Variable Pitch Thread Spring System for Aircraft Landing Gear
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Solution Overview
Problem
Aircraft spring systems, particularly in landing gears, face issues with spring deformation and jumping due to uneven thread pitch changes during tensioning, leading to potential plastic deformation and reduced fatigue strength, and existing solutions like pre-cylinders and adhesive connections are either prone to seizure or compromise stability.
Innovation Solution
A spring system with a variable thread pitch that matches the operating pitch of the spring, reducing deformation and force buildup at the clamping point, thereby minimizing the risk of spring jumping and enhancing fatigue strength, while allowing for a shorter eyelet head and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant pitch thread is used to fasten the spring, then the spring can be securely attached to the eyelet head, but the spring deformation and force buildup cause the spring to jump or deform plastically
Solution Approach 1:
The thread pitch is changed from constant to variable, specifically designed to match the spring's operating pitch at different positions. This parameter change allows the thread to accommodate the spring's deformation pattern, reducing stress concentrations and preventing plastic deformation while maintaining secure fastening.
Solution Approach 2:
Different sections of the thread have different pitch characteristics tailored to local requirements. The first thread section has a pitch matching the spring's unloaded pitch for initial engagement, while the second thread section has a pitch matching the spring's operating pitch for the clamping region, creating local quality variations that optimize performance at each location.
2Stability of the object's composition
If pre-cylinders or adhesive connections are used to prevent spring jumping, then spring stability is improved, but the device becomes susceptible to seizure or loses fatigue strength
Solution Approach 1:
The invention replaces mechanical prevention methods (pre-cylinders, adhesives) with a geometric solution based on variable thread pitch. The thread geometry itself prevents spring jumping by matching the spring's deformation characteristics, eliminating the need for additional mechanical components that could cause seizure or reduce fatigue strength.
3Reliability
If a longer eyelet head is used to accommodate constant pitch threading, then the spring can be securely fastened, but the device complexity and material usage increase
Solution Approach 1:
By changing the thread pitch parameter from constant to variable, the eyelet head length is reduced. The variable pitch allows the thread to accommodate spring deformation within a shorter length, reducing material usage and simplifying the overall device structure while maintaining secure fastening.
Data Source
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AI summary
The present invention relates to a spring system for an aircraft, a landing gear for an aircraft comprising at least one spring system and an aircraft, in particular an aeroplane.