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This study simulates soot formation processes in diesel combustion using a large eddy simulation (LES) model, based on a one-equation subgrid turbulent kinetic energy model. This approach was implemented in the KIVA4 code, and used to model diesel spray combustion within a constant volume chamber. The combustion model uses a direct integration approach with a fast explicit ordinary differential equation (ODE) solver, and is additionally parallelized using OpenMP. The soot mass production within each computation cell was determined using a phenomenological soot formation model developed by Waseda University. This model was combined with the LES code mentioned above, and included the following important steps: particle inception during which acenaphthylene (A2R5) grows irreversibly to form soot; surface growth with driven by reactions with C2H2; surface oxidation by OH radical and O2 attack; and particle coagulation.

Owing to the small size of engines and high injection pressures, it is difficult to avoid the fuel spray impingement on the combustion cylinder wall and piston head in Direct Injection Spark Ignition (DISI) engine, which is a possible source of hydrocarbons and soot emission. As a result, the droplets size and distribution are significantly important to evaluate the atomization and predict the impingement behaviors, such as stick, spread or splash. However, the microscopic behaviors of droplets are seldom reported due to the high density of small droplets, especially under high pressure conditions. In order to solve this problem, a “spray slicer” was designed to cut the spray before impingement as a sheet one to observe the droplets clearly. The experiment was performed in a constant volume chamber under non-evaporation condition, and a mini-sac injector with single hole was used.

Lateral distance from the center of a driver's seating position to the gas and brake pedals is one of the main design factors that relates to the ease of stepping on the pedals from one and the other. It is important to keep a certain distance between the pedals to prevent erroneous operations or to reduce the driver's anxiety. In this paper, we explain that the distance between the pedals is affected by the driver's seating height. In other words, if the driver sits lower, the accuracy of stepping on the pedals from the gas pedal to the brake pedal will increase compared to the higher seating position. In addition, we found out that providing auxiliary parts for the leg support enhances the accuracy of the pedal operations.

We have proposed a human mimetic machine, using electronics control technology, which is quasi-human like an android equipped with volition as a new technical concept for man-machine systems. This machine determines the driver's physiological and psychological conditions and, in response, controls surrounding stimuli, such as sounds and vibrations. In this way, the relationship between the driver and the vehicle is made more human like. To determine the significance of the human mimetic machine, we have been developing a biofeedback vigilance control system, which maintains an optimum vigilance level during driving by controlling stimuli. In the first stage of the study, we have developed an accurate method to determine vigilance level using multiple regression analysis of electroencephalograms.

An Advanced driving simulator has been developed at Mazda Yokohama Research Center. The primary use of this simulator is to research future driver-vehicle systems. In an emergency situation, a driver must respond rapidly to perceived motion and visual stimulus to avoid an accident. In such cases, because the time delay associated with the perception of motion cues is shorter than visual and auditory cues, the driver will strongly rely upon perceived motion to control the vehicle. Hence, a driving simulator to be used in the research of driver-vehicle interactions in emergency driving must include a high performance motion system capable of large amplitude lateral motion. The Mazda simulator produces motion cues in four degrees of freedom, provides visual and auditory cues, and generates control feel on the steering wheel. This paper describes the merit of the large amplitude motion system and the features of this newly developed driving simulator.

This paper describes a calculating method to predict the quasi-static collapsing behaviors of spot-welded closed-hat section curved beams under axial compression. The overall deformat ions and the local buckling modes of beams were calculated using a geometrical model. Force-displacement relations were predicted by a elastic-plastic structural analysis method using the ‘plastic hinge’ concept. Collapsing tests were made on beams which are differenting section size, rotation angle, and metal sheet thickness. Comparisons between the calculated and experimental results of deformed shapes of beams, the local buckling modes and the force displacement relations are discussed.

Spot friction welding (SFW) is a cost-effective spot joining technology for aluminum sheets compared with resistance spot welding (RSW) [1]. In this study, coated mild steel was spot friction welded to 6000 series aluminum using a tool with shoulder diameter of 10 mm and welding conditions of 1500-2000 rpm and time of 5 s. Testing showed that tensile shear strength increased as the solidus temperature of the coating on the steel decreased. Microstructure characterizations of steel/Al joint interfaces showed that zinc from the coatings was incorporated into the stir nuggets and that intermetallic phases may have formed but not in continuous layers. Some Al-Zn oxides that appeared to be amorphous were also found in the joint interfaces.

In recent years, improving fuel efficiency and collision safety are important issue. We have worked on a new construction method to develop body structure which is light weight and strong/stiff. We adopt multi type Tailor-Welded Blanks (TWB) which is formed after welding several steel sheets for ATENZA (MAZDA 6), NEW DEMIO (MAZDA 2), and RX-8. This is a technology to consistently improve of such product properties and to reduce costs. Laser welding is a common TWB welding method, but for further equipment cost reductions and productivity improvements, we have developed a higher welding speed and robust plasma welding and introduced this to mass production. We introduce this activity and results in this report.

As a demand for vehicles of higher functionality grows, automakers and material suppliers are devoting increasing efforts to develop technologies for greater safety, lighter weight, higher corrosion resistance, and enhanced quietness. The resin-sandwiched vibration damping steel sheet (VDSS), developed as a highly functional material for reducing vehicle vibration and noise, has been used for oil pans1) and compartment partitions2). First applied for a structural dash panel of the new Mazda 929, a Zn-Ni electroplated VDSS which allows direct electric welding has contributed to greater weight reduction as well as improved quietness.

