The multicomponent fuel model, which estimates vapor-liquid equilibrium and physical properties of fuel mixtures, can represent heterogeneous fuel concentration distribution due to differences in evaporation characteristics of two-component fuel spray. In this paper, the concentration distribution characteristics of each component of a two-component fuel spray were measured by laser-induced fluorescence method and numerically calculated using the multicomponent fuel model with fuel injection pressure and ambient density as parameters.

View full abstract

A high-accuracy knocking prediction model with low computation loads is necessary for the efficient development of SI engines using engine performance simulators. In the first report, the scientific nature of autoignition prediction using the Livengood-Wu integral was investigated. In the second report, ignition delay time equations for a premium-gasoline surrogate fuel were developed to reproduce the temperature-, pressure-, and equivalence ratio-dependences of ignition delay time produced using a detailed reaction mechanism. In the third report, error factors in in-cylinder autoignition prediction using the Livengood-Wu integral with the ignition delay time equations were investigated. In the fourth report, an autoignition prediction model using “reverse Livengood-Wu integral” with the ignition delay time equations and an error correction equation was proposed. In the fifth report, the ignition delay time equations were improved to reproduce the EGR-dependence of ignition delay time. In the present report, the ignition delay time and error correction equations have been revised. The reverse Livengood-Wu integral with the revised equations has been applied to predicting HCCI’s and end-gas autoignitions produced using the detailed reaction mechanism under different conditions without and with EGR. The present model can be effective in decreasing errors in the prediction.

View full abstract

The scatter-band data to decide the engine hard specification in the early development phase is constructed. As L2 (Level) requirement, thermal efficiency, combustion stability, oil dilution and soot are defined. The average operating conditions are set from mass-production engines and the parameters in L2/L3/L4 are defined empirically. The scatter-band data related to the time loss for thermal efficiency is shown and is confirmed that the connection of parameters are related. For utilization, the system characteristic analysis is performed to understand of the position in scatter-band. From the result of the analysis, the turbulence is enhanced by piston top bowl shape optimization.

View full abstract

Pyrochlore type CeO₂-ZrO₂ materials with high heat resistance of crystal structure have been put into practical use to impart “slow and high” oxygen storage capacity to catalyst. Further improvement over three generations realized high functionalization, and it succeeded in greatly improving NOx purification function. The reduction of precious metal amount in the catalyst was achieved by the development material.

View full abstract

Reducing soot emissions at cold start and warming up phase is a major issue for exhaust gas regulations in gasoline port injection engines. The purpose of this study is to clarify the soot reduction mechanism by heating the parts around the intake port and to reduce soot emission. By constructing and evaluating the heating method with a high soot reduction effect, the prospect of about 40% soot reduction effect was obtained.

View full abstract

HC-SCR system by diesel reformed gas was developed to improve a NOx reduction performance. A low temperature oxidation of diesel fuel was adopted to generate a diesel reformed gas such as oxygenated hydrocarbon, which is high NOx reduction agent. Various experiments for evaluating NOx reduction performance were conducted using n-hexadecane and diesel fuel by changing a reforming temperature, reforming equivalence ratio and NOx: HC mole ratios in the selective catalytic reaction. It was found that the NOx reduction efficiency by reformed gas was achieved up to about 90%.

View full abstract

The occurrence of cavitation in fluid machinery such a torque converter causes problems such as damage to components, increased noise, and reduced performance. A technique for forecasting these issues at the design stage would benefit industry. In this study, a gaseous cavitation model was introduced into a commercial flow analysis software “STAR-CCM+” to numerically simulate the void fraction in a torque converter. The applicability of the gaseous cavitation model to torque converters was verified by comparing the calculated results with experimental results where erosion occurred. The results show that the model is valid because it reproduces the position of blade erosion under conditions where it is difficult to determine the onset of cavitation from the change in torque converter characteristics.

View full abstract

In order to extend an environment of a vehicle performance prediction, such as diversification of a powertrain and driving scenarios, and to improve an accuracy of vehicle performance prediction considering a transient behavior of the powertrain without increasing computational resources, it is necessary to select a model with appropriate granularity. In this study, we propose a method to integrate scenario-based vehicle model with fast running engine model.

View full abstract

In the 2020 fuel cell stack, the hydrogen supply piping has been simplified with the aim of reducing costs and mounting space. A hydrogen mixing pipe was newly installed to eliminate the insufficient mixing of supplied hydrogen and circulating hydrogen caused by this simplification. A two-phase flow simulation was used to design a hydrogen mixing pipe that can both prevent the inflow of circulating water into the fuel cell and mix hydrogen.

