An algorithm to detect knock location was developed, utilizing differences in the arrival time of the pressure wave caused by knocking between 5 pressure sensors in the combustion chamber of a gasoline engine. In this algorithm, the time differences were derived from time-frequency analysis of the Fourier spectrum with an accuracy of several μs. Furthermore, calculation of knock location by the least square method correlated with the results of the experiment with minimum error. It was applied under certain conditions in a single cylinder engine, and knock locations were determined for both homogeneous and stratified combustion.

View full abstract

In this paper, it is shown that in a LPG liquid-phase injection engine, the pressure in a LPG fuel supply system should be controlled which lead to a fuel efficient engine system. Especially at a high output of injection fuel follow, the pressure is not necessarily controlled at high pressure. Thus the optimal pressure is determined experimentally and the experiments are followed to control the pressure at the lower optimal pressure for different outputs of the injection fuel follows for the different speeds of the engine. The fuel supply system without the return pipe exploited in our laboratory is used.

View full abstract

Hydrogen engines are required to provide high thermal efficiency and low nitrogen oxide (NOx) emissions. Direct-injection hydrogen engines have a potential to provide higher thermal efficiency and specific power rather than port-injection hydrogen engines. There are many possible combinations of injection pressure, injection timing and ignition timing that can be used in a direct-injection system for achieving such performance. In this study, different combinations of injection and ignition timings were classified as three combustion regimes, and experiments were conducted to make clear the differences in combustion conditions attributable to the operating conditions.

View full abstract

Correspondence to the seriousness of global environmental issues are required to the automobiles, as well as driving performances strongly required from the end-users. As a technology to improve both requirements, the variable valve actuation system, which controls valve events and lifts continuously, has been developed. This paper describes features of the system as well as the knowledge and test results obtained through the development of the system until it reaches the mass-production stage.

View full abstract

A steering system for μEV which characteristic is possible to be adjusted according to driver's characteristics is developed [1]-[3]. A planetary gear type active front-wheel steering system (ASS) can compensate for the delay and gain of the steering input. The system has also the torque assist/augmentation system (TAS) using torque split control of the in-wheel traction motors. The system characteristic is adjusted to the aged drivers and the effects of the system on the drivers are experimentally proved. It is confirmed that the characteristics of the driver change according to the steering characteristics as a result the system can compensate for deteriorated control ability. The torque augmentation control is also proved to be effective on improving on-center handling characteristics of the vehicle.

View full abstract

This paper proposes a rotary electric actuator for an active suspension system that controls movement in the roll, pitch, and bounce directions of the vehicle. The effect of sky-hook and inertia control on vehicle performance was then clarified. This paper also describes the effects of the actuator from standpoints of responsiveness and consumption energy of the active suspension system.

View full abstract

The authors have previously proposed a worm gear with a new tooth profile for use in electric power steering (EPS). Use of this new tooth profile enables a reduction in the diameter of the worm wheel.
This worm gear with its new tooth profile additionally provides increased transmission torque, reduced friction torque, and greater strength, thereby resolving basic issues that have previously affected conventional worm gears.
This paper describes the study of the worm wheel with the new tooth profile proposed by the authors that was conducted with a view toward enhancing transfer efficiency.
For this purpose, a meshing model for the worm gear was first created and used in order to examine the effects of the flexural rigidity of the worm wheel on transfer efficiency.
Next, worm wheels that actually have different flexural rigidity were fabricated. The transfer efficiency of the different worm wheels was studied in terms of their meshing area. The results revealed that there is a proper value for the flexural rigidity required to enhance transfer efficiency.

View full abstract

Cold-stamped door impact beams made of TS1180 MPa grade cold-rolled high strength steel have been developed. The newly developed parts achieved both weight and cost reductions compared to former hot-stamped parts. Cold-stamping was successfully performed by using a newly developed high strength steel sheet with high ductility. To avoid delayed fracture, conditions (applied stress, strain and hydrogen) in which hydrogen cracking of the steel occur were drawn up on a map and then applied conditions of the parts were set accordingly at safe levels far from the hydrogen cracking regions indicated on the map.

