We are studying lean combustion of natural gas engine, in order to reduce environmental load. Previously, we proposed the ultra-lean rapid two layer combustion concept, which used an engine equipped with a direct injection injector in the sub-chamber, for the purpose of improving thermal efficiency and reducing NOx. In this research, we investigated the effect of this concept on engine output, and, as a result, have increased power by improvement in combustion speed in high revolution area.

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Uncertainty of a simulated ignition event in diesel spray combustion is quantified for both RANS and LES. Sensitivities to elemental uncertainties such as the reaction rates of the surrogate fuel model, the distillation temperature, turbulent Schmidt number, turbulent Prandtl number, fitting of spray break-up models, and Smagorinsky constant in LES are analyzed. For relatively low temperature condition of 925 K, the combined uncertainty of the ignition delay time is estimated to be [-7%, 20%] for RANS while [-9%, 28%] for LES, respectively. The uncertainty budget shows that the reaction rate of progress of the surrogate fuel model most affects the simulated spray ignition event.

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Preventing cycle-by-cycle variations of combustion in gasoline engine is necessary for further improvements in thermal efficiency. In this paper, Large-Eddy Simulation (LES) of combustion in a gasoline engine was conducted with compressible fluid engine CFD code HINOCA, which is based on Cartesian grid and immersed boundary method. Prediction accuracy was verified, and influence factors of cycle-by-cycle combustion variations were analyzed with the obtained results.

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This study investigates the correlation between chemical structure and laminar flame velocity S_L of saturated hydrocarbons from methane up to octane isomers by using detailed chemical kinetics mechanisms, those were modified to reproduce the experimental S_L of alkanes and alkenes available in the literature. The mechanisms predict no dependence of main chain length on S_L except methane and ethane, and the decrease of S_L with increasing the branched structures. Reaction flow and sensitivity analysis show that the concentration of vinyl and ethyl radical have correlation with S_L because these two radicals lead to chain branching processes.

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By the invention of common rail system, thermal efficiency and environmental performance of a diesel engine have been improved. However, the present diesel engines are controlled by look-up-tables, called control maps. It requires a lot of experimental data, so it takes a lot of money and effort to make maps. Also, controller based on maps have weak robustness with respect to changes of environment. In this research, we propose a combustion controller by using feedback error learning. By using this control system, the two problems are solved. In addition, we use cerebellar model articulation controller (CMAC) as learning algorithm to reduce calculation load and learn quickly. Simulation and experimental results show the effectiveness of the proposed system.

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This paper proposes a torque correction control method for an automobile engine that reduces both dispersion in torque among the cylinders and an error between indicated value and actual value in fuel injection quantity using Unscented Kalman Filter (UKF) and a mathematical model of the piston-crank system. Moreover, the experiment results of our proposed method based on the engine test bench in steady state confirmed that proposed method is able to reduce both the dispersion in torque among the cylinders and the error in fuel injection quantity.

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In this study, exhaust gas components emitted from spark ignition engine were analyzed using a comprehensive two-dimensional gas chromatograph (GC×GC) with a time-of-flight mass spectrometer (TOFMS). n-Heptane, isooctane and cyclohexane were used as fuels. As a result of the analysis, it was found that reaction products in the exhaust gas were influenced by the molecular structure of the fuel.

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In this study, exhaust gas components emitted from spark ignition engine were analyzed using a comprehensive two-dimensional gas chromatograph (GC×GC) with a time-of-flight mass spectrometer (TOFMS). Cyclohexane, methylcyclohexane and toluene were used as fuels. As a result of the analysis, it was found that reaction products in the exhaust gas were influenced by the molecular structure of the fuel.

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By using a single cylinder optical engine with glass liner, the visualization experiments of oil behavior around the piston and rings were conducted under the condition of low engine oil temperature and low engine speed. The photochromic visualization technique proposed by the authors was applied successfully to capture the movement of oil film around the piston land and the oil flow from the gap of top ring. It was explored that the movement of oil film on the 2nd land of piston is very slow and the driving force of the movement is different with the throttle condition. The transport phenomena of oil consumption from the gap of top ring was also visualized and the importance of the oil in the groove of top ring was explored.

