In a gasoline exhaust aftertreatment system, a three-way catalytic converter (TWC) is used for the reduction of CO, HC, NOx. Recently, for the reduction of particulate matters (PMs) including soot, a gasoline particulate filter (GPF) is also needed. The coated GPF, called a four-way catalytic converter (FWC), has been developing. However, the performance of the catalyst may be dropped by the deposited soot. In this study, we simulated a CO catalytic reaction in the GPF with soot deposition layer. Effects of substrate temperature, inflow velocity, and the amount of deposited soot were investigated. Results show that, when there is soot layer on the filter wall, the distribution of the velocity across the filter wall changes. When the substrate temperature is higher or the inflow velocity is smaller, the conversion ratio of CO to CO₂ increases. The soot layer changes the velocity across the filter, which affects the CO conversion ratio.

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Efficient development of powertrain is expected. In order to achieve high efficiency development, concurrent development is required by cooperation among subsystems. In this study, we have developed a real-time engine modeling technology that enables accurate prediction, short modeling time and real-time computation to realize the concurrent engineering.

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In order to investigate effects of wall surface roughness on heat transfer on the wall impinged by diesel spray flame, chromium-coated quartz windows with optical polished and roughened surfaces were prepared and infrared thermography of the back surface of the coating was conducted using a high-speed infrared camera. The experimental results showed that both surface cases exhibit radially striped waving patterns of radiation intensity. However, roughened surface case exhibited more vaguely delineated and quickly dissipating distributions of temperature, heat flux and radiation pattern moving velocity compared to the optical polish case.

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Toyota has created a new development methodology by utilizing model based technology for front loading purposes. In this paper, we report the methodology and the thoughts of efficient calibration process for On Board Diagnosis (OBD) by constructing a powertrain system coupled model during the system planning stage.

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A novel heat release rate profile named ‘High heels’, which is formed by gradually increased heat release rate in two steps to retard the peak at the timing of higher volume-change rate, was proposed as a measure to practically maximize thermal efficiency of diesel combustion in lieu of the ideal thermodynamic cycles. In this study, a newly developed variable injection rate shaping system for a single injector was installed in the tested engine. The results indicated that significant reduction in cooling loss and increase in thermal efficiency were simultaneously achieved with ‘High heels’ like heat release rate profile, as expected.

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Oil film thickness on a side surface of a lower rail of an oil ring was measured to clarify the mechanism of engine oil consumption. Two optical fibers were embedded in the lower side surface of the oil ring groove, and oil film thickness was measured by laser induced fluorescence method. It was found that the waveforms of the oil film thickness showed some patterns. Those waveforms were compared with inertial force, pressure at around the oil ring and so on, and the reason of the waveform of each cycle was discussed.

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In the early stage of vehicle planning phase, multifunctional trade-off studies about layout of frame structures are required. Computer Aided Engineering (CAE) / Machine Learning (ML) technique is proposed to conduct multifunctional trade-off study between mass and performances. ML models were created from the database that was constructed from large number of parametric FE analysis. Performance maps that were drawn based on ML result enables visualization of trade-off relations.

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To reduce road noise effectively, focusing on high contributing principal component (PC) modes is a well known method. Although, the difficulty of simultaneous measurement when applied to actual vehicle test is one of the issues. Therefore, a method was proposed to obtain the whole body PC modes by integrating the partial PC modes. In this paper we applied this method to an operational test data for each measurement group and obtained the whole body PC modes, the effectiveness of the proposed method for practical usage was proved.

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The operating feeling of rotary switches used in various in-vehicle equipment influences our impression of the vehicle itself. Thus, the operating feeling needs designing appropriately by understanding the correspondence with the relevant physical characteristics. This study evaluated the onomatopoeic free-answer and the semantic differential method using adjectives for operating feeling of rotary switches, which consists of tactile and auditory stimuli. Two experimental results showed the relationship between phonological characteristics of onomatopoeia, adjectival expressions, and physical characteristics of stimuli, respectively. Moreover, we indicated the features of onomatopoeic and adjectival expressions in the design of the operating feeling consisting of multimodal stimuli.

