Laser-clad valve seats directly deposit wear-resistant alloy onto cylinder head. This direct deposition process enhances knocking resistance by raising thermal conductivity, and improves combustion efficiency by increasing design flexibility around the ports. This technology enables innovative cylinder head design that helps to improve the trade-off relationship between tumble flow and intake resistance. As a result, it helps greatly increase engine thermal efficiency and specific power. To enable the application of this technology as a global, a new wear-resistant material was designed for use with alternative fuels. in addition, a new energy-saving manufacturing process for worldwide production was developed.

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In order to reduce the heat loss, it is necessary to grasp the correlation of each physical factor and the experimental parameters such as the injection conditions and nozzle specifications. The correlation was examined in previous report by using the wall insertion type constant volume combustion vessel that can simulate the wall collision of the spray flame in diesel ambient field of high temperature and high pressure. In this report, the effects of mixed fuel on thermal efficiency and exhaust characteristics are examined by using 4 cycle single cylinder diesel engine in the high load operation(Engine speed:2250rpm, IMEPg:1440kPa), and its combustion mechanism is investigated by using RCEM(Rapid Compression and Expansion Machine).

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In this research, we investigate the heat transfer mechanism with visualized Rapid Compression and Expansion Machine. Therefore, we measured the heat flux in the diesel combustion field with coaxial type thermocouple. In this report, we aimed to investigate effects on changing of fuel property on the heat loss by wall heat transfer with dual component fuel (Pentane and Decane). Dual component fuel (P_inj = 180 MPa) is compared to diesel oil (P_inj = 180 MPa) ,the cooling loss decreased by 13.1% by activation of combustion in the cavity at the late combustion period (at 1.0 to 2.0 deg.ATDC) and realization of low penetrating power spray flame.

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For the improvement of transient driving performance of diesel engine, it is effective to control the fuel injection timing and quantity using model-based control (MBC) on ECU (on-board) with cycle-by-cycle calculation. The authors previously developed an on-board in-cylinder gas flow model and wall heat transfer prediction model those are a part of models for MBC. This study measured in-cylinder gas flow velocity using the PIV measurement and the CFD analysis to obtain the turbulence intensity coefficients of in-cylinder gas flow expressed by the ratio between mainstream velocity and fluctuating vertical velocity towards in-cylinder wall. As a result, it was found that the turbulence intensity coefficients at intake and compression strokes obtained by the PIV measurement were 0.014 and 0.018, respectively, which were smaller than the coefficient of 0.041 from the CFD results. Compared with the heat flux measurements, the prediction errors of wall heat fluxes using the CFD’s and the PIV’s coefficients were evaluated to be 45.0% and 0.28%, respectively. These suggest the necessary to improve the determination of turbulence intensity coefficient.

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The mechanism about in-cylinder phenomena which is the main source of Particulate Matter (PM) emission under low temperature transient conditions before warm-up is analyzed in this study. As a result, a key parameter of the Particulate Number (PN) reduction under low temperature transient conditions is clarified. It can be stated that larger cycle to cycle carryover fuel film on the combustion chamber wall makes higher PN that is clarified in PN evaluation including transient condition. For PN reduction, cycle to cycle carryover fuel film should be considered. Therefore carryover fuel prediction tool has been constructed. And then, counter measures are found from those clarified phenomena.

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This study deals with the development of controlled-ignition technology for high performance compression ignition alcohol engine. The objective of this study is to make clear the effect of hot EGR on ignition, combustion characteristics and thermal efficiency of alcohol fuels in a small DI diesel engine with high compression ratio. Ignition and combustion characteristics of four kinds of alcohol fuels (Ethanol, Propanol, Butanol and Pentanol) were experimentally investigated. Experiments were carried out within the range of 1200 rpm to 1600 rpm in engine operating speed with changing hot EGR ratio under high compression ratio (ε=23).

