Direct-injection spark-ignition (DISI) engines have high thermal efficiency; however, they also show high soot emissions under cold-start conditions. It is also well-known that fuel-injection timing has a significant effect upon soot emissions, and that such emissions increase when fuel is injected during the early intake and latter compression strokes. In design calculations, it is important to reproduce this characteristic profile of soot emissions, what we call the bathtub-type profile. In this study, we performed numerical calculations of soot emissions from a DISI engine under cold-start conditions by using a compact-size soot-formation model previously proposed by authors. As results, it was shown that the proposed model reproduces the bathtub-type profile well. Furthermore, by changing the model of the HACA mechanism and adjusting the model coefficient, the quantitative reproducibility of soot emission was improved while maintaining the bathtub-type profile.

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Ammonia slip catalyst (ASC) prevents the emission of ammonia to the atmosphere by oxidative decomposition of excess ammonia in the urea SCR system. In a series of studies aiming at the development of the plant model of ASC, we tried the method of making a mixed catalyst model from two types of catalyst models of SCR and PGM which constitutes ASC. The mixed catalyst model with NH3 adsorption sites on Cu-SCR and PGM was able to accurately simulate NH3 oxidation activity. We discussed the technical points of the new method of making a mixed catalyst model and applicable objects.

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We tried modeling of ammonia slip catalyst (ASC) for the purpose of model-based development of urea SCR system which is NOx purification device for diesel exhaust gas. In this report, the practical one-dimensional dual-layer ASC model is developed. This model is made by adding a correction factor to gas adsorption reaction parameters of the previously reported mixed catalyst model. As a result, this model can predict product selectivity of dual-layer ASC in different SCR and PGM washcoat loadings. This model is more practical than previous ASC model and is expected to contribute to efficiency of model-based development.

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In order to estimate the hydrothermal aging of SCR catalysts for heavy-duty vehicles used in real driving conditions, we quantified SCR hydrothermal aging of user vehicles by using connected data and a previously reported hydrothermal aging simulation model. In addition, we collected SCR catalysts from four user vehicles, and evaluated their NOx purification performance. From these evaluations, it was estimated that the hydrothermal aging degree of SCR catalysts installed in the user vehicles were much lower than that of the reference sample for aging.

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In order to clarify the in-cylinder wall heat loss phenomena, visualization of flame behavior and wall surface temperature distribution was attempted in a top-view optical engine. Infrared radiation from chromium coated quartz window surface was visualized by high-speed infrared camera. Heat flux sensor measurement and CFD simulation were also conducted to compared with infrared radiation and to consider the effect of wall material difference between quartz and metal. Furthermore, appropriate sensor layout was investigated from distributions of infrared radiation taken by high-speed infrared camera. The obtained high-speed infrared images successfully demonstrated the potential of the visualization technique for qualitative measurement of wall surface temperature distribution, which will be beneficial for fundamental understanding, model development and its validation of the wall heat transfer process. As for the sensor layout consideration based on high-speed infrared images, it was found that wall heat loss within φ30mm can be obtained by radially dividing the measurement area into three and using nine sensors.

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Although it is reported that ash is generated from combustion of a lubricant oil, there are few studies on the kinetic mechanism of the ash under the combustion conditions. In this study, the reaction pathway for ash formed from the oxidation of Ca-based lubricant oil additives in a flow reactor was investigated. The quantitative analysis of the ash components formed from the oxidation of calcium sulfonate and calcium salicylate in the temperature range 773 – 1373 K was performed through high-performance liquid chromatography. It is found that the ash components were mainly oxides of typical metal components contained in lubricant oil additives. Based on the analysis of the temperature-dependent products, reaction mechanism for ash formation was evaluated.

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A catalytic activity in an electric field was researched for further lower cost and more compact exhaust gas control system of plug-in hybrid electric vehicle than electrically heated catalyst system. Firstly, an experimental equipment and test protocol for an electric field was constructed. Secondly, it was confirmed that the catalytic activity in an electric field with palladium-ceria-zirconia complex oxide catalyst was occurred in the low temperature range where the conventional catalytic reaction was inactive. Finally, it was found that the catalytic activity in an electric field could be optimized by the catalyst specifications and the electric current.

