Hydrogen engines can utilize many technologies built on existing internal combustion engines, and retrofit modifications are also possible. In this paper, characteristics on thermal efficiency and exhaust emissions with developed turbo-charged MPI multi-cylinder ICE using hydrogen fuel modified from diesel ICE were reported. The brake thermal efficiency and NOx emissions characteristics at the operating points equivalent to the WHSC mode were obtained. As a result, engine-out NOx emission level was very low and a potential to below the latest regulation limit at steady operating conditions was acquired.

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“Temperature swing” by heat insulation coating is a technology developed to reduce heat loss in diesel engines. The purpose of this study is to evaluate the fuel film thickness formed on the piston surface with heat insulation coating. A 1-dimensional heat transfer model is developed and the inside temperature distribution of the piston at the compression TDC of the first cycle of a diesel engine during cold start is estimated. The inside temperature distribution of the piston can be reproduced by instantaneous heating with a pulsed laser. The fuel film thickness is evaluated by applying the refractive index matching (RIM) method. When the piston is instantaneously heated with the pulsed laser, the fuel film thickness decreased by 15 % compared to no heating condition.

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In this study, we focused on the eco-driving of electric heavy-duty vehicles. The target vehicle is an electric truck developed by our research team. Using the parameters of the truck and developed speed pattern optimization simulator, we derived EV eco-driving speed change patterns. Compared to eco-driving of diesel vehicles, we found several different characteristics. Specifically, we examined the details of the result “acceleration interval with allowed strong acceleration,” which was significantly different from that of diesel vehicles. We confirmed with chassis dynamometer measured data that the strong acceleration of EV will not cause significant deterioration in vehicle efficiency.

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A community bus was modified to an EV, and a 9-month field test was conducted on a mountainous route in Fukushima Prefecture. According to the test data under various driving conditions such as urban, suburban, and mountainous areas, as well as weather conditions including various ambient temperature and solar irradiance, the effects of each factor on the electric consumption of PV-equipped vehicles were analyzed. The calculation model was developed and validated by comparing with the vehicle test data, and the potential of energy consumption reduction through the onboard PV system and its contributing factors were evaluated.

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We propose a forward-gazing model for path planning (Preview Path-Planning model) as the most basic model that provides insight to people who share the paradigm of human-like path-planning modeling. The basic concept is to apply a low-pass filter to changes in forward curvature. In addition, the phase delay due to the low-pass filter is compensated by forward gaze. We also report the results of determining the longitudinal motion by applying the GVC technology to the situation in which the vehicle could run perfectly along the path.

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In recent years, the automotive industry has become more sophisticated and complex, making it difficult to detect issue at an early stage. The developments process is becoming more fragmented and divided into labor, and it is important to be able to extract and share issues at each process under development. In previous developments, it has been difficult to analyze and share intersystem interference. In this document, we were able to confirm its effectiveness in system development using an analysis method of intersystem interference based on MBSE’s (Model-based Systems Engineering) concept. The analysis method made it possible to perform interference analysis at the early stage of development, and it was possible to proceed with development based on a common understanding among the parties concerned.

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This paper presents a fabrication and evaluation case study of a full-scale multi-material automotive semi-monocoque prototype. The prototype is composed of Variable Axial Composites (VAC) and aluminum inserts fabricated using nano-unevenness anodizing bonding technology. The basic design process involves multi-material anisotropic topology optimization and interpretation as manufacturing data. The 3D mold shape is manually defined and developable preform surfaces are placed to fill the mold cavity. The fiber path is automatically generated using the Turing Pattern algorithm based on the optimization data. The preforms are fabricated using the Tailored Fiber Placement (TFP) process, which uses a CNC embroidery machine to realize local fiber orientation control. The preforms are stacked in the mold and molded together with aluminum components by Vacuum Assisted Resin Transfer Molding (VaRTM). Experimental evaluations were conducted to assess the static stiffness of the prototype, and the results are compared with a conventional aluminum design.

