Fan Disc Assembly Tapered Interface Radial Load Transfer
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Solution Overview
Problem
Fan disc assemblies in gas turbine engines face issues with radial loads and movement causing wear on splines, and existing connection methods require heating or cooling for assembly and disassembly, which is inefficient and can lead to damage during maintenance.
Innovation Solution
The use of tapered surfaces on the bore and shaft aft sections allows for secure positioning and radial load transfer without the need for heating or cooling, enabling easy separation during disassembly and reducing the risk of damage to the fan disc.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If interference fit is used to connect fan disc to shaft, then secure positioning and radial load transfer are achieved, but heating or cooling is required for assembly and disassembly which is inefficient and can cause damage
Solution Approach 1:
The patent changes the geometric parameters of the connection interface by introducing tapered surfaces with specific angles (typically 5-15 degrees) on both the shaft and fan disc. This parameter change allows the connection to be secured through mechanical interference of the tapered surfaces, eliminating the need for thermal expansion or contraction methods while maintaining strong radial load transfer capability.
Solution Approach 2:
The connection interface is segmented into distinct functional zones: the tapered surfaces for positioning and load transfer, and the splines for torque transmission. This segmentation allows each element to perform its specific function optimally without interfering with other connection requirements, enabling easy disassembly by simply reversing the taper engagement.
2Strength
If conventional connection methods are used, then secure mounting is achieved, but radial loads cause wear on spline teeth
Solution Approach 1:
The connection interface is segmented into distinct functional zones: the tapered surfaces for positioning and load transfer, and the splines for torque transmission. This segmentation allows each element to perform its specific function optimally without interfering with other connection requirements, enabling easy disassembly by simply reversing the taper engagement.
Solution Approach 2:
The patent applies local quality by giving different functional characteristics to different parts of the connection interface. The tapered surfaces are designed with specific angles and surface qualities optimized for load transfer and positioning, while the spline teeth are designed with different geometries optimized for torque transmission. This localized optimization ensures radial loads are borne by the tapered surfaces rather than the splines, preventing wear.
3Strength
If heating or cooling is applied for assembly, then interference fit is formed, but it is difficult to apply heating or cooling at the aft section location
Solution Approach 1:
The patent changes the geometric parameters of the connection interface by introducing tapered surfaces with specific angles (typically 5-15 degrees) on both the shaft and fan disc. This parameter change allows the connection to be secured through mechanical interference of the tapered surfaces, eliminating the need for thermal expansion or contraction methods while maintaining strong radial load transfer capability.
4Ease of repair
If fan disc is disconnected during maintenance, then maintenance can be performed, but damage may occur to the fan disc
Solution Approach 1:
The patent changes the geometric parameters of the connection interface by introducing tapered surfaces with specific angles (typically 5-15 degrees) on both the shaft and fan disc. This parameter change allows the connection to be secured through mechanical interference of the tapered surfaces, eliminating the need for thermal expansion or contraction methods while maintaining strong radial load transfer capability.
Data Source
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AI summary
The present disclosure concerns a fan disc assembly, and in particular a fan disc assembly for a gas turbine engine. Example embodiments disclosed include a fan disc assembly (1400) for a gas turbine engine, comprising: a fan disc (1401) with a central bore comprising a bore forward section (1404), a bore aft section (1406) and a bore spline (1405) between the bore forward and aft sections; a shaft (1402) mounted within the central bore of the fan disc (1401), the shaft (1402) comprising a shaft forward section (1407) connected to the bore forward section (1404), a shaft aft section (1409) connected to the bore aft section (1406) and a shaft spline (1408) between the forward and aft sections and mating with the bore spline (1405); wherein the bore aft section (1406) comprises a tapered surface mating against a corresponding tapered surface on the shaft aft section (1409).