Rotor Hub Vibration Attenuator Using Active Weights
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vibration attenuation systems for rotor hubs in rotary-wing aircraft, such as helicopters and tiltrotors, face challenges in accurately predicting and effectively reducing vibrations, particularly due to variations in dynamic characteristics and susceptibility to transients, leading to inadequate vibration reduction and potential amplification of vibrations in other areas of the airframe.
Innovation Solution
A vibration attenuator system that includes rotating pairs of unbalanced weights driven by electric motors or torque from the mast, generating centrifugal forces to cancel rotor-induced vibrations, with a microprocessor-based control system using feedback from sensors to adjust the amplitude and phase of these forces to minimize vibrations transmitted to the airframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive mast-mounted rotating balancer (UREKA device) is used to reduce vibrations, then rotor imbalance vibrations are minimized, but the device amplifies vibration when mast attachment point does not possess supercritical shaft characteristics
Solution Approach 1:
The vibration attenuator uses actively controllable unbalanced weights that can dynamically adjust their rotational speed and phase angle in response to detected vibration conditions, transforming the static passive system into a dynamic adaptive system that maintains effectiveness across varying operational conditions
Solution Approach 2:
The system incorporates vibration sensors and control systems that continuously monitor vibration levels and adjust the attenuator's operation accordingly, creating a closed-loop feedback mechanism that ensures reliable vibration attenuation without amplification
2Object-affected harmful factors
If UREKA device with heavy rollers in circular steel track is used, then oscillatory force is created to minimize vibration, but the device is susceptible to gusts and transients which disturb roller position and create vibration transient
Solution Approach 1:
Vibration sensors continuously monitor the system state and provide feedback to the control mechanism, enabling real-time correction of disturbances caused by gusts and transients, thereby maintaining stable operation
Solution Approach 2:
The actively controllable unbalanced weights can autonomously adjust their position and rotational characteristics in response to detected disturbances, enabling the system to self-correct without external intervention
3Object-affected harmful factors
If vibration attenuators are attached to rotor hub for rotation about mast axis, then rotor-induced vibrations are canceled through centrifugal forces, but the system complexity increases with active control mechanisms
Solution Approach 1:
The system replaces complex passive mechanical vibration isolation structures with actively controllable unbalanced weights that generate counteracting centrifugal forces, simplifying the overall mechanical design while maintaining effectiveness through controlled force generation
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 reduces rotor-induced vibratory forces, improving the fatigue life of structural components, reducing avionics and engine vibration, and enhancing passenger comfort by canceling the source of vibratory loads, while being lighter and more compact than existing solutions.
Implementation Method 1
rotating pairs of unbalanced weights driven by electric motors or torque from the mast, generating centrifugal forces to cancel rotor-induced vibrations
Data Source
AI summary
A vibration attenuator for an aircraft has at least one weight mounted in a rotating system of a rotor hub of the aircraft, each weight being rotatable about an axis of rotation of the hub relative to the hub and to each other weight. Drive means are provided for rotating each weight about the axis of rotation at a selected speed for creating oscillatory shear forces that oppose and attenuate rotor-induced vibrations having a selected frequency. A vertically oriented vibration attenuator is configured to oppose and attenuate vertical rotor induced oscillatory forces that would otherwise travel vertical down the rotor mast and into the airframe. A vibration attenuator having weights rotating about separate axes offset from each other.