Hydraulic Thrust Reverser Return Lines for Check Valve Failure Safety
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Solution Overview
Problem
Existing hydraulic thrust reverser actuation systems lack effective redundancy and fail-safe mechanisms to prevent accidental deployment due to check valve failures, which can lead to over-pressurization and unsafe operation.
Innovation Solution
The system incorporates dual return lines with check valves and a flow restrictor that allows fluid to bypass a failed check valve, slowing down fluid flow and enabling detection of failures, while maintaining system safety through isolation control valves and actuator locks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If check valves are used to prevent backflow in return lines, then system safety is improved, but the system becomes vulnerable to over-pressurization if a check valve fails
Solution Approach 1:
A flow restrictor is introduced as an intermediary component in the return line to modulate fluid flow. When a check valve fails, the flow restrictor prevents uncontrolled backflow while allowing controlled return of hydraulic fluid, thereby preventing over-pressurization while maintaining safety functionality.
Solution Approach 2:
The flow restrictor is pre-installed in the return line to provide a safety cushion against potential check valve failures. This component ensures that even if a check valve fails, the system cannot experience catastrophic over-pressurization because the flow restrictor limits the maximum flow rate and pressure buildup.
2Reliability
If dual return lines with check valves are implemented, then redundancy is improved, but system complexity increases
Solution Approach 1:
The hydraulic system is segmented into two independent return lines, each with its own check valve and flow restrictor. This segmentation provides redundancy - if one line fails, the other can still function - while keeping each segment relatively simple in design and operation.
Solution Approach 2:
Each return line is equipped with locally-specific safety components (check valve and flow restrictor) tailored to its function. This allows each line to be optimized independently, maintaining simplicity in each local segment while achieving overall system redundancy.
3Reliability
If flow restrictors are added to prevent over-pressurization, then system safety is improved, but fluid flow speed decreases
Solution Approach 1:
The flow restrictor is designed to provide partial restriction under normal conditions, allowing sufficient flow speed for system operation, while providing excessive restriction (safety protection) only when needed during check valve failure scenarios. The restrictor sizing balances normal performance with safety requirements.
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
This design ensures safe operation by detecting check valve failures, preventing over-pressurization, and allowing controlled fluid flow, thereby enhancing the reliability and safety of thrust reverser actuation systems.
Implementation Method 1
Each of the first and second return lines may have a check valve associated therewith, such that fluid can flow through the check valve in only one direction
Implementation Method 2
The first and second return lines may be in fluid communication with one another via a flow restrictor upstream of the check valves
Data Source
Figure 1
Figure 2
AI summary
A hydraulic thrust reverser system (TRAS) (100) including a first return line (144a) having a first check valve (142a) therein, and a second return line (144b) having a second check valve (142b) therein, wherein the first return line (144a) and the second return line (144b) are in fluid communication with each other via a fluid restrictor (146) located upstream of the first and second check valves (142a,b), wherein the first return line (144a) extends from a piston system of the TRAS, the piston system being for moving at least one thrust reverser door (122a,b), and wherein the second return line (144b) extends from a lock system of the TRAS, the lock system being for controlling locks to selectively prevent the movement of the at least one thrust reverser door (122a,b).