Run-flat Tire Smooth Inner Cavity Heat Dissipation
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Solution Overview
Problem
Run-flat tires face durability issues due to heat accumulation in the sidewall portion during run-flat running, which can lead to breakage, despite previous attempts to address this with high thermal conductivity rubber and concavo-convex patterns.
Innovation Solution
A run-flat tire design featuring a smooth inner-cavity surface with a side-reinforcement rubber layer, where the smooth surface area exceeds 90% of the total side inner-cavity surface area, and a rigid core with segments arranged in the circumferential direction to prevent heat accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a side-reinforcement rubber layer with high thermal conductivity is used in the sidewall portion, then heat dissipation is improved, but the complexity of the tire structure increases
Solution Approach 1:
The invention extracts the heat dissipation function from the rubber material itself and relocates it to the inner-cavity surface geometry. By creating a smooth side inner-cavity surface, the tire structure utilizes thermal radiation and convection directly at the heat generation location, eliminating the need for specialized high-thermal-conductivity rubber compounds and their associated complexity.
Solution Approach 2:
The smooth side inner-cavity surface acts as an intermediary between the heat-generating side-reinforcement rubber layer and the tire interior environment. This smooth surface facilitates efficient heat transfer to the air inside the tire cavity through radiation and convection, serving as a thermal interface that improves heat dissipation without modifying the rubber material properties.
2Temperature
If concavo-convex patterns are added to the outer surface of the sidewall portion, then radiation performance is improved, but the manufacturing complexity increases
Solution Approach 1:
Instead of modifying the outer sidewall surface with concavo-convex patterns to improve heat dissipation, the invention inverts the approach by modifying the inner-cavity surface. The smooth side inner-cavity surface directly faces the heat-generating side-reinforcement rubber layer, enabling efficient heat transfer from the source without the manufacturing complexity of external patterns.
Solution Approach 2:
The invention applies the smooth surface treatment locally to the side inner-cavity surface, specifically in the region corresponding to the side-reinforcement rubber layer. This localized approach targets the heat dissipation function precisely where needed, without requiring complex patterns across the entire sidewall outer surface.
3Reliability
If the side-reinforcement rubber layer is made thicker to improve run-flat performance, then durability is improved, but heat accumulation increases
Solution Approach 1:
The invention addresses heat accumulation by introducing a new dimension for heat dissipation - the inner-cavity surface geometry. Instead of merely increasing thickness in one dimension, the smooth side inner-cavity surface creates an additional thermal pathway in the radial direction, allowing heat to escape inward toward the tire cavity while maintaining the structural thickness needed for run-flat performance.
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 smooth surface design effectively suppresses local heat accumulation, enhancing the durability of the tire during run-flat conditions.
Implementation Method 1
the side inner-cavity surface includes a smooth surface which does not have unevenness, and the total surface area of the smooth surface is more than 90% of the total area of the side inner-cavity surface... local heat accumulation in the sidewall portion during run-flat running is prevented
Data Source
AI summary
It is a run-flat tire 1 provided with a carcass 6 extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 in a bead portion 4, and a side-reinforcement rubber layer 10 disposed inside the carcass 6 in the sidewall portion 3 and having a substantially crescent-shaped cross-section. In a tire meridian cross section including the tire rotational axis under a normal state such that the tire is mounted on a normal rim, inflated to a normal internal pressure and loaded with no load, the tire inner-cavity surface 11 includes a side inner-cavity surface 12. A distance in the tire radial direction of the side inner-cavity surface 12 from a bead toe 4e of the bead portion 4 is in a range of 0.4 times to 0.9 times the length H in the tire radial direction of the tire inner-cavity surface 11. The side inner-cavity surface 12 includes a smooth surface 15 which does not have unevenness, and the total surface area of the smooth surface 15 is more than 90% of the total area of the side inner-cavity surface 12.