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Effects of spray characteristics in non-reacting condition on ignition delay and flame in reacting condition were investigated. Three spray models were employed, which are fit to the result of non-reacting experiment in different ways. Ignition delay in reacting condition is affected little by vapor penetration and spray angle in non-reacting condition. Flame lift-off length and flame tip position in reacting condition are strongly affected by initial vapor penetration in non-reacting condition and not affected by vapor penetration at corresponding time in non-reacting condition. Therefore, initial part of vapor penetration is more important than the other part in spray modeling.

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The mechanism of engine oil consumption due to the scraping action of the piston ring pack was investigated through experimental measurement and numerical prediction of the scraped oil amount. Since the measured amount of scraped oil was inconsistent with predictions using commercial software, a novel theoretical model of the oil film retraction phenomenon was constructed based on experimental observations when the ring descends. This model was then applied to the ring lubrication calculation. The model predicted that the barrel height of the ring sliding surface profile strongly affects whether the retracted oil film grows, which is consistent with the experimental results.

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A simulation model is useful to evaluate the NOx emission in real-driving due to variable conditions such as, environmental and traffic conditions. In the authors’ previous study, it was possible to predict the NOx emission in real-driving conditions using a vehicle without a NOx reduction catalyst. In this study, a new model to simulate the amount of NOx emission was developed and evaluated under different engine specifications using a vehicle equipped with a NOx reduction catalyst. An introduction of a coefficient of NOx conversion efficiency enabled the quantitative prediction of NOx emission at tail-out by accounting for the temporal variation of catalyst’s temperature.

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The Laser Absorption Scattering(LAS) technique is used to investigate the fuel mixture formation process．This method is able to measure the liquid and vapor phase concentration distribution in the diesel spray．The conventional LAS method which adapts on Nd:YAG laser with the 266 and 532nm wavelength has a limitation that，only one image of the spray in one injection event can be captured at a given timing．This method requires many different injection events in order to acquire a set of sequential images．To solve this limitation，a continuous laser (532nm) and pulsed LED (266nm) were used as the light sources for the high-speed LAS imaging．To capture the time-resolved image，two high speed video camera were used．One high speed camera detected the 532nm light while the other was coupled with the image intensifier to detect the 266nm light．In addition to that，the results are compared with conventional single shot LAS results．

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The methods to stabilize the measurements of the soot mass concentration and particulate number and size distribution of particulate matter produced from the combustion chamber in engine experiments were examined with a single cylinder direct injection engine, as well as obtaining the basic data for the construction of particulate matter generation model of SIDI (spark ignition direct injection) gasoline engine. Compared with a direct measurement close to the exhaust ports without any pretreatment, by significantly reducing the pressure pulsations at the inlets of soot meter and particle counter, the results with better stability and reproducibility could be obtained with measuring the soot mass concentration at the downstream of a surge tank equipped in the exhaust pipe, and particulate number and size distribution with the presence of the chamber in the sampling line at the upstream of the diluter even under different conditions of particulate matter emission behavior.

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Though it is necessary to evaluate the emission emitted by vehicles in a real world to grasp local vehicle emission pollution, it is impossible to measure the real world emission for all vehicles. In the previous report, the formula for calculating NOx emissions based on the results of engine test and vehicle test was proposed. In this report, we report on the result of constructing a vehicle model and driver model that is necessary for realizing the driver’s behaviors and vehicle behaviors during real world driving.

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The first and second reports proposed a new heat transfer coefficient formula that is applicable to diesel combustion. This, the third report, incorporates the results of the previous two reports into the heat loss prediction algorithm and evaluates the prediction accuracy over the whole engine operation range. As a result, it was clarified that prediction accuracy of heat loss improved over the whole engine operation range, and it was possible to predict indicated mean effective pressure with an accuracy that mean absolute error was less than 2.3%.

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In these days, improving fuel economy of SI engine is required in the world due to energy securities and environmental issues such as climate change. Engine thermal efficiency is affected by knocking whose occurrence timing is governed by the ignition characteristics of the air fuel mixture. In this study, relationship between the fuel chemical reaction characteristics, knocking indicator such as octane numbers and the engine operating condition is clarified. And the knocking indicator p-T map is clarified with comparison of engine experiment.

