A hydrofoil vessel

Abstract

The invention involves a hydrofoil vessel (1) comprising - a hull assembly (2), - and a hydrofoil assembly (4) comprising two side struts (401), and a middle strut (402), wherein the side struts and the middle strut extend from the hull assembly (2), wherein the middle strut is located between the side struts, - wherein the hydrofoil assembly (4) comprises two wing portions (412), each wing portion (412) being connected to the middle strut (402) and a respective of the side struts (401) via joints (4121) so as to be individually rotatable in relation to the struts and the other of the wing portions.

Description

[0001] A HYDROFOIL VESSEL

[0002] TECHNICAL FIELD

[0003] The invention relates to a hydrofoil vessel comprising a hydrofoil assembly, and a hull assembly. The invention also relates to a hydrofoil assembly.

[0004] BACKGROUND

[0005] Examples of hydrofoil vessels are found in SE333514 and CN105882915. For hydrofoil vessels, there has traditionally been two types of hydrofoils or wings. One of them is a surface piercing hydrofoil. The other hydrofoil type is a submerged, or immersed, hydrofoil, i.e. a wing that is designed to be fully submerged during a cruising mode of the vessel. An immersed wing may have an adjustable pitch orientation so as to change the angle of attack of the adjustable hydrofoil.

[0006] SUMMARY

[0007] An object of the invention is to provide a solution for an efficient control of a hydrofoil vessel, which is relatively simple to implement. It is also an object of the invention to reduce forces in a control assembly for controlling adjustable hydrofoils.

[0008] The object is achieved with a hydrofoil vessel according to claim 1. Thus, the invention provides a hydrofoil vessel comprising a hull assembly, and a hydrofoil assembly comprising two side struts, and a middle strut, wherein the side struts and the middle strut extend from the hull assembly, wherein the middle strut is located between the side struts,

[0009] - wherein the hydrofoil assembly comprises two wing portions, each wing portion being connected to the middle strut and a respective of the side struts via joints so as to be individually rotatable in relation to the struts and the other of the wing portions. The wing portions may be elongated with a longitudinal direction of the wing portions extending from one of the struts to another of the struts. Thereby, the individual rotatability of each wing portions may be around an axis which is substantially parallel with the longitudinal direction of the wing portion. Preferably, the joints allow the wing portions to be rotatable around an axis which is substantially horizontal when the vessel is not heeling over, and which is substantially transverse to a direction of straight forward travel of the vessel. The rotation of the wing portions may be controlled individually by a suitable actuation system, e.g. including control rods in the side struts. By the rotation of the wing portions, it is possible to control the angle of attack of the wing portions. Thereby, it is possible to control the height of the hull assembly over the water when the vessel is travelling in a hydrofoil mode. By individual control of the wing portions, the roll position, or the degree of heeling, of the vessel can be controlled.

[0010] The wing portions may together form a wing of the hydrofoil vessel. The wing may be a main wing of the vessel, adapted to hold all, or a major portion, of the weight of the vessel. The invention allows for sections of the wing to be rotated individually. This provides a more efficient control compared to a control via flaps on a hydrofoil wing. Also the invention allows for a relatively simple implementation construction-wise compared to that of a control by means of wing flaps.

[0011] The wing portions may be elongated and connected at longitudinal ends thereof to the middle struts and the respective side struts. This offers an advantage compared to an alternative with a single piece wing subjected to torsion to twist the wing for the vessel roll position control. Avoiding such torsion may reduce the forces in a control assembly for controlling the heel of the vessel.

[0012] In some embodiments, each wing portion is connected directly to the middle strut via a joint. In other embodiments, each wing portion is connected indirectly to the middle strut via a joint and an intermediate wing portion.

[0013] In embodiments of the invention, the hydrofoil vessel may be a hydrofoil boat. The vessel may be adapted so that the hull assembly is completely lifted out of the water at hydrofoil mode of the vessel. The hull assembly may comprise a single hull. In some embodiments, the hull vessel may comprise a plurality of connected part-hulls, such as in a multihull assembly.

[0014] For example, the vessel may have a catamaran or a trimaran hull.

[0015] The hull assembly may present, when the vessel is floating at rest, a vertical symmetry plane. The vertical symmetry plane may be imaginary. The external shape of the hull assembly, or at least major features thereof, may be mirrored with reference to the symmetry plane. The wing portions may each extend from a respective one of the side struts towards the symmetry plane.

