Adaptive Torque Phase Control for DCT Engine Overrun
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Solution Overview
Problem
In vehicles with dual-clutch-transmissions (DCT), rapid acceleration can lead to engine overrun, damaging the engine and reducing performance due to delayed shifting in High Tip-In situations, making it difficult to satisfy the driver's acceleration request.
Innovation Solution
A shift control method that determines if the accelerator pedal is depressed 50% or more, estimates the time until the engine speed reaches a red zone, updates the target torque phase time, and controls the disengaging and engaging clutches to prevent engine overrun by synchronizing engine speed with the target shift-stage input shaft speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shifting is delayed in High Tip-In situation, then engine overrun is prevented, but acceleration performance deteriorates and driver's request cannot be satisfied
Solution Approach 1:
The patent applies dynamics by making the torque phase time adaptive rather than fixed. The controller dynamically adjusts the torque phase time based on real-time engine speed predictions and red zone thresholds, allowing the system to optimize between engine protection and acceleration performance under different operating conditions. This is achieved through continuous monitoring of engine angular acceleration and adjusting the disengaging and engaging clutch control accordingly.
Solution Approach 2:
The patent changes the parameter of torque phase time from a predetermined fixed value to a dynamically updated value. By calculating the predicted time to reach red zone speed and comparing it with the predetermined target torque phase time, the system updates the torque phase time parameter to ensure shifting completes before engine overrun occurs, while minimizing the impact on acceleration performance.
2Reliability
If shifting is delayed to prevent engine overrun, then engine durability is protected, but shift quality deteriorates
Solution Approach 1:
The patent applies preliminary action by predicting the future engine speed trajectory and calculating the time to reach red zone threshold before it actually occurs. The controller uses current engine speed and angular acceleration to estimate future conditions, allowing proactive adjustment of the torque phase time to ensure shifting completes just in time to prevent engine overrun while maintaining smooth shift execution.
Solution Approach 2:
The patent implements feedback by continuously monitoring engine speed, angular acceleration, and the relationship between predicted red zone arrival time and target torque phase time. This feedback loop allows the controller to dynamically adjust the torque phase time and clutch control parameters in real-time, ensuring optimal balance between engine protection and shift quality under varying operating conditions.
Data Source
AI summary
A shift control method for a rapidly accelerating DCT vehicle, may include determining, by a controller, whether or not there occurs a power-on upshift situation in which an accelerator pedal is depressed 50% or more; estimating, by the controller, a predicted time remaining until an engine speed enters a red zone when engagement of a target shift-stage gear is completed under the power-on upshift situation; and performing, by the controller, a torque phase by updating a predetermined target torque phase time to fall within the predicted time when the predicted time is less than the target torque phase time and controlling a disengaging clutch and an engaging clutch depending on the updated target torque phase time.