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For lean burn in gasoline engines, combustion in high flow field is demanded and steady spark ignition in high velocity flow is required in advanced ignition. The flow field stretches discharge channel in the ignition phase and it affects the voltage and current profile. From this background, experimental studies were conducted focusing on the discharge channels stretched by the flow. The small wind tunnel which controls the flow velocity using orifices is used for experiments. Electric current and voltages were measured and its characteristics were discussed. The discharge channels are observed by high speed camera and the length of discharge channel was estimated. Using electric current and voltages, line resistance was estimated and was shown as the function of the electric current. The relationship between the line resistance and electric current was compared with the previous works.

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In the diesel engine, pre-injection carried out just before the main injection was effective in combustion noise reduction. On the other hand, the pre-injection spray can affect the smoke emission through the interaction with the main injection spray. Therefore, the spray to spray interaction and smoke emission were analyzed by simultaneous visualizing of the spray drops and smoke with laser extinction method.

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Lean combustion is effective to increase thermal efficiency for gasoline internal combustion engines. This study focused on nitrogen oxides emission of homogeneous lean charge spark ignition combustion. The effect of high tumble intake port and high-energy spark ignition system on NOx emission was already shown. This paper reports analysis of cycle-to-cycle variation of NOx emission and combustion characteristics. Larger stretch of spark plasma cycle creates higher concentration NO emission. Shorter combustion duration cycle creates lower concentration NO emission. Cycle-to-cycle NO emissions on lean limit condition include less than 10ppm NO emission cycles considering NO emission by spark ignition.

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To correspond to the issues of climate change and energy security, the engine thermal efficiency has been enhanced by expanding combustion limit. Enhancing turbulent combustion is important to expand combustion limit. In the previous paper, it is shown that the fuel components improve turbulent burning velocity of engine combustion and expand lean combustion limit. In this paper, new fuel components including gasoline surrogate fuels are studied and it is found that characteristics of fuel’s laminar burning velocity has strong correlation with the lean combustion limit and fuel’s ignition delay time characteristics effect on knocking characteristics of SI engine combustion.

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Because of the regulation related to the global environment, the automotive powertrain system becomes smaller to increase fuel efficiency and to decrease CO₂ emission. Meanwhile, the operating condition of the gear components become tough under the higher transmitted load caused by downsizing. It becomes, therefore, more critical for automotive industry to insure the durability of the components as per the trends. In this work, the development of the material for the planetary gear system was performed to improve the durability of the gear in the downsized auto-transmission system. The metallic composition was designed to 1) improve resistance of the gear to softening phenomenon by heat generation during operation 2) insure the superior carburizing properties under the conventional heat treatment condition, and 3) improve the strength and toughness by optimizing Si, Cr, Ni and V. As a result of this development, it was shown that the characteristic L₁₀ for the roller pitting fatigue test was increased by more than 200% and the bending fatigue limit was increased by 15%.

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Safe and robust battery is urgently requested today for power sources of (hybrid) electric vehicles (HEV and EV), and thus an increasing interest developed around all solid-state lithium ion battery (LIB). One of critical internal cell resistance stems from electrode composite, where Li ion and electron conduction is required. In the conventional LIB using liquid electrolyte, electrolytes in the micro-pore and carbon-particle additive in electrodes are responsible for ionic and electronic conduction, respectively. Here, we suggest that the mixed ionic and electronic conductor as an additive for electrodes to reduce internal cell resistance and increase energy density. To realize above concept, materials exploration for mixed conductors are required. In this paper, efficient and high-throughput computational approach for materials exploration is presented with an aid of informatics techniques. Li and Zn containing oxides (Li-Zn-X-O) are targeted for the demonstration purpose, in which Li and Zn ions are chosen for ionic and electronic conduction function, respectively. We calculate ionic conductivities and phase stability (decomposition energy) of above materials by materials simulation technique, and apply Bayesian-optimization approach to find the best materials that satisfy ionic conduction and phase stability. The results showed largely improved efficiency comparing with random search algorithm.