[0016] The struts may be elongated. The side struts on opposite transverse sides of the symmetry plane. The struts may extend mainly downwards when the vessel is floating at rest. Thereby the side struts may extend mainly within a respective plane which is parallel to the symmetry plane. The middle strut may extend within the symmetry plane. In some embodiments, the side struts may extend partly away from the symmetry plane and partly downwards when the vessel is floating at rest. In other embodiments, the side struts may extend partly away towards the symmetry plane and partly downwards when the vessel is floating at rest. It should be noted that in some embodiments, the hydrofoil assembly may comprise one or more additional struts.

[0017] The wing portions may be elongated. The wing portions may extend from a respective one of the side struts, to the middle strut. The wing portions may be substantially horizontal when the vessel is not heeled over. However, in some embodiments, the wing portions may be in a non-zero angle to horizontal. For example, the wing portions may form a “V”, or an inverted “V”, when viewed along a direction of straight forward travel of the vessel.

[0018] In some embodiments, each wing portion extends inwards from a distal end of the respective side strut. In other embodiments however, each wing portion extends from a position of the respective side strut which is above the distal end of the respective side strut.

[0019] Preferably, each of wing portions extends so as to be terminated at a respective of the side struts. Thereby, a longitudinal end of each wing portion may be at the respective side strut. Thereby, the wing portions may form parts of a wing, the tips of which are directly joined with respective of the side struts. Thereby, the induced drag may be reduced compared to that of a wing with free wing tips. In preferred embodiments, each of wing portions extends so as to be terminated at the middle strut.

[0020] Preferably, each wing portion extends up to the middle strut and / or the respective side strut, wherein the strut to which the wing portion extends presents a substantially flat interface surface facing the respective wing portion, with a normal which is substantially parallel with a rotational axis of the wing portion, and which interface surface extends along at least a majority, i.e. more than 50%, of the extension of the chord to the wing portion at the strut. Thereby, a gap between the strut and the wing portion may be substantially constant at different rotational positions of the wing portion. Thereby, regardless of the rotational position of the wing portion, the gap may be kept small, giving a favourable water flow past the strut to wing portion interface, making a low flow resistance possible.

[0021] Preferably, the respective joint connecting each wing portion to the middle strut is a ball joint. Preferably, the respective joint connecting each wing portion to the respective side strut is a ball joint.

[0022] Preferably, each wing portion is allowed to move in relation to one of struts to which it is connected, substantially in parallel with the rotational axis of the wing portion. In some embodiments, the wing portion comprises a sliding element which extends into a cavity of one of the joints via which the wing portion is connected to the middle strut and the respective of the side struts, wherein the sliding element is allowed to move in the cavity, in relation to the joint, substantially in parallel with the rotational axis of the wing portion. The sliding element may extend substantially in parallel with the rotational axis of the wing portion. The cavity may be an opening in the joint. Thereby, the sliding element could be fixed to the remainder of the wing portion, and extend into the opening. The sliding element could be allowed to move in the opening, so that the wing portion is allowed to move in relation to the strut along the longitudinal direction of the wing portion.

[0023] In other embodiments, a sliding element protrudes from one of the joints via which the wing portion is connected to the middle strut and the respective of the side struts, into a cavity in the wing portion, wherein the sliding element is allowed to move in the cavity, in relation to the wing portion. Thereby, the wing portion is allowed to move in relation to the sliding element substantially in parallel with the rotational axis of the wing portion. In such embodiments, axial movements of an end of the wing portion in relation to the strut, is allowed. For example, where the joint is a ball joint allowing bending of the wing portion so that there is a change of the angle between the wing portion and the strut, the allowance of an axial movement of the end of the wing portion in relation to the strut allows avoidance of tensional forces between the wing portion and the strut. This may reduce the loads on the joint.

[0024] Preferably, for each wing portion, the middle strut, or the respective side strut to which the wing portion is connected, houses at least a portion of a control assembly for controlling the rotational position of the respective wing portion. In some embodiments, each side strut houses the respective control assembly, or a portion thereof. In other embodiments, the middle strut houses control assemblies, or portions thereof, each for controlling the rotational position of the respective wing portion.

[0025] The control assembly may comprise a control rod extending within the strut and in a longitudinal direction of the strut, and being drivingly connected to the respective wing portion. The control rod could be in the form of a pushrod or a pullrod. The control assembly may further comprise a linear actuator arranged to move the control rod along the longitudinal direction of the strut. The linear actuator could be any suitable linear actuator that creates motion in a straight line. The linear actuator could for example be any of a traveling-nut linear actuator, a traveling-screw linear actuator, a hydraulic actuator, a pneumatic actuator, an electro-mechanical actuator, or a linear motor.

