Diesel engines have a high thermal efficiency, but 20-30% of the input heat quantity is lost as the cooling loss. It is important to investigate the mechanism of wall heat transfer with flame impinging on the wall in improving the thermal efficiency. Therefore, in order to investigate the correlation of diesel flame and the wall heat loss, chemiluminescence photography, luminous flame photography and measurement of heat flux were carried out by using a wall insertion type constant volume vessel.

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Research on natural gas lean-burn engines is being performed to reduce the environmental impact of the internal combustion engine. This study proposed a two-layer ultra-lean rapid combustion concept that uses an engine with a sub-chamber equipped with a direct-injection injector to achieve both thermal efficiency enhancement and NOx reduction. The feasibility of the concept was investigated using a single-cylinder engine, and the engine data was verified by means of numerical simulation and fundamental combustion experiments using a constant volume chamber.

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Research on natural gas lean-burn engines is being performed to reduce the environmental impact of the internal combustion engine. This study proposed a ultra-lean rapid two-layer distribution combustion concept that uses an engine with a sub-chamber equipped with a direct-injection injector to achieve both thermal efficiency enhancement and NOx reduction. The effects of the sub-chamber specifications on combustion were investigated by single-cylinder engine tests and constant volume chamber combustion tests. Consequently, we confirmed the effects of the sub-chamber specifications on engine performance and grasped the behavior of burned gas jet from sub-chamber.

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In order to understand the mechanism of lubricating oil consumption (LOC) and the details of it, nowadays cylinder visualization method which can observe direct oil motion in a cylinder and analyze oil film thickness by the image analysis is used. In this study, more detailed oil transportation by the simultaneous measurement of the visualization, ring motion and the pressure of piston lands in decelerating condition is reported. Oil transportation depends on the level of inertia force and vacuum pressure influenced by the ring axial motion.

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The overall deposit generating mechanism has been considered by detailed chemical analysis of deposit produced in a wide temperature range and condensed water. Deposits that have different properties were generated according to the temperature range. Deposit generating mechanism is condensation and solidification and polymerization reaction of hydrocarbons (HC), and these contributions will change. Deposit generated in the low temperature range is soft at a room temperature, which suggested that condensation of low-boiling HC components was main factor for the deposit generation. On the other hand, deposit generated in the high temperature range is hard and lacquer-like material. Main factor for the hard deposit generation mechanism was condensation of high-boiling HC components and polymerization reaction. In addition, even if the deposit was soft at the room temperature, it becomes hard and lacquer-like material due to the effects of subsequent temperature history.

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With the conflicting goals of achieving both a high purification level and low pressure loss, an attempt was made to control the flow velocity distribution by means of a new honeycomb structure (a compound cell structure having an inside area with a higher cell density and an outside area with a lower cell density). The catalyst utilization efficiency was maximized by optimizing the cell specifications of the inside and outside areas, and their effects under an actual usage environment were compared with conventional substrates, using actual vehicles and engines, and reported in this paper.

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In this study, using multi-diameter particle model, we simulated the flow and soot deposition in DPF. Structure of SiC-DPF was obtained by an X-ray CT technique. We discussed the soot deposition process by changing the soot diameter, and evaluated the pressure drop across the filter (filter backpressure). Especially, we focused on the soot deposition region which could affect the pressure drop. Also, the soot cake permeability and the soot packing density were investigated. As the soot diameter is smaller, the soot cake permeability increases and the soot density decreases. When the soot diameter is smaller, the soot cake is thicker. Hence, the enlarged pressure drop is explained by the fact that the smaller soot is easily trapped on the filter surface due to the Brownian diffusion.

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In the three-way catalysts (TWCs), the ability to reduce exhaust-gas emissions is insufficient to cope with real driving conditions such as low temperature below 0°C. To improve the activity of TWCs, our study focused on the exhaust-gas purification performance and the sintering characteristics of platinum-group metal (PGM: palladium, rhodium, and platinum) particles aged at 1000°C. From our extensive analysis of mass-production catalysts covering a wide range of PGM loading amount, it was clarified that the catalysts with enlarged PGM particles after severe aging had higher turnover number than fresh catalysts. Moreover, the purification performance was affected significantly by PGM loading amount. Especially, rhodium catalysts having loading amount more than 4.0 g/L showed high catalytic performance.

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Gasoline surrogate mixtures consisting of five components, isooctane (branched-chain alkane), n-heptane (straight-chain alkane), methylcyclohexane (cyclic alkane), toluene (aromatic), and diisobutylene (alkene), were proposed and a corresponding detailed chemical kinetic model for combustion, SIP-Gd1.0 (SIP gasoline surrogate detailed kinetic model revision 1.0), has been constructed. The mechanism well reproduces the ignition delay times measured by shock tubes and laminar premixed flame propagation velocities of air-mixtures of each component, two and three components mixtures (PRF and TRF), and five-component surrogate mixtures corresponding to JIS 2nd grade gasoline ("regular") S5R and 1st grade gasoline ("high-octane") S5H.

