Off-Going Clutch Torque Adaptation for Transmission Upshifts
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Solution Overview
Problem
Existing automatic transmission systems face challenges in smoothly transitioning between gear ratios due to discrepancies between actual and target initiation times and flare times during upshifts, leading to inefficiencies and potential damage from early or late flares.
Innovation Solution
A controller-adjusted torque strategy for off-going clutches during upshifts, where the torque of the off-going clutch is adjusted based on the difference between actual and target initiation times and flare times, using an adaptation timer to calculate errors and adapt the torque capacity to prevent undesired flares.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque transfer from off-going to oncoming clutch is not precisely controlled, then the gear shift may be incomplete or damaged, but the initiation time and flare time cannot be accurately controlled
Solution Approach 1:
The controller monitors actual initiation time and flare time during upshift, compares them with target values, and adjusts off-going clutch torque capacity in subsequent upshifts based on the timing errors. This closed-loop feedback mechanism progressively refines timing accuracy while ensuring reliable gear shift completion.
Solution Approach 2:
The controller pre-adjusts the off-going clutch torque capacity before the upshift based on predicted timing requirements. By proactively modifying torque capacity in advance, the system prepares the clutch to achieve both accurate timing and reliable shift completion without waiting for timing errors to occur.
2Reliability
If the off-going clutch torque capacity is increased to prevent early flare, then the flare time can be delayed to target time, but the torque transfer may cause late flare or shift shock
Solution Approach 1:
The off-going clutch torque capacity is dynamically adjusted based on real-time monitoring of initiation time and flare time. Rather than using a fixed high torque capacity, the system adaptively modifies torque capacity in subsequent upshifts to match actual timing performance, preventing both early and late flare while reducing shift shock.
Solution Approach 2:
The controller changes the torque capacity parameter of the off-going clutch based on timing errors from previous upshifts. By adjusting this critical parameter in response to measured performance, the system optimizes flare timing control while avoiding the harmful effects of excessive torque capacity.
3Productivity
If the transmission uses traditional fixed torque transfer strategy, then the control system is simple, but the gear shift efficiency is reduced due to timing discrepancies
Solution Approach 1:
The controller implements feedback by monitoring initiation time and flare time, comparing them with target values, and adjusting off-going clutch torque capacity in subsequent upshifts. This feedback loop improves gear shift efficiency by eliminating timing discrepancies while adding only moderate control complexity through software-based adaptation.
Solution Approach 2:
The transmission control system performs self-adjustment by automatically modifying off-going clutch torque capacity based on its own measured performance. The system serves itself by using its own timing data to optimize future upshifts, improving efficiency without requiring external intervention or complex additional hardware.
Data Source
AI summary
A vehicle includes a transmission and a controller. The transmission has clutches and multiple speed ratios that are established during gear upshifts upon torque being transferred from off-going to oncoming clutches. The controller is programmed to, in response to a difference between actual and target times of a desired flare at a transmission input exceeding a threshold during an upshift, adjust the torque of the off-going clutch during a torque transfer phase of a subsequent upshift based on the difference.