Method for controlling clutch torque

Abstract

The present invention provides a method for controlling the clutch torque, which is used to control the clutch torque in the closed-loop speed control stage during the starting process of a dual-clutch transmission system. The method includes: determining the speed apex of the engine according to the speed parameter of the engine and the preset speed apex confirmation time; determining the deviation value between the target torque of the clutch and the actual torque of the engine according to the actual torque of the engine and the target torque of the clutch; performing feedforward control on the target torque of the clutch according to the deviation value, and adjusting the actual torque of the clutch according to the target torque of the clutch. The feedforward control process is repeated until a preset condition is met. This solution can enable the torque and speed of the engine to quickly match the torque of the clutch without significant fluctuations, improving the smoothness of the dual-clutch transmission during the starting process.

Description

Technical Field

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

[0002] A dual-clutch transmission is a complex system that involves the combined action of mechanical, electrical, and hydraulic systems. For a vehicle equipped with a dual-clutch transmission, during the starting process, it is necessary to calculate the precise clutch control torque in real time so that the torque of the clutch can be synchronized with the engine speed.

[0003] When the engine speed reaches its peak, the engine speed acceleration is 0 and the inertial torque is 0. At this time, the clutch torque can just transmit the current engine torque. However, at this time, there is a large gap between the final target torque of the clutch and the actual torque of the engine. If the clutch is pressurized according to the target torque of the clutch, it will cause the engine speed to drop. This will cause obvious jerks during the starting process of the vehicle due to the engine speed fluctuation. Even with the intervention of PID regulation, the problem of engine speed fluctuation cannot be avoided.

[0004] Therefore, in the starting process of the existing dual-clutch transmission, clutch torque adaptive control is required to improve its control stability. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of poor smoothness in the starting process of the dual-clutch transmission in the prior art.

[0006] To solve the above problems, an embodiment of the present invention discloses a method for controlling the torque of a clutch, which is used to control the torque of the clutch during the closed-loop speed control stage in the starting process of a dual-clutch transmission system; the dual-clutch transmission system includes an engine, a transmission, and a clutch, and the clutch is arranged between the engine and the transmission; and the method for controlling the torque of the clutch includes the following steps:

[0007] S1: Obtain the engine speed parameters during the closed-loop speed control stage, and determine the engine speed peak according to the engine speed parameters and the preset engine speed peak confirmation time;

[0008] S2: Obtain the actual torque of the engine and the target torque of the clutch corresponding to the engine speed peak, and determine the deviation value between the target torque of the clutch and the actual torque of the engine according to the actual torque of the engine and the target torque of the clutch;

[0009] S3: Perform feedforward control on the target torque of the clutch according to the deviation value, and adjust the actual torque of the clutch according to the target torque of the clutch;

[0010] S4: Repeat steps S1 to S3 until a preset condition is met.

[0011] With the above solution, the deviation value of the feedforward control is determined using the target torque of the clutch and the actual torque of the engine, and the target torque of the clutch in the next feedforward control process is continuously adjusted using this deviation value, enabling the torque and speed of the engine to quickly match the torque of the clutch without significant fluctuations, thereby improving the smoothness of the dual-clutch transmission during the starting process.

[0012] According to another specific embodiment of the present invention, for the clutch torque control method disclosed in the embodiments of the present invention, the engine speed parameter includes the actual speed of the engine; and step S1 includes:

[0013] S11: Obtain the maximum value of the actual speed of the engine.

[0014] S12: Determine whether the actual speed of the engine is the maximum value of the actual speed and the duration is greater than or equal to the speed peak confirmation time.

[0015] If so, use the actual speed of the engine at the moment before the speed peak confirmation time as the speed peak of the engine.

[0016] If not, continue to execute step S11.

[0017] With the above solution, by using the actual speed of the engine at the moment before the speed peak confirmation time as the speed peak of the engine in this way, the determined speed peak of the engine will not be affected by the change rate of the engine speed. Thus, the determined speed peak of the engine is more accurate.

