Powertrain Shift Point Adaptation for WOT Upshift Timing
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Solution Overview
Problem
Green transmissions with little adaptive pressure control learning experience long hydraulic delay times when engaging and disengaging clutches during wide-open throttle events, leading to engine speed reaching the hard fuel cutoff speed, which affects acceleration and shift feel.
Innovation Solution
A method is implemented where the controller programs initial maximum engine speeds for each gear to ensure upshifts occur before reaching the hard fuel cutoff speed, incrementally increasing these speeds after qualifying high-torque events, while restricting maximum allowed engine speed deltas to balance drivability and peak power output, and adapts hydraulic pressure to drive clutch engagement times toward desired values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial shift points are set conservatively to ensure upshifts occur before hard fuel cutoff speed, then reliability is improved, but productivity deteriorates due to restricted peak power output
Solution Approach 1:
The system dynamically adapts shift points from conservative initial values to aggressive mature values based on accumulated operational data. The controller learns and adjusts shift points incrementally over WOT events, transitioning from a static conservative setting to a dynamic adaptive system that optimizes for peak power while maintaining reliability
Solution Approach 2:
The transmission system performs self-learning and self-adjustment by automatically adapting shift points based on its own operational history. The controller monitors WOT events and autonomously modifies shift points without external intervention, enabling the system to serve itself in optimizing performance
2Device complexity
If adaptive pressure control learning is limited in green transmissions, then device complexity is reduced, but loss of time increases due to long hydraulic delay times
Solution Approach 1:
The system performs preliminary adaptive pressure control adjustments during WOT events to pre-condition the hydraulic system for optimal clutch engagement. By proactively learning and adjusting pressure profiles during high-torque events, the system reduces subsequent hydraulic delay times without requiring complex adaptive mechanisms in normal operation
Solution Approach 2:
The adaptive pressure control learning occurs periodically during qualifying WOT events rather than continuously. This periodic action allows the system to accumulate learning data and adjust hydraulic pressure profiles at appropriate intervals, reducing hydraulic delay times through rhythmic optimization cycles
3Productivity
If shift points are increased to achieve peak power output, then productivity is improved, but stability deteriorates due to risk of reaching hard fuel cutoff speed
Solution Approach 1:
The system implements feedback control by monitoring engine speed, torque, and shift timing during WOT events. The controller uses this feedback to incrementally adjust shift points, comparing actual performance against targets and making corrective adaptations to maintain stability while pursuing peak power output
Solution Approach 2:
The system changes operational parameters incrementally by adjusting shift points in small steps during WOT events. Rather than making large abrupt changes, the controller modifies shift points gradually based on learned patterns, maintaining engine speed stability while progressively optimizing for peak power
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 method ensures upshifts occur before reaching the hard fuel cutoff speed, achieving peak power while maintaining drivability, by incrementally adapting shift points and hydraulic pressures, thereby improving acceleration and shift feel over time.
Implementation Method 1
The controller is further programmed to adapt the shift points by increasing the shift points over the series of the wide-open throttle events from initial values to mature values in response to adjustments in the hydraulic pressure
Implementation Method 2
Vehicle transmissions may include hydraulic systems that utilize pressurized hydraulic fluid to engage/disengage various clutches within the transmission
Data Source
AI summary
A vehicle includes an engine, a transmission, and a controller. The engine is configured to generate power to propel the vehicle. The transmission has gears and clutches configured to shift between the gears. The controller is programmed to operate the clutches during wide-open throttle events to upshift the gears at shift points corresponding to engine speeds. The controller is further programmed to adapt the shift points by increasing the shift points over a series of the wide-open throttle events from initial values to mature values.