| 摘要 |
PURPOSE:To obtain a smooth torque characteristic over the whole rotational speed range of an engine by changing the cross-sectional area of a communication passage downstream of an annular resonance intake-air passage for supercharging intake-air under the resonance tuning of intake-air, in accordance with a rotational speed of the engine. CONSTITUTION:An intake-air passage communicated to the intake-air ports of engine cylinders 2a through 2f is composed of an independent intake-air passage 5, an annular resonance intake-air passage 6 and an intake-air supply passage 10. Further, the annular resonance intake-air passage 6 is composed of a center communication passage 7, an upstream communication passage 8 and a downstream communication passage 8. In this arrangement, a pair of shutter valves 14 which are opened and closed in synchronization with each other, are disposed in the downstream communication passage 9 on the side connected to the center communication passage 7. These shutter valves 14 increase their opening degrees in proportion to an increase in the rotational speed of the engine. That is, the cross-sectional area of the downstream communication passage 9 varies in accordance with a rotational speed of the engine.
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