Photographic Study of Combustion in a Pre-Combustion Type Diesel Engine : (1st Report, Combustion in a Pre-Combustion Chamber)

抄録

Air motion as well as mixture formation and flame pattern in the pre-combustion chamber of a Diesel engine was investigated by means of high-speed photography through a glass window on an engine in operation. By comparing the photographic evidences with the results of test performed under a similar condition, the following conceptions as to the improvement on the combustion were obtained : The main bulk of fuel should be transferred into the cylinder with the first blast of gas so that combustion in the pre-combustion chamber may take place under lean mixture. This state can be realized by keeping the fuel spray from being wafted back by an incoming air-stream and by concentrating a rich mixture near the throat of the chamber. Further, the mixture formation in the chamber is affected to a great extent by an air-stream, which flows in through the small passage during the compression stroke and then generally creates an air-swirl in the main part of the chamber. An excessively vigorous swirl sometimes results in preventing the earlier outflow of fuel, which brings about much soot formation.