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In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.

An investigation based on human visual search functions was conducted into the causative factors of traffic accidents at clear intersections in rural areas. The results indicated that it is difficult for drivers to detect a vehicle traveling on a collision course because the vehicle remains in the same position in the driver's visual field. Two systems are introduced to assist drivers' visual searches. One system uses an image processing technique, and the other utilizes DGPS and IVC techniques. This paper presents the development of the assistance system.

Diesel emissions are significant issue worldwide, and emissions requirements have become so tough that. the application of after-treatment systems is now indispensable in many countries To meet even more stringent future emissions requirements, it has become apparent that the improvement of market fuel quality is essential as well as the development in engine and exhaust after-treatment technology. Japan Clean Air Program II (JCAP II) is being conducted to assess the direction of future technologies through the evaluation of current automobile and fuel technologies and consequently to realize near zero emissions and carbon dioxide (CO2) emission reduction. In this program, effects of fuel properties on the performance of diesel engines and a vehicle equipped with two types of diesel NOx emission after-treatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined.

This paper is an attempt to estimate the traffic demand of private vehicles in the Philippines and Thailand toward 2030. Estimation of road traffic volume is one of the most important elements for determining fuel consumption and emission gas levels. The level of passenger car ownership is still low, but there has been a distinct shift toward passenger cars due to the lack of mass transport. In Asian countries, inspection and maintenance and emission standards are the most important policy measures. The projections of car stock are evaluated as the emissions of PM, CO and NOx by applying these policy measures in the case of Thailand.

This work investigated the mechanism of oil dilution by post injection to remove accumulated particulate matter on the diesel particulate filter of diesel engines. We developed a model to simulate post injection spray under low ambient gas pressure conditions. The model can predict the quantity of fuel mass adhered on the cylinder wall. The adhered fuel enters oil sump through the piston ring and cause oil dilution. The fuel in diluted oil evaporates during normal engine operations. We focus on the mechanism of fuel evaporation from diluted oil. The effects of engine speed and oil temperature on the evaporation were investigated. The results showed that the fuel evaporation rate increases with increasing engine speed and oil temperature. Furthermore, we developed an empirical model to predict the fuel evaporation rate of diluted oil through regression analysis with measured data.

For the better understanding of nanoparticles observed on the rode side, adding to the emission test on the chassis dynamometer and engine dynamometer test, possible factors for formation of nanoparticles are investigated. As other possible factors, cold starting of transient test cycle, blow-by gas from heavy duty diesel engine without a positive crankcase ventilation, exhaust braking, and plume mixing of vehicle exhausts were investigated. Nuclei mode particles under the transient test cycles formed during fuel cut period, fuel enrichment period and idling period. Concentration of nuclei mode particles during the idling period are depends on exhaust temperature. The higher exhaust temperature courses the lower number concentration but variation range is within twice. Emission rate of nanoparticles from blow-by gas is one thousandth of tail pipe emissions rate and was found to be negligible.

Newly designed laboratory measurement system, which reproduces particle number size distributions of both nuclei and accumulation mode particles in exhaust emissions, was developed. It enables continuous measurement of nano particle emissions in the size range between 5 and 1000 nm. Evaluations of particle number size distributions were conducted for diesel vehicles with a variety of emission aftertreatment devices and for gasoline vehicles with different combustion systems. For diesel vehicles, Diesel Oxidation Catalyst (DOC), urea-Selective Catalytic Reduction (urea-SCR) system and catalyzed Diesel Particulate Filter (DPF) were evaluated. For gasoline vehicles, Lean-burn Direct Injection Spark Ignition (DISI), Stoichiometric DISI and Multi Point Injection (MPI) were evaluated. Japanese latest transient test cycles were used for the evaluation: JE05 mode driving cycle for heavy duty vehicles and JC08 mode driving cycle for light duty vehicles.

This paper proposes a new mixing-controlled, low temperature combustion (LTC) approach for high-speed direct injection (HSDI) diesel engines. The purpose of this approach is to avoid the excessively high pressure-rise rate (PRR) of premixed, kinetics-controlled LTC and to enable the low nitrogen oxides (NOx) combustion to operate over the wide speed and load range of the engine. To address the soot/noise trade-off at high load LTC operating conditions, the pressure modulated multiple-injection coupled with swirl control was applied. This injection strategy enables the injection of high pressure (HP) main spray into the local high temperature region of the already burning low pressure (LP) pilot spray injected from the neighboring injection hole. By employing this injection strategy, the equivalence ratio (φ) distribution of mixture is drastically varied during main combustion processes.

