Method for controlling Tipout torque in starting process of dual-clutch transmission

Abstract

The invention discloses a Tipout torque control method in the starting process of a dual-clutch transmission. The Tipout torque control method comprises the steps that an input signal is received and processed; calculating Tipout control activation conditions according to the input signal, wherein the Tipout control activation conditions comprise an accelerator opening signal, a clutch starting state, a TCS control state and an engine real torque; s3, entering Tipout control and starting timing, and detecting the control duration time in a Tipout state; s4, the clutch feed-forward torque is calculated according to the difference value between the target rotating speed and the idle speed of the engine; s5, judging whether the control duration time in the Tipout state is greater than a set threshold value or not; and S6, the clutch combination torque recovery slope is calculated. According to the invention, the problem of whole vehicle impact caused by continuous increase of engine torque and increase of clutch torque combination amount when an accelerator is loosened due to'delay 'factors such as an engine throttle valve is well solved, and NVH performance and driving comfort are improved.

Description

Technical Field

[0001] The invention relates to the field of automobile dual-clutch automatic transmissions, and in particular to a torque control method for a Tipout condition during a dual-clutch transmission starting process. Background Art

[0002] The DCT transmission uses two clutches corresponding to two input shafts respectively, and realizes uninterrupted power transmission through the cooperation of the offgoing clutch and the oncoming clutch. DCT not only inherits the advantages of traditional manual transmission such as high transmission efficiency, compact structure and low cost, but also has the good characteristics of uninterrupted power and fast and smooth gear shifting during driving. The characteristics of DCT are good fuel economy, high transmission efficiency and fast gear shifting; it has become a hot research topic for major domestic and foreign vehicle manufacturers and parts companies.

[0003] Compared with dry dual-clutch automatic transmission, wet dual-clutch automatic transmission has the advantages of large torque capacity, stable working performance and long service life. Therefore, it has become the first choice for major transmission companies and vehicle companies to develop DCT systems.

[0004] However, since the DCT transmission does not use a torque converter, but instead uses two sets of clutches to coordinate and work alternately, the engine input end and the clutch output end are rigidly connected without a buffer zone. Even through clutch slip, the impact caused by the rapid engagement and separation of the clutch cannot be absorbed as well as a torque converter. At present, the clutch transmission torque control mainly refers to engine torque, engine speed, input shaft speed, throttle, brake, etc., among which engine torque is a crucial feedforward link for clutch torque control. However, the low-speed control of the DCT transmission has always been a technical difficulty in China, and the low-speed starting Tipout condition (suddenly releasing the accelerator during the process of starting) has obvious setbacks. Summary of the invention

[0005] The present invention provides a Tipout torque control method during the starting process of a dual-clutch transmission. The present invention effectively solves the problem of the engine torque continuously rising when the accelerator is released due to "hysteresis" factors such as the engine throttle, and the impact on the whole vehicle caused by the increase in the clutch torque engagement, thereby improving NVH and driving comfort.

[0006] The technical solutions to the above problems are as follows: A method for controlling a Tipout torque during a starting process of a dual clutch transmission comprises the following steps: S1, receives and processes input signals; S2, calculate the Tipout control activation conditions according to the input signals, including: throttle opening signal, clutch starting state, TCS control state, engine real torque. If the activation conditions are met, enter S3; S3, enter Tipout control and start timing to detect the control duration in the Tipout state; S4, calculating the clutch feedforward torque according to the difference between the engine target speed and the idle speed; S5, judging whether the control duration in the Tipout state is greater than the set threshold. If the control duration in the Tipout state is less than the set threshold, entering S6; S6, calculating the clutch engagement torque recovery slope.

[0007] Furthermore, the input signal in S1 includes a throttle opening signal, a clutch starting state signal, an engine starting target speed, an engine idle speed, and an engine torque signal.

[0008] Furthermore, when the following conditions are met at the same time in S2, enter S3: ① The current throttle opening is less than 50% and the difference between the current cycle throttle opening and the throttle opening 100ms ago is greater than 10%; ② The clutch is in the starting state; ③ The TCS flag in the ECU is not triggered; ④ The engine torque is greater than the threshold.

[0009] Furthermore, the clutch feedforward torque calculation in S4 calculates the clutch engagement torque by the difference between the engine speed and the idle speed. The greater the difference between the starting target speed and the engine idle speed, the greater the clutch torque engagement.

[0010] Furthermore, in S6, the clutch recovery slope is calculated based on the engine torque and the difference between the clutch feedforward torque of this cycle and the feedforward torque of the previous cycle. The greater the engine torque, the greater the difference between the feedforward torque of this cycle and the feedforward torque of the previous cycle, and the faster the clutch torque recovers.

