WO2022174289A1

WO2022174289A1 - Propeller for powered watercraft

Info

Publication number: WO2022174289A1
Application number: PCT/AU2022/050107
Authority: WO
Inventors: Lars Milde; Ken MACKEN
Original assignee: Fliteboard Pty Ltd
Current assignee: Fliteboard Pty Ltd
Priority date: 2021-02-19
Filing date: 2022-02-17
Publication date: 2022-08-25
Anticipated expiration: 2023-08-19

Abstract

An electric powered watercraft, comprising a hull, a battery, a controller, and a motor configured to turn a drive shaft that is operatively coupled to a propeller so that rotation of the drive shaft by the motor can provide thrust to the watercraft, wherein the propeller can selectively rotate independently of the drive shaft.

Description

PROPELLER FOR POWERED WATERCRAFT

Background of the Invention

[0001] The present invention generally relates to powered watercraft, and in particular but not exclusively to a craft or board with an electric motor and battery.

Prior Application

[0002] The present application claims priority from Australian Provisional Application No. 2021900439 titled “Propeller for powered watercraft” as filed on 19 February 2021, the content of which is hereby incorporated by reference in its entirety.

Description of the Prior Art

[0003] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0004] Recent developments in battery technology have started to make electric watercraft more practical, where high power requirements and the size and weight of batteries previously prevented this. These watercraft tend to be relatively small, such as for use as a backup on a small sail boat or as the primary propulsion source on a rigid inflatable boat, tender, or similar. The propulsion systems are generally in the form of an outboard motor connected to a battery located within the hull.

[0005] One particular form of watercraft that has been developed is the electric surfboard, created by the attachment of a motor to a surfboard, with the battery typically housed within the board. Another similar form of watercraft that is growing in popularity is the electric hydrofoil surfboard or eFoil, created by the attachment of a hydrofoil and a motor to a surfboard, with the battery typically housed within the board. These systems include an electric motor and a hydrofoil in combination, where the hydrofoil elevates the board clear of the water when under power from the motor, reducing drag and providing high speed travel over the water.

[0006] Control of the motor in any of the above examples may be achieved via a hand controller communicating wirelessly with motor control circuitry. Information can also be conveyed back to the user via the hand controller, or by lights on the board, motor, or another location.

[0007] While developments in battery technology and other improvements in efficiency of these watercraft and associated components have made such watercraft more practical, there are still significant performance limitations associated with the battery. For example, these limitations include weight, size, power storage capacity, and cost.

Summary of the Present Invention

[0008] In one broad form of the invention, there is provided an electric powered watercraft, comprising a hull, a battery, a controller, and a motor configured to turn a drive shaft that is operatively coupled to a propeller so that rotation of the drive shaft by the motor can provide thrust to the watercraft, wherein the propeller can selectively rotate independently of the drive shaft.

[0009] In an embodiment, the coupling of the drive shaft to the propeller allows rotation of the propeller relative to the drive shaft in one direction only.

[0010] In an embodiment, the coupling of the drive shaft to the propeller comprises a one way bearing.

[0011] In an embodiment, the one way bearing is housed within the propeller.

[0012] In an embodiment, the one way bearing is a sprag clutch.

[0013] In an embodiment, the one way bearing is a ratchet.

[0014] In an embodiment, the one way bearing is a cam clutch.

[0015] In an embodiment, the one way bearing is a roller clutch. [0016] In an embodiment, the coupling of the drive shaft to the propeller transitions between fixed and relative rotation automatically in response to torque applied to the drive shaft and/or the propeller.

[0017] In an embodiment, the coupling of the drive shaft to the propeller transitions between fixed and relative rotation automatically and independently of the controller.

[0018] In an embodiment, the coupling of the drive shaft to the propeller allows torque to be selectively applied to the propeller by the drive shaft in either direction.

[0019] In an embodiment, the coupling of the drive shaft to the propeller can selectively allow rotation of the propeller relative to the drive shaft in either direction.

