Ship comprising a rudder system

Abstract

The present invention relates to a ship, comprising: - a propeller that is driveably connected to a drive; - a rudder system arranged downstream of the propeller and comprising a pair of rudders arranged on opposite sides relative to a water flow induced by the propeller and configured to jointly deflect the water flow induced by the propeller; - wherein each rudder of the pair of rudders comprises two flaps that are pivotable relative to each other between a forward sailing state and a reversing state; and - wherein, in the reversing state, said flaps are oriented to define a scoop shape of the rudders to deflect and reverse the water flow.

Description

[0001] The present invention relates to a ship, comprising a propeller that is driveably connected to a drive, and a rudder system arranged downstream of the propeller and comprising at least one rudder configured to deflect a water flow induced by the propeller. The invention further relates to such a rudder system.

[0002] Rudder systems are used to steer a ship, i.e. adjust the course of a moving ship. The rudders may be used to maintain a substantially straight course, or to steer and change the direction of movement of the ship.

[0003] When a ship is moving in a forward direction and wants to decelerate, i.e. brake, the driving direction of the propeller may be reversed. In this way, the drive may cause a driving force that is directed in a driving direction opposite a direction of movement of the ship, thereby counteracting the actual movement of the ship and effectively decelerating the ship. Once a forward moving ship has come to a standstill, and if the driving direction of the propeller is maintained in correspondence to a rearward directed driving force, the ship will start to accelerate and move in the rearward direction. Thus, by changing the driving direction of the propeller, a moving ship may be slowed down effectively to a standstill, and may successively be moved in an opposite direction. In order to reverse the driving direction of the propeller, ships need a reversing gear.

[0004] Although ships with a reversing gear are able to reverse the driving direction of the propeller and thereby cause a forward deceleration, i.e. braking, of the ship that allows the ship to come to a standstill significantly faster than a ship that decelerates solely by its natural drag or deliberately increased drag, there are also some disadvantages associated with ships that comprise a reversing gear.

[0005] First of all, a reversing gear adds to the complexity of the driving system. Furthermore, reversing the driving direction of the propeller takes precious time, which may not be available during an emergency brake. In general, the faster a ship is able to decelerate / brake, the safer the ship is.

[0006] The Japanese patent application JP 2016 037270 A discloses a ship wherein the driving direction of the propeller may be changed to slow down or reverse the movement direction of the ship, and thus applies to a ship having a reversing gear as described in the previous paragraph. JP 2016 037270 A however also acknowledges that reversing the driving direction of the propeller takes precious time, and therefore proposes to apply a rudder system having two rudders that are arranged on opposite sides relative to a water flow induced by the propeller, said two rudders being pivotable symmetrically about the ship axis in opposite directions to each other to reduce the time for which the propeller is turning in inertia after stopping driving the propeller when a sudden stop is necessary, such as during an emergency brake, and to enable the propeller to start reversing quickly.

[0007] DE 25 10 256 B1, which is considered the closest prior art, discloses a ship, comprising a propeller that is driveably connected to a drive, and a rudder system arranged downstream of the propeller and comprising a pair of rudders arranged on opposite sides relative to a water flow induced by the propeller and configured to jointly deflect the water flow induced by the propeller. Relative to this document, at least the features of the characterizing portion of claim 1 are novel.

[0008] JP H04 358993 A, NL 7014527 and GB 422 938 A, which are acknowledged as further prior art, are all related to rudders that are to be applied as a single rudder of a ship, wherein said single rudder is positioned directly downstream of a propeller, i.e. centrally arranged in the water flow induced by said propeller.

[0009] An objective of the present invention is to provide a rudder system for a ship, that is improved relative to the prior art and wherein at least one of the above stated problems is obviated or alleviated.

[0010] Said objective is achieved with the rudder system according to claim 1.

