Onboard high voltage battery charging system for outboard marine propulsion systems

Abstract

A heat transfer device including a reservoir, a pump fluidly coupled to the reservoir, and a splitter fluidly coupled to the pump and coupled to a plurality of fluid flows. The heat transfer device includes a first temperature sensor disposed between the pump and the splitter, and for each of the plurality of fluid flows, an adjustable valve, a motor fluidly coupled to the adjustable valve, a second temperature sensor integrated in the motor, and a third temperature sensor disposed after the motor. The heat transfer device includes a combiner fluidly coupled to each of the fluid flows, a fourth temperature sensor disposed after the combiner, and a heat sink fluidly coupled to the combiner and the reservoir, and the second temperature sensor is configured to provide a control signal to a control unit to control the fluid flow through the adjustable valve.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Applications Nos. 63 / 298504, 63 / 298521, 63 / 298498, 63 / 298511, and 63 / 298518, filed January 11, 2022. Each of these applications is incorporated herein by reference in its entirety.

[0002] The present disclosure is directed to marine propulsion systems and, more particularly, to a housing structure for power transfer with cooling, optimized heat transfer, lubrication, and battery charging for a marine propulsion system. [Background technology]

[0003] Marine propulsion engines have historically been categorized into three general types: inboard marine propulsion systems, outboard marine propulsion systems, and inboard / outboard marine propulsion systems.

[0004] An inboard propulsion system includes a prime mover that uses an energy source to convert energy into rotational motion of a shaft or shafts, and a transmission that transmits the rotational force to a propeller shaft that protrudes from the bottom of the boat. The propeller is fixed to the end of its underwater shaft and generates thrust that is directed by a rudder that is usually located aft of the propeller. An outboard motor generally includes a powerhead with a prime mover, a lower unit or gear case that houses the propeller and shaft, and a center section that allows a power transmission device to transmit power from the prime mover to the propeller shaft while providing a physical connection between the powerhead and the lower unit. The entire outboard motor is mounted on the transom of the boat and can be removed. An inboard / outboard motor system, also called an inboard / outboard or drive system, houses a prime mover inside the boat. The shaft of the prime mover is connected to an outdrive transmission that transmits power to the lower unit or gear case.

[0005] Inboard and outboard marine propulsion systems traditionally use a set of right angle bevel gears to transfer rotational power from the prime mover to the propeller. In the case of combustion engines, an additional set of gears is used to allow for reversal of rotation.

[0006] Various power transmission methods are known from the prior art, including belt or chain transmission arrangements. Synchronous belts have become strong and durable, allowing for potential use in higher power marine engine transmissions. Implementation of such belt technology presents challenges in physical housing arrangements and mechanical assembly. The frontal area and hydrodynamic shape of the submerged portions of the marine propulsion system can affect the drag and efficiency of the system. Applying belt drive technology in traditional physical architectures designed to accommodate rotating shafts and gears creates hurdles for an overall efficient design.

[0007] A by-product of power generation and power transmission is waste heat. Failure to adequately dissipate waste heat can lead to catastrophic failure, including but not limited to thermal runaway or system shutdown. Historically, thermal management systems for electric vehicles have been limited in capability, overly complex, or both. For example, early generation electric vehicles often used multiple independent thermal management subsystems. Such an approach is inherently inefficient because each thermal management subsystem requires its own components (e.g., pumps, valves, coolant systems, etc.). This has a direct impedance to the total system efficiency and therefore, in the case of electric vehicles, a range. Alternatively, a single loop with each component can be connected in series with each other. This method permanently prioritizes certain components regardless of their immediate need and increases the overall back pressure of the system, requiring additional power for the circulation pumps. Typically, propulsion systems utilize either closed-loop or open-loop systems. Open-loop systems take in fluid from an external body of water and circulate it around selected components to dissipate heat. Open-loop systems may include an internal closed-loop cooling circuit that uses a heat exchanger. Other propulsion systems utilize a fully closed loop cooling system. A closed loop system generally includes some number of waste heat generating components, at least one heat exchanger, a pump, valves, and a reservoir cooling water flow loop. Both open and closed loop systems have advantages and disadvantages.

[0008] Open systems are simpler because they transfer waste thermal energy directly from the components to the open-source cooling water loop. Disadvantages of open systems include that the intakes tend to be blocked when covered, allowing oil or other contaminants to easily enter the cooling water flow, thereby causing environmental impacts. Furthermore, the use of salt water for cooling can rapidly corrode sensitive components. Periodic flushing is therefore a common requirement. Advantages of closed loop systems include applicability to propulsion systems other than marine applications, such as automotive and aerospace. Other advantages include the ability to use certain working fluids. Disadvantages include limited ability to scale heat dissipation, as the heat sink must scale with waste heat generation. In comparison, open systems only require increased flow rates.

[0009] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure are intended to address these and other problems.

[0010] Gear reduction systems are common and essential in traction drives and other propulsion systems. They help match the torque / power curve of the prime mover to the speed requirements of the output shaft. For combustion and electric motors, the power output is limited while operating in the low RPM range of the system. Gear reduction then provides a higher torque for the same output torque. A common example is an automotive transmission, designed to allow the engine to operate at an efficient RPM while maintaining control of the output shaft.

[0011] An epicyclic gearbox or gearbox (also called a "gear set") generally converts a rotational input into either a slower rotating shaft with more torque or a faster rotating shaft with less torque. In some gearboxes, straight cut spur gears are used with involute teeth. Other gearing systems may use different tooth profiles or non-spur gears. Electric motors can achieve higher operating efficiency by rotating at higher RPM. Pairing with a gear reduction can achieve high efficiency of the motor while maintaining sufficient torque at low speeds. The reduction ratio is determined by the relative number of teeth of the current gears.

[0012] Gear reduction systems are common and essential in traction drives and other propulsion systems. They help match the torque / power curve of the prime mover to the speed requirements of the output shaft. For combustion and electric motors, the power output is limited while operating in the low RPM range of the system. Gear reduction then provides a higher torque for the same motor output torque. A common example is an automotive transmission, designed to allow the engine to operate at an efficient RPM while maintaining control of the output shaft.

[0013] An epicyclic gearbox comprises an outer ring gear, a central sun gear, small planet gears, and a planet carrier. The function of the gearbox is to convert the rotational input to a slower rotating shaft with more torque or a faster rotating shaft with less torque. Losses during power transmission are inevitable. Examples of losses are 1) rolling losses, 2) sliding losses, 3) glide losses, and 4) bearing losses. Reducing losses in the system increases the system efficiency of the drivetrain. Losses that occur typically take the form of waste heat. This waste heat must be sufficiently removed from the gearbox to prevent damage caused by overheating. Several solutions for gearbox cooling may use either 1) fan cooling (mounted on the high speed shaft to keep air flowing over the outer housing), 2) water cooling (mounted on the radial housing with a water jacket), or 3) oil-water cooling (uses a separate heat exchanger to transfer the waste heat from the gears to the oil to the water). These methods are progressively more effective, but each is more complicated than the previous.

[0014] The power transmitted by a shaft is proportional to the torque applied and the rotational speed (RPM). Epicyclic gear reductions have an upper power limit due to two main limiting factors. First, they limit the maximum torque and second, they limit the maximum rotational speed. Material properties have a limit on the torque that can be transmitted. If the torque limit is exceeded, the material will deform and break. This is most likely to occur at the gear or spline teeth where the load is the highest. Thermal loads limit the ability to increase the RPM indefinitely. Bearings are generally the first components to place a limit on the maximum RPM. If a bearing overheats, it can friction weld, burn the lubricant, reduce the oil volume, and / or reduce the lubrication capacity. Current solutions to these challenges include using complex heat treatment processes to increase the strength and therefore the torque capacity of the material. Other solutions include the use of advanced materials such as extremely heat resistant ceramics. This is used in applications such as gas turbine bearings where speeds can exceed 100,000 RPM and temperatures can reach 1000K. The excessively high cost of these solutions limits mass adoption. The typical method of cooling and lubricating a gear reducer is to submerge it in oil and circulate the oil through a radiator or heat sink, which is inefficient because it requires its own circulation system.

[0015] There are various power transmission methods, including drive shaft, belt, chain, or direct drive transmission arrangements. Inboard and outboard marine propulsion systems traditionally use a drive shaft with a set of right angle bevel gears to transmit rotational power from the prime mover to the propeller. In the case of combustion engines, an additional gear set is used to allow for reversal of rotation. A drive shaft with bevel gears at the bottom specifically encourages vertical power output from the powerhead and allows large engines to be centered above the lower unit. However, drive shafts also suffer from higher friction losses than other methods. Direct drive systems are common in many small power outboard systems where the motor is mounted in the lower unit and directly connected to the propeller. This is possible because the size of the electric motor is small compared to combustion engines, but the geometry of this engine presents a problem for larger and more powerful motors because the frontal area and hydrodynamic shape of the submerged motor causes large drag.

[0016] Synchronous belts have become strong and durable, allowing for potential use in higher power marine engine transmissions. Implementation of such belt technology presents challenges in physical housing arrangements and mechanical assembly. Two significant hurdles to overcome when using belt drives on outboard motors are the need to keep the belt under tension and the tendency of the belt to shift along the pulleys if the shafts are not properly aligned. Tension can be added to the belt by either physically moving the pulleys apart or by deflecting the belt at an idler pulley, thereby increasing the distance the belt must travel between pulleys. Tension is required on the belt to prevent it from slipping or skipping teeth when under load. The amount of tension required for the belt to function properly is proportional to the torque applied to the sprocket and the size of the sprocket. Despite the added friction, idler pulleys have thus far been ubiquitous for belt drives in marine propulsion applications due to the difficulty of moving either the propeller shaft or the prime mover and power head without sacrificing either shaft alignment or watertightness.

[0017] The primary losses in synchronous belts are due to friction between the belt and the sprockets, as well as friction in the bearings in which the prime mover and propeller shafts rotate. The tension in the belt adds large radial loads which increase the friction experienced by the drive train. This problem can be somewhat mitigated by using sprockets with a larger diameter and more teeth, but this is often impractical as it can lead to hydrodynamic losses.

[0018] A battery charger in a battery electric vehicle serves to take the alternating current (AC) power provided by the power grid and convert it to direct current (DC) power that can be stored in the battery. Although the power grid uses AC power to facilitate transmission, chemical batteries can only store DC power. A separate battery charger is used in situations where it is desirable to reduce the amount of equipment in an electric vehicle, or for high power applications where the size and cost of the charger makes it impractical to include in the electric vehicle.

