Integral Flexured Planetary Carrier for Aircraft Gear Alignment
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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 specialized bearings, and providing dual flexibility to maintain alignment and reduce weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional nonintegral carriers with fasteners are used, then assembly flexibility is improved, but joint failure risk increases and reliability deteriorates
Solution Approach 1:
The patent merges the carrier body and carrier posts into a single integral structure, eliminating fasteners and joints that could fail. The integral carrier is formed as one monolithic piece, combining what were previously separate components (carrier ring and carrier posts) into a unified structure that cannot experience joint failure between these elements.
Solution Approach 2:
The integral carrier structure serves multiple functions simultaneously: it provides structural support, maintains alignment, and eliminates the need for separate fastening components. The flexured carrier posts provide both structural support and compliance functionality in a single integrated element.
2Stability of the object's composition
If traditional carriers rely on stiffness to counteract planet gear loads, then structural stability is improved, but weight increases
Solution Approach 1:
The patent changes the mechanical parameter of the carrier posts from rigid/stiff to flexured/compliant. The flexured carrier posts have controlled flexibility that allows them to deflect under load while maintaining structural integrity. This parameter change enables the carrier to absorb planet gear loads through elastic deformation rather than requiring excessive stiffness, thereby reducing weight.
Solution Approach 2:
The patent introduces dynamic compliance into the carrier structure through flexured posts that can flex and deflect under varying loads. Instead of a static rigid structure, the carrier now has dynamic flexibility that allows it to adapt to load conditions, absorbing energy through controlled deformation while maintaining stability.
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 extracts and removes the spherical roller bearings from the system, replacing them with an alternative alignment mechanism. The flexured carrier posts themselves provide the alignment function that previously required separate bearing components, eliminating the complexity and cost of spherical roller bearings while maintaining proper planet gear alignment.
Solution Approach 2:
The flexured carrier posts provide self-aligning capability through their inherent flexibility and compliance. The posts naturally deflect to accommodate manufacturing tolerances and load variations, providing alignment functionality without requiring additional specialized bearings or complex adjustment mechanisms.
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 results in a lighter, more reliable, and cost-effective planetary gear system with reduced joint wear and material requirements, achieving proper alignment without the need for spherical bearings and increased stiffness, thus enhancing the overall performance and efficiency of the gear system.
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.