Ship's propulsion unit

Abstract

The present disclosure relates to a ship's propulsion unit which includes: a closed liquid cooling system having an inner space containing liquid. The inner space is partly limited by a cylindrical outer surface of a cylindrical section of a motor housing section of the propulsion unit for exchanging thermal energy between an electric motor arranged in the cylindrical section of the motor housing section and liquid in the inner space. The inner space of the closed liquid cooling system is partly limited by the shell structure of the propulsion unit so that liquid in the inner space is in direct contact with the shell structure of the propulsion unit for exchanging thermal energy between liquid in the inner space and water surrounding the propulsion unit via the shell structure of the propulsion unit.

1 . A ship's propulsion unit, comprising:
 a shell structure configured to be arranged below a hull of the ship and immersible at least partly in water so that the shell structure will be at least partly surrounded by water;   an electric motor for rotating a propeller outside the shell structure, the electric motor having a stator and a rotor for rotating in the stator;   wherein the electric motor is arranged in a motor housing section of the shell structure so that the stator of the electric motor is form-fitted into a cylindrical section of the motor housing section of the shell structure; the cylindrical section having a cylindrical outer surface; and   wherein the shell structure includes a support section having a lower end connected to the motor housing section of the shell structure and an upper end connected to the hull of the ship;   a closed liquid cooling system having an inner space containing liquid, the inner space of the closed liquid cooling system being partly limited by the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid in the inner space of the closed liquid cooling system will be in direct contact with the cylindrical outer surface of the cylindrical section of the motor housing section for exchanging thermal energy between the electric motor arranged in the cylindrical section of the motor housing section and liquid in the inner space of the closed liquid cooling system via the cylindrical section of the motor housing section; and   the inner space of the closed liquid cooling system being partly limited by the shell structure of the propulsion unit so that liquid in the inner space of the closed liquid cooling system will be in direct contact with the shell structure of the propulsion unit for exchanging thermal energy between liquid in the inner space of the closed liquid cooling system and water surrounding the propulsion unit via the shell structure of the propulsion unit.   
     
     
         2 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is a closed liquid tank forming said inner space containing liquid, the inner space of the closed liquid tank being partly limited by a part of the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid in the inner space of the closed liquid tank will be in direct contact with said part the cylindrical outer surface of the cylindrical section of the motor housing section for exchanging thermal energy between the electric motor arranged in the cylindrical section of the motor housing section and liquid in the inner space of the closed liquid tank via said part of the cylindrical section of the motor housing section between the electric motor and liquid in the inner space of the closed liquid tank; and
 the inner space of the closed liquid tank being partly limited by the shell structure of the propulsion unit so that liquid in the inner space of the closed liquid tank will be in direct contact with the shell structure for exchanging thermal energy between liquid in the inner space of the closed liquid tank and water surrounding the shell structure via the shell structure.   
     
     
         3 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is a closed liquid circulation cooling system having said inner space containing liquid and provided with liquid circulation means for circulating liquid in the inner space of the closed liquid circulation cooling system, the inner space of the closed liquid circulation cooling system being partly limited by a part of the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid which flows in the inner space of the closed liquid circulation cooling system will be in direct contact with said part of the cylindrical outer surface of the cylindrical section of the motor housing section for exchanging thermal energy between the electric motor arranged in the cylindrical section of the motor housing section and liquid which flows in the inner space of the closed liquid circulation cooling system via said part of the cylindrical section of the motor housing section between the electric motor and liquid circulating in the inner space of the closed liquid circulation cooling system; and
 the inner space of the closed liquid circulation cooling system being additionally partly limited by the support section of the shell structure of the propulsion unit so that liquid which flows in the inner space of the closed liquid circulation cooling system will be in direct contact with the support section of the shell structure for exchanging thermal energy between liquid which flows in the inner space of the closed liquid circulation cooling system and water surrounding the support section of the shell structure via the support section of the shell structure.   
     
     
         4 . The propulsion unit according to  claim 3 , wherein said part of the cylindrical outer surface of the cylindrical section of the motor housing section in contact with liquid in the inner space of the closed liquid circulation cooling system is provided with partition elements for creating several individual flows of liquid along said part of the cylindrical outer surface of the cylindrical section of the motor housing section. 
     
     
         5 . The propulsion unit according to  claim 3 , wherein the closed liquid circulation cooling system is provided with a first liquid tank at a point of the closed liquid circulation cooling system where the inner space of the closed liquid circulation cooling system is partly limited by said part of the cylindrical outer surface of the cylindrical section of the motor housing section, the first liquid tank having a first inner space that forms a part of the inner space of the closed liquid circulation cooling system;
 the first liquid tank being in fluid communication with the closed liquid circulation cooling system such that liquid which flows in the closed liquid circulation cooling system will flow through the first inner space of the first liquid tank; and   the first inner space of the first liquid tank being partly limited by said part of the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid in a first inner space of the first liquid tank will be in direct contact with the cylindrical outer surface of the cylindrical section of the motor housing section for exchanging thermal energy between the electric motor arranged in the motor housing section and liquid which flows in the first inner space of the first liquid tank via said part of the cylindrical outer surface of the cylindrical section of the motor housing section.   
     
     
         6 . The propulsion unit according to  claim 5 , wherein the first liquid tank is additionally partly limited by the support structure of the shell structure so that liquid in the first inner space of the first liquid tank will be additionally in direct contact with the support structure of the shell structure for exchanging thermal energy between liquid which flows in the first inner space of the first liquid tank of the closed liquid circulation cooling system and water surrounding the support structure of the shell structure via the support structure of the shell structure. 
     
