Ship's propulsion unit

Abstract

The disclosure relates to a ship's propulsion unit including a shell structure arranged below a hull of the ship and an electric motor for rotating a propeller. The propulsion unit can include a closed gas circulation cooling system containing gas and include a gas circulation device for circulating gas through channels in the electric motor, a closed liquid cooling system having an inner space containing liquid, and a gas-liquid-heat exchanger in fluid connection with the closed gas circulation cooling system and with the closed liquid cooling system for exchanging thermal energy between gas circulating in the closed gas circulation cooling system and liquid in the closed liquid cooling system.

1 . A ship propulsion unit, comprising:
 a shell structure configured to be arranged below a hull of a ship and immersible at least partly in water so that the shell structure will be at least partly surrounded by water in use; and   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 an lower end connected to the motor housing section of the shell structure and an upper end for connection to a hull of a ship;   a closed gas circulation cooling system containing gas and having gas circulation means for circulating gas through channels in the electric motor,   a closed liquid cooling system having an inner space containing liquid; and   a gas-liquid-heat exchanger in fluid connection with the closed gas circulation cooling system and in fluid connection with the closed liquid cooling system for exchanging thermal energy between gas circulating in the closed gas circulation cooling system and liquid in the closed liquid cooling system, the closed gas circulation cooling system, the closed liquid cooling system, and the gas-liquid-heat exchanger being parts of the propulsion unit.   
     
     
         2 . The propulsion unit according to  claim 1 , wherein 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 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 closed liquid cooling system and water surrounding the propulsion unit via the shell structure of the propulsion unit. 
     
     
         3 . 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 an opening for allowing water surrounding the propulsion unit to flow through the opening in the shell structure is formed in the support section of the shell structure. 
     
     
         4 . The propulsion unit according to  claim 3 , 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 opening in the support section of the shell structure is formed between the support section of the shell structure and the motor housing section of the shell structure, and so that a cylindrical part of the cylindrical outer surface of the cylindrical section of the motor housing section forms a part of an outermost surface of the propulsion unit, which outermost surface is configured to be at least partly in contact with water surrounding the propulsion unit. 
     
     
         5 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is a closed liquid tank forming said inner space containing liquid. 
     
     
         6 . The propulsion unit according to  claim 5 , wherein the closed liquid tank is partly limited by the cylindrical outer surface of the cylindrical section of the motor housing section so that liquid in the closed 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 electrical motor arranged in the cylindrical section of the motor housing section and liquid in the closed liquid tank via the cylindrical section of the motor housing section. 
     
     
         7 . The propulsion unit according to  claim 5 , wherein the closed liquid tank is partly limited by the support section of the shell structure of the propulsion unit so that liquid in the closed liquid tank will be in direct contact with the support section of the shell structure of the propulsion unit for exchanging thermal energy between liquid in the closed liquid tank and water surrounding the support section of the shell structure of the propulsion unit via the shell structure of the propulsion unit. 
     
     
         8 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is a closed liquid circulation cooling system containing liquid and forming said inner space containing liquid, and is provided with liquid circulation means for circulating liquid in the inner space of the closed liquid circulation cooling system. 
     
     
         9 . The propulsion unit according to  claim 8 , wherein the closed liquid circulation cooling system is partly formed by a tube section having an outer surface that is will be in direct contact with water surrounding the propulsion unit for exchanging thermal energy between liquid circulating in the closed liquid circulation cooling system and water surrounding the propulsion unit via the tube section of the closed liquid circulation cooling system. 
     
     
         10 . The propulsion unit according to  claim 9 , wherein the tube section is a part of a liquid-liquid-heat exchanger that is in fluid communication with the closed liquid cooling system so that liquid circulating in the inner space of the closed liquid cooling system will circulate through the tube section of the liquid-liquid-heat exchanger for exchanging thermal energy between liquid which flows through the tube section of the liquid-liquid-heat exchanger and water in contact with the tube section of the liquid-liquid-heat exchanger and surrounding the shell structure of the propulsion unit. 
     
     
         11 . The propulsion unit according to  claim 8 , wherein the inner space of the closed liquid circulation cooling system is 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 flowing 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. 
     
     
         12 . The propulsion unit according to  claim 8 , wherein the inner space of the closed liquid circulation cooling system is 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. 
     
     
         13 . The propulsion unit according to  claim 12 , 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. 
     
     
         14 . The propulsion unit according to  claim 8 , wherein the closed liquid circulation cooling system is provided with a first liquid tank;
 wherein the first liquid tank has 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   wherein the first inner space of the first liquid tank is 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 is 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.   
     
     
         15 . The propulsion unit according to  claim 14 , wherein the first liquid tank is additionally partly limited by the support section 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 section 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 section of the shell structure via the support section of the shell structure. 
     
     
         16 . The propulsion unit according to  claim 8 , wherein the closed liquid circulation cooling system is provided with a second liquid tank, wherein the second liquid tank has 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
 wherein the second liquid tank is 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 flowing 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.   
     
     
         17 . The propulsion unit according to  claim 8 , wherein the gas-liquid-heat exchanger is a separate heat exchanger in fluid connection with the closed gas circulation cooling system and in fluid connection with the closed liquid cooling system for exchanging thermal energy between gas circulating in the closed gas circulation cooling system and liquid in the closed liquid cooling system. 
     
     
         18 . 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, which outermost surface is configured to be at least partly in contact with water surrounding the propulsion unit. 
     
     
         19 . The propulsion unit according to  claim 1 , wherein the cylindrical section of the motor housing section is of a single-layer construction. 
     
     
         20 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is arranged at least partly enclosed by the shell structure of the propulsion unit, wherein the closed gas circulation cooling system is arranged at least partly enclosed by the shell structure of the propulsion unit, and wherein the gas-liquid-heat exchanger is arranged at least partly enclosed by the shell structure of the propulsion unit. 
     
     
         21 . The propulsion unit according to  claim 1 , wherein the closed liquid cooling system is configured to be arranged fully outside a hull of a ship, wherein the closed gas circulation cooling system is configured to be arranged fully outside the hull of the ship, and wherein the gas-liquid-heat exchanger is configured to be arranged fully outside the hull of the ship.