Generator Input Shaft with Internal Oil Bore for Spline Cooling
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Solution Overview
Problem
Conventional input shafts for generators lack effective lubrication and cooling mechanisms, particularly in integrating with airframe mounted accessory drives (AMAD) using a shared oil system.
Innovation Solution
The input shaft incorporates an internal bore for fluid flow, with orifices leading to the exterior surface to lubricate and cool the gearbox spline, featuring a specific ratio of spline lengths and diameters for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional input shafts are used without internal bore lubrication, then the structure is simpler, but lubrication and cooling efficiency deteriorates
Solution Approach 1:
The input shaft is segmented into functional zones with the internal bore creating separate lubrication channels. Oil is delivered through specific orifices at strategic locations to lubricate the gearbox spline interface, separating the lubrication function from the structural function of the shaft.
Solution Approach 2:
The lubrication system is nested within the input shaft structure itself. The internal bore and orifices are integrated into the shaft body, allowing the shaft to serve dual purposes: mechanical torque transmission and lubrication delivery, eliminating the need for separate external lubrication components.
2Reliability
If oil delivery system is added to conventional input shaft, then cooling and lubrication improves, but manufacturing complexity increases
Solution Approach 1:
The lubrication and cooling functions are merged with the input shaft structure. The internal bore and orifices are integrated directly into the shaft manufacturing process, combining what would traditionally be separate components (shaft and lubrication system) into a single unified part.
Solution Approach 2:
The input shaft becomes a multi-functional component that simultaneously performs mechanical torque transmission and fluid delivery for lubrication and cooling. This universal design eliminates the need for separate dedicated lubrication components, simplifying the overall system despite the enhanced functionality.
3Reliability
If gearbox spline axial length ratio is optimized, then lubrication efficiency improves, but design constraints increase
Solution Approach 1:
The axial length of the gearbox spline is optimized to a specific ratio (0.16 to 1 relative to the main shaft length) to ensure proper oil distribution and lubrication coverage. This parameter optimization ensures that oil delivered through the orifices effectively reaches all contact surfaces of the spline interface.
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
Enhances lubrication and cooling efficiency, improving the operational reliability and durability of the input shaft in generator systems.
Implementation Method 1
an internal bore configured for fluid flow through the annular main shaft
Implementation Method 2
for flow of fluid from the internal bore to the exterior surface for cooling and lubrication
Implementation Method 3
for flow of fluid from the internal bore to the exterior surface for cooling and lubrication
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An input shaft (100) includes an annular main shaft (102) extending along a longitudinal axis with an internal bore (104) configured for fluid flow through the annular main shaft (102). A generator spline (106) is included on an exterior surface (108) of a first end (110) of the main shaft (102). A gearbox spline (112) is included on an exterior surface (114) of a second end (116) of the main shaft (102) opposite the first end (110). At least one orifice (118) is defined through the main shaft (102) from the internal bore (104) to the exterior surface (114) of the second end (116) of the main shaft (102) for flow of fluid from the internal bore (104) to the exterior surface for cooling and lubrication.