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The particulate matter (PM) emitted from the diesel engine is collected and removed by the diesel particulate filter (DPF). When performing PM removal, it is necessary to raise the temperature of exhaust gas, so deterioration of fuel efficiency is a serious problem. Therefore, we aim to propose an optimal DPF structure with catalyst addition. In this study, PM combustion behavior inside the DPF when the catalyst is supported is carried out by numerical calculation. As a result, the effectiveness of the catalyst is recognized. It is found that there is a difference in the amount of PM combustion change according to the difference in the activation energy. In this result, it can be suggested that a catalyst having activation energy ΔE = 120 KJ/mol or less is effective. It is also possible to completely remove PM in a single regeneration by using a catalyst with low activation energy or by increasing the exhaust gas temperature. The calculation technique we proposed will enable the qualitative examination of the structure of DPF with catalyst addition, which can be useful for the optimization design of DPF.

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The deep learning model we developed estimates knocking sound pressure and knocking component superimposed on in-cylinder pressure from engine radiation noise measured by a microphone. This model obtains the time frequency mask and frequency response from many pair data of engine radiation noise and in-cylinder pressure. The time frequency mask extracts the knocking sound from engine radiation noise. The frequency response converts the extracted knocking sound into the knocking component superimposed on in-cylinder pressure. We propose an improved model to separate the knocking sound from the engine radiated sound in order to evaluate the magnitude of the knocking sound.

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Controlling the knocking is essential for achieving high compression ratio and high thermal efficiency of internal combustion engines. Previous studies have shown that NO/NO2 present in EGR affects autoignition. However, the mechanism has not been fully understood. In this study, kinetics and role of elementary reactions of NO and NO2 and fuel-derived intermediate products were investigated.

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The accurate prediction for damping performance is required in early stage of development because damping device such as flywheel, is strictly restricted in space of engine room. However, the accuracy of estimation of engine torque fluctuation is low and this causes redesign the concept of vehicle. In order to solve this problem, we constructed technology using statistical method that enable to predict high accuracy within 5 % of engine torque fluctuation without having actual engine. This paper introduces this new method.

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In the first report, a method of estimating the vehicle body slip angle by trigonometric algebraic calculation was proposed. Two estimation methods are proposed using the basic formula. One is a method that combines the basic equation and the random walk model. The other is a method that combines the basic equation and the equation of motion of a rigid body. Both methods are realized using the extended Kalman filter. As a result of research, it was found that both methods can accurately estimate the vehicle body slip angle. However, it was confirmed that the estimation accuracy deteriorates due to the offset of the acceleration sensor signal. To solve the problem, we also propose a method using a linear observer.

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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. In the research of the previous report, the quantitative relationship of several steering characteristics in this scenario was clarified for accurate line tracing. However, it was found that the deviation of the tracing line by trials was not small at the same time. This paper clarifies one of the factors of the deviation and its improvement by adding minute pitching motion to the vehicle in proportion to the steering angle.

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Longitudinal vibration suppression control using experimentally identified driving system model is effective for improving ride comfort. Previous studies do not consider velocity dependence of tire force. But the actual driving system has velocity dependence and it leads to control performance deterioration. In this paper, this characteristic is taken into consideration by using proposed model. The effectivity of the proposed model is verified with experimental results.

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It has long been considered that there is a limit to the eigenvalue analysis used to discuss the straight running stability of motorcycles. The energy flow method was proposed to solve this problem. However, it is found that the calculation method used in the energy flow method and the eigenvector equation are exactly the same. Based on this fact, a new formulation method is proposed that allows detailed discussion of straight running stability using only the eigenvector equations. This means that the traditionally used eigenvalue analysis contained useful and detailed information, but for a long time it was only unknown how to use that information.

