National Traffic Safety and Enviro Laboratory

National City, United States

National Traffic Safety and Enviro Laboratory

National City, United States
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Kobashi Y.,Kanazawa Institute of Technology | Fujimori K.,Kanazawa Institute of Technology | Maekawa H.,Kanazawa Institute of Technology | Kato S.,Kanazawa Institute of Technology | And 2 more authors.
SAE International Journal of Engines | Year: 2011

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel. The results showed a good agreement in terms of spray tip penetration, liquid length, ignition delay and so on, for several kinds of dual-component fuels. Additional investigation into a combustion control methodology using dual-component fuel, which aims to mitigate combustion rate of premixed charge, was performed. Consequently, the feasibility of this approach was confirmed. © 2011 SAE International.


Kobayashi M.,New Ace Institute Co. | Aoyagi Y.,New Ace Institute Co. | Adachi T.,New Ace Institute Co. | Murayama T.,New Ace Institute Co. | And 3 more authors.
SAE Technical Papers | Year: 2011

Reduction of exhaust emissions and BSFC was studied for high pressure, wide range, and high EGR rates in a Super-clean Diesel six-cylinder heavy duty engine. The GVW 25-ton vehicle has 10.52 L engine displacement, with maximum power of 300 kW and maximum torque of 1842 Nm. The engine is equipped with high-pressure fuel injection of a 200 MPa level common-rail system. A variable geometry turbocharger (VGT) was newly designed. The maximum pressure ratio of the compressor is about twice that of the previous design: 2.5. Additionally, wide range and a high EGR rate are achieved by high pressure-loop EGR (HP-EGR) and low pressure-loop EGR (LP-EGR) with described VGT and high-pressure fuel injection. The HP-EGR can reduce NOx concentrations in the exhaust pipe, but the high EGR rate worsens smoke. The HP-EGR system layout has an important shortcoming: it has great differences of the intake EGR gas amount into each cylinder, worsens smoke. The system layout can eliminate large differences of intake EGR gas amounts into each cylinder. The improved HP-EGR system layout achieves a wide range and high EGR more than the previous system. For engine speed of 1200 rpm and 40% load (BMEP0.83 MPa), the combined EGR of HP-EGR and LP-EGR can increase about twice EGR rate compared with the case of HP-EGR only and improve NOx to around half without BSFC deterioration. This system was evaluated practically to improve exhaust emissions in both steady-state and transient test conditions. Finally, the super-clean diesel engine is used with this system and checked experimentally using the JE05 transient test mode to meet the target performance. Copyright © 2011 SAE International.


Mizushima N.,National Traffic Safety and Enviro Laboratory | Murata Y.,Waseda University | Suzuki H.,National Traffic Safety and Enviro Laboratory | Ishii H.,National Traffic Safety and Enviro Laboratory | And 2 more authors.
SAE International Journal of Fuels and Lubricants | Year: 2010

The use of biomass fuels for vehicles has been a focus of attention all over the world in terms of prevention of global warming, effective utilization of resources and local revitalization. For the purpose of beneficial use of unused biomass resources, the movement of the use of bioethanol and biodiesel made from them has spread in Japan. In Japan, biodiesel is mainly made from waste cooking oil collected by local communities or governments, and in termsof local production for local consumption, it is used as neat fuel (100% biofuel) or mixed with diesel fuel in high concentration for the vehicles. On the other hand, extremely low emission level must be kept for not only gasoline vehicles but also diesel vehicles in the post new long-term regulation implemented from 2009 in Japan. It is necessary for diesel vehicles to equip an advanced type of aftertreatment such as Urea-Selective Catalytic Reduction (SCR) system or lean NOx trap (LNT) catalyst system in order to comply with this regulation. In this study, engine bench tests were conducted to understand the emission characteristics in the use of high concentration of biodiesel for an engine system with the urea-SCR system which is expected to be equipped for a lot of heavy-duty vehicles in the near future. The results indicated that NOx emission in biodiesel operation increased compared with that in conventional diesel operation under Japanese JE05 mode test. This is because of the NOx emission increasing in the engine out and the NOx reduction efficiency decreasing in the urea-SCR system. Especially, B100 (Neat biodiesel) increased NOx emission over the New Long-Term regulation limit, even though this engine system complied with the new long-term regulation level enough. This was mainly affected by the decrease of NOx reduction efficiency in urea-SCR system due to the decrease of NO2 /NOx ratio at the inlet of urea-SCR. The factor of the decrease in NO2 /NOx ratio was considered to be the decrease in NO2 concentration derived from thereduction of engine-out NO 2 emission and the deterioration of oxidizability of diesel oxide catalyst (DOC). As for the deterioration of oxidizability of DOC, it was thought to be due to the decrease in exhaust gas temperature, catalyst poisoning and reduction action by SOF adhered in DOC. Therefore, it was necessary to improve oxidizability of DOC in order to decrease NOx emissions. © 2010 SAE International.


