YSZ Ceramic Fireproof Hose Structure for No-Flow Flame Resistance

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Solution Overview

Problem

Existing aerospace hoses fail to consistently meet stringent fireproofing requirements, such as AS1055 and TSO, due to degradation during fire exposure, leading to potential leakage and failure, especially when exposed to direct flames for extended periods.

Innovation Solution

A fireproof hose design featuring a flexible yttria-stabilized zirconia (YSZ) ceramic substrate layer sandwiched between silicone rubber layers, along with a metallic reinforcement and PTFE inner tube, which provides enhanced thermal shock resistance and prevents non-uniform char formation, ensuring compliance with 5-15 minute no-flow fire performance standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silicone covers are used for fire protection, then fire resistance is improved, but non-uniform char formation occurs and silicone may fall off exposing inner PTFE layer

Engineering Contradiction:

Improvefire resistanceVSAvoidchar uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by combining silicone rubber with expandable graphite to create a fireproof cover. The expandable graphite provides a stable, uniform char structure that prevents silicone from falling off, while maintaining fire resistance. This composite approach resolves the contradiction by adding a material that stabilizes the char formation without compromising the fire protective function.

Inventive Principle:

Principle #40Composite materials

2Reliability

If fire sleeves are added to meet zero flow AS1055 requirements, then fire performance is improved, but outer diameter increases and weight is added

Engineering Contradiction:

Improvefire performanceVSAvoidhose weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges the fire protective function directly into the hose construction by integrating a fireproof cover made of silicone rubber and expandable graphite onto the hose assembly. This eliminates the need for separate external fire sleeves, thereby achieving fire performance requirements without the additional weight and increased outer diameter that would result from adding separate fire sleeve components.

Inventive Principle:

Principle #5Merging (Combining)

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 hose effectively withstands direct flames for 15 minutes without failure, meeting AS1055 and TSO requirements, while offering a weight reduction and smooth outer diameter for easier clamping, maintaining structural integrity at high temperatures and reducing the risk of leakage.

Implementation Method 1

Methodology Applied

Scientific EffectThermal shock resistance: Thermal Shock

Implementation Method 2

The YSZ ceramic substrate layer(s) may be intermediate layer(s). For example, a YSZ ceramic substrate layer may be sandwiched between two silicone layers

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS12092240B2YSZ ceramic substrate protected fireproof hose

Publication Date: 2024.09.17 EATON INTELLIGENT POWER LTD

AI summary

A hose is provided capable of meeting fireproof requirements per AS1055 under no flow condition. The hose has multiple layers including a yttria-stabilized zirconia (YSZ) flexible ceramic substrate layer disposed between first and second silicone rubber layers.