Pneumatic Tire Groove Cracking Prevention via Carcass Curvature Optimization
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Solution Overview
Problem
Heavy-duty pneumatic tires with low profiles experience groove cracking due to strain in the main groove bottom, which is difficult to prevent with conventional designs that struggle to maintain consistent curvature radii and shape variations during inflation.
Innovation Solution
A pneumatic tire design with a toroidal carcass layer and optimized belt layer arrangement, where specific geometric relationships between tire dimensions and curvature radii are maintained to reduce shape changes and strain in the main groove, thereby preventing groove cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-profile heavy-duty pneumatic tire is designed with conventional carcass line curvature, then the tire can be manufactured with standard geometry, but groove cracking occurs in the outer circumferential main groove due to excessive strain during inflation
Solution Approach 1:
The patent applies local quality by creating different curvature radius characteristics in different regions of the carcass line. Specifically, the outer circumferential side portion has a larger curvature radius than the inner circumferential side portion, optimizing each region's strain characteristics during inflation to prevent groove cracking while maintaining overall tire performance
Solution Approach 2:
The patent changes the geometric parameters of the carcass line by defining specific curvature radius relationships (Ra/Rb ratio between 1.05-1.30) and position ratios (e.g., distance from tread surface to inflection point). These parameter changes optimize the strain distribution in the groove bottom during inflation, preventing groove cracking
2Reliability
If the carcass line curvature radius is increased on the outer circumferential side to reduce groove strain, then groove cracking resistance improves, but the tire shape changes excessively during inflation
Solution Approach 1:
The patent introduces an inflection point in the carcass line on the outer circumferential side, creating distinct curvature zones. This local structural modification allows the outer groove region to maintain better shape stability during inflation while still reducing strain through the optimized curvature radius ratio, thus preventing groove cracking without excessive overall shape change
3Shape
If the tire profile is reduced to achieve low-profile design, then the tire has better handling and aesthetics, but the groove bottom becomes more susceptible to cracking under load
Solution Approach 1:
The patent changes the carcass line geometry parameters specifically for low-profile tires by defining curvature radius ratios (Ra/Rb = 1.05-1.30) and position relationships (e.g., inflection point distance from tread surface). These parameter optimizations compensate for the reduced profile height, maintaining groove cracking resistance despite the lower tire profile
Solution Approach 2:
The patent applies curvature optimization by carefully designing the carcass line's curvature radius variation along the tire profile. The optimized curvature distribution in the low-profile design reduces stress concentration in the groove bottom while maintaining the compact profile shape, preventing cracking under load
Data Source
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AI summary
In a cross section of a pneumatic tire 1 in a tire meridian direction when the pneumatic tire 1 is held alone to have a tire base width equal to or more than 100[%] and equal to or less than 120[%] of a width of an applied rim, a geometric profile of the pneumatic tire 1 satisfies 48[%]≤HB/HA≤52[%], 98[%]≤HC/HA≤100[%], 108[%]≤WB/WA≤115[%], and 55[%]≤WC/WA≤75[%], where WA is distance of a half of the tire base width, WB is distance from a Y-axis to a maximum width position P of a carcass layer 3, WC is distance from the Y-axis to an inflection point Q of the carcass layer 3, HA is distance from an X-axis to a peak R of the carcass layer 3 on the center crown CL, HB is distance from the X-axis to the maximum width position P of the carcass layer 3, and HC is distance from the X-axis to the inflection point Q of the carcass layer 3.