Variable valve control method and device, engine and vehicle

Abstract

The embodiment of the invention discloses a variable valve control method and device, an engine and a vehicle. The variable valve control method comprises the steps that the target air flow, the variable valve opening upper limit and the variable valve opening lower limit under the current working condition are obtained; according to the engine parameters, the variable valve opening upper limit and the variable valve opening lower limit, the variable valve opening upper limit, the variable valve opening lower limit and the inflation efficiency corresponding to the upper and lower limit median are determined; the current actual air flow is determined according to the actual opening degree of the variable valve and the inflation efficiency, and the target opening degree of the variable valve is determined according to the target air flow and the current actual air flow; a current operation scene is obtained, and the dynamic opening upper limit of the variable valve is determined according to the operation scene; and the final opening degree of the variable valve is determined according to the target opening degree and the dynamic opening degree upper limit. According to the technical scheme, the air flow can be adaptively adjusted in different application scenes, and the engine performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine control, and in particular to a variable valve control method, device, engine and vehicle. Background Art

[0002] Variable Valve Timing (VVT) is a technology used in automotive piston engines. VVT adjusts the overlap and timing (partially or completely) of the engine's intake and exhaust systems, reducing fuel consumption and improving efficiency.

[0003] The engine's valve timing has a significant impact on its power, economy, and exhaust pollution. The optimal valve timing should allow the engine to be filled with the most fresh air (combustible mixture) in a very short ventilation time, while minimizing exhaust resistance and residual exhaust gas. When the engine speed changes, the airflow speed and the absolute time of early opening and late closing of the intake and exhaust valves change, so its optimal valve timing angle should also change accordingly. The engine's valve opening and closing are driven by cams, and the early opening and late closing angles of the intake and exhaust valves are fixed. This actually only allows the engine to be in the optimal valve timing within a certain speed range. At very low or very high engine speeds, its valve timing will be in an undesirable state.

[0004] At low engine speeds, a larger-than-ideal valve overlap causes some of the fresh air mixture to be carried away by exhaust gases, increasing fuel consumption and emissions. At high speeds, a smaller-than-ideal valve overlap results in insufficient intake air, limiting the engine's maximum power. To improve engine performance, variable valve timing and valve lift technology has become a key research topic in automotive engine technology. Summary of the Invention

[0005] Embodiments of the present invention provide a variable valve control method, device, engine and vehicle. The variable valve control method accurately calculates the charging efficiency under variable valve configuration conditions, achieves target air flow in different scenarios, and ensures adaptability and reliability.

[0006] According to one aspect of the present invention, a variable valve control method is provided, comprising:

[0007] Obtaining the target air flow, variable valve opening upper limit, and variable valve opening lower limit under the current working conditions;

[0008] Determining the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits according to engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening;

[0009] Determine the current actual air flow rate based on the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve based on the target air flow rate and the current actual air flow rate;

[0010] Obtain the current operating scenario and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario;

[0011] The final opening of the variable valve is determined based on the target opening and the dynamic opening upper limit.

[0012] Optionally, the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening are pre-calibrated to obtain the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening under the current working condition, including:

[0013] The target air flow rate is obtained by checking the first two-dimensional chart based on the speed and the fuel injection amount of each cylinder. There are different two-dimensional charts in different working modes.

[0014] The upper and lower limits of the variable valve closing time are obtained by looking up the table based on the speed and the single-cylinder fuel injection amount, and the upper and lower limits of the variable valve opening are obtained.

[0015] Optionally, when determining the target air flow rate, the following is also included:

[0016] The target air flow is corrected according to the ambient pressure, ambient temperature, water temperature and intake manifold temperature.

[0017] Optionally, determining the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on the engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening includes:

[0018] Set the target opening of the variable valve at the upper and lower limits and the middle position, scan the universal characteristics respectively, and calculate three sets of charging efficiency based on the air flow results: efficiency = f(air flow, speed, intake manifold temperature, intake manifold pressure), and fill in the corresponding charging efficiency chart respectively;

[0019] By checking three charts based on the speed and intake manifold pressure, the upper and lower limits of the variable valve closing angle and the charging efficiency at the middle position are calculated respectively.

