PURPOSE: To quickly accomplish ignition by installing a sparking plug, with the shaft center thereof inclined in such a manner that the opposite end portion to a discharge portion in the sparking plug is directed upward on the inner surface of a cavity where the discharge portion of the sparking plug faces.
CONSTITUTION: In an engine where a fuel injection system 46 is provided in a combustion chamber 37, a sparking plug 79 is disposed in such a manner that the shaft center 81 is inclined to a steep inclined surface 75 of a cavity 74 where a discharge portion 80 faces and the end portion 82 of the sparking plug 79 is directed above a virtual perpendicular 83 of the steep inclined surface 75. Thus even if the discharge portion 80 is positioned enough below the cavity 74, a cylinder head 30 below the sparking plug 79 can have enough thickness, and a water-cooled jacket can be formed. The open edge of the cavity 74 positioned below the sparking plug 79 is projected toward the inside of the cavity 74, and a forming surface 85 for a squish is provided on the projected portion 84. Thus, the squish 90 can be prevented from being directly blown against the discharge portion 80.
TANAKA TAKESHI
YASHIRO YOSHINOBU
KAWABE HIDEAKI
KINOSHITA TOSHIO
ISAKA YOSHIHARU
SUZUKI HIROMI