[0011] In the present invention, after determining that the current working condition is the Tipout working condition of the starting process, the clutch torque engagement amount is calculated by referring to the engine torque, the engine speed and the idle speed difference respectively under this working condition; at the same time, the clutch torque value uses an independent slope limit value, and is restored at a certain slope when exiting the Tipout working condition to prevent the clutch torque value from changing suddenly. This control method can quickly disengage the clutch when the Tipout working condition of starting is detected, and well solves the problem of the engine torque continuously rising when the accelerator is released due to "hysteresis" factors such as the engine throttle, and the whole vehicle impact caused by the increase in the clutch torque engagement amount. The whole vehicle test verification shows that this control method can well solve the Tipout impact of starting, which is of vital significance to improving the driving performance of DCT. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention are described in more detail below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and cannot be simply understood as limitations on the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings: like Figure 1 As shown, the Tipout torque control method of the dual clutch transmission starting process of the present invention comprises the following steps: S1, receiving and processing input signals. In this step, the input signals include throttle opening signal, clutch starting state signal, engine starting target speed, engine idle speed, and engine torque signal.

[0014] S2, calculate the Tipout control activation conditions based on the input signals, including: throttle opening signal, clutch starting state, TCS control state, engine real torque. If the activation conditions are met, enter S3.

[0015] In this embodiment, when the following conditions are met at the same time in S2, the process proceeds to S3: ① The current throttle opening is less than 50% and the difference between the current cycle throttle opening 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] S3, enter Tipout control and start timing to detect the control duration in the Tipout state.

[0020] S4, calculates the clutch feedforward torque according to the difference between the engine target speed and the idle speed. The clutch feedforward torque calculation in S4 calculates the clutch engagement torque by the difference between the engine speed and the idle speed. The greater the difference between the starting target speed and the engine idle speed, the greater the clutch torque engagement.

[0021] S5, judging whether the control duration in the Tipout state is greater than a set threshold value, if the control duration in the Tipout state is less than the set threshold value, entering S6.

[0022] When S3 enters Tipout control, the Tipout control is timed to detect the control duration in the Tipout state. However, the control duration in the Tipout state cannot be greater than the set duration. Since the Tipout control releases the clutch torque, if the control time is too long, it is easy to cause the engine to blow dry, and the engine speed will still increase abnormally and significantly when the driver releases the accelerator. If the control duration in the Tipout state is greater than the set threshold, the Tipout control with the set duration is exited and the timing is reset to zero to avoid engine blowing dry.

[0023] S6, calculating the clutch engagement torque recovery slope. In S6, the clutch recovery slope is calculated by looking up the table based on the engine torque and the difference between the clutch feedforward torque of this cycle and the feedforward torque of the previous cycle. When the engine torque is larger, the difference between the feedforward torque of this cycle and the feedforward torque of the previous cycle is larger, and the clutch torque recovery is faster.

[0024] The present invention relies on the engine speed, throttle opening, and engine torque to quickly disengage the clutch when the starting Tipout condition is detected, which effectively solves the problem of the engine torque continuing to rise when the throttle is released due to "hysteresis" factors such as the engine throttle, and the vehicle impact caused by the increase in the clutch torque engagement, thereby improving NVH and driving comfort. The vehicle test verification shows that the control method can effectively solve the starting Tipout impact, which is of vital importance to improving the driving performance of DCT.

[0025] The above embodiments are part of the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but cannot be simply understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

Claims

1. A Tipout torque control method for a dual clutch transmission starting process, characterized in that: The following steps are involved: S1, receives and processes input signals; S2, calculate the Tipout control activation conditions according to the input signals, including: throttle opening signal, clutch starting state, TCS control state, engine real torque. If the activation conditions are met, enter S3; S3, enter Tipout control and start timing to detect the control duration in the Tipout state; S4, calculating the clutch feedforward torque according to the difference between the engine target speed and the idle speed; S5, judging whether the control duration in the Tipout state is greater than the set threshold. If the control duration in the Tipout state is less than the set threshold, entering S6; S6, calculating the clutch engagement torque recovery slope.

2. The torque control method for a dual clutch transmission in a Tipout condition during starting according to claim 1, characterized in that: The input signal in S1 includes a throttle opening signal, a clutch starting state signal, an engine starting target speed, an engine idle speed, and an engine torque signal.

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

4. The torque control method for a dual clutch transmission in a Tipout condition during starting according to claim 1, characterized in that: The clutch feedforward torque calculation in S4 calculates the clutch engagement torque by the difference between the engine speed and the idle speed. The greater the difference between the starting target speed and the engine idle speed, the greater the clutch torque engagement.

5. The torque control method for a dual clutch transmission in a Tipout condition during starting according to claim 1, characterized in that: In S6, the clutch recovery slope is calculated by looking up the table based on the engine torque and the difference between the clutch feedforward torque of this cycle and the feedforward torque of the previous cycle. The greater the engine torque, the greater the difference between the feedforward torque of this cycle and the feedforward torque of the previous cycle, and the faster the clutch torque recovery.

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