Double-Row Concave Roller Bearing for Aircraft Flap Hinge
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Solution Overview
Problem
Bearing systems in aircraft, particularly those in trailing edge flap arrangements, face issues with debris ingress and lubricant loss due to seal failure and high stress zones leading to premature wear, as well as corrosion from environmental factors, which compromise their efficiency and longevity.
Innovation Solution
The implementation of a composite annular seal assembly with a sandwich seal design and hourglass roller bearings made from corrosion-resistant materials, featuring a unique concave exterior surface profile that reduces peak stress and a cage design to facilitate oscillatory movement while maintaining lubrication and preventing contaminants, along with a cage that limits roller skewing and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seals are positioned across the annular cavity to maintain lubricant and prevent debris ingress, then lubricant retention and contamination prevention are improved, but the seals become dislodged during operation and fail to function
Solution Approach 1:
The seal is divided into multiple segments or lips that can independently contact the raceways, allowing the seal to maintain its sealing function even if one segment becomes dislodged. This segmentation provides redundancy and maintains reliability while accommodating position variations.
Solution Approach 2:
The seal utilizes flexible material that can deform and adapt to the bearing's operational movements, maintaining continuous contact with the raceways to prevent lubricant loss and debris ingress while accommodating changes in seal position during operation.
2Ease of operation
If seals are made flexible to accommodate movement, then ease of operation is improved, but the seal glides over debris and sweeps debris into the annular cavity
Solution Approach 1:
The seal is designed with different regions having different properties - a rigid support structure provides stability while flexible sealing lips provide the necessary compliance. This local differentiation allows the seal to be flexible where needed for operation while maintaining debris exclusion capability where critical.
Solution Approach 2:
The seal lips are designed with specific curvature profiles that allow them to roll over debris particles rather than slide, reducing the tendency to sweep debris into the annular cavity while maintaining the flexibility needed for operational accommodation.
3Ease of manufacture
If typical hourglass rollers with constant radius of curvature are used, then manufacturing is simplified, but peak surface stress causes accelerated wear of bearing surfaces
Solution Approach 1:
The roller surface is designed with varying radius of curvature along its length - different sections have different curvature characteristics optimized for their specific functional requirements. This local differentiation reduces peak stress concentrations while maintaining manufacturability through standardized production techniques.
Solution Approach 2:
The roller geometry transitions from a constant radius of curvature to a variable radius of curvature profile, changing the geometric parameters along the roller length to optimize stress distribution and reduce peak surface stresses that cause accelerated wear.
4Power
If bearings operate at high loads, then power transmission is improved, but end-stress causes accelerated wear and premature failure
Solution Approach 1:
The bearing components are designed with modified geometric parameters including variable radius of curvature on rollers and optimized contact angles, which change the stress distribution characteristics to reduce end-stress while maintaining high load capacity for improved power transmission.
Solution Approach 2:
The bearing components utilize composite material structures or surface treatments that provide enhanced wear resistance and stress distribution capabilities, allowing the bearing to operate at high loads for extended durations without premature failure from end-stress wear.
Data Source
Figure A1
Figure B1
Figure A2A~A2B
AI summary
An edge flap arrangement (2) for an aircraft wing (1) includes a main flap element (2) and an actuator (7). A linkage arrangement supports the main flap (2). The linkage arrangement includes a drop hinge link arrangement (5). The drop hinge link arrangement (5) includes a fixed strut (5a) and a drop link (5c). The fixed strut (5a) and the drop link (5c) are pivotally connected by a hinge point (5b). The hinge point (5b) includes a double-row concave roller bearing. The double-row concave roller bearing includes an inner member, an outer member, and a plurality of concave rollers (115). Any combination of the inner member, the outer member, and the concave rollers are fabricated from CREN, Cronidur 30, XD15NW, 422 Stainless Steel, CRES, and/or 440C Stainless Steel. A prong cage is disposed between the inner member and the outer member. The prong cage includes a plurality of first rails and a plurality of second rails. Opposing pairs of first rails and second rails define a plurality of pockets.