Recently, gasoline direct injection (GDI) vehicles are expanding their share of the market. However, different from traditional port fuel injection (PFI) gasoline vehicles, they emit considerably more PM.More and more stringent regulations are setting in the world, even for gasoline vehicles. In Japan, the new regulation for gasoline vehicles will be set in 2020. Then, the filtration system for gasoline soot is needed and a gasoline particulate filter (GPF) should be equipped with GDI vehicles. In this study, by using a lattice Boltzmann method, we simulated the flow through the gasoline particulate filter, corresponding to a so-called ceramic wall-flow filter. To consider the entire cell structure, the simulation was conducted in a two-dimensional domain. We examined the effect of cell length and inflow velocity on flow field, pressure drop and soot deposition.

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To improve the fuel economy, high EGR combustion stability is improved by the addition of hydrogen with fast burning speed in air-fuel mixture. In order to realize on-board hydrogen gas generation, an engine reformer system assembled with a reformer catalyst and a fuel injector on the external EGR line is explored. This report shows the experimental results from multi-cylinder engine experiment with reformer system. Hydrogen gas can be reformed from gasoline fuel at the reformer catalyst. Injection timing, injection times in one cycle and injection spray shape affect reformed Hydrogen concentration and reformer catalyst deterioration. 8pt% increase of combustion stability limit under EGR condition and 3.6% reduction of fuel consumption have been confirmed.

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Previous study showed that promoting evaporation with the mixed fuel was able to realize early evaporation and compact spray, which contributed to cooling loss reduction and thermal efficiency improvement. In this report, nozzle specifications establishing the compact spray were investigated as practical alternatives to mixed fuel application. The effects of this nozzle on thermal efficiency and combustion process were examined by using diesel engine, and its combustion mechanism was revealed by using RCEM (Rapid Compression and Expansion Machine). The results suggested that compact spray contributes to thermal efficiency improvement.

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In the development of a diesel engine applying the downsizing concept, the exhaust performance deteriorates due to the increase of the local rich area of the spray. Therefore, the purpose of this report is to verify the applicability of theory on the spray similarity in the range of scales from small diesel engines for downsizing to diesel engines for passenger cars. As a result, it was suggested that it is possible to simulate the spray similarly in the numerical calculation by using theory on the spray similarity in the range of the similarity scale range .

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This paper proposes a new drive system for a large EV that achieves low cost, large power, and low power consumption by the combination of conventional motors and a simple gearbox. This system is structured to run with one motor in the low-speed range and two motors in the high-speed range, and can switch between the two modes smoothly. Bench tests confirmed that this structure expanded the high-efficiency area of the system. In addition, motor drive systems often have issues with the motor and inverter when the vehicle is stopped on an uphill gradient by accelerator operation only. Hill-stop bench tests confirmed the advantage of the lowest-speed mode of this system. Results found that the thermal load of the inverter is reduced in the lowest-speed mode compared to the one-motor mode, which is equivalent to a single-motor system.

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Motor rotors are generally manufactured by Die-cutting on electrical steel, but Die-cutting causes residual stress and roughness which have influence the fatigue life of the rotor. The acceleration / deceleration test was carried out by using motor, and the rotational fatigue life of the rotor was evaluated by fatigue analysis based on the stress analysis and the fatigue data of the electrical steel. It became clear that the rotational fatigue life of the rotor was able to be calculated accurately by considering the influence of Die-cutting.

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When driving along a straight roadway, a driver regularly makes minute steering adjustments in order to maintain the vehicle’s position within the driving lane. This paper clarifies the quantitative relationship of several steering characteristics in this scenario for accurate line tracing. In this research, the first step was to investigate the driver’s behavior when driving along a straight roadway. Then, a driver model consisting of this behavior was created and underwent driving simulations to hypothesize the relationship between line traceability, steering force and vehicle yaw characteristics. Finally, this hypothesis was tested and verified using an actual driving simulator.

