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Following the previous reports, ventilation characteristics in automobile was investigated by using a half-scale car model which was created by the Society of Automotive Engineers of Japan (JSAE). In the present study, the ventilation mode of the cabin was foot mode which was the ventilation method for using in winter season. Supplied air was blown from the supply openings under the dashboard to the rear of the model via the driver's foot region in this mode. The experiment was performed in order to obtain accurate data about the airflow properties equipped with particle image velocimetry (PIV). Our experimental data is to be shared as a standard model to assess the environment within automobiles. The data is also for use in computational fluid dynamics (CFD) benchmark tests in the development of automobile air conditioning, which enables high accuracy prediction of the interior environment of automobiles.

This paper describes the calculative verification of the effect of the right-and-left torque vectoring system in various types of drivetrain, namely, the front wheels only, the rear wheels only, and both front and rear wheels in FWD, RWD, and AWD vehicles. The effect is evaluated by calculating the vehicle dynamics limit; maximum acceleration and cornering ability. The right-and-left vectoring torque, which is needed for expanding the vehicle dynamics limit, is also calculated. And finally, the paper evaluates the suitable wheels for which the system should be applied in each drivetrain. The application to the front wheels is more effective for FWD vehicles. On the other hand, the application to the rear wheels is more effective for RWD and AWD vehicles.

The purpose of this paper is to present a prediction method for the refrigerator performance of an automotive air conditioner (A/C). In order to predict the refrigerator performance in arbitrary situations, we consider the thermal equilibrium of the refrigeration cycle through A/C components, as the compressor, the evaporator and the condenser. These components are affected by the thermal property of the refrigerant. Influences of circumstantial flow and temperature field in the engine compartment also are reflected upon, because the cooling performance of the condenser is sensitive to that. In this paper, we try to derive algebraic models for the major components with regard to the thermal equilibrium in the refrigeration cycle. Furthermore, we use a Computational Fluid Dynamics analysis (CFD) for the prediction of cooling airflow temperature in the engine compartment, which is another essential factor in determining the state of the refrigeration cycle.

New numerical simulation system and experimental evaluation system has been developed to predict and evaluate occupant's thermal sensation in a passenger compartment in which environment is not steady and not uniform. Transitional effective temperature, which is new index of thermal sensation, is proposed and verified to correspond with subjects' thermal sensation votes. The simulation system has two advantage beside the prediction of thermal sensation; automatic generation of a computational model and coupling analysis of temperature including an analysis of temperature distribution inside a cabin, refrigerating cycle, solar radiation, and so on. It was verified that this system well predicts occupant's thermal sensation in a short time.

The 4M5 series of four-cylinder, in-line, direct-injection diesel engines has been released by Mitsubishi Motors Corporation for light and medium-duty trucks and buses. Featuring an updated structure and reflecting the employment of state-of-the-art technology in the design of every component, the new engine series offers high reliability and compact dimensions. Moreover, the new series well meets contemporary demands for high performance, low noise, and clean combustion.

Several different steel sheets were tested for energy absorption, using hat square columns and dynamic crash testing. Results indicate that steel sheets containing large volume fraction of retained austenite have relatively high energy absorption. The relationship between retained austenite and energy absorption was analyzed. These special steel sheets have already been successfully used for production body parts, such a front-side-member, without difficulties arising in volume production.

Austempered ductile iron (ADI) is a material having excellent mechanical properties and damping capacity. However practical mass production of ADI gears has not been possible due to ADI's poor machinability and distortion during the austempering heat treatment. With a new process method of carrying out hobbing before austempering when the material is in its soft condition, then austempering it and lastly, conducting the shave finishing process, we have diminished the above defects and developed practical ADI gears. These new gears generate less noise than ordinary nitrocarburized steel gears and are superior in pitting resistance.

Passenger cars with sunroofs sometimes experience a low frequency pulsation noise called “wind throb” when traveling with the roof open. This “wind throb” should be suppressed because it is an unpleasant noise which can adversely affect the acoustic environment inside a car. In this paper, 3-dimensional numerical flow analysis is applied around a car body to investigate the wind throb phenomenon. The computational scheme and the modeling method of the car body is first described. A flow visualization test in a water tunnel was completed for the simple car body shape to compare against the numerical procedure. The numerical and the visualized results compared well and the numerical simulation method employed was considered to be a reliable tool to analyze the wind throb phenomenon. Calculated results of pressure and vorticity distribution in the sunroof opening were analyzed with the spectrum of pressure fluctuation at the sunroof opening with and without a deflector.

When replacing a metal engine part with plastic, it is necessary to regard vibration damping as one of the important factors in terms of noise reduction as well as strength and heat resistance as being characteristics of the material. Plastics are far better for vibration damping than steel or aluminum, but this property is reduced by the addition of glassfiber-reinforced or high heat-resisting resins. We have taken notice of SMC (Sheet Molding Compound) which has the excellent strength and heat resistance properties and studied it in order to increase its vibration damping property. Since organic polymers show the peak value for vibration damping performance in the vicinity of the glass transition temperature (Tg), we studied a method to shift the Tg near the operating temperature region in order to improve the vibration damping property.

