Patent ID: 6102757
Filing Date: 2000-08-15
Classification: B63H

Abstract:
A water jet propulsion apparatus for a ship partially submerged below a surface of the water, comprising:a pump frame having an upper opening, a lower opening and a water passage for establishing a communication between the upper and lower openings, the pump frame is adapted to be joined to a bottom of a ship in such a manner that the lower opening is opened into water adjacent to a stern of the ship;a mixed flow pump having a suction casing with a suction opening, a pump casing with a discharge opening, a rotatable main shaft arranged substantially horizontally in the pump casing, an impeller fixed to the main shaft within the pump casing, and guide blades within the pump casing, the suction opening arranged to be continued from the upper opening, the suction casing arranged to establish a communication between the pump casing and the pump frame, the impeller sucking water below the bottom of the ship through the lower opening so as to pressurize water;a discharge pipe connected to the discharge opening of the mixed flow pump and arranged to jet out water pressurized by the impeller toward a rear of the stern of the ship, whereinthe impeller comprises a hub fixed to the main shaft and blades spirally extending from the hub,each of the blades has an outer end disposed adjacent to an inner surface of the pump casing and a front edge extending from the hub toward the suction casing and inclined relative to the main shaft to increase an introduction area of the impeller substantially, andeach of the guide blades has a long and twisted shape and arranged around the main shaft between the discharge opening and the blade.