TECHNICAL FIELD

Embodiments herein relate to propeller arrangements, and in particular to propeller arrangements comprising a propeller, a propeller shaft assembly comprising a shaft portion extending from a distal side of the propeller, a support member arranged to be connected to a hull of the marine vessel, and a bearing arrangement interconnecting the support member and the shaft portion.

BACKGROUND

Marine vessels, such as cargo vessels, supply vessels, navy marine vessels and pleasure vessels, of today are generally furnished with a propulsion system with a propeller connected to an engine of the vessel via a shaft assembly which is supported in a stern tube of the vessel by means of at least one bearing.

The bearings support the weight of the propeller shaft and of the propeller. In many large marine vessels, the propellers used are very large and heavy, and the bearings as well as the other parts of the propeller arrangements are subjected to great strain, such as torsional and bending stress, during operation of the propeller arrangement.

In particular, the torsional stress exerted to the different components of the propeller arrangements during operation are challenging, and the different components of the propeller arrangements have to be designed and constructed in a way to cope with the torsional stress. This often leads to complex designs of the different components.

In general, operating very large propellers at low rotational speeds is particularly demanding to the bearings supporting the propeller shaft assembly. As an example, continuously operating a propeller having a diameter of at least six meters at less than 10 revolutions per minute is considered operating a large propeller at a low rotational speed. Common problems with known arrangements are bearing fatigue damage and shaft elements fatigue life reduction.

As such, there is a need for improvements of the prior art propeller arrangements. SUMMARY

In view of the discussion above, it is an object for embodiments herein to provide a propeller arrangement which addresses one or more of the above drawbacks, or which provides for a useful alternative.

According to a first aspect, the object is at least partially achieved by means of a propeller arrangement for a marine vessel, which propeller arrangement comprises a propeller, a propeller shaft assembly comprising a shaft portion extending from a distal side of the propeller, a support member arranged to be connected to a hull of the marine vessel, and a bearing arrangement interconnecting the support member and the shaft portion. The support member comprises at least one cooling fluid conduit for accommodating and circulating a first cooling fluid within the support member and further to the shaft portion and/or to the bearing arrangement. The provision of a support member implies that a bearing for supporting the shaft assembly is positioned outside of the torsional domain of the propeller arrangement, and the load exerted to other bearings of the propeller arrangement is reduced. Thanks to the possibility to cool down the first cooling fluid by means of circulating it within the support member, the first cooling fluid the first cooling fluid itself is cooled in an efficient way, and can also cool the bearing arrangement efficiently. Therefore the risk of burning of the bearing is reduced.

According to an embodiment of the first aspect the shaft portion is tubular and comprises at least one passage for guiding the first cooling fluid from an interior space of the shaft portion to the bearing arrangement, so as to allow the first cooling fluid to lubricate the bearing arrangement. The use of one single fluid as booth lubricant and cooling fluid for the bearing results in a simplified arrangement in which the risk for overheating of the lubricant is reduced. The temperature of the lubricant is important to bearing functionality e.g. because the viscosity of the lubricant depends on its temperature, and keeping the lubricant at a low temperature is thus very profitable. According to this embodiment, the bearing lubrication fluid can be kept at low temperature where its viscosity is maintained sufficiently high for allowing the bearing to work in a hydrodynamic mode. Operating a large propeller at a low rotational speed, which in general results high stresses exerted to the different components of the propeller arrangements and heating of the bearing lubrication fluid, is thereby facilitated. The minimum allowed running speed of large propellers may therefore be reduced.

According to an embodiment of the first aspect the bearing arrangement has a housing comprising at least one channel for guiding a second cooling fluid through the bearing housing. Thereby, a second cooling system for the bearing is achieved such that the bearing is cooled in a two-stage manner. This results in an even more efficient cooling, and a reduced risk for burning of the bearing.

According to an embodiment of the first aspect the at least one channel has an inlet arranged to receive the second cooling fluid from an exterior of the housing. Thereby, ambient water may be used as a second cooling fluid.

