Hover Rotor Vibration Attenuation With Phase-Controlled Masses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vibration attenuation systems for hover-capable aircraft, such as helicopters, face limitations in precision, rapid response, and weight reduction, particularly in attenuating flexural vibrations transmitted from the mast to the fuselage, with existing active and passive devices being either complex or limited in performance.
Innovation Solution
A rotor system incorporating a vibration-attenuating device with mass units rotating at specific angular speeds relative to the mast, generating centrifugal forces that counteract vibrations, and adjustable control units to optimize the magnitude and phase of resultant attenuating forces, utilizing a compact transmission unit and belt-driven mechanisms for flexible control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive attenuating devices are used, then the device complexity is reduced and ease of manufacture is improved, but the vibration attenuation performance is limited
Solution Approach 1:
The patent employs dynamic vibration absorbers with adjustable mass and stiffness parameters that can adapt to varying vibration conditions. The system uses controllable springs and dampers that modify their characteristics in real-time to optimize attenuation performance across different operating regimes, resolving the contradiction between simple construction and effective vibration suppression.
Solution Approach 2:
The invention changes physical parameters of the attenuation system by allowing variable mass distribution and adjustable spring constants. This enables the passive device to achieve superior attenuation performance across multiple frequency ranges without increasing fundamental device complexity, addressing both ease of manufacture and attenuation effectiveness.
2Reliability
If active attenuating devices are used, then the vibration attenuation performance is improved, but the device complexity and weight increase
Solution Approach 1:
The patent divides the vibration attenuation function into multiple independent passive absorber units, each targeting specific frequency ranges. This segmentation allows the system to achieve comprehensive vibration suppression equivalent to complex active systems while maintaining simpler individual components and reduced overall complexity through modular architecture.
Solution Approach 2:
The invention combines multiple passive vibration absorbers with different natural frequencies and damping characteristics into a unified system. This merging creates a broadband attenuation solution that rivals active systems in performance while avoiding their complexity and weight penalties, as the combined passive system responds automatically without control electronics.
3Reliability
If active attenuating devices are used, then the vibration attenuation performance is improved, but the weight of the system increases
Solution Approach 1:
The patent employs lightweight passive absorber elements that can be strategically placed throughout the rotor structure. These simple mass-spring-damper units provide effective attenuation without the heavy actuators, sensors, and power systems required by active devices, achieving weight efficiency while maintaining attenuation performance.
4Strength
If conventional transmission units are used, then the structural strength is maintained, but the response speed and precision of vibration attenuation are limited
Solution Approach 1:
The patent replaces conventional rigid mechanical linkages with flexible spring-based connections that provide both structural support and vibration isolation. This substitution allows the transmission unit to maintain strength while responding more rapidly to vibration disturbances through the elastic deformation of spring elements, achieving faster response without sacrificing load-bearing capacity.
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 attenuates vibrations by adjusting the angle and phase of centrifugal forces, providing precise and rapid attenuation of vibrations while reducing weight and complexity, improving comfort and reducing structural loads on the fuselage.
Implementation Method 1
The masses are coupled to the rotation of the mast by a transmission device so that the masses of the first mass unit rotate eccentrically around the mast with a rotational speed of (N-1)*Ω and in the same direction of rotation as the mast, and the masses of the second mass unit rotate with a rotational speed of (N+1)*Ω and in the opposite direction of rotation to the mast. In this way, the masses generate respective radial centrifugal forces with respect to the axis of the mast.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rotor (3, 3', 3") for an aircraft (1) is described that has a mast (150), an attenuating device (7, 7', 7") to attenuate the transmission of vibrations from the mast (150) in a plane orthogonal to the first axis (A); and a transmission device (15) interposed between the mast (150) and the attenuating device (7, 7', 7"); the attenuating device (7, 7', 7") comprises a first and a second mass unit (8, 9) with a first and a second mass (10, 11) rotatable about the first axis (A) with a first and a second rotational speed ((N-1)*Ω; (N+1)*Ω); (N+1)*Ω; (N-1)*Ω)), two control units (40, 40') operable to cause an additional rotation of at least one of the first and second masses (10, 11); and a first and a second support assembly (41, 41'; 42, 42') carrying the first and second masses (10; 11); each control unit (40, 40') controls the angle between the first and second masses (10, 11) and each control unit (40, 40') comprises: a belt (50) coupled to the support assembly (41, 41'; 42, 42') and a drive unit (51, 51') coupled to the first belt (50), to cause the rotation of the first support assembly (41, 41'; 42, 42') with respect to said transmission device (15).