Aircraft Piston Segmentation for Weight and Wear
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Solution Overview
Problem
Current steering actuator pistons for aircraft landing gear, typically made of bronze, are cumbersome and require scrapping if production defects or in-service wear exceed specifications, leading to inefficiencies in material usage and maintenance.
Innovation Solution
The piston is constructed with a lightweight alloy for the main body and a bronze sleeve, allowing for adjustable external diameter and reduced material loss in case of defects or wear, utilizing a cylindrical and externally threaded design with a bronze sleeve and seal for hydraulic actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the piston is made entirely of bronze, then the material strength and wear resistance are improved, but the weight increases and material waste occurs when defects or wear exceed specifications
Solution Approach 1:
The piston is divided into two distinct parts: a light alloy body and a bronze sleeve. The bronze sleeve is a separate component that can be independently replaced, allowing the lightweight structure to be maintained while providing wear resistance only where needed (at the cylinder interface). This segmentation resolves the contradiction by localizing the heavy material to only the necessary area.
Solution Approach 2:
The bronze material is applied locally only to the sleeve that contacts the cylinder, rather than the entire piston. This localized application of high-strength, wear-resistant material provides the necessary durability at the critical interface while keeping the rest of the piston lightweight. The light alloy body provides sufficient strength for structural requirements without the excess weight of full bronze construction.
2Reliability
If the piston is made entirely of bronze, then the durability is improved, but the manufacturing cost and maintenance cost increase due to scrapping entire pistons
Solution Approach 1:
The bronze sleeve is designed as a separable component from the light alloy body, connected via threaded engagement. This segmentation allows the sleeve to be independently replaced when worn or defective, rather than scrapping the entire piston assembly. The threaded connection enables straightforward installation and removal, making maintenance cost-effective.
Solution Approach 2:
The design enables selective discarding of only the worn bronze sleeve while retaining the light alloy body. This partial replacement strategy recovers the majority of the piston structure, reducing material waste and maintenance costs compared to replacing entire bronze pistons, while still ensuring durability through periodic sleeve replacement.
3Adaptability or versatility
If the piston outside diameter is adjusted in production, then the adaptability is improved, but the entire piston must be scrapped if specifications are not met
Solution Approach 1:
The bronze sleeve serves as an adjustable outer diameter component that can be manufactured to precise specifications and fitted to the light alloy body. If the required outside diameter changes, only the sleeve needs to be replaced rather than the entire piston. This segmentation allows flexible adaptation to different specifications while minimizing material waste.
Solution Approach 2:
The threaded connection between the bronze sleeve and light alloy body provides adjustability and reconfigurability. The sleeve can be removed and replaced with different sized sleeves to meet varying specification requirements, making the piston system dynamic and adaptable rather than fixed. This enables cost-effective adaptation without scrapping the main piston body.
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
This solution results in a lighter piston that minimizes material waste and allows for cost-effective maintenance by replacing only the defective bronze sleeve, rather than the entire piston, while maintaining hydraulic efficiency.
Implementation Method 1
A bronze sleeve (14) is screwed onto the main part (11). The external diameter of the sleeve bronze 14 is adjusted with a slight clearance to the inside diameter of the cylinder (8). The bronze sleeve (14) has a groove (16) to receive a seal (17) which seals the chamber (9).
Implementation Method 2
A hydraulic port (10) makes it possible to inject into the chamber (9) or recover in from this chamber a flow of hydraulic fluid. The two hydraulic chambers (9) thus constituted define a double-acting hydraulic actuator making it possible to move the rack (6) in one direction or the other.
Data Source
Figure 1~2
AI summary
The invention relates to a steering actuator piston with a rack (6) for an aircraft landing gear (1). The piston comprises a body (18) made of light alloy having an externally threaded main section (11) ending at one end in a shoulder (12) and extended on the other end by a skirt (13), the body (18) having screwed to it a tapped bronze bushing (14) which on its external wall has at least one groove (16) to house a seal (22), the skirt having a drilling to accept a pin (15) that attaches the piston to the rack, the bushing (14) when in service extending between the shoulder and the pin (15) so that it is retained axially between the shoulder (12) and the pin (15).