The authors investigated the accumulation and oxidization behavior of particulate matter (PM) in a Diesel Particulate Filter (DPF) wall using a newly developed visualization technique. Observations were performed on the conditions required for the PM accumulation and PM forced oxidation processes in test pieces cut from the cordierite DPF. Some notable behaviors were established. In the earlier period of the accumulation process, the PM penetrated the DPF wall, and in the PM forced oxidation process, the PM in the wall was first oxidized, and the nearest part of the PM cake layer to the DPF wall becomes selectively oxidized. The activation energy of PM oxidation that is located adjacent to catalyses in the DPF was calculated from these observation results. The value of the activation energy was close to that found by former researchers.

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It should be common sense to be concerned for reducing amount of platinum group metals, usage in three-way catalyst over keeping its performance due to tough atmosphere for catalytic reactions. From recent study of thermal deterioration in both palladium catalyst and rhodium one, following were found: 1) PdO should be key to avoid Pd sintering and uniformly dispersed barium on alumina is effective to maintain PdO phase. 2) To disperse Pd particle in 3-dimentional nano-structure by porous alumina has also big impact on inhibition of Pd sintering. 3) The encapsulated structure of cerium-zirconium-Rh by lanthanum-alumina leads to suppress Rh sintering.

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Most of the recent clean diesel engines are generally equipped with exhaust gas recirculation (EGR) technology in order to meet the strict criteria of NOx emission regulations. In the field of emission control, accurate and fast transient EGR ratio operation is becoming very critical. In this study, a transient EGR analyzer has been developed and evaluated to confirm the advantage of the transient EGR analyzer by comparing it to a conventional exhaust gas analyzer system. A faster response has been observed from the transient EGR analyzer without significant transient error during transient test cycles. Furthermore, there was a high correlation between the EGR valve behavior implemented and the EGR ratio measured by the transient EGR analyzer. These results show the advantages of the transient EGR analyzer when measuring the EGR ratio during the transient cycle. Additionally, using the response time of measured actual exhaust gas, the gas transition time of the engine EGR system was obtained by z-transformation.

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In general, diesel engines (DE) have an advantage in thermal efficiency by comparison with gasoline engines. In recent years, DE is getting cleaner with NOx aftertreatment devices such as LNT and SCR in addition to common rails and Diesel Particulate Filter. On the other hand, due to the increase of fuel efficiency-oriented consumers worldwide, further improvement of fuel consumption is expected to DE. Under the circumstance, the authors developed and introduced New Generation Clean DE into the Japanese market as SUV segment. A serial sequential 2-stage turbocharger system was employed to a turbocharging technology in support of low compression ratio to achieve ideal combustion. This enabled the engine to achieve good driving pleasure, high fuel efficiency, and compliance with regulations without NOx aftertreatments.

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A new combustion concept for direct injection spark ignition gasoline engine was developed. Intake tumble flow is accelerated by a new fan-shaped spray jet, mixture homogeneity and combustion speed is improved. By fine atomization and low penetration of the spray, both oil dilution and particulate matter emission, which represent major issues in the concept, are reduced. It also achieves a good performance in stratified combustion for catalyst heating.

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The aim of this work is to investigate the possibility of heat insulation by “Temperature Swing”, that is temperature fluctuation, in combustion chamber walls coated with low-heat-conductivity and low-heat-capacity materials. Based on our calculations, it is clarified that both the prevention of intake air heating and the low heat rejection are successfully possible with the material of appropriate thermo-physical properties. In our preliminary test-piece experiment, it is demonstrated that the surface temperature of the coat with the above-mentioned structure immediately follows the transient gas temperature.

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Recent years have already seen tighter regulation on harmful substances such as NOx, CO and CO₂. In car engines an increasing concern in environmental issues such as air pollution, global warming and petroleum depletion has helped drive researches into various ways. The purpose of this research is the development of a prompt measurement technique which can be applicable to various engine conditions. The tunable diode laser absorption spectroscopy using the hollow fiber has been developed to satisfy above requirements. A sensitive method using tunable UV diode laser absorption spectroscopy was also discussed to detect NOx in exhausts.

