A vessel and a method in a vessel with a hull and a propulsion unit

Abstract

A vessel and a method in a vessel with a hull and a propulsion unit. The propulsion unit comprises a hollow strut rotatably attached to the hull of the vessel, a propeller shaft having an axial centre line and being positioned and supported in the lower portion of the strut with bearings, a propeller being attached to at least one end of the propeller shaft protruding from the lower portion of the strut, and an electric motor driving the propeller shaft. An additional support arrangement is positioned at least in one end portion of the propeller shaft axially outwards from the bearings. The support arrangement comprises a first support surface formed in connection with the propeller shaft and a second support surface mating with the first support surface and being formed in connection with the lower portion of the strut. The second support surface is positioned at a predetermined distance from the first support surface so that a slot is formed between the first support surface and the second support surface facing towards each other. The being of the propeller shaft due to external loads acting on the propeller is restricted to a predetermined maximum value with the support surfaces.

1 . A vessel with a hull and a propulsion unit, the propulsion unit comprising:
 a hollow strut with an upper portion and a lower portion, the upper portion being rotatably attached to the hull of the vessel and forming a support arm for the lower portion, the lower portion forming a longitudinal compartment having a first end and a second opposite end,   a propeller shaft having an axial centre line (X-X) and being positioned within the lower portion of the strut and supported in the lower portion of the strut with bearings positioned at an axial (X-X) distance from each other,   a propeller being attached to at least one end of the propeller shaft protruding from the lower portion of the strut,   a motor driving the propeller shaft,   an additional support arrangement being positioned at least in one end portion of the propeller shaft axially (X-X) outwards from the bearings, said support arrangement comprising:
 a first support surface formed in connection with the propeller shaft or in connection with a part attached to the propeller shaft so that the first support surface rotates with the propeller shaft, 
 a second support surface mating with the first support surface and being formed in connection with the lower portion of the strut or in connection with a part attached to the lower portion of the strut so that the second support surface is stationary in relation to the rotating propeller shaft, 
 the second support surface being positioned at a predetermined distance from the first support surface so that a slot (S 1 ) is formed between the first support surface and the second support surface facing towards each other, whereby 
 the bending of the propeller shaft due to external loads acting on the propeller is restricted to a predetermined maximum value with the support surface. 
   
     
     
         2 . The vessel according to  claim 1 , wherein a bearing point is formed between said support surfaces when the propeller shaft bends due to external loads acting on the propeller so that said support surfaces make contact with each other, said support surfaces restricting the bending of the propeller shaft to a predetermined maximum value. 
     
     
         3 . The vessel according to  claim 1 , wherein the slot is open to sea water so that the first support surface and the second support surface become water lubricated. 
     
     
         4 . The vessel according to  claim 1 , wherein the first support surface is formed on a propeller hub of the propeller and the second support surface is formed on a stationary part attached to the strut opposite to the first support surface. 
     
     
         5 . The vessel according to  claim 1 , wherein the first support surface is formed in connection with an opposite end of the propeller shaft in relation to the propeller, and the second support surface is formed on a stationary part attached to the strut opposite to the first support surface. 
     
     
         6 . The vessel according to  claim 1 , wherein both support surfaces are cylindrical and coaxial with the axial centre line (X-X) of the shaft, whereby the slot (S 1 ) between the support surfaces has a width (W 1 ) in the axial (X-X)-direction and a depth (D 1 )-in the radial direction. 
     
     
         7 . The vessel according to  claim 1 , wherein one support surfaces is cylindrical and coaxial with the axial centre line (X-X) of the shaft or slightly conical and the other support surface is slightly conical, whereby the slot (S 1 ) between the support surfaces has a width (W 1 )-in the axial (X-X)-direction and a varying depth (D 1 ) in the radial direction. 
     
     
         8 . The vessel according to  claim 1 , wherein both support surfaces form a ring in the radial plane, whereby the slot (S 1 )-between the support surfaces has a width (W 1 )-in the radial direction and a depth (D 10  in the axial (X-X)-direction. 
     
     
         9 . The vessel according to  claim 1 , wherein both support surfaces form a ring in the radial plane and that one support surface is slightly inclined in relation to the other support surface or that both support surfaces are slightly inclined in the same direction, whereby the slot (S 1 ) between the support surfaces has a width (W 1 ) in the radial direction and a varying depth (D 1 ) in the axial (X-X) direction. 
     
     
         10 . The vessel according to  claim 1 , wherein the first support surface and the second support surface are situated axially (X-X) outwardly in relation to the bearing of the propeller shaft that is closest to the propeller hub. 
     
     
         11 . The vessel according to  claim 1 , wherein the motor is an electric motor positioned in the lower portion of the strut, whereby the propeller shaft passes through the electric motor. 
     
     
         12 . The vessel according to  claim 11 , wherein the propeller shaft is supported with two bearings within the strut, whereby a first bearing is positioned on the propeller shaft between the electric motor and the propeller hub and a second bearing is positioned on the propeller shaft at the axially (X-X) opposite side of the electric motor. 
     
