Drive unit with flexible shaft for foil-supported or conventional watercraft

Abstract

Drive unit for a foil-supported watercraft, comprising a drive motor, a flexible shaft and a propeller unit, characterized in that the drive motor is arranged in the support body and is connected to the propeller unit located outside the support body via the flexible shaft.

Description

Technical field:

[0001] The invention relates to a drive unit with a flexible shaft for foil-supported water sports equipment (e.g. eFoils, foil boards), foil boats as well as conventional watercraft such as boats, small watercraft or amphibious platforms. State of the art:

[0002] Well-known foil-based water sports devices like eFoils have a drive motor located below the waterline or integrated directly into the fuselage. This results in bulky underwater structures with increased drag and requires more complex design for sealing and maintenance. Electrical retrofit kits with external modules ("foil assists") are often structurally complex and also hydrodynamically unfavorable. On boats, inboard engines with Z-drives are common, which use a gearbox to position the propeller assembly significantly below the engine. Outboard engines also use a gearbox to achieve the vertical offset between the engine and propeller assembly, which increases size and drag.

[0003] Flexible shafts are known in RC model making and toolmaking, but not for manned watercraft. Flexible shafts are known from the field of hand-operated outboard motors, but these are only designed for low power and speeds and do not offer permanently reliable solutions for sealing, cooling, bearings and coupling. Purpose of the invention:

[0004] The aim is to create a compact, versatile, and easily assembled drive unit that allows for a certain distance and angular offset between the drive motor and propeller unit, while maintaining a slim, streamlined design. The motor should be positioned in a location that is not submerged during operation and therefore does not create any drag.

[0005] Additionally, a retrofittable version is being developed that can be installed with no or only minor modifications. The particular focus is on foil-supported water sports equipment, especially foilboards or eFoils. Solution to the problem:

[0006] The problem is solved by a drive unit in which a drive motor located within the support structure transmits torque via a flexible shaft to a propeller unit situated below the support structure. The volume, and thus the drag, of the underwater structures is reduced by relocating the drive motor out of the flow zone, in contrast to the prior art. Character description Fig. Figure 1 shows a side view of a known prior art eFoil system with a support body (1), a guide housing (2), a fuselage (3), a drive motor (4), a propeller unit (5) arranged thereon, the main airfoil (6) and the stabilizer airfoil (7). Fig. 2 shows that Fig. One known eFoil system in a front view. Fig. Figure 3 shows a first embodiment of the invention with a drive motor (4) with coupling (13) arranged in the support body (1) and a flexible shaft (8) guided through the guide housing (2) in a guide unit (9) with cooling channel (10). The guide housing transitions into the fuselage (3), in which the shaft end (14), the rolling bearings (11) and the sealing unit (12) are located. The shaft end is connected to the propeller unit (5). Fig. Figure 4 shows a second embodiment of the invention with a drive motor (4) arranged in a recess (15) in the upper region of the guide housing (2). The recess also contains the motor control unit (16), battery (17) and communication unit (18). Fig. Figure 5 shows a third embodiment of the invention with a drive motor (4) arranged above the waterline in a protective housing (19). The drive is positioned on a support structure (20) at the stern of the support body (1). Fig. Figure 6 shows a fourth embodiment of the invention with a drive motor (4) arranged in the support body (1) and a guide housing (2) led downwards below the support body (1). Variants

[0007] Variant A ( Fig. 3): In this embodiment for a motor-driven foil surfboard, the drive motor is arranged inside the support body and connected via a coupling to the flexible shaft, which is guided through the guide housing to the fuselage, where the shaft end drives the propeller unit.

[0008] Variant B ( Fig. 4): In this embodiment as a retrofit drive for foil surfboards, the drive motor is located in the upper area of ​​the guide housing within a recess, which also provides installation space for the control and power supply components.