[0020] Optionally, the current actual air flow is determined based on the actual variable valve opening and the charging efficiency, including:

[0021] Perform quadratic Lagrange interpolation in three positions according to the current actual variable valve closing angle:

[0022] f(x)=y0×L0(x)+y1×L1(x)+y2×L2(x)

[0023] L0(x)=(x-x1)×(x-x2) / ((x0-x1)×(x0-x2))

[0024] L1(x)=(x-x0)×(x-x2) / ((x1-x0)×(x1-x2))

[0025] L2(x)=(x-x0)×(x-x1) / ((x2-x0)×(x2-x1))

[0026] Where x0, x1 and x2 correspond to the variable valve closing angles, y0, y1 and y2 correspond to the charging efficiency, x is the target closing angle, and f(x) is the charging efficiency corresponding to the target angle.

[0027] The target opening of the variable valve is determined based on the target air flow and the current actual air flow, including:

[0028] Target air flow + target air flow - actual air flow. Based on the current engine speed, intake manifold pressure, and intake manifold temperature, the main charging model is used to calculate the required charging efficiency. In the charging efficiency charts at the upper, middle, and lower angles, quadratic Lagrange interpolation is used, with the charging efficiency chart output as X and the closing angle corresponding to the charging efficiency as Y, to calculate the target variable valve closing angle.

[0029] Optionally, the current operating scenario is obtained, and the upper limit of the dynamic opening of the variable valve is determined according to the operating scenario, including:

[0030] The reference air-fuel ratio is calculated by looking up a second two-dimensional chart based on the speed and single-cylinder fuel injection amount. The current actual air-fuel ratio minus the reference air-fuel ratio is used as the X input, and the throttle pedal opening minus the throttle pedal opening after low-pass filtering is used as the Y input. The calibration chart is consulted and the output is a weight between 0 and 1. The value is interpolated between the upper and lower limits of the variable valve closing time for this operating condition as the dynamic upper limit of the opening;

[0031] Among them, the weights are different in different operating scenarios, including high-speed scenarios, mountainous scenarios, national highway scenarios or urban scenarios.

[0032] Optionally, the final opening of the variable valve is determined based on the target opening and the dynamic opening upper limit, including:

[0033] When the target opening is less than the upper limit of the dynamic opening, the final opening of the variable valve is determined to be the target opening;

[0034] When the target opening is greater than the dynamic opening upper limit, the final opening of the variable valve is determined to be the dynamic opening upper limit.

[0035] According to another aspect of the present invention, a variable valve control device is provided, comprising:

[0036] An acquisition module is used to obtain a target air flow, a variable valve opening upper limit, and a variable valve opening lower limit under current working conditions;

[0037] A charging efficiency determination module is used to determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening;

[0038] a first determining module, configured to determine a current actual air flow rate according to an actual variable valve opening and a charging efficiency, and to determine a target opening of the variable valve according to a target air flow rate and the current actual air flow rate;

[0039] A second determination module is used to obtain a current operating scenario and determine a dynamic opening upper limit of the variable valve according to the operating scenario;

[0040] The control module is used to determine the final opening of the variable valve according to the target opening and the dynamic opening upper limit.

[0041] According to another aspect of the present invention, an engine is provided, comprising a variable valve and the above-mentioned variable valve control device, wherein the variable valve device is configured to execute the above-mentioned variable valve control method.

[0042] According to yet another aspect of the present invention, a vehicle is provided, comprising the above-mentioned engine.

[0043] The technical solution of the present invention determines the target opening of the variable valve by obtaining the target air flow, variable valve opening upper limit, variable valve opening lower limit, engine parameters, and actual variable valve opening under the current working conditions, and corrects the variable valve target opening according to the vehicle operation scenario, so as to achieve adaptive adjustment of the air flow in different application scenarios, ensure the adaptability and reliability of the engine, and improve the engine performance.

