A PCI (Premixed Compression Ignition) combustion concept which achieves simultaneously low emissions and fuel consumption has applied to a new developed engine whose compression ratio is extremely low value 14.0. The robustness improvement of the fuel consumption, emissions, and noise in transient condition, which was one of the issues of PCI combustion for practical use, has achieved by means of the following techniques: -Model based ignition timing control, in which the ignition delay was predicted by Arrhenius type extended empirical formula with the model constants by DOE, and Livengood-Wu integration. -Restriction of spray mixture homogeneity by multi-stage injection.

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This paper describes the combustion characteristics and fuel properties of gas oil blended with fatty acid 2-ethylhexyls derived from palm/coconut oil. In this study, lauric acid 2-ethylhexyl (2H-12) having the cetane number of 66.7 and the pour point of -32.5ºC, and palmitic acid 2-ethylhexyl (2H-16) having the cetane number of 73.1 and the pour point of -2.5ºC are blended into gas oil to improve ignition quality and/or cold flow property. Experimental results of engine bench tests show that by blending 2H-12 or 2H-16 into gas oil, the ignition delay is shortened and premixed-like combustion immediately after the auto-ignition is suppressed. As the result, the thermal efficiency together with nitrogen oxide emissions are improved. However, the short ignition delay obtained at the blend ratio of 20vol% leads to increase in smoke emission.

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A fuel design concept for an HCCI engine to optimize a profile of heat release and achieve a robust ignition process has been proposed and applied to design the optimal methane-based blend. According to results from detailed chemical kinetic computations where ignition process chemistry of each component of the natural gas was analyzed, ethane indicates a low ignitability close to that of methane with an initial temperature below 800 K, but a higher ignitability close to those of propane, n-butane and isobutane with an initial temperature above 1100 K. And ethane indicates a higher heat release rate than those of the other components in a late stage of an ignition process. According to results from engine operating tests with a compression ratio of 28.0 : 1, a dual-component fuel of the main component of methane and the sub component of ethane demonstrates a lower COV of IMEP than those of the other dual-component fuels with the sub components of propane, n-butane and isobutane, when the timing of 10 % heat release is set at the same crank angle in the expansion stroke.

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In recent transmissions, enhanced fuel efficiency considerations call for further weight reduction without sacrificing reliability. This extends to the differential cases used in many transmissions, where lighter designs that ensure the required performance are expected. This paper proposes a method relying on CAE to predict the maximum load torque under which rotational loosening does not occur when accounting for the elastic deformation of the differential case. In addition, this paper identifies the relative sliding of the screw surface and contact surface and presents design guidelines for reducing the weight of the differential case.

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This paper describes a dry multi-plate clutch, housed in the motor and free of drag torque and a flywheel damper that reduces engine start noise produced by the starter. These components have been newly developed for use in a one-motor two-clutch hybrid system. The hybrid motor, clutch and flywheel damper are designed to be installed in the space occupied by the torque converter of a continuously variable transmission (CVT) used on front-wheel-drive vehicles.

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In order to improve fuel economy of heavy duty vehicles at actual driving condition, new system concept of hybrid electric heavy duty vehicle was proposed at 1st report. The key technology of this system is the electric-booster. In this report, engine performance and exhaust emissions was investigated using 4 cylinder diesel engine equipped with electric-booster. Test condition of this engine system was high boosted and wide range EGR. This test result of fuel consumption and exhaust emissions was improved at the same time. And, electrical power of electric-booster was able to be supported by regeneration energy of medium duty hybrid electric vehicle, when regeneration energy of this vehicle was investigated by chassis dynamometer equipment.

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In order to realize a substantially eco-friendly tire offering appreciable driving safety and drivability, development of a next generation ecology tire technology beyond common knowledge in terms of a tire dimension has extensively been done. Through detail investigations of the size and inflation pressure effects considering optimum tire deformation around contact patch, the conceptual next generation size tire has achieved ultra-low RRC performance and appreciable F&M characteristics such as high CP/CF for drivability and braking capability for driving safety. As a tire manufacturer, we would like to propose the newly designed conceptual tire for next generation vehicles.

