Three-Piece Piston Assembly for Load and Wear Control
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Solution Overview
Problem
Aircraft thrust reverser actuation systems face challenges in maintaining synchronization and withstanding increasing loads while being lightweight and economical, as traditional piston designs are costly and difficult to manufacture, and current solutions lead to damage from sudden aerodynamic forces during deployment.
Innovation Solution
A three-piece piston assembly is designed, where each piece can be made from different materials optimized for strength, friction reduction, and wear resistance, using a hydraulic valve to control fluid flow and mitigate deployment impacts, and assembled using conventional manufacturing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional one-piece piston is used, then the structure is simple, but the manufacturing cost is high and it is difficult to manufacture
Solution Approach 1:
The piston is divided into multiple separate pieces (piston body, lock nut, and locking feature components) that can be manufactured independently using conventional techniques and then assembled together. This segmentation allows each component to be optimized for its specific function and manufactured more easily than a single complex one-piece structure.
2Strength
If the locking feature is machined into the piston, then the strength is high, but the manufacturing cost increases and manufacturing becomes difficult
Solution Approach 1:
The locking feature is separated from the main piston body into a distinct component (lock nut with locking feature). This allows the locking feature to be manufactured as a separate, simpler part that can be produced more easily while maintaining its structural integrity and strength requirements.
3Reliability
If a single material is used for the piston, then the manufacturing is simpler, but the performance cannot be optimized for different functions
Solution Approach 1:
Different portions of the piston assembly use different materials optimized for their specific functions: the piston body uses a material suitable for hydraulic pressure containment, the lock nut uses a material optimized for threading and locking engagement, and the locking feature uses a material with appropriate wear and strength characteristics. This local optimization enhances overall reliability.
Solution Approach 2:
The piston assembly employs multiple materials in combination rather than a single material throughout. Each component is selected from appropriate material families (metals, alloys, or composite materials) based on its specific functional requirements, creating a multi-material assembly that achieves superior overall performance.
4Strength
If the lock nut material achieves both high strength and low friction, then the load holding capability is improved, but the manufacturing cost increases
Solution Approach 1:
The lock nut is designed with different surface characteristics in different areas: the threading surfaces are optimized for strength and load bearing, while the friction surfaces are treated or selected to provide low friction. This localized optimization allows the use of conventional materials with appropriate surface treatments rather than requiring expensive specialized materials throughout.
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 three-piece piston assembly provides improved load capability, reduced friction, and enhanced wear properties, while maintaining synchronization and reducing manufacturing costs, effectively addressing the challenges of increased aircraft loads and deployment forces.
Implementation Method 1
using a hydraulic valve to control fluid flow and mitigate deployment impacts
Data Source
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AI summary
The subject matter of this specification can be embodied in, among other things, an assembly that includes a piston having a piston inner surface defining a cylindrical cavity and includes a first axial portion, a piston face at a first end of the first axial portion, a second axial portion at a second end of the first axial portion, and a helical piston thread defined upon the piston inner surface, a bushing configured to contact the piston inner surface, and a lock nut configured to engage the piston and the bushing.