Premixed diesel combustion is expected for the next generation vehicles, because of the high thermal efficiency and low NOx and PM emissions, but the reduction of the combustion noise, caused by the maximum rate of pressure rise, is an urgent issue for the practical use. The reduction of combustion noise by the two-stage fuel injection is a topic of this paper. With the simulations and engine experiments, the noise cancelling spike combustion was investigated and the reduction conditions of combustion noise were apparent.

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The purpose of this study was a fundamental investigation of the effects of multi-point spark ignition on a natural gas engine. Tests showed that multi-point ignition enhanced thermal efficiency through improved combustion stability. Under conditions where combustion fluctuation increased before misfire occurred, it was found that increasing the number of ignition points made it possible to extend the lean limit by increasing heat release during early stages of combustion. Under conditions where misfire occurred before combustion fluctuation increased, it was found that increasing the number of ignition points where flame propagation distance was reduced made it possible to extend the lean limit.

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Environmental regulations of the vehicle have been tightened. In order to eliminate the deviation between the actual running and testing cycle, it must reduce soot in a wide operating range of the engine than the previous regulations. In recent years, model-based calibration has become common development method. However, it was difficult to get high accuracy model because soot has strong nonlinearity. In this study, we apply the quasi-stationary measurement in order to understand the properties of the soot. We propose a method for efficiently modeling of the soot. Effectiveness of the proposed method is shown through the experimental data.

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Heavy EGR is applied for the purpose of improving the thermal efficiency, however increasing EGR incurs the aggravation of IMEP covariance due to low combustion speed. Even if large turbulence is given to increase turbulent combustion speed in a combustion chamber, this aggravation occurs in the cause of combustion instability under the further heavy EGR condition. It is important to understand this phenomenon for the enhancement of EGR and the improvement of thermal efficiency. In this paper, the factor of combustion instability under heavy EGR conditions was analyzed by using single cylinder engine test, optical engine test and 3D CFD simulation. As an analysis result by focusing combustion diagram, extremely low IMEP cycles occur when Karlovitz number becomes larger than 1.0. And the tendency of IMEP covariance depends on the amplitude of Karlovitz number.

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Ignition delay times of Japanese commercial gasoline, TRF (Toluene reference fuel; Toluene, n-heptane and iso-octane blended fuel) were measured at equivalence ratios of 0.5 and 1.0, at pressures of 2.0 and 3.0 MPa in temperature ranges of 657 - 861 K in a rapid compression machine. The simulated gasoline surrogate ignition delay times using a detailed chemical kinetic model were compared with measured ignition delay times, and the chemical kinetic mechanism for gasoline ignition were investigated. The ignition delay times of Japanese commercial gasoline increased with decreasing the equivalence ratio and decreased with increasing pressure. The ignition delay times of TRF were approximately the same as those of the commercial gasoline over the measured temperature and pressure range. While the simulated ignition delay times were slightly longer than those of the experiments, the tendency of the experimental ignition delay times was well predicted by the simulations. OH flux analysis and sensitivity analysis for ignition using the detailed chemical kinetic model of gasoline surrogate indicate that the low temperature oxidation of the n-paraffins and iso-paraffins included in gasoline are important for the Japanese commercial gasoline ignition.

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The amount of electrical energy delivered to the combustible gas is important for a successful ignition. In addition, the decreasing of the heat loss by the spark plug or cylinder wall is important for ignitability. Conventionally, the Schlieren method or ignition numerical simulation have been used for the evaluation of the ignitability. However, the directly measurement of electrical energy and heat loss has not been conducted fully in the past. In this study, a Calorimeter method is built for directly measurement of the electrical energy delivered to the combustible gas on the high pressure and high gas flow velocity conditions.

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Low emission and high efficiency is required of diesel engine. As a method of improvement of the combustion, high pressure injection is carried out. However, efficiency of atomization is very low in this method. Therefore, it is necessary to develop a technique to atomize and distribute spray under low injection pressure. Our study suggests EGR gas dissolved fuel. EGR gas dissolved fuel improves spray atomization by effervescent atomization. Furthermore, NOx emissions are reduced by internal-EGR gas. As basic research, the purpose of this paper is to evaluate the influence of the atomization characteristics of the CO2 dissolved fuel spray.

