Pneumatic Tire Carcass Profile Design for Rolling Resistance
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Solution Overview
Problem
The existing design methods for pneumatic tires increase the number of steps in the design process with each tire width variation, leading to increased load and potential distortion, which can reduce durability and increase rolling resistance.
Innovation Solution
A method for determining a carcass profile using the natural equilibrium shape theory, which allows for quick determination of carcass profiles across multiple tire widths, incorporating specific points and mathematical expressions to optimize the tire's shape and reduce rolling resistance without affecting mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the carcass profile is designed for each tire width using conventional methods, then the tire can accommodate multiple sizes, but the number of design steps increases and the designing load increases
Solution Approach 1:
The patent establishes a universal design method where a single master carcass profile serves as the basis for generating multiple tire width variants. The master profile contains fundamental geometric parameters that can be scaled and adjusted to create different tire sizes while maintaining consistent structural characteristics, thereby reducing the need for separate design processes for each tire width.
Solution Approach 2:
The patent utilizes parameter-based design where the master carcass profile is defined by a set of control parameters. By changing specific parameters (such as scaling factors and offset values), the same master profile can generate multiple tire width variations. This approach transforms the design process from creating multiple unique profiles to adjusting parameters of a single master profile.
2Adaptability or versatility
If the carcass profile is designed for each tire width, then different tire sizes can be produced, but variation in designing occurs and excess distortion is generated in rubber and cords
Solution Approach 1:
The master carcass profile serves as a standardized template that ensures consistency across all tire width variants. By deriving all variants from this single master profile, the patent eliminates variation in designing that occurs when each tire width is designed independently, thereby maintaining uniform manufacturing precision across different tire sizes.
Solution Approach 2:
The master carcass profile is designed in advance with optimal geometric characteristics that minimize distortion. This preliminary design establishes the fundamental shape and curvature that are then replicated across different tire widths, preventing excess distortion in rubber and cords before the actual tire manufacturing process begins.
3Ease of manufacture
If the carcass profile deviates from the natural equilibrium shape, then the tire can be manufactured with simpler processes, but durability is reduced due to concentration of stress or distortion
Solution Approach 1:
The patent defines specific parameter ranges for the master carcass profile that ensure the natural equilibrium shape is maintained. By controlling parameters such as curvature radius, profile curvature, and geometric ratios within predetermined ranges, the patent achieves both manufacturing simplicity and enhanced durability, eliminating the need to choose between the two opposing requirements.
Solution Approach 2:
The patent incorporates verification steps where the designed master carcass profile is checked against the natural equilibrium shape criteria. This feedback mechanism ensures that the profile maintains the optimal balance between manufacturing ease and structural integrity, preventing deviations that would compromise durability while preserving manufacturing simplicity.
4Adaptability or versatility
If multiple tire widths are designed independently, then each tire can be optimized for its specific size, but the load in the design process increases
Solution Approach 1:
The master carcass profile acts as a universal foundation that can generate multiple tire width variants through parameter adjustment. This approach allows the design process to cover a wide range of tire widths while maintaining a consistent methodology, thereby reducing the cumulative design load that would result from independently optimizing each tire size.
Solution Approach 2:
The patent segments the design process into two distinct stages: (1) creating the master carcass profile with fundamental geometric characteristics, and (2) generating specific tire width variants by adjusting parameters of the master profile. This segmentation reduces design load by separating the complex creative work from the repetitive adaptation work.
Data Source
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AI summary
[Object] A pneumatic tire 2 that allows achievement of reduction of rolling resistance without taking influence on a mass into consideration, is provided. [Solution] A profile OL of the tire 2 includes a ground-contact surface 46 and a pair of side surfaces 48. In the profile OL, a zone from a point PB to a point PW is formed by three arcs. The arcs are a first arc, a second arc that extends almost outward from the first arc in the radial direction, and a third arc that extends almost outward from the second arc further in the radial direction. A ratio of a radius R2 of curvature of the second arc to a radius R1 of curvature of the first arc is greater than or equal to 1.45 and not greater than 3.26. A ratio of a radius R3 of curvature of the third arc to the radius R1 of curvature of the first arc is greater than or equal to 0.45 and not greater than 0.56. Each sidewall 8 of the tire 2 has a first recess 50a and a second recess 50b that are recessed inward from the side surface 48.