Abstract
An electric marine propulsion system including steering and vertical position control is provided. The electric drive assembly includes a main drive motor transmitting torque through a shaft to a propeller. The electric drive assembly integrates a dual rudder system positioned ahead of the main drive propeller. The rudder assemblies integrate electric stern thrusters for low-speed maneuvering. The steering and vertical position adjustments for the drive assembly are electrically operated. The electric drive assembly is installed entirely outside the hull of the watercraft.
Claims
1. A watercraft, comprising: a hull extending between a stern and a bow along a longitudinal axis; a surface drive propeller system having a propeller attached to a shaft running along the longitudinal axis; and wherein the shaft is not moveable towards the port and starboard sides of the hull.
2. The watercraft of claim 1, further comprising a rudder system having a rudder configured for movement relative to the longitudinal axis independently from movement of the propeller shaft.
3. The watercraft of claim 2, wherein the surface drive propeller system comprises an electric motor positioned outside the hull for rotating the shaft connected to a propeller, wherein the shaft is configured for running along the longitudinal axis.
4. The watercraft of claim 3, wherein no gear reduction mechanism operably couples the electric motor to the propeller.
5. The watercraft of claim 2, wherein the rudder system comprises at least one rudder, wherein each rudder comprises a propeller surface drive propeller system.
6. The watercraft of claim 5, wherein the propeller of each rudder is controllable independently from the propeller of the main surface drive propeller system.
7. The watercraft of claim 1, wherein each rudder is provided with a hydrofoil for generating lift of the hull during forward operation of the vessel.
8. The watercraft of claim 1, further comprising a drag-reducing cowling positioned below the main drive unit.
9. The watercraft of claim 5, further comprising a software-control system to allow for low-speed operation using the rudder propulsion system only, high-speed operation using only the main drive unit, and hybrid operation allowing for main drive unit and rudder propulsion systems operating together.
10. The watercraft of claim 7, wherein each rudder is positioned within a path of laminar flow of water conditioned by the hull.
11. The watercraft of claim 8, wherein each rudder extends below the hull when viewed from the bow.
12. The watercraft of claim 9, wherein the propeller is not viewable when viewed from the bow.
13. The watercraft of claim 8, wherein the propeller is spaced away from the rudder system such that the propeller does not disturb the laminar flow of the water conditioned by the hull.
14. The watercraft of claim 2, wherein each rudder is configured forwards from the propeller of the surface drive propeller system.
15. The watercraft of claim 11, wherein each rudder is positioned offset from the longitudinal axis.
16. The watercraft of claim 3, wherein the electrical motor is disposed within a sealed housing, and the surface drive propeller system further comprises a cooling system for removing the heat generated within the housing by the electric motor to an exterior of the housing.
17. The watercraft of claim 3, wherein a battery system is connected to the electric motor, the battery system comprising a plurality of battery cells distributed throughout the hull.
18. A method of operating a watercraft comprising: a. controlling a main surface drive motor moveable only in a vertical plane for providing forward thrust to the watercraft; and b. Independently controlling a rudder system for controlling the direction of forward and rearward movement of the watercraft.
19. The method of claim 16, further comprising controlling a motor for rotating a propeller independently from the main surface drive motor.
20. The method of claim 16, further comprising at least one hydro foil for providing a vertical lift force to the stern of the vessel during forward operation.
21. The method of claim 17, further comprising positioning at least one rudder of the rudder system within a laminar flow of water extending from the hull during forward operation.
22. The method of claim 19, wherein the main surface drive motor is configured to drive a propeller positioned away from at least one rudder of the rudder system so that the propeller does not disturb the laminar flow.
23. The method of claim 19, wherein the rudders are offset in the cross-boat direction, so that the water disturbance created by the rudders does not affect the laminar water flow reaching the main drive propeller during forward operation.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] The drawings described herein are for illustrative purposes only of selected non-limiting embodiments and not all possible or anticipated implementations thereof, and are not intended to limit the scope of the present disclosure.
[0041] FIG. 1A is a rear perspective view and illustrates a watercraft with an electric propulsion system.
[0042] FIG. 1B is a side view and illustrates a watercraft with an electric propulsion system.
[0043] FIG. 2 is a rear perspective view and illustrates an electric propulsion system installed on a watercraft.
[0044] FIG. 3 is a vertical section view through the centerline of a watercraft and illustrates an electric propulsion system installed on a watercraft.
