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Existing stop-start systems have several concerns such as take-off response, engine restart noise, high cost and system complexity. This paper describes a newly developed stop-start system that overcomes these concerns and can be used on high-volume production models at an affordable cost. The new system is based on a compact motor generator that allows cranking at restart and also functions as an alternator following engine start. A belt-driven system is used for restarting the engine to avoid noise from gear insertion and engagement. The motor generator is capable of high-speed operation for reducing engine startup time. Starting control has also been improved to achieve the shortest possible startup time in combination with a newly developed direct injection engine. Shortening the startup time tends to impair engine smoothness at restart. However, this concern has been resolved through cooperative control with the motor generator.

This paper presents advanced and cost-reducing technologies of a motor drive system with reduced permanent magnets but without a position sensor. The key enabler is the integration of novel designs of flux-intensifying interior permanent magnet synchronous machines (FI-IPMSMs) and position self-sensing control technologies. In this paper, we focus on two advantages of FI-IPMSM over conventional flux-weakening interior permanent magnet synchronous machines (FW-IPMSMs). The first benefit is that thinner magnets are possible and there is less concern for demagnetization because of its significantly smaller flux-weakening current. This paper presents two design examples of FI-IPMSMs, one of which has not only smaller magnets but also similar power conversion capability. The second advantage is reduced saturation and cross-saturation effect, which leads to improved position self-sensing capability.

This paper describes a vision-based vehicle detection system for a blind spot warning function. This detection system has been designed to provide ample performance as a driving safety support system, while streamlining the image processing algorithm so that it can be processed using the computational power of an existing ECU. The procedure used by the system to detect a vehicle in a blind spot is as follows. The system consists of four functional components: obstacle detection, velocity estimation, vertical edge detection, and final classification. In obstacle detection, a predicted image is generated under the assumption that the road surface is a perfectly flat plane, and then an object is detected based on a histogram that is created by comparing the predicted image and an actually observed image. The velocity of the object is estimated by tracking the histogram over time, assuming that both the object and the host vehicle are traveling in the same direction.

A hybrid system that has been put on the market by Nissan Motor Company was configured by removing the torque convertor with a lockup clutch from a conventional 7-speed automatic transmission and installing a clutch and a motor in its place. This hybrid electric vehicle (HEV) has a simple structure and is expected to improve fuel economy and responsiveness because it eliminates the torque convertor. One issue for this system is that an abrupt change in the input torque could cause torsional vibration of the drive shaft, resulting in a severe degradation of ride comfort. To solve this problem, an original vibration control system that was adapted for the mass-produced LEAF electric vehicle was also adapted for use on this HEV fitted with an engine and a 7-speed automatic transmission. This control system enables the hybrid vehicle to generate maximum motor torque at launch and also provides significant advantages for vehicle design.

From the March/Micra released in 2002 to the LEAF EV today, on-board electronic systems have come to possess bigger software programs and more complexity in the transition to distributed high-speed ECU network systems. Meanwhile, faster time-to-market requirements have shortened the development period. If a conventional development process like the waterfall model is applied to develop a distributed ECU network system, numerous problems may occur at the vehicle testing stage that requires a lot of rework. To avoid that, we devised a new development methodology of distributed ECU systems and implemented it in our vehicle function development programs to improve development work quality across the entire spectrum of vehicle electronics. This development methodology consists of two principal elements. One is an Electronic Integration Platform (EIPF) and the other one is a Design-EIPF (D-EIPF).

Various technologies for improving the environmental performance of vehicles have been vigorously developed in the automotive industry in recent years. In this regard, the core technologies for improving vehicle fuel economy are still mostly aimed at internal combustion engines. This paper presents a new variable displacement oil pump (VDOP) that was adopted for enhancing the fuel economy of a newly developed 1.2-liter three-cylinder supercharged gasoline direct injection engine. It describes the purpose, benefits, performance and variable displacement principle of the VDOP. Published papers concerning the development of the new engine, the friction reduction technologies it embodies and additional details of the mechanisms incorporated in the new oil pump are cited in the references for the further information of the reader.

