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The Gasoline direct-injection (GDI) engine can emit high levels of particulate matter and unburned Hydrocarbons when operating under stratified charge combustion mode. Injecting late in the compression stroke means the fuel has insufficient time to atomise and evaporate. This could cause fuel film accumulation on the piston surface and combustion liner. Locally fuel rich diffusion combustion could also result in the formation of soot particles. Employing a split-injection strategy can help tackle these issues. The first injection is initiated early in the intake stroke and could ensure a global homogeneous charge. The second injection during the compression stroke could help form a fuel-rich charge in the vicinity of the spark plug. Many studies have established the crucial role that a split-injection strategy plays in the stratified charge operation of GDI engines.

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.

In today's highly competitive automotive markets manufacturers must provide high quality products to survive. Manufacturers can achieve higher levels of quality by changing or improving their manufacturing process and/or by product inspection where many strategies with different cost implications are often available. Cost of Quality (CoQ) reconciles the competing objectives of quality maximization and cost minimization and serves as a useful framework for comparing available manufacturing process and inspection alternatives. In this paper, an analytic CoQ framework is discussed and some key findings are demonstrated using a set of basic inspection strategy scenarios. A case of a welded automotive assembly is chosen to explore the CoQ tradeoffs in inspection strategy selection and the value of welding process improvement. In the assembly process, many individual components are welded in series and each weld is inspected for quality.

The ways in which vehicles are used in the field are continually becoming more diverse. In order to provide the optimum solution with respect to performance and weight, it is necessary to be able to assure vehicle endurance reliability with a high degree of accuracy in relation to the manner of use in each market. This situation has increased the importance of accurately quantifying the ways in which vehicles are used in the field and of designing vehicles with sufficient endurance reliability to match the usage requirements. This report presents a “market model” by which the manner of usage in the field can be treated quantitatively using combinations of environmental factors that influence the road load, drive load and corrosion load, representing typical loads vehicles must withstand.

The fuel energy consumption of subsonic air transportation is examined. The focus is on identification and quantification of fundamental engineering design tradeoffs which drive the design of subsonic tube and wing transport aircraft. The sensitivities of energy efficiency to recent and forecast technology developments are also examined.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

Achieving a multi-cylinder engine with excellent noise/vibration character sties and low friction at the main bearings requires an optimal design not only for the crankshaft construction but also for the bearing support system of the cylinder block. To accomplish that, it is necessary to understand crankshaft system behavior and the bearing load distribution for each of the main bearings. Crankshaft system behavior has traditionally been evaluated experimentally because of the difficulty in performing calculations to predict resonance behavior over the entire engine speed range. A coupled crankshaft-block analysis method has been developed to calculate crankshaft system behavior by treating vibration and lubrication in a systematic manner. This method has the feature that the coupled behavior of the crankshaft and the cylinder block is analyzed by means of main bearing lubrication calculations. This paper presents the results obtained with this method.

Recently, it has been very important to reduce the noise, especially the Squeak and Rattle noise, for improving customer appeal of passenger vehicles. The Squeak and Rattle noise occurring inside the car cabin during vehicle operation is an especially large problem. This paper describes a newly developed measurement technology that uses the developed signal processing using the Beam-forming method and vibration sensor to identify the Squeak and Rattle noise sources, making it possible to determine effective countermeasures quickly. This new technology is used to identify all Squeak and Rattle noises at a time among many different noises, for example Wind noise, Engine noise and Road noise occurring during vehicle operation, and is expected to shorten substantially the time needed for noise analysis and contribute to quality improvements.

This paper illustrates a methodology in which complete material-manufacturing process cases for closure panels, reinforcements, and assembly are modeled and compared in order to identify the preferred option for a lightweight closure design. First, process-based cost models are used to predict the cost of lightweighting the closure set of a sample midsized sports utility vehicle (SUV) via material and process substitution. Weight savings are then analyzed using a powertrain simulation to understand the impact of lightweighting on fuel economy. The results are evaluated in the context of production volume and total mass change.

In general, the improvement of vehicle body stiffness involves a trade-off with the body weight. The objective of this research is to derive the lightest-weight solution from the original vehicle model by finding the optimized spot-weld layout and body panel thickness, while keeping the body stiffness and number of spot welds constant. As the first step, a method of deriving the optimal layout of spot welds for maximizing body stiffness was developed by applying the topology optimization method. While this method is generally used in shape optimization of continuous solid structures, it was applied to discontinuous spot-weld positions in this work. As a result, the effect of the spot-weld layout on body stiffness was clarified. In the case of the body used for this research, body stiffness was improved by about 10% with respect to torsion and vertical and lateral bending.

NASA has long recognized the advantages of providing improved information interfaces to EVA astronauts and has pursued this goal through a number of development programs over the past decade. None of these activities or parallel efforts in industry and academia has so far resulted in the development of an operational system to replace or augment the current extravehicular mobility unit (EMU) Display and Controls Module (DCM) display and cuff checklist. Recent advances in display, communications, and information processing technologies offer exciting new opportunities for EVA information interfaces that can better serve the needs of a variety of NASA missions. Hamilton Sundstrand Space Systems International (HSSSI) has been collaborating with Simon Fraser University and others on the NASA Haughton Mars Project and with researchers at the Massachusetts Institute of Technology (MIT), Boeing, and Symbol Technologies in investigating these possibilities.