According to an embodiment of the first aspect the support member comprises means for monitoring and/or controlling the load subjected to the bearing arrangement. Since the support structure is connected to the hull, the load subjected to the bearing arrangement can thus be monitored and/or controlled without docking the vessel.

According to an embodiment of the first aspect the propeller arrangement comprises a pitch changing mechanism for controlling the pitch settings of at least one propeller blade of the propeller, and a hydraulic fluid distribution unit arranged to supply a hydraulic fluid to the pitch changing mechanism from the distal side of the propeller. Thereby, arrangements comprising controllable pitch propellers having the advantages of the first aspect can be manufactured in a simple way, taking profit of the support member. When the hydraulic fluid distribution unit is positioned in that way, it is not subjected to the torsional stresses that it would have been if positioned somewhere between the propeller and the main engine.

According to an embodiment of the first aspect the hydraulic fluid distribution unit is arranged to supply the first cooling fluid to the pitch changing mechanism. Thereby, a simplified arrangement is achieved.

According to an embodiment of the first aspect the support member is part of one of a rudder stock, a hydrofoil bracket or a propeller nozzle of the marine vessel. Thereby, one single component may have several functions, resulting in a simplified arrangement which may be manufactured in a cost-efficient way

According to a second aspect, the object is at least partially achieved by means of a propeller arrangement comprising a propeller having a hub and at least one propeller blade connected to the hub, the propeller being adapted to be connected to a shaft assembly via a proximal side of the propeller, and a pitch changing mechanism for controlling the pitch settings of the at least one propeller blade. The pitch changing mechanism is operating said pitch settings of the at least one propeller blade via a distal side of the propeller, which distal side is positioned opposite to the proximal side.

According to an embodiment of the second aspect the propeller arrangement comprises a hydraulic fluid distribution unit adapted to supply a hydraulic fluid to the pitch changing mechanism at a distal side of the propeller. Thereby, the shaft assembly does not have to accommodate pipes for conveying hydraulic fluid from the hydraulic fluid distribution unit to the pitch changing mechanism, and may have a more simple construction than what is the case for prior art arrangements.

According to an embodiment of the second aspect the propeller arrangement comprises a propeller shaft assembly comprising a shaft portion extending from a distal side of the propeller, a support member arranged to be connected to a hull of a marine vessel, and a bearing arrangement interconnecting the support member and the shaft portion. The presence of a support structure ensures that deflection of the shaft is minimized and the life of the bearings may be prolonged. Furthermore, the presence of a support structure enables moving the hydraulic fluid distribution unit out of the torsional domain. Thereby, the hydraulic fluid distribution unit may have a simpler construction, than if it would have been positioned between the propeller and the engine of the vessel. This simpler construction does not have to take torsional vibrations into consideration.

According to an embodiment of the second aspect the support member comprises at least one cooling fluid conduit for accommodating and circulating a first cooling fluid within the support member and further to the shaft portion and/or to the bearing arrangement.

Thanks to the possibility to cool down the lubrication fluid of this bearing by means of circulating it within the support member, the lubrication fluid will not become too warm, and the risk of burning of the bearing is reduced. The lubrication fluid can be kept at low temperature where its viscosity is maintained sufficiently high for allowing the bearing to work in a hydrodynamic mode.

According to an embodiment of the second aspect the shaft portion is tubular and comprises at least one passage for guiding the first cooling fluid from an interior space of the shaft portion to the bearing arrangement, so as to allow the first cooling fluid to lubricate the bearing arrangement. Moreover the use of one single fluid as booth lubricant and cooling fluid for the bearing results in a simplified arrangement, in which the risk for overheating of the lubricant is reduced.

According to an embodiment of the second aspect the bearing arrangement has a housing comprising at least one channel for guiding a second cooling fluid through the bearing housing. Thereby, a second cooling system for the bearing is achieved such that the bearing is cooled in a two-stage manner. This results in an even more efficient cooling, and a reduced risk for burning of the bearing.

