Scissor Linkage Leading-Edge Flap Gap Optimization
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Solution Overview
Problem
Common kinematics for extending leading-edge slats, such as Krüger flaps, often result in a strict motion that does not optimize the gap between the flap and the wing, affecting airflow and flow shape during deployment.
Innovation Solution
A flap system utilizing a scissor arrangement with two scissor links and a connecting link, actuated by a rotary mechanism, allowing for a non-proportional angle change between the flap and the wing chord, enabling a translational motion that maintains a consistent gap and improves airflow by adjusting the flap's position relative to the wing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a strict rotary motion is used for the leading-edge flap, then the flap can be simply actuated, but the gap between the flap and the wing is not optimized and airflow is affected
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed rotary motion to a variable motion pattern. The scissor mechanism enables the flap to exhibit different motion characteristics at different deployment stages: initial rotational movement followed by translational movement, allowing the gap to be optimized during deployment while maintaining operational simplicity through a single actuator.
Solution Approach 2:
The scissor mechanism acts as an intermediary between the actuator and the flap. It translates the simple rotary motion of the actuator into a complex composite motion of the flap, mediating the interaction to achieve both simple actuation and optimized airflow characteristics through the variable motion pattern.
2Device complexity
If the flap angle is strictly proportional to the lever position, then the kinematics are simple, but the gap shape and airflow are not optimized
Solution Approach 1:
The scissor mechanism introduces dynamic characteristics to the kinematics, allowing the flap angle to vary non-proportionally with the lever position. This enables the gap shape to be optimized during deployment, preventing flow separation while maintaining relatively simple kinematics through the scissor linkage rather than complex control systems.
3Object-affected harmful factors
If additional holding elements are added to influence the gap, then the gap can be optimized, but the device complexity increases
Solution Approach 1:
The patent merges the gap optimization function into the primary actuation mechanism itself. The scissor mechanism is designed such that its geometric configuration inherently controls the gap shape and size during flap deployment, eliminating the need for separate holding elements or additional actuators, thus optimizing the gap while minimizing component count.
Data Source
AI summary
A flap system driving a leading-edge flap between retracted and extended positions comprises a leading-edge flap having first and second flap joints, first and second scissor links, a first connecting link, and an actuator. The actuator couples with either the first scissor link or first connecting link. The first scissor link is rotatable supported on a first fixed point by a first support joint. An end of the first scissor link opposite the first support joint couples with the first flap joint. The first connecting link is rotatably supported on a second fixed point by a second support joint. An end of the first connecting link opposite the second support joint rotatably couples with an end of the second scissor link. An opposite end of the second scissor link couples with the second flap joint. The first and second scissor links are rotatably coupled to form a scissor arrangement.