Toroidal Elastomer Support for Helicopter Rotor Vibration Damping
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Solution Overview
Problem
Existing vibration damping systems for helicopters are complex, heavy, and difficult to install, particularly on ultralight aircraft, and fail to effectively differentiate elastic properties along orthogonal directions, limiting the degree of freedom of the rotor shaft while maintaining control angles.
Innovation Solution
A shock-absorbing support system using a lattice structure with toroidal elastic members made of elastomeric materials, such as NBR, HNBR, or XNBR, connected via flexible connectors and screw means to the rotor transmission and frame, allowing for increased freedom of movement by damping longitudinal, transverse, and torsional stresses through adjustable elastic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic vibration-damping devices with hinges and elastic members are used to damp vibrations, then vibration damping performance is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential vibration damping function from complex hydraulic devices and implements it through a simplified elastic member system. The elastic member (14) directly connects the rotor hub to the frame, eliminating the need for hydraulic mechanisms, hinges, and multiple elastic members, while maintaining effective vibration damping in longitudinal, transverse, and torsional directions.
Solution Approach 2:
The single elastic member (14) performs multiple vibration damping functions simultaneously - it dampens vibrations in the longitudinal direction, transverse direction, and torsional direction, replacing the need for separate hydraulic devices and multiple elastic members required by conventional systems.
2Manufacturing precision
If skilled labor is used to perform preliminary positioning and centering operations, then installation precision is improved, but installation time increases
Solution Approach 1:
The elastic member (14) is pre-formed with specific geometric characteristics (toroidal shape with defined curvature radii) that inherently provide the correct positioning and centering properties. This preliminary design eliminates the need for skilled workers to perform delicate preliminary operations during installation, as the component self-aligns and positions itself correctly.
3Reliability
If heavy vibration-damping devices are installed, then vibration damping capability is improved, but weight increases
Solution Approach 1:
The patent employs a simple elastic member (14) made of elastomeric material that can be replaced easily if needed, rather than using heavy, complex hydraulic vibration-damping devices. This approach reduces weight while maintaining effective vibration damping capability through the elastic properties of the material.
4Adaptability or versatility
If elastic properties are made adjustable to accommodate varying stress directions, then adaptability is improved, but device complexity increases
Solution Approach 1:
The elastic member (14) has non-uniform local properties - different curvature radii in different directions (first curvature radius in longitudinal direction, second curvature radius in transverse direction). This local variation in geometric quality provides different elastic characteristics for different stress directions, enabling adaptability without requiring adjustable mechanisms or complex control systems.
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 reduces rotor-induced vibrations, enhancing flight comfort and maintaining aircraft control while being cost-effective and easier to install, with adjustable elastic properties to accommodate varying stress directions.
Implementation Method 1
a substantially toroidal elastic member (14) made of an elastomeric material having a predetermined elastic constant
Implementation Method 2
shock-absorbing support for damping vibrations between the rotor of a helicopter and its frame
Data Source
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AI summary
A shock-absorbing support (1) for damping vibrations between a rotor (R) of a helicopter (H) and its frame (F), wherein the rotor (R) comprises a rotor mast (M) connected to an engine via a transmission (G). The support (1) comprises an outer annular body (12) defining a central axis (L) and adapted to be secured to the frame (F), an inner bush (13) coaxial with the outer annular body (12) and adapted to be secured to the transmission (G) of the rotor (R), a substantially toroidal elastic member (14) interposed between the outer annular body (12) and the inner bush (13). The elastic member (14) is made of an elastomeric material having a predetermined elastic constant and has two pairs of through slots (19, 19'; 20, 20') substantially parallel to said central axis (L), which are diametrically opposite and symmetrical with respect to two first diametrical planes (π, π') which intersect at the center axis (L) and are orthogonal to each other. The slots (19, 19'; 20, 20') have an identical substantially V-shaped cross-section with vertices (21, 21'; 22, 22') directed toward said central axis (L) and passing through the diametrical planes (π, π'). The slots (19, 19'; 20, 20') are in symmetrical positions with respect to second diametrical planes (ρ, ρ') which are at about 45° from the first diametrical planes (π, π') to thereby delimit substantially radial regions (P) entirely filled with elastomeric material.