[0026] Preferably, the control rod is connected to the wing portion via a lever with a rotation axis between the control rod and a connection of the lever to the wing portion, wherein a distance between the rotational axis of the wing portion and a connection of the control rod to the lever, is shorter than a distance between the rotational axis of the wing portion and the connection of the lever to the wing portion. Thereby, the control rod may be kept close to the rotational axis of the wing portion, and the length of the strut chord may be relatively short, thereby reducing drag.

[0027] An aspect of the invention provides a hydrofoil assembly for a hydrofoil vessel, comprising two struts, wherein the struts are adapted to extend from a hull assembly of the vessel, wherein the hydrofoil assembly comprises a wing element connected to the struts via joints, wherein the wing element extends up to at least one of the struts, wherein the strut to which the wing element extends presents a substantially flat interface surface facing the wing element, with a normal which is substantially parallel with a rotational axis of the wing element, and which interface surface extends along at least a majority of the extension of the chord to the wing element at the strut. In some embodiments, the hydrofoil assembly comprises two side struts, and a middle strut, wherein the middle strut is located between the side struts. Thereby the wing element could be a wing portion connected to the middle strut and one of the side struts via joints so as to be individually rotatable in relation to another wing portion connected to the middle strut and the other side strut. Alternatively, the wing element could be a single piece wing extending between two side struts. Such embodiments could be without any middle strut, and the vessel roll position, or the degree of heeling, could be controlled by twisting the wing.

[0028] The objects are also reached with a hydrofoil assembly according to claim 11.

[0029] Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Below, embodiments of the invention will be described with reference to the drawings, in which:

[0032] - fig. 1 shows a side view of a hydrofoil vessel according to an embodiment of the invention, with a hidden wing portion shown in broken lines in three different angular locations.

[0033] - fig. 2 shows a view of the vessel in fig. 1 from in front of the vessel,

[0034] - fig. 3 shows a cross-section of a part of the vessel as indicated with the arrows III-III in fig. 2,

[0035] - fig. 3b shows a cross-section of the part in fig. 3, as indicated with the arrows Illb-IIIb in fig. 3,

[0036] - fig. 4 shows a perspective and partly sectioned view of a detail of a hydrofoil assembly of the hydrofoil vessel, wherein the section is oriented as indicated by the arrows IV-IV in fig. 3, - fig. 5 shows a side view of a hydrofoil vessel according to an alternative embodiment of the invention,

[0037] - fig. 6 shows a view of the vessel in fig. 5 from in front of the vessel, and

[0038] - fig. 7 shows a cross-section of a part of the vessel as indicated with the arrows VII- VII in fig. 6.

[0039] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0040] Fig. 1 and fig. 2 show a hydrofoil vessel 1. The vessel comprises a hull assembly 2 comprising two connected hulls 201. The hull assembly 2 presents, when the vessel is floating at rest, an imaginary vertical symmetry plane SP, and an imaginary horizontal plane HP coinciding with a waterline of the hull assembly 2. The vessel could be said to be a hydrofoiling catamaran.

[0041] The vessel comprises a hydrofoil assembly 4 described closer below.

[0042] The vessel also comprises two propulsion arrangements, one on each hull. Each propulsion arrangement is provided at a stern of a respective of the hulls 201. Each propulsion arrangement comprises a propeller 501. In this example, each propulsion arrangement comprises an electric motor in a pod 502. The motor is arranged to drive the propeller, which is mounted on the pod. The pod is mounted to the respective hull assembly via a pod carrying strut 503. The motor is arranged to be powered by a power source such as a battery pack. The propulsion arrangements may be controlled so as to steer the vessel.

[0043] In some embodiments, each propulsion arrangement comprises a motor pod comprising two electric motors housed concentrically in the casing, wherein the motors are positioned one after the other in a longitudinal direction of the motor pod. Thereby, the propellers may each be arranged to be driven directly by a respective of the motors, e.g. without a gear arrangement. Thereby, the propellers may be counter-rotating.

