Dual Clutch Transmission Shifting Control for Rapid Acceleration
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Solution Overview
Problem
Dual Clutch Transmissions (DCTs) face challenges in achieving quick and direct shifting, as they rely on two clutches for gear engagement, which can result in slower shifting compared to common automatic transmissions, failing to provide a sporty shifting experience.
Innovation Solution
A shifting control method that synchronizes engine rotational speed and cooperatively controls engine torque by increasing engagement clutch torque during rapid acceleration, using a torque handover period and fuel-cut control to maintain acceleration, ensuring direct and sporty shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DCT uses two clutches for gear engagement, then gear engagement certainty is improved, but shifting speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the rotational speeds of both input shafts before the actual gear engagement occurs. The control unit calculates target rotational speeds for both input shafts in advance and begins synchronization control before the clutch actuation, ensuring that when engagement happens, the speeds are already matched, thus reducing actual shifting time while maintaining engagement certainty
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the synchronization control strategy based on real-time operating conditions. The control unit monitors engine torque, vehicle speed, and acceleration requests to adaptively modify the rotational speed synchronization profile, allowing the system to optimize shifting performance under varying dynamic conditions while maintaining reliable engagement
2Productivity
If DCT performs standard shifting control, then shifting completeness is improved, but shifting time increases
Solution Approach 1:
The control unit performs preliminary synchronization of rotational speeds before the actual torque handover and gear engagement. By pre-aligning the speeds of both input shafts and pre-positioning the clutches, the system reduces the time required for the actual shifting operation while ensuring complete and smooth engagement, thus improving productivity without sacrificing completeness
Solution Approach 2:
The patent maintains continuity of useful action by overlapping the synchronization phase with the acceleration phase. Instead of completing synchronization after torque handover, the system continues synchronization control during the torque transfer process, ensuring that the useful action of speed matching continues uninterrupted through the entire shifting sequence, reducing total shifting time while maintaining completeness
Data Source
AI summary
A vehicle is equipped with a dual clutch transmission controlled by a shifting control method to achieve quick shifting and direct engaging through quick synchronous control of the rotational speed of an engine and cooperative control of engine torque when a driver intends to rapidly accelerate the vehicle while shifting. The method includes: a rapid acceleration determining step in which a controller determines whether the vehicle is rapidly accelerated based on an output value according to a driving state of the vehicle until a torque handover period is entered, when shifting is started; and an interlocking step of controlling the engagement clutch torque over a predetermined desired engagement clutch torque to cause interlocking based on a torque value determined in accordance with a rapid acceleration level determined in the torque handover period, when the controller determines that the vehicle is rapidly accelerated.