Pneumatic Tire Inner Liner Lap-Splice Thinning
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Solution Overview
Problem
Pneumatic tires with inner liners made of thermoplastic resin films experience delamination issues at the lap-splice portions due to stress and cracking, leading to reduced durability during use.
Innovation Solution
The tire design incorporates a lap-splice portion where the thermoplastic resin film is thinned over part or all of the tire width before the splice, with a circumferential overlap length of 3 to 30 mm and a thin film thickness of 20% to 80% of the standard thickness, reducing stress and preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thermoplastic resin film is thinned at the lap-splice portion, then stress concentration and delamination are reduced, but the air permeation resistance may be compromised
Solution Approach 1:
The patent applies local quality by thinning the film only at the lap-splice portion where stress concentration occurs, while maintaining the original thickness in other areas. This localized modification reduces delamination risk at the splice without compromising the overall air permeation resistance of the inner liner.
Solution Approach 2:
The patent changes the physical parameter of film thickness specifically at the lap-splice portion, reducing it from the standard thickness to a thinner gauge. This parameter change allows the splice area to better accommodate stress and deformation, preventing delamination while the rest of the film maintains its protective properties.
2Reliability
If the film thickness is reduced to 20%-80% of standard thickness at the lap-splice portion, then crack development is prevented, but the structural strength at that location is reduced
Solution Approach 1:
The patent applies local quality by reducing film thickness only at the lap-splice portion where cracks typically initiate, while maintaining full thickness elsewhere. This localized thinning prevents crack development at the stress-prone splice area without significantly compromising the overall structural strength of the inner liner.
Solution Approach 2:
The patent applies beforehand cushioning by pre-thinning the film at the lap-splice portion before the tire is put into service. This proactive modification creates a stress-relief zone that cushions against future crack initiation and propagation during tire operation.
3Strength
If the lap-splice overlap length is increased to 3-30 mm, then the splice strength is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the lap-splice overlap length to a specific range of 3-30 mm. This parameter optimization ensures sufficient splice strength to prevent delamination while avoiding excessive overlap that would complicate the manufacturing process and increase material consumption.
Data Source
AI summary
A pneumatic tire in which an inner liner including a film mainly made of thermoplastic resin is attached to an inside of the tire via a tie rubber sheet, on an inner side of a carcass layer, and which has a lap-splice portion where end portions of the film in a tire circumferential direction overlap each other in a tire widthwise direction with tie rubber therebetween. A section of the film on a tire cavity side in the lap-splice portion has a portion where the film is thin over part or entirety of the width in the tire widthwise direction before the lap-splice portion, or a film thickness in the lap-splice portion is smaller than a film thickness in a portion other than the lap-splice portion. Thus, the pneumatic tire has no crack developing around the lap-splice portion of an inner liner layer after running, and has excellent durability.