Electrohydraulic Poppet Valve Null Position for Fail-Fixed Control
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Solution Overview
Problem
Existing systems for maintaining the last commanded position of devices controlled by electrohydraulic poppet valves during power interruptions are cumbersome, adding weight, complexity, and cost, particularly in environments like fuel metering valves and compressor inlet guide vanes.
Innovation Solution
An electrohydraulic poppet valve device control system that includes an actuator and poppet valves, which moves to a null position upon power loss, utilizing a torque motor and spring forces to maintain the last commanded position without the need for additional motors or complex feedback systems, thus providing back-up position control without increasing size, weight, or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stepper motor is used to maintain the last commanded position of a fuel metering valve during power interruption, then the device can remain in its last commanded position (fail-fixed functionality), but the electrical power consumption increases and the system weight increases due to additional motors and summing gearbox
Solution Approach 1:
The patent combines the fail-fixed functionality with the primary position control actuator by designing the actuator to automatically return to a predetermined position (null position) upon power loss. This eliminates the need for separate backup motors or summing gearboxes, as the same actuator serves both primary control and fail-safe functions. The fluid communication system integrates multiple functions into a unified structure.
Solution Approach 2:
The actuator is designed with multi-functionality, serving both as the primary position control mechanism and as the fail-fixed backup system. The null position mechanism provides automatic position recovery during power interruptions, while the same actuator performs normal operational control when powered. This universal design eliminates redundant components.
2Reliability
If a second stepper motor and summing gearbox are added for electrical redundancy, then the system reliability improves, but the device complexity and weight increase
Solution Approach 1:
The patent merges the redundancy function into the primary actuator system. The actuator's design inherently provides fail-fixed functionality through its null position mechanism, eliminating the need for separate redundant motors or complex summing gearbox assemblies. The fluid communication network integrates multiple control functions into a unified system.
Solution Approach 2:
The actuator serves multiple functions simultaneously: primary position control, fail-fixed backup, and automatic position recovery. This multi-functional design provides electrical redundancy without requiring separate backup systems, thereby reducing overall device complexity while maintaining reliability.
3Reliability
If a lockout valve activated by solenoid is used for compressor inlet guide vanes to maintain last commanded position, then the fail-fixed functionality is achieved, but the controller weight and complexity increase
Solution Approach 1:
The patent combines the lockout valve functionality with the primary actuator system. The actuator's null position mechanism provides automatic position maintenance during power interruptions, eliminating the need for separate solenoid-activated lockout valves. The fluid communication system integrates positioning and locking functions into a unified structure.
Solution Approach 2:
The actuator is designed with multi-functionality, serving as both the primary position control mechanism and the fail-fixed positioning system. The null position feature provides automatic position maintenance during power loss, while the same actuator performs normal operational control, eliminating redundant locking components and reducing controller weight.
4Reliability
If a stepper motor is used to drive metering valves in contaminated fuel environments, then the device can maintain position, but the force output is relatively low which limits operability in contaminated environments
Solution Approach 1:
The patent employs a hydraulic actuator system instead of a stepper motor to drive the metering valve. The hydraulic system provides significantly higher force output compared to stepper motors, enabling reliable operation in contaminated fuel environments where high force is required to overcome friction and potential sticking. The fluid communication system delivers precise position control with high force capability.
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
Effectively maintains the last commanded position of devices during power interruptions, reducing complexity and weight while ensuring reliable back-up position control, adaptable for various applications without significant additional resources.
Implementation Method 1
utilizing a torque motor and spring forces to maintain the last commanded position
Implementation Method 2
An electrohydraulic poppet valve device control system includes a main body, an extend poppet valve, a retract poppet valve, and an actuator
Data Source
AI summary
An electrohydraulic poppet valve device control system includes a main body, an extend poppet valve, a retract valve body, a retract poppet valve, and an actuator. The actuator is movable to an extend position, a retract position, and a null position, and moves to, or remains in, the null position when electrical power is not supplied to the actuator. In the extend position, the extend poppet valve is in its open position and the retract poppet valve is in its closed position. In the retract position, the extend poppet valve is in its closed position and the retract poppet valve is in its open position. In the null position, the extend poppet valve is in its closed position and the retract poppet valve is in its closed position.