Pneumatic Tire Bead Apex Rubber Geometry for Lateral Rigidity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pneumatic tire designs face challenges in maintaining steering stability while avoiding increased mass, as they often require wider clip widths in vulcanization molds, leading to non-uniform tension and reduced lateral rigidity, which can be mitigated by optimizing the carcass profile and bead apex rubber geometry.
Innovation Solution
A pneumatic tire design featuring a carcass ply with angled bead apex rubbers and specific geometric ratios to achieve a natural equilibrium shape under standard inflation, combined with a manufacturing method that adjusts bead width and tire profile to enhance lateral rigidity without increasing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clip width of the tire vulcanization mold is made wider than the standard rim width to ensure bead durability and rim assembling property, then the carcass profile becomes off natural equilibrium shape under standard inflation, resulting in non-uniform tension and reduced lateral rigidity
Solution Approach 1:
The invention applies preliminary action by pre-deforming the carcass profile during the vulcanization process using a mold with wider clip width. The carcass is intentionally formed with a specific deformed shape that will transform into the natural equilibrium shape after mounting on the rim, thereby eliminating the need to choose between wide clip width for durability and narrow clip width for profile equilibrium.
2Stability of the object's composition
If the clip width of the tire vulcanization mold is made equal to the standard rim width to achieve natural equilibrium carcass profile, then the bead portions are subject to compressive strain upon mounting, resulting in deterioration of bead durability and rim assembling property
Solution Approach 1:
The invention uses preliminary action by pre-forming the bead portions with increased radius of curvature during vulcanization in a mold with wider clip width. This preliminary deformation ensures that when the tire is mounted on the standard rim, the bead portions are not subjected to compressive strain, thereby maintaining both profile equilibrium and bead durability.
3Reliability
If the bead radius of curvature is increased to improve rim assembling property and reduce compressive strain on bead portions, then the lateral rigidity of the tire is reduced, deteriorating steering stability
Solution Approach 1:
The invention applies local quality by differentiating the radius of curvature values at different locations of the bead portions. The maximum radius of curvature is set at 3mm or more for improved rim assembling property, while the radius of curvature at the bead apex is specifically controlled at 1.5mm or less to maintain lateral rigidity. This localized differentiation resolves the contradiction between rim assembling property and lateral rigidity.
4Strength
If sidewall rubbers are thickened or reinforcing plies are added to compensate for reduced lateral rigidity, then the mass of the tire increases, deteriorating rolling resistance
Solution Approach 1:
The invention applies parameter changes by optimizing the geometric parameters of the carcass profile, specifically the ratios h/H and h2/H2, and the angle θ of the bead reference line. By adjusting these parameters within specific ranges, the invention achieves improved lateral rigidity and steering stability without increasing tire mass, thereby avoiding deterioration of rolling resistance.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A pneumatic tire includes a carcass includes at least one carcass ply of cords extending between bead cores of bead portions through a tread portion and sidewall portions, wherein both ends of the carcass ply are turned up around the respective bead cores, and a pair of bead apex rubbers each extending radially outwardly to a radially outer end from a radially inner surface that is connected to the respective bead cores. In a tire meridian cross-section under a standard inflated state, in each of the bead portions, an angle () of a bead reference line (N) that passes an axially center point of the inner surface (Pm) of the bead apex rubber and the radially outer end of the bead apex rubber is in a range of from 28 to 35 degrees with respect to a tire radial line (X).