Control method for clutch torque

Abstract

The present invention provides a clutch torque control method, comprising obtaining an actual engine speed parameter and a final target engine speed parameter during a speed synchronization control phase, and determining a target engine speed curve during the speed synchronization control phase based on the actual speed parameter, the final target speed parameter, and a preset curve variation rule; determining a real-time target engine parameter during the speed synchronization control phase based on the target speed curve; obtaining an operating parameter of the engine during the speed synchronization control phase, and determining a target torque of the clutch based on the operating parameter and the real-time target parameter. Through the above scheme, at the moment when the engine speed synchronizes with the target shaft speed of the clutch, both the acceleration of the engine speed and the acceleration of the target shaft speed of the clutch are synchronized, and the speed difference between the two is also synchronized, thereby improving the smoothness of vehicle starting and shifting.

Description

Technical Field

[0001] The present invention relates to the technical field of dual-clutch automatic transmissions, and in particular to a method for controlling clutch torque. Background Art

[0002] A dual-clutch automatic transmission (DCT) is a complex system that integrates mechanical, electrical, and hydraulic systems. During the inertia phase of starting and shifting, when the engine speed transitions from the initial speed to the final target speed, vehicles equipped with DCTs require precise real-time calculation of clutch control torque to ensure that the clutch torque remains synchronized with the engine speed. A common method for calculating clutch control torque is to calculate the target engine speed and the rate of change of the target engine speed at each moment in real time, then fit these data sets into an ideal real-time target engine speed curve.

[0003] However, current common algorithms can only ensure that the speed difference between the engine speed and the target shaft speed can be completely synchronized within the specified time, and the acceleration of the two cannot be guaranteed to be synchronized, which will still cause uneven starting and shifting processes. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of uneven starting and shifting processes of an automobile in the prior art.

[0005] To address the above-mentioned issues, embodiments of the present invention disclose a clutch torque control method for controlling clutch torque during the speed synchronization control phase of a dual-clutch transmission system during starting and shifting. The dual-clutch transmission system includes an engine, a transmission, and a clutch, with the clutch disposed between the engine and the transmission. The clutch torque control method includes the following steps:

[0006] S1: Acquiring an actual speed parameter of the engine during the speed synchronization control phase and a final target speed parameter of the engine, and determining a target speed curve of the engine during the speed synchronization control phase based on the actual speed parameter, the final target speed parameter, and a preset curve change rule; wherein the actual speed parameter of the engine includes an actual speed change rate of the engine at the starting point of the speed synchronization control phase, and the final target speed parameter of the engine includes a final target speed change rate of the engine;

[0007] S2: determining the real-time target parameters of the engine in the speed synchronization control phase according to the target speed curve;

[0008] S3: Acquire the operating parameters of the engine in the speed synchronization control stage, and determine the target torque of the clutch according to the operating parameters and the real-time target parameters.

[0009] By adopting the above scheme, in the speed synchronization control stage of the dual-clutch transmission system, the final target speed parameter of the engine is used as feedforward, the real-time calculated engine target speed parameter is utilized, and the target torque of the clutch is controlled through closed-loop control, so that the actual speed of the engine smoothly transitions to the final engine target speed according to the target trajectory, and within the specified engine target speed synchronization time, the actual speed of the engine and the real-time target speed can simultaneously meet the speed difference synchronization and speed acceleration synchronization at the end of the time, making the starting and shifting process smoother.

[0010] According to another specific embodiment of the present invention, the clutch torque control method disclosed in the embodiment of the present invention, step S1 includes the following steps:

[0011] S11: acquiring an actual speed parameter of the engine and a final target speed parameter of the engine during the speed synchronization control phase, and determining a real-time target speed parameter of the engine based on the actual speed parameter and the final target speed parameter;

[0012] S12: Determine a target speed curve according to the real-time target speed parameter and a preset curve change rule.

[0013] By adopting the above solution, the target speed curve is determined according to the real-time target speed parameter and the preset curve change rule, which can make the target speed curve more accurate.

[0014] According to another specific embodiment of the present invention, the clutch torque control method disclosed in the embodiment of the present invention, in step S11, the actual speed parameter of the engine also includes the actual speed of the engine at the starting point of the speed synchronization control stage; the final target speed parameter of the engine also includes the final target speed of the engine; the real-time target speed parameter of the engine includes the actual speed at the starting point of the target speed curve, the speed change rate at the starting point of the target speed curve, the actual speed at the end point of the target speed curve, and the speed change rate at the end point of the target speed curve; and, in step S11, the real-time target speed parameter of the engine is determined according to the actual speed parameter and the final target speed parameter, including: determining the actual speed of the engine at the starting point of the speed synchronization control stage as the actual speed of the starting point of the target speed curve; determining the actual speed change rate of the engine at the starting point of the speed synchronization control stage as the speed change rate of the starting point of the target speed curve; determining the final target speed of the engine as the actual speed at the end point of the target speed curve; and determining the final target speed change rate of the engine as the speed change rate at the end point of the target speed curve.

