Intake system for engine.

摘要

An engine intake system including a primary port (42) for introducing intake gas throughout entire engine operating condition, a secondary port (52) provided with a gate valve (16) which is opened in a high engine load condition for introducing the intake gas, a ratio of a tumble flow to a swirl flow is gradually increased as the gate valve is operated from an entirely close condition to a fully open condition. The ignition and combustion characteristics can be improved. <IMAGE>