Center direct injection with supercharging engine is known as the method for improvement of engine output. To improve the thermal efficiency of the automotive spark-ignition engine with CNG, we applied lean combustion by using center direct injection. We tried to improve thermal efficiency by using single cylinder engine, and furthermore, we analyzed the engine data by fundamental experiment with Rapid Compression Machine (RCM) and numerical calculation. By optimization of the toroidal combustion chamber and swirl port and injection pattern and injection pressure, it was possible to optimize the air-fuel mixture distribution around spark plug. Therefore, it was possible to expand the lean limit A/F. Direct injection improved thermal efficiency compared to conventional port injection.

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This study deals with the development of controlled-ignition technology for high performance compression ignition alcohol engines. The objective of this study is quantitative evaluation of main factors that influence auto-ignition of an alcohol spray. Spray mixture formation and auto-ignition phenomena of ethanol-diethyl ether blended fuels were visualized by shadowgraph method and images were recorded with high-speed camera (8213 fps). Effects of surrounding gas pressure and oxygen concentration on ignition delay for tested fuels were investigated. The results showed that ignition delay was strongly depended on surrounding gas pressure and oxygen concentration with decreasing of diethyl ether blended ratio.

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The unburned mixture gas near the combustion chamber wall (end-gas) is compressed by the piston and the expansion of burned gas. So the process leading to the auto-ignition of the end-gas is affected by the heat release pattern of the flame during propagation. Though the spark timing is fixed, the heat release of the flame fluctuates. In other words, several heat release patterns are included under the steady state engine operation condition. In this study, how the heat release patterns of the flame affect to the auto-ignition process of the end-gas has been investigated by using zero-dimensional chemical kinetic simulations.

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Injected fuels into the exhaust line upstream of the Diesel Oxidation Catalyst (DOC), hydrocarbons are oxidized on the DOC, which increases the exhaust gas temperature at the DPF inlet as one system to regenerate the DPF. Under this system, ensuring complete evaporation and an optimum mixture distribution in the exhaust line is important. This report focuses on free spray and impingement spray to understand its physical phenomena using scattered light method, Super High Spatial Resolution Photography (SHSRP) and PIV with swirl nozzle and n-dodecane. As a result, the breakup mechanism of swirl nozzle under low injection pressure is different from Fraser's theories and break up is irregular due to the instability of the liquid film. Also it is confirmed that the follow up spray is a feature of the swirl nozzle.

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In order to predict spray feature of low-pressure swirl injector for diesel engine post treatment system, we inspected the most suitable breakup model. This report focuses on free spray to understand its physical breakup mechanism using scattered light method, Super High Spatial Resolution Photography (SHSRP) and single component fuel n-dodecane. As a result, it was clarified that the new hybrid breakup model which combines LISA (Linearized Instability Sheet Atomization) and MTAB (Modified Taylor Analogy Breakup) was effective to predict spray penetration and droplet diameter with high accuracy.

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In the diesel engine, deterioration of the degree of constant volume due to retard combustion has become a problem. Rapid combustion by shorter late combustion period is required for thermal efficiency improvement of the diesel engine. The purpose of this paper is to investigate the cause of the late combustion by focusing on mixture formation and combustion process. Therefore, visualization experiment of spray and combustion was conducted by using rapid compression and expansion machine (RCEM). And cause of the late combustion was investigated by spray shadowgraph, OH radicals, luminous flame image, in-cylinder pressure and PIV analysis data.

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The atomization structure of the fuel spray is known to be affected by flow conditions and cavitation inside the nozzle. The objective of work reported in this study is to clarify the effect of cavitation phenomena on the spray atomization. In this paper, in order to clarify the effect of magnification ratio on cavitation inside the nozzle hole and the behavior of liquid jet, the impulsive acceleration measurement and observation of flow pattern including cavitation were carried out by using enlarged acrylic nozzles. Cavitation is classified into the three patterns, and the relationship between the magnification ratio and the impulsive acceleration is clarified from this experiment.

