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Merging a CAE shape optimization system and a concept Taguchi method SN-ratio index, a robustness-focused automated shape optimization method has been developed. Applying this method to diesel intake ports, with mold position tolerance set as the error factor, SN-ratio was defined for swirl stability. As a result of the optimization provided by a multi-objective genetic algorithm, simultaneous improvement of flux, swirl rotation and SN ratio was achieved.

Previous studies have investigated the impacts of biofuel usage on the performance, drivability and durability of modern diesel engines and exhaust after-treatment systems including test work with different types, concentrations and mixtures of bio fuel components. During this earlier work vehicle fuel filter blocking issues were encountered during a field trial using various types of EN 14214 compliant Fatty Acid Methyl Ester (FAME) blended into EN 590 diesel. This paper summarises a subsequent literature review that was carried out looking into potential causes of this filter blocking and further work that was then carried out to expand on the findings. From this, a laboratory study was carried out to assess the increase in fuel filter blocking tendency (FBT) when various FAMEs from mixed sources were blended into EN 590 diesel at different concentrations, including levels above those currently allowed in the European market.

Knock in spark-ignition (SI) engines has been a subject of many research efforts and its relationship with high efficiency operating conditions keeps it a contemporary issue as engine technologies push classical limits. Despite this long history of research, literature is lacking coherent and generalized descriptions of how knock is affected by changes in the full cylinder temperature field, residence time (engine speed), and air/fuel ratio. In this work, two dimensionless numbers are applied to fully 3D SI conditions. First, the characteristic time of autoignition (ignition delay) is compared against the characteristic time of end-gas deflagration, which was used to predict knocking propensity. Second, the temperature gradient of the end-gas is compared against a critical detonation-based temperature gradient, which predicts the knock intensity.

From the viewpoint of the global warming restraint, reduction of exhaust emissions from diesel engine is urgent demand. However, it needs further development in combustion control besides after treatment system. Larger amount of EGR (Exhaust Gas Recirculation) is effective to reduce NOx emission. On the other hand, in-cylinder physical conditions greatly influence on self-ignition and combustion process, especially low O2 fraction charged gas owing to excessive EGR causes misfire. A drastic solution for this problem, fuel injection timing should be optimally manipulated based on predicted ignition delay period before actual injection. For this purpose, Toyota has developed a model based diesel combustion control concept to avoid the misfire and to keep low emission combustion includes in transient condition.

Our two types of NOx storage-reduction (NSR) catalyst have been tested under various conditions of thermal endurance; the performance of these catalysts have been regressed to give the formulas that enable to estimate the performance after thermal endurance; and we have found the method to simplify (shorten the duration of) the thermal endurance tests and that the thermal deterioration of NSR catalysts is controlled by the worst condition of endurance (at least approximately). The regression formula for the amount of potassium that contributes to the catalyst performance (active K) after the endurance has also been obtained. These formulas predict that the amount of active K is the least for the worst condition of endurance and suggest a difference in deterioration mechanism that reflects the performance between low and high temperatures and the portion of worse deterioration (front or rear).

NO2 sources of roadside atmosphere at Matsubarabashi monitoring station in Tokyo were investigated analytically. The result showed that contribution of urban background is dominant from November to February and NO oxidation with O3 has large contribution from April to September. NO2 air quality standard will be achieved by reducing vehicle NOx emission to post-new long-term regulation level. The analytical method was verified by using our developed simulation system, which consists of micro traffic flow analyzer and CFD-based, unsteady-state diffusion with chemical reaction solver.

The use of lead-free (Pb-free) solder and plating in onboard electronic components has accelerated rapidly in recent years, but solutions have yet to be found for the issues of whisker generation in tin (Sn) plating and crack initiation in Pb-free solder, despite widespread research efforts. Analysis of the whisker generation mechanism has focused on internal energy levels and crystal orientation, and analysis of the crack initiation mechanism in Pb-free solder has examined changes in the grain boundaries of Sn crystals.

The dissolution and exfoliation of chromium plating specific to Russia was studied. Investigation and analysis of organic compounds in Russian soil revealed contents of highly concentrated fulvic acid. Additionally, it was found that fulvic acid, together with CaCl2 (a deicing agent), causes chromium plating corrosion. The fulvic acid generates a compound that prevents reformation of a passivation film and deteriorates the sacrificial corrosion effectiveness of nickel.

