Annular Bearing Spring for Epicyclic Gear Shaft Alignment
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Solution Overview
Problem
Epicyclic gear systems in gas turbine engines face challenges in accommodating relative movement between components, leading to potential misalignment and uneven load sharing, which can cause gear degradation and reduced system performance.
Innovation Solution
A housing assembly for the epicyclic gear system incorporating a bearing and an annular spring positioned between the bearing and the housing, allowing for relative movement and accommodating deflection to maintain alignment and even load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid bearing assembly is used to maintain precise alignment, then alignment precision is improved, but the system cannot accommodate relative movement between components leading to misalignment and uneven load sharing
Solution Approach 1:
The bearing assembly is transformed from a rigid static structure to a dynamic compliant structure by incorporating an annular spring between the bearing and housing. This allows the bearing to dynamically adjust its position to accommodate relative movement between gear components while maintaining alignment precision through the spring's elastic deformation.
Solution Approach 2:
The mechanical properties of the bearing assembly are changed by introducing a compliant element (annular spring) that alters the stiffness parameter. The spring provides a controlled degree of flexibility, allowing the system to adapt to dimensional variations and thermal expansion while maintaining operational precision.
2Stability of the object's composition
If components are rigidly fixed to maintain structural stability, then structural stability is improved, but uneven load distribution occurs leading to bearing wear and reduced system life
Solution Approach 1:
Instead of making the entire structure compliant, only the local bearing assembly is made compliant through the annular spring. This localized compliance allows the bearing to self-adjust and distribute loads evenly while the rest of the gear system maintains its structural stability and rigidity.
Solution Approach 2:
The annular spring acts as a cushioning element that anticipates and absorbs dimensional variations, thermal expansion, and load fluctuations before they can cause misalignment or uneven bearing loads. This preemptive compliance protection prevents wear and extends bearing life.
3Adaptability or versatility
If the bearing assembly is made compliant to accommodate movement, then adaptability is improved, but structural rigidity decreases potentially affecting gear meshing precision
Solution Approach 1:
The bearing assembly employs dynamic compliance through the annular spring, which provides just enough flexibility to accommodate thermal expansion and dimensional variations. The spring's controlled compliance maintains structural rigidity while allowing necessary movements, preventing both over-rigidity (which causes misalignment) and over-compliance (which would affect gear meshing 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
The solution effectively minimizes fore-to-aft misalignment of the gear shaft, enhances bearing life by ensuring even load distribution, and improves the overall performance and longevity of the epicyclic gear system.
Implementation Method 1
an annular spring disposed over at least a portion of the bearing... effecting flexion of the annular spring responsive to relative movement between the bearing and gear shaft
Data Source
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AI summary
A housing assembly for an epicyclical gear system comprises a housing, a cylindrical gear shaft, a gear, and a bearing assembly. The housing defines a gear shaft pocket having a cylindrical wall. The cylindrical gear shaft has one end portion disposed within the gear shaft pocket coaxially with the cylindrical wall. At least one gear is carried by the gear shaft. The bearing assembly comprises a bearing disposed over at least a portion of the end portion of the gear shaft; and an annular spring disposed over at least a portion of the bearing.