A simulation to predict friction loss in timing chain was established. To predict action and friction of every chain link, the link by link model was used for the imulation. Using this simulation, the detailed distribution of friction in chain system and the behavior of chain friction in time domain were predicted, and the study to reduce friction loss of chain became to be able to perform.

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The two-stage and sequential turbocharging strategy was proposed in order to achieve both higher torque at low engine speed, and better fuel consumption at low and high engine speeds. According to results of simulation and engine experiments, the improvement in fuel consumption was obtained at both low and high engine speeds by using this turbocharging strategy. On the other hand, although fuel consumption at low engine speed was further improved by using low-pressure-loop EGR, fuel consumption at high engine speed was deteriorated because of the seriously increased exhaust back pressure.

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In-cylinder CO distribution in diesel combustion was measured using two-photon excitation CO-LIF. The results obtained with CO-LIF were used to validate the accuracy of a numerical simulation. The measured location of the dense CO gas cloud, as obtained by the LIF measurement, agreed closely with the results of the simulation. The major source of the CO emissions under low-load conditions is the over-diffusion of the pilot sprays, while that under high-load conditions is the shortage of oxygen in the rich regions at the flame front.

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A new ignition-combustion concept named PCC (Plume Ignition Combustion Concept) is proposed by the authors in order to reduce NOx formation under high engine output operating conditions minimizing tradeoffs on output power and thermal efficiency. In this study a laser shadowgraphic visualization of propagating flame and jet in the combustion chamber was applied to understand the condition and behavior of the hydrogen jet which affects NOx formation and thermal efficiency. As a result, understandings such that distorted geometry of propagating flame indicates low entrainment of air to hydrogen jet, resulted in low NOx formation but low thermal efficiency. Increased cooling loss caused by impingement of propagating flame to piston wall is another factor obtained by visualization of propagating flame.

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Homogeneous Charge Compression Ignition (HCCI) combustion and effective use of gaseous fuels have attracted much interest as means of obtaining cleaner exhaust gas with a lower carbon content from internal combustion engines. In this study, the effects of the fuel type on ignition, combustion and engine performance characteristics were investigated experimentally and by chemical kinetic simulations using blended fuels of dimethyl ether (DME) and methane or DME and propane. The results showed that the blended fuel of DME and methane produced two-stage primary combustion, depending on the operating conditions, which had the effect of moderating combustion. With the blended fuel of DME and propane, ignition was delayed, making it possible to moderate the rapidity of primary combustion. It was also observed that propane had a larger effect than methane on suppressing the low-temperature oxidation reactions of DME.

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In order to predict for more real-world engine operating conditions such as ARTEMIS driving Cycle, a new spray model has been implemented in the 0D-cycle simulation to account for the spray-to-spray interaction in swirl direction, which interferes in air-entrainment into the sprays. Furthermore, NOx reduction models have been newly introduced in addition to the standard Zeldovich mechanism to account for NOx reduction process, which plays significant roles in richer and higher temperature conditions. Those new models remarkably improve the predictability of combustion characteristics all over operation points, and ‘virtual engine calibration′ becomes more realistic with the simulation proposed in this study.

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The effects of chemical structure on the ignition delay time (IDT) have been investigated by detailed chemical kinetic simulations. IDTs were calculated for stoichiometric and homogeneous fuel/air mixtures of all C3-C10 alkane isomers under the adiabatic constant-volume condition. From the variations of IDT with chemical structure of the fuel, the following trends have been identified with some exceptions for lower alkanes; IDT decreases with the length of main chain while it is unchanged by the side-chain length, IDT increases with the numbers of tertiary and quaternary carbon atoms, the latter of which shows larger effect than the former, and IDT is elongated especially when the branchings occur at adjacent carbons. These effects of the chemical structure are pronounced especially under the low-temperature oxidation conditions.

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In this study, the effects of the fuel type on multi-stage heat release characteristics in a supercharged Homogeneous Charge Compression Ignition (HCCI) engine were investigated. These aspects were investigated by making spectroscopic measurements of in-cylinder gas, Fourier-transform infrared spectroscopy (FTIR) analysis of intermediate products and by conducting chemical kinetic analyses. Blended fuels of dimethyl ether (DME) and methane and DME and propane were used as the test fuel. The results showed that the blended fuel of DME and methane produced two-stage primary combustion, depending on the operating conditions, which had the effect of moderating combustion. With the blended fuel of DME and propane, main combustion was occurred in single-stage.

