Valve Manifold Eutectic Plug Venting for Fire-Safe Servo Closure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft engine bleed air system servo valves fail unpredictably in extreme heat conditions, causing shutoff valves to remain open during engine fires, which can lead to compressor gases reaching critical subsystems.
Innovation Solution
A valve assembly with a manifold featuring a eutectic plug that melts and vents the manifold exhaust conduit during a fire, ensuring the servo valve closes by eliminating pressure, and includes heat fins for thermal management and a thermal spacer for reduced conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the servo valve is exposed to extreme heat conditions, then the valve operates in high temperature environment, but the valve fails unpredictably and remains open during engine fires
Solution Approach 1:
The eutectic plug is pre-installed in the exhaust conduit to seal it before any fire event occurs. This preliminary sealing action ensures that during normal operation the conduit remains closed, but during a fire the plug will melt at a predetermined temperature to vent the conduit and close the servo valve, preventing compressor gases from reaching critical subsystems
Solution Approach 2:
The eutectic plug material is selected with a specific melting point parameter that corresponds to fire conditions. This parameter change from solid to liquid state at the eutectic temperature enables the plug to transition from sealing the exhaust conduit to venting it, thereby triggering the servo valve closure mechanism when temperature exceeds safe operating limits
2Stress or pressure
If the manifold exhaust conduit is sealed to maintain pressure, then pressure is maintained for valve operation, but during a fire the pressure prevents servo valve closure
Solution Approach 1:
The eutectic plug utilizes phase transition from solid to liquid at a predetermined temperature to change the sealing state of the exhaust conduit. During normal operation, the solid plug maintains the seal and pressure. During a fire, the phase transition to liquid state creates an opening that vents the conduit, allowing atmospheric pressure to act on the servo valve diaphragm and force closure, thus resolving the contradiction between maintaining pressure for operation and enabling safe shutdown
3Temperature
If heat is dissipated from the manifold, then thermal management is improved, but the eutectic plug must withstand temperature gradients
Solution Approach 1:
The eutectic plug is positioned specifically at the exhaust conduit where it needs to sense fire temperature, while heat fins are strategically placed on the manifold body to dissipate heat from critical components. This local differentiation allows the plug to experience the necessary temperature rise for fire detection while other parts of the manifold remain thermally managed, maintaining material integrity where needed
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 solution ensures predictable operation of shutoff valves by maintaining the servo valve's functionality during extreme conditions, preventing compressor gases from reaching critical subsystems in the event of an engine fire.
Implementation Method 1
a plug disposed within the manifold exhaust conduit at the manifold exhaust port, wherein the plug is formed of a eutectic material
Implementation Method 2
heat fins extend radially outward from the manifold exhaust conduit between the manifold inlet body portion and the manifold exhaust port
Implementation Method 3
heat fins extend radially outward from the manifold exhaust conduit
Implementation Method 4
a thermal spacer between the manifold and the valve body
Data Source
AI summary
Disclosed is a valve assembly with: a valve body defining valve inlet and outlet ports; a manifold connected to the valve outlet port, the manifold includes: a manifold inlet body portion defining: a manifold internal surface forming a manifold channel; and a first manifold external surface defining a manifold inlet opening that opens to the manifold channel, the manifold channel is fluidly coupled to the valve outlet port via the manifold inlet opening; a manifold outlet port, and a manifold outlet conduit extending from the manifold inlet body portion to the manifold outlet port; a manifold exhaust port, and a manifold exhaust conduit extending from the manifold inlet body portion to the manifold exhaust port, the manifold exhaust and outlet conduits are fluidly coupled to each other via the manifold channel, heat fins extend from the manifold exhaust conduit; and a eutectic plug disposed within the manifold exhaust conduit.