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In this paper, steering torque analysis was pursued to declare a curving mechanism of the motorcycle based on a simple model that was developed by the author. Previous paper described a simple model of a motorcycle, relationship steering angle and rolling angle, and variation of steering characteristics accompanied running velocity. In this paper, from viewpoint of steering torque was analyzed to obtain actual riding impression.

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The modeling method of a joint part between components in an engine is problem for the finite element model, because it is difficult to estimate the stiffness and damping of the joint part. Therefore, the prediction technique for joint dynamic characteristics was proposed by extracting the roughness parameters of surfaces in the jointed component. Next, the device for measuring the dynamic characteristics of joint part was constructed, and the stiffness and damping of the metallic joint were actually estimated by measurement. The stiffness and damping obtained from this actual measurement result have good agreement with the predicted result from this method. Finally, this method was applied to the joint part of engine component, and high prediction accuracy was confirmed.

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Elderly people have lower visual acuity, and hearing ability, compared to those of young people and thus it is more difficult for them to avoid danger. Therefore, vehicles equipped with safety functions should be promoted for safety driving. The Hiroshima Prefectural Police conducts driver safety training sessions for elderly drivers using safe driving support vehicles, with the aim of reducing traffic accidents in Hiroshima Prefecture through the spread of such vehicles. To promote safe-driving support vehicles, it is important to show their beneficial effects. In this study, the author estimate the effects of a Lane-keeping Assistance System on accident avoidance and those of a Forward Collision Damage Mitigation Braking Control System on occupant injury reduction using 18 cases of single-vehicle accidents in Hiroshima Prefecture that occurred in 2017. In approximately 80% of these cases the accident was caused by lane departures and occurred during the day. It is thus likely a Lane-keeping Assistance System would have prevented these accidents. The author derived approximate expressions from the relationship between the collision velocity and occupant injury in single vehicle accidents stored in the database of the Institute for Traffic Accident and Research and Data Analysis (ITARDA). These approximate expressions are applied to the targeted case, to estimate occupant injury reduction by the Forward Collision Damage Mitigation Braking Control System.

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During automated driving categorized to the level 2 using Adaptive Cruise Control and Lane Keeping Assistance Systems, we analyzed the driving behaviors of 39 test subjects when presenting the system safety level and driving preparation level of drivers on HUD fixed on instrument panel. This driving behavior was classified, based on the gaze action and brake/gas pedal operation behavior of drivers, in a driving simulator investigation. As one of the experimental results, when system safety level and driving preparation level were presented to drivers simultaneously, the driving behaviors for risk avoidance was improved compared with a condition when the information was not presented to drivers. When presented with these two pieces of information, the driver was able to understand the task demands from the environment and showed appropriate driving behavior to keep the total driving performance of driver and automated driving system higher than the task demands.

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In introductory stage of automated vehicle into market, automated vehicle control reflecting individual driving style is presumed to contribute to secure feeling and acceptability. In this study, we proposed and demonstrated a modeling method with a small number of parameters to adapt brake timing at intersection by automated vehicle control to each individual characteristics. An experiment using a real vehicle on a proving ground showed the effectiveness of our method to increase the drivers’ secure feeling and acceptability.

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This study focuses on information contents to assist drivers in a transition from automated driving to manual driving in a non–emergency situation. In this study, the transition consisted of the combination of LKA (Lane Keeping Assist) and ACC (Adaptive Cruise Control) function with the time difference between them. In the experiments using a motion-based driving simulator, various information contents were designed and characterized based on the time period between LKA and ACC function deactivation. It is discussed how the contents influence on the driving performance and visual behavior in manual driving just after deactivating ACC function.