[0044] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 A schematic flow chart of a first variable valve control method provided by an embodiment of the present invention;

[0047] Figure 2 A schematic flow chart of a second variable valve control method provided by an embodiment of the present invention;

[0048] Figure 3 A schematic flow chart of a third variable valve control method provided by an embodiment of the present invention;

[0049] Figure 4 A schematic flow chart of a fourth variable valve control method provided by an embodiment of the present invention;

[0050] Figure 5 A schematic flow chart of a fifth variable valve control method provided by an embodiment of the present invention;

[0051] Figure 6 A schematic flow chart of a sixth variable valve control method provided by an embodiment of the present invention;

[0052] Figure 7 A schematic flow chart of a seventh variable valve control method provided by an embodiment of the present invention;

[0053] Figure 8 A connection diagram of a variable valve control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0055] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0056] Figure 1 A flow chart of a first variable valve control method provided by an embodiment of the present invention is provided. Figure 1 , the variable valve control method includes:

[0057] S10: Obtaining a target air flow rate, a variable valve opening upper limit, and a variable valve opening lower limit under a current operating condition.

[0058] Based on the current engine operating conditions, a calibration method can be used to obtain the ideal target air flow. This target air flow is related to environmental factors such as engine speed and single-cylinder fuel injection volume. A pre-calibrated chart can be created to obtain the corresponding target air flow based on the engine operating conditions.

[0059] The upper limit of the variable valve opening and the lower limit of the variable valve opening can also be obtained by calibration. The upper limit of the variable valve opening can be the upper limit of the variable valve closing angle, and the lower limit of the variable valve opening can be the lower limit of the variable valve closing angle.

[0060] S11. Determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening.

[0061] Among them, the charging efficiency corresponding to the variable valve opening can also be obtained through calibration. During calibration, the variable valve is fixed at the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the middle value of the upper and lower limits, and the corresponding charging efficiency is obtained by scanning points with universal characteristics.

[0062] S12: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0063] The current actual variable valve opening can be measured by a sensor. The current actual air flow can be calculated based on the actual variable valve opening and the charging efficiency. It is understood that for cost reasons, the embodiment of the present invention does not directly use an air flow meter, but instead uses calculation to obtain the actual air flow.

[0064] Among them, when the target air flow is greater than the current actual air flow, it means that the air flow needs to be increased at this time, and the target opening of the variable valve needs to be increased, thereby ensuring the power of the engine; when the target air flow is less than the current actual air flow, it means that the air flow needs to be reduced at this time, and the target opening of the variable valve needs to be decreased to avoid increased fuel consumption and emissions.

[0065] S13: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0066] In some operating scenarios, for example, during transient acceleration processing, the required air flow increases rapidly, so the variable valve opening can be further corrected according to the engine operating scenario to improve the engine's combustion efficiency.

[0067] The dynamic opening upper limit may be a correction value of the variable valve opening.

[0068] Among them, the operating scenarios may include highways, mountainous areas, national highways, cities, smoke protection and transient acceleration processing, which can be set according to actual needs.

[0069] S14: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0070] The final opening of the variable valve is determined based on the target opening and the upper limit of the dynamic opening. The final opening of the variable valve can be the most ideal opening state after considering the engine operating conditions and vehicle operation scenarios.

[0071] For example, when correcting the target opening in combination with the operating scenarios, urban scenarios require more maintenance of exhaust temperature, so the target air flow rate is low; transient acceleration processing scenarios require a high target air flow rate; mountainous areas or high-speed heavy loads have higher demands on power, and plateaus and cold areas require more carbon soot protection. Therefore, different charts can be established according to different operating scenarios to ensure adaptive correction of the target opening.

[0072] Specifically, the upper and lower limits of the variable valve opening are first obtained. These limits, combined with engine parameters, yield the corresponding charging efficiency for these values, along with the median value. A sensor is then used to measure the actual variable valve opening. The current actual air flow is then determined based on the actual variable valve opening, the charging efficiency for these values, and the median value. The target opening of the variable valve is then determined based on the actual air flow and the target air flow. Taking into account the vehicle's operating scenario, the dynamic upper limit of the variable valve opening for that scenario is determined. The final opening of the variable valve is then determined based on the dynamic upper limit and the target opening of the variable valve.

