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We developed a unique reducing additive composed primarily of polyolester, diester, and vegetable oil-based ester compounds in order to switch from boundary to fluid lubrication and improve tribology performance, and chemically and experimentally investigated its effects on tribology performance. To confirm the lubrication effects of this reducing additive, we added it to oil and chemically investigated the cleaning and dissolving of the ultra-fine particle layer of contaminants, etc., adhering to lubrication pathways and sliding surfaces, and performed commercialization testing using actual vehicles. We found that this additive washed away and dissolved sludge, varnish, and other contaminants from lubricated surfaces, improving their lubrication properties and their tribology performance by reducing abrasion and friction.

Exhaust and evaporative emissions systems have been developed to match the characteristics and usage of the Toyota THS II plug-in hybrid electric vehicle (PHEV). Based on the commercially available Prius, the Toyota PHEV features an additional external charging function, which allows it to be driven as an electric vehicle (EV) in urban areas, and as an hybrid electric vehicle (HEV) in high-speed/high-load and long-distance driving situations. To reduce exhaust emissions, the conventional catalyst warm up control has been enhanced to achieve emissions performance that satisfies California's Super Ultra Low Emissions Vehicle (SULEV) standards in every state of battery charge. In addition, a heat insulating fuel vapor containment system (FVS) has been developed using a plastic fuel tank based on the assumption that such a system can reduce the diffusion of vapor inside the fuel tank and the release of fuel vapor in to the atmosphere to the maximum possible extent.

In this study, it was shown that Homogeneous Charge Compression Ignition (HCCI) combustion in a 4-stroke engine, operating under the conditions of a high compression ratio, wide open throttle (WOT) and a lean mixture, could be simulated by raising the compression ratio of a 2-stroke engine. On that basis, a comparison was then made with the characteristics of Active Thermo-Atmosphere Combustion (ATAC), the HCCI process that is usually accomplished in 2-stroke engines under the conditions of a low compression ratio, partial throttle and a large quantity of residual gas. One major difference observed between HCCI combustion and ATAC was their different degrees of susceptibility to the occurrence of cool flames, which was attributed to differences in the residual gas state. It was revealed that the ignition characteristics of these two combustion processes differed greatly in relation to the fuel octane number.

Homogeneously charged natural gas was burned in a diesel engine assisted by a small amount of gas oil injection. The effects of the equivalence ratio of natural gas, the intake temperature and the EGR rate on ignition of gas oil, the burning rate of natural gas and the knock limit were clarified experimentally. As results, a marked improvement in the trade-off between smoke and NOx was obtained maintaining a high thermal efficiency by a combination between the natural gas charge rate, the EGR rate, the intake preheating and the nozzle orifice size suitable at each engine load.

A new exhaust emission control system has been developed which complies with the world's most severe emission standard: CARB PZEV. Leaner combustion in cold condition was enabled and rapid warm-up of a close-coupled catalyst was realized by utilizing a newly developed Intake Air Control Valve (IACV) system and hyper-atomization fuel injector. In addition, the newly developed HC adsorbing type 3-way catalyst realized cold HC reduction at lower cost. For further reduction of the exhaust emission, the Variable Valve Timing-Intelligent (VVT-i) system was positively operated immediately after the cold start. By the suitable operation of Variable Valve Timing (VVT), the blow-back from the cylinder enhanced the fuel atomization and re-burning of remaining unburned hydrocarbons (HCs), and increased in-cylinder residual gas reduces NOx.

Regulations on exhaust emissions from light- and heavy-duty diesel engines have generated interest in high-pressure fuel injection systems. It has been recognized that high-pressure injection systems produce fuel sprays that may be more conductive to reducing exhaust emissions in direct-injection diesel engines. However, for such a system to be effective it must be matched carefully with the engine design and its operating parameters. A common-rail type of fuel injection system was investigated in the present study. The injection system utilizes an intensifier to generate injection pressures as high as 160 MPa. The fuel spray characteristics were evaluated on a test bench in a chamber containing pressurized nitrogen gas. The injection system was then incorporated in a single-cylinder diesel engine. The injection system parameters were adjusted to match engine specifications and its operating parameters.

This paper provides an insight into the design of a compound combustion chamber, with square and circular cavities, for use in a direct-injection diesel engine. Automotive diesel engines using square combustion chamber design have shown improvement in oxides of nitrogen and particulate exhaust emissions. In spite of this, neither the quality of mixture formation in such chambers nor the relationship between the engine performance and combustion chamber designs have been adequately addressed. Compound combustion chambers have potential to combine attributes of square and circular chambers to provide improved engine performance. An experimental study, based on liquid injection technique (LIT), was conducted to evaluate mixture formation in compound combustion chambers of different designs. These chambers have square geometry of depth "h" at the top and a curricular cavity at the bottom, with the total chamber depth being "H."

A newly-developed time resolved exhaust gas analysis system was utilized in this study. The hydrocarbon compositions upstream and downstream of the catalytic converter were investigated during cold start and warm up of the Federal Test Procedure(FTP), with three fuels of different aromatic contents. Although engine-out hydrocarbon emissions had high concentrations right after cold start, the specific reactivity was low. This can be explained by the selective adsorption of the high boiling point components which had a high Maximum Incremental Reactivity (MIR) in the intake manifold and engine-oil films. Thereafter, the high boiling point components were desorbed rapidly and consequently specific reactivity increased. Hydrocarbon adsorption of high boiling point components and hydrocarbon conversion of low boiling point components occurred simultaneously on the catalyst during warm up.

A new liquid-liquid injection technique with a rigid swirling water flow and a single shot photograph was developed to make observation of a fuel-air mixing process, and then to understand its characteristic quantitatively. In this technique, a liquid fuel was injected into an other liquid to simulate the process of diffusion in a piston cavity of an actual engine. This experiment has been made employing four different configurations of plastic piston cavities; dish, troidal, bowl and square type. These cavities were filled with water and rotated to generate the rigid swirling water flow. Observations from the bottom and side view indicated that the mixing process in the square configuration markedly depends on the orientation of the spray, due to both effects of the swirl and the impingement of the spray on the side wall. The technique is a potential to visually understand the mixing process.