According to an embodiment of the second aspect the support member accommodates a controlling unit for manually controlling the pitch settings of the at least one propeller blade. Since the support member is connected to the hull, this makes it possible to manually control the pitch settings of the propeller in emergency situations and/or in case of breakdown of the hydraulic system for changing the pitch settings. Then it is possible sail safely to nearest harbor without towing the vessel.

According to an embodiment of the second aspect the support member is part of one of a rudder stock, a hydrofoil bracket or a propeller nozzle of the marine vessel. Thereby, one single component may have several functions, resulting in a simplified arrangement which may be manufactured in a cost-efficient way.

According to embodiments herein, the propeller arrangement is a propulsion

arrangement.

According to third aspect, the object is at least partially achieved by means of a marine vessel comprising a propeller arrangement according to any the first two aspects. The advantages and benefits of a marine vehicle according to the third aspect are the same as for the first two aspects. BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments herein will be described in greater detail by way of example only with reference to attached drawings, in which

Fig. 1 is a schematic side view of a propeller arrangement according to a first

embodiment.

Fig. 2 is a detail view of a portion of the arrangement shown in Fig. 1.

Fig. 3 is a schematic cross-sectional view, taken along line A-A of Fig. 2. Fig. 4 is a schematic cross-sectional view, taken along line B-B of Fig. 1.

Fig. 5 is a schematic side view of a propeller arrangement according to a second embodiment.

Fig. 6 is a schematic side view of a propeller arrangement according to a third

embodiment. Fig. 7 is a schematic side view of a propeller arrangement according to a fourth embodiment

Fig. 8 is a detail view of a portion of the arrangement shown in Fig. 7.

Fig. 9 is a schematic cross-sectional view, taken along line A-A of Fig. 8, in which view some of the parts shown in Fig. 8 are omitted. Fig. 10 is a schematic cross-sectional view, taken along line B-B of Fig. 7.

Fig. 11 is a schematic side view of a propeller arrangement according to a fifth embodiment.

Fig. 12 is a schematic side view of a propeller arrangement according to a sixth embodiment. Still other objects and features of embodiments herein will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits hereof, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

DEFINITIONS

As used herein the following terms have the following meanings:

The terms "proximal" and "distal" are used with reference to an axial direction of the propeller. The "proximal side" of a propeller is the side receiving the propeller shaft which is in working cooperation with a drive source of the propeller, such as a diesel engine, or an electrical motor. The "distal side" of the propeller is positioned opposite to the proximal side.

In the exemplary embodiments shown in the drawings herein, the proximal side of the propeller is thus the forward side of the propeller, whereas the distal side is the aft side of the propeller.

The "torsional domain" of the propeller arrangement extends from the engine, which is the torque source, to the propeller, which is the torque absorber. DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments herein will be described more fully hereinafter with reference to the accompanying drawings. In the drawings, like numbers refer to like elements.

In Fig. 1 , a rear portion of a marine vessel, with a propeller arrangement 100 according to an embodiment herein is schematically shown. The marine vessel may e.g. be a cargo vessel or a supply vessel.

The propeller arrangement comprises a propeller 110 having a hub 111 and at least one propeller blade 112 extending from the hub 111. The hub may e.g. have a cylindrical, conical or barreled shape. The propeller 110 shown in Fig. 1 comprises four propeller blades 112, extending from the hub 111 , According to some embodiments herein, the propeller diameter, i.e. the diameter of the imaginary circle scribed by the blade tips as the propeller rotates, is at least 4 meters. The propeller has a proximal side 114 extending to a proximal end 116 of the propeller 110, and a distal side 115 extending to a distal end 117 of the propeller 110. In the embodiment shown in Fig. 1 , the proximal end 116 of the propeller 110 is a proximal end of the propeller hub 111 and the distal end 117 of the propeller 110 is a distal end of the hub 111.

