pressure change amount exceeds the preset value A1 exceeds the preset number of times CNT1, the supercharger response time self-learning coefficient is increased by the preset value X1, and it is determined that the current working condition belongs to a sub-upward learning state one; when the current working condition belongs to the downward learning state one, if the number of times that the mixed valve outlet pressure change amount exceeds the preset value A2 exceeds the preset number of times CNT2, the supercharger response time self-learning coefficient is reduced by the preset value X2, and it is determined that the current working condition belongs to a sub-downward learning state one.

10. The engine protection control method based on the combustion condition of the cylinder according to claim 9, characterized by, In each self-learning updating process, if the supercharger response time self-learning coefficient is updated, CNT1 and CNT2 are cleared.

11. The engine protection control method based on the combustion condition of the cylinder according to claim 10, characterized by, The priority of the sub-upward learning state one, the upward learning state one, the sub-downward learning state one, the downward learning state one, the upward learning state two, the downward learning state two, and other working conditions is sequentially reduced, and if it is determined that the current working condition is in a state with high priority, states with low priority are not determined.

12. The engine protection control method based on the combustion condition of the cylinder according to claim 11, characterized by, The method of the secondary self-learning updating comprises: According to the difference between the updated remaining duration value and the initial remaining duration value and the knock number of different knock intensities, the state of the current working condition is determined. The state comprises an upward high knock learning state one, an upward medium knock learning state one, an upward low knock learning state one, an upward knock learning state one, a downward high knock learning state one, a downward medium knock learning state one, a downward low knock learning state one, a downward knock learning state one, and other states. If the current working condition is in an upward learning state, the remaining duration value self-learning coefficient is increased; if the current working condition is in a downward learning state, the remaining duration value self-learning coefficient is reduced; and if the current working condition is in other states, the remaining duration value self-learning coefficient is not updated.

13. The engine protection control method based on the combustion condition of the cylinder according to claim 12, characterized by, The method of determining the state of the current working condition comprises: If the number of knockings of high knock intensity exceeds the preset value A3 by more than the preset number CNT3, the self-learning coefficient of the remaining duration value is increased by the preset value X3, and it is determined that the current working condition is in the upward high knock learning state I; if the number of knockings of medium knock intensity exceeds the preset value A4 by more than the preset number CNT4, the self-learning coefficient of the remaining duration value is increased by the preset value X4, and it is determined that the current working condition is in the upward medium knock learning state I; if the number of knockings of low knock intensity exceeds the preset value A5 by more than the preset number CNT5, the self-learning coefficient of the remaining duration value is increased by the preset value X5, and it is determined that the current working condition is in the upward low knock learning state I; if the number of times that the difference between the updated remaining duration value and the initial remaining duration value is greater than the preset value C1 exceeds the preset number CNT6, the self-learning coefficient of the remaining duration value is increased by the preset value X6, and it is determined that the current working condition is in the upward knock learning state I. In the current working condition, if the number of knock times of high knock intensity exceeds the preset value A6 by more than the preset number CNT7, the remaining duration value self-learning coefficient is reduced by a preset value X7, and it is judged that the current working condition is in a downward high knock learning state I; if the number of knock times of medium knock intensity exceeds the preset value A7 by more than the preset number CNT8, the remaining duration value self-learning coefficient is reduced by a preset value X8, and it is judged that the current working condition is in a downward medium knock learning state I; if the number of knock times of low knock intensity exceeds the preset value A8 by more than the preset number CNT9, the remaining duration value self-learning coefficient is reduced by a preset value X9, and it is judged that the current working condition is in a downward low knock learning state I; if the number of times that the difference between the updated remaining duration value and the initial remaining duration value is not greater than the preset value C2 exceeds the preset number CNT 10 , the remaining duration value self-learning coefficient is reduced by a preset value X 10 , and it is judged that the current working condition is in a downward knock learning state I; In other cases, the self-learning coefficient of the remaining duration value is not updated.

14. The engine protection control method based on the combustion state of the cylinder according to claim 13, characterized by, In each self-learning update process, if the remaining time length value self-learning coefficient is updated, CNT3, CNT4, CNT5, CNT6, CNT7, CNT8, CNT9, CNT 10 Clear.

15. The engine protection control method based on the combustion condition of the cylinder according to claim 14, characterized by, The priority of the upward high knock learning state I, the upward medium knock learning state I, the upward low knock learning state I, the upward knock learning state I, the downward high knock learning state I, the downward medium knock learning state I, the downward low knock learning state I, the downward knock learning state I, and other states decreases in turn, and if it is determined that the current working condition is in a state with high priority, the states with low priority are not determined.

16. An engine protection control system based on cylinder combustion conditions, characterized by, The system performs the engine protection control method based on the cylinder combustion condition according to any one of claims 1-15.

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