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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.

In previous studies(1)(2), the acceleration performance of vehicles equipped with torque converter has been analysed with the assumption that the converter characteristic was under continued steady-state. However, in case of sharp acceleration of the fluid flow in the converter from inactive flow condition, which would occur at wide-open throttle starting, it is not possible to accurately analyse the vehicle performance at immediately after starting if the converter characteristic is assumed to remain under steady-state condition. In this paper, the transient phenomenon in the converter is verified by applying the theory of angular momentum and the concept of energy balance through the converter elements providing with a dynamic-model for the driveline. The present study has clarified the effect of the transient converter characteristic, at sharp starting, on the acceleration performance.

A stratified-charge lean-burn engine is newly developed for the purpose of energy saving and carbon dioxide reduction to minimize the global warming. The engine, named MVV(Mitsubishi Vertical Vortex)engine, is based on the unique vertical vortex technology which realizes stable combustion even with lean mixture without any additional device. And it also has another feature of “all range air-to-fuel ratio feedback control system” utilizing linear air-to-fuel ratio sensor. This paper describes various technologies developed in this engine.

In order to reduce exhaust emission and combustion noise and to improve fuel consumption, the effects of the combustion system parameters of a diesel engine, such as injection pressure, injection nozzle hole diameter, swirl ratio, and EGR rate on exhaust emissions, combustion noise and fuel consumption are investigated and described in detail by analyzing rate of heat release, needle valve lift and injection pressure. Based on these results, reduction of exhaust emission and combustion noise and improvement of fuel consumption are described in the latter part of this paper. These results are shown as follows. The smaller nozzle hole diameter is effective for reducing smoke and PM, and by optimizing the injection timing and swirl ratio, NOx can also be reduced. In addition to the above, by applying EGR and higher injection pressure it is possible to improve the fuel consumption with the remaining low NOx and PM.

Mitsubishi Motors Corporation succeeded in mass production of the electric vehicle “i-MiEV” which features leading-edge technologies epitomized by lithium-ion battery. The EV was released into the Japanese market in July 2009 and the European market in January 2011. In order to be used all over the world, the EV has to be practical and durable even under severe weather of extremely cold or extremely hot regions. In this paper we report some results of the tests conducted under extremely cold weather as well as extremely hot weather. From the test results the validity of the vehicle control system and the practicality of the EV are verified.

An analysis of the static behavior of T-shaped joint is presented. Advanced testings by laser holography and infrared ray stress wave analyzers verified the surface deformation and the stress concentration of joint area, which are very important factors of thin-walled joint stiffness. The definition of structural joint stiffness is attempted, and the relationship between structural joint stiffness and sizes(dimension) of the constructing members is obtained in case of a thin-walled T-shaped member with rectangular cross section. The parametric study to accomplish weight reduction, while maintaining the necessary structural joint stiffness, is described in case of Rocker to Center pillar. The numerical analysis of body structure considering the structural joint stiffness shows better accuracy as compared with the analysis with the joint assumed rigid.

Three Japanese automobile manufacturers-Mitsubishi Motors Corp., Nissan Motor Co., Ltd., and Toyo Kogyo Co., Ltd.-have been making efforts over the past three years to design and develop effective thermal reactor-exhaust gas recirculation and catalytic converter systems suitable for small engines. The work is being done by members participating in the IIEC (Inter-Industry Emission Control) Program, and the exhaust emission levels of the concept vehicles developed by these companies have met the goal established by the IIEC Program at low mileage. Each system, however, has a characteristic relationship between exhaust emission level and loss of fuel economy. Much investigation is required, particularly with respect to durability, before any system that will fully satisfy all service requirements can be completed. This paper reports the progress of research and development of the individual concept vehicles.

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.

In this study a new water injection system was applied to an 11 liter naturally aspirated DI diesel engine in order to reduce exhaust emissions. In this system, the water and fuel were arranged in the injection nozzle during the time between injections as fuel, water and then fuel. The fuel and water were then injected into the cylinder in that order. The tests were conducted at several engine operating conditions from the Japanese 13 mode test cycle to clarify effects of water injection on exhaust emissions and fuel consumption. The results showed that NOx reduction was directly proportional to the relative amount of water injection, regardless of engine speed and load. By using the optimal relative amount of water injection at each engine operating condition, total NOx and particulate matter (PM) in the Japanese 13 mode test cycle were reduced by 50% and 25%, respectively, without a fuel consumption penalty.

There have been various predictions made concerning the future profile for automobiles but such predictions have in many cases been based solely on anticipated advances in technology. In presenting a profile for automobiles in the year 2000, the writers predict the evolution and transfiguration of automobiles, taking both phases in the changing social environment and technical trends into account. Interest in automobiles is expected to shift from hardware to software and then to humanware (i.e. more emphasis is placed on the relationship with human beings), and automobiles will evolve and transfigure reflecting these changes.

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.

An efficient cooling system will ensure the reliability of the EV/HEV (Electric Vehicle/Hybrid Electric Vehicle) battery system and extend their lifetime. In order to shorten design period or increase design iterations, a high-speed and high-precision prediction method for cooling is indispensable. For models, such as Mitsubishi i-MiEV, which use fresh air to cool batteries in the battery pack, a transient approach based on loosely coupled method is developed to predict temperature change of batteries. The results by our new approach are in good agreement with the experimental data. Moreover, for the EV/HEV using circulated air to cool its batteries, a second approach is also developed, which can predict the temperature variations of both EV/HEV batteries in the battery pack and the cooling air.

