Field of the invention

The present invention relates to an adjustable thrust generating foil system for use on a vessel in water.

Background of the invention.

Some vessels do part of the time sail 0 to 5 knots in the open sea, or use propulsion system towards wind, sea and current, to maintain their position. It will then be needed propulsion power in all directions, to maneuver the vessel safely at all times. Examples of vessels where this operation mode is used is standby vessels around offshore oil platforms or offshore wind farms.

One way to reduce fuel consumption when standby on the offshore field is to use the wave energy to maneuver the vessel.

Objects of the present invention

The invention has one or more of the following objects:

- providing a device for utilizing the vertical movement of a vessel relative to a body of water to produce thrust in the horizontal direction.

- proving a foil system that can produce forward or backward thrust for a vessel as the vessel moves in the water

- providing hydrofoil profile in water, attached to a vessel hull, which can give the vessel thrust either forward or backwards or no thrust

- providing a system that can lift the foil system out of water

- provide a system that can be used as shock absorber for the foil in rough weather

- providing a system where the foil on starboard of the vessel can be operated independently from the foil on port side Summary of the invention

The invention is in one aspect an adjustable thrust generating foil system for use on a vessel in water. The foil system comprises:

- a horizontal foil,

- a support structure for connecting the foil system to the vessel, and

- a suspension system for connecting the foil to the support structure.

The suspension system comprises:

- a first piston cylinder assembly connected to the support structure in a first end, and to the foil in a second end,

- a second piston cylinder assembly, connected to the support structure in a first end, and to the foil in a second end, and

- a rigid rod connected to the support structure in a first end, and to the foil in a second end.

The suspension system is arranged to allow the foil to be angled relative to the support structure by letting the piston cylinder assemblies extend and retract as the foil moves in a body of water. A control system is configured to lock and release the extension and retraction of the piston cylinder assemblies to keep the foil in a desired angle for converting movement in a vertical direction into thrust in a horizontal direction.

The first and the second ends of the first and the second piston cylinder assemblies seen from an end of the foil can constitutes the four corners of a full quadrilateral, and wherein the two piston cylinder assemblies makes up two of the four sides of the full quadrilateral.

The foil system can be arranged in connection with the bow of the vessel.

The foil system can comprise two or more foil sections that can each be individually manipulated by its own one or more suspension system.

Each foil section can be equipped with two suspension systems.

The foil system can be attached to the vessel hull by a structure that is turnable around a vertical axis. The first and the second piston cylinder assembly can be able extend or retract if exposed to forces above a predefined threshold for the purpose of dampening impacts to the system.

The foil system can be lifted out of the water by pivoting the foil system around a tilt up hinge.

The first and second piston cylinder assemblies comprises biasing members arranged to bias the first and second piston cylinder assemblies into a half way extended position.

The rigid rod can be connected to the foil at the second end of the first piston cylinder assembly and the rigid rod can be connected to the support structure at the first end of the second piston cylinder assembly.

The rigid rod can be connected to the foil at the second end of the second piston cylinder assembly and the rigid rod can be connected to the support structure at the first end of the first piston cylinder assembly.

The connection of the rigid rod to the foil and to the support structure at the ends of the piston cylinder assemblies should be understood as at least close to the ends if not exactly at the ends.

Description of the diagrams

Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein:

Fig. 1 shows the foil system mounted on the bow of a vessel, seen from above.

Fig. 2 shows the foil system mounted on the bow of a vessel, seen from the side.

Fig. 3 shows the foil system mounted on the bow of a vessel, seen from the fore.

Fig. 4 shows the foil system mounted on the bow of a vessel and indicates that the starboard foil section can give thrust forward, and port foil section can give thrust backwards, or opposite.

Fig. 5 shows the foil system turned, a feature that can be used for directing the foil towards the waves.

Fig. 6 shows a section (from the side or with other words from an end of the foil) of the foil and the arrangement for linking the foil to the supporting structure.

