Actuator Controller for Jet Engine Variable Stator Vanes
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Solution Overview
Problem
Conventional actuator control devices for synchronous links in jet engine components, such as variable stator vanes, experience force fighting due to imbalances in turning forces applied by first and second actuators, leading to inaccurate control of the angle of rotation.
Innovation Solution
An actuator control device utilizing two servo valves to independently control the first and second pistons connected to a coaxial synchronous link, with displacement sensors and force sensors, and a control unit that corrects the target position command value for the second piston based on force imbalances, ensuring precise feedback control to match the position of both pistons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-servo valve active-standby configuration is used to control both hydraulic cylinders, then device complexity is reduced, but force fighting occurs due to imbalances in turning forces applied by first and second actuators
Solution Approach 1:
The patent divides the control system into two independent servo valves (first servo valve for head chambers, second servo valve for rod chambers) instead of using a single servo valve. This segmentation allows independent control of hydraulic flow to each chamber, eliminating force fighting while maintaining reasonable system complexity.
Solution Approach 2:
The patent introduces force sensors to detect actual forces generated by each actuator and uses this feedback information to dynamically adjust control parameters. The control unit modifies servo valve commands based on detected force imbalances, ensuring synchronized operation without excessive force fighting.
2Reliability
If independent control of first and second actuators is implemented using two servo valves, then force fighting is reduced, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it controls both servo valves, processes feedback from displacement sensors and force sensors, calculates force imbalances, and generates corrected control commands. This multi-functionality consolidates control logic into a single unit, offsetting the added complexity of having two servo valves.
Solution Approach 2:
The patent implements comprehensive feedback using displacement sensors to monitor piston positions and force sensors to detect actual actuator forces. This feedback loop enables the control unit to detect and correct force imbalances in real-time, ensuring accurate control while the feedback mechanisms provide necessary information for intelligent control decisions.
3Reliability
If force sensors are added to measure forces generated in first and second actuators, then force fighting is eliminated through correction, but device complexity and cost increase
Solution Approach 1:
Force sensors provide critical feedback information about actual forces generated by each actuator. The control unit uses this feedback to detect force imbalances and dynamically correct control commands, ensuring synchronized operation. This feedback mechanism transforms the added complexity into intelligent adaptive control that eliminates force fighting.
Solution Approach 2:
The patent replaces purely mechanical force balancing mechanisms with an electro-mechanical control system. Instead of using complex mechanical linkages or spring-based force balancing, the system uses electronic sensors and control algorithms to detect and correct force imbalances, achieving more precise control with cleaner design.
Data Source
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Figure 3(a)~3(b)
AI summary
An actuator control device detects a displacement of a piston (7) in a first actuator (5), controls the first actuator (5) by feedback control, measures both of forces generated in first and second actuators (5, 4), corrects a target position command value for a piston (6) in the second actuator (4) in accordance with an amount of imbalance between the forces, and controls the second actuator (4) in accordance with the difference between the corrected command value and a feedback value of a displacement position of the second piston (6).