The thermal fluid field in a vehicle cabin model is analyzed by the mesh free method as well as mentioned in the Part 1. This paper focuses on the steady state indoor climate in the vehicle cabin including the effect of the buoyancy, the heat generation of the driver and heat conduction through the vehicle body surface under the maximum air-cooling condition soaked in a climate chamber in the summer condition for the demonstration of the mesh free method without not only the deformation of the 3D-CAD model but mesh generation. The solar radiation distribution and heat generation through the exhaust pipe from the engine room are simply included in the analysis. Simulated results are compared with experiments in the conditions of both moving and idling states. As a result, no significant difference in air temperature between simulation and experiments can be obtained in both conditions.

In previous Life Cycle Assessment (LCA) methods, environmental burden items to be analyzed, prior to a life cycle inventory analysis, were assumed as the main factors of environmental problems regardless of the product category. Next, the life cycle inventory analysis, in which the total amount of environmental burden items emitted during the life cycle of a product was calculated, and an environmental impact assessment were performed. The environmental impact assessment was based on the initially assumed environmental burden items. The process, in other words, was a particular solution based on this assumption. A general solution unconstrained by this assumption was necessary. The purpose of this study was to develop a general method of LCA that did not require such initially assumed environmental burden items, and to make it possible to perform a comprehensive environmental impact assessment and strategically reduce environmental burden of a product.

First, this paper describes a measurement of the human back-backrest interface contours and a reduction procedure of the measured contours to reconstruct the statistical back contours of American 50 and 95-percentile male. Second, the paper illustrates the difference of the back contour between the statistical male drivers and SAE 3-D Manikin. Finally, the advantage of using the back contour model in experiment is given. The AM 50 back contour model was used as a loader to obtain the backrest pressure distribution and proved an excellent tool for backrest comfort evaluation.

A method was studied for simultaneous zinc phosphating on aluminum and steel surfaces to obtain high corrosion resistance on aluminum surfaces, which conventional phosphatic processing could not provide with sufficient corrosion resistance. Since aluminum is protected by an oxide film on its surface, it has poor processability with zinc phosphating solutions applied to steel. An appropriate quantity of fluoride was therefore added to improve processing, and the coating film, aluminum composition and surface conditions were optimized to suppress filiform corrosion, which is characterized by string-like blisters of paint film starting from a paint defect. In addition, in view of the actual production environment, the corrosion resistance of the ground area made for readjustment after stamping was studied for the optimization of the processing solution.

In order to investigate the corrosion resistance of organic composite-coated steel sheets ( OCS ) in a real automotive environment, many kinds of corrosion tests were performed on test pieces and real automotive doors. Tests with a corrosive solution including iron rust were introduced to simulate the real corrosive environment of automotive doors. The relationship between the components of OCS and the corrosion resistance in the rust-including tests was examined. In addition, electrochemical studies were performed. Results indicate OCS has much better corrosion resistance than plated steel sheets with heavier coating weight in all tests. OCS shows excellent corrosion resistance in rust-free corrosive solution, however, some types of OCS do have corrosion concerns in rust-including tests. It became clear that these OCS types have an organic coating with lower cross-linking.

Mazda established an original design methodology combining a capacitive coupling technology and transmission line theory, to develop a high performance window antenna for AM/FM radios which construction is very simple to construct and requires no use of any antenna boosters or matching circuits. This paper introduces the design methodology and performance characteristics of the new antenna as well as its application to the production '95 model Mazda 929.

The present trend of internal combustion engines toward higher-speed and higher-output capacity is pressing the need for improved lubrication of sliding parts in the combustion chamber to secure reliability. To meet this need, investigation into frictional phenomena was made with a rotary engine, which led to the development of a method of coating the inner surface of the rotor housing with fluorocarbon resin superior in self-lubrication and friction resistance. Rotary engines given this surface finishing showed no trace of irregular wear of the sliding surfaces even when subjected, prior to completion of run-in firing (in green condition), to high-speed and high-load tests, indicating this method's noteworthy benefit of improving comformability. This method offers an excellent surface finish for sliding parts of internal combustion engines (rotary and reciprocating) which will gain increasingly higher output in the future.

A new process for manufacturing high-strength gears has been developed to meet the requirement of automobile transmission miniaturization. The points of the process are to increase the shot peening intensity and to perform optimal control of the initial (before shot peening) microstructure by heat treatment corresponding with the peening intensity in order to obtain higher residual compressive stress. The new process, named Carbonitriding and Hard Shot Peening in Mazda, brings a much higher fatigue strength than the one obtained by the conventional carburizing and shot peening process.

To coat flexible parts such as R-RIM Urethane Fascia baked at low temperatures, a different painting approach from one for steel parts is employed. Since paint color differences between the fascia and the body would downgrade the product, a color matching technique is required. For better color matching, matching of color shades was attempted with improvement of paint resin, optimal pigment blending and analysis of how color is affected by varying conditions. Application of a primer for finishing has brought about the desired paint film distinctness. Introduced was also the high weatherablilty paint for plastic parts. All such techniques were utilized on R-RIM Urethane Fascia to achieve high-grade color matching.