Transmission Control Device Sailing Mode Shift Element Verification
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Solution Overview
Problem
In motor vehicle transmissions with positively locking and frictionally locking shift elements, there is a risk of seizure and damage during gear changes, particularly in sailing mode, where it is crucial to ensure that positively locking shift elements are correctly disengaged to avoid over-determinacy and maintain safety and comfort.
Innovation Solution
A method that checks the rotational speed of the transmission input and output shafts to verify if positively locking shift elements are disengaged during sailing mode adjustments, using defined rotational speed thresholds to determine correct disengagement and prevent potential seizures by initiating alternative measures if faulty disengagement is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a positively locking shift element is opened in sailing mode during adjustment of shift elements, then the transmission can exit sailing mode within the shortest possible time, but there is a risk of seizure and faulty disengagement which can lead to over-determinacy
Solution Approach 1:
The control device monitors the rotational speed of the transmission input shaft and compares it against threshold values to determine whether a positively locking shift element has successfully disengaged. This feedback mechanism allows the system to verify disengagement status in real-time, enabling rapid exit from sailing mode while ensuring reliable operation by detecting and responding to faulty disengagement conditions.
2Reliability
If rotational speed monitoring is implemented to check disengagement of positively locking shift elements, then safety and reliability are improved, but device complexity increases due to additional monitoring requirements
Solution Approach 1:
The control device utilizes existing rotational speed sensor data from the transmission input shaft to monitor disengagement of positively locking shift elements. By leveraging already-available sensor information and processing it through existing control logic, the system achieves reliable fault detection without requiring additional sensors or complex monitoring hardware, thus maintaining simplicity while improving reliability.
Data Source
AI summary
A method for operating a motor vehicle having a transmission (1), the method including closing a first number of shift elements and opening a second number of shift elements in each selected, force locking gear ratio of the transmission (1); closing one shift element less, and therefore opening one shift element more than in a selected, force locking gear ratio when a transmission (1) is not force locking in the sailing mode; adjusting the respectively closed and opened shift elements as a function of at least one operating condition of the motor vehicle in the sailing mode; and checking, at least on the basis of the rotational speed of the transmission input shaft (2), whether a previously closed, positively locking shift element (A, F) to be opened is actually opened in the sailing mode during adjusting of the respectively closed and opened shift elements.