This study computationally investigates the combined effects of EGR and boost pressure on HCCI combustion process for n-heptane under the condition of constant amount of fuel. The computations were conducted using the single-zone model of CHEMKIN-PRO with detailed chemical-kinetics mechanisms for n-heptane from Lawrence Livermore National Laboratory. Contribution matrix on heat release of elementary reactions is employed to better understand underlying mechanisms of EGR and boost pressure on HCCI combustion process by extracting important elementary reactions. Using contribution matrix on heat release of elementary reactions, it is possible to chemically explain the combined effects of EGR and boost pressure on HCCI combustion process.

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The generation mechanism of the deposit which causes EGR valve stick in the Lean combustion was investigated. This deposit is easily generated by cooled environment at the time of transient state. The chemical analysis was conducted in order to check the chemical component which causes the EGR valve stick in this deposit. From the analysis result of emission gas and the deposit, the chemical factor which causes EGR valve stick was able to be found out. In order to check the credibility of this chemical factor, the reappearance examination using a diesel engine was actually done. The rightness of the factor probed in the chemical analysis by reappearance examination was checked. The factor which should be controlled in order to control the deposit carried out based on the above result is introduced.

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A diesel oxidation catalyst (DOC) that oxidizes to convert from NO to NO₂ on platinum plays an important role in a number of diesel exhaust aftertreatment systems. In this study, the quasi-2D DOC model is set up and DOC performance is simulated by parametric sweep of pore diameter, pore porosity of Al₂O₃ which is support materials and platinum density. Therefore, this study aims is to obtain design concept for optimizing performance advances and cost reduction. The results indicate that the increase of macro pore and thickness of the catalyst are favorable to activate oxidation reaction from NO to NO₂.

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In the previous papers, a combustion system which reduces emissions, noise and fuel consumption using premixed charge compression ignition (PCCI) with split injection of fuel was reported. The keys of this combustion system are the timing and amount of the second injection. In this paper, in-cylinder visualizations and numerical simulations showed that the oxidation of rich flame is accelerated and the soot formation in the near nozzle region is inhibited under the best second injection timing condition with an adequate injection interval. Combustion noise spectra analysis found that a noise canceling occurs between two peaks of pressure rise rate.

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The urea SCR system is a major diesel NOx aftertreatment system. An ammonia slip catalyst (ASC) is located downstream of the SCR system to remove ammonia slipping from it, resulting in forming N₂O having a significantly high global warming potential. Thus, we adopted dual-layered ASCs to identify how N₂O is formed in the oxidation layer and how Zeolite layer thickness effects NH₃ to N₂O conversion characteristics. Engine tests and numerical simulations were conducted. The results show that Zeolite has a supplemental effect of reducing NOx and that an reduction in N₂O formation is possible by increasing zeolite layer thickness while NH₃ conversion is decreased. Thus, it is confirmed that zeolite layer thickness should be optimized to reduce these two emissions.

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Air-Fuel Ratio Sensor is requested high response. To improve the high frequency response of A/F Sensor, we clarified the necessity for the improvement of Diffusion layer and Catalyst layer in the sensing element by the sensor model simulator. As a result, the high frequency response was expanded twice by the sensor that optimized Diffusion layer and Catalyst layer.

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In the present study, the effect of butanol blend fuel on soot reduction was investigated in a diesel engine theoretically as well as experimentally. The concept of the threshold sooting index (TSI), which has been proposed as the sooting tendency in fuel flames, was incorporated into the soot formation model in KIVA-3V code. The soot emission trend obtained in the experiments was clearly shown in the present simulation by considering the characteristic TSI values for butanol and gas oil as well as the alcohol blend ratio.

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We developed a HV inverter testing system which can simulate transient vehicle behavior without actual car, engine, transaxle and battery. This testing system became capable of various operating condition, for example wide-open-throttle acceleration, driving at very low speed and so on. It could also carry out a test of operating condition difficult to be duplicated by experimental vehicle and realize various measurements. These results lead to remarkable man-hour reduction.

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In order to spread electric vehicles, those low-pricing and efficiency are indispensable. DC motors are budget prices compared with AC motors, and their control devices are also simple. However, the efficiency of DC motors is inferior to which of AC motors. In this study, DC motor is combined with CVT (Continuously Variable Transmission). CVT has the feature that changes a gear ratio continuously. The purpose of this study is to control the gear ratio of CVT to drive an electric vehicle with an efficient operation according to conditions of environment and a driver input.

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In order to develop driver support systems that help prevent vehicle-bicycle accidents, it is necessary to examine vehicle and bicycle movements that lead to unsafe driver behavior and subsequent near-miss incidents. In this study, we analyzed near-miss incidents involving left-turning vehicles and bicycles crossing at signalized intersections using the incident database collected with drive recorders. We classified data from 227 incidents into 11 patterns based on characteristics of unsafe driver behavior and bicycle movement. Concerning three major patterns, we investigated both driver observation form and pedal operations which caused near-miss incidents.

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Micro mobility, which is expected as new mobility for elder people, is studied in this paper. Micro mobility has two categories which are personal mobility and two seaters mobility. In Japan, personal mobility is called mini-car. In first report, mini-car accidents using traffic accident data were analyzed. In this report, full-wrap frontal barrier crash tests by mini-car were performed. The cabin which was mounted on the platform keeps enough space for passenger safety after frontal crash. However, the upper body of driver moved to front, and the face and chest were hit steering handle. Because the shoulder anchor of seat belt moved to front due to deformation of B-pillars. The average height of force (AHOF) was measured via multiple load cells on the barrier. The AHOF is lower than average of passenger vehicles. This result means that mini-car has a risk of under-ride at head-on-collision with passenger vehicle.

