Dual Torque Shift Strategy for Seamless Transmission Control
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Solution Overview
Problem
Existing transmission control systems face challenges in seamlessly executing multiple torque-controlled shifts without time delays or engine torque disruptions, particularly when a second shift is requested during an ongoing first torque-controlled shift.
Innovation Solution
A dual torque-controlled shift strategy that merges two shift control strategies, allowing for the gradual engagement of new clutches and the release of off-going clutches to ensure smooth transitions between gear ratios without interruptions, by maintaining continuous engine torque and adjusting clutch pressures accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a second torque controlled shift is requested during an ongoing first torque controlled shift, then the transmission can respond to driver demands more quickly, but traditional sequential shift execution causes time delays and engine torque disruptions
Solution Approach 1:
The patent applies preliminary action by staging the second on-coming clutch in advance during the first shift execution. The control pressure for the second on-coming clutch is increased to a staging pressure level before the first shift completes, preparing it for rapid engagement when the second shift is needed, thus eliminating delay when the second shift request occurs
Solution Approach 2:
The patent maintains continuity of useful action by commanding the engine to provide continuous torque throughout the dual shift operation. The torque communication through the first on-coming clutch is continuously increased while the second on-coming clutch is staged and then engaged, ensuring uninterrupted torque flow and eliminating engine torque disruptions between shifts
2Device complexity
If traditional sequential shift control is used, then the control system remains simple, but dual shift execution causes time delays and torque disruptions
Solution Approach 1:
The patent applies segmentation by dividing the dual shift execution into distinct phases: first shift execution phase, transition phase, and second shift execution phase. Each phase has specific clutch control actions (releasing off-going clutches, engaging on-coming clutches at different rates) that can be independently controlled and optimized, allowing complex dual shift operation to be managed through structured segmentation
Solution Approach 2:
The patent uses the first on-coming clutch as an intermediary element that transitions into a holding clutch function. This intermediary clutch maintains torque communication continuity while the second on-coming clutch is engaged, acting as a bridge that ensures smooth transition and prevents torque disruptions during the dual shift operation
Data Source
AI summary
A method of controlling a transmission includes determining if the transmission is currently executing a first torque controlled shift from a first gear ratio to a second gear ratio. A torque controlled shift is defined as a shift control operation in which the speed of the engine is controlled to perform a shift operation. When a second torque controlled shift is detected while the transmission is currently executing the first torque controlled shift, a dual torque controlled shift strategy is executed, which merges a first shift control strategy for executing the first torque controlled shift with a second shift control strategy for executing the second torque controlled shift. The dual torque controlled shift strategy seamlessly executes the first torque controlled shift and the second torque controlled shift without a time delay and engine torque disruption therebetween.