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Trivalent chromate coating is replacing the conventional hexavalent chromate coating applied on zinc plating. Zinc plating uses one of three types of plating baths (zincate, cyanide and chloride) according to the characteristics required of subject parts. It has been recognized that trivalent chromate coating provides different corrosion resistance depending on the type of zinc plating bath used. Zinc plating with chromate coating were analyzed to clarify the cause of the corrosion resistance variation with the type of zinc plating bath. It has been revealed that the chromate coating thickness and the condition of top SiO2 layer vary with the type of zinc plating bath, resulting in corrosion resistance variation.

A series calculation methodology from the injector nozzle internal flow to the in-cylinder fuel spray and mixture formation in a diesel engine was developed. The present method was applied to a valve covered orifice (VCO) nozzle with the recent common rail injector system. The nozzle internal flow calculation using an Eulerian three-fluid model and a cavitation model was performed. The needle valve movement during the injection period was taken into account in this calculation. Inside the nozzle hole, cavitation appears at the nozzle hole inlet edge, and the cavitation region separates into two regions due to a secondary flow in the cross section, and it is distributed to the nozzle exit. Unsteady change of the secondary flow caused by needle movement affects the cavitation distribution in the nozzle hole, and the spread angle of the velocity vector at the nozzle exit.

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.

We have developed a novel engine cycle simulation program (UniDES: universal diesel engine simulator) to reproduce the diesel combustion process over a wide range of engine operating parameters, such as the amount of injected fuel, the injection timing, and the EGR ratio. The approach described in this paper employs a zoning model, where the in-cylinder region is divided into up to five zones. We also applied a probability density function (PDF) concept to each zone to consider the effect of spatial non-homogeneities, such as local equivalence ratios and temperature, on the combustion characteristics. We linked this program to the commonly used commercial GT-Power® software (UniDES+GT). As a result, we were able to reproduce transient engine behavior very accurately.

The aim of this research is to develop the diesel combustion simulation (UniDES: Universal Diesel Engine Simulator) that incorporates multiple-injection strategies and in-cylinder composition changes due to exhaust gas recirculation (EGR), and that is capable of high speed calculation. The model is based on a zero-dimensional (0D) cycle simulation, and represents a multiple-injection strategy using a multi-zone model and inhomogeneity using a probability density function (PDF) model. Therefore, the 0D cycle simulation also enables both high accuracy and high speed. This research considers application to actual development. To expand the applicability of the simulation, a model that accurately estimates nozzle sac pressure with various injection quantities and common rail pressures, a model that accounts for the effects of adjacent spray interaction, and a model that considers the NOx reduction phenomenon under high load conditions were added.

High fuel efficiency and low emission technologies, such as Direct Injection (DI) gasoline and diesel engines and hybrid powertrains, have been developed to resolve environmental and energy resource issues. The hybrid powertrain system has achieved superior power performance as well as higher system efficiency and is expected to be a core powertrain technology because it is compatible with various power sources including fuel cells. It becomes important to control complicated hybrid systems that consist of not only a powertrain but also vehicle systems such as regenerative braking. Model-based control and calibration enables both control strategy optimization and control system development efficiency improvement.

Exhaust emissions are well known to have adverse impacts on human health. Studies have demonstrated that there is an association between ambient particulate matter (PM) levels and various harmful cardiopulmonary conditions. Soot exhaust from diesel engines can be a significant contributor to airborne pollutants. A key component in PM level control for a diesel engine is a diesel particulate filter (DPF). This device traps soot while allowing other exhaust gases to pass unhindered. However, the performance of diesel particulate filters can change with increasing soot loadings and thus may require regeneration or replacement. Improved understanding of diesel particulate filters is dependent upon the knowledge of the actual soot loading and the soot distribution within the DPF. Neutron radiography (NR) has been identified as an effective means of non-destructively identifying hydrogen or carbon adsorbed in PM.

Generally, soot emissions increase in diesel engines with smaller bore sizes due to larger spray impingement on the cavity wall at a constant specific output power. The objective of this study is to clarify the constraints for engine/nozzle specifications and injection conditions to achieve the same combustion characteristics (such as heat release rate and emissions) in diesel engines with different bore sizes. The first report applied the geometrical similarity concept to two engines with different bore sizes and similar piston cavity shapes. The smaller engine emitted more smoke because air entrainment decreases due to the narrower spray angle. A new spray design method called spray characteristics similarity was proposed to suppress soot emissions. However, a smaller nozzle diameter and a larger number of nozzle holes are required to maintain the same spray characteristics (such as specific air-entrainment and penetration) when the bore size decreases.

1 Recently, demand for small-bore compact vehicle engines has been increasing from the standpoint of further reducing CO2 emissions. The generalization and formulation of combustion processes, including those related to emissions formation, based on a certain similarity of physical phenomena regardless of engine size, would be extremely beneficial for the unification of development processes for various sizes of engines. The objective of this study is to clarify what constraints are necessary for engine/nozzle specifications and injection conditions to achieve the same combustion characteristics (such as heat release rate and emissions) in diesel engines with different bore sizes.

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.

