Compact Aircraft Actuator Layout for Large Steering Angles
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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 requiring steering angles beyond +/-60 degrees.
Innovation Solution
An aircraft actuation system utilizing a pinion, first and second cylinders with pistons, and a transfer member, such as a roller train, where the cylinders are disposed in parallel or non-parallel configurations, allowing for a compact design that reduces space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional linear rack & pinion actuators are used, then the actuator can provide sufficient steering angle (in excess of +/-60 degrees), but the cylinder overall length becomes excessively long, making it difficult to package within the aircraft installation envelope
Solution Approach 1:
The patent transitions from a linear rack configuration to a circular/rotational rack configuration. The rack is arranged in a circular path around the pinion gear, allowing the piston to move in a circular manner rather than linearly. This dimensional change enables the actuator to achieve large steering angles (exceeding +/-60 degrees) while maintaining a compact cylindrical overall length that fits within the aircraft installation envelope.
Solution Approach 2:
The patent employs a dynamic configuration where the rack is allowed to rotate and change position relative to the pinion during operation. The rack-pinion connection is designed to accommodate rotational movement, enabling the system to dynamically adjust the steering angle while maintaining a compact physical footprint. This dynamic approach allows the actuator to provide excessive +/-60 degrees steering capability without requiring a long cylinder length.
2Adaptability or versatility
If the cylinder length is reduced to fit within the aircraft installation envelope, then packaging becomes feasible, but the ability to achieve required steering angles may be compromised
Solution Approach 1:
The patent resolves this contradiction by changing the motion dimension from linear to circular. The rack is configured to move along a circular arc rather than a straight line, allowing the piston to achieve the necessary angular displacement within a compact cylindrical space. This enables the actuator to provide excessive +/-60 degrees steering capability while maintaining a short overall length that fits within the aircraft installation envelope.
Solution Approach 2:
The patent applies curvature by arranging the rack in a circular or arc-shaped configuration rather than a linear arrangement. The rack engages with the pinion gear in a rotational manner, allowing the piston to move through a circular path. This curved configuration enables the actuator to achieve large steering angles while maintaining a compact cylindrical form factor suitable for aircraft installation.
3Volume of stationary object
If a compact actuator design is implemented, then space requirements are reduced, but the device complexity increases due to the non-conventional configuration
Solution Approach 1:
The patent achieves compactness by designing a multi-functional actuator where the same circular rack-pinion mechanism provides both the steering actuation and the large angular displacement capability. The cylindrical housing serves multiple purposes: containing the piston, guiding the circular rack motion, and providing the external mounting interface. This universal design reduces the need for separate components, thereby reducing overall volume while managing complexity through functional integration.
Solution Approach 2:
The patent combines multiple functions into a single integrated actuator unit. The circular rack simultaneously serves as the motion transfer element, the angular displacement mechanism, and part of the structural framework. The piston, rack, and pinion are integrated into a single cylindrical assembly, eliminating the need for separate linear rack and mounting structures. This merging of functions reduces the overall actuator volume while keeping the design manageable through functional consolidation.
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 achieves reduced space requirements, enabling efficient actuation of aircraft components like landing gear and doors, while maintaining flexibility in installation configurations.
Implementation Method 1
a transfer member (e.g., a roller train) that is interconnected with each of the first piston and the second piston. 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
Implementation Method 2
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
Implementation Method 3
A first flow may be directed into the first cylinder to move the first piston within the first cylinder toward its corresponding first cylinder end in response to this first flow
Data Source
Figure 1
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Figure 3A
AI summary
An aircraft actuation system (300) is disclosed that includes a pair of cylinders (322a, 322b), a piston (330) movably disposed in each cylinder, and a roller train (340) that extends between the pistons in the two cylinders. A portion of the roller train is disposed beyond the cylinders to engage a pinion (302). 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 (332) 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 (390) may be used to maintain rollers (350) of the roller train in a proper orientation for entry into a space between an outer race and the pinion.