The propeller 110 is connected to an engine (only the crank shaft 10 of which is shown) of the marine vessel via a propeller shaft assembly 120 which is supported in a stern tube of the marine vessel. The propeller shaft assembly 120 has a first portion 121 which is positioned adjacent to the proximal end 116 of the propeller 110. This first portion 121 is supported by an aft stem tube bearing 11 and is received in an opening in the proximal end 116 of the propeller hub 111. The propeller shaft assembly 120 extends through the propeller 110 and has a second portion 122 which extends beyond the distal end 117 of the propeller 110.

A bearing arrangement 140 interconnects the second shaft portion 122 and a first end of a support member 130. A second end of the support member is connected to a hull 2 of the vessel. Mounting flanges 139 and a sealing packing may be arranged to secure the support member to the hull 2 in a proper way. As shown in Fig. 1 the support member may be positioned adjacent to a rudder 3 of the vessel. The support member 130 in the embodiment shown in Fig. 1 is not connected to the rudder 3 however. According to other embodiments, such as the one of Fig. 5, the support member is connected to the rudder 3. Since the torsional domain of the propeller arrangement 100 extends from the engine of the vessel to the propeller 110, the bearing arrangement 140 is positioned outside of this torsional domain.

A detail view of the first end of the support member 130 and the bearing arrangement 140 is shown in Fig. 2. The bearing arrangement 140 has a bearing housing 141 which may be integrally formed with the support member 130. A sealing member 126 is arranged between the bearing arrangement 140 and the propeller hub (not shown). The portion of the support member 130 which houses the bearing arrangement 140 may have a variety of shapes, such as a hydrodynamic optimized shape to reduce the water resistance. The second shaft portion 122 is tubular, with and internal space 123 surrounded by a wall 124. The second shaft portion 122 functions as the journal 122 of a journal bearing 140 with a bearing housing 141 surrounding the journal 122.

5 In the following, an arrangement for cooling and lubricating the bearing arrangement 140 by means of a first cooling fluid will be described.

The support member 130 comprises an inlet conduit 131 for transporting a first cooling fluid from the second end of the support member 130 towards the bearing arrangement 10 140. The inlet conduit 131 is shown in Figs. 1 and 2.

The cooling fluid arriving to the interior space 123 of the second shaft portion 122 is used to cool the bearing arrangement 140 from the interior space 123 of the second shaft portion 122.

15

A cross section of the bearing arrangement 140 is shown in Fig. 3. Between the wall 124 of the second shaft portion 122 and the bearing housing 141 there is a lubricant accommodating space 143 arranged to accommodate a lubricating fluid. 0 The wall 124 of the second shaft portion 122 comprises a passage 125. The passage allows the first cooling fluid to pass from the interior space 123 to the lubricant

accommodating space 143 between wall 124 of the second shaft portion 122 and the bearing housing 141. Thereby, the first cooling fluid will also function as a bearing lubricant.

5

As shown in Fig. 1 , there may be a difference in altitude between the bearing

arrangement 140 and a support member receiving portion of the hull 2. The first cooling fluid is heated in the bearing arrangement 140, and the first cooling fluid leaving the bearing arrangement 140 will therefore have a lower density than the first cooling fluid 0 entering the bearing arrangement 140. As long as there is a difference in altitude between the bearing arrangement 140 and a support member receiving portion of the hull 2 the first cooling fluid leaving the bearing arrangement 140 will automatically rise towards the hull, within the support member 130, whereas cooling fluid having a lower temperature and thereby a higher density will descend towards the bearing arrangement 140. A pump

5 assembly (not shown) may be arranged to facilitate circulation of the first cooling fluid. During its passage through the support member 130, the first cooling fluid will be cooled. As shown in Fig. 1 , an outlet conduit 132 may be arranged adjacent to the second end of the support member 130 to allow the cooling fluid to leave the support member 130. The first cooling fluid rising towards the hull 2 within the support member 130 may flow freely within a hollow space 133 defined within the support member 130. When the first cooling fluid has passed through the outlet conduit 132, it will be circulated back towards the bearing arrangement via the inlet conduit 131. The first cooling fluid may flow in a closed circuit. According to some embodiments, the first cooling fluid flows in a closed circuit within the support member 130 and in an area adjacent to the second end of the support member 130.