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An electric motor driven fuel cell garbage truck was developed to reduce CO₂ emissions of a conventional diesel garbage truck and to improve the surrounding environment. One-year field test was performed in Shunan City, Yamaguchi Prefecture for practical evaluation of the fuel cell garbage truck. Based on the one-year field test data, the effect of CO₂ reduction at adaption of the fuel cell garbage truck instead of the conventional diesel garbage truck was analyzed. We also analyzed the energy consumption peculiar to the garbage truck and studied the traveling energy reduction measures suitable for its characteristics.

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In recent years, reducing the number of cylinders of an engine has been advanced for fuel saving. However, as the cylinder number is reduced, the torque fluctuation from the engine increases and the NV performance deteriorates. Therefore, the importance of torsional vibration reduction technology has been rapidly increased, and active research and development is under way. Among them, CPVA is attracted to attention because it effects in the full revolution range. In this study, focusing on the pendulum path for the purpose of improving the performance of CPVA, the influence of the path on the vibration damping performance of CPVA is clarified. In order to clarify the influence of the pendulum path, in the theoretical analysis, the pendulum path is an arbitrary path and it is represented by a 6-order function. Next, in order to verify the effectiveness of the theoretical analysis result, a multibody dynamics model corresponding to the theoretical analysis model is developed and the results of both are compared. Furthermore, theoretical analysis calculations clarify the influence of the pendulum path on the vibration damping performance of CPVA numerically.

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The relationship between motorcycle steering and roll angles was clarified in this study. A simple mathematical model for a motorcycle was developed to analyze the dynamics of the motorcycle when turning at a roll angle. Equations of motion were used to derive an equation describing the steering angle as decided by the roll angle and running velocity. In addition, a treatment method for the large roll angle of a motorcycle was described. The large roll angle was assumed as a sum of the reference and small displacement angles. The proposed method allows simple expressions for treating large roll angles. Numerical analyses using real motorcycle specifications were performed. The results show the effectiveness of stability factors on actual steering angles.

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This study deals with the standing stability of two-wheeled vehicle at stopping condition and at extremely low speed. Most of studies on vehicle behavior for two-wheeled vehicle are studying for characteristics beyond medium speed, and analyses on extremely low speed and stopped state characteristics have hardly been performed. However, on ordinary driving situation, riders need to control the vehicles at such an extremely low speed. In this research, we study the construction of equations of motion used for such speed region. As the first step of this research, geometrical relations at the time of stoppage of a motorcycle is analyzed, and a method of developing to an equation of motion is shown based on this. Eigenvalue using the equation of motion based on this result was carried out. Next, we examined the stabilization of standing stability using state feedback. As a result, it is possible to show the stabilization of standing at stopping.

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This paper considers personal mobility vehicles with lean mechanism. We performed an analysis of the influence of some sudden steering input on the tire contact performance with the roll motion by simulation analysis using multi-degree-of-freedom vehicle dynamics model for three type model (3 wheels and Rear Steering, 3 wheels and Front Steering, 4 Wheels and Front Steering). The results of the analysis showed the relationship between the dynamic response of roll motion with lean mechanism and two control method of the lean mechanism. Then We have proposed performance improvement methods by applying the closed loop lean control model and applying the unstable zero transfer function to the front wheel steering.

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In this paper, energy optimal control theory is applied to steer by wire system (SBW). In the framework of usual optimal control theory, it is difficult to realize optimal control concerning energy regeneration and motion control simultaneously. The author proposed the energy optimal control theory it enables to control energy regeneration and motionmost suitably. Energy saving effect by SBW is small, but energy regeneration control acts the big role in a motion control aspect. Themeaning of the evaluation function and the control law are made clear. The relation between the control parameters and the vehicle parameters are analyzed, the generation mechanism of emergent steer and the improvement of the vehicle motion performance are made clear. This emergent steer in the situation of energy regeneration mode seems like counter steer which skillful driver does, and very excellent stability is made by this steer.

