Control method for reducing NVH noise of dual clutch transmission

Abstract

A control method for reducing NVH noise in a dual-clutch transmission comprises the following steps: 1) obtaining an engine torque threshold and setting a speed synchronization error threshold between the engine and a DCT input shaft; 2) entering an NVH noise control phase when the following conditions are simultaneously met: ① the throttle opening at the current moment is greater than zero and the throttle opening at the previous moment is zero; ② the DCT is not in the shifting process; ③ the TCS flag in the ECU is not triggered; ④ the real-time engine output torque is less than the engine torque threshold; 3) controlling the real-time engine output torque and the real-time clutch control torque in the following manner: 3-1) adjusting the real-time engine output torque; 3-2) obtaining a clutch control percentage; 3-3) if the difference between the real-time engine speed and the real-time DCT input shaft speed is greater than the speed synchronization error threshold, calculating a clutch target control torque and adjusting the clutch real-time control torque according to the calculated clutch target control torque.

Description

Technical Field

[0001] The present invention relates to the field of dual-clutch transmissions, and in particular to a control method for reducing NVH noise of a dual-clutch transmission. Background Art

[0002] Dual-clutch transmissions (DCTs), also known as "dual clutch transmissions," are often referred to as "dual clutch transmissions" because they have two clutches. DCTs have their origins in motorsport, first being used on some racing cars in the 1980s. With over 20 years of history, the technology is now highly mature.

[0003] The two clutches in a DCT are connected to two input shafts. Shifting and clutching are handled by a mechatronic module integrating electronic and hydraulic components, rather than a clutch pedal. Each clutch is connected to a different input shaft. While the first clutch is connected to 1st, 3rd, and 5th gears via a solid shaft, the second clutch is connected to 2nd, 4th, 6th, and reverse gears via a hollow shaft.

[0004] In layman's terms, this gearbox has two clutches, one controls 1, 3, and 5 gears, and the other controls 2, 4, and 6. When using first gear, second gear is already ready, so the shifting time is greatly shortened and there is no delay.

[0005] Due to the friction torque of the engine, the engine torque is negative during vehicle coasting, and the vehicle's power is transmitted from the wheels to the transmission input shaft and then to the engine. If the driver steps on the accelerator during this process, causing the throttle depth to change by more than 50%, and the throttle change rate (the change in throttle travel per second) exceeds 100%, the vehicle enters the tip-in state. At this time, the engine torque changes from negative torque to positive torque, the power transmission of the entire vehicle changes, and the direction of transmission gear meshing will also change. Due to the presence of gear tooth backlash, the gears will knock at the moment the vehicle's power transmission changes. The knock energy is transmitted to the housing and the interior of the vehicle through the bearings, causing impact vibration (jerk) and gear clashing sounds in the vehicle body, greatly reducing passenger comfort. Summary of the Invention

[0006] The purpose of the present invention is to address the corresponding deficiencies in the existing technology and provide a control method for reducing the NVH noise of a dual-clutch transmission. During the Tipin process, the real-time output torque of the engine is limited, and at the same time, the clutch torque engagement amount is controlled to cause the clutch to form sliding friction to absorb impact, thereby eliminating the impact sound caused by gear clearance, reducing the impact of the NVH noise of the dual-clutch transmission during driving, and improving ride comfort.

[0007] The object of the present invention is to achieve the following: a control method for reducing NVH noise of a dual-clutch transmission, comprising the following steps:

[0008] 1) Based on the DCT real-time gear position, real-time vehicle speed, and a two-dimensional table of engine torque thresholds, the engine torque threshold is obtained and the speed synchronization error threshold between the engine and the DCT input shaft is set;

[0009] 2) When the following conditions are met at the same time, the NVH noise control stage begins:

[0010] ① The current throttle opening is greater than zero, and the throttle opening at the previous moment was zero;

[0011] ②DCT is not in the gear shifting process;

[0012] ③The TCS flag in the ECU is not triggered;

[0013] ④The real-time output torque of the engine is less than the engine torque threshold;