A new combustion system targeting a drastic decrease in NOx emission and a brake specific energy consumption equivalent to that of a DI diesel engine has been developed. In this new combustion system, a lean burn system using early injection was employed to reduce NOx emission and an auto-ignition DI engine system was employed to achieve the low energy consumption. Methanol was used as the fuel for reducing NOx emission. The objective of this study is to clarify the possibility of the system for the auto-ignition of a premixed lean mixture of methanol fuel. This study shows that the gas temperature at ignition, Tig, is the predominant factor affecting auto-ignition. Auto-ignition occurs when Tig exceeds approximately 1000K. The methanol lean burn system in an auto-ignition DI engine drastically decreased NOx emission with almost the same brake specific energy consumption as a diesel engine in the middle load region.

In this study, a MPT-HFRR (Multi-Pressure/Temperature High-Frequency Reciprocating Rig) was manufactured based on a diesel fuel lubricity test apparatus. The MPT-HFRR was designed to be used for conventional test methods as well as for liquefied gas fuel tests. Lubricity tests performed on a calibration standard sample under both atmospheric pressure and high pressure produced essentially constant values, so it was determined that this apparatus could be used for assessing the lubricity of fuel. Using this apparatus, the improvement of lubricity due to the addition of a DME (Dimethyl Ether) fuel additive was investigated. It was found that when 50ppm or more of a fatty acid lubricity improver was added, the wear scar diameter converged to 400μm or less, and a value close to the measured result for Diesel fuel was obtained. The lubricity obtained was considered to be generally satisfactory.

In this research, a test apparatus (VPT-HFRR) for evaluating lubricity was manufactured at an arbitrary pressure according to the lubricity test method (HFRR) for diesel fuel. The lubricity of LPG blended fuel (LBF) for diesel engines was examined using VPT-HFRR., This was a value close to that of diesel fuel, and when a suitable lubricity had been maintained, it was checked. Prototype trucks were manufactured and their durability was examined. After a run of 70,000km or more, no serious trouble had occurred, and when LBF was maintained at a suitable lubricity, it was checked.

Fuels of wide range of density and viscosity were tested by using a DI diesel engine that conforms to present Japanese regulations. A total of 9 fuels was tested. Six test fuels were commercial automotive diesel fuel available in Japan. In order to expand the density range, test fuels of kerosene, high-density diesel fuel and automotive diesel fuel in Singapore were also included. The density range was 0.796 to 0.856 (g/cm3), and the viscosity range was 1.52 to 5.44 (mm2/s). The test mode was Japanese D13. Also, some fuels were tested by the Japanese transient test mode. Moreover, fuel spray was observed by an optical method to clarify the relationship between viscosity and Sauter mean diameter.

The objective of this study is to improve tire hydroplaning performance by examining the arrangement of the tread grooves, based on water flow. It is important to smoothly channel the water through the tread grooves to improve performance. For this purpose, flow around the tire contact area was visualized by particle tracing. The velocity and the direction of flow in front of the contact area became clear as a vector map. This vector map indicated that the direction of the flow depends primarily on the lateral position, i.e., the distance from the tread center. Tread grooves parallel to the flow vector were designed based on this result. The visualization of the improved tire demonstrated that water flowed smoothly along the grooves. In addition, a drum test indicated increased cornering force at high speed.

Emission regulations for diesel-powered vehicles have been gradually tightening. Installation of after-treatment devices such as diesel particulate filters (DPF), NOx storage reduction (NSR) catalysts, and so on is indispensable to satisfy rigorous limits of particulate matter (PM) and nitrogen oxides (NOx). Japan Clean Air Program II Oil Working Group (JCAPII Oil WG) has been investigating the effect of engine oil on advanced diesel after-treatment devices. First of all, we researched the impact of oil-derived ash on continuous regeneration-type diesel particulate filter (CR-DPF), and already reported that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF [1]. In this paper, impact of oil-derived sulfur and phosphorus on NSR catalyst was investigated using a 4L direct injection common-rail diesel engine with turbo-intercooler. This engine equipped with NSR catalyst meets the Japanese new short-term emission regulations.

