Additive Gear Rim Structure for Uniform Bearing Stiffness
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Solution Overview
Problem
Current geared architectures in gas turbine engines face challenges with centrifugal loads on planet bearings, particularly at higher loads and larger diameters, where radial stiffness variations at axial lightening apertures affect performance.
Innovation Solution
The use of additive manufacturing for the inner rim of gear components, allowing for a lightweight, thick inner portion with tailored stiffness and material selection suitable for high-temperature environments, such as alloys like 625, 718, and 230, which can be laser welded or integrated with dissimilar materials via bond layers, to enhance bearing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If axial lightening apertures are added to gear rims to reduce weight, then weight is reduced, but radial stiffness becomes non-uniform affecting performance
Solution Approach 1:
The patent applies local quality by creating a non-uniform rim structure where the inner portion has different properties than the outer portion. The additive manufactured inner rim provides localized stiffness enhancement at the bearing support zone while maintaining weight reduction through the overall lightened structure. This resolves the contradiction by making different parts of the rim have different qualities - the inner portion is thicker and stiffer for bearing support, while the outer portion remains lighter.
2Stability of the object's composition
If conventional manufacturing methods are used for gear rims, then structural uniformity is maintained, but weight reduction opportunities are lost
Solution Approach 1:
The patent segments the gear rim into two distinct manufacturing zones: an outer portion manufactured by conventional subtractive methods and an inner portion manufactured by additive manufacturing. This segmentation allows each zone to be optimized for its specific function - the outer portion maintains conventional structural properties while the inner portion leverages additive manufacturing capabilities to provide targeted weight reduction and stiffness enhancement at the bearing support location.
3Weight of moving object
If additive manufacturing is used for the inner rim to reduce weight, then weight is reduced and stiffness is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent merges two different manufacturing processes - additive manufacturing for the inner rim and conventional subtractive manufacturing for the outer rim - into a single integrated gear component. This combining approach allows the complex additive manufactured inner portion to be directly integrated with the simpler outer portion, creating a unified structure that achieves weight reduction and stiffness enhancement without requiring separate assembly operations or complex tooling for multiple components.
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
This approach reduces weight while maintaining uniform stiffness, improving bearing performance and reducing the need for bonding, thereby enhancing the efficiency and durability of gear systems in gas turbine engines.
Implementation Method 1
The inner portion (104B) of the rim (104) is manufactured by an additive manufacturing process
Implementation Method 2
The additive manufactured inner portion (104B) is laser welded to the outer portion (104A) of the rim (104)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A gear (68) includes a multiple of gear teeth (100) that extend from an outer portion (104A) of a rim (104) about an axis and an inner portion (104B) of the rim (104) about the axis, the inner portion (104B) of the rim (104) additive manufactured.