Vibration Control System With Frictional Power Transfer
Solution Overview
Problem
Rotary wing aircraft experience significant vibrations due to oscillatory aerodynamic loading, which existing vibration cancellation systems struggle to fully address, often leading to fatigue failures and requiring large, complex setups to achieve full vibration control.
Innovation Solution
A vibration control system comprising four mass discs located at a central axis, with a power transfer assembly that includes a power transfer shaft and disc, allowing for rotational energy transfer and adjustable contact points to alter vibratory force output, enabling efficient counteraction of aircraft vibrations with fewer components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid gearbox mounting strut is replaced with a compliant strut and parallel hydraulic actuator to intercept vibration, then vibration control is improved, but fatigue failures in engine drive shafts occur due to load path interruption
Solution Approach 1:
The patent introduces an intermediary vibration control system that includes a compliant mounting strut with a hydraulic actuator and counter-rotating eccentric masses. This intermediary system intercepts vibrations from the gearbox before they reach the airframe, while the power transfer assembly with frictional contact discs transfers rotational energy without creating rigid load paths, thus preventing fatigue failures in drive shafts.
2Reliability
If six force generators with counter-rotating eccentric masses are used to counteract all six moments and forces, then full vibration control capability is achieved, but device complexity and size increase
Solution Approach 1:
The patent merges multiple vibration control functions into a single integrated system. Four mass discs mounted on a common power transfer shaft work together as one unit, where the power transfer assembly with frictional contact discs couples the discs. This unified approach provides full six-degree-of-freedom vibration control capability while requiring fewer components than six separate force generators.
Solution Approach 2:
The vibration control system with four mass discs and power transfer assembly serves multiple functions simultaneously: it counteracts rolling, pitching, and yawing moments, as well as vibratory forces in multiple directions. The frictional contact power transfer mechanism enables flexible energy distribution among the mass discs, allowing the single system to provide comprehensive vibration control that would otherwise require six separate force generators.
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 aircraft vibrations by generating adjustable forces and moments, improving occupant comfort and component reliability while minimizing the risk of fatigue failures and reducing the number of required force generators from six to three.
Implementation Method 1
a power transfer disc connected to the power transfer shaft and in frictional contact with each of the adjacent mass discs at a contact point
Data Source
AI summary
A vibration control system includes four mass discs located at a central axis and rotatable thereabout. Each mass disc includes a mass secured thereto wherein rotation of the four mass discs creates a vibratory force output. A power transfer assembly is located between adjacent mass discs of the four mass discs and is configured to transfer rotational energy between the adjacent mass discs. The power transfer assembly includes a power transfer shaft rotatable about a power transfer shaft axis and a power transfer disc connected to the power transfer shaft and in frictional contact with each of the adjacent mass discs at a contact point. When the power transfer shaft is rotated, a radial location of the contact point at each of the adjacent mass discs relative to the central axis is changed, altering the vibratory force.