Impact of oil-derived ash on the pressure drop of continuous regeneration-type diesel particulate filter (CR-DPF) was investigated through 600hrs running test at maximum power point on a 6.9L diesel engine, which meets the Japanese long-term emission regulations enacted in 1998, using approximately 50ppm sulfur content fuel. Sulfated ash content of test oils were varied as 0.96, 1.31, and 1.70 mass%, respectively. During the running test, the exhaust pressure drop through CR-DPF was measured. And after the test, the ventilation resistance through CR-DPF was also evaluated before and after the baking process, which was applied to eliminate the effect of soot accumulated in CR-DPF. The results revealed that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF. According to microscope examination of the baked DPF, ash was mainly accumulated on the wall surface of CR-DPF, and that seemed to be related to the magnitude of pressure drop caused by ash.

Biodiesel Fuel (BDF) Research Work Group works on identifying technological issues on the use of high biodiesel blends (over 5 mass%) in conventional diesel vehicles under the Japan Auto-Oil Program started in 2007. The Work Group conducts an analytical study on the issues to develop measures to be taken by fuel products and vehicle manufacturers, and to produce new technological findings that could contribute to the study of its introduction in Japan, including establishment of a national fuel quality standard covering high biodiesel blends. For evaluation of the impacts of high biodiesel blends on performance of diesel particulate filter system, a wide variety of biodiesel blendstocks were prepared, ranging from some kinds of fatty acid methyl esters (FAME) to another type of BDF such as hydrotreated biodiesel (HBD). Evaluation was mainly conducted on blend levels of 20% and 50%, but also conducted on 10% blends and neat FAME in some tests.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. In the impact on exhaust emissions, the impact of high biodiesel blends into diesel fuel on diesel emissions was evaluated. The wide variety of biodiesel blendstock, which included not only some kinds of fatty acid methyl esters(FAME) but also hydrofined biodiesel(HBD) and Fischer-Tropsch diesel fuel(FTD), were selected to evaluate. The main blend level evaluated was 5, 10 and 20% and the higher blend level over 20% was also evaluated in some tests. The main advanced technologies for exhaust aftertreatment systems were diesel particulate filter(DPF), Urea selective catalytic reduction (Urea-SCR) and the combination of DPF and NOx storage reduction catalyst(NSR).

Four urea SCR systems were developed and evaluated on a C/D and on the road to investigate their potential for Japanese emission regulations in 2005 and beyond. Test results showed that NOx conversion ratios were 50 to 70% during the Japanese D13 mode cycle, and the ratios under the transient driving cycle were lower than those tested during a steady state. Unregulated emissions, such as benzene, aldehyde and benzo[a]pyrene, existed either at a trace level using the oxidation catalyst, or lower than a base diesel engine, when no oxidation catalyst was used. The health effects of particulate matter emitted from the SCR system were almost the same as those from conventional diesel engines, as evaluated by the Ames test and in vitro micronucleus test. Thermal degradation products, such as cyanuric acid and melamine, were two to four figures lower compared with the toxicological information of Safety Information Resources Inc. (SIRI).

A prototype CNG engine for heavy-duty trucks has been developed. The engine had sufficient output in practical use, and the green-house gas emission rate was below that of the base diesel engine. Furthermore, the NOx emission rate was reduced to 0.16 g/kWh in the JE05 mode as results of having fully adjusted air fuel ratio control. The measured emission characteristics of particles from the prototype CNG engine demonstrated that oil consumption was related to the number of particles. Moreover, when oil consumption is at an appropriate level, the accumulation mode particles are significantly reduced, and the nuclei mode particles are fewer than those of diesel-fueled engines.

This study employed a diesel particulate generator (DPG), with an installed engine oil injector for soot and ash accumulation in a diesel particulate filter (DPF). Ash was generated by engine oil injection into the diesel burner flame. The amount of soot accumulation per loading varied from 0.5 g/L to 8 g/L while ash accumulation amount per loading was maintained at 0.5 g/L. Initially, ash accumulation distribution in the DPF was visualized using X-ray computed tomography (CT). It was revealed that the form of ash accumulation changed depending on the amount of soot accumulation before active regeneration, i.e., a large amount of soot accumulation resulted in plug ash, whereas a small amount of soot accumulation resulted in wall ash. To clarify ash accumulation mechanisms, soot and ash transport behavior in DPF during active regeneration process was directly observed using a high-speed camera through an optically accessible D-shaped cut DPF covered with a quartz glass plate.