Marine Propulsion Devices, Systems and Methods

Abstract

Some embodiments provide a propulsion system for a marine vessel that includes an electric motor-generator coupled between an internal combustion engine and a propeller through one or more clutches. The propulsion system includes a controller configured to adjust a torque load of the electric motor-generator based on factors such as rotational speed, propeller torque, and/or a peak torque output of the internal combustion engine. Some embodiments provide a propulsion assembly component including an electric motor-generator that can be installed in an existing marine propulsion system. Embodiments also provide methods for propelling a marine vessel.

1 . A propulsion system for a marine vessel, comprising:
 an internal combustion engine;   a first clutch operatively coupled to the internal combustion engine;   an electric motor-generator operatively coupled to the first clutch;   an output shaft operatively coupled to the internal combustion engine through the first clutch, operatively coupled to the electric motor-generator and configured to be operatively coupled to a propeller shaft; and   a controller electrically coupled to the internal combustion engine and the electric motor-generator, the controller configured to adjust a torque load of the electric motor-generator based on a rotational speed of the internal combustion engine and a peak torque output of the internal combustion engine corresponding to the rotational speed.   
     
     
         2 . The propulsion system of  claim 1 , wherein the controller is further configured to adjust the torque load of the electric motor-generator to load the internal combustion engine with a torque that is within about 30% of the peak torque output corresponding to the rotational speed. 
     
     
         3 . The propulsion system of  claim 1 , wherein the controller is further configured to adjust the torque load of the electric motor-generator to load the internal combustion engine with a torque that is within about 10% of the peak torque output corresponding to the rotational speed. 
     
     
         4 . The propulsion system of  claim 1 , wherein the controller is further configured to adjust the torque load of the electric motor-generator to load the internal combustion engine with a torque that is substantially the same as the peak torque output corresponding to the rotational speed. 
     
     
         5 . The propulsion system of  claim 1 , wherein the controller is further configured to adjust the torque load of the electric motor-generator based on a propeller torque load. 
     
     
         6 . The propulsion system of  claim 5 , further comprising a propeller shaft operatively coupled to the output shaft and a propeller operatively coupled to the propeller shaft, wherein the propeller torque load corresponds to a torque load of the propeller at the rotational speed. 
     
     
         7 . The propulsion system of  claim 6 , wherein the propeller is a variable pitch propeller and the controller is further configured to adjust a pitch of the propeller's blades. 
     
     
         8 . The propulsion system of  claim 6 , further comprising a second clutch operatively coupled between the electric motor-generator and the output shaft for disengaging the output shaft, the propeller shaft, and the propeller from the electric motor-generator and the internal combustion engine. 
     
     
         9 . The propulsion system of  claim 8 , wherein the controller is further configured to provide at least three operational configurations comprising
 a first configuration in which the first clutch is engaged and the second clutch is disengaged, to generate electricity with the internal combustion engine and the electric motor-generator,   a second configuration in which the first clutch is disengaged and the second clutch is engaged, for driving the propeller with only the electric motor-generator, and   a third configuration in which the first clutch is engaged and the second clutch is engaged, for driving the propeller with the internal combustion engine and/or the electric motor-generator.   
     
     
         10 . The propulsion system of  claim 1 , wherein the controller comprises a computer-readable storage medium storing information characterizing the peak torque output of the internal combustion engine for a plurality of rotational speeds. 
     
     
         11 . The propulsion system of  claim 1 , wherein the output shaft is rotatable by the internal combustion engine in only a first direction, and the output shaft is rotatable by the electric motor-generator in the first direction and a second direction. 
     
     
         12 . The propulsion system of  claim 1 , further comprising at least one battery electrically coupled to the electric motor-generator, and wherein the controller is further configured to operate the electric motor-generator with the battery, start the internal combustion engine to charge the battery when the battery reaches a first charge level, and stop the internal combustion engine when the battery reaches a second charge level. 
     
     
         13 . The propulsion system of  claim 1 , wherein the controller is further configured to start the internal combustion engine when a vessel propelled by the propulsion system is moving faster than a first speed and to stop the internal combustion engine when the vessel is moving slower than the first speed. 
     
     
         14 . The propulsion system of  claim 1 , wherein the controller is further configured to adjust the torque load of the electric motor-generator by adjusting a value of a charging current of the electric motor-generator. 
     
