To achieve variable compression ratio, the multi-link system which has secondary merit as good quietness performance and low opportunity loss is selected. Under these circumstances, it is very important how to design the journal bearings and bushes which is added as important elements to constitute the multi-link system. In this paper, it is described that how to design the journal bearings and bushes for multi-link system based on each peculiar load characteristic and sliding characteristic. At that time, each dynamic characteristic and cooling effect by the engine oil by the added oil feeding path is considered.
In the future, there is a movement to reduce the number of diesel vehicles, and it is expected that diesel oil might be in excess. The purpose of this study is to propose a fuel design by mixing the surplus diesel fuel into gasoline and apply it to gasoline engines. Therefore, the macroscopic and atomization characteristics of spray by changing the fuel composition was evaluated, and we investigated the effect on wall impingement. In this report, free spray was visualized to focus on atomization characteristics and we evaluated the influence of fuel components on spray droplet diameter and droplet velocity. At the same time, it was revealed whether atomization characteristics deteriorated by mixing high boiling component can be recovered by increasing injection pressure.
Homogeneous charge compression ignition (HCCI) combustion is promising a new combustion system reducing NOx and PM simultaneously without any penalty of fuel consumption. However, the operational range of the HCCI combustion system is limited because of some issues such as poor control of ignition timing and the excessively large rate of pressure rise. In this study, a new combustion system based on the HCCI combustion process has been proposed. The combustion system has a divided combustion chamber of two parts, one is small and the other is large. On the combustion system, at first, ignition takes place in the small chamber, and then the burned gas ejected into the large chamber ignite the mixture in the large chamber. In the combustion system, the combustion process in the large chamber is aimed to go on same manner of the HCCI combustion process. This paper presents engine performance, combustion characteristics and exhaust emissions on the combustion system.
Homogeneous charge compression ignition (HCCI) combustion is promising a new combustion system reducing NOx and PM simultaneously without any penalty of fuel consumption. However, the operational range of the HCCI combustion system is limited because of some issues such as poor control of ignition timing and the excessive rate of pressure rise. In this study, a new combustion system based on the HCCI combustion process has been proposed. The combustion system has a divided combustion chamber of two parts, one is small and the other is large. On the combustion system, at first, ignition takes place in the small chamber, and then the burned gas ejected into the large chamber to ignite the mixture in the large chamber. In the combustion system, the combustion process in the large chamber is aimed to go on same manner of the HCCI combustion process. This paper presents engine performance, combustion characteristics and exhaust emissions when the small chamber volume ratio is changed under the constant compression ratio.
The aim of this study is to clarify the characteristics of diesel spray and spray flame injected with the ultra-high injection pressure of 350MPa. From the shadowgraph images obtained in a constant volume vessel, spray-tip penetration, spray cone angle, spray volume and mean equivalence ratio in a spray were analyzed. The results show that with increasing the injection pressure up to 350MPa, larger scale vortex was produced in a shear layer between spray and ambient air. As the result of the enhanced turbulent mixing, the mean equivalence ratio was decreased at the same spray-tip penetration within a short time.
The analysis method to identify reaction intermediates of combustion is proposed in this study. In the method, accurate mass of molecular and fragment ions measured by a time-of-flight mass spectrometer (TOFMS) are used for the estimation of compounds which are not be able to identify by mass spectrum data of National Institute of Standards and Technology (NIST) library. The method was verified by the discrimination of structural isomer of intermediates by low temperature oxidation of n-heptane. By using the method, it is expected to obtain unprecedented knowledge about the combustion and exhaust reaction mechanism of the engine.
We propose a new analysis method for nonlinear vehicle dynamics. The proposed method enables not only vehicle motion analysis but also control system evaluation.in nonlinear region. Until now, it was necessary to simulate vehicle evaluations one by one. In the proposed method, comprehensive evaluation is possible, not limited to specific conditions. The analysis is performed by drawing contour lines of the state velocity on the state plane. We use yaw rate γ and rear slip angle αr(= −βγ) as state variables.
We propose a new analysis method for nonlinear vehicle dynamics. The proposed method enables not only vehicle motion analysis but also control system evaluation.in nonlinear region. Until now, it was necessary to simulate vehicle evaluations one by one. In the proposed method, comprehensive evaluation is possible, not limited to specific conditions. The analysis is performed by drawing contour lines of the state velocity on the state plane. We use yaw rate γ and rear slip angle αr(= −βγ) as state variables. This paper describes the relationship between the conventional analysis method and the proposed method. The proposed method enables analysis of existing control systems and development of new control systems.