[0073] The technical solution of the embodiment of the present invention determines the target opening of the variable valve by obtaining the target air flow, variable valve opening upper limit, variable valve opening lower limit, engine parameters, and actual variable valve opening under the current working conditions, and corrects the variable valve target opening according to the vehicle operation scenario, so as to achieve adaptive adjustment of the air flow in different application scenarios, ensure the adaptability and reliability of the engine, and improve the engine performance.

[0074] Based on the above embodiments, Figure 2 A flow chart of a second variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 2 As shown, the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening are pre-calibrated; the variable valve control method includes:

[0075] S20. Obtain target air flow rate by looking up a first two-dimensional chart based on the rotational speed and the single-cylinder fuel injection amount. There are different two-dimensional charts in different working modes.

[0076] The first two-dimensional graph may be a relationship table of the engine speed, the fuel injection amount per cylinder, and the target air flow rate, and may be pre-calibrated. The target air flow rate may be determined by the engine speed and the fuel injection amount per cylinder.

[0077] The working mode may be a normal mode, a post-processing heating mode, a regeneration mode, etc. The target air flow rate may be corrected according to different working modes to ensure the accuracy of the target air flow rate.

[0078] S21. Obtain upper and lower limits of the variable valve closing time by looking up the table based on the speed and the single-cylinder fuel injection amount, and obtain the upper limit and lower limit of the variable valve opening.

[0079] Among them, the upper and lower limits of the variable valve closing time can be determined by looking up the table of speed and single-cylinder injection amount, and the upper and lower limits of the variable valve opening can be obtained by looking up the table of speed and intake manifold pressure.

[0080] S22. Determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on the engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening.

[0081] S23: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0082] S24: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0083] S25: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0084] The technical solution of the embodiment of the present invention obtains the engine speed and the single-cylinder fuel injection amount, and the target air flow and the upper and lower limits of the variable valve closing time can be obtained by looking up the table, and then the target air flow and the upper and lower limits of the variable valve opening are obtained, thereby ensuring the accuracy and reliability of subsequent calculations.

[0085] Based on the above embodiments, Figure 3 A flow chart of a third variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 3As shown, the variable valve control method includes:

[0086] S30. Obtain target air flow rate by looking up a first two-dimensional chart based on the rotational speed and the single-cylinder fuel injection amount. Different two-dimensional charts are used in different working modes.

[0087] S31. Correct the target air flow rate according to the ambient pressure, ambient temperature, water temperature, and intake manifold temperature.

[0088] Because ambient pressure, temperature, water temperature, and intake manifold temperature can also affect air flow, the target air flow is corrected based on these factors to ensure accuracy. For example, the speed and per-cylinder fuel injection amount are referenced in a first two-dimensional chart, while the ambient pressure is referenced in a second one-dimensional chart. The outputs of these two charts are multiplied and added to the original target value to obtain the corrected target air flow. The second one-dimensional chart can also be pre-calibrated.

[0089] S32. Obtain upper and lower limits of the variable valve closing time by looking up the table based on the speed and the single-cylinder fuel injection amount, and obtain the upper limit and lower limit of the variable valve opening.

[0090] S33. Determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on the engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening.

[0091] S34: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0092] S35: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0093] S36: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0094] The technical solution of the embodiment of the present invention corrects the target air flow by combining the ambient pressure, ambient temperature, water temperature and intake manifold temperature, thereby preventing errors in the final opening of the variable valve and ensuring adaptability and reliability.

[0095] Based on the above embodiments, Figure 4 A flow chart of a fourth variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 4 As shown, the variable valve control method includes:

[0096] S40: Obtain a target air flow rate, a variable valve opening upper limit, and a variable valve opening lower limit under the current operating condition.

[0097] S41. Set the target opening of the variable valve to the upper and lower limits and the middle position, respectively, scan the universal characteristics once, and calculate three sets of charging efficiency based on the air flow results: efficiency = f(air flow, speed, intake manifold temperature, intake manifold pressure). Fill in the corresponding charging efficiency charts respectively.

