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The technologies which comprise heat insulated turbo compound engine are summarized as (1) establishment of heat insulation structure. (2) improvement of combustion under high temperature ambient condition. (3) establishment of energy recovering from exhaust gas.

This is a descriptive review of the ceramics structural applications developed by Isuzu, Mazda, Nissan, Toyota and General Motors in spark ignition, Diesel and gas turbine automotive engines; new analytical procedures needed for the design of structural ceramics; new silicon nitride ceramics with strength of material properties approaching steel; new ceramics processing techniques which have been reduced to commercial practice in Japan on a mass production scale; and tests of vital structural components fabricated of these ceramics.

An adiabatic engine was constructed with the monolithic type ceramic material. A highly durable and superior heat insulating engine could be completed, through detailed study of the design, evaluating the ceramics of which reliability is inferior in strength, going back to the microstructure and improving it to the utilizable level as the engine parts. I started studying the combustion in a bid to accomplish improvement of the fuel consumption rate, realization of multi-fuel engine and pollution-lowering, but I found out that recovering of the ignition delay shortening can be coped with by high pressure injection, fuel nature modification and so forth. In future, I have to pursue my studies in connection with reduction of emission of exhaust gas like the NOx and recovery of energy from the exhaust gas, and the similar subjects.

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 describes the development of new Si3N4 ceramics with both low friction coefficient and high strength, aiming at the reduction of friction force between cylinder liner and piston ring in low heat rejection engine. Si3N4 ceramics has high Young's modulus, therefore it provides lower coefficient of friction than iron. We thought that if adsorption ability of Si3N4 to lubricant oil were improved, coefficient of friction got still lower. In order to achieve this Fe3O4, which has superior adsorption ability, were used as one of additives for Si3N4. The obtained new Si3N4 had obviously lower coefficient of friction than conventional Si3N4 and it's strength were almost same as conventional Si3N4. Moreover, cylinder liner and piston ring were fabricated from developed Si3N4. They were tested using engine and reduction of friction force was confirmed.

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.

For the purpose of eliminating a cooling device from conventional diesel engines, a heat insulation structure referred to as thermos structure was adapted in a low heat rejection (LHR) diesel engine. The thermosstructure is constructed by a combustion chamber wall made of Si3N4 monolithic ceramics having higher strength and fracture toughness at much higher temperature and the heat insulation layers combined with air gap and gaskets with low thermal conductivity that are located behind the combustion chamber wall. Although the insulated engine achieved reduced heat rejection from the combustion chamber with the thermos structure, improvement in fuel economy and exhaust emissions could not be realized in the case of a diesel engine with Direct Injection (DI) system.

This paper describes the startability of small swirl chamber diesel engines which is inherently inferior to gasoline engines, particularly in the cold climate operation, and a new start assisting system using silicon nitride ceramic glow plugs which offers the same level of convenience in engine starting as in gasoline fueled vehicles, i.e. elimination of waiting time before engine start, through a remarkable reduction in the plug preheat period. The paper also details the new features of the ceramic glow plug capable of withstanding high engine temperatures and the abrupt temperature changes overcoming brittleness, a major developmental stumbling block, in comparison with the conventional metal glow plug.

Ceramics show high degree of heat resistance. But an attempt to build an adiabatic engine using ceramic materials should be carried out by full evaluation of characteristics of each ceramic material. The strength of ceramic parts are dependent on both their manufacturing processes and the mechanical and thermal stresses to which the parts are subjected. Full consideration should be given to these factors in evaluating ceramic parts. Even if a ceramic engine were manufactured after full consideration (1) to these factors, adiabatic engines proposed by R. Kamo and other researchers have had difficulty in realizing performance level and fuel economy as first suggested.

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.

New diesel particulate filter (DPF) by using nonwoven fabric made of silicon carbide (SiC) ceramic fiber and formed cylindrical shape with bellows folds has been developed. It has very high durability and excellent filtration performance. It has the unique filter structure that nonwoven cloth made of SiC fiber is held between two metal wire cloths in order to make the filter clogged by Particulate Matter (PM) regenerate. Urban buses equipped with this new DPF already run about 40,000km around Tokyo metropolitan and Kawasaki City area.