Pneumatic Tire Belt-End Structure for Low Rolling Resistance

Solution Overview

Problem

Existing pneumatic tires face challenges in achieving both high durability and low rolling resistance, particularly at the belt ends, with issues such as belt edge separation and gap formation during tire production.

Innovation Solution

A pneumatic tire design with two belt layers, each having a thickness of 1.00 mm or less in the tire center, and specific cord and rubber configurations, along with end rubber placement to enhance durability and prevent gap formation, combined with a method of laminating the layers using asymmetric rubber sheets to ensure proper bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the thickness of belt layers is reduced to lower rolling resistance, then fuel efficiency improves, but durability at belt ends deteriorates

Engineering Contradiction:

Improverolling resistanceVSAvoiddurability at belt end

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent applies different thickness specifications for different regions of the belt layers. The center portion has thickness of 1.00 mm or less for low rolling resistance, while the end portions have increased thickness (1.20 mm or less) for enhanced durability. This local differentiation allows simultaneous optimization of both fuel efficiency and belt end durability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces end rubbers (first, second, and third end rubbers) at the belt ends before the belt layers terminate. These end rubbers are positioned in advance to prevent gap formation and reinforce the belt end structure, thereby improving durability without increasing the overall belt layer thickness in the center portion.

Inventive Principle:

Principle #10Preliminary action

2Weight of moving object

If belt layers are made thinner for weight reduction, then fuel efficiency improves, but gap formation at belt ends occurs during production

Engineering Contradiction:

Improvebelt layer weightVSAvoidgap formation at belt end

Core Design Contradiction:

Weight of moving objectVSManufacturing precision

Solution Approach 1:

The patent introduces end rubbers (first, second, and third end rubbers) at the belt ends before the belt layers terminate. These end rubbers are positioned in advance to prevent gap formation and reinforce the belt end structure, thereby improving durability without increasing the overall belt layer thickness in the center portion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies different thickness specifications for different regions of the belt layers. The center portion has thickness of 1.00 mm or less for low rolling resistance, while the end portions have increased thickness (1.20 mm or less) for enhanced durability. This local differentiation allows simultaneous optimization of both fuel efficiency and belt end durability.

Inventive Principle:

Principle #3Local quality

3Reliability

If cord spacing is increased at belt ends to prevent peeling, then durability improves, but rolling resistance increases

Engineering Contradiction:

Improvedurability at belt endVSAvoidrolling resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent defines specific cord spacing ratios for different regions: b/a = 1.8-4.0 at belt ends (where b is distance at end portion and a is distance at center portion), and c/d = 1.2-2.0 for interface cords. This local differentiation in cord spacing allows enhanced durability at belt ends while maintaining low rolling resistance in the center portion through tighter cord spacing.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250332867A1Pneumatic tire and method of producing the same

Publication Date: 2025.10.30 BRIDGESTONE CORP

AI summary

In a pneumatic tire, both of a thickness of the first belt layer and a thickness of the second belt layer in the tire center portion are 1.00 mm or less, and when the shortest distance between the cord of the second belt layer and the cord of the first belt layer in the tire center portion is defined as a, and the shortest distance between a cord closest to an end of the second belt layer and a cord of the first belt layer is defined as b, b/a is 1.8 to 4.0, and at an end of the belt, an end rubber is disposed in a predetermined manner on a tire radially inner side of the first belt layer, between the first belt layer and the second belt layer, and on a tire radially outer side the second belt layer.