Osada H.,New Ace Institute Co Ltd. | Aoyagi Y.,New Ace Institute Co Ltd. | Shimada K.,New Ace Institute Co Ltd. | Goto Y.,National Traffic Safety And Enviro Laboratory | Suzuki H.,National Traffic Safety And Enviro Laboratory
SAE Technical Papers | Year: 2010

For reducing NOx emissions, EGR is effective, but an excessive EGR rate causes the deterioration of smoke emission. Here, we have defined the EGR rate before the smoke emission deterioration while the EGR rate is increasing as the limiting EGR rate. In this study, the high rate of EGR is demonstrated to reduce BSNOx. The adapted methods are a high fuel injection pressure such as 200 MPa, a high boost pressure as 451.3 kPa at 2 MPa BMEP, and the air intake port that maintains a high air flow rate so as to achieve low exhaust emissions. Furthermore, for withstanding 2 MPa BMEP of engine load and high boosting, a ductile cast iron (FCD) piston was used. As the final effect, the installations of the new air intake port increased the limiting EGR rate by 5%, and fuel injection pressure of 200 MPa raised the limiting EGR rate by an additional 5%. By the demonstration of increasing boost pressure to 450 kPa from 400 kPa, the limiting EGR rate was achieved to 50%. At the same time, BSNOx was reduced to 1.0 g/kWh from 3.5 g/kWh at 2 MPa BMEP with no increase in smoke emission and particulate matter (PM). The technologies developed in this study are not only to reduce exhaust emissions but also useful and available to improve brake-specific fuel consumption for both single-cylinder and multi-cylinder heavy duty diesel engines. Copyright © 2010 SAE International.


Naganuma K.,Tokyo City University | Takagi Y.,Tokyo City University | Kawamura A.,National Traffic Safety and Enviro Laboratory | Sato Y.,National Traffic Safety and Enviro Laboratory
SAE Technical Papers | Year: 2010

Hydrogen engines are required to provide high thermal efficiency and low nitrogen oxide (NO X) emissions. There are many possible combinations of injection timing, ignition timing, lambda and EGR rate that can be used in a direct-injection system for achieving such performance. In this study, NO X emissions of natural aspirated 4 cylinders engine with management strategies involving the injection timing, ignition timing, lambda and the EGR rate were evaluated under a Japanese JE05 emissions test cycle. Finally, the paper projects the potential of direct injection hydrogen engine for obtaining high output power and attaining low NO X emissions of 0.7 g/kWh under the emission test cycle. Copyright © 2010 SAE International.