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Conventional calculation methods with a 2 zone combustion model for gasoline engines needed a heat release pattern obtained by experiments. The way of calculation for obtaining turbulence intensity in a cylinder using intake velocity was proposed, and the turbulent combustion speed came to be estimated using the turbulence intensity. But any reliable calculation method has not been established. A calculation model considering a vortex scale in the combustion zone is proposed, and it is confirmed that the accuracy of the model is better than conventional ones. The calculation model and its advantages are described in this paper.

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By installing the oxygen sensor on the engine air intake side, an advanced EGR control becomes possible and fuel efficiency improvement can be expected. On the other hand, if the fuel vapor reaches the sensor element of zirconia-based solid electrolyte, the fuel vapor can ignite because the element is heated. The risk, however, is slight. Therefore, we evaluated the explosion-proofness of the protection tube by numerical simulation method we developed, and it was confirmed that the dimension between the inner and outer protection tubes has a great contribution.

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In this study, we calculated cylinder deformation under high pressure condition. Proposed model treated contact interaction between a head gasket and a cylinder block deck surface or a cylinder head considering frictional and shear behavior of the cylinder head gasket. The model was able to predict the changing margin of the deformation by different gasket structure type. According to the results, we found that transient phenomenon was occurred by changing contact interaction state from stick condition to slip condition regarding cylinder deformation toward cylinder pressure. Besides, we found that head gasket shear stiffness and frictional coefficient affected cylinder bore deformation.

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In order to investigate the surging phenomenon that occurs in a turbocharged engine, unsteady pressure distributions at several positions in a compressor of an automobile turbocharger were measured using semiconductor pressure sensors. Furthermore, the reverse flow at the inlet of the compressor was visualized by the tuft method. The experimental data were then compared with the results of numerical simulations of the internal flow at the conditions of lower mass flow rates near the surging range in order to clarify the generation process of the reverse flow.

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A two-zone combustion model, in which cylinder volume was separated into combustion and non-combustion zone to simulate general diesel combustion phenomena, was developed to investigate the current status of inhomogeneous (diesel) combustion compared with ideal homogeneous combustion from the instantaneous specific heat ratio variation and corresponding indicated thermal efficiency view point. The computed results were compared with experimental results by means of a single-cylinder engine, and suggested the potential of further thermal efficiency improvement by further diluting and homogenizing the combustion zone, particularly during isobaric combustion phase.

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For improvement of fuel consumption and the exhaust gas emission of automotive engines, the measurement of combustion conditions in the engine on the real vehicle tests are important as well as the engine test on the bench. In this study, we developed a portable combustion monitor system that can measure indicated mean effective pressure (IMEP) from plug washer type force sensor and ECU crank signal. As the result, we verified that IMEP can be measured with untoothed pulse and found a good correlation between equivalent IMEP from plug washer type force sensor and IMEP from ordinary pressure diagram.

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With the recent demand for improvement of fuel efficiency in cars, friction reduction between timing chain and its guide is strongly required. To optimize the chain shapes and dimensions for the demand, understanding of friction mechanism between the link plate of chain and guide is necessary. From these backgrounds, oil film thickness formed between the link plate of timing chain and its guide was measured by means of optical interferometry in this study. In addition, the friction force under sliding condition was also measured, and the relationship between the oil film thickness and friction force was finally discussed.

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In this paper, it was discussed theoretically about the function of a planetary gear inerter from the view point of the difference from ideal inerter. According to the formulation of function of a planetary gear inerter based on velocity diagram analysis, it is proved that a planetary gear inerter has the function of redistributing moment of inertia comparing with an ideal inerter. This function affects to the frequency characteristics of the torsional vibration system. As a result, a planetary gear inerter is feasible to expand the design flexibility of frequency characteristics of the torsional vibration system.

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It is important to develop the hybrid vehicle drive motor without heavy-rare-earth. It is because demand expansion of hybrid vehicle and procurement risk of heavy-rare-earth. We developed the Hybrid Vehicle drive motor without the use of heavy-rare-earth elements. In the development, we studied rotor shape for low coercive force, especially shape of center rib, flux barrier shape and small hole in order to enable to use developed heavy-rare-earth-free magnet.

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In order to reduce the emissions of the heavy-duty diesel plug-in hybrid vehicles (PHEV), it is necessary to provide the high exhaust-gas temperature and to keep the aftertreatment system effective. The engine starting condition of PHEV is cold, and the engine start and stop is repeated. Therefore, the warm-up of the exhaust-gas aftertreatment system for PHEV takes longer time. So, it may cause negative effects on the emission characteristics of PHEV. In this study, we focused on the electrically heated catalyst system (EHC), which is one of the next generation electrical technologies. This test PHEV was equipped with EHC. The fuel economy and emission characteristics of this test PHEV were estimated using the extended-HILS. This result was that NOx and CO₂ emission of this test PHEV which was equipped with EHC was good, compared with the heavy-duty diesel vehicle, the heavy-duty diesel hybrid vehicle and conventional PHEV which was not equipped with EHC.

