TECHNICAL FIELD

The present invention relates to a propeller nozzle attachment arrangement comprising a first and a second attachment member, a propeller propulsion arrangement and a vessel having such a propeller propulsion arrangement. The present invention also relates to a method for attaching a propeller nozzle using the propeller nozzle attachment

arrangement. BACKGROUND OF THE INVENTION

Nozzle propellers are generally used in so-called service vessels, e.g. tow boats (tugs). At low speeds the propulsion thrust can be increased by using nozzle propellers thus it is generally considered that highly loaded propellers on slow moving vessels benefit the most from nozzle propellers. Generally the inflow velocity of the water into the nozzle is increased, reducing pressure. This lowers thrust and torque of the propeller. Due to that the water is slightly circulated at the surface of the nozzle, an inwards aimed force occurs, which has a slight forward aim. The nozzle thereby provides for a small positive thrust which is normally larger than the thrust reduction of the propeller. At about 10 knots this advantage disappears as the nozzle, or shrouding add drag.

Installation and maintenance of propeller nozzles are difficult due to the shear size and weight of the parts. Further, the propellers themselves are expensive and sensitive to outer force as they are generally made from bronze. This puts a lot of strain on the service crew installing and performing maintenance on the nozzle propellers. Maintenance can take a long time, during which time the vessel is usually put in a drydock. This is of course expensive as the vessel cannot be operational thereby earning its pay.

A solution to save time and ease the installation of a nozzle is suggested in the US patent with No. US 6,062,925. The '925 patent discloses a demountable propeller nozzle which enables the propeller nozzle to be demounted before entering icy waters and remounted when reaching ice free waters. The nozzle can be attached to the vessel by means of a flange joint or e.g. a dove tail joint. However, the small clearance between the propeller and nozzle is critical to reduce tip vortex. A low tip vortex in turn increases efficiency of the propeller. Hence there is lot to gain by keeping the distance small and even more to gain by keeping the distance between the propeller tips and the inner surface of the nozzle constant. The '925 patent does not provide for an adequate solution to this problem.

Likewise, the publication of WO 2008/147208 discloses a system for attaching a propeller nozzle to a vessel by means of a system including tensioned struts. The system aims at solving the time consuming process of installing the propeller nozzle but still leaves a lot to wish for.

SUMMARY OF THE INVENTION

The above mentioned problems are at least partly solved or at least reduced by a propeller nozzle attachment arrangement, according to the present invention. The propeller nozzle attachment is adapted for attaching a propeller nozzle to a part of a vessel. The arrangement comprises a first attachment member and a second attachment member. The first and second attachment members each comprises a contact surface arranged to be in working cooperation with each other during assembly. The arrangement further comprises retaining means for retaining the first attachment member with respect to the second attachment member in a fixed position. The first attachment member is further arranged to be in working cooperation with the second attachment member to be movable in at least a first and a second dimension, enabling the position of the first attachment member to be adjusted with respect to the position of the second attachment member before retaining the first attachment member with respect to the second attachment member in the fixed position.

The present invention enables a propeller nozzle to be installed in an effortless manner. The positioning of the first or the second attachment members is further not critical as they can be adjusted with respect to each other during the assembly of a propeller nozzle to a vessel. This makes the assembly of a propeller nozzle to a vessel fast and simple and thereby reduced the amount of time the vessel needs to spend in a drydock. It further simplifies the assembly of a propeller propulsion arrangement as the exact position of the first and/or the second attachment member is not as critical as compared with the solutions of the prior art. In an embodiment of the present invention, the first attachment member is retained to the second attachment member by means of the retaining means in a at least a third dimension, the third dimension being separated from the first and second dimensions. This enables a propeller nozzle to be primarily attached to the vessel, thereafter it enables adjustment of the position of a propeller nozzle with respect to the vessel, e.g. a gear house of the vessel, to put the propeller nozzle in an advantageous position. Such an advantageous position can be in a position where the clearance between the propeller blade tip and the inner surface the propeller nozzle enables a low tip vortex. In an embodiment according to the present invention, the first contact surface is formed by a recess. The first attachment member thus comprises a recess advantageously with a substantially hemispherical form. A part of the second attachment member can be formed with a corresponding form to be in working cooperation with the first attachment member. Hence, the second contact surface can be formed by a protrusion, advantageously with a substantially hemispherical form. The recess of the first attachment member is

advantageously eccentrically positioned with respect to the first attachment member, or its centre axis, and/or the protrusion of the second attachment member is advantageously eccentrically positioned with respect to the second attachment member, or its centre axis. This provides a sophisticated arrangement which enables a good and easy adjustment of the propeller nozzle while at the same time it enables broader tolerances during installation, for example the positioning of e.g. the second attachment member to the vessel, as the final position of the propeller nozzle can be adjusted during assembly. It also enables broader tolerances during manufacturing or when machining components, e.g. propeller nozzles, gear houses, etc. The contact surfaces can optionally be substantially flat, i.e. an extension in only two dimensions, with either a smooth or a structured topography, i.e. surface, and having eccentrically positioned through holes.