Fig. 7 (7.1 - 7.4) shows in sequence the orientation of the foil as the foil move relative to the water. The sequence showed in Fig. 7 is the sequence for generating forward thrust (to the left in the figures). Arrows indicating the direction of push from the water.

Fig. 8 (8.1 - 8.4) shows in sequence the orientation of the foil as the foil move relative to the water. The sequence showed in Fig. 8 is the sequence for generating thrust backwards (to the right in the figures). Arrows indicating the direction of push from the water.

Description of preferred embodiments of the invention

In the following description the term foil 11 is used to describe the structure with reference number 11 in the drawings. Wavefoil, hydrofoil or wing could also be used as a term to describe this structure.

In some of the figures there are arrows to indicate the direction of thrust (arrow number 4) and in which direction the water 3 is pushing on the foil 11 (arrow number 5).

Fig. 1 shows the foil system 10 seen from above. The foil system 10 comprises an elongated foil 11 submerged in water 3 and supported by a support structure 12 connected to the bow 2 of a vessel 1 . A linear actuator 16 is arranged to swing the foil system 10 around a vertical axis relative to the vessel 1. The linear actuator 16 can be an electrical actuator such as a screw or a piston cylinder assembly either hydraulically actuated or pneumatically actuated. The feature of turning or swinging the foil system 10 can be used to turn the foil system 10 up against waves to get a better angel of attach and/or to turn the vessel 1.

In Fig. 2 the foil system 10 is seen from the side. The whole foil system 10 can be lifted out of the water by tilting the foil system 10 up around the tilt up hinge 17. There is also a vertical hinge 19 for turning/swinging the foil system 10 and an additional anchoring point or fastening point 18 to secure the foil system 10 to the bow 2. The support structure 12 is also visible in Fig. 2. The fastening point 18 can be a hinged connection.

In Fig. 3 the foil system is seen from fore. The support structure 12 can have a wide variety of designs but one preferred design is seen in Fig. 3. In Fig. 3 one can see a foil 11 that is divided into a starboard and a port foil section 11.3, 11.4. Each connected to the support structure by two suspension systems 20.

In Fig. 4 the foil system 10 is again seen from above, now arrows 4 are indicating the direction of the thrust generated by the foil 11. As mentioned, the foil 11 can be divided into sections for instance a starboard section 11.1 and a port section 11.2 as seen in Fig. 3 and 4. The foil sections 11.1 , 11 .2 can then be manipulated individually to create thrust with opposite horizontal force components. This can be utilized to maneuver the vessel 1. In Fig. 5 the feature of turning or swinging the foil system 10 around the vertical axis can be seen. The foil system 10 is in Fig. 5 turned towards the waves and/or used to turn the vessel 1 to port.

Fig. 6 shows the foil 11 and the suspension system 20 seen from the side. The suspension system 20 connects the foil 11 to the support structure 12 and allows the foil 11 to move and to be angled within certain boundaries. The suspension system 20 also enables the foil, to be locked in certain positions and the suspension system can also have a dampening effect.

The suspension system 20 comprises a first piston cylinder arrangement 13, a second piston cylinder arrangement 14 and a rigid rod 15. The piston cylinder arrangements can be hydraulic cylinders with a piston and a piston rod. The piston cylinder assemblies 13, 14 can be controlled by a control system that can lock the piston cylinder assembly, so they are prevented from being retracted or extended. This can be done by closing one or more valves preventing fluid from entering or escaping the cylinder hence locking any movement of the piston inside the cylinder.

Even though a hydraulic piston cylinder assembly is preferred other types of actuators can be used. Pneumatic actuators or electrical actuators with pitch rack, screws or linear motors can be used.

During operation as the foil 11 is moved up and down relative to the water 3 the foil 11 will either push or pull on the piston cylinder assemblies 13, 14. By locking one or both of the piston cylinder assemblies 13, 14 in various positions (extended or retracted position or in between) as the foil 11 moved in the water the foil 11 will generate a horizontal force component that can be used to move or maneuverer the vessel 1 .

