Aircraft Engine Mount Layout With Fluid Damping and Motion Stops
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Solution Overview
Problem
Conventional compliant engine mount systems for aircraft face challenges in reducing vibration and force transmission while minimizing the drawbacks of elastomeric materials, such as compression set and creep, which require additional accommodation for motion control and incorporation of snubbing elements to manage undesired motions over time.
Innovation Solution
The proposed engine mount system incorporates a top mount, lower mount, and center trunnion mount with mechanical, elastomeric, and fluidic damping components, featuring a flexing element, fluid-filled cavities, and interlocking linkages with compression and tension stops to isolate vibrations and allow transmission of abnormal forces, utilizing a gas-filled bladder to tune inertial effects and accommodate thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If elastomeric materials are used in compliant engine mount systems, then the ability to compensate and control larger ranges of motion with softer spring rates is improved, but the materials tend to take compression set and exhibit creep characteristics over time, requiring additional motion accommodation
Solution Approach 1:
The engine mount system is divided into multiple functional components: rigid structural elements (mounting brackets, links) and compliant elements (elastomeric materials, fluid chambers). This segmentation allows each component to perform its specific function - the rigid parts provide structural support and motion control, while the compliant parts provide vibration isolation and force reduction, resolving the contradiction between motion adaptability and dimensional stability
Solution Approach 2:
The system combines elastomeric materials with rigid metallic components and fluid-filled chambers to create a composite mounting system. The elastomeric materials provide the necessary compliance and motion compensation, while the rigid components maintain structural integrity and prevent excessive deformation, thereby achieving both motion control capability and dimensional stability over time
2Stability of the object's composition
If stops (snubbing elements) are incorporated in conjunction with elastomers, then excess undesired motions are minimized, but the stops must be set to accommodate the set and creep of elastomeric materials during the life of the mounting system, requiring additional motion control capability
Solution Approach 1:
The stops are pre-positioned during manufacturing to account for expected elastomeric compression set and creep over the component's service life. This preliminary adjustment ensures that the stops provide appropriate motion limiting throughout the entire operational period without requiring additional adjustment mechanisms or increasing system complexity
Solution Approach 2:
The elastomeric materials serve as intermediaries between the rigid mounting structure and the engine, absorbing dimensional changes due to compression set and creep. This allows the stops to be positioned based on initial dimensions while the elastomers compensate for changes over time, maintaining motion stability without requiring complex adjustment mechanisms
3Object-generated harmful factors
If conventional compliant mounting systems are used to reduce vibration and force transmission, then good reduction is achieved, but increased motion is induced compared to stiffer hard engine mounting systems
Solution Approach 1:
The mounting system employs dynamic characteristics through fluid-filled chambers and elastomeric materials that provide frequency-dependent response. At vibration frequencies, the compliant elements provide soft mounting characteristics for vibration isolation, while the overall system geometry and rigid components limit the range of motion, achieving both vibration reduction and motion control
Solution Approach 2:
The system changes the effective stiffness parameter based on operating conditions. The elastomeric materials and fluid chambers provide non-linear spring characteristics that offer softer compliance for vibration frequencies while maintaining stiffer overall behavior for large displacement motions, thereby reducing both vibration transmission and excessive engine motion
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 system effectively isolates the aircraft from vibrations and normal forces while enabling the transmission of abnormal forces, providing improved durability and reduced noise and vibration transmission, with enhanced mechanical stability and reduced reliance on elastomeric materials.
Implementation Method 1
a cavity having a gas-filled space/bladder therein. Upon a movement of the upper link relative to the housing, the flexing element is configured to deform and to cause a pumping of fluid into or out of the cavity to change a volume of the gas-filled space/bladder
Implementation Method 2
The flexing element is configured to deform and to cause a pumping of fluid into or out of the cavity
Implementation Method 3
the flexing element is configured to deform and to cause a pumping of fluid into or out of the cavity to change a volume of the gas-filled space/bladder
Data Source
AI summary
Compliant mounting systems, devices, and methods for mounting a vehicle engine to a vehicle structure or base include a top mount, a lower mount, a center trunnion mount, and an aft mount which are configured to react forces transmitted by the engine to the vehicle structure. Metallic and elastomeric elements can provide vibrational and force isolation characteristics. Stops (e.g., snubbing elements) allow for a specific range of motion before internal mount structures contact each other to act as a conventional hard mount. Fluid elements and compressible gas-filled spaces/bladders may be incorporated to provide fluid damping behaviors to complement the metallic and elastomeric elements.