Sliding Bearing Pivot Hole Layout for Planetary Gear Alignment
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Solution Overview
Problem
Epicyclic gear trains in turbine engines experience misalignment of planetary pinion teeth due to non-uniform deformations caused by tangential and radial displacements, leading to reliability and efficiency issues in sliding bearings.
Innovation Solution
The introduction of a pivot design with holes in a specific angular sector of the annular wall, providing increased flexibility and balancing deformations between upstream and downstream sides, enhancing the alignment of planetary pinion teeth with the gear train axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pivot is made rigid to maintain structural integrity, then strength is improved, but misalignment of planetary pinion teeth occurs due to non-uniform deformations
Solution Approach 1:
The pivot incorporates holes distributed non-uniformly in the angular direction, creating local variations in flexibility. The holes are concentrated in specific angular sectors rather than being uniformly distributed, allowing different regions of the pivot to have different degrees of flexibility to compensate for non-uniform deformations under tangential and radial loads
2Manufacturing precision
If holes are added to increase flexibility and reduce mass, then alignment improves and mass decreases, but structural strength may be compromised
Solution Approach 1:
The invention carefully controls the parameters of the holes (size, distribution, angular positioning) to achieve the desired balance between flexibility and strength. The holes are distributed in a specific angular pattern that provides sufficient flexibility for alignment while maintaining overall structural integrity under operational loads
3Manufacturing precision
If the pivot is made more flexible to accommodate deformations, then alignment improves, but the pivot may deform excessively under load
Solution Approach 1:
By creating local variations in flexibility through non-uniform hole distribution, the pivot achieves balanced deformations across different regions. This prevents excessive deformation in any single area while still allowing sufficient flexibility for proper alignment of the planetary pinion teeth
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 improves the radial alignment of teeth, reduces mass, and maintains the structural integrity of the gear train by distributing circumferential deformation, thereby enhancing the reliability and efficiency of the epicyclic gear train.
Implementation Method 1
by making holes in a given angular sector, more flexibility can be provided in this angular sector of the pivot compared to the rest of the pivot, which allows greater local deformation of the pivot
Implementation Method 2
Tangential displacements, due to applied torques, and/or radial displacements, due to centrifugal force, were observed on pivots
Data Source
AI summary
A pivot for a sliding bearing of an epicyclic train includes an annular wall delimiting an axial passage, the annular wall including a first and a second annular groove opening axially in opposite directions and each defined by two coaxial inner and outer annular branches formed at the axial ends of the annular wall. The pivot also includes a plurality of first holes opening at a first end into the first annular groove and at a second opposite end into the second annular groove, these holes being made over an angular sector of between 5° and 330°.