The first cooling fluid may be oil having a viscosity of at least 50 cSt. The first cooling fluid may have a variety of compositions. According to an embodiment, mineral oil is used, but also other kinds of cooling fluids can be used, as long as they will function properly as lubricants as well.

As shown in Fig. 1 , a bearing adjusting disc 137 may be arranged within or next to the support member 130. The bearing adjusting disc 137 may be used to adjust a vertical position of the bearing arrangement. Furthermore, a load sensor 138 may be arranged within or next to the support member 130, as shown in Fig. 1. The load sensor may be used to monitor the load applied to the bearing arrangement 140. According to some embodiments an arrangement 138 for monitoring as well as controlling the load is used. In the following an arrangement for cooling the bearing arrangement by means of a second cooling fluid will be described.

As shown in Fig. 3, the bearing housing 141 comprises a plurality of passages 142. The passages 142 extend in an axial direction of the bearing housing 141 and are arranged to accommodate a second cooling fluid. The passages 142 may have inlets arranged to receive the second cooling fluid incoming from an exterior of the bearing arrangement 140. Correspondingly, the passages may have outlets for discharging the first cooling fluid to the exterior of the bearing arrangement 140. The cooling arrangement achieved by means of the passages 142 will then be an open circuit arrangement. When the propeller 100 is submersed into water and rotates, ambient water may enter into the passages 142 automatically. Guiding means may be provided to facilitate guiding of water towards the inlets.

A second embodiment is shown in Fig. 5. The embodiment shown in Fig. 5 differs from the embodiment of Fig. 1 in the configuration of the support member 130. The support member 130 shown in Fig. 5 is connected to a non-rotating part or the rudder 3. The non- rotating part of the rudder is connected to a rudder stock. According to other

embodiments, the support member 130 is connected to the rudder stock or is integrally formed with the rudder stock.

A third embodiment is shown in Fig. 6. In the embodiment shown in Fig. 6, the support member 130 is part of a propeller nozzle.

In Fig. 7, a rear portion of a marine vessel, with a propeller arrangement 100 according to an embodiment herein is schematically shown. The marine vessel may e.g. be a cargo vessel or a supply vessel. The propeller arrangement comprises a propeller 110 having a hub 111 and at least one propeller blade 112 extending from the hub 111. The hub may e.g. have a cylindrical, conical or barreled shape. The propeller 110 shown in Fig. 7 comprises four propeller blades 112, extending from the hub 111. According to some embodiments herein, the propeller diameter, i.e. the diameter of the imaginary circle scribed by the blade tips as the propeller rotates, is at least 4 meters.

The propeller has a proximal side 114 extending to a proximal end 116 of the propeller 110, and a distal side 115 extending to a distal end 117 of the propeller. In the

embodiment shown in Fig. 7, the proximal end 116 of the propeller 110 is a proximal end of the propeller hub 111 and the distal end 117 of the propeller 110 is a distal end of the hub 111.

The propeller 110 is connected to an engine (only the crank shaft 10 of which is shown) of the marine vessel via a propeller shaft assembly 120 which is supported in a stern tube of the marine vessel. The propeller shaft assembly 120 has a first portion 121 which is positioned adjacent to the proximal end 116 of the propeller 110. This first portion 121 is supported by an aft stern tube bearing 11 and is received in an opening in the proximal The propeller shaft assembly 120 extends through the propeller 110 and has a second portion 122 which extends beyond the distal end 117 of the propeller 110.

