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Combustion and exhaust emission characteristics were compared among three representative diesel fuels called “Base (corresponding to a Japanese market fuel)”, “Improved” and Swedish “Class-1” using both a modern small and an optically accessible single-cylinder DI diesel engines. In these tests, the relative amount of PM collected in the exhaust was “Base” >“Class-1” >“Improved” at almost all of the operating conditions. This means that “Class-1” generated more PM than “Improved”, even though “Class-1” has significantly lower distillation temperatures, aromatic content, sulfur, and density compared with “Improved”. There was little difference in combustion characteristics such as heat release rate pattern, mixture formation and flame development processes between these two fuels. However, it was found that “Class-1” contained more branches in the paraffin fraction and more naphthenes.

This paper describes the development of alloy cast iron that can be used for the cutting edges of the trimming die of a press die. Usually, a block of tool steel or steel casting is inserted at the cutting edge of the trimming die of a press die. However, we unified the structure part and the cutting-edge part of a press die with alloy cast iron. As it can''t bear as the cutting edge in this state, the cutting edge is processed by flame-hardening. After the flame- hardening, we developed the alloy cast iron so that enough hardness may be obtained by natural air cooling. Thereby, the machining of the installation seat of the cutting edge decreased and the expense of dies has been reduced.

The potential of high efficiency zero-emission engines fueled by hydrogen, which is regarded as a promising form of energy for the future, is being researched. The argon circulated hydrogen engine [ 1 ] is one system theoretically capable of achieving both high efficiency and zero emissions, and its feasibility for use in vehicles has been studied. Specifically, tests were performed to verify the following issues. It was examined whether stable hydrogen combustion could be achieved under an atmosphere of argon and oxygen, which has a high specific heat ratio, and whether the substantial thermal efficiency improvement effect of the argon working gas could be achieved. An argon circulation system was also studied whereby steam, which is the combustion product of the hydrogen and oxygen emitted from the engine, is separated by condensation to enable the remaining argon to be re-used.

Premixed diesel combustion modes including low temperature combustion and MK combustion are expected to realize smokeless and low NOx emissions. As ignition must be delayed until after the end of fuel injection to establish these combustion modes, methods for active ignition control are being actively pursued. It is reported that alcohols including methanol and ethanol strongly inhibit low temperature oxidation in HCCI combustion offering the possibility to control ignition with alcohol induction. In this research improvement of diesel combustion and emissions by ethanol intake port injection for the promotion of premixing of the in-cylinder injected diesel fuel, and by increased EGR for the reduction of combustion temperature.

The compression ratio and expansion ratio are fundamental parameters that determine the thermal efficiency of an SI engine, and the potential of setting these ratios to arbitrary values was studied as a way of improving engine efficiency. First, the efficiency resulting from different compression and expansion ratios was calculated from a theoretical formula. As a result, it was verified that a 20% improvement in thermal efficiency could be expected by adopting a super-high expansion ratio of 20 or higher, which is an extremely large value for an SI engine, while keeping the compression ratio within a range that can ensure appropriate combustion. Subsequently, this research calculated the possibility of improving engine efficiency under a condition that constrains the swept volume to a constant value in consideration of practicability.

Mass reduction of parts is growing in importance as a means for reducing CO2 emissions from vehicles.The aim of the present research was to contribute to further mass reduction of pistons by developing a new aluminum casting material with highest level of fatigue strength. This goal was achieved using a development concept of creating a homogeneous structure in which Ti was added to create a fine structure and appropriate quantities of Fe and Mn were added to form a compound that is stable at high temperatures. Stand-alone tests of prototype pistons fabricated using the developed material show that the material is 14% stronger than the conventional material, thereby enabling increases in power and mass reduction.

The design of the newly developed Toyota AZ series 4 cylinder engine has been optimized through both simulations and experiments to improve heat transfer, cooling water flow, vibration noise and other characteristics. The AZ engine was developed to achieve good power performance and significantly reduced vibration noise. The new engine meets the LEV regulations due to the improved combustion and optimized exhaust gas flow. A major reduction in friction has resulted in a significant improvement in fuel economy compared with conventional models. It also pioneered a newly developed resin gear drive balance shaft.