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At the starting run after changing the load of actual truck, the natural frequencies of bouncing and pitching are measured and then judged referring to the natural frequencies of the ride model. Then, sprung mass, moment of inertia, gravity center location and each axle loads are estimated by the ride model equations also. Lateral dynamics model adopts the estimated parameters so that suit to the load change. How to identify the lateral dynamics model to load change and then how to estimate the model parameters by ride model are explained including the test method.

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A new yaw-moment control method which generates enhancing/stabilizing moment in accordance with vehicle lateral jerk divided by vehicle speed was analyzed. The analysis using the linear plane bicycle model showed the natural frequency of the controlled vehicle was increased, however, damping ratio was decreased. The improvements of yaw response for especially over-steer vehicle were confirmed. Moreover, the control improved the stability by detecting derivative of disturbance force from vehicle lateral jerk.

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An analytical model for transient cornering properties is proposed for a small slip angle. The model, which is based on the Neo-FIALA model, approximates the deformation of a cornering tire by a combination of the shear deformation of tread rubber, the in-plane belt deflection and the out-of-plane sidewall torsion, and leads to a second-order transfer function for side force. The steady gain and delay time constant of transfer function are described by the equivalent tire-part stiffnesses, the concrete values of which can be determined from the measured load-dependence of steady cornering for a test tire.

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H-point and backset are used as the basis for placing dummies in car crash tests. There is some range of variation in H-point and backset mostly due to tolerance in dimension and/or material property. The paper describes a finite element (FE) model of H-Point Manikin developed for analyzing the variation of H-point and backset in actual measurement. Parametric studies were conducted to identify significant factors for variation, and to examine the effectiveness of the factors on reducing the variation range of H-point and backset.

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The impression relationship between automobile body colors and door closing sounds is researched by both subjective and objective evaluation methods. First, impressions of heavy, clarity and comfortable sensations for the evaluation colors and sounds are observed by SD method. Next, stress reduction by the effect of the colors and the sounds matching is observed by monitoring saliva amylase. Further, the impression relationship is suggested based on structuring the visual and auditory matching model considering color chromaticity and above evaluations.

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This paper describes a possible cause of discomfort in the abdomen region of an occupant due to vibration at a frequency of 4 Hz. A human body FE model, THUMS Version 1, was used to explain the skeletal motion. The pelvis was rotated by a vertical load mostly acting to the ischium from the seat cushion. The abdomen part was compressed with the spine moved back and forth. When the vertical load to the ischium was decreased by changing the seat cushion property, the magnitude of pelvis rotation and the abdominal compression were reduced.

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We developed the road surface shape estimation method used with cameras and active lights. In this paper, we applied the method to preview feed forward skyhook control of the electric active stabilizer suspension system, and compared with the laser displacement sensor controller reported in our previous paper. The sensing and ride comfort performance of system are verified.

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High frequency of fatal head injuries of the elderly is one of the important issues in traffic accidents in Japan. While a human head/brain FE model is a useful tool to investigate head injury mechanism, there has not been such a model that reflects the age-related changes of the brain. In this research, to get the basic knowledge to develop a head/brain model capable of representing injury mechanism of the aged brain, influence of various intracranial changes on various intracranial responses relating to brain injuries was clarified by parametric study using human head/brain FE model.

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Although the evaluation of pedestrian safety performance of vehicles required by regulations and new car assessment programs (NCAP) must have contributed to the reduction of pedestrian casualties, their real-world relevance has not been fully clarified. One way to develop further understanding of real-world pedestrian accidents is to reconstruct a variety of accident scenarios dynamically using computational models. Investigations using a simplified vehicle model that allows changes of vehicle stiffness characteristics in a systematic manner are effective means of reproducing various types of accidents. The baseline simplified vehicle model developed in this study consisted of four parts: the windshield, hood, bumper, and lower part of the bumper. The hood and windshield with relatively large areas were divided into smaller areas, and different stiffness characteristics were assigned to them. In addition, models without dividing the hood and windshield were developed for comparison purposes. These simplified vehicle models were made to collide at 40 km/h with a human model, and the pelvis and lower limb injury measures and full-body kinematics were compared. The results showed that the division of the hood and windshield along with the application of local stiffness distributions significantly improved the representation of pedestrian full-body trajectories and pelvis and lower limb injury measures.