Since it is the vertical relative movement between the foil 11 and the water 3 that pushes and pulls on the foil 11 and position it, there is no need to add external energy (at least very limited need for external energy). Hence the foil system 10 is very energy efficient and can generate propulsion hardly without any use of external energy. The first piston cylinder assembly 13 is connected to the support structure 12 in a first end 13.1 , and to the foil 11 in a second end 13.2. The second piston cylinder assembly 14 is connected to the support structure 12 in a first end 14.1 , and to the foil 11 in a second end 14.2. The second end 13.2 of the first piston cylinder assembly 13 is connected closer to a leading edge 11.1 of the foil 11 than the second end 14.2 of the second piston cylinder assembly 14. The rigid rod 15 is connected to the support structure in a first end 15.1 , and to the foil 11 in a second end 15.2.

Fig. 6 shows a preferred arrangement of the suspension system 20 and the position of the connection points (13.1 , 13.2, 14.1 , 14.2, 15.1 and 15.2).

The connection point 15.1 should preferably be at or between 13.1 and 14.1 on an imagined horizontal axis (it can be above or below i.e. at other points on an imagined vertical axis) in the plane seen in Fig. 6. Likewise, should the connection point 15.2 be at or in between the connection points 11.1 and 11 .2 on an imagined horizontal axis.

The four connection points 13.1 , 13.2, 14.1 and 14.2 will seen from the side as in Fig. 6 constitute the four corners of a full quadrilateral.

The foil 11 does not need to have the exact shape as seen in the figures. For instance, can the shape of the trailing edge 11.2 be more like the leading edge 11.1. Such a foil will be better suited to create thrust to both push the vessel backwards and pulling the vessel 11 forward.

As mentioned, the foil 11 can be quite long and divided into several sections such as a starboard foil section 11.3 and a port foil section 11.4, as seen in Fig. 3. Each section 11.3, 11 ,4 can be operated individually by its own suspension system 20. Each foil section 11.3, 11 .4 can have one or more suspension systems 20.

Fig. 7.1 - 7.4 shows how the foil can give thrust forward when moving up and down in water.

• Fig. 7.1 : Water pressure (indicated by the arrows 5) is acting on the bottom of the foil (foil is pushed down in the water). The first piston cylinder assembly 13 is rigid. The second piston cylinder assembly 14 will be pushed into a retracted position by the force of the water. This will cause the angle of attach of the foil to change to the next position, as shown in Fig. 7.2.

• Fig. 7.2: Water pressure is still acting on the bottom of the foil 11 . The first and the second piston cylinder assembly 13, 14 is now rigid. The water pressure is still acting on the foil 11 from below the foil 11 . Because of the new angle of attach of the foil 11 , the foil will cause a forward thrust force (and also a damping force on the foil system 10).

• Fig. 7.3: Water pressure is acting on the top of the foil (foil is now pulled upwards in the water), and the first piston cylinder assembly 13 is rigid, and the second piston cylinder assembly 14 will be extended into an extended position by the water force. This will cause the angle of attach of the foil 11 to move to its next position, as shown in Fig. 7.4.

• Fig. 7.4: Water pressure is still acting on the top of the foil 11 , and the first piston cylinder assembly 13 is rigid. Because of the new angle of attach of the foil 11 the foil will cause a forward thrust force (and also a damping force on the foil system 10).

Fig. 8.1 - 8.4 shows how the foil 11 can give thrust backwards when moving up and down in water.

• Fig. 8.1 : Water pressure (indicated by the arrows 5) is acting on the bottom of the foil 11 (foil pushed down in the water). The second piston cylinder assembly 14 is rigid, and the first piston cylinder assembly 13 will be pushed into a retracted position by the force of the water. This will cause the angle of attach for the foil to move to its next position, as shown in Fig. 8.2.

• Fig. 8.2: Water pressure is still acting on the bottom of the foil 11 , and the first and the second piston cylinder assembly 13, 14 is now rigid. Because of the new angle of attach of the foil the foil will cause a backwards thrust force (and also a damping force on the foil system 10).

