Electric propulsion device

Abstract

An electric propulsion device includes a motor configured to rotate a propeller, a propeller shaft disposed below the motor and provided with the propeller in a rear part, a lower case accommodating a front part of the propeller shaft, and a cooling device configured to cool the motor. The cooling device includes a heat exchanger configured to cool refrigerant by using water outside the electric propulsion device as cooling water, a motor cooling jacket provided in the motor and configured to cool the motor by using the refrigerant, and a circulation passage configured to circulate the refrigerant between the heat exchanger and the motor cooling jacket. The heat exchanger is provided in the lower case.

What is claimed is: 
     
         1 . An electric propulsion device comprising: 
 a motor configured to rotate a propeller;   a propeller shaft disposed below the motor and provided with the propeller in a rear part;   a lower case accommodating a front part of the propeller shaft; and   a cooling device configured to cool the motor, wherein   the cooling device includes    a heat exchanger configured to cool refrigerant by using water outside the electric propulsion device as cooling water,    a motor cooling jacket provided in the motor and configured to cool the motor by using the refrigerant, and    a circulation passage configured to circulate the refrigerant between the heat exchanger and the motor cooling jacket, and   the heat exchanger is provided in the lower case.   
     
     
         2 . The electric propulsion device according to  claim 1 , wherein the heat exchanger is provided on an outer circumferential side of the propeller shaft in the lower case. 
     
     
         3 . The electric propulsion device according to  claim 2 , wherein the heat exchanger includes a cooling water passage in which the cooling water flows in an axial direction of the propeller shaft, and a refrigerant passage in which the refrigerant flows in a circumferential direction of the propeller shaft. 
     
     
         4 . The electric propulsion device according to  claim 3 , wherein the cooling water passage includes a plurality of cooling tubes in which the cooling water flows, and each of the cooling tubes is disposed to pass in the refrigerant flowing in the refrigerant passage. 
     
     
         5 . The electric propulsion device according to  claim 3 , wherein  
       a propeller shaft accommodating hole extending in a front-rear direction is provided in a lower part of the lower case,  
       a shaft housing having a cylindrical shape and supporting the propeller shaft to be rotatable is provided in the propeller shaft accommodating hole, and  
       the cooling water passage and the refrigerant passage are provided between the propeller shaft accommodating hole and the shaft housing. 
     
     
         6 . The electric propulsion device according to  claim 5 , wherein 
       a space between the propeller shaft accommodating hole and the propeller shaft is divided by the shaft housing into a cooling water inlet chamber positioned in a front part of the space, a refrigerant flow chamber positioned in a front-rear middle part of the space, and a cooling water outlet chamber positioned in a rear part of the space,  
       the refrigerant passage is formed in the refrigerant flow chamber,  
       an inlet side end of the cooling water passage communicates with the cooling water inlet chamber,  
       an outlet side end of the cooling water passage communicates with the cooling water outlet chamber, and  
       the cooling water passage passes through the refrigerant flow chamber without communicating with inside of the refrigerant flow chamber. 
     
     
         7 . The electric propulsion device according to  claim 6 , wherein 
       the cooling device includes an intake port configured to take water outside the electric propulsion device into the electric propulsion device, and an intake passage connecting the intake port to the cooling water inlet chamber, 
       the intake port is provided in a front part of a portion where the lower case and a skeg are coupled to each other, and 
       the intake passage extends in the front-rear direction between the lower case and the skeg. 
     
     
         8 . The electric propulsion device according to  claim 6 , wherein 
       the cooling device includes an axial flow impeller configured to rotate integrally with the propeller shaft, 
       the cooling water outlet chamber communicates with inside of a hub of the propeller, and 
       the axial flow impeller is disposed in the cooling water outlet chamber, between the cooling water outlet chamber and the hub of the propeller, or in the hub of the propeller. 
     
     
         9 . The electric propulsion device according to  claim 6 , wherein a baffle plate is provided in the refrigerant flow chamber so that the refrigerant flows in a zigzag shape in the refrigerant flow chamber. 
     
     
         10 . The electric propulsion device according to  claim 1 , wherein 
        the cooling device includes two heat exchangers, and 
        one of the two heat exchangers is provided on an outer circumferential side of the propeller shaft in the lower case, and the other one of the two heat exchangers is provided above the propeller shaft in the lower case.