Pneumatic Tire Dual-Layer Tread Design
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Solution Overview
Problem
Current pneumatic tires face challenges in achieving balanced fuel efficiency, handling stability, and durability, as reducing filler content to improve fuel efficiency can lead to reduced stiffness and durability issues, while increasing crosslink density compromises abrasion resistance.
Innovation Solution
A pneumatic tire design featuring a tread with a cap layer and a base layer, where the base layer is harder than the cap layer, and their specific volume and viscoelastic properties are optimized to enhance driving stiffness, fuel efficiency, and durability, using butadiene rubber with 1,2-syndiotactic polybutadiene crystals and specific formulations for each layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If filler content is reduced to improve fuel efficiency, then rolling resistance decreases and fuel efficiency improves, but tread stiffness is reduced and handling stability deteriorates
Solution Approach 1:
The tread is divided into two layers with different rubber compositions and properties. The base layer uses a rubber composition optimized for low rolling resistance and high fuel efficiency, while the cap layer uses a rubber composition optimized for high stiffness and handling stability. This local differentiation allows each layer to perform its specific function without compromising the other.
Solution Approach 2:
The tread employs a composite structure combining two different rubber compositions in specific volume ratios. The base layer and cap layer are made from rubber compositions with different filler contents, crosslink densities, and physical properties, creating a composite material system that achieves both fuel efficiency and handling stability.
2Strength
If crosslink density is increased to enhance tread stiffness, then handling stability improves, but abrasion resistance and chipping resistance deteriorate
Solution Approach 1:
The cap layer is designed with high crosslink density (2.5-4.0 parts by weight of sulfur per 100 parts by weight of rubber component) to provide the necessary stiffness for handling stability, while the base layer uses lower crosslink density (1.5-3.0 parts by weight of sulfur per 100 parts by weight of rubber component) to maintain flexibility and resistance to cracking and chipping.
Solution Approach 2:
The dual-layer tread structure allows the cap layer to be made from a rubber composition with high crosslink density for stiffness, while the base layer uses a rubber composition with optimized lower crosslink density for durability. This composite approach enables the system to achieve both handling stability and resistance to abrasion and chipping.
3Strength
If base layer is made harder to improve driving stiffness and fuel efficiency, then rolling resistance decreases, but the tan δ increases which may affect fuel efficiency
Solution Approach 1:
The base layer rubber composition is carefully formulated with specific physical parameters: hardness of 60-75 degrees Shore A, complex modulus of 4.0-9.0 MPa, and tan δ of 0.050-0.190 at 30°C. These parameter optimizations allow the base layer to provide sufficient driving stiffness while minimizing energy loss through controlled hysteresis.
Solution Approach 2:
The base layer uses a rubber composition with specific filler content (20-50 parts by weight per 100 parts by weight of rubber component) and controlled crosslink density to achieve the optimal balance between hardness for driving stiffness and tan δ for energy loss. The cap layer then provides additional stiffness without significantly increasing energy loss.
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 tire achieves improved fuel efficiency, handling stability, and durability by satisfying specific relationships between the cap and base layers' volumes, complex modulus, and loss tangents, resulting in better driving performance and longer tire life.
Implementation Method 1
the base layer comprises butadiene rubber containing a 1,2-syndiotactic polybutadiene crystal
Implementation Method 2
E*c and tan δc are a complex modulus and a loss tangent, respectively, of the cap layer at 30°C, and E*b and tan δb are a complex modulus and a loss tangent, respectively, of the base layer at 30°C
Data Source
Figure 1
AI summary
Provided is a pneumatic tire capable of improving fuel efficiency, handling stability, and durability in a balanced manner. The present invention relates to a pneumatic tire, comprising a tread that includes a cap layer and a base layer, the cap layer and the base layer satisfying relationships represented by the following formulas (1) to (3): wherein Vc is the volume of the cap layer and Vb is the volume of the base layer, and wherein E*c and tan δc are the complex modulus and the loss tangent, respectively, of the cap layer at 30°C, and E*b and tan δb are the complex modulus and the loss tangent, respectively, of the base layer at 30°C.