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The authors have proposed the Two-Step structure design method for noise and vibration reduction based on vibration energy propagation analysis, which utilizes both analytical SEA and structural intensity analysis. In this paper, the Two-Step design method was applied successfully for the vibration reduction of a T-shaped plate structure and each design step was verified consistently by both FEM and hammering test. Especially, it was confirmed that a newly-devised FRF test method with damping sheet attached on the test-specimen can simulate a structure with heavy damping ratio of 0.1 and show the good agreement with the FRF calculated by FEM.

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ACM reduces body vibration to decrease vibration of under point in engine mount. Recently, gear of transmission needs higher connection to increase more powertrain efficiency. But engine vibration transfers more to body from front wheel driveshaft. We construct new ACM control for reducing the engine vibration transmission to the driveshaft without new parts adding. The new ACM control decreases body vibration to control vibration from engine mount and driveshaft at 2 control point away from 2 engine mount.

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Active Control Engine Mount (ACM) power variation increases with ACM power increase and it may affect vehicle ride comfort. This ACM power variation hike is caused by a temperature dependence of a linear solenoid that drives the ACM. In order to suppress temperature dependence, the relations of the linear solenoid’s plunger position, ACM power, and ACM control parameter were analyzed. As a result, it was found that ACM driving duty of ACM control parameter was affected by temperature dependence of the plunger position. The ACM power temperature dependence was then suppressed by using ACM driving duty during feedback control.

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This paper describes a way of thinking about analyzing the vibration characteristics of a component by using multiple sinusoidal input . The amplitude of the input is obeyed beta distribution being nearer natural phenomenon. The characteristics of plural inputs are to be reflected by one waveform. By using this input data, the time of test is shorten than the case of using the data of real road surface. When we checked this result by using Bayes statistics, it was revealed that variance of the mensuration consequence was small.

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A vent tube is used for discharging high pressure hydrogen from a hydrogen cylinder in FCV maintenance and dismantling work. In this study, two vent tube systems are tested to discharge safely. As a result, it was confirmed that the hydrogen concentration is less than 1Vol.% at 8 m away from the vent tube, where the influence of the flame on the surroundings is limited even if it ignites hydrogen gas by any accidents. It was found that backfire into the vent tube does not occur until about 30 minutes after release stoppage.

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The purpose of this study is to examine the mechanism of head rotation and the effects of cyclist helmets on the reduction of brain injury risk in A-pillar impact in car-to-cyclist collisions. Finite element analyses where a car model collided with a helmeted and unhelmeted human model placed on a bicycle model were performed. In this simulation, the occipital region of head impacted on the A-pillar. Although the helmet can reduce impact force, angular velocities of the head and moments of force applied to the head remained high because of direct contact of the occipital region of head to the A-pillar and bottoming out of the helmet liner. It was found that there are some cases that helmets cannot reduce brain injury risk in A-pillar impacts

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For the reduction of minor neck injuries during rear-end impacts, an advanced dynamic test method using the BioRID-II dummy has been discussed for the UN ECE/WP29/GRSP/GTR No.7. This study focused on certification tests for the BioRID-II dummy in order to reduce differences in the responses of dummies used in dynamic tests. Currently, a new certification test with head restraints intended to increase the flexion behavior of the dummy neck has been discussed. Therefore, in this study, the certification test with head restraints was conducted under various conditions to investigate the feasibility of increasing the flexion behavior of the dummy neck.

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In order to obtain theoretical backing to prevent the injury accident, the possibility of collision at the time of passing through the intersection was theoretically obtained. The possibility of collision was derived as a function of the own vehicle speed, the crossing vehicle speed, the lateral distance between the road and the maximum deceleration. From the obtained theoretical equation, the following were derived as necessary to make the collision probability zero. Regarding the possibility of collision, as the vehicle speed increases, the possibility of collision at the front of the own vehicle increases proportionally. As the possibility of the side of the vehicle increases as the own vehicle speed increases, it is desirable to increase the speed in the latter half of passing through the intersection to escape promptly. It is important to keep lateral distance that cancels the possibility of two items above.

