Shuttle Stop Force Limiter for Aircraft Actuator Overload Protection
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Solution Overview
Problem
Aircraft flight control actuation systems face challenges in preventing damage from overloads, such as jamming or failure of actuators or drive shafts, which can lead to unintended movement of flight control surfaces, altering lift characteristics and potentially causing damage to the aircraft.
Innovation Solution
An actuator design featuring a shuttle that moves axially relative to a rotary input member, shifting from a disengaged to an engaged position to prevent further rotation during overloads, using a stop mechanism to block the rotary input member and limit force application, thereby preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a force limiting device is used to prevent damage from overload, then the reliability of the actuation system is improved, but the device complexity increases
Solution Approach 1:
The shuttle is designed to dynamically shift between a disengaged position (allowing normal operation) and an engaged position (blocking rotation during overload). This dynamic reconfiguration allows the same component to serve dual purposes: enabling free rotation during normal operation and preventing rotation during overload conditions, thereby providing protection without permanently increasing structural complexity
Solution Approach 2:
The shuttle acts as an intermediary mechanism between the rotary input member and the worm gear. It mediates the transmission of rotational force by selectively engaging or disengaging based on load conditions, providing a simple yet effective means of overload protection that avoids complex sensing and control systems
2Ease of operation
If a shuttle mechanism is used to shift from disengaged to engaged position, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The force limiting device is designed to automatically respond to overload conditions without requiring external control or intervention. The shuttle self-actuates based on the mechanical state of the system, shifting to the engaged position when overload occurs and allowing automatic stalling of the PDU, thereby simplifying operation while maintaining a mechanical structure
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 prevents further rotation of the rotary input member during overloads, protecting the actuator and aircraft components from damage by directly opposing torque without relying on friction coefficients, allowing for safe operation and easy reset.
Implementation Method 1
the shuttle is movable axially relative to the rotary input member by continued rotation of the rotary input member so that a stop on the shuttle moves from an ambush position allowing free rotation of the rotary input member to a blocking position preventing further rotation of the rotary input member
Implementation Method 2
a stop on the shuttle moves from an ambush position allowing free rotation of the rotary input member to a blocking position preventing further rotation of the rotary input member
Data Source
AI summary
Provided is an actuator characterized by the use of a shuttle that shifts in response to an overload. The shuttle is movable axially relative to a rotary input member by continued rotation of the rotary input member so that a stop on the shuttle moves from an ambush position allowing free rotation of the rotary input member to a blocking position preventing further rotation of the rotary input member. In this way, the shuttle prevents rotation of a rotary input member during an overload of a control surface.