Thruster for propelling a watercraft

Abstract

A thruster for propelling a watercraft comprises at least one propeller on a rotatable propeller shaft and a motor for driving the propeller shaft through a drive arrangement, particularly a drive arrangement comprising a rotatable drive shaft and a coupling arrangement arranged between the drive shaft and an output shaft of the motor for coupling the drive shaft to the output shaft of the motor. The motor is a permanent magnet motor, the stator body of the motor being provided with a recess surrounding at least a part of the output shaft of the motor, and the coupling arrangement being at least partially located inside the recess so that a configuration having minimal constructional height is obtained.

Claims

1. A thruster for propelling a watercraft, comprising: at least one propeller arranged on a propeller shaft to be rotated during operation of the thruster; a motor for driving the propeller shaft, comprising a rotatable output shaft; a drive arrangement coupling the propeller shaft to the output shaft of the motor, the drive arrangement comprising a rotatable drive shaft and a coupling arrangement arranged between the drive shaft and the output shaft of the motor for coupling the drive shaft to the output shaft of the motor, the drive shaft extending in substantially the same direction as the output shaft of the motor, and the propeller shaft being perpendicular to both the drive shaft and the output shaft of the motor; and a housing arrangement comprising a gearbox portion for accommodating the propeller shaft and other components including gearing components, an end of the drive shaft extending into the gearbox portion, and a tube-shaped housing portion accommodating and surrounding a part of the drive shaft, connecting to the gearbox portion at one side thereof; wherein the motor is a permanent magnet motor and comprises a stationary stator body and a rotatable rotor body, the output shaft of the motor extending from the rotor body; and wherein the stator body is provided with a recess at a side of the stator body where the drive arrangement is located, the recess surrounding at least a part of the output shaft of the motor, and the coupling arrangement being at least partially located inside the recess.

2. A thruster according to claim 1, further comprising an azimuth arrangement for setting an angular position of the propeller shaft with respect to stationary components of the thruster including the stator body of the motor, the azimuth arrangement comprising a slewing bearing including an outer ring supported on and fixedly connected to a steering flange, and at least one motor-driven pinion engaging with the ring for rotating the ring to an angular position as desired, wherein the tube-shaped housing portion is fixedly connected to the steering flange at the other side thereof.

3. A thruster according to claim 2, wherein: the steering flange has a central opening, the coupling arrangement being partially received in the steering flange at the position of the opening, and the drive shaft extending partially through the steering flange, and the steering flange comprises a sleeve-shaped portion besides a flange-shaped portion, the sleeve-shaped portion being centrally arranged in the steering flange and extending in the direction of the tube-shaped housing portion, the tube-shaped housing portion and the gearbox portion being suspended from the sleeve-shaped portion of the steering flange.

4. A thruster according to claim 3, wherein the outer ring of the slewing bearing and an inner ring of the slewing bearing about which the outer ring is rotatable are arranged at a level for surrounding a part of the stator body of the motor, the flange-shaped portion of the steering flange being at a position for facing the motor at close range.

5. A thruster according to claim 3, wherein the flange-shaped portion of the steering flange is provided with a pattern of recesses and ribs at a surface thereof facing the motor.

6. A thruster according to claim 5, wherein ribs extending in the same direction as the propeller shaft are broader than the other ribs of the pattern.

7. A watercraft, comprising at least one thruster according to claim 1.

8. A thruster according to claim 4, wherein the flange-shaped portion of the steering flange is provided with a pattern of recesses and ribs at a surface thereof facing the motor.

9. A thruster according to claim 8, wherein ribs extending in the same direction as the propeller shaft are broader than the other ribs of the pattern.

10. A watercraft, comprising at least one thruster according to claim 2.

11. A watercraft, comprising at least one thruster according to claim 3.

12. A watercraft, comprising at least one thruster according to claim 4.

13. A watercraft, comprising at least one thruster according to claim 5.

14. A watercraft, comprising at least one thruster according to claim 6.

15. A watercraft, comprising at least one thruster according to claim 8.

16. A watercraft, comprising at least one thruster according to claim 9.

Description

(1) The invention will now be explained in greater detail with reference to the figures, in which equal or similar components are indicated by the same reference signs, and in which:

(2) FIG. 1 diagrammatically shows a perspective view a thruster according to a preferred embodiment of the invention;

(3) FIG. 2 diagrammatically shows an exploded view of the thruster shown in FIG. 1;

(4) FIG. 3 diagrammatically shows a detail of FIG. 2; and

(5) FIG. 4 diagrammatically shows a sectional view of the thruster shown in FIG. 1.

(6) The orientation of the thruster and the various components thereof as shown in the figures is related to the normal, operational orientation of the thruster mentioned in the foregoing. It is emphasized once again that indications such as vertical, horizontal, lower and higher or upper as used in the present description with reference to the figures are to be understood in the context of that normal, operational orientation, and not such as to be limiting to the scope of the invention in any way.