[0020] In an embodiment, the coupling of the drive shaft to the propeller comprises a selective one way clutch.

[0021] In an embodiment, the selective one way clutch is operated by the controller.

[0022] In an embodiment, the coupling of the drive shaft to the propeller comprises a sleeve fitted to the drive shaft.

[0023] In an embodiment, the hull is a boat and the motor is in the form of an electric outboard motor.

[0024] In an embodiment, the hull is a board.

[0025] In an embodiment, the controller is removable from the board.

[0026] In an embodiment, the watercraft further comprises a hydrofoil.

[0027] In an embodiment, the hydrofoil and the motor are connected to a mast that extends from the board.

[0028] In an embodiment, the controller is fixed to an upper end of the mast.

[0029] In an embodiment, the controller can be coupled to the board by inserting at least a portion of the controller located at the upper end of the mast into a socket of the board. [0030] In an embodiment, the controller is configured to exchange information wirelessly with an input device.

[0031] It will be appreciated that the broad forms of the invention and their respective features can be used in conjunction and/or independently, and reference to separate broad forms is not intended to be limiting. Furthermore, it will be appreciated that features of the method can be performed using the system or apparatus and that features of the system or apparatus can be implemented using the method.

Brief Description of the Drawings

[0032] Various examples and embodiments of the present invention will now be described with reference to the accompanying drawings, in which: -

[0033] Figure 1 is an isometric view of a watercraft according to an embodiment of the invention;

[0034] Figure 2 is a side view of a hydrofoil, motor, and mast of a watercraft according to another embodiment of the invention;

[0035] Figure 3 is an isometric view of an underside of the watercraft from Figure 1 with a controller removed from the board;

[0036] Figure 4 is an exploded isometric view of a propeller of the watercraft from Figure 1 ; [0037] Figure 5 is a cross sectional side view of the propeller from Figure 4; and [0038] Figure 6 is a cross sectional isometric view of the propeller from Figure 4.

Detailed Description of the Preferred Embodiments

[0039] The following modes, given by way of example only, are described in order to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments.

[0040] In the Figures, incorporated to illustrate features of an example embodiment, like reference numerals are used to identify like parts throughout the Figures. [0041] An example of a watercraft according to an embodiment of the invention will now be described. The watercraft is electric powered and includes a hull, a battery, and a controller. A motor is powered by the battery and operated by the controller. It is configured to turn a drive shaft that is operatively coupled to a propeller, so that rotation of the drive shaft by the motor can provide thrust to the watercraft. However, the coupling also allows for the propeller to selectively rotate independently of the drive shaft.

[0042] This system can be applied to a range of different types of watercraft, but is particularly suitable for relatively small craft, such as for use as a backup on a small sail boat or as the primary propulsion source on a rigid inflatable boat, tender, or similar. In these situations, the propulsion systems will generally be in the form of an outboard motor connected to a battery located within the hull.

[0043] This system can also be particularly appropriate for even smaller watercraft, such as those suitable for only one or two people where the hull is in the form of a board. For example, a powered surfboard.

[0044] Throughout this specification, for the sake of convenience, unless otherwise indicated the term “board” and “hull” may be used interchangeably. Similarly, the invention will be described with particular reference to watercraft where the hull is a board, but this is not intended to be limiting or to indicate that the invention couldn’t also be applied to larger boats with more traditional hulls.

[0045] In this regard, the term “board” is used in a broad sense and is intended to include any suitable form of boat or flotation device. For example, the board may be a rigid structure made from fibreglass, carbon fibre, or other similar materials. It may or may not include a foam or other type of core, similar to a surfboard for example. Alternatively, the board may be softer, such as made primarily from a rigid foam or similar. In still another example, the board may be inflatable or collapsible in some other way, so that it can take a rigid or at least semi-rigid form during use, but can be deflated or otherwise packed down for transport.

