Spoiler Actuator Check Valve Linkage for Flap Interference Prevention
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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, especially when the spoiler is in a droop mode, as they can extend and cause drag or interfere with flap movement due to their own weight or pressure.
Innovation Solution
A hydraulic actuator control arrangement featuring a check valve with a mechanical link that activates in response to the piston rod's negative stroke, ensuring the check valve opens to prevent interference between the spoiler and wing flap, even in failure scenarios, using a combination of an electrohydraulic servovalve and solenoid valve for fluid control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spoiler is allowed to droop (negative stroke) using a conventional valve arrangement, then the spoiler can lower for high lift maneuvers, but the spoiler may interfere with wing flap movement or extend excessively during electrical or hydraulic failures
Solution Approach 1:
A mechanical link is introduced as an intermediary between the piston rod and the valve spool. This mechanical link directly couples the piston rod position to the valve spool position, ensuring that when the piston rod reaches a predetermined retracted position during negative stroke, the valve spool is automatically actuated to close the flow path and prevent further spoiler movement, even during failures
Solution Approach 2:
The mechanical link is designed to preemptively actuate the valve spool to the closed position when the piston rod reaches a predetermined position during negative stroke. This preliminary action prevents the spoiler from extending further or interfering with wing flaps before a failure condition can occur, by establishing a mechanical constraint that overrides electrical or hydraulic control signals
2Ease of operation
If an electrohydraulic servovalve is used to control the spoiler, then precise control is achieved, but the system becomes vulnerable to electrical or hydraulic failures that can cause uncontrolled spoiler movement
Solution Approach 1:
The control system is segmented into two independent control paths: an electrical control path through the electrohydraulic servovalve for normal precise operation, and a mechanical control path through the mechanical link for failure safety. The mechanical link operates independently of the electrical system, providing a backup control mechanism that activates when the electrical or hydraulic system fails
Solution Approach 2:
The mechanical link serves as a mediator that translates piston rod position directly to valve spool position, bypassing the electrical control system. This mechanical intermediary ensures that even when electrical or hydraulic control is lost, the valve spool will be positioned to close the flow path and prevent uncontrolled spoiler movement
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 solution allows reliable operation of spoilers in droop mode, ensuring they return to a neutral position passively in case of failures, preventing interference with wing flaps and allowing manual movement without strong hydraulic forces, thus maintaining aircraft stability and operational safety.
Implementation Method 1
a mechanical link between the piston rod and the check valve, actuated in response to the piston rod passing a predetermined retracted position in a negative stroke direction, to set the check valve to the first position
Implementation Method 2
The valve is positioned between the hydraulic fluid supply and the actuator and is moveable, in response to an electric control signal, between a first position in which high pressure fluid flows from the supply into one chamber of the actuator housing
Implementation Method 3
The check valve is preferably biased to the second position by means of a spring
Implementation Method 4
high pressure fluid is provided to the actuator, from a hydraulic fluid supply in fluid communication with the interior of the actuator housing via the ports in the housing, to cause the piston rod to extend out of the housing
Data Source
AI summary
An actuator control arrangement comprising: a hydraulic actuator having a housing and a piston rod axially moveable within the housing between a neutral position, a retracted position and an extended position with respect to the housing in response to application of pressure to the piston rod; the arrangement further comprising a check valve moveable between a first position providing a flow path between a pressure source and the actuator, and a second position in which the flow path is closed off; and characterised by a mechanical link between the piston rod and the check valve, actuated in response to the piston rod passing a predetermined retracted position in a negative stroke direction, to set the check valve to the first position.