Greater sophistication of control systems is driving an increase in the number of sensors installed in the engine. In response, the authors are working to develop a virtual temperature sensor that can operate on the ECU in order to reduce cost and monitor sensor reliability. This paper reports on a virtual sensor that estimates exhaust manifold gas temperature and the response model for the actual temperature sensor. The model for estimating exhaust manifold gas temperature was prepared based on the equation of energy conservation in the cylinder, and variation in indicated thermal efficiency is expressed by an empirical formula based on the measurement results. In addition, the response delay of the actual temperature sensor is modeled as a second-order transfer function with variable time constants, and variations in the time constants are calculated based on the heat transfer model. Estimated accuracy was checked in simulation of transient test cycle, and the proposed model was confirmed to have adequate accuracy as a virtual sensor.

View full abstract

A diesel combustion calculation code has been developed and it is currently used for our actual engine development. But the code has one weak point. In some injection patterns including pilot injection or pre injection with a small amount of fuel, it can’t predict ignition delay time precisely. That is because the ignition delay time is figured out by the Livengood-Wu integral method. Therefore the changing from the simple method to chemical kinetics calculation using an elementary chemical reaction model was tried out. The overview of our chemical calculation and some knowledge from observing the ignition delay time differences between the current simple method and the chemical kinetics calculation are shown in this report.

View full abstract

A novel approach based on the chemical kinetics has been applied to elucidate the ignition phenomena in spray combustion. Cetane number was suggested to correlate with the ignitability of fuel-rich mixtures (not with those of stoichiometric mixtures), or with the cool-flame ignition delay time. A fuel-air adiabatic mixing model was used to estimate the local equivalence ratio of the mixture which is most relevant to the ignition of fuel spray. Also, the effect of the possible mixing of gas parcels with different equivalence ratios and thus different history of oxidation was discussed based on the simplified model calculations.

View full abstract

Recently Pre-Ignition in Premixed Combustion Engines are reported in many studies. Pre-Ignition is assumed to be caused by lubricant oil (LO). But, LO auto-ignition condition and the potential of LO auto-ignition on Pre-Mixture ignition has not been clarified. Therefore, this study focuses on the auto-ignition of LO and the ignition of Pre-Mixture induced by auto-ignition of LO. The experiment was conducted by Rapid Compression Expansion Machine (RCEM) to simulate engine operating condition. From experimental result, LO is able to ignite Pre-Mixture gas under engine operating conditions. Pre-Ignition (ignition of Pre-Mixture by auto-ignition of LO) can be inhibited by decreasing equivalence ratio and temperature of Pre-Mixture or increasing engine speed.

View full abstract

In order to develop a compact and low-cost ammonia meter for research, development and evaluation of urea-SCR (Selective Catalytic Reduction) systems for diesel exhaust after-treatment, a prototype optical measurement instrument that consists of a near-infrared (1510nm) fiber-coupled tele-communication diode laser, a multi-pass absorption cell (path length 13.2m), and a compact lock-in detection module was designed and constructed. Calibration tests using room-temperature N₂-diluted ammonia sample gases successfully demonstrated the instruments’ linearity over a concentration range from 1ppm to 1600ppm with few percent repeatability and 0.5sec measurement response. The real-time measurement of 50ppm or 1600ppm ammonia diluted with diesel-exhaust was successfully demonstrated.

View full abstract

A novel 0-dimensional engine simulator called UniDES has been developed through a series of studies. In actual cases of multiple-injection, prior sprays can affect the ignition and combustion characteristics of following sprays. This study used a new spray-to-spray interaction model to estimate the burned gas rate with respect to the total gas entrained in a following spray. This model also considers spray deflection due to swirl flow and wall impingement. It was confirmed that the new model is capable of reproducing spray interaction behavior, as well as accurately predicting heat release rates and exhaust gas conditions such as temperature and HC concentration.

View full abstract

2D concentration distribution is an important factor to analyze the combustion structure and the combustor efficiency in engines. For example, 2D distribution of NH₃ becomes a key factor for the process of denitrification in urea SCR. The purpose of this study is to establish the 2D concentration measurement technology using CT tunable diode laser absorption spectroscopy(CT-TDLAS). The characteristics of 2D measurement concentrations of CH₄ were analyzed and compared to the sampling results. The time resolved NH₃concentration in the engine exhaust gas were also measured to demonstrate the capability of CT-TDLAS in engine applications.

