Fuel Flow Control Shuttle for Aircraft Metering
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Solution Overview
Problem
Conventional differential pressure relief valves in aircraft fuel metering systems provide imperfect pressure control due to their one-size-fits-all approach, leading to inaccuracies in fuel delivery across varying engine conditions and pump efficiencies.
Innovation Solution
A fuel flow control system with a flow control shuttle having tapered needles in two nozzles, which simultaneously adjusts fuel flow to the engine and bypass, using sensors to monitor pressure and temperature for precise control, eliminating the need for a separate differential pressure relief valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional differential pressure relief valve is used to maintain pressure in the fuel metering system, then the pressure control is simplified, but the accuracy of fuel metering deteriorates due to the one-size-fits-all approach that cannot adapt to varying engine conditions and pump efficiencies
Solution Approach 1:
The patent applies dynamics by replacing the static, fixed-pressure relief valve with a dynamic control system that continuously adjusts the relief pressure based on real-time sensor feedback. The controller modifies the relief pressure setpoint according to engine operating conditions, fuel temperature, and pump performance, enabling the system to adapt to varying conditions and maintain accurate fuel metering across different operational states.
Solution Approach 2:
The patent implements feedback by using sensors to continuously monitor actual relief pressure, fuel temperature, and engine parameters, then feeding this information back to the controller. The controller compares actual pressure with target pressure and adjusts the relief valve accordingly, creating a closed-loop control system that maintains precise pressure control and improves fuel metering accuracy under varying conditions.
2Measurement precision
If the relief pressure is adjusted to compensate for pump wear or deficiency, then the fuel delivery accuracy improves, but the system complexity increases due to the need for dynamic adjustment mechanisms and sensors
Solution Approach 1:
The patent applies self-service by enabling the system to automatically detect and compensate for pump wear or deficiency without external intervention. The sensors continuously monitor pressure and flow characteristics, and the controller autonomously adjusts the relief pressure setpoint to maintain accurate fuel delivery, eliminating the need for manual calibration or external adjustment mechanisms.
Solution Approach 2:
The patent implements parameter changes by dynamically modifying the relief pressure setpoint based on detected pump conditions, fuel temperature, and engine operating parameters. The controller adjusts this critical parameter in real-time to compensate for pump wear, ensuring consistent fuel delivery accuracy across the pump's service life without requiring physical modifications to the pump itself.
3Reliability
If a separate differential pressure relief valve is used alongside the metering valve, then the pressure regulation function is provided, but the system complexity and number of components increases
Solution Approach 1:
The patent applies merging by integrating the pressure regulation function into the existing metering valve assembly, eliminating the need for a separate differential pressure relief valve. The controller manages pressure control through electronic means within the same housing, combining multiple functions (metering and pressure regulation) into a single integrated unit, thereby reducing component count while maintaining reliability.
Solution Approach 2:
The patent implements multi-functionality by designing the metering valve assembly to perform multiple functions: fuel metering, pressure regulation, and temperature compensation. The controller serves multiple purposes by managing flow control, pressure control, and adaptive calibration, reducing the need for separate dedicated components and simplifying the overall system architecture.
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 solution enhances the accuracy and reduces complexity by dynamically adjusting fuel flow based on engine conditions and pump performance, maintaining optimal pressure and flow rates without additional relief valves.
Implementation Method 1
The differential pressure relief valve maintains a precise and nominally constant pressure drop across the metering valve
Implementation Method 2
movement of the flow control shuttle controls flow through the first nozzle and the second nozzle simultaneously, such that the flow control shuttle simultaneously modifies the flow to the gas turbine engine system and the flow to the fuel bypass
Data Source
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AI summary
A fluid flow control system (10) includes a fluid inlet (14), a central chamber (16), a first nozzle (18) extending from a first side of the central chamber and comprising a first throat (42), a second nozzle (20) extending from a second side of the central chamber opposite the first side and comprising a second throat (60), and a flow control shuttle (22). The flow control shuttle includes a first needle (48) having a first tapered portion (50) positioned within the first throat (42) for controlling flow through the first nozzle (18) and a second needle (54) having a second tapered portion (56) positioned within the second throat (60) for controlling flow through the second nozzle (20).