Hashimoto M.,New A.C.E. Institute Co. | Aoyagi Y.,New A.C.E. Institute Co. | Kobayashi M.,New A.C.E. Institute Co. | Murayama T.,New A.C.E. Institute Co. | And 2 more authors.
SAE Technical Papers | Year: 2012

Reduction of exhaust emissions and BSFC has been studied using a high boost, a wide range and high-rate EGR in a Super Clean Diesel, six-cylinder heavy duty engine. In the previous single-turbocharging system, the turbocharger was selected to yield maximum torque and power. The selected turbocharger was designed for high boosting, with maximum pressure of about twice that of the current one, using a titanium compressor. However, an important issue arose in this system: avoidance of high boosting at low engine speed. A sequential and series turbo system was proposed to improve the torque at low engine speeds. This turbo system has two turbochargers of different sizes with variable geometry turbines. At low engine speed, the small turbocharger performs most of the work. At medium engine speed, the small turbocharger and large turbocharger mainly work in series. At high engine speed, the small turbocharger does no work at all, but the large turbocharger works mainly using a small turbocharger bypass. The basic engine, with six cylinders in-line and displacement of 10.5 L, is equipped with a high-pressure fuel injection system and a high- and low-pressure loop EGR system for using the high boosting and high EGR rate to reduce BSNOx and PM. Experimentally obtained results show that the sequential and series turbocharging system has 50% higher torque than the conventional, with improved fuel consumption achieved in the low-speed region. Copyright © 2012 SAE International.


Pedersen T.D.,Technical University of Denmark | Schramm J.,Technical University of Denmark | Yanai T.,National Traffic Safety and Enviro Laboratory | Sato Y.,National Traffic Safety and Enviro Laboratory
SAE Technical Papers | Year: 2010

The effects of methanol and EGR on HCCI combustion of dimethyl ether have been tested separately in a diesel engine. The engine was equipped with a common rail injection system which allowed for random injection of DME. The engine could therefore be operated either as a normal DI CI engine or, by advancing the injection timing 360 CAD, as an HCCI engine. The compression ratio of the engine was reduced to 14.5 by enlarging the piston bowls. The engine was operated in HCCI mode with DME at an equivalence ratio of 0.25. To retard the combustion timing, methanol was port fuel injected and the optimum quantity required was determined. The added methanol increased the BMEP by increasing the total heat release and retarding the combustion to after TDC. Engine knock was reduced with increasing quantities of methanol. The highest BMEP was achieved when the equivalence ratio of methanol was around 0.12 at 1000 RPM, and around 0.76 at 1800 RPM. EGR was also used to retarding the timing. With a moderate amount of EGR the effect on the combustion was not notable, but as the equivalence ratio approached unity the combustion was increasingly delayed and the rate of reaction reduced. Engine knock seized entirely as the EGR ratio was increased above 60 %. The BMEP gain was however moderate, since lower cylinder pressures at higher EGR quantities counteracted the positive effects of combustion timing. Copyright © 2010 SAE International.


Morita K.,National Traffic Safety and Enviro Laboratory | Sekine M.,National Traffic Safety and Enviro Laboratory
SAE International Journal of Passenger Cars - Mechanical Systems | Year: 2014

The number of elderly drivers is increasing in Japan and ensuring the safety of elderly drivers is becoming an important issue. The authors previously conducted an analysis of the characteristics of accidents and traffic violations by elderly drivers based on the number of accidents in which they were rear-ended. This method was used in order to exclude the influence of driving frequency. As a result of that analysis, it was found that the likelihood of violations committed by elderly drivers was not particularly higher than in other age groups, while the likelihood of accidents caused by them was higher. The risk of causing an accident was judged to be about two times higher in elderly drivers than in the 35-44 year age group. However, the methodology presupposed that collisions in which a driver is rear-ended are accidents that occur randomly, and that they occur with the same probability in each age group. To verify the results of that study, we attempted a new analytical method that uses the number of stop sign violations, which are considered to occur with the same probability among age groups, as an indicator of driving frequency in place of accidents in which a driver is hit from behind (rear-end collisions). In the new analysis the risk of causing an accident was judged to be 1.24 times higher in elderly drivers than in the 35-44 year age group. In general, the risk of accidents caused by elderly drivers is estimated to be lower than in the previous study. © 2014 SAE International.


