A VVT target phase determination method, device and storage medium

Abstract

The present invention discloses a VVT target phase determination method, comprising the following steps: determining a target phase correction parameter X according to engine speed, engine gas path torque, oil pressure and its change rate, engine cooling water temperature, and atmospheric pressure; judging whether the activation condition of the VVT ​​target phase correction is met according to the target phase correction parameter X, the current oil temperature, and the engine running time, and if the activation condition is met, proceeding to the next step; judging whether the first working condition or the second working condition is met according to the current engine operating condition, and if so, correcting the VVT ​​target phase based on the oil temperature; otherwise, limiting the change rate of the VVT ​​target phase. The present invention also discloses a VVT target phase determination device and a storage medium. The present invention avoids the situation where the VVT ​​closed-loop control is disordered due to factors such as dynamic requirements and operating conditions through the VVT ​​target phase correction method, and improves the accuracy and response rate of the closed-loop control.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine control, and more specifically, relates to a VVT target phase determination method, device and storage medium. Background Art

[0002] With the development of the automobile industry and people's increasing attention to the living environment, the requirements for engine power performance, fuel consumption and emissions are getting higher and higher. Studies have shown that VVT (Variable Valve Timing) technology has great advantages in terms of fuel consumption and power. VVT technology uses the deviation between the target phase and the actual phase as a feedback signal for closed-loop control. By adjusting the cam phase, the intake (exhaust) volume and the valve opening and closing time and angle are adjusted to optimize the amount of air entering the engine, so as to improve the combustion efficiency of the engine fuel, increase the engine power, and save fuel consumption. Therefore, VVT technology has been used more and more widely, and has changed from being a unique engine technology to a standard configuration for fuel engines. In order to meet the increasingly stringent emission standards and high requirements for engine thermal efficiency in modern society, engine design is becoming more and more complex, and the engine operating conditions are changing rapidly, resulting in higher and higher control requirements for VVT phase. VVT phase control is to control the actual phase according to the VVT ​​target phase so that the actual phase follows the target phase. When the target phase is affected by the operating conditions and fluctuates, the accuracy of VVT phase control will also be affected. Therefore, how to identify different operating conditions and optimize the target phase of VVT in real time has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to provide a VVT target phase determination method, identify different operating conditions, and optimize the target phase of VVT in real time, so as to fully utilize the advantages of VVT to achieve low fuel consumption and good power requirements.

[0004] To achieve the above object, according to one aspect of the present invention, a method for determining a VVT target phase is provided, comprising the following steps:

[0005] S100: determining a target phase correction parameter X according to the engine speed, the engine gas path torque, the engine oil pressure and its change rate, the engine cooling water temperature, and the atmospheric pressure;

[0006] S200: judging whether the activation condition of the VVT ​​target phase correction is met according to the target phase correction parameter X, the current oil temperature, and the engine running time, and if the activation condition is met, proceeding to the next step;

[0007] S300: judging whether the first operating condition or the second operating condition is satisfied according to the current engine operating condition, and if satisfied, executing S400; otherwise, executing S500;

[0008] S400: Correcting the VVT ​​target phase based on the oil temperature;

[0009] S500: Limiting the rate of change of the VVT ​​target phase.

[0010] Furthermore, the target phase correction parameter X in S100 is determined according to the following formula:

[0011]

[0012] Where n is the engine speed, M Re qAirTrq is the engine request gas circuit torque, M ActAirTrq is the actual gas path torque of the engine, M AirTrqMax is the maximum gas path torque of the engine, p Oil is the oil pressure, Δp Oil is the oil pressure change rate, T Coolant is the engine cooling water temperature, p Amb is atmospheric pressure.

[0013] Furthermore, the activation conditions of the VVT ​​target phase correction in S200 include:

[0014] The target phase correction parameter X is greater than the preset value X1;

[0015] Current oil temperature T Oil Less than the preset value T1;

[0016] The engine running time is not less than the preset time.

[0017] Furthermore, the first working condition in S300 includes:

[0018] The absolute value of the difference between the current original target VVT phase and the actual VVT phase exceeds the preset value Δphi1;

[0019] and the difference between the maximum oil temperature of this driving cycle and the maximum oil temperature during the previous t1 period exceeds the preset temperature ΔT1;

[0020] And the difference between the maximum oil temperature in the previous t1 time and the current oil temperature exceeds the preset temperature ΔT1.