[0046] While developments in battery technology and other improvements in efficiency of these watercraft and associated components have made such watercraft more practical, there are still significant performance limitations associated with the battery. For example, these limitations include weight, size, power storage capacity, and cost.

[0047] In the present invention, the coupling that allows the propeller to selectively rotate independently of the drive shaft can be advantageous by improving the efficiency of the overall propulsion system of the watercraft.

[0048] Traditionally, the drive shaft would be rigidly connected to the propeller, either for simplicity or due to the high torque demands of these components. When a signal is sent to the motor to stop producing power, thereby allowing the watercraft to coast, the propeller would create drag as the water flowing past the propeller then begins to turn the drive shaft and associated components.

[0049] By allowing the propeller to rotate freely at certain times in the present invention, it may be possible to reduce drag in situations where the watercraft is moving faster through the water relative to the speed of the propeller as controlled by torque from the motor. Otherwise stated, the propeller can be locked to the drive shaft in one direction when torque is applied by the motor but allowed to “free-wheel” in the opposite direction when the torque is reduced and the watercraft is coasting. This allows the transfer of rotation to the propeller from the motor when powered and when not powered, rotate freely.

[0050] Additional advantages may also be found in examples of the watercraft used in surf, such as a surfboard or hydrofoil board. In these cases, it may be desirable for the user to use the electric motor to catch waves, but afterwards to ride the wave in a similar manner to a regular non-powered surfboard or hydrofoil board. Therefore, allowing the propeller to spin more freely in these situation may provide for a more enjoyable ride that more closely matches that of similar non-powered craft.

[0051] Some other example embodiments of a watercraft will now be described.

[0052] In an embodiment, the coupling of the drive shaft to the propeller may allow rotation of the propeller relative to the drive shaft in one direction only. For example, the coupling of the drive shaft to the propeller may include a one way bearing or a one way clutch mechanism, such as a sprag clutch. It will be appreciated, however, that many different types of one way clutch could alternatively be used, such as but not limited to, a cam clutch, a ratchet, or a roller clutch.

[0053] Generally speaking, one way clutches can be constructed from a drawn cup with needle roller clutches and have a small radial section height. They may also be referred to as one way bearings, anti-reverse bearings and/or clutch bearings. The units are typically compact, lightweight and operate directly on a shaft.

[0054] One way clutches are designed to transmit torque between the shaft and housing in one direction and allow free motion in the opposite direction. Proper mounting can be accomplished with a press fit in the housing. Torque can be transmitted by either the housing or the shaft and is positively transmitted by rollers that wedge against interior ramps. Advantageously, transition from free motion to lock can occur with minimal backlash or lost motion.

[0055] The simplicity of some embodiments is advantageous, as it reduces the possibility of failure in the harsh marine environment. While one way bearings are not normally used for this purpose, modifying these to be manufactured from corrosion resistant materials can allow them to be used in this new application.

[0056] In some example embodiments, the one way bearing can be housed within the propeller. There is relatively little space to package the necessary devices in a hub of the propeller, but this makes such simple mechanisms as described above preferable. Having the bearing within the propeller does also make the requirement of being corrosion resistant to salt water more important, but with the modification described above this can be possible.

[0057] Having the bearing housed within the propeller is also particularly advantageous because it can allow for retrofitting of the present invention to earlier designs that did not include such a feature. This retrofitting procedure may then become as simple as removing the existing propeller and fitting the new design that includes the one way bearing.

[0058] In these or other examples, the coupling of the drive shaft to the propeller can transition between fixed and relative rotation automatically in response to torque applied to the drive shaft and/or the propeller. For example, the transition can occur independently of the controller or any other active response. Instead, the device can be purely mechanical and operate in response to physical inputs from the environment and/or motor.

[0059] In another embodiment, the coupling of the drive shaft to the propeller may allow torque to be selectively applied to the propeller by the drive shaft in either direction. That is, it may be possible for the motor to apply torque in either a forward or reverse direction, while also still allowing for the propeller to rotate relative to the drive shaft in some situations.

