Hybrid Vehicle Shifting Control for Uphill Roll-back Prevention
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Solution Overview
Problem
Hybrid vehicles equipped with Dual Clutch Transmission (DCT) experience roll-back and noise issues when shifting into lower gears on uphill slopes due to insufficient power, leading to instability and vibration.
Innovation Solution
A shifting control method that determines roll-back based on transmission input shaft speed changes, increases motor torque and engaging clutch torque, synchronizes motor speed with input shaft speed, and adjusts clutch torques to prevent roll-back and enhance stability during power-off down-shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power-off down-shifting is performed immediately before stopping on an uphill slope, then shifting speed is improved, but vehicle stability deteriorates due to roll-back
Solution Approach 1:
The controller performs preliminary detection of roll-back by monitoring transmission input shaft speed changes before the shifting is completed. When roll-back is detected, the controller preemptively increases motor torque to counteract the roll-back force, ensuring vehicle stability is maintained throughout the shifting process
2Stability of the object's composition
If motor torque is increased to prevent roll-back, then vehicle stability is improved, but device complexity increases due to additional control steps
Solution Approach 1:
The controller continuously monitors transmission input shaft speed to detect roll-back conditions in real-time. Based on this feedback, the controller dynamically adjusts motor torque to counteract roll-back, creating a closed-loop control system that maintains vehicle stability without requiring complex additional hardware
3Stability of the object's composition
If clutch torque is adjusted during shifting, then shifting smoothness is improved, but shifting time increases
Solution Approach 1:
The controller dynamically adjusts clutch torque in real-time during the shifting process based on detected roll-back conditions and transmission input shaft speed. This dynamic torque adjustment allows the shifting to proceed smoothly while maintaining efficiency, as the torque modulation is performed continuously rather than in discrete steps
Data Source
AI summary
The present disclosure relates to a shifting control method that improves driving stability by reducing roll-back of a vehicle during the process of shifting on an uphill slope. The shifting control method for a hybrid vehicle includes: determining a degree of roll-back of the vehicle on the basis of a change in the number of revolutions of a transmission input shaft, when power-off down-shifting into a lowest gear is requested; decreasing a disengaging clutch torque, increasing an engaging clutch torque, and increasing a motor torque so that the motor torque follows a desired motor torque, when the degree of roll-back is equal to or greater than a set value; synchronizing a motor speed with an engaging input shaft speed by decreasing the motor torque, when the disengaging clutch torque is equal to or less than a set torque; and finishing the shifting by increasing the motor torque when the synchronization is finished.