Hover Rotor Vibration Attenuator With Phase-Controlled Mass Units
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Solution Overview
Problem
Current rotor systems for hover-capable aircraft, such as helicopters, face challenges in effectively attenuating vibrations transmitted from the mast to the fuselage, leading to discomfort for occupants due to high-frequency vibrations, and existing active attenuating devices are bulky and require complex components, limiting their flexibility and responsiveness.
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 a compact transmission unit with epicyclic trains to efficiently transfer motion, along with control units using belt transmissions to adjust the angle between masses for optimal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive attenuating devices are used, then simplicity of construction is improved, but vibration attenuation performance deteriorates
Solution Approach 1:
The patent employs dynamic vibration absorbers (masses) that rotate at specific speeds to generate centrifugal forces counteracting vibrations. The system transitions from static passive masses to dynamically controlled active masses whose rotational speed and position can be adjusted to optimize attenuation across different operating conditions, thereby improving performance while maintaining reasonable construction simplicity.
Solution Approach 2:
The invention changes parameters by controlling the rotational speed of masses and their angular positions to generate attenuating forces at specific frequencies. By adjusting these parameters, the system can target different vibration frequencies (including N*Ω and its multiples), significantly improving attenuation performance compared to fixed passive devices.
2Reliability
If active attenuating devices are used, then vibration attenuation performance is improved, but device complexity and size worsen
Solution Approach 1:
The patent merges multiple functions into a single integrated system: the masses serve both as vibration absorbers and as elements whose rotational dynamics generate attenuating forces. The control system combines speed control and position control into a unified active attenuation mechanism, reducing overall system complexity while maintaining high performance.
Solution Approach 2:
The invention utilizes mechanical vibration principles by employing rotating masses that generate centrifugal forces to counteract vibrations. This mechanical approach avoids complex electronic or hydraulic systems, achieving high attenuation performance through well-understood mechanical principles while keeping the device relatively simple.
3Reliability
If active attenuating devices are used, then vibration attenuation performance is improved, but responsiveness to changing vibrations worsens
Solution Approach 1:
The system achieves high responsiveness through dynamic control of mass rotation. The active control mechanism can rapidly adjust the rotational speed and angular position of masses to match changing vibration conditions, enabling the system to respond quickly to varying vibration magnitudes and frequencies while maintaining optimal attenuation performance.
Solution Approach 2:
The invention incorporates feedback control where sensors detect vibrations and the control system adjusts mass rotation accordingly. This closed-loop feedback mechanism enables rapid response to changing vibration conditions, with the system continuously adapting mass positions and speeds to counteract new vibration patterns as they occur.
4Reliability
If complex parts are used, then vibration attenuation performance is improved, but weight and cost worsen
Solution Approach 1:
The patent employs a self-service approach where the rotating masses generate their own centrifugal forces for vibration attenuation without requiring external power sources or complex actuation systems. The system uses the rotational motion itself to create the attenuating forces, eliminating the need for additional heavy components and reducing overall system weight while maintaining high performance.
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 provides precise and rapid attenuation of vibrations, reducing the need for complex parts, weight, and cost, while enhancing flexibility and responsiveness to changing vibration magnitudes and directions, thereby improving occupant comfort and operational efficiency.
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
AI summary
A rotor for an aircraft is described that has a mast, an attenuating device to attenuate the transmission of vibrations from the mast in a plane orthogonal to the first axis; and a transmission device interposed between the mast and the attenuating device; the attenuating device comprises a first and a second mass unit with a first and a second mass rotatable about the first axis with a first and a second rotational speed, two control units operable to cause an additional rotation of at least one of the first and second masses; and a first and a second support assembly carrying the first and second masses; each control unit controls the angle between the first and second masses and each control unit comprises: a belt coupled to the support assembly and a drive unit coupled to the first belt, to cause the rotation of the first support assembly with respect to said transmission device.