To investigate the reduction of fuel consumption in a downsizing gasoline engine equipped with a Variable Geometry Turbocharger (VGT), 1.6L VGT gasoline engine model was built with a Cooled Exhaust Gas Recirculation (EGR) system by using a 1D cycle simulation software (GT-POWER). As a result of comparing the conventional Waste-gate Turbocharger to a VGT in fuel efficiency of driving cycles (JC08 and WLTC), the potential to reduce the fuel consumption by the combination of VGT and Cooled EGR was found due to the decrease of pumping loss using a VGT.

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Although cooling loss reduction is one of the approaches to improve brake thermal efficiency in a diesel engine, it doesn’t only contribute to the brake thermal efficiency improvement but most of it converts to the increase in exhaust heat loss. The increased exhaust heat loss due to the in-cylinder cooling loss reduction is effective to enhance the effect of waste heat recovery. In the engine system considered with waste heat recovery system, brake thermal efficiency may be improved by the effect of in-cylinder cooling loss reduction and the effect of waste heat recovery at partial load.

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One of the issues involved in compression ignition combustion is the increase in combustion noise from engine mechanical systems caused by rapid combustion. When the fuel used is natural gas, with its high ignition temperature, the compression is increased relative to gasoline, so that combustion becomes even more rapid. The present research pursues the issue of noise by clarifying the distinctive features of combustion noise through tests focused on the two topics of stroke-bore ratio and engine structures deformation mode. From these results, we verified combustion noise trend and occurrence factor.

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A detailed chemical kinetic mechanism for n-tridecane generated by KUCRS, contains 1493 chemical species and 3641 elementary reactions. Reaction paths during ignition process for n-tridecane in air computed using the detailed mechanism, were analyzed with the initial temperatures of 650 K, 850 K, and 1100 K in the τ ₁ dominant, negative temperature coefficient, and non- τ ₁ regions, respectively. Based on full knowledge derived from the reaction path analysis, a reduced mechanism containing 49 species and 85 reactions, was developed and validated. The reduced mechanism includes C₃H₇, C₂H₅, and CH₃ as representative fragmental alkyl radicals, C₇H₁₄, C₃H₆, and C₂H₄ as representative alkenes, and C₃H₇CHO and CH₂O as representative aldehydes. Ignition delay times with different initial temperatures between 600 K and 1200 K using the reduced mechanism, and their dependences on pressure and equivalence ratio agree well with those using the detailed mechanism. The profiles of fuel, CH₂O, H₂O₂, and CO concentrations agree roughly with those using the detailed mechanism.

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The non-contact and time-series two-dimensional (2D) temperature measurement method has been developed using computed tomography-tunable diode laser spectroscopy (CT-TDLAS) to elucidate the engine combustion phenomena. 2D temperature were evaluated by H₂O absorption spectra measured inside an engine cylinder using a 16-path CT cell. The 16-path CT cell was installed between the engine head and engine cylinder without structural change of the single-cylinder engine. Wide-wavelength scanned multi-path laser beams were simultaneously introduced to the engine cylinder and simultaneous time-series two-dimensional temperature distributions were reconstructed to elucidate the engine combustion phenomena. It was demonstrated that time resolved temperatures of multi-laser path were measured at 0.1-4MPa pressure conditions and time resolved 2D temperature distributions were successfully reconstructed using a revised H₂O absorption data base.

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Zero-dimensional analysis with detailed kinetic mechanisms has been performed to elucidate the underlying chemistry of the Livengood-Wu integral which has been used to predict and analyze the knocking phenomena in spark ignition engines. Its predictive potential was ascribed to be the similarity between the concentration of the "pertinent reaction product (x)" in the original concept and the simulated logarithmic total concentration of hydroperoxides, log[total-OOH]. It was shown that the integral is a good indicator of ignition for periods before cool flames while the predictability significantly deteriorated for periods after cool flames.

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In diesel engines having heterogeneous in-cylinder temperature distribution, wall heat loss analyses of spray flame impingement region at the periphery of the piston cavity are necessary to consider the heat loss reduction and thermal efficiency improvement. This study examined a quantitative analysis of the local wall heat loss on spray flame impinged regions by high magnification combustion observation by using a single cylinder heavy-duty diesel engine equipped with top-view optical system. This high magnification and high-speed observation enable to measure the distance from the wall to the stabilized region of natural luminosity of flame which is valuable for quantitative analyses.