[0018] According to another specific embodiment of the present invention, for the clutch torque control method disclosed in the embodiments of the present invention, before step S1, it further includes: obtaining the torque parameter of the clutch, the torque parameter of the engine, the starting parameter of the engine, and determining whether the torque parameter of the clutch, the torque parameter of the engine, and the starting parameter of the engine all meet the preset speed peak determination conditions;

[0019] If so, execute step S1;

[0020] If not, continue to determine whether the torque parameter of the clutch, the torque parameter of the engine, and the starting parameter of the engine all meet the preset speed peak determination conditions.

[0021] With the above solution, by setting the speed peak determination conditions, storing the preset speed peak determination conditions, and directly obtaining the maximum engine speed when the conditions are met, the opportunity to obtain the speed peak will not be missed, and the efficiency of torque adjustment can be improved.

[0022] According to another specific embodiment of the present invention, for the clutch torque control method disclosed in the embodiments of the present invention, the torque parameters of the clutch include the target torque of the clutch; the torque parameters of the engine include the target torque of the engine and the actual torque of the engine; the starting parameters of the engine include the starting time of the engine; and the preset rotational speed peak determination conditions include: the target torque of the clutch monotonically increases or has a change rate of 0 within a period of time; the range of the difference between the actual torque of the engine and the target torque of the engine is from 0 to 10%; the target torque of the engine is greater than a preset torque threshold, where the range of the preset torque threshold is from 50 N·M to 60 N·M; the starting time of the engine is greater than 100 seconds; and the above conditions need to be satisfied simultaneously.

[0023] With the above solution, when determining the rotational speed peak of the engine, the influences of the starting time of the engine, the target torque of the clutch, the target torque of the engine, the actual torque of the engine, etc. are comprehensively considered, making the determined rotational speed peak more accurate.

[0024] According to another specific embodiment of the present invention, for the clutch torque control method disclosed in the embodiments of the present invention, the dual-clutch transmission system further includes a control device; and step S2 includes:

[0025] S21: Obtain the operating cycle of the control device of the dual-clutch transmission system;

[0026] S22: According to the operating cycle of the control device and the rotational speed peak confirmation time, determine multiple sets of the actual torque of the engine and the target torque of the clutch within a preset time period in a first-in, first-out manner; where

[0027] the duration of the preset time period is greater than or equal to the duration of the rotational speed peak confirmation time, and the end point of the preset time period is the same as the end point of the rotational speed peak confirmation time;

[0028] S23: Use the difference between the actual torque of the engine and the target torque of the clutch corresponding to the moment immediately before the rotational speed peak confirmation time as the deviation value.

[0029] With the above solution, when determining the deviation value, the operating cycle of the control device is considered, avoiding the problem that the data of the rotational speed peak of the engine is not stored in the control device and the rotational speed peak cannot be determined. And according to the operating cycle of the control device and the rotational speed peak confirmation time, multiple sets of the actual torque of the engine and the target torque of the clutch within a preset time period are determined, without storing a large amount of data in the control device, improving the operation efficiency.

[0030] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiments of the present invention, step S23 further includes: obtaining the oil temperature flowing through the clutch, and determining a deviation confirmation time according to the oil temperature and the rotation speed peak confirmation time; obtaining the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time, and taking the difference between the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time as the deviation value.

[0031] With the above solution, by delaying a certain time on the basis of the rotation speed peak confirmation time according to the oil temperature, the deviation confirmation time is obtained, and the difference between the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time is the amount of torque mismatch between the clutch and the engine, which improves the accuracy of the determined deviation value.

[0032] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiments of the present invention, step S3 further includes:

[0033] S3’: Obtaining the control parameters of the engine, and performing feedback control on the target torque of the clutch according to the control parameters and the rotation speed parameters of the engine; wherein, the control parameters of the engine include the target rotation speed of the engine and the target torque of the engine.

[0034] With the above solution, adding feedback control while performing feedforward control can enable the target torque of the clutch to quickly reach the control target.

[0035] According to another specific embodiment of the present invention, in the clutch torque control method disclosed in the embodiments of the present invention, the rotation speed parameters of the engine include the actual rotation speed of the engine; the control parameters of the engine further include the moment of inertia of the engine and the change rate of the target rotation speed of the engine; and the target torque of the clutch is adjusted according to the following formula:

[0036]

[0037] wherein, T c is the final 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 change rate of the target rotation speed of the engine, ω e is the actual rotation speed of the engine, ω t is the target rotation speed of the engine, PID(ω t ,ω e ) is the PID control result regarding the actual rotation speed of the engine and the target rotation speed of the engine, and AdaOfst is the deviation value.

