DCT Creep Torque Release Logic for Shift Before Stop
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Solution Overview
Problem
Dual clutch transmission (DCT) vehicles face challenges in creep torque control during shifts before stopping, as existing methods optimized for automatic transmissions result in excessively lowered coasting speeds and require differentiated release conditions, leading to inefficiencies and potential starting issues.
Innovation Solution
A method for releasing creep torque control in DCT vehicles that considers the current shift gear position and vehicle speed, releasing control when actual creep torque equals the target creep torque, or when the vehicle is in a parking, reverse, or neutral position, to optimize shift execution and prevent starting delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If creep torque control is applied to DCT vehicles during shift before stop, then shift smoothness is improved, but vehicle speed is excessively lowered and starting may be delayed
Solution Approach 1:
The patent changes the creep torque parameter from negative to positive specifically for DCT vehicles during shift before stop conditions. This parameter change resolves the contradiction by eliminating the excessive speed reduction and starting delay while maintaining shift smoothness through controlled positive torque application.
Solution Approach 2:
The patent implements dynamic adjustment of creep torque control based on vehicle operating conditions (gear position, vehicle speed, accelerator pedal position). The control system dynamically switches between applying and releasing creep torque control, optimizing both shift smoothness and vehicle speed maintenance for DCT vehicles.
2Speed
If creep torque control is released early in DCT vehicles, then vehicle speed is maintained, but shift feeling deteriorates due to insufficient torque control
Solution Approach 1:
The patent changes the creep torque sign parameter to positive for DCT vehicles, which fundamentally alters the torque control behavior. This enables the system to maintain vehicle speed while still providing adequate torque control for acceptable shift feeling during shift before stop conditions.
Solution Approach 2:
The patent applies creep torque control in advance during the shift before stop process, proactively managing torque to ensure smooth shifting while controlling the duration and magnitude of torque application to prevent excessive speed reduction.
3Device complexity
If conventional automatic transmission creep torque control logic is applied to DCT, then control simplicity is maintained, but differentiation of release conditions becomes necessary due to different torque characteristics
Solution Approach 1:
The patent changes the fundamental torque parameter from negative to positive for DCT vehicles, which simplifies the control logic by eliminating the need for complex release condition differentiation. The positive torque characteristic aligns DCT control more closely with automatic transmission behavior, reducing the need for separate release condition logic.
Data Source
AI summary
A method for releasing creep torque control of a vehicle before a stop includes a step of when creep torque is controlled for a shift before a stop of the vehicle, creep torque control is released in consideration of a current shift gear position if an actual creep torque value controlled during a shift becomes equal to a target creep torque value.