     
         7 . The propulsion unit according to  claim 3 , wherein the closed liquid circulation cooling system is provided with a second liquid tank at a point of the closed liquid circulation cooling system where the closed liquid circulation cooling system is partly limited by the support section of the shell structure so that the second liquid tank is partly limited by the support section of the shell structure, the second liquid tank having a second inner space that forms a part of the inner space of the closed liquid circulation cooling system;
 the second liquid tank being in fluid communication with the closed liquid circulation cooling system such that liquid which flows in the closed liquid circulation cooling system will flow through the second inner space of the second liquid tank; and   the second liquid tank being partly limited by the support section of the shell structure so that liquid in the second inner space of the second liquid tank will be in direct contact with the support section of the shell structure for exchanging thermal energy between liquid which flows in the second inner space of the second liquid tank and water surrounding the support section of the shell structure via the support section of the shell structure.   
     
     
         8 . The propulsion unit according to  claim 3 , wherein the support section of the shell structure is provided with a cavity in fluid communication with water surrounding the shell structure for allowing water surrounding the shell structure to enter the cavity and to exit the cavity;
 the closed liquid circulation cooling system comprising a tube section;   the inner space of the closed liquid circulation cooling system being partly limited by the tube section; and   the tube section being arranged in the cavity so that an outer surface of the tube section will be in the cavity in direct contact with water surrounding the shell structure.   
     
     
         9 . The propulsion unit according to  claim 8 , wherein the tube section is a part of a liquid-liquid-heat exchanger for exchanging thermal energy between liquid in the inner space of the closed liquid circulation cooling system and water surrounding the shell structure; and
 said liquid-liquid-heat exchanger is arranged in the cavity.   
     
     
         10 . The propulsion unit according to  claim 8 , wherein the cavity is at least partly closed by at least one cover forming a part of the shell structure. 
     
     
         11 . The propulsion unit according to  claim 1 , wherein the lower end of the support section of the shell structure is connected to the motor housing section of the shell structure so that the cylindrical outer surface of the cylindrical section of the motor housing section of the shell structure of the propulsion unit partly forms the outermost surface of the propulsion unit. 
     
     
         12 . The propulsion unit according to  claim 11 , wherein the part of the cylindrical outer surface of the cylindrical section of the motor housing section forming the outermost surface of the propulsion unit is provided with projecting heat-exchanging elements for enhancing transfer of thermal energy between the electric motor in the motor housing section and water surrounding the part of the cylindrical outer surface of the cylindrical section of the motor housing section forming the outermost surface of the propulsion unit. 
     
     
         13 . The propulsion unit according to  claim 1 , wherein by the cylindrical section of the motor housing section is of a single-layer construction 
     
     
         14 . The propulsion unit according to  claim 1 , wherein the part of the cylindrical section of the cylindrical outer surface of the motor housing section in contact with liquid in the closed liquid cooling system is provided with projecting heat-exchanging elements for enhancing transfer of thermal energy between the electric motor in the motor housing section and liquid in the closed liquid cooling system. 
     
     
         15 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is arranged fully enclosed by the shell structure of the propulsion unit. 
     
     
         16 . The propulsion unit according to  claim 1 , wherein the electric motor is a permanent-magnet electric motor. 
     
     
         17 . The propulsion unit according to  claim 4 , wherein the closed liquid circulation cooling system is provided with a first liquid tank at a point of the closed liquid circulation cooling system where the inner space of the closed liquid circulation cooling system is partly limited by said part of the cylindrical outer surface of the cylindrical section of the motor housing section, the first liquid tank having a first inner space that forms a part of the inner space of the closed liquid circulation cooling system;
 the first liquid tank being in fluid communication with the closed liquid circulation cooling system such that liquid which flows in the closed liquid circulation cooling system will flow through the first inner space of the first liquid tank; and   the first inner space of the first liquid tank being partly limited by said part of the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid in a first inner space of the first liquid tank will be in direct contact with the cylindrical outer surface of the cylindrical section of the motor housing section for exchanging thermal energy between the electric motor arranged in the motor housing section and liquid which flows in the first inner space of the first liquid tank via said part of the cylindrical outer surface of the cylindrical section of the motor housing section.   
     
     
         18 . The propulsion unit according to  claim 4 , wherein the closed liquid circulation cooling system is provided with a second liquid tank at a point of the closed liquid circulation cooling system where the closed liquid circulation cooling system is partly limited by the support section of the shell structure so that the second liquid tank is partly limited by the support section of the shell structure, the second liquid tank having a second inner space that forms a part of the inner space of the closed liquid circulation cooling system;
 the second liquid tank being in fluid communication with the closed liquid circulation cooling system such that liquid which flows in the closed liquid circulation cooling system will flow through the second inner space of the second liquid tank; and   the second liquid tank being partly limited by the support section of the shell structure so that liquid in the second inner space of the second liquid tank will be in direct contact with the support section of the shell structure for exchanging thermal energy between liquid which flows in the second inner space of the second liquid tank and water surrounding the support section of the shell structure via the support section of the shell structure.   
     
     
         19 . The propulsion unit according to  claim 4 , wherein the support section of the shell structure is provided with a cavity in fluid communication with water surrounding the shell structure for allowing water surrounding the shell structure to enter the cavity and to exit the cavity;
 the closed liquid circulation cooling system comprising a tube section;   the inner space of the closed liquid circulation cooling system being partly limited by the tube section; and   the tube section being arranged in the cavity so that an outer surface of the tube section will be in the cavity in direct contact with water surrounding the shell structure.   
     
     
         20 . The propulsion unit according to  claim 9 , wherein the cavity is at least partly closed by at least one cover forming a part of the shell structure.