| 摘要 |
<p>PURPOSE:To allow intake air to flow smoothly in large quantity against the intake flow of a low-speed intake passage by providing a recessed part at a high-speed intake passage wall corresponding to a turning peripheral part moving onto the upstream side at the opening time of a shutoff valve. CONSTITUTION:In the high speed region of an engine, a shutoff valve 12 is opened under rotating with a first turning peripheral edge part 13a moving onto the downstream side of a first intake passage 10 and a second turning peripheral edge part 13b moving onto the upstream side of the passage 10. In the fully opened state, the first turning peripheral edge part 13a is displaced more onto the downstream side of intake flow from a second intake passage 11 than the center axis L of the first intake passage 10. A recessed part 17 is formed at an upper wall 10a on the opposite side to the center axis L in relation to the second turning peripheral edge part 13b. As a result, a gap between the second turning peripheral edge part 13b and the passage wall of the first intake passage 10 is enlarged, thus securing the larger passage cross-section. Intake air from the first intake passage 10 can thereby flow smoothly in large quantity against the intake flow of the second intake passage 11 so as to secure the intake flow in the high speed region of the engine.</p> |