     
         15 . The propulsion system of  claim 1 , further comprising a battery and at least one renewable energy source electrically coupled to the controller, wherein the controller is further configured to combine a charging current of the electric motor-generator with a charging current of the at least one renewable energy source to charge the battery, and wherein the controller is further configured to reduce the charging current of the electric motor-generator, as a charge level of the battery increases, before reducing the charging current of the at least one renewable energy source. 
     
     
         16 . A method for propelling a marine vessel, comprising:
 determining with control circuitry a desired torque output of an internal combustion engine, the internal combustion engine being operatively coupled to an electric motor-generator and a propeller;   determining with the control circuitry a current torque output;   determining a torque output change by comparing the desired torque output to the current torque output with the control circuitry; and   adjusting a torque load of the electric motor-generator with the control circuitry based on the torque output change.   
     
     
         17 . The method of  claim 16 , wherein the desired torque output is a peak torque output of the internal combustion engine for a rotational speed. 
     
     
         18 . The method of  claim 16 , wherein determining the current torque output comprises determining a torque load of the propeller. 
     
     
         19 . The method of  claim 18 , wherein the propeller comprises a plurality of variable pitch blades, and further comprising adjusting the pitch of the plurality of variable pitch blades to adjust the torque load of the propeller. 
     
     
         20 . The method of  claim 16 , further comprising charging a battery with a charge current produced by the electric motor-generator. 
     
     
         21 . The method of  claim 20 , further comprising charging the battery with a charge current produced by a renewable energy source and reducing the charging with the electric motor-generator charge current to maximize the charging with the renewable energy source charge current. 
     
     
         22 . The method of  claim 16 , further comprising monitoring a charge level of a battery coupled to the electric motor-generator, running the internal combustion engine to charge the battery when the battery reaches a first charge level, and stopping the internal combustion engine when the battery reaches a second charge level. 
     
     
         23 . The method of  claim 16 , further comprising monitoring a speed of the marine vessel, running the internal combustion engine when the marine vessel is moving faster than a first speed, and stopping the internal combustion engine when the marine vessel is moving slower than the first speed. 
     
     
         24 . The method of  claim 16 , further comprising adjusting the torque load of the electric motor-generator with the control circuitry by adjusting a value of a charging current of the electric motor-generator. 
     
     
         25 . A marine propulsion assembly comprising:
 a frame comprising one or more supports configured to attach the frame to a marine vessel;   a propeller shaft hub rotatably coupled to the frame, the propeller shaft hub comprising an interior wall defining an opening adapted to receive an output shaft operatively coupled to a propeller, the propeller shaft hub further comprising a fastening mechanism to attach the propeller shaft hub to the output shaft in a fixed rotational relationship;   a coupling flange attached to the propeller shaft hub, the coupling flange configured to couple to an internal combustion engine;   a transmission rotatably coupled to the propeller shaft hub; and   an electric motor-generator rotatably coupled to the transmission.   
     
     
         26 . The marine propulsion assembly of  claim 25 , wherein the transmission comprises two or more pulleys and a belt that rotatably couple the electric motor-generator to the propeller shaft hub. 
     
     
         27 . The marine propulsion assembly of  claim 25 , wherein the transmission ratio is selected to substantially match the electric motor-generator output speed to a desired speed for the output shaft operatively coupled to the propeller. 
     
     
         28 . The marine propulsion assembly of  claim 25 , wherein a fore-aft distance required by the coupling flange and the propeller shaft hub is less than about four inches. 
     
     
         29 . The marine propulsion assembly of  claim 25 , wherein the coupling flange is adapted to replace an existing propeller shaft coupling flange. 
     
     
         30 . A propulsion system for a marine vessel, comprising:
 the marine propulsion assembly of  claim 26 ;   an internal combustion engine comprising a drive coupling flange coupled to the coupling flange of the marine propulsion assembly in a fixed rotational relationship, the coupling flange of the marine propulsion assembly having a fore-aft length parallel to an axis of the output shaft;   an output shaft having a first end received within and fixedly attached to the propeller shaft hub, the propeller shaft hub having a fore-aft length parallel to the axis of the output shaft; and   a propeller operatively coupled to the output shaft,   wherein the first end of the output shaft is separated from the coupling flange of the internal combustion engine by a distance less than the fore-aft length of the propeller shaft hub.   
     
     
         31 . The propulsion system of  claim 30 , wherein the coupling flange of the marine propulsion assembly comprises a coaxial bore, and wherein the first end of the output shaft is separated from the coupling flange of the internal combustion engine by a distance less than the fore-aft length of the coupling flange of the marine propulsion assembly.