Ribbed Axle Housing Structure for Lower Mass and Oil Volume
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Solution Overview
Problem
Existing axle housings require thick walls to withstand bending and torsional stresses, leading to increased mass and the need for excessive lubricating oil due to a constant rectangular box section profile.
Innovation Solution
The axle housing incorporates ribs extending parallel to the leg portions, reducing wall thickness while increasing rigidity and second moment of area, and features a tapered tubular casing to minimize mass and oil volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick walls are used in the leg portions to withstand bending and torsional stresses, then the strength and rigidity of the axle housing is improved, but the mass of the axle housing increases significantly
Solution Approach 1:
The patent transitions from a two-dimensional box section to a three-dimensional structure by adding ribs that extend into the void space. These ribs increase the second moment of area and structural rigidity without increasing the external dimensions or wall thickness, effectively utilizing the third dimension to enhance strength while maintaining low mass
Solution Approach 2:
The leg portion is segmented into multiple structural elements: the tubular casing and multiple ribs extending from it. This segmentation allows each element to be optimized independently - the tubular casing provides basic structural support while the ribs add targeted reinforcement in specific directions, achieving high strength-to-weight ratio
2Ease of manufacture
If a constant profile box section is used for the leg portions, then the manufacturing process is simplified, but a large quantity of oil is needed to sufficiently fill the axle housing to maintain minimum lubrication
Solution Approach 1:
The patent applies local quality by creating a variable profile tubular casing where the cross-sectional area varies along the length. The casing has a larger cross-section near the differential portion and tapers toward the free end. This allows oil to be concentrated where it is most needed (near the differential and wheel end assemblies) while reducing oil volume in less critical areas, thereby reducing total oil quantity while maintaining adequate lubrication
3Stability of the object's composition
If the leg portions are formed as rectangular box sections, then the structural stiffness is improved, but the mass of the axle housing increases due to the requirement for thick walls
Solution Approach 1:
The leg portion is formed as a composite structure consisting of a tubular casing with multiple ribs integrated into it. This composite configuration creates a complex structural form that achieves high stiffness-to-weight ratio by combining the basic tubular structure with additional rib elements that provide targeted reinforcement without the mass penalty of a solid box section
Data Source
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AI summary
An axle housing comprising: a differential portion configured to receive a differential; and a pair of elongate leg portions extending from opposite sides of the differential portion. Each leg portion comprises a free end configured for mounting a wheel end assembly to the axle housing. Each leg portion is configured to house a drive shaft for transmitting torque from the differential to the wheel end assembly. At least one of the leg portions comprises one or more ribs extending substantially parallel to a longitudinal axis of the leg portion.