[0019] A by-product of power generation, power conversion, and power transmission is waste heat. Failure to adequately dissipate waste heat can lead to catastrophic failure, including but not limited to thermal runaway or system shutdown. Historically, off-board thermal management systems for marine electric vehicles primarily serve to cool the motor and inverter found in the off-board engine. The battery and battery charger generally either have their own thermal management system or do not require active cooling. In one very common design, the battery charger is used as a separate component that is only connected to the marine propulsion system during use. This has the advantage that the charger can be left behind, reducing weight. The disadvantage is that the batteries cannot be charged without this additional equipment, which, when brought along, is heavier than its integrated counterpart. A detached battery charger needs to have its own thermal management system, since heat dissipation is often a major factor in how much power can be delivered to the batteries.

[0020] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure are intended to address these and other problems. Summary of the Invention

[0021] The objects and advantages of the presently disclosed subject matter will be set forth in and apparent from the following description and will be learned by practice of the presently disclosed subject matter. Additional advantages of the presently disclosed subject matter will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings.

[0022] To achieve these and other advantages, and in accordance with the objectives of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes a heat transfer device including a reservoir configured to contain a working fluid, a pump fluidly coupled to the reservoir, a splitter fluidly coupled to the pump and coupled to a plurality of fluid flows, a first temperature sensor disposed between the pump and the splitter, the first temperature sensor configured to measure a first temperature of the working fluid, for each of the plurality of fluid flows, an adjustable valve, a motor fluidly coupled to the adjustable valve, a second temperature sensor integrated with the motor, the second temperature sensor configured to measure a second temperature of the motor, a third temperature sensor disposed after the motor, the third temperature sensor configured to measure a third temperature of the working fluid, a combiner fluidly coupled to each of the plurality of fluid flows and configured to combine each of the plurality of fluid flows, a fourth temperature sensor disposed after the combiner, the fourth temperature sensor configured to measure a fourth temperature of the working fluid, and a heat sink fluidly coupled to the combiner and the reservoir. The second temperature sensor is configured to provide a control signal to the control unit to thereby control fluid flow through the adjustable valve.

[0023] In some embodiments, the heat transfer device is integrated into a marine propulsion system.

[0024] In some embodiments, the at least one motor is coupled to an inverter.

[0025] In some embodiments, the at least one motor is coupled to the charger.

[0026] In some embodiments, a fifth temperature sensor disposed behind the heat sink, the fifth temperature sensor configured to measure a fifth temperature of the working fluid. In some embodiments, the adjustable valve is a continuously adjustable valve. In some embodiments, the working fluid is a refrigerant. In some embodiments, the working fluid is a water-glycol mixture. In some embodiments, the splitter is a manifold. In some embodiments, the multiple outputs of the splitter are each coupled to an adjustable valve, each of the adjustable valves further comprising a flow sensor. In some embodiments, each of the adjustable valves is individually controlled.

[0027] To achieve these and other advantages and in accordance with the objects of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes a gearing system including a motor having a shaft extending from the motor to an exterior end terminal of the motor, a planetary gear set including a sun gear, two or more planetary gears coupled to a carrier, and a ring gear, the planetary gear set having a proximal side facing the motor and a distal side facing away from the motor, the sun gear being disposed on the distal side, and a housing enclosing the planetary gear set, the housing coupled to the ring gear. An axle extends at least partially through the housing and the planetary gear set, the shaft coupled to the sun gear, and when the shaft rotates at a first revolutions per minute (RPM), the housing rotates at a second RPM less than the first RPM.

[0028] In some embodiments, the gearing system further comprises a spacer disposed on the shaft and between the planetary gear set and the motor.

[0029] In some embodiments, the carrier is attached to the spacer.

[0030] In some embodiments, the ratio between the first RPM and the second RPM is two.

[0031] To achieve these and other advantages and in accordance with the objectives of the presently disclosed subject matter, as embodied and broadly described, the presently disclosed subject matter includes a system including a motor, an input shaft extending from the motor to a terminal end, a planetary gear set adjacent to and in contact with a reservoir, the planetary gear set including a sun gear, two or more planetary gears coupled to a carrier, a ring gear, and an output shaft, the input shaft is coupled to the sun gear, the output shaft is coupled to the carrier, and a reservoir disposed between the motor and the planetary gear set, the reservoir having a toroidal shape about the input shaft and being fluidly isolated from the shaft and the planetary gear set.

[0032] To achieve these and other advantages, and in accordance with the objects of the presently disclosed subject matter, as embodied and broadly described, the presently disclosed subject matter provides a belt assembly comprising a first drive shaft, a lifting plate fixed relative to the first drive shaft, a central upper collar, a first strut extending from a proximal end to a distal end, and a second strut extending from a proximal end to a distal end, each of the first strut and the second strut having an internal belt gap, the first strut being aligned with the second strut, a first strut spaced from a second strut, proximal ends of the first and second struts coupled to a central upper collar; a lower unit coupled to distal ends of the first and second struts, the lower unit having a second drive shaft, the central upper collar being fixed relative to the second drive shaft; a belt rotatably coupling the first drive shaft to the second drive shaft, a first portion of the belt being disposed within an internal belt gap of the first strut and a second portion of the belt being disposed within an internal belt gap of the second strut; and one or more lifting screws coupling a lifting plate to the central upper collar, wherein adjusting the one or more lifting screws changes a distance between the lifting plate and the central upper collar to thereby adjust tension in the belt; and an actuator disposed on each of the one or more lifting screws.

[0033] In some embodiments, the marine propulsion system further includes a lifting platform disposed between the lifting plate and the center upper collar, and a load cell in contact with the lifting plate and the lifting platform.

[0034] To achieve these and other advantages, and in accordance with the objectives of the presently disclosed subject matter, as embodied and broadly described, the presently disclosed subject matter includes a system further including an electric boat motor, a lower unit coupled to the electric boat motor, the lower unit including a propeller, an inverter, an onboard battery charger coupled to the inverter and one or more high voltage batteries, and a heat transfer circuit including a reservoir having a working fluid, a pump, a valve, a first tube fluidly coupling the reservoir to the pump, a second tube fluidly coupling the pump to the valve, a third tube fluidly coupling the valve to the inverter, a fourth tube fluidly coupling the valve to the onboard battery charger, a fifth tube fluidly coupling the inverter to the motor, a sixth tube fluidly coupling the onboard battery charger to the sixth tube, a seventh tube fluidly coupling the onboard battery charger to the sixth tube, and an eighth tube fluidly coupling the lower unit to the reservoir. When in the charging configuration, the valve allows hydraulic fluid to flow through the fourth tube to the onboard battery charger, and when in the operating configuration, the valve does not allow hydraulic fluid to flow through the fourth tube.

[0035] To achieve these and other advantages, and in accordance with the objectives of the presently disclosed subject matter, as embodied and broadly described, the presently disclosed subject matter includes a method of recharging an electric boat, the method including providing an electric boat having a hull, an outboard motor coupled to the hull, and one or more rechargeable batteries disposed within the hull, the outboard motor including an electric motor and an onboard battery charger, and coupling the onboard battery charger to an alternating current source to thereby charge the one or more rechargeable batteries. [Brief description of the drawings]

[0036] [Figure 1] 1 illustrates an isometric view of an outboard motor according to an embodiment of the present disclosure. [Diagram 2]FIG. 2 is a block diagram representing component level interactions between the overall propulsion system and the dual strut lower unit in accordance with an embodiment of the present disclosure. [Diagram 3] FIG. 2 illustrates a partial side view of a dual strut and lower unit bullet architecture taken generally below line 1-1 of FIG. 1 in accordance with an embodiment of the present disclosure. [Figure 4] 1 illustrates a partial front view taken generally below line 1-1 of FIG. 1, in accordance with an embodiment of the present disclosure. [Diagram 5] 3 illustrates a cross-sectional side view taken generally below line 3-1 of FIG. 3, in accordance with an embodiment of the present disclosure. [Figure 6] 3 illustrates a cross-sectional top view taken generally below line 3-1 of FIG. 3, according to an embodiment of the present disclosure. [Figure 7] 3 illustrates a cross-sectional front view taken generally below line 3-1 of FIG. 3, in accordance with an embodiment of the present disclosure. [Figure 8] FIG. 1 illustrates a schematic diagram of an outboard power transmission system according to an embodiment of the present disclosure. [Figure 9] 1 illustrates a schematic diagram of a belt drive transmission system according to an embodiment of the present disclosure. [Figure 10A] 14 illustrates a dual strut and a single strut computational fluid dynamics visualization according to an embodiment of the present disclosure. [Figure 10B] 14 illustrates a dual strut and a single strut computational fluid dynamics visualization according to an embodiment of the present disclosure. [Figure 11] 1 illustrates a graphical representation of initial computational fluid dynamics drag results for a dual strut (left) compared to a single strut (right), in accordance with an embodiment of the present disclosure. [Figure 12] 1 illustrates a diagram of a cooling loop system having three heat-generating components in parallel, according to one embodiment of the present disclosure. [Figure 13] 1 illustrates a diagram of a cooling loop system operating to cool a high temperature charger in charging mode, according to one embodiment of the present disclosure. [Figure 14]1 illustrates a diagram of a cooling loop system that operates to cool a high temperature motor and inverter and bypasses the charger in accordance with one embodiment of the present disclosure. [Figure 15] 1 illustrates a cross-sectional view of a planetary gear set having a 3:1 gear ratio when constraining the ring gear according to one embodiment of the present disclosure. [Figure 16] 1 illustrates a cross-sectional view of a gearbox and motor according to one embodiment of the present disclosure. [Figure 17] 1 illustrates an isolated, exploded, half-sectional view of a planetary gear set and spacer according to one embodiment of the present disclosure. [Figure 18] 1 illustrates an isometric half-section view of a gear reduction assembly with an input motor and spacers removed for clarity, according to one embodiment of the present disclosure. [Figure 19] 1 illustrates a planetary gearbox according to one embodiment of the present disclosure. [Figure 20A] 2 illustrates a motor having a shaft with a spacer coupled to the exterior of the motor 200, according to one embodiment of the present disclosure. [Figure 20B] 1 illustrates a planetary gear set, spacer, and motor according to one embodiment of the present disclosure. [Figure 21A] 1 illustrates a cross-sectional view of a planetary gear set, a spacer, and a motor according to one embodiment of the present disclosure. [Figure 21B] 1 illustrates a cross-sectional view of a gearset housing and a motor coupled to a carrier according to one embodiment of the present disclosure. [Figure 22A] 1 illustrates a cross-sectional view of a planetary gear set according to one embodiment of the present disclosure. [Figure 22B] 1 illustrates a cross-sectional view of a planetary gear set and a gear set spacer according to one embodiment of the present disclosure. [Diagram 23] 1 illustrates a gearbox housing with output splines highlighted according to one embodiment of the present disclosure. [Figure 24] 1 illustrates a planetary gearbox according to one embodiment of the present disclosure. [Diagram 25] 1 illustrates a cross-sectional view of a gearbox and motor according to one embodiment of the present disclosure. [Figure 26] FIG. 1 illustrates an isometric cross-sectional view of a gearbox with input and output shafts hidden for clarity, according to one embodiment of the present disclosure. [Figure 27] 1 illustrates a side view including a tensioning mechanism, a power head, a portion of a center section, a belt, and a propeller shaft according to one embodiment of the present disclosure. [Figure 28A] 1 illustrates a top view of a power head and center upper collar with the power electronics removed, according to one embodiment of the present disclosure. [Figure 28B] 1 illustrates a cross-sectional view of a belt and a motor shaft according to one embodiment of the present disclosure. [Figure 29] 1 illustrates a close-up view of a pull screw with a sensor and actuator according to one embodiment of the present disclosure. [Diagram 30] 1 illustrates an isometric view of an outboard motor with various components removed to illustrate a cooling loop according to one embodiment of the present disclosure. [Diagram 31] 1 illustrates an isometric view of an outboard motor drive head with various components removed to illustrate a cooling loop according to one embodiment of the present disclosure. [Diagram 32] 1 illustrates an isometric view of an outboard motor and boat with an onboard battery charger (OBC) and a highlighted high voltage battery, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] An outboard motor powertrain generally includes a prime mover, such as a combustion engine or electric motor, a vertical drive shaft, a bevel gear, a clutch, and a propeller shaft (to which the propeller is attached). The bevel gear is a gear between two intersecting shafts, where the gear tooth contact surface is conical in shape. The bevel gear may provide greater efficiency than other gear options and allow for gear reduction between the intersecting shafts. A clutch is used to allow the prime mover to operate in a single direction, but may also allow the propeller shaft to rotate in both clockwise and counterclockwise directions. In various embodiments, the outboard motor may use a dog clutch to switch between forward, neutral, and reverse. This requires engagement and disengagement of shift gears, leading to premature wear of the gear teeth. To minimize this wear, the entire assembly may be submerged in oil or lubricant, which may be harmful to the environment and difficult to dispose of. Dissipating heat from major components, including but not limited to the prime mover, gears, and bearings, may be essential to reliable operation of this type of outboard motor. Outboard motors can take in fluid (e.g., seawater) from a body of fluid (e.g., the ocean), where they operate to circulate the fluid around the system and cool the components. However, this external fluid intake can introduce contaminants, including, but not limited to, salt, sand, and / or mud, which can accelerate wear and corrosion processes. In some embodiments, the prime mover can be housed in a lower unit below the water line. This configuration offers the advantage of simplicity, but can limit heat transfer capabilities. In various embodiments, other means of power transmission instead of vertical drive shafts and bevel gears include, for example, chain drive and belt drive systems. In various embodiments, synchronous belts can be strong and durable, allowing for potential use in higher power marine engine transmissions. In various embodiments, the implementation of such belt or chain technology can present challenges in physical housing arrangements and mechanical assembly, as the frontal area and hydrodynamic shape of the submerged portion of a marine propulsion system greatly affect the drag and efficiency of the system.

