Two-Piece Limited Slip Differential for Compact Torque Biasing
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Solution Overview
Problem
Conventional limited slip differentials (LSDs) face spatial constraints and weight issues, limiting their integration in vehicles that frequently operate on low-traction surfaces, and lack sufficient space for differential gears due to preloaded clutch packs, necessitating spherical machining of satellite gears.
Innovation Solution
A two-piece differential case with an intermediate floating piece and adjustable preload mechanism, utilizing a shim and disc springs to evenly distribute torque among drive wheels based on tractive resistance, preventing wheel slip when parked on grades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LSD design is used with a preloaded clutch pack to achieve desired torque distribution, then torque distribution performance is improved, but the device footprint and weight exceed vehicle space and weight availability
Solution Approach 1:
The differential case is divided into a two-piece construction with separate clutch pack assemblies for each side gear. This segmentation allows each clutch pack to be independently sized and positioned, reducing the overall footprint while maintaining torque distribution functionality. The intermediate floating piece is also segmented into multiple functional components (sleeve assembly, planet gears, pin) that can be compactly arranged.
Solution Approach 2:
The planet gears and pin are positioned within the intermediate floating piece, which itself is positioned within the differential case. The clutch packs are nested between the side gears and the differential case. This nested arrangement maximizes space utilization and reduces the overall device footprint while maintaining all necessary functional components.
2Area of stationary object
If the clutch pack cavity is directly machined in the differential housing based on clutch pack size, then spatial constraints are satisfied, but spherical machining of satellite gears is demanded increasing manufacturing complexity
Solution Approach 1:
The differential case is segmented into two pieces that can be separately manufactured and then assembled. This allows the clutch pack cavity to be formed as part of the case geometry rather than requiring complex spherical machining of the satellite gears. The separate pieces can be manufactured using standard machining processes, reducing manufacturing complexity.
Solution Approach 2:
The intermediate floating piece acts as an intermediary component that mediates between the satellite gears and the clutch pack assembly. It provides a standardized interface that simplifies the machining requirements, allowing the clutch pack cavity to be formed without demanding spherical machining of the satellite gears themselves.
3Reliability
If disc springs are selected based on preload calculations to achieve desired LSD performance, then torque biasing is improved, but the device weight increases
Solution Approach 1:
The preload force is adjusted by changing the thickness of the shim rather than selecting larger or heavier disc springs. This parameter change allows precise control of torque biasing performance while maintaining lightweight spring components. The shim thickness can be varied to achieve different preload levels without increasing device weight.
4Area of stationary object
If a compact LSD design is used to reduce footprint and weight, then space and weight availability is improved, but torque distribution among drive wheels may be insufficient
Solution Approach 1:
The preload force applied to the clutch packs can be precisely adjusted by changing the shim thickness, allowing optimization of torque distribution for low-traction surface conditions. This parameter adjustment ensures sufficient torque biasing performance in a compact design. The disc spring properties can also be optimized for the reduced space while maintaining adequate preload capability.
Solution Approach 2:
The intermediate floating piece combines multiple functions (supporting planet gears, providing axial sliding capability, mediating between satellite gears and clutch packs) into a single compact component. This merging of functions reduces the overall device footprint while maintaining the torque distribution capability needed for low-traction surface performance.
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 design allows for efficient torque distribution and prevents wheel slip on varying traction surfaces, maintaining vehicle stability and reducing weight and footprint, suitable for vehicles with limited space.
Implementation Method 1
an intermediate floating piece positioned in an interior of the two-piece differential case and coupled to the two-piece differential case via splines that enable the intermediate floating piece to slide axially
Implementation Method 2
a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear
Implementation Method 3
a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear
Data Source
AI summary
Systems are provided for a limited slip differential (LSD). The LSD comprises a two-piece differential case, an intermediate floating piece positioned in an interior of the two-piece differential case and configured to slide axially therein. The LSD, further comprises a first side gear and a second side gear meshed with gears of the intermediate floating piece, a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear, a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear, and a second clutch pack mounted on the second side gear and positioned between the second disc spring and a lip of the second side gear, and a shim mounted on the second side gear and positioned axially between the second disc spring and the two-piece differential case.