[0011] By virtue of the two flaps being pivotable relative to each other, the orientation of these two flaps relative to each other is adjustable to thereby control a deflection of the water flow induced by the propeller. By effectively and gradually deflecting the flow path of the water flow, a high efficiency may be obtained. Conventional rudder systems, such as described in the aforementioned prior art documents DE 25 10 256 B1, JP H04 358993 A and NL 7014527, experience significant energy losses due to the different nature of these systems. After all, they fail to deflect the water flow in a gradual manner. Instead, they all block the flow stream induced by the propeller, thereby causing a pressure build up. The water will then start to flow to the direction of least resistance, i.e. to the sides and partially in a forward direction, thereby pushing the ship in rearward direction. The accompanying turbulence however causes significant energy losses. In DE 25 10 256 B1, the flow stream induced by the propeller is blocked by two adjacent rudders pointing towards each other. In the single rudder systems of JP H04 358993 A and NL 7014527, a similar blocking is obtained by the straight flaps of these rudders systems being arranged in a V-shape. Such a V-shape will never be able to gradually deflect the water flow induced by the propeller. Experiments with a prototype of the present invention showed a pure deflection of the water flow induced by the propeller, with almost no turbulence, and a promising efficiency.

[0012] By orienting the flaps of the rudders to define a scoop shape, the water flow induced by the propeller may be deflected and reversed. The driving direction of the propeller may thus be unchanged, while the driving force is effectively reversed by said scoop shaped rudder. In this way, the ship is capable of effectively causing a forward deceleration or rearward propulsion of said ship, while there is no need for a conventional reversing gear. Besides the absence of a conventional reversing gear resulting in a simple and robust driving system, an even more important advantage is that the time required to reverse the driving force of the ship is significantly reduced. Consequently, the ship may decelerate / brake extremely fast, thereby improving safety and user comfort.

[0013] Moreover, a rudder system having a pair of rudders offers greatly improved maneuverability relative to rudder systems having a single rudder, because it may effectively direct substantially the whole water flow induced by the propeller. According to the present invention having rudders with two flaps, this improved maneuverability is obtained both in the forward sailing state and the reversing state.

[0014] According to a preferred embodiment, the rudder system is configured to deflect the water flow and steer the ship in the forward sailing state, and to deflect and reverse the water flow in the reversing state to cause a forward deceleration or rearward propulsion of said ship.

[0015] According to a further preferred embodiment, the two rudders are pivotable relative to each other and configured to rotate in the same direction relative to the ship to deflect the water flow and steer the ship during forward propulsion thereof in the forward sailing state, and to rotate in an opposite direction relative to the ship to deflect and reverse the water flow during forward deceleration or rearward propulsion of said ship in the reversing state.

[0016] According to an even further preferred embodiment, at least one of the two flaps of each rudder, and even more preferably each of the two flaps of each rudder, comprises an asymmetrical cross section in top view to define a rudder shape that is configured to bend the water flow induced by the propeller in the reversing state. Such an asymmetrical shape may be defined by an outer side of at least one of the two flaps of each rudder, and even more preferably an outer side of each of the two flaps of each rudder, that is directed towards the propeller in the reversing state, comprising a non-straight shape. For example, the outer side of the flap may comprise two or more straight sections that are connected via an obtuse angle, i.e. an angle that measures more than 90° but less than 180°. The more straight sections are connected via obtuse angles there between, the more gradual the resulting asymmetrical rudder shape and the bending of the water flow induced by the propeller will be. If the number of straight sections and obtuse angles there between is very large, the shape of the rudder will start to define a curvature.

[0017] According to an even further preferred embodiment, an outer side of at least one of the two flaps of each rudder, and even more preferably an outer side of each of the two flaps of each rudder, that is directed towards the propeller in the reversing state, comprises a curvature that is configured to bend the water flow induced by the propeller. By virtue of the two flaps being pivotable relative to each other, the orientation of these two flaps relative to each other is adjustable to thereby control a deflection of the water flow induced by the propeller. The curvature of the flaps allows the rudder system to provide an adjustable and substantially continuous curvature to thereby gradually deflect the water flow induced by the propeller. In this way, turbulence is prevented, and a high efficiency is obtained.

[0018] In contrast, the rudders of JP H04 358993 A and NL 7014527, that are to be applied as a single rudder of the ship, each comprise two flaps having straight sides directed towards the propeller in the reversing state. By pivoting these straight flaps relative to each other, an angle enclosed by the V-shape of the flaps may be adjusted, but the resulting V-shape will always cause a blocking and resulting turbulence, and will never be able to gradually deflect the water flow induced by the propeller.

