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Fischer-Tropsch Diesel (FTD) fuel is expected to be a promising clean diesel fuel in the future because of its characteristics of zero sulfur, zero aromatics and a high cetane number. However, the optimum fuel properties for diesel engines have not been realized. In this study, the effects of cetane number and distillation characteristics on engine-out PM emissions from a conventional direct injection diesel engine were investigated by using paraffinic fuels which were made to simulate FTD fuel. From the results of the vehicle exhaust emissions test and engine dynamometer test, it was found that the narrow distillation characteristics (which eliminates heavy hydrocarbon fraction) could reduce the soluble organic fraction (SOF) in PM emissions, and the excess high cetane number characteristic promoted the formation of insoluble organic fraction (ISOF).

We have realized ultra low exhaust emission that meets U-LEV standards in Japan by applying a simultaneous reduction system of NOx and particulate matter (hereinafter referred to as PM) to the diesel engine for light-duty trucks. This system has been introduced to the Japanese market since September 2003. The basic technologies comprise Diesel Particulate-NOx Reduction system (DPNR), common rail injection system necessary for accurately controlling the catalyst bed temperature and the air to fuel ratio, electrically controlled EGR system, high-efficiency EGR cooler, and the fuel injector installed on the upper stream of catalyst that feeds over-rich fuel-air mixture for NOx reduction with DPNR catalyst and SOx discharging. To realize simultaneous reduction of NOx and PM with DPNR, the important issues include the clogging of PM to the filters after continuous driving at low vehicle speed and the sulfur poisoning of the catalyst.

Effects of fuel distillation characteristics and cetane number on premixed charge compression ignition (PCCI) combustion were investigated for the purpose of reducing NOx and PM emissions from a direct injection diesel engine. The test engine had a hole type injection nozzle for conventional diesel combustion at high load operation. A low compression ratio and cooled EGR were applied to the test engine in order to reduce the compression temperature for avoiding pre-ignition. The investigation results show that, in the case of ignition control by EGR, a light fuel with lower distillation characteristics had an advantage of reducing smoke at higher loads. This means that high volatility fuel is effective in promoting lean mixture formation of fuel and air during the ignition delay. Moreover, lowering the cetane number was effective in reducing NOx emissions by suppression of combustion temperature.

A new diesel after-treatment system, Diesel Particulate and NOx Reduction System (DPNR), is being developed for reducing PM and NOx emissions. We examined the effects of sulfur content in lubricants on exhaust NOx emission from DPNR catalyst, and examined the PM reduction ability using sulfur-free and aromatics-free fuel. After vehicle durability testing of 40,000 km without forced regeneration of PM and sulfur poisoning on DPNR catalyst, deterioration of DPNR was lower than using higher sulfur contents in fuel and oil. In addition to decreasing fuel sulfur, decreasing oil sulfur was also effective to maintain high NOx conversion efficiency. Although the catalyst was poisoned by sulfur in the lubricants, the influence of oil sulfur poisoning on the catalyst was lower than fuel sulfur poisoning. On the other hand, engine out PM emissions decreased by 70 % because of aromatics-free fuel. The pressure drop of DPNR did not increase during the 40,000 km vehicle durability test.

A new after-treatment system called DPNR (Diesel Particulate-NOx Reduction System) has been developed for simultaneous and continuous reduction of particulate matter (PM) and nitrogen oxides (NOx) in diesel exhaust gas. This system consists of both a new catalytic technology and a new diesel combustion technology which enables rich operating conditions in diesel engines. The catalytic converter for the DPNR has a newly developed porous ceramic structure coated with a NOx storage reduction catalyst. A fresh DPNR catalyst reduced more than 80 % of both PM and NOx. This paper describes the concept and performance of the system in detail. Especially, the details of the PM oxidation mechanism in DPNR are described.

The effects of gasoline fuel properties on exhaust emissions were investigated. Port injection LEVs, a ULEV, a prototype SULEV which were equipped with three–way (3–way) catalysts and also two vehicles with direct injection spark ignition (DISI) engines equipped with NOx storage reduction (NSR) catalysts were tested. Fuel sulfur showed a large effect on exhaust emissions in all the systems. In the case of the DISI engine with the NSR catalyst, NOx conversion efficiency and also regeneration from sulfur poisoning were dramatically improved by reducing sulfur from 30ppm to 8ppm. Distillation properties also affected the HC emissions significantly. The HC emissions increased in both the LEV and the ULEV with a driveability index (DI) higher than about 1150 (deg.F). The ULEV was more sensitive than the LEV. These results show that fuel properties will be important for future technologies required to meet stringent emission regulations.

Influence of sulfur poisoning on NOx storage - reduction catalysts (NSR catalysts) was examined using both model gas and an actual vehicle. Deterioration of NSR catalysts is explained as the balance of sulfate formation in lean operating conditions and the amount of sulfate decomposed under rich operating conditions. This study focused on sulfate decomposition characteristics of NSR catalysts. First, sulfate decomposition characteristics of an NSR catalyst were examined in a model gas test. It was found that the initial temperature of SOx release was higher than the sulfur poisoning temperature. Crystal growth of sulfate by increasing temperature was assumed, and hence suppressed SOx release. Second, various sulfur concentrations (8 - 500 ppm) in gasoline were used for vehicle durability. The duration of one durability cycle was 1,260 seconds, including a 60 second regeneration of sulfur poisoning (AFR 14.2, 700 °C).