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As for reducing the lubricating oil consumption it is important to solve the mechanism of evaporation of the lubricating oil on the cylinder wall surface. This paper describes studies on the modeling of evaporation for multi-component engine oils and the relationship among the measured lubricating oil consumption, the calculated oil evaporation and the mixed oil volatility. It has been made obvious that a large portion of the evaporation results from the oil component with smaller molecular weight and higher vapor pressure. And it has been clarified how the evaporative oil consumption relates with the values estimated by Noack and TGM methods.

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It is reported that igniting rich fuel plume during or just after the completion of fuel injection period that is selected in close to TDC is effective way to reduce NOx formation by minimizing trade-offs of decrease in thermal efficiency under high load operating conditions in direct injection hydrogen engines. In this study, targeting to evaluate potentiality of improvement in thermal efficiency without considering an increase in NOx formation advanced injection timing from above mentioned was evaluated. As a result optimized elongation time from end of injection to ignition was found to improve thermal efficiency drastically. The effects were understood to be caused by increasing entrained air to the hydrogen jet plume and promote mixing of hydrogen and air. Geometry of injected plume jet which reasonably disperse fuel in combustion chamber was also found to be effective to improve thermal efficiency by reducing cooling loses to the combustion chamber wall.

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Cycle-to-cycle variations (CCVs) in internal combustion engines are caused by the combustion variations whose origin and mechanisms are not yet fully understood. The present study focuses on the CCVs of in-cylinder flows in a specially-designed motored engine that allows direct comparison between PIV measurement and CFD. Inflow conditions at the straight entrance section upstream of the intake ports are carefully measured and shown to have substantially no CCVs in pressure and velocity. Those conditions are faithfully reproduced in the present CFD using LES and RANS, where the latter is carried out to provide phase-averaged results. The PIV measurement shows the presence of CCVs of considerable magnitude in the intake stroke, which consequently leads to appreciable CCVs of swirl ratio and tumble ration even in the compression stroke. These features are successfully captured by the present LES.

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By means of a heavy duty single cylinder diesel engine equipped with multiple fuel injectors, direct control of heat release rate profile was possible through different air fuel mixture formation from that in conventional diesel engines equipped with a single fuel injector. As a result, both friction and cooling losses were reduced while keeping indicated thermal efficiency by maintaining the peak firing pressure and averaged in-cylinder temperature. Furthermore, simultaneous reduction in Smoke and NOx emissions without any deterioration in CO or THC emissions was achieved even under conventional diffusion combustion, not the low temperature combustion.

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Idling vibration of an internal combustion engine vehicle usually occurs by the engine force of 1st order of combustion. But there are other engine forces at frequencies lower than the 1st order of combustion. We call these vibrations ‘Idling vibration at low frequency range’ in this paper. THSII(Toyota Hybrid System II) drive-line has different torsional vibration characteristics compared to a conventional gasoline engine vehicle with automatic transmission. Nonlinear characteristics caused by the state of backlash of pinions and splines influences change of the torsional resonance frequency. This paper describes the control technique which can tune desirable torsional resonance frequency of this system.

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The author proposes the principal modal analysis by which the degrees of freedom can be drastically reduced, compared to conventional eigen modal analysis, while reproducing the dynamic response reasonably well.When this technique is applied to a phenomenon which has many modes, it is possible to catch a clearer mechanism than by using eigen mode analysis. Theory testing on a two degree of freedom model and case studying to a finite element model of real structure are introduced.

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This paper investigates a new shared driving system which combines Direct Yaw-Moment Control (DYC) and steering assistance system. Conventional steering assistance systems had a drawback in causing interference between the steering torque from the driver and the steering assistance systems. The proposed system can potentially solve the interference problem while achieving satisfactory course–tracking performance, as DYC is used as an independent control input. The reduction of steering assistance torque can potentially reduce the degree of the interference between the driver and the steering assist torque. Driving simulator experiment is conducted to verify the effectiveness of the proposed shared driving system by using elderly drivers.

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This study describes the reading time to contents of simple graphic display, especially traffic congestion information of ordinary roads via FM multiple broadcasting while stopping and driving. Elderly and young drivers participated in the experiment using simulated contents of the simple graphic display and a driving simulator. The reading time to the contents, vehicle behavior and subjective workload were measured based on the density of roads and the number of arrow marks indicating traffic congestion of the content during both driving and stopping condition. Based on those results, the reading time was compared and discussed between elderly and young drivers.

