Marine hybrid drive unit and method to drive such a marine hybrid drive unit

Abstract

A marine hybrid drive unit ( 100 ) has an electric motor ( 2 ) and a transmission ( 3 ). The transmission ( 3 ) has an input shaft ( 4 ), an output shaft ( 5 ), and a pressure actuated transmission clutch ( 6 ) configured to selectively connect the input shaft ( 4 ) to the output shaft ( 5 ). The input shaft ( 4 ) can selectively be driven solely by a combustion engine ( 1 ), solely by the electric motor ( 2 ), or by both the combustion engine ( 1 ) and the electric motor ( 2 ) simultaneously. The transmission ( 3 ) further includes a main oil pump ( 7 ), driven by the input shaft ( 4 ) to provide oil pressure for actuating the pressure actuated transmission clutch ( 6 ). An auxiliary oil pump ( 8 ) provides oil pressure to the pressure actuated transmission clutch ( 6 ) during operation in a low-speed range. Also disclosed is a method for driving such a marine hybrid drive unit.

1 . A marine hybrid drive unit ( 100 ), comprising:
 an electric motor ( 2 );   a transmission ( 3 ),
 comprising an input shaft ( 4 ), an output shaft ( 5 ), and a pressure actuated transmission clutch ( 6 ) configured to selectively connect the input shaft ( 4 ) to the output shaft ( 5 ), wherein the input shaft ( 4 ) is configured to selectively be driven solely by a combustion engine ( 1 ), solely by the electric motor ( 2 ), or by the combustion engine ( 1 ) and the electric motor ( 2 ) simultaneously; 
   a main oil pump ( 7 ) driven by the input shaft ( 4 ) and configured to provide oil pressure for actuating the pressure actuated transmission clutch ( 6 ); and   an auxiliary oil pump ( 8 ) configured for providing oil pressure to the pressure actuated transmission clutch ( 6 ) during operation in a low-speed range.   
     
     
         2 . The marine hybrid drive unit ( 100 ) according to  claim 1 , comprising a control unit ( 101 ) configured to actuate the auxiliary oil pump ( 8 ) when a speed control signal is below 5 knots. 
     
     
         3 . The marine hybrid drive unit ( 100 ) according to  claim 1 , comprising a control unit ( 101 ) configured to actuate the auxiliary oil pump ( 8 ) when a rotation speed of the input shaft ( 4 ) is below a preset threshold in a range between 500 and 700 rpm. 
     
     
         4 . The marine hybrid drive unit ( 100 ) according to  claim 3 , wherein control unit ( 101 ) is configured to actuate the auxiliary oil pump ( 8 ) when the input shaft ( 4 ) is driven solely by the electric motor ( 2 ). 
     
     
         5 . The marine hybrid drive unit ( 100 ) according to  claim 1 , comprising:
 a pressure actuated input clutch ( 15 ) configured to connect and disconnect the combustion engine ( 1 ) to the input shaft ( 4 ), wherein the main oil pump ( 7 ) and the auxiliary oil pump ( 8 ) are arranged to provide oil for the actuation of the pressure actuated input clutch ( 15 ).   
     
     
         6 . The marine hybrid drive unit ( 100 ) according to  claim 1 , comprising an oil lubrication system, wherein the main oil pump ( 7 ) and the auxiliary oil pump ( 8 ) are connected to the oil lubrication system to supply oil to the oil lubrication system. 
     
     
         7 . The marine hybrid drive unit ( 100 ) according to  claim 1 , wherein the auxiliary oil pump ( 8 ) is positioned outside of a transmission housing ( 9 ) of the transmission ( 3 ). 
     
     
         8 . A method for driving the marine hybrid drive unit ( 100 ) according to  claim 1 , comprising:
 driving the input shaft ( 4 ) in a low-speed range solely by the electric motor ( 2 ) while providing the pressure for the pressure actuated transmission clutch ( 6 ) by an auxiliary oil pump ( 8 ).   
     
     
         9 . The method according to  claim 8 , wherein the low-speed range is defined to boat speeds between 0 and 5 knots. 
     
     
         10 . The method according to  claim 8 , wherein the low-speed range is defined to rotation speeds of the input shaft ( 4 ) below a preset threshold in a range between 500 and 700 rpm.