[0038] According to another specific embodiment of the present invention, the method for controlling the clutch torque disclosed in the embodiment of the present invention, step S4 includes: repeating steps S1 to S3, and classifying and storing the deviation values of each feedforward control according to the oil temperature flowing through the clutch and the actual torque of the engine; determining the deviation value of the current feedforward control according to the current oil temperature flowing through the clutch and the actual torque of the engine, and performing feedforward control on the target torque of the clutch in the next feedforward control process according to the deviation value of the current feedforward control until a preset condition is met.

[0039] With the above solution, when the vehicle starts again, the deviation values corresponding to different oil temperatures and clutch torques can be directly called, improving the efficiency of torque adjustment.

[0040] According to another specific embodiment of the present invention, the method for controlling the clutch torque disclosed in the embodiment of the present invention, the preset range of the rotational speed peak confirmation time is 50 milliseconds to 60 milliseconds; and, the preset condition includes: the deviation between the target torque of the engine and the actual torque of the engine is small.

[0041] The beneficial effects of the present invention are:

[0042] This solution uses the target torque of the clutch and the actual torque of the engine to determine the deviation value of the feedforward control, and uses this deviation value to continuously adjust the target torque of the clutch obtained in the next feedforward control process, which can make the torque and rotational speed of the engine quickly match the torque of the clutch without significant fluctuations, improving the smoothness of the dual-clutch transmission during the starting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flowchart of the method for controlling the clutch torque provided by the embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the connection structure of the dual-clutch transmission system in the method for controlling the clutch torque provided by the embodiment of the present invention;

[0045] Figure 3 is a parameter curve graph of the starting process of the dual-clutch transmission system in the method for controlling the clutch torque provided by the embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of the rotational speed peak of the engine in the method for controlling the clutch torque provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The following specific embodiments illustrate the implementation manners of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives 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, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0048] It should be noted that in this specification, similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0049] In the description of this embodiment, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0050] The terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0051] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific situations.

[0052] To make the purpose, technical solutions, and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below with reference to the drawings.

[0053] To solve the problem of poor smoothness of a dual-clutch transmission during the starting process in the prior art, an embodiment of the present invention provides a method for controlling the clutch torque. This method for controlling the clutch torque is used to control the clutch torque during the closed-loop speed control stage of a dual-clutch transmission system during the starting process. Specifically, referring to Figure 1 , the method for controlling the clutch torque provided in this embodiment includes the following steps:

[0054] S1: Obtain the rotational speed parameter of the engine during the closed-loop speed control stage, and determine the rotational speed peak of the engine according to the rotational speed parameter of the engine and the preset rotational speed peak confirmation time;

[0055] S2: Obtain the actual torque of the engine and the target torque of the clutch corresponding to the rotational speed peak of the engine, and determine the deviation value between the target torque of the clutch and the actual torque of the engine according to the actual torque of the engine and the target torque of the clutch;

[0056] S3: Perform feedforward control on the target torque of the clutch according to the deviation value, and adjust the actual torque of the clutch according to the target torque of the clutch;

[0057] S4: Repeat steps S1 to S3 until a preset condition is met.

[0058] By adopting the above solution, the deviation value of the feedforward control is determined by using the target torque of the clutch and the actual torque of the engine, and the target torque of the clutch obtained in the next feedforward control process is continuously adjusted by using this deviation value, which can make the torque and rotational speed of the engine quickly match the torque of the clutch without significant fluctuations, and improve the smoothness of the dual-clutch transmission during the starting process.

[0059] Next, referring to Figures 1-4 the method for controlling the clutch torque provided in this embodiment will be described.

[0060] Before describing the specific steps involved in the method for controlling the clutch torque, the dual-clutch transmission system will be described first. Referring to Figure 2 , the dual-clutch transmission system includes an engine, a transmission, and a clutch. The clutch is arranged between the engine and the transmission. The clutch can cut off or connect the torque transmission between the engine and the transmission. The dual-clutch transmission system in this embodiment has no essential difference from the dual-clutch transmission system in the prior art, and will not be elaborated in this embodiment.