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Drivability is one of vehicle’s core performances. The standard evaluation method considers constant pedal operation, but the actual customer behavior is more complex based on his Cognition, Planning and Action. This paper reports a new evaluation process using a driver model which accounts for the customer’s actual operation.

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This study estimated the benefit of Automatic Emergency Braking [AEB] in vehicle to pedestrian collisions in various situations where pedestrians crossed the road in front of a vehicle. A series of 17,000 cases were simulated for both with and without AEB. The collision avoidance effect was estimated from the reduction in number of collisions. The injury mitigation effect was estimated from the reduction in fatal injury risk calculated using the human body FE model. The simulation results indicated that AEB reduced the number of collisions by 84% and lowered the fatal injury risk by 75%.

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The purpose of this study is to investigate the evaluation method of brain injury due to whole-body kinematics of a child in car impacts. A fullscale impact experiment was performed using a six-year-old child dummy to measure the trajectory and the brain injury metric. In addition, an impact simulation using a human FE model was performed in the same condition. The trajectory and the time history of the brain injury metric were compared between the experiment and the simulation, showing that the child dummy reproduced the characteristics of those from the experiment.

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In this study, a simplified model which allowing easier design parameters of body deformation, restraint system and occupant package was developed to conduct feasibility study if planed vehicle satisfy occupant injury values of side collision in the early stages of planning phase. And the injury value database was constructed by side collision CAE analysis results calculated from the simplified parametric model, included of compact car, sedan, and middle size SUV. Based on this database, correlation maps were created between the design parameters and the injury values that enables highly responsive injury value predictions.

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In this study, in order to investigate the protocol which evaluates false reaction of Advanced Emergency Braking System for passenger vehicles, the plural scenarios were developed by referring to such kind of information in the owner's manual of car manufacturers, etc.. And next, the experimental vehicle tests which validate the scenarios were carried out. And then, the other experimental tests were carried out in order to research driving behavior of normal drivers in the traffic scene of the scenarios, and the experimental results were reflected to the scenarios.

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Slipping of the lap belt from the anterior superior iliac spine (ASIS) during frontal impacts is an important issue because it can cause injuries to the abdomen. In this study, the abdominal and the femur shape of the occupants and position of the lap belt, seat pan angle, lap belt pretensioner and the position of the ASIS w.r.t the lap belt were examined to investigate the occurrence of submarine. The human model with a flat abdomen and thick thighs, can lead to submarining depending on the belt anchor position, seat pan shape and lap belt pretensioner.

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The working brake lights are only the way to recognize the deceleration of preceding vehicle even if the vehicle is equipped with a highly developed autonomous driving system. The prior recognition of deceleration intent would cause a mitigation of a risk of rear-end collision especially in a high-density and high-speed car-following state. The authors have been developing a system that infers deceleration intention 1.5 s in advance of its driver’s most likely action. However, the previous system that utilizes an unscented Kalman filter (UKF) consists of two isolated processes, a state estimation of vehicle platooning and a prediction of deceleration intention. This separation causes an over- or under-estimate of the intent to worsen the prediction precision. This paper aims to improve the intent inference system by combining both processes within a single procedure. In addition, artificial neural network model and multiple regression model are introduced to estimate both vehicle state variables together with the inferred intention. Numerical analyses showed that the revised model provided more accurate intention compared to the previous system for all five participants. It can be concluded that the integrated state feedback system is appropriately working not only for the state estimation but also the prediction of deceleration intent inference.

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In order to detect abnormal physical condition during driving early, we focused on the visual function that is important for safe driving, worked on detection of homonymous hemianopia which is one of the symptoms of stroke. We have built a method for anomaly detection from driving characteristics changing by homonymous hemianopia, and evaluated the robustness of this method in the actual road traffic environment.