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Shock waveforms were investigated by considering the frequency response of undamped acceleration transducers in primary vibration calibration. For the purpose, the sensitivity and phase delay from 100 Hz to 5 kHz were calibrated in compliance with ISO 16063-11. Then, three shock waveforms with different pulse width and a peak acceleration 1000 m/s² were evaluated to check the effect of the shock waveforms by the relative frequency response. As the results, the shorter the shock was, the higher the peak acceleration increased. Also, the linearity was evaluated in shock calibration from 1000 m/s² to 5000 m/s², and the sensitivity dependence on acceleration level was constant.

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Our previous report indicated the typical unsafe behavior of elderly drivers when entering intersections without the right of way. This study focused two situations: the first one was driving into the intersection with a road mirror and the second one was driving into the intersection where a lot of cars were crossing. Driving experiments revealed that ignoring the road mirror soon after crossing the stop line and delay in stop timing were two major causes of interference with the oncoming traffic. The experiments also showed that some elderly drivers failed to estimate the proper gap especially under the pressured conditions.

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Recently automatic wiper is equipped widely on vehicle. It can provide clear visibility to the driver but cause troublesome when the wiper do not work properly especially at drizzling rain because the rain sensor detect only adhesion rate of raindrop on the windshield. In this paper, we investigated the mechanism of driver’s control of windshield wiper by using driving simulator. We found that the major factors that influence on driver’s control of windshield wiper are increase in adhesion number, size and adhesion position of the raindrop. We also found that driver’s control of windshield wiper is caused by not only from decrease of visibility but also from attention attracted by raindrops (visual attention).

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The goal of this study is to build a system to prevent a driver from becoming a dangerous state such as a drowsy driving by detecting and resolving a driver’s absentminded state and drowsiness using vehicle equipments. In experiment 1, we have developed detection algorithm using vehicle speed and steering angle, and verified the accuracy of the algorithm using 34 driving data measured under the actual driving environment. As a result, detection accuracy was 82%. In experiment 2, we compared five-sense stimulation including display image change, sound change and air blowing, and active coping including utterance, exercise and finger movement. The effect of resolution methods was evaluated through subjective evaluation and facial expression rating score. As a result, it was suggested that the methods based on active coping had higher effect than the methods based on five senses.

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To realize smooth and eco traffic, it is effective to make every driver keep an ideal speed. This paper proposes a speed guidance system which enables drivers to drive at an ideal speed, utilizing the information presentation method the authors proposed in the previous paper. The information presentation method informs a driver of maneuvers of the accelerator pedal by using periodic knocks on the accelerator pedal. As a result of experiments to make subject drivers keep an ideal speed on a highway using driving simulator, the proposed system is proved to be effective.

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The present study was conducted to clarify the characteristics of human motion and perception, and to develop a force perception model relating to vehicle operation. The results highlighted three points in particular: (1) with steering wheel forward and reverse operation, the tendencies of reaction force perception and related variations depend on the amplitude of the reaction force; (2) perception is affected by reaction force with individual postures and posture changes; and (3) a subjective human force perception model can be derived from the experimental results, which shows a clear correlation with measured values in steering wheel forward and reverse operation.

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Although a trailer is not a self-propelled vehicle, it is treated like a truck or passenger car under the Road Transport Vehicle Act in Japan. So by law, a trailer is required to have a vehicle registration, along with periodic and daily inspections. Trailers usually have a larger body size and loading capacity than general cargo trucks. Due to these characteristics, trailer frames and components often develop damage related to metal fatigue which is caused by the stresses produced by both forward and turning motions. When trailers are used for more than 10 years, deterioration (corrosion and rust) can worsen, and if not maintained correctly, this can lead to serious accidents. In order to secure trailer transportation safety, this paper recommends that special maintenance methods should be used for trailers that have been in use for longer than 10 years.

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True stress-strain curves of SPR and base materials were estimated by dual indenter method, and pre-strain levels of SPR and base materials were determined by the estimated stress-strain curves. Pre-strained specimens were prepared and conducted fatigue tests. Stress distribution of the SPR and its joints were analyzed by FEM, and fatigue strengths of SPR itself and SPR joints were correlated. Next, fatigue tests of base materials were conducted for 0 % and 10 % pre-strained materials. The results demonstrated that the fatigue strengths became similar by the pre-strain for different strength base materials.

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For the future navigation systems and driver assistant systems, a precise and robust localization technology that takes advantage of entire circumference fish-eye cameras and uses particle-filter with two likelihoods, is proposed. The effectiveness of this localization technology has been verified by experiments.

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Large freight trucks and the semi-trailers are required to be able to carry as much cargo as possible at one time. So it is necessary to reduce vehicle weight in order to maximize pay load within gross vehicle weight which is set by laws and regulations in Japan. When designing trucks, various kinds of material such as steel, aluminum, and resin and other. If these materials are used properly, it can significantly make vehicle lighter which not only contribute to increase fuel efficiency but also add value to the product. However it is important to consider environmental factor which is recycling of material to respond market’s demand. This report considers the transition of the materials used for the trucks and trailers by the structural change of the body.

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