Car makers are working hard today to shorten development and production lead times through the use of flexibile manufacturing systems(FMSs)to meet diversified and individualized customer requirements. To achieve this goal, Nissan has been developing many kinds of new technologies and systems such as: (1) the intelligent body assembly system for body assembly processes; (2) a press die stamping simulation method and unified database for press die manufacturing; (3) a robot and facility teaching system using CAD data; (4) an automated assembly line for trim and chassis assembly operations. These new FMS methods have been implemented in many manufacturing areas, including the stamping shop, body assembly shop, painting shop and trim and chassis shop. This paper focuses mainly on the intelligent body assembly system as a typical example of the new production systems and technologies being developed at Nissan.

Eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. Considerable amount of research and development works have been done on the problem to date. In this study, we focused on the analyses of friction self-excited vibration and brake part resonance during high frequency brake squeal. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding velocities. Its vibration frequency can be calculated in relation to the mass and stiffness of the pad sliding surface. Frequency responses of the brake assembly were measured and the vibration modes of the pad, disc and caliper during squeal were identified through modal analysis. Further study led to the development of a computer simulation method for analyzing the vibration modes of brake parts. Analytical results obtained using the method agreed well with the corresponding experimental data.

The piston skirt is an important contributor of friction in the piston assembly. This paper discusses friction contributions from various aspects of the piston skirt. A brief study of piston skirt patterns is presented, with little gains being made by patterning the piston skirt coating. Next the roughness of the piston skirt coating is analyzed, and results show that reducing piston skirt roughness can have positive effects on friction reduction. Finally, an introductory study into the profile of the piston skirt is presented, with the outcome being that friction reduction is possible by optimizing the skirt profile.

Nissan has added ball bearings to its “High-flow Ceramic Turbocharger”(1) (introduced in 1987) to improve acceleration response by reducing friction loss. The following programs were carried out in applying ball bearings to the turbocharger: Optimum bearing size and material were selected to assure long life; lubrication techniques were employed to achieve compatibility between acceleration response and durability; a thrust support system was designed to assure that the ball bearings endure thrust load which varies in direction and magnitude during engine operation; and the squeeze film damper was optimized to keep the turbocharger silent. These innovations have resulted in a practical ball-bearing turbocharger, which has been installed in Nissan's most recent Skyline model(released in May 1989). This is the first time a ball-bearing turbocharger has been applied to a passenger car.

Use of high strength steel (HSS) could be an important consideration in achieving competitive weight and safety performance of the body-in-white (BIW). This study covers key technical issues in the application development. Many aspects were studied such as formability, weldability and impact strength for application of this grade to the BIW. One of the key issues is spot weldability, especially in the assembly of heavy gauge materials for structural parts. The spot weld strength appears not to satisfy the target for some HSS applications, when hardness of the nugget is high. The relation between weld strength and the chemical composition of steel sheets was studied, because hardness can be controlled by chemical composition and welding conditions. It was found that using lower carbon content or carbon equivalent compared to conventional grades could improve weld strength.

Painting is the most expensive unit operation in automobile manufacturing and the source of over 90 percent of the air, water and solid waste emissions at the assembly plant. While innovative paint technologies such as waterborne or powder paints can potentially improve plant environmental performance, implementing these technologies often requires major capital investment. A process-based technical cost model was developed for examining the environmental and economic implications of automotive painting at the unit operation level. The tradeoffs between potential environmental benefits and their relative costs are evaluated for current and new technologies.

Nissan is offering navigation systems in some domestic production models. These systems, which show drivers the vehicle's present location on a CRT map display, free them from anxiety about getting lost when traveling in an unfamiliar area. It is expected that future navigation systems will incorporate two key capabilities. One will be a route guidance capability, which will not only indicate the present location but also select the optimal route to the intended destination and guide drivers there by indicating which direction to take at each intersection along the way. The second capability will be a communications link with the roadside infrastructure for receiving outside information such as traffic congestion data and incorporating that information into route guidance. Nissan has established the core technologies of these navigation capabilities in the past ten years through the development of conceptual prototypes and experimental systems in government-sponsored projects.

The use of automatic transmissions is continually increasing because of their ease of operation. Transmission performance requirements that have become more important in recent years include smooth shift quality and a shift schedule that matches the driver's intentions. An electronically controlled automatic gearbox, which sets the shift schedule according to the vehicle speed and throttle valve opening, provides a dramatic improvement in shift quality over its hydraulically controlled counterpart. However, even with an electronically controlled automatic transmission, shift hunting occurs when driving uphill or towing an object Based on the use of fuzzy logic, a technique has been developed for estimating running resistance, represented by the road gradient. This technique has been incorporated in a new shift schedule control method that eliminates shin hunting Research is now under way on a fuzzy logic technique for inferring the driver's intention to accelerate

The thermal environment in the automotive engine compartment is expected to become increasingly severe in the years ahead owing to the installation of a large-size manifold catalyst to reduce exhaust emissions, among other factors. This will make it even more important to analyze the engine compartment layout in terms of heat flow considerations at the design conceptualization stage of a new vehicle. In this research, a flow analysis program called DRAG4D was applied to find the flow velocity distribution and ambient air temperature distribution in the engine compartment during driving, idling and after the engine was turned off. This original program developed at Nissan takes into account the effects of the energy balance and buoyancy, and provides a practical level of prediction accuracy. The time required to create an analytical model and perform the computations has been shortened by using an automatic grid generation function, based on a solid model, and experimental equations.