Overlapping Gearshifts in Automatic Transmissions
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Solution Overview
Problem
Existing methods for operating automatic transmissions with a large number of gears, such as those with eight forward gears and one reverse gear, are not suited for efficient shifting due to the need for multiple shift elements to be disengaged, limiting the effectiveness of overlap in upshifts and downshifts.
Innovation Solution
A method that allows for overlapping consecutive upshifts and downshifts by selectively engaging and disengaging shift elements in an automatic transmission with at least five shift elements, where a maximum of two are disengaged during torque transfer, enabling multiple gearshifts to be prepared and executed efficiently, including maintaining at least one shift element engaged throughout the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of shift elements are disengaged to implement many forward gears, then the number of gears increases, but the shifting speed and efficiency deteriorate due to inability to perform overlapping shifts
Solution Approach 1:
The patent applies preliminary action by preparing the shift element for the second gearshift in advance during the execution of the first gearshift. Specifically, while the first shift element is being opened and the second shift element is being closed for the first gearshift, the third shift element is prepared for opening and the fourth shift element is prepared for closing before the first gearshift completes, enabling immediate execution of the second gearshift without waiting for synchronization.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that at least one shift element remains engaged throughout the entire process of performing both gearshifts. This continuous engagement of the fifth shift element allows the transmission to maintain torque transfer capability while multiple gearshifts are being prepared and executed in sequence, preventing interruption in the power transmission function.
2Adaptability or versatility
If multiple shift elements are disengaged for torque transfer, then more gears can be implemented, but the complexity of coordinating overlapping shifts increases
Solution Approach 1:
The patent segments the gearshift process into distinct phases: first gearshift execution (opening first shift element, closing second shift element), second gearshift preparation (opening third shift element, closing fourth shift element), and continuous torque transfer (maintaining fifth shift element engaged). This segmentation allows complex multi-element coordination to be broken down into manageable, sequential operations that can be independently controlled and synchronized.
Data Source
AI summary
A method for operating a motor vehicle drivetrain with at least an automatic transmission and a drive motor. The automatic transmission includes at least five shifting elements to transmit torque and/or power. In each forward and reverse gear a maximum of two shifting elements are disengaged while the remaining shifting elements are engaged. Two consecutive gearshifts are carried out through selection of the five shifting elements. During a first gearshift, implemented as a multiple gearshift, a subsequent second gearshift, implemented as either a single or multiple gearshift, is prepared. During the first gearshift, a first shifting element is disengaged, a second shifting element is engaged, a third shifting element is prepared for disengagement in a subsequent second gearshift and a fourth shifting element is prepared for engagement. Further, during the first gearshift and the subsequent second gearshift, a fifth shifting element is retained in at least a substantially engaged state.