Dual Clutch Transmission Slip Factor Learning
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Solution Overview
Problem
Dual clutch transmissions (DCTs) face challenges in performing gear shifting without a strange feeling due to changes in friction and slip characteristics during torque transfer between clutches, which are difficult to control accurately.
Innovation Solution
A slip factor learning method that determines whether the DCT is up-shifted or down-shifted, compares engine speed and torque to clutch torque, and learns the slip factor based on these comparisons, adjusting clutch torque accordingly to prevent excessive slip and ensure smooth gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the DCT uses a fixed TS curve for clutch control, then the initial gear shifting performance is accurate, but the clutch torque control becomes inaccurate over time due to abrasion, thermal deformation, and mass-production deviation
Solution Approach 1:
The system performs preliminary learning of the TS curve at the initial stage to establish accurate baseline characteristics. This preliminary action creates a reference model that is later continuously refined through operational learning, ensuring both initial accuracy and long-term reliability.
Solution Approach 2:
The system implements continuous feedback mechanisms during gear shifting operations to detect deviations from the expected TS curve. By monitoring actual clutch behavior and comparing it with the learned model, the system dynamically adjusts control parameters to compensate for wear, thermal effects, and manufacturing variations.
2Reliability
If the DCT learns the TS curve to prevent abnormalities, then the transmission system reliability improves, but the friction characteristic and slip characteristic change during gear shifting making it difficult to perform smooth gear shifting
Solution Approach 1:
The system dynamically adapts the TS curve model during operation by continuously learning from actual clutch behavior. This dynamic adjustment allows the system to maintain reliability through accurate modeling while simultaneously optimizing for smooth gear shifting by adapting to changing friction characteristics in real-time.
Solution Approach 2:
The system changes the parameters of the TS curve model based on learned characteristics during gear shifting. By adjusting parameters such as clutch torque, stroke, and slip factor based on actual operational data, the system maintains both reliability and operational smoothness despite variations in friction characteristics.
3Productivity
If the clutch torque is increased to match the engine torque during gear shifting, then the power transmission efficiency improves, but excessive impact occurs when the clutch torque equals or exceeds the normal value
Solution Approach 1:
The system applies partial torque transfer during gear shifting by controlling the clutch torque to be slightly less than the full engine torque. This partial action approach prevents excessive impact while maintaining sufficient power transmission efficiency, avoiding the harmful effects of complete torque matching.
Solution Approach 2:
The system预先 cushions the torque transfer process by gradually increasing clutch torque before reaching the full engine torque level. This prior cushioning prevents impact by smoothly transitioning through the torque transfer phase, ensuring that the clutch torque never abruptly equals or exceeds the normal value.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for accurate clutch torque application during gear shifting, preventing excessive slip and enabling smooth, comfortable gear transitions without a strange feeling.
Implementation Method 1
The slip may occur when coupling and releasing which are two frictional elements during gear shifting are not suitably controlled
Data Source
AI summary
A slip factor learning method of a dual clutch transmission (DCT) may include: determining, by a control unit, whether the DCT is up-shifted or down-shifted; comparing an engine speed to a shift start reference speed, and determining whether the engine speed enters an actual gear shifting period or actual gear shifting is completed, in response to the determined type of the gear shifting; comparing a magnitude of an engine torque to a magnitude of a clutch torque at a point of time that the engine speed enters the actual gear shifting period or the actual gear shifting is completed; and learning a slip factor at the point of time that the engine speed enters the actual gear shifting period or the actual gear shifting is completed, based on the magnitude comparison result between the engine torque and the clutch torque.