Search Results

The adoption of the electronic controlled steering systems with new technologies has been extended in recent years. They have interactions with other complex vehicle subsystems and it is a hard task for the vehicle developer to find the best solution from huge number of the combination of parameter settings with track tests. In order to improve the efficiency of the steering system development, the authors had developed a steering bench test method for steering system using a Hardware-In-the-Loop Simulation (HILS). In the steering HILS system, vehicle dynamics simulation and the tie rod axial force calculation are required at the same time in the real-time simulation environment. The accuracy of the tie rod axial force calculation is one of the key factors to reproduce the vehicle driving condition. But the calculation cannot be realized by a commercial software for the vehicle dynamics simulation.

In this paper, we consider smart charging and vehicle-to-home (V2H) technologies for plugin electric vehicles coordinated with home energy management systems (HEMS) for automated demand response. In this system, plugin electric vehicles automatically react to demand response events with or without HEMS’s coordination, while vehicles are charged and discharged (i.e., V2H) in appropriate time slots by taking into account demand response events, time-ofuse rate information, and users’ vehicle usage plan. We introduce three approaches on home energy management: centralized energy control, distributed energy control, and coordinated energy control. We implemented smart charging and V2H systems by employing two sets of standardized communication protocols: one using OpenADR 2.0b, SEP 2.0, and SAE standards and the other using OpenADR 2.0b, ECHONET Lite, and ISO/IEC 15118.

In 2006, Nissan began limited leasing of the X-TRAIL FCV equipped with their in-house developed Fuel Cell (FC) stack. Since then, the FC stack has been improved in cost, size, durability and cold start-up capability with the aim of promoting full-scale commercialization of FCVs. However, reduction of cost and size has remained a significant challenge because limited mass transport through the membrane electrode assembly (MEA) has made it difficult to increase the rated current density of the FC. Furthermore, it has been difficult to reduce the variety of FC stack components due to the complex stack configuration. In this study, improvements have been achieved mainly by adopting an advanced MEA to overcome these difficulties. First, the adoption of a new MEA and separators has improved mass transport through the MEA for increased rated current density. Second, an integrated molded frame (IMF) has been adopted as the MEA support.

This paper presents a modeling method for prediction of low-frequency road noise in a steady-state condition where rotating tires are excited by actual road profile undulation input. The proposed finite element (FE) tire model contains not only additional geometric stiffness related to inflation pressure and axle load but also Coriolis force and centrifugal force effects caused by tire rotation for precise road noise simulation. Road inputs act on the nodes of each rib in the contact patch of the stationary tire model and move along them at the driving velocity. The nodes are enforced to displace in frequency domain based on the measured road profile. Tire model accuracy was confirmed by the spindle forces on the rotating chassis drum up to 100Hz where Coriolis force effect should be considered. Full vehicle simulation results showed good agreement with the vibration measurement of front/rear suspension at two driving velocities.

This paper proposes a novel method of verifying comprehensive driver model used for the evaluation of driving safety systems, which is achieved by coupling the traffic simulation and the driving simulator (DS). The method consists of three-step procedure. In the first step, an actual driver operates a DS vehicle in the traffic flow controlled by the traffic simulation. Then in the next step, the actual driver is replaced by a driver model and the surrounding vehicle maneuvers are replayed using the recorded data from the first step. Then, the maneuver by the driver model is compared directly with the actual driver's maneuver along the simulation time steps.

Cold weather operation has been a major issue for fuel cell hybrid vehicles (FCHV). To counteract the effects of low temperatures on FCHV operation, an approach for rapid warm-up operation based on concentration overvoltage increase and conversion efficiency decrease by limiting oxygen or hydrogen supply was adopted. In order to suppress increases in exhaust hydrogen concentration due to pumping hydrogen during rapid warm-up, dilution control using bypass air and reduction of concentration overvoltage by a minimum voltage guard were implemented. These approaches effectively control waste heat generation and suppress exhaust hydrogen concentrations during cold start and warm-up. These developments were incorporated into the 2008 Toyota FCHV-adv and it was confirmed that the rapid warm-up operation strategy allowed the FCHV-adv to be successfully and repeatedly started at -30°C.

