Search Results

This paper describes a longitudinal control method with an Adaptive Cruise Control (ACC) system using a wheel torque management technique. The wheel torque management technique can control vehicular speed by the following procedure without tuning parameters. First, the ACC module calculates a command speed from a desired headway distance and from output data of the radar sensor. Secondly, it calculates a required wheel torque to take the command speed, current speed and running resistance into consideration. Thirdly, the management module controls actuators based on the command wheel torque and characteristics of each vehicle. If the required wheel torque is positive, the management module orders adjustment of the throttle opening position and a change of the gear ratio in the automatic transmission. If the command wheel torque is negative, the management module activates the electronic brake in accordance with the magnitude of the command wheel torque.

It has been hitherto recognized merely by experience that the power output of a two-stroke cycle crankcase compression gasoline engine is inversely proportional to a power exponent larger than 0.5 of the absolute atmospheric temperature. To ascertain this effect, a 60 cm3 two-stroke cycle crankcase compression gasoline engine was performance tested at various inlet air temperatures. It was found that the power output varied inversely proportional to a power exponent ranging from 0.5 to 0.9 of the absolute inlet air temperature. This was explainable by the fact that the pressure ratio of the crankcase decreased as the air temperature increased and vice versa.

In order to study the potentiality of the modification of the combustion rate for NOx formation control in the spark ignition (SI) engine, the authors first developed a new mathematical model by assuming the stepped gas temperature gradient in the cylinder. The predicted results from this new mathematical model show good coincidence with the experimental data. Second, the authors discuss the effects of the modification of the combustion rate on NOx formation using the new mathematical model. It was concluded that NOx formation in the premixed SI engine would be essentially determined by the specific fuel consumption only, regardless of any modification of the engine combustion rate.

Three Japanese automobile manufacturers-Mitsubishi Motors Corp., Nissan Motor Co., Ltd., and Toyo Kogyo Co., Ltd.-have been making efforts over the past three years to design and develop effective thermal reactor-exhaust gas recirculation and catalytic converter systems suitable for small engines. The work is being done by members participating in the IIEC (Inter-Industry Emission Control) Program, and the exhaust emission levels of the concept vehicles developed by these companies have met the goal established by the IIEC Program at low mileage. Each system, however, has a characteristic relationship between exhaust emission level and loss of fuel economy. Much investigation is required, particularly with respect to durability, before any system that will fully satisfy all service requirements can be completed. This paper reports the progress of research and development of the individual concept vehicles.

As the demand for improved fuel economy increases and new CO2 regulations have been issued, aerodynamic drag reduction has become more critical. One of the important factors to consider is cooling drag. One way to reduce cooling drag is to decrease the air flow volume through the front grille, but this has an undesirable impact on cooling performance as well as component heat load in the under-hood area. For this reason, cooling drag reduction methods while keeping reliability, cooling performance and component heat management were investigated in this study. At first, air flow volume reduction at high speed was studied, where aerodynamic drag has the greatest influence. For vehicles sold in the USA, cooling specification tends to be determined based on low speed, while towing or driving up mountain roads, and therefore, there may be extra cooling capacity under high speed conditions.

Suppression of NH3 formation over NOx catalysts has been the subject of several reports in recent years. However, there are very few reports relating to the effects of modifications of both feed gas conditions and catalyst usage. Therefore, NH3 formation was investigated as a function of such feed gas boundary conditions as CO concentration, CO/O2 ratio, space velocity, linear velocity and catalyst bed temperature. Both fresh and aged NOx catalysts were used. Longitudinal patterns of NH3 formation in monolithic NOx catalyst were also determined. Based on these results, several ideas were tested to reduce NH3 formation in the NOx catalyst through control of feed H2, O2, CO and HC concentrations. Finally, the possibility of extending the optimum A/F range of a NOx catalyst toward leaner A/F ratios by the introduction of methane ahead of the NOx catalyst is discussed.