According to an embodiment of the present invention, the first attachment member is adapted to be arranged on the propeller nozzle and the second attachment member is adapted to be arranged to the vessel or parts of the vessel, such as on a gear house of the vessel. At certain positions it can be advantageous to use an intermediate member to attach the nozzle attachment arrangement, to the vessel.

In an embodiment according to the present invention, at least one of the first and the second attachment members are arranged with a through hole. The through hole is arranged to be in working cooperation with the retaining means for attaching the first attachment member to the second attachment member and subsequently to fix the position of the first attachment member to the second attachment member, thereby attaching the propeller nozzle to the vessel. The substantially hemispherical form, as mentioned above, can incorporate an opening for a through hole or hole, thereby having side walls around such through hole or hole exhibiting a radius curvature. Hence, although the through hole or hole itself nullifies parts of the hemisphere, the remaining structure can still be considered to exhibit a substantially hemispherical form. The protrusion can exhibit a substantially hemispherical form, as mentioned above, however also other forms are possible such as conical or cylindrical forms.

The through holes are advantageously centrically positioned with respect to the first and second attachment members. As such, the through holes of the first and the second attachment member can be eccentrically positioned with respect to the recess and/or the protrusion.

The first and the second contact surface of the first and the second attachment member can exhibit a smooth surface, enabling a continuous adjustment motion of the first attachment member with respect to the second attachment member. Optionally, the first and the second attachment member each comprises a structured surface, corresponding with each other, e.g. the first attachment member may comprises small grooves while the second attachment member comprises small protrusions or vice verse, enabling a step wise adjustment of the first attachment member with respect to the second attachment member.

The first and the second attachment member are retained by retaining means, e.g. a retaining member such as a screw or a bolt extending through the through holes of the first and second attachment members.

The present invention also relates to a propeller propulsion arrangement comprising at least one propeller nozzle attachment arrangement as described herein, a propeller nozzle and at least one propeller. A propulsion propeller arrangement can comprise everything from one, two or three or more propeller nozzle attachment arrangements. The present invention also relates to a vessel having at least one propeller propulsion arrangement as described herein.

The present invention also relates to a method for attaching a propeller nozzle to a vessel using a propeller nozzle attachment arrangement. In general the method comprises the steps of attaching the propeller nozzle to the vessel in a first position using retaining means. Adjusting the position of the propeller nozzle to a second position and thereafter tightening said retaining means to fix said propeller nozzle at said second position. Generally the present invention relates to a propeller nozzle attachment arrangement adapted for attaching a propeller nozzle to a part of a vessel. The arrangement comprises a first attachment member and a second attachment member arranged to be in working cooperation with each other during assembly, to be movable in at least a first and a second dimension, enabling the position of the first attachment member to be adjusted with respect to the position of the second attachment member before retaining the first attachment member with respect to the second attachment member in a fixed position. The present invention also relates to a propeller propulsion arrangement comprising at least one such propeller nozzle attachment arrangement, a vessel comprising at least one such propeller propulsion arrangement and a method for attaching a propeller nozzle using the propeller nozzle attachment arrangement. The present invention provides for an arrangement which simplifies the attachment of a propeller nozzle, reducing the tolerances needed during installation and improves the attachment and adjustment procedure. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in greater detail with reference to the

accompanying figures in which;

figure 1 shows a schematic view of a propeller propulsion arrangement in perspective, comprising a gear house, a propeller, a propeller nozzle and three propeller nozzle attachment arrangements;

figure 2 shows a propeller nozzle attachment arrangement in an exploded view;

figure 3a shows a cross section of the propeller attachment arrangement when the propeller nozzle is positioned in a first position, which requires adjustment of the propeller nozzle;

figure 3b shows a parts of the relative position of the first and the second attachment member of the propeller nozzle attachment arrangement, when the propeller nozzle is positioned in the first position;

figure 3c shows parts of the propeller propulsion arrangement when the propeller nozzle is positioned in the first position;

figure 4a shows a cross section of the propeller attachment arrangement when the propeller nozzle is positioned in a second position, which requires adjustment of the propeller nozzle;