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In order to examine the conformability of a piston ring installed in distorted cylinder bores, a three-dimensional dynamic contacts between the ring and the bore are analyzed. The penalty method is applied for the contact problem. The piston ring is modeled by elastic solid elements, and the ring groove and the cylinder bore are assumed to be rigid bodies and modeled by contact boundary elements as rigid body. The dynamic behavior of the ring is analyzed for two different bore deformations actually measured, respectively, and the clearance area occurring between the ring and the bore is examined. The results of the analysis are compared with the ring conformability criteria shown in the previous studies. The influence of the position of the closed gap and the rotation speed of the crank are also discussed.

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Motor racing internal combustion engines are now strictly required higher thermal efficiency conscious design to compete with high performance under the regulation of fuel flow restriction. In this paper, key design parameters effectiveness to achieve the lean combustion under super high-load condition focused on the Tumble Gas motion control and the Mixture formation process.

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In recent transmissions, enhanced fuel efficiency considerations call for further weight reduction without sacrificing reliability. This extends to the comprising parts in a transmission, where lighter designs that ensure the required gear strength are expected. This paper proposes the improved predicting method relying on CAE to predict a gear tooth strain accurately considering a gear tooth contact condition. In addition, the accuracy of this method is identified by the experimental result.

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The objective of this study is to clarify the mechanism for changing the force between shafts of a chain type CVT considering the change of pitch radius of chain belt. Nonlinear decrease and nonlinear increase of the pitch radius of the chain belt were observed at the entrance and exit, respectively, due to the tilt of movable sheave. This paper found that the force between shafts was changed by the change of total of reaction forces in contraction direction, where contact arc was also changed between chain belt and pulley.

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The practical application of polymer electrolyte fuel cells (PEFCs) to the electric vehicles (FCVs) can lead to the reduction of carbon dioxide emissions and environmental friendly. Platinum-based catalyst supported on carbon is one of the important cathode catalysts for PEFCs, but the degradation of the carbon support at the high potential region should be resolved to improve the performance of PEFCs. We invented the high durable SnO₂ nanoparticles with “fused aggregate network structure” as new candidate supports to replace the carbon one. The fused aggregate network structure has some abilities to construct the electrical conducting pathways and gas diffusion pathways in the catalyst layers. The Pt supported on SnO₂ (Pt/SnO₂) showed higher oxygen reduction reaction (ORR) activity than that of commercialized Pt supported on carbon black (c-Pt/CB), especially, the Pt₇₅Co₂₅ catalysts supported on the SnO₂ showed 3 times higher ORR activity compared to c-Pt/CB. The current-voltage performance and resistivity of the cell using Pt/SnO₂ catalyst layer (I/S = 0.24) were equal to those using Pt/GCB catalyst layer (I/S = 0.67, optimized I/S ratio). The durability of Pt/SnO₂ under the load cycle and startup/shut down cycles was also confirmed to be superior to that of Pt/GCB by use of membrane electrode assembly (80oC, 80%RH). The evaluation by a low acceleration transmission electron microscopy proved that the Nafion® ionomer covered uniformly on the hydrophilic surface of the SnO₂support, though the ionomer did not on the hydrophobic surface of the Pt/GCB. The thin and uniform coverage of the Nafion® ionomer on Pt/SnO₂surface would decrease the ionomer content, mitigate the overpotential originated from the oxygen diffusion resistance in the Nafion® ionomer, and improve the cell performance.

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To improve the performance of polymer electrolyte fuel cells, we focused on the catalyst material and catalyst-layer fabrication method, and prepared low Pt loading CLs with Pt/Ta-SnO₂ by the electrospray (ES) method. The performance improvement obtained by the use of the ES method can be explained by the increase of the ionomer coverage and its uniformity on the Pt/Ta-SnO₂ due to the rapid evaporation of the solution from the extremely small size ink droplet. The performance of the ES cells is high, particularly under high gas pressure conditions, because of the improved transport of both O₂ and protons. ES method is an attractive method for the reduction of the Pt loading in the future PEFCs for automobiles.

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Inner wheel lifting phenomenon of tilting type Personal Mobility Vehicle (PMV) with active tilting system by quick steering input were investigated using front wheel steering PMV dynamic simulation model. Normalized roll dynamics dominate wheel lifting phenomenon. Large effects of roll inertia moment of sprung mass (Ixx*) and roll stiffness (Kφ) were shown. Steering input frequency ( f ) and active tilting PID control gain ( I ) also effect on wheel lifting phenomenon directly. Requirements to avoid wheel lifting phenomenon under practical use conditions were also considered.