A robotic driver has been designed on the basis of an analysis of a human driver's action in following a given driving schedule. The self-learning algorithm enables the robot to learn the vehicle characteristics without human intervention. Based on learned relationships, the robotic driver can determine an appropriate accelerator position and execute other operations through sophisticated calculations using the future scheduled vehicle speed and vehicle characteristics data. Compensation is also provided to minimize vehicle speed error. The robotic driver can reproduce the same types of exhaust emission and fuel economy data obtained with human drivers with good repeatability. It doesn't require long preparation time. Thereby making it possible to reduce experimentation work in the vehicle development process while providing good accuracy and reliability.

A number of active safety systems are already developed to support drivers’ decision and action to help avoid accidents, but further enhancement of those active safety systems cannot be accomplished without increasing our understanding on driver behaviors and their interaction with vehicle systems. For this reason, a state-of-art driving simulator (DS) has been developed that creates very realistic scenarios as a means of realizing these requirements. The DS consists of a simulator cabin, turntable (inside the dome), a 6-DOF hexapod system, shakers (vehicle vertical vibration actuators), and a motion system capable of moving 35 meters longitudinally and 20 meters laterally. The system is also capable of projecting images of actual city streets and highways onto a 360° spherical screen inside of the dome. As a result, the DS is able to reproduce a driving environment that is very similar to real driving.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

To improve the fuel economy via high EGR, combustion stability is enhanced through the addition of hydrogen, with its high flame-speed in air-fuel mixture. So, in order to realize on-board hydrogen production we developed a fuel reformer which produces hydrogen rich gas. One of the main issues of the reformer engine is the effects of reformate gas components on combustion performance. To clarify the effect of reformate gas contents on combustion stability, chemical kinetic simulations and single-cylinder engine test, in which hydrogen, CO, methane and simulated gas were added to intake air, were executed. And it is confirmed that hydrogen additive rate is dominant on high EGR combustion. The other issue to realize the fuel reformer was the catalyst deterioration. Catalyst reforming and exposure test were carried out to understand the influence of actual exhaust gas on the catalyst performance.

Recently, global warming and energy security have received significant attention. Thus an improvement of the vehicle fuel economy is strongly required. For engines, one effective way is to improve the engine thermal efficiency. Raising compression ratio [1] or turbo charging technologies have potential to achieve high thermal efficiency. However knock does not allow the high thermal efficiency. Knock depends on the fuel composition and the pressure and temperature history of unburnt end-gas [2-3]. For fuels, RON is well known for describing the anti knock quality. High RON fuels have high anti knock quality and result in higher thermal efficiency. This paper investigates the impact of high RON fuels on the thermal efficiency by using high compression ratio engine, turbo charged engine, and lean boosted engine [4]. Finally, it is shown that the high thermal efficiency can be approached with high RON gasoline and ethanol.

Reduction of exhaust emissions was investigated in a modern diesel engine equipped with advanced diesel after treatment system using a Gas-to-Liquid (GTL) fuel, a cleaner burning alternative diesel fuel. This fuel has near zero sulfur and aromatics and high cetane number. Some specially prepared GTL fuel samples were used to study the effects of GTL fuel distillation characteristics on exhaust emissions before engine modification. Test results indicated that distillation range of GTL fuels has a significant impact on engine out PM. High cetane number also improved HC and CO emissions, while these fuel properties have little effect on NOx emissions. From these results, it was found that low distillation range and high cetane number GTL fuel can provide a favorable potential in NOx/PM emissions trade-off. In order to improve the tail-pipe emissions in the latest diesel engine system, the engine modifications were carried out for the most favorable GTL fuel sample.

Feasibility studies concerning ethanol utilization in direct injection gasoline engines were conducted in order to clarify the effects of ethanol on engine performance, exhaust emissions and injector deposit formation. The investigation results indicate that E100 (100% ethanol fuel) can improve full load engine performance around whole engine speed range in a high compression ratio engine (ε=13:1), compared to that of a base compression ratio engine (ε=11.5:1) operated on a premium gasoline. This was caused by the volumetric efficiency (ηv) improvement and engine knock suppression in the high compression ratio engine. On the other hand, HC emissions remarkably increased under lower engine speeds at a full load condition. This phenomenon suggests that poor combustion occurred due to insufficient mixing of air and E100 fuel under these conditions, in which the amount of ethanol injected was too large and fluidity in the cylinder was weak.