View full abstract

2D temperature and concentration distribution plays an important role for the combustion structure and the combustor efficiency in engines, burners and so on. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a computed tomography (CT) method using absorption spectra of water vapor at 1388nm. The CT tunable diode laser spectroscopy methods were applied to burners to measure 2D temperature distributions. The two dimensional temperature measurement technology in high temperature condition using 1343nm and 1388nm have also been discussed to demonstrate its applicability for various types of combustor.

View full abstract

The effect of waste heat recovery (WHR) on fuel consumption of a high boosted diesel engine was predictively evaluated. The available energy of waste heat has a big potential to improve brake thermal efficiency (BTE). The maximum BTE by WHR was predicted 55.0 % at full load operation (Ne=1600rrpm), if available energy is converted into effective work without any losses. On the other hand, the conversion efficiency of combined cycle is fairly low. So, the improvement in fuel consumption by combined cycle was estimated 3.4% at full load operation (Ne=1200rpm).

View full abstract

It is important to specify the paths of oil flow up for reduction of lubricating oil consumption (LOC) in reciprocating engines. In this study, transparent cylinder liner made of sapphire is used for observing the behavior of oil-flow-up. Oil film thickness and oil film velocity are measured with laser induced fluorescence (LIF) method and particle image velocimetry (PIV). As a result, it is determined the thickness of oil on the piston land and the velocity of oil flow through the piston ring gap. It is also found out that the accumulated oil on the top land is scattered over combustion chamber.

View full abstract

Since the engine combustion is affected by various engine parameters as well as fuel characteristics, it is very difficult to find out the clear effect of fuel property on it. In order to clarify the change of emission characteristic caused by fuel trend, we propose a fundamental flame research method using a small pool flame system. Number concentrations and exhaust rate of PM emitted from laminar diffusion flames of gasoline fuels (JIS No.1 and No.2) and hydrocarbon fuels of various chemical structures such as alkane, alkene, iso-alkane, iso-alkene, cyclo-alkane, cyclo-alkene and aromatic were investigated by SMPS (Scanning Mobility Particle Sizer). In addition, relation between PM exhaust rate and RON (research octane number) was discussed.

View full abstract

To reduce calculation errors of FFT based Nyquist plots in fuel cells under electrically noisy environments, a space-average noise reduction algorithm was applied instead of traditional time-average noise reduction algorithm. With an appropriate M-sequence input signal conditions and data sampling frequency, Nyquist plots of frequency ranging from about 0.38 Hz to 10 kHz were obtained about every 3 seconds including calculation time, etc. Maximum impedance percentage difference between the space-average FFT methods and comparable FRA method was less than 6%. By using the space-average FFT methods, Nyquist plots in transient states such as step responses and ramp responses were obtained. Also, Nyquist plots during US06 drive cycles were obtained about every 3 seconds.

View full abstract

The engine load of a commercial hybrid truck is reduced by using assist of a hybrid electric motor. Fuel economy of this hybrid truck is improved with the assist. On the other hand, exhaust-gas temperature is decreased, and it has a negative effect on the purification performance of aftertreatment system. In this report, firstly, fuel economy and exhaust -gas emission of an actual commercial hybrid truck were measured by chassis dynamometer. Secondly, control methods to improve fuel economy and exhaust-gas temperature of the hybrid truck were investigated by using "Hybrid power -train test bed system". The results show that the engine of the hybrid truck was operated in the range of high efficiency, fuel economy and exhaust-gas temperature of the hybrid truck were improved, compared to a diesel truck.

View full abstract

This paper introduces an innovative electric power distribution system for residences that is inspired by power management systems for electric vehicles. To counteract the negative impacts of climate change on a global scale we need to build a sustainable society that can accelerate the transition from fossil fuels to renewable energy sources such as wind or solar. However, renewable energy sources such as wind power or solar power are intermittent and difficult to predict. Thus, it is difficult to maintain the balance between energy supply and demand on energy systems and it makes electricity distribution a challenging topic. On the other hand, in recent years many global auto companies are releasing EV, PHV or FCV into the market. We could take advantage of this evolution as a potential solution for the previously mentioned demand-response issues that arises when using renewables. In this paper we study an autonomous DC microgrid system concept based on renewable energies that uses electric vehicle technologies such as bidirectional DCDC converters with intermittent operation. We built real-time simulations of the microgrid system that show a renewable energy replacement ratio of up to 85% under proposed system conditions.

