Differential Case Flange Stress Dispersion
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Solution Overview
Problem
The concentration of stress at the rounded base of a differential case flange welded to a ring gear in a vehicle differential apparatus is excessive due to changes in the point of gear reaction force application and thermal contraction, leading to increased moment loads and stress, which existing solutions attempt to address by increasing the rounded base size or using high-strength materials, both of which have disadvantages.
Innovation Solution
Incorporating two rounded parts on the outer periphery of the differential case between the flange and the supported parts to disperse the stress generated by the gear reaction force, allowing the differential case to be rotatable and reducing stress concentration without increasing the rounded base size or using high-strength materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If welding is used to join the ring gear to the differential case, then weight reduction and high mileage are achieved, but excessive stress concentration occurs at the rounded base of the flange
Solution Approach 1:
The patent applies curvature by forming rounded parts at the base of the flange where it joins the differential case. These rounded portions distribute the stress that would otherwise concentrate at sharp corners, thereby reducing stress concentration while maintaining the welded fixing structure's weight and durability benefits
2Stress or pressure
If the rounded base size is increased to reduce stress concentration, then stress dispersion improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of increasing the overall flange size or complexity, the patent applies local quality by adding rounded parts only at the specific location where stress concentration occurs (at the base of the flange). This localized modification effectively reduces stress without requiring changes to the entire flange structure
3Strength
If high-strength materials are used to withstand stress concentration, then structural integrity improves, but manufacturing cost increases
Solution Approach 1:
The patent uses geometric curvature (rounded parts) as a stress-distributing feature rather than relying on high-strength materials. This design approach maintains structural integrity through shape optimization, avoiding the need for expensive material upgrades
Data Source
AI summary
A differential case includes: two supported parts so supported that a differential case is rotatable around a central axis of the differential chamber; and a flange provided between the supported parts and projecting in an outer diameter direction, and welded with a ring gear. The flange includes a bearing surface and a rounded base disposed on one side of the differential case in an axial direction. The bearing surface is in contact with a surface, of the ring gear, disposed on opposite side of a tooth surface of the ring gear, and the rounded base is coupled in a continuous fashion to the bearing surface. A rounded part that disperses stress, generated at the rounded base by gear reaction force derived from the ring gear, is provided in a region between the flange and one of the supported parts disposed on the one side.