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To comply with increasingly strict emission regulations, diesel vehicles are equipped with Diesel Particulate Filters (DPF) to capture fine particulate matter (PM) from exhaust gas. However, due to the limited capacity of DPF to capture soot, periodic regeneration processing is required to burn it off. The ash created by metal-based additives in engine oil accumulates in DPF, leading to issues such as increased regeneration frequency and decreased fuel efficiency. To solve this problem, researchers have developed diesel engine oil with reduced ash content. However, the authors are taking it a step further and developing a diesel engine oil without metal-based detergents and anti-wear additives, for even more significant environmental impact reduction. This paper describes the development of an ashless engine oil with DH-2 performance, the effects of the developed engine oil on DPF, and the results of engine and actual field tests.

A fuel reforming technology using a low temperature oxidation was developed to improve a NOx reduction performance of HC-SCR (Hydrocarbons Selective Catalytic Reduction) system, which does not require urea. The low-temperature oxidization of a diesel fuel in gas phase produces NOx reduction agents with high NOx reduction ability such as aldehydes and ketones. A pre-evaporation-premixing-type reformer was adopted in order to generate a uniform temperature field and a uniform fuel/air premixed gas, and to promote the low temperature oxidation efficiently. As a fundamental study, elementary reaction analysis for n-hexadecane/air premixtures was carried out to investigate the suitable reformer temperature and fuel/air equivalence ratio for generation of oxygenated hydrocarbons. It was found that the reforming efficiency was highest at the reforming temperature around 623 to 673K, and aldehydes and ketones were produced.

An on board burner that enables DPF regeneration even when an engine is at standstill has been researched. By employing pre evaporative combustion with a wick burner, miniaturization of the burner system was successfully accomplished as well as stable ignition and combustion. Total heat necessary for DPF regeneration was reduced in comparison to the active DPF regeneration by means of engine control and an oxidation catalyst. Uneven temperature distribution in DPF and excessive temperature rise, which had been recognized as issues in the regeneration of a DPF while engine is at standstill, were solved by increase of combustion air amount and multi-step control of regeneration temperature and reliable regeneration was accomplished.

The change in the smoke emissions from a diesel engine with the shapes of the combustion chamber and the in-cylinder density was investigated with focuses on the mixing and the soot formation in a spray flame. First, the mixing of the fuel and air between the nozzle exit and the set-off length was used as an indicator for the formation of soot. Although this indicator can explain the influence of the density, it cannot explain the changes in the smoke emissions with a change in the shape of the combustion chamber. Next, by focusing on the soot distribution in a quasi-steady-state spray flame, the soot formed in the high-density condition of an optically accessible engine was investigated by applying two-color method. These results showed that the positional relationship between the maximum soot amount position and the flame impinging position can be a major influence on the smoke emissions.

The deposition of ash derived from engine oil on the surface of diesel particle filters (DPF) has recently been reported to degrade the performance of the DPF. It is generally known that phosphorus in engine oil is adsorbed on the surface of an automotive exhaust catalyst, reducing the performance of the catalyst. Thus, the amounts of ash and phosphorus in engine oil have been decreased. We have developed a non-phosphorus, non-ash engine oil (NPNA) that does not contain metal-based detergents or zinc dialkyldithiophosphate (ZnDTP). Various engine tests were performed, and we confirmed that under normal running conditions, the NPNA oil had a sufficiently high piston detergency and wear resistance-two important requirements for engine oil-to meet current American and Japanese standards. However, the piston detergency of NPNA required further improvement when engine running conditions were more severe.

The correlation between newly approved EN 15751 and the internal diesel injector deposits (IDID) due to fuel oxidative deterioration has not been made clear. In the present research, the Rancimat method was slightly modified to research the relationship between fuel oxidative deterioration and the deterioration products generated from the fuel. After heating fuel at 120 to 150°C for a set period, insoluble deterioration products (IDID-like substances) were generated and their weights were measured. At the same time, the shifts of the conductivity in trap water were analyzed from a new perspective, and its relationship with the deterioration products was investigated. At 120°C and 130°C, conductivity rising rates after the inflection point (this set of data represents the rate of organic acid generation in the fuel, and we named “Oxidation rate”) exhibited a strong correlation with the quantity of deterioration products.