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[in Japanese]

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Purpose of the study is to develop a thermoacoustic engine for waste heat recovery system of commercial vehicles. The most difficult point for the system is to make the engine system work at low exhaust gas temperature condition. It is clarified through simulations that a 3-stage thermoacoustic engine system is appropriate for increasing the reuse efficiency, compared to a single stage system. Further, it is also clarified that expanding the regenerator diameter increases engine system efficiency. A prototype system that is developed based on the knowledge can achieve 20% of Carnot cycle efficiency between ⊿T=150～200K.

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The internal flow in a diesel nozzle affects generation of cavitation and spray formation. The internal flow of a mini-sac type nozzle and its spray combustion have analyzed with optically visible real-size nozzle. The mechanism of cavitation formation in the nozzle hole is investigated by the study of internal flow in the nozzle sac with micro PIV method and CFD. String-type cavitation in the nozzle hole as well as film-type cavitation at the hole inlet can be observed including its generation place and frequency. The spray cone angle close to the hole outlet and spray flame are greatly influenced by string-type cavitation.

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Since the engine combustion is affected by various engine parameters as well as fuel characteristics, it is very difficult to find out the clear effect of fuel property. In order to clarify the change of emission characteristic caused by fuel change, we propose a fundamental flame research method using a small pool flame system. Characteristic of PM exhausted from a laminar diffusion flame of gasoline fuel was measured by a combustion type PM analyzer and a SMPS (Scanning Mobility Particle Sizer). Surrogate gasoline fuel and toluene (aromatic hydrocarbon) added surrogate gasoline fuel were used to clarify the effect of the aromatic hydrocarbon in the fuel. As the result, it was found that the exhaust-PM concentration increased and PM size with increasing of toluene concentration.

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Combustion and emissions characteristics of dual-component fuel were evaluated for ranges of injection timing and intake oxygen concentration. Fuels used were mixtures of a gasoline-like component, i-octane, and diesel fuel-like component, n-tridecane, so that the effects of the difference in chemistry and volatility were investigated. The experimental study performed in a CI engine and the numerical analysis using multi-component fuel model demonstrated that the dual-component fuel reduced pressure rise rate due to the difference in the vapor formation rate between two components which have the different reactivity. Furthermore, the experimental results showed that the dual-component fuel achieves low NOx and soot combustion without suffering from penalty of thermal efficiency.

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Diesel engine management systems are increasingly becoming more and more complex, large-sized and expensive to meet stringent emissions regulations. The purpose of this development is to explore the way to build a simple and low-cost engine management system while maximizing the benefits of diesel engines. In order to achieve the purpose, we blended "Power" and "Smart". "Power" is the injection system which offers extremely high pressure 250 - 300 MPa. "Smart" is the world's first closed-loop control system which automatically corrects injection characteristics using pressure signals obtained from the injector built-in pressure sensor (i-ART: intelligent Accuracy Refinement Technology). It enabled us to create all-time high added value.

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In order to improve the lubricant property of the blend fuel of JIS no.2 diesel fuel (gas oil) and 1-butanol up to that of gas oil, adding rapeseed oil methyl ester (RME) to the 1-butanol/gas oil blend was tried, and the fuel properties, diesel combustion and emission characteristics of the blend fuels with 40 mass% 1-butanol were investigated using a DI diesel engine. By adding RME to the 1-butanol/gas oil blend, the kinematic viscosity of the blend fuel increases and the smoke emission reduces due to the increase in the oxygen content of the fuel although the NOx emission slightly increases.

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This study focuses on the load analysis of ravigneaux planetary gears under operating conditions using multi body dynamics that is developed to simulate gear mesh. Analytical results revealed that the rotational friction torque of pinion and a needle roller bearing behavior generate thrust force at pinion. Experimental analysis of the thrust force was carried out by using ultra-compact data logger, and the validity of numerical results was discussed by comparing to experimental ones. Furthermore, numerical calculation was carried out, it was clarified that influence of needle roller bearing clearance and gear axial width for the thrust force.

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When we discuss the influence of battery control such as cell balance control on the performance deterioration of lithium-ion batteries, a numerical simulation model is necessary since the evaluation based on experiments requires a great deal of time and cost. In this paper, we firstly present the dynamical model of lithium-ion battery that simulates the performance deterioration for arbitrary discharge/charge patterns and battery′s thermal environment. Then we evaluate the proposed model by numerical case studies.

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Experimental study on an air-conditioning model unit was performed for improving energy efficiency of electric vehicles by use of a chemical heat pump instead of an expensive electric battery. Electric heat was chemically stored in the CaO/Ca(OH)2 reactant bed. Hot air and cold air for air-conditioning was generated under various conditions only by the stored energy.