[0009] Variant C ( Fig. 5): This embodiment is designed for outboard mounting on a boat, in which the drive motor is positioned above the waterline and the flexible shaft is guided downwards through the guide housing to the propeller unit.

[0010] Variant D ( Fig.6): In this embodiment as an inboard drive, the drive motor is arranged inside a boat hull, with the guide housing extending outwards below the hull and driving the propeller unit outside the hull. Advantageous embodiments of the invention: fuselage and flow properties:

[0011] The fuselage can be barrel-shaped with a taper towards the propeller unit and optionally feature an S-shaped curved longitudinal contour to create a vertical offset between the propeller unit's axis of rotation and the main airfoil. By positioning the propulsion motor outside the fuselage or above the waterline, the fuselage can be designed to be slimmer and more aerodynamically efficient. Structure of the flexible shaft:

[0012] The flexible shaft preferably consists of twisted or braided steel wires or a comparable torsionally elastic material that allows sufficient torque transmission while maintaining flexibility. It can be constructed in one or more layers. Shaft guidance and bearing:

[0013] The flexible shaft is guided in a tubular guide element, preferably made of PTFE, PEEK, or PA. The guide can be supported by brackets in the guide housing or may include sliding bearing bushings. To minimize friction and wear, the guide can be lubricated with grease. Cooling:

[0014] The flexible shaft can be cooled actively or passively. Active cooling is achieved by targeted water flow around the guide element, for example via integrated cooling channels. Passive cooling can occur through the natural airflow around the guide housing, especially with thermally conductive materials such as aluminum. Storage:

[0015] The rigid shaft end is supported in the fuselage by rolling bearings, optionally in a separate bearing housing. Angular contact ball bearings are preferably used to absorb axial and radial forces. Two single-row angular contact ball bearings can be used in an O or X arrangement. Seal:

[0016] The shaft end is sealed against water and lubricant loss with a sealing unit. This can be designed as a dynamic radial shaft seal or as a combination of static and dynamic seals, for example an O-ring, labyrinth seal or V-ring. Monoblock:

[0017] In a preferred embodiment, the drive unit is designed as a monoblock housing in which the fuselage and guide housing are combined, made of aluminum or fiber-reinforced composites. This improves flow quality and reduces assembly effort. Coupling:

[0018] The flexible shaft is preferably connected to the drive motor via a detachable collet coupling for central fixation. Alternatively, clamping ring, swivel, or universal joint couplings can be used. The coupling is easy to maintain and disassemble. Drive motor:

[0019] The drive motor can be an electric, piston, or turbo motor. Use:

[0020] The drive unit is also suitable for conventional boats, SUPs, skiffs, rowing boats, kayaks, canoes, and amphibious platforms. The same design solution is retained, offering a compact, modular construction and streamlined properties. It can also be used as a retrofit kit.

[0021] The design enables a versatile, low-maintenance and flow-efficient propulsion system that can be integrated into different watercraft in various configurations. legend 1 Supporting body 2 guide housings 3 fuselage 4 Drive motor 5 propeller units 6 Main wings 7 Stabilizer airfoil 8 Flexible shaft 9 Guide element 10 Cooling channel 11 rolling bearings 12 Sealing unit 13 Clutch 14 Shaft end piece 15 bulge 16 Engine control 17 Battery 18 Communication module 19 protective housings 20 Support structure