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In order to clarify the behavior of reductants in a urea-SCR system, two types of diagnostic techniques were developed: one is for measuring NH₃, and the other is for measuring total-reductants including unreacted urea and isocyanic acid. These techniques were applied to examine the behavior of reductants at the inlet and inside of the SCR catalyst. This revealed that i) urea to NH₃ conversion rates and spatial distributions of reductants at the inlet of the catalyst, and ii) temporal and spatical profiles of urea to NH₃ conversion inside the catalyst.

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Urea-SCR systems are getting a lot of attention as a promising NOx reduction technology for diesel engines. We develop an urea-SCR catalytic reaction model with detailed surface chemistry and urea decomposition reactions on the catalyst. The validity of the urea decomposition reaction model is confirmed by the experimental data which is directly measured inside the catalyst converter. This model can successfully predict gas emissions (such as NOx and NH₃) for urea-SCR converters under various vehicle test conditions.

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Usually the transmission efficiency of hypoid gear is much lower than helical gear because of its large mesh loss between tooth flanks of pinion and crown gears. Moreover, the friction loss is also remarkable for automotive application since the pinion gear is overhang-supported by preloaded bearings to receive big axial force. Therefore, the improvement of efficiency is an old subject and becomes more important for current fuel economy. This study directly measured the transmitting loss torques of each part of hypoid gear by using a gearbox test rig, and reconsidered the famous Coleman’s efficiency formula of hypoid gear. As a result, the limit of Coleman’s formula is clarified, and several attempts for design high efficiency hypoid gear are tried and practically applied to new developed CVT transmission.

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In this report, I will discuss the target vehicle dynamics in low speed region. We discuss the effects which variation between body slip angle and yaw velocity affects driver’s sensitivity or evaluation in the low speed cornering situation. Firstly maneuverability test for low speed cornering was examined by front and rear steering vehicle. The result says that the driver can control without discomfort for the higher yaw velocity gain, the smaller outward body slip angle is generated at the low speed cornering. Next I will explain the characteristics by the analysis of the driver-vehicle closed loop system. I assumed that driver recognizes the angle between vehicle heading direction and gaze point as the gaze angle and steers based on the first order look-ahead driver model. Consequently the discussion about the gain of the driver model in the human-vehicle closed loop system revealed that the effect which variation between body slip angle and yaw velocity affects driver’s sensitivity or evaluation for vehicle cornering motion.

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Magic Formula model, FEM tire model and Fiala model are principal tire models which have been developed in the past. Models for four-wheeled vehicle have been developed by these tire models. Though models for motorcycle have been developed by Magic Formula and FEM model, Fiala model for motorcycle have not been developed. Hence, at present it is not easy that we use Fiala model for use in motorcycle. And so we have extended Fiala model for four-wheeled vehilcle tire to motorcycle tire. In this paper, we validated extended Fiala model with FEM tire model.

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This paper describes a parametric-free optimization method for designing the smooth optimal free-form of automotive shell structures. A stiffness design problem is formulated as distributed-parameter shape optimization problem, and the sensitivity function is derived under the assumptions that the shell is varied in the normal direction to the surface and the thickness is constant. With this method, optimal global and local curvature distribution involving beads can be created without any shape parameterization. The validity and practical utility were verified through several design examples. It was also confirmed the obtained structures became ideal membrane-carrying structures.

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By using numerical analysis, the effect of installation position of concave geometry in cross section of thin-walled polygonal shell member on progressive plastic buckling was studied to verify the robustness of a design scheme for Crash Boxes with high crash energy absorption. Analytical results showed that plastic buckling behavior is depended upon the width of plane, W_p between ridgelines in cross section without relations of the installation position of concave geometry. In summarized, the robustness of a design scheme of installing concave geometry in cross section to control W_p was verified to ensure high energy absorption by stable plastic buckling.

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ISO 2631-1, which defines methods for the measurement and evaluation of human exposure to whole-body vibration, describes factors contributing to the discomfort from vibration. However, investigations of the effect of sound and visual images on whole-body vibration are necessary to evaluate ride comfort truly. Then, we developed a new driving simulator to realize virtual driving easily. This paper reports the psychometric experiments with various conditions of vibration and audiovisual stimulation. For evaluation of whole-body vibration, we used the category judgment method. We discussed the relationship between the stimulation condition and subjects' assessment.

