Adaptive Solenoid Valve Control for Transmission Clutch Wear
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dual-clutch and automated manual transmissions are prone to hysteresis due to higher hydraulic pressures, leading to inaccuracies in clutch control and increased wear, as existing solenoid valve performance varies with temperature and usage, causing mismatch between expected and actual performance.
Innovation Solution
A controller adapts the calibrated flow vs. electrical current characteristic table for the solenoid valve by periodically updating it based on actual performance at different temperatures, using closed-loop position control signals to learn and adjust the solenoid valve's electrical characteristics, ensuring optimal shift control accuracy and reduced clutch wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed calibrated Q vs. I characteristic table is used for the solenoid valve, then the control system is simple to implement, but the shift control accuracy deteriorates due to temperature variations and valve performance drift
Solution Approach 1:
The patent implements adaptive control that dynamically adjusts the Q vs. I characteristic table based on real-time valve performance measurements. The controller periodically updates the calibration data to reflect current valve conditions, transforming the static calibration approach into a dynamic adaptation process that maintains accuracy across varying temperatures and usage conditions
Solution Approach 2:
The system performs self-calibration by automatically measuring its own valve performance and updating its characteristic table without external intervention. The controller executes closed-loop position control to learn the actual electrical characteristics of the valve and adjusts the calibration data autonomously, enabling the system to self-correct performance drift
2Measurement precision
If the Q vs. I characteristic table is updated frequently to maintain accuracy, then shift control accuracy is improved, but the loss of time for calibration updates increases
Solution Approach 1:
The patent implements periodic calibration updates rather than continuous updates. The controller periodically executes closed-loop position control to learn and update the Q vs. I characteristic table at scheduled intervals or under specific conditions, balancing the need for accuracy with the time cost of calibration operations
Solution Approach 2:
The system performs rapid calibration updates during periods when the clutch is not in use, utilizing otherwise idle time for calibration operations. This approach rushes through the calibration process during non-critical periods without impacting shift control accuracy during active operation
3Measurement precision
If aggressive integral control is used to correct steady-state error, then accuracy is improved, but position oscillations increase which degrade control precision
Solution Approach 1:
The patent applies preliminary adjustment to the electrical current axis of the Q vs. I characteristic table based on learned zero-flow conditions. By pre-adjusting the calibration data to account for steady-state errors, the system corrects accuracy issues before they manifest as oscillations during normal operation
Solution Approach 2:
The system changes the electrical current parameter in the characteristic table based on learned performance data. By adjusting the current axis to match actual valve characteristics, the system achieves accurate control without requiring aggressive integral control actions that would cause oscillations
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 adaptive approach improves shift control accuracy and reduces clutch wear by aligning the solenoid valve's performance with the calibrated table, minimizing steady-state errors and position oscillations, thereby enhancing the precision and longevity of clutch operations.
Implementation Method 1
a flow control solenoid valve (25)... this valve is a flow control variable force solenoid (VFS) valve
Implementation Method 2
clutch pistons, which are actuated using hydraulic fluid circulated at relatively low pressures
Data Source
AI summary
A vehicle includes an engine, a transmission, and a controller which executes a method. The transmission includes a clutch having an actuator which applies the clutch using position-based control logic. The transmission also includes a fluid pump and a variable-force or other solenoid valve positioned downstream of the pump and upstream of the clutch. The valve outputs a flow rate (Q) for a corresponding solenoid control current (I). The controller adapts a calibrated Q vs. I characteristic table of the valve for different transmission temperatures by applying closed-loop position control signals to the actuator at the different transmission temperatures and recording a null point(s) describing the corresponding solenoid control current (I) at a zero flow rate condition. The controller calculates an offset value for solenoid control current (I) using the recorded null point(s), applies the offset value to the characteristic table, and controls the clutch using the adapted characteristic table.