Numerical optimization of spot-welding locations by using the automotive full vehicle model was carried out to increase the stiffness of a steel car body by a conventional method which adds spot-welding points beside ones with higher strain energy, and by a newly developed topology method. The comparison of the results suggests that the topology method could be more effective than the conventional method. In addition, numerical optimization for locations of adhesives was carried out to increase the stiffness by topology method. The results suggests that the stiffness could be improved effectively by minimum length of adhesive indicated using topology optimization.
In recent years, the number of traffic accidents caused by elderly drivers has been increasing. In order to develop a driver assistance system, it is necessary to analyze the driver’s driving behavior to extract unsafe driving behavior. In this paper, we propose a method that estimates face pose and leaning forward posture by using on-board camera images. We show the example of driving behavior analysis at a blind intersection.
In our previous studies, it was suggested that inducing intrinsic motivation for driving behavior is effective in maintaining arousal level. In the present study, aiming for further optimization of this method, we examine the influence that timing of inducing intrinsic motivation gives to maintaining arousal level. Different timing of inducing intrinsic motivation depending on the arousal level was tested, and the arousal maintenance effect was evaluated. From experimental results, it was suggested that it is appropriate to induce intrinsic motivation at the timing of 60% sleepiness level at the latest to increase the arousal level most effectively.
The authors’ previous studies revealed that the bolt nut connections having pitch difference may realize fatigue life improvement and anti-loosening performance. However, the suitable pitch difference for improving the fatigue life is relatively smaller than the suitable pitch difference for improving anti-loosening performance. In other words, there is no pitch difference improving both fatigue life and anti-loosening performance. Therefore, in this paper, the effect of nut height on the anti-loosening performance is newly considered. The results show that the most suitable pitch difference for anti-loosening performance can be reduced by increasing the nut height. This nut height may realize both anti-loosening performance and high fatigue strength.
The purpose of this research is to construct a model that can predict the breakup process of direct injection gasoline spray with high accuracy. In this report, the spray breakup model was selected from the experimental analysis results of the spray breakup form just below the injection hole. The reproducibility of spray formation was verified by combining Huh and Gosman model, which is a primary breakup model that considers turbulence in the nozzle, and MTAB model assuming low-speed secondary breakup.
Narrow combustion controllability and operational range are known as issues to be solved for HCCI combustion. This study focuses on a practical solution focusing on multiple gasoline injection during the compression stroke. It was confirmed that auto-ignition timing can be advanced or retarded by forming a local ignition delay distribution depending on the fuel injection timing. Finally, by combining these functions with multiple fuel injections, a wider operatable range than HCCI combustion was successfully achieved.
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. X of the Livengood-Wu integral is no more than the ratio of an integration step out of ignition delay time. Assumed that the profiles of heat release rate along the time normalized by ignition delay times are similar, when the sum of Δt/τ reaches 1, the parts of a profile of heat release rate can be integrated to be the whole profile. In the second report, ignition delay time equations for a premium-gasoline surrogate fuel were developed, which can reproduce the temperature-, pressure-, and equivalence ratio-dependences of constant-volume 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. Errors are accumulated during the H2O2 loop induction part of ignition process. In the present report, an error correction equation has been developed, which can cancel the advances of timing predicted using the Livengood-Wu integral from ignition timing. Finally, an autoignition prediction model using “reverse Livengood-Wu integral” with the ignition delay time and error correction equations has been proposed.
So far, a diesel particulate filter (DPF) has been widely used to trap diesel soot. However, the filter would be plugged with deposited soot, resulting in an increase of filter backpressure. If the backpressure is large, the engine may stall or the fuel consumption would increase. The filter is needed to be cleaned by oxidizing the deposited soot, which is called a filter regeneration process. To reduce the soot oxidation temperature, the filter is normally coated with catalyst. For the catalyst coating, the valuable substances such as platinum are usually used. It is desirable to reduce the amount of catalysts. For that purpose, we need to know the influence of the catalyst on the soot deposition process. In this study, we have simulated the filter regeneration process and evaluated the effect of catalyst. Here, using Pt and AgPd as catalysts, the temperature field and the period of filter regeneration have been compared and discussed.
Lean or diluted combustion will be applied for improving thermal efficiency of gasoline engines. Such the engines need high air flow in cylinders to keep combustion stability. One of the issues of the engines is wear of spark plug electrode. We assumed that main factor of wear of spark plug is increase in number of re-strikes during discharge. Based on the assumption, the relationship between time distribution of the discharge energy and number of the re-strike was evaluated. We proposed a new ignition control logic which was able to reduce the number of re-strikes by about 50% compared to the conventional ignition control. This paper will describe results of durability test with and without new ignition control logic.
