The ignition delay times of n-C₇H₁₆ and i-C₈H₁₈ at different fuel, O₂, and N₂ concentrations were computed using a detailed chemical kinetic model generated by KUCRS. For each fuel, the dependences of ignition delay time on fuel concentration, O₂ concentration, heat capacity per unit fuel concentration, and third body concentration were separated to establish a power law equation. For n-C₇H₁₆, ignition delay time at a high initial temperature τ_High was expressed using the scaling exponents for fuel concentration, O₂ concentration, heat capacity, and third body concentration of 0.54, 0.29, – 0.38, and 0.08, respectively, and E/R of 14300 K. Low-temperature oxidation induction time τ₁ at a low initial temperature was expressed using the scaling exponents of 0.03, 0.18, – 0.17, and 0.04, respectively, and E/R of 13800 K. Ignition delay time at a middle initial temperature was expressed as τ_Mid = B(τ_High – τ₁) + τ₁.

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New improved direct fuel injector with cylinder pressure sensor has a charge amplifier installed inside the injector. The charge amplifier converts the output of the cylinder pressure sensor into a voltage. Just as before, the cylinder pressure sensor uses langatate (Lanthan gallium tantalate) single crystal as the piezoelectric element, and it is installed at the tip of the injector. This successfully reduced ignition signal noise, noise from the injector being driven, and other noise. And Torque control system using this prototype sensor is made up of a sliding mode controller and parameter identifier. The parameter identifier keeps tracking automatically, even when the target air-fuel ratio switches from stoichiometric to lean mode. Control result is good when the driving A/F is deliberately changed from stoichiometric for normal driving to lean, and the vehicle is driven in LA4 mode. Torque control data sampled at 10-msec intervals, the standard deviation is 8.2 Nm, and the deviation between engine torque and target torque remains 95% within Δ16.4 Nm.This paper presents about its performance.

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Generally, soot emission is increased in smaller-size bore diesel engine than larger one because spray-impingement on cavity wall is more significant, while keeping at constant specific output power. In the first report, it has been confirmed that soot is still increased even using smaller nozzle orifice proportional according to bore-size reduction so as to avoid excessive spray-wall impingement, compare to larger-bore engine. It has been considered that soot increase is caused by decreasing air entrainment due to shrinking of spray angle.

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In the second report, a new spray design method for smaller bore-size engine has been proposed to suppress soot emission. That theory can determine nozzle orifice size, number and injection pressure so that spray-characteristics such as specific air -entrainment and penetration are kept constant when bore size is changed. It has been confirmed experimentally that theoretical solutions based on ‘spray characteristics similarity’ can give almost constant soot emission even when bore size is reduced. It is expected that approach can reduce development process of various size diesel engine.

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The performance of heat insulation by “temperature swing” in combustion chamber walls with low-heat-conductivity and low-volumetric-heat-capacity materials were investigated with a single cylinder DI diesel engine. The heat flux measurements show that silica reinforced porous anodized aluminum (SiRPA) is one of the candidates for the materials in terms both of thermo-physical properties and reliability. The temperature swing insulation with SiRPA realizes the heat loss reduction by heat rejection and the increase in not only exhaust energy but also piston work. The temperature swing concept is demonstrated by energy balance results and the surface temperature measurement by Laser Induced Phosphorescence.

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In the former report (Second report), authors investigated the novel insulation technology by a single cylinder DI diesel engine, and showed the effectiveness of this concept. In this report, it was applied to multi cylinder diesel engines, to investigate the effectiveness in real field application. The results of single cylinder engine were confirmed in the study with the multi cylinder engine, but in higher EGR ratio condition, surface roughness of the insulation coating on piston deteriorated fuel efficiency improvement. By keeping the surface roughness of machined finish in the cavity, it was showed that the deterioration of the fuel efficiency due to the roughness was recovered.

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Porous anodized aluminum was investigated as the heat insulation material for “Temperature Swing” in combustion chamber walls. Measurement data of nano-size and micron-size porosity shows that the control of vacancy of porous anodized aluminum is mainly dependent on silicon crystallization of aluminum alloy. Porous anodized aluminum with silica coating (Silica Reinforced Porous Anodized aluminum: SiRPA) realizes the same hardness as the anodized aluminum without micro-size porosity, which prevents from breaking down in D.I. diesel engine. These controls of vacancy and reliability achieve the heat loss reduction and improvement of thermal efficiency in D.I. diesel engine.

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In order to investigate the phenomena of “Temperature Swing Heat Insulation Coat” , we developed a high response temperature measurement technique by using a phosphor. Firstly, we confirmed the sensitivity and the response of this technique are sufficient for the investigation. And then, this technique has been applied to diesel spray flame impingement section where large heat loss reduction can be expected. As a result, we could clearly measure the difference of swing phenomenon between heat insulation coat and basic metal surface for the first time.

