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The effects of spray/wall interaction on diesel combustion and soot formation in a two-dimensional piston cavity were studied with a high speed color video camera in a constant volume combustion vessel. The two-dimensional piston cavity was applied to generate the impinging spray flame. In the cavity, the flat surface which plays a role as the cylinder head has a 13.5 degree angle with the injector axis and the impinging point was located 30 mm away from the nozzle tip. Three injection pressures of 100, 150, and 200 MPa and a single hole diesel injector (hole diameter: 0.133mm) were selected. The flame structure and combustion process were examined by using the color luminosity images. Two-color pyrometry was used to measure the line-of sight soot temperature and concentration by using the R and B channels of the color images. The soot mass generated by impinging spray flame is higher than that of the free spray flame.

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.

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.

For a crash analysis using FEM with respect to a structure that is composed of thin plates, we developed a new structure study method (plastic strain equalization method). This method defines the optimality criteria as in the linear analysis of a fully stressed design and indirectly finds an optimal solution. We assume that a structure with both a lightweight and high collapse load should have sufficient strength corresponding to impact loads in each area. This means that at any area the load value and the strength are balanced at a certain value. For the criteria that the plastic strain value is equal over the whole area, a solution can be found by repeating computations. The design variable is the thickness of shell elements and the computation is iterated until plastic strain values are almost equal. In this paper, a structure with both a lightweight and a high collapse load could be optimized by equalizing the plastic strain value.

A technique to strengthen body frame with a polymeric structural foam has been developed with benefits of reducing vehicle weight and improving drivability and fuel economy. The idea of this new technology was evolved from the concept that body frame strength will increase drastically if the body frames are prevented from folding on collision. The energy of a collision impact would be effectively absorbed if weak portions of body frames are reinforced by a high strength structural foam. The new technology composed of the high strength structural foam and a light-weight frame structure with partial foam filling is reported here.

Aldehydes are the cause of sick house syndrome or chemical sensitivity and have harmful influences for human beings. In the cabin of vehicle, aldehydes which are included in the volatilization gas from the interior materials, DE emission gas in intake air, cigarette smoke and so on spoil the comfortableness. Active carbon, which has been used as an adsorbent, shows an excellent removal efficiency for most of the gas components by physical adsorption. But for aldehydes, it has difficulty because aldehydes are hard to be adsorbed physically. We have developed new aldehydes adsorbent undergoing addition reaction with gaseous aldehydes on its surface. Aldehydes capture material (ACM) make use of the chemical reaction using a resorcin as a reagent and an H-type zeolite as a water-containing support, and active hydrogen is used as a catalyst to promote the reaction. In addition, we have applied ACM to cabin air filter (CAF) of vehicle.

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.

Effects of split injection, with a relatively short time interval between the two sprays, on the spray development process, and the air entrainment into the spray, were investigated by using laser induced fluorescence and particle image velocimetry (LIF-PIV) techniques. The velocities of the spray and the ambient air were measured. The cumulative mass of the ambient air entrained into the spray was calculated by using the entrainment velocity normal to the spray boundary. The vortex structure of the spray, formed around the leading edge of the spray, showed a true rotating flow motion at low ambient pressures of 0.1 MPa, whereas at 0.4 MPa, it was not a true rotating flow, but a phenomenon of the small droplets separating from the leading edge of the spray and falling behind, due to air resistance. The development processes of the 2nd spray were considerably different from that of the 1st spray because the 2nd spray was injected into the flow fields formed by the 1st spray.

In order to study alternate methods of Air Fuel ratio (A/F) perturbation for maximizing three-way catalyst conversion efficiency, two methods for measuring the Oxygen Storage Capacity (OSC) of Catalyst were developed on an engine test bench. The first is to measure just the break-through Perturbing Oxygen Quantity (POQ, which is defined as the product of A/F amplitude, perturbation period and gas flow), and the second is to measure the response delay of the rear A/F sensor, which has been improved to be very similar to the former. Then, the OSC values of many catalysts were investigated with different perturbation parameters. The results show that OSC would not be affected by amplitude, period of perturbation and gas flow, and that the best conversion efficiency is obtained when the value of POQ is about 1/2 of the value for OSC. These results suggest that the best way to control perturbation is to keep POQ at 1/2 of OSC by setting perturbation parameters.

