Self-Sealing Tire Structure for Low Off-Gassing Vulcanization
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Solution Overview
Problem
Current methods for manufacturing self-sealing pneumatic tires face challenges such as off-gassing during vulcanization, leading to undesirable expansion of the innerliner and issues with tire uniformity and balance.
Innovation Solution
A method involving an uncured pneumatic tire with a sealant layer encapsulated in a relatively stiff rubber formulation, which breaks down during vulcanization to form additional sealant material, reducing off-gassing and maintaining tire uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a degraded rubber sealant layer is assembled into the unvulcanized tire, then the tire achieves puncture sealing capability, but the degraded rubber becomes tacky and difficult to handle during manufacturing
Solution Approach 1:
The patent divides the sealant system into two distinct layers: an outer undegraded rubber layer that provides structural integrity and ease of handling during manufacturing, and an inner degraded rubber layer that provides the puncture sealing capability. This segmentation allows each layer to perform its specific function without compromising the other.
Solution Approach 2:
The degraded rubber sealant layer is nested within or between layers of undegraded rubber. This nesting structure allows the tacky degraded rubber to be contained and supported by the stronger undegraded rubber layers, making the entire assembly easy to handle during tire building while maintaining the sealing function of the inner layer.
2Strength
If a lamination procedure is used to support the degraded rubber layer, then the tire maintains structural integrity during building, but the manufacturing cost increases greatly
Solution Approach 1:
The patent merges the structural support function and the sealant function into a single integrated tire structure. The undegraded rubber layers serve dual purposes: providing structural integrity during tire building and simultaneously supporting the degraded rubber sealant layer, eliminating the need for separate lamination procedures.
Solution Approach 2:
The undegraded rubber layers perform multiple functions: they provide the structural framework of the tire, maintain integrity during manufacturing, support the degraded rubber sealant layer, and contribute to the overall sealing capability. This multi-functionality reduces the need for additional components and procedures.
3Reliability
If fluid puncture sealant coatings are used, then the sealant flows into puncture holes, but the sealant may flow excessively causing tire imbalance
Solution Approach 1:
The patent creates a sealant system with spatially varying properties: the degraded rubber layer is positioned specifically between the innerliner and carcass where punctures are most likely to occur, and its viscosity is optimized for local sealing action. The undegraded rubber layers provide structural stability to prevent excessive flow in other areas, maintaining tire balance.
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 approach allows for the production of self-sealing tires with improved uniformity and balance, as well as reduced manufacturing costs, by minimizing off-gassing and eliminating the need for complex lamination procedures.
Implementation Method 1
the sealant layer is encapsulated by a relatively stiff composition, wherein the relatively stiff composition breaks down at temperatures typically used for vulcanization and forms a sealant material
Implementation Method 2
breaks down at temperatures typically used for vulcanization
Data Source
Figure 1~2
Figure 3
AI summary
An uncured pneumatic tire and a method of manufacturing a pneumatic rubber tire having a puncture sealing feature is disclosed. The uncured pneumatic tire comprises a generally toroidal-shaped supporting carcass (4, 14, 24) with an radially outer circumferential tread (8, 11, 28), two spaced beads (5, 15, 25), at least one ply extending from bead to bead, sidewalls (3, 13, 23) extending radially from and connecting said tread to said beads, and a sealant layer (7, 17, 27) which is disposed radially inwardly from the supporting carcass (4, 14, 24). The sealant layer (7, 17, 27) is located (i) radially between two layers of an innerliner (6, 16) or (ii) radially between said supporting carcass (4, 14, 24) and a radially inner containment layer (26) or (iii) radially between an innerliner layer (6, 16) and a containment layer (26). The circumferential tread (8, 11, 18) is adapted to be ground-contacting. The sealant layer (7, 17, 27) is encapsulated by a relatively stiff composition, wherein the relatively stiff composition is configured to break down at temperatures used for tire vulcanization and to form a sealant material, wherein the relatively stiff material does not interfere with the function of surrounding tire components, and wherein the sealant layer (7, 17, 27) comprises a relatively low viscosity material that preferably requires only little or no depolymerization to act as a sealant material.