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A thermal efficiency improvement effect by the independent control of engine effective compression ratio and expansion ratio was theoretically and experimentally confirmed in the previous paper. In this paper, the effect of further increase in the expansion ratio (geometric compression ratio, namely piston cavity volume reduction) was investigated by both numerical calculation and single cylinder heavy-duty diesel engine experiment. As a result, the potential of further thermal efficiency improvement was certainly confirmed while some issues were revealed i.e. each energy loss was increased so as not to be able to ignore it.

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A novel ignition method combining laser breakdown was developed for the realization of lean combustion. Creation of laser breakdown plasmas between electrodes prior to high-voltage application enables long-distance spark discharge. We name the method as "Laser breakdownassisted long-distance discharge ignition (LBALDI)." This method is expected to realize volumetric ignitions. This method was also tested to ignite methane/air mixture in constant volume vessel. Because the method combines the laser breakdown and the discharge, we compared laser breakdown, discharge and LBALDI. The LBALDI showed fastest heat release rate at the lean flammable limit.

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The relation between research octane number (RON) and chemical structure was investigated, and the parameters which strongly related to the auto-ignition characteristics were extracted. These parameters were applied to the HCCI combustion data and it was obvious that the ignitability trends of naphthene family were different between the RON and HCCI conditions. This might be one of the reasons why the RON can not be applied for HCCI engine test data.

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Controlled auto-ignition and mild combustion have been achieved in a gasoline compression ignition engine by two-stage fuel injection. To develop an understanding of the effect of interaction between intermediate products yielded from 1st and 2nd injections on ignition processes, simple one-dimensional modeling was performed while taking into account the detailed chemistry. Also, the effect of stratified-charge distribution due to two-stage injection on overall heat release rate was investigated by employing three-dimensional CFD and chemical reaction model. The results concluded that the intermediate products yielded from 1st injected fuel are entrained into 2nd injected spray and play an important role in enhancement of chemical reaction rather than supplying heat. It was also concluded that the amount of richer mixture should be reduced and that of leaner mixture should be increased to achieve staged mild combustion.

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In recent years, measures such as improving combustion efficiency, downsizing, installing stop-start systems, and reducing friction have been applied to engines to satisfy the requirements for reducing fuel consumption and emissions in commercial vehicles. Downsizing, for example, is effective at reducing friction loss at identical levels of engine torque. However, the cylinder pressure increases within a lower engine speed range than in conventional engines, making reliability improvements an important issue, especially around the bearings. Therefore, in this study the oil film thickness of the main bearings in multicylinder diesel engines was measured, and the data was analyzed using response surface methodology, which is a statistical analysis methods used to quantitatively derive the factors affecting oil film thickness and the extent of their contribution. Lastly, as a verification test, bearing wear on the main bearings was compared.

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Exhaust gas recirculation (EGR) is an effective method for reduction of nitrogen oxide (NOx) in diesel exhaust. However, a kind of lacquers are deposited on the EGR valve or EGR cooler because of particulate matters and other components present in diesel exhaust, which are serious problems. In this study, to investigate the mechanism of the lacquer deposition, the components in diesel exhaust have been measured using a laser-ionization time-of-flight mass spectrometry (LI-TOFMS), which allows for real-time measurements of the volatile organic hydrocarbons (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Temperature-dependent lacquers deposition was evaluated using a custom-built sample line, which had temperature slope between 323 K and 793 K, connected to the exhaust pipe of diesel engine. The components in diesel exhaust were measured where the lacquer was deposited in temperature range of 323-423 K. It was found that various kinds of VOCs and PAHs whose mass were approximately between 40 and 200 were detected and their emission trends had different from each other. It is considered that the species whose signal intensities decreased drastically in the temperature range where the lacquer was deposited probably contribute to the formation of the lacquer.

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The thermal-deterioration characteristics of the three-way catalysts for gasoline engines were investigated. According to the chemical analysis of Palladium contained catalysts which verified the aging duration and the maximum temperature, a good correlation between the mean diameter of Palladium particles in the aged catalysts and the exhaust gas purification performance was obtained. And also it was found that the degree of Palladium sintering can be determined by the thermal load. Furthermore, the authors proposed that the suppression of Palladium sintering for high-density Palladium loaded catalysts should be a critical issue.

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In the near future, some portion of diesel fuel is projected to be derived from heavy oil and be marketed. Thus, the effects of such low cetane number and high aromatics fuels were investigated on combustion and emissions in a heavy-duty diesel engine. As a result, at low load, premixed combustion was enhanced with low cetane number fuels due to increased ignition delay. By contrast, at high load, no difference was observed in combustion and emissions between the low and high cetane number fuels. Such tendencies indicate that cetane number influences combustion and emissions depending highly on in-cylinder charge temperatures.

