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This paper presents the results of a strength analysis of a newly developed steel structure featuring a special cross section achieved with the hydroforming process that minimizes the influence of springback. This structure has been developed in pursuit of further weight reductions for the steel body in white. A steel tube with tensile strength of 590 MPa was fabricated in a low-pressure hydroforming operation, resulting in thicker side walls. The results of a three-point bending test showed that the bending strength of the new steel structure with thicker side walls was substantially increased. A finite element crush analysis based on the results of a forming analysis was shown to be effective in predicting the strength of the structure, including the effect of work hardening.

This paper presents a vehicle dynamic simulation using a finite element method for performing more accurate simulations under extreme operating conditions with large tire deformation. A new hourglass control scheme implemented in an explicit finite element analysis code LS-DYNA(1) is used to stabilize tire deformation. The tires and suspension systems are fully modeled using finite elements and are connected to a rigid body that represents the whole vehicle body as well as the engine, drive train system and all other interior parts. This model is used to perform cornering and braking behavior simulations and the results are compared with experimental data. In the cornering behavior simulation, the calculated lateral acceleration and yaw rate at the vehicle's center of gravity agree well with the experimental results. Their nonlinear behavior is also well expressed.

To reduce quenching distortion, step gas quenching has been proposed in recent years, which refers to rapid gas cooling of steel from austenitizing temperature to a point above or below Ms temperature, where it is held for a specific period of time, followed by gas cooling. In this study, by using infrared thermography combined with conventional thermocouple, a new temperature monitoring and control system was developed to realize the step gas quenching process of a hypoid ring gear after low pressure carburizing. The test production results indicate that by using the new monitoring and control system, we can control the gas quenching process and the distortion of carburized gear treated by step gas quenching can be reduced significantly compared with standard gas quenching.

The SKY Project (Start ITS from Kanagawa, Yokohama) was launched in October 2004 in Yokohama, Japan in order to contribute to the local community by reducing traffic accidents and congestion. SKY is a private sector collaboration between Nissan Motor Co., Ltd., NTT DoCoMo, Inc., Panasonic Corporation, and Xanavi Informatics Corporation (now Clarion Ltd.). Support has also been provided from the public sector, namely the National Police Agency of Japan (NPA) and the Kanagawa Prefectural Police. Through the use of in-vehicle technology and an Intelligent Transportation Systems (ITS) that communicates with the infrastructure, information on nearby vehicles and the surrounding traffic environment can be utilized to reduce traffic accidents, shorten travel times, and increase fuel savings. These are the goals of the SKY project. This paper shows the results of early stage testing and the introduction of newly started trials.

This paper describes the development of a vehicle with four-wheel steering in which the rear wheels can be controlled electronically in addition to the conventional front-wheel steering system. In the method for steering the rear wheels, the side-slip angle at the vehicle's center of gravity is maintained at zero, which improves the basic dynamic properties of the vehicle. This approach allows greater maneuverability at low speed by means of counter-phase rear steering and improved stability at high speed through same-phase rear steering. However, the use of counter-phase rear steering to improve maneuverability gives rise to problems in regard to practicality. In addition, continuously controlled four-wheel steering, using counter-phase at low speed and same-phase at high speed, leads to many other problems regarding practicality because of the strong apparent understeer characteristics.

The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.

Nissan has developed a second generation ceramic turbocharger rotor which provides greater reliability and higher performance than a conventional ceramic rotor. The new rotor is made of silicon nitride, which has demonstrated sufficient strength in vehicle applications. The bonding technique for joining the ceramic rotor to the metal shaft has been confirmed through experimentation to have sufficient reliability. The second generation rotor is featured by the low stress design and higher dynamic strength, and two factors contribute to its higher reliability. The rotor shape was optimized on the basis of results obtained in two analyses of particle impact resistance and applied combined stress. Test results show that the reliability of the second generation rotor have been substantially improved over those of the conventional rotor now being used on production vehicles.

Electric Vehicle distinctive techniques in order to enhance the vehicle dynamic performance have been studied and applied to Nissan LEAF. From the viewpoint of performance design parameters, this paper introduces the application items focusing on effectuality for the vehicle behavior by means of the yawing motion and the rolling motion control of its vehicle. As the result, the effects of vehicle performance are shown in experimental data.

This paper reports about a trial for miniaturization of an air-cooled inverter integrated with motor, which is realized by reduction of the total volume of smoothing capacitor. An integrated system prototype was constructed with a disk-shaped inverter positioned at the rear end of the motor. We examined the possibility of using a ceramic capacitor, which features a higher heat-resistance temperature, lower internal resistance and higher capacity density than a film capacitor. At the same level of capacitance, the volume of a ceramic capacitor is less than one-half that of a film capacitor, enabling the size of the smoothing capacitor to be reduced to approximately one-fifth that of the currently used device. A suitable circuit configuration and physical layout of distributed smoothing capacitors and corresponding power device modules are proposed and demonstrated.

Nissan’s variable compression turbo (VC-Turbo) engine has a multilink mechanism that continuously adjusts the top and bottom dead centers of the piston to change the compression ratio and achieve both fuel economy and high power performance. Increasing the exhaust gas recirculation (EGR) rate is an effective way to further reduce the fuel consumption, although this increases the exhaust gas condensation in the cylinder bores, causing a more corrosive environment. When the EGR rate is increased in a VC-Turbo engine, the combined effect of piston sliding and exhaust gas condensation at the top dead center accelerates the corrosive wear of the thermal spray coating. Stainless steel coating is used to improve the corrosion resistance, but the adhesion strength between the coating and the cylinder bores is reduced.

