To reduce detrimental substances contained in the exhaust gas by specifying the distance between the opposing walls of a shallow tray type combustion chamber.
A direct injection type diesel engine has a shallow tray type combustion chamber 4 formed on the top face 10 of a piston 1 in such a way as surrounded by the piston 1, cylinder head 2 and cylinder, and the fuel is injected from a fuel injection valve and atomized to be combusted, wherein the diameter of the combustion chamber 4 as the distance between its opposing walls is decided so that the ratio Vs/Vsp becomes below 1.25, where Vs represents the velocity of a counter-skish flow formed chiefly from opposing skish areas 6 of the top face 10 of the piston 1 and the cylinder head 2 and directed from the combustion chamber 4 to the skish area while Vsp represents the atomization speed in the neighborhood of the lip part of the open wall part of the combustion chamber 4 near the upper dead point in the compression stroke, and it is arranged so that the skish areas 6 constitute part of the combustion chamber 4.
INAYOSHI MINAJI
INAGAKI KAZUHISA
HOTTA YOSHIHIRO
TOUTO TAKAYUKI