A feasibility of onboard PV system was evaluated by a simulation model of energy balance between estimated PV generation and vehicle energy consumption. Effects of vehicle usage patterns and weather conditions on the energy balance were discussed. Onboard PV systems have the potential to reduce amount of plug-in charging energy and Well-to-Wheel CO2 emissions of electric passenger vehicles.
This paper proposes a new control method for a large EV drive system that combines conventional motors and planetary gears. The system output torque and the difference between the two motor speeds are the target values. This controller was created by system models to enable coordinated control of the two motors. The proposed new control method was verified using a test bench in comparison with the conventional control method. The results confirmed that, unlike the conventional control method, the proposed new control method can switch modes and perform other actions without generating driving force shock.
In this study, engine and motor sounds are focused to improve the acceleration feeling of hybrid vehicles. First, the subjective evaluation is applied to grasp the impression of acceleration feeling when sound pressure levels and frequency characteristics of both sounds are changed. Next, engine speeds and sound parameters of motor sounds are changed, and then the changes of acceleration feeling are grasped. Finally, a multiple regression analysis is performed based on the results of the subjective evaluation of acceleration feeling. A new estimation model of acceleration feeling for hybrid vehicles is constructed, and its accuracy is verified by experiments.
In this research, to improve the operational feeling of the rotary switch, we investigated the construction method of the switch operation feeling model by grasping the correlation between the subjective evaluation and the physical quantity for the continuous complex stimulus of tactile sensation and operation sound. First, the impression was evaluated under a single stimulus of the tactile stimulus and the operation sound stimulus, and each physical quantity corresponding to each stimulus was grasped. Next, the tendency of the operational feeling was grasped by the impression evaluation under the complex stimulus. As a result, the operation sensation estimation model created in this study showed high agreement with the actual operation sensation.
Recently, the number of traffic accidents involving elderly drivers has been increasing, and it is known that side collisions at the intersection are particularly frequent. Thus, we put on-dash cams for 22 drivers aged 50-82 years old to measure their driving behavior at stop intersections. The relation between emergency braking frequency and looking behavior, and cognitive/physical characteristics and driving attitude were investigated. The results show that some elderly drivers can perform compensatory driving behaviors such as looking both ways at stop intersections to reduce the frequency of emergency braking even though their cognitive and physical characteristics have deteriorated.
Intake air cooling can mitigate knocking of gasoline engine which then result in improvement of fuel consumption．But intake air receives heat from the engine room while passing through the intake pipe．Therefore the sensitivity of factors such as shape and layout of parts is quantified by using inverse analysis，and the effect of these factors to intake air temperature reduction is verified.
Vehicle wind noise is an aero–vibro-acoustic coupling problem. Therefore, the wavenumber–frequency spectrum is useful to analyze flow field and vortex sound field with considering vibrations such as bending waves of a window glass. In this study, fluctuating surface pressure data on a window glass from CFD results are analyzed by the wavenumber–frequency spectrum method. Thus in this paper it is mentioned that analysis results of wind noise around a vehicle body which are caused by exterior parts to estimate input power for vibro-acoustic simulations.
In this paper, we proposed a novel technique to realize accurate and robust position estimation in urban area. The technique makes the best use of averaging effect to optimize long time (over several tens of seconds) series sensor data. Our proposed scheme uses just a low-cost GNSS receiver, a MEMS IMU, and a speed sensor. Evaluation tests in a Japanese urban area showed that our proposed scheme can realize robust lane-level absolute positioning results.
Recently, most cars are equipped with Global Navigation Satellite System (GNSS), whose deviation on a map can be larger than several meters. For level 2 automated driving, Adaptive Cruise Control (ACC) and Advanced Emergency Braking system (AEBS) require higher accuracy of self-location. In this paper, we propose a Moving Horizon Estimation (MHE) that fuses an external sensor and GNSS to improve vehicle localization performance on a map. It is shown that the proposed method can improve the estimated vehicle position on the map and suppress sensor misrecognition, especially when the external sensor's observation is within the evaluation horizon of MHE.
Nowadays, as the risk of the cyber-attack on vehicle systems increases, the needs for intrusion detection technology are increasing. In this paper, we proposed an integrated log intrusion detection method that is able to identify the intrusion level of attack chain. Furthermore, we evaluated the performance of the proposed intrusion system by deriving false positive rates using actual autonomous vehicle’s logs and attack coverage rates using CAPEC.