Failsafe Valve for Rotary Actuators With Adjustable Neutral Position
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Solution Overview
Problem
Existing hydraulic rotary actuators for aircraft control surfaces have a fixed null position and limited angular motion, making them unsuitable for applications requiring continuous revolutions and adjustable failsafe positioning.
Innovation Solution
A failsafe valve mechanism is integrated with a hydraulic rotary motor and mechanically connected to the control surface, allowing the control surface to be hydraulically powered to a neutral failsafe position in failure events, with a metering spool adjusting control line connections to achieve adjustable failsafe positioning and continuous motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed HITW port is provided in the hydraulic rotary actuator, then the null position during failsafe mode is determined, but the location of the port is fixed and cannot be changed, making the actuator suitable only for specific applications with designed null position
Solution Approach 1:
The patent replaces the fixed HITW port with a dynamic valve mechanism that can adjust the null position. The valve includes a spool that can be positioned at different locations along its travel, allowing the null position to be dynamically adjusted rather than fixed during manufacturing. This enables the same actuator to be adapted to different applications with different required null positions.
Solution Approach 2:
The patent changes the parameter of null position from a fixed geometric parameter (determined by port location) to a controllable parameter (determined by valve spool position). By using hydraulic pressure to position the spool, the null position can be adjusted without physical modifications to the actuator structure, enabling adaptability across different applications.
2Reliability
If a HITW port is provided in the stator to provide return pressure, then the rotor rotates toward null position in failsafe mode, but the range of rotary motion is limited to an angle less than 360 degrees, preventing continuous revolutions
Solution Approach 1:
The patent segments the hydraulic system into multiple circuits: a primary circuit for normal operation allowing continuous rotation, and a secondary failsafe circuit that activates only when needed. The failsafe valve remains stationary while controlling hydraulic flow to the motor, eliminating the need for a fixed port in the rotating stator that would limit rotation range.
Solution Approach 2:
The patent introduces a failsafe valve as an intermediary component between the hydraulic power source and the motor. This valve mediates the hydraulic flow control, allowing the motor to rotate continuously through full 360 degrees while the valve itself remains stationary and provides failsafe positioning capability without limiting the motor's rotational range.
3Adaptability or versatility
If a failsafe valve is integrated with hydraulic rotary motor and mechanically connected to control surface, then adjustable failsafe positioning and continuous revolutions are enabled, but device complexity increases
Solution Approach 1:
The patent merges the failsafe valve with the hydraulic rotary motor by integrating the valve housing with the motor housing and using a common shaft connection. The failsafe valve spool is mechanically connected to the control surface through the same shaft that drives the motor, combining multiple functions into a single integrated assembly rather than separate components.
Solution Approach 2:
The integrated failsafe valve mechanism serves multiple functions: it provides normal hydraulic flow control during operation, enables failsafe positioning when pressure is lost, allows adjustable null position through spool positioning, and permits continuous rotation of the motor. This multi-functionality reduces the need for separate components and justifies the integration complexity.
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
Enables adjustable failsafe positioning and continuous revolutions of the control surface, enhancing the adaptability and functionality of hydraulic rotary actuators in aircraft control systems.
Implementation Method 1
A failsafe valve mechanism is integrated with a hydraulic rotary motor and mechanically connected to the control surface, allowing the control surface to be hydraulically powered to a neutral failsafe position in failure events, with a metering spool adjusting control line connections
Data Source
AI summary
A failsafe vale provides “Hole-In-The-Wall” failsafe functionality for thin-wing aircraft control surface actuation systems having a geared rotary actuator powered by a hydraulic rotary motor. The failsafe valve is associated with the hydraulic rotary motor and mechanically connected to the control surface, and enables the flight control surface to return to an aerodynamically neutral failsafe position if electrical control and/or hydraulic pressure is lost. When the failsafe valve receives a normal command pressure from the hydraulic system, the valve is inactive and the actuation system operates normally. However, if there is a loss of electrical command capacity to control hydraulic valves and/or a loss of hydraulic pressure, the failsafe valve is activated and connects one of the motor hydraulic control lines to the case return line for the motor if the control surface is away from its failsafe position. Consequently, the control surface will be hydraulically powered or aerodynamically ratcheted to its failsafe position in the failure event.