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The characteristics of the fuel spray are known to be affected by cavitating flow inside the nozzle hole. Due to the difficulty of the investigation inside the nozzle with real size injector, there are many reports using enlarged transparent nozzle. However, the promotion mechanism of cavitation phenomena for spray atomization process has not been yet clarified. In this paper, the cavitation phenomena inside the nozzle hole was visualized by using enlarged transparent nozzles of varying length-to-width ratio (l/w ratio) in order to clarify the effect of l/w ratio on cavitation phenomena inside the nozzle hole and on the behavior of injected liquid jet. As results of these experiments, the growth and phase of cavitation depend on l/w ratio. Furthermore, it has become clear that spread of the liquid jet strongly depends on the length from cavitation reattachment point to nozzle exit.

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Optimization of piston skirt surface characteristic is effective for realizing piston friction reduction of internal combustion engine. It is important to know the effects of surface roughness of piston skirt on the friction and the oil film thickness. In this study, based on the result of friction measurement by floating liner engine, the oil film thickness is visualized and observed in a sapphire cylinder engine using laser induced fluorescence (LIF) method on the piston skirt with three kinds of surface roughness. As a result, it is found that skirt roughness affects oil film thickness and lubrication conditions.

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In direct injection gasoline engines, the spray structure has dominant effect on the ignition and combustion processes. In this study, we conducted analysis of non-evaporative spray features injected from multi hole nozzle for direct injection gasoline engine by experiment and numerical simulation using the commercial CFD code. Here, in the experiment the spray features were grasped with Super High Spatial Resolution Photography (SHSRP), which was originally developed by the author’s group. Further, it is found that the simulated spray structure such as the penetration and droplet size distribution with CFD code is well consistent with the experimental results.

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Application of low pressure cooled EGR to suppress engine knock is increasing because of advantages of engine downsizing, high compression ratio. Purpose of this study is to develop ignition system to extend EGR limit. This paper summarizes the experimental result obtained by using reinforce conventional ignition coil. The experimental results show knock suppression at high load by increasing EGR limit, EGR limit extension at these high load conditions is achieved by using reinforce conventional ignition coil. Furthermore, increased fuel economy improvement benefit using knock suppression enabled by enhanced ignition system exceeded increase of electric power consumption.

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Electric and hybrid vehicles are attractive choice due to its potential in reducing CO₂ emissions. Switched Reluctance Motor (SRM) which do not have rare-earth magnets have been considered for use as a traction motor in electric and hybrid vehicle applications. Particularly, full-pitch-winding SRMs are suitable since it has a high torque constant. However, phase current increases at high speed region because they have a high degree of mutual coupling between phases. In this paper, a novel control method to reduce mutual coupling is proposed to improve the efficiency at high speed region.

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This paper presents a real-time optimal energy management strategy with prediction of driver’s power demand for parallel HEV. By modeling a driver’s behavior and identifying the parameters of the model at each step, the power demand is predicted for several seconds in real time. Optimal energy management problem is solved by MPC using the predicted data. Simulations over various driving routes were conducted to confirm the driver’s behavior model can contribute to the better solution of the proposed optimal control problem.

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In order to archive new objective target of steering feel, model based steering feel design process is developed. The simulation model consists of full vehicle model and steering model which can describe actual friction characteristics of steering system. The target objective steering feel has been realized by applying newly defined V-shape development process to vehicle mass production development.

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It is well known that a tire lateral stiffness influences vehicle dynamics. But a lateral stiffness in service condition has not been measured until now. So tire construction designers use a lateral stiffness measured at a static condition as common sense. In this paper, a lateral stiffness in service condition (rotating at high speed) was measured with non-contact shape measurement method. In addition to it, a lateral stiffness variation corresponding to the trapezoidal slip angle input was measured. From this result, we understood that a lateral stiffness of a rotating tire can not be treated as a linear characteristic.

