Keel drive assembly for propelling and maneuvering a boat

Abstract

A unitary hermetically sealed device is disclosed for providing self-contained electric propulsion drive power to a motor boat or sailboat, where the entire propulsion system is contained in a separable pressurized hermetic enclosure attached to the underside of the vessel and also acts as a keel of the vessel, and which simplifies production, provides improved safety from high voltages, and prevents drive system maintenance or repair when the vessel is located in the water. The rigid hermetically sealed device functions as a skid-plate to avoid damage to the softer typically fiberglass hull when running the vessel aground or when running up onto or off of the beach or onto or off a trailer.

Claims

1. An electric drive system for a boat that is completely encapsulated inside a hollow keel, attached to the underside of a marine vessel, wherein the keel is hermetically sealed and the electric drive system components are inaccessible while the boat is located in the water, comprising: propeller propulsion system; battery storage; power electronics; control electronics; and the hermetically sealed keel system is filled with a fluid, wherein the fluid is used to: improve the heat transfer between the components inside the hollow keel and the water surrounding the keel, indicate any leaks in the hermetic seal, and prevent combustion inside the system.

2. The electric drive system of claim 1, where the propeller propulsion system, power electronics and control can also be used to generate power by the spinning of the propeller to provide regenerative power back into the battery system.

3. The electric drive system of claim 1, where the fluid is pressurized.

4. The electric drive system of claim 1, wherein the fluid is non-flammable.

5. The electric drive system of claim 1, wherein the fluid is an oxygen free gas.

6. The electric drive system of claim 1, wherein the fluid is a dielectric fluid.

7. The electric drive system of claim 1, wherein the fluid is composed of one or more refrigerants.

8. The electric drive system of claim 3, wherein a change in pressure inside the hermetic enclosure is used to determine a problem and initiate shut down.

9. The electric drive system of claim 1, wherein a change in temperature of the fluid is used to determine a problem and initiate shut down.

10. The electric drive system of claim 5, wherein the oxygen free gas is selected from the group consisting of nitrogen, argon, helium, and neon.

11. The electric drive system of claim 3, wherein when the internal pressurized fluid causes an increase in heat transfer cooling to the internal skin of the keel.

12. The electric drive system of claim 1, wherein the keel is mounted to the bottom of the boat with fasteners.

13. The electric drive system of claim 12 where the mounting is accomplished with releasable fasteners.

14. The electric drive system of claim 13, wherein the releasable fasteners are selected from the group consisting of thermal fracturing bolts and explosive bolts.

15. The electric drive system of claim 1, wherein the keel is mounted to receiver with one or more fasteners, in such a way to allow the keel to partially or fully retract or swing into the inside of the receiver and the receiver is then mounted to or part of the hull of the boat.

16. The drive system of claim 15 where the mounting is accomplished with releasable fasteners or a fastening pin.

17. The electric drive system of claim 16, wherein the releasable fasteners or pin are selected from the group consisting of thermal fracturing and explosive fasteners and pins.

18. The electric drive system of claim 1, further comprising: a first inductive coupling for command-and-control communications between the boat and the components in the keel.

19. The electric drive system of claim 18, further comprising: a second inductive coupling for power extraction, shore power battery recharging and for other loads in the sailboat.

20. The electric drive system of claim 1, where internal components in the keel are un-accessible when the keel is mounted to the boat with an access opening that is only exposed when the boat is removed from the water and the keel is removed from the boat.

21. The electric drive system of claim 1, where the interior surface of the hollow keel contains fins to increase heat transfer.

22. The electric drive system of claim 1, where the exterior surface of the hollow keel contains fins to increase heat transfer.

23. The electric drive system of claim 1, where the hollow keel contains one or more fittings to allow the hollow keel to be flooded with water when the keel is attached to the boat and the boat is in the water.

24. The electric drive system of claim 23, where the fittings consist of one or more pressure bursting or temperature bursting fittings that open when exposed to excessive temperature or pressure.

25. The electric drive system of claim 23, where the fittings consist of one or more fusible plugs that open when exposed to excessive temperature.