[0098] The charging efficiency can be obtained by pre-calibrating the variable valve opening to the upper and lower limits and the middle position, respectively, and then scanning the universal characteristic to obtain the air flow corresponding to the upper and lower limits of the variable valve opening and the middle position.

[0099] S42. Calculate the upper and lower limits of the variable valve closing angle and the charging efficiency at the intermediate position by looking up three charts based on the speed and intake manifold pressure.

[0100] Among them, the variable valve opening upper limit, the variable valve opening lower limit and the charging efficiency corresponding to the intermediate position are calculated based on the air flow, combat speed, intake manifold temperature and intake manifold pressure.

[0101] S43: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0102] S44: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0103] S45: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0104] The technical solution of the embodiment of the present invention obtains the air flow corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits, and calculates the inflation efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits according to the function: efficiency = f (air flow, speed, intake manifold temperature, intake manifold pressure), thereby ensuring the accuracy and reliability of the inflation efficiency acquisition.

[0105] Based on the above embodiments, Figure 5 A flow chart of a fifth variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 5 As shown, the variable valve control method includes:

[0106] S50: Obtain the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening under the current working condition.

[0107] S51. Set the target opening of the variable valve to the upper and lower limits and the middle position, respectively, scan the universal characteristics once, and calculate three sets of charging efficiency based on the air flow results: efficiency = f(air flow, speed, intake manifold temperature, intake manifold pressure), and fill in the corresponding charging efficiency charts.

[0108] S52. Calculate the upper and lower limits of the variable valve closing angle and the charging efficiency at the intermediate position by looking up three charts based on the speed and intake manifold pressure.

[0109] S53. Perform a quadratic Lagrangian interpolation at three positions based on the current actual variable valve closing angle:

[0110] f(x)=y0×L0(x)+y1×L1(x)+y2×L2(x)

[0111] L0(x)=(x-x1)×(x-x2) / ((x0-x1)×(x0-x2))

[0112] L1(x)=(x-x0)×(x-x2) / ((x1-x0)×(x1-x2))

[0113] L2(x)=(x-x0)×(x-x1) / ((x2-x0)×(x2-x1)).

[0114] Among them, x0, x1 and x2 correspond to the variable valve closing angle respectively, y0, y1 and y2 correspond to the charging efficiency respectively, x is the target closing angle, and f(x) is the charging efficiency corresponding to the target angle.

[0115] Because the relationship between air flow and variable valve closing angle is nonlinear, a quadratic Lagrangian interpolation algorithm is used to calculate the charging efficiency corresponding to the target angle. Quadratic Lagrangian interpolation is performed on the current actual variable valve closing angle at the upper and lower limits of the variable valve opening, as well as at intermediate positions, to obtain the charging efficiency corresponding to the current actual variable valve closing angle.

[0116] S54: Target air flow + target air flow - actual air flow. Based on the current engine speed, intake manifold pressure, and intake manifold temperature, the main charging model is used to calculate the required charging efficiency. Using the charging efficiency charts at the upper, middle, and lower angles, quadratic Lagrange interpolation is used, with the output of the charging efficiency chart as X and the closing angle corresponding to the charging efficiency as Y, to calculate the target variable valve closing angle.

[0117] Among them, under the conditions of known target air flow and actual air flow, the required charging efficiency is calculated according to efficiency = f (air flow, speed, intake manifold temperature, intake manifold pressure), and the corresponding target variable valve closing angle is calculated based on the required charging efficiency combined with the Lagrange interpolation algorithm, realizing the feedforward and feedback of the target intake valve closing angle.

[0118] S55: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0119] S56: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0120] The technical solution of the embodiment of the present invention obtains the charging efficiency and air flow by calculation under the configuration of the variable valve mechanism, and performs Lagrange interpolation at three points. This method fully considers the nonlinear relationship between the variable valve control amount and the charging efficiency, thereby ensuring the reliability of the calculation results.

[0121] Based on the above embodiments, Figure 6 A flow chart of a sixth variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 6 As shown, the variable valve control method includes:

[0122] S60: Obtain the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening under the current working condition.

[0123] S61. Determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening.

