Actuated Differential Gearing for Variable Torque Bias Control
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Solution Overview
Problem
Existing differential gearing systems, such as open and limited-slip differentials, fail to effectively manage torque distribution between wheels, leading to reduced traction and wheel spin issues, especially when one wheel begins to slip.
Innovation Solution
A differential gearing device incorporating a base gearing system with a Torsen-type limited-slip differential and an actuator that adjusts the torque bias ratio by engaging a clutch between the gears, allowing for increased torque distribution to the wheel with better traction while preventing unwanted wheel spin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an open differential is used to split torque between two wheels, then the differential can allow wheels to rotate at different speeds, but the output torque is reduced at the wheel with better traction when one wheel begins to slip
Solution Approach 1:
The differential gearing device dynamically adjusts the torque bias ratio between wheels based on operating conditions. The actuator modifies the gear ratios in real-time, transitioning from a fixed open differential configuration to a variable configuration that can bias torque toward the wheel with better traction, thereby resolving the contradiction between allowing speed differentiation and maintaining torque to the gripping wheel
Solution Approach 2:
The system changes the torque distribution parameter by adjusting the torque bias ratio through the actuator. By varying the gear ratios between the left and right wheels, the system can shift torque distribution from equal (open differential) to biased (when one wheel slips), directly addressing the torque loss problem while preserving speed differentiation capability
2Force
If a limited-slip differential is used to reduce wheel spin, then more torque is applied to the opposite wheel when one wheel begins to slip, but the torque distribution is fixed and cannot adapt to varying traction conditions
Solution Approach 1:
The differential device transforms the static torque bias ratio of traditional LSDs into a dynamic, adjustable parameter. The actuator enables real-time modification of gear ratios, allowing the system to adapt torque distribution to varying traction conditions, road surfaces, and driving scenarios, thereby providing both limited-slip functionality and adaptability
Solution Approach 2:
The differential gearing device combines multiple functions: it operates as an open differential when wheels have equal traction, transitions to a limited-slip differential when one wheel slips, and can further adjust to optimize torque distribution under various conditions. This multi-functionality resolves the contradiction by making the system adaptable to different operating scenarios
3Reliability
If a Torsen LSD with helical gears is used to effect limited slip function, then wheel spin is reduced, but the torque bias ratio is fixed and cannot be adjusted for different driving conditions
Solution Approach 1:
The actuator serves as an intermediary component that enables adjustment of the torque bias ratio in the Torsen LSD. By introducing this intermediate device, the system gains the ability to modify gear ratios and torque distribution without fundamentally redesigning the helical gear mechanism, thus improving traction management adaptability while controlling the increase in device complexity
Data Source
AI summary
A differential gearing device includes a base gearing device and an actuator. The base gearing device including a first gear connected to a first output of the differential gearing device, a second gear connected to a second output of the differential gearing device, differential gearing connected to each of the first gear and the second gear, and a clutch connected between the first gear and the second gear. The actuator actuates the clutch to change a torque bias ratio between the first gear and the second gear.