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It is important to elucidate what the drivers perceive to operate the vehicle in order to apply the driver characteristics to self-driving cars. Therefore, we proposed the driver's cognitive-operation model using deep learning. Then, we used the proposed model to analyze the cognitive areas of drivers that influence the speed control of the vehicle. We verified whether the results obtained in our study are consistent with the driver behavior that is proven by the prior studies. As a result, we showed the reliability of the proposed driver's cognitive-operation model that can extract the driver behavior.

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This study investigated driver’s face images on public roads using a commercial driver monitoring system, aiming to make feedbacks about how the drivers check the safety. The study focused on the head movements of older drivers versus middle-aged drivers, and high-speed drivers versus low-speed drivers, observed at stop-sign intersections. It tested several measures that characterize the temporal and spatial aspects of head movements. Two sample t-tests revealed the significant decrease in head speed, head angle, and the increase of the ratio of short duration in the high-risk driver groups, suggesting the usefulness of head movements for driving assist systems.

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Understanding characteristics of drivers is important for realizing autonomous driving in urban areas that are accepted by passengers and surroundings. Avoiding parked vehicles is a difficult urban driving situation because of multiple risks such as oncoming and parallel vehicles and pedestrians jumping out of a blind spot. In this study, we formulated a hypothesis of the driver's judgment process and driving behavior during parked vehicle avoidance with oncoming vehicles and clarified characteristics of driver’s judgement about whether to go first or wait and of the executed path and speed profile in an experiment on a test course.

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Passenger's body behaviors and subjective evaluations of comfort were measured for four types of braking patterns. The result of multiple regression analysis on subjective evaluation values and body behavior showed that shoulder angle contributes to the evaluation of comfort. Furthermore, the result of comparing the relationship between the comfort score and body behavior based on each participant’s highest braking pattern comfort score suggested that the difference in the comfort evaluation may be affected by the difference in the timing of holding the body against the braking G-force.

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Applying the MBD method to engine control development is improving model accuracy. Model-based control using the improved model is expected. In this research, we will explain Model-based A/F control design utilizing transient flow meter. In addition, we describe parameter adjustment time reduction by the extended kalman filter.

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Ventilation seat is equipped for both saving energy of the air-conditioning system and thermal comfort of the passenger. The improvement effect of the ventilation seat on the thermal comfort needs to be evaluated quantitatively in order to find the better operating condition. In the present study, the human-subjective experiment has been performed and the amount of the sensible and latent heat transfer has been identified. The results showed the amount of the latent heat transfer was two-times larger than the sensible heat transfer when the human subject had the thermal sweating. After a lapse of 20 minutes from the ventilation seat strongly ON, the thermal sensation vote achieved thermal-neutral state.

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The diesel particulate filter (DPF) that collects PM in diesel exhaust requires a regeneration process that burns and removes PM to prevent clogging. At this process, since the DPF is brought to a high temperature state by the fuel increase, there is concern about deterioration of fuel consumption and thermal degradation of the rear-stage SCR catalyst. In this study, we investigated the regeneration frequency during actual road driving, the behavior of exhaust gas during regeneration, and the fuel increase. Furthermore, to study the thermal degradation of the SCR catalyst, the amount of heat added to the catalyst was estimated.

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When vehicles are pooled in a coastal area, specific disfiguring rust may be generated on exhaust parts made of stainless steel. This study is to build the simulation technique and to clarify the mechanism. This result indicates that the corrosion morphology forms by exhaust heat and magnesium chloride (MgCl2). Furthermore, we conducted seasonal outdoor exposure tests to investigate the main environmental corrosion factors and the corrosion transition behavior of each stainless steel, and built a corrosion prediction method.

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Low frequency vibration cutting which is effective for chip breaking, chip ejection, and physical load reduction of tool is manufactured characteristic surface textures resulting from synchronization of spindle rotation and feed motion vibration. We report a new measurement and evaluation method using the characteristic surface texture by low frequency vibration cutting and evaluation results.