[0045] FIG. 4 is a front view of a watercraft and illustrates the spatial relationship of the rudders and hydrofoils to the hull of the watercraft.
[0046] FIG. 5 is a rear view of a watercraft with an electric propulsion system and illustrates the spatial relationship of the rudder propulsion systems to the main drive propulsion and the hull of the watercraft.
[0047] FIG. 6 is a rear perspective view of a rudder assembly illustrating an integrated electric propulsion system and hydrofoil features.
[0048] FIG. 7A is a vertical section view through the centerline of a rudder assembly illustrating an integrated electric propulsion system and water sealing features.
[0049] FIG. 7B is a vertical section view through the centerline of a rudder assembly illustrating an integrated electric propulsion system and water sealing features.
[0050] FIG. 8 is a rear perspective view through the centreline of a rudder assembly with integrated hydrofoil features.
[0051] FIG. 9 is a schematic illustrating a method of operating an electric propulsion system of a watercraft in multiple modes according to aspects of this disclosure.
[0052] FIG. 10 is a flowchart illustrating steps of a method of operating an electric propulsion system of a watercraft in multiple propulsion modes according to aspects of this disclosure.
[0053] FIG. 11A is a front perspective view of an electric marine propulsion system.
[0054] FIG. 11B is a front perspective view of an electric marine propulsion system illustrating the cooling system.
[0055] FIG. 12A is a front view of an electric marine propulsion system illustrating the cooling system channels.
[0056] FIG. 12B is a rear perspective view of the main drive casting illustrating the external cooling surfaces.
[0057] FIG. 12C is a rear perspective section view of the main drive casting illustrating the internal cooling channels and external cooling surfaces.
[0058] FIG. 13 is a front perspective view a watercraft illustrating a distributed battery pack system.
[0059] FIG. 14A is a rear perspective view of an electric propulsion system installed on a watercraft transom and illustrating a drag-reducing cowling
[0060] FIG. 14B is a vertical section view through the centerline of an electric propulsion system installed on a watercraft illustrating the relationship of the drag-reducing cowling to the hull and the electric propulsion system.
[0061] FIG. 15A is a top view of an electric propulsion system installed on a watercraft illustrating the water flow characteristics with respect to the rudders and main drive propeller.
[0062] FIG. 15B is a side view of an electric propulsion system installed on a watercraft illustrating the water flow characteristics with respect to the rudders and main drive propeller.
[0063] FIG. 16A is a top view of an electric propulsion system installed on a watercraft illustrating the water flow characteristics with respect to the stern thrusters and main drive propeller during forward motion.
[0064] FIG. 16B is a side view of an electric propulsion system installed on a watercraft illustrating the water flow characteristics with respect to the stern thrusters and main drive propeller during forward motion.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0065] Example embodiments will now be described more fully with reference to the accompanying drawings. To this end, the example embodiments are provided so that this disclosure will be thorough, and will fully convey its intended scope to those who are skilled in the art. Accordingly, numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. However, it will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the present disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
[0066] As best shown in FIGS. 1A AND 1B, the present disclosure describes an electric surface drive propulsion system 2 mounted completely externally to a watercraft 1. The propulsion system is fixed to the watercraft by means of bolts or other mechanical fasteners. The propulsion system is attached to the transom by means of a transom mounting plate 3. The main drive unit 7 and the linear mechanical actuator 5 are attached to the transom mounting plate 3.
[0067] As shown in FIG. 2, the propulsion system is connected to the transom by means of a transom mounting plate assembly 3. The main drive unit 7 and the linear mechanical actuator 5 are connected to the transom mounting plate assembly 3. The propulsion system integrates the linear electric mechanical actuator 5 used for controlling the vertical orientation of the main drive unit 7. The propulsion system integrates the linear electric mechanical actuator 4 used for controlling the rudder(s) 9 orientation relative to the watercraft. The electric linear actuators 4 and 5 eliminate the need for a hydraulic actuator control system as used in some systems. By this electric actuator method, complexity, weight and maintenance requirements are reduced over a hydraulic system. The moveable rudder(s) 9 are mounted to the main drive assembly 7 and change their vertical orientation as the vertical orientation of the main drive unit is changed. In this way, the lifting hydrofoil(s) 10 remains parallel to the main drive unit shaft axis. Since the main shaft/prop axis surface drive propulsion system is typically operating parallel to the water's surface, the lifting hydrofoil also operates parallel to the water's surface. By this method, the lifting hydrofoil(s) 10 provides an upward force to the transom during forward operation. Since the surface drive propulsion system does not provide lift force to the watercraft during forward operation, the lifting hydrofoil(s) 10 are incorporated so the operator of the watercraft can vary the orientation of the hull with respect to the water's surface during forward operation by changing the vertical orientation of the main drive unit 7. The main drive unit 7 can be angularly adjusted in vertical orientation only through the activation of the non-back driveable linear mechanical actuator 5, and steering control is accomplished through the separately-operable rudder(s) 9 assemblies. The rudder(s) 9 assemblies integrate a low-speed propulsion system 8 into the rudder casting 9. The rudder 9 is cast from an aluminum alloy such as 5083. Surface drive propulsion systems are inherently difficult to control during low-speed maneuvering due to the extended distance between the propeller and the transom. By integrating the low-speed propulsion system 8 into the rudder 9 assembly, the propulsion unit is optimized for low-speed docking and trolling operations. The low-speed 8 and high-speed 7 propulsion systems are separately operable from each other through the control system as described in FIG. 9 and FIG. 10.
