Transmission Shift Element Control Using Unfiltered Speed Signals
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Solution Overview
Problem
Existing methods for actuating form-locking shift elements in transmissions fail to account for sudden changes in rotational speed, leading to potential damage when engaging or disengaging gears, as they rely on filtered signals that do not adequately capture these changes within the specified rotational speed window.
Innovation Solution
The method verifies engagement feasibility using unfiltered rotational speed signals, triggering countermeasures if sudden changes occur, such as blocking actuation or shifting to neutral to prevent damage, and utilizes a ring buffer to determine signal differences for reliable assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filtered signals are used to determine actuation time, then the control is stable and smooth, but sudden changes in rotational speed are not detected, leading to potential damage
Solution Approach 1:
The patent segments the signal processing into two parallel paths: one using filtered signals for stable actuation time determination, and another using unfiltered signals for sudden change detection. This segmentation allows both stability and responsiveness to be achieved simultaneously without compromising either aspect.
2Reliability
If unfiltered signals are used for verification, then sudden changes are detected, but the control becomes more complex and responsive time is reduced
Solution Approach 1:
The patent introduces an intermediary verification step where unfiltered signals are used specifically to check whether sudden changes have occurred, without requiring the entire control system to process unfiltered signals continuously. This intermediary check adds minimal complexity while providing the necessary safety verification.
3Reliability
If actuation is blocked due to sudden changes, then component damage is prevented, but gearshift execution is delayed
Solution Approach 1:
The patent applies preliminary anti-action by blocking the actuation only when sudden changes are detected that would cause damage, while allowing normal actuation to proceed without interruption when no such changes occur. This selective blocking prevents damage while minimizing impact on normal gearshift execution time.
Data Source
AI summary
A method of actuating a form-locking shift element of a transmission. To shift from a current gear to a target gear, an actuation time is determined for the locking shift element to be engaged during a gear shift depending on a reaction time of the assemblies participating during actuation of the locking shift element, an engaging time of the locking shift element, and at least one filtered signal such that the locking shift element is engaged within a specified rotational speed window encompassing a specified differential rotational speed. It is verified whether the locking shift element can be engaged within the specified rotational speed window depending on at least one unfiltered signal, and, if the locking shift element can be engaged within the specified rotational speed window, the actuation is unaffected; conversely, if the locking shift element cannot be engaged within the specified rotational speed window, the actuation is affected.