DCT Clutch Temperature Control for Shifting Speed and Heat
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dry clutches in Dual Clutch Transmissions (DCTs) are prone to overheating during continuous creeping, unintended accelerations, and repeated power-on downshifting, leading to reduced durability and potential overheating issues.
Innovation Solution
A shift control method that compares clutch temperature with predetermined reference values, prevents coaxial power-on downshifting when temperatures exceed a first reference value, and reduces shift time and increases shift speed during biaxial full skip shifting when temperatures exceed a second reference value, using a controller to manage clutch torque and synchro-mechanism engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If coaxial power-on downshifting is performed to improve shifting speed and responsiveness, then shifting performance is improved, but clutch temperature increases and overheating occurs
Solution Approach 1:
The controller changes operational parameters based on clutch temperature conditions. When temperature exceeds the first reference value, coaxial power-on downshifting is restricted. When temperature exceeds the second reference value, biaxial full skip downshifting is restricted. This dynamic parameter adjustment resolves the contradiction by adapting shifting behavior to thermal conditions.
Solution Approach 2:
The system dynamically adjusts available shifting modes based on real-time clutch temperature. The controller transitions from allowing all downshift types at low temperature to restricting specific downshift types at elevated temperatures, creating a dynamic response that balances performance and thermal management.
2Reliability
If clutch temperature monitoring and restriction control are implemented to prevent overheating, then clutch durability is improved, but shifting flexibility and driver responsiveness are reduced
Solution Approach 1:
The controller applies different restriction levels to different downshifting scenarios based on local temperature conditions. Coaxial power-on downshifting is restricted at the first temperature threshold, while biaxial full skip downshifting is restricted at the second threshold. This localized quality approach maintains flexibility by allowing different shifting modes under different thermal conditions.
Solution Approach 2:
Instead of completely restricting all downshifting when temperature is high, the system applies partial restrictions based on the severity of temperature elevation. At the first reference value, only coaxial power-on downshifting is restricted. At the second reference value, both coaxial and biaxial downshifting are restricted. This partial action approach preserves necessary shifting flexibility while protecting against overheating.
3Loss of time
If shift time is reduced by increasing shift speed during biaxial full skip shifting, then shifting performance is improved, but clutch load increases and heat generation increases
Solution Approach 1:
The controller takes preliminary anti-action by restricting biaxial full skip downshifting when clutch temperature exceeds the second reference value. This preventive measure avoids the harmful effect of additional heat generation during already hot conditions, while still allowing such shifts when temperature is acceptable.
Data Source
AI summary
A shift control method for a vehicle with a Dual Clutch Transmission (DCT) includes comparing, by a controller, a current clutch temperature with a first predetermined reference value and a second predetermined reference value, the second predetermined reference value being greater than the first reference value, preventing, by the controller, coaxial power-on downshifting when the clutch temperature is greater than the first reference value, and reducing, by the controller, a shift time by preventing coaxial power-on downshifting when the clutch temperature is greater than the second reference value and then increasing a shift speed when biaxial full skip shifting is required.