Accessory Gearbox Cover Linking Member for Vibration Decoupling
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Solution Overview
Problem
Aircraft engine accessory gearboxes face dynamic vibrations and resonances due to mounted accessories, which interfere with engine operating speeds and pose structural concerns, with weight and envelope constraints limiting modifications to address these issues.
Innovation Solution
A planar linking member dynamically couples accessory devices to each other, independent of the gearbox cover, shifting their vibration frequency and providing mechanical interconnection to reduce resonance interference.
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 interfere with engine operating speeds
Solution Approach 1:
A planar linking member is introduced as an intermediary component to mechanically connect multiple accessory devices to each other, creating a coupled mass that vibrates at a different frequency from the AGB cover, thereby mediating the harmful vibration transmission to the cover
Solution Approach 2:
Multiple accessory devices are merged into a single coupled mass through the planar linking member, causing them to vibrate together at a unified frequency that is distinct from the AGB cover's resonant frequencies, reducing vibration interference
2Object-affected harmful factors
If the AGB cover structure is modified to shift resonant frequencies, then vibration interference can be reduced, but weight and envelope constraints limit the changes that can be made
Solution Approach 1:
The vibration control function is segmented from the AGB cover structure itself and transferred to a separate planar linking member that connects accessory devices, allowing the cover to remain lightweight while still achieving vibration frequency separation
3Object-affected harmful factors
If the AGB cover structure is modified to shift resonant frequencies, then vibration interference can be reduced, but envelope constraints limit the changes that can be made
Solution Approach 1:
The planar linking member serves as a space-efficient intermediary that achieves vibration frequency separation without requiring modifications to the AGB cover's envelope, as it connects accessories directly to each other rather than modifying the cover structure
4Adaptability or versatility
If accessories are mounted on the AGB cover, then engine accessories can be driven, but structural concerns arise due to vibrations and resonances
Solution Approach 1:
Multiple accessory devices are merged into a coupled mass through the planar linking member, creating a more stable vibration pattern at a different frequency, thereby improving structural reliability while maintaining the ability to mount various accessories
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 impact of accessory vibrations on the engine by synchronizing their frequencies, thereby alleviating structural concerns and allowing for lighter engine components.
Implementation Method 1
AGB covers are therefore prone to dynamic vibrations and/or resonances during operation of the engine. In addition, certain accessories, such as generators, can induce additional vibrations in the AGB cover due to their own operating unbalances.
Implementation Method 2
The frequencies generated by the vibrations and/or resonances can interfere with engine operating speeds and create structural concerns.
Data Source
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AI summary
An accessory gearbox of an aircraft engine includes a cover (40) that defines a centrally extending axis (A) and has an outer surface (42) with accessory mounts (44) disposed thereon. First and second accessory devices (38a, 38b) are mounted to the gearbox at first and second mounts (44) spaced apart on the cover (40). A planar linking member (56) dynamically couples the first accessory device (38a) to the second accessory device (38b). The linking member (56) extends transversally relative to the axis (A) and has a first side (58) opposite a second side with a first opening (64) extending therethrough. The first opening (64) is aligned and matingly receiving at least a portion of the first accessory device (38a) therethrough. The linking member (56) has a second opening (64) extending therethrough. The second opening (64) is aligned and matingly receiving at least a portion of the second accessory device (38b) therethrough. The linking member (56) mechanically interconnects the first and second accessory devices (38a, 38b) independently from the cover (40).