Aircraft Engine Cowl Door Screw Actuator Without Hydraulics
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Solution Overview
Problem
Current hydraulic actuators used for opening aircraft engine cowl doors face challenges such as decreased performance at cold temperatures, mechanical lock malfunctions, hydraulic oil contamination, and oil leakage, requiring a more reliable, cost-effective, and lightweight solution.
Innovation Solution
An electro-mechanical actuator system comprising a housing, screw shaft, transmission system, nut, piston rod, and lost motion device with a compression coil spring to absorb vibrations and thermal expansion, powered by an electric motor with a torque limiter and manual operation capabilities, eliminating hydraulic components and their associated issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic actuators are used for opening cowl doors, then the actuation function is achieved, but reliability deteriorates due to oil leakage, contamination, and mechanical lock malfunction
Solution Approach 1:
The patent removes the hydraulic system entirely from the actuator design, extracting the problematic hydraulic components (oil, seals, pressure relief valves, mechanical locks) and replacing them with a purely mechanical screw-driven system. This elimination of hydraulic elements directly resolves the reliability issues caused by oil leakage and contamination while maintaining the door opening function.
Solution Approach 2:
The patent replaces the hydraulic mechanical system with a simplified mechanical system based on a screw shaft and nut mechanism. The electric motor drives the screw shaft, which translates rotational motion into linear motion of the piston rod through the nut, eliminating the need for hydraulic fluid and associated components, thereby improving reliability.
2Reliability
If hydraulic actuators are used, then actuation is achieved, but weight increases due to multiple hydraulic components
Solution Approach 1:
The patent extracts and removes all heavy hydraulic components (hydraulic oil reservoir, pumps, valves, seals, and mechanical locks) from the actuator design. The resulting lightweight actuator uses only essential mechanical elements (screw shaft, nut, piston rod, and electric motor), significantly reducing overall weight while maintaining functional simplicity and reliability.
Solution Approach 2:
The patent discards the complex hydraulic system and recovers only the essential mechanical transmission function needed for door actuation. By eliminating unnecessary hydraulic components and retaining only the critical screw-driven linear motion mechanism, the design achieves both weight reduction and simplified structure.
3Productivity
If hydraulic actuators are used, then door opening is achieved, but performance decreases at cold temperatures due to increased oil viscosity
Solution Approach 1:
The patent replaces the hydraulic system with a mechanical screw-driven system that is insensitive to temperature variations. The electric motor provides consistent torque across temperature ranges, and the screw-nut mechanism translates this torque into reliable linear motion without being affected by fluid viscosity changes, ensuring consistent performance in cold environments.
Solution Approach 2:
The patent changes the operating parameter from hydraulic fluid flow (which is highly temperature-dependent) to mechanical torque transmission through a screw mechanism. This parameter change eliminates the temperature sensitivity issue, as mechanical friction and torque characteristics remain relatively stable across a wide temperature range, maintaining actuator performance in cold conditions.
4Reliability
If hydraulic actuators are used, then actuation is achieved, but maintenance complexity increases due to multiple components requiring careful design and maintenance
Solution Approach 1:
The patent extracts and eliminates all maintenance-intensive hydraulic components (seals, pressure relief valves, mechanical locks, and hydraulic circuitry) from the actuator design. The simplified mechanical system with fewer moving parts requires minimal maintenance, improving both durability and ease of repair while maintaining reliable door opening functionality.
Solution Approach 2:
The patent discards the complex hydraulic subsystem and recovers only the essential actuation function through a simplified mechanical screw-driven system. This reduction in component count directly decreases maintenance complexity while enhancing durability, as there are fewer parts that can fail or require servicing.
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 electro-mechanical actuator system provides reliable, cost-effective, and lightweight operation of aircraft engine cowl doors, improving durability and reducing maintenance complexity by eliminating hydraulic system vulnerabilities and allowing for manual operation without electronic feedback.
Implementation Method 1
a lost motion device coupled to the piston rod and disposed within the hollow interior of the piston rod, the lost motion device comprising a compression coil spring arranged within the hollow interior of the piston rod and between an inwardly extending flange of the piston rod and the rod end, wherein the rod end is slidably mounted in the hollow piston rod, the lost motion device being operable to absorb mechanical vibration of the cowl door
Implementation Method 2
the lost motion device being operable to absorb mechanical vibration of the cowl door and thermal expansion of the engine casing
Data Source
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AI summary
A system (40) for controlling the movement of an aircraft engine cowl door includes an actuator assembly (26) having a housing (60) and a screw shaft (68) arranged at least partially within a hollow interior of the housing (60). The screw shaft (68) is rotatable about an axis relative to the housing (60). A transmission system is coupled to the screw shaft (68) to impart rotation to the screw shaft (68) about the axis. A nut (80) is engaged with the screw shaft (68) and a piston rod (82) having a rod end mounted thereto connects the nut (80) to the cowl door (24) of the engine. The nut (80) is translatable relative to the screw shaft (68) to transition the cowl door between a first position and a second position.