Two-Layer Tread Cap with Differential Modulus for Tire Balance
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Solution Overview
Problem
Pneumatic vehicle tires face a challenge in balancing low rolling resistance and good snow performance, as existing designs often compromise on one property to improve the other, making it difficult to achieve both simultaneously.
Innovation Solution
The tire features a two-layer tread cap with radially outer and inner cap layers having matching Shore A hardness but differing dynamic storage moduli at specific temperatures, with the inner cap layer having a higher modulus at 55°C and the outer cap layer having a lower modulus at -15°C, optimizing handling, rolling resistance, and snow performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tread is designed with a single layer or conventional multi-layer structure, then manufacturing is simpler, but it is difficult to achieve both low rolling resistance and good snow performance simultaneously
Solution Approach 1:
The tread cap is segmented into two distinct cap layers (first and second cap layers) with different rubber compound formulations. The first cap layer has a first dynamic storage modulus and the second cap layer has a second dynamic storage modulus, creating a differentiated structure that addresses both snow performance and rolling resistance requirements in different radial zones of the tread.
Solution Approach 2:
Different regions of the tread cap are assigned different material properties. The first cap layer (typically the tread shoulder area) has properties optimized for snow traction, while the second cap layer (typically the tread center area) has properties optimized for low rolling resistance. This local differentiation allows each region to perform its specific function optimally.
2Reliability
If the tread layers are designed with different Shore A hardnesses, then traction properties improve, but handling properties and even wear deteriorate
Solution Approach 1:
Instead of varying Shore A hardness, the invention changes the dynamic storage modulus parameter at specific temperatures (60°C and -30°C) to differentiate the cap layers. The first cap layer has a higher dynamic storage modulus at -30°C for snow traction, while the second cap layer has a higher dynamic storage modulus at 60°C for handling and wear resistance, achieving both goals without compromising either.
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
This design enhances handling properties, reduces rolling resistance, and improves traction and braking on snow and slush, while maintaining good aquaplaning properties, by adjusting the dynamic storage moduli of the cap layers to match specific temperature conditions.
Implementation Method 1
the radially inner cap layer has a larger dynamic storage modulus at 55 °C than the radially outer cap layer, the dynamic storage modulus being a dynamic storage modulus averaged over the strain from a dynamic-mechanical measurement with a strain run at a Precompression of 20% in the expansion range of 0.15% to 8% and a frequency of 10 Hz at a temperature of 55 °C
Implementation Method 2
the radially outer cap layer has a smaller dynamic storage modulus at -15 °C than the radially inner cap layer
Implementation Method 3
the two cap layers having matching Shore A hardnesses, determined according to DIN ISO 7619-1
Data Source
Figure 1
AI summary
The invention relates to a pneumatic vehicle tire of radial design with a tread (1) having a profiled two-layered tread cap (3) with a radially outer cap layer (3a) and a radially inner cap layer (3b). The radially inner cap layer (3b) has a higher dynamic storage modulus at 55°C, measured based on DIN 53512, than the radially outer cap layer (3a), the two cap layers (3a, 3b) having identical Shore A hardnesses, measured according to DIN ISO 7619-1.