Aircraft Engine Mount Layout for Torque Roll Vibration Isolation
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Solution Overview
Problem
There is a compromise in designing aircraft engine mounting arrangements that require high stiffness to limit engine deflection under high gravity loads while also needing low stiffness to minimize torque and vibration transmission, which existing technologies have not effectively addressed.
Innovation Solution
The solution involves a compounded turboshaft engine mounting arrangement using one-degree-of-freedom links with varying stiffness, where a first set of links has a high stiffness for deflection restriction and a second set with lower stiffness for torque isolation, utilizing elastomeric bushings to manage reaction forces and decouple torque roll mode from other degrees of freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high mount stiffness is used to limit engine deflection under high gravity loads, then engine deflection is reduced, but torque and vibration transmission to the aircraft structure increases
Solution Approach 1:
The engine mounting system is divided into two distinct sets of links: a first set of one-degree-of-freedom links with high stiffness for limiting engine deflection, and a second set of links with low stiffness for isolating torque and vibration. This segmentation allows each set to perform its specific function independently, resolving the contradiction between deflection control and vibration isolation.
Solution Approach 2:
Different mounting locations are assigned different stiffness characteristics tailored to their specific functions. The first set of links positioned to constrain engine deflection uses high stiffness, while the second set of links positioned for torque isolation uses low stiffness. This local differentiation of mechanical properties enables simultaneous achievement of both deflection control and vibration reduction.
2Object-generated harmful factors
If low mount stiffness is used to limit torque and vibration, then torque isolation is improved, but engine deflection under high gravity loads increases
Solution Approach 1:
The mounting system separates the functions of torque isolation and deflection control into two distinct sets of links. The second set with low stiffness handles torque and vibration isolation, while the first set with high stiffness maintains engine position and limits deflection. This functional segmentation eliminates the need to compromise between these conflicting requirements.
Solution Approach 2:
The patent combines two previously separate mounting functions into a single integrated system. The first set of links merges the function of positional stability, while the second set merges the function of vibration isolation. Together, they form a complete mounting solution that achieves both objectives simultaneously rather than requiring separate systems.
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 arrangement effectively isolates alternating torque forces while maintaining low deflection under high g-loading conditions, ensuring low vibratory force transmission and redundancy in the mounting system.
Implementation Method 1
The mounting stiffness being the stiffness of elastomeric bushings provided at the ends of the respective links and/or mounts
Implementation Method 2
the first set of one-degree-of-freedom links positioned relative to the rotary engine to have respective reaction axes passing through the roll axis
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A mounting arrangement for mounting a rotary engine (2) to an aircraft structure, wherein the engine has a three orthogonal axes comprising: a roll axis (5); a pitch axis (14); and a yaw axis (15). The mounting arrangement comprises: one-degree-of-freedom links with reaction axes passing through the roll axis (5). A separate roll constraint has a moment reaction about the roll axis (5) to decouple the torque roll mode from the other one-degree-of-freedom links.