[0068] As shown in FIG. 3, the main drive unit 7 and associated steering 4 and vertical orientation 5 actuators are located externally to the hull. This method optimizes the usable floor space inside the watercraft, since no motor is required internally to the watercraft hull. This method also reduces the noise perceptible to the watercraft operators. The transom 11 of the watercraft 1 is used for structural attachment of the propulsion system 2. A distributed battery pack system 16 is installed internally to the watercraft hull to provide power to the all-electric drive and control system. An electric motor 12 is used to rotate the main drive propeller 6. No gear reduction is designed into this system in order to optimize performance. The main drive electric motor operates from 0 RPM to approximately 4000 RPM, which is ideal for most watercraft applications. Since an externally-mounted drive system is relatively large and produces unwanted drag during forward operation, a drag-reducing cowling 13 is described. The drag-reducing cowling 13 is geometrically designed to reduce hydrodynamic drag, and may be injection-molded from a polymer such as PC-ABS. The drag-reducing cowling 13 is coated with a drag-reducing hydrophobic coating to reduce frictional drag during forward operation of the watercraft. The drag-reducing cowling 13 remains fixed to the external transom mounting plate assembly 3. The main drive unit 7 is vertically adjustable. By this method, the leading surface of the main drive unit 7 remains out of the water flow during forward motion, and therefore drag is reduced. A flexible EPDM rubber bellows 14 is used to provide a waterproof path for power and signal wires between the internal hull electronic modules and battery packs 16 and the externally-mounted propulsion system. The main drive motor 12 must be vented to atmosphere for optimal operation, so the rubber bellows 14 additionally provides a venting path between the main drive motor 12 housing and the internal transom dry side. Venting the main drive motor 12 to the internal dry side of the transom is the optimal venting method since it reduces the risk of water ingress to the main drive motor 12.
[0069] As shown in FIG. 4, the rudder(s) 9 and the lifting hydrofoil(s) 10 are designed to protrude below the bottom of the hull of the watercraft 1. This method provides for minimized drag during forward operation, since the main drive unit 7 is shielded by the hull of the watercraft 1.
[0070] As shown in FIG. 5, the main drive propeller 6 is located on center of the watercraft 1, and vertically located to optimize the propeller location relative to the water's surface during forward high-speed motion. In a surface drive propulsion system, the propeller is designed to be only partially submerged during forward operation in order to increase propeller efficiency by reducing the effects of cavitation. The low-speed propulsion system(s) 8 is offset vertically and horizontally from the main drive propeller 6. In using this offset method, the turbulence created by the rudder(s) 9 and the low-speed propeller(s) 8 does not affect the laminar water flow reaching the main drive propeller 6. Therefore, main drive propeller performance is optimized.
[0071] As shown in FIG. 6, a rudder 9 assembly integrates a hydrofoil structure 10 and a low-speed electric propulsion system 8.
[0072] As shown in FIGS. 7A and 7B, the low-speed propulsion system integrated into the rudder 9 casting includes an electric motor 19, a thrust bushing assembly 22, a shaft sealing system 21, a cover sealing system 23, and a motor control and power wire harness 18. At assembly, the cavity 20 is encapsulated with a water sealing and thermally-conductive potting compound to prevent water ingress to the motor and provide heat transfer between the electric motor 19 and the aluminum rudder 9 casting.
[0073] As shown in FIG. 8, a rudder 24 assembly without integrating a low-speed electric propulsion system. This rudder assembly is ideal for high-performance applications such as racing boats since it minimizes drag by reducing the rudders cross-sectional area.
