Runflat Tire Bead Reinforcer and Soft Rubber Compound
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Solution Overview
Problem
Runflat tires lack improved driving performance, handling, and comfort properties due to their stiff internal construction and limited ability to reduce rolling resistance and noise.
Innovation Solution
A pneumatic vehicle tire design featuring a carcass with metal cord reinforcers internally positioned within the bead filler, which extends beyond the reinforcer's end, and a soft rubber compound bead filler with an IHRD hardness lower than 80, enhancing torsional stiffness and comfort by direct force transmission and improved dampening properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stiff internal construction is used to provide self-supporting capability, then runflat performance is improved, but comfort properties and noise reduction deteriorate
Solution Approach 1:
The patent applies local quality by differentiating the hardness of rubber components at different locations. The bead filler uses soft rubber (IHRD < 80) at the bead portion for comfort, while the runflat reinforcement uses stiffer rubber (IHRD 80-95) at the sidewall for structural support. This localized variation in material properties resolves the contradiction between runflat performance and comfort.
Solution Approach 2:
The patent employs composite materials by combining metal cords with rubber compounds of different hardness levels. The reinforcer consists of metal cords embedded in soft rubber, while the runflat reinforcement combines metal cords with stiffer rubber. This composite approach allows simultaneous achievement of structural integrity and comfort properties.
2Strength
If metal cord reinforcers are positioned internally within the bead filler, then torsional stiffness and handling are improved, but risk of carcass damage by the reinforcer increases
Solution Approach 1:
The patent applies parameter changes by modifying the hardness parameter of the bead filler rubber to be softer (IHRD < 80) than conventional formulations. This softer rubber compound reduces the risk of the metal cord reinforcer damaging the carcass while maintaining adequate torsional stiffness through the metal cords themselves.
Solution Approach 2:
The soft rubber bead filler acts as an intermediary between the metal cord reinforcer and the carcass. This intermediate layer cushions and protects the carcass from potential damage by the rigid metal cords while still allowing effective force transmission for improved handling.
3Ease of operation
If a soft rubber compound bead filler is used to improve comfort, then dampening properties are improved, but structural stiffness may be reduced
Solution Approach 1:
The patent segments the tire structure into distinct functional zones with different rubber hardness levels. The bead portion uses soft rubber for comfort, while the sidewall runflat reinforcement uses stiffer rubber for structural support. This segmentation allows each zone to optimize its properties without compromising the other.
Solution Approach 2:
The patent applies local quality by assigning different rubber hardness properties to different locations: soft rubber (IHRD < 80) at the bead filler for comfort and noise reduction, and stiffer rubber (IHRD 80-95) at the runflat reinforcement for structural integrity. This spatial differentiation resolves the contradiction between comfort and stiffness.
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
The tire achieves higher runflat performance, reduced rolling resistance, and improved comfort and noise properties, with increased torsional stiffness and better handling due to the metal cord reinforcer and soft rubber bead filler combination.
Implementation Method 1
the bead filler is made of a soft rubber compound with an IHRD hardness lower than 80... the use of a soft compound for the bead filler effects better dampening properties which provide better comfort and noise properties
Implementation Method 2
Positioning of the reinforcer at the inner side of the bead provides a direct transmission of the forces from the carcass to the rim which further increases the torsional stiffness
Data Source
Figure 1~2
Figure 3~4
AI summary
A pneumatic vehicle tire comprises a carcass (11) extending between two bead cores (15). A belt structure (18) is provided between the carcass (11) and a tread strip (19) which is connected with a pair of sidewalls (20). A runflat reinforcement (17) is arranged at the inner side of each sidewall (20). A reinforcer (13) is arranged within each bead portion of the tire. A bead filler (14) extends from the bead ring (15) along the reinforcer (13). To improve the runflat performance, handling and comfort properties of such a runflat tire the reinforcer (13) is arranged at the inner side of the bead filler (14). The reinforcer (13) comprises metal cords. The bead filler (14) which extends beyond an end (13a) of the reinforcer (13) is made of a soft rubber compound with an IHRD hardness lower than (80), e.g. between (75) and (79).