Fuel Valve Shuttle Shut-Off for Actuator Jam Fail-Safe
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Solution Overview
Problem
In gas turbine engines, especially those with lean burn combustion, there is a risk of fuel supply continuing when the actuator and valve components become jammed, leading to potential fire hazards or engine damage due to the inability to effectively switch off fuel flow to the combustion chamber.
Innovation Solution
A valve design featuring a shuttle mechanism within the valve body that moves between positions to block or allow fuel flow based on internal pressure thresholds, utilizing a piston and biasing mechanism to ensure safe shut-off when pressure is reached, preventing fuel flow when the actuator fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If actuators are used to open and close ports in a valve to control fuel flow, then fuel supply can be switched on or off, but the system becomes vulnerable to fire hazards and engine damage if the actuator becomes jammed in an open state
Solution Approach 1:
The biasing mechanism applies a preliminary closing force to the shuttle, creating a fail-safe state where the valve defaults to closed position. This preliminary anti-action counteracts any potential jamming in the open state, ensuring that fuel flow is automatically prevented when the actuator fails, thus resolving the reliability concern while maintaining operational control capability
Solution Approach 2:
The valve design enables self-protection through the biasing mechanism that automatically returns the shuttle to the closed position without requiring external intervention. The system serves itself by using the pressure differential and mechanical bias to ensure safe shut-off, eliminating the need for additional safety systems or manual intervention when actuator failure occurs
2Reliability
If a piston and biasing mechanism are added to ensure safe shut-off, then reliability improves, but device complexity increases
Solution Approach 1:
The biasing mechanism is integrated directly into the valve body structure, with the spring housed within the same component envelope as the shuttle and piston. This merging of functions reduces the number of separate assemblies and simplifies manufacturing while maintaining the reliable shut-off capability, thus resolving the complexity concern
Solution Approach 2:
The valve body serves multiple functions: it houses the shuttle, contains the biasing mechanism, provides fluid passages, and structures the piston movement. This multi-functionality reduces the need for additional components and simplifies the overall device structure while ensuring reliable safe shut-off, addressing the complexity issue
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 design ensures safe and controlled fuel delivery, preventing fuel leakage and potential hazards by ensuring the fuel supply can be reliably shut off even if the actuator becomes jammed, thus enhancing engine safety and efficiency.
Implementation Method 1
a biasing mechanism arranged to bias the shuttle towards the first position
Implementation Method 2
the shuttle is moved towards the second position when the fluid within the cavity reaches a threshold pressure
Data Source
AI summary
The disclosure relates to a valve for a fuel system having a body with at least one inlet and one outlet, the inlet fluidly connected to a pressurised fuel source in use. A shuttle is mounted within the body, the shuttle having a cavity of fixed volume and movable between a first position where fluid is permitted to flow through the inlet and is prevented from flowing through the outlet and a second position where fluid is prevented from flowing through the inlet and is permitted to flow through the outlet. A piston is configured to engage the fluid within the shuttle cavity to move the shuttle between the first and second position. A biasing mechanism biases the shuttle towards the first position and where the shuttle moves towards the second position when the fluid within the shuttle reaches a critical pressure.