Rotorcraft Blade Flap Abutment with Centrifugal Release
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Solution Overview
Problem
Existing rotorcraft stop mechanisms for limiting blade flapping are inefficient, particularly during startup and stationary phases, leading to mechanical stress and potential damage from external forces like high winds, and require complex structures for rapid deployment and storage.
Innovation Solution
A bistable latch mechanism with magnetic engagement and release locks, utilizing centrifugal force and elastic deformation to control the movement of upper abutment members between engagement and release positions, allowing for rapid transition and minimizing mechanical stress, while maintaining effective flapping control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stop mechanism is used to limit blade flapping during stationary phase, then blade protection from external forces is improved, but mechanical stress and potential damage occur during startup phase
Solution Approach 1:
The stop mechanism is designed to be dynamic rather than static. The upper stop members can move between an engaged position (limiting flapping) and a retracted position (allowing blade movement). During startup, centrifugal force automatically causes the stop members to retract, eliminating mechanical stress on the blades while still providing protection during stationary phase when centrifugal force is insufficient to retract them.
2Speed
If a complex structure is used for rapid deployment and storage of stop mechanism, then transition speed is improved, but device complexity increases
Solution Approach 1:
The stop mechanism is designed to operate automatically based on the rotational state of the rotor. Centrifugal force generated during rotor rotation automatically causes the stop members to retract from the engaged to retracted position. During stationary phase, the stop members automatically return to the engaged position. This self-actuating mechanism eliminates the need for complex control systems, motors, or actuators while achieving rapid transition between states.
3Reliability
If upper stop members are engaged to limit flapping mobility, then blade protection is improved, but blade mobility for pitch variation is restricted
Solution Approach 1:
The stop mechanism transitions from a static to a dynamic configuration based on rotor operational state. During stationary phase, the upper stop members are engaged to limit flapping mobility and protect the blades. During rotation, centrifugal force causes the stop members to retract, fully restoring blade mobility for pitch variation maneuvers. This dynamic reconfiguration resolves the contradiction between protection and adaptability.
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 enables rapid and reliable transition of upper stop members between engagement and release positions, reducing mechanical stress and enhancing operational efficiency without increasing structural complexity, thus improving the durability and performance of the rotorcraft's stop mechanism.
Implementation Method 1
One of the maneuvering means is by centrifugal force and induces a retraction of the abutment members
Implementation Method 2
the other maneuvering means is by spontaneous return of the abutment members to the initial position of limitation in flapping mobility of the blades
Data Source
Figure 1~3
Figure 4~5(b)
Figure 6~8
AI summary
The invention relates to a stop mechanism for limiting the flapping of the blades of a rotor (1). Upper stop members (6) are actuated towards an engagement position by means of return levers (13) exerting an intrinsic return force (R), and towards a release position by a counterweight (10) exerting a centrifugal force (C) under the effect of the rotation of the rotor (1). At least one bistable magnetic lock (15) is selectively engaged with the upper stop members (6). When the rotor (1) is stopped and during the starting phase, an engagement lock (15) is engaged with the upper stop member (6) against its movement from the engagement position to the release position. At a predetermined centrifugal force threshold, the engagement lock (15) is released from the upper stop member (6), and the movement of the upper stop member (6) into the release position is rapid.