View full abstract

This article describes the evolution of the high-pressure hydrogen storage system parts developed for new fuel cell vehicles (FCVs) with the aim of helping to further popularize FCVs. New high-pressure hydrogen tanks with three different lengths were developed to store the necessary amount of hydrogen in the system without sacrificing the interior space of the sedan-type vehicle. Mass-production capabilities were increased and major cost savings were achieved by adopting new machining methods for the high-pressure valves. Assuming that the system might be refueled at a wide range of refueling stations in the future, a crank-shaped flow path was adopted in the solenoid valve to discourage the inflow of water, and notches were added on the moving sliding parts of the solenoid valve in six locations to reduce the adhesive force between the walls and the moving part in freezing temperatures. The structure of the piston was also simplified from three to two layers by enabling direct sliding with the regulator body by improving machining method. As a result, high-pressure regulator costs and weight were reduced. The same high filling efficiency as the previous system was maintained despite the adoption of three tanks with significantly different volumes by measures such as optimizing the hydrogen injection angle inside the tank. In addition, the developed tanks and valves obtained certification under United Nations Regulation 134 (UN-R134), which was established to allow mutual recognition of FCVs and other vehicles.

View full abstract

The previous model is equipped with FC stack assembly under the floor of the car, but the new model is equipped consolidated FC units in the engine compartment. It results in great mountability equivalent to that of conventional engine. In order to achieve equipping FC stack in the engine compartment, it is necessary to enhance G resistance and miniaturize FC stack at the same time. In order to secure reliability of high voltage safety and hydrogen safety, it is necessary to control cell seal leakage caused by cell deviation. We adopted external constraint structure, in addition to the friction constraint force between each cell, to control quantity of cell deviation in less than quota. As the external constraint structure, we installed silicon rubber called Filling in the gap of FC cell stack and stack case. It results in enhancement of G resistance by 1.6 times compared to the previous model. Optimizing the rigidity of stack case and the gap size between cell stack and stack case is necessary to control external constraint force using Filling. The new stack case is made by FSW (Friction Stir Welding) line joining of upper and lower case, which are made by casting respectively. This case structure achieves the requirement written above and miniaturize stack at the same time. In the FC stack manufacturing process, the stacking process of 330 cells was automized. It realized stacking cells with high dimensional accuracy at the shorter cycle time. It results in reduction of cell deviation and contribution to control the gap between cell stack and stack case, and control external constraint force.

View full abstract

Although the additional centering torque proportional to the provisional lateral acceleration (PLA) has been proposed for personal mobility vehicles (PMVs) those tilt inward according to the steering angle, it has not been clarified how to give hysteresis that greatly affects the driver's feeling. In this paper, the counter torque proportional to the actual tilting angle is proposed to cancel the excessive hysteresis caused by the delay in inward tilting motion of the vehicle, based on analyzing the factors those cause steering torque hysteresis such as vehicle behavior. This makes it possible to secure the adjustment allowance for steering friction in the actual vehicle.

View full abstract

In order to improve airborne noise in mid frequency, this paper proposes an efficient and fast simulation method in consideration of panel vibration modal characteristic. Firstly, because the panel vibration mode can increase/decrease the sound radiation, a new index called “Equivalent radiation power with phase-cancellation” is proposed to consider the effect of the modal characteristic onto panel transmission loss. Then, transmission loss of acoustic trims is also remodeled with transmissibility of the trim. With those proposed in this paper, airborne transfer function at mid frequency is simplified. The accuracy/benefit are discussed along with comparison of conventional solution and test results.

View full abstract

Object tracking is important for autonomous driving. Extended Object Tracking (EOT) is the method that simultaneously estimates both object motion state and shape, and is more robust than tracking object as a mass point. In order to apply EOT to autonomous driving on actual public roads, we should consider its specific problems. For example, considering object shape changes caused by changes in the visible range and tracking many objects in real time are necessary. In this paper, we propose stable and real-time EOT that can be applied to actual public roads, and verified usefulness of the proposed method.

View full abstract

Glare is a visual experience of discomfort and low visibility caused by strong lights. Using electroencephalography, we investigated neurophysiological responses associated with glare. By comparing event-related potentials (ERPs) between the trials in which participants experienced glare (“Glare”) or not (“No glare”) from visual stimuli with the same physical brightness, we identified ERP components specific to subjective glare. In the right lateral-occipital (latency: 95–105 ms), left lateral-occipital (134–305 ms), and anterior-prefrontal (181–191 ms) areas, ERPs exhibited significantly greater potentials for the (“Glare” trials than for the “No glare” trials.

