Thrust Reverser Cylinder Length Reduction via Dynamic Blocking
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Solution Overview
Problem
The existing thrust reverser systems for aircraft nacelles face challenges in designing and integrating cylinders due to their significant length, which complicates resistance to bending, buckling, and fatigue, as well as integration into the nacelle, particularly in areas prone to turbine bursting risks.
Innovation Solution
The thrust reverser system incorporates cylinders that perform a forward stroke to move the variable secondary nozzle backwards and connect it to the movable cowls, allowing a shorter total stroke, reducing cylinder length and stress, and utilizing connecting rods and blocking devices with elastic means for balanced effort distribution and secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the cylinders have a significant stroke to move both the secondary nozzle and movable cowls, then the displacement function is achieved, but the cylinder length increases causing bending, buckling, and fatigue problems
Solution Approach 1:
The movement sequence is segmented into two distinct phases: first the secondary nozzle moves backward (controlled by cylinder forward stroke), then the movable cowls move backward (controlled by cylinder backward stroke). This segmentation allows the cylinder to have a shorter stroke while still achieving the total displacement required for both components.
Solution Approach 2:
The system uses dynamic blocking devices that can alternately lock the secondary nozzle to the fixed structure or lock it to the movable cowls. This dynamic reconfiguration of connections allows the cylinder to control different components at different times, reducing the required stroke length while maintaining full displacement capability.
2Length of moving object
If the cylinders are made longer to achieve the required stroke, then the displacement function is achieved, but the integration into the nacelle becomes complicated and risks projections in turbine bursting areas
Solution Approach 1:
The total displacement requirement is segmented into two sequential movements (nozzle movement + cowl movement) controlled by one cylinder. This allows the cylinder to be positioned in a compact location within the nacelle rather than requiring a long external stroke, simplifying integration and avoiding turbine bursting risk zones.
3Ease of manufacture
If the cylinder stroke is reduced to facilitate design and integration, then the manufacturing ease is improved, but the ability to move both secondary nozzle and movable cowls is compromised
Solution Approach 1:
The blocking devices dynamically reconfigure the mechanical connection between the cylinder, secondary nozzle, and movable cowls. During the forward stroke, the nozzle is unlocked from the cowls and moved by the cylinder. During the backward stroke, the nozzle is locked to the cowls and moved with them. This dynamic reconfiguration ensures full displacement functionality with a shorter cylinder stroke.
Solution Approach 2:
The system maintains continuous useful action by ensuring that during each stroke phase, the cylinder is directly connected to and moving the component that needs displacement. The blocking devices ensure no loss of motion transmission, maintaining 100% efficiency in the displacement function despite the shorter stroke.
Data Source
AI summary
A thrust reverser of a bypass turbojet engine nacelle is disclosed, which includes movable cowls that move backwards with respect to a fixed front structure to uncover thrust reverser cascades and a variable secondary nozzle connected to the movable cowls by guide means allowing an axial sliding of the system which controls the movement of this variable secondary nozzle, wherein it includes cylinders bearing on the front structure for controlling reversal means of the displacement direction connected to the movable cowls, which move the variable secondary nozzle backwards when these cylinders output a forward stroke, as well as blocking devices which connect the secondary nozzle to the movable cowls when this nozzle is deployed.