figure 4b shows a parts of the relative position of the first and the second attachment member of the propeller nozzle attachment arrangement, when the propeller nozzle is positioned in the second position;

figure 4c shows parts of the propeller propulsion arrangement when the propeller nozzle is positioned in the second position;

figure 5a shows a cross section of the propeller attachment arrangement when the propeller nozzle is positioned in a third position, at which the position of the propeller nozzle has been adjusted to an advantageous position;

figure 5b shows a parts of the relative position of the first and the second attachment member of the propeller nozzle attachment arrangement, when the propeller nozzle is positioned in the third position;

figure 5c shows parts of the propeller propulsion arrangement when the propeller nozzle is positioned in the third position;

figure 6a shows a schematic cross section of the first attachment member and;

figure 6b shows a schematic cross section of the second attachment member.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a propeller propulsion arrangement 1 for a vessel (not shown), such a floating vessel, a ship or the like. The propeller propulsion arrangement 1 is adapted to be attached to the vessel at an attachment section 2 arranged on a gear house 3 via a plurality of screws. A propeller nozzle 10 is arranged to substantially encircle a propeller 4 to provide an increased propulsion force, especially at low speed of the vessel.

The propeller nozzle 10 comprises three propeller nozzle attachment arrangements 11 (of which only one is shown in figure 1 ), in the shown embodiment, arranged symmetrically around the periphery of the propeller nozzle 10 with an angle of about 120 degrees and with respect to the centre axis A of the propeller nozzle 10. Although it should be noted that the propeller nozzle attachment arrangements 11 can be arranged according to other configurations, e.g. asymmetrically. The propeller 4 rotates around the centre axis A. The propeller 4 comprises four propeller blades which can be adjustably attached or fixed to the propeller hub. The centre axis A of the propeller nozzle 10 is aligned with a dimension Z. A dimension X and Y are further illustrated together with the dimension Z by the 5 diagram in figure 1. In the shown embodiment, the propeller nozzle attachment

arrangements 1 1 attach the propeller nozzle 10 to the gear house 3. Optionally the propeller nozzle can be attached to any other appropriate part of the propeller propulsion arrangement 1 or the parts of the vessel.

10 Each of the propeller nozzle attachment arrangements 11 comprises a first and a second attachment member 30, 50. Below, only one propeller nozzle attachment arrangements 11 will be described but it should be noted that a plurality of propeller nozzle attachment arrangements 1 1 can be used on a propeller propulsion arrangement 1 , for instance 2, 3, 4, 5, 6, 7, 8, 9, 10 or more. Further, a vessel may be arranged with one or more propeller

15 propulsion arrangements 1 , for instance, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, optionally 10 or more. In the shown embodiment in figure 1 , two of the propeller nozzle attachment arrangements 11 are arranged to the gear house 3 via an intermediate member 12, while one is arranged directly to the gear house 3.

20

Figure 2 shows the propeller nozzle attachment arrangement 11 with an exploded view, in perspective and in greater detail. Parts of the propeller nozzle 10, the intermediate member 12 is shown. A screw 15 is arranged to the intermediate member 12 at a first end 13 of the intermediate member 12. The screw 15 extends through an attachment aperture

25 16 of the propeller nozzle 10 and is attached to the propeller nozzle 10 by means of a nut 17. The first attachment member 30 and the second attachment member 50 are threaded onto the screw 15 during assembly and attachment of the propeller nozzle 10 to the gear house 3. As is visible in figure 2, the first attachment member 30 comprises a substantially hemispherical recess, while the second attachment member 50 comprises a substantially

30 hemispherical protrusion; both are arranged in working cooperation to adjust the position of the propeller nozzle 10 during assembly of the propeller propulsion arrangement 1 , as will be described in greater detail below. The term assembly may include maintenance, adjustment, or other operations. Figures 3a-5c shows; a cross section of the first and the second attachment member 30, 50; the first and the second attachment member 30, 50 as seen along a centre axis C ₁ and; the propeller nozzle 10 and the propeller 4, in corresponding configurations. The centre axis C ₁ being centre axis C ₁ of the first attachment member 30.

Figure 3a shows the first and the second attachment members 30, 50 in a first position. The first position, as can be seen in figure 3c, corresponds to a position in which the propeller nozzle 10 is misaligned with respect to the propeller 4. As the propeller nozzle 10 is displaced, the propeller 4 is subjected to increased cavitations and wear. During operation of the vessel, such a position of the propeller nozzle 10 can be devastating for the propeller propulsion arrangements 1 performance and integrity.