(7) FIGS. 1-4 relate to a thruster 1 according to a preferred embodiment of the invention. In conformity with the general description of a thruster as provided in the foregoing, it is noted that the thruster 1 is designed to be used for propelling a watercraft and to be fixedly attached to a watercraft at a suitable position on the watercraft's hull, with an upper, dry portion 2 positioned inside the watercraft's hull and a lower, wet portion 3 extending downwardly from the watercraft's hull.

(8) At a lowest level, the thruster 1 comprises at least one rotatable propeller for realizing (part of) the propulsion that is needed for moving a watercraft. In the shown example, two contra-rotating propellers 11, 12 are used, which does not alter the fact that the invention is applicable to thrusters comprising only one propeller as well. As can be seen in FIG. 4, the propellers 11, 12 are arranged on respective propeller shafts 13, 14, at two sides of a gearbox portion 15 accommodating a number of components besides the propeller shafts 13, 14, such as gearing components 16 and bearings 17. The propeller shafts 13, 14 extend in substantially the same direction and at the same vertical level, one propeller shaft 13 extending from a central position inside the gearbox portion 15 to a first side of the gearbox portion 15, and the other propeller shaft 14 extending from the central position inside the gearbox portion 15 to a second, opposite side of the gearbox portion 15.

(9) For the purpose of rotating the propeller shafts 13, 14 during operation, the thruster 1 is equipped with a motor 20. The motor 20 is a permanent magnet motor of which only the stator body 21 and the output shaft 22 are shown in FIG. 4. For the sake of clarity, other components which are known to be part of a permanent magnet motor, such as a rotor body and windings arranged thereon, are not shown. The thruster 1 furthermore comprises a drive arrangement coupling the propeller shafts 13, 14 to the output shaft 22 of the motor 20, the drive arrangement comprising a rotatable drive shaft 31 and a coupling arrangement 32 arranged between the drive shaft 31 and the output shaft 22 of the motor 20 for coupling the drive shaft 31 to the output shaft 22 of the motor 20 at a highest end thereof. The drive shaft 31 extends in substantially the same direction as the output shaft 22 of the motor 20, namely in a substantially vertical direction, whereas the respective propeller shafts 13, 14 are perpendicular to both the drive shaft 31 and the output shaft 22 of the motor 20, i.e. extend in a substantially horizontal direction.

(10) As explained in the foregoing, the gearbox portion 15 serves for accommodating the propeller shafts 13, 14 and other components 16, 17. A lower end 33 of the drive shaft 31 extends into the gearbox portion 15, engaging with respective gears for imposing rotary movement on the respective propeller shafts 13, 14 during operation of the thruster 1. A major part of the drive shaft 31 is accommodated in and surrounded by a steering tube 34 that connects to the gearbox portion 15 at a lower side thereof, and that preferably constitutes one integral housing arrangement in combination with the gearbox portion 15. Suitable bearings 35, 36 are arranged between the interior surface of the steering tube 34 and the drive shaft 31.

(11) Advantageously, in order for the thruster 1 to be useful for determining a direction of movement of a watercraft once installed on the watercraft, the thruster 1 is equipped with an azimuth arrangement. Within the framework of the invention, it is not essential that the thruster 1 has this added functionality of performing a steering action on a watercraft. When the thruster 1 comprises an azimuth arrangement, as is the case in the shown example, the azimuth arrangement is used for setting an angular position of the respective propeller shafts 13, 14 in the thruster 1, i.e. with respect to stationary components of the thruster 1. Thus, when an azimuth arrangement is present in the thruster 1, it is possible to vary the direction in which the propeller shafts 13, 14 extend in the horizontal plane with respect to the stationary components of the thruster 1 and consequently, when the thruster 1 is mounted on a watercraft, to the watercraft. In particular, the azimuth arrangement is configured and arranged to vary the horizontal angular position of the propeller shaft 13, 14 by varying the horizontal angular position of the assembly of the gearbox portion 15 and the steering tube 34. To this end, the azimuth arrangement comprises a slewing bearing including an outer ring 41 and an inner ring 42 about which the outer ring 41 is rotatable, and a steering flange 50, the outer ring 41 being supported on and fixedly connected to the steering flange 50, and the inner ring 42 being fixedly connected to a thruster foundation 61. FIG. 2 clearly illustrates the fact that in the shown example, the thruster foundation 61 is combined with another foundation component, namely a so-called bottom well 62 serving as a counter foundation component to which the thruster foundation 61 is fixedly connected.

