Hydraulic Actuator with Floating Pistons for Aircraft Redundancy
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Solution Overview
Problem
Conventional hydraulic actuator systems for aircraft are heavy, costly, and have safety concerns due to redundancy configurations that require duplicate cylinders and switching valves, which can lead to weight inefficiencies and system instability in case of failures.
Innovation Solution
A hydraulic actuator design with a housing and piston assembly featuring a ram with a first piston and two translatable pistons, forming two hydraulically separate actuator cylinders, allowing for automatic switching between systems without a switching valve, reducing weight, size, and complexity, while maintaining fail-safe redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplicate hydraulic cylinders are used for redundancy, then safety is improved, but weight increases
Solution Approach 1:
The patent combines two redundant hydraulic cylinders into a single integrated actuator with a shared housing and common rod end. The first and second hydraulic cylinders are merged such that they share structural components including the housing, rod end, and linkage connections, while maintaining separate piston assemblies for redundancy. This merging reduces the overall weight compared to using two completely separate cylinders while preserving the fail-safe redundancy capability.
2Reliability
If duplicate hydraulic cylinders are used for redundancy, then safety is improved, but system complexity increases
Solution Approach 1:
The patent merges multiple hydraulic cylinder functions into a single integrated actuator assembly. The shared housing, common rod end, and unified linkage system reduce the number of separate components and connections required, thereby simplifying the overall system architecture while maintaining redundant hydraulic pathways for safety.
Solution Approach 2:
The single actuator assembly performs multiple functions: it provides primary hydraulic actuation through the first piston assembly, maintains standby redundancy through the second piston assembly, and automatically switches between systems upon failure detection. The shared structural components serve both cylinders simultaneously, reducing system complexity while enabling multi-functionality.
3Reliability
If oversized hydraulic cylinders are used to account for failure scenarios, then safety is improved, but weight increases
Solution Approach 1:
The patent segments the hydraulic actuator into two independent but integrated piston assemblies within a single cylinder. Each piston assembly can operate independently to provide the required output force, eliminating the need for a single oversized cylinder. The segmentation allows each subsystem to be optimally sized while maintaining redundancy, thereby reducing overall weight compared to using one oversized cylinder capable of handling failure scenarios alone.
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
This configuration reduces the weight and size of the hydraulic actuator, provides optimal sizing for aircraft structures, ensures safe operation by eliminating viscous damping losses, and meets safety standards by maintaining output force with single or dual system pressurization, thus reducing manufacturing costs and enhancing system reliability.
Implementation Method 1
a first piston disposed on the shaft within the housing chamber, a second piston moveably disposed on the shaft within the housing chamber, and a third piston moveably disposed on the shaft within the housing chamber
Data Source
AI summary
A hydraulic actuator is configured to provide redundant boost control to an aircraft within approximately the same space required by a single hydraulic cylinder. The hydraulic actuator includes a housing and a piston assembly disposed within the housing. The piston assembly includes a ram, a first piston secured to the ram, and second and third pistons disposed on the ram such that the second and third pistons are translatable relative to the longitudinal axis of the ram. The pistons form two hydraulically separate actuator cylinders within the space required by a single cylinder which results in a reduction in the weight and size of the hydraulic actuator.