In recent years, problems such as global warming, the depletion of natural resources, and air pollution caused by emissions are emerging on a global scale. These problems call for efforts directed toward the development of fuel-efficient engines and exhaust gas reduction measures. As a solution to these issues, performance improvements should be achieved on the oil that lubricates the sliding sections of engines. This report points to features required of future engine oil-such as contribution to fuel consumption, minimized adverse effects on the exhaust gas aftertreatment system, and improved reliability achieved by sludge reduction-and discusses the significance of these features. For engine oil to contribution of engine oil to lower fuel consumption, we examined the effects of reduced oil viscosity on friction using gasoline and diesel engines.

Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. This paper describes the improvement of piston bowl geometry to achieve a more homogeneous gas flow and fuel-air mixture. This concept reduced fuel consumption by 2.5% compared to the original piston bowl geometry, while also reducing NOx emissions by 10%.

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 reduction of the heat loss from the in-cylinder gas to the combustion chamber wall is one of the key technologies for improving the thermal efficiency of internal combustion engines. This paper describes an experimental verification of the “temperature swing” insulation concept, whereby the surface temperature of the combustion chamber wall follows that of the transient gas. First, we focus on the development of “temperature swing” insulation materials and structures with the thermo-physical properties of low thermal conductivity and low volumetric heat capacity. Heat flux measurements for the developed insulation coating show that a new insulation material formed from silica-reinforced porous anodized aluminum (SiRPA) offers both heat-rejecting properties and reliability in an internal combustion engine. Furthermore, a laser-induced phosphorescence technique was used to verify the temporal changes in the surface temperature of the developed insulation coating.

A study was conducted to reduce unburned oil fractions in diesel particulate matter (PM) by improving oil consumption. A method utilizing radioisotope 14C was developed to measure the unburned oil fractions separately for the four paths by which oil is consumed: valve stem seals, piston rings, PCV system, turbocharger. The conversion ratio of oil consumption to PM was calculated by comparing the unburned oil emission rates with oil consumption rates, which were obtained by the use of the 35S tracer method. The result in an experimental diesel engine shows the highest conversion ratio for the oil leaking through the valve stem seals. The modifications to the engine were thereby focused on reducing the leakage of the stem seals. This stem seal modification, along with piston ring improvements, reduced oil consumption, resulting in the unburned oil fractions in PM being effectively reduced.

The details of Di-Air, a new NOx reduction system using continuous short pulse injections of hydrocarbons (HC) in front of a NOx storage and reduction (NSR) catalyst, have already been reported. This paper describes further studies into the deNOx mechanism, mainly from the standpoint of the contribution of HC and intermediates. In the process of a preliminary survey regarding HC oxidation behavior at the moment of injection, it was found that HC have unique advantages as a reductant. The addition of HC lead to the reduction or metallization of platinum group metals (PGM) while keeping the overall gas atmosphere in a lean state due to adsorbed HC. This causes local O₂ inhibition and generates reductive intermediate species such as R-NCO. Therefore, the specific benefits of HC were analyzed from the viewpoints of 1) the impact on the PGM state, 2) the characterization of intermediate species, and 3) Di-Air performance compared to other reductants.

In recent years, engine control systems have become more and more complex because of the growing pressure to develop technical innovations due to social pressures such as global warming and the depletion of fossil fuels. On the other hand, products must be launched on the market in a timely manner and at low cost. For these reasons, calibration processes have become more sophisticated. It is possible to improve the efficiency of calibration by making good use of models, and a calibration process that incorporates models is called model based calibration (MBC). MBC is a valid means of reducing the number of measurement points to some extent by statistical engine modeling and design of experiment (DoE) methodology which places measurement points in order to maximize modeling accuracy. However, it is still necessary to spend much time carrying out boundary detection testing before DoE.

Current and future engine technologies and fuels are mutually dependent. The increased use of alternative fuels has been linked to deterioration in performance of injectors, fuel filters and engines as a result of insoluble deposit formation. The present work aimed to study the impact of Diesel/biodiesel blends formulation (biodiesel feedstock and content) and temperature on the oxidation stability based on total acid number (TAN). The biofuels used in the fuel matrix were: rapeseed, soy and palm methyl esters (RME, SME and PME respectively). The Diesel/biodiesel blends were made with 0%v/v, 5%v/v, 10% v/v and 20%v/v of biodiesel blended with additive-free new Diesel. The oxidation stability of Diesel/biodiesel blends was to evaluate during 6 months fuels storage, under 20°C and 40°C, and fuels severe oxidation into a reactor vessel to better understand the parameters leading to fuel oxidation on-board.

The International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.

The regulation of emissions discharged from diesel engines has become stricter worldwide. The regulatory values allowed for particulate matter (PM) as well as NOx will be lowered, especially in the Europe Euro 5, the U.S. EP 07, and the new Japanese long-term regulations. Since there is a tradeoff between the PM and NOx that are discharged from diesel engines, new emission reduction measures will be needed in order to greatly reduce both at the same time. By coating DPFs (Diesel Particulate Filters), which have been studied before, with NOx storage reduction catalysts, it has been found that simultaneous reduction of PM and NOx is possible, and so research was carried out in order to optimize a DPF for this type of system use. The DPF developed was used in the European DPNR (Diesel Particulate-NOx Reduction System) subject vehicles by Toyota Motor Corporation, and actual trial runs in Europe were performed.