Brake Control Valve Pressure Monitoring for Stuck-Open Shut Off Valves
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Solution Overview
Problem
Aircraft brake systems face safety issues due to uncommanded braking caused by shut off valve failure, which can occur when the valve remains stuck in an open position, leading to unintended braking during takeoff.
Innovation Solution
A brake control valve module (BCVM) with a pressure sensor in fluid communication with the shut off valve and servovalves, which detects pressure changes and sends alerts to an emergency notification system when the pressure exceeds a threshold and a brake signal is not received within a specified period, thereby identifying shut off valve failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shut off valve is used in the brake control system, then the system can control hydraulic pressure flow, but the valve may fail and remain stuck in an open position causing uncommanded braking
Solution Approach 1:
The pressure sensor continuously monitors hydraulic pressure upstream of the shut off valve before the valve is actuated, enabling early detection of valve failure in the open position. This preliminary monitoring allows the system to identify potential uncommanded braking conditions before they occur, resolving the reliability issue by providing advance warning of valve malfunction.
Solution Approach 2:
The system implements feedback through the pressure sensor that continuously reports pressure conditions to the control unit. When pressure remains high indicating the valve is stuck open, the system can provide feedback alerts to pilots or automatically activate alternative braking mechanisms, preventing uncommanded braking and improving overall system reliability.
2Difficulty of detecting and measuring
If a pressure sensor is added to detect valve failure, then detection capability is improved, but device complexity increases
Solution Approach 1:
The pressure sensor serves as an intermediary device that indirectly detects valve failure by monitoring hydraulic pressure conditions rather than directly sensing valve position. This intermediary approach simplifies detection by using a readily available pressure measurement point upstream of the valve, avoiding the need for complex direct valve position sensors or additional mechanical linkages.
Solution Approach 2:
The existing hydraulic pressure system serves dual purposes: it both actuates the brake valves and provides the measurement medium for failure detection. The pressure sensor utilizes the same hydraulic fluid pressure that drives the valve operation, eliminating the need for separate detection systems and reducing overall device complexity while maintaining effective monitoring capability.
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 detects shut off valve failures and alerts the notification system, preventing uncommanded braking and ensuring aircraft safety by providing timely notifications of potential safety hazards.
Implementation Method 1
a pressure sensor disposed within the housing in fluid communication with the shut off valve and the first servovalve
Implementation Method 2
a solenoid is coupled to the housing at the solenoid port, and the solenoid is configured to receive the pressurized fluid from the supply port and is configured to supply the pressurized fluid to the shut off valve
Implementation Method 3
Some servovalves provide hydraulic pressure based on proportional control signal
Data Source
AI summary
Systems and methods for shut off valve failure detection are provided. The system may comprise a housing, a shut off valve disposed within the housing, a first servovalve and a second servovalve coupled to the housing, and a pressure sensor disposed within the housing in fluid communication with the shut off valve. A controller may receive a pressure signal from the pressure sensor in the system, and a brake signal from a brake input device. The controller may determine whether there has been a shut off valve failure in the system in response to the pressure signal being greater than a pressure threshold and the controller failing to receive the brake signal, for a threshold period. The controller may then send a signal to a notification system in response to detection of the shut off valve failure and output a shut off valve failure notification.