Asymmetrical Linkage Head for Short Clevis Engagement
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Solution Overview
Problem
Existing linkage apparatuses for gas turbine engines face challenges in engaging short-shanked clevises due to size limitations, requiring additional fabrication processes that reduce load-carrying capability and create stress concentrations.
Innovation Solution
A low-profile linkage apparatus with a self-lubricating bearing assembly featuring a polytetrafluoroethylene (PTFE) or PFOA-based liner system, integrated into a spherical plain bearing assembly, which is staked into a socket head with a truncated arcuate outer surface, allowing for proper engagement with short-shanked clevises without additional machining and enhancing load-carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the head portion is modified by machining or milling a flat in an arcuate outer surface to reduce thickness, then the head can properly engage the clevis, but this creates local stress concentrations and reduces the load carrying capability
Solution Approach 1:
The patent applies asymmetry by creating a low-profile head configuration where the arcuate outer surface is selectively removed or modified on one side to create an asymmetric shape. This allows the head to engage short-shanked clevises while maintaining structural integrity through strategic material removal rather than uniform thinning, thus resolving the contradiction between engagement capability and load carrying strength.
Solution Approach 2:
The patent implements local quality by modifying only specific portions of the arcuate outer surface rather than uniformly reducing the head thickness. The flat or reduced-thickness region is localized to areas where engagement with the clevis is required, while other portions of the head maintain their original thickness and strength characteristics, thereby preserving overall load carrying capability.
2Volume of moving object
If short-shanked flanges or uprights are used in the clevis, then the clevis structure is more compact, but the shaft engaged in the bearing cannot properly engage the bore defined in the clevis flanges
Solution Approach 1:
The asymmetric head design allows the bearing assembly to be positioned at an optimized location relative to the shaft centerline. This asymmetric configuration enables proper shaft-bore engagement even when the clevis has short shanked flanges, because the head can extend further in the direction needed to reach the bore while maintaining a compact overall profile.
Solution Approach 2:
The patent resolves the engagement problem by utilizing the radial dimension of the head portion. Instead of simply reducing head thickness in one direction, the design allows the head to maintain adequate radial extent to engage the bore properly, while reducing thickness only in the axial direction where compactness is needed. This dimensional differentiation allows both compact clevis integration and proper shaft engagement.
3Ease of operation
If additional fabrication processes such as machining or milling are applied to the head, then the head thickness is reduced for proper engagement, but this requires additional fabrication processes and reduces load carrying capability
Solution Approach 1:
The low-profile head configuration with asymmetric arcuate surface modification is designed and manufactured as an integral feature of the head portion itself, rather than requiring subsequent machining or milling operations. The asymmetric shape is built-in during the primary manufacturing process, eliminating the need for additional fabrication steps and reducing overall device complexity while maintaining engagement compatibility.
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 enables the linkage apparatus to support high static radial loads up to 20,000 lbs while reducing stress concentrations and eliminating the need for additional fabrication, thus improving engagement with short-shanked clevises and maintaining high load-carrying capability.
Implementation Method 1
A self-lubricating liner is disposed between the inner engagement surface of the outer member and the outer engagement surface of the inner member
Implementation Method 2
the self-lubricating liner is fabricated from a polytetrafluoroethylene ("PTFE") bonded with a thermoset resin
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A high-cycle, short range-of-motion linkage apparatus is provided for actuating a positioning device. The linkage apparatus includes a pivot member (26) having a head portion configured to receive by plastic deformation a bearing assembly (10) therein. The head portion defines a bore therein having a substantially cylindrical inner surface that defines an inner diameter having a first center point (XI). A stem (30) having a central axis extends from the pivot member along the central axis in a first direction. The head portion further defines a truncated arcuate (427A-427D) outer surface (427), a portion of which defines a radius of curvature (R1-R3) and a second center point (X2). The second center point is offset from the first center point in the first direction and a distance D3 between the first center point and the second center point, measured along the central axis, is in the range of up to about 33% of the radius of curvature (R1-R3).