Coaxial Rotorcraft Damper with Segmented Return Means
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional rotorcraft dampers either require bulky designs for effective damping or compromise on safety due to the limitations of single or dual damper arrangements, leading to issues with ground resonance and kinematic chain resonance.
Innovation Solution
A damper design featuring internal and external end reinforcements with coaxial return members, providing adjustable stiffness and damping characteristics, allowing for secure implementation and effective damping between blades and the hub, while also addressing kinematic chain resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single or dual damper arrangements are used, then the device complexity is reduced, but the reliability and safety are compromised due to inability to effectively prevent ground resonance and kinematic chain resonance
Solution Approach 1:
The damper is segmented into multiple independent return means (first return means and second return means) with different stiffness characteristics. Each return means connects adjacent armatures through distinct paths, allowing independent operation and failure isolation. This segmentation enables the system to maintain reliability even if one return means fails, while avoiding the complexity of fully redundant systems.
Solution Approach 2:
The damper structure serves multiple functions simultaneously: it provides ground resonance damping through the first return means, kinematic chain resonance damping through the second return means, and structural support through the armature framework. This multi-functionality allows a single device to address multiple resonance issues without requiring separate dedicated dampers for each function.
2Speed
If the stiffness of the damper is increased to move the natural frequency away from resonance zones, then the frequency adaptation is improved, but the damping capability is reduced
Solution Approach 1:
Different return means are assigned different local stiffness qualities - the first return means has higher stiffness for frequency adaptation while the second return means has lower stiffness for optimal damping. This local differentiation allows each return means to be optimized for its specific function rather than requiring uniform properties throughout the entire damper structure.
Solution Approach 2:
The system changes the stiffness parameter across different return means rather than using a single stiffness value. By varying the stiffness parameter (k1 for first return means, k2 for second return means), the damper can simultaneously achieve the frequency shift needed to avoid ground resonance and the damping needed to suppress kinematic chain resonance.
3Productivity
If the lever arm between the damper and drag axis is increased to reduce the number of blades, then the productivity is improved, but the device complexity and size are increased
Solution Approach 1:
The damper structure nests multiple armatures and return means within a compact radial arrangement. The intermediate armature is positioned between the inner and outer armatures, creating a nested configuration that maximizes the lever arm effect without proportionally increasing the overall device size. This nested arrangement allows the damper to effectively support more blades without requiring a proportional increase in device complexity.
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 damper effectively increases the natural frequency of blade drag modes, moving them away from resonance zones, providing enhanced stability and safety by simultaneously offering both stiffness and damping, thus preventing ground and kinematic chain resonance.
Implementation Method 1
These dampers comprise elastic return means with determined stiffness and damping, to oppose resonance phenomena
Implementation Method 2
the return member comprises an intermediate armature coaxial with the inner end armature and with the outer end armature, the return member having a first return means and a second return means
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The present invention relates to a shock absorber (10) having a coaxial inner end armature (20) and outer end armature (30), a return member (40) being arranged between the inner end armature (20) and the outer end armature (30). The return member (40) comprises an intermediate armature (43) coaxial with the inner end armature (20) and the outer end armature (30), said return member (40) having a first return means (41) and a second return means (42), said first return means (41) being arranged between the outer end armature (30) and said intermediate armature (43), said second return means (42) being arranged between the inner end armature (20) and said intermediate armature (43).