Matsui Y.,National Traffic Safety and Enviro Laboratory | Doi T.,Ibaraki Christian University | Oikawa S.,National Traffic Safety and Enviro Laboratory | Ando K.,National Traffic Safety and Enviro Laboratory
SAE International Journal of Transportation Safety | Year: 2013

The number of traffic deaths in Japan was 4,612 in 2011. Looking at the road accident fatalities, it revealed that pedestrians accounted for the highest number in 2011 (1,686, 36.6%). To develop safety countermeasures to decrease the severity of injuries and to reduce the number of deaths in traffic accidents, the detailed characteristics of pedestrian injury in vehicle-to-pedestrian crashes are necessary. The purpose of this study is to understand the scenarios of vehicle accidents in which pedestrians suffer fatal injuries. In the present study, we investigated the characteristics of pedestrian injuries in fatal crashes from accident analyses and compared them to head injury severity levels in impact tests against a road pavement and vehicle contact surfaces. In the accident analyses, we investigated the main body regions injured, that is, the most serious extent of injuries over the whole body of pedestrians by using macro vehicle-pedestrian accident data from database of the Institute for Traffic Accident Research and Data Analysis (ITARDA) of Japan. In comparing the differences in injury frequencies for various body regions between 1999 and 2009, it is noted that the frequencies of pedestrian fatalities due to head injuries were significantly reduced. The result indicated that even though head injuries were the most frequent cause of pedestrian fatalities in traffic accidents, the introduction of pedestrian head protection regulation in Japan in 2005 could be considered effective in reducing fatal head injuries. On the other hand, the frequencies of pedestrian fatalities due to hip injuries increased significantly in sedans, light passenger cars, and light cargo vans. Using the macro accident data in 2009, we investigated the frequency of pedestrian fatalities by gender, age group, vehicle travel speed, and fatal head injuries due to vehicle impacts or road pavement impacts. The results also indicated that the frequencies of female pedestrian fatalities due to hip injuries were significantly higher than those of males. Additionally, the results showed that the frequency of pedestrian fatalities due to hip injuries for the age group of over 65 years was significantly higher than that of the industrial age group (aged 13-59). Focusing on the frequency of pedestrian fatalities due to hip injuries in all age groups, vehicle travel speed appeared likely not to be an extremely important factor in increasing fatal hip injuries. In examining the differences in the frequency of fatal head injuries due to contacts with vehicles or road pavements, it is noted that injury frequency in crashes involving vehicles travelling at high speeds were significantly higher than those at lower speeds for pedestrians over 60 years of age. Focusing on head injury severity levels in impact tests against a road and vehicle surfaces using an adult pedestrian headform impactor, the impacts against a road pavement (HIC 6525) was considered to be more severe than those against vehicle front components with high stiffness (HIC from 2600 to 4032). Copyright © 2013 SAE International.


Morita K.,National Traffic Safety and Enviro Laboratory | Sekine M.,National Traffic Safety and Enviro Laboratory
SAE International Journal of Transportation Safety | Year: 2013

The number of elderly drivers has been increasing in Japan with the rapid progress of the nation's population aging. Securing safety for elderly drivers is an important issue in Japan. In this paper, authors conduct analysis on characteristics of accidents and violations caused by elderly drivers based on data for 2009. As there is a tendency that elderly drivers generally have less opportunity to drive vehicles than younger drivers do, it is necessary to conduct this analysis considering driving frequency when making comparison among age groups. Then, we calculated the normalized ratio (odds ratio) based on the number of rear-ended accidents in order to exclude the influence of driving frequency. As a result of the analysis, it was found that the likelihood of violations committed by elderly drivers was not particularly higher, while the likelihood of accidents caused by them was higher than younger drivers. The risk of causing an accident was judged to be about two times higher in elderly drivers than in the 35-44 year age group. Looking at each type of accident and violation, it is conjectured that they do not purposely disregard traffic signals or commit stop sign violations, but end up having accidents as a result of simply failing to notice them. Copyright © 2013 SAE International and Copyright © 2013 TSAE.

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