| 摘要 |
PROBLEM TO BE SOLVED: To obtain an internal combustion engine with high volume efficiency by setting an attachment angle of a throttle valve such that air passing the throttle valve in a full-open state always flows in the direction toward an open port. SOLUTION: An attachment angle of a throttle valve 10 is always set in the direction toward an open port 7. When the throttle valve 10 attached to a small tubular portion 1a is full open and a port area variable valve 5 is closed, substantially all air passing through the throttle valve 10 always flows into the open port 7. The air does not happen to flow in the reverse direction to a valve opening/closing port 6. Thus, an intake system of an internal combustion engine with improved volume efficiency can be achieved. Since the purpose is achieved only by adjusting the attachment angle of the throttle valve 10 to the small tubular portion 1a, additional parts are unnecessary. Accordingly, ventilation resistance is reduced and volume efficiency can be improved.
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