Dual-Clutch Transmission Control via Interim Slip State
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Solution Overview
Problem
Existing methods for gear changes in dual-clutch transmissions face challenges in reducing power loss and achieving smooth torque transitions without traction interruption, often resulting in shifting jerks due to imprecise clutch control and permanent slipping states.
Innovation Solution
The method involves reducing the clutch pressure to an opening point where torque cannot be transmitted, bringing the clutch into an interim slip state, recording the pressure and torque pair values, and then increasing pressure to cancel the slip state, ensuring precise and up-to-date control for each shifting operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the clutch is operated close to the opening point in a permanent slip state to reduce switching times, then the shifting process is accelerated, but power loss increases due to continuous slipping
Solution Approach 1:
The clutch is brought into an interim slip state before the opening point is reached, allowing precise determination of the pressure-torque relationship in advance. This preliminary action enables accurate prediction of the opening point without requiring continuous slipping, thus reducing power loss while maintaining fast switching.
Solution Approach 2:
The method records the pressure applied and torque transmitted as a pair of values when a predefined slip level is reached. This feedback mechanism allows the control system to use previously determined characteristics to predict and control future clutch behavior, eliminating the need for continuous slip-based operation and reducing power loss.
2Manufacturing precision
If the clutch pressure is reduced to an opening point for precise gear change, then torque transition becomes smooth, but determining the opening point becomes difficult due to constantly changing engine torque
Solution Approach 1:
The system performs preliminary determination of the pressure-torque relationship by bringing the clutch into an interim slip state before the opening point. This advance characterization allows the opening point to be predicted accurately even when engine torque changes constantly, without requiring real-time detection difficulties.
Solution Approach 2:
The clutch system determines its own characteristics by monitoring the relationship between applied pressure and transmitted torque during controlled slip states. This self-characterization enables the system to adapt to changing engine torque conditions without external intervention, maintaining precise opening point determination.
3Ease of operation
If soft opening and closing of separating clutches is used to avoid shifting jerks, then comfort is improved, but shifting time increases
Solution Approach 1:
The clutch is brought into an interim slip state before the opening point to pre-determine the pressure-torque relationship. This allows the control system to execute soft opening/closing sequences with precise timing, achieving both comfort and fast shifting by avoiding unnecessary delays while maintaining gentle torque transition.
Solution Approach 2:
The recorded pressure-torque pairs from interim slip states provide feedback that enables the control system to optimize the opening/closing sequence. This feedback allows precise control of torque transition smoothness while minimizing shifting time, resolving the contradiction between comfort and speed.
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
This approach minimizes power loss by eliminating slip-related losses and allows for harmonious torque transitions during gear changes, optimizing clutch control and reducing shifting time while maintaining comfort.
Implementation Method 1
the torque that can be transmitted by the clutch arrangement is reduced to an opening point at which torque can no longer be transmitted via the clutch arrangement
Data Source
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AI summary
The invention relates to a method for opening a closed clutch assembly (16, 18) of a drive train (10) for a motor vehicle, wherein the clutch assembly (16, 18) is controlled in such a way that the torque that can be transmitted by it is reduced to an opening point at which no more torque can be transmitted via the clutch assembly (16, 18), and wherein, before reaching the opening point, the clutch assembly (16, 18) is brought into an intermediate slip state (Fig. 1).