Toyota Hybrid System (THS), the powertrain that combines a gasoline engine and an electric motor was first introduced in December 1997. It became the first mass-produced hybrid passenger vehicle in the world, gaining a reputation as a highly innovative vehicle, and its cumulative worldwide sales have exceeded 120,000 units. In 2003, THS had a further evolution. The “new-generation Toyota Hybrid System (THS II)” would be introduced on the new Prius. This report shall explain “THS II”, which achieved drastic improvements in power performance and fuel economy, while securing the most stringent emission standard Advanced Technology Partial Zero Emission Vehicle (ATPZEV).

In order to correspond to the exhaust emissions regulations that become severe every year, more advanced engine control becomes necessary. Engine engineers are concerned about the Hydrocarbons (HCs) that flow through the air-intake ports and that are difficult to precisely control. The main sources of the HCs are, the canister purge, PCV, back-flow gas through the intake valves, and Air / Fuel ratio (A/F) may be aggravated when they flow into the combustion chambers. The influences HCs give on the A/F may also grow even greater, which is due to the increasingly stringent EVAP emission regulations, by more effective ventilation in the crankcase, and also by the growth of the VVT-operated angle and timing, respectively. In order to control the A/F more correctly, it is important to estimate the amount of HCs that are difficult to manage, and seek for suitable controls over fuel injection and so on.

CARB (California Air Resources Board) has required the evaporative emissions to be restricted to 1/4th of the parameter stated in the 1995 regulations. Furthermore, hydrocarbons (hereafter, HC) from the fuel system must be reduced to near 0.0 grams, according to the PZEV (Partial Zero Emission Vehicle) regulations enforced from 2003. The wet film in intake ports and fuel leaking from the injector nozzles evaporate and diffuse while the car is parked, and consequently may cause HC to leak the air cleaner inlet. The air cleaner which prevents HC leakage from the air intake system is already in mass production. In the course of designing this product to be installed in a vehicle, the authors developed a method to estimate the amount of HC that reaches the air cleaner. Based on detailed investigation on HC distribution and the changes that occur during parking, the HC amount reaching the air cleaner was calculated by both the equation of diffusion and the equation of state.

The authors have developed an instrument that measures the CO2 concentration in engine combustion chambers using the infrared absorption method. The characteristics of this technology are as follows: 1 Measuring can be carried out while the engine is running at 600r/min to more than 3000r/min, full load operation. (Applicable to all EGR conditions) 2 Quick response; 2ms 3 High linearity; ±1% Full Scale and under (FS: 10%) 4 No aggravation is caused to the intake/exhaust performance of engines This technology contributes to the improvement of the in-cylinder EGR system using, for instance, a variable valve-timing mechanism that is now expanding in number of applications, and also the conventional EGR system.

A new stratified charge system has been developed for direct injection gasoline engines. The special feature of this system is employment of a thin fan-shaped fuel spray formed by a slit nozzle and a shell-shaped piston cavity. This system, basically classified into the wall-guided mixture preparation concept that leads air/fuel mixture to the spark plug periphery by means of spray penetration and piston cavity configuration without an extra intake air flow controlling system, obtained wide engine operating area with stratified combustion and high output performance. This report presents the characteristics of stratified mixture formation and combustion, especially the important factor for achieving stable stratified combustion in the high-speed region, which have been clarified through analytical studies.

Numerical 3-D simulations are performed for the improvement of the new direct injection gasoline engine. A solution based local grid refinement method has been developed in order to reduce the CPU time. This method has been incorporated into the CFD program (STAR-CD) with in-house spray and combustion models. Calculation results were compared with the experimental data taken by the LIF technique, and good agreement was obtained for the mixture formation and combustion processes. Some calculations were carried out for the fuel-air mixture formation process during late injection stratified combustion and the following results were obtained. The unburnt fuel has a tendency to remain in the side of the piston cavity at the latter part of the combustion period. To reduce the amount of unburnt fuel, it was shown that the combination of a thin thickness fan spray and compact cavity forms a spherical mixture, suitable for combustion.

In the field of automotive gasoline engines, new products aiming at greater fuel economy and cleaner exhaust gases are under development with the aim of preventing environmental destruction. Severe ignition environments such as lean combustion, stronger charge motion, and large quantities of EGR require ever greater combustion stability. In an effort to meet these requirements, an iridium plug has been developed that achieves high ignitability and long service life through reduction of its diameter, using a highly wear-resistant iridium alloy as the center electrode.(1)(2) Recently, direct injection engines have attracted attention. In stratified combustion, a feature of the direct injection engine, the introduction of rich air-fuel mixtures in the vicinity of the plug ignition region tends to cause carbon fouling. This necessitates plug carbon fouling resistance.

