Fin Stabilizer, a Vibration Damping Element and a Watercraft

This application claims priority to German patent application no. 102024205106.3 filed on Jun. 3, 2024, the contents of which are fully incorporated herein by reference.

The invention relates to watercraft, and more particularly to fin stabilizers for watercraft.

Fin stabilizers are used for roll stabilization of a watercraft when the watercraft is at anchor or for course correction of the watercraft when underway. One type of known fin stabilizer is a pivoting stabilizer, which includes a stabilizer fin which is retracted into a fin box in an idle position. Another type of fin stabilizer is a fixed stabilizer in which the stabilizer fin is always located outside of the hull of the watercraft. With both types of fin stabilizers, the stabilizer fin can perform up and down movements about a longitudinal axis when located in a working position.

Fin stabilizers, especially those on relatively large watercraft, are typically driven electro-hydraulically. Fin stabilizers that are driven by purely electric means are less common and, without exception, operate with mechanical transmissions. By means of mechanical transmissions, the high speed of the electric motor is reduced to the low output speed for driving the fin stabilizers, and high output-side torques required to drive the fin stabilizers can be achieved.

In addition to the drive actuator itself, the mechanical transmission also introduces vibrations into the ship's hull wall, and these vibrations may cause stress on the ship's structure. Also, depending on the sector of the shipping industry, e.g. in yacht construction, there are high demands with respect to reduction of the structure-borne noise levels caused by those components of ship stabilizers during rotary motion.

Moreover, the stabilizer fin exerts forces on the other components of the stabilizer. Among these forces are bending moments, transverse forces, normal forces and torsional forces. However, components such as transmissions require high precision in certain aspects, such as for example, alignment, component manufacture, installation tolerances and protection from such external loads.

An object of the present invention is to provide a fin stabilizer which at least reduces the transmission of vibration from the fin stabilizer into a ship's structure and furthermore at least reduces the introduction of loads from the stabilizer fin into components operatively connected to the stabilizer fin. It is furthermore an object of the present invention to provide a vibration damping element for a fin stabilizer of this kind, and a watercraft having an at least reduced structure-borne noise level in the region of its fin stabilizer.

A fin stabilizer according to the present invention is provided for roll stabilization of a watercraft and includes a stabilizer fin which is mounted so as to be rotatable about its longitudinal axis. To rotate the stabilizer fin or change an angle of attack of the stabilizer fin, the fin stabilizer has a drive unit. The drive unit has a mounting portion, which can be fastened in a manner secure against rotation to a hull wall via a corresponding attachment portion. According to the invention, at least one vibration damping element is arranged between the drive-side mounting portion and the hull-side attachment portion, such that the mounting portion is at a physical distance from the attachment portion, i.e., the mounting portion is spaced from the attachment portion. Thus, there is no direct physical contact between the mounting portion and the attachment portion, but only indirect contact via the at least one vibration damping element.

A vibration damping clement according to the present invention for a fin stabilizer of this kind has an outer part for attachment to a drive-side mounting portion and has an inner part for attachment to a ship's hull-side attachment portion, wherein at least one of the parts has vibration-damping properties.

A watercraft according to the present invention is fitted with a fin stabilizer as disclosed herein.

By means of the at least one vibration damping element, the mounting portion is decoupled from the attachment portion, ensuring that the transmission of structure-borne noise from the drive unit (i.e., the actuator) into the structure of the ship is either reduced or substantially prevented. Moreover, the at least one vibration damping element makes it possible to reduce loads on components operatively connected to the stabilizer fin.

In one preferred embodiment, a multiplicity or plurality of vibration damping elements is provided. By means of this measure, redundancy is created, and therefore, in the unlikely event of a fault or failure of one of the vibration damping elements, the performance and safety of the fin stabilizer is ensured. For example, the vibration elements are distributed uniformly over the circumference of the mounting portion and of the attachment portion.

In particular, each vibration damping element can have an outer part, which is releasably connected to the mounting portion, and an inner apart, which is releasably connected to the attachment portion. This enables each part to be adjusted in an optimum manner in respect to its material and/or shape.

In one preferred embodiment, the respective outer part consists of a harder material than the respective inner part. For example, the outer part can be a metal ring, which fits around the inner part, which is elastomer-based, for example, and is inserted firmly therein.

As a preferred option, each vibration damping element is positioned in a receptacle of the mounting portion. This enables each vibration element to be mounted on and attached to the mounting portion in an optimum manner since collision or contact with adjacent vibration damping elements is prevented. The receptacles are, for example, apertures or holes, which can be introduced into the fastening flange in a manner that is simple in terms of manufacturing technology. The alignment of the mounting portion with respect to the attachment portion can be simplified if the attachment portion has a corresponding number and alignment of counter-receptacles.

Exchanging vibration damping elements, e.g. in the context of maintenance or inspection, can be simplified if these can be removed individually without removing the mounting portion of the drive unit.

In particular, the outer parts of the vibration damping elements and the apertures can have a rotationally asymmetrical outer and inner contour respectively, ensuring that the vibration damping elements can only be positioned in, or alternatively removed from, the apertures by means of a rotating-sliding movement. For this purpose, the outer parts can have an oval outer contour or a diamond-shaped outer contour, for example. The apertures in the mounting portion then have a corresponding oval or diamond-shaped inner contour, such that, after the insertion and rotation of the vibration damping elements, their outer parts are partially in overlap with the mounting portion. In the region of the overlap, the vibration damping elements are then attached to the mounting portion.

shows a partial region of a fin stabilizeraccording to the present invention, shown in longitudinal section. The fin stabilizeris used for the roll stabilization of a watercraft, such as a freighter or a yacht, both underway or at anchor.