View full abstract

The accumulation behaviors of impurities in hydrogen for fuel cell vehicles were investigated by using a single cell test station equipped with a hydrogen circulation system. It was revealed that nitrogen and helium accumulate, but carbon monoxide, hydrogen sulfide and ammonia do not accumulate. Accumulation behaviors vary according to the different properties of impurities, such as adsorption properties, reactivity, water-solubility and gas permeability. The accumulation behaviors of each impurity found in the present study will be reflected in the formulation of a hydrogen quality standard for fuel cell vehicles.

View full abstract

Energy absorption performance of CFRP is determined by progressive fractures, and it is important to predict the occurrence of the initial fracture inside the ply and its relation with the final fracture mode. Therefore numerical calculations were performed considering a progressive fracture of each ply. In the progressive fracture model, fractures are classified into two kinds - fiber fractures and matrix fractures. When the fracture threshold is reached inside plies, the stiffness value is decreased.The progressive fracture model was applied to dynamic behavior for CAE and the occurrence of fractures and the load characteristics were examined, taking a beam subjected to bending load as an example. This study showed that calculation using the progressive fracture model matched the experimental results in the early stages with an example dynamic bending load.

View full abstract

Actual car test group and CAE (Computer Aided Engineering) group aims at completeness improvement of an initial drawing by high efficient and high-performance prediction technology toward development period shortening all in one body as the field of strength. In this report, an example that tried to promote high efficiency of the prediction technology of body panel stiffness is introduced by making full use of SQC (Statistical Quality Control) techniques such as Latin hyper-cubic method, response surface method, CAE and a support tool.

View full abstract

This paper compares evaluation indices for estimating driver risk perception of a rear-end collision. First, the definition and the characteristics are described briefly for each index. Second, relationships among the indices are theoretically discussed. Third, we compare time history characteristics in typical following situations by using numerical simulations. The indices were categorized into three groups in terms of required variables for calculation. The separation from the changes in which drivers do not decelerate at all was verified based on experiment data of typical vehicle-following situations acquired using a driving simulator.

View full abstract

A system is presented that recognizes risk level during driving based on images captured by an onboard camera. The developed system learns the relationship between image information and risk information derived from driver operation. This is as an evolutionary safety system that flexibly adapts to various drivers and environments by learning from driving experiences.

View full abstract

For active safety application, we developed a system that estimates the level of risk of traffic situations perceived by the driver, based on the driver's driving behavior. An interaction model between driving environment and operation is acquired by online learning, and driver-adapted results are output. This paper outlines the system algorithm and estimation experiment results.

View full abstract

We are developing a traffic simulator called STREET, which evaluate effectiveness to reduce accidents by safety systems. To evaluate safety systems, however, we have to be able to faithfully reproduce traffic accidents that are caused by interactive events between vehicles and between vehicles and pedestrians. In this method, we have constructed the driver model of normal driving behavior, and driver model which simulate driver's error in cognition, decision-making and operation. In this paper, we describe a method of reproducing traffic accidents. In addition, we talk about evaluating the ratio of accidents with/without active safety systems.

View full abstract

For the reduction of exhaust emissions of diesel engines, an improvement of a DI diesel engine system was carried out by using GTL fuel, which is expected as an alternative fuel. In this study, the combustion chamber, injection pattern and EGR calibration were modified utilizing combustion characteristics of GTL fuel. In addition, the after-treatment system for zero sulfur fuel was studied to realize a high conversion efficiency of NOx catalyst. As a result, the modified vehicle for GTL fuel realized J-SULEV regulation level emissions in vehicle test.

View full abstract

In this paper, we propose a stable vehicle ego-motion estimation method for monocular camera sensors. Vehicle ego-motion is the motion of a camera fixed to a vehicle. The 8-point-algorithm is well known as the typical method for obtaining camera motion, however, it outputs unreliable results in some cases. To obtain stable results, several methods have been proposed using a road surface constraint, however, there are difficult scenarios for these methods such as non-flat or non-textured roads. We solved these problems by using a constraint derived from vehicle motion.

View full abstract

A system that facilitates clutch and shift operation by electronic control actuators has been developed for motorcycles demanding high sports performance. A brief description of development of the "Yamaha Chip Controlled Shift" (YCC-S) automated manual transmission system for motorcycles that aspires to offer both high sports performance and comfort is provided herein.

View full abstract