Three-Way Transfer Valve for Backup Electrohydraulic Actuator Control
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Solution Overview
Problem
Existing hydraulic control systems for end effectors in aircraft actuators require two full-sized electrohydraulic servo valves (EHSVs) for normal and backup operations, which increases weight, envelope, and leakage.
Innovation Solution
A system utilizing two smaller parallel EHSVs and a transfer valve that can switch between normal and backup modes by disconnecting a non-operational EHSV, allowing the functional EHSV to continue operating the actuator at reduced power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two full-sized EHSVs are used for normal and backup operations, then reliability is improved, but weight increases
Solution Approach 1:
The patent merges the functionality of two full-sized EHSVs into a single EHSV by combining their control ports. The transferred EHSV receives hydraulic fluid from both normal and backup EHSV lines simultaneously, allowing one valve to perform the work of two while maintaining backup capability through the transfer valve mechanism.
Solution Approach 2:
The transfer valve enables a single EHSV to serve multiple functions: it can operate as the primary control valve during normal operation, switch to backup mode when the primary fails, and simultaneously receive input from both normal and backup lines. This multi-functionality eliminates the need for separate dedicated normal and backup EHSVs.
2Reliability
If two full-sized EHSVs are used for normal and backup operations, then reliability is improved, but envelope increases
Solution Approach 1:
The patent merges the functionality of two full-sized EHSVs into a single EHSV by combining their control ports. The transferred EHSV receives hydraulic fluid from both normal and backup EHSV lines simultaneously, allowing one valve to perform the work of two while maintaining backup capability through the transfer valve mechanism.
Solution Approach 2:
The transfer valve enables a single EHSV to serve multiple functions: it can operate as the primary control valve during normal operation, switch to backup mode when the primary fails, and simultaneously receive input from both normal and backup lines. This multi-functionality eliminates the need for separate dedicated normal and backup EHSVs.
3Reliability
If two full-sized EHSVs are used for normal and backup operations, then reliability is improved, but leakage increases
Solution Approach 1:
The patent extracts and eliminates the redundant backup EHSV component from the system. By using a single EHSV with transfer valve capability instead of two separate EHSVs, the system removes the additional seals, spools, and hydraulic connections that would otherwise be present in a dual EHSV configuration, thereby reducing potential leakage paths.
Solution Approach 2:
The patent merges the functionality of two full-sized EHSVs into a single EHSV by combining their control ports. The transferred EHSV receives hydraulic fluid from both normal and backup EHSV lines simultaneously, allowing one valve to perform the work of two while maintaining backup capability through the transfer valve mechanism.
4Reliability
If a transfer valve and transfer EHSV are added for backup switching, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the transfer valve and transfer EHSV functions into a single integrated transfer valve mechanism. The transfer valve directly switches hydraulic connections between normal and backup lines without requiring a separate transfer EHSV, simplifying the overall system architecture while maintaining backup capability.
Solution Approach 2:
The transfer valve enables a single EHSV to serve multiple functions: it can operate as the primary control valve during normal operation, switch to backup mode when the primary fails, and simultaneously receive input from both normal and backup lines. This multi-functionality eliminates the need for separate dedicated normal and backup EHSVs.
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 reduces actuator weight, envelope, and leakage by eliminating the need for dual EHSVs and a transfer EHSV, while ensuring continued operation in case of EHSV failure.
Implementation Method 1
The first EHSV is operatively connected to pressurize one of the first actuator extend line or the first actuator retract line. A second EHSV is configured to be in fluid communication with the pressure supply and with the pressure return. The second EHSV includes a second actuator extend line and a second actuator retract line and is operatively connected to pressurize one of the second actuator extend line or the second actuator retract line.
Implementation Method 2
The transfer valve has the three following states. A first state connects both of the first EHSV and the second EHSV in fluid communication with the extend chamber and with the retract chamber for normal operation of the actuator with combined power from both the first EHSV and the second EHSV.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method includes using two parallel electrohydraulic servo valves EHSVs (102, 112) with a single transfer valve (118) to move an actuator (120) during a normal operation mode. The method includes upon failure of one of the EHSVs, using the single transfer valve to disconnect a non-operational one of the EHSVs and continuing to move the actuator with a functional one of the EHSVs in a backup mode.