Dual-Clutch Transmission Downshift Control for Faster Acceleration
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Solution Overview
Problem
Existing methods for controlling automatic transmissions, particularly double clutch transmissions, often result in inefficient gear shifts that lead to acceleration delays and dips, negatively affecting the vehicle's acceleration curve due to long shifting times and unnecessary gear changes.
Innovation Solution
The method involves calculating and selecting the target gear that achieves the highest vehicle acceleration over a specific acceleration period by optimizing downshifts and considering factors like shifting processes, terrain incline, vehicle loading, and temperature, to minimize shifting operations and times, thereby improving the acceleration profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed shift points are used based on engine speed and vehicle speed, then the transmission control is simple, but acceleration delays and dips occur
Solution Approach 1:
The patent applies dynamics by transitioning from fixed shift points to dynamic shift point determination. The control unit calculates optimal shift points in real-time based on current operating conditions (engine speed, vehicle speed, accelerator pedal position, selected program) and predicts acceleration curves for different shift scenarios. This allows the transmission to adapt dynamically to changing conditions, eliminating acceleration delays while maintaining control simplicity through automated calculations.
2Productivity
If multiple downshift operations are performed to reach a lower target gear, then the vehicle can achieve higher acceleration in that gear, but the total shifting time increases
Solution Approach 1:
The patent applies preliminary action by calculating and comparing complete acceleration curves for different downshift strategies before executing any shift. The control unit predicts the acceleration outcome for direct downshifts (e.g., 6th to 3rd gear) versus multi-step downshifts (e.g., 6th to 5th to 2nd gear), considering all intermediate shift operations. This advance calculation allows selection of the optimal path that maximizes acceleration while minimizing total shifting time, rather than following predetermined shift patterns.
3Stability of the object's composition
If intermediate gears are used during downshifting, then the shifting process is smoother, but the acceleration curve is disrupted
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting shift based on calculated acceleration curves. Rather than always using intermediate gears for smoothness or always direct-shifting for acceleration, the control unit calculates the optimal approach for each specific situation. The system changes the shift strategy parameters (direct vs. intermediate gears) based on real-time conditions, selecting the path that maintains the best acceleration curve while achieving necessary smoothness when beneficial.
Data Source
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Figure 1b
AI summary
The invention relates to a method for controlling an automatic transmission, in particular a dual-clutch gearbox, wherein at least one or more downshifts are performed during an acceleration process of the vehicle and a target gear is selected proceeding from a source gear. The acceleration characteristic is improved in that the vehicle acceleration concerned is calculated for a downshift into a first target gear and for at least one downshift into at least one second higher target gear over an anticipated specific acceleration period (ΔtB) and taking into consideration anticipated shift processes in the anticipated specific acceleration period (ΔtB) and that target gear is selected as the target gear which allows the greatest vehicle acceleration or requires the fewest shift processes over the anticipated specific acceleration period (ΔtB).