[0015] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiment of the present invention, in step S12, the preset curve change rule is a monotonous change when the target speed curve transitions to the final target speed; and step S12 includes: determining the target speed curve based on the real-time target speed parameter, the preset curve change rule, and using the cubic spline interpolation method.

[0016] By adopting the above solution and using the cubic spline interpolation method to determine the target speed curve, a target speed curve that meets the requirements can be determined quickly and accurately.

[0017] According to another specific embodiment of the present invention, the clutch torque control method disclosed in the embodiment of the present invention uses a cubic spline function method to determine the target speed curve, including:

[0018] S121: determining the starting point of the target speed curve as the function starting point of the cubic spline function, and determining the end point of the target speed curve as the function end point of the cubic spline function;

[0019] S122: Obtaining a function value expression at the function starting point, an acceleration expression at the function starting point, a function value expression at the function end point, and an acceleration expression at the function end point;

[0020] S123: Determine expressions for coefficients in the cubic spline function expression based on the function value expression at the function starting point, the acceleration expression at the function starting point, the function value expression at the function end point, the acceleration expression at the function end point, the time corresponding to the function starting point, the time corresponding to the function end point, and a preset cubic spline function expression;

[0021] S124: simplifying the expressions of the coefficients in the cubic spline function expression according to the ideal condition of the function endpoint;

[0022] S125: Determine the acceleration boundary of the function starting point according to the simplified expressions of the coefficients and the acceleration expression of the cubic spline function;

[0023] S126: Determine a target speed curve according to the acceleration boundary of the function starting point, the real-time target speed parameter, and a preset curve change rule.

[0024] By adopting the above scheme, the expressions of the coefficients in the cubic spline function expression are simplified according to the ideal conditions of the function endpoint, which can simplify certain calculation steps and find the conditions of the fastest monotonically descending cubic spline.

[0025] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiment of the present invention, in step S123, the preset cubic spline function expression is:

[0026] Prof(t)=y(t)=at 3 +bt 2 +ct+d

[0027] Where Prof(t) is the function value, a, b, c, and d are coefficients, and t is time.

[0028] The expressions of each coefficient are:

[0029]

[0030] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 Rate is the acceleration expression of the function end point, Y1 is the function value expression of the function end point, and Y0 is the function value expression of the function starting point.

[0031] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiment of the present invention, in step S124, the ideal conditions for the function endpoint include that the speed of the tangential axis at the function endpoint is constant during the time corresponding to the function endpoint, and the acceleration of the tangential axis at the function endpoint during the time corresponding to the function endpoint is zero; and the expressions of the coefficients after simplified processing are:

[0032]

[0033] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the function starting point, Y1 is the function value expression at the function end point, and Y0 is the function value expression at the function starting point; and in step S125, the acceleration boundary at the function starting point is:

[0034]

[0035] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 is the function value expression at the end point of the function, and Y0 is the function value expression at the starting point of the function.

[0036] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiment of the present invention, the real-time target parameters of the engine include a real-time calculated target rate of change of the engine speed and a real-time calculated target engine speed.

[0037] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiment of the present invention, the operating parameters of the engine in the speed synchronization control stage include the target torque, moment of inertia, and actual speed of the engine; step S3 includes the following steps:

[0038] S31: determining a PID control result regarding the target rate of change of the engine speed calculated in real time and the target speed of the engine calculated in real time based on the target rate of change of the engine speed calculated in real time and the target speed of the engine calculated in real time;

[0039] S32: Determine the target torque of the clutch according to the PID control result and the operating parameters.

[0040] With the above solution, during the calculation of the target torque of the clutch, the target change rate of the engine speed and the PID control result of the target engine speed calculated in real time are taken into account, thereby improving the accuracy of the target torque.

[0041] According to another specific embodiment of the present invention, the clutch torque control method disclosed in the embodiment of the present invention calculates the target torque of the clutch according to the following formula:

[0042]

[0043] Among them, T c is the target torque of the clutch, T e is the target torque of the engine, J e is the engine's moment of inertia, is the target rate of change of engine speed calculated in real time, ω e is the actual engine speed, ω t is the target speed of the engine calculated in real time, PID (ω t ,ω e ) is the PID control result regarding the target rate of change of the engine speed calculated in real time and the target engine speed calculated in real time.

