Spoiler Actuator Cam Locking to Prevent Torque Feedback Damage
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Solution Overview
Problem
Existing electromechanical actuators for aircraft components, such as spoilers, suffer from weight considerations due to the inclusion of torque limiters and anti-extension devices that add unnecessary bulk, and there is a risk of damage from excessive torque feedback during flight.
Innovation Solution
An electromechanical actuator design that integrates a cam mechanism within the anti-extension device, allowing automatic disabling of the anti-extension function when the output rod reaches a predetermined position, eliminating the need for a torque limiter and enabling smoother operation by controlling the engagement of the pawl with the ratchet wheel through a solenoid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque limiter and anti-extension device are included in the actuator design, then protection against excessive torque feedback is improved, but the weight of the actuator increases
Solution Approach 1:
The patent removes the torque limiter from the actuator design, extracting this component entirely. The anti-extension device is modified to function without the torque limiter, using a cam mechanism that allows controlled extension while maintaining protection against excessive torque feedback through the pawl-ratchet engagement system alone.
Solution Approach 2:
The patent combines the anti-extension function with the extension control function into a single integrated mechanism. The cam mechanism works in conjunction with the pawl-ratchet system to provide both anti-extension protection and controlled extension capability, eliminating the need for separate torque limiting components.
2Reliability
If an anti-extension device is activated to prevent rotation of the screw shaft, then protection against output rod extension is improved, but the device complexity increases
Solution Approach 1:
The cam mechanism is designed to be automatically actuated by the position of the output rod itself. As the output rod extends or retracts, it directly controls the cam's position, which in turn controls the pawl's engagement with the ratchet wheel. This self-actuating system eliminates the need for external sensors, actuators, or control systems to manage the anti-extension function.
Solution Approach 2:
The patent introduces dynamic control of the anti-extension function through the cam mechanism. The pawl's engagement with the ratchet wheel is not fixed but dynamically adjusted based on the output rod's position. The cam allows the pawl to disengage when extension is desired and re-engage when anti-extension protection is needed, providing adaptive protection rather than static locking.
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 new design reduces weight by eliminating the torque limiter and prevents damage by automatically disabling the anti-extension mechanism at specific positions, ensuring reliable operation and reducing mechanical stress on the motor.
Implementation Method 1
controlling the engagement of the pawl with the ratchet wheel through a solenoid
Implementation Method 2
integrates a cam mechanism within the anti-extension device, allowing automatic disabling of the anti-extension function when the output rod reaches a predetermined position
Implementation Method 3
a pivotable rod comprising a pawl; the pivotable rod being pivotable between a first position in which the pawl engages with the ratchet wheel
Data Source
AI summary
An electromechanical actuator comprises: a motor; a gearbox; an anti-extension device mounted between the motor and the gearbox. The motor and anti-extension device are mounted on a housing of the actuator. The actuator further comprises a screw shaft; a nut mounted on the screw shaft; an output rod connected to the nut, the output rod having a linear range of motion defined between full extension of the output rod at a first end point (A) and full retraction of the output rod at a second end point (C). The screw shaft, nut, and output rod are located in a cavity of the housing. The output rod and nut are held against rotation relative to the housing, such that rotation of the screw shaft drives the output rod to move linearly within the housing.