This paper describes a method of predicting cooling performance in order to obtain the optimum design of the cooling system and front-end shape in the early stage of car development. This method consists of four calculation parts: thermal load on the cooling system, air flow through the engine compartment, heat dissipation by the heat exchangers and temperature distribution within the cooling system. It outputs the coolant, engine oil, automatic transmission fluid (A.T.F.) and charge air temperatures in exchange for the input of several car, power plant, drive train, exterior shape and cooling system specifications. For the calculations, in addition to theoretical formulas, several experimental formulas are introduced. This method verification is shown by presenting a few test cases for the respective calculation parts and the final solution.

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.

A new type of catalytic converter has been developed for the coming TLEV (Transitional Low Emission Vehicle) standards. It is a “Front Curve Catalytic Converter (FCCC)” using a curved cordierite ceramic honeycomb substrate. During this development, an optimum location and volume of the front curve catalytic converter were determined from the view points of thermal deterioration of the catalyst and hydrocarbon conversion performance. Based on CAE (Computer Aided Engineering) analysis, the best curvature radius of the substrate was selected to minimize a pressure drop of the front curve catalytic converter. The emission conversion and light-off performances of the front curve catalytic converter were compared with a conventional straight design. A series of durability tests; hot vibration, engine dynamometer and vehicle fleet tests were also conducted to confirm the reliability of the new front curve catalytic converter.

In the next few years, the USA, EU, and Japan plan to introduce very stringent exhaust emissions regulations for heavy–duty diesel engines, in order to enhance the protection air quality. This builds upon the heavy–duty diesel engine exhaust emissions regulations already in effect. At the same time, improvement in fuel consumption of heavy–duty diesel engines will be very important for lowering vehicle operating costs, conserving fossil fuel resources, and reduction of CO2 (greenhouse gas) levels. This paper presents a detailed review of a quiescent combustion system for a heavy–duty diesel engine, which offers breakthrough performance in terms of the exhaust emissions – fuel consumption trade–off, compared with the more conventional swirl supported combustion system. This conclusion is supported by experimental results comparing quiescent and swirl supported versions of various combustion system configurations.

In the heavy-duty commercial vehicle market in Japan, particularly in the segment of dump trucks and tractors, naturally aspirated engines maintain a dominant market share because of their superior torque characteristics in the low speed range. In order to meet the ever increasing needs for higher speeds of transportation, better fuel economy and higher reliability, and the needs for increasingly strict exhaust emission regulations, Mitsubishi Motors Corporation (MMC) has developed the 8M20, a 20 liter V8 diesel engine. The '92 model series of “THE GREAT”, MMC's main heavy-duty trucks, has featured this new and powerful engine and has been in the market place since October, 1991. The 8M20 is a naturally aspirated engine that provides an output of 294kW/2200rpm, complying with the current Japanese exhaust emission regulations.

A two-stage combustion is one of the Mitsubishi GDI™ technologies for a quick catalyst warm-up on a cold-start. However, when the combustion is continued for a long time, an increase in the fuel consumption is a considerable problem. To solve the problem, a stratified slight-lean combustion is newly introduced for utilization of catalysis. The stratified mixture with slightly lean overall air-fuel ratio is prepared by the late stage injection during the compression stroke. By optimizing an interval between the injection and the spark timing, the combustion simultaneously supplies substantial CO and surplus O2 to a catalyst while avoiding the soot generation and the fouling of a spark plug. The CO oxidation on the catalyst is utilized to reduce the cold-start emissions. Immediately after the cold-start, the catalyst is preheated for the minimum time to start the CO oxidation by using the two-stage combustion. Following that, the stratified slight-lean combustion is performed.

Mitsubishi Motors Corporation presents the newly-developed 2-liter engine, which we have named SIRIUS DASH. The SIRIUS DASH engine, with its compound intake system, features great performance in both high and low speed ranges while keeping fuel consumption low. The compound intake system operates the 3 valves in 2 stages. When engine speed is low, just one intake valve is used, but when engine speed increases, two intake valves are used. And to make this engine truly extraordinary, we added a turbocharger with an intercooler, and equipped the whole thing with a total electonic control system. Generally, high performance engines which have large inlet ports and high speed type valve timing enabling them to intake sufficient air for high performance at high speeds. The problem is here that when speed is dropped, combustion becomes unstable at the expense of torque and fuel consumption.

Injection rate control is an important capability of the ideal injection system of the future. However, in a conventional Common-Rail System (CRS) the injection pressure is constant throughout the injection period, resulting in a nearly rectangular injection rate shape and offering no control of the injection rate. Thus, in order to realize injection rate control with a CRS, a "Next- generation Common-Rail System (NCRS)" was conceptualized, designed, and fabricated. The NCRS has two common rails, for low- and high-pressure fuel, and switches the fuel pressure supplied to the injector from the low- to the high- pressure rail during the injection period, resulting in control over the injection rate shape. The effects of injection rate shape on exhaust emissions and fuel consumption were investigated by applying this NCRS to a single- cylinder research engine.