View full abstract

Public transportation is required to have effective measures against the new corona infection. In this study, we investigated the actual condition of ventilation, which is said to be the infection route of the virus, and examined the countermeasures in addition, the behavior of the particles when they were diffused into the route bus was measured. PSL and artificial saliva were used as the particles. PSL tends to be deposited easily, so the particle concentration is too low. It may lead to evaluation. Also, the particle collection ability of the aerosol filter was evaluated. From this result, it was found that it has the same effect as window opening ventilation.

View full abstract

Hydrocarbons in gasoline vehicle exhaust, such as alkenes and aromatic hydrocarbons, have potential for ozone formation in the atmosphere. To develop a high-performance three-way catalyst for reducing the amounts of these hydrocarbons, simple and real-time measurement techniques of hydrocarbons based on structural classification are required. In this study, real-time measurement techniques of hydrocarbons in gasoline vehicle exhaust, based on distinction of structure, were developed using Fourier transform infrared spectrometric (FT-IR) and photoionization mass spectrometric methods. Using a standard gas of blended hydrocarbons, the fundamental measurement methods were constructed. By comparing with existing techniques, such as GC-MS, it was confirmed that hydrocarbons classified by structure in exhaust emitted from gasoline vehicles can be efficiently measured using both measurement techniques.

View full abstract

C-SMC (Carbon fiber - Sheet Molding Compound) is formed by mixing carbon fiber with a long fiber and resin. The fiber distribution becomes uneven in the part due to the resin flow during manufacturing. Therefore, it is more difficult to grasp the signs at the time of fracture and the growth of cracks than other CFRPs. In this paper, we performed C-SMC tensile strength test and C-SMC structural component test with loading / unloading cycles by acoustic emission and reported the result of evaluation and application of Kaiser effect for C-SMC.

View full abstract

A novel concept of an energy system “virtual grid” in which renewable electric power such as photovoltaic power generation (PV) is stored and transported efficiently by using electric vehicles (EV) has been proposed. Previous research of the virtual grid has shown that CO₂ emissions can be reduced economically in an integrated model of the home, private EV and the workplace. In this paper, buses that travels between the station and the workplace are electrified, and the effect of an energy system integrated between private EV, electric buses (EB) and the workplace is studied and is expanded upon from previous research. As a result, by introducing this system, about 90% of the power consumption of EB can be replaced by PV power. In addition, in the energy system integrated with PV, EB, private EV, and the workplace, under the condition that the PV surplus generation rate is constant, the CO₂ reduction effect increases as the integration becomes larger.

View full abstract

Oil dilution is a serious problem in post injection. When constructing a model that predicts oil dilution, handling oflubricating oil film in wall impingement model is difficult. Therefore, we investigated the influence of the lubricatingoil film thickness on the fuel deposition amount, using the Laser Induced Fluorescence Method. As a result, it wasfound that when the non-dimensional film thickness (δnon= δoil/din, δoil : lubricating oil film thickness, din : fuel dropletdiameter) is less than 0.24, that is, when the lubricating oil film thickness is less than 3.4 μm, the fuel depositionamount is same to that of the dry wall.

View full abstract

Jet configuration of a multi-hole nozzle spray for gasoline port injection is a liquid sheet. In this paper, novel modeling scheme of the generated droplets is reported. The spray atomization process is modeled using linear stability theory in liquid jet, including the injection feature of the liquid sheet, the breakup process of the liquid sheet, and the breakup process from ligaments to droplets. In addition, a model is proposed to provide the droplet size distribution using the statistical theory of uniform turbulence. As a result, it is found that the droplet generation length coincides quantitatively in the region where the wave growth rate is higher. However, due to the nonlinear effects of waves, the prediction accuracy of large droplet generation is reduced. Therefore, the experimental results of droplet generation length were used to correct the breakup time. The droplet size distribution modeled using the corrected breakup time can represent the atomization effect with changing fuel injection pressure.

View full abstract

In Japan, the Ministry of Economy, Trade and Industry formulated the "Green Growth Strategy with Carbon Neutrality in 2050 ", they decided to maximize the use of renewable energy. Also, the spray characteristics such as macroscopic shape and particle size in diesel engines are important for understanding combustion. Therefore, in this study, we grasped the spray characteristics using fatty acid methyl ester (FAME) as conventional BDF and Bio Hydrofind Diesel (BHD) as next-generation BDF. As a result, the BHD resulted in a low penetration and high dispersion spray compared to the FAME, suggested an improvement in thermal efficiency and emissions.