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Corresponding to the increasing need for the protection of elderly people from traffic accidents, the authors have been developing age-specific human FE models capable of predicting body kinematics and skeletal injuries for younger adult (35y.o.) and the elderly (75y.o.). The models have been developed and validated part by part referring to the literature and then integrated into whole bodies. Validation had been conducted in order of single bones, components and whole body. Whole body kinematics in frontal impact had been validated against the PMHS frontal belt restrained sled tests series, resulting in good biofidelity scores. In this study, the models were validated for lateral impact. The models were validated against several impact tests of body regions from ISO-TR9790 and against recently published full scale lateral sled tests for whole body kinematics. In most cases, the results showed good biofidelity of the models. Capability of the rib fracture prediction was also discussed.

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This study focuses on sudden crossing behaviors of pedestrians in urban narrow roads, which is one of the most unsafe behaviors in the viewpoint of traffic safety, setting its final goal to develop an active safety technology to prevent pedestrian accidents. In this paper, hazard-anticipative driving behavior in a narrow road is formulated by utilizing the pedestrian sudden crossing behavior model which the authors proposed in the previous study, and a safety index is proposed based on the formulation. From comparisons between the proposed index and the real driving data obtained through real car experiments, the usefulness of the proposed index is shown.

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This study clarifies adaptation of previous driver's occupant injury prediction model to front seat and rear seat passengers using Japanese accident data. In results, the driver's injury prediction model can estimate passengers in front seat and rear seat. However, the accuracy for predicted injuries of front seat and rear seat passengers is somewhat worse than that of drivers in higher delta-V. Furthermore, some outlier accident cases indicate that improper seat belt usage increases injury risks for both passenger seats, especially for short-stature female passengers. It is considered that there are various conditions of seating position and seat belt usage for passengers; therefore, it causes dispersion of their injury risks.

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This paper describes an investigation of factors influencing driver’s fatigue while driving for a long time and a classification of drivers based on the obtained factors that are related to a sensitivity to fatigue during the long-trip drives. We conducted questionnaire survey which included candidates of the influencing factors on the driver’s fatigue on long trips, changes of driver’s conditions related to the driver’s fatigue, and compensatory behaviors after the driver feels the fatigue. The factor analysis suggested five factors: careful and frequent operations, deceleration due to movements of other vehicles, disturbance of concentration on driving operations, bad conditions of road environments, and bad physical conditions. The cluster analysis of the factor scores indicates two main types and six subgroups of drivers sensitive to the fatigue resulting from long-term driving.

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This paper describes an effect of the arousal maintenance method based on percussion performance. An experiment to validate this method’s effect was performed under the following experimental conditions: Condition 1, “Only warning”; Condition 2, “Cold wind after warning”; and Condition 3, “Percussion performance after warning.” After the ratings for “Drowsiness level” and “Effort against drowsiness” were evaluated by two trained raters, an “Arousal maintenance time” was calculated. “Arousal maintenance time” in Conditions 1 and 2 was about 17 min, while “Arousal maintenance time” in Condition 3 was about 46 min (2.7 times the other conditions). Thus, motivation for the percussion performance may have caused the arousal maintenance effect.

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An empirical model of driving behavior on a non-signalized intersection without right-of-way was derived through naturalistic driving study. Twenty four intersections were selected for road experiments and ten subjects drove a vehicle on each intersection twice a day for six straight weekdays. The vehicle was well equipped with instruments for measuring and recording both vehicle’s and driver’s behavior. We proposed characteristic variables to describe driver behavior on non-signalized intersections: deceleration starting TTC, deceleration ending point, speed at deceleration ending point, crawling occurrence ratio, crawling distance, crawling period, acceleration starting point, speed at acceleration starting point, and acceleration. Influences on these characteristic values of the following static properties of intersections were tested using ANOVA and multiple regression analysis: turning direction, left sight visibility, and right sight visibility.

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This paper describes the numerical analysis of unsteady aerodynamics of a car in dynamic motions to clarify the effect of adding aerodynamic parts on the unsteady aerodynamic response of a car. Large-Eddy simulations with moving boundary method were carried out. In this study, forced pitching oscillation or lane-change maneuvering was imposed on a simplified shape model of car with or without the aerodynamic parts, and unsteady aerodynamic forces and moments acting on the car model were investigated. As a result, the aerodynamic parts contribute to enhance the aerodynamic pitch and roll damping by rectifying the wake of front wheel.