[0014] 3) During the NVH noise control phase, the engine real-time output torque and the clutch real-time control torque are controlled as follows:

[0015] 3-1) Using the engine torque recovery slope to adjust the real-time engine output torque;

[0016] 3-2) Obtaining the clutch control percentage based on the DCT real-time gear position and the clutch control percentage one-dimensional table;

[0017] 3-3) If the difference between the real-time engine speed and the real-time DCT input shaft speed is greater than the speed synchronization error threshold, the clutch target control torque is calculated using the following formula, and the real-time clutch control torque is adjusted according to the calculated clutch target control torque:

[0018] Clutch target control torque = engine real-time output torque × clutch control percentage + clutch engagement torque correction value.

[0019] Preferably, the two-dimensional table of engine torque threshold value and the one-dimensional table of clutch control percentage are both obtained through a whole vehicle NVH noise control calibration test.

[0020] Preferably, the clutch engagement torque correction value is obtained by querying a clutch engagement torque correction two-dimensional table according to the difference between the real-time engine speed and the real-time DCT input shaft speed and the rate of change of the difference.

[0021] Preferably, the clutch engagement torque correction two-dimensional table is obtained through a vehicle NVH noise control calibration test.

[0022] Preferably, the engine torque recovery slope is obtained by querying an engine torque recovery slope two-dimensional table according to the current gear and the engine target torque of the previous cycle.

[0023] Preferably, the engine torque recovery slope two-dimensional table is obtained through a vehicle NVH noise control calibration test.

[0024] Preferably, before comparing the difference between the real-time engine speed and the real-time DCT input shaft speed with the speed synchronization error threshold, the real-time engine speed and the real-time DCT input shaft speed are subjected to difference filtering.

[0025] Preferably, a NVH noise control stage duration threshold is set, and if the processing time of the NVH noise control stage exceeds the NVH noise control stage duration threshold, the NVH noise control stage is immediately exited.

[0026] Preferably, in the NVH noise control stage, if the engine target torque is greater than the engine real-time output torque, the NVH noise control stage is immediately exited.

[0027] Preferably, in the NVH noise control stage, if the difference between the real-time engine speed and the real-time DCT input shaft speed is less than or equal to the speed synchronization error threshold, the NVH noise control stage is immediately exited.

[0028] The advantage of the present invention is that a pre-calibrated engine torque threshold is used to limit the real-time output torque of the engine, so as to minimize the impact sound caused by gear clearance during the tipin process, and the slip generated by the clutch is utilized to avoid the impact vibration caused by the sudden change of the real-time output torque of the engine, thereby improving the NVH performance of the vehicle and the driving comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of the present invention;

[0030] Figure 2 This is a flow chart of the NVH noise control stage in the present invention. DETAILED DESCRIPTION

[0031] like Figures 1 to 2 As shown, a control method for reducing NVH noise of a dual-clutch transmission includes the following steps:

[0032] 1) Based on the DCT real-time gear position, real-time vehicle speed, and a two-dimensional table of engine torque thresholds, the engine torque threshold is obtained and the speed synchronization error threshold between the engine and the DCT input shaft is set;

[0033] 2) When the following conditions are met at the same time, the NVH noise control stage begins:

[0034] ① The current throttle opening is greater than zero, and the throttle opening at the previous moment was zero;

[0035] ②DCT is not in the gear shifting process;

[0036] ③The TCS flag in the ECU is not triggered;

[0037] ④ The real-time output torque of the engine is less than the engine torque threshold. In this embodiment, the engine torque threshold is 5 N·m;

[0038] 3) During the NVH noise control phase, the engine real-time output torque and the clutch real-time control torque are controlled as follows:

[0039] 3-1) Using the engine torque recovery slope to adjust the real-time engine output torque;

[0040] The engine torque recovery slope is obtained by querying an engine torque recovery slope two-dimensional table according to the current gear and the engine target torque of the previous cycle. The engine torque recovery slope two-dimensional table is obtained through a vehicle NVH noise control calibration test.

