PURPOSE: To aim at making suitable adjustment of an intake air temperature with a simplified construction by providing an air intake water jacket hollowly on a mounting portion on a manifold side, which is to be mounted on a mounting portion of a cylinder head portion, and also an intake air cooling water thermostat is provided to manage the temperature of the intake air cooling water.
CONSTITUTION: When an engine is operated, engine cooling water flows from a water jacket 100 of a cylinder block 20 to a water jacket 102 of a cylinder head 32 and cools the engine. In this case, intake air cooling water is discharged from intake thermostat 114 after being run through a water jacket 110 for intake air. Thus, temperature of intake air around a fuel injection valve and flowing from a branched off intake pipe 62 to an intake port 36 is adjusted and thereby combustibility and filling efficiency are improved. Now the water jacket 110 for intake air is provided depressedly on a manifold side mounting portion 68 which is to be mounted on a head side mounting portion 70. Thus it solves the mold structure of an intake manifold 58 from becoming complicated.
DAIKOKU KEISUKE
OTA MITSUHIKO
SHOMURA NOBUYUKI
YOSHIOKA HIDEHIKO
SAIGA JIRO
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