[0019] According to an even further preferred embodiment, the curvatures of both flaps of each rudder are configured to form a continuous curve that is configured to gradually bend the water flow induced by the propeller. The continuous curve defines a smooth flow path, preventing turbulence to occur.

[0020] Preferred embodiments are the subject of the dependent claims.

[0021] The invention is further directed to a ship comprising a rudder system according to the invention arranged downstream of a propeller.

[0022] The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, and in particular the aspects and features described in the attached dependent claims, may be made subject of divisional patent applications.

[0023] In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which: Figure 1 is a perspective view of a ship comprising a rudder system according to the invention, and a detailed perspective view of the rudder system being arranged in a straight forward sailing state; Figure 2 is a top view of the rudder system in the straight forward sailing state of Figure 1; Figure 3 is a top view of the rudder system in a forward sailing state while steering said ship; Figure 4 is a top view of the rudder system in a reversing state; and Figure 5 is a top view of the rudder system in a reversing state while steering said ship.

[0024] The ship 1 comprises a hull 2 extending in a longitudinal direction 3. The ship 1 further comprises a propeller 4 that is driveably connected to a drive 5, and a rudder system 6 that is arranged downstream of the propeller 4. The rudder system 6 comprises a pair of rudders 7 arranged on opposite sides relative to a water flow 8 induced by the propeller 4 and configured to deflect the water flow 8 induced by the propeller 4. The water flow 8 may be directed by a nozzle 18.

[0025] Each rudder 7 comprises two flaps 9, 10 that are pivotable relative to each other between a forward sailing state (as shown in Figures 2 and 3) and a reversing state (as shown in Figures 4 and 5). In the reversing state, said flaps 9, 10 are oriented to define a scoop shape of the rudder 7 to deflect and reverse the water flow 8. The forward sailing state is related to forward propulsion of the ship 1, whereas the reversing state is active during forward deceleration, i.e. braking, and during rearward propulsion of said ship 1. The rudder system 6 is configured to deflect the water flow 8 and steer the ship 1 in the forward sailing state, and to deflect and reverse the water flow 8 in the reversing state to cause a forward deceleration or rearward propulsion of said ship 1.

[0026] The two flaps 9,10 of each rudder 7 are both pivotable relative to a common rudder shaft sleeve 11 that rotatably connects the rudder 7, and the two flaps 9, 10 thereof, to the ship 1. A rudder shaft sleeve 11 is a conventional way to arrange a conventional rudder, that has a single rudder shaft, to a ship 1, and therefore the improved rudder system 6 according to the invention may also be arranged in retrofit.

[0027] According to the invention, the rudder shaft sleeve may be a common rudder shaft sleeve 11 that comprises two concentrically arranged shafts 12, 13. These shafts 12, 13 are rotatably received in their common rudder shaft sleeve 11. Shaft 12 may be an outer shaft connected to flap 9 and shaft 13 may be an inner shaft connected to flap 10, or vice versa.

[0028] The two flaps 9, 10 of each rudder 7 are pivotable independently from each other relative to their common rudder shaft sleeve 11. When the common rudder shaft sleeve 11 comprises two concentrically arranged shafts 12, 13 as described above, they may rotate relative to each other inside said common rudder shaft sleeve 11 to define a shape of the rudder 7. In this way, the rudder 7 may be arranged in a scoop shape to deflect and reverse the water flow 8 that is induced by the propeller 4 (Figure 4).

[0029] In the forward sailing state, the two flaps 9, 10 of each rudder 7 extend in substantially opposite directions relative to their common rudder shaft sleeve 11. In this way, the two flaps 9, 10 define a substantially straight shape of the rudder 7, reducing the drag thereof during normal forward sailing (Figures 1 and 2).

[0030] At least one of the two flaps 9, 10 of each rudder 7 may comprise an asymmetrical cross section in top view. In the preferred embodiment shown in the Figures, each of the two flaps 9, 10 of each rudder 7 comprises an asymmetrical cross section in top view (Figures 2-5). The asymmetrical cross section may be defined by a curved outer surface 14 on either one or both of a first side 15 and a second side 16 of the respective flap or flaps 9, 10. More in particular, the flaps 9, 10 may exhibit a wing-shaped profile.