26. A hollow keel forming a void therein and which the keel is completely sealed and any internal components in the keel are un-accessible when the keel is mounted to the boat with an access opening that is only exposed when the boat is removed from the water, and the keel is removed from the boat; wherein the hollow keel is filled with all the necessary electric drive and regenerative energy capture components including but not limited to battery, motor, power electronics, and control electronics, and wherein the void inside the hollow keel is filled with a fluid.

27. The hollow keel of claim 26, wherein the fluid is pressurized between 0.0 psig and 200 psig.

28. The hollow keel of claim 26, wherein the fluid is an oxygen free gas.

29. The hollow keel of claim 28, wherein the oxygen free gas is selected from the group consisting of nitrogen, argon, neon, helium, and refrigerants.

30. A hollow keel forming a void therein and which the keel is completely sealed and any internal components in the keel are un-accessible when the keel is mounted to the boat with an access opening that is only exposed when the boat is removed from the water, and the keel is removed from the boat, wherein the void is filled with a dielectric liquid.

31. The hollow keel of claim 30, wherein the liquid is pressurized between 0.0 psig and 200 psig.

32. The hollow keel of claim 30, wherein the liquid is selected from the group consisting of oil, refrigerant, or other dielectric fluids.

33. A hollow keel forming a void therein and which the keel is completely sealed and any internal components in the keel are un-accessible when the keel is mounted to the boat with an access opening that is only exposed when the boat is removed from the water, and the keel is removed from the boat, wherein the void inside the keel is filled with a mixture of a liquid and a gas, wherein the mixture is pressurized to a pressure at or above atmospheric pressure.

34. The hollow keel of claim 33, wherein the mixture is pressurized between 0 psig and 200 psig; wherein the gas is selected from the group consisting of nitrogen, argon, neon, helium and refrigerant; and the liquid is selected from the group consisting of oil, refrigerant, and a dielectric fluid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features, aspects, and advantages of the disclosure will become better understood given the following description, appended claims, and accompanying drawings where:

(2) FIG. 1 shows an isometric rendering of many of the possible components of a deep-draft KDA bolted to the bottom of a boat, most likely a sailboat.

(3) FIG. 2 shows an isometric rendering of a low-draft version of the KDA mounted to the bottom of a boat, most likely a power boat.

(4) FIG. 3 shows an isometric view of a lifting-keel version of the KDA mounted to the bottom of a boat, most likely a sailboat.

DESCRIPTION

(5) In the Summary above and the Description, and the claims below, and in the accompany drawings, reference is made to particular features (including method steps) of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular aspect or embodiment of the invention, or a particular claim, that feature can also be used, to the extent possible, in combination with and/or in the context of the other particular aspects and embodiments of the invention, and in the invention generally.

(6) Now referring to the FIG. 1, in one implementation, the KDA 10 for a boat is connected to the bottom of the boat 15 with mounting bolts 20. Bolts 20 can be of the type that are standard fasteners that can resist the corrosive effects of water or quick release fasteners. If the bolts 20 are of the quick release fastener type, then in one implementation the fasteners can be thermal fracturing bolts or explosive bolts. Such bolts provide an advantage of in case of fire within the KDA, the KDA can be jettison from the boat and thus prevent the fire from entering into the boat. As stated earlier, as an alternative to jettisoning the KDA, burst disks 25 (or the like, such as fusible plug or electrically activated solenoid valve) on the KDA could be used to allow the surrounding water to enter the void space inside the KDA and flood the KDA.

(7) In one implementation, communication cable 110 can be passed through the hull of the boat 15 and the KDA 10. Likewise in one implementation, a power line cable 115 can be passed between the hull of the boat 15 and the KDA 10.

(8) In one implementation, the KDA 10 has a drive tunnel 30 located between the top and bottom of the KDA. The drive tunnel 30 contains the motor/generator 40 and propeller 50. When water current is flowing through the drive tunnel 30 the propeller 50 rotates and that rotation cause the motor/generator 40 to generate electricity which can be used to both charge the batteries 80 and provide electrical power to the boat. When the operator of the boat wishes to propel the boat, the operator can switch the motor/generator 40 into motor operation and propel the boat forward under battery power.