[0044] The beneficial effects of the present invention are:

[0045] The clutch torque control method provided by the present invention first determines the target speed curve of the engine during the speed synchronization control phase based on the actual engine speed parameter, the final target engine speed parameter, and a preset curve change rule; then determines the real-time target parameters of the engine based on the target speed curve; and finally, controls the clutch torque based on the real-time target parameters. In this scheme, the parameters related to the engine's target speed are determined based on the parameters related to the actual speed. When determining the parameters related to the target speed, the influence of the engine's actual speed change rate at the starting point of the speed synchronization control phase and the engine's final target speed change rate are considered, thereby improving the accuracy of the parameters related to the determined engine target speed. Directly determining the real-time target parameters based on the target speed curve eliminates the need to calculate the real-time target parameters, saving calculation steps and improving calculation efficiency. Controlling the clutch torque based on the target parameters can synchronize the acceleration of the engine speed with the clutch's target shaft speed, improving the smoothness of the starting and shifting processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 1 is a flow chart of a method for controlling clutch torque provided by an embodiment of the present invention;

[0047] Figure 2 is a parameter curve diagram of a dual-clutch transmission system during a starting process in a clutch torque control method provided by an embodiment of the present invention;

[0048] Figure 3 is a graph of a cubic spline function in a clutch torque control method provided by an embodiment of the present invention;

[0049] Figure 4 is a graph of a cubic spline function when the initial acceleration values of the cubic spline function are different in the clutch torque control method provided by an embodiment of the present invention;

[0050] Figure 5 is a curve diagram of a simplified cubic spline function in the clutch torque control method provided by an embodiment of the present invention;

[0051] Figure 6 is a graph showing the acceleration of the simplified cubic spline function when the initial acceleration values of the cubic spline function are different in the clutch torque control method provided by an embodiment of the present invention;

[0052] Figure 7 is a graph of an ideal cubic spline function in the clutch torque control method provided by an embodiment of the present invention;

[0053] Figure 8This is a function curve diagram when the axial acceleration of the straight line in the tangential direction of the end point of the cubic spline function in the clutch torque control method provided by an embodiment of the present invention is not zero;

[0054] Figure 9 This is a graph of the acceleration of the function when the axial acceleration of the straight line in the tangent direction of the end point of the cubic spline function in the clutch torque control method provided by an embodiment of the present invention is not zero. DETAILED DESCRIPTION

[0055] The following is an explanation of the embodiments of the present invention by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will contain many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0056] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0057] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0058] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0059] In the description of this embodiment, it should be noted that, unless otherwise specified or limited, the terms "disposed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this embodiment based on specific circumstances.

[0060] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0061] To address the issue of uneven starting and shifting during vehicle starts in the prior art, embodiments of the present invention disclose a clutch torque control method. This clutch torque control method is used to control clutch torque during the speed synchronization control phase of a dual-clutch transmission system during starting and shifting.

[0062] Specifically, refer to Figure 1 The clutch torque control method provided in this embodiment includes the following steps:

[0063] S1: Acquiring an actual speed parameter of the engine during the speed synchronization control phase and a final target speed parameter of the engine, and determining a target speed curve of the engine during the speed synchronization control phase based on the actual speed parameter, the final target speed parameter, and a preset curve change rule; wherein the actual speed parameter of the engine includes an actual speed change rate of the engine at the starting point of the speed synchronization control phase, and the final target speed parameter of the engine includes a final target speed change rate of the engine;

[0064] S2: determining the real-time target parameters of the engine in the speed synchronization control phase according to the target speed curve;

[0065] S3: Acquire the operating parameters of the engine in the speed synchronization control stage, and determine the target torque of the clutch according to the operating parameters and the real-time target parameters.

[0066] Using the above scheme, the target speed curve for the engine during the speed synchronization control phase is first determined based on the actual engine speed parameters, the final target engine speed parameters, and a preset curve variation rule. The real-time target parameters for the engine are then determined based on the target speed curve. Finally, the clutch torque is controlled based on the real-time target parameters. In this scheme, the target speed parameters for the engine are determined based on the actual speed parameters. The determination of the target speed parameters takes into account the influence of the actual speed change rate at the start of the speed synchronization control phase and the final target speed change rate, thereby improving the accuracy of the determined target speed parameters. Directly determining the real-time target parameters based on the target speed curve eliminates the need to calculate the real-time target parameters, saving calculation steps and improving computational efficiency. Incorporating the theoretically calculated real-time target parameters into the calculation of the clutch target torque enables dual synchronization of speed difference and acceleration when the engine speed synchronizes to the clutch target shaft speed within a specified timeframe.

