Accessory Gearbox Cover Linkages for Vibration Isolation
Solution Overview
Problem
Aircraft engine accessory gearboxes face dynamic vibrations and resonances due to heavier accessories mounted on thin, light AGB covers, which can interfere with engine operating speeds and create structural concerns, with weight and envelope constraints limiting modifications to shift resonant frequencies.
Innovation Solution
The implementation of link members that dynamically couple accessory devices to each other independently of the AGB cover, allowing for mechanical interconnection and potential use of additional link members or dynamic absorbers to redistribute and dampen vibrations, thereby altering the frequency response and reducing loads on the cover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If accessories are mounted on the AGB cover, then the AGB can drive various engine accessories, but the AGB cover experiences dynamic vibrations and resonances that create structural concerns
Solution Approach 1:
The patent divides the accessory mounting system into two independent parts: the AGB cover and the accessory linkage system. The linkages are detachably coupled to the cover, allowing the accessories to be segmented and removed independently from the cover structure. This segmentation prevents vibrations from being permanently transmitted to the cover while maintaining the ability to mount various accessories.
Solution Approach 2:
The patent introduces linkages as intermediary components between the AGB cover and the accessories. These linkages act as a mediator that decouples the mechanical connection, allowing the cover to remain structurally isolated from accessory-induced vibrations while still enabling the drive function through the intermediate linkage mechanism.
2Weight of moving object
If the AGB cover is made thin and light, then weight constraints are satisfied, but the cover becomes prone to dynamic vibrations and resonances
Solution Approach 1:
The patent extracts the vibration-prone accessory mounting function from the AGB cover structure itself and places it in separate, detachable linkages. This extraction allows the cover to remain thin and light without bearing the harmful vibrational loads, as the linkages are removed or decoupled when not in use.
Solution Approach 2:
The patent employs dynamic linkages that can be adjusted or reconfigured based on operational needs. The linkages provide a dynamic solution where the mounting configuration can change, allowing the thin cover to adapt to different accessory configurations while maintaining structural integrity by isolating it from constant vibrational stress.
3Object-affected harmful factors
If modifications are made to the AGB cover to shift resonant frequencies, then vibration interference is reduced, but weight and envelope constraints are violated
Solution Approach 1:
Instead of changing the physical parameters of the AGB cover (which would increase weight), the patent changes the operational parameters by using detachable linkages that can be configured or removed to alter the dynamic characteristics of the accessory mounting system, thereby shifting resonant frequencies without modifying the cover itself.
Solution Approach 2:
The linkages serve as an intermediary system that can be independently tuned or adjusted to modify the vibrational characteristics. This allows resonant frequency shifting to be achieved through the linkage configuration rather than through cover modifications, preserving the lightweight design of the cover.
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 solution effectively reduces the overall load on the AGB cover by tuning the vibration frequency of coupled accessory devices, minimizing interference with engine operations and allowing for a lighter assembly by dissipating energy and counteracting resonant frequencies.
Implementation Method 1
a link member dynamically coupling the first accessory device to the second accessory device, the link member having an elongate body extending between a first end and a second end, the first end coupled to the first accessory device and the second end coupled to the second accessory device to mechanically interconnect the first and second accessory devices independent from the accessory gearbox cover
Implementation Method 2
a dynamic absorber disposed at a position along a length of the elongate body
Implementation Method 3
dissipating energy and counteracting resonant frequencies
Data Source
Figure 1
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Figure 3
AI summary
An accessory gearbox of an aircraft engine includes an accessory gearbox cover (40) mounted to the accessory gearbox. The accessory gearbox cover (40) has an outer surface (42) with accessory mounts (44) disposed thereon. A first accessory device (38a) is mounted to the accessory gearbox at a first mount (44) of the accessory mounts (44). A second accessory device (38b) is mounted to the accessory gearbox cover (40) at a second mount (44) of the accessory mounts (44). The second mount (44) is spaced apart on the accessory gearbox cover (40) from the first mount (44). A link member (56) dynamically couples the first accessory device (38a) to the second accessory device (38b). The link member (56) has an elongate body extending between a first end and a second end. The first end is coupled to the first accessory device (38a) and the second end is coupled to the second accessory device (38b) to mechanically interconnect the first and second accessory devices (38a, 38b) independent from the accessory gearbox cover (40).