Clevis Joint Assembly Using Interference-Fit Pins and Bearing Inserts
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Solution Overview
Problem
Current gimbal joints in gas turbine engines face challenges in withstanding high pressures, temperatures, and vibrations, requiring skilled personnel for repair or replacement, and have high manufacturing and installation costs due to inadequate welding methods.
Innovation Solution
A joint assembly design featuring a ring with pins that utilize an interference fit and electron beam or laser beam welding, allowing for efficient load transfer and reducing the heat-affected zone, along with replaceable bearing inserts made from different materials for improved durability and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional welding methods are used to connect pins, bellows and flanges, then the manufacturing process is simple, but the welds fail to adequately resist stresses from high pressures, temperatures, and vibrations
Solution Approach 1:
The patent replaces traditional mechanical welding connections with an interference fit mechanism. The pin features a shaft portion with a diameter that creates interference with the ring aperture, generating frictional forces that resist applied loads. This mechanical interference fit substitutes for the inadequate weld connections, providing superior stress resistance without requiring complex welding procedures.
Solution Approach 2:
The patent employs a hybrid connection system combining interference fit (mechanical press fit) with strategic welding at specific locations. The interference fit provides the primary load-bearing mechanism, while limited welding at the head portion to the ring provides additional anchoring. This composite approach leverages the strengths of both connection methods while avoiding the weaknesses of relying solely on welding.
2Strength
If welding is used to connect pins to the ring, then the connection is strong, but the heat-affected zone weakens the material properties at the load path
Solution Approach 1:
The patent applies local quality by creating different connection characteristics at different locations of the pin. The shaft portion utilizes interference fit without heat-affected zones, while the head portion receives welding only where necessary to anchor it to the ring. This localized approach ensures that the critical load-bearing shaft portion maintains full material properties, while welding is applied only where it provides additional benefit without compromising the load path.
Solution Approach 2:
The pin is segmented into functionally distinct portions: a shaft portion that interfaces with the ring aperture through interference fit and carries the primary load, and a head portion that is welded to the ring for anchoring. This segmentation allows each portion to be optimized for its specific function, with the shaft portion free from heat-affected zone degradation and the head portion providing welded attachment.
3Strength
If the pin is designed to handle all loads through welding, then the connection is robust, but the pin requires larger dimensions and increased weight
Solution Approach 1:
The patent replaces the welding-based load transfer system with an interference fit-based mechanical system. The interference fit generates frictional forces along the shaft portion that efficiently transfer loads between the pin and ring. This mechanical load transfer mechanism is more efficient than welding, allowing for a smaller, lighter pin design while maintaining or improving load capacity.
Solution Approach 2:
The patent changes the load transfer mechanism from thermal (welding) to mechanical (interference fit friction). By utilizing the frictional forces generated by the interference between the shaft portion diameter and ring aperture, the system achieves superior load transfer efficiency. This parameter change allows for optimization of the pin dimensions, resulting in a lighter component that can handle the same or higher loads.
4Device complexity
If bearings are integrated into the clevis structure, then the joint assembly is simpler, but the clevis material must accommodate both structural and bearing requirements
Solution Approach 1:
The patent segments the bearing function from the clevis structure by using separate bearing inserts. These inserts are pressed into the clevis and provide the bearing surface for the pin shaft portion. This segmentation allows the clevis to be manufactured from materials optimized for structural requirements, while the bearing inserts are made from materials optimized for bearing performance such as bronze or other low-friction materials.
Solution Approach 2:
The patent employs composite material construction by combining the clevis (made from structural material) with bearing inserts (made from bearing-optimized material). This composite approach allows each component to be made from the most suitable material for its specific function, achieving both structural integrity and bearing performance without compromising material selection flexibility.
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 enhances the robustness and reliability of the joint assembly by displacing the heat-affected zone away from the load path, enabling a lighter, more efficient design with reduced maintenance needs and lower costs.
Implementation Method 1
The shaft portion of each pin is coupled to the ring by a corresponding interference fit
Implementation Method 2
the head portion of each pin is coupled to the ring by a corresponding weld
Implementation Method 3
The weld between the head portion and the ring includes an electron beam weld or a laser beam weld
Implementation Method 4
The weld between the head portion and the ring includes an electron beam weld or a laser beam weld
Data Source
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AI summary
A joint assembly (100) for joining a first component (102) to a second component (104) is provided. The joint assembly (100) includes a first clevis (110) including first clevis apertures (216) and a second clevis (120) including second clevis apertures (226). The joint assembly (100) further includes first and second bearing inserts (218, 228) fixedly coupled to the first and second clevises (110, 120), respectively. The joint assembly (100) further includes a ring (130) surrounding the first and second clevises (110, 120) and including a plurality of ring apertures (232). The joint assembly (100) further includes a plurality of pins (240, 602, 702) received within the corresponding ring aperture (232). Each pin (240, 602, 702) includes a head portion (242, 606, 706) and a shaft portion (244, 604, 704) extending from the head portion (242, 606, 706). The shaft portion (244, 604, 704) is coupled to the ring (130) by a corresponding interference fit (312, 612). The shaft portion (244, 604, 704) is coupled to the corresponding first or second bearing inserts (218, 228) by a corresponding clearance fit (314, 404, 614) such that the shaft portion (244, 604, 704) is rotatable relative to the corresponding first or second bearing inserts (218, 228).