Aircraft Control Valve Bellows Sealing for High-Pressure Leakage
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Solution Overview
Problem
Existing control valves in aircraft turbine engines face challenges in providing effective sealing under high pressure and high temperature conditions due to leakage through orifices where the rod passes, and current solutions are complex and bulky.
Innovation Solution
A control valve design featuring a tubular bellow and a washer-sealing mechanism around the rod, with a ring and cup structure to ensure dynamic and static sealing, using materials like metallic alloys or composites to maintain contact and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomer O-rings are used for sealing the rod in orifices, then the sealing is simple to implement, but the sealing effectiveness is insufficient under high pressure and high temperature conditions
Solution Approach 1:
The patent employs a bellows-shaped sealing element made of flexible material that can deform elastically to maintain contact with the rod surface. This flexible membrane structure provides reliable sealing under high pressure and temperature by conforming to the rod geometry while remaining simple in construction.
Solution Approach 2:
The sealing mechanism utilizes elastic deformation of the bellows element, changing its physical state from rigid to flexible under operational conditions. The element deforms axially to accommodate rod movement while maintaining sealing contact, adapting its parameters dynamically to maintain effectiveness under extreme conditions.
2Reliability
If a bellows-based sealing system with multiple parts is used, then the sealing reliability improves, but the device becomes complex and bulky
Solution Approach 1:
The patent combines multiple sealing functions into a single integrated bellows element that simultaneously provides dynamic sealing, compensates for rod movement, and maintains contact pressure. This merged structure eliminates the need for separate components while achieving reliable sealing under high pressure and temperature conditions.
Solution Approach 2:
The bellows-shaped sealing element performs multiple functions: it provides dynamic sealing around the rod, compensates for axial movements, maintains contact pressure through elastic deformation, and resists high pressure and temperature. This multi-functional element simplifies the overall sealing system while ensuring reliability.
3Ease of operation
If the rod passes through orifices in the body, then the obturator can rotate freely, but fluid leakage occurs through the orifices
Solution Approach 1:
The bellows-shaped sealing element acts as an intermediary between the rod and the orifice walls, filling the annular gap and preventing fluid leakage. This intermediate sealing element allows the rod to rotate freely while blocking the leakage path through elastic deformation and continuous contact with the rod surface.
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 design provides optimal dynamic sealing, preventing fluid leakage even under extreme conditions, with a compact and efficient sealing mechanism that maintains contact and compensates for wear and thermal expansion.
Implementation Method 1
a tubular bellow mounted around the rod, the tubular bellow being elastically deformable in particular along the axis of rotation
Implementation Method 2
define a stroke of axial deformation of the tubular bellow which is axially preloaded so as to maintain the washer axially against the second shoulder
Data Source
AI summary
A control valve, in particular for an aircraft turbine engine, includes a movable seal which is carried by a rod that passes through ports of a body of the valve. Sealing means are mounted in each of these ports. The sealing means include a tubular bellows mounted around the rod, a ring mounted around the rod and the tubular bellows and at least partially housed in one of the ports, and a washer mounted around the rod. The washer is inserted between the tubular bellows and one end of the ring which bears against the bottom of said port.