Dual Clutch Transmission Launch Control Torque Compensation
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Solution Overview
Problem
Dual clutch transmissions, especially dry DCTs, experience temperature-related performance variations leading to inconsistent vehicle launches due to lack of cooling at friction interfaces, resulting in a less smooth and less consistent feel compared to wet DCTs.
Innovation Solution
A launch control method using a transmission control module (TCM) and engine control module (ECM) that calculates and adjusts the clutch torque by comparing actual engine torque with inertial torque, performing closed-loop control to synchronize clutch position, thereby modifying a torque-to-position table to optimize clutch engagement for smooth launches in both wet and dry DCTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dry dual clutch transmission is used, then device complexity is reduced and manufacturing cost is lowered, but temperature-related performance variation increases leading to inconsistent vehicle launches
Solution Approach 1:
The control module continuously monitors actual engine torque and compares it with calculated clutch torque, using the difference to dynamically adjust clutch position commands in real-time, creating a closed-loop feedback system that compensates for temperature variations
Solution Approach 2:
The system dynamically modifies the torque-to-position mapping parameters based on real-time torque differences, adjusting the clutch position commands to account for changing friction characteristics due to temperature effects
2Productivity
If clutch torque is increased for faster acceleration, then productivity is improved, but launch smoothness deteriorates due to excessive torque transfer
Solution Approach 1:
The system dynamically adjusts clutch position in real-time based on the difference between actual and calculated torque, continuously optimizing the torque transfer rate to balance acceleration speed and launch smoothness throughout the launch process
Solution Approach 2:
By continuously monitoring torque differences and adjusting clutch position commands accordingly, the system prevents excessive torque transfer that would cause harsh launches while maintaining high acceleration capability
Data Source
AI summary
A vehicle includes an engine, an engine control module (ECM), and a dual clutch transmission (DCT) assembly. The DCT assembly has first and second input clutches, first and second gear sets selectively connected to the engine via the respective first and second input clutches, and a transmission control module (TCM). In executing a launch control method, the TCM receives a launch request, receives an actual engine torque, and determines the inertia and acceleration of the engine. The TCM then calculates a clutch torque for the particular input clutch used for vehicle launch as a function of the actual engine torque and the product of the inertia and the acceleration, compares the calculated clutch torque to the commanded clutch torque, modifies a torque-to-position (TTP) table depending on the comparison result, and transmits a clutch position signal to the designated input clutch to command an apply position extracted from the TTP table.