Pneumatic Tire Bead Second Apex Deformation Distribution
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Solution Overview
Problem
Conventional pneumatic tires face challenges in maintaining durability while avoiding increased rolling resistance and noise, which affects steering stability and fuel efficiency, due to the concentration of deformation on the turn-up portion and the impact of rigidity enhancements on the bead portion.
Innovation Solution
The tire design features a carcass ply turned up around the core, with a second apex positioned between the clinch and the turn-up portion, and a strip extending from the bead along the carcass, both made of crosslinked rubber with specific elastic moduli and tangents, to distribute deformation and enhance planar torsional rigidity without compromising steering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the carcass ply is turned up around the core from the axially inner side toward the outer side to fix the bead portion, then the bead portion is securely fixed onto the rim, but deformation concentrates on the turn-up portion which reduces durability
Solution Approach 1:
The patent applies local quality by positioning the second apex specifically at the turn-up portion of the carcass ply, where deformation concentration occurs. This localized reinforcement targets the critical area needing support without altering the overall carcass structure, thereby maintaining bead fixation reliability while improving durability at the vulnerable turn-up portion.
Solution Approach 2:
The patent uses composite materials by combining the second apex (made of rubber composition with specific physical properties including complex elastic modulus of 60-70 MPa) with the existing carcass ply structure. This composite construction provides enhanced mechanical support at the turn-up portion, distributing deformation more effectively and preventing the concentration that leads to durability issues.
2Stability of the object's composition
If rigidity is enhanced at the bead portion to improve steering stability, then steering stability is improved, but rolling resistance increases which reduces fuel efficiency
Solution Approach 1:
The patent applies local quality by providing the second apex specifically at the turn-up portion rather than uniformly throughout the bead structure. This localized approach enhances planar torsional rigidity where needed for steering stability while avoiding excessive rigidity in other areas that would increase rolling resistance and reduce fuel efficiency.
Solution Approach 2:
The patent uses parameter changes by carefully controlling the complex elastic modulus of the second apex within the range of 60-70 MPa. This specific parameter range provides sufficient rigidity enhancement for steering stability while preventing excessive stiffness that would lead to increased rolling resistance and reduced fuel efficiency.
3Duration of action of stationary object
If the second apex and strip are made of crosslinked rubber with specific elastic modulus to distribute deformation, then durability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies merging by integrating the second apex and strip as part of the existing carcass ply structure rather than treating them as completely separate components. The second apex is positioned at the turn-up portion and the strip extends along the carcass, creating a unified structure that simplifies manufacturing while providing the durability benefits of deformation distribution through the specifically formulated crosslinked rubber with complex elastic modulus of 60-70 MPa.
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
This design achieves enhanced durability and reduced rolling resistance, maintaining steering stability and improving fuel efficiency by suppressing deformation concentration and heat generation, while minimizing noise and mass.
Implementation Method 1
the second apex includes a crosslinked rubber and has a complex elastic modulus in a range of from 60 MPa to 70 MPa
Data Source
AI summary
A pneumatic tire includes a tread, sidewalls, clinches, beads, a carcass, and strips. Each bead includes a core, a first apex and a second apex, the carcass includes a carcass ply which is turned up around the core from the axially inner side toward outer side such that the carcass ply is divided into a main portion and a turn-up portion, each strip has radially inner edge positioned between the main and turn-up portions, the second apex is positioned between the turn-up portion and each clinch, each strip has outer edge positioned to correspond to or on inner side of a point of maximum width of the tire in radial direction, the second apex has outer edge positioned on radially inner side of the outer edge of each strip, and the second apex includes crosslinked rubber and has complex elastic modulus in range of from 60 MPa to 70 MPa.