Planet Carrier Split-Shell Cage for Torque Load Distribution
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Solution Overview
Problem
In aircraft turbomachines with high bypass ratios, the existing planet carrier designs for speed reduction gears face challenges in efficiently distributing torque and maintaining structural integrity, often requiring bulky and heavy flanges for load support, which complicates assembly and operation.
Innovation Solution
The planet carrier design features a cage comprising two axially fixed shells with housings formed in both shells to support connecting elements, allowing for flexible ball joint connections and distributing forces evenly, enabling efficient torque transmission and reduced structural bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cage is made as a single monobloc structure, then the structural integrity is improved, but the manufacturing complexity and assembly difficulty increase when planet gears need to be mounted
Solution Approach 1:
The cage is divided into two separate shells (first shell and second shell) that can be manufactured independently and then assembled together. This segmentation allows planet gears to be mounted in each shell separately before final assembly, solving the assembly difficulty while maintaining structural integrity through the coordinated design of both shells with reinforcing ribs.
2Strength
If bulky flanges are added to the cage carrier to support reduction gear loads, then the load-bearing capability is improved, but the device weight and complexity increase
Solution Approach 1:
Instead of adding bulky flanges throughout the structure, reinforcing ribs are strategically placed in specific locations where loads are transmitted. The first and second shells include ribs positioned to receive and distribute loads from the planet gears and connecting elements, providing local strengthening without increasing overall device weight or complexity.
3Stability of the object's composition
If rigid connections are used between the cage and cage carrier, then the structural stability is improved, but the ability to accommodate misalignment and reduce stress concentrations decreases
Solution Approach 1:
The connection between the cage and cage carrier is made flexible rather than rigid. Connecting elements with ball joints are used to link the first and second shells to the cage carrier, allowing the connection to adapt to misalignments and reduce stress concentrations while maintaining structural stability through the coordinated rigid framework of the shells and reinforcing ribs.
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 design enhances the structural support and operational efficiency of the planet carrier, allowing for a more compact and lightweight construction while maintaining the necessary load-bearing capabilities, compatible with various reduction gear architectures.
Implementation Method 1
the fingers carrying ball joints through which cylindrical pins extend into the housings in the cage
Data Source
AI summary
A planet carrier for a speed reduction gear of a turbomachine has a main axis X and includes a cage carrier with an annular row of axial fingers around the axis X, which carry first connecting elements. The carrier further includes a cage having at its periphery housings and second connecting elements that are mounted in the housings and that cooperate with the first connecting elements to form connections between the cage carrier and the cage, which allow at least one degree of freedom. The cage comprises two shells that are axially fastened to each other and separated from each other by a plane. The housings are formed respectively in the shells.