Heavy Duty Tire Belt Width and Twist Optimization
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Solution Overview
Problem
Conventional pneumatic radial tires for heavy load vehicles face limitations in durability, particularly under high-speed and high-load conditions, with insufficient heat durability and cut resistance, especially for vehicles operating on rough roads with increased tire sizes.
Innovation Solution
A pneumatic radial tire design featuring a radial carcass ply with at least six belt layers, where specific width and cord diameter ratios are maintained, and steel cords with a double twist structure and controlled twist angles to enhance hoop effect, stiffness, and cut protection without compromising heat durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques are used to improve tire durability under high-speed and high-load conditions, then tire size increases, but heat durability and cut resistance reach a limit
Solution Approach 1:
The patent changes the geometric parameters of the belt structure by defining specific width ratios (W12/W34 between 0.8-1.2 and W34/W56 between 0.8-1.2) and cord diameter ratios (D12/D34 between 0.8-1.2), optimizing the distribution of stress and heat across different belt layers to improve durability without increasing overall tire size
Solution Approach 2:
The patent employs a composite belt structure with at least six belt layers having different cord arrangements and material compositions, combining layers with cords at different angles (θ1 and θ2) to simultaneously achieve heat resistance, cut penetration resistance, and structural stiffness
2Reliability
If multiple belt layers are added to improve cut protection and hoop effect, then belt structure complexity increases, but manufacturing and design become more difficult
Solution Approach 1:
The patent establishes specific parameter ranges for the six belt layers including width ratios (W12/W34 and W34/W56 between 0.8-1.2) and cord diameter ratios (D12/D34 between 0.8-1.2), which standardizes the design process and makes complex multi-layer structures more manageable through quantitative constraints
Solution Approach 2:
Different belt layers are designed with locally optimized properties: inner layers (1st-2nd) have specific cord arrangements for cut protection, middle layers (3rd-4th) provide hoop effect, and outer layers (5th-6th) enhance stiffness, with each layer's cord diameter and width specifically tailored to its functional requirement
3Strength
If cord arrangement angle is reduced to improve stiffness in circumferential direction, then heat durability may be compromised
Solution Approach 1:
The patent optimizes the cord arrangement angles θ1 and θ2 within specific ranges to balance stiffness and heat durability, and defines the ratio relationship (0.4 < θ2/θ1 < 2.0) to ensure that reducing angle for stiffness does not excessively compromise heat dissipation capabilities
Solution Approach 2:
The multi-layer belt structure with different cord angles creates a composite system where layers with smaller angles provide circumferential stiffness while layers with larger angles facilitate heat dissipation, achieving both requirements through material layering
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 durability, including enhanced cut penetration resistance and reduced heat generation in the belt edges, maintaining original stiffness and separation performance.
Implementation Method 1
a steel cord of each belt layer has a double twist structure in which a plurality of steel filaments are twisted to form a cable and two to ten cables are further twisted
Implementation Method 2
the small-inclination belt layers bears the tension of the tread in the circumferential direction to restrain radial expansion of the tread
Implementation Method 3
the main intersecting belt layers assure stiffness (lateral stiffness, in-plan bending stiffness and the like) against deformation along the plane of the belt
Data Source
Figure 1
Figure 2~3
AI summary
There are provided a pneumatic radial tire of heavy load vehicles, in which durability of a belt is improved. A pneumatic radial tire for heavy load vehicles comprises a pair of bead portions in each of which a bead core is embedded, a radial carcass ply 1 extending from one bead portion to the other bead portion and turned around the bead core from an inner side to an outer side of the bead core in a width direction of the tire and at least six belt layers 2 disposed on an outer side of this radial carcass ply 1 in a radial direction of the tire, wherein the following relations are satisfied: W56 > W34 > W12, where W12 is a maximum width of first and second belts 2a f the belt layers 2, W34 is a maximum width of third and forth belts 2b of the belt layers 2 and W56 is a maximum width of fifth and sixth belts 2c of the belt layers 2; and 1 > D12/D34 > 0.6, where D12 is a cord diameter of the first and second belts and D34 is a cord diameter of the third and forth belts. In addition, a steel cord of each belt layer has a double twist structure in which a plurality of steel filaments are twisted to form a cable and two to ten cables are further twisted.