[0061] It should be noted that the method for controlling the clutch torque provided in this embodiment is used to control the clutch torque during the closed-loop speed control stage of the dual-clutch transmission system during the starting process. Referring to Figure 3 ,Figure 3 A parameter curve graph showing the starting process of a dual - clutch transmission system is presented. The Figure 3 contains five curves. Curve 3 - 1 represents the actual engine speed; Curve 3 - 2 represents the input shaft speed of the clutch; Curve 3 - 3 represents the actual engine torque; Figures 3-4 represents the target torque of the clutch; Curve 3 - 5 represents the actual torque of the clutch. Among them, Curves 3 - 1 and 3 - 2 represent speeds, and the unit of the ordinate is revolutions per minute. Curves 3 - 3, 3 - 4, and 3 - 5 all represent torques, and the unit of the ordinate is Newton - meters. The starting process of the dual - clutch transmission system is mainly divided into four stages.

[0062] The first stage, that is, Figure 3 the open - loop control stage (Lash) in . In this stage, the torque of the clutch transitions to the target torque of the engine in an open - loop control manner.

[0063] The second stage, that is, Figure 3 the closed - loop speed control stage (Synchro) in . When the engine speed is close to the target output shaft speed of the clutch, it enters the closed - loop speed control stage.

[0064] The third stage, that is, Figure 3 the smooth control stage (Smooth) in . When the engine speed is close to the target shaft speed of the clutch, it enters Smooth control, and the dual - clutch transmission smoothly engages the clutch.

[0065] The fourth stage, that is, Figure 3 the recovery stage (Reinst) in . In this stage, the clutch is fully engaged, and the vehicle exits the low - speed control.

[0066] The following are the specific steps of the control method for the clutch torque.

[0067] First, execute step S1 to obtain the engine speed parameter within the closed - loop speed control stage, and determine the engine speed peak according to the engine speed parameter and the preset speed peak confirmation time.

[0068] It should be noted that the engine speed parameter includes the actual engine speed. The actual engine speed can be measured in real - time by a speed sensor.

[0069] Specifically, step S1 includes the following steps:

[0070] S11: Obtain the maximum value of the actual engine speed;

[0071] S12: Determine whether the actual engine speed is the maximum value of the actual speed and the duration is greater than or equal to the speed peak confirmation time;

[0072] If so, use the actual engine speed at the moment immediately before the engine speed peak confirmation time as the engine speed peak;

[0073] If not, continue to execute step S11.

[0074] That is to say, in this embodiment, referring to Figure 4 , the engine speed sensor measures the actual engine speed in real time and sends the relevant information of the actual engine speed to the control device (Transmission Control Unit, TCU) of the dual-clutch transmission system. The control device compares the engine speed at the current moment with the engine speed at the previous moment in real time and finds the maximum engine speed, that is, the maximum value of the actual engine speed. After that, the control device continues to receive the relevant information of the actual engine speed. If the engine speed remains at the maximum value of the actual engine speed for a certain period of time, it means that the engine speed value before this period of time is the engine speed peak.

[0075] Specifically, in this embodiment, the preset range of the engine speed peak confirmation time is from 50 milliseconds to 60 milliseconds.

[0076] It should be noted that since the change rate of the engine speed changes violently during the starting process of the engine, in this embodiment, the actual engine speed at the moment immediately before the engine speed peak confirmation time is used as the engine speed peak. In this way, the determined engine speed peak will not be affected by the change rate of the engine speed. Therefore, the determined engine speed peak is more accurate.

[0077] Of course, those skilled in the art can also choose other methods to determine the engine speed peak. For example, when the acceleration of the engine speed is not greater than a certain acceleration value, or Figure 3 the slope of curve 3-1 in

[0078] is not greater than a certain slope value, it means that the engine speed peak has been reached.