[0038] Therefore, there is a need for a marine propulsion system that is optimized for belt and chain drive motors while reducing drag (e.g., improving hydrodynamics) and improving heat dissipation. SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure are intended to address the above challenges and others.

[0039] In various embodiments, an inboard / outboard marine propulsion system includes a prime mover that transmits power to a driven shaft through a synchronous belt, an anti-ventilation plate, a lower unit housing, one or more skegs extending from a bottom of the lower unit housing, and a set of struts (e.g., two struts) that connect the lower unit housing to the anti-ventilation plate and attachment points on the cowling (and / or frame structure within the cowling). In various embodiments, the set of struts may be substantially aligned (e.g., parallel) with one another. In various embodiments, each strut may include one or more (e.g., a plurality) of removably attachable, modular trailing edge pieces. In various embodiments, the removably attachable trailing edge pieces may allow fine tuning of hydrodynamic characteristics.

[0040] In various embodiments, the attachment points connect the center section to the lower unit and prime mover in outboard marine propulsion system embodiments, or to the lower unit and outdrive in the case of inboard-outboard marine propulsion systems. In various embodiments, certain variable parts of the system allow for lower drag, higher performance, and efficient adaptation of belt drive technology. In various embodiments, the components of the marine propulsion system may be constructed to be modular, replaceable, and / or have integrated cooling channels. In various embodiments, the integration of heat dissipation functionality into a multi-strut (e.g., dual strut) architecture may provide increased surface area from the multiple struts to optimize heat transfer capabilities. In various embodiments, multiple struts (e.g., two struts) increase the surface area of ​​the struts in contact with the water, thereby improving heat transfer (e.g., conduction) with the water (similar to fin heat transfer). One skilled in the art will appreciate that there are configurations of struts in a set that may be utilized for this purpose. For example, two, four, six, or eight strut configurations. In various embodiments, there may be struts that are dedicated to structure and struts that operate to house one or more belts or chains to drive a motor.

[0041] In various embodiments, the frontal area and hydrodynamic shape of the submerged portions of the marine propulsion system may affect the drag and efficiency of the system. Reducing drag on a marine propulsion system has a direct improvement to the net efficiency of the system. In various embodiments, because the set of struts may be submerged during use, the set of struts may have any suitable hydrodynamic shape to reduce and / or optimize drag. For example, each strut may include an airfoil shape with the leading edge of the airfoil corresponding to the front side of the strut. In various embodiments, the struts may be hydrodynamically optimized, such as a hull shape or teardrop shape in cross section or section.

[0042] In operation, the belt has a tight side and a slack side. In various embodiments, the belt may be isolated (i.e., sealed) from the surrounding body of water in which the motor operates. In various embodiments, both sides of the belt may be supported to provide tension to the belt. In various embodiments, providing tension to the belt may reduce (e.g., stop) contamination from the surrounding water. In various embodiments, the marine propulsion system may include, among other things, a continuous loop power transmission device. For example, a prime mover may be mechanically (e.g., rotationally) coupled to a propeller via a belt or chain. The continuous loop power transmission device may include one or more belts or chains, alone or in combination, to transmit power through the system. The belts and / or chains may be selectively or actively slack controlled, such as to maintain efficiency.

[0043] In various embodiments, each strut may be positioned at a predetermined distance from one another, thereby allowing fluid flow between the struts. For example, in a dual strut arrangement, in various embodiments, the struts may be positioned from about 2 to about 24 inches from one another. In various embodiments, the struts may be positioned from about 1.5 to 6 inches from one another. In various embodiments, in larger applications (e.g., yachts, tugboats, etc.), the struts may be positioned several feet apart. In various embodiments, the struts may be positioned up to about 12 feet apart. In various embodiments, the spacing of the struts may depend on one or more performance factors, such as, for example, (1) the hydrodynamic interaction between the struts and / or (2) the hydrodynamic drag of the lower unit. In various embodiments, the struts may be spaced horizontally. In various embodiments, the struts may be spaced or offset both horizontally and longitudinally (i.e., in the direction of motor travel). In various embodiments, the struts may be of various sizes and shapes such that sets of struts contain different hydrodynamics between the sets. In various embodiments, the shape of a strut may vary along its vertical length, such that the cross-sectional shape of the strut varies according to depth or vertical position on the strut. In various embodiments, the wider the strut, the less fluid interaction between multiple struts (interference). In various embodiments, wider struts may improve certain performance factors. In various embodiments, the size of the lower unit (e.g., drag area) may be minimized, thereby minimizing drag. In various embodiments, the size of the lower unit may be minimized by providing a small frontal area of ​​the lower unit. In various embodiments, the size of the lower unit may be proportional to the size of the strut. For example, for wider struts, a larger lower unit may be provided. In various embodiments, the struts may not be parallel. For example, the struts may be non-linear or may be arranged at an angle (e.g., a "V" shape) relative to the horizontal (horizontal plane).

[0044] In various embodiments, each strut may include a vertical strut cross-sectional profile that minimizes drag through the water. In various embodiments, the cross-sectional profile may reduce (e.g., minimize) the drag area while allowing sufficient void space to accommodate a continuous loop (e.g., a belt or chain). In various embodiments, each strut may include an airfoil shape. In various embodiments, any strut (e.g., some or all struts) may have a substantially uniform shape along its length. In various embodiments, any strut (e.g., some or all struts) may have a shape that varies along its respective length. For example, the struts may taper from a wider wing (having a higher drag area) to a thinner wing (having a lower drag area) or vice versa from the leading edge to the trailing edge. In various embodiments, any strut (e.g., some or all struts) may have a substantially uniform width along the length of the strut (in the direction of flow). For example, an airfoil shape may have a substantially similar (e.g., equal) chord length and / or camber curve along the entire length of the strut. In various embodiments, any strut (e.g., some or all struts) may have a width that varies along the length of the strut (in the direction of flow). For example, an airfoil may have a chord length and / or camber curve that varies along the entire length of the strut. The struts may have a mirror image shape that is symmetric about a central axis passing through the strut, or alternatively, each strut may be formed with a unique shape / profile relative to adjacent struts. In various embodiments, the struts may include internal structural features such as beams or webbing. In various embodiments, the struts may be additively manufactured (e.g., 3D printed). In various embodiments, the struts may be machined from metal stock. In various embodiments, the struts may be cast, molded, or formed from a composite or another material.

[0045] In various embodiments, each strut may include a separate void space configured to accommodate each side of the continuous loop (i.e., a slack side and a tight side). In various embodiments, the separate void spaces within either one or all of the vertical struts may be configured to transfer fluid (e.g., a heat transfer fluid) throughout the outboard motor.

[0046] In various embodiments, one or more of the struts may include a split line, thereby separating the strut into two or more pieces. In various embodiments, the split line allows for ease of access so that a continuous loop (e.g., a chain or belt) may be installed or removed during or after manufacture (e.g., for repair). The split line(s) may extend along an entire portion of the strut (e.g., between the nose cone and the anti-ventilation plate).