(9) In one implementation, to further assist in maneuvering the boat, the KDA 10 contains a forward thruster 60 and an aft thruster 70. Forward side-thrusters 60 and aft side thrusters (one on each side) 70 that are powered by the batteries 80.

(10) In one implementation, the KSA 10 positions the batteries 80 at the bottom of the KDA. Positioning the batteries at the bottom provides stability to the boat and lowers the center of gravity of the boat. A thermal communication path or cold plate 81, sandwiched between the batteries 80 and thermally attached to the inside skin of the KDA10 and can be used to maintain the battery temperature at or around the temperature of the water surrounding the vessel. If direct mechanical attachment to the interior surface of the KDA is not practical, a thermal connector, comprised of a thermal strap, heat pipe, liquid loop or other heat transfer means can be used to transfer heat between the battery and the water surrounding the KDA, by conducting heat between the devices or their cold plates and the interior skin of the KDA. The external skin of the KDA 10 is used to provide heat transfer between the KDA and the water surrounding the KDA. It is of course also understood that the external surface of the KDA can be finned 130 to increase heat transfer between the external surface of the KDA and the surrounding water. For a smaller boat that can potentially be trailered on land and recharged when on the trailer, the external heat transfer fins on the KDA can be used to enhance heat transfer between the KDA and the air surrounding the KDA, when the boat is being recharged on a trailer.

(11) The void inside the KDA can also be filled with a conducting fluid, saturated fluid, or liquid vapor mixture to convectively and conductively transfer heat between the surrounding water and the contents of the KDA, including the batteries, electronics, motors, and the like. In the preferred embodiment a combination of these methods are used with cold plate cooling for the batteries and conduction and convection cooling for the remaining components inside the KDA. A fan (or pump not shown), can be used to circulate the fluid contained inside the KDA to increase the convective heat transfer, that is to achieve forced convection heat transfer.

(12) The KDA 10 contains power electronics 90. Power electronics 90 regulate the power between the batteries 80 and the motor/generator 40. Inductive transformer coil 180 in the KDA 10 and another inductive coil 185 inside the boat hull 15 can be used to transfer two-way electrical power between the regenerative keel drive assembly 10 and the boat instead of or in addition to using the power cable 115. When KDA 10 is in regenerative mode, power electronics 90 distributes power from the motor/generator 40 to the batteries 80 to charge the batteries 80. When the operator decides to propel the boat, the power electronics 90 distributes power from the batteries 80 to the motor/generator 40 in order to rotate the propeller 50. The inductive coil pair 180 and 185 is also used to recharge the batteries when the boat is at the dock and connected to shore power and used to supply power to the accessories in the boat by drawing power from the batteries 80 of the KDA 10.

(13) The rudder of the boat can be cantilevered off the aft end of the KDA, located at the trailing end of the drive tunnel, or attached to the boat and not attached to the KDA. The rudder used in the FIG. 1 configuration would be attached to the downstream end of the boat and is not shown.

(14) The KDA 10 contains control electronics 100. Control electronics 100 are designed to transfer two-way command and control information between the boat to the KDA 10 through the communications cable 110, a second pair of inductive coils not shown, or the inductive transformer coils 180 and 185 used to transfer electrical power can also be used to transfer command and control instructions as well as power by using the power-line transmission method. Command and control communications maintain and report the battery state of charge, respond to navigational and propulsion commands from the boat, monitor for adverse problems with the drive system, monitor internal temperature and internal KDA gas pressure, and check for excessive power draw, voltage anomalies, and current anomalies. Control commands include, but are not limited to, engaging regenerative mode, propulsion mode, maneuvering mode. It is of course understood, that other means of wireless communication, including radio and Bluetooth communication between the vessel and the hermetically sealed KDA could be used to transmit control and status information between the operator in the vessel and the devices inside the KDA that react to the stated commands.