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Hydrogen starvation detection is one of key technologies to prevent fuel cell degradation, and electrochemical impedance spectroscopy (EIS) is powerful tool for it. In general, EIS can measure average electrochemical state inside a stack, and measured impedance is easily affected by electrochemical reaction distribution. So, it is necessary to understand relationship between measured impedance and reaction distribution in order to detect local hydrogen starvation caused by complex transport phenomena. For this purpose, real time impedance measurement was conducted by using a short stack with segmented cell. The results suggested developed impedance system had future possibility to detect local fuel starvation.

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Miniaturization of automotive electronic components is required in order to improve the comfort of the vehicle. For this, reduced size and increased density of the printed circuit board becomes indispensable, but issues then arise with insulation degradation due to ionic migration. In this paper we describe the results of our observations of ionic migration due to differences in materials in the circuit board and resistor and the electric field pattern.

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„Moment Plus(M+)“ is the yaw-moment control based on lateral jerk information, and the effect of M+ on lane change maneuver was studied from driver’s controllability point of view by driving tests. The driving tests were performed on dry asphalt and packed snow road condition with several drivers. It was confirmed that M+ can improve the success rate of lane change task even though the effect on the steering maneuver depends on the driver.

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This study discusses steering control for motorcycles using Model Matching Control (MMC) to improve transient characteristics. By examining computer simulation with a simple motorcycle model, the MMC performs the desired rolling angle generated by the steering torque of the feed-forward control. Increasing natural frequency of the reference model improves the tracking performance of the rolling angle, and increasing damping ratio stabilizes the response. The MMC shortens the rise time of the rolling angle in comparison with the conventional control without considering transient characteristics. The MMC also performs the robustness to the parameter uncertainty.

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The significant problem for active safety system and ADAS (Advanced Driving Assistance System) is how to recognize driver behavior such as where driver look in a scene or what driver aware of their environment. In order to recognize the driver behavior, it is necessary to estimate gaze direction and gaze region in forward environments. In this paper, we propose a method that estimate gaze direction and extract driver’s gaze region in forward image using estimated head pose from in-vehicle cameras.

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In recent years, actual operation of truck platoon system in mixed traffic is considered under the limited traffic environment such as the expressway. As a truck forms a platoon with short gap in this system, the truck platoon may adversely affect a general traffic. Therefore, in this study, general drivers' acceptability to the spec of truck platoon is evaluated by experiments using driving simulator.

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The interaction between human and vehicle has been researched to reduce the traffic accident in Japan. In the research of driver assistance system, more driver friendly assistance system has been researched using the information of driver and vehicle. This system requires to achieve a better relationship between human and vehicle. In addition, it is important to find a method to determine a driver's operational intention. Therefore, we have focused on the brain activities in the biological information. The time frequency analysis such as FFT has been major method in the traditional decomposition of the electroencephalogram (EEG). However, these conventional methods can only use two-dimensional data. In our previous research, we investigated that the driver’s EEG at the preceding car avoidance maneuver was decomposed by parallel factor analysis (PARAFAC), and we investigated the feature factor of longitudinal behavior for recognize and judgment from that decomposition result. PARAFAC analysis has known as a multi-channel EEG analysis of multi-dimensional data. In the previous research, we investigated the driver’s EEG of during longitudinal operation using PARAFAC. Consequently, all subjects have two common factors of the frequency component which exist in the 5-10 Hz and 8-13 Hz region. Those factors were changed by the driver’s mental state during visual recognition and judgment. In this paper, we estimated the driver’s intention from a driver’s EEG using source current distribution estimation with Hierarchical Bayesian method and the sparse logistic regression. From the estimation results, the estimation accuracy of driver’s intention was higher than about 70 % of two subjects’ in the longitudinal operation.

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To investigate the impacts of aging of the retina on visual perception during driving, we simulated retinal responses to traffic scene movies using a large-scale neuronal network model of the aged retina. The model was able to simulate retinal responses within a visual field of 30 deg in diameter. Aging in the retina was characterized by reduced number of retinal cells. Simulation results indicated that necessary information for traffic scene understanding was, at least partially, degraded in the aged retina. Our findings suggest that elderly drivers receive restricted visual information for traffic scene understanding due to age-related decline in retinal function.

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This paper uses a psychological experiment conducted on a human-tool-system from the viewpoint of sense of self-agency as an example to describe the phenomenon that matching temporal variation between human operations and the control subject gives the impression that the tool is under the operator’s control. This knowledge was used to evaluate an actual driver-vehicle-system during acceleration from standstill, and this application was verified. The results suggested that the degree to which the time-series waveforms match between accelerator pedal operations and vehicle speed influences the creation of a feeling of embodiment with the vehicle.

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In order to advance multi-materialization of automotive body structure, we developed a new dissimilar metal joining method of steel and aluminum alloy sheet named Dimple Spot Welding (DSW). DSW has a laminated structure of Fe-Al-Fe, and is a welding method of dimple and backing plate. As a result of tensile shear tests and cross tensile tests using steel and aluminum specimens joined by DSW, the following results were found out: 1) Joining strength of DSW depends on combination of dimple height of steel sheet, and hole diameter of aluminum alloy sheet. 2) Bonding strength of DSW was equal to or higher than that of conventional mechanical joining methods such as SPR, FDS^®, Clinching, and so on.

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