• Fig. 8.3: Water pressure is acting on the top of the foil 11 (foil is now pulled upwards in the water). The second piston cylinder assembly 14 is rigid, and the first piston cylinder assembly 13 will be extended to an extended position by the force of the water. This will cause the angle of attach of the foil 11 to move to its next position, as shown in Fig. 8.4.

• Fig. 8.4: Water pressure is still acting on the top of the foil 11 . The first and the second piston cylinder assembly 13, 14 is now rigid. Because of the new angle of attach of the foil 11 the foil will cause a backwards thrust force (and also a damping force on the foil system 10).

The system 10 can further comprise biasing members arranged to bias the first and the second piston cylinder assembly 13, 14 into a half way extended position i.e. the piston of the piston cylinder assemblies is in the middle of the cylinder (in the longitudinal direction). Half way should not be understood as exactly half way since that in practice will be hard to achieve. The biasing member can for instance be one or two springs integrated in the piston cylinder assemblies 13, 14. The strength of biasing force should be so that the piston cylinder assemblies is allowed to extend and retract as a result of the movement of the foil 11 in water 3.

This biasing member can be hydraulic or gas spring or a conventional mechanical spring.

The biasing members are not included in the drawings. Simulations has showed that including such biasing members in the piston cylinder assemblies 13, 14 will increase the efficiency of the system 10.

The system as here described will enable a vessel 1 to be maneuvered and to propel the vessel 1 (estimated between 1-5 knots dependent on conditions) by use of the foil system 10. Maneuvering the vessel 1 can be done by turning the foil system 10 as seen in Fig. 5 or by operating the two or more foil sections 11.3, 11.4 individually as seen in Fig. 4 where it is forcing the vessel to turn starboard.

In one aspect the invention is an adjustable thrust generating foil system 10 for use on a vessel 1 in water 3, wherein the foil system 10 comprises:

- a horizontal foil 11 ,

- a support structure 12 for connecting the foil system to the vessel 1 ,

- a suspension system 20 for connecting the foil 11 to the support structure 12, wherein the support structure comprises: - a first piston cylinder assembly 13 connected to the support structure 12 in a first end 13.1 , and to the foil 11 in a second end 13.2,

- a second piston cylinder assembly 14, connected to the support structure 12 in a first end 14.1 , and to the foil 11 in a second end 14.2, and

- a rigid rod 15 connected to the support structure in a first end 15.1 , and to the foil 11 in a second end 15.2, wherein the first ends 14.1 , 14.2 and the second ends 13.2, 14.2 of the first and the second piston cylinder assemblies 13, 14 seen form an end 11.5, 11.6 of the foil constitutes the four corners of a full quadrilateral, and wherein the two piston cylinder assemblies 13, 14 makes up two of the four sides of the full quadrilateral, and wherein the two piston cylinder assemblies 13, 14 is arranged to be retracted and extended as the foil 11 is moved in a body of water 3, and wherein a control system is configured to block the extension and retraction of the piston cylinder assembly 13, 14 when the foil 11 is in a desired angle for converting movement in a vertical direction into thrust in a horizontal direction.

The invention relates to an adjustable thrust generating foil system 10 for use on a vessel 1 in water 3. The foil system comprises:

- a horizontal foil 11 ,

- a support structure 12 for connecting the foil 11 system 10 to the vessel 1 ,

- a suspension system 20 for connecting the foil 11 to the support structure 12, wherein the suspension system 20 is configured to allow the foil 11 to be angled relative to the support structure 12 as the foil 11 moves in a body of water 3, and wherein a control system is arranged to lock the position of the foil 11 when the foil 11 is in a desired angle for converting movement in a vertical direction into thrust in a horizontal direction.

The suspension system 20 can comprise:

- a first piston cylinder assembly 13 connected to the support structure 12 in a first end 13.1 , and to the foil 11 in a second end 13.2,

- a second piston cylinder assembly 14, connected to the support structure 12 in a first end 14.1 , and to the foil 11 in a second end 14.2, and

- a rigid rod 15 connected to the support structure 12 in a first end 15.1 , and to the foil 11 in a second end 15.2.