(15) The KDA contains a pressurized fluid 150 that completely fills all void spaces inside the KDA 10. Pressure transducer 120 is used to measure the pressure of the fluid within the KDA 10. Any change in pressure is sensed by the pressure transducer 120. If the pressure is changed to a point that such a change signals a problem with the KDA 10, then shut down of the system can be initiated. Temperature transducer 125 is used to measure the temperature of the fluid within the KDA 10 and/or temperature transducer 126 is used to measure the temperature of the batteries or battery cold plate. Any change in temperature is sensed by the temperature transducer 126 mounted to the cold plate 81 or temperature transducer 125 immersed in the fluid contained in the KDA. If the temperature is changed to a point that such a change signals a problem with the KDA 10, then shut down of the system can be initiated. If a saturated fluid is used within the KDA, then the temperature of the saturated fluid could be determined by the pressure transducer in the system, so a pressure transducer could be used for both pressure and temperature monitoring.

(16) The fill port 160 is used to fill the internal structure of the KDA with the pressurized gas or liquid or mixture of gas and liquid. The location of the fill port is not critical so long as the internal structure can be filled appropriately, in the preferred embodiment, even when the KDA is attached to the hull of the vessel.

(17) In one implementation, KDA 10 contains internal heat transfer fins 140. The fins 140 facilitate convective heat transfer between the fluid contained in the internal portion of the KDA to the internal side of the skin of the KDA and then via conduction through the skin to the external surface of the KDA and then into the surrounding water.

(18) If servicing the KDA 10 is desired, then a removable access port or cover (not shown) is provided to permit access to the internal components only when the boat is out of the water, the KDA is detached from the boat and the cover is then exposed.

(19) Similar to the sailboat application, the KDA can also be fitted to a power boat and configured in a similar manner, FIG. 2. For example, the KDA can span a portion or run the entire length of the bottom of the vessel and there can also be thrusters located fore and aft on the KDA. Since the rigid KDA in the power boat application would typically be of similar length or longer but also much wider and far less deep, two drive tunnels 201, 202 would be a preferred configuration with individual rudders 203 and 204 located at the rear most end of the drive tunnels or a single rudder aft of the KDA but in the propellor's outwash could be used, and this single rudder could be attached to the KDA (not shown) or instead attached to the hull of the boat 205. Attaching the rudder 205 and therefore control of the rudder on the boat hull instead of on the KDA, simplifies the design of the KDA, and simplifies the propulsion control of the KDA. The lack of protrusions on the underside, allow the KDA to also function as a skid-plate and allow a portion of the boat to slide up and down on the shore, simplifying beach access (and trailer mounting) without damage to the typical fiberglass (softer and less resilient) hull of a conventional motor boat.

(20) Referring to the FIG. 2, and like the sailboat application, in one implementation, the KDA 210 for the power boat application is once again connected to the bottom of a power boat hull 215 with mounting bolts 220. Bolts 220 can be of the type that are standard fasteners that can resist the corrosive effects of water or quick release fasteners. Alternatively burst disks can still be employed in this application to flood the KDA if serious fires or other issues occur.

(21) In the FIG. 2 implementation of the KDA, a Vee Configured keel 210 has a two drive tunnels 201 and 202. Each drive tunnel contains a motor/generator and propeller that are not shown. When water current is flowing through the drive tunnels the propellers rotate and that rotation causes the motors/generators to generate electricity which can be used to both charge the batteries 80 and provide electrical power to the boat. When the operator of the boat wishes to propel the boat, the operator can switch the motor/generator into motor operation and propel the boat forward under battery power.

(22) In one implementation, to further assist in maneuvering the boat, the KDA 210 contains a forward thruster 242 and an aft thruster 241 powered by batteries 80 within the KDA.

(23) In one implementation, the KDA 210 positions the batteries 80 at the bottom of the KDA. Positioning the batteries at the bottom provides stability to KDA and thus the boat attached to the KDA. Thermal communication paths or cold plates 81, sandwiched between the batteries 80 can be used to maintain the battery temperature at or around the temperature of the water surrounding the vessel. The void inside the KDA can also be filled with a conducting fluid, saturated vapor, or liquid vapor mixture to convectively and conductively transfer heat between the surrounding water and the contents of the KDA, including the batteries, electronics, motors and the like. In the preferred embodiment a combination of these methods are used with cold plate cooling for the batteries and conduction and convection cooling for the remaining components inside the KDA. A fan or pump (not shown) can be used to circulate the fluid contained inside the KDA to increase the convective heat transfer, that is to achieve forced convection heat transfer.