[0021] Furthermore, if the current engine operating condition satisfies the first operating condition, the corrected target VVT phase is:

[0022]

[0023] in, is the original target VVT phase, is the actual VVT phase, is the VVT ​​target phase corresponding to the minimum oil temperature during the first t1 period, is the VVT ​​target phase corresponding to the maximum oil temperature during the period before t1, and k1 and k2 are correction coefficients.

[0024] Furthermore, the second working condition in S300 includes:

[0025] The absolute value of the difference between the current actual VVT phase and the original target VVT phase exceeds the preset value Δphi2;

[0026] The difference between the minimum oil temperature in the previous t1 period and the minimum oil temperature in this driving cycle exceeds the preset temperature ΔT2;

[0027] And the difference between the current engine oil temperature and the minimum engine oil temperature during the previous t1 time exceeds the preset temperature ΔT2.

[0028] Furthermore, if the current engine operating condition satisfies the second operating condition, the corrected target VVT phase is:

[0029]

[0030] in, is the original target VVT phase, is the actual VVT phase, is the VVT ​​target phase corresponding to the minimum oil temperature during the first t1 period, is the VVT ​​target phase corresponding to the maximum oil temperature during the period before t1, and k3 and k4 are correction coefficients.

[0031] Furthermore, limiting the change rate of the VVT ​​target phase in S500 includes: controlling the change rate of the target VVT phase to ±10° / s.

[0032] According to another aspect of the present invention, a VVT target phase determination device is provided, comprising a memory and a processor, wherein a control program is stored in the memory, and the control program is loaded and executed by the processor to implement the VVT ​​target phase determination method as described above.

[0033] According to a third aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a control program, and when the control program is executed by a processor, the control program is used to implement the VVT ​​target phase determination method as described above.

[0034] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0035] The present invention avoids the situation where VVT ​​closed-loop control is disturbed due to factors such as dynamic demand and working conditions by setting a VVT target phase correction method, improves the closed-loop control accuracy and closed-loop control response rate, and thus improves the closed-loop control stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is a flowchart of a method for determining a VVT target phase according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The camshaft phase control system is mainly composed of a cam phaser, a camshaft position sensor, a water temperature sensor, a camshaft timing hydraulic control valve (OCV), a crankshaft position sensor and an electronic control unit (ECU). The cam phaser is mainly composed of a rotor blade, a stator and a return spring. The rotor blade is fixed on the intake camshaft, and the stator is integrated with the driven timing sprocket. The electronic control unit (ECU) calculates the required valve timing angle under various engine working conditions, that is, the target phase; and calculates the actual phase of the camshaft based on the feedback signals from the crankshaft position sensor and the cam position sensor, and then compares the target phase with the actual phase, and sends a control signal to the timing hydraulic control valve based on the deviation between the target phase and the actual phase. When the oil in the system oil circuit is controlled by the timing hydraulic control valve to generate pressure, the oil squeezes the rotor and drives the intake camshaft to rotate, so that the camshaft phase is advanced, delayed or maintained, thereby changing the opening and closing time of the intake valve. During the movement of the rotor, the phaser forms two hydraulic chambers: the valve timing advance chamber and the valve timing delay chamber. In addition, an oil pressure sensor and / or a variable displacement oil pump may be added to the camshaft phase control system, wherein the oil pressure sensor reads the oil pressure of the main oil gallery, and the variable displacement oil pump may adjust the oil pressure.

[0039] The present invention corrects the VVT ​​target phase during engine operation so as to update the VVT ​​target phase in real time, thereby fully utilizing the advantages of VVT.

[0040] like Figure 1 As shown, the present invention provides a method for determining a VVT target phase, comprising the following steps:

[0041] Step 1: Introduce the target phase correction parameter X, and determine the value of X according to the engine speed, engine gas path torque, oil pressure and its change rate, engine cooling water temperature, and atmospheric pressure.

[0042] The purpose of introducing the target phase correction parameter X is to find through experimental research that improving the VVT ​​target phase can increase the engine's gas volume torque and improve power.

[0043] The value of X is determined by the following formula:

[0044]

[0045] Where n is the engine speed, M Re qAirTrq is the engine request gas circuit torque, M ActAirTrq is the actual gas path torque of the engine, M AirTrqMax is the maximum gas path torque of the engine, p Oil is the oil pressure, Δp Oil is the oil pressure change rate, T Coolant is the engine cooling water temperature, p Amb is atmospheric pressure.

