Nested Gear Shift Control for Automatic Transmissions
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Solution Overview
Problem
Existing methods for operating automatic transmissions with five switching elements, where three are closed and two are open for torque transmission, are not suitable for transmissions with eight forward gears and one reverse gear, as they do not efficiently support nested upshifts and downshifts, leading to a lack of smooth gear transitions and increased switching speed.
Innovation Solution
A method that allows for interleaved upshifts and downshifts by controlling the switching elements, where a first switching element is opened or closed, and a second switching element is prepared for opening or closing, with a third switching element being prepared for closing during the transition, ensuring that at least one switching element remains closed to support successive shifts, and torque adjustments are made to facilitate smooth gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional shifting methods are used in automatic transmissions with five switching elements (three closed, two open), then the transmission can operate with standard gear changes, but successive upshifts and downshifts cannot be executed efficiently, leading to slower switching speed and less smooth gear transitions
Solution Approach 1:
The patent applies preliminary action by preparing switching elements for subsequent gear changes during the current gear transition. Specifically, during a first upshift or downshift, the method prepares a switching element required for a second subsequent upshift or downshift in advance. This preparation occurs during the synchronization phase of the first shift, enabling the second shift to execute immediately when its synchronization point is reached, thereby achieving nested successive shifts without waiting for complete separation of shifts.
Solution Approach 2:
The patent implements nesting by executing multiple gear shifts in a nested manner where a second upshift or downshift is initiated and prepared during the execution of a first upshift or downshift. The switching elements are controlled in nested sequences where the control of one switching element during the transition to the next gear is coordinated with the preparation of subsequent switching elements, creating a nested structure of gear transitions that improves overall switching efficiency.
2Adaptability or versatility
If the number of forward gears in automatic transmission is increased to eight or more, then the transmission provides better performance across different driving conditions, but existing shifting methods become unsuitable and require complex switching element control
Solution Approach 1:
The patent applies universality by developing a generalized control method that works for automatic transmissions with five switching elements regardless of whether they are configured with three closed and two open elements or other configurations. The method provides a universal approach for controlling nested successive upshifts and downshifts that can be applied to transmissions with six, seven, eight, or more forward gears, as well as reverse gears, using the same five switching elements through different control sequences.
Solution Approach 2:
The patent implements dynamics by making the control of switching elements adaptive and flexible rather than fixed. The control method dynamically adjusts which switching elements are opened or closed based on the current gear state and the desired target gear. The synchronization points and timing of switching element operations are dynamically determined based on real-time transmission state, enabling the system to handle various gear configurations and shifting scenarios with the same hardware.
3Productivity
If switching elements are prepared for subsequent shifts during current shifts, then nested successive upshifts and downshifts can be executed, but the control logic becomes more complex requiring coordination of multiple switching elements
Solution Approach 1:
The patent applies segmentation by dividing the gear shift process into distinct phases and controlling different switching elements in segmented sequences. The method segments the control of switching elements into first upshift/downshift operations and second subsequent upshift/downshift operations, with each phase having specific switching elements that are opened or closed. This segmentation allows complex nested shifts to be broken down into manageable control steps, reducing the perceived complexity of the control logic.
Solution Approach 2:
The patent implements feedback by continuously monitoring the state of switching elements and adjusting the control sequence based on the current transmission state. The control system uses feedback from the synchronization points of gear shifts to determine when to prepare and execute subsequent shifts. This feedback mechanism ensures that nested successive upshifts and downshifts are coordinated properly, with each switching element operation timed correctly based on the actual state of the transmission rather than following a rigid predetermined sequence.
Data Source
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AI summary
The invention relates to a method for operating a drive train of a motor vehicle comprising at least one automatic transmission and one drive unit. According to the invention, in an automatic transmission with five shift elements, of which three shift elements are closed and two shift elements are open for torque or power transmission in a forward gear or a reverse gear, two successive upshifts or two successive downshifts can be performed in such a nested manner that: a) during the execution of a first upshift or downshift, a first shift element is opened according to a first alternative or closed according to a second alternative, and a second shift element is closed according to the first alternative or opened according to the second alternative; b) during the execution of the first upshift or downshift, for a subsequent second upshift or downshift, the shift element is closed according to the first alternative or opened according to the second alternative.c) the second switching element after the first alternative to open or after the second alternative to close, as well as a third switching element after the first alternative to close or after the second alternative to open, is prepared for reversal, wherein the control of the second switching element during the transition from the first up-switching or reversal to the second up-switching or reversal is carried out after the first alternative via a minimum selection or after the second alternative via a maximum selection; c) during the execution of the first up-switching or reversal and during the execution of the second up-switching or reversal, at least a fourth switching element is closed or kept nearly closed.