(24) The KDA 210 for the motor boat, like the sailboat, contains power electronics and control electronics located inside the KDA (not shown). Power electronics regulate the power between the batteries 80, the one or more motor/generators and the one or more inductive transformer coils.

(25) The FIG. 2 KDA design in only one preferred power boat KDA configuration anticipated by the proposed invention, where the KDA 210 has more of a Vee Stepped Configuration typical of many planing power boats. Naval Architects well versed in the art could utilize any number of typical hull shapes, from various stepped and un-stepped vee configurations, to more flat bottom designs. Lifting foils could also be incorporated into the KDA design shape.

(26) FIG. 3 shows one embodiment of a conventional type of lifting keel design, connected to the bottom hull well known in the art where a hydraulic ram 320 lifts the keel up and down. The bulb or base of the typical keel 396 is attached to a narrow foil shaped protrusion 397 which moves up and down by the action of the hydraulic ram 320 and is guided by multiple glide blocks or linear bearings 390, and rides inside a pocket 395 which can be totally inside or outside of the hull 314, or contained partially inside and partially outside the hull 314 as shown in FIG. 3. In one embodiment of my design of the KDA, the hydraulic pump 330 and hydraulic electric motor 340 that powers the hydraulic pump and all the associated power electronics 311 and control electronics 312 are packaged inside the base of the keel 396 and forms the KDA. This base, which is the hermetically sealed KDA, 396 lifts up (or swings-up not shown) into the pocket 395 of the boat's hull 314. Hydraulic supply (keel up) 370 and return (keel down) 375 lines provide the hydraulic power to actuate the hydraulic piston 321 which is inside the overall hydraulic piston assembly 322, to cause the ram 320 to recede into or extend outward from the hydraulic assembly 322. When hydraulic pressure is supplied to the bottom of the piston 321 by hydraulic line 370 and hydraulic fluid returns to the hydraulic pump 330 via hydraulic line 375 the ram 320 recedes into the hydraulic piston assembly and the keel is lifted. When hydraulic pressure is supplied to the top of the piston 321 by hydraulic line 375 and hydraulic fluid returns to the hydraulic pump 330 via hydraulic line 370 the ram 320 extends from the hydraulic piston assembly and the keel is lowered. The KDA 396 contains power electronics 311. Power electronics 311 regulate the power between the batteries 380, the hydraulic pump motor 340 and the motor/generator 345 which rotates the propeller 350 via motor shaft 346. When KDA 396 is in regenerative mode, power generated by spinning the propeller is managed by the power electronics electronics 311 which then distributes power to the batteries 380 to charge the batteries 380. When the operator decides to propel the boat, the power electronics 311 distributes power from the batteries 380 to the motor/generator 345 in order to rotate the propeller 350. This FIG. 3 embodiment shows the propeller outside the KDA rather than packaged inside a drive tunnel as was shown in FIGS. 1 and 2. Either configuration is within the scope of this invention. For this type of sailboat application, the rudder 315 of the boat is cantilevered off the aft end of the sailboat hull and not part of the KDA, or any part of the keel lifting structure of FIG. 3. The KDA 396 contains control electronics 312. Control electronics 312 are designed to transfer control commands from the boat to the KDA 396, maintain and report the battery state of charge, respond to propulsion commands from the boat, respond to keel lift and drop commands from the boat, monitor for adverse problems with the drive system, monitor internal temperature and internal KDA gas pressure, and check for excessive power draw, voltage anomalies, and current anomalies. Control commands include, but are not limited to, engaging regenerative mode, and propulsion mode, and activating the hydraulic motor 340 and drive motor 345. It is of course understood, that wireless communication, including radio and Bluetooth communication between the vessel and the hermetically sealed KDA could be used to transmit control and status information between the operator in the vessel and the devices inside the KDA that react to the stated commands. The KDA contains a pressurized fluid 351. Pressure transducer 352 is used to measure the pressure of the fluid within the KDA 396. Any change in pressure is sensed by the pressure transducer 352. If the pressure is changed to a point that such a change signals a problem with the KDA 396, then shut down of the system can be initiated. Temperature transducer 353 is used to measure the temperature of the fluid within the KDA 396 and/or the temperature of the batteries or battery cold plate. Any change in temperature is sensed by the temperature transducer 353 and if the temperatures changes to a point that signals a problem, then shut down of the system can be initiated. If a saturated fluid is used within the KDA, then a temperature and pressure of the saturated fluid could be determined by either the pressure transducer or temperature sensor in the system, so a single measurement of either temperature or pressure transducer could be used for both pressure and temperature monitoring. The fill port 381 is used to fill the internal structure of the KDA with the pressurized gas or liquid or mixture of gas and liquid 351. The location of the fill port is not critical so long as the internal structure can be filled appropriately, in the preferred embodiment, even when the KDA is attached to the hull of the vessel. If servicing the KDA 396 is desired, then a removable access port or cover (not shown) preferably located under the connecting pin 310 is provided to permit access to the internal components only when the boat is out of the water, the KDA is detached from the boat by removing the connecting pin 310 and the cover is then exposed. If it was desired to jettison the KDA 396 in this configuration, the preferred option is to release connecting pin 310. As with other KDA configurations, a thermal fusible plug or burst disk could be used to automatically flood the interior of the KDA 396, should a temperature of pressure extreme be reached.

