Transmission Shift Control via Dynamic Torque Adaptation
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Solution Overview
Problem
Automatic transmissions face challenges in efficiently shifting between gear ratios due to limitations in existing torque-transmitting mechanisms, particularly in responding to changing torque requests during shifts, which can result in incomplete gear changes and decreased driving performance.
Innovation Solution
A method for controlling shifts in multi-speed transmissions that involves an initial shift to a target gear, with the option to adjust to a higher speed ratio if a threshold increase in torque request is detected, utilizing a common controlling clutch that remains partially engaged throughout the process to avoid completing the initial shift and instead transition directly to the adjusted target gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission completes an initial shift to a target gear, then the gear change is finalized, but the transmission cannot respond to increasing torque requests by shifting to a higher speed ratio gear
Solution Approach 1:
The patent implements dynamic shift abort capability where the transmission control system can dynamically decide to abort an initial shift and execute an adjusted shift based on real-time torque requests. The system transitions from a static shift completion approach to a dynamic decision-making process that evaluates torque conditions during the shift process, allowing the transmission to adapt its gear selection based on changing powertrain demands.
Solution Approach 2:
The patent prepares the transmission for potential shift adjustments by maintaining clutches in intermediate engagement states during the initial shift process. Rather than fully completing the initial shift before considering adjustments, the system performs preliminary positioning of clutches that enables rapid transition to adjusted target gears when torque requests increase, reducing the time penalty associated with shift changes.
2Adaptability or versatility
If the transmission aborts an initial shift to execute an adjusted shift, then it can respond to torque requests, but the shift process becomes more complex
Solution Approach 1:
The patent makes the common controlling clutch serve multiple functions: it acts as the off-going clutch for the initial shift, the on-coming clutch for the adjusted shift, and the off-going clutch for the adjusted shift. This multi-functionality reduces the need for additional dedicated components for shift abort and adjustment operations, managing complexity while enabling adaptive gear selection.
Solution Approach 2:
The patent implements a feedback mechanism where the transmission control system continuously monitors torque requests during the shift process and uses this information to determine whether to abort the initial shift and execute an adjusted shift. The feedback loop evaluates whether the torque request exceeds a threshold that would benefit from a lower gear ratio, enabling intelligent adaptability without requiring overly complex control logic.
3Adaptability or versatility
If the transmission passes through neutral mode during shift adjustment, then gear changes can be made, but output acceleration smoothness is compromised
Solution Approach 1:
The patent maintains continuous torque transmission through the transmission system during shift adjustments by keeping the common controlling clutch partially engaged throughout the process. Rather than disengaging all clutches and passing through a neutral state, the system sustains a continuous torque path that allows smooth transition between gear ratios without interrupting power delivery, thereby maintaining output acceleration smoothness.
Solution Approach 2:
The patent applies partial engagement of the common controlling clutch during the shift adjustment process rather than full engagement or complete disengagement. This partial action allows the clutch to transmit torque while accommodating the speed ratio change, enabling gear adjustment without fully completing the initial shift or interrupting power flow through neutral, thus preserving acceleration smoothness.
Data Source
AI summary
A method of controlling shifts in a multi-speed transmission includes beginning an initial shift, which changes the transmission from a starting gear to an initial target gear, and executing an adjusted shift, which changes the transmission to an adjusted target gear having higher speed ratio than the initial target gear, when transition conditions are satisfied. The transition conditions include a threshold increase in torque request, which is sufficient to require the transmission to be placed into the adjusted target gear. The transition conditions also include a common controlling clutch, which is partially engaged during the initial shift and the adjusted shift and is an off-going clutch to place the transmission in the adjusted target gear. Executing the adjusted shift does not include placing the transmission in a neutral mode. Furthermore, executing the adjusted shift does not include completing the initial shift.