This paper describes the future outlook for transmission development activities. Increasing number of gears, further introduction of continuously variable transmission (CVT) and automated manual transmission (AMT), and improvement of element efficiency are expected to continue for reducing environmental impact, realizing easy shifting and smooth drive feel, and enhancing driving pleasure. Dual clutch transmission (DCT) should also increase for its easy shifting combined with smooth, direct drive feel. 4WD would see polarization into small, lightweight systems and those with high-performance, while hybrid systems would be narrowed down based on transmission efficiency and cost down.
The diesel engine is an attractive power source for automobiles when considering global warming and to save energy resources, due to the excellent thermal efficiency and performance. Technologies to reduce the exhaust gas emissions have been significantly improved and diesel vehicles have become recognized as ecologically responsible, but to clean the exhaust gas further, innovations are still needed to establish more reliable and lower cost technologies. This overview will detail developments and prospects for diesel engine technologies, including turbo-charging and EGR systems, common rail fuel injection systems, combustion technologies, after-treatment systems of the exhaust gas, and diesel hybrid systems.
After reviewing the history and status of Japanese ITS, the author shows that safe driving support systems do not spread into the market. Then the author suggests that one of the causes of this is to be developed by only natural scientists and engineers. Usually drivers have a kind of nonlinearity that is difficult for natural scientist or engineers to understand and there are some interactions between drivers and safe driving support systems developed by them. This interaction is not considered by natural scientists or engineers. In contrast with this social scientists are strong to study this interaction. The author, finally, points out the importance of the collaboration between social and natural scientists.
This paper reviews the status of Active Safety technology, as the research fields being provided into the vehicle research field, the road environment field, the driver research field and the evaluation methodology research field. Technical problems and future direction for solving the problems are proposed. Especially development of Driver Behavior model including cognitive and judgment process is introduced to be important item.
A micro-hole nozzle and an ultra-high injection pressure were employed to investigate the effects of the nozzle hole diameter and injection pressure on the spray, mixture formation, and combustion processes. The laser absorption-scattering (LAS) technique was adopted to obtain the qualitative and quantitative information on spray characteristics. A high-speed video camera system was employed to record auto-ignition and combustion processes. OH chemiluminescence was used as a marker of auto-ignition and as a measure of the flame lift-off length. The effects of injection parameters on auto-ignition and flame lift-off length were presented. The data on gas entrainment and fuel vaporization acquired in the evaporating sprays under the same ambient conditions were correlated to the auto-ignition process and flame lift-off length.
The effect of combining high pressure loop (HPL-) and low pressure loop (LPL-) EGR systems on engine performance and emission characteristics were investigated using a multi-cylinder diesel engine under steady-state conditions. At low load, increasing HPL-EGR rate causes higher soot emission whereas increasing LPL-EGR rate causes higher fuel penalty. To solve this problem, combining HPL- and LPL-EGR systems at low load can reduce exhaust emissions without fuel penalty. At high load, in contrast, since pumping loss is low effect on fuel consumption, increasing LPL-EGR rate with higher boost pressure can reduce NOx and soot emissions simultaneously.
Pin noise occurrence due to the impact of the piston pin against the pin boss bearing is one of the typical engine noises emitted from piston related regions. The detailed mechanism of the pin noise is not yet clearly understood. Contact force and acceleration generated in the around of the pin have been measured under the condition of engine operation and the mechanism of the phenomenon has been analyzed in detail.
The multi-ignition method using a small amount of diesel spray was tested to control the burning rate of the gasoline mixture. Results of experiments and numerical analyses indicate that combustion duration can be controlled by the injection timing and the spatial distribution of the diesel oil. Fast combustion can be achieved by widely distributing the diesel oil in the cylinder, and this method suppresses knock and improves thermal efficiency.