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This paper evaluates variability of experimentally measured Frequency Response Function (FRF). The FRF measurements are repeated with and without resetting the accelerometer and road cell. The difference shows the variability due to the sensor set-up for the experiment. After that, we discuss the effect of FRF variation on identified forces in Transfer Path Analysis, which is a key technology for solving the noise and vibration problems. The Matrix Inversion Method is used for force identification. The effect of the number of accelerometers on the variation of the identified forces is examined by changing the number of adopted sensors. It is turned out that the variation of identified force becomes smaller as the number of sensors is increased.

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The purpose of this work is to measure discomfort of driver and bicycle when they pass roadway simultaneously and make few suggestions for composition of bicycle lane. First, we researched mental barrier for bicycle users when they pass roadways by questionnaires and counting of passing position of bicycle. Second, we conducted experiments by means of driving simulator to measure driver’s mental load. We also made eye measurements of side interval between actual car and bicycle. We found cars and bicycles feel discomfort when side interval is less than 1.5m. This discomfort disappeared when side interval was more than 2.5m.

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Traffic accidents are the accident due to negligence. However, there is possibility of unavoidable accidents. This paper treats unavoidable accidents taking the crossing between left-turning vehicle and bicycle on the pedestrian crossing as an example. Bicycles are at high risk of accidents due to its speed by comparison with pedestrians. The points where vehicle drivers become aware of a bicycle are clarified by experiments. The time that vehicles require to stop at ultralow speed are analyzed by experiments. The dangerousness of crossing of left-turning vehicle and bicycle on the pedestrian crossing is studied using those experimental data.

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More safety applications will use the vehicle's own position in the near future. It is very important for those position-based applications to know whether the positioning is reliable or not. The conventional kalman filter is good at estimating the positioning error based on gaussian measurement noise. However, GPS multipath is hard to estimate since it depends on nearby buildings in urban areas. We developed an accurate positioning system and its function to estimate the reliability of the positioning result. We tested the proposed method in an urban area and the estimated reliability matched well with the positioning accuracy..

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A new vehicular body structure with a seat integrated load-path was proposed. The structure composes a load-path from the B-pillar to the floor of the vehicle, which supports crash load applied to the B-pillar during side impacts. By using an experimental vehicle in which the structure was incorporated, a quasi-static loading test was conducted. The results successfully indicated that the composed new load-path effectively transferred applied load.

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A pedestrian accident has the great portion of number of the fatal traffic accident. In order to reduce the fatal traffic accidents from now on, reduction of a pedestrian accident is important. In this research, the change of the pedestrian visibility by a headlight in various traffic environment was analyzed by the subject experiment. We were able to clarify visibility when the aged driver looked at the pedestrian at nighttime.

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The objective of this study is to verify the effects of a motorized seat belt on dummy kinematics and responses in pre-crash sled system with pre-impact braking. For this purpose, the sled test with pre-impact braking was conducted by using Hybrid III with a modified lumbar. It was confirmed that the motorized seat belt decreases the chest movement not only during the pre-impact braking phase but also in the collision phase compared to the case of a current seat belt. Moreover, the motorized seat belt could reduce chest acceleration due to the improvement of initial restraint effect.

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Recently, information for drivers are dramatically increasing in accordance with increased number of new functions such as IT/ITS and ECO driving support. When drivers acquire necessary information, they have to select it from the complex visual environments. Previous researches have demonstrated that observers tend to focus their attention to a certain surface and easily neglect the information located on the different surface, yielding higher performance in visual search. In the present study, we investigated performance of visual search, when the information were displayed on different surfaces. It was found that a meter with information displaying located in depth improved the performance in visual search.

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This research investigated a method for providing the auditory information to drivers in active safety vehicles. Our first report clarified that it was difficult for elderly drivers to segregate the voice signal from background noise and acquire the multiple auditory items in a short time. Therefore the experiments were conducted to examine whether they could capture the voice information while listening to the radio news. As results, the radio listening hindered the information acquisition regardless of whether participants were listening to news in a careful or uncareful manner. It was also revealed that the female voices were easer to discriminate than the male voices.

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It is investigated that the soak conditions have an effect on the amount of N₂O in exhaust of gasoline vehicles at starting. As a result, it is found that the amount of N₂O increases by the effect of the short time soak. Next, by the factual survey of the vehicle usage condition, it is found that the vehicles less than 2 hours soak is more than 40 % of the whole business vehicles. With these results, it is indicated that the operation of the short time soak test is necessary for the evaluation of the green-house-gas emission.

