Transmission Upshift Sequencing Control for Engine Lugging
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Solution Overview
Problem
High multi-speed transmissions face challenges in determining the optimal gear shift strategy to match dynamic driving conditions, leading to potential engine lugging and gearbox busyness, especially as the number of gear ratios increases.
Innovation Solution
A method for controlling transmission upshift sequencing that involves detecting a lift foot gear hold condition, engine speed, and using sensors like accelerator pedal, lateral G force, and brake pedal position sensors to determine sequence timers and gear shifts, ensuring smooth transitions and consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transmission shifts to match pattern gear requirements, then fuel economy and driveability improve, but engine lugging and shift busyness occur when driving conditions change rapidly
Solution Approach 1:
The system performs preliminary detection of lift foot gear hold conditions using sensors (accelerator pedal position sensor, lateral G force sensor, brake pedal position sensor) before the actual gear shift occurs. Sequence timers are started in advance to predict when a gear hold condition will end, allowing the transmission control module to prepare for upcoming shifts and avoid engine lugging by pre-positioning the transmission in the appropriate gear.
2Loss of energy
If the transmission uses more gear ratios (8, 9, 10+ speeds), then fuel economy and driveability improve, but the complexity of choosing the appropriate gear increases significantly
Solution Approach 1:
The gear selection process is segmented into discrete, manageable steps using sequence timers for each potential gear hold condition. Instead of evaluating all possible gear shifts simultaneously, the system divides the decision-making into sequential stages: detecting specific conditions (accelerator pedal tip-in/tip-out, lateral G force, brake application), starting corresponding sequence timers, and executing shifts only when the appropriate timer expires. This segmentation makes high-speed transmission control tractable.
Solution Approach 2:
The system dynamically adapts gear selection based on real-time driving conditions detected by multiple sensors. The sequence timer periods are determined based on current gear and engine speed, allowing the system to adjust shift timing dynamically. This dynamic approach enables the transmission to optimize fuel economy across varying driving conditions without requiring overly complex pre-programmed shift schedules.
3Stability of the object's composition
If the transmission holds lower gear for predetermined time before shifting, then smooth transition is achieved, but delay in responding to power demand changes occurs
Solution Approach 1:
The system starts sequence timers in advance when lift foot gear hold conditions are detected, but does not execute the gear shift immediately upon condition occurrence. Instead, the shift occurs when the sequence timer expires, providing a predetermined delay that ensures smooth transitions. The timer-based approach allows the system to balance smoothness and responsiveness by adjusting timer periods based on current operating conditions.
Data Source
AI summary
A method for transmission upshift sequencing includes detecting a lift foot gear hold condition is met and that a current engine speed is greater than a pattern gear engine speed for the current gear. If these conditions exists then the current gear is held until a first sequence timer expires and then an upshift event occurs to a first gear having an engine speed less than the current engine speed. The first gear is then held until a at least one other sequence timer expires and, thereafter, at least one other gear is selected and held until the engine speed is less than or equal to a pattern gear engine speed.