Rotorcraft Flapping Abutment Mechanism Design
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Solution Overview
Problem
Existing rotorcraft rotor systems face challenges in effectively limiting the flapping movement of blades, particularly during startup and in windy conditions, with current stop mechanisms being complex, heavy, and requiring multiple mechanical parts, which can lead to unbalance and inefficiency.
Innovation Solution
A rotorcraft rotor with a single cylindrical abutment per lift assembly, hinged to the hub, that moves between an engagement and disengagement position based on rotation speed, using a flyweight and return spring to control flapping, allowing for efficient blocking and release of blade movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stop mechanisms with multiple mechanical parts are used, then flapping movement can be limited, but device complexity and mass increase
Solution Approach 1:
The patent combines multiple stop mechanisms into a single integrated abutment structure. The abutment includes both upper and lower stop surfaces that limit flapping in both directions, replacing what would traditionally require separate upper and lower stop members. This merging reduces the number of mechanical parts while maintaining the ability to limit flapping movement effectively.
Solution Approach 2:
The single abutment structure serves multiple functions: it limits upward flapping via its upper stop surface, limits downward flapping via its lower stop surface, and provides a unified mounting interface to the hub. This multi-functionality eliminates the need for separate stop mechanisms for different flapping directions, reducing overall device complexity.
2Reliability
If traditional stop mechanisms with multiple mechanical parts are used, then flapping movement can be limited, but mass increases
Solution Approach 1:
The patent combines multiple stop mechanisms into a single integrated abutment structure. The abutment includes both upper and lower stop surfaces that limit flapping in both directions, replacing what would traditionally require separate upper and lower stop members. This merging reduces the number of mechanical parts while maintaining the ability to limit flapping movement effectively.
3Ease of manufacture
If fixed abutment tracks are used, then manufacturing is simplified, but flapping control flexibility is reduced
Solution Approach 1:
The patent introduces a movable abutment that can shift position along the abutment track in response to centrifugal forces during rotor operation. The abutment is not fixed in position but can dynamically adjust its location to engage with different portions of the track, allowing the system to maintain simple fixed track manufacturing while achieving flexible flapping control through the movable abutment's dynamic positioning.
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 solution simplifies the stop mechanism, reduces mass and complexity, and allows for efficient flapping control in both directions, enhancing rotor performance and reducing mechanical parts, while maintaining stability and balance.
Implementation Method 1
When the rotor is rotating, the centrifugal forces exerted induce the rotation of the flyweight around the axis of displacement. The stop consequently performs a rotation around this axis of movement together with the flyweight.
Implementation Method 2
a return spring exerting a force on the mechanism to tend to position said stop in the position of 'commitment.' When the rotor is not driven in rotation, the stop is in the engagement position.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A rotor carrying a plurality of lift assemblies, each having a retention and mobility member. An abutment mechanism of a lift assembly includes an abutment track arranged on the retention and mobility member and a single cylindrical abutment that is movable in pivoting about a movement axis, said abutment extending over a height in elevation and also over a length and over a width. The length is greater than said width, and said height is greater than said length. A fly-weight is secured to pivot with said abutment, and a return spring exerts a force on said fly-weight.