Pneumatic Tire Inner Rubber Layout for EV Noise Reduction
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Solution Overview
Problem
Pneumatic tires in hybrid and electric vehicles face challenges in reducing both vehicle exterior and interior noise due to reduced noise from the vehicle body during travel.
Innovation Solution
A pneumatic tire design with a tread portion having a land ratio of 65% or more, featuring a first inner rubber portion with a larger thickness than a second portion, and specific loss tangent values to enhance vibration absorption and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the land ratio of the tread portion is increased to reduce vehicle exterior noise, then vehicle exterior noise is reduced, but the tire structure becomes more complex
Solution Approach 1:
The patent applies local quality by creating a first portion of the inner rubber with different thickness and loss tangent properties than the second portion. The first portion (extending through the tread) has a larger thickness and specific loss tangent range to provide localized vibration absorption at the tread-carcass interface, while the second portion (extending through the sidewalls) has different properties optimized for sidewall performance. This localized differentiation allows noise reduction through optimized damping characteristics without requiring complete structural redesign of the entire tire.
Solution Approach 2:
The patent utilizes parameter changes by specifying particular ranges for the loss tangent of the first portion (tan δ1 at 70°C not less than tan δ2 of the second portion and not more than tan δA of the tread rubber at 30°C) and the thickness ratio between the first and second portions. These parameter specifications optimize the viscoelastic damping characteristics of the inner rubber to absorb vibrations generated by the high land ratio tread pattern, thereby reducing vehicle exterior noise while maintaining manageable structural complexity.
2Object-generated harmful factors
If the first thickness of the inner rubber is increased to improve vibration absorption, then noise reduction is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies parameter ranges rather than fixed values for the first thickness and loss tangent of the first portion. The loss tangent is constrained within a specific range (not less than tan δ2 of the second portion and not more than tan δA of the tread rubber at 30°C), which provides manufacturing flexibility while ensuring effective vibration absorption. This range-based specification approach balances noise reduction performance with manufacturability, avoiding overly stringent precision requirements.
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 effectively reduces both vehicle exterior and interior noise while maintaining steering stability and fuel efficiency.
Implementation Method 1
the loss tangent tan δ1 of the first portion at 70 degrees c is not less than the loss tangent tan δ2 of the second portion at 70 degrees C and not more than the loss tangent tan δA of the tread rubber at 30 degrees C
Implementation Method 2
the pneumatic tire capable of reducing both vehicle exterior noise and vehicle interior noise
Data Source
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AI summary
A pneumatic tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions, a carcass extending between the portions, and an inner rubber extending between the portions, on the inner side of the carcass. The inner rubber comprises a first portion extending through the tread portion with a first thickness and a second portion extending through the sidewall portions with a second thickness smaller than the first thickness. The land ratio of the tread portion 2 is 65% or more.