Multi-Head Hydraulic Actuator Using Solenoid Pressure Selection
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Solution Overview
Problem
Aircraft hydraulic actuators often require complex electrohydraulic servo valve (EHSV) systems for modulated control, which can be heavy, space-intensive, and prone to failures, necessitating a simpler and more reliable actuation solution.
Innovation Solution
A two-position hydraulic actuator system utilizing a combination of three 3-way solenoids and a biasing mechanism to selectively connect high or low pressure fluid sources to the piston, allowing for redundant control and reduced weight and space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrohydraulic servo valve (EHSV) systems are used for modulated control, then control precision is improved, but device complexity and weight increase
Solution Approach 1:
The piston is divided into multiple heads (first piston head and second piston head) that can be independently controlled by separate solenoid valves. This segmentation allows simplified two-position control for each piston head while achieving overall modulated control functionality, reducing the need for complex EHSV systems.
Solution Approach 2:
Multiple solenoid valves are combined to control multiple piston heads within a single actuator housing. The first solenoid valve controls the first piston head and the second solenoid valve controls the second piston head, merging control functions into one integrated system that avoids the complexity of traditional EHSV while maintaining control precision.
2Measurement precision
If electrohydraulic servo valve (EHSV) systems are used for modulated control, then control precision is improved, but weight increases
Solution Approach 1:
The actuator is segmented into multiple independent piston-head-solenoid combinations, each using lightweight solenoid valves instead of heavy EHSV components. This segmentation allows the use of simpler, lighter valves while maintaining control precision through coordinated operation of multiple piston heads.
Solution Approach 2:
The complex EHSV system is extracted and replaced with simpler solenoid valve mechanisms. By removing the heavy EHSV components and using multiple lightweight solenoid valves to control segmented piston heads, the overall actuator weight is reduced while control precision is maintained through the multi-head configuration.
3Measurement precision
If electrohydraulic servo valve (EHSV) systems are used for modulated control, then control precision is improved, but reliability decreases
Solution Approach 1:
The control system is segmented into multiple independent solenoid valve-piston head channels. If one solenoid valve or piston head fails, the other channels can continue to operate, providing inherent redundancy that improves reliability while maintaining control precision through the remaining functional channels.
Solution Approach 2:
The multi-head piston configuration provides beforehand cushioning against failure by having redundant control channels. The system is designed with multiple independent solenoid valves and piston heads so that failure of one component is compensated by the others, ensuring continuous operation and maintaining control precision even under degraded conditions.
4Device complexity
If simpler actuation systems are used, then device complexity and weight are reduced, but control precision deteriorates
Solution Approach 1:
Multiple simple solenoid valve-piston head combinations are merged into a single coordinated system. The first solenoid valve controls the first piston head and the second solenoid valve controls the second piston head, with both working together to achieve modulated control precision equivalent to or exceeding traditional EHSV systems, while maintaining simplicity in each individual control channel.
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
The solution provides a lightweight, compact, and reliable actuation system with reduced internal leakage and increased mean time between failures, suitable for aircraft applications where weight and space are critical, while maintaining control over aircraft components like fan vanes and exhaust nozzles.
Implementation Method 1
A two-position hydraulic actuator system utilizing a combination of three 3-way solenoids and a biasing mechanism to selectively connect high or low pressure fluid sources to the piston
Implementation Method 2
A two-position hydraulic actuator system utilizing a combination of three 3-way solenoids and a biasing mechanism to selectively connect high or low pressure fluid sources to the piston
Data Source
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AI summary
A hydraulic actuator system of an aircraft includes a hydraulic actuator (108) having a housing with a piston having a piston shaft with a piston head (114) attached thereto and arranged within the housing. The piston head (114) divides in internal volume of the housing into an extend cavity and a retract cavity and the extend cavity is configured to be connected to low pressure fluid source. The system also includes a pressure selector unit (160) fluidly connected to the retract cavity and configured to be connected to the low pressure fluid source and to a high pressure fluid source. The unit include three solenoids with the first and second connected in parallel to the fluid sources and the third solenoid (106) having a third solenoid first input connected to the first solenoid output, a third solenoid second input connected to the second solenoid output, and a third solenoid output connected to the retract cavity.