Macrocellular Polyolefin Foam Sound Absorption in Tyre Cavities
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Solution Overview
Problem
Conventional soundproof tires face challenges with noise reduction due to cavity resonance, as existing sound absorbent materials like polyurethane foams degrade under mechanical and thermal stresses, and suffer from hygroscopicity issues, leading to comfort and safety concerns.
Innovation Solution
The use of macrocellular polyolefin foams with closed cells, which are resistant to thermal and mechanical stresses, maintain acoustic performance, and are non-hygroscopic, providing improved durability and reduced moisture absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane foams are used as sound absorbent material in tyre inner cavity, then sound absorption performance is improved, but the material degrades under thermal and mechanical stresses and absorbs moisture leading to reduced reliability
Solution Approach 1:
The patent changes the material parameters by selecting polyolefin foam instead of polyurethane foam, which has different thermal stability, mechanical resistance, and hygroscopicity parameters. This material substitution resolves the degradation and moisture absorption issues while maintaining sound absorption performance
Solution Approach 2:
The patent uses composite construction by combining the polyolefin foam with the tyre liner and other tyre components. The foam is integrated into the tyre structure as a composite system, allowing the sound absorbent material to function reliably under tyre operating conditions
2Object-generated harmful factors
If sound absorbent materials are introduced into the inner cavity of tyres, then cavity noise is reduced, but the materials are subjected to considerable mechanical and thermal stresses causing degradation
Solution Approach 1:
The patent changes the thermal and mechanical resistance parameters of the sound absorbent material by selecting polyolefin foam, which has higher melting point and better stress resistance compared to conventional polyurethane foams. This allows the material to withstand tyre operating conditions while absorbing cavity noise
Solution Approach 2:
The patent employs a sound absorbent material that is designed to withstand the harsh tyre environment for the entire service life of the tyre. The polyolefin foam is selected for its durability and resistance to degradation, ensuring long-term reliability rather than requiring replacement
3Reliability
If polyurethane foams with open cells are used for sound absorption and heat dispersion, then acoustic performance is improved, but the foams absorb moisture from environment leading to bacterial growth and hydrolytic degradation
Solution Approach 1:
The patent changes the hygroscopicity parameter by selecting polyolefin foam, which is inherently hydrophobic and does not absorb moisture. This eliminates the problems of bacterial growth and hydrolytic degradation while maintaining the open cell structure for sound absorption and heat dispersion
Solution Approach 2:
The patent adopts the successful open cell foam structure from polyurethane applications but copies it using polyolefin material, which has the advantageous property of being non-hygroscopic. This allows replication of the effective acoustic and thermal performance without the moisture-related drawbacks
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
These foams offer comparable or improved sound absorption performance to polyurethane foams, enhancing tire durability, comfort, and safety by resisting degradation and moisture absorption, while simplifying production and storage processes.
Implementation Method 1
The sound absorbent material is capable of removing sound waves, converting the energy of the incident sound into heat
Implementation Method 2
the materials are heated well over the ambient temperature, due to the heat generated by the tread in use on the road... the sound absorbent foams possess good thermal as well as mechanical properties in order to avoid being degraded
Implementation Method 3
during the rolling, on one hand the materials are continuously stretched due to the tyre deformation
Data Source
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AI summary
Soundproof tyre (100) along with a process for the production thereof, wherein the tyre comprising particular polyolefin sound absorbent foams that show damping performances for the noise generated in the cavity of such tyre, together with resistance to hydrolysis, poor water absorption and an unexpected thermal and mechanical stability in use conditions, wherein the sound absorbent material (301) is applied at least on one portion of the radially inner surface (113) of the tyre, preferably of the impermeable elastomeric material layer (112), wherein said sound absorbent material comprises a foamed polyolefin material with closed macrocells characterised by an average size of at least 1.5 mm, more preferably of at least 3 mm, still more preferably of at least 4 mm according to ASTM D3576.