In the evaluation of durability, multi-body simulation using a tire model is expected to enable prediction of the forces generated on the vehicle when driving over rough roads. As the durability of a vehicle depends on generated forces, the accuracy with which such forces can be predicted by the simulation is a crucial factor in assessing it. This research was focused on a tire of low aspect ration for road load prediction. The accuracy of road load simulation on curb strike and rough road with applying a normal aspect ratio tire and a low aspect ration tire was evaluated by a full vehicle model developed in a multi-body simulation. The simulation results were compared with the measurements. By evaluating the results, it was confirmed that the low aspect ratio tire model evaluated in this research had an issue for the accuracy on longitudinal forces. The cause of this issue was considered by test and simulation of static load deflection of tire itself. It was considered that tire model could not reproduce enough non-linearity of tire near rim touching.
To study the unsteady aerodynamics of a vehicle body, a large-eddy-simulation of a transient turbulent flow around a simplified vehicle model subjected to a sudden crosswind is conducted. A numerical boundary model is introduced to simulate the entry into the crosswind and it successfully represents the situation. The numerical results show unsteady aerodynamic forces, especially a transitional drag force, acting on the vehicle body when the vehicle is initially subjected to crosswind. Furthermore, on the basis of visualizations of the numerical results, the mechanisms generating the transitional forces are discussed.
Drivers' properties to detect visual targets was investigated. White dot targets were presented on a screen, and both error rates and detection times were measured. The investigated factors affecting the detection were as follows: presentation type (appearance or changing size), target size, and background. In the results, more detection errors were observed for a small target presented far from the fixation point upon dot-texture background. The following factors increased the target detection times: presenting target in peripheral regions, lower rate of changing size, small size, and dot-texture background. "Detection maps" were illustrated to understand the drivers' visual detection properties intuitively.
In order to analyze the incident mechanism of traffic accidents, analysis was performed focusing on near-miss incident data in a vehicle-following situation. A feature of this data is that the headway time is shorter and that the reaction time is longer than normal braking in a vehicle-following situation. The analysis shows that traffic circumstances strongly influence driver behavior. Moreover, it also shows that the behavior of vehicles in an adjacent lane affect driving behavior as this might reduce situational awareness of the preceding vehicle, resulting in a shorter headway time.
We developed and proposed the extended friction model which can consider the instantaneous sliding vector and velocity dependency of friction coefficient as a linear damping effect. By definition of this model, line pressure and braking speed can be taken into account in the brake squeal simulation by using FEM. Also the tendency of brake squeal characteristics by deploying the extended friction model to Multi DOF is presented. Furthermore, the tendency of brake squeal characteristics by the adoption of partial shims that changes the contact pressure distribution is presented.
Traffic simulation is important technology for assessing the influence of traffic on the environment. It is also necessary to model driver behavior to evaluate the influence of new ITS services. In this paper, we describe a layered model which adds a physical car dynamics layer to the three-layer model of driver behavior and proposes a new distributed processing architecture to reduce the computational complexity using the space locality and time granularity of each layer.
NOx reduction mechanism and requirements for high NOx reduction efficiency in a urea SCR system at transient conditions with low exhaust gas temperature were investigated by using a four liters multi-cylinder diesel engine. NOx can be significantly reduced by adjusting mode-overall SCR inlet NO2/NOx ratio at 0.5±0.1 while adopting NH3 adsorption quantity control. It has been shown that ammonium nitrate (NH4NO3) plays an important role in enhancing the Fast SCR reaction at transient low exhaust gas temperature conditions.
The neutron diffraction method is an effective technique as a non-destructive evaluation for un inside residual stress of mechanical components. It is, however, difficult that is generally being used for stress measurement is applied to aluminum casting with large grain size. In this study, residual stress of inside aluminum casting was measured using an oscillation technique along with the neutron diffraction method to solve the problem. The measurement accuracy was quantitatively verified with shrinkage fitting specimen.
Due to visco-elastic properties of plastic materials, fatigue and creep life depends on load history. This dependency leads to low accuracy of life estimation by Miner rule which well explains fatigue life of metal materials. New life estimation method, was proposed, which takes visco-elastic properties into consideration. It is found that this method is effective for both fatigue and creep life estimation and well explains the dependency of life on load history.
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