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To inhibit temperature rise of vehicle parts in the engine room, some vehicle models have been adopting After-cooling Control to operate the cooling fan for several minutes after engine key-off. In order to confirm the effect of After-cooling Control before the prototype car is made, a CFD method is required to predict the maximum temperatures of vehicle parts accurately. However, by After-cooling Control, the behavior of temperature becomes very complicated. To predict the maximum temperatures under the after-cooling condition, a high-speed computation method was developed. In this paper, the computational process and the prediction accuracy of maximum temperature are described.

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As a tool to evaluate the environmental performance in the real world, we constructed a NOx sensor-based emissions measurement system (SEMS) that does not require an installation location and is easy to install. We mounted the SEMS on a heavy-duty vehicle, and carried out two months of normal transportation driving, and long-term continuous data collection was conducted. As an example of environmental performance evaluation, from the relationship between vehicle speed, exhaust gas temperature and NOx emission rate, the functional state of the urea SCR system was estimated by visually representing the relationship between the driving state and NOx emission.

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In this paper, we report the simulation result of a hybrid navigation system using landmarks and lane detection to overcome weakness of GNSS. The positioning technology of a vehicle is one of the important elements to realize the autonomous driving. GNSS is often used for vehicle positioning, but the problem is that accuracy is reduced in urban areas and tunnels. To solve this problem, we developed a system that can estimate the position using a high definition map and LiDAR, radar, camera sensor instead of GNSS, and confirmed its performance by simulation.

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In this work, we propose a method for precise ego-motion measurement by camera (a.k.a. Visual Odometry : VO) even in high vehicle speed. The results of conventional VO methods suffer when using data points far away from the vehicle tracked by conventional camera, which have lower accuracy, but tracking objects and road surface close to the vehicle during high ego-speed is also difficult. We propose a precise method for ego-motion measurement using optical flow from a high-speed camera outputting 300 frames per second. The implemented method was evaluated on public roads.

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This paper proposes a parallel implementation technique using multi-core CPUs. We focus on model predictive control that’s an important part of the path planning for autonomous driving. From the results of analyzing the C/GMRES’s computational bottleneck, it was found that Gram-Schmitt process is the most time-consuming task. Hence, we propose a multi-thread technique to execute the Gram-Schmitt process with less computing time. In particular, we design a switching method to keep the calculation efficiency for small tasks. It’s demonstrated that the calculation speed was increased to 1.46 times by the proposed method when it was implemented to a typical device.

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The wireless communication is the key technology for the implementation of the next-generation transportation infrastructure. In other words, V2X (Vehicle‒to‒Everything) will become the common approach of a local communication around a moving vehicle, which introduces a safe, reliable, and efficient communication framework to traffic infrastructure. However, the introduction is almost at a standstill because the current vehicle does not have appropriate and sufficient wireless communication to realize the V2X. We propose a low‒latency, high‒reliable and widely‒available wireless communication based on IEEE 802.11p, which is realized on an FPGA (Field Programmable Gate Array) and the systems were evaluated on two moving electric vehicles. Besides, this paper discusses an image compression mimicked by human eyes because image-based data sharing must increase and the data volume will arise a problem.

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In the first report, the scientific nature of autoignition prediction using the Livengood-Wu integral was investigated. X of the Livengood-Wu integral is no more than the ratio of an integration step out of ignition delay time. Assumed that the profiles of heat release rate along the time normalized by ignition delay times are similar, when the integrated value reaches 1, the parts of a profile of heat release rate can be integrated to be the complete profile. In the second report, ignition delay time equations for a premium-gasoline surrogate fuel were developed, which can reproduce the temperature-, pressure-, and equivalence ratio-dependences of H₂O₂ loop induction time and ignition delay time produced using a detailed reaction mechanism, with high accuracies in a wide range of temperature and pressure. In the present report, the Livengood-Wu integral using these equations has been investigated. Unfortunately, this approach cannot be effective for all possible in-cylinder autoignitions. Prediction errors are significant for HCCI’s after TDC and end-gas autoignitions. Error factors in the Livengood-Wu integral using the high-accuracy ignition delay time equations have been investigated. Errors are accumulated during the H₂O₂ loop induction part of ignition process, which is contrary to the general impression that the primary error cause is the H₂O₂ loop dominant part.