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In automated driving, traffic light information is essential to determine whether to pass through an intersection. No matter how accurately automated vehicles can recognize traffic lights, when the signal suddenly turns yellow while approaching an intersection, the vehicle will need to decelerate suddenly to stop. In this study, road-to-vehicle communication provides automated vehicles with the signal state and the time to change the state, and aims to reduce the rapid deceleration. Then, it was found that the deceleration could be reduced from more than about -3.0[m/s²] to less than about -1.5[m/s²] through simulation and verification in the real environment.

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For map generation, road environments need to be precisely measured on the basis of information from sensors mounted on cars.We introduce an effective statistical method for more accurately estimating road signs' locations. We improve the accuracy of location estimation by selecting preferable estimation results among the results obtained by conventional triangulation based method utilizing even low cost GPS locator and images obtained from in-vehicle monocular camera.

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A new convective heat transfer model is was developed for the 1D CFD on gasoline engine MBD. At first, 3D CFD with modified wall function and non iso-thermal heat transfer model was verified and applied for the analysis of the in-cylinder combustion and heat transfer phenomena, and for the modeling of heat transfer. It was observed that the heat transfer is mainly affected by the burned gas velocity derived from the fluid expansion of combustion. Therefore, the new model is based the burning velocity. Heat transfer rates of the new model were well agreed with those of 3D CFD and the error of fuel consumption prediction was reduced to almost 1/3.

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To correspond with CO₂ reduction from the automotive, in conjunction with electrification, improving the thermal efficiency of ICE are crucial and lean boosted SI engine is being studied. However, the combustion limitation is one of the issues for this technology, therefore it is important to clarify the spark ignition mechanism. In this study the in-cylinder condition which dominate the spark-ignition duration is examined and the effect of turbulence is revealed.

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To correspond with CO₂ reduction from the automobile, in conjunction with electrification, improving the thermal efficiency of ICE are crucial and lean boosted SI engine is being studied. However, the combustion limitation is one of the issues for this technology, therefore it is important to clarify the spark ignition mechanism. In this study the discharge path length history is analyzed to reveal the influence on ignition duration.

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HCCI combustion model has been constructed for development of switching strategy from SI to HCCI. An engine test indicated the differences of heat release between steady and transient on HCCI operation. It analyzed with CFD and chemical kinetics calculation that the change of heat release derives from the wall heat transfer. In-cylinder space is divided into three zones so that the combustion end timing might be characterized from a state transition in a low temperature region near the chamber wall.

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Dynamic wireless power transfer technology is studied to enhance cruising distance of electrical vehicles. The authors have developed transmission coils which can transfer high power of 20 kW and whose size is small compared with the previous coils. This paper describes the analytical results how the installation rate of the transmission coils can be reduced by the developed coils based on the data of the transmission efficiency and real drive data.

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In the improvement of vehicle dynamic performance, an essential understanding of vehicle characteristics is required. A single simulation can only give results under a single condition. If we want to know the state of a point that is slightly off from that condition, we must repeat trial and error. Such an approach is not enough to know the nature of the whole vehicle performance. The “Contour method” is developed as a method to see through the entire vehicle dynamic characteristics. According to this method, it is possible to understand the steady-state characteristics and transient characteristics with simple operations regardless of the linear and nonlinear regions. In this paper, we describe the theory underlying this method.

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Personal Mobility Vehicle (PMV) which has an inward tilting angle according to the steering angle, turns with the lateral force due to large camber angle, so it is necessary to consider the lateral movement of the tire vertical load axis during turning. Although the steering torque mechanism are very different from those of automobiles, there are not many examples which studied the steering torque mechanism of PMV. In this study, based on the effects of six components force acting on the tires, a method for setting the steering axis specifications is derived, including the geometrical minimization of steering moment disturbance due to the vertical load reaction force during turning.

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In this study, based on the concept of a structural hierarchy that classifies structures into main primary and secondary structures, topology optimization calculations with a load transfer index Ustar (U* value) were performed for a passenger car door structure. Considering the four conditions of load transfer path theory, the objective function was defined and optimized. The primary structure of the main load transfer path was emerged. For supporting the primary structure, secondary structures were randomly arranged and optimized for improving uniformity and continuity of load transfer on the primary structure. The obtained results showed that the load transfer of the door panel was greatly improved. Considering the door panels as one of the car body structure, i.e. load transfer members, the optimized door panels contribute to enhance the specific stiffness of the car body structure.

