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Reducing the viscosity of a manual transmission oil is the most effective way to obtain a fuel economy effect with the lubricant. However, there are concerns that a lower viscosity may result in a thinner oil film, causing a decline in extreme pressure performance (anti-seizure and anti-wear performance) and anti-pitting performance at the high temperature condition. Therefore, a method for maintaining sufficient oil film thickness is needed for oils with reduced viscosity. In this study, attention was focused on the effects of the base oil and the viscosity index improver. As a result, a new manual transmission oil has been developed that provides an oil film thickness equal to that of current oil even though its viscosity has been reduced by half compared with the level of current oil. Specifically, the base oil is formulated with a high-viscosity mineral oil (Group I) and the molecular weight of the viscosity index improver has been reduced.

This paper presents a new material technology that can achieve both crashworthiness and weight reduction of the vehicle body. This new technology is based on three fundamental approaches. One is a technique for evaluating high-speed material deformation characteristics related to the crush behavior of energy-absorbing structures. A second is the material concept of high tensile steel featuring both increased material strength and higher strain-rate sensitivity in order to improve its energy-absorbing capacity. We have found 590N/mm2-class dual-phase (DP) steel consistent with this concept. The third is a technique for estimating the crush behavior of body structures, taking into account the plate thickness reduction and work hardening distribution resulting from the press-forming process. Finally, it was shown that the use of DP steel results in a 15% reduction in the weight of absorbing structures without affecting crashworthiness.

In a typical passenger car-to-pedestrian collision, it is noted that the pedestrian’s body rotates after the initial contact with the hood leading edge. Consequently, the head often crashes into a stiff part of the car body, resulting in serious or life-threatening head injuries. Therefore, to reduce pedestrian fatalities, it is important to improve vehicle structures so as to mitigate head injuries. Front fenders are one example of such stiff body parts with small impact energy absorption capability. This paper reports on the development of a new front fender structure designed to mitigate pedestrian head injuries in passenger car-to-pedestrian collisions. The new structure is characterized by fender supporting brackets that incorporate a break-off mechanism in the riveted joints between the fender and brackets.

This study investigated the mechanism by which a flat ride is perceived as low-frequency motion during highway driving. Vehicle motion was measured using a GPS receiver and an inertial navigation system. The driver’s head motion relative to the vehicle was measured with a motion capture system consisting of cameras attached to the vehicle. The results of an analysis showed that a flat ride could be quantified based on the amount of absolute head motion. Laboratory tests were also conducted to investigate the effects of motion in the visual field on the perception of ride comfort, and the results showed that perceptions of even the same motion varied depending on the visual conditions, such as the location of the hood, and such differences in motion perception affected the evaluation of a flat ride.

The load path U* analysis is an effective tool for investigating the load paths in body structures. In the present study, a new index U** is introduced to investigate structures under distributed loading. The new parameter U** is a complementary concept of U*. Although the conventional index U* cannot be applied to cases of distributed loading conditions, the new index U** can be applied to those cases. This paper describes the application of a load path U** analysis to improve efficiently the first eigenvalue of the vertical bending mode in a vehicle body structure model. It also explains how target parts for shape optimization are interpreted on the basis of a load path U** analysis when a load is applied to reproduce the first vertical bending mode.

This paper presents a study of antiknock performance under various octane numbers and compression ratios in a direct injection spark ignition (DISI) gasoline engine. The relationship between the octane number and engine performance in the DISI engine-the engine torque and the break specific fuel consumption (BSFC)-was investigated in comparison with a multipoint injection (MPI) engine. Due to the improvement in the charging efficiency and the advance of the ignition timing by cooled aspiration, the engine torque of the DISI engine was improved over that of the MPI engine. It was also found that the octane number requirement (ONR) was reduced. In addition, the possibility of engine performance enhancement at high compression ratios was studied. At high compression ratios, the engine torque is reduced due to the heavy knocking when low octane gasoline is used. However, an improvement in the engine torque has been observed with high octane gasoline.

Fuel cell vehicles (FCVs) are an emerging transportation technology, with a potential to provide very low vehicle emissions and significant improvements in fuel efficiency. The choice of a fuel for FCVs must consider several critical issues, including the availability of a distribution and storage infrastructure, manufacturing cost and capital requirements,energy efficiency, and performance. Gasoline, one of the candidate fuels, is noteworthy not only for its existing infrastructure, but because it has the possibility of usage for both FCVs and conventional internal combustion engines. Gasoline consists of different types of hydrocarbons, including paraffins, naphthens, olefins and aromatics - - with carbon numbers distributed over a wide range. Gasoline also contains a variety of sulfur compounds and selected additives in small amounts., In some cases gasoline also contains oxygenates such as MTBE and ethanol.