A bearing arrangement 140 interconnects the second shaft portion 122 and a first end of a support member 130. A second end of the support member is connected to a hull 2 of the vessel. Mounting flanges 139 and a sealing packing may be arranged to secure the support member to the hull 2 in a proper way. As shown in Fig. 7 the support member may be positioned adjacent to a rudder 3 of the vessel. The support member 130 in the embodiment shown in Fig. 7 is not connected to the rudder 3 however. Since the torsional domain of the propeller arrangement 100 extends from the engine of the vessel to the propeller 110, the bearing arrangement 140 is positioned outside of this torsional domain.

A detail view of the first end of the support member 130 and the bearing arrangement 140 is shown in Fig. 8. The bearing arrangement 140 has a bearing housing 141 which may be integrally formed with the support member 130. A sealing member 126 is arranged between the bearing arrangement 140 and the propeller hub (not shown). The portion of the support member 130 which houses the bearing arrangement 140 may have a variety of shapes, such as a hydrodynamic optimized shape to reduce the water resistance. The second shaft portion 122 is tubular, with and internal space 123 surrounded by a wall 124. The second shaft portion 122 functions as the journal 122 of a journal bearing 140 with a bearing housing 141 surrounding the journal 122.

The propeller 110 shown in Fig. 7 is a controllable pitch propeller. The propeller arrangement 100 comprises a hydraulic pitch changing mechanism 150 arranged to change the pitch settings of the propeller blades 112. The pitch changing mechanism 150 is shown in Fig. 8. In Fig. 8, a hydraulic fluid distribution unit 160 arranged to distribute hydraulic fluid to the pitch changing mechanism 150 is also indicated. The hydraulic fluid distribution unit 160 in this embodiment is an oil distribution (OD) box.

According to the embodiment shown in Fig. 8, the hydraulic fluid distribution unit 160 is arranged within the support member 130, aft of the bearing arrangement 140. Thereby, it is positioned out of the torsional domain of the propeller arrangement. In many known arrangements, the hydraulic fluid distribution unit 160 is positioned adjacent to the propeller shaft assembly 120 somewhere between the propeller 110 and the engine of the vessel, i.e. in the torsional domain. Then, the hydraulic fluid distribution unit 160 has to be designed so as to cope with the torsional vibration stress subjected to it, and the propeller shaft assembly must comprise conduits for leading the hydraulic fluid from the hydraulic fluid distribution unit to the propeller.

When the hydraulic fluid distribution unit 160 is positioned as indicated in Fig. 7, the propeller shaft assembly 120 does not have to comprise any hydraulic fluid conduits, and may be designed in a simpler and more robust way. Thereby, more cost-efficient propeller arrangement may be manufactured. Designing the shaft assembly in a more robust way may prolong the life time of the shaft assembly.

Furthermore, due to its position outside the torsional domain, the hydraulic fluid distribution unit 160 according to embodiments herein is not subjected to the torsional stress which is subjected to hydraulic fluid distribution units of known arrangements. Since the effect of torsional stress does thus not have to be taken into account when designing the hydraulic fluid distribution member 160 according to embodiments herein it can be designed in a simpler and more cost efficient way, than what is the case for known arrangements.

The support member 130 may comprise hydraulic pitch control pipes 151 used to transport hydraulic fluid to and from the hydraulic fluid distribution unit 160 and/or the pitch changing mechanism 150. The hydraulic pitch control pipes 151 are indicated in Figs. 7, 8 and 10.

The support member may comprise a controlling unit 136 for manually controlling the pitch settings of the at least one propeller blade 112. Since the support member is connected to the hull 2, this makes it possible to manually control the pitch settings of the propeller in emergency situations and/or in case of breakdown of the hydraulic pitch changing mechanism 150. The controlling unit 136 may comprise wires used to manually change the pitch settings. Such wires are indicated in Figs. 8 and 10.

