| 摘要 |
PURPOSE: To sufficiently decrease exhaust pressure of an exhaust gas discharging device by installing a conical sub-portion circumferentially extending for a prescribed angle at a rear part of a torpedo-shaped gear case supporting a propeller shaft in a marine propulsion device. CONSTITUTION: A lower unit 11 for a marine propulsion device, such as an outboard motor or a stern drive unit has a strut or drive shaft housing 13 having, at the lower end thereof, a gear case 15 which supports a propeller shaft 17. A gear case 15 has a torpedo-shaped part 31 which is integrally provided with a triangular vertical member 37 on its undersurface. The torpedo- shaped part 31 is equipped with a forward portion 41, a central portion 43 which extends rearwardly from the forward portion 41 and has a generally cylindrical configuration 45 concentric with an axis, a stern portion 47 which includes a circumferentially extending cylindrical sub-portion 48, and a conical sub-portion 51 circumferentially extending for about 180 degree. The sub-portion 51 also includes a projection 61 extending radially outwardly along the upper surface 35, thereby increasing local pressure. |