[0060] In this or other embodiments, the coupling of the drive shaft to the propeller may selectively allow rotation of the propeller relative to the drive shaft in either direction. For example, the coupling of the drive shaft to the propeller may include a selective one way clutch, so that torque can be applied in either direction and relative rotation can occur in one direction.

[0061] In some examples, the selective one way clutch may be operated by the controller, while in other examples an alternative control mechanism may be provided.

[0062] In an embodiment, a sleeve may be fitted to the drive shaft as part of the coupling of the drive shaft to the propeller. Such a component may be desirable as a wear component, or consumable. For example, a one way clutch may be fitted to the sleeve, and this bearing may rotate against and therefore wear an outer surface of the sleeve. Rather than this wear occurring to the drive shaft itself, which may be difficult to replace, the sleeve may provide for simplified servicing.

[0063] The sleeve may also provide an additional advantage in such an example in that the one way clutch can be a larger diameter, thereby increasing the torque that can be held when locking the propeller to the drive shaft. This advantage can be significant, as this torque can be a limiting factor in the design of such a system.

[0064] It will be appreciated, however, that the sleeve is not essential to the design of the coupling. For example, a one way clutch could be fitted directly to the drive shaft, and the drive shaft could even have a larger diameter at this location if the increased size of the clutch is considered to be of particular importance. Depending on the particular one way clutch or other bearing that is used, wear to the drive shaft may also not be an issue. [0065] In an embodiment, the hull of the watercraft is a board, such as a surfboard for example. In this or other optional examples, the controller may also be removable from the board. There are various reasons why this may be desirable, such as disassembly of the watercraft for transport, or for servicing or replacement of components, for example.

[0066] In an embodiment, the watercraft may include a hydrofoil. For example, the hydrofoil and the motor may be connected to a mast that extends from the hull, or the hull may have a hydrofoil connected separately to an outboard motor or similar.

[0067] In another example, the watercraft may be in the form of an electric hydrofoil board. That is, the watercraft may further include a hydrofoil connected to the board by a mast. The motor may also be connected to the mast proximal to the hydrofoil, or the hydrofoil and motor may be connected to one another so that the hydrofoil is actually connected to the mast by the motor.

[0068] The hydrofoil and connected components could actually take a range of forms, provided it includes one or more components for providing lift, as well as necessary components for providing propulsion. For example, a hydrofoil module may have an integrated motor and wings similar to the present Applicant’s earlier design as described in publication number WO/2019/104378. In this way, the wings are not connected directly to the mast, but rather the wings are connected to the motor housing, which in turn is connected to the mast. Alternatively, the hydrofoil module may take a different form, such as some other known designs where a mast has wings mounted at one location and a motor mounted at a separate location.

[0069] The controller may in fact be fixed to an upper end of the mast, so that removal of the controller in turn also causes the mast, motor and hydrofoil to be removed from the board. For example, the controller may be coupled to the board by inserting at least a portion of the controller located at the upper end of the mast into a socket of the board, similar to that described in the present Applicant’s earlier design published as WO/2019/104379. This could allow very quick and simple assembly and disassembly, while having sufficient strength to withstand the high forces experienced by this connection during use. This connection can also allow for seals to be incorporated relatively easily, to ensure electrical connections are not exposed to water. [0070] In another example of a watercraft, the controller is further configured to exchange information wirelessly with an input device, such as a hand controller. This may be achieved using any suitable wireless protocol and communicators, such as Bluetooth, Bluetooth Low Energy (BLE), or the like.

[0071] The hand controller can function as a user input device for the watercraft, such as by receiving an input through a button or trigger and sending a signal to the controller to choose the level of thrust to be produced by the motor, for example. The hand controller may also be sent information from the controller for display to a user, such as a charge level of the battery, temperature, speed, and any other relevant parameters. This may be the same or different information that is displayed on the deck of the board.