[0044] The vessel could be provided with any suitable alternative propulsion arrangement, e.g. comprising an outboard or an inboard engine. More generally, the vessel may comprise an aft wing. The aft wing may be arranged to support, in a hydrofoil driving mode, an aft part of the hull assembly. The aft wing may be mounted to the hull assembly via an aft wing strut. In this embodiment, the vessel further comprises two aft wings 601. The aft wings are mounted to a respective of the hulls 201 via respective aft wing carrying struts 503. Each aft wing carrying strut is also one of the pod carrying struts.

[0045] The hydrofoil assembly 4 comprises two side struts 401, and a middle strut 402. The struts extend from the hull assembly 2. The middle strut is located between the side struts. The side struts extend from the hull assembly 2 on opposite transverse sides of the symmetry plane SP, mainly within a respective plane which is parallel to the symmetry plane. Each side strut extend from a respective of the hulls 201. Each strut 401, 402 has an airfoil shaped crosssection with could be symmetric or non-symmetric.

[0046] The hydrofoil assembly 4 further comprises an adjustable wing 411, comprising two wing portions 412. The adjustable wing 411 may be, as exemplified in fig. 1, in the direction of travel of the vessel 1, located substantially at a center of gravity CG of the vessel. Each wing portion 412 is connected to the middle strut 402 and a respective of the side struts 401 via joints so as to be individually rotatable in relation to the struts and the other of the wing portions. Each of the wing portions 412 extends so as to be terminated at a respective of the side struts 401. Thereby, the wing 411 has an adjustable pitch orientation so as to change the angle of attack of the wing. Further, the wing portions 412 have individually adjustable pitch orientations so as to control the heeling of the vessel. In fig. 1, a hidden wing portion is shown in broken lines in three different angular locations. The individually controllable separate wing portions allow vessel heeling control without wing twisting. This reduces required forces a control system for the heeling control.

[0047] As can be seen in fig. 3, each wing portion extends up to the middle strut and the respective side strut. The struts have feet 4012 which are longer in the direction of travel of the vessel than the extension in the direction of travel of the struts above the feet. The feet have substantially flat interface surfaces 4011 facing the respective wing portion 412. The normal of the interface surfaces are substantially parallel with the rotational axes of the wing portions. The interface surfaces extends along the entire chords to the wing portions at the strut. Thereby, gaps between the struts and the wing portions may be substantially constant at different rotational positions of the wing portions.

[0048] Reference is made also to fig. 3b. The respective joint connecting each wing portion to the respective side strut is a ball joint 4121. Further, the respective joint connecting each wing portion to the middle strut is also a ball joint (not shown). In addition to rotating the wing portion around its rotational axis, the ball joint allows changes of the angle between the strut and the wing portion longitudinal axis.

[0049] In addition, each wing portion 412 comprises a sliding element 4122 extending through an opening in a ball of the ball joint 4121. The extension of a portion of the sliding element, having a cross-sectional shape so as to fit in the opening of the ball, is longer than the extension of the opening. Thereby, the wing portion is allowed to move in relation to the strut substantially in parallel with the longitudinal direction of the wing portion. In other embodiments, the hydrofoil assembly comprises, for each wing portion 412, a sliding element extending from the joint for the connection of the respective wing portion to the middle strut or the respective side strut, into a cavity in the respective wing portion, such that the wing portion is allowed to move in relation to the sliding element substantially in parallel with the longitudinal direction of the wing portion.

[0050] Reference is made to fig. 4. A control system for the wing portions 412 comprises control rods 4015 for controlling the rotational position of the wing portions 412. Each side strut 401 houses a respective of the control rods for control of the respective wing portion 412. Each control rod is arranged to be driven by a linear actuator 4016, such as a hydraulic actuator or a traveling-screw linear actuator. Each control rod is connected to the respective wing portion via a respective lever 4013. The lever is located in the foot 4012 of the strut. The lever has a rotation axis 4018 between the control rod and a connection of the lever to the wing portion. Thereby, a distance between the rotational axis 4123 of the wing portion 412 and a connection 4014 of the control rod to the lever 4013, is shorter than a distance between the rotational axis 4123 of the wing portion 412 and the connection 4017 of the lever 4013 to the wing portion 412. As illustrated in fig. 4, the chord of the wing portion 412 is longer at the strut 401 than further away from the strut. Thereby a long moment arm is provided for the wing portion rotation, reducing control rod forces, while the wing portion is kept slender, which is hydrodynamically advantageous. A position sensor (not shown) is provided at a bearing for the wing portion rotation for feedback to an electronic controller of the control system for the wing portion control, on the rotational position of the wing portion. This enables trouble shooting and preventative maintenance of the control system.