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In order to reveal the vibration propagation phenomena in systems consisting of coupled structures with large dynamic stiffness differences, we propose a modal energy propagation analysis method that evaluates the vibration power flow between eigen modes. This method can extract modes with high contribution to the vibration power flow. In this report, we present the results of applying this method to a coupled system of a car body and trim part and verifying its validity.

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The ram pressure is lower than the total pressure of the cooling fan in stationary or low-speed vehicles, and the heat is typically managed by the speed of the cooling fan or opening the enclosure. However, the long-term noise exposure to the working space can be a problem due to stationary or low speed operation. In this paper, the opening search technique for the enclosure using the adjoint method has been proposed to solve the dilemma between heat management and noise control.

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It is necessary to estimate the injury of occupants during car accidents to estimate the effect of injury reduction performance of autonomous driving systems. Although there are some estimation models of injury of occupants based on logistic regression, logistic regression has the problem of being unable to express nonlinear relationships between explanatory and objective variables. In this study, we used LightGBM, a decision tree model, and our own selected explanatory variables to construct an injury prediction model to predict the probability of VAIS3+ of vehicles. It showed a significant improvement in performance from URGENCY.

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The simulation modeling for CMT arc-welded joints using shell elements applicable to full vehicle crash analysis was developed for predicting fracture behaviors. A measuring method of mechanical properties in welding induced heataffected zone was proposed by applying simulated thermal cycles to ultra-high-strength steel. The peak temperature range of several simulated thermal cycles with furnace heating and enforced cooling was from 773 to 1073K, where material softening occurs. The stress triaxiality dependent fracture strain was obtained using tensile test results at two stress states. The predicted results by developed shell model agreed well with the experimental force-stroke history and fracture location.

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In the present study, we proposed the information provision systems using icons shown on the meter cluster and guide lights shown on the road surface as a speed adjustment support to encourage smooth merging behavior by drivers traveling on the main road using ACC. To verify the effectiveness of two types of information provision systems, an experiment was conducted with 26 participants using Virtual Reality headset-based Driving Simulator (VRDS) . It was found that the icons and the guide lights assisted judgment of acceleration and deceleration behavior, and enabled smooth merging.

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Waste Heat Recovery (WHR) System which converts exhaust heat into power was evaluated on actual vehicles. as a result, WHR system tuned exhaust heat into power and the fuel consumption was improved 1.6 % in highway mode. The fuel consumption improvement effect by mounting a retrofit system of exhaust heat recovery and power regeneration was confirmed. This report describes the process of the examination and the results and problems of the system.

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During collisions, base metals may incur ductile fracture without evident defects under complex stress conditions. Herein, we propose a test method for evaluating the initiation behavior of internal ductile cracks in metals under shear stress conditions. The applicability of the developed specimen to the evaluation of ductile crack initiation condition was discussed based on the results of tensile fracture tests and finite element analyses. It is found that the critical equivalent plastic strain for crack initiation was lower in the shear stress state than the tensile stress state under equivalent stress triaxiality conditions.

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We constructed a numerical analysis model of hardness and residual stress distribution considering phase transformation during quenching. Using the model, we estimated distributions of hardness and residual stress in the induction hardened shaft. The accuracy of the model was confirmed by comparison with the experimental data. Moreover, through the numerical simulations of induction hardening under various conditions, we also considered the relationship between the case depth and the residual stress distribution.

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ESD protection devices are now becoming more and more important in electronic devices in automotives to improve safety and security. In this study, discharges between terminals are observed by the ESD visualization camera and the cycle test of ESD revealed repeated ESD protection ability. We propose MLCV as the most suitable ESD protection device through a comparison with MLCC, which is commonly used in automotive electronics. MLCV demonstrated excellent protection ability against repeated ESD (＞25 kV), and kept less suppression voltage (150 V at ESD 8 kV), caused no discharge between terminals, with less size (1005M).

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This study aims to develop a methodology for evaluating the potential of passenger and delivery transportation. The method uses facility location and population distribution information to represent terminal traffic and home delivery trips, and extracts human flow trips that can be combined with home delivery trips using the Delivery Efficiency Criteria. The evaluation showed that efficiency can be maximized by selecting consolidation areas within a delivery efficiency criterion value of 0.8 to 1.0. The method allows for the visualization of Origin-Destination of difficult-to-move trips, aiding in route setting for freight and passenger consolidation transportation.