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The automated steering control system based on the expert driver’s behavior is being developed for smooth and passenger-friendly automated driving system. In this study, a steering control model for cornering is proposed to restage the feature of acceleration change during cornering, which was observed in the driving test data by expert driver. It was confirmed by full-vehicle simulation that the developed model can control the vehicle on a single cornering course with changing the relation between acceleration and jerk and the lateral deviation from target path is less than 0.75 m, even though the vehicle speed is changed during cornering by G-Vectoring Control.

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This research deals with a construction of driver model to express driving behavior at obstacle avoidance. A risk potential model is constructed with a control algorithm including a target course determination process. The steering angle of feedforward control is calculated using curvature of risk minimum point at the risk potential map corresponding to the target course. On the other hand, the steering angle of feedback control is calculated using the difference between left- and right-hand sides of the risk potential at prediction point. As a result, the risk potential model can describe the driver behavior when obstacle avoidance.

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This study examines lane-keeping performance of motorcycles using steering control system designed by the Model Matching Control (MMC) to improve transient characteristics. The effects of the MMC on the lane-keeping performance are evaluated by examining computer simulation with the rider-in-the-loop system which consists of a motorcycle model, a steering control system and a rider control model. The MMC realizes the good lane-keeping performance under the steering torque disturbance in comparison with the conventional control without considering transient characteristics by improving the tracking performance of the actual rolling angle to the commanded rolling angle.

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In this study, a subjective evaluation test about uncomfortable feeling was carried out. Vehicle interior noise and steering vibration having various levels were presented in a sound chamber through headphones and dummy steering wheel. As the result, the interior noise had larger influence on the uncomfortableness than the steering vibration in a group. On the contrary, the vibration had larger influence than the interior noise in the other group. In addition, this characteristic was clarified to depend on the participants' point of subjective equality between the interior noise and the steering vibration.

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Various ride comfort control methods using suspension control devices have been proposed. This paper describes research into a simple control law that uses only sprung acceleration sensors to effectively reduce disturbance inputs over a wide frequency range by applying skyhook control to the sprung mass using three elements instead of just the dampers: the dampers, springs, and inerters. Reflecting the number of elements, this control is called the triple skyhook control.

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In this study, we used robot which was the most acceptable among ´voice´, ´vision´ and ´robot´ as a driver-agent. We verified whether the driving behavior improvement by driving the driving simulator together with the agent. The agent's support was 3 kinds of "driving-support", "feedback" and "driving support and feedback". Driving-support was real-time support by robot's voice. Feedback looked back on unsafe driving behaviors with movie after driving. Driving-support and feedback was combined use of both. As a result, driving behavior was improvement by using an agent. Driving behavior was the most improved condition was "driving-support and feedback". And, the condition with higher subjective evaluation was "driving-support and feedback".

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Regarding serious accidents caused by reversed vehicles, mistakes in pedal stepping are focused, but in reality lot of them occur during normal driving behavior. This presentation focuses on the backover accidents that the weak vulnerable road users (VRU) were killed or seriously injured and consider characteristics of those accidents using domestic accident traffic statistics and in-depth investigation cases, and special crash investigation data in US.

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Thermal management: engine cooling and heat protection, by CFD is an important part of vehicle development process. However, as the heat transfer phenomena in the underfloor and engine room of a vehicle are very complex, it is difficult to predict accurately the temperature variations of vehicle parts under an unsteady driving mode. To improve the prediction accuracy, we optimized the cooling fan model and the radiative emissivity of parts. As a result, the peak temperature error between prediction and testing is less than 15 K in the key off stage.