[0067] Specifically, refer to Figure 1-9 The clutch torque control method provided in this embodiment is described.

[0068] Before describing the clutch torque control method provided in this embodiment, the structure of the dual-clutch transmission system must be explained. In this embodiment, the dual-clutch transmission system includes an engine, a transmission, and a clutch, with the clutch positioned between the engine and the transmission. The clutch can interrupt or connect torque transmission between the engine and the transmission. The dual-clutch transmission system in this embodiment is essentially the same as conventional dual-clutch transmission systems and will not be further described in this embodiment.

[0069] It is also necessary to explain the starting process of the dual clutch transmission system. Figure 2 ,Should Figure 2 Contains 6 curves. Curve 2-1 represents the calculated torque of the clutch, curve 2-2 represents the target torque of the engine, curve 2-3 represents the input shaft speed of the clutch, curve 2-4 (dashed line) represents the real-time target speed of the engine, curve 2-5 (solid line) represents the actual speed of the engine, and curve 2-6 represents the final target speed of the engine. Among them, curve 2-1 and curve 2-2 both represent torque, and the unit of their vertical coordinates is Nm. Curves 2-3, 2-4, 2-5, and 2-6 represent speeds, and the unit of their vertical coordinates is revolutions per minute. In addition, the starting process of the dual-clutch transmission system is mainly divided into 4 stages.

[0070] The first stage, that is Figure 2 The open-loop control phase (Lash) in this phase is where the clutch torque transitions to the target engine torque using open-loop control.

[0071] The second stage, Figure 2 When the engine speed approaches the target output shaft speed of the clutch, the speed synchronization control phase begins.

[0072] The third stage, Figure 2 When the engine speed approaches the clutch's target shaft speed, the dual-clutch transmission enters Smooth control, and the clutch engages smoothly.

[0073] The fourth stage, Figure 2 In the recovery phase (Reinst), the clutch is fully engaged and the car exits low-speed control.

[0074] Next, the clutch torque control method provided by this embodiment is described.

[0075] First, execute step S1 to obtain the actual speed parameter of the engine in the speed synchronization control stage and the final target speed parameter of the engine, and determine the target speed curve of the engine in the speed synchronization control stage based on the actual speed parameter, the final target speed parameter, and the preset curve change rule.

[0076] It should be noted that the target speed curve of the engine in the speed synchronization control stage in this embodiment is Figure 2 The real-time target speed curve of the engine is shown in Figure 2-4.

[0077] More specifically, step S1 includes the following steps:

[0078] S11: acquiring an actual speed parameter of the engine and a final target speed parameter of the engine during the speed synchronization control phase, and determining a real-time target speed parameter of the engine based on the actual speed parameter and the final target speed parameter;

[0079] S12: Determine a target speed curve according to the real-time target speed parameter and a preset curve change rule.

[0080] Specifically, the actual engine speed parameter includes the actual engine speed change rate at the start of the speed synchronization control phase, and the final target engine speed parameter includes the final target engine speed change rate. Furthermore, the actual engine speed parameter also includes the actual engine speed at the start of the speed synchronization control phase, and the final target engine speed parameter also includes the final target engine speed.

[0081] The actual engine speed change rate at the start of the speed synchronization control phase refers to the slope of the engine's actual speed curve 2-5 immediately after entering the speed synchronization control phase. The actual engine speed at the start of the speed synchronization control phase refers to the speed value of the engine's actual speed curve 2-5 immediately after entering the speed synchronization control phase.

[0082] The final target speed change rate of the engine refers to the change rate of the final target speed of the engine shown by the curve 2-6. The final target speed of the engine refers to the speed value of the final target speed of the engine shown by the curve 2-6.

[0083] The real-time target speed parameters of the engine include the actual speed at the starting point of the target speed curve, the speed change rate at the starting point of the target speed curve, the actual speed at the end point of the target speed curve, and the speed change rate at the end point of the target speed curve.

[0084] The actual speed at the starting point of the target speed curve is Figure 2 The speed value of the starting point of the real-time target speed curve of the engine shown in curve 2-4 is the speed change rate of the starting point of the target speed curve. Figure 2 The slope of the starting point of the real-time target speed curve of the engine shown in curve 2-4 is the actual speed at the end point of the target speed curve. Figure 2 The speed value of the end point of the real-time target speed curve of the engine shown in curve 2-4 is the speed change rate of the starting point of the target speed curve. Figure 2 Curves 2-4 show the slope of the end point of the real-time target speed curve of the engine.

