Aircraft Fuel Return Valve Failure Detection via Pressure and Speed
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Solution Overview
Problem
Conventional aircraft engine fuel circuit architectures face performance degradation due to potential malfunctions in the motive flow valve, which can cause unintended fuel flow to the jet pump, reducing engine fuel pressure during startup phases.
Innovation Solution
A method involving a pressure sensor and a calculator to measure fuel pressure and engine speed, detecting valve failures by comparing pressure thresholds and engine speed, without requiring a dedicated position sensor on the valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motive flow valve is used to control fuel return to the jet pump, then fuel pressure can be maintained during startup phases, but the valve may malfunction and stay blocked in open position causing performance degradation
Solution Approach 1:
The patent implements a feedback mechanism where the calculator continuously monitors engine speed and compares it against threshold values to determine the expected valve state. When the actual fuel pressure or valve position deviates from the expected state based on feedback from speed sensors, the system detects a malfunction and can alert the pilot or activate backup systems, ensuring reliable operation despite potential valve failures.
Solution Approach 2:
The patent replaces direct mechanical position sensing of the valve with an indirect detection system using electronic sensors and a calculator. Instead of mechanically linking the valve position to a sensor, the system uses speed sensors and pressure measurements combined with logical comparison in the calculator to infer valve state, reducing mechanical complexity and potential failure points while maintaining reliability.
2Reliability
If a dedicated position sensor is installed on the valve to detect failures, then valve malfunction can be detected, but device complexity increases
Solution Approach 1:
The patent makes the existing calculator and sensor system perform multiple functions: it not only controls the fuel management system but also detects valve failures by comparing speed data with expected valve states. This multi-functionality eliminates the need for dedicated failure detection sensors, reducing overall system complexity while maintaining high reliability through the same computational resources already present in the aircraft's fuel management system.
Solution Approach 2:
The system uses its own existing sensors and processing capabilities to monitor its own operational state. The calculator, which already processes data from speed sensors for fuel management, now also performs self-diagnosis by comparing actual valve position with expected position based on engine speed, enabling the system to detect its own malfunctions without external monitoring equipment.
3Ease of operation
If fuel is sent to the jet pump during startup phases, then the jet pump can operate, but engine performance degrades due to reduced fuel flow to the engine
Solution Approach 1:
The patent implements dynamic control of the motive flow valve based on real-time engine speed conditions. The valve automatically transitions between closed and open positions according to predefined speed thresholds, ensuring that fuel is diverted to the jet pump only when the engine is running at sufficient speed and does not need maximum fuel supply. This dynamic adaptation optimizes fuel distribution between the engine and jet pump based on operational requirements, maintaining both ease of operation and productivity.
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
Effectively detects motive flow valve failures, preventing performance degradation by identifying when fuel pressure drops below a threshold at specific engine speeds, ensuring proper valve operation and maintaining optimal engine fuel supply.
Implementation Method 1
a jet pump 12 operating using the Venturi effect, is also immersed in the tank 10 and makes it possible to take over from the aircraft pump under certain conditions
Data Source
AI summary
A method for detecting a failure in a fuel return valve of an aircraft engine fuel circuit, the fuel circuit including a fuel tank, an engine fuel system connected to the fuel tank capable of delivering a flow of fuel to the engine depending on a speed of the engine, a fuel return pipe connected between the engine fuel system and the fuel tank, a fuel return valve arranged to switch between an open and closed position, the valve being capable of blocking the fuel return pipe in the closed position, and of bringing the fuel return pipe into communication with the fuel tank in the open position, the method including measuring a pressure of the flow of fuel from the fuel tank, and if the measured pressure is lower than a predefined threshold, measuring the engine speed.