[0072] An example embodiment of a watercraft 100 will now be described with reference to the Figures.

[0073] Referring to Figure 1, the watercraft 100 has a board 110 with a deck 111 that is suitable for a user to lie or stand on when in use. A mast 114 extends from a lower surface of the board 110 and a motor 115 with propeller 116 is connected to a lower end of the mast 114. A main hydrofoil wing 118 and a tail wing 119 are each connected to a body of the motor 115.

[0074] Referring now to Figure 2, the mast 114 and motor 115 setup are shown in more detail. In this case, there is no shroud surrounding the propeller 116.

[0075] Referring to Figure 3, the controller 125 is shown removed from the board 110. In this embodiment, the controller 125 is fixed to the upper end of the mast 114 and can be inserted into a socket 130 of the board 110. Wiring extends along the inside of the mast 114 to connect control circuitry inside the housing 127 to the motor 115 that is located at the opposite end of the mast 114.

[0076] A flange 132 is configured to mate with a rebate 133 in the board 110 and secured in place using fasteners (not shown). The flange 132 forms a watertight seal with the rebate 133 to ensure that no water can enter a space between the housing 127 and the socket 130, maintaining a small air gap between the two. The mast 114 and the flange 132 are constructed from aluminium, while the remainder of the housing 127 is constructed from a plastic. [0077] Once the controller 125 is inserted into the socket 130, an electrical connection provides power from the battery that is located inside the board 110. In the embodiment of Figure 3, this electrical connection includes two pins on the controller 125 which are received in respective apertures 134 in the socket 130. These two conduction paths allow power to be transmitted. However, a preferred alternative embodiment uses leads or cables for this electrical connection, allowing the battery to be connected directly to the controller 125, thereby avoiding the electrical connection to the board 110.

[0078] The controller 125 also includes the relevant components for allowing the watercraft 100 to function, including a microprocessor, a memory, an input/output device in the form of one or more wireless communication devices to exchange instructions with an input device and/or battery, and a logic level motor controller, interconnected by a bus. These components function together to allow the controller to perform tasks including battery management, motor operation, and data output to be displayed to a user.

[0079] The nature of the controller and in particular the physical form factor of the device, as well as the components used, can vary depending on the preferred implementation. For example, the microprocessor and communication device can be formed from a custom integrated circuit, such as a Bluetooth system on a chip (SOC), coupled to, or including an integrated antenna and other optional components, such as the memory.

[0080] The controller 125 is preferably configured to communicate with an input device in the form of a hand controller (not shown). The hand controller is operated by the user and can be used to control the motor speed and to relay data to the user, such as diagnostic and performance information. This may be the same or different information that is displayed on the deck of the board.

[0081] Referring to Figure 4, the propeller setup is shown in more detail. The motor 115 turns a drive shaft 150, either directly or via a gear box as will be generally understood by persons skilled in the art. A sleeve 152 is fitted to the drive shaft 150 and is rotationally fixed relative to the drive shaft 150 by the cross piece 154 and notches 155. The propeller 116 is fitted over the sleeve 152 and held in position by the washer 156 and nut 157 that is threaded onto an end portion 158 of the drive shaft 150. It will be appreciated that alternative fasteners could be used in place of the nut 157 and/or washer 156, such as a split pin or similar, for example.

[0082] Referring now to Figures 5 and 6, a one way bearing 160 is fitted between the sleeve 152 and the inside of a hub 162 of the propeller 116. The bearing 160 allows the propeller 116 to rotate relative to the sleeve 152 and therefore the drive shaft 150 in one direction only. Rotation in the opposite direction is prevented by the bearing 160, allowing the motor 115 to apply torque to the drive shaft 150 which in turn is transferred to the propeller 116.

[0083] In use, the controller 125 operates the motor 115 to provide torque to the drive shaft 150 in a first direction, which in turn rotates the propeller 116 to provide thrust in a forward direction when in water. In this first direction, the bearing 160 locks the propeller 116 to the sleeve 152 and in turn the drive shaft 150.