[0085] That is to say, in this embodiment, in order to make the actual speed of the engine close to the real-time target speed, and to make the engine close to the final target speed of the engine in the later stage of the speed synchronization control stage, the relevant parameters of the real-time target speed 2-4 of the engine will be determined based on the relevant parameters of the actual speed curve 2-5 of the engine and the relevant parameters of the final target speed curve 2-6 of the engine.

[0086] It should be noted that in step S11, the real-time target speed parameter of the engine is determined based on the actual speed parameter and the final target speed parameter, including the following steps: determining the actual speed of the engine at the starting point of the speed synchronization control stage as the actual speed at the starting point of the target speed curve; determining the actual speed change rate of the engine at the starting point of the speed synchronization control stage as the speed change rate of the starting point of the target speed curve; determining the final target speed of the engine as the actual speed at the end point of the target speed curve; and determining the final target speed change rate of the engine as the speed change rate at the end point of the target speed curve.

[0087] That is to say, in this embodiment, in order to make the actual speed of the engine close to the real-time target speed, and to make the engine close to the final target speed of the engine in the later stage of the speed synchronization control stage, it is necessary to set the speed value and slope of curve 2-4 at the starting point of the speed synchronization control stage to values equal to the speed value and slope of curve 2-5 at the starting point of the speed synchronization control stage.

[0088] Furthermore, step S12 includes: determining a target speed curve according to real-time target speed parameters and preset curve variation rules, and using a cubic spline interpolation method.

[0089] It should be noted that, in step S12, the preset curve change rule is that the target speed curve changes monotonically when transitioning to the final target speed.

[0090] That is to say, in order to avoid causing torque fluctuations in the clutch, the real-time target speed curve 2-4 of the entire engine should change monotonically in the direction of the final target speed, and no change in the direction of the rate of change is allowed in the middle.

[0091] It should also be noted that in this embodiment, the process of determining the real-time target speed parameters is also the process of determining the starting and ending points of curves 2-4. Given the starting and ending points, as well as the direction of the curves, this embodiment uses the cubic spline function method to determine an optimal target speed curve that meets the requirements.

[0092] The following combination Figures 3 to 9 How to determine the target speed curve using the cubic spline function method in this embodiment is described.

[0093] Specifically, in this embodiment, determining the target speed curve using the cubic spline function method includes the following steps:

[0094] S121: Determine the starting point of the target speed curve as the function starting point of the cubic spline function, and determine the end point of the target speed curve as the function end point of the cubic spline function.

[0095] Specifically, refer to Figure 3 ,Should Figure 3 In the example, the horizontal axis is time and the vertical axis is acceleration. The goal of this example is to find a smooth curve for the time period from 0 to T1. The figure contains two curves 3-1 and 3-2 and a straight line 3-3. The direction of straight line 3-3 is the tangent direction of point B.

[0096] Curve 3-2 does not meet the requirements because the acceleration is negative in the period from 0 to T1. What we need is a curve like Curve 3-1.

[0097] S122: Obtain the function value expression of the function starting point, the acceleration expression of the function starting point, the function value expression of the function end point, and the acceleration expression of the function end point.

[0098] The above engineering problem can be transformed into a mathematical problem: a smooth curve is required to transition from point A (starting point) to point B (end point). In addition, the following conditions must be met at both points A and B:

[0099] Condition 1: The function value at point A (starting point) is Y0, and the acceleration is Y0_Rate; the specific formula is:

[0100] Prof(0)=Y0

[0101]

[0102] Condition 2: The function value at point B (end point) is Y1, and the acceleration is Y1_Rate; the specific formula is:

[0103] Prof(T1)=Y1

[0104]

[0105] S123: Determine the expressions of the coefficients in the cubic spline function expression based on the function value expression at the function starting point, the acceleration expression at the function starting point, the function value expression at the function end point, the acceleration expression at the function end point, the time corresponding to the function starting point, the time corresponding to the function end point, and the preset cubic spline function expression.

[0106] Specifically, the preset cubic spline function expression is:

[0107] Prof(t)=y(t)=at 3 +bt 2 +ct+d

[0108] Where Prof(t) is the function value, a, b, c, and d are coefficients, and t is time.

[0109] According to the above cubic spline function expression, the following formula can be obtained:

[0110] y(0)=Y0=d

[0111]

[0112] y(T1)=Y1=aT1 3 +bT1 2 +cT1+d

[0113]

[0114] According to the above formula, the expressions of each coefficient can be deduced as follows:

[0115]

[0116] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 Rate is the acceleration expression of the function end point, Y1 is the function value expression of the function end point, and Y0 is the function value expression of the function starting point.

