Mechanical Fuel Servo Position Feedback for Closed-Loop Control
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Solution Overview
Problem
Mechanical fuel servos in aviation fuel injection systems operate open-loop without providing direct feedback of throttle valve and mixture valve positions, limiting control over engine performance and complicating troubleshooting and accident reconstruction.
Innovation Solution
Equipping mechanical fuel servos with position sensors on the throttle and mixture shafts to provide feedback to a pilot and avionics system, enabling closed-loop control and recording sensor signals for troubleshooting and health monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If mechanical fuel servos operate open-loop without position feedback, then device complexity is reduced, but control precision and reliability deteriorate
Solution Approach 1:
The patent applies feedback by installing position sensors (throttle position sensor and mixture valve position sensor) that continuously monitor the angular positions of the throttle shaft and mixture valve shaft, respectively. These sensors provide real-time feedback signals to the electronic controller, enabling the system to adjust valve positions based on actual positions rather than relying solely on pilot input, thereby improving control reliability while maintaining manageable complexity through automated closed-loop control
2Measurement precision
If position sensors are added to provide feedback, then control precision improves, but device complexity increases
Solution Approach 1:
The patent replaces manual mechanical measurement and pilot estimation with electronic position sensors that provide precise angular position measurements. The electronic controller processes sensor signals to determine exact valve positions, substituting mechanical/pilot-based control with electronic sensing and control, thereby achieving high measurement precision while managing complexity through integration of sensor and controller functions
3Reliability
If closed-loop control is implemented, then operational reliability improves, but ease of operation decreases
Solution Approach 1:
The patent applies self-service by enabling the fuel servo system to automatically adjust valve positions based on feedback from position sensors. The electronic controller continuously monitors actual valve positions and makes corrections without requiring constant pilot intervention, allowing the system to self-regulate and maintain optimal operation, thereby improving reliability while reducing the operational burden on the pilot
Data Source
AI summary
A mechanical fuel servo includes a servo body that defines an air conduit and a fuel path. The fuel servo further includes a throttle valve assembly coupled to the servo body. The throttle valve assembly includes a throttle shaft constructed and arranged to rotate responsive to control input to control airflow through the air conduit, and a throttle position sensor constructed and arranged to provide a first set of sensor signals that indicates an angular position of the throttle shaft. The fuel servo still further includes a fuel delivery assembly coupled to the servo body. The fuel delivery assembly includes a mixture valve shaft constructed and arranged to rotate responsive to other control input to control fuel flow through the fuel path, and a mixture valve position sensor constructed and arranged to provide a second set of sensor signals that indicates an angular position of the mixture valve shaft.