[0084] In some situations, water may be flowing over the propeller in a manner that creates torque on the propeller 116 that exceeds that being applied by the motor 115 and drive shaft 150. For example, the motor power may be reduced causing the watercraft to coast. In another situation, the rider may catch a wave that causes the watercraft to move through the water at speed even in the absence of power from the motor 115.

[0085] In such a situation, the bearing 160 allows the propeller 116 to spin freely. Therefore, rather than the propeller rotating the drive shaft 150 and associated components, which in turn would create drag in the water, the freely rotating propeller creates very little drag. This in turn allows the watercraft to coast or for the wave to be ridden in a manner that more closely resembles a non-powered craft. This can not only reduce power requirements, but also increase enjoyment by simplifying control of the watercraft.

[0086] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as “front” and “rear”, “inner” and “outer”, “above” and “below” and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms [0087] Throughout this specification and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers. As used herein and unless otherwise stated, the term “approximately” means ±20%.

[0088] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1) An electric powered watercraft, comprising a hull, a battery, a controller, and a motor configured to turn a drive shaft that is operatively coupled to a propeller so that rotation of the drive shaft by the motor can provide thrust to the watercraft, wherein the propeller can selectively rotate independently of the drive shaft.

2) The watercraft according to claim 1, wherein the coupling of the drive shaft to the propeller allows rotation of the propeller relative to the drive shaft in one direction only.

3) The watercraft according to claim 2, wherein the coupling of the drive shaft to the propeller comprises a one way bearing.

4) The watercraft according to claim 3, wherein the one way bearing is housed within the propeller.

5) The watercraft according to claim 3 or claim 4, wherein the one way bearing is a sprag clutch.

6) The watercraft according to claim 3 or claim 4, wherein the one way bearing is a ratchet.

7) The watercraft according to claim 3 or claim 4, wherein the one way bearing is a cam clutch.

8) The watercraft according to claim 3 or claim 4, wherein the one way bearing is a roller clutch.

9) The watercraft according to any one of the preceding claims, wherein the coupling of the drive shaft to the propeller transitions between fixed and relative rotation automatically in response to torque applied to the drive shaft and/or the propeller.

10) The watercraft according to any one of the preceding claims, wherein the coupling of the drive shaft to the propeller transitions between fixed and relative rotation automatically and independently of the controller.

1 l)The watercraft according to claim 1, wherein the coupling of the drive shaft to the propeller allows torque to be selectively applied to the propeller by the drive shaft in either direction. 12) The watercraft according to claim 11, wherein the coupling of the drive shaft to the propeller can selectively allow rotation of the propeller relative to the drive shaft in either direction.

13)The watercraft according to claim 11 or 12, wherein the coupling of the drive shaft to the propeller comprises a selective one way clutch.

14) The watercraft according to claim 13, wherein the selective one way clutch is operated by the controller.

15)The watercraft according to any one of the preceding claims, wherein the coupling of the drive shaft to the propeller comprises a sleeve fitted to the drive shaft.

16) The watercraft according to any one of the preceding claims, wherein the hull is a boat and the motor is in the form of an electric outboard motor.

17)The watercraft according to any one of claims 1 to 15, wherein the hull is a board.

18) The watercraft according to claim 17, wherein the controller is removable from the board.

19)The watercraft according to any one of claims 17 or 18, further comprising a hydrofoil.

20) The watercraft according to claim 19, wherein the hydrofoil and the motor are connected to a mast that extends from the board.

21) The watercraft according to claim 20, wherein the controller is fixed to an upper end of the mast.

22) The watercraft according to claim 21, wherein the controller can be coupled to the board by inserting at least a portion of the controller located at the upper end of the mast into a socket of the board.

23) The watercraft according to any one of the preceding claims, wherein the controller is configured to exchange information wirelessly with an input device.