Marine propulsion unit

Abstract

Marine propulsion unit, where said unit comprises a streamlined body, where said body has a front end and a rear end, where in use the front end will be facing upstream and the rear end downstream, where the front end has a larger cross section perpendicular to the intended travelling direction than the rear end, and where the front end is provided with a water inlet opening, where said opening is in communication with an impeller, which impeller rotates around an axis parallel to the intended travelling direction, where said impeller has one or more vanes whereby the water entering the front end is expelled radially away from the impeller's rotating axis, where said expelled water is forced through one or more rectifier nozzles directing said expelled water along the outer surface towards the rear end of the streamlined body.

1 . A marine propulsion unit, where said propulsion unit comprises a streamlined body, where said body has a front end and a rear end, where in use the front end will be facing upstream and the rear end downstream, where the front end has a larger cross section perpendicular to the intended travelling direction than the rear end, and where the front end or adjacent the front end, is provided a water inlet opening, where said opening is in communication with an impeller, which impeller rotates around an axis parallel to the intended travelling direction, where said impeller has one or more vanes whereby the water entering the inlet opening is expelled radially away from the impeller's rotating axis, where said expelled water is forced through one or more nozzles directing said expelled water along the outer surface of the streamlined body. 
     
     
         2 . The marine propulsion unit according to  claim 1  wherein the streamlined body or body of revolution at zero incidence is symmetric around the impeller's rotation axis. 
     
     
         3 . The marine propulsion unit according to  claim 1  wherein a cross section through a longitudinal plane of the streamlined body has a drop shape, where the rear end tapers. 
     
     
         4 . The marine propulsion unit according to  claim 1  or  2  or  3  wherein the streamlined body is provided with means for attaching the unit to a vessel, where said means are suitable to transfer the thrust to said vessel. 
     
     
         5 . The marine propulsion unit according to  claim 4 , wherein the means is the vessels propeller axle, where the unit is installed instead of the propeller, and where the axle rotates the units' impeller. 
     
     
         6 . The marine propulsion unit according to  claim 1  wherein inside said stream-lined body motor means are provided for rotating the axle of the impeller. 
     
     
         7 . The marine propulsion unit according to  claim 1  wherein the water inlet opening, the impeller and the one or more nozzles are arranged on the surface of the streamlined body, such that expelled water exiting through the nozzles will be directed along the outer surface of the streamlined body. 
     
     
         8 . The marine propulsion unit according to  claim 1  wherein the nozzle has a circular shape, arranged around the impeller on the surface of the streamlined body, and where the nozzle is separated into sections. 
     
     
         9 . The marine propulsion unit according to  claim 1  wherein the vanes arranged on the impeller all are spaced at a radial distance from the rotation centre of the impeller, leaving a central area of the impeller as an open vane free surface, said surface having a plane substantially perpendicular to the impeller's rotation axis. 
     
     
         10 . The marine propulsion unit according to  claim 1  wherein the one or more vanes are arranged substantially radial on the impeller, and where the one or more vanes are curved relative to a radial going through said vane, whereby the vane will expel water substantially radial from said impeller. 
     
     
         11 . The marine propulsion unit according to  claim 1  wherein the vanes arranged on the impeller can be oriented or adjusted relative to a radial direction. 
     
     
         12 . The marine propulsion unit according to  claim 1  where the nozzles are provided with rectifying means in the shape of walls and a lid, where said walls and lid may by controlled relative to the water flow, said rectifying means directing the expelled water into a radial direction relative to the impellors axis, whereby the expelled water is led along the surface of the body. 
     
     
         13 . The marine propulsion unit according to  claim 1  wherein at least part of the surface area of the streamlined body is provided with a plurality of dimples and/or indentations and/or bulges. 
     
     
         14 . The method of providing propulsion, wherein a marine propulsion unit according to  claim 1  is arranged on a submerged section of a marine vessel where water is channeled into the propulsion unit's inlet opening, and the water is accelerated when coming into contact with the vanes arranged on a rotating impeller, such that the water is expelled through nozzles from the impeller along the surface of the propulsion unit, such that the accelerated water on a front section of the propulsion unit creates an under-pressure and along the rear part of the unit provides a thrust, providing the propulsion. 
     
     
         15 . The method of providing propulsion, wherein a marine propulsion unit according to  claim 1  is arranged below on a submerged section or a submerged cavity in the front end of the pod whereas the speed of the vessel and thereby the marine propulsion unit  1 , the ambient pressure will rise, in the water in contact with the submerged impeller and the rectifier nozzles and will delay the inception of cavitation in the thrust generating parts of the total propulsion system, stemming from the relative flow velocity in relation to the local pressure. 
     
     
         16 . The marine propulsion unit according to  claim 2  wherein a cross section through a longitudinal plane of the streamlined body has a drop shape, where the rear end tapers. 
     
     
         17 . The marine propulsion unit according to  claim 2  wherein the streamlined body is provided with means for attaching the unit to a vessel, where said means are suitable to transfer the thrust to said vessel. 
     
     
         18 . The marine propulsion unit according to  claim 3  wherein the streamlined body is provided with means for attaching the unit to a vessel, where said means are suitable to transfer the thrust to said vessel. 
     
     
         19 . The marine propulsion unit according to  claim 2  wherein inside said stream-lined body motor means are provided for rotating the axle of the impeller. 
     
     
         20 . The marine propulsion unit according to  claim 16  wherein inside said stream-lined body motor means are provided for rotating the axle of the impeller. 
     
     
         21 . The marine propulsion unit according to  claim 4  wherein inside said stream-lined body motor means are provided for rotating the axle of the impeller. 
     
     
         22 . The marine propulsion unit according to  claim 9  wherein the one or more vanes are arranged radially on the impeller, and where the one or more vanes are curved relative to a radial going through said vane, whereby the vane will expel water substantially radial from said impeller. 
     
     
         23 . The marine propulsion unit according to  claim 10  wherein the vanes arranged on the impeller can be oriented or adjusted relative to a radial direction. 
     
     
         24 . The marine propulsion unit according to  claim 1  wherein at least part of the surface area of the streamlined body is provided with a plurality of indentations. 
     
     
         25 . The marine propulsion unit according to  claim 1  wherein at least part of the surface area of the streamlined body is provided with a plurality of bulges. 
     
     
         26 . The marine propulsion unit according to  claim 9  wherein the one or more vanes are arranged substantially radial on the impeller, and where the one or more vanes are curved relative to a radial going through said vane, whereby the vane will expel water substantially radial from said impeller. 
     
     
         27 . The marine propulsion unit according to  claim 3  wherein inside said stream-lined body motor means are provided for rotating the axle of the impeller.