Run-Flat Tire Inner Liner Layout for Lower Rolling Resistance
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Solution Overview
Problem
Run-flat tires with side reinforcing rubbers experience increased rolling resistance and potential deterioration in run-flat durability due to internal pressure decreases.
Innovation Solution
A run-flat tire design featuring a carcass with side reinforcing rubbers and inner liners that taper in cross-section, reducing rolling resistance and ensuring durability by suppressing gas transmission and bead collapse during run-flat operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If side reinforcing rubbers are provided at the tire side portions to enable run-flat operation, then run-flat capability is improved, but rolling resistance increases
Solution Approach 1:
The inner liner is designed with varying thickness across different regions: thinner at the side portions (reducing rolling resistance) and thicker at the crown portion (maintaining airtightness). This local variation in material distribution allows the tire to maintain run-flat capability while minimizing energy loss during normal rolling operation.
2Loss of energy
If the inner liner is made thinner to reduce rolling resistance, then rolling resistance decreases, but airtightness may deteriorate
Solution Approach 1:
The inner liner thickness is optimized for each region: thinner at the side portions where rolling resistance is critical, and thicker at the crown portion where airtightness is most important. This spatially varying thickness profile simultaneously addresses both rolling resistance reduction and airtightness maintenance.
Solution Approach 2:
The inner liner incorporates a tapering structure in the radial direction, creating a three-dimensional thickness variation rather than a uniform planar structure. This dimensional approach allows the liner to be thin where needed for low rolling resistance while remaining thick where needed for airtightness.
3Reliability
If the inner liner extends to the inner side end portions of the side reinforcing rubbers, then airtightness is improved, but rolling resistance increases
Solution Approach 1:
The inner liner is strategically positioned with reduced thickness at the side portions and extended coverage at the crown portion. This localized material distribution provides sufficient airtightness at the bead and crown regions while minimizing the liner's presence in the side portions where it would increase rolling resistance.
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 design effectively decreases rolling resistance and maintains run-flat durability, improving fuel efficiency and riding comfort while preventing excessive bead and tire side portion collapse.
Implementation Method 1
a first inner liner provided along a tire radial direction inner side surface of the carcass central portion and tire width direction inner side surfaces of the side reinforcing rubbers
Implementation Method 2
side reinforcing rubbers provided along tire width direction inner side surfaces of the carcass side portions, and formed in shapes that taper respectively toward a tire radial direction inner side and a tire radial direction outer side
Data Source
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AI summary
A run-flat tire including side reinforcing rubbers provided along tire width direction inner side surfaces of carcass side portions, a first inner liner provided along a tire radial direction inner side surface of the carcass central portion and tire width direction inner side surfaces of the side reinforcing rubber, both end portions of the first inner liner running along a contour in a cross-section along a tire rotational axis direction and being respectively formed further toward a tire radial direction outer side than tire radial direction inner side end portions of the side reinforcing rubber; and a second inner liner extending along a surface, which is at a side opposite from the carcass central portion, of the first inner liner, both end portions of the second inner liner being respectively formed further toward a tire radial direction inner side than the both end portions of the first inner liner, along a contour in a cross-section along the tire rotational axis direction.