Triplex Tandem Hydraulic Actuator Ballistic Protection

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Solution Overview

Problem

Current linear hydraulic actuators used in aircraft lack full-triplex redundancy and ballistic protection, with side-by-side configurations being unsuitable for military applications due to size and weight constraints, and existing solutions either lack reliability or are excessively large.

Innovation Solution

A triplex tandem actuator configuration with two armored and one unarmored concentric cylinders, featuring through-the-ram leakage vent holes and a sensing port for damaged gland seal detection, eliminates switching valves and provides full triplex redundancy while maintaining a compact size and weight similar to dual tandem actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If three cylinders are positioned side by side in a triangular configuration to provide full triplex redundancy, then reliability is improved, but the actuator envelope and weight increase excessively making it unsuitable for military applications

Engineering Contradiction:
Improvefull-triplex redundancyVSAvoidactuator weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent implements a nested concentric cylinder configuration where an inner cylinder is positioned within an outer cylinder, both sharing a common ram. This nesting arrangement allows three hydraulic systems to control the same ram through different cylinder-piston combinations, achieving full triplex redundancy while maintaining a compact actuator envelope and weight comparable to dual-actuator systems.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If three cylinders are positioned side by side in a triangular configuration to provide full triplex redundancy, then reliability is improved, but the actuator envelope size increases excessively

Engineering Contradiction:
Improvefull-triplex redundancyVSAvoidactuator envelope
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent implements a nested concentric cylinder configuration where an inner cylinder is positioned within an outer cylinder, both sharing a common ram. This nesting arrangement allows three hydraulic systems to control the same ram through different cylinder-piston combinations, achieving full triplex redundancy while maintaining a compact actuator envelope and weight comparable to dual-actuator systems.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If all three exposed rams and cylinders are armored to provide ballistic protection, then ballistic tolerance is improved, but the actuator complexity and weight increase

Engineering Contradiction:
Improveballistic protectionVSAvoidactuator complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the function of three separate armored cylinders into a single integrated concentric cylinder assembly with shared components including a common ram, shared seals, and integrated hydraulic connections. This consolidation achieves ballistic protection for all three hydraulic systems while reducing overall complexity compared to three separate armored actuators.

Inventive Principle:
Principle #5Merging (Combining)

4Device complexity

If switching valves are used to allow one of two hydraulic systems to power one of two cylinders, then device complexity is reduced, but reliability decreases by eliminating full triplex redundancy

Engineering Contradiction:
Improvevalve system simplicityVSAvoidtriplex redundancy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent segments the hydraulic power transmission path into three independent routes through the concentric cylinders, allowing each of the three hydraulic systems to independently power the actuator through different cylinder-piston combinations. This eliminates the need for switching valves while maintaining full triplex redundancy, as any single system failure does not prevent actuator operation.

Inventive Principle:
Principle #1Segmentation

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 triplex tandem actuator achieves improved ballistic tolerance, reliability, and compactness, enabling critical flight control actuation for military aircraft with minimal envelope or weight impact, ensuring continued operation even after damage to one cylinder.

Implementation Method 1

a pressure source selectively powered from any one of three independent hydraulic systems is adapted to selectively power any one of three tandem linear hydraulic actuators

Methodology Applied
Scientific EffectHydraulic pressure transmission: Pascal's Law

Data Source

PatentEP2016291B1Ballistically tolerant linear hydraulic actuator
Publication Date: 2013.04.03 BELL HELICOPTER TEXTRON INC
  • EP2016291B1 patent drawingFigure 1
  • EP2016291B1 patent drawingFigure 2~3
  • EP2016291B1 patent drawingFigure 4

AI summary

A hydraulic actuator has an armored section having concentric cylinders and an unarmored section having a cylinder with a frangible piston and a frangible upper gland nut. The hydraulic actuator may have leakage vents adapted to prevent leakage between hydraulic systems used to power the cylinders. The hydraulic actuator also may have a gland seal for sealing an end of the cylinder of the unarmored section and a sensing port adapted for allowing detection of fluid leaking due to damage of the gland seal.