[0124] S62: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0125] S63. Calculate the reference air-fuel ratio by consulting a second two-dimensional chart based on the speed and the single-cylinder fuel injection amount. Use the current actual air-fuel ratio minus the reference air-fuel ratio as the X input and the accelerator pedal opening minus the accelerator pedal opening after low-pass filtering as the Y input. Consult the calibration chart and output a weighted value between 0 and 1. Interpolate between the upper and lower limits of the variable valve closing time for this operating condition to serve as the dynamic upper limit of the opening.

[0126] Among them, the weights are different in different operating scenarios, including high-speed scenarios, mountainous scenarios, national highway scenarios or urban scenarios.

[0127] The dynamic upper limit of the opening is used to adjust the final opening of the variable valve according to the operating scenario. Therefore, it must be considered in conjunction with the air-fuel ratio and the transient nature of driving demand. The reference air-fuel ratio is an air-fuel ratio close to the smoke limit under each operating condition, with a margin for the smoke limit.

[0128] Specifically, a reference air-fuel ratio is calculated from a second two-dimensional chart based on engine speed and per-cylinder fuel injection quantity. The difference between the current actual air-fuel ratio and the reference air-fuel ratio is then calculated. The difference between the accelerator pedal opening and the low-pass filtered accelerator pedal value is then calculated. When the actual air-fuel ratio approaches the reference air-fuel ratio, the valve should close earlier to allow more fresh air to increase the air-fuel ratio. The difference between the accelerator pedal opening and the low-pass filtered accelerator pedal value reflects the degree of engine transients. When the pedal dynamic deviation Y is large, the valve should close earlier to allow more fresh air to improve responsiveness. Weights are determined based on the difference between the current actual air-fuel ratio and the reference air-fuel ratio, as well as the difference between the accelerator pedal opening and the low-pass filtered accelerator pedal value. The dynamic upper limit of the opening is determined by interpolation, combining the upper and lower limits of the variable valve closing time.

[0129] Different operating scenarios have different weights. Urban scenarios require more maintenance of exhaust temperature, so the target air flow is low and the weight is small; transient acceleration processing scenarios require high target air flow and have a large weight; mountainous areas or high-speed heavy loads have higher demands for power, and plateaus and cold areas require more carbon smoke protection. Therefore, different weights can be set according to different operating scenarios to ensure adaptive correction of the target opening.

[0130] S64: Determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0131] The technical solution of the embodiment of the present invention calculates weights based on the deviation between the air-fuel ratio and the reference air-fuel ratio and the carbon soot changes, and then calculates the dynamic limit of the variable valve actuator opening. When a specific operating scenario occurs, the air flow is controlled in time to balance the power and exhaust temperature management.

[0132] Based on the above embodiments, Figure 7 A flow chart of a seventh variable valve control method provided by an embodiment of the present invention is shown as follows: Figure 7 As shown, the variable valve control method includes:

[0133] S70: Obtain the target air flow, the upper limit of the variable valve opening, and the lower limit of the variable valve opening under the current working condition.

[0134] S71. Determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits based on engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening.

[0135] S72: Determine the current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0136] S73: Obtain the current operating scenario, and determine the upper limit of the dynamic opening of the variable valve according to the operating scenario.

[0137] S74: When the target opening is less than the dynamic opening upper limit, determine the final opening of the variable valve as the target opening.

[0138] When the target opening is less than the upper limit of the dynamic opening, it means that the target opening does not exceed the upper limit of the dynamic opening, so the final opening of the variable valve can be regarded as the target opening.

[0139] S75: When the target opening is greater than the upper limit of the dynamic opening, determine the final opening of the variable valve as the upper limit of the dynamic opening.

[0140] Among them, when the target opening is greater than the dynamic opening upper limit, it means that the target opening exceeds the dynamic opening upper limit and there is an operational risk. Therefore, the final opening of the variable valve is set as the dynamic opening upper limit.

[0141] The technical solution of the embodiment of the present invention ensures that the final opening of the variable valve is within the dynamic opening range by comparing the target opening with the dynamic opening upper limit, balances the power and exhaust temperature management, and ensures adaptability and reliability in different application scenarios.