[0046] First, determine the parameters This parameter is calculated based on the ratio of the engine speed n, the difference between the engine requested gas path torque and the actual gas path torque, and the engine's maximum gas path torque. The lower the engine speed (the worse the combustion stability), or the greater the difference between the engine's requested gas path torque and the actual gas path torque, The larger the final target phase correction parameter X is, the higher the torque stability requirement is, and the more optimized VVT control is needed. and The corresponding relationship is shown in Table 1.

[0047] Table 1n and and Correspondence table

[0048]

[0049] Secondly, determine the parameter f(p Oil ,Δp Oil ), this parameter is based on the oil pressure p Oil and oil pressure change rate Δp Oil The smaller the oil pressure (the slower the VVT ​​response), or the smaller the oil pressure change rate (the lower the VVT ​​response accuracy), f(p Oil ,Δp Oil ) is larger, the final target phase correction parameter X is also larger, the torque stability requirement is higher, and the more optimized VVT control is needed.Oil and oil pressure change rate Δp Oil and f(p Oil ,Δp Oil ) is shown in Table 2.

[0050] Table 2 Oil pressure p Oil and oil pressure change rate Δp Oil and f(p Oil ,Δp Oil )

[0051]

[0052] Finally, determine the parameter f(T Coolant ,p Amb ), this parameter is based on the engine cooling water temperature T Coolant and atmospheric pressure p Amb The lower the engine cooling water temperature (the poorer the engine thermal combustion stability, the relatively poorer the oil performance, and the slower the VVT ​​action response), or the lower the atmospheric pressure (the thinner the air, the poorer the intake system control stability, and the lower the VVT ​​action response accuracy as an important part of the intake system), f(T Coolant ,p Amb ) is larger, the final target phase correction parameter X is also larger, the torque stability requirement is higher, and the more optimized VVT control is needed. Engine cooling water temperature T Coolant and atmospheric pressure p Amb and f(T Coolant ,p Amb ) is shown in Table 3.

[0053] Table 3T coolant and p Amb and f(T Coolant ,p Amb )

[0054]

[0055] Step 2: Determine whether the activation condition of the VVT ​​target phase correction is met based on the target phase correction parameter X, the oil temperature, and the engine running time. If so, proceed to the next step.

[0056] The activation conditions for VVT target phase correction include:

[0057] 1. The target phase correction parameter X is greater than a preset value X1. In this embodiment, the preset value X1 is 0.5;

[0058] 2. Current oil temperature T Oil Less than a preset value T1, in this embodiment, the preset value T1 is -10°C;

[0059] 3. The engine running time is not less than the preset time to ensure stable engine combustion. In this embodiment, the preset time is 60s.

[0060] The poor performance of the engine oil affects the operation of the engine, so the design goal of the present invention is that the low-temperature engine combustion stability COV IMEP does not exceed 3%.

[0061] The target phase correction process can only be entered when all activation conditions are met.

[0062] Step 3: Determine whether the first operating condition or the second operating condition is met according to the current engine operating condition. If so, correct the VVT ​​target phase based on the oil temperature; otherwise, limit the rate of change of the VVT ​​target phase.

[0063] In order to better calculate and correct the VVT ​​target phase, the present invention proposes 5 types of oil temperatures and groups them. These 5 oil temperatures include: the minimum oil temperature of this driving cycle, the minimum oil temperature within the previous t1 period, the maximum oil temperature within the previous t1 period, the current oil temperature, and the maximum oil temperature of this driving cycle. In this embodiment, t1 is 2s. The meanings of these 5 oil temperatures are:

[0064] The minimum oil temperature T of this driving cycle OilMin : The minimum oil temperature read in the current vehicle driving cycle;

[0065] Minimum oil temperature T before t1 OilMinBeforet1 : The minimum oil temperature at the current time and within the period t1 before (including the time t1 and the current time);

[0066] The maximum oil temperature T within the first t1 period OilMaxBeforet1 : The maximum oil temperature at the current time and within the time t1 before (including the time t1 and the current time);

[0067] Current oil temperature T Oil : Current real-time actual oil temperature;

[0068] The maximum oil temperature T of this driving cycle OilMax : The maximum oil temperature read during the current vehicle driving cycle.

