Turbojet Nacelle Reverser Flap Deployment System
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Solution Overview
Problem
Conventional deployment systems for reverser flaps in bypass turbojets lack the ability to delay deployment relative to the movement of the movable cowl and often require multiple mechanical members traversing the secondary duct, which can hinder aerodynamics.
Innovation Solution
A deployment system that coordinates and delays the deployment of the reverser flap using a combination of slide bars, guide means, and connecting rods, allowing for offset between cowl translation and flap rotation, thereby reducing mechanical components within the duct and optimizing the cowl's shape for improved aerodynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional deployment system is used for the reverser flap, then the system is simple to implement, but it cannot delay the deployment of the reverser flap relative to the movement of the movable cowl
Solution Approach 1:
The patent employs a dynamic linkage mechanism consisting of slide bars, guide means, and connecting rods that automatically coordinate the timing between movable cowl translation and reverser flap deployment. The linkage transforms the linear motion of the cowl into a delayed rotational motion of the flap through geometric constraints, eliminating the need for external timing control systems while achieving precise deployment sequencing.
Solution Approach 2:
The deployment system introduces an intermediary linkage mechanism between the movable cowl and the reverser flap. This intermediate structure (comprising slide bars and connecting rods) acts as a mediator that translates and delays the motion signal from the cowl to the flap, enabling controlled timing without requiring direct actuation or complex control systems.
2Ease of operation
If multiple mechanical members traverse the secondary duct to deploy the reverser flap, then the deployment function is achieved, but the aerodynamic performance of the nacelle deteriorates
Solution Approach 1:
The patent extracts the deployment mechanism from the interior of the secondary duct and relocates it to the exterior surface of the movable cowl. By mounting the slide bars and connecting rods on the outer surface, the system eliminates the need for mechanical members to traverse through the duct, thereby removing the source of aerodynamic interference while preserving the deployment function.
Solution Approach 2:
The invention moves the deployment mechanism from a three-dimensional space inside the duct to a two-dimensional plane on the external surface of the cowl. This dimensional relocation allows the mechanical components to operate outside the aerodynamic flow path, eliminating drag caused by internal traversing members while maintaining the coupling between cowl motion and flap deployment.
3Reliability
If the movable cowl is made thicker to accommodate conventional deployment mechanisms, then the deployment system is more robust, but the aerodynamic efficiency of the nacelle decreases
Solution Approach 1:
The deployment mechanism is extracted from the internal volume of the movable cowl and mounted on its external surface. This relocation eliminates the need to increase cowl thickness to accommodate internal mechanisms, allowing the cowl to maintain a thin, aerodynamically optimized profile while still providing a robust mounting structure for the deployment system.
Data Source
AI summary
A bypass turbojet nacelle comprising a fixed structure, a fixed cowl and a cowl movable in translation between advanced and withdrawn positions by a ram with a reverser flap movable thereon, and a deployment system comprising a first slider integral with the movable cowl, a first groove comprising a first part and a curved, second part integral with the fixed structure, a second slider movable in translation in the second groove part, a first connecting rod rotatable on the first slider and on the second slider, and a second connecting rod articulated on both the first connecting rod first end and the reverser flap. The ram rod is articulated on the first connecting rod. Moving the first slider from the advanced to the withdrawn position moves the second slider along the first part and, when the first slider reaches the withdrawn position, the second slider moves along the second part.