Modern formulation in a wide variety of lubricants including engine oils and transmission fluids is designed to control friction through film-forming tribochemical reactions induced by the functional additives mixtures. Although many cases on the synergistic or antagonistic effects of additives on friction have been reported, their mechanisms are poorly understood. This study focused on the influences of metallic detergents on tribochemical reactions. We examined the mechanical properties of detergent-containing lubricants confined at a single-asperity contact and their contributions to tribochemical phenomena. We found that detergents enlarged the confinement space required for generating repulsive force and shear resistance. This means that these detergents provide steric effects under nanoconfinement at interfacial contacts.

In order to improve the brake thermal efficiency of the engine, such as cooling and friction losses from the theoretical thermal efficiency, it is necessary to minimize various losses. However, it is also essential to consider improvements in theoretical thermal efficiency along with the reduction of the various losses. In an effort to improve the brake thermal efficiency of heavy-duty diesel engines used in commercial vehicles, this research focused on two important factors leading to the engine's theoretical thermal efficiency: the compression ratio and the specific heat ratio. Based on the results of theoretical thermodynamic cycle analyses for the effects of the above two factors, it was predicted that raising the compression ratio from a base engine specification of 17 to 26, and increasing the specific heat ratio would lead to a significant increase in theoretical thermal efficiency.

One issue of downsized and supercharged engines is low-speed pre-ignition (LSPI) that occurs in the low-speed and high-load operating region. One proposed cause of LSPI is the influence of the engine oil and its additives. However, the effect of engine oil additives on pre-ignition and the mechanism involved are still not fully understood. This study investigated the influence of engine oil additives on abnormal combustion in a spark-ignition engine. A four-stroke air-cooled single-cylinder engine with a side valve arrangement was used in conducting combustion experiments. The research methods used were in-cylinder pressure analysis, in-cylinder visualization and absorption spectroscopic analysis. Engine oil additives were mixed individually at a fixed concentration into a primary reference fuel with an octane number of 50 and their effect on knocking was investigated.

Recently, deposition of ash derived from engine oil on the surface of a diesel particle filter (DPF) has been reported to worsen the performance of the DPF. It is generally known that phosphorus in engine oil is adsorbed on the surface of an automotive exhaust catalyst and reduces the performance of the catalyst. Thus, the amounts of ash and phosphorus in engine oil have been decreased. We have developed a non-phosphorus and non-ash engine oil (NPNA) that does not contain metal-based detergents and zinc dialkyldithiophosphate (ZnDTP). We performed a performance test for NPNA using an actual engine and reported that the piston detergency and anti-wear performance of NPNA were sufficiently high. However, the piston detergency of NPNA required further improvement when engine running conditions were more severe.

Automobile exhaust gas contains various harmful substances other than carbon dioxide, so exhaust gas post-processing devices have been developed to reduce their environmental load. Engine oil has contributed to the improvement of automobiles' environmental performance due to its excellent fuel-saving and long-drain properties. Recently, the lifetime of an exhaust gas post-processing device has been reported to decrease due to ash and phosphorus in engine oil. We have developed non-phosphorus and non-ash engine oil (NPNA), in which metal-based detergents and zinc dialkyldithiophosphate (ZnDTP) were not contained. We have performed a verification test for NPNA using an actual engine. In a performance test for a diesel particulate filter (DPF), the amount of soot and ash deposited onto a DPF was smaller when NPNA was used than when commercially available engine oil was used.

Wear resistance is the important characteristics of cast iron materials for automobile components. Because the phenomenon of wear is a highly complicated mechanism involving many factors such as surface conditions, chemical reactions with lubricants, metals, and physics, it has not been fully explained. Therefore, it will be necessary to confirm and explain the wear mechanism to develop effective improvements. The purpose of this study was to investigate the structural change behavior and effects of alloying elements when the material top surface becomes worn, in order to improve the wear resistance of cylinder liners and other cast iron materials. For this purpose, several types of prototype materials were produced, and the relationship between components and wear resistance was investigated by using a laser microscope for quantitative observation of the degree of pearlite microstructure fineness.

1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.

Due to increasing demands for further CO2 reduction and tighter exhaust emissions regulations, automakers are increasingly downsizing turbo-charged diesel engines by raising specific power, or adopting low-pressure loop exhaust gas recirculation (LPL-EGR) systems to improve the EGR rate. However, adopting a higher boost pressure to increase the specific power, or introducing hot exhaust gas before the turbocharger compressor with the LPL-EGR system creates higher gas temperatures in the compressor, which results in soot-containing deposits derived from the engine oil in the compressor. This phenomenon causes significant deterioration of turbocharger efficiency. Therefore, countermeasures such as restricting boost pressure or limiting EGR usage in the operational map are necessary to prevent engine performance deterioration. Increasing the gas temperature in the compressor while preventing deposit formation should enable further improvements in fuel consumption and engine power.