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The part b-factor analysis as a method to quantitatively evaluate the deformation form of parts in the natural vibration mode of a structure using the first-order sensitivity of thickness and Young's modulus to the eigenvalues obtained from modal analysis is proposed. This analysis is applied to the vehicle body to confirm that the bending deformability of each part, “part b-factors”, have values in the theoretically predicted range of 1 to 3 for several natural vibration modes of vehicle body. Then, parts that require structural improvements to improve eigenvalues while reducing the increase in the mass of vehicle body are selected based on sensitivities and part b-factors, and their effects are verified. In addition, by comparing the part b-factors in several natural vibration modes, the relationship between the deformation modes of the entire vehicle body and the deformation modes of individual parts is discussed.

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In order to efficiently develop innovative multifunctional materials, we are developing a multifunctional simultaneous control model technology based on the concept of Model Based Research (MBR). So far, control model technologies for sound absorption and heat insulation functions have been developed. In this study, we have developed a microscopic structural design model technology for porous materials that controls the vibration isolation function. In the future, we plan to combine this technology with the previously developed models to construct a simultaneous control model for sound absorption, heat insulation, and vibration isolation functions to realize innovative material development.

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We establish procedure to predict stress distribution by machine learning focusing on the plastic deformation of bending plate in press forming. Since the press forming is nonlinear elasto-plastic behavior, implicit or explicit methods generally use incremental analysis. On the other hand, many data are indispensable for building the machine learning model. Therefore, we adopt the one-step method, which can significantly reduce the calculation cost of the finite element analysis. We validate prediction of stress distribution due to plastic deformation in the plate by machine learning by comparing the finite element analysis results.

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To estimate the on-road emissions of the light-duty vehicles, Real Driving Emission (RDE) testing method is adopted. At Japanese RDE test, it is possible to drive the test vehicle at test course. When we drive the test vehicle at test course, we have to follow the reference vehicle velocity pattern as well as Chassis dynamometer test. But it is difficult to measure the correct emissions data and to safe at the driving test. In this study, to obtain more correct RDE data, we adopted the driving robot, which is consist of the compact size and the simple simulation logic of the driving operation. By using this driving robot, it was possible to keep the equity, efficiency and safety at RDE test.

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Quantitative estimation methods of hydrogen and oxygen concentrations in gasoline engine exhaust gas are studied. About hydrogen, oxygen each, two kinds of method are evaluated. One is a method to recur from the correlation with the measurable gas components in FTIR analysis and the other is one using the infrared absorption spectrum. These are compared and validated in gasoline engine out exhaust gas emissions both in steady-state and transient operations.

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The study discusses the catalyst loading position of diesel particulate filter (DPF) and the effect of catalyst loading on the pressure drop. A PM oxidation catalyst is used in the regeneration process to reduce the temperature of the regeneration process. The catalyst is made of expensive precious metals, etc. The amount of catalyst used needs to be reduced. In addition, the catalyst is coated on the surface of the DPF, which narrows the pores and increases the pressure drop. In this study, the numerical model of the previous study was improved, and the effects of catalyst loading position dependence and catalyst loading and exhaust gas temperature on pressure loss were numerically calculated. The results show the PM oxidation behavior depending on the catalyst loading position and the effect of catalyst loading on the pressure drop.

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NH₃ is a promising substitute for fossil fuels, but its low ignitability and low burning speed are major challenges, hence mixing with diesel oil is effective for applying internal combustion engines. In this study, effects of NH3 mixing ratio and air fuel ratio on combustion and emission characteristics have been investigated by numerical approach and experiment on NH₃-diesel dual fuel engine under high load condition. Emissions of NO+NO₂, NH₃ and N₂O are affected by air fuel ratio but it’s difficult to prevent them completely by only improvement of combustion. Therefore, aftertreatment system is mandatory for NH₃ internal combustion engine.

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Spark ignition engines have a fateful event that enhancing EGR rate makes cycle-by-cycle variations and then ends up its combustion limit. To unveil this event, spark discharge images were shot with a high-speed video camera, and spark discharge electric current and voltage, in-cylinder pressure were measured at the same time under high EGR rate combustion. The relations between spark discharge behaviors and combustion characteristics were investigated. It is discussed here how initial combustion speed variations, which caused by differences of spark discharge behavior among cycles, affects the combustion cycle-bycycle variations.

