Shift fork pre-engagement control method for dual-clutch transmission during sudden braking

Abstract

A method for controlling shift fork pre-engagement during sudden braking of a dual-clutch transmission comprises the following steps: 1) acquiring a signal and setting a maximum forward starting gear in advance in a TCU; 2) determining whether the entire vehicle is currently in a forward gear operating state; 3) determining whether the entire vehicle is currently in an sudden braking condition; 4) determining whether both clutches are currently in an open state; 5) calculating a target pre-engagement gear for the sudden braking condition; 6) when the target pre-engagement gear is greater than the preset maximum forward starting gear, proceeding to step 7); otherwise, requesting that the shift fork be pre-engaged to the target pre-engagement gear; 7) when the odd / even shaft gear is greater than the preset maximum forward starting gear, requesting that the odd / even shaft gear greater than the preset maximum forward starting gear be shifted to neutral; otherwise, requesting that the current odd / even shaft gear remain unchanged.

Description

Technical Field

[0001] The present invention relates to the technical field of dual-clutch transmissions, and in particular to a shift fork pre-engagement control method of a dual-clutch transmission during an emergency braking process. Background Art

[0002] Dual-clutch automatic transmissions (DCTs) and DCT-based hybrid transmissions are widely used in various vehicle models. Because DCTs can pre-engage gears on both axles, the pre-engagement control method directly impacts the overall vehicle's driving experience. In some operating conditions, an inappropriate pre-engagement strategy can have a counterproductive effect, degrading the driver's driving experience. For example, if the driver suddenly brakes and then steps on the accelerator while the vehicle is in normal forward driving, the vehicle's speed drops rapidly during the sudden braking, leaving insufficient time for downshifting. Consequently, both clutches are disengaged. Subsequently, when the driver steps on the accelerator, the appropriate target gear is selected and the clutches engage. However, if the pre-gear control method is unreasonable during the process of the two clutches being opened, it will result in the driver having to return to the unreasonable pre-gear position when stepping on the accelerator, and then re-execute the target gear at this time, and then engage the clutch; if the pre-gear control method is reasonable during the process of the two clutches being opened, when the driver steps on the accelerator, there is no need to return to the neutral position and directly execute the target gear shift, or there is no need to return to the neutral position and the target gear has been engaged, and then the clutch is engaged, it will greatly optimize the vehicle acceleration response time when stepping on the accelerator, and improve the driver's driving experience. Summary of the Invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and provide a method for controlling the pre-engagement of the shift fork of a dual-clutch transmission during sudden braking, so as to solve the problem that the downshifting time is insufficient during sudden braking, and when the accelerator is pressed after the sudden braking, the gear needs to be returned to the neutral position before re-engaging.

[0004] The object of the present invention is achieved like this:

[0005] A method for controlling shift fork pre-engagement during sudden braking of a dual-clutch transmission comprises the following steps:

[0006] 1) Obtaining brake signals, transmission mode signals, vehicle deceleration signals, output shaft speed signals of the inverter, odd-numbered clutch torque signals, even-numbered clutch torque signals, odd-numbered shaft gear signals, even-numbered shaft gear signals, and the preset maximum forward gear starting position;

[0007] 2) Determine whether the vehicle is currently in a forward gear state using the transmission mode signal. If it is, proceed to step 3); otherwise, repeat step 2);

[0008] 3) Determine whether the vehicle is currently in an emergency braking condition based on the brake signal, vehicle deceleration signal, and transmission output shaft speed signal. If so, proceed to step 4); otherwise, repeat step 3 of this line.

[0009] 4) Determine whether both clutches are currently in the open state using the odd clutch torque signal and the even clutch torque signal. If they are in the open state, proceed to step 5). Otherwise, repeat step 4.