The purpose of this study is to analyze the piston skirt friction reduction effect of a diamond-like carbon (DLC)-coated wrist pin. The floating liner method and elasto-hydrodynamic lubrication (EHL) simulation were used to analyze piston skirt friction. The experimental results showed that a DLC-coated wrist pin reduced cylinder liner friction, and that this reduction was particularly large at low engine speeds and large pin offset conditions. Friction was particularly reduced at around the top and bottom dead center positions (TDC and BDC). EHL simulation confirmed that a DLC-coated wrist pin affects the piston motion and reduces the contact pressure between the piston skirt and cylinder liner.

By using analytical techniques (FT-IR, TG-MS, ICP) and DFT calculations, the potassium (K) used as a storage component in NOx Catalysts can be analyzed. The results from this study show that the, K exists as K2CO3, and that the amount, molecular structure, and thermal stability of K2CO3 are different, depending on the support material (ZrO2, Al2O3, or TiO2). If the amount of K that interacts with the support to form an inactive complex oxide is decreased, the amount of K2CO3 and NOx storage is increased. The amount of the inactive K varies with the basicity of the supports. K2CO3 that exists in unstable structures on the supports can be easy to react with NOx to form the nitrate. So, the higher the quantity of unstable K2CO3, the higher the NOx storage capacity. Based on these results, a development guideline was proposed to improve the NOx storage performance.

Diesel particulate and NOx reduction system (DPNR) is an effective technology for the diesel after-treatment system, which can reduce particulate matter (PM) and nitrogen oxides (NOx) simultaneously. Further improvement of the DPNR is expected for cleaner air in the future. The catalyst for the DPNR (called DPNR catalyst) consists of a NOx Storage Reduction (NSR) catalyst coated onto a Diesel Particulate Filter (DPF). The development of the DPNR catalyst for the decrease of exhaust weight has been considered before now with respect to the PM combustion. But it will be necessary to focus on PM particle number emissions in the future. In this study, the relationship between the pore structure of the DPNR catalyst and the trapping of PM to lower particle number was clarified by evaluating a high-porosity, large-pore cordierite DPF with an average pore size of 20 μm or greater. Furthermore, the optimal pore structure to trap PM particles in a highly effective manner was discussed.

Behavior of sprays formed by slit nozzle as well as swirl nozzles with the spray cone angle in the range of 40° ∼110 ° were studied in a constant volume N2 gas chamber. The fuels used are iso-pentane, n-heptane, benzene and gasoline. The ambient pressure and temperature were raised up to 1.0 MPa and 465 K, respectively. The injection pressure was mainly set at 8 MPa. Spray penetrates at an almost constant speed for a while after injection start and begins to decelerate at a certain point. This point was judged as breakup point, based on a momentum theory on spray motion, the observation of spray inside and the analysis of the spray front reacceleration which occurs under highly volatile condition.

Since the regulations of CO2 emissions have been tightened in each country recently, each automotive manufacturer has responded by bringing competitive technologies that maximize efficiency while promoting vehicle electrification such as xEV. Not only the efficiency, we need to meet or exceed occupant performance and comfort expectations. The climate control system expends a large amount of energy to keep a comfortable environment, having a significant impact on fuel consumption and EV driving range. Therefore, many manufacturers try to save energy and improve occupant comfort quickly by using not only the conventional convective heating by HVAC but also the conductive heating to heat the human body directly such as seat and steering wheel heater. In this study, a radiative heater, which is more efficient than a convective heating to warm anterior thigh and shin where a conductive heating cannot warm, was applied to vehicle.

To meet future stringent emission regulations such as Euro6, the design and control of diesel exhaust after-treatment systems will become more complex in order to ensure their optimum operation over time. Moreover, because of the strong pressure for CO₂ emissions reduction, the average exhaust temperature is expected to decrease, posing significant challenges on exhaust after-treatment. Diesel Oxidation Catalysts (DOCs) are already widely used to reduce CO and hydrocarbons (HC) from diesel engine emissions. In addition, DOC is also used to control the NO₂/NOx ratio and to generate the exothermic reactions necessary for the thermal regeneration of Diesel Particulate Filter (DPF) and NOx Storage and Reduction catalysts (NSR). The expected temperature decrease of diesel exhaust will adversely affect the CO and unburned hydrocarbons (UHC) conversion efficiency of the catalysts. Therefore, the development cost for the design and control of new DOCs is increasing.

