Research into Running Resistance Correction Technology Focused on Tire Temperature and a Tire Heat Balance Model 2019-01-0623
Basic practice is currently to measure running resistance outdoors, so the weather environment at the time of the testing has a great impact on the data. Laws enacted by individual countries about the influences of the natural environment stipulate the testing environment at the time of measurement, and correction methods have been set.
Running resistance is divided between rolling resistance and aerodynamic drag, and both are corrected to standard temperature (20°C), using the air temperature at the time of measurement, under the current regulation correction. This kind of correction by air temperature alone may be unable to correctly reflect current rolling resistance. We recognize the following two issues: One is that, compared to conventional tires, the rolling resistance of low fuel consumption tires of recent years is more highly dependent on temperature. The other is the factor of tire temperature variation relative to air temperature at the time of measurement.
This paper focuses on factors such as tire temperature properties, and has established correction technology by using a special rolling tester. Specifically, we used a tire rolling tester with a variable temperature environment, and we also assigned levels to other non-temperature factors (load, internal pressure, speed) which influence rolling resistance. Next, we used regression analysis on the data for each factor, to calculate the coefficients of the relational expression, and so derive the correction formula for tire rolling resistance as a quadratic equation. We were able to confirm that using this correction formula reduces variation, compared to the regulation correction.
Also, in order to perform the same kind of correction by a simpler method, we devised a technique to correct for the material properties of conventional rolling testers and tread rubber. We also report the results of considering further extension of this method to the conventional tire heat balance model.