Search Results

Combustion chamber deposits (CCD) in wall-guided stratified charged direct injection spark ignition (DISI) engines affect combustion significantly because CCD may disturb the air-fuel mixture formation and, as a result, cause emission deterioration. For the design of engines and fuels, it is therefore important to determine the effects of CCD on emissions from DISI engines. In this study, the effects of CCD on emissions from a DISI engine using different fuel distillation properties were investigated. The study results show that, during stratified charged operation, an increase in CCD increased the total hydrocarbon (THC) emissions under high speed conditions and the NOx emissions under the low speed conditions.

The effect of sulfur concentration in gasoline fuel on emissions from vehicles equipped with lean NOx catalyst (LNC) was studied. The durability of the emission control systems against sulfur poisoning was evaluated using three recently launched vehicles under mileage accumulation tests. The major elements for the NOx trap function of the lean NOx catalysts evaluated in this study were Ba, Na and/or K. The range of sulfur contents of the test fuels was 3 to 80 ppm. The mileage accumulation was conducted up to 10,000 km mainly with Japanese 11 lap mileage accumulation driving cycle where the average and maximum velocities are 46 and 100 km/h respectively. The effects of vehicle velocity on emissions were also investigated by modifying the mileage accumulation driving cycle. As a result, it was found that the durability of the emission control systems against sulfur poisoning has been remarkably improved with the recently launched vehicles.

The effects of injector deposits, combustion chamber deposits (CCD), and intake valve deposits (IVD) on exhaust emissions, fuel economy and engine performance have long been recognized in engine and fuel/detergent design. Because important elements of the engine design such as injector position, exhaust gas recirculation (EGR) ratio, and air fuel ratio (AFR) differ from those in port fuel injection (PFI) engines, direct injection spark-ignition (DISI) engines require specific evaluation methods. However, little data is available regarding engine deposits in the more recently produced DISI engines.

Evaporative emissions of Japanese older and current vehicles (1990-1998MY) and U.S. current vehicles, which were adapted to federal regulations in 1996, were investigated using typical Japanese gasoline. Japanese older and current vehicles exhibited high levels of Running Loss (RL), Hot Soak Loss (HSL) and Diurnal Breathing Loss (DBL), and their emissions showed strong Reid vapor pressure (RVP) dependence. On the other hand, U.S. vehicles showed very weak RVP dependence, between 62kPa and 76kPa. Their emissions also showed very low levels of RL, HSL and DBL. These results suggest RVP reduction is just effective for Japanese older and current vehicles. Evaporative emissions of Japanese and U.S. vehicles were also tested according to a new Japanese test procedure and the 35 degrees centigrade RL test procedure. In the case of the RL and DBL tests, the impact of test conditions on evaporative emissions was discussed as well.

We have developed a new semi-active suspension, called Piezo TEMS, that uses piezoelectric ceramic for suspension control with sensor and actuator. It improves remarkably driveability with the firm damping force mode and enhances the ride comfort with the soft damping force mode immediately after the road surface input exceeding the threshold level.