Marine propulsion system

Abstract

The present disclosure relates to a marine propulsion system for a marine vessel, having an engine, a propeller unit having one or more propellers, a transmission arranged between the engine and the propeller unit, a clutch arrangement arranged in connection with the transmission. The clutch arrangement transfers power between the engine and the propeller unit. An input unit is configured to receive an input signal indicative of a propeller speed and to issue a propeller speed reference based on the input signal. The propulsion system comprises a control unit being operatively connected with the propeller unit, the clutch arrangement and the input unit, the control unit is configured to control the propulsion system based on propeller speed references during varying operations and/or speeds of the marine propulsion system.

What is claimed is: 
     
         1 . A marine propulsion system for a marine vessel, comprising
 an engine,   a propeller unit having one or more propellers,   a transmission arranged between the engine and the propeller unit,   a clutch arrangement arranged in connection with the transmission, the clutch arrangement is configured to transfer power between the engine and the propeller unit, and   an input unit, the input unit is configured to receive an input signal indicative of a propeller speed and to issue a propeller speed reference based on the input signal,   wherein the propulsion system further comprises a control unit being operatively connected with the propeller unit, the clutch arrangement and the input unit, the control unit is configured to control the propulsion system based on propeller speed references during varying operations and/or speeds of the marine propulsion system.   
     
     
         2 . The marine propulsion system of  claim 1 , wherein the control unit further comprises a propeller speed controller, the propeller speed controller is configured to control the propeller speed on basis of the propeller speed references. 
     
     
         3 . The marine propulsion system of  claim 1 , wherein the clutch arrangement comprises a clutch plate and a clutch piston, the clutch piston being activated by at least one hydraulic area so as to provide an actuation pressure on the clutch plate. 
     
     
         4 . The marine propulsion system of  claim 3 , wherein the clutch arrangement has a predetermined actuation pressure, the predetermined actuation pressure is a pressure reference. 
     
     
         5 . The marine propulsion system of  claim 1 , wherein the clutch arrangement comprises one or more pressure sensor(s), the pressure sensor being configured to detect and/or measure an actuation pressure of the clutch arrangement. 
     
     
         6 . The marine propulsion system of  claim 5 , wherein the control unit comprises an actuation pressure controller, the actuation pressure controller is configured to control the actuation pressure on basis of the pressure reference and/or the measured actuation pressure. 
     
     
         7 . The marine propulsion system of  claim 6 , wherein one or more pressure sensors are operatively connected with the actuation pressure controller. 
     
     
         8 . The marine propulsion system of  claim 7 , wherein the pressure sensor(s) is/are configured to measure forward and/or reverse actuation pressure, the measured actuation pressure is used as feedback to the actuation pressure controller. 
     
     
         9 . The marine propulsion system of  claim 6 , wherein the actuation pressure controller is configured to control the actuation pressure of the clutch arrangement by a closed-loop control. 
     
     
         10 . The marine propulsion system of  claim 3 , wherein the clutch piston is configured to be actuated by a first hydraulic area and/or a second hydraulic area. 
     
     
         11 . The marine propulsion system of  claim 10 , wherein the first hydraulic area is pressurized by an electrically controlled proportional pressure valve and the second hydraulic area is pressurized by an electrically controlled on/off valve. 
     
     
         12 . The marine propulsion system of  claim 11 , wherein an electrically controlled valve, the electrically controlled proportional pressure valve and/or the electrically controlled on/off valve is/are controlled by a predetermined current, the predetermined current is a current reference. 
     
     
         13 . The marine propulsion system of  claim 12 , wherein the control unit comprises a current controller, the current controller is configured to closed-loop current control the electrically controlled valve, the electrically controlled proportional pressure valve and/or the electrically controlled on/off valve on basis of the current reference. 
     
     
         14 . The marine propulsion system of  claim 1 , further comprising an engine controller, the engine controller is configured to control an engine speed on basis of the propeller speed reference. 
     
     
         15 . The marine propulsion system of  claim 14 , wherein the engine controller is configured to increase engine speed near full clutch engagement so that the clutch engagement is kept below where slip-stick behavior of the clutch disc may occur. 
     
     
         16 . The marine propulsion system of  claim 14 , wherein the control unit and the engine controller are operatively connected. 
     
     
         17 . A marine vessel comprising a marine propulsion system of  claim 1 . 
     
     
         18 . A method of controlling a marine propulsion system of  claim 1 , comprising providing a control unit being operatively connected with the propeller unit, the transmission and the clutch arrangement,
 receiving an input signal from the input unit,   issuing a propeller speed reference based on the input signal,   controlling the propulsion system on basis on the propeller speed references during varying operations and/or speeds of the marine propulsion system.   
     
     
         19 . The method of  claim 18 , further comprising setting and/or calculating a predetermined actuation pressure, the predetermined actuation pressure is a pressure reference. 
     
     
         20 . The method of  claim 19 , further comprising measuring an actuation pressure of the clutch arrangement.