The effects of intake dilution with various dilution gases including nitrogen, argon, and carbon dioxide on low temperature diesel combustion were investigated in a naturally aspirated DI diesel engine to understand the mechanism of the simultaneous reductions in smoke and NOx with ultra-high EGR. NOx almost completely disappears with the intake oxygen concentration diluted below 16% regardless of the kind of dilution gas. Smoke emissions decrease with increased heat capacity of the charged gas due to promotion of mixture homogeneity with longer ignition delays. Intake dilution with the 36% CO2 + 64% Ar mixture which has a similar specific heat capacity as N2 shows lower smoke emissions than with N2. Chemical kinetics analysis shows that carbon dioxide may help to reduce NOx and soot by lowering the reaction temperature as well as by changing the concentrations of some radicals or/and species related to soot and NOx formation.

Alcohol fuels that can be produced from cellulose continue to become more widely used in gasoline engines. This research investigated the application of alcohol to diesel engines with the aims of improving the combustion of diesel engines and of utilizing alternative fuels. Two methods were compared, a method in which alcohol is injected into the air intake system and a method in which alcohol is blended in advance into the diesel fuel. Alcohol is an oxygenated fuel and so the amount of soot that is emitted is small. Furthermore, blended fuels have characteristics that help promote mixture formation, which can be expected to reduce the amount of soot even more, such as a low cetane number, low viscosity, low surface tension, and a low boiling point. Ethanol has a strong moisture-absorption attribute and separates easily when mixed with diesel fuel. Therefore, 1-butanol was used since it possesses a strong hydrophobic attribute and does not separate easily.

This research investigates the influences of the injection timing, injection pressure, and compression ratio on the combustion and exhaust emissions in a single cylinder 1.0 L DI diesel engine operating with ultra-high EGR. Longer ignition delays due to either advancing or retarding the injection timing reduced the smoke emissions, but advancing the injection timing has the advantages of maintaining the thermal efficiency and preventing misfiring. Smokeless combustion is realized with an intake oxygen content of only 9-10% regardless of the injection pressure. Reduction in the compression ratio is effective to reduce the in-cylinder temperature and increase the ignition delay as well as to expand the smokeless combustion range in terms of EGR and IMEP. However, the thermal efficiency deteriorates with excessively low compression ratios.

Because of recent advances in steering control technology, steer-by-wire systems have continued to become more realistic. The principal issue for these steer-by-wire systems is considered to be promoting reliability through the construction of a design concept that can be utilized appropriately by drivers. This paper first describes the flow between the concept and system structure, and proposes a steer-by-wire system with a mechanical backup mechanism as one possibility. This paper also describes an investigation into its potential advantages using an experimental vehicle installed with the proposed system structure. The potential advantages of steer-by-wire are improved vehicle driving performance, vehicle maneuverability, and the feasibility of innovative packaging and design. In order to make improved maneuverability and design innovations compatible, it is critical to achieve steering characteristics that require little maneuvering angle.

To prevent global warming, many countries are making efforts to reduce CO2 emissions toward achieving 2050 carbon neutrality. In order to reduce CO2 concentration quickly, in addition to spread of renewable energy and expansion of BEV, it is also important to reduce CO2 emissions by improving thermal efficiency of ICE (internal combustion engine) and utilizing carbon neutral fuels such as synthetic fuels and biofuels. It is well known that lean burn is an effective technology to increase thermal efficiency of engine highly. However, since NOx emission from lean burn engine cannot be reduced with three-way catalyst, there have been issues such as complicated system configuration due to the addition of NOx reduction catalyst or limiting lean operation to narrow engine speed and load in order to meet emission regulation of each country.

Due to new CO2 regulations and increasing demand for improved fuel economy, reducing aerodynamic drag has become more critical. Aerodynamic drag at the rear of the vehicle accounts for approximately 40% of overall aerodynamic drag due to low base pressure in the wake region. Many studies have focused on the wake region structure and shown that drag reduction modifications such as boattailing the rear end and sharpening the rear edges of the vehicle are effective. Despite optimization using such modifications, recent improvements in the aerodynamic drag coefficient (Cd) seem to have plateaued. One reason for this is the fact that vehicle design is oriented toward style and practicality. Hence, maintaining flexibility of design is crucial to the development of further drag reduction modifications. The purpose of this study was to devise a modification to reduce rear drag without imposing additional design restrictions on the upper body.