[0074] Shown in FIG. 9 is a method of operating a watercraft using three operator-selectable modes with the propulsion hardware as described in this disclosure. The operator of the watercraft can select from three modes of propulsion. Mode 101 involves supplying power to only the rudder 8 stern thruster(s). This mode may be used for low-speed docking operations, fishing operations such as trolling, and low-speed cruising for example. Mode 102 involves supplying power to only the main drive unit 7. This mode may be used for high-speed watercraft operation. Mode 103 involves pre-programmed software control of both the stern thruster(s) 8 and the main drive unit 7. Mode 103 is used for optimal performance during watercraft acceleration from rest, for example. During watercraft acceleration from rest, the stern thruster(s) 8 and the main drive unit 7 are powered on for maximum acceleration. Once the watercraft has accelerated and is on plane, the stern thruster(s) 8 are powered off through software control, thereby minimizing power consumption. Sensors 107, 108, and 109 are used to determine the watercraft real-time performance, and thereby provide feedback to the software control system.
[0075] Shown in FIG. 10 is a logic flow chart describing the propulsion system response as a result of the drive mode selected. The watercraft operator has the option of three selectable propulsion modes. Once the software system receives the desired selection from the watercraft operator, the selected propulsion mode is enabled as detailed.
[0076] Shown in FIG. 11A is the main drive unit assembly illustrating
[0077] Shown in FIG. 11B is the internal motor and cooling system detail, since the front cover plate has been removed. The main drive motor 12 has an internal circuit for cooling fluid flow. The main drive motor 12 is fixed to the main casting through mounting plate 25. The cooling inlet hose 26 is attached the main drive motor 12 and the coolant pump 28. A hose attaches the coolant pump 28 to a fitting on the covering plate 29.
[0078] Shown in FIG. 12A are the cooling channels 28 integrated into the main drive aluminum casting. The coolant pump 28 is not shown for clarity. The coolant fluid is circulated through the main drive motor 12 cooling circuit and routed into the cooling channels 28. The cooling channels are sealed off using a covering plate 29 and gasket (not shown). Thermal energy is conducted from the fluid into the main drive casting 7, and exterior cooling fins 29 in FIG. 12B are designed to transfer the thermal energy to the external environment through convection and conduction to the water spray on the exterior surface of the main drive casting 7. FIG. 12C details the internal cooling channels and the external cooling fins. The main drive motor 12 thermal performance is optimized through using the main drive casting 7 as a thermal reservoir. At higher speeds the water spray on the main casting 7 provides conductive cooling to the exterior cooling fins 29. At low speed, the main drive unit 2 is largely submerged, provide optimal motor cooling through conduction of the aluminum main drive casting.
[0079] FIG. 13 shows a distributed battery pack system. One battery pack 16 is designed to be 436 volts, and 5 amp-hour. The battery packs are connected in parallel through a wiring harness 30 to provide additional battery capacity at 436 volts. The battery packs 16 are designed to be manually removed from the watercraft if necessary. During winterization, it is advantageous to remove the battery packs from the watercraft for storage if the watercraft is to be stored in cold temperatures. The distributed battery pack system allows for battery pack 16 removal for winterization or battery pack 16 replacement. Additionally, distributed battery packs allow for mass balancing inside the watercraft to optimize watercraft performance.
[0080] FIGS. 14A and 14B illustrate the drag-reducing cowling 13 fixed to the external transom mounting plate assembly 3. The drag-reducing cowling 13 minimizes drag caused by the main drive unit assembly 2 during forward motion of the watercraft. The drag-reducing cowling is manufactured from a low-friction polymer such as PC-ABS, and is coated with a hydrophobic coating to minimize drag.
[0081] FIGS. 15A and 15B show the water flow under the watercraft 1 during forward motion with the watercraft 1 on plane and only the main drive propeller 6 powered on. The flow disturbances created by the rudder(s) 9 will not affect the thrust performance of the main drive propeller 6 since the rudder(s) are offset from the centerline of the watercraft 1.
[0082] FIGS. 16A and 16B show the water flow under the watercraft 1 during forward motion with the watercraft 1 on plane and both the rudder(s) 8 propulsion and main drive propulsion 6 powered on. The flow disturbances created by the rudder(s) 9 will not affect the thrust performance of the main drive propeller 6 since the rudder(s) are offset from the centerline of the watercraft 1 in the horizontal direction.
[0083] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