(12) The thruster 1 according to the shown embodiment comprises two electric motors 43, 44 for driving respective pinions 45, 46 that are in engagement with the outer ring 41 of the slewing bearing. The motors 43, 44 are supported on a carrier frame 63 that is fixedly connected to the combination of the thruster foundation 61 and the bottom well 62. By controlling the operation of the motors 43, 44 in a synchronized way, the angular position of the propeller shafts 13, 14 can be continuously varied as desired and dictated by manual or automatic steering input. For the sake of completeness, it is noted that the number of pinions 45, 46 and associated motors for controlling an angular position of the outer ring 41 of the slewing bearing is at least one, that the number may be two as illustrated, and that the number may also be more than two, whatever is appropriate in a particular case.

(13) In the shown example, the steering flange 50 has a central opening 51 and comprises a flange-shaped portion 52 and a sleeve-shaped portion 53 extending downwardly with respect to the flange-shaped portion 52. At an upper side of the steering flange 50, the coupling arrangement 32 is partially received in the steering flange 50, whereas the sleeve-shaped portion 53 is at a position for surrounding a top end of the drive shaft 31. The assembly of the steering tube 34 and the gearbox portion 15 is fixedly connected to the sleeve-shaped portion 53 of the steering flange 50 through a coupling flange 37.

(14) Various components of the thruster 1, such as the gearbox portion 15, the steering tube 34, the sleeve-shaped portion 53 of the steering flange 50 and the thruster foundation 61 have a function in covering rotating components and preventing water from reaching the components positioned inside. The thruster 1 is provided with two sealing arrangements 71, 72, one sealing arrangement 71 being arranged at the interface of the dry portion 2 and the wet portion 3 of the thruster 1, and the other sealing arrangement 72 being arranged between the steering flange 50 and the coupling arrangement 32.

(15) The thruster 1 is operated by having the motor 20 in an active condition, i.e. a condition in which the output shaft 22 of the motor 20 rotates. The rotary movement of the output shaft 22 of the motor 20 is transmitted all the way down to the propeller shafts 13, 14 and the propellers 11, 12 through the coupling arrangement 32, the drive shaft 31 and the gears as present in the gearbox portion 15 and engaged by the lower end 33 of the drive shaft 31. Adjustments of the angular position of the propeller shafts 13, 14 as desired are obtained by rotating the pinions 45, 46 engaging the outer ring 41 of the slewing bearing, by means of the motors 43, 44 that are provided for that purpose. When the position of the ring 41 is adjusted over a certain angle, the position of the steering flange 50, the coupling flange 37, the steering tube 34 and the gearbox portion 15 including the propeller shafts 13, 14 is adjusted as well, in the same way.

(16) A notable feature of the thruster 1 according to the invention resides in the fact that the thruster 1 has a compact design. Particularly, the height of the dry portion 2 of the thruster 1 is as low as possible, due to the fact that the motor 20 is a permanent magnet motor and that the design of the motor 20 is chosen so that the motor 20 can be arranged as low as possible on the underlying components of the thruster 1. The fact is that the stator body 21 of the motor 20 is provided with a recess 23 at a bottom side thereof. The shape of the recess 23 is adapted to the shape of the coupling arrangement 32, so that the coupling arrangement 32 can be partially located inside the recess 23. Furthermore, in this low position of the motor 20 with respect to the coupling arrangement 32, the flange-shaped portion 52 of the steering flange 50 extends right underneath the motor, and the slewing bearing including the outer ring 41 and the inner ring 42 about which the outer ring 41 is rotatable is located at a level for surrounding a part of the stator body 21 of the motor 20. With respect to a conventional design of a thruster, the motor 20, a top portion of the drive arrangement and components of the azimuth arrangement are positioned more closely together, without compromising the main functionalities of the thruster.

(17) Within the framework of the invention, it is possible for the steering flange 50 to be a massive component, but it is preferred if the flange-shaped portion 52 of the steering flange 50 is provided with a pattern 54 of recesses 55 and ribs 56 at the upper surface thereof, i.e. the surface facing the motor 20, as is the case in the shown example, so that the steering flange 50 can have limited weight and still have sufficient constructional strength. In such a pattern 54, it is advantageous if ribs 56a extending in the same direction as the propeller shafts 13, 14 are broader than the other ribs 56 of the pattern 54, as is the case in the shown example.

(18) It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive.

(19) The various components of the thruster 1 according to the invention can be made of any suitable materials, including metal materials and plastic materials.

(20) The compact design of the dry portion 2 of the thruster 1 according to the invention can be combined with any suitable design of the wet portion 3 of the thruster 1. For example, the wet portion 3 may have a larger length when compared to the dry portion 2 than illustrated in the figures, wherein it is possible that a generally cone-shaped arrangement known per se is applied, which may serve for providing bearing support to the slewing bearing in case the thruster 1 is an azimuth thruster.