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We previously developed a new control concept called “G-Vectoring Control (GVC)” to improve vehicle agility and stability. GVC is an automatic longitudinal acceleration control method that responds to vehicle lateral jerk caused by the driver′s steering manoeuvres. In this paper we compare GVC with the well-known DYC (Direct Yaw-moment Control) method for the daily driving range in particular. GVC shows good manoeuvrability (i.e., enhanced both yawing and lateral acceleration) performance while maintaining natural yaw and roll feeling in the early stage of cornering, while DYC is effective in improving stability during large lateral motion.

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A method was developed to estimate the wasted energy of tire by using a scalar product of force vector and velocity vector in slip region of each tire obtained by brush tire model. The method was applied to driving simulator test to quantitate the recuperative energy of G-Vectoring controlled vehicle, which accelerates or decelerates in coordination with vehicle lateral motion. It is confirmed that the wasted energy of tire was reduced dramatically by G-Vectoring control from the cornering test result of driving simulator.

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The sound-quality metrics (SQ) mapping was developed using beamforming and Near-field Acoustical Holography (NAH) for noise source identification of diesel engines. Apart from tradition metrics, such as loudness, sharpness, and roughness, a new impulsiveness algorithm was made, and the algorithm predicted the perceived impulsiveness using time-varying loudness. The performance of noise source identification using sound pressure level (SPL) mapping was compared with that of the SQ mapping both in simulations and in practical measurements. A number of monopole sound sources having a specific characteristic, e.g. loudest, sharpest, and most impulsive, were simulated. The SQ mapping was also applied to identify noise sources in two diesel engines for commercial vehicles. The current investigation revealed that the SQ mapping provided an efficient way of identifying problematic noise sources in diesel engines.

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Major factor in traffic accidents is a human error that is caused by the mental distraction. Recently, various kinds of driving support systems that prevent the human error are being developed. In this study, the effectiveness of the system to notify the driver about approaching to the intersections was evaluated in a driving simulator. For instance, the effectiveness to reduce the accidents by use of the driving support system was evaluated based on the state transition probabilistic model using the state variables such as the time until the driver notices the crossing vehicle at intersection when the driver crosses the intersection. Two types of driving support systems were compared in this study. One is with only voice guidance, and the other is tree aroma by use of the olfactory stimulus in addition to the voice guidance.

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Authors conducted macro analyses of traffic accidents/ violations in 2009 in relation to drivers′ experiences of traffic accidents/violations in 2004-2008. The results show a high probability that the same traffic accidents or violations as the ones in the past will happen. Furthermore, it is revealed that drivers who disregard traffic signals or make stop sign violations have a tendency to cause traffic accidents.

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The present study analyzed the local response of the thoracic rib-cage against blunt loading using a human elderly FE model. The model was established based on the thoracic CT imaging, representing the average anthropometry of an AM 50th percentile elderly human subject. To develop a local stiffness map of the thorax, a series of simulated frontal impact test was conducted; longitudinal impact tests with an increment of 25mm and angular impact tests with an increment of 5 degrees were done. The variation of the local stiffness and the contribution of each thoracic component to the global thoracic deflection were identified.

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This study aimed to examine the potential of using a stimulus detection task as a cognitive load assessment tool. In both experiments 1 and 2, participants drove a simulated highway route and performed some attention-demanding subsidiary tasks. Furthermore, they were required to perform a stimulus detection task in which visual, auditory, and tactile stimuli were presented in a random sequence and participants had to make key-press responses to the onset of stimuli. The reaction time and the detection error rate increased when participants performed both driving and the attention-demanding task. The pattern of results differed with the cognitive characteristics of subsidiary tasks. Moreover, the performance of the stimulus detection task was sensitive to the variation of cognitive load, which was not detected by the subjective mental workload assessment technique. Characteristics of the stimulus detection task as a cognitive load assessment tool were discussed.

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A human body finite element (FE) model with muscles of whole body was used for investigating mechanism of femur fractures in frontal impacts in fundamental study to elucidate mechanism of femur fractures caused by impacts between vehicular interior structure and knees of an occupant during frontal impacts in real-world accidents. Parametric study was performed to investigate effects of muscle tension and change in mechanical properties of bones and muscles with aging on mechanism of femur fractures.

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Various vehicles are produced according to the development of the industrial technology. The driver will take different driving postures for various vehicles. Moreover, not only the driving posture but also driver her/himself diversifies because of increases of the senior and female drivers. The combinations of the driving postures and drivers become vast number. In the future, the system that can simulate various driving posture and physical characteristics is necessary to develop the vehicle. In this paper, the integrated postural assessment system is developed using two generalized software and an original code. The original code is the motion generation model which connects the vehicle model with the musculo-skeletal model. Then an example of the integrated analysis of which motion of vehicle influence on the muscle activity is shown.

