| 摘要 |
<p>A valve plate is formed as a butterfly-type valve plate including a first and a second valve-plate half portions that extend in opposite directions to each other from a valve shaft. When the valve plate is at a first changeover position, the first valve-plate half portion is directed to the downstream side of a first intake passage from the valve shaft and the second valve-plate half portion is directed to the upstream side of the first intake passage from the valve shaft so that a first plate face of the valve plate forms a part of the first intake passage. When the valve plate is at a second changeover position, the first valve-plate half portion is directed to the downstream side of a second intake passage from the valve shaft and the second valve-plate half portion is directed to the upstream side of the second intake passage from the valve shaft so that a second plate face of the valve plate forms a part of the second intake passage. Accordingly, the power needed for changing over the valve plate and for keeping a predetermined changeover position can be reduced significantly.</p> |