[0041] 3-2) Obtaining the clutch control percentage based on the DCT real-time gear position and the clutch control percentage one-dimensional table;

[0042] 3-3) If the difference between the real-time engine speed and the real-time DCT input shaft speed is greater than the speed synchronization error threshold, the clutch target control torque is calculated using the following formula, and the real-time clutch control torque is adjusted according to the calculated clutch target control torque:

[0043] Clutch target control torque = engine real-time output torque × clutch control percentage + clutch engagement torque correction value.

[0044] In order to gently eliminate the knocking sound caused by gear clearance during the tipin process, the engine's real-time output torque is limited by the engine torque threshold. At this time, the clutch's real-time control torque begins to decrease until it reaches the clutch control percentage corresponding to the current gear. When the engine's real-time output torque is equal to the engine torque threshold, the engine's target torque begins to rise. The engine's real-time output torque rises with the engine's target torque, and partial slippage will occur. The clutch's real-time control torque also rises with the increase in the engine's real-time output torque. The speed difference between the engine's real-time speed and the input shaft's real-time speed is used for closed-loop control to stabilize the slippage.

[0045] As the engine's real-time output torque increases and exceeds the current engine target torque, the clutch's real-time control torque increases further, allowing the engine's real-time speed to be smoothly synchronized with the input shaft's real-time speed, and the clutch produces slippage, avoiding the impact vibration caused by sudden changes in the engine's real-time output torque, thereby improving NVH performance and driving comfort.

[0046] In this embodiment, before comparing the difference between the real-time engine speed and the real-time DCT input shaft speed with the speed synchronization error threshold, the real-time engine speed and the real-time DCT input shaft speed are subjected to difference filtering.

[0047] The clutch engagement torque correction value is obtained by querying a clutch engagement torque correction two-dimensional table based on the difference between the real-time engine speed and the real-time DCT input shaft speed and the rate of change of the difference. The clutch engagement torque correction two-dimensional table is obtained through a vehicle NVH noise control calibration test.

[0048] The two-dimensional table of engine torque threshold and the one-dimensional table of clutch control percentage are both obtained through the whole vehicle NVH noise control calibration test, and the data in the two-dimensional table of engine torque threshold and the one-dimensional table of clutch control percentage are calibration values.

[0049] During the NVH noise control stage, if the engine target torque is greater than the engine real-time output torque, the NVH noise control stage will be exited immediately.

[0050] During the NVH noise control stage, if the difference between the real-time engine speed and the real-time DCT input shaft speed is less than or equal to the speed synchronization error threshold, the NVH noise control stage is immediately exited.

[0051] This embodiment also provides an NVH noise control stage duration threshold. If the processing time of the NVH noise control stage exceeds the NVH noise control stage duration threshold, the NVH noise control stage will be exited immediately. The NVH noise control stage duration threshold is obtained through the whole vehicle NVH noise control calibration test, which is generally 1200ms.

[0052] The specific method of the vehicle NVH noise control calibration test is as follows:

[0053] ① Test with different differences between the real-time engine speed and the real-time DCT input shaft speed, observe the longitudinal acceleration of the vehicle, and use the difference between the real-time engine speed and the real-time DCT input shaft speed corresponding to the minimum longitudinal acceleration as the speed synchronization error threshold. Generally, the speed synchronization error threshold is 50rpm.

[0054] ② Conduct tests at various vehicle speeds using different DCT gears to observe the vehicle's longitudinal acceleration. Record the corresponding engine torque at the minimum longitudinal acceleration for each DCT gear at different vehicle speeds to create a two-dimensional table of engine torque thresholds.

[0055] ③ Conduct tests using different engine torque recovery slopes in different DCT gears. Record the engine target torque and engine torque recovery slope of the previous cycle corresponding to the minimum vehicle longitudinal acceleration in each gear, and form a two-dimensional table of engine torque recovery slopes.

[0056] ④ Test with different clutch control percentages in different DCT gears, record the clutch control percentage corresponding to the minimum vehicle longitudinal acceleration in each gear, and form a one-dimensional table of clutch control percentages.