[0010] 5) Calculate the target pre-engagement gear position for emergency braking conditions based on the vehicle deceleration signal and the transmission output shaft speed signal;

[0011] 6) Comparing the target pre-engagement gear position with the preset maximum forward gear starting gear position, and when the target pre-engagement gear position is greater than the preset maximum forward gear starting gear position, proceeding to step 7); otherwise, requesting to pre-engage the shift fork to the target pre-engagement gear position;

[0012] 7) Compare the odd / even shaft gear position with the preset maximum forward gear starting gear through the odd shaft gear position signal corresponding to the odd clutch and the even shaft gear position signal corresponding to the even clutch. When the odd / even shaft gear position is greater than the preset maximum forward gear starting gear, request to adjust the odd / even shaft gear position greater than the preset maximum forward gear starting gear to neutral; otherwise, request to keep the current odd / even shaft gear position unchanged.

[0013] In step 2), when the transmission mode signal is in gear D, it is determined that the vehicle is in a forward gear running state.

[0014] In step 3), the steps for determining whether the vehicle is currently in an emergency braking condition are as follows:

[0015] 3.1) According to the output shaft speed of the transmission, set the vehicle deceleration comparison table for sudden braking of the vehicle;

[0016] 3.2) Determine whether the brake has been applied based on the brake signal. If it is, proceed to step 3.3. Otherwise, repeat step 3.2.

[0017] 3.3) Determine the vehicle deceleration threshold when the vehicle is in emergency braking based on the output shaft speed of the transmission and the vehicle deceleration comparison table for emergency braking;

[0018] 3.4) When the absolute value of the vehicle deceleration is greater than the vehicle deceleration threshold when the vehicle is in an emergency braking condition, the vehicle is currently in an emergency braking condition; otherwise, it is not in an emergency braking condition.

[0019] In step 5), the steps for calculating the target pre-engagement gear position for the emergency braking condition are as follows:

[0020] 5.1) Set the target pre-engagement gear table for emergency braking conditions based on vehicle deceleration and transmission output shaft speed;

[0021] 5.2) Based on the current vehicle deceleration signal and the transmission output shaft speed signal, the target pre-engagement gear position is obtained from the target pre-engagement gear position comparison table;

[0022] Compared to the prior art, the present invention's shift fork pre-engagement control method for a dual-clutch transmission during sudden braking optimizes the dynamic response to the driver applying the brakes and then pressing the accelerator during normal vehicle forward gear driving. During sudden braking, the pre-engagement control method is optimized. Consequently, during sudden braking, the shift fork is pre-engaged to the target pre-engagement gear, or shifted to neutral, or the gear is already engaged in the target gear. This allows the driver to directly engage the target gear when pressing the accelerator without returning to neutral, or even without returning to neutral and with the target gear already engaged. Combined with the clutch, this significantly optimizes the vehicle's acceleration response time when pressing the accelerator, enhancing the driver's driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a logical schematic diagram of the present invention. DETAILED DESCRIPTION

[0024] refer to Figure 1 A method for controlling shift fork pre-engagement during sudden braking of a dual-clutch transmission comprises the following steps:

[0025] 1) A shift fork pre-engagement control module for the dual-clutch transmission during sudden braking is set up in the TCU. This module obtains brake signals, transmission mode signals, vehicle deceleration signals, output shaft speed signals of the inverter, odd-numbered clutch torque signals, even-numbered clutch torque signals, odd-numbered shaft gear signals, and even-numbered shaft gear signals from other control modules in the TCU, and pre-sets the maximum forward starting gear in the TCU.

[0026] 2) Determine whether the vehicle is currently in the forward gear state using the transmission mode signal. When the transmission mode signal is in gear D, determine that the vehicle is in the forward gear state. If it is in the forward gear state, proceed to step 3); otherwise, repeat step 2);

[0027] 3) Determine whether the vehicle is currently in an emergency braking condition based on the brake signal, vehicle deceleration signal, and transmission output shaft speed signal. If so, proceed to step 4); otherwise, repeat step 3 of this line.