A new transparent resin material developed by uniformly dispersing a nano-filler (boehmite particles, 5 nm in diameter and 197 nm long) in polycarbonate resin combines a flexural modulus of 5.9 GPa, a linear expansion coefficient of 35 ppm/K, and excellent mechanical toughness with excellent optical characteristics (transparency with 1.1% haze at 1 mm thick). These characteristics make this material highly suitable as a replacement for automotive glass that allows innovative design, a liberating sense of openness for automobiles.

This paper describes the design, fabrication and evaluation of a TDMA (time division multiple access) passive wireless torque sensor using 2.45 GHz surface acoustic wave (SAW) delay lines. The SAW torque sensor consists of a sensor element fabricated on a LiNbO₃ substrate and a support element. The sensor element is a strain-detection thin substrate, on which an interdigital transducer (IDT) and reflectors are fabricated. The support element converts torque force to strain that changes geometrical dimensions of the sensor element. Torque measurement was successfully demonstrated in a torque range of -1000~1000 Nm under static condition. The influence of rotation on wireless transmission of the sensor was also investigated. On condition that a shaft with the sensor was rotated step by step, we found that wireless communication was successfully demonstrated using two flexible antennas and a power divider.

The requirements of suspension systems have become increasingly complex in recent years due to the expansion of global markets and diversification of the conditions under which vehicles are used in different parts of the world. It is also becoming increasingly important to ensure that vehicles offer the secure handling stability which are expected by drivers, but can also provide an adequate level of ride comfort when driving on a wide diversity of road surfaces in all parts of the world. From an environmental viewpoint, it is also essential to achieve weight reductions for better fuel economy. To meet these wide-ranging requirements, we have developed a new multi-link rear suspension that has a simple link configuration and a lower link that features a connecting bushing mechanism developed by Nissan.

This paper describes a newly developed hydraulic variable valve timing control (VTC) system, targeting the internal combustion gasoline engine, with an optimum angular position locking mechanism to reduce tailpipe emissions (TPE). In general, emission control catalysts are used as one measure to reduce TPE. However, there is the issue that catalysts cannot remove pollutants before reaching its light-off temperature at cold engine start. To address this issue, we have been using a method of increasing the valve overlap period between intake valve opening (IVO) and exhaust valve closing (EVC) by operating a VTC system at engine start. This brings engine-out emissions (EOE) back to the combustion chamber to be burned, thereby reducing EOE levels. However, this method requires about 3 seconds for the sufficient hydraulic pressure to start VTC operations.

This paper describes a new 1.2-liter three cylinder gasoline engine named HR12DDR, with the target to achieve the lowest level CO2 in the European B-segment market and also, to satisfy the customer's driving pleasure through high output performance. This engine is developed with the consideration of meeting further strict regulations in the years ahead and of the possibility of being an alternative powertrain of diesel in the future as well. As a first step this engine was applied on the European Nissan Micra in 2011; achieving 95g/km CO2 emissions(NEDC mode). This low fuel consumption was realized mainly through technologies which scope to maximize thermal efficiency with high compression ratio, and to minimize the mechanical friction loss. The combustion was optimized by Direct injection (DI)system. To obtain the better fuel economy performance without sacrificing high output, we chose the supercharger system with bypass valve and electromagnetic clutch.

This paper describes the design measures taken to develop the noise and vibration performance of a new rear suspension and a new drivetrain system for rear-wheel-drive vehicles. The new rear suspension is designed to solve trade-off issues between road noise and handling performance. Despite higher drive torque, booming noise is greatly reduced by the new rear suspension and drivetrain without increasing the vehicle weight or sacrificing fuel economy.

This paper describes a functionality and test results of moving object detection based on vision system. Moving object detection is realized by just adding image processing software to the vision system with no additional sensor. Moreover, by usage of around view monitor system as vision system, existence of moving objects surrounding the subject vehicle can be informed to support the driver in the parking maneuver.

