| 摘要 |
PURPOSE:To diffuse a large quantity of exhaust gas bubbles at the periphery of blade parts and contrive to enhance starting accelerating property, by a method wherein an ON-OFF valve which is closed under the action of a centrifugal force of not smaller than a predetermined value is provided in a through- hole. CONSTITUTION:At the time of a starting acceleration, a propeller 19 is rotated at a low speed, and a centrifugal force exerted on a valve body 30 is small, so that the propeller is maintained in the direction opposite to a valve seat 31 by an energizing force of a spring 32, and the through-hole 28 is maintained in a conducting state. Accordingly, a large quantity of an exhaust gas flows out to the outer peripheral part of a boss part 22 through an exhaust gas passage 26 and the through-hole 28, a large quantity of exhaust gas bubbles are diffused to the periphery of the blade parts 21, whereby the resisting force exerted from water to the propeller 19 at the time of the starting acceleration is reduced, and acceleration can be promoted. At the time of normal steaming, the through-hole 28 is maintained in a non-conducting state, whereby diffusion of exhaust gas bubbles to the periphery of the blade part 21 is eliminated, and an or iginally expected thrust can be obtained. |
