Run-flat Tire Sidewall Reinforcement Geometry
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Solution Overview
Problem
Run-flat tires with crescent-like side reinforcing rubber face a trade-off between high fuel efficiency and durability due to weight increases, making it challenging to achieve both in narrow-width, large-diameter designs.
Innovation Solution
A run-flat tire design with specific dimensional ratios for sectional width to outer diameter and strategically placed side reinforcing rubbers, along with a toroidally arranged carcass and bead structures, optimizes fuel efficiency and durability by reducing air resistance and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If side reinforcing rubber with crescent-like cross section is added to improve run-flat durability, then run-flat durability is improved, but weight increases causing deteriorated fuel efficiency
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dimensional parameters of the side reinforcing rubber. Specifically, it sets the ratio relationship between the maximum width W1 and maximum length H1 of the crescent-like cross-section, and controls the thickness T1 to satisfy specific numerical ranges. This optimized parameter configuration achieves the necessary run-flat durability while minimizing the volume and weight of the side reinforcing rubber, thereby resolving the contradiction between durability improvement and weight control.
2Use of energy by moving object
If narrow-width, large-diameter tire is used to improve fuel efficiency, then fuel efficiency is improved, but run-flat travelling performances are compromised
Solution Approach 1:
The patent applies local quality by strategically positioning the side reinforcing rubber with crescent-like cross-section at specific locations on the sidewall. The crescent shape is oriented with its opening facing the tread center, and its dimensions are locally optimized to provide maximum structural support exactly where needed for run-flat performance, while keeping other areas of the tire lightweight for fuel efficiency.
Solution Approach 2:
The patent establishes specific parameter relationships for narrow-width tires (SW < 165mm), setting the ratio SW/OD to be 0.26 or less, and controlling the side reinforcing rubber dimensions to satisfy 10(mm) ≤ (SW/OD)×H1 ≤ 20(mm). These parameter changes enable narrow-width tires to achieve both fuel efficiency and adequate run-flat performance.
3Strength
If side reinforcing rubber volume is increased to maintain structural integrity, then structural integrity is improved, but air resistance increases reducing fuel efficiency
Solution Approach 1:
The patent optimizes the volume of side reinforcing rubber by controlling the dimensional parameters of the crescent-like cross-section. It sets the thickness T1 to be 5mm or less, and establishes the ratio relationship between width W1 and length H1, ensuring that (W1/H1)×100 is within 30-70%. These parameter changes minimize the protruding volume of the side reinforcing rubber, reducing air resistance while maintaining sufficient structural integrity for run-flat durability.
Data Source
Figure 1
AI summary
The run-flat tire of this disclosure includes a tread portion, a pair of sidewall portions continuous, bead portions, side reinforcing rubbers with crescent-like cross section, and a carcass, wherein: when the tire is mounted to a rim, and an internal pressure of 250 kPa or more is applied to the tire, in a case where a sectional width SW of the tire is less than 165 mm, a ratio of the sectional width SW to an outer diameter OD of the tire, SW/OD, is 0.26 or less; and in a case where the sectional width SW of the tire is 165 mm or more, the sectional width SW and the outer diameter OD of the tire satisfy a relation expression OD≥2.135×SW+282.3 (mm); and when H1 is a tire radial maximum length of the side reinforcing rubber in a tire widthwise cross section in a reference state where the tire is mounted to a rim, applied a predetermined internal pressure and applied no load, a relation expression 10(mm)≤(SW/OD)×H1≤20(mm) is satisfied.