Claims

[1] Propulsion unit for a foil-supported watercraft, comprising a propulsion motor, a flexible shaft and a propeller unit, characterized by , that the drive motor is located in the carrier body and is connected to the propeller unit located outside the carrier body via the flexible shaft. [2] Drive unit according to claim 1, characterized by that the flexible shaft runs through the curved guide housing. [3] Drive unit according to claim 2, characterized by that components of the clutch or the drive motor protrude into the upper part of the guide housing. [4] Drive unit according to one of claims 1 to 3, characterized by that the flexible shaft is guided in a tubular guide element. [5] Drive unit according to claim 4, characterized by that the guide element is made of a low-friction plastic material, in particular PTFE, PEEK or PA. [6] Drive unit according to one of claims 4 to 5, characterized by that additional sliding bearings are arranged along the shaft. [7] Drive unit according to one of claims 1 to 3, characterized by that the flexible shaft is guided in several ring-shaped guide elements. [8] Drive unit according to one of claims 1 to 3, characterized by that the flexible shaft is guided in plain bearings at several support points. [9] Drive unit according to any one of claims 4 to 8, characterized by that the plastic guides or sliding bearings contain an additional component made of bronze, fiberglass, carbon fiber or graphite. [10] Drive unit according to any one of claims 4 to 9, characterized by that the guide elements are supported in retaining elements in the guide housing. [11] Drive unit according to any one of claims 1 to 10, characterized bythat the flexible shaft runs partially or completely outside the guide housing, along an external guide unit, wherein the guide unit is connected or detachably coupled to the guide housing or fuselage. [12] Drive unit according to any one of claims 1 to 11, characterized by , that a rigid shaft end piece is designed to accommodate the propeller unit and is mounted in the fuselage. [13] Drive unit according to claim 12, characterized by that the storage is carried out by means of at least one bearing, in particular a rolling bearing. [14] Drive unit according to one of claims 12 to 13, characterized by that at least one bearing is designed to absorb axial forces caused by the propeller thrust. [15] Drive unit according to claim 12 or 13, characterized by that the bearing is preferably a single-row or double-row angular contact ball bearing. [16] Drive unit according to one of claims 12 to 14, characterized by that two bearings are arranged axially spaced apart. [17] Drive unit according to claim 16, characterized by , that an angular contact ball bearing is combined with an axially spaced rolling bearing. [18] Drive unit according to any one of claims 12 to 17, characterized by that the bearing arrangement includes a combination of rolling bearings and / or sliding bearings. [19] Drive unit according to any one of claims 12 to 18, characterized by , that at least one bearing is designed to be axially displaceable. [20] Drive unit according to any one of claims 12 to 19, characterized by that two single-row angular contact ball bearings are used in an O or X arrangement. [21] Drive unit according to any one of claims 12 to 20, characterized by that the bearings are mounted in a separate bearing block within the fuselage. [22] Drive unit according to any one of claims 1 to 21, characterized bythat the fuselage has a reduced height and / or width compared to conventional, motor-integrated fuselage designs, because the drive motor is located completely outside the fuselage. [23] Drive unit according to claim 22, characterized by that the fuselage serves exclusively to accommodate the rigid shaft end, the propeller unit and the flexible shaft, as well as to accommodate at least one airfoil, and is shaped in a streamlined manner. [24] Drive unit according to any one of claims 1 to 23, characterized by , that in a preferred embodiment the fuselage is curved in an S-shape in the longitudinal direction to create a height offset between the axis of rotation of the propeller unit and the main airfoil. [25] Drive unit according to any one of claims 1 to 23, characterized by , that in a preferred embodiment the fuselage is barrel-shaped in the longitudinal direction and tapers towards the propeller unit. [26] Drive unit according to any one of claims 1 to 25, characterized by that the fuselage and guide housing are designed as a monoblock housing, with the guide unit, bearing, sealing unit and shaft end piece integrated in a one-piece fuselage guide housing. [27] Drive unit according to claim 26, characterized by that the monoblock is made of aluminum. [28] Drive unit according to claim 26, characterized by that the monoblock is made of fiber composite materials. [29] Drive unit according to claim 26, characterized by that the monoblock design improves flow quality by reducing or avoiding transitions between individual components. [30] Drive unit