eLSD Clutch Pressure Control Under Temperature and Viscosity Changes
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Solution Overview
Problem
Existing clutch pressure control systems for electronically controlled limited slip differentials (eLSD) face challenges in accurately regulating clutch pressure due to nonlinearities and time-changing system parameters such as fluid viscosity and degradation, which are not well accounted for in prior control designs.
Innovation Solution
A method for controlling clutch pressure in eLSD that includes a hydraulic control circuit with a processor, memory, and control instructions for implementing PID and sliding mode calculations, along with linear quadratic regulator (LQR) calculations, to generate pressure control valve commands and motor speed control commands, ensuring accurate and adaptive control of clutch torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prior control designs are used for clutch pressure regulation, then the control system is simpler, but the accuracy of clutch pressure regulation deteriorates due to unaccounted nonlinearities and time-changing parameters
Solution Approach 1:
The patent applies parameter changes by implementing adaptive control that dynamically adjusts control parameters based on detected temperature and pressure conditions. The controller modifies PID gains and sliding mode control parameters in real-time to account for fluid viscosity changes and system nonlinearities, thereby maintaining accurate clutch pressure regulation despite varying operating conditions.
Solution Approach 2:
The patent employs feedback mechanisms by continuously detecting actual clutch pressure and temperature, then using this information to adjust control commands. The closed-loop control system compares target pressure with actual pressure and dynamically modifies valve control signals to compensate for nonlinearities and time-changing parameters, resolving the contradiction between control accuracy and system complexity.
2Reliability
If adaptive control accounting for temperature and viscosity changes is implemented, then the robustness of clutch torque control improves, but the device complexity increases
Solution Approach 1:
The control system applies self-service by automatically detecting temperature and pressure conditions and autonomously adjusting control parameters without external intervention. The system monitors fluid temperature, estimates viscosity changes, and dynamically modifies control commands to maintain optimal clutch torque transfer, thereby improving robustness while managing complexity through automated adaptation.
Solution Approach 2:
The patent implements dynamics by transitioning from static control parameters to dynamic, adaptive parameters that change with operating conditions. The controller continuously adjusts PID gains and sliding mode parameters based on real-time temperature and pressure feedback, enabling the system to adapt to viscosity changes and nonlinearities, thus improving reliability while accepting controlled complexity.
3Adaptability or versatility
If multiple control calculations (PID, sliding mode, LQR) are implemented, then the adaptability to different operating conditions improves, but the computational complexity and processing time increase
Solution Approach 1:
The patent applies segmentation by dividing the control algorithm into distinct functional modules: PID control for baseline pressure regulation, sliding mode control for handling nonlinearities and disturbances, and LQR for optimal torque management. Each module processes specific aspects of control, allowing the system to adapt to different operating conditions through coordinated operation of segmented control functions.
Solution Approach 2:
The control system implements universality by designing a multi-functional controller that performs PID regulation, sliding mode adaptation, and LQR optimization within a single integrated system. This universal controller handles various operating conditions (different temperatures, pressures, and torque requirements) through multiple control strategies, achieving high adaptability while consolidating complexity into one control unit.
Data Source
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AI summary
A clutch system comprises a hydraulic control circuit for controlling a hydraulic system. The hydraulic control circuit comprises processor-executable control instructions to perform a method for controlling hydraulic pressure. The method comprises receiving a target hydraulic pressure. The method generates and outputs pressure control valve commands based on a detected current hydraulic pressure, a detected temperature, and the target hydraulic pressure by implementing proportional integral derivative (PID) calculations and sliding mode calculations while carrying out a closed loop pressure control. The method converts the target hydraulic pressure into motor speed control commands and into motor direct current commands by implementing a linear quadratic regulator (LQR) calculation while carrying out a closed loop speed control. The method controls the electric motor using the motor direct current commands. And, the method controls the pressure control valve by using the pressure control valve commands.