Annular Generator Input Shaft With Internal Oil Cooling
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Solution Overview
Problem
Conventional input shafts for generators lack effective integration with airframe mounted accessory drives and do not adequately address cooling and lubrication needs, leading to suboptimal performance.
Innovation Solution
An input shaft design featuring an annular main shaft with internal fluid flow, generator and gearbox splines, strategically located orifices for fluid flow, a shear section, and o-ring grooves for enhanced lubrication and cooling, allowing for efficient torque transfer and rotational driving of generators and gearboxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional input shaft design is used, then structural simplicity is maintained, but cooling and lubrication effectiveness is insufficient
Solution Approach 1:
The input shaft is segmented into multiple functional zones: a drive section with generator and gearbox splines, a shear section with reduced wall thickness, and a fluid distribution system with multiple orifices. This segmentation allows each section to be optimized for its specific function while collectively improving overall cooling and lubrication effectiveness without excessive complexity
Solution Approach 2:
An oil gallery system acts as an intermediary between the external lubrication source and critical contact surfaces. Fluid is delivered through the internal bore and distributed via orifices to the shear section and spline interfaces, providing effective lubrication and cooling without requiring direct external access to these internal surfaces
2Strength
If uniform wall thickness is used throughout the shaft, then manufacturing is simplified, but torque transfer and shear resistance are suboptimal
Solution Approach 1:
The shaft employs variable wall thickness with a shear section having reduced thickness between the generator and gearbox splines. This local modification concentrates material where strength is needed (at the spline interfaces) while reducing material where less strength is required, optimizing torque transfer and shear resistance without uniformly increasing complexity throughout the entire shaft
Solution Approach 2:
The design transitions from a simple cylindrical geometry to a more complex three-dimensional form with varying wall thickness and internal fluid passages. This dimensional complexity enables optimized stress distribution and fluid flow paths that improve strength and cooling performance
3Reliability
If no internal fluid flow paths are provided, then the shaft structure remains simple, but cooling and lubrication of internal surfaces is inadequate
Solution Approach 1:
The internal bore serves multiple functions: it provides structural support as part of the shaft anatomy, acts as a fluid conduit for lubrication and cooling, and enables weight reduction through material removal. This multi-functionality improves lubrication effectiveness without adding separate dedicated components that would increase complexity
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 design provides superior lubrication and cooling, enabling improved torque transfer and rotational driving capabilities, enhancing the performance and reliability of generators and gearboxes.
Implementation Method 1
an internal bore configured for fluid flow through the annular main shaft
Implementation Method 2
At least one orifice is defined through the main shaft from the internal bore to the exterior surface of the second end of the main shaft for flow of fluid from the internal bore to the exterior surface for cooling and lubrication
Data Source
AI summary
An input shaft includes an annular main shaft extending along a longitudinal axis with an internal bore configured for fluid flow through the annular main shaft. A generator spline is included on an exterior surface of a first end of the main shaft. A gearbox spline is included on an exterior surface of a second end of the main shaft opposite the first end. At least one orifice is defined through the main shaft from the internal bore to the exterior surface of the second end of the main shaft for flow of fluid from the internal bore to the exterior surface for cooling and lubrication.