Central Rotary Actuator Assembly for Leak-Sensitive Load Holding
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Solution Overview
Problem
Rotary hydraulic actuators face challenges in achieving leak-free performance and positional accuracy due to internal leakage characteristics, which is critical in applications like aircraft flight control where continuous load holding is required without external fluid power supply.
Innovation Solution
A rotary actuator design incorporating a bearing assembly within axial apertures and arcuate-shaped pistons that reciprocate within pressure chambers, using a central actuation assembly for attachment to aircraft structural members, allowing for compact and lightweight actuation with reduced deformation between mounting points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If rotary vane or rotary piston configurations are used to achieve compact actuation, then device size is reduced, but internal leakage characteristics worsen and positional accuracy deteriorates
Solution Approach 1:
The actuator is divided into two separate rotary actuator assemblies (first and second) that are removably coupled together. Each assembly contains its own rotor, pistons, and mounting features. This segmentation allows the internal leakage issues of rotary mechanisms to be contained within modular units while maintaining compact overall size, and enables replacement or repair of individual assemblies to maintain positional accuracy.
Solution Approach 2:
The two rotary actuator assemblies are nested or coupled together with their actuation arms connected, creating a compact integrated structure where the output of one assembly drives the input of the other. This nesting maintains the space-saving benefits of rotary design while the dual-assembly configuration helps mitigate internal leakage effects on positional holding.
2Ease of manufacture
If traditional mounting assemblies are used at the ends of the actuator housing, then ease of manufacture is improved, but deformation between mounting points increases
Solution Approach 1:
The mounting function is segmented from the main housing and implemented as separate mounting assemblies attached to each rotary actuator assembly. These mounting assemblies include bearing assemblies with radial and axial bearings that are integrated into the rotary assemblies rather than being part of the housing, reducing stress and deformation on the housing structure.
Solution Approach 2:
Bearing assemblies serve as intermediary elements between the rotary actuator assemblies and the external mounting features. The bearing assemblies (including spherical bearings with radial and axial components) mediate the mechanical loads and reduce deformation by providing proper load paths and support points, while the mounting assemblies themselves are designed to be removable and replaceable to facilitate maintenance.
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 design provides improved positional holding and reduced deformation, enabling efficient rotary actuation in compact spaces, suitable for aircraft applications, while maintaining the compactness and light weight of rotary vane actuators.
Implementation Method 1
a bearing assembly disposed within at least one of the first axial aperture and the second axial aperture and having a radially outer surface in contact with at least one of the first mounting assembly and the second mounting assembly, and a radially inner surface in contact with at least one of the first rotor assembly and the second rotor assembly
Implementation Method 2
arcuate-shaped pistons that reciprocate within pressure chambers, using a central actuation assembly for attachment to aircraft structural members
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a rotary actuator that includes a first rotary actuator assembly having a first housing, a first mounting assembly radially projecting from a first longitudinal end of the first housing and defining a first axial aperture, and a first output shaft extending into the first axial aperture, a second rotary actuator assembly having a second housing, a second mounting assembly radially projecting from a second longitudinal end of the second housing and defining a second axial aperture, and a second output shaft extending into the second axial aperture, and a bearing assembly having an outer surface in contact with at least one of the first mounting assembly and the second mounting assembly, and an inner surface in contact with at least one of the first rotor assembly and the second rotor assembly.