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The approximated minimum jerk model using the trigonometric functions is constructed from the original minimum jerk model which is high order function of time. When comparing maneuvers by the steering input of this model pattern and the original model, the model is almost equal to the original minimum jerk model. The combinations of the steering patterns are able to construct the various running courses such as the course change, the lane change and other trajectories in smooth steering. The analysis of the running data clarifies that the skilled drivers steer in this steering pattern as the basic steering input, except for the road disturbance and the sudden adjustment steering.

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In this study, driving force allocation of four drive wheels based on the tire energy efficiency was proposed. Model vehicle experiments and numerical simulations on irregular ground were carried out. In order to examine the proposed method, the results of the proposed method were compared with the other allocation methods such as even driving force allocation. As the results, it was confirmed that the proposed method improved the vehicle traveling performance and driving efficiency on the irregular ground.

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In the initial stage of vehicle development, tire characteristics that influences vehicle performance such as fuel economy, noise vibration, ride comfort, driving stability and brake performance are considered by car manufacturers. And they are requested to tire manufacturers as performance targets. To determine reasonable performance targets, it is important to estimate the tire characteristics such as mass, rolling resistance, natural frequency, vertical stiffness, cornering power and friction coefficient. In this study, the relationship between the tire characteristics and design factors has been clarified by using the L8 orthogonal array. The present method can estimate the tire characteristics.

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This paper makes clear the relation between structural intensity (SI) and acoustical intensity (AI) distributions in order to discuss the possibility of AI control by controlling SI distributions. At first the formula of bending displacement, SI and AI are summarized and the relationship among them are discussed theoretically. The numerical simulation is carried out to confirm and discuss the relationship and the controllability o f SI to AI b y using a simply supported steel panel. As a result, it is shown that the AI distribution is similar with the SI distribution under the panel with high damping. Also we discuss the characteristics of structural vibration and radiated sound under two typical SI distribution forms – vortex-typed and non-vortex-typed. And then we conclude that the SI control can control AI distribution under high damping structure, for example to control the acoustical transmitted power above the panel.

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In this study, we carried out subjective evaluation tests employing engine automatic start sounds of hybrid electric vehicle with idling reduction function. The result showed uneasiness feeling was increased by the engine automatic start sound. On the other hand, the negative feeling was actually reduced effectively by presenting a visual indicator notifying the engine start timing to the participants. The effect was equivalent to 2 dB reduction of the start sound SPL. Consequently, the rotational speed at the engine idling has a possibility to be changed more flexibility according to the electricity charging efficiency by using the visual indicator.

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This paper presents symbolization approach of large-scale driving behavioral corpus and its applicability to various ITS problems. Recently, driving data has been collected for naturalistic driving study to analyze its potential risk based on distribution of natural driving. However, large-scale driving corpus is difficult to use effectively for actual ITS applications because of its hugeness and diversity of driving situations. In this paper, a data-driven symbolization was employed for summarizing and clustering time-series driving data, and by using more than 400 hour driving corpus, we evaluated its applicability to several ITS applications; similar-scene retrieval, and driving behavior detection.

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Dirt of headlamp, such as mud or snow, reduces the front visibility of a driver. Furthermore, it has the danger to increase glare for driver of an oncoming vehicle. In this research, we investigated how the dirt of headlamp influences the glare for driver of an oncoming vehicle and the visibility on road. Furthermore, we verified about the corrective effect of the headlamp cleaner.

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We would like to develop cars that give driving pleasure to users. However, there are few reports that clarified the mechanism on the driving pleasure. In this study, a structure of driver sensibility on a winding road was clarified based on KANSEI engineering. An estimation method, that can calculate steering operations and expectations which change in process of repeatedly driving a course, was developed based on reinforcement learning. And this estimation method can calculate the relationship between driving pleasure and vehicle components characteristics.

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In recent years, smartphones have increasingly been used to offer assistance to drivers. However, safety problems may arise from certain smartphone characteristics such as their small screens and touch input systems. In this study, experiments were conducted to investigate the effect of operating an information device on drivers’ behavior while driving on a curved course. Two experiments were conducted. In one, a visual task was tested, and in the other, a verbal task was tested. The variance in the steering wheel angle was shown to track the task level.