according to any one of claims 1 to 29, characterized by, that the shaft end is sealed against water ingress and lubricant leakage by a sealing unit, wherein the sealing unit comprises a dynamic seal, in particular a radial shaft seal, and / or a static seal, in particular an O-ring or a labyrinth seal, and wherein the sealing unit is preferably designed as a combination of static and dynamic seal. [31] Drive unit according to claim 30, characterized by that the sealing unit comprises a V-ring with an axially acting sealing lip, wherein the V-ring is preferably arranged in combination with a radial shaft seal. [32] Drive unit according to any one of claims 1 to 31, characterized by, that the flexible shaft is connected to the drive motor via a detachable coupling which enables a positive or non-positive clamping, preferably using a collet chuck for centric clamping; alternatively, a clamping ring, articulated coupling or universal joint with adapter sleeve is provided, and wherein the coupling is designed to be easily detachable for maintenance. [33] Drive unit according to any one of claims 1 to 32, characterized by that the flexible shaft is actively or passively cooled by water. [34] Drive unit according to claim 33, characterized by , that cooling is achieved via a targeted flow around the shaft guide. [35] Drive unit according to claim 34, characterized by that the shaft guide has at least one cooling channel through which water flows. [36] Drive unit according to claim 33 or 34, characterized by, that cooling is passive through natural airflow, especially when using a guide housing made of thermally conductive material such as aluminium, which is surrounded by ambient water during operation. [37] Drive unit according to any one of claims 1 to 36, characterized by The unit is designed as a retrofit kit for unpowered and powered foil-supported watercraft, with the drive motor housed in the upper part of the guide housing, which has a bulge at this point. This bulge provides sufficient space for the drive motor, motor control, communication module, and a battery. The flexible shaft extends from there through the guide housing to the fuselage. [38] Drive unit according to one of the preceding claims, characterized by that the flexible shaft is made of a metallic material, in particular of twisted steel wires. [39] Drive unit according to any one of the preceding claims, characterized by , that the drive unit includes an impeller that runs in a nozzle-like housing. [40] Drive unit according to one of the preceding claims, characterized by that the drive unit includes a folding propeller unit. [41] Drive unit according to one of the preceding claims, characterized by that the drive motor is an electric motor, a piston engine, or a turbo engine. [42] Drive unit according to any one of claims 1 to 41, characterized by that it can be used in a conventional watercraft, in particular a boat, inflatable boat, stand-up paddleboard (SUP), skiff, rowing boat, kayak, canoe, small watercraft or amphibious platform. [43] Drive unit according to claim 42, characterized by that the flexible shaft is guided in a tubular guide element made of a low-friction plastic material, in particular PTFE, PEEK or PA. [44] Drive unit according to one of claims 42 or 43, characterized by that the rigid shaft end piece is supported in at least one rolling bearing, preferably a double-row angular contact ball bearing. [45] Drive unit according to one of claims 42 to 44, characterized by that the shaft is sealed against water ingress and lubricant leakage by a sealing unit. [46] Drive unit according to claim 45, characterized by that the sealing unit includes a V-ring with an axially acting sealing lip. [47] Drive unit according to any one of claims 42 to 46, characterized by that the shaft is connected to the drive motor by means of a detachable coupling, preferably with a collet coupling. [48] ​​Drive unit according to any one of claims 42 to 47, characterized by that the unit is designed as a retrofit kit for unmotorized watercraft. [49] Drive unit according to any one of claims 42 to 48, characterized by that it is suitable for both foil-supported and conventional watercraft, especially boats with inboard or outboard configurations. [50] Drive unit according to any one of claims 42 to 49, characterized by that the flexible shaft is made of a metallic material, in particular of twisted steel wires. [51] Drive unit according to any one of claims 42 to 50, characterized by , that the propulsion motor is mounted above the waterline on a support structure of a conventional watercraft (outboard configuration), with the flexible shaft running through a sealed guide housing below the waterline to the propeller unit. [52] Drive unit according to one of claims 42 to 51, characterized by, that the propulsion motor is arranged inside the hull (inboard configuration), with the flexible shaft being guided through a sealed guide housing to the propeller unit located outside the hull.

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