Limited-Flow Thrust Reverser Actuation With Bypass Fluid Supply
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Solution Overview
Problem
Conventional thrust reverser actuation systems for aircraft engines face challenges in limiting fluid flow demand, which exceeds the capacity of the onboard hydraulic pump in new aircraft designs, leading to inefficiencies and potential performance issues.
Innovation Solution
The proposed solution involves a fluid control system that includes an electrohydraulic servo valve and a bypass fluid line, along with an isolation control unit and anti-cavitation check valve, to selectively route fluid and limit flow demand by supplementing primary fluid flow with secondary flow from a fluid return reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional thrust reverser actuation systems are used, then the thrust reverser can be deployed, but the fluid flow demand exceeds the capacity of the onboard hydraulic pump
Solution Approach 1:
The fluid supply system is segmented into two independent sources: a primary pressurized fluid source and a secondary fluid return reservoir. The electrohydraulic servo valve selectively routes fluid from either source to the hydraulic actuator, allowing the system to meet high flow demands during thrust reverser deployment without overloading the primary pump.
Solution Approach 2:
The electrohydraulic servo valve acts as an intermediary control device that manages fluid flow between multiple sources and the actuator. It selectively opens or closes fluid passages based on deployment requirements, enabling flexible flow allocation that prevents the primary pump from being overloaded while ensuring sufficient fluid supply for rapid deployment.
2Reliability
If the fluid flow demand is limited to match pump capacity, then the pump is protected from overload, but the thrust reverser deployment time increases
Solution Approach 1:
The system dynamically adjusts fluid flow allocation based on operational requirements. During thrust reverser deployment, the electrohydraulic servo valve opens passages to the fluid return reservoir, temporarily increasing total flow capacity to meet rapid deployment needs. During normal operation, the system returns to limited flow mode to protect the pump, achieving both rapid deployment capability and pump protection.
Solution Approach 2:
The fluid return reservoir is pre-charged with hydraulic fluid, creating a ready-to-deploy fluid source. When deployment is required, the electrohydraulic servo valve immediately routes fluid from the reservoir to supplement the primary pump, eliminating the need to wait for the pump to build pressure or capacity.
3Quantity of substance
If regenerative-type directional control valves are used to recirculate fluid, then flow demand is reduced, but the flow demand still exceeds pump capacity in certain new aircraft designs
Solution Approach 1:
The system creates a copy of the hydraulic fluid supply by utilizing the fluid return reservoir as a secondary source. Instead of merely recirculating fluid through regenerative valves, the system has a dedicated backup fluid source that can be independently activated to meet high flow demands, providing a more robust solution to the flow capacity limitation.
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 approach effectively limits the fluid flow demand on the hydraulic pump, ensuring that the thrust reverser can be deployed within the required time without exceeding the pump's capacity, thus improving the system's efficiency and performance.
Implementation Method 1
an electrohydraulic servo valve operable to selectively route fluid between a pressurized fluid source, the hydraulic actuator, and a fluid return reservoir
Implementation Method 2
a bypass fluid line providing fluid communication between the hydraulic actuator and the fluid return reservoir independent of the electrohydraulic servo valve
Implementation Method 3
a piloted check valve operable in a first stage, where fluid flow from the fluid return reservoir to the hydraulic actuator through the bypass fluid line is inhibited, and a second stage, where fluid flow from the fluid return reservoir to the hydraulic actuator is permitted
Implementation Method 4
an anti-cavitation check valve residing on the bypass fluid line, the anti-cavitation check valve configured to permit fluid flow from the fluid return reservoir to the hydraulic actuator, while inhibiting fluid flow from the hydraulic actuator to the fluid return reservoir
Implementation Method 5
a hydraulic actuator operably coupled to move the thrust-reversing element between the stowed position and the deployed position
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, an engine assembly includes a nacelle configured to at least partially surround an engine, and a thrust reverser coupled to the nacelle, the thrust reverser having a thrust-reversing element movable relative to the nacelle between a stowed position and a deployed position, a hydraulic actuator operably coupled to move the thrust-reversing element between the stowed position and the deployed position, and a fluid control system configured to operate the hydraulic actuator, the fluid control system having an electrohydraulic servo valve operable to selectively route fluid between a pressurized fluid source, the hydraulic actuator, and a fluid return reservoir, and a bypass fluid line providing fluid communication between the hydraulic actuator and the fluid return reservoir independent of the electrohydraulic servo valve.