EV Driveline Disconnect Control for Predictable 2WD-4WD Shifting
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Solution Overview
Problem
In electric four-wheel drive vehicles, the randomness of left versus right wheel connection during shifting between two-wheel and four-wheel drive configurations is undesirable due to sophisticated control systems and sensors, which traditional simultaneous disconnect methods cannot address.
Innovation Solution
Implementing a sequential and overlapping shift process for driveline actuators in electric vehicles, where one wheel disconnect is initiated first, followed by the second after a controlled time delay, ensuring predictable engagement order and minimizing overall shift time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simultaneous wheel disconnect shifting is used, then device complexity is reduced, but manufacturing precision and control reliability deteriorate due to random connection order
Solution Approach 1:
The control system initiates the first wheel disconnect shifting action before the second wheel disconnect, creating a predetermined sequence. This preliminary action ensures that the left wheel connects before the right wheel, eliminating random connection order while maintaining manageable device complexity through controlled timing sequences
2Manufacturing precision
If sequential wheel disconnect shifting is implemented, then wheel connection order precision is improved, but shifting time increases
Solution Approach 1:
The patent merges the two wheel disconnect shifting processes by initiating the second wheel disconnect while the first is still in progress, rather than waiting for complete completion. This overlapping approach combines the sequential precision requirement with time efficiency, reducing total shifting time by approximately 70 milliseconds compared to fully sequential execution
3Productivity
If overlapping shift process is used, then productivity is improved by reducing shift time, but device complexity increases due to coordinated control requirements
Solution Approach 1:
The control system employs feedback mechanisms to monitor the status of each wheel disconnect actuator and adjust timing accordingly. Sensors detect the position and movement state of disconnect components, providing real-time information to the controller, which then coordinates the overlapping shift operations to achieve optimal productivity while managing control complexity through intelligent timing adjustments
Data Source
AI summary
In general, this disclosure relates to a system and method of control for driveline actuators (DLAs) in the powertrain of an electric vehicle to perform shifting between two-wheel drive (2WD) and four-wheel drive (4WD) configurations. Sequential and overlapping shift process is used. The first disconnect is instructed by a vehicle control system to begin its shift, which takes approximately 100 milliseconds to complete. A short period of time after the first disconnect is instructed to begin its shift, but before it has completed the shift, the second disconnect is instructed to begin.