One promising solution for increasing vehicle fuel economy, while still maintaining long-range driving capability, is the plug-in hybrid electric vehicle (PHEV). A PHEV is a hybrid electric vehicle (HEV) whose rechargeable energy source can be recharged from an external power source, making it a combination of an electric vehicle and a traditional hybrid vehicle. A PHEV is capable of operating as an electric vehicle until the battery is almost depleted, at which point the on-board internal combustion engine turns on, and generates power to meet the vehicle demands. When the vehicle is not in use, the battery can be recharged from an external energy source, once again allowing electric driving. A series of models is presented which simulate various powertrain architectures of PHEVs. To objectively evaluate the effect of powertrain architecture on fuel economy, the models were run according to the latest test procedures and all fuel economy values were utility factor weighted.

On March 26, 2004, a fatal accident occurred when the head of a 6-year-old child was trapped in a large revolving door in a high-rise building in Tokyo. To investigate the cause of the accident, Prof. Yotaro Hatamura, representing Hatamura Institute for the Advancement of Technology, gathered experts in various fields including architecture and door manufacture, and initiated the “Door Project,” with the cooperation of the building company. Nissan Motor Co. participated in this project, and conducted load measurement tests on various doors. Applying car crash test technology, including production of special door test dummies and high-speed photography, it was possible to simulate the accident while taking human movement into account. As a result, we obtained important data for accident cause investigation.

This paper proposes an innovative and accurate method of estimating the internal conditions of rechargeable batteries for vehicles powered by electric motors, such as electric vehicles (EVs) and hybrid electric vehicles (HEVs). The proposed method is necessary to utilize battery power fully on vehicles powered by electric motors (especially HEVs) and thereby improve fuel economy or reduce the battery size. As the first step in this study, the relationship between the current and terminal voltage of a rechargeable lithium-ion battery was described using a linear parameter varying (LPV) model. That made it possible to reduce the problem of estimating the internal battery conditions (internal resistance, time constant, and so on) to a problem of recursively estimating the model parameters with an adaptive digital filter.

This paper proposes a new charge/discharge control system for hybrid electric vehicles based on the use of car navigation information. A conventional control system feeds back the battery state of charge (SOC) and controls the amount of charge/discharge to keep the battery SOC within a specified range. In contrast, the proposed control system is a predictive control system. According to information on the traffic conditions and road grade along the route suggested by the car navigation system, the system predicts the vehicle’s operating status, schedules the battery SOC along the route and controls the amount of charging/discharging. The effectiveness of the proposed system on improving fuel economy has been confirmed using actual traffic and road condition data.

This paper presents a new concept concerning engine mountings that can reduce engine booming noise by utilizing an additional vector. Booming noise in passenger cars, particularly those with a four-cylinder engine, is caused by exciting forces such as the second harmonic of engine intertial force. We have found that exciting forces transmitted from the engine to the body structure through the engine mountings are reduced by adding another vector which cancels out these exciting forces. This new vector can be obtained by using a mass-controlled region of a vibrating system possessing either a single degree or two degrees of freedom. When this optimally designed mechanism is adopted on a small passenger car, booming noise can be significantly reduced.

It is essential for today’s sports car to have excellent aerodynamic characteristics and a sophisticated style. These factors are dependent and often inconsistent with each other. It is desirable that they are integrated rather than compromised in such cases. In the early stages of development of the 280ZX, we thoroughly investigated the relationship between a style and its aerodynamic characteristics. A three-dimensional smoke tunnel and a 1/5-scale model was used for this purpose. Several improvements were examined mainly on the front end of the model, which strongly affect both aerodynamic characteristics and styling, such as the hood, bumper, chin spoiler, engine-compartment opening and others. The resultant values of the principal aerodynamic coefficients of the realized 280ZX are CD=0.385, CLF=0.11 and CYM=0.04 (CD and CLF at a yaw angle of 0 degree and CYM at 10 degrees).

A study of the deformation mechanism in head-on collision was conducted. A simple dynamic model of vehicle structure was assumed, and the model analyzed by using a high-speed computer; the solutions were then compared with the experimental results. Following are the findings obtained from the solutions: 1. In the case of a vehicle with independent rear suspension, the power train can provide much more resistance to the deformation as compared with a vehicle with conventional suspension. 2. The strength of front end structure has much effect on the deformation of passenger compartment.