From the viewpoint of primary energy diversification and CO2 reduction, interests of using Biomass Fuel are rising. Some kinds of FAME (Fatty Acid Methyl Ester), which are obtained from oil fats like vegetable oil using transesterification reaction with methanol, are getting Palm Oilpular for bio-diesel recently. In this study, we have conducted many experiments of palm oil hydrogenations using our pilot plants, and checked the reactivity and the pattern of product yields. As a result, we figured out that the hydrocarbon oil equivalent to the conventional diesel fuel can be obtained from vegetable oils in good yield under mild hydrogenation conditions. Moreover, as a result of various evaluations for the hydrogenated palm oil (oxidation stability, lowtemperature flow property, LCA, etc.), we found that the hydrogenated palm oil by our technology has performances almost equivalent to conventional diesel fuel.

From the energy security and CO2 discharge reduction point of view, much attention has been paid to the usage of biofuel, ethanol, as an alternative source of energy in the transportation industry. Yet, the major drawback in applying highly concentrated ethanol in the spark ignited internal combustion engines is cold start instability. This is due to the characteristics of ethanol, large latent heat required to vaporize. This paper investigates necessary conditions for the engine cold start, using highly concentrated ethanol. Tests performed with varieties of ethanol fuel, a relationship between cold startability lower temperature limit and reid vapor pressure was observed. A method to boost the vaporization, intake valve timing control is introduced to obtain high compression peak temperature.

This paper describes a headway distance control system for platoon driving on an automated highway system (AHS). The system implemented on a test vehicle is described first, followed by a description of a vehicle control method based on the use of throttle and brake actuators. This method makes it possible to obtain the target acceleration and deceleration regardless of the vehicle speed range and the rate of acceleration or deceleration. Experimental and simulation results obtained with this method are presented. A control method is then described that uses inter-vehicle communication and laser radar to maintain a constant headway between vehicles. The results of simulations and driving tests conducted with three vehicles are presented to illustrate that the use of inter-vehicle communication is highly effective in improving headway control performance.

In order to determine the main factors causing the mileage-related increase in formaldehyde emission from methanol-fueled vehicles, mileage was accumulated on three types of vehicle, each of which had a different air-fuel calibration system. From exhaust emission data obtained during and after the mileage accumulation, it was found that lean burn operation resulted in by far the highest formaldehyde emission increase. An investigation into the reason for the rise in engine-out formaldehyde emission revealed that deposits in the combustion chamber emanating from the lubricating oil promotes formaldehyde formation. Furthermore it was learnt that an increase in engine-out NOx emissions promotes partial oxidation of unburned methanol in the catalyst, leading to a significant increase in catalyst-out formaldehyde emission.

With the support of Horiba and Horiba STEC, Toyota Motor Corporation has developed an exhaust emissions simulator to verify the accuracy of extremely low emissions measurement systems. It can reliably verify the accuracy (correlation) of each SULEV emission measurement system to within 5% under actual conditions. The simulator's method of simulating SULEV gasoline engine cold-start emissions is to inject bottled gases with known concentrations of each emission constituent to the base gas, which is clean exhaust gas from a SULEV vehicle with new fully warmed catalysts. First, the frequencies and dynamic ranges of the SULEV cold-start emissions were analyzed and the method of 2 injecting the bottled gases was considered based on the results of that analysis. A high level of repeatability and accuracy was attained for all injection flow ranges in the SULEV cold-start emission simulation by switching between high-response digital Mass Flow Controllers (MFCs) of different full scales.

The durability test with road-load input is necessary for evaluating durability of body and chassis structure in automotive applications. This paper shows the method to analyze road-load input to a suspension system for development of a simple component level bench test. This method enables the extraction of the essential inputs to evaluate the durability of suspension parts using the transfer function (frequency response function) measured by Multi-axial Road Simulator and wheel force transducers. These extracted inputs contribute to development of a new realistic component bench test.

Increasing expectations for stability at high speed call for the improvement of cars' aerodynamic performance, in particular lift reduction. However, due to styling constraints, traditional spoilers must be avoided and replaced by other solutions like underfloor components. Flow simulation is expected to be a useful tool for lift prediction, but the conventional models used so far did not represent complex geometry details such as the engine compartment and underfloor, and accuracy was insufficient. In the present study, a full vehicle simulation model, including the engine compartment and underfloor details, was used. Other improvements were also made such as optimization of the computational grid and the setting of boundary conditions for reproducing wind tunnel experiments or actual driving, making it possible to predict lift variations due to vehicle geometry changes.