View full abstract

When calculating indicated mean effective pressure (IMEP), it is necessary to measure the original cylinder pressure correctly. Generally producing calculation error is known, if IMEP is calculated from pressure diagram with which top dead of center (TDC) detection position deviation. In this paper, it cralified about effect to which TDC detection position deviation exerts on IMEP calculation result from pressure diagram by which fourier series expansion was carried out using solicited method, and its cause.

View full abstract

In this study, a global kinetic model for Standard SCR reaction applicable to Cu-CHA and Cu-AFX under steady state conditions was developed and the simulation results in Standard SCR reactions over honeycomb catalysts were compared with test data. The Cu-AFX also showed the same Standard SCR reaction scheme as the well-known Cu zeolite catalysts have. The reaction scheme and the model for Standard SCR reaction over various types of Cu zeolite catalysts were proposed.

View full abstract

In the Urea-SCR system, two-dimensional visualization images of spray droplet taken by a high-speed camera are used for verification of atomization and measurement of droplet diameter. This paper describes the method for predicting the droplet diameter from visualization image with depth of field using deep learning to improve accuracy of measuring droplet size distribution. As a result from trained model, this method showed applicability to measure droplet within various depths.

View full abstract

It is known that the tooth profile circular used in the reduction gear “single-tooth pinion gear” that achieves high efficiency and high speed reduction has a higher degree of influence on performance due to changes in the center distance than involute tooth profiles. In this paper, we verified the influence of the change in the center distance of the single-tooth pinion gear on the transmission efficiency. It was also confirmed that the influence of the change in the center distance on the transmission efficiency can be reduced by changing the tooth profile.

View full abstract

Electric Vehicles are expected to be widespread for reducing CO₂, however there are many issues. On the other hand, Hybrid Vehicles are already widespread. Dynamic Wireless Power Transfer for Hybrid Vehicles can be one of the effective means to improve the actual electric driving rate, however precise control of receiving power is required because of small allowable battery power. In this paper, we propose power control method by transmission inverter and PWM AC/DC converter, and show results of power control on high-speed rotary bench at 40km/h,

View full abstract

This article describes the evolution of the high-pressure hydrogen tank developed for the new FCV with the aim of helping to further popularize FCV. New high-pressure hydrogen tanks with three different lengths were developed to store the necessary amount of hydrogen in the system without sacrificing the interior space of the sedan-type vehicle. Some of the lightest tanks in the world （weight effectiveness :approximately 6.0wt%） were developed by adopting a new high-strength carbon fiber that reduced the fiber content of the tanks. Mass-production capabilities were increased and major cost savings were achieved by adopting a newly developed fast-curing epoxy resin for CFRP and high-speed machining processes used in the tanks while ensuring high quality. In addition, the developed tanks obtained certification under UN-R134, which was established to allow mutual recognition of FCV.

View full abstract

Dynamic wireless power transfer has been proposed to solve the issue of performance problem of electric vehicles, which is a short cruising range. There is the eddy current loss in the conductors, which is in the magnetic field by the wireless power transfer system. This research reveals the influence on the efficiency of wireless power transfer by road structures with the road embedded transmitter coils. The reinforced concrete reduces 4.5% of coil efficiency. The aluminum shield plate of the transmitter coil can improve coil efficiency with reinforced concrete. However, it reduces coil efficiency on the soil pavement. Road embedment also reduces coil efficiency.

View full abstract

The acceleration caused by vehicle motion is applied to passenger body as an inertia, then it affects to ride quality. Therefore, we had explored the possibility to control passenger body motion with both lateral inertia generated by steer control and longitudinal inertia by driving force control (acceleration and deceleration). We have taken the resultant inertia effect into consideration, then verified its effect for passenger body motion with experiment. Derived physical passenger body motion model are used to derive optimal vehicle movement to minimize passenger motion. Experiments based on optimal simulation verified the possibility to control passenger body motion more effectively.

View full abstract

Extension of the applicable range of the method of quantitatively evaluating the steering characteristics with the primary delay parameter τL of the identified driver model using the steering angle and traveling locus at the time of lane change is studied. In this report, the same vehicle motion (lateral motion and yaw motion) is realized by a driving simulator, and the evaluation results are reported in which only the driving environment factors such as the holdability of the driver’s seat are changed.

View full abstract

We have announced a method to calculate the temperature frequency data that the interior parts of the vehicle are exposedto from the weather history data. This calculation requires the Vehicle-specific constants obtained from the short-term actualvehicle exposure test. However, if the vehicle does not exist in the planning stage, we propose a new method for obtaining thevehicle-specific constant from the design dimensions.