This paper presents the technologies incorporated in an electric vehicle (EV)/hybrid electric vehicle (HEV) inverter built with power semiconductors of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) instead of conventional silicon (Si) insulated gate bipolar transistors (IGBTs). A SiC inverter prototype of 2.9 L in size for driving an 80-kW motor was fabricated and evaluated on a motor test bench. The SiC inverter prototype attained average efficiency of 98.5% in the Worldwide harmonized Light-duty Test Cycle (WLTC) driving mode. The two main technologies achieved with this SiC inverter prototype are described. The first one is a new direct-cooled power module with a thick copper (Cu) heat spreader located under the semiconductors that improves thermal resistance by 34% compared with a conventional direct-cooled power module.

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.

This paper describes the plastic body panels developed for the Nissan Be-1 which was released and put on sale in Japan in January 1987. The panels include four body parts: left and right front fenders, front apron and rear apron. They are made of a thermoplastic resin and are produced by injection molding. The top paint coat can be sprayed on all four panels simultaneously with other steel body panels. The panels provide a high-quality appearance that is in no way inferior to the paint quality of steel panels. This is true during initial use as well as over long periods of time. Besides providing weight reductions, they also deliver improved resistance to impacts. CAE process was applied to develop these panels and proved to be quite effective.

Internal combustion engines experience severe valve train wear and the reduction of valve seat and seat insert wear has been a long-standing issue. In this work, worn valve seats and inserts were examined to obtain a fundamental understanding of the wear mechanisms and the results were applied in developing new valve seat insert materials. The new exhaust valve insert material for gasoline engines is a sintered alloy steel containing Co-base hard particles, with lead infiltrated only for inserts used in unleaded gasoline engines. The new intake valve insert material for gasoline engines is a high-Mo sintered steel, obtained through transient liquid phase sintering and with copper precipitated uniformly. This material can be used for both leaded and unleaded gasoline engines. Valve and valve seat insert wear has long been an issue of concern to engine designers and manufacturers.

A CVT variator chain system is superior in transmission efficiency to a belt system because of its lower internal friction. However, a chain produces more noise than a belt due to the long pitch length of contact between the pulleys and rocker pins. This study focuses on optimization of the pitch sequence for reducing chain noise. The previous pitch sequence was suitably combined of links of different lengths to improve noise dispersibility for reducing chain noise. First, the object function was defined as the reduction of the peak level of 1st-order chain noise combined with a well-balanced the levels on the low and high frequency sides. Interior background noise consisting of road noise and wind noise have the characteristic that they increase as the frequency decreases.

A copper alloy powder composed of Cu-14Ni-3Si-2V-2Cr-1.5Fe-1Al-0.5P has been developed for application to laser-clad valve seats. Laser-clad valve seats offer several advantages such as higher engine output and improved fuel economy owing to lower valve head temperature and an increased intake throat diameter compared with conventional press-fit valve inserts made of ferro-based powder metal. Previously, a material having a principal chemical composition of Cu-12Ni-10Co-3Si-2V-2Nb-1.5Fe-1Al was developed to obtain large hard intermetallic compounds. The microstructure of this material is formed by a two-liquid separation reaction, which has been applied to powders of different chemical compositions for laser-clad valve seats of production engines. Although this material shows superior valve seat wear resistance, it has certain drawbacks, including the high cost of the powder, high probability of microcrack formation and low machinability of the laser-clad layer.

A linear-shaped module based on Si-Ge alloys has been made for thermoelectric generation. The module is designed for generating electricity by exhaust heat of, e.g., plants, furnaces or automobiles. The module consists of 9 couples of p- and n-type Si-Ge alloy-based thermoelectric semiconductors. Carbon layers are made on both sides of the p- and n-type elements, and then the elements are electrically connected in series using Mo electrodes by blazing method. The size of the module is approximately 3.5 mm in width, 70 mm in length and 9.3 mm in height. Maximum power of the module was 2.0 W at a temperature difference of 509 K between the hot and cold sides of the module. A variation of generating power was measured for 150 modules. Maximum power of every module-block consisting of 10 modules was evaluated at a temperature difference of 400 K. The maximum power of the module-blocks was varied from 6.9 W to 8.7 W.

A prototype navigation system with cellular phone access to an information service center was constructed and evaluated. Center personnel can also operate the system remotely, in addition to providing traffic information and information for more enjoyable travel. Real-time conversation with a center operator is also possible. The system was rated positively by most of the subjects, especially the real-time voice service. This paper describes the car navigation market and cellular phone market in Japan, the system configuration, evaluation results and possible solutions to problems in the system. It also touches on the outlook for future car navigation systems and information services.

This paper discusses the influence of variations in the vehicle deceleration curve on dummy injury criteria for a passive seat belt-restrained dummy using MVMA-2D crash victim simulation and sled tests for frontal crash analysis. The MVMA-2D simulation and sled tests verified that the vehicle deceleration curve exhibiting the higher Residual Deformation (RD) produces smaller dummy injury criteria. Also, using MVMA-2D simulation, the peak levels of the first and second waves were changed as parameters to ensure accurate evaluation of the influence of the deceleration curve on dummy injury criteria. Moreover, this paper also discusses Nissan's use of both occupant kinematic simulation and vehicle structural sisulation for frontal crash in the development of its vehicles.

This paper describes a control method to improve straight-line stability without sacrificing natural steering feel, utilizing a newly developed steering system controlling the steering force and the wheel angle independently. It cancels drifting by a road cant and suppresses the yaw angle induced by road surface irregularities or a side wind. Therefore drivers can keep the car straight with such a little steering input adjustment, thus reducing the driver's workload greatly. In this control method, a camera mounted behind the windshield recognizes the forward lane and calculate the discrepancy between the vehicle direction and the driving lane. This method has been applied to the test car, and the reduction of the driver's workload was confirmed. This paper presents an outline of the method and describes its advantages.