Parallel-axis helical differential with integral brake shoes
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Solution Overview
Problem
Existing parallel-axis helical differentials face issues with pinion tipping during high torque conditions, leading to misalignment and reduced torque transmitting capability, and current solutions with brake shoes increase complexity and wear.
Innovation Solution
A differential assembly design featuring a case body with integrally formed shoes and helical pinions that frictionally engage the interior wall surface in response to reaction forces from side gears, limiting differential motion and reducing tipping, while using a reduced component count and heat treatment for enhanced wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete brake shoes are mounted to pinions to apply frictional braking load, then speed differentiation is limited, but device complexity increases and wear resistance decreases
Solution Approach 1:
The brake shoe is integrally formed with the case body as a single unified component, eliminating the need for separate discrete brake shoes mounted to pinions. This merging of components reduces part count and assembly complexity while maintaining the frictional braking function against the pinion ends to limit speed differentiation.
Solution Approach 2:
The integral brake shoe structure utilizes the case body itself to provide the braking surface, eliminating the need for separate wearable components. The case body directly engages the pinion ends through friction, reducing wear on dedicated brake components and improving overall wear resistance of the differential assembly.
2Power
If pinions are allowed to move radially and axially during high torque conditions, then gearset flexibility is maintained, but gear contact misalignment occurs reducing torque transmitting capability
Solution Approach 1:
The integral brake shoe applies frictional braking force to the pinion ends in advance during high torque conditions, counteracting the radial and axial movements that would otherwise cause gear contact misalignment. This preliminary anti-action maintains proper gear engagement and preserves torque transmitting capability.
Solution Approach 2:
The frictional braking force from the integral brake shoe changes the operational parameters of the pinion by limiting its radial and axial displacement. This parameter control ensures that gear contact alignment is maintained within acceptable tolerances during high torque operation, optimizing power transmission.
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 effectively limits differential motion and enhances torque transmission, reduces wear, and simplifies the component count, improving the efficiency and durability of the differential assembly.
Implementation Method 1
The first and second helical pinions frictionally engage the interior wall surface of the case body in response to radially outwardly and axially directed reaction forces generated by meshing engagement with the first and second side gears, respectively, to thereby limit differential motion between the first and second side gears.
Data Source
AI summary
A differential assembly with a case assembly, a plurality of first and second shoes, a plurality of first and second helical pinions, and first and second side gears. The case assembly defines first and second apertures and includes a case body and a case cap. The first and second shoes are integrally formed with the case body and the case cover, respectively. The first pinions are meshingly engaged to the first side gear and have pin portions that are received into the first apertures. The second pinions are meshingly engaged to the second side gear and have pin portions that are received into the second apertures. The first and second helical pinions frictionally engage an interior wall surface of the case body in response to a reaction force generated by meshing engagement with the first and second side gears, respectively, to limit differential motion between the first and second side gears.