[0117] According to the above formula, when the values of the coefficients are fixed, a cubic curve can be obtained. However, when the acceleration value of the starting point A is different, some cubic curves may not meet the requirements. The curve required in this embodiment should be monotonically decreasing.

[0118] Specifically, refer to Figure 4 .Should Figure 4 In the figure, the horizontal axis represents time and the vertical axis represents speed. Curve 4-1, curve 4-2, and curve 4-3 respectively represent three cubic spline function curves with different initial acceleration values at different starting points, the same time, and the same target. Among them, the absolute value of the initial acceleration value is curve 4-1>curve 4-2>curve 4-3. However, among the three curves, curve 1 is not monotonically decreasing and cannot be used as a function for gear shift control. Curves 4-2 and 4-3 are both monotonically decreasing, but curve 4-2 decreases faster than curve 4-3. Therefore, when the initial acceleration value is too large, no cubic spline function curve meets the requirements.

[0119] S124: Simplifying the expressions of the coefficients in the cubic spline function expression according to the ideal condition of the function endpoint.

[0120] Specifically, the ideal conditions for the end point of the function include that the speed of the tangent axis of the end point of the function is constant during the time corresponding to the end point of the function, and the acceleration of the tangent axis of the end point of the function during the time corresponding to the end point of the function is zero.

[0121] In other words, in order to find the ideal spline curve, simplify certain calculation steps, and find the conditions for the fastest monotonically descending cubic spline, it is necessary to simplify the cubic spline function. Figure 5 , in this Figure 2 The curve 5-1 and the straight line 5-2 are included. The direction of the straight line 5-2 is the tangent direction of the end point B.

[0122] In order to simplify the cubic spline function, it can be assumed that the axis speed of the straight line 5-2 is constant within the time T1 and the acceleration is 0.

[0123] More specifically, the expressions of the coefficients after simplification are:

[0124]

[0125] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 is the function value expression at the end point of the function, and Y0 is the function value expression at the starting point of the function.

[0126] S125: Determine the acceleration boundary of the function starting point based on the simplified expressions of the coefficients and the acceleration expression of the cubic spline function.

[0127] According to the expressions of the coefficients after the simplification process in step S124, when the values of the coefficients are determined, a cubic curve can be obtained. The acceleration curve of the simplified cubic spline function obtained in this embodiment is as follows: Figure 6 As shown. Figure 6 The curve 6-1, the curve 6-2 and the curve 6-3 are included, and the curve 6-1, the curve 6-2 and the curve 6-3 are all acceleration curves.

[0128] In actual control, the acceleration curve should be a parabola. Curve 6-1 has two zero points between 0 and T1, making it non-monotonous. Curve 6-3 has only one zero point, T1, but its acceleration is too high. Therefore, Curve 6-2 is the ideal curve. For Curve 6-2, T1 is the axis of symmetry of the parabola.

[0129] Experiments show that once the absolute value of the initial acceleration exceeds that of Curve 6-2, the shape of Curve 6-1 will appear. Therefore, the initial acceleration value calculated from the axis of symmetry of the acceleration curve is the critical value of acceleration. Using this method, we can find the boundary of the initial acceleration value (the acceleration at the starting point of the function).

[0130] Specifically, the calculation process of the acceleration boundary at the starting point of the function is as follows:

[0131] According to the formula The following formula can be inferred:

[0132]

[0133] Then we can infer that the acceleration boundary of the function starting point is:

[0134]

[0135] Among them, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 is the function value expression at the end point of the function, and Y0 is the function value expression at the starting point of the function.

[0136] According to the above acceleration boundary values, we can draw the following conclusions: As long as the absolute value of the initial acceleration is less than 3 times the slope of the straight line passing through points AB, we can get the following: Figure 7 The shown interpolation function curve is an ideal cubic spline that decreases monotonically and meets the dual requirements of continuity of function values and acceleration at points A and B.

[0137] In this Figure 7 The ideal cubic spline function curve 7-1 is included, and straight lines 7-2 and 7-3 represent the upper and lower limits of the initial acceleration value of curve 7-1, respectively. The direction of straight line 7-4 is the tangential direction of the end point B.

[0138] It should be noted that in the process of obtaining the ideal cubic spline function curve described above, the cubic spline function was simplified to simplify the calculation and obtain the conditions for the fastest monotonically descending cubic spline. During the simplification process, the axial acceleration of the line in the tangential direction of the endpoint B was assumed to be 0, but in reality it is constantly changing. To compensate for the calculation error caused by the simplification process, it is necessary to calculate the change in the axial acceleration of the line in the tangential direction of the endpoint B in real time, ΔOncSpd, and superimpose this calculated ΔOncSpd acceleration value on the cubic spline function curve to solve the problem. The specific calculation method is as follows.

