Accessory Gearbox Vibration Monitoring for Jet Engine Fuel Pump Faults
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Solution Overview
Problem
Current systems fail to detect failures in low-pressure fuel pumps of jet engines promptly, leading to potential damage of high-pressure pumps and engine shutdown, as the failure of the low-pressure pump is not directly detectable until its consequences manifest, posing a significant risk to aircraft safety.
Innovation Solution
A device and method that measure the rotation speed of the jet engine's rotary shaft and the vibration frequencies of the accessory relay box using an accelerometer, allowing for the detection of the low-pressure fuel pump's normal vibration frequency, enabling early identification of pump failures and preventing subsequent high-pressure pump deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional monitoring systems are used, then the system complexity remains low, but the detection precision of pump failures is insufficient
Solution Approach 1:
The patent introduces vibration sensors as intermediary devices that indirectly detect pump failures by measuring vibrations transmitted through the drive shaft and accessory relay box. This allows failure detection without direct observation of the pump itself, resolving the contradiction between detection precision and system complexity.
Solution Approach 2:
The patent replaces direct mechanical monitoring of the pump with a vibration-based detection system that uses accelerometers and signal processing electronics. This substitution enables more precise failure detection while maintaining relatively simple system architecture through non-contact measurement.
2Reliability
If the low-pressure pump failure is not detected early, then the monitoring system remains simple, but the high-pressure pump suffers damage
Solution Approach 1:
The patent implements preliminary detection of low-pressure pump failures by monitoring vibration signatures before the failure propagates to damage the high-pressure pump. The system detects abnormal vibrations early in the failure process, enabling preventive action before catastrophic damage occurs.
Solution Approach 2:
The patent establishes a feedback mechanism where vibration sensors continuously monitor the drive shaft and accessory relay box, and the control system responds to detected abnormalities by alerting operators or shutting down the engine, thereby protecting the high-pressure pump from damage.
3Loss of time
If failure detection is delayed until consequences manifest, then the detection system remains simple, but the engine shutdown becomes inevitable
Solution Approach 1:
The patent exploits mechanical vibrations generated by the pump and transmitted through the drive shaft and accessory relay box as a detection signal. By analyzing these vibrations, the system can detect failures in real-time without delay, preventing the need for complex post-consequence detection 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 quick detection of low-pressure fuel pump failures, allowing for timely intervention to prevent damage to the high-pressure pump and avoid engine shutdown, thereby enhancing aircraft safety by anticipating and addressing pump malfunctions before they cause significant damage.
Implementation Method 1
means for measuring vibration frequencies of the accessory relay box and means for detecting, out of said frequencies, at least one normal vibration frequency of the low-pressure fuel pump
Data Source
AI summary
A device for detecting a fault in a low-pressure fuel pump of a turbojet. The pump is driven by an accessory gearbox including a gear for mechanically driving the accessories. The device measures the vibration frequencies of the accessory gearbox and detects, from among the frequencies, at least one vibration frequency of the low-pressure fuel pump. The device allows a fault in the low-pressure fuel pump to be detected as soon as it occurs.