Since it is more difficult for truck door panels to realize curvature than passenger car door panels, internal stiffeners are mounted between the outer panel and inner panel through the use of an adhesive for ensuring stiffness. For this reason, a problem occurs as to the proper placement of the stiffeners so as to effectively improve stiffness. By FEM prediction and experimentation, the following have been clarified: (1) Arrangement of stiffeners for effectively improving stiffness (2) Stiffness share of stiffeners and outer panel against stiffness

We have developed a tappet with a cam lobe contacting tip made of a hard sintered material whose base material is cobalt, which adheres less to the steel of camshafts, and which also contains fine particles of tungsten carbide and chrome carbide. We have established a new evaluation method to access wear resistance performance of the tappet. It enables us to measure directly the friction force generated between the cam lobe and tappet and to evaluate anti-scuffing performance with high accuracy because we can clarify the time, load and cam angle at which scuffing occures.

We reported, in our first report1), the study of shapes of air deflectors that have strong yawing angle characteristics for the air resistance encountered when vehicles are running at high speed, taking into account the ambient wind. However, it is rarely the case that the optimum shape of air deflector, which was obtained and reported in our first report, is directly adopted for practical use. This paper reports the results of measurement tests on how the air resistance increases (worsens) when an air deflector is mounted on the cab of a vehicle: in the case when the air deflector was slightly changed on the same vehicle; or when the parameters of the vehicle (the height of the rear body) were changed for the same air deflector. We obtained the following results: Considerations and adjustments are required not to allow flows passing over upper and side surfaces of the air deflector to hit the front surface of the rear body.

Optimizing the design of automobile outer panels for weight reductions requires a consideration of stiffness and dent resistance. This paper presents a finite element analysis method for predicting the dent resistance of automobile body panels. The method is based on elastoplasticity analysis and nonlinear contact analysis. The analysis shows that dent resistance is greatly influenced not only by the stress-strain curve of the formed panel but also by the residual stress in the panel. An increase in yield stress improves dent resistance. The computed results obtained with this method compare favorably with experimental data, thereby validating this approach.

This paper presents a new torque distribution system-“Right/Left Torque Control System”, aimed at improving a vehicle's cornering properties by using yaw moment control. The torque transfer mechanisms of this system have been analyzed. Also, a yaw moment control algorithm using yaw rate feedback control has been designed. Next, vehicle cornering properties were evaluated using numerical simulation developed from data taken from an actual vehicle. As a result, improvements were achieved in the maneuverability and stability of a vehicle during cornering.

From the standpoint of safety, the demands are growing in recent years for better controllability and stability of automobiles and in particular in trucks. The truck, however, when compared with the passenger car, is subject to larger changes in gross vehicle mass and center of gravity depending on its load placement. In addition, since the cornering power generated by the truck tire per load is smaller than that generated by the passenger car tire, it is difficult to introduce significant improvements in controllability and stability simply by use of passive techniques like suspension characteristic tuning. Therefore, studies were performed on the applicability of the 4WS system, an active vehicle dynamic characteristic control technique, to a Truck as a means for solving these problems.

Aerodynamic drag reduction is one of the most important aspects of enhancing overall vehicle performance. Many car manufacturers have been working to establish drag reduction techniques. This paper describes the development process of a new small speciality car which achieved coefficient of drag(CD) of 0.25. A description of the test facilities and the systems used for developing the aerodynamic aspect of the car are also introduced briefly.

An investigation of anti-corrosion steel sheets (non-galvanized) which contain copper for automobile body parts has been conducted. Copper additives accelerate the formation of amorphous substrates. These substrates decrease the rate of corrosion. In order to retain the steel's formability and weldability, the contents of the alloying elements have been optimized. As a result, this newly developed steel sheet can be used for many different applications such as door sashes and door panels of mass produced cars. This paper describes the key properties of the newly developed steel sheet and additionally the mechanism of corrosion prevention, weldability, formability, and so on.

Flow and flame structure visualization and modeling were performed to clarify the characteristics of bulk flow, turbulence and mixing in a four-valve engine to adopt the lean combustion concept named “Barrel-Stratification” to the larger displacement center-spark four-valve engine. It was found that the partitions provided in the intake port and the tumble-control piston with a curved-top configuration were effective to enhance the lean combustion of such an engine. By these methods, the fuel distribution in the intake port and the in-cylinder bulk flow structure are optimized, so that the relatively rich mixture zone is arranged around the spark plug. The tumble-control piston also contributes to optimize the flow field structure after the distortion of tumble and to enable stable lean combustion.

This paper concerns driver's burden for visual information processing in which his central vision is coupled with his peripheral one. A visual driving simulator was applied to the first step of the study, where driver's responses to both central and peripheral tasks were simultaneously investigated. The series of test indicate that the driver's responsiveness to the central and peripheral tasks could define the whole burden for visual information processing. Therefore, it appears that the responsiveness to the peripheral vision could be more or less compromised to support the central one.

Recent global environmental problems which have come to light must be solved for ensuring the survival of the human race. And it is of the utmost importance that we give to our descendants a world full of nature and beauty. In the past years Mitsubishi Motors Corporation (MMC) has long been positive in research and the development activities so as to satisfy the demands for low emission and good fuel economy vehicles. (1) As one example of our research efforts, the technology that will meet the US '94 HDDE exhaust emission regulations, which is one of the most stringent regulations in the world, is described in this paper. The exhaust emissions were reduced by improvement of combustion, using the pre-stroke control type fuel injection pump and optimizing the combustion chamber shape. Efforts were also made to improve the oil consumption, in order to reduce PM (Particulate Matter) emission.