Spoiler Actuator Valve Control with Fail-Safe Neutral Stop
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Solution Overview
Problem
In aircraft systems, there is a challenge in preventing spoilers from interfering with wing flaps during electrical or hydraulic failures, particularly when in negative stroke or droop mode, leading to potential interference and movement issues.
Innovation Solution
A hydraulic actuator control arrangement with a moveable stop and solenoid valve system that re-centers the spoiler to its neutral position in case of electrical failure, using an electrohydraulic servovalve and anti-extension valve to manage fluid flow and prevent unwanted extension or interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spoiler is extended and electrical power is lost, then the EHSV biases to retract the spoiler, but the spoiler may still interfere with wing flaps due to aerodynamic loads and pressure differentials
Solution Approach 1:
A movable stop is introduced as an intermediary mechanical element between the piston rod and the housing. This stop actively intervenes in the force balance by providing a mechanical constraint that prevents the piston rod from moving into positions that would cause spoiler-flap interference, even when hydraulic pressure differentials or aerodynamic loads are present.
Solution Approach 2:
The movable stop is positioned and controlled to preemptively counteract harmful forces before they can cause interference. By monitoring system state and adjusting the stop position, the invention applies preliminary mechanical opposition to aerodynamic loads and pressure differentials that would otherwise push the spoiler into interfering positions during electrical failure conditions.
2Reliability
If the EHSV is biased to retract the spoiler during electrical failure, then the spoiler returns to neutral position, but excessive drag is generated during the transition
Solution Approach 1:
The stop is designed to be movable rather than fixed, allowing it to dynamically adjust its position based on operational conditions. During normal operation, the stop permits full spoiler range of motion. During electrical failure, the stop moves to a position that guides controlled retraction, optimizing the balance between reliable return-to-neutral and minimizing drag during the transition phase.
3Object-affected harmful factors
If a mechanical stop is used to prevent piston rod movement, then the spoiler position is limited, but the system loses adaptability to different operational modes including negative stroke
Solution Approach 1:
The movable stop replaces fixed mechanical limits with a dynamically adjustable constraint. The stop can be repositioned along the piston rod axis to accommodate different operational requirements: in normal mode it allows full extension for positive stroke operation, while in electrical failure mode it positions itself to enable controlled retraction to neutral, and it can be adjusted to permit negative stroke operations when required.
Solution Approach 2:
The stop mechanism is divided into separable functional components: the stop element itself, the actuation mechanism for moving the stop, and the sensing/control system. This segmentation allows the stop to be independently controlled and repositioned to serve different operational modes without compromising the overall actuator functionality or requiring complete system redesign.
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
Ensures safe re-centering of the spoiler to its neutral position even during electrical failure, preventing interference with wing flaps and maintaining system functionality.
Implementation Method 1
a solenoid valve (140) arranged between a pressure source (HP) and the actuator (100), the solenoid valve (140) switchable between a first mode and a second mode in response to an electric control signal
Implementation Method 2
a hydraulic actuator (100) having a housing (200) and a piston rod (300) axially moveable within the housing (200) between a neutral position, a retracted position and an extended position in response to application of pressure to the piston rod (300)
Data Source
AI summary
An actuator control arrangement includes a hydraulic actuator having a housing and a piston rod axially moveable within the housing, a stop disposed within the housing to limit the extent of movement of the piston rod into the housing, and a solenoid valve arranged between a pressure source and the actuator. The solenoid valve is switchable between a first mode and a second mode in response to an electric control signal, wherein, in the first mode, the solenoid valve creates a fluid flow path from the pressure source to the actuator so as to locate the stop in its neutral position and in the second mode, the solenoid valve creates a fluid flow path to release pressure from the actuator to permit the stop to move to its retracted position. In the event of electrical failure, the stop will set the actuator to its neutral position.