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This study clarifies influential factors and injury mechanisms in frontal pole impact crashes such as utility pole impact using Japanese accident data. The previous injury prediction model had some outlier cases of pole impact crashes because of unknown factors. A principal component analysis of frontal pole impact crashes indicates an interaction between a deformation area of vehicle and pole breakage. The injury prediction model using these factors can improve the sensitivity of injury prediction. Right-side or center small overlap pole impact crashes when the pole is not broken have higher severity than a head-on collision against a regular vehicle.

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This paper aims to clarify usability factors in In-vehicle information systems. Participants answer questionnaires about the usability of some information systems while they operate the systems during real driving. Then the analysis of covariance structures leads to principal factors.

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This study proposes a method for presenting the maneuver demand information by adding small vibration on accelerator pedal. The additional vibration is not a pure sinusoidal wave but vibration of which the change rates differ between upward and downward directions. This enables the driver to understand the direction of the maneuver he should take. In addition, the magnitude of the maneuver can be presented by the amplitude of the vibration. The effectiveness of the proposed information presentation method is examined through experiments. The results indicate that the proposed method is effective.

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Hazard anticipation relevant to pedestrians darting out to roadways is necessary to reduce the number of crashes with pedestrians in unsignalized intersections. The goal of this study is to develop an advanced driver assistance system for preventing crashes with pedestrians in unsignalized intersections by considering knowledge in hazard anticipation. This paper describes a reference longitudinal driver model with hazard anticipatory behavior based on driving data of driving license school supervisors recorded by the continuous logging drive recorder. The driver speed control model is embedded in the proposed driver assistance system and the effectiveness of the driver assistance system is verified.

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To develop a new driving assist system that can supply effective advices to help low-skilled drivers improve driving skill, we proposed a technology to extract distinctions between high- and low-skilled drivers. There are three key contributions. The first is the introduction of wavelet transform to analyze the frequency character of driving operations. The second is a feature extraction technology based on AdaBoost. The third is a simple definition for high- and low-skilled driving. Experiments were carried out using a driving simulator on a course including several curves. Results show most features appeared at the beginning and end of curves. Specially, the character that low-skilled drivers operate hesitatingly is also detected.

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Check-valves often generate severe vibration and noise around the valves. Plug vibrations, which are clearly characterized as the pendulum-like oscillations with both lateral and longitudinal vibrations, were observed through the visualization using a high-speed camera. A two-dimensional numerical simulation based on a coupled analysis of the plug motion with the fluid flow was performed to precisely analyze the phenomena. The simulated results show that the similar plug vibrations were successfully reproduced and found to be self-excited, and that the longitudinal vibration might dominantly affect the noise-generation, because the longitudinal vibration generates pulsations of flow-rate more strongly than the lateral vibration.

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The fuel consumption metrics of a plug-in hybrid electric vehicle (PHEV) is calculated by composing the energy consumption in the charge depleting and charge sustaining modes using the utility factor, where such methods of energy consumption are used as (1) the gasoline consumption only and (2) the gasoline consumption including the gasoline equivalent to electricity consumption by its heat content. In this presentation, the utility factor and the equivalent composite of electricity and gasoline are reviewed, and a representative metrics of PHEV fuel consumption to be displayed is presented.

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In the simulation of e-coating, we analyzed the paint thickness by modeling the whole car body and the paint tank accurately, and considering the car body movement in the paint tank. With this procedure we can simulate influence of the painting conditions. And in addition, it becomes possible to calculate the total amount of paint that is deposited to the entire car body.

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Recently, there are strong demands for lightweight, fuel-efficient cars. An effective joining technique to join light metals, such as aluminum and magnesium alloys, with steel is required. However, magnesium alloy and steel are especially difficult pair of metals to join. Due to not only magnesium alloy's surface oxide, but also their phase separating nature, magnesium and steel do not form an intermetallic at the joint interface. We aimed to join such magnesium alloy and steel by using Zn-Mg eutectic reaction and Al content in magnesium alloy; Zn layer was inserted between magnesium alloy and steel as plating on steel. The experiment was performed using a conventional resistance spot welding machine, and joint strength was evaluated by tensile strength tests. It was found that magnesium alloy surface oxide are removed along with eutectic melt at low temperature, and at the same time, thin and uniform intermetallic layers of Fe-Al and Al-Mg were formed at the joint interface.

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