     
         13 . The vessel according to  claim 12 , wherein the second bearing is a combined radial and thrust bearing. 
     
     
         14 . The vessel according to  claim 1 , wherein the motor is an electric motor positioned in the upper portion of the strut, whereby a second shaft passes through the electric motor, said second shaft being connected via a transmission to the propeller shaft. 
     
     
         15 . The vessel according to  claim 1 , wherein the support surfaces are positioned radially outwards from the outer surface of the propeller shaft. 
     
     
         16 . The vessel according to  claim 1 , wherein one of the support surfaces is made of a softer material compared to the other support surface. 
     
     
         17 . A method in a vessel with a hull and a propulsion unit, the propulsion unit comprising:
 a hollow strut with an upper portion and a lower portion, the upper portion being rotatably attached to the hull of the vessel and forming a support arm for the lower portion, the lower portion forming a longitudinal compartment having a first end and a second opposite end,   a propeller shaft having an axial centre line (X-X) and being positioned within the lower portion of the strut and supported in the lower portion of the strut with bearings positioned at an axial (X-X)-distance from each other,   a propeller being attached to at least one end of the propeller shaft protruding from the lower portion of the strut,   a motor driving the propeller shaft,   an additional support arrangement being positioned at least in one end portion of the propeller shaft (X-X)-axially outwards from the bearings, said support arrangement comprising:   a first support surface formed in connection with the propeller shaft or in connection with a part attached to the propeller shaft so that the first support surface rotates with the propeller shaft,   a second support surface mating with the first support surface and being formed in connection with the lower portion of the strut or in connection with a part attached to the lower portion of the strut so that the second support surface is stationary in relation to the rotating propeller shaft,   the method comprising:
 positioning the second support surface at a predetermined distance from the first support surface so that a slot (S 1 ) is formed between the first support surface and the second support surface facing towards each other, 
 restricting the bending of the propeller shaft caused by external loads acting on the propeller to a predetermined maximum value with the support surfaces, said maximum value being defined by the predetermined distance between the support surfaces. 
   
     
     
         18 . The method according to  claim 17 , further comprising arranging the slot (S 1 ) to be open to sea water so that the first support surface and the second support surface become water lubricated. 
     
     
         19 . The method according to  claim 17 , further comprising forming the first support surface on a propeller hub of the propeller and forming the second support surface on a stationary part attached to the strut opposite to the first support surface. 
     
     
         20 . The method according to  claim 17 , further comprising forming the first support surface in connection with an opposite end of the propeller shaft in relation to the propeller, and forming the second support surface y on a stationary part attached to the strut opposite to the first support surface. 
     
     
         21 . The method according to  claim 17 , further comprising forming both support surfaces cylindrical and coaxial with the axial centre line (X-X) of the shaft, whereby the slot (S 1 )-between the support surfaces has a width (W 1 ) in the axial (X-X) direction and a depth (D 1 )-in the radial direction. 
     
     
         22 . The method according to  claim 17 , further comprising forming one support surfaces cylindrical and coaxial with the axial centre line (X-X) of the shaft or slightly conical and forming the other support surface slightly conical, whereby the slot (S 1 ) between the support surfaces has a width (W 1 ) in the axial (X-X) direction and a varying depth (D 1 )-in the radial direction. 
     
     
         23 . The method according to in  claim 17 , further comprising forming both support surfaces as a ring in the radial plane, whereby the slot (S 1 ) between the support surfaces has a width (W 1 ) in the radial direction and a depth (D 1 ) in the axial (X-X) direction. 
     
     
         24 . The method according to  claim 17 , further comprising forming both support surfaces as a ring in the radial plane and forming one support surface slightly inclined in relation to the other support surface or forming both support surfaces slightly inclined in the same direction, whereby the slot (S 1 ) between the support surfaces has a width (W 1 ) in the radial direction and a varying depth (D 1 ) in the axial (X-X)-direction. 
     
     
         25 . The method according to  claim 17 , further comprising positioning the first support surface and the second support surface axially (X-X) outwardly in relation to the bearing of the propeller shaft that is closest to the propeller hub. 
     
     
         26 . The method according to  claim 17 , further comprising positioning the motor being an electric motor in the lower portion of the strut, whereby the propeller shaft passes through the electric motor. 
     
     
         27 . The method according to  claim 26 , further comprising supporting the propeller shaft with two bearings within the strut, whereby a first bearing is positioned on the propeller shaft between the electric motor and the propeller hub and a second bearing is positioned on the propeller shaft at the axially (X-X) opposite side of the electric motor. 
     
     
         28 . The method according to  claim 27 , further comprising providing the second bearing as a combined radial and thrust bearing. 
     
     
         29 . The method according to  claim 17 , further comprising positioning the motor being an electric motor in the upper portion of the strut, whereby a second shaft passes through the electric motor, said second shaft being connected via a transmission to the propeller shaft. 
     
     
         30 . The method according to  claim 17 , further comprising positioning the support surfaces radially outwards from the outer surface of the propeller shaft. 
     
     
         31 . The method according to  claim 17 , further comprising providing one of the support surfaces with a softer material compared to the other support surface.