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The purpose of this paper is to clarify the influence of the blade surface area on the fan performance. RANS calculations were employed on the various blade geometries and the predictive accuracy was ensured based on the comparison with the measurements of P-Q and T-Q characteristics. Then, a new indexφλ ^*'λ were proposed and defined to reveal the impact of blade surface area. As a result, it was found that the fan performance depended on the total blade surface area when the geometries on the cylindrical section were designed in a similar figure. This means that, as far as major parameters of blade such as number of the blade, span, chord and attack angle are designed in the same condition, the blade shape such as the forward, backward and straight does not have significant influence on the fan performance. Accordingly, for designing a cooling fan, lower width and larger area of blades will be effective to meet limited space as in the engine compartment of an automobile.

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Mass emission of gas components from vehicles are generally obtained by Constant Volume Sampling (CVS) method, though this method measures the averaged mass emission over test cycle. Information of instantaneous mass emission is useful for engine control. A flow rate measurement using CO₂ as a tracer can be a method to calculate the instantaneous mass emission. In this study, two wet base CO₂ analyzers using heated NDIR have been applied for this CO₂ tracer method. In the comparison with CVS-SAO method, the wet base CO₂ analyzers showed better results for exhaust flow rate measurement than dry base CO₂ analyzers.

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It was investigated whether the urea SCR system has sufficient effect of NOx reduction or not under driving on the ordinary road. The driving test was conducted by putting the on-board FT-IR gas analyzer on the light-duty truck equipped with urea SCR system. Functional performance of that system was analyzed by continuous measurement data of the concentration of NOx, N₂O, etc. and exhaust-gas temperature. As test results, it was revealed that the NOx reduction effect cannot be sufficiently exhibited if the SCR catalyst is not heated to the activation temperature, and phenomena enlarging the N₂O emission during cold-start was found.

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Firstly, we proposed the methods to evaluate the changes of driving behavior and to estimate the reduction of carbon dioxide emission by the implementation of eco-driving in daily passenger car use. Secondly, the methods were applied to the driving data which were collected through the society experimental trial in Hyogo prefecture, Japan. The results show that after the eco-driving training course, the eco-driving were implemented by five trial subjects out of nine. The maximum carbon dioxide reduction effect of 12.5 % was estimated using the engine mapping.

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Fatigue tests were conducted on arc welded lap joints made of 440MPa grade high-strength hot-rolled steel sheets under a repeated two-step variable amplitude loading condition. The cumulative damage (D) decreased when increasing the difference in the loading amplitude between the high- and the low-level loadings. Moreover, D increased with the increase of the number of cycles at the low-level loading amplitude, under the condition that the low-level loading was below the fatigue limit. Furthermore, the EBSD observation nearby cracks was conducted and revealed that D might be in correlation with the amount of concentrated strain at the crack tip.

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In design of a controller for ACC, the control algorithm should guarantee the string stability, which means that amplitudes of the spacing vibration should not get amplified as they propagate upstream from vehicle to vehicle. In the ACC where a controller uses information of an inter-vehicle distance and a relative velocity, it is difficult for heavy-duty vehicles to guarantee the string stability at time-headway control with short headway time due to their slow response characteristics of acceleration. This study proposes the longitudinal control algorithm for CACC (Cooperative Adaptive Cruise Control system) using information of the preceding vehicle obtained by the inter-vehicle communication. In the proposed controller-vehicle system, the string stability is guaranteed regardless of feedback gains and the propagation of vibration of the preceding vehicles’ accelerations is effectively attenuated. The proposed control is validated by simulations and experiments using four heavy-duty vehicles.

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A study was performed to examine model-based calibration, using a diesel engine’s un identified plant model, to calibrate the control values of the idle engine speed control under transient condition. In order to calibrate the control values, the parameter design method of Quality Engineering was applied. As a result, not only it being able to provide control values that have adequate controllability, but was useful to achieve well designed control logic by analyzing the control values changing process of the repetitive parameter design.

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