A tip-out torque control method for a dual clutch transmission during a launch process

Abstract

The application discloses a kind of double clutch transmission starting process Tipout torque control method, receives and processes input signal;According to input signal calculation Tipout control activation condition, including: throttle opening signal, clutch starting state, TCS control state, engine real torque;S3, enter Tipout control and start timing, detect the control duration under Tipout state;S4, according to the difference between engine target speed and idle speed calculation clutch feedforward torque;S5, whether the control duration under Tipout state is greater than set threshold is judged;S6, calculate clutch coupling torque recovery slope.The application very good solves the engine throttle etc. "hysteresis" factor causes when throttle is loose, engine torque continues to rise, clutch torque coupling quantity increases and causes vehicle impact, improves NVH and driving comfort.

Description

Technical Field

[0001] This invention relates to the field of dual-clutch automatic transmissions for automobiles, and more specifically to a Tipout torque control method for the start-up process of a dual-clutch transmission. Background Technology

[0002] The DCT transmission uses two clutches, each corresponding to one of the two input shafts. Power transmission is continuously delivered through the engagement of the offgoing and oncoming clutches. The DCT not only inherits the advantages of traditional manual transmissions, such as high transmission efficiency, compact structure, and low cost, but also offers uninterrupted power delivery and smooth, rapid gear shifts during driving. Its key features include good fuel economy, high transmission efficiency, and fast shifting speed; it has become a hot research topic for major domestic and international automakers and parts companies.

[0003] Compared to dry dual-clutch automatic transmissions, wet dual-clutch automatic transmissions have advantages such as larger torque capacity, more stable performance, and longer service life, making them the preferred choice for major transmission manufacturers and vehicle manufacturers in developing DCT systems.

[0004] However, because DCT transmissions do not use a torque converter, but instead rely on two sets of clutches working in coordination and alternation, the rigid connection between the engine input and clutch output lacks a buffer zone. Even with clutch slippage, they cannot absorb the impact of rapid clutch engagement and disengagement as effectively as a torque converter. Currently, clutch torque transmission control mainly references engine torque, engine speed, input shaft speed, throttle, and braking, with engine torque being a crucial feedforward factor for clutch torque control. However, low-speed control of DCT transmissions has always been a technical challenge in China, with noticeable jerking during low-speed start-up tipout conditions (sudden release of throttle during acceleration). Summary of the Invention

[0005] This invention provides a Tipout torque control method for the start-up process of a dual-clutch transmission. This invention effectively solves the problem of continuous increase in engine torque and increased clutch torque engagement caused by "lag" factors such as engine throttle valve when releasing the accelerator, which leads to vehicle shock and improves NVH performance and driving comfort.

[0006] The technical solution to the above problem is as follows:

[0007] A tipout torque control method for the start-up process of a dual-clutch transmission includes the following steps:

[0008] S1, receive and process input signals, including throttle opening signal, clutch start-up status signal, engine start-up target speed, engine idle speed, and engine torque signal;

[0009] S2, calculate the Tipout control activation conditions based on the input signals, including: throttle opening signal, clutch start-up status, TCS control status, and engine torque. If the activation conditions are met, proceed to S3.

[0010] S3, enter Tipout control and start timing, detect the control duration in Tipout state;

[0011] S4, calculate the clutch feedforward torque based on the difference between the engine starting target speed and the engine idle speed;

[0012] S5, determine whether the control duration in Tipout state is greater than the set threshold. If the control duration in Tipout state is less than the set threshold, proceed to S6.

[0013] S6, calculate the clutch engagement torque recovery slope.

[0014] Furthermore, in S2, proceed to S3 when the following conditions are met simultaneously:

[0015] ① The throttle opening at the current moment is less than 50% and the difference between the throttle opening in the current cycle and the throttle opening 100ms ago is greater than 10%;

[0016] ② The clutch is in the starting state;

[0017] ③ The TCS flag in the ECU is not triggered;

[0018] ④ The engine torque is greater than the threshold.

[0019] Furthermore, the clutch feedforward torque calculation in S4 calculates the clutch engagement torque by the difference between the engine speed and the engine idle speed. The greater the difference between the engine starting target speed and the engine idle speed, the greater the clutch engagement torque.

[0020] Furthermore, in S6, the calculation of the clutch engagement torque recovery slope is obtained by looking up a table based on the engine torque and the difference between the clutch feedforward torque of the current cycle and the clutch feedforward torque of the previous cycle. When the engine torque is greater, the difference between the clutch feedforward torque of the current cycle and the clutch feedforward torque of the previous cycle is greater, and the clutch engagement torque recovers faster.