[0079] Preferably, in this embodiment, before step S1, it further includes: obtaining the torque parameter of the clutch, the torque parameter of the engine, and the starting parameter of the engine, and determining whether the torque parameter of the clutch, the torque parameter of the engine, and the starting parameter of the engine all meet the preset engine speed peak determination conditions;

[0080] If so, execute step S1;

[0081] That is to say, during the starting process of the engine, the engine speed fluctuates. When determining the peak engine speed, there may be a problem that in order to obtain a maximum speed value, the control device continuously obtains the engine speed data for a long time, and misses the peak engine speed when the engine speed drops. Therefore, in this embodiment, a peak speed determination condition is set to quickly and accurately determine the peak speed. By storing the preset peak speed determination condition in the control device, the control device directly obtains the maximum engine speed when the condition is met, without missing the opportunity to obtain the peak speed, which can improve the efficiency of torque adjustment.

[0082] Specifically, the torque parameter of the clutch includes the target torque of the clutch; the torque parameters of the engine include the target torque of the engine and the actual torque of the engine; the starting parameter of the engine includes the starting time of the engine.

[0083] Among them, the target torque of the clutch can be calculated by a formula. The specific calculation formula is as follows:

[0084]

[0085] Among them, T c is the final 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 change rate of the target engine speed, ω e is the actual engine speed, ω t is the target engine speed, PID(ω t , ω e ) is the PID control result regarding the target engine speed and the actual engine speed.

[0086] PID control, that is, proportional-integral-derivative control, can refer to the prior art and will not be elaborated in this embodiment.

[0087] It should be noted that the above calculation formula of the clutch target torque is the final target torque of the clutch during the current feedback adjustment process, but there is a certain torque difference between the real-time target torque of the clutch and the torque of the engine. The present invention is precisely proposed based on eliminating the above torque difference. The method for determining the torque difference will be described in the following content.

[0088] The target torque of the engine is the target torque that the engine needs to reach during operation, and can be obtained through real-time communication with the engine controller such as CAN, which will not be elaborated in this embodiment.

[0089] The actual torque of the engine and the starting time of the engine can both be obtained through CAN communication.

[0090] More specifically, the preset rotational speed peak determination conditions include: the target torque of the clutch monotonically increases or has a change rate of 0 within a period of time; the range of the difference between the actual torque of the engine and the target torque of the engine is 0 to 10%; the target torque of the engine is greater than the preset torque threshold; the engine startup time is greater than 100 seconds.

[0091] It should be noted that the range of the preset torque threshold is 50 N·M to 60 N·M; and the above conditions need to be satisfied simultaneously.

[0092] Next, step S2 is executed to obtain the actual torque of the engine and the target torque of the clutch corresponding to the rotational speed peak of the engine, and determine the deviation value between the target torque of the clutch and the actual torque of the engine based on the actual torque of the engine and the target torque of the clutch.

[0093] Specifically, step S2 includes:

[0094] S21: Obtain the operating cycle of the control device of the dual-clutch transmission system;

[0095] S22: Determine multiple sets of actual torques of the engine and target torques of the clutch within a preset time period in a first-in, first-out manner according to the operating cycle of the control device and the rotational speed peak confirmation time; where

[0096] the duration of the preset time period is greater than or equal to the duration of the rotational speed peak confirmation time, and the end point of the preset time period is the same as the end point of the rotational speed peak confirmation time;

[0097] S23: Use the difference between the actual torque of the engine and the target torque of the clutch corresponding to the moment before the rotational speed peak confirmation time as the deviation value.

[0098] In this embodiment, the operating cycle of the control device can refer to product manuals, etc.

[0099] Taking the operating cycle of the control device as 10 milliseconds and the rotational speed peak confirmation time as 50 milliseconds as an example for illustration. Since it takes 5 cycles of the control device to reach the duration of one rotational speed peak confirmation time. In this solution, the timing of the rotational speed peak of the engine confirmed by the control device is used to calculate the rotational speed peak confirmation time backward, and the rotational speed of the engine before the rotational speed peak confirmation time is taken as the rotational speed peak. If the operating cycle of the control device is small and the data collected in the previous several operating cycles is not stored in the control device, then when the control device confirms the rotational speed peak of the engine and calculates the rotational speed peak confirmation time backward, the data of the rotational speed peak of the engine is not stored in the control device. Therefore, it is necessary to store multiple sets of actual torques of the engine and target torques of the clutch in the control device according to the operating cycle of the control device and the rotational speed peak confirmation time. And generally, not many sets of data are stored in the control device, otherwise, problems such as large storage capacity and slow operation will occur. In this embodiment, the data is stored in the control device in a first-in-first-out manner.