[0047] FIG. 1 illustrates an isometric view of an outboard marine propulsion system 100. In various embodiments, the marine propulsion system 100 (e.g., an outboard motor) may include a powerhead section, a prime mover cowling, a belt drive, an anti-ventilation plate, a dual strut transmission housing, a lower unit having a propeller, and a skeg. In various embodiments, the outboard marine propulsion system 100 includes a mounting 101 configured to releasably couple a boat's transom to an outboard midsection 102 via a transom mounting pad 103. In various embodiments, the outboard motor is mounted to a steering bracket 104 and may be steered through various methods, including but not limited to cables, pulleys, hydraulic and / or electromechanical actuators that rotate the outboard motor about the axis of a steering tube 105. In various embodiments, the angle of the outboard motor, and therefore also the propulsion angle, may be controlled about a tilt axis 106. In various embodiments, the prime mover components, whether electrically or liquid fuel powered, are located below an upper cowling 107. In various embodiments, the side of the cowling 107 that faces the transom of the boat may include a faceplate 108. In various embodiments, the prime mover drive shaft is connected to a propeller shaft 109 via a synchronous drive belt (not shown). In various embodiments, the synchronous drive belt in turn drives a propeller 110 to generate momentum for propelling the boat to which the marine propulsion system 100 is attached. In other embodiments, the propeller may be replaced by an impeller, water jet, or other propulsion device. In this embodiment, the propeller tail cone 111 and tail fairing 112 match the geometric profile of the propeller to minimize turbulent losses and maximize efficiency. In other embodiments, the shape of the propeller tail cone 111 and tail fairing 112 may be adjusted to fit different propellers. A sprocket (located in the lower unit) is concentrically mounted to the propeller shaft 109 and housed within the lower unit 114. In various embodiments, the lower unit 114 may include a nose cone 115 at its tip portion.The one or more struts 116 provide an open path for the belt to transfer power from a sprocket attached to the prime mover under the upper cowling 107 to a sprocket on the propeller shaft 109. A separate strut 116 body allows the belt to operate without additional rolling components, allowing for the highest possible efficiency. The one or more struts 116 are spaced apart so that the belt does not have to be guided around obstacles or shapes as required by the prior art. The strut body has a hydrodynamic strut leading edge 117 and strut trailing edge 118 that reduces drag on the propeller 110 and maximizes laminar flow. The struts 116 connect to an anti-ventilation plate 120 that is fastened to a center bottom collar 121, which is in turn fastened to the center bottom. In various embodiments, a center top collar 122 may provide an interface between the center 102 and the upper cowling 107. In various embodiments, one or more skegs 124 are located under the lower unit. In various embodiments in which two or more skegs are provided, each skeg may be positioned equally spaced about the lower unit 114 and located upstream of the propeller.

[0048] FIG. 2 illustrates a block diagram 200 representing component level interactions between the entire propulsion system and the dual strut lower unit. The component blocks are generally located either onboard or outboard and are mechanically or electrically connected as indicated by the legend. In various embodiments, the operator controls the system via the control rudder, which interfaces with the energy storage system using onboard communication signals and with the outboard power electronics using additional communication cables. Communication protocols can be used including but not limited to serial, CAN bus, SPI, analog, and digital. In various embodiments, the energy storage system is connected to the power electronics block via a DC bus. In various embodiments, the DC bus can range from 12V to over 900V. In various embodiments, the power electronics block generally encompasses all power stages and control components required to use a DC voltage to drive the prime mover. In various embodiments, based on a signal from the control rudder, the power electronics can draw energy from the energy storage system through the DC bus and control the prime mover. In various embodiments, the prime mover can be an electric motor through phase power and feedback signals. In various embodiments, the prime mover is mechanically coupled through a drive shaft to a synchronous belt that rotates a driven shaft located in the lower unit, thereby powering the propeller.

[0049] FIG. 3 illustrates a partial side view of the dual strut and lower unit bullet architecture taken generally below line 1-1 of FIG. 1. Line 1-1 is the water line of an outboard motor boat in operation in some embodiments. During operation, all components below water line 1-1 are submerged and contribute to the hydrodynamic drag of the system. As explained in the background, inboard and outboard marine propulsion systems may use a single strut housing that connects the gear case to the powerhead. Additionally, nearly all combustion outboard motors use a shaft and bevel gear system to transmit power from the combustion or electric powerhead to the propeller. In that type of lower unit, a mechanical mechanism is required to switch from forward to neutral to reverse. This type of power transmission requires consistent maintenance to lubricate the gears and wears fast due to shifting at non-zero rotational speeds, which can result in a 15% efficiency loss. The bevel gears also generate significant noise.

[0050] Recent advances in materials technology have allowed for the development of more robust synchronous belt drives with the potential for increased efficiency, reduced noise, reduced maintenance, and lower costs. The present disclosure enables the use of synchronous belts in marine propulsion systems through a multi-strut body arrangement where each side of the belt runs through a different strut. Additionally, the present disclosure also provides a method for using electronic reversal from an electric prime mover, thereby eliminating the need for complex mechanical shifting solutions.

[0051] In various embodiments, the multi-strut design minimizes the disruption of fluid flow to the propeller during movement. In various embodiments, the multi-strut (e.g., dual strut) design reduces drag inducing frontal area (i.e., drag area) while increasing overall system robustness. In various embodiments, the strut 116 and anti-ventilation plate 120 interfaces are integrally formed. In various embodiments, the strut 116 and anti-ventilation plate 120 interfaces are mechanically fastened (e.g., with bolts and nuts). In various embodiments, the bottom of the strut can be integrally formed with the lower unit 114. In various embodiments, the lower unit 114 can be bullet shaped (bullet + bullet casing). In various embodiments, the first portion (e.g., tight side) and second portion (e.g., slack side) of the synchronous belt 130 are protected from water and / or external fluids in void spaces within the first and second struts 116. Thus, the belt 130 extends (vertically in operation) through the first strut 116 and into the lower unit 114 where it engages and drives the propeller 110 (forward / reverse), then extends up through the second strut 116 and back into the cowling 107.

[0052] In various embodiments, drag may be reduced through a hydrodynamic shape applied to the leading edge 117 and trailing edge 118 of the struts 116. In various embodiments, a convex surface on the sides of the struts 116 between the leading edge 117 and trailing edge 118 reduces form drag and wave generation. In various embodiments, the profile of the convex surface need not be symmetrical between struts and may be altered for different applications (i.e., not all struts need to be the same shape). In various embodiments, the struts 116 may be mirror images of each other (e.g., a first strut may be a mirror image of a second strut). In various embodiments, the sides of the struts 116 may be substantially parallel and of equal length. In various embodiments, the struts may be non-parallel. In various embodiments, the space between the struts may increase or decrease over the height of the struts.

[0053] In various embodiments, the sides of the struts 116 may not have a concave surface. In various embodiments, the leading edge 117 may be integrally formed with the struts 116. In various embodiments, the leading edge 117 may be manufactured separately and removably fastened to the struts 116. In various embodiments, the trailing edge 118 may be integrally formed with the struts 116. In various embodiments, the trailing edge 118 may be manufactured separately and removably fastened to the struts 116, for example, via strut attachment points (e.g., with screws, bolts, etc.). In various embodiments, the leading edge 117 and / or the trailing edge 118 may be modular and interchangeable for performance optimization. Additionally or alternatively, the strut(s) may include an access panel to allow for repair and inspection of the belt. The access panel may be spaced from the leading / trailing edges and may be located within a generally planar section of the strut(s).

[0054] In various embodiments, the strut(s) may include active control of the leading and / or trailing edge contours during operation. For example, electronic control (e.g., real-time or manual) may change the camber or chord length of the airfoil. In another example, electronic control (e.g., real-time or manual) may change the width (e.g., drag area) of the airfoil so that a continuous loop (e.g., belt) has enough room to operate within the void space.

[0055] Further aiding in hydrodynamic drag reduction and increased propulsive efficiency is the overall shape of the architecture. In various embodiments, the incoming fluid flow first interacts with the nosecone 115. In various embodiments, the geometry of the nosecone 115 may be designed with a smooth transition from the nosecone 115 across the nosecone / lower unit interface to the lower unit 114. In various embodiments, the nosecone 115 is removable and replaceable. In various embodiments, the nosecone 115 may include any suitable shape. For example, the nosecone 115 may include a bullet-like shape with blunt angles. In various embodiments, the central portion 113 of the lower unit 114 may have a substantially cylindrical shape (e.g., a bullet casing shape). In another example, the nosecone 115 may be substantially conical with a sharper tip. In various embodiments, as fluid flow passes through the lower unit 114, boundary layer separation can cause turbulence, thus increasing pressure drag on the propulsion system 100, so the tail fairing 112 can minimize loss-inducing boundary layer separation on the tail fairing / lower unit interface. In various embodiments, the tail fairing 112 is shaped such that the tail fairing / propeller hub interface hydrodynamically mates with the propeller hub to optimize flow into the propeller. Thus, the struts 116, lower unit 114, nose cone 115, and tail fairing 112 can be configured in a virtually seamless design with no abrupt changes in size / shape / diameter, and the assembly of these components forms a continuous exterior surface area to minimize drag.

[0056] In various embodiments, the tail fairing may be a frusto-conical shape that tapers from a larger diameter at the center section 113 to a smaller diameter at the propeller 110. In various embodiments, as the propeller 110 spins and creates areas of high and low pressure, flow is directed across the propeller tail cone 111, reducing turbulence and thus further minimizing drag on the propulsion system 100. In a typical combustion-type marine engine, the engine exhaust is generally directed down through a single section and out through the center of the propeller. The present disclosure eliminates this style of exhaust and allows for a more efficient overall hydrodynamic approach.

[0057] In various embodiments, one or more skegs 124 may be attached to the central portion 113 of the lower unit 114. In various embodiments, the central portion 113 may include one or more skeg attachment points configured to allow for the attachment of one or more skegs 124. In various embodiments, the skeg 124 may have a generally fin-like shape. In various embodiments, the skeg 124 may have a constant thickness along its length. In various embodiments, the skeg 124 may have a depth that varies along its length. For example, the skeg 124 may taper from a first, greater depth d1 to a second, lesser depth d2. In various embodiments, one side of the skeg 124 may be vertical while the other side may be tapered. In various embodiments, both sides of the skeg 124 may be tapered. In various embodiments, the skeg 124 may have a curved or airfoil shape, similar to the struts 116. In various embodiments, the skeg 124 is removable and replaceable at the skeg / lower unit interface. In various embodiments, the skeg 124 may be integrally formed at the skeg / lower unit interface. In various embodiments, the skeg 124 contributes to stability and hydrodynamic flow interactions by having a trailing edge that minimizes turbulence in the flow entering the propeller 110. In various embodiments, the bottom edge of the skeg 124 may be lower than the blades of the propeller 110, providing protection for the propeller 110 from impact with physical objects. Additionally or alternatively, the location of the skeg 124 may be adjusted upstream / downstream relative to the lower unit 114.