[0031] If the curved outer surfaces 14 of the two flaps 9, 10 of each rudder 7 are arranged on the same side of the rudder 7 relative to the ship 1, they may define a substantially continuously curved outer surface 14 that may guide the water flow 8 at a minimum drag and preventing unwanted turbulence. Such a continuously curved outer surface 14 as defined by the flaps 9 and 10 of a rudder 7 is best seen in the top views of Figures 4 and 5, that both relate to a reversing state. In Figures 4 and 5, the water flow 8 induced by the propeller 4 is deflected and reversed to cause a forward deceleration / braking, or a rearward propulsion of said ship 1. Figure 4 shows a reversing state wherein the ship 1 will drive in a straight line, whereas Figure 5 shows a reversing state wherein the ship 1 will change direction. When driving the ship 1 in a rearward direction, Figure 5 will steer the stern 17 of the ship 1 towards starboard side.

[0032] As the flaps 9, 10 may rotate relative to their common rudder shaft sleeve 11, the curved outer surfaces 14 of the two flaps 9, 10 of each rudder 7 may be rotated relative to the ship 1. These curved outer surfaces 14 that are arranged on the same side of the rudder 7 may be arranged on the first side 15, on the second side 16, or on both sides 15, 16. Dependent on the orientation of the flaps 9, 10 relative to the their common rudder shaft sleeve 11, the first side 15 or the second side 16 may be directed inward or outward relative to the longitudinal direction 3 of the ship 1. In Figures 1 and 2, the curved outer surfaces 14 on the first side 15 are directed inward, i.e. towards the water flow 8 induced by the propeller 4. In the reversing state shown in Figures 4 and 5, the curved outer surfaces 14, 16 on the second side 16 are directed substantially forward relative to the ship 1.

[0033] The ship 1 shown in the Figures comprises a rudder system 6 that comprises a pair of rudders, wherein each rudder 7 of the pair of rudders comprises two flaps 9, 10 that are pivotable relative to each other as described above. The pair of rudders is configured to jointly deflect the water flow 8 induced by the propeller 4 of the ship 1.

[0034] In the preferred embodiment shown in the Figures, the rudders 7 of the pair of rudders are arranged in a mirrored arrangement. The two rudders 7 are pivotable relative to each other and configured to rotate in the same direction relative to the ship 1 to deflect the water flow 8 and steer the ship 1 during forward propulsion thereof, and to rotate in an opposite direction relative to the ship 1 to deflect and reverse the water flow 8 during forward deceleration or rearward propulsion of said ship 1. The flaps 9, that are oriented forward in the forward sailing state of Figures 1 and 2, are directed towards each other in the reversing state of Figure 4.

[0035] In Figure 1, an extendable connector 19, such as a hydraulic cylinder 20, is connected between the outer shafts 12 of two rudders 7, which allow the connection to be made above water level. It is however conceivable that the extendable connector 19 is directly arranged between flaps 9 or flaps 10 of two rudders 7 of the pair of rudders. By adjustment of the length of the extendable connector 19, the flaps 9 or flaps 10 of two rudders 7 may be moved towards or away from each other.

[0036] As best seen in Figure 2, the rudders 7 of the pair of rudders are arranged on opposite sides relative to the water flow 8 induced by the propeller 4. More in particular, one rudder 7 of the pair of rudders is arranged on the port side relative to the water flow 8, and the other rudder 7 of the pair of rudders is arranged on the starboard side relative to the water flow 8.

[0037] The flaps 9, 10 of the rudders 7 may be arranged substantially in line and adjacent the water flow 8 induced by the propeller 4 during straight forward propulsion of said ship 1. More in particular, the rudders 7 may be arranged just outside the water flow 8 during straight forward sailing, so that the water flow 8 is substantially guided between the two rudders 7 of the pair of rudders (Figures 1 and 2).

[0038] During steering, the rudders 7 may be rotated relative to their common rudder shaft sleeve 11, which houses the shafts 12, 30 of both flaps 9, 10 of the respective rudder 7. The water flow 8 is now deflected, and the ship 1 may be steered. During forward sailing of the ship 1, the orientation of the rudders 7 shown in Figure 3 causes the ship 1 to steer towards starboard side.

