Air Spring Bellows Intumescent Layer Fire Protection
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Solution Overview
Problem
Articles with elastomeric compounds used in vehicle suspension and vibration damping fail to meet stringent fire-protection standards due to high heat release rates and toxic combustion fumes, and traditional fire-retardant methods compromise physical properties.
Innovation Solution
A multilayer article with an inner layer, textile reinforcement layer, intermediate layer containing intumescent flame retardants like expandable graphite, and outer layer, where the intermediate layer is in direct contact with the reinforcement, delaying ignition and maintaining structural integrity during fires without compromising physical properties or increasing production complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fire-retardant substances are directly incorporated into rubber compounds to improve fire behavior, then fire protection is improved, but physical properties deteriorate due to increased hardness and reduced service life
Solution Approach 1:
The patent divides the fire protection function into separate layers: an inner layer with the elastomeric compound, reinforcement layers, and an outer layer containing fire-retardant substances (expandable graphite, magnesium hydroxide, aluminum trihydrate). This segmentation allows the fire-retardant substances to be positioned away from the dynamic load-bearing elastomeric compound, thus improving fire protection without compromising the physical properties and service life of the rubber compound.
Solution Approach 2:
The patent introduces an intermediate layer structure between the elastomeric compound and the fire-retardant substances. The outer layer acts as an intermediary that provides fire protection while the inner elastomeric layers maintain their dynamic suspension and vibration damping properties. This intermediary structure prevents the negative effects of fire-retardant substances from directly affecting the rubber compound's physical properties.
2Object-affected harmful factors
If expandable graphite is applied as a flame-retardant coating to protect the elastomeric body, then fire protection is improved, but device complexity increases due to additional coating layers and curing processes
Solution Approach 1:
The patent combines multiple fire-retardant substances (expandable graphite, magnesium hydroxide, aluminum trihydrate) into a single integrated outer layer formulation. This merging approach consolidates the fire protection function into one layer rather than requiring multiple separate coating applications, thus improving fire protection while avoiding the complexity of multiple curing processes and layer applications.
Solution Approach 2:
The outer layer is designed to serve multiple functions simultaneously: it provides fire protection through intumescent and hydroxide-based flame retardants, maintains structural integrity during fire exposure, and protects the underlying elastomeric layers. This multi-functionality reduces the need for additional specialized layers, thereby simplifying the overall device complexity while achieving comprehensive fire protection.
3Object-generated harmful factors
If halogen-free elastomeric compounds are used to meet fire protection standards, then combustion fumes toxicity is reduced, but heat release rate remains too high to meet maximum requirements
Solution Approach 1:
The patent employs a composite structure consisting of halogen-free elastomeric compounds in the inner layers combined with fire-retardant substances (expandable graphite, magnesium hydroxide, aluminum trihydrate) in the outer layer. This composite material approach allows the halogen-free elastomer to provide low toxicity combustion fumes while the outer fire-retardant layer controls the heat release rate by forming protective char layers and insulating the underlying elastomeric compound during fire exposure.
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 article exhibits delayed ignition of the reinforcement layer, maintaining functionality and meeting EN-45545 standards without degrading physical properties or increasing production complexity, as the intumescent layer forms a protective foam barrier, reducing the need for additional fire-retardant material.
Implementation Method 1
at least one intermediate layer C of the base unit is formed from a rubber compound that comprises 3 to 40 phr of at least one intumescent flame retardant
Implementation Method 2
The fire-protection property of expandable graphite in the outer coating as a flame-retardant substance
Data Source
AI summary
An article having a multilayer base unit with elastic properties has at least one inner layer A and at least one textile reinforcement layer B and at least one intermediate layer C and at least one outer layer D, at least one intermediate layer C of the base unit being formed from a rubber compound that includes chloroprene rubber (CR) or chlorosulfonated polyethylene (CSM) or alkylated chlorosulfonated polyethylene (ACSM) or chlorinated polyethylene (CM) or chlorobutyl rubber (CIIR) or bromobutyl rubber (BIIR) or polyepichlorohydrin rubber (CO; ECO; ETER) or brominated copolymer of isobutylene and paramethylstyrene (BIMS), in each case alone or in combination, and 3 to 40 phr of at least one intumescent flame retardant, and the intermediate layer C being in direct contact with a textile reinforcement layer B.