[0142] Based on the same inventive concept, Figure 8 A connection diagram of a variable valve control device provided by an embodiment of the present invention is shown in FIG. Figure 8 As shown, an embodiment of the present invention further provides a variable valve control device, comprising:

[0143] The acquisition module 100 is used to obtain the target air flow, the upper limit of the variable valve opening and the lower limit of the variable valve opening under the current working condition.

[0144] The charging efficiency determination module 200 is used to determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening and the median of the upper and lower limits according to engine parameters, the upper limit of the variable valve opening and the lower limit of the variable valve opening.

[0145] The first determination module 300 is configured to determine a current actual air flow rate according to the actual variable valve opening and the charging efficiency, and to determine a target opening of the variable valve according to the target air flow rate and the current actual air flow rate.

[0146] The second determination module 400 is configured to obtain a current operating scenario and determine a dynamic upper limit of the variable valve opening according to the operating scenario.

[0147] The control module 500 is used to determine the final opening of the variable valve according to the target opening and the upper limit of the dynamic opening.

[0148] Specifically, first, the acquisition module 100 is used to obtain the target air flow, the upper limit of the variable valve opening and the lower limit of the variable valve opening under the current working conditions; then the charging efficiency determination module 200 is used to determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening and the median of the upper and lower limits based on the engine parameters, the upper limit of the variable valve opening and the lower limit of the variable valve opening; then the first determination module 300 is used to determine the current actual air flow based on the actual variable valve opening and the charging efficiency, and determine the target opening of the variable valve based on the target air flow and the current actual air flow; then the second determination module 400 is used to obtain the current operating scenario, and determine the dynamic opening upper limit of the variable valve based on the operating scenario; then the control module 500 is used to determine the final opening of the variable valve based on the target opening and the dynamic opening upper limit.

[0149] The variable valve control device provided by the embodiment of the present invention can be used to execute any of the variable valve control methods provided by the above embodiments, has corresponding functional modules, and has the same technical effects.

[0150] An embodiment of the present invention further provides an engine, comprising the above-mentioned variable valve control device.

[0151] Since the engine provided by the embodiment of the present invention includes the variable valve control device provided by the above embodiment, it has the same or corresponding technical effects as the variable valve control device and will not be described in detail here.

[0152] An embodiment of the present invention further provides a vehicle, comprising the engine provided by the above embodiment.

[0153] Since the vehicle provided by the embodiment of the present invention includes the engine provided by the above embodiment and has the same or corresponding technical effects as the engine, it will not be described in detail here.

[0154] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A variable valve control method, characterized in that: include: Obtaining the target air flow, variable valve opening upper limit, and variable valve opening lower limit under the current working conditions; Determining, based on engine parameters, a variable valve opening upper limit and a variable valve opening lower limit, a charging efficiency corresponding to the variable valve opening upper limit, the variable valve opening lower limit, and a midpoint between the upper and lower limits; determining a current actual air flow rate according to the actual variable valve opening and the charging efficiency, and determining a target opening of the variable valve according to the target air flow rate and the current actual air flow rate; Acquiring a current operating scenario, and determining a dynamic opening upper limit of the variable valve according to the operating scenario; The final opening of the variable valve is determined according to the target opening and the dynamic opening upper limit.

2. The variable valve control method according to claim 1, characterized in that: The target air flow, the variable valve opening upper limit, and the variable valve opening lower limit are pre-calibrated, and the target air flow, the variable valve opening upper limit, and the variable valve opening lower limit under the current working condition are obtained, including: The target air flow rate is obtained by looking up a first two-dimensional chart based on the speed and the single-cylinder fuel injection amount, and different two-dimensional charts are provided in different working modes; The upper and lower limit values of the variable valve closing time are obtained by looking up the table based on the speed and the single-cylinder fuel injection amount, and the upper and lower limit values of the variable valve opening are obtained.

3. The variable valve control method according to claim 2, characterized in that: When determining the target air flow, the method further includes: The target air flow is corrected according to the ambient pressure, ambient temperature, water temperature and intake manifold temperature.