[0039] The above described embodiment is intended only to illustrate the invention and not to limit in any way the scope of the invention. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims. The scope of the invention is defined solely by the following claims.

Claims

1. Rudder system (6) configured to be arranged downstream of a propeller (4) of a ship (1), the rudder system (6) comprising a pair of rudders (7) that are configured to be arranged on opposite sides relative to a water flow (8) induced by the propeller (4) and configured to jointly deflect the water flow (8) induced by the propeller (4), characterized in that - each rudder (7) of the pair of rudders comprises two flaps (9, 10) that are pivotable relative to each other between a forward sailing state and a reversing state; and - wherein, in the reversing state, said flaps (9, 10) are oriented to define a scoop shape of the rudders (7) that is configured to deflect and reverse the water flow (8).

2. Ship (1) comprising the rudder system (6) according to claim 1 and a propeller (4) that is driveably connected to a drive (5), wherein the rudder system (6) is arranged downstream of the propeller (4) and wherein the pair of rudders (7) is arranged on opposite sides relative to a water flow (8) induced by the propeller (4).

3. Ship according to claim 2, wherein the rudder system (6) is configured to: - deflect the water flow (8) and steer the ship (1) in the forward sailing state; and - deflect and reverse the water flow (8) in the reversing state to cause a forward deceleration or rearward propulsion of said ship (1).

4. Ship according to claim 2 or 3, wherein the two rudders (7) are pivotable relative to each other and configured to rotate: - in the same direction relative to the ship (1) to deflect the water flow (8) and steer the ship (1) during forward propulsion thereof in the forward sailing state; and - in an opposite direction relative to the ship (1) to deflect and reverse the water flow (8) during forward deceleration or rearward propulsion of said ship (1) in the reversing state.

5. Ship according to any of the claims 2 - 4, wherein at least one of the two flaps (9, 10) of each rudder (7) comprises an asymmetrical cross section in top view to define a rudder shape that is configured to bend the water flow (8) induced by the propeller (4) in the reversing state.

6. Ship according to any of the claims 2 - 5, wherein each of the two flaps (9, 10) of each rudder (7) comprises an asymmetrical cross section in top view to define a rudder shape that is configured to bend the water flow (8) induced by the propeller (4) in the reversing state.

7. Ship according to any of the claims 2 - 6, wherein an outer side of at least one of the two flaps (9, 10) of each rudder (7), that is directed towards the propeller (4) in the reversing state, comprises a curvature that is configured to bend the water flow (8) induced by the propeller (4).

8. Ship according to any of the claims 2 - 7, wherein an outer side of each of the two flaps (9, 10) of each rudder (7), that is directed towards the propeller (4) in the reversing state, comprises a curvature that is configured to bend the water flow (8) induced by the propeller (4).

9. Ship according to claim 8, wherein the curvatures of both flaps (9, 10) of each rudder (7) are configured to form a continuous curve that is configured to gradually bend the water flow (8) induced by the propeller (4).

10. Ship according to any of the claims 2 - 9, wherein the two flaps (9, 10) of each rudder (7) are both pivotable relative to a common rudder shaft sleeve (11) that rotatably connects the rudder (7), and the two flaps (9, 10) thereof, to the ship (1).

11. Ship according to any of the claims 2 - 10, wherein the two flaps (9, 10) of each rudder (7) are pivotable independently from each other relative to their common rudder shaft sleeve (11).

12. Ship according to claim 10 or 11, wherein the common rudder shaft sleeve (11) comprises two concentrically arranged shafts (12, 13) that are each connected to a respective one of the two flaps (9, 10).

13. Ship according to any of claims 10 - 12, wherein, in the forward sailing state, the two flaps (9, 10) of each rudder (7) extend in substantially opposite directions relative to their common rudder shaft sleeve (11).

14. Ship according to any of the claims 2 - 13, wherein the flaps (9, 10) of the rudders (7) are arranged substantially in line and adjacent the water flow (8) induced by the propeller (4) during straight forward propulsion of said ship (1).

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