[0058] FIG. 4 illustrates a partial front view taken generally below line 1-1 in FIG. 1. As shown in FIG. 4, the prime mover 128 is rotatably coupled to the belt 130 via a drive shaft (not shown). As the prime mover rotates, either the left side 130a of the belt 130 or the ride side 130b of the belt 130 can transmit rotational force to or from the propeller. In the example shown, when the belt 130 is rotating counterclockwise (from the perspective of the prime mover 128), the left side 130a of the belt 130 is the slack side and the right side 130b of the belt 130 is the tight (i.e., tension) side. In various embodiments, the width of the gap between the two struts 116 (measured by the distance between the inner edges of each strut) can be altered to accommodate larger or smaller overall component dimensions while allowing the passage of fluid (e.g., seawater) and keeping the ride side 130b of the belt 130 and the left side 130a of the belt 130 parallel to one another. In various embodiments, the distance d between the inner edges of the struts 116 gap can be varied based on an ideal performance metric, for example to reduce the frontal (drag) area. In various embodiments, the distance d between the outer edges outer The thickness of the strut / lower unit interface may also vary, for example, to accommodate a thicker gradient belt. In various embodiments, the strut / lower unit interface may have a gentle hydrodynamic shape to minimize flow disturbance as water passes through the struts 116 to the propeller 110. In various embodiments, the propeller 110 may be located in front of the struts 116. In various embodiments, an anti-ventilation plate 120 may connect to the top (i.e., proximal end) of the struts 116 and may prevent the propeller from sucking air from the surface. The anti-ventilation plate may be colloquially referred to as a "cavitation plate." The top ends of the struts 116 may connect directly to the cowling 107, or additionally or alternatively, the top ends of the struts 116 may connect to a mounting plate / frame that receives the cowling 107.

[0059] FIG. 5 illustrates a partial side view, partially in section, taken generally below line 3-1 of FIG. 3. In various embodiments, the sprocket 126 is concentrically secured to the propeller shaft 119, which exits the lower unit bullet through the tail fairing 112. In various embodiments, the inside of the lower unit 114 is protected from seawater through seals on all edges and boundaries, including a set of shaft seals. In various embodiments, both leading edges 117 of the struts 116 include cooling water passages 117a to allow cooling water to flow therethrough. In various embodiments, cooling water can enter each strut through a cooling water port and then flow through the cooling water passages 117a, which removes heat from the cooling water through conduction. Thus, the present disclosure provides a closed circuit fluid cooling system, where the cooling water circulation path is maintained within the struts 116, the nose cone 115, and the anti-ventilation plate 120. Thus, the cooling water system does not need to rely on the intake of ambient water during operation. In various embodiments, the cooling water passage(s) 117a in each strut allows cooling water to enter the nosecone cavity 115a, which acts as a flooded, heat rejection reservoir. In various embodiments, the nosecone cavity 115a includes one or more nosecone turbulators 115b (e.g., undulating structures / walls / strips) configured to increase the turbulence of the heat transfer fluid and thus increase the heat rejection capacity. Optionally, the cooling water passages 117a may extend entirely through the anti-ventilation plate 120.

[0060] In various embodiments, the cooling water can flow bidirectionally through the struts 116 and through the cooling water passages 117a to the thermal circuit 140. In various embodiments, the cooling water passages 117a can include tubing, hoses, pipes, and / or other fluid transmission methods. In various embodiments, the thermal circuit can include electronic controllers pumps and / or heat generating components, including but not limited to power electronics and prime movers. In various embodiments, a set of cooling water port seals ensures that the heat transfer fluid is not contaminated. In various embodiments, additional voids can be provided in the trailing edge(s) 118, the belt storage void 131, the tail fairing 112, and / or the lower unit 114 and can be used for additional cooling water passages. In various embodiments, the longitudinal width of the belt storage void 131 can be varied to accommodate different size belts. In various embodiments, the trailing edge 118 can be mechanically fastened by a set of trailing edge fasteners 118a configured to fasten to a fastening panel 118b (e.g., a T-block). In various embodiments, this attachment method allows the trailing edge 118 to be separated from the struts 116 for installation and removal of the belt 130. In various embodiments, the belt storage gap 131 may be optimized such that the size of the gap (e.g., width of the gap space) is minimized. In various embodiments, less gap space may be better from a hydrodynamic standpoint (e.g., less drag area). In various embodiments, the belt storage gap 131 may be about 1 / 8 inch on either side of the belt 130. In various embodiments, the sprocket gap 125 may have a similar 1 / 8 inch gap. In various embodiments, the sprocket gap 125 may be smaller than the space between the belt 130 and the inside of the belt storage gap 131 because the belt may not have as much movement around the sprocket 126. In various embodiments, the belt storage gap 131 may include a spacing (e.g., width) of about 0.01 inch to about 0.25 inch on either side of the belt. For example, 0.25 inches on each side of the belt 130 provides an overall width of the belt receiving cavity 131 of 0.25 inches + 0.25 inches + belt thickness (inches).In various embodiments, the belt receiving gap 131 can include a spacing (e.g., width) of about 0.01 inches to about 6 inches on either side of the belt. In various embodiments, the spacing can correspond to the system size. In various embodiments, the spacing (e.g., width) can be about 12 inches on either side of the belt.

[0061] FIG. 6 illustrates a partial top view, partially in section, taken generally below line 3-1 of FIG. 3. In various embodiments, the nosecone 115 has an exterior contour that maintains attached flow with the surrounding fluid mass (e.g., reduces / prevents boundary layer separation). In various embodiments, the nosecone 115 has a conical shape. In various embodiments, the nosecone 115 may be blunt or rounded. In various embodiments, the contour may be changed to suit different operating conditions. In various embodiments, the lower unit 114 may be cylindrical in shape and connected to both struts. In various embodiments, the trailing edge 118 may be connected to the strut 116 through fasteners secured to the T-block 118b. The T-block is then held by the walls of the dual strut body. In various embodiments, the leading edge 117 may include a cooling water passage 117a having a circular diameter. In various embodiments, the cooling water passage 117a may have a substantially constant diameter throughout the thermal circuit 140.

[0062] FIG. 7 illustrates a partial front view, partially in section, taken generally below line 3-1 of FIG. 3. As shown in FIG. 7, the lower unit 114 and struts 116 include a belt receiving cavity through which the belt 130 may pass. In various embodiments, the struts 116 include a strut inner wall and a strut outer wall. In various embodiments, the strut inner wall and the strut outer wall may be made of any suitable material and may be integrally formed with the remainder of the strut body, but are not required. In various embodiments, the thickness of the strut wall may be selected based on the application to either increase stiffness or reduce drag. In various embodiments, within the lower unit 114, the belt drive sprocket 126 is concentric with the propeller shaft 119. In various embodiments, a keyway 127 is used to transmit torque between the sprocket 126 and the propeller shaft 119. In various embodiments, splines may be used or the sprocket 126 and the propeller shaft 119 may be integrally formed. In various embodiments, an air-filled sprocket gap 125 exists within the lower unit 114 to accommodate the thickness of the belt 130. In various embodiments, due to the dual strut configuration, the belt 130 can rotate about the sprocket 126 without physically contacting any other part of the lower unit 114. In various embodiments, this non-contact operation allows for lubrication-free operation compared to other motors that require the belt or transmission components to operate in an oil-filled bath. The belt 130 can wrap around the sprocket 126 with engagement between the respective surfaces over approximately 180 degrees of rotation of the sprocket. The sprocket 126 can include raised teeth, as shown, to increase frictional engagement with the belt and generate more torque.

[0063] FIG. 8 illustrates a schematic of a conventional outboard power transmission system. In various embodiments, it utilizes a prime mover 807 with a vertically extending drive shaft 808. In various embodiments, power is transferred from the vertical drive shaft and the horizontal prop shaft using gears. In various embodiments, a pinion gear 809 is used in conjunction with crown gears 811 and 813 to transfer rotational speed to the driven shaft. In many embodiments, a clutch is used with a sliding collar 812 that can engage with either the clockwise or counterclockwise crown gear. In various embodiments, this mechanism allows for a change in the direction of rotation of the prop shaft while maintaining the drive direction of the prime mover.

[0064] 9 illustrates a schematic diagram of a belt drive transmission system. In various embodiments, this is a schematic diagram of a specific embodiment of an alternative means of power transmission between a prime mover 901 and a lower driven shaft 905. In various embodiments, the prime mover utilizes a horizontally extending drive shaft 903 supporting a sprocket or gear 902 that can drive a belt through a continuous loop 904 to a lower sprocket or gear 906.

[0065] In various embodiments, any strut may include a non-linear shape. In various embodiments, to accommodate the non-linear shape, the belt may remain substantially straight, but the width of the belt storage cavity 131 (the space between the belt and the inner wall of the strut cavity) may vary. In various embodiments, the strut may include a pulley (e.g., a roller pulley) configured to create a curve for the belt 130 to follow. In various embodiments, a low friction pad may be positioned at any suitable location within the belt storage cavity 131. In various embodiments, any combination of the above three methods may work together to achieve a non-linear strut shape. In various embodiments, the leading edge of the strut may include a non-uniform profile (viewed from top to bottom).

[0066] The various components disclosed herein (e.g., struts, nose cones, fairings, skegs) can be formed from a variety of materials including metals (e.g., aluminum, steel, titanium, etc.), rigid polymers and plastics, wood, etc. In various embodiments, the various components can include composite materials (e.g., carbon fiber, fiberglass, etc.). In various embodiments, the various components can include rubber. In various embodiments, the various components can include thermoplastics. In various embodiments, the various components can include any suitable metal-based alloy. In various embodiments, the various components can include materials with high thermal conductivity and high corrosion resistance. In various embodiments, the various components can include one or more coatings (anodization, powder coat, chemical vapor deposition, paint, etc.). In various embodiments, the various components can be formed from two or more materials (i.e., the nose cone can be primarily aluminum with a rubber-based tip).

[0067] 10A-10B illustrate computational fluid dynamics visualizations of the disclosed dual strut (top) and a conventional single strut (bottom). In various embodiments, this half-body analysis was used to understand preliminary fluid dynamic effects and implications of a dual strut compared to a single strut. The plots in FIG. 10A-10B show laminar flow as evidenced by the uniform shading of the majority of the fluid flow values ​​(the darker portions of the plot in FIG. 10B are above the water line).

[0068] FIG. 11 illustrates a graphical representation of the initial computational fluid dynamic drag results of the disclosed dual strut (left) (approximately 37,500 Newtons at 150 iterations) compared to a conventional single strut (right) (approximately 45,500 Newtons at 150 iterations). This simulation demonstrates the fluid dynamic advantages of the dual strut compared to the single strut.

[0069] Feedback control of variable path cooling water flow The present disclosure also provides an efficient thermal management system for propulsion systems that generate waste heat as a by-product. An intelligent variable flow path cooling loop includes at least a reservoir, a pump, a drive module, a pass-through valve, and a radiator through which the working fluid is pumped. An internal cooling pipeline connects each component through a combination of serial and parallel flow paths. In various embodiments, an active feedback loop uses data from various inputs and sensors to access the relative cooling requirements of different components and directs the flow accordingly. In various embodiments, thermocouples are embedded in the system to measure the temperature of the fluid and surrounding areas. In various embodiments, thermometers are utilized to measure said temperatures. In various embodiments, the sensors are externally accessible for maintenance. In various embodiments, the sensors are embedded in the manufacturing of the pipeline. A single input / output valve or manifold is used in conjunction with a flow meter to connect the pipeline into multiple loops that can be automatically adjusted. Each loop can be selectively opened to various degrees according to the requirements of the components and the operating conditions of each component in the loop. This system is energy efficient and heat dissipating. In various embodiments, the loop is placed in close proximity to a heat generating system, such as a motor or leading edge of a moving vehicle, such as a boat hull or lower unit torpedo.