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Heat release rate controlling and simultaneous reduction in NOx and smoke emissions were achieved by using the new combustion system which is a single-cylinder heavy-duty diesel engine equipped with three injectors (multi-injector). However, it is revealed that the heat release rate by the side injector was slower than that of center injector especially at the end of combustion. In this study, multi-injection from the center injector was attempt for expanding operating range to a high-load operation in order to shorten the combustion period. Furthermore, the mixture formation and combustion process in the cavity were observed by a bottom view visualization system. By the combination of higher boost pressure and precise heat release rate controlling to suppress the maximum in-cylinder pressure in constant, which resulted in heat loss reduction together with brake thermal efficiency improvement, and simultaneous reduction in NOx and smoke emissions even in a high-load operation region.

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Oil drain holes of a piston affects engine oil consumption, but there is no theoretical guidance for optimal design. This study aimed for clarifying the effect of design of oil-drain-hole on oil behavior under the oil-ring to estimate mechanism for oil pressure generating. The oil pressure variations under the oil-ring in the circumferential direction was measured using a gasoline engine. An increase in oil pressure was found during down-stroke of the piston. The lowest oil pressure was found when the piston with four oil-drain-hole. Two holes set nearly front / near end of the piston-skirt showed relatively lower pressure.

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In this study, in-cylinder flow and turbulence characteristic induced by intake switching device, TCV (Tumble Control Valve) is investigated on a single cylinder optical engine with a transparent sleeve using high speed PIV. As a result of analysis, turbulent kinetic energy at the end of compression stroke increases by TCV. However it is clarified that an optimization of TCV is necessary because there is some cases which turbulence does not increase by some TCV specification. Since combustion duration on a metal multi cylinder engine decreases by optimal TCV specification, it is confirmed that TCV is an effective devise for enhancement of in-cylinder flow.

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The heat release rate and emission in dual fuel operation using natural gas and diesel fuel has been studied in conventional small diesel engine. High efficiency and very low emission combustion are obtained in the case of advanced injection timing and high ratio of natural gas condition. After that, the criteria for low emission has been investigated by analyzing the diesel fuel distribution using 3D-CFD. Finally, we have created the engine operation map for low emission combustion.

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Engine air path systems have a lot of constraints coming from hardware and actuator limits. In order to explicitly treat the constraints, we apply a reference governor (RG) to the engine air path systems. The RG algorithm optimizes a cost function that evaluates the degree of constraint satisfaction based on the gradient descent method. Experimental results using a real diesel engine show improvement in control performance with constraint satisfaction.

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Distraction due to thinking or reduction in arousal level makes a driver difficult to notice the surrounding hazard. Therefore, it is important to notify the surrounding hazard so that the driver can recognize it so quickly. This study is considering a system that informs a driver of spatial perception with the wave field synthesis to avoid traffic accident and the way to decrease effects of reflections to bring synthesized sound field to ideal sound field in a room of a car.

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The accuracy and reliability of FE models become more important to realize the virtual engineering. Thus, the quality of structural FE models such as white-body models is also required to be enhanced. From the investigation, it showed that natural frequencies derived by the simulation results of the general FE models are higher than experiment data. The drawing information is the basis of normal FE models construction, and it have issue to represent the experiment. The information from the production process like stamping effect can enhance the quality of the FE models. This paper describes the calculation results of stamping simulation have been applied to the FE models for NVH analysis. As the results, the gaps of natural frequencies between NVH analysis and the experiment can be closer with small errors.

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This paper introduces potential functions which represent path and velocity simultaneously in the case of avoiding parked car. The parameters of potential functions are identified by using driving data. Personalized driving characteristics are compared by the parameters. By using known parameters, the potential functions are applicable to the different environment and personalized driving characteristics are verified by experiment result.