[0100] Further, step S23 further includes: obtaining the oil temperature of the oil flowing through the clutch, and determining a deviation confirmation time according to the oil temperature and the rotational speed peak confirmation time; obtaining the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time, and taking the difference between the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time as the deviation value.

[0101] It should be noted that the oil temperature can be measured in real time by a temperature sensor.

[0102] Since the actual torque transmitted by the clutch is affected by the oil temperature of the clutch, the lower the oil temperature, the more delayed the torque characteristics of the clutch will be. In order to improve the accuracy of the determined deviation value, in this embodiment, a certain time delay is added to the rotational speed peak confirmation time according to the oil temperature to obtain the deviation confirmation time. The difference between the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time is the amount of torque mismatch between the clutch and the engine.

[0103] After that, step S3 is executed to perform feedforward control on the target torque of the clutch according to the deviation value, and adjust the actual torque of the clutch according to the target torque of the clutch.

[0104] It should be noted that step S3 further includes the following steps:

[0105] S3’: Obtain the control parameters of the engine, and perform feedback control on the target torque of the clutch according to the control parameters and the rotational speed parameters of the engine.

[0106] That is to say, in order to enable the target torque of the clutch to quickly reach the control target, feedback control is also performed on the target torque of the clutch in this embodiment. The specific process of the feedback control can refer to the method of performing feedback control on the target torque of the clutch in the prior art, and will not be elaborated in this embodiment.

[0107] It should be noted that in this embodiment, the control parameters of the engine include the target speed of the engine and the target torque of the engine. The speed parameters of the engine include the actual speed of the engine; the control parameters of the engine also include the moment of inertia of the engine and the change rate of the target speed of the engine.

[0108] Among them, the determination methods of the target speed of the engine, the target torque of the engine, and the actual speed of the engine have been described in the foregoing content and will not be repeated here.

[0109] The moment of inertia of the engine can be obtained by measurement and calculation, and specifically can refer to the method of determining the moment of inertia of the engine in the prior art. The change rate of the target speed of the engine can be calculated based on the target speed of the engine.

[0110] It should also be noted that in this embodiment, the target torque of the clutch is adjusted according to the following formula:

[0111]

[0112] where T c is the final 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 change rate of the target speed of the engine, ω e is the actual speed of the engine, ω t is the target speed of the engine, PID(ω t ,ω e ) is the PID control result regarding the target speed of the engine, the actual speed of the engine, and the target speed of the engine, and AdaOfst is the deviation value.

[0113] After that, step S4 is executed, and steps S1 to S3 are repeated until the preset conditions are met.

[0114] Specifically, step S4 includes: repeating steps S1 to S3, and classifying and storing the deviation values of each feedforward control according to the oil temperature flowing through the clutch and the actual torque of the engine; determining the deviation value of the current feedforward control according to the current oil temperature flowing through the clutch and the actual torque of the engine, and performing feedforward control on the target torque of the clutch in the next feedforward control process according to the deviation value of the current feedforward control until the actual torque of the clutch meets the preset conditions.

[0115] That is to say, in this embodiment, in order to quickly call the deviation values corresponding to different oil temperatures and the actual torque of the engine for feedforward adjustment when the vehicle starts next time, the deviation values obtained by each feedforward adjustment can be stored in an Electrically Erasable Programmable Read-Only Memory (EEPROM), and when starting next time, directly call the deviation values corresponding to different oil temperatures and clutch torques, which improves the efficiency of torque adjustment.

[0116] It should be noted that the preset conditions include that the difference between the target torque of the engine and the actual torque of the engine is less than or equal to a preset value. Among them, those skilled in the art can set the size of the preset value according to actual needs, and the numerical value is not specifically limited in this embodiment.

[0117] In another specific embodiment of the present invention, the control method of the clutch torque includes the following content.