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This study proposes a new current control method for reduction in noise and vibration of a switched reluctance (SR) motor. We focus on the spatial radial force distribution of the SR motor. The motor current is regulated to make the DC component of the radial force distribution constant, resulting in reduction of a circular ring mode deformation. Based on the radial force distribution of the SR motor calculated by finite element method (FEM), the current reference waveform was determined to have the constant value of the circular ring mode deformation. The FEM structural analysis and vibration measurement test for a 12-slot/8-pole SR motor was performed. The results have shown that the proposed current regulation has the effect for reducing the vibration and noise of the SR motor.

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Magic Formula (MF) model has been widely used for vehicle dynamics simulation as a semi-empirical tire model, since it has a high fidelity to express the tire force and moment. However, MF parameters are required to be identified with the measured data. Accordingly, there are difficulties to use the model prior to the tire detailed design, prototyping and testing. This paper proposed Inverse Magic Formula (IMF) capable of defining the MF parameters virtually based on the typical tire performances inputs. Although MF consists of nonlinear functions, IMF was formulated analytically for ease. Therefore, virtual tire models can be generated artificially without prototyping. The proposed method is capable of tire requirement analysis by using vehicle dynamics simulation in combination.

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Various control methods and control devices have been developed to enhance vehicle stability, controllability and comfortability. However, it is difficult to design control systems that consider the coupling between planar and sprung motion. Therefore, we proposed an integrated vehicle dynamics control method in the previous paper. However, it cannot be applied to brakes that are equipped in all cars standardly because of the constraints that they generate only negative forces. In this study, we proposed a method that makes it easy to install integrated control with brakes by applying the Active-Set Method. The effectiveness of the method is verified using full-vehicle simulation and an actual car.

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A robust bump detection in the road surfaces is very important to ensure safe and smooth autonomous driving. However, it is very tricky to distinguish these features based on the distribution pattern of LiDAR 3D point clouds because of sparsity especially at the far distances. Therefore, we propose in this paper a time-series based method to precisely analyze the road profiles using the elevation maps.

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In this study, at first, the environmental conditions in which the Autonomous Emergency Braking Systems (AEBS) tends to occur false-positive actions is specified. Subsequently, the method which can evaluate the false-positive of AEBS quantitatively by using the logistic regression analysis is developed depends on experimental results which show that false-positive actions of AEBS have probabilistic tendency. Three indicators (False-Positive half-value, False-Positive half-value gradient and False-Positive zero-value) that can evaluate the effect of countermeasures for false-positive actions of AEBS quantitatively are proposed and its effectiveness are verified.

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The fatality rate of motorcyclists is much higher than that of four-wheeled drivers. In order to propose measures to reduce accidents involving motorcycles, we analyzed the causal relationship between the state variables under ordinal driving conditions of motorcyclists and the risk of collision at intersection using structural equation modeling and clarified that there is a correlation between lateral wobble and the risk of collision. We then proposed an active safety system that presents information on the amount of wobble to motorcyclists and confirmed that the system can reduce the risk of collisions in experiments using a riding simulator.

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Highly automated driving is one of the solutions to the problem of driver shortage in the logistics industry, and securing the acceptability of surrounding drivers is important for its spread. In this study, we examined the effects of the external Human Machine Interface (eHMI) of automated truck driving in the operational design domain on the acceptability of surrounding drivers. Visual behaviors, subjective evaluations, and driving performance were investigated in a scene where drivers encounter an automated truck at a junction using a driving simulator. As a result, the visual reaction time in the case with the eHMI was lower than that in the case without the eHMI. In addition, subjective evaluation values were improved by the eHMI. This suggests that the eHMI on the automated truck can be effective in improving the safety and acceptability of surrounding drivers.

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Co-electrolysis, which is the electrolysis of carbon dioxide and water vapor into hydrogen and carbon monoxide by supplying electric power to solid oxide cells, has attracted much attention because of its high energy conversion efficiency. However, since some carbon dioxide sources contain nitrogen and unburned oxygen, a system analysis of the effect of the concentration of these gas mixtures on energy efficiency was conducted. As a result, it was shown that the efficiency was greatly reduced when both nitrogen and oxygen were supplied at the same time, compared to the case where only nitrogen or oxygen was mixed.