Hybrid powertrain technology, which combines an internal combustion engine and an electric motor as power sources, is penetrating auto markets as a practical approach for reducing vehicle fuel consumption and exhaust emissions. This paper describes the development of an integrated powertrain simulation technology for predicting the fuel economy and exhaust emissions of hybrid electric vehicles with high accuracy and computation speed. Primary paths of kinetic, electric, chemical and thermal energies and their management were modeled. The predicted exhaust emissions and temperatures of the coolant and lubrication oil agreed well with experimental data in various vehicle driving conditions. This simulation was used to study an air-fuel ratio control strategy for reducing NOx at engine restart and to examine an exhaust heat recovery method for reducing fuel consumption and exhaust emissions under cold start conditions.

Nissan have developed a new powertrain for the electric vehicle, and have installed it in the Nissan LEAF. In order to achieve an improved driving range, power performance and dynamic performance, Nissan have adapted a high efficiency synchronous motor, a water-cooled inverter, and passive-cooled laminated Li-ion battery. Especially Nissan has been emphasizing electric powered technology with a focus on advanced lithium ion battery from 1992. This presentation will introduce the features of Nissan LEAF and its battery technologies.

Stress induced by an excessive difference in pressure between the air and the hydrogen in polymer electrolyte fuel cells degrades membrane durability. Controlling such stress improves the durability and solves one of the problems hampering commercialization of fuel cell electric vehicles. Hydrogen pressure can be raised more rapidly than the air pressure by regulating the pressure of the high-pressure hydrogen storage tank. However, the response for reducing the hydrogen pressure varies depending on the level of current generation. The air pressure can be reduced rapidly by releasing air, whereas it takes longer to raise the air pressure owing to compression of the air taken in from the atmosphere.

Recently, urgent needs have arisen for improving the fuel economy of passenger cars. To improve the fuel comsumption, it is necessary to develop a technology that can improve fuel efficiency and weight-saving. This paper describes the development of a soundproof package to balance weight-saving with performance of acoustic isolation used to reduce engine noise. First, we developed a hybrid statistical energy analysis (HSEA) model to evaluate the performance. Second, by using the HSEA model, we (1) analyzed the power flow and dominant path from noise source to interior cavity, (2) extracted efficient sections such as dash, dash penetration parts, and floor so as to improve the performance. Using the above process, we developed a soundproof package that improves the performance without increasing the weight. As a result, we balanced weight-saving with performance of acoustic isolation using the HSEA model.

A new 1.2L inline 3-cylinder supercharged gasoline engine was developed to improve fuel efficiency and to meet EURO 5 emission regulations. The engine was designed with a high compression ratio, heavy exhaust gas recirculation (EGR), and a long stroke to improve fuel efficiency. The Miller cycle and a direct fuel injection system were applied to this engine in order to mitigate the occurrence of knock due to the high compression ratio. In addition, a supercharging system was adopted to compensate for the decline in charging efficiency due to the Miller cycle. The design of a direct injection gasoline engine involves a lot of problems such as reduction of oil dilution, stabilization of combustion at first idle retarded, improvement of air-fuel mixing homogeneity, and strengthening of the gas flow. It is hard to resolve these problems independently due to their complexities and difficult nature. Reducing wall wetting by the fuel spray can improve oil dilution in a small engine.

The fuel economy benefits of Continuously Variable Transmission (CVT) technology have led to a steady growth in their adoption since the 1990's that is likely to continue despite the competition from Dual Clutch Transmission (DCT) & Automated Manual Transmission (AMT) technology. Even though CVTs provide a smoother driving experience due to their “shift-free” operation, general market feedback indicates some level of consumer dissatisfaction in the area of acceleration sound quality. This is particularly evident in the sub-compact and compact vehicle segments that feature small four cylinder engines with cost/weight limited sound packaging. The dissatisfaction with the acceleration sound quality is primarily linked to the non-linear relationship between engine RPM and vehicle speed that is inherent to CVTs and is often referred to as “rubber-band” feel.