View full abstract

To enable to design vehicle response under force control, this paper aims to obtain symbolic parameters dominating vehicle response. Factoring the characteristic equation under force control, which is described by a quartic equation of Laplace operator s, under some assumptions, this paper formulates the exact solutions. Considering these formulas, this paper obtains the symbolic parameters dominating vehicle response.

View full abstract

Because of transparency of ice, it is difficult to measure the profile of ice surface by optical method such as laser scanning. We propose the method that whitens the ice surface by rapid cooling spray so that stable reflecting laser beam on ice surface leads successful profile measurement. We conducted the full braking test on iced road of in-door tire tester at a temperature around 0℃. And we made a study on relationship between the resultant cross sectional profile of the ice surface damaged by tire treads and resultant frictional characteristics of the tire on the ice. Results shows that the friction of tire on ice has well correlation on cross section of the ice surface damaged by tire treads.

View full abstract

This paper concerns the modeling of autonomous trucks that run sensing the lateral deviation and relative attitude to the lane of express way. As actual roads consist of cants and curves, vehicles that run the roads are given the lateral forces caused by the cants and curvatures. “Relative Cant” involving the influence of the forces is defined and built in the models. The availability of 3DOF model to simulate an actual truck performs the cant-lane keeping run being given the necessary steering wheel angle calculated by the Algebraic model as a control model.

View full abstract

"Multiple sinusoid" is composed of sine waves, the frequencies of which are FFT's analysis frequencies. This paper describes an effectiveness of a method using the "multiple sinusoid" for the input of frequency response analysis of vehicle dynamics. In an example installing aerodynamic parts to a vehicle, such a minute difference of frequency characteristic has be extracted that is not able to be detected by the conventional method i.e. impulse response or step response.

View full abstract

Analysis using transfer functions and the characteristic equation quickly gives us solutions of vehicle transient response problems. However, it usually does not tell us the physical background and the underlying mechanism. To address this shortcoming, complex plane vector representation is a useful approach. Application of it to the vehicle model transfer function requires a small contrivance in representation of the denominator as explained in this paper. With this help, it is possible to clearly show the total view and mutual relationship between various frequency responses.

View full abstract

To improve ride comfort at smooth road, rising part of hysteresis on suspension wheel stroke curve has to be designed to avoid an increase of dynamic stiffness at very low amplitude due to friction. Rubber bush is one of components that cause hysteresis. However, there is no appropriate method to investigate the influence on dynamic performance of suspension system by designing specification. This paper proposes a rubber bush model that is used for suspension dynamics design in early phase of vehicle development by investigating dynamic specification of rubber bush without detailed design.

View full abstract

The authors have developed a steering real-time simulator that is a bench test method for steering system using a Hardware-In-the-Loop Simulation (HILS) to improve the efficiency of the steering system development. In this study, a suspension model based on a multibody kinematic analysis was developed to improve the accuracy of tie rod axial force calculation in the real-time simulation environment. The evaluation of the developed multibody kinematics model was carried out by comparing the calculation results in the off-line simulation with those of commercial software and reproduced tie rod axial force in the HILS test with those of actual track test.

View full abstract

This paper describes a full vehicle model for model-based development of a future light weight electric vehicle using Modelica language to evaluate both vehicle dynamics and energy consumption. Modelica language has a beneficial feature that allows various engineering fields to be simulated simultaneously in a unified model. Utilizing this advantage, the model was composed of a vehicle, control systems, a torque vectoring driveline, and motors/invertors, with considering each loss. Simulations of a driving straight ahead in crosswind and a steady state cornering were carried out, and the results clarified the trade-off relationship between vehicle attitude and energy consumption, and the breakdown of energy consumption quantitatively.

View full abstract

It is effective for suspension performance improvement to evaluate ride comfort objectively by separating vehicle vibration to each wheel input. In this paper, it is described that an experiment with plural vehicle velocity condition on the road that include plural wavelength enables transfer function calculation to each wheel input. Also it is confirmed that calculation of vehicle vibration under any road input at any vehicle velocity is available with calculated transfer function.