[0070] In various embodiments, the working fluid is a water-glycol mixture to reduce the risk of cooling water freezing and add control over fluid flow through sensitive components. In various embodiments, the working fluid is water (e.g., deionized water). In various embodiments, the working fluid is an organic compound (e.g., ethylene glycol, diethylene glycol, propylene glycol, polyalkylene glycol, mineral oil, silicone oil, ethanol, methanol, fuel, etc.). In various embodiments, the working fluid is a refrigerant (e.g., ammonia, R-12, R-22, R-134A, R-744, R-717, HCFC, HCS, R-407C, R-404A, R-410A, R-448A, R-449A, etc.). In various embodiments, the fluid is actively cooled by one or more refrigeration systems in addition to or in place of the systems described herein. For example, according to various embodiments, the fluid may release heat as it passes through a heat sink as described herein, or may be actively cooled using a condenser or other known refrigeration techniques in conjunction with a refrigerant such as R-134A.

[0071] A system that controls the relative flow to different waste heat generating components can dissipate heat more efficiently and minimize additional power requirements to run the pump. The present disclosure uses an array of temperature, pressure and flow sensors to assess cooling requirements and direct the relative flow of working fluid as needed. Additionally, based on user input data such as throttle percentage, the system can preemptively direct flow to specific components to slow temperature gains. For example, if a specific motor or motors are throttling up, the system can direct additional working fluid (e.g., increasing the working fluid volumetric flow rate) to the specific motor(s). In various embodiments, the system can turn on one or more proximate loops to assist in cooling the throttled-up component(s). For example, there can be three loops surrounding the throttled-up motor or located within the motor or housing. The system can have a single loop that detects a low initial temperature and has no working fluid or actively cools the motor. The temperature may rise as the motor operates, and utilizing a temperature sensor, among other sensors such as a pitot tube (located on the hull or motor housing) or a flow meter, the system may then command the second loop to flow working fluid to the motor. In the same example, if the motor temperature continues to rise or exceeds a temperature threshold, the system may turn on a third loop to send working fluid towards the motor and back in an attempt to cool it. In another example, the system may not only actively command multiple loops, but may also command an active coolant system to cool the fluid at a higher rate or reduce the operating temperature to cool the motor (or other relatively hot components). In various embodiments, and continuing with the previous example, the system may command all three loops to flow working fluid in proximity to a hot motor.If the temperature continues to rise or a failure is experienced, the system can then actively cool the working fluid to a sub-normal operating temperature, thereby increasing the capacity to absorb thermal energy from the motor with temperature fluctuations as well as a larger capacity increase. Total system flow can also be reduced as heat dissipation requirements are reduced to minimize power consumption from the pump.

[0072] FIG. 12 depicts a schematic of a single pump, multi-flow cooling channel for cooling a marine propulsion system. In various embodiments, there may be multiple pumps and any other components as described herein. For example, there may be a primary and secondary reservoir, or a multi-reservoir system, based on the cooling time from the working fluid. The reservoir 461 stores the working fluid (e.g., water) that is used as a heat sink for the power electronics. Connected in series directly to the reservoir is a pump 462. The pump provides a positive pressure gradient through the system, circulating the cooling water. The pump includes one or more integral flow meters connected to a central cooling control unit 4613. Connected to the output of the pump via tubing is a temperature sensor 463. The temperature sensor measures the steady state temperature of the cooling water before it reaches any heat generating components. After passing the temperature sensor, the flow path is split from a single flow to a multi-flow output. In some embodiments, this may use a single variable valve with one input and multiple outputs. In various embodiments, this may be accomplished using multiple valves connected to one or more manifolds of non-limiting inputs and outputs. Each of these valves in this example may be an adjustable valve. In various embodiments, a subset of the valves are adjustable valves (i.e., open or close a selectable distance, percentage, amount, or similar measurement). In various embodiments, all of the valves are adjustable valves. In some embodiments, a flow splitter is used with an adjustable valve 464 connected to each output of the splitter. The valves 464 have an integrated flow sensor to calculate mass flow rate through a dedicated flow path. In various embodiments, the flow meter may additionally or alternatively capacitively measure flow rate and / or temperature of the fluid embedded in a single sensor or suite of sensors. Each path has one or more designated components that are cooled. In this embodiment, the motor 465 is connected in parallel with the inverter 4611 and the charger 4612.The motor 465 has an integral thermocouple 466 that outputs to a central cooling control unit 4613 either remotely or via a wired connection (e.g., the thermocouple 466 can be mounted to the motor housing or located on the stator / rotor of the motor). The output from the integral thermocouple 466 is used to calculate the relative flow requirements along the paths. If the temperature exceeds a predetermined limit, the valve 464 is opened further to increase the flow rate. Connected to the output of the thermocouple 467 is a splitter 468 to combine each of the flow paths. For the inverter 4611 and charger 4612, there is a duplicate array of thermocouples and valves to measure the temperature and flow of each cooling water flow path. The splitter 468 has a single output direction with multiple inputs to combine the flows together. Connected to the single output of the splitter is an additional thermocouple 469 that is also connected to the central cooling control unit 4613. The total thermal energy added to the flow can be calculated by measuring the change in temperature between the thermocouple 463 and the thermocouple 469. The total heat energy added to the flow paths gives a value for the losses and overall thermal efficiency through the system. All flow then passes through a heat sink device 4610. The heat sink radiates the excess heat energy to the surrounding body of water to bring the circulated fluid back to a steady state temperature. Again, a connection via hoses or tubes allows the fluid to be returned to a reservoir and recirculated around the system.

[0073] FIG. 13 is a schematic diagram of one embodiment of a cooling loop system operating to cool a high temperature charger in charging mode. When charging mode is enabled, a central cooling control unit 4649 closes each flow path except through the charger. A reservoir 4641 holding a predetermined amount of working fluid (e.g., water) acting as a heat sink is connected in series first to a pump 4642 and then to a thermocouple 4643. When in charging mode, only a valve 4644 is open, allowing the cooling water to flow. The charger 4645 has an integral thermocouple and outputs the rate of charging. After passing through the charger, the cooling water passes through an additional thermocouple 4646 connected to the central cooling control unit 4649. The total waste heat generated by the charger is calculated to determine the thermal efficiency. The temperature of the charger is mapped over time to find the steady state temperature. If the temperature of the charger continues to rise above a predetermined limit, the system increases the power to the pump to increase the flow rate and therefore the heat dissipation. As the charger temperature continues to increase, the rate of charging will decrease until it reaches a steady state temperature below the charger's limit. Before returning to the reservoir 4641, the cooling water passes through a heat sink 4647 to dissipate the heat being added to the flow by the charger. Finally, in this embodiment, an additional thermocouple 4648 is added to calculate the total thermal energy dissipated by the heat sink.

[0074] FIG. 14 is a schematic diagram of a cooling loop system that operates to cool the high temperature motor and inverter, bypassing the charger. A volume of working fluid (e.g., cooling water) is held in a reservoir 4611. Connected to the output of the reservoir is a pump 4612 and a thermocouple 4613, which provide a pressure gradient through the system and calculate the total heat energy. Valves 4614 and 4610 are individually controlled based on the relative temperatures of the heat generating components in their respective loops. In a given operating scenario, if both the motor 4614 and the inverter 4619 are within a safe operating temperature range, the power to the pump 4612 can be reduced to improve overall system efficiency. If either the motor 4615 or the inverter 4619 require additional heat dissipation, a larger percentage of the flow can be directed as needed by adjusting the valves 4614 and 4610. This allows the pump 4612 to reduce its power requirements as the system more effectively directs flow to where it is needed. The flow from each heat generating component is returned together before passing through an additional thermocouple 4616, which measures the total heat input to the flow. Before returning to the reservoir 4611, the flow passes through a heat sink 4617, which dissipates the added thermal energy into the surrounding body of water.

[0075] Integrated motor-gearbox with reduced gear ratio This disclosure details how to constrain the planet carrier of a planetary gearbox set to achieve a 2:1 gear reduction ratio using a standard gear set with a 3:1 reduction. The reduced gear reduction ratio can be achieved by using a new design to constrain either the sun gear or the planet carrier. In various embodiments, the gear set is fully contained and sealed in oil to ensure sufficient cooling and lubrication. In various embodiments, the housing is designed so that there is no additional diameter added to the motor gearbox drive train. If a single stage is used, ratios from 3:1 to 10:1 can be made. Additional stages can be added to increase the ratio.

[0076] FIG. 15 shows a cross-sectional view of the planetary gear set 56100. The outer ring gear 56101 typically has a circular pattern of through holes used to constrain the ring. The teeth of the ring gear 56101 mesh with each of the planet gears 56102. The planet gears 56102 are equally spaced from each other and may be equiangularly arranged around the planet carrier 56105. The planet gears 56102 also mesh with a central sun gear 56104. The ratio of the number of teeth between the sun gear 56104, the planet gears 56102, and the ring gear 56101 determines the output ratio of the gearbox. In various embodiments, a set screw secures the outer diameter of the planet carrier 56105 to an output spline configured to couple to another component (e.g., an output shaft) thereby transmitting rotational motion from the input shaft to the output spline.

[0077] FIG. 16 shows a side profile half cutaway view of the motor along with the gear reduction assembly. The motor shaft 561 is fixed with a bearing 562 at the rear of the motor 56200 and a second bearing 563 at the front of the motor. Two or more bolts 564 attach the spacer 5612 to the motor body via mounting holes 569. In various embodiments, the spacer is configured to hold the planet carrier fixed at connection points 5613. The shaft 561 from the motor passes through the center of the bearing carrier and meshes with the sun gear 56104 and is axially constrained using a snap ring 56104. The gear set is flipped 180 degrees so that the sun gear 56104 is on the output side rather than the input side of the planetary gear set 56100. The motor spacer 5612 has a bearing 565 pressed on the outside diameter to increase the stiffness of the rotating body. The bearing 565 is held in a pocket bore on the input side of the gear set housing 567. Both the input and output halves of the gearset housing 567 have locating dowels 568 to maintain precision between each body. In various embodiments, the output portion of the gearset housing 567 has an additional bearing 5610 to ensure radial alignment with the central rotational axis. In various embodiments, the planetary gearset 56100 is contained in a closed volume within the gearset housing 567. In various embodiments, the planetary gearset 56100 is oil bathed for lubrication and cooling. At least one input seal 566 and at least one output seal 5611 are added around the shaft on the input and output sides to limit any oil loss along the shaft 561.