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In this paper, a back scattered light analysis was applied to quantify the slipperiness of road surface. Back scattered light spectra of water film have remarkably decreased intensity at wavelengths around 1400 nm to 1600 nm. On the other hand, in the case of ice, it becomes minimum at around 1500 nm and shows peak at 1400 nm. This phenomenon is due to the difference of the peak wavelengths of the absorption spectra of ice and water. The intensity obtained by dimensionlessizing the backscattered light at 1400 nm with a value of 1500 nm, is the highest for ice.

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To perform simplified study of occupant displacement and chest deflection of THOR dummy under full width frontal crash test, two-dimensional degenerated model was created. The model was constituted from four rigid bodies, which represents head, upper body, sternum, and lower body. The translational spring was used between upper body and head, and same between upper body and sternum. The rotational joint was used between upper body and lower body. As a result, as for chest deflection and displacements of head, upper body, and lower body, similar results were obtained comparison with actual test results.

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In this study, such kind of experimental tests were conducted. Normal drivers who were using the automated driving system on the highway had to take over manual driving in the two situations, one is exit of the highway and the other one is occurring a failure of the automated driving system. In each experimental cases, the ego-vehicle approached to other vehicles just after taking over manual driving. From experimental data of driving behavior, we studied important items for safe taking over manual driving.

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Pedal misapplication crashes has been a social issue. Statistics data identified about 6000 pedal misapplication crashes occur in Japan per year. A U-shaped function shows significant over-involvement by both younger and older, especially over 75 when crash involvement is plotted against age. Despite many findings on statistical analysis, the mechanism of pedal application errors hasn't become clear. This study focused the mechanism of pedal misapplication from the point of view of human factors. Analysis of foot placement in look over left and right shoulders indicated that changes in posture would be potential sources of biases in foot aiming.

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With the recent introduction of visual-driving-support systems (i.e., camera monitoring systems), the driver-viewpoint degrees of freedom are increasing and are expected to increase further in the future. However, it remains unclear how drivers’ spatial cognition increases when a different viewpoint is added to the driver’s usual subjective viewpoint. Thus, we examined the influence on spatial cognition through experiments. As a result, the features of each viewpoint were found, and it was suggested that in the case when the proper use situation was clear, the spatial cognition was enhanced, but the case of uncertainty does not necessarily enhance unconditionally.

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The purpose of this study is to explore the consciousness and structure about driver’s traffic safety competence. A survey was conducted on 540 drivers. We carried out the confirmatory factor analysis based on the driver’s responses, and 3 factors were identified: F1, competence for danger anticipation; F2, competence for safety conservation; F3, competence for coping with accident. We found out that the consciousness structure of driver’s traffic safety competence includes these three components.

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This study proposes a haptic shared control (HSC) which provides torque on a steering wheel in order to avoid a collision with forward obstacles. The torque is calculated based on deceleration for collision avoidance (DCA) and lateral acceleration for collision avoidance (LACA). Moreover, this study also constructs an advanced driver-assistance system by a combination of the HSC and an automatic collision avoidance control law on a driving simulator and verifies the effectiveness of the proposed system.

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This study analyzed driving behaviors on transition from automated to manual driving in take-over requests (TOR). Using a driving simulator, behaviors of three driving instructors were recorded at merging and leaving sections of expressway. As a result, the mechanism of driving behaviors on the transition was examined by using the three-term behavioral contingency which described the relationships between behaviors and environmental factors. Finally, this study revealed the change of behaviors in the situation of TOR in comparison with that in manual driving, and revealed the influence of permissible time on the transition.