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Impacts of transboundary air pollution from East Asia Domain and domestic air pollution in Japan Domain on air quality in Japan in 2050 were investigated by simulations using CMAQ. As a result, it was found that the domestic air pollution had an influence on the concentration of O3 in Japan during whole seasons, while the transboundary air pollution from East Asia had an influence on O3 in Japan in autumn and winter seasons. In the case of PM2.5, both of East Asia and domestic air pollution had an influence on the PM_2.5 concentration in east Japan, while East Asia air pollution had larger influence on PM_2.5 concentration than domestic air pollution in west Japan.

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The ambient conditions in the emission measurement test procedure for light duty vehicles are defined as an almost constant temperature (23 deg C) and humidity (50 %RH). However, in the real driving situation, the temperature and humidity are widely dispersed, for example, high temperature and high humidity during the rainy season, and low temperature and low humidity during the winter season. Even during a real driving emission (RDE) test, the temperature and humidity are fluctuated. In this study, several couples of ambient conditions have been adopted for the emission measurements and the results are discussed from the effects on the vehicle and on the emission measurement system.

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Particle Number (PN) emissions from three hybrid passenger vehicles with gasoline engine were measured under various ambient temperature (-7℃~35℃). Test was conducted with WLTC mode without Ex-High part. PN emissions were evaluated with methodologies of certification tests in Europe (23 nm and 10 nm). Increased CO and PN emissions were observed where the enrichment control appeared, such as first cycle of cold mode at low ambient temperature. Other emissions of PN were observed during warming up process. Both emissions exhibited dependence to ambient temperature. These impacts of ambient air temperature are particular in cold mode test and negligible in hot mode test.

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In this study, friction stir welding of similar and dissimilar materials was carried out using die casting aluminum alloy ADC12 and wrought aluminum alloy 5052 and 6061 to evaluate the tensile strength and to analyze the fracture of jointed materials. In ADC12 similar joint, the tensile strength was lower than that of base material. Joining efficiency was 86% and adequate tensile strength was obtained. Softening due to heat generated during friction stirring was not observed. The fracture location was the Stir Zone. The tensile strength of similar joint is lower than that of the base material due to the different shape and distribution of the Si phase in the Stir Zone. In dissimilar joints of ADC12with 5052 and 6061, joining efficiency was more than 80%. Placing a material with lower tensile strength at the Advanced Side will result in higher tensile strength than placing it in the Retreating Side. The fracture location of dissimilar joints was the softened point of the wrought aluminum alloy (5052, 6061), where the tensile strength of base material is lower than ADC12.

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Vehicle localization is one of the important technical factors in autonomous driving vehicles. Localization method using magnetic road markers (magnetic positioning system; MPS) meets the necessary precision, accuracy, and robustness for autonomous vehicle localization. We propose a concept to overcome some of the problems that the current MPS has. This includes using only one set of magnetic sensors, and a method where magnetic road markers are placed in grid-like patterns, enabling vehicles to take various routes. The proposed method was verified using simulation and data taken from experiments using actual vehicle, and it was able to accurately localize the vehicle.

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Calculating a target trajectory for driving is essential for an autonomous driving system. It can be obtained by numerical optimization which minimizes an objective functional including a deviation penalty from a reference path of a target lane. The reference path is often referred to as a centerline, and there was little discussion of a comprehensive method for its generation which takes into account various road geometries. Therefore we propose a method which calculates desired reference paths from a HD map. The method was applied to actual highway roads and was capable of creating smooth reference paths including complex road environments.

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Validation with several test methods called the multi-pillar approach is proposed in VMAD (validation method for automated driving) under UNECE/WP29/GRVA to ensure the safety of automated driving vehicles comprehensively. Significantly, public road testing is critical to ensure the safety of the automated driving vehicle in the actual operational design domain. However, there are concerns about the traffic scenarios encountered during the test. In this study, the traffic situations during public road testing are investigated according to the UNR157.

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