This paper presents wireless multimedia communications with the intelligent transport system (ITS). First, the new concept of "environment communication" is introduced which combines one's environmental data and information with personal communication technology; the understanding is one's environment continually changing. This concept can secure his safe movement and/or control his level of comfort. The wireless agent is also proposed as one element of environment communication. This technology combines the conventional mobile agent function with information specific to the mobile terminal environment. Also, the combination of the wireless agent and ITS is discussed from the viewpoints of effective data communication. Furthermore, the concept of personal navigation based on personal handy-phone system (PHS) technology is introduced. Last, a couple of technologies to improve wireless transmission performance are discussed.

New ductile cast iron flywheel integrated with gear and its manufacturing process were developed to reduce the manufacturing steps and cost compared with conventional flywheel around which a steel ring gear is fit. In this process, the ring gear teeth around a cast iron flywheel are formed directly in net shape and free from any defect by the hot form-rolling method, followed by the thermomechanical treatment in a short time. The gear is superior to that made by the conventional hobbing and heat treatment in accuracy, strength and anti-wear property.

A new 3-way catalyst with NOx conversion performance for lean-burn engines has been developed. The catalyst oxidizes NOx and stores the resulting nitrate, which is then reduced by HC and CO during engine operation around the stoichiometric air/fuel ratio. Both the composition of the storage component and the particle sizes of the noble metal were optimized. In addition, a special air fuel mixture control has been developed to make the best of the NOx storage-reduction function. The present catalyst showed 90% conversion efficiency and improved fuel economy by 4% in the Japanese 10-15 mode test cycle. The efficiency remained at 60% or more after durability test.

The emission characteristics of hydrocarbons during the cold start and the warm-up have been investigated. Timed sampling of hydrocarbon emissions upstream and downstream of a close-coupled catalytic converter have been carried out. The experimental results show that the emission characteristics of hydrocarbons are influenced by both the engine operating conditions and the heating characteristics of the catalytic converter. In the case of engine-out hydrocarbons, the total amount of hydrocarbons drastically decreases but the percentage contribution of the C2-C4 olefins to the engine-out hydrocarbons increases as the warm-up proceeds. Since these olefins have relatively high maximum incremental reactivity (MIR) factors, the specific reactivity (SR) of the engine-out hydrocarbons gradually increases during the warm-up. The adsorption and desorption processes of the engine-out hydrocarbons on the catalyst occur before the catalyst light-off.

The effects of fuel properties and emission control systems on exhaust hydrocarbon emissions have been studied. Using fourteen fuels with different properties, exhaust hydrocarbon emissions were measured for the two vehicle types with different emission control systems, under body catalyst and closed coupled catalyst, under the Federal Test Procedure. The fuel properties included high and low concentrations of olefins and aromatics as well as high and low T90. In addition, two fuels contained MTBE. The hydrocarbon emissions were discussed from the view point of the ozone reactivity and ozone formation potential. The results show that the high ozone reactivity of exhaust emissions are mainly caused by the olefins and aromatics in fuels. And also, the effects of fuel property change on exhaust emissions for the vehicle with an under body catalyst are more sensitive than the case of the vehicle with a closed coupled catalyst.

To reduce diesel odor its first essential that a simple but accurate method of measuring odor level be available. Various approaches were considered but found to give poor correlation to the odor intensity as assessed by professional perfumers. However a method utilizing a cold trap and measurement of the odor components' pH correlated very closely to the human olfactory sense. This method proved capable of accurately measuring even small changes in odor level and was applied to a study of the effects on odor Levels of changes in engine specifications and operating conditions. The results indicated that squish area geometry greatly affects diesel odor.

The white smoke generated by a diesel engine was analyzed and found to consist mainly of hydrocarbons. Test results indicated that the emission level depends on ambient temperature. A compact white smoke meter was developed to enable emission levels to be accurately measured. The internal temperature of this meter is controlled so that white smoke is generated within the measuring device. The meter was used to evaluate the effectiveness of various white smoke emission control devices for the DI diesel engine. The results indicated that an intake air heater offers the greatest potential. Accordingly, a new intake air heater with ceramic PTC thermistor having a very high heating efficiency was developed to reduce white smoke emission.

An analytical study has been carried out to investigate how the factors affecting ignition and formation of NOx and smoke can be influenced in indirect injection (IDI) diesel engines in order to increase engine output and reduce idling noise. It was found that controlling the heat release ratio between the swirl and main chambers was effective in reducing smoke and NOx emissions and in improving engine output. It vas also found that making the air jet flow counter to the fuel spray injected into the swirl chamber was effective in dispersing and atomizing fuel. This shortened the ignition delay period and reduced idling noise as a result. These factors have been incorporated into a newly developed dual-throat jet combustion system in which a sub-throat is provided in the swirl chamber, in line with the center axis of the fuel injection nozzle, in addition to the ordinary main throat.