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It is known that the appropriate welding current range (WCR) in resistance spot welding of aluminized hot-stamped steel sheets is influenced by heating conditions prior to the hot-stamping. In this study, the thermal and electrical contact resistance between hot-stamped surfaces in the resistance spot welding is modelled considering the mechanical, thermal and electrical characteristics, which are dependent on the multi-layered coating structures evolved during heating. Developed contact resistance model is incorporated to the resistance spot welding simulation, to show that longer dwell time narrows the WCR as experimental results show.

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Port Fuel Injection (PFI) system in hybrid gasoline engines is frequently in cold condition due to use for electricity generation. Under cold condition, the fuel film forms on the intake port wall does not evaporate completely during the cycle, and the injected fuel spray impinges on it in the next cycle. In this paper, the process of fuel film formation under multi-cycle fuel injection condition is analysed by applying the Total Internal Reflection Laser Induced Fluorescence method. In addition, the particle size distribution of spray droplets was measured in quiescent conditions with Super High Spatial Resolution Photographymethod, which allows for whole spray imaging while maintaining the spatial resolution of small droplets. As a result, the fuel adhesion mass per injection increases as the critical Weber number increases with repeated fuel injections under quiescent conditions. Under cross flow conditions, fuel mass impinging on the wall is much smaller than under quiescent conditions. Accordingly, the fuel adhesion mass per injection is almost constant with repeated fuel injections because of the small increase in the critical Weber number.

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Multi-component fuel depositions and evaporation behaviors of high pressure DI fuel sprays on a heated plate are measured by means of an exciplex fluorescence technique. Temperatures, distillation characteristics and thicknesses of deposited fuel films are calculated from ratios of two wavelength fluorescence intensities and a DMA doped fluorescence intensity as an additional donor molecule for exciplex. Fuel deposition and evaporation behaviors are explained under different wall temperatures and fuel pressure conditions.

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Analyzing the cause of degradation in the aftertreatment system of diesel engines is of utmost importance. This report focuses on comprehending the impact of hydrothermal degradation each aftertreatment catalyst installed in a diesel engine, and how it affects the overall performance of the aftertreatment system. To achieve this, numerical calculation was conducted using a hydrothermal degradation model. Analysis of the simulation results revealed that the emission behavior of various gas components is significantly affected not only by the degradation of the selective catalytic reduction catalyst, but also by the degradation of the diesel oxidation catalyst and diesel particulate filter.

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This paper describes the impact of communication latency (delay) on drivability in remote driving systems, with the aim of expanding the Operational Design Domain (ODD) of remotely controllable automated driving systems. One effective way to expand the ODD is to increase vehicle speed. Understanding how delay affects vehicle behavior and determining an acceptable level of delay are important. In this paper, a driving simulator capable of controlling delay is used to perform specific tasks and correlates delay with driving ease. Through analysis of driver steering operation and yaw-rate, the relationship between driving ease and vehicle behavior is clarified. Additionally, a man-machine simulation model is defined to expand the experimental conditions and reveals the mechanism of vehicle behavior under delay conditions. Finally, the appropriate acceptable level of delay needed to achieve the desired vehicle behavior is clarified.

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To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for stable combustion. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline. In the present study, the antiknocking effect of adding methane with the RON of 120, ethane with the RON of 108, or propane with the RON of 112 to a regular gasoline surrogate fuel with the RON of 90.8 has been investigated. Adding each gaseous fuel by less than 0.4 in heat fraction advances knocking limit in the descending order of SI timing advance of ethane, methane, and propane, and in the descending order of CA 50 advance of ethane, propane, and methane. Adding methane extends combustion duration slightly, but adding ethane or propane shortens it considerably. Shortening combustion duration has a negative effect on advancing knocking limit SI timing. The effect on advancing knocking limit CA 50 is dependent on not the RON’s of the gaseous fuels, but the rates of OH removal by the gaseous fuels. The antiknocking effect of adding each gaseous fuel to a premium gasoline surrogate fuel with the RON of 100.2 has been also investigated. The effect on advancing knocking limit CA50 is not dependent on whether the liquid fuels have cool-flame reactions or not.

