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In this paper, the general effects of the regeneration parameters, such as initial particulate loading, space velocity, oxygen concentration and inlet gas temperature, on the combustion of the particulate matter (PM) filtrated in the ceramic filter of a diesel particulate filter (DPF) system are considered experimentally. A new method to control the combustion rate of the PM during regeneration is also studied for the protection of the ceramic cordierite filter. It controls the temperature of gas entrained into the filter during re-generation, which was previously not considered as a controllable factor in the vehicle[1, 2, 3, 4 and 5]. Control of gas temperature was achieved by controlling the flow rate of engine exhaust gas entrained into the filter during regeneration.

In order to reduce PM (Particulate Matter) emitted from diesel vehicles, we have been developing the particulate trap system using a burner since 1993. This AEFR system (Active Exhaust Feeding Regeneration System) shows considerably low peak temperatures and temperature gradients in the filter during the regeneration process. The AEFR system used the engine exhaust gas partially for the regeneration of the ceramic wall flow filter. It controlled the bypass flow rate of the engine exhaust gas actively for the combustion rate control of filtrated PM. The temperature distributions and temperature gradients in the filter during the regeneration process varied widely according to the regeneration control schemes. Scheme III has shown the most desirable peak temperatures and temperature gradients in the filter during the regeneration processes with AEFR system.

In order to estimate the air-fuel ratio of hydrogen fueled engine by using exhaust gas analysis, single cylinder engine test with gas chromatography was carried out and the experimental results were compared with calculated ones. At the same time universal exhaust gas oxygen sensor which is commonly used for gasoline fuel was also introduced to hydrogen fueled engine. As a consequence, it is evident that unburned hydrogen discharges into exhaust pipe in the vicinity of stoichiometric fuel-air equivalence ratio and discharged hydrogen results in the error of fuel-air equivalence ratio estimation. Also exhaust oxygen sensor is largely affected by hydrogen. Therefore proper correction shall be introduced to calculate the fuel-air equivalence ratio precisely.

To reduce air pollution by the exhaust gases from automotives, it is necessary to control air/fuel ratio appropriate to engine operating condition, which can be achieved by adopting an electronic control system. In this study we designed and fabracated PC-ECU (Personal Computer interfaced - Electronic Control Unit) to develop the automotive engine control system. PC-ECU is made to perform engine control with the application of various control logics instead of the C-ECU. As a first step to develop control logics we applied jump-ramp control to the real engine using a simple on/off O2 sensor and performed engine control by the use of PC-ECU. Also, we introduced a wide band O2 sensor instead of the simple on/off O2 sensor and adopted the PI control. The results show that the control performance in case of using a wide band O2 sensor is much better than in case of using a simple on/off O2 sensor.

An experimental study was carried out to investigate the characteristics of cycle-by-cycle variations of combustion in a spark ignition engine. Cylinder pressure - crank angle histories of the 240 consecutive cycles were measured in the single cylinder by using a personal computer (IBM-PC AT) controlled data acquisition system which is developed for engine tests. From these data, a heat release analysis was performed for cycles and the averaged. It was observed that characteristics of the pressure and combustion rate related parameters varies with operating conditions such as air fuel ratio, ignition timing, and so on. Variation in early flame stage is the major cause for for the cycle-by-cycle variation of combustion. It was also noticed that the variation in early flame stage does not influence the mean effective pressure significantly in case of a rapid burn operation.

The volumetric efficiency for a 4-stroke, single- cylinder, spark- ignition engine is considered. The mathematical model for the gas exchange process was formulated and solved by numerical technique. The mass flow rate, the pressure-time history in cylinder, intake and exhaust pipes, and the volumetric efficiency were calculated. The important parameter affecting volumetric efficiency was the pressure in the pipes. But, the effect of valve timing on volumetric efficiency was small (1, 2)*. The experiments with 3-different cams were performed. The predicted results were compared with experimental data and satisfactory agreement was obtained. As a result, the volumetric efficiency could be predicted with a relatively simple mathematical model.

To improve the cold startability of methanol, methanol-butane mixed fuel was experimented. Engine performance and exhaust emissions are obtained with methanol-butane mixed fuel. These characteristics are compared with those of methanol and gasoline. The mixing ratios of methanol and butane are 50:50 (M50), 80:20 (M80), and 90:10 (M90) based on the calorific value. As a result, M90 produces more power than gasoline and more or less than methanol depending on the engine speed and the excess air ratio. Brake horse power of M90 is higher than that of gasoline by 5 - 10 %, and brake specific fuel consumption is smaller than that of gasoline by 17 % to the maximum based on the calorific value. NOx emission concentrations for M90 are lower than those for gasoline and higher than those for methanol because of the effect of butane, CO emission concentrations are somewhat lower than those for methanol and gasoline.