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In order to clarify the state of spray and mixture formation in a diesel engine cylinder, the formation technique of high temperature and high pressure conditions in a constant-volume chamber was developed. This technique reproduces actual cylinder conditions (for example, 5MPa and 873K at TDC in NA engines with a compression ratio of 16) by filling ambience formation mixture into the chamber and pre-igniting the mixture. LIEF (Laser Induced Exciplex Fluorescence) technique was applied to the analysis of vapor-liquid separation as the measurement of spray. However, the light emission from various aromatic compounds by laser irradiation makes it difficult to apply the technique to the evaluation of the actual fuel. Therefore the preparation technique of the fuel for this LIEF technique was developed to have a mixture formation state on fuel properties.

In order to clarify the diesel fuel spray characteristics inside the cylinder, we developed two novel techniques, which are preparation of same level of temperature and pressure ambient as inside cylinder and quantitative measurement of vapor concentration. The first one utilizes combustion-type constant-volume chamber (inner volume 110cc), which allows 5 MPa and 873K by igniting the pre-mixture (n-pentane and air) with two spark plugs. In the second technique, TMPD vapor concentration is measured by using Laser Induced Exciplex Fluorescence method (LIEF). The concentration is compensated by investigation of the influence of ambient pressure (from 3 to 5 MPa) and temperature (from 550 to 900 K) on TMPD fluorescence intensity. By using two techniques, we investigated the influence of nozzle hole diameter, injection pressure and ambient condition on spray characteristics.

In order to eliminate a cooling system from an internal combustion engine, we studied structures to reduce heat rejection from a combustion chamber. It was known to be very difficult to increase the heat-insulation rate of a low heat-rejection engine with a coated combustion chamber wall with a zirconia layer to more than 50%. Therefore a heat flux and temperatures were calculated by using the finite-element method in order to develop a new structure for a low heat rejection engine. The calculation results were compared with the temperatures measured in the engine which was fabricated with a silicon nitride combustion chamber wall incorporated in a heat-insulation structure composed of an air gap and a gasket of very low thermal conductivity. The result was that the compound heat-insulation structure was very effective in reducing heat rejection from the combustion chamber wall to the outer cylinder made of cast iron.

Methanol fuel was tested in a prototype 2-cycle ceramic heat insulated engine with a swirl chamber. It was found that the 2-cycle ceramic heat insulated engine with a compression ratio of 18:1 could ignite methanol without an auxiliary ignition system and emissions were substantially reduced in the whole load range.

This paper describe the metal-to-ceramic joining method which is important for building ceramic adiabatic engine and deals with the potential of pistons for use for adiabatic ceramic engine. Although various ceramic-to-metal joining methods have been developed, the chemical bonding method such as brazing and diffusion bonding is not only inferior in complex joining process and heat resistance, but also incapable of attaining the bonding strength of 196Mpa required of engineering ceramics. The ceramic-to-metal bonding attained generally by mechanical method such as staking results in the failure of ceramic bonding face due to a strong shearing force accompanied by the plastic deformation of metal. Therefore, the reduction of the shearing force between the ceramic and metal materials and the improvement of plasticity of the metal are necessary.