Aircraft Engine Variable Geometry Jack Testing Without Combustion
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Solution Overview
Problem
Testing equipment with variable geometries in aircraft engines poses challenges due to hydraulic system architecture, including pressure fluctuations and potential blockages during maintenance, which can lead to unsafe conditions and equipment deterioration.
Innovation Solution
A method that controls the fuel dosage and shut-off valves to manage fuel displacement during jack movements without additional equipment, allowing tests to be conducted with the engine shut off, reducing fuel injection and minimizing combustion risks, and ensuring safe and efficient testing of hydraulic actuators and servovalves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started to provide hydraulic pressure for testing jacks, then the hydraulic system can operate, but combustion risks increase and maintenance time increases
Solution Approach 1:
The method performs preliminary actions by controlling fuel dosage and shut-off valves before jack movement to prevent fuel accumulation in the combustion chamber, enabling safe testing without engine startup
Solution Approach 2:
The fuel doser and shut-off valves act as intermediaries to manage fuel flow, preventing fuel from reaching the combustion chamber while maintaining hydraulic pressure for jack operation
2Ease of operation
If the jack rod retracts into the jack, then the jack returns to initial position, but fuel pressure increases and may cause blockage
Solution Approach 1:
The method extracts excess fuel from the hydraulic circuit by directing it to the combustion chamber (which is prevented from actual combustion by the shut-off valve), thereby relieving pressure buildup caused by jack rod retraction
Solution Approach 2:
The method converts the harmful pressure buildup into a beneficial fuel flow path by directing excess fuel through the doser to the combustion chamber, where it is harmlessly contained by the shut-off valve, thus preventing blockage
3Ease of operation
If the jack rod extends out, then the jack actuates equipment, but fuel is displaced and may cause unwanted movement
Solution Approach 1:
The method uses feedback control through position sensors on the jacks to monitor rod extension, and adjusts fuel dosage accordingly through the doser to compensate for volume changes and prevent unwanted fuel movement
4Reliability
If additional equipment is added to manage fuel displacement, then fuel pressure can be controlled, but device complexity increases
Solution Approach 1:
The method makes the existing fuel doser and shut-off valves perform multiple functions: they control fuel dosage for injection and simultaneously manage fuel displacement during jack operation, eliminating the need for additional pressure control equipment
Solution Approach 2:
The hydraulic system uses its own fuel supply mechanism to manage fuel displacement, with the doser and shut-off valves self-regulating pressure without requiring external control systems
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
Enables reliable and safe testing of equipment with variable geometries without engine startup, reducing maintenance costs and time, and preventing equipment deterioration by maintaining constant fuel volume and pressure, thus ensuring operator safety and efficient maintenance operations.
Implementation Method 1
The movement of a jack V is controlled by a servovalve SV which moves the piston of said jack V by connecting a chamber of this jack V to the High-Pressure zone HP
Implementation Method 2
Different servovalves SV for directing the HP or BP pressure from the good side of the mobile elements (jacks VSV or VBV, doser FMV, shut-off valve HPSOV) so as to control them
Data Source
AI summary
The invention relates to a method for testing equipment with variable geometries of an aircraft engine, especially turbomachine. In a first phase, a computer tests the chain of controls of the fuel dosage function. In a second phase, said computer tests the jacks of the chains of controls of equipment with variable geometries by keeping the aircraft shut-off valve open during rod extensions of jacks and by controlling the injection shut-off valve to expel fuel into the injection chamber during their rod retractions.