Compact Aircraft Actuator Layout for Tight Installation Space
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Solution Overview
Problem
Conventional linear rack & pinion actuators have a long cylinder overall length, making it difficult to package them within the limited space requirements of aircraft installations, especially for steering applications that require steering angles beyond ±60 degrees.
Innovation Solution
An aircraft actuation system comprising a pinion, two non-collinear cylinders with pistons, and a transfer member, such as a roller train, that moves the pinion to provide actuation force for steering, landing gear deployment, retraction, and door operations, with the cylinders disposed in parallel or angled orientations to optimize space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional linear rack & pinion actuators are used, then the actuation force is sufficient for steering applications, but the cylinder overall length becomes excessively long
Solution Approach 1:
The patent transitions from a linear rack configuration to a circular rack configuration that engages the pinion radially. This dimensional change allows the actuator to achieve the same rotational output through a compact circular path rather than a long linear extension, dramatically reducing the cylinder length while maintaining sufficient actuation force for steering applications
Solution Approach 2:
The invention employs a circular rack with curved engagement surfaces that rotate around the pinion gear. This curved/spheroidal configuration replaces the straight linear rack, enabling the system to deliver the required torque and actuation force through rotational motion in a compact envelope, thereby solving the length issue while preserving force capability
2Device complexity
If conventional linear rack & pinion actuators are used, then the actuation mechanism is simple, but the packaging within aircraft installation envelope becomes extremely difficult
Solution Approach 1:
By changing from linear to circular rack geometry, the actuator footprint transforms from a long narrow profile to a compact circular arrangement. This dimensional reconfiguration allows the system to fit within the limited radial and axial spaces available in aircraft installations, making packaging feasible without significantly increasing overall device complexity
Solution Approach 2:
The circular rack design integrates the rack and pinion interaction within a unified rotational mechanism, where the rack itself rotates around the pinion. This merging of functions into a compact circular assembly reduces the spatial requirements compared to separate linear components, facilitating installation within constrained aircraft envelopes
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 system effectively reduces space requirements by up to 60% compared to traditional linear racks, allowing for flexible installation configurations and efficient operation of aircraft components like nose landing gear and doors.
Implementation Method 1
a transfer member (e.g., a roller train) that is interconnected with each of the first piston and the second piston. At least part of the transfer member is disposed out of each of the first and second cylinders and is engaged with the pinion. Movement of the first piston and the second piston within the first cylinder and the second cylinder, respectively, moves the transfer member to rotate the pinion.
Data Source
AI summary
An aircraft actuation system is disclosed that includes a pair of cylinders, a piston movably disposed in each cylinder, and a roller train that extends between the pistons in the two cylinders. A portion of the roller train is disposed beyond the cylinders to engage a pinion. Movement of the pistons in the two cylinders in opposite directions produces a corresponding movement of the roller train to in turn rotate the pinion. The roller train may be maintained in compression between its two ends by fluid pressure exerted on a common face of each of the pistons in the two cylinders. The cylinders may be disposed in non-colinear relation, including in parallel relation to one another. A guide may be used to maintain rollers of the roller train in a proper orientation for entry into a space between an outer race and the pinion.