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While the electrification of passenger cars is essential to reducing CO2, but current electric vehicles face challenges higher vehicle prices due to the increased battery capacity on board, the time/frequency of charging, and short driving range. Dynamic Wireless Power Transfer (D-WPT) is recognized as one way to solve problems. However, because D-WPT coils transfer power using electromagnetic fields, there are concerns about the effects on the human body. In this paper, Electromagnetic Field(EMF) evaluation was conducted using a vehicle equipped with a 150kW DWPT coils that reduces magnetic field leakage, and the maximum value was expected to meet the standard.

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Dynamic wireless charging of electric vehicles (EVs) will significantly extend the range of EVs, thus increasing the potential for electrification of passenger cars. In this study, we propose copper strip wire as an alternative to litz wire. By using copper strip wires, it is possible to improve the coupling coefficient and Q value, and improve the transmission power while keeping the size of the primary and secondary coils small. We designed a controller driven at frequencies of 79-90kHz using SiC IPM and evaluated its operation through simulations and experiments. The measured energy efficiency was 90% in the on-vehicle state, and 150kW was output when the efficiency was 86% in a large tolerance condition.

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It is important for tire developers to clarify the judgment basis of subjective evaluation results. In this research, we constructed a machine learning model that uses sensing data related to the driver’s perception and operation as input and subjective evaluation as output. The model combined ESN and random forest to clarify important features and timings from whole time series data of all features. The internal state of the ESN was taken out at an arbitrary timing so that it was input to the random forest, and the subjective evaluation values were predicted. Prediction of the values at lane change showed sufficient accuracy. From the importance of the feature values, it was found that the steering torque in the early stage of lane change, the steering angle and steering torque in the middle stage, and the movement of the head in the late stage. The approach used in this research can clarify important features and timings, so it can be applied to various situations using time-series data.

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The topology optimization helps realize highly-rigid yet lightweight vehicle bodies for lower CO2 emissions. We developed a largescale nonlinear topology optimization method that simultaneously addresses linear (torsional stiffness and vibration) problems and nonlinear (crashworthiness) problems to control energy absorption by the vehicle body structure during a collision. The optimization of the entire vehicle body model produced a rigid truss-like structure, and all the objective functions converged to the desired level. Consequently, an optimal shape that can be used as a reference for designing a car body frame structure and that simultaneously satisfies stiffness, crashworthiness and NVH performance requirements was obtained.

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Brake operating noise are caused by brake pipe vibration due to pressure pulsation of the ESC modulator pump, and pressure pulsation is amplified by standing waves in the brake pipe. The ESC modulator pump characteristics, which are difficult to calculate from the ESC modulator specifications, were experimentally identified using the “2 pressures/2 systems” method. Using the ESC modulator pump characteristics identified by this method, we developed the 1D model that can predict the standing waves in the brake pipes.

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In this paper, we propose a method for raindrop removal from rain-drop coated images acquired during nighttime rainy weather. To the best of our knowledge, no previous deep learning-based method for raindrop removal has been developed for nighttime images. This is because it is difficult to identify raindrop regions in images acquired at night, making it difficult to remove raindrops, and there is no nighttime raindrop image dataset to train a deep learning neural network.To solve these problems, we propose a method to create nighttime raindrop images from daytime images without raindrops by using a deep learning based semantic segmentation method and a method used in the field of computer graphics. In order to improve the ability to identify raindrop regions, we propose a GAN architecture that incorporates the U-shaped Transformer structure into the GAN generator. In addition, we propose to apply histogram flattening to the input images as a preprocessing step during training so that the GAN can be trained stably on a nighttime raindrop image dataset. Experimental results are presented to verify the effectiveness of the proposed method.

