Marine propulsion device

Abstract

A marine propulsion device for propelling a boat is provided The marine propulsion device includes a motor including an output shaft, a drive shaft configured to rotate upon receiving a rotation of the output shaft, a propeller shaft provided with a propeller and configured to be rotated upon receiving a rotation of the drive shaft, and a cooling device. The cooling device includes a cooling mechanism configured to cool the motor, and a water pump configured to send water outside the marine propulsion device to the cooling mechanism. An impeller of the water pump is connected via a one-way clutch to the output shaft, the drive shaft, or a rotation transmission member other than the drive shaft provided in the marine propulsion device and configured to rotate by the rotation of the output shaft.

What is claimed is: 
     
         1 . A marine propulsion device for propelling a boat, the marine propulsion device comprising: 
 a motor including an output shaft;   a drive shaft configured to rotate upon receiving a rotation of the output shaft;   a propeller shaft provided with a propeller and configured to be rotated upon receiving a rotation of the drive shaft; and   a cooling device, wherein   the cooling device includes    a cooling mechanism configured to cool the motor, and    a water pump configured to send water outside the marine propulsion device to the cooling mechanism, and   an impeller of the water pump is connected via a one-way clutch to the output shaft, the drive shaft, or a rotation transmission member other than the drive shaft provided in the marine propulsion device and configured to rotate by the rotation of the output shaft.   
     
     
         2 . The marine propulsion device according to  claim 1 , wherein the impeller is attached to a shaft, the shaft being attached to the output shaft, the drive shaft, or the rotation transmission member via the one-way clutch. 
     
     
         3 . The marine propulsion device according to  claim 1 , wherein the impeller is attached to the output shaft, the drive shaft, or the rotation transmission member via the one-way clutch. 
     
     
         4 . The marine propulsion device according to  claim 1 , wherein 
       the motor is disposed so that an extension direction of the output shaft is a vertical direction, 
       a transmission shaft disposed coaxially with the output shaft, below the output shaft, and extending in the vertical direction is connected to the output shaft via the one-way clutch, and 
       the impeller is attached to the transmission shaft. 
     
     
         5 . The marine propulsion device according to  claim 1 , wherein 
       the motor is disposed so that an extension direction of the output shaft is a vertical direction, 
       a gear configured to transmit the rotation of the output shaft to the drive shaft is attached to the output shaft, 
       a transmission shaft disposed coaxially with the output shaft and extending downward from the gear is attached to the gear via the one-way clutch, and 
       the impeller is attached to the transmission shaft. 
     
     
         6 . The marine propulsion device according to  claim 1 , wherein 
       a transmission shaft having a cylindrical shape and coaxial with the drive shaft is provided on an outer periphery of the drive shaft, 
       the transmission shaft is attached to the outer periphery of the drive shaft via the one-way clutch, and 
       the impeller is attached to the transmission shaft. 
     
     
         7 . The marine propulsion device according to  claim 1 , wherein the impeller is made of rubber. 
     
     
         8 . The marine propulsion device according to  claim 1 , wherein 
        the cooling mechanism includes 
        a heat exchanger configured to cool refrigerant by using water outside the marine propulsion device as cooling water, 
        a motor cooling jacket provided in the motor and configured to cool the motor using the refrigerant, and 
        a circulation passage configured to circulate the refrigerant between the heat exchanger and the motor cooling jacket.