Dual Limited Slip Differential Control for Rough-Road EV Traction
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Solution Overview
Problem
Existing electric vehicles with limited slip differentials (LSD) installed only on the main driveshaft struggle to effectively navigate rough roads due to insufficient differential limitation performance and rapid output velocity, especially on uneven terrain.
Innovation Solution
The implementation of first and second limited slip differentials on both the front and rear driveshafts, controlled by a controller to adjust sensitivity and clutch torques based on driving modes, including a rough road mode that reduces motor sensitivity and sets clutch torques to maximum for enhanced traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LSD is installed only on the main driveshaft, then the vehicle structure is simpler and easier to manufacture, but the differential limitation performance is insufficient on rough roads
Solution Approach 1:
The patent divides the driveshaft system into two separate segments: front driveshaft and rear driveshaft. Each driveshaft is equipped with its own LSD unit, allowing independent differential limitation control for front and rear wheels. This segmentation enables the vehicle to effectively handle rough road conditions where diagonal wheel slip occurs, resolving the contradiction between manufacturing simplicity and differential limitation performance.
2Power
If the drive motor utilizes maximum output in rough road, then the power delivery is maximized, but the vehicle cannot escape the rough road effectively due to rapid output velocity increase
Solution Approach 1:
The patent implements a controller that dynamically adjusts the clutch torque of the LSD units based on driving conditions. In rough road mode, the controller modulates the clutch torque to control the rate of torque transfer, preventing sudden output velocity increases while maintaining adequate power delivery. This dynamic control resolves the contradiction between maximizing power output and controlling the rate of velocity increase for effective rough road escape.
Data Source
AI summary
In an electric vehicle and a method of controlling the same, the electric vehicle may include: a drive motor generating power required for driving a vehicle; a first limited slip differential limiting a differential action by a first differential apparatus mounted on a first driveshaft; a second limited slip differential limiting the differential action by a second differential apparatus mounted on a second driveshaft; and a controller controlling a control sensitivity of the drive motor, and control amounts of the first limited slip differential and the second limited slip differential according to a driving mode of the vehicle.