Aircraft Shock Absorber Bearing Assembly Wear Reduction
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Solution Overview
Problem
Bearing assemblies for aircraft shock absorber struts experience wear due to lateral deflection forces, particularly at the lower bearing ring, leading to point contact and high pressure, which existing solutions attempt to mitigate through tapering or special assembly requirements.
Innovation Solution
A bearing assembly with axially tapered grooves in the housing to accommodate flexing bearing rings, allowing standard snap-in bearings to expand and increase contact area, reducing wear and friction, and optionally featuring multiple bearing rings with progressively larger diameters to distribute load evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner surface of the bearing ring is tapered to increase contact area, then wear is reduced, but the risk of incorrect assembly increases
Solution Approach 1:
The bearing ring is designed with an asymmetric tapered surface that provides increased contact area for wear reduction. The asymmetry is resolved by providing a corresponding asymmetric feature in the housing groove that guides the bearing ring into the correct orientation during assembly, eliminating the risk of incorrect installation while maintaining the wear-reducing tapered surface.
Solution Approach 2:
An intermediary guiding feature is introduced between the bearing ring and housing groove. This intermediary feature acts as a mechanical guide that passively directs the bearing ring into the correct orientation during assembly, removing the need for operator judgment or memory while maintaining the beneficial tapered contact surface.
2Ease of manufacture
If standard snap-in bearing rings are used, then ease of assembly and cost are improved, but they cannot accommodate lateral deflection forces without creating point contact
Solution Approach 1:
The bearing ring is designed with a localized tapered surface in the region subject to lateral deflection forces. This local quality change allows the bearing ring to maintain standard cylindrical geometry for most of its surface (enabling simple snap-in assembly) while providing enhanced contact area specifically where needed to distribute lateral loads and prevent point contact.
Solution Approach 2:
The bearing ring is designed to be flexible enough to deform elastically under lateral deflection forces, allowing it to conform to the tapered groove geometry in the housing. This dynamic response enables standard snap-in bearings to adapt to lateral loads and distribute contact pressure evenly without requiring pre-tapered rigid bearing surfaces.
3Reliability
If bearing rings are made flexible to accommodate deflection, then contact area increases, but control over bearing geometry becomes more difficult
Solution Approach 1:
The bearing ring is designed with a localized tapered surface in the region subject to lateral deflection forces. This local quality change allows the bearing ring to maintain standard cylindrical geometry for most of its surface (enabling simple snap-in assembly) while providing enhanced contact area specifically where needed to distribute lateral loads and prevent point contact.
Solution Approach 2:
The thickness and material properties of the bearing ring are carefully selected to provide controlled flexibility. By adjusting these parameters, the bearing ring achieves sufficient elastic deformation to conform to the tapered groove under load while maintaining adequate geometric precision and dimensional stability during normal operation and assembly.
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 solution effectively reduces wear and frictional forces, minimizing the risk of heat-related issues and allowing for standard, cost-effective snap-in bearing assembly without the risk of incorrect fitting, thereby enhancing the durability and operational reliability of the bearing assembly.
Implementation Method 1
The groove has a shaped portion which increases in diameter towards the lower end of the housing so as to accommodate flexing of a radially outer portion of the bearing ring when the strut is subject to lateral deflection forces
Data Source
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AI summary
A bearing assembly (2') comprising a housing (3') supporting first and second bearing ring portions (4, 4') with bearing surfaces to engage an inner tubular member (1') at axially spaced regions, characterised in that either: said bearing ring portions are provided by separate bearing rings (4') supported in the housing member (3') with bearing surfaces of different diameters; or said bearing ring portions are provided by a single bearing ring (4'') that is free to flex radially and is supported so that the second bearing ring portion is free to flex radially under load and its bearing surface than assumes a position with a greater diameter than that of the first bearing ring portion (4'').