Powertrain Torque Control for Flare-Free Transmission Shifts
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Solution Overview
Problem
Existing vehicle powertrain control systems face challenges in smoothly shifting transmission gears while managing engine torque, particularly during flare conditions, which can lead to inefficiencies and potential engine misfires due to inadequate torque regulation.
Innovation Solution
A controller is programmed to adjust engine torque by retarding the spark and shutting down cylinders based on a flare at the transmission input, with specific torque thresholds to manage power transfer efficiently during gear shifts, ensuring all cylinders operate within safe limits during high torque demands and shutting down cylinders during lower demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If engine torque is reduced during transmission shift to compensate for flare, then gear shift smoothness is improved, but engine power output is reduced
Solution Approach 1:
The controller retards engine spark timing before the transmission shift occurs to proactively reduce engine torque. This preliminary torque reduction prevents flare at the transmission input during the shift, ensuring smooth gear transitions while maintaining engine operation. The spark retard is applied in advance based on predicted shift timing and flare compensation requirements.
Solution Approach 2:
The controller selectively shuts down one or more engine cylinders during the shift event rather than reducing torque from all cylinders. This partial action approach reduces engine torque sufficiently to compensate for flare while maintaining partial power output from remaining active cylinders, thus balancing shift smoothness with power delivery.
2Stability of the object's composition
If spark is retarded to reduce engine torque during shift, then transmission input flare is reduced, but engine efficiency is reduced
Solution Approach 1:
The controller shuts down specific cylinders during the shift event rather than retarding spark across all cylinders. This selective cylinder shutdown reduces torque from affected cylinders while other cylinders continue operating at efficient spark timing, thereby maintaining overall engine efficiency while still achieving the necessary torque reduction to stabilize transmission input during the shift.
Solution Approach 2:
The controller retards spark timing in advance of the shift event to proactively reduce torque and prevent flare. By applying spark retard before the shift occurs, the system minimizes the duration of inefficient operation, as full efficiency is restored once the shift is complete and normal spark timing is reinstated.
3Power
If all cylinders are maintained during high torque demand, then engine power is maintained, but torque regulation precision is reduced
Solution Approach 1:
The controller divides the engine into multiple independent cylinder groups and selectively shuts down specific cylinders during the shift event. This segmentation allows precise control over torque reduction by targeting only the necessary cylinders, enabling accurate torque regulation to compensate for transmission flare while maintaining power from remaining active cylinders.
Solution Approach 2:
The controller selectively shuts down one or more cylinders rather than all cylinders during the shift. This partial action provides fine-grained torque regulation capability, allowing the system to achieve the precise torque reduction needed for flare compensation while minimizing the impact on overall engine power output.
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 enables smoother gear shifts, reduces engine torque fluctuations, and prevents engine misfires by dynamically adjusting engine operation to match transmission requirements, enhancing overall powertrain efficiency and reliability.
Implementation Method 1
retard an engine spark and maintain operation of all cylinders of the engine to reduce the torque of the engine during the shift
Implementation Method 2
shutdown at least one cylinder of the engine to reduce the torque of the engine during the shift
Data Source
AI summary
A vehicle includes an engine, a transmission, and a controller. The transmission is configured to transfer power from the engine to at least one drive wheel to propel the vehicle. The controller programmed to, in response to a command to shift the transmission, reduce a torque of the engine from a desired engine torque to a reduced value based on a flare at an input to the transmission during the shift. The controller is further programmed to, in response to the reduced value exceeding a threshold, retard an engine spark and maintain operation of all cylinders of the engine to reduce the torque of the engine during the shift. The controller is further programmed to, in response to the reduced value being less than the threshold, retard the engine spark and shutdown at least one cylinder of the engine to reduce the torque of the engine during the shift.