Differential Gear Assembly Torque Bias Friction Plates
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Solution Overview
Problem
Existing differential gear systems struggle to effectively provide torque to driven wheels experiencing different road surface conditions, leading to reduced torque transmission when one wheel is on an icy or high-friction surface while the other is not, resulting in decreased vehicle performance.
Innovation Solution
A differential gear assembly with a first and second sun gear, planetary gears, and frictional interfaces, including a center preload assembly and friction plates, which allows for torque bias and controlled friction to manage driveline torque, ensuring adequate torque delivery to both wheels regardless of road surface conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional differential gear is used to allow driven wheels to rotate at different speeds, then the vehicle can navigate turns effectively, but torque is reduced to the non-slipping wheel when one wheel experiences high friction and the other low friction
Solution Approach 1:
A friction plate is introduced as an intermediary component between the pinion gear and the case body. This friction plate creates a friction-based connection that resists the pinion's rotation relative to the case, thereby generating a reaction force that increases torque delivery to the non-slipping wheel while still permitting speed differential between wheels during turning maneuvers.
2Ease of operation
If the pinion gear rotates freely relative to the case body, then smooth differential action is achieved during turns, but torque delivery to the non-slipping wheel decreases when wheels experience different road conditions
Solution Approach 1:
The friction connection between the pinion gear and case body is designed to be dynamic rather than fixed. The friction plate allows relative motion when needed (during turns) while providing resistive force when needed (during traction events). The system automatically adjusts its degree of freedom based on the operational conditions, balancing smooth differential action with torque multiplication.
Solution Approach 2:
The friction between the pinion gear and case body, which would normally be considered a source of loss or resistance, is converted into a beneficial torque-multiplying mechanism. By intentionally designing this friction connection through the friction plate, the resistance to pinion rotation becomes the source of increased torque delivery to the non-slipping wheel, turning a potential harmful effect into a useful function.
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 solution effectively reduces the rotational speed of the slipping wheel and increases torque to the non-slipping wheel, maintaining vehicle traction and performance even on varying road surfaces, by utilizing a preload assembly and friction plates to manage torque distribution.
Implementation Method 1
friction members which face respective axial outer surfaces of the planetary gears; and a second set of friction members which face respective other axial outer surfaces of the planetary gears
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A differential gear assembly is disclosed. The differential gear assembly includes a first sun gear and a second sun gear coaxially aligned with each other; a first set of planetary gears in mating engagement with the first sun gear; and a second set of planetary gears in mating engagement with the second sun gear. The first and second sets of planetary gears are in mating engagement with each other. The differential gear assembly also includes a first set of friction members, each of which faces a respective one of axial ends of the first set of planetary gears; and a second set of friction members, each of which faces a respective one of axial ends of the second set of planetary gears. The differential gear assembly further includes a first body connecting at least a plurality of said first set of friction members together, and a second body connecting at least a plurality of said first set of friction members together.