Transmission Shift Pressure Mapping for Target Slip Control
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Solution Overview
Problem
Existing methods for implementing gear ratio changes in vehicle transmissions are unreliable due to faulty characteristic maps caused by component tolerances and aging, leading to inconsistent slip states and reduced comfort.
Innovation Solution
Monitor the actual slip at the engaged shift element and compare it with the target slip, adapting the characteristic map based on the deviation to ensure the shift element reaches the desired slip state reliably, using offset values to adjust the shift-element pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a characteristic map is used to determine shift-element pressure for gear ratio changes, then gear shifts can be implemented with defined target slip, but component tolerances and aging cause the characteristic map to become faulty, leading to deviation between actual and target slip
Solution Approach 1:
The patent implements a feedback mechanism by monitoring the actual slip at the shift element during gear ratio changes and comparing it with the target slip. Based on the deviation detected, the characteristic map is adapted to correct future pressure determinations, ensuring continuous improvement of shift accuracy despite component aging and tolerances.
Solution Approach 2:
The patent changes the parameters of the characteristic map based on monitored deviations between actual and target slip. By adjusting the characteristic map parameters according to observed performance, the system adapts to component aging and tolerances, maintaining accurate target slip achievement over time.
2Measurement precision
If the characteristic map is adapted based on slip deviation, then target slip accuracy is improved, but additional monitoring and adaptation mechanisms increase system complexity
Solution Approach 1:
The control unit performs self-adjustment by automatically monitoring slip deviations and adapting its own characteristic map without external intervention. This self-service approach improves measurement precision while minimizing the need for additional external calibration equipment or manual adjustments.
Solution Approach 2:
The system uses feedback from actual slip monitoring to automatically adjust the characteristic map, creating a closed-loop control system that improves precision without requiring complex external calibration mechanisms.
Data Source
AI summary
A method for operating a drive train (1) of a vehicle monitoring the actual slip forming at a particular first shift element of a transmission (5), comparing the actual slip with a target slip, adapting a characteristic map depending on a deviation between the actual slip and the target slip. The characteristic map is used to determine a shift-element pressure for providing the target slip for a particular first shift element in order to implement a gear ratio change.