Limited-Slip Differential Layout for Equal-Length Axles
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Solution Overview
Problem
Existing electronically controlled limited-slip differentials (LSDs) face challenges in achieving equal length axles due to the necessary biased positioning of the multi-plate clutch and actuator, leading to differences in axle characteristics and potential vehicle design issues.
Innovation Solution
The proposed differential device includes a casing with a differential gear set, a friction clutch, a cam mechanism, and a transmission member that allows for symmetrical arrangement, enabling equal length axles by differentially distributing torque and applying thrust force to the friction clutch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the multi-plate clutch and actuator are disposed in a biased position toward one end to enable differential limitation, then the differential lock function is achieved, but the axles cannot be made equal in length leading to differences in axle characteristics
Solution Approach 1:
The invention relocates the actuator from a radial position to an axial position at the end of the differential case. This dimensional change allows the actuator to apply force through the pinion shafts in the axial direction, enabling symmetric torque distribution to both side gears while maintaining equal axle lengths. The cam mechanism converts rotational motion to axial thrust, which is then transmitted symmetrically to both pinion shafts.
Solution Approach 2:
The invention introduces transmission members (plungers and collars) as intermediaries between the actuator and the pinion shafts. These intermediaries transmit the axial thrust force from the actuator to the pinion shafts in a symmetric manner, ensuring equal torque distribution to both side gears. The transmission members act as mediators that convert the single-point actuator force into balanced dual-sided torque application.
2Reliability
If the multi-plate clutch is disposed adjacent to the side gear to limit differential motion, then the friction braking function is achieved, but the device complexity increases due to additional components and biased positioning
Solution Approach 1:
The invention merges the friction clutch function with the side gear structure itself. The friction surfaces are integrated into the side gear, eliminating the need for a separate multi-plate clutch assembly. This integration reduces component count and simplifies the overall device structure while maintaining the differential motion limitation function through axial thrust application.
Solution Approach 2:
The invention extracts the multi-plate clutch mechanism and replaces it with a simpler friction braking system integrated into the side gear. By removing the complex multi-plate clutch assembly and its associated actuator positioning requirements, the invention achieves differential limitation with fewer components and simpler arrangement.
3Ease of operation
If the actuator is positioned to apply pressure force onto the multi-plate clutch, then the degree of differential limitation is controllable, but the compact size of the differential device is compromised due to biased positioning requirements
Solution Approach 1:
The invention positions the actuator at the axial end of the differential case rather than radially adjacent to the side gear. This axial positioning utilizes the existing end space of the differential case, avoiding additional radial or lateral space requirements. The cam mechanism efficiently converts rotational actuator motion to axial thrust, maintaining compact overall dimensions while enabling controlled differential limitation.
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 solution allows for equal length axles, maintains the compact size of the differential device, and ensures compatibility with vehicle design without substantial changes, effectively addressing the limitations of existing LSDs.
Implementation Method 1
a cam mechanism disposed outside the casing, contiguous to the second wall and coaxial with the axis, the cam mechanism being configured to convert a rotational force about the axis into a thrust force in a direction of the axis
Implementation Method 2
a friction clutch disposed between the first side gear and the first wall to brake the first side gear against the first wall
Data Source
AI summary
A differential device is provided with a casing including a first wall, a second wall and a peripheral wall and defining a chamber; a differential gear set housed in the chamber and including a first side gear, a second side gear and pinion gears respectively rotatably supported by pinion shafts; a friction clutch disposed between the first side gear and the first wall to brake the first side gear against the first wall; a cam mechanism disposed outside the casing, contiguous to the second wall and configured to convert a rotational force into a thrust force in a direction of an axis; and a transmission member including plungers elongated in parallel with the axis through intervals between the pinion gears or between the pinion shafts and capable of transmitting the thrust force.