Adaptive Clutch Torque Control via Lubrication-Dependent Transfer Functions
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Solution Overview
Problem
Current vehicle control systems face challenges in accurately controlling the torque of disconnect clutches during engine starts, particularly under varying lubrication conditions, which affects drivability and clutch control robustness, due to the complexity of clutch transfer functions and the need for specialized torque sensing devices.
Innovation Solution
The implementation of an adaptive control system that utilizes an inertial measurement unit (IMU) signal to identify and construct multiple transfer functions for the disconnect clutch, allowing for precise torque control during engine starts by determining the slipping condition of the clutch and adjusting the clutch actuator pressure based on mapped relationships, eliminating the need for specialized torque sensing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single clutch transfer function is used for all lubrication conditions, then the device complexity is reduced, but the torque control precision deteriorates under varying lubrication conditions
Solution Approach 1:
The patent segments the clutch transfer function into multiple distinct functions, each corresponding to a specific lubrication condition (hydrodynamic, mixed, boundary). The controller identifies the current lubrication condition and selects the appropriate transfer function, thereby maintaining torque control precision across varying conditions without requiring a single overly complex universal function.
Solution Approach 2:
The system dynamically adapts the clutch transfer function based on real-time lubrication conditions. By continuously monitoring clutch operating parameters and identifying the current lubrication regime, the controller dynamically switches between different transfer functions, enabling the system to respond optimally to changing conditions without fixed complexity.
2Measurement precision
If specialized torque sensing devices are used, then the torque measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The system uses existing sensors and available data (clutch actuator pressure, engine speed, vehicle speed) to indirectly determine clutch torque through the selected transfer function. This self-service approach eliminates the need for specialized torque sensing devices while maintaining sufficient measurement precision for control purposes.
Solution Approach 2:
The patent introduces an intermediary approach by using the identified lubrication condition as a selector to choose from multiple pre-established transfer functions. This intermediary mechanism (condition-based selection) allows the system to achieve accurate torque estimation without direct torque sensing, bridging the gap between available measurements and required control information.
3Adaptability or versatility
If multiple transfer functions are constructed for different slipping conditions, then the torque control adaptability is improved, but the device complexity increases
Solution Approach 1:
The system performs preliminary action by pre-establishing multiple transfer functions corresponding to different lubrication conditions before operation. During runtime, the controller only needs to identify the current condition and select the appropriate pre-prepared function, avoiding the complexity of dynamically generating or managing complex adaptive models while maintaining high adaptability.
Data Source
AI summary
A vehicle includes a transmission, an engine, a clutch, and a controller. The transmission has an input. The engine is configured to generate and deliver torque to the input. The clutch is configured to connect and disconnect the engine from the input, and to crank the engine during an engine start. The controller is programmed to, in response to a command to adjust a torque of the clutch during an engine start and a presence of first condition of the clutch, drive a clutch actuator pressure to a first desired value based on a first transfer function. The controller is further programmed to, in response to a command to adjust the torque of the clutch during the engine start and a presence of a second condition of the clutch, drive the clutch actuator pressure to a second desired value based on a second transfer function.