Adaptive Closed Throttle Downshift Control for Automatic Transmissions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automatic transmission systems face challenges in maintaining high-quality closed throttle downshifts due to manufacturing tolerances, wear, and variations in oil quality and temperature, leading to shift quality degradation.
Innovation Solution
A method and apparatus for adaptively controlling closed throttle downshifts by monitoring transmission characteristics such as input speed, output speed, and shift duration, diagnosing aberrations, and making necessary adjustments to shift control parameters to correct deviations, including off-going clutch pressure, on-coming clutch pressure, and clutch volume adaptive parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If clutch-to-clutch shifting is used to perform downshifts, then shift speed and transmission ratio change are improved, but shift quality degrades due to manufacturing tolerances, wear, and variations in oil quality and temperature
Solution Approach 1:
The patent implements adaptive control that dynamically adjusts shift parameters (clutch apply pressure, fill time, release pressure) based on real-time monitoring of transmission conditions including oil temperature, clutch wear indicators, and actual shift performance. This allows the system to optimize shift quality for each specific operating condition rather than using fixed parameters, thereby maintaining high shift quality despite manufacturing tolerances and wear over time
Solution Approach 2:
The system incorporates feedback mechanisms that monitor transmission characteristics during and after shifts, including input/output shaft speeds, clutch engagement status, and shift duration. This feedback is used to continuously refine shift control parameters, compensating for manufacturing variations and wear effects. The adaptive controller learns from past shift performance to optimize future shift commands, thereby maintaining reliable shift quality across the transmission's operational lifecycle
2Reliability
If precise timing is used in clutch-to-clutch shifts, then shift quality is improved, but control complexity increases due to the need for cooperative operation of multiple functions
Solution Approach 1:
The patent combines multiple shift control functions (clutch pressure control, timing control, fluid pressure management) into a single adaptive control module that coordinates all these functions simultaneously. Rather than managing each function separately with independent control systems, the unified controller integrates timing, pressure, and flow control into one coordinated system, reducing overall control complexity while maintaining precise timing requirements for high shift quality
Solution Approach 2:
The system uses parameter-based control where shift quality is achieved by adjusting key parameters (fill time, apply pressure, release pressure) rather than complex timing sequences. The adaptive controller modifies these parameters based on monitored transmission conditions, simplifying the control approach while maintaining precise coordination of multiple functions. This parameter-focused approach reduces control complexity compared to event-driven timing control
Data Source
AI summary
The present invention provides a method and apparatus for adaptively controlling a closed throttle downshift in an automatic transmission wherein a transmission aberration during a shift is diagnosed and corrected during subsequent closed throttle downshifts. The invention is carried out by monitoring transmission characteristics including input speed, output speed and shift duration during a closed throttle downshift, and identifying departures from acceptable patterns. Each type of departure calls for a particular remedy, and a suitable adjustment is calculated based on the times and/or the commanded pressures at certain times, the adjustment being implemented by changing one or more initial conditions for the next shift of the same type. The adjustments may have to be large to make a full or significant partial correction at the next shift. Conversely small increments may be necessary to avoid over-correction.