Automatic Transmission Nested Shifting Control
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Solution Overview
Problem
Existing methods for operating automatic transmissions with five or more switching elements are not suitable for advanced transmissions with eight forward gears and one reverse gear, as they fail to efficiently perform nested upshifts and downshifts.
Innovation Solution
A method that involves strategically opening and closing switching elements during upshifts and downshifts to prepare for subsequent gear changes, utilizing a minimum or maximum selection control, and maintaining specific switching elements closed during transitions to enable efficient nested gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the automatic transmission has eight forward gears and one reverse gear with at least five switching elements, then the gear range and versatility are improved, but the complexity of controlling nested upshifts and downshifts increases significantly
Solution Approach 1:
The patent segments the gear shifting process into distinct phases: first upshift/downshift execution and second upshift/downshift preparation. During the first shift, specific switching elements are prepared in advance for the second shift, allowing complex eight-speed transmissions to manage multiple gear changes systematically without overwhelming control complexity
Solution Approach 2:
The patent applies preliminary action by preparing switching elements for the second upshift or downshift during the execution of the first upshift or downshift. This advance preparation ensures that when the first shift completes, the second shift can immediately follow without delay, enabling efficient nested gear changes in eight-speed transmissions
2Ease of operation
If successive upshifts or downshifts are executed sequentially without nesting, then the control logic is simpler, but the shifting speed and responsiveness to driver requests deteriorate
Solution Approach 1:
The patent prepares switching elements for the second shift during the first shift execution, enabling immediate sequential execution without waiting for the first shift to fully complete. This preliminary preparation maintains simple control logic while dramatically improving shifting speed and responsiveness to driver requests
Solution Approach 2:
The patent implements nested shifts where the second upshift or downshift is prepared and executed within the time frame of the first shift. This nesting allows multiple gear changes to occur in overlapping time periods, improving overall shifting speed while maintaining manageable control logic through structured preparation sequences
3Productivity
If switching elements are prepared for subsequent shifts during current shifts, then the nested shift execution speed is improved, but the risk of timing conflicts and control errors increases
Solution Approach 1:
The patent segments the switching element control into specific phases: which elements to open/close during the first shift, which to prepare for the second shift, and which to keep closed throughout. This segmentation eliminates timing conflicts by assigning distinct roles to different switching elements, maintaining reliability while enabling fast nested shifts
Solution Approach 2:
The patent dynamically adjusts switching element states based on the current shift phase. During the first upshift/downshift, certain elements are prepared for the second shift, and the control system adaptively manages transitions between preparation and execution phases, ensuring reliable timing even during rapid nested gear changes
Data Source
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AI summary
The method involves providing an automatic transmission (2) with five switching units, where three units are closed and two units are opened for torque- and/or power transmission in forward and/or reverse gears. Three switching units are alternatively opened and closed, during implementation of the one of stepping and/or shifting operations. One of the switching units is controlled during transition from one of the operation to other operation over a minimum or maximum range. The fourth switching unit is closed and/or opened during implementation of two operations.