Integral Flexured Planetary Carrier for Lighter Aircraft Gearboxes
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Solution Overview
Problem
Current planetary gear systems in aerospace applications are heavy, complex, and costly due to reliance on nonintegral carriers and spherical roller bearings, which increase the risk of joint failure and require additional material for stiffness, leading to higher weight and complexity.
Innovation Solution
The implementation of an integral carrier with flexured carrier posts and flexured roller races that absorb loads through cantilevered motion, reducing the need for fasteners and spherical bearings, and allowing for lighter, more reliable designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional nonintegral carriers with fasteners are used, then assembly is simplified, but reliability decreases due to increased risk of joint failure
Solution Approach 1:
The patent merges the carrier body and carrier posts into a single integral structure, eliminating the need for fasteners and joints. This combining of previously separate components into one monolithic piece directly improves reliability by removing joint failure risks while simplifying the overall structure.
2Weight of moving object
If traditional carriers rely on stiffness to counteract planet gear loads, then structural stability is maintained, but weight increases due to additional material required
Solution Approach 1:
The patent introduces dynamic flexibility to the carrier structure through flexured posts that can elastically deform under load. Instead of relying on static stiffness from additional material, the structure uses controlled elastic deformation to absorb and distribute planet gear loads, significantly reducing carrier weight while maintaining load-bearing capacity.
Solution Approach 2:
The patent changes the mechanical parameter of the carrier from rigid stiffness to flexible compliance. By designing posts with specific flexural properties, the structure can dynamically adjust to loads through elastic deformation, replacing the need for heavy stiffening material while maintaining structural integrity.
3Manufacturing precision
If spherical roller bearings are used to ensure planet gear alignment, then alignment precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the carrier structure to self-align planet gears through the elastic deformation of flexured posts. The posts naturally adjust their position under load to maintain proper gear meshing, eliminating the need for external spherical roller bearings and their associated complexity while preserving alignment precision.
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 solution reduces the weight, volume, and cost of planetary gear systems while enhancing reliability by distributing loads through dual flex modes, maintaining proper alignment without the need for additional stiffness or expensive bearings.
Implementation Method 1
The cantilevered ends of the flexured roller races experience cantilevered motion to absorb loads from the planet gears
Data Source
AI summary
A drivetrain for an aircraft includes an engine, a driveshaft receiving rotational energy from the engine and a gearbox including a planetary gear system receiving rotational energy from the driveshaft. The planetary gear system includes a sun gear, planet gears, a ring gear and an integral carrier forming flexured carrier posts. Each flexured carrier post supports a respective one of the planet gears and has a fixed proximal end and a cantilevered distal end. The planetary gear system includes flexured roller races, each having a fixed end and a cantilevered end. The fixed end of each flexured roller race is coupled to the cantilevered distal end of a respective flexured carrier post. The planet gears engage with the flexured roller races to rotate about the flexured carrier posts. The cantilevered ends of the flexured roller races experience cantilevered motion to absorb loads from the planet gears.