Clutch Slipping Point Detection Under Input Shaft Drag
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Solution Overview
Problem
Existing methods for estimating the clutch slipping point position in gearboxes, particularly in automated mechanical transmissions, are not reliable due to clutch drag torque issues, which can cause the input shaft to rotate even when fully disengaged, making it difficult to accurately determine the slipping point.
Innovation Solution
A method involving the application of a braking means with a predetermined brake torque to prevent input shaft rotation when fully disengaged, followed by moving the clutch towards an engaged position and registering the clutch position when a specific rotational speed is reached, using clutch transfer characteristics to define the slipping point position, and optionally verifying with acceleration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clutch transfer characteristics are used to estimate slipping point position, then measurement precision is improved, but device complexity increases due to additional braking means and control mechanisms
Solution Approach 1:
A braking means is introduced as an intermediary device to temporarily hold the input shaft, creating a controlled condition for measuring clutch drag torque. This mediator enables precise measurement of the clutch slipping point position by isolating the drag torque effect from other rotational influences on the input shaft.
2Reliability
If clutch drag torque is not compensated, then device complexity is reduced, but reliability deteriorates due to inaccurate slipping point detection
Solution Approach 1:
The braking means is activated before the clutch engagement measurement to pre-establish a stationary condition for the input shaft. This preliminary action ensures that any subsequent rotation is solely due to clutch drag torque, enabling reliable detection of the clutch slipping point position without interference from initial shaft motion.
Solution Approach 2:
The system continuously monitors input shaft rotation and uses this feedback to determine when the shaft has started rotating, indicating the clutch slipping point. The control unit processes the rotation signal and uses it to identify the precise moment when drag torque overcomes the braking force, providing reliable slipping point detection.
3Measurement precision
If input shaft rotation is allowed during clutch engagement, then ease of operation is improved, but measurement precision deteriorates due to synchronization with engine
Solution Approach 1:
The braking means is applied periodically during the clutch engagement process - activated before measurement, released during engagement, and reapplied when needed. This periodic braking creates distinct measurement phases separated from engagement phases, allowing precise slipping point detection during braking periods while maintaining smooth engagement during release periods.
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 provides a more accurate and controlled estimation of the clutch slipping point position, ensuring the input shaft does not rotate due to minor drag torque, thereby improving reliability and precision in clutch control.
Implementation Method 1
applying the braking means with a predetermined brake torque and so that the input shaft is not rotating
Implementation Method 2
The clutch slipping point position is typically the clutch position where a small defined torque is transferred
Data Source
AI summary
The present disclosure relates to a method for defining a clutch slipping point position (Xsp) of a clutch in a gearbox comprising an input shaft arranged to be braked by a braking means. The method includes determining if the clutch is dragging when the clutch is fully disengaged. The method includes when it is determined that the clutch is dragging, applying the braking means with a predetermined brake torque (Tb) and so that the input shaft is not rotating; and thereafter: moving the clutch from the fully disengaged position towards an engaged position; determining when the input shaft starts to rotate with a predetermined rotation value indicative of a rotational speed of the input shaft; registering a clutch position (Xb) in which the clutch is positioned when the predetermined rotation value is reached; using a clutch transfer characteristics of the clutch, Tb, and Xb to define the clutch slipping point position (Xsp).