Pneumatic Tyre Belt Layers Inversion for Tread Protection
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Solution Overview
Problem
Pneumatic vehicle tires with a belt package featuring crossing steel reinforcement plies face challenges in damage and puncture resistance in the tread area, as the radially inner, stronger ply can overwhelm the radially outer, weaker ply, compromising traction and driving dynamics in vehicles other than motorcycles.
Innovation Solution
The use of steel monofilaments for the radially inner working ply and steel cords for the radially outer working ply, with the latter having higher breaking strength and energy, acts as a protective shield while ensuring adequate force transmission and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the radially inner working ply is made firmer with higher extensional stiffness to improve wear and traction properties, then abrasion resistance and traction are improved, but damage and puncture resistance in the tread area deteriorates because the radially outer working ply becomes insufficient to resist external damage
Solution Approach 1:
The patent applies parameter changes by inverting the traditional strength distribution in the belt package. Instead of having the radially inner ply stronger than the radially outer ply (conventional approach), the patent makes the radially outer working ply stronger with higher breaking strength and/or breaking energy than the radially inner working ply. This parameter inversion resolves the contradiction by allowing the outer ply to serve as a protective shield against damage and puncture while the inner ply maintains adequate force transmission capabilities for traction and driving dynamics
Solution Approach 2:
The patent implements inversion by reversing the conventional strength hierarchy between the two working plies. Traditionally, the inner ply is designed to be stronger to handle driving forces, but the patent inverts this arrangement by making the outer ply stronger to prioritize damage and puncture resistance. This inversion allows the outer ply to act as a protective barrier while the inner ply, though weaker, still suffices for force transmission to the road
2Ease of operation
If the radially outer working ply is made weaker to allow the radially inner ply to dominate force transmission, then traction and driving dynamics are maintained, but damage and puncture resistance in the tread area deteriorates
Solution Approach 1:
The patent changes the strength parameters of the working plies by making the radially outer ply stronger than the radially inner ply in terms of breaking strength and/or breaking energy. This parameter change resolves the contradiction by reassigning the primary protective function to the outer ply while the inner ply maintains sufficient strength for force transmission, thereby improving both reliability and ease of operation simultaneously
Solution Approach 2:
The patent applies inversion by reversing the conventional role assignment between the two working plies. Instead of the inner ply being the stronger protective layer, the patent makes the outer ply stronger to serve as the primary shield against damage and puncture. This inversion allows the outer ply to protect the tire structure while the inner ply handles force transmission, resolving the contradiction between reliability and ease of operation
Data Source
AI summary
The tire has a belt package (8) comprising two working layers i.e. belt plies (8a, 8b), which consist of parallel and mutually spaced strength carriers embedded in rubber material. One of the working layers is arranged radially inside with respect to the other working layer, where the strength carriers of the former working layer are arranged transverse to the strength carriers of the other working layer. The strength carriers of the latter working layer comprise high tensile strength and/or high rupture energy than that of the former working layer. The strength carriers made from steel.