Rim Driven Thruster and Method for Propelling a Ship

Abstract

The invention relates to a rim driven thruster, comprising: a stator body; an annular rotor body that is positioned in the stator and that comprises radially inwardly projecting blades; at least one axial bearing adjacent to the rotor, wherein the at least one axial bearing is configured to transfer and/or contain axial tilt and/or axial forces acting on the rotor body; an electromagnetic actuator system that is configured to selectively impart a driving force to the rotor; and an electromagnetic radial bearing between the stator and the rotor. The invention further relates to a ship with one or more of such rim driven thrusters and a method for propelling a ship.

1 . A rim driven thruster, comprising:
 a stator body;   an annular rotor body that is positioned in the stator and that comprises radially inwardly projecting blades;   at least one axial bearing adjacent to the rotor, wherein the at least one axial bearing is configured to transfer and/or contain axial tilt and/or axial forces acting on the rotor body;   an electromagnetic actuator system that is configured to selectively impart a driving force to the rotor;   an electromagnetic radial bearing between the stator and the rotor;   a control unit that is configured for controlling the electromagnetic actuator system to selectively drive the rotor, and wherein the control unit is configured for controlling the electromagnetic actuator system to generate and/or maintain the electromagnetic bearing;   at least one sensor that is configured to direct or indirectly measure a position of the rotor with respect to the stator, and wherein sensor measurement data comprises bearing data and rotation drive data; and   a signal filter that is configured to separate the bearing data and the rotation drive data from each other.   
     
     
         2 . The rim driven thruster according to  claim 1 , wherein the electromagnetic actuator system is configured to generate and/or maintain the electromagnetic bearing. 
     
     
         3 . The rim driven thruster according to  claim 1 , wherein the electromagnetic actuator system comprises a number of magnetizable coils that is distributed along a circumference of the stator, and wherein the control unit is configured to control a current in the number of coils. 
     
     
         4 . The rim driven thruster according to  claim 1 , wherein the at least one sensor is configured to direct or indirectly measure a radial position of the rotor with respect to the stator. 
     
     
         5 . The rim driven thruster according to  claim 4 , wherein the at least one sensor is configured to measure one or more of:
 an electromagnetic field strength and/or deviations therein; and/or   a current through (at least a portion of) the electromagnetic actuator system; and/or   a direct relative position between the rotor and the stator.   
     
     
         6 . The rim driven thruster according to  claim 4 , wherein the control unit is configured to control the electromagnetic actuator system based on sensor measurement data to provide and/or maintain the electromagnetic bearing between the rotor and the stator. 
     
     
         7 . The rim driven thruster according to  claim 1 , wherein the at least one axial bearing comprises a hydrodynamic bearing. 
     
     
         8 . The rim driven thruster according  claim 7 , wherein the at least one hydrodynamic bearing comprises:
 a number tiltable bearing pads that are operatively connected to the stator; and   at least one bearing surface positioned on a side of the rotor; wherein the bearing pads and the at least one bearing surface are facing each other to form the axial bearing.   
     
     
         9 . The rim driven thruster according to  claim 8 , wherein the bearing pads comprise a base layer and a coating, and wherein the bearing surface comprises a material that has a hardness that is lower than a hardness of the coating. 
     
     
         10 . The rim driven thruster according to  claim 8 , wherein the bearing surface comprises a base layer and a coating, and wherein the bearing pads comprise a material that has a hardness that is lower than a hardness of the coating. 
     
     
         11 . The rim driven thruster according to  claim 1 , wherein the axial bearing has a thickness, measured in an axial direction, in the range of 5-50 mm, or wherein the axial bearing has a thickness, measured in an axial direction, in the range of 2-20% of a bearing diameter. 
     
     
         12 . The rim driven thruster according to  claim 9 , wherein a width of the bearing pads, measured in a radial direction, is in the range of 2%-30% of a rotor diameter. 
     
     
         13 . The rim driven thruster according to  claim 9 , wherein the number of bearing pads, when viewed along the circumference of the bearing, is in the range of 3-42. 
     
     
         14 . The rim driven thruster according to  claim 9 , wherein the bearing pads, when viewed along the circumferential direction of the stator, cover a portion of a surface of the stator in the range of 15%-90%. 
     
     
         15 . The rim driven thruster according to  claim 1 , comprising a thruster housing in which the stator and the rotor are positioned, wherein the housing preferably is an elongated housing that extends substantially around a central axis of the rotor over a predetermined length, wherein the elongated housing is shaped to, during use, create a pressure difference over the housing. 
     
     
         16 . A ship comprising one or more rim driven thrusters according to  claim 1 . 
     
     
         17 . A method for propelling a ship, the method comprising:
 providing a ship with one or more rim driven thrusters according to claim;   operating the one or more rim driven thrusters; and   propelling the ship.   
     
     
         18 . The method according to  claim 17 , wherein the step of operating the one or more rim driven thrusters comprises:
 actuating an electromagnetic actuator system to provide an electromagnetic bearing and, to selectively provide rotation to the rotor;   optionally, controlling, by a control unit, the electromagnetic actuator system to maintain the electromagnetic bearing, and   optionally controlling, by a control unit, the electromagnetic actuator system to control a rotation speed of the rotor.   
     
     
         19 . The method according to  claim 18 , further comprising:
 directly or indirectly measuring a relative position of the rotor with respect to the stator;   controlling, based on measurement data obtained in the measuring step, the electromagnetic actuator system to maintain and/or correct the electromagnetic bearing; and   optionally filtering the measurement data from the measuring step to obtain bearing data related to the electromagnetic bearing and/or rotation drive data relating to a rotation of and/or torque exerted on the rotor.