[0069] Read the VVT ​​target phase at the corresponding time of the above 5 oil temperatures:

[0070] 1) The minimum oil temperature T of this driving cycle OilMin , the corresponding VVT target phase is

[0071] 2) Minimum oil temperature T during the first t1 period OilMinBeforet1, the corresponding VVT target phase is

[0072] 3) Maximum oil temperature T within the first t1 period OilMaxBeforet1 , the corresponding VVT target phase is

[0073] 4) Current oil temperature T Oil , the corresponding VVT target phase is

[0074] 5) Maximum oil temperature T of this driving cycle OilMax , the corresponding VVT target phase is

[0075] Whether the first operating condition or the second operating condition is met is determined according to the current operating condition of the engine. If the current operating condition of the engine meets the first operating condition or the second operating condition, the VVT ​​target phase is corrected based on the oil temperature.

[0076] The first working condition includes:

[0077] 1) Current original target VVT phase The actual VVT phase The absolute value of the difference exceeds the preset value Δphi1. In this embodiment, the preset value Δphi1 is 5°;

[0078] 2) And the maximum oil temperature of this driving cycle is T OilMax The maximum oil temperature T during the first t1 period OilMaxBeforet1 The difference exceeds the preset temperature ΔT1. In this embodiment, the preset temperature ΔT1 is 5.5°C.

[0079] 3) and the maximum oil temperature T during the first t1 period OilMaxBeforet1 With the current oil temperature T Oil The difference exceeds the preset temperature ΔT1. In this embodiment, the preset temperature ΔT1 is 5.5°C.

[0080] When the engine is in the first operating condition, it indicates that the current oil temperature is at risk of decreasing during the entire driving cycle. The decrease in oil temperature may increase the oil viscosity and increase the resistance of VVT action. In order to improve the response accuracy of VVT dynamic closed-loop control, VVT target phase dynamic optimization is required.

[0081] At this time, the corrected VVT target phase is:

[0082] Where k1 and k2 are correction coefficients. In this embodiment, k1 is 0.05 and k2 is 0.002. The calibration method of k1 and k2 is: after correction, the target VVT phase phi can be achieved within the preset time t2 (in this embodiment, t2 is 0.5s). Dsrd and actual VVT phase The difference does not exceed the preset value. In this embodiment, the target VVT phase phi Dsrd and actual VVT phase The preset value of the difference is ±1°, and the NVH of the observed VVT execution solenoid valve action is within the subjective evaluation requirements. This adjustment will reduce the difference between the target VVT phase and the actual VVT phase, thereby adjusting the VVT ​​control actuator. The actuator needs oil to push, and the noise and vibration will be improved when the difference is reduced.

[0083] The second working condition includes:

[0084] 1) Current actual VVT phase VVT phase with original target The absolute value of the difference exceeds the preset value Δphi2. In this embodiment, the preset value Δphi2 is 5°;

[0085] 2) and the minimum oil temperature T in the first t1 time OilMinBeforet1 The minimum oil temperature T of this driving cycle OilMin The difference exceeds the preset temperature ΔT2. In this embodiment, the preset temperature ΔT2 is 5.5°C.

[0086] 3) and the current oil temperature T Oil The minimum oil temperature T in the previous t1 period OilMinBeforet1 The difference exceeds the preset temperature ΔT2. In this embodiment, the preset temperature ΔT2 is 5.5°C.

[0087] When the engine is in the second operating condition, it means that the current oil temperature is at risk of increasing in the entire driving cycle. The increase in oil temperature may cause the oil viscosity to decrease, reducing the resistance of VVT action. In order to improve the response accuracy of VVT dynamic closed-loop control, VVT target phase dynamic optimization is required. At this time, the VVT ​​target phase can be appropriately increased.

[0088] At this time, the corrected VVT target phase is:

[0089]

[0090] Where k3 and k4 are correction coefficients. In this embodiment, k3 is 0.02 and k4 is 0.0005. The calibration method of k3 and k4 is as follows: after correction, the target VVT phase phi can be achieved within the preset time t2 (in this example, t2 is 0.5s). Dsrdand actual VVT phase The difference does not exceed the preset value. In this embodiment, the target VVT phase phi Dsrd and actual VVT phase The preset value of the difference is ±1°, and the NVH of the observed VVT execution solenoid valve action is within the subjective evaluation requirements. After such adjustment, the difference between the target VVT phase and the actual VVT phase will be reduced, thereby adjusting the VVT ​​control actuator. The actuator needs oil to push, and the noise and vibration will be improved when the difference is reduced.