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In previous research, we developed an algorithm for an Advanced Automatic Collision Notification (AACN) system that predicted the injury severity resulting from car and bicycle accidents and one for car and pedestrian accidents. The purpose of the present study was to develop an injury prediction algorithm for car and motorcycle crashes. Two algorithms were developed using macro data from the 880,000 motorcycle (MC) accidents in the ITARDA database that occurred between from 2005 to 2014 in Japan. The first algorithm, MC model 1 uses crash details such as motorcycle travel speed and crash direction as well as motorcyclist information such as age of rider and helmet usage. The second algorithm, MC model 2 also uses the partner crash car information such as travel speed and crash direction. MC model 2, which uses both motorcycle and car travel speed information is a better prediction algorithm. The results indicate that for a 10% rate of under triage, the threshold is 6.4% for MC model 2.

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The aim of this study is to develop the shared control system between ADAS and a driver. In this second report, the proposed system which combines haptic steering guidance system and Direct Yaw-Moment Control (DYC) is investigated in the scene requiring risk predictive driving. The experiment was conducted by using the driving simulator. Thirteen elderly drivers whose average age was 71 years old were employed. The effectiveness of the proposed system is evaluated in terms of vehicle handling and vehicle dynamics by the experiments. Furthermore, the parameters of driver model are identified using the above experimental results, and the effectiveness of the shared control on the change of the maneuver characteristics are evaluated.

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Since elderly drivers tend to cause crossing collisions, the most frequent automobile accidents, it is required to clarify the principal causation of these mischances in our aging society. In order to compare elderly drivers’ behavior with that of expert drivers paying special attention to the number of collisions with bicycles, drivers’ safety confirmation activities and their foot position, we established a simulation program based on the experimental data obtained on the test courses.

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In a Level 3 automated driving system, sometimes the driver may be asked to perform non-driving-related tasks because of a lack of engagement in the driving task. We conducted a driving simulator experiment to investigate the driver’s behavior when accepting the system’s request for manual driving under distracted condition by non-driving-related tasks. "Radio hearing task" and "text input task" were set for non-driving-related tasks; in addition, "no task" was set to a control condition. There was a tollgate where the limit of the automatic driving systems because of reached to the end of lane markers. The timing of starting brake was significantly later and maximum brake pedal force was larger in texting. Almost all drivers could resume driving from system, however there was one collision occurred in a texting condition. We suggest that the method for generating the request for deeply distracted driver should be considered.

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The present study aims to clarify the effect of visual and cognitive distraction on drivers’ risk management in a carfollowing situation. The primary task consisted of following a lead vehicle at a constant headway while that vehicle changed speed according to a predefined rhythm. The secondary task, which involved using a surrogate user interface, consisted of four different tasks to assess interference with the driver’s risk assessment during driving. To achieve the objective, we measured driver’s objective and subjective risk assessments by conducting a field experiment on a test track using 36 participants. The results suggested that the smallest effects on driver’s risk management were for the auditory stimuli and verbal response. It could be required to develop human machine interface to minimize driver’s risk management and maximize safe driving state.

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The purpose of this study was to clarify ‘peace of mind’ in relation to driving, from the perspective of clinical psychology. We inquired normal drivers and less frequent drivers about the types of anxieties they experienced when driving, because anxiety is known to be the opposite of peace of mind. We categorized the anxieties expressed by the drivers. Then, we interpreted these categories by using clinical psychological theories. Based on the results, we have discussed possible measures for reducing anxieties related to driving.

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Traffic accidents on an intersection with a stop sign caused by elderly drivers have been increasing. The effect of changes associated with aging in physical functions and cognitive functions is pointed out as one of the reasons. In this paper, we conducted the experiment that the drivers including elderly go through or turn right at an intersection with a stop sign on different sight distances using a driving simulator, and analyzed the relationship between the collision rate, the behavior and the biofunction of the drivers.

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In order to develop products which satisfy various demands for a limited period, shape optimization technology by using Adjoint method has been developed. In this study, we developed CFD calculation technique by using Immersed boundary method which does not require mesh to regenerate for modified shape, in order to operate the shape optimization process automatically. Present technology was applied to design of engine intake port to achieve a balance the maximization of flow rate and that of tumble vortex. As a result, the optimized shape which has superior flow performance compared to the conventional design shape was obtained efficiently.

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This paper considers a model predictive control method for eco-driving with a preceding vehicle using binary variables to represent traffic signal. In the control method a motion of preceding vehicle is dealt with as inequality constraints. By the inequality constraints the controlled vehicle can run by using appropriate acceleration/deceleration for eco-driving. Computer simulation is carried out to show the effectiveness of the proposed control method.

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