Dual Clutch Transmission Touch Point Learning via Virtual Input Shaft Speed
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Solution Overview
Problem
Conventional dual clutch transmission (DCT) touch point learning methods are ineffective in high-speed running conditions due to synchronized input shaft behavior of the drive and non-drive shaft, leading to inaccurate torque transfer estimation and potential clutch shock or slip.
Innovation Solution
A method that calculates a virtual input shaft speed using a virtual gear ratio based on vehicle speed and tire diameter, allowing for touch point learning by applying torque to the non-drive shaft to equal engine speed and determining the touch point based on speed differences, thereby correcting clutch position learning amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional touch point learning method is used while gear is in neutral state, then touch point can be learned through change in acceleration of non-drive shaft, but input shaft speed of non-drive shaft cannot be reduced due to drag characteristics while vehicle is running, making the method ineffective in high-speed conditions
Solution Approach 1:
The patent segments the touch point learning process into two distinct methods: conventional acceleration-based learning for low-speed conditions and virtual input shaft speed-based learning for high-speed conditions. This segmentation allows each method to be optimized for its specific operating range, resolving the contradiction between measurement precision and adaptability across different speed conditions
Solution Approach 2:
The patent introduces a virtual input shaft speed as an intermediary parameter to enable touch point learning in high-speed conditions. By calculating the virtual input shaft speed based on vehicle speed and gear ratio, the system can determine touch point without relying on actual non-drive shaft speed reduction, which is prevented by drag characteristics during vehicle operation
2Loss of information
If torque is applied to non-drive shaft to learn touch point, then touch point information can be obtained, but excessive slip or shock may occur in clutch when transfer torque change is not known
Solution Approach 1:
The patent applies preliminary action by gradually and controllably applying torque to the non-drive shaft during touch point learning. The clutch actuator is controlled to move at a predetermined speed while monitoring the difference between virtual input shaft speed and non-drive shaft speed, allowing torque to be applied in a controlled manner that prevents excessive slip or shock while still obtaining touch point information
Solution Approach 2:
The patent implements feedback by continuously monitoring the speed difference between the virtual input shaft and non-drive shaft during torque application. When the speed difference exceeds a predetermined threshold, the system identifies the touch point and adjusts torque application accordingly, preventing excessive slip or shock while ensuring accurate touch point detection
Data Source
AI summary
Provided is a method of learning a touch point of a dual clutch transmission (DCT), and more particularly, to a DCT touch point learning method in which a touch point is learned based on a difference between a virtual input shaft speed and a clutch non-drive shaft input speed using a virtual input shaft reference speed calculated based on the speed of a traveling vehicle. In a traveling situation in which the touch point cannot be learned using the non-drive shaft according to the related art because the input shaft behavior of the non-drive shaft is rotationally synchronized with the input shaft behavior of the drive shaft by drag characteristics of the DCT, a virtual input shaft speed may be calculated, and the touch point of the clutch may be learned using the virtual input shaft speed.