Centrifugal Spring Mass Actuator for Limited Slip Differentials
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Solution Overview
Problem
Current limited slip differentials in motor vehicles often rely on complex mechanical or hydrodynamic systems, which increase weight, cost, and complexity, and can lead to torque loss and design issues, particularly when there is no wheel slip.
Innovation Solution
A centrifugal-spring actuated limited slip differential that uses expanding centrifugal springs to engage friction plates and lock the differential when a wheel slips, eliminating the need for complex clutch packs and hydrodynamic hardware, thereby providing a more compact, lightweight, and cost-effective solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex mechanical or hydrodynamic systems are used in limited slip differentials, then limited slip capability is achieved, but weight, cost, and device complexity increase
Solution Approach 1:
The patent extracts and eliminates complex mechanical components (clutch packs, hydrodynamic hardware, expansion plates) from the limited slip differential system. The invention achieves limited slip capability using only a simplified set of components: friction plates, return springs, and biasing springs, thereby reducing device complexity while maintaining the essential limited slip function.
Solution Approach 2:
The patent replaces complex mechanical systems (multiple clutch packs, hydrodynamic mechanisms) with a simpler mechanical system using friction plates actuated by springs. This substitution maintains the limited slip capability while significantly reducing the number of moving parts and overall system complexity.
2Reliability
If complex clutch packs and hydrodynamic hardware are used, then limited slip capability is achieved, but part and assembly costs increase
Solution Approach 1:
The patent removes expensive components such as clutch packs, hydrodynamic hardware, and expansion plates from the differential design. By eliminating these complex and costly parts, the invention achieves limited slip capability through a simpler, more cost-effective assembly of friction plates and springs.
Solution Approach 2:
The patent employs simple, inexpensive friction plates and spring mechanisms instead of expensive clutch packs and hydrodynamic components. These simpler components are easier and cheaper to manufacture and assemble, reducing overall part and assembly costs while maintaining functional effectiveness.
3Reliability
If complex mechanical systems are used, then limited slip capability is achieved, but packaging space increases
Solution Approach 1:
The patent extracts and eliminates bulky components such as clutch packs, hydrodynamic hardware, and expansion plates from the differential assembly. This extraction of unnecessary components significantly reduces the overall volume and packaging space required while preserving the limited slip differential's core functionality.
Solution Approach 2:
The patent merges multiple functions into simpler components. The friction plates perform both the friction-based torque transfer and the structural function previously requiring separate clutch packs and expansion plates. This merging of functions reduces the total number of parts and the space they occupy.
4Reliability
If traditional limited slip differentials are used, then wheel speed disparity is limited, but torque loss occurs and design complications arise
Solution Approach 1:
The patent replaces complex mechanical systems (clutch packs, hydrodynamic mechanisms) that cause torque loss with a simpler friction plate and spring system. This substitution reduces mechanical inefficiencies and energy losses while maintaining effective wheel speed control and limited slip capability.
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
This design enhances torque transfer efficiency by equalizing wheel speed during slips, reduces part and assembly costs, and minimizes packaging space while avoiding torque loss and design complications associated with traditional systems.
Implementation Method 1
the springs will expand radially outward when there is a difference between the relative speeds of the two axle half shafts
Implementation Method 2
press the friction plates into engagement with complementary friction surfaces attached to the differential side gears to lock the differential
Data Source
AI summary
Limited slip differentials (LSD), methods for making and methods for using such LSDs, and motor vehicles employing an LSD. An LSD for a motor vehicle includes a differential casing that drivingly connects to the driveshaft, and two side gears rotatably mounted inside the casing. Each side gear drivingly connects to a respective axle shaft. One or both side gears includes a respective friction surface. One or more pinion gears are mounted inside the casing and meshingly engaged with the side gears. One or more friction plates are movably mounted inside the casing to selectively engage with and disengage from a friction surface. A centrifugal spring mass, which is mounted to one of the pinion gears, includes circumferentially spaced springs that expand responsive to a predetermined disparity in rotational speed between the side gears and thereby urge the friction plate(s) into engagement with the friction surface(s).