View full abstract

Modification of the compliance of the suspension mounting points does not always reduce road noise. Body input forces are sometimes affected by characteristics of the suspension mounting points via a mechanism which is still unknown. In this study, the transfer function synthesis method was used to examine the mechanism of change in body input forces. The compliance balance between suspension arms, bushings and mounting points was shown to be an important factor in changing the input forces. Judging whether the compliance of the suspension mounting points should be reduced, make it possible to clarify directions for countermeasures for road noise.

View full abstract

One of the important issues in brake-squeal analyses using FE models is the reproducibility of the phenomena and the measures for minimizing natural-frequency differences between measurements and simulations for each of the components are crucial to the improvement of the reproducibility. In the evaluations of model-measurement correlations in the study of brake discs, if amounts of shifts in natural frequencies and their deviation orientation, between measured and simulated, varies in each vibration mode, the gaps in natural frequency cannot be adequately reduced by adjusting density and/or Young’s modulus. In this paper, we examine the effect of residual stress in motorcycle discs on natural frequency by X-ray stress measurement and simulation considering stress stiffening.

View full abstract

This paper examined the requirements for frequency component or volume of warning sounds in the hearing experiments of sample warning sounds of Approaching Vehicle Audible System (AVAS) in an actual vehicle. The following facts were clarified. The high-frequency component in warning sounds cannot travel a long distance. The warning sounds should be measured from various directions and distances to the vehicle. Audible distance becomes longer when the difference in the sound pressure level between the warning signal and the ambient noise in any band is larger.

View full abstract

To achieve advanced control of automobiles, such as automatic platooning control, it is needed to know values of parameters of the vehicle. It is demanded especially in controlling trucks, since the mass and the inertia change widely according to the loaded condition. Then the authors propose to estimate the yaw moment of inertia of the truck on real time during travelling. Dual Kalman filter, which estimates the state variables and values of the parameters simultaneously on real time, is applied to the method. The results of the numerical simulations show the proposed method is effective for the estimation.

View full abstract

An experimental method and specimens were proposed in order to determine a triaxiality-dependent fracture criterion of advanced high strength steels in the crash simulation of automotive bodies. Some crash tests and simulation results indicated the fracture occurred near the edge or ridge area of the body parts where the stress states are between uni-axial and plane strain conditions. In order to evaluate the fractures and their producing strain states, several types of simple tensile specimens were designed and the local strains during tensile test were measured with a digital image grid method (DIGM). To compute the stress triaxiality and fracture strain, FEM simulation models for several types of tensile specimen with three classes of advanced high strength steels were developed. The relation between fracture strain and stress triaxiality was obtained. The effects of material strength, element types and mesh size on both the stress triaxiality and fracture strain were investigated.

View full abstract

We investigated the patients who lost consciousness while driving and transported to our emergency room by ambulance from July 1995 to December 2013. 215 patients were included in this study, 175 male and 40 female, from 13 years to 88 years old. There were 32 bicycle riders and 10 motorcycle riders and 173 automobile drivers, with average injury severity score of 2.5±5.5. There were 80 patients with epilepsy attack, 65 patients with stroke, 32 patients with cardiovascular attack. These 215 patients were 2.6% of all drivers who were transported to our emergency room after traffic accident during the same period. Conscious loss attack while driving is not so rare, and proper medical care for patients with driver’s license must be considered.

View full abstract

High frequency of fatal head injuries of the elderly is one of the important issues in traffic accidents in Japan. While a human head/brain FE model is a useful tool to investigate head injury mechanism, there has not been a research result using a model considering the structural and qualitative changes of the brain by aging. In this research, to get the basic knowledge to consider a new injury criterion for brain injury of the elderly, the generational difference of intracranial responses related to traumatic brain injuries (TBI) under impact loading was clarified using age-specific human head/brain FE models.

View full abstract

In recent years, the traffic accident shows gradual decreasing in the number of fatalities, whereas slowly decreasing the total number of accidents and injuries. In order to decrease the total number of accident, it is necessary to investigate what kind of accident has happened. So the feature of crossing collision with bicycle at non-signalized intersection was analyzed from traffic accident data. For further details, vehicle speed and position of the driver's foot of sudden braking, traffic environment factor to delay the discovery of the bicycle, and so on were clarified by using near-miss incident database collected with the drive recorders.

