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In recent years, the contribution of tires on vehicle fuel economy has been garnering attention. Up until now, rolling resistance coefficient (RRC) has been the standard way of measuring the amount of impact the tire has on fuel economy. We devised a new method for evaluating the impact of tires on fuel economy that incorporates the concept of tire “driving transmission efficiency” (hereinafter referred to as “driving stiffness”). In doing so, we have clarified the technology direction for contributing to the improvement of fuel economy while maintaining vehicle maneuverability by reducing RRC and improving tire driving stiffness.

Continuous measurement of dilute exhaust gas from the CVS system, which provides gas concentrations proportional to the mass of emissions, is widely used for modal mass analysis of exhaust emission. Recently, exhaust gas flow rate measurement devices have become commercially available. Cost-effective raw exhaust modal mass analysis will be feasible with a combination of the new exhaust gas flow meters and fast response gas analyzers. In this paper, the benefits of raw exhaust modal mass measurement and the impacts of response time for the gas analyzer on the accuracy of exhaust mass calculations are discussed. Gas analyzer system with enhanced speed of response has been developed by hardware modification applied to the existing conventional bench system. De-convolution or inverse digital filter techniques that compensate the delay in the exhaust sampling system and the gas analyzer are described with comparisons to the hardware modifications.

Numerous studies have been conducted on the effect of gasoline composition on automobile exhaust hydrocarbons, in order to improve the air quality and reduce the impact on the environment. However, the quantitative relationship between gasoline composition and exhaust hydrocarbon has not been clarified. The purpose of this study is to evaluate the characteristics of individual hydrocarbons in gasoline and to clarify the effect of the gasoline composition on engine-out exhaust hydrocarbons. Experiments were performed on a single cylinder research engine operating under steady state condition. The test fuels were blended gasolines of alkylate, catalytic reformate and fluid catalytic cracking gasoline. Chemically defined binary fuel mixtures of isooctane, benzene, toluene, xylene and ethylbenzene were used as variables to study their impact on exhaust hydrocarbons. The individual exhaust hydrocarbon species were analyzed using a gas chromatograph with flame ionization detector (FID).

Improving the automobile fuel economy, it is necessary to measure the power loss of the drive train with high accuracy. The authors propose a new method for measuring the friction loss of automobile drive train. This method is based on the measurement of temperature rise of lubricant due to the friction in a drive train, and allows us to separate the friction loss into the lubricant churning loss and the gear friction loss. Applying the new method to a manual transmission and a rear axle, the friction loss of automobile drive train was measured with much higher accuracy, and effects of the gear ratio, input shaft speed, lubricant temperature, kinematic viscosity and differences of drive train on the friction loss have been revealed.