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We present a modeling method for self switchable hydromount from the specification of spring and damping by using machine learning. This is because this component has a non-linear characteristic depending on amplitude and frequency, so it is difficult to substitute to the equivalent dynamics system which is generally performed in the time series calculations at the model-based development. We confirmed the model’s prediction accuracy and also inspected the calculation stability when it is incorporated in 1D-CAE.

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Pedestrians and cyclists account for a large proportion of traffic accidents in Japan. In this report, we investigate the driving behavior of general drivers when they pass by pedestrians using a driving simulator. Some factors influencing driving behavior included attributes such as road width and pedestrians, as well as the presence or absence of oncoming traffic and distance from one's vehicle. The results show that the two driver types can be categorized into drivers who perform safe driving behaviors when crossing pedestrians and drivers who are slightly less safe, and these two driver types have very different driving behaviors.

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The chest of occupants is frequently injured in car crashes. In this research, the chest deflection in a seat belt loading was compared in THUMS, Hybrid III and THOR. There are three modes of rib deformation in THUMS resulted from different load of the seat belt. The first mode of rib deformation is caused by a load applied to the costal cartilage, the mode pattern is caused by load applied to the front edge of rib and the third was S-shaped deformation caused by load applied to the side of rib. Though the S-shaped rib deformation was observed in THOR, the chest deflection of the THOR did not represent rib fracture risks because the measurement points are located at the anterior edge of the rib.

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Recently, research and development of autonomous driving technology has been actively conducted. In order to autonomous driving technology to be widely accepted by general users, sensory of security and comfortable behavior of vehicle is required. Therefore, this study aims to clarify the relationship between sensibility of occupant and brake operation during autonomous driving. Questionnaire surveys using real vehicle were conducted. From the result of using the average value, we could not show the feature about the brake operation. However, by classifying into groups using cluster analysis, the details of braking preference of each type were clarified.

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The aim of this study is to collect basic data for the prevention of accidents caused by pedal misapplication among the elderly. We hypothesized that frequent pedal changes in parking lots would increase the variance of the foot position on the brake pedal. We install on-dash cams in cars owned by elderly drivers and asked them to drive freely. The results supported the hypothesis. It is possible that this large variance may be a cause of the pedal misapplication.

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Headlamps are usually not activated on fuel economy tests in type approval. However, headlamp usage would affect the fuel economy due to the increase of energy consumption and the ineffectiveness of lead-acid battery charging control in conventional internal combustion engine (ICE) vehicles. In this paper, the influence of headlamp usage on the actual fuel economy was investigated by driving cycle tests on a chassis dynamometer using an ICE vehicle and a survey for headlamp use frequency based on vehicle data in the Japanese market. As a result, the actual fuel economy was estimated to reduce by about 1.2% - 2.0% due to the effects of headlamp usage.

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This study demonstrates a local peening method using a tool with small tip radius. Frist, the effect of material strength on the improvement by the method was investigated, which showed the fatigue strength of the peened joint was improved to the level of the base metal with tensile strength grades of 440 MPa and 980 MPa. Second, the effect of the peening pattern was investigated, which showed the width of the peening pattern affected the crack initiation site. Finally, the technique improved the fatigue life of a closed-section lower suspension control arm more than three times by enhancing the fatigue strength of the weld toe.

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Rework of system development needs to be reduced to meet planned quality, cost, and delivery. This white paper introduces a safety analysis focusing on the interaction with the products related to the development target product in order to reduce the rework in the functional safety development of in-vehicle electric and electronic systems. As an example, we apply HAZOP safety analysis to a system model that describes an electronic parking brake system. In this case, we show that we can find more malfunction modes of the development target product by using not only the structural model but also the behavior model.

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