[0091] When the activation conditions for VVT target phase correction are met, but the current engine operating condition does not satisfy the first operating condition nor the second operating condition, only the change rate of the VVT ​​target phase is limited, and the change rate of the VVT ​​target phase is controlled within ±10° / s.

[0092] The present invention also provides a VVT target phase determination device, including a memory and a processor, wherein a control program is stored in the memory, and the control program is loaded and executed by the processor to implement the VVT ​​target phase determination method as described above. The processor can be a CPU, a controller, a microcontroller, a microprocessor, or other data processing chips.

[0093] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a control program, and when the control program is executed by a processor, it is used to implement the VVT ​​target phase determination method as described above. The technical solution of the present invention, in essence or in other words, the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each method embodiment of the present invention. The computer-readable storage medium includes various media that can carry computer program codes, such as a USB flash drive, a mobile hard disk, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), and the like.

[0094] In this patent, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0095] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining a VVT target phase, characterized in that: The following steps are involved: S100: determining a target phase correction parameter X according to the engine speed, the engine gas path torque, the engine oil pressure and its change rate, the engine cooling water temperature, and the atmospheric pressure; S200: judging whether the activation condition of the VVT ​​target phase correction is met according to the target phase correction parameter X, the current oil temperature, and the engine running time, and if the activation condition is met, proceeding to the next step; S300: judging whether the first operating condition or the second operating condition is satisfied according to the current engine operating condition, and if satisfied, executing S400; Otherwise, execute S500; The first working condition includes: The absolute value of the difference between the current original target VVT phase and the actual VVT phase exceeds the preset value Δphi1; and the difference between the maximum oil temperature of this driving cycle and the maximum oil temperature during the previous t1 period exceeds the preset temperature ΔT1; and the difference between the maximum oil temperature in the previous t1 time and the current oil temperature exceeds the preset temperature ΔT1; The second working condition includes: The absolute value of the difference between the current actual VVT phase and the original target VVT phase exceeds the preset value Δphi2; The difference between the minimum oil temperature in the previous t1 period and the minimum oil temperature in this driving cycle exceeds the preset temperature ΔT2; and the difference between the current engine oil temperature and the minimum engine oil temperature during the previous t1 period exceeds a preset temperature ΔT2; S400: Correcting the VVT ​​target phase based on the oil temperature; S500: Limiting the change rate of the VVT ​​target phase.

2. The VVT ​​target phase determination method according to claim 1, characterized in that: The target phase correction parameter X in S100 is determined according to the following formula: Where n is the engine speed, M ReqAirTrq is the engine request gas circuit torque, M ActAirTrq is the actual gas path torque of the engine, M AirTrqMax is the maximum gas path torque of the engine, P Oil is the oil pressure, Δp Oil is the oil pressure change rate, T Coolant is the engine cooling water temperature, P Amb is atmospheric pressure.

3. The VVT ​​target phase determination method according to claim 1, characterized in that: The activation conditions of the VVT ​​target phase correction in S200 include: The target phase correction parameter X is greater than the preset value X1; Current oil temperature T Oil Less than the preset value T1; The engine running time is not less than the preset time.

4. The VVT ​​target phase determination method according to claim 1, characterized in that: If the current engine operating condition meets the first operating condition, the corrected target VVT phase is: in, is the original target VVT phase, is the actual VVT phase, is the VVT ​​target phase corresponding to the minimum oil temperature during the first t1 period, is the VVT ​​target phase corresponding to the maximum oil temperature during the period before t1, and k1 and k2 are correction coefficients.

5. The VVT ​​target phase determination method according to claim 1, characterized in that: If the current engine operating condition meets the second operating condition, the corrected target VVT phase is: in, is the original target VVT phase, is the actual VVT phase, is the VVT ​​target phase corresponding to the minimum oil temperature during the first t1 period, is the VVT ​​target phase corresponding to the maximum oil temperature during the period before t1, and k3 and k4 are correction coefficients.

6. The VVT ​​target phase determination method according to claim 1, characterized in that: The limiting the change rate of the VVT ​​target phase in S500 includes: controlling the change rate of the target VVT phase to be within ±10° / s.

7. A VVT target phase determination device, characterized in that: It comprises a memory and a processor, wherein a control program is stored in the memory, and the control program is loaded and executed by the processor to implement the VVT ​​target phase determination method according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a control program, and when the control program is executed by a processor, it is used to implement the VVT ​​target phase determination method according to any one of claims 1 to 6.

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