[0118] First, confirm the speed peak of the engine. The method for confirming the speed peak of the engine is not unique. It can be confirmed by the acceleration value of the engine speed not being greater than a certain value, or by the maximum value of the engine speed remaining unchanged for a certain period of time. Because the change rate of the engine speed changes violently, the maximum value method is relatively stable. Specifically, the control device (TCU) calculates the maximum value of the actual engine speed in real time. If the maximum value of the engine speed does not change and lasts for a period of time (speed peak confirmation time), then the actual engine speed before the speed peak confirmation time is considered as the speed peak of the engine. In order to avoid finding the wrong speed peak of the engine, the following conditions should be met when finding the speed peak of the engine: the target torque of the clutch must be in a monotonically increasing or non-decreasing process; the difference between the actual torque and the target torque of the engine is small; the target torque of the engine is greater than a certain value; the engine has been started for a certain time and the torque state has been stable.

[0119] Next, an operation for determining the deviation value between the target torque of the clutch and the actual torque of the engine is performed. Specifically, the control device (TCU) stores a set of deviation values of the target torque of the clutch and the actual torque of the engine in a First Input First Output (FIFO) manner for several cycles. Through the torque difference of the FIFO stored by the control device (TCU), that is, the deviation value, the deviation value at the moment before the rotation speed peak confirmation time is the deviation value between the target torque of the clutch and the actual torque of the engine. If the hysteresis characteristic of the actual torque transmission of the clutch is considered, a certain additional delay time can be set according to the oil temperature of the clutch, and the torque difference of the found FIFO is the deviation value of the torque in the current state.

[0120] After that, the adaptive value is stored. Specifically, it can be grouped according to the engine torque magnitude and the clutch oil temperature, and the deviation values under different engine torques and different oil temperatures are stored in the corresponding Electrically Erasable Programmable Read-Only Memory (EEPROM). When starting again next time, the clutch will select appropriate deviation values as feedforward according to different torques and oil temperatures to automatically adapt to the engine torque and improve the starting smoothness.

[0121] After finding the rotation speed peak of the engine in this solution, it is compared with the torque curve of the clutch stored inside the control device, and the shape of the torque curve inside the control device is automatically optimized. The shape of this torque curve is determined by the difference between the actual torque curve of the engine when finding the rotation speed peak of the engine and the torque curve of the clutch stored inside the control device. And when controlling the start next time, the target torque of the adaptive clutch is directly called to achieve the purpose of automatically correcting the torque curve of the clutch inside the control device.

[0122] As Figure 3 shown, curve 3-4 is the final target of curve 3-5. When finding the rotation speed peak of the engine, the gap between curve 3-4 and curve 3-5 is large, indicating that the target torque of the clutch is too deep. If the clutch pressure is continuously increased according to this target, it will cause the engine speed to drop. Even with the cooperation of PID, the final effect will not be very good. Therefore, the adaptive function needs to be activated so that the target torque curve of the clutch, that is, curve 3-4, subtracts the difference between curve 3-4 and curve 3-5 in this torque section, resulting in a step change in this control to prevent the engine speed from dropping. And when starting again next time, the target torque curve of the adaptive clutch will be directly called, and the actual torque of the clutch will be continuously adjusted according to the target torque of the clutch. So that the actual torque of the clutch can better match the actual torque of the engine.

[0123] Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, those of ordinary skill in the art should understand that the above is a further detailed description of the present invention in connection with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited only to these descriptions. Those skilled in the art can make various changes in form and detail, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for controlling the clutch torque, characterized in that, For controlling the clutch torque during the closed-loop speed control stage of a dual-clutch transmission system during the starting process; the dual-clutch transmission system includes an engine, a transmission, and a clutch, and the clutch is disposed between the engine and the transmission; and The method for controlling the clutch torque includes the following steps: S1: Obtain the rotational speed parameter of the engine during the closed-loop speed control stage, and determine the rotational speed peak of the engine according to the rotational speed parameter of the engine and a preset rotational speed peak confirmation time; the rotational speed parameter of the engine includes the actual rotational speed of the engine; and The step S1 includes: S11: Obtain the maximum value of the actual rotational speed of the engine; S12: Determine whether the actual rotational speed of the engine is the maximum value of the actual rotational speed and the duration is greater than or equal to the rotational speed peak confirmation time; If so, use the actual rotational speed of the engine at the moment before the rotational speed peak confirmation time as the rotational speed peak of the engine; If not, continue to execute the step S11; S2: Obtain the actual torque of the engine and the target torque of the clutch corresponding to the rotational speed peak of the engine, and determine the deviation value between the target torque of the clutch and the actual torque of the engine according to the actual torque of the engine and the target torque of the clutch; S3: Perform feedforward control on the target torque of the clutch according to the deviation value, and adjust the actual torque of the clutch according to the target torque of the clutch; S4: Repeat the steps S1 to S3 until a preset condition is met.

