Transmission Torque Constraint Adjustment for Faster Clutch Offloading
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Solution Overview
Problem
Current shift control systems in transmissions face challenges in reducing shift time while maintaining desired output torque, which affects drivability and fuel economy.
Innovation Solution
A system that includes a shift control module which determines when to offload an off-going clutch quickly by adjusting torque constraints, using a combination of short-term and long-term torque constraints to synchronize and load the oncoming clutch, thereby minimizing shift time and optimizing torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the off-going clutch is offloaded quickly to reduce shift time, then shift time is reduced, but the output torque constraint may be violated
Solution Approach 1:
The system dynamically adjusts the off-going clutch torque constraint range based on the current shift phase and torque requirements. During the torque phase, the constraint range is expanded to allow faster clutch offloading, while automatically restoring the original constraint range when the torque phase ends, thus adapting the control strategy to real-time operational needs
Solution Approach 2:
The invention changes the torque constraint parameter values temporarily during the torque phase. By modifying the off-going clutch torque constraint from its normal range to an expanded range that permits negative torque values, the system enables faster clutch offloading without permanently altering the constraint parameters, thereby resolving the contradiction between speed and reliability
2Speed
If the off-going clutch torque constraint is relaxed to enable faster offloading, then clutch offloading speed is improved, but torque control precision deteriorates
Solution Approach 1:
The system applies partial relaxation of the torque constraint only during the specific torque phase when fast offloading is needed, rather than permanently relaxing the constraint. The constraint range is expanded just enough to permit faster offloading while the control module actively manages torque delivery to maintain acceptable precision, applying excessive action only when necessary
3Productivity
If the torque constraint range is expanded during torque phase, then clutch offloading performance is improved, but system complexity increases
Solution Approach 1:
The control module continuously monitors the shift phase and automatically adjusts the torque constraint range based on feedback from the system state. When the torque phase is detected, the constraint range is expanded; when it ends, the original constraints are restored. This feedback mechanism manages the complexity automatically without requiring complex manual intervention or additional hardware
Data Source
AI summary
A system for a vehicle includes a constraint module that generates a plurality of constraints. An output torque module generates a commanded output torque based on a torque request and the plurality of constraints. A split torque module determines a first torque and a second torque to be applied to a transmission of the vehicle based on the plurality of constraints and the commanded output torque. A first one of the plurality of constraints corresponding to a first clutch is adjusted from a first range of values to a second range of values that is different from the first range of values in response to a command to offload the first clutch.