Controllable Speed Differential for Torque Vectoring
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Solution Overview
Problem
Conventional vehicle differential systems face challenges in balancing traction and energy efficiency, particularly in high-performance vehicles, as they often result in unacceptable slippage during cornering and increase frictional and drag losses when switching between four-wheel-drive and two-wheel-drive modes.
Innovation Solution
A controllable speed differential system that combines the benefits of a limited slip differential with power disconnect capabilities, utilizing a ring gear, planetary gears, and an electronic machine to enable variable speed distribution between wheels, allowing for torque vectoring and efficient power transmission through a single gear, thereby reducing frictional losses and enhancing cornering capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional open differential is used, then the wheels can rotate at different speeds during turns, but the wheel with least traction determines maximum transferable torque resulting in unacceptable slippage
Solution Approach 1:
The patent employs a limited slip differential mechanism that dynamically adjusts torque distribution between wheels based on traction conditions. The differential allows speed differentiation during turns while automatically transferring torque to the wheel with higher traction, preventing slippage through mechanical friction elements that engage when speed differential exceeds a threshold.
2Reliability
If a locked differential is used, then torque can be transferred to the wheel with higher traction, but the wheels are locked together preventing speed differentiation during turns
Solution Approach 1:
The limited slip differential mechanism dynamically transitions between locked and unlocked states based on operating conditions. During straight-line acceleration, the friction elements lock the differential to transfer torque to the wheel with traction. During turns, the mechanism allows speed differentiation by reducing the locking effect, enabling the vehicle to navigate corners while maintaining traction control when needed.
3Reliability
If four-wheel-drive with transfer case and second differential is used, then traction is improved, but frictional and drag losses significantly increase affecting energy efficiency and driving range
Solution Approach 1:
The patent removes the transfer case and second differential from the four-wheel-drive system, extracting only the essential torque transfer function. By eliminating these intermediate components, the design reduces the number of gear meshes and friction points, significantly lowering drag losses while maintaining the ability to distribute torque to all wheels when traction is needed.
4Loss of energy
If disconnect system switching from four-wheel-drive to two-wheel-drive is used, then energy efficiency is improved, but the vehicle must be stationary to switch and frictional losses remain when connected
Solution Approach 1:
The disconnect system incorporates a dynamic clutch mechanism that can engage and disengage the four-wheel-drive connection while the vehicle is moving. This allows seamless transition between two-wheel-drive and four-wheel-drive modes without requiring the vehicle to stop, maintaining energy efficiency when four-wheel-drive is not needed while providing on-demand traction when conditions require it.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controllable speed differential system improves cornering performance and acceleration by dynamically adjusting wheel speeds and torque distribution, reducing energy losses and enhancing driving range and fuel efficiency.
Implementation Method 1
a first planetary gear carrier, the first planetary gear carrier carrying a plurality of first planetary gears at least partially positioned within the ring gear
Data Source
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AI summary
A vehicle differential configured to enable variable speed between a first output shaft and a second output shaft, the vehicle differential including a ring gear, a first planetary gear carrier, the first planetary gear carrier carrying a plurality of first planetary gears at least partially positioned within the ring gear, the first planetary gear carrier operably coupled to a first output shaft, a second planetary gear carrier, the second planetary gear carrier carrying a plurality of second planetary gears at least partially positioned within the ring gear, the second planetary gear carrier operably coupled to a second output shaft, a first sun gear at least partially positioned within the plurality of first planetary gears, a second sun gear at least partially positioned within plurality of the second planetary gears, and a distributor shaft and reversal gear operably coupling the first sun gear to the second sun gear.