View full abstract

The purpose of this study is to understand the actual situation of pedestrian crashes in Michigan (U.S.) and to create a scenario of fatal injury. Accident analysis was conducted based on the VIPA (Vulnerable Road Users Injury Prevention Alliance) datasets, and the accidents scenario were extracted from detailed field investigations and subsequent assessment of pedestrian kinematics. It was found that the fatal accidents of pedestrians while crossing the road were occurred with a passenger car at night. The detailed accident was analyzed in terms of AIS (Abbreviated Injury Scale) severity by body region and the frequency of AIS 3+ injured body regions were shown at head, thorax and lower extremity in a nighttime. The distribution of contacts were higher at head, thorax and lower extremity injuries from windshield, hood surface, and hood edge, respectively. In addition, injuries to the thorax and the lower extremity of AIS 3+ were observed only at night and the configuration of injuries were differed between day and night.

View full abstract

Accurate occupant injury prediction is important for Advance Automatic Collision Notification in accidents. In previous report, it was found that vehicle body deformation information was needed to improve injury prediction. This paper studied vehicle body deformation factor for occupant injury prediction in side impact crashes using an accident database in the U.S.(NASS-CDS) and constructed injury prediction model using those factors. As a result, roof deformation factor is found to be important for improving injury prediction model. The analytical method using photos of deformed vehicles was considered to measure the roof deformation in NASS-CDS accident cases. Roof deformations with 30 cm and above have a higher odds ratio of 2.944 compared to those below 30 cm. Therefore, this factor is considered to be included in injury prediction model with sensitivity improved to approximately 88% from the conventional model.

View full abstract

This paper presents a technique to measure and position a toe board during car crash tests. The three-dimensional deformation of the toe board marked with dots is measured using stereovision. As the stereovision fixed to the car vibrates in a crash, observed deformation includes motions of the stereovision itself. By mounting the stereovision on a sensor suite that contains gyros and a camera facing downward, the suite measures the position of the stereovision with respect to the global frame and allows the positioning of the toe board. The effectiveness of the proposed technique was validated in the actual car crash test.

View full abstract

Recently, road projection lamp systems that present information on the road surface have been developed for the purpose of improving driving safety. However, it is still unclear how the driver's gaze behavior and visual attention are influenced by the road projection lamps. Therefore, in this study, we evaluated the effect of road projection lamp in terms of the driver's gaze behavior and visual attention when various types of road projection lamp were displayed through the driving simulator study. The results revealed that the non-directional road projection (exclamation mark) attracted the driver's gaze around the projection, making the driver pay attention to a wider area.

View full abstract

In the present study, we conducted a questionnaire survey to clarify the effects of the COVID-19 epidemic on the physical and mental health of elderly people and the changes in the feelings of elderly drivers toward driving. The number of outings, which decreased during the period of emergency declaration, gradually recovered to the level before COVID-19 epidemic. However, the number of outings for leisure and social activities did not recover. The number of times they used public transportation decreased, and the number of times they used cars driven by others increased. In addition, the number of times they drove by themselves decreased slightly, and their anxiety about driving by themselves increased. Furthermore, communication with others was association with mental health in the elderly. There is concern that the COVID-19 epidemic may cause a decline in quality of life in the elderly.

View full abstract

In order to evaluate the risk of contact between vehicles ( mutual accident risk ), it is necessary to be able to predict the trajectory of the vehicle and probabilistically represent the area where the two trajectories interfere with each other within a certain period of time. Therefore, in this paper, we propose as a method to evaluate the mutual accident risk in the real traffic world by utilizing the vehicle trajectory data observed that has the rectangular information of the vehicle to deal with the tasks.

View full abstract

In structured environments, steering control of autonomous driving is almost performed by using localization based on lane markers. However, in off-road environments, there are no lane markers and the road boundary is detected by some sensors. The boundary is not smooth and automatic steering control based on the detected boundaries has problems. In this paper, path following control with the nonlinear weight of lateral errors is proposed. The lateral error is derived from the boundary which is detected by using deep learning. In conclusion, it was confirmed by actual vehicle experiments, the proposed method worked well on agricultural roads.

View full abstract

This study proposes a low computational-cost design method for ride comfort. The point of the proposed method is to replace the computationally expensive multibody dynamic calculation with the computationally reasonable eigenvalue analysis. To establish the method, we focused on the analogy of the eigenmodes with the features extracted by PARAFAC decomposition from the obtained results with the multibody dynamic calculation. As a result, it is found that the method enables the qualitative changes in the evaluation index during optimization. The proposed method has potential to reduce time for the design study of running performance including ride comfort.

View full abstract