Landing Gear Servo Valve Health Monitoring by Pressure Feedback
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Solution Overview
Problem
Aircraft landing gear servo valves experience performance degradation and improper function due to wear, which is not effectively monitored by existing systems, leading to potential safety issues during landing or rejected takeoff.
Innovation Solution
A system and method for monitoring the health of electrohydraulic servo valves in aircraft landing gear, involving a brake control unit that determines pressure thresholds based on current pressure signals, compares actual pressure to these thresholds, and outputs alerts for deviations, using a valve monitoring sensor to measure pressure and flow rate in the conduit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing monitoring systems are used for servo valves, then the system complexity is low, but the reliability of detecting wear and performance degradation is insufficient
Solution Approach 1:
The patent implements a feedback-based monitoring system where the brake control unit continuously receives pressure signals from the servo valve, compares actual pressure against expected pressure thresholds, and generates alerts when deviations indicate wear or performance degradation. This closed-loop feedback mechanism enables reliable detection of valve health status without requiring complex external monitoring equipment.
Solution Approach 2:
The brake control unit performs self-diagnosis by using its own existing pressure sensing capabilities to monitor servo valve health. The system leverages the pressure signals already present in the brake system to detect valve wear, eliminating the need for separate dedicated monitoring sensors or complex additional hardware.
2Reliability
If no monitoring system is implemented, then the device complexity remains low, but the safety during landing or rejected takeoff is compromised
Solution Approach 1:
The system performs preliminary detection of servo valve wear by continuously monitoring pressure deviations before they lead to brake system failure. The brake control unit compares actual pressure against expected thresholds in advance, generating early warnings that allow maintenance to be performed before safety is compromised during critical operations like landing or rejected takeoff.
Solution Approach 2:
The patent uses pressure deviation as an intermediary indicator to infer servo valve health status. Instead of directly measuring wear or valve performance, the system monitors the relationship between commanded pressure and actual pressure, using this pressure differential as a mediator to detect valve degradation while maintaining system simplicity.
3Measurement precision
If threshold-based monitoring is used, then the measurement precision is sufficient for detecting wear, but the complexity of determining dynamic thresholds increases
Solution Approach 1:
The patent implements dynamic threshold determination where the brake control unit adjusts expected pressure thresholds based on operating conditions such as brake command signals and flight phase. The thresholds are not fixed but adapt to changing system requirements, enabling precise wear detection across different operational scenarios without requiring complex lookup tables or extensive calibration data.
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
The system effectively monitors the health of electrohydraulic servo valves by detecting wear and fluid flow issues, enabling timely maintenance and preventing performance degradation, thus ensuring safe aircraft operations.
Implementation Method 1
a valve monitoring sensor coupled to the conduit and configured to measure at least one of a pressure or a fluid flow in the conduit
Implementation Method 2
comparing the pressure in the conduit to an upper pressure threshold and a lower pressure threshold
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A system for monitoring an electrohydraulic servo valve (140) may comprise a brake control unit (30), a valve monitoring sensor (150) configured to measure a pressure in a conduit (206) fluidly connected to a control port of the electrohydraulic servo valve, and a tangible, nontransitory memory (110) configured to communicate with the brake control unit. The brake control unit may be configured to receive a brake command, output a pressure signal to the electrohydraulic servo valve based on the brake command, receive a sensor signal from the valve monitoring sensor, and determine a health of the electrohydraulic servo valve based on the sensor signal.