2. The control method of the clutch torque according to claim 1, characterized in that, Before the step S1, it further includes: Obtain the torque parameter of the clutch, the torque parameter of the engine, and the start parameter of the engine, and determine whether the torque parameter of the clutch, the torque parameter of the engine, and the start parameter of the engine all meet the preset rotational speed peak determination conditions; If so, execute the step S1; If not, continue to determine whether the torque parameter of the clutch, the torque parameter of the engine, and the start parameter of the engine all meet the preset rotational speed peak determination conditions.

3. The control method of clutch torque according to claim 2, characterized in that, The torque parameter of the clutch includes the target torque of the clutch; The torque parameter of the engine includes the target torque of the engine and the actual torque of the engine; The start parameter of the engine includes the start time of the engine; And The preset rotational speed peak determination conditions include: The target torque of the clutch is monotonically increasing or the change rate is 0 within a period of time; The range of the difference between the actual torque of the engine and the target torque of the engine is 0 to 10%; The target torque of the engine is greater than a preset torque threshold, where the range of the preset torque threshold is 50 N·m to 60 N·m; The start time of the engine is greater than 100 seconds; and The above conditions need to be met simultaneously.

4. The method for controlling the clutch torque according to claim 1, characterized in that, The dual-clutch transmission system further includes a control device; and The step S2 includes: S21: Obtain the operation cycle of the control device of the dual-clutch transmission system; S22: Determine multiple sets of the actual torque of the engine and the target torque of the clutch within a preset time period in a first-in, first-out manner according to the operating cycle of the control device and the rotation speed peak confirmation time; where the duration of the preset time period is greater than or equal to the duration of the rotation speed peak confirmation time, and the end point of the preset time period is the same as the end point of the rotation speed peak confirmation time; S23: Use the difference between the actual torque of the engine and the target torque of the clutch corresponding to the moment immediately before the rotation speed peak confirmation time as the deviation value.

5. The control method of clutch torque according to claim 4, characterized in that, The step S23 further includes: Obtain the oil temperature flowing through the clutch, and determine the deviation confirmation time according to the oil temperature and the rotation speed peak confirmation time; Obtain the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time, and use the difference between the actual torque of the engine and the target torque of the clutch corresponding to the deviation confirmation time as the deviation value.

6. The method for controlling the clutch torque according to claim 1, characterized in that, The step S3 further includes: S3': Obtain the control parameters of the engine, and perform feedback control on the target torque of the clutch according to the control parameters and the rotation speed parameters of the engine; where the control parameters of the engine include the target rotation speed of the engine and the target torque of the engine.

7. The method for controlling the clutch torque according to claim 6, characterized in that, The control parameters of the engine further include the moment of inertia of the engine and the change rate of the target rotation speed of the engine; and Adjust the target torque of the clutch according to the following formula: Among them, T c is the final 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 change rate of the target speed of the engine, ω e is the actual speed of the engine, ω t is the target speed of the engine, PID(ω t , ω e ) is the PID control result of the target speed of the engine with respect to the actual speed of the engine and the target speed of the engine, and AdaOfst is the deviation value.

8. The method for controlling the clutch torque according to claim 1, characterized in that, The step S4 includes: Repeat the steps S1 to S3, and classify and store the deviation values of each feedforward control according to the oil temperature flowing through the clutch and the actual torque of the engine; Determine the deviation value of the current feedforward control according to the current oil temperature flowing through the clutch and the actual torque of the engine, and perform feedforward control on the target torque of the clutch in the next feedforward control process according to the deviation value of the current feedforward control until the preset conditions are met.

9. The method for controlling the clutch torque according to any one of claims 1-8, characterized in that, The preset range of the rotation speed peak confirmation time is 50 milliseconds to 60 milliseconds; And The preset conditions include: The difference between the target torque of the engine and the actual torque of the engine is less than or equal to a preset value.

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