[0021] In this invention, after determining that the current operating condition is a Tipout condition during the start-up process, the clutch torque engagement amount is calculated by referring to the engine torque, engine speed, and idle speed difference. Simultaneously, the clutch torque value uses an independent slope limit value and recovers with a certain slope when exiting the Tipout condition to prevent sudden changes in the clutch torque value. This control method can quickly disengage the clutch when a Tipout condition is detected, effectively solving the vehicle shock caused by the continuous increase in engine torque and increased clutch torque engagement amount due to "lag" factors such as engine throttle body movement when releasing the accelerator. Vehicle testing verifies that this control method can effectively solve the Tipout shock during start-up and is of crucial significance for improving the drivability of a DCT. Attached Figure Description

[0022] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be simply construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

[0024] like Figure 1 As shown, the Tipout torque control method for the start-up process of a dual-clutch transmission of the present invention includes the following steps:

[0025] S1, Receive and process input signals. In this step, the input signals include throttle opening signal, clutch start-up status signal, engine start-up target speed, engine idle speed, and engine torque signal.

[0026] S2, calculate the Tipout control activation conditions based on the input signals, including: throttle opening signal, clutch start-up status, TCS control status, and engine torque. If the activation conditions are met, proceed to S3.

[0027] In this embodiment, S3 proceeds when the following conditions are met simultaneously in S2:

[0028] ① The throttle opening at the current moment is less than 50% and the difference between the throttle opening at the current cycle and the throttle opening 100ms ago is greater than 10%.

[0029] ② The clutch is in the starting state.

[0030] ③ The TCS flag in the ECU is not triggered.

[0031] ④ The engine torque is greater than the threshold.

[0032] S3, enter Tipout control and start timing, detect the control duration in Tipout state.

[0033] S4 calculates the clutch feedforward torque based on the difference between the engine's target starting speed and its idle speed. The clutch feedforward torque calculation in S4 uses the difference between the engine's target starting speed and its idle speed to determine the clutch engagement torque. The greater the difference between the engine's target starting speed and its idle speed, the greater the clutch engagement torque.

[0034] S5, determine whether the control duration in Tipout state is greater than the set threshold. If the control duration in Tipout state is less than the set threshold, proceed to S6.

[0035] When S3 enters Tipout control, it starts timing the Tipout control to detect the duration of control in the Tipout state. However, the duration of control in the Tipout state cannot exceed the set duration. Since Tipout control releases clutch torque, if the control time is too long, it can easily cause the engine to blow dry, and the engine speed will still rise abnormally and significantly while the driver is releasing the accelerator. If the control duration in the Tipout state exceeds the set threshold, the set duration Tipout control will exit and the timer will be reset to zero, thus preventing the engine from blowing dry.

[0036] S6 calculates the clutch engagement torque recovery slope. In S6, the clutch engagement torque recovery slope is calculated by looking up a table based on the engine torque and the difference between the clutch feedforward torque of the current cycle and the clutch feedforward torque of the previous cycle. The greater the engine torque, the greater the difference between the clutch feedforward torque of the current cycle and the clutch feedforward torque of the previous cycle, and the faster the clutch engagement torque recovers.

[0037] This invention relies on engine speed, throttle opening, and engine torque to quickly disengage the clutch when a start-up tipout condition is detected. This effectively solves the problem of vehicle shock caused by the continuous increase in engine torque and increased clutch torque engagement due to "lag" factors such as engine throttle valve movement when releasing the accelerator, thus improving NVH performance and driving comfort. Vehicle testing has verified that this control method effectively solves the start-up tipout shock and is of vital importance to improving the drivability of a DCT (Dual-clutch Transmission).

[0038] The above embodiments are some embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be simply construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A Tipout torque control method for the start-up process of a dual-clutch transmission, characterized in that, Includes the following steps: S1, receive and process input signals, including throttle opening signal, clutch start status signal, engine start target speed, engine idle speed, and engine torque signal; S2, calculate the Tipout control activation conditions based on the input signals, including: throttle opening signal, clutch start status, TCS flag status, and engine torque. If the activation conditions are met, proceed to S3. S3, enter Tipout control and start timing, detect the control duration in Tipout state; S4, calculate the clutch feedforward torque based on the difference between the engine starting target speed and the engine idle speed; S5, determine whether the control duration in Tipout state is greater than the set threshold. If the control duration in Tipout state is less than the set threshold, proceed to S6. S6, calculate the clutch engagement torque recovery slope. The clutch engagement torque recovery slope is calculated by looking up the table based on the engine torque, the difference between the clutch feedforward torque in the current cycle and the clutch feedforward torque in the previous cycle. The greater the engine torque, the greater the difference between the clutch feedforward torque in the current cycle and the clutch feedforward torque in the previous cycle, and the faster the clutch engagement torque recovers.

2. The Tipout torque control method for the starting process of a dual-clutch transmission according to claim 1, characterized in that, In S2, proceed to S3 when the following conditions are met simultaneously: ① The throttle opening at the current moment is less than 50% and the difference between the throttle opening in the current cycle and the throttle opening 100ms ago is greater than 10%; ② The clutch is in the clutch starting state; ③ The TCS flag in the ECU is not triggered; ④ The engine torque is greater than the threshold.

3. The Tipout torque control method for the starting process of a dual-clutch transmission according to claim 1, characterized in that: The clutch feedforward torque calculation in S4 is based on the difference between the engine starting target speed and the engine idle speed. The greater the difference between the engine starting target speed and the engine idle speed, the greater the clutch engagement torque.

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