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Hypoid gear's running performance (vibration, noise, efficiency, etc) is evaluated on a gearbox test facility. This gearbox test facility operates under the same torque and speed as for automotive drivelines. Various hypoid gears are available with different dimensions. Using the gearbox test facility hypoid gear meshing noise and vibration can be measured. Hypoid gear meshing noise is related with gearbox vibrations , gear blank vibrations and torsional vibrations of test facility driveline. The relation between hypoid gear meshing noise and transmission error, hypoid gear pinion offset and transfer torque has been studied.

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In order to reduce CO₂ emission from the commercial vehicles, the introduction of the hybrid truck into the market has been promoted. As previously reported, the fuel economy of the hybrid trucks was improved with implementation of changing the hybrid control method, but the exhaust-gas emission of it was not good performance. In this report, the hybrid control method for achieving a good balance of the fuel economy and exhaust-gas emission was investigated by using the “Hybrid Powertrain Test Bed System”. An optimum hybrid control method was to combine the method of the hybrid commercial truck at the low vehicle speed area and the method of a hybrid passenger vehicle at the high vehicle speed area. CO₂ emission produced from the virtual hybrid trucks, which adopted an optimum hybrid control method, was reduced compared to the conventional diesel truck.

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Capacity deterioration of a battery used as a power source of an electric vehicle brings about shortening of a cruising range. In this paper, we attempt to restrain the deterioration of the battery by cooling in fast charge. We discuss effect of the cooling in fast charge in terms of total cost evaluation based on a surplus cost by the battery deterioration and electricity charges for the cooling. Then we verify effectiveness of the cooling in fast charge by numerical case studies.

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Energy consumption of a HVAC system effects cruising distance of EV seriously. Therefore, saving the energy consumption of the HVAC system is a crucial problem. On the other hand, dew condensation on windshields impairs safety driving. The HVAC system introduces fresh air to prevent the dew condensation and consume energy to reheat the fresh air. In this paper, we proposed a control system that compensates a fresh air rate to prevent the dew condensation and save the energy consumption of the HVAC system.

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Fuel-cell vehicles are designed so that hydrogen leaks from the tank are stopped automatically upon detection of hydrogen leakage or detection of impact in a collision. However, to understand a possible scenario if the automatic system fails, we investigated the characteristics of hydrogen leakage sound from a hydrogen-leaking vehicle and characteristics of an alternative gas that is equal to the noise level of a hydrogen leak sound. We conducted hearing tests in an anechoic chamber to clarify how to rescue people safely in the event of a continuous hydrogen leak, depending on the sense of human hearing. As a result, we found that because of the audible characteristics of hydrogen leaks from vehicles, when approaching a hydrogen-leaking vehicle, it is best to first listen while walking around the vehicle and then approach from the maximum sound direction. In addition, a leak becomes difficult to hear when subjects are very close the vehicle. We also found that there is a linear relationship between hydrogen and helium flow rates when converting them using the noise levels in front of the vehicle. The sound pressure level of the hydrogen leaking from a pipe installed in the lower part of the vehicle and that of a helium leak are almost equal.

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For the better understanding of the pleasant handling vehicle, this paper evaluates the instantaneous static margin by using equivalent cornering stiffness which deals with the effect of non-linear tire characteristics. The yaw angular acceleration caused by the driver's sudden steering action makes steering characteristics even worse (under-steer during turn-in, and over-steer during turn-out period). By using the vertical load dependencies and longitudinal force effect, the longitudinal acceleration control and new braking /traction force distribution control between front and rear by using vehicle’s lateral jerk information are proposed for the compensation of deteriorated handling characteristics.

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This paper describes a method for reducing vibration on target subsystems of a structure composed of several steel panels by using structural intensity concept. Firstly, we deduce the modal expression of flexural vibration energy and structural intensity to discuss these relations. The numerical simulation is carried out to present that the vibration energy distribution except the components with same order corresponds to the structural intensity distribution. Next we discuss the reducing vibration on target panels of the test panel structure with line connections from the point of structural intensity. It is demonstrated that the vibration levels on the targets can be reduced by localizing the structural intensity and energy distributions with adding damping on the whole structure and the use of thicker panels.

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The rapid development of automated driving in recent years makes experiments on public roads possible. In order to realize an environmental recognition robustly, it is necessary to evaluate its performance in many situations. This paper describes an automated vehicle system for urban driving experiment. This study focuses on the behavior evaluation for lane change maneuver in highway. We propose a behavior model for lane change and a simulation platform. To do this, we record lane change maneuvers using expert drivers and evaluate their behaviors. Experimental results show the validity of the proposed system.