View full abstract

When the multiple driving support systems are installed in a vehicle, it is important to inform a driver of multiple information as the driver can understand each information appropriately. In this study, we proposed the presentation method of the two different information using the driver’s peripheral vision when the two different information is presented from a vehicle-infrastructure cooperative system at a blind intersection without a signal. To reduce the cognitive workload of the multiple information, the first-priority information was presented on the head up display (HUD) for the driver to understand the first-priority information certainly and quickly. On the other hand, the second-priority information was presented in the peripheral display installed in the driver’s peripheral vision to recognize the second-priority information without gazing easily. By using the peripheral display in addition to the HUD, the driver’s response time to the second-priority information was reduced significantly without a negative effect on the response time to the first-priority information.

View full abstract

The relationship between driving behavioral indexes and near-miss events was made clear for the purpose of developing a method of quantifying safe driving assessment based on accident risk. This study focused on right-turn accidents, which are the second most intersection accidents in Japan. Candidate driver behavioral indexes were considered based on typical accident patterns. Using a database of everyday driving behavior, driver behavioral indexes having a significant correlation with the near-miss event rate were identified. Tests were conducted to validate the indexes using an augmented reality experimental vehicle (JARI-ARV) to simulate a right-turning vehicle approaching an oncoming vehicle ahead.

View full abstract

The purpose of this study was to investigate relationships between characteristics of driver behaviour without a potential collision situation and collision avoidance behaviour with a potential collision situation. An experiment for turning to the right at an intersection was implemented by using a test vehicle called JARI-ARV. As for a potential collision situation, an oncoming straight car was presented when turning to the right at the intersection. Results showed that drivers who exhibited careful driving behaviour such as significant decreases in their own speeds had careful collision avoidance behaviour such that they passed through the intersection after the oncoming car. The opposite was also true. Therefore it can be said that there is a possibility that improving driving styles based on how to drive can contribute to decreases in traffic accidents.

View full abstract

Populations of developed nations, including Japan, are aging rapidly. It is hoped that a driving assistance method will play a role in allowing elderly people to maintain active lives and improving the traffic environment and education on traffic safety. In this study, we evaluate a driving assistance method that provides audio and visual information in a field operational test. The sound and images are presented when drivers do not decelerate or decelerate insufficiently at non-signalized intersections without right-of-way. The evaluation of the method indicates the possibility of improving driving behavior at the intersections where accidents involving elderly drivers frequently occur.

View full abstract

This paper discusses comfort estimators to construct a control system that regulates thermal comfort of a passenger in the conditions where disturbances exist. We consider two types of estimators; an observer-based estimator and an estimator with a neural network. The observer-based estimator is designed on the basis of the model proposed in our previous research. The neural-network-based estimator learns/estimates the relation between inputs and outputs regarding the system as a black box. The performance of the control system with each estimator is validated with simulations.

View full abstract

A high strength nitrided gear was developed in controlled gas-nitriding process for creating the γ’-Fe₄N phase compound layer and designing the material composition so as to minimize the hardness difference between compound layer and substrate, and to set the optimum hardness profile for the gear. The created compound layer is controlled around HV800 by low carbon steel with the Mn, Cr and V content in the material. As a result, the developed nitrided gear achieves at least 50% higher pitting fatigue strength than a conventional nitrocarburized gear, and same strength level with conventional carburized gear.

View full abstract

We developed recycled aluminum alloy for motorcycle wheels manufacturing using HPDC (High Pressure Die Casting). So far, virgin ingot aluminum has been used because the elongation property deterioration was an issue. In order to make the elongation property equivalent to the virgin ingot alloy, the optimum amount of manganese (Mn) at an appropriate solidification rate in HPDC was determined. The crystallization configuration of iron-based intermetallic compounds that affects the elongation property was controlled. As a result, 97% reduction of CO₂ emission in the material production was achieved with recycled alloy compared to virgin ingots.

View full abstract

Tｈis paper presents a road marking detection method using Light Detection and Ranging(LIDAR) intensity data by a simple template matching. Sometimes an optical camera does not produce clear enough images for road marking detection due to changing light conditions. On the other hand, the reflection intensity of LIDAR is hardly affected by sunlight or other optical conditions because LIDAR has its own light source. For this reason, the proposed method generates road surface texture images from LIDAR intensity data. The detection rate of “Speed limit 30km/h” and “Pedestrian crossing warning sign ” on public roads was 92% and 87%, respectively.

View full abstract