Coaxial Spinner Vibration Attenuator for Low-Mass Rotor Control
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Solution Overview
Problem
Rotary-wing aircraft experience vibrations due to rotor configurations, which are difficult to predict and can reduce component life and passenger comfort, with existing vibration attenuation systems adding significant mass or affecting structural integrity.
Innovation Solution
A vibration attenuation device with coaxial, dual-plane spool-shaped spinners having balanced eccentric weights, which create an out-of-plane moment without shear force, allowing for active control using two motors to manage the moment, and can operate in passive, semi-active, or fully active modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional vibration attenuation systems are used, then vibration reduction is achieved, but significant mass is added to the aircraft
Solution Approach 1:
The vibration attenuation system is divided into multiple independent spinner assemblies (first and second spinners) that can be distributed around the rotor mast. Each spinner contains its own eccentric weights and can operate independently or in coordination, allowing the vibration cancellation function to be segmented across multiple lightweight components rather than requiring a single large mass.
Solution Approach 2:
The system uses eccentric weights on the spinners to generate counteracting centrifugal forces that oppose the harmful vibrations. By rotating these eccentric masses at controlled speeds and positions, the system creates anti-vibration forces that cancel out the rotor-induced vibrations without requiring significant additional structural mass.
2Object-affected harmful factors
If conventional vibration attenuation systems are used, then vibration reduction is achieved, but structural integrity is affected
Solution Approach 1:
The vibration attenuation function is localized to specific spinner assemblies that can be mounted on the rotor mast without requiring modifications to the main airframe structure. Each spinner is a self-contained unit that attaches locally to the mast, concentrating the structural impact to small, designed mounting points rather than distributing stress across critical structural members.
Solution Approach 2:
The spinners act as intermediary components between the rotor mast and the vibration cancellation function. They provide a mechanical interface that isolates the mast from direct structural modifications, allowing vibration attenuation to be achieved through the spinners' rotating masses without compromising the integrity of the main rotor support structure.
3Device complexity
If passive vibration attenuation is used, then simplicity is maintained, but adaptability to different frequencies is limited
Solution Approach 1:
The spinner assemblies are designed with the capability to transition from passive rotation to actively controlled rotation. The eccentric weights can be rotated at variable speeds and positions through motor control, allowing the system to adapt its vibration cancellation characteristics to match different rotor operating frequencies and vibration modes dynamically rather than being fixed for a single frequency.
Solution Approach 2:
The system allows changes in operational parameters such as spinner rotation speed, eccentric weight position, and phase angle between multiple spinners. These parameter adjustments enable the vibration attenuation system to effectively operate across a range of frequencies and vibration conditions, providing versatility without requiring complex control electronics.
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
The solution effectively reduces vibrations with less mass than prior systems, providing active control to optimize vibration reduction across various frequencies and configurations, enhancing aircraft component life and passenger comfort.
Implementation Method 1
coaxial, dual-plane spool-shaped spinners having balanced eccentric weights, which create an out-of-plane moment without shear force
Implementation Method 2
A vibration attenuation device with coaxial, dual-plane spool-shaped spinners having balanced eccentric weights, which create an out-of-plane moment without shear force, allowing for active control using two motors to manage the moment
Data Source
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AI summary
A vibration attenuator (117) for an aircraft (101) has first and second coaxial spinners (121, 133) configured for rotation about a mast axis (115) and relative to a rotor (109). Upper and lower weights of each spinner (121, 133) are spaced radially from the axis (115) and positioned 180 degrees from each other about the axis (115). The weights of each spinner (121, 133) are spaced from each other a distance parallel to the mast axis (115), each weight rotating about the mast axis (115) in a different plane. The spinners (121, 133) rotate together relative to the rotor (109) at a selected angular rate and are selectively rotatable relative to each other between a minimum-moment configuration, in which the upper weight of each spinner (121, 133) is angularly aligned with the lower weight of the other spinner (121, 133), and a maximum-moment configuration, in which the upper weights are angularly aligned and the lower weights are angularly aligned, producing a whirling moment about the mast axis (115) as the spinners rotate(121, 133).