Dual-Clutch Transmission Synchronization Under Clutch Drag Torque
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Solution Overview
Problem
Current vehicle drivetrains experience prolonged synchronization times during gear changes due to clutch drag torque, and existing closed-loop control routines are slow and inadequate for reducing these times.
Innovation Solution
A method that adjusts deceleration torque based on actual vehicle speed and accelerator pedal position, using feed-forward compensation to calculate and manage clutch drag torque, allowing for quicker synchronization by adjusting the position of couplings between input and output shafts in a dual clutch transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If closed-loop control routine is used to account for clutch drag torque, then synchronization time is reduced, but the control routine is relatively slow and synchronization time remains prolonged
Solution Approach 1:
The system performs preliminary action by pre-calculating and storing clutch drag torque values in lookup tables before gear changes occur. The controller accesses these pre-stored values during the gear change event, eliminating the need for slow real-time calculations and enabling faster synchronization response.
Solution Approach 2:
The patent replaces the slow closed-loop control routine with a feed-forward control approach using pre-calculated lookup tables. This substitution of control methodology allows the system to anticipate and compensate for clutch drag torque effects before they occur, significantly reducing synchronization time.
2Ease of operation
If deceleration torque is adjusted based on vehicle speed and accelerator pedal position, then gear shift smoothness is improved, but control complexity increases
Solution Approach 1:
The system uses lookup tables that contain pre-calculated deceleration torque values based on vehicle speed and accelerator pedal position. Instead of performing complex real-time calculations, the controller copies the appropriate torque value from the lookup table, simplifying the control process while maintaining smooth gear shifts.
Solution Approach 2:
The deceleration torque values are pre-calculated and stored in lookup tables before operation. During gear changes, the controller simply retrieves the appropriate value based on current vehicle conditions, avoiding complex real-time computations while achieving smooth torque transitions.
Data Source
AI summary
Methods and systems are provided for a powertrain. In one example, a method for a powertrain includes adjusting a coupling between a synchronization shaft and one or more of an input shaft and an output shaft in response to a clutch drag torque. The adjusting is based on speeds of one or more of the input shaft, the synchronization shaft, and the output shaft.