Flight Control Actuator Drive Redundancy via Irreversible Gears
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Solution Overview
Problem
Traditional flight control systems with redundant motor drives face issues due to back-driving when one motor fails, leading to system non-operationality, and existing solutions like electromechanical braking add weight and complexity.
Innovation Solution
A speed summing device with a planetary gear assembly, including input ring gears, planet gears, and a planet carrier, where the planet gears are free to rotate about their axes, and irreversible gears prevent back-driving, allowing operation with one or two motors without system failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed summing device combines rotations of two motors to provide redundancy, then reliability is improved, but the device becomes non-operational when one motor fails due to back-driving
Solution Approach 1:
A one-way clutch mechanism is introduced as an intermediary between the motor shafts and the speed summing device. This mediator allows the speed summing device to receive rotational input from operational motors while preventing it from back-driving failed motors, thus maintaining system operation in redundant mode
2Reliability
If electromechanical braking arrangements are used to prevent back-driving, then reliability is improved, but weight and device complexity increase
Solution Approach 1:
The complex electromechanical braking arrangements are extracted and replaced with a simpler one-way clutch mechanism. This extraction removes unnecessary complexity while retaining the essential function of preventing back-driving, thereby reducing weight and simplifying the overall system design
3Reliability
If two separate motors and motor drives are used to power the actuator, then reliability is improved through redundancy, but device complexity increases
Solution Approach 1:
The speed summing device merges the rotational outputs of two separate motors into a single unified output shaft that drives the actuator. This combining approach maintains redundancy benefits while consolidating the mechanical transmission path, thereby reducing overall system complexity compared to having two independent transmission systems
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 redundancy and prevents back-driving, ensuring continuous operation of the flight control actuator drive even if one motor fails, without adding excessive weight or complexity.
Implementation Method 1
a planetary gear assembly formed of the two ring gears, the pairs of planet gears and the planet carrier
Implementation Method 2
the planet carrier being driveably connected to the planet gears such that movement of the planet gears around the central axis causes the planet carrier to rotate
Implementation Method 3
a first motor driveably connected to the first ring gear via a first irreversible gear so that the first ring gear can transmit power in one direction only
Data Source
Figure 1~2
Figure 3~4
AI summary
A flight control actuator drive (100) comprises a first motor (10) for providing a first rotational input, a second motor (12) for providing a second rotational input and a speed summing device (20) for combining the first and second rotational inputs into a rotational output for controlling an actuator. The speed summing device (20) comprises first and second input gears (22, 24) to which the first and second motors (10, 12) are connected via first and second irreversible gears (14, 16) so that the first and second input gears (22, 24) can each transmit power in one direction only. The speed summing device (20) may be a planetary gear assembly.