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Unsteady wake structures around a bluff body, which has a slanted rear surface, is investigated experimentally with measuring the velocity and the pressure fields. Velocity distribution obtained by a Particle Image Velocimetry showed that vortices are intermittently generated and occasionally it grows to large-scale vortex which separates the flow from the slanted surface. From the pressure distribution, which is simultaneously measured with the velocity field, it is clarified that the large-scale separated vortex has considerable extent in the spanwise direction. This fact suggests that the re-attachment line of the downwash is completely separated from the slanted surface when the largescale vortex is generated. From the time-frequency analysis, which is applied to the velocity fluctuation measured by hot-wires, the flow observed at downstream of the body exhibits the periodic fluctuation, whereas the flow near the slanted surface does not involve the periodic fluctuations. Instead, the intermittent fluctuation is observed for the case that the downwash of the flow structure is separated from and re-attaches to the slanted surface. The intermittent fluctuation on the slanted surface is observed regardless of the existence of upwash, whereas the periodic fluctuation at the downstream vanished when the upwash is absent.

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The fatigue properties of arc welded lap joints using joggle-shaped 980MPa-grade steel sheets were studied in a plane bending fatigue test. The fatigue strength of the joggled lap joints was superior to that of the conventional lap joints. The influences of joint geometry, residual stress, and hardness near the welds on the fatigue strength of the joints were investigated. It was found that the average values of flank angles and curvature radii at the weld toe of the joggled lap joints were greater than those of the conventional lap joints. Furthermore, histograms of flank angle and curvature radius indicated that the joggled lap joints had lower probability of crack initiation than that of the conventional lap joints in the low load stress region. Therefore, the fatigue strength of the joggled lap joints were considered to be improved.

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In order to clear diffusion characteristic of tail pipe emission such as PM, its behavior behind a truck body was investigated using a model of 1/32 scale medium duty van type truck and a wind tunnel with moving floor. As for a modeled tail pipe exhausting emissions such as PM, THC and CO₂, CO₂ was used because CO₂ was main composition of exhaust gas, and turbulent diffusion behaviors of PM and gaseous emissions in the exhaust were considered as same. CO₂ was exhausted from the tail pipe to a downstream air flow around the truck and its spatial distribution behind the truck was measured. As the results, exhausted CO₂ was rolled up by the recirculation air flow behind the truck model when CO₂ exhausting gas velocity was less than the main flow velocity around the truck. However, almost of exhausted CO₂ did not roll up when CO₂ exhausting gas velocity was higher than the main flow velocity.

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Driving cycle test procedure for automotive fuel economy and emissions can analyze limited condition in real world driving. A gap between fuel economy on certified test and real world test become larger recently. This paper proposes an alternative method of driving cycle test procedure for automotive fuel economy index using VSP which defined on MOVES and verified an advantage of the method applying to various powertrains on virtual test driving. As a result, it was reported the method is useful to estimate a fuel economy for various type of use, creating a fuel economy characteristics with the vehicles. Furthermore, modified method is required for estimating a hybrid powertrain models and confirmed the accuracy of estimations by the modified method.

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Precipitation hardening stainless steels is difficult to deform them by cold forging process because of the high hardness and low elongation. This report is a fundamental study of cold forging in precipitation hardening stainless steels. In the present study, the forward extrusion followed by backward extrusion was conducted in order to confirm the possibility of consecutive plural cold forging process. By the optimization of the dies configuration and shape with simulation prediction, the target forming with rectangular depression over cylindrical depression and rectangular projection on opposite side could be obtained. The microstructure and work hardening behavior were estimated by grain flow visualization and hardness distribution.

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The vibration characteristics of long fiber CFRP (Carbon Fiber Reinforced Plastic) specimens with the same dimensions are different when the specimens are manufactured using different SMC sheet layout for compression molding. Therefore, we propose a new vibration analysis method using the orientation and stiffness of long fiber tow. The orientation of the fiber tow is obtained from the compression molding analysis, and the stiffness of the fiber tow is calculated using FE (Finite Element) model based on X-ray CT (Computed Tomography) image. The analysis results of this new method correlated well to experimental results of the specimens.

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The variation in fuel economy and emissions at the real vehicle driving is influenced by the human driving behavior. In this study, we focused to decrease these variations. The real vehicle driving performance is evaluated by using the chassis dynamometer and the driving-robot. Driver model in this robot was reproduced the intelligent driver behavior. And, this driver model was not necessary to get the powertrain performance (accelerator map) and to adjust any parameters, which operated the driving-robot. We evaluated the driving performance by using the driving index, which will be adopted by WLTP (defined in SAE J2951). The driving-robot with this model was equal the driving performance by human at cold and hot start. So, by using this driving-robot, we can maintain the equity and efficiency at chassis dynamometer test.

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