Bleed Air Switching Valve Piston Assembly for Seal Wear Reduction
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Solution Overview
Problem
Wear at sealing interfaces in bleed air valves of aircraft engines leads to inefficiencies and potential failures in secondary air systems, which are critical for engine operation and cabin pressurization.
Innovation Solution
A valve design featuring a piston assembly with a sealing ring housed in an annular groove, where the piston body is composed of multiple mating members providing enhanced sealing and reduced wear through radial contraction and expansion capabilities, allowing for effective sealing between high and low-pressure air sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sealing ring is used in a single-piece piston body, then the structure is simple and easy to manufacture, but wear occurs at the sealing interface reducing reliability
Solution Approach 1:
The piston body is divided into multiple segments (first piston body segment, second piston body segment, third piston body segment) that can be assembled together. This segmentation allows the sealing ring to be positioned in a dedicated groove between segments, creating a more reliable sealing interface while maintaining manufacturing feasibility through modular construction.
Solution Approach 2:
The sealing ring acts as an intermediary element between the piston body segments and the sleeve. By placing the sealing ring in a groove formed by the segmented piston body, the sealing function is enhanced without requiring a completely different piston structure, thus resolving the contradiction between manufacturing simplicity and sealing reliability.
2Ease of operation
If a spring-mounted piston with sealing ring is used, then the valve can govern air intake effectively, but wear at sealing interfaces leads to potential failures
Solution Approach 1:
The piston body is segmented into multiple parts that assemble around a central axis, with the sealing ring positioned in a groove between segments. This segmented structure maintains the spring-mounted piston's operational effectiveness while enhancing sealing durability through the modular design that distributes wear and allows for easier replacement of sealing components.
Solution Approach 2:
The sealing ring is positioned in a groove with specific dimensional parameters (radial depth, axial position) that optimize the sealing contact pressure and distribution. By carefully controlling the groove dimensions and the sealing ring's position within it, the sealing effectiveness is improved while maintaining the piston's operational characteristics.
Data Source
AI summary
A valve for an air system in an aircraft engine, comprising: a housing defining a chamber having a valve axis circumscribed by a sealing surface; and a piston assembly within the chamber including: a sealing ring; and a body extending annularly about a piston axis collinear with the valve axis, having a first and a second piston surface axially spaced apart, a radially outer piston surface extending axially and located between the first and second piston surfaces, and an annular groove extending radially inwardly from the radially outer piston surface having first and second groove walls spaced apart and axially facing one another, the sealing ring within the annular groove, the body including: a first member defining the first piston surface and the first groove wall; and a second member defining the second piston surface and the second groove wall, the first member and the second member in mating engagement.