[0057] ⑤ Compare the vehicle longitudinal acceleration corresponding to several durations of the NVH noise control stage, and take the duration corresponding to the minimum vehicle longitudinal acceleration as the NVH noise control stage duration threshold.

[0058] ⑥ Use the difference and difference change rate of several real-time engine speeds and DCT input shaft speeds to conduct tests. According to the longitudinal acceleration of the vehicle, record the optimal data and form a two-dimensional table of clutch engagement torque correction.

[0059] 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 control method for reducing NVH noise of a dual-clutch transmission, characterized in that: The following steps are involved: 1) Based on the DCT real-time gear position, real-time vehicle speed, and a two-dimensional table of engine torque thresholds, the engine torque threshold is obtained and the speed synchronization error threshold between the engine and the DCT input shaft is set; 2) When the following conditions are met at the same time, the NVH noise control stage begins: ① The current throttle opening is greater than zero, and the throttle opening at the previous moment was zero; ②DCT is not in the gear shifting process; ③The TCS flag in the ECU is not triggered; ④The real-time output torque of the engine is less than the engine torque threshold; 3) During the NVH noise control phase, the engine real-time output torque and the clutch real-time control torque are controlled as follows: 3-1) Using the engine torque recovery slope to adjust the real-time engine output torque; 3-2) Obtaining the clutch control percentage based on the DCT real-time gear position and the clutch control percentage one-dimensional table; 3-3) If the difference between the real-time engine speed and the real-time DCT input shaft speed is greater than the speed synchronization error threshold, the clutch target control torque is calculated using the following formula, and the real-time clutch control torque is adjusted according to the calculated clutch target control torque: Clutch target control torque = engine real-time output torque × clutch control percentage + clutch engagement torque correction value.

2. The control method for reducing NVH noise of a dual-clutch transmission according to claim 1, characterized in that: The two-dimensional table of engine torque threshold value and the one-dimensional table of clutch control percentage are both obtained through the whole vehicle NVH noise control calibration test.

3. The control method for reducing NVH noise of a dual-clutch transmission according to claim 1, characterized in that: The clutch engagement torque correction value is obtained by querying a clutch engagement torque correction two-dimensional table according to the difference between the real-time engine speed and the real-time DCT input shaft speed and the rate of change of the difference.

4. The control method for reducing NVH noise of a dual-clutch transmission according to claim 3, characterized in that: The clutch engagement torque correction two-dimensional table is obtained through a vehicle NVH noise control calibration test.

5. The control method for reducing NVH noise of a dual-clutch transmission according to claim 1, characterized in that: The engine torque recovery slope is obtained by querying the engine torque recovery slope two-dimensional table according to the current gear and the engine target torque of the previous cycle.

6. The control method for reducing NVH noise of a dual-clutch transmission according to claim 5, characterized in that: The engine torque recovery slope two-dimensional table is obtained through a vehicle NVH noise control calibration test.

7. The control method for reducing NVH noise of a dual clutch transmission according to claim 1, characterized in that: Before comparing the difference between the real-time engine speed and the real-time DCT input shaft speed with the speed synchronization error threshold, the real-time engine speed and the real-time DCT input shaft speed are subjected to difference filtering.

8. The control method for reducing NVH noise of a dual-clutch transmission according to claim 1, characterized in that: Set the NVH noise control stage duration threshold. If the processing time of the NVH noise control stage exceeds the NVH noise control stage duration threshold, the NVH noise control stage will be exited immediately.

9. The control method for reducing NVH noise of a dual-clutch transmission according to claim 1, characterized in that: During the NVH noise control stage, if the engine target torque is greater than the engine real-time output torque, the NVH noise control stage will be exited immediately.

10. The control method for reducing NVH noise of a dual clutch transmission according to claim 1, characterized in that: During the NVH noise control stage, if the difference between the real-time engine speed and the real-time DCT input shaft speed is less than or equal to the speed synchronization error threshold, the NVH noise control stage is immediately exited.

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