[0028] The steps to determine whether the vehicle is currently in an emergency braking condition are as follows:

[0029] 3.1) According to the output shaft speed of the transmission, set the vehicle deceleration comparison table for sudden braking of the vehicle;

[0030] The vehicle deceleration comparison table for sudden braking is shown in Table 1 below:

[0031] Table 1

[0032]

[0033] X in Table 1 i is the output shaft speed of the i-th transmission, Y j is the jth vehicle deceleration threshold corresponding to the output shaft speed of the i-th transmission.

[0034] In practice, the transmission output shaft speed can be increased or decreased, and the corresponding vehicle deceleration value can be increased or decreased accordingly. Generally speaking, the higher the transmission output shaft speed, the greater the absolute value of the corresponding vehicle deceleration. The values ​​in Table 1 can be calibrated and confirmed during the vehicle calibration and verification process.

[0035] 3.2) Determine whether the brake has been applied based on the brake signal. If it is, proceed to step 3.3. Otherwise, repeat step 3.2.

[0036] 3.3) Determine the vehicle deceleration threshold when the vehicle is in emergency braking based on the output shaft speed of the transmission and the vehicle deceleration comparison table for emergency braking;

[0037] 3.4) When the absolute value of the vehicle deceleration is greater than the vehicle deceleration threshold when the vehicle is in an emergency braking condition, the vehicle is currently in an emergency braking condition; otherwise, it is not in an emergency braking condition.

[0038] 4) Determine whether both clutches are currently in the open state using the odd clutch torque signal and the even clutch torque signal. If they are in the open state, proceed to step 5). Otherwise, repeat step 4.

[0039] 5) Calculate the target pre-engagement gear position for emergency braking conditions based on the vehicle deceleration signal and the transmission output shaft speed signal;

[0040] The steps to calculate the target pre-engagement gear for emergency braking are as follows:

[0041] 5.1) Set the target pre-engagement gear table for emergency braking conditions based on vehicle deceleration and transmission output shaft speed;

[0042] The target pre-engagement gear comparison table for emergency braking conditions is shown in Table 2 below:

[0043] Table 2

[0044]

[0045] X in Table 2i is the output shaft speed of the i-th transmission, Y j is the jth vehicle deceleration threshold, Z ij is the target pre-engagement gear position corresponding to the output shaft speed of the i-th transmission and the j-th vehicle deceleration threshold.

[0046] In practice, the transmission output shaft speed and vehicle deceleration thresholds can be increased or decreased, and the corresponding target pre-gear position values ​​should be increased or decreased accordingly. Generally, when the transmission output shaft speed remains constant, the greater the absolute value of the vehicle deceleration, the lower the corresponding target pre-gear position should be. When the vehicle deceleration remains constant, the higher the transmission output shaft speed, the higher the corresponding target pre-gear position. The values ​​in Table 2 can be verified during vehicle calibration and verification.

[0047] 5.2) Based on the current vehicle deceleration signal and the transmission output shaft speed signal, the target pre-engagement gear position is obtained from the target pre-engagement gear position comparison table;

[0048] 6) Comparing the target pre-engagement gear position with the preset maximum forward gear starting gear position, and when the target pre-engagement gear position is greater than the preset maximum forward gear starting gear position, proceeding to step 7); otherwise, issuing a request to pre-engage the shift fork to the target pre-engagement gear position;

[0049] 7) Using the odd-numbered shaft gear position signal corresponding to the odd-numbered clutch and the even-numbered shaft gear position signal corresponding to the even-numbered clutch, the odd / even-numbered shaft gear position is compared with the preset maximum forward gear start position. If the odd / even-numbered shaft gear position is greater than the preset maximum forward gear start position, a request is issued to shift the odd / even-numbered shaft gear position greater than the preset maximum forward gear start position to neutral; the shift fork is shifted to neutral. Otherwise, a request is issued to maintain the current odd / even-numbered shaft gear position, and the shift fork maintains the current gear position.