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Cars have utilized speech recognition and guidance for navigation systems from the early 2000s, however, the complicated mixture of multi-mode controls, such as a switch, touch panel, and speech, continues to be problematic. In this paper, we first discuss the problems with the conventional design of speech interface as equipped on a vehicle. Furthermore, to make clear the effect of equipping a spoken dialogue system, we experimentally compare the speech interface that includes natural language understanding (NLU) and spoken dialogue management (SDM) technology with the conventional speech command interface type of input. According to our evaluation, the total task and response times against LED stimuli showed significant differences for the command input type navigation system when compared with the other two speech interface types. The NLU- and NLU/SDM- type systems showed a quicker response time for each task than the command input system.

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In view of an upcoming highly automated driving, we have developed a method for maintaining driver's alertness, which does not cause discomfort and is highly acceptable. Repetitive visual stimuli synchronized with a vehicle that appears on a passing lane are presented for naturally inducing saccadic eye movements. The result of a driving simulator experiment which simulated an automated driving on an expressway showed that the proposed method could extend an alertness period of time from 20 minutes to 41 minutes.

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Crossing collisions, which are the most frequent accidents, account for 30 % of the total number of accidents. This type of collision mainly occurs on subsidiary roads at non signalized intersections. Elderly drivers tend to occur crossing collision, therefore, we conducted experiment on the test course using an experiment vehicle which was equipped with drive recorder. In this article, we report the elderly drivers’ behavior focused on the chance of velocity and drivers’ face angle at non signalized intersection and we show the risk factors that they represent.

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To support daily life in which older people can safely go out, there is a pressing need to reduce traffic accidents due to the decrease in the elderly driving ability (especially, cognitive function). This paper presents a system for detecting cognitive decline in the elderly drivers by their driving performances using a driving simulator. Furthermore, it establishes whether daily exercise habits, which are known as square-stepping exercise, have a beneficial effect on improving the elderly driving ability. The result of this past year's experiments shows that the weekly exercise for one year affects the elderly driving ability to drive safely.

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We construct a driving simulator (DS) to be used for the human-vehicle system research. It can reproduce the driving environment by immersive stereoscopic display which has five high brightness and high-definition screens. In this report, we describe the functional requirements and the effectiveness of the DS for the human-vehicle system research.

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We develop a driving simulator (DS) to be used for the human-vehicle system research. It can reproduce the driving environment by immersive stereoscopic display, which has five high brightness and high definition screens. The purpose of this work using this DS is to study the fuel consumption on follow-driving as an example of real world usage. In this report, we confirm 35% - 71% increased fuel consumption of the following vehicles to the vehicle ahead. Then we compare the driver’s operations on the point of fuel consumption. And finally we study the feasibility modification of vehicle response in order to reduce fuel consumption on follow-driving.

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To improve efficiency of heat transfer systems, techniques for reducing pressure loss of fluid flow need to be developed. Previous studies reported that pulsating flows can reduce pressure loss as compared with steady flows. However the effects for parameters in pulsating flows upon pressure loss are still unclear. In this study, the effects of Reynolds number and the Reynolds number amplitude of pulsating pipe flows on pressure loss reduction were experimentally investigated. Reynolds region for reducing pressure loss was clarified. Finally, flow characteristics in pressure-reduced pulsating flow were elucidated using two-dimensional particle image velocimetry.

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The purpose of this study is to improve the inter-laminar fracture toughness of Carbon Fiber Reinforced Thermo-Plastics (CFRTP). The plain woven carbon cloth and PA6 sheet were stacked and heat pressed to fabricate CFRTP. The needle with hemispherical tip was vibrated to axial direction by using ultra-sonic transducer. The vibrated needle was repeatedly stabbed to CFRTP toward thickness direction. The four-point bending test and double cantilever beam (DCB) test were conducted to investigate the effect of ultra-sonic needle punching on the bending characteristics and Mode I inter-laminar fracture toughness of CFRTP.

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This paper reports the development and evaluation of an automatic driving system in a local area whereby the vehicle motion is controlled by recognition and control devices on roadside and site structures. In the proposed control system, the vehicles have to be equipped with just communication devices for automatic driving, because the sensing and motion control is performed by the outer recognition and control devices. This feature reduces the vehicle cost of automatic driving, thus enhancing the social acceptance of automatic driving vehicles. In the paper the developed prototype of the proposed system and the result of questionnaire by those who experienced the system are reported.

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We developed a self-localization algorithm estimated with high accuracy and robustness. The cameras and LRFs mounted to the vehicle recognize the lane lines and the curb stones around the vehicle and the recognition results are accumulated based on the velocity and yaw rate, as a result the recognition results of wide area are produced. Self-pose is estimated by matching them to the map with the position date of the lane lines and the curb stones.

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