Variable Rotary Pendulous Mass Vibration Suppression
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Solution Overview
Problem
Conventional vibration suppression systems in rotary-wing aircraft, such as helicopters, are inadequate in effectively reducing vibrations at the source, leading to structural fatigue and transmission of vibrations to other systems, as they often rely on active counter-vibration devices that are not optimally positioned to counteract high levels of vibration.
Innovation Solution
A variable rotary mass vibration suppression system is introduced, comprising a vibration control mass with a center of mass and two rotors with offset coupling centers, allowing for a controllable vibration control force vector magnitude and frequency. This system includes motors and a controller to adjust the displacement angle and speed differential between the rotors, optimizing the vibration suppression by varying the radial and axial coupling distances and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active counter-vibration devices are used, then vibrations can be suppressed at remote locations, but the vibration suppression effectiveness at the source is inadequate
Solution Approach 1:
The patent transitions from remote vibration suppression to source-level suppression by mounting the counter-vibration mass directly on the rotor hub, changing the spatial dimension of intervention from downstream (fuselage) to upstream (rotor source). This dimensional shift in positioning achieves superior vibration suppression effectiveness at the source.
Solution Approach 2:
The hub-mounted system performs preliminary vibration counteraction at the origin of vibration generation, before vibrations propagate to the fuselage and other systems. By positioning the counter-vibration mass on the rotor hub, the system preemptively neutralizes vibrational forces at their source.
2Adaptability or versatility
If fixed coupling distances are used, then the system structure is simplified, but the adaptability to different vibration conditions is reduced
Solution Approach 1:
The patent employs variable coupling distances between the counter-vibration mass and rotor hub, allowing the system to dynamically adjust its configuration. This dynamic adaptability enables optimization of vibration suppression performance across different operating conditions and vibration frequencies.
Solution Approach 2:
The system allows modification of coupling parameters (radial and axial distances) to change the operational characteristics of the counter-vibration mechanism. By varying these parameters, the system adapts to different vibration magnitudes, frequencies, and directional components.
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 system effectively suppresses vibrations by varying the displacement angle and speed differential, achieving a controllable vibration control force vector that can range from minimal to maximum, thereby reducing structural fatigue and vibration transmission.
Implementation Method 1
a first rotor (28, 128, 302) having a first axis of rotation coincident with the central axis; a second rotor (30, 130, 402) having a second axis of rotation coincident with the central axis... wherein the first rotor and the second rotor are controllable to produce a vibration control force vector (41, 41A) having a controllable magnitude and frequency about the central axis
Data Source
AI summary
A vibration suppression unit for an aircraft comprising a mass having a center of mass, a first rotor, a second rotor, a first coupling between the first rotor and the mass, a second coupling between the second rotor and the mass, the first and second couplings having first and second coupling centers offset perpendicularly from a central axis of rotation by different radial distances and offset in axially from the center of mass with respect to the central axis by different axial distances, the first and second coupling centers having a selectively variable displacement angle defined by the angle between lines extending between the central axis of rotation and the first coupling center and the second coupling center, respectively, wherein the first rotor and the second rotor are controllable to produce a vibration control force vector having a controllable magnitude and frequency about the central axis.