Clutch Torque Characterization for Consistent Gearbox Shifting
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Solution Overview
Problem
The inconsistency in clutch actuator position where torque transfer begins across different vehicles leads to variations in shifting sequences and clutch wear, necessitating a method to determine the 'kiss' position for optimal clutch operation.
Innovation Solution
Adjusting the relationship between the clutch actuator position and torque capacity in response to the electric machine's torque output, using a predetermined rate to identify the clutch actuator position at which torque transfer ceases, thereby determining the 'kiss' position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed clutch actuator position is used for torque transfer initiation, then the control system is simple, but the shifting sequence varies across vehicles and clutch wear increases
Solution Approach 1:
The system performs preliminary characterization of the clutch actuator position during manufacturing or initial operation to determine the specific 'kiss' position for each vehicle. This pre-determined position is stored and used during normal operation to ensure consistent shifting sequences across all vehicles, eliminating the need for complex real-time adjustments while maintaining reliability
Solution Approach 2:
The invention changes the parameter of clutch actuator position from a fixed universal value to a vehicle-specific calibrated value. By adjusting the actuator position parameter based on individual vehicle characteristics (such as variations in clutch plate thickness and actuator geometry), the system achieves consistent torque transfer initiation across different vehicles without requiring complex control algorithms
2Reliability
If the clutch actuator position is not precisely determined, then the system is simpler to manufacture, but clutch wear increases due to inconsistent engagement
Solution Approach 1:
The system uses the electric machine's own torque output as a sensor to detect when the clutch begins to transfer torque. During a characterization routine, the electric machine operates in regeneration mode and the control system monitors when torque generation ceases, which indicates the clutch has fully disengaged. This self-detection method eliminates the need for external sensors or complex manufacturing precision, as the system characterizes itself using its own operational parameters
Solution Approach 2:
The control system implements a feedback mechanism where the electric machine's torque output is continuously monitored during clutch operation. When the torque output drops below a threshold, the system identifies this as the point where the clutch has disengaged, providing feedback information that is used to calculate and store the precise 'kiss' position for future operations, thereby reducing clutch wear through precise control
3Productivity
If a predetermined clutch opening rate is used, then the control is simpler, but the shifting sequence duration varies across vehicles
Solution Approach 1:
The system performs preliminary characterization to determine the vehicle-specific clutch behavior parameters, including the relationship between actuator position and torque transfer. This pre-determined information is stored and used to optimize the shifting sequence timing for each vehicle, allowing the control system to execute shifts more efficiently without requiring complex real-time adjustments during the actual shifting operation
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 improves gear shifting consistency and compensates for variations in clutches and actuators across different vehicles, reducing clutch wear and optimizing shifting sequences.
Implementation Method 1
the electric machine may continue to generate charge as long as torque is supplied to the electric machine via the clutch and the vehicle's wheels
Data Source
AI summary
Methods and systems for operating a clutch of an axle are provided. In one example, the clutch may be characterized in static or dynamic conditions. The clutch characterization may be a basis for subsequently operating the clutch during gearbox shifting. In particular, an amount of torque that is transferred via the clutch may be controlled or adjusted according to the clutch characterization.