Planet Carrier Flask Thinning to Prevent Gear Misalignment
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Solution Overview
Problem
The transmission of forces in a monobloc planet carrier for turbomachine gearboxes leads to misalignment of planet gears due to the uneven distribution of forces, as the geometry of the carrier is complex and lacks sufficient space to balance these forces effectively.
Innovation Solution
The planet carrier design includes a thinning around the orifices of the first flask to reduce its stiffness, which is compensated by the rigidity of the shaft portion, ensuring balanced stiffness on both sides of the bearings, thereby preventing misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the planet carrier uses a monobloc design with complex geometry to balance forces, then force transmission capability is improved, but manufacturing complexity and space requirements increase
Solution Approach 1:
The patent applies local quality by creating asymmetric thickness distribution in the planet carrier body. The first body portion surrounding the first bearing has greater thickness than the second body portion surrounding the second bearing, allowing each region to have optimized mechanical properties for its specific loading conditions without requiring complex overall geometry
2Ease of manufacture
If the planet carrier geometry is simplified, then manufacturing ease is improved, but force balancing capability deteriorates
Solution Approach 1:
The invention maintains manufacturing simplicity by using a relatively simple overall carrier structure with asymmetric bearing arrangements. The force balancing is achieved through local thickness variations rather than complex global geometry, preserving ease of manufacture while ensuring force balance stability
Solution Approach 2:
The patent deliberately introduces asymmetry in the carrier design by positioning the first and second bearings at different locations with different body thicknesses. This asymmetric configuration allows the carrier to balance uneven forces from the planet gears while maintaining a simple manufacturing process
3Stability of the object's composition
If the first flask thickness is reduced around orifices, then flexibility and force distribution are improved, but structural strength decreases
Solution Approach 1:
The patent applies local quality by selectively reducing thickness only in specific regions around the orifices in the first flask, while maintaining adequate thickness in other critical load-bearing areas. This localized thinning improves force distribution and flexibility without compromising overall structural strength
Data Source
AI summary
A planet carrier for a mechanical gearbox of a turbomachine, in particular for an aircraft, the planet carrier being formed in a single piece and comprising two annular flasks connected by material bridges and together defining housings configured to receive planet gears, the flasks comprising orifices for mounting the planet gears which are oriented axially and which open into the housings. One of the flasks can include at least one thinning around its orifices, the at least one thinning defining a minimum thickness of material in the axial direction which is less than a minimum thickness of the other flask around each of its orifices.