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.

Claims

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.

Description

[0120] Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

[0121] FIGS. 1A-1C show different views of an example of a rim driven thruster according to the invention;

[0122] FIG. 2 shows a cross section along line IIB-IIB in FIG. 1C;

[0123] FIGS. 3A and 3B show an example of a bearing ring for a rim driven thruster according to the invention;

[0124] FIG. 4 shows an example of rotor and axial bearing of a rim driven thruster according to the invention;

[0125] FIG. 5 shows a schematic example of a control for a rim driven thruster according to the invention; and

[0126] FIG. 6 shows a schematic example of the method according to the invention.

[0127] In an example of a rim driven thruster according to the invention (see FIGS. 1A-1C), rim driven thruster 2 comprises housing 4, connector 6 and rotor 8. Connector 6 in this example is a connector to connect rim driven thruster 2 to a ship, boat or floating object to be propelled. Connector 6 may for example contain the electrical connection to an external power source and/or a connection with a control unit (not shown). It is noted that a control unit can also be provided in housing 4.

[0128] Rotor 8 in this example is provided with rotor blades 10, which extend radially inwards from rotor rim 12. It is noted that rotor blades 10 do not touch each other, thus leaving a throughflow opening 14 between rotor blades 10. As a result, rim driven thruster 2 is less susceptible to for instance pollution. It is noted that, in use of rim driven thruster 2, rotor 8 is rotatable around central axis A to generate forward or backward thrust P.

[0129] Rim driven thruster 2 (see FIG. 2) further comprises stator 16, which surrounds rotor 8 and in which rotor 8 is rotatable. Both stator 16 and rotor 8 in this example comprise parts of electromagnetic actuator system 18.

[0130] Rim driven thruster 2 (see FIGS. 2, 3) further comprises axial bearings 26, 28, which are positioned on opposite sides of rotor 8. Each axial bearing 26, 28 comprises respective bearing surface 30, 32 and an associated number of tilting bearing pads 34, 36. In this example (see FIG. 3), bearing pads 34, 36 are positioned on a respective axial bearing support 38, 40.

[0131] In another example, rim driven thruster 102 (see FIGS. 4, 5), of which the features can be combined with the features of rim driven thruster 2 (shown in FIGS. 1-3), comprises rotor 108 comprising rotor blades 110 which extend radially inwards from rotor rim 112 towards central axis A. Near central axis A, opening 124 is present, which prevents pollution.

[0132] Rim driven thruster 102 (see FIG. 4) further comprises axial bearings 126, 128, which are positioned on opposite sides of rotor 108. Each axial bearing 126, 128 comprises respective bearing surface 130, 132 that is positioned on rotor 108 and an associated number of tilting bearing pads 134, 136, which are in this example positioned on a respective axial bearing support 138, 140.

[0133] It is clearly visible (see FIG. 4) that rotor 108 is surrounded by stator 116 and is rotatable therein to generate thrust P in a forward or rearward direction.

[0134] Rim driven thruster 2, 102 may further comprise control unit 150 that is connected to electromagnetic actuator system 18, 118 to control operation of electromagnetic actuator system 18, 118 (see FIG. 5). In addition, rim driven thruster 2, 102 may additionally comprise one or more sensors 152, 154, 156 that are configured for generating measuring data. In this example, sensor 152 for example is a position sensor to measure the relative position of rotor 8, 108 with respect to stator 16, 116. Sensor 154 in this example is current sensor that 154 is configured to measure a current, which allows control unit 150 to calculate a relative position of rotor 8, 108 with respect to stator 16, 116. Sensor 156 represents any other sensor suitable for generating data with which control unit 150 can determine the relative position between rotor 8, 108 and stator 16, 116.

[0135] Based on the measurement data from the one or more sensors 152, 154, 156, control unit 150 is able to control electromagnetic actuator system 18, 118 to correct or maintain a proper electromagnetic bearing and therewith maintain the relative position of the rotor with respect to the stator. It is noted that in this example the electromagnetic radial bearing is the only or sole radial bearing of the rim-driven thruster.

[0136] Optionally, rim driven thruster 2, 102 may comprise signal filtering unit 158 that is configured to filter measurement data from current sensor 154. In this example, signal filtering unit 158 is configured to filter the measurement data in bearing measurement data and rotation measurement data, which are provided to control unit 150 separately. It can also be envisioned that control unit 150 is configured to perform such a filtering step. By separating especially the bearing measurement data from the other measurement data by applying a filtering step in the signal filtering unit 158 a more accurate control by control unit 150 is possible.

[0137] In use of rim driven thruster 2, 102, an electromagnetic bearing is provided by electromagnetic actuation system 18, 118. In addition, the application of a magnetic field by electromagnetic actuation system 18, 118 may also allow a torque to be imparted to rotor 8, 108 to rotate rotor 8, 108.

[0138] In an example of the method according to the invention (see FIG. 6), method 1000 comprises providing 1002 a ship with one or more rim driven thrusters according to the invention, operating 1004 the one or more rim driven thrusters, and propelling 1006 the ship. The step of operating 1004 the one or more rim driven thrusters may comprises several (sub) steps. A first step may be the step of actuating 1008 an electromagnetic actuator system to provide an electromagnetic bearing and, selectively provide torque to the rotor. Another optional step may be the step of controlling 1010, by a control unit, the electromagnetic actuator system to maintain the electromagnetic bearing, and optionally to control a rotation speed of the rotor.

[0139] The method may, alternatively, also comprise other method steps. This may for example include the step of actuating 1008 an electromagnetic actuator system to provide an electromagnetic bearing and, selectively provide torque to the rotor. Additionally, it may include the step of measuring 1012, by at least one sensor, a relative position of the rotor with respect to the stator and/or a current applied in the electromagnetic actuator system. A following step may be the step of controlling 1014, by the control unit and based on measurement data from the measuring step, the electromagnetic actuator system to maintain and/or correct the electromagnetic bearing to maintain the relative position of the rotor with respect to the stator, and the optional step of filtering 1016 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 imparted to the rotor.

[0140] The present invention is by no means limited to the above described preferred embodiments and/or experiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.