The propeller arrangement with a controllable pitch propeller according to the above description may also comprise a cooling arrangement as described below. The support member 130 comprises an inlet conduit 131 for transporting a first cooling fluid from the second end of the support member 130 towards the bearing arrangement 140. The inlet conduit 131 is shown in Figs. 7 and 8.

The cooling fluid arriving to the interior space 123 of the second shaft portion 122 is used to cool the bearing arrangement 140 from the interior space 123 of the second shaft portion 122. A cross section of the bearing arrangement 140 is shown in Fig. 9. Between the wall 124 of the second shaft portion 122 and the bearing housing 141 there is a lubricant accommodating space 143 arranged to accommodate a lubricating fluid.

The wall 124 of the second shaft portion 122 comprises a passage 125. The passage allows the first cooling fluid to pass from the interior space 123 to the lubricant

accommodating space 143 between wall 124 of the second shaft portion 122 and the bearing housing 141. Thereby, the first cooling fluid will also function as a bearing lubricant. As shown in Fig. 7, there may be a difference in altitude between the bearing

arrangement 140 and a support member receiving portion of the hull 2.The first cooling fluid is heated in the bearing arrangement 140, and the first cooling fluid leaving the bearing arrangement 140 will therefore have a lower density than the first cooling fluid entering the bearing arrangement 140. As long as there is a difference in altitude between the bearing arrangement 140 and a support member receiving portion of the hull 2 the first cooling fluid leaving the bearing arrangement 140 will automatically rise towards the hull, within the support member 130, whereas cooling fluid having a lower temperature and thereby a higher density will descend towards the bearing arrangement 140. A pump assembly (not shown) may be arranged to facilitate circulation of the first cooling fluid.

During its passage through the support member 130, the first cooling fluid will be cooled. As shown in Fig. 7, an outlet conduit 132 may be arranged adjacent to the second end of the support member 130 to allow the cooling fluid to leave the support member 130. The first cooling fluid rising towards the hull 2 within the support member 130 may flow freely within a hollow space 133 defined within the support member 130. When the first cooling fluid has passed through the outlet conduit 132, it will be circulated back towards the bearing arrangement via the inlet conduit 131. The first cooling fluid may flow in a closed circuit. According to some embodiments, the first cooling fluid flows in a closed circuit within the support member 130 and in an area adjacent to the second end of the support member 130.

The first cooling fluid may be oil having a viscosity of at least 50 cSt. The first cooling fluid may have a variety of compositions. According to an embodiment, mineral oil is used, but also other kinds of cooling fluids can be used, as long as they will function properly as lubricants as well.

As shown in Fig. 9, the bearing housing 141 comprises a plurality of passages 142. The passages 142 extend in an axial direction of the bearing housing 141 and are arranged to accommodate a second cooling fluid. The passages 142 may have inlets arranged to receive the second cooling fluid incoming from an exterior of the bearing arrangement 140. Correspondingly, the passages may have outlets for discharging the first cooling fluid to the exterior of the bearing arrangement 140. The cooling arrangement achieved by means of the passages 142 will then be an open circuit arrangement. When the propeller 100 is submersed into water and rotates, ambient water may enter into the passages 142 automatically. Guiding means may be provided to facilitate guiding of water towards the inlets.

Another embodiment is shown in Fig. 11. The embodiment shown in Fig. 11 differs from the embodiment of Fig. 7 in the configuration of the support member 130. The support member 130 shown in Fig. 11 is connected to a non-rotating part or the rudder 3. The non-rotating part of the rudder is connected to a rudder stock. According to other embodiments, the support member is integrally formed with the rudder stock.

Another embodiment is shown in Fig. 12. In the embodiment shown in Fig. 12, the support member 130 is part of a propeller nozzle.

According to some embodiments, the hydraulic fluid used by the pitch changing mechanism 150 is the same fluid as the first cooling fluid described above. This integration of several systems facilitates manufacturing of a compact and simple propeller arrangement. The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the invention, which is defined by the appending claims.