[0139] First, we get the following formula:

[0140]

[0141] According to the above formula, the following formula can be inferred:

[0142]

[0143] refer to Figure 8 and Figure 9 Curve 8-1 is a cubic spline function curve when the axial acceleration of the straight line in the tangential direction of the end point B is not 0, and straight line 8-2 is a straight line in the tangential direction of the end point B of curve 8-1.

[0144] Curve 9-1 is an acceleration curve of a cubic spline function when the axial acceleration of the straight line in the tangential direction of the end point B is not zero, and straight line 9-2 is a straight line in the tangential direction of the end point B of curve 9-1.

[0145] S126: Determine a target speed curve according to the acceleration boundary of the function starting point, the real-time target speed parameter, and a preset curve change rule.

[0146] That is, the curve shape between the start point and the end point of the real-time target speed of the engine can be determined according to step S125 and the steps before it. By combining the start point and the end point of the determined real-time target speed curve of the engine, the target speed curve of the engine (real-time target speed curve) can be determined.

[0147] After the real-time target speed curve is determined, step S2 is executed to determine the real-time target parameters of the engine in the speed synchronization control phase according to the target speed curve.

[0148] Specifically, the real-time target parameters of the engine include a target change rate of the engine speed calculated in real time and a target engine speed calculated in real time.

[0149] That is, the target speed of the engine corresponding to each moment and the corresponding change rate of the target speed (ie, the target speed change rate) need to be determined based on the target speed curve of the engine.

[0150] Thereafter, step S3 is executed to obtain the operating parameters of the engine in the speed synchronization control phase, and determine the target torque of the clutch according to the operating parameters and the real-time target parameters.

[0151] Specifically, the operating parameters of the engine in the speed synchronization control stage include the target torque, moment of inertia, and actual speed of the engine.

[0152] The target torque of the engine is the target torque that the engine needs to achieve when running. The engine's rotational inertia can be obtained by looking up the table, and the actual speed can be obtained by actual measurement.

[0153] More specifically, step S3 includes the following steps:

[0154] S31: determining a PID control result regarding the target rate of change of the engine speed calculated in real time and the target speed of the engine calculated in real time based on the target rate of change of the engine speed calculated in real time and the target speed of the engine calculated in real time;

[0155] S32: Determine the target torque of the clutch according to the PID control result and the operating parameters.

[0156] PID control is a closed-loop feedback control. In this closed-loop control, the real-time calculated target rate of change of the engine speed and the real-time calculated target engine speed are used as inputs. The specific process can be referred to the existing technology and will not be described in detail in this embodiment.

[0157] It should be noted that the target torque of the clutch is calculated according to the following formula:

[0158]

[0159] Among them, T c is the target torque of the clutch, T e is the target torque of the engine, J e is the moment of inertia of the engine, is the target rate of change of engine speed calculated in real time, ω e is the actual speed of the engine, ω t is the target speed of the engine calculated in real time, PID (ω t ,ω e ) is the PID control result regarding the target rate of change of the engine speed calculated in real time and the target engine speed calculated in real time.

[0160] Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the above description is provided as a further detailed description of the present invention in conjunction with specific embodiments thereof, and that the specific implementation of the present invention is not limited to these descriptions. Those skilled in the art may make various changes in form and details, including simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A clutch torque control method, characterized in that: Used to control the clutch torque of a dual-clutch transmission system during the speed synchronization control stage during starting and shifting; the dual-clutch transmission system includes an engine, a transmission, and a clutch, the clutch being arranged between the engine and the transmission; and The clutch torque control method comprises the following steps: S1: Acquire the actual speed parameter of the engine during the speed synchronization control phase and the final target speed parameter of the engine, and determine the target speed curve of the engine during the speed synchronization control phase according to the actual speed parameter, the final target speed parameter, and a preset curve change rule; The actual speed parameter of the engine includes the actual speed change rate of the engine at the starting point of the speed synchronization control stage, and the final target speed parameter of the engine includes the final target speed change rate of the engine; S2: determining a real-time target parameter of the engine in the speed synchronization control stage according to the target speed curve; S3: acquiring operating parameters of the engine in the speed synchronization control stage, and determining the target torque of the clutch according to the operating parameters and the real-time target parameters; The step S1 comprises the following steps: S11: acquiring an actual speed parameter of the engine and a final target speed parameter of the engine during the speed synchronization control phase, and determining a real-time target speed parameter of the engine according to the actual speed parameter and the final target speed parameter; S12: Determine the target speed curve according to the real-time target speed parameter and the preset curve change rule; wherein, In step S11, the actual speed parameter of the engine also includes the actual speed of the engine at the starting point of the speed synchronization control stage; The final target speed parameter of the engine also includes the final target speed of the engine; The real-time target speed parameters of the engine include the actual speed at the starting point of the target speed curve, the speed change rate at the starting point of the target speed curve, the actual speed at the end point of the target speed curve, and the speed change rate at the end point of the target speed curve; and In step S11, determining the real-time target speed parameter of the engine according to the actual speed parameter and the final target speed parameter includes: determining the actual speed of the engine at the starting point of the speed synchronization control stage as the actual speed at the starting point of the target speed curve; determining the actual speed change rate of the engine at the starting point of the speed synchronization control stage as the speed change rate at the starting point of the target speed curve; determining a final target speed of the engine as an actual speed at an end point of the target speed curve; The final target speed change rate of the engine is determined as the speed change rate at the end point of the target speed curve.

