In this research, the effect of hydrocarbon species and concentration on oxidation reaction in DOC was investigated, experimentally. When concentration of HC become higher, temperature at which oxidation reactions start is lower and the reaction rate for temperature increased. In addition, influence of the HC density on temperature at which oxidation reactions start increase rate and reaction rate become slower when the Carbon number of HC increased. We expressed these reaction mechanism from relations structure of HC and the adsorption form.

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Predicting an engine warm-up process is effective for evaluating fuel consumption and exhaust emissions in the cold start condition with the vehicle simulation and on-board diagnosis of a coolant temperature sensor used for engine control. In this study, a prediction method of coolant temperature in the engine warm-up process was developed by using a simple calculation model and quantified total heat mass of the engine system based on experimental data. In addition, the method was validated under various conditions by an engine test cell and a vehicle test cell experiments.

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For enlarging the knock limit of SI engine to realize further increases in thermal efficiency, the authors proposed a simple method to promote local heat transfer through moderate enhancement of the gas flow at the point of origin of knock, in order to lower the end-gas temperature and by this means retard auto-ignition timing. The use of the proposed method advances the combustion phase 2.2 degree without increasing the discharge of unburned exhaust components, and this advance in the combustion phase increases IMEP by 17.2 kPa.

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The present study investigated the effects of combining supercharging and EGR in the operation of a small single cylinder DI diesel engine. The experiments used coconut oil methyl ester (CME) and a blended fuel with 60% (mass) CME and 40% 1-butanol (represented as CMEB). The boost pressures were varied from 100 kPa (naturally aspirated condition) to 130 kPa with a Roots blower type supercharger and the oxygen concentration of the intake air were changed from 21 to 16.4% using cooled EGR. The results show that the trade-off relation between the NOx and smoke emissions of the CMEB fuel improved remarkably at high EGR conditions with supercharging.

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Floating liner method is useful for measurement of piston friction force in a reciprocating engine. Floating liner device should be designed considering the purpose of the measurements. Five kinds of floating liner device using two types of load cell were compared in this study. Load washers of piezo-electrical type were employed in the floating liner devices for a water-cooled gasoline engine, an air-cooled gasoline engine and two kinds of diesel engine and 3-component force sensors of piezo-electric type in the device for a diesel engine. The features of those devices were described. The suitable device for each purpose of measurement for piston friction was also discussed.

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The models of spark channel elongation and restrike for 3D CFD are developed to predict the ignition process of SI engines with super lean burn. The model is developed according to the proposed models, such as AKTIM (Air and Kernel Tracking Ignition Model), sparkCIMM, and comprehensive model proposed by Lucchini et al. In this study, the models are modified in terms of the tracking characteristics of the spark channel for the gas velocity, the resistance of the secondary-circuit, the spark channel formation at the restrike. The model is validated using the noncombustion experiment with constant volume vessel. The results of zero-dimensional simulation show that the time from the start of spark to the first restrike can be predicted, although some model constants are need to be improved. Furthermore, it is found that the temporal change in the electric energy into the gas can be estimated in this model. Then, the models are incorporated into 3D-CFD code (HINOCA), and it is confirmed that the spark channel elongation and restrike can be predicted.

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Measurement accuracy for oil film thickness were improved to analyze lubrication conditions on the piston skirt. Clear oil film pictures which were able to distinguish between hydrodynamic area and boundary area were obtained. The influence of skirt surface roughness for oil film thickness, and influence of direction of roughness on adhered oil volume at skirt were clarified by analyzing these oil film pictures and improved captured pictures.

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This paper presents a novel topology for variable leakage flux machines(VLFs) with inverted arc shape magnet, which are designed to change magnetic flux linkage for driving cycle efficiency improvement. The proposed topology provides additional degree of freedom on leakage flux path layout, then allowing higher power capability due to lower q-axis inductance. It is shown by FEA that the speed-torque characteristic and the efficiency of proposed topology can be improve.

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This paper proposes a magnet temperature estimation method for Interior Permanent Magnet Synchronous Motor (IPMSM). The method uses high frequency impedance (HFI) that depends on magnet temperature variation so that magnet temperature can be estimated without any temperature sensor. In addition, a novel motor structure, which has thin conductor attached to magnets for improving sensitivity of HFI variation, is proposed. The benefit of proposed structure is evaluated with a theoretical model and finite element analysis.