The fin stabilizerincludes a stabilizer finwith a fin shaftand a drive unit. In addition, the fin stabilizerhas a coupling (not shown), a fixing device for securing the stabilizer finat an angle of attack and an open-loop and closed-loop control device (not shown).

The stabilizer finis connected positively, non-positively and/or frictionally to a driven shaft of the drive unitby the fin shaftand the coupling. The coupling is, for example, a clamp coupling, a steel multi-plate clutch, etc., and the driven shaft in the example shown here is a transmission output shaft of a transmissionof the drive unit. A drive of the drive unitcan be of hydraulic or purely electric design, for example, being designed as an electric motor. The transmissionis interposed in the drive. However, it is also conceivable to dispense entirely with the transmission, for example if the electric motor is embodied as a high-torque synchronous motor with a large number of poles.

The fin shaftextends through a holder tubeand is mounted rotatably about a longitudinal axis through the tubeby means of bearing assemblies (not shown). For example, the bearing assembly may include a rolling bearing assembly and a water-tight sliding seal assembly. The rolling bearing assembly is, for example, a two-row self-aligning barrel roller bearing and is arranged remote from the water, namely proximal to the coupling. The sliding seal is arranged close to the water, namely remote from the coupling. As such, the seal prevents penetration of seawater into an annular space (not indicated) between the holder tubeand the fin shaftand thus protects the rolling bearing from the water.

The holder tubeitself is guided axially by a carrier tube, which extends through a section of an external skin or a hull wallon the water side and is firmly connected in a manner secure against rotation, preferably welded, to the hull wall. With its end within the hull, the carrier tubeforms a flange, to which the holder tubeis attached, e.g. screwed, by means of its outer shoulder.

To attach the drive unit, in this case the transmission, to the holder tubeso as to be mounted in a manner secure against rotation, the holder tubehas an attachment flange or attachment portionat its end within the hull. The transmissionhas a corresponding mounting flange or mounting portion. Attachment of the transmissionto the holder tubeis accomplished by means of a multiplicity or plurality of two-part screwed joints.

According to the present invention, the mounting portionand the attachment portionare not in direct physical contact but are instead in contact by means of a plurality of vibration damping elementsarranged between the mounting portionand the attachment portionin the manner of “spacers”. Preferably, each screwed joint is assigned or includes one vibration damping element.

Exemplary vibration damping elements, including the screwed joints, are shown in.

The vibration damping elementsare preferably of identical design or identically formed. The vibration damping elementseach have an outer partwhich rests from a rear against the mounting flange(i.e., the first screwed joint part), and an inner part, which extends axially through apertures(preferably each formed as circular hole) in the mounting flangeand is penetrated by an axial fastening screw. Each fastening screwengages in a corresponding internally threaded holein the attachment flange(i.e., the second screwed joint part). In the screwed state, each vibration damping elementis clamped by means of the threaded engagement between the hull-side attachment flangeand a respective screw head, with the result that the end of the respective inner partof the vibration damping elementsis pressed against the attachment portion. For uniform introduction of a screwing force, washers (not shown) are preferably arranged under the screw heads, the washers completely covering the ends of the inner parts.

In the exemplary embodiment shown in, the respective outer partis an annular flange, which rests against the rear of the mounting flangeby means of a multiplicity or plurality of screws (none shown). The outer partpreferably consists of (i.e., is formed of) a relatively harder material than a material of the inner part. Examples of such relatively harder materials of the outer partare metals or metal alloys and the inner partmay be formed of an elastomeric material, as described below.

When viewed in a direction from the front to the rear (from the mounting portionin the direction of the attachment flange), the respective inner parthas a conically widening or tapering shape. Each outer partis arranged on a radially widest location of the inner part. The outer partseach extend around and are integrally connected with the inner part, for example, by being adhesively bonded to or cast or molded to the inner part. Each inner partconsists of, or is formed of, a material that is relatively softer or less hard than the material of each outer part. The material of the inner partprovides a damping effect and may be, for example, a rubber-type material or an elastomer such as natural or synthetic rubber.

In order to enable the vibration damping elementsto be screwed to the mounting flange, the respective outer part(annular flange) thereof has an outside diameter which is larger than an inside diameter of the circular apertures. For the removal of individual vibration damping elementsof the exemplary embodiment shown in, e.g. in order to conduct an inspection, the entire mounting flange, and thus the entire transmission, must be removed. That is, in order to remove one vibration damping element, all the vibration damping elementshave to be removed.

In another exemplary embodiment shown in, the vibration damping elementsare removed and mounted individually from the front with the mounting portionmounted on the transmission.

In this case, aperturesin the mounting portionand outer partsof the vibration damping elementsdo not have a rotationally symmetrical contour as with the exemplary embodiment according to, but instead have asymmetrical contours such that the outer partcan only be passed or inserted axially through each aperturein a specific first alignment with respect thereto, and can only be placed or positioned into rear-side contact with the mounting flangein a specific second alignment, which is different from the first alignment. In other words, after each outer partpasses through an aperture, the outer vibration damping elementmust be rotated about its longitudinal axis in order to achieve the overlap between the outer partand the mounting portionto enable screw fastening in the region of overlapping body portions. In the depicted exemplary embodiment, the apertureseach have an oval inner contour and the outer partseach have a corresponding oval outer contour. Illustrative alternative contours are diamond-like contours.

A disclosure is made herein of a fin stabilizer for roll stabilization of a watercraft, the drive unit of which is connected in a vibration-damping manner to a ship's structure, a vibration damping element and a watercraft.

Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention.

Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. The invention is not restricted to the above-described embodiments, and may be varied within the scope of the following claims.