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This study aimed to test the hypothesis derived from a previous report suggesting that improving walking ability can reduce the occurrence of foot position errors, such as stepping on the accelerator instead of the brake. We implemented a supervised walking ability improvement program in a group of 30 elderly participants and analyzed its effects. Over a 12-week period with at least three sessions per week, the training program significantly improved balance function and walking ability, leading to a significant reduction in foot position errors. Additionally, the study confirmed that the elderly responded positively to the program.

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The measurement of consumed hydrogen weight in the off-board gas cylinder is a common approach to measure the hydrogen consumptions of light duty vehicles. Concerning hydrogen consumption measurement of heavy-duty vehicles, this approach is not realistic because the amount of hydrogen consumption is larger than that of a light duty vehicle. Therefore, an approach which directly measures the amount of mass flow of hydrogen from the cylinder to the powertrain system is studied. In this paper, the accuracy of measured results of the mass flow of hydrogen and the challenges to improve the accuracy will be discussed.

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Evaluation of delayed fracture property is one of the major barriers for application of high strength steel sheet to automotive parts. We are proposing a delayed fracture evaluation method using four-point bending test piece. In this study, we reported that it was possible to investigate the maximum unfractured stress of steel sheets with shear edge by using four-point bending specimen. In addition, it was clarified that the shear clearance and shear angle, which were shear conditions, greatly affected the delayed fracture resistance of steel sheets. The reason for the change in the delayed fracture resistances was estimated to be the change in the amount of the dislocation, vacancy or residual stress at shear edge of steel sheets by the shear condition.

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Electric vehicles are increasingly using larger-capacity batteries, and battery temperature management is an issue. For this reason, water cooling systems with high cooling efficiency are adopted. This report describes the results of evaluating the corrosion resistance of various surface-treated steel sheets to the cooling water used in water cooling. The cooling water resistance of each plated steel sheet was evaluated, and aluminized steel showed the best cooling water resistance. It was also found that aluminized steel have a smaller corrosion current density and larger impedance due to immersion in LLC. From this, we found that aluminized steel is applicable to cooling channels.

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The Japanese Industrial Standards (JIS) specify the adhesive strength 𝜎 𝑐 𝐽𝐼𝑆 (ℎ) as an average ultimate tensile stress by using a small specimen without considering the adhesive thickness ℎ. In this paper, the validity of 𝜎 𝑐 𝐽𝐼𝑆 (ℎ) is investigatedwhen 𝜎 𝑐 𝐽𝐼𝑆 (ℎ) is used to evaluate the strength for larger adhesive area 𝜎 𝑐 𝑊 (ℎ) from the ISSF (Intensity of the SingularStress Field). Then, it is found that when ℎ in the JIS test specimen is equal to ℎ in actual products, 𝜎 𝑐 𝐽𝐼𝑆 (ℎ) can be usedsince 𝜎 𝑐 𝑊 (ℎ) = 𝜎 𝑐 𝐽𝐼𝑆 (ℎ). This is because the ISSF of actual product is controlled by the adhesive thickness ℎ independentof the adhesive area.

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Ensuring dimensional accuracy has become difficult with the increasing application of ultra high strength steel sheet to the automotive parts. Generally, the cross section of an automotive part is U-shaped or hat-shaped, and a wavy spring-back, one of the cross section opening, occurs in the wall of curved-in-top view part in conventional bending process. Wavy spring-back is caused by difference of the degree of wall curl along longitudinal direction and its main factor is stress difference in thickness direction of the wall, caused by bending-unbending deformation at the die shoulder. To ensure the dimensional accuracy of the cross section, spring-back prospection to the negative angle is necessary, that increase forming process and costs. In order to resolve this issue, a new forming technology is developed that can suppress factor stress by applying inplane compression to the cross sectional direction. In this research, spring-back suppression effect is investigated by press trial and FEM analysis.

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In recent years, the risk of cyberattacks on automobiles has increased with the proliferation of connected cars. In order to properly deal with cyberattacks on automobiles, it is necessary to analyze logs obtained from automobiles accurately and promptly. In this paper, we propose a log analysis framework for automobiles that specifies logs to be analyzed to identify the cause of cyberattacks on automotives. We applied the proposed framework to a sample system and confirmed that the number of log types to be analyzed was reduced by 18%.

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