Fluid-Damped Fuse Actuator for Trim Linkage Jam Protection
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Solution Overview
Problem
Existing actuator systems in aircraft, particularly trim actuators, face challenges in preventing jamming, which can lead to sudden and excessive movement of flight control linkages, potentially causing damage due to the high force required to break a fusible pin and the need for human intervention in some torque limiter systems, and the weight and size issues with electromagnetic solutions.
Innovation Solution
An actuator with a fusible connection and a fluid damper device that limits the speed of the output lever's movement after the fusible connection breaks, using a leaktight chamber filled with fluid and vanes to generate damping forces proportional to the travel speed, thereby reducing the risk of damage and eliminating the need for human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fusible pin is used to constrain the output arrangement and output lever to move together, then the actuator maintains mechanical torque transmission, but the pin may break suddenly when torque exceeds threshold causing rapid movement and potential damage
Solution Approach 1:
The patent introduces a fluid damper device that is pre-positioned between the output arrangement and output lever. When the fusible pin breaks, the fluid damper immediately engages to dampen the sudden movement, preventing damage to the flight control linkage. This beforehand cushioning mechanism ensures that the harmful effects of pin failure are mitigated before they can cause damage.
Solution Approach 2:
The fluid damper acts as an intermediary element between the fusible pin connection and the flight control linkage. It mediates the transition when the pin breaks by providing controlled resistance to movement, allowing the output lever to move relative to the output arrangement in a controlled manner rather than suddenly, thus protecting the system from damage.
2Reliability
If a retractable coupling device with locking means and compression means is used, then torque limitation is achieved, but human intervention is required to reset the device after activation
Solution Approach 1:
The fusible pin system with fluid damper is designed to be self-activating and self-resetting. When excessive torque occurs, the fusible pin automatically breaks and the fluid damper automatically engages to limit movement. After the incident, the system can be reset by simply replacing the pin, without requiring manual intervention to reset compression means or locking mechanisms, thus eliminating the need for complex resetting procedures.
3Extent of automation
If an electromagnetic system with electric coil is used for torque limitation, then automated control is achieved, but weight and size increase significantly
Solution Approach 1:
The patent replaces complex electromagnetic torque control systems with a simpler mechanical-fusible system combined with fluid damping. Instead of using electric coils and electromagnetic actuators to actively control torque, the system uses a passive fusible pin that breaks at a predetermined torque threshold, combined with a fluid damper that passively limits movement speed. This substitution dramatically reduces weight and complexity while maintaining effective torque limitation functionality.
Solution Approach 2:
The fusible pin is designed as a disposable, low-cost component that is intentionally designed to fail at a specific torque threshold. Rather than using expensive, heavy electromagnetic systems that require active control and monitoring, the patent employs a simple, inexpensive pin that breaks when needed, with the more expensive fluid damper serving as a reusable protective element. This approach optimizes the weight-cost-performance balance.
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 fluid damper device significantly reduces the speed of the output lever's movement by a factor of three compared to prior art, preventing damage and ensuring smooth operation without the need for human intervention, while maintaining a simple, lightweight, and cost-effective design.
Implementation Method 1
a fluid damper device to act following rupture of said fusible connection to damp movement of said output lever relative to the output arrangement in rotation about said axis of rotation
Data Source
AI summary
An actuator provided with a motor for moving an output arrangement, the actuator including both an output lever and a fusible connection that acts up to a mechanical torque threshold to constrain the output arrangement and the output lever to move together in rotation about an axis of rotation. The actuator also includes a fluid damper device housed between the output lever and the output arrangement to act, following rupture of the fusible connection, to damp movement of the output lever relative to the output arrangement in rotation about the axis of rotation.