The first attachment member 30, which exhibits a centre axis C ₁ , is welded to the propeller nozzle 10; however it can be an integrated part of the propeller nozzle 10. The first attachment member 30 comprises a first and a second end 31 , 32. A through hole 33 extends through the first attachment member 30 and exits in a recess 34 arranged at the second end 32 of the first attachment member 30.

Retaining means, in the form of a retaining member, in this case a screw 15 is connecting the gear house 3 with the propeller nozzle 10 and keeps it in a fixed position after tightening. As is noticed, the diameter di of the through hole 33 is larger than the diameter d _s of the screw 15. The diameter ά _ϊ of the through hole 33 is in the order of about 25 % larger than the diameter of the d _s of the screw 15, e.g. between 12-125 mm. Optionally the diameter di of the through hole 33 of the first attachment member 30 is in the order of 1 ,2 - 2,5 times the diameter d _s of the retaining member, in this case the screw 15. As this will permit the first attachment member 30, and thereby the propeller nozzle 10, to be moved with respect to the second attachment member 50, and thereby the propeller and the gear house 3 to adjust the position of the propeller nozzle 10 with respect to the propeller 4.

The recess 34 is substantially hemispherical in its form even when exhibiting the through hole 33, for the purpose of this invention, i.e. the cross section exhibits a substantially concave form, and is arranged to receive parts of the second attachment member 50 having a protrusion with a substantially corresponding hemispherical form, and as is noticed, a cross section with a substantially convex form. As is shown in figure 3a and 4a, the recess 34 is eccentrically positioned with respect to the centre axis C ₁ of the first attachment member 30. As a consequence, the first attachment member 30 can be displaced with respect to the second attachment member 50, which the first attachment member 30 is in working cooperation with. This is further illustrated in figures 3b and 3c.

Figure 3b shows the first attachment member 30 and the through aperture 33. Further parts of the second attachment member 50 can be seen in the background. As is noticed, the centre axis C ₁ of the first attachment member 30 and the centre axis C ₂ of the second attachment member 50 are displaced with respect to each other. As a consequence, the position of the propeller nozzle 10 is displaced with respect to the propeller 4, as shown in figure 3c.

A similar displacement, although another extreme, is shown in the figures 4a-4c. Hence, the propeller nozzle 10 can be displaced at least between these extremes, as shown in figures 3a-4c. Figure 4a, shows the first and the second attachment members 30, 50 in a second position. The second position, as can be seen in figure 4c, corresponds to a position in which the propeller nozzle 10 is misaligned with respect to the propeller 4, although to the opposite end of the propeller 4 as compared with figure 3c. The second attachment member 50, as shown in figure 3a and 4a will hereafter be described with reference to figure 4a, is welded on the intermediate member 12, however it can be welded on the gear house 3 of the vessel, or be formed as an integrated part of the gear house 3 for example. As mentioned both the first and the second members 30, 50 can optionally be welded to the corresponding part of the vessel or be an integrated part. However, it is very advantageous if both the first and the second attachment member 30, 50 are separate and movably attached by means of the retaining means, as this enables them to be turned during adjustment of the propeller nozzle 10 and thereby enable the propeller nozzle 10 to be adjusted over a larger distance, reducing even more the need for exact tolerances during e.g. manufacturing or installation of the propeller nozzle 10 or e,g., the gear house. Hence at least one of the first or second attachment members 30, 50 should be movably attached, preferably both. The first and the second attachment members 30, 50 should thus be able to turn around its own centre axis C ₁ , C ₂ . The second attachment member 50 comprises a first and a second end 51 , 52. A centre axis C ₂ extends in the centre of the second attachment member 50. The centre axis C ₂ of the second attachment member 50 is substantially aligned with the centre axis C _s of the screw 15. A through hole 53 extends through the second attachment member 50 and 5 exits in a protrusion 54 arranged at the first end 51 of the second attachment member 50. The protrusion 54 of the second attachment member 50 exhibits a corresponding form to the recess 34 of the first attachment member 30, i.e. a substantially hemispherical form albeit for the through hole 53. The protrusion 54 is further eccentrically positioned with respect to the centre axis C ₂ of the second attachment member 50.

10

The diameter d ₂ of the through hole 53 is in the order of 10-100 mm, preferably 20-80 mm. As is noticed, the diameter d ₂ of the through hole 53 of the second attachment member 50 is just slightly larger than the diameter d _s of the screw 15 enabling a snugly fit of the retaining member, in this case the screw 15. Optionally, the diameter di of the

15 through hole 33 of the first attachment member 30 is in the order of d ₂ of the through hole 53 + the offset D 1 +D3.

