Fuel Metering Valve Feedback for Real-Time Flow Control
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Solution Overview
Problem
Conventional fuel systems for aircraft turbine engines lack real-time measurement and dynamic adjustment of fuel flow rates, leading to lag in response to rapid changes in discharge pressure, resulting in inaccurate metering and potential fuel flow transients.
Innovation Solution
A metered fuel flow feedback system that includes a fuel metering valve, a flow measuring system capable of measuring mass flow rate at a bandwidth greater than 20 Hz, and a controller that dynamically adjusts the valve stroke based on real-time measurements to maintain desired flow rates and reject disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional fuel system uses metering valve position estimation with lookup tables to determine fuel flow, then the system structure remains simple, but the measurement precision and response accuracy deteriorate during rapid pressure changes
Solution Approach 1:
The patent implements a feedback control system where a flow sensor measures actual fuel flow rate and feeds this information back to a controller. The controller compares the measured flow with the desired flow and dynamically adjusts the metering valve position to eliminate any discrepancy. This closed-loop feedback mechanism resolves the contradiction by providing accurate real-time measurement without requiring overly complex system architecture.
Solution Approach 2:
The patent replaces the conventional mechanical estimation method (lookup tables based on valve position) with an electronic measurement and control system. A flow sensor electronically measures actual fuel flow, and a controller processes this data to dynamically adjust valve positioning. This substitution of mechanical estimation with electronic sensing and control achieves superior measurement precision while maintaining reasonable system complexity.
2Stability of the object's composition
If the bypass valve operates to adjust flow and pressure across the metering valve in response to discharge pressure changes, then pressure regulation is maintained, but a time lag occurs between pressure change and corrective action
Solution Approach 1:
The patent implements preliminary action by continuously monitoring actual fuel flow with a sensor before pressure disturbances can significantly affect combustion. The flow measurement provides advance warning of flow deviations, allowing the controller to initiate corrective valve adjustments earlier than the conventional bypass valve response. This proactive approach reduces the effective response time lag while maintaining pressure regulation stability.
Solution Approach 2:
The patent uses real-time flow measurement feedback to detect discharge pressure changes and their effects on fuel flow immediately. This feedback enables the controller to dynamically adjust the metering valve in real-time, significantly reducing the time lag between pressure change and corrective action compared to the slower conventional bypass valve mechanism.
3Speed
If direct feedback measurement of mass flow rate is implemented with bandwidth greater than 20 Hz, then the response speed and accuracy improve, but the device complexity and cost increase
Solution Approach 1:
The patent introduces a flow sensor as an intermediary device that indirectly measures fuel flow characteristics without requiring direct complex measurement of mass flow. The sensor provides electrical signals proportional to flow rate, which the controller then processes to determine actual fuel flow. This intermediary approach achieves high response speed (>20 Hz bandwidth) while keeping the measurement system complexity manageable through the use of standard sensing technology.
Data Source
AI summary
The present disclosure describes a fuel system for an engine. The fuel system includes a fuel metering valve, a flow measuring system, and a controller in communication with the fuel metering valve and the flow measuring system. The fuel metering valve is operable to meter a flow rate of fuel based on a stroke of the fuel metering valve. The flow measuring system is configured to measure a mass flow rate of the fuel leaving the fuel system at a bandwidth greater than 20 Hz. The controller is configured to dynamically adjust the stroke of the fuel measuring system based on the mass flow rate of the fuel measured by the flow measuring system to change the flow rate of the fuel.