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Tail pipe emissions and evaporative emissions were measured from 4 passenger cars which are conformed most recent exhaust gas emission regulations. The VOC tailpipe emissions from three vehicles were slightly high compared with their certification results. The evaporative emissions were well below from the regulated value. The total amount of VOC emission from cars was estimated from the experimental results and questionnaires for car users about the mean travel distance in a year. As for results, 53 % in the total VOC emissions were emitted by the evaporative emissions. The estimated emissions of the VOC from the gasoline vehicles were almost 3 % in total VOC emission in Japanese society.

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WTW (Well-to-Wheel) assessment has been used to comprehend environmental impacts from vehicles. Especially, WTW assessment of FCEV (Fuel Cell Electric Vehicle), whose fuel is hydrogen, has been attracting attention because hydrogen has many supply paths. In this paper, we constructed a formula mainly in Tank-to-Wheel process, which can evaluate CO₂ emissions in driving stage of FCEV. Furthermore, in order to clarify the influence of traffic conditions, CO₂ emissions from all vehicles in Fukuoka prefecture were evaluated in WTW process with consideration for not only FCEV penetration ratio and hydrogen supply paths, but also vehicle speed and traffic volume.

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Histories of PM and PN, which is regulated in Europe, over DPF regeneration period were measured from the most recent HD vehicle. PM exhibited a slight high emission during the regeneration. PN with the regeneration cycle was quite high and reduced drastically as the test cycles proceeded.􀀃 The certification value of a vehicle with periodically DPF in EU is the average in whole the regeneration period, and 16 % of estimated certification PM from this study was derived from the cycle with the regeneration. 99 % of estimated PN certification value is derived from 3 cycles from the regeneration. The real time observation of PN indicates that the high emissions during and after the regeneration arose by the drop of filtering efficiency due to decreasing particles in DPF by the oxidation.

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This study demonstrates possible energy-saving effect in case longitudinal control method based on local traffic states for energy conservation is used. If eco-driving is realized using longitudinal control for energy conservation, the control needs to observe various traffic states' information and reduce wasteful acceleration and deceleration. This study reports simulation evaluations of possible energy-saving effect using an algorithm that uses an idealized velocity pattern based on information such as Vehicles and signals, and optimal control for longitudinal using the eco-driving pattern.

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In Japan, a new project for reducing CO₂, called "Energy ITS project", has started since 2008 by NEDO (New Energy and Industrial Technology Development Organization). In this project, an autonomous platooning system of heavy-duty trucks is developed to reduce the amount of CO₂ emission. This project assumes that trucks run in mixed-traffic, where there are various dangerous factors such as a broken-down car, an obstacle and so on. Therefore, the technology of autonomous lane changing for safe platooning is required. In this paper, the method of autonomous lane changing based on path following is proposed and confirmed to be very effective by experiments.

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In order to realize an accurate and robust positioning system, the precise trajectory estimation is necessary. GPS-Doppler, which can estimate accurate vehicle heading, is one of the most effective approaches to the precise trajectory estimation. However in urban areas, where only a few satellites can be observed, the heading estimation using GPS-Doppler can’t work as it does in suburban areas. In this paper, time-series GPS-Doppler and INS (Inertial Navigation System) are tightly coupled in order to improve robustness in urban areas. With the proposed method, the error of heading estimation has been reduced and the trajectory estimation has been improved in urban areas.

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Local Dynamic Map (LDM) has been studied recently, with which cooperative ITS applications require to manage information based on objects such as vehicles, other objects, and roads. In LDM, information on a map are divided and layered into every feature. Although requirements of transmission delay differ in each layer of the defined map data, the current network technologies do not consider the situation and the transmission delay is increased. In this paper, we propose an efficient transmission method to approach the delay problem for all the transmission data with the increased data volume by using the position relativity of the data receiver automobile in inter vehicle communications and the difference of each layer’s characteristics and transmitting them, high-urgent data should be transferred as quick as possible, and even with low-urgent data they can be delayed, but transferred authentically. We also implement priority levels in the transfer data, and fulfill the band frequency assignments dynamically. Through the result of the evaluation of high and low vehicle density circumstances, we have confirmed that our proposed method is effective in high vehicle density circumstances.

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