Method for starting a combustion engine in a marine hybrid drive unit

Abstract

A method is disclosed for starting a combustion engine in a marine hybrid drive unit where the marine hybrid drive unit includes the combustion engine and an electric drive motor. The combustion engine has an electric starter unit, and the electric drive motor is permanently connected to the driven shaft. A driven shaft of the marine hybrid drive unit can be driven in a combustion engine mode solely by the combustion engine, in an electric propulsion mode solely by the electric drive motor, and in a combined mode by the combustion engine and the electric drive motor. The method includes starting the electric motor and starting the combustion engine by the electric starter unit. Also disclosed is a marine hybrid drive unit comprising a control unit configured to execute the method.

1 . A method for starting a combustion engine ( 1 ) in a marine hybrid drive unit ( 100 ,  200 ), comprising:
 providing a marine hybrid drive unit ( 100 ,  200 ) comprising the combustion engine ( 1 ) and an electric drive motor ( 2 ) permanently connected to a driven shaft ( 4 ) of the marine hybrid drive unit, wherein the combustion engine ( 1 ) comprises an electric starter unit ( 8 ), wherein the driven shaft ( 4 ) of the marine hybrid drive unit ( 100 ,  200 ) is configured to be driven in a combustion engine mode solely by the combustion engine ( 1 ), configured to be driven in an electric propulsion mode solely by the electric drive motor ( 2 ), and configured to be driven in a combined mode by the combustion engine ( 1 ) and the electric drive motor ( 2 );   starting the electric motor ( 2 ); and   starting the combustion engine ( 1 ) by the electric starter unit ( 8 ).   
     
     
         2 . The method according to  claim 1 , comprising:
 connecting the combustion engine ( 1 ) to the driven shaft ( 4 ) by means of a pressure actuated input clutch ( 5 ) before starting the combustion engine ( 1 );   providing oil pressure for actuating a pressure actuated input clutch ( 5 ) by an oil pump ( 6 ) driven by the driven shaft ( 4 ); and   closing the pressure actuated input clutch after starting the electric drive motor ( 2 ).   
     
     
         3 . The method according to  claim 1 , comprising:
 determining that the combustion engine ( 1 ) has reached a preset engine speed; and   switching the marine hybrid drive unit ( 100 ,  200 ) to the combustion engine mode, when the combustion engine ( 1 ) has reached a preset engine speed.   
     
     
         4 . The method according to  claim 3 , comprising:
 setting the preset engine speed to a value in a range between 600 rpm and 800 rpm.   
     
     
         5 . A marine hybrid drive unit ( 100 ,  200 ) comprising a control unit ( 101 ,  201 ), which is configured to execute the method according to  claim 1 . 
     
     
         6 . The marine hybrid drive unit ( 100 ,  200 ) according to  claim 5 , wherein the electric drive motor ( 2 ) is part of a hybrid module ( 10 ,  20 ) comprising at least one gear step ( 7 ) between the electric drive motor ( 2 ) and the driven shaft ( 4 ). 
     
     
         7 . The marine hybrid drive unit ( 100 ,  200 ) according to  claim 6 , wherein the ratio of the at least one gear step ( 7 ) is set to a value in the range between 2 and 3. 
     
     
         8 . The marine hybrid drive unit ( 100 ,  200 ) according to  claim 5 , wherein the hybrid module ( 10 ) comprises the pressure actuated input clutch ( 5 ). 
     
     
         9 . The marine hybrid drive unit ( 100 ,  200 ) according to  claim 5 , wherein the hybrid module ( 10 ) comprises an input clutch ( 23 ) in form of a freewheel unit, wherein an input element ( 21 ) of the freewheel unit is connected to a crankshaft ( 9 ) of the combustion engine ( 1 ) and wherein an output element ( 22 ) of the freewheel unit is connected to the electric drive motor ( 2 ) and to the driven shaft ( 4 ). 
     
     
         10 . The marine hybrid drive unit according to  claim 6 , wherein the driven shaft ( 4 ) is an input shaft of a gearbox ( 14 ) and wherein the oil pump ( 6 ) is an integral part of the gearbox ( 14 ).