[0051] Fig. 5 - fig. 6 show a hydrofoil vessel 1 according to an alternative embodiment of the invention, with major differences to the embodiment in fig. 1 - fig. 3 as follows. The vessel comprises a hull assembly 2 comprising a single hull. The vessel comprises a hydrofoil assembly 4 described closer below.

[0052] The vessel also comprises a single propulsion arrangement, provided at a stern of the hull. The motor of the power arrangement is arranged to be powered by a power source such as a battery pack 504. An aft wings 601 is mounted to the power arrangement.

[0053] The hydrofoil assembly 4 comprises two side struts 401, and a middle strut 402. The struts extend from the hull assembly 2. The hydrofoil assembly 4 further comprises a wing 411, comprising a middle wing section 413 which is fixed to the middle strut 402. Each wing portions 412 is connected to the middle strut 402 via a respective joint and via the middle wing section 413. Further, each wing portion 412 is connected to a respective of the side struts 401 via joints so as to be individually rotatable in relation to the struts, the middle wing section 413, and the other of the wing portions. Each of the wing portions 411 extends past the respective of the side struts 401. Thereby, the wing 411 has free tip ends located outside the side struts.

[0054] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

CLAIMS1. A hydrofoil vessel (1) comprising a hull assembly (2), and a hydrofoil assembly (4) comprising two side struts (401), and a middle strut (402), wherein the side struts and the middle strut extend from the hull assembly (2), wherein the middle strut is located between the side struts, characterized in that the hydrofoil assembly (4) comprises two wing portions (412), each wing portion (412) being connected to the middle strut (402) and a respective of the side struts (401) via joints (4121) so as to be individually rotatable in relation to the struts and the other of the wing portions.

2. A hydrofoil vessel according to claim 1, wherein each of the wing portions (412) extends so as to be terminated at a respective of the side struts (401).

3. A hydrofoil vessel according to any one of the preceding claims, wherein each wing portion (412) extends up to the middle strut (402) and / or the respective side strut (401), wherein the strut to which the wing portion extends presents a substantially flat interface surface (4011) facing the respective wing portion, with a normal which is substantially parallel with a rotational axis of the wing portion, and which interface surface extends along at least a majority of the extension of the chord to the wing portion at the strut.

4. A hydrofoil vessel according to any one of the preceding claims, wherein the respective joint (4121) connecting each wing portion (412) to the middle strut (402) is a ball joint.

5. A hydrofoil vessel according to any one of the preceding claims, wherein each wing portion (412) is allowed to move in relation to one of struts to which it is connected, substantially in parallel with the rotational axis of the wing portion.

6. A hydrofoil vessel according to any one of the preceding claims, wherein, for each wing portion (412), the middle strut (402), or the respective side strut (401) to whichthe wing portion is connected, houses at least a portion of a control assembly (4013, 4015, 4016) for controlling the rotational position of the wing portion.

7. A hydrofoil vessel according to claim 6, wherein the control assembly comprises a control rod (4015) extending within the strut and in a longitudinal direction of the strut, and being drivingly connected to the wing portion (412).

8. A hydrofoil vessel according to claim 7, wherein the control assembly further comprises a linear actuator (4016) arranged to move the control rod (4015) along the longitudinal direction of the strut.

9. A hydrofoil vessel according to any one of claims 7-8, wherein the control rod (4015) is connected to the wing portion (412) via a lever (4013) with a rotation axis (4018) between the control rod (4015) and a connection (4017) of the lever to the wing portion, wherein a distance between the rotational axis (4123) of the wing portion and a connection (4014) of the control rod to the lever, is shorter than a distance between the rotational axis (4123) of the wing portion and the connection (4017) of the lever to the wing portion.

10. A hydrofoil assembly (4) for a hydrofoil vessel, comprising two struts (401, 402), wherein the struts are adapted to extend from a hull assembly (2) of the vessel, wherein the hydrofoil assembly (4) comprises a wing element (412) connected to the struts via joints (4121), wherein the wing element extends up to at least one of the struts, wherein the strut to which the wing element extends presents a substantially flat interface surface (4011) facing the wing element, with a normal which is substantially parallel with a rotational axis of the wing element, and which interface surface extends along at least a majority of the extension of the chord to the wing element at the strut.

11. A hydrofoil assembly (4) for a hydrofoil vessel according to any one of claims 1-9.

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