[0078] FIG. 17 shows an isolated, exploded cross-sectional view of the planetary gear set 56100 and the spacer 5612 used to restrain the planetary carrier 56105. A circular pattern of countersinks 569 is used to align and secure to the input motor. The gear set 56100 has two internal splines, one in the central sun gear 56104 and the second that mates with the spacer 5612. The spacer 5612 has a corresponding male spline 5615 to mate with the planet carrier 56105. There is an additional set screw 56106 to fix the outer diameter of the planet carrier splines. In this configuration, the outer ring 56101 can rotate freely with the sun gear 56104 driven by the motor.

[0079] FIG. 18 shows a cross-sectional view with the input motor and motor spacer removed for clarity. The motor shaft 561 is splined 566 to mate with the input sun gear 56104. The shaft passes through larger female splines on the planet carrier 56105. The outer housing is free to rotate and sits radially on the shaft with bearings 565 and 5610. The inner diameter of bearing 565 is mounted directly on the motor shaft 561. The input bearing 565 sits radially on the motor spacer to ensure consistent alignment.

[0080] 19 shows a simplified labelled schematic of a planetary gear set. The motor (input) shaft 561 is connected to a central sun gear. Each of the planets is connected to an output shaft 5614 by a planet carrier 562.

[0081] FIG 20A illustrates a motor 56200 having a shaft 561 with a spacer 5612 coupled to the exterior of the motor 56200. FIG 20B illustrates a planetary gear set 56100, a spacer 5612, and a motor 56200.

[0082] Figure 21A illustrates a cross-sectional view of a planetary gear set, a spacer, and a motor, and Figure 21B illustrates a cross-sectional view of a gear set housing coupled to a carrier and a motor.

[0083] FIG. 22A illustrates a cross-sectional view of the planetary gear set 56100. FIG. 22B illustrates a cross-sectional view of the planetary gear set and the gear set spacer 56812. As shown in FIGS. 22A and 22B, the planetary gear set 56100 includes a proximal portion 56807a and a distal portion 56807b (collectively, 56807) of a gear set housing. In various embodiments, the gear set housing 56807 substantially encloses the planetary gear set 56100. In various embodiments, the gear set housing 56807 includes a fluid configured to cool and / or lubricate the planetary gear set 56100.

[0084] FIG. 23 illustrates the gearset housing 56907 with the output splines 56920 highlighted. In various embodiments, the gearset housing 56907 is coupled to a carrier of a planetary gearset (not shown) and configured to rotate at a different (e.g., lower) RPM than the input shaft from the motor. As shown in FIG. 23, the housing is generally cylindrical and includes splines 56920 on a distal (away from the motor) side. In various embodiments, the splines 56920 are configured to rotatably couple the gearset housing 56907 to another rotating component of the system (e.g., a shaft). In various embodiments, the splines 56920 include male splines that protrude (e.g., extruded) outwardly from a surface of the gearset housing 56907. In various embodiments, the splines 56920 include female splines formed (e.g., extrusion cut) into a surface of the gearset housing 56907. In various embodiments, the splines 56920 are formed to have a central bore aligned with the input shaft of the motor. In various embodiments, the input shaft of the motor extends through the spline 56920. In various embodiments, the spline 56920 can include any suitable shape configured to transmit rotational motion from the gear set housing 56907 to another rotating component. For example, as shown in FIG. 23, the spline 56920 includes a plus shape.

[0085] Actively cooled epicyclic gearing This disclosure details a system and method for more effectively dissipating heat from a planetary gearbox using a new design for the shape of the heat sink. The improved dissipation allows the gearbox to operate in a continuous state at higher revolutions per minute (RPM), thereby transmitting more power over time. Within the gear set of a planetary gearbox, the bearings of each planet gear are a localized point of heat concentration. By using a heat sink spatially closer to the bearings and running cooling water on the surface of the gears rather than just the outer diameter, more heat can be drawn away from the gears. Further advantages include a more compact design and lower weight, increasing the power to weight ratio. The system can be seamlessly integrated into existing cooling water loops to reduce complexity. In various embodiments, the system can be implemented within a boat motor. In various embodiments, the system can be located in a boat transmission. In various embodiments, the system can be implemented in one or more locations on the vessel, such as multiple instances of the transmission, a larger gearbox, or a drive train. In various embodiments, the planetary gearboxes may be positioned in multiple orientations in space, such as horizontally, vertically, or at an angle to the overall gearbox.

[0086] FIG. 24 shows a simplified labeled schematic diagram of a planetary gear set. An input shaft 661 is connected to a central sun gear. Each of the planets is connected to an output shaft 662 by a planet carrier. In various embodiments, the central sun gear is fixed and one or more other components are configured to rotate and / or orbit relative to said fixed point. In various embodiments, the ring gear may be fixed and other components may be configured to rotate and / or orbit relative to said ring gear. In various embodiments, another component to which the system is attached may be fixed in space and the planetary gearbox may be configured to orbit and rotate relative to said outer point.

[0087] FIG. 25 shows a cross-sectional view down the middle of the motor and gearbox drive train. In various embodiments, the motor is an electric motor. A shaft 661 extends from the motor and engages the central sun gear of the gearbox. In various embodiments, the sun gear is directly coupled to the shaft via splines, as shown in FIG. 25. In various embodiments, the sun gear is coupled using a shaft adapter 661b. An annular shaped cooling water reservoir 664 is mounted to the motor 662 and surrounds the input shaft of the gearbox 661b. The reservoir has cooling water ports 663 for circulating fresh cooling water across the diameter of the gearset 666. A mounting plate 665 is used to locate the gearset on the input shaft 661b and separate the oil and cooling water volumes. A radial shaft seal 667 (e.g., an O-ring) keeps the oil local to the gearset 666 and prevents mixing of the cooling water and lubricating oil. A second radial shaft seal 668 is used to contain oil from leaking around the gearbox output shaft 6610. An output bearing 669 is used to position the output shaft in series with the input shaft to minimize additional wear on the gears. This design allows the cooling water in volume 664 to be much closer to the gear set and to dissipate heat more effectively.

[0088] FIG. 26 shows an isometric view of the gearbox with integrated coolant housing. The input motor, input shaft, and output shaft have been removed for clarity. A circular pattern of bolts with sealing heads 661 are used to secure the input side of the gearbox to the motor. The coolant volume is toroidal in shape with a central aperture 662 through which the input shaft extends. The advantage of the toroidal reservoir 664 being adjacent to, but fluidly separated from, the planetary gearset is that it keeps the coolant close to the input shaft to draw heat from the output shaft of the motor that drives the central sun gear 669 and the input shaft of the gearbox. The toroidal reservoir 664 has a separator plate 665 with seals 667 to confine the coolant except for the input and output ports 6611. The separator plate 665 is used as a thin boundary 6612 between the oil and coolant fluid volumes. The gearset is held to the separator plate 665 using a circular pattern of bolts 6613. The volume around the gear set is sealed with a cover 6612 and a radial seal around the output shaft 668. The output shaft sits in the centre of the gear set with bearings 6610.

[0089] Automatic power transmission belt tensioning system for marine propulsion systems To enable the use of the belt for power transmission between the prime mover and the propeller shaft, the structure holding the prime mover is affixed to the center and pulled up or adjusted by a set of pulling screws. Equal adjustment of the pulling screws allows tensioning of the belt by moving the power heads uniformly to the center, while unequal adjustment tilts the power heads including the shafting so that the power heads can be aligned with the propeller shaft. Connecting a motor to each set of pulling screws allows them to be controlled electronically. Force sensors on each of the pulling screws can be used to determine the tension of the belt, as well as the belt alignment. The sum of the measured forces minus the weight of the power heads gives a total belt pulling force equal to twice the tension, and the distribution of forces between the sensors can be used to calculate the position of the belt relative to the pulling screws. The sensor information can then be used to control the pulling screws to ensure proper belt tension and alignment.

[0090] FIG. 27 shows a side view of an outboard motor drive train. In various embodiments, the engine can be an electric boat motor. A main lifting plate 761 is supported from a center upper collar 762. The main lifting plate 761 supports a power head 763, which includes a drive shaft with a drive sprocket 764. The drive sprocket 764 transmits power to a propeller shaft sprocket 765A via a synchronous belt 766. In various embodiments, the propeller shaft sprocket 765A rides on a propeller shaft 765. The position of the propeller shaft 765 is fixed relative to the center upper collar 762. The main lifting plate 761 is supported via two or more lifting screws 767. For example, the lifting plate 761 can be coupled to the upper collar 762 using four lifting screws (two on each side). Additionally, the further the main lifting plate 761 and associated drive sprocket 764 are pulled away from the center collar 762, the greater the tension in the synchronous belt 766. Uneven adjustment of the pull screw 767 can change the alignment between the drive sprocket 764 and the propeller shaft sprocket 765A. When the drive sprocket 764 and the propeller shaft sprocket 765A are aligned, the belt 766 can be made to run centered on the drive sprocket 764 without drifting to either side.

[0091] By intelligently controlling the height of the drive sprocket 764 via tension screw 767, the tension in the belt 766 can be controlled and set to only what is necessary for a given power transmission requirement, thus reducing friction losses.

[0092] FIG. 28A shows a top view of the power head 763 and the center upper collar 762 with some power head components hidden to provide a clear view of the lift screws 767. In various embodiments, the lift screws 767 can be divided into two or more groups. For example, the lift screws can be divided into front lift screws 767A and rear lift screws 767B. Within each group of lift screws 767A and 767B, the movement of the screws is synchronized to maintain the left and right level of the main lift plate 761. By measuring the load placed on each set of lift screws 767A and 767B compared to the total load on all lift screws 767, the position of the belt 766 on the drive sprocket 764 can be determined. Uneven adjustment of the front lift screws 767A and rear lift screws 767B can allow the drive sprocket 764 to tilt without changing its vertical position. When one end is up, the belt is off. This method can be used to center the belt on the drive sprocket 764 to ensure alignment with the propeller shaft sprocket (not shown).

[0093] FIG. 28B illustrates a cross-sectional view of the belt 766 and the motor shaft 7610. In various embodiments, as the motor shaft 7610 rotates in one direction (e.g., clockwise), one side 766a of the belt 766 is in tension (the tight side) and the other side 766b of the belt 766 is not in tension (the slack side). In various embodiments, the load cells positioned under the lifting plates do not experience substantially the same forces (and therefore do not exhibit substantially the same loads) during operation of the motor. In various embodiments, the load cells on one portion (e.g., half) of the lifting plate 761 corresponding to the tight side 766a of the belt 766 experience a higher force (compression) compared to the load cells on another portion (e.g., half) of the lifting plate 761 corresponding to the slack side of the belt 766. This is due to a reaction force between the lifting screw on the tight side of the belt and the lifting plate, which balances the moment created by the tension in the belt 766 (as torque is applied to the belt 766).