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Abnormal combustion phenomena especially referred as low speed pre-ignition (LSPI) is so destructive that the torque and fuel economy of turbo charged direct injection gasoline engine are restricted. Recent technical papers report that the additives in engine oil are related to the occurrence of LSPI events. In order to verify the results of reports and seek for a kind of oil which is capable for running at IMEP 2.4MPa without LSPI, 8 kinds of oil blended with the combination of 3 additives (Ca, Mg, Mo) were tested on a 2.0L turbo charged direct injection engine. Different to other previous researches, the test conditions were set at various kinds of engine load, engine speed and EGR ratio, in particular, up to IMEP 2.4MPa was conducted for the evaluations. Thereby, the influences of engine load, engine speed and EGR ratio were also evaluated.

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In the future, there is a movement to reduce the number of diesel vehicles, and it is expected that diesel fuel might be in excess. The purpose of this study is to propose a fuel design by mixing the surplus diesel fuel into gasoline and apply it to gasoline engines. In this report, it was evaluated the macroscopic and atomization characteristics of spray by changing the fuel composition and investigated the effect on wall impingement. As a result, gasoline spray mixed with diesel fuel component made lager droplet, therefore fuel droplet impingement behavior might be difference.

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The ignition device with dielectric barrier discharge (DBD) may realize volumetric ignition without electrode erosion. A DBD ignition device has been manufactured for achieving the volumetric ignition. The characteristics of DBD ignition under elevated pressure condition in a constant volume combustion chamber was evaluated experimentally. Results show that DBD enables volumetric ignition at more than a certain pressure, and the threshold pressure increases as the excess air ratio increases. Furthermore, the images taken by high-speed camera suggested that reducing the electrode heat loss can improve lean limit of DBD ignition.

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In order to enhance the passenger protection performance in frontal collisions for passenger cars in real world accidents, the car-to- MPDB(Mobile Progressive Deformable Barrier) frontal impact test will be started in EuroNCAP in 2020. In this study, car-to-car crash test was conducted to confirm the validity of the MPDB test method. As a result, we found that there is need to review in the compatibility evaluation method of the MPDB test.

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The retrofitted advisory systems (RAS) equipped in vehicles is considered as an effective measure to ensure driving safety for elderly drivers. In this study, a field experiment was conducted to investigate the impact of alerts of the RAS on the driving behavior of elderly drivers. Using probe data collected from 12 elderly drivers, we analyzed the driving behavior of them without alters and that with alters. The significant findings indicate that 1) driving behavior of elderly drivers changed obviously by the alerts; 2) 75% of participants reduced the number of rapid decelerations (>= 0.3G) at the end of the experiment.

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At Levels Two and Three automated driving systems, it is important to develop an environment to keep driver's awakening level. Visual stimulus is one of the solutions but it may cause distraction to driver. In this study, we examined our proposed visual stimuli on 10 subjects. Each of them drove on a driving simulator and vehicle while being stimulated with our visual stimuli. We then took their awakening and distraction level. Subjective evaluation shows the potential of keeping driver's awakening level with less annoying. This paper describes the details of the shape of stimuli, experiment and results.

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In order to achieve a quiet cabin, reducing wind noise level is important. Especially, underbody wind noise mainly contributes to interior noise in mid frequencies. Aero–vibro–acoustic coupling simulations have been performed to research the mechanism of automobile underbody wind noise. The external flow and acoustical fields were simulated by Computational Fluid Dynamics. And the vehicle structure vibrations and the interior sound fields were analyzed by Finite Element Method. As a result, the mass law pass is dominant above 200 Hz. In addition, it is concluded that an engine under cover is useful to reduce interior noise level.

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