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A mechanism of nozzle freezing lock phenomenon at hydrogen refueling stations is investigated. Hydrogen filling using a pre-cool system can cause a nozzle freezing lock problems. In those cases, the nozzle cannot be disconnected normally after filling. In this study, a simulated pre-cooled hydrogen filling tests were performed to clarify the mechanism of the nozzle freezing lock phenomenon. It was observed that the nozzle was not able to be disconnected appropriately when the condensed water was frozen in the nozzle. Using a cap covering cold connection part of the nozzle is effective to prevent from the nozzle freezing problem.

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Two opposite concepts of BE bus (battery electric bus), “Short-range Frequent-charging type” and “Night-charging type” low-floor buses were designed and evaluated. First, considering the current technical level of battery and charger, we conducted the optimal design of both types. Then, to fully replace diesel buses which are under high-density timesheet in urban areas, the expected performances of onboard equipment were clarified.

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In order to reduce CO₂ emissions and solve the issues of Electric Vehicle, AI-EV (Air-Conditioner Integrated Electric Vehicle) has been developed. In the AI-EV, power source for operating an air-conditioner is combined with a generator, and both of them are driven by a small engine. In this paper, the authors have designed AI-EV and evaluated the effects that applied AI-EV to an energy community integrated with solar power, water heater and Electric vehicles. As the results, it was clarified that the leveling ability of the power system fluctuations, CO₂ emissions and economic efficiency are superior to those of the conventional systems.

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The study described in this paper aim to further enhance the estimation accuracy of the suspension stroke velocity using the vertical acceleration sensor on the sprung mass. The effectiveness has been already confirmed that the observer model is included the nonlinear characteristic of the semi-active damper and the observer feedback gain is scheduled by previous studies. However, the observer can not estimate high frequency over the body resonance point. To solve this problem, in this paper the observer is also included the hysteresis of the damping force. The effectiveness is verified by carrying out simulations and experiments.

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The concept studies by driver's sense are absolutely necessary at early stage of development of Personal Mobility Vehicles (PMV), which have totally different mechanism from current cars. The purpose of this work is to make clear the requirements to Driving Simulators (DS) in order to study tilting type PMV. Then we prospect future PMV study by immersive DS with stereoscopic vision of five large screens.

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This paper describes a way of applying 3D spot weld model to vehicle crash model. At first, new 3D spot weld model is developed by optimizing number of elements per one spot weld model for reducing calculation time. Secondly, an automatic 3D model creation tool is applied for reducing model creation time. Additionally, a method of inclusion welding simulation results in crash CAE model is applied. Finally, new 3D spot weld model and an automatic creation tool are applied to a vehicle crash CAE model.

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RDE(Real Driving Emissions) will be mandatory soon for emission regulations. PEMS(Portable Emission Measurement System) is one of existing methods to measure RDE with real test vehicle. Otherwise, some of negative aspects of PEMS are time consuming and costly method. This paper presents a possibility to use more effective way with CAE technology regarding the RDE. This study aims RDE testing with virtual environment and analyzes which parameters in some boundary conditions is most effective to RDE. Fuel consumption was estimated by this method as 1^st. applied performance. The results show this prediction method, using virtual test driving tool, is very effective for vehicle powertrain R&D. This paper also shows a verification of this simulation result by real driving with the same vehicle on the same real route.

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Since the traveling sound of an electric motorcycle is smaller than that of a gasoline motorcycle, pedestrians may not be able to easily recognize the traveling sound of an approaching motorcycle. We conducted a running test of a typical electric motorcycle sold in Japan to determine the distance needed for pedestrians to recognize its approaching sound. Further, the distance traveled from the occurrence of a hazardous event until the riders stopped their motorcycle was estimated in order to consider the measures necessary to ensure safety.