The protrusion 54 is substantially hemispherical in its form, i.e. the cross section exhibits a substantially convex form, and is arranged to enter and be received by parts of the recess

20 34 of the first attachment member 30, which recess 34 exhibits a substantially

corresponding hemispherical form. Hence the first and the second attachment members 30, 50 are equipped with either a recess or a protrusion of corresponding form enabling the first and the second attachment members 30, 50 to be arranged in working

cooperation.

25

Following figures 5a-5c, the propeller nozzle 10 has been centred with respect to the propeller 4. First and second attachment member 30, 50 will be described in greater detail with reference to figure 6a-6b which shows schematic cross sections of the first and the second attachment members 30, 50. Starting with the first attachment member 30,

30 according to an embodiment of the present invention, the recess 34 has a substantially hemispherical form with a radius R1 as shown in the figure 5a. The origin of the hemisphere O is however offset a distance D1 from the centre axis C ₁ of the first attachment member 30, and a distance D2 from the second end 32 of the first attachment member 30. The offset of the origin of the hemisphere O from the second end 32 of the

35 first attachment member 30 is away from the first and second end 31 , 32 as indicated in figure 5a The offset of the origin of the hemisphere O provides for an eccentric position of the recess 34, with respect to the first attachment member 30 and especially the centre axis C ₁ of the first attachment member 30 The radius R1 of the recess 34 is

advantageously in the order of 1 ,0-3,5 times the diameter Cl ₁ of the through hole 33 The opening OP of the recess 34 is advantageously 1 ,5-2,5 times the diameter d-i of the through hole 33 The recess 34 exhibits a contact surface 35 which after assembly is intended to contact a corresponding contact surface 55 of the second attachment member

50 A circumferential flange 37 extends around the periphery of the first attachment member 30 The circumferential flange 37 is advantageously used to attach the first attachment member 30 to the propeller nozzle 10

According to an embodiment of the present invention, the protrusion 54 of the second attachment member 50, exhibit a hemispherical form with a radius R2 The origin of the hemisphere 02 can be offset a distance D3 from the centre axis C ₂ , and a distance D4 from the first end 51 of the second attachment member 50 However, in the shown embodiment, the distance D4 is zero, and thereby substantially aligned with the first end

51 of the second attachment member 50 As has been described, this offset enables the second attachment member 50 to be moved with respect to the first attachment member 30 in at least two dimensions, i e the X and the Y dimension In the shown embodiment, the first attachment member is moved in three dimensions, i e X, Y, Z, to thereby adjust the position of the propeller nozzle 10 with respect to the propeller 4 The offset of the origin of the hemisphere 02 provides for an eccentric position of the protrusion 54, and in this case the projecting hemisphere, with respect to the second attachment member 50 and especially the centre axis C ₂ of the second attachment member 50

It should be noted that the offset D1 and the offset D3 as shown in figures 6a-6b are preferably substantially equal or optionally identical, this teaching is appropriate for all embodiments described herein As mentioned, the diameter d ₂ of the through hole 53 is in the order of 10-100 mm, preferably 20-80 mm Optionally, the diameter d-i of the through hole 33 of the first attachment member 30 is in the order of d ₂ of the through hole 53 + the offset D1+D3 For example if the propeller 4 comprises a diameter of 2,6 meter the retaining member 15 is adapted for an M36 nut thread, the offset D1 is in the order of 5 mm and the offset D3 is in the order of 5 mm The total eccentricity is about 10 mm For a propeller with a diameter of about 1 ,3 meter each offset is about 2,5 mm, and for a propeller diameter of about 5,2 m each offset is about 10 mm The radius R2 of the protrusion 54 is advantageously in the order of 1 ,0-3,5 times the diameter di of the through hole 33 of the first attachment member 30. At least parts of the surface 55 of the protrusion 54 provides for a contact surface 56 which after assembly is intended to contact the corresponding contact surface 34 of the first attachment member 30. A circumferential flange 57 extends around the periphery of the second attachment member 50. The circumferential flange 57 is advantageously used to attach the second attachment member 50 to the gear house 3. The contact surfaces 33 of the recess 34 of the first attachment member 30 and the contact surface 53 of the protrusion 54 of the second attachment member 50 comprises a smooth surface, enabling a continuous adjustment of the first attachment member with respect to the second attachment member across the available contact surface.

Optionally, the contact surfaces 33, 53 can be arranged with a structured surface such as protrusions or grooves, enabling a stepwise adjustment across the available contact surface. A stepwise adjustment may be advantageous as it can simplify the adjustment of a heavy propeller nozzle, enabling a propeller nozzle to be kept in a certain position without tightening the retaining member fully due to the structured surfaces.