2. The clutch torque control method according to claim 1, wherein: In step S12, the preset curve change rule is that the target speed curve changes monotonically when transitioning to the final target speed; and The step S12 includes: The target speed curve is determined according to the real-time target speed parameter and the preset curve change rule and by using a cubic spline interpolation method.

3. The clutch torque control method according to claim 2, wherein: Determining the target speed curve by using the cubic spline function method includes: S121: determining the starting point of the target speed curve as the function starting point of the cubic spline function, and determining the end point of the target speed curve as the function end point of the cubic spline function; S122: Obtaining a function value expression of the function starting point, an acceleration expression of the function starting point, a function value expression of the function end point, and an acceleration expression of the function end point; S123: Determine expressions of coefficients in the cubic spline function expression according to the function value expression at the function starting point, the acceleration expression at the function starting point, the function value expression at the function end point, the acceleration expression at the function end point, the time corresponding to the function starting point, the time corresponding to the function end point, and a preset cubic spline function expression; S124: Simplifying the expressions of the coefficients in the cubic spline function expression according to the ideal condition of the function endpoint; S125: determining the acceleration boundary of the function starting point according to the simplified expressions of the coefficients and the acceleration expression of the cubic spline function; S126: Determine the target speed curve according to the acceleration boundary of the function starting point, the real-time target speed parameter, and the preset curve change rule.

4. The clutch torque control method according to claim 3, wherein: In the step S123, The preset cubic spline function expression is: Prof(t)=y(t)=at 3 +bt 2 +ct+d Where Prof(t) is the function value, a, b, c, and d are coefficients, and t is time. The expressions of each coefficient are: Wherein, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression of the starting point of the function, Y1 Rate is the acceleration expression of the end point of the function, Y1 is the function value expression of the end point of the function, and Y0 is the function value expression of the starting point of the function.

5. The clutch torque control method according to claim 3, wherein: In the step S124, The ideal conditions for the function endpoint include that the velocity of the tangent axis of the function endpoint is constant during the time corresponding to the function endpoint, and the acceleration of the tangent axis of the function endpoint during the time corresponding to the function endpoint is zero; and The expressions of the coefficients after simplification are: Wherein, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression at the starting point of the function, Y1 is the function value expression at the end point of the function, and Y0 is the function value expression at the starting point of the function; and In the step S125, The acceleration boundary at the starting point of the function is: Wherein, T1 is the time corresponding to the end point of the function, Y0 Rate is the acceleration expression of the starting point of the function, Y1 is the function value expression of the end point of the function, and Y0 is the function value expression of the starting point of the function.

6. The clutch torque control method according to any one of claims 1 to 5, characterized in that: The real-time target parameters of the engine include a target change rate of the engine speed calculated in real time and a target engine speed calculated in real time.

7. The clutch torque control method according to claim 6, wherein: The operating parameters of the engine in the speed synchronization control stage include the target torque, moment of inertia, and actual speed of the engine; The step S3 comprises the following steps: S31: determining a PID control result regarding the target change rate of the engine speed calculated in real time and the target speed of the engine calculated in real time according to the target change rate of the engine speed calculated in real time and the target speed of the engine calculated in real time; S32: Determine the target torque of the clutch according to the PID control result and the operating parameters.

8. The clutch torque control method according to claim 7, wherein: The target torque of the clutch is calculated according to the following formula: Among them, T c is the target torque of the clutch, T e is the target torque of the engine, J e is the moment of inertia of the engine, is the target rate of change of the engine speed calculated in real time, ω e is the actual speed of the engine, ω t is the target speed of the engine calculated in real time, PID (ω t ,ω e ) is the PID control result regarding the target change rate of the engine speed calculated in real time and the target speed of the engine calculated in real time.

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