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A pedestrian darting out from occlusion is a typical scenario in community roads, and conventional autonomous emergency braking systems reach their limits as the sensor cannot detect the pedestrian in time. The system needs a proactive braking based on predict the possibility of pedestrian appearance as well as estimate the pedestrian motion in advance. In this paper, the acceptability of elderly drivers experienced the proactive braking intervention system in community road is investigated by analysis of driving behavior and questionnaires. From results of the investigated, the acceptability of the system was positive trend and suggested correlate with comprehensive factors from results of questionnaires.

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Abstract: The number of transportation fatalities which are caused by inattentive driving is high. For this reason, studying methods to estimate driver state while driving, such as physiological indexes and driving behaviors, is important. However, there is still no established method for detecting inattentive driving with high accuracy in real time. Therefore, the authors of the current paper constructed a personalized preventive safety system according to drivers’ characteristics. In this study, the authors aimed to construct a personalized preventive safety system that can contribute to safe driving regardless of a drivers' state when approaching common traffic accident scenes. Results showed that the personalized preventive safety system was accepted by drivers and improved safe driving behaviors, when the driver was faced with a hazardous event.

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The dynamic contact angle is important for predicting the motion of droplets by mean of numerical simulation. However, a well-known dynamic contact angle model , such as Hoffman et al. ⁽³⁾, can not predict the behavior of droplets accurately. In this study, we experimentally visualize the dynamic contact angle of droplets and calculate the flow field by numerical simulation. Then we propose the dynamic contact angle model for the low capillary number.

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Wind noise increases and disturbs passenger comfort as crosswinds generally produce strong vortices around A-pillars and door mirrors. Aeroacoustics simulations using nonlinear equations split from compressible flow equations are performed to visualize how the wind noise is generated and propagates in conditions with/without a crosswind. Although the crosswind strongly increases wind noise from the A-pillar, the waves that reach the side window mainly originate from the door mirror and not the A-pillar. These directional characteristics of the wave emissions are demonstrated by drawing acoustic stream lines.

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In the present study, we conducted wind tunnel test of simplified vehicle model that show hysteresis of aerodynamic drag during a transient change of aerodynamic yaw angle. Under some conditions where aerodynamic yaw angle fluctuates continuously, time-averaged aerodynamic drag of the simplified vehicle model changed significantly from the quasi-steady evaluation. This time-averaged drag change was considered to be mainly caused by the hysteresis of aerodynamic drag. Based on the time-series measurement of base pressure distribution, we indicated the strong relationship between the drag hysteresis and the variation of flow separation point on the model’s rear-end corner at the leeward side.

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In real driving emissions (RDE) tests, not only emissions but also fuel economy performance can be measured. The comparison between the fuel economy in RDE test using the same routes and in actual real world drivings was investigated. Tests were conducted by using two direct injection turbocharged gasoline passenger vehicles with onboard fuel consumption measurement tool based on OBD information. As a result, correlations between the fuel economy in RDE test using the same routes and that in the real world were found in many parameters except that the driving rate in highway was higher in RDE test than in real world driving, leading to better fuel economy.

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Delayed fracture property is one of the most important problem for the application of high strength steel sheet to the automotive parts. Conventionally, U-bending specimen has been commonly used for the evaluation of delayed fracture. However, the results, such as time to fracture, of U-bending specimen tends to fluctuate, and there is a possibility that the deformation state does not correspond to press formed automotive parts. In this report, V-bending specimen is proposed for the delayed fracture test. FE-simulation of U- and V-bending showed that V-bending is expected to accurately evaluate the delayed fracture properties of actual automotive parts.

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The turbocharged systems in automotive engines have a physical restriction called a surge constraint and actual machines of the systems have always uncertain parameters, which cause the system to violate the constraint. Therefore, the reachability analysis of the systems is an important task for its safety verification. In this paper, we propose a reachable set computation method for general nonlinear systems with uncertain parameters based on the sensitivity analysis. By employing the sensitivity analysis, the proposed method approximately computes the set in an efficient way. Finally, we apply the proposed reachability computation method for the turbocharged systems.

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