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A phosphor thermometry, for measurements of two-dimensional gas-phase temperature was examined in turbulent combustion in an engine. The reasonable temperature deviation and the agreement with calculated data within 5% precision were achieved by single-shot images in the ignition process of compression ignition engine. Focusing on the local flame kernel, the flame structure could be quantitatively given by the temperature. It became evident that the HCCI flame kernels had 1-3 mm diameter and the isolated island structures. Subsequently, the HTR zone consisted of the combined flame kernels near TDC.

Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. This paper describes the improvement of piston bowl geometry to achieve a more homogeneous gas flow and fuel-air mixture. This concept reduced fuel consumption by 2.5% compared to the original piston bowl geometry, while also reducing NOx emissions by 10%.

Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losseses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. To improve these problems Toyota applied a new concept which was characterized by tapered shape design on the upper portion of the piston and low compression ratio to achieve more homogeneous gas flow and fuel-air mixture. This paper describes the impact of new combustion concept and the mechanism of the improvement by 3D-CFD analysis and optical measurement.

Ignition and combustion control of HCCI (Homogeneous Charge Compression Ignition) in DI (Direct Injection) Diesel Engine were examined. In this study, double injection technique was used by Common Rail injection system. The first injection was used as an early injection for fuel diffusion and to advance the changing of fuel to lower hydrocarbons (i.e. low temperature reaction). The second injection was used as an ignition trigger for all the fuel. It was found that the ignition of the premixed gas could be controlled by the second injection when the early injection was maintaining low temperature reaction. It was found that as the boost pressure increased, ignition timing advanced slightly and the rate of pressure increase markedly decreased. The rate of pressure increase is one of the factors concerning operation limit in this combustion. Therefore, the VNT (Variable Nozzle Turbo-charger) was applied to the production engine to allow boost pressure control.

The dynamics model and model-based controller (LQG servo controller) have been constructed to improve performance of diesel engine in transient condition. The input parameters of the model are fuel quantity of main injection, timing of main injection, fuel quantity of pilot injection, timing of pilot injection, external EGR ratio and boost pressure. The parameters that are succeeded between cycles to express transient condition are residual gas temperature and of residual oxygen. In the model, one cycle is discretized into 10 representative points. The precision of the accuracy of the model and the responsiveness of the controller were confirmed.