Mazda has developed new-generation V6 engines. The new V6 series comprises 2.5-litre, 2.0-litre and 1.8-litre engines. The development objective was to ensure high output performance for excellent “acceleration and top-end feel”, while satisfying “Clean & Economy” requirements. The engines also had to have a pleasant sound. Mazda selected for these engines a short stroke, 60° V-shaped 24 valve DOHC with an aluminum cylinder block. Various techniques are adopted as follows: Combustion improvement and optimization of control to achieve high fuel economy and low emissions Improvement of volumetric efficiency, inertia reduction of rotating parts and optimization of control to achieve excellent “acceleration and top-end feel” Adoption of a high-rigidity, two-piece cylinder block and crankshaft and weight reduction of reciprocating parts to achieve a pleasant engine sound Material changes and elimination of dead space to achieve a compact, lightweight engine

Lean-burn technology is now being reviewed again in view of demands for higher efficiency and cleanness in internal combustion engines. The improvement of combustion using in-cylinder gas flow control is the fundamental technology for establishing lean-burn technology, but the great increase in main combustion velocity due to intensifying of turbulence causes a deterioration in performance such as increase in heat loss and N0x. Thus, it is desirable to improve combustion stability while suppressing the increase in main burn velocity as much as possible (1). It is expected that the fluid characteristics of the in-cylinder tumbling motion that the generated vortices during intake stroke breake down in end-half of compression stroke will satisfy the above requisition. This study is concerned with the effects of enhancing of tumble intensity on combustion in 4-valve S. I. engines.

Cost and weight reduction considerations make it very important to evaluate and reduce aerodynamic noise in the early stage of vehicle develpment. For these reasons, a method to evaluate aerodynamic noise quantitatively is needed. As an initial step, our first paper investigated airflow around the A-pillar of a full-scale vehicle. As a result, vortical flow structure and the influence of the vortical flow on the pressure fluctuations were clarified. As the second step, this paper presents an estimation method for the aerodynamic noise from a vehicle. Based on Lighthill's equation, we propose an evaluation equation to estimate aerodynamic noise. The aerodynamic noise radiated externally from a vehicle is estimated as ∑(Pfi,fi,Sfi)2 Where Pfi is the fluctuating pressure on the surface of the vehicle, fi the frequency and Sfi the correlation area. The method is applied to the aerodynamic noise problem associated with the A-pillar of a vehicle.

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.

In this paper, a prediction method of the aerodynamic sound emitted from the three-dimensional delta wing of the attack angle at 15 degrees is presented. Computed flow Reynolds numbers range from 2.39x1 05 up to 9.56X 105. The method is based on the assumptions: flow Mach number is much less than unity and the strength of sound source equals Curle's dipole. These assumptions are validated by the experimental works performed in a quiet-flow-noise wind tunnel. Owing to the low Mach number condition, the computation region can be devided into two regions: inner flow region and outer wave region. The incompressible flow computation in the inner region is performed based on the full Navier-Stokes equations. The integration of the N-S equations are executed by using finite-difference method. For high Reynolds flow computation, the nonlinear convection terms are discretized by third-order upwind difference scheme.

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.

Mazda announced that all customers who purchase Mazda cars are provided with the joy of driving and excellent environmental and safety performance under slogan of "Sustainable Zoom-Zoom" long-term vision for technology development. The purpose of this study is to develop a new approach of Life Cycle Assessment (abbreviated to LCA) to be applied to clean energy vehicles and new car models. The improvement of both environmental performance, e.g., fuel consumption, exhaust emissions, vehicle weight reduction, and LCA that is a useful methodology to assess the environmental load of automobiles for their lifecycles has become more important. LCA by inventory analysis, for RX-8 Hydrogen RE as a rotary engine vehicle used hydrogen as clean energy, was carried out and disclosed the world for the first time. LCA for new Mazda 5 was carried out as the portfolio of all models, previously only the specific model equipped with fuel efficiency device based on ISO14040.

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.