Kimitaka Saito

Analysis of Oil Consumption at High Engine Speed by Visualization of the Piston Ring Behaviors

In the internal combustion engine, it is well-known that oil infiltrates the combustion chamber through the clearance between the piston ring and the cylinder bore with a vertical reciprocating motion of the piston, leading to an increase in oil consumption. The author et al. made a glass cylinder engine in which a closed piston ring gap could be visualized, based on the idea that piston ring conformability to the sliding surface of the bore could be evaluated from minute changes of the piston ring gap. This newly-devised visualized engine was an in-line 4cylinder engine, capable of running up to 6000 rpm, in which the closed gap of the piston ring could be observed minutely during engine operation. As the result of the evaluation of the piston ring conformability to bore with this equipment, it was found that the upward passage of oil widened and the oil consumption increased, because abnormal behavior, that is, the separation of the piston ring from the deformed portion of the cylinder bore at the down-stroke of the piston, had occurred in the area of high speed.

New concept of a direct injection SI gasoline engine: a study of stratified charge combustion characteristics by radical luminescence measurement

Abstract A new stratified charge system, which employs a thin fan–shaped fuel spray and a shell–shaped position cavity, has been developed for direct injection gasoline engines. In order to clarify the characteristics of stratified mixture formation and combustion, spray motion visualization, local fuel concentration in piston cavity, and frame behavior observation were performed. The newly developed system achieves stable stratified combustion in the high-speed region due to optimized piston cavity shape and fuel spray characteristics, especially suitable spray penetration with high injection pressure which ensures the mixture formation is “robust” against air flow and accelerating mixture diffusion in the cavity.

Analysis of mixture formation of direct injection gasoline engine

In a direct injection gasoline engine, in order to achieve good stratified combustion, an extremely advanced control of air–fuel mixture is required. For this purpose, the method of diagnosing the quality of the state of mixture formation in combustion chambers becomes necessary. In this research, the state of air–fuel mixture in the combustion chamber of a TOYOTA D-4 was analyzed in space and time by visualization, A/F multi-point measurement and A/F high response measurement, and thus the effects that injection timing, swirl and fuel pressure exerted on mixture formation were elucidated.