4. The variable valve control method according to claim 1, characterized in that: Determining the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and the median of the upper and lower limits according to engine parameters, including: Set the target opening of the variable valve at the upper and lower limits and the middle position, scan the universal characteristics respectively, and calculate three sets of charging efficiency based on the air flow results: efficiency = f(air flow, speed, intake manifold temperature, intake manifold pressure), and fill in the corresponding charging efficiency chart respectively; By checking three charts based on the speed and intake manifold pressure, the upper and lower limits of the variable valve closing angle and the charging efficiency at the middle position are calculated respectively.

5. The variable valve control method according to claim 4, characterized in that: Determining a current actual air flow rate according to the actual variable valve opening and the charging efficiency includes: Perform quadratic Lagrange interpolation in three positions according to the current actual variable valve closing angle: f(x)=y0×L0(x)+y1×L1(x)+y2×L2(x) L0(x)=(x-x1)×(x-x2) / ((x0-x1)×(x0-x2)) L1(x)=(x-x0)×(x-x2) / ((x1-x0)×(x1-x2)) L2(x)=(x-x0)×(x-x1) / ((x2-x0)×(x2-x1)) Where x0, x1 and x2 correspond to the variable valve closing angles, y0, y1 and y2 correspond to the charging efficiency, x is the target closing angle, and f(x) is the charging efficiency corresponding to the target angle. Determining a target opening of the variable valve according to the target air flow and the current actual air flow includes: Target air flow + target air flow - actual air flow. Based on the current engine speed, intake manifold pressure, and intake manifold temperature, the main charging model is used to calculate the required charging efficiency. In the charging efficiency charts at the upper, middle, and lower angles, quadratic Lagrange interpolation is used, with the charging efficiency chart output as X and the closing angle corresponding to the charging efficiency as Y, to calculate the target variable valve closing angle.

6. The variable valve control method according to claim 1, characterized in that: Acquiring a current operating scenario and determining a dynamic opening upper limit of the variable valve according to the operating scenario, including: The reference air-fuel ratio is calculated by looking up a second two-dimensional chart based on the speed and single-cylinder fuel injection amount. The current actual air-fuel ratio minus the reference air-fuel ratio is used as the X input, and the throttle pedal opening minus the throttle pedal opening after low-pass filtering is used as the Y input. The calibration chart is consulted and the output is a weight between 0 and 1. The value is interpolated between the upper and lower limits of the variable valve closing time for this operating condition as the dynamic upper limit of the opening; Among them, the weights are different in different operating scenarios, and the operating scenarios include high-speed scenarios, mountainous scenarios, national highway scenarios or urban scenarios.

7. The variable valve control method according to claim 1, characterized in that: Determining a final opening of the variable valve according to the target opening and the dynamic opening upper limit includes: When the target opening is less than the dynamic opening upper limit, determining the final opening of the variable valve as the target opening; When the target opening is greater than the dynamic opening upper limit, the final opening of the variable valve is determined to be the dynamic opening upper limit.

8. A variable valve control device, characterized in that: include: An acquisition module is used to obtain a target air flow, a variable valve opening upper limit, and a variable valve opening lower limit under current working conditions; a charging efficiency determination module, configured to determine the charging efficiency corresponding to the upper limit of the variable valve opening, the lower limit of the variable valve opening, and a midpoint between the upper and lower limits based on engine parameters, the upper limit of the variable valve opening, and the lower limit of the variable valve opening; a first determining module, configured to determine a current actual air flow rate according to an actual variable valve opening and the charging efficiency, and determine a target opening of the variable valve according to the target air flow rate and the current actual air flow rate; a second determining module, configured to obtain a current operating scenario and determine a dynamic opening upper limit of the variable valve according to the operating scenario; A control module is used to determine a final opening of the variable valve according to the target opening and the dynamic opening upper limit.

9. An engine, characterized in that: The invention comprises a variable valve and the variable valve control device according to claim 8, wherein the variable valve device is used to execute the variable valve control method according to any one of claims 1 to 7.

10. A vehicle, characterized in that: Including the engine described in claim 9.

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