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In the energy sources of the new generation automobiles such as a fuel cell and a clean diesel, the use of ultra-high pressure fuel more than 100 MPa is promoted. In this paper, we propose a novel leak testing technology utilizing the high pressure liquid to perform the leak inspection of the high pressure parts safely and at low cost. We fabricated the model apparatus for the liquid leak testing and examined its machine performance. As the result, the small leak rate of 10^-6 Pam³/sec was able to detect in short inspection time within 60 seconds.

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Theoretical study of a liquid leak and gaseous leak under high pressure was conducted in this paper. It is shown that the droplet fall occurs by the large leak of the liquid, and the liquid leak testing can be performed from 1.0×10^-9 Pam³/sec to 1.0 Pam³/sec at the high pressure of 100 MPa. And it is found that the leak flow rate of the liquid increases in proportion to the pressure and that of the gas increases square by the pressure. This analysis gives an index for the determination of the leak judgment value of this liquid leak testing.

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In order to speed up engine coolant warm-up, the exhaust heat recirculation system collects and reuses the heat from exhaust gases by utilizing the heat exchanger. The conventional system improves actual fuel economy at the scene of the engine restart in winter season only. The heat recirculation system becomes more effective at the low outside temperature because it takes longer time to warm up engine coolant. However, the heat recirculation system becomes less effective at the high outside temperature because it takes shorter time to warm up engine coolant. Therefore, the new exhaust heat recirculation system is developed, we adopted new devices as follows: 1) A fin-type heat exchanger in order to enhance exhaust recirculation efficiency 2) A thinner heat exchanger component and smaller amount of engine coolant capacity in the heat exchanger in order to reduce the heat mass As a result, the actual fuel economy is more improved in winter season. In addition, even at the high outside temperature seasons, the actual fuel economy is improved. Due to the change mentioned above, the weight of the heat exchanger is reduced by 20% compared to the heat exchanger in the conventional system.

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The parameters of a controller were determined by means of many iterative evaluation using a settling time and an over shoot percentage of the time response of a closed loop system. In order to provide the controller parameter efficiently, a new design method was proposed to satisfy the given settling time and overshoot using a characteristic specification of a second order time lag system. This paper investigated the application of the method to the engine speed control system. Though the target system was a relative first order time rag system, experimental results show expected performances by compensating a proper manners.

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The Extended-HILS was constructed using the original HILS which was extended and combined with the engine bench system. This system is capable of communicating in real time using the electrical signals between the vehicle model and the actual engine. And also the virtual heavy -duty hybrid vehicle in the model is controlled by the engine speed signal from the actual engine controlled by the driver model on the HILS. The Extended-HILS was evaluated with JE05 driving mode. The result showed the engine behavior was almost the same as the actual vehicle system.

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The fuel economy and emissions of the heavy duty hybrid vehicles are measured by the HILS (Hardware In the Loop Simulator) method. Following the reference vehicle speed is the first priority for the driver model of the conventional HILS. And, this driver model is not equal to the real driving behavior by the human. In this study, a new driver model which simulated the driving behavior by the human was created. The fuel economy and emissions of the heavy duty hybrid vehicles were measured by the HILS adopted a new driver model. EGR (Exhaust Gas Recirculation) system which was installed in a new engine complying with the post new long term emission was controlled in conjunction with a driver performance. Thus, the fuel economy and emissions of those vehicles were affected by the driving behavior differences.

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This paper proposes a method of cooperative driving of automated driving vehicles. In the proposed method, the vehicles share the information of their intention such as future pathway, velocity and so on, through the spatial information infrastructure by long-period (about 1s) N:1 communication. Each vehicle can decide its driving strategy considering the shred information of other vehicle’s intention, resulting in smoother flow of traffic than that realized by automated driving judging the driving strategy based on the sensor information. This paper explains the proposed cooperation method and reports the evaluation results.

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