Actuator Damping via Laminated Fluid Flow
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Solution Overview
Problem
Existing mechanical and electrohydraulic actuators face challenges in providing reliable and speed-dependent damping for aircraft landing gear, with issues such as wear, insufficient resistance, and complexity in emergency operation.
Innovation Solution
A mechanically actuated actuator with a closed hydraulic circuit that uses laminated fluid flow to create damping proportional to the square of the rod's movement speed, allowing for reliable and passive damping and emergency operation without the need for a reversible pump, utilizing a screw-nut connection and accumulator system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic damping is organized by rolling fluid expelled from a chamber, then damping force proportional to the square of rod speed is achieved, but the actuator requires a reversible pump for emergency operation
Solution Approach 1:
The patent divides the actuator into two independent operation modes: normal operation using a non-reversible pump for fluid transfer, and emergency operation allowing free rod movement with hydraulic damping. This segmentation eliminates the need for pump reversibility while maintaining emergency capability.
Solution Approach 2:
During emergency operation, the system uses itself for damping by allowing fluid to be expelled from one chamber and roll on the outlet, creating passive hydraulic damping without requiring active pump control or reversibility.
2Reliability
If mechanical damping is organized by friction or electromagnetic resistance, then damping is provided, but wear and reliability problems occur
Solution Approach 1:
The patent uses hydraulic damping by organizing fluid to roll on its outlet during emergency rod movement, creating a reliable damping force proportional to the square of rod speed without mechanical contact, thus eliminating wear problems associated with friction-based damping.
3Force
If frictional resistance is used for damping, then damping is provided, but the resistance is essentially independent of rod movement speed
Solution Approach 1:
The patent implements hydraulic damping where fluid is expelled from a chamber and rolls on the outlet during rod movement, generating a damping force that is naturally proportional to the square of the rod's movement speed, providing speed-dependent resistance without friction.
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 reliable, simple, and passive damping and braking, reducing wear and energy dissipation issues, while enabling efficient emergency operation and monitoring of the actuator's performance through hydraulic regulation.
Implementation Method 1
fluid is expelled from one of the chambers to return to the other via the pipe, being laminated, at least for one direction of movement, which contributes to damping any tendency to vibrations of the load attached to the actuator
Implementation Method 2
during emergency operation during which the rod is left free to slide while being driven by the load coupled to the actuator, the rolling of the fluid thus organized makes it possible to exert a slowing down force proportional to the square of the rod movement speed
Data Source
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AI summary
The invention relates to an actuator comprising a body (1;101) in which a rod (2;102) is mounted to slide, the actuator comprising a screw (8;108) extending inside the rod to cooperate with a nut (7;107) fixed to the rod, the screw being driven in rotation by a motor (23;123). According to the invention, the rod is associated with a piston (5;125) which slides in a cavity (C) of the body to define two chambers (C1,C2), these being filled with hydraulic fluid and connected by fluid transfer means equipped with at least one regulating element (36,37;136,137) adapted to compress fluid expelled from one of the chambers, at least for one direction of rod movement.