Rotor Vibration Attenuator With Repositionable Counterweights
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Solution Overview
Problem
Rotary-wing aircraft face challenges in accurately predicting and mitigating vibrations caused by rotor configurations, which can reduce component lifespan and cause passenger discomfort, as existing vibration attenuation systems are inadequate in effectively managing these vibrations.
Innovation Solution
The development of mast- or hub-mounted vibration attenuators that utilize rotating weight systems with passive or active positioning capabilities to create opposing whirling shear forces, allowing for configuration adjustments between minimum- and maximum-force settings to counteract rotor-induced vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vibration attenuation systems are used, then some vibration reduction is achieved, but the systems are inadequate in effectively managing rotor-induced vibrations
Solution Approach 1:
The patent employs a dynamic vibration attenuator system where counterweights can be actively repositioned during operation to adapt to changing vibration modes. The system transitions from static to dynamic configuration, allowing the attenuator to respond to unpredictable vibration patterns generated by rotor operations such as blade flapping and gust loads.
Solution Approach 2:
The system changes physical parameters including the position, mass distribution, and rotational speed of counterweights to optimize vibration cancellation. By varying these parameters in real-time, the attenuator can effectively counteract different vibration frequencies and amplitudes that occur during various flight conditions.
2Power
If rotor blades operate at high rotational speeds, then lift and propulsion forces are generated, but vibrations are transmitted through the rotor mast into the airframe
Solution Approach 1:
The patent utilizes counterweights positioned on the rotor hub that generate opposing forces to cancel out vibrations from the rotor blades. These counterweights are strategically placed and sized to create balancing moments that counteract the vibratory forces transmitted through the rotor mast, thereby protecting the airframe from harmful vibrations while maintaining high rotational speeds for power generation.
Solution Approach 2:
The vibration attenuation system employs asymmetric mass distribution through strategically positioned counterweights that are not uniformly distributed around the rotor hub. This asymmetric configuration allows the system to target specific vibration modes and frequencies, creating optimal cancellation effects for the dominant vibration harmonics generated by the rotor blades.
3Object-affected harmful factors
If vibration attenuation systems are added to reduce vibrations, then passenger comfort and component life are improved, but device complexity increases
Solution Approach 1:
The patent integrates the vibration attenuation system with the existing rotor hub structure, merging the counterweight mechanism into the primary rotor assembly rather than adding separate attenuators. This consolidation reduces overall system complexity by utilizing shared structural components and drive mechanisms, while still achieving effective vibration reduction for improved passenger comfort and component longevity.
Solution Approach 2:
The vibration attenuation system is designed to be self-regulating, where the counterweights automatically position themselves to counteract vibrations without requiring complex external control systems. The system uses the rotor's own rotational energy and the natural dynamics of the counterweight mechanism to achieve vibration cancellation, minimizing the need for additional sensors, actuators, and 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
These attenuators effectively reduce vibrations by balancing shear forces, extending component life and improving passenger comfort through precise control of rotational velocities and configurations, thereby addressing the unpredictability of rotor vibrations.
Implementation Method 1
The attenuator rotates relative to the rotor and has at least two masses, which are passively or actively positionable to configurations between and including a minimum-force configuration, which produces a small shear force or no shear force, and a maximum-force configuration
Data Source
AI summary
A vibration attenuator for a rotor of an aircraft has a track housing adapted for rotation relative to the rotor and configured for rotation at a second angular velocity greater than a first angular velocity of the rotor. A track is located within the track housing and has a reaction surface, a pair of weights being configured for movement within the track and in contact with the reaction surface. A stop assembly has a pair of stops spaced 180 degrees apart, the stops separating the weights from each other, and each weight being allowed to travel within the track between the stops. A motor rotates the track housing relative to the rotor. The weights are free to travel relative to each other between a minimum-force configuration, in which the weights are positioned 180 degrees apart, and a maximum-force configuration, in which both weights are adjacent one of the stops.