Drivetrain Shift Speed via Overlapping Gear Changes
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Solution Overview
Problem
Existing methods for operating automatic transmissions in motor vehicle drivetrains do not efficiently implement overlapping upshifts and downshifts, which can lead to suboptimal shift speed and torque management.
Innovation Solution
The method involves actuating four shift elements to perform two successive upshifts or downshifts as a multiple shift followed by a single shift, where specific shift elements are opened and engaged in a controlled manner to prepare for the subsequent shift, and adjusting torque based on driver input to support overlapping shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If single shifts are overlapped with one another as in prior art, then shift speed is improved, but the complexity of shift element coordination increases and torque management becomes suboptimal
Solution Approach 1:
The patent segments the shift process into two distinct types: multiple shifts (actuating multiple shift elements simultaneously) and single shifts (actuating one shift element). This segmentation allows the system to choose the appropriate shift type based on the specific gear change required, simplifying the coordination logic compared to universal overlapping while maintaining high shift speeds.
Solution Approach 2:
The patent prepares the drive motor torque in advance before the actual shift execution. By pre-adjusting the torque based on the upcoming shift requirements, the system optimizes torque management and reduces the complexity of real-time coordination during the shift event itself.
2Speed
If multiple shift elements are actuated simultaneously in multiple shifts, then shift speed is further improved, but the torque management complexity and control precision requirements increase
Solution Approach 1:
The patent dynamically selects between multiple shifts and single shifts based on the specific gear change requirements. By making the shift strategy adaptive rather than fixed, the system achieves high shift speeds when multiple shifts are appropriate while avoiding unnecessary control precision demands when single shifts suffice.
Solution Approach 2:
The patent changes the torque parameter of the drive motor in advance according to the type of shift to be executed. This pre-adjustment of torque parameters simplifies the control precision requirements during the actual shift execution, as the system is already in the optimal torque state when multiple shift elements are actuated simultaneously.
3Reliability
If shift elements are prepared at the synchronization point as in prior art, then shift execution is timely, but the overall shift cycle time is extended
Solution Approach 1:
The patent prepares shift elements and adjusts torque in advance, before the synchronization point is reached. This preliminary preparation reduces the actual execution time at the critical moment while maintaining reliable timing, thereby shortening the overall shift cycle time compared to waiting until the synchronization point for preparation.
Data Source
AI summary
A method for the operation of a drivetrain of a motor vehicle, having an automatic transmission and a drive motor, to improve the shift speed. Successive upshifts or successive downshifts are carried out with overlap during a first upshift or downshift. At least one shift element required for a subsequent second upshift or downshift is prepared during the first upshift or downshift, in progress, when a synchronization point is reached. The subsequent second upshift or downshift are carried out immediately. Two successive upshifts or two successive downshifts are carried out by actuation of four shift elements of the automatic transmission.