U-Shaped Leaf Spring for Aircraft Thrust Reverser Shutter
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Solution Overview
Problem
Existing springs for thrust reverser shutters in aircraft turbojet engines are heavy and do not optimize elastic behavior for a given mass, failing to adequately compensate for tolerance deviations and structural deformations.
Innovation Solution
A U-shaped leaf spring with tapered sections and fork-shaped ends, made from titanium alloy or composite materials, which reduces mass and weight while maintaining effective elastic behavior and structural support by eliminating the need for additional bearing pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional helical or blade springs are used for thrust reverser shutters, then the spring can provide necessary elastic behavior and compensate for tolerance deviations, but the spring mass is excessive
Solution Approach 1:
The spring is divided into two distinct branches (first and second branches) that are interconnected, allowing each branch to be optimized independently for weight reduction while maintaining overall elastic functionality
Solution Approach 2:
The spring adopts a U-shaped configuration with curved branches instead of traditional helical or blade forms, reducing mass while maintaining elastic behavior through the curved geometry that distributes bending moments more efficiently
2Weight of moving object
If the spring branches have uniform section throughout their length, then the structure is simple to manufacture, but the mass cannot be reduced
Solution Approach 1:
The spring branches feature varying cross-sections along their length, with different sections optimized for their specific functional requirements, allowing mass reduction in less critical areas while maintaining strength where needed
Solution Approach 2:
The cross-sectional parameters of the spring branches are varied along their length to optimize the strength-to-weight ratio, with sections designed to have different thicknesses or widths based on local stress requirements
3Weight of moving object
If additional bearing pieces are added to support the connecting rod, then the structural support is improved, but the overall mass increases
Solution Approach 1:
The bearing function is integrated directly into the spring structure through returns formed in the mass of the spring, eliminating the need for separate bearing pieces and reducing overall mass while maintaining structural support
Solution Approach 2:
The spring structure serves multiple functions simultaneously: providing elastic behavior for tolerance compensation, structural support for the connecting rod, and bearing support through integrated returns, eliminating the need for separate components
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 U-shaped leaf spring achieves a significant weight reduction of up to 1800 grams per thrust reverser, improving elastic performance and reducing material costs, while maintaining sufficient pressure on flaps to ensure proper operation.
Implementation Method 1
the ends of this spring are subjected to weak or zero bending moments, which allows to have a spring which, for a given mass, has a better elastic behavior
Data Source
AI summary
This leaf spring (17) for a thrust reverser shutter (13) is noteworthy in that it has two branches (19, 21) defining a U shape, the ends (19a, 19b, 21a, 21b) of these branches being able to cooperate respectively with a shutter (13) of said reverser and with a link (15) for actuating this shutter.