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The objective of this study is to understand the effects of car rotation on occupant kinematic behavior in vehicle impact with rotation. The method to provide the boundary condition for the occupants under car acceleration and rotation was formulated. Small overlap frontal crash (yawing), full-width crash (pitching) and offset impact tests (yawing and pitching) were examined by FE model simulations. The vehicle yaw motions had a small effect on the occupant kinematics. The vehicle pitch motions mitigated the loading on occupants in a frontal crash since the anchor of the seatbelt moved with vehicle pitch rotation, which increased ridedown of the occupant.

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Although engineering products have their own dimensional tolerance for the mass production, CAE (Computer Aided Engineering) simulation is normally evaluated using the nominal value for each design tolerance. However, sensitivity evaluation of the tolerance effect to the response of the product performance is important from the point of view of the robust product design and the reliability of the product. Because of the recent calculation capacity improvement using high performance computing, it becomes more and more realistic to execute a large number of the calculation such as the optimization study in CAE simulation. In this paper, we evaluate the sensitivity of the driver airbag impact simulation response by taking into account the bag dimensional tolerance and inflator production tolerance. The driver airbag's diameter dimension and vent hole diameter dimension are parameterized using morphing according to the design drawing dimensional tolerance, and inflator output performance is also parameterized according to the acceptance criterion of the production.􀀁 The global sensitivity of the each tolerance has been evaluated using driver airbag linear impact simulation using LS-DYNA model.

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High-precision and low-cost lane-level map are required from autonomous driving systems and advanced driving assistant systems. This paper proposes an automatic map synthesis method from laser point clouds that are scanned by a Mobile Mapping System (MMS). In this method, we apply a gradient image processing to detect map line segments. Results of the comparison of auto-extracted map and handmade map for the evaluation achieved over 80% extraction rate with an accuracy of 90%. We apply this system to a vehicle localization problem by matching camera images and the map and achieved sub-meter accuracy.

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The purpose of this study is reduction of the BPF noise in the engine cooling fan with generally eccentric shroud. With the increase of HV and EV, noise reduction demand has been increased. In addition, fan systems which radiator and the engine cooling fan do not have the same center is increasing. Therefore, the shroud shapes have become complicated and non-axial symmetric (eccentric). By previous report, it was suggested the solution of reduction BPF noise in the eccentric shroud by comparing the difference of sound source position and flow structure by comparing the square and eccentric shroud. This paper described the flow mechanisms of noise reduction about improved shroud by measurement of pressure and Computational Fluid Dynamics (CFD) analysis.

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An experimental study on a reduction of aerodynamic drag and an improvement of fuel economy in platoon driving was conducted to develop an Intelligent Transport System (ITS) with a good fuel economy. The study was performed to investigate the aerodynamic effect on each vehicle in 3-vehicle platooning by measuring the surface pressure on the vehicle body. The results showed that the aerodynamic drag was clearly reduced. A prediction equation to estimate the aerodynamic drag reduction of each vehicle in the platooning including the effect of a number of vehicles and each vehicle-to-vehicle distance was derived using the power law of a free turbulent axisymmetric wake. The aerodynamic drag reduction calculated by the equation agreed closely with the experimental results.

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Urea-SCR systems have been installed in heavy-duty vehicles for complying with the new long-term target-based regulation in Japan, contributing to reduce NO_x emissions. However, in fiscal 2011, a survey of Ministry of the Environment, Japan reported in-use degradation of the systems in heavy-duty urea-SCR vehicles. In fiscal 2012, in-use degradation mechanisms of a SCR catalyst and ammonia slip catalyst were reported to be hydro carbon poisoning. On the other hand, the degradation mechanism of a pre-oxidation catalyst has been a remained issue in the urea-SCR systems. We studied the in-use degradation mechanism of a pre-oxidation catalyst in urea-SCR systems and revealed temperature and sulfur conditions impacting on the degradation.

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Synchrotron ultra-small-angle X-ray scattering (USAXS) and pulsed NMR techniques were applied to investigate the vibration characteristics of carbon black filled rubber parts products such as oil seals and crankshaft pulleys. It was found that hierarchical aggregation structure of the carbon black changes by its particle size in the rubber matrix and that the aggregate of the carbon black behaves as a unit under deformation.

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Two-Stage method and MUSIC (Multiple Signal Classification) were developed for evaluating the vehicle suitability of FM devices. Nevertheless, lengthy measurement of multipath distortion rate (M_Dr) had been an issue because the maximum value (τ_Max) of delay time (τ) cannot be determined. This study has enabled to define the characteristics of M_Dr regarding modulation frequency of FM broadcast wave (f_m) and τ, and also determine τ_Max which is necessary in Two-Stage method in advance. Specifically, it was defined by measuring the characteristics ofM_Drabout f_mand τ after creating environmental characteristic models of radio waves for Two-Stage method.

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