[0094] FIG. 29 shows a close-up of the lift screw with actuator and sensor installed. The rotary actuator 767C is configured to rotate the threaded rod 767D when actuated. In various embodiments, the actuator 767C can be bidirectional (i.e., can rotate clockwise and counterclockwise). Rotation of the threaded rod 767D screws the rod into or out of the central upper collar 762, adjusting the height of the lifting platform 767E on which the primary lifting plate 761 rests. Between the lifting platform 767E and the primary lifting plate 761 is a load cell 767F configured to measure how much force is exerted downward on the lifting platform 767E by the primary lifting plate 761.

[0095] Onboard high voltage battery charging system for outboard propulsion system An onboard battery charger (OBC) can be included in all forms of electric vehicles incorporating the present invention. The OBC accepts alternating current and provides direct current to the electric boat for charging, and typically uses an inverter to convert AC to DC (e.g., converts sinusoidal AC to approximate constant DC). In various embodiments, such as on a boat, the OBC is typically a separate component that is integrated into the dock slip (i.e., not connected to the boat). Additionally, the OBC is typically fan-cooled and consumes significant energy to maintain an operating temperature (e.g., cooling) while charging.

[0096] Various embodiments described by the present disclosure provide an OBC integrated into an outboard motor of an electric boat. In various embodiments, the OBC is located within the housing of the outboard motor. In various embodiments, the OBC is integrated into the same thermal management system (e.g., closed heat transfer circuit) as other heat-generating components of the marine propulsion system (e.g., electric motor, inverter, etc.). The integration of the OBC into the outboard motor allows AC power to be plugged directly into the outboard motor, without generating additional waste heat near potentially damaged components such as the battery. In various embodiments, the battery is housed within the hull of the boat.

[0097] In this system, a pump is used to provide cooling water to the inverter, motor, and OBC. In various embodiments, the OBC does not require cooling at the same time as the inverter and motor because charging from AC power only occurs when the vehicle is stationary and plugged into AC power. In various embodiments, the heat transfer circuit includes a valve configured to allow flow to or restrict the flow of cooling water from the OBC.

[0098] When cooling water is needed to cool the OBC (e.g., during recharging), the pump is powered and a valve allows cooling water to flow through the OBC. When cooling water is not needed by the OBC (e.g., during motor operation), the valve is closed, thereby restricting the flow of cooling water to the OBC. In various embodiments, while charging the vehicle, the cooling water bypasses the inverter and motor. In various embodiments, the cooling water flows through a heat exchanger and rejects heat to the surrounding water (e.g., the ocean). Only a portion of the cooling water passes through the OBC, which can reduce potential cooling capacity due to lack of flow over the heat exchanger resulting from the movement of the vehicle through the water. In various embodiments, the OBC generates less waste heat than the motor and inverter.

[0099] FIG. 30 shows an isometric view of the cooling loop of an outboard motor. A pump 861 moves coolant throughout the components of the outboard motor. Coolant flows from a coolant reservoir 862 through a reservoir-pump-tube 863A. From here, the coolant flows through the power electronics, including inverter 864, motor 865, and OBC 866, before flowing through a powerhead-lowerunit-tube 863B to an anti-ventilation plate (AVP) 867 and a lower unit (LU) 868 where heat exchange with the surrounding water takes place. Here, cooled, the coolant flows back into the coolant reservoir through a coolant return cube 863C.

[0100] FIG. 31 shows an isometric view of the cooling loop of an outboard powerhead. From the pump 861, the coolant flows through the pump-inverter tube 863D to the inverter 864. After passing through the inverter 864, the coolant flows through the inverter-motor tube 863E to the motor 865. The motor coolant output is connected to the powerhead-LU tube 863B. When in charging mode, the solenoid valve 869 opens, allowing the coolant to flow from the pump-inverter tube 863D through the OBC 866 to the OBC-cold side tube 863F and into the OBC-hot side tube 863G which enters the powerhead-LU tube 863B. When not in charging mode, the alternative coolant path through the OBC 866 is closed, leaving the coolant flow intact. When the solenoid valve 869 is open, the coolant has the option of flowing either through the OBC 866 or through both the inverter 864 and the motor 865. The lower pressure drop in the coolant path through the OBC 866 will cause a larger portion of the coolant flow to flow through the OBC 866 before returning to the reservoir 862 through the heat exchanger.

[0101] FIG. 32 shows an isometric view of a boat 8610 with an outboard motor 8611. The OBC 866 and high voltage battery 8612 are highlighted. The boat 8610 is docked next to an AC power source 8613. An AC power cable 8614 runs from the AC power source 8613 to the outboard motor 8611. The AC power is routed to the OBC 866 where it is converted to an appropriate DC voltage and transmitted to the high voltage battery 8612 via a DC power cable 8615. The power stored in the high voltage battery 8612 can then be used to operate the outboard motor 8611.

[0102] The description of various embodiments of the present disclosure has been presented for the purpose of illustration, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used in this specification have been selected to best express the principles of the embodiments, practical applications or technical improvements to the technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. 1. A heat transfer device comprising: a reservoir configured to contain a working fluid; a pump fluidly coupled to the reservoir; a splitter fluidly coupled to the pump and coupled to a plurality of fluid flows; a first temperature sensor disposed between the pump and the splitter, the first temperature sensor configured to measure a first temperature of the working fluid; At least one of the plurality of fluid flows is An adjustable valve; a motor fluidly coupled to the adjustable valve; a second temperature sensor integrated into the motor, the second temperature sensor configured to measure a second temperature of the motor; a third temperature sensor disposed downstream of the motor and configured to measure a third temperature of the working fluid; and a combiner fluidly coupled to each of the plurality of fluid flows and configured to combine each of the plurality of fluid flows; a fourth temperature sensor disposed after the combiner and configured to measure a fourth temperature of the working fluid; and a heat sink fluidly coupled to the combiner and the reservoir; The heat transfer device, wherein the second temperature sensor is configured to provide a control signal to a control unit to thereby control fluid flow through at least one of the adjustable valves.

2. The apparatus of claim 1 , wherein the heat transfer device is integrated into a marine propulsion system.

3. 3. The apparatus of claim 1 or 2, wherein at least one motor is coupled to an inverter.

4. The device according to any one of claims 1 to 3, wherein at least one motor is coupled to a charger.

5. 5. The apparatus of claim 1, further comprising a fifth temperature sensor disposed downstream of the heat sink, the fifth temperature sensor configured to measure a fifth temperature of the working fluid.

6. An apparatus according to any one of claims 1 to 5, wherein the adjustable valve is a continuously adjustable valve.

7. An apparatus according to any one of claims 1 to 6, wherein the working fluid is a refrigerant.

8. An apparatus according to any one of claims 1 to 7, wherein the working fluid is a water-glycol mixture.

9. The apparatus of any one of claims 1 to 8, wherein the splitter is a manifold.

10. 10. The apparatus of claim 1, wherein the splitter's multiple outputs are each coupled to an adjustable valve, each of the adjustable valves further comprising a flow sensor.

11. An apparatus according to any preceding claim, wherein each of the adjustable valves is individually controlled.

12. 1. A gearing system comprising: a motor having a shaft, the shaft extending from the motor to a terminal end external to the motor; a planetary gear set including a sun gear, two or more planetary gears coupled to a carrier, and a ring gear, the planetary gear set having a proximal side facing toward the motor and a distal side facing away from the motor, the sun gear being disposed on the distal side; a housing surrounding the planetary gear set, the housing being coupled to the ring gear; an axle extending at least partially through the housing and the planetary gear set, the shaft coupled to the sun gear; A gearing system wherein when the shaft rotates at a first revolutions per minute (RPM), the housing rotates at a second RPM that is less than the first RPM.

13. The gearing system of claim 12 further comprising a spacer disposed on said shaft and between said planetary gear set and said motor.

14. A gearing system according to claim 12 or 13, wherein the carrier is coupled to the spacer.

15. A gearing system according to any one of claims 12 to 14, wherein the ratio between the first RPM and the second RPM is 2.

16. 1. A system comprising: A motor; an input shaft extending from the motor to a terminal end; a planetary gear set adjacent to and in contact with the reservoir, the planetary gear set including a sun gear, two or more planetary gears coupled to a carrier, a ring gear, and an output shaft, the input shaft being coupled to the sun gear and the output shaft being coupled to the carrier; a reservoir disposed between the motor and the planetary gear set, the reservoir having a toroidal shape about the input shaft, the reservoir being fluidly isolated from the shaft and the planetary gear set.

17. 1. A marine vessel propulsion device, comprising: A first drive shaft; a lift plate fixed relative to the first drive shaft; The upper central color and a first strut extending from a proximal end to a distal end and a second strut extending from a proximal end to a distal end, each of the first strut and the second strut having an internal belt gap, the first strut aligned with the second strut and the first strut spaced apart from the second strut, and the proximal ends of the first strut and the second strut coupled to the central upper collar; a lower unit coupled to the distal ends of the first strut and the second strut, the lower unit having a second drive shaft, the central upper collar being fixed relative to the second drive shaft; a belt rotatably coupling the first drive shaft to the second drive shaft, a first portion of the belt being disposed within the internal belt gap of the first strut and a second portion of the belt being disposed within the internal belt gap of the second strut; and one or more pull screws connecting the lift plate to the central upper collar, where adjusting the one or more pull screws varies the distance between the lift plate and the central upper collar, thereby adjusting tension in the belt; and an actuator disposed on each of the one or more lift screws.

18. a lifting platform disposed between the lifting plate and the central upper collar; a load cell in contact with the lift plate and the lift platform; 20. The marine propulsion device of claim 17, further comprising:

19. 1. A system comprising: An electric boat motor; a lower unit coupled to the electric boat motor, the lower unit including a propeller; An inverter; an onboard battery charger coupled to the inverter and to one or more high voltage batteries; 1. A heat transfer circuit comprising: a reservoir having a working fluid; A pump, A valve, a first tube fluidly coupling the reservoir to the pump; a second tube fluidly coupling the pump to the valve; a third tube fluidly coupling the valve to the inverter; a fourth tube fluidly coupling the valve to the onboard battery charger; a fifth tube fluidly coupling the inverter to the motor; a sixth tube fluidly coupling a motor to the lower unit; a seventh tube fluidly coupling the onboard battery charger to the sixth tube; an eighth tube fluidly coupling the lower unit to the reservoir; a heat transfer circuit comprising: when in a charging configuration, the valve allows hydraulic fluid to flow through the fourth tube to the onboard battery charger; When in an operating configuration, the valve does not allow hydraulic fluid to flow through the fourth tube.

20. 1. A method for recharging an electric boat, comprising:

1. An electric boat having a hull, an outboard motor coupled to the hull, and one or more rechargeable batteries disposed within the hull, the outboard motor including an electric motor and an onboard battery charger; coupling the onboard battery charger to an alternating current source thereby charging the one or more rechargeable batteries.

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