Diesel engine has a good fuel economy and high durability and used widely for power source such as heavy duty in the world. On the other hand, it is required to reduce NOx (Nitrogen Oxides) and PM (Particulate Matter) emissions further from diesel exhaust gases to preserve atmosphere. The urea-SCR (Selective Catalytic Reduction) system is the most promising measures to reduce NOx emissions. DPF (Diesel Particulate Filter) system is commercialized for PM reduction. However, in case that a vehicle has a slow speed as an urban area driving, a diesel exhaust temperature is too low to activate SCR catalyst for NOx reduction in diesel emissions. Moreover, the diesel exhaust temperature becomes lower as a future engine has less fuel consumption. The purpose of this study is reduction of NOx emission from a heavy-duty diesel engine using the Urea SCR system at the low temperature.

The study of 10% ethanol blended gasoline (E10 gasoline) utilization has been conducted in the Japan Auto-Oil Program (JATOP). In order to clarify the impact of E10 gasoline on vehicle performances, exhaust emissions, evaporative emissions, driveability and material compatibility have been investigated by using domestic gasoline vehicles including mini motor vehicles which are particular to Japan. The test results reveal that E10 gasoline has no impact on exhaust emissions, engine startup time and acceleration period under the hot start condition, but a slight deterioration is observed in some test cases under the cold start condition using E10 gasolines with 50% distillation temperature (T50) level set to the upper limit of Japanese Industrial Standards (JIS) K 2202. Regarding evaporative emissions, the tested vehicles shows no remarkable increase in the hot soak loss (HSL), diurnal breathing loss (DBL) and running loss (RL) testing with E10 gasolines.

Engine oils normally contain calcium detergents and ZnDTPs to have detergency and antiwear performance. However, it has been recently understood that these additives could deteriorate filter performance in catalyst and DPF. In this background this paper explains the study and the development about new type of engine oil excluding metal detergents and phosphorus compounds. The developed engine oil shows good durability in several JASO engine tests and a fleet test by formulating newly developed additives as substitute for calcium detergents and ZnDTPs.

To reduce NOx emissions from a heavy-duty engine at low exhaust temperature conditions, the plasma-assisted SCR (Selective Catalytic Reduction) system was evaluated. The plasma-assisted SCR system is mainly composed of an ammonia gas supply system and a plasma reactor including a pellet type SCR catalyst. The preliminary test with simulated gases of diesel exhaust showed an improvement in the NOx reduction performance by means of the plasma-assisted SCR system, even below 150°C conditions. Furthermore, NOx reduction ratio was improved up to 77% at 110°C with increase in the catalyst volume. Also NOx emissions from a heavy-duty diesel engine over the transient test mode in Japan (JE05) were reduced by the plasma-assisted SCR system. However, unregulated emissions, e.g., aldehydes, were increased with the plasma environment. This paper reports the advantages and disadvantages of the plasma-assisted SCR system for a heavy-duty diesel engine.

EPA 2010 emissions regulations - currently the strictest standards in the world - place particular emphasis on exhaust gas thermal control technology. The Burner System, a device developed to control exhaust gas temperatures, is the most effective means of raising exhaust gas temperature, as this system can function under any engine conditions, including low engine speed and torque. The Burner System begins operating immediately when the engine is started, activating the Diesel Exhaust Fluid (DEF) - Selective Catalytic Reduction (SCR) System immediately, because the Burner System is active, it enables the diesel particulate filter active regeneration under any engine operating conditions as well. This technical paper reports Burner System (ActiveClean™ Thermal Regenerator) development results.

The U.S. Environmental Protection Agency (EPA) issued new emissions regulations, which came into effect in January, 2010. These EPA 2010 regulations are the most stringent emissions standards in the world, reducing both particulate matter (PM) and nitrogen oxides (NOx) to nearly zero levels. Hino Motors improved upon its previous EPA 2007-compliant engine, developing a new exhaust after-treatment system in which a Diesel Particulate active Reduction System (DPR), a Urea-Selective Catalytic Reduction (SCR) System and a Burner System are employed to meet EPA 2010 emissions regulations for medium duty commercial vehicles. DPR was already developed and utilized to reduce PM to meet EPA 2007 standards, but the Urea-SCR System is newly developed technology used to reduce NOx emissions to comply with EPA2010 emissions regulations. In addition, a Burner System is used to elevate exhaust gas temperatures in order to improve both SCR performance and DPR active Regeneration.