Parallel Electrohydraulic Servo Valve Backup Switching for Leak Control
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Solution Overview
Problem
Conventional systems requiring dual electrohydraulic servo valves (EHSVs) for actuator control are bulky, heavy, and prone to leakage, with a need for improved backup and control mechanisms.
Innovation Solution
A system utilizing two parallel small-sized EHSVs, each connected to a transfer valve and solenoid valve, allowing for seamless switching to a backup EHSV in case of failure, while maintaining actuator control through shared actuator lines and a controller for managing operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two full sized EHSVs are used for normal and backup operation, then system reliability is improved, but device complexity and weight increase
Solution Approach 1:
The patent divides the backup system into modular components: two smaller EHSVs instead of one large EHSV, with each valve having its own dedicated transfer valve. This segmentation allows independent failure isolation and simplifies the overall system architecture while maintaining reliability.
Solution Approach 2:
The patent uses two smaller EHSVs that each provide partial capability (50% of full capacity) but together can provide full capability. During normal operation, one EHSV provides full actuator control; during failure, the second EHSV provides reduced capability control, accepting partial performance degradation for improved system weight and complexity.
2Reliability
If two full sized EHSVs are used for normal and backup operation, then system reliability is improved, but weight increases
Solution Approach 1:
The patent segments the valve system into two smaller EHSVs with shared hydraulic lines, reducing the total weight compared to one large EHSV plus backup. Each smaller valve weighs less than a full-sized valve, and the shared lines eliminate redundant heavy piping.
Solution Approach 2:
The patent merges the hydraulic lines by having both EHSVs share common actuator extend and retract lines, as well as common pressure supply and return lines. This consolidation eliminates duplicate heavy piping and reduces overall system weight while maintaining the ability to independently control the actuator through either valve.
3Reliability
If conventional EHSV backup system is used, then reliability is improved, but leakage increases
Solution Approach 1:
The patent segments the hydraulic system into separate controlled zones with individual transfer valves for each EHSV. This segmentation isolates potential leakage sources, allowing failure containment to specific lines without affecting the entire system, thereby reducing harmful leakage effects.
Solution Approach 2:
The patent employs transfer valves with solenoid actuators that can be electrically controlled to isolate failed EHSVs from the actuator. This allows the system to abandon (disconnect) a leaking EHSV and continue operation with the remaining functional valve, effectively treating the failed component as disposable to prevent ongoing leakage problems.
4Reliability
If transfer valve and solenoid are used for switching, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent assigns a dedicated transfer valve to each EHSV, creating independent switching channels. This segmentation simplifies the control logic compared to a single complex transfer mechanism, as each transfer valve only needs to handle one EHSV's connection/disconnection independently.
Solution Approach 2:
The transfer valves are equipped with solenoid actuators that enable automatic switching based on controller commands. This self-service capability eliminates the need for manual intervention or complex mechanical switching mechanisms, reducing overall device complexity while improving switching reliability through automated failure detection and isolation.
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 configuration reduces actuator weight, envelope, and leakage, enabling continued operation at reduced power with a single EHSV in backup mode, while locking the actuator in overpressure events, thus enhancing system stability and reliability.
Implementation Method 1
two parallel electrohydraulic servo valves (EHSVs) sized at less than full capability
Implementation Method 2
The first transfer valve can include a piston configured in a first position to allow flow through the first actuator extend line and to allow flow through the first actuator retract line, and in a second position to block flow through the first actuator extend line and to block flow through the first actuator retract line
Implementation Method 3
The first solenoid valve can be operatively connected to actuate the first transfer valve. The first solenoid valve can be in fluid communication with an actuation port of the first transfer valve, and with the pressure supply and the pressure return for selectively pressurizing/depressurizing the actuation port of the first transfer valve
Implementation Method 4
An actuator includes an extend chamber in fluid communication with both of the first and second extend actuator lines, and a retract chamber in fluid communication with both of the first and second retract actuator lines for extending an end effector when the first and second EHSVs pressurize the extend chamber, and for retracting the end effector when the first and second EHSVs pressurize the retract chamber
Data Source
AI summary
A system includes a first electrohydraulic servo valve (EHSV) configured to be in fluid communication with a pressure supply and with a pressure return. The first EHSV includes a first actuator extend line and a 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. An actuator includes an extend chamber in fluid communication with both of the first and second extend actuator lines, and a retract chamber in fluid communication with both of the first and second retract actuator lines for extending an end effector when the first and second EHSVs pressurize the extend chamber, and for retracting the end effector when the first and second EHSVs pressurize the retract chamber.