To improve combustion efficiency, to reduce a PM quantity, and to improve startability.

This swirl chamber type diesel engine has a main chamber 3 and a spherical sub-chamber 2. An opening part of a glow plug installing hole 10 of an inner wall surface of the sub-chamber 2 is expanded, and a recess 9 is arranged between this opening part and a glow plug 8, and its inside is constituted so as to be capable of staying a part of a flow of a swirling flow 7. When injecting fuel 6 by a fuel injection nozzle 5 in a state of generating the swirling flow 7 in the sub-chamber 2 in a compression stroke, since its part stays in the recess 9 together with a part of the flow of the swirling flow 7, even in a low state of the wall surface temperature of the sub-chamber 2, a stable flame is formed in the recess 9, and the startability is improved. While, by limiting staying in the recess 8 to a part of the flow of the swirling flow 7 generated in the sub-chamber 2, the whole swirling flow 7 in the sub-chamber 2 is not weakened, so that influence on reduction in the combustion efficiency and an increase in the PM quantity is minimally restrained.

COPYRIGHT: (C)2010,JPO&INPIT