Toyo delves into aerodynamics, noise with new technologies

Hyogo, Japan — Toyo Tire & Rubber Co. Ltd. has disclosed the development of technologies designed to reduce a tire's aerodynamic drag and to cut tire cavity noise significantly.

The first technology, which Toyo is calling "Mobility Aerodynamics," uses aerodynamic flow simulations to allow the company to predict the aerodynamic characteristics of tires and vehicles under rolling tire contact patch conditions.

Toyo claims using mobility aerodynamics will give it an advantage with vehicle makers in being able to propose ideas that could result in improved fuel consumption and extended range.

The breakthrough also should lead to the development of tires that have "excellent aerodynamic characteristics," based on high-precision simulations yielding numerical data consistent with the results of wind tunnel tests using actual vehicles.

Among the variables that have to be considered in measuring a tire's aerodynamic drag are individual tread patterns combined with simulations of actual vehicles and wheels, Toyo said. Tire deformation caused by differences in applied load, speed, running attitude angle and other factors were considered in order to develop techniques for aerodynamic characteristic simulations.

Toyo noted that reducing the negative effect of aerodynamic resistance pays dividends in improving fuel efficiency in vehicles with internal combustion engines and in extending the per-charge range in electric and/or hybrid vehicles.

As they rotate, tires on a moving vehicle keep deforming their shape while supporting the load. A rotating object has an effect on the air around it, changing the flow fields, Toyo said, estimating tires represent about 15% of the total air resistance experienced by a moving vehicle.

Optimising a cross-sectional contour of a tire profile, Toyo said, will improve aerodynamics and thus reduce fuel consumption.

Toyo also noted that its research into aerodynamics takes on added significance in light of technical rules adopted in 2014 by the United Nations' World Forum for Harmonization of Vehicle Regulations (WP29) for "measuring passenger vehicle fuel consumption and emissions."

This move standardised the measurement and testing procedures for automotive fuel consumption, emissions regulations and safety, Toyo said, which had until then differed by country or region. The testing procedures mandate resistance assessments of individual motor vehicles, includes wind tunnel tests to determine tire air resistance as well.

On the noise front, Toyo has developed a device that it claims reduces tire cavity noise — the type of noise that can transmit into a vehicle's interior — by as much as 12 dB in the critical frequency range of 200 to 250 Hz.

The new device, based on the company's "Toyo Silent Technology," comprises an arch-shaped ring of porous film attached to the tire innerliner by hollow foam cylinders at 16 points around the tire circumference.

As opposed to other solutions already in use that seek to absorb sound through the use of a porous foam attached the innerliner, Toyo is focusing its efforts on manipulating the air flow generated inside a tire as it rolls.

Toyo's technology works on the principle that noise is reduced when it passes through a pore, which involves two attenuation mechanisms — friction generated at the wall faces of the pore that the air passes through, and a vortex generated by the sound passing through the pore.

Using the flow of air when sound passes through the hole further increases the noise-reduction effect, Toyo said, so the porous film is positioned to face the flow of air (the pathway of the air) that the firm has ascertained from visualisation.