The Vapor Reducing Fuel Tank System (Bladder Tank System) using a flexible plastic membrane (Bladder Membrane) was newly developed in order to reduce the amount of vaporized gasoline in a steel fuel tank. This Bladder Membrane is flexible to expand in proportion to a fuel volume and prevents the permeation of the vaporized gasoline. As a result of our initial study for various materials, we decided to apply a multi-layer plastic material which could achieve both low fuel permeability and good flexibility. This multi-layer material consists of polyethylene(PE) for structural material and polyamide(PA) for low permeability. The modulus of the PE needs to achieve a sufficient flexibility in order to keep the movement of the membrane. While PA material must have not only low fuel permeability but also strong adhesion with the structural material of PE. We also clarify the membrane design to keep a good flexibility and to reduce a strain.

With the advance in modularization of engine parts in recent years, there is increased use of plastic-made products in air intake systems. Plastic-made intake manifolds (Fig. 1) provide many advantages including reduced weight, reduced cost, and lower intake air temperatures. However, these manifolds have one disadvantage when compared with conventional aluminum-made intake manifolds, in that they transmit more noise because of their lower material density. For example, plastic intake manifolds of early development often generate flow noise when the throttle is opened quickly. With conventional aluminum intake manifolds, this flow noise had generated, but was not heard. This flow noise is presumed to be generated because of high-speed airflow generated when the throttle is opened quickly, but the mechanism of this noise generation has not been clarified.

Authors have developed an apparatus which measures the piston temperature using electromagnetic induction. The characteristics of this apparatus are as follows; 1 Applicable to 6 points per cylinder and all cylinders 2 Capable of measuring while the engine is running from start to 6000r/min full-load operation 3 Wide measuring range; from -30 to 400 °C 4 High accuracy; ±2.5 °C 5 Quick and easy setup 6 High durability This technology contributes to realizing the best balance of piston reliability and matching of combustion conditions. In this report, authors analyzed its influences upon piston temperature when the ignition timing,the oil/water temperature or the oil flow from piston jet were changed, respectively.

A new, free-cutting steel, hereafter referred to as “non-lead-added free-cutting steel”, has been developed with the intention of replacing currently applied lead containing free cutting steel. The ultimate goal of this project is to provide a new lead-free steel grade that will contribute to the removal of environmentally harmful substances from automobile parts. In this project, we have targeted the development of a material that would demonstrate levels of machinability and other mechanical properties equivalent to those of the conventional free-cutting steel to which sulfur (S), lead (Pb) and calcium (Ca) or combinations, thereof have been added. The fine dispersion of sulfide, modified by adding Mg and Ca, is most effective in enhancing the chip breakability that would otherwise deteriorate due to the absence of lead. The practical application of the non-lead-added free-cutting steel has rendered the goal of total removal of lead from special steel products highly obtainable.

The tendency of spark ignition direct injection (SIDI) engines to form injector deposits was investigated using engine dynamometer tests on a SIDI engine equipped with fan spray type injectors. Fifteen test fuels with varying 90% distillation temperature (T90), aromatics, olefins, oxygenates and sulfur levels were prepared to identify the effects of fuel properties on injector deposits. The results suggested that not only the T90 but also the number of alkyl substituent of aromatics had effects on injector deposit formation. Effects of detergents on the injector deposit cleanliness were also evaluated in this study.

Methanol steam reforming, which is an endothermic reaction, needs some heating. Both methanol conversion ratio and carbon monoxide (CO) concentration increase when temperature is elevated. As CO poisons a typical polymer electrolyte of a fuel cell, the relationship between methanol conversion ratio and CO concentration is a trade-off one. It was found from preliminary researches that the reforming reaction speed is controlled by heat transfer rate at large methanol flow rate, where methanol conversion ratio becomes lower and CO concentration becomes higher. Therefore it is necessary to develop a new methanol reforming concept that provides stable combustion for heating and enhanced heat transfer for improving the trade-off relationship and making a compact reformer. Reforming catalyst using metal honeycomb support and a new catalytic combustion were applied to a new concept plate type methanol steam reformer, which is used in a fuel cell of 3 kW-class electric generation.