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Safety and acceptability are main concerns in the design of driver assistance system. In fact, these two requirements sometimes may conflict with each other depending on the situation and driver. This conflict is more emphasized particularly in the case of considering elderly driver. In order to solve this problem, this paper proposes a new drivervehicle driving assistance scheme, a ’supervisory interventional control‚ which consists of model predictive constraint satisfaction and multimodal human-machine interface. The proposed driving assistance scheme enables us to realize the safety without loosing acceptability.

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This study discusses the lane-keeping-assistance system for multi-articulated vehicles. The lane-keeping controller is designed by considering linear combination of the lateral displacement of the tractor and the relative yawing angle between the tractor and the backward trailer. The effects of the assistance system are evaluated by examining computer simulation with the driver-vehicle system which consists of the multi-articulated vehicle model, the lane-keeping-assistance system and the driver model. The assistance system improves the lane-keeping performance and reduces the driver’s steering effort under the lateral disturbance.

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A relation between velocity of a vehicle and its image on a retina of a pedestrian is described based on geometrical optics. Displacement of a vehicle position is decomposed into the tangential and the normal component according to the two-dimensional rotating-frame. The tangential component directly contributes to the perception by the retinal image, while the normal component indirectly contributes by changes in the visual angle through size constancy. It is shown how the magnitude of these two components depends on eye height of a pedestrian, frontal projected area and velocity of an approaching vehicle.

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The study focused assistance systems on stop intersections for elderly drivers. The three-step assistance system, giving ‘advisory ’, ‘warning’ information and brake intervention, was evaluated in the JARI proving ground. The control logic of the system was renewed depending on the results of the past study. The results indicated the new logic improved drivers’ acceptance of the ‘warning’ phase as well as ensuring the effectiveness of the system. The deceleration timing became earlier and approaching speed became slower when the system applied. The results also clarified the timing of the brake intervention should be determined depending on the visibility of intersections.

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The atomization phenomena of the fuel spray are known to be affected by flow conditions and cavitation inside the nozzle hole. Generally, it is known that bubble nuclear number increases with the increase in superheating degree on the liquid. So, the defining equation of cavitation inception is extremely important. In this report, bubble nucleation model was incorporated in commercial code of Star-CCM+ scheme which set bubble nuclear number of uniformity. And it was verified that the increase of bubble nuclear number affect the energy generated with cavitation bubble collapse.

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Modeling that high stresses exist in the inlet and outlet flange pipes of the muffler caused by the vibration of a moving vehicle, bending fatigue strengths of the welded joint samples of two types were defined through fatigue experiments. The factors that caused fatigue to failure such as the welding bead shape and metallographic structure were identified through the local stress measurement, FEM stress simulation, microscopic observation and SEM-EDS composition analysis. The shape effect was 17% and the material effect was 14% on the fatigue strengths resulted from the differences of the weld shape and the microstructure.

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For improvement of fuel economy of a gasoline engine, EGR usage or stop-start sequence are increasing. Under any condition, a precise control of an air fuel ratio(AFR) is required to optimize the purification efficiency of an exhaust gas. Recently, a model predictive control(MPC) using a nonlinear model was paid attention for an accurate control. This paper experimentally investigated an application of MPC using a linear model, but it has two inputs for control and disturbance. On account of predicting the disturbance effect successfully, AFR control using MPC satisfied good performance with some robustness.

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In this study, a driver model with feeling of risk in forward view, proposed in 1990s, is applied to an automated driving controller aiming at realizing comprehensible display of decision of the system for the driver and individual adaptation. The proposed automated driving controller is designed based on the hitherto known model adding basic path information, feeling of risk to curvature and variation of allowable risk according to velocity to control a steering angle and velocity reasonably along a complicated course in a campus site. The relationship between driving behavior by the control and control parameters are evaluated by simulation. Validity of the simulation results and feasibility of the control are confirmed by experiments.

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Lane keeping assist (LKA) needs to make its target trajectory close to the driver’s intention for safety and comfortableness on local roads. In this study, a method for LKA is proposed to realize individual adaptation. The system’s trajectory is generated by solving a constrained optimization problem, and the parameters of its evaluation function are tuned based on the driver’s trajectory to decrease uncomfortableness for the driver. The proposed LKA is evaluated by experiments. The experimental results show that the drivers steer the vehicle with lower torque after adaptation.

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