[0050] The present invention improves the response time of a dual-clutch automatic transmission when the vehicle brakes suddenly and then presses the accelerator while driving in a forward gear. By identifying this operating condition, the system optimizes the pre-engagement gear selection when the vehicle brakes suddenly and the clutch is engaged. This allows the customer to select a speed range that requires high acceleration and is easily perceived when pressing the accelerator, avoiding the need to return to neutral before engaging the target gear. Alternatively, the system can pre-engage the target gear whenever possible, saving time during the gear-engagement process. This optimizes the acceleration response time when pressing the accelerator, improving the driving experience.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for controlling the pre-engagement of a shift fork during sudden braking of a dual-clutch transmission, characterized by: The following steps are involved: 1) Obtaining brake signals, transmission mode signals, vehicle deceleration signals, transmission output shaft speed signals, odd-numbered clutch torque signals, even-numbered clutch torque signals, odd-numbered shaft gear signals, even-numbered shaft gear signals, and the pre-set forward gear maximum starting gear; 2) Determine whether the vehicle is currently in a forward gear state using the transmission mode signal. If it is, proceed to step 3); otherwise, repeat step 2); 3) Determine whether the vehicle is currently in an emergency braking condition based on the brake signal, vehicle deceleration signal, and transmission output shaft speed signal. If so, proceed to step 4); otherwise, repeat step 3 of this line. 4) Determine whether both clutches are currently in the open state using the odd clutch torque signal and the even clutch torque signal. If they are in the open state, proceed to step 5). Otherwise, repeat step 4. 5) Calculate the target pre-engagement gear position for emergency braking conditions based on the vehicle deceleration signal and the transmission output shaft speed signal; 6) Comparing the target pre-engagement gear position with the preset maximum forward gear starting gear position, and when the target pre-engagement gear position is greater than the preset maximum forward gear starting gear position, proceeding to step 7); otherwise, requesting to pre-engage the shift fork to the target pre-engagement gear position; 7) Compare the odd / even shaft gear position with the preset maximum forward gear starting gear through the odd shaft gear position signal corresponding to the odd clutch and the even shaft gear position signal corresponding to the even clutch. When the odd / even shaft gear position is greater than the preset maximum forward gear starting gear, request to adjust the odd / even shaft gear position greater than the preset maximum forward gear starting gear to neutral; otherwise, request to keep the current odd / even shaft gear position unchanged.

2. The method for controlling the shift fork pre-engagement during sudden braking of a dual-clutch transmission according to claim 1, characterized in that: In step 2), when the transmission mode signal is in gear D, it is determined that the vehicle is in a forward gear running state.

3. The method for controlling the shift fork pre-engagement during sudden braking of a dual-clutch transmission according to claim 1, characterized in that: In step 3), the steps for determining whether the vehicle is currently in an emergency braking condition are as follows: 3.1) According to the output shaft speed of the transmission, set the vehicle deceleration comparison table for sudden braking of the vehicle; 3.2) Determine whether the brake has been applied based on the brake signal. If it is, proceed to step 3.

3. Otherwise, repeat step 3.

2. 3.3) Determine the vehicle deceleration threshold when the vehicle is in emergency braking based on the output shaft speed of the transmission and the vehicle deceleration comparison table for emergency braking; 3.4) When the absolute value of the vehicle deceleration is greater than the vehicle deceleration threshold when the vehicle is in an emergency braking condition, the vehicle is currently in an emergency braking condition; otherwise, it is not in an emergency braking condition.

4. The method for controlling the shift fork pre-engagement during sudden braking of a dual-clutch transmission according to claim 1, characterized in that: In step 5), the steps for calculating the target pre-engagement gear position for the emergency braking condition are as follows: 5.1) Set the target pre-engagement gear table for emergency braking conditions based on vehicle deceleration and transmission output shaft speed; 5.2) Based on the current vehicle deceleration signal and the transmission output shaft speed signal, the target pre-engagement gear position is obtained from the target pre-engagement gear position comparison table.

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