(27) Some example calculations on the size of the battery pack for one preferred sailboat embodiment, would be useful at this time. Assuming a 34-foot sailboat with a total displacement of 14,000 pounds. To get such a boat quickly onto a plane would require about 420 horsepower (HP). Assuming a conservative specific energy of the battery pack at 74 W-hr/kg, specific power of 185 W/kg and energy density of 185 W-hr/liter and an overall conversion efficiency of 80%, then approximately 12,000 pounds of batteries would be required to provide sufficient power to get the sail boat up on a plane for about 1 hour. Alternatively, this would provide an auxiliary powered displacement boat ride of about 20 hours, with the motor producing about 20 Hp shaft power. This battery weight and the resulting overall KDA weight is appropriate for a sailboat of this size. These batteries would occupy about 71 cubic feet, so for a shallow draft design with a draft of about 4.4 feet, an average KDA width of about 2 feet and a battery to KDA volume ratio of about 80%, the KDA length would be about 10 feet. This would be a very practical keel configuration and keel weight for the proposed 34 foot sailboat.

(28) It is also useful to note that the KDA could be of the winged keel configuration, which is well known in the art to increase the draft while sailing, without increasing the draft while motoring. Furthermore, the winged keel could provide lift, by acting as a foil when the boat is operating under high power planning conditions, thereby improving performance, reducing power consumption and extending the high-power operating time.

(29) Some example calculations on the size of the battery pack for one preferred small motor boat embodiment, would be useful at this time. Assuming a 20-foot trailer-able motor boat with a total displacement of 6,000 pounds. To get such a boat quickly onto a plane would require about 120 horsepower (HP). Once again, assuming a conservative specific energy of the battery pack at 74 W-hr/kg, specific power of 185 W/kg and energy density of 185 W-hr/liter and an overall conversion efficiency of 80%, then approximately 10,000 pounds of batteries would be required to provide sufficient power to get the motor boat up on a plane for at least 3 hours. This would also provide a cruising time of 35 hours, with the motor producing about 10 Hp shaft power. These batteries would occupy about 64 cubic feet, so for a shallow draft design with a draft of about 1.3 feet, an average KDA width of about 6 feet and a battery to KDA volume ratio of 80%, the KDA length would be about 10 feet. This would be a very practical KDA configuration for the proposed 20-foot motor boat.

(30) While we have shown and described several implementations in accordance with the disclosure, it should be understood that the same is susceptible to further changes and modifications without departing from the scope of the disclosure. Therefore, we do not want to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.