Hysteresis Interpolation for Solenoid Control Current in Transmission Clutch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for controlling solenoid current in hydraulic fluid systems for automatic transmissions face inaccuracies due to multi-gain characteristics and variance in pressure output when transitioning between 'up' and 'down' control pressure directions, leading to undesirable clutch pressure variations.
Innovation Solution
A method employing hysteresis interpolation between up and down pressure-current (P-I) tables to determine the required solenoid control current, accounting for the direction of pressure change and gear state, ensuring accurate clutch pressure control by interpolating between current values from both tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate up and down P-I tables are used for solenoid current determination, then direction-specific pressure control is achieved, but variance and inaccuracy occur when operating under different conditions than table capture conditions
Solution Approach 1:
The patent merges the separate up and down P-I tables into a unified hysteresis interpolation model that combines data from both directions. This integration allows the system to leverage information from both increasing and decreasing pressure transitions, creating a more robust and consistent control approach that reduces variance when operating under different conditions than the original table capture conditions.
Solution Approach 2:
The patent pre-captures P-I characteristic data for both up and down directions during system calibration or initialization. By performing this data collection in advance and storing it in lookup tables, the system prepares comprehensive reference information that can be quickly accessed and interpolated during real-time operation, eliminating the need for real-time measurements and ensuring consistent accuracy across varying operating conditions.
2Device complexity
If linear solenoid control is used with single P-I table, then system simplicity is maintained, but multi-gain characteristics cause undesirable pressure variations
Solution Approach 1:
The patent segments the P-I characteristic data into separate up and down direction tables, capturing the multi-gain characteristics of the linear solenoid. By dividing the control data structure into direction-specific segments, the system can account for the different pressure responses during increasing and decreasing current transitions, thereby eliminating undesirable pressure variations while maintaining the simplicity of linear solenoid hardware.
Solution Approach 2:
The patent implements dynamic selection and interpolation between up and down P-I tables based on the current transition direction. This dynamic approach allows the control system to adaptively choose the appropriate characteristic curve and interpolate between current values from both tables, providing accurate pressure control that responds to the real-time direction of current change while preserving the simplicity of the linear solenoid device.
3Device complexity
If interpolation is performed within a single P-I table, then current determination is simplified, but accuracy deteriorates due to not accounting for hysteresis effects
Solution Approach 1:
The patent adds a directional dimension to the current determination process by maintaining separate up and down P-I tables. Instead of performing one-dimensional interpolation within a single table, the system now operates in two dimensions by selecting and interpolating between appropriate tables based on current transition direction. This dimensional expansion captures hysteresis effects and significantly improves current determination accuracy while adding minimal computational complexity.
Solution Approach 2:
The patent uses hysteresis interpolation as an intermediary computational process that bridges the gap between simple single-table lookup and complex real-time measurement. By implementing interpolation logic that considers both up and down characteristic curves, the system acts as a mediator that translates desired pressure values into accurate current commands while accounting for hysteresis, achieving high precision without requiring complex hardware or real-time sensing.
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 enhances accuracy in clutch pressure control by minimizing variance and improving shift performance by accurately determining solenoid control current based on gear state and pressure direction, resulting in more precise clutch engagement and disengagement.
Implementation Method 1
a solenoid having an outlet providing fluid at a pressure variable in accordance with a control current signal
Data Source
AI summary
A transmission control arrangement controls the generation of a required solenoid control current that is provided to an electro-hydraulic pressure control module to ultimately control clutch pressure. The module includes a linear solenoid, which has an up direction pressure-current (P-I) data table and a down direction pressure-current (P-I) data table associated therewith. For large pressure increase change requests the up P-I table is used. For large pressure decrease change requests the down P-I table is used. An interpolation process uses current values taken from both the up and down P-I data tables for pressure change requests that are neither large increases nor large decreases. The control arrangement also includes a variable gain feature that changes the gain in dependence on the gear state of the transmission.